Wikipedia:Reference desk archive/Science/April 2006

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April 1[edit]

is this supposed to be funny?[edit]

for some reason whenever I edit a question it duplicates the content at the bottom of the page instead of editing the origional? Are the developers having a bit of april fools fun with us?--205.188.116.74 00:14, 1 April 2006 (UTC)

  • What the hell, April 1st just jumped to the middle of the page? this isn't funny--205.188.116.74 00:15, 1 April 2006 (UTC)

Soda Vending Machines[edit]

On a hot summer's day, there's nothing better than an ice cold soda from a soda vending machine. These machines obviously act like refrigerators, lowering the temperature of the drink as cold as possible without freezing it.

But what happens when the vending machine is outdoors and the weather is below freezing? Is the vending machine essentially acting as a heater to bring the soda up above freezing temperature? How is this done? Odd when you think about it, buying a nice warm soda on a cold winter's day! Am I understanding things correctly here?Loomis51 00:26, 1 April 2006 (UTC)

  • not really, aren't they just simple refrigerators, with some sort of thermostat to tell them when to turn on and off? also, who leaves a vending machine outside in the winter?--205.188.116.74 00:40, 1 April 2006 (UTC)
  • also you're talking about water with great amounts of sugar dissolved in it and compressed to 2 atm preasure, so it isn't exactly going to freeze at 0oC--205.188.116.74 00:41, 1 April 2006 (UTC)
  • K, maybe I should point out, I'm from Canada, where the temperature drops FAR below freezing. I should also point out that it's not unusual at all here to see a soda machine outside, at say, a gas station or whatever. I undertsand that the sugar content or increased pressure may affect the freezing point, but when its -25C I don't think those factors are relevant. My best guess is that the freon (or whatever other gas) used in refrigeration is kept at a constant temperature, slightly above freezing, and air is blown over it having the effect of keeping the entire "machine" slightly above freezing. So, it a weird sense, the vending machine is actually acting as a heater. I'm just wondering if anyone has a better explanation.Loomis51 01:14, 1 April 2006 (UTC)
  • I would think 2 atms worth of compressed CO2 would be more than enough to keep it from freezing regardless of temperature, I'm still not quite sure what the point of an outdoor vending machine would be, and why it would be preferable over the indoor variety, especially in a region that gets, as you said, below 248.15 kelvin outdoors--205.188.116.74 01:26, 1 April 2006 (UTC)
  • You can freeze soda in an ordinary freezer, much less a Canadian winter. Usually outdoor vending machines are emptied in winter - I can't recall seeing a full one in mid-winter. Rmhermen 03:18, 1 April 2006 (UTC)
  • More importantly: can a coffee machine keep coffee at the right temperature in a blast furnace? -Obli (Talk)? 00:43, 1 April 2006 (UTC)
      • I've seen many vending machines outside. Often in smaller towns, usually in front of Mom & Pop sorts of gas stations, where there is a low possibility of some local hoodlum damaging the machine. Dismas|(talk) 01:01, 1 April 2006 (UTC)
  • I've accidentally left a can of 7-Up in my parents' car once in sub-zero weather. The can froze and "exploded". - Cybergoth 04:12, 2 April 2006 (UTC)

Why are so many responses questioning the existence of outdoor vending machines? Where have you been living, under a rock? Trust me, they exist, and yes, even in sub-zero climates. As for the sugar explanation, haven't you ever heard of a popsicle? They freeze just fine in only slightly below freezing environments, and they're pretty much all sugar. Finally, as for the CO2/2atms argument, fine, I'll rephrase the question slightly: instead of a soda machine, make it a Snapple machine. No increased pressure, no carbonation. Loomis51 14:36, 2 April 2006 (UTC)

Good question. My guess is that as soon as the temperature of the soda is 32 F or 0 C or otherwise equal to or below whatever it's supposed to be, the refrigerator shuts off. I doubt there's a PLC in there that will begin to heat up the soda at some minimum temperature. But, I would think it possible to turn a refrigerator into a heater. As I recall a refrigerator is a kind of heater in "reverse". I believe a refrigerator expels air that is hotter than the ambient temperature (look at the coils on the back of your unit) and also colder than the unit's temp (i.e. inside the actual unit). So if you reversed that...well you'd have a kind of heater. In your example the unit would be pumping out air onto the street that is colder your Canadian winter air mass and then pumping in air warmer than the inside of the unit. Check out Refrigeration cycle and Carnot heat engine and if you're still in doubt studying this should give you a definitive answer:

http://www.amazon.com/gp/product/0072402962/002-8259327-5014420?v=glance&n=283155

-Snpoj 03:26, 3 April 2006 (UTC)

A refrigerator usually is insulated, so as to keep the outside heat outside. That has the added bonus of keeping inside heat in, so if the temperature outside plunges far below what the vending machine is at, it'll take quite a while for the (relative) heat inside to leak outside. So even if there's no reversal of the refrigeration process, the machine will act like a thermos. kmccoy (talk) 01:46, 8 April 2006 (UTC)

IUPAC name of PMMA[edit]

Is the IUPAC name of polymethyl methacrylate (plexiglas) "poly(methyl 2-methylpropenoate)" or "poly(methyl 2-methylpropanoate)" or "poly(methyl 2-methylpropionate)" ? The article was recently changed. Thanks, AxelBoldt 01:02, 1 April 2006 (UTC)

It's poly(methyl 2-methylpropenoate). The monomer, methyl 2-methylpropenoate, has a double bond, hence the -en-. —Keenan Pepper 15:22, 1 April 2006 (UTC)
Thanks! AxelBoldt 18:18, 1 April 2006 (UTC)

Why Did The Elephants Survive?[edit]

I can see how crocodiles and hippos survived the Cretaceous metorite impact that killed the other dinosaurs, but what about elephants? They couldn't all have been in the water at the time it happened. And they were too big to be underground with the small ratty mammals from whence we evolved. Why do we still see elephants today? --Fuhghettaboutit 01:15, 1 April 2006 (UTC)

Elephants didn't exist at the time of the dinosaurs. They're mammals, and the only mammals that possibly existed then were those "small ratty animals" that you mention that we evolved from. Just like us, believe it or not, elephants too evolved from those "small ratty mammals". Loomis51 01:24, 1 April 2006 (UTC)

Also, I think you need a little more research if you think it was a Cambrian explosion. The Cambrian Period ended hundreds of millions of years before the dinosaurs existed. You're thiking of the K-T Boundary at the end of the Cretaceous Period, probably caused by the impact of a meteor or asteroid near what is now Chicxulub in Mexico. Elephants - as Loomis points out (and hippos too for that matter) evolved far later than that impact. Grutness...wha? 01:34, 1 April 2006 (UTC)

The Cambrian explosion was not an explosion like a bomb; it was an explosion in the number and complexity of species. Maybe the original poster was having us on a bit? A couple of people fell for it pretty good :-). --Trovatore 01:47, 1 April 2006 (UTC)
Really sorry guys...I thought everyone would just chuckle (or not), but realize it was an april fools question--hard to imagine anyone packing that many misunderstandings (and I thought funny ones at that) into one question. The cambrian explosion...Boom!. --Fuhghettaboutit 01:57, 1 April 2006 (UTC)
Didn't think of that. It's still March 31 in Canada. --Trovatore 01:59, 1 April 2006 (UTC)
"crocodiles and hippos survived [the ... Explosion] that killed the other dinosaurs." fell into the category of, so ridiculous it just had to be serious (:205.188.116.74 02:02, 1 April 2006 (UTC)
Yeah, I thought as much, but the original question was no more crazy than a lot of the ones here, so I assumed stupidity good faith :) Grutness...wha? 02:01, 1 April 2006 (UTC)
Don't feel bad. It isn't one of those questions that begin with "Everyone knows..." as in "Everyone knows that Bush hates all non-white people, so why does he hang out with Condoleeza all the time?" or "Everyone knows that God hates gays, so why do we have to have a gay guy on every television show?" or "Everyone knows that playing the lottery is the best form of investment so why don't we have a lottery for the penguins so they can get rich and buy H3's to get back and forth between the water and their breeding grounds?" --Kainaw (talk) 02:40, 1 April 2006 (UTC)
Okay, this time I'm being serious. How does one go about punctuating an equilibrium and what are equilibriums made from that they're so hard to pierce? --Fuhghettaboutit 02:40, 1 April 2006 (UTC)
I prefer to punctuate equilibrium like this: "Equilibrium!!!!.....?" EWS23 | (Leave me a message!) 02:46, 1 April 2006 (UTC)

Once one accepts the dual nature of light as both a particle and a wave, then its clear that the inverse multiple ratio of the retrograde rotation of the planet Venus provides the best explanation for how one goes about punctuating an equilibrium. It's elementary. Loomis51 02:55, 1 April 2006 (UTC)

whoa! But you forgot to reverse the polarity of the neutron flow! Grutness...wha? 06:09, 1 April 2006 (UTC)
You dumbass, neutrons don't have polarity. You're talking about electrons. I'm still wondering if Loomis51's first response was serious or not. Dinosaurs did not exist at the time around the cambrian explosion.. -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 11:21, 1 April 2006 (UTC)
Not a Dr. Who fan, huh? ;) Grutness...wha? 12:15, 1 April 2006 (UTC)

My first response was actually serious. To be honest I didn't actually take into account the "Cambrian Explosion" part because, to be honest, I'm not all that familiar with Earth's ancient past. I just answered with what I do know, which is, that elephants did not exist at the time of the dinosaurs. However, having given the matter further thought, I think the truest answer to the question is that the elephants survived underwater by using their trunks as snorkels. Loomis51 14:06, 2 April 2006 (UTC)

Now let me do my elephant impression by turning my pants pockets inside out for ears and unzipping my pants. :-) StuRat 09:23, 4 April 2006 (UTC)

Vactrains[edit]

The above question about maglev trains got me reading the Vactrain article. In the article, it says that these trains could potentially move at 4000-5000 mph. My question is about how this would affect the people in the train. Wouldn't they be subjected to rather high g forces and wouldn't that limit the number of people that could ride the train? I would think it would be at the very least uncomfortable for the elderly and small children. Dismas|(talk) 01:19, 1 April 2006 (UTC)

1 G is a surprisingly fast, yet mild acceleration. It's comparable to a 0-60 time of 2.8 seconds, but anyone who's experienced fast acceleration in a sports car can tell you that when properly cradled by a seat it's not any sort of violent force on the body. Night Gyr 02:00, 1 April 2006 (UTC)
Remember that G forces and speed are only indirectly linked - the critical factor is acceleration, is how quickly do you reach your speed of 4000mph? And once you're at that speed, the passengers won't feel a thing, they can walk around as if the train was stationary (think about the last time you were on a normal train - unless you look out the window, there is no way for you to tell how fast you're going if the train's speed is constant). As for acceleration, a plane taking off subjects you to about two g's while accelerating down the runway, if you're sitting down, those kinds of forces hardly matter. It's highly unlikely a vactrain would accelerate at more than about the acceleration of a plane taking off at worst, so you would just need to be sitting down for the acceleration (which would probably last around three or four minutes), and then you can walk around as normal. Unless something went wrong, the train would have no reason to slow down during the journey, and once approaching the other end, the controller would light up the "fasten seatbelt" sign, you'd sit down for the deceleration, and that would be that. I don't really understand your comment about limited capacity - all you need is a seat with a seatbelt for every passenger, just like in an airplane - and, as you probably know all too well, you can cram a lot of people into a plane like that! :) — QuantumEleven | (talk) 09:44, 1 April 2006 (UTC)

However, slowing down at 1G (or even significant fractions thereof) would not be practical, as that would throw people out of their seats. My guess is that vactrains would a) accelerate at a lot less than 1G, and b) might use seats that swivel around mid-trip, so that the deceleration forces you back into your seat rather than out of it. But in any case, if you assume something quite mild like 0.3G, a train would take about 1040 miles to accelerate to 5000 mph. That sounds like a lot, but if you were travelling from New York to London the trip is about 3500 miles, so more than 1/3 of the trip would still be done at peak velocity. A trans-Pacific vactrain could potentially go even faster, or spend longer at vmax. --Robert Merkel

Strike Ridges?[edit]

Hi all - I'm in the process of trying to get an article up to FA standard, and therefore trying to get rid of redlinks, even if it means writing stubs on them myself :) It's a geography article (The Catlins), and one of the redlinks is in the geology section, which talks about strike ridges. I have no idea what a strike ridge is, and can't seem to find a definition of them anywhere. Anyone know anything about them? Grutness...wha? 02:06, 1 April 2006 (UTC)

"A strike ridge is a linear, asymmetric ridge formed by the differential erosion of inclined bedrock layers. One flank of the strike ridge is a steep slope cutting across several bedrock layers (antidip or scarp slope). In contrast, the other side of the ridge is a less steep slope conforming to the slope of the underlying bedrock layer (dip slope)." [1] --Fuhghettaboutit 03:21, 1 April 2006 (UTC)
Ex-the-LLENT! Many thanks! (Heh... I can use that for a stub article now!) Grutness...wha? 06:13, 1 April 2006 (UTC)
Welcome --Fuhghettaboutit 07:31, 1 April 2006 (UTC)

HIV[edit]

I work at a pharmacy and my boss told me today that some HIV drugs cause the virus count to be undetectable and someone getting an HIV test that has it and is on these drugs will show up negative in some cases. How is it possible to spread HIV if the viral count is undetectable and you show up negative on the test?

Caveat: I am not expert on this topic. But it seems to stand to reason that the tests used are sensitive to a threshold level of the antibodies (or whatever it is they test for). The fact that a person's body has, say, one part per million rather than 20 parts per million (and thus is at an undetectable infection level), doesn't imply that a third party can't be infected. A tiny amount of virus enters the body and multiplies. Remember, it only takes one pregnant roach to infest an entire apartment building. Awaiting expert confirmation or chastisement. --Fuhghettaboutit 07:43, 1 April 2006 (UTC)
Or, alternatively, you could read the AIDS and HIV test article. As far as testing goes, as well as testing for the presence of HIV, tests are usually conducted for the presence of AIDS antibodies, which the individual will have even if the virus has been reduced to undetectable levels. As far as transmission goes, while there does seem to be a connection between viral loads and infectivity, just because somebody has very low levels of virus in their blood doesn't necessarily mean that the levels are equally low in their semen or vaginal fluids. --Robert Merkel 14:15, 1 April 2006 (UTC)

One possibly more ominous reason is that the drugs may not treat HIV at all, but may only interfere with a particular testing method for HIV antibodies. Such a drug would be harmful, not helpful. Hopefully, clinical studies would show no reduction in mortality with such drugs and they would therefore not be approved for general use. StuRat 09:11, 4 April 2006 (UTC)

Eye Infections[edit]

I have been getting eye infections for the past year about every 3-5 weeks. I cant think of any reason why. I used to wear contacts, I stopped and I wear glasses now (because I thought it was because of the contacts), I dont touch my eyes, I threw away all my old eye drops, I wash my hands many times daily, and I have been to 9 different doctors and they act like its not a big deal. I told the last one, and he said "Well your eyes look perfectly healthy to me." That was a few days after I usd antibiotic eye drops. I got a convertable car about a year ago, I am not sure if its because I always drive with the top down and all the air that hits my eyes, but its driving me crazy. Any ideas or suggestions, or solutions would be appreciated.

Put the top up when you drive. I'm not kidding. I've had nothing but eye misery when driving around in an open convertible. Keep track of your symptoms in a notepad or something. Record what your symptoms are and when and where they began. If you treat the symptoms yourself, record that and the effectiveness of the treatment. You may want to have a friend take a picture of your eyes when the problem occurs so you can show the doctor. I had a year or more of bad experiences with eye problems as a kid and by the time I got to a doctor everything was always just fine. Till my mother took me to the emergency hospital during a really bad episode. I got the right diagnosis, proper care, medications and have been able to handle every similar problem since then with no trouble. Good luck. Ande B 07:13, 1 April 2006 (UTC)
The best solution: wear some big goggles! (Blowtorching goggles, for best effect) Tzarius 02:16, 2 April 2006 (UTC)

I got an eye infection from using moisturizing eye drops, I don't use them at all anymore. not sure if you are using them though. 24.193.235.188 07:41, 1 April 2006 (UTC)

Yes, eye drops, such as Visine, which claim they "get the red out", actually harm your eyes by blocking the supply of blood to the eyes (which is needed to prevent infections). StuRat 08:19, 4 April 2006 (UTC)

One thought, are you sure they aren't allergic reactions to pollen, etc. ?

Note that while a few cars are designed as convertibles, and have very little air flow into the passenger compartment during top-down driving, the majority are not. They essentially just cut the roof off a car with no thought to how that will effect the airflow. This can lead to major vortices of air, dust and bacteria whenever driven with the top down. StuRat 08:23, 4 April 2006 (UTC)

Try always wearing wrap-around sunglasses to block most of the debris from hitting your eyes. StuRat 08:28, 4 April 2006 (UTC)

"I saw a pretty woman driving on the freeway with her top down. What made it even better was that she was in a convertible, too." StuRat 08:28, 4 April 2006 (UTC)

Ship's pilothouse question[edit]

The windows of a commercial vessel's pilothouse often have a circular element inset into one or more panes of the windows of the pilothouse. This image from Google shows a pilothouse with two of these round objects visible. One in the window near the depthfinder, and one in a window in the background.

http://wildlifefotofilm.de/Pilothouse.jpg

What are these called? What are they for?

--Jeff

  • I believe they are spinning windows, for use in (very) bad rainfall. Think of them a like windscreen wipers except the wiper stays still and the window moves instead. The disc in the window rotates at high speed, and keeps clear of water & mist even in the worst weather conditions. --Bob Mellish 08:44, 1 April 2006 (UTC)
The name to search for is "clear view screen" (stub article). No wipers, just centrifugal force action. Femto 16:25, 1 April 2006 (UTC)

thermal power[edit]

what is a super thermal power station?--203.101.31.27 05:55, 1 April 2006 (UTC)

im guessing heat from the earth is used to generate steam, which turns turbines... it hink they tap into the sides of volcanos, i know theyre building a new one somewhere in the world currently 24.193.235.188 07:42, 1 April 2006 (UTC)

A quick search of Google suggests that "super thermal power" is a term used in India for large but otherwise traditional coal-fired plants. Samw 00:10, 8 April 2006 (UTC)

Circuit diagram question[edit]

I'm attempting to construct a effect pedal for a guitar. I am having difficulty reading the circuit diagram. It indicates possibly a potentiometer by indicating a resistance and having an open arrow below it. The trouble I'm having is figuring out where the arrow connects to.

The arrows are at a certain level, and may be connected to the component on their left (or right). I have never come accross this sort of circuitry notation. (Also there is a dotted line in places, I am not sure what this means.) ---Brohan 06:12, 1 April 2006 (UTC)

Pot-sch.gif

A symbol such as above, but with no connection to the wiper? Or can you find the symbol on this page. A dashed line enclosing an area of the diagram would probably mean those components are sheilded. Dashed lines as connectors would probably mean optional parts of the circuit. EricR 06:35, 1 April 2006 (UTC)
I presume I forgot to inclue a link to what I'm talking about, [2]. After a closer look I have realized that the dotted lines are nothing special, there just are several circuit diagrams, and some of them have the dotted line. My inquiry about the potentiometer connection still stands. ---Brohan 15:43, 1 April 2006 (UTC)
A pot has three terminals. Two of them are the opposite ends of the resistive track, and have a constant resistance between them that is the resistance marked on the pot. On a circuit diagram these terminals are shown as the two ends of a resistor. The third terminal, which is usually midway between the other two on the actual component, is connected inside to a thing called the wiper. This is represented by the arrow in the circuit diagram. When you turn or slide the pot, the wiper moves up and down the resistive track, so the resistance between the wiper and one end terminal goes up as the resistance between the wiper and the other end terminal goes down.
The dashed line between two pots means that they are mechanically connected, or "ganged", together, so that they are both controlled by the same knob or slider. --Heron 21:09, 1 April 2006 (UTC)


Well, there are lots of circuit diagrams at that link. Let's take the second image on the page, the first circuit diagram labelled "Basic Wah Circuit". There is just one potentiometer in the circuit, in the middle-right of the diagram, directly under the text "output". It's a 100K potentiometer, and the wiper is connected to a capacitor and then to the base of transistor Q2.
When you say "open arrow", do you mean the downward pointing open triangles? There are five in that circuit (from left to right: on one side of a 470Ω resistor, an 82K resistor, 4.7μF capacitor, the 100K potentiometer, and a 10K resistor). They indicate a connection to the ground of the circuit, they're not symbols for a potentiometer. The 0V line (negative terminal) of the power supply would also be connected to ground. --Bob Mellish 21:23, 1 April 2006 (UTC)


Thank you very much, I think my question has been answered. I was under the impression that the arrow was the symbol for a pot (The guy at my local electronics store said that it was). Infact the answer was staring right at me in Ground (electricity). It seems like a simpiler build now. Thank you very much for your help --Brohan 21:59, 1 April 2006 (UTC)

bermuda triangle[edit]

what is bermuda triangle exactly? why is everything sucked in? has any plane or ship escaped? how? do the people who have escaped have any story to tell? —This unsigned comment was added by Ac gokhale (talkcontribs) 10:02, April 1, 2006 (UTC).

We have a pretty good article on the Bermuda Triangle. Short summary - all the talk about ships and planes vanishing under mysterious circumstances, supernatural forces and whatnot is rubbish, the rate of ships and planes sinking or crashing in the Bermuda Triangle is comparable to other areas of ocean, and most incidents have perfectly mundane explanations. — QuantumEleven | (talk) 09:24, 1 April 2006 (UTC)
Lots of stuff about the bermuda triangle is myth....some planes vanished, probably crashed, over that area a long time ago and people started making up stories about it...after that a lots of disappearing cases aren't even near the bermuda triangle.... people just made up a lot of stuff.... in fact the bermuda triangle today is a busy waterway and a lots of ships pass through it everyday....even my dad's been there lots of times.... so..it means that everything doesn't get sucked in....some poor soul got a bad break a long time ago...thats it... Jayant,17 Years, Indiacontribs 14:34, 1 April 2006 (UTC)
The question was kind of funny--"has any plane or ship escaped? how? do the people who have escaped have any story to tell?" Almost all planes/ships that entered the Bermuda Triangle have "escaped". They did so using thrust. The people who escaped do have stories to tell--they can tell you how wonderful their vacation was, or how blue the Bermuda Triangle's water was, or how they didn't get sucked into the ocean, or how foolish you are in thinking they would die, or... --Bowlhover 15:30, 1 April 2006 (UTC)
Well, I sailed there in a 34-foot sailboat. The story I have to tell.. is.. well, it was pretty much like anywhere else in the Caribbean. We did run into some bad weather off Cape Lookout while heading in to Beaufort, but that was a week later and well outside the triangle. :) --BluePlatypus 23:42, 1 April 2006 (UTC)
Wow, you're lucky to be alive! Melchoir 09:33, 2 April 2006 (UTC)
It still doesn't explain the fact that when I was looking at Google Earth (this was some time ago, so the maps may have been updated), that I found a place where half of an island disappeared into a dark patch of ocean. The island? Bermuda. (Insert Twilight Zone sound effects here) --Confusing Manifestation 13:34, 2 April 2006 (UTC)

I once read a theory that beneath the seabed in some areas of the "Bermuda Triangle" is an unusually large number of pockets of gasses that occasionally get released into the atmosphere. The result is that occasionally, the atmosphere that the planes are flying through does not contain enough oxygen for the internal combustion engines of prop-planes to function properly and so they stall. Perhaps not a spooky enough explanation, but a logical theory nonetheless. Loomis51 14:23, 2 April 2006 (UTC)

That's a reference to the theory that deposits of Methane hydrate are behind some disappeareances in the Bermuda Triangle. I saw a TV documentary on it that showed a very tiny amout of methane in the air can cause airplane engines (of the type in the airplanes that went missing) to die. Also demonstated was showing how a massive release of bubbles below a ship causes it to sink because it is heavier than the foam it is now siting on. Also was proof the deposits do exist there and many other places on/under the sea floor. What is lacking is evidence that these deposits sometimes thaw out all at once (although we do know it is possible). WAS 4.250 17:34, 2 April 2006 (UTC)

  • Didn't much more vessels sink in the Great Lakes? - Mgm|(talk) 11:47, 3 April 2006 (UTC)
  • As a function of the water/air traffic, and the weather patterns in the area, the rate of 'disappearances' is no reason to think the Bermuda triangle is anything paranormal. Lots of travel + Finicky weather = Lots of losses. On the other hand, it could be due to the Methane hydrate in the ocean floor... that the Freemason's are harvesting to power their black helicopters and wage their secret war on the Elks!!!

"I lost my Bermuda shorts when swimming in Bermuda, does that count ?" StuRat 09:04, 4 April 2006 (UTC)

Serves you right for doing elephant impressions. :--) JackofOz 13:13, 6 April 2006 (UTC)

marofaut peas[edit]

Hiya.im doing a project on marofat peas for my junior cert and im dead stuck.i need to know WHY they germinate faster when soaked and i need to know A.S.A.P!please help me as i cant find any relevent info. on any site!

Try the Wikipedia article on seeds. You can find what you need in the section called "seed structure". --Bowlhover 15:42, 1 April 2006 (UTC)
Not related to the topic, but I'm glad to see you still here, Bowlhover. Hope things have improved for you. Grutness...wha? 08:33, 2 April 2006 (UTC)

I would think that sprouts, being like 90% water, would grow faster if more water is available to construct them. StuRat 08:10, 4 April 2006 (UTC)

about erp.[edit]

hi i have a project on enterprise rescurce planning (erp) and would like he softwares which come under this type of programming. —This unsigned comment was added by 210.210.63.84 (talkcontribs) .

Have you tried to type ERP to the search box, that (among other uses) leads to Enterprise resource planning that links to List of ERP vendors and also List of ERP software packages? --Jan Smolik 16:51, 1 April 2006 (UTC)

Checking Data Transfer Integrity[edit]

I recently transferred (via ethernet cable) some files between two WinXP systems and later discovered about a third was corrupted. It may be that it was corrupted to begin with or it could be that something went wrong in the transfer (either way it doesn't matter, as the data in replaceable). I'm planning on moving about 100 GB of not-so-easily-replacable data from a WinXP system to another running Fedora Core 4. Is there are a program that will check the data integrity for me, during or after the transfer? --Username132 (talk) 15:16, 1 April 2006 (UTC)

See md5sum. EricR 15:22, 1 April 2006 (UTC)
I'm doing exactly this (from WinXP to Fedora).
I'm using Unison (file synchronizer).
Unison uses the rsync algorithm.
rsync uses MD4 for the data integrity check for each file on the source.
(It would be marginally better to use md5sum, or better yet SHA-512, but I don't know how to fix it).
I can use Unison as an independent check after some other program *claims* it copied all the files.
Or I can use Unison to (efficiently) automatically detect which files are damaged or missing at the destination, and automatically re-send only those files, skipping over the good files (no matter how those good files got to the destination -- some other transfer program, or an earlier run of Unison).
--68.0.124.33 (talk) 06:44, 19 January 2008 (UTC)

Unique Extraqpolation Method?[edit]

I devised a ethod for forecasting AIDS/HIV in the UK in 1987 and have never found it in any mathematical treatise. The method is detailed in www.AIDSCJDUK.info and I would be grateful if anyone knows whether it has been published elsewhere. Edward G. Collier MBCS CITP [email removed] —This unsigned comment was added by Edwardhfd (talkcontribs) .

Robot Navigation[edit]

What is the most effective way for a robot (that has two sets of wheels allowing it to move forward and turn in its own footsteps, ie differential drive) to explore a rectangular area and find four objects (which will also be obstacles)? I had figured on some sort of a spiral that is changed to another sort of a spiral when a boundary is reached but I'm not sure if that will work perfectly.

Are you trying to get us to do your engineering design project for you...? :) — QuantumEleven | (talk) 19:38, 1 April 2006 (UTC)
Buy (or borrow) a Roomba and watch it move. That is how you want to do it. --Kainaw (talk) 21:28, 1 April 2006 (UTC)

I'm not trying to get you to solve it for me, it still has to be programmed after I do it.

Put it, wheels and all, inside a hollow sphere touching the shere only with its wheels, as the sphere bumps things it will go around them or away from them in random ways, thus exploring the available space. WAS 4.250 01:03, 2 April 2006 (UTC)

Like a hamster ball! Hee hee! - Cybergoth 04:19, 2 April 2006 (UTC)

Assuming you want to lay down a pattern, and not do a random search, I think a rectangular spiral starting from the outside of the rectangle would be most efficient in terms of fewest turns. When an obstacle is encountered, the robot should pass on the inside of the spiral. In the special case of an object in the center of the spiral, the robot can navigate either way around it. StuRat 08:05, 4 April 2006 (UTC)

Deoxygenated water[edit]

Hi, when people say that when water is boiled twice it is deoxygenated, ie. loses oxygen. So, if the molecule loses the oxygen bond, then don't you have oxygen gas and hydrogen gas left? But when it is boiled twice and supposedly "deoxygenated", then why are we still left with the water in the kettle? Thanks! Kilo-Lima|(talk) 21:43, 1 April 2006 (UTC)

I assume they're talking about lowering the concentration of dissolved O2 gas, not removing the oxygen atoms from the water molecules themselves. Melchoir 22:03, 1 April 2006 (UTC)
I boiled some water three times recently, and was left with only neutrons. They tasted horrible in my tea. --Heron 22:10, 1 April 2006 (UTC)
They mean the air dissolved in the water. As temperature increases, the amount of gas you can dissolve in liquid decreases. As you increase the temperature, entropy becomes increasingly important to the equillibrium of free gas versus gas in solution, and the free gas state (which has higher entropy) becomes favored over the dissolved gas state. --BluePlatypus 23:02, 1 April 2006 (UTC)
Yes, boiling must lower the oxygen dissolved in the water. I know this, because when I boiled the water in which my goldfish was swimming, it died. Must have been from a lack of oxygen, right ? :-) StuRat 07:58, 4 April 2006 (UTC)

Seriously everyone, where does someone look up this fact in Wikipedia? A cursory search of water and oxygen reveals nothing of the fact that warmer water has less disolved oxygen? One of my pet peeves is that there are lots of facts like this that defies the traditional encyclopedia organization structure. Samw 00:14, 8 April 2006 (UTC)

Combine the power of a search engine with Wikipedia: Search for water dissolved oxygen and the first three articles are Oxygen saturation, Winkler test for dissolved oxygen, & Oxygen depletion. The first has a description of temperature and salinity affecting the amount of oxygen. -R. S. Shaw 07:02, 8 April 2006 (UTC)

April 2[edit]

Classical Physics[edit]

Greetings, Wikipedians!

I am now in my late 20s and recently an old fascination of mine has started bubbling up. I studied mathematics at the univeristy for a while (although I eventually gave it up and studied law instead) and I consider myself fairly competent in stuff like multi-variable calculus (even though I can't possibly call myself an expert). I have recently found my love for equations have started to come back to me. Everyone has to have a hobby, right? Anyway, specifically I've been fascinated with classical physics, i can spend a good chunk of a weekend (it annyos the hell out of my fianceé) studying things like this.

I never did study physics beyond high school, but I wish to pick it up again. Can anyone recommend a good book on classical physics for me? As I said, I'm fairly competent in advanced calculus, so it doesn't have to be a beginners pop-science type of a thing, but perhaps not too advanced either. I'm tempted just to pick up an annotated version of Newton's Principia, but as I understand, it's fairly archaic in it's mathematics and also fairly dense. Any recommendations?

Cheers!
Oscar

Young's University Physics, or Benson's book by the same name seem popular to me. Both are introductory-level university texts that cover the basics of the whole field and are mostly classical, except for the obligatory chapter introducing the basics of quantum stuff. Neither of them require much more than some calculus skills. --BluePlatypus 03:28, 2 April 2006 (UTC)
How about The Feynman Lectures on Physics? —Keenan Pepper 03:32, 2 April 2006 (UTC)
I echo the Feynman lectures - they cover an incredibly broad range of topics, and are very well written. Admittedly, the maths doesn't get an awful lot more complex than second-year calculus, but I don't think it needs to be, either, if you're just starting out. — QuantumEleven | (talk) 09:40, 2 April 2006 (UTC)
I recommend you give your fiancee a massage while you listen to the Feynman Lectures on tape. GangofOne 07:36, 2 April 2006 (UTC)
Depending on your circumstances, H L Mencken's comment on physics may or may not be relevant to you and your fiancé: "It is now quite lawful for a Catholic woman to avoid pregancy by a resort to mathematics, though she is still forbidden to resort to physics and chemistry". :--) JackofOz 08:37, 2 April 2006 (UTC)
It's not clear how the mathematical contraception works, (maybe he means the "rhythm method"?), but what I was getting at is you'll have a better life if you can get your spouse involved in your hobbies, maybe she'll enjoy the tapes so much she'll become intersested in classical physics, and more specifically, classical physiques. --GangofOne 07:47, 4 April 2006 (UTC)
On a slightly separate note (I can't really recommend a good physics book, unless you're into Atmospheric Dynamics, in which case I'd recommend An Introduction to Dynamic Meteorology by J.R. Holton), have you considered becoming a Wikipedian yourself? We always need eager, well-rounded editors, and believe me when I tell you that the experience allows you to learn all sorts of interesting and eclectic information. EWS23 | (Leave me a message!) 08:43, 2 April 2006 (UTC)

I appreciate your fascination, since I share it also upon some other degree, but though classical physics remains a highly motivating subject, one must realize that the field has moved on also to some other, let be said, more esoteric fields that the masters of the old physics would have never dreamt of. Upon the coming of the New Age the philosophy of physics is also changing from reductionism to synchronicity. I'm afraid I am not helpful enough to recommend you books on classical physics (unless, of course, you have also developed an interest in Quantum Mechanics, in which case I recommend Thirty Years that Shook Physics by George Gamow), I am only able to suggest that in developing such an admirable interest in the field, you may also be interested to extend your knowledge into the more recent innovations of the area that has changed our thinking since Newton. But of course, all this is entirely supplementary and a grounding knowledge in classical physics is always good before you rush on to something else. Luthinya 09:48, 9 April 2006 (UTC)

Graphics Card/NIC combo in Fedora Core 4[edit]

I have a Cirrus Logic GD 5446 graphics card with built-in NIC. Although the graphic card part is detected and works on my Fedora Core 4 system, the network card is not recognised. When I plug in an ethernet cable connected to my modem, the green light (connection) comes on and the amber light (activity) flashes but according to Hardware Browser, it's doesn't come under 'Network devices'. Would installing a driver resolve this issue? There's one here but it doesn't specify an operating system. --Username132 (talk) 01:15, 2 April 2006 (UTC)

Is KDE installed?[edit]

It typed "yum install KDE" at the terminal in Fedora Core 4 but it didn't seem to be installing anything.

Here's how it went down;

[root@localhost numlockx-1.1]# yum install kde
Setting up Install Process
Setting up repositories
updates-released          100% |=========================|  951 B    00:00
extras                    100% |=========================| 1.1 kB    00:00
http://ftp.chg.ru/pub/Linux/fedora/core/4/i386/os/repodata/repomd.xml: [Errno 4] IOError: HTTP Error 404: Transfer-Encoding: chunked
Date: Sun, 02 Apr 2006 00:46:26 GMT
Content-Type: text/html; charset=iso-8859-1
Server: Apache/1.3.33 (Unix)
Trying other mirror.
base                      100% |=========================| 1.1 kB    00:00
Reading repository metadata in from local files
Parsing package install arguments
No Match for argument: kde
Nothing to do
[root@localhost numlockx-1.1]# start kde
-bash: start: command not found
[root@localhost numlockx-1.1]# kde
-bash: kde: command not found
[root@localhost numlockx-1.1]# run kde
-bash: run: command not found
[root@localhost numlockx-1.1]# yum install kde
Setting up Install Process
Setting up repositories
Reading repository metadata in from local files
Parsing package install arguments
No Match for argument: kde
Nothing to do

How do I know if KDE is already installed? And if it is, how do I start it? If I started KDE, would it close down Gnome? My computer couldn't run two GUIs at the same time very well.

--Username132 (talk) 01:20, 2 April 2006 (UTC)

Computers aren't smart enough to guess at what you want. Try "yum list | grep kde" to see what packages have "kde" in the name. Then, install the whole package name, such as "yum install kdebase". As you can see from the message you received, there is no packaged names "kde". --Kainaw (talk) 01:34, 2 April 2006 (UTC)
I see, thanks :). It could have been more clear about things... how come "yum list | grep opera" doesn't produce any results, when I know "yum install opera" does something (I think Opera web browser). --Username132 (talk) 04:57, 2 April 2006 (UTC)
Unless you've added repositories to the generic Fedora repositories, Opera is not included. Fedora only includes free, open-source programs. Opera is free now, but used to require payment (yes, there was a free preview version, but that isn't the point). Also, Opera is not open-source. Finally, depending on your version of grep, you may want to include the "-i" option to turn of case sensitivity, such as "yum list | grep -i SDL" --Kainaw (talk) 20:23, 2 April 2006 (UTC)
Ah, thanks for the tip! --Username132 (talk) 00:33, 4 April 2006 (UTC)

chloroform[edit]

What does chloroform react with to make someone unconscious?

Scientific how does it?

Chloroform is a general anaesthetic. According to the Wikipedia article on general anaesthetic:
"It is now known that general anaesthetics act on the central nervous system by modifying the electrical activity of neurons at a molecular level by modifying the function of ion channels. This may occur by anaesthetic molecules binding directly to ion channels or by their disrupting the function of molecules that maintain ion channels." --Bowlhover 05:07, 2 April 2006 (UTC)
Here's an article: http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1328629
Chloroform increases the permeability of the cell membrane to ions, which makes it harder to build up an action potential. —Keenan Pepper 14:19, 2 April 2006 (UTC)

Chloroform cannot be a true general anaesthetic, becuase if it were, it would paralyze the all the body's involuntary autonomous systems. For example, when a true general anaesthetic is used, the lungs no longer function and a breathing machine is required to keep the patient alive. From what I understand of chloroform, the subject may be "knocked out" but he or she is still able to breath...etc...Loomis51 21:44, 6 April 2006 (UTC)

Paint thinner chemical[edit]

I'm having trouble finding out the name of a chemical that is in some paint thinners and it becomes carbon monoxide when inhaled. Any guesses? KeeganB

When fuels are burnt with insufficient amounts of oxygen, incomplete combustion can occur. Instead of the normal CO2, some CO is also produced. Some paint thinners contain (surprise!) isopropyl alcohol, also known as isopropanol, which can decompose and release CO gas. Isopropyl 05:46, 2 April 2006 (UTC)

I forgot to mention that this chemical is metabolized by the body and it becomes carbon monoxide because of the metabolization. KeeganB

Are you sure it's carbon monoxide that it gets metabolized to? Toluene, the chemical that gives paint thinner its characteristic smell, is rather toxic; it breaks down into epoxide radicals in your body. Other than that, I have no idea what the chemical could be. Perhaps you could take a look at the packaging and look up the chemicals listed in the warnings? Isopropyl 06:29, 2 April 2006 (UTC)
Paint thinners are generally a mixture of Hexanes (Toluene), Isopropyl, or Acetone. Really depending on the type of paint thinner you are purchasing. I don't know of any of these that would be metabolised by the body readily, more likely you're going to exhale the fumes. If any it would be isopropyl, and it's still not advisable to inhale or ingest it. This is why you wear a face mask and use paint thinners in well ventilated areas.--Tollwutig 17:53, 3 April 2006 (UTC)

SSH, PGP and CACert[edit]

I have three key-pairs: one for SSH, one for PGP and a "client certificate" from CACert. Don't all === these serve the same purpose? Is it possible to use the same key-pair for all three? —Masatran 06:52, 2 April 2006 (UTC)

Typically, no. These (as far as I know) use different encryption algorithms, and even if you could have, say, the same private key for all of them, the public keys would differ. But why do you care? You'll certainly never interact with your own SSH key (sshd is all that touches it), and a certificate is just a statement made and signed by the certificate authority that identifies you. Neither of those will involve you very often.
To answer your other question: no, these are for different purposes. The SSH key is used to prove to SSH clients that your server is the same server they've used before and not an impostor. The PGP key is used by others to make messages readable only by you and by you to prove that you wrote something. The certificate is again some identification of you (perhaps your real name and a domain name of yours) signed by someone that you expect others to recognize and trust to make such identifications. --Tardis 18:47, 5 April 2006 (UTC)

--68.98.102.247 (talk) 03:33, 7 November 2013 (UTC) meetings for the hours/ of total for moeny so putt some them for the hours $______________

There's no reason why, in a theoretical sense, you couldn't use a single public-private key pair for different applications. It's a question of the software supporting it. For example, I seem to recall that some SSH implementations allow the use of X.509 certs, and Italic textyou can extend OpenSSH to allow the use of PGP keys[3]. — Matt Crypto 19:26, 5 April 2006 (UTC)
OK, after some research, I see that as least SSH and PGP are compatible through RSA and DSA. I thought PGP's encryption was some other variety. But I can't imagine that PGP could work together with X.509, unless what the certificate was for was the public key...? --Tardis 21:19, 5 April 2006 (UTC)
X.509 certificates certify that a public key belongs to some entity, so there's no reason, in principle, why an OpenPGP application couldn't use a key from an X.509 certificate. It seems that PGPi supports X.509 certs[4], for example. For encrypting and/or signing messages, a key is just a key, and the differences are superficial ===

--68.98.102.247 (talk) 03:33, 7 November 2013 (UTC)(file formats etc). The big issue is the PKI, i.e., how you can reliably find out someone's public key without being spoofed: web of trust (OpenPGP) vs a CA (X.509) vs, er, ad hoc verification (or none!) (SSH). — Matt Crypto 12:45, 7 April 2006 (UTC)

Satellites[edit]

Can you see Satellites in night with nakes eyes from the ground?

Yes! But I've never seen one. This link tells you how to do it, as does this one. And this one tells you about the hobby. Hope this helps. Kilo-Lima|(talk) 11:25, 2 April 2006 (UTC)
Sure. I see them often, though. They're small and star-like, except they move at a constant speed across the sky. ☢ Ҡiff 19:51, 2 April 2006 (UTC)
Iiridium flares, which are generated by the Iridium satellites' main mission antennas, are extremely bright (the brightest flares can reach magnitude -8, 28 times Venus's maximum brightness). Heavens Above provides predictions for iridum flares and HST/Envisat/ISS passes. Be sure to enter the latitude, longitude, and elevation of your house, not your city--the coordinates have to be very accurate. --Bowlhover 20:16, 2 April 2006 (UTC)
They're not particularly difficult to spot - look up just after sunset or just before sunrise (the satellite above you needs to be illuminated while you need to be in darkness). If you see a star moving across the sky rapidly without blinking (if it's blinking, it's probably an airplane), you've just spotted a satellite. When I say "rapid" I don't mean rapid like a meteor (gone in about a second), but fast enough that it's easy to see it moving - it takes about a minute or two to cross the entire sky. Happy stargazing! — QuantumEleven | (talk) 21:31, 2 April 2006 (UTC)
The ISS is particularly bright - about as bright as one of the brighter planets (say, Jupiter) I second Bowlhover's comment about Heaven's Above - it;'s a very good website if you want to find out when bright satellites will be overhead. Grutness...wha? 06:58, 3 April 2006 (UTC)
You didn't exclude natural satellites, so I would add that the Moon is occasionally visible. StuRat 19:26, 3 April 2006 (UTC)
A satellite in the sky often looks like an aircraft since they have a similar apparent angular motion. A commercial jet might fly 10 km high (about 30,000 feet) and travel at a speed of 1000 km per hour (about 600 mph, or 0.3 km/s). A low Earth orbit (LEO) satellite is about 30 times higher and travels about 30 times faster, so the motion looks almost the same (300 km altitude, 8 km/s). For an aircraft, you are usually seeing the lights - if it blinks, you know it is an aircraft. But you can only see a spacecraft when it is still in sunlight are you are in shadow, after sunset or before sunrise. Sometimes you can see the spacecraft enter the Earth's shadow, turning red and then fading quickly. elee 16:50, 6 April 2006 (UTC)

why is thepiratebay.org still up?[edit]

I would have thought that the RIAA/MPAA/(insert name here) would have shut it down ages ago. After all, how much closer to a blatant copyvio can you get?--Frenchman113 16:05, 2 April 2006 (UTC)

Well, IANAL, but they do have a point that "Only torrent files are saved at the server. That means no copyrighted and/or illegal material are stored by us...". Also, it's possible the servers are in a country where the RIAA and MPAA have no power. Anyone know where the servers actually are? —Keenan Pepper 16:37, 2 April 2006 (UTC)
whois -H thepiratebay.org turns up registration in Stockholm, Sweden. Isopropyl 16:46, 2 April 2006 (UTC)
Because they're not violating copyright law. They're not actually distributing the copyrighted material themselves. Merely linking to it isn't illegal. Sweden isn't the only country where this is probably the case, so the more pertinent question is perhaps why the Swedes are less prone to fold to empty legal threats? --BluePlatypus 17:27, 2 April 2006 (UTC)
The Pirate Bay are frequently contacted by individuals and organizations requesting removal of copyrighted materials from their site. They (and their lawyers) find this extremely humorous, and post the correspondence on their site at the URI http://thepiratebay.org/legal (I think that's the right address). --WhiteDragon 19:20, 4 April 2006 (UTC)
Almost - it's http://thepiratebay.org/legal.php. -- Marcika 21:48, 5 April 2006 (UTC)

Why do voltage regulators come as modules?[edit]

I was wondering why the voltage regulator on a server processor board comes as a module (VRM) instead of being soldered in place like I imagine it is on my PC motherboard. Are they prone to failure? --Username132 (talk) 14:31, 2 April 2006 (UTC)

The answer is at voltage regulator module. --Heron 18:52, 2 April 2006 (UTC)
So if it comes as a separate module, it must be fixed to a specific voltage? --Username132 (talk) 22:25, 2 April 2006 (UTC)
It has a lot to do with costs. With a $5k-$30k server you're more likely to keep it a long time and upgrade processors instead of replacing the unit. If you are in the IT industry you know processor generations are about 6 months to 1 year. With a PC a system board usually only costs between $100-$300, while a server it can cost between $1000-$3000 just for the system board alone.

Now say you have a server you wish to upgrade the processors. Which is cheaper, to replace a VRM or an entire system board?--Tollwutig 16:23, 3 April 2006 (UTC)

Topic Suggestions[edit]

I need some topic ideas for my IB Extended Essay maybe you guys could help. The subject I want to do is in computer science. I have some knowledge of neural networks, genetic programing (algorithms), economics (could be relevant? modeling?) and cryptography (along with misc. computing knowledge). The essay must have an original thesis that sets out to prove somthing non-trivial (someone else is doing stuff involving computational ecomplexity). Any suggestions? (By the way: the project cannot be writing a program to do somthing (although that could be part of the essay)). Leonardo 16:17, 2 April 2006 (UTC)

Define the least intelligent worm that when let loose on the internet increases its intelligence without limit, given enough time and no serious eradication effort. The minimum computational skill set for unbounded automated learning. WAS 4.250 17:52, 2 April 2006 (UTC)

How about building elementary logic gates with cells via DNA transcription? That's what I'm studying right now, and it's kind of interesting, I guess. Isopropyl 17:56, 2 April 2006 (UTC)
An economics topic which interests me is ideal firm size. A program which accepts firm size and growth rates as input could calculate the ideal firm size for the maximum growth rate in several industries, study how the ideal firm size has changed in each industry over time, etc. Note that you would need to include companies which have declared bankruptcy, or you would introduce bias towards small firms. StuRat 19:16, 3 April 2006 (UTC)
Hmmm, I think that's too economic and not computer science enough. As to isopropyl, that's an idea, but it requires more biology than I know (I guess I could try to pick it up). And as to WAS 4.250...Cool idea conceptually, but yeah that's beyond me. I wouldn't even know where to begin. I might do something with intelligent malware though. Hm...cryptovirology? Anyone have any topic ideas involving that? Leonardo 21:11, 4 April 2006 (UTC)

good largescale spyware removal utility? for free?[edit]

suggestions?--172.153.199.58 17:13, 2 April 2006 (UTC)

What do you mean by "large scale"? If you're looking for enterprise quality software you'll have to pay for it. The most popular & most frequently recommended consumer freebee apps are LavaSoft's AdAware, Spybot, and HiJackThis. Using all three provides a rather comprehensive solution. You can download these or search for others at majorgeeks.com. Also, take a class on editing the Windows registry if you use Windows. There are a number of free registry utilities but be careful if you don't know what you're doing. Registry errors can make your system nonfunctional. Ande B 22:56, 2 April 2006 (UTC)
Adaware is a good antispyware, but what do you mean by largescale?--Frenchman113 22:59, 2 April 2006 (UTC)
A good large scale spyware removal tool? None really get rid of all spyware as often you need to be in Safe Mode and do registry edits to get rid of the worst offenders. The best means is to prevent spyware by setting your firewall to block all traffic on port 80. Its the most effective preventative measure I have found.--Tollwutig 16:16, 3 April 2006 (UTC)
Blocking all ports or physically disconnecting your computer from the network works even better. --Optichan 16:33, 4 April 2006 (UTC)

Integer precision[edit]

  1. In C++, what is the most portable way to get an integer type guaranteed to have at least n bits of precision?
  2. Is there any portable way to get an integer type that not only has exactly n bits of precision, but also wraps around modulo 2n on overflow? For example, an 8-bit type in which 100 + 200 == 44. —Keenan Pepper 17:14, 2 April 2006 (UTC)
No. You will want to use sizeof to detect the size of the short an long types and then manipulate them as necessary. With 64-bit systems becoming popular, this is a real problem right now. --Kainaw (talk) 22:22, 2 April 2006 (UTC)
For number 1, you could try GMP, which is fairly portable (certainly *nix and Windows) and has a C++ interface (it is C internally.) For number 2, that is what happens with the built-in integer types in C and C++, the problem is that the sizes of the various types (char, short int, int, long int) are not defined in the specs. -- AJR | Talk 22:36, 2 April 2006 (UTC)
For small values of n, is it possible to use
typedef struct { int eightBit : 8; } number;
number a.eightBit = 257; // Stores 1 in a.eightBit Ojw 23:11, 2 April 2006 (UTC)

Okay, I didn't think #2 was possible. For #1, I was looking for something along the lines of stdint.h for C. I notice there's no <cstdint> in the standard C++ library... —Keenan Pepper 23:35, 2 April 2006 (UTC)

<cstdint> will most likely appear in the next C++ standard update, but because of the glacial pace of the international standards process, you might have to do with <boost/cstdint.hpp> available at [[5]]. If you can limit yourself to Unix, the Single Unix Specification defines a similar <inttypes.h>, not to be confused with the C99 inttypes.h. 84.239.128.9 19:02, 3 April 2006 (UTC)

electronic marketplace[edit]

describe an electronic marketplace in which disc technology combines with the internet to provide information and services to consumers

Do your own homework. --Bowlhover 19:27, 2 April 2006 (UTC)
Pornography!! Tzarius 09:11, 3 April 2006 (UTC)
Yeah I'd say pr0n is the major use of this.. also this stinks of a homework question.--Tollwutig 16:12, 3 April 2006 (UTC)

Handwashing[edit]

A friend told me that most soaps advertised as anti-bacterial actually can increase the amount of bacteria present on the hands. Is this true and why would this occur?

AO24 21:52, 2 April 2006 (UTC)

Most likely, he was referring to the growth in super-resistant bacteria. By killing common bacteria quickly, only the resistant bacteria remains. Over time, the resistant bacteria will evolve into super-resistant bacteria that is completely immune to our common household anti-bacterial soaps, cleaners, and air sprays. All-in-all, the "anti-bacterial" craze can be seen as doing more harm than good. Not all bacteria will harm you. Many forms of bacteria help you. Killing the good ones is not a healthy thing to do. Making the bad ones resistant is not a healthy thing to do. The next time you see something that kills 99.99% of all bacteria, remember that it may only leave that 0.01% that can actually cause you harm. --Kainaw (talk) 22:11, 2 April 2006 (UTC)


(After edit conflict)Your friend has, I think, gotten something confused, but there's a kernel of truth behind it. It's not that washing with antibacterial soap leads to more bacteria, but rather that it can lead to production of superbugs --bacteria that are resistant to normal treatment, and also kills off the helpful bacteria. It works like this: you wash with a soap containing a particular antibacterial agent. It kills 99% of the bacteria that are susceptible to it. The one percent then breed back to high numbers, but because they are the ones who survived the last treatment, they naturally have some defense to the agent you used which they pass on to their progeny. You use the same soap with the same agent again. This time, because the generation that are left are more resistant, only 70% die. They breed back to level. This cycle continues until you have bacteria that are very resistent to the agent in the soap. This is how evolution works, and is the same reason we have developed so many antibiotic resistant strains of microbes (which has been greatly increased by blanket prescribing of antibiotics where it is not necessary, as well as people's tendency to not take the full antibiotic series). --Fuhghettaboutit 22:12, 2 April 2006 (UTC)
Not necessarily. If the "antibacterial" agent is just a disinfectant and not an antibiotic, then this shouldn't breed antibiotic resistance. People who use antibacterial soap might not wash their hands as carefully, so they don't end up killing as much bacteria on their hands as someone doing a proper hand-wash with regular detergent soap. - Cybergoth 02:13, 3 April 2006 (UTC)
Even disinfectants can lead to resistant bacteria. Bacteria can adapt to chemicals in the environment as well as antibiotics. --Tollwutig 16:10, 3 April 2006 (UTC)

Killing off the good bacteria (which control the bad bacteria) could allow the bad bacteria to spread uncontrolled. I'm not aware of this being a problem on hands, but medicated douches can cause this very problem in the female reproductive tract. StuRat 19:05, 3 April 2006 (UTC)

April 3[edit]

Computer Technology-Measurement of the Capacity of Hard Disk Drive LinkFA-star.png[edit]

Someone has just asked me about the capacity of my PC's hard disk drive.I have tried checking all manuals that were delivered with my PC but I could not find this information.Maybe it's because I do not know where to look for this information and also that I do not know how the capacity of a hard disk is measured.Internet research about my PC brought out this, "Storage  :40/80/120/160/200/GB ATA/100 hard disk drive".This confused me even further.Is my answer found in any of the figures quoted above or I have to look elswhere?

If you're on a Windows XP PC, click "Start" Then "My Computer" then "Local Disk (C:)" the details in the lower left will tell you the storage of your hard disk drive ("Total Size"). If you did your research right then that number will be around 40/80/120/160/200/GB. See Gigabyte for how the storage capacity of a hard disk is measured. -Snpoj 01:36, 3 April 2006 (UTC)
If you're using Linux, run fdisk as superuser and type "p" when it asks you for a command. Also, try checking the sides of your computer. Some computers have general system information printed there. --Bowlhover 04:59, 3 April 2006 (UTC)
If you don't have root privileges, try "df -h" though you may have to do some simple addition to get the answer. --Bth 09:26, 3 April 2006 (UTC)
Note that "df -h" is only useful for finding out the disk size when:
(a) There is no disk space that is not part of a partition, and
(b) All of the partitions are mounted. --Bowlhover 04:21, 4 April 2006 (UTC)
Note though that you can type fdisk -l to get information about the partitions without starting the fdisk program interactively. (There's a similar option to the DOS fdisk program, fdisk /status I think.) – b_jonas 14:18, 4 April 2006 (UTC)

just a note, 40/80/120/160/200/GB means 40 or 80 or 120 or 160 or 200 gigabytes. your computer could be near any of these values. if you are still having difficulty, ask your local 14 year old. good luck

Another note, harddisk manufacturers use a different standard from most OS's to calculate size, and thus there will almost certainly not be a round number displayed. Manufacturer uses XX * 10^9 as a standard for gigabytes, while Windows uses XX * 2^30 for gigabyte. The first is about 6% smaller then the latter. SanderJK 09:30, 3 April 2006 (UTC)

Try the above suggestions first.. But the most reliable place to find your drive size is on the sticker on your hard drive itself. It's probably deep inside your computer though so you might not want to open it up to look. Also when you first start up your computer the drive size might be incorporated into the name of your hard drive in the POST start up screen. It's also difficult to notice or recognise. Again, try the above suggestions first :) —Pengo 10:11, 10 April 2006 (UTC)

UFO sightings[edit]

Yesterday and the day before yesterday, I spotted 3 UFOs. The first two were patches of dim, white light (by the way, there were thin clouds when I saw this), about 1 degree large, moving quickly across the sky. "Quickly", in this case, means "faster than the high-altitude airplanes that leave visible trails, about the speed of the airplanes that don't leave trails and whose blinking lights can be seen, but faster than satellites". The third UFO was very bright, certainly much brighter than the magnitude -5 iridium flare I saw, and it travelled from the triangle in Leo to the constellation Cancer in little less than a second. It simply vanished after reaching Cancer. (Note: I couldn't see any of Cancer's stars, but the bright Saturn marked its position).

Any ideas about what the three UFOs I saw were? Thanks. --Bowlhover 05:14, 3 April 2006 (UTC)

The third one brings to mind a meteor, perhaps a sporadic Leonid. –Mysid 07:19, 3 April 2006 (UTC)
If you don't know what it was, how do you know how big it was? And if you don't know how big it was, how do you estimate how fast it was? --BluePlatypus 13:39, 3 April 2006 (UTC)
Also, the ufo guys used some device that kept photons for reaching his eye, so Bowlhover could estimate that they were farther. --DLL 18:57, 3 April 2006 (UTC)
I don't know how big the UFOs were, or how fast they were moving. However, I do know how big they appeared to be, and how fast they appeared to move. Sorry for the confusion--when I said "faster than the high-altitude airplanes", I was refering to the apparent speed, not the absolute speed.
I originally thought that the third UFO was a meteor, too. However, the Wikipedia article on meteors said that the British Astronomical Association defined fireballs as meteors that are magnitude -5 or brighter, implying that fireballs are rare. There was no meteor shower yesterday, I had been outside for only 3 hours when I saw the UFO, and the UFO was much brighter than magnitude -5. Could I really have been that lucky? --Bowlhover 19:43, 3 April 2006 (UTC)
Yes. In any case, keep good records. If there were actually physical objects, then others may see them. If you don't keep records of exact time and position in the sky, etc, it's just hearsay. If there is an actual phenomenon, then over time correlations between various records will reveal a pattern. GangofOne 00:45, 4 April 2006 (UTC)
I agree, but whether I keep accurate records or not will not influence whether my claims are hearsay. They're hearsay no matter what. Also, I know that to many people, "UFO" is a synonym for "alien spacecraft". I don't think the UFOs I saw were alien spacecraft--they were simply objects I could not identify at the time (although I strongly suspected the third one to be a meteor--I still do). --Bowlhover 04:17, 4 April 2006 (UTC)
In a legal sense, if you write observations down in a notebook at the time they occur, they will have more evidentiary status in a court of law or scientific dispute, as time passes, than if you say, 'in the beginning of March 2006 I saw some lights in the sky in an easterly direction', which is worthless. GangofOne 07:27, 4 April 2006 (UTC)
If the third object looked like a bright meteor to you, it seems likely that it was. According to the American Meteor Society FAQ, fireballs of magnitude -4 can be expected about once in every 20 hours of observing and magnitude -6 or better for every 200 hours. So maybe you DID just get lucky. It's hard to guess what the first two objects (patches of dim white light) were from the description alone. Is it possible that they could have been searchlights reflecting off the thin clouds that you mentioned were present? --DannyZ 07:14, 5 April 2006 (UTC)

Density of argon[edit]

Anyone got the density of solid argon at freezing point (84K IIRC) handy? -- Миборовский U|T|C|M|E|Chugoku Banzai! 05:36, 3 April 2006 (UTC)

This page gives the density as 1636 kg/m^3, though doesn't state what temperature and pressure that's measured at. --Bth 07:16, 3 April 2006 (UTC)
This has the most information I can find and gives the density of 535.6 kg/m^3 at Argon's critical point of -122.3 C Nothing I can find shows much information about Argon's solid form of -199.3C Bth reported the Density of the Gas at 0C. --Tollwutig 16:05, 3 April 2006 (UTC)
I used to have density charts for all the phases of the various chemical elements. But alas, now they argon. StuRat 07:49, 4 April 2006 (UTC)
That's very unhelpful of that page to give it as the "solid" density, then. Thanks for the correction, though. --Bth 08:54, 4 April 2006 (UTC)
Kaye and Laby to the rescue! (ish) They give the density as 1656 kg/m^3 at 40K (and standard pressure if I'm reading them right, so it should be in the solid form), but that seems suspiciously similar to the gas-at-zero-celsius if Tollwutig is right. They do give the melting point of 84K that Miborovsky remembered. --Bth 12:41, 5 April 2006 (UTC)

Synesthesia/Light Organ[edit]

Hello, I recently read an article, but I cannot find it again. It pertained in some way to synaesthesia, among other things. It mentioned a composer, possibly Scriabin, and how he used a light organ, as well as how he experimented on having smells waft through the audience. The article also stated that he wanted his magnum opus to be performed at the base of a mountain. I don't believe synthesthia was the main focus of the article. It had something to do with sound I think, and I remember there were a few charts on it. There was perhaps some kind of system, and its inventor had a name that was a double entendre, its other meaning being a part of the brain, I believe. Is there an author out there who knows what I speak of? Thank you, KeeserSilver

See Clavier à lumières. –Mysid 07:44, 3 April 2006 (UTC)

Words losing all meaning[edit]

Why is that when you repeat a word several times it eventually "loses all meaning", as in the word appears wierd and you see it differently ts hard to describe buti hope someone knows what i mean. Thanks Kingstonjr 14:49, 3 April 2006 (UTC)

I know what you mean (try typing or writing a word forty or fifty times, or staring at a page of a book with the same word repeated over and over on the whole page - I think this was done in Microserfs) - but I don't know if there's a word for it. I couldn't tell you the cause, either. Proto||type 15:31, 3 April 2006 (UTC)
yea i know exactly what you mean, it is hard to explain i dont know what causes that though. modesty 16:22, 3 April 2006 (UTC)

Let me propose a theory: Our minds are designed to only notice new or changing things. For example, if you look at a scene, your attention will immediately be drawn to the moving object and will virtually ignore the rest. A repeated word gets the same treatment. You should keep this in mind and avoid sentences like "I excitedly saw how excited they were due to the excitement of the current situation and the exciting day in general". A better sentence would be "I was happy when I saw how glad they were due the excitement of the current situation and the interesting day in general". StuRat 18:41, 3 April 2006 (UTC)

I found an interesting hypothesis on some random web site regarding this: Any word in any lexicon will start to sound funny if you repeat it aloud enough times. That's because after hearing a word x times, your mind starts to realize that there's no context associated with it, and therefore it lacks the meaning(s) it would have under normal circumstances. Your mind starts to analyze the sounds that make up the word, and the actions that are being taken by your vocal cords, tongue, teeth and nasal passages to create the sounds. Makes sense, but who knows? – ClockworkSoul 00:59, 4 April 2006 (UTC)
That "dynamic change" theory explains a lot of things, such as why we feel dizzy long after we (and the little doodad in the inner ear) have stopped spinning, and various visual illusions (especially the one with the ring of pink dots and the phantom green dot). Tzarius 08:29, 4 April 2006 (UTC)

I looked for some scientific reasearch on this a while back, and I found that the term for the phenomena is "auditory habituation", where the repeated words undergo a "verbal transformation", so you may want to use those as search keywords if you plan to do more reasearch on the subject. You could also have a look at this paper from APA Online, however you have to pay to view it unless you college/school library has a subscription. Hope this helps. --Aramգուտանգ 05:49, 5 April 2006 (UTC)

This effect is generally called semantic satiation ("verbal transformation" is hearing other words in a repeated stimulus). – 74  19:53, 12 March 2009 (UTC)

Ancient puzzle[edit]

When I was a kid I read the following (paraphrased) puzzle in a book:

A man wants to cross a bridge that can support 10 lbs. more than he weighs. He is carrying (3) balls that weigh 5 lbs. each. How can he cross the bridge without collapsing it?

