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April 7

Radio station reception

I'm not sure if this falls under technology or electronics, but if it is the latter, feel free to move this to the computing desk. One of my favorite radio stations is KFDI-FM out of Wichita, Kansas. Unfortunatly, I live in the vicinity of Salina, Kansas. This map shows the reception range of KFDI (at the range where Salina is, the reception could be classified as spotty at best). Here are the technical specifications of the station. What steps can I take to get better reception, perhaps by modifying a radio? Would a Broadcast relay station be a feasible step on the part of either the radio station or myself, considering that would allow this radio station to tap into an additional 55,000 people for it's market? In short, what ways (other than their online stream) could I attain reception of this station in Salina? Ks0stm ^(T•C•G) 01:06, 7 April 2010 (UTC)

A bigger, better, higher, directional antenna is the obvious answer. What type of antenna do you have now ? StuRat (talk) 01:03, 7 April 2010 (UTC)

I'm thinking of the type found on a vehicle so that I can get reception while driving. Ks0stm ^(T•C•G) 01:06, 7 April 2010 (UTC)

That isn't going to work, as you can't mount much of an antenna to a car. So, a rebroadcast relay station might be your only option. You could put a big antenna at your house, then rebroadcast from there, but you'd have to get the station and the FCC to agree, and good luck with that. StuRat (talk) 01:11, 7 April 2010 (UTC)

Also, that range map is rather iffy. The range is not usually completely circular like that. The two primary reasons are local geography, such as hills, and the signal being somewhat direction, when broadcast. StuRat (talk) 01:11, 7 April 2010 (UTC)

You say the range is not perfectly circular because of hills… Have you been to central Kansas? :-) —Bkell (talk) 02:48, 7 April 2010 (UTC)

I should also back up and ask why this station is so important ? Is there a particular program you just love ? Maybe there's some other way to access it. StuRat (talk) 01:13, 7 April 2010 (UTC)

The news and severe weather coverage is unparalleled, and for a severe weather fanatic like me, this makes the station very appealing. I like to monitor the station when there is severe weather to the South or southwest that may move towards Salina. Unfortunately, this is one of the times/situations it decides to offer its most spotty reception. Ks0stm ^(T•C•G) 02:05, 7 April 2010 (UTC)

Perhaps a weather radio would be in order ? StuRat (talk) 02:10, 7 April 2010 (UTC)

For news, perhaps the local NPR station, KHCD-FM, 89.5, might do. They aren't 24-hour news, but have frequent news, including in-depth stories. StuRat (talk) 02:20, 7 April 2010 (UTC)

This is probably not a practical option. But they have an option to listen on their web-site. What's the G3 covereage like in your area? You could theoretically listen on a mobile internet device like an iPhone.

(Be very carefull about monthly bandwidth caps and overage fees before trying this!) APL (talk) 04:18, 7 April 2010 (UTC)

A better antenna would be a good option. FM radio uses approximately the same frequency as VHF TV. So any good VHF (not UHF) TV antenna would also work for FM. In fact you may have a TV antenna on your roof already, and with a splitter you can get FM from it as well. There are a LOT of different kinds of antennas. I'm certain with a good antenna you could receive your station. A car would be tough, but even there you might be able to do something. For example a whip antenna tuned to exactly the frequency of your chosen station. After that any improvements (other than height) will also cause your antenna to become directional (to a greater or lesser extent depending on the antenna design). This may be tough in a car. The more directional the antenna the weaker a station you can receive, but also the harder it is to position it exactly right (plus it won't get other stations). Ariel. (talk) 05:47, 7 April 2010 (UTC)

acid rain/ fog

wouldn't fog contain more acid/impurities than rain? because its more concentrated/ has less water in it ?

Fog is not necessarily "more concentrated" than rain, it just contains smaller size droplets (which are therefore suspended in the air and don't fall to the ground). As for the amount of water, both of these form when humidity reaches saturation level, so the amount of water is the same. FWiW 24.23.197.43 (talk) 01:34, 7 April 2010 (UTC)

Fog is basically a ground-level cloud. Since rain comes from clouds - it's hard to imagine how there would be any difference in the impurity level. I suppose it's possible that rain might pick up impurities as it falls - but then we'd have to ask what the past history of cloud was. If there is a general answer, I'd guess that they would be about the same. SteveBaker (talk) 02:40, 7 April 2010 (UTC)

Acids in rain that cause acid rain usually forms dissolved compounds in the droplets such as nitric acid and carbonic acid. Impurities, or particulate matter, often forms condensation nuclei in the cloud. Since fog or cloud droplets are usually smaller than raindrops, as rain is the combination of many smaller droplets from condensation, it's possible that the minute amounts of acid or particulates in the droplets could combine and add up. However, according to acid rain, "Occasional pH readings in rain and fog water of well below 2.4 have been reported in industrialized areas" (acid fog is a red link). ~AH1^(TCU) 02:46, 7 April 2010 (UTC)

Acid fog is usually referred to as a Pea soup fog and becomes so because the fog is trapped in an Inversion layer, hence giving it time to soak up combustion products. Rain can get very polluted when caused by such instances as the bombing of Hiroshima (black rain) or rain from the ash column of an erupting volcano. The volcanic rain may well contain hydrofluoric acid, which can dissolve glass. They both should have the same load carrying capacity as the other, all things being equal. --Aspro (talk) 09:50, 7 April 2010 (UTC)

A Pea soup fog is a thick fog. Acid fog is acidic fog, it needn't be thick. Pea soupers may, however, have been acidic, but one is not necessarily the other. --Polysylabic Pseudonym (talk) 08:39, 9 April 2010 (UTC)

The term pea soup fog refers specifically to a thick fog that contains a high concentration of sulfur dioxide, usually from coal smoke. Therefore, it would have a significant acidity. In other words, any pea soup fog is by definition acidic, but not all acidic fog can be referred to as pea soup fog. 24.23.197.43 (talk) 05:07, 10 April 2010 (UTC)

Salt Level in water to corrode metal

Hi Friend,

can you help me with this?

i am constructing a recycling water system for washing vehicle.

i need to know the dissolved salt level in the water that will corrode metal.

example: maybe 2000ppm and above will corrode metal.

so i will discharge all water and replace them before reaching 2000 ppm.

please assist.

Alex Singapore —Preceding unsigned comment added by Thocy (talk • contribs) 02:24, 7 April 2010 (UTC)

Salt corrodes iron by promoting ion exchange and redox reactions between the iron and the air/water. Therefore, any amount of any salt in the water will tend to accelerate corrosion to some extent. That said, the rate of corrosion is directly related to the concentration of salt in the water -- sea water will corrode iron pretty quickly, while tap water will cause only a negligible amount of corrosion (in the short run anyway). In short, there's no hard and fast threshold above which salt will corrode iron; the main rule to remember is, the less salt the better. FWiW 24.23.197.43 (talk) 02:37, 7 April 2010 (UTC)

Water will corrode iron even without any salt. Make your pipes out of a different metal. Aluminum if you can, but it's probably hard to get pipes. Copper is probably your best bet, it resists corrosion even with seawater, and it's easy to buy. Copper pipes come (in the US) in three different thicknesses, K, L, M. K is thickest, and you way want to spend a little extra and use it instead of a thinner one. You can also use plastic, PEX is a good choice for high temperature applications, also CPVC (not regular PVC). Ariel. (talk) 05:03, 7 April 2010 (UTC)

You can also protect your iron pipes via Cathodic protection, usually by using coated iron pipes; i.e. iron coated with aluminum, magnesium, or zinc, such that the more active metal is sacrificially corroded, protecting the iron. The lede of the Cathodic protection article specifically mentions protecting iron pipes as a common usage. --Jayron32 05:08, 7 April 2010 (UTC)

But this is a vehicle washing system - isn't the problem to protect the vehicles rather than the washing equipment?!? You can certainly have the washer use plastic pipes - but if someone brings their car to be washed, the last thing they want is salty water squirted up into places where water wouldn't ordinarily go! When the roads have been de-iced with salt, I take my car to the car wash to wash the salt off. If the car wash recycles its water then after a few dozen cars have been through it, they'll be worse off than if they hadn't been washed in the first place! SteveBaker (talk) 20:14, 7 April 2010 (UTC)

“But this is a vehicle washing system - isn't the problem to protect the vehicles rather than the washing equipment?!?”. Why would someone who purports to be from Singapore be interested in protecting YOUR auto-mobile? Does the company ‘you’ work for really put the preservation of customers assets before its own? So why should Alex? --Aspro (talk) 20:54, 7 April 2010 (UTC)

The question was a very reasonable one, about a salinity limit for the makeup water system to be held to at a car wash, and I understood the limit to be for avoiding excess rust of the cars. Does anyone have referenced data to respond to it, as to industry practice? Edison (talk) 21:43, 7 April 2010 (UTC)

Here is an interesting site describing how a system which washes salt trucks (good recipe for getting salty water in the drain) did not just dump the salty water into the wewer to harm the environment, but used filtration including reverse osmosis to get the salinity of the discharged water down to 1/20 that of the tap water. Clearly a less ambitious setup could get it down to the same as the starting level in tap water. [1] under "salinity" says it is not recommended to set some safe salinity level to prevent corrosion (for reason a chemist might understand). Edison (talk) 22:30, 7 April 2010 (UTC)

Here is a company which sells equipment to reclaim water used in carwashes, including removing salt. Their technical documents might be helpful. Edison (talk) 22:35, 7 April 2010 (UTC)

physics question

Alright I've been working on this one for such a long time, could someone please help me? Two steel balls are suspended on 1.50 meter long strings of negligible mass. The first mass is released from rest from an angle of 40.0o and collides perfectly elastically with the larger mass which was originally at rest. To what maximum angle will the larger ball rise after the collision? The answer is 26.4 degrees but im wondering what to use like conservation of energy, momentum or something else. Thanks for your help. 198.188.150.134 (talk) 07:50, 7 April 2010 (UTC)

I would use conservation of momentum. But first you will also need to calculate the velocity of the first ball when it hits the second (acceleration due to gravity). The by using conservation of momentum you know the velocity of the second ball, and then you'll need to calculate how high it will rise due to that velocity (inverse of before), and then a little trig to see what angle that makes. I'm pretty sure that doesn't make any difference that it moves in a curve, rather than straight down, so use the angles to calculate height, but otherwise ignore it. Ariel. (talk) 07:59, 7 April 2010 (UTC)

why not use conservation of energy? m1*g*r*(1-cos(40deg))=m2*g*r*(1-cos( ? deg)) gravitational potential energy 157.193.175.207 (talk) 09:03, 7 April 2010 (UTC)

edit : this is the 'maximum' height in the sense that it is the height reached if the first ball transfers all of its energy to the second ball. You probably need 2 equations (energy and momentum conservation) to figure out how the energy gets redistributed over the balls. 157.193.175.207 (talk) 09:06, 7 April 2010 (UTC)

Yes, you need to use both conservation of momentum and conservation of energy. Unless the two balls have the same mass (which we can infer they do not) then the first ball is not stationary after the collision and so does not transfer all of its energy to the second ball. Gandalf61 (talk) 12:23, 7 April 2010 (UTC)

If you want us to do numeric calcs, we'll need to know the relative masses of the two balls. StuRat (talk) 10:15, 7 April 2010 (UTC)

...or we can work backwards and infer that the first (swinging) ball has half the mass of the second (stationary) ball. Gandalf61 (talk) 12:23, 7 April 2010 (UTC)

@157 and Gandalf: you do need to use both conservation of energy and momentum, but you don't necessarily need to do it with two equations. A helpful simplification is that in an elastic collision, from the center of mass reference frame, the balls appear to be each traveling at the same speed before and after the collision. Buddy431 (talk) 13:49, 7 April 2010 (UTC)

So let's see here: I get that the first ball drops 0.35 m, and so is traveling at a speed of 2.62 m/s before the collision. The second ball reaches a height of 0.16 m, and so was traveling at a speed of 1.75 m/s after the collision. The 2nd ball was initially at rest, so we see that the center of mass must be moving at half that speed, or 0.88 m/s, during the collision. An elementary center of mass calculation shows that the second ball has twice the mass of the first. Buddy431 (talk) 13:49, 7 April 2010 (UTC)

Changes in cooking oil

I have put this on the science desk because it seems to be a science based problem. I have been cooking in sunflower oil in a small electric fryer. The fryer and the basket is now soiled with a kind of adherent waxy/rubbery substance which is clearly altered oil. It is on the areas of the fryer which are open to the air, that is, it is not below the level of the oil, just the lid, basket and handle. What type of substance is this? How can I clean the fryer because it seems to be impervious to detergents and caustic dish-washing products. Caesar's Daddy (talk) 09:27, 7 April 2010 (UTC)

It is the oil that has under gone Polymerization. Is the vessel stainless steel , aluminium or glass etc.,--Aspro (talk) 09:55, 7 April 2010 (UTC)

The main part is Teflonned aluminium, others are plastic. Caesar's Daddy (talk) 10:06, 7 April 2010 (UTC)

I was going to suggest steel wool, but it sounds rather delicate, and would be scratched by anything that would clean it, so I think you're just going to have to live with it. StuRat (talk) 10:10, 7 April 2010 (UTC)

Try very hot water with laundry detergent and a stiff toothbrush. As the construction involves aluminium avoid caustic soda, which would otherwise have been my suggestion. DuncanHill (talk) 10:18, 7 April 2010 (UTC)

Teflonned aluminium! Oh dear. Personally, I would never fry in Teflon cookware do to the toxic by products caused by heat -so throw it away.[http://www.ewg.org/reports/toxicteflon] Also, the cooking oil industry has spent billions persuading both the public and the medical industry that saturated fats are bad, despite the fact that the healthy liver produces them. For frying in future, and to avoid this rubbery gummy stuff, use hard fats like coconut, palm, or if your not kosher, ghee or lard. They are the best. These also have the advantage of being able to cook at higher temperatures without burning. Also, change fat frequently, to avoid a build up of acrylamide. If the teflon coating is in good condition then you could risk applying some soda crystals which is less caustic. The liquid version that comes in a squirt bottle is easiest to use as it is just the right consistency. Coat liberally and leave over-night. Next morning remove as much of the softened rubbery gum as possible. Apply some more soda and leave again. Main ingredient required is ‘patience.’ The Teflon coating should protect the aluminium beneath. --Aspro (talk) 10:57, 7 April 2010 (UTC)

Toxic products due to high temperature teflon is not so true. By the time you reach a high enough temperature to release anything toxic, oil would have released massive amounts of smoke, or even caught fire. In other words, you never get the teflon that hot. Ariel. (talk) 18:12, 7 April 2010 (UTC)

The OP seems to be talking about a deep fat frier. I don't think you can practically deep fat fry things in ghee or lard (I've never used coconut or palm oil). You would also be using enormous amounts of the stuff. I use a small amount of ghee when making curries, but I would never soak my food in the stuff, it would be a heart attack on a plate. While saturated fats are an acceptable part of your diet, they are only acceptable in small amounts. --Tango (talk) 14:38, 7 April 2010 (UTC)

Fish and chip shops across the North of England use beef dripping to fry their food. The taste is far better (in many people's opinion, including mine) than frying stuff in oil. The dripping heats to a higher temperature, which instantly seals the food, and reduces absorption of the fat by the food: in which case, it should even be healthier than frying in oil. [2] Don't whatever you do use palm oil: you will render orangutans homeless! [3] Olive oil is not really suited to deep frying, being too heavy. I think you need to clean your fryer much more often than you have been! --TammyMoet (talk) 14:58, 7 April 2010 (UTC)

If you are genuinely concerned about orangutans it's surely better to use sustainable palm oil rather then try and halt development in SEA completely because you've already destroyed a significant part of your forests so wanna feel good by forcing people to preserve stuff for you at no cost. Particularly since if you don't encourage the growth of the industry, what's likely to happen is it will be sold to places like China where there's far less incentive to do anything properly and there being no similar prescription on say soyabean oil which is more inefficient to produce and could come from the Amazon (of course a big part of it goes for cattle so perhaps you don't have to worry about the oil) or say the plenty of inefficiently produced oils in the developed world (but as I said it's okay, we cut down the natural forest there a long time ago so no need to worry) P.S. Just to be clear, I'm not saying you shouldn't consider the environmental effects of your decisions but that I strongly dislike the simplistic thinking that goes into things like 'don't buy palm oil, you will render orangutans homeless'. Things are alot more complex then fit in a Greenpeace slogan unfortunately and it's all to convient to care about environmental problems in other countries where your decisions are not going to have a big effect on you or the people you know and your country and then not worry about the ones far closer to home which will affect such things. Sadly simplistic thinking leads to things like thinking of jatropha as a wonder crop, we all know how that's turned out so far [4]... Nil Einne (talk) 23:08, 7 April 2010 (UTC)

Thanks for those responses - very helpful. I think we are going to be finding an alternative to sunflower oil. We used to use olive oil which did not polymerise to such an extent but was more costly - ah well, you get what you pay for (usually). Thanks again. Caesar's Daddy (talk) 13:59, 7 April 2010 (UTC)

Try corn oil. See Smoke point for a nice list. Note that Sunflower oil has two entries in the list, and also that the smoke point is not everything, the particular type of oil matters too. I don't know which type is better/worse for frying though. If you check the articles for the particular oils you'll see a wide variety in what specific kinds of oils they are made of. Ariel. (talk) 18:12, 7 April 2010 (UTC)

I disagree with the promotion of saturated fat usage by Aspro, and suggest you read Saturated fat as to the increased health risks associated with high consumption of these fats. Edison (talk) 14:26, 7 April 2010 (UTC)

Agreed. StuRat (talk) 14:33, 7 April 2010 (UTC)

Thanks chaps, I'm not as daft as I look. [5] Caesar's Daddy (talk) 15:48, 7 April 2010 (UTC)

The questioner was not asking about a balanced diet of fats. So I can’t be accused of promoting saturated fats per se. Also, I stated clearly that the cooking oil industry has spent billions promoting their products. These sales and marketing factoids are based on theories without substantial scientific proof that diets high in saturated fats cause CVD (co-morbid smoking rates did much confuse the results and so call them into question still further). Nor have the pharmaceutical industry proven that lowing blood cholesterol reduces death in ‘real populations’, nor do they attempt to explain why population with diets very high saturated fats (like the Inuits) have enjoyed low levels of CVD (until they adopted western diets). These awkward facts are often mention in medical journals such as the BMJ. There is much nonsense written and repeated about fats and oils. Prof. Udo Erasmus has probably done the most thorough systematic review of fats and oils, if you would like to discover more. Here is his bit on frying. [6]. His book also has a complete bibliography of the papers referred to so you can download them and read them for yourself. Finally, the best fish (with omega 3) and chips are deep fried in lard and always have been. Once a week on a Friday, they can form part of a good balanced diet. --Aspro (talk) 15:57, 7 April 2010 (UTC)

And why would the those promoting low saturated fat oils have more money to spend than those promoting their high saturated fat products ? StuRat (talk) 18:19, 7 April 2010 (UTC)

I would that answer along these lines: First: don’t think of it as low verses high; that’s a sales and marketing position. People used to consume a variety of different fatty acids.

Second: Lard, beef dripping, mutton tallow, coconut oil were all established fat rendering industries. So was lubricating oils from rape seed. When plant breeders found that they could produce vegetable oils that were cheaper than traditional fats and that they could be modified to be used as pseudo substitutes, the breeders and oil processors were able to convince their governments to trumpet their products (and to give them attractive tax incentives to spend money on sales and marketing, applied research etc.). This, their government were/are willing to do, as it increases growth in exports. Also, by possessing these oils so that they had longer self life their profits increased further. These companies (like others in a competitive market place) used these profits to increase their market share. People new the price of lard but did not realize they where paying over the odds for vegetable oil. That’s how.--Aspro (talk) 18:21, 7 April 2010 (UTC)

Does "paying over the odds for vegetable oil" mean "getting subsidized discounts on vegetable oil" ? StuRat (talk) 18:56, 7 April 2010 (UTC)

?

I have forgotten the name of the logical fallacy that you're introducing but I get the drift of you question.

A landowner once waxed lyrical to me once about how much European Union subsidy he was getting per hectare of rape. So yes, I suppose he was able to sell it for less, than he would, if he did not receive the subsidy. However, a few years ago when I was doing some cost analysis for a friend who was about to open a restaurant, the traditional fats cost a lot more. Pig farmers in Europe/coconut farmers etc., work to very tight margins. They don’t get the same sort of preferential treatment as other fatty acid producers. So, I would ‘say’ (and I emphasis this because I don't have hard figures to hand ) that the public has paid the full cost of traditional fats AND at the same time, paid over the odds for vegetable oils for which the producer has also received government subsidies. So whilst Joe Public has been able to buy ‘cheaper’ units of food, the industry that produced it, and the retail trade that sold it, was able to extract more of a percent profit per unit.--Aspro (talk) 19:57, 7 April 2010 (UTC)

I think you're reading way too much into my Q. I just don't know what the expression "paying over the odds" means. StuRat (talk) 00:46, 8 April 2010 (UTC)

In that case: pay over the odds--Aspro (talk) 18:51, 8 April 2010 (UTC)

So it just means to overpay ? StuRat (talk) 00:09, 9 April 2010 (UTC)

Isn't that what I just said?--Aspro (talk) 23:11, 10 April 2010 (UTC)

Actually, you gave me a link that said "Phrase not found in the Dictionary and Encyclopedia", but which did contain other links that eventually led me to that conclusion. StuRat (talk) 03:59, 11 April 2010 (UTC)

I've looked into cooking oils for deep frying and there are many factors to consider. For example, how often do you deep fry? How do you keep the oil? Unless you're Bill Gates, cost is an important factor. For example you may think it worth spending say double for oil which lasts longer. But would it be better to use the cheaper oil but change twice as often? Nil Einne (talk) 23:12, 7 April 2010 (UTC)

Hey guys, enough already. I was asking about cleaning the fryer. Please step outside my question if you have other issues ;-)) Caesar's Daddy (talk) 18:57, 8 April 2010 (UTC)

Renal agenesis

Are there any simple symptoms to tell if you were born with one kidney (unilateral renal agenesis)? My father was born with one kidney, but he didn't find out until he was 31.--十八 09:29, 7 April 2010 (UTC)

This is something you'd need to see a medical practitioner for, as the easiest way to diagnose such a problem is by a scan. Regards, --—Cyclonenim | Chat  09:49, 7 April 2010 (UTC)

Have a look at this article. In particular, "URA [unilateral renal agenesis] is an asymptomatic condition usually discovered during routine prenatal ultrasono­graphy. Before the advent of prenatal ultra­sound, the diagnosis of URA was usually made incidentally when radiographic studies were performed for other reasons." The short answer is: no. Axl ¤ [Talk] 21:54, 7 April 2010 (UTC)

Advanced search engine for sound

Do you think there will be a possibility to search media by their envelope? Instrumental and vocal music can share similar envelop for example regardless their frequency spectrum and sampling rate, and so if a sample of music were submitted to the search engine such that I will search and compare other similar music.--Email4mobile (talk) 12:09, 7 April 2010 (UTC)

It certainly sounds possible. I don't think it exists yet (at least, I've never heard of it). Ways of searching for similar images are just starting to be invented (you can find them online, but they aren't very good yet). I expect finding similar sounds would be a similar problem. Come back in a few years. --Tango (talk) 12:48, 7 April 2010 (UTC)

A few years ago there was a service where you could call a phone number and (sorry the details are fuzzy) either hum a piece or hold the phone up to a radio and it would tell you what piece of music it was. No idea how limited a pool of choices ("stuff played on the radio" is a pretty small set!) or how well it worked. DMacks (talk) 12:57, 7 April 2010 (UTC)

I recall having seen (and more or less successfully tested!) an internet search engine where you could enter a rhythm pattern in plain text. The engine produced a list of popular songs matching the pattern. It was pretty nifty. This was about 10 years ago. DVdm (talk) 13:02, 7 April 2010 (UTC)

I remember one where you entered symbols to indicate whether the next note was higher or lower in pitch than the one before, and it worked out the tune from just that information. 86.21.204.137 (talk) 13:24, 7 April 2010 (UTC)

Yes! That's the one I had in mind. My memory got a bit rusty. Do you know whether it's still around? DVdm (talk) 13:38, 7 April 2010 (UTC)

Google is my friend:

• Songtapper for rhythmic patterns does good job.
• Click and sing or hum not tested - no mike.

