Wikipedia:Reference desk archive/Science/May 2006

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See Wikipedia:Reference desk archive/Science/May 2006 part 2 for the archives of May 21 to May 31 2006.

ice c can be a sock moma

Some hibernate; that's all I know. Melchoir 01:09, 1 May 2006 (UTC)

Although this is a very silly question for us Canadians, I actually found a quote: "Studies in Canada have shown some cows have gone 50 to 60 days with snow as the sole water source without any adverse effects." However, it quite uncomfortable to take a shower in snow. --Zeizmic 01:13, 1 May 2006 (UTC)

Cows shower? User:Zoe|(talk) 01:51, 1 May 2006 (UTC)
A cow shower is a brief or small area of precipitation that is heavier than "raining cats and dogs." For more information, see Raining animals. </official meteorologist opinion> EWS23 | (Leave me a message!) 02:23, 1 May 2006 (UTC)
It's quite a bit heavier than a baby shower. Grutness...wha? 06:41, 1 May 2006 (UTC)
Although I daresay some bridal showers might approach it in size. --Ginkgo100 19:46, 1 May 2006 (UTC)

Contents

Fullerene Formation[edit]

How are fullerene molecules formed? Is there a reaction mechanism process that creates hey!!!!!!!!!!!!!!!!! them or is it something else. I am particularly interested in buckminsterfullerene and its formation. Thankyou. Vollsa 01:05, 1 May 2006 (UTC)

I know nothing on this topic beyond fullerene purification. Isopropyl 01:48, 1 May 2006 (UTC)
Basically, you just zap graphite with lots of electricity (in a vacuum), which makes a messy mixture of all kinds of fullerenes and nanotubes. That's why the purification process is so important. —Keenan Pepper 02:09, 1 May 2006 (UTC)
You can actually make some fullerenes and nanotubes, as well as excessive amounts of graphite by building an arc furnace in your backyard. Something pretty unsafe to the common man, arc furnaces involve running large current and voltage values through a phantom loop. Get some firebrick, and big pieces of copper that are about in diameter to regular copper piping, hook up a generator and set the copper rods having a centimeter or so of space between them, and run the current through! I probably shouldn't have said that. I hope nobody dies. Extremely dangerous. But that's how you make nanotubes and fullerenes, at home! Its probably illegal too, because of the "touch-the-wrong-place-and-you-die-effect." -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 07:53, 1 May 2006 (UTC)
I have a friend who's banned from a nearby institution because of an "incident" involving nanotube generation and the apparent destruction of some lab equipment. He's been asked not to return, to use his words. Isopropyl 22:17, 1 May 2006 (UTC)
I also remember reading some article about using a Laser on a sheet of very pure, very clean graphite. Seem to recall it being in Japan. It might've been related to making C70 instead of C60 though, it was 4 years ago at least. SanderJK 23:32, 1 May 2006 (UTC)
Buckminsterfullerene occurs naturally in soot, although I'm not sure why. Ardric47 00:02, 3 May 2006 (UTC)
  • Basically because of the principle that if you throw enough bombs into enough piles of bricks, one of them will sooner or later form a house :). Basically they're formed at random at high enough temperatures, when you have enough carbon atoms whizzing around, most of them will link up and form graphite, but a few of them will become various kinds of fullurenes and nanotubes. So the rest is a matter of filtering them out (as mentioned above). There is currently no good, ordered way to synthesize them. But you can safely say it's only matter of time before someone finds a catalyst, since there's a huge amount of people working on this. --BluePlatypus 23:03, 6 May 2006 (UTC)

Mysterious line of skin[edit]

I dont now much but i am kind of concerned because i dont now what is wrong with me; my foreskin is retracted, but not past the head, and a line of skin runs from the base (on the underside) of my shaft to near the opening which connects the shaft to the skin. it is visible on the outside of the skin. Please help.

I am a virgin and a recent teen (i've been a teen for a couple years) --216.197.192.136 03:06, 1 May 2006 (UTC)

Sounds like your frenulum. I used to have one myself. Scared the shit outta me when it snapped. Howard Train 05:29, 1 May 2006 (UTC)

Doesn't that come with birth (the frenulum)? What do you mean you used to have one? AHHHHHHHH!! OMG WTF, the 4th time I read the above comment, I read that it snapped! Ahh! Owwwww. Owww!!

Anyway, to the question-poster: Does it stick out, three-dimensionally? How is it different from the surrounding? When did it appear? You're about 14-16? -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 07:58, 1 May 2006 (UTC)

If this is something you're worried about, may I suggest you talk to your doctor? There is no need to be embarassed about asking, doctors have seen all manners of things, and s/he will be able to help you if there is something wrong, or put your mind at rest if there isn't. Remember, we're not doctors :) — QuantumEleven 08:46, 1 May 2006 (UTC)
Seems that what you see is the penile raphe. The scrotum and foreskin are formed from tissue that in women would form the inner and outer labia. The ridge is where they have fused. Nothing unusual there, mate! Dr Zak 11:30, 1 May 2006 (UTC)

Yah it's '3D', it just connects from by where the scrotom connects to the shaft and goes to near the tip of my penis. So nothing is bad about it though? I can live happy with it? i think it is a frenulum...

Yah, i google image searched it and it's a frenulum....

Pictures?[edit]

Are there any pictures on frog anatomy...or any other type of science-related subjects? Mostly people I know tend to be visual. Thanks!

Did you try frog? I mean, it's got the full skeleton. Isopropyl 05:54, 1 May 2006 (UTC)

General Relativity[edit]

I know that mass and energy warps space-time but why?

Unknown. Possibly due to entirely theoretical gravitons. If you can understand it try quantum gravity. -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 07:44, 1 May 2006 (UTC)
See General relativity. – b_jonas 11:36, 1 May 2006 (UTC)
déjà vu. -lethe talk + 16:39, 1 May 2006 (UTC)
Fundamentally asking 'why' about physical laws is not helpful. Physical laws are descriptions of the way things are: asking why things are the way they are is the realm of metaphysics. DJ Clayworth 17:23, 2 May 2006 (UTC)

Naval Citrus Storage[edit]

How did the British Navy preserve lemons and limes that were used in preventing scurvy? A lemon may last several weeks if kept in ideal conditions, but it seems that the time between the fruit being plucked from the tree and the time it was delivered to the sailors would be a few months, or maybe even as long as half a year. The lime or lemon would have to be harvested, packaged, shipped, and stored before being finally served. Packing it in salt would just draw out all of the fruit's moisture. Does anyone have an answer?

--Sputnik

On a History Channel show, I remember that on one British naval exploration voyage to explore Canada, they used canned lemon juice, and had excessive amounts of it. But one of the downfalls of the mission leading to its death, was that the compounds in the lemon juice brokedown, and most of them ended up dying of scurvy. I seem to remember that they grew lemon and lime trees on the boat itself. -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 10:59, 1 May 2006 (UTC)
...which creates another question. "Exploring Canada" and "growing citrus fruit": They'd have had fun growing lemon trees if this was one of the Northwest Passage expeditions! How the hell did they get things to grow in those temperatures? Grutness...wha? 13:28, 1 May 2006 (UTC)

You can water them with snow. --Zeizmic 17:33, 1 May 2006 (UTC)

Ha, ha guys. I meant on trips to the Caribbean [for the growing trees on the boat part] you silly heads! -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 07:49, 2 May 2006 (UTC)

MSN Messenger 7.5 annoying login problem[edit]

When I try to login in MSN Messenger, sometimes (most times) the window about the unread messages in my e-mail account pops up but the rotating icon keeps rotating, impeding me from viewing my contacts. Has anyone else experienced this problem? Does anyone know how to solve it? Thanks.

That's because its a Microsoft product. Use Gaim to connect to MSN. --Chris 13:14, 1 May 2006 (UTC)
If you want to stick with MSN, go to Tools -> Options -> Alerts and Sounds and remove the checkmark beside "Display alerts when e-mail is received" Andrewjuren(talk) 15:46, 1 May 2006 (UTC)

Relativity[edit]

Relativity often emphasize that the laws of physics for everyone are the same no matter what speed they are travelling at. Why is that?

Did you try principle of relativity? Isopropyl 12:33, 1 May 2006 (UTC)

The laws of physics are the same all over our universe( and probably all others if there are any more ). irrespective of what speed you or the observed object is travelling relative to each other. They are this way because if they were not the laws would not be universal.

In other words the universe would break down and implode or flash into non-exixtence, because the physical laws in zones with common borders would not be compatible. Some may say that the laws could be different if there were volumes of space containing nothing between different areas or universes.

This is also impossible for at least two reasons. 1. there can be no areas where 'nothing' exists ( neither time nor space) for the obvious reason that if there is no space there is no separation and 2. If there was something called space between the two areas then such entity would have its own border regions which must by definition come up against the formerly mentioned regions and therefore be in contact.

As you can see the speed of objects or entities does not have any real meaning in this context because

1.Even if the two objects were travelling say in opposite directions at the speed of light ( as in fact photons often do ) each would be travelling AT the speed of light relative to the other. They must by definition respond to the same laws of physics because even though travelling at light speed they would have at some time have been in the same area.

2.If they are travelling at different speeds, say one is 'stationary' and one travelling at 180,000 k p sec. in the opposite direction, then what happens ? If the laws were not the same we could not 'see' each other, obviously because we would not be using the same laws. If we did 'see' each other we would have to conclude that we were subject to the same laws. If we swapped places and we were then on the object travelling at 180,000 kps what would happen ? We would perceive that the other object was travelling away from us at that incredible speed and that we were stationary ( if we did not have any other reference point which was within our sphere of observation )

You can also ask the questions: a) what happens when the two entities are travelling toward each other ? b) Which one is moving ?

--Antipodeite 13:37, 8 May 2006 (UTC)

Synaute[edit]

Is a synaute a real thing? zafiroblue05 | Talk 12:44, 1 May 2006 (UTC)

Very good question. it looks plausible, but (other than Wikipedia mirrors) gets virtually no google hits. I've sent it to Wikipedia:Articles for deletion where hopefully some people more in the know will be able to work out whether or not it's for real. Grutness...wha? 13:37, 1 May 2006 (UTC)
Yes, they are real things, only they are called cenotes.--Andrew c 20:49, 1 May 2006 (UTC)

i think people need to stop inveseting so much faith in the ridiculousness (sp?) of google. i could be mistaken but i believe it's filtered by republican war machines! but like i said i could be wrong....now off to macdonalds! PSYCH! peace -jms

Do you mean sign out ? That's a real thing !--Antipodeite 13:06, 8 May 2006 (UTC)

GSM v/s CDMA[edit]

in gsm technology, we have MSC codes(represented by first five digits of the 10 digit cellular number). what is the counterpart of this in the CDMA technology? is it diffrent in various parts of the world? if yes then , what is the trend in india?

dominic, new delhi.--210.210.24.146 12:55, 1 May 2006 (UTC)

I don't know whether we can help you on this highly technical question, but you might try our articles on GSM and CDMA. --Robert Merkel 01:49, 5 May 2006 (UTC)

Using a sextant instead of a GPS receiver![edit]

Is it possible to use sextants or similar low-tech tools for Celestial_navigation in an activity like geocaching? The accuracy of many GPS receivers is about 3 metres. What would be the typical accuracy of using astronavigation techniques? Does it even come close to 3 or 10 metres or is it too fuzzy to use for geocaching? --Sonjaaa 13:19, 1 May 2006 (UTC)

I'm certainly no expert, but I'd be extremely surprised if you could get closer than a couple of kilometres to absolute accuracy with a sextant alone. In the days when they were the principal form of navigation, they were used (a) in the open sea, where absolute accuracy was not necessary, (b) close to or on land, in which case triangulation using major points of reference provided an important secondary tool and would be able to provide far greater accuracy. I certainly wouldn't think you could use astronavigation alone for geocaching, though a combination of it and triangulation from landmarks might get you fairly close. Grutness...wha? 13:46, 1 May 2006 (UTC)
While doing things the old way might be an interesting diversion for modern geocachers, the same problem faced polar explorers, particularly those hoping to be the first to either pole. A sextant is indeed much too crude, but celestial navigation is the only option - there's no maps (so no known landmarks against which to triangulate) and magnetic compasses are useless at such extreme latitudes (indeed, beyond the 80th parallel they're pointing in entirely the wrong way). Amundsen (at least, probably others) did use dead reckoning as a backup (a spiked wheel on one sled turned as it moved over the snow), but the irregularities and twistiness of the terrain make that only of moderate use. It's an interesting question to ask "who was the first person at a given pole" - how close does one have to be for it to count? Amundsen and Scott both took with them fairly bulky instruments (theodolites, I suppose) such to measure the precise location of the sun (remember also that they did their explorations in the antarctic summer, when the sun never sets, so there are no sunrise and sunset measurements to be had, and the stars are never visible). I imagine these were fitted with some form of tunable slit to allow the position of the sun to be precisely captured (when you get to the degree(sic) of accuracy needed, the apparent diameter of the sun will itself be an issue - so you'd need to measure the position of the left and right edges of the sun (hence the slit) and average the two). I believe (from my recollection of Roland Huntford's Last Place on Earth) that these observations (and the subsequent hour or so of calculations) were done only once per 24 hour period, except when they were very near the pole, when it was necessary to conduct them almost continually. Amundsen camped where he thought the pole was, but moved the following day (after extra detailed observations and calculations) showed it to be more than 1 km away. Even then, modern astronomers examining his logs and recalculating his position with more accurate tables think he was still about 1km off, and that two men in his party (when trekking from one camp to the other) probably came to about 300m of the actual geographical pole. And remember that Amundsen had a master's certificate and both Helmer Hanssen and Sverre Hassel mate's certificates, so a more experienced bunch of celestial navigators you'd not find. It's a remarkable feat of celestial navigation, but still too poor for geocaching, I think. -- Finlay McWalter | Talk 14:57, 1 May 2006 (UTC)
Even if the stars were not visible, I suppose the Moon would still have been visible some of the time, and it could have helped them slightly. – b_jonas 00:03, 2 May 2006 (UTC)

Torge, Wolfgang. Geodesy (3rd Edition ed.).  mentions the accuracy of some observational instruments. For stationary observation the Danjon prism astrolabe achieved a precision of ±0.05". For field measurement, transportable instruments mentioned are: prism astrolabes, zenith cameras (±0.5" or better) and the universal instrument (a theodolite with attachments for astronomic observations, ±0.1" to ±0.3".) All these instruments require a very accurate integrated time source, synchronized with International Atomic Time. EricR 16:36, 1 May 2006 (UTC)

making map pictures for wikipedia?[edit]

I want to add an image of Leslieville to show the boundaries of the neighbourhood, can I use google maps or if not then what online mapping source can I legally use to make the image, showing all the streets and the boundaries?--Sonjaaa 14:34, 1 May 2006 (UTC)

No, you can't use google maps in wikipedia, either directly (by including the image) or indirectly (by tracing over a google map) - the maps are copyrighted by Google and its partners, and certainly aren't compatible with the GFDL. See Wikipedia:WikiProject Maps for links to resources for drawing your own map; suffice it to say that it's hard. -- Finlay McWalter | Talk 15:02, 1 May 2006 (UTC)
That's strange that tracing is not allowed (even from satellite view?). Does it mean that Google basically owns the shapes of streets in Toronto, for example?--Sonjaaa 15:33, 1 May 2006 (UTC)
No, you could go out into the street with surveying equipment and measure it yourself, and that would be perfectly legal. But maps are certainly copyright, as are photographs (and a tracing, as a derivative work, is still the copyright of whomever took the original photo/survey). It's questionable if you could really get caught tracing a google map, but remember that the map projection is specific to Google, and mapmakers are notorious for deliberately introducing small errors into maps to catch copyists. Now, there are PD satellite and aerial photos, so you could either use those or trace them. Things are particuarly nice for the US, because NASA World Wind will retrieve free USGS topographic maps, landsat photos, and (for major US cities) detailed aerial photography. All of that stuff is public domain, and can be used in Wikipedia directly or as the basis for composites, diagrams, maps, etc. But for Canada all worldwind will give you is the Landsat imagery, which (at 15m I think) is much too chunky for street-level stuff. Natural Resources Canada has some information here, but I don't know how detailed their stuff gets. Urgh, on checking their page even that is non-commercial-use only, which still means it can't be used on Wikipedia. -- Finlay McWalter | Talk 15:47, 1 May 2006 (UTC)

Ontario has digital base maps here [1] I just emailed them to check the public domain status, since I don't see anything on the web site. --Zeizmic 15:48, 1 May 2006 (UTC)

One thing that can be done is to compile an approximate map using GPS data. Image:London Underground Zone 1.svg is one such (the underground map of London), which was compiled by wikipedians with handheld GPS units and some software to bold the whole thing together. An impressive piece of work, but still a lot of work. -- Finlay McWalter | Talk 15:50, 1 May 2006 (UTC)
If i trace a map from Google..how will they know that i traced it?? Jayant,17 Years, Indiacontribs 16:07, 1 May 2006 (UTC)
As the recent Dan Brown copyright case shows, if a copyright case comes to court the creator of the contested content will be asked to prove they really created what they say they did. It's quite reasonable for a court, at some future point, to ask "where did this map come from?" Google (well, their suppliers) can show they made their map, because they have the original survey notes of the surveyors. If you traced a map or satellite photo, you can't produce such notes. "How", you might ask, "would Google or anyone else become so suspicious so as to sue in this manner?". Firstly, Google don't own most of their mapping data - they buy rights from regional mapping agencies - and for many regions, only one company (often a division or agency of the government) has actually done the on-the-ground survey. Say, for example, if someone uploaded a street map of a city in the UK. Bar a very few places, that original data has only ever been mapped by the Ordinance Survey - so the very fact that the map is fairly accurate is enough to make the OS's flesh-eating lawyers suspicious. And secondly, as I noted above, cartographers often put little errors into maps - if the error shows up in your map, it's strong evidence you copied the map. And don't for a moment imagine the satellite images Google shows haven't been montaged, adjusted, and potentially tweaked in just the same manner. Anyway, it's a very bad mindset for a Wikipedia contributor to be in when they're thinking "how can I sneak in copyvio stuff and get away with it?" -- Finlay McWalter | Talk 16:25, 1 May 2006 (UTC)
I wasn't thinking on those lines anyways.. was just wondering... Jayant,17 Years, Indiacontribs 17:08, 1 May 2006 (UTC)


Neat, I also found this: OpenStreetMap --Sonjaaa 18:21, 1 May 2006 (UTC)

Does it mean that I can't use Google earth pictures in my website, even if I don't make any money out of it ? Say I use a high resolution map of a city and lable the streets etc and display it so that it is helpful for others to find their way around ? If i really want to do it, can I get google's permission ? How do I get it ? --Wikicheng 18:26, 1 May 2006 (UTC)

I just got the standard answer back from the Ontario gov't: "These maps, and maps you make from them, are mine, mine only, and always mine!" There is no such thing as public domain in Canada, unless you are talking about a neato 1885 map of Ontario. --Zeizmic 18:51, 1 May 2006 (UTC)
Copyright is copyright: "I don't make any money out of it is" absolutely no legal defence. Imagine if you duplicated Disney's latest DVD and gave away copies. Would you make money? No. Would Disney sue you for every penny you owned, and a lot you didn't? Sure would. Similarly "being helpful" isn't a defence for copyright theft. Maps cost millions and millions of dollars to make, so the people who make them are every bit as keen as Disney to stop theft. Please stop looking for loopholes, you are doing yourself no favours! If you want to license content from Google, start by sending them an e-mail; but since Google in turn license their maps from other people they might not be able to sublicense to you. However, many parts of the world are covered by people who will allow limited use of their maps, in return, perhaps for a credit, or at least allow you to link to a small part of the map. For example, http://www.streetmap.co.uk/linkto.htm explains how to link to their maps of the UK, while http://www.ordnancesurvey.co.uk/oswebsite/getamap/ allows you to download up to 10 UK maps for use on your web site free (subject to terms and conditions including a particular form of credit with a link back to their site. Notinasnaid 18:58, 1 May 2006 (UTC)
Just let me note that you can read the exact Terms of Service for Google Mapsb_jonas 23:58, 1 May 2006 (UTC)

What about this?? http://geodepot.statcan.ca/Diss/2006Dissemination/Data/download_e.cfm Maybe we can use this data for a map of Toronto neighbourhoods? Do we have permission?--Sonjaaa 19:16, 1 May 2006 (UTC)

Does the web site give you permission? If you aren't sure, but it seems to, please post the URL of the information in doubt. Notinasnaid 20:04, 1 May 2006 (UTC)

Although this is depressing, throughout Canada, you will find the same thing. If you email them, you will get the 'crown' speech that I got. Only if they proudly splash 'public domain' on their web site (as the National Archives) are you in the clear. --Zeizmic 01:50, 2 May 2006 (UTC)

I don't find it depressing. I'd rather the Ordnance Survey made its money by commercial licensing of the results of its work, rather than pay more taxes so they can give it away. Notinasnaid 10:47, 2 May 2006 (UTC)
I thought I'd add a little more, since I've been reading the accounts of the Ordnance Survey. In 2004-5, it cost 105 million pounds to run the Ordnance Survey, but the total of government grants was 1 thousand pounds. All thanks to the wonder of copyright! By contrast, the United States Geological Survey (which admittedly does more than maps) has a government budget of $938 million. Notinasnaid 22:28, 2 May 2006 (UTC)

Let me assure that being a wikipedian I wasn't planning to misuse the google map. I just thought that it would be useful to setup a website which would allow people to navigate thru a city easily. Definitely not looking for loopholes ! My apologies if I sounded that way. Well... I may write to google and see what they say. Thanks for all the info and help --Wikicheng 12:08, 2 May 2006 (UTC)

Voltage Coversion with a small elecronic appliance[edit]

I live in the USA and am taking my USA Digital Canon Rebel XT to Europe this summer. Ordinarily I would take a voltage converter but the specs on the back of the battery charger say the "input" is 100V - 240V so I am thinking that other than the issue of incompatible prongs, I could theoretically use this charger without converting the voltage (just perhaps get an adapter so the USA prongs can fit into a European outlet). Doesanyone have any knowledge about the implications of the specs on the charger? Do you know anything about the Rebel's battery charger? (It is the CB-2LT charger).

You could just use a plug converter for the 50,000 different plugs in Europe. I would definitely use an external charger, since I hear they get power spikes when they change hamsters. --Zeizmic 15:18, 1 May 2006 (UTC)
Zeizmic is quite clearly a complete bell end. Let me re-phrase that for you;
You could just use a plug converter for the 3 different plugs in Europe. I would definitely use an external charger, since I hear they get power spikes when america declares war on another innocent country. Philc T+C 16:45, 1 May 2006 (UTC)
Thank you for standing up for us, PhilC :). Just to be sure, make sure that your charger also takes 50-60 Hz current (US is 60Hz, Europe is 50Hz). If it's 110V-220V it almost certainly will, but you want to make sure. As for plus, your best bet is one of those 'universal' adapter plugs they often sell at airports (although they're not always cheap). Alternatively, which country are you going to? Take a look at Electrical plugs: Most of Europe uses a type C, except for the UK and Ireland, which use a type G. In Italy and Switzerland you'll still find some type L sockets, but most hotels will have converters in stock so you can use a type C. Hope this helps! — QuantumEleven 13:06, 2 May 2006 (UTC)

Television set from USA to India[edit]

Hi i have a used Toshiba television set from 1997 which has only Closed Captioning and no fancy features. i plan to take it to India. i understand that the US has NTSC colour television system while India has the PAL colour television system. Is there a way that the television set would work in India? [++ Any specific knowledge of duty at Indian Customs would be welcome too ++]

Regards Babbu

See NTSC and PAL. As discussed here previously, if you try to watch a PAL program on an NTSC set, you will get a fuzzy gray image that rolls every few seconds. There are PAL-to-NTSC converters, but they cost far more than a new PAL television. All in all, you'd save a lot of money by leaving (or selling) the NTSC tv and buying a new PAL tv in India. --Kainaw (talk) 16:27, 1 May 2006 (UTC)
Worse, as India has 230V mains and the US 110V, it'll probably burst into flames as soon as you plug it in (so you can't use it even with a US DVD player, unless you wasted more money on an expensive voltage-transformer). Anyway, surely the cost of shipping would cost more than the price of a new TV in india. -- Finlay McWalter | Talk 16:33, 1 May 2006 (UTC)

Dear Kainaw and Finlay McWalter
Thank you very much for your prompt and informative replies and apt suggestions. i will certainly do as you say.
The shipping for the TV would cost over $300.
Regards, Babbu

Simple Carbohydrates in a Packet of Sugar[edit]

Hi there,

I was wondering how many carbs are in a packet of sugar. Or Even easier, how many grams of sugar are in a packet, because I have a carb count for 100 grams of sugar but I don't know by what to divide it.

Thanki

Why don't you look under the "nutritional information" of the packet and look. Looking at my bag of granulated sugar, per 100g of sugar = 100g carbohydrates; one serving (amount not specified) is 4g of carbohydrates. Kilo-Lima|(talk) 16:51, 1 May 2006 (UTC)
That would knda mean one serving is 4g of sugar -- is this some sort of trick question? Sugar is 100% carb; that's kinda the whole point. --jpgordon∇∆∇∆ 01:05, 2 May 2006 (UTC)

A restaurant packet of table sugar is typically 1 teaspoon of sucrose, equal to 4 g or 16 cal. Sucrose is 100% carbohydrate, readily digestible to about 50% glucose and 50% fructose. alteripse 05:15, 2 May 2006 (UTC)

Army pay for medical studies[edit]

I need to find information on army paying for my medical studies. I heard that the army pay for you university studies if you join the army for a short period. Does anyone know a good website to find information on this? I am looking for information for british universities.

Cheers

Please remember to sign all of your posts on talk pages. Typing four tildes after your comment ( ~~~~ ) will insert a signature showing your username and a date/time stamp, which is very helpful. Also, it might help if you said what army you mean (the British one?) Sandstein 19:49, 1 May 2006 (UTC)
  • I would recommend calling the army in question and asking. --Ginkgo100 19:53, 1 May 2006 (UTC)

Google is probably your best bet. I'd advise against speaking to recruiters as they're notorious for over-hyping military scholarship programs (at least that's the case here in the U.S.). Best, David Iberri (talk) 21:23, 1 May 2006 (UTC)

Stars n Universe[edit]

Since stars work out by Hydrogen fusion and at later stages Helium and then much heavier atoms as it begins to collapse, but where do atoms aobve the weight of iron come from, because only hydrogen was created in the big bang, so where do the heavier atoms come from since it becomes energy-wise unprofitable to fuse atomic nuclei beyond iron.

Also once a predominant amount of the nuclei have gone through whatever process is the answer to the question above, will stars cease to exist, or will there be fission stars, or what. Cheers Philc T+C 16:36, 1 May 2006 (UTC)

Q1: See nucleosynthesis and supernova nucleosynthesis.
Q2: See Ultimate fate of the universe. TenOfAllTrades(talk) 17:29, 1 May 2006 (UTC)
I couldn't really find anything about the fate of stars after large amounts of the matter in the universe make up atoms heavier than iron in Ultimate fate of the universe or wether fission stars are possible. Does anyone know the answer, or could point it out to me. Philc T+C 17:58, 1 May 2006 (UTC)
See uranium. It is a very plentiful material on Earth. It goes through natural fission on the Earth - enough to affect the core tempurature of Earth. So, if you define a "fission star" as something that floats around space and contains some material that goes through natural fission, then Earth is an example of a fission star. As for your assumption that Stars will eventually use up all the hydrogen in space, you are assuming that there is no source of hydrogen. Why can't there be fission going on all around space. There is certainly enough radioactivity to get things going. --Kainaw (talk) 18:17, 1 May 2006 (UTC)
I think he is thinking of a more intense and larger reaction going on than simple, small, localized reactions taking place on a tiny rock. That's a good question—the possibility of a fission star—I'd day no. Because in what I've read, I've never heard it mentioned. -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 20:51, 1 May 2006 (UTC)
I wouldn't of thought it was naturally possible after considering it for a while, for a star sized mass of such high concentrationns of heavy elements such as uranium to form. So although it is unlikely to ever occur, as a thought, would it be theoretically possible, and how would it differ from fusion stars (eg, nuclei created by fission tend to have huge half lives, whilst nuclei created by fusion have relativly minimal ones, so if it supernovad, would a fission star polute space or something) Philc T+C 17:56, 2 May 2006 (UTC)

As I understand it, the fuller cycle seems to be, and this is a laymans understanding only in outline:

  • Theres a huge amount of hydrogen in space. The mechanism for stellar formation and conversion for elements from fusion, from lighter to heavier, from hydrogen to to helium and up to around iron, is reasonably understood. After that point, usual stellar processes by means of atoms combining, cease to be net producers of energy and become net consumers, so heavier elements cannot form in that way.
  • As this happens, the star which has been burning hotter, cannot sustain its power output, and the immense pressures generated by this heat cannot counteract gravitational collapse. So (a sufficiently massive) star collapses somewhat, and sits there glowing as a dwarf star. Presumably it may become a nova for a time too.
  • A sufficiently large star has such a mass, that gravity itself can overcome the remaining pressures. The forces that prevent collapse above, are overcome, and the star may become a neutron star, or collapse and then explode as a supernova.
  • In this final collapse, forces other than nuclear fusion are at work, mostly driven by the immenses force of gravitational collapse. It is my understanding that this is the environment in which heavy elements beyond iron are formed and exploded out into the universe at large.
  • So in a nutshell, lighter elements are created by the fusion reaction of smaller atoms combining into more stable medium sized ones, and heavier atoms are created by gravitationally driven collapse. So ultimately, the energy given off by elements such as uranium, comes from gravitational energy which has been "used" to form unstable heavier elements that then in turn decay giving off energy themselves as they revert to more stable forms.

Hope this helps, and if it's roughly accurate add it to some appropriate article on creation of elements or stellar processes. As said, its my lay-understanding only, but I think its roughly ok as a broad non-technical answer. FT2 (Talk) 15:09, 2 May 2006 (UTC)

DNA synthesis techniques (also Protein synthesis)[edit]

Does there currently exist a technique which permits the synthesis (as opposed to the sequencing) of a specific desired strand of DNA or RNA of known sequence, presumably using its base nucleotides? If so, how does this work and what are the limitations of the technique? As this might be a lengthy answer, a very brief explanation and a reference for more data would be terrific.

(I am already familiar with PCR, and using and selecting an existing sequence/allele for amplification or expression in-vitro. I am curious about synthesizing very long strands or sequences which may not be found in nature.)

As a correlary, is there a simple, high-yield, automated process for protein synthesis from its amino acids? Especially for longer, more sophisticated proteins?

Thank you very much for your help. :)

--216.226.42.167 17:11, 1 May 2006 (UTC) Alaiyo

Do your own homework. And for that matter, I think the answer is no. We can splice, cut, alter, but not create DNA/RNA.--Frenchman113 on wheels! 17:23, 1 May 2006 (UTC)
My apologies.--Frenchman113 on wheels! 22:07, 2 May 2006 (UTC)
Don't bite the newcomers—his doesn't look like someone looking for us to do his homework; he's just looking for pointers. Worse, your answer is incorrect.
Short strands of DNA (up to a couple hundred of bases in length) are regularly synthesized for all kinds of purposes. These oligonucleotides (usually just called 'oligos') are often used as PCR primers. Google for 'DNA synthesizer' to find commercial equipment and information.
Since synthesizing really long strands of DNA artificially tends to be error-prone, you can sequentially stitch together shorter oligos using DNA ligases to build entire genes from scratch.
For proteins, a similar process can be used. (Different reagents and equipment, but similar concepts.) Protein synthesizers (again, Google for them for more info) can sequentially ligate amino acids to build an artificial protein. However, this works well only for relatively short sequences. 20 amino acid residues usually works fairly well; 30 is about the limit. Again, it is possible to ligate these chunks together, but it's more difficult than with DNA.
Trying to synthesize a larger protein in this way isn't – as far as I know – possible. Your synthesis and ligation yields get too low. Also, getting a large protein to fold properly usually requires chaperone proteins that won't be present in your system. TenOfAllTrades(talk) 17:52, 1 May 2006 (UTC)
Ten is correct. There is active debate in the synthetic biology community as to whether or not DNA synthesis should be regulated, as the sequences of many known human pathogens are available online. These include extremely infectious diseases that are otherwise difficult to acquire, such as smallpox or the previously extinct 1918 influenza virus. As the technology stands today, costs for synthesis hover at around one dollar per base pair, which is prohibitively expensive beyond a certain point. Worse yet, not every sequence can be successfully made (for a variety of reasons) which leads to enormous time sinks as orders come in, weeks are wasted trying to synthesize them, etc. Hope this helps! Isopropyl 22:01, 1 May 2006 (UTC)

Thank you to the both of you who offered me a nudge in the right direction. Yes, I am a newcomer, I am also a "she", and I had a brainstorm the other night on overcoming some of the protein synthesis challenges to which you alluded. DNA synthesis seemed like a reasonably obvious extension of the problem. Your leads (and admonition for caution in terms of safety/socio-economic implications) are very helpful. Have a terrific day!

Ingredients of "parfum"[edit]

Recently i purchased a deo which states under the ingredients list the following "alcohol denat" & "parfum". I read the comprehensive article with regard to "alcohol denat" in wikipedia site and all he ingredients used in making it, but was unable to find out the same with regard to "Parum" Please help me to get the ingredients used in making the same.

"Parfum" is French for "Perfume". It means "artificial scent". This is similar to food that lists "artificial flavors" in the ingredients. So, you won't find the specific ingredient used. --Kainaw (talk) 18:42, 1 May 2006 (UTC)


thanks for the reply, but a small clarification, i read in an article that there are two kinds of alcohol used in cosmetics and perfumes (1) alcohol denat (2) alcohol parfum. if parfum is french for perfume then what is alcohol parfum?. appreciate your views on this

"Alcohol perfume" is basically grain alcohol (190 proof). "Alchohol denat" is short for "denatured alcohol". A denatured alcohol is poisonous, which means that it falls outside of laws governing alcohol that you can drink. There are governmental laws and religious laws governing alcohol usage. By using denatured alcohol, perfumes get the benefit (the perfume evaporates faster) without the legal/religious hassles. --Kainaw (talk) 20:39, 1 May 2006 (UTC)
Denaturated alcohol is not actually poisonous, at least not more so than ordinary alcohol. It is just undrinkable, usually through adding Bitrex or some similar substance which tastes horrific even in trace amounts. Chemistry lab ethanol can be quite toxic though, in particular the "dry" kinds (with concentrations above the water azeotrope at 96%). Those often contain drying agents like Bromobenzene, which react with water. For use as a solvent in things like Grignard reactions when you absolutely do not want any water present. --BluePlatypus 22:55, 6 May 2006 (UTC)

magnetic north[edit]

If you travelled into space with a compass which way would it point once you'd left earths atmosphere??

It would still point along the magnetic field lines; see Earth's magnetic field and Magnetosphere for rough depictions. Melchoir 20:45, 1 May 2006 (UTC)
The Earth's magnetic field extends well past the atmosphere. Magnetosphere. However if you got far enough away from the Earth other planet's or the Sun's magnetic fields would be where you compass would point to. -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 20:47, 1 May 2006 (UTC)

BP suffix on medicines etc.[edit]

Why is it that some medicines have their name, for examples (this is made up) Magensium Hydrochoride BP. What does this stand for if anyone knows? Thank you

BP is short for benzoyl peroxide. --Kainaw (talk) 20:41, 1 May 2006 (UTC)

What is that exactly? Is it a preservative or just a solvent for the drug to be in a solution form? Thank you for the hasty reply.

On a medicine bottle, specifically following the name of the chemical, BP is short for British Pharmacopoeia. Notinasnaid 20:47, 1 May 2006 (UTC)
See benzoyl peroxide. It is a popular medicine for acne and teeth whitening. The initials "BP" commonly follow many acne medications to signify that benzoyl peroxide is the primary ingredient, such as Xerac BP. --Kainaw (talk) 23:24, 1 May 2006 (UTC)
Except I have medicines where it seems unlikely to signify an ingredient. For example, in the ingredients list it will say "Hydrocortisone BP 1% m/m Also contains white paraffin." In this case, Notinasaid's meaning seems much more likely, and seems to match the example. If I ever see it following the name of a tooth whitener or acne treatment however, I shall be sure to remember benzoyl peroxide. Skittle 01:39, 2 May 2006 (UTC)

BP does stand for British Pharmacopoeia. The comparable label in the US is USP, which stands for United States Pharmacopoeia and indicates that the product meets the specifications of the USP. This is normally used of older generic products (e.g., aspirin or Epsom salts) that you might consider "medicinal chemicals" rather than patented pharmaceuticals. alteripse 05:11, 2 May 2006 (UTC)

I've edited BP (disambiguation) to try and explain all this. Melchoir 05:34, 2 May 2006 (UTC)

Physics: Air friction in a hollow ball?[edit]

You have two balls perfectly next to each other on a perfectly smooth slope. Both balls are of exactly the same composition. When you roll the balls at the same time down the slope, they should both travel at exactly the same rate. Take the same situation, but this time make one of the balls hollow. Will the hollow ball be slower than the other because of friction from the air inside? Or for any other reason? Flea110 21:00, 1 May 2006 (UTC)

My guess is the 'friction' from the air inside would be minimal, the hollow ball would be lighter than the solid ball. Since it has the same surface area as the solid one it would be slower due to air friction of the air OUTSIDE.

Air resistance isn't really a factor here. Take a look at moment of inertia and see if you can figure it out. If not, we'll be happy to help you :) Isopropyl 21:34, 1 May 2006 (UTC)
Okay, so you're familiar with the concept of inertia, right? An object at rest tends to stay at rest. The moment of inertia is another way to measure inertia, only around an axis with rotation. You'll find (from list of moments of inertia) that hollow spheres have a greater mass moment than solid spheres, and thus have a harder time "getting the ball rolling", as it were. Your solid sphere will roll down the ramp faster. Isopropyl 22:10, 1 May 2006 (UTC)
True, for two spheres of the same mass but with the mass arranged differently within them. It occurs to me that Flea110 might be thinking about a case where the density of the material we're making the spheres out of is a constant, in which case it'll depend on how hollowed out it is. According to the back of my envelope, if the radius of the hollow region is more than 73.6% that of the total sphere then it'll have a lower moment of inertia than the solid sphere. --Bth 09:00, 2 May 2006 (UTC)
I did not believe Isopropyl at first either, but looking at the energy of the spheres at the top and bottom of the ramp: \frac{1}{2} mv^2 + \frac{1}{2} I \omega^2 = m g h If the angular mass is in the form kmr² and the translational velocity is related to the angular velocity by v=2πrω, then the mass and radius of the sphere cancel out. \frac{1}{2} v^2 (1 + \frac{k}{4 \pi ^2}) = gh EricR 15:58, 2 May 2006 (UTC)

Simple test for sugar?[edit]

Is there a simple test for the presence of sugar? I've been buying Nesquik made with Neutrisweet for years, but I bought some that has the appearance, texture, and disolving qualities of the sugared kind. I wrote tothe company about this, but they didn't understand what I was talking about. So is there a simple household test for the presence of sugar? Bubba73 (talk), 21:18, 1 May 2006 (UTC)

Why don't you try out the Sugar's chemistry for the chemistry of sugar. General Eisenhower 21:28, 1 May 2006 (UTC)
Not helpful. If you think a difference between the two types of nesquik include a reducing sugar such as fructose (look on the labels) you could test using Benedict's solution if you can get any. That article lists common sugars it detects. However, it's more likely you need a test for sucrose, and I can't remember or find one. I'll have another look. Meanwhile, just get clear and firm with Nestle. You bought a product labeled as sugar free, but you suspect it is the version with sugar. They may have a packing or labelling problem. Suggest you are diabetic :-) Skittle 22:58, 1 May 2006 (UTC)
I am, that's why I use the suger-free version. I think it is probably labelwd or packaged in error. I wrote back to them today. Bubba73 (talk), 23:09, 1 May 2006 (UTC)
Okay. If the difference in ingredients is sucrose, and you can get your hands on benedict's solution and fairly weak hydrochloric acid, then it should give a negative result to benedicts solution at first, but a positive result if it's been boiled with hydrochloric acid for a few minutes. However, since you are in America, there's a good chance that the sugary version is made using high fructose corn syrup, so it will test positive using Benedict's. If you buy some more sugar-free stuff, with a different batch number, and look at the label finding no reducing sugars, and test it with Benedict's and find it negative, then there you go. However, much better to complain effectively, send your sample and get reimbursed. In my experience, food companies (especially big ones like Nestle) will give you the benefit of the doubt quite quickly and try to sweeten you up with vouchers. They will also want to check your product so they know whether they need to issue a statement and a recall. Skittle 23:13, 1 May 2006 (UTC)
And you've probably already tried this, but you might get a faster response if you email them [2]. Good luck. Skittle 23:18, 1 May 2006 (UTC)
Actually not. I emailed them at first, and I got this reply on April 19: "Thank you for contacting Nestlé on the Internet. Questions and comments from our consumers are always welcome!... We reviewed your email and will be responding to your request via regular mail. You can look forward to receiving a written response from us within 7-10 business days.". Today I get the letter in the mail (and it was from the same person). Bubba73 (talk), 23:48, 1 May 2006 (UTC)

Identifying a flora or fungi from SE Arizona[edit]

I have uploaded a photo of what I thought was perhaps a mushroom of sorts. I have since looked through a catalog of fungi photos and saw none similar. The fellow in the photo felt smooth, cool, and mushroom-like to the touch. It grew near or in decaying organic material in the shade. Does anyone know what it is?

Thanks for your attention. This is a great service. I used a hyperlink rather than the Image: in brackets because I didn't know if it was acceptable to actually display an image on this page. Hope that is okay.


What am I?

--Bad carpet 21:45, 1 May 2006 (UTC)

I don't think it's a fungus, since they look like they have some sort of flowering apperatus at the top? I'm not sure. What I am sure about, though, is how to link to an image without displaying it. You'd use [[:Image:Unknown_SE_AZ_April_29_2006.jpg]] to produce Image:Unknown_SE_AZ_April_29_2006.jpg. Note the leading colon. Good luck with twenty questions! Isopropyl 21:50, 1 May 2006 (UTC)
  • I'm no botanist, but it looks like a match to me.--Ginkgo100 03:44, 2 May 2006 (UTC)
  • Props for the quick find :) Isopropyl 05:45, 2 May 2006 (UTC)

Gotta use the image for something: Conopholis. Melchoir 06:43, 2 May 2006 (UTC)

Looks like it to me. Thank you! --Bad carpet 16:17, 2 May 2006 (UTC)

  • Also, thanks for using the image. --Bad carpet 23:24, 2 May 2006 (UTC)
    • Well... thanks for providing it! Props all around, have a drink. Melchoir 23:35, 2 May 2006 (UTC)
      • In case anyone is curious, from the description, it was a saprophyte of some sort, and just did a Google image search for saprophyte. Luckily, there aren't all that many, and most don't look anything like the cancer-root. Wonder why it's called that? --jpgordon∇∆∇∆ 02:08, 3 May 2006 (UTC)
        • Perhaps because it is a root parasite (which accounts for the unusual color -- lack of chlorophyll). This site says they are invariably found among oak trees at least in Illinois (there were oaks in the area where the photo was taken.) Also curious is the common name of the family it apparently belongs to, "Broomrape." --Bad carpet 21:57, 3 May 2006 (UTC)

Trying to find old (1988-1992 range) DOS computer game.[edit]

Hi all. I'm trying to remember the name of a DOS - CGA computer game I played back somewhere around 1988 to 1992, I forget the exact name of it.

It was called something *like* Starflight I think, but I found that one on the underdogs, and it's not it. It was similar in that it was a space game. You had a crew of 5 (or is it 6?) on your ship, and you had skills such as tactics etc for each person to go up in. On occasion you would land on a planet and go inside a structure. Inside the structure you would see the action in front of you, but then overlaid on that would be a small HUD-type display with the walls and such in blue. Your 6 crewmembers would be behind you in blue circles on the HUD as well, and then unknowns would appear as red circles. You could get weapons like laser cutlass, some kind of mace, but also some projectile weapons. One of the worlds you landed on had (3?) large towers (like 500+ stories), which were all "populated", but you were only interested in one particular area of one of them. Anyways, that's most of what I can remember. If someone wants some more details, or has questions, post and I'll try to remember some more. Thanks in advance. Aaronw 22:50, 1 May 2006 (UTC)

May 2[edit]

Digital Video Recording Systems[edit]

on a digital cmara what is the Diffrence between the NTSC and the PAL video recording systems... is one better than the outher for taking videos?

Have you browsed the articles on NTSC and PAL? One thing you really need to take into consideration: if you record something in PAL, it won't play back properly on an NTSC-only VCR, and vice versa. If you're in the US (and I assume you are), NTSC is the standard and I'd say it's best you stick with that. Confusing Manifestation 04:17, 2 May 2006 (UTC)

Microevolution & Macroevolution[edit]

I've heard some Christians and creationists claim that microevolution and macroevolution are separate and distinct from each other.They claim that all examples of observed evolution are of microevolution and that 'small changes do not imply large changes'.They also claim that there is a genetic barrier stopping organisms from evolving so far as to cross the species border.Are those claims true?

There's a lot of information at Macroevolution. Melchoir 03:51, 2 May 2006 (UTC)

thx much

Long answer short: No. But reading the article is good.

Cockroaches surviving nuclear explosions?[edit]

Sorry if this is a kind of stupid question. Is it really true that cockroaches have survived nuclear explosions? I've heard people joke that cockroaches will be the only things still around after we all nuke each other to death, but I was wondering if that was really true. I already checked the page on cockroaches and several pages about nuclear weapons, and didn't find this information anywhere. I did see that they could survive high levels of radiation, but would they survive the amount of radiation in a nuclear bomb?

Thank you!

Not really... see the explanation at Great Moments in Science: Cockroaches & Radiation. Wikipedia really ought to address this, since it's so widespread; I'm surprised it's not in Snopes. Melchoir 04:50, 2 May 2006 (UTC)
Nice link, the picture of Conan the Bacterium is now stuck in my mind forever. SanderJK 08:53, 2 May 2006 (UTC)
Dr Karl is a really good reference for many of those odd-ball science things. He's like the Australian Mythbusters/Julius Sumner Miller. Actually, I got a newsletter from Sydney Uni today with a version of that very GMiS topic. Confusing Manifestation 09:49, 2 May 2006 (UTC)
I think scorpions can survive 10x more radiation that humans... not really really related to the nuclear/radiation, though. Kilo-Lima|(talk) 19:04, 2 May 2006 (UTC)

PSOC to Pic Basic[edit]

I am vary competent in basic and decent at C programming languages. A fellow robot enthusiast had suggested I switch to PSOC programmable system for my robotic uses.. had any one else had any experiences with PSOC?? is it worth the switch?? SumoBotMaker 04:40, 2 May 2006 (UTC)

I don't have any personal experiance with those chips but if they offer features you wan't that the pics don't and the programming hardware/software isn't too expensive (or you can borrow it off this friend) then i'd give it a go. It's always nice to expand your options. Plugwash 18:37, 9 May 2006 (UTC)

Recommend a chemistry text![edit]

Hi all,

I'm looking for a good first-year-undergrad level chem textbook (or two, if it's impossible to get one that covers both organic and inorganic). My formal chemistry education goes up to A-level (about eight years ago), though I've done QM-of-the-hydrogen-atom what feels like a hundred times since. I'm looking to freshen up and slightly deepen my knowledge. Any recommendations? (Easily available in the UK is a bonus but not essential thanks to Amazon etc.) --Bth 07:51, 2 May 2006 (UTC)

I can recommend John McMurry Organic textbooks, if you get older editions (not that much difference) ago via amazon used they're quite cheap. (Though postage might be a killer) The books in general give a very good basis for organic chemistry. Unfortunately, it does not cover inorganic chemistry, i'm not sure what to recommend (I was taught inorganic using Shriver & Atkins, but that book is not so straightforward). SanderJK 08:50, 2 May 2006 (UTC)
Silberberg, ISBN 0072396814, is good for general chemistry. —Keenan Pepper 15:58, 2 May 2006 (UTC)
And there's a used paperback (Like New!) on Amazon UK for only £25 ... (or at least, there was). Thanks Keenan! --Bth 09:20, 3 May 2006 (UTC)

anthrax[edit]

can anthrax be used as a bioweapon?

Yes. See Anthrax#Biological warfare. In particular, the 2001 anthrax attacks used "weaponised" anthrax. --Bth 10:53, 2 May 2006 (UTC)

wierd skin problem[edit]

hello

i have a habit of chewing the skin near my nails.its like i cant think without chewing my skin.whats happening to me?

As per the disclaimer at the top of the page, you should speak to a medical professional if you're really worried about this. But nail biting (which this is considered a form of IIRC) isn't uncommon at all (the article contains both statistics on the prevalence and information on treatment).
Incidentally, this came up recently on the Miscellaneous RefDesk as to whether it counted as autocannibalism or not (it doesn't). --Bth 11:06, 2 May 2006 (UTC)
FWIW, I used to bite my nails and I'd bite the skin when I ran out of nails. Perhaps this is what you're doing? --Howard Train 03:56, 4 May 2006 (UTC)

Nuclear Fusion[edit]

Does all chemical reaction need an activation energy? If nuclear reactions need an activitation energy, what's the activitation energy for nuclear fusion? I mean what activates the hydrogen to collide and create and helium?

Nuclear fusion is not a chemical reaction, but a nuclear reaction. However, nuclear fusion does require a lot of heat to initiate. See nuclear fusion. -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 11:12, 2 May 2006 (UTC)
Yeah, nuclear fusion's the place to go, though I just want to correct another seeming misconception in the question: that "hydrogen" fuses to helium. Normal boring single-proton hydrogen doesn't fuse directly to form helium -- fusion experiments on Earth tend to use deuterium, tritium or helium 3 as fuel. In stars, the pp chain or CNO cycle are involved (in which some of the protons are converted to neutrons).
Just as an example, For a deuterium-tritium reaction the necessary energy is roughly 100 keV (about 1.6 x 10-14 J, tiny in everyday terms but huge compared to the equivalent for chemical reactions because the distances involved in nuclear reactions are so much smaller).
The energy needed can be provided by high temperatures and pressures (in stars and fusion bombs) or by various acceleration methods (in fusion experiments). --Bth 11:39, 2 May 2006 (UTC)

Physics[edit]

Coloumbs law gives us force of attraction between two particles(charged).Does that include their masses as well? How about if a massless particle (gravitron)were subjected to this postulate?

Coulomb's law is essentially analogous to Newton's law of universal gravitation, but it deals with the electromagnetic force, not gravitational force (see Force (physics)). It only takes into account charge-ness. Granted, the force on a massy particle will have a much bigger effect than that on a less-massy one, but that won't change the calculation of the force between the two particles. I don't believe that any massless particles have charges, but I may be wrong about that one. -- Plutor 11:29, 2 May 2006 (UTC)
I'm not sure what you mean by "bigger effect". For the same charge, you'd get a greater acceleration for a less massive particle, simply by F=ma. I can't remember any massless charged particles either (the W bosons are charged, but also massive), but since massless particles are constrained to move at lightspeed, you'd have to treat any interaction properly using QED. Which would be hard.
To go back to the other question: in general, you could get a correction for the gravitational force simply by adding together the Coulomb and Newton laws, but the correction would be tiny. Consider the fact that atoms are held together by electrical forces and are very small indeed -- gravity is so weak that an atom held together solely by gravity would have a size on about the same scale as the universe. Gravity dominates on large scales simply because on large enough scales the positive and negative charges cancel out, whereas gravity is always attractive. --Bth 11:46, 2 May 2006 (UTC)

Can nuclear power save the planet?[edit]

I live in the UK and here the debate about nuclear power seems to have entered a new era, with many people who would normally consider themselves "green" warming to the idea of nuclear, I suppose as a lesser of two evils. Meanwhile renewbles seem ever more remote as a possibility.

I would be interested to hear personal viewpoints on this from around the world. To phrase it as a question: Can nuclear power save the planet?

I'm in the UK and am fairly strongly pro-nuclear for the reasons you outline (incidentally, a leading proponent of this POV is James Lovelock, the Gaia hypothesis chap), though I have heard arguments that the extraction of nuclear fuel creates almost as much greenhouse emission as simple burning of an equivalent amount of fossil fuel, which would change the calculus.
I get very annoyed by many renewables advocates because so many of them who are pro in theory suddenly become anti in practice when someone wants to erect a wind farm within a sightline from their house. Terrible nimbyism. More general, the technology doesn't seem to quite be ready and AFAICS we need some sort of stopgap for another generation or so, either nuclear or carbon-sequestered fossil fuels. (From the security of supply POV, I'd choose nuclear.) Of course, the missing part of the equation is reducing the demand for power, at which we do an absolutely appalling job.
Having used your question to have a vent, I shall turn round and note that the reference desk isn't really for opinion polls. --Bth 11:38, 2 May 2006 (UTC)
When using "nuclear power" and "renewable power" in the same argument, keep in mind that nuclear power is a renewable power. Assuming that humans figure out how to fuse the nuclear waste back together, nuclear power will become twin fusion/fission reactors. Because fission reactions tend to create very nasty explosions right now, many refer to nuclear power as a non-renewable resource without adding the clarifier right now. Then, the smarter ones add that if it were possible to recombine all the pollution from a standard automobile, you'd get gasoline and it would be a renewable resource. The catch is that nobody is working to do that. Fission reactors are being worked on all over the world. --Kainaw (talk) 13:22, 2 May 2006 (UTC)
I don't beleive anyone is working on using nuclear waste as a fusion source - fusion power research concentrates on tritium and you would require more energy to reform the uranium than it would produce decaying, so you wouldn't gain any power by the process. And processes already exist to "make" gasoline - they are just not economically advantageous - see Alternative means of producing oil section of Petroleum. Rmhermen 13:45, 2 May 2006 (UTC)
(after edit conflict) Erm, Kainaw...? With all due respect, that's completely wrong. Fusing the products of uranium fission back together to create uranium must take more energy than was gained from the original split of uranium (by the second law of thermodynamics), so you would be using (far) more energy than you produce. The same goes for 'putting back together' all the pollution from an automobile (not to mention the difficulties in collecting it all!). What you are describing is a perpetuum mobile, they do not exist.
Nuclear energy is a definite non-renewable energy source, because once we have used all the uranium on Earth, there isn't any more. It could be argued that coal, oil and gas are ultra-long-term renewables, as they were formed by organic matter compressed at high temperatures for millions of years - so, if we wait long enough (the aforementioned millions of years) the supplies will replenish. But that's only a technicality - we don't have millions of years to wait, and in any case we're using them up hundreds of thousands of times faster than they are produced naturally. So they are effectively non-renewable. — QuantumEleven 13:51, 2 May 2006 (UTC)
If the question had been about "uranium power", I would not stated that it is renewable. However, the question was about "nuclear power". Waste from uranium fission plants is fusable. Therefore, it may be used is a fussion reactor. The waste from the fussion of uranium waste (which I never claimed would be uranium) will most likely be a viable fuel for a fission reaction. This cycle may be repeated until something unusable, such as radioactive carbon, is created. With the technology to rid ourselves of nuclear waste, we will certainly learn to create better reactors and have nuclear fusion/fission of common elements (how about water?). So, "nuclear power" is renewable. But, "uranium power" is not. --Kainaw (talk) 14:49, 2 May 2006 (UTC)
By law of conservation of energy the reverse of a process that releases energy recquires an equal amount of energy. You can only fuse atomes up to iron, and only break them down to iron, so in either way you can only end up with, at best iron. Which is not a viable fuel for any nuclear reactor. Philc T+C 20:50, 2 May 2006 (UTC)
That's not how it works, as far as I understand it. A uranium reactor uses uranium and splits it (fission), releasing energy. The resulting elements are (by definition) lighter than uranium, ie further up the periodic table. If these products are heavier than iron (which most of them are, if I remember my nuclear physics correctly), they may undergo fission again to produce some more energy, although you won't get much out of them - but you can not fuse them together again to produce uranium, because any fusion reaction which produces an element heavier than iron is endothermic. If you get some light elements in your fission waste, yes, these can be fused, but again only up to iron if you want an exothermic reaction - and fusing anything other than the first half a dozen elements in the periodic table is nearly futile, the amount of energy you get out of the reaction is minuscule.
You may have been thinking of nuclear reprocessing, where radioactive waste from nuclear reactors is processed to remove any unfissioned Uranium so it can be used again - but that's a whole different story, for obvious reasons. We have an article on the nuclear fuel cycle which explains everything in far greater detail. Facit: Nuclear power (all varieties) is non-renewable, because the reactions involved to regenerate the fuel used do not occur naturally on Earth (Uranium and other trans-iron elements are only formed in supernovae). So: non-renewable. — QuantumEleven
There is a lot of nuclear reprocessing going on, but that isn't what I was talking about. I was referring to fission of nuclear waste - more commonly referred to as "actinide-burning power plants". Actinide fusion has been done in the small-scale. The large-scale goal is to pair up an actinide fusion plant with each uranium fission plant. Also - please do not continue claiming that I stated "nuclear waste will be fused to make uranium". I never made any such claim. The comment about recombining gasoline is not mine. It should be clear that I was repeating comments from anti-nuclear power people that I do not believe. --Kainaw (talk) 17:21, 2 May 2006 (UTC)
That's still nonsense, sorry. Uranium is an actinide. There's a certain amount of "missing" nuclear binding energy that everything except iron has. This energy is negative, so by converting things to something which is closer (in an approximate sense) to iron, they get more negative energy and you get some energy out. But there's a single chart here; going down it gets you some energy (e.g., fissioning plutonium in a breeder reactor or fusing hydrogen in the sun), and if you like you can spend energy to go back up (which may be fissioning calcium or constructing gold from silver and germanium or so, although the latter may not be practically doable). There is literally no way to make any sort of useful "cycle" on the chart. Perhaps you can reburn the waste from one reaction -- perhaps even in the other direction, if you split big atoms into several small ones -- but it's still a one-way street, and it's entirely nonrenewable (on our time scales). --Tardis 18:51, 2 May 2006 (UTC)
You can believe it is nonsense. Since it isn't working yet, it may very well be nonsense. Just know what you are claiming is nonsense first by going to google and typing in "actinide fusion" to see what I am referring to. It is not fusing some nuclear waste to make some tasty uranium. --Kainaw (talk) 19:34, 2 May 2006 (UTC)
I did that search (without quotes, since with quotes gave results that seemed irrelevant) and saw that the proposal was to use the neutrons generated by power-producing fusion to break apart actinide atoms. This would release a little more energy, although perhaps not as much as building a more efficient reactor that didn't bother with it, and would clean up some nasty radioactive junk that has no other use. Some authors seem to think it could be used to generate plutonium from common 238U, which would be useful for more fission power production. So it's not a bad idea, but it has nothing to do with creating a "loop" of fission and fusion; there are actinides, and there is fusion, but the actinides are undergoing unsurprising fission and the hydrogen is undergoing unsurprising fusion. Hope that helps. --Tardis 22:07, 6 May 2006 (UTC)
I don't believe nuclear is a long run solution because just like petroleum, it's limited. Uranium and other minerals are not unlimited. However, I have to accept that it is a temporary measure and favorable vis-a-vis fossil fuel. Until renewables (minus dams) increase in efficiency and/or become relatively cheap/comparable to other source of energy, nuclear might be of help. There's an article about nuclear power in last April edition of National Geographic with comparison of carbon emission. IIRC in some other article some time ago in Nat'l Geo too, a cost comparison were made between all major source of nuclear, including solar and gangs vs nuclear, coal, crude.
All this however pertains to solving our energy crisis. I don't know about saving the world though. What do you mean by saving the world anyway? __earth (Talk) 13:52, 2 May 2006 (UTC)

Thanks to everyone who responded! I guess I was aware that I wasn't using the Desk as intended, but I couldn't help myself. Opinion-based questions seem to get extremely interesting and intelligent responses here (flattery will get you anywhere). Is there anywhere on Wikipedia where you can hold structured debates? I mean the articles tend to sketch both sides of an argument due to the NPOV policy without letting either side really vent, while Talk Pages tend to get hung up on details. Anyway, thanks again.