The answer was to juggle the balls as he crosses the bridge. Ostensibly he would be carrying only (2) balls at a time, as one would always be in the air. However, the force necessary to toss the third ball into the air would create additional downward force that I believe would be enough to collapse the bridge. Does it matter to the bridge that the balls are being juggled?


hrmm, you also have to think when he catches a five pound ball (5 pound balls seem like a lot to juggle btw) its going to produce a force stronger than 5 pounds from it falling a distance of 1-2 feet or so. i think for this to even consider to be workable hes going to have to have a maximum of 1 ball on him at any given time modesty 16:26, 3 April 2006 (UTC)
Why doesn't he just cross the bridge with two balls, go back and get the third one? User:Zoe|(talk) 16:33, 3 April 2006 (UTC)
Because monkeys will steal the third ball if he leaves it behind?
lol yea, and really if the bridge can only support EXACTLY 10 pounds over his weight, will it break if he steps too hard? the whole question is dumb i dont think weight limits work that way modesty 18:08, 3 April 2006 (UTC)

1) Kill all the monkeys on this side of the bridge.

2) Cross the bridge without your balls.

3) Kill all the monkeys on the other side of the bridge.

4) Go back over the bridge.

5) Toss your balls over.

6) Cross the bridge yourself and reward yourself with a nice monkey brain stew. StuRat 18:30, 3 April 2006 (UTC)

Think of holding a single ball as accelating it at 1 g. To throw the ball the max acceleration w/o exceeding the limit of the bridge would be 2g. Say you take 1 second to throw the ball. That's 2g of acceleration for 1s, 1s for the ball to reach it's apex, 1s to fall back to your hand and 1s to decelerate the ball at 2g. Two seconds required to throw and catch gains you two seconds of flight time for the ball.
To get across, raise the side of the bridge you are on, using rocks, dead monkeys etc., then roll across (see inclined plane.) EricR 20:03, 3 April 2006 (UTC)
So essentially its Myth:busted on the fact that you cannot gain any legitmate force-over-time by juggling (other than the delight of onlookers). I agree that the premise is preposterous in a real world setting amyway since forces from footsteps, wind, evil monkeys, etc would combine and create a great likelihood that the bridge will fall regardless of your juggling antics. --Jmeden2000 20:36, 3 April 2006 (UTC)
Free body diagram. Peter Grey 06:18, 7 April 2006 (UTC)

dual booting linux/windows[edit]

hey i currently have windows xp running on a 60 gig hd. i want to install linux dual boot for a number of reasons. however i read that i would have to partition this hard drive and split it between the two OS. i have been meaning to get a new hard drive anyway for additional storage and to not risk losing my old hard drive data in the process. so my questions are: | 1. if i do get a second hard drive thats say 120 gigs or so, can i give linux 60 gigs of that and windows another 60? | 2. how would i go about doing that- the red hat site lists a program called partitioner or something | 3. will i be able to access files(mp3s) stored on my current hard drive(which i guess has a windows file management system) in linux? | 4. lastly if you recently bought or know a good quality quiet hard drive that holds 100-200 gigs for an ok price give me a link:D cheers- modesty 16:32, 3 April 2006 (UTC)

  1. Yes.
  2. The installer for your chosen Linux distribution will let you partition your hard drive. By only allocating 60GB in that program, you can then choose to use the remaining space to create another partition in Windows using Disk Management under Control Panel -> Administrative utilities (I think that's the English name for it).
  3. Yes, but you may need to upgrade your Linux kernel to be able to read NTFS partitions. This varies between distributions, and *may* require you to re-compile a new kernel yourself. If you also want to access the Linux disk from Windows, you should use ext2 or ext3 for your Linux partition and install a file system driver for XP (such as Ext2fsd). Then, you can assign a drive letter using Disk Management. --Pidgeot (t) (c) (e) 16:55, 3 April 2006 (UTC)
Don't tell newbies to compile their own kernels. That's just cruel.
I didn't say he should compile a new kernel, I said that depending on the distribution he chooses, that may end up being necessary. With that knowledge, he can go look for one that DOES support it without recompiling. --Pidgeot (t) (c) (e) 18:07, 3 April 2006 (UTC)
1. You could do that, but I don't see why you would want to. Personally, I would format most of the new disk as something both Windows and Linux can access, like FAT.
3. It depends which "windows file management system" it is. If it's FAT, Linux will have no problem with it. If it's NTFS, you might have some problems. I know there's a native Linux driver for NTFS that can read files, but I think the write support is still buggy. Reverse engineering is hard.
4. I bought a Seagate 120G for like $50 which has been running fine for a good while now. —Keenan Pepper 17:04, 3 April 2006 (UTC)
As a side note always install Windows first and Linux second, as the Windows installer is ALWAYS set to rewrite the boot sector of the disk. --Tollwutig 17:59, 3 April 2006 (UTC)
thanks, i just got this computer in december and its a dell e510... dunno if its fat or nts (probably whichever is newer?) with xp media center edition, and im installing fedora core 5... this will be cool if it works out as easily as you both have made it sound... thanks again, fast replies 129.32.93.17 18:02, 3 April 2006 (UTC)
XP uses NTFS by default unless you changed something during install. There are utilities for reading/writing NTFS under Linux, but they're all experimental and I wouldn't mess with it. Personally, I have a FAT32 partition that I use to store common files for use under both Windows and Linux, as they can both safely read/write this format. Isopropyl 18:09, 3 April 2006 (UTC)
And there is no saying that you have to use just 2 partitions. You could split the drive into 3 Partitions. 30 GB for Windows XP install (NTFS), 30 GB for Fedora Core 5, and then a 60 GB FAT32 Partition for your Data. This way you won't have to compromise your Windows Security (not quite an Oxymoron)by using FAT on the OS. Really though if you move install your Programs into the Data Drive you can get by with a 10-15 GB partition for your OS installs. The advantage of this is you don't have to mount the other OS install partition, so you don't mess up something on the other OS install.--Tollwutig 18:47, 3 April 2006 (UTC)
hrmm thx all seems pretty easy. i think the fedora 5 reads ntfs so i dont think file format will be an issue, just wondering how im going to go about splitting this up. i might just install linux to the hard drive i have now, give it 20 GB, and then get a nice 200gb hard drive and put fat32 on it... if anyone stills cares to answer, will there be any difficulties partioning t hsi hard drive seeing its already got about 35 gb of random crap (in ntfs) on it? if not ill just put linux on it tonight modesty 19:32, 3 April 2006 (UTC)
Shouldn't have an issue as long as you can resize the current partition. Norton Partition Magic if you have it is great for this sort of thing, as you cannot change the system partition inside of Windows. If you can find a means to repartition outside of Windows it's fairly straight forward.--Tollwutig 19:48, 3 April 2006 (UTC)
Piggybacking: is this FAT/NTFS thing the reason why on my previous machine I used to be able to modify my Windows 98 drive from within Linux, but on my newer computer with XP the whole of /mnt/windows/ is read only? --Bth 08:42, 4 April 2006 (UTC)
Probably. It's hard to say for sure unless you provide the output of your fstab file. --Optichan 16:53, 4 April 2006 (UTC)

FEASIBILIYY REPORT[edit]

"you have a fun fair in university. Youyou have to stall for anything prepare a feasibility report on it" help me before 10_4_2006

Welcome to Wikipedia. Your question appears to be a homework question. I apologize if this is a misinterpretation, but it is our aim here not to do people's homework for them, but to merely aid them in doing it themselves. Letting someone else do your homework does not help you learn nearly as much as doing it yourself. Please attempt to solve the problem or answer the question yourself first. If you need help with a specific part of your homework, feel free to tell us where you are stuck and ask for help. If you need help grasping the concept of a problem, by all means let us know. —Keenan Pepper 17:17, 3 April 2006 (UTC)
Your question is also poorly written and impolite. Use proper English and say please, if you want our help. StuRat 18:24, 3 April 2006 (UTC)
Probably not an English-speaker primarily, so some slack is granted. What's a "fun fair"? How about making your own wine and setting a vomitorium booth? It would be cheap to do , and very popular. GangofOne 23:19, 3 April 2006 (UTC)
I'm pretty good at recognizing accents, even in writing. This person looks to be a native speaker to me, specifically a native speaker of British English. StuRat 07:44, 4 April 2006 (UTC)
Yep, classic lack of grammatical articles. Superm401 - Talk 23:20, 4 April 2006 (UTC)
THis follow up, Wikipedia:Reference_desk/Science#APOLOGY, says you're wrong, although probably correct about the type of English attempted to be spoken. GangofOne 22:03, 6 April 2006 (UTC)
I'm not sure I believe it, though. Note that the apology is written in fairly good English. This makes me think they were just really sloppy on this post and didn't want to admit it, so made up that story about not speaking English well. StuRat 19:55, 8 April 2006 (UTC)

astronomy/cosmogeny[edit]

If the Cosmic Microwave Background Radiation is due to a single event in the history of the Universe, then why do astronomers continue to record it from every point in the sky? In other words, why has it not rushed by the Earth never to return? —Preceding unsigned comment added by Paul venter (talkcontribs)

Perhaps not suprisingly, you can find your answer at Cosmic_microwave_background_radiation. Chapuisat 19:26, 3 April 2006 (UTC)

Afraid not - if anything, the author of that piece is also confused ....."The photons continued cooling until they reached their present 2.7 K temperature. Accordingly, the radiation from the sky we measure today comes from a spherical surface, called the surface of last scattering, from which the photons that decoupled from interaction with matter in the early universe, 13.7 billion years ago, are just now reaching observers on Earth." What an amazing coincidence! With 13.7 billion years to get here, the timing is such that they turn up just when we start looking, and even more amazingly are centred on Earth, since if Earth were not central to the "spherical surface" mentioned above, the radiation would not be isotropic. So nice try, but no cigar. User Paul venter 3 April 2006

You're using a straw man argument. The article makes perfect sense, just not your misinterpretation of it. —Keenan Pepper 21:21, 3 April 2006 (UTC)
Also, there is no such person as "the author of that piece". Wikipedia is collaboratively authored and edited. See Wikipedia:Introduction. —Keenan Pepper 21:23, 3 April 2006 (UTC)

If I misinterpret the article it is because it lacks logical clarity. On the other hand if you see sense in it, then please enlighten me in detail. As for whether the article has author or authors, it affects the credibility and logic by not a single iota. User:Paul venter 3 April 2006


The universe is constantly expanding. Therefore, there are longer and longer paths for light from the big bang to take before reaching us. There is no need for an "amazing coincidence". —Keenan Pepper 00:05, 4 April 2006 (UTC)

If the 'spherical surface of last scattering' is expanding, the surface remains spherical and does not explain the isotropy or persistence of the CMBR --Paul venter 07:37, 4 April 2006 (UTC)

The "surface of last scattering" is what happens when you look back in time to the early universe from some point inside the current universe. But from the point of view of the history of the universe, there was a particular point in time when the universe cooled down enough to become transparent (because the processes that absorbed and reemitted the photons all the time stopped). When we look back we see the light from the sphere formed by all the points that were at that stage at the right time for the photons they emitted to now be reaching us.
But I rather suspect you're not interested in the real answer. --Bth 09:05, 4 April 2006 (UTC)

There are some difficulties here....firstly, the way I understand the theory is that it was a spherical surface and not a sphere which emitted the light. Secondly, was the emission a burst of light lasting only a very short time, a very long time or is it an ongoing process? If it were only for a short time, then the spherical shape of the emitting surface would mean that when the light does reach any point (except the geometric centre) within that sphere, its behaviour will certainly not be isotropic. And if it were a burst lasting only a short time, then consequently any observer within the sphere would only experience the light later on as a burst of radiation starting at one point in the sky and moving in the shape of a band to a point diametrically opposite - the complete cycle taking anything from seconds to billions of years, depending on where the observer is located inside the sphere.

What a strange thing to think that I am not interested in the real answer..... If you know the real answer, then do share it. --Paul venter 11:13, 4 April 2006 (UTC)

My relpy was an attempt at explaining the real answer. But let's try another way. It is not really helpful to think of it as "a spherical surface emitting the light". The light is the light that was "emitted" when the universe became transparent -- that happened throughout the universe at the same time (in the appropriate coordinate system), about 300,000 years after the Big Bang.
Now the important fact is that as we look out into the universe we are looking "back in time". This is not a special claim of the Big Bang theory, it's a consequence of the finite speed of light. Because it's about two and a half million light years away, we are seeing light from the nearest big galaxy, Andromeda as it was approximately 2.5 million years ago. It should be fairly obvious that there is a spherical shell of radius 2.5 million light years centred on us in which everything we see is at it was 2.5 million years ago, it's just that Andromeda's pretty much the only interesting thing in it. And further out you can have a shell of everything a billion years ago, further out still a shell of everything as it was ten billion years ago. When you get back to 13.4bn years ago, your shell contains the CMB photons because that's the time when the universe became transparent. Beyond that, you can't see because the universe wasn't transparent. That's why it's a spherical shell, it's just a consequence of the fact that we're looking back, the original emission was in all directions -- it's just that all the ones that didn't head off in the right direction for us to see them are out being part of the CMB as seen from elsewhere. The "last scattering" event (ie the universe becoming transparent) happened everywhere simultaneously, pretty much, because it was a consequence of the temperature of the universe, which was still very homogeneous at that point, dropping below the critical temperature needed for any atoms that formed to be instantly reionised -- after that the atoms that formed stuck around (until stars started forming and reionising everything). If you could follow the spot of the universe that we're in now backwards in time, you'd find that it too had been part of that process 13.4bn years ago. To a hypothetical observer 13.4bn light years away photons that were emitted then from our location now are just arriving as their CMB photons.
Is that making any more sense?
(Note that strictly the last scattering shell is not 13.4bn light years in radius as I've implied; when you factor in general relativity and the evolution of the universe it gets more complicated.) --Bth 12:00, 4 April 2006 (UTC)

OK..let's see whether I've got this right. About 13bn years ago (where does this figure come from?) there was a colossal expansion of a very large mass. The expansion was so rapid that after about 300,000 years the outermost edges of the expanding sphere had reached a radius of at least 13bn light-years, since 13bn years after the bang we are still receiving radiation from an event that took place at 300,000 years post big bang. This sphere of matter had at that time cooled sufficiently for internal scattering to end and to become transparent to radiation, resulting in a burst (short-lived?) of radiation which we now observe as the CMBR. This CMBR will have started arriving at Earth from 300,000 yrs post bang, continuously to the present moment, coming from spherical shells progressively further away. At some point in the future one presumes that the CMBR will cease fairly abruptly having come from the outermost shell of the big bang sphere at the moment of transparency - at which point also any radiation having come from outside the big bang sphere will become visible. I am still puzzled as to the mechanism which limits the distance to which we can observe - on the one hand we have the pre-transparency opaque barrier and on the other hand we have Hubble's Law driving matter to a speed faster than that of light. Please let me know whether I have at least the rudiments correct. --Paul venter 22:15, 4 April 2006 (UTC)

In some sort of order:
  • The 13bn years is derived from plugging the observational evidence into the theory. (Judging by some of your edits elsewhere on the 'pedia, you're unconvinced by the idea of a finite-age universe at all. I suggest you have a look at Olbers' paradox for a nice simple proof of that simply from the fact that the sky is dark at night.)
  • According to the now standard version of the theory, the really rapid expansion was at the very earliest stage; see cosmic inflation.
  • There wasn't an "expanding sphere" -- space itself was (and continues to this day) expanding. "Blowing up a balloon" analogies for the Big Ban only really work when you consider them from the point of view of observers embedded in the Flatland-like two dimensional surface of the balloon. The Big Bang was not in any way like a normal "explosion", it's an expansion of everything. (I think this may be the key misconception at play here?)
  • No, the CMBR will not suddenly disappear in the future. We will see the earliest moments of parts of the universe currently inaccessible to us (the universe is bigger than the currently observable universe) -- every CMBR photon that arrives is from a region of the universe that until that moment was previously too far away to see. (But bear in mind that the universe was smaller at the CMB epoch.)
  • The mechanism which limits the distance to which we can observe is the finite age of the universe. There's nothing to see "the other side" of the last scattering surface, everything earlier than that was opaque. An important but subtle distinction: no matter is being "driven to a speed faster than that of light", the universe itself is expanding with that matter embedded in it. (That expansion can be faster than c.)
Any clearer for you? --Bth (not signed in) 5/4/06

A couple of points to note. Olbers' paradox : There could be any number of reasons for light from stars beyond a certain radius not being visible to us - big bang opacity and redshifted light being just two of them. By itself it certainly is not proof of a finite-age universe.

I carefully avoided use of the term 'explosion'

I also think the CMBR will never disappear, but for different reasons. However I'm confused - if the big bang bubble was of finite size at the moment of transparency, then surely at some time in the future, we will observe the CMBR from the last scattering surface. There could be no more CMBR from this particular big bang - or am I missing something?

"There's nothing to see "the other side" of the last scattering surface, everything earlier than that was opaque." I was under the impression that the opacity was a quality of the space inside the big bang bubble before transparency - did this opacity extend outside the bubble as well? Thank you for your patience --Paul venter 07:13, 6 April 2006 (UTC)

Please explain what you mean by "Big Bang bubble". Even though you've avoided using the exact word, between that and your repeated references to "spheres" you sound an awful lot like you're falling victim to the "it's an explosion inside some pre-existing three-dimensional space" fallacy. --Bth 08:42, 6 April 2006 (UTC)

big bang bubble - My phrase, which perhaps I should have defined. Let me do so now. The bubble would include all matter resulting from the big bang/expansion. Radiation from the bubble would obviously define a much larger sphere. And you're quite right - I do think that the big bang was local and within a pre-existing infinite space in which no doubt countless other big bangs have taken place, are currently taking place, and will within the infinite future take place. Is there any good evidence to indicate that this is not the case? --Paul venter 11:56, 6 April 2006 (UTC)

Intermolecular Bonds[edit]

I can't figure out why, when I tear paper, the bonds holding the paper together on an intermolecular level break but when I put the two sheets next to one another and add pressure they don't form agian. It seems like a rather stupid question but I can't think of an explaination on a chemical (molecular) level. Thanks. -Haon 18:29, 3 April 2006 (UTC)

Poor example as you aren't really breaking chemical bonds but physical bonds of interwoven fibers. You're just pulling the cellulose fibers apart. In order to get the paper to come back together you would have to reweave the Cellulose fibers back together. Chemically speaking, breaking bonds releases energy. Creating chemical bonds requires energy.

A good example of this is Sugar. Plants make sugar out of carbon dioxide and water using the Energy of absorbed light. (Photosynthesis) At same time all life (even plants) take the Sugar and use Oxygen to break it down into Carbon Dioxide and Water releasing the energy which was stored in it by photosynthesis. This process is called Cellular Respiration.--Tollwutig 18:39, 3 April 2006 (UTC)

Chemically speaking, breaking bonds releases energy. Creating chemical bonds requires energy. This is wrong. If breaking bonds released energy, they would break spontaneously and molecules would not be stable.
Plants use the energy they get from sunlight to break the strong bonds of H2O and CO2 and form sugars with weaker bonds. Animals break the weak bonds of the sugars and form the strong bonds of H2O and CO2 which releases energy.
The stuff about interwoven fibers was the right answer. —Keenan Pepper 21:17, 3 April 2006 (UTC)
Some chemical reactions are exothermic (releasing energy) and others are endothermic (using energy). Those reactions that release energy, like say the detonation of dynamite, are rather unstable, but still require specific conditions for the reaction to take place. Typically, this is some combination of heat and/or pressure. StuRat 07:37, 4 April 2006 (UTC)
"when I tear paper, the bonds holding the paper together on an intermolecular level break but when I put the two sheets next to one another and add pressure they don't form agian". If you alligned the atoms EXACTLY the way they were, the bonds WOULD form again. The problem is , when you rip paper the ripped edge has about, oh, maybe about 10^22 bonds , give or take, that you have disturbed, and the atoms exposed are vibrating (at room temperature) and maybe combine with the air, and the fibers got jumbled and distorted, so when you put them together, they no longer match up. If you take the time to match up all 10^22 joints, then the joint will be seemless. Let us know when you're done. GangofOne 23:10, 3 April 2006 (UTC)
Actually, this sort of thing can happen. It blew my mind when I first learned of cold welding. Chemical bonding, in addition to geometric considerations, is also a component of friction. As a poster above said, there is mechanical bonding involved in holding paper fibers together, but under the right conditions (particularly high-temperature polished surfaces in a vacuum) you can get all sorts of fun things to happen like sintering. —Ben FrantzDale 02:44, 6 April 2006 (UTC)

SARS relationship to Avian Flu, H5N1[edit]

I have spent considerable time studying the situation regarding the potential pandemic due to the currently circulating H5N1 A virus. SARS was also a virus, though of a different kind, and that pandemic was tightly contained. According to WHO about 8000 people fell ill with SARS and about 800 of them died. That is a miniscule set of numbers compared to even the most optomistic estimates of what might happen in the human population should H5N1 change to become easily transmitted among people. Why is there such a huge quantitative difference? How is it that we managed to survive SARS so well and seem to be so vulnerable to H5N1?

I have been to both the WHO and CDC sites as well as Wikipedia seeking some insights but I can find nothing. Everyone treats each illness quite independently of the other.

I'd appreciate any help you can bring to bear on this question. - unsigned

H5N1 is pretty much a standard influenza virus and follows the same pattern as other. As for its ability to spread if it mutates to be contagious between humans, it'll spread like any other influenza. While I do not know the specific information on SARS pathogenicity, it is not as easily transmitted as influenza, which is only surpassed in contagiousness by the Common Cold. Influenza is contagious 12-18 hours before symptoms are ever apparent.(not sure about SARS). This means that someone who gets Influenza in Tokyo could get on a plane, spread the virus to all other passengers and arrive in L.A. with only a slight sniffle. In the meantime now you have several hundred people who are potentially infected, and not showing symptoms.
As a side note the mortality rate of H5N1 is over exaggerated as the reports of 80% mortality are obscured by the fact that only the most severe cases have been reported. How often is H5N1 deadly in cases where the symptoms do not warranty treatment at a medical facility, and thus go unreported?--Tollwutig 19:44, 3 April 2006 (UTC)
SARS has low inherent transmissibility. Flu has high inherent transmissibility. It's the difference between a fire on a dry grass plain and a fire on a wet grass plain. Extensive studies looking for mild missed H5N1 cases in Cambodia found NONE. Avian adapted H5N1 kills half the humans that get it, but has near zero human to human transmissibility. If and when a human adapted strain of H5N1 evolves, no one knows what its transmissibility nor what its mortality rates will be. We have no data to guess with because this strain is acting different (more deadly, more virulant, more transmissible) than all other known strains of flu - ever. The world's best experts say they are very scared and have stocked up months worth of food and water and medicine. Dr. David Nabarro, chief avian flu coordinator for the United Nations, describes himself as "quite scared"; says avian flu has too many unanswered questions; and if the disease starts spreading to humans, borders will close, airports will shut down, and travelers everywhere will be stranded. If the worst happens, the best way to survive is to lock your doors, stay inside,and have no contact with anyone outside your home for as long as your food and water last. In the 1918 pandemic some entire villeges were wiped out while some entire cities blocked all incoming traffic of any kind and had no deaths. WAS 4.250 21:11, 6 April 2006 (UTC)

Humming and Software[edit]

Does anyone know of any software where you hum/whistle/la/etc. into a microphone and it gives you an approximate pitch (or note)? Even better would be one where it measures the duration of the note as well and records it. The reason I ask is because I find it easy (as I am sure many other people do) to invent and hum a tune, but when it comes to playing it on an instrument or writing it down, I have no clue what to do (even though I can play music reasonably well). Alternatively, can anyone give me some pointers on how I would write a basic program that could do this? Any suggestions would be greatly appreciated. 80.229.152.246 20:27, 3 April 2006 (UTC)

While I do not know of a specific program that does what you want in one complete package with a pretty pink bow on top, it isn't really complicated to record the microphone into a wav file and then convert the wav to midi. Once in midi, the notes will quanitized to specific pitches and durations. Also, there are many composition programs that allow you to view midi files as sheet music or rolling bar graphs so you can adjust it further. --Kainaw (talk) 22:01, 3 April 2006 (UTC)
Used to be such a thing for sale. See also Vocoder, Fourier transform GangofOne 22:55, 3 April 2006 (UTC)
"...and then convert the wav to midi." — That's equivalent to the original problem. —Keenan Pepper 23:52, 3 April 2006 (UTC)
Apple's GarageBand (a part of Apple's $79 iLife suite) has an instrument tuner that shows what note is being played, and that includes through a plain ol' microphone. I had some fun humming "Do Re Mi" and seeing how close I was to actually humming the correct notes. Of course, GarageBand is Mac-only, so I doubt that'd help. :P —OneofThem(talk)(contribs) 00:28, 4 April 2006 (UTC)
just record it regularly, and then match each note to a note on the keyboard or a guitar. the main problem is that youre probably not singing in tune, but tuned to some weird quarter note or half pitch to begin with. try playing a note on the guitar or keyboard, then matching that note, and then hum from there while recording it. then you can play it back and learn it. if you do this enough your ears will get real good at figuring out which note is which. or you could try what everyone else has suggested... if the point is to get good at playing at the instrument youre probably cheating yourself if you use a program to do the work for you modesty 01:56, 4 April 2006 (UTC)
On a side note, a clean whistling sound is very similiar to a pure sine wave, which is really trivial to find a matching frequency with by using some mathematical tricks. I wonder if somone coded a program for this already, shouldn't be hard. (I did some nasty thing like this on mIRC, and while it did work, it didn't work all that nicely) ☢ Ҡiff 06:06, 4 April 2006 (UTC)
Software of the type the questioner is asking for must exist, because what he's describing is also the basic mode of operation of the Singstar games. --Bth 09:38, 4 April 2006 (UTC)
Thanks everyone for your answers. The point was not to get good at playing the instrument but to see if a computer program has already been written. I'll probably have a go myself and put it on Sourceforge if it is any good. P.S. Thanks for the sine wave tip.

80.229.152.246 18:12, 4 April 2006 (UTC)

I was facing the exact same issue when I had to write a song for a project in college. I ended up using the Transcribe!, software, which is a very compact, but extremely easy to use program. You can hum the tune into your mic, which the program will record, and then show the waveform graph. You can then select sections (e.g. single notes that you hummed) within the graph, and the program shows you nice distribution graph of the pitches it detected in that section over a piano layout (see the screnshots section, and you'll understand). I then played the notes on my MIDI keyboard to determine which were the ones I intended to hum, and wrote the notes down. It's probably not the best program out there and isn't as robust as many others, but it was so simple to use, that I ended up sticking with it. Hope this helps. --Aramգուտանգ 05:49, 5 April 2006 (UTC)

Question about the VLA[edit]

In the article Very Large Array there is aline which reads:

There are four commonly used configurations, designated A (the largest) through D (the tightest, when all the dishes are within 600 m of the center point).

What is this difference between these configurations, by which I mean what do they allow observers to see? are the images clearer in one configuration than another, or is this done simply to change perspective of an observed object?

Briefly, wider array configurations give a narrower field of view and higher resolution. (This is one reason for the creation of the VLBA – the Very Long Baseline Array – which links a network of radio telescomes spanning 8,000 km). Moving the dishes closer together widens the field of view so that larger objects can be observed. Different configurations of the dishes represent different compromises between field of view, resolution, and apparent brightness of radio sources.
Here's a schedule for the different configurations over the next few years. (The VLA is operated under each configuration for approximately 4 months at a time.) Finally, here's a technical publication detailing the resolution limits of the VLA in each configuration at a range of wavelengths. TenOfAllTrades(talk) 02:03, 4 April 2006 (UTC)
  • Thanks. I apreciate it.

Chemical Reaction[edit]

I am making a battery out of a lemon for school. For the project, I am using a "juicy" lemon to create electricity. I am putting a strip of copper and a strip of zinc in the lemon so the zinc and copper don't touch. I want to know how the the juice from the lemon, copper, and zinc creates a chemical reaction to produce electricity. Please explain how the chemical reaction works and how it generates electricity, but please keep it relatively simple if it's possible (I'm only in 6th grade). Thanks! Anna

April 4[edit]

Neutrinos[edit]

It has come to my attention that we are under constant attack by neutrinos. I was shocked to learn that there has been no study of the health effects of these unwelcome particles. Has there been no attempt to build a neutrino shield? I believe it is a liberal conspiracy.

Neutrinos are naturally produced and have been bombarding Earth since it was created (at least, that's what I'm assuming by reading the article on neutrinos). I seriously doubt that they're harmful, nor that there's a "liberal conspiracy" involved. (lol) —OneofThem(talk)(contribs) 00:40, 4 April 2006 (UTC)

A neutrino shield would have to be several million miles thick. With all that material, I'd rather build a dyson sphere. Night Gyr 01:01, 4 April 2006 (UTC)

The neutrino article says you'd need something like a half light year of lead to make an impact on neutrino bombardment. Is this a serious question? If this is a conspiracy, daylight savings time is the government's way of stealing time from you. Isopropyl 01:13, 4 April 2006 (UTC)

If neutrinos are harmful to living things, you will never know. This is because it is impossible to have a control (case) to test the effects of not being bombarded with neutrinos. Ohanian 01:32, 4 April 2006 (UTC)

Given that all terrestial life has been under neutrino bombardment since since the Earth was created, removing those neutrino could theoretically be harmful. We know too little about them to say otherwise, and have no experimental or anecdotal evidence of whether life could even exist without their presence. Consider a somewhat extreme analogy - no-one knew much about oxygen prior to the 18th century - thankfully no-one decided to shield life from it. Or, to put it simply: it ain't broke - don't try to fix it. Grutness...wha? 01:49, 4 April 2006 (UTC)

What I read was that the neutrino cross section of a human being per time is about 1 neutrino/70 years or so. When you actally interact with one, you die. How else can you explain this amazing coincedence? GangofOne 07:18, 4 April 2006 (UTC)
Your ideas intrigue me, and I wish to subscribe to your newsletter. Tzarius 08:40, 4 April 2006 (UTC)

I would say they are both harmful and helpful. They are one of many factors which may cause genetic mutations. Most mutations have little effect, and at most kill the cell. However, some are harmful, such as causing cancer, and quite rarely they are actually helpful, if the mutation is in a reproductive cell and is beneficial. Thus, they may actually help to drive evolution. StuRat 07:24, 4 April 2006 (UTC)

Neutrinos do not cause genetic mutations. --BluePlatypus 12:01, 4 April 2006 (UTC)
While the vast majority pass right through the human body (and even the planet) without reacting, a rare few do cause a reaction. That is how we can detect them. If this reaction happens to occur by a strand of DNA, a mutation can occur. StuRat 20:00, 8 April 2006 (UTC)

Bots[edit]

I'd like to do some experimenting with internet bots (e.g. Wikipedia editing bot, Bluebot). What programming language does this require? Does anyone know good links for downloading a compiler or for a good tutorial? Thanks. -Snpoj 01:29, 4 April 2006 (UTC)

AFAIK, many Wikipedia bots use Python. Different types of bots may be programmed using different languages. For example, I've programmed a responding IRC bot in Perl because of its efficiency in string handling. –Mysid 06:18, 4 April 2006 (UTC)

Has this already happened[edit]

The folly of basing Scientific Research on unobservables events. Ernst Mach did not believe in the theory of the atom, saying that "atom" is just a word and nothing more.
Mach went on. If you do believe in the atom, what would happen? Well physics will generate many many results. Physicists will construct models of the atom and then they will find out that these model do not work.
So then physicists will replace the models with newer mathematical models because mathematical terms can be stretch to fit any data. And then physicists will end up saying that "because we can't observe it, we can't measure it. So the position might be this and the energy is probably that."
Then the physicists will be driven to the theory that the energy comes and goes more or less at random. All sorts of trash will appear in their theory. There will be "elementary particles" with strange names and anti-matter which ought to be there but isn't. These "particles" would either behaving like a wave or discrete particles depending on the observable outcome. So the laws of physics will degenerate into mumbo jumbo.

My god! Imagine living in a world where this has already happened. What an utterly weird world it must be. Ohanian 01:40, 4 April 2006 (UTC)

I don't know what your point is, but that quote is a fake. Melchoir 01:50, 4 April 2006 (UTC)
Holy crap! They've figured out that we're making it all up! Run! -- An evil particle physicist 01:51, 4 April 2006 (UTC)


Particle physics ain't simple and the mathematics correlates with experimentation. There's nothing wrong with revising "models" and making analogies to help us understand physical concepts on a microscopic level. imo, our inability to interpret obscure mathematics (the one "true", non-analogous model) is why quantum mechanics must appear to our mind as "mumbo jumbo". Trust the math even if we're destined not to fully comprehend it.
As for the subject's question, do you mean stuff like Polywater and other forms of so-called Pathological science?
-Snpoj 01:54, 4 April 2006 (UTC)

I believe the true test of any model, such as the model of the atom, is whether it can predict things which aren't already known. I believe the models of the atom have predicted most, but not all, atomic interactions. If we look at a simpler model, a globe is a model of the Earth. While not specifically designed to measure the distance from Bombay to London, it could be used for this purpose by laying a string on the globe between the two, then scaling up the string's length to account for the scale of the globe. However, in other respects, like the density, the globe may not be correct. Thus, it is a good, but not perfect, model. I think atomic theory falls into the same category. The earliest versions, with electrons in planar, circular orbits, is the least accurate, and the current, far more complex model with electrons inhabiting waveform probability functions, is the most accurate model. StuRat 07:15, 4 April 2006 (UTC)

Read Feynman's books. – b_jonas 13:54, 4 April 2006 (UTC)
And there is no such thing as a "perfect model" -- a model must, by definition, be something lesser than the ultimate truth. And for good reason, too! Not much one can do with a 1:1 map. --Fastfission 01:14, 5 April 2006 (UTC)
One must here realize the difference between ideas and reality. Physicists, in modelling our world with theories and mathematics etc., have never really claimed that their work is how nature really is behind the scenes. Models, as they are so named, are only made to help our understanding and use of the world and materials around us, but never as a direct replacement for what actually is there. In the ancient world, for instance, unlike what was later related, many educated individuals never believed the heliocentric model to be what the world was "really" like, but they accept it anyway simply because it is often the easiest way then conceivable to interpret the observations around us. Thus it is the same with your query- models are essentially idealistic, yet no idea can truely capture reality in the sense of that- which- is. In a way physicists are creating the laws of nature- we have no idea, and can never know, whether atoms really existed "behind the scenes". But the best way to understand physical models are to think of them as the- very limited!- human versions of nature's workings as we see it. They never are, and were never meant to be, replacements of what actually is present. Sometimes we are so involved in our symbol means that we believe the symbols to be reality itself, when in fact it is only a weak manifest. Luthinya 20:07, 10 April 2006 (UTC)

multi-language support website problem[edit]

Hai,

i am programmer in php . i am creating a website with multi-language support. i.e english,tamil,sinhalese support website. and my problem is how to show the site content in different languages.(because browser doesnot support the languages how to install fonts dynamically or how to use unicode support for my website). please any one provide a solution.waiting for your reply

Thanking you, sudhakar.

Create your website in UTF-8 and use Content negotiation to select the language automatically. Installing fonts is not your problem, it is the problem of the website user. —Masatran 03:17, 4 April 2006 (UTC)
I think he wants to make it his problem, so the user won't have to deal with it, but can still see the page correctly. - Taxman Talk 23:33, 4 April 2006 (UTC)
I think it would be safe to assume that the user would have the appropriate fonts for their language/script already installed on their computer. I don't think there would really be much point them using that computer otherwise. --alien2k 22:38, 11 April 2006 (UTC)

Does light have mass?[edit]

Does light have mass? I have only found conflicting or incomplete answers on the internet. Thanks

--Jared

Photons (the particles that carry EM forces) have no mass, but can impart momentum -- see Compton scattering Raul654 03:46, 4 April 2006 (UTC)
Nice explanation from the physics FAQ. EricR 04:59, 4 April 2006 (UTC)

Another planet?[edit]

If there were a planet similar to Earth in both size and solar distance, always orbiting on the opposite side of the sun, how would we be able to know it was there?

Hmm... even if the Earth 2 were on an exactly opposite orbit from Earth at some point in time, perturbations from the other planets would affect the twins unequally, and that should eventually mess up the alignment enough to make Earth 2 directly visible from Earth. You could do a numerical simulation to figure out how long that would take; I'm not sure how to estimate it. Melchoir 04:37, 4 April 2006 (UTC)
See Counter-Earth for more information. — Knowledge Seeker 04:48, 4 April 2006 (UTC)
The orbit of earth around the sun is an ellipse. See Kepler's laws of planetary motion for why Earth 2 could never be always on the opposite side of the sun. EricR 04:56, 4 April 2006 (UTC)
Then the other planet would have to be an ellipse. Without a symmetry-breaking influence (such as the other planets), there is nothing preventing another planet from occupying an exacly opposite orbit. Melchoir 05:26, 4 April 2006 (UTC)
You're right of course. Looks like i also egagerated the eccentricity. EricR 05:50, 4 April 2006 (UTC)
I think you were right to start with Eric, but I've posted my analysis as another question at the bottom of the page. DJ Clayworth 20:32, 6 April 2006 (UTC)
My dad once theorized that there might be an identical Sun on the opposite side of the Milky Way with an identical Earth orbiting it that supports (and has) life on it, and that the only reason that neither Earth has detected the other is because we can't see through the center of the galaxy very well. :P —OneofThem(talk)(contribs) 17:29, 4 April 2006 (UTC)
Recent work in viewing distant galaxies has used a gravitational magnifying glass sort of trick caused by the gravitational bend of clusters of nearer galaxies. Why wouldn't the clusters of stars in the center of the galaxy provide the same effect for seeing clearer images of the opposite side of the galaxy. But, to the point of this question, the opposite side of the Sun has been examined repeatedly by our satellites. I have no idea how many we've slung out into space, but many of them have seen around the Sun while looking at other planets, moons, asteroids, etc... --Kainaw (talk) 13:51, 5 April 2006 (UTC)

Tatto Help[edit]

Dear Readers, I'm in the middle of getting a tattoo but i cant find the formula for this saying. It goes,"Once you are Born, You begin to Die." Its not the actuall saying but thats what it means. There is a formula for this, the Theory starts with an "E". Please Help Thank You, Bare Skin

Are you thinking of entropy? TenOfAllTrades(talk) 05:59, 4 April 2006 (UTC)
And the best phrasing for that is Dylan's: "He not busy being born is busy dying." --jpgordon∇∆∇∆ 15:34, 5 April 2006 (UTC)
  • Maybe you're thinking of Manlius? Once born we begin to die, the end depends on the beginning. Or any of the similar statements here: [6]. Personally, I vote for the entropy game rules: You can't win, you can't break even, you can not leave the game. Ande B 05:20, 6 April 2006 (UTC)

Cause of death[edit]

I am researching my family history and have a relative aged 19 months who died from " Tabes mesenterita" according to her detah certificat. Could anybody please advise what this is? Tired wikipedia amd medical networks but could only find that "tabes" means gegeneration - i think!

May thx

Andy

A mailing list archive from 7 years ago contains a similar question. Maybe the words could have been Tabs Mesenterica, which means tuberculosis of the lymph glands inside the abdomen – a children's illness. (source) –Mysid 07:11, 4 April 2006 (UTC)

Your term is spelled correctly but is difficult to match to a specific modern diagnosis. Tabes is an old medical term that means wasting. It is a nonspecific term, and could have resulted from many different diseases. Mesenterica is the adjectival form of the word mesentery, which in modern medical usage refers to the tissue that connects the intestines to the rest of the abdominal cavity and contains lymph nodes and blood vessels. The interpretation might vary by the date and place of the death certificate: the term tabes was used more widely in French than English medical writing and survived in more contexts in the 20th century. In English, the term tabes disappeared from medical usage in the 20th century except as part of the term tabes dorsalis, which is a degeneration of spinal nerves caused by syphilis, not likely the cause of an infant's death.

I also suspect mesenteric may have also been used before the late 19th century in a wider sense to mean "intestinal" but I am not certain of this.

If the death certificate was in English and before the late 19th century, the diagnosis was probably not based on an autopsy or diagnostic tests, and so represents a description of the disease process. Describing wasting as a cause of an infant's death mainly implies that the cause of death was not physical trauma, acute infection or illness, or sudden cessation of breathing but a more prolonged process in which failure to thrive was the chief manifestation. If I am correct that a practicing physician might use the term mesenteric more broadly to imply "involving the intestines or abdomen", then it suggests that diarrhea or abdominal distention were the most prominent signs of the illness. There are many causes of failure to thrive with gastrointestinal manifestations that could have led to death before the 20th century: cystic fibrosis, or chronic infection such as tuberculosis. The other type of abdominal disease that could have caused a wasting death would have been an obstruction of the stomach or intestines (e.g., pyloric stenosis, duodenal atresia). I do not know whether tubercular mesenteric adenitis could cause enough enlargement to be palpable in the abdomen and identifiable by a doctor as a cause of death without an autopsy. Can you give us some more context (date and location of death)? alteripse 11:30, 4 April 2006 (UTC)

How to change the magnetic strength of the magnet bar ?[edit]

I have one magnet bar and one ion bar , one man talk me that he can make the magnetic field of this magnet,it shall be stronger or weeker by placing one ion bar with the adjustable thickness . Do you aggree this?

Location of the first observed point : Z, Location of the magnet bar  : M, Location of the ion bar  : I, Location of the 2nd observed point  : Y


Z-------------MI-------------Y

Case (1): thickness of the ion bar is 5mm; Case (2):thickness of the ion bar is 1mm

In the case (1), we use one ion bar which is applied to the magnet bar with the thickness of about 5mm . In the case (2), we use one ion bar which is applied to the magnet bar with the thickness of about 1mm .

       At the point of Z, (in the both cases) the magnetic field is the same strength. 

And at the point Y in the case (1), by causing of the reluctance effect , and the thickness of the ion bar is thicker , the magnetic field shall be weeker than the point Y of the case (2) . A man talk me that he can make the magnetic field of this magnet,it shall be stronger or weeker by placing one ion bar with the adjustable thickness . I.e. that he want to talk at the point of Z: At Z in the case (1), the field is smaller than Z in the case (2). Is it right? Wiki

Your diagram doesn't seem to display for me, because it's on your computer. You need to upload it to Wikipedia so we can see it. Try using the "Upload file" link on the left to do this.
Changing the material and material quantity can have an effect. Some materials, like iron, conduct magnetic fields better than others, like air. Resistance to a magnetic field is called reluctance. StuRat 08:43, 4 April 2006 (UTC)

Kids, if you find an ion bar on the street, do not touch it!!! They can be very reactive, and are used to propel starships. --Zeizmic 15:18, 4 April 2006 (UTC)

Using the same disk space for swap space and pagefile on a dual boot computer[edit]

My situation is as follows. I have a dual boot computer with Windows XP and Ubuntu 5.10. I have told Windows to put its pagefile in a dedicated partition located at the beginning of the hard drive (I have just one). My question is: can I tell Linux to use that pagefile as a swap file in an effective way? Just telling it the standard way (swapon etc.) does not work well because apparently it tries to mount the swap space before that partition, and so it cannot see it. When it mounts that partition later, it does not know that it has to swapon that file again. So the result is no mounted swap space. I was also told (Google groups) that I could format that partition to a swap partition every time Linux starts and format it back to FAT32 every times it shuts down (and re-create the swap file), but I do not know how to do this. Can anyone give me advice, please? Any suggestion about using the same physical space for swap/virtual memory is very welcome. Cthulhu.mythos 10:16, 4 April 2006 (UTC)

It's possible, but it's not easy to do.
You can use the same file in both linux and windows as a swap file, but the problem is that both linux and windows require that the file is prepared in a special way before it can be used as a swap file (this is in contrary to BSD, which I think doesn't require this). For linux, this is easy to do, because you can use the mkswap utility every bootup before you turn the swap on. For windows, it's more difficult, because there's no simple way this preparation can be done. I've read about this problem a few years ago, and it said that a kludge that works is to save the first few blocks of the file after windows have prepared it, and resore that every time linux is shut down (I've never tried this myself). However, that was ages ago, for an older version of windows, and at the time when hard disk capacity was more expensive. These days, it's probably not a problem to allocate separate swap space for each OS you install. (Still, if you insist, I wouldn't recommend making a FAT partition every time linux shuts down, I'd rather use a swap file instead of a partition.)
Yeah, I've found the document talking about this: Linux Swap Space Mini-HOWTO. – b_jonas 13:36, 4 April 2006 (UTC)
Thanks. It does semm quite difficult, actually. But maybe I will try to do it for the sake of it. Cthulhu.mythos 12:17, 5 April 2006 (UTC)
If you want to do it for the geek/hobbey value, knock yourself out, but otherwise, I'd say it's not worth it. hard drive space is cheap. For great justice. 00:01, 6 April 2006 (UTC)
One more note. Do not set a too large swap space, as that wastes the main memory. Twice the size of the memory is enough. – b_jonas 19:55, 7 April 2006 (UTC)

Heliocentric[edit]

The word Heliocentric is taken from astronomy (sun centered model. What would be the term in social meanings - when a system is centered around a person?

A particular person, or people in general? "Anthropocentric" for the latter, not too sure for the former, it would probably depend on what makes that person so special that they have a system built around them. You might get more useful replies over at the Language refdesk, to be honest. --Bth 10:56, 4 April 2006 (UTC)
Egocentric. --Hughcharlesparker 09:30, 5 April 2006 (UTC)

Thanks :-)

Mental illness: Medicine[edit]

I want detailed reading that would throw light on what factors could show that a person did or did not have a mental illness in the past, if there is no evidence of it in the present

Please reply, My email is (address removed to prevent e-mail spam)

THANKS!!!

It's difficult enough if you are a mental health professional with access to the patient. Any speculation like this, while possibly fun, is simply speculation. For great justice. 23:59, 5 April 2006 (UTC)
You need to do a search for "forensic psychiatry." To get decent texts, you should try a college library, preferably one with an affiliated medical school. Public libraries are often able to do inter-library loans for works kept in nearly any library imaginable, including foreign libraries. Ande B 05:28, 6 April 2006 (UTC)

Old names for illnesses[edit]

I was looking at the vital statistics in an old almanac a few months ago and discovered a list of the number of people who died from different diseases and ailments - among which were "Cats in the belly" and "Planet". I've hunted both online and offline and cannot find any clue as to what Planet might be, though I found some mention of cats in the belly related to problems with childbirth. Can anyone throw any light on what these ailments might be? Grutness...wha? 13:51, 4 April 2006 (UTC)

I can help with the second one - "planet" listed as a cause of death was saying that the death of the person was caused by a planet being in the wrong place, and causing so much misfortune that the person simply keeled over. Astrology taken to an extreme, if you will. Looking at it from a modern perspective, it was an explanation given by doctors for deaths which didn't have an obvious cause, at least not to the medicine of their time. Possible 'real' causes might have included things like strokes, heart failure and other sudden-death conditions which give little warning. — QuantumEleven | (talk) 17:11, 4 April 2006 (UTC)

an interesting question...[edit]

hey guys......can someone explain me why some types of substances are insoluble(in pure water) but soluble in acid or in base?? just like zinc, calcium carbonate,zinc oxide.

It is because the substance is insoluble in water, but reacts with acid or base to create a soluble product. For example, calcium carbonate (which is insoluble) reacts with hydrochloric acid to form calcium chloride, which is soluble: CaCO3(s) + 2HCl(aq) → CaCl2(aq) + CO2(g) + H2O(l) -- AJR | Talk 16:50, 4 April 2006 (UTC)
Can you do my homework for me too, AJR? —This unsigned comment was added by 12.41.204.3 (talkcontribs) 19:47, 4 April 2006 UTC.
No, but I believe that there are site that will, but they charge a fee. Jon513 17:11, 10 April 2006 (UTC)

John MacAdam[edit]

John MacAdam invented the hardtop roads, but I would like to know when and how. Your page on John MacAdams is small and says nothing (besides the tiny nibble I added) about hardtop roads.

someone anser me...plzzzzzzzzz

Did you check the related article on macadam? — Lomn Talk 15:34, 4 April 2006 (UTC)

Research Goya theory?[edit]

I am trying to find information on a theory proposed several years ago by persons unknown ( I can't remember a name.) to the best of my knowledge he was located somewhere in England and as best as I can remember the title of the theory was THE GOYA THEORY. The rudiments of which were that a natural balance exists in nature to wit: that every element attempts to attain a state of equilibrium so that for example hot and cold will gravitate toward a medium temperature.That is simplistic I realize but the best example I could come up with on short notice.

Any and all help appreciated. Yours truly,Jim Pfaff
See Gaia hypothesis. Frencheigh 15:41, 4 April 2006 (UTC)

Thanks much,Jim

Dogs Watching Television[edit]

My grandmother used to have a West Highland White Terrier that was able to notice other animals on the television and respond with growls and barks etc. But my attempts to get our Alsation-Collie cross to notice other animals on the television have all failed. He just wont look at the TV. Why wont my dog watch the tele? --Username132 (talk) 15:20, 4 April 2006 (UTC)

Dogs mental capacity differs from animal to animal. Same with other animals. I used to have a dog that did not like the mirror I had leaned up against the wall. She would go clear up over the bed to avoid walking next to it. When I blocked the bed route, she went past it at a trot with her head down and would not look at it.
Right, one of the dogs is smarter than the other one. You work out which is which. --Trovatore 21:35, 4 April 2006 (UTC)

The family used to have a cat that would look behind the mirrror to try to find that other cat that looked like her. We used to have a creepy cat statue with eyes that seemed to follow you, the housecat would raise his hackles the first time he saw that. When you say the dog won't look at the TV, do you mean the dog actively avoids the set, or just shows no interest? I suggest running a tape of a barkign dog on TV, and see what that does.

I can think of two reasons why a dog wouldn't see a TV image as the real thing. One is that they may have a different persistence of vision than humans. That is, they may see the TV image as a series of still images, not as motion, as we do. The other is that dogs rely less on vision, and more on other senses, particularly smell, than humans. So, if the TV doesn't smell like another animal, they don't believe it. With humans "seeing is believing", whereas, with dogs, "smelling is believing". StuRat 02:22, 5 April 2006 (UTC)
I've grown up around dogs my entire life, and I've always been curious at their reaction to the television. Eventually I learned that animals simply have a greatly different perception of the world from humans. We, for example, live in a world of symbols: we have an intuitive understanding of symbolic representation, such as letters for words and words for actions and things. This symbolic understanding extends to 2-dimensional pictures as 3-dimensional objects: while we take for granted that the illuminated flashing box is showing us representations of real objects (like animals), it is unlikely that most dogs can make that logical leap (they don't drool at dog food commercials, for example). It is far more likely that the terrier was responing to the sounds of the televised animals, and did what dogs do: he barked back. – ClockworkSoul 03:34, 5 April 2006 (UTC)
You could perform a small test on your dog. Find a copy of the album Animals by Pink Floyd. There's a track on it called, simply, "Dogs". In the background it has sound effects of dogs barking. Over the years I've had a few dogs and some of them reacted to the barking while the rest don't acknowledge it at all. This would at least give you an idea as to whether it's the television he's avoiding or if he's just not interested. Dismas|(talk) 10:01, 5 April 2006 (UTC)
  • Here's the status in our household: Stella, a big fluff of a chow/German shepherd/Aussie mix, watches stuff on TV. The most fun was a few years ago when a squirrel ran out onto the field at Pac Bell Park during a Giants game; Stella started acting exactly as she does when she spots a squirrel in the great outdoors. However, she utterly ignored it when we replayed it for her on the Tivo. Mr. Slick, a great big lummox of a boycat who has always lived indoors, is fascinated especially when we put on videos of birds and critters, and even when the TV is off or on the news, will sometimes go and try to find the birdies behind the TV. (We had to stop leaving the bird video on because we worried he would scratch through the screen of the LCD TV.) The other two cats, however, spent a fair amount of their youth as outside cats, and are not in the least bit impressed or even interested in the TV birds. So, yeah, it varies dramatically from critter to critter. --jpgordon∇∆∇∆ 15:29, 5 April 2006 (UTC)

Also, it depends where they grew up. For instance, I had a stray(cat) who would always run from the t.v. Then, her kittens which we had from birth are fine with it.

Pyrite and Sulphur[edit]

Please can you tell me what type of rock (sedimentary rock, igneous rock or metamorphic rock) sulphur and pyrite are? Computerjoe's talk 19:20, 4 April 2006 (UTC)

Actually, they are both considered minerals, not rocks. --Ed (Edgar181) 19:28, 4 April 2006 (UTC)
Very well, but would it still be possible to class them under one of the above three? Computerjoe's talk 20:18, 4 April 2006 (UTC)
I don't think so, because rocks and minerals really have distinct definitions. Minerals have a homogeneous composition and rocks are defined as aggregates of different minerals. A mineral might be a component of different rocks that fall into each of the three classes. --Ed (Edgar181) 20:40, 4 April 2006 (UTC)
Thank you Ed! :D Computerjoe's talk 21:16, 4 April 2006 (UTC)

weather[edit]

what device points the way the wind is blowing —The preceding unsigned comment was added by 24.182.128.238 (talkcontribs) 19:43, 4 April 2006 (UTC)

Perhaps a weather vane? Isopropyl 19:48, 4 April 2006 (UTC)

You don't need a weatherman for this. Just keep a clean nose, be careful of the plainclothes. --Trovatore 19:49, 4 April 2006 (UTC)

Any way the wind blows, doesn't really matter to me. Isopropyl 23:24, 4 April 2006 (UTC)

Politicians use straw polls to determine which way the wind is blowing, which is occasionally affected when one of the gasbags releases more hot air than usual. StuRat 08:56, 5 April 2006 (UTC)

What's the deal with Firefox freezing on Macs?[edit]

In my office I use a mac, and I find that Firefox often freezes if it encounters something it doesn't know how to handle. For instance, if I were to try to go to text twist, a page with, I think, shockwave, Firefox will freeze completely and I have to force-quit out of it. This happens on maybe 20% of pages with odd media formats within them, so at least once a day. I'm using a brand new iMac with a pentium chip, barely used, and the latest version of Firefox. The exact same thing happens on the two-year-old iMac in the office, so I don't think it's just my computer.

When Firefox in Windows reaches something it can't handle, it tells me so or just refuses to load that page. Here on the Mac I have to force-quit, losing all my tabs and anything I've been working on in Firefox. How can I get it to be a bit more graceful in dealing with unexpected formats? — Asbestos | Talk (RFC) 20:03, 4 April 2006 (UTC)

Actually, I suffer quite a bit with Windows. If you get a chance, use talkback. This enables developers to search BugZilla much quicker. Also, you could search BugZilla. Computerjoe's talk 20:17, 4 April 2006 (UTC)
Are you using the latest versions of OS X and of Firefox? It is rock solid on my machine. Why are you using Firefox? Is there some specific function you need, or might Camano or Safari meet your needs? For great justice. 23:52, 5 April 2006 (UTC)
Ahh, but it's Java, not Shockwave, which is probably the reason why you're freezing. In general, the Java VM likes to freeze things. Although, last time I used Mac OS X, browsing with Safari (I think a month or two ago), and used Java, it was fine. Maybe check your Firefox plugins and check that Java is going OK? -- Daverocks (talk) 10:25, 6 April 2006 (UTC)

Recharging Alkaline Batteries[edit]

Are alkaline batteries rechargeable? This website claims that they are. I remember seeing expensive batteries chargers a few years ago that wre supposed to be able to recharge ordinary batteries. --Username132 (talk) 20:04, 4 April 2006 (UTC)

The website and experiments seem pretty well thought out. I don't see any reason to doubt him. Obviously the manufacturers would warn you against this, both to cover themselves against you over-charging and getting acid on yourself, and because they'd be losing out on the sale of a battery. — Asbestos | Talk (RFC) 20:22, 4 April 2006 (UTC)
I've got an alkaline recharger. It's great when it works, but when it doesn't, the batteries leak inside the charger or, worse, in use. The problem is the utter randomness of the failure mode. Sometimes a battery lasts for dozens of charges, but the next battery of the same type goes splat on the first charge. It's not too bad for powering cheap devices like torches/flashlights, if you don't mind having to clean them out occasionally. I've also tried "rechargeable" alkalines. They barf less frequently, but the highly caustic stuff that comes out burns your fingers, and the slight extra reliability is not worth the risk and the higher cost. Now I use NiMHs in any device that costs more than the batteries, and they never fail. --Heron 20:28, 4 April 2006 (UTC)

Make database backup using phpMyAdmin[edit]

How do I make a database backup using phpMyAdmin for a mySQL database. I need something I can save on to a CD. Thanks Gerard Foley 21:32, 4 April 2006 (UTC).

The phpMyAdmin documentation (either distributed or online) is probably a better reference, but you're basically looking to export the relevant database(s) to files (compression is unlikely to matter if you're saving them to CD), making sure to export both structure and data. There may also be some form of "export all" function, but if so, I am not aware of it. — Lomn Talk 22:23, 4 April 2006 (UTC)
I found an export button, but I can't find where the file gets saved. Gerard Foley 23:27, 4 April 2006 (UTC)
Try this. --Fastfission 01:09, 5 April 2006 (UTC)

Doug Hall: What did he invent[edit]

Besides brainstorming processes and other business practices, what's this American Inventor judge's claim to fame? The average American house is supposed to have 18 of his inventions. Yet does this guy publish a list anywhere?

These are the only two relevant links I can find...

http://www.fansofrealitytv.com/forums/showthread.php?s=82a4ef00100cece6411be2fed9b8d48a&t=52829&page=2 http://www.eurekaranch.com/experience/

He's cited in two patent applications, through a "Personal Engineering" article, though not involved with them.[7] He's invented Eveready Lead Free Battery and Crystal Pepsi, but there's no other web references to him, it seems.