DVdm (talk) 13:58, 7 April 2010 (UTC)

Oh hey, we have a Multimedia search page on the topic, and a list of articles about specific sites too. DMacks (talk) 13:06, 7 April 2010 (UTC)

The ear is something of a frequency analyzer, and responds to the frequencies present or the sound spectrogram rsther than to the shape of the envelope, which is more sensitive to phase than is the ear. Certainly it should be possible to search for a matching sound sample with a given envelope. But the envelope shape is not that critical to how we perceive a sound. Two performances of the same vocal or instrumental passage might sound the same to us, but look quite different on an oscilloscope. Edison (talk) 14:22, 7 April 2010 (UTC)

Well, I think Edison is right. I've just recorded a vocal song on one channel and its instrumental music on the other. I realized that envelops were almost different. I wonder how then our ear can recognize it? Is it just a frequency response or is their other kind of processing? --Email4mobile (talk) 15:20, 7 April 2010 (UTC)

Shazam can, when given an obscure cover of a well-known song, tell what the song is, but not who's covering it. CS Miller (talk) 19:33, 7 April 2010 (UTC)

germinating

In this image of a conker germinating, is the one on the right the root part or the leaf part? Thank you for your help 82.44.54.207 (talk) 13:12, 7 April 2010 (UTC)

Yes, it is a conker sprouting. The white visible part is the root, or radicle which you can see is trying to go downwards as it is positively geotropic. The leaf shoot will appear in a day or so and start to grow upwards. You need to get it into the ground or a pot if you intend to grow it. Caesar's Daddy (talk) 14:08, 7 April 2010 (UTC)

But how do you know it hasn't been turned over for the pic ? StuRat (talk) 14:15, 7 April 2010 (UTC)

Because I am 60+ years, I have seen more sprouting conkers than I care to count and this is a perfectly normal, regular-looking photo of a sprouting conker. If the conker had been placed with the sprout going upwards I would have concluded that it was either a badly posed conker or possibly a mutant conker with reverse tropism attraction - it happens. The main fault in my answer was not noticing it was a stock photo and then suggesting the OP plant it, doh! Caesar's Daddy (talk) 15:45, 7 April 2010 (UTC)

Then you didn't conclude it's the root because "you can see is trying to go downwards", but for other reasons. StuRat (talk) 17:24, 7 April 2010 (UTC)

Correct, but then I didn't claim that was the main ID feature, I just noted it as an aside. My main conclision was based on the fact that the first white pointy thing that comes out of the conker is the root!! Caesar's Daddy (talk) 21:59, 7 April 2010 (UTC)

Yes. The shoot that goes sky ward is not pointy but is a leaf bud that almost immediately divides into two (I seem to remember) as soon as the root hairs appear. --Aspro (talk) 16:48, 7 April 2010 (UTC)

Experiment at Geneva

Can any body explain in a simple language about the experiment going at Geneva ??? —Preceding unsigned comment added by 117.197.251.56 (talk) 15:03, 7 April 2010 (UTC)

I assume you talk about the Large Hadron Collider or LHC? Simply said, they accelerate charged Hadrons, i.e. protons or other atomic nuclei around a large vacuum tunnel to very high speeds, and then let them collide with each other. In the collision, a part of the kinetic energy of the particles is converted into new and sometimes interesting particles, according to E=mc² (E in this case is the kinetic energy of the particles, m the mass of the newly created particles - all somewhat simplified). Physicists have certain models about which particles should be created, and they check if these can be observed after a collision, confirming our current theories of matter. More interesting is the case that they cannot be observed, in which case they try to figure out what happened instead and how to explain it. --Stephan Schulz (talk) 15:16, 7 April 2010 (UTC)

(edit conflict with above) Are you referring to the Large Hadron Collider at CERN? Basically, they are taking subatomic particles (protons, in this case) and smashing them together at very high speeds. When particles collide with so much energy, lots of weird stuff happens (you create types of particles that normally aren't seen), and scientists try to examine the weird stuff that happens to figure out more about how the universe works. Experiments like this have been going on a long time (about 50 years), but the Large Hadron Collider is a lot bigger than anything else used before, and so can get particles moving at much higher speeds than any other particle accelerators. Because the LHC is bigger, and the collisions have more energy, scientists are hoping to see new types of weird stuff that they haven't ever observed (the most interesting thing would be the Higgs boson). Buddy431 (talk) 15:17, 7 April 2010 (UTC)

A Simple English article is at simple:Large Hadron Collider. The collider smashes protons together at very high speeds. The protons are destroyed and other things are made. Scientists measure what is made. AlmostReadytoFly (talk) 15:19, 7 April 2010 (UTC)

Unfortunately, that article is not simple English, but written at Kindergarten level and "simply wrong"... --Stephan Schulz (talk) 16:08, 7 April 2010 (UTC)

"Simple" does seem to mean "kindergarten-level" over there (technically, that's closer to a third to fifth grade reading level, but I get your meaning). It doesn't seem entirely wrong though. Technically, a proton *is* a hydrogen atom with its electrons "stolen". I'm sure physicists would slap their heads if someone tried to speak with them using the terminology in the article, but for children in early grade school or those with a weak grasp of English, it's close enough. What do you think is wrong with it? —ShadowRanger ^(talk|stalk) 18:40, 7 April 2010 (UTC)

See the edit history - I already fixed two whoopers. The black hole story is at least suspicious - how do we know that cosmic rays do not create black holes all the time? I thought the idea of Simple is to explain concepts using simple language, not to oversimplify the concepts. That seems to be very hard to separate, though. --Stephan Schulz (talk) 19:50, 7 April 2010 (UTC)

Yeah, that paragraph at the end was a joke. I'm actually okay with the original wording for your other edit though; "break" is pretty close to what they're trying to accomplish. The wording on black holes could use improvement, but given that we're talking about what are, from the point of view of the simple Wikipedia, two different things ("real" black holes vs. "transient" or "fake" black holes), it's understandable. Maybe something like: "The LHC is doing the same thing that cosmic rays do when they hit the Earth. Either no black holes are being created by the cosmic rays, or the black holes created are very tiny and would go away on their own. In either case, the LHC would be safe." ?—ShadowRanger ^(talk|stalk) 20:40, 7 April 2010 (UTC)

Side-note: It's really damn hard to write a description of particle physics without using any complex words. I'm amazed I managed to do it without going to three syllables. —ShadowRanger ^(talk|stalk) 20:40, 7 April 2010 (UTC)

Is this why there is (as yet) no Particle Physics for Dummies book available, I wonder? :) --Kurt Shaped Box (talk) 20:50, 7 April 2010 (UTC)

You joke, but there are Dummies books for absurdly complex subjects in Physics, including Quantum Physics for Dummies and String Theory for Dummies (which includes a section on particle physics). —ShadowRanger ^(talk|stalk) 20:56, 7 April 2010 (UTC)

Sweet. I was joking before - but yes, I might actually have to take a look at those... :) --Kurt Shaped Box (talk) 21:29, 7 April 2010 (UTC)

(Re. SRRIT): No, the "breaking" is a definitive no-no. If they "broke" the original particles, how could they ever make bigger (well, heavier) products from them? You need to get the energy into this somehow. --Stephan Schulz (talk) 21:23, 7 April 2010 (UTC)

Electric drill rating

I am confused by the fact that wired drills are rated in volts. Battery drills in watts. (Or the other way round.) What rating battery drill do I need to get solid power? I have had a 14w for some time, and it just does not have enough power, nor battery life. Help, please.Froggie34 (talk) 15:04, 7 April 2010 (UTC)

Watts describe the power the drill will consume/deliver (for electric motors, the difference is not very large). A wired drill should have a power rating of 500W or more - good ones often have more than one kW. Volts denote the voltage of the drill. In principle, voltage and power are independent (you can get more power by increasing either voltage or current, i.e. amps). In practice, wired drills will almost always have more power than battery drills, because it is not economically feasible to build very compact batteries that can deliver 500 W for any amount of time (and having them deliver this for a long time is not even technically feasible). But if you look carefully, both wired and battery-driven drills should have ratings of power (W). --Stephan Schulz (talk) 15:24, 7 April 2010 (UTC)

The way you said “solid power” makes me wonder if you mean Torque as well. I can read power tool spec. sheets but I still seek out a competent trades person, to see what he uses for the sort of use I am intending to do. You can’t really suss that out from a spec. sheet. Professionals will sometimes welcome a genuine request for their expertise in their choice in power tools. I have found it cheaper in the long run to accept what they say as being right. They use them day in day out and know all the cons and pros, and which offer the best value for money.--Aspro (talk) 16:33, 7 April 2010 (UTC)

Wired ones are rated in watts, and cordless ones in volts - and it's totally a gimmick. The volts makes no difference at all, they could make the same power drill with half the volts and double the current (amps). Do you need the drill for drilling or for driving screws? If for screws what you actually care about is torque. Or actually torque plus speed under load. There is no one good way for rating a drill. For wired, watts is a reasonable measure, but you will also want to check the toque - which is often hard to find. The unloaded speed is usually printed on it. And more or less, the higher the watts for the same speed means more torque. When you say "not enough power" what do you mean? Doesn't last long enough (watt hours)? Can't turn tight screws (torque)? Doesn't spin fast enough? Ariel. (talk) 18:25, 7 April 2010 (UTC)

I used to repair professional and consumer power tools at a tool shop for a few years and I would definitely recommend not to choose a tool based on what it claims its watts or volts are, those numbers are usually more misleading then useful. A cheap less efficient tool will usually actually have a higher wattage rating then a better and more efficient one. It's a very similar story with speakers, you can get nasty cheap 150w speakers for a few bucks but they will be total rubbish compared to some good quality 80w speakers. If you are looking for a good tool don't expect to pay peanuts for it, if you buy the cheapest one you'll get the crappiest one. I agree with the poster above to try to find a trades person and see what they use on the job, even if you spend a bit more to start with, you're much more likely to get a tool that will serve you for a long time. Also, you CAN get very good wireless tools these days but you will pay a lot more for it. Unless you actually have a specific need for a wireless tool, more then just pure "convenience", I still recommend wired tools. More reliable, last longer (batteries and even chargers typically go obsolete every few years), and much better price / performance ratio. Vespine (talk) 22:30, 7 April 2010 (UTC)

Thank you all very much. I need a drill to deliver effective power, so I suppose I mean torque. Anyway I am greatly helped.Froggie34 (talk) 08:31, 8 April 2010 (UTC)

gravitation

If gravitation is like accelerated frame of reference(as stated in general relativity) why don't the accelerated mass move away from the body creating the gravitational field? —Preceding unsigned comment added by 113.199.137.150 (talk) 17:04, 7 April 2010 (UTC)

Because the acceleration is in the oposite direction of what you are thinking, towards the body generating the field. Dauto (talk) 18:12, 7 April 2010 (UTC)

Organ donation

I'm trying to remember the term given to organ donations (such as kidneys) where you donate to a random person whom you don't know? I'm not considering it, just haven't a mind blank. Regards, --—Cyclonenim | Chat  17:44, 7 April 2010 (UTC)

I think it's typically called "nondirected donation" [7], but our organ donation article calls it "undirected donation". Paul (Stansifer) 17:50, 7 April 2010 (UTC)

Searching "nondirected donation" gave me the term I was looking for: altruistic donation :) thanks Regards, --—Cyclonenim | Chat  22:37, 7 April 2010 (UTC)

Time Travel

In a recent TV interview (available on youtube [here]), the physicist Brian Cox stated that "you can travel into the future at any speed you want relitive to other people". Can anyone help to explain what he means by this? This statement got me a bit confused! thanks! 80.43.182.69 (talk) 18:47, 7 April 2010 (UTC)

Well he's on Twitter at @ProfBrianCox. Why don't you tweet him and see what he says? --TammyMoet (talk) 18:57, 7 April 2010 (UTC)

Your "[here]" link seems to be missing. I suspect he's talking about time dilation, where time slows down for people going close to the speed of light, but continues at the same rate for everyone else. So, by adjusting your speed, you could also adjust how fast you go forward in time relative to others. However, you can't go back in time this way. See Time dilation and space flight. StuRat (talk) 19:04, 7 April 2010 (UTC)

I think it would have been less sensationalist to say that "in principle you can make time pass more quickly for yourself by building a spaceship that can fly close to the speed of light". However, there is no way to build such a thing with any technology we have. Also, this idea of "speeding up time" is not what most people think of when they think of time travel to the future - they imagine that you climb into this box the size of a telephone booth - type in some date in the future and press the Big Red Button and SHAZAAM!!! there you are in The World of Tomorrow! But that's not what Brian Cox is talking about. This would be more like: you climb into a gigantic rocketship - fire up the engines and S-L-O-W-L-Y (over a period of a year or two, get up somewhere close to light speed. Then, as you zoom along, you see events in the rest of the universe start to speed up. Everything inside your spaceship seems normal enough - but outside, there is some seriously weird stuff happening. When you are close to the time you want to be, you turn the spaceship around and start slowing down again (which takes another year or two) - and NOW you are "in the future". Not exactly "SHAZAAM!". But it's theoretically possible thanks to Einsteins' relativity. For the "SHAZAAM!" kind of time travel, you'd need to get into your spaceship and go into 'suspended animation' while the spaceship speeds up and slows down again...but we don't know how to do suspended animation either - so it's still not going to happen anytime soon. Of course all of this only works in the forwards direction. Once you're in the future, you are very definitely stuck there - and there is no similar way to travel into the past. SteveBaker (talk) 19:57, 7 April 2010 (UTC)

I'd say we're far closer to suspended animation than near light-speed travel. We can freeze and revive some simple animals, now we just need to figure how to stop ice crystal formation in our cells, and we could do the same. StuRat (talk) 00:39, 8 April 2010 (UTC)

Yep. There are prospects of taking genes from various fish and amphibians that can survive being frozen solid by having natural antifreeze in their cells. However, that kind of genetic engineering of humans has enough ethical concerns to push it quite a way out into the future. SteveBaker (talk) 02:20, 8 April 2010 (UTC)

For less drastic time dilation, you could always try living your whole life on top of the highest mountain you could find (ideally close to the equator). Granted, it wouldn't even add a second to your life (I don't care to do the math, but I've seen figures online that claim you'd "gain" a second every four millenia or so). Since the Earth bulges at the equator, and the mountain adds more height, your speed (relative to anyone else on the planet at a lower altitude) would be greater. Like I said, not practical, but an amusing concept. —ShadowRanger ^(talk|stalk) 20:28, 7 April 2010 (UTC)

Steve, that's not how it works. Moving away from Earth you would see Earth events redshifted, i.e., going slower. Moving towards Earth you would see them blueshifted, i.e., going faster. It does add up, overall, to more elapsed time on Earth, but not obviously. The right way to think about time dilation is in terms of the overall length of the paths through spacetime. If you have two curves, one of which is a straight line and the other of which wiggles around but starts and ends at the same place, the wiggly curve is longer (because a straight line is the shortest distance between two points). You can say that the wiggly line is longer "because of the wiggling" (i.e., the acceleration). But it doesn't really make sense to say that the wiggly line is "longer per unit length", whatever that would mean, in the places where it's at a large angle to the straight line—and that's basically what people are saying when they say that "time goes slower when you're moving quickly". -- BenRG (talk) 00:01, 8 April 2010 (UTC)

Yeah - I know - I was over-simplifying for the sake of making a comprehensible explanation. At least I didn't simplify to the degree Cox did! SteveBaker (talk) 02:18, 8 April 2010 (UTC)

Sorry, this is the link i meant to post [8], he makes the aforementioned statement about 2 minutes in, but fails to expand on it. Thanks! —Preceding unsigned comment added by 80.43.182.69 (talk) 22:24, 7 April 2010 (UTC)

Steve, just have to pull you up on your cryogenic stuff. ONE animal (an antarctic nematode) has been shown to survive INTRAcellular freezing. Fish don't freeze, they avoid freezing, which is pretty easy when you're in water - you just have to hope it doesn't freeze all the way to the bottom. I've only heard of freeze tolerant insects - no higher animals I can think off, and they avoid intracellular freezing, only coping with extracellular ice formation. Aaadddaaammm (talk) 13:15, 8 April 2010 (UTC)

Does Harrison Ford count as a "higher animal"? 24.23.197.43 (talk) 06:30, 10 April 2010 (UTC)

by INTRAcellular freezing do you mean freezing in all areas but inside the cell? maybe you meant intercelluar freezing? anyways, there are plenty of animals that freeze solid and live normally after thawing out. There are several insects that do and usually whenever an insect does anything you can bet there'll be several more that do and we just haven't discovered them yet. I don't know if you count animal eggs to be animals (I do) and there are many that survive freezing.--FUNKAMATIC ~talk 03:58, 14 April 2010 (UTC)

Photographs

I take bad pictures. I know people that take very good pictures. Is there any technology in the foreseeable future that can render subjects more accurately? Imagine Reason (talk) 20:53, 7 April 2010 (UTC)

Well, autofocusing DSLRs already exist and can take very good pictures. True DSLRs cost a lot of money, but they're the best choice for advanced amateurs and many (if not most) professionals. Autofocus is a crutch (you can usually get better pictures if you learn to tweak your focus manually), but it's a good crutch for beginners. Combined with photo editing software like Adobe Lightroom, which can fix up flaws in lighting/exposure levels as well as tuning contrast and hue, a sufficiently determined amateur can produce effectively professional quality photos. Doesn't mean their pictures will be "art", but they can at least not look like cheap Polaroids. —ShadowRanger ^(talk|stalk) 21:06, 7 April 2010 (UTC)

Weird. I posted after Sperm Whale, but it didn't give me an edit conflict or anything, just shoved it in above your post. —ShadowRanger ^(talk|stalk) 21:07, 7 April 2010 (UTC)

What sort of camera do you have? A point-and-shoot or a bridge digital is less likely to take good quality photos than a DSLR. Also, what is wrong with the photos? If the composition is boring, then you have to learn to take better photos. If the images are noisy and poor quality, then it is the camera's fault. Hope this helps, --The High Fin Sperm Whale 21:04, 7 April 2010 (UTC)

A trend toward faster ISO settings (more sensitive sensors) will allow faster shutter speeds in low light than now, and greater depth of field in low light situations without needing a large lens opening. Automatically deployed electronic flash reduces subjects being in a shadow or under exposed in general. More powerful flash in future cameras might allow more use of bounce flash (bouncing it off the ceiling rather than direct flash) for a more natural appearance, and for subjects farther away. Some new cameras purport to be able to detect and focus on faces, and to take the picture when the person is smiling. Some cameras purport to automatically reduce motion blur. These features should spread to cheaper cameras and work better in the future. The display on the back of the camera lets you easily see how you have composed the photo (and make sure your thumb is not in front of the lens. Automatic rapid sequence of exposures reduces the need to precisely time the photo to catch the action. Larger memories in future cameras will allow more bracketing of exposure and more rapid fire sequencing, without filling memory. A camera klutz will not automatically get better pictures with a fancier DSLR than with an automatic point and shoot. I hope that future cameras are more rugged (not destroyed when dropped or splashed). If the future camera has what amounts to a self-stored tripod to keep it from moving around, (like a means of securely sticking it to a wall or table) picture sharpness would be improved due to less motion blur, and it would be easy to automatically take pictures of the same subject at high and low exposures, to combine correctly exposed parts of the scene in the shadow, and parts outside in sunlight, with exposures near enough the same time that subjects moving around is not a problem. It would also make it easier for the photographer to be in the picture, especially if a remote trigger and remote viewing screen were included. Motion-triggered photography would make surveillance or photos of animals visiting the back yard easier. Avoiding a loud-clacking mirror in the typical DSLR would make it easier to photograph things without calling attention. Edison (talk) 21:35, 7 April 2010 (UTC)

Hi Edson, what software is there around to combine images taken at different exposures to get a good result? Graeme Bartlett (talk) 22:01, 7 April 2010 (UTC)

Read High dynamic range imaging and HDR tonemapping & exposure for some suggestions. There are LOTS of software packages out there that relate to High Dynamic Range (HDR) imaging and photography. SteveBaker (talk) 02:13, 8 April 2010 (UTC)

I'm sorry I wasn't clear. I meant that I don't come out as nice-looking as I do in real life, while some other people look better than they are in person. Imagine Reason (talk) 03:26, 8 April 2010 (UTC)

OK, some hints then:

1) Learn which is your "best side" (it may be straight on, rather than either profile).

2) Before picture taking, sneak off to the bathroom to comb your hair, wipe off any sweat, tuck in the shirt, etc.

3) If you are overweight, hide the fat parts behind others, and wear dark colors and vertical stripes. Make sure pics are taken from above to hide double chins. If seated, put something on your lap you hide your belly, like a pet, kid, or pillow. StuRat (talk) 03:59, 8 April 2010 (UTC)

Just to note the 'vertical stripes' thing was on QI the other night stating that research has shown that vertical stripes don't make people appear more thin. 194.221.133.226 (talk) 08:32, 8 April 2010 (UTC)

... and be aware that most people perceive that they themselves look worse in photographs than others perceive them and worse than they perceive others. In this case, perception may not be reality. Is it because we seldom see ourselves in "real life"? Dbfirs 05:56, 8 April 2010 (UTC)

We usually see ourselves in mirrors, i.e. side-reversed. Humans are not quite symmetric, and the difference is significant. So on photos you don't look like you would expect to. --Stephan Schulz (talk) 08:40, 8 April 2010 (UTC)

This is true - and it's sometimes recommended that you judge photos and portraits of yourself by looking at them in a mirror. SteveBaker (talk) 19:19, 8 April 2010 (UTC)

Photogenic is the word that you are looking for, as in "I am not photogenic". At the end of that article is a link to How To Be Photogenic, which might answer your question. Mitch Ames (talk) 06:53, 8 April 2010 (UTC)

Also...good photographers don't necessarily accurately represent reality as it was (well maybe good forensic photographers) - but artistically they make use of tools and techniques to get the image to look how they want. Photographing people is no different. Taking photos of groups for instance regularly means that people have to bunch-up a lot closer than they would comfortable feel. By being much closer together the image looks better, more composed, perhaps even more 'natural' - yet the situation that created it is (for many) a bit worrying. The other factor that is huuuugely important is lighting - good lighting and bad lighting make for huge variance in whether something (or someone) looks good in an image or bad. Remember our eyes perceive the world somewhat differently to how a camera does (since it just captures anything from 1/50th of a second to 1/40,000 of a second typically). 194.221.133.226 (talk) 08:37, 8 April 2010 (UTC)

Camera-wise, the best thing you can do, is use a suitable focal length for the shot. This article by Ken Rockwell explains things clearly. [9]--Aspro (talk) 09:59, 8 April 2010 (UTC)

(I moved the following answer by Edison to the correct section - it didn't seem to say much about Time Travel!) SteveBaker (talk) 02:33, 9 April 2010 (UTC)

Since you clarified that your concern is how you look in photos rather than how to take photos, many celebrities on magazine covers have had their images extensively retouched, by Photoshop or otherwise. It is practically universal. Skintone is evened, nose hairs removed, wrinkles smoothed, broken veins in the nose removed, blemishes removed, banjo eyes fixed, suntan added, teeth whitened, extra chin removed, bald spot covered. This is one way technology can make your photo look better. Some people freeze when a camera is aimed at them and someone says "SMILE!" or squint, or fix their mouth in a phony rictus of a "smile which does not go all the way to the eyes." If a camera is aimed at you and takes a photo silently every little bit you might forget you were being photographed and then, at some point the instant might come where you have a pleasant and natural expression, and bingo, you have a better picture than usual. The key here would be good natural light and a memory which can capture a whole bunch of automatically taken photos. Edison (talk) 19:32, 8 April 2010 (UTC)

The benefits of this "natural pose" may be somewhat reduced, if it includes a finger placed up the nose. StuRat (talk) 12:26, 9 April 2010 (UTC)

I think there is something called "blind deconvolution" which can look at a photo, measure the blur due to it being out of focus or due to camera shake, and then automatically undo the blur to produce sharper images. There is some free software somewhere on the internet that does this. I've never got around to trying it out yet. See for example http://www.quarktet.com/BlindDecon.html

There is also High dynamic range imaging which produces more satisfying images. In practical terms I suggest when using a camera, try to reduce camera shake by using a fast shutter speed (if you have a choice), putting your elbows against your chest for extra stability, and holding your breath while gently pressing the 'trigger'. Best to have the sun behind you, and do not be afraid to get up close to people. Think about the shapes the image will make. There is also some software available that automatically improves people's skin. Professional photo portraits are usually done from a distance with a telephoto lens - I suppose getting up close makes your nose look bigger etc - and in modern times with lots of diffuse lighting, particularly fill-in lighting from below to remove wrinkles eyebags and the toothbrush-moustache shadow from your nose. Lighting is very important. 78.147.131.74 (talk) 20:26, 9 April 2010 (UTC)

Titan arum

Just wondering, but the article on the Titan arum (Amorphophallus titanum) says it is a flowering plant. Does anyone have a picture of it flowering? Also, is this a picture of the titan right after it blooms? Thanks in advance, --The High Fin Sperm Whale 21:00, 7 April 2010 (UTC)

Yes, that's the inflorescence. It's not technically the flower, as the actual flowers are at the bottom of the central column (spadix), hidden by the spathe. -- 140.142.20.229 (talk) 21:08, 7 April 2010 (UTC)

Here [10] is a diagram that indicates, with labels, the component parts of the inflorescence. Richard Avery (talk) 21:52, 7 April 2010 (UTC)

Destruction of chlorate explosives

Can chlorate explosives be destroyed, e.g. by a bomb squad, by reacting them with hydrochloric acid?