While I agree that questions like yours do generate interesting responses, I would have to say that Wikipedia is not the place for debates - it's an encyclopedia, and we try and write the best, most impartial and complete articles we can on a given subject. You could try Usenet, or one of the countless forums debating topical issues (I can't think of any on nuclear power offhand, but there have to be many, many out there).
But it was a fun topic to discuss :) — QuantumEleven 15:24, 2 May 2006 (UTC)
One point - while nuclear is non-renewable, the supply of potentially fissionable materials is pretty large (aside from breeder reactors, there is also the thorium fuel cycle; and thorium is available in massive quantities. Furthermore, increasing the price of uranium wouldn't affect the cost of nuclear power very much (because most of the cost is in building the plant itself). So much lower grade (and thus expensive to mine, but much more abundant) ores can be used; in the longer term even uranium extracted from seawater might become economically viable, and the supply of that is virtually unlimited. --Robert Merkel 15:32, 2 May 2006 (UTC)
Additionally if one factored in the amount of weapons-grade uranium which could be downblended for power production there is already quite a lot of uranium sitting around, out of the ground, with nowhere to go. If one allows reprocessing of plutonium fuel (done in some countries, banned in the US), then one could also get some more bang for the buck. In the end I don't think there will ever be a single technological solution to "save the planet," but ruling nuclear energy out of the possible ways to generate power is just foolish. There are hazards, there are limitations, there are issues, but the same is true with all forms of power generation, and is true in spades with coal and oil. --Fastfission 20:55, 2 May 2006 (UTC)

Evolution-oriented educational software[edit]

I'm wondering if anyone knows of any good software or games that focus on teaching evolution. Currently, the only title I know is SimLife. Anyone have any ideas? Thanks! — Asbestos | Talk (RFC) 16:07, 2 May 2006 (UTC)

  • Richard Dawkins used to have a software program which allowed you to simulate evolution, but I doubt it runs on any modern PCs. This page has some links regarding it and some other similar software, but most of the links are totally dead. SimEarth was another Sim game which had a lot to do with evolution (via ecology). I always thought Oregon Trail had some aspects of natural selection involved in it... --Fastfission 21:04, 2 May 2006 (UTC)
Well, there's E.V.O.: Search for Eden --Chapuisat 21:13, 2 May 2006 (UTC)

How do boats go[edit]

If someone is in a boat in the 1500s & the wind is blowing WEST, how can they go EAST, assuming there is no current?? Obviously they were able to, otherwise one would be at the mercy of the wind when sailing. 199.201.168.100 16:35, 2 May 2006 (UTC)

See sailing (there's a section on sailing upwind). TenOfAllTrades(talk) 16:39, 2 May 2006 (UTC)
Actually, if the wind is blowing straight west, it is impossible to travel straight east by windpower alone. Rather, a boat must keep zig-zagging accross the direction they want to travel in. Also, since you're speaking of the sixteenth century, I assume that you're asking about square rig sails. These do far worse when travelling upwind, although on warships one might see sails in many orientations, to try and sail in any direction. Typically, though, such ships make use of trade winds, which blow predictably, and so can be used to go where you want to go. — Asbestos | Talk (RFC) 17:08, 2 May 2006 (UTC)
The boat just zig zags going north east, then south east, repating this means you go east Philc T+C 21:15, 2 May 2006 (UTC)
I think the term for the zig zag sailing is tacking. --Ginkgo100 01:16, 3 May 2006 (UTC)
Yes, it is called 'tacking'

BigFatDave 12:06, 3 May 2006 (UTC)

Flowchart for the manufacture of DDT[edit]

Hello, I have been trying to get the flowchart for the manufacture of DDT(Dichlorodiphenyltrichloroethane)for sometime now but i've not been successful.Can anyone please help me out.I will be very greatful if anyone can get the diagram for me. Thanks.

Have you looked at our article DDT (which, I admit, does not contain instructions for it's manufacture). Why would you like to make this product? It is available in stores at >90% purity! Andrewjuren(talk) 19:36, 2 May 2006 (UTC)
My organic chemistry textbook (Hart-Craine-Hart, 9th ed.) says it's produced from chlorobenzene and trichloroacetaldehyde with an acid catalyst. No specific reaction conditions are mentioned, but sulphuric acid might make a good solvent. The acid protonates the aldehyde (and the intermediate secondary alcohol), activating it for electrophilic aromatic substitution of the chlorobenzene. Alternately, the reaction might be viewed as SN1 substitution of the activated carbonyl, with the chlorobenzene acting as a (weak) carbon nucleophile.
Consideration of possible alternate reactions suggests that the chlorobenzene, if possible, should probably be supplied in excess. Syntheses of the chlorobenzene and the trichloroacetaldehyde, where not directly available, are left as an exercise for the reader. (Can you tell I just had an org. chem. exam today?) —Ilmari Karonen (talk) 21:05, 9 May 2006 (UTC)

Krebs cycle[edit]

What are the names of the vitamins that play a significant role as coenzymes in the Krebs cycle?

See krebs cycle. (Wow! This is an encyclopedia, not just a message board!) --Kainaw (talk) 17:54, 2 May 2006 (UTC)

Energy[edit]

How many Joules of energy would be procured by a wire 1 metre away from a single iron dipole in a magnetic iron lattice (not counting other atoms in lattice) at 20oC (293.83K)? Thanks *Max* 20:43, 2 May 2006 (UTC).

I bet your textbook has an example that would help. -- SCZenz 21:44, 2 May 2006 (UTC)

This isn't homework! 69.17.182.114 18:32, 3 May 2006 (UTC) (Max)

Half-lifes[edit]

Acording to my Physics book all radioactive substances have a half life during which half of them decay. This means( according to my book) the substance should never decay entirly.

What happens then when 1/2 of the no. of atoms includes a decimal or is smaller than one? For example, 1,000,000,000 atoms with a half-life of 10 seconds. After 100 seconds this should decay to 975,562.5 atoms. Is this posible? If it continues (including Decimals) after 300 seconds (5 mins.) it will become 0.9313 atoms, Again is this Posible? I know an Atom can be broken into smaller particles but can it go like that?

Thanks.

The expected number of decaying particles calculated in this way is an average. Most of the time the actual number of particles to decay will be fairly close to the predicted value from the half-life, but if only a few are expected to decay the actual result will be very different. In the example where the expected value is 0.9313, probably the most likely number of atoms decayed in that time is 1, but in specific cases it may be that 0, 2, or more may decay. The actual number of atoms that have decayed must always be an integer. -- SCZenz 21:24, 2 May 2006 (UTC)
A good analogy to understand this principle is to imagine you have "radioactive coins". These coins are radioactive if they are tails up and not radioactive if they are heads up. So, you start with a bunch of coins that are all tails up. You flip them. About half of them will end up heads up (decayed) and half will land tails up (not decayed). The half-life of your radioactive coins is one flip. Now, on the next turn, you only flip the coins that are still tails up. Again, about half of those will decay. Once you reach a small number, you will realize that not exactly half of the coins will land heads up (especially if there are an odd number of coins) and that the result is entirely probablistic and not deterministic. To learn more, see our articles on Radioactive decay, Radiation, and the Poisson process (which shows the mathematical model of random radioactive decay). Andrewjuren(talk) 21:38, 2 May 2006 (UTC)
This reminds me of the impossibility of having the mythical 2.4 children. Sure, you could chop a kid in half, but that's not really the point. Melchoir 21:43, 2 May 2006 (UTC)
Well, but keep in mind that the number of atoms that have decayed, at a given point in time, is not necessarily well-defined, until you make an observation and collapse the wavefunction. Some atoms may be in a quantum superposition of decayed and non-decayed states. What exactly this means, or in what sense it corresponds to "reality", depends a lot on the interpretation of quantum mechanics. --Trovatore 22:05, 2 May 2006 (UTC)
The statistical interpretation of half-lives does not depend on this kind of argument. It is perfectly possible to measure and record exactly how many decays have occured, and the problem asked above is still valid. -- SCZenz 23:52, 2 May 2006 (UTC)
Well, the statistical interpretation does make the number of decayed particles approximately observable, when there are a lot. It's never exactly observable. Furthermore, the original poster asked about when there was one atom left, a state in which the statistical approximation does not hold, and Trovatore's comment is relevant. -lethe talk + 14:34, 3 May 2006 (UTC)
A famous thought experiment involving radioactive decay and quantum superpositions is Schrödinger's cat. —Ilmari Karonen (talk) 19:49, 9 May 2006 (UTC)

Only in a general sense, that half-life is a bit of a simplifaction. You can't have a partially decayed atom; wither it's one element or another. --Scienda 07:11, 3 May 2006 (UTC)

Chlorine[edit]

I was just wondering who discovered chlorine, and how it was discovered.


                                                                    Signed,
                                                                    Joe
  1. Try learning proper wiki formatting please. It's actually rather simple.
  2. There's a search button for a reason.
  3. Don't waste our time when you could look it up.--Frenchman113 on wheels! 22:06, 2 May 2006 (UTC)
  • uuuh, why is he on wheels?--TiNC 07:49, 3 May 2006 (UTC)

Flight[edit]

Would it be easier or more efficent for a plane to use a anamontronic wing-like aviation s ystem rather than using fixed wings? Would it be more fuel efficent if a giant plane were designed with big wings that moved similar to a giant hawk? And how would I go about getting a patent for this? Lord Westfall 22:32, 2 May 2006 (UTC)

Short answer; no. See Ornithopter. As to your patent question, see patent and prior art, but if you did hypothetically manage to come up with some new way to make an ornithopter's wing's flap, you could patent that. --Robert Merkel 22:42, 2 May 2006 (UTC)

Do those Pills work[edit]

I have a friend who wanted me to ask do those pills that claim to make your cock bigger actually work? My friend asked me, but I don't know what to tell him. So do those pills actually work? If so, which ones? My friend really wants to know. Lord Westfall 22:37, 2 May 2006 (UTC)

Yeah! I'm the one to tell you to look up Penis enlargement. And you have to tell us if you actually paid for those pills on the Internet. --Zeizmic 22:46, 2 May 2006 (UTC)
I was about to post that link. Instead, I will have to content myself with this: your friend, huh? Melchoir 22:48, 2 May 2006 (UTC)
To play counterpart to Melchoir: Why did your friend ask you? Did he suspect that you had needed to use a variety of these in the past? If so, why would he know that? --Tardis 22:51, 2 May 2006 (UTC)
Also read human penis size. The evidence that women actually prefer exceptionally large penises is pretty scanty. And, on the basis you were seriously asking, Melchoir and Tardis are having a bit of a giggle at your expense. Penis enlargement scams are one of the earliest forms of snake oil scam in existence. --Robert Merkel 22:55, 2 May 2006 (UTC)
Well my friend doesnt want to have an exceptionally large penis, he would be happy with 6-7 inches as opposed to the slightly below average size he may currently have. If those pills are a scam, what options does he have? Lord Westfall 23:10, 2 May 2006 (UTC)
You do know that 6-7 inches is about 0.5-1.5 inches over the average, right? You may also want to check out this link. - Mgm|(talk) 09:43, 3 May 2006 (UTC)
Nothing good. All enlargement techniques (various types of surgery, fat injection) result in a loss of penis function. --Serie 00:17, 3 May 2006 (UTC)
The organ between his ears, and how he uses it, will probably make a far greater difference to how enjoyable he and his sexual partner find their lovemaking is than the organ between his legs. Buying a sex manual or learning massage (for instance) would probably be a much better investment (and considerably cheaper)... --Robert Merkel 05:12, 3 May 2006 (UTC)
Note: The "pills to enlarge your penis" are not pills "to enlarge" your penis. That is what the commercials appear to be saying, but if you look at the fine print, they are herbal remedies for erectile dysfunction. You could rationalize that to mean that they enlarge the penis - but not in the way that most people would think. --Kainaw (talk) 12:54, 3 May 2006 (UTC)

Wiki is pretty much anonymous anyway, so no point in the old "my friend was wondering" explanation...we don't know who you are so why bother? Loomis51 01:39, 5 May 2006 (UTC)

Staphylococcal infections[edit]

Staphylococci (including S. aureus and S. epidermidis) are known to migrate along medical devices such as plastic intravenous catheters. However, I believe they lack a flagellum, pilus, or other appendage for movement. Do they migrate along the catheter simply by dividing? Thank you very much.

They cling and they roll: http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1082509Keenan Pepper 00:03, 3 May 2006 (UTC)

Smoking and cancer[edit]

Does anyone know what percentage of smokers actually develop some form of lung/throat/mouth cancer at some point in their lives? I'd be interested in seeing the statisics compared to the same kinds of cancer in non-smokers. I've had a look on the web but it's very difficult to wade through all the pro/anti-smoking propaganda. Anyone have a straight answer? Cheers. --Kurt Shaped Box 23:48, 2 May 2006 (UTC)

80-90% of all lung cancer patients are smokers. I'll try to do a rought estamate of the percentage. If 154,000 (estimated) patients were diagnosed with lung cancer in 2002, and about 85% of them were smokers (let's say), that means about 130,000 smokers worldwide were diagnosed with lung cancer. About 45 million adults just in the US smoked cigarettes in 2004 (I know the years don't match, but this is just an estimate). You should get the idea that a very small percentage (<1%) are actually diagnosed with lung cancer, but that doesn't include other illnesses, and is no excuse to smoke anyway! —Mets501talk 00:22, 3 May 2006 (UTC)
What is the percentage of Emphysema patients who are smokers? User:Zoe|(talk) 01:52, 3 May 2006 (UTC)
According to http://www.stats.org/record.jsp?type=news&ID=555 (not what I'd call authoritative, but the original sources seem somewhat elusive) 1 in 8 smokers ends up with lung cancer compared to less than 1% of non-smokers. These numbers presumably reflect data from the US. -- Rick Block (talk) 02:41, 3 May 2006 (UTC)

I'm not convinced the 154,000 diagnosed is a worldwide figure; it looks more like a country figure. 57.66.51.165 08:00, 3 May 2006 (UTC)

User:Mets501's number is the number diagnosed in a given year. Expand that to the lifetime of a smoker and you get a figure much closer to Rick's 1 in 8. Rmhermen 14:01, 3 May 2006 (UTC)

Thanks guys - I appreciate it... :) --Kurt Shaped Box 00:10, 4 May 2006 (UTC)

Taser noise[edit]

How come stun batons (tasers) make that clicking sound? —Keenan Pepper 23:52, 2 May 2006 (UTC)

Maybe the spark gap switching? [3] EricR 01:41, 3 May 2006 (UTC)

May 3[edit]

diluting acids 2[edit]

i have read over the answers to the previous question regarding this topic and realised that it was a pretty straight forward example and would like to rephrase it to more smaller quantities:

Q: What is the simplest way to dilute 1M Hydrochloric acid down to just 250ml of 0.1M Hydrochloric acid? are there any specific calculations that need to be carried out?

thanks in advance!

A: You need to find out how many moles of HCl you will need to have in 250ml of water in order to have a molarity of 0.1M. Remember, molarity is moles of solute over liters of solution. --Chris 00:48, 3 May 2006 (UTC)
Using
V_{undiluted}C_{undiluted}=V_{diluted}C_{diluted} \
we have
(\mathbf{x} \ L)(1.0 M) = (0.250 L)(0.1 M) \
where
\frac{(0.250 L)(0.1 M)}{(1.0 M)} = \mathbf{x} \ L
and x is liters of 1.0 M aqueous HCl in 0.250 liters of total solution. So your cocktail would be 0.025 L of 1.0 M aqueous HCl in 0.225 L of H2O. Isopropyl 01:34, 3 May 2006 (UTC)

Mystery Fish[edit]

This will probably seem less than mysterious to anyone with a vague knowledge of fish, but unfortunately there are lots and lots and lots and I don't know where to start looking, so... can anyone identify our little friend here so he can find some appropriate articles? Thanks :) Mystery fish (at the bottom) Yummifruitbat 02:24, 3 May 2006 (UTC)

Definitely a marine fish. My guesses would be something related to lionfish or rockfish, although to be quite honest I have no clue. Isopropyl 03:29, 3 May 2006 (UTC)
It's a goby of some sort. I can't name the species; there are quite a lot of them. --Ginkgo100 16:30, 3 May 2006 (UTC)
Thanks, Ginkgo100. I think this was a species from the Pacific coast of North America so I've spent a while googling for a likeness but haven't had much joy. I'll try emailing the aquarium. 'Goby' was right on the tip of my tongue/fingers but I couldn't quite get there and kept thinking of 'Dory' instead... when you replied a little lightbulb went on :)

Which side do you dress?[edit]

How much of the following is true:

A man's penis tends to hang to one side. With this in mind, tailors ask clients "which side do you dress". The majority of men "dress to the left".

I can't find it on Wikipedia, nor on Snopes. If it (or part of it) is true, what factors would influence it?

Thanks! --84.51.154.196 02:31, 3 May 2006 (UTC)

FWIW I've never had this question asked of me when I've purchased suits. Isopropyl 03:28, 3 May 2006 (UTC)
This would presumably be a cultural things. Maybe in some places (I've never heard of any) tailors ask for whatever reason. Maybe in other places tailors might face lawsuits. As for the actual right-left tendancy, if it isn't random then there's bound to be someone, especially on the Internet, who's researched it. Peter Grey 04:24, 3 May 2006 (UTC)
Most tailors cop a feel, or else they can tell very easily while they are down there hungrily studying your junk.

I recently read an article by a doctor, in response to a question from a reader that his penis was oriented towards the left. The doctor had mentioned that most of the men have this feature. He even mentioned that the crotch of the trousers are stitched sligtly to the left side to accomodate this. But I have never had a tailor ask me this neither did I find any left orientation in the ready-made trousers -- Wikicheng 06:14, 3 May 2006 (UTC)

This goes back to the days when men's trousers were a lot closer fitting than they are today. The crutch of the trousers would come right up tight against the scrotum, which needed to be positioned on one side or the other to avoid it being uncomfortably divided, with one testicle hanging left and the other right. It was more a scrotum problem than a penis problem. The penis would obviously go whichever side the scrotum went. Some men preferred the left side, some the right. Tailors would never be so rude as to assume which side the gentleman preferred his dangly bits to hang, but would always ask which side they "dressed". For a tailor's regular customers, this information would be noted the first time, and would be used when making future trousers. I have certainly had this question asked of me. It happens far less these days, mainly because trousers generally have a different shape and the problem is avoided, but also because a lot of guys would consider this a ludicrous invasion of privacy, and no shop wants its staff exposed to charges of inappropriate questions (or even sexual harassment). How times have changed. JackofOz 06:58, 3 May 2006 (UTC)

Strangely, a friend of mine was talkin about this "dress left/dress right" thing the other day, and wondering if it was the exact reverse of handedness (right-handed=dress left and v.v.) Neither of us was keen to conduct a survey, though. Grutness...wha? 07:40, 4 May 2006 (UTC) (r.h./d.l.)
Oh Grutness, you're unbelievably shy when it comes to legitimate scientific research. Live dangerously occasionally.  :--) JackofOz 23:50, 5 May 2006 (UTC)

So is there a WP article about this? There seems to be enough information. It would be interesting.--Sonjaaa 13:34, 6 May 2006 (UTC)

Identifying trees[edit]

What's the easiest way to identify the exact species of various trees I spot in Toronto? Do I need to buy a field guide, and if so which one is best suited for my needs? Do I need to take pictures of the leaves or analyze the bark, or is there some sort of DNA test I need to do to figure out the exact species?--Sonjaaa 02:56, 3 May 2006 (UTC)

A little book, or a field guide is good. I can't think of the one I used when I was in Michigan though... Auto something... or something. He was a bird guy. -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 04:27, 3 May 2006 (UTC)
My old girlfriend used to use "Michigan Trees" by Barnes & Wagner. You're probably thinking of something by the Audubon Society. Isopropyl 07:03, 3 May 2006 (UTC)
Yes, why that is it. the Audubon Society Northeastern tree field guide or somewhat akin. -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 09:24, 3 May 2006 (UTC)


OK i ordered "Trees In Canada" by John Laird Farrar! :)--Sonjaaa 13:00, 3 May 2006 (UTC)

Electrostatics[edit]

Why electric field strength is greater than (force/charge)? thank you. s

Does Electric field help? Melchoir 07:11, 3 May 2006 (UTC)
I thought it was force over charge, although perhaps I am misremembering. — Knowledge Seeker 07:34, 3 May 2006 (UTC)
If you are talking experimental results, maybe you are underestimating force and overestimating charge somewhere. (E.g. your charge is leaking away somehow) --137.205.17.159 11:55, 3 May 2006 (UTC)

Solubility of Ethanol[edit]

I've learned in my Chem class that polar substances dissolve in polar solvents,eg NaOH dissolves in water.Non-polar substances do not dissove in polar solvents and vice-versa.Why does Ethanol(C2H5OH) dissolve in water? This is not a homework question.Just wondering. Thnx

Isn't it because ethanol is polar? Water should dissolve polar substances, in general. The hydroxyl group should make ethanol polar enough to dissolve in water. — Knowledge Seeker 08:13, 3 May 2006 (UTC)
Ethanol molecules form Hydrogen bonds with water.--Ring0 09:25, 3 May 2006 (UTC)
Ethanol is pissed off and wanted to screw everything up for chemistry students. -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 09:25, 3 May 2006 (UTC)
That dangling hydroxyl group has an acidic proton on it. Pretty much any time you see oxygen covalently bound to something, it's going to be a polar bond. Isopropyl 12:45, 3 May 2006 (UTC)
Right, some molecules have polar and non-polar portions of the molecule, Ethanol is one of these. Often it means these will dissolve in either kind of solvent.
Yes in general polar substances dissolve polar and non-polar with non-polar, but the reason why it happens at all is intermolecular forces. There are a few types of these forces, but the ones that are important for these examples are London dispersion forces, dipole-induced dipole forces, and hydrogen bonds. Think of CH_3CH_2OH as two parts, the hydrocarbon part (CH_3CH_2) and the hydroxyl group (-OH). Between water and the hydrocarbon part there are are dipole-induced dipole forces and between water and the hydroxyl group there are hydrogen bonds. The water molecules are bonded together by the same hydrogen bonds while the ethanol molecules are bonded by hydrogen bonds(hydroxyl part) and London forces(hydrocarbon part). Since hygrogen bonds are strong and the hydrogen bonds between the water molecules and the polar (hydroxyl) part of the ethanol molecule have about the same strength the molecules attract each other about the same amount as the forces between two water molecules or two ethanol molecules. As such, they can easily be substituted for each other in bonds (and because of the shape of the molecules there are not many bonds being distrubed by this switch).
As it turns out ethanol is also miscible in hexane (C_6H_{14}). The hexane molecules are bonded together by London forces. Between hexane and ethanol the main forces are London forces between the hydrocarbon parts and dipole-induced dipole forces between the hydrooxyl group and hexane. Together these are about the same strength (in this case) as the H bonds between the ethanol molecules so the bonds are easily interchangable.
London forces generally increase with molar mass and more surface area. As the hydrocarbon chain grows to say hexanol (CH_3(CH_2)_5OH) the London forces play a greater role. Now the forces between the hexanol molecules, largely dominated by London forces over the H bond interactions, is stronger than the H bond between water and the hydroxyl group of hexanol. There is also the issue that the hydrocarbon part of hexanol gets in the way of more H bonds between water molecules. As such, hexanol is not very soluble in water but still miscible in hexane.
If you go the other way and reduce the hydrocarbon chain to methanol (CH_3OH) the opposite occurs. The methanol molecules have the same interactions with themselves, but the London forces are weaker. Thus, the London forces between it and hexane are also weaker and the H bonds between methanol and itself and the London forces between hexane and itself dominate and methanol is not very soluble in hexane. However, it is miscible in water. This is because the London forces between methanol molecules is tiny and the H bonds between methanol and methanol, water and water, and methanol and water are interchangable.
Basically, the greater the forces between two different molecules are in relation to the molecule's forces to itself determine how soluble something is. Generally, two polar substances or two non-polar substances will have greater intermolecular forces between each other than a polar and a non-polar so that is why most solvent-solute pairs are of the same polarity. Kotepho 14:30, 3 May 2006 (UTC)
The short answer is that where solubility is concerned, polarity doesn't have a strict binary yes/no effect. Polarity is a sort of continuum, running from ionic compounds that will dissociate into charged monatomic ions in solution (NaCl forms hydrated Na+ and Cl- in water, for instance) to covalently-bound molecules with a significant dipole moment (methanol or formaldehyde, say) to predominantly nonpolar molecules with some polar groups (long chain alcohols like n-octanol) to completely nonpolar species like carbon tetrachloride or cyclohexane. Solubility will depend on the difference in polarity — as well as a huge pile of other factors that influence the interactions between molecules. TenOfAllTrades(talk) 15:22, 3 May 2006 (UTC)

Fly-by-wire[edit]

Since solar flares are a threat to satellites are they not also a threat to fly-by-wire technology?

Incidentally, I just found a very interesting set of FAQs about aircraft safety here but the guy who runs it has just retired. --Shantavira 08:08, 3 May 2006 (UTC)

Yes. In principle, solar flares are a threat to any and all electronic technology, and plenty of non-fly-by-wire aircraft are more-or-less equally vulnerable to flares (say, when computers regulate the flow of fuel). However, in practice, aircraft fly under the primary protective layers of the atmosphere, so they're far less vulnerable to flares than satellites. — Lomn Talk 13:08, 3 May 2006 (UTC)
Also, most commercial aircraft have triple-redundant primary systems, so even if one computer is knocked out, there are two backups. — QuantumEleven 13:30, 3 May 2006 (UTC)
This is not as comforting as it seems, since, if one computer is knocked out by solar radiation, all three are likely to be. A problem also arose where an escape door blowing off knocked out the hydraulic tail controls, all three redundant systems went through the same place! 165.254.38.126 04:57, 4 May 2006 (UTC)

How do you improve the google rank of a Wikipedia article, e.g. Opus Dei[edit]

Hello fellow Wikipedians! I've been helping edit the article at Wikipedia. I've seen it rise in google rank over time. It is now ranked four, but as you know many Wikipedia articles rank number one. Thus, I also want to know if there are other techniques specific for Wikipedia to improve ranking. FYI, I've done my own search in Wikipedia and read Search engine optimization and other related articles.

Another issue. The pagerank of Wikipedia's Opus Dei article is 6/10 when I use the pagerank at the google toolbar. However, I found out that the Unofficial Homepage which has a google search rank of number two has a page rank of 5/10. This means it has a lower pagerank than Wikipedia's Opus Dei but it is still higher in the google search. Why could it be so?

Looking forward to some great insights on this. Maraming salamat po (thank you in tagalog! Cabanes 09:26, 3 May 2006 (UTC)

  • I think google rank is determined by the amount of people that link to it and the amount of places the article links to. Since spamming the article is out of the question, it might be helpful to ask people with relevant sites to link to Wikipedia. Where a page turns up in the search results not only depends on google rank but also on the meta tags of the site in question and the content of the page itself and the number of visitors. Wikipedia's results placement will improve on its own. - Mgm|(talk) 09:34, 3 May 2006 (UTC)
    • You have things a little backwards, I think. PageRank is determined by what pages link to the article, not the other way around. If the article links to too many pages with low PageRank, though, its own PageRank can be decreased as well (it is a way to penalize link farms). The easiest way to raise the article's PageRank is to link to it from a page which already has a high PageRank. (Easier said than done, but it can be done.) --Fastfission 20:50, 3 May 2006 (UTC)
    • May I ask why Google rank is important to you? Wikipedia is about writing the best possible articles on a subject - the better it is, the more people will link to it, and Google rank will come all by itself. But it's a secondary benefit and not the main reason for writing a good article - I would frown on blatant search engine optimisation at Wikipedia. — QuantumEleven 13:24, 3 May 2006 (UTC)
That's pretty mcuh how I feel. - 131.211.210.12 10:34, 4 May 2006 (UTC)
P.S. Do not try to create a Google rank article, PageRank exists (and is licensed by the guys). --DLL 20:10, 3 May 2006 (UTC)
I created it ;-P --Fastfission 01:12, 4 May 2006 (UTC)
Maraming salamat sa inyong lahat! (that's "thanks to all" in tagalog). Thanks, Fastfission, and congratulations on the article. I suppose when you said it can be done, it means requesting webmasters to put a link on Wikipedia?
Regarding Quantum's question, I completely agree with her/him that it's all about good writing, but I am also interested in countering the black propaganda done by the maker of the Unofficial Homepage who is a communist. I have nothing against him personally, but his ideas are propaganda and propaganda = misleading information. Wikipedia has more balance and more expert, trustworthy information. It would be great if more people get to read it. Thanks for all the help and whatever other help you can give. Salamat! Cabanes 01:53, 4 May 2006 (UTC)
On some level this is out of your hands. At least the official Opus Dei site is number one. But ultimately you're just going to have to trust people's critical thinking and source evaluation skills.
Yeah, I know. --Bth 09:36, 4 May 2006 (UTC)

First human to orbit earth[edit]

Who was the first human to orbit the Earth? Thank You in Advance. --Siddhant 10:36, 3 May 2006 (UTC)

That would be Soviet cosmonaut Yuri Gagarin aboard Vostok 1. --Bth 11:03, 3 May 2006 (UTC)
Indeed, although there are conspiracy theories claiming otherwise - Dammit 11:06, 3 May 2006 (UTC)
Have you ever wondered who makes all these conspiracy theories up, and whether they have some secret reason for doing so? I think that this should be investigated... Grutness...wha? 07:45, 4 May 2006 (UTC)

Of course it would be Gagarin. Sorry I wasted your time by asking such a silly question. Anyway thanks for the answer. --Siddhant 11:24, 3 May 2006 (UTC)

... although it is interesting to note that first non-stop aerial circumnavigation of the the Earth was completed as early as 1949 by the crew of the B-50 Superfortress Lucky Lady II. Gandalf61 12:04, 3 May 2006 (UTC)
Jean Michel Jarre has a song "Hey Gagarin" (Métamorphoses album) about Gararin orbiting Earth, with these cool lyrics: "I can fly, I fly like a sputnik, listen to the music spin, around the planet and lets, dance together".--JLdesAlpins 22:36, 3 May 2006 (UTC)
In any case, in case you're interested, the first true BITCH to orbit the earth would have to be the Russian Laika. But since she's a bona fide BITCH, you may not be interested. I, myself don't consider BITCHES like Laika to be human beings. But that's just me. You may want to call me a misogynist for saying that, but I think you'd be wrong. I may be letting my personal feelings to get in the way of an unbiased analysis, or maybe not. Loomis51 01:46, 5 May 2006 (UTC)

PVC protection[edit]

How can we protect workers who make PVC from the harmful effects of Vinyl chloride?

Replace the humans with robots. --Kainaw (talk) 12:43, 3 May 2006 (UTC)
I'd imagein all the usual methods (fume extraction, respirators, good equipment design, automation etc) can be used to reduce exposure to safe levels. Plugwash 00:48, 4 May 2006 (UTC)

Book about synthesizers[edit]

I've downloaded Chaosynth and its manual provides too little information about the physics of the sound and so. Can anyone recommend me an information source that speaks extensively about the subject? Thank you.

I don't suppose our article on synthesizers has some of the answers you're looking for? Take a look at some of the pages liked from that article, too. — QuantumEleven 13:03, 3 May 2006 (UTC)
How about a website about synthesizers? Sound On Sound magazine ran a very detailed series called Synth Secrets, and it's all up on their website at www.soundonsound.com , however I couldn't seem to find a good index to the series on their site, but there's a great one here: http://www.adp-gmbh.ch/csound/synth_secret.html --Noodhoog 15:55, 4 May 2006 (UTC)

Multiple choice![edit]

Which of the following statements is true?

A. Electrons are negatively charged and are found in the nucleus of an atom.

B. Electrons are negatively charged and are found outside the nucleus.

C. Neutrons are positively charged and are found in the nucleus.

D. Protons are positively charged and are found outside the nucleus.

Please see the top of the page regarding not asking us your homework questions. Your textbook doubtless includes the answers but in case you haven't got it handy our articles on electron, neutron, proton, atomic nucleus and atom should tell you everything you need to know, and much more besides. --Bth 12:58, 3 May 2006 (UTC)
All are true in the right circumstances.
Apart from C, surely? (There you go, anon, a hint!) --Bth 14:09, 3 May 2006 (UTC)
Please read the following:-
1. Electrons revolve around the nucleus.
Some do, some don't. Electrons were thought to all revolve around the nucleus in older models of the atom. See atomic orbital and magnetic quantum number for a current view. (The latter because the magnetic quantum number is related to the electron's angular momentum, and whether it has non-zero angular momentum or not might be one reasonable intepretation of whether an electron "revolves" around the nucleus.)Chuck 17:35, 3 May 2006 (UTC)
2. Protons are positively charged.
3. Positive and negative charges repel each other.
This is just plain wrong. Chuck 17:35, 3 May 2006 (UTC)
4. Electrons are negatively charged.
5. I hope you got your answer.
6. Please do not ask homework questions again.--DIGIwarez 14:29, 3 May 2006 (UTC)
"Positive and negative charges repel each other" - this is a little awkwardly phrased; 'like' charges repel so two positively charged particles (or two negatively charged ones) will repel each other, but a positive particle will be attracted to a negative one. Yummifruitbat 16:06, 3 May 2006 (UTC)
Yes, very true. An exam question that I got a few days ago: "A covalent bond is a shared pair of electrons. Explain how this holds the atoms together." The answer is, of course: The positice nuclei are attracted to the negative electrons; which, overall, results in a neutral atom. This was actually in a prelim and this was a question that was in an actual Credit exam in 2001. Kilo-Lima|(talk) 18:57, 3 May 2006 (UTC)
I'm not sure what you mean by the above - a covalent bond results in a molecule with the two atoms sharing electrons in order to achieve full outer electron shells. This is not really relevant to the original question and I fear you may have misunderstood the exam question :( Yummifruitbat 22:21, 3 May 2006 (UTC)
I am extremely sorry. Positive and negative charges attract each other. Like charges repel each other. I am really sorry. The correct answer would be B. You are right Chuck. That was a small mistake I didn't notice it. Electrons in an atom always revolve around the nucleus. I think this question is about a simple atom not a covalent compound. Elctrons can be found freely but this is not about charge or radioactivity. It is a simple question on the structure of an atom. Negative charges can also be found inside the nucleus (β particles). But that is not important over here.--DIGIwarez 07:24, 4 May 2006 (UTC)
A negatively-charged beta particle is an electron. And D can also be true -- protons can be found outside the nucleus in many high-energy situations (though I suppose it can always be argued that they're hydrogen ions, though in such cases that's not a helpful way to look at them). The only one that's 100% always false is C, becauses neutrons simply aren't positively charged. --Bth 07:43, 4 May 2006 (UTC)
True, but the person who asked this question was probably not looking for all this. I think this is about the basic structure of an atom. We are making this too complicated.--DIGIwarez 07:53, 4 May 2006 (UTC)
Oh yeah, this is obviously a middle school level question with an obvious correct answer (not obvious enough that the questioner could get it, mind). However, you can't ask such a question to a bunch of people with more advanced knowledge without expecting them to caveat the hell out of it -- it's human nature. --Bth 09:33, 4 May 2006 (UTC)
As sad as it may seem, this could easily be from an american university general chemistry class--64.12.116.74 19:16, 4 May 2006 (UTC)
Can a proton be outside a nucleus, I don't think so as a proton defines a nuclei. A proton on its own with no electrons or neutrons, is not just a proton it is a hydrogen nuclei. So only A and B are possible. Philc T+C 21:43, 4 May 2006 (UTC)

RoHS Directive[edit]

In the Restriction of Hazardous Substances Directive page (2002/95/EC), paragraph 4 under "Details" states the maximum concentration of Hexavalent Chromium by weight of a homogeneous material is 0.1%. Where is that stated in the Directive? Thank you.

Is that an English Comprehension homework question? And isn't the answer to the question contained within the first sentence? --Shantavira 16:13, 3 May 2006 (UTC)
That limit is not specified in the RoHS directive itself, it is in Commission decision 2005/618/EC, which ammends the annex to the RoHS directive to allow up to 0.1% by weight of the subtances covered by RoHS except cadmium which it limits to 0.01%. -- AJR | Talk 16:22, 3 May 2006 (UTC)

The Sims 2[edit]

How exactly do you get the helicopter to pick you up in The Sims 2, when you need to get to work? Thanks, Kilo-Lima|(talk) 18:48, 3 May 2006 (UTC)

Have you tried a game hint site like GameFAQs.com? You should be able to find the answer (and a lot more besides!) there. — QuantumEleven 07:51, 4 May 2006 (UTC)

brain size in dogs[edit]

do st bernards and chihuahuas have the same size brain since they are the same species? Or does brain size relate to the size of the dog? thanks

carol

Your guess ? --DLL 19:55, 3 May 2006 (UTC)
Generally body mass correlates with brain size (see brain to body mass ratio). Brain size does not correlate to "species" necessarily, especially with there is high variability in body size within a species (such as with dogs). --Fastfission 01:10, 4 May 2006 (UTC)

gas mantles (non radio active gas mantles)[edit]

does any body know what are the latest coleman non radio active gas mantles made of and what would be the appropriate composition and formula for making a durable ,strong ,bright white light gas mantle(non radi active ) and has there been further develoment in this particular area and by whom.

Wow, this attached encyclopia-thing always fails to amaze me! I typed in 'gas mantle' and I found out that your little Coleman is radioactive! but probably as much as smoking one ciggie. The problem is with mantle factories handling truckloads of thorium. Apparently, the substitutes don't work as well. --Zeizmic 20:18, 3 May 2006 (UTC)
Indeed; I'd be more worried about the health effects of the combustion byproducts generated while the lamp is still warming up—sooty things like polycyclic aromatic hydrocarbons, which are known carcinogens. (If you've been exposed to smoke from you campfire or barbecue, too, then you might as well give up now.) The exposure to radiation from the lamp mantle is negligible unless you're eating the darned things. TenOfAllTrades(talk) 20:37, 3 May 2006 (UTC)
Colman made mantles are nowadays made of yttrium, not thorium although other companies still make the thorium ones. [4] Rmhermen 00:52, 4 May 2006 (UTC)
Apparently they also contain a small amount of cerium [5] Rmhermen 00:55, 4 May 2006 (UTC)

Sequential times[edit]

Why no article on sequential times? 01:02:03 on 04/05/06, [6]?

Sequential times is now a redirect to sequential time. --Kainaw (talk) 19:59, 3 May 2006 (UTC)
Koolio! Thanx! I used the search, but nothing came up...
It also looks like some idiot is trying to delete the small article that there is - is there anything I can do to stop that?
He'll stop, don't worry. Monitor the article, and warn the jerk. -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 20:55, 3 May 2006 (UTC)
For the record, prods do not constitute jerky behavior. Melchoir 00:53, 4 May 2006 (UTC)
Stupid* ones do. 165.254.38.126 04:52, 4 May 2006 (UTC)
  • Where the 'proder' doesn't bother to research the article.

Computer science[edit]

WP offers a search bar with two buttons, Go and Search.

Firefox offers search engines but the WP one only ... searches. Does anyone know about a "Go" engine ? Thanks a lot. --DLL 20:06, 3 May 2006 (UTC)

When looking for seach bar options, pick "Wikipedia (en) - Instant" -Obli (Talk)? 20:31, 3 May 2006 (UTC)
Thanks! I never used the stupid search bar because it always went to a search result list. It was quicker to bookmark Wikipedia and use the page's search box. --Kainaw (talk) 23:14, 3 May 2006 (UTC)
Thanks, that's what I needed. --DLL 20:57, 4 May 2006 (UTC)

Warren Truss[edit]

hey i need information on the Warren Truss bridge design, thnk you, matt

I assume you mean truss bridge and not the Australian politician? Isopropyl 22:49, 3 May 2006 (UTC)

Bloody eye[edit]

This is NOT the place for medical consulting, I know that, but this is of no importance, and not exactly a thing I'm gonna see a doc about. I just noticed that on my right eye, there was a bit of pink discolouration. So I look closer in the mirror, and it looks like some veins that have blown or something. Nothing big, just a tiny bit of pink (no intense red) that's not noticable for anyone not looking closely, focusing on it. What could this be? More importantly, what could it be caused by? Although it's hard to describe it, I can clearly see that there are some veins there, so it's not some sort of spot that's flooded with blood. Thanks in advance! 213.161.189.107 22:24, 3 May 2006 (UTC) Henning.

There are blood vessels in the eye, and they can burst. Pressure, shock, randomness etc can cause this, and in moderate amounts it's normal and will disapear pretty quickly. See someone if it persists for more than a few days. 165.254.38.126 22:46, 3 May 2006 (UTC)
Sounds fine to me. If it hurts get help. -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 06:03, 4 May 2006 (UTC)

May 4[edit]

Illogical (to me, at least) gull behaviour...[edit]

I like to feed the gulls (herring gulls, lesser and greater black-backs around here). I get together a big pile of scraps and leave it out in the garden for them and watch them feeding through the window.

Invariably, as soon as one of the flock of gulls I've attracted descends and picks up a piece of food, the rest of them immediately get angry and give chase to that single bird across the sky in an attempt to rob it of its meal - completely ignoring the fact that there is about 2lbs of meat/cheese/bread/etc. just sitting there on the ground.

Why are gulls seemingly more intent on expending time and energy to deprive another gull of food when by simply cooperating and putting aside their squabbles for five minutes, they would all be able to gather round and eat plentifully from the pile? This doesn't make sense to me at all (actually, it seems like a very human mindset). :)

Quite often, while the rest of the gulls are flapping, bickering and screeching in the sky above, a single bird will land at the food and quietly and calmly eat its fill then leave before the others have given up the fighting and noticed. Thus, the 'jealous' majority miss out. Do you think that this is a sign that this particular gull is more intelligent than the rest?

As someone else, somewhere online once put it - a gull's mindset seems to be "Everything that's mine is mine. Everything that isn't mine is also mine". :)

--Kurt Shaped Box 00:38, 4 May 2006 (UTC)

Have you seen Finding Nemo? :-) Yummifruitbat 01:32, 4 May 2006 (UTC)
Heh. Yes I have - the characterization of the gulls was spot on, wasn't it? :) --Kurt Shaped Box 01:40, 4 May 2006 (UTC)

Three thoughts:

1) Perhaps having "excess food" is so out of their normal experience that they don't know a different behaviour would be beneficial in such cases. That is, they are going strictly by instinct, which developed based on food being scarce.

2) The fighting over food may also be a way of establishing dominance, which may also come into play during mating.

3) They might want to avoid landing for fear of predators, like dogs.

StuRat 01:56, 4 May 2006 (UTC)

Just wanted to remind ya'll that feeding the birds is generally discouraged if you wish to keep droppings off your aerially exposed surfaces. Isopropyl 04:02, 4 May 2006 (UTC)
Nah, just catch 'em, cork 'em, then let 'em go. :-) StuRat 17:57, 4 May 2006 (UTC)

Foreskin redux[edit]

This was asked further up the page a few days ago but no-one replied. Is a 'normal' foreskin supposed to retract fully behind the head of the penis when it's erect? Thanks. --84.71.80.239 00:44, 4 May 2006 (UTC)

When mine is pulled back the most it can go comfortably, mine doesn't go behind the head. It only reveals a little bit of it, but even then, just barely. But really, your question is too ambiguous. What does "normal" and "head" mean? Not that I'm an expert, but everyone's body is different. If I were you, I'd try not be overly concerned about what is "normal", and focus more on what's comfortable for you. --69.156.159.59 01:06, 4 May 2006 (UTC)
"Head" is pretty standard, and means the lumpy bit on the end that generally doesn't become really prominent (if I remember right) until somewhere during puberty. I hope it doesn't need to be pulled back much, since mine hardly does at all. No matter what state it's in, it always covers the entire head, with of course an opening of varying size, and pulling it back farther than that feels rather like pushing back my cuticle or giving blood: not pleasant, in a weirdly uncomfortable way. I can't imagine this ever causing me problems, and in fact I was amazed to find out it can work any other way short of circumcision. A word of advice, based on the conversation above: don't mess with it until it's actually a problem, and consider finding a second opinion. Doctors have been known, like everyone else, to talk out of their asses at times. Black Carrot 01:16, 4 May 2006 (UTC)
In the foreskin article, doesn't it say that "[a study] found that about 50% of young men had full coverage of the glans, [and] 42% had partial coverage"? Black Carrot 01:25, 4 May 2006 (UTC)
Have you read phimosis? I think it's only likely to be considered a problem if it can't be retracted fully even when flaccid,and even then opinions are divided about whether there are any serious implications. Yummifruitbat 01:30, 4 May 2006 (UTC)

Digg.com[edit]

Is [7] generally reliable? More specifically, what are your takes on [8] and [9]? Black Carrot 01:16, 4 May 2006 (UTC)

Digg is essentially just a collection of links to other sites, plus comments. The sites linked tend to be reasonably mainstream, though, rather than some sort of crackpot link collection. I would take essentially anonymous one-line comments on a website with a grain of salt. (Oh the irony!) As far as scitech goes, I'd put the collective intelligence of Slashdot ahead of Digg. The two stories you've linked seem like the classic "idea papers". Someone comes up with a novel idea, and the physics that might theoretically work; they write a paper because it's more fun than real research, the university promotes it because it's easier to get public attention than real research, and BBC prints it because it's cooler and more interesting than real research. So yes, they're theoretically correct. But moving from theory to practice may well be impossible. How long have there been blueprints for a space elevator, for instance? --ByeByeBaby 01:48, 4 May 2006 (UTC)
You'll like Digg. Kilo-Lima|(talk) 18:14, 4 May 2006 (UTC)

== Do birds masturbate? == bbbbbbbbbbbbbbbbbbbb


This is not an attempt at vandalism, so pls don't revert my question. :)

My (male) macaw likes to rub his butt area against his toys and perches and seems to get really excited when he does this. He goes faster and faster, hooking his tail under whatever he's humping before he stops and sits there panting with his feathers fluffed up. It looks to me like he's getting himself off and cumming. Is he? Do birds really masturbate? Should I try to stop him doing it?

I doubt you could stop him. Males of most species are remarkably persistent this way. :D
Console yourself with the thought that while your macaw is an onanist, unlike some birds he at least isn't a homosexual necrophiliac rapist: [10]. TenOfAllTrades(talk) 01:55, 4 May 2006 (UTC)
Dorothy Parker named her pet budgie Onan because he "spilled his seed". JackofOz 02:36, 4 May 2006 (UTC)
Sounds like the poor guy could do with some female company. If you don't want to buy a lady macaw perhaps a date could be arranged.--Shantavira 08:45, 4 May 2006 (UTC)
Raising parrot chicks is a major commitment and very time-consuming. Attempting to breed the bird without lots of knowledge and preparation is probably not a good idea. In other words, he should practice planned parrothood. --Ginkgo100 19:53, 5 May 2006 (UTC)

He probably is masturbating. Birds have no concept of 'sinful' or 'inappropriate' behaviour. It's a natural bodily function - I'd just let him get on with it. If you try and stop him (some bird owners squirt their pet in the face with cold water from a plant mister when they catch them wanking), he'll just get cranky and aggressive from the hormone buildup. --Kurt Shaped Box 17:54, 4 May 2006 (UTC)

Just to be sure here, it's not just male birds that are apt to that sort of behaviour. I once had a female parakeet who, on several occasions, would rather disturbingly raise her tail and develop a rather scary look on her face whenever I'd take her out of her cage. Needless to say it wasn't long before she laid an (unfertilized) egg. This happened several times. I actually tried to get her a male companion but she was so territorial that after a couple of weeks I found the male dead at the bottom of the cage. A clear case of ornicide. Oh well, at least I tried. Loomis51 01:31, 5 May 2006 (UTC)

Kiwi Birds[edit]

My daughter needs a source to interview for a report on kiwi birds. Any ideas of where to obtain a speciallized individual on kiwi birds? Dg2 02:54, 4 May 2006 (UTC) Thanks dg2

Try a university zoology department or a zoo. --Ginkgo100 03:27, 4 May 2006 (UTC)
If you can conduct the interview comfortably by email, then I'd suggest contacting the New Zealand Department of Conservation or the Kiwi Recovery Programme. There are more experts on kiwi there than anywhere else on earth. Grutness...wha? 07:53, 4 May 2006 (UTC)

Summer or Spring[edit]

Is it Summer or Spring when the North Pole is tilted toward the sun. -- Jesusfreak 03:47, 4 May 2006 (UTC)

The North Pole tilts furthest towards the sun at the June solstice. This occurs on June 21/22, early summer in the Northern hemisphere. -- Avenue 03:46, 4 May 2006 (UTC)

Thank you very much. -- Jesusfreak 03:47, 4 May 2006 (UTC)

In fact, the June solstice is the first day of summer. Consequently, the North Pole is tilted towards the sun (to varying degree) for the entirety of both Spring and Summer (and for none of Winter and Autumn), and the tilt is split evenly between the two. — Lomn Talk 13:26, 4 May 2006 (UTC)
Of course that's only in the northern hemisphere. Don't forget the Aussies! (And others like South Americans) For them, June 21/22 is the winter solstice. (You can thank me later, Jack!) Loomis51 02:21, 7 May 2006 (UTC)

Nitrogen[edit]

What color is a nitrogen flame?

Nitrogen is inert, and does not burn. -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 04:29, 4 May 2006 (UTC)
Nitrogen's atomic spectrum looks kind of golden yellow. [11] hyperphysics with pretty pictures of elements in spectral tubes. NOTE: spectral tubes are not flames, however both methods look at excited electrons. Nitrogen can't burn but we can shoot electrons at it and get the same results. Sifaka talk 04:58, 4 May 2006 (UTC)
Doesn't nitrogen "burn" during a lightning strike? (Though the colour of lightning isn't the colour of burning nitrogen.) --Bth 09:06, 4 May 2006 (UTC)
A quick look at nitric oxide supports that lightning indeed produces at least one of the nitrogen oxide compounds. (Here is where I go wildly speculative as my chemistry knowledge is zero:) Perhaps all reactions that produce nitrogen oxides are endothermic and thus not really burning which is defined as an exothermic reaction? Weregerbil 12:28, 4 May 2006 (UTC)
Reaction energy depends on entropy, which depends on temperature. A reaction which is endothermic at one temperature can be exothermic at another. For instance O2 + 1/2 N2 --> NO2 is endothermic at room temperature but exothermic at temperatures above ~190 C. --BluePlatypus 15:40, 4 May 2006 (UTC)
Mac Davis: Nitrogen does indeed burn at sufficient temperature, forming nitrogen oxides. NOx production is an environmental problem with any sufficently hot combustion using air as an oxidant. It's why we've got catalytic converters on cars. --BluePlatypus 15:31, 4 May 2006 (UTC)
Louise: Lightning occurs due to the ionisation of nigrogen, oxygen and other constituents in the atmosphere at the time, like an arc generated during welding.

Why does burning hair smell bad?[edit]

Hair has a lot of disulfide bonds (cystine I assume), and I assume it is liberated in the form of malodorous molecules, but is there a primary molecule or class of molecule (more specific than sulfides) that causes the stench? Sifaka talk 05:12, 4 May 2006 (UTC)

In my (extremely limited) experience, shoeing horses and cauterising wounds produces the same unpleasant smell. That suggests there's nothing specific to hair.Notinasnaid 09:22, 4 May 2006 (UTC)
That's because the same class of proteins - the keratins make up hair and epidermis. Someone else wrote already that they are rich in cysteine, a sulfur-containing aminoacid. Sulfur compounds smell bad, as a rule. Dr Zak 11:50, 4 May 2006 (UTC)
Why do we consider burning certain proteins a bad sensation ? 1) If it is our kin, there is a conservation thought, 2) if it is food (or foe), that indicates too much cooking. --DLL 21:03, 4 May 2006 (UTC)
All creatures find the smell burning creatures (particularly their own) disturbing, much in the same way that we don't like dead bodies, it has benefitted the human race through evolution to be scared of death, and generally burning human is closely associated with death. Philc T+C 21:31, 4 May 2006 (UTC)
Also, in general, gaseous sulfur compounds are poisonous in high concentrations, so it make sense that low concentrations stink: it encourages you to leave before you get killed. --Serie 21:34, 4 May 2006 (UTC)

Zero Gravity[edit]

Is it possible to achieve zero gravity on earth?

If by "zero gravity" you mean weightlessness, then yes: just go into freefall. Ways of acheiving this include being in an out-of-control lift (not recommended because of the crash landing at the other end), the early part of a parachute jump or flying a plane in a parabolic arc (see Vomit Comet, a name applied to any of several planes used for astronaut training -- one was also used for the weightless scenes in Apollo 13). Deep-sea diving provides a similar experience to weightlessness, because of the support provided by the water, and indeed much astronaut training takes place in huge tanks. --Bth 07:28, 4 May 2006 (UTC)
When you jump into the air and then fall back down, for about one second you're in zero-gravity. Try holding something like a ball in a cup (or a glass of water, if you don't mind getting wet) while you fall down. The ball will float inside the cup and it's really cool! Jonathan talk 17:20, 4 May 2006 (UTC)
If you were in zero gravity, you would not fall back down when you jumped, so your are in gravity, and if you are on earth that is 1G of gravity, you are however weightless, i.e. if you jump out of a plane and stand on some scales as you fall, you will register zero (discounting effects of air resistance). Philc T+C 15:40, 7 May 2006 (UTC)
Zero gravity can only be acheived outside the universe, or debatably at the centre of mass of the universe. Philc T+C 21:32, 4 May 2006 (UTC)

Continuing from Jonathan, even when you jump off from a small height (say from the top of a table or a small ladder (basically when you are experiencing a free fall), you are in zero gravity -- Wikicheng 23:57, 4 May 2006 (UTC)

Trampolines (especially the really big ones at the local gym) are brilliant for this kind of experiment - from the moment you take off to the moment you land, you are (barring a small component of air resistance) weightless. Although you may want to ask before doing Jonathan W's experiments... :) — QuantumEleven 06:55, 5 May 2006 (UTC)

Airplane Safety[edit]

Can diesel be used in a high compression ratio jet engine so as to enhance safety in case of a crash as diesel does not catch fire due to sparks and spillage?

What do you think they use as jet fuel? --Zeizmic 11:42, 4 May 2006 (UTC)
Diesel engines for airplanes exist, do check our article on aircraft engines and most especially aircraft diesel engines. In short, diesels do very well at running at medium power for extended times (operating consditions in aircraft); what prevents wide adoption is the small market combined with the extended certification process. Dr Zak 11:56, 4 May 2006 (UTC)
I believe a variant of Kerosene is used as jet fuel, because it does not burn as vigorously as gasoline.

Physics Question[edit]

According to the formula e=mc², it is possible to get a lot of energy from a very small amount of mass. Practically, we lose of a lot of energy in every machine. If we burn a lot of coal, a huge amount of it is wasted as ashes. Even in nuclear power plants, a lot of radioactive material is wasted as nuclear waste. Is there any(practical/theoretical)way to convert the whole of a substance into energy without wasting much?

Matter-antimatter reactions are pretty much the only candidate for total conversion of rest mass, though even that ends up with a substantial amount of the energy going into neutrinos. Very much a theoretical option, and even an arbitrarily advanced society would have trouble making antimatter without expending a vast amount of energy.
There is the possibility of collecting small amounts of antimatter (but enormous compared to what we can currently produce) in the magnetic fields of various bodies in the solar system. See [this Nasa Institute of Advanced Concepts study. However, the cost and complexity of such collection mean it's unlikely to be used as a domestic power supply; it'll almost certainly be used only where energy density is really important like spacecraft propulsion. --Robert Merkel 02:03, 5 May 2006 (UTC)
This is, famously, how the Starship Enterprise is supposed to achieve the power required to go faster than light. --Bth 08:59, 4 May 2006 (UTC)
In nuclear power plants, there is probably not as much waste as you think. Its a lot heavier, but by volume it is pretty small. (
Comparison of medium sized nuclear power plant's fuel consumption to a man, ~6 ft. tall.
Matter-antimatter reactions annihilate totally, releasing heat and light, with no waste matter (there is still waste, but only in energy form). It still takes a lot to generate that antimatter though. Nuclear fusion is probably the best way to go in the next few hundred years, supplemented by solar panels, if they are cheap and efficient enough. -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 09:05, 4 May 2006 (UTC)
I think the questioner is seeing all matter left over as possibly-energy-by-E=mc2 and thus views both ashes and nuclear waste as huge amounts of rest mass just sitting there going to waste.
In general, combustion releases energy from chemical bonds, which is absolutely tiny compared to rest mass (less than a millionth of one per cent), and both nuclear fission and fusion release nuclear binding energy, which is on the order of 0.1%. --Bth 09:19, 4 May 2006 (UTC)
I know about the small amount of enrgy which is released through combustion and also the nuclear binding energy which is released in fission and fusion reactions. I just wanted to know whether the total annihilation of matter and the subsequent release of energy is possible or not. The examples that I used in my question were probably not correct.
Thank you very much, but what about cold fusion? Is it really possible to make small scale fusion batteries?
See cold fusion. Short answer: no. --Bth 09:21, 4 May 2006 (UTC)

Copolymerization[edit]

How can polymerization be used to make PVC soft without using plasticers? Thanks in advance.