So... is he for real? -- Zanimum 21:41, 4 April 2006 (UTC)

A bit more information "Doug Hall began his inventing career at age 12, inventing and selling a line of magic and juggling kits. After earning a chemical engineering degree from the University of Maine, he joined Procter & Gamble, where he rose to the rank of Master Marketing Inventor -- inventing and shipping a record nine innovations in 12 months."[8]. That's about all the information you're going to get because:
"3. What are the 18 products or services in the average American home?
Sorry we can’t tell you. Our contracts with clients require us to remain silent even after the products are introduced.
The Eureka! Ranch business model is based on “contract inventing.” We are an invention think tank. We are paid a fee for our inventing as opposed to a royalty. We do our work under a “work for hire” agreement. This means that we are not named on patents and have no claim of ownership.
The basis for the claim of 18 products and services. In truth we have invented or helped reinvent many more than 18 – 18 is the average in each home. And that’s less than half of our work as the majority of our invention consulting work is for industrial and international companies.
The claim of 18 is based on a nationally representative survey conducted in 1996. The true number today is much higher. When you realize that we work for such clients as Procter & Gamble, Johnson & Johnson, Frito-Lay, Pepsi, American Express, Bank of America, Kraft, Ford, etc., it’s easy to understand how the numbers get so large – so quickly.
Invention Licensing: In addition, I’ve personally negotiated licensing agreements on behalf of clients with the National Football League, Major League Baseball, Parker Brothers, Henson Associates, Garfield & Friends and Random House." [9]. --Fuhghettaboutit 22:37, 4 April 2006 (UTC)
Thanks, I missed that FAQ. So there's no way to find out what he created. That really sucks. -- Zanimum 12:51, 10 April 2006 (UTC)

April 5[edit]

Canon Pixma MP780 troubleshooting.[edit]

I have a Canon Pixma MP780. It is an all-in-one printer (copies, scans, faxes, does photos, and prints). It is powered via a USB cable. Out of the blue, it has ceased to power on. The black (3e I believe) cartridge is full, but the cyan, magenta, yellow cartridges, and the other black cartridge is empty, although I don't think that has anything to do with the situation... What could be the cause? What can I do to solve this problem? Javguerre 02:10, 5 April 2006 (UTC)

Its likely not your ink, I don't want to sound like I'm stating the obvious but check your power cables. If you have a multimeter try checking to see if voltage comes out of the power supply. Let me know if those help, I can look up some more things to try if necessary :) -- Tawker 07:34, 5 April 2006 (UTC)

Try a different USB cable, and try it in a different USB port, or, if possible, on a different computer to elimate failure of your cable or computers usb ports. For great justice. 23:57, 5 April 2006 (UTC)

Dogs[edit]

Why do dogs run? Thanks. The pizzaman 19:03, 5 April 2006 (UTC)

To get to the other side. --Optichan 20:54, 5 April 2006 (UTC)
Faster. ☢ Ҡiff 01:34, 6 April 2006 (UTC)
Because they can. User:Zoe|(talk) 23:47, 5 April 2006 (UTC)
Because they are predators. Before they became lapdogs, they hunted in packs, and had to chase down prey in order to eat. Also, they had to run away from predators. It makes some sense that they are driven to run, even though they may not 'need' to anymore, it's such a part of their biology. For great justice. 23:49, 5 April 2006 (UTC)
No such thing as a dumb question? This is asking like why dogs can walk. -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 07:16, 6 April 2006 (UTC)

I smell a homework question, and I'll be darned if I'm going to devalue the education of a pre-pre-school student who thinks he can just hop on wiki refdesk for the answers to all his problems!!! --Jmeden2000 15:11, 12 April 2006 (UTC)

Multithreading in Fedora Core 4[edit]

I've successfully installed the second processor in my Proliant 3000, but things don't seem to be any faster than usual. Is there something I need to install or trigger to activate multithreading in Fedora Core 4? If a program wasn't designed for multithreading, can an OS split its requests up across two threads for faster processing? Is there a more suitable distribution to take advantage of the two processors (FC4 takes nearly 10 minutes to load). --Username132 (talk) 03:26, 5 April 2006 (UTC)

Is this an existing install of Fedora or a new one? -- Tawker 07:32, 5 April 2006 (UTC)
To take advantage of multiple processors, you need an SMP kernel. I believe that this is included in a Fedora install if the installer detects multiple processors; otherwise you need to install it yourself - Fedora RPMs definitely exist, and shouldn't be too hard to find (it's called kernel-smp or linux-kernel-smp or something like that). Once you've installed the RPM, you need to restart your computer.
As for the advantages, the only performance increase with most applications will be due to one processor handling the OS overhead while your application gets the other all to itself. Some programs (mostly scientific simulation software) can be recompiled to take advantage of double processors, but most desktop software can't. 61.48.162.166 11:26, 5 April 2006 (UTC)
When you say "things don't seem to be any faster" can you be specific about what you are measuring? It will be rare (though not unknown) for any *single* program to give greater throughput on multiple processors. Multiple processors benefit multiple programs. If a program wasn't designed for multi-threading, there is no magic available to make it multi-thread. Notinasnaid 11:37, 5 April 2006 (UTC)
What I meant was that it still takes about 10 minutes to load the operating system. --Username132 (talk) 19:03, 5 April 2006 (UTC)
Most Unix systems I've seen first run in the Kernel, single threaded. They spend a lot of time checking devices, which is not going to be related to the number or speed of CPUs. Then they start all the daemon processes. There is potential here to use dual CPUs, but the systems I have seen do not; they start them one after another, often with series of built in delays. So boot time isn't very much dependent on the kind of computer. What will improve it is removing unnecessary startup. A bold move would be to identify startup scripts which are independent of each other, and write a framework to multiprocess them. Maybe some Linux distributions have already done this. Mac OS X has done this. Notinasnaid 20:05, 5 April 2006 (UTC)

Basically, it will be noticeable if you run more programs at the same time or, reconfigure some of your software. Unless you get like an quad-core apple, and actually run alot of stuff at once, they are useless IMO, nice bragging rights though!

Nitroglycerin[edit]

I will take this time to ask a foolish question, could Nitroglycerin be used in propelling a craft pecifically a spaceship?

  • Not a spaceship: the chemical formula for nitroglycerin is C3H5(ONO2)3. When exploded, it combines with oxygen to form the stable carbon dioxide, water and nitrogen molecules. The vaccuum of space, having very little oxygen with which to react, can't support the reaction. Even in within the atmosphere, however, propulsion with something as terribly unstable as nitroglycerin is a very bad idea: pure nitroglycerin is so reactive that it has been known to explode after receiving even the tiniest of jolts, or even by changing temperature by as little as 1 degree too quickly. Nasty stuff. – ClockworkSoul 03:49, 5 April 2006 (UTC)
To explode nitroglycerin does not requires oxygen (or anything else). Pure nitroglycerin is too unstable to be used as rocket fuel. -Yyy 06:12, 5 April 2006 (UTC)
I can't see any reason to think it would be a particularly good fuel even if stability weren't a problem. High explosives don't have particularly high energy density; they just release it very very fast. --Trovatore 06:25, 5 April 2006 (UTC)
Just for the record, fuel+oxygen reactions are used in rockets, commonly in fact. See liquid oxygen. --Bth 12:44, 5 April 2006 (UTC)
That's true, but rockets bring the oxygen with them. – ClockworkSoul 13:56, 5 April 2006 (UTC)
Solid rocket fuel contains all the necessary oxygen within itself and does not rely on additional atmospheric oxygen. It is a relatively simple recipe. You may want to check out some of the amateur rocket sites if you are curious about the properties, stability, ranging, and targetting of such devices. Ande B 22:23, 5 April 2006 (UTC)
Unless you're using a Hybrid rocket. Solid fuel+gaseous/liquid oxidizer. Nitroglycerin is a liquid anyway. Night Gyr 17:39, 7 April 2006 (UTC)
Hybrid, now that's cool! I always found it ironic (as have many others) that nitroglycerine, combined with a few binders to make a nice little pill, could keep the heart from exploding. Ande B 01:53, 8 April 2006 (UTC)
  • Nitro would be unsuitable as a rocket fuel mainly due to its instability. The instant you lit off the engine, the shock would set off a sympathetic detonation in the rest of the supply. Also, explosions are less efficient than a steady burn due to the danger of damaging the ship and corresponding need for stronger (i.e. heavier) engines and nozzles. Night Gyr 17:39, 7 April 2006 (UTC)

How is modulation diffrent from multiplexing?[edit]

this is regarding networks communication,i am always getting convuse between these words,can u plz make it clear, it would be so great and thankfulll to u .thanks a lot --- viv

If I'm reading correctly the main difference is modulation uses one channel whereas multiplexing uses multiple channels.

In telecommunications, multiplexing (also MUXing) is the combination of two or more higher level channels into a single lower level channel such that a reverse process, known as inverse multiplexing, demultiplexing, or demuxing, can extract the original channels. The individual channels are identifiable by a predetermined coding scheme.

vs

Modulation is the process of varying a carrier signal in order to use that signal to convey information. The three key parameters of a sinusoid are its amplitude, its phase and its frequency, all of which can be modified in accordance with an information signal to obtain the modulated signal. There are several reasons to modulate a signal before transmission in a medium. These include the ability of different users sharing a medium (multiple access), and making the signal properties physically compatible with the propagation medium. A device that performs modulation is known as a modulator and a device that performs the inverse operation of demodulation is known as a demodulator. A device that can do both operations is a modem (a contraction of the two terms).

Cheers -- Tawker 07:31, 5 April 2006 (UTC)

Thin[edit]

If you thickened something with starch, is there anything easily available to thin it a bit? 57.66.51.165 10:18, 5 April 2006 (UTC)

Did you try water?--Adam (talk) 16:20, 5 April 2006 (UTC)

According to some places, that makes it thicker owing to the grains swelling. Plus, I kind of need it concentrated. 57.66.51.165 16:23, 5 April 2006 (UTC)

It's possible that if the mixture is so thick that the starch is not fully disolved, that might be true, but then you would have a really thick paste, almost a solid. Water is the way to go I'm afraid. For great justice. 23:47, 5 April 2006 (UTC)

Small switching PSUs 400 VAC -> 24 VDC[edit]

Hi, I'm trying to find someone selling small switching PSUs (for mounting in an enclosure). Wanted voltages: 400 VAC->24 VDC. I haven't found anything with a lower power rating than approximately 100 W, and most of them are quite bulky (the smallest side can't be bigger than 65 mm or they won't fit). There are loads of alternatives for 230 VDC voltage though. Does anyone know of a suitable inexpensive alternative, available in northern Europe/Scandinavia? 62.119.184.141 12:20, 5 April 2006 (UTC)

If I were trying to get hold of a not-so-common component like that, I would try RS[10] or Farnell[11] (both links are to their lists of national sites) both of whom generally have a good range. Or if you have a regular supplier who doesn't list what you're looking for, have you tried asking them if they can order something for you specially? -- AJR | Talk 19:16, 5 April 2006 (UTC)
I had already tried Farnell, didn't find any. I tried RSComponent as well - my search for "PSU 400VAC 24VDC" didn't get any answers (except partial matches - there are lot of 24VDC PSUs). And a custom-made solution isn't really in the question I think - the number of units needed is pretty small. 62.119.184.141 09:51, 7 April 2006 (UTC)

Question about human bodies.[edit]

dear sir/madam, I would like to know, what makes the best lubricant to smear on my penis. i have tried sunflower oil, but my girlfriend says that it burns too much. This may sound juvenile, but I really have a problem. Thank you very much for your time,

--86.16.167.4 15:09, 5 April 2006 (UTC)

There are many products specifically designed for that. You might want to look at personal lubricant. --Ed (Edgar181) 15:14, 5 April 2006 (UTC)
Assuming you are a young couple, my first impression is you are not taking your time with her enough. If you have plenty of foreplay you should not need a lubricant, as her sexual arousal will be enough to provide that.
You may be right but many young women actually need the assistance of a lubricant and should not feel that they are somehow "inadequate" because of that. There are plenty of good water based or silicon based alternatives to oil so that the couple can experiment with a number of them to get the right one for their life styles. Ande B 22:32, 5 April 2006 (UTC)
Right. Maybe he's talking about anal sex?... —Keenan Pepper 17:25, 5 April 2006 (UTC)
Then he should say so, there are different considerations for such activity. He may want to check out the alt.sex.faq that was developed quite some time ago but is still fairly comprehensive. Ande B 22:32, 5 April 2006 (UTC)
"alt.sex.fag"?
grin. No q not g. - Mgm|(talk) 12:34, 6 April 2006 (UTC)

Cockpit Automation Philosophy[edit]

Sir or Madam, I am currently writing a graduate-level paper on the differences between the cockpit automation philosophies used by Boeing and Airbus and am attempting to locate greater factual and/or 'learned opinion', vice the readily-available lay-opinion comparing the two. Any assistance would be greatly appriciated; thank you in advance.

All I can offer is one of those readily available lay-opinions: There is concern that a high level of automation will lead the pilot and copilot to pay less attention, thus causing more accidents. However, this is really just a specific example of one of the problems inherent in human interaction with fault tolerant design (where the "faults" are caused by inattentive humans). StuRat 17:43, 5 April 2006 (UTC)
You're looking in the wrong place. You need to spend some time with tools like Google Scholar and Web of Knowledge to see what's in the academic journals. A search for "Boeing cockpit automation" in those places turns up dozens of relevant papers. --Robert Merkel 05:17, 6 April 2006 (UTC)

GRR... My upload bandwidth sucks...[edit]

I've noticed that anything that a ISP would sell you has a terrible up-down ratio (excluding SDSL, but that tends to have lower downspeeds). Where do the ISPs get all their bandwidth?--Frenchman113 19:19, 5 April 2006 (UTC)

Er, this doesn't answer your question, but to my understanding the sum of up + down bandwidth is limited by the quality (i.e. price) of your and their DSL/cable equipment. Since most people are doing things like web browsing and email that don't upload much, the ISPs emphasize download speeds at the expense of the up. For completeness, the answer to what you actually asked is that ISPs rent bandwidth from bigger providers upstream of them (like UUNET) just like you rent it from them. Eventually you reach one of the backbone providers like Level 3 who own the biggest pipes and effectively "make" the bandwidth. --Tardis 20:37, 5 April 2006 (UTC)
Right. But say one was feelthy rich and could lay one's own data link between continents. What would it take to become a 'Backbone' provider? Is the difference determined by who sells bandwidth to who? 08:31, 6 April 2006 (UTC)
As to why upstream is slower: I like the picture in ADSL. That's just how frequency allocation has been made. To get a symmetric line: call your local telco providers, they are likely able to lease you a line. That is what most companies do when they want a high volume web site etc. Expect to pay 10x-100x what you pay for ADSL per month (more for really fat pipes). To lay your own lines: consult local legislation; you may need to form a company that is a certified telco provider. Sure that is possible if you have the cash; most telcos are private companies.
For most home users the ADSL or cable modem the local telcos offer is pretty much the best price/speed point you can get. If there was a magical way to offer faster service some company would have already done that and wiped the competition off the Earth. Market economy in action... Weregerbil 11:06, 6 April 2006 (UTC)

From AIDS back to HIV[edit]

I was wondering if the drugs we have today for HIV patients are so good that they have the ability to make the HIV virus undetectable in the human body, they why can they not bring back a patients with AIDS back into HIV+ status?

HIV+ is a different mode of operation of the virus -- a dormant phase with no symptoms whatsoever. I imagine that "undetectable" HIV is simply small numbers of viral particles, which can easily grow back to large numbers if the treatment is removed or becomes ineffective. In other words, HIV+ is a different kind of infection, whereas these drugs only change the amount of it (and not to 0). But I am not a pathologist at all... try reading the pharmacological information associated with the drugs? The FDA might have some relevant information. --Tardis 20:46, 5 April 2006 (UTC)

O4[edit]

Have molecules composed of four oxygen atoms been produced? What's up with them?

In theory, one could have
O-O
| |
O-O

and fulfill the octet rule requirements. Cyclobutane has this structure (with hydrogens), for instance. But it strains this type of chemical bond to adopt a 90° angle, so it would almost certainly be unstable and fall apart into two normal O2 molecules. --Tardis 21:09, 5 April 2006 (UTC)

Tetraoxygen does indeed exist at very high pressures. —Keenan Pepper 21:12, 5 April 2006 (UTC)
There's N4 as well. I'm not sure anyone actually knows if O4 has a cyclic structure though. --BluePlatypus 23:31, 5 April 2006 (UTC)
My proposition about O4 : since we know that O 2 is paramagnetic, before people can make the high magnetic field, it is anti-magnetic,why don't you try to make the experiment as follows:

- Use two tanks which can sustain a high pressure, a tank contain O2, another is empty, and maybe waccuum Join two tanks by one tube + one siphon + one tube ; ( siphon has the diameter bigger than the tubes); in middle of the siphon,place one thick steel frame which can sustain a high pressure, drill many pores( its diameter is super small as possible) on the steel frame , around the siphon, apply the highest magnetic field with about 60MOe, and then press the O2 in first tank thru the siphon, I think that you can get O4 in the second tank,this is my own opinion, I don't have any equipment for this experiment. If you have the condition to make it, please let me know the result. Or if you have the stuck, I have the time to suppose again . --User:Ngocthuan 06 23:08 , 6 April 2006 (UTC)

Galileo[edit]

My question is easy, but i just can't find answer :( What is the well-known phrase, associated with Gelileo Galilei? "Yet it spins", "Still it rotates" or how? Just i'm not native english speaker, and never interested of it in english. Thank you. ellol 21:48, 5 April 2006 (UTC)

It's not mentioned explicitly in his article but it is linked in the 'see also' section. He was, apparently, forced to recant his heliocentrism, but muttered E pur si muove! - "And yet it moves" - under his breath. --Hughcharlesparker 22:08, 5 April 2006 (UTC)
Sorry. Right. Thank you! ellol 03:24, 6 April 2006 (UTC)
Yes, but this is most likely apocrophal. I mean, he might have said it under his breath (we really don't know), but he was effectively shut up about it. For great justice. 23:42, 5 April 2006 (UTC)

isotopes[edit]

the time it takes for one half of the amount of an isotope to decay to nonradioactive form is it's__________?

Half-life. --Someones life 23:02, 5 April 2006 (UTC)
Half-life = how much of my time I spend reading obvious homework questions. StuRat 08:23, 8 April 2006 (UTC)

Constitution font[edit]

On Mac OS X, is there a free font that evokes the kind of script used on old copies of the US constitution? It doesn't need to be exact, or historically accurate, but just evoke that kind of 'feel'. Thanks! For great justice. 23:36, 5 April 2006 (UTC)

Zapfino is an incredibly flowing cursive font. It should be suitible for what you are doing. --Serie 00:06, 6 April 2006 (UTC)

Wooaaahh! That IS cursive! That's definately the puppy! Thanks! For great justice. 00:07, 6 April 2006 (UTC)

April 6[edit]

Adhesive bonding[edit]

I've asked a few questions on Talk:Adhesive without many satisfactory answers. I would like to know, for example, if I glue two pieces of polished steel with cyanoacrylate glue, how much of the bonding is chemical and how much is mechanical. I am inclined to think that it is largely a chemical bond, but if so, what is the bond involved? —Ben FrantzDale 02:59, 6 April 2006 (UTC)

I don't think you could give an exact number for that. I'd think cyanoacrylates would mainly be considered to bond mechanically, polymer glues in general work by filling out the surface area while a liquid and then reacting to form a solid polymer. Chemical compounds in general don't bind very well to metal since the metallic bond is a bit of a different animal from most. It can still bind by chelating to the metal atoms on the surface, probably through either the cyanate or carboxyl groups. However, those bonds would be weaker than in the cases where an adhesive can form hydrogen bonds with the surface. --BluePlatypus 05:13, 6 April 2006 (UTC)

Photographic Memory[edit]

Although the eidetic memory page is certainly informative, I'm not quite clear on what answer is arrived at. Is there, or is there not, such a thing as photographic memory as it is commonly portrayed? By that I mean innate, photographic (actually a snapshot, rather than based around important features like 'red shirt' and 'a bit to the left'), essentially effortless, and durable. If not, why is there so much popular certainty that such people exist? Black Carrot 03:28, 6 April 2006 (UTC)

This is from my own incredibly shaky memory, so may not be totally accurate, but from what I recall people actuallt do take in most of the items in a scene, but the linkage between short-term and long-term memory is better in some people than others; also some people are better able to retrieve items from their long term memory. It's not that some people have photographic memory where others don't; it's more that some people are better able ot store and access whatever memories they have received. Because some people can perform very well in such memory tasks, it is popularly assumed that some "super-special" memory is present in some individuals, shich is why the idea of photographic memory is so prevalent. Anyone able to confirm or deny...? My specialy was perception, not cognition :) Grutness...wha? 07:58, 6 April 2006 (UTC)
On the off chance it jogs a memory, the only article I can remember ever reading that mentioned photographic memory existing claimed that, when people with such memory (which they apparently could get hold of enough of to do this test) forgot a picture, which did happen over time, it 'shattered' or 'fragmented' or some such rather than becoming vaguer and less detailed. Anyone recognize this? Black Carrot 04:27, 9 April 2006 (UTC)

The period validity of the patent[edit]

The period validity of the patent of the fuel saver by magnet treatment is invalid.Is’nt it ? Wiki? Ngocthuan 06 11:08, 6 April 2006

   U.S. Patent 3,830,621 - Process and Apparatus for Effecting Efficient Combustion.
   U.S. Patent 4,188,296 - Fuel Combustion and Magnetizing Apparatus used therefor.
   U.S. Patent 4,461,262 - Fuel Treating Device.
   U.S. Patent 4,572,145 - Magnetic Fuel Line Device.
   U.S. Patent 5,124,045 - Permanent Magnetic Power Cell System for Treating Fuel Lines for More Efficient Combustion and Less Pollution.
   U.S. Patent 5,331,807 - Air Fuel Magnetizer.
   U.S. Patent 5,664,546 - Fuel Saving Device.
   U.S. Patent 5,671,719 - Fuel Activation Apparatus using Magnetic Body.
   U.S. Patent 5,829,420 - Electromagnetic Device for the Magnetic Treatment of Fuel.

I don't know the dates of these. For great justice. 04:27, 6 April 2006 (UTC) The Inset Fuel Stabilizer [12] appears not to be patented. For great justice. 04:29, 6 April 2006 (UTC)

It seems that we don't have articles on fuel saving gadgets, magnets round the fuel line or in the air flow (Ecoflow, FuelMAX, FuelSaverPro, etc), catalysts in the fuel line or tank (Broquet, Fitch Fuel Catalyst, Prozone, Fuelstar, etc), platinum-based combustion enhancers (PVI, Gasaver, Ctech3000, etc), ignition enhancers (Fuel Saving & Power Push, Fireball Ignition, etc, air bleed into the inlet manifold (Ecotek, Khaos, Powerjet USA, etc), turbulence increasers (Ecotek, Tornado Fuel Saver, Powerjet USA, SpiralMax, etc), devices to "atomise the fuel better" (Ecotek, Tornado, SpiralMax, Vaporate, etc), oil additives (Slick 50, Duralube, etc), fuel additives to enhance combustion (Acetone, PowerPill, BioPerformance, etc), engine "cleaning" products (10k Boost, Powerboost, etc), electrical modifications (grounding straps, voltage stabilisers, etc) or hydrogen generators. Shame. For great justice. 04:35, 6 April 2006 (UTC)

In a slightly less oblique way, For Great Justice is suggesting that patent or no patent, the evidence that any of these devices actually work is extremely thin to nonexistent, particularly the ones related to magnets. See snake oil. --Robert Merkel 04:57, 6 April 2006 (UTC)
Absolutely - although actually, I think an article on these devices wouldn't be a bad idea - explaining the science of why they can't work would be a worthwhile excercise. What would the name of the article be though? Is there a generic word for these? For great justice. 05:06, 6 April 2006 (UTC)
Aside from "junk", I don't think so. To be fair, injector cleaners don't quite belong here, in certain specific circumstances they can actually be useful. Subaru actually recommends the periodic use of one for my Subaru Impreza WRX.
But as to the broader point, how about fuel economy accessories, or something like it? A survey of the devices and their purported mechanisms of action would be quite useful. --Robert Merkel 05:11, 6 April 2006 (UTC)
Fair point on injector cleaners. I still think there's some milage in the phenomenon of snake oil as applied to fuel economy magnets - perhaps only as a section of snake oil though. These aren't really just accessories though - the point is that they are completely spurious... For great justice. 05:18, 6 April 2006 (UTC)
I have been found out the magnet treatment around the fuel pipe from many years ago, but I think that it is the minimium magnetization, because it is very easy for locating the magnet lying perpendicular to another and first and foremost all of the magnets are perpendicularly to the fuel pipe, this thing is the same meaning that they cause the magnetic line perpendicular to the fuel pipe.
   The magnetic Flux = B * S * cos (B,n)
   Here , cos (B, n) =0 ( n : the direction perpendicular to S; i.e: normal line of Surface S)
   For the maximum magnetization , cos (B,n) must be equal to 1

I.e.: the magnetic lines was caused by these magnets which are paralell to the fuel pipe.

   For this raison, we can reduce the volume of the magnets, and follow to their weight shall be reduced noticeable .
   Another raison, many peoples don't like to use word wrap is because the peoples that don't use it like to force a horizontal scroll bar into your web browser. even the powers of wikipedia and firefox combines cannot wrap the text.
  Ngocthuan 06  16:25, 6 April 2006 (Vietnam)

Atmospheric pressure (can someone source this for me?)[edit]

An anon added the following to a (featured) page I watch: "Where an atmosphere is less than 0.006 Earth atmospheres water cannot exist in liquid form as the required atmospheric pressure, 4.56 mmHg (608 Pa), does not occur." I didn't see this specific point on the atmospheric pressure page and I don't know an mmHg from a bowling ball. Hoping someone could point to a source. Marskell 08:26, 6 April 2006 (UTC)

It's the pressure at the Triple point of water. --BluePlatypus 08:33, 6 April 2006 (UTC)

red mercuy[edit]

Dear Sir is red mecury rs 99.999 can be used in medisence or not

I believe the idea is, that if Red mercury existed (which it doesn't), it could be used in an atomic bomb. --BluePlatypus 08:35, 6 April 2006 (UTC)
I think you are referring to mercurochrome which can be used as a topical antiseptic. - Cybergoth 03:21, 7 April 2006 (UTC)

Ewww, what the hell popped out of that earwig?[edit]

Hoping someone knowledgeable in earwig entomology can answer this. I just squished an earwig on the wall with a tissue. While pressing down on it (I had to squish it fast but it took a bit of finger-strength to get it to actually squish) there was a sound not unlike a clicking sound.

I take the tissue off the wall and there's two things -- the earwig's corpse, dead but intact. And then there was something else, it was a dark color and with a shape that an eggplant might be if you were to bend it in the middle 90 degrees. I'm guessing it was either something fecal or was it perhaps an egg it was carrying? Perhaps some inside body part of the earwig? Either way it convinced me that killing an earwig is an ickier experience than merely being in the presence of an earwig, and next time I'll capture one in a jar and let it loose in my neighbor's yard instead.

Just what in the world popped out of that earwig when I squished it? It wasn't even messy, just a solid object with no real "splatter" to it. --209.77.244.12 09:39, 6 April 2006 (UTC)

I heard that earwigs have two penises in case one breaks off during sex. So maybe what you saw was its spare penis. Ah, our article on earwig has that fact as well. You might find some more stuff in that article that might help you. -- Daverocks (talk) 10:21, 6 April 2006 (UTC)
The earwig article doesn't actually have a whole lot on earwig anatomy. Shame. For great justice. 18:00, 6 April 2006 (UTC)
Also. WTF happened? Compact Flash cards are now the new standard for size comparison? Come on! Only on Slashdot, surely - what happened to a ruler, or something?! For great justice. 18:03, 6 April 2006 (UTC)

Nuclear engineering[edit]

How is it possible to get highly enriched uranium from a centrifuge?Wont that Uranium possess critical mass and undergo fisson?What initiates criticality accidents?

The uranium first goes through some processing which converts it to uranium hexafluoride. This is a gas, and its density is rather low compared to solid uranium, so criticality isn't so much of an issue here. --HappyCamper 11:16, 6 April 2006 (UTC)
Have a look at Zippe-type centrifuge. The details of the various designs remain a closely-guarded secret. --Robert Merkel 23:17, 6 April 2006 (UTC)

El Nino and La Nina[edit]

Hello, I am writing an article for my high school newspaper about El Nino and La Nina because I read somewhere that we are just leaving a La Nina year and entering an El Nino year. Is this true, because the Wikipedia article doesn't say that. Thanks for your help!! Zach 10:42, 6 April 2006 (UTC)

The Australian Bureau of Meteorology's climate page has extensive information about the current state of ENSO. --Robert Merkel 23:20, 6 April 2006 (UTC)

Mermaid[edit]

Hi,

Does mermaid exist?--Aju 11:07, 6 April 2006 (UTC)

Nope. How old are you? Loomis51 21:52, 6 April 2006 (UTC)

Irrelevant. Misinformation can strike at any age, though generally we learn to guard against it better over time. Tzarius 09:07, 7 April 2006 (UTC)

To a very lonely sailor, a manatee can look like a mermaid. StuRat 08:14, 8 April 2006 (UTC)

Silicon Wafers[edit]

I've got a question about the surface of a silicon wafer. Do you get an silicon dioxide layer on the surface? If so, what kind of thickness might you expect? If not, what does the surface of a silicon wafer (outside of the cleanroom environment) look like? 12.106.14.201 14:36, 6 April 2006 (UTC)

It looks pretty much like a (somewhat dark) mirror. Imagine this sliced up. You won't get an oxide layer at room temperature, you have to grow them at high temperature to the desired thickness. Current research involves MOSFET gate oxides with thickness < 10 nm. - mako 02:14, 7 April 2006 (UTC)

APOLOGY[edit]

Hello! It’s me Nita .I am going to write an assignment about Feasibility report.I am totally ignorant of this term. I had already sent a question to u n u people replied it too. I confessed that I had committed some mistakes that’s why I am sending you an informal apology .I beg your pardon sir,hope you will ignore my mistake. I admit it that my English is not proper but you people will have to accept the fact that on the face of this earth a lot of nations with different languages are residing and none can snub a person on the plea that he is speaking or writing wrong English .I know four languages .ENGLISH, URDU, HINDI, FRENCH and PERSIAN .I guess its enough for a girl who is just 17 .my purpose of sending u this mail is just to give u this explanation that ; I am sorry for using wrong grammar ,I am sorry for not saying PLEASE .now may you tell me what is feasibility report .I am not asking you to make my whole assignment I am just asking for a little assistance so that I may be able to fulfill my task properly —The preceding unsigned comment was added by 203.99.61.48 (talkcontribs) 14:37, 6 April 2006 (UTC) Thank you.

When touring a strange land, it is best to have a guide, or to learn the local customs. That way, people won't be rude to you. Here, we have the equivalent of a guide at the beginning of this document, and it is best to read it. --Zeizmic 14:47, 6 April 2006 (UTC)
A feasibility report describes whether something can be done or not, how easy or hard it will be to do, etc. Search for the term on google and you will find hundreds of examples of them. Chapuisat 14:52, 6 April 2006 (UTC)
No, I don't think that's true. "Feasible" is different from "possible". For something to be feasible, it has to be something that can be reasonably accomplished within practical constraints, particularly economic ones; it's not enough for it to be possible in theory. That said, there is a minority usage which uses "feasible" synonymously with "possible" (makes my skin crawl, personally; it's as bad as "refute" meaning "deny"). But that usage is unlikely to be the one intended in something called a "feasibility report". --Trovatore 23:04, 6 April 2006 (UTC)
Not sure why you think you're disagreeing with me. That's exactly what I was saying it was. "whether something can be done or not, how easy to hard it will be to do". So a report might come back and say "it can't be done" or it might say "It can be done but it will take 3 years and $400,000 and require extensive paperwork", or maybe "It will cost $0.75 and a trip to the hardware store". Anyways, the best way for the original poster to understand would be to google "feasibility report" and read through some examples. Chapuisat 13:33, 7 April 2006 (UTC)
Huh? Saying it will take 3 years and $400,000 is information about how hard it is to do, not about whether it can be done or not. As far as I can see you're contradicting yourself in the space of two sentences. --Trovatore 19:59, 8 April 2006 (UTC)
Whoops. My eye seems to have interpolated a "not" that wasn't there. I read it as "whether something can be done or not, not how easy or hard it will be to do. --Trovatore 20:22, 8 April 2006 (UTC)

In the case of a feasibility report on an investment, an important indicator of how good the investment would be is the return on investment. This can either be given as a percentage or number of years. For example, if it costs a million dollars to build a bagel factory, and it can make 200,000 dollars in profit a year, that's a 20% ROI or 5 years to pay off the original investment. That would be considered to be a good investment. StuRat 08:09, 8 April 2006 (UTC)

A more general way to evaluate feasibility would be a cost-benefit analysis. The opportunity cost should also be considered. StuRat 22:41, 11 April 2006 (UTC)

Hi Nita, the link to Feasibility report, which was a redirect to Feasibility study has just been fixed. Probably you should ask your teacher what is expected of you though, it's not clear what you want to know. You say "I know four languages .ENGLISH, URDU, HINDI, FRENCH and PERSIAN." That's very impressive. Do you count Urdu and Hindi as one language because they are so close? GangofOne 23:01, 11 April 2006 (UTC)

Software to record data through the sound card[edit]

Does anyone know any piece of software to record everything that sounds through the speakers? Something like "redirecting" the data to a file. For MS Windows and GNU/Linux also, if possible. Thanks. --GTubio 14:58, 6 April 2006 (UTC)

I know there's something for the Mac, and I'm sure there is for the PC or Linux, but don't know what it is - would Audacity meet your needs? For great justice. 17:24, 6 April 2006 (UTC)
On windows, double click on the speaker icon, go to Options -> Properties, select the option "Recording" and on that list, enable all checkboxes that has something to do with "out" ("Stereo Out", "Mix Out", "Stereo Mix" or something like that). Click ok. The slide bars will change for recording volumes, and below each one there's a checkbox. Mark one of the outs and just hit record with any program, one of them will work. ☢ Ҡiff 18:45, 6 April 2006 (UTC)
The standard "low-tech" solution is to get a lead with 3.5mm stereo plugs on either end, plug one end into the output from your soundcard, and the other into your input or microphone socket. And then use Audacity to do the actual recording, as others have mentioned. Ojw 19:55, 6 April 2006 (UTC)

Thank you very much to all. --GTubio 08:12, 11 April 2006 (UTC)

Interconnection[edit]

If you connect a simple device designed for 240 V/ 50 Hz (like a British hairdryer) with an adapter to 110 V / 60 Hz (like America), will it work? Will the higher frequency damage it? 57.66.51.165 15:24, 6 April 2006 (UTC)

No, it wont work....for a long time atleast.... The fuse will probably burn up..if it has a fuse... otherwise the whole device would blow up... :-D ..... Jayant,17 Years, Indiacontribs 16:05, 6 April 2006 (UTC)
Well, you can get pretty cheap transformers that will convert the voltage. I have one, but frankly, if you only want a hairdrier, it would be cheaper to buy a small US hairdrier. For great justice. 17:21, 6 April 2006 (UTC)
It won't work, but putting a 240V device in a 120V (the actual US voltage standard) does not, if I recall correctly, cause spectacular failure. The device just doesn't get enough voltage to do anything meaningful. Now, overvolting a 120V device in a 240V outlet... that will cause sparks to fly. As for frequency, damage is unlikely in either direction. — Lomn Talk 17:23, 6 April 2006 (UTC)
If you plug a 60Hz device into a 50Hz socket, if it's got a transformer or coil somewhere in the circuit (most devices except incandescent light bulbs do), the lower frequency can cause the coil to saturate and become effectively a short circuit, quite possibly leading to a fire. --Serie 22:08, 6 April 2006 (UTC)
Having moved around a lot between both sides of the Atlantic, I can confirm most of the above (haven't played much with frequency-sensitive stuff), but wanted to warn about transformers: firstly, they only convert voltage, not frequency, so a 120 -> 240 transformer used in the US will produce 240V 60Hz (not 240V 50Hz, like in Europe) electricity - be warned for frequency-sensitive appliances, they might well go wonky (basically, anything complex). Also, transformers have a maximum wattage rating - a small one might be 50W or 100W, check the label. While this is fine for most small appliances, be warned of anything that produces lots of heat (toaster, hairdryer...) - these use massive amounts of power (a medium-sized hairdryer is often 1000W, check the label), and these will blow your transformer in very short order. I agree with For Great Justice, get yourself one of those 'travel' hairdryers (often sold at airports) which have a voltage selector switch for 120 / 240. — QuantumEleven | (talk) 12:14, 7 April 2006 (UTC)

Orbital feasibility of Counter-Earth[edit]

According to the article the orbit of a Counter-Earth (a planet always on the other side of the sun from us) is just feasible. So would somebody please point out what is wrong with this analysis:

Consider the earth at the point where the line joining it to the sun forms an exact right angle with the major axis of its orbit. Counter-earth must be at the opposite side of the sun, at the point where it's line to the sun also forms a right ngle with the elliptical axis.
Now let us advance the earth until it is in the same position on the other side of the sun - i.e. the other point where it's line to the sun forms a right angle with the elliptic axis. In order for counter-earth to still be hidden it must now occupy the position that earth previously occupied. BUT this cannot be the case, because by Kepler's second law the areas swept by the arcs must be identical, and this is obviously not the case (one of the planets must be going round the long side of the ellipse).
So is counter-earth orbitally feasible or not? DJ Clayworth 20:30, 6 April 2006 (UTC)
Well, the counter-earth theory doesn't (or shouldn't) say that counter-earth is always 180° offset from Earth, but rather that it is so nearly so that it is permanently occluded by the sun. There's allowance for wiggle room in the orbit proportional to the apparent size of the sun. However, since counter-earth is effectively debunked by observations of other planets, I'm not going to bother to work out the math on this one. — Lomn Talk 21:04, 6 April 2006 (UTC)
This was my first thought when seeing the problem above, however, as Melchoir pointed out, there is no requirement that Earth2TM needs to orbit on the same elipse. If the ellipse were rotated 180° for the other planet, then the instataneous velocities of the two would always be opposite and a line could be drawn connecting the planets and sun at each point in the orbit. So Kepler's Laws don't seem to prevent such a situation, but it's really a 3 body problem. The Lagrangian point article mentions L3 as a possible place for Counter-Earth, but doesn't say whether or not the system would be stable with two approximately equal masses. Maybe the maths reference desk would be able to help out? EricR 22:50, 6 April 2006 (UTC)

I think if the Hand of God were to place 2 perfect earth copies around a single sun, then it might be stable for a few million years. But instabilities, such as solar flares and giant meteors, would soon knock them out of perfect alignment. The formation of a Solar System is horribly unstable, and single planets sweep out their full orbital band. --Zeizmic 21:06, 6 April 2006 (UTC)

Meteors schmeteors. The counter-earth would have to have a moon exactly the same size as ours, and at exactly the same distance from its primary, and at exactly the same point on its orbit as ours at all times, created at exactly the same moment - otherwise the two orbis would get out of synch very quickly. And given that the moon was most likely caused by a chance collision of a proto-planetary body with the earth, the chances of that happening are probably about as good as going down to the beach and finding a grain of sand with your name and address carved on it. Grutness...wha? 00:59, 7 April 2006 (UTC)
And, as a final nail in the coffin, we have several satellites in solar orbit (mostly used for observing the sun), these would have spotted the Earth2TM already if it was there. — QuantumEleven | (talk) 12:07, 7 April 2006 (UTC)
Ah, yes. It had not occurred to be that there was a different ellipse that might satisfy the conditions. And no, my question was not intended to imply I thought counter-earth might exist. Thanks for your help. DJ Clayworth 15:42, 7 April 2006 (UTC)

Lead and its history[edit]

I am doing a research a report about lead and am having trouble finding out about leads history. ANY information would be helpful.

If you typed "lead" into the search box on the left of this page, you would have found our article on lead. --Robert Merkel 23:24, 6 April 2006 (UTC)

question on animal species[edit]

Out of all the animal species in the world, what animals are most abundant? The percentage?--24.147.235.177 21:57, 6 April 2006 (UTC)

You mean the most individual animals or the greatest total mass? —Keenan Pepper 00:19, 7 April 2006 (UTC)
  • It would be something small like ants or bacteria (though I can't remember if bacteria are part of the animal kingdom). - Mgm|(talk) 10:33, 7 April 2006 (UTC)
  • if you don't count bacteria as animals, nematode worms are a good candidate Malcolm Farmer 09:39, 11 April 2006 (UTC)

Journal Article[edit]

Where can I find the article: " On a supposed proof of a theorem in wave motion" which was written by G.J.Stoney, and published in the Philosophical Magazine in 1897 Vol.5 No.43? I am not sure if I will be able to find the place where your response will be posted, and I don't care if the whole world knows my e-mail address, I get lots of junk mail anyway. So if it's possible, send any information you find,to me at newage@uniserve.com Thank-you Thos

Unfortunately, I can't find an online copy. (JSTOR doesn't have it.) Your only recourse might be to find a substantial university with an old collection. It's actually quite remarkable how many universities have these incredibly interesting historical journals in the open stacks. (Incidentally, be very gentle with the old documents if you do find the paper. Stuff from the turn of the last century may or may not be in good shape, depending on the paper and binding. You might want to ask for assistance from the library staff before you try to photocopy old bound journals—making copies can be very hard on their spines.) TenOfAllTrades(talk) 00:06, 7 April 2006 (UTC)
Yeah, can't find it either. Its too old. -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 01:34, 7 April 2006 (UTC)
I presume this is a US journal? If so, a copyright library might be your call of last resort. For great justice. 02:01, 7 April 2006 (UTC)
If the homepage of the journal (here) doesn't have it (which it doesn't), then it's most likely not scanned or available anywhere at all online. Most journals don't have online archives that go back farther than a decade or two. Anyway, what you need to do is check with your local research/university libraries to see if they have it (their catalogs are usually online). If not, you can usually have a photocopy of the article sent to you from a library that does, for a small fee (say $5 or so). --BluePlatypus 04:50, 7 April 2006 (UTC)
I can probably get you a copy of the article early next week, as my university seems to have it available pretty easily for scanning. Let me see what I can do. Also, the title of the magazine from that era was, to be specific, The London, Edinburgh and Dublin philosophical magazine and journal of science. What a mouthful. --Fastfission 12:13, 8 April 2006 (UTC)

Downloading the Yahoo! Toolbar[edit]

When I try to download the Yahoo! toolbar, I am led to the MSN Search engine site without my permission, and, of course, no download takes place. This happens no matter how many times I try again.

Here is the sequence of links

  1. http://toolbar.yahoo.com/config/slv4_page?.p=featureantispy&.cpdl=net06
  2. http://toolbar.yahoo.com/config/slv4_done?.act=3&.dflt=1&.intl=us&.region=us&.partner=none&.guest=&.cpdl=net06&.mf1=as&.xpsp2=1&.data=
  3. http://search.msn.com/results.aspx?q=us


Also, under the subject category of Science on the Wikipedia Reference Desk, the word computing looks like a hyperlink while "medicine" and the others don't. When I click on it, I go through the following sequence of links.

  1. http://search.globofind.com/search.php?q=computing-service
  2. DELETED
  3. http://www.google.com/
  • Many other links on Wikipedia take me to global find in search of something. I have a Windows XP Media Center Edition. I have scanned my computer with the latest version of Norton Anti-virus and found nothing. I have also updated my Windows operating system. I was going to download the Yahoo! toolbar to use its anti-spyware software, but I can't do it.

Can someone help me? When previewing this page, even words that I haven't created links for on the edit page have links after I click "Show preview."Patchouli 22:07, 6 April 2006 (UTC)

ok it looks like you probably have some sort of spyware? first off, i wouldnt bother with the yahoo toolbar, its not going to help anything. go into start->control panel->add/remove programs. look for anything that might be spyware and get rid of it (get rid of viewpoint media player- your spyware is a bit more malicious than that though, so its gotta be some other stuff). download lavasoft adware, install it, get the latest patch inside the program, and run it, delete what it finds. now go download mozilla firefox for your browser... alot of the spyware that targets internet explorer doesnt affect firefox. if you are still having a lot of spyware problems after these 3 steps, there is a simple solution to it all. backup your desktop, my documents, and any other personal data you have, and reinstall windows. modesty 02:50, 7 April 2006 (UTC)
  • I have Ad-aware and have run and deleted everything twice today. Do you think uninstalling Internet Explorer and reinstalling it will help? I can't find IE in the Add/Remove program list.Patchouli 03:10, 7 April 2006 (UTC)
  • I obtained a resolution after calling 1-800-HP-INVENT. Here is what I did.
    1. I opened Internet Explorer.
    2. I clicked on the Tools menu.
    3. I chose Internet Options.
    4. I clicked on the Advanced tab.
    5. I removed the check mark next to “Enable third-party browser extensions (requires restart)" under the Browsing section.
    6. Then I clicked OK, closed the browser, disconnected, and restarted my computer.

This was the panacea to all my browsing and file-downloading issues. Patchouli 05:03, 7 April 2006 (UTC)

It sounds as if this turned off some co-operative adware. Nevertheless, the idea of some unsolicited program in my computer fills me with dread. When I had a hint of this the other day, I immediately disconnected the machine from the internet, formatted the hard disk, reinstalled the system and applications, and then restored my personal data (not programs) from last night's backup. I would recommend you do the same. If you aren't willing to, at least never enter any financial data or important password on this machine, ever again. Notinasnaid 12:16, 7 April 2006 (UTC)
i know how you feel but remember if you browse in fear you are letting the terrorists win!!! modesty 16:23, 7 April 2006 (UTC)

It's 8 times easier to catch something with IE than Firefox. The troubles with my kids went down to nothing when I converted everybody. Apparently, even 'good' sites are being hijacked and filled with exploits. --Zeizmic 15:52, 7 April 2006 (UTC)

  • The Mozilla browser works well only for some time. If you want to keep it permanently, I believe you have to pay $30 for it.
This is simply not true. Both the Mozilla suite and Mozilla Firefox are free --LarryMac 20:40, 10 April 2006 (UTC)


Dear Gentlepeople:


I herewith assert that visiting every site hosted by blogger.com results in an adware and malfuntions on your computers.

Sincerely,

Patchouli 17:55, 9 April 2006 (UTC)

I sincerely doubt you could visit "every site" hosted by blogger.com; that would take quite a long time. Perhaps you mean visiting "any" site, although that would be wrong. My crap little blog is on blogger and I have never been had any adware trouble. --LarryMac 20:40, 10 April 2006 (UTC)

You are correct, I meant "any site." The asseveration arose due to the fact that after I e-mailed Matt Dattilo with my allegation, I received an answer saying,"This is blatantly false. My site is hosted by blogger.com; thus, if it installs spyware, then every site hosted by blogger does."Patchouli 23:09, 10 April 2006 (UTC)

I think you're misunderstanding his reply. — ceejayoz talk 18:06, 13 April 2006 (UTC)

Webmail[edit]

How long has G-mail been an experiment? How long does it take? My university give me this ridiculous 2 Mb inbox limit and delete things without notice if you go over (I've checked, and I can't see how I could possibly over the limit). I'm fed up of it, and since Opera wont let me download IMAP mail (what in the world could make this more difficult than downloading POP email which it allows), I need to find an alternative. Can anyone recommend a service that isn't going to try to charge me to download email or whatever? Another thing that sickens me, is when they say they've "unfortunately" (yeah, right; they "unfortunately" want to extort money out of me) had to reserve the ability to download email or use email clients to paying customers only. Email services should be free, like the sun, the air or the daffodils planted by the council.

Since Google insist on increasing their pledge to users to ludicrously high capacities when they could be opening up 250 Mb accounts to everyone, I pledge to never use their stupid email service as long as I live (or until I forget). --Username132 (talk) 23:50, 6 April 2006 (UTC)

And those "ludicrously high capacity accounts" are open to everyone too. Just find someone with Gmail and ask them to send you an invite. - Mgm|(talk) 10:35, 7 April 2006 (UTC)
Apart from the privacy issues, Gmail sounds like it could fit your needs, check out Yahoo as well though. BTW, someone pays for those daffodils, most likely through taxes, and someone pays for free email, somehow, sometimes by showing you ads, sometimes by using the info in your emails to better show you ads. You might want to think seriously about what the cost of your 'free' email is. For great justice. 00:17, 7 April 2006 (UTC)
Mozilla Thunderbird (website) can download IMAP mail, if that helps. It's completely free, too, and has a ton of other great features. -- Daverocks (talk) 07:27, 7 April 2006 (UTC)
Note that Gmail are playing a bit of a statistical shell game with their claimed capacity. AIUI, they're working on the principle that the vast majority of people aren't going to use anywhere near as much as they've got available, so they can say that the maximum you can have is very high. Couple this with the fact that they are buying more and more disks all the time and you have the basis of the claim. If everybody suddenly "filled" their Gmail mailbox the servers would collapse in a gibbering heap. (Or, more likely, the allowed capacity would drop very quickly until you'd suddenly met it.) --Bth 11:26, 7 April 2006 (UTC)
If you want to keep your school's "free" email (how much of your tuition money is going towards those 2Mbs?), then I'd go with Daverock's solution and get Thunderbird. A mail client will allow you to use your own hard drive as your email's space, and so you could certainly fit 250 MBs or whatever you need. I'm not sure I understand your anger at Gmail, though. It is indeed open to everybody, they just liked the viral marketing strategy they went with. If you'd like an account, just email me or check out any of the Gmail spoolers that are now chock-full of invitations. But like FGJ pointed out, there's no such thing as a free lunch. — Asbestos | Talk (RFC) 13:52, 7 April 2006 (UTC)
AFAIK the spoolers are all now dead. HenryFlower 12:29, 9 April 2006 (UTC)
You can sign up to Gmail using your mobile phone, in quite a few countries now. If you're not able to do that, then I'd be glad to send you an invite if you want one. -- Daverocks (talk) 08:54, 11 April 2006 (UTC)

Relative Velocity[edit]

Given that a person standing still on earth would nonetheless be moving at several thousand kph due to the earth's rotation, and given that this velocity would only be exponentionally increased by the Earth's revolution around the sun, and given the massive speed at which our solar system revolves around the centre of the milky way, and finally, given the milky way's incomprehensible speed in which it drifts away from the centre of the universe, is it possible to estimate the relative speed at which we're actually moving? If so what is it, and how close is it indeed to the speed of light? Loomis51 23:55, 6 April 2006 (UTC)

There is no "center of the universe," although one can sensibly establish a "universal" reference frame based on the frame in which the surface of last scattering of the cosmic microwave background is stationary. It turns out we're moving at about 0.2% of the speed of light, or about 600 kilometers per second [13], relative to that. -- SCZenz 00:01, 7 April 2006 (UTC)
Wow, interesting. I was about to say the question made no sense but your answer's better. Isn't the surface of last scattering expanding, though? So it's not really stationary in any reference frame, just expanding equally in all directions. —Keenan Pepper 00:07, 7 April 2006 (UTC)
The "surface of last scattering" I believe means the surface at which the CMB last scattered (on average) at the time when it scattered. Thus it's a specifically-defined surface in both space and time. Yes, if you trace the CMB into the present day, obviously it's being spread out in all directions, so you can think of the speed I gave as (in rough terms) our speed measured relative to the average "rest frame" of the CMB near the earth (where the expansion of the universe has little effect). All this was determined based on the measured dipole of the CMB, as is indicated in the reference I added above. -- SCZenz 00:10, 7 April 2006 (UTC)
I also read here that the major source of this movement may be the Local Group of galaxies orbiting the Virgo cluster of galaxies. -- SCZenz 00:13, 7 April 2006 (UTC)
Relative velocity is the velocity of the body, this body interacts to another nearby it , as the earth gravity attracts a man, a man drives round the lake by car, the route of the lake is a curve line.
But all of the surveys of motion always observe based on a nearest object , as a man and earth, and the interaction still exist (i.e.: the gravity extraction). Relative velocity can use to compare something which estimates motionless, when you use the term of relative velocity in this case, it is exactly . But if you can win the gravity extraction, it means you leave the earth into univerve, the relative velocity is not the notion which is applied for discussion. Here, the power is enough to win the earth gravity, it already issues the initial velocity , and from here, when you go slowly, it means your initial velocity is reduced some value which is you must register for your itinerary(or you have to use the formula : v(t)= a v(t)+ v ini ) …
Ngocthuan 06 08:59 2006-04-07 (UTC)
I'm not sure I follow your argument; can you clarify? -- SCZenz 20:25, 7 April 2006 (UTC)
If you are an observer standing motionlessly at a corner of the route, you can see a car going with the speed about 50 km/h. It means you and the observed object which are the same condition:- on the earth and very near together.On the earth, it means you rotate around an earth axis (an axis is thru the north & south pole), although you still stand motionlessly , because the earth turn around itself, and the earth goes progessively in the ellipse orbit around the sun, you also have such progessive motion. And a car is same, it rotates around an earth axis.... and goes with the speed 50 km/h.

But when you observe a car, you have to get the origin for the observation, a car run with 50km/h towards only you (still stand motionlessly at this corner), it is the relative velocity.Ngocthuan 06 2006-04-9 T 11:37 UTC

April 7[edit]

Brake Fluid and Clorox[edit]

Hi. i was reading an email when it mentioned something about if you mixed Brake Fluid and Clorox it would make smoke.i was wondering if it would make smoke.if not, is there any other household stuff that when mixed will make smoke?(i like pyrotechnic stuff..)

Thanks, --Shannon 00:46, 8 April 2006 (UTC)

I'm not sure about the brake fluid and bleach, but a Google search will yield some results, such as this. In redox reactions like this, there is an oxidizer and a fuel source to be oxidized. There are too many of these chemicals to list them all, but in the example I gave you above, potassium nitrate is the oxidizer and sugar is the fuel.--Chris 01:12, 7 April 2006 (UTC)

Thanks.do u know where exactly i can get potassium nitrate from?

There is no way to get it easily from household items. It must be purchased specifically. I recommend ScienceLab.com. Please be sure to review the MSDS for potassium nitrate before deciding to work with KNO3. I don't suggest that go ahead with this "experiment" if you do not plan to follow proper safety precautions and have some sense of responsibility. Please follow all directions exactly as they are stated and use your good judgement.--Chris 03:28, 7 April 2006 (UTC)

You might also find it in the local hardware store as 'Stump Remover', where you are supposed to soak the stump in it, let it dry, and then light it. Never worked for me. --Zeizmic 11:56, 7 April 2006 (UTC)

I thought stump remover is straightup black powder, which does have KNO3 in it, plus charcoal and sulfur. --Chris 22:41, 7 April 2006 (UTC)


Hmmm. i will try to find the chemicals and all safety precautions will be observed. Thanks for helpin me find the answer to it =)

--Shannon 00:45, 8 April 2006 (UTC)

Is sleep deprivation good for anything?[edit]

I'm often very tired, and don't have time to get an adequate amount of rest. I'm wondering, is there anything good about sleep deprivation? Flea110 04:22, 7 April 2006 (UTC)

  • Well, according to sleep deprivation, it seems that in amongst all the bad things it can do, low sleep levels might help fight depression... temporarily. Seems like the depression usually comes right back after a normal amount of sleep, though. -- Filliam H Muffman 05:10, 7 April 2006 (UTC)
  • After 36 hours or so you start hallucinating. GangofOne 07:24, 7 April 2006 (UTC)
    • As this PubMed article suggests, sleep deprivation increases serotonergic activity in the brain, which temporarily relieves psychological disorders such as depression. As a person with social anxiety disorder (which is also linked to low serotonin levels), I can confirm that this is true from experience. You should note, however, that you will only get a noticable effect if you have a chemical imbalance in the first place. Oh, and of course eye candy hallucinations are also encountered with sleep deprivation, although I wouldn't describe them as pleasant. --Aramգուտանգ 08:30, 7 April 2006 (UTC)
    • I agree entirely with aram's comments, and for exactly the same reason. I would add, though, that some artists have used the hallucinations associated with sleep deprivation to good purpose - most famously Salvador Dalí. Grutness...wha? 10:37, 7 April 2006 (UTC)
I doubt that. I've been up for 36-48 hours straight quite a few times, and never ever had a hallucination. You can get flashes in front of your eyes, but I wouldn't call that a "hallucination". A migraine can give you that too. --BluePlatypus 15:15, 7 April 2006 (UTC)
Someone here's an outlier then. I've definitely had hallucinations from that sort of length of sleep deprivation (though mine were auditory -- water in pipes seeming like voices, that sort of thing). --Bth 16:02, 7 April 2006 (UTC)
i heard radiohead frontman thom yorke would use sleep derivation sometimes when writing lyrics modesty 16:20, 7 April 2006 (UTC)

Sleep deprivation helps me get work done, as I get too tired to be anxious, and my anxiety contributes significantly to procrastination. moink 21:26, 7 April 2006 (UTC)

Space-Time Curvature under General Relativity[edit]

stereotypical relativity diagram

This is a question about how non-scientific explanations of the Theory of General Relativity are supposed to explain gravitation. Layman explanations of space-time curvature usually have a diagram (apparently always the same one) which shows a two-dimensional surface streched (downwards) into a third dimension at the location of a body having mass. The story goes that a second body going by with no acceleration will follow a curved path because space-time is curved by the first body.

What I don't understand is why this would cause one body to curve towards another rather than away. When I try to figure out what the curved path will actually be (from the diagram), it looks like the it should curve away. Apparently, it is implied that the second body would fall into the 'depression' in the original two-dimensional surface because of.... what? the influence of gravity? It's apparently using gravity to explain gravitation. How is this explanation supposed to work? The Wikipedia article hints it's not a simplistic as the picture, but doesn't seem to go beyond that.

If someone is able to post a complete and thorough reply to this question, please forward it to the Nobel Prize committee. Seriously, though, the curved sheet model just takes advantage of the fact that objects rolling around on a big sheet in a 1 G field happen to move in a way similar to what general relativity predicts for objects moving past planets and the like. It's meant to show you how things move, not why things move. To really understand why things move, you will have to understand nasty things like metric tensors and the Einstein field equations. -- Filliam H Muffman 07:24, 7 April 2006 (UTC)
Well.. I don't quite see why you'd think it would curve away. If you have a downward "dimple" in a tablecloth or similar and roll a ball towards it, moving in a straight line, it will go around the rim in a curved path once it hits the dimple and continue away in a straight line in a different direction, having been deflected somewhat inwards. That analogy is the point of the picture. If the dimple was raised instead of lowered, then it would be deflected in the opposite, outwards, direction. But gravity doesn't act in that direction, which is why you've got a lowered dimple and not a raised one in the picture. --BluePlatypus 07:54, 7 April 2006 (UTC)
The diagram also gives a nice visual analogy for the inverse square law, since the gradiant of the curve is much steeper near the object than far away. But like the others have said, this is a way of visualizing how the objects would move so, not why. — Asbestos | Talk (RFC) 13:36, 7 April 2006 (UTC)
  • In other words, it's just a cool picture? It's describing the exactly the same behaviour as Newtonian gravitation. Peter Grey
  • Pretty much. It's also meant to give an idea that general relativity deals in spacetime curvature, which, among other things, predicts that light is also affected by gravitation. That makes gravitational lensing possible. Newtonian gravity claimed that light doesn't bend because it's massless. -- Filliam H Muffman 03:03, 10 April 2006 (UTC)
One of the byproducts of Special Relativity has been the famous equation, E= mc², that first stated the fact of mass and energy being only two sides of the same coin, instead of what previous physicists have conceived. While Newton had previously thought light to be massless and thus insupsceptible to gravitation, nonetheless certain details within the mathematical framework he had produced for gravity as a force did predict a certain amount of bending occuring when light approaches gravitational bodies (a third less than what Einstein later proposed), which, although he knew was true, was never able to explain away with his theory. The new definition in modern physics, now, for the word massless, also meant something different. It refers only to those particles with no rest mass, but not necessarily no remaining kinetic energy whatsoever. Due to Einstein's equation, as previously indicated, you may say that light does have mass if you wish to, since its energy could be easily converted to mass via the constant of c². However, the energy of the photon is constantly changing during its flight, so the records for mass you will be able to obtain will never be invariant, thus referred to as the relativistic masss. In modern physics, however, it is no longer considered appropriate to define the particle on terms of its relativistic mass for obvious reasons, and thus it suffices to say that light is massless in the fact that it has no rest mass. Nonetheless, as long as the photon still possessed the kinetic energy/relativistic mass necessary for its existence, then it shall be supsceptible to curvatures in space- time like other particles with rest mass. Luthinya 10:21, 10 April 2006 (UTC)
Erm, where have you got that "third less" from? The Newtonian prediction for the deflection of light around a point mass is half the value given by GR. --Bth 10:34, 10 April 2006 (UTC)

Sorry, got my figures wrong. Thanks for correction. Luthinya 10:45, 10 April 2006 (UTC)

This kind of picture is indeed confusing, but there is another reason for it that hasn't been addressed fully above. The key is the mechanism by which "curved spacetime" affects the motion of objects (particles, satellites, light, whatever). General relativity says that an object moving only under the influence of gravity follows a geodesic in spacetime, which is the analogue of a straight line in Euclidean geometry. Since the spacetime itself is curved, these "straight lines" have properties we do not expect, but they are, in a precise sense, the "least curved" lines you can have within curved spacetime.
Roughly speaking (see below), one of the important properties they share with Euclidean straight lines is that they are the shortest distance between two points. This means you can picture a geodesic in the following way. Take a curved surface, such as the dimpled fabric surrounding the ball in the relativity diagram asked about above, and fix two points, one to be the "pitcher" and one to be the "catcher." We then want to draw the geodesic on the curved surface connecting the two points, representing the path of an object from the pitcher to the catcher. We do this by using a rubber band, stretched taut: this automatically follows the shortest path between the points.
Now suppose we look at the result as viewed from above. If there were no curvature, the rubber band would be a straight line between the two points. Since the ball is there, dimpling the surface downward, the rubber band will not take a path that appears straight as viewed from above, since that path will be rather long due to the dimpling. Instead, the rubber band will curve around the ball slightly, to avoid the trip into the depths of the dimple. When seen from above, it appears that the ball is affecting the path of the object with some "force", when in fact the object is trying to follow the best approximation to a "straight line" that it can in the circumstances.
All that is rather hard to say without additional pictures, hope it comes across. Anyway, very little of that is usually included with the usual picture, which is why it is easy to come to very inaccurate conclusions about what the picture is trying to say. If you want a better version of all this, look at Taylor and Wheeler, Spacetime Physics.
Note for experts: in spacetime, with its Lorentz metric, geodesics are actually local maximizers of proper time; but part of the point of the kind of picture we're discussing is to give a Riemannian picture. --Spireguy 20:12, 11 April 2006 (UTC)
Still, for most layemen beginners, it does offer a much more approcheable beginning for the subject, even if much of the important details have been left out. As far as the geodesic problem is concerned, since we as humans possess four dimensions (including Time), and yet space- time may curve in a way that is impossible for us to conceive or imagine- only "talk about", it immediately shows that space- time curves into at least one more dimension than that to which we are accustomed of in our daily life, i.e. the 4D bodies. And just as the 2D figures upon cardboard cannot stand up vertically upon it, since they have no motion or conception of 'depth', we as 4D people cannot cross the barriers of dimension and traverse into the 5th or other higher dimension freely, as we now have the ability to in our 4D world. We therefore have to kind of traverse with the curvatures of the surface of higher- dimensional space- time, which is to us expressed in a 4D fashion like differently laid card boards are to the 2D beings. Thus, for us, the easiest way between two places in space- time may not necessarily be a straight line, but more usually a curved 4D geodesic adapted from the curvatures of space- time from gravity. Luthinya 20:34, 11 April 2006 (UTC)
That's what I'm getting at. Isn't a path curving away from the point mass shorter? What we would need to visualize would be a contraction of space, not a stretching, right? Peter Grey 04:25, 12 April 2006 (UTC)
Bear in mind that we're measuring "shortest" in the coordinate system defined by the grid drawn on the sheet. The deformations of the sheet deform the coordinate system itself -- that's the whole point of the analogy. What looks longer to us from outside the sheet is shorter, when measured in a system where the side of a "square" on the sheet is a constant however stretched it looks to us. --Bth 11:12, 12 April 2006 (UTC)
The shortest path "in the coordinate system" is the straight line. Or is something still missing in the story? Peter Grey 16:13, 12 April 2006 (UTC)
Um, no. In order to walk the "straight line" in which you are depicting, we must abandon the 4th dimensioned (including Time) curvature of the "surface" of the grid (space- time), and seek to traverse into extra dimensions in order to ignore the curved influences of gravitational objects. However as 4D beings this is pratically impossible for us, so instead of this the shortest route for us will have to be the the curved surface of the grid, which at least is 4D and possible to traverse. Therefore, instead of what Newton has previously proposed, the shortest route between two things is not a 'straight line' in the usual sense of the word, but a geodesic varying according to the shape of surrounding space-time influenced by gravitational fields. At least a longer way is shorter than the impossible, so to speak. The thing is that on the diagram you cannot see the grid curving into extra dimensions the way it should, which is what makes the analogy slightly hard to come to mind. Remember the analogy is only a start to understanding; try eventually to draw away from the picture and just let the ideas flow accross your head- aided by some mathematics, you'll find this much easier.