KClO₃ + 6 HCl → KCl + 3 H₂O + 3 Cl₂ —Preceding unsigned comment added by Cheminterest (talk • contribs) 21:41, 7 April 2010 (UTC)

Such a reaction would surely release a lot of heat, which is bad around bombs. Additionally, Cl₂ is itself a pretty strong oxidizing agent, and would likely react with whatever the fuel in the bomb was. So yes, I suppose they could be "destroyed" that way, but the destruction might take place as a detonation, which sort of defeats the purpose. Buddy431 (talk) 00:18, 8 April 2010 (UTC)

Bomb squads sometimes detonate the bomb in place (after evacuating all civilians from the danger zone, of course) if there's no other way to get rid of it without endangering themselves and others. FWiW 24.23.197.43 (talk) 06:03, 8 April 2010 (UTC)

Yeah, but if you're trying to blow up a bomb, there's got to be better ways than pouring a nasty chemical on it, creating an even nastier chemical, and seeing what happens. I admit that I have no idea how bomb squads do dispose of bombs, but at first read, this doesn't seem to be a very good way of doing it. Buddy431 (talk) 14:21, 8 April 2010 (UTC)

They use a small satchel charge made of C4 explosive, just like in The Hurt Locker. 24.23.197.43 (talk) 00:16, 9 April 2010 (UTC)

population control

Communist China limited families to one child as national policy. Why now then does Communist China object to pornography which is proven to reduce the number of incidences of copulation both within a marriage and without thus automatically reducing the the number of children a male will produce? 71.100.3.207 (talk) 23:48, 7 April 2010 (UTC)

Perhaps the government should hand out blow-up dolls ? :-) StuRat (talk) 01:14, 8 April 2010 (UTC)

"proven"? Can you cite sources for any of these very doubtful claims of yours? Comet Tuttle (talk) 01:17, 8 April 2010 (UTC)

No, because if you are using porn then I do not want to interrupt that because it leaves more unattended ladies for me. 71.100.3.207 (talk) 04:14, 8 April 2010 (UTC)

It's because population control isn't the only thing that their government is concerned about. They would probably argue that any marginal benefits of porn in terms of limiting population growth was outweighed by the moral decline of society that it brings. I don't think I agree with either of those conclusions - but this is about their ideas, not mine! SteveBaker (talk) 02:01, 8 April 2010 (UTC)

Why does the Catholic Church insist on dictating other people's sex lives while turning away advice for their own? It's about power and fidelity to the organization. 67.243.7.245 (talk) 03:24, 8 April 2010 (UTC)

Whoa, that was uninformed. By writing "other people's" you imply the Catholic Church is a person. I doubt you can cite reference to when the Catholic Church insisted to it. "It's" in your second sentence is referring to the Catholic Church's sex life. I doubt you meant that ,and regardless if you did, it makes your statement quite funny. In taking your probable meaning, the Catholic Church and the government of The People's Republic of China don't make commandments and laws (respectively) just to illicit loyalty and gain more power. The commandments and laws are a means to an end. That end (I believe) being the modification of the masses' behavior. In the Catholic Church's case I assume it's to better the lives of mankind, and in China's government it may be less selfless. You may not actually care, but did you know the rate of sexual abuse in the Catholic Church is no higher than other churches? Check this out.--FUNKAMATIC ~talk 04:18, 14 April 2010 (UTC)

The Chinese government is very concerned with what it considers to be moral decay. It also gets a lot of political mileage from regulating pornography—it is (if I recall) something like the top reason they cite for needing to regulate their internet communications, and resonates very well as a justification within China. (Even outside of China, there are a lot of people who think regulating internet pornography would be a good idea, not realizing that the kinds of regulations you put in place for that are easily transferred to other realms of communication.) Communists of the Soviet/Chinese variety were always pretty uptight about sexual and social things despite their association with the "left" in the rest of the world. --Mr.98 (talk) 12:29, 8 April 2010 (UTC)

Pornography is seen as a social vice in China. ~AH1^(TCU) 03:35, 10 April 2010 (UTC)

April 8

Miners "surviving" by eating sawdust and bark

At a page bearing "Copyright © 2010 The Associated Press" we find the article "Rescuers race to reach 32 trapped in China mine" which is one of a number of places i've seen/heard wordings like "The 115 miners survived for eight days underground by eating sawdust, tree bark, paper and even coal." A few have said ambiguous things like "staved off hunger", but i think it's widely known that unlike cattle, humans lack both the enzymes to digest cellulose, and the ability to harbor (as cattle do) the bacteria that do have the enzymes. I assume that putting some non-digestible bulk into your digestive tract may do your spirits some good, and possibly provide some respite from the sensation of "gnawing" hunger (incipient starvation), but is it possible that there's any benefit in terms of providing calories? My bet is that even if there's a tiny amount of sugar-bearing sap in sawdust, or of digestible substances in bark, the energy required to synthesize and excrete HCl and other digestive fluids is going to outweigh the energy extractable from the sawdust or bark. (This is not even weighing in the hazard of poisoning by bark, which in many cases includes substances that kill insects that try to eat it, or make at least make them go away, and are likely to be toxic to humans, as with most manufactured insecticides.)
So what's the chance that eating sawdust or bark (from the timber shoring up the ceilings, i assume) is a way to delay starvation? (For extra credit, is there anything in paper -- sizing? -- that makes it a better choice? And what about coal dust, which includes substances that can't even be burned?)
--Jerzy•t 00:55, 8 April 2010 (UTC)

Poor Haitians Resort to Eating Dirt. I couldn't understand this either. I'm afraid the article doesn't explain it, either. Bus stop (talk) 01:00, 8 April 2010 (UTC)

I agree with you that it wouldn't do any more than the placebo effect. One thing that starving people might have handy that could do some good is leather, if they could manage to boil out the tanning chemicals. StuRat (talk) 01:08, 8 April 2010 (UTC)

We have an article on Geophagy but I think we need an article on Edible clay. Bus stop (talk) 01:16, 8 April 2010 (UTC)

Experts claim habit of eating dirt may be beneficial for some. Bus stop (talk) 01:19, 8 April 2010 (UTC)

But humans can easily live for much longer than 8 days without food, so it's not like the minors needed calories. My guess is that they were just filling their bellies to reduce the sensation of hunger. Buddy431 (talk) 01:28, 8 April 2010 (UTC)

According to this survivalist website (http://www.survivaltopics.com/survival/edible-pine-bark/), many forms of tree bark (at least when freshly collected and cooked) are edible and nutritious. Dragons flight (talk) 01:41, 8 April 2010 (UTC)

No, eating wood does not do anything to delay starvation. To produce energy, the body needs organic chemicals like proteins and Sugars. Wood is almost 100% cellulose, which is basically a huge chain of the sugar Glucose. However, humans cannot digest cellulose. In fact, no animal can. Any animals that do (e.g. Termites) have to use bacteria in their stomachs to break it down into simpler sugars. --The High Fin Sperm Whale 01:52, 8 April 2010 (UTC)

If bacteria don't count, then animals can't digest very much of anything, on their own. StuRat (talk) 02:12, 8 April 2010 (UTC)

I gave my source. Here's two more discussing the potential to eat bark for nutrition [11][12]. Our own article on bark says: "The bark of some trees is edible...", and gives the example of a kind of bread made from tree bark. We eat lots of plants, like carrots and lettuce, that give us few calories per volume but aren't totally worthless. I suspect bark is in the same category. Not much useful nutrition but not zero either. If you believe there is nothing at all that is digestible in bark, then I suggest you give your source(s). Dragons flight (talk) 02:33, 8 April 2010 (UTC)

The issue isn't having no nutritional value, it's having fewer calories than it would take to digest. There may also be other "foods" which fall into this category. StuRat (talk) 02:39, 8 April 2010 (UTC)

But that's still assuming a conclusion without proof. I listed sources that say eating bark (at least under some conditions) can be beneficial. If you contend that it is a net negative, then what is your evidence / source? Dragons flight (talk) 04:28, 8 April 2010 (UTC)

At least one kind of bark can be beneficial; see Cinnamon. Nyttend (talk) 01:17, 9 April 2010 (UTC)

I don't think you get any calories from it, though, unless you mix it with sugar. StuRat (talk) 12:20, 9 April 2010 (UTC)

If you don't have to exert yourself, you can live for a very long time without food. There have been hunger-strikers who have lived for 70 days without food - so 8 days is very survivable. Now - if you don't have water, you're in trouble very quickly - but that evidently wasn't a problem in a flooded mine! So it's pretty clear that the bark did nothing than make their stomachs more comfortable - and since morale and the will to survive are very important in such situations, it could be said that eating it helped them - but not nutritionally. SteveBaker (talk) 02:09, 8 April 2010 (UTC)

This is how that works out for the minimal BMR of 1650 per day. A person with 32 lbs of body fat to spare to pay his BMR bill of 1650 calories per day has about 130,634 calories to spend. That's only about 80 days if his or her body only needed calories to burn. Most references, however, say two weeks at most. 71.100.3.207 (talk) 06:49, 8 April 2010 (UTC)

No - two weeks is far too little. Check out Hunger strike - and in particular, the various Irish republicans. Of the two major strikes, one involved nine people - and was called off when two of them died after 94 days(!), and in another case, around 8000 prisoners stopped eating - one died after 35 days and another after 37 days when the strike was called off. That's a pretty solid statistical sample. Out of 8,000 people - all but two survived for 37 days. We can imagine that those two deaths were of people who for one reason or another were more susceptable to problems - so the great majority would probably have survived much longer had the not returned to eating again. The fact that of 9 people, only two died after 94 days says that this is much more likely to be the ultimate limit. But in a more recent hunger strike, ten men died after between 46 and 73 days. Of course all of these people were lying still in bed for most of that time and had plenty of water (and in some cases, salt) - so their calorie requirements were minimal...but I think two weeks is a very low limit - there are no cases in Hunger strike of people dying after as little as 14 days...and even 80 days is by no means an upper limit. SteveBaker (talk) 19:15, 8 April 2010 (UTC)

I would expect there to be a fantastic difference in the length of time one can survive without food between individuals. Perhaps the 2 weeks would be for someone with anorexia, whereas Senor Lardo who is 450 lbs of bigmac fed blubber could likely surpass 3 months (assuming he does not have a stroke or something). So there should be a chart that determines how long you can go without food based on your weight and body fat%, rather then just using the median results of humanity as a whole. Googlemeister (talk) 20:35, 8 April 2010 (UTC)

Indeed - but the sample of 8,000 hunger strikers must represent a wide swath of people. Not a perfect statistical sample - but since every single one of those people survived for 34 days, it would have to be someone with some rather serious other condition to prevent them from surviving a month. Maybe the two weeks includes pregnant women or small children or something - but a moderately healthy, normal adult can go a month without eating - no problem. So (dragging this thread back on-topic) a bunch of good, strong miners would certainly have survived more than 8 days without resorting to eating bark. SteveBaker (talk) 02:26, 9 April 2010 (UTC)

Perhaps the author (or the miners) were merely referring to psychological survival since overeating due to attacks of the hunger monster (dare not I call it a God as some ancient Egyptian or other religious sect may have) is what presents the greatest difficulty to modern day dieters who are not allowed to stop eating altogether to build complete resistance to the hunger monster's attack. 71.100.3.207 (talk) 19:34, 9 April 2010 (UTC)

A mouthful of soil would probably contain close to a million species of bacteria. Maybe some of the bacteria have nutritional value? ~AH1^(TCU) 03:33, 10 April 2010 (UTC)

"Tree bark" refers to two very different sets of tissues - the "outer bark", which is largely cork, and which would have very little nutritional value, and the "inner bark", which consists of living tissue, and includes the phloem, the tissue which transports sugars. Think maple syrup. Granted, the concentration of sugars aren't going to be all that high most of the year. But depending on the plant, you could probably get some sustenance by chewing bark. Guettarda (talk) 05:09, 12 April 2010 (UTC)

A bit off OP topic, but could'nt you easily survive the mine collapse by not eating, keeping warm, getting water and air... like going into hibernation - Link: http://inhumanexperiment.blogspot.com/2010/03/curious-case-of-human-hibernation.html

Are there diets that cause a person to not defecate?

I have heard that there are diets that will cause a person not to generate any feces, but all my google searches (e.g. "how do i stop pooping") are turning up articles about how to stop a dog from pooping on the rug. Any help please? Is there such a diet? 207.237.228.236 (talk) 01:07, 8 April 2010 (UTC)

Just fasting. No food in, no food out, then you die. Or you could get all your nutrition intravenously, which would work for a while, but eventually you'd get an infection or a nutritional imbalance and die. StuRat (talk) 01:10, 8 April 2010 (UTC)

• The references you hear to feeding tubes (which deliver food to the stomach without need for swallowing) reflect the fact that caloric requirements alone inherantly limit how long life can be sustained by intravenous feeding. It may still be the case that the limit of what is feasible in the way of intestinal surgery is set by whether the patient will starve on IVs before their traumatized intestinal tract can resume its job of absorb nutrients (first priority: calories).
  It works like this: too many calories per cc, and your blood is too thick to flow thru the capillaries, or maybe first the osmotic pressure destroys blood cells and the hemoglobin plugs up the nephrons in your kidneys. But the IV can't flow any faster than your kidneys can extract water from your bloodstream unless it's pumped in, driving up your blood pressure and destroying your kidneys (for most people, IIRC, before a stroke or random hemorrhage kills you). So they give you all the salinated sugar-water that flows in, and your body burns fat (leading, IIRC, to ketoacidosis which is pretty bad for reasons i can't remember) to make up the difference, and when you run out of surplus fat, it starts burning muscle and, at some point, indispensable fat. (Can you survive to the point where it starts cannibalizing the fatty myelin that many nerves need to function properly? Dunno.) At any rate, its not that hard to get dead by living on an IV.
  --Jerzy•t 05:33, 8 April 2010 (UTC)
  

• You'd think there'd be solutions to those probs, like blood thinners and multiple IV sites. And, if the kidneys aren't fast enough to keep up, how about dialysis ? StuRat (talk) 13:36, 8 April 2010 (UTC)

Presumably if you eat "foods" that totally dissolve in water you'd have a shot at not having any solid waste. I'd imagine one could prolong life with nothing but Gatorade and sugar water, but I don't think it makes for a healthy permanent lifestyle. Dragons flight (talk) 01:48, 8 April 2010 (UTC)

You are thinking of a low residue diet. 68.116.194.175 (talk) 01:55, 8 April 2010 (UTC)

Low residue, yes - but zero residue, no. SteveBaker (talk) 02:10, 8 April 2010 (UTC)

• Hmm, not zero bcz your gut bugs keep multiplying as long as you get adequate nutrition via your stomach?
  --Jerzy•t 05:33, 8 April 2010 (UTC)
  

US Army C rations were specifically designed to provide a fairly balanced diet while minimizing the amount of fecal matter produced. Not zero-residue of course, but pretty low-residue by most people's standards. FWiW 24.23.197.43 (talk) 06:06, 8 April 2010 (UTC)

Are you thinking of “Total" Parenteral Nutrition where someone has had their gut removed?[13]--Aspro (talk) 11:19, 8 April 2010 (UTC)

I don't see how you could eat Army rations (or anything else) if you had your gut removed. 24.23.197.43 (talk) 00:20, 9 April 2010 (UTC)

I assume that Aspro tabbed once too much, making it look like they were replying to you, when they were really replying to the original Q. StuRat (talk) 00:58, 9 April 2010 (UTC)

Help with a physics question

This is a link to a past pre-tertiary (grade 12) Physics exam: [14]
Read Question 9.
The answers to the exam are found here: [15]
Why do the positive and negative charges repel, as it would appear on the diagram on the answers document? I thought opposite charges attract.
--Alphador (talk) 06:12, 8 April 2010 (UTC)

The positive and negative ions are not repelling one another. They are moving in different directions because of the magnetic field. See Faraday's law of induction for a comprehensive explanation. There is a section devoted to magnetic flow meters. Dolphin51 (talk) 06:24, 8 April 2010 (UTC)

Is the ability of scopolamine to suspend free will an urban legend?

I read an article about it on the Internet but it (the article) seemed to have a tongue-in-cheek feel to it. 20.137.18.50 (talk) 12:28, 8 April 2010 (UTC)

This is covered, at some length, in the scopolamine article. -- Finlay McWalter • Talk 12:37, 8 April 2010 (UTC)

Seems like it would be a much better interrogation tool than waterboarding if it really works. 20.137.18.50 (talk) 15:15, 8 April 2010 (UTC)

Agreed with you on this one. From what I know (and don't quote me on this), scopolamine was used as early as World War 2 by both the Nazis and the Allies (and possibly even earlier). It's still occasionally used today, but these days the truth serum of choice is usually sodium pentothal. Now, the biggest limitation of both these drugs (and of truth serums in general) is that, because they work by partially suppressing the conscious mind, they only give reliable results when you're interrogating someone for specific information that they're hiding -- for example, if you know that your captive is planning a terrorist attack, and you want to know when and where it will take place. If, on the other hand, you want information that requires your captive to do some conscious thinking, you're better off using other means, like blackmail or something of the sort. 24.23.197.43 (talk) 00:32, 9 April 2010 (UTC)

Life project

Is there a distributed program (like the SETI program) that starts with the fundamental constituents of life responsible for the synthesis of inorganic and organic compounds or proteins, fats and carbohydrates to see what things might be created in cyberspace that could be useful or stable in the real world? 71.100.3.207 (talk) 14:21, 8 April 2010 (UTC)

Folding@home and Rosetta@home are the first things that occur to me. They may not exactly hit your target, but they're close. --Tagishsimon (talk) 14:58, 8 April 2010 (UTC)

Wikipedia's "team" at Folding@Home is currently ranked around 2,500 out of 175,000 teams: [16] 75.41.110.200 (talk) 15:17, 8 April 2010 (UTC)

Wow that's very poor, my team is ranked 971 and we have lesss membres than wikipedia. Keep it running.--92.251.159.172 (talk) 16:57, 8 April 2010 (UTC)

No! It's good! It means that Wikipedians are busily using their computers for editing this humungous dictionary instead of vegging out on the sofa while their computer runs the Folding@home screen saver! SteveBaker (talk) 18:36, 8 April 2010 (UTC)

I run it in the backround all constantly, it doesn't affect my performance much when playing graphics intensive games either.--00:42, 9 April 2010 (UTC) —Preceding unsigned comment added by 92.251.166.223 (talk)

Is there a way to join the Wikipedia team? I wouldn't mind getting in on the action. 130.126.130.146 (talk) 19:28, 8 April 2010 (UTC)

Just enter the team number for Wikipedia in the client setup. Team number is 42223. —ShadowRanger ^(talk|stalk) 20:10, 8 April 2010 (UTC)

Are there any distributed programs that are used to create translations for written texts in an extinct language? Similar to brute forcing an encryption? Googlemeister (talk) 20:29, 8 April 2010 (UTC)

I'm fairly sure that would be impossible for all practical purposes. Words won't match up one to one, grammar will differ, etc. A different alphabet (which is basically what you're doing with encryption, though it's a really complex alphabet for anything more powerful than substitution ciphers) is the least of your worries. And if the language is based on pictograms, you're basically completely screwed without huge amounts of material to work from. There is a reason we needed the Rosetta Stone to decipher Egyptian hieroglyphics, and a reason that the U.S. used Navajo code talkers during WW2. Even in less difficult cases, it would still amount to writing an AI program, not a code breaking algorithm. —ShadowRanger ^(talk|stalk) 20:50, 8 April 2010 (UTC)

SUV fuel tank

What is a typical volume for a current model year SUV gas tank? Ballpark number is all I need. ike9898 (talk) 14:49, 8 April 2010 (UTC)

20-30 gallons ? Less than that for compact SUVs, and more than that for full sized. StuRat (talk) 14:59, 8 April 2010 (UTC)

20-25 gallons, depending on the size of the SUV. Ford's lineup, for instance, ranges from 16 gal (the Escape) to 33 gal (the Expedition) with the 22 gal Explorer in the middle. Honda's Element has 17 gal, the Pilot 19 gal. — Lomn 14:59, 8 April 2010 (UTC)

On the high end, the 3/4 ton 2010 Chevy Suburban has a 39 gallon tank. StuRat (talk) 15:50, 8 April 2010 (UTC)

Be aware that the gallon comes in different versions - your tankage may differ, depending on location. 87.81.230.195 (talk) 16:36, 8 April 2010 (UTC)

I would expect that all these values are in US liquid gallon (≈ 3.8 L), since the others are for dry measure and for use in the UK and Canada (where I suspect liters are used, by now). StuRat (talk) 16:47, 8 April 2010 (UTC)

Thank you all. ike9898 (talk) 16:58, 8 April 2010 (UTC)

What is the technical name for the sensation that there is someone behind you?

...and does Wikipedia have an article about this phenomenon? In a related question, is there a specific term for the aversion (not perhaps on the level of a phobia, but similar) one might have for having people behind you? Thanks, Lithoderm 15:14, 8 April 2010 (UTC)

Paranoia would include the feeling that you are being watched. StuRat (talk) 16:07, 8 April 2010 (UTC)

It depends on whether you mean an hallucination, such as that that can be induced by the God helmet or spatial acoustic awareness caused by sensing changes to the echo in a room, which can happen when someone walks up behind you but many people don't normally notice. The latter is I suppose, a form of echo location. Some people feel unsettled when they first experience an anechoic chamber due to the sudden absence of this phenomena. If it feels 'eerie' then you might be reacting to sub-audial Infrasound.-.--Aspro (talk) 16:59, 8 April 2010 (UTC)

Honey-bee prefered row crops in the U. S.

I am trying to think of what row crops honey-bees may like best. Do they tend to shy away from plants that have tassels like corn or millet? Anyone have any Ideas? —Preceding unsigned comment added by 160.36.38.126 (talk) 15:40, 8 April 2010 (UTC)

Most grains with tassels (such as corn and wheat), and even most grasses, are wind-pollinated. They don't rely on insects like bees to do any of the pollination, and as such do not usually provide nectar as an enticement to attract bees. (Bees will visit corn tassels to collect pollen, though.) Bees prefer to feed on plants with visible flowers - indeed most scientists believe (showy) flowers evolved specifically to attract insect pollinators. -- 140.142.20.229 (talk) 16:46, 8 April 2010 (UTC)

Bees pollinated crops list: [17] Many of them are planted rows including vegetables and oilseeds, even apples and almonds (they're planted in rows, too!) Others aren't like alfalfa and clover. Occasionally oilseeds are broadcast planted. Rmhermen (talk) 18:22, 8 April 2010 (UTC)

They also seem to like roses. FWiW 24.23.197.43 (talk) 00:39, 9 April 2010 (UTC)

Gastroenteritis

Not a question for medical advice. Exactly how does the virus/bacteria cause stomach cramping and bloating in gastroenteritis? I did read this but I was looking for an explanation why or how this causes the stomach muscles spasms and bloating. --Reticuli88 (talk) 15:44, 8 April 2010 (UTC)

Abdominal bloating is generally caused by the accumulation of gasses in the gut. Generally, these gases are the result of waste products produced by Gut flora; that is all of the bacteria that normally live in your digestive tract eat what is passing through your gut, and they expel gas as a waste product. In a healthy person, most of the gas production occurs at the end of the colon and in small amounts, so it is easily expelled by farting. If you have gastroenteritis, you have some sort of bacterial infection higher up in the disgestive tract, and THOSE bacteria are producing lots of gas in a place where it is not easily expelled, because it has to pass through a lot more of your digestive tract. The normal involuntary muscle movements that pass food along through your upper intestines (see Peristalsis) is inadequate to move this gas to your bum faster than it is produced, so the gas builds up and becomes uncomfortable. Additionally, the pressure on the walls of your intestine generated by this gas, besides being uncomfortable in itself, can cause the muscles lining the digestive tract to cramp or spasm (think of a charley horse in your intestines), which itself can be very uncomfortable. --Jayron32 18:54, 8 April 2010 (UTC)

Thanks Jayron. Is your explanation what describes a bacterial gastroenteritis? What happens when the gastroenteritis is from a viral infection? --Reticuli88 (talk) 19:09, 8 April 2010 (UTC)

I believe in the viral case, the intestinal lining inflames, causing similar effects. Opportunistic infections (or even overgrowth of "good" bacteria) would lead to other symptoms (such as excess gas production). —ShadowRanger ^(talk|stalk) 20:45, 8 April 2010 (UTC)

Armour vs railguns?