While this is just an educated guess (my schooling in polymers was limited) I'd say that using 2 different monomers with different spacial properties to polymerize randomly, you would end up with strains with random spacial properties, that are unable to neatly fit next to each other. And i do believe that the degree of order in a polymer is a strongly related to it's hardness. I've always seen it as the difference between the different in a bundle of Pick-up sticks lying neatly together, or it being a jumble. And this forces a jumble by bending sticks in different random places. SanderJK 10:37, 4 May 2006 (UTC)
Well, it depends on where you're starting from. If you've already got the PVC, there's not much that can be done by polymerisation (other than melting and mixing with another, softer, polymer) to make it softer. However, if you provide enough heat to raise the sample above its glass transition temperature, it'll become soft and flexible. If you're starting with the monomers, you can control the degree of polymerisation by a number of means, and this'll affect the physical properties of the polymer produced, including rigidity. Generally, the lower the molecular weight distribution, the softer the polymer. Unfortunately, Polyvinyl chloride is produced via an addition reaction rather than a condensation reaction, so I can't point you to the Carother's equation, but by adding another chemical capable of reacting with the vinyl chloride into the mixture, the average chain length should be decreased, and the polymer made softer. GeeJo (t)(c) • 21:17, 4 May 2006 (UTC)

Anything you add to the PVC could be construed as a plasticezer because you are taking away from the purity of the end product. The best way to do this is to create a plastic that is more amorphous (non-crystaline) which will make the plastic more of a tangled mess of molecules thrown together in a ball rather than an ordered crystal which is much more rigid. The best way to do this is to heat the plastic past its melting point until it is in a near liquid form with a lowered viscocity. Mix it well then super cool it. This will shorten the chains as you have broken some of the intermolecular forces of the original plastic and it will take away from the crystalinity. However once you do this it will severely degrade the plastic.

True. Also, since the reaction forming PVC is based on a fre-radical chain, it's highly susceptible to temperature. So to add to my previous statement, provided you're starting with the vinyl chloride monomers, altering the reaction temperature (and keeping it regulated since the reaction is exothermic) is also a viable method of changing physical properties of the polymer. GeeJo (t)(c) • 23:51, 5 May 2006 (UTC)

Converting pdf file to editable format[edit]

Hello, Is it possible to convert a pdf file (Adobe Reader 6.0) to a text format that I can edit. As it is currently Acrobat won't let me select anything to copy & paste it, when I try to save as text it saves a blank txt file & when I try to copy the file to the clipboard & paste it it doesn't paste anything. AllanHainey 09:47, 4 May 2006 (UTC)

If a PDF file is not protected and contains text, Adobe Reader will let you copy/paste the text into other applications. From this we can conclude that the PDF file you have does not contain text. It's most likely scanned pages, big pictures with no text at all. The only solution would be OCR (available in commercial Acrobat and other tools). Notinasnaid 09:53, 4 May 2006 (UTC)
A pdf file can be protected so that you are not allowed to select from it even though it is not password protected. So it is still text format and not a picture, but acrobate reader refuses to let you select from it. It is possible to convert a file like this to text using a pdf to text converter IF it ignores the select lock flag. Open source and freeware software is most likely to do so. Good luck. Stefan 10:15, 4 May 2006 (UTC)
This is indeed a possibility, but in such a case Reader would also refuse to save text. Since it allows you to save text, but saves nothing, I have to conclude there is no text. Notinasnaid 11:05, 4 May 2006 (UTC)

You can use a software called PDF to Word v1.6 to convert PDF files into RTF format. RTF files can be edited normally with a text editing software(MS word for example). This software is not free. You can get it at http://www.verypdf.com/pdf2word/index.html. This is not an advertisement, you can use any other software if you like.--DIGIwarez 10:06, 4 May 2006 (UTC)

But does this software do OCR? I can't see any mention of this on its web page. Without OCR, it's likely to produce a word file with a picture of a scanned page. Just like the picture in Reader, not editable text. Notinasnaid 10:06, 4 May 2006 (UTC)
No this is not an OCR. It works on a normal non-scanned PDF file. Please try it if you have any doubts. It's free for a limited amount of files. You should be able to edit the text portion quite easily.--DIGIwarez 10:27, 4 May 2006 (UTC)
So I think we have to assume that it won't help the original questioner? Since if it was a normal non-scanned PDF, they would have been able to copy/paste or save text? Notinasnaid 10:33, 4 May 2006 (UTC)
The questioner asked for a software with which he could convert a PDF file into a text file. The above software can do that. If it fails then an OCR software might be necessary.--DIGIwarez 10:41, 4 May 2006 (UTC)
Thanks, it looks like the pdf document is just scaned pages so I'll look into OCR, anyone know a good free OCR software? AllanHainey 12:12, 4 May 2006 (UTC)
GOCR is opensource and free. I've never used it however (I know the site because it was recommended to me once before on this very page). — Asbestos | Talk (RFC) 15:47, 4 May 2006 (UTC)
OCR is often pretty bad with PDFs. You'll probably do better to just print it out and then re-type it -- because you will probably have to go over and check every single word for OCR errors anyway. OCR is useful for searching documents, but it is not very good for replicating their exact text, in my experience with Adobe Acrobat's OCR functionality. --Fastfission 16:11, 4 May 2006 (UTC)

Hi, what you need is a software that can read image from pdf and save as text. Here is one OCR software Image to OCR Converter It converts image-only, searchable pdf and copy restricted pdf to text-only pdf. There are many ocr software available like the one GOCR mentioned above, but these OCR generally create searchable pdf but not a text-only pdf. I assume that you understand the difference between an image-only pdf, searchable pdf and text-only pdf. Please read: http://products.softsolutionslimited.com/img2ocr/help.htm#pdf_types here the questioner is asking for a pdf format that can be converted to any text based format or can allow copy paste of characters which in this case is only possible if he knows the password of pdf or if he converts it to a text-only pdf. Only text-only pdf can be converted to text based formats like word, doc, html etc. while searchable pdf and image-only pdf will only give you images. Searchable pdf lies somewhere in-between image-only and text-only pdf. So you can use text-only pdf of this software to use it as you like. Let me know if there is any other software that can convert image-only pdf to text-only pdf and not to searchable pdf which is of no use when performing copy/paste or pdf format conversion. I have used almost all available ocr and pdf to doc converters and this problem is quite frequent. Also, in regard to the solution posted by DIGIwarez, every pdf to word, doc converter may not be an ocr / text recognition software. You have to read spec of software or use the software to find it. Here idea is to convert images to text and as well as preserve to layout / text structure of pdf.

Radioactivity[edit]

If β-particles are negatively charged, how can they stay inside the nucleus?

They don't. They're emitted at high speed. But they start in the nucleus, hence all the hairsplitting in the previous question. (And note that being negatively charged shouldn't prevent them staying in the nucleus at all, as negative and positive charges attract one another; it's the high energy from their being created in a nucleon's decay that means they shoot off. What should surprise you is that the protons in the nucleus don't all repel each other, which is down to the strong nuclear force.) --Bth 10:07, 4 May 2006 (UTC)
By negatively charged particle I meant electron. I could not understand how electrons were produced inside a nucleus. Thanks for the answer
They are produced by means of beta decay: one neutron transforms into one proton, one electron and one anti-neutrino.--Ring0 15:21, 4 May 2006 (UTC)
Think of E=mc^2. Energy and mass, are kind of the same thing down at the particle physics level. -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 10:56, 4 May 2006 (UTC)
Yes, but how is it related to the question?

I think what you are trying to ask is how protons can stay in the nucleus together despite their mutual electrical repulsion due to their positive charges. The answer is that the nuclear force is a stronger attraction than their electrical repulsion, at that distance. StuRat 18:17, 4 May 2006 (UTC)

dieting[edit]

i recently heard that dieting DOES NOT reduce the amount of body fat.Then why do people recommend & follow it?

I suspect someone has played a prank on you (or is trying to sell you a snake oil dieting product of some sort). See dieting, in particular the section How the body gets rid of fat. 12:33, 4 May 2006 (UTC)
I'd say it depends on what the diet is. A diet of Big Macs and Cokes probably wont reduce the amount of body fat. GeeJo (t)(c) • 20:58, 4 May 2006 (UTC)
I have seen someone lose weight with this kind of diet (Actually, it was Big Macs and beer). After three months of it, he had lost something like 20 pounds. If you can successfully force yourself to only eat one, it probably wouldn't be long before you get sick of it. - user:rasd

See http://home.howstuffworks.com/diet.htm for an excellent article on dieting --Wikicheng 00:12, 5 May 2006 (UTC)

milk[edit]

why does sugar mix well in hot milk than cold milk?

thanks!

Milk is mostly water. If you've ever tried to make lemonade or Kool-Aid before, you know that it is easier to mix the sugar in water if you use hot water and then refridgerate it. Of course, that takes a long time, so you have to suffer through that first warm glass with some ice cubes. --Kainaw (talk) 13:35, 4 May 2006 (UTC)
It takes energy to break apart the sugar molecules making up the crystals. By heating the milk, you increase the average temperature of the sugar/milk mixture farther above the activation energy of the solvation reaction, and so make it easier for the sugar to dissolve. GeeJo (t)(c) • 20:57, 4 May 2006 (UTC)
The saturation point increases with temperature. Isopropyl 22:42, 4 May 2006 (UTC)

Simple Answer: Milk is made of molecules that whizz around, bumping into each other. Sugar is also made up of molecules, but they are 'holding on' to each other, making them solid instead of liquid like the milk. When a milk molecule hits a sugar molecule, if it's going fast enough and strongly enough it will break the sugar molecule off the lump of sugar and dissolve it in the milk. The warmer the milk is, the faster the milk molecules whizz, and the harder they hit the sugar molecules. Also, as they are moving faster, they hit the sugar molecules more often. This means they break sugar molecules off more often, dissolving the little lumps of sugar faster. Skittle 16:01, 5 May 2006 (UTC)

Disposal of nuclear waste/material[edit]

Hi again, a U.K. committee set up by the government to look into the best ways to dispose of nuclear waste/materials recently reported the best way would be to bury it deep underground. That got me thinking - what would happen to it if we got it into magma, like a volcano, but instead of just tipping it in Mt Etna we dug down & put it into a deep underground magma flow? Would it burn up, at least partially, solidify underground in the rock, shoot right back up & create a radioactive volcano where we dug or just turn the lava radioactive creating radioactive rocks/volcano lava sometime in the future? Also would it be possible to do this given the pressure/temperatures involved? AllanHainey 12:47, 4 May 2006 (UTC)

It can be "burned" in the correct circumstances. In a recent question, I referenced a process called "actinide fusion" - but the articles about it were too technical for me to read. Thanks to Philc for explaining it laymen's terms, I can now say that actinide fusion is, for the most part, burning up nuclear waste in a fusion reactor - rendering it harmless (non-radioactive). --Kainaw (talk) 13:30, 4 May 2006 (UTC)
There is, of course, no burning involved in "actinide fusion" - at least as that word is conventionally used and as the questioner appeared to use it. Dropping nuclear waste into magma will not change the waste into a non-radioactive substance. Rmhermen 16:37, 4 May 2006 (UTC)
Burning in this sense is used in a sort of slang physics way to mean a reaction that recquires activation energy, but then subsequently releases more energy, it also hot. This is an incorrent use of the term, however it is widely understood, and therefore regularly used. Philc T+C 18:17, 4 May 2006 (UTC)
I have heard it suggested the nuclear waste be reacted with silicates to make rock then dropped into a subduction zone. I have not read anything about the feasibility of this though.
At all of the places that we have access to the mantel, there is a high probability that it will come back up again relatively soon, for example hotspots, plate boundaries and volcanoes, these are likley to either spew magma onto the surrounding land, or leave it in rock form in the crust. So chucking radioactive waste, simply antognises the situation with already threatning magma now with radioactive waste. Philc T+C 18:17, 4 May 2006 (UTC)
  • The best way to dispose of nuclear waste is to bury it. (People seem to think that's bad because it's the same thing people have been saying for 40 years. But it's the other way around - It's still the best option after 40 years of heavy research in the field.) Anyway, to answer the question: You don't want to put it into a geologically active area because then it can escape. And the whole point of end-storage is that you don't want the radioactive materials to be dispersed. If we did, we might as well blow them out a smokestack. Also, nuclear waste is for the most part already solid. --BluePlatypus 15:23, 4 May 2006 (UTC)
    • As a caveate, one should bury it, but where and how to best bury it are still very contentious scientific and political debates. As for the waste itself, it depends on what sort of waste you are talking about. Reactor waste is solid but wastes generated by processing plants are often liquid. --Fastfission 16:15, 4 May 2006 (UTC)
It is dangerous to think that we can dispose of nuclear waste that will still be active thousands years after. In rich countries, you can pay for safety but you get a police state ; in poor countries, risks are greater and may come back to you if you go on feeding terrorism.
Cooking waste in clean nuclear plants is also risky, as costs are heavy, economic return uncertain, technology and security still immature. We use costly power (nuclear, oil) without seeing the true price. --DLL 21:13, 4 May 2006 (UTC)
Which is why a minor world war was fought on Talk:Nuclear power... ;-) — QuantumEleven 06:51, 5 May 2006 (UTC)
Note, however, that the Oklo reactor lasted intermittently on this planet for about 150,000 years, and now, 2 billion yars later, the waste from it has traveled remarkably little distance, despite geological fractures and the seepage of groundwater. (All this without, needless to say, any effort at all by human beings.) -Wiccan Quagga 07:27, 7 May 2006 (UTC)
Oklo may have lasted that long all that time ago, but the high intensity low half-life stuff is long gone now. What we make has to stay where we put it, and doing that properly means correct estimates of a larger number of quite disparate things: climate and hydrology of hte site, tectonic and hot spot activity at the site over say 100000 years, and so on. Otherwise, we might as well do what the Soviets are said to have done with quite a few submarine power plants, to wit, dumped 'em in the sea in the Arctic. 71.249.12.89 06:05, 11 May 2006 (UTC)

Heat Absorption from Light[edit]

Why does a black car absorb more heat than a white car when it becomes exposed to sunlight?Patchouli 14:08, 4 May 2006 (UTC)

Did you have the science class on visible light? (not everyone does, since science is considered a sin in many places) White things reflect all visible light. Black things absorb all visible light. Red things absorb all but red light. Blue things absorb all but blue light. The more light absorbed, the more heat the object will absorb. Now, if you want to get very technical, it is possible to reflect ultraviolet and infrared light while absorbing all visible light and avoid so much of the heating effect, but who'd waste their time doing that to a car? --Kainaw (talk) 15:06, 4 May 2006 (UTC)
Note that absorbing visible light warms a body up in exactly the same way as absorbing infrared or ultraviolet -- it's a common misconception to think that visible light doesn't warm up objects. All waves in the electromagnetic spectrum carry radiant energy, and absorbing this (which a black surface will do faster than a white surface) will warm an object up. Note also not to mix up cause and effect: It's not that an object reflects light because it is white, it is white because it reflects light. — Asbestos | Talk (RFC) 15:30, 4 May 2006 (UTC)

So we see the reflected color, and thus for a black object no light is reflected. Also, we don't see IR and UV light because they don't get reflected.Patchouli 17:45, 4 May 2006 (UTC)

We don't see IR and UV because our eyes can't detect them. Some other animals can see them, however. StuRat 18:06, 4 May 2006 (UTC)

Bees for instance can see the ultraviolet patterns on many flowers; you and I can not. -- Scienda 18:40, 4 May 2006 (UTC)

Keep in mind that "seeing" is only one sense. We "feel" infrared in large quantities as heat. Perhaps that is why our eyes never felt the need to see it. Also, I've read many articles that talk about a rather recent evolutionary jump that allowed humans to see blue. Before that, texts would describe grey skies and green oceans. Maybe we'll continue further along to ultraviolet. --Kainaw (talk) 18:53, 4 May 2006 (UTC)
I seem to recall that in an episode of QI, Stephen Fry brought up the fact that the ancient Greeks had no word for blue, instead calling it bronze. I very much doubt that an evolutionary jump could have affected every living person since the conception of the written word however, given the date of the most recent common ancestors ( GeeJo (t)(c) • 20:53, 4 May 2006 (UTC)
I remember it from many stories. One I found interesting was a period where the king wore blue because most people saw it as greenish-gray, not blue. It was assumed that the upper class could see it as blue and it was used as a test. Of course, everyone claimed they could see it as blue even if the king purposely came out in a gray robe. Then, that article argued that this may have been the origin of the "king with no clothes" story. As for the evolutionary jump, it wasn't as much of a jump as it was a progression. To this day, blue-green blindness is common (though clearly a minority). It isn't really the inability to tell blue from green. It is an inability to see blue, so it looks green. --Kainaw (talk) 00:37, 5 May 2006 (UTC)
Maybe this is how blue blood came about to describe aristocrats.Patchouli 11:04, 5 May 2006 (UTC)


I'm sorry, but this is nonsense. 1) We don't feel infrared any more or less than we feel any other kind of radiation (IR not heat, read the darn articles). 2) Evolution has nothing to do with "feeling the need" to see different wavelengths. We just evolved to be receptive to one sub-set of wavelengths, birds and some other animals to other. 3) The idea that we had an evolutionary jump a few hundred years ago to see colors is rididculous, though having or not having a word for a color is a different matter.
See "Heat Transfer Mechanisms" in the heat article. Infrared is used to transfer heat and the human body senses infrared (and visible light) as heat. See evolution. An "evolutionary jump" doesn't happen overnight. It happens over many generations. Humans have been through many evolutionary jumps: gaining opposable thumbs, hips that allow us to walk upright, larger brains... Being able to see blue is an evolutionary jump that we are just getting to the end of. There are still many people who cannot see blue. It is nonsense to claim that people named every shade of every color on Earth with the exception of blue. --Kainaw (talk) 19:53, 6 May 2006 (UTC)
I must agree with Kainaw in some aspects; while of course we can perceive infrared as heat we perceive other electromagnetic radiation similarly. Eyes cannot feel a need to develop abilities, nor does evolution work like that. There would be many difficulties with an infrared-sensitive retina; ones that come to mind offhand are the infrared emitted by our own bodies (including our eyes), and the infrared-opaque nature of some components of our eyes. In addition, I must express strong skepticism regarding the proposed recent evolution of the ability to see blue; what precisely is meant by "an evolutionary jump that we are just getting to the end of"? Even if the ablility to see blue is a new mutation, it cannot affect an entire species in this manner; it will only affect its descendants. If this mutation truly arose after recorded history, then only the descendants of that person would have this ability. For example, if it began in Europe in modern times, for instance, then no African, Asians, or any others should possess this ability. In fact, the ability to see blue is quite old; most primates have two pigments, one for a bluish color and one for green/yellow, that diverged from each other some 500 million years ago. The cone commonly called "red" developed more recently, but was in a primate ancestor, not in humans. [12] has some information on this. — Knowledge Seeker 20:24, 6 May 2006 (UTC)
Plus, you can see a colour without naming it; Think of 'Robin red-breast' with its orange front. Seems like people just called orange things red in Britain until the orange was introduced. Skittle 15:33, 7 May 2006 (UTC)
IR is related to black body radiation, in that bodies at room tempuarture emit IR radiation. Therefore, IR camaras can be used to see people in the dark, and this is often referred to as "heat sensing" cameras. This then confuses people into thinking IR is heat, which is mistaken. Also, as KS shows above, it is impossible for any mutation in recorded history to have affected everyone on the planet, as not everyone on the planet can trace their history back to a single ancestor living in recorded history. edited by me to remove unecessary rudenessAsbestos | Talk (RFC) 02:30, 8 May 2006 (UTC)
Nobody except you claimed any confusion about IR and heat. Where is your proof that humans do not have nerve cells that are excited by infrared light? That is the claim that was made. You just failed to read it in your eagerness to flame someone. Where is your proof that humans do not have a gene on chromosome 7 that was the last mutation involving human eyesight's ability to sense electromagnetic radiation? Nobody except you claimed it was a mutation that took place a few generations ago. I said that I read research papers that claimed it was still common for people to be unable to see blue in the earliest recorded history (about 5,000 years ago). But, you apparently failed to read it in your eagerness to flame someone. --Kainaw (talk) 02:52, 8 May 2006 (UTC)
I'm really sorry for the post above, as I mentioned on your talk page. I'm confused as to why we're on evolution, but in answer to your questions: people don't usually ask for negative proofs. You don't ask a scientist "where's your proof that we don't have nerve cells that sense [IR light/gamma rays/dark matter]", or "where is your proof that humans do not have a gene on chromosome 7 that affects [eye sight/ultra sonic hearing/etc]". Normally people expect positive proofs: e.g. a paper that shows we have a nerve cell that is affected by whatever it is. The fact that we sense heat by thermoception is undisputed, but no one is suggesting we have IR-sensing cells. Anyway, I'm really interested in the paper you read about not sensing blue. Do you have a citation I could look up? (PubMed finds nothing). I'm confused because, as KS mentioned, we know pretty much when the blue cone cell developed (c. 500 million years ago), but I wrote my undergraduate thesis in part on whether naming colors affects the perception of colors, so it's a topic I'm interested it. — Asbestos | Talk (RFC) 11:45, 8 May 2006 (UTC)
I replied on my talk page. What you said is correct. I have been plagued recently with accusations that I've said things that I haven't said. I was mainly just saying that our perception of the electromagnetic spectrum is not limited to our eyes, just as sound isn't limited to your ears when there is plenty of bass to rumble the floor. As for evolution, that is so long ago that is like another life. I really only remember the story I related. The rest of my memory is faulty. I know red/green evolved first in primates. I don't know if it is all primates, including monkeys and everything, or just the greater apes. Then, blue developed in early human ancestors. The research I as assisting (mainly by reading articles and highlighting parts the docs wanted) was in looking for a genetic cure for blue-green blindness. Since I can read Chinese, I would come in and have a stack of Chinese research papers on my desk. (Note to everyone: When someone says they can read Chinese, that means that they know the 300-500 common characters used in a Chinese newspaper or magazine, not the extra 1,000 scientific characters that are never used in common Chinese! I spent most of time with a Chinese dictionary.) I can tell you that the ability to see blue is on chromosome 7. A 'defect' in at least one gene (there was a dispute about some others) causes an inability to see blue. Then, I got off that stupid project and worked on one that used computers to detect if a song is "pleasing" or "not pleasing". I know, third-hand knowledge of a topic is rather useless, but that's all I had. --Kainaw (talk) 15:25, 8 May 2006 (UTC)

The speed of light vs. theory of relativity[edit]

Einstein says that it's impossible to go at the speed of light, because the closer you get to the speed of light, you become heavier, time goes slower, and you get flatter.

But Einstein also said that speed is relative. You can't measure your speed unless you compare it to something else. When you're going 100 km/hr on the highway, what's really happening is your car is moving 100 km/kr relative to the Earth. When you calculate that the Earth is moving 1500 km/hr when it rotates, what's really happening is the Earth is rotating 1500 km/hr relative to the Sun.

So how can you say that you're approaching the speed of light if speed is relative? Jonathan talk 15:20, 4 May 2006 (UTC)

The speed of light isn't relative. It is the same for all observers (see Michelson–Morley experiment). So, even if you had flied in a very fast spaceship, the light speed still would have been for you 300 000 km/s.--Ring0 15:49, 4 May 2006 (UTC)
The trick is that it's not that you are approaching the speed of light with respect to your own measurments of the speed of light -- your measurments of the speed of light never change, as you say. Rather, it's only using a third reference point that one can say that you're traveling at 90% speed of light. — Asbestos | Talk (RFC) 17:27, 4 May 2006 (UTC)
Yes, that's exactly what special relativity is about, solving that apparent

contradiction. – b_jonas 12:21, 6 May 2006 (UTC)

"Going the speed of light" doesn't have any physical meaning, just as dividing by zero has no mathematical meaning. Asking "I know you can't go the speed of light, but what would happen if you did?" is like asking "What would happen if you could cut a pizza into exactly zero slices?"

-User: Nightvid(unregistered)

Well, obviously light goes at the speed of light, but that's allowed (in fact required) because it's massless. I can cut a pizza into zero slices if there's no pizza to begin with! Melchoir 08:09, 8 May 2006 (UTC)

Oh, I get it now! Thanks. Jonathan talk 14:47, 8 May 2006 (UTC)

Mechanical collision[edit]

Give an example of a mechanical collision in which energy gets dissipated even in ideal circumstances, that is, where energy dissipation is unavoidable due to the law of conservation of momentum. —Masatran 15:26, 4 May 2006 (UTC)

Consider inelastic collision of, say, two plasticine balls. --Ring0 15:54, 4 May 2006 (UTC)
I am looking for an elastic collision. —Masatran 17:00, 4 May 2006 (UTC)
That can't happen in an elastic collision, so there aren't any examples. Conservation of momentum always holds. Conservation of kinetic energy does not. --HappyCamper 17:21, 4 May 2006 (UTC)
To User:HappyCamper: I think you mis-read my question. —Masatran 17:31, 4 May 2006 (UTC)
An elastic collision, by definition, conserves kinetic energy. Any collision where energy is converted to other forms is inelastic. TenOfAllTrades(talk) 17:36, 4 May 2006 (UTC)
There are two equations that together govern all collisions between two objects:
m_1 * v_1 + m_2 * v_2 = m_1 * v_3 + m_2 * v_4 (Conservation of momentum)
m_1 * v_1^2 + m_2 * v_2^2 = m_1 * v_3^2 + m_2 * v_4^2 + E(Conservation of energy)
For any collision, once you know all but two of the parameters (typically the two final velocities are unknown), you can determine everything else. What you seem to be looking for is a collision where the conservation of momentum formula forces "E" (the energy lost to inelasticity) in the conservation of energy formula to be non-zero. --Serie 22:04, 4 May 2006 (UTC)
I don't know an exact example, but I think the key is that the collision shouldn't be central (or head-on), that is, that the two bodies can't collide in an elastic way because then the force would have to act on a point where the two bodies don't touch. – b_jonas 12:15, 6 May 2006 (UTC)
Nothing in the law of momentum conservation prevents a collision from being elastic, regardless of whether the collision is head-on or not. A collision may be inelastic for other reasons, but not because of momentum conservation. Arbitrary username 17:43, 6 May 2006 (UTC)

Aluminum fluoride[edit]

Isn't the molecular formula for the ionic compound aluminium fluoride Al3+(F-)3? I done it in chemistry today and it apparently was correct. However, according to the PubChem article, [13], it is simply AlF3. Which is correct, mine or theirs? Thanks, Kilo-Lima|(talk) 16:45, 4 May 2006 (UTC)

These two formulas both reflect the fact that aluminium fluoride molecule consists of one aluminium atom and three fluorine atoms. The first formula shows additionally ions' charges. --Ring0 16:59, 4 May 2006 (UTC)
So, which one should really be included in the article? Kilo-Lima|(talk) 17:04, 4 May 2006 (UTC)
I would keep AlF3 and not use the ionic representation. The latter is implicit in the former if one knows that AlF3 is an ionic compound. But of course, an explanation in the article always helps. --HappyCamper 17:19, 4 May 2006 (UTC)
There is not normally any need to show the charges on the ions, as the compound AlF3 can only be formed from those ions. Most likely, the reason your chemistry teacher has asked you to show the charges is to illustrate that you understand what is happening. Yummifruitbat 17:24, 4 May 2006 (UTC)
  • The compound is only usually given as AlF3. Al3+ indicates that it is a free ion, which would usually mean that it is in solution. You do not write the redox state of ions in a compound, only for free ions. When you do need to give the redox state, it's done for the metal ion and in parenthesis. E.g. "Iron (II) oxide" is FeO and "Iron (III) oxide" is Fe2O3 --BluePlatypus 20:44, 4 May 2006 (UTC)
Also, the bonding is to some degree covalent in every molecule, so using Al3+(F-)3 as a formula would be using an idealised approximation. GeeJo (t)(c) • 20:48, 4 May 2006 (UTC)
In fact, based on what I can find on the web, it seems AlF3 is more covalent than ionic, existing in its solid form as a polymer or network covalent macromolecule with three-center two-electron bonds. One simply does not normally get a 3+ charge on a single atom as would be required if AlF3 were mainly ionic. —Ilmari Karonen (talk) 22:34, 4 May 2006 (UTC)

Microscopic organism that looks like a tube[edit]

What is the name of the microscopic organism that looks like a tube, and moves by bending forward, placing its head(?) down, and bringing its feet(?) up; that is, it is upside-down(?) at every alternate step? —Masatran 18:00, 4 May 2006 (UTC)

You mean an organism than moves by rolling? Other than the tumbleweed I can't think of any offhand. But then, I'm not a biologist. GeeJo (t)(c) • 20:45, 4 May 2006 (UTC)
I think he means it moves like a slinky. Black Carrot 00:19, 5 May 2006 (UTC)

Kinda like this?

 ___/    _____   _______   _____    \____
/       /                       \        \

A physics teacher told me about it. I don't know what it is, but it works because of the order the segments move in. If you thought about it in terms of physics without considering the solution it is in, it would seem like the creature would get nowhere, however it works becuase the fluid at this scale is very viscous. Whenever it makes a stroke, it either has the other segment streamline or out. When it makes a forward stroke, the other segment is stream line, whenever it makes a backward stroke, the other segment is down and provides drag which limits the amount of backwards motion. Looking at the picture above, it starts in the s shape. The stroke with the front segment pushes the creature backward a little, but the other segment is down limiting its backward motion. The next stroke pushes it forward, and since the creature is streamlined compred to where it was in the first position it has moved a little ahead. And no I don't know what it is called. I wish I could help more... Sifaka talk 04:18, 5 May 2006 (UTC)

It's called a hydra. --Heron 20:35, 6 May 2006 (UTC)
Those aren't the only small invertebrates to move that way - Temnocephalids do (we don't seem to have an article on them, but they're a type of flatworm, and part of class Turbellaria). Grutness...wha? 07:49, 8 May 2006 (UTC)

Headphones[edit]

I have three places for my headphones to plug into the computer: one on my DVD drive, CD drive and another near the bottom of the computer, where a bit of the computer "lifts up" and there are USB ports there, too. The only place I can plug the headphones into and hear sound is from the one in the bottom. When I plug it into the DVD or CD part, near the drive, no sound comes out of the headphones. Why is this? And can I route it to the CD drive? Thanks, Kilo-Lima|(talk) 18:38, 4 May 2006 (UTC)

The connection at the bottom is connected to your soundcard, while the ones on your DVD/CD drives are internal to the drives. Those two will only work when you're playing an audio cd in the respective drives, because that does not require processing by the soundcard. To answer your second question; I don't think it's possible to route the signal back to the drive. - Dammit 19:06, 4 May 2006 (UTC)

Contact in sports[edit]

Which is more likely scientifically? Making contact with a Roger Federer serve or a Roger Clemmons pitch?

Those situations are so different that the only scientific way to compare them is by experiment; that is, gathering historical statistics. Melchoir 19:18, 4 May 2006 (UTC)
The serve. Baseball pitches are contacted, generally speaking, about half the time. Federer does not generally have half his points via aces. — Lomn Talk 19:57, 4 May 2006 (UTC)
Depends on what matches you go to often. – b_jonas 12:01, 6 May 2006 (UTC)

Women more suceptible to cold?[edit]

I've frequently heard that women are, in general, more suceptible to cold than men. (That is, to feeling cold, not to freezing to death.) Is this true? If so, what are the reasons for it. Thanks. -- SCZenz 19:02, 4 May 2006 (UTC)

I have heard the opposite. Women have a layer of fat just under the skin which provides limited insulation.
Men have a layer of fat under the skin, too. Without it, every vein would be visible, as they are on some feet, which have very little fat.
Indeed they do, but women seem to feel the cold a lot more strongly than men, at least if the complaints by my mother and previous two girlfriends that "It's bloody freezing in here!" when the thermostat reads a fairly warm 24C have been anything to go by. I suppose it could be psychological, or have something to do with bad circulation or more sensitive skin, or it could just be that they feel more free to complain, while us macho men suffer in silence. Or it could be none of the above, and have a fairly simple explanation that I've not thought of. GeeJo (t)(c) • 20:32, 4 May 2006 (UTC)
This is because women are whiners...
Put in a less technical sense, that is probably what it is. Although women produce more morphine in their body than men, they still have lower paint tolerances than men; men have a more machismo idea, that you're more manly if you can go through more pain. Women, have no such idea that they have to prove themselves like this. -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 21:13, 4 May 2006 (UTC)
I'm not sure that this is related to the production of morphine by the body. That generally only affects pain reception in the short term (minutes). Whereas after I spent a whole afternoon fairly comfortable in a T-shirt in a room heated to 24C, my last girlfriend walked in in a sleeved blouse and immediately said "Christ it's cold in here! Why don't you turn the heat up?" I'd say it's more likely to be a skin issue than an internal one. GeeJo (t)(c) • 21:24, 4 May 2006 (UTC)
Responders to questions like this seem disturbingly eager to chalk apparent gender differences up to female inferiority! In my experience (no more scientific than the other anecdotes people are posting), most men whine more if it's too hot than women do. Although menopause in women switches it around. --Ginkgo100 20:07, 5 May 2006 (UTC)

I believe this is a simple surface area to volume ratio effect. That is, smaller objects lose their heat more rapidly than large objects. Women are typically smaller than men. Children and babies are even more susceptible to the cold, although their higher metabolic rate may compensate to some degrees. StuRat 23:29, 4 May 2006 (UTC)

I cant explain it, but my (male) hands are always warm, whereas girls hands i touch/hold are nearly always cold. am I alone in thinking this? --Ballchef 23:50, 4 May 2006 (UTC)

Nope you aren't alone. My hands are always cold. I agree with the surface to volume ratio idea and would also like to posit that muscle mass has something to do with it too. I have noticed the trend people with more muscle mass don't feel as cold as often. Men typically have greater muscle mass than women do Sifaka talk 04:03, 5 May 2006 (UTC)
Women react to temperature stress by concentrating heat in their core body mass more so than men. This adaptation is believed to exist to help protect the uterus (and any associated pregnancy) from the effects of cold; however, it means that everything else being equal a woman's extremities will tend to get colder than a man's. I also agree that surface area to volume effects probably play a role as well. Dragons flight 11:03, 5 May 2006 (UTC)
Which has the side-effect of making women better at making pastry, according to my cookery teacher. Cooler hands mean the fat doesn't melt as much when you're 'rubbing' the flour in. Skittle 16:10, 5 May 2006 (UTC)

Limiting blood flow to the extremities to preserve core body heat is not unique to women, men do this, too. However, if women are more often cold, due to their higher surface area to volume ratio, then this protection mechanism will be activated more often in them. Note that this shows they really are colder, it's not just a psychosomatic issue. StuRat 16:27, 5 May 2006 (UTC)

Another factor may be fat distribution. Slim men tend to have a rather even distribution of fat, while thin women tend to have fat concentrations in their breasts and butt. And, of course, evenly distributed fat provides for better thermal insulation. StuRat 16:34, 5 May 2006 (UTC)

I think it might also be that when a woman feels cold, it's more likely that he will complain about it or turn the thermostat higher, while a man – even though he feels cold the same way – is more likely to ignore that and just continue work or whatever he's doing. (Or am I thinking too much in a hacker way?) – b_jonas 11:59, 6 May 2006 (UTC)
I seem to remember that females have lower metabolic settings than men, by and large, and that will lead to colder extremities. The cube-square law difference seems to me to be too small to account for the observed behavior. And of course some of that observed bahavior is likely due to attention seekin, look at me! drama to which some females are prone, while the male equivalent is suually more about acting out in some way. Whatever, it's been my experience that they all have cold feet and hands. Most of the time. And all this despite the higher body fat percentage. 71.249.12.89 06:20, 11 May 2006 (UTC)

Boiling point or vapor pressure?[edit]

Which is more correct 'Distillation is a method of separation of substances based on differences in their boiling points.' or ' Distillation is a method of separation of substances based on differences in their vapor pressures.' -- Dbroadwell 19:52, 4 May 2006 (UTC)

Offhand, and as a non-expert, I'd say they're both roughly correct, but the difference in vapor pressure is a bit more precise. In my understanding, what matters most is the difference in vapor pressures at the operating temperature of one's apparatus ; but realistically speaking, one probably designs an apparatus to take into account the entire phase diagrams of the substances. Melchoir 20:10, 4 May 2006 (UTC)
Both are just as correct, because vapor pressure and boiling point are not independent properties. Another way of saying it is that the seperation is due to the differences in Activity coefficient. (lousy article, though) --BluePlatypus 20:35, 4 May 2006 (UTC)
Perfect. -- Dbroadwell 22:27, 4 May 2006 (UTC)
And if both are equally correct, we should use the simpler explanation, which is the difference in boiling points. That will make it easiest to understand by the widest possible audience. StuRat 23:21, 4 May 2006 (UTC)
Vapor pressure increases with temperature according to a standard formula (see Clausius-Clapeyron equation). The boiling point is the temperature at which vapor pressure equals the ambient pressure (because this is when you can get bubbles of gas forming within the liquid rather than just evaporation from the surface). A substance with a larger vapor pressure at a given temperature will also have a lower boiling point. Arbitrary username 14:54, 6 May 2006 (UTC)

Braking rocket vs. retrorocket[edit]

I've made a bunch of redlinks to braking rocket; there's already an article on retrorockets. I tend to gather that a "braking rocket" is fired during reentry and landing to oppose gravity and slow the fall, while a "retrorocket" is fired in orbit to lose angular momentum and allow a landing in the first place.

Is this accurate? Is there really a distinction in terminology and/or design between the two purposes, or am I just confused? Melchoir 20:24, 4 May 2006 (UTC)

Well, the term "retrorocket" generally refers to any rocket that provides thrust in the direction opposite to motion. I think "braking rocket" is just a less widely used synonym. — TheKMantalk 21:35, 4 May 2006 (UTC)
According to the last paragraph of Retrorocket, "[r]etrorockets are also used in landing spacecraft on other astronomical bodies, such as the Moon and Mars". This, admittedly brief, description matches the usage I'm familiar with, and Google seems to concur. I've therefore taken the liberty of turning your redlink into a redirect. —Ilmari Karonen (talk) 21:39, 4 May 2006 (UTC)

I see. Thanks! Melchoir 00:41, 5 May 2006 (UTC)

Aaargh! My eyes![edit]

Howdy! Why is it that immediately after coming indoors after spending some time in bright sunlight, everything appears to have a fairly strong green tint to it, that disappears after 30-60 seconds? Is there a fairly humdrum reason, or could it be something to do with the multiple ophthalmic surgeries I had as a child to correct fairly strong strabismus (two on the right, one on the left)? GeeJo (t)(c) • 20:25, 4 May 2006 (UTC)

I have no idea, but I don't know if it's green tint. I spent an entire day outside in the sun only, with lots of snow, and returned to my once so very familiar school building to find myself completely amazed at how different the colours were. Highly, highly freakish. So, might not have anything to do with such an operation.
It's because of the ability of the human eye/brain to compensate for light sources with different white points: clear-sky sunlight has a color temperature of around 5000K-6000K, while incandescent light bulbs have a color temperature around 2800K (a very "reddish" white), and fluorescent lights have a white point that's completely off the color temperature scale (typically, a bluish white). However, despite the differences in the light put out by these light sources, a white sheet of paper will still look white. That's your brain compensating. You're seeing green when you come indoors because the brain doesn't adjust instantly. --Serie 22:17, 4 May 2006 (UTC)

Another thought, are you wearing greenish tinted sunglasses when outside ? If so, those would block the green light and make everything appear less green. When you remove them, everything would then appear more green by comparison, until you got used to it. StuRat 23:15, 4 May 2006 (UTC)

That would be reddish-tinted glasses. Greenish-tinted glasses would make everything look more green by blocking red, and when you took them off everything would look more red. —Keenan Pepper 23:30, 4 May 2006 (UTC)
Well, if they reflect all green light, they would look green to others but reddish when looking through them. StuRat 16:38, 5 May 2006 (UTC)
I guess that's possible, but it would be really weird. I don't think I've ever seen a material quite like that. If you put it down on a table it would look green, but if you held it up to the light, so that the light was behind it, it would look red. —Keenan Pepper 01:09, 6 May 2006 (UTC)
Well, I have seen reflective sunglasses that look silver to others but like regular sunglasses when you look through them. StuRat 18:47, 6 May 2006 (UTC)
Keenan, you'd be interested in dichroic filter. kmccoy (talk) 05:01, 11 May 2006 (UTC)
The green-tint thing happens to me too. I always thought everything looked darker inside because your brain was trying to shift from lots of light outside to less light inside. Jonathan talk 01:59, 5 May 2006 (UTC)

It's not your brain that adjusts, it's the cells in your retina. --Username132 (talk) 20:14, 5 May 2006 (UTC)

Geejo, I'm going to tack a rider onto your question, because I have a question about tinting as well. Speaking of glass tint (someone brought it up! someone brought it up!), y'know that strip of blue...uh...stuff?...that's at the top of most windshields? What is that for? What's it called? It doesn't seem to do anything for glare...the windshield article doesn't mention it at all. Cernen Xanthine Katrena 14:12, 7 May 2006 (UTC)

It's supposed to prevent you from being blinded by the sunlight at dawn and dusk and getting in an accident. Putting the sun visor down, wearing sunglasses, and avoiding driving toward the sun at those times of day are far more effective, however. I haven't seen that blue strip as much on recent cars. StuRat 18:11, 9 May 2006 (UTC)

Name that bird[edit]

Outside my window in Charleston, SC, I see hawks circling a lot. They are rather large. The weird thing is that they are often chased and pecked at (in mid-air) by tiny black birds. The tiny black birds will pester the large hawks for a very long time. It makes no sense to me because the hawk is more than large enough to kill the tiny black birds with a single swipe of a talon. So, I wonder what kind of birds these little things are and why the hawks deal with them so patiently. Anyone have a guess? --Kainaw (talk) 20:26, 4 May 2006 (UTC)

  • could they be baby hawks?--64.12.116.74 21:18, 4 May 2006 (UTC)
Says this site "I see crows and other birds periodically chasing the hawks around our place." --DLL 21:32, 4 May 2006 (UTC)
The hawk is large enough to kill the smaller birds, but not fast enough. That larger size comes at a cost of increased momentum: by the time the hawk is in position to take a swing at the smaller bird, the smaller bird is long gone. This is why most birds of prey attack by diving: the higher speed means that the target doesn't have a chance to dodge. --Serie 22:20, 4 May 2006 (UTC)
I guess they are little crows (or the like). We have a lot of house finches (brown with black/beige stripes). I don't think it is them because the attacking birds are clearly black. I don't know why they attack though because there are more than enough bunnies for the hawks (and gators) to eat. Those things multiply like, well, like bunnies. --Kainaw (talk) 00:46, 5 May 2006 (UTC)
I'm not very familiar with US birds so I couldn't tell you what species your little black ones are, but their behaviour sounds a lot like mobbing (see the 'in animals' section). The smaller birds see the hawks as a threat to themselves or their eggs/chicks and will engage in seemingly suicidal bouts of aerial combat (often in groups) with the predators to try to chase them away. Yummifruitbat 02:28, 5 May 2006 (UTC)
It turns out that one of the doctors here is a bird expert. He pointed out that they are not just crows, they are fish crows. The differece is the smaller size, the paler beak, and the wings have a sharper point to them when it glides. According to him, they send one or two up to fend off hawks when they find a good stash of fish, shrimp, crabs... whatever. They take turns keeping the predators busy while they eat. They will also buzz-attack cats. Now, I pretty much know all of the birds around my house and office. I just have to figure out what type of woodpecker I have in my front yard. It has the head of a cardinal and the body of a bluejay. Since my yard if full of cardinals and bluejays, I joke that he is a half-breed. --Kainaw (talk) 14:46, 5 May 2006 (UTC)
I don't claim to be an expert on woodpeckers, but I figured I'd do a little searching on this. Your woodpecker sounds a lot like Woody Woodpecker to me. According to this site, Woody is a Red-headed woodpecker. This species shows up on the South Carolina Breeding Bird Atlas [14]. Here's another site with pictures: [15], and another that shows their range overlapping Charleston: [16] Is that your bird, or is it much more blue? EWS23 | (Leave me a message!) 17:04, 5 May 2006 (UTC)
"The head of a cardinal" makes it sound more like a Pileated woodpecker to me - this has the pointed crest on its head and the red area is restricted to the crest rather than the whole head. It is found year-round in South Carolina. Alternatively it could even be an Ivory-billed woodpecker, but if it is you're very lucky as they're thought likely to be extinct in North America. Edit: Apparently there have been sightings/possible audio evidence of the Ivory-billed in Arkansas in 2004/5. Yummifruitbat 17:24, 5 May 2006 (UTC)
The head of the red-headed woodpecker is correct. It even has the darkened area around the eyes like a cardinal. The reason I'm not sure if the guy in my yard is a red-headed woodpecker is because all the photos of them have black and white bodies. This one has a blue jay body. It is blue, gray, and white. It isn't a pileated one because it doesn't have such a prominent pointed crest - just a little point. I'm sure that some day he'll be out there while I have my camera. Normally, I come home and see him fly away when I pull in. --Kainaw (talk) 19:03, 5 May 2006 (UTC)
I got in touch with our local bird-expert doc again. He said that the only local bird with a red head and a blue-gray body is the red-breasted sapsucker (our article says they aren't in South Carolina - hmmm...). The picture on Wikipedia has a black and white body. Also, the one I see in my yard has a clear ring aound the neck where the cardinal head is joined to the bluejay body. So, it is probably a freak woodpecker with a blueish body or a freak sapsucker with a gray breast. --Kainaw (talk) 19:17, 5 May 2006 (UTC)
While I haven't seen any pictures indicating as much, the drawings of Woody Woodpecker seem to indicate that red-headed woodpeckers can take on at least a bluish tint to their body, if not a completely blue body. Then again, maybe that was just the artist ad libbing and making something that was more appealing to the eye. Either way, it would be nice if you could get a picture at some point. EWS23 | (Leave me a message!) 23:30, 5 May 2006 (UTC)
(getting a bit indented!) The National Geographic Field Guide to the Birds of North America, 4th Edition agrees that the Red-breasted sapsucker isn't found in SC. The distribution map shows it confined to the West coast, not venturing very far inland. Apparently, however, it frequently hybridizes with the Red-naped sapsucker which extends as far east as western Texas in winter. This species sometimes hybridizes with the Yellow-bellied sapsucker whose winter range includes South Carolina. The two former species were previously considered subspecies of the latter, so perhaps you're seeing some weird combination of all three! :) Yummifruitbat 03:16, 6 May 2006 (UTC)

Chemical Reactions[edit]

Do all chemical reactions recquire activation energy, or are there some that have none, and will decompose almost instantaneousley in normal conditions (or even extremely low temperature) lfor example possibly something like NeCa4 or NeC2, involving noble gases (I can't imagine those compunds are to hard to pull apart). If not, what is the bond with the lowest activation/bond energy. Thank you Philc T+C 20:56, 4 May 2006 (UTC)

All chemical reactions have an activation energy. This energy can, however, be below average room temperature and many reactions occur spontaneously at 20C. A chemical reaction with no activation energy would still take place at absolute zero and since there's no kinetic movement at that point, no such reaction exists. As for the lowest bond energy, I'd say the van der Waals bonds holding liquid helium-3 together. GeeJo (t)(c) • 21:27, 4 May 2006 (UTC)
Well, first we have to define "chemical reactions" more precisely, because you could even claim that two electrons near each other flying apart (e^-_2\longrightarrow 2e^-) was a "reaction" that certainly required no input energy. There are certainly imaginable constructs of atoms with a positive potential energy and no containing energy barriers (meaning that they will fall apart spontaneously) like XeH20 or so. Indeed, probably the reasonable definition of "molecule" in the phrase "molecule with a bond energy of ..." is "an arrangement of atoms that requires energy to dissociate", guaranteeing that all bond energies are positive. Of course, there are synthesis reactions with 0 activation energy: consider Na++Cl- \longrightarrow NaCl. But that's not a bond energy at all. Anyway, it's certainly possible for the activation energy of a reaction (and/or the energy of a bond) to be \ll kT for many T (see Boltzmann's constant), so the reaction is usually spontaneous. But any reaction with a positive activation energy (including the analysis of all reasonable molecules) can be slowed arbitrarily (though never truly halted) by reducing the temperature sufficiently. At absolute zero, were it attainable, only the reactions with no activation energy at all (like the attraction of ions or the repulsion between random non-bonded atoms like the xenon-hydrogen nonsense) can proceed, and even then they raise the temperature back to something positive. Hope this helps. --Tardis 21:40, 4 May 2006 (UTC)
All chemical reactions have a reaction energy, which can be positive or negative. Isopropyl 22:38, 4 May 2006 (UTC)
Or zero. He's asking about the activation energy though, not the reaction energy. --BluePlatypus 00:15, 5 May 2006 (UTC)
All chemical reactions have an activation energy, which can be positive or negative. Isopropyl 02:35, 5 May 2006 (UTC)
Not all reactions necessarily have an activation energy and it is certainly never negative. If it was, the activated complex would be lower in energy than the reactant and/or product species. So it would be a stable or metastable state and the reactant and/or products would be unstable. So by any meaningful definition it can't be negative. --BluePlatypus 03:47, 5 May 2006 (UTC)
Ah, I see that your definition of reaction is one stable species to another; then you're right, of course. Isopropyl 03:53, 5 May 2006 (UTC)
Yes and no. It's all a matter of how you define "reaction", as mentioned above. Usually, a chemical reaction is the reaction from one stable species to another, where a stable species is by definition something which is at an energetic minimum. Since you're moving between two energetic minima, by the rules of calculus, there must be a local maximum of energy in-between. (potential-energy surfaces are continuous) So for a "reaction" to have a zero barrier, it must start from a state which is not an energetic minimum and thus not be a stable species to begin with (but possibly a metastable one). As was pointed out, the activation energy can be arbitrarily small though, including smaller than kT, which means it has no significance. But even at absolute zero you could, at least in theory have a spontaneous reaction, if the activation energy was comparable to the zero-point vibrational energy of the molecule. --BluePlatypus 00:15, 5 May 2006 (UTC)
As the Platypus says, the decay of excimers would be a reaction that doesn't require activation energy. When the excited state decays the molecule just comes apart. Dr Zak 01:13, 5 May 2006 (UTC)

Badgersex[edit]

I've heard badgers are the species which have sex for the longest time, can anyone verify/specify? Thanks in advance!

According to here badgers can go at it for up to 1.5 hours. Can't find verification that it is the longest among "big" animals. According to this page the longest (albeit not voluntarily) coitus occurs between some insects, for up to 60 hours. (I wonder if the good folks at Google ever read their server logs to see what people search for. "Badger intercourse"...) Weregerbil 10:23, 5 May 2006 (UTC)
I'm told there's a ticker at Google HQ showing some of the things people are searching for. As for how long various animals last, I've been hearing ads on the radio for some kind of impotence treatment that mentions some statistics. I'm pretty sure they mention that the mink lasts some large time, but I can't remember how long - a Google search suggests 8 hours. Confusing Manifestation 12:08, 5 May 2006 (UTC)
I believe I heard the mink was able to have an orgasm for eight hours, not counting the actual intercourse.

Please God, in my next life, let me be a mink! Loomis51 02:14, 7 May 2006 (UTC)

Oh, please. Humans can do it for longer if they try. You just mix a little foreplay every once in a while in with the actual...uh...dippity doo. Cernen Xanthine Katrena 14:07, 7 May 2006 (UTC)

Photons and EM interaction[edit]

Photon says "electromagnetic interaction is mediated by the exchange of virtual photons." Does that mean that there are constantly virtual photons exchanged between every pair of charged particles in the universe? If so, that is a lot of photons, and they last a long time. Bubba73 (talk), 23:10, 4 May 2006 (UTC)

Well, they're called "virtual" for a good reason. They're not actually real, they're just possibilities of photons, which taken together average out to explain the well-known force. —Keenan Pepper 23:58, 4 May 2006 (UTC)
You can think of it that way, but you can calculate the average rate of virtual photon exchange between two charged objects, and it is enormous. So yes, there are constantly photons exchanged between everything, and yes that is a lot of photons. -- SCZenz 00:10, 5 May 2006 (UTC)
Yes, but I thought that virtual photons could exist for only a short time. These must exist for billions of years, right? Bubba73 (talk), 00:14, 5 May 2006 (UTC)
For one thing, virtual photons can go faster (or slower) than the speed of light, so they don't necessarily take billions of years to travel between charged particles billions of light years apart. This is okay because they can't carry information. For anothing thing, it's not true that virtual photons can only exist for a short time. The only definite rule is that they can't be observed, or else they're not virtual anymore. —Keenan Pepper 03:56, 5 May 2006 (UTC)
Thanks, I didn't know that. I thought they could only exist for a short time because of Delta T in the uncertainty principle. Why can't they be observed? How does a particle detector know the difference between a virtual photon and a real one? (I hope this isn't a stupid question.) Bubba73 (talk), 03:40, 6 May 2006 (UTC)

salmonella[edit]

In Australia, we have a current affairs "news" show called Today Tonight. now, this show is notorious for bullshit, but i wanted to know more about it's report on salmonella. they reckon around 70% of cooked chicken availiable here has salmonella. This would infer that around %70 of australian chicken eaters would get salmonella related diseases right? of course I've never come across any thing worth believing that says our chicken is unsafe. The explanation given on Today Tonight is that our immune system will fight the salmonella, but if we keep eating the chicken eventually our system will give up. I always thought that if we fought something once sucessfully, we would become immune to it! The story focussed on a bloke who is now in a wheelchair because he ate too much chicken, but i thought salmonella just made you quite ill. I read the wikipedia article on salmonella which says "In March 2006, The New York Times reported that the US government said that 16.3% of all chickens were contaminated with salmonella". and i havent heard of huge worries in the states either.

Is this just more b/s from naomi "F..king" robson, or should i switch to beef?

Thanks --Ballchef 23:51, 4 May 2006 (UTC)

Beef? Haven't you heard of mad cow disease? Or is that just over here? Black Carrot 00:15, 5 May 2006 (UTC)
"Naomi Robson" and "mad cow" is a very pleasing juxtaposition. JackofOz 02:19, 5 May 2006 (UTC)

You always assume that the raw chicken is covered with nasty buggers, salmonella being very common. That is why the official 'cooked' temperature is much higher than beef. Well-cooked chicken has no bugs, and always use a neato very geeky electronic thermometer that beeps at you! --Zeizmic 02:16, 5 May 2006 (UTC)


Chicken is commonly contaminated with pathogenic salmonella and campylobacter species, as are chicken eggs. If you have ever visited a chicken farm and viewed first-hand the conditions under which poultry are raised, it should not be a surprise. Most of these disease-causing bacteria are effectively killed by thorough cooking. A good web site describing safe food practices is Safe Tables Our Priority (S.T.O.P.).--Mark Bornfeld DDS 03:19, 5 May 2006 (UTC)
You should always treat raw chicken as if it is covered in poison; this is a fundamental rule of working in a kitchen. This means considering everything (hands, surfaces, knives) that comes into contact with raw chicken as contaminated, until washed. Commercial kitchens may have separate colour coded knives, chopping boards etc.; in a domestic kitchen, it is considered very important to wash hands, knives etc. once contaminated. If you take the same knife to chop up salad, there is a good chance someone will get sick. Salmonella is only one of the nasties you might find on raw chicken. Cooking is considered to destroy all of the nasties. So, there may be a grain of truth in the article, which is a much as most press reports manage. (Raw eggs are a difficult area; some things like mayonnaise need raw eggs. In practice this means that commercial kitchens take pasteurised eggs, and domestic kitchens take a chance.) Notinasnaid 10:05, 5 May 2006 (UTC)
On the immunity assumption above. There are some things for which immunity is lifetime or at least very long. There are other things (tetanus, for instance) for which immunity wears off (in this case soem years). And there are some things for which there is no immunity retained after an infection encounter. I've never come across an explantion that seemed credible.
On the question of why everyone isn't infected with salmonella from having anything to do with chicken, well... We live in a sea bacteria and viruses. Few of them are pathogens for us, to be sure, but more than enough to be comforted are. So why aren't we always infected and mostly dead anyway. Several reasons are known. One is a community effect in which already present bacteria deter additional bacteria from becoming established. There is even some research about using this effect on chckens. If they are inoculated with a cocktail of benign organisms, then malicious ones are discouraged. And second, what we eat has to pass through a stomach which is actively maintained in a quite acid condition. Most organisms can't survive it. The low pH isn't really required for digestion and seems mostly to be a protective arrangement. 71.249.12.89 06:56, 11 May 2006 (UTC)

May 5[edit]

Speed of a 747 at 500 ft[edit]

My house lays just under the approach path of a major international airport. Watching the majestic 747-400s flying over my house on their final approach is a daily pass-time of mine. I just wonder: what is their airspeed at 500ft of altitude?--JLdesAlpins 00:24, 5 May 2006 (UTC)

Bear in mind that I'm not a pilot and this is all speculation, but 747s are probably going really slow at this point. When they're only 500 feet above ground, they're trying to trimming back speed so that when they touch down they're just about stalling. I forget how fast that is for a 747 but my guess is like 120 mph or so. Isopropyl 02:34, 5 May 2006 (UTC)
A bit of googling indicates a short approach speed of about 160-180 kts and a landing speed of about 150. Conversion of the landing speed gives 172.6 mph or 277.8 km/h. The approach speed at 500 ft should be pretty close to the landing strip I guess so the speed would be a bit above that too. - Dammit 07:32, 5 May 2006 (UTC)

Shoot and Unlock[edit]

An Hollywood's favorite: a guy shoots at a lock with a pistol and the lock shatters. Would a good quality lock break apart by being shot at in real life?--JLdesAlpins 00:30, 5 May 2006 (UTC)

No. Bullets are extremely fragile and locks are extremely sturdy. In the 70s (if not earlier) Master Lock ran commercials where they shot locks and showed that they still remained locked. --Kainaw (talk) 00:40, 5 May 2006 (UTC)
OK. I Googled and found this site where they were able to shoot a lock off using a 12 guage slug. That is similar to using a .50 cal (which will go through a tank's armor). So, I wouldn't consider that a normal "shoot a lock and it comes off" scenario. --Kainaw (talk) 00:43, 5 May 2006 (UTC)
Nice find. – b_jonas 11:51, 6 May 2006 (UTC)
Does the lock really shatter, or perhaps the hasp does? User:Zoe|(talk) 03:02, 6 May 2006 (UTC)
It is nearly impossible to shoot the hasp off. It is a curved surface. Ignoring the impossible rare scenario where the tip of the bullet strikes perfectly into the extremely thin smooth front edge of the hasp - the bullet is going to turn and move off to the side with the easy-to-pass-through air and away from the hard-to-pass-through hasp. In the examples on the site that I found, the goal was to break the locking mechanism inside the lock. On that site they did mention that it is possible to slowly widdle away at the hasp by shooting it over and over all day long. --Kainaw (talk) 19:31, 6 May 2006 (UTC)
I really hope you mean whittle away at it. To widdle away at a lock means something entirely different. DJ Clayworth 19:26, 10 May 2006 (UTC)
Well, it isn't that far off... a rifle is commonly used as a phallic symbol and the method described would be spraying it randomly over a long period of time. --Kainaw (talk) 20:27, 10 May 2006 (UTC)

Oil Production/Reserves[edit]

I'm sure this information is available on some wiki site(s), but I've tried, and I'm finding it difficult to find the precise site(s) to look for.