PS May I add that my above language is extremely inaccurate in depiction, especially without the mathematics to compensate for it. Hope it comes through anyway. Luthinya 18:17, 12 April 2006 (UTC)

  • The point I'm trying to underline is that, unless gravity is assumed (as part of the illustration of gravity), then there is no 'up' or 'down', and the diagram should demonstrate the same behaviour whether the deformation is 'down' or 'up'. Peter Grey
I'm afraid I cannot quite catch your point. What exactly do you mean by down or up? The deformation is curved into extra dimensions for which we may only talk of, yet never be able to obtain direct conceptions of for which we will understand properly since, as I said before, we cannot cross the barriers of dimensions. One should also be careful between the shortest path and the easiest path. Traditionally, we tend to think that the shortest path between two things, usually a "straight line", is also the easiest path to traverse between the two objects in question. However, because of this simultaneous involvement in meaning our brain has got accustomed to thinking that the shortest journey must necessarily be the easiest one to achieve, taking seemingly the smallest period of Time (if you can put it like that). Unfortunately, this stops being true as soon as we step out of the world of the Greek Geometres- the flat world of 2Ds where the curvatures made we can entirely ignore, since we are one dimension (in Space) higher. Already in the 3D world we are encountering trouble. When a tourguide shows you the fastest way to cross a mountain, he shows you the curved path just by the foot of the mountain and fitted to its topological curvatures. However, who would not agree that the shortest way is actually to tunnel through the mountain centre itself, and come upon the other side? True, this may be the shortest way, but it is by no means the easiest. Far easier it is to adapt to the geodesic of the landscape than to delve in it.

Space- time itself possesses more dimensions than our race, so delving becomes completely impossible. All we can do now is follow, once again, the geodesics of the landscape, and trust them to be our easiest way. (or trust maths- whichever)There will be no talk of picking or choosing either- all objects follow intuitively the easiest way to traverse between two points. When there is a stone that curves a rubber sheet downwards the ant naturally walk as close to the stone as possible in getting its way round to the other side, not even waste time climbing or delving into the stone. The same it is for us- we naturally follow the curvatures already made in the fabric of space- time. When a gigantic gravitational body curves space-time into extra dimensions unreacheable, the easiest way to cross to the other side is to the follow the geodesics and walk as close to the body as possible, giving the effect of being "gravitated towards it", rather than away from it where the journey will naturally be harder. Luthinya 09:55, 14 April 2006 (UTC)

TO CLEAR UP THIS DISCUSSION, WHICH SEEMED TO HAVE CREATED A GOOD DEAL OF GENERAL INTEREST, I SHALL REMOVE THIS QUERY FURTHER NOW TO THE BOTTOM OF THIS LIST, AT APRIL 14TH. THANK YOU FOR YOUR UNDERSTANDING. Luthinya 09:58, 14 April 2006 (UTC)

Sports Science[edit]

How can the diet of a body builder be compared to the diet of a jockey?

In many ways. You could compare the number of calories, or the proportion of carbohydrates, or even the sheer weight of the two diets. Grutness...wha? 10:35, 7 April 2006 (UTC)

It's probably a polite fiction that people can significantly bulk up without an Anabolic steroid. Just compare the body builders of yesteryear with the Rambo's of today. --Zeizmic 14:52, 7 April 2006 (UTC)

It's definitely possible. Depends what your goal for bulk is, but with enough protein and exercise, one can add major muscle mass without resorting to drugs. You may not end up looking like the hulk, but rambo is in reach, given the right genes. Night Gyr 17:35, 7 April 2006 (UTC)

Time dilation[edit]

What is the easiest way to understand length contraction and time dilation?

Here on Wikipedia, a good starting point might be our Introduction to Special Relativity page, which takes a fairly unusual but (IMO) particularly clear geometrical approach. For more details, try our articles on length contraction and time dilation. Elsewhere online, sites like this and this take the more common playing-ping-pong-on-a-train approach. Do come back here if you have anything you want cleared up. --Bth 11:20, 7 April 2006 (UTC)

Create a super computer by many used computers[edit]

I hear that we can create a super computer by many used computer, it means that If I have about 10 pcs of Pentium III Pc, I can create one super computer. The Operating System now is open source.User: Ngocthuan 06 2006-04-7 19:52 UTC

If you had looked at the supercomputer article, you could have probably seen Beowulf (computing), which is the standard model for making a supercomputer cluster. The links and external links in that article will probably tell you most of what you're looking for. — Asbestos | Talk (RFC) 13:19, 7 April 2006 (UTC)

Logical way to finish this Sudoku?[edit]

I got annoyed with the Sudoku today because it took me more than 2-3 stops on the T to solve, so now I've decided that it was a bad puzzle (obviously). I solved the puzzle by supposing one box was one number, working through it all and seeing that it didn't lead to any contradictions. My question is: Was there a logical way to finish this sudoku, without starting with "Suppose this box is a ...", and then showing presence or absence of a contradiction? I realize that that is an ok way of finishing a tough sudoku, but I far prefer it when they can be solved more elegantly:

7 2| 6 | 98
5  |928| 71
98 |74 |  2
-----------
6 8|29 | 17
273|156|849
19 | 87|2 6
-----------
3  |872|964
427|639|185
869| 1 |723

Thanks! — Asbestos | Talk (RFC) 13:16, 7 April 2006 (UTC)

Probably not, the puzzle looks like it's been designed with the "pick one of two choices and see if it leads to a contradiction" method in mind. Parts of it can be solved independently, though: for eample, one of the two possible choices for filling the central square leads to a fairly obvious contradiction in the central columns. —Ilmari Karonen (talk) 17:12, 7 April 2006 (UTC)
I'd agree, I can't see a way to do it that doesn't rely on guesswork^W proof by contradiction. As such, it doesn't count as a well-formed sudoku to my way of thinking. --Bth 17:18, 7 April 2006 (UTC)
All solutions depend on proving-by-contradiction. Some of the problems just have more obvious contradictions, making it easier to find the correct one. It's an NP-complete problem, so one solution isn't really much more elgant than the other since they all more or less imply testing all the possibilities. So the perceived elegance is more about whether you can solve it within your mental 'search depth', or whether you have to resort to writing the numbers down. --BluePlatypus 18:23, 7 April 2006 (UTC)
I see what you mean, but solving using the various other "standard" techniques (listed at length in our sudoku article) doesn't feel like guesswork/proof-by-contradiction in the way that having to employ the "what-if" method does. I've never seen a sudoku before that had to be solved by what-if. (OTOH, I've often solved them by that and then used my knowledge of the solution to see what I'd missed in my application of the other techniques.) --Bth 18:54, 7 April 2006 (UTC)
Well, yes and no. Personally I feel that a sudoku should be solvable by deduction in that you should logically be able to deduce simply by examining the puzzle what particular number will go into a space. If you are left with a situation where the only way of finding out is to plug in numbers and see whether the correct solution can be reached you've gone beyond deductive reasoning and into inductive reasoning - a different matter entirely, my dear Watson. Grutness...wha? 03:41, 8 April 2006 (UTC)
Cheating, and using http://sudoku.sourceforge.net/, and adding in all of your available numbers. There is no solution. Sorry! Kilo-Lima|(talk) 16:54, 10 April 2006 (UTC)
There is indeed a solution according to that site, although it requires a guess. Are you sure you filled it in correctly? --Pidgeot (t) (c) (e) 20:25, 10 April 2006 (UTC)

Desktop & Laptop screen placement[edit]

1)In a desktop, the monitor is more or less perpendicular to the desk, and we view that monitor with 3 feet distance. If we use a laptop or a tablet pc whose screen is placed at 45 degrees to the desk/lap, should the same distance of 3 feet be maintained? Or simply, if viewing angle changes, should there be a difference in viewing distance?

2)What is the reccommended viewing distance and reccommended angle for placing laptop screens?

When we place the screen on the laps in a slate tablet PC, the viewing distance is 1 to 1.5 feet. Does that say that viewing distance is related to angle of viewing?

Laptops and tablets are not particularly ergonomic. Get an external keyboard and jack your laptop up on some phone directories when you are using it as a desktop replacement. For great justice. 18:38, 7 April 2006 (UTC)
You can get stands that hold the laptop screen vertically at eye level (the ones we use do so by having a 30° tray to put the laptop base-part on, with the hinge furthest away from you) and plug in an external keyboard and mouse. Ojw 20:36, 8 April 2006 (UTC)
Your screen is probably not at a 45 degree angle; many laptops are barely even capable of bending that far. Night Gyr 06:29, 9 April 2006 (UTC)

Can Envelopes Be Composted?[edit]

Paper can be recycled or composted but envelopes cannot be recycled due to the glue. Can envelopes (without plastic windows) be composted? --Username132 (talk) 15:16, 7 April 2006 (UTC)

Theoretically, most things can be, but consult your local recycling company for their facilities / policies on this. For great justice. 18:36, 7 April 2006 (UTC)
I'm sorry - you said composted, not recycled! They will certainly break down if you put them in a composter - the question is, not knowing exactly what chemicals are in it, you might not want to use the compost on vegetables etc you want to eat - otherwise, go for it. For great justice. 22:24, 7 April 2006 (UTC)
The recommended constituents of compost are: 1) vegetable waste (and some miscellaneous kitchen waste like tea bags, eggshells, etc), 2) lawn trimmings or leaves, and 3) shredded newspaper, straw, or wood chips. Bleached paper (normal office paper, including envelopes), cardboard, other paper, cooked food, animal-based waste (except eggshells), fats, etc while capable of decomposition, are NOT recommended for composting.
In the case of office paper (as per your question), it is both the chemicals in the paper and the density of the paper. 'Perfect' compost is alternating layers of dense vegetable matter (kitchen scraps), dry vegetable matter (lawn trimmings or leaves), and cellulose (straw, wood chips or SHREDDED newspaper), not necessarily in that order but definitely including all three. The combination of the three types of elements is ideal for the cultivation of all the different types of organisms that turn waste into soil. If you don't follow the 'formula', your compost will still decompose, but it will be slower, smellier, and grosser.
Newspaper is included for two reasons; one is that it aerates the pile, and it is actually nutritious to worms. White paper is like refined sugar, it has no nutrient value, so worms wouldn't eat it. It's also dense and soaked with chemicals, which would inhibit the movement of the worms and maybe poison them. IF the paper decomposed, it would be a slow process facilitated by bacteria which would be acting on the organic drippings from other parts of the compost that would 'soak in' to the paper. It's waaaaay better to leave it out, most compost experts say leave it out. Recycle your office paper through your city's recycling programme, or send it to the dump to follow its own decompositional path, away from your compost pile.--Anchoress 00:55, 11 April 2006 (UTC)
Thank you - compost without the envelopes it is! :) --Username132 (talk) 04:06, 11 April 2006 (UTC)
No problem. I also forgot to mention that - as far as animal waste is concerned - manure is fine, but not dog, cat or human feces. Also some documentation says cardboard is OK, I think the main thing is unbleached, unpressed paper, and ideally it should be shredded. In my jurisdiction they say only newspaper, no other kinds of paper.--Anchoress 04:34, 11 April 2006 (UTC)

Dr. Keith Black neurosurgeon[edit]

Why is there no information on Kieth Black M.D. on wikipedia ?

Because no one has added anything about him yet. I didn't know who you were talking about so I looked him up. He doesn't seem terribly notable to me, but if you feel like adding information about him, go ahead. Be Bold. Chapuisat 16:55, 7 April 2006 (UTC)
He seems sufficiently notable to me to warrant an article (and to displace the drag-racing Keith Black to a disambig link), so I've created a stub for him based on a quick Google search; I'd strongly encourage the questioner to add some info if they have any. More generally, to expand on Chapuisat's point, Wikipedia has gaps and omissions because it's entirely the result of volunteer contributions and constitutes a permanent work in progress. --Bth 17:00, 7 April 2006 (UTC)
  • If one added every living and dead physician, lawyer, and dentist, then we would have maybe over 10,000,000 articles on these folks alone. Unless that person made a breakthrough and accomplished something meaningful, I don't think such articles would be needed.Patchouli 23:54, 7 April 2006 (UTC)

Linux[edit]

From a Linux tutorial; "Most modern Linux distributions encourage a practice in which each user has a specific directory for the programs he/she personally uses. This directory is called bin and is a subdirectory of your home directory."

Would it not be inefficient for many users to have different copies of the same program? --Username132 (talk) 16:42, 7 April 2006 (UTC)

Well, if it's a big multi-user system, each user probably has a disk quota that they can use to store whatever they want. If the programs they want to run aren't available in /usr/bin or /usr/local/bin or whatever, they can put them in /home/whoever/bin. —Keenan Pepper 17:07, 7 April 2006 (UTC)
And the particular situation of everyone having a local copy of SuperWhizzyUtilityX shouldn't arise if the sysadmin's on the ball. They should be putting anything that several users want into /usr/bin and such places. (Incidentally, if you want to see where the shell searches for executables when interpreting command lines, type "echo $PATH" to see the (colon-separated) list stored in the PATH environment variable.) --Bth 17:15, 7 April 2006 (UTC)
It may be a tad inefficient, but it's a lot better than sharing the same installation - what if someone deletes the program? Bth's point is also a good one - commonly used applications get installed into a shared directory they can access but not modify.

Gold in sea water[edit]

I have read somewhere that there is approximately 9 tonnes of gold per km cubed in sea water. --

-Is this true for all seas (apart from where there is large amounts of fresh meltwater)?

-Is the same true for fresh water and what is the amounts?

-Is the gold not worth anything (like industrial diamonds)?

-Is there an efficient/cost effective way of extracting this gold, taking into account; positioning (what sea/ocean), labour, building/machienry etc.

-If you discover anything "good" please don't make it "exceptionately clear" to anyone else and put it on the website. I cant force you to but pretty please do.


Im slightly mad but if it wil work i will be slightly rich....Yipee!!!


                I think im ment to do this: --William Dady 16:58, 7 April 2006 (UTC)
The presence of trace amounts of gold and other precious metals in seawater is not a secret, and it is not economically feasible to extract it because the concentration is so low. 9 tonnes may seem like a lot, but a cubic kilometer is a ridiculous amount of water. See [14] and Fritz Haber, a brilliant chemist who tried and failed. —Keenan Pepper 17:12, 7 April 2006 (UTC)
To put it into perspective, a cubic km of water weighs about a trillion (1,000,000,000,000) kg, or a billion metric tonnes. So you got a concentration in the 9 parts per billion (mass) (by your numbers).
Actually, according to this article [[15]] ,the highest concentration found was 0,05 ppb and average was 0,013 ppb. To put it into a more "real-world" size perspectve: One olympic pool of "good" sea water (3 million liters) should give you 150 milligrams of gold, worth US$ 3. --Rodrigo Novaes 15:42, 14 April 2006 (UTC)


The 1st billion tonnes is the hardest. --GraemeL (talk) 23:39, 7 April 2006 (UTC)
Thanks for your query. We figured it out but sorry we're not sharing. alteripse 14:59, 8 April 2006 (UTC)
Finally, there are two metals that might one day be economically viable to extract from seawater - uranium and vanadium. See this abstract. Arthur C. Clarke wrote a short story about the idea decades ago. --Robert Merkel 08:12, 9 April 2006 (UTC)

Centrifugal Force[edit]

If a space station were to have a ring with people inside and it was spinning fast enough then it should create artificial gravity. So my question is if a person inside this ring where to jum up would he or she be pulled down to the spot where the jumped up from? Patrick Kreidt

Essentially, yes. You should draw a force diagram of the situation you are talking about. I think you are interested in whether the ring would 'spin' under the person while they were in the air? Sketching out a diagram will show that there are no forces that will do this in the example you mention. For great justice. 18:34, 7 April 2006 (UTC)
I don't think so. Maybe I have not thought this completely out, but here is how I see it. At the time a person jumps 'up' (and 'up' is defined as perpendicular to the surface) a person will be moving forward at a certain speed. Ignoring air friction the person will continue to move forward at the same speed the floor is moveing forward. Since the floor moves in a circle and the person does not, for the person to come down in the same place would require the floor to travel a longer distance in the same time the person requires to land. From this I conclude the person will land in a spot a little ahead of the take-off point.
Why doesn't the person move in a circle? As the ring spins, it emparts momentum to the person at an angle tengental to circle, that means they spin, with the ring, and are pushed away from the center of rotation. If the person jumps towards the center of the ring, they already have momentum emparted by the ring that will carry them 'forward' at the same rate that the ring is spinning. For great justice. 20:49, 7 April 2006 (UTC)

OK - so take a look at the diagradm - the black arrow shows the force vector of the spinning ring. The red arrow the direction of spin, and the green arrow the arc of the jumping man. Because he has the same forward motion as the ring, the arc he describes, even if he jumps 'up', will put him back where he began. For great justice. 21:06, 7 April 2006 (UTC)

That's roughly true, but remember that the ring moves in a circle, whereas the person's initial velocity (aside from the "jumping speed") is tangential to the circle at the time of the jump. I think you land in roughly the same place, for small jumps, but getting an exact answer requires actually calculating it out. -- SCZenz 21:21, 7 April 2006 (UTC)
Er, I don't think it quite works like that. You have to remember that there's no force 'down' (outward) on the jumping man, just whatever residual momentum he carried when he left the ring.
Picture the following situation. The ring sits in the plane of this webpage, like this: → O
The ring rotates counterclockwise. The top of the ring is moving left (←) and the bottom is moving right (→).
Our hypothetical spaceman is standing on the inner surface of the rotating ring. Assume that we conduct our experiment just as he reaches the bottom of the circle. He, and the ring, are both going to be moving to the right (→) with equal speed.
The spaceman jumps. He retains the original horizontal component of his speed → and adds a modest upward component (↑), assuming he pushes off normal to the ring surface. The path he follows will then be straight along the vector sum of those two components, taking him diagonally up and to the right on our diagram until he smacks into the wall again (er, lands).
So, what happens? Let's follow the spot of ring from which our spaceman started. Its horizontal velocity will be
vhoriz(t) = vmax·cos(ω·t)
where positive velocity is to the right. In other words, its velocity is at a maximum at the bottom of the circle, and decreases as the centrifuge turns.
Our spaceman, on the other hand, retains all of his initial horizontal velocity, so he lands ahead of his starting point. TenOfAllTrades(talk) 21:21, 7 April 2006 (UTC)
Hmmm...looking at that explanation, I think I can cut it down a bit by looking at the problem in a slightly different way.
  1. The launch point on the ring travels at constant speed along a curved path.
  2. The astronaut travels at a constant speed greater than the speed of the ring surface (remember the vector addition of his jump velocity to the ring's velocity) along a straight path.
  3. The two paths intersect at some point after the jump.
  4. The astronaut gets there first — he followed a straight path at higher speed. Therefore, the astronaut will land at a point on the ring ahead of his departure point. TenOfAllTrades(talk) 21:26, 7 April 2006 (UTC)
So, my diagram is wrong, because the spaceman describes a straight line, not a parabola? For great justice. 21:30, 7 April 2006 (UTC)
Huh. Thanks, that'll teach people to trust anything that they read on the internet! So, why does this not work on earth, which looks like the opposite case? For great justice. 21:27, 7 April 2006 (UTC)
I think it does work on earth, but the difference is so small it can be ignored. Keep in mind, on Earth you will only be jumping maybe 3 feet, on a ball with a 4000 mile radius. I will try to explain, though. Remember that circumferance increases in direct proportion to the radius. This means the arc of a circle with 4000mi radius will be slighty shorter than the same number of degrees of arc of a circle with 4000mi+3feet radius. This means your jumper will have to move a longer distance in the same time the earth does to traverse the same arc.
How about this version? For earth, actually I think the difference is that you do describe an arc, not a line, because gravity is continually acting on you - no? For great justice. 21:34, 7 April 2006 (UTC)
The Earth case is quite a bit more complicated due to gravity, yes. Where you land (ahead or behind your starting point) depends on the size of the centrifuge and speed of rotation (note that it has to be fast enough that you don't fall off when you go over the top....) as well as the impulse you give yourself during your jump. In the special case where you jump while the centrifuge is at the bottom center (as described in my first though experiment above), you'll land ahead of your jumping off point—it comes down to the person maintaining a constant horizontal velocity while the jumping off point is losing the horizontal component of its velocity. I'm too tired to work through the consequences for anywhere else on the centrifuge right now. TenOfAllTrades(talk) 03:41, 8 April 2006 (UTC)
The easiest way to figure out the direction of these effects, and their approximate magnitude, is to pretend the Earth (or other spinning body) is actually at rest, but apply the Coriolis force. --Trovatore 16:40, 8 April 2006 (UTC)
1) There is no such thing as actually at rest.
2) The very fact that you may apply the Coriolis force to a body already implies that it's spinning.
The field of 'artifical gravitation' generated by the spinning ring must be understood as a fairly universal field of 'gravitation', at least certainly one in which the Equivalence Principle may apply, in making this question at all possible. Yet when the astronaut jumps vertically from the ring's frame of reference, the artifical gravitational field acting upon him draws slightly weaker effects due to the longer distance, but the field itself still remains fairly universal for our purposes. However, when the astronaut is jumping up, though he shall still ultimately be drawn to the ring, during his time of suspension he is no longer travelling in the direction of its spin or with its velocity. As we have settled that the field shall be considered universal for our purposes, then it follows that he shall not be drawn to the particular place from which he jumped more than any other. Thus, following the above discussion, it appears plausible that the astronaut shall land in a slightly different place from where he jumped, the exact position determined by other factors and certainly noticeable if the ring was spinning fast enough- and he had not jumped too far away!
Galileo himself actually suffered the same kind of inaccuracy due to the spinning of the Earth from his famous experiment on the Tower of Pisa, however in that case the indescrepancy was too small to mar the ultimate judgment of the experiment. Luthinya 10:38, 9 April 2006 (UTC)

Chemical structure formula in Word?[edit]

Does anyone know of any (free) application able to draw chemical structure formulas and save them into the WMF or EMF format, so that they can be inserted in for instance Microsoft Word? --Andreas Rejbrand 18:39, 7 April 2006 (UTC)

You might try ChemSketch.[16] There's a free version, but I'm not sure what file formats it can save in. ChemDraw can save in those file formats, but there aren't any free versions, as far as I know. --Ed (Edgar181) 18:47, 7 April 2006 (UTC)
Thanks; I'll have a look at it. --Andreas Rejbrand 18:49, 7 April 2006 (UTC)
Now I've tested it, and it really looks great. Thank you for informing me, Edgar181. --Andreas Rejbrand 19:12, 7 April 2006 (UTC)

Total human decomposition in Canada[edit]

A tall order, I know, but I was wondering how long it would take a human body to totally decompose in a four-season (with a "real" winter, which is to say at least one or two months below zero degrees Celsius) environment.

I've read up on decomposition and eco-cemeteries (the latter being the reason I'm interested in the question), but neither go into enough detail to really tell me how long, pillar to post, it takes before a body is entirely gone. Skeleton included.

I'm aware that there are factors like ground moisture, limestone, etc. involved, but a ballpark-by-decade would be great. 10 years? 20? 60? Thanks! --MattShepherd 20:13, 7 April 2006 (UTC)

I'm no expert but i know the location where you bury the body really matters, they've found human skeletons and even bodies still fully formed (in admitedly extreme conditions) that are hundreds of thousand of years old.

The tricky part is the skeleton, which generally requires salt-water or something rather caustic to break it down. The rest is broken down fairly easily, unless there is some extreme condition in which microbes can not exist. StuRat 07:57, 8 April 2006 (UTC)
  • Skeletons can remain for ages in good conditions. Your best bet would be to contact the Body Farm in Tenessee, but you'd better explain why you want to know to them... - Mgm|(talk) 19:40, 8 April 2006 (UTC)

Even cremation does not destroy the skeleton completely. See the article for details. --Rodrigo Novaes 13:19, 14 April 2006 (UTC)

what if..[edit]

if every single human being on the face of the earth decided to jump 1 foot to the right, at the exact same time would it be enough force in one direction to shift the earths orbit? tilt? tidal forces? register on a ricter scale?21:13, 7 April 2006 (UTC)

The Straight Dope answers the question for the specific case of China - seems like not much would happen. [17]. Answerbag has another demonstration of why this is bogus [18]. For great justice. 21:17, 7 April 2006 (UTC)
nah thers no way, but i mean if you do think about it, every particle in your body is exerting gravity on everything... all the time modesty 03:58, 8 April 2006 (UTC)
I think this is an example of the falacy of equivalence of large numbers. The earth is really big, and the number of people on it times their weight is really big. Therefore they are equivalent, and one will automatically effect the other. For great justice. 22:19, 8 April 2006 (UTC)

Why does DNA only replicate in the 5' - 3' direction and not vice versa?[edit]

I know this is kind of a homework question and you guys don't like that which is fair enough, but i'm revising for my degree and really have no idea why. I am generally quite interested anyway. Cheers, Mark west 80.42.104.21 22:23, 7 April 2006 (UTC)

I believe it is because the enzyme that catalyses the the replication process can only grip on the "5" end of a strain. Since it can't start at the "3" end, 3-5 replication does not happen. Note that this is from my sketchy memory of biochemistry 5 years ago. SanderJK 23:27, 7 April 2006 (UTC)
WRT homework questions, there's no problem with asking specific factual questions (like yours seems to be, though it's an area I know nothing about). What we object to is when people post an essay topic, or a physics homework problem, or the like, and expect us to do the task for them in its entirety. --Robert Merkel 00:28, 8 April 2006 (UTC)

The reason that synthesis can only occur in the 5'-3' direction is based on the reason these names exist in the first place. If you are an applicant for a degree in molecular biology or something similar, then you know that these names, 5' and 3', refer to the carbon positions in the deoxyribose backbone. Both the 3' and 5' carbons have hydroxyl (alcohol) groups attached, however, wheras the 3' carbon is part of the ring, the 5' carbon is sticking out (read: much more reactive). Therefore, when DNA is split into monomers, deoxyribose molecules with purine or pyrmidine residues, the 5' carbon loses a bond, whereas the 3' carbon is not directly affected (instead the oxygen in the hydroxl loses a bond). Now consider this, since the residue separating the 5' end of one monomer and the 3' end of the next is a phosphate, the electron in the bond between a phosphate (which is completely resonance stabilized) and the sugar monomer is much more likely to go to the phosphate. Thus the positive charge can stick on the 3' oxygen (unlikely) or the 5' carbon (very likely). So wiht all this information, we can explode a diagram of DNA: you have a sugar monomer with a + charge at the exposed 5' carbon and a stable 3' carbon with full bonds and a stable hydroxl; and a phosphate with a - charge. Thus the most likely eventuality is a deoxyribose monomer with a phosphate attached at the 5' carbon. Since the active sight on the polymerase protein is reactive to the hydroxl side, it sits on the 3' end of the DNA chain and waits fot another monomer to come by, then attaches it via the floater's 5' end. Look at this attachment form far a way, and the chain appears to be growing from the 5' to the 3' direction.Tuckerekcut 16:23, 9 April 2006 (UTC)

Awesome answer, that helped a lot, thanks Tuckerekcut.

What is the alloy grade of cast steel which used for cylinder head?[edit]

In low speed diesel engine, the cylinder head is Manufactured from cast steel. Please, I need to know the alloy grade of cast steel and the folloing properties: 1- denisty 2- specific heat 3- thermal conductivity

thank you

That's a toughie. You might have to ask a manufacturer of low-speed diesels like MTU to find out - or get a hold of a sample and take it off to the metallurgy lab. If you're interested because you want to set up in competion to them, the latter might be your only option. --Robert Merkel 00:35, 8 April 2006 (UTC)

April 8[edit]

Electrical Storms[edit]

Why do electrical storms only seem to occur in a rainstorm, but never in a snowstorm? Loomis51 00:19, 8 April 2006 (UTC)

It's possible to see lightning in a snowstorm. I saw it several times in New Hampshire. Brian G. Crawford 01:10, 8 April 2006 (UTC)

See the environmental lapse rate page. A thunderstorm derives some of its energy from air rising in an unstable atmosphere, and moisture condensing as it cools. Warmer air on the bottom can hold more moisture and is more unstable than cooler air. EricR 01:55, 8 April 2006 (UTC)

Lightning in a snowstorm is referred to as thundersnow, and we had it here this winter. Night Gyr 03:27, 8 April 2006 (UTC)

It depends a lot on other factors, probably - such as the location of the storm, wind currents, etc etc etc. Here in southern New Zealand, for instance, thunderstorms are almost always accompanied by hail rather than rain. And yes, lightning quite often strikes over the sea (where I live I've got a great view over the Pacific), with no obviously spectacular results. Grutness...wha? 04:37, 8 April 2006 (UTC)

Also, does lightning strike in the sea, and if so does anything special happen compared to striking land? --Username132 (talk) 01:28, 8 April 2006 (UTC)

  • Yes, lightning does strike at sea, and many boats are damaged in this way ([[19]]).

At land, unless the lightning strikes at you or very close, you're in no trouble. In the sea, because of salt, electricity is conducted (see Electrical conduction). You will get a severe shock from a relatively distant ray if you are taking a bath or even standing at a wet part of the beach.

Figures are that 70-90% of people will survive a lightning, but even a 10% chance of death doesn't look very appealing to me. --Rodrigo Novaes 13:38, 14 April 2006 (UTC)

Oxidizing Heavy Metals Salts[edit]

I would like to know in details about the oxidizing heavy-metal salts as this relates to corrosion of copper and copper alloys. Copper alloys resist many saline solutions, alkaline solutions, and organic chemicals. However, copper is susceptible to more rapid attack in oxidizing acids, oxidizing heavy-metal salts, sulfur, ammonia (NH3), and some sulfur and NH3 compounds.

We have a corrosion problem in one of our gas engines of Caterpillar and the service engineer identified the occurance of oxidizing heavy-metal salts on a engine part made of copper alloy.

I would appreciate your helping me out of this situation by providing details obout oxidizing heavy-metal salts.


Thanks & Regards,

Ahmed Mohiuddin Caltex Oil (Pakistan) Limited A chevron Company

The obvious answer is to replace the copper with something less reactive, like gold or platinum. Another option would be to supply a "sacrificial rod", say made out of aluminum or magnesium, which would react with the heavy metal salts in place of the copper. The rod would need to be replaced as it corrodes, of course. One option might be to place the rod in the oil reservoir. Hopefully, the oil will carry the salts to the rod before they can attack the copper. The rod could be attached to the oil cap, but must be long enough to extend down into the oil in all conditions. Water heaters often use a sacrificial rod. StuRat 07:28, 8 April 2006 (UTC)
You may be looking for the article on sacrificial anode. TenOfAllTrades(talk) 14:28, 8 April 2006 (UTC)

Adobe Photoshop Album Starter Edition 3.0[edit]

okay....im really starting to get mad at my Adobe Photoshop Album Starter Edition 3.0 because every time i go to a website any pictures that are on the site are automatically saved to it. Does anyone know how to stop it from doing this?I dont even have to look at the picture specifically...it just automatically saves it....really annoying.


Thanks for any help, Shannon 03:15, 8 April 2006 (UTC)

This is NOT a science question. Ohanian 04:46, 8 April 2006 (UTC)

No, but it's a computer question. I don't know the software, but look for a preferences tab on programs icon bar, failing that, what do you use it for? Why not uninstal it and use a free image editor like The Gimp? For great justice. 06:49, 8 April 2006 (UTC)
Ohanian, please note this text from the main ref desk page, referring to the Science desk: "To ask questions about science, medicine, computing, and technology" --LarryMac 20:17, 10 April 2006 (UTC)


okay ill do that thanks. Shannon 01:14, 9 April 2006 (UTC)

What is hafnium's cosmic history?[edit]

What is hafnium's cosmic history? I've looked everywhere I think I could find that information, but I can't seem to get any information that I need. Could you help me find the information I need, please?

What do you mean by "cosmic history"? The only thing I can think of is how it was originally formed, which it shares in common with all the heavier elements, so I don't understand why hafnium has been singled out. You may want to look at our article on nucleosynthesis for more on that. --Bth 07:12, 8 April 2006 (UTC)

Ear ringing[edit]

My ears ring when I have earplugs in, I read in the wikipedia article that theres no cure for it, but I was wondering if this was normal, and if there was anything I could do to make them stop ringing, thanks.

Flents
  • I have used Flents foam ear plugs which I have learned reduce ringing more than any other type of earplug. However, after wearing earplugs for over six hours every day for some time, I noticed that the ringing sound stayed even after I took the earplugs out of my ears; this is tinnitus. I my case, it ceased after I stopped putting earplugs in my ears for a month. Try to use the earplugs only if it is necessary.Patchouli 09:44, 8 April 2006 (UTC)

The ringing you are experiencing is indeed called [tinnitus], but it is not caused by the earplugs themselves. Most likely your tinnitus is constant throughout the day, however you dont notice it because of the ubiquitous background noise of daily life. Even in the dead of night, the hum of environmental control systems and various electronics in your environment distracts your attention from the ringing sound. However, when you put in earplugs, these sounds are muffled, and the ringing sound, which has been present as a tiny, unwavering signal from your ears to your brain, becomes relatively large compared to the background noise, and you notice it. Unfortunately, tinnitus tends to get worse as we age, mostly from incremental damage to our sensitive ears. Ringing due to acute damage may fade away after a few hours or days, but the underlying chronic tinnitus described here tends to be permanent. Tuckerekcut 15:54, 9 April 2006 (UTC)

Not enough sleep...[edit]

having "black lower eyelids" (i don't know its real name) has always been frustrating to many people. i always wonder why they appear when we don't get enough sleep, and perhaps there might be some other reasons?... i would be more than grateful if you could just stop by and answer this question for me. Thx! --219.77.165.58 11:18, 8 April 2006 (UTC)

The skin around the eye (especially directly under it) is extremely thin and has a lot of blood vessels in it. While you are awake, your eyes stay open most of the time and you get a buildup of gunk (wax, dust, salt, etc...) in your eye. Tears help keep it clean, but they work best at night with your eyes closed and with plenty of REM. That buildup does two things - pushes blood vessels closer to the surface of the skin and blocks flow, making the vessels expand slightly. The more visible vessels are what you are seeing when you see shadows (and puffiness) under you eyes. --Kainaw (talk) 16:49, 8 April 2006 (UTC)
By the way, the more common term for this is "bags under the eyes". — Asbestos | Talk (RFC) 14:28, 10 April 2006 (UTC)

genius v.s. lunatics[edit]

many great mathematitians and well known scientist have the tendency of being nuts, but why is that? Thx :)

A simple answer to your question is that people who are capable of making brilliant new developments (in any field whether it's math, science, philosophy, etc.) tend to be people that think differently than others, that look at problems in a new way, or don't simply accept the traditional point of view. Society tends to think of people with that kind of outlook as nuts (or at least "eccentric" in polite company). --Ed (Edgar181) 11:42, 8 April 2006 (UTC)
I'm also fairly sure that the genius/lunatic thing is incorrect. In my recollection, there is no correlation between true mental illness and intelligence, but the cases in which they do correlate are generally so interesting and noteworthy that we end up letting them dominate our perception of it. --Fastfission 12:07, 8 April 2006 (UTC)
I'd agree with both statements, and would like to add the fact that from my runins with various scientists i would say that many fields tend to attract certain kind of people, and that the studying of some fields can really change your view of the world. Combined with a certain social ineptness that does seem more common among researchers then in most circles, and the relatively often portrail of autistic savant in popular media, and the fact that abnormal people (including scientists) will get more media attention in general, it is easy to understand how such a picture of scientists would become widespread. Most of all, they are just people, perhaps with a little workaholic nature engrained. SanderJK 13:00, 8 April 2006 (UTC)

My cynical hemisphere will bet it's 99% a matter of noticing. Ordinary person has mental illness-- no news. "Brilliant" mathematician (is there any other kind?) or scientist has mental illness, and everybody can feel reassured that they are better off and savor the irony of the smarter guy's misfortune. Eccentricity and poor social skills are usually distinguishable from major mental illness. (what is the dsm-iv for "nuts," anyway?) alteripse 14:56, 8 April 2006 (UTC)

In the case of a "genius", poor social skills and a constant preoccupation are what others call "mental illness". As an example, Einstein has terrible people skills. After his wife died, he became a shut-in. When in public, he either did his obligatory presentation or stayed away from the crowd, preoccupied with other things. Over and over, the genius form of antisocial behaviour has been explained as a disdain for the stupidity of humans in general. Einstein's quote, if I remember correctly, is that "Only two things are infinite, space and human stupidity. I'm not sure about the former." As for the preoccupation, they are working on problems that they find much more interesting than what to have for dinner or which politician do we want to raise our taxes next year. All in all, I see it as an adult trying to fit in with a class of preschool children. The children aren't really stupid, they are normal. The adult isn't mentally ill either. They are just focused on different things. --Kainaw (talk) 16:44, 8 April 2006 (UTC)
OTOH, a large part of Einsteins 'genius' status is the fact that he fit so well into the stereotype. I'd say he was a large part of defining it. By comparison, Bertrand Russell for instance, shared a similarily negative view of humanity but was quite social. Given the political activism of both, it's quite obvious that they weren't actually disinterested in humanity itself. All in all, I think the 'insane genius' myth says more about people in general than about the geniuses. First, it displays our need for 'heroes', placing some people on pedestals way above everyone else, even though they're actually just at one end of a continuum. (Einstein was a genius, but was Niels Bohr? Feynman? Gell-Mann? Weinberg? Aage Bohr? Any Nobel-prize winner? Etc) Second, it illustrates a human tendency for 'justice'. People who are very smart must somehow 'pay' for that by having diminished ability in other areas. So geniuses are anti-social. Athletes are stupid. Etc. Sure, there are lots of 'geniuses' who were single-minded and anti-social, but there are those people on any job that doesn't require those skills. And as Alteripse said, there's a big difference between eccentric behaviour and real mental illness. Another factor might be cranks - people might reason along the lines of a crackpot simply being a genius who's wrong or misunderstood. (that's certainly how they see themselves!) A lot of them do seem to have some form of personality disorder, and they also seem to have a rather homogenous set of personality traits. (dogmatism, delusions of grandeur) But those personality traits aren't the ones that make a good scientist in the real-world. --BluePlatypus 20:40, 8 April 2006 (UTC)
As a friend of mine likes to say: "The line between genius and insanity is very thin. In Mexico, we call it the Rio Grande." Grutness...wha? 01:25, 9 April 2006 (UTC)
Someone asked me once whether I suffered from being crazy. I replied that I don't suffer, I love every minute of it. Of course, that was a quote from someone so I can't say I actually made it up, but it demonstrates a distinct lack of feeling by most people towards those who are different. I would never think I suffer from being like I am (ie. a crazy scientist :-) ), but others would instantly think that because they could never like my situation that I mustn't like it myself. Ansell 01:25, 9 April 2006 (UTC)
I think your comment demonstrates a certain lack of feeling towards those who have a genuine mental disorder. Many of them do suffer, profoundly. --BluePlatypus 03:50, 9 April 2006 (UTC)
 :-D I was speaking with tongue in cheek of course. Ansell 03:59, 9 April 2006 (UTC)
  • Boy, I just don't know where to start with this one. What exactly do you mean by "lunacy" or madness, anyway? I think we have to be careful to distinguish between mere eccentricity and clinical psychopathology. Just because a highly intelligent, academically oriented person has no social skills and little sense of fashion does not mean they are "nuts," although the tabloids would have us believe that was the case. And not all types of madness have been deemed favorable to achievment. The "mad genius" stereotype has been around for a long time, especailly as applied to artists. The art majors on college campuses know that they can get away with all sorts of odd behavior and have it explained away as a manifestation of "artistic genius." Similarly, slovenly, asocial maths geniuses are often excused for their faux pas because such things are somehow a mark of their superiority in the intellectual heirarchy. People like Kay Redfield Jamison have written books about the correlation between bi-polar disorder and certain types of "creative genius." And the media has been playing the "Asperger / Engineer" connection for about 10 years now. Correlation is not cause, however, and it may be that the reason some of these famous "mad" geniuses have been so productive is that, in addition to having psychiatric disorders, they were highly intelligent and highly motivated. This may have enabled them to not simply "work around" their problems but to incorporate some of their supposed problems into a successful combination of skills. For example, many math and music prodigies experience synaesthesia, which gives them a unique perspective and provides an alternate path to understanding their fields. Manic episodes allow some people to work compulsively for days on end until a particular problem or project reaches a satisfactory conclusion. I seem to recall some evidence that in the bi-polar brain, some of the excess neurochemicals that build up in one portion of the brain "spill over" into adjacent areas associated with creative and other activities. And depressives have been found to have an enhance ability to recognize the true consequences of personal and political actions. I'd better stop now. This topic seems to be making me feel a bit crazy. Ande B 09:02, 9 April 2006 (UTC)

The whole problem may be solved on a point of perception. Unless you believe in absolute normality, there really is no single frame of reference from which one may judge sanity. From the scientist's point of view, it may the casual person who is mad. This lunatic behaviour was only caught on the exaggeration of the media and the apparent inpenetrability of many famous scientists/mathematicians. In many cases, misunderstanding and misinformation has always tend to crowd scientists with an air of mystery which others, in failing to understand, classifies as 'eccentricity'. The problem is that scientists are not always interested in making the general public understand themselves, and thus solve the mystery.

Then one must stress that the scientist does not necessarily have a mental illness such as schizophrenia, but his novel ways of perceiving the world, and often autistic moods, sometimes decieves the passer- by into thinking that this is so. In many cases their ways of percieving the world may even be stereotypical enough to be one step from the ideas of a lunatic, save that it is also usually supported by reasoning. The truth is scientists are not always willing to conform themselves in order to undecieve others, and our society does not always enjoy the company of those that do not follow its rules. Luthinya 10:06, 9 April 2006 (UTC)

This discussion is too lengthy to be worth reading. The title thereof implies that every Nobel Prize winner, Fields Medalist, Wolf Prize inner, Shaw Prize winner, Abel Prize winners, etc. + inventor, computer designer, corporate leaders or anyone who didn't watch soap operas, sitcoms, party, and goof off is moron.Patchouli 02:03, 10 April 2006 (UTC)

Unfortunately, this is pretty much how most of our society tends to view especially technological geniuses. Don't get me wrong- I'm often avoided as a nerd for reading maths/physics books all the way through lunchtimes in my high school. Luthinya 10:29, 10 April 2006 (UTC)

dynamic programming[edit]

how to implement dynamic programming using 'c' language —Preceding unsigned comment added by 59.92.34.98 (talkcontribs)

Our article on dynamic programming is quite general; the ideas should be readily applicable to C. --Bth 14:27, 8 April 2006 (UTC)

C# Adding Machine[edit]

Please can someone give me the code required to make an adding machine in Microsoft Visual Studio C# 2005 express edition? Computerjoe's talk 12:53, 8 April 2006 (UTC)

sounds like a homework question. have you tried asking your classmates? Night Gyr 19:18, 8 April 2006 (UTC)
No, it's not a homework question. I'm a good faith editor, and I know this isn't the place to get h/w done. I'm learning C# by myself, and have made an adding machine before; but forgot the code. Computerjoe's talk 21:06, 8 April 2006 (UTC)
Then it should be easier for you to write it the second time. Bubba73 (talk), 01:47, 10 April 2006 (UTC)
wouldn't it just be a matter of creating code for each button, so pushing a key puts a number-symbol onto the end of a string, then when an operation key is pushed the string is converted to a number and the specified operation is performed? it doesn't seem to hard to write if you know how to create button controls. I know java and C/C++, not C#, though, so microsoft may be pulling something different. Night Gyr 05:56, 9 April 2006 (UTC)
Yep. I need to know the code to transform e.g. TextBox1 and TextBox2 into a string. This has float.Parse in I think. Computerjoe's talk 09:02, 9 April 2006 (UTC)
Er, turning the contents of a text box into a string? Should already be a string if it's in a text box. If you're really emulating a calculator (with graphical buttons to provide digits, particularly), you shouldn't be doing any string-parsing anyway. (Just handle the input yourself, forming 10x+d or x+d\times 10^{-n} in response to a digit d.) Then format floating-point numbers for output only, retaining the number for further computation. In other words, you want to do as few data-conversions as possible. (You also want to be using double precision, probably.) --Tardis 14:58, 10 April 2006 (UTC)

Poincare's radiation paradoxes[edit]

Hey folks! I was just reading Olivier Darrigol's paper from the journal Isis on the Einstein-Poincare priority dispute, and I came across the phrase "radiation paradoxes" as an item of importance. What are these radiation paradoxes? I'm a layman, so I was hoping someone could explain it in ordinary english. Thanks in advance! 65.95.139.89 18:49, 8 April 2006 (UTC)

The very short version is that if you try to work out the equations of electromagnetism -- particularly for the propagation of electromagnetic radiation (ie light) -- for different observers travelling at different speeds, but use Galilean relativity (that is, the intuitive idea that the speed of an object moving at \mathbf{v_{obj}} according to one observer is \mathbf{v_{obj}}+\mathbf{v_{obs}} according to another observer in whose reference frame the first observer is moving at \mathbf{v_{obs}}) you will get different answers for different observers -- hence "radiation paradoxes". Postulating an invariant speed of light fixes this, but forces you to use a more complicated equation for relative speeds (albeit one that is very close to the Galilean one at low speeds). --Bth 19:26, 8 April 2006 (UTC)

Diseases[edit]

How many diseases affect the man most and the woman most? —Preceding unsigned comment added by 70.53.95.183 (talkcontribs)

Red/Green Colorblindness is overwhelmingly male, since it is caused by a recessive gene on the X chromosome, of which women have 2 but man have 1 (They have XY instead of XX). 21:14, 8 April 2006 (UTC)
I'm not sure how to answer this question. Men, for example, are incapable of contracting cervical cancer. And with regards to "how many", you can't really say "six" as an answer. Could you rephrase? Isopropyl
Isopropyl is right; for more examples, see also Sex and illness. Melchoir 22:40, 8 April 2006 (UTC)

Thousands of diseases affect people of different sexes differently statistically for thousands of known and unknown reasons. In other words, it may be more unusual for a disease to have exactly the same sex distribution of the population than to have at least a small sexual association. alteripse 02:07, 10 April 2006 (UTC)

Data compression?[edit]

I was wondering, are there any lossy text compression algorithms? he he... it would be a bit like censorship if you think about it.--Frenchman113 21:12, 8 April 2006 (UTC)

Ys, thr prbbl r sm lss txt cmprssn lgrthms. --GraemeL (talk) 21:16, 8 April 2006 (UTC)
Pitman shorthand is another one. Four candles, anyone? --Heron 21:31, 8 April 2006 (UTC)
A lossy text compression system wouldn't be very much use, but if you wanted to play, you could run text through an mp3 or jpg compression system, and see what came out - the results would probably show you why there really isn't one in the sense you mean it. For great justice. 22:04, 8 April 2006 (UTC)
you could use abbrev. to repr. words. They lose some data (i.e. gain ambiguity) but as long as context makes up for it, you can save space at min. qual. loss--same prin. as other lossy algos. Night Gyr 06:01, 9 April 2006 (UTC)
  • If you have Linux, rm * gives 100% compression. -- Filliam H Muffman 03:55, 11 April 2006 (UTC)
  • Another linux option... cat file | tr -d ' ' whichwilleffectivelycutoutallthespaces.thiswillgiveyoumaybea10%sizereduction,butyoucouldprobablystillmakeoutthetextright?

--Jmeden2000 15:17, 12 April 2006 (UTC)

Another question[edit]

Hate to be a nuisance, but how can I force WMP to save video that's being streamed from the web? I'm totally missing something here...--Frenchman113 22:31, 8 April 2006 (UTC)

Try asfrecorder, http://sourceforge.net/projects/asfrecorder/ 202.58.62.4 00:27, 9 April 2006 (UTC)

Projectile, Missile, and Rocket[edit]

What is the difference among these?Patchouli 23:15, 8 April 2006 (UTC)

A projectile is any object launched into the air by any given power source (includes asteroids, arrows, cannoballs, meteors, etc). A missile is a projectile launched by a human (in the modern sense, usually an explosive-bearing rocket). A rocket is a device powered by Newton's third law of motion (exhaust=action, rocket movement=reaction). Hope that helps.--Frenchman113 00:02, 9 April 2006 (UTC)
In a general sense, a missile is a general term encompassing all human-launched projectiles, including stones flung from slings and shells from battleship cannons, but in a modern military context, it's the subset of rockets that have their own guidance systems, i.e. guided missiles. Night Gyr 06:04, 9 April 2006 (UTC)


Thank you.Patchouli 10:58, 9 April 2006 (UTC)

Many people disambiguate rocket and, say, jet engines, by the idea that rockets carry their own fuel and reaction mass. -Fangz

April 9[edit]

latex in xfig diagrams[edit]

I'm trying to make a diagram in xfig which includes some LaTeX formatted text. I'm following the instructions here.

Here's what I do:

  1. draw my diagram
  2. make a text box with text "$\int f(x)\, dx$"
  3. set the "special" flag to "special" of the text box
  4. choose export, then select "combined PDF/Latex both parts", then export, resulting in two files intbox_t and intbox
  5. change the filename of intbox to intbox.pdf; my system won't work without the extension
  6. change the line "\includegraphics{intbox}%" to "\includegraphics{intbox.pdf}%", so account for the change in filename above
  7. in my tex source file, I include the header "\usepackage{graphicx}"
  8. I input the file with "\input intbox3.pdftex_t"
  9. then I tell latex to do its work. It seems to find the file and import the pdf, but then it barfs with:


loading : Context Support Macros / PDF (2004.03.26)
) (./intbox3.pdftex_t <intbox3.pdf, id=1, 258.9675pt x 177.66376pt>
<use intbox3.pdf>
! Undefined control sequence.
\color ...vevmode \csname fi\endcsname }\@ldc@l@r 
                                                  
l.14 }}}}
         
? 

I'm using an Mac OS X system, using TeXshop frontend to pdflatex.

I'm a hair away from giving up. This is for a wikipedia article, so if you can straighten this out for me, you're helping grow an article. -lethe talk + 00:23, 9 April 2006 (UTC)

Are you using \input{intbox3.pdftex_t}? If you want to email me the sources I could have a look. I use TeTeX under Linux but it doesn't seem to be an operating system problem. Ansell 00:54, 9 April 2006 (UTC)
OK, I've sent an email. Thanks for taking a look. -lethe talk + 17:55, 9 April 2006 (UTC)

Another solution is to export the xfig doc in "LaTeX picture + epic macros" (or "eepic macros" if you need them). Then you have to \usepackage{epic} (or eepic), but everything is in LaTeX format from the start. So for the text you just put placeholders in the xfig doc, and then go into the exported source and hack the text in by hand. The biggest downside is that if you need eepic, it won't work with PDFLaTeX and you'll have to do the two-step process to get a pdf file, which may not have hyperlinks. --Trovatore 18:47, 9 April 2006 (UTC)

LASIK and losing vision[edit]

I overheard someone saying that you lose part of your vision or something like that when you have LASIK surgery, is this true?

Our article on LASIK might be helpful to you, in particular the Complications section. -- Daverocks (talk) 02:53, 9 April 2006 (UTC)

BMW Bluetooth[edit]

I have a BMW with bluetooth, and I had the code but I lost it. BMW says they dont have it and want $120 to retreive it from my car, is there any other way to get it? I used to use a motorola v600 and the code is in the phone, I just cant retreive it (I dont know how), how can I get the code?

Fortune cookie say: He who can afford BMW, can afford to get it fixed. --Zeizmic 15:19, 9 April 2006 (UTC)
Heh. But anyway, if you can get the code without paying, then so can anybody else. OMG CAR HAX!!!!1 Tzarius 09:40, 10 April 2006 (UTC)
I'm just waiting for the "Wikipedia - where car theives go for advice" story to crop up somewhere now. — ceejayoz talk 17:49, 13 April 2006 (UTC)
Try taking the phone to the dealer and ask him to retrieve the code from it...it'll probably be a lot cheaper and faster.. :) Jayant,17 Years, Indiacontribs 18:10, 13 April 2006 (UTC)

Cloning[edit]

Is it possible at this time to produce a clone of someone?

I think so, yes. According to the article on human cloning, ACT was the first to sucessfully clone a human embryo. There are many claims of success beyond the embryo stage, but none of them have been verified. --Bowlhover 04:54, 9 April 2006 (UTC)
No, not quite, but we are getting close. Part of the problem lies in defining "clone" in a consistent way, and the media has failed to do this. But I assume you mean "Is it possible to make a human being who would have the exact DNA as another." In a somewhat trivial sense, the answer to that is yes. We have long had the ability to perform artificial insemination in a culture dish. And one of the most frequent reasons to do this is to avoid conceiving children with an inheritable disease. By removing a single cell from the early zygote, and allowing that cell to grow for a while before (destructively) analyzing its DNA, we have created a clone of the original zygote. Many such clones can be made from these early embryonic cells and each of them has the potential of growing into a healthy human who would have DNA identical to the other humans who were derived from that same original zygote. But making a human clone from an adult does not yet seem possible with current techniques and understanding. Just convincing the early cell to make the initial divisions has been problematic. Developmental biology is not a simple field. In fact, it's in its infancy. Until we understand the numerous developmental hurdles and chemical cascades that determine human development, we wont be able to undertake this task without high risk. Once we do reach that stage of technological capability, the entire process will likely seem so incredibly obvious we'll be baffled at why it took us so long. Ande B 09:18, 9 April 2006 (UTC)
Yes, but I have a feeling that it's going to take us a very long time to reach that stage, certainly much longer than needed. The world's most advanced nation, the U.S., has prohibited federal funding for human cloning research. Some U.S. states have even banned all forms of human cloning. Religion got into the way of scientific research, just as it did in the past. --Bowlhover 17:35, 9 April 2006 (UTC)
The world's most advanced nation, the U.S.
(much coughing and spluttering and muttering about damn Yankees) ;) — QuantumEleven | (talk) 09:31, 10 April 2006 (UTC)

How accurate are the Heavens Above predictions?[edit]

In terms of time, how accurate are the Iridium flare predictions? I know my latitude, longitude, and elevation to within 30 m, so the errors in my position shouldn't affect the results too much.

I'm curious about this because I plan on photographing tomorrow night's magnitude -2 flare, using a 15-second exposure time. I'm going to use an accurate clock to tell me when to press the shutter button--there needs to be 7.5 seconds of exposure before maximum brightness, and 7.5 seconds after. --Bowlhover 04:42, 9 April 2006 (UTC)

I successfully photographed the iridium flare whose maximum brightness was at 21:17:08 (according to the Heavens Above prediction). Here is the 4.1-megabyte photograph--the flare is the streak of light in Cepheus, and to the left of the photo is Cassiopeia. I pressed the shutter button at 21:17:00, so the shutter opened at 21:17:02 due to the 2-second self-timer. It closed at 21:17:17. As you can see from the photograph, the flare was already very near its maximum brightness when the shutter opened. So the prediction was off by about 5 seconds. --Bowlhover 02:22, 10 April 2006 (UTC)
Nice work! Ande B 21:14, 11 April 2006 (UTC)

Tinted CD-Rs[edit]

I saw and purchased some tinted CD-Rs yesterday in Taipei. The writing surface of these discs is in bright orange or bright green (they are colored like highlighter marker pens) and they cost NTD6 each (less than US$0.20 cheap). Do they employ newer dyes? Or are they just ordinary CD-Rs with tinted polycarbonate plastics? -- Toytoy 07:15, 9 April 2006 (UTC)

I actually just saw one of those the other day for the first time. As you guessed, it's just tinted polycarbonate. Chapuisat 15:08, 11 April 2006 (UTC)

Open University Recommendation[edit]

Can anyone help in recommending a free Open University that allows under- 18 pupils to enjoy the studies of Mathematical Modelling and Theoretical Physics? I shall be deeply grateful for any suggestions. Luthinya 10:10, 9 April 2006 (UTC)

If you want an Open University, you're probably in the UK, but MIT has a lovely site over at OpenCourseWare, where lecture notes and readings and other materials are posted. Isopropyl 15:38, 9 April 2006 (UTC)

Angular Momentum[edit]

In a book I have read recently concerning the spin of subatomic particles, I have heard Max Born say that though particles do not actually have spin in the usualy sense of the word, yet they still behave as if they have angular momentum. I am afraid I have not been able to decipher this remark, and shall be grateful if anyone may help in understanding it. Luthinya 10:15, 9 April 2006 (UTC)

Subatomic particles do have angular momentum. They can rotate about a linear axis in three dimensions, with such rotation obeying conservation of momentum, affecting collisions (although not always the same as for molecules and solids; baryons and fermions are very different in this respect because of their different properties) and wobbling with gyroscopic effects including when rotation interacts with field effects such as electromagnitism. Particles also have quantum spin which is a quantum number which is completely disjoint from angular momentum. "Spin" was named after experiments with polarization suggested that the quantum number was similar to angular momentum. As a quantum number, spin has conservation laws based strictly on small or simple fractional multiples of integers. Note that the angular momentum of a low-mass electron is unlikely to ever have much of an affect on its behavior when compared to electrostatic forces. For nuclons, though, angualr momentum can be very significant. See, for example, Cold fusion#Current understanding of nuclear processes. --James S. 11:30, 9 April 2006 (UTC) This is a bad explanation for several reasons. Please see Spin (physics), Spin quantum number, and Angular momentum. --James S. 13:15, 9 April 2006 (UTC)
  • Ok, well.. There are a lot of levels of explaination that could be given here. The simplest, most common one is to describe spin as 'intrinsic angular momentum'. That is, an amount of angular momentum that is built-in to the particle, so to speak. So spin does work 'as if they have angular momentum', but it's a different property. (they can, however, interact. (Spin-orbit coupling) --BluePlatypus 01:49, 10 April 2006 (UTC)

Sheep[edit]

Can a human physically make a sheep pregnant by sexual intercourse?

No, in general, different species can not interbreed. (But he can try.) --James S. 11:17, 9 April 2006 (UTC)
But, but I can make it happen. It's actually doable.
Give me some sexually matured male sheep and female sheep. I can physically force the female ones to pregnant. In fact, they may just go pregnant with or without my efforts. -- Toytoy 14:30, 9 April 2006 (UTC)

See Hybrid and Horizontal gene transfer and HeLa (a single cell species created by humans from a human) for interesting examples of what is possible, and Category:Mythological hybrids for what people used to think was possible. WAS 4.250 14:44, 9 April 2006 (UTC)

Chimera (genetics) is also an interesting read. Isopropyl 15:36, 9 April 2006 (UTC)
Do I detect a sense of urgency in this question? I hope not. Phileas 06:19, 10 April 2006 (UTC)

astronomy - colour correction[edit]

In colour images taken of the night sky, do astronomers ever attempt to correct the colours to allow for redshift? Obviously this would be tedious, difficult and probably impossible where the redshift of objects is not known. However for something as large as the Orion Nebula, is this ever done? --Paul venter 14:34, 9 April 2006 (UTC)

  • The Orion Nebula is in our own galaxy, and therefore can be expected to have a negligible redshift. In general, quite a bit of processing is done on most astronomical images, and correcting for redshift would be relatively easy. See this link for information about how the Hubble Space Telescope does it. In any case, computing an object's redshift is relatively easy; if you have a spectrograph, you're most of the way there. -- Filliam H Muffman 03:14, 10 April 2006 (UTC)
You don't even need (expensive and time-consuming) spectroscopy; if you have good photometry at multiple wavelengths you can get a reasonable estimate from photometric redshifts. (We should have an article on them; maybe I'll add it to my to do list.) --Bth 07:17, 10 April 2006 (UTC)

Can we defeat radiocarbon dating?[edit]

Can we defeat radiocarbon dating? I think it is very possible.