Approximately what thickness of steel would be needed to stop a shell about the same size as that fired by a 5 inch naval gun travelling at 6,000 m/s? What about a projectile comparable to a 16 inch naval gun shell travelling at the same speed? What materials (tungsten? DU?) would be more effective than steel at stopping these projectiles, and approximately what thickness of those would be required?--92.251.159.172 (talk) 16:53, 8 April 2010 (UTC)

There are many more variables than just speed. Is this a solid shell, high explosive, shaped charge, DU? Can the shell be guided? Can we use ablative or reactive armor? Rmhermen (talk) 18:25, 8 April 2010 (UTC)

What is the range that the shell is fired from, that will make a difference. You have a ton of drag at mach 17, maybe even enough to trash the projectile before it arrives at the target. Googlemeister (talk) 18:59, 8 April 2010 (UTC)

I got the impression that the speed was the instantaneous speed at point of impact, not the launch speed. If he meant launch speed, then range becomes one of the most important aspects, for exactly the reasons you gave, and a definitive answer is going to become more of an equation. —ShadowRanger ^(talk|stalk) 19:03, 8 April 2010 (UTC)

Hi 92.251.159.172. If your a loyal and humble citizen of the wonderfully, quaint and picturesque Duchy of Grand Fenwick, then chill out... you're a landlocked principality and battleships will not be able to navigate that far up river. --Aspro (talk) 19:26, 8 April 2010 (UTC)

Replying to Rmhermen: the armor-piercing properties of HE and shaped charge shells depend on the size and shape of the explosive charge and do not vary with the projectile speed (which also means that there's no particular advantage in firing them from a railgun as opposed to, say, a conventional anti-tank cannon -- what, no article?). The most effective round for a railgun would prob'ly be a depleted uranium shell (high density, excellent hardness, and good high-temperature properties). 24.23.197.43 (talk) 00:50, 9 April 2010 (UTC)

Another complicating factor is the angle of the impact. If the round arrives at a perfect right angle to the armor, it can penetrate through far more armor than if it impacts at an angle. If you look at the design of tanks, they go to a lot of trouble to make sloping surfaces everywhere they can. Since the angle of impact also depends on the range (because of the parabolic trajectory), this adds another complication to the range-versus-penetration curve. SteveBaker (talk) 02:05, 9 April 2010 (UTC)

Need help identifying a Prunus species

Can anyone identify this species of Prunus? I'd like to upload some more photos of the same tree, but I'd rather have a correct ID first. I'm thinking it's probably Prunus americana? –Juliancolton | ^Talk 16:57, 8 April 2010 (UTC)

Looks like Prunus americana to me. Does it have thorns? How do the flowers smell? P. americana flowers smell rather nasty. You may want to try asking at the Dave's Garden plant identification forum [18], they are very good there. Winston365 (talk) 01:58, 9 April 2010 (UTC)

Posted at that forum (thanks!) and I'll look more closely at the tree tomorrow. Thanks for the help. –Juliancolton | ^Talk 03:37, 9 April 2010 (UTC)

shewees

are sheewees issued as military kit to female soldiers/sailors/airwomen? —Preceding unsigned comment added by 86.128.31.228 (talk) 18:07, 8 April 2010 (UTC)

No. SteveBaker (talk) 18:29, 8 April 2010 (UTC)

Given the difficulty in finding a place to store it safely and the arguable benefit of being able to pee standing up instead of squatting, I can't imagine why they would. Hell, with practice women can pee standing up (even if some find it mildly gross); if the squatting is really an issue it would be simpler to learn to pee standing. —ShadowRanger ^(talk|stalk) 18:55, 8 April 2010 (UTC)

The space shuttle has a similar device:NASA: Waste Collection System. Everything that NATO uses has a NATO Number. I don't currently have access to the data base but I can imagine extended duration missions where such a device would prove to be a great convenience. --Aspro (talk) 19:42, 8 April 2010 (UTC)

The space shuttle needs it because of the whole "no gravity" thing (male astronauts use it too). Astronauts dislike floating around in their own pee; can't imagine why. ;-) Soldiers of either gender are perfectly capable of peeing in the field without special equipment. —ShadowRanger ^(talk|stalk) 20:08, 8 April 2010 (UTC)

Quote:"female soldiers/sailors/airwomen"? (my emphasis) Wikipedians, (whose knowledge about female aviators doesn't stretch beyond what they know about their own great aunts antics during their time as test pilots for the local broom factory), may not appreciate the practical problems women face. Oh come on! Haven't you ever been on a an adventure holiday with the opposite sex and far, far away from a 'Holiday Inn' with showers and all those other things..? Err... well..? Evaluation of urine collection equipment in female aviators. AND DON'T FORGET TO LOWER THE SEAT, AFTER YOU HAVE READ THIS!--Aspro (talk) 20:51, 8 April 2010 (UTC)

Again, that's for a case where there is a problem for both genders. Men can't pee effectively while flying a fighter jet either. If you read the link, they are simply redesigning an existing urine collection device for male pilots to accommodate female pilots as well. It uses a funnel, but it is by no means indicating standard issue sheewees. —ShadowRanger ^(talk|stalk) 20:57, 8 April 2010 (UTC)

True story: I used to work for a company that made flight simulators - the fancy kind with big hydraulic motion bases. We built a military simulator for either a big transport aircraft or a large helicopter (I forget which) that had a "crewman relief tube" mounted in the side of the cockpit for the pilots to pee into during long missions. In the real aircraft it had a lever that opened an external valve to suck the pee outside the plane. The interior of the simulator had to be very realistic - and we'd buy up a lot of real aircraft parts to kit them out properly - and we had an actual crewman relief tube to put into the simulator - but the guys who were building the cockpit didn't know what the thing was for so nobody bothered to make it go anywhere. To make it fit into the cramped space of the simulator cabin, they cut off the outside end with the valve and blocked it up with a metal plate. Needless to say, the simulation was evidently good enough that at one pilot got "lost in the moment" and forgot he wasn't in the real aircraft, and with a certain inevitability the tube rapidly filled up - and squirted pee back all over his trousers - and all over the floor of the simulator! Subsequent versions of the simulator replaced the authentic tube with a section of appropriately painted broom handle! SteveBaker (talk) 01:51, 9 April 2010 (UTC)

One of the few times a urinal peed on a person, methinks. StuRat (talk) 18:35, 9 April 2010 (UTC)

is the following experiment valid?

Is it valid to test whether prayer helps plants with the following experiment: 1. control of doing nothing versus test of NutraGro plus prayer that the plant will grow at only a normal level despite the NutraGro. In all other respects (except for the addition of the NutraGro and the lack of prayer and of prayer respectively) the groups will be exactly the same, and blinded until the end.

If there is no statistically significant difference between the groups despite of the prayer, then the conclusion is that prayer must have worked. If there is a statistically signifant difference, then the prayer must have failed, as the prayer was obviously not granted.

Thanks for any tips you might have on this methodology. Note: please don't suggest the obvious idea of praying that a positive do happen, rather than fail to happen, as the God to whom these prayers are addressed is not of that personality, but very badly tempered and disposed to nothing except causing ruin and failure when so pressed. Thank you. 82.113.106.90 (talk) 19:40, 8 April 2010 (UTC)

The experiment as stated sounds flawed. Consider instead: 1)Control group: no prayer, no fertilizer. 2)Prayer, no fertilizer. 3) Fertilizer, no prayer. 4)Fertilizer and prayer. Each Group should be several individual pots, rather than one big tray with a bunch of plants, to spread random effects of over/underwatering and avoid a seeming significant effect of the experimental variable which is just due to watering, how near the window, etc. This way each plant is actually independent of the other plants, and you have the degrees of freedom you think you do in the statistical analysis. Then do Analysis of variance with one of the statistical packages. I would expect a main effect of fertilizer and no significant effect of prayer. If the fertilizer alone had no benefit, then the experiment as stated would false conclude that the negative prayer worked. Now consider the statistical power of the experiment: failure to find a significant effect of prayer might just mean you had too few plants (fallacy of accepting the null hypothesis. Edison (talk) 19:53, 8 April 2010 (UTC)

(edit conflict) I am completely confused by what experiment you wish to do? Are you praying for the unfertilized plant to grow? Or are you fertilizing all of your plants and then praying that they all grow exactly the same rate? Praying for nothing to happen, and then having nothing happen, is hardly an experimental proof of prayer. It would work far better if you only had one variable, so what I would do is to plant a series of plants under the exact same conditions (level of watering, fertilizer, sunlight, etc) and then you pray that some of the plants grow, while you don't pay any attention to the others... However, you should be aware that even the Christian bible says "Don't put God to the test", i.e. God knows your motivation for praying, and He is inclined to respond in the negative to any prayer that is intended solely for the purpose of testing Him, so if you are taking a Christian understanding of prayer, a negative result would not disprove the power of prayer. Furthermore, there's the axiom "God answers all prayers. Its just that sometimes His answer is "no"..." So yes, you could structure a proper scientific experiment to test the power of prayer, however there are aspects of prayer which, as explained in the scriptures, would render fairly useless the results of any such experiment. Prayer is a matter of faith, and such matters are usually outside of the realm of falsifiability, thus are outside of the realm of science to test. --Jayron32 19:57, 8 April 2010 (UTC)

As I explained, the prayer is not directed to the God of the bible. Rather, to a God who just meddles and causes things to fail, which He (supposedly) reliably does at the least prodding. This God doesn't care if you test Him. He just wants something to wreck, and is happy to be asked to do so. In this case, I will be asking Him to have the NutraGro fizzle and fail to work. 82.113.106.90 (talk) 20:20, 8 April 2010 (UTC)

SO you invented your own God, gave him some personality traits arbitrarily, and you are testing to see if praying to your God, who you created and whose characteristics you decided he should have, using rules you made up will confirm or deny if he responds to prayers in the manner in which you have decided he should? What is the point in that? --Jayron32 20:29, 8 April 2010 (UTC)

It's no worse than testing against any other god. Aside from a more extensive history and a larger group of followers, it's all basically the same thing. If he said he was praying to Loki or Coyote or any other trickster deity and expected similar results, would that somehow be better? —ShadowRanger ^(talk|stalk) 20:41, 8 April 2010 (UTC)

Well, it is, because all religious belief systems involve some form of Divine revelation whereby the Supreme Being or Beings makes themselves known to the Faithful. There is a difference between a valid religious belief system, and making stuff up in your free time. Ultimately, however, the premise of the experiment is flawed not because of the god that the experimentor chooses to pray too (be it Yahweh, or Loki, or the Invisible Pink Unicorn), its that matters of faith are not falsifiable. If some idea is not falsifiable (that is, it could never be proven false) then it isn't an experimentable idea. --Jayron32 21:00, 8 April 2010 (UTC)

Who's to say his particular deity doesn't make itself known by making you consider its existence in a moment of boredom? Perhaps that is the source of the revelation. Not to mention that revelation isn't a prerequisite for religion, particularly in animist religions where you don't need to have a tree inform you that it houses a supernatural spirit. Beyond that, if his deity is in fact as predictable as he believes, then it would be falsifiable. Just because most religions make vague and unverifiable claims doesn't mean his religion has to as well. It just means that it's not very likely his religion will survive very long. —ShadowRanger ^(talk|stalk) 21:16, 8 April 2010 (UTC)

For the record, I have personally invoked a very similar deity to the OP's, specifically the "Demons of Irony" and/or "The Universe's Non-stop Hate Parade". I was just joking around. Maybe I missed a divine revelation? ;-) —ShadowRanger ^(talk|stalk) 21:19, 8 April 2010 (UTC)

There are two variables different between your control group and your test group (the prayer and the NutraGro), so it's a bad experiment. If you want to test the effect of prayer, then you need to either give NutraGro to both groups or neither, otherwise you are also testing the effect of NutraGro and you won't be able to separate the two effects. --Tango (talk) 20:15, 8 April 2010 (UTC)

The problem with your proposal is that I don't know what "fails to work" means, since you don't have a control that doesn't get the NutraGro. How about the control is the NutraGro and no prayer for it to fail, the test is the NutraGro with a prayer for it to fail, and a calibration group is without NutraGro and without prayer. That way, if there is a difference between the first two groups, the third group can help judge whether the NutraGro really failed (as opposed to just was somehow statistically signifantly different) with the prayer for it to fail as compared with without. 82.113.106.90 (talk) 20:20, 8 April 2010 (UTC)

I endorse Edison's response above. (The original poster asked a similar question here on February 24, in case anyone feels like reviewing the answers given back then.) Comet Tuttle (talk) 20:53, 8 April 2010 (UTC)

One would think that such a meddlesome deity would be liable to bless the NutraGro plant with outrageous growth, in an attempt to foil your experiment. AlexHOUSE (talk) 22:22, 8 April 2010 (UTC)

If prayer works, then any rigorous experiments to test the reponse of people or objects to prayer are invalid. See efficacy of prayer. ~AH1^(TCU) 03:28, 10 April 2010 (UTC)

Apples numbing the lips.

Hey Ref Desk. Every time I eat an apple whole, my lips become somewhat numb. They feel stiff and feelingless against each other, something like rubbing your fingers together when you have paresthesia in your hand. Sometimes I catch myself drooling a little bit, and the effect usually fades away gradually over the next fifteen or twenty minutes. What's the deal? AlexHOUSE (talk) 22:14, 8 April 2010 (UTC)

This is NOT medical advice (I am not a doctor and cannot diagnose you!), but it sounds superficially to me like you are allergic to the apples or something on them. I suggest talking to a doctor or allergist about this—they can tell you for sure, and whether it means you should avoid or be careful with apples or not. Apple allergies are apparently not uncommon, I gather from Googling. --Mr.98 (talk) 22:31, 8 April 2010 (UTC)

See also Cross allergy. 75.41.110.200 (talk) 23:04, 8 April 2010 (UTC)

A quick search of "cross allergy" led me to Oral allergy syndrome, which seems pretty close. Thanks! AlexHOUSE (talk) 23:10, 8 April 2010 (UTC)

People with allergy towards birch pollen often experience those exact symptoms, which are caused by cross allergy, as stated above. Other vegetables that might provoke similar symptoms are raw carrots, pears, cherries, peaches, hazel nuts. Heat treatment of the vegetables tends to remove the problem, e.g. boiled carrots cause no symptoms, raw carrots do. If you have are worried about this, and in particular if you experience other symptoms than those you have described, you should seek medical advice, and not the advice of random strangers on the internet. --NorwegianBlue ^talk 00:21, 9 April 2010 (UTC)

Oh, I'm not the least bit worried about it; my life will continue on I'm sure. Thank you though :) AlexHOUSE (talk) 17:08, 9 April 2010 (UTC)

Why do we need vitamin D?

Everyone knows that vitamin D is used by the body to take up calcium and transport it to the bones. Vitamin D also plays a role in the immune system. However, if you look more closely at the precise role of vitamin D here, what you see is that vitamin D only acts as a switch to turn on the production of certain proteins that do the real job.

We also know that vitamin D can only be made by organisms using UV light. The vitamin D we can get from food (e.g. fish) is also ultimately derived from UV light. The question is why all organisms have made the functioning of certain important processes dependent on a unessential substance that can only be made in a cumbersome way. Count Iblis (talk) 23:21, 8 April 2010 (UTC)

You have to consider that when this developed, all humans lived in the tropics, where access to UV light just wasn't an issue. Access to anything that comes from food, on the other hand, would have been a problem whenever a period of famine occurred. So, with vitamin D, unlike other substances, there was a backup plan for when the food containing it (like fish) became unavailable. StuRat (talk) 00:52, 9 April 2010 (UTC)

It goes back even further than that. Unicellular organisms have been taking advantage of photoconversion to make Vitamin-D analogs for millions of years. An ancient example of this process is that ergosterol in the cell membranes of some primitive organisms absorbs UV light more readily than nucleic acids, thus providing protection against a mutagen. Over evolutionary time, these compounds (and other useful molecules like them) were adapted for additional purposes. Quite elegant, really. What makes you see it as "cumbersome"? --- Medical geneticist (talk) 01:36, 9 April 2010 (UTC)

Vitamin D is a hormone. Like most hormones, it simply serves as a signal to activate some processes and repress others. And like most hormones, it acts upon many different systems in the body. And like most ancient and conserved hormones, the relative importances of various functions varies among organisms. What else would you like to know? alteripse (talk) 04:45, 9 April 2010 (UTC)

It is not clear to me why such signalling functions are needed at all for the processes regulated by vitamin D. In case of other hormones, there is a feedback loop regulating the production of the hormone. E.g. The new research has found that t-cells won't mobilize and will lie dormant unless they can find vitamin D. The only way I can make sense of this is by assuming that for some reason the body wants to ration the energy resources spend on the immune system in the absense of adequate vitamin D levels. Count Iblis (talk) 14:48, 9 April 2010 (UTC)

I am not sure how best to answer this. The control systems for hormones are typically complex, not based on simple feedback of a protein product. This is especially true for steroid hormones. We certainly do not understand all the pieces of the control systems for most hormones. As the role of vitamin D in immune regulation has only recently been appreciated and is an area of investigation, no one can provide a full and complete model of the vit D immune system interactions. Consider other steroid hormones that affect the immune system, such as cortisol and estrogen. We have known for decades that they can suppress inflammation and autoimmune activation, but we still have a long way to go to understand all the relevant signals. There is a broad heuristic model that divides many physiologic processes into anabolic and catabolic directions. Catabolic processes predominate in conditions of severe stress, illness, starvation, and can be simplistically imagined as "making resources available for fighting the infection or illness at the expense of growth, storage, and repair". I am sure you can fit some of the vitamin D-dependent processes in there as well. alteripse (talk) 17:32, 9 April 2010 (UTC)

Thanks everyone for their detailed answers. If I consider Alteripse's model and also consider that the latest research seems to indicate that we need several thousands of IU of vit. D per day and you can't get that from food alone, only from the Sun (or from supplements, but these were not available to Stone Age Man), then it seems that a prolonged lack of exposure to the Sun is used by the body as a signal that something is wrong. Also, when the Sun is below 40° above the horizon, there won't be enough UVB radiation for the skin o be able to synthesize Vit. D at all. So, perhaps the body also uses lack of Vitamin D as a signal that the Winter season is on its way? Count Iblis (talk) 21:37, 10 April 2010 (UTC)

Sexual attraction to skeletons

Is there a recognized scientific name for people who are sexually attracted to/aroused by skeletons? —Preceding unsigned comment added by 140.198.32.131 (talk) 23:58, 8 April 2010 (UTC)

In Still life painting there is something called the "nature morte," which contains a skull. I find this line in that article:

"Also starting in Roman times is the tradition of the use of the skull in paintings as a symbol of mortality and earthly remains, often with the accompanying phrase Omnia mors aequat (Death makes all equal)." Bus stop (talk) 00:03, 9 April 2010 (UTC)

Necrophilia is close, but is defined as attraction to corpses and dead things, not necessarily skeletons. Intelligentsium 00:08, 9 April 2010 (UTC)

A male skeleton can have a "boner" or Baculum. Cuddlyable3 (talk) 00:24, 9 April 2010 (UTC)

Not if it's human. StuRat (talk) 00:50, 9 April 2010 (UTC)

Isn't sexual attraction to skeletons the logical end of the "you can never be too thin" quote ? StuRat (talk) 00:50, 9 April 2010 (UTC)

Since necro is from greek, and the greek word for skeleton is skeleton, I guess it would be skeletophillia. Ariel. (talk) 07:27, 9 April 2010 (UTC)

Good deduction, but I have a feeling in my bones that its spelt: Skeletophilia --79.76.236.198 (talk) 19:51, 9 April 2010 (UTC)

What would it be called if you are only attracted to the cervical vertebrae?Edison (talk) 00:28, 10 April 2010 (UTC)

Not what you are thinking --79.76.236.198 (talk) 02:08, 10 April 2010 (UTC)

April 9

Use of imaging in cancer diagnosis

How can imaging alone determine the source of cancer in the body? I've just learned that an elderly distant relative has been diagnosed with cancer in two different parts of the body; based on imaging alone, the oncologist believes that it originated in one part of the body, even though it's apparently no more pronounced there than in the other part. Please don't take this as a request for medical advice; I simply can't understand how images can reveal that one spot of cancer is the source and a similar spot of cancer is the result of metastatis. Nyttend (talk) 01:09, 9 April 2010 (UTC)

Not necessarily images, but certain tests of immunohistochemistry can identify metastases. 76.235.109.131 (talk) 01:15, 9 April 2010 (UTC)

(after EC) The oncologist is probably using additional sources of information (clinical judgment and knowledge of typical patterns of cancer incidence and metastasis) in conjunction with the imaging to come to a "most likely" explanation. Additional confirmatory tests, such as a biopsy (and the aforementioned pathology studies), are generally involved in making a definitive diagnosis. --- Medical geneticist (talk) 01:18, 9 April 2010 (UTC)

Too add to that, the cancer may have particular characteristics (shape, rate of growth, density on a CT scan etc.) that identify it as probably originating from a particular organ/part of the body. 131.111.185.75 (talk) 09:22, 9 April 2010 (UTC)

If the tumor is avascular (which I think all if not most are, someone clarify that for me) then PET scans can look for high concentrations of radioactive glucose given to a patient and see where it builds up. Avascular tumors can't respire aerobically. Presumably you can see where the biggest build up of glucose is to see where the cancer originated, as the tumor should be largest there? I'm not sure of this, so I'll let someone with formal medical training check it :) Regards, --—Cyclonenim | Chat  17:46, 10 April 2010 (UTC)

Imaging alone is very helpful in determining the source of cancer, although not 100% definitive. CT scans and FDG-PET scans are the most helpful. Radiologists are specifically trained to look out for characteristic patterns associated with different cancers. With the clinical context, the radiologist can often give the likely diagnosis.

Certain cancers are more common than others; common ones include breast cancer, lung cancer, prostate cancer and colorectal cancer. If, for example, a scan shows an abnormal mass in the lung and an abnormal mass in the adrenal gland, this is far more likely to be a primary lung cancer with metastasis to the adrenal, rather than a primary adrenal cancer with metastasis to the lung. Axl ¤ [Talk] 01:13, 11 April 2010 (UTC)

Causality

How does information travelling faster than the speed of light disrupt causality? I've read this mentioned many times, but I haven't seen any justification for it. Thanks. 173.179.59.66 (talk) 02:41, 9 April 2010 (UTC)

Basically, if you can send a signal faster than the speed of light, and if the means of doing so works the same in all reference frames, then you can also send information back in time. So then someone from 2100 could send you a signal telling you to kill his grandfather, and you get the grandfather paradox. See tachyonic antitelephone for how this would work. --Trovatore (talk) 02:44, 9 April 2010 (UTC)

(ec) I'm no Gandhi but I bet it is because there is no single "now" but only frames of "now" and if you could send information faster than light then you could disrupt all into someone's frame. 82.113.121.111 (talk) 02:47, 9 April 2010 (UTC)

reading the above (first to post in edit conflict) it seems I was right :) maybe I am a gandhi... 82.113.121.111 (talk) 02:47, 9 April 2010 (UTC)

I live on Alpha Centauri and have your cat under my care. Your cat dies, and I send a faster-than-light message to you (on Earth) telling you that it died. That message--the effect of the cat dying--would arrive before you would see the cat die if you had an enormous telescope. That can't happen; the effect cannot precede the cause in any reference frame. --99.237.234.104 (talk) 03:02, 9 April 2010 (UTC)

Trovatore's answer is correct but may not be clear enought. The point is that for any faster than light movement there is always some reference frames in which that movement is seen as motion backwards in time which violates causality. That happens because of the relativity of simultaneity. In other words, if you can move faster than light then you also can move backwards in time. Dauto (talk) 03:24, 9 April 2010 (UTC)

It's a little subtler than that. Just going backwards in time in someone's coordinate system isn't enough in itself. Suppose I can send a signal that, in your coordinate system, leaves from Earth in January, 2012, and arrives at Alpha Centauri, around 4 light-years away, in January, 2011.

That doesn't get you the grandfather paradox, because if you send the signal back to Earth the normal way, it won't arrive until sometime in 2015. So you can't send a signal back to cause it not to be sent.

To close the loop, you have to repeat the trick, and send the signal back to Earth, if not backwards in time, then at least at four times the speed of light or better.

That's why I specified frame-invariance. It's logically possible that there might be a distinguished frame of reference in which you could send a signal faster than light, but because the method is not frame-invariant, you still would not be able to get causal loops. That would, of course, contradict relativity, but only in regimes where it's never been tested. --Trovatore (talk) 05:30, 9 April 2010 (UTC)

@99.237.234.104: Wouldn't you be able to account for the speed of the message and, correcting for it, see that cause didn't precede effect?

@Dauto: Would you be able to show me how you get that mathematically? Otherwise I'd just be taking your word for it. 173.179.59.66 (talk) 04:37, 9 April 2010 (UTC)

The relevant equation is the Lorentz transformation. Specifically, Assuming the faster than light signal started from space-time origin - that is x=0, and t=0, and endded at x=X, and t=T where X>cT, and plugging these values at the lorentz transformation $t'=\gamma (t-{\frac {u}{c^{2}}}x)$ you find that the same signal is seen from the point of view of the second observer as also starting from space-time origin and anding at $t'=\gamma (T-{\frac {u}{c^{2}}}X)$ which may be negative for some values of u<c which is the relative speed between the two observers. Dauto (talk) 14:25, 9 April 2010 (UTC)

The Lorentz transform article explains both the simple formula and the experimental justification for the mathematical description of different refernce frames. Nimur (talk) 11:51, 9 April 2010 (UTC)

Right, thanks. 173.179.59.66 (talk) 15:03, 9 April 2010 (UTC)

crash landing fatality rates - higher for helicopters or fixed-wing aircraft?