I would like to find out the top 10 Oil producing countries, in terms of barrels of oil per day produced, as well as the top 10 countries according to their potential production, i.e. the top 10 countries with the highest amount of petroleum reserves whether exploited or not, within their territories.

Some other pieces of information I'd be interested in would be:

1) At the current rate of consumption, approximately how long would it take to completely exhaust oil reserves (i.e. there'd be nothing left to pump) in such oil rich states as Saudi Arabia, Iraq and Iran in particular, and other states in the Middle East in general;

2) The degree to which Canada exploits its oil reserves, in relation to the degree to which these Middle Eastern countries exploit their oil reserves. (For example, if Saudi Arabia has 100x in oil reserves, and produces 1x per year, it's exploiting 1% of its oil reserves per year). What percentage of Canada's oil reserves are exploited each year? Thanks for the help. Loomis51 01:16, 5 May 2006 (UTC)

We don't know to precision how much oil is really down there, and you can bet that Saudi Arabia wouldn't say the found values. They would exaggerate them considerably if they did. Template:OPEC should help as a list

-- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 04:25, 5 May 2006 (UTC)

This is a difficult issue, and there is not much consensus on it. See our article on petroleum - in short, oil reserves are not like giant vats which have a set quantity in them. The oil is scattered throughout rock layers, and mixed to varying degrees with other substances. Current thinking is along the lines that, for the forseeable future, oil will almost never run out, just become ever more expensive (both in terms of money and energy needed) to extract, until we reach a point (barring, or even with, further advances in technology) where the energy/money needed to extract the oil becomes greater than the energy/money which would be gained by using the oil, at which point it no longer becomes viable to extract it (see the article for details on some ideas). At which point this will happen is extremely difficult to predict, but what can be safely assumed is that oil prices will continue to rise as global demand is rising, supply is barely keeping up, and the costs of extraction are rising also.
For the same reason, you can't tell "how large potential oil reserves are", so I'm afraid all your questions (save for the one about current production, where MacDavis has already pointed you) are unanswerable. — QuantumEleven 06:41, 5 May 2006 (UTC)
Top 10 oil producing countries in terms of barrels per day - this is likely to be hard to find as most frequently oil is measured in terms of oil reserves still in the ground (which, assuming its even pubicly available, is usually massively overestimated as OPEC assigns its production quotas on the basis of stated reserves) rather than daily production which is quite variable, not constant and depends on a number of factors.
Your question 1) is probably irrelevant as the current rate of production won't remain stable over time. It varies a lot now depending on capacity, demand & OPEC limits (though there is evidence that OPEC is pushing at the limits of its productive capacity). Once we get to the global oil production peak we'll be able to produce less each year (on average) - but demand will be higher than supply so attempts will be made to expand production by investing in new infrastructure/exploration, etc. This may lead to increased production in the short term (reducing the time before it is 'all' extracted) but over the longer term wouldn't make any difference. Incidentally it isn't possible to extract all the oil in any particular field, I believe due to geology about 70% is the maximum that can be extracted. The Saudis are currently, reportedly, pumping water into their Ghawar field inorder to squeeze every last drop they can out of it but they'll never take all the oil out, just all the recoverable oil which is what the reserves are based on. Technological advances could in theory increase the recoverable reserves but this is unlikely as over the past 30+ years so much money has been invested in oil extraction technology that they've advanced the capabilities of the technology about as far as it can go.
On point 2 there are a few problems, 1 - oil reserves are hard figures to be accurate on, as Quantumeleven says, even where they aren't purposefully overestimated by governments or oil companies (as Shell did with its Nigerian reserves). 2 - How do you define oil reserves, or even oil. A lot of attention is being paid to the Athabasca Oil Sands (which together with oil shale is, I think, a large proportion of Canadas oil reserves) however extracting oil from this source requires a lot of gas to be expended in the extraction process in the first place (0.4 million cubic feet of gas to produce 1 barrel of oil) and is only viable if the oil price remains high. Also as we exhaust this resource it'll take more gas to produce the same amount from oil sands until the point where it noone will bother as there won't be any money in it (or gas is running short too). AllanHainey 07:55, 5 May 2006 (UTC)
You may want to read Oil_reserves#Canada which gives some info on Canadian oil reserves, & the rest of the page for other countries oil reserves. AllanHainey 08:11, 5 May 2006 (UTC)

Thanks to all of you, the subject is obviously even more complex than I had originally thought. Loomis51 01:00, 6 May 2006 (UTC)

Thermal burns and metabolic acidosis[edit]

Can anyone tell me what causes metabolic acidosis in burn victims? Is it caused by the loss of bicarbonate during third spacing? Is it caused by inhalation poisoning such as cyanide? Or is it caused by hypermetabolism? What is the doctor looking for when he/she orders an immediate Arterial Blood Gas in trauma/emerg? What is he/she monitoring for when he/she orders ABGs later on in ICU or acute care? Thank you for your time! Student nurse in a current heated discussion with fellow student nurse.

I have no idea at all, but maybe our article acidosis might help? --HappyCamper 02:54, 5 May 2006 (UTC)

I understand acidosis and how it happens but not in the pathophysiology related to thermal burns.

I'm just thinking off my head so please take this with a grain of salt...but when someone is an acute burn victim, does that mean they lose a lot of body fluids? And when that happens, doesn't that shift the some sort of equilibrium in the bloodstream involving water, carbon dioxide, and bicarbonate ions? And doesn't hyperventilation do something too? I somehow don't think cyanide is involved...perhaps carbon monoxide if anything...I imagine that burn victims would be exposed to more CO gas simply because of partial combustion...from your local uninformed Wikipedian...Wait a bit longer, I know there's at least one Wikipedian out that who could probably help you... --HappyCamper 04:06, 5 May 2006 (UTC)
Yes! yes! yes! All that and a little bit more... that's exactly what fluid shift or third spacing is and that is my educated opinion of what happens... the fluid shifts out of the vascular and takes the bicarbonate with it... my colleague insists it's because of SNS response and the loss of the skin's ability to insulate causing the hypothalamus to increase the metabolic system into overdrive or "hypermetabolism". While I agree this may be a possible additional additive to metabolic acidosis - I disagreed that it was the reason that ABG's are drawn immediately in ER. The third possibility is toxins inhaled during the burn incidient causing carbon monoxide toxicty. However, I have found little research anywhere to support any of these theories or even if it's a combination of them. Burnsurgery.com mentions unexplained acidosis may be due to toxicity but no where can I find it explained. --StudentNurse 10:51, 5 May 2006
Are we talking about acute burn victims just arriving at the hospital? Well, I suppose most things in science are a mixture of reasons. There might be something predominant which is important. What I'm thinking is something like
H+ + HCO3- <-> H2O + CO2
See, I'm not so sure whether fluid loss in itself would cause the blood to become more acidic. Think of it this way: you have some vinegar (we'll pretend that's the blood). Now, you pour a little bit down the sink. The vinegar left in the jar is still just as acidic as it was before. The concentration (not the absolute amount) of acid ions needs to change in order for the pH to change. But let's assume your scenario. Lots of fluid loss. Don't really know if this happens, but say the body goes into shock. Let's make it even worse. The burn wound is diseased, causing the body to go into septic shock. Does *this* cause the the production of less bicarbonate ions? If so, then the equilibrium will shift to the left, making the blood more acidic. Now, I imagine the victim starts to hyperventilate to compensate. Breathing causes the CO2 on the right side of the equation to go away, shifting the equilibrium back. I would imagine this mechanism to be part of the sympathetic nervous system. I certainly don't want to be conscious of how I need to breathe in order to regulate my blood pH! Now, as for the Arterial Blood Gas stuff. My *guess* is that it is standard routine for acute burn victims - the rationale being "let's find out how our patient is doing so we can treat the appropriately". Maybe there are IV drugs you can add to help with the acidosis or something? When the patient is in an intensive care unit, I would hope that whatever medical intervention helped bring the blood pH back to normal. If it's not normal, then additional things need to be done (and thank goodness there are people who study this!) That's my guess. So yes, it's quite possible to see that both your friend and your perspective can be go together hand in hand. But you know, I think you're right to pinpoint the bicarbonate ions first. There isn't a reason for the hypothalamus to kick in unless something fundamental in the biochemistry changes. But, I'm a rather uninformed Wikipedian - and my bias is towards the chemistry, rather than the biology :o) Cheers! --HappyCamper 14:42, 5 May 2006 (UTC)
If you're still wondering: Its like any major injury, just more major: Burns leads to hypovolemia (intravascular fluid loss), leads to shock, leads to cellular hypoxia, leads to acidosis. Acidosis: related to extent of injury and duration. Recovery from acidosis indication of effective treatment. Pulmonary injury: due to burns upper airways and toxic gases lower down. Inability to breathe adequately and development of acute respiratory distress syndrome. Toxicity: HCN blocks aerobic cellular respiration, in the presence of normal oxygen tensions. CO causes inadequate oxygen delivery in presence of normal oxygen tensions and adequate hemoglobin. Both can cause acidosis, but cannot be diagnosed by routine ABGs (for CO: unless HbCO is routinely done). Later on (5 days+) hypermetabolism can caused increase CO2 production and respiratory failure (respiratory acidosis, not metabolic) if muscles are exhausted. Sepsis also a later cause for shock and metabolic acidosis. Acidosis as such, if severe, causes dysfunction of all the vital organs. --Seejyb 19:50, 7 May 2006 (UTC)

Second law of thermodynamics[edit]

we have seen each law has some or other exxeptions or failure so is there any thing in this world that does not follow 2nd law of thermodynamics. If any body elaborate on this i will be very thank full


sujay

The assumption that "every law has an exception" is not a good starting place for logical reasoning. As far as we know, everything follows the second law of thermodynamics. —Keenan Pepper 03:52, 5 May 2006 (UTC)
Well, even the second law doesn't describe quite everything. See the fluctuation theorem. It is absolutely beautiful. But read very carefully what it is really saying though. --HappyCamper 03:59, 5 May 2006 (UTC)
Don't listen to them. Wikipedia is lying here. It is possible to circumvent the second law of thermodynamics and gain energy from the vacuum. Someone even tried it, but they are silenced by the governments controlled by the global oil maffia, and the academic bigheads who don't like to be proved wrong didn't even allowed them to publish eir thesis. Now ey's alone and chased anywhere around the world and without material support he cannot build eir dream machine that would make infinite energy for free and change the whole world. :) – b_jonas 11:41, 6 May 2006 (UTC)
Myes, it worries me, there are people gullible enough to believe that. Mabye you should make it more clear you are being insincere Philc TECI 22:37, 8 May 2006 (UTC)
You can't hear it, but I'm giggling on the inside =) --mboverload 01:02, 12 May 2006 (UTC)
Sujay, the second law arises from probability and statistics. Take for example the reason why you can't get heat conduction going from a cold object to a hot one. Heat conduction happens by molecules transferring energy when they collide. Now you will get some of these collisions between molecules transferring energy from the cold object to the hot object, but you will get more of them transferring heat from the hot object to the cold one because for each collision that is the more likely outcome. If we're talking about hot and cold objects which are the size of everyday things, they will contain such a huge number of molecules that statistically you can be 99.99999999999...etc...% certain that the heat will go from the hot to the cold, even if you could in principle get an exception where it goes the other way. Arbitrary username 15:28, 6 May 2006 (UTC)
Exactly. It's hard to define what an exception to this law would be, because it states that matter tends to become more disordered. Of course, sometimes entropy decreases, but only on an extremely micro scale, and only completely randomly. But the law holds up extremely well: on any reasonable scale, for any reasonable amount of time, it always requires work to decrease disorder. --Leapfrog314 03:45, 12 May 2006 (UTC)
Well, keep in mind the actual premises of the Second law of thermodynamics: it strictly applies

only to an isolated system (i.e., one that exchanges neither mass nor energy with its surroundings). It is my understanding that the law is true without exceptions within that context. All examples given above (statistical collisions of molecules and local decrease in entropy) assume exchanges of mass or energy, so they are not examples of the application of the law, nor do they provide 'exceptions'. --Michel M Verstraete 20:44, 12 May 2006 (UTC)

Eating "Instant Krazy Glue"[edit]

Today, I accidentally got half a drop of super glue on my thumb and index finger, but fortunately pulled the fingers apart before the glue dried. I have the bad habit of biting pieces of skin off my fingers and then swallowing them, so that's what I did to the fingers which had a layer of dried glue on them.

I think I ate around 0.02 mL of Instant Krazy Glue. After biting my fingers, I noticed this message on the glue container: "If swallowed, contact a Poison Control Centre or doctor immediately. Do not induce vomiting." I have two questions:

  1. What are the symptoms of swallowing large amounts of Instant Krazy Glue?
  2. Is swallowing 0.02 mL enough to cause noticeable effects? I would think not, unless the glue is a very strong poison (which I really don't think is the case). --Bowlhover 03:59, 5 May 2006 (UTC)
I think the Poison Control Centre (you know, the one that the label told you to call) would be able to answer you. - Nunh-huh 04:20, 5 May 2006 (UTC)
No, no harm has been done to you, don't worry. Cyanoacrylate (super glue) was even used by medics in the Vietnam war to glue wounds shut. -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 04:25, 5 May 2006 (UTC)
grr edit conflict.. Nope you are fine. I don't know what is in it and the website is completely useless, but a good rule of thumb is if kids can use it without adult supervision, it's not going to hurt. Sifaka talk 04:21, 5 May 2006 (UTC)
lol, I was just edit conflicted right before you. -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 04:31, 5 May 2006 (UTC)

Thanks everyone! --Bowlhover 02:36, 6 May 2006 (UTC)

pentium lga[edit]

what is lga stands for in pentium IV 2,66lga ???

Land Grid Array. -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 04:29, 5 May 2006 (UTC)

Is everything bendy?[edit]

For all of the materials we now know about, do all of them have some degree of 'bendy-ness'? (bendability?)

If we have a diamond a mile long, could we measure the amount we could bend it and the force needed to do so? --Kickstart70-T-C 06:18, 5 May 2006 (UTC)

Well, you can predict the amount of force at home! It would involve the shear modulus, which is finite even for diamond; the details depend on how far you bend it and the cross-sectional area. You can find the data here, if not on Wikipedia somewhere I haven't looked.
In other news, Shear modulus could use a table of typical values, if anyone's interested... Melchoir 06:23, 5 May 2006 (UTC)
Done! Isopropyl 07:07, 5 May 2006 (UTC)
.....I ... I am all-powerful! Behold my works, ye mighty, and despair!
(I mean, thanks) Melchoir 07:18, 5 May 2006 (UTC)

Thanks to both of you, much appreciated! --Kickstart70-T-C 16:33, 5 May 2006 (UTC)

Perfect rigidity is a violation of special relativity. It is no more possible to have perfectly rigid body than it is to travel faster than light. Therefore, yes, all materials are bendy. -lethe talk + 01:46, 6 May 2006 (UTC)

Mouse Trap cars[edit]

Does anybody know the best technique used to making a car from a mouse trap? there are heaps of websites on this topic but all are just trying to sell mouse trap car kits. so if anyone knows how to make one or if they know any good websites it would be very much apprecaited.

Thank you

Try here (simple model) or here (more advanced model). Gandalf61 09:27, 5 May 2006 (UTC)
Are you going for speed or distance? If it is distance, the ones that use the moustrap spring to wind up a clock spring tend to go the farthest at a very slow speed. --Kainaw (talk) 20:44, 5 May 2006 (UTC)

internet definition please[edit]

hello may i know the definition of internet and world wide web and their uses

thank you

See internet and world wide web. Dismas|(talk) 08:53, 5 May 2006 (UTC)
(darn you for getting there faster, Dismas! :)) The World Wide Web is one part of the Internet. We have excellent articles on both: Internet and World Wide Web. If you have any questions after reading the articles, you can come back here. — QuantumEleven 09:04, 5 May 2006 (UTC)

Menstrual cycles and the possibility of conception.[edit]

If my girlfriend and I had unprotected sex on the evening of March 6th/morning of March 7th, and her cycle started March 4th and apparently ended March 6th, is it possible that the aforementioned unprotected sex resulted in conception?

-Thanks, Jared

Less likely but certainly possible. See fertility awareness.-gadfium 09:30, 5 May 2006 (UTC)
If it did result in conception, and unless there were an early miscarriage, she would be in about her ninth week, and an over-the-counter pregnancy test would tell you for sure. --Ginkgo100 23:15, 5 May 2006 (UTC)

the above is completely correct but see to it that the next time you hav sex with your girlfrnd use a condomn and then enjoy it the better way.-priyanka

speed of light[edit]

what happens if one travels at the speed of light? I know its impossible but i want to know

You might find Faster-than-light of interest as well as special relativity. Dismas|(talk) 10:13, 5 May 2006 (UTC)
(Grr!!! Edit conflict!!!!) Your mass will keep increasing until it becomes infinity when you reach the speed of light. And you would stop moving because you would need infinite amount of energy to keep you at that speed. . But in short, we dont know what will happen because noone has ever travelled at the speed of light. I'd suggest you to read [this as it answers your question to a certain extent. Check back if you have anymore doubts. Jayant,17 Years, Indiacontribs 10:18, 5 May 2006 (UTC)
I'll modify an answer I gave at Talk:Speed of light. First of all, yes, it's impossible. That said, if you do accelerate to the speed of light, in your own reference frame, the very same instant you achieve that speed you will simultaneously slam into your ultimate destination, no matter how far away it is. If you like, this result is time dilation in the extreme; for every second that passes in someone else's reference frame, you experience 0 seconds. Since you can't pass time while cruising at the speed of light, you can't perform experiments or make observations, so in some sense, nothing happens. Melchoir 10:25, 5 May 2006 (UTC)
Pardon my ignorance/scepticism, Melchoir, but if it's impossible then ... it's impossible (even for all-powerful beings such as yourself). You could accelerate as arbitrarily close to the speed of light as you like, but you could never reach it. Therefore there would never be such an instant as you describe. Unless it wasn't really impossible after all. This sounds a bit like "You can never count to infinity, but if you could, the number would be <xxx>." JackofOz 10:51, 5 May 2006 (UTC)
You're right of course, but with some effort I could probably defend my interpretation. As in, draw a smooth, mostly timelike world line with a lightlike section included, parametrize it by proper time, and interpret that as someone's history of experiences. Sure, there are continuity problems, and it's kinematically forbidden for a massive particle to actually follow the path. But if you interpret the math liberally, what I said makes some kind of sense. Melchoir 11:04, 5 May 2006 (UTC)
Thank you. I would continue this Friday night frivolity, but I think it's kinematically forbidden. :--) JackofOz 11:14, 5 May 2006 (UTC)
I think it's perfectly reasonable to take your description of travelling along a lightlike path as simply what it's "like to be" a photon or other massless particle. I know some people don't like ascribing imaginary experiences to non-conscious POVs (to the point that many Wikipedia articles are less clear than they could be to avoid the issue), but I personally have less trouble imagining the perspective of something that cannot possibly be sentient than swallowing local portions of globally forbidden worldlines and what have you. --Bth 11:25, 5 May 2006 (UTC)
I think the best way to understand Melchoir's comments is as a limit. The correct description of what happens as you increase your speed becomes arbitrarily close to what Melchoir describes. The length of proper time to reach your destination becomes arbitrarily small, etc. -lethe talk + 01:44, 6 May 2006 (UTC)
See I am driving my car at the speed of light and I turn on my headlights. What do I see? and other questions from the Usenet Physics FAQ. – b_jonas 10:29, 5 May 2006 (UTC)
To be pedantic, it is possible to travel faster than the speed of light, just not in a vacuum. This is usually where someone brings up Cherenkov radiation. GeeJo (t)(c) • 11:05, 5 May 2006 (UTC)
That confuses some people, though, due to the conflicting meanings of the speed of light. It isn't possible to travel faster than 186,000 mph (c, the speed of light in a vacuum), but it is possible to travel faster than the speed at which light travels through some materials. Even then, you might say that the "light" (photons) doesn't really travel any slower. - user:rasd
Yes, the Physics FAQ talks about whether Faster Than Light Travel or Communication Possible, but it seems that wasn't what the original question was. (Faster than light travel is impossible only because whenever anyone finds a way to do it, physicians redefine "faster than light" not to include that.) – b_jonas 10:58, 6 May 2006 (UTC)
No, it's just that all the 'exceptions' that get mentioned are pretty much useless. Sure, a shadow can "move" faster than light, but what's the point of something that can't pilot a ship across intergalactic space? Black Carrot 21:36, 12 May 2006 (UTC)

manufacture of lighting fittings[edit]

I would like to know how lighting fittings are manufactured. The process involved from sourcing the materials used to the final product. i would be grateful if the information could be broken down to specific lighting fittings. Also the what are the references of regular bulbs to low energy ones.

Incandescent light bulb Andrewjuren(talk) 08:58, 6 May 2006 (UTC)

Reflection[edit]

Why cant a plane mirror and a highly polished white surface produce reflection of the same kind?

Well, a white, shiny car is white. It has been painted white, and so it is only natural, indeed demanded, that it's most dominating reflection is white. This is because of pigments that WILL suck up light on certain frequencies, and reflect light on other frequencies. Thus, seeing yourself in the mirror image on a white car hood, you see yourself in shades of white, because all other colours are absorbed. A plane mirror is not coated with such pigments, unless artificially added, and reflects nearly all frequencies. I think most plane mirrors, when cleaned very well, can produce as much as 70-85% reflection. Thus, plane mirrors DO suck up some light, you just don't see it very well. 213.161.189.107 13:08, 5 May 2006 (UTC) Henning
Er, white light is made up of all (visible) frequencies ...
The difference between a mirror and a general white surface is smoothness. A smooth surface like a mirror will give specular reflection, but light hitting a rough surface will be scattered at different angles depending on which particular little part of the surface it hits -- diffuse reflection. --Bth 13:55, 5 May 2006 (UTC)
So basically, a highly polished white surface will no longer be white; it will reflect like a mirror if you polish away all the surface roughness. Neh? Skittle 16:26, 5 May 2006 (UTC)
I would think so. As long as it was highly polished. --Bth 17:50, 5 May 2006 (UTC)
If you ask someone what color a mirror is, don't they say "silver"? So, I think a highly polished silver car would have the effect of a mirror. --Kainaw (talk) 19:56, 5 May 2006 (UTC)
No, a white surface will never become a mirror no matter how long you polish it. The difference is that a shiny white surface has a transparent coating and then a microscopically rough white surface underneath. Some of the light reflects off the outer surface, forming the reflection, but most of the light passes through the transparent layer, is scattered off the white surface, and passes back out in a random direction. In a mirror, both outer and inner surfaces are microscopically smooth, so they both produce reflections. —Keenan Pepper 01:00, 6 May 2006 (UTC)
Yeah, I've always thought of mirrors as silver, and shiny silverness as mirror-like. Any color material can be made reflective, by reducing scattering of the light (polishing it), but anything reflected in it would appear really red/blue/whatever, like looking through a color filter. What exactly is the color silver, in terms of the additive spectrum? Black Carrot 22:19, 5 May 2006 (UTC)
A reflective red surface would look red (or "metallic red"), a reflective blue surface would look blue (or "metallic blue"), and a reflective white surface would look silver (or "metallic white"). True silver color is the same as white, as I understand; the difference is the degree of reflectiveness. --Ginkgo100 23:18, 5 May 2006 (UTC)
Silver is simply reflective/metallic gray. —Keenan Pepper 01:01, 6 May 2006 (UTC)

Butterflys[edit]

Last night (may 4th), I was in a play. Right before I heard my cue line I was feeling really nervous. I also had some "butterflys" in my stomach. What I was wondering was what are these called (the butterflys) and why do they feel like that. I already looked at the article anxiety but to no avail. I was just curious. THanks. schyler 11:53, 5 May 2006 (UTC)

I learned a new word today: Glossophobia --Zeizmic 11:56, 5 May 2006 (UTC)

While I also learned a new word, it didn't really answer my real question. What is the name for the butterflys, not the name that butterflys is a symptom of. Thanks though. schyler 12:16, 5 May 2006 (UTC)

It seems that butterflies (pedantic note: remember -y pluralises to -ies in most cases) is what it's called. Certainly, our Butterflies in the stomach article doesn't give an official name and even a rather worthy article on thePhysiology of the Stress Response doesn't use any other term (it explains it as a reduction of activity in the digestive system as a response to stress, if you're interested; on the other hand, this article claims it's the result of a second brain in the stomach. We report, you decide.) --Bth 12:34, 5 May 2006 (UTC)
Your stomach (and esophagus, small intestine, and colon) contains brain tissue. It functions like a normal brain, just small in comparison to the brain in your head. When you have a sudden fear, the brain in your head releases hormones to prepare the body to fight or flee. The sensors in the lower brain pick those up and charge up for action. The charging and discharging of all those sensors is what the brain in your head is picking up as butterflies. --Kainaw (talk) 12:53, 5 May 2006 (UTC)
Ahhhh, I made the mistake of skimming the top of that article and thinking it was a joke. (I still think it's a misleading use of "brain"; by that standard the spinal cord is a brain too.) --Bth 13:48, 5 May 2006 (UTC)
The spinal cord is not capable of making decisions and controlling parts of the body on its own. The brain tissue in the abdomen is. That is how a person with a completely severed spine is still able to have a functioning digestive system without input from the brain through nerves. Of course, the hormone communication between the brain and the rest of the body continues to function - but going in to that is just too technical for the question a bout butterflies. --Kainaw (talk) 14:27, 5 May 2006 (UTC)
D'you know, it'd never even occurred to me to think that there might be a problem with digestion for spinal cord patients -- very interesting.
But what about the other two parts of the autonomic nervous system -- the sympathetic and parasympathetic, both of which are based in the spinal cord? And of course reflex actions are responses to stimuli that don't involve the brain at all. --Bth 14:41, 5 May 2006 (UTC)
Automatic and reflex actions are controlled in the brain stem. You could argue that the brain stem is the top of the spinal cord. You could say it is the bottom of the brain. Either way, it is completely different in structure than the spinal cord. --Kainaw (talk) 14:55, 5 May 2006 (UTC)
Reflex arc claims "A reflex to a stimulus is almost simultaneous, as the reflex arc doesn't involve the brain at all." Does it need correcting? --Bth 16:03, 5 May 2006 (UTC)
That is the difference between a brain stem reflex (ie: burning your elbow and jerking your arm - which most reflexes are) and a reflex arc. There are many reflex arcs in the body and they do not all go through the spinal cord. For example, loud noise causes an acoustic reflex arc in the eardrum which constricts the stapedius muscle. A hiccup is a reflex arc but I don't remember the exact nerve that triggers the diaphram to contract. Regardless, it is a reflex arc. But, reflex arcs are controlled by neurons. They are hard-wired connections from a receptor (usually a nerve) to a reactor (usually a muscle). Trigger the nerve and the muscle contracts. So, because the spinal cord is a conduit for nerves, some of which traffic reflex arcs, does not put it anywhere near the classification of neuron formations in the digestive tract or brain. --Kainaw (talk) 17:01, 5 May 2006 (UTC)

Since I was dissed, I have to go back to the original question. I looked up stage fright and that led me to that fancy name. I always thought that butterflys (ies?) was the only symptom. What we have found out is that there is no Latin name for 'butterflys' alone, except 'weird reaction by your second brain - itis'. (Geez, I feel like ol' Noti!) --Zeizmic 17:35, 5 May 2006 (UTC)

Welcome to my world. I am a computer programmer working in a building full of doctors. I mention that I have a bump on my finger - a wart to any normal person. They spit out a bunch of weird latin words. Also, they ask for data reports on things like "hypercholesterolemia". What's that? High cholesterol to any normal person. If it wasn't for wikipedia, I'd never get by when asked for things like "nephropathy" or "gfr scores". On the flip-side, I got a shipment of 12 optical mice in. I sent out an email asking which doctors didn't have an optical mouse so they could be replaced. Most responded asking what an optical mouse is. --Kainaw (talk) 18:03, 5 May 2006 (UTC)

English not providing you with all the features you need? Don't dispair make it up. If you want a pseudo-Latinate word for that squirty feeling, try combining some of these funky elements:

lepidopter- : butterflies, moths duoden-, abdomino-, ventro-, ileum : various gutty bits

Unfortunately most of these are suffixes but I quite like ventrolepidopter and I would tell people about them if I did not have them. Bonus word of the day borborygamiphobia, fear that someone will hear your stomach rumbling. MeltBanana 16:05, 6 May 2006 (UTC)

Nuclear bombs in phase[edit]

I heard a nuclear bomb has an energy efficiency of about 3%. Would this be increased if we divided the bomb's mass over on ten (or hundred) smaller, identical bombs, and set them off so that the blast waves were in phase upon hitting the target? For some reason I don't think that's what energy efficiency truly means, so does anyone have a better word for what is actually increasing? Scientifically correct, that is. "Blast effect" sounds a bit too... Star Trekish, but if that's the word, I'll go along with it. I just need to use correct terms. Thanks! 213.161.189.107 13:31, 5 May 2006 (UTC) Hen

I think most people tend to quote payloads when talking about nuclear weapons. Isopropyl 13:56, 5 May 2006 (UTC)
I don't think it would be possible to make these mini bombs. There's a critical mass which needs to be taken into account I think. --HappyCamper 14:44, 5 May 2006 (UTC)
Don't nuclear warheads already consist of several mini-warheads that spread out - each one capable of hitting a separate target or surrounding and increasing damage on a single target? --Kainaw (talk) 14:57, 5 May 2006 (UTC)
MIRVs are one particular arrangement, whereby a missile has multiple warheads inside of it. --Fastfission 15:29, 5 May 2006 (UTC)
What you are basically arguing for is instead of having one 20 kt bomb, to instead have two hunded one ton bombs. That's obviously possible but completely defeats the entire purpose of nuclear weapons, which concentrate a large amount of energy in a very small amount of space (relatively speaking). There are, though, arrangements (again, see MIRV) where you can distribute the yields at bit — ten 300 kt bombs can do a lot more damage than one 3 Mt bomb, if they are arranged so that the borders of their blast zones are touching. See effects of nuclear explosions for more information about how increased yield results in much less damage efficiency because you are essentially increasing the volume of a very large sphere, rather than spreading out the damage along a single plane, if that makes sense. --Fastfission 15:29, 5 May 2006 (UTC)
In any case, nuclear weapons are more than destructive enough, "inefficient" or not. Extra destructive efficiency is hardly a priority; in fact, existing weapons, even, say, a 1 kiloton jobby that a first-time nuclear proliferator could construct out of reactor plutonium, are effectively too destructive to be of any use other than deterring other people from using nuclear weapons on you (or as a terrorist weapon).
What *would* be militarily useful would be a nuclear bomb that weighed 25kg, had the explosive potential of 10 or 100 tons of chemical explosive, didn't produce fallout, and whose lethal prompt radiation dose didn't extend beyond the blast radius (so everybody who would die from radiation effects is instead killed instantly by the blast). Thankfully, such a weapon doesn't appear to be possible, because the temptation to use it would be so strong I don't imagine the country that perfected the device would have been able to resist using it in their next conflict. --Robert Merkel 22:04, 7 May 2006 (UTC)
To address the "energy efficiency" question, that's something completely different than what you're asking about--it's not a question of what percentage of energy released is absorbed by the target, but rather what percentage of the theoretically possible yield is actually generated.
Nuclear weapons consist of a quantity of fissile material. You can mathematically calculate the energy which would be released if every single atom of the material underwent fission; but the actual energy released by a weapon is quite a bit less. It seems that the issue is that you have to have a minimum amount of material (the "critical mass") together to make an explosion, so a weapon has that much material, but normally kept in a configuration where it doesn't detonate--multiple pieces, or a hollow sphere, or something like that. When the weapon is set off, it pushes everything together so that a chain reaction becomes sustainable--but the energy of the explosion itself blows the material apart before the chain reaction is complete, and a significant portion of the material does not undergo fission.
In any case, it seems that the 3% figure you heard is too low for most weapons. The nuclear weapon article states "The efficiency of a fission weapon is the fraction of the fissile material that actually fissions. The maximum is ca. 25%. For Fat Man it was 14%, for Little Boy only 1.4%." Chuck 18:56, 8 May 2006 (UTC)

Extrusion of Polycarbonate[edit]

If polycarbonate is not dried before it is extruded, will the mechanical properties such as impact strength be degraded as it goes through the extrusion process. If so how large is this effect and would it be more cost effective to dry the material and extrude it or just extrude it without drying.

Censorware[edit]

The computers at my school (OS 9 iMacs) have all their internet traffic filtered at the server, so I need a method to bypass the filters? Basically, what I think I need is a proxy that does data encryption. Any suggestions?--Frenchman113 on wheels! 18:52, 5 May 2006 (UTC)

Certain sites are censored for a reason. --Chris 19:22, 5 May 2006 (UTC)
Yes, but sometimes you need to research marijuana for a reason. Is anyone gonna help or not?--Frenchman113 on wheels! 20:10, 5 May 2006 (UTC)
Do your homework and find a proxy. I've used "home13" in the past.Here7ic 20:45, 5 May 2006 (UTC)
Well, if you're really looking for marijuana info and not pr0n, you could try searching for it on Google, then clicking the cached link. That's always bypassed the blocks at my school. It doesn't give pictures, though, just text, with your search terms highlighted. Alternately, you could use [17], a proxy a friend of mine made that works reasonably well for most things. Black Carrot 21:42, 5 May 2006 (UTC)
"Certain sites are censored for a reason."
So this automatically makes it a good reason? --Bowlhover 04:33, 6 May 2006 (UTC)
Not necessarily, but it can be argued that since 1) the school is paying for the connection, and 2) it has intended it for (what it defines as) educational use, it has the right to filter content. This doesn't stop the user in question going elsewhere to access the sites s/he wants to access - at home, or in an internet cafe. — QuantumEleven 09:31, 6 May 2006 (UTC)
Why don't you talk to the school IT person? If you need to get past some filter and have a good reason, then they should be able to assist you. Otherwise, bypassing the firewall would be something that could get you into a whole heap of trouble (not just inappropriate content, but malware could slip by.) Andrewjuren(talk) 09:38, 6 May 2006 (UTC)
Well... because I'm looking for pr0n? Just kidding, I never thought of that.--Frenchman113 on wheels! 12:17, 6 May 2006 (UTC)
Sure you didn't. Did my suggestions work? If they did, and if you do decide to follow your instincts, I know another trick that might help: the Google image search is, as far as I know, pretty difficult to block. It is actually possible, in my school, to view thumbnails of hardcore porn, but not to look up the Nazi party (a real third party in America) for my AP Government report, without using a proxy. Black Carrot 16:15, 6 May 2006 (UTC)
BTW- Don't forget to set the image filter to "off". It's right below the search bar. Black Carrot 16:27, 6 May 2006 (UTC)
Personage: If you need to research mary jane, use Wikipedia, because we know almost everything about almost everything. And tell your friends to not vandalize it so you don't get banned from editing it at your school. Cernen Xanthine Katrena 14:02, 7 May 2006 (UTC)
  • If the school's censorware makes researching your homework impossible, maybe it's time to talk to the teacher who gave you that homework and have her talk to the school's IT personnel. You could also try researching using books. That would avoid all the internet censor stuff. - Mgm|(talk) 14:59, 7 May 2006 (UTC)
Argh, it's keyword based filtering! proxies aren't working on it!--Frenchman113 on wheels! 20:48, 9 May 2006 (UTC)

Water flow[edit]

I need to get a water flow of 100 liters/minute through a 12.5 mm nozzle. I will be pumping this from a 200 gallon tank at floor height through a short length of standard garden hose and out through the nozzle. I must pump this volume for a period of three minutes. I am trying to figure out what to use as a pump. I tried a standard sump pump that advertised a flow rate of 8600 gallons per hour but found my flow rate out the nozzle well short of the requirement I must meet. Do you have any suggestions? --12.19.235.34 18:58, 5 May 2006 (UTC)

When you're moving current no matter if its water or electricity, if you squeeze a large amount of it together then open it up in the direction it is going,it boosts the current. If you use a wider hose than a standard garden hose, more water will be putting pressure on your nozzle. This will increase the water pressure that is exiting your nozzle because the water has more space to move. Think of it as popping a paper bag. When you fill the bag with air it all wants out because there is too much pressure so it blows a hole in the bag. Your nozzle will act like the hole and release all the pressure. If that doesn't work you might need to consider a bigger nozzle.

Because you are looking for a short duration, you can go with a cheaper pump and a more expensive (sealed) tank. Pressurize the tank and then release the pressure through the nozzle. Then, it doesn't matter how fast the pressurizer pumps. The drawback is that you'll get a rather short period of steady pressure that dies off quickly. All in all, it is just like those super-soaker water guns. --Kainaw (talk) 19:37, 5 May 2006 (UTC)

I'm pretty sure you are talking fire-hose volumes here. Your sump pump could only do 2 gal/m or 8 L/m. City pressure at 40 psi might only get 12 L/m through a standard hose. You want another order of magnitude more than that. --Zeizmic 20:37, 5 May 2006 (UTC)

Pump are designed to deliver either a large volume of water at low pressure, a small volume of water at high pressure or some trade-off in between. When you purchase a pump it will often have a small table listing how many gallons per minute it will deliver at a certain pressure. You can estimate the pressure required at the nozzle to give you the required flow rate using the firefighters formula: gallons per minute = 29.7 x diameter in inches squared x square root of the pressure in pounds per square inch.

So you need around 14psi at the nozzle to flow 26.4gpm. That is if you are using a tapered smooth bore nozzle--if you are pumping directly out of a 1/2in pipe the pressure required will be slightly higher. You also need to take into account your "short length of standard garden hose". Trying to move 26.4gpm through a full 3/4in inside diameter hose you will have about 60psi friction loss per 100 feet of length[18]. Standard 3/4in or 5/8in garden hose will be even worse. You will need a pretty large centrifugal pump to push that amount of water through any length of small diameter hose like that. (Forgive all the non-metric units, i'm too lazy to convert them.) EricR 01:18, 6 May 2006 (UTC)

Electrical Grounding[edit]

I was wondering how it could be that a pole in the ground serves to conduct electricity to 'earth'. I mean, the concrete or soil or whatever it is that the pole is inserted into, isn't going to be electrically conductive is it? If I rectified mains electricity, and connected the negative terminal to a pole in concrete, wouldn't the pole just fill with enough electrons to eventually stop the current? --Username132 (talk) 19:49, 5 May 2006 (UTC)

You are correct. Just any old ground won't work. In 29 Palms CA, Kuwait, and Turkey, we had a hell of a time keeping ground grounded. We had to keep pouring water on it. In Turkey (since there were only 3 guys deployed), we made the ground post our pee hole. Water helps move electrons to the ground rod and keep a good supply of them ready for usage. --Kainaw (talk) 19:53, 5 May 2006 (UTC)
There's also some discussion at Ground (electricity), although it lacks the amusing anecdotes. Melchoir 20:37, 5 May 2006 (UTC)
Depending on the use, 'grounds' or poles in the ground, whatever you like to call them, are usually attached to the water piping that supplies the building which I think is copper, and anyway, grounds are generally their to serve as a better conductor than the alternative, eg you or furniture, therefore preventing fires, there use is not really to complete a circuit. Plugs generally have three prongs, the live, neutral and ground, the live and the neutral are the circuit, the ground is used if the appliance has a meatl outer casing, if through faulty wiring etc. this casing becomes live the ground/earth wire is a better conductor than you, so that should you touch the appliance you wont become the unlucky link to the earth. So however poor conductors the grounds are, as long as their better than the alternative, it doesn't matter. Philc T+C 21:47, 5 May 2006 (UTC)
And hopefully as soon as the live touches the earthed casing, it should trip the fuse or circuit breaker anyway. Typically this will require the earthing to take a number of amps, but if you have an RCD breaker then even a few tens of milliamps to earth should trip the breaker. Arbitrary username 18:23, 6 May 2006 (UTC)

Wikipedia on DVD-RW[edit]

How possible would it be to have wikipedia on a DVD-RW that was able to update itself when put into a DVD-RW drive on a computer with internet access? How long would it take to make such a thing happen if you knew how to program? When can I expect to see self-updating Wikipedia on DVD-RW? --Username132 (talk) 20:31, 5 May 2006 (UTC)

On a DVD-RW would technically be possible, but not advisable given the limited amount of times it can be rewritten. But if you really wanted it'd be a pretty easy task. In fact, it might be possible with hardly programming anything since the sourcecode to wikimedia is available and so is the database which holds the articles. Basically you could run a webserver with php support and a database engine from the DVD-RW and you're done. - Dammit 20:52, 5 May 2006 (UTC)
Note that, depending on what you want on your DVD, the amount of content on Wikipedia may be too big to fit on one disk. For instance, including all the images is an extra 76GB. Read all about it at Wikipedia:Database download. — QuantumEleven 09:27, 6 May 2006 (UTC)

Time consistancy theory??[edit]

What is the name of the space-time theory where all three time-periods (Past, Present, and Future) are all occuring at the same time? That is to say, as I sit typing this, I also sit thinking it up, and sit drinking my coke after submitting. Thanks! Here7ic 20:41, 5 May 2006 (UTC)

Well I don't suppose you're talking about Multiple World? If so, that wouldn't really be a fitting description. But then again it really doesn't sound like MW. I'll be waiting for a better answer, this sounds interesting. :)
I doubt there's a scientific answer. God is often said to exist outside of time, so a deity might experience all times at once. In the philosophy of space and time, an idea that resembles your question is called eternalism. See this and its subarticles for more. Melchoir 21:43, 5 May 2006 (UTC)
This is the Everett many-worlds_interpretation, or consciousness causes collapse that you are looking for, or maybe the Copenhagen interpretation. -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 00:38, 6 May 2006 (UTC)
You're definitely thinking of Time Cube. —Keenan Pepper 00:44, 6 May 2006 (UTC)
Ah, the time cube... Isopropyl 15:36, 6 May 2006 (UTC)
In special relativity, the time-ordering of events can depend on the reference frame that you're in, for events which occur far enough apart in space that you would have to travel faster than light to get from one to the other (known as a "space-like" interval). But the three events you describe are all in the same place (separated by "time-like" intervals), so the time-ordering is the same in all reference frames, and anything that says otherwise is probably sci-fi. See special relativity#Causality. Arbitrary username 15:43, 6 May 2006 (UTC)
I don't know if this is what you're getting at, but in a near-death experience, the past and present may become a single landscape of events. —Pengo 05:10, 10 May 2006 (UTC)

Nucleus and cytoplasm[edit]

This is probably a very simple question, but it occurred to me while doing some reading today. We know that one can remove the nucleus from one cell and replace the nucleus in another cell (somatic cell nuclear transfer) and it will (if you are lucky) develop normally. Does this work if the two cells are from different species? I imagine it would not work between animals and plants since their cells contain different organelles, but what about animals with high degrees of relatedness (i.e. a chimpanzee and a human)? Has anything like this been attempted (I assume not with humans, of course, but dog/wolf wouldn't surprise me if it had)? If not, should it work? --Fastfission 22:36, 5 May 2006 (UTC)

Note the last sentence in the somatic cell nuclear transfer article: "Not all of the donor cell's genetic information is transferred. DNA of organelles (mostly mitochondria) is left behind, with the resulting cells retaining those structures which originally belonged to the egg." I think this would be the main factor that determines if it will work cross species, the mitochondrial DNA would have to be compatible for it to be possible. I'm not a biologist though, so it's only a guess. - Dammit 23:57, 5 May 2006 (UTC)
That's a good question. I suspect not, but for very closely related species I can't be absolutely certain. I'll also note that SCNT is extremely traumatic for cells even when you're working in the same species.
Note that if it did work, the effect would 'wear off' as the host cell would start synthesizing proteins as specified by the transplanted nucleus. After a cell division or two you'd be hard-pressed to find any trace of the original host; all of the proteins present would be those specified by the transplanted nucleus' DNA.
The exception would be in the mitochondria, as mitochondria have their own DNA that's replicated and handled separately from the genomic DNA in the nucleus. In principle I suppose that you could have a human cell with chimpanzee mitochondria, say. To achieve that end result, it might be easier to transfer mitochondria than to swap nuclei, however. TenOfAllTrades(talk) 00:06, 6 May 2006 (UTC)
That's an interesting thought about it. I was reading about theories of cytoplasmic inheritance (which is surprisingly red-linked) which is what got me thinking about this. --Fastfission 00:36, 6 May 2006 (UTC)
It does work and it is already being experimented with to see if it can be a viable method of increasing the populations of endangered species. See somatic+cell+nuclear+transfer+interspecies. Dragons flight 02:30, 6 May 2006 (UTC)
It can work, and even if it does, it'll definitely have some problems associated with it. Isopropyl 04:39, 6 May 2006 (UTC)

Yellow ants[edit]

Are there such things as yellow ants? Sort of translucent like honey? --HappyCamper 22:40, 5 May 2006 (UTC)

Sure. They're called termites. GeeJo (t)(c) • 23:45, 5 May 2006 (UTC)

May 6[edit]

Fear-induced incontinence[edit]

Though it seems to happen often enough in movies and is commonly used as an expression, is it plausible that a large segment of the human population would react to extreme fear by experiencing incontinence (either fecal or urinary). My understanding is that strong anxiety makes it dificult to urinate, so if anything, people who are scared should find it near impossible to urinate, and not the other way around (I assume the same rules apply to defecation). To be blunt, which is the more plausible outcome, being "scared shitless", or "shitting your pants"? --Aramգուտանգ 03:46, 6 May 2006 (UTC)

Funny how in "24", they never go to the bathroom... Anyway, strong anxiety can certainly take your mind off going to the loo, and this, I would say, is more likely than being scared so much that you actually piss yourself unintentionally. It sounds like a climbing ladder, and the first is more frequent than the other. I mean, you'd have to be REALLY scared, shock-scared, to immediately shit your pants. Either that, or go a long, long time in controlled anxiety.
What do you mean - in 24, they go to the bathroom the same time as we do - during the ads! -- Chuq 07:12, 7 May 2006 (UTC)
I couldn't say, but your last sentence is mistaken. Being "scared shitless" (which, incidentally, redirects to fight or flight response) means you no longer contain any, as it's all migrated downwards. Strong anxiety does make it difficult to pee in a public restroom (if that's what you mean), but my experience is that that's performance anxiety, and as such, stands in the way of action of any kind. Mortal terror, which is what it's supposed to be connected to, is rarely experienced in a bathroom outside of psycho-thrillers. I don't know how people really respond to extreme fear, having never seen it happen, but if it helps, the rationale I've heard for why it happens in animals (assuming it does) is that to run as quickly as possible, they have to lose as much excess weight as possible. Black Carrot 16:09, 6 May 2006 (UTC)

I'm guessing the defecation and urination fear response is a protection mechanism against predators. That is, once you do that, you no longer smell like food to the predator, so it might let you go. Our instincts might be sufficiently vague that any extreme fear causes this, however, not just predators. I recall a nice pick of a bungee jumper with an impressive brown streak up the back of his shirt (he was upside down, of course, when this happened). StuRat 22:01, 6 May 2006 (UTC)

I don't know for certain about extreme fear (though I have no reason to doubt that it's a real response), but severe trauma can definitely causes incontinence of both types. --Ginkgo100 23:04, 6 May 2006 (UTC)

Well, the losing weight and predator repulsion explanations make sense, but what I'm really wondering about is whether people actually piss/shit their pants when they're scared in real life. Since paruresis is caused by anxiety, it doesn't matter if it's anxiety caused by fear, or performance anxiety. Are there any documented cases of people experiencing incontinence when scared, where fear is the only cause for it, i.e. they haven't been holding it in for a long time, or they haven't found themselves suddenly to be in freefall. Also, is there a term for it that's better than "fear-induced incontinence", because this is a difficult subject to search for without key terms. --Aramգուտանգ 00:45, 7 May 2006 (UTC)

I can assert, through personal experience, that a person in imminent danger of drowning (surely, a situation involving real fear) can defecate involuntarily. It happened to my daughter, then 13, before I and my brother-in-law rescued her.G N Frykman 17:43, 8 May 2006 (UTC)

Interesting. When I was a kid and almost drowned (caught in rip tide), I found it very peaceful and no incontinence was involved. Apparently near death experiences vary widely. StuRat 17:07, 12 May 2006 (UTC)

I remember reading something that said something along the lines of when your body is experiencing extreme (performance, assumedly) anxiety, it does not want to bother with many less-important processes such as digestion, and so it simply voids the body so it can focus on immediate survival. Sounds very plausible to me. --T. S. Rice 03:28, 13 May 2006 (UTC)

The Neutral Wire.[edit]

The 3 wires that run to my house from the power lines are two hot and one neutral wire. The ground wires in my home electrical system are connected literaly to the earth via a ground rod which runs a certain number of feet into the ground. My questions refers to the neutral wire. When I plug a lamp into an outlet, the AC voltage moves back and forth 60 times per second, and electrons flow back and forth through my lightbulb giving up their energy as light and heat, and in turn this voltage is running through the neutral wire as well - does it run all the way back to the power station? Is it connected to a huge ground rod? Why can't I just use my ground as a 'neutral' wire? Aren't some neutral wires actually attached to the ground buss in the panel? (Not in Canada)

If anyone can help me understand this, I'd appreciate it.

CW

60.241.30.237 06:44, 6 May 2006 (UTC)

I wish I could give you a better answer, but I do know that the electrons in your wiring actually move very slowly, only a few meters per second and not nearly the speed of light as many people believe. Furthermore, although your ground at home may act okay as a neutral sink for electrons, I think that most houses don't have good enough ground to act as the "neutral" wire. Additionally, it would cause pretty nasty shock if you were to walk by it, not to mention potential radio noise. I would recommend reading our article on Electric power transmission, and related "See also" articles. Andrewjuren(talk) 08:48, 6 May 2006 (UTC)
Yes, it runs all the way back to the power station via the earth. There is so much mass of "earth" that it forms a very good conductor. Although you can connect an electrical circuit directly to earth, this is not a good idea as you need a very good, deep, solid connection. This is precisely what the supply company provides with their "neutral". I suggest you read our article on ground and neutral. --Shantavira 09:03, 6 May 2006 (UTC)
Yep, that's true, but just a point of note, that your power company probably provides three-phase electric power. Although each individual household will generally just be on one phase, the current that you (and others on the same phase as you) draw from the live cable approximately balances out with other households that are on the other phases, so the amount of current that actually has to run back down the neutral all the way to the power station is much less than you'd first think. Arbitrary username 15:52, 6 May 2006 (UTC)
The nuetral wire and live wire connect to the Generator, the earth wire is for safety. In the UK ans such countires, where laying vast amounts of power lines is not a problem, because the country is no that big, the current is not returned to the powerstation via the ground, which is done in some countries, it just goes back down the nuetral wire and completes the circuit. Philc T+C 09:18, 7 May 2006 (UTC)

Fat absorption[edit]

I've seen a few books and web sites out there that say that the humans cannot absorb more than 10 grams per hour of fat from the GI tract. Where does this come from, and what type of experiment (if any) was done to determine this? Experiments which I have undertaken on myself seem to suggest otherwise. -User: Nightvid(unregistered)

Well, it takes bile to break down fats into a form that can be absorbed, and this takes time, and, of course, bile. That rate doesn't seem all that slow to me; if food stays in the proper portion of your digestive system for a day, that's some 240 grams you can absorb each day. Since there are 9 calories per gram of fat, that makes 2160 calories per day from fat. That's plenty of calories per day, even if you don't eat any protein or carbs or consume any alcohol. I suppose any undigested fats which leaves the system would cause diarrhea, however. StuRat 21:50, 6 May 2006 (UTC)

Why is yawning contagious between different species?[edit]

I yawn, my parrot yawns. My parrot yawns, I yawn. I see a dog in the street yawning, I yawn. I yawn near my mother's cat, my mother's cat yawns.

etc.

Why can a yawn be transferred from species to species like this? I've read the yawn article and it mentions that it can be 'interspecific' in it's contagion but it doesn't explain why. Anyone know? Thanks.

This is from my shaky memory, so I can't guarantee 100% accuracy, but ISTR that t's a survival mechanism. Yawning is a way of increasing the oxygen uptake in the body. As such, it also aids alertness by increasing the oxygen getting to the brain. It makes sense that if one person/creature yawns then either (a) the oxygen level may have dropped slightly, or (b) there is some need for the person/creature to be alert. In both cases, it would be a good survival heuristic for other nearby people/creatures to also yawn. It's not a conscious decision to yawn in these instances; it's a natural response to the surroundings ("surroundings" in this case also including other nearby animals/people). As with other good survival heuristics, they tend to increase the chances of an individual's survival and... well, see evolution if you want to take that train any further. Grutness...wha? 13:34, 6 May 2006 (UTC)


There was an episode of Mythbusters about yawn contagion.--Sonjaaa 13:51, 6 May 2006 (UTC)

No, yawn says, "A long-standing hypothesis is that yawning is caused by an excess of carbon dioxide and lack of oxygen in the blood. The brain stem detects this and triggers the yawn reflex. The mouth stretches wide and the lungs inhale deeply, bringing oxygen into the lungs and hence to the bloodstream. It is almost certain however, that this hypothesis is not correct. One study..." Black Carrot 14:55, 6 May 2006 (UTC)
I can't even read this question without yawning. --Ginkgo100 23:07, 6 May 2006 (UTC)
When you end up thinking about yawning, you almost want to yawn. --Mac Davis 01:44, 7 May 2006 (UTC).