  • Build a totally enclosed greenhouse similar to the Biosphere 2 (with positive pressure).
  • Buy lots of coal.
  • Grow Cyperus papyrus in the greenhouse using hydroponics equipments.
  • Burn the coal to provide 12C-rich CO2.
  • If you need other organic fertilizers, grow alfalfa at first and use it as the fertilizer.
  • Make your papyrus with your 14C-poor Cyperus papyrus.
  • Let an expert create the forgery.
  • Hire an antique dealer to inform scholars.
  • Let them see the v1.0 fake which may not be good enough.
  • Let the antique dealer to ruin the deal.
  • Let the forged item sit in a bank safe for years.
  • Take your time to create and age your v2.0 fake to the desired status of corruption.
  • Let the scholars buy it.

I think you can always find cheap and aboundant materials that are not polluted by post-WW II radioactive fallout (e.g. antartic ice to provide water). Scientists can only conduct destructive tests on unwritten parts of the speciment. I guess you don't even need to make 14C-poor ink. I think it is possible to make something to defeat 12C and most other scientific dating techniques. You can mass-produce multiple copies of the forged document (each created and aged a little differently) and test them with all the tools available. The copy that can fool all tests will be released to the scholars. Maybe you can breed your own "ancient" Cyperus using DNA fragments extracted from real antiques. - Toytoy 16:09, 9 April 2006 (UTC)

I like it! Seems like it would be possible, but with your method the forgery would be just as old as the coal you bought (by C-14 dating). I'd add another step about regulating the C-14 concentration by adding outside CO2 to get just the right date you want for your papyrus to have died. -Snpoj
Yes, you're right. I'll build a window. It's easy to regulate the amount of 14C. You can build a window or buy some charcoal. You may also want to filter your coal burner because unfiltered smoke may contain too much sulfur. Anyway, I think it is very possible to cheat scientists. All you need is a great expert of ancient literature. You can open the window and harvest your Cyperus every 12 hours. Sooner or later, you'll get a batch of Cyperus that's dated to the desired time period. These grasses are growing fast! Maybe you can sell the unused but dated portions to other law breakers! :) -- Toytoy 16:37, 9 April 2006 (UTC)
But why fool scientists now if you can fool them thousands of years in the future? Why rewrite the past when you rewrite the future!? Using a mass spectrometer, isolate C-14, burn it and infuse it into the atmosphere of the dome. Now when the papyrus dies it will have a healthy stock of C-14 with which to pass the time. Eventually, in the year xxxx so much C-14 will have degraded as to appear that our Cyperus died just last year in xxxx-1! Now in the year yyyy documents written by us on the Cyperus back in 2006 will be found. The unsuspecting scientists will believe they must rewrite the history of xxxx with our falsification and we'll be laughing in our forgotten graves! -Snpoj 03:48, 10 April 2006 (UTC)
I don't think anyone claimed it to be impossible, either. But you leave out the problems with aging. There are no doubt chemical markers (e.g. various decomposition products) which can be used to distingush something which has aged normally and something which has been bleached or similar. Then there are of course all the other usual methods of detecting a forgery. I don't think radiocarbon dating is terribly important for dating documents either - from what I understand from reading bibliophile literature, old paper is in relatively good supply. --BluePlatypus 18:00, 9 April 2006 (UTC)
Unfortunately the problem you have is that C-14 is created from C-12 by solar raditation.

http://www.ndt-ed.org/EducationResources/CommunityCollege/Radiography/Physics/carbondating.htm Thus the ration of C-14 in your papyrus would still have the correct C-14. Now add to the fact that your Ancient language experts are few and far between. Most of them are scholars, and they all know each other. -Tollwutig 14:56, 10 April 2006 (UTC)

If you build a greenhouse at near sea level, and you burn fresh coal to produce fresh 14C-poor CO2, solar radiation can do nothing. To create 14C, you need high energy cosmic ray that's only available very very high above.
You can always obtain genuine unused ancient papyrus or Chinese paper from antique dealers. In fact, many high-end Chinese art counterfeiter have their personal stockpiles of unused paper aged for at least a couple hundred years. However, if you have an endless supply of 14C-poor papyrus, you can mass-manufacture history-making documents and age them by a trial and error approach. If you take time and money to do it, you will have some really great speciments in a few decades that can fool almost everyone on Earth.
This method is surely difficult. An ordinary counterfeiter will not do it, but a determined government or religious group may have the will, expertise, time and resources to create something to support its own position (we own this land, we are better than you, our god was ...). -- Toytoy 15:41, 10 April 2006 (UTC)
  • I have an even better idea, I could just use my time mahcine to go back to 1192, and drop off a reem of printer paper in an easy to find location, then travel back to the future, and pick it up there after it's had a few thousand years to age, then write whatever the heck i want to on it —Preceding unsigned comment added by 64.12.116.74 (talkcontribs)
With your specifics I take you are discussing the recent Gospel of Judas release by National Geographic? If so you'll have a hard time finding someone who knows Coptic, there are what 5 people who can readily translate it?--Tollwutig 19:50, 10 April 2006 (UTC)
You're damn right. I am very skeptical to the NG's Gospel of Judas TV show. I think it is difficult to create such a scholar bait but that's not totally impossible. In my opinion, NG failed miserably by creating a two-hour-long show that does not interview reasonable skeptics. I mean they jump to the conclusion too soon or they want the audience to buy the theory that the Passion could be simply wrong.
Logically, you may also say the Gnostics had build a myth to counter other Christian sects or you may even say both sides lied when they talked about the death of Jesus. NG failed to present a more neutral POV with their dog and pony show. It didn't even say Jesus could turn himself to the Romans rather than asking Judas to betray him. The NG is telling a lousy detective story.
As to the "only five people on Earth could write ancient Coptics" statement, I really cannot disprove it. However, I am very skeptical. Let's say the text was created by a counterfeiter. If you put it down in ancient Greek, the expert pool will be much more larger and there will be more skeptical eyes to review your text. And by the way, I don't think ancient Coptics is some sort of regulated language. You don't need a license to learn it. You just don't see many college job offers. A determined person previously trained in related languages may learn the language from various sources. Logically, you may also say some Evil Theologist discovered a Medieval Coptic text that tells such a story. He hired an Evil Linguist and an Evil Scientist to rewrite the text to match 3rd century grammer and put it on a piece of 3rd century papyrus to make the text closer to truth. Did I ever mention the Black Helicopter?
Personally, I have only seen statements such as: GoJ said Judas was not a bad guy. The existence of the GoJ was proven by ... . I did not see them to advertise other previously unknown findings from the GoJ. If you unearth a document like this, I expect to learn some unknown things that are trivial in scope such as "The Apostle Peter had ulcer." or things like this. I don't think all genuine documents shall carry such information, but a forger may invent a story with all known facts and insert just one think to prove his point. After all, I think NG failed to take a more neutral stand in this case. It only took me minutes to devise a way to counter 14C dating. To a determined expert with money to burn, it could be even easier. The NG shall be more careful and skeptical with their discovery. -- Toytoy 00:31, 11 April 2006 (UTC)
  • Frankly, you seem to have a little bit of a chip on your shoulder about this, Toytoy. If it makes you feel any better, just because the document is authentic doesn't mean you have to believe what it says. Why not just say "this is what the Cainites believed but they were full of crap", instead of camping out on the grassy knoll? --Trovatore 00:46, 11 April 2006 (UTC)
I believe some questions can never be fully answered even if we travel back in time with all kinds of evidence collection tricks and tools. If we cannot fully answer today's questions, how can we be so sure about yesterday's unsolved mysteries?
However, I think some scholars are extremely gullible. I have first hand experience with an easily debunkable pre-Columbus historical discovery. Some scholars, I mean some of them, are just too eager to believe.
Based on what I have seen, I believe the QC Dept. of the National Geography Society failed to do their job. Instead of showing us non-experts a less loaded version of the story, they made the show as if it was almost the truth. It didn't answer some trivial questions. I think it is natural for some earlier sects to pro Judas and some others to bash Judas. A skeptic may require more solid evidence before jumping on the band wagon. Too willingly to accept can lead to miserable mistakes. Do I have to make up a text that says "All apostles other than Judas betrayed Jesus. They took the money and framed Judas"? If you're willing to believe, someone somewhere may be willing to cook you some tasty truth.
If the text was genuine, it would be more insightful to study the societal structure of the writers rather than to ship us another version of the truth. I mean the original Gospels were created by the 1st generation followers. By the time the stories travelled to Egypt, it must had been modified a little bit here and there to please local Christians. It's like making locally adapted versions of Hamlet for 17th century Japanese or 18th century Persian viewers. -- Toytoy 07:02, 11 April 2006 (UTC)
Popular presentations of academic subjects, particularly on TV, tend to be slanted towards providing some sort of "narrative" (often, as in this case, "everything you thought you knew is (probably) wrong", though "person X's wild speculation is vindicated centuries later because it happens to sound a bit like what we now understand" is also popular), and have been for decades now. All that's happened is that you've seen one that touched on a subject that you have some knowledge of, or at least strong feelings about. Almost every show like this makes people who know the field feel the way you do right now. You should probably bear that in mind next time you watch one.
On the other hand, I'm fairly sure I was aware of these ideas about Judas having been around in some of the now-extinct branches of Christianity well before this flap, so I'm not sure there isn't something in it. --Bth 07:20, 11 April 2006 (UTC)

Inductance[edit]

How to make 1 henery inductance coil?

Did you check induction coil? I don't know what a Henry or Henery induction coil is. -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 12:46, 10 April 2006 (UTC)
The henry is the SI unit of inductance. --Bth 13:25, 10 April 2006 (UTC)
Here's a site which discusses design and construction of coils. EricR 14:02, 10 April 2006 (UTC)
Self of Solenoid

L= (m0mr S N*N) / l An above Equation can use to calculate a self of a coil with the defined length and l>> D( D : is a diameter of the coil, S: Surface of coil ; S= (1/4)*4*3.14 D*D) m0= 4*3.14*10-7 ( here mr=1, a core is air ) Supposed: S=4cm2 = 4*10-4 m2 N= number of turn ( round) l= length of coil= 10cm=0.1 m For L =1 H , we must have N= 4461 rounds --User:Ngocthuan 06 18:25, 10 April 2006 (UTC)

April 10[edit]

electrical potential of the sun[edit]

My question is based on the following, which is from "Beyond Velikovsky", by Henry Bauer, page 59. He says that Velikovsky attributed some things to electromagnetic forces between astronomical bodies. In particular, in 1952 astronomer Donald Menzel calculated that the potential of the sun would have to be 10^19 volts to account for some of Velikovsky's claims (also in Worlds in Collision), which Menzel said is impossible. In 1960 physicist V. A. Bailey (unaware of Velikovsky's work and Menzel's calculations) proposed a theory that had (as a consequence) a potential of 10^19 volts for the sun. Bailey found a mathematical error in Menzel's calculations.

I have two questions: (1) what became of Bailey's theory? (2) What is the electrical potential of the sun (if it is known)? Bubba73 (talk), 01:42, 10 April 2006 (UTC)

Take a look at Electric Universe. ☢ Ҡiff 02:10, 10 April 2006 (UTC)
I can't find any mention of Bailey's theory there, or the Sun's potential. Is Bailey's theory part of the Electric Universe theory? Bubba73 (talk), 02:18, 10 April 2006 (UTC)

"[The "electric star" model proposed by Ralph Juergens in 1970s (in Pensee II, IX & X, SIS Review, & Kronos) and revived by Wallace Thornhill in The Electric Universe (1998), part of his "holoscience" project, (in which the Sun is a non-convecting, isothermal ball of plasma powered by infalling galactic electrons and many craters in the Solar System are the result of gigantic electric discharges, etc.) [as deus ex machina] cannot rescue the "polar configuration" from its fatal flaws because the model is a non-starter. It is disproved by practically everything known about the actual behavior of the Sun and heliosphere. This was first explained by this writer in Kronos X:3, 1985, pp. 15-23, and recently in more depth on e-mail list-serves by Robert Grumbine, Karl Hahn, Burch Seymour, Tim Thompson, and Wayne Throop. Thornhill either ignores or dismisses all the negative evidence such as (i) the absence of x-rays in coronal holes (which should be produced by infalling electrons for which no evidence exists beyond the wishful thinking of Thornhill and star-struck acolytes such as Amy & Mel Acheson writing for Thoth and Atlantis Rising, and Don Scott, an electrical engineer, who in parroting Ralph Juergens in Kronos IV:4, 1979, also fails to understand the importance of the Reynolds Number in defining turbulence in photospheric granulation.), (ii) the proof that granulation in the Sun's photosphere is an expression of convection, (iii) the mere existence of the solar wind in which no inflowing electrons have been detected, (iv) the absence of characteristic particles from the nuclear fusion claimed to occur in the photosphere, etc., etc. The model lacks rigorous mathematical support. No one has ever shown that the electric charge required to produce the cited craters, e.g., Aristarchus on the Moon, is feasible, while rigorous mathematical modelling to explain the high temperature in the Sun's corona, a favorite anomaly cited against standard theory, in conventional terms is progressing steadily. The simplistic analogies to plasma and electrical discharge phenomena that are invoked to support the model [as in Talbott & Thornhill's Thunderbolts of the Gods (2002)] cannot nullify the verdict of the overwhelming negative evidence and serve only as an example of invincible ignorance, showing the proponents do not know, for example, the difference between a plasmoid and a pair of opposed lotus blossoms used by the Greeks to represent the thunderbolt held by Zeus. Other examples of so-called electric discharge effects on planets, asteroids, and satellites (such as Europa) can be explained by conventional means without invoking cosmic electricity.]" from AN ANTIDOTE TO VELIKOVSKIAN DELUSIONS WAS 4.250 12:46, 10 April 2006 (UTC)

http://www.asap.unimelb.edu.au/bsparcs/physics/P000031p.htm doesn't seem to identify this theory with BAILEY, Victor Albert although it seems to be a list of all his papers. WAS 4.250 12:46, 10 April 2006 (UTC)

This page of notes for a Velikovskyite essay references a Nature paper by Bailey from 1960 which isn't on that list: vol 186, p508. Not in any online archives that I can see, annoyingly. But it's probably the paper in question here, if anyone can get to a good library. --Bth 13:16, 10 April 2006 (UTC)

Science. RF Power Measurement.[edit]

Dear Sir/Madam,

I wish to know in detail the method of RF power measurement in different modes such as a. Timeslot Mode b. Continuous Average Mode c. Buffered Continuous Average Mode d. Burst Mode & e. Scope Mode

Kindly help.

Regards Pavan

Our article on Radio frequency might be of interest to you, as well as this page about measuring RF power. -- Daverocks (talk) 09:02, 11 April 2006 (UTC)

Website Hosting[edit]

Is it possible to host your own website on your own computer? Would this require a fixed IP address? Is it possible to demand a fixed IP address from your ISP? --Username132 (talk) 05:22, 10 April 2006 (UTC)

To answer my own questions, yes it is possible and a fixed IP is not necessarily necessary. http://www.no-ip.com for example, offers ways around dynamic IPs, although I don't really understand how it works (anyone else?). Some ISPs offer a fixed IP as standard or for an extra fee, or even not at all, but some users report that they have had the same IP for up to two years even with switching equipment on and off multiple times. What is it that dictates when a persons IP is changed?
Would an admin on this website be able to compare the IPs used to make my first ever edit and this edit I'm typing now, for me? There may be other IPs inbetween due to editting done at university accomodation. Thanks :) --Username132 (talk) 06:31, 10 April 2006 (UTC)
I've used http://www.dyndns.org which gave me a domain name that I could attach to my (current) IP. I also had a program running on my computer that constantly updated the information about my current IP to dyndns, keeping the domain name attached to my computer. I would assume no-ip works like this, too. My current hardware firewall is also capable of updating its IP to dyndns by itself. –Mysid 06:40, 10 April 2006 (UTC)
Thanks. I have the option of
a) hosting through the WinXP machine my mum uses; or
b) hosting through a Proliant 3000 server with Fedora Core 4 installed which would then have to relay internet access to mum's computer as required.
Is setting up a web server difficult? I'd like to be able to receive email to my domain name aswell. --Username132 (talk) 07:24, 10 April 2006 (UTC)
Setting up a web server is not trivial - especially as you want to configure it so that it's secure against attacks - but with a bit of knowledge and lots of reading of help documents, it should be doable. Check out Apache HTTP Server, the most popular (and free!) webserver available. If you want to receive e-mail through your domain, you need to also run (at the same time) an e-mail server on your computer.
A more general note - is there a reason why you want to set up your own server? There are plenty of hosting sites which offer you ample web space, already set up, for a modest monthly fee - most of these have e-mail facilities, too. Obviously, it's up to you, I'm just wondering if you're not going to more hassle than you need to. Also, you need to make sure your server is on 24/7, and that your internet connection can handle the outgoing traffic. For instance, an ADSL connection can only handle very limited outgoing traffic, you can easily saturate your link if you are serving large files or many users. Just something to think about. — QuantumEleven | (talk) 09:28, 10 April 2006 (UTC)
Admins can't see your IP, only developers and those with checkuser access can. If you want to see what your public IP is, go to DNSstuff.com. -- Finlay McWalter | Talk 14:39, 10 April 2006 (UTC)
I see. I wanted to know what my IP was a few months ago and I don't think there's anyway to do that except contact a forum where I posted. I'll try somewhere else. --Username132 (talk) 16:42, 10 April 2006 (UTC)
To see your IP address as the Wikipedia servers see it, click here and wait ten seconds. Note that this logs you out of Wikipedia, so you'll have to log back in afterwards. —Ilmari Karonen (talk) 12:14, 11 April 2006 (UTC)

Some questions about C programming.[edit]

Well here are some of my doubts about some basic concepts of C programming. I have divided them in different queries.

QUERY 1)


i have two programs prg1 and prg2 as follows

//prg1 main() { int i,j,k; }

//prg2 main() { int i; }

First i compile (not run) prg1, then i compile prg2. Now, after the compilation of prg2 is over, what happens to the space which was reserved by variables like j and k? As we have not used memory allocation functions, does that memory get freed on its own?

If you don't run either of these programs, the memory used by them isn't relevant. The compiler certainly allocated some memory to deal with your source code, and probably had the names "i", "j", and "k" written down somewhere (except not "j" and "k" for prg2, of course!). But once you've compiled them, the compiler has exited and all that memory has been long since released to the operating system. --Tardis 18:30, 10 April 2006 (UTC)

A second question about this same query, in any of the above programs, when i would print the values of any variable i,j or k, a random or garbage value would be printed. But wat is the basis of that random value? I mean some logic would have been built up in the writing of the code for the functions like rand() srand(), etc. So wats the logic there and also here?

Garbage values and random values are totally different. Random numbers are supposed to be evenly distributed and to have no pattern. Garbage probably will have a pattern, but not a dependable or useful one because it's just what happened to be left over from the last program to use that memory. —Keenan Pepper 16:46, 10 April 2006 (UTC)
Variable declarations in C literally assign a name to a chunk of memory. That physical memory already existed (as in silicon), and had something stored in it: possibly all 0s, or maybe the hex pattern 0xDEADBEEF, or part of the Wikipedia logo. The point is, you have no control over it, so you shouldn't assume anything about it. --Tardis 18:30, 10 April 2006 (UTC)

QUERY 2)


Now this one is about arrays. consider the following statement,

int a[x]; //x is a valid no., i.e non-negative, etc. etc.

now wat is the limit of "x", wat is the maximum value of "x" which i can use? Or does it not have any limits?

First, note that in standards-conforming C, x must be a compile-time constant; not even
const int x=10;
will work. But assuming you didn't mean a variable "x" but just some quantity, Keenan's prior comment below is (mostly) right. --Tardis 18:30, 10 April 2006 (UTC)

Secondly, if "x" has a limit, on what does it depend? Does it depend on the type of array, like here its an integer array, so does it depend on the type of the variable defined?

It depends on how much memory is in the computer you run it on. If it's too big, it will compile, but when you run it the memory allocation will fail and your program will crash. —Keenan Pepper 16:48, 10 April 2006 (UTC)
It only depends on the type of the array in that 5 doubles may take up more space than 5 shorts. Also, if it's initialized, or if the operating system/executable file format require it, the memory may become part of the executable file, and perhaps may be part of the compiler's memory space. Then it would fail to compile, or it might fail to be written to disk for disk space reasons. Beyond that, it's restricted by the data type of array indices. In Java this is int, but in C it might be size_t instead (check a book). --Tardis 18:30, 10 April 2006 (UTC)
Explore your system. Make files a10000.c, etc:
a10000.c is void main(){int a[10000];printf("10000\n");}
a100000.c   void main(){int a[100000];printf("100000\n");}
a1000000.c  void main(){int a[1000000];printf("1000000\n");}
a10000000.c void main(){int a[10000000];printf("10000000\n");}

Run. On MY system:

 -> ./a10000
10000
 -> ./a100000
100000
 -> ./a1000000
1000000
 -> ./a10000000
Segmentation Fault (core dumped)

On unix, now see the ulimit command. Explore variations on the theme, try long instead of int, etc. Contemplate the implications for portable programming. GangofOne 22:08, 10 April 2006 (UTC)

main() should return int, not void. —Keenan Pepper 00:03, 11 April 2006 (UTC)

QUERY 3)


This one is about memory addresses and pointers.

Consider following:

int i; printf("%u",&i);

Now, whenever the address of "i" is printed, its always less than 65524 (or some value near that). Why is it so? even if many variables are created, each variable's address value would be less than 65524. Why is it so? Is it because of the reason, that the disk segments are always divided in sizes of 65524 units?

First, pointers are properly printed with the '%p' conversion specifier. It has nothing to do with disk organization at all; perhaps the best answer is "don't print pointers because they won't mean anything". Pointer values will differ between different systems, will differ because of compiler choice or different compiler options, may differ between different runs of the same program (simultaneously or in sequence), and don't have a well-defined association with any particular point in physical memory (see virtual memory for more on that). As a stab at answering your question, 65524 is very close to 2^{16}=65536, automatic variables are typically located on the call stack, and such stacks often grow downwards in memory; perhaps you have a 64K stack, and your pointer is (for any of a variety of reasons) relative to the bottom of that stack's memory area. --Tardis 18:30, 10 April 2006 (UTC)
Explore your sytem. while(i<1000000}{printf("%p ",&(i++));) This will generate another question in your mind. Write a program to answer it. This will generate another question... Repeat until (2038 AD). GangofOne 22:08, 10 April 2006 (UTC)

the structure of a dimerized pair of thymine molecules in a chain of DNA[edit]

could you please draw me this structure?

Can you use Google Image search? --Tardis 18:35, 10 April 2006 (UTC)

car audio - necessity of a capacitor[edit]

i was considering getting a small subwoofer for my girlfriends car to improve the sound quality. we listen to the music loud sometimes, but i mean it doesnt have to be ridiculously loud, just sound a little clearer when the volumes up and hear the bass tones a little better. anyway i talked to my dad about this because his neighbor runs a car audio store, but its a 'pimp my ride' kind of place (hes from romania). my dad said that it will need an amp and a capacitor. i know ill need an amp but do i really need a capacitor for a small subwoofer? i feel like i cant trust his opinion because his last car had a tv that slid out of the dash, this ridiculous sound system (my dad doesnt even listen to music) that soudned terrible when it would be put up loud to impress you, and vertical doors (he now admits the vertical doors were a mistake) anyway im sure ive seen many cars with subwoofers and no capacitors. my question is at want point do you have to install a capacitor, and for a small single amp will i need one? modesty 22:02, 10 April 2006 (UTC)

The purpose of a Cap is, like in any load circuit, to buffer power between a source and a load. A cap allows the voltage drops from the battery or alternator to be filtered out, which is important if you are running a lot of power. If the amp is running only 200-300W RMS (likely for a single sub 10-12") then there is generally enough capacity in the battery and alternator, so a big external cap is superfluous. Once you get past 500 WRMS is when you see issues with voltage drop along the wiring, and overloading of alternators and batteries (to the point of destruction) so extra provisions (a cap is among them, but shouldn't be the first) may be needed. --Jmeden2000 15:36, 11 April 2006 (UTC)

thank you --modesty 19:11, 11 April 2006 (UTC)

"The Critter"[edit]

I was reading a book about the Vietnam War the other day and a section of the book referred to the portion of the war in Laos. The author of the book referenced a certain animal that one of the other Americans had as a pet. For a long time nobody knew what the animal was called until one of the people stationed there happened to see the animal "Critter" on a Laotian postage stamp with the name "Panis Auritas". I can find no information on this animal.....I did find a picture of the postage stamp but no "Critter". Can anyone help with this information search.--67.98.38.212 22:53, 10 April 2006 (UTC)Benny

so what was on the postage stamp? alteripse 22:56, 10 April 2006 (UTC)

It looks a lot like a Pangolin to me -84.9.46.44 23:14, 10 April 2006 (UTC)

...which is genus Manis. I suspect a typo somewhere down the line. There is such a thing as a golden pangolin (though I note it's not listed in the Pangolin article), which might well have something like Manis Auritas as its taxonomic name. Grutness...wha? 02:31, 11 April 2006 (UTC)

April 11[edit]

Electromagnetism and force?[edit]

I have read in some places and seen some examples that electro-magnetism , specifically ionised air and static electric fields can move objects of any kind of matter. and also is the radiation pressure of light [which i know can move matter as have read article in scientific american on it] electromagnetic. How does it work if it does. I think it does as have read an interesting article on it. Am looking into it as a skeptical answer to poltergeist phenomena. this is the interesting article. it is about an electrostatic wall

".7 CASE STUDY - LARGE PLASTIC WEB ELECTROSTATIC PROBLEMS, RESULTS AND CURE, D. Swenson, 3M Company Tremendous static charge generation on a plastic web causes unique physical phenomena and special problems. Solution was simple and cost effective.



David Swenson of 3M Corporation describes an anomaly where workers encountered a strange "invisible wall" in the area under a fast-moving sheet of electrically charged polypropelene film in a factory. This "invisible wall" was strong enough to prevent humans from passing through. A person near this "wall" was unable to turn, and so had to walk backwards to retreat from it.

This occurred in late summer in South Carolina, in extremely high humidity. Polypropelene (PP) film on 50K ft. rolls 20ft wide was being slit and transferred to multiple smaller spools. The film was taken off the main roll at high speed, flowed upwards 20ft to overhead rollers, passed horizontally 20ft and then downwards to the slitting device, where it was spooled onto shorter rolls. The whole operation formed a cubical shaped tent, with two walls and a ceiling approximately 20ft square. The spools ran at 1000ft/min, or about 10MPH. The PP film had been manufactured with dissimilar surface structure on opposing faces. Contact electrification can occur even in similar materials if the surface textures or micro-structures are significantly different. The generation of a large imbalance of electrical surface-charge during unspooling was therefor not unexpected, and is a common problem in this industry. "Static cling" in the megavolt range!


On entering the factory floor and far from the equipment, Mr. Swenson's 200KV/ft handheld electrometer was found to slam to full scale. When he attempted to walk through the corridor formed by the moving film, he was stopped about half way through by an "invisible wall." He could lean all his weight forward but was unable to pass. He observed a fly get pulled into the charged, moving plastic, and speculates that the e-fields might have been strong enough to suck in birds!


The production manager did not believe Mr. Swenson's report of the strange phenomena. When they both returned to the factory floor, they found that the "wall" was no longer there. But the production workers had noticed the effect as occurring early in the morning when humidity was lower, so they agreed to try again another day. The second attempt was successful, and early in the morning the field underneath the "tent" was strong enough to raise even the short, curly hair of the production manager. The "invisible wall" effect had returned. He commented that he "didn't know whether to fix it or sell tickets."

- Bill Beaty

It later claims that this could be ionized air? how would this work? Robin

The story was made up. -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 01:21, 11 April 2006 (UTC)
Here's the origianl onlien, it was easy to google. http://www.amasci.com/weird/unusual/e-wall.html which references http://www.esdjournal.com/articles/final/final.htm , with pictures. GangofOne 02:14, 11 April 2006 (UTC)
FYI amasci.com is the site of User:wjbeaty, mentioned above.

Uuuuuum so now we have established that i didnt make the story up and its from a competant source, exactly how would it work? or am i just gona get accused of fraud again instead of getting the answer i asked for? I thought thats what this part of the site was for. Robin

Actually, you are going to be accused of being unable to properly respond. I moved your comment from the bottom of the page to this section. --Kainaw (talk) 15:38, 11 April 2006 (UTC)
Those aren't authoriative sources. This Beaty character seems to be a crackpot as well. His page is linked to by crank.net. What else need I say? --BluePlatypus 16:56, 11 April 2006 (UTC)
That's interesting. I know Bill Beaty's site, and I wonder whether crank.net listed him as an "anticrank" or a "crank". Could you give me the context for the link that you found on crank.net, please? I tried the obvious Google searches like "beaty site:crank.net", but without success. I spend a lot of time battling real cranks on Wikipedia, and IMO Bill isn't one of them. --Heron 19:23, 11 April 2006 (UTC)

The answer Robin is looking for can be found in human psychology, not physics. Humans mispercieve things all the time. Humans misreport things all the time. "How would it work?" It doesn't. It can't. Wouldn't it be cool, useful, and a source of immense profit if it existed? Of course it would. The actual profit here lies in selling books and ads on sensationalistic sites. Always follow the money. WAS 4.250 17:37, 11 April 2006 (UTC)

Thank you for a civil reply. Actually if you study the evidence, and arthur c clarke did in his book "world of mysterious powers" not all poltergeists can be put down to misunderstanding, illusion and fraud. Secondly their seems to be many effects that can do things described in some poltergeist cases. I have been told electromagnetic fields, ultra and infra-sound, ionizing radiation,radiation pressure and static charging can shoot things about. But the complete expulsion of the case i mentioned as fraud without a proper incquiry bugs me. It seems like a genuine case. and remember ball lightning was thought to be non-existant by scientists at first but lo and behold http://physicsweb.org/articles/news/10/2/6 , http://www.newscientist.com/article/dn1720.html in fact one of these thinks that poltergeists and them may be completly related natural phenomena. not paranormal or magical or spiritual, just misunderstood. And the only bill beaty articles i can find on crank .net are critisms of over skeptical science, no listing of his site on either science, paranormal, electromagnetism, or antigravity pages which he should be listed under. Robin 22:45 april 11th

I toss this out as speculation. Since the fields where so high and the 2nd guy felt crackling over his skin, maybe the effect was physiological. Maybe the fields where so high they were interfering with the action potentials of his nerve-muscle synapses. He said he couldn't turn around , he had to back out. Lost control of some muscle groups. This could be new information for the biophysics journals, if it were followed up with more testing. --GangofOne 23:30, 12 April 2006 (UTC)

Hmmmm i doubt it was something like that as its gave no mention of loss of muscle control, it states he leant his full weight against the invisible barriar, he coudnt do that if he had lost muscle control. Also have done some research and i think that electromagnetic / static electric and static magnetic fields can produce force to move things, maybe this was a large, stationary static magnetic field? poltergeist explanation aside, i would like to know how this works. Robin 16:37 14th april

Speculating, I see three best possibilities: one with high probability and two with low. As mentioned above, very likely the effect was caused by "electrotetanus" where high-volt pulses of many mA applied to the skin will cause muscles to lock, as mentioned above. Since the original "e-wall" article, a company called "HSV Technologies" developed a similar phenomenon into a beam weapon; essentially a Tazer using UV laser-ionized paths rather than wires. A second possibility is far less likey: that the "e-wall" effect is genuine but was caused by perfectly normal physics, perhaps by small pressure gradients of ion clouds mentioned in the article, or perhaps it's akin to the recently-discovered "hot ice" effect, and is caused by an aerogel of water molecules stabilized by strong e-fields. Very interesting if true! A third possibility: the effect is genuine and is completely outside of current physics. Such events are rare but not unknown, as when Roentgen noticed a glowing chemical on his lab bench, or when Henri Becquerel put a piece of uranium ore against a photographic plate and accidentally founded an entire new field of physics.
But note well, all of this is pure speculation. There are no "answers" here, only unknowns and probabilities. Comments of skeptics aside, nobody can KNOW that it's mere electro-tetanic effect, any more than we can KNOW it's an earthshaking physics discovery. To banish the unknown, we're required to reproduce the original phenomenon and then verify its causes. (The first thing I asked Dave Swenson was whether he tried throwing an object at the "wall." Nope. Too bad, since the result would have told us a lot.) --Wjbeaty 20:23, 14 April 2006 (UTC)

Hmmm thank you for your input mr Beatey, but as i stated above, the acount talked about leaning his whole weight against it, that could not have been done with just a loss of muscle control, and also if this were true he would not haven been able to walk himself out. So we are stuck with the other two, i am more inclined to beleive the idea that it was normal physics, just in an unusal manifestation. But i have a question which is what kinds of electromagnetic [ or purely electric or purely magnetic] fields can have an effect on objects and people, not a wall effect per se, just moving or knocking about by concussive force etc? Robin 00:27 15th april Robin

Eusing Free Registry Cleaner[edit]

Does anybody have experience of using Eusing Registry Cleaner? My registry must be in need of serious cleaning out but I know that tinkering with one's registry is a dangerous activity, so I'd really want to know I can rely on any software that's going to effect it. Casual reviews much appreciated. --bodnotbod 01:25, 11 April 2006 (UTC)

If in doubt, always make a full backup first (open regedit, File -> Export, and make sure to select "All" as "Export range"). Then make small, incremental changes, restarting your computer between changes to ensure it still works. I have no familiarity with the program you mention, but check if it has a backup or undo option - most registry editors do. But, in any and all cases, make backups! :) — QuantumEleven | (talk) 06:16, 11 April 2006 (UTC)
This one looks OK (softpedia give it a clean rating though like Quantum I have no direct experience of it), but you're right to be cautious; the whole malware arms race has led to increasing amounts of malware masquerading as anti-malware tools. --Bth 10:12, 11 April 2006 (UTC)
The software claims to back up for you (or offer a restore point), but I shall follow your backup idea as best practice, thank you. Anyone with direct use of it? Oooh! ALternatively, can anyone recommend a highly regarded open source app for the same sorts of things? --bodnotbod 13:03, 11 April 2006 (UTC)

Constructivist learning theories[edit]

Does anyone know of exmaples of cognitive and social constructivist learning theories? i understand the concepts but need to exmaples to understand them clearly.

There is a very large selection of pedagogies (approached to teaching) that trace their origin to constructivist learning theories. At the base level an approach that uses hands on, discovery learning, can be considered constructivist in origin (students being the architects of their knowledge). There are many sophisticated examples (try doing a google search for constructivist pedagogy). One example I am familiar with is Covis. -Fermion 02:17, 11 April 2006 (UTC)

Yahoo! and computing services[edit]

The first page of the Yahoo! article states that Yahoo! is a "computing services" company. However, the provided link, computing services, seems to be a redirect to outsourcing. I was hoping to learn from the article what Yahoo! does, since I'm under the impression that they "run a website". I assume that the outsourcing link is inaccurate? -- Creidieki 02:29, 11 April 2006 (UTC)

The outsourcing link is accurate. Yahoo! hosts and maintains one of the e-commerce web sites for one of the companies that I work for. So we outsource the work to them. They do this for lots of companies. I'm not real familiar with the company and its services but they do perform at least some outsourcing. Here's the address for that service: http://smallbusiness.yahoo.com/merchant/ Dismas|(talk) 04:17, 11 April 2006 (UTC)
I believe Yahoo! is also an internet service provider and provides it's own search engine. StuRat 22:29, 11 April 2006 (UTC)

Could you contain the current from a lightning strike[edit]

If you ionized the clouds (somehow), would it be possible to store the current from an lightning stike, given the amount of power discharged by them?

Your terminology "store the current" isn't what I think you mean. I think you mean "store the charge". While you could store some charge from a lightning strike, it would be very little of the overall charge. To date, devices that store charge require time to store up a charge. Lightning happens so quickly that there is no time to store much of the charge. However, it may be possible to steal a little charge from the clouds over time. There is a clear difference in charge between the top of tall buildings and the bottom. It isn't a huge amount, but it may be enough to trickle charge a battery. I've often considered doing an experiment with a lead on top of my offfice (13 floors) and a lead on the ground. The problem is that I don't have easy access to the roof and I'm sure someone would get upset if I hung a cable from the roof to the ground. But, you are free to try it. You may be able to do the same with a kite, using insulated wire for the 'string'. --Kainaw (talk) 13:37, 11 April 2006 (UTC)
Sorry, I must object. Flying a kite where there is possibility of lightning strike is potentially lethal. We all know Benjamin Franklin did it and became famous for it, but he was lucky. He was smart enough to know to use a silk thread (a nonconductor) for a distance to the cotton thread that went to the kite. The cotton , when wet, was a conductor, was connected to the famous key. He did NOT hold the cotton thread. He held the silk thread that was tied to the cotton thread, according to what I understand. I recommend some library research before messing with lightning. Trying to store the charge of lightening has been tried and done, by Franklin, but it is not practical. Read all about it first. No point in dying redoing 18th century science experiments. GangofOne 23:35, 11 April 2006 (UTC)

Thanks...and no I won't fry myself.

I did not say "fly a kite in a thunderstorm". I suggested that a kite be used to get an electrical lead off the ground to see if there is enough potential between high altitude and the ground to charge a battery ... when lightning is not present. As for storing the charge, there is much doubt that Franklin performed such an experiment. He flew a kite in the rain (after Thomas d'Alibard did a nearly identical experment with a tall iron rod). Then, there were many failed experiments around the world with lightning rods and jars of various substances. Many house fires followed. --Kainaw (talk) 23:46, 11 April 2006 (UTC)

Linux system keeps setting clock time wrong[edit]

I am running a Fedora Core 3 Linux system with Gnome 2.8. Every time I power up the system, its clock is at the wrong time, it's usually about 40 minutes in the past. I've tried setting the correct time with both date and hwclock but that only helps for the current session, when I reboot the computer the clock is at the wrong time again. Is it some weird service I'm running or is it a bug? I usually have fairly long uptimes, up to over a month, might this have something to do with it? How would I go about diagnosing it? JIP | Talk 06:42, 11 April 2006 (UTC)

Fedora might be synchronising the clock with an NTP time server every bootup. I haven't used Fedora on a day-to-day basis, but quite a few distros seem to do that. Check the ntpd service and if it's starting on bootup. -- Daverocks (talk) 09:07, 11 April 2006 (UTC)
Maybe try the BIOS? - mako 09:14, 11 April 2006 (UTC)
I've had (acutally, have) the same problem. It is caused by hwclock (see man hwclock). On my previous install I fixed it by rm /etc/adjtime, but I think that removing the --adjust parameters when hwclock is loaded should fix it as well. —Ruud 11:01, 11 April 2006 (UTC)

Another possibility is that the hardware clock is bad. They don't last forever. StuRat 22:16, 11 April 2006 (UTC)

But this is a fairly new system. I only bought it fresh from the store, assembled from off-the-shelf parts (new, not used) a year ago. JIP | Talk 15:36, 12 April 2006 (UTC)
The next step in diagnosis is to note exactly in what way it is bad. Is it always shifted by a fixed amount from the correct time? Is it always a particular date, like January 1970? Is there some other pattern? Notinasnaid 18:38, 12 April 2006 (UTC)
It is always shifted by a fixed amount of time (approximately 40 minutes in the past). JIP | Talk 13:27, 13 April 2006 (UTC)
Is ntpd running and if so whats its server list set to? it sounds like you may be syncronising off a bad time server. Plugwash 13:48, 13 April 2006 (UTC)
ntpd was not running. I activated it and set it to connect to ntp1.kolumbus.fi. This fixed my date and time settings. But as for rebooting, I am still not sure, because I use my company's private DNS server, which is only available through a PPTP connection, which is not started at bootup. So I fear that when I reboot the system, ntpd will not be able to find the NTP server, and will just quit, leaving my system back to the incorrect time. JIP | Talk 19:04, 13 April 2006 (UTC)

Timing Diagram[edit]

Hello,

I would like to write an article on Digital Electronics Timing Diagrams.

I have found a stub: wiki/Timing_diagram, but this relates to the new UML 2.0 Timing Diagram.

Where should I start my article.

Regards,

Mark

If there are two clearly different subjects that could fit into a title it can be handled using the diambiguation guidelines. Basically with two articles, you put links up the top of each page, explaining its context, and directing people looking for the other context, to the other page. A likely target for starting your article could be Timing diagram (electronics), as a suggestion. Ansell 09:01, 11 April 2006 (UTC)

UML Aggregation and SQL[edit]

I've been set the task of implementing a database schema given in UML as a MySQL database. In terms of design, what does the composition/aggregation relationship on the UML diagram translate to in terms of the tables required? The specific problem is the classic "library" system - there is a table Book which has the book details, then a relationship to an entity BookCopy, which has only one field listed. Is this extension, or inheritance, or neither? - does the arrow imply a foreign key? There is then another entity with the aggregation symbol - LoanedCopy. Could anyone give any advice on the structure of this, or a pointer to somewhere which has a decent tutorial covering UML -> SQL.

Cheers. QmunkE 12:54, 11 April 2006 (UTC)

It sounds like there would be a one-to-many relationship from the Book table to the BookCopy table. Perhaps each copy has a unique serial number ? In that case that would be the primary key to the BookCopy table. The ISDN would be the primary key in the Book table and also a foreign key column in the BookCopy table. The LoanedCopy table would be similar to the BookCopy table, but would also have info on who checked out the books, when they checked them out, when they returned them, etc. StuRat 22:09, 11 April 2006 (UTC)

Spacetime[edit]

Could anybody popularly explain the concept of four dimensional spacetime?

Time is just a dimension - like depth, width, and height. The best explanation I've heard is the "flatworld" example. Get a piece of paper. Put a penny (or something flat) on it. That is your flat man. He cannot see up and over anything because his world is completely flat. Draw a line on the paper. He can't see over it. It is a wall to him. You can make a box with an opening for a door and call it his house. When he is in his house, he thinke he is boxed in on all sides. But, you know different because you see in three dimensions. You know that you can pick him up and put him outside his house. The little flat man's point of view (lack of being able to see up) is similar to our point of view (inability to see forwards and backwards in time). --Kainaw (talk) 16:14, 11 April 2006 (UTC)
Spacetime GangofOne 23:20, 11 April 2006 (UTC)
Kainaw's example is greatly explored in the book Flatland by Edwin A. Abbott, a book I'd certainly recommend. EWS23 | (Leave me a message!) 01:10, 12 April 2006 (UTC)
Or The Planiverse for a more detailed and mind-blowing view of what life would really be like in 2D space. —Keenan Pepper 04:06, 12 April 2006 (UTC)
The allies of space and time was first perceived by the German mathematician Hermann Minkowski, when he studied his former pupil Einstein's Special Theory of Relativity and realized that their unique connection in behaviour due to the states of motion of the observed objects must be that they are ultimately one thing altogether- space- time, neither one nor the other. This idea was so radical and useful that Einstein incorporated it himself later for inclusion in General Relativity, ten years later. For a better mathematical understanding of the subject, please consult the special introductory page on the Special Relativity page and spacetime. Luthinya 18:32, 12 April 2006 (UTC)

If time is accepted as the fourth dimension, which it apparently is from the above responses, is that the limit of dimensions that "exist" in the universe? Is there speculation on what might be the fifth dimension? Loomis51 23:25, 15 April 2006 (UTC)

String Theory assumes 11 dimensions and others assume more. Check it out. Luthinya 10:04, 17 April 2006 (UTC)

Size exclusion chromatography - De-salting a protein solution[edit]

I am trying to desalt a protein solution using a column of Sephadex G-25. Is there a rule of thumb for how concentrated this protein solution can be? (I know that if the solution is too concentrated, it causes problems) ike9898 17:08, 11 April 2006 (UTC)

Salt concentration or protein concentration? --BluePlatypus 18:29, 11 April 2006 (UTC)
Protein concentration. ike9898 20:51, 11 April 2006 (UTC)
Well, it all depends on the flow, eluent, the protein itself, etc. But 25 mg/ml seems to be the maximum recommended[20]. --BluePlatypus 21:42, 11 April 2006 (UTC)

If you have a concentrated, salty protein solution the best desalting choice might be dialysis. Simply put the solution inside some moistened dialysis tubing and place the whole thing into a low salt buffer, which you can replenish as necessary. You can leave it overnight or longer. The dialysis membrane traps the protein inside while the tiny salt ions will diffuse through the membrane into the low salt solution by osmosis. This is a routine technique in protein prep.

Another option may be using a centrifugation based device. This allows you to desalt and concentrate the protein in a single step. Refer to the manufacturer for more details (e.g. Centricon).

Size exclusion chromatography is a good technique for purifying one protein from a mixture of proteins and is seperates based on molecular weight. As in all chromatography, the amount you load on this column depends on how big the column is. The bigger the column, the more you can load. Refer to the manufacturer's instructions for your particular brand of packing for the recommended loading amount.

I'm desalting a protease and I get autolysis if I dialyse. SEC is very quick, and easy to set up in a cold room. But, my protein peak is spreading WAY too much. I thought it might be due to too high a protein conc (increasing viscosity). This technique should be routine, but it is new to me and it's giving me a royal pain! ike9898 17:55, 12 April 2006 (UTC)

LG L1515S monitor[edit]

I use a LG LCD monitor LG L1515S. Is it a low end, low quality monitor? This is the cheapest LCD monitor which I saw and I thought it does not matter to buy the cheapest monitor? Is there any problem buying cheap LCD? whats the problem? Comparing cheapest LCDs and mid/high quality CRTs, which is better?

LCDs tend to be dim, only give a good quality pic when viewed straight on (not at an angle), and occasionally have a few pixels which are some random color. CRTs don't have these probs, but might be harmful to your eyes, can be blurry, tend to be rather heavy, and may not last as long. A plasma screen display is the best of all, but most expensive, too. You should look at the max resolution (1280x1024, for example), screen size (15 inches, for example), and the refresh rate (60Hz, for example) to evaluate a monitor. Ideally, they should all be as high as possible. Note that the refresh rate often varies with the current resolution setting. A low refresh rate will make the screen appear to flicker, especially when a white screen is displayed. A low resolution will make it difficult to display much on the screen at once and a small screen will make you need to squint to see anything. StuRat 21:50, 11 April 2006 (UTC)
Refresh rates aren't really relevant to LCD monitors. One thing that does matter with LCDs is response times: the lower, the better. If you want to play videos or games, 8 ms (milliseconds) is great, and anything under 16 ms is good. In this day and age, the benefits of LCDs generally outweigh the benefits of CRTs: in fact, most places barely sell CRT monitors any more. Sum0 15:22, 13 April 2006 (UTC)
Also with lcds you have to be quite carefull about the resoloution. Higher ≠ better Windows at least (i can't speak for linux or mac) pretty much relies on changing resoloution to change the displayed size of text (there is a font size setting but the user interfaces or lots of app break if you dare change it). Running an LCD at any resolotion other than an exact fraction of its native means a blurry display that gets very hard on the eyes.
This means several things
  • you must be happy with the size of things on your normal desktop at your lcds native resoloution
  • if you run games you must be happy with them on your screen, lukilly games tend to use much bigger text than productivity apps so the blurring isn't such an issue but it still helps if you are happy with your games at the native resoloution or a fraction therof (happy with includes both framerate and detail, normally you balance theese by adjusting resolotion but LCDs put you in something of a straightjacket).
  • If your vision deteriorates (or if an older relative wants to use your computer) you can't just lower the resoloution to compensate.
All in all this adds up to a lot of lost flexibility when moving from crt to lcd Plugwash 00:18, 14 April 2006 (UTC)

Call termination charge in USA[edit]

Is there call termination charge in USA? In India, telecom companies from which calls originate pay a call termination charge of Rs.0.30 to the network in which the call terminates. Is there any call termination charge in USA? If yes, what is the call temination rates? How come companies offer unlimited calling to other companies's phones when there is a termination charge which metres by the minute?

The US telecom industry places all sorts of goofy charges and surcharges on telephone calls. While our article doesn't enumerate many, the FCC has a sample phone bill complete with charges and explanations for a typical US monthly phone bill. As for termination charges specifically, I think that varies by plan. As I recall, such charges may exist but are frequently handled by a long-distance provider who then provides the end-user with a flat per-minute rate. — Lomn Talk 19:46, 11 April 2006 (UTC)

Difference between Google news & topix.net[edit]

What is the difference between topix.net and Google news? Both seem to aggregate news. But topix.net serves ads and no one minds while there has been lawsuits against Google news and it is not able to serve ads. Whats the reason and whats the difference between these two?

First, money. Google is a cash cow for lawyers to sue. Second, methodology. Google searches anyone they like and they post results of their search. News sites have to partner with Topix (see their 'about us' page for info on the types of partnerships they have). --Kainaw (talk) 23:58, 11 April 2006 (UTC)

A medical query?[edit]

Taking my place at the urinal this afternoon, I was joined by my newest coworker setting up shop at the adjacent recepticle. Somewhat contrary to my own restroom M.O., he asked how I was doing, and out of politeness I returned the question. However, despite the divider between the urinals (which really ought to be law), I was struck by that phenomenon commonly known as "stage fright." That is, even though I had a full bladder on (in) my hands, I was incapable of micturating until immediately after he left. Why/how does this occur?

The bladder is controlled by the autonomic nervous system. Parasympathetic neurons innervate the wall of the bladder (the detrusor muscle, trigone and sphincter). Parasympathetic stimulation results in contraction of the bladder muscle and relaxation of the urinary sphincter resulting in urination. This is opposed by the sympathetic division of the autonomic nervous system.
Anxiety or fear, including social anxiety, results in decreased parasympathetic stimulation and increased sympathetic stimulation of the bladder, resulting in relaxation of the bladder proper and tightening of the urinary sphincter, making it more difficult to pee. There's always the stall. - Nunh-huh 18:47, 11 April 2006 (UTC)
There is an article covering this: Paruresis --Ed (Edgar181) 20:34, 11 April 2006 (UTC)

I believe this is an evolutionary adaptation. That is, urinating or defecating in the presence of a stranger (or someone you don't fully trust) is a bad idea, as it leaves you vulnerable to attack. Thus, humans (and other animals) tend to delay elimination until they feel safe to do so. I suggest you use a stall, instead. StuRat 21:37, 11 April 2006 (UTC)

Indeed this phenomenon is contrary to the popular train of thought: that fright causes urination. As noted above, in humans, a sympathetic response to a stimulus will basically keep you from urinating, it is when you get to a safe place and the sympathetic stimulus stops that you will urinate (in a situation where your body decides you are safe again, although you still may be "scared") often uncontrollably. This reaction is actually a situation rather specific to humans: in canines, for example, sympathetic stimulation will usually cause urination when the bladder is anything but empty. Tuckerekcut 01:20, 12 April 2006 (UTC)

I believe in dogs, urinating on themselves is used as a sign of submission. StuRat 03:49, 12 April 2006 (UTC)
Urination is construed as such by other dogs, and rightly so. if a dog is scared, the sympathetic nervous system is activated, which causes urination. Thus fear causes submission. That this cascade is not under voluntary control is not particularly unusual.Tuckerekcut 03:25, 14 April 2006 (UTC)

There is also another possible explanation for this, which you may find slightly disturbing (but you shouldn't, it's quite natural). I was once at a fully packed pub where there was a lineup for the ladies' room but not the men's (as is so often the case), but this time the girls decided what the hell and started to use the men's room. There was no divider between urinals, and they were the type where the drain is at the bottom, so basically you're urinating against a wall. In any case, being out in the open (literally!) in front of all those female strangers was, to be polite, somewhat titilating. It also had the result of making it impossible to urinate. The medical explanation for this is simple: when aroused, the bladder is completely cut off from the urethra, and its impossible to urinate. (You guys know what I mean!). It's also common for heterosexual men to become involuntarally aroused in certain situations. Bottom line: Even if you're totally straight, the fact that your genitals are hanging out of your pants in the presence of another person (in this case, a male) can lead to difficulty in urinating. Loomis51 23:50, 15 April 2006 (UTC)

benefits of organic foods for immunno-compromised individuals...[edit]

I would like to know what the benefits are, if any, of organic foods are for immuno-compromised individuals, those with HIV/Hep C in particular. Thank you.

---BR.

I'm not sure that they are. You may want to check out our article on organic food. The crux of your question revolves around how organic foods differ from ordinary foods, which itself is the center of a firestorm of debate. However, the article does mention that organic foods grown in manure actually increase the risk of contamination with E. coli and other bacteria, which is not a benefit at all. Isopropyl 19:29, 11 April 2006 (UTC)
No body knows. No rigorous research has been done on this. Some doctors believe that there may be benfits, but it's highly controversial. For great justice. 01:23, 13 April 2006 (UTC)
There was some research in the UK last year sometime which found that there was no scientifically identifiable benefit in earing organic fruit & vegetables. AllanHainey 10:01, 13 April 2006 (UTC)

computer repair?[edit]

what is the best way to fix up an old computer?Cooliabeanias 19:26, 11 April 2006 (UTC)

Using old computers to run Linux is always a good choice. It runs well even with limited resources, and you can learn to use it on an expendable machine. Isopropyl 19:29, 11 April 2006 (UTC)
If you are technical enough to figure out what type of power supply and memory you have, you can look into getting an upgraded motherboard and CPU that will use the same power supply and memory. You'll benefit from extra CPU speed with little investment. The common mistake is to buy the motherboard first - then finding out that you need to buy a new power supply and new memory because the old stuff is incompatable. Then, the cost is so much that you could have bought a new computer. --Kainaw (talk) 19:53, 11 April 2006 (UTC)
Many "old" but workable computers get put out with the trash. It is possible to get quite usable parts from such machines. Power supplies, drives, cases, sound cards. Sometimes the machine works perfectly, just is old. This is a wasted opportunity, when so many people, mostly kids, could learn a lot from having such a machine. Out of date for the lastest stuff perhaps, but plenty good for learning. If you can put together such machines, you can just give them away, if nothing else. GangofOne 23:15, 11 April 2006 (UTC)
I've tried to give away old "refurbished" computers for email/web browsing. It is difficult. Beggers quickly become choosers. I set up four computers at the homeless shelter with a 5th providing a shared dial-up connection. The problem was that the shelter didn't want to provide a line for dial-up. So, they just became machines for playing solitaire (which was easier to do with the many decks of free cards laying around). Also - on a distantly related topic - I was with a professor doing a talk on Beowulf Clusters. A reporter at the conference asked if these clusters will make use of all the old computers out ther. The professor's response was memorable: "Sure, if you want a huge power hungry heat box with nearly as much processing speed as a standard home PC." --Kainaw (talk) 23:38, 11 April 2006 (UTC)
There are charities exporting refurbished computers to developing countries (see eg here). But I can't help wondering whether the economics of this really work, given that most new computers are manufactured closer to the people being sent the old ones ... (And the "it reuses them which is better than the environmentally-unfriendly components getting junked" argument has to be balanced against the fuel used, surely.)
The only really practical use I can think of for old boxes is as middleboxes if you're running a small LAN off a shared broadband connection or something. --Bth 10:29, 13 April 2006 (UTC)

Chemicals[edit]

how do chemicals reacted in diffrent ways when mixed together thanks alot tomas

They react in a predictable fashion depending upon their chemical properties, hope this helps.
Well, if there was an easy answer to that question, there wouldn't be much need for chemists, would there? :) --BluePlatypus 21:31, 11 April 2006 (UTC)

Library Classification of books[edit]

I have the responsibility of classifying our monastery library. I have been able to find a conversion of Library of Congress numbers with the Dewey Decimal numbers for an annual fee of over $300. Out of the question for such a small library. Is there a conversion table or some kind of rule of thumb that would help quicken the process? I have not been too successful wiht an internet search.--216.129.236.59 19:44, 11 April 2006 (UTC)

Is the Poor Clares Monastery in Great Falls? How large a library do you have? Does the existing library have Dewey call numbers, and you want to switch over to Library of Congress? If so, and if the library is not too large, would it be useful to use the LOC website to look up the books and obtain the LOC call number? Some of the external references in the linked articles may help. - Nunh-huh 20:18, 11 April 2006 (UTC) You may also want to consider joining the "Project:Wombat" mailing list, where a lot of librarians hang out, and ask this question there. - Nunh-huh 00:31, 12 April 2006 (UTC)
I have an old book called Dewey Decimal Classification and Relative Index - published by Forest Press Inc, Lake Placid, NY. My copy is dated 1959, so whether it's still being printed or not I have no idea. Unfortunately, given its age, it has no ISBN (ironically it has a LoC Call number - 59-11569). It is designed for libraries and provides a list of all the dewey classifications both alphabetically by subject and numerically by code. Understandably, given its age, it has certainly been considerably revised since then (where would you file books on DVD recording, OCR, or even digital watches?), but if it's still out there it might be exactly what you need. Grutness...wha? 02:36, 12 April 2006 (UTC) uhh. skip that - I misread the question. Grutness...wha? 02:42, 12 April 2006 (UTC)

I am familiar with the Forest Press book. I used it in school eons ago. I don't need a detailed list as we are going with a modified Dewey Decimal classification. And, good heavens, Nunh-huh, why would you come up with Great Falls Montana and specifically a Poor Clare Monastery at that? Isn't that a little obscure and wild? Our books are unclassified at this point. So I am starting from scratch. 12:22, 12 April 2006 (UTC)

Your IP address (216.129.236.59) is listed as being in Great Falls, MT. --Kainaw (talk) 13:24, 12 April 2006 (UTC)
I found this site which gives the Dewey classification if you enter the ISBN. If you can get your hands on a bar-code scanner (maybe an old CueCat somewhere?), there seem to be several free utilities around to help in creating a catalog. --LarryMac 15:09, 12 April 2006 (UTC)
Not much help for any book published before 1970, though... Shimgray | talk | 15:29, 12 April 2006 (UTC)
Speaking as a cataloguer for a small-medium library, we use DDC20 at work - it's two decades old, but as long as you're willing to be creative with some sections (we have a heading which technically parses as "21st century history of the Soviet Union"!) that's not much of a problem. Anyway, the point there is that older editions of Dewey work fine, and if you try asking around it's quite possible a larger library (or library school) still has the old cataloguing manuals gathering dust on a shelf somewhere after they went to a more modern version - they're not much use after you've changed, except for training purposes, so asking nicely might well just get them as a donation.
Of course, real classifying might be more effort than you want... if all you need is a very simple "high-level" classification, OCLC do publish a list of the "thousand sections", the top-level sections of Dewey (PDF), which should give you a baseline to be going on with. For individual books, you could try running them through the Library of Congress online catalogue - they have Dewey numbers listed for most of their stock - but it's probably just as quick to give them a general classification yourself once you have the hang of it. Shimgray | talk | 15:28, 12 April 2006 (UTC)

Thank you, for all your help. With the information provided I was able to find just what I needed. Shimgray's link to OCLC.org I was able to find the summary. Now I will be able to keep our classification consistant and heave others help me do the cataloging. We want the library to be extra user friendly and so we are using a modified DDC. I checked with all our PC monasteries on-line and culled the best possible classification system for our smaller libraries whcih ae also over loaded in the 200's. And, yes, I am at the Poor Clare Monastery in Great Falls, Nunh-huh. I would like to go back and do some adding to the Poor Ladies entry as it is bare bones information. It will have to wait a while as I have my hand full right now.Judith 20:26, 12 April 2006 (UTC)

Sounds good, and glad you got to a solution. Have a good time organizing, and we await any contributions to the Poor Clare article with patient antici-----pation! (It really is a little pitiful!) - Nunh-huh 23:34, 12 April 2006 (UTC)
I suppose it depends on how many books you have but I always prefer a more idiosyncratic filing system - largest to smallest, left to right. It makes it more fun looking for something & increases the chance of finding something you never knew you were looking for.AllanHainey 10:04, 13 April 2006 (UTC)

Gasoline and styrofoam[edit]

I've always been told that styrofoam will dissolve in gasoline and therefore you shouldn't store one in the other. Does this happen? And if so, why? Dismas|(talk) 22:17, 11 April 2006 (UTC)

Yes, gasoline does dissolve styrofoam; I know because I once tried to fashon a funnel from a styrofoam cup, to help get gas into my moped. Gasoline is a non-polar solvent, and it is good at dissolving other non-polar materials, including stryofoam. Some synthetic polymers are much more resistant to this than others. ike9898 22:21, 11 April 2006 (UTC)
Gasoline is a good solvent. Some idiots apparently use it in the washing machine to clean grease off their clothes, and then get a nice explosion when they put the clothes in the dryer. (The clothes may not have any oil stains, but you will need to pick them out of the debris to find out.) StuRat 22:34, 11 April 2006 (UTC)
Styrofoam melts easily in any number of solvents, including gasoline, turpentine, paint thinners, etc.. It can also sometimes melt from lemon juice. Ande B 00:48, 12 April 2006 (UTC)
Dissolving styrofoam and soap in gasoline is a good cheap way to jellify it, creating a napalm. :) -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 04:29, 12 April 2006 (UTC)
Thanks for the replies, everyone. I'm sure the gasoline that those people use in their washing machines does wonders for their septic systems if they happen to be on one.  :-) Dismas|(talk) 10:29, 12 April 2006 (UTC)

Coyote/dog hybrids[edit]

I overheard a man at the pet store the other day say that his dog is half coyote. Are Dog/Coyote hybrids fertile? User:Zoe|(talk) 23:01, 11 April 2006 (UTC)

I guess Coydog answers my question. User:Zoe|(talk) 23:04, 11 April 2006 (UTC)

April 12[edit]

Gettin' burnt...[edit]

i accidentally burnt my finger yesterday with an iron, and little watery poxes appear on my finger, why's that? Thx --203.218.93.206 01:08, 12 April 2006 (UTC)

I'll take blisters for $400, Alex. - Nunh-huh 01:09, 12 April 2006 (UTC)
You can check out Burn (injury) as well for more information about burns. Ansell 01:11, 12 April 2006 (UTC)
You have a second-degree burn. (Please leave your OHIP number on my userpage.) - Cybergoth 04:22, 13 April 2006 (UTC)

Need Help on an Article[edit]

Can I get some help with checking the information on the Boiling Constants page and also setting up the data into tables? Ctifumdope 01:33, 12 April 2006 (UTC)

One comment, the Wikipedia naming convention is to only capitalize the first word in an article name, and make it singular, so you should rename the article accordingly to Boiling constant. StuRat 03:43, 12 April 2006 (UTC)
Help:Table is a good page that can help you with formatting your information into tables. -- Daverocks (talk) 04:35, 12 April 2006 (UTC)
I moved the page to List of boiling constants of solvents. -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 05:40, 12 April 2006 (UTC)

Sound and Balloons.[edit]

hi, i would like to know why and how does a exploding balloon produce sound? thankyou —Preceding unsigned comment added by 202.138.102.141 (talkcontribs)

Sound waves in air are composed of alternating pressure differences. The pressure inside a balloon is higher than outside (or it wouldn't be inflated in the first place). When you prick it, the pressure equalises; because the speed of propagation of pressure differences isn't infinite (it is, of course, the speed of sound), this doesn't happen instantaneously -- an expanding sphere of high pressure radiates out from the balloon, which you hear as a bang when it reaches your ear. --Bth 09:46, 12 April 2006 (UTC)

I was interested in this question, since the process is somewhat identical to earthquakes. Here is a good reference: [[21]] It has nothing to do with the air, but the speed of the fracture propagation, and the whip of the fragmented ends. These form mini sonic booms. You can experiment by interferring with the latex (tape) and showing how it muffles the sound. You can do different things to get a really loud pop. --Zeizmic 14:30, 12 April 2006 (UTC)

ElectroMagnetic Disturbance[edit]

How is it that a nuclear explosion creates an elecromagnetic pulse?How does this harm modern IC's only when they are in use?