Seeing the news that a NATO helicopter in Afghanistan went down overnight with 4 presumed deaths got me wondering about crash-landing survival rates - if I'm military personnel, so I have a better chance of surviving a helicopter being shot out from under me / suffering severe mechanical failure or a fixed-wing aircraft? Numbers please, not speculation. I can do that myself! 218.25.32.210 (talk) 06:38, 9 April 2010 (UTC)

You would not believe what we have. To compile these statistics, however, one would need to go over those numbers to set up one's own graph. What we are looking for is the survival rate of crashed aircraft, rotary versus fixed. You do not explicitly state if you would like to discriminate based on "crash landing"; some aircraft that are shot at do explode in the air. I have been able to locate a source for your desired information: This forum's second poster has a lot of sources posted, and may be able to help you. Please note these are statistics for one year, and, in addition, concern the civillian market. What should be clear, however, is that the accident rate (not casualty rate) with helicopters is so vastly higher than airliners, that it would take great statistical deviance to suggest there is not also an accompanying casualty rate. This is speculation, of course, but it is educated. I could not produce numbers for helicopter accident fatalities/casualties versus fixed wing numbers, but I think these should be easy to gather from some of the sources mentioned in that link. 88.90.16.251 (talk) 08:21, 9 April 2010 (UTC)

The bit about "great statistical deviance" does not make sense. There is no particular statistical reason to expect the accident rate, and the survivability rate when accidents do happen, to be correlated. --Anonymous, 23:05 UTC, April 9, 2010.

You might want to compare helicopters with single engine planes, as they are similar in being unable to fly after an engine failure (even twin rotor choppers crash if either fails). This would allow you to compare the difference in the airframe only. StuRat (talk) 12:14, 9 April 2010 (UTC)

Many single-rotor helicopters, however, are multi-engine aircraft. 64.238.255.250 (talk) 14:11, 9 April 2010 (UTC)

An engine failure in either an airplane (even a single-engine type) or a helicopter would not necessarily result in a crash with damage and/or injuries: an airplane can glide down for a dead-stick landing, even in the case of a complete engine failure, and a helicopter can autorotate to a more-or-less controlled landing. In both cases, much depends on the skill of the pilot in dealing with this type of in-flight emergency.

Speaking of pilot skill, I strongly suspect that the much higher accident rate of helicopters vs. airplanes has to do in large part with the fact that a helicopter is much harder to fly than an airplane -- it's got four primary controls (cyclic, collective, rudder pedals, and throttle) vs. an airplane's three (stick, rudder pedals, and throttle), and what's even more important, it's not inherently stable like an airplane, so you can't fly it "hands off", you have to positively control it at all times and correct for any incipient divergence in the flight path. If you're flying a chopper, you can't ever let your attention wander, or you're as good as dead. 24.23.197.43 (talk) 05:25, 10 April 2010 (UTC)

In the case of engine failure in a helicopter or single-engine plane, you'd better have a good landing spot nearby. If you're over water, mountains, forest, etc., you may be SOL. And, you also need a certain amount of altitude for the auto-rotate function of a chopper to kick in. StuRat (talk) 05:43, 10 April 2010 (UTC)

Yeah, that too. My point is, an engine failure doesn't turn an aircraft into a pile of scrap metal falling from the sky -- it turns an airplane into a glider, and a helicopter into an autogyro, so a pilot (often) has a chance to make a safe engine-out landing. BTW, engine failure over water is no problem if you're flying a seaplane or amphibian aircraft. 24.23.197.43 (talk) 06:19, 10 April 2010 (UTC)

Re-focusing photographs

Could it be possible for an out-of-focus photo to be brought into focus by some kind of algorithm or equipment? It seems to me that all the necessary information must be in the photo, and although the information is scrambled up, the scrambling must occur in a predictable way. Presumably I'm wrong? "Sharpen" filters that work by edge-detection are not at all what I mean. 81.131.18.168 (talk) 10:44, 9 April 2010 (UTC)

See deconvolution microscopy, and more generally deconvolution for the theoretical basis of this approach. My impression is that detailed information is required about the whole optical system for this to work effectively, making it impractical for normal photography, however I am no expert on optics. I know that one approach in biological microscopy is to image a perfectly spherical bead of known diameter, and use this to work out the deconvolution parameters needed. 131.111.185.69 (talk) 11:19, 9 April 2010 (UTC)

(ec) Computational photography studies that problem. Here are a few links you might find interesting: Light fields and computational photography, Synthetic Aperture Focusing using a Shear-Warp Factorization of the Viewing Transform, and the MultiCamera. It really helps to have redundant information, (for example, many separate photographs - though there are other ways to have redundant information), so that an algorithm can extract additional information to help focus the image. This video, Synthetic Aperture focusing, shows a series of processed results from a "single image" generated by the multi-camera (you can consider this a single camera with a huge synthetic aperture, or you can consider it 128 cameras with normal apertures). In either case, though, these algorithms require additional (redundant) information which is not contained in an ordinary photograph - your post implies that de-focusing is "information scrambling" (which is correct, but your terminology is a bit imprecise.) However, your assumption that this "scrambling" is predictable is not exactly right - it's only predictable if we have additional information - how the image was defocused, or some knowledge about the 3D setup of the scene, etc.

If you have a fairly powerful computer (~ 1 GB of RAM and a pretty fast processor), you can use this browser-based demo to play with synthetic-aperture focusing on a series of test photographs. If you're a programmer, the project source code is available, so you don't have to run this inside a web-browser (for obvious performance reasons!) Nimur (talk) 11:23, 9 April 2010 (UTC)

If you know exactly how the blur occurred then you can calculate a point spread function, and do the inverse convolution. However there is still a problem of noise. Any noise will be amplified. compression artifacts will be counted as noise too, so you need to perform this on a non compressed and high quality image. Without knowing the way the picture was corrupted, you can attempt blind deconvolution. As far as I know there were not any stable algorithms or methods using a limited CPU to get a good result. Graeme Bartlett (talk) 12:41, 9 April 2010 (UTC)

Adaptive optics may also be relevant. StuRat (talk) 13:01, 9 April 2010 (UTC)

Yes, by deconvolution or Blind deconvolution. There is or was some free software on the internet somewhere that does this. This link seems to relate to non-free software http://www.quarktet.com/BlindDecon.html 78.147.131.74 (talk) 21:00, 9 April 2010 (UTC)

Decon will take out motion blur, but it will fail abysmally in most cases because depth-of-field blurring is non-linear with respect to pixel x-y location (it is dependent on depth of field (z), which is an external variable which we have no knowledge about from a single image). In other words, the convolution filter is not invertible (or requires nonlinear inversion). To put another way, consider this example. Imagine you photograph an object with a fuzzy edge (like a diffuse mist). Even when focused, you still image a fuzzy edge. An equivalent point-like object in the same photograph, but out-of-focus, will look exactly the same in terms of x-y pixel locations and intensities. So, how can you construct a decon filter to preferentially "point-ify" the point, and preserve the mist's fuzzy edge condition? You need to know something about the scene - the actual distance to each object; and you also need to know something about the optics - the focal depth of field. This information isn't available from a single image. Nimur (talk) 21:16, 9 April 2010 (UTC)

The blind deconvolution software has a bash at it anyway. 84.13.21.95 (talk) 23:16, 9 April 2010 (UTC)

Using a coded aperture in the lens can help reduce some of the ambiguity and make the deconvolution a little less ill-posed. See here for some dynamic refocusing samples and a paper: http://groups.csail.mit.edu/graphics/CodedAperture/ . 128.12.174.253 (talk) 18:31, 10 April 2010 (UTC)

Realistically it can't be done. Unblurring is an example of what mathematicians call an ill-posed problem, meaning a transformation that isn't invertible. The difficulty is that blurring an image results in a loss of information, and even if the way the information is lost is totally understood, there is no way to get it back. (This answer oversimplifies the story a bit, but the reality is that there are no good unblurring algorithms that work in a broad range of situations.) Looie496 (talk) 05:28, 10 April 2010 (UTC)

I saw some before and after photos of deconvolution of blurred images in a textbook once, so I have to disagree - I believe it can be done, especially when you know or can estimate (or use trial and error) the quantitative extent of the blurring. 84.13.169.129 (talk) 10:38, 11 April 2010 (UTC)

Nimur is correct that depth-of-field blur cannot be reversed. However the other sources of blur that can be corrected by deconvolving a point-spread function may be lens imperfections, simple defocus (not depth-of-field variation), or limited scan (e.g. TV) bandwidth. This is theoretically possible assuming analog (not digitised) information with sufficient signal-to-noise ratio. A 2-D point spread function must be used, which is not possible close to the image borders or for blur of objects in relative motion. Cuddlyable3 (talk) 11:09, 11 April 2010 (UTC)

why are car wheels the size that they are?

Why are car wheels the size that they are, instead of much bigger or much smaller?

Elaboration

why are car wheels the size that they are... I don't understand it, as to my mind, there are two possibilities: - the graph of "size" (x) versus whatever you're optimizing (y) slopes like this: / up until the size of the car Then the wheels should be as tall as the car. If the sloping continues, the wheels should be much taller than the car, maybe as tall as a person. - the graph of "size" (x) versus whatever you're optimizing (y) slopes like this: |\ where the initial jump happens when you get above the size of pieces of gravel or microholes in the pavement or whatever In that case the wheels should be tiny, like wheels on rollerblades, although you may need more of them to support the car. Either way, to my mathematical, binary inclined mind, I can only imagine "bigger is better" or "smaller is better" -- I can't imagine what, if anything, the current wheel size can POSSIBLY optimize. Does anyone know? What would happen if the wheel size were slightly bigger or slightly smaller? (ie whatever y axis you're optimizing must have a smaller value when x - the wheel size - is even slightly smaller or bigger; hence the fact that it is the size that it is: at the point of the current actual wheel size, the graph must look like this: /\ where if you make it (x, the wheel size) either bigger or smaller, the y-value (whatever you're optimizing) is reduced. Can someone tell me what exactly the y really IS? Thank you.84.153.199.127 (talk) 12:04, 9 April 2010 (UTC)

This is exactly why every instance of a claim of "designed without compromise" - a car industry favourite - boils my piss. Tyres (like most things) are optimised against a basket of variables and the sweet spot is a compromise. Some example factors for car tyres: size affects rolling resistance; gearing choices; axle speeds; weight; cost; space required to accommodate the four wheels and the spare; ability of the wheel to lend suspension/damping to the vehicle; ability to negotiate defects in road surfaces &c&c&c. None of this is enough to pin why the sizes are as we're familiar, but merely to suggest that there's a lot of complexity, and probably a lot of pragmatism, in the choices. And that being the case, a simple x versus y analysis will be insufficient to answer the question. --Tagishsimon (talk) 12:43, 9 April 2010 (UTC)

The way this type of thing usually works out is that there are some advantages to being bigger, but most of that advantage comes in at the initial increases in size, with diminishing returns for further increases, and the same is true for being smaller. The result is that there's some optimal size or range of sizes in the middle. But let's look at some of the advantages of small wheels and large wheels:

Small Wheel Advantages:

1) Less expensive.

2) Easier to carry a spare.

3) Easier to change.

4) Less rotational inertia, which makes turning and stopping easier.

Large Wheel Advantages:

A) More suspension, for a softer ride.

B) Better at going over obstacles.

C) They "look cool".

D) Since they average out the friction over a larger contact area, they tend to slip less.

Of those, perhaps not being able to change a wheel over about 30 inches pretty much sets an absolute limit on sizes. There are wheels larger than that, on industrial equipment, but those require a team of workers and maybe some specialized machinery to change, so aren't practical for a normal car. StuRat (talk) 12:47, 9 April 2010 (UTC)

I think the simplest explanation would be that they are designed to optimize versatility for cars of a certain size. People use cars under a lot of conditions and different speeds. You don't want something that is only optimized to one set of conditions that fails under others. You want something that is a good generalist. The only times you want super-optimized wheels are for very constrained conditions—like Formula One tires, which are meant to do basically one thing and one thing only under controlled conditions. Extreme optimization for specific situations is not always an advantage unless the conditions are entirely predictable. (Human beings are, incidentally, pretty well optimized for versatility. We can do a lot of things pretty well. Most animals are by comparison optimized for specific ecological niches. Humans can go basically anywhere.) --Mr.98 (talk) 15:53, 9 April 2010 (UTC)

I tried living with the giant tube worms on an undersea volcanic black smoker, but I didn't care for it. :-) StuRat (talk) 16:03, 9 April 2010 (UTC)

Two more points. Large wheels simply weigh more. And, more important, they get in the way of things. For many cars today, if the wheel diameter was increased about 30-40% they'd need to poke above the hood (but they'd still neet to be covered for safety reasons). Do that a little and it looks weird; do it much and you increase aerodynamic drag. Also, the front wheels also need to pivot to angle sideways for steering, so larger wheels would mean you'd lose available width in the engine compartment. (Similarly, on vehicles like buses and streetcars, especially the low-floor, wheelchair-accessible types, a limiting factor for wheel size is how far the wheel wells can protrude into the passenger compartment without interfering too much which where the seats can be put.) --Anonymous, 23:17 UTC, April 9, 2010.

And what about the trend, too?

There's another facet to the original question as well. Look at vehicle tyres from 1920s, you see basically upsized bicycle wheels and tyres -- lots of wheel, not much rubber. 1950s, you see smallish wheels and lots of rubber, and the ratio of height to width is .80 or .75 on just about every passenger sedan in the world.

Mid-to-late 80s or thereabouts, the pendulum began to swing back, wheels got bigger / rubber got smaller, and a 60-series tyre was considered "low-profile" -- and it was probably mounted on a 16- or 17-inch rim, even for passenger cars.

Today 18-19-inch rims are not uncommon, and it really doesn't look like there's more than 3 inches of sidewall showing -- in other words, except for the width needed to support the weight, we're back to bicycle tyres. Aspect ratio 45 -- what's up with that?

Clearly, the trend is to larger and larger wheels, and less and less air volume. Anybody want to bet on whether 22-inch wheels and 2-inch sidewalls are commonplace in another 5 years?

If 20-inch rims and 3-inch tyres are wonderful, why didn't we just keep using them for the past 40 years??

(Part of the answer will probably have to do with improvements in suspensions, which shifts "responsibility" for pavement bumps away from the tyres and onto the struts, but that can't be the whole story, can it?)

DaHorsesMouth (talk) 22:46, 9 April 2010 (UTC)

Making hybrid fruit trees

Last year, I planted a couple dwarf peach trees on my parents farm. Basically, they're just normally sized peaches grafted on to a dwarfing rootstock. I knew they were supposed to be small, but to my surprise, they're already making blossoms this year and by June or July, we should have some peaches. The farm is also covered in thousands of wild plums that start blooming this time of year too. Plums and peaches are closely related and they've made hybrids before. So that gave me a crazy mad scientist idea.

I found a healthy looking blossom on the largest peach tree and before it opened, I carefully tied a plastic bag over it with a twist-tie (being careful not to damage the plant). This should keep foreign pollen out of the blossom. It just opened up today and my plan is to transfer pollen from one of the plums into the peach blossom to make a hybrid plant. If all goes well, sometime in the next decade I'll find out what my frankenstien fruit tastes like.

I just want to know if I'm doing anything wrong here. Are peaches able to pollinate themselves from the same flower? If so, that will throw a wrench in my whole plan. Also, I'm concerned about growing my new fruit from a seed which I hear doesn't always work well with fruit trees since they've been crossed and selectively bred so extensively.

Does the reference desk have any advice for a newbie mad scientist attempting to make a new species?

63.245.168.34 (talk) 14:40, 9 April 2010 (UTC)

I suspect that something as common as those two would have already been cross-bred, if it's both possible and desirable to do so. StuRat (talk) 15:58, 9 April 2010 (UTC)

There are a number of stone fruit (Prunus) hybrids, including the pluot, the plumcot, the aprium, the nectacotum and the peacotum. I'm not sure if there is a name for it, but doing a Google search for "plum peach hybrid" reveals a number of sites, including some indicating that a variety called "Tri-Lite" is commercially available. Regarding crossing, a quick Google search indicates that most varieties of peach are self-fertile, however there are some which are self-sterile and some which are male sterile. One possibility is to attempt to excise (pluck) the stamens from the flowers you want to cross after they become visible, but before they mature. If you're able to catch them before they drop pollen, your plastic bag trick might work. -- 140.142.20.229 (talk) 17:02, 9 April 2010 (UTC)

Uh oh. I better do that ASAP. I actually covered two flowers with a bag and only one has opened yet. There's dozens of flowers on the tree, though, so if I need to try again, I can start with another flower. Thanks for the heads up! 63.245.168.34 (talk) 23:26, 9 April 2010 (UTC)

The statement "attempting to make a new species" requires addressing. It is unlikely that you will be able to produce a new species. Speciation occurs over many generations, and is a result of selection and evolution rather than a one-time cross. The offspring will, more likely than not, be infertile due to chromosomal imbalances or other issues. While it is possible with plants, and certainly some species are a result of hybridisation, your experiment will probably fail to produce a distinct species. Intelligentsium 03:38, 10 April 2010 (UTC)

I was aware of that. I know that I'm not going to make the textbook definition of "species", but it'll at least be making something completely new an unheard of. If the offspring is infertile, will it still make fruits? I don't mind if it's infertile, I can propagate it by grafting. 63.245.168.34 (talk) 06:13, 10 April 2010 (UTC)

Darwin's Origin of Species contains a pretty extensive discussion of what happens when plants are crossbred. A newbie mad scientist could probably benefit from reading it. Looie496 (talk) 05:21, 10 April 2010 (UTC)

Collision

Suppose there's an elastic collision involving two billiard balls. How would we write out the conservation of energy in this case? Would we have two seperate equations, one for kinetic energy and one for rotational energy, or would the sum of the two be conserved? 173.179.59.66 (talk) 15:14, 9 April 2010 (UTC)

The sum of the two is conserved. In practice, when solving problems, it is not wise to write down the conservation of energy equation as that will yield messy equations. Instead, you should transform to the center of mass frame where energy conservation can be automatically implemented in the conservation of momentum equations: The magnitude of the momenta stay the same. Count Iblis (talk) 15:32, 9 April 2010 (UTC)

The physics of billiards is more complex in the penal regime of The Mikado where:

“ The billiard sharp who any one catches,

His doom's extremely hard —

He's made to dwell —

In a dungeon cell

On a spot that's always barred.

And there he plays extravagant matches

In fitless finger-stalls

On a cloth untrue

With a twisted cue

And elliptical billiard balls!

”

Cuddlyable3 (talk) 17:28, 9 April 2010 (UTC)

@the Count: How does that work? In the centre of mass frame, conservation of linear momentum gives m₁v₁ + m₂v₂ = 0 before and after the collision, and conservation of angular momentum gives I₁ω₁ + I₂ω₂ = constant (can I have confirmation that this doesn't equal zero?). Where would energy come in? 173.179.59.66 (talk) 18:30, 9 April 2010 (UTC)

You may also have to include orbital angular momentum to have an accurate prediction of the outcome of a shot. The energy equation is E = 1/2 * (m₁v₁²+m₂v₂²+I₁ω₁²+I₂ω₂²). Note that a) It can get very messy to solve the equations, b) Assuming conservation of energy might lead to imprecise results, and c) You still need to stipulate some contact condition. (may be a non-slip condition). Dauto (talk) 18:49, 9 April 2010 (UTC)

Fine, but how do you get that the magnitude of the momenta will be the same? 173.179.59.66 (talk) 00:46, 10 April 2010 (UTC)

Perhaps if it makes my question clearer, how were equations (1a) - (2b) determined? 173.179.59.66 (talk) 02:43, 10 April 2010 (UTC)

lol I forgot to link my document: http://www.cns.brown.edu/physics/userpages/staff/Gerald_Zani/billiards/billiard1.pdf. 173.179.59.66 (talk) 05:46, 10 April 2010 (UTC)

Physiological diplopia

I'm curious about the prevalence of the ability to (consciously) see both eyes' images of an object not in the plane of the object upon which one's gaze is directed (more precisely, the Panum's fusional area or horopter). Most people I've checked with have this property, but a few report not being able to see two copies of anything ever, such that (for instance) they can hold up two thumbs, one at arm's length in front of the face and one near the nose, and fully obstruct the far thumb with the near despite having both eyes open. Others report that the near thumb is somehow indistinct or transparent such that the far thumb is visible, so that it seems they are constructing one image from the two eyes but which combines what is visible to each. (That is of course normal for the object one is regarding, but not so much for objects that are much closer.)

An optometrist I consulted called the normal tendency to see double in this fashion physiological diplopia, which does seem to be an accepted term for it, but he didn't know of any studies of or figures about how many people don't exhibit it normally. I think having an article on this would be wonderful, but I haven't found anything online other than that it is considered normal, so any actual references on the subject would be appreciated (as would be just the numbers). --Tardis (talk) 15:47, 9 April 2010 (UTC)

To your survey of perceptions of near and far thumbs I can add a category: one has interest focussed on the near thumb and the far thumb becomes two thumbs on either side of the near thumb. Wikipedia has articles on Diplopia, and Binocular vision that describes tests for disorders of binocular vision such as the tropias. Useful references may be a tutorial on Binocular Vision and the neuroscience of binocular rivalry. Cuddlyable3 (talk) 17:14, 9 April 2010 (UTC)

Two copies of each thumb when focused on the other is part of the standard behavior. I'll look at those references, thanks; have they anything about the proportions? --Tardis (talk) 17:32, 9 April 2010 (UTC)

Obviously this is not to be mistaken for a medical diagnosis, but what the question made me think of is amblyopia. --Anonymous, 23:22 UTC, April 9, 2010.

Coordinate system

What is the reference coordinate system in our universe with respect of which acceleration of moving bodies is measured? —Preceding unsigned comment added by Amrahs (talk • contribs) 16:22, 9 April 2010 (UTC)

Any inertial coordinate system will do. Taking the first derivative of position destroys the knowledge of the origin of the coordinate system (making it an affine space), and so velocities do not depend on the origin. Taking another derivative destroys the knowledge of the (uniform, inertial) motion of the coordinate system (or, equivalently, the origin of the velocity space), and so accelerations do not depend on one's reference frame so long as it is not accelerating. Of course, if you're speaking relativistically (even in SR) then things like time dilation interfere with this constancy. --Tardis (talk) 16:33, 9 April 2010 (UTC)

The idea of an inertial coordinate system doesn't really exist in General Relativity. An accelerating object is equivalent to a non-accelerating object in a gravitational field. If you want to define a coordinate system, you basically have to choose an object to do everything relative to. Any object will work, but some may be more convenient than others for certain problems. Alternatively, you can work relative to the cosmic microwave background, which isn't an object, per se, but can be used in the same way. --Tango (talk) 19:53, 9 April 2010 (UTC)

Adiabatic Expansion

Suppose air at pressure P₁ and sp. volume v₁ is adiabatically expanded under STP to P₂ and v₂. Now, using adiabatic process formula, P₁v₁^k=P₂v₂^k (Initial conditions are known.) Which value to be used as final condition? Either value of P₂=101325N/m² to be used or density=1.2256kg/m³? —Preceding unsigned comment added by Giganticvis (talk • contribs) 16:22, 9 April 2010 (UTC)

Both, assuming that by "under STP" you meant "to STP". If this makes the equation overspecified, then you have a mistake somewhere, possibly in the statement that the expansion was adiabatic (not all initial states can be changed adiabatically to STP). --Tardis (talk) 16:31, 9 April 2010 (UTC)

I should add that specifying the temperature and pressure of an ideal gas determines its density; that's why you can use the density at all. Perhaps you knew that. --Tardis (talk) 16:36, 9 April 2010 (UTC)

Chemistry question

Hellow! Could you tell me the stoichiometric requirement of lime(Cao) for neutralizing Sulphurdioxide gas please along with chemical equation? —Preceding unsigned comment added by Krishvanamali (talk • contribs) 17:47, 9 April 2010 (UTC)

See Calcium Oxide and Sulfur dioxide for chemical formulas, and stoichiometry and Chemical_equation#Balancing_chemical_equations for a description of how to calculate stoichiometric ratios. --Jayron32 17:52, 9 April 2010 (UTC)

The chemical equation for this reaction is CaO+SO₂→CaSO₃. You can calculate the mass ratio from there. 24.23.197.43 (talk) 05:38, 10 April 2010 (UTC)

Can I drink dishawshing liquid?

Gene Weingarten was asking a similar question in one of his columns devoted to customer support experiences.

Specifically, if I need to use a cup, glass or mug right away after washing it because I've run out of clean ones, and despite my best efforts to rinse out what I washed, it still has soap in it, I can't ever recall any ill effects. What I'm drinking tastes kind of soapy.