The consensus among people whos study this stuff seems to be that yawning really is contagious. A reasonable explanation, it seems to me, would be mirror neurons, neurons that respond to behaviors observed in others by performing exactly the same. (This explains why you wince also when another person steps on a thumbtack. However, the first Google result for "yawning contagoius" claims that a 2005 study using fMRIs found that the mirror neuron system was inactive when viewing videos of other people yawning. That would seem to indicate that some other system is at work, though probably still one that does depend on some degree of social and self-awareness as humans and chimps are the only species believed to exhibit contagoius yawning. If you want a slightly longer answer without having to wade through the scientific articles, you might want see this guy's blog. BTW, the result of that Mythbusters segment was "CONFIRMED," if you were wondering. -Wiccan Quagga 05:09, 7 May 2006 (UTC)

Immunity to self-produced toxins[edit]

Well, this may be a stupid question, but as the saying goes... How is it that animals who produce toxins are typically immune to them? I understand how, from an evolutionary POV, it's obviously beneficial for an animal not to be susceptible to its own species' toxins, but I was wondering how this is typically accomplished. How are scorpions who secrete neurotoxins not affected by them, for example? Do they have substances in their blood which break down the specific neurotoxin they use before it can harm them, or do they actually have a biological makeup which renders the neurotoxin ineffective? Are all animals who are broadly venomous to other species immune to their own toxins? 82.92.119.11 09:29, 6 May 2006 (UTC)

To answer your latter question, no. Your own example of the scorpions is a good example of that. On nature channels they often show two scorpions fighting, resulting in the death of one. Their protection against the venom is their exoskeleton. - Dammit 09:37, 6 May 2006 (UTC)
Our own scorpion article states "the belief that scorpions commit suicide by stinging themselves to death when surrounded by fire is of considerable antiquity and is often prevalent where these animals exist. It is nevertheless untrue, since the venom has no effect on the scorpion itself, nor on any member of the same species (unless the venom is injected directly into the scorpion's nerve ganglion)." This doesn't seem to imply the exoskeleton is what renders the venom ineffective, since otherwise the "same species" mention is peculiar. The article doesn't seem to be saying that the venom is ineffective because the stingers can't penetrate the exoskeleton (although it does say that if the toxin where to reach the ganglion directly somehow, it would be effective). Is the artticle wrong or simply misleading? 82.92.119.11 09:58, 6 May 2006 (UTC)
Hmm, I'm probably wrong then. It could be that the fights I saw on tv where different species (I recalled it from memory, havent actually seen one recently). - Dammit 11:23, 6 May 2006 (UTC)
I was just wondering.. What would happen if a King Cobra's venom was injected into another King Cobra? Jayant,17 Years, Indiacontribs 09:42, 6 May 2006 (UTC)
Well, shellfish are immune to shellfish poisoning because their sodium channels bind STX much weaker than most species. Same thing with TTX and the pufferfish. Dr Zak 14:23, 6 May 2006 (UTC)
I guess that it is quite common for poisonous animals to have better resitance against their own poison since that sounds to me like a quite obvious useful trait. ALso regular contact to the poison produced by the own body should produce antibodies. But that doesn't mean that all species are totally immune or even have better protection against the poison than animals in general. These are just my own guesses based on general knowledge about animals. Jeltz talk 16:22, 6 May 2006 (UTC)
Interesting. Apparently the cobra (and the mongoose) has its acetyl choline receptors at the neuromuscular junction "shielded" from the effect of the neurotoxin, by a genetically determined sugar complex overlying the binding sites. The normal ACh can "get through the holes" in this shield and still cause normal muscle contraction. The resistance that the elapids have to their own venom is thus not a function of their immune system as such. In contrast, the viperidae have circulating antibodies which neutralise their proteolytic venom, and their tissues lose their resistance in the absence of their serum. The pufferfish's immunity is based on the substitution of a single amino acid in the sodium channel protein. Japanese sushi chefs are trained and licensed to try to reduce the incidence of TTX poisoning, and they are required to eat the pufferfish dish that they have prepared as part of the exam. --Seejyb 20:53, 6 May 2006 (UTC)
So it appears that all mechanisms occur in practice: "active" immunity through antibodies and "passive" immunity by a change in regular makeup which renders the toxin ineffective. I'd also half expect some species to have no immunity to their own poison, but it would take an unusual set of circumstances for this not to be a huge drawback (as other members of your species would likely compete with you over territory/food/mates and casualties would be very high). 82.92.119.11 21:52, 6 May 2006 (UTC)
Actually some poisonous species fight among each other, and are vulnerable to each other's poisons. The difference is that the gland producing the venom is usually carefully contained within a thick layer of lipids so as not to have it escape to the bloodstream. However, when used against another organism, usually it is injected through fangs, which pierce skin, and any lipids, or similar protection on another species. If you were to pierce the venal glands of another species, that species may die. Of course, additional protections and immunities may protect that. Elle vécut heureuse à jamais (Be eudaimonic!) 23:55, 6 May 2006 (UTC)
Note the difference between venom and poison. Poison is distributed throughout, or in large areas of, an animal's body, whereas venom is produced, stored and delivered in a specific set of organs and not distributed in other tissues. A poisonous animal needs to be immune to its own poison, but not so for a venomous one. —Pengo 05:22, 10 May 2006 (UTC)

The Perfect Crime[edit]

Supposing you had to off a someone who happened to be an insulin-dependant diabetic, preferably without getting caught. What if you were able to remove the insulin from one bottle and replace it with a glucose solution, put the spare bottle in the microwave and then replaced them both where you found them. How long would it take for the glucose to have its effect, and would it be fully lethal? Obviously you'd need to dispose of the glucose-containing bottle, wash out the syringe, maybe take up some denatured insulin into the syringe and perhaps wipe the point of injection with some damp cottonwool to remove and traces of glucose. What would be left for forensics? They'd check his blood sugar and it'd be through the roof... would this look suspicious? How about if the glucose solution also contained some alcohol... would they check stomach contents? --Username132 (talk) 11:14, 6 May 2006 (UTC)

If you're gonna commit a crime, don't talk about it on a public website... I pray for the human race.--Frenchman113 on wheels! 12:14, 6 May 2006 (UTC)
Maybe you should stop trying to kill people and write scripts for CSI.--Sonjaaa 13:50, 6 May 2006 (UTC)
I think it is important to point out there is little or no forensic evidence in most cases (even murders). Life is not like CSI. --66.168.20.7 14:08, 6 May 2006 (UTC)
You were asking how long it would take for the glucose to take effect. Leaving aside the rather gruesome and distasteful nature of your post, if you do a first aid course you get to learn that hypoglycemia (caused by too much insulin and/or not enough food for the amount of physical exercise) can have a very rapid onset, but that hyperglycemia, although potentially just as serious, is a condition with slow onset over many days. Arbitrary username 15:59, 6 May 2006 (UTC)
I think a diabetic would probably notice very quickly if their insulin wasn't having an effect. And I don't think hyperglycemia would kill someone before they could get help. Besides, everyone knows the best way is to whack someone on the head with a frozen loaf of bread, thaw it, and feed it to your dog. --BluePlatypus 19:52, 6 May 2006 (UTC)
Sharpen a thick icicle and jam it hard into your victim's neck. Twist and pull. Throw icicle into a hot bath. Sorted. :) --Kurt Shaped Box 21:42, 6 May 2006 (UTC)
There would be blood in the drain. CSI would bring a shark to sniff it out. -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 02:56, 7 May 2006 (UTC)
Your idea doesnt come close to working for a variety of reasons. Removing the insulin and filling the bottle with glucose would be equivalent to delaying or skipping an insulin shot and then taking a sip of regular soda. Hardly a recipe for sudden death-- people with diabetes do this all the time. alteripse 22:10, 6 May 2006 (UTC)
  • And apart from what Alteripse mentioned, getting the syringe and insulin would almost certainly involve leaving trace evidence of some kind even if you were careful to get rid of foot- and fingerprints. If you've been on a crimescene, you always leave something behind. - Mgm|(talk) 14:16, 7 May 2006 (UTC)

Effect of wrong phasing (3-phase supply) connection to the UPS[edit]

I would like to know the effect of connecting the wrong phasing power supply to the UPS in the telecommunication base station. Explaination with diagram would be very helpful. Thank you

Perhaps you could improve your question; I don't understand your question and it doesn't seem as if anyone else has either. What is "the wrong phasing power supply" and which "telecommunications base station" are you referring to? Andrewjuren(talk) 07:09, 7 May 2006 (UTC)
Does our article on three-phase electric power answer your question? If you mess with three-phase supplies one danger is that you'll end up applying 415volts instead of 240volts. --Shantavira 07:25, 7 May 2006 (UTC)

I think his question was about wrong phase sequence. That is, what happens if one connects RBY to terminals marked RYB (R-R,B-Y,Y-B instead of R-R,B-B,Y-Y) of an UPS (doesn't matter were the UPS is used) -- Wikicheng 08:42, 8 May 2006 (UTC)

Yes, Wikicheng is correct-what is the effect if the supply connected to the UPS is in the wrong phase sequence RBY instead of RYB.

Depends entirely on the design of the UPS, In a simple offline or double conversion online type it would most likely make no difference. In types that work by adding to/subtracting from the voltage as it passes through it could well cause big problems if the UPS wasn't designed for the eventuality. If you are installing a UPS in a situation where phase reversal is a real possibility (e.g. a mobile unit in a country where sockets are often wired with wrong phase order) i'd strongly advise contacting the manufacturer first. Plugwash 20:54, 13 May 2006 (UTC)

Pearson Correlation[edit]

Would it be correct to say (as a general conclusion for relationships among correlations/ Pearson correlation) that if X is related to Y and Y is related do Z, that this necessarily means that X is related to Z? -- 4.155.249.93 17:04, 6 May 2006 (UTC)

No, correlation is not transitive. Consider f(x) = Sin(x), g(x) = Cos(x), and h(x) = Sin(x)+Cos(x). h(x) is partially correlated to both f and g, but f and g are uncorrelated to each other. Dragons flight 17:59, 6 May 2006 (UTC)
And you can easily extend this to a situation where f and g are actually partially anticorrelated, while h is still partially correlated to both f and g. Just consider f(x) = Sin(x), g(x) = Sin(x+2pi/3), h(x) = Sin(x+pi/3). Arbitrary username 18:04, 6 May 2006 (UTC)

modern communications technology[edit]

I would be interested in a recap or summary of the latest communications technology that includes such devices as the internet, telephone linkages, digital photography etc., and what these actually do in the real world. Thank you

Read these articles! internet, telephone, digital photography. Try using the little search box on the side to find other articles that interest you. Andrewjuren(talk) 01:34, 7 May 2006 (UTC)

confusion with Schrodinger's equation[edit]

Obviously, we all know that solutions to Schrodinger's equation is called wave functions. In convention, we call "a one-electron wave-function" a orbital. NOW, if orbital is essentially a mathematical description of the behavior of one electron, then why on every orbital we can have 2 electron filled up?

Thanks

Strictly speaking, you have to solve Schrodinger's equation for the system you have (e.g. an atom with multiple electrons). However, to an approximation you can use the solution of Schrodinger's equation for one electron (hydrogen atom) when considering the forms of the atomic orbitals in more complex atoms, provided that you take into account certain rules about how electrons behave. A key consideration is that electrons are so-called fermions, which means they obey the exclusion principle, that is the property that no two electrons can share the same set of quantum numbers. Each atomic orbital is described by a set of quantum numbers, but electrons have an additional quantum number, so-called spin quantum number, which for an electron can take two possible values (1/2 or -1/2). This means that a maximum of two electrons can share the same atomic orbital without violating the exclusion principle. Arbitrary username 17:53, 6 May 2006 (UTC)
You don't have to make the approximation of using hydrogen orbitals. - You still can describe the total wave-function in terms of single-electron orbitals. They're just different from the hydrogen ones (and can't be solved analytically). However: When you solve the Schrödinger equation for a two-or-more-electron system, you can't just solve the thing, because of the aformentioned exclusion principle. What this means is that the wave equation must also be antisymmetric with respect to the exchange of two electrons. Not just any solution is valid, in other words. Once you satisfy that condition, (for instance using a Slater determinant) then you can have two electrons with opposite spin in the same spatial orbital. Note that your resulting wavefunction is no longer a simple product of one-electron orbitals, but a rather large linear combination of them. But they're still one-electron orbitals. --BluePlatypus 19:29, 6 May 2006 (UTC)

Do people in comas dream?[edit]

I am curious about this. My guess is that they do. But it may depend, which is why I am asking. Thank you--ĶĩřβȳŤįɱéØ 18:40, 6 May 2006 (UTC)

We don't know. --Mac Davis 01:43, 7 May 2006 (UTC)
Somebody must know. Surely people who've come out of comas have been asked what they experienced, and whether or not they dreamed. JackofOz 02:25, 7 May 2006 (UTC)
If they say yes we have the answer, but if they say no we don't, because even during normal sleep people don't always remember their dreams. --Ginkgo100 03:01, 7 May 2006 (UTC)
That's fine. But all it takes is one ex-coma person to remember they were dreaming at some stage, and that proves it can happen. And surely coma patients have been monitored to detect evidence of REM. Is MacDavis saying no REM activity has ever been detected in a coma patient? JackofOz 03:12, 7 May 2006 (UTC)
I don't think that's true. What if the person has dreamt in a normal sleep just after he's come out of the coma? How would ey know? – b_jonas 13:00, 7 May 2006 (UTC)
So, no actual facts are available? Black Carrot 03:12, 8 May 2006 (UTC)
I think the real question is whether people in comas experience REM sleep, since it is during REM that we dream. Unfortunately, I don't know the answer to that question. --Ginkgo100 15:54, 8 May 2006 (UTC)

Helicopter and Car[edit]

A 5500kg helicopter accelerates upward at 0.50m/s² while lifting a 1200kg car. What is the lift force exerted by the air on the rotors? What is the tension in the cable that connects the car to the helicopter?

I drew my free body diagram and this is what I got for the two equations:

Helicopter

ΣFy = ma
 FA - FG1 - T2 = m1a

Car

 ΣFy = ma
 T1 - FG2 = m2a

FG1 being 9.81 x 5500, T2 being 0.5x 1200, T1 being 0.5 x 5500, FG2 being 0.5 x 1200

My problems lies here. I need something to cancel out so I can solve for FA or T, but nothing cancels out. T1 and FA are the same the force, and so are FG2 and T2, and I've tried going FA - FG (total) = m1a and FA - FG2 = m2a but I that didn't give me the right answer either. I think my problem may lie in the fact that I have acceleration as FA. I've noticed that in some questions that we have done that acceleration is sometimes FA, and sometimes isn't included at all on that side of the equation. Anyone know why? Now as I think about it I don't even know why I have a T1 and T2 and not just T... I am really unsure here. Thanks. C-c-c-c 19:34, 6 May 2006 (UTC)

Hi, I'll have a proper think about this and post again soon, but as a quick comment you should definitely just have a T (if we can neglect the mass of the cable itself) -- see Newton's third law. Arbitrary username 20:30, 6 May 2006 (UTC)
Maybe I should just clarify what I mean by appealing to Newton's third law here. I mean that the two tensions will also act on the cable. If we assume the cable is very light, then if there was any significant difference between T1 and T2 it would lead to a huge acceleration of the cable. Hence we can treat it that T1=T2. Arbitrary username 21:21, 6 May 2006 (UTC)

Okay, problem seems to be firstly that you've got these two different tensions, and then made some unfounded assumptions about what they should be equal to. Just set them both to T, and then solve for FA by adding the two equations:

FA - FG1 - FG2 = m1a + m2a

or as I'd prefer to write it,

FA = (m1 + m2)(a + g)

That gives you FA, which (no surprises) is enough to counteract gravity and provide the upward acceleration, for the combination of helicopter plus car.

Also you have

T = m2 (a + g)

In fact it's an important result that an upward acceleration and a gravitational field have an equivalent effect, so the a+g in the answers is no surprise.

I'll leave you to put the numbers in.

Arbitrary username 20:43, 6 May 2006 (UTC)

Thank you so much! I just have one more question related to this, you said that all you have to do is add the two equations and I was always told I should subtract them. Your method does give the right answer, so does it work either way? Also when you're subtracting, wouldn't it matter which order you put in your equations (eg. 2 - 5 = -3, 5-2 = 3). This gives you the same number, but negative, so could it just be giving it in the opposite direction? Thanks a lot again. C-c-c-c 20:53, 6 May 2006 (UTC)
Think about what you're doing when you "add" or "subtract" equations. You can do anything to the left side of an equation that is numerically equivalent to what you do to the right side. For example, adding terms to each side which are known to be equal because of another equation that you have. Or subtracting them. Which you actually do will depend on what terms you are trying to eliminate. Arbitrary username 21:21, 6 May 2006 (UTC)
Oh, I see now. I thought it was one either one or other, and there wasn't choice between adding or subtracting. Thanks a bunch. C-c-c-c 21:31, 6 May 2006 (UTC)

Identification of stars as distant suns[edit]

My question: when did we start "knowing" that the stars in the night skys are actually very distant stars? The star article itself is severely lacking in the cultural and historical prospect... Anyway after a bit of searching now I know there was this Nicholas of Cusa who proposed that stars are suns, though obviously he would not be able to "prove" his claim. However nowadays everyone regards this idea as a fact. So when and how people "prove" that stars are in fact suns very far away but not lamps embedded on the celestial sphere? Thanks! --Lorenzarius 19:48, 6 May 2006 (UTC)

The idea of extrasolar planets is more modern, but I believe Archimedes was able to prove that stars were distant objects, or even earlier, I think. It would be plausible for the Babylonians or the Egyptians to have known it. (Let me check a few articles). Simple trigonometry was used based on measuring the changes in distance over different positions. Naturally an extremely large distance would mean miniscule changes in perspective. Elle vécut heureuse à jamais (Be eudaimonic!) 22:32, 6 May 2006 (UTC)
Yup, with the method of parallex we would be able to notice minute movement against the stellar background of some very close stars. Ancient people would also know that the stars are more distant than the Moon, Jupiter, Saturn etc because they could observe the eclipse of stars by those solar system objects.
But perhaps let me rephrase my question: how did we know that the Sun is just one of the stars, and that the distant stars are the same thing as the Sun? --Lorenzarius 23:13, 6 May 2006 (UTC)
Actually the idea is fairly modern, with the invention of mass spectrometry did we "prove" that our sun was like other stars (or vice versa) - full of hydrogen, though differing in mass. The hypothesis was probably earlier, but it is my guess it wouldn't be more than 100-200 years before the mass spectrometer's invention, because the article at astronomy says that the idea that the sun was like other stars was fairly recent. Elle vécut heureuse à jamais (Be eudaimonic!) 23:15, 6 May 2006 (UTC)
Ordinary spectroscopy in the visual spectrum, not mass spectroscopy. Mass spectroscopy would require a sample. Which I think it's safe to say we don't have. --BluePlatypus 00:49, 7 May 2006 (UTC)
We didn't have a sample until the Genesis spacecraft. Dr Zak 01:24, 7 May 2006 (UTC)
It's spelled parallax. —Keenan Pepper 04:06, 7 May 2006 (UTC)

carbon dioxide[edit]

Is it considered a fact that the majority of trees over 30yrs of age produce more carbon dioxide than oxygen? 60.226.90.64 22:05, 6 May 2006 (UTC) JAG.

Hardly. If they did so, it meant they would consume more food than they were producing (photosynthesis), and would eventually run out of food. Besides, the aging of trees varies based on species, so I don't think the 30 year limit would be absolute. Elle vécut heureuse à jamais (Be eudaimonic!) 22:33, 6 May 2006 (UTC)
Well, it's true once they die and start decaying. Is that what you meant? --BluePlatypus 22:45, 6 May 2006 (UTC)
I think the petitioner wants to know more about photorespiration. Dr Zak 01:26, 7 May 2006 (UTC)

Nitrogen through breathing[edit]

The article "Breath" says that we inhale and exhale the same amounts of Nitrogen, about 78%. Obviously, at least to me, we're not absorbing it. Does this demand a natural defense mechanism, or is it rather the lack of anything for the nitrogen to bond to? (Mixed answers are thus fairly acceptable) THANKS! This is such an amazing resource, and that's just the articles on their own.

It is simply diffusion, or osmosis (sort of). There are little processes that consume nitrogen, so the nitrogen content in the bloodstream and the nitrogen breathed in is the same. There is exchange, but they are the same type of molecules, so the net diffusion rate is zero, though nitrogen molecules diffuse through the membrane of the air sacs at all times. Oxygen diffuses in because the oxygen content in breath is higher than that of the bloodstream (and is further attracted to haemoglobin), and carbon dioxide diffuses out because carbon dioxide content in the bloodstream is greater than that in the lungs. Nitrogen does get absorbed if the nitrogen content in the air is greater than that in the bloodstream...when you do deep water diving one risks getting decompression sickness too easily because the nitrogen has been pressurised and sudden retrieval upwards causes it to burst...then there's the opposite with nitrogen narcosis. Elle vécut heureuse à jamais (Be eudaimonic!) 23:51, 6 May 2006 (UTC)
Well, if there was something for it to bind to, we'd absorb it. I'm pretty sure that the body does not have anything which specifically binds nitrogen gas molecules as with O2 and hemoglobin. We don't have any use for it. Although there are bacteria which use nitrogen gas. (nitrification bacteria) As pointed out above, nitrogen gas (like all gasses, to different extents) does dissolve in water. Since the nitrogen dissolved in your body is in equillibrium with the nitrogen in air, you get the same amount going in and out. What happens in decompression sickness is that that equillibrium is disturbed, since more gas (again, like all) will dissolve into in your body at higher pressure. So if you suddenly drop the pressure, the nitrogen will evaporate into bubbles, which is very dangerous. It's the exact same thing that happens when you open a can of soda. Once the soda has gone flat, it's reached equillibrium with room pressure. So it's not about the concentration. Just the pressure. --BluePlatypus 01:00, 7 May 2006 (UTC)
The dinitrogen molecule is extermely inert in the absence of a catalyst. Only a few bacteria have evolved the ability to reduce nitrogen from the air to ammonia and use is in their metabolism. Wikipedia has an article on nitrogen fixation, unfortunately it's not very good at the moment.
At normal air pressures nitrogen is not an issue, but when breathing compressed air (as when SCUBA diving), the high partial pressure of nitrogen can lead to nitrogen narcosis and, if ascent is too fast, decompression sickness (the bends). (Actually, reading the article on DCS, looks like nitrogen alone is not to blame, if you want to quibble.) --Ginkgo100 03:19, 7 May 2006 (UTC)
Nitrogen goes into the lungs, is dissolved into the blood stream, body fluids and cells in proportion to it's partial pressure, However, even though the nitrogen molecules are floating about in all these fluids (everywhere - eye to big toe - at the same partial pressure) the body does not do anything with it, i.e. does not utilise it in any chemical reaction, nor does the body produce any N2 by any chemical process, nor does the N2 molecule take part in any unwanted chemical reactions (no defences needed). Therefore, at a constant pressure, the nitrogen that you breathe out is the same as what you breathe in - no nitrogen added or taken away or changed. Your conclusion, though mainly correct, is based on figures for dry gas. In reality the air you breathe out contains approximately 6% (approx 6 kPa) water vapour (at sea level and body temperature), so that the percentages given in the article are not true for the air coming out of your mouth or nose. I shall see if I can adapt the article, while still pointing out what you deduced. --Seejyb 23:32, 7 May 2006 (UTC)

May 7[edit]

Difference in Time[edit]

What is the difference in time during the existance of the universe as we know it today and since the Big Bang and anytime prior to the Big Bang? -- PCE 00:22, 7 May 2006 (UTC)

See Big Bang.-- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 01:42, 7 May 2006 (UTC)
Age of the universe claims that the universe is about 13.7 billion years old. Before the Big Bang, time is believed to have not existed. Andrewjuren(talk) 01:44, 7 May 2006 (UTC)
Ahem, time is not known to have existed, not necessarily didn't exist. -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 02:48, 7 May 2006 (UTC)
There are many a misconceptions about the big bang caused by popularization. The big bang was not the so called, beginning of the universe/time. It was only a time period in which spacetime started to expand— for unknown reasons. Everything was still there before the big bang, the big bang was not a moment of creation either.-- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ.
The Big Bang model goes to 10e-43 seconds. As far as most people are concerned, that's close enough to the beginning of the universe. I am fully aware that the stuff that happens before is "important", but to my knowledge there is no model which has general scientific consensus. So, I guess to correctly answer PCE's question: 13 billion years since the Big Bang and there were 10e-43 seconds before the Big bang. Andrewjuren(talk) 07:03, 7 May 2006 (UTC)
Sorry, I didn't mean to "condemn" your answer or anything, it was just fine, and you are right. But I do not agree with you impling that the big bang was the beginning of time and/or the universe. -- User:Mac_Davis (unlogged in) 11:40, 7 May 2006 (UTC)
Do you have a citation for that? The Stephen Hawking article seems to indicate that Hawking believes there was no "time before the big bang": "Asked in October 2005 to explain his assertion on the British daytime chat show Richard and Judy that the question, 'What came before the big bang?' was meaningless, he compared it to asking, 'What lies north of the north pole?'" Chuck 19:26, 8 May 2006 (UTC)
Also keep in mind that cosmologists and astrophysicists are still not 100% certain abut the origins of the universe. This, for example, gives a different interpretation to the events around the Big Bang. Grutness...wha? 07:45, 8 May 2006 (UTC)

Celestial Names[edit]

When a new celestial object is discovered, it is immediately given a specific name (at least in English...its name in other languages may be different). I understand that our planets have been named after Roman gods, but this goes back to antiquity. I also understand that certain planets' moons are named according to a theme, for example (forgive me for forgetting which one) one planet's moons are named after Shakespearian characters. But that is also an old tradition. (Also, it seems pretty anglo-centric...are those moons named differently in different languages? For example in Russian are they named after characters created by Russian authors?).

What I'm really getting at though is, say a comet is discovered, or a new extra-solar planet. What organization or body is it that seems to have the authority to define these objects' names? Loomis51 02:04, 7 May 2006 (UTC)

The International Astronomical Union is the sole authority recognized worldwide on Astronomical naming conventions. (Though the IAU doesn't really name all the new objects discovered, generally the discoverer would be able to propose a name for IAU's approval.) --Lorenzarius 03:59, 7 May 2006 (UTC)
See also planetary nomenclature. -Yummifruitbat 04:00, 7 May 2006 (UTC)

Queer Printing on New Bills[edit]

This is for Americans. Does anybody know what anti-counterfeiting purpose it serves to make our money pink? Black Carrot 02:57, 7 May 2006 (UTC)

Pink? Is there a new bill that I haven't seen yet? I know that the bills have blue and red threads in the paper that is used. These threads are in the paper so that you can tell that someone didn't just print a scan of the bill on normal paper. There is more info about Counterfeiting and Security printing. Dismas|(talk) 03:59, 7 May 2006 (UTC)
See [19]. I think it's not so much that it's pink, but rather that there are multiple colors, and a gradient of color on the reverse. Ardric47 04:01, 7 May 2006 (UTC)
I lost my answer in an edit conflict, sorry. I did say however, that when giving money for ransom, the police often put a dye bomb in the cash-bags, that explodes and magenta dye covers nearly all the bills. --Usre:Mac_Davis (unlogged in) 11:35, 7 May 2006 (UTC)
Yes, when I went to the states a few months ago, I was quite suprised to see pink money! Kilo-Lima|(talk) 12:44, 7 May 2006 (UTC)
-sings- All things just keep getting better... Yes, there's a new bill. It's like...yellow and pink and green and still has dead people on it. Cernen Xanthine Katrena 13:52, 7 May 2006 (UTC)

well, why not pink? who says green is the definitive colour for money? surely you don't think that people might think your gay if you pay with pink money, do you? that would just be tragic!

(this comment was added by someone who doesn't know how to sign their own name)

Who says? I fucking say! I don't care about the sexual orientation of my money, I just don't want it to be salmon pink! Green and black. Nothing shiny, nothing pastel, just green and black. That's all I ask. And I still don't know, how in God's name is the color supposed to protect us? Complexity I understand, watermarks I understand, UV sensitivity I understand, but why PINK? Black Carrot 03:08, 8 May 2006 (UTC)
If you don't care about the sexual orientation of your money, why did you introduce that very concept in the title the question "Queer Printing"? Seems you're not as entirely indifferent to it as you claim. JackofOz 03:25, 8 May 2006 (UTC)
Yeah, and watch your god damn mouth. ^_^ Cernen Xanthine Katrena 09:59, 8 May 2006 (UTC)
In serious answer to your question the choice of colours is almost certainly intended to make colour reproduction as difficult as possible. Research has shown that colour copiers and printers have more difficulty with the pinkish purplish colours than any others. Which is why you will see that many countries are introducing high-denomination bills looking very similar in colour. DJ Clayworth 18:26, 10 May 2006 (UTC)

Red-eye effect in photography[edit]

Does anybody know the technical term for the "red-eye" effect in photography? I thought that it began with "hemo-", but I might be totally wrong. Please, please, please, if anybody knows, I'd greatly appreciate it. (I doubt that I'll be able to sleep until I find out!)

Sorry, I don't know and there is no mention in the article: Red-eye effect. Andrewjuren(talk) 06:45, 7 May 2006 (UTC)
"Hemo-" means blood, so we are on the right track. However, the OED has no technical term for this effect. Interestingly, Googling for hemo and "red eye effect" suggests the word was in the Wikipedia article in an earlier edit, but I haven't been able to find it. Hope you got some sleep! --Shantavira 07:58, 7 May 2006 (UTC)

Intelligent Design[edit]

Many evolutionary scientists have criticized and refuted the arguments given for Intelligent Design.Well, how have Michael Behe,William Bemski, and other advocates of Intelligent Design reponded to these criticisms?

Have you tried looking at our article on Intelligent design and related articles listed under "See also"? Andrewjuren(talk) 06:48, 7 May 2006 (UTC)

Indian Almond[edit]

How the Indian Almond look like? Is it called 'chinabadam' in Bengali language?

Unfortunately, our article on Indian almond does not have a picture. There is a good description on this external site. Andrewjuren(talk) 07:23, 7 May 2006 (UTC)
I've found a free image; it'll be up in a minute. Melchoir 08:06, 7 May 2006 (UTC)
Image:Teca 001.jpg. For future image hunters, this is the second result if you Google for ("indian almond" usda). Melchoir 08:17, 7 May 2006 (UTC)

refractive index of sugar[edit]

does sugar have a refractive index?

It sure does! According to Sucrose, the refractive index of a sugar crystal is 1.5376. Melchoir 08:19, 7 May 2006 (UTC)
Also, if you look at refractometer you should probably find some stuff on the refractive index of different concentrations of sucrose solution, as that is the standard against which other concentrations are determined with these machines. Skittle 16:14, 7 May 2006 (UTC)
Sugar dissolved in water will also change the refractive index of the solution. And it will vary with concentration, so you can use that as a way to determine the sugar concentration with a refractometer (typically an Abbe refractometer to be precise). It's a good-old fashioned kind of chemical analysis instrument you don't see that often nowadays. --BluePlatypus 18:15, 7 May 2006 (UTC)
(Addendum: Apparently I'm not only old, but a bit blind too, since I somehow missed that Skittle had given essentially the same answer). --BluePlatypus 18:19, 7 May 2006 (UTC)
Hey, it's probably the chemical analysis intrument I see the most of. And Blue Platypus's answer was better. Brix scale if it helps Melchoir. Skittle 13:46, 8 May 2006 (UTC) (Hmm, seems to be red. Brix has some info, but not as practical as it could be)

Light[edit]

Is there an existing material that can travel faster than light?Does wikipedia have an article on it?i would love to check it out

--thanks

I think the closest we've got is Tachyon. Since tachyons have not been observed, I wouldn't call them existing materials, though. Melchoir 08:22, 7 May 2006 (UTC)
Keep in mind that going faster than light is equivalent to going back in time. See Introduction to special relativity for the details. —Keenan Pepper 08:34, 7 May 2006 (UTC)
It's probably not true that being a tachyon means traveling back in time (or FTL travel). Rather, it just means an odd dispersion relation until the stable vacuum is reached. -lethe talk + 09:45, 7 May 2006 (UTC)
Isn't there some law of physics relating to e=mc2 that says it is impossible to overtake light if you are slower than it, and go slower than it if you are faster than it. And also that objects that are faster than light cannot interact with objects slower than light? I' not actually sure, and I don't know where to look to verify this, so if anyone else who knows about this could so, it would probably help. But more to the point, if I am correct, there may be things going faster than light, but it is impossible for us to know. Philc T+C 09:30, 7 May 2006 (UTC)
I don't know about the interaction bit, but your first point is indeed echoed at Tachyon. Melchoir 09:36, 7 May 2006 (UTC)
Ah, yes, I found it at tachyon, if a Tachyon does exist, and travels faster than light, if we were able to interact with it it would violate causality, as loops in time could be created leading to plentiful paradoxes, therefore if they do exist, there is no way for us to know. Philc T+C 18:04, 7 May 2006 (UTC)
Cherenkov radiation might also be an interesting read if your question was not limited to the speed of light in a vacuum. It's also been mentioned above. - Dammit 10:22, 7 May 2006 (UTC)
A great answer is Is Faster Than Light Travel or Communication Possible? in Usenet Physics FAQ. We also have an article FTL. – b_jonas 12:50, 7 May 2006 (UTC)
Anyway, the short answer is that it isn't possible because physicists have once decided that it wasn't, and since that time they keep redefining FTL so that it would exclude any possible way of travelling faster than light so as to guard their self-pride. – b_jonas 12:55, 7 May 2006 (UTC)
Well, to be fair, the examples given in that article do seem pretty useless. Unless you can pilot a spaceship or send messages across the galaxy, what good is it? Black Carrot 02:59, 8 May 2006 (UTC)
Actually, recently Brian Greene gave a talk and he is the leading physicist in the field of quantum mechanics and string theory. He said, and I know cuz I was there, that if you have two quarks, and look at one and it's and UP quark, then according the the laws of physics the other must be a down quark. He said that this took place instantaniously, faster than light. I asked him 'What if you could affect the outcome of the quark? Wouldn't that cause for Faster-than light communication?' and he said 'Yes, if you could.'
That would be a case of quantum entanglement. The main problem is that affecting the outcome, based on curent models of quantum dynamics, is impossible. On the other hand, it does provide a neat means of creating a unique key for cryptographical purposes. Confusing Manifestation 13:26, 14 May 2006 (UTC)

This means that perhaps in the future the topic could lead to faster than light communications/information transport for teleportation. Turtleboyxtreme i do not know when.

detecting UV rays[edit]

i know that human eyes cannot detect UV rays.but is it possible to have any sorta eye surgery so that our eyes can spot UV rays without any damages?

No, we are not yet advanced enough that we can modify the cells on our retina in such a profound manner. — QuantumEleven 09:13, 7 May 2006 (UTC)
We can get Infra-red goggles, so If you are determined to see UV, im sure its possible to make some goggles that pick them up or something. Philc T+C 09:32, 7 May 2006 (UTC)
We would also have to alter our brain, to be able to register the new colors. -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. Mac Davis 10:26, 7 May 2006 (UTC)
Infra-red is actually the opposite of UV, so i doubt that typical Night vision goggles would be much help. The trick to seeing UV rays is actually not hard, since they are energetic. Simply get a filter that only allows for UV rays to pass through, and then hit a material that will fluoresce properly, to convert the UV rays to normal light, and just watch them! This is how you 'see' things in a room lit up by only an ultraviolet bulb, visible light is supressed and only objects that fluoresce the light back to the visible range show up, like white socks, teeth, psychadelic posters, etc.
It is entirely possible, except it probably counts as damage: see Aphakia. Ardric47 20:05, 7 May 2006 (UTC)
There exists a device known as a starlight scope. I believe it uses ultraviolet from the stars at night to see.

Remember that UV radiation carries a lot of energy per photon; in fact, enough to be damaging to living tissues. Life as we know it today, above the ocean or soil surface, would not be possible without the ozone layer in the stratosphere that absorbs much of the UV coming from the Sun. By and large, there is relatively limited exposure to UV at sea level (just enough to tan...), but exposure does increase either with altitude or in regions located in the so-called ozone layer. --Michel M Verstraete 21:17, 12 May 2006 (UTC)

Some human children can see into the UV spectrum but eventually lose the acuity. Children can generally hear higher pitches than adults as well- call it ultrasound based on being above the arbitrary mark of pitches most adult humans can hear. --151.151.21.100 20:54, 2 August 2006 (UTC)BEN 8/2/06

Scientists investigating crashed spaceship[edit]

I'm writing a story that involves a crashed spaceship, among other things, and originally I just had SAS soldiers securing the site (plot device to get my characters there). It occurs to me that the government would also send scientists to investigate it. After all, that's what they do in movies and so on.

But exactly what kind of scientists would be sent? I can't imagine we have too many people lying around with a degree in extraterrestrial technology study.

Physicists, biologists and chemists I guess. - Dammit 10:24, 7 May 2006 (UTC)
NTSB with NASA-people, me'd think. 213.161.189.107 10:29, 7 May 2006 (UTC) Henning
Astrophyscists, engineers, nanotechnologists, & geologists (for examining the spaceship) biologists, bio- and astro- chemists, read Deception Point for more. For specific people, maybe you could add Michio Kaku and... that's all I got. Assuming its in the future. Don't forget Delta force, in case anything funny happens with the aliens. -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 10:33, 7 May 2006 (UTC)
Well, if SAS soldiers are being sent in, I'd presume that the crash doesnt take place in the United States, so I can't see a US-government task force being the first on the scene. GeeJo (t)(c) • 11:47, 7 May 2006 (UTC)
Thanks. It does in fact take place in Australia, in the Snowy Mountains to be specific. I'm especially pleased you mentioned a nanotechnologist; nanotechnology plays a part later on in the story, and putting one in beforehand means I can set up an udnerstanding of it before the reader actually has to cope with it as part of the plot.
Stargate's universe has all sorts of people brought in to study strange things: Daniel Jackson is an archaeologist and linguist...Rodney McKay is an astrophysicist...and, yeah, take along a few guys with P90's just in case things get out of hand. Cernen Xanthine Katrena 13:34, 7 May 2006 (UTC)
Alot of stories send mathemiticians on trips to communicate with other life-forms, as it is the only common language we will have. Philc T+C 15:24, 7 May 2006 (UTC)
What makes you think our math would be even vaguely similar? And how do you use that as a language? Black Carrot 21:19, 7 May 2006 (UTC)
Maths is always the same, no matter where you go in the universe 2+2=4 F=ma and e=mc² so thats how its vaguely similar. addmitadly it cannot be used to communicate much, but it allows both species to gauge the others intelligence. However little you can get across, its better than just sitting there squeeling at each other in your respective languages at your respective frequencies. Philc TECI 21:45, 7 May 2006 (UTC)
Alright, let's assume we structure our quantitative views of the world more or less the same. Let's just say. How, then, are we supposed to communicate our understanding to the aliens without language? Cut up some squares and demonstrate the Pythagorean theorem? Black Carrot 02:42, 8 May 2006 (UTC)
The prime numbers are generally the best idea for a start. Then do the periodic table to demonstrate scientific understanding. --212.241.231.52 03:19, 8 May 2006 (UTC)
Even if you can only cut up squares and show each other pictures, all you have to do is show them a number square, and it would take seconds to grasp the ten based decimal system. There are only four basic functions, plus minus multiply and divide, so once weve got them acroos, you can discuss mathematics. However pointless it is there is no other way of communicating anything! ok! its better than nothing!!! Philc TECI 11:12, 8 May 2006 (UTC)
I hope the aliens aren't made of antimatter. That would be bad, eh?
They'd send expendable scientists. AllanHainey 15:33, 8 May 2006 (UTC)
It sounds like the scientists are secondary characters; in which case, in traditional science fiction, all of them are expendable. Black Carrot 23:10, 8 May 2006 (UTC)

Visible Spectra of Light[edit]

IN THE NAME OF HOOLA, there's edit conflict for a reason! Don't just delete my article like that! *hrm*... now. Humans see roughly from 400nm to 700nm waves (IIRC). First of all I would like to ask: If we could see from, say 300nm to 800nm, would we perceive the colours as the same, but "spread out", ie seen only a stretch? Then there is another, bit tougher question: Some animals are bound to have different spectra, what are the lowest and highest wavelengths that some animals can perceive in vision, that we know of? Manymanymanymany thankseses. :)

Sorry, it was me. Accident. The colors would not be the same at all! We would see completely new colors. Colors that we literally can't imagine. The lowest and highest are of the animal kingdom seen ultraviolet and infrared, although I am not sure of the wavelengths. --User:Mac_Davis (unlogged in) 11:31, 7 May 2006 (UTC)
Oh, thanks. Definitely not my intention to come off as cross, I should have placed a smilie in. ;) Thanks - it's the wavelengths that I'm interested in.

Who's Hoola and why don't we have an article on his/her worship? alteripse 16:28, 7 May 2006 (UTC)

Are you guys British or something? What does cross and hoola mean? -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 04:48, 8 May 2006 (UTC)
Cross: angry, annoyed [20]. Black Carrot 23:15, 8 May 2006 (UTC)

Traffic Lights[edit]

Okay, this'll probably get me banned from the reference desk. Let's pretend there's this traffic light at an intersection that never works properly, and despite the amount of protests and complaints to the state transportation (and whomever deals with transportation in the county, as well), nobody has come out to fix it. Let's also pretend that I'm fed up with said traffic light and wish to perform malicious action on said traffic light to force the DOT to come fix the damn thing. My question is, what would send a clear message and not allow me to be caught (hypothetically): a localized electromagnetic pulse (and how would one construct a device to do that)? A small explosive? It would, of course, be mounted on the control box. Cernen Xanthine Katrena 13:25, 7 May 2006 (UTC)

No hope, those things can take hurricanes. With our local paper, they have a daily article on the 'fixer', in which people complain about potholes and such. They are usually fixed the next day. --Zeizmic 13:38, 7 May 2006 (UTC)
Low-yield EMP bomb? :D
You could get one of those devices that ambulances and fire trucks use to change the lights for them while they are approaching it. Although, it's illegal for private citizens to own one... but you know... Dismas|(talk) 15:41, 7 May 2006 (UTC)
While traffic lights might not be susceptible to hurricanes, they do not survive lorry fires adjacent/right beneath them (there was one such incident in Wells a few years back). Alternately thermite might do the trick... Thryduulf 15:48, 7 May 2006 (UTC)
Well, it depends. If it doesn't have cameras attached (a lot of the ones around my house do, to catch people speeding), it gets alot easier. Wait for a time of day (or night) when there's nobody around, climb up on it, and smash one of the lights with a hammer. Or, cover it with paper; it'll still be disabled. As far as getting banned, people have asked about the mechanics of suicide in a padded room. Questions aren't a problem, as long as they're actual questions and not reformatted speeches. Black Carrot 21:10, 7 May 2006 (UTC)
If you are trying to create an emp grenade you have several options a capacitor bank (one about the size of a small house would do the trick), a specially construced tool which uses a spinning disk going very fast to cut through the field lines of magnets, so when the circuit is completed for a split second you will have mabye a Megamp of current (sorry can't find its name anywhere), or you can use a current going through a coil (an electromagnet) and use small explosives to collapse the coil very quickly, this will cause an incredible rise in current, and since its already a coil, voila emp. But all of this is pretty unpheasable for the task of dealing with trafficlights, mabye you should just tie them to your car and yank them over, or even easier, as someone suggested earlier i think, set off a large nuclear weapon in the upper atmosphere. ;-) Philc TECI 22:00, 7 May 2006 (UTC)


Perhaps you could do it the old-fashioned way? --Crucible Guardian 23:29, 7 May 2006 (UTC)

I considered suggesting that (in fact, I did suggest something like that), but there's the problem of reach. Black Carrot 23:38, 7 May 2006 (UTC)

Well. I don't think I could detonate a nuclear warhead (my insurance doesn't cover fallout from even accidental detonation of a nuclear device -- what a load of crap, hm?). And so much for the emp grenade. I could hit it with a sledgehammer, but there's a 7-11 right in front of it (which means that I can be caught...). It's not the lights I want to damage, it's the control box. They'll have to send a technician instead of just a repair crew, it'll be costly, and painful, for the county to do that. I was thinking of hitting it with the sh*tmobile...do you think a vehicle accident would take one of those puppies out? After reviewing a wikibook on thermite synthesis, I think I may have my answer, but the question is, is such a reaction simply incendiary or explosive? Cernen Xanthine Katrena 10:15, 8 May 2006 (UTC)

http://video.google.com/videosearch?q=thermite - mako 11:48, 8 May 2006 (UTC)

Yeah! Vandalism is the answer to real life problems as well as Wikipedia problems! --Ginkgo100 15:59, 8 May 2006 (UTC)

Yeah, it bloody pisses me off to when your neighbours accidentally set off their nuclear warhead, and then you have to ask them to cover the damages, because your insurance doesn't cover it! Philc TECI 22:32, 8 May 2006 (UTC)

I'd get three large stickers, one with "green" written on it in text (it doesn't matter what color), one with "orange" (or "yellow" if you wanna be nasty) and one with "red". Climb up the pole and stick them on each of the lamps, but not so much as to obscure the actual light, so that all the people that weren't colorblind wouldn't get confused.
You wouldn't cause enough damage to get into trouble, but your government would be enclined to set things straight, and there'd be a good chance they'd fix the other problems while they were at it.
Also, it helps if you live in one of those towns that has horizontal streetlights, like Montreal, which would make it even harder for the dumb colorblind people to tell which was which.  freshgavinΓΛĿЌ  07:07, 10 May 2006 (UTC)

carbon in body[edit]

carbon isnt necessary for human survival,yes.But is it that carbon is needed atleast in little content in our bodies?or maybe i am wrong?If not,what are the diseases caused by deficiency of carbon?

--thanks!

I imagine starvation. Just about everything we consume has carbon in it. I don't know how the uptake of carbon works, if there is any.
  • Perhaps the questioner is referring to pure carbon as opposed to carbon compounds? --jpgordon∇∆∇∆ 15:04, 7 May 2006 (UTC)


--yes,as a matter-of-fact i was reffering to pure carbon and not carbon compounds.thanks!--the same person who asked the question:)

As in charcoal, graphite, diamonds or bucky balls? I don't think so :) -Obli (Talk)? 16:25, 7 May 2006 (UTC)

No, your body cannot do anything with pure carbon, however in cases of drug overdoses, paramedics often deposit activated carbon inside a patient's stomach to absorb the toxins --Crucible Guardian 23:25, 7 May 2006 (UTC)

I don't know if they still recommend it now, but 30 years ago, my dad was given charcoal tablets to try to deal with his upset stomach; same principle, I assume. --jpgordon∇∆∇∆ 23:43, 7 May 2006 (UTC)
There is also the idea to use fullenes to deleiver medicine [21]. --Chapuisat 20:08, 8 May 2006 (UTC)
Here's a link to the article on activated carbon, so that the person who wrote the original question can read about its huge surface area. Arbitrary username 15:45, 8 May 2006 (UTC)

Another computer problem[edit]

I have recently received a computer [for free] from my father’s company. He didn’t want it, so now it’s mine :P. I have a weird problem though: every time I turn it on, the computer asks me to log in with a username and password. FWIW, the computer runs on Windows 2000 Professional. I’ve tried to get around the login by going into safemode and whatnot, but it always ends up on the login screen. Even if I type in a legitimate username and password, I can’t get through, because the computer is making a vain attempt to connect to a server that no longer exists. My question is this: is there a way for me to disable the network login without being able to bypass the login or having boot disc for Windows 2000? Perhaps there is a way to get into DOS upon startup and disable networking…?--The ikiroid (talk)(Help Me Improve) 16:44, 7 May 2006 (UTC)

Wipe the hard disk and install Linux. --Trovatore 20:53, 7 May 2006 (UTC)
If you don't like Trovatore's suggestion (I may be a penguin fan, but it's not always the right solution) there should be seperate "Safe mode" and "Safe mode with networking" options. Also, at the login screen you should be able to select between logging in locally and using a network (domain) login - if you don't get a third box to select that beneth the username ansd password boxes then click "Options" and it should show up. Another possibility is that the recovery console may be installed - if it is then it will be shown as an option on the boot menu, you will need the local admin password to use it. -- AJR | Talk 23:04, 7 May 2006 (UTC)

With old corporate, networked PC's and laptops, the only answer is to go to Linux. First, for a corporation to give it away, it has to be really old! Second, the corporate IT-jocks have probably really done a number on it, for 'security'. I've had lots of success with those throw-aways and Linux. --Zeizmic 23:45, 7 May 2006 (UTC)

You'll get nowhere without admin priviledges, that is the way the system is designed, and it is quite good at it. If you cannot get these passwords (company may not want to reveal these), you can ask your dad to get the company IT person to add an admin account for you (he would have to take it in for this). Then all the logins and startups can be accessed and changed, using the new admin account. The simplest is really installing a system that you own - sounds like you are most comfortable with Windows, but that costs, whereas Linux is free, and the newer GUIs are relatively easy. If the system is running Windows 2000 it can't be too old. --Seejyb 11:20, 8 May 2006 (UTC)
Umm, well here's the other big twist: the company doesn't exist anymore. I guess I forgot to mention it's my dad's old company.--The ikiroid (talk)(Help Me Improve) 11:48, 8 May 2006 (UTC)

Then you are attacked by the proverbial helical inclined plane. --192.75.48.150 12:13, 8 May 2006 (UTC)

Try this[22] site to get access to admin account. With access to the disk the data can always be read, updated and changed, a computer is not that hard to break. Stefan 07:09, 9 May 2006 (UTC)
Will that work with Windows 2000? I don't need the data inside. BTW, I'm willing to format the hard drive to erase everything except Windows 2000.--The ikiroid (talk)(Help Me Improve) 01:28, 10 May 2006 (UTC)
Did you read the web page? Tested on: NT 3.51, NT 4 (all versions and SP), Windows 2000 (all versions), Windows XP (all versions, also SP2), Windows Server 2003 (at least Enterprise)., how can you format everything except windows 2000? and if you could, if you can not login it still does not help. If you are prepared to reinstall windows then just do that! Stefan 06:13, 10 May 2006 (UTC)

Diamonds: How many are consumed by the United States AND How many diamonds are extracted in the United States?[edit]

Diamonds: How many are consumed by the United States AND How many diamonds are extracted in the United States?

Thank you so much.

Are diamonds actually consumed? User:Zoe|(talk) 21:04, 7 May 2006 (UTC)
I dont know, its strange, consumers do something with them, the name suggest consumers consume, but to me atleast it implies ingestion... Philc TECI 22:02, 7 May 2006 (UTC)
I had 20 diamonds for breakfast today. Perhaps you want to consult our article on diamonds?--Frenchman113 on wheels! 20:51, 9 May 2006 (UTC)

History of Health Screening[edit]

My stepdaughter has been trying to find information on the history of Health Screening (as we are in the UK, I suppose with a UK bias) and has had little success. I too have tried and not really found anything. Could someone please point us in the right direction or give us some information. Many thanks. emjay----------

Fullerene[edit]

I had heard about fullerene, and learned a few thing about it, but never seen it until I saw the wiki article on it, where it shows the compound in crystalline form. I thought, how is fullerene bonded as a solid, was this at extremely low temperature, or is there a bond between the balls, or what, are they held together by Van der Waals, if that is possible. If they are, how can they stay together at high temperatures. Also the same question about buckminster fullerene, as that has Carcons with only 3 bonds, which would make inter molecular bonds possible (wouldn't it) so is that bonded differently? Philc T+C 18:46, 7 May 2006 (UTC)

Indeed, they are held together by VdW forces, and are therefore weak and soft as a solid. They sublimate at high temperatures. The carbons have more than three bonds, though - it's a conjugated system, so while it's possible for them to bond to other molecules, but that would break the aromaticity of the system, so they're not very happy to do so. --BluePlatypus 20:18, 7 May 2006 (UTC)

the gay gene[edit]

hi, now that its estabished that people are gay through nature rather than nuture, does anyone know whether there was definitive study that drew this conclusion or was it more a set of smaller ones that tended towards it? if anyone could direct me to them then that would be great. also, i would appreciate it if bigots wouldnt post their vitriol here... thanks! andrew

Biology and sexual orientation. -lethe talk + 19:40, 7 May 2006 (UTC)


There is almost certainly no single "gay gene". If homosexuality were a simple Mendelian trait, this would have been known for a long time. People with axes to grind on both sides like to describe homosexuality as though it were one single well-defined thing, but human beings are a bit more complicated than that. --Trovatore 19:42, 7 May 2006 (UTC)
"now that its estabished that people are gay through nature rather than nuture" - So, every single experiment peformed everywhere in the world by every scientist has proven that people are gay through nature, not nuture? Wow. That's news. I'm surprised to find it in the Wikipedia Reference Desk and not on CNN. Or... is this just another troll using a false assumption to pose a baited question? --Kainaw (talk) 22:39, 7 May 2006 (UTC)
WP:AGF. Arbitrary username 16:15, 8 May 2006 (UTC)

Homosexuality is most definatly not caused ONLY by genetics. Several studies on identical twins have been done that show that genetics probably plays a roll, but if genetics were 100% responsible for homosexuality, the percentage of twins that had the same sexual orientation would be 100, but it is not even close. It's more like 40-something. --Crucible Guardian 23:20, 7 May 2006 (UTC)

While I agree with you that it's certainly not 100%, 40% seems a little low. I haven't seen any recent statistics about sexual orientation (maybe someone could find some), but the most recent ones I remember seeing is that something like 10% of the population identify themselves as homosexual. (Note: I realize sexual orientation is much more complicated than a two-bin or even three-bin system, but I'm simplifying it for statistics sake.) Even if you up that to 20% of the population being homosexual or bisexual and 80% of the population being heterosexual, that would mean that if you pick two people at random, 64% of the time you would have two heterosexuals. So wouldn't 40% imply that twins are more different in their sexual orientation than two random people off the street? EWS23 | (Leave me a message!) 23:49, 7 May 2006 (UTC)
Not sure, but I think Andrew might have been thinking of this article - which, for the record, is still a long way from "establishing" that homosexuality arises from nature as opposed to nurture. -- Filliam H Muffman 03:48, 10 May 2006 (UTC)
It's worth noting that the binary distinction (hetrosexual vs homosexual) or even trinary (hetro, bi, and homo) is not granular enough. Alred Kinsey put people on a 0 to 6 spectrum (the so-called Kinsey scale), and found that found that 46% of people were bisexual, to varying degrees (see Kinsey_Reports#Sexual_orientation). Raul654 03:55, 10 May 2006 (UTC)

petroleum distillates[edit]

Are petroleum distillates absorbed through the skin? I'm having trouble finding out information. If they are absorbed, what is the effect on the body? KeeganB

The problem is that "petroleum distillates" is a huge group of products. Some are absorbed and some aren't. For example, some petroleum disillates are skin lotions - if they weren't absobed, they'd be useless. Other petroleum disillates are like a wax (such as the waxy coating on milk cartons). It isn't absorbed by the skin because it is too hard of a wax - if it wasn't it too would be useless. Of the literally thousands of products made by petroleum distillation, you need to specify which ones you are concerned about. Obviously, the effect of absorbtion would be different depending on the product. Skin lotion makes your skin softer. There are some aromatics that make your skin smell better (or at least different than the normal skin smell). --Kainaw (talk) 22:49, 7 May 2006 (UTC)

I'm talking about the kind in furniture polish. KeeganB

Oh, nevermind, I managed to find the MSDS. The answers is no. I'm such a fuck up. KeeganB

Hmmm... someone is calling themself a rude name and not me. I think I answered the question wrong. --Kainaw (talk) 00:04, 9 May 2006 (UTC)

May 8[edit]

Boy with 'no brain'[edit]

This post claims that someone with only 1 cubic mm of brain tissue functioned normally, and a search for the professor mentioned in the post reveals similar stories. Do you know if this has ever been published anywhere reputable, or is it just a spontaneously generated bit of wishful thinking?

The article you mention was certainly published in Science Magazine (1980, 210, 1232-1234) which is a reputable journal, your interpretation of the facts in the post that you link to are not accurate. Here is a better description of the article which discusses the thickness of the cerebral cortex (a PORTION of the brain) and not the volume of the brain as a whole. Still, the article raises many questions. -- C. S. Joiner (talk) 00:42, 8 May 2006 (UTC)
I looked up the article (citation above). While Science is a highly reputable journal, it's in the "Research News" section, which means it's not a research paper, nor is it subject to peer review. Anyway, Lorber is quoted as saying "we saw that instead of the normal 4.5-centimeter thickness of brain tissue between the ventricles and the cortical surface, there was just a thin layer of mantle measuring just a millimiter or so.". Later in the article, a neurosurgeon points out out the difficulty of interpreting brain scans ("Interpreting brain scans can be very tricky. There can be a great deal more brain tissue in the cranium than is immediately apparent"), and is quoted as saying "Lorber may be being rather overdramatic when he says that someone has 'virtually no brain'." And Lorber acknowledges as much, but still says that the brain must nevertheless be substantially smaller than normal. So as pointed out, it's only a particular portion of the brain that's being referred to there (and then as "a few millimiters" as opposed to 4.5 cm). And that should probably be taken with a grain of salt. The overall impression of Lorber seems to be that he's fairly well-respected but considered something of the kind of provocateur who likes to make big claims and challenge preconceptions. (other controversial ideas of his are mentioned) In other words, worth listenting to, but not trusting blindly. In any case the "One cubic millimeter" claim is certainly false. But the gist of the thing - that there's someone out there with high IQ and a substantially smaller brain than most, is probably true. The main point of debate seems to be (or have been at that time) what role the cerebral ventricles play. --BluePlatypus 01:08, 8 May 2006 (UTC)
And the cubic millimeter aspect refers to the thickness of a layer of cortex tissue, as I understand it, not a total volume of brain tissue. It is not a little cube of brain; it is a very squashed down and/or thin brain tissue. --Fastfission 01:59, 8 May 2006 (UTC)
There is no "cubic millimeter", that was a misreading. Black Carrot 02:35, 8 May 2006 (UTC)

Turkish Quadrupeds[edit]

Whatever happened to this story? Seems to have fizzled out. JianLi 00:56, 8 May 2006 (UTC)

What were you expecting? --BluePlatypus 01:39, 8 May 2006 (UTC)
Good question. I'm not sure exactly. The announcement that the whole thing has been a great fraud? Or, if not (since reputable news sources are carrying it), a conclusion regarding the cause of it?JianLi 02:52, 8 May 2006 (UTC)

it's really cool anyway

I remember watching that programme in the UK; it's a real shame for them. Kilo-Lima|(talk) 20:13, 8 May 2006 (UTC)
side note: i just read a story on them in Discover magazine. it was basically about how the media circus made a big deal out of nothing. -Jian

Pulse Jet[edit]

If a valveless pulsejet were to be built with a cruved pipe, with out a camber and increasing or decreasing pipes, would it still work? Patrick Kreidt

Medical Formulations[edit]

Why do most medications have HCl in their formulations?

Because they get absorbed faster your digestive system if they're a hydrochloride. --BluePlatypus 01:39, 8 May 2006 (UTC)
That's a rather bold statement. Surely you have some evidence to back that up? --Chris 03:20, 8 May 2006 (UTC)
What's bold about it? Note that I'm not saying everything gets absorbed faster as a hydrochloride. Nor did I say that it's the only reason hydrochlorides are used. If you expect a short, simple Reference Desk answer to a short, simple question to be an all-encompassing absolute truth of biochemistry, you're nuts. But no, I don't have any evidence of that. It's just what I was told in the (albeit introductory) class I took in pharmaceutical chemistry. Making something a hydrochloride salt can make it more water-soluble and faster to absorb in the digestive system. It seemed like a reasonable explanation to me then, and I assume that the people at the drug companies have the evidence to support it. I'm not exactly in the position to give a full review of all available litterature on pharmaceutical salts (and there seems to be a good amount of it), although I do feel pretty confident it doesn't contradict what I wrote. So what exactly do you think is wrong with that statement? --BluePlatypus 04:46, 8 May 2006 (UTC)
...Hydrochloride -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 04:46, 8 May 2006 (UTC)
Yeah, I just found that myself and was about to point it out. Hopefully it was written by someone with more direct experience than myself. At least it appears so from the details. --BluePlatypus 05:03, 8 May 2006 (UTC)
In general, most organic compounds such as pharmaceutical drugs are more soluble in water when they are in a charged (ionic) state rather than a neutral one. A large number of drugs contain nitrogen atoms than can be readily converted to ionic ammonium salts by the addition of an acid. The ammonium salts tend to have better bioavailability than the neutral compound because of their better solubility. There are many pharmaceutically acceptable acids that can be used to form the salts, but hydrochloric acid is common because it is a strong acid that will completely form the ammonium salt. And there is plenty hydrochloric acid in your digestive system already, so it is unlikely to cause problems. --Ed (Edgar181) 11:57, 8 May 2006 (UTC)

plant question[edit]

does co2 in a plant travel through xylem, phloem, or...?