See electromagnetic bomb for the processes involved and how they interfere with electronics. But where do you get the idea that ICs are only vulnerable when in use? Unless they're shielded (by being put in some sort of Faraday cage) they're going to be vulnerable on or off. --Bth 10:56, 12 April 2006 (UTC)

Computing Data Storage DVD[edit]

What is the difference between a DVD-RW DVD-R and DVD+RW DVD+r?

"R"s can be written to once, then the data's fixed; "RW"s are rewritable (with full erasure first for the -, random access for the +). The +/- thing is a standards mismatch between different manufacturers (like VHS/Betamax for video formats, except that we're still at the stage where the marketplace hasn't chosen a standard). Various arguments are advanced in favour of the two; you can read more at the articles in question. --Bth 10:45, 12 April 2006 (UTC)

Altitude and temperature[edit]

Why does it become cooler as we go higher?As we are nearing sun i suppose it should get hotter.-explain

Erm, no. For one thing, the heat from the Sun reaches the Earth as radiation, much of which passes through the atmosphere and heats up the ground, but the overall siutation is complicated --there are layers where temperature increases with altitude, but the processes involved are more involved than just "it's nearer the sun". See Earth's atmosphere for more. --Bth 10:35, 12 April 2006 (UTC)
The higher you go the thinner the atmosphere is, which means fewer particles to transfer the sun's radiation (or heat absorbed from surroundings) to you. Also with more room to move the particles are less energetic. Higher pressure = hotter. Lower pressure = cooler.--Anchoress 11:08, 12 April 2006 (UTC)
However, in the thermosphere the temperature is controlled by the absorption of solar radiation and the temperatures can get as high as 2000oC. So there the questioner's original assumptions do sort of hold. --Bth 11:11, 12 April 2006 (UTC)
It's still entirely irrelevant that you're closer to the sun. The difference in solar radiation intensity between the ground and the top of the thermosphere (using 690km) is 9.2\times10^{-6}, which is hardly important. It is true that some high-energy radiation is available there for heating that isn't available on the ground, but it's more like the rest of the atmosphere is in the thermosphere's shadow, rather than that the thermosphere is appreciably physically closer to anything. --Tardis 17:11, 12 April 2006 (UTC)
Unfortunately your idea happens to be the common misconception. It is totally irrelevant here, as Tardis has said, whether you are close to the sun or not. The fact is that as you go up higher, the atmospheric pressure drops considerably, and with fewer air particles to transmit the sun's radiation or generate energy between themselves by bumping into each other, naturally the air temperature drops. I suppose your closer distance does mean that you would expect to feel the heat of its radiation more strongly, but even without the effects of the atmospheric pressure as I have described, considering the vast cosmic distances between the sun and the earth, even a mountaineer standing at the top of Everest will not be able to feel all that much difference to when he was upon sea- level itself. Luthinya 18:39, 12 April 2006 (UTC)

Vectors in EMW[edit]

Is there an easier practical illustration of the common terms we use in Electromagnetic Theory like Gradient,Curl,Divergence?

Which illustrations are you already familiar with? In general, they're slightly fiddly to get across in non-mathematical form, hence the amount of handwaving that generally goes on, but they work wonderfully once you get your head round the del operator.
Having said which, Feynman probably handles them wonderfully in Volume II of the Lectures on Physics; I'll look it up tonight when I get home. --Bth 10:40, 12 April 2006 (UTC)
In fact, Feynman pretty much takes the same delaying the physical meaning until you've grasped the maths approach that I was suggesting. Rather surprising. --Bth 10:22, 13 April 2006 (UTC)

Marine Engineering[edit]

How is it possible to maintain a watertight seal between the rotating propeller shaft and the hull in a submarine or ship keeping in mind the intense water pressures the submarine will face when submerged?

I'm sure this question's been asked before, but I can't find it ... --Bth 11:08, 12 April 2006 (UTC)

Stuffing box --Zeizmic 11:45, 12 April 2006 (UTC)

calcium / sugar[edit]

Is it oxalic acid, made from calcium?, that the body uses to digest sugar?? not sure if i spelling right.

m

Oxalic acid is two COOH groups bolted onto each other; it contains no calcium. Enzymes are what break foods down in digestion -- for the specifics of the digestion of sugar, see glycolysis and for what happens after that, Krebs cycle. Calcium is important in the body as a constituent of bones and teeth. --Bth 12:48, 12 April 2006 (UTC)
As a note Calcium is involved in Muscle contraction and is involved in carrying the eletrical charge down a Neuron in the Electrical synapse. Wish I had better sources for the neuron thing as it's been 9 years since my animal physiology course.--Tollwutig 13:30, 12 April 2006 (UTC)
Oxaloacetic acid is an intermediate in the breakdown of most sugars, yes. Neuronal transmission is mostly the affair of sodium and potassium. Physchim62 (talk) 13:41, 12 April 2006 (UTC)
Though calcium is involved in transmission across chemical synapses, by triggering the release of neurotransmitter vesicles. I'm guessing calcium has only a small role in typical electrical synapses because the intracellular concentration of calcium is so low in most cells. --David Iberri (talk) 22:03, 12 April 2006 (UTC)
And, yet, if the concentration of calcium ions in the extracellular fluid drops, it produces excessive and painful muscle contractions called hypocalcemic tetany. The concentration may be low, but Ca is certainly not unimportant to neurmuscular transmission. alteripse 00:43, 13 April 2006 (UTC)

MIME[edit]

Can you please explain what a "MIME TYPE" is?and can you list a few MIME types?

We have a good article on MIME. MIME helps identify what the type of content that is being sent is. Some examples are: text/plain, text/html, image/jpg (I think). -- Daverocks (talk) 12:42, 12 April 2006 (UTC)
IIRC the last one should be image/jpeg. --cesarb 19:18, 12 April 2006 (UTC)

Time series analysis[edit]

The linear regression model can be used to estimate expected value. When applied to a time series, linear regression may not be useful because it is time-neutral. If I have a scatter chart of a time series, what kind of statistics tool should I use, if I want to:

  • Estimate a rope's possibility of breaking over time. The rope is under a significant load, the fibers of the rope could break any minute. So the strength of the rope may suddently decrease over time. To estimate the possibility of breaking at t0, we may forget about past values. Let's say we have a lab and 1000 such ropes and loads.
  • Estimate a rich person's tendency to buy gifts over time. Suppose the man is influenced by his ever-changing mood. If he's very happy, he can be buying gifts all the time. We don't know if he's happy at any given moment, but we can increase the weight of t0±Δ to emphasize the influence of his mood.
  • Estimate a person's tendency to invest over time. Suppose all that person has is a stock ticker. At the time of decision making, he/she only has past performance. -- Toytoy 12:40, 12 April 2006 (UTC)
Did you come up with those examples yourself? 'Cos they sound awfully like homework ... --Bth 13:02, 12 April 2006 (UTC)
Yes, that's homework. And I am my own teacher. @#$% I should have taken some statistics while I was in college but I did not. -- Toytoy 13:13, 12 April 2006 (UTC)
I'm not sure how a linear regression is relevant here. In the rope example, it sounds like you're trying to statistically describe the lifetimes of ropes under stress. That's just one-dimensional data: a vector of times. You'd just be using standard things like mean, variance, and skewness to analyze that. The other two examples don't have a clear goal to me... if you have data like "on December 11, Roger bought 2 gifts" and "on December 12, Roger bought 0 gifts", all you can usefully do is find times that seem interesting and posit that important events happened then. If you additionally had "on the evening of December 11, Roger's pet mouse caught the flu", then you might want to compute some sort of correlation between the two sets of data. With appropriate quantification of everything and some luck, you might be able to come up with a reasonable model (d^2\mbox{gifts}/dt^2=k(\mbox{good news density}) or something), and then you could do predictions of one variable (gifts or good news) from the other. But when, say, you were trying to calibrate k, you'll just want to use regular statistics, since your model exists outside of time and does not need to be causal. If you do do past-only analysis, it's typically as simple as truncating your data to whatever point in time, fitting some sort of curve to it in the usual ways, then extrapolating beyond it. --Tardis 17:24, 12 April 2006 (UTC)

This is just a shot in the dark as I'm not sure I understand your question fully, but have you considered multiple regression analysis with time being the third variable? It's available on excel. Sorry if this makes no sense, it's been a while since I took stats. Loomis51 00:01, 16 April 2006 (UTC)

A problem about Live Linux CD.[edit]

Hi, just recently i got a softwares dvd, in which Tablix Live Linux CD's ".iso" file was supposed to be there. but actually it was a ".rar" file. so i extracted the whole "rar" file, and then "burned" all the extracted files onto a CD. i am using windowsXP. then i tried to run "tablix" from that cd by making default boot from cd drive, but it didnt work. after that i ran the cd on winXP, even then it didnt start, actually a ".html" file about "tablix" from the cd did start on autorunning, but the OS wouldnt start. now how to do it? even on their website they have not mentioned how to install and use it for windows user. Similarly, on the same DVD, there is an "image" of Cluster Knoppix, but when i see that file's properties, it doesnt show it to be an "iso" file. i tried to burn that knoppix image on to a cd, by using nero 7, but it showed the message that unrecongnisable format, and so i didnt go further. so wats all this going on ? i am a windows user, and if a normal user like me has to go through so much hassles for just trying Linux, is it serving good to the open source community? not at all. so could you please recommend some Live CD OS which can work directly without such hassles. Also , can u tell me any website or organisation , which could send me these Live Linux CD's or other free Linux CD stuff to me. i am from india, and internet speed at my home is not too great, and also too expensive for me to download the ".iso" files of around 600mb size. so if u could recommend some sites which would do so and send me the CD's in india at my place? thank you.

If you have WinRAR installed on Windows, it makes itself the default application to open ".iso" files. This could possibly be why you think it's a rar file, because WinRAR likes to open iso images. If you're right, though, and the images are really ".rar" files, it would probably be better to put all the extracted files into an iso of its own, rather than burning all the files manually. Also, when you say you tried to run Tablix and it "didn't work", does that mean that Windows started booting and the CD didn't? More details would be appreciated. Also, if you tried to get Nero 7 to burn an image file and it said "unrecognisable format", then what you're trying to burn definitely isn't an ISO. What format is that image in? -- Daverocks (talk) 12:51, 12 April 2006 (UTC)
More generally, you could try Linux India (that's the WP article, this is their site) or one of their affilliated LUGs (Linux User Groups) for help getting started with Linux -- it seems to be a large part of their mission to help newbies. And if you don't manage to solve your problems, apparently thanks to LI's activities, sites like this one now sell distros on cheap CD to India. --Bth 13:01, 12 April 2006 (UTC)
I think Ubuntu linux will still mail you free cd's. They send a live CD and an installation CD. And your problems seem to have to do with the configuration of your Windows system, not the linux distrobutions themselves. But I agree getting in touch with the local linux groups would be good, as you'll have lots of things that will be much easier if you have someone to help you with. - Taxman Talk 17:48, 12 April 2006 (UTC)
Have you set your bios to boot from cd? For great justice. 01:15, 13 April 2006 (UTC)
He noted that "i tried to run "tablix" from that cd by making default boot from cd drive". Still, maybe he didn't try to set the order through BIOS. -- Daverocks (talk) 04:02, 13 April 2006 (UTC)
Yeah, sorry, I missed that! For great justice. 15:55, 14 April 2006 (UTC)

Why are adults less able than children to tolerate dizziness?[edit]

Most kids could spin in circles for a minute or more with only mild nausea that quickly passes. Many or most adults would feel ill to the point of vomiting from such motion, and are probably more likely to get nauseous from a simple thing like swinging. Why are children generally better able to handle getting dizzy? --Jonathan Kovaciny 12:49, 12 April 2006 (UTC)

Your assumption does not sound correct to me. People that are highly active can handle motion better than people who rarely move. Children spin, tumble, and run around more than adults. So, a higher percentage of children have a tolerance for that action. Adults who continue to spin, tumble, and run around maintain the tolerance. Also, children who spend all their time sitting in front of the tv do not have a tolerance for motion. --Kainaw (talk) 13:11, 12 April 2006 (UTC)
I certainly can't go on as many roller-coasters as a twelve-year-old. DJ Clayworth 03:34, 15 April 2006 (UTC)

Need to buy a 'surge protector'[edit]

1:24 PM 4/12/2006 DST Need to buy a 'surge protector'

Hi all, I need to buy a 'surge protector' or I think an 'automatic voltage stabilizer' for my home computer as power cuts are becoming more

frequent. The budget is low and i don't think I need anything as fancy as a Uninterruptible Power Supply; just a Plain Old stabilizer is sufficient? I

don't know much about the impact of a hot boot on the devices in my Willamette processor or the 1.5 GHz board. All I know is there might be some

damage to the hard disk with repeated incidents of power failures. Is there anything I am missing? Thanks for your care and dedication. I have been reading this page for quite some time now and I CTRL+D ed it on my firefox. Yours truly, -- Kushal one 17:38, 12 April 2006 (UTC)

A surge protector is no use at all in a power cut. It is designed to protect against sudden increases in power ("surges"). In a power cut, the computer switches off, unless you have an Uninterruptible Power Supply. Notinasnaid 18:34, 12 April 2006 (UTC)

Don't know what a stabilizer is, but you need some form of Uninterruptible power supply --Zeizmic 19:55, 12 April 2006 (UTC)

A UPS can act as a stabilizer, in that it will maintain a steady voltage in the event of power sags or power surges. A surge protector alone might help in eliminating any surge that occurs as power is restored after a power cut. --205.143.37.68 21:25, 12 April 2006 (UTC)
I think there is a difference between a 'surge' protector and a 'spike' protector. I am not sure if that is relevant to what is being discussed here, but here goes what I think is the difference. A 'surge' protector is for things like electric motors which will overheat if too much current is pushed through them, often they have circuit breakers to protect against that. A 'spike' protector protects against brief overvoltages which often occur when powerlines are near a lightning strike, these are very hard on electronics and can cause progrsssive failure because each spike does some damage to the components.
Yes. If you are living somewhere with frequent power cuts, you likely have spikes and surges too. Get a UPS. If you can't afford one, a surge protector will help reduce damage from too much electricity, but won't help with not enough. For great justice. 01:08, 13 April 2006 (UTC)

Thanks all of you. I will need to look for a spike protector then? FGJ (if I call you that), I don't think I can afford a UPS but I will look into the prices for it too. My second question stands. I don't know much about the impact of a hot boot on the devices in my Willamette processor or the 1.5 GHz board. All I know is there might be some damage to the hard disk with repeated incidents of power failures. Is there anything I am missing? Sorry for the added trouble.

The colour of water[edit]

I recall reading once a upon a time that the colour white corresponds to the highest frequency point on the Sun's black body curve (somewhere around 6000K). This is not coincidence, but an evolutionary adaptation. Rather than saying "sunlight is white at its brightest" it is probably more accurate to say "our manner of perceiving white has been conditioned by the sun." An animal around a red dwarf might perceive our red as white and our white perhaps might be invisible in the manner of x-rays etc. OK, if that's utterly out to lunch somebody tell me.

So this got me thinking about water the other day. Again, it's obviously not coincidence that our main biotic solvent happens to be transparent. Would it be fair to say "our manner of perceiving transparency has been conditioned by water"? Another hypothetical alien basking in liquid ammonia might view H2O as an opaque poison? Any formula that describes this sort of thing? I suppose the evolutionary mechanism would be "the clearer the water the safer the drinking." Marskell 17:50, 12 April 2006 (UTC)

As I understand (part of) your question, you are asking if, given different conditions during our evolution, we could ahve evolved in a way that water was not transparent to us, but something else (that is opaque to us) might be transparent to these alterative people. Water is transparent becuase it absorbs little radiation from the 'visible' portion of the spectrum. The radiation absorbed by water wouldn't change, but we could have evolved so that our eyes were attuned to a different part of the spectrum. I believe water is fairly opaque in the UV, so if our eyes saw UV, water would indeed be opaque as well. As to whether there is some solvent that is opaque in the visible but transparent on UV or infrared, there probably is, msaybe someone could provide an example? Chapuisat 18:41, 12 April 2006 (UTC)
"the colour white corresponds to the highest frequency point on the Sun's black body curve", better to say, not highest frequency, but rather , most abundant. Which is maybe what you mean. Yes, it is natural that we are sensitive to the light frequencies that are most copious in penetrating the atmosphere. To be otherwise would be a missed opportunity. But it doesn't apply to transparency. What is transparent to light is physically determined couldn't be changed subjectively in the viewer. Anyway, why would it matter if water where opaque? What if water were silvery like mercury, why would that matter? Except for minor adjustments, like not diving into water without testing depth etc? I don't see why life couldn't evolve if that where the case. (Water in the eyes, would be a problem; probably a workaround) GangofOne 23:08, 12 April 2006 (UTC)
Transparency could be changed if we are talking about seeing with a radically different spectrum of "visible light". For example, if infrared was all we could see, we would perceive some things as being transparent which are not transparent to the radiation we call "visible light", and we would perceive some things as opaque which are currently transparent. Transparency is not quite the same sort of thing as color perception but it is not radically far off. But the "color of water" bit is misleading in this regard, I think. --Fastfission 00:02, 13 April 2006 (UTC)
"Highest" --> "most abundant", yes thank-you, that was poor word choice. So you're saying it is essentially coincidence ("couldn't be subjectively changed in the viewer")? As for why it would matter, I would guess that opacity would be something of a handicap to early marine creatures. Perhaps a transparent solvent is not required for evolution, but it certainly doesn't hurt once you develop eyes. Marskell 08:06, 13 April 2006 (UTC)
Of course the light we get from the sun is ALSO in the range of energy transitions of many chemical reactions, (many chemical reactions for chemicals our living world is made of, because it evolved under those conditions. note the circularity...) EG photosynthesis rxns, etc. Here is where in the intelligent design advocates can speculate. If the sun gave off microwaves, say, than a planet to form life would have to have a mwave transparent atmosphere, chemistry of life as we know it would be impossible, would have to be different chemistry. etc. Many techincal problems. And if you try to track down solutions, it may be that eventually all alternate scenarios won't work. Then ID might say, constants of physcics are such that nuclear rxns in the sun are such that the radiation it gives off are such that on a particular type of planet with certain gaseous atomosphere at certain temperature could form life rxns that make life possible and allow life to see and cognized that the constants of physics are such that .... (It all fits together) I mean the IDists COULD make such a claim, if they were smart enough. --GangofOne 19:40, 13 April 2006 (UTC)
If water were opaque with respect to our definition of 'white', then life evolving in oceans would presumably adapt to whatever the most abundant radiation filtering through was, and the surface of the ocean would probably become prime real estate. It could lead to some interesting results, like radically different mechanisms for photosynthesis at small variations in depth. Peter Grey 03:21, 14 April 2006 (UTC)
Water transparency is vital for terrestrial as well as aquatic organisms. If water were not transparent to humans, critical eye components such as the lens and vitreous humor would be opaque. :furthermore, since vertebrate eyes evolved in ancestors to vertebrates, we inherited our vision from aquatic creatures. — Knowledge Seeker 05:40, 14 April 2006 (UTC)
Even if vision could not be developed for whatever reason, there are other ways to sense one's environment. Echolocation can be an adequate substitute for vision, and an organism living in a sufficiently dense environment (such as underwater) can sense movement around itself via a pressure sense. 84.239.128.9 18:02, 14 April 2006 (UTC)

A problem about GIMP[edit]

Hi, just recently i downloaded GIMP (latest version) from sourceforge.net, and all the help files and also animation package along with the necessary GTK. it was working fine on my laptop, but when i tried to install it on my personal computer, running winXP, during installation it said that some files were already present , so it gave me option of "renaming" them. but i decided not to rename them. so it got installed with no problem.but now whenever i try to run it, a msg appears that "an error has occured and GIMP will shut down". this error just wouldnt go. i re-installed it several times, but it didnt work, now what should i do? GIMP is great , but these problems just make open source a headache. could u help me?

Why is this an open source problem? As for Gimp, did you remove it first before reinstalling it? --Kainaw (talk) 18:38, 12 April 2006 (UTC)
yes i did uninstall it before installing it.
For more specific help here, you'll need to be a bit more specific about the errors during installation, and whether you get the same errors each time. Also, have you tried that project's help forum? --Tardis 20:15, 12 April 2006 (UTC)

Skew Universe[edit]

What exactly are the implications of a skew universe, and what are the possiblities that we may live in one ourselves? Luthinya 18:41, 12 April 2006 (UTC)

You'll have to give a rigorous definition of "skew universe" first. It doesn't seem to be a well-established scientific term. Perhaps you'd be interested in brane cosmology? Also, skew in other fields is typically a relative description; it means nothing if you only consider one object. If that's the case here, then the question "do we live in a skew universe?" is meaningless, and the "implications of a skew universe" are null. Now, if we somehow found another universe and it was skew to ours... --Tardis 20:34, 12 April 2006 (UTC)
I think this is a follow up to the question about the perpendicular universe theory that was asked a while back--172.129.106.218 00:10, 13 April 2006 (UTC)
Unless its the same person, I think he is just asking about parallel universes. Check it out. -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 01:18, 13 April 2006 (UTC)
I know which section you were talking about vaguely, since I myself have seen it, but I am NOT the same person- since I am obviously female- and as far as I know my problem does not concern parallel universes directly, which I had taken a considerable interest in a few months earlier. My question arose from an article of a scientific journal- whose name I can't recall- discussing the various possibilities of different "models" of the universe arising from modern physics. The article only contained a brief sentence concerning the skew universe so I decided to ask here to satisfy my curiosity. I have had a vague idea now- I've checked for the word skew in a mathematics article and obtained the relevant information. LCS 08:32, 13 April 2006 (UTC)

radiology[edit]

What is the flow of electrons in an x-ray tube?

See X-ray; in particular, the history section. --Tardis 20:47, 12 April 2006 (UTC)

cells[edit]

Why do lysosomes function best in acidic environments?

Maybe you should look up lysosome? I'm sure that has the answer to your homework question. --Tardis 20:56, 12 April 2006 (UTC)
This isn't sufficiently answered on Lysosome. --David Iberri (talk) 21:17, 12 April 2006 (UTC)
(After an edit conflict, and noting that this didn't immediately strike me as a homework question...)
It's really the digestive enzymes within the lysosomes that function better in acidic environments. Each of these enzymes (like all enzymes) is a protein whose ability to function is dependent on its ability to assume the proper shape. If the enzyme is in the wrong shape, it won't be able to act efficiently on its substrate. For lysosomal enzymes, having the wrong shape means not being able to perform enzymatic digestion optimally. A protein's shape is governed by its tertiary structure, which is maintained in large part by hydrogen bonds between the protein's amino acids. And hydrogen bonds are exquisitely sensitive to pH. Change the pH enough and the hydrogen bonds will be disrupted, forcing the protein to assume an improper shape (called denaturation) and therefore become less active.
This provides some measure of protection to the cell. Consider a case in which the lysosome bursts, spilling digestive enzymes into the cytoplasm. The higher pH (less acid) of the cytoplasm would render the lysosomal enzymes less active, protecting the cell from digesting itself. Hope that helps, David Iberri (talk) 21:17, 12 April 2006 (UTC)
I thought it was -- it mentioned the pH-dependence of the digestive enzymes, and the bit about their being somewhat disabled if a lysosome leaked. But the denaturation details you gave are nice. I didn't even ask the question, but thanks. --Tardis 15:37, 13 April 2006 (UTC)

Relativity and the speed of light[edit]

My friend posed the following scenario to me earlier: Assume that you have a highly efficient solar sail attached to a ship, and that you set the ship and sail in motion in space. Assuming the ship does not pass near enough to any highly massive objects to greatly affect its speed, and that it receives a steady supply of solar energy, will the ship ever exceed or match the speed of light?

I say no. Mass increase tells us that, even given a steady source of energy, the ship's mass would increase without bound as its velocity increases, and the ship would require infinite energy to meet the speed of light.

However, my friend tells me that, given Newton's F=MA, sufficient energy would allow the sail and ship to meet and exceed the speed of light.

I am quite confident of my own thoughts on the matter. However, I would like concrete mathematical or physical evidence to show my friend the error of his ways.

--Doubleplusungood 22:46, 12 April 2006 (UTC)


You're entirely correct; in fact, it requires an infinite energy (and hence infinite time) to accelerate an object with non-0 mass to c , which will, of course, never happen. The kinetic energy of the spacecratft would be E_k = m c^2 (\frac{1}{\sqrt{1 - (v/c)^2}} - 1) \! (see Kinetic_energy#In_relativistic_mechanics). As v approaches c, this number approaches infinity. Recommend a good book on relativity to your friend. --Borbrav 00:26, 13 April 2006 (UTC)
He's kind of right - sufficient energy will accelerate the ship to the speed of light. It's just that sufficient energy doesn't exist in the universe... For great justice. 01:05, 13 April 2006 (UTC)
As for concrete physical evidence, particle accelerators verify relativity all the time. You can accelerate a charged particle with changing electric fields, and as it gets closer to the speed of light, its energy grows (and therefore it acts heavier) without limit. No matter how long you keep accelerating it, it will never reach or exceed the speed of light. —Keenan Pepper 08:15, 13 April 2006 (UTC)

Hello! This is doubleplusungood again, with a few additional questions. My aforementioned friend is with me now. Here are his thoughts: 1. In the solar sail example, assume the universe is composed only of a single star and the sail device. The star is thus emitting radiation that continues constantly to hit the sail. The constant addition of energy will never reduce. Due to the absence of gravity (negligible gravity, that is), the sail will never slow down of its own right, and the continual input of energy will continue to accelerate the sail, due to conservation of energy. 2. Since light is affected by gravity (e.g. black holes), and can also be slowed down (by gravity and refraction through everyday objects, like water or diamond). Since Newton declared that only mass is affected by gravity, light must therefore have mass. In accordance with relativity, light thus cannot attain the speed of light. What is the speed of light (as light can slow down), and what is light, since it must have mass and cannot travel at a velocity of "c"? --Doubleplusungood 17:44, 13 April 2006 (UTC)

There's a very simple explanation you're overlooking: Newton was wrong. Massless particles are affected by gravity. Chuck 20:40, 13 April 2006 (UTC)
There are two types of particles: those with a rest mass and those without. Those with a rest mass cannot be accelerated to c, regardless of energy input, per above. Those without rest mass (e.g. photons) can only move at the speed of light, and have a "mass" that is related to the energy they carry. --Borbrav 22:10, 13 April 2006 (UTC)
An even simpler explanation: you have to substitute the relativistic version of F=MA. Peter Grey 03:26, 14 April 2006 (UTC)
Answering point 1) of Doubleplusungood. Let's simplify the problem: forget relativity, use only newton's mechanics. Let the Star be in point (0,0,0) and the sail moving along axis x. Newton's equation for sail, projected on axis x, will look like this:
M*ax = -G*M*m/x^2 + C/x^2, where C is a constant
where ax is projection of sail acceleration on axis x. C/x^2 is force, caused by star's light: as the sail moves from the star, the spacial angle, at which it's seen from the star is reduced as 1/x^2. It's just geometry. (And the light intensity is the same in the same spatial angle.) C is some constant, depending on intensity of Star's shining and surface of the sail. OK? We can rewrite the right hand of equation as Y/x^2, where Y is new constant, positive or negative. This new equation M*ax = Y/x^2, is the same equation, as the equation of a charge in electrical field. So, the answer is this: sail will never gain infinite speed. It will gain some constant speed if Y>0, and will return to Star if Y<0.
Just, guys. Don't stop thinking and finding new problems. Currently i know better; tomorrow you'll do. :-) ellol 11:30, 14 April 2006 (UTC)
Also, as the sail approaches c relative to the light source, the light will be redshifted further and further, constantly decreasing the energy available to push the sail, even if the light was in a coherent straight beam. Tzarius 01:36, 15 April 2006 (UTC)
Another point -- the "slowing down" of light in refraction doesn't really have anything to do with relativity -- it's the result of the electromagnetic wave that makes up the light coupling to the electric fields in the material doing the refracting. The "fundamental speed limit" c, the speed of light in a vacuum, is unchanged. A particle can go faster than the "local" speed of light in a medium as long as it's still going slower than c. This creates the light equivalent of a sonic boom -- Cherenkov radiation. --Bth 05:43, 15 April 2006 (UTC)

Excretion and body temperature[edit]

Is it possible to lower one's body temperature by urinating or defecating? The answer is probably a resounding no, but I want to know for sure. Bhumiya (said/done) 22:47, 12 April 2006 (UTC)

No. Poop and pee are the same temperature as the human body as long as they're in the human body. So there's no chilling or warming effect by getting rid of either of them. - Nunh-huh 23:30, 12 April 2006 (UTC)
Not by urinating or defecation but by eating and drinking it is possible because all of that food/water has to be heated. Just look at the energy balance. Assume you take in all food and water at room temp. (25 C) for one day. Assume it comes out of your body at 98.6 F (37 C). Then, 12 C or 12 K is the difference. Now find the specific heat of the composition of urine, probably around water, which is about 4.18 J/(g*C). Approximate urine as water again and at 1 g urine / 1 mL urine
..then for every 1 mL of water you consume at room temp you're burning 50 J which is .012 food Calories (kcal). I think this is negligible. Even if you drank 10 liters of water a day that'd only be 120 Calories of heat exiting your body. That's nothing.
Because I don't have an approximation of the specific heat of feces I don't know how much energy it takes to heat it, but you can bet that based on our water approximation that the energy spent to heat up the food you take in is nothing compared to the Calories in the food (or even if the food has no Calories it would still be so small as to be negligible).
So no, I don't think it's physically possible to intake so much food and water as to decrease your body temp.
-Snpoj 02:13, 13 April 2006 (UTC)
I have no idea why Snpoj completely changed the question. The question was whether you can reduce your body temperature by urinating or defecating, and Snpoj concludes: "So no, I don't think it's physically possible to intake so much food and water as to decrease your body temp." Wha...?
In any case, I disagree. First, it must be remembered that human body temperature varies depending on the area of the body. The internal organs are generally warmer than the extremeties. For example, the torso is, under most circumstances, warmer than the fingers and toes.
Thus 98.6F is merely the mean temperature of the healthy human body. The fingers and toes are no doubt lower in temperature, and the innards, for example the bladder, is somewhat higher.
Since urine is excreted from the bladder, it goes to reason that its temperature is somewhat higher than the mean temperature of the body, and by urinating and eliminating this warmer than average liquid, the mean temperature of the body naturally decreases. (What else would create the "shiver" effect when a guy pees?) ;-) Loomis51 00:34, 16 April 2006 (UTC)
As a liquid, urine will evaporate, so the truly desperate might try urinating on themselves in order to take advantage of the enthalpy of vaporization. Isopropyl 08:24, 13 April 2006 (UTC)
Or get into watersports with a friend. JackofOz 00:00, 15 April 2006 (UTC)

April 13[edit]

Perfect Secrecy in a Cryptographic System[edit]

According to Claude Shannon's paper, perfect secrecy is obtained when |P|=|C|=|K|. Is it admissable to have |C|=|P|<|K|? i.e. if I have a cipher where Pr(y|x) = Pr(x) does the size of the key matter as long as it isn't smaller than the C or P space? This is all assuming that the keys are equally possible and unique. Any help would be greatfully appreciated, C.Meyers

Have a read of one-time pad, and consider what would happen if any part of the key longer then the plaintext is simply discarded by both sender and receiver. --Robert Merkel 07:08, 13 April 2006 (UTC)
The statement that I have in my lecture notes from the crypto module I took a year ago says that perfect secrecy exists iff |K| \ge |C| \ge |P|, where K, C, and P are the sets of all keys, ciphertexts, and plaintexts, respectively (and |X| is the cardinality of set X.) This is slightly different from the relation you've given, where all three sets have to be the same size. -- AJR | Talk 12:29, 13 April 2006 (UTC)

Cheese![edit]

I assume individually packaged cheese slices solved two problems:

1. consumer demand for pre-cut cheese (i.e. not having to cut out a slice from a big block, just like sliced/unsliced bread)
2. consumer demand for cheese with a longer expiration date. Individually wrapped cheese will last much longer than cheese in a block which supposedly goes bad after about 5 days because once you open it, you've opened an manufactured air-tight seal.

Question: is assumption 2 correct? (how bout 1?)

-Snpoj 02:25, 13 April 2006 (UTC)

  • 1 makes sense, 2 less so. Many of the best types of cheese last a lot longer than a few days (though pre-processed ones may not, of course). In fact, many types of cheese are far better after they've matured for a considerable length of time. Grutness...wha? 03:57, 13 April 2006 (UTC)
Assumption 2 is incorrect. My friend (who's worked with cheese professionally) tells me that cheese is pretty much good until it molds, and even then those parts can just be cut off. Also, if exposure to air was a problem, then you would want to reduce the surface area exposed. Isopropyl 08:21, 13 April 2006 (UTC)
I'll chime in with a bit of a note on this. While cheese that is exposed to air doesn't go bad itself, it will dry out. For softer cheeses with higher moisture content, this definitely affects the texture and the quality of the eating experience.
A minor caveat to the 'just cut off the moldy bits' approach—mold and toxic mold secretory products can travel a short distance into the cheese beyond the extent of visible contamination. Again, this is more of a concern in soft, moist cheeses. The bold are still welcome to cut off the mold and enjoy; just remember that you may want to cut a bit of a margin around the mold.
Finally, individually wrapped cheese slices do let you avoid the mold problem altogether. Presumably, a person will only open a slice with the intent to eat it (nearly) immediately; there is no time for mold spores to settle and grow. In a sense, I'd say that assumption 2 holds because people want to avoid the perception that their cheese has gone bad, whether or not it is still safe to eat.
The major problem with the processed, prepackaged, hermetically-sealed cheese slices is that – in my entirely subjective opinion – they don't taste very good. They're also only available in a limited number of flavors. TenOfAllTrades(talk) 12:37, 13 April 2006 (UTC)
A good cheese will last months, though its appearance will get worse and it might frighten some people. Consider (3) it allows people who don't trust their small children with knives to still have them make a cheese sandwich (4) it provides a controlled and measured amount of cheese, rather than a rather random personal slice (5) it is easier to snack on the pack outside the kitchen. Notinasnaid 09:10, 13 April 2006 (UTC)

cgi script code demands unix?[edit]

I looked at a cgi script and it's got '$mailprog = '/usr/lib/sendmail -i -t';' in it. Does that mean it can't be used on a Windows based server? Can you get unix emulators for windows like you can get Wine for unix/linux...? --Username132 (talk) 05:02, 13 April 2006 (UTC)

Don't know about the first question but I think this is a popular linux emulator for Windows -Snpoj 05:06, 13 April 2006 (UTC)
cygwin is not a linux emulator. It does provide parts of POSIX though. -WhiteDragon 18:26, 20 April 2006 (UTC)
I don't think there is a version of sendmail compiled for Windows. You could try Cygwin, as Snpoj said, but I don't find that to be entirely reliable, especially if you would be planning to use it for server purposes. -- Daverocks (talk) 06:39, 13 April 2006 (UTC)
According to [22] there is a version of exim that provides sendmail functionality. --WhiteDragon 18:26, 20 April 2006 (UTC)
You could rewrite the script so that it uses a mail service on Windows instead (you'd have to check what mail service is available, there is no one standard). Notinasnaid 09:07, 13 April 2006 (UTC)
Actually, I think you do have MAPI --WhiteDragon 18:26, 20 April 2006 (UTC)

PC monitors on TV[edit]

Why does a monitor on TV (like in the news) have weird bands going down it over and over? --Username132 (talk) 05:24, 13 April 2006 (UTC)

  • Cathode ray tubes create pictures by scanning from top to bottom. So if you point a television camera at a CRT screen, each frame [29.97 per second in NTSC, 25 per second in PAL] will see the screen at a different part in the cycle, and a different part of the screen will look bright. -- Filliam H Muffman 06:01, 13 April 2006 (UTC)
    • This is an issue that occours whenever a continuous signal is sampled too slowly with inadequate prefiltering (prefiltering visual data before sampling it is very hard because of the sheer bulk of it). A signal that the sampler is too slow to correctly capture (e.g. thats changing faster than half the sample rate) will manifest itself as a slower signal at the difference between the original frequency and the closest multiple of the sample rate. Other common examples of such effects on TV are racing car wheels (they appear to slow down and then stop again as the car accellerates) and helicopter blades (they are invisible to the naked eye but appear as black bands rotating in a semi-random way on TV) Plugwash 23:22, 16 April 2006 (UTC)

Can't ping 127.0.0.1[edit]

I run Mandriva Linux version 2006.0 and I've struggled with this problem for quite a while, namely that I can't ping 127.0.0.1 (local loopback), nor can anything make a connection to it. I can use ping to ping everything else (e.g. yahoo.com, wikipedia.org), so ping is not the problem. This is what happens when I try to ping 127.0.0.1:

[root@davidlaptop ~]# ping 127.0.0.1
connect: No buffer space available

Configuration of the loopback interface is fine:

[root@davidlaptop ~]# ifconfig lo
lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:9279 errors:0 dropped:0 overruns:0 frame:0
          TX packets:9279 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:524961 (512.6 KiB)  TX bytes:524961 (512.6 KiB)

Some people have asked me about my /etc/hosts file, but this is also normal:

[root@davidlaptop ~]# cat /etc/hosts
127.0.0.1               davidlaptop localhost

Now here is the strangest part. After bootup, I am able to ping 127.0.0.1 with no problem. However, after about 5-10 minutes, pinging 127.0.0.1 suddenly stops working, again yielding the message "no buffer space available". And although most of the time I am unable to ping 127.0.0.1, sometimes it suddenly starts working for seemingly no reason. Usually it stops working after this as soon as I stop being active on the Internet (my Internet is through interface wlan0). This problem is extremely frustrating as it causes me to be unable to test my Apache server, my FTP server or use Tor at all. Does anyone have any idea why it might be happening? I can provide more details on request. -- Daverocks (talk) 07:02, 13 April 2006 (UTC)

These links are the closest that I could find to a solution, although there is no confirmation that the solution worked for all involved. [23] Another link is [24] they have an even longer explanation and it says solved, but I am not sure that the problem is the same. Ansell 07:54, 13 April 2006 (UTC)
Thanks, those links are quite helpful, more relevant than the ones I was able to find. Particularly the first one you provided had helpful information. I'm still not sure what's going on, and I still haven't "definitely" solved the problem. However, something seems to be happening when I disable the lisa service and stop cupsd. Thanks for your input. -- Daverocks (talk) 01:44, 14 April 2006 (UTC)

Black Holes and Gravity[edit]

If Black Holes may possess a gravitational field so great that even light cannot escape it (except under exceptional circumstances such as Quantum tunnelling), then is it implausible to assume that a same type of mass-energy may be generated within the universe that will really allow superluminal velocities? I know that the square root within the transformations of Special Relativity turns imaginary when the velocity exceeds the speed of light, and thus explained away as making no sense, but considering the implications again of a Black Hole- if the gravitational field may be generated so great that even the photon cannot escape it, then this field, being a curvature in spacetime caused by mass-energy of some sort, must similarly lead to the possiblility of an energy level capable of exceeding the speed of light. In that case, maybe the imaginary square root may be taken to mean something even more esoteric. Or is something still missing from the story? All help appreciated. LCS 08:44, 13 April 2006 (UTC)

is it implausible to assume that a same type of mass-energy may be generated within the universe that will really allow superluminal velocities?
Yes, for a mass to reach superluminal velocity, than that would require a kinetic energy as being infinity. How unlikely. Gravity and electromagnetism are separate forces. -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 10:11, 13 April 2006 (UTC)
See tachyon. There's no evidence for them. —Keenan Pepper 11:06, 13 April 2006 (UTC)
As you probably already know, travelling faster than light means travelling backwards in time. The implications of this for causality are the main reason why faster than light travel is considered implausible. But there are some more Wikipedia articles that deal with this whole subject. Try reading, as already mentioned tachyon, but also wormhole, Faster-than-light and Grandfather paradox. Simon A. 12:38, 20 April 2006 (UTC)

java[edit]

I sort of know that java is a program [to help you?] but do you need it on your computor? I get more updates to install on my M/C than I do from Microsoft and it's very persistant to get me to install them I have XP with service pack 2 installed 60.229.175.88 09:12, 13 April 2006 (UTC)

It is useful if you want to see Java Applets on webpages, or if you want to run Java based programs on your computer. The Java download here [25] enables this. Ansell 09:32, 13 April 2006 (UTC)
Java is often used to show you part of a web page. You probably have it already. Bear in mind that Microsoft offer you updates because you already have an older version of the software and if they are security fixes it may be very important to install them. Notinasnaid 09:33, 13 April 2006 (UTC)
Never ever accept Microsoft Updates. You'll just be putting a lot of hard-working hackers out of business. Please, someone, think of all the poor hackers. --Kainaw (talk) 12:02, 13 April 2006 (UTC)
Untrue, Kainaw : the old game betwen fortress and cannon must go on. If flaws are not corrected, then poo' hacker is unemployed. --DLL 18:01, 14 April 2006 (UTC)
You are correct. Let me rephrase: Never ever accept Microsoft Updates. You'll just be putting a lot lazy script-kiddies out of business. Please, someone, think of all the lazy script-kiddies. --Kainaw (talk) 18:14, 14 April 2006 (UTC)

snake[edit]

My daughter wants to know from which part of snake's body its eggs come out ? Not the process of mating or reproduction but somthing like from where exactly the baby comes out.

Thanks

At the risk of stating the obvious, the vagina. (Google produces some fascinating results, but you may not want your daughter to see them). HenryFlower 09:34, 13 April 2006 (UTC)
The Snake article has a reproduction section that doesn't exactly entail where the eggs come out, however, it does explain a bit about some snakes which do not lay eggs, rather keeping them inside them and/or giving birth to live young. I assume the position that they lay eggs from would be about 2/3rds of the way down the body, however I can't seem to find any sources for that right now. Ansell 09:40, 13 April 2006 (UTC)
This page claims a video, which I have not watched: http://www.arkive.org/species/ARK/reptiles/Coronella_austriaca/more_moving_images.html. Notinasnaid 09:49, 13 April 2006 (UTC)
You can't see the whole body of the snake in the video, so it's hard to judge, but I'd say it's about 3/4 of the way down. On the bottom, of course. Interestingly our vagina article mentions that the vagina leads to the cloaca 'in some reptiles', but doesn't say which reptiles. HenryFlower 09:59, 13 April 2006 (UTC)

The same question was asked and better answered at "Ask A Scientist" - Zoology Archive - Snake Delivery - 1/19/2004:

"most snakes lay eggs (oviparous) some of them deliver a baby, outside the eggshell ready to live (viviparous). The reproductive system of the reptiles including the snakes are simpler than the one of the mamals and resembles the birds. There are both in males and females an opening to the exterior called "cloaca". The cloaca is the passage from a internal chamber into which the digestive, urinary and reproductive systems empty. So both the baby snake or the non-hatched egg go to the exterior through the cloaca. Incidentaly, inside the female snake body there is a tract called oviduct provided with conditions for egg fertilization and embryo formation." [26] WAS 4.250 11:32, 13 April 2006 (UTC)

The human brain[edit]

I’ve was told that researches were made about our brain’s function that found that when we see things and when we imagine things, the brain uses the same parts. Meaning that our brain cannot differ between what it sees to what it remembers/imagines. Can you please guide me to those researches? Thank you


There was an article all about this in the February/March Scientific American Mind pages 18-23. Called "Picture This." by Thomas Grueter. It refrences:
Image and Brain: The Resolution of the Imagery Debate. Stephen M. Kosslyn. MIT Press. 1996.
Return of the Mental Image: Are There Really Pictures in the Brain? Zenon Pylyshyn in Trends in Cognitive Sciences Vol. 7. No. 3, pages 113-118; 2003.

If you can't find it on the internet, I can scan in the article for you without any trouble. See my talk page User_talk:Mac_Davis. Here is a search for zenon pylyshyn cognitive [27].

-- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 10:22, 13 April 2006 (UTC)

A myth or a true story?[edit]

I was told that the Indians couldn’t see Columbus’s ships arriving because they didn’t have that image in the image bank in their brain. Is it a myth or a true story?

Hahahahah! It is a myth. Just because you haven't seen anything before doesn't mean you can't see it! How do you think you see things that you haven't seen before? -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 10:13, 13 April 2006 (UTC)
It's true. I kept telling 16 year old girls that I cannot see their nakedness because I do not have that image in the image bank in my brain and so if they take off all their clothes then all I can see is a blank spot where their nakedness is. Ohanian 10:33, 13 April 2006 (UTC)
Do they believe you? I would think not, but then again people may be more guillible than I think. --Bowlhover 01:53, 15 April 2006 (UTC)
I heard that story. I believe it was from a documentary on Amerigo Vespucci. In his novel about the New World, the native women were beautiful, big breasted, and extremely dumb. The men were stupid and lazy and handed over tons of gold and silver to the white men to have sex with their women for them. His story was, obviously, not written from real accounts. --Kainaw (talk) 12:00, 13 April 2006 (UTC)
Definitely a myth. This story has been spread a bit by the movie What The Bleep Do We Know!?, a "documentary" which is not at all scientifically accurate. rspeer / ɹəədsɹ 15:35, 13 April 2006 (UTC)
I believe "What the BLeep" got the idea from some anthropologist's writing. I am trying to track down whose. Any body know? I KNOW this story was out there before that movie came along. Plus, the movie explains it badly and exaggeratedly. --GangofOne 19:06, 13 April 2006 (UTC)
I'm not entirely sure about the truthfulness of What the bleep do we know, but a similar thing I heard about when going through the topic of evolution comes to mind, I'll try to retell the story briefly:
An explorer went to live with a jungle-dwelling people, who obviously had never left the jungle, he befriended them and decided to take one of their people to his world. On their way to a city, they crossed a savanna, the short jungle-dweller (being short is a nifty adaptation for jungle life) spotted a couple of grazing animals in the distance, he recognized them as flies, and tried to wave them away with his hand.
The reason for this is that the jungle-dwelling man had never ever seen anything so far away, and his concept of distance was limited to perhaps five metres away at most, as jungles don't really have that much open space. In a sense, he could not possibly imagine something that big being visible from that distance, and could thus not know that things look smaller with distance. -Obli (Talk)? 21:38, 13 April 2006 (UTC)
I'd be suspicious of that one too. Most stories about the silly things "savages" do are false at best and insidious at worst. --Fastfission 01:36, 14 April 2006 (UTC)
There are many reports of pygmy tribes from the forest who have difficulty working with directions that go over long distances and gawking at wide-open plains. It is really no different than Americans failing to comprehend a kilometer and gawking at fields covered with green instead of cement. --Kainaw (talk) 12:50, 14 April 2006 (UTC)

Well, it's definitely false. Of course you can see things you've never seen before. When you were born, you didn't have any images in the "image bank" of your brain. Does that mean you're going to be blind for life? --Bowlhover 18:34, 14 April 2006 (UTC)

Cognitively blind. If you don't have a concept for something, you don't register it. Babies are such, until they are taught, (by which I mean interactions with reality, not in school). Concepts, that is to say, bundles of recurrent sensations that have been reified, are then defined in terms of other concepts available to the developing conscious being. However, if you have bad conceptual scheme through which you, as adult, perceive everything, then you are also insulated from the new; this is also a tragedy, for which the cure is claimed to be various spiritual/psychological processes that are available for a reasonable fee (classes now forming), but generally just substitute one conceptual scheme for another. Anyway, there are many examples from psychology experiments. They flash a playing card for a fraction of second, to be identified. Well, the trick is they make a black King of Hearts, say, but the experimentees CAN'T SEE IT, and say King of Hearts , or King of Spades , and NOT WHAT IT IS. That black K of H is like the ships of the Europeans to the indigious; doesn't fit into their conceptual schema, at first. This general state of affairs is definitely NOT a myth. Read The Social Construction of Reality for starters. --GangofOne 22:05, 14 April 2006 (UTC)
Hmm, not entirely comfortable with that exposition. Babies may be said to be cognitively blind, but only because it takes many months before "the penny drops" and the baby suddenly understands that he/she is separate from "other things". Until then, to the child there is only one all-encompassing "thing". That's not to say they can't see and desire to touch physical objects, but they still don't make any cognitive distinction between themself and the object. But when a Spanish galleon appears in the harbour, the 15th century American native definitely sees it and definitely knows it is a strange object external to themself. Whatever name they give it would simply reflect their lack of a frame of reference at that time. We refer to UFOs as "flying saucers" too, but I'd bet that's not what they are. JackofOz 23:52, 14 April 2006 (UTC)
Gangofone, are there any psychology experiments in which participants are shown something bizarre, something they haven't seen before, and the person conducting the experiment asks the participants if they can see the object? The experiment you gave as an example is irrelevant--the participants can't see the card very well if it's only flashed across their eyes, so they take whatever they managed to see and compare it with what they know about poker cards, to find the card that matches best. If the participants were given a chance to carefully look at the cards, I'm sure they could see that the king of hearts is black (for example). --Bowlhover 01:53, 15 April 2006 (UTC)

I've never seen a black king of hearts in my entire life. Does that mean that if I was shown one it would be invisible to me? Before I saw Star Wars for the first time, I had never seen a wookie before. Why wasn't Chewbacca invisible to me? The whole idea is definitely a myth, and not even a very believable one at that. Loomis51 00:55, 16 April 2006 (UTC)

"I've never seen a black king of hearts in my entire life. Does that mean that if I was shown one it would be invisible to me?" A rather strange argument, especially for a lawyer. I don't have all the details of the card experiment from Psychology 101, probably could find it somewhere. The experimentees who don't see the black king of hearts, are not asked "Did you see that?", they are asked "What did you see?" They have no difficulty identifying the red K of H or other regular cards. If they are allowed to examine the deck, and are thus clued in, THEN they have no difficulty recognizing the black K of H etc. So it's not the breifness of the exposure that is preventing them from seeing the reality, because they see reality otherwise just fine; the problem is in their concepts of reality. The story is not about optics, it's about concepts (preconceptions) and perception. --GangofOne 07:00, 16 April 2006 (UTC)
I've never read the original paper before, but here it is: http://psychclassics.yorku.ca/Bruner/Cards/ Classics in the History of Psychology "On the Perception of Incongruity: A Paradigm", Jerome S. Bruner and Leo Postman (1949) Harvard University. First published in Journal of Personality, 18, 206-223. --GangofOne 07:10, 16 April 2006 (UTC)
I see this experiment is also mentioned on p62 and 112, Kuhn ,THe Structure of Scientific Revolutions, 1962 . "Until taught by prolonged exposure that the universe contained anomalous cards, they sww only the type of cards for which previous experience had equipped them... What a man sees depends both upon what he looks at and also upon what his previous visual-conceptual experience has taught him to see..." Also mentioned in this CIA textbook for analysts: http://www.cia.gov/csi/books/19104/art5.html Chapt 2 "Perception: Why Can't We See What Is There To Be Seen?", mentions Jerome S. Bruner and Leo Postman, "On the Perception of Incongruity: A Paradigm," in Jerome S. Bruner and David Kraut, eds., Perception and Personality: A Symposium (New York: Greenwood Press, 1968).
I believe it was Columbus who wrote in his log that he saw mermaids, but they weren't as beautiful as expected. Some say he maybe saw manatee, but maybe he really saw a swimming wookie. --GangofOne 10:12, 16 April 2006 (UTC)

The original question asked was if it was true that the Indians could not see Columbus' ships arriving as they had never seen large ships before. The question seems to me to clearly have implied that the Indians saw nothing, i.e. the ships were invisible. However, if the question is whether or not the Indians recognized these large objects that they did in fact see to be ships, then the answer would possibly be no. But that doesn't seem to be what the questioner was asking. The question was whether the Indians were able to see Columbus' ships at all, which clearly they were. Loomis51 13:37, 16 April 2006 (UTC)

I concur. If you have never seen a key before and someone showed you a brass one, you would say that you saw a brass object, but you would definitely not say you saw a key, because the concept in words did not exist for you and you don't have the word in your vocabulary anyway. Luthinya 10:08, 17 April 2006 (UTC)

Computer Network Tockin Ring[edit]

Dear All,

I have some confussion related to Computer Networking below theories/terminology, If anyone can clear me below points. than I highly be thankfull.

  • 01: Why saying? "Token Ring" is Local Area Network Technology
  • 02: Why "Token Ring" is not inlist in Channel Access Methods?
  • 03: Please tell me difference between "Network technology, Access Method and Network Protocol"

Thanks.

M.Sadiq Qadri [enough with the personal info]

Why do you care whether a "token ring" is a LAN or not. As long as it's implemented correctly it will work. The only time, I care about the definition of "token ring" is when I need to hand in my computer science assignment at University. Ohanian 10:29, 13 April 2006 (UTC)
Token ring is it's own access method. Think about it, terminals can *only* speak when they have the token. The Token Ring article does quite a good job at describing it. --Jmeden2000 13:16, 13 April 2006 (UTC)
Token Ring is a LAN technology, it just uses a different structure for determining which system is transmitting data. In fact modern Token Ring systems use the same physical infrastructure as Ethernet. The reason Token Ring is not commonly used is 1) Originally IBM propriatary technology. 2) More expensive due to 1. You may want to look up Local Area Network, Token Ring. If you want more detailed information on Networking I would suggest you by a used copy (new is $65+) of a Comptia Network+ exam. As these guides cover the basics of Networking and a lot of the terminology of Networking.--Tollwutig 15:00, 13 April 2006 (UTC)

Fundamental forces, "weak charge"[edit]

Electromagnetism is the coupling of photons to electric charge. Gravity is the coupling of hypothetical gravitons to all energy. The strong force is the coupling of gluons to color charge. The weak force the coupling of W and Z bosons to... what? My physics book mentions "weak charge", but doesn't go into any detail and doesn't say what kinds of particles have it. I notice we don't have an article on it either. Is there really such a thing as "weak charge"? —Keenan Pepper 11:21, 13 April 2006 (UTC)

No fundamental weak charge exists. "Originally, weak interactions were thought to be separate from electromagnetic forces. Eventually, three fairly massive particles were discovered: W+, W-, Z. The weak force is an electromagnetic interaction producing one of these particles. The particle travels then is absorbed through electromagnetic interactions with another particle. Although the Z-particle has no electric charge, it does have a spin. It can interact with magnetic force. Standard electromagnetic force is transmitted by photons of light. Weak force is transmitted by these "weak" particles. Still the actual interactions are the based on the same force." [28] WAS 4.250 11:47, 13 April 2006 (UTC)

All leptons and quarks with left-handed chirality are susceptible to the weak force. Notably, as a result it's the only force to affect neutrinos, and the only force that can cause flavour changing processes (thus it's responsible for beta decay, though note that the Z boson cannot cause flavour changing -- there are no flavour changing neutral currents). See weak interaction for lots more. But as per WAS's quote there isn't an identifiable "weak charge" as such. --Bth 12:00, 13 April 2006 (UTC)
See Weak hypercharge. I'm guessing that that corresponds to the weak coupling constant, or maybe it's weak isospin. Cedders 00:30, 14 April 2006 (UTC)
Well, I still don't understand it, so I guess I'll just have to wait until I take... Particle physics? Quantum field theory? What? —Keenan Pepper 01:04, 14 April 2006 (UTC)
The thing is that the weak force comes out the other side of the spontaneous symmetry breaking of the electroweak interaction. At "high" energies, the electroweak force couples to weak hypercharge. At low energies, the EM force couples to electric charge and the weak interaction is the mess that's left over when you separate that out from the electroweak interaction. As such the thing it couples to is rather complicated and messy (it doesn't couple to weak isospin, really: weak isospin is a symmetry of the weak interaction the way isospin is for the strong). We could really do with a page on Wikipedia that serves as an introduction to the all the gauge stuff, though -- you could argue that all these articles need more context for the non-specialist than they currently have.
Just for the record, though, I took a few particle physics courses, and I never really got a good sense of the weak force coupling to some specific property (though maybe I wasn't paying enough attention); it was always taught primarily in terms of what it did. --Bth 09:30, 14 April 2006 (UTC)

CDMA 2000[edit]

Qualcomm says CDMA 2000 provides an always-on Internet connection. What does it mean and how does it work? How is always-on different from other type, that is not always one in previous cell phone technologies?

I presume it means it is always connected, like broadband, rather than only connected when you connect it, like dial-up. For great justice. 15:40, 13 April 2006 (UTC)
Some unconventional ISPs may claim they are "always-on" when in fact they only connect when information is transferred. Normal ISPs can't claim that because idling would be impossible and they'd get a lot of pissed off customers, but that kind of service is very plausible for cell phone technology.

Cross border complexities related to the IT industry in India[edit]

What cultural bias exists towards western economic philosophies as thsy relate to the IT and Software industry in India?