Normally I turn the item upside down where the dishes dry. sometimes it doesn't drain because it tipped over, and the same thing happens.Vchimpanzee · talk · contributions · 18:10, 9 April 2010 (UTC)

Drinking enough dish-washing liquid would probably make you vomit or even kill you, but the tiny amount left on the dishes isn't likely to do any harm. In fact, one of the main ingredients, phosphates, is found in many foods and drinks. StuRat (talk) 18:15, 9 April 2010 (UTC)

Soaps can be both a purgative and a laxative, so eating sizable quantities of detergent may not kill you, but it may give you diarrhea or make you puke. However, its a matter of degree. Small amounts of residue left on the dishes will have no effect at all on your health; while downing an entire bottle at a draught may result in some ruined underwear. --Jayron32 18:50, 9 April 2010 (UTC)

Or, while not killing you, it may make you wish you were dead. Googlemeister (talk) 18:52, 9 April 2010 (UTC)

Purely original research, but I can tell you with absolute certainty that, from personal experience, in sufficient quantities it acts as a strong purgative. AlexHOUSE (talk) 19:22, 9 April 2010 (UTC)

And what possessed you to drink large quantities of dish-washing detergent ? StuRat (talk) 17:18, 10 April 2010 (UTC)

The bottle of dishwashing liquid in my kitchen has warning notices saying to keep it away from children and not to mix it with bleach, get it in your eyes, or use it in a dishwasher. It doesn't say anything about hazards from consuming the stuff. Assuming that the Colgate-Palmolive company has a normal degree of concern for liability, I would conclude that it's not particularly dangerous to ingest it. Of course, that doesn't mean it wouldn't make you sick. --Anonymous, 23:26 UTC, April 9, 2010.

This that make you usually aren't very dangerous, since they don't stay in your system long enough to do much harm. --Tango (talk) 00:34, 10 April 2010 (UTC)

Permit me to add a Tangoese to English translation: "This that make you..." = "Things that make you sick...". :-) StuRat (talk) 00:52, 10 April 2010 (UTC)

In my experience adding dishwashing liquid has very amusing results--Jac16888^Talk 02:41, 10 April 2010 (UTC)

I was going to quibble with this by mentioning Mussolini's use of castor oil on his political enemies, but to my surprise the article notes that the victims "rarely died". 213.122.59.14 (talk) 07:43, 10 April 2010 (UTC)

Purified castor oil doesn't kill you -- it only makes you dirty your pants. The only dangerous toxin in castor beans is ricin, which is present in raw castor oil, but is removed during purification before the castor oil is marketed. 24.23.197.43 (talk) 02:15, 11 April 2010 (UTC)

I was about to jump in to this with a big NO when I saw the title on my watchlist...that had me alarmed for a moment. Anyway, if you want to be able to use a glass right away after washing it, the way we used to do that in boy scouts was washing in warm soapy water, then rinsing in bleach water, then in normal water...after drying with a cloth they were good to go. Ks0stm ^(T•C•G) 23:48, 9 April 2010 (UTC)

If you accidentally swallow a poison, the emergency procedure MAY (not always) be to vomit it up. One way to do this is to swallow a teaspoon of dish detergent with a glass of water, so I would say that it can make you vomit.24.150.18.30 (talk) 02:25, 10 April 2010 (UTC)

do bodybuilders get blind or have poor eyesight from overexertion?

This is not a request for medical advice, and I am not a bodybuilder, but my friend told me bodybuilders get blind at a very young age or at least get very poor eyesight due to overexertion. However I don't see the relationship - maybe if they take some kind of weird steroids that put their blood pressure through the roof or something, but just from "overexertion"? Is there anything to what my friend said? 82.113.121.93 (talk) 19:48, 9 April 2010 (UTC)

Sounds like an old wive's tale to me. Googling does not turn up anything compelling. --Mr.98 (talk) 21:44, 9 April 2010 (UTC)

The story I heard when I was younger was that straining to lift weights can put undue stress on capillaries, and those at the back of the eye are particularly fragile. Rupture of these capillaries could produce a bleed which disrupts the retina, resulting in partial or total blindness in the affected eye. I have no evidence that this is in fact the case. --TammyMoet (talk) 08:20, 10 April 2010 (UTC)

In the movie La Strada the strongman performer Zampanò warns onlookers that the feat he will attempt may go wrong and make him blind. Cuddlyable3 (talk) 11:42, 11 April 2010 (UTC)

Enzyme for digesting pork?

Yesterday someone told me they had been raised vegetarian and so had trouble digesting pork because they didn't produce a necessary digestive enzyme. What enzyme would that be? RJFJR (talk) 19:53, 9 April 2010 (UTC)

I've heard vegetarians claim this too, but this and this would both indicate that it's not true; that your body generates the requisite digestive enzymes regardless of your diet. In the unlikely case that your friend is a panda, she can still digest meat, but may have lost the taste for it. -- Finlay McWalter • Talk 20:06, 9 April 2010 (UTC)

The gut bacteria will be different. And it takes a while before you change the colony composition. So you need to change your diet slowly to let the bacteria adjust. Ariel. (talk) 20:23, 9 April 2010 (UTC)

Digestion of meat (protein) is mostly done by proteases in the stomach at low pH. Intestinal bacteria may play a secondary role, but it is a minor one. See Gut flora#Functions for a run-down of their major roles in the human digestive tract. These bacteria are more relevant to the digestion of carbohydrates, starches and to some extent even cellulose; but protein is pretty much chemically digested by gastric acid. Nimur (talk) 21:21, 9 April 2010 (UTC)

Gastric acid starts the process, but trypsin and other pancreatic proteases do the main job of digesting all proteins, either plant or animal source. Vegetarians can certainly digest pork: they just notice a change in stool appearance and composition related to a different set of undigestible excreta. alteripse (talk) 02:49, 10 April 2010 (UTC)

Baby teeth

Why do children lose their Deciduous teeth when growing up? Why is one set of teeth not enough for one's entire life? 71.178.44.93 (talk) 20:14, 9 April 2010 (UTC)

For one, it's a matter of scale. The original teeth are designed for a smaller mouth, and you need to grow additional teeth anyway to fill in the gaps with age. Historically, poor dental hygiene and unprocessed foods caused more wear and tear on teeth, so having the initial set swap out was also handy. This way you have small teeth when you can't fit more, and larger, stronger teeth to take over as the first set wear out and/or become too small. —ShadowRanger ^(talk|stalk) 20:24, 9 April 2010 (UTC)

I think the main issue is size. A child's mouth is much smaller than an adult, so the child's set of 20 mostly smaller teeth is replaced by the larger set of 32 adult teeth. It makes sense to have a smaller set of smaller teath for a smaller head. --Jayron32 20:31, 9 April 2010 (UTC)

I think it's important to remember that this did not evolve first with humans; it is a general mammal trait. Looking for an explanation that relies entirely on human experience is going to likely be incorrect. Generally speaking, the evolutionary question seems to be why don't mammals lose and replace their teeth more regularly, like most fish and reptiles. Retaining a permanent set of teeth is the special evolutionary development, not the loss of teeth. --Mr.98 (talk) 21:10, 9 April 2010 (UTC)

An equally valid question is why we don't replace any tooth which falls out due to decay or injury; this would be a great evolutionary advantage. It seems to be pretty unfortunate that we do not have this capability. See regeneration (biology) for some related processes. Nimur (talk) 21:24, 9 April 2010 (UTC)

Sometimes we do - my grandfather lost most of his adult teeth in his childhood due to malnutrition and grew a third set. It's unusual, though. --Tango (talk) 22:04, 9 April 2010 (UTC)

Wonder if this could be artificially stimulated, that would be nifty. 213.122.59.14 (talk) 07:46, 10 April 2010 (UTC)

Or more interestingly I wonder if any of your grandparents offspring inherited the trait. The embryo teeth would probably be visible by radiological examination. We could then start breeding a race of people with replaceable teeth! Caesar's Daddy (talk) 08:00, 10 April 2010 (UTC)

Some babies are born with a set of teeth; these fall out and are replaced during normal teething. As for why primates don't have continuously growing teeth - in rodents (which are reasonably close to primates) they do have this, but their teeth don't fit well together, which is OK for tearing your food, but not good for grinding it. CS Miller (talk) 10:36, 10 April 2010 (UTC)

In that case, wouldn't replacing all teeth but the molars (used for grinding) and maybe bicuspids, make sense ? StuRat (talk) 12:38, 10 April 2010 (UTC)

Rodents' teeth aren't replaced, they just grow continuously. That's why you have to give pet rodents something to gnaw on so they can wear their teeth down. --Tango (talk) 14:38, 10 April 2010 (UTC)

That would be interesting to know, but (un)fortunately my Grandad managed to pull himself out of poverty, so none of his children or grandchildren (or great-grandchildren, although they're all still on baby teeth, I think) have been malnourished (also, the welfare state arrived, so they wouldn't have been anyway). --Tango (talk) 14:38, 10 April 2010 (UTC)

From a completely individualized, non-evolutionistic perspective, one would lose his or her baby teeth because the adult teeth exist deeper in the bone and being erupting into the space occupied by the baby teeth's roots. The baby teeth roots resorb under the pressure (this can perhaps be referred to as pressure necrosis) and without proper support from the surrounding bone (as the roots are all but gone after said resorption), the baby tooth crowns either fall out or are pulled out by children, parents, dentists, etc. When people have congenitally missing succedaneous (adult, in that they succeed the baby teeth) teeth, they will very likely retain their baby teeth well into adulthood, if not retain them for life. I've treated 35-year-olds with baby maxillary lateral incisors and canines because they never had the adult teeth to cause them to fall out. DRosenbach ^{(Talk | Contribs)} 02:28, 11 April 2010 (UTC)

bride selection

In the movie, "Mongol" about the creation of Genghis Khan the Mongols are depicted as following the custom of an 8 or 9 year old son of a Khan (no pun intended) selecting his bride from girls near his own age. Was this custom for everyone or just the Khan's son and in either case what other cultures have this custom and does it exist in other societies like those religious groups that live in Montana or anywhere else? 71.100.3.207 (talk) 23:47, 9 April 2010 (UTC)

If by "Those religious groups that live in Montana" you mean the Mormons (who actually are headquartered in Utah), then no, they do not practice that nowadays, although I don't know if they did in the past. Ks0stm ^(T•C•G) 23:52, 9 April 2010 (UTC)

There is a small fringe group of the Mormon church, the Fundamentalist Church of Jesus Christ of Latter Day Saints, or FLDS church, which still practices both polygamy and childhood betrothal. They kidna flew under the radar until a few years ago, during the Raid on the YFZ Ranch. However, this group does not represent a significant part of the Morman church. The vast majority of LDS church members have family practices which generally fall into the norm of Western cultural expectations. --Jayron32 04:55, 10 April 2010 (UTC)

In Arab countries, it's pretty darn common for girls to be given in marriage (without any semblance of consent) at a very young age, often as young as 6 years. In what is possibly the most notorious example of this barbaric practice, Muhammed married his wife Aisha when she was six years old, and screwed her for the first time when she was ONLY NINE. (Some prophet!) 24.23.197.43 (talk) 05:48, 10 April 2010 (UTC)

Child marriages were common in a number of cultures. BTW 'prophet' simply means messenger of God. Given that in Abrahamic religions, be it Judaism, Christianity or Islam, God was guilty of genocide, biological warfare, terrorism and numerous other things and directly advocated a father murder his child we perhaps should be surprised with whatever evils his messengers may or may not have commited. It's perhaps also worthwhile remembering that whatever we may think of historic practices, they were often quite different from what we regard as morally acceptable nowadays. After all Mary the allegedly virgin mother to God was bethored to Joseph at sometime between 12 or 14 [19] [20], the norm at the time [21]. Nil Einne (talk) 16:42, 10 April 2010 (UTC)

14 years old is, physiologically speaking, not too young to marry (though right on the borderline) -- 9 or 10 years old certainly is. And what makes you think that marriage before puberty can ever be acceptable in any historical context? 24.23.197.43 (talk) 01:55, 11 April 2010 (UTC)

"Given that in Abrahamic religions, be it Judaism, Christianity or Islam, God was guilty of genocide, biological warfare, terrorism and numerous other things and directly advocated a father murder his child we perhaps should be surprised with whatever evils his messengers may or may not have commited." -- Your take on the binding of Isaac is completely bassackwards vs. what is actually said to have happened -- in the Biblical story (Genesis 22:1-20), it's made clear that God had only commanded Abraham to sacrifice Isaac to test his faith, and then expressly commanded Abraham not to do it. In fact, these verses are in themselves the first of God's commandments to be revealed to mankind -- a commandment to not sacrifice humans to God. And as for "whatever evils [God's] messengers may have committed": you haven't provided one single shred of evidence that any of God's messengers other than Muhammad had actually committed any evil acts, so until and unless you do, this claim of yours is absolutely baseless. And since in an earlier thread I have provided, at your request, evidence that "stealth jihad" is indeed happening in some parts of the USA, I likewise challenge you to provide evidence that Moses or Jesus have committed evil, or else to take back your claim that they ever did so. 24.23.197.43 (talk) 04:17, 11 April 2010 (UTC)

I meant to return sooner an move this to the humanities section where I intended to put it in the first place but its really great to know the science section is so well monitored by those who are at least knowledgeable of the Faith. Anyway, The way the marriage selection is depicted in the movie is quite attractive to me. One year older girl asks Son of Khan to pick her and stops father from taking him to another camp to select a bride and selects her instead. Hot stuff. They had to wait five years and ended up waiting even longer. As for the Mormons marrying young girls to old men that is a different story. Its not hot but disgusting and should be outlawed secularly and in the Mormon Church. actually I was thinking about another group that moved from Switzerland. Is there a list of religions which practice same age youthful commitments? 71.100.3.207 (talk) 06:27, 11 April 2010 (UTC)

April 10

Flower unknown

What flower is this? --Tyw7  (Talk • Contributions)   Changing the world one edit at a time! 00:08, 10 April 2010 (UTC)

Well, it looks to me like the picture title is correct in calling them Bluebells. To my eye they look very similar to the picture in the Hyacinthoides article. Looie496 (talk) 05:14, 10 April 2010 (UTC)

onion skin layers

Is the core of the melted or even the solid part of the Earth's core layered somewhat like an onion with heavier elements occupying deeper layers and if so could layers consisting of radioactive isotopes release massive amount of energy from decay or fission in instances of mass beyond the critical mass so as to be responsible for the giant blob of lava that surfaced beneath Siberia 250 million years ago and destroyed the atmosphere and made most things go extinct? 71.100.3.207 (talk) 00:35, 10 April 2010 (UTC)

No. It gets continually mixed up by thermal convection, so radioactive isotopes never get nearly that concentrated. Thermal convection also occasionally brings up hot magma to near the surface, causing volcanism of various degrees. StuRat (talk) 00:41, 10 April 2010 (UTC)

The georeactor hypothesis posits that there is such a natural fission reactor of concentrated heavy elements in the core of the Earth. This is generally considered unlikely by nearly all Earth scientists. Dragons flight (talk) 03:11, 10 April 2010 (UTC)

However, the Earth's crust does have layers that are not necessarily organized by mass, see stratum. ~AH1^(TCU) 03:18, 10 April 2010 (UTC)

Hijacking the question somewhat, does this extinction event have an article? Vimescarrot (talk) 08:53, 10 April 2010 (UTC)

http://en.wikipedia.org/wiki/Siberian_Traps. —Preceding unsigned comment added by 66.133.196.152 (talk) 09:11, 10 April 2010 (UTC)

Thanks. Vimescarrot (talk) 11:43, 10 April 2010 (UTC)

Note that forming a critical mass is difficult even under ideal conditions. Mixing up even just pure amounts of uranium ore will not result in an explosion, ever. There are, however, evidence of localized natural nuclear fission reactors—see Oklo. But they could not explode. --Mr.98 (talk) 14:40, 10 April 2010 (UTC)

Food additives

Why do they add so many artificial chemicals to food? If you look at a food label, often up to half of the ingredients (sometimes even more) will be things with long chemical names which are mostly incomprehensible to anyone without serious chemistry background. Why can't they just stop using them, instead using only the real, natural ingredients? --70.129.184.122 (talk) 00:51, 10 April 2010 (UTC)

They can, and some companies do, like Breyer's Ice Cream. However, most consumers don't seem to care, so most companies don't care, either. Also note that some of those "long chemical names" are just vitamins and such, but a few really are as nasty as they sound. StuRat (talk) 00:57, 10 April 2010 (UTC)

You're wrong that they don't care. It's just that, for obvious reasons, the price is much lower when more than half of your concoction is industrially produced chemistry sourced from giant vats rather than hard to harvest individual pieces of whatever. So it's just that some people care more about the price. 82.113.121.36 (talk) 02:39, 10 April 2010 (UTC)

What are "real, natural ingredients"? With the exception of some raw fruits and vegetables, we rarely eat things in their natural form. Many things are cooked which alters its chemistry, dramatically in some cases. Items like sugar and wheat flour are highly processed derivatives used in forms that have few similarities to the plants they came from. Many of the complicated chemical-sounding ingredients are like sugar and flour in that they are highly processed food derivatives. Others, like the baking soda used in much baking, are generally created in chemical vats because is is cheaper and more uniform to produce it that way than to extract it from natural analogs. Highly processed ingredients have advantages for bulk food manufacturers because using these ingredients provide more uniformity and avoid variations that can occur with natural products like fruits and vegetables. In many cases the processing also kills or removes potential pathogens like bacteria that may hide in unprocessed foods. Often highly processed foods last longer, can be produced in greater quantities, and are less likely to spread disease than traditional foods (though in some cases the ingredients are later found to have other problems like causing cancer or affecting hormone levels). On the other hand processing also runs the risk of excluding natural substances present in raw foods whose value may not have been recognized. And of course, many people seem to feel natural foods taste better, even though many of the additives are also there in attempts to affect taste or texture. Dragons flight (talk) 03:08, 10 April 2010 (UTC)

The original poster didn't give any reason why companies would want to make such a change. Every ingredient in a product is there for a reason -- it contributes to the flavor or the color or the texture or it improves the shelf life or whatever. --Anonymous, 03:05 UTC, April 10, 2010.

See also trans fat, sodium benzoate and monosodium glutamate. ~AH1^(TCU) 03:15, 10 April 2010 (UTC)

To answer the original OP's question without perjorative, the reasons why chemical additives are added to foods are many. If we isolate them into types of additives, you can get the following sorts of categories:

• Chemically identical, but manufactured versions of, natural compounds (generally things like artificial flavors and vitamins and things like that)
• Completely unnatural additives which improve the appearance or texture or flavor of food (things like emuslifiers, artificial colors, artificial sweeteners etc. etc.)
• Compounds designed to preserve shelf life of foods.

That's probably covers most of the bases. The first category is there for two purposes. Making flavors in a giant vat is cheaper than extracting the same flavors from natural sources. And vitamins are often added back into heavily processed foods because the processing tends to remove them. For example, white bread is enriched because the germ and bran contain most of the vitamins in grain. Low-fat milk (but not whole) has added Vitamin A, because vitamin A is fat soluble, and in removing the fat, lots of vitamin A is removed, so it has to be added back. The second category covers making food look or taste more appealing. Cheerios are kinda boring looking, but man the kiddies really prefer the Froot Loops with all of those wild colors. The third category is probably the most important. Ever buy a loaf of fresh made bread? It goes green in about 4 days, and that's in the winter. On a humid summer day, you're lucky to keep it until tomorrow. Ever wonder why bakeries practically give away "day old" bread for free? Cuz in another day or two it starts to go. Now, ever wonder why factory-made bread can keep for like 2 weeks? Most of those unpronouncable chemicals are why. So, if you will go through a loaf of bread in a day or two, the fresh bread is fine. But if you are like most families, and your gonna make like 2 sandwiches a day with it, then having a loaf go bad a few days after you buy it is wasteful and inconvenient. Not saying these are all good reasons to have all of these chemicals, but they are the reasons nonetheless. --Jayron32 04:50, 10 April 2010 (UTC)

I feel that I should point out that natural does not necessarily equal good, and unnatural does not necessarily equal bad. Most crop plants have been artificially selected for all sorts of traits, which is a good thing, because most of the time it is not to a plant's advantage to be eaten (excepting certain kinds of fruit), therefore many plants tend to be poisonous, distasteful, or nutritionally poor in their "natural" forms - would you like to eat natural maize? (the one on the left). What I do agree with is that companies don't always make it clear what the food additives they are using actually are - which is a problem, since some are very bad for you (trans fats), whereas some are actually good for you (E300, aka vitamin C). 131.111.185.75 (talk) 09:04, 10 April 2010 (UTC)

The natural maize on the left in the pic just looks like it hasn't grown any corn, yet. StuRat (talk) 12:24, 10 April 2010 (UTC)

Does that mean you'd like to eat it? Do note that that's about as good as it gets. It doesn't 'grow' any 'corn' Nil Einne (talk) 15:59, 10 April 2010 (UTC)

Isn't the corn the seed ? How can it reproduce if it doesn't grow any seed ? StuRat (talk) 16:37, 10 April 2010 (UTC)

What do you mean? That is the seed you're seeing. Haven't you ever seen grass seed before? Edit: Perhaps [22] & [23] will help Nil Einne (talk) 16:44, 10 April 2010 (UTC)

The middle pic seemed to show both corn and the green things, which I took to be what grows into the corn. So, you're saying that the left pic is fully fertile even without growing any corn ? Ok, I see. StuRat (talk) 17:15, 10 April 2010 (UTC)

Urgh. Stu, just see Teosinte, which is the wild ancestor of Maize. The entire fruiting portion of the teosinte plant is about a centimeter in size, while you know how big an ear of corn is. The point is that, through hundreds of years of selective breeding, mesoamerican farmers were able to produce modern Maize from Teosinte. They are the same species of plant, but careful breeding (i.e. unnatural processes) created the modern food plant. Maize may itself be one of the most important food crops in all of history, and if we asked for people to live solely on "natural" or "wild" foods, i.e. taking the natural foods movement ad absurdum to its ultimate conclusion, it seems fair to say that the entirety of civilization could not survive. That is the point of what is being said above. --Jayron32 18:48, 10 April 2010 (UTC)

I don't know how you would separate natural selection from artificial, in the case of early humans. If they ate the better food, and their feces thus contained seeds that grew more of that food, and it therefore spread, is that natural or artificial ? StuRat (talk) 21:04, 10 April 2010 (UTC)

That isn't how teosinte became maize. It was selectively bred by deliberate human intention. The same way that a wolf became a chihuahua. That's the point. Neoluddites who don't want anything "artificial" or "manmade" in their food should keep in mind that almost nothing we eat isn't manmade; that all of our food exists because humans deliberately made it that way; there's almost nothing in the Western diet which is "natural". --Jayron32 03:56, 11 April 2010 (UTC)

Paddle is moving and stationary at the same time: parallel universes????

What would the paddle look like when it is "moving and stationary at the same time?" What is the upper limit on mass or size for this claimed effect to apply? [24]. Edison (talk) 02:19, 10 April 2010 (UTC)

You might want to read this. The actual paper is here. Not having read it yet, I gather they put a fairly large object into a superposition of the ground state and the first excited vibrational state. I don't know what's new or interesting about that. I thought phonons in solids were old hat. -- BenRG (talk) 04:37, 10 April 2010 (UTC)

"Here we use conventional cryogenic refrigeration to cool a mechanical mode to its quantum ground state. We achieve this by using a micromechanical resonator with an isolated mechanical mode near 6 GHz, which we term a microwave-frequency 'quantum drum', whose ground state is reached for temperatures below ~0.1 K." So they cooled a tiny object below 0.1 K, which because of its special resonant properties happens to leave it in the ground state with high probability. Meh. More interesting is that they can transfer the vibrational states to and from a separate qubit (|ground〉 ↔ |0〉 and |first-excited〉 ↔ |1〉, or something like that), and do measurements on the qubit. So I guess they are actually measuring the superposition state—they're not just doing an energy measurement and then claiming for no good reason that the system was in an energy superposition before the measurement, as I had cynically assumed.