You may be thinking of stoma; CO2 that enters there doesn't have to travel very far to get to the places where it's needed for photosynthesis. --AySz88^-^ 03:37, 8 May 2006 (UTC)

ok. the longer explanation follows. im taking the bio ap tomorrow, and my teacher gave us a take-home open-note (and internet, but not fellow student) test on the last section we'd need to know for the ap. one of the questions was: "If radioactive CO2 is supplied to a mature leaf of a plant, it is often possible to detect radioactivity in the young growing leaves of the shoot apex a few hours later. In which tissue did the radioactive compound(s) travel? a. phloem b. xylem c. stomata d. cortex e. pith"

I'm @$&# near positive it's not cortex or pith because that wouldn't make any sense and pith doesnt even really fit in the whole picture. i know the stomata accept the CO2 and transpire away water, so i was thinking the xylem would carry it, because it doesn't seem to me that the stomata, being small, single cells, could be the "tissue" (if they're considered tissue, which I think they're not)in which the compounds "travel." sorry i didn't elaborate earlier, and thanks for the help

The teacher is probably testing for some insight here: In the leaf, CO2 is incorporated into sugars via photosynthesis (hence the word supplied); how are sugars transported? --Seejyb 11:36, 8 May 2006 (UTC)
The C02 moves int through the stomata where it immediately enters a palisade cell, energey is used from a light source to combine the CO2 with H2O to make C6H12O6 (glycerol) this is then transported around the plant via the Phloem cells, the xylem cells are solely for carrying this up from the root, the phloem move in any direction. so CO2 travels through stomata only, the C (which would be the radioactive part of CO2 most likely) would then travels about the plant in sugars, which are in the Sap. Philc TECI 14:16, 8 May 2006 (UTC)
basically correct, but I'd like to point out that C6H12O6 is glucose, not glycerol. GeeJo (t)(c) • 18:40, 8 May 2006 (UTC)
oops hehe, cheers for pointing that out ;) Philc TECI 22:30, 8 May 2006 (UTC)

thanks

very general physics[edit]

i am a highschool junior who has enjoyed science for years but has no particular affinity or interest in pursuing it heavily in college or as a job. so i signed up for the harder of two AP physics courses at my high school, which i'm supposed to take after learning calculus, when i haven't yet learned calculus (i'll be doing it concurrently), because the other course doesn't sound as interesting. i'm excited, but the course is supposed to be really tough, and i want to prepare as much as possible for it over the summer. any books anybody'd suggest i read to help me with understanding the physics (or calculus) basics? if i was just to try to learn physics basics on wikipedia, how should i go about doing that? they have a "where to start" section, but it didn't help much because i have no idea what i'm looking for. thanks so much to anyone who can help

Well.. I'd suggest working from a textbook. Wikipedia is (or tries to be) an encyclopedia, and as such isn't really that great for learning physics and math. (in my opinion) It's better to work from a textbook where the things build on eachother naturally, and where you can solve problems and make sure you understand things properly before moving on. Both are the kinds of subjects where if you skip ahead, you can miss some of the basics and have to pay for it later through lots of confusion. (I've been there plenty of times myself) On the other hand, if you've got a solid understanding of the basics, you can get pretty far on that alone. So I'd suggest seeing if you can get hold of the textbooks you're going to use, and start studying the first couple of chapters or so and build up a solid base. Or you could at least build up your existing skills and make sure that you're completely at home with the level of math and physics you're supposed to know so far. It's always easier to build on a solid base. --BluePlatypus 04:16, 8 May 2006 (UTC)
(Stop edit conflicting me! :p)
Coincidentally enough, I'm going to be taking this test tomorrow (and while I wrote this, my "tomorrow" became "today" >.< ).
Basically, I would comb over the Physics C Course Outline and concentrate on learning concepts. Personally, I needed a little extra effort to grasp concepts in rotation, like torque or angular momentum, and in electricity, like Gauss's law and voltage. (If, while you learn things, you encounter anything that you don't understand and/or is too mathy in Wikipedia, I would come back and ask here for help.) You'll probably also want to be familiar with concepts in calculus, like the meaning of taking a derivative (finding instantaneous rate of change) or an integral (adding up lots of small changes), and what the symbols mean (all the equations you need to know from calc are on the reference table). You might want to know just the concept of a surface integral - but you don't need to know how to do it - so you're not too confused when you see that symbol.
Our school actually takes Physics B and Physics C in sequence - two years in total - so you'll have to cover a lot of ground! (But B has some extra junk that C doesn't have, so that shortens things a bit.) Good luck! :) --AySz88^-^ 04:18, 8 May 2006 (UTC)

im taking the bio ap tomorrow. good luck too and thanks to both of you

(edit conflict again >.<) Oh, speaking of textbooks, there's a list from the folks at the College Board. Mine is the second one, "Physics for Scientists and Engineers". Don't just look at the first couple of chapters; that would be lethal with something with so many topics. I would look at the first few sections of each chapter, skipping the calculus-heavy parts.
Thanks, and good luck again! :) --AySz88^-^ 04:25, 8 May 2006 (UTC)

endocrine system[edit]

The chief cells of the the parathyroid glands produces a hormone that does what?

Homework? --BluePlatypus 04:02, 8 May 2006 (UTC)

parathyroid hormone (it's a wikipedia entry) - increases blood calcium levels, wheareas calcitonin (in the thyroid) decreases it

Faster Than Light[edit]

I've heard that light is the fastest thing in the world and nothing travels faster than it.But instead of saying that light is the fastest thing in the world, why don't we say that light is the thing that's known to be the fastest thing in the universe?I mean, what if there are things that travel faster than light, but it's just that they haven't been discovered?User:Bowei

  • Instead of "it is known to be the fastests thing in the universe" which implies we are absolutely certain there's nothing faster, I would say "light is the fastest known thing in the universe". By the way: Anything that travels faster would go against a few basic physical theories whose formulas include the constant c for the speed of light. We know it's the fastest because the mathematics say so. - 131.211.210.11 07:55, 8 May 2006 (UTC)
The Theory of Relativity, which has been extremely succesful thus far, says that some very weird things would happen if anything went faster than light. It makes accelerating through the speed of light impossible, since the energy required to even reach the speed of light would be infinite. Hypothetical particles that are always faster than light are called tachyons, and they present problems for causality, as you can read in the article. -- SCZenz 08:50, 8 May 2006 (UTC)
Interaction between things that are faster than light and slower than light would violate causality, and is therefore impossible, so if there is anything faster (eg. tachyons) they are effectively not in our universe, as they can in no way possibly effect anything in the known universe. Philc TECI 11:07, 8 May 2006 (UTC)
As I understand the theory of relativity it doesn't say that nothing can travel faster than the speed of light it says that nothing can accelerate to a speed faster than that of light. I don't know who but I've heard at least one reputable physisist has theorised about the possibility of traveling faster than light without accelerating beyond it. AllanHainey 15:39, 8 May 2006 (UTC)
Hmm, this is the third time I've brought up Cherenkov radiation in a discussion like this in a week. Maybe we ought to make a Reference Desk FAQ to save answering the same few questions over and over. GeeJo (t)(c) • 18:37, 8 May 2006 (UTC)
You mean, like a resource where people can look up information that they might be interested in? A searchable database of the communal knowledge of contributers to answer their questions? Skittle 09:34, 9 May 2006 (UTC)
As if by magic, there already is one! :) — QuantumEleven 14:52, 9 May 2006 (UTC)
Who'd have thought people would act so quickly on my idea? : ) Skittle 15:15, 9 May 2006 (UTC)
I take objection to "We know it's the fastest because the mathematics say so". Please remember that both newtonion physics and relativity are simply equations that fitted the facts known at the time to the level of accuracy that could be measured at the time. All mathematics does is tell us that *IF* one thing is true another thing is also true. It CANNOT tell us outright that a statement about the real world is true. Einstein himself summed this up nicely with "As far as the laws of mathematics refer to reality, they are not certain; and as far as they are certain, they do not refer to reality." Plugwash 16:33, 9 May 2006 (UTC)
I am surprised that no one has yet mentioned the implications of Bell's Theorem, which can in many cases be interpreted to violate the local causality assumed in the EPR Paradox. Varied interpretations of this field are many, not least prominent among which is Jack Sarfatti's notions of superluminal travel. On the other hand the most favoured alternative to these considerations are the no-model option chosen by the Copenhagen Interpretation of Quantum Mechanics, and that has its own matters in the Problem of Measurement. So far, even for a maximal theory, Quantum Mechanics is still very much incomplete and one has to be prepared to delve into ever more esoteric speculations, not least because they are absolutely necessary. The problem really rests now upon the conceptions of causality in physics- we are struggling with the possiblity of having to give up the Principle of Local Causes after all. Yet if the Bell's Theorem is taken to be mathematically verified then this must fail, so the only alternative that became available is one that refuses the consider the matter by deeming it pointless- the Copenhagen Interpretation.
On the other hand if the other minor interpretations may be justifiable on some higher ground then superluminal possibilities may indeed be entertained. Or perhaps, like so many other human enigmas, it is simply one in which we will never solve, the beginning of a model which we look to only when other have collapsed or became too clouded.
Finally in another argument I would like to propose that there is a difference between "faster than the speed of light" to "exceeding the speed of light". In order to exceed one first must reach a certain standard, in this case the speed of light, which is a requirement that no bodies known to us may fulfil save the photon. However for a body that is already and always shall be travelling faster than the speed of light, matters may appear very different from a varied perspective. Luthinya 11:50, 15 May 2006 (UTC)

NGV.GAS[edit]

What is the NGV.gas?

Does NGV help? Weregerbil 09:34, 8 May 2006 (UTC)

a duck's quack[edit]

i have heard that a duck's quack does not echo.Is this true?If yes why?

A duck's quack WILL echo. The reason for why this is disputed is because the quack's sound "blends in" sort of with the echo. ALL air waves sent out will hit things in their way. Airwaves WILL bounce back (depending on material and composition), and though losing energy as they go along, WILL be heard as echoes.
A ducks quack diminishes at the same rate as an echo, so it is almost impossible to distinguish the two Philc TECI 11:04, 8 May 2006 (UTC)
This is a myth, and is very hard to differentiate after fairly scientific experimentation as well. -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 11:37, 8 May 2006 (UTC)
Look at the duck article where it links to snopes.com. The scientific experiment didn't seeem that hard to me. --KJ 11:54, 8 May 2006 (UTC)

Microwave data transmission[edit]

Just "suppose" I want to transmit 10 Mbit/sec of data across, say 30km of line of sight at microwave frequencies. First, what bandwidth of spectrum would I need? Secondly, what is the typical cost for receiver/transmitter/microwave dish/etc for the pair that are needed (one each end), excluding any masts and installation. Thank you.

I'm no expert in communications technology, but roughly speaking the bandwidth is going to be of similar order of magnitude as the data rate, and I guess probably a bit more to allow for some of the high-frequency components that you'll get in the sharp edges in your signal, so I guess maybe a few tens of MHz. Arbitrary username 16:10, 8 May 2006 (UTC)
I think it would be usually less than 10 MHz (strictly speaking, depending upon a modulation). I have seen 64QAM and 128QAM being used in radio relay links, in this case the bandwidth would be just about a few MHz. But, again, it strongly depends on modulation. --Ring0 22:25, 8 May 2006 (UTC)
The absoloute minimum needed comes down to signal to noise ratio (see shannon limit) and that comes down to distance and effective radiated power. In reality the bandwidth needed would be higher as no modulation scheme is perfect. Also i think you'd need quite a tall mast as microwave is largely line of sight. If you are seriously interested in this you need someone with practical experiance in whats availible. Plugwash 16:45, 9 May 2006 (UTC)

wierd![edit]

hey 2 all!

In order to understand my question: Rotate your right foot in clockwise direction while sittin.Simultaneously draw the number 6 with your right hand in air.You will find that your foot has changed its direction!

Now my question: Why the hell does this happen?????

Because you rotate your foot. –Mysid 10:42, 8 May 2006 (UTC)
Welcome to Wikipedia, please talk smart next time. It is because your brain is getting mixed up basically. -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 11:36, 8 May 2006 (UTC)

Mac, please Don't bite the newcomers

Anonymous, this is because the brain is conditioned to do things in certain (easy) way. This applies to any new skill you learn (like playing piano, juggling the balls or rotating your parts in the way you discribed). You can overcome this by practicing the act slowly and repeatedly.--Wikicheng 11:54, 8 May 2006 (UTC)

Either I misunderstood the question or I'm a subconscious nitpicker, because it seemed so logical to me why a foot changes its direction while it's being rotated. –Mysid 12:04, 8 May 2006 (UTC)
Oh my goodness, that's cool! Mysid, the question was suggesting that your foot starts tracing a circle in the other direction, ie counter-clockwise. If you trace the circle clockwise and draw the six starting from the top, or trace the circle counter-clockwise and draw starting from the loop, I've found that it really does work (unless you're trying, in which case it's not too hard to do it correctly). It's much like patting your head and rubbing your body, in that it's hard if you're not expecting it, but easy to overcome. Anon, I have can't give a precise reason, but whatever it is, it's cool! — Asbestos | Talk (RFC) 12:11, 8 May 2006 (UTC)
Ah yes, the direction of rotation. :) Thanks and sorry. It really is weird... –Mysid 12:36, 8 May 2006 (UTC)
Yes the brain cannot concentrate on the two movements at once, which is where it asks the cerebellum and basal ganglia for help to automate part of the movements. This is called motor learning, and it takes practice. Some combinations of limb movements are learnt from a very young age, but when you think up a new one (such as writing, driving a car, or combining clockwise-foot and anticlockwise-hand movements) it takes some time for your brain and cerebellum to get it right. As suggested by Wikichen, if you try very slowly, maybe first just the foot movement, and gradually increase the pace, you will eventually manage to maintain your clockwise foot rotation while drawing what you want with your hand. Impress your friends and neighbours!--Seejyb 12:32, 8 May 2006 (UTC)
This trick is described on page 9 of the the classical book of our childhood: Grätzer József, SICC, Móra Ferenc könyvkiadó, Budapest, 1964. – b_jonas 18:15, 8 May 2006 (UTC)

Is it just me, or is this exactly like a question that was asked a really long time ago[23]? Black Carrot 23:28, 8 May 2006 (UTC)

Maybe the questioner meant, "Hey everyone, rotate your right foot a clockwise direction. Simultaneously, with your right hand, copy and past the same question you've already asked into Wikipedia. Get the same reponses. Why does this happen?" --Kainaw (talk) 23:58, 8 May 2006 (UTC)

science[edit]

who is the giant spagetti monster god

Chef Boy-R-Dee?
Flying spaghetti monster. Isopropyl 13:07, 8 May 2006 (UTC)

Collapse of Wave function[edit]

When we observe stuff the wave function collapses but why?

The dynamical evolution of the wavefunction requires that a state with definite value of some observable will eventually evolve into a state which is in a superposition of values (unless it's a stationary state). On the other hand, experience with measurement tells you that if you measure something to have a value, it definitely has that value. If you measure something twice in rapid succession, then you should see the same value twice. Therefore, measurement must change the wavefunction from a dispersed state (which is in a superposition state of different values) to a sharp state with a definite value of your observable. -lethe talk + 14:49, 8 May 2006 (UTC)
Not nessesarily, see þis. *Max* 21:45, 8 May 2006 (UTC)
That's just one of the popular interpretations of QM. There are also others that do better to avoid the Problem of Measurement. Luthinya 11:55, 15 May 2006 (UTC)

Dell Dimension and Pinnalce PCTV does not work properly together[edit]

I recently bought a new Dell Dimension 9150 and it works great, except for one problem: my TV tuner card (Pinnacle PCTV 310i DVB-T) is able to scan for channels, but no channels are ever found. I am quite sure that this is some kind of incompatibility between the PC and the card, because the card worked properly in my previous PC. Any suggestions on how to solve the problem? I have search the Internet, and it appears to a be quite common problem. Thanks in advance. --Andreas Rejbrand 15:27, 8 May 2006 (UTC)

If it is such a common problem, why are there no answers? Perhaps you should try asking a Dell tech support representativevs. That's what they are there for. You can find their main support page here. You can also chat with hardware support reps or visit the Dell forums. --Chris
Hardware Support Chat would be great, but I am not allowed to use it as I live outside the US (in Sweden), and I've already tried to ask the question in the Dell Forums. I thought that someone here might have encountered the same problem. --Andreas Rejbrand 16:01, 8 May 2006 (UTC)

Radioactivity at Chernobyl[edit]

The Prypiat, Ukraine article claims that it "will take up to 900 years to decay sufficiently to render the area safe" while the Chernobyl disaster article says "rendered land in a radius of hundreds of miles from the plant uninhabitable for at least 100 years." Both are unsourced and many similar unsourced claims appear on Google. Which is correct? How long will it take for the more contaminated areas (excluding the plant itself) to get back to about background levels? Cesium is the major radiation source and has a half life of 30 years, so in 900 years, only 1/10,000,000th of 1% would remain. The map in the disaster article shows the most contaminated areas at "greater than 40 curies per square kilometer" and the background radiation article says that average it is about 2.5 mSv, but there seems to be no way to compare those numbers. Rmhermen 15:42, 8 May 2006 (UTC)

It seems that the article on the radio-active isotope, Caesium-137, has a half-life of thirty years... Kilo-Lima|(talk) 20:20, 8 May 2006 (UTC)
Its quite hard to calculate. If all the radioactivity other than prior background was due to one element and that element decayed into a non radioactive element and didn't activate anything else then the time taken for radiation levels to drop to twice background (e.g. the point at which natural radiation would start dominating contaimination) would be (log2current/background)*half life (assuming current and background are in the same units). In reality the dominant isotope will change over the years and there are decay chains and activations of elements hit by radiation to consider. Unfortunately one of your figures is actual radiation and the other is a biological radiation effect figure so they aren't directly comparable. Plugwash 17:02, 9 May 2006 (UTC)

Reaction Types[edit]

Are ther eany types of chemical reactions that are not redox reactions? They teach about redox reactions as if they are special, but I can't think of any reactions that aren't redoxes. Maybe I'm not thinking hard enough?--Chris 15:37, 8 May 2006 (UTC)

If I am not mistaken, the
H + H → H2
reaction is not a redox reaction. --Andreas Rejbrand 16:06, 8 May 2006 (UTC)
There are plenty. (and more conventional than above) E.g., the classical textbook SN2:
CH3Br + OH- --> CH3OH + Br-. Indeed, all substitution and condensation reactions, among many others. --BluePlatypus 16:25, 8 May 2006 (UTC)

I Verify the above; while there may be some exceptions,substitution and condensation reactions are not redox reactions. --Craiglen 16:42, 8 May 2006 (UTC)

A variety of other types of reactions can be found at chemical reaction, or you can look at Category:Chemical reactions for many more examples. --Ed (Edgar181) 16:48, 8 May 2006 (UTC)

Acid-base reactions--usually studied in general chemistry classes before redox reactions--are not redox reactions. Chuck 19:42, 8 May 2006 (UTC)

Birds[edit]

Do all birds lay eggs? I seem to remember from my college orinthology course that there are some species of birds that do not lay eggs? I got $5 riding on this with a friend so if you can prove him wrong. Even if you have to stretch the "truth" a little, that'd be grrrreat.

Depending on how hard you're willing to bend the truth, male birds don't lay eggs :P -- Ferkelparade π 16:27, 8 May 2006 (UTC)
None of the readily available sources seem to cast doubt that all birds lay eggs. I seem to recall this debate in the past, and that there was a type of bird that essentially produced an egg but it hatched internally so the young exited the body without it... but i don't remember any of the sources for that so it may have been a delusion. There are a few sites that attest to egg laying as a critical feature of birds, and our article on birds has this to say: "Common characteristics of birds include... the laying of hard-shelled eggs". Hope this was the answer you were looking for! --Jmeden2000 18:12, 8 May 2006 (UTC)
Continuing to bend the truth, there's jail-bird, whirlybird, yardbird... --Shantavira 18:51, 8 May 2006 (UTC)
Maybe you are confusing birds with fish. I was always told that all fish laid eggs. Then, I found out that there is some type of fish called Molly (or something similar) that doesn't lay eggs. --Kainaw (talk) 23:59, 8 May 2006 (UTC)
Not all sharks lay eggs either. But again, that's fish not birds. Grutness...wha? 01:30, 9 May 2006 (UTC)
The term is "ovoviviparous", but a search for "ovoviviparous birds" gives me nothing. --KJ 00:24, 9 May 2006 (UTC)
Neither does "avian ovoviviparity". --KJ 00:29, 9 May 2006 (UTC)

Maybe there's a kind of bird that doesn't lay eggs, it just merely excretes them, or perhaps shoots them out at high velocity.  freshgavinΓΛĿЌ  04:22, 9 May 2006 (UTC)

The article egg (biology) claims that "This is the reproductive way of many fish, amphibians and reptiles, all birds, the monotremes, and most insects and arachnids." However, I wonder if there exists some kind of "mule" bird that is sterile and thus cannot lay an egg. – b_jonas 17:13, 9 May 2006 (UTC)
Such birds occur (hybrids or domestic breeds - indeed the "mule duck" bears its name due to the fact; it's a Musk Duck x domestic duck hybrid that is sterile). But they are no evolutionary lineage and have to be "made" anew every generation.
There are one or two papers on the topic, and I will shortly reference one under Hesperornithes. Suffice to say that no known birds are (ovo)viviparous, that the parameters which could entice some bird lineage to evolve such a trait have been circumscribed (large size, flightless and/or marine, one or two offspring per clutch and low body temperature), and that Hesperornis is the most likely candidate for an (ovo)viviparous bird though it's still far more likely than not that they laid normal eggs. Dysmorodrepanis 03:58, 28 December 2006 (UTC)
If there was a bird that shot eggs out at high velocity, wouldn't they be liable to break, and therefore defeat the purpose of laying them? -- Filliam H Muffman 03:55, 10 May 2006 (UTC)
I imagine it would be a freak survival-of-the-fittest kind of thing, where the baby birds that learn to fly after "houdini-ing" out of the egg and before smacking into a wall survive, and those that doze off die before knowing that anything else ever existed.  freshgavinΓΛĿЌ  06:55, 10 May 2006 (UTC)
That's a nature documentary I'd like to see. -- Filliam H Muffman 02:55, 11 May 2006 (UTC)
Lol – b_jonas 20:04, 11 May 2006 (UTC)

CT scan visuals?[edit]

Kind of a weird one here...the other day I went for a CT scan of my sinuses, and during the procedure I saw strange blue lines moving up and down my vision (eyes closed). Of course I was supposed to keep still, but the appearance of these startled me, and I wondered...if these are seen by many people, why don't they warn the patient? If they aren't seen by many people, what's different about me? --Kickstart70-T-C 17:21, 8 May 2006 (UTC)

See X-ray#Visibility to the Human Eye. —Ilmari Karonen (talk) 17:41, 8 May 2006 (UTC)
The scanner has a "targeting" line of light (usually red) which indicates to the operator what plane (transverse "cut") of the body is being scanned. As your head moved through the scanner, with sequential planes being scanned, the line of light moved down over your face. I agree about the need to tell the person being examined. I wonder though, why you experienced the light as blue - any chance of your having royal blood in your eyelids? --Seejyb 20:51, 8 May 2006 (UTC)
I'm pretty sure Ilmari Karonen has it...the lights weren't following a linear path (top to bottom or vice versa)...they were stripes of light that appeared in multiple lines at once. And now I can claim I can see x-rays :) --Kickstart70-T-C 05:55, 9 May 2006 (UTC)
Your experience asks for some looking into: Why blue light? Why the pattern not corresponding to external visible beams? As you say: Do more people experience this? If so, what do they describe? Maybe you can draw up a short questionnaire for persons having head scans at your local radiologists (to be answered afterwards!) - if you find others with similar experience, take it further. --Seejyb 07:42, 9 May 2006 (UTC)

Diesel-hybrid engines in cars?[edit]

Diesel engines have been hybridized with electric engines in trains, why haven't car manufactures spent money in putting the efficient diesel-hybrid engine technology into cars?

1. Wouldn't the diesel aspect gives cars the ability to be manufactured for biodiesel, therefore using a renewable resources?

2. diesel engines work on compression and therefore theoretically can last longer, right?

3. hybridizing this with an electric engine would create a relatively clean engine that runs on renewable resources, wouldn't this be a smarter alternative to today's engines?

Um, they are. :) Hybrid vehicle
Yeh they are, but it doesn't work, because all the energy used to move the huge battery discounts any saved by it being hybrid.... Philc TECI 22:21, 8 May 2006 (UTC)

Diesel Hybrid Engines[edit]

Why is it that car manufactures haven't built a car around a biodesiel-electric hybrid engine?

This type of engine (diesel-electric hybrid) has been used in trains for almost a centuary, it's efficient and robust, provides a lot of power (it drove trains) and it would use renewable resources...

-- Stewart Alexander --

Sweden is currently focusing heavily on biodiesel. This resource is rather renewable, and I don't think el-hybrids will be seen until a few years ahead, at least a decade. After all, you have to create a market for the normal car before you can sell hybrids.
Biodiesel is simply a fuel used in ordinary diesel engines - no new cars have to be developed to use it and Europe has a rather large market for diesel cars already, unlike the U.S. Rmhermen 20:02, 8 May 2006 (UTC)

A gas hybrid saves 20% in the city, and almost nothing on the highway (air resistance dominates). Current diesels already exceed that, but are dirty (I saw a brand new Jetta TDI belching!). New low-sulphur diesels should be much cleaner, so right now, a diesel hybrid doesn't make much sense. --Zeizmic 21:37, 8 May 2006 (UTC)

The diesel-electric Opel Astra should be coming out this year. The European diesels put out very little exhaust fumes. The car can apparently do 1-100 km/h in 8 seconds, and gets 60 mpg (claimed 25% better than diesel alone?). The advantage of hybrids is in short distances. See [hybridcars.com]. I personally like the idea of using butanol as a sustainable biofuel. --Seejyb 22:22, 8 May 2006 (UTC)
Hybrids cars don't work, they waste more energy than normal cars, as the battery adds so much weight to the car, scientists don't think hybrid cars will be worth the difference until a viable way of storing a lot of electricity in a small space is cracked, the current hopes lie in the hydrogen cell. Philc TECI 22:24, 8 May 2006 (UTC)
Phil, you're flat-out wrong. Hybrids are more fuel-efficient than normal cars in urban areas because a) they "recycle" some of the energy normally lost in heat when you put your foot on the brake into charging the batteries, and b) they don't waste fuel at idle in traffic; it's either used to recharge the battery or turned off. It doesn't work quite as well as the EPA mileage statistics would indicate, mind you, but it does work, and it does overcome the costs of the extra weight. The same principles also work fine with diesel engines as well.
One thing that needs to be appreciated with regards to diesel is that it's a much denser fuel than gasoline; a liter of diesel weighs about 15% more than petrol, contains about 18% more energy when burned, and releases about 18% more carbon dioxide. So, in terms of carbon emissions, the difference between diesel and gasoline is less than you might think by reading the raw fuel consumption figures.
Fuel cell vehicles will probably use most of the same tricks as hybrids to improve their efficiency, by the way; they will already have the electric motors so all they need is some batteries or supercapacitors to act as temporary storage. --Robert Merkel 23:47, 8 May 2006 (UTC)
"Hybrids are more fuel-efficient than normal cars in urban areas", I'll concede that, apologies, I should have specified. Though the battery weight is an issue, if you spend alot of time running solely off of the engine, and also I think you would be surprised how incredibly low the petrol consumption of a car in nuetral is, so when you stop in traffic, if you put it in neutral you'll save fuel. Also I dont know why they dont use the brakes to recharge the batteries in all cars, this isn't really something limmited to hybrids, although it is easier with them, already havein electric motors attached. Philc TECI 21:00, 9 May 2006 (UTC)

Visual Basic .NET[edit]

I need some help from someone good with Visual Basic.NET edition, as I learned to program in VB6, and I'm having a couple of problems with my .NET coursework project, and as usual trying to get a relevant answer out of MSDN is like trying to squeeze water from a stone.

You'll need to state what mechanism you're using to write the file. If it's something that's meant to "save" or serialize program data more-or-less automatically, there's probably a corresponding read function that will need, use, and strip the "s for you. --Tardis 17:39, 9 May 2006 (UTC)


Sorry, I've changed it a little today. I'm currently just using the PrintLine function to write the data to a .txt file:
PrintLine(1, txtIDNumber.Text, ",", txtSurname.Text, ",", txtForename.Text, ",")
I changed to that from WriteLine earlier, which was surrounding every individual string with quotes. PrintLine is not doing this. But the LineInput for reading text from the file seems to be placing quotes around the entire line feed:
"123, Smith, John"
Thats using the code (this is from my delete record sub):
Do While Not EOF(1)
    lineoftext = ""
    lineoftext = LineInput(1)
*   textarray = Split(lineoftext, ",")
    If textarray(0) <> txtIDNo.Text Then
        PrintLine(2, lineoftext(1))
    End If
Loop
All this does is read a line from the record (lineoftext = LineInput(1)), split the line into individual strings, and assign it all into an array (textarray). However, when I place a breakpoint at the * line, lineoftext's value is "123, Smith, John"
The If statement is getting confused as a result, as it is recieving the value "123 which of course does not match with 123.
Thanks for your help, CaptainVindaloo 19:31, 9 May 2006 (UTC)
Ok, got it all working now. CaptainVindaloo 18:11, 10 May 2006 (UTC)

Alternative life forms?[edit]

Is it possible that organisms could live with an element rather than carbon, i.e. silicon? Could it work hypothetically?


Thanks!

Ooh, we've got a lot of material on this question! See Alternative biochemistry and, for silicon, Silicon#Silicon-based life. Melchoir 19:56, 8 May 2006 (UTC)
[24] might also interest you. --Chapuisat 19:59, 8 May 2006 (UTC)

AHa, thanks for that :D

I recall being told that it is possible, but would recquire a radically different atmosphere, as C02, on which so much of the life on this planet depends on is a gas, however silicon dioxide, is sand, which is less easy to breathe. So hypothetically yeh, but then shouldn't everything in group IV be the same... Philc TECI 22:27, 8 May 2006 (UTC)
Unfortunately, the problems for silicon go a lot deeper than that; check out the articles. Melchoir 01:37, 9 May 2006 (UTC)
Isaac Asimov had a short writing on why carbon is the most suitable element for this form of life. I don't know its title. – b_jonas 16:14, 9 May 2006 (UTC)
If carbon is the only element that's able to form molecules neccessary for life, we could still ask whether it has to be the same molecules as we have, such as proteins built from the same 20 amino acids we have, and nucleic acids etc? If life would possibly exist based on different carbon-based molecules, I belive it would also be completely incompatible with ours, for example, we couldn't live on food made from such beings. – b_jonas 18:29, 9 May 2006 (UTC)

DSN in artic/antartica[edit]

i was thinking how much of an advantage/disadvanatges would there be to putting communication telescopes (like the deep space network) in the artic/anartica? i mean all the equipment will be kept cold easily, your a long way away from any man made sources of interfernce and u could in theory point the telescope in any direction, are there any other things i missed? and what problems are there?

Read Antarctica and find out why only penguins live there. --Zeizmic 21:33, 8 May 2006 (UTC)
Logistic problems and technocal problems with the dish aside, the ecliptic would be too close to the horizon. It is extremely expensive to shoot a spacecraft in an orbit inclined to the ecliptic, this has been done once and required a gravity assist from Jupiter. Besides, most spacecraft are shot to planets anyway. So for all practical purposes the antenna would be useless.

If you want a neutrino telescope that requires a mile of ice for detection, then Antarctica would be a good place to build it. Which is why our neutrino telescope is in Antarctica. -lethe talk + 03:29, 9 May 2006 (UTC)

IP Address[edit]

If I know someone's IP Adress how do I find out who it is? Someone insulted my friend and all I have is their IP Address. Þanks *Max* 21:25, 8 May 2006 (UTC)

You can't. So put away your ideas of keying their Rolls. --Zeizmic 21:31, 8 May 2006 (UTC)
(once again, Zeismic beats me to it) Usually it's impossible - IPs for private computers are assigned by the user's internet service provider (ISP), and some even use dynamic IPs (ie your IP changes every time you log on). At most you'll be able to get the name of the ISP, and maybe the town/city. It's different if the IP belongs to a website, in which case, you'll be able to get the name/company it's registered to. The tool you need is called a whois, I always use the one at DNSStuff.com, and it works pretty well. Try it, you may get lucky. — QuantumEleven 21:35, 8 May 2006 (UTC)
The ISP can technically trace that IP in their records. You're welcome to call and ask them to reveal the culprit, but unless you're the FBI you have nil chance. - Draeco 03:23, 9 May 2006 (UTC)
It's pretty much guaranteed that the person that insulted your friend knows your friend, and there's a very good chance that they are in close contact. Considering that the person managed to contact your friend via the internet, an easy first step would be to check the IP against people in your friend's instant messanger lists (if they use one/them). It's not possible for all programs, but in general there's hacks for things like ICQ (and I'm pretty sure messenger has one that works too) that will reveal their IP for you. Just don't do anything stupid with it.  freshgavinΓΛĿЌ  04:17, 9 May 2006 (UTC)

HIV & blood transfusions[edit]

Do hospitals give people who already have HIV/AIDS blood from other HIV positive people? A Clown in the Dark 22:39, 8 May 2006 (UTC)

Doubt it as having aids, means you can't fight off any diseases, so someone with Aids probably also has just about every other disease they can get, so they would just be needlessly infecting already weak people with more viruses and illnesses. Philc TECI 22:45, 8 May 2006 (UTC)
No, hospitals don't intentionally give anyone HIV positive blood. HIV-positive people are asked not to donate blood, and any donated blood that tests positive for HIV is discarded. - Nunh-huh 23:00, 8 May 2006 (UTC)
To explain Nunh-huh's comment, the number of extra potential donors would be pretty small outside sub-Saharan Africa. Furthermore, as I understand it one person's HIV virus might not be the same as another person's - it might be resistant to a different set of antivirals - so infecting somebody who already has one batch of HIV with another might not be as harmless as you think. The very marginal benefits to the blood supply, which could only be given to a very small fraction of the population, wouldn't be worth the downsides. --Robert Merkel 23:34, 8 May 2006 (UTC)
Short answer: no. Longer answer: Robert Merkel is correct; there are a number of different strains of HIV. (Our article has the details.) This figure shows a 'tree' relating the different known strains of HIV; shorter branches link the more closely-related strains.
If you infect an individual with more than one strain of HIV, you can have (at least) two Bad Things happen. First, different strains may respond differently to a given patient's immune system and medications; trying to treat both virus strains is more difficult than finding drugs that control one strain. Second, the two viruses can swap genetic material – viruses are promiscuous little buggers – potentially resulting in a new strain that's nastier than either one by itself. This has obvious negative consequences for the patient; it also exposes the rest of society to (potentially) another more virulent and/or more drug-resistant strain.
There's also the consideration that collecting blood from HIV-positive donors would put the nurses and technicians involved in the collection, testing, transport, and delivery at additional risk. TenOfAllTrades(talk) 03:06, 9 May 2006 (UTC)

If I remember correctly, in And The Band Played On, it states that blood banks generally love lesbians, because they tend to have the cleanest blood (esbians almost never contract blood-born STDs). Raul654 03:10, 9 May 2006 (UTC)

May 9[edit]

Diesel-hybrid engines in any vehicle? Why not a quasiturbine-hybrid instead?[edit]

All the quasiturbine needs is an improved method of lubrication so that it will survive for more than 24 hours and according to its inventors its efficiency and capacity to use alternative fuels will be so high that the price of gasoline will plummet so low that there won't even be a reason for building gasoline pumps with meters. -- PCE 00:05, 9 May 2006 (UTC)

Sounds like a mild exaggeration, to say the least. According to the article and pistonless rotary engine, a functioning internal combustion version has not yet been demonstrated, and even if it were it sounds unlikely that it would offer such a revolutionary improvement in efficiency over the Wankel engine that people would abandon the 100-year-established internal combusion petrol/diesel engines en masse in its favour. What 'alternative fuels' would it run on that would warrant mothballing the massive petroleum industry? --Yummifruitbat 00:30, 9 May 2006 (UTC)
The inventor's web site (www.quasiturbine.com) claims that the quasi meets some 14 points that no other engine can (weight to power ratio, etc.) I think fuel types is one of them. The biggest fuel advantage is supposed to be its ability to be configured for photo detonation such that it can run extremely efficiently on hydrogen fuel but short of running on tar it is suppose to be able to hand even high viscosity oils - but most certainly 100% ethanol. -- PCE 00:41, 9 May 2006 (UTC)
I don't know what prompted this question, but you can't beat the Carnot cycle - the maximum possible efficiency is listed in the heat engine article. That gets you maybe a factor of two in basic efficiency over present-day piston engines, if I remember rightly. That doesn't go close to making oil too cheap to meter, particularly as what will happen is that most people would buy more powerful, heaver, and more accelerative cars to take advantage of the improved economy (see Jevon's paradox).
Furthermore, there have been all manner of alternative engine designs over the years, many resembling the quasiturbine. The Orbital engine was an example that was quite famous in Australia. None of them has been made to work much better than a piston engine. --Robert Merkel 08:03, 9 May 2006 (UTC)

Electrical generators - where do they get the magnets from?[edit]

Hi You must have a large coil of wires moving through a magnetic field, which could be normal magnets or produced from electromagnets. In large scale (power plant generators) - does each generator have a Huge magnet built in or do they have electromagnets? if the later is the case where did they get the electricity from in the first place - isn't this a case of catch22?

The electrical generator article says rotors can be powered by a separate turbine/engine. --KJ 01:33, 9 May 2006 (UTC)

If I remember correctly, to start with, they use the permanent magnets of low strength to generate some electricity. A part of this electricity is used to power the electromagnets, thereby increasing the magnetic field and hence the generated current. This goes on till a balance is reached. Please note that this is a kind of negative feedback and hence has to reach a atable state.-- Wikicheng 08:08, 9 May 2006 (UTC)

Also, this is why they price electricity differently if you buy it at low peak. As you can imagine, start-up of a large electric generator is a big deal, so it is better to keep it going as steadily as possible, continuously. This means that if you're going to produce enough power for people at peak times, you have to produce too much at other times even if nobody will buy it. Skittle 09:23, 9 May 2006 (UTC)

Its not the generator that can't increase and decrease power easilly (it can) its whatevers feeding it. IIRC nukes tend to be the hardest to ramp up and down the power on. Coal afaict isn't that hard but is so cheap its usually kept running anway. Gas turbines and hydroelectric dams are the best at varying power. The main reason electricity is cheaper at night is that comes from plants that are cheap to keep running (coal and nuclear) and moving demand to the night reduces the total installed capacity needed.
As for startup there are a number of catch 22's in starting a big plant without electricity. I belive they solve this with dedicated deisel generator units in certain plants to allow a cold start of the grid if absoloutely nessacery. Plugwash 17:09, 9 May 2006 (UTC)
Live and learn :-) Skittle 19:57, 9 May 2006 (UTC)
There's some interesting stuff about this sort of thing in Black start. --Saxsux 19:09, 10 May 2006 (UTC)
A minor aside—cold-starting a coal plant takes about a day, so utilities tend to fire them up when they will be running for at least a moderately-long time. Unfortunately, the highest-demand periods for most utilities are in the summer, when the smog from coal-fired generators is least welcome. Oil-fired boilers take a few hours to bring up; natural gas is used for peak capacity because it can be brought online in a few minutes. TenOfAllTrades(talk) 03:21, 16 May 2006 (UTC)

Typically I'd think its a permanent magnet. Likely a simple hard ferromagnet dug out of the Earth, it wouldn't be an electromagnet because if you think about it, if you could use the electromagnet to power a generator, then simply feeding the electricity back into the generator would produce more electricity -- violation of entropy and the conservation of energy. Soltans 23:07, 15 May 2006 (EST)

evolution[edit]

Greeting Wikipedia -

What is "ecosystem evolution" ? What evolutionary / game - theoritic mechanisms or principles apply ? What book describes the evolution of ecosystems ?

Thank you, Willie

I don't feel confident enough to answer your quesiton outright, but Paul A Selden's "Evolution of Fossil Ecosystems [25] is a recent work on the subject. You're going to find the best treatments in the area of paleontology, because the process is such a long one. - Draeco 03:16, 9 May 2006 (UTC)
"evolution of ecosystems" Try Into the Cool: Energy Flow, Thermodynamics , and Life Eric D. Schneider and Dorion Sagan, U Chicago Press, 2005, ISBN 022673936-8 and references therein. Like: Hutchinson The Ecological Theater and Evolutionary Play 1965. Key concept : Succession of dominance of different species. Ends up in "Climax community" and maximal use of energy flow through the system. see Ecological succession --GangofOne 00:14, 10 May 2006 (UTC)
Thanks for the advice.  - Willie

WiFi Going Insane[edit]

Hey. I'm currently on a 802.11g Wireless Network. My computer connects to a router that has a cable modem plugged into it. Every so often, my wireless network connection will still show 'connected', but all network traffic will stop working (including intranet file sharing, local apache servers, internet, etc.). The only way i can fix this is to 'repair' it in Windows (right-click on the icon in the tray and click 'repair'). What in the world is going on, and how can I fix this (and if I can't fix it easily, how can I get my internet working without having to click repair?). It's happening multiple times a day, and it's getting annoying. — Ilyanep (Talk) 01:58, 9 May 2006 (UTC)

  • What kind of router is it? Wireless routers are notorious for often going on the fritz and refusing to handle packets for no good reason whatsoever, so it would be worth checking if other users of the same model report a similar problem. --Fastfission 02:36, 9 May 2006 (UTC)
  • It happened with my current D-Link router, but it used to happen with my old Netgear 802.11b router as well (although much less frequently). Not sure on the model numbers for either. — Ilyanep (Talk) 02:59, 9 May 2006 (UTC)

Could be classic Windows Spyware Router Choke. --Zeizmic 11:48, 9 May 2006 (UTC)

This is an extremely common problem. I've always suspected it had to do with rotating the security keys. But, I haven't looked into it much because I get rid of all that. On the router, I look at the logs and I find the MAC for the laptop that I'm using. Then, I set up the router to use absolutely no key security. Instead, I tell it to only allow the MAC of the laptop I want to use (most routers let you add at least 16 MACs if you have more computers). Then, the problem goes away. --Kainaw (talk) 14:32, 9 May 2006 (UTC)
Another possible cause: have you checked your cable modem? Some models (my ADSL modem does this) occasionally update themselves while connected, and during this time, all connections stop for a time (one or two minutes), then come back on automatically. Just a thought. — QuantumEleven 14:36, 9 May 2006 (UTC)

Something similar used to happen with mine, before I upgraded to SP2. Theres an article about it here, with some possible workarounds. There might be some other useful stuff here as well. Hope it helps. CaptainVindaloo 16:56, 9 May 2006 (UTC)

"Then, I set up the router to use absolutely no key security. Instead, I tell it to only allow the MAC of the laptop"
right so all the attacker needs to do is sniff your mac and set it on his machine (not sure how well wi-fi will handle multiple instances of the same mac but if it doesn't handle it well he can always wait for you to turn your laptop off). Not that WEP is really that much better if the attacker has some time on his hands. Plugwash 17:17, 9 May 2006 (UTC)
If a hacker can detect your card's MAC and fake it on his card, he will have no trouble faking your keyset. --Kainaw (talk) 19:59, 9 May 2006 (UTC)

I use both a WEP key and 'only allow trusted MAC addresses'. Plus, I'm pretty sure it's not my modem since only repairing the wireless connection in windows seems to fix it (and the internet works on the other computers meanwhile). I'll check out the links that captainVindaloo posted shortly. They appear to be for pre-SP2 and I have SP2. Thanks for the help and let's hope it works. — Ilyanep (Talk) 20:30, 9 May 2006 (UTC)

Also, Spyware can do that? I'll run a scan but i don't think there was anything on my PC. — Ilyanep (Talk) 20:31, 9 May 2006 (UTC)

Have you tried turning off the WEP key? That is what I had to do to stop the constant connection failure in XP. --Kainaw (talk) 20:45, 9 May 2006 (UTC)
I'd really rather not :(. — Ilyanep (Talk) 21:26, 9 May 2006 (UTC)
I don't think you understand what I'm saying... Turn off the WEP key. If everything works great, then you know what the problem is. If you don't turn off the WEP key, you'll never know if it is the WEP key, DNS problems, bad cable, radar interference, positioning of the planets... Once you find out it is the WEP key, you can work on a solution for the problem.
As for the "security" of the WEP key - it should not be used to protect your computer. It protects your network. It keeps others from using your wireless network. Since your router is also a firewall, keeping computers off your network isn't only an issue of bandwidth, it is a security issue. If you don't have protection on your computer and you are depending on the router to protect it, you are begging for trouble. All in all, if you use your laptop in any public location (like a coffee shop), you have abandoned your router's firewall and you are open to attacks again. So, when it comes down to it, the WEP key is just there to protect your bandwidth. Obviously, your bandwidth isn't an issue because you are losing network connection on a regular basis, which is a classic problem with Windows XP wireless networking using WEP keys. --Kainaw (talk) 00:36, 10 May 2006 (UTC)
I understand about that, and that's why I run AV and firewall software (and the internet stops working in its absence as well, mind you). If it is the WEP key then what would I possibly do? Disable it? I don't know if I'd like my communications traveling unencrypted across my neighborhood. — Ilyanep (Talk) 01:16, 10 May 2006 (UTC)
If it turns out to be the WEP key, the problem (as it was explained to me) is: There are 4 rotating keys. Each lasts for a preset length of time (2 minutes or so). Windows XP connects fine with the first key. Then, it may fail when the key rotates, it may not. Two minutes later, it may fail on the next rotation, it may not. Eventually, it fails. There are multiple solutions. An obvious one didn't work for me: make all 4 keys the same. It still failed after the first or second rotation. Another one failed for me: increase the time for each key. I bumped it to to 10 minutes - so I could go 10 minutes before losing connection. Not a solution. The one that worked for me was disabling Windows wireless tools and only using the ones that came with my wireless card. But, most laptops come with wireless built-in now, so there's not special card drivers to use. However, I don't want you wasting your time going down that road if it turns out WEP is not the problem. That is why I suggest testing it. --Kainaw (talk) 01:24, 10 May 2006 (UTC)
We only use one WEP key anyways. But, I'll test it out later today. BTW, I use a desktop, but i don't believe that my wifi card came with software. — Ilyanep (Talk) 01:29, 10 May 2006 (UTC)

A couple of points here. WEP uses cryptography which was very poorly planned and as a result is easily breakable. It should therefore, be regarded more or less as a speed bump to attackers, not as a serious barrier to them. WPA (partial 802.11i) and WPA2 (more complete 802.11i) are MUCH better, but not available on all equipment, even with a firmware upgrade. If this is your plight, protest to your vendor... But, good quality crypto is the only possible way of defeating the security leak inherent in all broadcasting methods -- eavesdropping. Only if you force them ot cope with gibberish they can't convert ot something intelligible can anything going either direction be thought even remotely confidential.

Denial of service attacks are relatively easy to manage for 802.11 networks, most especially for Infrastructure mode (ie, when using an Access Point). These have nothing to do with cryptography (WEP, or 802.11i (partial or not)), but rather to do with the underlying management of the medium and with the realities of low power radio communications. Using 802.11a forces a penalty in range (roughly half that of the lower frequency 11b/g) but, by providing more, and less overlapping, channels, removes at least one of the possible denial of service attacks.

Wireless is not, though it can often be used as if, really securable. It remains vulnerable to many attacks, accidental and deliberate, even when observing best practices with high quality gear meeting all appropriate standards.

Wired connections (eg, Cat 5 10/100 Ethernet) with all its problems, has consderable advantages in terms of reduced downtime and invulnerability to many potential attack modes. And it's almost always faster.

Nonetheless, in the situation described, I agree that it seems to have been some oddity of Windows which caused this problem. Use Linux, one of the BDSs, or OS X, instead. There will be difficulties, largely due to lack of vendor support, but the advantages in less mystery in the problems encountered will be more than sufficient offset. And the software, and much of the applications (ie, a worthy equivalent of Office -- OpenOffice) are free. Both in liberty (they're open source) and as in beer (no cost). Avoiding licensing hell is alone worth almost any trouble, in my view. 71.249.12.89 13:29, 12 May 2006 (UTC)

From my experience with Windows, Windows handles WEP encryption very well. So do most recent Linux distros and even my Nintendo DS. WEP is more flawed than WPA, but only because it is a lot simpler, and this simplicity reduces problems.
We should look at what Windows is actually doing when it "repairs" the connection. IIRC, it disables the network adapter, clears the DNS cache, clears some other cache, re-enables the adapter and reconnects to the wireless network. This already seems to point to a possible problem related to the MAC filtering, as the router would detect a client reconnecting, which it identifies with its MAC address. Just a thought. Also, it might be worthwhile to narrow down the source of the problem by using a packet sniffer such as Ethereal. It is possible that you might not see any packets leaving your system, in which case the OS or related wireless hardware is at fault. If the packets are clearly leaving your system, then the router must be dropping the packets for no reason, and the router is at fault. Then again, Ethereal is a bit funny with some types of wireless cards, often not detecting any packets at any time ... but you are most likely fine. Try to find out in more detail how Windows repairs your NIC, you might find the problem there. -- Daverocks (talk) 12:29, 15 May 2006 (UTC)

Physics[edit]

The masses on a pulley are each initally 1.60m above the ground, and the massless frictionless pulley is 4.8 m above theg round. Mass 1, on the left side of the pulley, is 1.2kg, and mass 2 is 3.2 kg. What maximum height does the ligher object reach after the system is reached? don't think I even got the equations right....but here goes...


Σ F = ma
T - FG1 = m1a


Σ F = ma
T - FG2 = -m2a


Then I subtract my equations..

FG2 - FG1 = (m1 + m2)a
a = (3.2 x 9.81 - 1.2 x 9.81 ) / ( 1.2 + 3.2)
      

Then a is equal to:

a = 4.45 m/²

So next I solved for v2, just before m2 hits the ground

v2² = v1² + 2ad
v2² = 0 + 2(4.45)(1.6)
v2 = 3.77 m/s

Next I used 3.77m/s to solve for the distance that m1 is moving up, which is the original question

v2² = v1² + 2ad
d = (v2² - v1²) / 2a
d = (-3.77² - 0²) / 2(-4.45)
d = 1.6 m

That means that object moved 1.6m above the 1.6m, PLUS the 1.6 m that m2 moves. That's a total of 4.8m, but alas, that is not the answer (3.9m). If anyone could point show me what I've done wrong, thanks. C-c-c-c 03:25, 9 May 2006 (UTC)

What does "after the system is reached" mean? —Keenan Pepper 04:49, 9 May 2006 (UTC)
Sorry that should be "released". C-c-c-c 04:53, 9 May 2006 (UTC)
Are you sure you didn't leave something out of the question? I might be misunderstanding you completely but it doesn't seem valid to me.  freshgavinΓΛĿЌ  06:08, 9 May 2006 (UTC)

Well it's a pulley system, and there are two masses. M1 is 1.2kg and M2 is 3.2kg. The moment after second or first mass is added on to the pulley, the heavier one falls down and lifts the lighter one. I'm supposed to calculate that distance. C-c-c-c 06:11, 9 May 2006 (UTC)

Yeah, I get that much. But the way the question is phrased it seems that the answer is simply 1.6, because the system will "release"? when the heavier weight hits the ground, 1.6 meters later. The smaller weight doesn't move twice that distance, it simply moves 1.6m in the opposite direction.  freshgavinΓΛĿЌ  06:19, 9 May 2006 (UTC)
The system is already 1.6m above the ground. I really don't know, I didn't make the question up. The answer in the back is 3.9m for some reason. Any ideas? C-c-c-c 06:23, 9 May 2006 (UTC)
Ah, right. Then I guess we're back at the start, and I'm as confused as you are.  freshgavinΓΛĿЌ  07:10, 9 May 2006 (UTC)

I'm guessing that by "maximum height" the problem means: after the large mass hits the ground, and the small mass rises through 3.2m, the rope will go slack and the small mass will free-fall until it returns back down to 3.2m (at which point the system will continue to oscillate until all the impacts between the big mass and the ground dissipate the energy). During that free-fall, what maximum height does the small mass reach? I wouldn't try to solve any equations of motion, or consider accelerations, forces, or tensions. Just apply energy conservation very carefully. Melchoir 07:30, 9 May 2006 (UTC)

I don't think it's that's complicated because I think this is just supposed to be as straight forward as possible. We haven't done energy conservation yet, this is all based on dynamics. So as the heavy block drops, it just stays there, and there's no dissipating energy. The rope is supposed is not supposed to sag. Am I on the right track with what I have so far? Do you know what I could do next? Thanks a lot. C-c-c-c 07:36, 9 May 2006 (UTC)
If the heavy block is to stay on the ground, then one second it's falling and the next second it's not; this is a loss of kinetic energy. And the rope really does have to go slack if the answer to this question is to be greater than 3.2m; the rope is geometrically incapable of pulling the small block any higher than that! There's only so far the poor thing will go.
As for what you have so far, I can't comment, because I don't understand your strategy. But I'm sure the correct answer will involve less work... Melchoir 07:45, 9 May 2006 (UTC)
Ah, yes, here we go:
1.6\mathrm{m}\left(2+\frac{3.2-1.2}{3.2+1.2}\right)=3.927\mathrm{m}.
That was energy conservation, but I'm sure there's another way to get there. Melchoir 08:03, 9 May 2006 (UTC)


Mhm alright. I'll check with my teacher. Thanks! C-c-c-c 08:16, 9 May 2006 (UTC)

Would this work?: The heavier mass is accelerating downwards for 1.6m. What is its velocity when it reaches the ground? (Aside: Would it be the same as a 2kg mass in free fall?) That downwards velocity would be the same as the upwards velocity of the mass on the other side of the pulley. Now you have a mass going upwards at a known velocity, being decelerated by gravity. How far does that 1.2kg mass go upwards before its velocity becomes zero, slowed down by gravity = maximum height reached?. I guess they are asking for that maximum height (remember the initial 1.6m). --Seejyb 08:28, 9 May 2006 (UTC)
You mean initial 3.2m, right? Melchoir 08:31, 9 May 2006 (UTC)
You're right, the way I stated it ignores the 1.6m acceleration phase, and the answer would be wrong if one did not include that too. --Seejyb 08:38, 9 May 2006 (UTC)

I was thinking too simply and I forgot that you'd be dealing with stuff like slack at that level! Melchoir's solution is obviously correct but it seems like you haven't been taught energy conservation yet, so you can think of it like this: You have the acceleration at the point the system releases (9.81m/s²), you have the velocity at release (3.77m/s up) and at max height (zero).

It's been so long since I've done math in an organized mannar so excuse me for my weird methods of deriving equations. Using the formula for acceleration you get:


\mathbf{\bar{9.81}} = {\mathbf{3.77} - \mathbf{0} \over t}

which gives you to 0.38 seconds.


\mathbf{velocity} = {\mathbf{d} \over t}
, so find the average velocity, and calculate for d:

\mathbf{\bar{3.77 - 0} \over 2} = {\mathbf{d} \over 0.38}

and you get 0.72, which when added to the base 3.20 gives you the same answer (3.92) as Melchoir as well as the text book. I wonder if you understood that O o;;.  freshgavinΓΛĿЌ  06:14, 10 May 2006 (UTC)

Physics II[edit]

Sorry to be a bother again, I just have quick question on solving problems without mass. A box is given a push so that it slides across the floor. How far will it go, given that the coefficient kinetic friction is 0.20 and the push imparts an initial speed of 3.0m/s? I have to figure out the acceleration, then I can use kinematics to get the distance.

So:

FA - Ff = ma
FA - μkFN = ma
FA - μkg = a
FA - 0.20(9.81) = a

I canceled out the masses but now I have two unknowns still. I don't know what to do with FA...I think I may be missing some critical information that I should know but can't seem to have pop up in my head. thanks. C-c-c-c 08:47, 9 May 2006 (UTC)

Admittedly, my physics is a bit rudimentary, but I'm pretty sure you can't cancel those masses out without also doing so with the FA term. I don't quite see how FA - Ff leads to mg, either, since this is dealing with movement on a plane and not freefall... —Zero Gravitas 08:55, 9 May 2006 (UTC)
It's "ma", I made a typo. That's how we dealt with questions that didn't give you a specific mass, you eventually had them cancel out and it wouldn't affect your answer. Not sure here though. C-c-c-c 09:00, 9 May 2006 (UTC)
What is FA supposed to be? Is there some force other than friction affecting the motion? Melchoir 09:04, 9 May 2006 (UTC)


FA is the force of the box being pushed C-c-c-c 09:05, 9 May 2006 (UTC)
During the time period we're interested in, that's zero. Melchoir 09:14, 9 May 2006 (UTC)
You don't need to know anything about how the box reached 3.0 m/s. The point is, it is released at 3.0m/s, then decelerates due to friction until it comes to rest. During deceleration, the only horizontal force on the box is the frictional force μN, where N is the normal force. And N must equal the box's weight, mg, since the floor is horizontal. So the box with (unknown) mass m is being decelerated by a force μmg ... Gandalf61 09:26, 9 May 2006 (UTC)


Oh, I see...it's not affecting it during the sliding... I didn't realiaze that,alright. Mhm yeah I get the acceleration then easily, and the distance too. Thank you Melchoir, and Gandalf61 and Zero Gravitas too. C-c-c-c 09:30, 9 May 2006 (UTC)

Name this tank[edit]

US tanks in the Solomon Islands during WWII

Can anybody tell me what kind of tank is pictured in this photo. Thanks.--Peta 04:41, 9 May 2006 (UTC)

It looks to my untrained eye like an M5 Stuart Raul654 04:48, 9 May 2006 (UTC)
Maybe a Sherman? Though now I'm not so convinced.... C-c-c-c 04:51, 9 May 2006 (UTC)
No, it's clearly not a sherman. The more I look at this pic the more I suspect it is a Stuart. Raul654 04:55, 9 May 2006 (UTC)
This page] has an almost identically staged photo; it's got to be a Stuart. —Zero Gravitas 07:53, 9 May 2006 (UTC)
The document I got the image from just describes them as light tanks.--Peta 05:13, 9 May 2006 (UTC)
Stuart was a light tank, it looks like a Stuart to me, although maybe an early model.