Did the homework question also misspell the word they? hydnjo talk 14:56, 13 April 2006 (UTC)
The instructions above for answering questions specifically states to be nice. Spelling flames and assumptions about the origin of the question (without even answering the question) isn't very nice. As to the question, googling '"western economic philosophy" india software' got nothing, but '"western economic" india outsourcing' got lots of interesting hits, including:

and lots of others. I didn't find anything on Wikipedia, but maybe someone else will.--Anchoress 21:24, 13 April 2006 (UTC)

Width of the United States[edit]

How many miles wide is the United States? I could not find this statistic in United States nor Geography of the United States. Thanks. -- Reinyday, 17:35, 13 April 2006 (UTC)

This question is not very well-defined. First we must specify what portion of the Earth we designate as "the United States". But it's not very interesting to say that the US is typified by the distance between Hawaii and Maine, as that's certainly not representative. So let's suppose you mean the contiguous United States. Obviously even that is not a rectangle (even disregarding the curvature of the Earth), and so does not have a single "width" or "height". But presuming that by "width" we mean "east-west extent", we can talk about the lengths of various lines of latitude running through the country (these will be of many different lengths). As a very rough approximation, using the Extreme points of the United States article, I see Lubec, Maine at 66°59′5″ W, and Cape Alava at 124°43′59″ W. They're not at the same latitude -- about 3° different -- but it's close. The portion of the latitude line midway between theirs (about 46°25′ N) between their longitude lines is (using the quadratic mean radius of Q_r=3,959.871\mbox{ mi})
Q_r \cos(46^\circ25') (124^\circ43'59''-66^\circ59'5'')=2751.5 \mbox{ mi.}
A similar expression using San Diego, California and Miami, Florida (though they are 7° apart in latitude, so this is a poorer approximation) gives 2237.4 mi. The best one can really say from these figures is that the "width of the US" is 2500\pm250\mbox{ mi}. (Remember that these are not great-circle distances; the shortest route from (40°N,90°W) to (40°N,80°W) is not to go due east. But the differences at these latitudes are on the order of a percent or so; the errors in averaging the latitudes are larger.) --Tardis 18:20, 13 April 2006 (UTC)

If you define the US in terms of effective control, we control land and water all across the globe, and indeed into space. If you define US as legal sovereign teritory by law, our embasseys are technically our sovereign territory, and again we are global. If you define US as States and territories we entend from at least Maine to Guam and probably further, but I'm not gonna look up every island the UN assigns us control over. The distance of the two points in Alaska that are furthest from each other is interesting and similar to Canada and Russia useless distances. It is all about definition. Something to ponder: When you find the right way to ask a question, the question is the answer to itself. WAS 4.250 20:43, 13 April 2006 (UTC)

Or you could go from Hawaii to Florida, or Hawaii to Alaska, or Florida to Alaska for even longer distances. -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 23:58, 13 April 2006 (UTC)

This is the cousin of a question I asked about a year ago and never got much of a response. It's about crows flying within the borders of a country. How would one go about accurately determining the greatest "straight-line" distance between any two points within a contiguous area? E.g. a glance at a map suggests the longest line within the 48 contiguous US states might be from somewhere on the west coast near Seattle to somewhere on the east coast in Florida, but that's very rough. Is there a more accurate measurement? Does a list of longest crow-flights by country exist anywhere? JackofOz 23:22, 14 April 2006 (UTC)

You basically want to know the diameter of the circumscribing circle for whatever area (great-circle diameter for a circle on the surface of the earth, of course). (Note, however, that if the area is concave, the longest line may leave the area, which you might not want; it hardly counts as a long line in the U.S. if it goes through Mexico!) Certainly such a determination is possible, and the answer is well-defined up to such annoyances as erosion and altitude, but I know of no "easy" algorithms to do it. I think if you treat the area as a planar polygon (which might be okay for small areas on the earth), there's some sort of linear algebra approach. --Tardis 20:01, 19 April 2006 (UTC)

Fractal Structures in natural landscapes may also cause you necessary problems. Luthinya 12:06, 18 April 2006 (UTC)

Protiens and Sugars[edit]

Where might I find a list of the important protiens and sugars that build the human body? Specifically, something that will help me in understanding how humans decompose at teh chemical level. 64.198.112.210 20:20, 13 April 2006 (UTC)

List of proteins WAS 4.250 20:30, 13 April 2006 (UTC)

A list of proteins and sugars won't give you what you need. Try decomposition, though it's not too detailed, it may get you started. There was a book called something like Corpse that discussed this, too, but I can't quite think of the exact title. - Nunh-huh 20:57, 13 April 2006 (UTC)
Ah, but they didn't discuss it chemically. Corpse was lovely, but it was more about corpse fauna and time-of-death determination than anything else. DuctapeDaredevil 03:19, 14 April 2006 (UTC)
I agree that a list won't be much help. What happens chemically will depend on what's causing the decomposition - bacteria or microorganisms will be quite different to what happens in cremation. You might take a look at Amino acid, Denaturation_(biochemistry), Glycoprotein, and Chemical_makeup_of_the_human_body. There's also decomposition Putrefaction and rancidification. Looking from the point of view of preventing decomposition there's the Mummy article. Richard Taylor 04:13, 15 April 2006 (UTC)
Thank you very much! 64.198.112.210 19:20, 19 April 2006 (UTC)

Bomb defusal[edit]

I was watching a certain movie over the weekend, and it contained a scene where a bomb is being defused Hollywood-style: a guy with wirecutters clipping the red wire. Does this have any factual basis? Is there a history of bombs being defused in this fashion? Isopropyl 22:50, 13 April 2006 (UTC)

It's the correct way to defuse a Hollywood-style bomb: one with a half-dozen sticks of dynamite wired to an alarm clock. Our bomb disposal article covers how real-world bombs are taken care of. --Serie 23:55, 13 April 2006 (UTC)
Thanks! Isopropyl 02:42, 14 April 2006 (UTC)

I don't know, but I'd like to add a similar question. What is the big, red LED readout for on such Hollywood-style bombs? Is it there for the convenience of those who just may be standing by the bomb, so they'll know when they'll be blown up? If so, that's very considerate of the bomb designer, don't you think? Erik the Rude 23:20, 13 April 2006 (UTC)

Unless it's a trap; #15. Melchoir 00:06, 14 April 2006 (UTC)
I have another question: why do bombs on TV often beep (they also have a red LED that flashes) before exploding? I'm guessing that it's for the same reason as what Erik the Rude said--so that people who happen to be near the bomb have time to escape. --Bowlhover 17:41, 14 April 2006 (UTC)
Tradition. The first design for a clock-based time bomb consisted of a mechanical alarm clock with a percussion cap or other impact-based explosive attached to one of the bells as a detonator. Because of this, if the detonator took a few hits to trigger, you'd hear the alarm ringing before the bomb went off. --Serie 20:16, 14 April 2006 (UTC)

April 14[edit]

Ramjet[edit]

I was wondering if anyone could give me a few really nice links on how to build Ramjets? Patrick Kreidt

Ramjet -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 00:58, 14 April 2006 (UTC)

Dermatographic urticaria[edit]

Is this disorder genetically inherited? --218.102.207.71 00:55, 14 April 2006 (UTC)

In general, Urticaria (also known as hives) is not something that can be passed to others, be it either genetically or through contact. However, if there is something causing this reaction, that stimulus may be transmissible. For the most part, hives are caused by allergic reactions, and the propensity for allergies can be passed on genetically. Therefore, in a situation where two individuals both are allergic to a substance, if that substance is transfered via physical contact from one to the other it may appear that the urticaria was transferred.

There is another type of urticaria that is not a syptom of an allergic reaction. These hives can be brought on by periods of extreme emotions. This type of urticaria tends to be more prevalent in certain populations, suggesting that it can be passed on genetically. Emotionally induced urticaria, however, usually do not last more than a few minutes and very rarely require treatment of any kind, prophylactic or otherwise.Tuckerekcut 03:12, 14 April 2006 (UTC)

I don't think anyone knows for certain if dermatographic urticaria is genetically inherited. It may be due to the development of one's particular immune system which is a product of one's environment and genetics. - Cybergoth 04:45, 14 April 2006 (UTC)

Combining CC-BY-SA[edit]

I wanted to combine a CC-BY-SA 2.0 and CC-BY-SA-2.5 image. Is there any changes between the two licenses that would make this impossible? I assume this is doable, but I wanted to make sure, as not to create a copyright violation. Thanks in advance, Linuxerist L/T 01:14, 14 April 2006 (UTC)

CC-BY-SA 2.0 says that you can use later versions of the same license (CC-BY-SA), so it shouldn't be a problem as long as you license the resulting image as CC-BY-SA 2.5. --Fastfission 04:11, 15 April 2006 (UTC)
Okay, thanks. Linuxerist L/T 11:39, 20 April 2006 (UTC)

Darn search engines[edit]

What is the name of the theory that the act of observing changes the behaviour of the subject being observed? -- Francs2000 01:27, 14 April 2006 (UTC)

I think this is what you mean: Uncertainty_principle but according to that page "The uncertainty principle is frequently, but incorrectly, confused with the "observer effect", wherein the observation of an event changes the event. The observer effect is an important effect in many fields, from electronics to psychology and social science.". Not sure if I completely agree with that statement but there you have it. -Snpoj 01:46, 14 April 2006 (UTC)
Thanks for that. What I was actually looking for was the Hawthorne effect because it applies to social sciences, but your link led me to it. -- Francs2000 01:51, 14 April 2006 (UTC)

male midwives[edit]

how many men are there in midwifery in UK? thanks.robyn

This doesn't look like an especially reliable source, but according to menstuff.org there were 87 male midwives out of 35,000 or so practicing midwives. That's data from ten years ago, though. Isopropyl 03:00, 14 April 2006 (UTC)
Hmm, this site says 10.73% in 2005. Isopropyl 03:02, 14 April 2006 (UTC)
  • How many men in midwifery are there in the other countries of Europe except in UK?thanks a lot.robyn
  • How many men are there in midwifery in some other european countries (except in UK).thanks.robyn
  • How many men are there in midwifery in some european countries, except in UK?thank a lot.robyn
  • How many men are there in midwifery in Finland?in Netherlands? thanks a lot.rob
I'm afraid I know nothing about the subject, but I'd just like to say that 'midwifery' is one of my favourite words. Thank you. Phileas 05:43, 14 April 2006 (UTC)

Invision power board[edit]

Is it possible to export/move an invision power board to another host, either by condensing it to a core file somehow, or using some sort of util? Any response is appreciated. -Tim Rhymeless (Er...let's shimmy) 05:27, 14 April 2006 (UTC)

Please could you clarify your question? It is possible to export the post data from an Invision Power Board to another forum (say phpBB for instance) But to point you towards the appropriate utility you would need to say what forum software you are hoping to resolve your data onto. --Limeyuk 19:43, 14 April 2006 (UTC)

Well, I've been looking at either setting up a new Invision Power Board, or going to phpBB. There's a bit of a constraint on time. I don't know what I'm doing, but I can relay any complicated info onto people that do. -Tim Rhymeless (Er...let's shimmy) 05:02, 15 April 2006 (UTC)

Is this a hoax?[edit]

Has anyone heard of the term isodiasphere (according to the article, describing two nuclides with the same neutron excess) before?

I came across the article while rooting through Wikipedia:Cleanup and am tempted to prod it as an OR neologism (or a subtle hoax, assuming less good faith). The phenomenon it describes seems real if obvious enough, but the term doesn't appear anywhere I can find except Wikipedia and its mirrors. It's not known to Google Scholar, it appears nowhere in the nuclear physics preprint servers, it's not in the index of Krane (ISBN 047180553X), and it doesn't even appear on the site listed as an "external source" by the article.

It's not linked anywhere in Wikipedia except from Chart of Nuclides, and that link was added by the originator of the article (User:Esotericv2), who has no other contributions. But I just thought I'd check with all the knowledgeable people here first. --Bth 07:57, 14 April 2006 (UTC)

I did a search for this term in Chemical Abstracts which contains the abstracts of nearly every publication in the world covering chemistry and the major journals covering physics. It did not locate any mention of that term. --Ed (Edgar181) 12:48, 14 April 2006 (UTC)
Based upon the link for this, I expect it would not be a chemistry term, but one for Nuclear Physics. I did find this link

http://sun.folk.en.ogarnij.info/en/Isodiasphere

Chem Abstracts covers the major journals in the area of nuclear physics, so that shouldn't be an issue. The link you provide is also just a copy of the English Wikipedia article. So still, as far as I can tell, there is no use of this term apart from the article here. --Ed (Edgar181) 14:46, 14 April 2006 (UTC)
I nominated this for deletion. I think it's nonsense. --BluePlatypus 17:42, 14 April 2006 (UTC)

Space-Time Curvature under General Relativity[edit]

stereotypical relativity diagram

This is a question about how non-scientific explanations of the Theory of General Relativity are supposed to explain gravitation. Layman explanations of space-time curvature usually have a diagram (apparently always the same one) which shows a two-dimensional surface streched (downwards) into a third dimension at the location of a body having mass. The story goes that a second body going by with no acceleration will follow a curved path because space-time is curved by the first body.

What I don't understand is why this would cause one body to curve towards another rather than away. When I try to figure out what the curved path will actually be (from the diagram), it looks like the it should curve away. Apparently, it is implied that the second body would fall into the 'depression' in the original two-dimensional surface because of.... what? the influence of gravity? It's apparently using gravity to explain gravitation. How is this explanation supposed to work? The Wikipedia article hints it's not a simplistic as the picture, but doesn't seem to go beyond that.

If someone is able to post a complete and thorough reply to this question, please forward it to the Nobel Prize committee. Seriously, though, the curved sheet model just takes advantage of the fact that objects rolling around on a big sheet in a 1 G field happen to move in a way similar to what general relativity predicts for objects moving past planets and the like. It's meant to show you how things move, not why things move. To really understand why things move, you will have to understand nasty things like metric tensors and the Einstein field equations. -- Filliam H Muffman 07:24, 7 April 2006 (UTC)
Well.. I don't quite see why you'd think it would curve away. If you have a downward "dimple" in a tablecloth or similar and roll a ball towards it, moving in a straight line, it will go around the rim in a curved path once it hits the dimple and continue away in a straight line in a different direction, having been deflected somewhat inwards. That analogy is the point of the picture. If the dimple was raised instead of lowered, then it would be deflected in the opposite, outwards, direction. But gravity doesn't act in that direction, which is why you've got a lowered dimple and not a raised one in the picture. --BluePlatypus 07:54, 7 April 2006 (UTC)
The diagram also gives a nice visual analogy for the inverse square law, since the gradiant of the curve is much steeper near the object than far away. But like the others have said, this is a way of visualizing how the objects would move so, not why. — Asbestos | Talk (RFC) 13:36, 7 April 2006 (UTC)
  • In other words, it's just a cool picture? It's describing the exactly the same behaviour as Newtonian gravitation. Peter Grey
  • Pretty much. It's also meant to give an idea that general relativity deals in spacetime curvature, which, among other things, predicts that light is also affected by gravitation. That makes gravitational lensing possible. Newtonian gravity claimed that light doesn't bend because it's massless. -- Filliam H Muffman 03:03, 10 April 2006 (UTC)
One of the byproducts of Special Relativity has been the famous equation, E= mc², that first stated the fact of mass and energy being only two sides of the same coin, instead of what previous physicists have conceived. While Newton had previously thought light to be massless and thus insupsceptible to gravitation, nonetheless certain details within the mathematical framework he had produced for gravity as a force did predict a certain amount of bending occuring when light approaches gravitational bodies (a third less than what Einstein later proposed), which, although he knew was true, was never able to explain away with his theory. The new definition in modern physics, now, for the word massless, also meant something different. It refers only to those particles with no rest mass, but not necessarily no remaining kinetic energy whatsoever. Due to Einstein's equation, as previously indicated, you may say that light does have mass if you wish to, since its energy could be easily converted to mass via the constant of c². However, the energy of the photon is constantly changing during its flight, so the records for mass you will be able to obtain will never be invariant, thus referred to as the relativistic masss. In modern physics, however, it is no longer considered appropriate to define the particle on terms of its relativistic mass for obvious reasons, and thus it suffices to say that light is massless in the fact that it has no rest mass. Nonetheless, as long as the photon still possessed the kinetic energy/relativistic mass necessary for its existence, then it shall be supsceptible to curvatures in space- time like other particles with rest mass. Luthinya 10:21, 10 April 2006 (UTC)
Erm, where have you got that "third less" from? The Newtonian prediction for the deflection of light around a point mass is half the value given by GR. --Bth 10:34, 10 April 2006 (UTC)

Sorry, got my figures wrong. Thanks for correction. Luthinya 10:45, 10 April 2006 (UTC)

This kind of picture is indeed confusing, but there is another reason for it that hasn't been addressed fully above. The key is the mechanism by which "curved spacetime" affects the motion of objects (particles, satellites, light, whatever). General relativity says that an object moving only under the influence of gravity follows a geodesic in spacetime, which is the analogue of a straight line in Euclidean geometry. Since the spacetime itself is curved, these "straight lines" have properties we do not expect, but they are, in a precise sense, the "least curved" lines you can have within curved spacetime.
Roughly speaking (see below), one of the important properties they share with Euclidean straight lines is that they are the shortest distance between two points. This means you can picture a geodesic in the following way. Take a curved surface, such as the dimpled fabric surrounding the ball in the relativity diagram asked about above, and fix two points, one to be the "pitcher" and one to be the "catcher." We then want to draw the geodesic on the curved surface connecting the two points, representing the path of an object from the pitcher to the catcher. We do this by using a rubber band, stretched taut: this automatically follows the shortest path between the points.
Now suppose we look at the result as viewed from above. If there were no curvature, the rubber band would be a straight line between the two points. Since the ball is there, dimpling the surface downward, the rubber band will not take a path that appears straight as viewed from above, since that path will be rather long due to the dimpling. Instead, the rubber band will curve around the ball slightly, to avoid the trip into the depths of the dimple. When seen from above, it appears that the ball is affecting the path of the object with some "force", when in fact the object is trying to follow the best approximation to a "straight line" that it can in the circumstances.
All that is rather hard to say without additional pictures, hope it comes across. Anyway, very little of that is usually included with the usual picture, which is why it is easy to come to very inaccurate conclusions about what the picture is trying to say. If you want a better version of all this, look at Taylor and Wheeler, Spacetime Physics.
Note for experts: in spacetime, with its Lorentz metric, geodesics are actually local maximizers of proper time; but part of the point of the kind of picture we're discussing is to give a Riemannian picture. --Spireguy 20:12, 11 April 2006 (UTC)
Still, for most layemen beginners, it does offer a much more approcheable beginning for the subject, even if much of the important details have been left out. As far as the geodesic problem is concerned, since we as humans possess four dimensions (including Time), and yet space- time may curve in a way that is impossible for us to conceive or imagine- only "talk about", it immediately shows that space- time curves into at least one more dimension than that to which we are accustomed of in our daily life, i.e. the 4D bodies. And just as the 2D figures upon cardboard cannot stand up vertically upon it, since they have no motion or conception of 'depth', we as 4D people cannot cross the barriers of dimension and traverse into the 5th or other higher dimension freely, as we now have the ability to in our 4D world. We therefore have to kind of traverse with the curvatures of the surface of higher- dimensional space- time, which is to us expressed in a 4D fashion like differently laid card boards are to the 2D beings. Thus, for us, the easiest way between two places in space- time may not necessarily be a straight line, but more usually a curved 4D geodesic adapted from the curvatures of space- time from gravity. Luthinya 20:34, 11 April 2006 (UTC)
That's what I'm getting at. Isn't a path curving away from the point mass shorter? What we would need to visualize would be a contraction of space, not a stretching, right? Peter Grey 04:25, 12 April 2006 (UTC)
Bear in mind that we're measuring "shortest" in the coordinate system defined by the grid drawn on the sheet. The deformations of the sheet deform the coordinate system itself -- that's the whole point of the analogy. What looks longer to us from outside the sheet is shorter, when measured in a system where the side of a "square" on the sheet is a constant however stretched it looks to us. --Bth 11:12, 12 April 2006 (UTC)
The shortest path "in the coordinate system" is the straight line. Or is something still missing in the story? Peter Grey 16:13, 12 April 2006 (UTC)
Um, no. In order to walk the "straight line" in which you are depicting, we must abandon the 4th dimensioned (including Time) curvature of the "surface" of the grid (space- time), and seek to traverse into extra dimensions in order to ignore the curved influences of gravitational objects. However as 4D beings this is pratically impossible for us, so instead of this the shortest route for us will have to be the the curved surface of the grid, which at least is 4D and possible to traverse. Therefore, instead of what Newton has previously proposed, the shortest route between two things is not a 'straight line' in the usual sense of the word, but a geodesic varying according to the shape of surrounding space-time influenced by gravitational fields. At least a longer way is shorter than the impossible, so to speak. The thing is that on the diagram you cannot see the grid curving into extra dimensions the way it should, which is what makes the analogy slightly hard to come to mind. Remember the analogy is only a start to understanding; try eventually to draw away from the picture and just let the ideas flow accross your head- aided by some mathematics, you'll find this much easier.

PS May I add that my above language is extremely inaccurate in depiction, especially without the mathematics to compensate for it. Hope it comes through anyway. Luthinya 18:17, 12 April 2006 (UTC)

  • The point I'm trying to underline is that, unless gravity is assumed (as part of the illustration of gravity), then there is no 'up' or 'down', and the diagram should demonstrate the same behaviour whether the deformation is 'down' or 'up'. Peter Grey
I'm afraid I cannot quite catch your point. What exactly do you mean by down or up? The deformation is curved into extra dimensions for which we may only talk of, yet never be able to obtain direct conceptions of for which we will understand properly since, as I said before, we cannot cross the barriers of dimensions. One should also be careful between the shortest path and the easiest path. Traditionally, we tend to think that the shortest path between two things, usually a "straight line", is also the easiest path to traverse between the two objects in question. However, because of this simultaneous involvement in meaning our brain has got accustomed to thinking that the shortest journey must necessarily be the easiest one to achieve, taking seemingly the smallest period of Time (if you can put it like that). Unfortunately, this stops being true as soon as we step out of the world of the Greek Geometres- the flat world of 2Ds where the curvatures made we can entirely ignore, since we are one dimension (in Space) higher. Already in the 3D world we are encountering trouble. When a tourguide shows you the fastest way to cross a mountain, he shows you the curved path just by the foot of the mountain and fitted to its topological curvatures. However, who would not agree that the shortest way is actually to tunnel through the mountain centre itself, and come upon the other side? True, this may be the shortest way, but it is by no means the easiest. Far easier it is to adapt to the geodesic of the landscape than to delve in it.

Space- time itself possesses more dimensions than our race, so delving becomes completely impossible. All we can do now is follow, once again, the geodesics of the landscape, and trust them to be our easiest way. (or trust maths- whichever)There will be no talk of picking or choosing either- all objects follow intuitively the easiest way to traverse between two points. When there is a stone that curves a rubber sheet downwards the ant naturally walk as close to the stone as possible in getting its way round to the other side, not even waste time climbing or delving into the stone. The same it is for us- we naturally follow the curvatures already made in the fabric of space- time. When a gigantic gravitational body curves space-time into extra dimensions unreacheable, the easiest way to cross to the other side is to the follow the geodesics and walk as close to the body as possible, giving the effect of being "gravitated towards it", rather than away from it where the journey will naturally be harder. Luthinya 09:55, 14 April 2006 (UTC)

  • There seem to be two different answers emerging:
  1. The picture is simply hinting at the connection with geometry. The illustration assumes a vertical force of gravity, and shows geometry causing the attraction to a point mass. That's interesting because it is bridging our intuition about gravity (basically one-dimensional) and attraction to a point mass in two dimensions, but it's also 'cheating' since one force of gravity is being explained using another force of gravity.
  2. The more sophisticated version is that the curvature causes acceleration of a point moving along a geodesic. However, if this is a behaviour due only to the geometry, and there is no assumption of Newtonian gravitation, then there is no up or down, and it's not immediately obvious if a particle in motion would be deflected away from the point mass, or towards it. Peter Grey 19:48, 14 April 2006 (UTC)
  • It seems that we're all talking at cross purposes to one another. Gravity is not explaining gravity; it's illustrating it. These are two very different things, at least to me. -- Filliam H Muffman 00:17, 15 April 2006 (UTC)
I think you may need to clarify what you mean by explaining gravity. The above image shows a simplified visual model of gravitational acts, supplemented to which will be a corresponding mathematical model, along with the verbal analysis itself. These together form collectively what we term as a model of gravitation according to Einstein's Relativity (universally acknowledged as one of the most beautiful models on the subject ever), where instead of understanding it as a force, Einstein chose to interpret it as a curvature in spacetime. In short, as a model was always supposed to be, it is an aid to us in interpreting the results physicists discover throughout their observations in spacetime, and in a way of fitting this into a general system of theories, whereby we have kind of explained why things work the way they do, and how they work the way they do, if you follow me.
But if you wish to explain gravitation in the terms of how it existed "behind the scenes", then I'm afraid not a single human being in the history of creation will ever be able to help you. For all we know, gravitation may just as well not exist behind the scenes, because in being a model of the Nature which physicists try ever so hard to understand, it cannot replace nature for what it actually is. It is only a symbol of Nature, and symbols are different from real existence, merely being a re-presentation of it. Gravitation has been a useful model in attempting to interpret the universe, and by its own terms we have found a suitable fashion of "explaining it" in such a way as we can, yet we can never establish a concept that may capture it as it is "behind the scenes", as it is that -which- is; because, like David Bohm said, no idea can ever capture reality in the sense of that- which- is. It'll be a bit like trying to describe the Tao in Chinese Taoism- utterly impossible except through experience, and that does not describe. After all, reality is not cogi, ego sum, for the simple reason that the concepts and models so important to the human mind are our own hazards and guesses based on what nature would give, but never ultimately nature herself.
So if your question was concerning how one could explain gravitation "behind the scenes", then a thousand Nobel laureates will not be able to help you, even if they all had IQ 180. Einstein once said that the universe was like an unopenable watch, and we who gaze in wonder at its workmanship will begin ourselves to haphazard our way through how it might have worked. But, he concluded, we know that whatever path we may cleave may certainly be dramatically different from how the watch really worked, nor can we even imagine the consequences of such a comparison. Luthinya 10:29, 17 April 2006 (UTC)
  • This is not asking for the ultimate theory of gravitation, but for the justification of the typical picture in non-technical descriptions. "Explanation" is perhaps a poor choice of words. The question is: is the picture assuming a linear force of gravity, and if so, does it have any merit as an illustration of gravity? Peter Grey 15:24, 18 April 2006 (UTC)
Pedantic correction: in Riemannian manifolds (positive definite metric tensor), a geodesic is the shortest curve between any two sufficiently nearby points on the curve. In pseudo-Riemannian manifolds (indefinite but nondegenerate metric tensor), a timelike geodesic arc is the longest timelike curve between two sufficently nearby events on the curve. (Oops, just saw that Spireguy already said that.)
Luthinya wrote May I add that my above language is extremely inaccurate in depiction, especially without the mathematics to compensate for it. Agree with that, unfortunately I must dash what he said next: Hope it comes through anyway. Don't worry, Luthinya, your heart was in the right place.
Peter, I consider your summary inaccurate, except for The picture is simply hinting at the connection with geometry.
I have to say I found this discussion almost incomprehensible, no doubt because precision of expression is so important in a subtle topic and because those who have learned a good deal of gtr share a common background which involves not only mastery of specific mathematical topics like tensor fields but also various examples illustrating crucial distinctions which untrained persons are unlikely to spot, like intrinsic versus extrinsic curvature (failure to distinguish between these is clearly evident in some of the confused discussion above). If I might recommend a nontechnical book: see Geroch, General relativity from A to B. Don't be discouraged by the (not inaccurate) title: if you study this, you will learn a heck of a lot.
One last point: the goal of gravitation physics is not to explain gravitation in the sense many laypeople appear to have in mind; rather physicists hope to model gravitation, even under extreme circumstances. See for example Theories as models. This is why physicists are happy to use Newtonian gravitation unless conditions are so extreme (or measurements so sensitive) that general relativity is required. At some point, everyone expects the advent of well defined quantum theories of gravitation, and these may allow us to model gravity accurately under conditions even more extreme than gtr can handle. We can expect that such a theory will be hard to use, and that it will continue to make sense to use gtr unless we really really need the new theory. Since the way that one thinks of gravitation in Newton's theory, Einstein's theory, and very possibly in yet unknown quantum theories of gravitation are completely different, this clearly shows that physicists are much more pragmatic than laypersons tend to recognize. In popular books, many authors to tend to pander to rather than correct the idea that theories can be simply right or wrong. The truth is far more complex and to my mind far more interesting than that. HTH ---CH 05:28, 21 April 2006 (UTC)

Excel problem[edit]

The default settings for the general format has changed into a percentage. When I start a new excel spreadsheet and type a number (eg 5), and press enter, the number appears as '0.05'. When I go to format cells, it says that the catergory is 'General'. Any idea on how to fix it? It's Office 2003. Thanks all. - Akamad 12:19, 14 April 2006 (UTC)

Go to Tools/Options, Edit tab. Uncheck the "Fixed Decimal" box. --LarryMac 15:15, 14 April 2006 (UTC)
Thank you very much. - Akamad 23:54, 14 April 2006 (UTC)

pepper pad[edit]

Have anyone used the pepper pad? (no, I am not going to buy it, but just want to know about it) I just want to know whether we must have to use the scroll button most often to move left and right? because the screen is just 6 inches wide? or is it enough since we keep the screen horizontally and read? Is the font size small and is a small font size enough since we keep it near our eyes compared to computer monitor?

Life expectancy of LCD vs Plasma HDTV operating 24 hours a day[edit]

I'm looking to upgrade a large scale video surveillance setup with a high definition video wall consisting of 12 - 50" monitors capable of displaying any number of cameras simultaneously, yet have the ability to display one camera streatched across all 12 monitors if I so choose. I cannot justify spending large chunks of budget money replacing LCD or plasma screen TV's every 6 months because either they can't handle being on 24 hours a day, or images have been burned into the phosphorous (LCD) thereby ghosting out the display.

I can hold out for the next generation if need be but I'd buy them now if they could last 2 years (17,500 hours) in that type of environment. I cannot seem to find a spec sheet outlining continuous use...I hope you can

[32] seems to say the industry promises around 20,000 hours of life out of a plasma screen. But it also says that burn in may be an issue. Anecdotally, at work we have LCD screens that are on 24/7 I know of one that has been in place for two and a half years will no ill affects. The image changes regularly though. --Chapuisat 19:25, 14 April 2006 (UTC)

Tree Height - Why Is the Sky Not the Limit?[edit]

Given species and environment, trees reach a peek height. What is it that prevents trees to grow ever taller?

The same reason why humans dont go on growing tall forever... The height depends on the strenght of the tree and a tall tree is no use if it cant stand on its own properly. Jayant,17 Years, Indiacontribs 16:40, 14 April 2006 (UTC)

No that's not it. Humans are genetically designed to grow up to a certain height, and stop growing at a certain age of maturity. Trees don't work that way at all. A tree tends to continue growing until it dies, which leads to another interesting question: Do trees have lifespans? or do they only die of disease or other pathologies?Loomis51 16:40, 16 April 2006 (UTC)

The main reason is not structural consideration but water. You have to get water to the top of the tree. See the cohesion-tension theory. I notice that this article is not that great in wikipedia so you should probably do a google search. In summary, there are a couple of factors that limit the ability of a tree to pull water from the soil to the top. 1) The strength of xylem vessels to with stand the negative pressure creating by "sucking" the water up. 2) the amount of force available from transpiration to pull water to the top of a tree. This is limited by the maximum tension that can be exerted on the water column (determined by the cohesion between water molecules and the adhesion between the water molecules and the inside of the xylem vessel).David D. (Talk) 16:43, 14 April 2006 (UTC)
This is all interesting, and admittedly, much of it I don't understand. Nonetheless, the explanation seems lacking in one main respect: scale. It would seem to me, the larger the tree, the stronger the xylem vessels would be, the stronger the force available from transpiration etc... The only answer I can think of as to why trees don't continue growing forever is that the eventually die, which leads me back to my above question concerning whether or not trees have natural lifespans. Loomis51 16:40, 16 April 2006 (UTC)
Why would it not be a structural consideration as well? (in the evolutionary context) A tall tree has a higher center of gravity and may topple more easily. I don't think there are a lot of evolutionary advantages to being extremely tall. --BluePlatypus 17:33, 14 April 2006 (UTC)
Once again, this argument ignores the relevance of scale. Of course the taller the tree, the higher the center of gravity, but then again, the taller and older a tree is, the thicker its trunk is, thus compensating for the higher center of gravity.Loomis51 16:46, 16 April 2006 (UTC)
Evolutionary advantages 1) Tall trees get access to unlimited sun. 2) Shade out the competition. The reason it is not a structural issue is that the load bearing forces on the wood of trees could with stand much taller trees. Clearly there are structural limitations but in most cases it is the transport of water that is the limiting factor with respect to height. Obviously we could also discuss root architecture (shallow vs deep) and susceptability to wind since this would be more important for some species. Another issue might be if a tree is in a forest or standing alone and soil conditions could make a difference too but i think this is beyond the scope of the original question. David D. (Talk) 18:02, 14 April 2006 (UTC)

Water transport can be accomplished by active molecular pumping at the level of individual cells. If need be, there could be chains of cells passing the water from cell to cell all the way up a tree. Plants do not need to depend on long single columns of water from roots to leaves. However, transport of molecules requires energy. When a tree gets very tall, a large percentage of its energy will be used for transport of molecules. Growth will slow and eventually something will destroy the tree before it reaches "the sky".....structural weakness if nothing else. --JWSchmidt 16:56, 16 April 2006 (UTC)

I'm not sure this is feasible even if there was unlimited energy. This requires diffusion of water through cells and would be too slow. Bulk flow is necessary to move water any distance in a timely manner. Also what active transport mechanisms are available for the movement of water? I thought aquaporins work passively? Are you thinking of some other transporter? David D. (Talk) 20:13, 17 April 2006 (UTC)

With respect to User:Loomis51 argument of scale. Consider if you have to pull water up a xylem and that the weight of the water column increases as the tree gets taller. This is the scale issue where the bioological system breaks down. More weight means more pull is required. More pull means a greater negative pressue in the xylem especially atthe top of the tree. At some point the xylem cannot withstand the negative pressure and air will enter the xylem tube. This is called cavitation and the air will expand massively in the negative presure since there is no cohesion for air molecules. Thus, that particular xylem becomes 'blocked' with air and no more water can move up that vessel. So there is a scale related limitation at the level of the integrity of the xylem vessels. David D. (Talk) 20:26, 17 April 2006 (UTC)

Fair enough, but now I'm curious about my follow-up question. Do trees (or other plants) have natural lifespans? Is it theoretically possible to prune a tree in such a way so that it can live indefinitely or is there some finite limit to how long a tree can live? Loomis51 04:26, 18 April 2006 (UTC)
I think a well managed tree, also known as a hedge, can easily be encouraged to live for a long time. It could subcome to disease but other than that it should be able to keep growing due to the indeterminate nature of meristems and the abundance of meristems (aka lateral meristems). Some bristle cone pines (?) in CA are over 4000 years old. David D. (Talk) 04:48, 18 April 2006 (UTC)
While a single tree may be kept alive through stemming and cloning, any organism that wants to survive the evolutionary race eventually needs to sexually reproduce and then die at some point in time, at least according to the Selfish Gene theory. László 07:52, 21 April 2006 (UTC)

Telephone problems[edit]

There are 2 telephones using my phone line. About 13 hours ago, I picked up the telephone in my room, and instead of hearing the dial tone, I heard "Please hang up immediately and try your call again. This is a recording." I hung up the phone, waited for a few seconds, and picked it up again. I heard the hang-up beeps. I again hung up, waited for several seconds, and picked the phone up. I heard loud beeps, the same beeps that are heard when you don't hang up but the person on the other end did a long time ago.

It seems that a telephone using my phone line is not hanging up. But there are only 2 telephones connected to the phone line, and nobody was using the telephone not in my room.

As of now, when I pick up either phone, there is no dial tone but only a low buzzing noise. This noise is similar, though a bit louder, than the sound you hear during a successful call but when nobody is speaking.

What is likely the cause of these problems? Why did another phone line, used by the family sharing my house, fail too? I'm guessing that the problem is with the place where all the phone lines meet (in a "control panel" in the basement), since both lines failed nearly simultaneously (but the other one works now--my line still doesn't). --Bowlhover 18:17, 14 April 2006 (UTC)

I suggest there may be a problem with one of the phones. Disconnect them both, take a nap then connect one and see if it works. If it does, connect the other one and see if both work now. Your comment that the other phone line also failed suggests the problem may be the control panel in the basement like you thought.
Oh, Bowlhover, what have you been doing to draw the CIA's attention to yourself? (heads off in search of tinfoil hat) --Bth 18:41, 14 April 2006 (UTC)
LOL, I also suspected the problems might be because of a wiretap. But which wiretapper leaves their device on for hours, preventing their "victim" from making phone calls? Anyways, my phone line works now--I don't know why, and I don't know when it started working. --Bowlhover 23:42, 14 April 2006 (UTC)
This is not very common with phones. It is an old modem problem - the modems can connect, but they fail to disconnect. By chance, do you have a computer also plugged into the line? As for the sounds, they are common. The first message is a pre-recorded message that tells you to hang up. The next is a loud beep to get your attention. Then, the line is disconnected at the phone company's end and you get nothing by static. --Kainaw (talk) 18:48, 14 April 2006 (UTC)
No, none of the computers in my house are connected to a phone line. Also, it's not a loud beep I hear after the recorded message--it's a series of beeps that you get every time the person on the other end hangs up, followed by another louder series of beeps telling you to hang up immediately. --Bowlhover 23:42, 14 April 2006 (UTC)
Your lines are buggered. Time to haul out the old phone and call the phone company. I had a problem with my phone broadband. Turns out that when the house was renovated, the bell wires had been folded over from one end of the house to the other. We had to put in a new straight line, since DSL hates folds.--Zeizmic 13:15, 15 April 2006 (UTC)
Something was obviously holding the line open, could have been a line fault, could have been one of the phones, could have been a poor attempt at a wiretap as has been suggested. If it happens again try the phones seperately. If that fails borrow another phone to try and if that fails its time to look at the wiring. Plugwash 00:35, 20 April 2006 (UTC)

Is Oxygen poisonous?[edit]

O^2, more precisely. I've been told that it is actually poisonous and the information about oxygen poisoning here on Wikipedia doesn't explain how it occurs very well so I'm rather confused about it. Also, is it possible to live on pure oxygen or are the other elements of air necessary for a human to respirate?

Everything is poisonous in large enough quantities. The concept of 'poison' is basically to do with the quantity. People need it, but can have too much of it. Do you have some specific questions about the oxygen poisoning article? For great justice. 20:48, 14 April 2006 (UTC)
You can live in an atmosphere of pure oxygen, but bad things can happen -- Apollo 1
The 'poison' concept means that free oxygen is poisonous within the body. That is why great pains are taken to encapsulate oxygen with iron - Hemoglobin. --Zeizmic 20:52, 14 April 2006 (UTC)
  • "Poison" means "too much" more than "this is poison and that isn't". Vitamin A in tiny quantities will kill you and in even tinier quanties is necessary. Everything if taken in sufficient quantity is poisonous.
  • At low pressure, like is used at high altitudes and in space, 100% oxygen is fine. No other gas is needed by the body
  • The higher the pressure (the deeper in the ocean of air or water you are) the less time one can breath a given percent of oxygen. To not be poisoned by oxygen when deep sea diving the time must be short or the oxygen reduced in percentage. WAS 4.250 21:15, 14 April 2006 (UTC)
Oxygen is poisonous to certain bacteria that evolved before there was oxygen in the atmosphere. This group of bacteria is called, for obvious reasons, "anaerobic bacteria". They only live in closed spaces, like in deep wounds. For them, hydorgen peroxide, which releases oxygen, is poison, ie a "disinfectant". So what is poisonous to a given species , like possible extraterrestial species, depends on the paritcular biochemistry of that species. GangofOne 21:26, 14 April 2006 (UTC)
My understanding is a small quantity of carbon dioxide is necessary to keep a person breathing. Buildup of CO2 is what triggers respiration. In an atmosphere of pure oxygen this does not happen and a person will pass out.
No, the body creates it own CO2. WAS 4.250 21:33, 14 April 2006 (UTC)
My understanding was the CO2 in the body would be liberated in a non-CO2 atmosphere so fast the respiration would slow down and thus, less CO2 would be generated. This would result in a vicious circle sort of situation.
CO2 in the atmosphere (compared to your lungs) is already very low, removing it completely would not increase the concentration gradient by that much. Also, the CO2 is a result of metabolism in the cells so its production would not slow down if there was less CO2 in the lungs.David D. (Talk) 22:16, 14 April 2006 (UTC)

Breathing oxygen can be poisonous to humans.

This is probably caused by the excess production of superoxide, a highly reactive molecule with a free electron which can interact with other cellular molecules and distort or destroy them. One site where these superoxides are formed is in the mitochondria, the power production plants of eukaryotic cells. It is estimated that, in normal cicumstances, up to 5% of oxygen flowing through a mitochondrion can end up as superoxide, instead of being incorporated into the the normal end products of glucose metabolism, carbon dioxide and water (aerobic cellular respiration).

Superoxide combines with other cellular molecules to form reactive oxygen species or free radicals (these two are not necessarily the same), which are also highly reactive.

The problem with free radicals is that they typically cause chain reactions, i.e. superoxide damages molecule A, which becomes a free radical and damages molecule B, which becomes a free radical and damages molecule C, and so on. Fortunately, these harmful free radicals would normally be inactivated by enzymes such as superoxide dismutase and catalase, and any damage done is usually repaired before the body suffers. They are never the less implicated in the process of ageing.

In the case of oxygen toxicity, or poisoning, an increased flow of oxygen through the mitochondria leads to an increase in superoxide. A high enough increase for long enough, can cause superoxide levels to become so high that the free radicals and the resulting chain reactions cannot be held in check by the normal cellular countermeasures. The proteins, fats and even the genetic molecules (DNA and RNA) of the cell are damaged, and the cell loses its normal function, or even dies.

Two effects are most prominent:

1. The lungs become stiff, congested with fluid and inflammatory exudate, and eventually scarred, so that it becomes difficult to breathe and oxygen cannot get through to the to the blood in the pulmonary capillaries (respiratory distress syndrome). This is caused by direct cell damage and cell death, as well as changes in production of surfactant. It can be permanent and cause death.

2. The person develops fits, identical to grand mal epileptic fits. This could be due to damage to cells as such, with swelling and generalised disfunction, or to alterations in nerve transmission – either changes in neurotransmitter release or changes in the receptors for those substances. As in epilepsy, fits can cause further brain damage, physical injuries or breathing problems associated with loss of consciousness.

In humans, symptoms and signs of oxygen toxicity usually occur only after breathing oxygen with a partial pressure of greater than 60 kPa for 24 hours or longer (lower concentration are probably safe for very long periods). The higher the partial pressure, and the longer the exposure, the more the damage done.

Damage to the lungs can occur with ordinary supplementary oxygen use in hospitals, when more than 60% concentration is used for extended periods, while fits are more commonly seen under hyperbaric (high pressure) conditions, such as is encountered in deep diving or in hyperbaric chambers.

In premature babies, high oxygen concentrations are associated with damage to the eyes (retinopathy of prematurity), which can lead to blindness. There are probably more risks to the babies’ health, such as protracted lung problems and even an increased incidence of leukemia, but these have to date not been precisely defined.

Note that free radicals and reactive oxygen species are essential for normal functions. They are for instance used by the body to destroy bacteria, or for cellular signalling, so that they are in themselves not “bad”. It is the excess that harms.

Humans do not need any gas other than ogygen to respirate. Specifically, we do not need to inhale any carbon dioxide. However, if one breathes completely dry gas, especially if the gas bypasses the nose, respiratory secretions tend to dry out and thicken, increasing the risk of infection or plugging of airways in the lungs.

Seejyb 20:00, 15 April 2006 (UTC)

April 15[edit]

Animals and Babies[edit]

Do animals think like we do? Is it possible that back long ago animals used to talk? Do babies think like we do? I mean like if they are eating bananas at the age of one and don't know how to talk might they be thinking about how they hate the banana?

Category:Animal communication? Melchoir 02:00, 15 April 2006 (UTC)
Oh, and Category:Developmental psychology. Melchoir 02:07, 15 April 2006 (UTC)

Humans don't even think like one another. WAS 4.250 03:13, 15 April 2006 (UTC)

Most animals would definitely not think like we do. In fact it was recently proven lobsters are not evolutionarily developed enough to nocicept. However, animal lovers are frequently completely sure that their dog is feeling lonely, happy, or confused. It is a common tendency for people to think of inanimate objects as having human-like characteristics, in fact it is inherent, and one of the most basic ways of learning. A baby copies what its parents do. I can't find the link, but there is an article on here somewhere about different levels of emotion. Primary emotions are like fear, and contentness, the most basic. Secondary emotions are more complicated, and include confusion, and depression. -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 05:11, 15 April 2006 (UTC)
I sort of feel compelled to point out that animals aren't "inanimate objects", and that it's well-known that animals have emotions. It's also quite clear that lobsters are capable of nociception: the question that remains open to debate is to what extent that nociception is accompanied by emotional distress. The idea that humans have emotions and animals don't is, frankly, rather silly from an evolutionary standpoint. Our emotions didn't spring from nowhere, and emotions have been quite clearly described in various animals. - Nunh-huh 09:07, 15 April 2006 (UTC)

I think the word 'emotion' is not helping us here: to me it implies things like love, or anger, which I very much doubt (other) animals experience. If we can agree that my cat is not as emotionally developed as me, but that it does have some form of consciousness, then the only uncertainty is as to the degree of difference. My best guess is that my cat can experience distress, contentment and pleasure, all of which I think are induced by physical stimuli of one sort or another, rather by feelings of love for me or hate for the neighbour's cat. I doubt that animals get much more emotionally developed than that, though I haven't met many gorillas or whales. I'm quite sure that some animals are less developed. HenryFlower 11:22, 15 April 2006 (UTC)

Linguists don't have a definite consensus, but one theory holds that the language faculty is principal difference between humans and other animals, and language is the fundamental medium of human thought. Animals, even those with communication, do not have the language faculty, and infants less than two years have only a rudimentary language ability. So although they might learn an association between a food and negative emotions, they could not be thinking about how they hate in the normal sense of 'thinking'. Peter Grey 11:39, 15 April 2006 (UTC)

  • Francis Galton once wrote an article about why dogs were so great as pets -- they seem to have very similar emotional faculties as humans, and as such we can understand them pretty easily (it is easy to tell when a dog is happy, sad, angry, excited, hungry, bored), and they can understand us pretty easily (they understand tone of voice, facial expressions, they can tell when we are unhappy, etc.). He then, quite humorously, alluded to the fact at how rare this is, with a line something along the lines of "Who ever imagined shooing away a mosquito with a disapproving look, or pacifying an angry wasp with a winning smile?" In any case, with emotions in man and aninmals, I don't think one can draw too many really hard-and-fast difference between the two as categories go, with the only potential instance being language, but even then I am not sure the verdict is in on whether or not certain forms of communication amongst animals don't involve some sort of language faculty or not. --Fastfission 18:30, 15 April 2006 (UTC)

I would say that some animals exhibit all the emotional range of humans, with other primates being the closest. Even some single celled animals appear to exhibit fear and aggression. However, symbolic logic seems to be almost exclusively human. That is, the ability to think in words is not shared by animals. Some people with delayed language skills can likely recall what it's like to think without words. A series of pictures is sometimes how it's described. For example, Helen Keller didn't learn to speak sign language until later in childhood so would have recalled thinking without words, as animals do. StuRat 22:01, 15 April 2006 (UTC)\

I agree with that. The ability to describe or express a feeling is what turns a feeling into an emotion. I would say that only humans have emotions, because only humans have language, but most sensate beings (including plants) are known to have feelings (which we tend to refer as 'instincts' in the case of animals). JackofOz 02:11, 16 April 2006 (UTC)
I disagree. According to your def, Helen Keller had no emotions until she learned how to sign. I also disagree that plants have feelings. StuRat 09:01, 20 April 2006 (UTC)
OK. Scrub the "plants have feelings" bit for now (although I'm amazed we don't have an article on Cleve Backster - he's certainly become notorious in the scientific world, which in my view qualifies as notable).
But yes, Helen Keller did not have emotions until she learned to sign. Of course she had feelings, and of course she knew what those feelings meant to her even if she couldn't articulate them to another person (or even to herself). But that, in my understanding of the words, is what differentiates a feeling from an emotion. People tend to use the words interchangeably, but I think this is a mistake. JackofOz 10:24, 20 April 2006 (UTC)
Do you have a source for your def: "The ability to describe or express a feeling is what turns a feeling into an emotion" ? StuRat 00:29, 22 April 2006 (UTC)

Drug Ratings[edit]

I work at a pharmacy and sometimes when I read pharmacutical magazines, I notice it say "AB rated" on some of the drug advertisements. I think there are other ratings also, but I can't remember. What does it mean? —Preceding unsigned comment added by 68.171.53.125 (talkcontribs)

Those are Therapeutic Equivalent Evaluation Codes that are used by the FDA to denote therapeutic equivalence to other pharmaceutically equivalent drug products. A drug which is AA-rated or AB-rated to another indicated that they are considered interchangeable by FDA standards and can be substituted unless the physician designates otherwise. Sometimes a number is appended (AB1, AB2, AB3, etc). Another designation, BN-rated, means "not equivatlent". see [33] - Nunh-huh 04:54, 15 April 2006 (UTC)

Organ[edit]

Which of our organ, distributes the nutrients which we (humans) gain from the digested food, to different parts of our body according to their needs?

  • The majority of digestion and absorption takes place in the small intestine - where the acidic broth from stomach is completely digested. Polymers such as proteins, polysaccharides, nucleic acids, and lipids are broken down into their monomer components by hydrolytic enzymes. These monomers are then absorbed through the lining of the small intestine into capillaries. These capillaries drain into the hepatic portal vessel, which drains into the liver. The liver has the metabolic versatility to interconvert various organic molecules, so the blood that leaves the liver has a very different composition than the blood that enters the liver. Wapatista 08:52, 16 April 2006 (UTC)
But the thing about the question that struck me was that the questioner seems to think there might be an organ overseeing appropriate distribution of nutrients, and there isn't. To some extent, the body has an ability to preferentially "feed" the brain on the basis of producing fuel preferentially used by the brain, but otherwise it's pretty much a case of every organ for itself. - Nunh-huh 09:01, 15 April 2006 (UTC)
Per Dalembert's comment below, the body does have at least some ability to regulate the delivery of nutrients and oxygen to different tissues and organs through manipulation of the cardiovascular system. Certain triggers (a shortage of oxygen, a spurt of epinephrine (adrenaline), heat or cold, etc.) can trigger the constriction or relaxation of blood vessels and changes in heart rate, regulating the amount of blood reaching particular parts of the body. There's no single organ that controls the cardiovascular system, however; it's a complex system that responds to a lot of different inputs. To name a couple, blood pressure is regulated by baroreceptors mostly in the aorta and the carotid arteries; epineprine comes from the adrenal glands that sit on top of the kidneys. TenOfAllTrades(talk) 15:57, 15 April 2006 (UTC)
So the body parts control delivery of nutrients by consensus :) WAS 4.250 16:22, 15 April 2006 (UTC)
  • In a sense it is the liver, as it alters blood composition to what it is standard and therefore utilised in the body. It is also the circulatory system, as this distributes nutrients throughout the body. And in some sense it is the various organs of the endocrine system, as this releases hormones throughout the body responsible for regulating metabolism and uptake of materials by cells. Wapatista 08:52, 16 April 2006 (UTC)

The literal answer to the question, though, is simple: it is the cardiovascular system that distributes nutrients to all the parts of the body. Dalembert 14:26, 15 April 2006 (UTC)

People, look at the question. Which organ distributes nutrients to different parts of the body? Not "allocate" or "regulate" or "parse out", but simply "distribute". No debate here. Nutrients get from one organ to another in the blood, propelled by the heart. Period. Cardiovascular system is the only, literal, single correct answer. As much as I respect the liver, brain, and endocrine system, the blood flows for a purpose, and transport of nutrients, gases, and signals is that purpose. alteripse 12:16, 16 April 2006 (UTC)

"According to their needs" - the cardiovascular system isn't involved in regulation, so it's worth mentioning the other organs that do this, and also helpful to build up the "bigger picture". Although you are right. Wapatista 13:07, 16 April 2006 (UTC)

Physiological differences between white and red muscle[edit]

What are the differences between white muscle, for example, fish and bird muscle, and red muscle, for example mammal muscle? i've never come across a satisfactory answer for this question. My basic assumption is that it has something to do with blood supply to the muscles, and if so, how does this relate to function of the muscle? Wapatista 07:38, 15 April 2006 (UTC)

Muscle fibers come in different varieties. One, called the fast fibre, fast twitch fiber, Type II fiber, fast-twitch glycolytic fiber, or white muscle fiber, contracts quickly after nerve stimulation. They result in powerful contractions, but they fatigue rapidly because they contain few mitochondria. Another, called the slow fibre, Type I ffiber, slow-twitch glycolytic fibre, or red muscle fiber, contracts three times more slowly, but they fatigue less easily because they contain more plentiful mitochondria, and extensive capillary supply, and myoglobin.
Most muscle contain both types of fiber, but they are in different proportions. In animals that have "white meat", the type I fiber predominates; in those that have "red meat", the type II fibers do. - Nunh-huh 08:57, 15 April 2006 (UTC)
The article corresponding to what Nunh-huh is saying is muscle fiber.-gadfium 09:13, 15 April 2006 (UTC)
Thanks a lot. Wapatista 08:54, 16 April 2006 (UTC)

Properties of PVC[edit]

I am looking for a (simple) table/explenation of the physical properties of PVC (PolyvinylChloride). Thanks. —The preceding unsigned comment was added by 203.122.88.32 (talkcontribs) .

Polyvinyl chloride. You see, there's this search box on the page, and there's somewhere else on the page that says ... oh, forget it. Confusing Manifestation 11:01, 15 April 2006 (UTC)
Maybe someone could make a template to automatically suggest a search so it doesn't need to be typed it out manually in the future? --Username132 (talk) 01:53, 16 April 2006 (UTC)

embedded systems[edit]

what is the ato —The preceding unsigned comment was added by 202.65.149.74 (talkcontribs) .

Possibly the Australian Taxation Office? Or the Agricultural Trade Office? In Japanese the ato is the time after now!  freshgavinΓΛĿЌ  06:22, 17 April 2006 (UTC)

Which tablet PC?[edit]

I am buying a tablet PC. I use the computer all the time to surf the net and also read news. I prefer to use the tablet like a slate and read because that is comfortable for me compared to using it like a laptop. What size tablet should I buy? If I buy a 10.4" tablet, will it be too small to browse the web? (Note here that I plan to use it in the slate format and not like a laptop). Or will a 10.4" be good enough size to browse websites? Should I scroll frequently in a 10.4" tablet to read pages? Or should I try 12 inches?

I would say you need excellent eyesight to make out a reasonable amount of text at 10.4 inches. I suggest you test it out on a few of your favorite websites before buying it. StuRat 19:12, 15 April 2006 (UTC)

Convert HTML to JPEG or GIF[edit]

Can I Change The Whole Internet Page (HTML) To Picture Format (JPEG or GIF ) ?

Well, you can certainly take a screenshot or your browser window. I suppose, if the page is too long, you can scroll down and take more screenshots and stitch them together in a paint program. There may well be programs that can automate this process, but if you only want to do this for one or two pages, this might be the simplest solution. —Ilmari Karonen (talk) 20:01, 15 April 2006 (UTC)
Another solution might be to print the page to a file, open the file in a paint program, and save it in whatever format you like. Of course, this assumes your paint program can read whatever format the "print to file" option produces on your computer; if you're lucky, it's PostScript, if you're not it's some proprietary printer-specific format. —Ilmari Karonen (talk) 20:05, 15 April 2006 (UTC)
You can do this easily with Ulead Photoimpact. Just open the page and then export it to an image file. -Halidecyphon 20:49, 16 April 2006 (UTC)

One may also simply print/export as a pdf file and open in photoshop or photoshop elements. 70.183.234.163 17:38, 20 April 2006 (UTC)Thisdude415

C++ cin stream failure[edit]

Imagine I write the following as part of main():

int n = 0; cout << "enter a number please: "; cin >> n;

And compile and run the program. Everything works great unless the user types in a letter, in which case the cin stream fails and the program ignores any further attempt to use cin.

How do I get around this problem? Thanks, JD --128.248.77.71 21:14, 15 April 2006 (UTC)

There are several things you can do, depending on whether you just want to detect the condition or recover from it. Take a look at [[34]].-gadfium 00:19, 16 April 2006 (UTC)
cin is an istream, it is reading input up until white space. Once it reads a letter, it is in an error state; you clear it with cin.clear(). But what you probably need is more sophisticated input parsing. Peter Grey 12:17, 16 April 2006 (UTC)
Simply using cin.clear() is not enough, as the letter typed is still in the input buffer and the problem just reoccurs with the next attempt to read a number. You therefore need to both clear the error condition and read the unwanted characters into a throwaway buffer, or else use cin.ignore(...) to get rid of the letter(s). The link I gave above explains this much more clearly than I could do.-gadfium 20:20, 16 April 2006 (UTC)

eMule causes DNS failure[edit]

Can anyone tell me any hint of why this is happening? It only happens in Windows, in Linux it's fine.

Specifically, I bet you have a Netgear ADSL router. I've seen several cases where eMule seems to "fill up" the DNS tables inside a Netgear router, which can only be fixed by rebooting the router. -- Finlay McWalter | Talk 23:59, 15 April 2006 (UTC)

Thanks ;)

If thats the problem then bypassing the routers dns server and setting your machine to talk to your isps servers directly may bring a fix. The dns proxies in home routers seem to be fairly poor in general. Plugwash 01:01, 22 April 2006 (UTC)

learning Computer language[edit]

I am not trolling. I need to learn a 'computer langage' by August or I am vegetable. Please help me!

Situation: I have no previous experience with computer language. (And pleae don't tell me to learn QBasic, my sister does not count it as a computer language.) I need to learn a new language from scratch and I have heard about Python, Perl, FORTRAN (my dad used it but I don't want to nag him all the time) but I have not used any of these. Please also recommend me some free good pdf books online. Thank you.

Yours sincerely, Kushal Hada [Four tildes] Kushal one 23:41, 15 April 2006 (UTC)

Bruce Eckel has freely downloadable books teaching programming in C++, Java and Python. His books on the first two are probably not suitable for someone who has absolutely no programming experience, but I haven't looked at the last. Your choice of language should depend on what you need to use it for; if you explain why you need to learn one we may be able to help more.-gadfium 00:29, 16 April 2006 (UTC)
This issue has been discussed here before, see Wikipedia:Reference_desk_archive/Science/March_2006#Learning Computer Programming. I might add, that despite what your sister might say, QBasic is a completely valid programming language. In fact, any program that can be written in a particular language, can also be written in any other language, as long as they're Turing complete (most are, including QBasic). In fact, I would recommend starting with QBasic or C, then move on to an object-oriented language, such as C++ or Java. Of course, you can also choose the path of functional programming, and learn Scheme. It really depends on what you need to use the language for, if you're going to be writing simple things for an embedded system that you created, you might as well just start with an Assembly language, and not bother with any higher-level ones. --Aramգուտանգ 00:37, 16 April 2006 (UTC)
A pretty simple language which is also quite powerful is PHP. You can learn the basics of it in a few hours if you run through a few tutorials. It is pretty straightforward as far as scripting languages go. --Fastfission 17:09, 16 April 2006 (UTC)

Start with Pascal programming language. It was designed as the language to use to learn how to program. After you read the just mentioned wikipedia article on Pascal, read [35] and use [36]. WAS 4.250 17:21, 16 April 2006 (UTC)

Java 2 is currently one of the most powerful languages available on computer programming. It is not too difficult as long as one is willing to think. I'll recommend the book I used :Java 2 In Easy Steps by Mike McGarth from the "In Easty Steps" series. Luthinya 10:34, 17 April 2006 (UTC)

I can program in Perl, PHP, Python, Bash, Javascript, and Ruby, yet I have tried repeatedly to learn Java without any success. While it may be easy for some, it's certainly not for all. If I was to recommend a programming language for someone just starting to learn, without all the weightiness of other languages, it would definitely be Ruby. --Kickstart70-T-C 22:46, 21 April 2006 (UTC)
Afaict there are 3 basic approaches to learning programming all with thier pros and cons.
1: start simple, e.g. start with a language like basic or one of the scripting languages. Easy to get started but the habbits you pick up may set you in bad stead when you move onto more serious languages. (the poster above seems to be an example of this, he's picked up a load of scripting languages but is having trouble moving on from there to more serious stuff)
2: start well structured, e.g. with a language like pascal or possiblly java (starting with java creates gc addicts though which is not something i wan't to encourage). Such languages force you into learning good structural habbits early but may have a steep learning curve.
3: start low level. e.g. start with assembler (NOT i386 assembler though if you value your sanity). The big advantage with this approach is that you learn what can be done in few instructions and what can't. This will stand you in good stead to write well performing code as you move on. If your going this route i'd reccomend getting a pic18f452 board to experiment with. Plugwash 01:09, 22 April 2006 (UTC)

April 16[edit]

Ice age[edit]

Here it says how the three main causes of ice ages are: The earth's orbit around the sun changing; the atmosphere changing; and the "arrangment of the continents". I heard how scientists say there will be another ice age in about five million years from now. How do they know that? Jonathan talk Flag of Canada.png 00:40, 16 April 2006 (UTC)

They are estimating based on the past. They find evidence of changes in Ice cores and from those changes they try to predict what is likely to happen. Admittedly, the "arrangement of the continents" reason sounds suspicious. I will have a look at that one. The orbit around the sun can be predicted with a very high degree of accuracy, and its effect on the amount of heat the earth receives, and the rates at which it receives the heat will affect when the next ice age will occur. Ansell 00:58, 16 April 2006 (UTC)
The arrangement of the continents is very important. The arrangement of land is relevant as it affects the circulation of the oceans, which has a strong modifying effect on climate - ice ages are far more likely in some continental arrangements than others. It only sounds like an odd reason because we normally think of "The Ice ages" as occurring only in the last few million years, during which time the continents have been roughly in the same places - but they've actually been going on intermittently for hundreds of millions of years. Sometimes there are long periods with no ice ages or long periods with many ice ages - the reason for these two distinct climatic histories is the positions of the land masses. Grutness...wha? 01:32, 16 April 2006 (UTC)
A follow-up to that from the BBC... [[37]] Grutness...wha? 04:59, 22 April 2006 (UTC)

While I have no doubt that a significant change in the Earth's orbit could cause an ice age, what makes them think the Earth's orbit has ever changed significantly ? StuRat 23:36, 17 April 2006 (UTC)

Thanks for all the answers. (Does anyone think my signature is ugly?) Jonathan talk Flag of Canada.png 14:23, 18 April 2006 (UTC)

I do (at least the name part, the Canadian flag is OK). StuRat 09:11, 20 April 2006 (UTC)

black people[edit]

Do they tan or is their skin always the same color? A Clown in the Dark 01:47, 16 April 2006 (UTC)

Sun tanning is simply the skin activating chemicals that are already in our skin. People who have those compounds activated because of their genes, may get slightly more tanned, however, I am not sure it would be easy to tell the difference as their extra level of activation may be very minor. Ansell 02:48, 16 April 2006 (UTC)
Black skin is not, however, immune to burning, and more to the point, it's not immune to skin cancer (though it less prone to certain types of skin cancer than lighter skin.) --jpgordon∇∆∇∆ 02:58, 16 April 2006 (UTC)

Yes, black people tan. WAS 4.250 17:32, 16 April 2006 (UTC)

They are susceptible to tanning and burning, and the effect can be just as dramatic as in whites. Bhumiya (said/done) 21:22, 16 April 2006 (UTC)

Though, as one would expect, it's much easier to notice the difference in a 1% shade to 11% shade change than a 30% shade to 40% shade change. In other words, your big fat white Uncle Al would look quite a bit more rediculous with a light burn than your dark muscular Aunt Franco.  freshgavinΓΛĿЌ  05:20, 17 April 2006 (UTC)

Yes, they do tan, though the effect is considerably much less noticeable because of the high melanin level found naturally in their skin in the firs place. Luthinya 10:36, 17 April 2006 (UTC)

Drive Arrays In Proliant 3000[edit]

Since linux doesn't treat my HD very separately and treats them as one big 'hda', what does that mean if one drive fails on start up?