Anyway, it looks like an interesting paper but it has approximately nothing to do with that Fox News article. There's no theoretical size/mass limit for this kind of thing—any object left in a perfect vacuum for long enough will eventually radiate all its energy and end up in a ground state—but practically speaking you're limited by refrigeration technology, about which I know very little. These low-energy vibrational modes are basically Fourier modes, and superposition is basically... superposition. If you decompose a wave in a solid into Fourier components and it's a sum of more than one, that's a superposition of those modes. Your intuition from classical wave mechanics won't lead you too far astray here. What makes this system interesting is that it's almost not in a superposition of energy modes. -- BenRG (talk) 08:34, 10 April 2010 (UTC)

If the object is in superposition - and you "observe" it - doesn't it just collapse into either one or the other state? If so, then the answer to the first part of the OP's question ("What would the paddle look like...?") is that it will appear to (boringly) either vibrate or not vibrate. Schrödinger's cat explains this. The whole point of the cat thought-experiment is that there is no upper size limit on this kind of thing - and the argument that the (typically sensationalist) FoxNews article makes for this being a proof of the parallel worlds hypothesis is that the entire universe is in superposition as a result of this. If you accept that interpretation (and it seems like the best choice to me, personally) - then this isn't really big news. There are many interpretations of the 'meaning' of superposition - this experiment doesn't 'prove' any one or another - so the Copenhagen interpretation could still be the correct one. So (surprise, surprise), the FoxNews article is incorrect. SteveBaker (talk) 12:26, 10 April 2010 (UTC)

"They report, we decide." Thanks. Edison (talk) 12:51, 10 April 2010 (UTC)

For some strange reason, macroscopic superpositions in momentum space are not considered to be interesting Count Iblis (talk) 21:15, 10 April 2010 (UTC)

Brain simulations

Does Henry Markram publish his source code (not that I could run it)? If so, where? I think I once saw an (open source maybe?) project that tries to simulate a single neuron. Can anyone point me to that? 74.14.108.102 (talk) 04:34, 10 April 2010 (UTC)

Source code for what project? He's been involved in a bunch of things. And there have been literally thousands of projects simulating single neurons, with dozens at least based on open source code. The NEURON simulator developed by Michael Hines is one of the most widely used; see the NEURON site for more info. If that doesn't meet your needs, you'll probably have to be a little more specific about what you want to do in order to get a more useful answer. Regards, Looie496 (talk) 05:02, 10 April 2010 (UTC)

Thanks for the link. As for Henry Markram, i guess I would be interested in anything he does, but the Blue Brain Project (an article which I now see mentions the NEURON simulator) is the one I've heard of. 70.26.154.114 (talk) 19:01, 10 April 2010 (UTC)

Chrome plating

what type of metel is used under the Chrome plating for bathroom faucets? is it nickel? if so wouldent deep scratches or pits expose the nickel and cause dermatitis? —Preceding unsigned comment added by Jonny12350 (talk • contribs) 04:38, 10 April 2010 (UTC)

What makes you think metallic nickel causes dermatitis? You've prob'ly shaved with nickel-plated razors on a regular basis (either your face, or your legs and armpits, depending on your gender -- though based on your user name, I think you prob'ly shave your face rather than your legs). Anyway, in both these cases, the skin comes into direct contact with the nickel plating on the blade, and in most people it doesn't cause any problems (or else they would've had to stop using nickel plating for the razor blades). 24.23.197.43 (talk) 06:04, 10 April 2010 (UTC)

Just checked out the nickel article -- it says that only those people who happen to have sensitivity to nickel can develop dermatitis from it (and that's only a small percentage of the population). The vast majority (including me) have no problems whatsoever with nickel. 24.23.197.43 (talk) 06:10, 10 April 2010 (UTC)

In some cases, or course, "Chrome plating" is real chrome, also a possible cause of allergic reactions, but when it is nickel (often satin or brushed), it is no more dangerous than handling cupro-nickel coins. People who have a serious allergy to nickel should probably choose an alternative finish - perhaps gold? Dbfirs 06:34, 10 April 2010 (UTC)

In most cases copper is used as a intermediat layer before the chromium is plated onto the material. Nickel is also used sometime. The direct deposition on bras seems not to work properly. Your kitchen wear, cutlery, pots and pans made from stainless steel are 8 to 10% nickel. You touch it every day and you have no problem with it so you will have no problem with your bathroom faucets. One point were it is different is with cheap jewlery or rivets in jeans, these materials are normaly plated with gold, chromium or other metals and there nickel is used as intermediat layer. This stuff is in contact with your skin for hours and with a little bit of sweat nickel can be set free and cause problems.--Stone (talk) 08:40, 10 April 2010 (UTC)

Now I have an image of a pointy, chrome-plated bra; makes me think of Wagner operas with fat women. StuRat (talk) 12:18, 10 April 2010 (UTC)

Atkins diet for small children

I was surprised when, years ago, I learned that the average adult human and late adolescent can subsist quite well on few to no carbohydrates. Does this extend to small children (disclaimer: I am not seeking advice on putting a small child on a diet). From a physiological perspective, do small children, babies or pregnant women have any nutritional need for carbohydrates that can not, in a healthy manner, be fulfilled by converting fat and protein? Thanks. Someguy1221 (talk) 06:26, 10 April 2010 (UTC)

Being a long-term dieter (now retired), I can say with some certainty that every diet has included a requirement for a multi-vitamin tablet daily, even the Atkins diet required this. As an example, a high-fat diet would not supply any vitamin C, which is vital to consume as the human body doesn't manufacture it. So if adults need nutrients which are not available on a low-carb diet, then it would make sense that all humans would, and especially those in the groups you mention. --TammyMoet (talk) 08:15, 10 April 2010 (UTC)

You really shouldn't put small children on any kind of a diet without consulting a doctor...especially a radical diet like Atkins. You can do great harm (including long-term harm) by screwing with a childs' nutrition. SteveBaker (talk) 12:06, 10 April 2010 (UTC)

See ketogenic diet. A no carb diet can be done carefully for certain serious disorders (usually intractable seizures), but growth needs to be monitored. The purpose of a no-carb diet is to turn off insulin, but remember that for children insulin is a growth hormone. Extremely low insulin levels for prolonged periods during the adolescent growth spurt can blunt growth and cost height. alteripse (talk) 14:26, 10 April 2010 (UTC)

Unknown Caterpillars

Are these Ochrogaster lunifer?

Hi there, I added a pic to Ochrogaster_lunifer of the cluster of Caterpillars. I'm now having doubts about the correctness of my identification as the pic I took seems to show blacker Caterpillars than the other pics in the article. This was near the Porongorup National Park, in the south west of Western Australia. Any thoughts? Thanks. SeanMack (talk) 10:41, 10 April 2010 (UTC)

A Google images search on "Ochrogaster lunifer" turned up pictures of both the very light colored and almost-black colored caterpillars...so on that (somewhat 'iffy') evidence, I'd suspect your photos are OK. On the other hand, this website says that the adult moths come in more than one color and says that "...the variety of colour forms suggests that there may be more than one species present in Australia." - and I suppose that this variation could easily extend to the caterpillars too. It links to this abstract on interscience which is highly relevant to this question. I would say, based on that article, that Ochrogaster lunifer should really be two separate species - which are presently mis-characterized as one. But one paper may not be enough to cause a re-characterization - and that makes it hard to know what to say in the Wikipedia article. I strongly suggest you take this discussion to the Talk: page for the Wikipedia article. SteveBaker (talk) 12:02, 10 April 2010 (UTC)

Bird deads, causes unknown

Hi all,

I'm in Brampton, Ontario, and three birds have died with no visible cause of death. On Thursday morning, we found a North American Robin in the backyard, and this morning, a male and a female yellow-bellied sapsucker in our driveway, literally lined up next to each other.

• there's no mosquitoes at all, so it's not West Nile,
• it likely wasn't a bird of prey or cat, there's no visible signs of trauma, and the spines seem solid, not cracked,
• all were found far enough away from windows, that it's unlikely that they hit.

I've contacted the Ontario Ministry of Environment, via email, to see if they're concerned. What would it be? There's always the option of a neighbour setting out poison, but is there anything else? -- Zanimum (talk) 13:00, 10 April 2010 (UTC)

Bird flu ? StuRat (talk) 13:06, 10 April 2010 (UTC)

That's what we're worried of, but there's no reports yet in Canada. -- Zanimum (talk) 14:18, 10 April 2010 (UTC)

I've heard of birds and other animals eating fermented fruit and dying as a result of the intoxication. Beach drifter (talk) 13:38, 10 April 2010 (UTC)

Would this include fruit in open compost containers. Our are closed, but others might have open ones. While we've had above seasonal temperatures in the area, we're back down to just above freezing, no fruits are in season -- the buds haven't even opened yet. Only parsnips could be in the ground currently. -- Zanimum (talk) 14:18, 10 April 2010 (UTC)

I would say that intoxication is an unlikely explanation. Diseases are easily spread between birds, and some are fatal (to birds, not to humans). Your suggestion of carelessness with rat poison seems a possibility. Dbfirs 19:38, 10 April 2010 (UTC)

We cannot provide epidemiological or public health advice, naturally. A die off like you describe is what we saw when West Nile came though, although you claim "no mosquitoes." It sounds abnormal for that many birds in a small area to be found dead without physical trauma, and you might wish to contact the local health department in addition to the environmental folks you already emailed. The dead birds might be a hazard if handled if they have disease. If they ate or drank something toxic or poison, they might be a hazard to pets who find them. Edison (talk) 19:45, 10 April 2010 (UTC)

Or maybe there's a gas leak nearby ? Birds seem to be a lot more sensitive to that than us. StuRat (talk) 20:59, 10 April 2010 (UTC)

Which is why miners use canaries to detect methane. 24.23.197.43 (talk) 02:07, 11 April 2010 (UTC)

There goes my theory that they were used to add accent colors to those drab old mines. :-) StuRat (talk) 03:49, 11 April 2010 (UTC)

Where I live there is a department of health (or something like that) which actively solicits reports of dead birds of unknown cause (they are monitoring for bird flu). Perhaps there is a comparable agency where you live. Also check with your local university. Ariel. (talk) 06:37, 11 April 2010 (UTC)

How power stations deliver electrical energy to my home

I'm trying to understand live and neutral and how power is transmitted. I recall once reading that overhead powerlines are all live, by which I intend to say that they are all pushing and pull current in union, and no voltage difference occurs between them, and that the return occurred via the earth. Is that correct? Does this mean that all power stations which are connected into a single grid need to be in phase? Otherwise, one power station in location A, 100 km from a power station in location B could be pushing current through earth while that in location B is pulling current and that would have implications unfathomable to the human mind. The neutral in my domestic power supply... is it connected to earth and if so, where? --84.13.85.158 (talk) 15:48, 10 April 2010 (UTC)

The three phases are 120 degrees out of phase, so, on average, they cancel out. In practice, this seldom happens exactly, so there is often but not always a small neutral or common return wire as well. The supply voltage is between the conductors on a three-phase supply (large overhead powerlines), but this means that they are all at different voltages to earth at any one instant. Yes, it is essential that any generator is in phase before it is connected to the grid, though it would soon be forced into phase by very large currents if it wasn't! The neutral at your house is created at the last step-down transformer by bonding one side of the output winding to earth, and this earth bonding is usually repeated at your house (depending on where you live). See Three phase electric power for details. Dbfirs 15:55, 10 April 2010 (UTC)

Note that many long-distance power lines are carrying high-voltage direct current, with AC conversion closer to the consumers (regional systems but not the "last mile"). For example, the UK-to-France grid connection is DC. Here's a link to the history of DC links [25]. NVO (talk) 16:12, 10 April 2010 (UTC)

As to your question of "how they keep the phase locked" ... we have <quite sketchy> articles on Wide area synchronous grids and the Synchroscope, the antique device that still works ... NVO (talk) 16:24, 10 April 2010 (UTC)

I think the DC lines are quite rare and used only for long-distance transfer of power, not for distribution. See our article on High voltage direct current.
On synchronisation, I think that keeping in phase is almost automatic as long as the generator is running properly because if it lags behind it will become an electric motor, drawing power from the grid (and possibly being damaged if it lags too far). Obviously it is essential for the frequency and phase to be synchronised before connection. I assume that there is an automatic disconnection if something goes wrong. Our article might be improved by explaining this. Have we any electrical engineers? Dbfirs 16:32, 10 April 2010 (UTC)

A picture (or in this case a meter) paints a thousand words.[26]--Aspro (talk) 18:12, 10 April 2010 (UTC)

That's brilliant! Smart devices to switch off the load at high demand must make life much easier for the grid engineers. Was I correct in assuming that individual generators are automatically synchronised by the grid once they are connected? I know that mains electric clocks are less common these days, but do the engineers still ensure that the time-average frequency is exactly 50 Hz? Dbfirs 19:01, 10 April 2010 (UTC)

Yes. Pieter-Tjerk de Boer's web page answers your next question better than I can. As the grids got bigger and bigger extra refinements were built in to the system though. Maybe the following link could be added to the appropriate article, because it goes into some detail of the European system but I can’t find the time right now. Load-Frequency Control and Performance Policy--Aspro (talk) 20:42, 10 April 2010 (UTC)

Thanks for the interesting links. Dbfirs 07:36, 11 April 2010 (UTC)

nuclear waste

Is it possible to drill a hole deep enough to use the Mantle as a place to dispose of nuclear waste? 71.100.3.207 (talk) 16:08, 10 April 2010 (UTC)

You might be interested to read our article on Mantle_(geology), especially the exploration paragraph, but I will leave it to an expert to comment on the practicalities of putting nuclear waste down there. Dbfirs 16:19, 10 April 2010 (UTC)

Bad idea. The pressure down there would cause the nuclear waste to erupt back up. StuRat (talk) 16:28, 10 April 2010 (UTC)

Yes, I was worried about that, but how do they avoid creating a volcano when they explore the mantle? Dbfirs 16:46, 10 April 2010 (UTC)

We don't explore the mantle, at least not by drilling holes into it. StuRat (talk) 17:11, 10 April 2010 (UTC)

When drilling very deep wells (typically looking for petroleum), most of the pressure at depth is kept at equilibrium by the hydrostatic head. In other words, your bore hole is full of fluid - drilling mud. That fluid has weight (a lot of weight, if you're drilling 20,000 feet). The effect is a very high pressure that counteracts most of the pressure at depth. However, because of geology and geochemistry, it is possible to drill into a region where the pressure is higher than hydrostatic equilibrium. This often happens as pressure builds up over time, usually by the physical and/or chemical release of gas or fluids from rock pore spaces, or thermal contact which changes the equilibrium pressure. If the reservoir is sealed, the pressure is much higher than it "should" be, and drilling through the seal rock releases it geyser-style. (This is what you see in stereotypical oil spout photographs, and is a sign of poor drilling engineering. To fix and/or preempt this sort of problem, deep wells have one or more well completions, including well casing and downhole pressure valves. Schlumberger has a very nice website, the Oilfield Glossary, which explains terms like well completion with links, diagrams, and up-to-date state-of-the-art drilling industry expertise. As you can see, no techology exists which can effectively drill all the way down to the mantle of the Earth; very deep offshore wells are now pushing close to the 10-km neighborhood below sea-level, but this is not anywhere near reaching the mantle. To prevent a "volcano", we would need to invent the technology to both drill and complete a well at much greater depths; this would require materials that could withstand much greater temperatures and pressures than we currently have. Nimur (talk) 19:35, 10 April 2010 (UTC)

We can't even get through the Earth's Crust, let alone get into the Mantle. The continental crust is approximately 20-30km thick and our deepest mines are at most 5km down (I think). That means it's going to be very, very difficult to get to the Mantle any time soon. Regards, --—Cyclonenim | Chat  17:35, 10 April 2010 (UTC)

... so is the article to which I linked (Mantle_(geology)) total fiction? Dbfirs 18:52, 10 April 2010 (UTC)

No. We know quite a lot about the mantle, just not from direct observation. Measuring how Earthquakes travel around the world is the main way of finding out about the Earth's interior composition, I think. --Tango (talk) 18:57, 10 April 2010 (UTC)

Yes, I know that, but the article talks about drilling 23,000 feet to the mantle below the ocean floor. Was this done? Dbfirs 19:05, 10 April 2010 (UTC)

This book:
Ojovan M.I., Gibb F.G.F. "Exploring the Earth’s Crust and Mantle Using Self-Descending, Radiation-Heated, Probes and Acoustic Emission Monitoring". Chapter 7. In: Nuclear Waste Research: Siting, Technology and Treatment, ISBN 978-1-60456-184-5, Editor: Arnold P. Lattefer, [[Nova Science Publishers|Nova Science Publishers, Inc.
seems to suggest that the possibility is being seriously considered. Dbfirs 19:53, 10 April 2010 (UTC)

See: Kola Superdeep Borehole, they went down to 40,000 feet (on land) and it remains the deepest that mankind has ever drilled. SteveBaker (talk) 20:01, 10 April 2010 (UTC)

That project was abandoned because of the high temps at the bottom, and that only went about a third of the way through the crust. StuRat (talk) 20:56, 10 April 2010 (UTC)

23,000 feet = 7km or there about, not far above what I said. 40,000 is admittedly quite a bit more but still 8km or so from the mantle. So no, we can't store nuclear waste there. Regards, --—Cyclonenim | Chat  22:30, 10 April 2010 (UTC)

... yet! (... though I agree that we are not likely to try it until we know a lot more about the risks.)
What about the self-boring module that melts its way through the crust? Has this ever been built?
If our article on Chikyu Hakken is correct, and they are still on schedule, they should be nearing the mantle soon. Dbfirs 06:44, 11 April 2010 (UTC)

Well of course there is always a "yet" you can add on to any hypothetical situation. We can't travel to other galaxies... yet. Doesn't mean it's realistic to assume we have even the potential to do it yet. I imagine getting through the crust would be very, very expensive indeed and I'd speculate that it's probably cheaper to send it into space, where it won't come back or have any real consequences (as long as it clears the orbit intact). Regards, --—Cyclonenim | Chat  08:03, 11 April 2010 (UTC)

OK, fair comment. So our articles are over-optimistic about direct exploration, and all attempts have failed? Dbfirs 12:22, 11 April 2010 (UTC)

Have there even been attempts to get to the mantle? As far as I'm aware the only projects have been to see just how far we can get, and ultimately it's not that far. There was no failure, per se, just not as far as you thought :) Regards, --—Cyclonenim | Chat  14:25, 11 April 2010 (UTC)

Yes, I assume that this was an attempt: "The 57,500-ton Chikyu, which means the Earth in Japanese, is scheduled to embark in September 2007 on a voyage to collect the first samples of the Earth's mantle in human history." (from refernce 22 in our article on Mantle_(geology)). Since no-one seems to have heard of any success, I assume that the attempt was either a failure or was abandoned. Dbfirs 16:47, 11 April 2010 (UTC)

... and everyone seems to assume that the crust is of uniform thickness. The following is from ref. 21 in the same article: "Scientists have discovered a large area thousands of square kilometres in extent in the middle of the Atlantic where the Earth’s crust appears to be missing. Instead, the mantle - the deep interior of the Earth, normally covered by crust many kilometres thick - is exposed on the seafloor, 3000m below the surface." Dbfirs 16:54, 11 April 2010 (UTC)

Nuclear waste - reuse

Why can't we just centrifuge it again to re-enrich it to the point that it's ready for manufacturing of new fuel rods? According to [27], naturally occurring uranium is 0.72% U-235. What about the waste? Much less? --84.13.85.158 (talk) 16:32, 10 April 2010 (UTC)

You can reprocess the spent fuel rods, nuclear reprocessing goes into the details although the article seems to have problems. However you still end up with a lot of nuclear waste which includes a lot of stuff besides the spent fuel rods. Interesting enough this [28] & [29] suggest reprocessing actually results in more waste although I don't know how much you can trust the Institute for Energy and Environmental Research who are apparently anti-nuclear. However you could probably research it yourself from the citations they use Nil Einne (talk) 17:00, 10 April 2010 (UTC)

I haven't read the linked articles, but there are two factors to consider when measuring how much waste is produced by reprocessing. 1) You need to compare the waste produced by reprocessing with the waste that would be produced by using new fuel instead, you can't just look at the absolute amount produced. 2) There is a big difference between low level waste and high level waste - you can't just look at the total amount of waste produced, you need to look at how radioactive it is. --Tango (talk) 19:02, 10 April 2010 (UTC)

Actually the problem with an increased level of high level waste seems to be a key concern. E.g.:

Reprocessing is also the option that generates the largest amount of radioactive waste. The most dangerous of this waste is called high-level waste -- a liquid waste stream carrying chemicals used in reprocessing along with many radioactive isotopes from the spent fuel or other material. This high-level waste would be added to over 30 million gallons of liquid waste from past reprocessing already stored in underground tanks at SRS. (first ref)

When high-level waste and Greater than Class C waste are considered together, the volume of waste to be disposed of in a repository is greater by about six times compared to the no-reprocessing approach that is current U.S. policy on a life-cycle basis. Low-level waste and waste shipments are also increased several fold by reprocessing. These are Department of Energy estimates comparing present U.S. once-through policy with the French “recycling” system using thermal reactors (second ref)

Nil Einne (talk) 00:33, 11 April 2010 (UTC)

300 million gallons sounds dramatic - but it's a volume of only 100 x 100 x 100 meters. That's quite manageable. The problem with unreprocessed fuel rods is that they have long half-life materials. Reprocessing extracts those and leaves materials with a more manageable half-life behind. SteveBaker (talk) 02:02, 11 April 2010 (UTC)

There was an NPR radio piece about this just a few days ago. You can indeed reprocess spent fuel rods - extract usable (high-radiation) stuff to use as fuel - and wind up with less bulky, less radioactive waste. That seems like a win/win situation - and indeed this is what is done in the UK, France and a few other countries. However, in the USA, the cost of reprocessing is still higher than storing the waste (for a million years!) and mining new uranium - so it's not done here. Elsewhere in the world, there is concern that reprocessing uranium-fuel-waste produces plutonium waste - which useful for making nuclear weapons. Hence there has been pressure on certain countries to send spend fuel rods to places like Europe for reprocessing instead of having them do it in-house and (like India) winding up with weapons' grade plutonium.

An interesting fact from the NPR piece is that if you took all of the used fuel rods ever produced throughout the USA over all of history - you could keep them in one 30' deep pool of water the area of a single football field. The actual AMOUNT of this high-grade waste is not by any means a problem. The problem is that we're stuck with looking after it for the next million years...also, we can usefully reprocess this stuff at any time in the future...like when the uranium runs out. The problem for storage is not that high-grade waste - but the medium and low-grade waste. Stupid things like used tools, gloves and coveralls from nuclear workers that are sufficiently radioactive that the law demand that they can't just be buried - but large in volume. The medium-grade radioactive waste is made up of things like the casings of the spent fuel rods could be recycled to make new fuel rod casings - but again, it's cheaper to store the old ones and make new ones.

The other interesting fact is that the oldest nuclear submarine in the US fleet has been more or less continuously sailing around the worlds' oceans for 30 years - and is still using the original "fist-sized" chunk of plutonium to do that. This brings home how amazingly powerful nuclear power really is!

Sooner or later (hopefully sooner), the world is going to have to come to grips with recycling and storing this stuff - because for sure we can't keep burning coal, oil and gas.

SteveBaker (talk) 19:28, 10 April 2010 (UTC)

Wheat Berries

Why are the wheat berries that ground up make flour referred to as berries, are they actual berries? And what other plants berries can be ground up to make flour? —Preceding unsigned comment added by 71.147.7.50 (talk) 17:47, 10 April 2010 (UTC)

No they are not true "botanical berries". See the article titled Berry for more details. The word berry gets applied to many different kinds of fruit. But True Berries are a specific class of plants that includes cranberries, grapes, and (surprisingly) many melons. Other plants with the name "berry" in them are not botanical berries, including strawberries, blueberries, and the various brambleberries (blackberry, raspberry, etc.) Wheat berries fit into this second class of false berries. --Jayron32 18:41, 10 April 2010 (UTC)

I thought that the normal term was "grains of wheat". Who calls them berries? Dbfirs 18:44, 10 April 2010 (UTC)

Nobody I know. In English, they are definitely called "grains". They may be called something that translates to "berries" in other languages, I suppose. --Tango (talk) 19:03, 10 April 2010 (UTC)

... and the answer to the second question (using "berries" in the "sense" of "part of a plant") can be found in our article on flour. Examples are rice, beans, nuts, some roots ... (lots more). Dbfirs 19:29, 10 April 2010 (UTC)

cf. Sugawara v. Pepsico, wherein Sugawara sued the makers of Captain Crunch cereal with "Crunch Berries", alleging that a "reasonable consumer" such as herself would be "deceived" by the description of the product's "berries" leading her to believe they're actual fruit, rather than clusters made chiefly of corn flour, sugar, oat flour, and more sugar. Sugawara lost, but someone else has filed a similar suit, this time about the fruitiness or otherwise of Fruit Loops. -- Finlay McWalter • Talk 19:30, 10 April 2010 (UTC)

That's Froot Loops. The spelling is no doubt to protect them from such lawsuits. Still, it's pretty clear there's an attempt at deception, at some level, as calling them "Froot", making them bright, fruity colors, and giving them a sweet, fruity taste and smell is obviously supposed to remind you of fruit. But, if it only fools you at a subliminal level, I doubt if you can sue for that. StuRat (talk) 20:45, 10 April 2010 (UTC)

I've encountered "wheat berries" only when they were soaked and included in a dish whole. --ColinFine (talk) 22:59, 10 April 2010 (UTC)

Bus brand

Bus wreck

I hope I am here at the right category. I already asked this question at the German Wikipedia, but nobody was able to help me. Last summer I took a photo of an old bus wreck at Arkhangelsk, Russia. I would like to know the automobile brand (maybe even type) of this bus. Unfortunately I can't ask this question at the Russian wikipedia, as they don't allow questions which aren't directly connected to Wikipedia. --Paramecium (talk) 19:10, 10 April 2010 (UTC)

A kinda-similar-looking LiAZ bus

It looks a bit like these LiAZ busses - but differs in details. We have an article about LiAZ (Russia). SteveBaker (talk) 19:32, 10 April 2010 (UTC)

Yes, I already browsed the articles about the LiAZ models. Especially the headlamps of this bus are very distinctive, but until now I didn't find a LiAZ model which looks similar. --Paramecium (talk) 20:04, 10 April 2010 (UTC)

I agree, the headlamps don't match, the window patterns are different, the engine compartment has a bigger cover and the wrecked bus doesn't have a "destination" sign on the front. However, I found a lot of pictures on Google Images of LiAZ busses - there are dozens of slightly different designs and they all have that overhanging roof and the same general 'look'. None of them match your photo exactly - but lots of them have the same design cues. It's perfectly possibly that it's not a LiAZ - but I don't see other kinds of russian bus that look anything like that - so I'd put the odds at better than 50/50. Sorry I don't have a more definite answer. SteveBaker (talk) 01:17, 11 April 2010 (UTC)

I have to ask, did they just pull that bus off the road and leave it there ? That pic doesn't appear to be a junkyard, although I do see a car behind the bus, too. StuRat (talk) 20:38, 10 April 2010 (UTC)

No, it's no junkyard. It's a small street in a quarter in the north of Arkhangelsk with many wooden houses and quite poor people. Actually it's not seldom that you can encounter such car wrecks in russian towns. --Paramecium (talk) 21:25, 10 April 2010 (UTC)

In the United States, we usually put such vehicles on cinder blocks. Nimur (talk) 22:18, 10 April 2010 (UTC)

Question about Autism

السلام عليكم لديا بعض الاستفسارات هل يحدث مرض التوحد بسبب التسمم بالمعادن الثقيلة هل لدى كثير من المصابين بمرض التوحد موهبة في الرسم والفن والكمبيوتر؟ هل يفضل دمج الأطفال المصابين بمرض التوحد مع الأطفال الطبيعين في المدارس؟ هل يوجد علاج ولو مؤقت لمرض التوحد بغض النضر علي العلاج النفسي؟ هل مريض التوحد يشعر بالنجومية في الفضاء المفتوح مع عدم التركيز علي أي شيء محدد؟ —Preceding unsigned comment added by 41.252.190.63 (talk) 22:44, 10 April 2010 (UTC)

I gave the above text to Google-translate and added a section heading:

"Peace be upon you for some friendly inquiries you happen autism because of poisoning by heavy metals is among many people with autism talent in drawing and art and computer? Is it better to integrate children with autism for natural with children in schools? Is there even a temporary cure for autism, regardless Nadar Ali psychotherapy? Do you feel sick Autism stardom in the open space with no focus on anything specific?"