Are autistic-savants child prodigies?[edit]

Are they? a.s.s can't survive on their own while c.p.s can. A.s. can't perform simple tasks like buying gum or estimating if things are expensive, etc.--Jondel 05:10, 9 May 2006 (UTC)

"A prodigy" is simply a person who has an exceptional talent or skill of some kind. That is, one and only one skill is enough. It depends what level of talent you consider prodigaeic, but the destinction between CPS and ASS doesn't apply.  freshgavinΓΛĿЌ  06:05, 9 May 2006 (UTC)

What is this lizard looking thing?[edit]

I took these pics after finding the little guy in the ditch on the side of my road. He's about 2" long and orange with darkish spots. The road is in the Green Mountains of Vermont. I later found quite a few more of these things on the side of the road. Sorry the pics aren't better but I'm not that good of a cameraman. So, what is it? Dismas|(talk) 05:24, 9 May 2006 (UTC)

Maybe a salamander? I seem to remember some types of salamanders making occasional appearances in south-eastern Ontario when I was a kid, so they should be in your area as well. The spots are very common of salamanders too.  freshgavinΓΛĿЌ  06:23, 9 May 2006 (UTC)
Or a gecko? --Shantavira 07:28, 9 May 2006 (UTC)
Definitely looks like a salamander to me, though I can't tell what species it is. — TheKMantalk 08:03, 9 May 2006 (UTC)
Thanks! We'll go with Salamander then. Dismas|(talk) 09:35, 9 May 2006 (UTC)

It is a newt! We have them at our diabetes camp farther south in the Appalachian mountains of Pennsylvania. A newt is an immature salamander still in the land-living stage. They eat small bugs. You can find them in the grass or leaves within a hundred yards or less of a swamp or wet area. They are about 2" long, move slowly and are easy to catch, not slimy. The dominant color of the Pennsylvania ones is a burnt or dusky orange, but they have two parallel rows of bright orange dots ringed with black running down their backs. Beautiful. When they get older the color changes (to black and white I think), they grow to maybe 5 or 6 inches, and they move back into the water and are rarely seen. alteripse 10:50, 9 May 2006 (UTC)

An Eastern Newt to be precise (Newts are in the family Salamandridae, so salamander is correct also). -Wiccan Quagga 14:16, 9 May 2006 (UTC)
Hey! Cool! Thanks, that's exactly what it is! Dismas|(talk) 20:49, 9 May 2006 (UTC)
It's also called a red eft. And eft is a cool word. Word.TheSPY 00:28, 10 May 2006 (UTC)

Cool. Never knew newts were salamanders. Not that I've ever thought hard about it before though!  freshgavinΓΛĿЌ  06:16, 10 May 2006 (UTC)

how do they do it?[edit]

i've always been curious to learn how pros balance a basketball on their fingertips.just exactly how do they do it?

thanks a tonne

They spin it. With a little practice it's not that hard to get it going for a couple seconds. Keeping it going is harder. With the ball in your hand, spin it with your finger tips while tossing it up just a little. Then "catch" the ball on the tip of one of your fingers, usually the index finger works best, right on the axis of the spin. With a little balance, it will keep spinning on your finger tip. Dismas|(talk) 08:26, 9 May 2006 (UTC)

In fact, you can balance the ball even without spinning it (try it !). Spinning stabilises the ball due to gyroscopic effect and makes it easier (in theory). The tough part is to learn the art! Experts balance many other objects like plates too. -- Wikicheng 08:47, 9 May 2006 (UTC)

Titanic's exhaust pipes[edit]

Hi,

In the movie and in pictures of Titanic, the exhaust pipes of the ship seem to be not perfectly vertical but are tilted slightly. Is there a technical reason why it should be ? -- Wikicheng 09:11, 9 May 2006 (UTC)

I'm prety sure it was purely aesthetic. One of the funnels (as they're called) on the Titanic was even a dummy, because it looked better with four than with three. --BluePlatypus 10:15, 9 May 2006 (UTC)
Where was that funnel? Wouldn't be too beautiful with smoke coming out of only three, so it ought to be one of the central ones to cover up. :)
Actually it was the one in the back. Maybe they convinced people it was a spare,though according to our article it did serve as a vent. -Wiccan Quagga 14:08, 9 May 2006 (UTC)
Compare that with the picture at the top of RMS Titanic :-) Artistic license... Weregerbil 16:17, 9 May 2006 (UTC)
Were there any fires reported during the sinking? If so could smoke from them have gone up the rear chimney.
BluePlatypus is correct, the rake of the funnels was purely aesthetic. The fourth funnel in several four-funneled liners was a "dummy" again added for aesthetic reasons, but in Titanic, as the article says, this was not entirely without other function, but housed a ventilation shaft. To answer the question from an unsigned anon, the arrangement of the power plant of the ship (engines abaft the boilers) dictated that the three "real" funnels must be forward. As you can see in her plans, the exhaust flues from the boilers took up a great deal of space internally; there could be no question of avoiding locating the "real" funnels above the boilers. But this would put three funnels awkwardly far foward from the point of view of aesthetics, to the fourth was added to balance out her profile.---CH 10:33, 16 May 2006 (UTC)

Hypothetical engine questions[edit]

2 quick questions:

  1. Would it possible to make a diesel (i.e. compression ignition) Wankel engine? Judging from the article (under Advantages and Disadvantages), it seems the answer might be no.
  2. On a side note, what is the compression ratio of the Renesis engine? How is compression ratio defined for a rotary engine?
  3. Would it be possible to make a diesel engine that runs on petrol? Vice-versa, would it be possible to make a spark ignition engine that runs on diesel?
  4. For all of the above, what are the major disadvantages and/or reasons they would not work? (I'm assuming there must be something fundamentally disadvantageous/impossible about these concepts else we would probably have seen them by now.)

Zunaid 10:19, 9 May 2006 (UTC)

As for a diesel engine that runs on petrol, I think that even if it would be possible, it wouldn't make sense to actually mass-market one, as there's no other advantage of a diesel engine over a normal one other than that the fuel is much cheaper. – b_jonas 16:01, 9 May 2006 (UTC)
2) Compression ratio for a rotary engine would be defined as the ratio between the chamber volume when the fuel intake is cut off, and the minimum chamber volume.
3) A diesel engine that runs on petrol? Sure: see engine knock. The reduced compression ratio means that such an engine wouldn't be as efficient, and diesel fuel has handling advantages (such as reduced fumes) over petrol. It should also be possible to make a spark-ignition engine that runs on diesel, but you'd need some way to encourage the diesel fuel to vaporize (a fuel preheater, perhaps?). --Serie 21:12, 9 May 2006 (UTC)

Brain USE Percentage?[edit]

Hi, I was having a discussion with a few friends and was wondering if anyone had any reputable references in regards to how much of our brain we use. I've heard that we use only 1% of our brains ability. However I've also heard we only use a small percentage at any given time. Others have stated that we use 100% of our brain just that we do not use it all the time, and that with differnt tasks we use different parts of our brain but in the end every part of our brain we use.

The concept is widespread, but originated as marketing hype and is mostly perpetuated by people trying to sell you something you don't have a need for. Think about how silly the concept is by applying it to other organs.
  • At any given moment only 10% of your muscles are working. Get opisthotonus or spasticity so more of them are always contracting!
  • At any given moment only 10% of your retinal photoreceptors are firing: go stand in a nuclear explosion so that nearly 100% will fire!
Anyway, you get the idea. The concept is no more biologically meaningful than the slogan, "why not live life to the fullest", especially when used to market Armpit Kleener or somesuch. alteripse 10:41, 9 May 2006 (UTC)
See also The Ten-Percent Myth at snopes.com. –Mysid 11:05, 9 May 2006 (UTC)
I always thought this myth came from the fact that most of our brain cells are glial cells, not neurons, but snopes.com didn't mention that as a possible origin. --Ginkgo100 18:56, 9 May 2006 (UTC)

Name for a color / paint[edit]

Hi, I've been wondering about what could be the English name for the screaming colors usually used in highlighter pens and police vests. They are usually pink or yellowish green, but can also be orange (see Image:Helsinki fire truck H10.jpg), and often hurt the eyes on a clear day. In Finnish and apparently German they are called "neon colors" but I couldn't find anything similar in the English Wikipedia. –Mysid 11:13, 9 May 2006 (UTC)

A google search for "Neon Color" [26] results in approximately 132 000 pages. Perhaps, it is called "Neon colo(u)rs" in English as well? --Andreas Rejbrand 11:32, 9 May 2006 (UTC)
Yes, "neon colors", such as neon green, are commonly used in American English. --Ed (Edgar181) 11:38, 9 May 2006 (UTC)
Oh okay, thanks. (I found an article on fluorescence but it didn't really refer to the colors anywhere. Maybe there should be an article. :P) –Mysid 11:42, 9 May 2006 (UTC)

When the colors were first widely used in the US in the late 1960s, they were often called DayGlow or Day-Glo. alteripse 11:49, 9 May 2006 (UTC)

As far as their use in art is concerned, they're usually referred to as Fluorescent X, where X is the name of the particular colour (so there's fluorescent green, fluorescent yellow, fluorescent orange, etc). But the term day-glo is also widely heard (X-Ray Spex even had a punk rock song with it in the title :). "fluorescent orange" gets 340,000 google hits, for instance. Grutness...wha? 12:23, 9 May 2006 (UTC)
Quite often in the construction and factory trades in the U.S. the colors will be preceded by the word "safety". Safety yellow is often used to designate barriers and steps while vests and helmets are often safety orange. Dismas|(talk) 13:12, 9 May 2006 (UTC)
Y'mean like Safety orange?  :) User:Zoe|(talk) 18:36, 9 May 2006 (UTC)
Sure, just go the easy route and provide a link.  ;-) Dismas|(talk) 20:48, 9 May 2006 (UTC)

The jackets in these colours are (at least in the UK) called high visibility or hi (gh) vis. I've consequently heard the colours referred to as "high vis(ibility) yellow/orange". Thryduulf 01:01, 10 May 2006 (UTC)

Aren't they louminescent colours? (yes this is incorect use of the term, but it what I've heard) Philc TECI 18:10, 10 May 2006 (UTC)

Any idea what this flat head worm slug thing is?[edit]

I went to take the garbage out and since it rained last night there was a handful of earth worms on my drive way. To get a little good karma I started moving the worms into the grass to ensure the sun or my car doesn't kill them. It turns out one of them wasn't a night crawler though. It had the same body size as a medium sized worm, sticky with a slime trail like a slug, had a flat head it dabbed around and occasionally raised like a snake, and had two brown stripes down it's back. The girlfriend has the camera in her car so I can't take a picture of it. I've never seen one of these before. Anyone know what it could be or know of who I can ask about it?

I don't know much about invertebrates, but I've seen a flatworm on TV once that had some stripes. --KJ 13:25, 9 May 2006 (UTC)
This thing was only flat on it's head. The stripes were ligher brown on brown. I'm almost certian it was a slug becaused when I touched it it retracted itself.
Like this? --Kainaw (talk) 13:46, 9 May 2006 (UTC)
Nope. Tubular body, looked like a regular worm at first. Then I got close and it had a tiny flat shovel head. The head was not antenna like. Focus less on the strips and more on the head.
You mean like this? --Kainaw (talk) 13:53, 9 May 2006 (UTC)
The stripes are much darker and mine was skinnier but that looks like my mystery creature. It even says they are located in Florida. I should of mentioned I live there. Thanks a lot!
Far freaking out. I just saw one of these on a sidewalk in Virginia USA an hour or two after rain. It was much more slender and elongate than the species in this picture, and wholly earthworm-colored below the "neck." However, the gestalt of the head was exactly like in this species. It moved pretty pokey, with a sinusoidal snaking action. I googled flat head worm and here I am. Blows me away to see something so novel on the street after walking around Virginia for 25 years.

On a side note, these things eat earthworms by extending their esophagus-analogue into their prey. Disgusting! Isopropyl 02:09, 10 May 2006 (UTC)

Girls v/s boys[edit]

In most of the exams Girls outperform boys. Why is this so?

There isn't a straight answer to this. It's most likely a combination of:
    • Genetic factors. For example, girls and boys may have different brain structures that lead to proficiencies at different tasks. This issue is deeply controversial, and while most people agree it exists, there is alot of heated argument over how significant this effect is. (and whether it is moral to act according to this)
    • Social factors. Society expects different things of boys and girls - and among boys, for example, there may exist a general anti-academic sentiment that means boys work less hard in their studies. In many western societies, for example, there is a general perception of young males as lazy, and this sort of thing feeds back into the system and decreases individual motivation. Expectations can drive reality.

Of course, many people believe in the opposite - that boys outperform girls academically. Go figure. See also Sex and intelligence --Fangz 14:00, 9 May 2006 (UTC)

I think which gender performs best in exams correlates with ages, subject studied & also with race and social conditions (though frequently race is considered a proxy for social conditions). Certainly in the UK there are a range of statistics collected on this. Some research links are here and some statistics are included in here. This one also looks useful. AllanHainey 14:23, 9 May 2006 (UTC)
And type of exam of course. Skittle 15:05, 9 May 2006 (UTC)
My theory is that girls are better at memorizing things and recalling them than boys are. This is because boys are more analytical, they will tend to try to figure out if a thing makes sense before committing it to memory.
That's your well-considered opinion? Black Carrot 23:38, 9 May 2006 (UTC)
At the lower levels, girls tend to generally outperform boys, at higher levels boys outperform girls. Boys are better at specialization, and girls are better at generalization in education and academics. My own thinking. -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 04:42, 10 May 2006 (UTC)
Sorry, not that I disagree with you, but would you mind setting evidence to that opinion? It may cause some general interest. Luthinya 12:02, 15 May 2006 (UTC)
I agree with Mr. Mac Davis. Does that count as evidence? :P --Russoc4 18:35, 16 September 2006 (UTC)

Magnetic flux[edit]

A 50 turn coil has a sinusodial magnetic flux. Maximum rate of change of flux is 5Wb/s. Find the peak amplitude and RMS voltage.

I know induced voltage is e = d\lambda/dt, and \lambda = N.A.B, but I'm not sure where to go from there..?

Bwgames 12:37, 9 May 2006 (UTC)

See Faraday's law of induction for an explanation of your first equation (but note that \lambda\not\equiv\Phi). Note that the flux is a physical quantity independent of what you happen to do with it, so it can't possibly account for N's effect. See RMS for information on how to calculate the last bit. --Tardis 18:06, 9 May 2006 (UTC)

Hair[edit]

How does body hair know when to stop growing, and when to grow back? 87.194.20.253 15:52, 9 May 2006 (UTC)

This was asked very recently here. If you are the one who asked the question, please keep in mind that you must return to the Reference Desk to see the answers. --Kainaw (talk) 16:57, 9 May 2006 (UTC)

grain drying[edit]

i need relevant information about grain drying

I would start with food storage and harvest. --Ginkgo100 19:00, 9 May 2006 (UTC)

Brushless alternator[edit]

what about the brushless alternator voltage regulation?.I am a electrical engineering student.Its a portion on our syllabus.my question is again repeating,can you give any idea about the voltage regulation of brushless alternator?.I am engineering student in india.

                                       Thank you

what about the brushless alternator voltage regulation?.I am a electrical engineering student.Its a portion on our syllabus.my question is again repeating,can you give any idea about the voltage regulation of brushless alternator?. —Preceding unsigned comment added by Chandykv (talkcontribs)

Aren't your lecturers meant to teach you the stuff thats on the sylabus?! Brushless presumablly means permanent magnet so you couldn't adjust the field strength. The only obvious approach would be to either use a tap changer or convert the voltage later with some kind of variable transformer or power electronics. Plugwash 18:27, 9 May 2006 (UTC)

Split up files[edit]

Because of a problem which is a long story, I need to send a large file to my home email address. The problem is my email services will not allow a file this size to be sent. This is an executable file so PKZIP will not shrink it much if at all. Is there a way to break the file up into parts and send each part seperately, then reconnect the parts on the receiving end?

You can break a file up into specified parts in WinRAR (and, I think, WinZIP). In WinRAR you'll have file.rar, file.r01, file.r02, and so on. You just put them all in one folder at the other end and open any of them and WinRAR does the rest. Sum0 20:29, 9 May 2006 (UTC)
Or, you can just split it and then add the pieces together by hand (careful about the metadata though).--Frenchman113 on wheels! 20:58, 9 May 2006 (UTC)
Google "file splitter" and you will find many freeware programs that would suit you. You do need a copy on your target machine to do the recombining. --Seejyb 21:02, 9 May 2006 (UTC)
PKZIP (or at least the old DOS versions) can split and rejoin files just fine. --Serie 21:22, 9 May 2006 (UTC)
I can recommend Chainsaw [27] It's freeware and you don't even need to install it on your target machine. Files can be up to 2GB. Slumgum | yap | stalk | 21:28, 9 May 2006 (UTC)
GMail accounts are free, allowing over 2GB of storage. Regarding compression of executables, I have just experimented with using WinZIP to compress to exe files and achieved over 50% on each, so I do not understand that portion of the question. --LarryMac 17:24, 10 May 2006 (UTC)
Unless the file is extremely sensitive (in which case, why are you sending it by e-mail?), you can try and send it through an online service such as Yousendit.com. I use them frequently for large files, and it works very well. — QuantumEleven 12:26, 11 May 2006 (UTC)

Notepad[edit]

When I press Ctrl + S in notepad while at the end of a line, the cursor jumps back several spaces - why?

When 'word wrap' is activated, and a long string such as "enteric/genital" wraps to the next line, and I decide to turn it into "enteric or genital", why does notepad ignore the fact that "enteric" will now fit on the line above? --Username132 (talk) 20:10, 9 May 2006 (UTC)

What OS is that? Ctrl+S is pretty much Windows standard Save As, my notepad does just that.
OS is WinXP. Notepad still saves, but at the same time I get the weird cursor jumping thing. --Username132 (talk) 20:51, 9 May 2006 (UTC)

As far as I know, both these things are bugs in notepad. They have been bugs since the earliest days of Windows 95. Why no one at Microsoft has bothered to fix it in 10 years is beyond me, but it's closed source so no one else can fix it. If it really bugs you you can use Wordpad (Which has its own host of bugs and problems, but has the above bugs fixed), or download another text editor. —Pengo 02:19, 10 May 2006 (UTC)

One workaround, if you're not operating with the window maximized, is just to change the width or height of the window by a pixel or two, which will cause it to recalculate the wrapping. —Zero Gravitas 02:29, 10 May 2006 (UTC)
If it really bothers you (I use Notepad a lot for offline e-mail writing, and this bug drives me nuts) there are several "Notepad replacement" programs out there which you might consider taking a look at, depending on what you want Notepad to do. Examples include Win32pad, BDV notepad, NotepadEx, Notepad2, and here's another list. Good luck! — QuantumEleven 07:56, 12 May 2006 (UTC)

Pigment in UV beads[edit]

What pigment(s) are used in ultraviolet-sensitive beads? The web sites I've checked don't indicate the identity of the color-changing material. Hyenaste [citation needed] 20:44, 9 May 2006 (UTC)

See photochromism --Seejyb 22:14, 9 May 2006 (UTC)
Ah, that's quite interesting. Thanks! Hyenaste [citation needed] 22:19, 9 May 2006 (UTC)

satelites[edit]

how accuratley are satelites tracked say if there in orbit around the moon or mars? and does the tracking relay on just radar based systems, or are other methods used? cheers Colsmeghead 21:06, 9 May 2006 (UTC)

I probably shouldn't answer because I really don't know, but I have a sneaking suspicion that using resources to actually track the paths of satellites is not a common practice. Their orbits are incredibly predictable (negligible friction and simple orbit patterns), and I don't see any reason why a simple mathematical extrapolation of the predicted orbit on a computer screen wouldn't suffice to pinpoint a satellite's current position.
In movies you often see the satellite paths swerving off course on computer screens and then blinking out as they break up in the atmosphere, but I doubt that would happen in real life as they're probably just simulations (of course... I don't really know that).
On the other hand, I imagine it's pretty easy to determine the position of the sattelite by triangulating it's signal, though would you really want to?  freshgavinΓΛĿЌ  06:33, 10 May 2006 (UTC)
I don't think it would be that easy at all to triangulate the position of a satellite that is in orbit around another planet. The two sensors that were picking up a signal from the satellite would have such a small angular difference that the measurements would have to be extremely precise. I don't actually know if I'm right or not, it just seems implausible. Dismas|(talk) 10:35, 10 May 2006 (UTC)
Yes, I imagine you're right. I was thinking too short-range.  freshgavinΓΛĿЌ  00:36, 11 May 2006 (UTC)

In general, a satellite's orbit can be determined by making a series of observations in some reference system: from a ground station on earth to the satellite, from the satellite to the ground station, or between satellites. A series of measurements of direction, range, or range-rate could be used to refine the orbital parameters.

A number of methods have been used to track earth-orbit satellites: photography to determine direction, electromagnetic signals such as lasers or radar–either impulse timing or phase comparison to measure range, and Doppler shift measurements to determine range-rate. Günter Seeber (2003). Satellite Geodesy (2nd Edition ed.). 

For satellites orbiting other celestial bodies the most convienent method is most likely the Doppler method. Another technique that should probably be metioned is interferometry to determine direction. Very Long Baseline Interferometry is used to realize the reference systems in which measurements are made, and our VLBI article mentions that it was used to track the Huygens probe accurately enough to measure windspeed on Titan. EricR 12:32, 10 May 2006 (UTC)

The actual orbit of a satellite is actually NOT easy to predict with great accuracy. In fact, the US military is actively tracking all artificial satellites orbiting the Earth, and frequently updating the characteristics of all orbits. This information is provided to Space Agencies and other operators, who may actually activate small rocket engines on the platforms to adjust or correct the orbit on a regular basis. These orbital corrections are necessary because the Earth (or any celestial body, for that matter) is neither homogeneous nor symmetrical (even the center of mass of the Earth is moving as a result of ocean currents and wind systems), and because the orbit of each satellite results from the gravitational attraction of many (as in infinitely large) objects (mostly the Sun and the main planets, as far as the Solar System is concerned). Friction is often small, but never totally negligible either, and then there are other forces, such as the solar wind, impact from cosmic dust, etc. While each perturbation, by itself, may have a rather small impact, the cumulative effect of all these mechanisms over a long period of time does result in the 'degradation' of the orbit, hence the need to periodically apply corrections. Hope this helps. --Michel M Verstraete 21:57, 12 May 2006 (UTC)

Well that's an answer I can trust. Teaches me to assume so much!  freshgavinΓΛĿЌ  02:11, 15 May 2006 (UTC)

May 10[edit]

Sensation of speed[edit]

Why does sensation of speed decrease with increased distance from the road/increased altitude? i.e. Why does 20mph in a go-kart feel so much faster than 20mph in a standard road car? I presume that it is the same reason why when you are on an aircraft coming into land it appears that you are going slower than any road traffic about until you are very close to the ground when you are suddenly aware of how fast you are truly going? Does this effect cause difficulties for pilots?

My initial vauge guess is that it is something to do with paralax, but I don't see how that would have any significant difference between being 20cm or a metre or 2 metres above the road? Thryduulf 00:53, 10 May 2006 (UTC)

If you are the passenger in a car, you can see why. Look out the window. Get a feel for how fast you are going. Then, look at the side of the road. Get a feel for how much faster you are going. Then, look down at the road right next to the car. See how much faster you are going. In a go-kart, you can easily see the road speeding by in your peripheral vision. In a car, you cannot see the road as easily because you are higher and the doors block much of your view. In an airplane, you can see even less of the ground below you. Also note that the body picks up on many other queues: wind, motor pitch/volume, acceleration force... --Kainaw (talk) 01:59, 10 May 2006 (UTC)
If you look straight down, the angular speed at which the ground passes through your field of vision is v / h, where v is your true velocity and h is your height above the ground. For other angles -- for example, if you're looking 20° below the horizon -- there's a slightly different formula that involves trigonometry, but it still scales like v / h. Well, clearly as h increases, this quantity decreases.
Rather than hinder pilots, it can actually help them land! Given that you're travelling at some roughly constant velocity, you can tell how high you are by watching features on the ground pass by. The faster they seem to be going, the lower you are. On the other hand, if there are no helpful features below, you can be in trouble; this is one reason why you don't want to try to land on glassy water. Just try Googling for (glassy water landing). Melchoir 02:06, 10 May 2006 (UTC)
The biggest difference I'm aware of between those things, other than what's already been mentioned, is the vibrations. Go-carts have almost no suspension, and planes don't even touch the ground most of the time. The more you feel every little change in the road, the faster it feels. Black Carrot 22:21, 10 May 2006 (UTC)

My dad owns a 40-foot steel sailboat. On days with very little wind, when we weren't in enough of a hurry to turn on the engine, he would put me in a lifejacket, tie a rope around my waist, and drop me off the stern. What felt like not moving at all while on deck was fast in the water. It just has to do with proximity to the reference point used to estimate your speed. moink 20:51, 12 May 2006 (UTC)

Shortest scientific name[edit]

I just came across the consonantless Ia io [28] (Great Evening Bat) and was wondering if this was the shortest binomial name there was, and if there was a place in wikipedia for such mindless trivia. —Pengo 02:31, 10 May 2006 (UTC)

Googling for 'shortest binomial name' seems to indicate that it is. As to Wikiappropriateness, why not? Once an article on the animal exists, there's no reason for it not to include that. —Zero Gravitas 04:49, 10 May 2006 (UTC)
Hey man, I'd say that's actually rather informative trivia. I'm sick of hearing DYKs like "Did you know that Jasper Weevuns' cat died in 1989?" that seem to serve no purpose other than to introduce the article.  freshgavinΓΛĿЌ  06:40, 10 May 2006 (UTC)
It is the shortest binomial name recognized by the ICZN, and the Great Evening Bat now has an article. –Mysid(t) 08:20, 10 May 2006 (UTC)
Jasper Weevuns' cat died? - Nunh-huh 04:45, 11 May 2006 (UTC)

Nice work creating the article. Thanks Mysid, and everyone who researched it! —Pengo 13:10, 11 May 2006 (UTC)

As for mindless trivia, I've nominated it for the "Did You Know" section. Let's see. –Mysid(t) 19:25, 11 May 2006 (UTC)

Sense of Navigation[edit]

I know there are five main senses, but for the other senses that are not the five main senses would sense of navigation be considered a sense in some form or fashion?

That's a different use of the word sense. The "five senses" (actually more like six or seven if you include things like proprioception and kinesthesia) are the methods by which we receive information from the outside world. The "sense of navigation" is more like "common sense" or the "sense of proportion" in that it occurs completely within the mind, and in fact depends on the other senses. If you couldn't see, hear, touch, smell, taste, or feel where your limbs are, you would have no idea where you were or which way you were going, and your "sense of navigation" would be useless.
On the other hand, birds and some other animals navigate by magnetoception. Maybe that's what you're talking about? —Keenan Pepper 04:22, 10 May 2006 (UTC)
See senses for a list of all the senses. Also, hammerhead sharks navigate by magnetoception. -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 04:25, 10 May 2006 (UTC)
Neat! Got a source so we can add it to the article? —Keenan Pepper 04:43, 10 May 2006 (UTC)
[29], [30], [31], [32] for hammerheads. For trout [33]. Somebody else can add it to the articles: Hammerhead shark, trout, magnetoception, senses. Also, as a note, the hammerhead's magnetoception is different from its electroception. I think most sharks use electroception from their ampullae of Lorenzini. -- Flag of the United States.svg Mac Davis] ⌇☢ ญƛ. 07:24, 10 May 2006 (UTC)
You may be thinking of the act of navigating a geographical area using a sort of mental map. This is a cognitive ability, not a perceptual one (at least in humans). See cognitive map, although that article covers more abstract maps than strictly geographical ones. --Ginkgo100 19:41, 10 May 2006 (UTC)

Why an untied balloon flys foward[edit]

Hi. When a balloon, filled with regular air. Is inflated to a large size, not tied, and then released, it goes flying. This is common sense, however, I need to know the physics of it. What is the physical explanation for why it flys? I really need this question answered soon. Thanks Tobyk777 04:23, 10 May 2006 (UTC)

You mean, Hot-air balloon#Construction and theory of operation? Or a toy balloon the size of my head? Melchoir 04:35, 10 May 2006 (UTC)
I mean a toy balloon the size of your head. Basicaly, when you blow it up (with your mouth), then let go before you can tie it. Thanks Tobyk777 04:36, 10 May 2006 (UTC)
Hmm... maybe because breath is warm? Melchoir 04:38, 10 May 2006 (UTC)
Oh, before you can tie it! I missed that part... Melchoir 04:39, 10 May 2006 (UTC)
What exactly is your size in hats? I was guessing around 7 7/8[34] but am now revising that downward a bit. EricR 12:50, 10 May 2006 (UTC)
Okay, there's a short description at, woulldn't you know it, Balloon rocket. That article links to thrust, which is also good. Ultimately it's Newton's third law; the air being shot out the back of the balloon is balanced by a forward force on the balloon itself. Melchoir 04:42, 10 May 2006 (UTC)
It's Newton's third law in action! —Keenan Pepper 04:42, 10 May 2006 (UTC)
Thnaks the recomended pages told me everything I needed to know. Tobyk777 05:03, 10 May 2006 (UTC)

Hyacinth Macaw - taking for a walk?[edit]

As it's summer here, I thought it would be quite nice to take my Hyacinth Macaw out for a walk with me in the sun sometime (or even just in the garden). He's fully flighted, so what would be the best way to keep him with me? A chain from his leg to my wrist, or one of those parrot harnesses you can buy on the internet? Anyone have any expierience with this? Thanks. --81.77.242.228 06:01, 10 May 2006 (UTC)

Personally I think it would be much better to return the bird to the wild where it could fly free. Alternatively you could give it to a bird sanctuary. Don't you think it is cruel and uneccessary to capture a free spirit like a bird ? That is my opinion.Antipodeite 11:31, 10 May 2006 (UTC)

Sunlight is good for parrots; kudos for trying to expose him to it. Animal rights activists' opinions aside, I would research the options. Above all, you want to choose a device that won't injure your bird if he startles and tries to take off. My birds' vet once mentioned she has seen injuries from bird harnesses, but that was several years ago and the design may have improved. I have also seen devices consisting of a leather loop on one end, a chain, and a quick link or snap link at the other end. The loop is for the human to hold, and the link is attached to the bird's leg band (this obviously wouldn't work for a bird without a leg band).
Oh, and in case there was any doubt, a bird sanctuary won't provide any better of a home than a dedicated parrot owner can provide. Releasing the bird to the wild would be cruel because a tamed and handfed parrot is very unlikely to survive. And unless the bird were released in its native habitat, if it does survive it can have severe repercussions on the local ecology. --Ginkgo100 17:08, 10 May 2006 (UTC)
There are lots of wild parrots in Southern California, I can't imagine they're native, but probably escaped or released, and they all look skinny, starved, and covered with mange. User:Zoe|(talk) 20:44, 10 May 2006 (UTC)
There are also The Wild Parrots of Telegraph Hill], San Francisco. --LarryMac 20:53, 10 May 2006 (UTC)

Mozilla Firefox Text-zooming[edit]

(Taken from Talk:Mozilla Firefox)

I use Firefox to browse Wikipedia and other websites. I often use the Control +/- function to make the text larger or smaller. For some websites this works really well because the lines of text stay the same width. For other sites though, the lines of text get wider and wider so that I have to scroll back and forth horizontally just to read them. On some sites, like Wikipedia, when I make the text larger it makes the lines get narrower and narrower.

So is there anything you can do with your Firefox settings or extensions to fix this problem, or is it just up to the webpage designers (including those who maintain the MediaWiki software) to code their pages better to fix this problem?

Any help with this would be much appreciated. I've got a small monitor, and I often need to make the text bigger so that myself and others can read it without being real close to the screen. Thanks!

You can change your Wikipedia skin so that nothing extra is on the left of the screen. With the default Monobook skin, the navigation, search, and toolbox links on the left need to grow when you zoom in. This will leave less space for the article. If you move those links somewhere else, then you'll get more screen space. --KJ 10:54, 10 May 2006 (UTC)

science[edit]

think of examples in your everyday life where the princlples of reaction rates are applied( temperature, disloving, or space) ~~

  • Do your own homework. If you need help with a specific part or concept of your homework, feel free to ask, but please do not post entire homework questions and expect us to give you the answers. Melchoir 08:18, 10 May 2006 (UTC)
Disloving may occur in an unhealthy relationship, for example. ––Mysid(t) 08:28, 10 May 2006 (UTC)
Yes, often including heated arguments, cold shoulders, and a need for more space. And overreactions. Melchoir 08:31, 10 May 2006 (UTC)
In many relationships there is a reverse coleration between space and heated arguments. -- Chris Q 08:51, 10 May 2006 (UTC)
I believe you mean "negative correlation". Black Carrot 22:09, 10 May 2006 (UTC)

The more objectionable a person's statements, the more quickly you react by disloving them. Grutness...wha? 06:55, 11 May 2006 (UTC)

Stars[edit]

I read the stars article, and there were a few things i didnt understand. Firstly, what the 'fuel' in the stars is. Secondly, when they die (im pretty sure this is when they run out of fuel). And thirdly, what size they need to form into black holes. Thanks. ````

If Star wasn't enough, you might want to try Stellar evolution and Black hole. Melchoir 10:31, 10 May 2006 (UTC)
Fuel of the star changes over time, mostly it is the fusion of hydrogen. --Mac Davis 11:11, 10 May 2006 (UTC)
By mostly, he means almost the entire life of the star, it changes to helium in the chain of events which leads to the collapse when it dies, then as it collapses anything gos. So i'd say about 99.99% of its life it is hydrogen. Philc TECI 18:20, 10 May 2006 (UTC)

Thyristor triggering[edit]

A gating current can latch a thyristor.But is it possible to latch a thyristor during the(90 -180)degree fall of input sinusoidal voltage? We know that a thyristor can be triggered by the +ve half rise(0deg to 90deg) of sinusoidal voltage,but a little gating current would latch it at a smaller potential than it would have.So is this triggering possible during the +ve half decrease(90deg - 180deg)?

Airplane[edit]

How were the planes that delivered the first atom bomb protected from electromagnetic pulse? Is it possible to protect ordinary devices from EMP weapons as well?

The Enola Gay and Bockscar had no EMP protection because EMP was discovered in 1962. The planes' electronics (what little there was, this was the era of cables and pulleys, not fly by wire and HUDs) used vacuum tubes, which are more resistant to EMP than today's fancy-smancy millivolt-spike-will-make-the-smoke-come-out transistors and microchips. Electromagnetic bomb suggests using a Faraday cage for protection. You won't be laughing at my tin foil hat when the EMP bombs start to fall, I tell you! Weregerbil 13:27, 10 May 2006 (UTC)
This was also a major plot element in Harry Turtledove's Worldwar series.
Whoops, that was me. --Ginkgo100 19:34, 10 May 2006 (UTC)
If you read the Electromagnetic pulse article, it addresses this directly:
It is important to note that many nuclear detonations have taken place using bombs dropped by aircraft. The aircraft that delivered the atomic weapons at Hiroshima and Nagasaki did not fall out of the sky due to damage to their electrical or electronic systems. This is simply because electrons (ejected from the air by gamma rays) are stopped quickly in normal (dense) air for bursts below 10 km, so they don't get a chance to be significantly deflected by the earth's magnetism (the deflection causes the powerful EMP seen in high altitude bursts), but it does point out the limited use of smaller burst altitudes for widespread EMP. If the B-29 planes had been within the intense nuclear radiation zone when the bombs exploded over Hiroshima and Nagasaki, then they would have suffered effects from the charge separation (radial) EMP. But this only occurs within the severe blast radius for detonations below about 10 km altitude.
--Fastfission 17:37, 10 May 2006 (UTC)

Melting Point[edit]

I wish know the melting point of Empirical formula : C8H12O5

Chemical Name: 1,4:3,6-dianhydro-2-acetyl-D-glicitol

or

2-acetyl isosorbide

Regards N Thanks

SciFinder says that it is reported as 78 °C in this patent: WO2003027119 A1 2003 --Ed (Edgar181) 14:35, 10 May 2006 (UTC)

Calcium Hypochlorite[edit]

Having found several tins, what is it used for. I am familiar with Sodium Hypochlorite which I use for sterilising beer bottles.

Sodium hypochlorite is commonly known as bleach. It's not unique to beer bottles. As for calcium hypochlorite Ca(ClO)2, its chemically very similar to NaClO, though, essentially has more chlorine, which is the active component of bleach. You can find more detailed information in the articles. --Chris 16:11, 10 May 2006 (UTC)

Colors --- this might proof im insane...[edit]

I was just wondering, when a baby named X belongs to a family named A, and a baby named Y belongs to a family named B, grow up at the same time. Lets say X sees a banana green, but his family A says a banana is yellow, and he sees a tomatoe blue and his family says the tomatoe is red! When he sees the sea red his family says the sea is blue! While the other baby sees a red banana and his family says its yellow and he sees a green tomatoe and his family says its red and he sees a yellow sea and his family says its blue... anyways the point is both babies will grow up, knowing all the colors, and knowing all their names but, they will be seeing somethin different! He sees a red banana but he calls it a yellow banana! he sees a red car and calls it a yellow car, and the other one will see the car blue but call it yellow too. I just want to know if anyone can proof that everyone sees the same colors...? it could have a simple answer i just want to know.

What you are talking about has nothing to do with colors; it has to do with the fact that language is semi-arbitrary. This is true but within limits. For example, someone who has been taught that the color of a banana is "red" will soon run up against the fact that in English the color of a banana is called "yellow", and everywhere they go people will identify it as such. So yes, they could learn arbitrary color names, but once they get out into the world in any capacity (even kindergarten) they will have it disciplined out of them pretty quick. There is some flexibility in this, of course, but language is generally not about one individual knowing words and correspondences, but communication between individuals with reliance on a common vocabulary. Meanings change, words get added, etc., and I don't know the dynamics of how that happens, but one individual who has been taught "incorrect" definitions is unlikely to have much effect by themselves. The colors of the banana, car, etc. themselves have to do with the wavelength of the light reflected off of them. There is some fairly compelling evidence that most human visual hardware perceives these wavelengths more or less the same way (focal colors correspond with the same wavelengths of light, cross-culturally), though how that translates into intuitive consciousness is a hard-to-define question and a rather nebulous research area, as I understand it. --Fastfission 17:34, 10 May 2006 (UTC)
This actually HAS something to do with colours, and I have thought about THE EXACT SAME THING!!! Quite simply, no one can "see" the same colours. Only you know what goes on in your head, and what you see. If I see purple what you see yellow*, that has only do to with chemical thingies. According to the laws of physics, however, there is a very steady, rule-following shift in visible light from the roundabout 400nm to 700nm wavelength (red to purple), so your brain shouldn't actually be complicated enough to be able to truly mix these up. If it was a question of chemistry alone, I would think that every person sees everything bit different, in fact some humans may see, say... light at 390nm, while others have lower limits at 410! Now, THAT is chemistry, and THAT is the only thing which may vary here. The true shift in colour is something limited by physics, so that you CAN'T misplace purple where once was green. At least I can't see how on earth that could be done. No, can't be done, I'm rather sure of it. :) * Of course this was hypothetical. It is very important to remember that "yellow light" in this case is not something which may vary, but is defined at a certain wavelength, as with all colours. 213.161.189.107 19:31, 10 May 2006 (UTC) Henning
I see this as a combination of the above two, plus some confusion with the original question. What you really seem to be asking is "what if X sees a banana as what outside observer O calls 'yellow' but Y sees a banana as what O calls 'red'?".
This situation can potentially happen, but it can't be observed. When asked, X Y and O all agree that bananas are "yellow", and will point to the same "yellow" on a color wheel, regardless of the precise way in which their brains individually process the notion of "yellow". — Lomn Talk 19:43, 10 May 2006 (UTC)
See Epistemology, Semantics, Semiotics. --BluePlatypus 19:45, 10 May 2006 (UTC)
Although the article has a somewhat strange style IMO, see also qualia. Ardric47 20:53, 10 May 2006 (UTC)
See also color blindness and tetrachromat for additional, unusual ways that people may perceive colors. TenOfAllTrades(talk) 20:19, 10 May 2006 (UTC)

Balance[edit]

I know humans have balance, but do animals with four legs have balance too?

A four-legged animal would fall over without balance - just not as easily as a two-legged animal. There are all kinds of activities that might shift the animal's center of gravity such that it would fall over if it couldn't sense the imbalance and correct it. --Ed (Edgar181) 20:20, 10 May 2006 (UTC)
Isn't the primary function of a tail a balancing aid? --Kainaw (talk) 20:21, 10 May 2006 (UTC)
All vertebrates (sea, air and land) have organs for equilibrium, used to balance. I wonder if ants know when they are upside down?
See collective nouns --Seejyb 21:41, 10 May 2006 (UTC)

Gender names[edit]

Hi: I notice that in english language male and fmales of diferent species have special names and also when they refer to a group and population have also different names e.g. hen - ruster bore - school - herd etc. How I can find a table or place that list all af those names without going species by species? Thaks MhE

Try List of gender names -- SGBailey 23:02, 10 May 2006 (UTC)
Our article on Collective nouns links to many lists you may find helpful. I'd treat that with caution, however, some of the lists are BJAODN in my view. --Howard Train 04:56, 11 May 2006 (UTC)

Xenotransplantation Affects Germ-line?[edit]

The article on xenotransplantation says "Disease transmission (xenozoonosis), and possible long-term effects of xenotransplantation on the human gene pool and permanent alteration to the genetic code of animals are a cause for concern." - how does it affect the gene pool? Unless it's testicle transplant, I don't see how the germ-line is affected? --Username132 (talk) 21:34, 10 May 2006 (UTC)

The germ line isn't affected. I've corrected the article. TenOfAllTrades(talk) 21:49, 10 May 2006 (UTC)

A past exam question was "Xenotransplantation will never solve the issue of the kidney tranplant waiting list. Discuss" - I'm wondering how this could be so? Is it because the engineered HLAs wouldn't please everybody all of the time... I mean what's the point in xenotransplantation if you still have to worry about finding a match? --Username132 (talk) 21:56, 10 May 2006 (UTC)

Numbered lists in Word[edit]

Anyone know how to make numbered lists in word where the numbers are genuine numbers and not a "magic field" using Word 2003 in XP?

I maintain a list of events and each month add any new ones at the bottom. I then want to be able to sort on (say) field 3 and have the numbers stay with the relevant line, so that i can later sort by field 1 and put them back in order. When I was using good old Word2, numbered lists just inserted text. Now it seems to do this magic stuff - including ignoring any numbers already there! Frustrated. -- SGBailey 21:40, 10 May 2006 (UTC)

Have you considered using Excel instead? It'll let you sort things however you want without mixing up the lines. --65.57.245.11 23:01, 10 May 2006 (UTC)
Yes, and I probably will convert. However I have only just upgraded from Word 2 to Word 2003 and the behaviour is very different so I'd like to know how to achieve to old behaviour. -- SGBailey 07:56, 11 May 2006 (UTC)
I'm no Word expert (Microsoft Word, that is; I like to think I'm coherent), but when it starts trying to do its magical formatting against my wishes, I hit CTRL+Z and hope for the best. --Ginkgo100 16:49, 11 May 2006 (UTC)
Tools > AutoCorrect > AutoFormat As You Type > Automatic numbered lists. -- Filliam H Muffman 22:33, 12 May 2006 (UTC)
That lets you manually enter lists - this is what I have to do now. What I was looking for was a way of using the "Format | Bullets and Numbering | Numbered Lists" magic to auto number a selection and then to "go away" and stop being "magic" - that is convert the resulting list into "text". If it was excel, I'd do a "copy" "paste special | Values" for a similar effect. The "magic" makes the numbers and tabs not part of the text that you have to work hard to get into and over which you have no control. Thanks though. -- SGBailey 21:57, 13 May 2006 (UTC)

Thioglycolic acid[edit]

After enduring an increasingly dreadful smell in the laboratory in which I teach for five days or so, I found that thioglycolates had been poured down a sink into an open trap below, rather like a sink in a cupboard, where they had presumably released thioglycolic acid into the laboratory all that time. I assume that the water in the trap must have been somewhat acidic. Does anybody have any similar experiences, and should I be concerned for my health?G N Frykman 22:07, 10 May 2006 (UTC)

  • This PDF file should help you along. If there's no respitory problems are rashes, you're probably fine, but it can't hurt to have yourself checked by a doctor anyway. - Mgm|(talk) 12:07, 11 May 2006 (UTC)
If it's still a problem, bleach will oxidize the thioglycolic acid to a non-volatile compound - this will reduce your exposure to breathing its fumes and will kill the smell too. --Ed (Edgar181) 12:25, 11 May 2006 (UTC)
Thanks for the helpful replies. I've now found that the experiment was being conducted with methyl thioglycolate, and what went into the trap was a filtrate. We poured litres of NaOH solution into the trap, and that seemed to get rid of the smell. I have not noticed any harmful effects, but this has become an H & S issue.G N Frykman 16:56, 11 May 2006 (UTC)

Pulse & Blood Pressure[edit]

In all the sources I've been able to find (a doctor via my sister's memory, Wikipedia, WebMD, some site off Google) except one (my dad), the ideal resting adult pulse is in the 60-100bpm range. Now, is this the "within this you're healthy" range, or the "outside this you're seriously messed up" range? Let's say I have a resting pulse of around 96 at 18 years of age. What's that mean? (BTW, to anyone who plans to say "ask a doctor", I'm already scheduled to get a physical in a few weeks, and all I'm asking is what the webdoctors' advice means. Eat me.) Black Carrot 22:17, 10 May 2006 (UTC)

Not a doctor, but being outside that range definitely sounds to me like you'd be pretty "messed up", or at the very least, "unhumanly". Athletes taking drugs to thicken their blood can often slow their heartbeat to less than 50bpm, but it's extremely irregular and can cause serious health problems if it isn't normalized for long periods of time. Having a fast heartbeat could be problematic depending on your body size/mass, but I'm willing to bet your heart beats so fast because you have a fast metabolism. My heart beats pretty fast too, although I haven't calculated in a while.
On the other hand, if you don't have a fast metabolism, and you are rather largely built, there could be a problem, and I'd advise you to go to a real (rather than a web-) doctor : ).  freshgavinΓΛĿЌ  00:13, 11 May 2006 (UTC)
It's just an "outside this you're abnormal" range, If the heartrate is < 60, you have bradycardia, by definition. If it's higher than 100, you have tachycardia. You are in the normal range. There wwould be benign explanations, and serious explanations, if you fell outside this range, and you would need to see a doctor to determine which. The further you are outside this range the more likely that pathology, rather than normal variation, is the reason. Usually any significant arrhythmia produces symptoms rather than merely being noted when the pulse is taken. A resting pulse of 98 doesn't sound "seriously messed up", but your doctors visit should clarify that- Nunh-huh 00:27, 11 May 2006 (UTC)
Interesting. So, it's more towards the "within this you're fine range"? 'Cause I'm just on the edge of it. Also, you seem to be saying that certain other factors (metabolism, build) would shrink the range to something more specific. Do you know where I can find a table that lists that? Black Carrot 02:02, 11 May 2006 (UTC)
Incidentally, I'm fairly skinny (even though I don't excercize or diet), so I figure I've got a fairly high metabolism. Black Carrot 02:04, 11 May 2006 (UTC)
Yes, it's basically a "within this you're fine" range. There's no other well-established range based on other factors, but being in good athletic condition tends to lower the heart rate. - Nunh-huh 02:25, 11 May 2006 (UTC)
There's also a physical fitness component. The better your aerobic fitness, the slower your resting pulse. A high resting pulse could indicate a need for more aerobic exercise. --Ginkgo100 20:46, 11 May 2006 (UTC)

Color[edit]

I was thinking about this before and it just occured to me that I can ask the all knowing wikipedians if they have a usefull answer for me. What I was thinking of is the possibility that there are other colors in the world that humans aren't able to see and therefore because we don't live with those colors in our lives, they are also unimaginable colors.

I was thinking of this because I recently remembered that dogs can only see in shades of red, so maybe humans can only see in shades of blue red and yellow and mixtures of them. I talked to my dad about it, who isn't at all an expert, but he said that there are shades of those three base colors that we can't see, but what I'm talking about is major colors, not just shades. Anyhow I came to wikipedia trying to find an answer and got myself on the Pentachromat page. Now, you might say that my question is answered on that page, but I don't understand all that science blah blah blah.

So if anyone can give me an answer, that would be cool. Thanks a lot RENTAFraiseFruitPhoto.jpgFOR LET? röck 00:01, 11 May 2006 (UTC)

Basically yes, there are animals that can see colors that we can't imagine. By "imagine" I mean we can't imagine what the color would look like, because, obviously, we can't see it, but we know pretty much exactly what color it is. Ultraviolet (the color after purple) can be seen by some animals, such as butterflies, and though the name would suggest it looks like purple, it doesn't, because if it did look like purple, it would be purple, and then we'd be able to see it. There is no way to imagine or describe how ultraviolet would actually look, it's inconceivable.
Some animals can apparently also sense infrared (the color before red) light, but I don't think they can actually see it, and instead feel it like heat or smell. They most certainly don't experience like the military does with their infrared sensors—as a colorful spectrum of all of the visible colors of the rainbow.  freshgavinΓΛĿЌ  00:30, 11 May 2006 (UTC)
Are you sure they can't 'see' it in detail the way we can? BTW, you don't feel smell, you smell it (via chemical sensors), and infrared is an electromagnetic wave just like visible light, so I don't imagine the sensors could be much different. Infrared unfortunately doesn't say, and neither does a quick Google search. Other than that, ditto. Black Carrot 01:58, 11 May 2006 (UTC)
I meant to imply "feel it like heat" or "smell". I'm merely repeating what I've read in the past about infrared sensors, which seems to imply that the only animals that use it can't actually see it the way you would imagine they do.  freshgavinΓΛĿЌ  04:30, 11 May 2006 (UTC)
Some people can see ultraviolet (see Aphakia). Ardric47 03:51, 11 May 2006 (UTC)

The short answer is yes; even limiting to the range of "visible light" (excluding ultraviolet, infrared, and so on), there are infinite colors we cannot see or imagine. Technically, though, since colors exist only in our heads, by definition I suppose there cannot be a color that no one can perceive. Color is complicated. An objective description of a color would need the intensity of each frequency, along the entire spectrum; that is, you could draw a curve of intensity vs. frequency (wavelength). Since (most) human eyes have three cones, we see in three color "dimensions". For each type of cone you can draw a curve showing how much it responds to different frequency light. (For instance, see the figure at the bottom of [35].) Therefore, we are trichromats. Dogs appear to be dichromats, as are humans who are "color blind". Every frequency of light stimulates the cones to different degrees; a mixture of frequencies as is normally present stimulates all three cones but to different amounts. Ultimately, the signal from the eye only carries three pieces of information: the red, blue, and green "channels". For a dichromat, two different colors (patterns of light intensity at different frequencies) may stimulate his 2 cones the same way, but would stimulate our third cone to different degrees, and so we could tell the two colors apart. Our televisions and computer screens only need three colors to produce the "full spectrum" of colors, but don't think that there is anything special about three. If someone (or an animal, or an alien), had a fourth cone with its own sensitivity pattern (say to yellow), two colors which look the same to us might look completely different. For instance, on my computer, purple is created with a mixture of red and blue; to a tetrachromat (or even a trichromat with different cone sensitivity patterns), the red/blue mixture might look different than a pure purple. There are three primary colors because we have three types of cones, not the other way around. Color is subjective; there is no guarantee that two different trichromats will see colors the same way. Colors exist inside our heads. It's tough to grasp some of these concepts—I still struggle with some of them—so feel free to ask me to clarify. Interestingly, for some further food for thought: there is evidence that some human females are weak tetrachromats since they have two X chromosomes and therefore two copies of the red cone gene (although they wouldn't be full tetrachromats for reasons I can explain if you're interested); so two colors which look the same to a trichromat like me might look different to a woman with such an ability. Finally, there's a fascinating article at [36] discussing the evolution of color vision in primates. The red cone is the most recent, and appears to have evolved probably to aid in selecting fruit against a background of foliage, or perhaps to select different types of leaves. I apologize for the long post; please ask me if I haven't been clear. — Knowledge Seeker 04:46, 11 May 2006 (UTC)

Can I have a question on this? Even though there are three kinds of cones in a human eye, there's yet another kind of photosensitive cell, the rod, with a different spectrum of sensitivity. Wouldn't this mean that it makes us "tetrachromats" to some amount? The writeup I've quoted below says that "Rods are sensitive to much lower intensities than cones, so they are essentially used in night vision: in day vision, their input is not used at all since it saturates, so the cones take over.", and wikipedia seconds this, but still, can't it give us some extra colors at dusk? (Is that why viewing sunset over a lake is so beautiful? Probably no, that's more due to the way it lights the sky and some rays are blocked by clouds.) – b_jonas 21:26, 11 May 2006 (UTC)
(Wow, we even have an article on Trichromatic color vision! – b_jonas 21:35, 11 May 2006 (UTC))
The rods provide a grayscale image (no color). If the cones fire enough to register a color, the brain simply ignores the rods. I programmer I used to know only had rods - no cones. He couldn't see a thing outside in the daytime, but could make out shadows if it wasn't too bright. He wasn't able to see any extra colors. In normal eyes, if the brain didn't ignore the rods when the cones fired, you'd just get brighter/darker shades of the colors you are seeing. --Kainaw (talk) 21:36, 11 May 2006 (UTC)
I'm affraid that doesn't make much sense to me. One type of cone by itself would provide grayscale vision with no colors as well. This doesn't expalain how rods are different. – b_jonas 12:59, 12 May 2006 (UTC)
Read this excellent article about Colors and Colorimetry. – b_jonas 21:12, 11 May 2006 (UTC)
Examples: many birds and insects (including pigeons and honeybees) can see ultraviolet light. Thomas Eisner and colleagues Cornell University built a UV video camera and walked around in places like Panama. They discovered that many flowers have striking patterns visible in UV which apparently help attract the attention of polinating insects. ---CH 10:44, 16 May 2006 (UTC)

May 11[edit]

Man vs. Bear[edit]

Who do you think would win in a no-holds-barred, to the death fight between a man highly-trained in martial arts, in top physical condition and a grizzly bear of approximately the same size - assuming that there were no outside variables whatsoever (just the man, the bear and a piece of perfectly flat ground)?

(I've just been thinking about an advert from a few years ago in the UK where a guy was fighting with a bear, Street Fighter II-style over a fish.) --Kurt Shaped Box 00:31, 11 May 2006 (UTC)

Two words: human sushi. - Nunh-huh 00:33, 11 May 2006 (UTC)
The human would know he was going to fight, plan and train specifically for the fight, and go into the fight ready to kill. The bear would just chilling like a bear until he realized he was in a life or death situation. Chances are, the bear would realize it too late. --Kainaw (talk) 01:04, 11 May 2006 (UTC)
I would say the human would lose. The bear, after all, has claws and the human only has hands. One good swipe from the bear would end it. --Think Fast 03:06, 11 May 2006 (UTC)
Maybe the bear is highly trained in martial arts too? If not then I would think the human's best strategy would be to use his highly trained body to run away - terribly fast.
On a more serious note, any martial art that relies on blocking blows from your opponent is going to be pretty much useless against a foe capable of ripping your arm off. DJ Clayworth 03:46, 11 May 2006 (UTC)

DJ Clayworth 03:45, 11 May 2006 (UTC)

Need not be. A highly trained martial artist can evade blows and attack when necessary and when opportunity is available. He can execute blows to sensitive parts of the opponent to inflict maximum damage. This is something like a kid who is a martial arts expert who can bring a bulky man down. This is a possibility. Hence I say that man v/s bear contest would be a 50% chance for each -- Wikicheng 06:20, 11 May 2006 (UTC)
I doubt even a highly trained martial artist would be able to "evade" a smashing blow from an animal the size of a small car, charging at the speed of a small car, with a reach of almost a meter on each side. And I'm assuming flat land here; our ninja isn't allowed to climb any trees, and it would be unfair to force the bear to run downhill.  freshgavinΓΛĿЌ  06:35, 11 May 2006 (UTC)
You missed one small point in the question... the bear and the man are approximately the same size. So, this would be a baby bear, not a large one. --Kainaw (talk) 12:27, 11 May 2006 (UTC)
Yes, apparently I did. Well that just totally ruins it. A grizzly bear is a huge, formidable opponent. A young grizzly (without half the boldness of an adult) would be relatively harmless!  freshgavinΓΛĿЌ  00:16, 12 May 2006 (UTC)

The bear would probably win, unless the human got extremely lucky (and was able to score a killing blow to the bear's skull or throat without first being mauled). A human - even one in top physical condition with extensive unarmed combat training - would have almost no defense against a bear's claws and teeth without the aid of some kind of weapon. Raul654 06:42, 11 May 2006 (UTC)

How old and strong would a 65-70kg grizzly be? --Seejyb 10:04, 11 May 2006 (UTC)
Hmmm, bear of man-size. I am no zoologist, but I estimate that a one-year-old grizzly would be about the size of a man. However, still stronger than a man, as well as faster (running speeds of about 50km/h), and with those pesky claws and teeth where one hit will slice you open. My money is still on the bear. — QuantumEleven 12:44, 11 May 2006 (UTC)
My guess is the bear would run off unless there was a reason to stay. Grizzlies are pretty tough, but most animals will not fight unless there is a reason. A female with cubs would be pretty aggressive, or a male fighting over mating rights. A hungry bear can be hard to manage also, but without that bears would tend to avoid people.
The martial artist might be able to sweep the bear off its feet; on the other hand, bear pressure points are likely a lot different from human. --Ginkgo100 20:51, 11 May 2006 (UTC)
I think the outcome of the fight would mostly depend on whether the bear is coward or used to fighting a lot. I've read up on bears in Brehm some time ago and it said that individual bears vary a lot: some live a completely herbivore life, and hide from humans if they meet; but some cannot find enough food where they live that way, so they take up hunting, and some even enjoy it so much that they even go near human towns and eventually get shot there. However, I don't really know how much of this applies to a grizzley. – b_jonas 21:11, 11 May 2006 (UTC)

I think if the human was smart he wouldn't take the bear on face-to-face. To do some kind of "honorable" martial arts style fight with a bear wouldn't be very smart, as the two most dangerous weapons the bear has (claws/arms and teeth) are situated in the front of the bear's body. I'd think the best strategy would be to keep the bear slightly disoriented by trying to run around a fair amount, and probably attacking it from behind, trying to make some kind of fatal blow to the head or neck. Those are my first impressions of the situation, at least. EWS23 | (Leave me a message!) 00:52, 12 May 2006 (UTC)

molecules[edit]

Hi, I need help with my prjoect. I need help on molecules and elements. What is the different stuff about them. There meaning/deffinition. What are they made up of.

I'd start with reading our articles on chemical element and molecule. Feel free to bring any questions back here. TenOfAllTrades(talk) 02:57, 11 May 2006 (UTC)
Though possibly too simple for your project, if you want a more basic, easy-to-understand definition, check out the simple.wiki pages on chemical element, atom, and molecule.  freshgavinΓΛĿЌ  06:40, 11 May 2006 (UTC)

Gravitational time lens[edit]

As far as I know it's a silly, improbable theory that few people would put any proper thought into, but just for the sake of science...