Similarly, if I erase my server and treat the drives as one big "logical drive" does that enhance risk of data loss in the event that one drive fails? Would they be better all as separate logical drives? Also, what is the meaning of a an array - why are my logical drives arranged under the umbrella of an 'array'?

I would like to make use of the maximum amount of space with the minimum risk of failure which I think is RAID 0, all HDs treated separately. Also, why if one drive fails, should the server demand that it is replaced before starting up? Even if it is replaced, the data isn't going to be there...? --Username132 (talk) 01:50, 16 April 2006 (UTC)

Maximum space doesn't go with minimum failure. You choose which one you are more worried about and go with that. I would personally choose RAID 0 for speed, but with the knowledge that because it is one logical drive, if one fails, there is no backup. However, if you want minimum failure, look at RAID 1, where you get everything put down twice on separate hard drives so if one fails you can still use the other one.
Linux only treats them as one big hda if they are all put together in RAID, or if you are using Logical Volume Management, or any of the alternatives. If you put two non-RAID hard drives in Linux is likely to assign one the hda and one the hdb, unless they are SCSI in which case they will be sda and sdb.
If one drive in a RAID 1 array fails on startup nothing bad happens, your computer will boot as normal. However, if you have RAID 0, you have just lost half of the data on your computer. Ansell 02:44, 16 April 2006 (UTC)
Well I want to use 8 (18.2 GB) drives. I figure I could split this into two logical arrays - one consisting of a single HD for the OS(es) and another for storage. But if 7 drives are in one logical drive does that mean that they're all one partition? I the logical drive entry doesn't explain what would happen if one drive failed? Would I be better off having 8 logical drives or the two like I just mentioned?
If you have a large number of drives your best bet is RAID 5 - this will strip data across multiple drives, but will add a parity drive so that you have one level of redundancy - a failure in any single drive will result in no loss of data. As you add drives your chances of having a failure go up - with seven drives you are definitely in a high-risk position with RAID 0. With RAID 0 your space available is the sum of all drives. With RAID 1 it is the size of one drive. With RAID 5 it is the sum of all drives minus 1. Performance of RAID 5 is less than RAID 0 or 1, but better than single drive performance. Raid can be implemented both in hardware (which is common on server-class hardware like a Proliant), or by software (LVM, etc). Rich0 12:37, 23 April 2006 (UTC)

When did RAID come into existence? The computer I'm referring to is about 8 years old and uses hot-pluggable SCSI drives in their own little caddies. When I use Compaq SmartStart to configure 'the array', it invariably wants to put them all into one big logical drive and the "array condiguration utility" gives me a graphic kind of like this;

Controller
    |
   Array
       |
       Logical drive 1
       Logical drive 2

What's this array nonsense? I don't want any arrays... :( --Username132 (talk) 03:43, 16 April 2006 (UTC)

See Redundant array of independent disks for history and more. Servers such as yours have had RAID controllers for long, it seems, but common PCs/Desktops generally only for the past 3-4 years. Max space / Min failure would seem at it simplest to correspond to a RAID 1 setup, 2 logical drives of 4 identical physical disks each = 100% duplication. --Seejyb 14:06, 16 April 2006 (UTC)

P2P Malware[edit]

If you download a linux distro from a p2p network, couldn't someone have altered the code to add some malware and control your computer remotely? --Username132 (talk) 02:16, 16 April 2006 (UTC)

Depends on where you got the source from. If you get the link from the distro's website, then no it's fine.

You can run md5sum on the downloaded file and compare this to the sum that is given on the distro's website to confirm that your copy has not been tampered with. They may even have digitally signed the file and you can confirm it that way as well. Ansell 02:38, 16 April 2006 (UTC)
Thanks :) --Username132 (talk) 03:28, 16 April 2006 (UTC)

Forum on IMDB working?[edit]

Here is a link to the [Chinatown (1974) entry on IMDB. The forum links aren't working for me. How are they for you? -Username132 (talk) 03:44, 16 April 2006 (UTC)

Did you register? Going to the message board came up with a "Free Registration" window for me, but I don't see the need to give away my details, so i didn't proceed. The user comments were working for me. Is that what you meant? Ansell 04:47, 16 April 2006 (UTC)
Yeah, I'm registered. It even gives my login name in the top right, but when I click on the link to go to a forum (not comments), the browser load bar appears and then makes no progress... indefinately. Thanks for trying anyway. --Username132 (talk) 04:57, 16 April 2006 (UTC)
I'm having no trouble with the link. I'm registered with IMDb, and I went to the main movie page, the main forums page for the movie, and the top topic in the forums list with no problems. Was it perhaps a particular thread that you were having trouble with?--Anchoress 11:38, 16 April 2006 (UTC)
It was a whole forum that wouldn't work. Couldn't get to the forum, or the selected threads on the main movie page. It's spontaneously resolved now, but I don't know why. --Username132 (talk) 18:29, 16 April 2006 (UTC)
I frequently have problems with imdb where it loads a blank page and stops, and I have to refresh to get the info to show up. User:Zoe|(talk) 21:31, 16 April 2006 (UTC)

Statistics - type 2 error (oh noes!)[edit]

According to false negative;

"In statistics, a false negative, also called a Type II error or miss, exists when a test incorrectly reports that a result was not detected, when it was really present. (Alternatively, a Type 2 error can be thought of as a failure by accepting the alternative hypothesis when the null hypothesis was truly false.)"

So what it says at first is that a type 2 error is accepting the null hypothesis when the alternative hypothesis was correct? And then it contradicts itself by saying alternatively, a type 2 error is accepting the alternative hypothesis EVEN THOUGH the null hypothesis is actually wrong? Putting the word 'truly' before false is also stupid. I'm changing it to 'actually'... -Username132 (talk) 04:54, 16 April 2006 (UTC)

The "clarification" inside parentheses is wrong! A type 2 error is an erroneous rejection of the alternative hypothesis. (In other word, the null hypothesis is false but one fails to reject it.) --68.238.254.236 15:20, 16 April 2006 (UTC)

How long before a feral animal becomes a native?[edit]

Hey people. I was wondering if there was a hard and fast rule in place about how long a species of feral animal has existed before it is referred to as a native. For example, the dingo was introduced to Australia about 15000 - 30000 years ago and today is generally considered a native animal to Australia. Meanwhile, the feral cats that one sees in outback Australia are as different to domesticated cats that one would consider them a different species (my mother, who used to work in rural Australia, saw examples of feral cats that looked twice as big as a domesticated cat and whose faces looked considerably different). Some of these cats can trace their ancestory in Australia back 400 or so years, leaving one to ask the question, "how long until feral cats are considered native to Australia?"

Cheers --Roisterer 06:12, 16 April 2006 (UTC)

I'm not sure that dingoes can be considered native to Australia. See introduced species for clarification; since the feral cats were introduced, by definition they cannot be native. As far as species is concerned, if these feral cats can still breed with their domestic counterparts and produce fertile offspring, they'll probably be considered the same species. Hope this helps. Isopropyl 06:32, 16 April 2006 (UTC)

You realize that you are asking a question about semantics, not natural fact? Native is an especially slippery word, but in this type of context native usually means only that things or people of its kind were already present in that place when people speaking a European language first arrived. Much evidence suggests that nearly all people and animals and plants have not existed forever in a particular place but arrived at that place at some time in the past. There is no precise answer to "how long should x have existed there before we can call it "native". alteripse 12:09, 16 April 2006 (UTC)

Eyes and sunlight[edit]

Why are eyes so heavily affected by sunlight? All it is is just a bunch of photons, it shouldn't be all that harmful.

Gamma radiation is "just a bunch of photons", too. --BluePlatypus 06:34, 16 April 2006 (UTC)
See Sun#Sun observation and eye damage. —Keenan Pepper 07:45, 16 April 2006 (UTC)
The problem is the photons are at too high of an intensity in number that the eye is built to handle... not that the eye was built. -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 11:29, 16 April 2006 (UTC)

A photon is pure energy. The eye is a delicate instrument that aquires, measures, and organizes information on that pure energy. If that pure energy is too much energy, then it damages the sensitive parts of that delicate instrumnet. WAS 4.250 17:38, 16 April 2006 (UTC)

Its just like cooking something....as long as the flame is under control the food gets cooked properly....but if you increase the flame or the heat given to it, it gets over cooked and in extreme cases, burnt... our eye is like the food....we dont want it to get burnt..... Jayant,17 Years, Indiacontribs 17:51, 16 April 2006 (UTC)
As our article says our eyes have evolved to stand directly looking at the sun by accident with little chance of permanent damage. Light concentrating optics and partial solar eclipses are where the real danger lies. The former can hardly be called part of our natural environment and the later is a pretty rare event. Plugwash 17:59, 16 April 2006 (UTC)

The human brain is also probably part of the reason. Just like pain receptors reacting though no damage is being done, the brain has probably evolved to make it seem that our eyes are very sensitive to the sun, in order to teach our less intelligent ancestors a lesson before they started making hobbies of looking at bright yellow balls.  freshgavinΓΛĿЌ  05:12, 17 April 2006 (UTC)

Photons are massless particles, therefore may be said as pure energy. Too much energy in the eyes- ouch! Luthinya 10:37, 17 April 2006 (UTC)

Squiggly shapes in the eyes[edit]

In certain lighting conditions I can discern small transparent shapes in my eyes. i guess they are suspended in the sclera, as any attempt to look directly at them results in them moving away in relation to the movement of the eye (a rather comical situation). The shapes are varied, but range from small spots to squiggly-amoeboid shapes, all very small.

Other people seem to have them as well. I looked but couldn't find what I was looking for under disorders of the eye.

What are they, are they bad, and is there any way to remove them? Cheers, Wapatista 09:01, 16 April 2006 (UTC)

See Floater. — Knowledge Seeker 09:08, 16 April 2006 (UTC)
They are normal, don't worry about it. Also see Phosphene -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 11:28, 16 April 2006 (UTC)
I've been seeing them for more than 10 years now... if they are really bugging you, try not to concentrate on them and look at some dark area... Jayant,17 Years, Indiacontribs 14:36, 16 April 2006 (UTC)

Also, if you wear contact lenses, they may just need cleaning or replacing. Little spots on them can behave the same way. StuRat 21:56, 17 April 2006 (UTC)

Then again, if you don't wear contacts, try removing your corneas and giving them a good cleaning, LOL. StuRat 00:35, 22 April 2006 (UTC)

Center of Mass & Center of Gravity[edit]

I have a conceptual question about a roll of toilet tissue. Are its center of mass and center of gravity the same? Also, could they located in the hollow inside of the roll?Patchouli 14:16, 16 April 2006 (UTC)

Assuming that the roll is in a uniform gravitational field, the center of mass equals the center of gravity, and they are at the center of the roll, in the hollow inside of it. --Andreas Rejbrand 14:22, 16 April 2006 (UTC)
Wow, that center of gravity article is a travesty. We've gotta fix that. Melchoir 06:22, 17 April 2006 (UTC)

Evolution-based explanation for physical differences among races[edit]

Native inhabitants of difference parts of the world have different physical features. For example, Europeans tend to have lighter skin/eye/hair colors and "pointier" nose shapes etc. Africans, on the other hand, tend to have darker skin/eye/hair colors, bigger and rounder noses, and hair with very small curls. From the standpoint of evolution, these differences should be explainable in terms of adaptations to the environment and evolutionary advantages. I've tried to come up with an evolution-based explanation for the differences in nose shapes and hair texture, but I couldn't tie these differences to evolutionary advantages. Is there a consensus among scientists as to how nose shapes and hair texture affect survival in different geographic regions?

There is a process called genetic drift by which traits can become common in a population by "chance" without there being a "reason". You can speculate about "reasons" for traits that might lead to active selection, but it is often hard to know if you have found the real cause of a trait being selected in a population. --JWSchmidt 17:09, 16 April 2006 (UTC)

There is no consensus. There are a lot of "just-so" stories ;some are nonsense; some are probably true. Current genetic studies are being done that are beginning to provide scientific evidence that address these issues. We are a long way from having it all figured out. WAS 4.250 17:46, 16 April 2006 (UTC)

Sunlight is used by the skin to synthesize vitamin D. However, too much sunlight causes skin damage. So, in the tropics, where sunlight is abundant, melanin is needed in the skin to absorb most of the sunlight, while in temperate zones, light skin is needed to let the lower quantity of light in. Large nostrils are helpful for breathing, especially when hot. However, large nostrils in cold areas would allow too much cold air in and damage air passages. Straight hair is better at retaining heat and curly hair is better at cooling. StuRat 23:23, 17 April 2006 (UTC)
Soft fatty waist-lines are ideal for balancing opened cans of beer in a sitting position.  freshgavinΓΛĿЌ  07:00, 18 April 2006 (UTC)

EMF (or WMF) to SVG converter[edit]

Does anyone know any free software able to convert EMF (or WMF) images to SVG files? --Andreas Rejbrand 14:17, 16 April 2006 (UTC)

You mean, apart from the programs listed by typing "wmf to svg converter" into Google? --Heron 16:32, 16 April 2006 (UTC)
Well, I thought most of them weren't free (it isn't the first time I'm looking for a free converter app.), but I'll have a more carefull look at them. --Andreas Rejbrand 17:01, 16 April 2006 (UTC)

JPEG thumbnail[edit]

After installing some software, my computer (Windows ME) no longer shows a thumbnails for jpegs in Explorer. Is there a registry class I should edit to bring it back again.--Bjwebb (talk) 14:37, 16 April 2006 (UTC)

That happens when the ShellEx settings go wonky. Admittedly my WinME install, in Virtual PC is very old, but if you put the following into a .reg file it should, hopefully, do the trick. I take no responsibility if this causes the heat death of the universe. --Blowdart 08:23, 18 April 2006 (UTC)

Do you mean .reg? --WhiteDragon 19:00, 20 April 2006 (UTC)
Err yes :)N --Blowdart 03:21, 22 April 2006 (UTC)
REGEDIT4

[HKEY_CLASSES_ROOT\.jpg\ShellEx]

[HKEY_CLASSES_ROOT\.jpg\ShellEx\{BB2E617C-0920-11d1-9A0B-00C04FC2D6C1}]
@="{7376D660-C583-11d0-A3A5-00C04FD706EC}"

Rapyrox[edit]

In a book I was reading, a old lady held an injection of 'rapyrox' against some guy's leg and held him hostage that way. What is rapyrox? I've done google searches, and I get nothing. Recon0. (talk) 14:47, 16 April 2006 (UTC)

I have tried to search for 'rapyrox' using several search engines but havn't found anything. Hence, it is most likely that the word has no real meaning, but is only a "invention" of the author. --Andreas Rejbrand 14:52, 16 April 2006 (UTC)
I made an article on what it means here --Elixer202 05:00, 2 July 2006 (UTC)

An Unusual Error in Matlab Program.[edit]

Hi, i was trying to create a program to find out the sum of the digits of a given number until the sum was a single digit. For example, if i find sum of digits of the number "15", then it would be 1+5=6. But for "47", it should be 4+7=11 and 1+1=2. so i just wanted to write such a program. First i tried in C, but there handling of floating point variables would have posed problems, so i tried in Matlab. The following is the code which i wrote in Matlab. Please note that in the following code, "type" is the variable whose sum of digits i want to find out. And the variable "sumfinal" stores the final value of sum of digits.

THERE IS A PROBLEM WITH WIKIPEDIA'S CODE DISPLAYING METHODS, I HAVE MODIFIED THIS CODE ON THIS PAGE SO THAT IT SEEMS EXACTLY AS IT IS, BUT WIKIPEDIA ITSELF CREATES NEW INDENTS AND MAKES IT QUITE CLUMSY.

%%%%%%%%%%%%%%BEGINNING OF CODE%%%%%%%%%%%%%%%%
clear
format long
sum=0;
temp=0;
num=2222222222222222222;  % this is the number
while temp==0
    while num~=0        
        digit=mod(num,10);
        sum=sum+digit;
        num=(num-digit)/10;
        sum
    end
    
    
    if sum>9
        num=sum;
        sum=0;
        
    else
        break
    end
    
    
end

sumfinal=sum;
sumfinal
%%%%%%%%%%%%%%%%%%%% END OF CODE %%%%%%%%%%%%%%%%%%%%%

Now, the problem is that i tried out various combinations of numbers and all of them worked out well, but suddenly i found out that whenever i was entering numbers in multiples of "19", the results were not correct. For example, when i entered "1" nineteen times, the correct result displayed by "sumfinal" should be "1", but it shows "9". So i tried it with "2" nineteen times, even then the result was "9", though the correct result should be "2". And surprisingly for "3" nineteen times the result was "-456". So could anyone please help me with this problem. And could you also provide with the bug-free code for this problem of summation of digits. PS: I have been programming in matlab since last 8 months or so, so i am quite experienced in that. secondly, if anyone says that "2" repeated nineteen times is large number , and will not be handled correctly by matlab, then its incorrect to say so, because for simple calculations also, extremely large numbers beyond imagination can be handled. So the "range" is not a problem. I use Matlab 7.

To show code in html enclose it within <pre>...</pre> elements. Can't help you with matlab, but here's some C code that i think does what you want.
void add_digit(char* a,int c) {

  if(!*a) *a = '0';

  c += *a - '0';
  *a = '0' + c % 10;

  c = (c - (c%10))/10;
  if(c>0) add_digit(++a,c);
}

void sum_digits(char* a) {

  char* sum = a++;
  while(*a) {
    int c = *a - '0';
    *a++ = '\0';
    add_digit(sum,c);
  }
}

int main() {
  char num[256] = "2222222222222222222";
  do {
    sum_digits(num);
    printf("sum digits: %s\n",num);
  }while(num[1]);
  return 0;
}
This works, as long as you don't mind reading the interim sums right to left.EricR 17:23, 16 April 2006 (UTC)
Good evening! I happen to believe that the sum of the digits of any number (base 10) is mod(num,9) where mod is the modulo function. If you have it, use it. --DLL 18:49, 16 April 2006 (UTC)
It took me forever to see why the mod 9 method didn't look right to me. It requires an extra check. If it returns 0 and the initial number was not 0, you need to change it to 9. Otherwise, the mod 9 should be correct. --Kainaw (talk) 18:59, 19 April 2006 (UTC)
A simple one-line solution would be: "while(number > 9) { number = (number % 10) + (number / 10) }" This assume integer division on "number / 10". If you don't have that, use "floor(number/10)". In the end, "number" will be the one-digit sum. I didn't check this with a lot of numbers, but it worked for a handfull of them. --Kainaw (talk) 19:11, 16 April 2006 (UTC)
Well, if you've got arbitrary sized integers that works great. Try a few > 2^32 or 2^64. EricR 20:12, 16 April 2006 (UTC)
culd store them in a string as well and split it up etc --24.193.235.188 07:04, 17 April 2006 (UTC)

Face-to-face intercourse in animals[edit]

What animals, if any, engage in sexual intercourse face-to-face other than humans? (Subquestion: Does it even make sense to consider non-mammals?) Off the top of my head, it seems like most mammals go with a rear mounting, 'doggy style' if you will. Seems like whales and dolphins would have to go face-to-face, or belly-to-belly as it were. Seems like the other primates might be the only other animals capable of face-to-face intercourse, but I think they don't. Any information out there? --Ananda

  • Bonobos face each other when copulating and are rather famous for it. --Fastfission 17:08, 16 April 2006 (UTC)
  • From Missionary position, there's also armadillos. I could swear there was also an insect that uses the position; I thought it was aphids but Google isn't helping me there. Melchoir 04:31, 17 April 2006 (UTC)
Worms don't have faces, but they screw belly up front.  freshgavinΓΛĿЌ  06:56, 18 April 2006 (UTC)
You may be interested in Non-human_animal_sexuality and Canidae#Canine_copulation. Black Carrot 02:56, 19 April 2006 (UTC)
I don't have a reference, but I believe that somebody did a study on the origins of the spread of genital diseases to the mouth to figure out when the switchover occurred for humans. Rich0 12:41, 23 April 2006 (UTC)

SSL CRT[edit]

What is the difference between a CRT that I generate using Cpanel and one that I can buy from Verisign (and others) and later insert into Cpanel? — Ilyanep (Talk) 16:45, 16 April 2006 (UTC)

A certificate Cpanel generates is a self-signed certificate, which means a client program connecting to a server using such a certificate has absolutely no assurance the server is not an impostor (sure, I'm amazon.com, trust me, I say so myself, now, what was your credit card number?). Verisign is one of a number of certificate authorities that issue X.509 certificates. To get a certificate authority to issue a certificate you have to prove you're the owner of the IP address the server will run on, so if you trust the CA you can trust that you're not talking to an impostor - for more on this please see the articles on X.509 certificates and certificate authorities. -- Rick Block (talk) 22:56, 16 April 2006 (UTC)

Simple Javascript question[edit]

I'm trying to do some simple Javascript and I seem to have forgotten how to do use the DOM correctly. All I want is a function which will cycle through all of the checkbox elements with an id of "record" and set their "checked" property to "true". What's the best way to cycle through them all? I'm frustrated and not finding easy answers Googling around. --Fastfission 16:54, 16 April 2006 (UTC)

Could you just traverse the DOM tree?
function topDownTraverse(n) {

  // do something w/ the node

  for(var m = n.firstChild; m != null; m = m.nextSibling) {
    topDownTraverse(m);
  }
}
EricR 22:16, 16 April 2006 (UTC)
I'm not sure what you're referring to with the traversing, but I know that checkbox elements have a property called "checked", which it shouldn't be too difficult to set to true. You can use the "forms" array builtin to the DOM to cycle through the forms, and if there is more than one element "record", it will be an array and a property of forms[]. Try something like:
function checkallrecord() {
        i = 0;
        j = 0;
        while (document.forms[i]) {
                while (document.forms[i].record[j]) {
                        document.forms[i].record[j].checked = true;
                        j++;
                }
                i++;
        }
}
Note that this won't work with only 1 checkbox called "record". For anything more than 1, it should be fine. It also doesn't work if the checkboxes aren't encased in 1 or more <form> tags. Hope this helps. -- Daverocks (talk) 11:38, 17 April 2006 (UTC)
A tree traversal algorithm can be used to visit each node of a tree (data structure). The DOM represents parsed documents as trees. During the traversal it's easy to check the node type, name and id, then set any properties you like. EricR 17:25, 17 April 2006 (UTC)

Solar Power[edit]

I'm wondering if anybody out there is very experienced with solar power.

I'm not very familiar with the terms involved with electricity and magnetism, so please bear with with me.

Approximately how large would a solar panel have to be, given the approximate average amount of sunlight available in North America, to keep a recharchable battery powerful enough to power a five watt light bulb, sufficiently charged to constantly have power available to turn the light on whenever needed?

If my question is confusing, if I'm using the term "watt" incorrectly or if I'm leaving out some other variable I'll gladly clarify it to the best of my ability. Thanks to anyone who can help me with this. Loomis51 17:06, 16 April 2006 (UTC)

Your question is perfectly alright...:-D ....and from the solar cell article:
When exposed to direct sunlight, a 6-centimeter diameter silicon cell can produce a current of about 0.5 ampere at 0.5 volt (equivalent to about 90 W/m² average, range is usually between 50-150 W/m², depending on sun brightness and solar cell efficiency).
So..i'd guess that'd give you a good idea of how big the panel has to be... Jayant,17 Years, Indiacontribs 17:45, 16 April 2006 (UTC)

Thanks for the link, but as I said, my knowledge of electricity and magnetism is very poor, so I can't really make sense of all the terminology. Could you tell me how all of that translates into the actual size necessary for the panel? And if I can ask a further question, would you have a rough estimate of what the cost of the panel and the battery would be? (Nevermind the bulb) Thanks! Loomis51 18:13, 16 April 2006 (UTC)

You are welcome... The terminology (90W/m^2) means that for every square meter of a silicon solar cell it produces about 90 W.... so..if you want to recharge a 5 watt bulb..... the area should be 0.055 square meters..... so the area should be around 60-100 square centimeters.... and as for the cost, i dont know about the price in North America since i dont live there...i'll try to search for the price on the internet and put it over here... Jayant,17 Years, Indiacontribs 21:09, 16 April 2006 (UTC)
Yeah...here we go... that site gives a lot of information on solar panels...and gives you some models for sale..... hope you find them useful...try calling up some of the phone numbers on the website and talk to them...... if you want more information, just ask...:-D ..Jayant,17 Years, Indiacontribs 21:18, 16 April 2006 (UTC)

Thanks Jayant, you've been a great help! If only all Wikipedians were as courteous and helpful as you. I'm sure I'll have a few more questions in the near future, but for now I'll check out the sites you mentioned. Thanks again! Loomis51 00:22, 17 April 2006 (UTC)


This is a very easy question. All you have to do is think in terms of ENERGY. A 5 watt light bulb comsumes 5 joules of energy per second. Assume that you need the bulb to be on 24 hours per day. 1 day = 24 * 60 * 60 seconds or 86400 seconds.

Therefore a 5 watt bulb requires 5 * 86400 or 432000 joules per day. So all you need to do is to calculate the (area) amount of solar panels to generate as least 432000 joules of electrical energy per day.

Solar panels tells you how much power (in watts) they generate in the "best case senario" so you need to account for the "worse case senario". Also remember that there is no sun light at night. So multiple the "watts" of the solar panel by the amount of sunlight in seconds and make sure you includes some redundancy for cloudy periods to get the amount of energy stored per day.Ohanian 04:43, 17 April 2006 (UTC)

Well, you cannot really charge up a light. What you can do is charge up a battery which can run the light. A standard rechargable battery (type D, C, AA or AAA) can be charged up using three of the above solar cells in series to deliver 1.5 volts. Make sure you leave it in strong sunlight, and only use a light bulb intended for 1.5 volts. You might also want to put a rectifier in the circuit to make sure it does not discharge itself when it is dark. One other problem is the battery will tend to lose its ability to discharge if left charged up for a long time. Have you heard about the Faraday Flashlight?

I have got one for emergencies, not a bad deal.

Which Test To Find P-value And How Many Freedom Degrees?[edit]

I've done an experiment where we took ONE SAMPLE of neurones, extracted something from them, split it into two samples and measured the quantity of a chemical in the solution, comparing it to a control set of neurones which were treated more nicely during incubation. Do I have one or zero degrees freedom? Although a repeat was performed, it was using the same sample extracted from one set of neurones? How do I know which is the appropriate statistical test to find a p-value? -Username132 (talk) 17:54, 16 April 2006 (UTC)

It sounds like there is one degree of freedom, whether it was treated "nicely", or not, as you put it. StuRat 23:03, 17 April 2006 (UTC)
What I meant was that there were some control neurones which were incubated with nothing special added to them, and some others (the mistreated ones) where we added NMDA. Here's how the experiment went down;
One control sample > split into two > chemical measured > average taken

One NMDA sample  > split into two > chemical measured > average taken
The two averages were then compared. Since we only took one sample of neurones for each the control and NMDA treated neurones (i.e. one rat) and split the sample into two, I think because there was only one rat involved (out of the entire global population), there are zero degress of freedom. You understand what I'm saying?
Either way though, what is the test used to compare to values in this way? --Username132 (talk) 00:31, 18 April 2006 (UTC)
I don't believe any statistical significance test can function with a sample size of 2 (assuming "split into two" means they're meant to function as seperate samples). It seems like they generally need at least a dozen. Without that, there's no way to guess at how wide the standard deviation is. If I understand degrees of freedom right (a big if), I think you have one. I think there are two variables being measured (one categorical and one numerical), and that only the dependent variable (the numerical one) is counted as a degree of freedom. If you get a bigger sample size, the t-test is what you want. Whether it should be paired-sample or not is a bit trickier. All the samples come from one rat, which means they're related, but within that rat the neurons are (I assume) randomly chosen. You'd use an independent sample test (testing the relationship between two well-distributed, unconnected sets of samples) and then, to take into account the effects of the single rat, state in your conclusion that your results only apply to the rat tested and can not necessarily be extended to the general population of rats. If you don't want to go back and get a larger sample, you could of course fake your results (not recommended), use the test anyway (equivalent to faking results, but without as much of a stigma attached), or just subtract one average from the other and mention in your conclusion that the results may or may not be representative. Black Carrot 02:27, 19 April 2006 (UTC)
One further thought: I'm not actually at all sure you did choose the neurons randomly. You certainly wouldn't have gotten a randomly distributed sample from throughout the brain; I'd expect you to just cut out a small section that looks similar to the rest. That means that the results would apply only to whatever particular types of cells made it into the sample. Also, there's an important difference between simply cutting that sample into pieces and mixing it up, then seperating it into equal amounts. The second would be random (but might damage the cells), and the first would not. Unless you can ensure that the cells in the sample are identical (well, that the inevitable differences between them are negligible), which would be difficult, no statistical test can be really reliably performed. Black Carrot 16:07, 19 April 2006 (UTC)
Thanks! The neurone sampling was done by the technicians (I actually recon there are no neurones involved and they just did it with chemicals - a lot more predictable, cheaper and more suitable for a university experiment). If the results are insufficient to perform a statistical test, I'll just include this in my critical assesment of the experiment which is a lot easier for me!
When you mentioned result fudging (my result-fudging days are over I hope!) did you mean to infer that it goes on in the real world by actual research groups? If so, how frequently does this occur? And what are the motivations, aside from having an investment in the company selling a certain product?
The biggest fudge I ever did was to draw the graph I wanted, plot points around the line, take those points as my averages and make up three repeats that gave that mean average!! Those were the days... -Username132 (talk) 08:09, 23 April 2006 (UTC)

Chronology / Inability to locate events in time or to remember dates[edit]

I stumbled across an interesting phenomenon: While I was trying to locate a painting to a particular epoch, I asked a friend. This friend told me that she cannot remember dates and does not have the ability to juxtapose events in for example political history with events in art history. In other words, a poem written in 1917 in England would not remind her of WWI and a possible connection, although she has had several curriculi in which WWI was a topic. She coined it - amusingly - date dyslexia. Now I am asking myself if there is an official expression for this "condition". Please do not propose laziness. Thank you! Don420 19:10, 16 April 2006 (UTC)

I don't know, I am inclined to think laziness, or at least an inattentiveness to context. ;-) --Fastfission 21:35, 16 April 2006 (UTC)
I'm a little confused. Would she be able to recognize a painting as one of WWI, from the style and content (no dates involved)?  freshgavinΓΛĿЌ  05:02, 17 April 2006 (UTC)
Good point. Your question with regard to WWI may be a difficult one since the telltale signs will be predominantly technical - trenches, weapons, radios, gas-masks, tanks, etc. These are elements generally not of interest to her. During my initial surprise at the phenomenon, I asked "when did Picasso live and when was his influential work done?" - having had art history during her education as a photographer and graphic designer - she was not able to say. For the exams she took, she had to learn the dates by heart. At the moment she is working on a Jugendstil design, taking inspiration and researching in numerous books. When asked about the time Jugendstil was active, she could not say except early 20th century. Louis XIV, Biedermeier or Manerism - no clue as to the dates, but she may be able to recognize the styles without the ability to place them in a chronology. Don420 09:58, 17 April 2006 (UTC)
Then it sounds like she just has a serious problem remembering dates, which seems plausible enough. I still don't understand why she didn't get the poem was about WWI, if it included WWI details. The date 1917 doesn't really seem to relate. If you read me a poem written in 1917, I wouldn't be able to tell you when it was written either!  freshgavinΓΛĿЌ  06:54, 18 April 2006 (UTC)
It is probably just this simple, then... Thank you both for your time and help! Don420 09:13, 18 April 2006 (UTC)

One Line C Program Signatures[edit]

Hey There

I've seen around a lot some seriously funky 1 line C/C++ programs that are commonly found in signatures that when compiled produce a really nice pattern or shape, such as:

main(c,r){for(r=32;r;) printf(++c>31?c=!r--,"\n":c<r?" ":~c&r?" `":" #");}

Is there a name for these, and if so, does Wikipedia have an article on them, or does anyone know of a place that lists them? I'd really like to know as i find them extremely interesting and astonishing how one loop can produce such amazing results. Thanks :) -Benbread 21:46, 16 April 2006 (UTC)

Yes. That's mainly due to the language. In this particular case the ?: operator plays a vital role as it allows a single expression to replace a set of much verboser if-else. Also, implicit comparison with zero and operators precedence play a (minor) role. Just to give you an idea, a spelled out version of the program could be:
#include <stdio.h>
int main(){


    int c = 0;
    int r = 32;

    while (r != 0) {

        c = c + 1;
        if (c > 31) {
            c = !r;   /* same as c = 0 */
            r = r - 1;
            printf("\n");
        }
        else {
            if (c < r) {
                printf(" ");
            }
            else {
                if ((~c & r) != 0) {
                    printf(" `");
                }
                else {
                    printf(" #");
                }
            }
        }

    }
}

--Gennaro Prota 13:03, 17 April 2006 (UTC)
These are called signature programs, and there is no Wikipedia article on them (yet). One place with a list is http://www.iwriteiam.nl/SigProg.html. -- Rick Block (talk) 22:36, 16 April 2006 (UTC)
What a headbangingly obvious name. Thanks very much - I think i'll start working on that wikipedia article tomorrow (well, today, after i go to bed) -Benbread 23:13, 16 April 2006 (UTC)


Please, keep in mind however that most of these are pre-standard programs, more than often relying on the particular and possibly undocumented behavior of a particular compiler (usually gcc at the time of writing the program). In the best of the hypotheses they lack the necessary includes, but usually it's worse than that. The example above, besides lacking #include <stdio.h>, doesn't specify the return type in the declaration of main, has an absolutely non-standard "main(c,r)" incipit and other subtleties. And it would require a quite careful analysis to see if it doesn't invoke undefined behavior (note in particular the increment of c without initialization).
P.S.: I was almost forgetting... if you write an article on this, please, never write "C/C++". That expression makes many C and C++ programmers literally fly off the handle :)
--Gennaro Prota 12:40, 17 April 2006 (UTC)


I was just wondering...can you tell me what the output of the program would be.. I know a bit of C/C++ but i dont have the language on my computer to try it out..Thanks a lot. Jayant,17 Years, Indiacontribs 09:05, 17 April 2006 (UTC)
This is what the output of the above program looks like. -- Daverocks (talk) 11:51, 17 April 2006 (UTC)
Tech savvy teenagers! What would Wikipedia be without you? :-) See, it's this sort of stuff that makes it interesting to come back to the reference desk over and over and over! --HappyCamper 17:42, 17 April 2006 (UTC)
Thanks a lot for that!! and its a pretty cool program..i must admit...;-D ..Jayant,17 Years, Indiacontribs 19:06, 17 April 2006 (UTC)
BTW, it could be easily generalized. And a couple of changes would make it strictly portable (such as replacing ~c&r with (31-c)&r or in general (h-1-c)&r; note that I declared c as int and left ~c in my code: it was meant to be a faithful "rewording" of the original, not a fix). In any case I guess the intent was for r to start from 31; when it starts from 32 it will just produce an additional "all-space row" at the beginning.
P.S. for HappyCamper: if you liked this you might enjoy googling for "IOCCC" :)
Cheers. --Gennaro Prota 21:17, 17 April 2006 (UTC)
Excellent answers thanks - About the whole C/C++ thing, sorry about that, in my spare time i do write a little C++, but wasn't aware it annoyed many people to see the usage of the above, but I can see why. Thanks again, everyone, particually Gennaro Prota :) -Benbread 23:50, 17 April 2006 (UTC)
You are welcome :) About "C/C++" no need to apologise, I was just pointing out the mainstream attitude, so to speak, which you can read about at http://www.faqs.org/faqs/C-faq/learn/, under "What is C/C++?". In any case the best answer is that by Rick Block, I just went off at a tangent :) We could clean this up a bit for the archive. I was thinking to insert a brief introduction to Sierpinski triangles (or references, preferably internal to Wikipedia) and explain how the expression ~c&r originates, from a mathematical point of view. --Gennaro Prota 11:41, 18 April 2006 (UTC)


I've created the starting point of a Signature program article. Many thanks to everyone whos information has helped to make it. I've linked to this question in the talk page to show credit where it's due, as well as thanking some members personally. If you oppose to me rewriting some of your information (but it's public domain anyway) feel free to remove my information and repost it as your own. Thanks again for helping me and making wikipedia a better place :) -Benbread 16:41, 18 April 2006 (UTC)
I had a quick look. The overall style and prose is very good to me. Some details are wrong (for instance, such programs are rarely "optimized"; the example above for instance, outputs all the leading space of a line one after another, even if a single string of appropriate lenght could be printf'd in one shot); they are just "terse" (you could say they optimize (minimize) the number of keystrokes :)). But don't worry, I'll fix it in the next days. What matters is the overall structure which is IMHO very good. As to the example program I don't know if it is copyrighted or not and considered that it has some errors (such as not printing the last line of the triangle) I think I'll replace it with a correct version. If one doesn't care having a spurious space after the '#' that terminates each line it could be quickly fixed as here:
/* Pass a power of 4 as argument for h */
void print_it (unsigned h)
{
    const unsigned n=-1;
    unsigned c = n;
    signed   r = h-1;

    while (r>=0) printf(++c>=h?c=n,--r,"\n":c<r?" ":~c&r?"` ":"# ");
}


but of course it can still be improved. I'll try writing a version of my own without looking at external sources, so that we can't have copyright problems. Ah, I also moved the article, to conform to our usual naming convention ("Signature program", with a lowercase 'p'). And thanks to *you* for your good job :) --Gennaro Prota 18:22, 18 April 2006 (UTC)

Microsoft Excel[edit]

Is there a way so that I can write something in a cell without it continuing into next cell. It just stays in the cell you are typing in.

I don't have a copy of Excel available to me right now as I'm on a Linux system, but you should be able to choose Cell properties->Text format (or text alignment?)->wrap text, or something very similar, and any text which is too long for the cell will display over multiple lines. If the row height is standard, then you won't be able to see these lines, but you can adjust the row height should you wish. In OpenOffice.org, it's Format cells->alignment->Wrap text automatically, and you also have to choose Format cells->alignment->Vertical->top to get exactly the same result.
An alternative way of stopping long text in one cell from extending over the next (blank) one is to put a space in the next cell.
Is this what you wanted, or am I misunderstanding the question?-gadfium 23:20, 16 April 2006 (UTC)
It's under 'format cells', 'alignment' to wrap text. The other suggestion, putting invisible content in subsequent cells, will also work but is not recommended (most notably because excel deems any edited cell to be part of the: print area, edited area (for when you use the home/end keys to navigate, etc) and also for formula-related issues.--Anchoress 05:11, 17 April 2006 (UTC)
Thanks, I learned something too!-gadfium 05:30, 17 April 2006 (UTC)
No problem! If you ever have a short Excel spreadsheet that outputs pages of blank cells on printing, you may infer that at some point cells elsewhere in the sheet have been edited. Using the keystroke, 'CTRL+END' will take you to the bottom-right-most edited cell, which will give you an idea of where the extra edits might have occurred.--Anchoress 06:34, 17 April 2006 (UTC)

April 17[edit]

Crucial Gizmo Overdrive[edit]

Does anyone know if a Crucial Gizmo Overdrive USB key will fit into the front USB port on a Dell 'monoblock'-type desktop? Cynical 15:35, 24 April 2006 (UTC)

Ramjet Project[edit]

I have been for three days attempting to build and test a stationary ramjet with no luck, I have read the ramjet article twice but I am still confused on the construction of the ramjet. So I was wondering if anyone could point me in the right direction or give me a link that explains the construction of a ramjet? I am looking for things like types of fuel ignition methods and just bassically anything on ramjets. Thank You. Patrick Kreidt

For one thing, I thought "stationary ramjet" was an oxymoron. The design requires it to be moving very fast through some medium. —Keenan Pepper 00:43, 17 April 2006 (UTC)
I agree with Keenan Pepper. A ramjet is probably not what you want. The external links on pulse jet engines might be useful to you.-gadfium 01:52, 17 April 2006 (UTC)

Well it can be stationary if you have a constant airflow, but that isnt my problem.

Not to be useless, but I'd imagine it would be pretty difficult to find any specific instructions for building a ramjet, simply because it's not the kind of thing people build from kits and most of the plans would be either highly top-secret or simply confidential.  freshgavinΓΛĿЌ  04:54, 17 April 2006 (UTC)
Ramjet engines are not that hard to build and not top secret. Keenan is right in that it needs a flow of air to work. All you need for a stationary one is a large pipe with a one way valve at one end. Have some sort of pump to deliver a find mist of fuel inside, a fan to keep air pressure flowing through the valve and a sparker (like a spark plug) to ignite it. Don't blow yourself up.
I could be wrong, but I wasn't aware that companies like Boeing, NASA, etc., reveal the entire technicalities of their prototype designs.  freshgavinΓΛĿЌ  06:50, 18 April 2006 (UTC)

Thanks

Can a substance conduct heat well but not eletricity (and vice versa)[edit]

Title says it all, but if it is true could you explain how. It's not hw and any help would be apprecaited.

I believe epoxy was designed for just that. I just can't remember whether it's excellent at conducting heat but not electricity or the other way around. Loomis51 01:24, 17 April 2006 (UTC)

A material is electrically conductive if it contains charged particles that are free to move around, like electrons in a metal or ions in a salt solution. A material is thermally conductive if mechanical vibrations (heat) are quickly transferred. Diamond and deionized water are both thermal conductors but electrical insulators, because their particles are strongly attracted to each other and spread vibrations quickly, but there are no mobile charged particles to conduct electricity. I can't think of a good electrical conductor that is also a thermal insulator, but I can't say for sure there aren't any. It might be because the charged carriers also conduct heat... —Keenan Pepper 01:29, 17 April 2006 (UTC)

Thanks.

Possible. One of the best examples would be the mica used as electrical insulator but thermal conductor in the electric irons - Wikicheng 06:11, 17 April 2006 (UTC)

Good thermal conductivity without electrical conductivity is somewhat unusual. Try http://en.wikipedia.org/wiki/Beryllium, it talks about Berylium Oxide as having this property, but the Berylium Oxide article leaves it out.

Diamond is the prototypical example of a good thermal conductor (possibly the best thermal conductor known) but a bad electrical conductor, i.e. an insulator. Heat in materials is transferred in two ways, either by electrons or phonons. Phonons are essentially vibrations of the crystalline lattice, and heat in diamonds is transferred purely by phonons. But, because electrons conduct both heat and electricity, it is impossible for a material to conduct electricity and not heat. If it is electrically conductive, electrons must exist and be mobile within the material, and would therefore be capable of transferring heat.

Physics Problem[edit]

You place a 7.50 kg television set on a spring scale. if the scale read 78.4 N, what ist he acceleration of gravity at that location? Seems easy enough, I get an answer butr that isn't what the answer key "says". I went F = ma, F/m = a.... a = 10.45m/s/s.

The answer I'm given is 9.973m/s/s, and I have no idea how that's derived. Anyone know if I missed something or if I'm right? Thanks.

00:58, 17 April 2006 (UTC)

Perhaps a dyslexic teacher? As far as I can tell if the answer is 9.973 the scale should say 74.8N. -- Rick Block (talk) 01:22, 17 April 2006 (UTC)
Haha very nice. I have another question where I inexplicably get 312 instead of 321.....I'll assume it's right. Thanks.

01:30, 17 April 2006 (UTC)

Your answer is correct for the given problem. If m = 7.50 kg and F = 78.4 N the acceleration due to gravity is a = F / m = 10.45 ms^(-2) Cedars 10:22, 17 April 2006 (UTC)

I think that you must make the below experiment in order to define the acceleration of gravity.

Get one string with the length is about 4m, tie one end of the string at a ceiling, another is free and tie one ion piece with the weight is about 100gram,you have a pendulum ,you can mesure the cycle of the pendulum (it is T),(the angle of pendulum swing is about 10 degree)You can mesure the lenght of string from a ceiling to ion piece, it is l, T = 1/2pi*l/g , you can extract g . I think Rick Block is right . Ngocthuan 06 01:36, 24 April 2006 (UTC)

Electromagnetic spectrum upside down?[edit]

Usually on a vertical scale the smallest number is on the bottom and the largest number is on the top or if the scale is horizontal the smallest number is on the left and the largest is on the right. The electromagnetic spectrum is always shown with the longest wavelengths (long electric waves, radio waves) on the bottom/left and the shortest wavelengths (X-rays, Gamma rays) on the top/right. I am wondering what is the scientific reason for doing this. Llarsson 01:20, 17 April 2006 (UTC)

I think it's probably due to increasing frequency (and therefore, energy) as you go up the scale. — Knowledge Seeker 01:24, 17 April 2006 (UTC)
It really doesn't matter. Frequency goes down as wavelength goes up, so either way you put it, one of the scales would go the "wrong" way. —Keenan Pepper 01:31, 17 April 2006 (UTC)

I understand that as wavelength increases, frequency decreases so one scale would go the "wrong" way. It seems to me though that since the electromagnetic spectrum shows waves and not frequency that one would lay out the scale to show wavelength increasing. Since it does not I wonder if it is more than just a 50-50 chance that it is laid out that way. Llarsson 01:50, 17 April 2006 (UTC)

As the whole spectrum is continuous, there's no real right or wrong way to view it. Luthinya 10:40, 17 April 2006 (UTC)

BitTorrent[edit]

I need help with BitTorrent.

I downloaded a file from a search and then downloaded BitTorrent and opened the file with the program. It's finished downloading and I don't know where to go now so that I can view the video.

Thanks.

When you opened the Torrent file, you told it where to download the file to. Remember where you saved it, and use that location to open the file. Simple. Here7ic 04:16, 17 April 2006 (UTC)
Never lose porno, especially not when it is on a computer that other people also use. Open your downloads window and click the button that reveals the file location that you downloaded. Assuming that you haven't cleared the list, or do not use internet explorer. -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 06:11, 17 April 2006 (UTC)

is there a name for the tendency to see patterns?[edit]

I seem to remember at some point learning a name for the principle that humans tend to see patterns in random data where there are no patterns. Constellations, inkblot tests, that sort of thing. I seem to think there is someone's name associated to it, like "someone's law" or "someone's principle". Searching on the internet for a while provided nothing, and I'm starting to think that maybe I'm imagining it. Is there such a name? -lethe talk + 03:35, 17 April 2006 (UTC)

Gestalt psychology? —Keenan Pepper 03:57, 17 April 2006 (UTC)
Ink blots are the Rorshasch test. Probably not what you seek. GangofOne 05:15, 17 April 2006 (UTC)
pareidolia --Femto 13:51, 17 April 2006 (UTC)

Also, the specific case where patterns of human behaviour are seen where none actually exist, is called anthropomorphization. That's the longest word I commonly use, BTW. StuRat 21:41, 17 April 2006 (UTC)

The question used the interesting phrase "where there are no patterns". Who says there are no patterns? Nobody has ever suggested that the Southern Cross was consciously designed to appear this way to people in the southern hemisphere of planet Earth, so it's just a random occurrence. But there's still a pattern there, because my brain says there is. To someone who can't discern the cross (and I know some people who just can't see it), there is no pattern. So is there a pattern there or not? It seems to depend on the viewer's perception. JackofOz 02:40, 18 April 2006 (UTC)

I would say the pattern is all in your mind. It's interesting how culture shapes the perception of patterns, as well. For example, the Big Dipper constellation looks like different things to different cultures. StuRat 02:00, 19 April 2006 (UTC)
All patterns are "all in the mind" of the observer, as your Big Dipper example demonstrates. All so-called reality is an illusion (albeit, as Einstein said, a very persistent one). JackofOz 02:28, 19 April 2006 (UTC)
I disagree. When looking at an actual large ladle, you really are looking at a "big dipper", not just imagining one (as when you look at collections of randomly located stars). StuRat 09:18, 20 April 2006 (UTC)
It doesn't matter what the constellation is called from culture to culture, or what individuals imagine it looks like. In the context of this question, all that matters is that humans tend to notice patterns in such things as random collection of stars. I'm not imputing anything divine or mystic in that, but to say "where there are no patterns" is to deny the experience of billions of humans over a vast period of time. And from a mathematical point of view, to suggest there are no patterns in a bunch of millions of randomly scattered stars in a particular field of view would be utterly absurd. It's a wonder humans haven't noticed far more patterns in the sky than they actually have; they're all there just waiting to be noticed. JackofOz 11:03, 21 April 2006 (UTC)
And there is a name for the tendency not to see patterns : atheism, or Darwinism. Also, written patterns are hard to decipher, so I'll add :) --DLL 19:40, 18 April 2006 (UTC)
I don't think there's a specific term for this other than pattern matching or pattern recognition. The human brain is hardwired to see patterns all over the place, it is a decent evolutionary advantage though it sometimes goes pretty haywire. --Fastfission 02:33, 20 April 2006 (UTC)
We're particularly good at seeing faces - so much so that we even once thought there may be a face on Mars. Some idiotspeople still think so. — QuantumEleven | (talk) 11:54, 20 April 2006 (UTC)

It wasn't anything like that, it was actually a pirated motion picture.

I seem to recall learning in a psychology class about a study where subjects listened to a steady beats of a certain sound. They naturally heard them as organized into groups of two or three even though the tones were in fact all at regular intervals. Can't seem to find mention of it on the internet. Will continue searching. -Wiccan Quagga 00:37, 23 April 2006 (UTC)

Temperature of innerstellar or innerplanetary space.[edit]

I'm probably missing something here, but I can't find the temperature of either spaces. Help? Here7ic 04:14, 17 April 2006 (UTC)

The space itself has no temperature, though you can measure it by placing objects into the space. Google says that the temperature of a perfectly conducting object at the distance of Earth from the sun will reach about 280K/7C, and you can expect objects at interstellar distances to experience near zero-K temperatures, though I'm not sure how near.  freshgavinΓΛĿЌ  04:45, 17 April 2006 (UTC)
Edit: Google also says that an object very far from galaxies and stars will probably reach a temperature of about 2.7K. Cold!  freshgavinΓΛĿЌ  04:46, 17 April 2006 (UTC)
The thing about temperature is that there has to be some matter for which you're measuring the temperature of. Temperature, at the molecular level, is basically the speed at which the molecules within matter move. Space, by definition, is a vacuum. It's devoid of matter. Therefore, no matter = no temperature. It's true, some will tell you that there may be fine dust particles in space, but then you'd be measuring the temperature of the dust particles, not the space itself. Others will say that the temperature of space is absolute zero, absolute zero (theoretically) being the state where the molecules within matter are absolutely motionless. But still, there must be matter to be measured. Space being a vacuum, there is no matter within which molecules are motionless, so absolute zero is not the answer either. Bottom line: difficult as it may be to explain or comprehend, space has no temperature. Loomis51 05:08, 17 April 2006 (UTC)
Have to disagree about the neccessity for the presence of matter. What you say seems plausible, but not true. Even matterless space is filled with electromagnetic radiation that has a characteristic spectrum, (Black body spectrum). This is what's left of the big bang, when things were hotter and closer together. After expansion, the temperature of space is now, as was said above, 2.7K. It is literally, "the echo of the Big Bang". The discoverers of this b.b. radiation got the Nobel prize. It shows up most prominently in the microwave frequecies. B.B. radiation is a fetish object for cosmologists, a lot can be determined cosmologically from studing it; the exact spectrum is known to be identical to a standard black body spectrum. Some recent satellites that study it are COBE and WMAP. If the space in question HAS a gas in it as well, the gas molecules will have a range of velocites in a certain distribution. It is computed that the e.m. radiation (better spoken of as photons) with a black body spectrum would hit gas molecules in just the right proportions to give them the velocity distribution that they indeed have. If you like, you can think of so-called "empty space" as a "photon gas"; this is not an eccentric concept in physics terminology, but a conventional one. The explanation of b.b. radiation started with Max Planck, and was the start of quantum theory, so it's a big deal, not a minor detail. (Of course if you happen to be near a star, then the photon stream is larger and you have a higher T, as Google says.) GangofOne 05:41, 17 April 2006 (UTC)
You're wrong. The definition of temperature is the average molecular kinetic energy of the matter within a given volume. No matter means no temperature, by definition.
Nor, for the record, has anyone pointed out the fact that space is not, in fact, a pure vacuum; space is actually a rather bad vacuum - there's all kinds of particulate matter there. (See here for the various measures of the density of space). We can produce much better vacuums on earth with relatively simple vacuum pumps. If space were a perfect vacuum, space-craft would not need heating systems (because there would be nothing to conduct heat from the aircraft into space). So, getting back to the question at hand, the 2.7 degree kelvin measurement is almost certainly a reference to the temperature of this interspacial matter. Raul654 06:08, 17 April 2006 (UTC)
(two edit conflicts) Temperature can be defined for lots of systems, including the electromagnetic field. Thermodynamics has come a long way since the ideal gas law. And in a perfect vacuum, you still radiate. Melchoir 06:17, 17 April 2006 (UTC)
No, Gang of One is right. The real definition of temperature has to do with the rate of change of entropy when you increase or decrease the internal energy; see thermodynamic temperature.
Spacecraft do not lose heat primarily by convection, but by radiation; there doesn't have to be anything touching them for them to get cold. See black body radiation. The 2.7 kelvin temperature refers to temperature of the black body background radiation of the universe, not to the interstellar medium per se. --Trovatore 06:17, 17 April 2006 (UTC)
Dang, it's a game of seconds out here! Melchoir 06:19, 17 April 2006 (UTC)
[Edit conflict, didn't read Raul's comment] You obviously know a lot more about what we're talking about than I do, so I'm sticking my foot out by saying that I find it hard to agree with you. I'm getting everything except the fact that you say the radiation left over from the big bang makes space itself 2.7K. It may be a semantic argument ... to experience or measure temperature (sense heat) requires absorption (loss) of heat in some way, and since space doesn't absorb heat or energy (as far as I know), I find it difficult to think that it could possibly have any, as you imply when you say the temperature of space is 2.7K. I'm having trouble finding the words but I feel like I'm dealing with a tree falling in the woods with nobody there to hear it.  freshgavinΓΛĿЌ  06:16, 17 April 2006 (UTC)
So I guess, in a sense, the vacuum does "absorb heat"; that is, you can add heat to the vacuum by increasing its content of photons in a distribution corresponding to the black-body law. See how much energy it takes to add those photons corresponding to a given increase in temperature, and you have a reasonable definition of the heat capacity of the vacuum. I think this is a standard notion but I'm a little out of my depth here; maybe Melchoir could explain it better. --Trovatore 06:28, 17 April 2006 (UTC)
Well... if you want to talk about the energy contributed by a new photon, that sounds like a chemical potential. (eh, I misread you) The volumetric heat capacity is pretty simple to define, though; it's just the temperature to the third power, modulo factors of c and hbar. Melchoir 06:55, 17 April 2006 (UTC)
Here is a link [38]. The temperatures of space differ greatly. Space near a star is a lot hotter than space far away from any galaxy. -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 06:15, 17 April 2006 (UTC)

Melchoir, I did specifically refer to the fact that within what we normally term "space" there are may indeed be particles. I suppose it's a matter of semantics. If you define space, as I do, as the absence of matter, then by definition, it's a vacuum. If there are stray particles, we're not strictly speaking about space anymore. Of course those particles have temperature. When I speak of "space", I speak of any area devoid of matter. In other words, Space=Vacuum, and Vacuum=no temperature. Loomis51 06:31, 17 April 2006 (UTC)

Actually, I have no problem with what you wrote. There's a bit of ambiguity about whether you're considering photons as matter, but we probably don't have to get into that. Melchoir 07:00, 17 April 2006 (UTC)

Okay, allow me to elaborate on my question to clear things up. What would the average surface temperature of the Earth be if it had no atmosphere and the sun was a white dwarf of, oh, .6 solar masses? Here7ic 06:49, 17 April 2006 (UTC)

I assume you'll also want to paint the Earth black and shut down its radioactivity? (Not that I feel like doing the work on this question, just saying.) Melchoir 07:03, 17 April 2006 (UTC)
Raul654 mentions the particles in space and says man-made vacuums are superior, which is wrong, terrestial vacuums are no where NEAR as good as space, as the link he provides even says: "Space is a nearly perfect vacuum, even better than the best ones made in labs on earth," (One complication that wasn't mentioned was that the black body spectrum refers to "thermodymanic equilibrium", the state without macroscopic changes. There are cosmic rays and stuff moving through space that are NOT in equilibrium. Just mentioning that in passing.) The link from the straightdope that MacDavis provided is excellent. And now, an experiment. A thought experiment. Let's consider a region of space that is a perfect vacuum that is in a chamber. That is, an enclosed space that is a vacuum. The walls are obviously made of matter; but the matter is AT SOME TEMPERATURE. Let's say we have a regular themometer, made of materials suitable for the temperatures we are about to measure. The bulb is painted black. The thermometer extends into the chamber, and it's readings can be recorded somehow. So, heat up the box to 2000 deg. C so that the walls of the chamber are at 2000degC. Remember, it's a perfect vacuum. (And the themometer is isulated from the sides of the chamber.) What temperature does the thermometer read? Absolute 0, -273degC, ie no temperature? As you change the T of the walls of the chamber, from the lowest to the highest, what temperature does the thermometer read? Is it plausible that it is absolute zero? --GangofOne 07:22, 17 April 2006 (UTC)
freshgavin says "...and since space doesn't absorb heat or energy (as far as I know)..." Well, let's say you shine a flashlight toward the Big Dipper. Energy came out of the flashlight, and it went somewhere. It went into space. So space absorbed it. The sun shines. The light that came off the sun isn't on the sun. It's in space now. So space "absorbed" it. So at the big bang, when the universe was as small a point as you can conceive, it was really hot, but then is expanded out, and the energy that made it hot was spread around as the size of the universe became larger, so the INTENSITY of the heat at a given spot became less, ie it cooled. It's expanded so much that the temperature of the energy that was in the big bang is now a uniform 2.7K. At least that's what the cosmologists say, anyway. It's some pretty mind streching stuff. --GangofOne 07:51, 17 April 2006 (UTC)
A true vacuum would only transmit heat, not absorb it. That is, while radiation could pass thru it, there would be nothing in it to absorb the heat. So, eventually that flashlight beam will heat some distant matter, depending on whether you believe in a collapsing universe, etc. Also note that space has a very low density of matter, so has a low, but not zero, capacity to store heat. So, you could heat up a large volume of space with very little energy. StuRat 21:20, 17 April 2006 (UTC)
Yes, though I'm not sure which side StuRat is supporting. I still don't really get you GangofOne. If you shine a light through me, or any other type of matter, I experience a slight increase in temperature, I may even be able to feel it, and much of the light is reflected but almost none of it goes through to the other side of me. There is a noticeable loss of energy as the light beam hits me. If you shine that same flashlight into vacuumed space, the beam travels through and there is no loss of energy so I don't see how you can use the word "absorbed".
Someone said that temperature had to do with "the rate of change of entropy when you increase or decrease the internal energy", but the article he linked to states simply that temperature is the relative molecular activity, which would support the fact that temperature doesn't exist in a vacuum.
I do believe what you say about constant levels of b.b. radition, but I would consider those as potential temperature, or unabsorbed energy. There's probably a more scientific way to say that : [.  freshgavinΓΛĿЌ  06:47, 18 April 2006 (UTC)
Light is energy. When the light leaves the flashlight it enters the space. That's all I mean by absorb. Just what thing has it.
The article you refer to thermodynamic temperature Says: "Strictly speaking, the temperature of a system is well-defined only if its particles (atoms, molecules, electrons, photons) are at equilibrium." Note that it is allowing the case where the "particles" are photons and only photons; "electromagnetic radiation" is the older way to express what is also called photons. Conventionally, they aren't considered "matter" (although if you did, the problem in question would define itself away, because the so-called vacuum now has "particles" in it.) Anyway, I feel I have to somehow to convey to you is that "empty space" with no light going through it is different from "empty space" with light going through it. In the later case, the space has energy that's not in the former. And if it's in the special case of "thermodynamic equilibrium" then it has a well defined number which characterises its intensity, know as its 'temperature'. What your intuitions is telling you (when you say "I would consider those as potential temperature, or unabsorbed energy.") is that without matter there, there is no temperature. What I am attempting to convey is that just the presense of photons and nothing else, has a temperature. In the thought experiment above I attempted to make it more intuitive by considering a closed evacuated cavity. It has a well defined temperature that you can measure. You can stick your hand in and sense it. A thermometer isolated from the sides reads the same temperature as a thermometer measuring the side of the cavity. The only connection of the thermometers is via the photons. (This cavity I discribe is the paradigmatic black body that's in all the textbooks.) Try me again if still obscure. GangofOne 07:27, 18 April 2006 (UTC)
Yes, you're making yourself perfectly clear. Like I said above this seems much like an argument in semantics. Even your vaccuum box thought experiment could be argued by me as containing unabsorbed energy that is absorbed by the walls and the thermometer thus bringing about a non-zero temperature. It could just as easily be argued your way. I guess that's one reason why people want to figure out if photons should be considered matter or not.  freshgavinΓΛĿЌ  05:43, 19 April 2006 (UTC)

Street Lights[edit]

Would anyone know how bright a basic street light is in lumens? Not a traffic light but one of those lights that illuminate streets