To our questioner: This is the English-languge Wikipedia help desk - we expect questions in English and we can generally only reply in English. SteveBaker (talk) 01:07, 11 April 2010 (UTC)

There idea that autism is caused by heavy-metal poisoning in the womb is highly controversial - as is the idea that heavy-metals in preservatives used in vaccines are the cause. Autism is a "spectrum" condition...not all autistic people have special talents - those at the most extreme end of the range are completely cut-off from the normal world and certainly could not function in a normal school. Those at the other end may appear more or less normal and certainly should be integrated into schooling (although they might benefit from a few special classes). There isn't a cure for autism - but some of the worst symptoms (things like depression) can be treated with drugs. SteveBaker (talk) 01:34, 11 April 2010 (UTC)

The idea that autism is caused by heavy-metal poisoning in the womb is not "highly controversial"-- it is simply false. There has never been any evidence of such a relationship and the evidence against it is as strong as the evidence that evil spirits don't cause cause tuberculosis. You usually provide better answers than this, Steve. alteripse (talk) 15:01, 11 April 2010 (UTC)

Time to nitpick:

You said "the evidence against it is as strong as the evidence that evil spirits don't cause cause tuberculosis". There hasn't been any such proof on TB, has there ? Even though the cause of TB may be absolutely established, there's no way to prove that that cause, in turn, isn't caused by "evil spirits". So, that argument is rather silly.

You also said there "has never been any evidence of such a relationship". If true, that still doesn't constitute proof that the relationship doesn't exist, especially if the lack of evidence is due to a lack of studies. Also, since autism actually may be a range of disorders with similar symptoms, it's possible a small portion of them may be "heavy-metal allergies", while the majority are not. This would make any study problematic, if the percent with this sensitivity are low enough to get lost in the margin of error for the study as a whole.

I'm not saying I support the relationship, just that it's a bit early to conclude that "it is simply false". StuRat (talk) 15:53, 11 April 2010 (UTC)

Uncertainty principle

In "a brief history of time", stephen hawking emphasises that the reason we cannot precisely know both a particle's position and its momentum is not simply because we disturb the particle when we try to measure one or the other but that they actually do not have a definite position and momentum at the same time. I believed this to be the correct interpretation because, well, stephen hawking said it.

However, Ive recently been looking into the subject more and even the uncertainty principle seems to suggest that, at least, it is not fully agreed upon which interpretation is correct. In the first paragraph in particular I believe is where this ambiguity lies. From then on it seems to agree with the interpretation explained by hawking. Can someone confirm that this is the "correct interpretion" (i.e. the view held by most scientists)? --212.120.246.119 (talk) 23:40, 10 April 2010 (UTC)

I can only tell you my own interpretation, which is that the uncertainty principle causes the manifestation of an observation disturbing that which is observed. StuRat (talk) 03:36, 11 April 2010 (UTC)

It's not just observation. Mathematically, once you know the exact position, you know nothing about the momentum; once you know the exact momentum, you know nothing about the position. The key words are "exact" and "nothing." You can know a little about one and a lot about the other, but once you know one exactly, you know absolutely nothing (not exactly, not approximately, not at all) about the other. 63.17.91.51 (talk) 03:58, 11 April 2010 (UTC)

There's not really an agreed upon "correct interpretation" of quantum mechanics. See Interpretation of quantum mechanics. We can agree about the physical implications of the theory since they can be tested, but how we should understand these results is more of a philosophical question and there is no shortage of theories that have been proposed. One thing to note about hidden variable theories (where particles have an actual position and momentum even though we can't ever know them both at once with certainty) is that they have to sacrifice the principle of locality. Some people don't like that, so in that sense you could say that hidden variable theories are unsatisfying. Rckrone (talk) 04:49, 11 April 2010 (UTC)

Ignore the above answer, your question has nothing to do with interpretations of quantum mechanics (though you may find them interesting one you understand the uncertainty principle). The position of a particle is described by a probability distribution (the wavefunction) and the momentum (or possible momenta) is not an independent property but can actually be calculated from the way the wavefunction changes from place to place. A particle with a definite position has a different position probability distribution than a particle with an uncertain position, so it therefore also has a different momentum distribution. The uncertainty principle puts limits on how definite either probability distribution can be, for example, a particle with a definite position will have a momentum distribution of every possible momentum, with equal probability. 74.14.111.110 (talk) 06:22, 11 April 2010 (UTC)

OP: If for some reason you're looking at these posts in reverse order, please don't ignore my response. :(

You might find it useful (although there is always the possibly that you won't). Instead, ignore 74...'s advice to ignore my response. Rckrone (talk) 06:51, 11 April 2010 (UTC)

You may also wish to consider that, in the 22 years since the book was published, the science has moved on apace and ABHOT may be out of date. --TammyMoet (talk) 10:39, 11 April 2010 (UTC)

April 11

Torque due to gravity

http://web.mit.edu/juang/OldFiles/Public/Classes/8.012/exams/final-F02sol.pdf. For question six, the solution uses the conservation of angular momentum. But doesn't gravity exert a torque on the block? If we define our origin as the top of the cone, then r x mg isn't zero because the two aren't parallel. Thanks. 173.179.59.66 (talk) 01:33, 11 April 2010 (UTC)

The generated torque is perpendicular to the axis of rotation. Since the axis of rotation is fixed by assumption, such a torque can not change the angular momentum about that axis. Dragons flight (talk) 02:44, 11 April 2010 (UTC)

Thanks. 173.179.59.66 (talk) 05:09, 11 April 2010 (UTC)

Quantum Entanglement

Quantum entanglement can't be used to transfer information because this would violate relatvity (the data travel, if possible, would be instantanious, which would be faster than the speed of light), that part I understand. Now consider this, imagine two friends, Alice and Bob, each have a box with a particle in it. Those two particles are entangled to one amother and are in a superpositon of being the color red or blue. As soon as one of the two of them looks at their particle, decoherence will occur and the particle will be either red or blue, not both. Not only that but because the two particles are entangled, the other friends particle will become the opposite color. If Alice looks and finds hers to be red, Bobs, even though he hasn't looked yet will be blue. A soon as Bob looks he will find his to be blue and he will know that Alices must have been red. Isn't this a transfer of information? I know that Alice or Bob can't use this to transfer their own information, like one telling the other their favorite kind of pie, because the color that the particles ultimatly become when viewed is random and unpredictable. But still, isn't information still being transfer, when one looks at the color of their particle they immediatly know the color of their partners too. Wouldn't this violate relativity? Could some one please explain to me how that would be possible, am I mssing something?

The way I'd look at it is that they each already had the info on the other, they just hadn't looked at it yet. So, the info didn't travel between the two remote people at all, it was already right there in the box. StuRat (talk) 03:32, 11 April 2010 (UTC)

I agree...who needs all that funky quantum stuff? Take a matchstick, break it in half and toss each half into a box...give one box to Bob and the other to Alice (at random). Whoever opens their box and sees that they have the head of the match knows that the other person has no head on their half of the matchstick - and vice-versa. That isn't what's happening with the quantum entanglement thing (well, depending on your interpretation of quantum theory) - but the information/communication situation is indistinguishable and no laws are broken in the process. SteveBaker (talk) 03:49, 11 April 2010 (UTC)

Yeah, in this particular experiment there's nothing going on that's very interesting or problematic. Bell's theorem is that there are ways to measure the entangled particles that can't be reproduced with match sticks, but even then there's no information communicated. The test for that is, can Alice make an arbitrary yes/no decision after she and Bob part company, and then somehow let Bob figure out what her decision is faster than light. It's still impossible. Rckrone (talk) 05:25, 11 April 2010 (UTC)

What do these formulae mean?

$W={\frac {\lambda x}{d}}\,$

$v={\sqrt {\frac {T}{\mu }}}$

$\theta _{I}=\theta _{R}$

${\frac {\sin {\theta _{i}}}{\sin {\theta _{r}}}}={\frac {v_{1}}{v_{2}}}=n$

$n_{1}\sin {\theta _{1}}=n_{2}\sin {\theta _{2}}$

What do each of these various formulae mean?--Alphador (talk) 02:14, 11 April 2010 (UTC)

Welcome to the Wikipedia Reference Desk. Your question appears to be a homework question. I apologize if this is a misevaluation, but it is our policy here to not do people's homework for them, but to merely aid them in doing it themselves. Letting someone else do your homework does not help you learn how to solve such problems. Please attempt to solve the problem yourself first. If you need help with a specific part of your homework, feel free to tell us where you are stuck and ask for help. If you need help grasping the concept of a problem, by all means let us know.

MISEVALUATION--Alphador (talk) 02:56, 11 April 2010 (UTC)

You might find Snell's law a helpful article to start at. Your first equation looks like a common representation for the result of a double-slit experiment. Technically, any of these equations can mean anything, because you have not defined what the variables represent - but most of them are standard-form, standard-notation equations for some elementary optical physics. Nimur (talk) 02:44, 11 April 2010 (UTC)

And your second equation looks like uncommon notation for the frequency of a pendulum. Again, it can mean anything if you don't define v, T, and μ. Nimur (talk) 02:50, 11 April 2010 (UTC)

Thank's for the article on Snell's law, it is very helpful. I don't know what the variables stand for, that's primarily what I want to find out.--Alphador (talk) 03:04, 11 April 2010 (UTC)

You might be better off looking for more information at wherever you got those equations from. They all look like items from the waves and optics chapter of an introductory physics text. However, the symbols used in equations often vary from text to text and course to course. We could make educated guesses about what they each mean, but to be certain you'd need to know where they came from. Dragons flight (talk) 03:36, 11 April 2010 (UTC)

I do not recognize the first equation, the second equations is the speed of propagation of a wave in a vibrating string, the third one is the law of reflection, and the last two are two different ways to express Snell's law. Dauto (talk) 04:02, 11 April 2010 (UTC)

First equation could be to do with diffraction, although I would expect to see an expression involving sin(θ) on the left hand side. Gandalf61 (talk) 08:55, 11 April 2010 (UTC)

Owl species

What is the species of these owls? --Tyw7  (Talk • Contributions)   Changing the world one edit at a time! 03:02, 11 April 2010 (UTC)

• 
  Unknown owl #1
• 
  Unknown owl #2
• 
  Unknown owl#3

#2 looks like a variety of Barn Owl. --Jayron32 03:14, 11 April 2010 (UTC)

The second one is without a doubt a Barn owl (Tyto alba). The second one is maybe a Northern Saw-whet Owl (Aegolius acadicus) or a Screech-owl (Megascops)? --The High Fin Sperm Whale 03:17, 11 April 2010 (UTC)

Whale, I take it the 2nd second is really the 1st ? StuRat (talk) 03:21, 11 April 2010 (UTC)

I think the one on the left is a Little Owl -- Athene noctua, the white 'eyebrows' are the clincher. I agree that the one on the right is a Barn owl -- Tyto alba. SteveBaker (talk) 03:23, 11 April 2010 (UTC)

How about the 3rd owl? --Tyw7  (Talk • Contributions)   Changing the world one edit at a time! 04:20, 11 April 2010 (UTC)

My guess is the Great Grey Owl (Strix nebulosa). --The High Fin Sperm Whale 04:50, 11 April 2010 (UTC)

I was going with Barred Owl - but now that I look, I think I agree that it's a Great Grey Owl. SteveBaker (talk) 04:52, 11 April 2010 (UTC)

Is there a way to create a barrier to light rays that LOWERS THEIR FREQUENCY using light or energy?

I have a question.

Is there a way to create a temporary "barrier" (that does not use matter, but energy or light) that would cause all light particles that contact it to reduce in frequency —for instance, turn visible light into infrared rays, or infrared into microwaves.

And could such a "barrier" be created with energy or light waves, and not any actual physical matter? Pine (talk) 03:03, 11 April 2010 (UTC)

No - there is no such thing. SteveBaker (talk) 03:17, 11 April 2010 (UTC)

You could use gravitational redshifting. Gravitational fields contain energy, though it's not like you can just make it like you can light. Also, any form of energy will have a gravitational field, so technically that works. This only will reduce the frequency going in one direction, and will increase it if it goes the other way. — DanielLC 06:06, 11 April 2010 (UTC)

Also, there is no such thing as energy that exists by itself without associated matter or light. So by asking for a barrier made of energy but not matter you already reached the impossible, even without trying to reduce the frequency. Ariel. (talk) 07:26, 11 April 2010 (UTC)

Well, you can have energy without matter - a photon has energy, but it is a boson, whereas all matter consists of fermions. What you can't have is energy without mass (or vice versa) because of mass-energy equivalence. Gandalf61 (talk) 08:49, 11 April 2010 (UTC)

In a certain sense, you can do it with matter. Just let the light heat up an object; it will then re-radiate light at a frequency, or rather a spectrum of frequencies, determined by its temperature. If you don't let it get too hot, the bulk of that radiation will be at a lower frequency than the incoming light.

Of course this is rather indirect — it's quite unlike a frequency doubling crystal, which can be thought of much more directly as shining infrared light in and getting green light out. --Trovatore (talk) 09:30, 11 April 2010 (UTC)

Filling a volcano with water

This might sound like a strange idea but I thought I'd ask about it anyway... If you were to fill the craters of the world's volcanoes with water, what would happen? Would the cap of the volcano be kept cooler and therefore possibly stave off an eruption? And if there was a violent eruption, would the water either A) decrease the amount of ash that was ejected into the atmosphere or B) be vaporized and therefore provide the moisture necessary for that ash to rain back down sooner? Dismas|^(talk) 03:32, 11 April 2010 (UTC)

Well, if it's an active volcano, the water will likely boil away faster than you can pump it in...but eventually, I suppose, you'd make a thin insulating crust over the lava pool that might allow you to fill things up a bit. But the power of a typical volcano isn't going to be suppressed that way - either you'd end up with an explosion instead of a slow oozing of lava - or you'd maybe cause the lava to force it's way to the surface via some other route. I don't think you have a hope in hell of shutting the thing down. SteveBaker (talk) 03:40, 11 April 2010 (UTC)

Agreed. Note that many calderas already contain a crater lake. StuRat (talk) 03:43, 11 April 2010 (UTC)

Explosive volcanic eruptions (as opposed to comparatively gentle flow of lava) are directly correlated with the amount of water in the magma: more water, more explosion, since the water flashes to steam when pressure is released. Water on top of the magmatic mass would exert little cooling effect (there are submarine eruptions all the time, although explosive eruptions are suppressed in deep water by pressure). See Phreatic eruption for a discussion of the role of water in volcanism. On land, water + magma = boom. Acroterion _(talk) 03:48, 11 April 2010 (UTC)

The OP should keep in mind that the part of a volcano you can see (the mountain bit) is actually only a small part of the actual volcano. Think "iceberg". The actual structure is many orders of magnitude larger than the mountain you see at the surface; and the processes that cause an eruption occur many miles underground, and nothing you can do at the surface is going to affect it. It would be like trying to stop a bullet by placing a thimbleful of water into the barrel. --Jayron32 03:51, 11 April 2010 (UTC)

There have been some very active submarine volcanoes. Surtsey started out as a volcano 130m underwater. Kolumbo in the Aegean Sea is another example. Gandalf61 (talk) 08:42, 11 April 2010 (UTC)

Okay, so it wouldn't stave off the eruption. What about the plume of ash in the second half of my query? Dismas|^(talk) 03:53, 11 April 2010 (UTC)

No, it would just add steam and water vapor to the ash cloud. --The High Fin Sperm Whale 04:48, 11 April 2010 (UTC)

Wet ash probably will not travel as far as dry ash. The amount of ash will be the same, but it will fall down faster. Ariel. (talk) 06:51, 11 April 2010 (UTC)

I doubt even that. Any water in the caldera will be vaporized in seconds, and the mass of water that any such caldera would contain would be insignificant compared with the mass of ash. Perhaps for the first few seconds of an eruption, one might see such a wet-ash effect (and that's a very small maybe, I still doubt it will have any effect), but for the bulk of the eruption, there will be zero effect. --Jayron32 12:06, 11 April 2010 (UTC)

Destroying the Earth

Is there any weapon by which the entire planet Earth can be destroyed into pieces? --Galactic Destroyer (talk) 07:12, 11 April 2010 (UTC)

You probably want this website for complete and detailed instructions. Ariel. (talk) 07:20, 11 April 2010 (UTC)

No. (At least not one known to humans.) Axl ¤ [Talk] 08:07, 11 April 2010 (UTC)

I agree - the answer is "No". If you absolutely, utterly have to find a way to do it (eg, for quasi-believable fictional purposes) then I recommend the idea of using the Large Hadron Collider to make a particle called a strangelet - which has the peculiar property of changing anything it touches into another strangelet. This would result in a chain reaction that would result in the entire planet turning into a blob of strangelets about the size of a golf ball over the course of just a few minutes. However, the idea that strangelets actually exist is highly speculative and controversial - the idea that you could create one using the LHC is even more speculative and even less likely - and the idea that they would be stable enough (when not at the core of a large neutron star) to remain stable for long enough to achieve the destruction of the earth is yet more speculative than that. But, it's not currently known to be definitely impossible - and for the purposes of sci-fi, that's usually good enough! SteveBaker (talk) 14:03, 11 April 2010 (UTC)

Is it possible to change the orbit of a large comet using a space probe so that it can collide with earth? --Galactic Destroyer (talk) 16:04, 11 April 2010 (UTC)

Changing the trajectory of asteroids has been suggested before, usually to avoid an impact event but I don't see why it couldn't be used to create one as well. But even if you were to turn a near miss into an impact using a method like this, it wouldn't blow the world into little pieces. You'd need a huge body to do something like that, something closer to the size of the moon than the size of a comet, and I don't think it's feasible to make the moon smash into the earth with current technology. TastyCakes (talk) 16:26, 11 April 2010 (UTC)

Even the moon would not be enough. It might hurt people, the the earth itself will still be there in one piece. You would need something much larger, like venus. Ariel. (talk) 18:11, 11 April 2010 (UTC)

"Hurt people"? I'm pretty sure if you drop the moon on the Earth, you'd boil most of the seas and atmosphere and kill all macroscopic life. But you're right, the chunk of rock would mostly remain in one piece unless you somehow gave the moon far greater velocity than it has now. Dragons flight (talk) 18:20, 11 April 2010 (UTC)

Nitrogen/neon atmosphere

According to our article on the gas neon, it is a common element in the universe. So, here's a question. Let's assume you have a planet that has an atmospheric mixture of 60% nitrogen, 20% neon and 20% oxygen at say, about 0.95 atmospheres at datum level. Would there be any impediment to human life in such an atmosphere? We're assuming "liveable" temperatures here. Googling suggests that neon poses no problems re: toxicity at Earth-like conditions, but I thought I'd ask. Thanks in advance. Peter Greenwell (talk) 09:07, 11 April 2010 (UTC)

Neon is entirely inert; even moreso than nitrogen. I suspect there would be little differnce, vis-a-vis breathability with any atmosphere that was about 20% oxygen and 80% inert gases, regardless of the identity of the inert gases, be they argon, neon, or nitrogen. --Jayron32 12:03, 11 April 2010 (UTC)

Deep ocean divers sometimes use a mixture of neon and oxygen as a Breathing gas - so we have definite knowledge that it's harmless as a replacement for Nitrogen. Since it is a 'noble gas' it won't react with anything, so that's no surprise. SteveBaker (talk) 13:48, 11 April 2010 (UTC)

However, some articles related to trimix find the presence of various amounts of nitrogen (and alternative non-oxygen gases) has some effects on, for example, High pressure nervous syndrome. Those all seem to be about reducing negative effects seen at high pressure, so it's not clear if the studies are relevant to nitrogen-content at normal atmospheric pressure (i.e., where we have evolved to live, and where our "normal" for health baselines is). DMacks (talk) 17:42, 11 April 2010 (UTC)

Plants

Hi. Are there any plants that benefit from the use of a slice of lemon placed on top of the soil in a pot? Thanks. ~AH1^(TCU) 16:06, 11 April 2010 (UTC)

Not sure about lemon particularly but there are plants that like acidic soil (http://www.winsfordwalledgarden.com/development.aspx?Page=Acid_lovers). ny156uk (talk) 16:16, 11 April 2010 (UTC)

(edit conflict)I would think lemon juice (namely the citric acid) would make the soil somewhat more acidic, which would benefit any plant that likes acidic soil. But that would depend on the soil pH before you add the lemon, the amount of lemon you had and so on. I would suspect one slice wouldn't have much effect since they're not that acidic, but that's just a guess. TastyCakes (talk) 16:20, 11 April 2010 (UTC)

Note that the lemon slice will soon rot, and may give off a strong smell once it gets fuzzy. For this reason, you may do better to squeeze out some juice and discard the slice, at least for indoor plants. StuRat (talk) 16:25, 11 April 2010 (UTC)

Stains

Why are stains, especially water-based ones (even for water alone), invariably darker at their perimeter, yet frequently invisible at the center?--Shantavira|^{feed me} 17:12, 11 April 2010 (UTC)

"Invariably"^{[citation needed]}--can you be more specific about what sorts of stains you are talking about--the effect of a water-based material spreading out on the surface and/or the water (and possibly stuff it in) altering the surface itself could be two different effects. For example, if I spill water on a not-water-proof painted surface, the water can dissolve the paint at the point of the drip and carry it outward as the drop expands until the water evaporates. Repeat, repeat, repeat, and now the wood winds up bare in the middle and the extra paint spread out from it. DMacks (talk) 17:26, 11 April 2010 (UTC)

I can think of several possible reasons:

1) Miniscus. Since water droplets on non-absorbent materials are curved, there's more surface area near the edges, so, when they dry, those items carried on the surface of a drop (like dust and pollen) accumulate more on the edge than in the middle.

2) Diffusion. Since the water is pulled by capillary action along an absorbent material, and pulls the contaminants along with it, they tend to continue to be carried along until the water dries, and the stain thus forms at the boundary where the drying occurs.

3) Perception. In the middle you are comparing it with areas stained nearly the same amount, while, at the edge, you're comparing it with unstained areas. Thus, the edge appears to be stained more, by comparison. StuRat (talk) 17:36, 11 April 2010 (UTC)

The stain dries from the edges first. As it does, water plus dirt is pulled toward the edge to equalize the wetness. This causes more dirt to be at the edge vs. the middle. Ariel. (talk) 18:07, 11 April 2010 (UTC)

Systolic and diastolic blood pressure

Hi everyone, I know what systolic and diastolic blood pressures are but I'm not really sure what are the different factors that increase/decrease systolic and/or diastolic blood pressure. Can anyone explain to me what the factors are and a little about the mechanism behind it?

Thanks a million! :) —Preceding unsigned comment added by 116.15.143.83 (talk) 17:23, 11 April 2010 (UTC)

Our blood pressure article would be a good place to find this information, as well as specific articles related to Systolic and Diastolic parts. DMacks (talk) 17:30, 11 April 2010 (UTC)