Ignoring concerns with available technology (a big thing to ignore, I know) what problems might there be in using a massive object's gravitational field (for example, a supermassive black hole) to view the earth's light as it is bent around the supermassive object and back to the earth? I imagine half the problem would be finding such a source that would so accurately curve light so that the earth would be conveniently right within view, and the other half of the problem would be magnifying, filtering, and distorting the light to get an accurate picture out of it.

I know I'm talking about rediculously high resolution here (even within the earth's orbit, you're lucky to get a resolution less than a meter taking pictures of the surface), but since I'm assuming a time where problems with optical lenses have been done away with by much more complex technology is there any other reason why it wouldn't be possible to see the surface of the earth, light years ago? (Depending on the distance from the supermassive object.)  freshgavinΓΛĿЌ  07:05, 11 May 2006 (UTC)

I am not an expert in this field, but my guess would be that, yes, in theory it would be possible. I know you said that technology does not play a role, but remember that you would be observing the equivalent of the Earth from twice the distance to the black hole, which would probably be on the order of several tens of thousands of light-years. Even given obscenely advanced technology, there are limits imposed by physics as to up to what degree of arc you can resolve objects (given by the wavelength of light), so your telescope for these trans-temporaral observations would need to be massive, possibly with the diameter of the Earth's orbit (rough estimate), no amount of technology is going to defeat that requirement. Not to mention that the Earth's image will be greatly swamped by the light of the nearby Sun. Also, light does very strange things in the presence of strong gravitational fields - I could imagine the image would get rather distorted, but I'm not enough of an expert to pronounce judgement on this.
However, if you can beat these obstacles, yes, I think that in theory it ought to be possible. — QuantumEleven 12:36, 11 May 2006 (UTC)
If you're writing a science fiction novel, you could always construct an array of telescopes to give you the necessary resolution. The Very Large Array demonstrates the principle using radio telescopes. By spacing out the telescopes they can simulate the resolution of a 36 km diameter instrument without having to build a 36 km wide dish. Similar principles are being implemented in some new and proposed optical telescopes. The technique is a lot more difficult since the wavelengths of visible light are much smaller, but it's the same concept. If you put a constellation of space telescopes into solar orbit, the maximum resolution of the combined instrument would be governed by the maximum distance between the furthest-separated telescopes. You could have an effective telescope the size of Earth's orbit.
A minor caveat to such a technique: you can only see half the Earth at a time, at most. The black hole will be below the horizon for half of the Earth's surface, so there won't be any photons to send back. If the black hole is over the equatorial sky, you'll see 12 hours of each day everywhere; if it's over a pole, you'll be able to see one hemisphere year 'round. TenOfAllTrades(talk) 15:18, 11 May 2006 (UTC)
I don't know the answer, but you may want to look at the Virtual Trips to Black Holes and Neutron Stars page. – b_jonas 20:22, 11 May 2006 (UTC)
Yeah, I imagined something like a VLA system orbiting the earth, probably a handful of independant systems simultaneously measuring other phenomenon in order to help clean up the image. I didn't really imagine angular resolution would be a problem; I figure intelligent sensors will overtake physical lenses in terms of accuracy and usefulness in the future. I always thought as a kid that it'd be so cool to be able to look into a telescope and see the top of the heads of historical figures, even prehistorical humans. Though I guess a much more realistic first step would be to manage some pictures of extra-solar planets first.  freshgavinΓΛĿЌ  00:07, 12 May 2006 (UTC)
Not sure that I understand Freshgavin's question, but according to general relativity, light rays passing very near an ultracompact object such as a black hole can wind around several times before escaping. That means that in principle, if you were using your rocket engines to hover over a black hole, you'd see concentric annuli, containing multiple images of each star in the night sky, around a dark disk. This dark disk would be not the optical "image" of the event horizon (r = 2 m for a [[Schwarzschild metric|non-rotating black hole), but rather (sort of) the "image" of the photon sphere (r = 3 m for a non-rotating black hole). Distant obervers can and do observe "weak lensing": light rays bent slightly by a black hole, but not winding multiple times around the photon sphere. This might sound comparatively boring but in fact it is spectacular. However, gazing at a distant black hole would not be a practical way to examine the back of your own head, if that was the question!---CH 10:55, 16 May 2006 (UTC)

digestion[edit]

recently,i have undergone a lot of religious fastings which lasts for more than 8hours/day.In such a case,how come my body does'nt produce HCl and start digesting the walls of my stomach?

thank you

Your stomach is always producing HCl, whether you've eaten or not; see the article on gastric acid. There are things which can disrupt the system and cause, say, gastric ulcers, but as far as I can tell fasting isn't one of them. You may also be interested in Fasting#Physical effects of fasting. —Zero Gravitas 08:39, 11 May 2006 (UTC)
In the absence of food, your stomach produces less acid, but still enough that it would harm the stomach were it not for your stomach's protective lining. Some cells forming this lining produce a bicarbonate-rich mucus that coats the inner surface of the stomach and buffers the acid. --David Iberri (talk) 18:34, 11 May 2006 (UTC)
8 hours a day isn't very long to go without food for, you would be desperately unlucky to have any effects of this. Keeping in mind other animals (eg. Lion) eat once or twice every several days. Also remeber that the concentration of HCl in the stomach, to my knowledge is only 0.1mol/dm³. Philc TECI 22:20, 11 May 2006 (UTC)
True, eight hours isn't that long. But what do you mean "only 0.1 mol/dm³"? That much acid gives a pH of 1, which is pretty harsh. FWIW, gastric juices are closer to pH 2, which means the acid concentration is closer to 0.01 M, even lower than what you suggested. Still, this would be very harmful to the stomach if it didn't have its protective gastric mucosa. --David Iberri (talk) 02:26, 12 May 2006 (UTC)
Maybe but no acids would be great for you if they were in contact with you for your entire life, the only was on a scale of concentrations, not only acids, so on the grand scale of live the universe and everything, a conc of 0.01mol/dm³ isnt very large, given that pretty much everything is higher than that.... Philc TECI 17:46, 15 May 2006 (UTC)

light[edit]

what is the difference between color of light and color of pigment?

--thanks!

There is a lot of information in colour and articles linked therefrom. I think you are basically refering to colour mixing. Light adds its colours - eg a TV screen has red, green and blue dots which when all turned on appear as white. Pigments are filters and remove colours from light, so cyan, magenta and yellow pigments absorb light which isn't cyan, magenta or yellow. If the light passes through/ refelcts from all three pigments then all get absorbed and you are left with no light or black. -- SGBailey

stress-buster![edit]

can stress actually lead to miscarriages in pregnant women?

There's been a good deal of research on the subject. See here for a good summary. GeeJo (t)(c) • 09:30, 11 May 2006 (UTC)

pressure on human body[edit]

ok, i know this may sound something of an essay question, but its not, i'm a uni student and any kind of help would be great, even if its just what to search for as every obvious thing i have searched for has not come up with the answer i am looking for. what would be the effects of pressure on coordination in the human body? thanks skye

Once you reached a high enough air pressure, nitrogen narcosis would set in, reducing your coordination in the same manner as alcohol. The effects would increase in proportion to the pressure and time spent in the environment. GeeJo (t)(c) • 09:24, 11 May 2006 (UTC)

Archiving[edit]

First, is there a RD:Wikipedia? I think that having it at the top of the RD page would be nice. Second, is there a proper way to archive talk pages? --Kainaw (talk) 12:43, 11 May 2006 (UTC)

Wouldn't that just be the Wikipedia:Help Desk? As for the second, doing a page move, rather than a cut-and-paste, preserves the edit history of a talk page. I think that's preferred. — Lomn Talk 12:54, 11 May 2006 (UTC)

thanks heaps

Thanks also! --Kainaw (talk) 13:24, 11 May 2006 (UTC)
I just found Wikipedia:How to archive a talk page. It didn't come up in the search. I think the Wikipedia search has been rather flaky recently. --Kainaw (talk) 13:58, 11 May 2006 (UTC)
Recently? It's been my experience that the search function here has always sucked. Better to use google. -lethe talk + 09:28, 12 May 2006 (UTC)

How to change Media player Icon[edit]

I've changed my default media player from windows to Jet Audio, but the Icon still remains as windows media player. How can I convert it to Jet Audio Icon? mp3 files are played via jet audio,.but its icon is media player !!

Are you talking about the icon displayed for individual MP3 files? If so, do the following:
1. Right-click an MP3 file icon, then click Open With.
2. If Jet Audio is shown in the Open With list, click it, or use Browse to find it
3. Tick the "Always use the selected program" check box.
4. Click OK.
If that's not what you need, please post again. Feel free to suitly emphazi. --LarryMac 15:52, 11 May 2006 (UTC)


  • 'I've already done the above steps. Mp3 files are played via JetAudio but Mp3 Icons are media player. need to change that to jetaudio icon.
Try: <Start> - <Settings> - <Control Panel> - <Folder Options> - <File Types> - select the registered file type - <Advanced> - in Edit File Type, select <Change Icon> and browse to your JetAudio directory to pick up the icon - click <OK>, etc. --Seejyb 21:59, 11 May 2006 (UTC)

physics-Light[edit]

Does the sparkling of a diamond and twinkling of stars have anything in commom?

thanks a lot

Nope. Diamonds (and other sparkling transparent substances) act as prisms. Stars twinkle as a result of atmospheric distortion (in principle, the same effect as wavy "heat lines" over a grill). — Lomn Talk 14:25, 11 May 2006 (UTC)
Well, I guess they both twinkle:) But seriously, other than that, not much. Also, in my opinion one of the major differences is that stars give off light while diamonds simply, as Lomn says, act as prisms. --Think Fast 01:15, 12 May 2006 (UTC)
Further thoughts on this question. Here is another difference between these two 'experiences': If the position of the light source, the diamond, and the eye are absolutely fixed, there is no 'sparkling'. The appearance of sparkling arises from the slightest motions of the diamond, that presumably offers a large number of faces and opportunities for internal pathways to the incoming light. On the other hand, the light output of a star may be actually quite constant, and if one looks at stars from, say, the Space Station, they do not twinkle. In this case, it is the result of the transmission of light through the atmosphere, itself subject to turbulence and thus density fluctuations, that gives the appearance of sparkling. --Michel M Verstraete 22:19, 12 May 2006 (UTC)

Mac vs PC advocacy - user interface[edit]

OK, I realise this is a minefield. I've read Apple evangelist, Operating system advocacy and others, and they don't really address my question, which is: what is it specifically about the user interface that Mac users find preferable to Windows? Do they think it's easier to find, copy, rename or delete files on a Mac, for example? To switch between open applications? Do they find the Mac's Dock easier to use than the PC's taskbar, and if so why? I'm not interested in issues such as speed, security, architecture, etc. Just these kind of user interface issues. As an example, someone once pointed out that the menu list across the top of the screen is easier to use on a Mac because it's right at the top of the screen, so you can slam the mouse up there and just hit it, whereas with Windows you have to point to it more carefully because there's that blue line across the top. That's the kind of comparison I'm interested in. And by the way, I'm a Mac user myself :) --Richardrj 14:00, 11 May 2006 (UTC)

Ooh. Hmm. Although I am mainly a Windows user, it's Mac OS that I truly love to use. I would say the best feature is Exposé, because it's such a time-saver - hit a key and all your windows show up in thumbnail size and you click on the one you want. Compare that to the slow process of alt-tabbing in Windows. Additionally everything... just works. That's the only way to describe it. I think it might be the way all programs integrate so smoothly with the shell so you always know what everything does - there's no nonstandard "Open file" dialogs. Oh, the "Open File" dialog is great because it shows the contents of a folder and its parent folder at the same time. And the Finder shows all the drives and important folders on the right at all times. Also, Documents go in Documents, Music goes in Music, and so on. Compare that to Windows, where things can get saved anywhere.
It's been said that the Mac's long-lamented lack of a second mouse button is actually a bonus, because stuff doesn't get hidden away in context menus. I don't know if that's true - I think it's just a hinderance really.
But that's my ramble over. Sum0 14:33, 11 May 2006 (UTC)
I pretty much have to agree with what Sum0 has said. Everything works so much better than on a PC, and it looks so much nicer too. All the little extras like the dock magnifying, the genie effect when you minimise windows, dock icons bouncing as they load or to notify you of stuff... they just make the experience so much more pleasant and enjoyable. To be hinest, it's undescribable. --Saxsux 19:17, 11 May 2006 (UTC)
The other awesome thing about Mac OS is the way that, if you want, the OS works like a toaster, or a TV, or a DVD player - it's an appliance, you don't need to worry about drivers or memory or paging or the "computery" bits. And yet unlike a toaster, you can "take the panels off" and underneath there's a proper, powerful Unix heart, which the technically minded can mess around with (I once met a Linux geek who, despite not being a Mac user, knew exactly what to type in the console). So it's fun to mess around with as a geek, but at the end of the day it still works. Unlike other OSes, which tend to break if you stick a spanner in. Sum0 22:09, 11 May 2006 (UTC)
I've concluded that OS X is very good at abstraction. Like Sum0 and Saxsux have pointed out, it looks very nice, things go in obvious places, etc.
But for me, for reasons I'm still figuring out, working with OS X gets annoying after a while. I should say that while I've never owned a modern Mac (and consider myself a PC partisan), I've used OS X, on and off, since the Public Beta, and I'm using a Mac right now (school computer lab). But I can certainly see the strengths of the OS X approach, and I recommend Macs to people other than myself. - mako 00:00, 12 May 2006 (UTC)
Exposé, the dock, Mac OS X, Unix underneath: these are all pretty new. But people have always loved Macs, and some people still yearn for Mac OS 9. So there must be other reasons than all the new gadgets people have been mentioning. (By the way, is there a trick with context menus? The Mac seems to have just as many, but because I don't have a right mouse button, I have to Alt+click. Having to use two hands doesn't seem an improvement, but I'm probably missing something). Notinasnaid 07:58, 15 May 2006 (UTC)
You can hold down the mouse button for a second or two to get the context menu. I don't have any experience with older versions of Mac OS, but if I had to guess I'd say it's because Mac OS is less technical than Windows. No messing about with drivers, no incompatibilities, etc. (Which does have its disadvantages - lack of upgrade potential, for example). Sum0 08:27, 15 May 2006 (UTC)

Great black-backed gull vs. Umbrella Cockatoo[edit]

This was a question that came up on rec.pets.birds a while ago (I found it interesting anyway). Umbrella Cockatoos have a reputation for being vicious, ill-tempered, quarrelsome and generally 'difficult' birds. If one of them was to go up against (arguably) the UK's most vicious, ill-tempered quarrelsome bird, the Great black-backed gull in a fight - which one do you think would win? Like with the man/bear Q. above, assume that there are no outside variables and neither bird was intimidated by the other's posturing, i.e. they both just got stuck in and the feathers started to fly - just a straight one-on-one fight until one of them couldn't fight any longer. --81.79.226.227 14:12, 11 May 2006 (UTC)

I hope you are not contemplating some kind of avian WWF! Like people, birds generally prefer to try to get their way by bluff or ritualized conflict (at most) rather than mortal combat. In nature, fights to the death between well matched contestants are fairly rare.---CH 11:01, 16 May 2006 (UTC)

Program For Text Translation from Arabic to English[edit]

Please I search for Program(software) to translate text from Arabic to English ?

Perhaps one of the links returned from this Google search would be useful. --LarryMac 15:45, 11 May 2006 (UTC)
There is a great site link title that will allow you to easily transilate for free once you get an account. --Welcometocarthage

autogeneic bone marrow transplants[edit]

What is the point in an autogeneic bone marrow transplant? Could you use this for leukemia, returning only the non-cancerous stem cells? --Username132 (talk) 16:15, 11 May 2006 (UTC)

One of the primary benefits is that autogenic transplants reduce the risk of graft-versus-host disease. Their use isn't limited to patients with leukemia; such transplants are likely to be considered in any disease that eliminates one's immune system. Regarding your second question, it is not currently possible to screen for and transplant only those stem cells that are non-cancerous. The major obstacle is that there is no way to determine with certainty whether a given cell is or will become cancerous. --David Iberri (talk) 18:14, 11 May 2006 (UTC)
Can you culture them and see which ones don't grow like cancer?
Also, the article says "Leukemia patients who develop graft versus host disease, particularly chronic GVHD, after an allogeneic transplant have a lower risk of their leukemia relapsing than those who do not develop any GVHD" but don't they also have a concomitantly higher risk of death by GVHD? --Username132 (talk) 20:10, 11 May 2006 (UTC)

Crystals form better if cooled slowly.[edit]

The bone marrow transplant article says "To cryopreserve HSC a preservative, DMSO, must be added and the cells must be cooled very slowly in a control rate freezer to prevent osmotic cellular injury during ice crystal formation." but I think slow freezing promotes crystal formation. --Username132 (talk) 16:30, 11 May 2006 (UTC)

DMSO, a very common cryoprotectant, acts to suppress the formation of ice crystals. Instead, it encourages vitrification of the water. By forming a glass rather than a crystalline solid, you avoid the mechanical damage due to pointy ice crystals.
Our article on cryopreservation gives a good outline of the considerations involved in freezing cells or tissues. TenOfAllTrades(talk) 19:17, 11 May 2006 (UTC)

In general, slow cooling leads to a small number of large crystals, while rapid cooling leads to many tiny crystals. However, based on the previous answers, this is not true in this particular case. StuRat 19:26, 11 May 2006 (UTC)

Rule of thumb: Slow Cooling: Less intracellular ice (good) but more osmotic imbalance (bad). Fast Cooling: More intracellular ice (bad) but less osmotic imbalance (good). So you find the best compromise:
For animal cells a constant controlled cooling rate of 1°C per min seems the best compromise, but the freezers are expensive, so techniques using mechanical freezers and different cryoprotectant strategies are being investigated for a usable cell survival rate at a lower cost. While a Good Survival may be 80%, a lower survival could be Clinically Usable. --Seejyb 22:16, 11 May 2006 (UTC)
As far as rocks go, the slower the cooling, the larger the crystals. --Think Fast 01:17, 12 May 2006 (UTC)

Ammonia[edit]

Ammonia lone electron pair.svg

In the image on the right, what does the line going up with the two dots mean? Thanks, Kilo-Lima|(talk) 17:00, 11 May 2006 (UTC)

That's a lone pair of electrons. The line is optional (you may also encounter ammonia as :NH3). Presumably, the line helps illustrate the tetrahedral orientation of hydrogen atoms and lone pair around the central nitrogen. --David Iberri (talk) 17:14, 11 May 2006 (UTC)
It's not quite tetrahedral. The lone pair of electrons have a large enough density of charge to force the hydrogen atoms closer together. Tetrahedral would be 120 degrees but this according to the image is 107 or 102 - I think there might be a special name for this scenario but it's be three years since I completed that course... :( --Username132 (talk) 18:03, 11 May 2006 (UTC)
Just a minor correction: the angles in a tetrahedron (such as methane) are 109.5°. In ammonia it is 107° - a slight distortion. --Ed (Edgar181) 18:13, 11 May 2006 (UTC)
It's still considered tetrahedral despite the minor deviation from 109.5°. I don't believe the 120° bond angles you mention have anything to do with a tetrahedral geometry. Those angles would be common in other molecules such as the sp2-hybridized carbons in alkenes. --David Iberri (talk) 18:21, 11 May 2006 (UTC)
What I want to know is, since the hydrogens each have a partial positive charge, they should repel each other and the angle between them should be more than the 109.5°, not less. The lone pair of electrons at the top should have a partial negative charge and attract the hydrogens so the angle there should be less than 109.5°.
Read up on VSEPR theory. Your rationale is incorrect. First, the partial charge on the hydrogens is relative the nitrogen atom. Now, does the lone pair orbital have a negative charge relative the nitrogen atom? No. They belong to the nitrogen atom. --BluePlatypus 11:28, 12 May 2006 (UTC)
The lone pair is closer to the electrons making up the N-H bond than to the H-atom. Consequently the bondling electrons are repelled stronger than the hydrogen atom is attracted. Dr Zak 00:22, 14 May 2006 (UTC)

The correct term for the shape of the molecule is pyramidal. The electron pairs dominate the repulsions, and the tiny H atoms are insignificant in this respect. So the short, fat lone pair repels the longer, thinner bonding pairs (each with an H atom at the end) more than they repel each other, forcing the three bonding pairs slightly inwards to an angle of 107 degrees. The electron pairs can therefore be described as having a distorted tetrahedral geometry, but the molecule is pyramidal. X-ray data will not show up the lone pair - it is not part of the shape of the molecule itself.G N Frykman 21:26, 11 May 2006 (UTC)

The presence of lone pairs also explains why a water molecule is bent, and not linear like carbon dioxide, for example. Molecule shape gives an explanation in terms of electron orbitals. Gandalf61 08:33, 12 May 2006 (UTC)
One little thing I'd like to add is a little caveat: as a heuristic, you can pretend as if the lone pair is more repulsive than a typical bond. However, if you do ab initio calculations for the electron density, there really isn't a lobe where the lone pair is. For example, in water, there aren't those "rabbit ears" sticking out. --HappyCamper 00:58, 14 May 2006 (UTC)

flowchart for the manufacture of Dichlorodiphenyltrichloroethane,DDT[edit]

Hello,

 I will be very greatful if anyone could draw the flowchart for the manufacture of DDT for me.
                                    Thanks
                                  ----------
You may be interested in the answers from the last time you asked this question. --Kainaw (talk) 18:00, 11 May 2006 (UTC)

Internet data exchange[edit]

How much data is exchanged on the public Internet daily? 134.215.197.210 19:26, 11 May 2006 (UTC)

I doubt that there's any way to give anything aproaching a definitive answer to this question, but traffic stats from the London Internet Exchange show an average data rate of about 100Gbps[37] (which works out at approx 1PB per day) and that is only traffic going through LINX. -- AJR | Talk 00:03, 13 May 2006 (UTC)

Dodgy Bike Gears[edit]

On my old bike I'd change gear and it would always take ages for the chain to move across and I'd get a constant clickety sound. Even when it moved over, it would sometimes carry on clicketing like it wanted to be on another sprocket. Why?

Also, on dutch omafiets, the chain is usually covered by some fabric thing - what's that about?

If your shifter isn't aligned correctly, it tries to shift the chain near the gear you are selecting. Since it isn't put in the correct position, it just sort of clanks around between the gears. --Kainaw (talk) 20:26, 11 May 2006 (UTC)
I assume you're talking about an external derailleur shifting mechanism rather than an internally-geared hub. If this is the case, the alignment of the jockey pulley of the derailleur with the cogs on the freewheel may be innaccurate. This is especially the case with the "indexed shifting", where the shifter "clicks" into the gear position rather than being continuously hand-adjustable. The alignment can be modified by adjusting screws on the derailleur and/or barrel adjusters on the cable levers.
Another possibility is that your chain is worn, or "stretched." In this case, the effective pitch between the links has increased so that the chain links do not seat easily in the teeth of the chainring or rear cogs. Alternatively, your chainring and/or cogs are excessively worn. In any case, replacement of the worn part should help.--Mark Bornfeld DDS 20:52, 11 May 2006 (UTC)
Shifter cables tend to lengthen over time and with use, so a derailleur that was in adjustment is no longer in adjustment. There's a little knob called a "barrel adjuster" where the cable goes into the derailleur housing. By twisting it clockwise or counterclockwise, you can get it back into alignment. See this article on ehow.com for details. --Elkman - (talk) 20:54, 11 May 2006 (UTC)

Circular Motion[edit]

At what minimum speed must a roller coaster be traveling when upside down at the top of a cirlce if the passengers are not to fall out. Assume a radius of curvature of 9.6m.

I've done this about 5 different ways and gotten different answers each time. The example below is one I think may make the most sense....I don't have the answer to this problem so if someone could verify whether I got it right or not. Thanks.

 \Sigma Fc = \frac{mv^2}{r}
 FN + FG = \frac{mv^2}{r}
 2mg = \frac{mv^2}{r}
 2g = \frac{v^2}{r}
 v = \sqrt {2gr}
 v = 13.72

C-c-c-c 20:54, 11 May 2006 (UTC)

Almost. See circular motion; it's just
 a = \frac{v^2}{r}
(where a = g in this instance; the rollercoaster can't be accelerating at 2g downward)
 v = \sqrt {gr}
Zero Gravitas 22:01, 11 May 2006 (UTC)
Haha that was one my "five" answers .... Thanks! C-c-c-c 22:10, 11 May 2006 (UTC)

car's sweet spot[edit]

i recently read in news scientist that there was a piece of US legislation that forced car companys to make there cars more effiecent at 55mph, ie the sweet spot where the cars runs the most effiecently, now is there a similar law in the UK and if so whats the speed? Colsmeghead 21:15, 11 May 2006 (UTC)

I've never heard of any such law. Searching the Library of Congress for anything with "55 mph" only turns up one bill: Fuel Economy Truth in Labeling Act. It notes that the EPA allows automakers to use a highway speed of 48mph when measuring "Highway MPG". It wants it increased to at least 55mph since most states allow speeds of least 65mph on highways. --Kainaw (talk) 00:54, 12 May 2006 (UTC)
There was also a law or regulation requiring that the speedometer have an emphasized marking (numbers larger or in a different color) for 55mph. --Serie 20:44, 12 May 2006 (UTC)
ok i made mistake its 27.5 miles per gallon (55mph was from soemthing esle in the article), done by presdient carter in 1975 and called the coporate average fuel effciency standardColsmeghead 22:46, 12 May 2006 (UTC)

Electrolysis of Water[edit]

I am seriously confused about some key elements in this process. First when water undergoes electrolysis then can the oxygen mix with the hydrogen without turning back into water and if it can why cant that gas be used in cars?

The oxygen and hydrogen can indeed mix together without reacting. In order to react there has to be a source of activation energy, such as a spark. There are many reasons why a hydrogen-oxygen mixture would be a bad fuel for cars. One is simply that oxygen is readily available in Earth's atmosphere, so it would be a waste of space to carry it along. Another is that it would be dangerously explosive, especially at the high pressure required to store it in a reasonable amount of space. Many people are working on designing hydrogen vehicles, but so far no one has conquered this problem of energy density. —Keenan Pepper 00:03, 12 May 2006 (UTC)
Oh, we are considering the problem, trust me - and, as you correctly pointed out, it's a bit of a pain in the backside! Hydrogen is so darn light that it either needs to be kept as a liquid (so you'd be driving around with a massive, insulated tank at about -250°C - oh boy!) or as some kind of molecular combination... it's a problem, and it's being worked on. I will be very curious as to the eventual solution to it...
Under compression Hydrogen can be a liuquid at room temperature. Like in the fuel chambers of rockets. Just for the record, the ice on hydrogen/oxygen powered rockets, is caused by the hydrogen boiling, and isnt because the rocket has been in some collossal fridge. Philc TECI 17:43, 12 May 2006 (UTC)
Erm - isn't it just because the insulation on the tanks isn't 100% perfect, and the outer skin of the rocket is cold enough that water vapour from the atmosphere freezes to it? I don't think I'd want to have any uncontrolled hydrogen boiloff in the middle of a rocket launch... — QuantumEleven 10:15, 13 May 2006 (UTC)
Yes, but thats my point, cold can't spread, as it doesn't exist, it is just the absence of heat, so heat has to be sucked, this energy sucked in by the liquid hydrogen gives a tiny amount of it the energy to boil (like possibly 0.1% of the contents) but the point is compressing a liquid to a level and then allowing to expand a bit (in this case as it is stroed, and then as it is pumped in) causes the ontainer to get very cold, like a deoderant can when you relieve some of the pressure by spraying some. Philc TECI 17:50, 15 May 2006 (UTC)
Also, liquid hydrogen has the para/ortho problem, which can lead to tank rupture.
And for the original question, to see what happens when hydrogen and oxygen get mixed together, see what happened to the Hindenburg. — QuantumEleven 07:44, 12 May 2006 (UTC)
On the other hand, liquid hydrogen and oxygen (which must be kept separate) make great rocket fuel. —Keenan Pepper 00:06, 12 May 2006 (UTC)
As far as I am aware hydrogen is not a resource in abundance on earth, the most viable way to get it would be from water, whivh then means hydrogen would only be viable as a way of storing energy, and not releasing it, as you need to initially split the H2 and O up to join them back together. Philc TECI 17:43, 12 May 2006 (UTC)
Nonetheless hydrogen is the most aboundant element in the universe. Luthinya 21:45, 16 May 2006 (UTC)

May 12[edit]

programmer/software engineer[edit]

what are the big differences between a software engineer and a computer programmer?--orphan frequently 03:21, 12 May 2006 (UTC)

About $15,000 a year. [38] - user:rasd

well, yes, i could have told you that, but i mean actual work wise.--orphan frequently 03:21, 12 May 2006 (UTC)

I suppose a software engineer might do more than just write programs, such as developing the specs, creating database tables, developing an implementation schedule, test plan, and rollout plan, etc. StuRat 03:30, 12 May 2006 (UTC)
Yeah, in general, software engineers do a lot more overall project work. It varies a lot, but you might think of it as a type of senior programming position. In larger projects, computer programmer becomes more the grunt work, whereas in smaller projects, "programmers" will do the exact same duties and will probably be paid similarly if not more than the software engineers. Seriously, though, the distinction is not always clear. When I did some undergrad study in computer science, the answer I gave you was more or less the same answer I got from two professors. Software engineer is (or at least was back then) a title that senior programmers gave themselves so they didn't look somehow inferior to other kinds of engineers. - user:rasd
A true software engineer is a licenced professional qualified to write software that involves risk to humans. Usually, however, it's just a fancy (and technically incorrect) name for a computer programmer, particularly one who designs software in addition to simply writing the actual code. Peter Grey 04:21, 16 May 2006 (UTC)
Where would that be the case? Neither our software engineering or Professional certification has any mention of that that licensing. Rmhermen 16:33, 16 May 2006 (UTC)
In Ontario, claiming to be any kind of engineer without the professional licence is illegal. But "software engineer" as a job title seems to be fairly common in places that allow informal meanings of 'engineer'. Peter Grey 02:11, 17 May 2006 (UTC)

haha, i have to come up with three careers for a project, anyone got another name, technical director maybe?--orphan frequently 04:06, 12 May 2006 (UTC)

Randomly generating the contents of a Javascript array[edit]

My knowledge of using arrays in Javascript is pretty weak. Basically, I want an easy way to fill out an array with, say, 10 numbers, from 0-9, in a "random" order. So a few possible options would be...

  • MyArray = Array(0,1,2,3,4,5,6,7,8,9);
  • MyArray = Array(7,0,4,5,9,6,8,2,1,3);
  • MyArray = Array(4,6,9,1,3,0,5,2,7,8);

Every number is used once. Now, just to add a little more complication, I'd like to be able to do this for n amount of digits (I did it for 10 up above, but it would be nice to be able to use the same function for 11, or 12, etc.). In every case I will be using the digits from 0-n, and will want each one to be used exactly once.

Is this a foolish desire? Is there an easy way to do it? You don't have to do all the work for me, but pointing me in the right direction would be fine. --Fastfission 05:29, 12 May 2006 (UTC)

I don't know JavaScript. But I would create an array of n+1 digits in the direct 0..n order. Then I'd apply the Knuth shuffle: move through the array from beginning, swapping the current element with a random one. That should give a random array with unique digits. Some pseudocode:
Declare MyArray of n+1 elements

For i = 0 to n
  MyArray(i) = i
Next

For i = 0 to n
  Temp = MyArray(i)
  RandomElem = int(random(n+1))
  MyArray(i) = MyArray(RandomElem)
  MyArray(RandomElem) = Temp
Next
Hope this helps. –Mysid(t) 05:47, 12 May 2006 (UTC)
I'll give that a shot. I'm not sure I 100% understand how it works at the moment but after I play with it for a bit it should make sense. --Fastfission 12:42, 12 May 2006 (UTC)
That works beautifully. Many thanks. --Fastfission 12:50, 12 May 2006 (UTC)
If (big if) I'm reading Shuffle right, Mysid's algorithm produces biased shuffles. You have to restrict the card drawn to the part of the pack not yet passed through (ie RandomElem >= i), or you end up with n^n execution paths matching on to n! possible outcomes. Something along the lines of
                             RandomElem=i+int(random(n+1-i))
should work properly (I think). --193.38.88.6 15:49, 12 May 2006 (UTC)
You're correct! Great that you noticed. I seem to have skipped that part when reading. –Mysid(t) 16:55, 12 May 2006 (UTC)
The way I would implement it in JavaScript:
n = 10 // number of elements desired
r = 50 // random numbers can be from 0 to (r-1)
randarray = new Array(n);
i = 0 // temp counter
while (i < n) {
randarray[i] = Math.floor(Math.random()*r); // Math.random() produces pseudo-random number between 0 and 1
i++;
}
// randarray should now have random number elements.
Note that these "random" numbers are merely pseudorandomly generated ones. Apart from that, I tested it and it works fine. Enjoy. -- Daverocks (talk) 13:23, 15 May 2006 (UTC)
Erm, I'm not sure that's what Fastfission wants -- the array must include all digits between 0 and n-1 once only, but in a random order. I suppose you could sort the array and then assign the sorting indices back to the original place in the array that the number came from, but that'd be much more computationally expensive than the shuffle algorithm. --Bth 07:18, 16 May 2006 (UTC)
Oh, right! Sorry about that. Heh, you can use Mysid's algorithm then. :) -- Daverocks (talk) 08:37, 16 May 2006 (UTC)

silicon oil[edit]

is silicon oil bad for baby skin?

Nasty stuff, for industrial use only. See silicone, and this: [39] --Zeizmic 12:56, 12 May 2006 (UTC)

Baby no longer slippery? Maybe the first signs of rusk? What he (or she!) needs is oiling! But forget cheap silicone oils. Buy Baby oil. Babies just love it! Baby oil. Available at all good corner stores.

If you accidentally got silicon oil on a baby's skin, I would advise you to contact poison control just to be on the safe side. --Ginkgo100 19:33, 12 May 2006 (UTC)
You lot are chasing up spooks. Silicones are common and safe ingredients of many cosmetics. They do aid in softening skin. They are remarkably nonreactive. Allergies are virtually unknown. Not known to be carcinogenic. Silicone used in any body "oil" would be FDA tested and approved (as are those used in hair care products, cosmetic creams and pastes). If one is using industrial or home lubricating oils, the issue is different, but the problem is more with solvents and propellants than with the silicone compound itself. So don't use stuff not designed for human skin use, but those that are approved for skin use are safe for babies. Has anyone here ever had problems from accidentally getting lubricating silicone spray on their hands, not related to the propellant used? Why would plant oils be safer than silicone oils? You have probably given your baby silicone orally, without knowing it, as part of the treatment for "winds"--Seejyb 21:21, 12 May 2006 (UTC)
Peeve alert: Please distinguish between silicon and silicone. There's no such thing as "silicon oil", unless ordinary oil is "carbon oil". Silicon is a solid, metallic in appearance and to the touch (though not technically a metal). --Trovatore 21:25, 12 May 2006 (UTC)

global warming[edit]

has the world really been warming over the past 20-30 years?what are the consequences?

thank you

Yes, the average temperature on Earth has been steadily rising over most of the 20th century, and the scientific consensus is that this is caused by human activity. Our articles on global warming and climate change cover this very well. Note that I said average temperature has been increasing, this does not preclude some local cooling. The consequences of this will most likely be rising sea levels (as the polar caps melt, quite a few Pacific islands will probably disappear in the next 50-100 years), more violent weather (more storms, blizzards, hurricanes), longer and more intense periods of drought and flooding... I could go on. Our article on effects of global warming covers this quite nicely. — QuantumEleven 07:39, 12 May 2006 (UTC)
The scientific consensus is the reason for global warming is controversial. The political consensus is this is caused by human activity. The climate is too complex for us to understand without a lot of research, and the research is complicated even more by being infected with politics.
Just for the record: In addition to the excellent coverage within Wikipedia, you may want to consult the official reports of the Intergovernmental Panel on Climate Change (IPCC) which are available from http://www.ipcc.ch/. The full report is extensive and exhaustive, but there are 'Executive summaries'. Volume 2, in particular, deals with the expected impact of climate change. By the way, the Fourth Assessment Report is currently in preparation and should be released in 2007. --Michel M Verstraete 22:33, 12 May 2006 (UTC)

Electricity from Exercise Bike[edit]

People have said that you can ride an exercise bike that is properly equipped, and by doing so you can pour energy into the system and get reinbursed by the electric company. They even say that if you pour in more energy than you use, the electric company has to pay you money. Sounds cool, does anyone know how to go about doing it, if it is possible. Thanks, Chuck(척뉴넘) 07:54, 12 May 2006 (UTC)

This reminds of an episode of Catdog.. Jayant,17 Years, Indiacontribs 07:57, 12 May 2006 (UTC)
I am not sure about the electric company but you can definitely generate some electricity from the exercise bike. Basically the bike will have some mechanical device to introduce friction so as to make you do the work. In place of this friction device, you can put a dynamo. When you pedal the bike, the dynamo will generate electicity. This may not be sufficient to light up your home but you can possibly charge some batteries. Even if you tie up with the electric company, I don't think the reimbursement will be substantial, considering that you generate a very small amount of electricity -- Wikicheng 09:09, 12 May 2006 (UTC)
Ask your local power company if they offer net metering. There may be rules about it, such as what power production methods are allowed, you may need to promise to deliver at least a specific hour-wattage annually, you may need to pay (part) of the construction of necessary equipment, etc. Consult your local legislation and your power company. Weregerbil 10:49, 12 May 2006 (UTC)
This is from an article I recently used in a paper on global warming: "Got some solar power to sell, or are you finding you don't have enough to keep the lights on at home? GridPoint (www.gridpoint.com), an energy management appliance maker, is developing better ways to manage your homemade renewable energy. The company recently received a "Most Innovative Product" award from Green Builder Magazine for its battery-backup device for solar powered-homes, GridPoint Connect. The system plugs into your home's electrical system, balancing loads and protecting against power surges. GridPoint Connect also sells your unused juice back to the grid."--Chris 14:58, 12 May 2006 (UTC)
Depending on how athletic you are, you will probably only generate 80-120W of continuous power on your bike - that's enough to light one or two lightbulbs, and nowhere near enough to run a computer or a fridge, let alone a power-hog like an oven, hotplate or hair dryer. I doubt you will be able to make a significant dent in your electricity bill this way. But, it can't hurt to ask. — QuantumEleven 14:59, 12 May 2006 (UTC)
Let's see.. Running a marathon uses about 15 MJ. That's 4.1 kWh (if you could turn that all into electricity with 100% efficiency). Given a going rate of electricity of about 10 cents a kWh, that's almost half a dollar! Now subtract the cost of food it'll take you to sustain that kind of activity. --BluePlatypus 15:02, 12 May 2006 (UTC)
You'd be lcuky if you made enough electricty to work a fan and keep you cool. Philc TECI 17:36, 12 May 2006 (UTC)
I think the reason that some people think you can get a lot of electricity from a bike is because there are bikes set up so that as long as you keep peddling at a certain speed (or more), the television works. If you slow down, the television cuts off. If you don't know what is going on, you'd think the bike powered the TV. That is not the case at all. The bike powers a relay (an electrical switch) that controls the electicity going from the power outlet on the wall to the television. When the bike wheel moves, the switch closes and the TV turns on. When the bike stops, the switch opens and the television turns off. --Kainaw (talk) 17:40, 12 May 2006 (UTC)
Generally, unless you have a major waterfall in your back garden, or live in Sellafield, or have discovered cold fusion, the cost of generating the power would be greater than any possible returns. smurrayinchester(User), (Talk) 19:57, 12 May 2006 (UTC)
"you will probably only generate 80-120W of continuous power on your bike", so let's say 100W. If you ride for 10 hours, that's 1 kWh, which costs me 11 cents, according to my bill. That shows you what a great deal cheap energy is. Please help the good deal last as long as possible; please do not waste energy. So muscle power is tiny, compared to electricity use; that's not a practical way to go. "Generally, unless you have a major waterfall in your back garden, or live in Sellafield, or have discovered cold fusion, the cost of generating the power would be greater than any possible returns." WRONG. Wind and solar can feedback into the grid at high peak times. Case in point: http://www.solarwarrior.com/ 27kW system, feeds into the grid during the day, they get paid; grid charges electric cars at night, They pay NOTHING , net, for electricity , including NOTHING for their cars. (Other than capital costs, of course.) But their use of global oil for their cars is zero, their energy independence, total. Electric companies should be REQUIRED to offer net metering. --GangofOne 02:06, 13 May 2006 (UTC) Lower end systems: http://www.homepower.com/magazine/guerrilla.cfm --GangofOne 02:44, 13 May 2006 (UTC)

Astrophyton darwinium[edit]

"Astrophyton darwinium" (Gorgonocephalus sp.)

What is the modern name of Astrophyton darwinium? Googling for the species name returns zero results (you get a few more on just the genus "Astrophyton"). The creature features prominantly on plate 70 in Ernst Haeckel's Kunstformen der Natur (1904) (see the Commons page for all the beautiful plates). The name is shown in the associated text [40] if you want to check it for typos, or if you can read German and want some clues. Note that Haeckel himself is the authority on the name. Any help appreciated. It's been bugging me for a while. (Note that Wikipedia's article on Astrophyton is for a genus of cacti, and not basket stars) —Pengo 07:56, 12 May 2006 (UTC)

...hello? —Pengo 00:59, 14 May 2006 (UTC)
Could it be in class/subclass euryalidae/euryalida ? Basket stars are a subset of brittle stars. Unfortunately, Wikipedia doesn't have much on them. But I think these pics match yours: [41] [42]. StuRat 04:39, 14 May 2006 (UTC)
Perhaps it's a gorgonocephalus verrucosus: [43] StuRat 05:03, 14 May 2006 (UTC)

Supernovae[edit]

Can I get a detailed explaination of observations accompanied with the Supernovae(like mag, and explaoination of types, naming etc.)? Contact : [email removed for spam prevention]

Did you try supernova? It's a bit short on exact details of the luminosities involved, but the rest of your question would seem to be covered there. --193.38.88.6 09:56, 12 May 2006 (UTC)


Supernovae[edit]

Can I get a detailed explaination of the observations accompanied with the finding of Supernovae (like the value "mag", and explaination of types of Supernovae, naming etc.)? Contact : <Email Removed>

Please do not post your e-mail address on a public forum. And you might wanna check out the Supernova article, if thats what you are searching for. Jayant,17 Years, Indiacontribs 09:38, 12 May 2006 (UTC)
Woops, I've just seen that this guy's repeating himself. Sorry. --193.38.88.6 09:56, 12 May 2006 (UTC)

Bomb[edit]

which of the following 3 bombs, kills only humans(living organism) but has little effect or damage on buildings & other properties? A. neutron bomb B. Hydrogen Bomb C. Atomic bomb --the preceeding unsigned comment was added by 196.200.102.42 at 10:32, 12 May 2006

A neutron bomb has been said to kill only humans but leave buildings intact. This seems to be disputed, though. See the article. (But the correct alternative is A.) –Mysid(t) 10:24, 12 May 2006 (UTC)
We cover hydrogen bombs and atomic bombs in the article on nuclear weapons. --Howard Train 10:31, 12 May 2006 (UTC)
Neutron bombs are designed to have lots of radiation (which kills living organisms) and relatively little blast/fire effects (wouldn't harm as many buildinging as "regular" fission or fusion weapons). --Fastfission 12:37, 12 May 2006 (UTC)
Neutron Bombs do have increased radiation, but I am not aware that they have a smaller blast than a standard fission bomb of the same size. Philc TECI 17:33, 12 May 2006 (UTC)
In the future, it's recommended you do your own homework. But thanks for asking. --Ginkgo100 19:37, 12 May 2006 (UTC)
For all of them, it depends on the size of the explosive and where it's detonated. Peter Grey 04:24, 16 May 2006 (UTC)

Frequency ramp generator?[edit]

I'm not sure if "frequency ramp generator" is the right term, but I need to build a circuit that produces a signal output whose frequency increases linearly as a function of time. Using a function generator and op-amps, transistors, timers etc, is there a simple way to build such a circuit? Thanks. -Wiccan Quagga 12:24, 12 May 2006 (UTC)

Why not take a simple VCO and connect it to the output of integrator on opamp (feeding constant voltage to this integrator)?--Ring0 13:30, 12 May 2006 (UTC)
I believe what you are looking for is a "sweep generator". Try Google. --68.238.243.228 01:11, 19 May 2006 (UTC)

Animals without dividing cells[edit]

I came across the following sentence: "If a constant killing radiation were endured, all living animals with dividing cells would die."

Logical follow-up: are there animals that do not have dividing cells? Are they short-lived? 194.151.6.67 12:41, 12 May 2006 (UTC)

Last I checked all cells divided. Luigi30
Actually, some cells (such are neurons) are too specialized to divide. They are the "end of the line," so to speak. --Ginkgo100 19:48, 12 May 2006 (UTC)

(Ταλκ το mε) 14:01, 12 May 2006 (UTC) Keith Richards --Zeizmic 14:21, 12 May 2006 (UTC)

They wrote it in that way to make the definition of radiation clearer. It would not be good enough to write "... all animals would die." It's just the style of writting the author chose to use. But you are right, all cells reproduce themselves by dividing. --Chris 14:55, 12 May 2006 (UTC)
I'm no biologist, but why would it be no good to write "...all animals would die"? Wouldn't that have been clearer, and avoided the questioner's confusion? --Richardrj 15:17, 12 May 2006 (UTC)
Perhaps the writer meant to specify the reason why animals die under radiation exposure – it disturbs their DNA replication, for instance, so that they can't divide normally. –Mysid(t) 16:52, 12 May 2006 (UTC)

Don't forget red blood cells. They have to be made in the bone marrow because they can't divide on their own. Jonathan talk 14:18, 15 May 2006 (UTC)

Real files to DVD?[edit]

Is it possible to burn Real Player video files (.rm) to DVD and watch them on TV through a DVD player? --Richardrj 14:59, 12 May 2006 (UTC)

Perhaps the only solution is to recode that files to a format supported by your DVD player (every player supports MPEG-2, for example).--Ring0 16:07, 12 May 2006 (UTC)

what is our physical universe[edit]

What's this about oval orbits? I mean, most people can visualise an object moving uniformly in a straight line, unless there is an external influence. Why is it that all orbits are not perfect circles? If an object is moving away from the point of gravitational infulence and there is no friction, (no friction in space, right?) it will tend towards the straight line. Surely the gravitational influence is weaker the further the object is aways from it? Why does it reach a plateau and return (and gain velocity)? I'm not sure the analogy of a rubber blanket, (gravity influencing from below), with balls rolling around a heavier ball makes sense here. What have I missed?

According to Newton's law of universal gravitation the energy of the planet in a star's gravitational field is:E=\frac{mv^2}{2}-G \frac{M m}{r}. This allows three types of movement: elliptic (when the planet lacks energy to go out from the gravitation potential well, that is, E<0), parabolic (when it has just enough energy and no more, that is, E=0) and hyperbolic (when it has more energy, E>0). It can be derived mathematically.--Ring0 16:04, 12 May 2006 (UTC)

Note that an ellipse is not the same as an oval. Ellipses, parabolas, and hyperbolas are conic sections, while an oval is a vague term that can mean many things. StuRat 16:52, 12 May 2006 (UTC)

While the equations prove to him that it's true, I don't think that's going to help him visualize why orbits don't all become circular. Instead of thinking about circular orbits, think of the way things fall back to earth. If you throw something up at an angle and let it drop down (lets pretend there's no air, and no friction), it follows a parabolic path, not a circular one. If you threw the object really far up, so far that on its decent back to the earth it would actually miss it (go over the edge, in a manner of speaking), the parabolic curve would continue around the earth and after a while it may end up in a regular elliptical orbit. Sure the farther the object is the weaker gravity is, but if the object is moving slower than the escape velocity at that point, it won't plane out into a straight line, and it will eventually fall back. In fact, it must be quite difficult to achieve a circular orbit naturally; the object must be travelling at a 90 degree angle to the circumference of the planet and at the exact speed to keep it stable at that height.  freshgavinΓΛĿЌ  17:13, 12 May 2006 (UTC)

Since energy cannot be created or destroyed, a comet for example has two types of ebergu, kinetic energy (KE), and gravitatinal potential energy (GPE), as it falls towards a larger object, eg the sun, the GPE is converted into KE, the more KE it has, the faster it moves, and as it moves away KE is converted into GPE, once all of the energy is GPE, this is the furthest that the comet can go, and it starts to move back towards the sun in a round path, with the sun at one of the focuses. Philc TECI 17:26, 12 May 2006 (UTC)
That's cute, as in: "Ha, Romdyrom equation say, for Ebergu: r = nv3. That right Emhlish?" --Seejyb 23:27, 13 May 2006 (UTC)
Hehe, aww, sorry, that joke was a bit synical... mahwell, ok its energy. Philc TECI 18:53, 14 May 2006 (UTC)

Many thanks Guys. —The preceding unsigned comment was added by 82.24.122.46 (talkcontribs) 00:15, 13 May 2006 (UTC)

Water activity of food and storage at % ERH[edit]

Hi!

If a food stuff has a water activity of 0.70, then it would have an equilibrium relative humiditiy (ERH) of 70% (right?!). But to keep this constant, what ERH would it need to be stored under?

Thanks!

The equilibrium relative humidity ERH of the food is determined when it is made and packaged, it is a description of the indirect technique by which water activity (aw) of the food is measured. The aw and pH are used to predict the potential for bacterial or fungal growth in the food in it's original container / package form. The storage requirement is a separate issue, relating to temperature, moisture and light conditions of the environment, this is neither measured nor expressed in terms of ERH (the latter cannot be determined outside of a sealed container anyway). If food has a high aw, one would usually have to keep it refrigerated to reduce the available free water for bacteria to grow in, or include a preservative. So one does not store food "under an ERH of XYZ" - the aw is already specific to the food itself - but the aw (as derived from ERH) can give one an indication of what special storage conditions are required to help prevent spoilage, or of the expected safe storage period under specific conditions (see equation in water activity). The [FDA] publishes info on the variables affecting bacterial growth --Seejyb 23:41, 12 May 2006 (UTC)

psoriasis[edit]

does psoriasis spread to infants below 3 months of age. is it contagious. does it leave scars which is long lasting. can it be treated by medicine.

Try psoriasis and relax a little. I'm fairly sure it isn't contagious to anyone. Skittle 18:16, 12 May 2006 (UTC)

It is non-contagious, and is a challenge to treat. There are a number of treatments to relieve the symptoms, though. The condition is, according to the article, incurable and lifelong, so it's difficult to speak about leaving scars. Our article on psoriasis has more. –Mysid(t) 18:16, 12 May 2006 (UTC)
See the note at the top of this page. This is not the place for medical advice. Please, please, talk to a pediatrician and/or dermatologist if you're worried. That said, please note that Eczema (ordinary skin rashes), are quite common in babies and that the onset of psoriasis is usually around the age of 10 or later. Here are a few links on infantile eczema from a cursory Google search: [44] [45] --BluePlatypus 17:33, 13 May 2006 (UTC)

Video conferencing[edit]

Can video conferencing increase productivity in meetings? I'm looking for research or testamony.

I love video conferencing with my: juices --Mac Davis 22:00, 12 May 2006 (UTC)
Increase productivity relative to what ? If relative to flying people in from around the world for an in-person meeting, I would say, yes, definitely. If relative to plain old teleconferencing, then only if there is something visual worth seeing. If relative to not having the meeting at all, then that depends on the value of the meeting. Many meetings seem to be a waste of time and productivity, held only because it's on the schedule, not because anyone has anything of value to contribute. For example, my brother was once told to abandon a customer for an emergency meeting on increasing customer responsiveness, LOL. StuRat 22:15, 13 May 2006 (UTC)
Video conferencing is probably more productive than having geographically separated workers not communicating directly. I don't know that it's ever been researched, though. (It's interesting that industries that can't charge meetings to their customers (say, accounting) almost never have meetings.) Peter Grey 05:10, 17 May 2006 (UTC)
I think some meetings are productive, say if a team is working on a group project and needs to meet to figure out who will do which portions. Unfortunately, many meetings seem to be held for no real purpose, such as a work group composed of many people with unrelated job responsibilities meeting weekly. Such meetings tend to be a waste of time and resources. StuRat 06:25, 18 May 2006 (UTC)

What is on the other side of the world from me?[edit]

During a conversation with a friend, we were trying to figure out how you'd answer the topic question. I think you find out your current latitude and longitude; add/subtract 180 to/from the longitude and just flip the latitude north for south; then find out what's at those new co-ordinates. Do we have our algorithm right? --LarryMac 19:04, 12 May 2006 (UTC)

Is it true for the poles ? --DLL 19:09, 12 May 2006 (UTC)
What would you give as the (geographic) latitude and longitude for either of the poles?
Anyway, if our idea is correct, then if I were in my opposite place, I'd be drowning in the Indian Ocean off the SW point of Australia. (...waving to Jack ...) --LarryMac 19:16, 12 May 2006 (UTC)
Hey, Larry, how very thoughtful. I'm flattered that while you're drowning in a vast ocean about 3,000 kilometres away from me, you'd still find time to wave to me. If you survive, get in touch with the guys from Not Drowning, Waving. JackofOz 00:49, 13 May 2006 (UTC)
Very interesting; from where I am (near London), my antipode would be floating somewhere in the Pacific Ocean, some distance away from New Zealand, and close to the International Date Line. Maybe if I crossed the Greenwich Meridian, my antipode would thus cross the International Date Line and thus change a day... Andrew 15:57, 19 May 2006 (UTC)
You are correct. Change the latitude from north to south or vice versa; subtract the longitude from 180 and change it from east to west or vice versa. The point opposite you on Earth is called the antipodes (singular). Yes, this holds true for the poles. The north pole, for instance, is latitude 90° N (longitude is irrelevant/undefined); change to 90° S and you're at the south pole. Of course, this assumes the Earth is a perfect sphere or at least symmetric over the plane of the equator and rotationally symmetric around the axis (I think). http://www.antipodemap.com/ is a cool little page. — Knowledge Seeker 19:33, 12 May 2006 (UTC)
Excellent! That page is exactly what we were looking for. Thanks. --LarryMac 19:37, 12 May 2006 (UTC)
You'll notice from that page the surprising fact that there are very few antipodal points that are both on land. For the vast majority of the world's population, the answer to "What is on the other side of the world from me?" is "an ocean". The only overlap of continents, as shown in the Antipodes article, seems to be parts of Argentina and China. This makes me wonder: is this lack of antipodal continents a coincidence, or the result of some subtle effect of tides or continental drift or something? rspeer / ɹəədsɹ 19:45, 12 May 2006 (UTC)
I'd say it's a coincidence, as most of the Earth's surface happens to be water (which also might be a coincidence). –Mysid(t) 19:56, 12 May 2006 (UTC)
My friend who started all this happens to live in Hawaii, so he's in one of the few other places with a non-oceanic antipodes. --LarryMac 20:00, 12 May 2006 (UTC)
Mmmmh, there seems to be something odd in the Antipodes picture. Everybody in Italy know that New Zealand matches Italy on the other side, for position and shape. Cthulhu.mythos 09:26, 18 May 2006 (UTC)
Surprising how often "everybody" can be wrong. Although it's not too far from the truth really. -- Avenue 09:46, 18 May 2006 (UTC)
I found it very odd that when I went to the antipode map page, the default location was half a block from the hospital of my birth. moink 20:07, 12 May 2006 (UTC)
I actually don't think it's that much of a coincidence that the antipodes for most land locations is in the ocean. As Rspeer points out, most of the earth's surface is water, which decreases the likelihood that the antipodes will be on land. In addition, historically, the continents tend to cluster, repeatedly coming together in one or a couple large land masses before separating again. It wasn't that long ago that there was no Atlantic Ocean, after all, that Africa and South America were both part of Gondwanaland and North American and Europe were joined in Laurasia. The continents still tend to be clustered, which certainly helps in mapmaking. This beautiful map shows that the continents are still all practically joined, and in particular this image dramatically illustrates that the Pacific Ocean nearly covers an entire hemisphere. — Knowledge Seeker 20:36, 12 May 2006 (UTC)
From an antipodean perspective, this yields some interesting results for points on land.
  • New Zealand matches to substantial areas in both Spain and Portugal, whereas Australia’s only match is tiny Bermuda
    • A lot of New Zealand, but not all of it. I'd be swimming in the Bay of Biscay. Any hardy meteorologists at the weather station on Campbell Island would be directly opposite the southwestern coast of Ireland, the Chatham Islands rotate to Montpellier in southern France, and the Antipodes Islands themselves - the nearest land to the antipodean point of London - convert to Cherbourg in Normandy. And, of course, a small part of the Northland Peninsula is antipodean to Gibraltar. FWIW, the antipodean points of the capitals of Spain and New Zealand are close to Palmerston North and Valladolid respectively. Grutness...wha? 06:49, 13 May 2006 (UTC)
      • Fair enough, I was being a litle imprecise about NZ and Spain/Portugal, and totally missed the points in France, Ireland and Gibraltar (I blame the full moon). I'm glad you clarified the antipodean points of the NZ and Spanish capitals - antipodes claims that Wellington and Madrid are opposite each other, which didn't seem quite right to me. JackofOz 07:11, 13 May 2006 (UTC)
  • Is it true that no country has antipodal points in more than 4 other countries? Brazil maps to Philippines, Indonesia, Malaysia and Brunei; Peru maps to Laos, Vietnam, Cambodia and Thailand. Can anybody better this? JackofOz 01:50, 13 May 2006 (UTC)
I certainly couldn't. China maps to Chile, Argentina, and Bolivia, but no matter how hard I tried I couldn't get it to match Uruguay or Paraguay. EWS23 | (Leave me a message!) 02:15, 13 May 2006 (UTC)
Indonesia maps to Guyana, Brazil, Colombia, Ecuador, Venezuela, French Guiana, and Suriname is tricky but can be done. —Zero Gravitas 06:07, 13 May 2006 (UTC)
Ah, excellent. I hadn't considered non-contiguous countries. I also discovered that Argentina used to map to 5 countries, if you count Hong Kong and Macau as "countries" before they were reabsorbed into China. But it's down to 3 since 1999 (China, Mongolia and Russia). JackofOz 06:31, 13 May 2006 (UTC)
For a worldwide view of what's antipodal to what, see this map. The software used to produce i