i got this question in my exams . may you answer and explain

Four students set up the experiment on plotting the temperature time graph of hot body as it cools to room temperature. They all perform the experiment using identical apparatus, under identical conditions and plot their graphs on similar graph papers using similar scales. The teacher asks them to observe their graphs carefully and list down the(approximate) values of the angles, made with time axis, by the tangents to their graphs, at the beginning and towards the end of their observations. The values, noted by them, were as follows:

i dont know how to put the image.Well TEMP is on y axis and TIME is on x axis

Student A : 60^o; 30^o Student B : 65^o; 22^o Student C : 75^o; 14^o Student D : 85^o; 5^o

The best noting is likely to be that of student:

(1) A

(2) B

(3) C

(4) D

..........THANX--Myownid420 (talk) 03:51, 1 April 2010 (UTC)[reply]

Please do your own homework.

Welcome to the Wikipedia Reference Desk. Your question appears to be a homework question. I apologize if this is a misinterpretation, but it is our aim here not to do people's homework for them, but to merely aid them in doing it themselves. Letting someone else do your homework does not help you learn nearly as much as doing it yourself. Please attempt to solve the problem or answer the question yourself first. If you need help with a specific part of your homework, feel free to tell us where you are stuck and ask for help. If you need help grasping the concept of a problem, by all means let us know. ~ Amory (u • t • c) 06:26, 1 April 2010 (UTC)[reply]

Let me answer your question with another question. What temperature is room temperature? Googlemeister (talk) 13:08, 1 April 2010 (UTC)[reply]

Another relevant article is Newton's law of cooling. Heat transfer in these sorts of problems describes an exponential decay of the temperature. I'm not sure what to make of the measurement of the angles, because it depends on the temperatures, time scales, and the amount to which steady-state has been achieved. All we can say is that the measurements are all plausible. It's possible that you have graphs as well as angle measurements; if so, try to see which graphs look like an exponential temperature decay toward room temperature. For comparison, here's the omnipresent Science Reference Desk Reference Coffee/Milk Cooling Curve Simulator - the red curve shows a standard cooling curve, which should look like your hypothetical measurements. I'm going to go out on a limb and say that every one of those angle-measurements could be valid, given a particular decay time-constant. If we had enough information to calculate the decay constant, we could narrow down some more. As an engineer, I'm going out on a limb to say "steady state for decay is approximately 5 time constants"; and then, "14° is approximately 1/5 of 75°", and then, "x ≈ tan x", so let's go with C; but to be honest, unless you can personally justify any of those approximations in your specific case, I'd recommend asking your teacher for clarification. Nimur (talk) 14:03, 1 April 2010 (UTC)[reply]

Myownid420 says that he has images, but doesn't know how to put it up here. If that's the case, then the question is to basically estimate a couple of angles on a picture. We don't have the picture, so we can't possibly estimate the angles. Buddy431 (talk) 14:53, 1 April 2010 (UTC)[reply]

Nimur, all those are not plausible temperatures. If you warm up some water on your kitchen stove to 85C and then set it on the counter, it will never cool to 5C unless you keep your kitchen inside a refrigerator. Googlemeister (talk) 15:31, 1 April 2010 (UTC)[reply]

Those are not temperatures, they are angles of the tangent line of the temperature-vs.-time curve. It's slightly confusing because both angle and temperature are measured in degrees ° - but they are different things entirely. I suspect this might have been an intentional trick question. Nimur (talk) 15:45, 1 April 2010 (UTC)[reply]

Note that you can't calculate this angle, not even in principle, unless you have the graph paper. Temperature and time have different units, and only if you kow the scale from the graph paper can you convert both time and temperature into distance, after which you can calculate the angle. Might the questioner want you to use a heuristic such as "the value closest to the average of all values is most likely to be correct"? 83.134.157.144 (talk) 16:43, 1 April 2010 (UTC)[reply]

Right, but we can calculate the ratio between initial- and final- values, if we make suitable assumptions as I outlined above. We can do this because exponential functions have special properties - the tangent line is defined by the derivative, which is linearly proportional to the function value. Nimur (talk) 19:49, 1 April 2010 (UTC)[reply]

On the basis of his second reading, you'd suppose that 'D' was most likely to be correct. The temperature should be asymptoting down to room temperature - and therefore the shallower the angle for that second number, the better. But that's guessing - we know that they all stopped the experiment before the liquid reached room temperature because (strictly) it takes an infinite amount of time to do that. If they stopped it sooner then maybe 'C' got the measurements most accurately. But if some of them are sloppy experimenters (which they evidently are) then maybe the most average value is the best to take - but that's 'C' if you take the best average of the first number and 'B' if you take the best for the second. If they used 'log' graph paper then you'd expect the two angles to be the same - so now 'A' got it closest to being right. So I can make the case for any of the four experimenters to have been "the best". This is a REALLY bogus question. SteveBaker (talk) 20:01, 1 April 2010 (UTC)[reply]

Not bogus, just missing the accompagning graph I think. Without which it is a waste of time. --BozMo talk 20:10, 1 April 2010 (UTC)[reply]

I suppose so. If we could see that the graph was plotted on log graphpaper - then the answer is very different than if it's on linear graphpaper. Perhaps that's what the original questioner was trying to suggest. If it's log graph paper then I think we know that 'A' is the best answer because the slope of the graph is predicted by Newton's law of cooling and it's the same at the start and end of the experiment. Hence whichever person had first and last numbers sufficiently close together has the most accurate data. SteveBaker (talk) 20:34, 1 April 2010 (UTC)[reply]

well my question is not home work. i am a tenth standard student and my exams are over this question was in my last exam ie of practical science skills, sorry i still cant upload the photo.

let me tell you how to make it

1. make x axis and y axis of definite length
2. mar a point O(x,y) such that x=y
3. from point O draw an arc of radius less than x (slightly)
4. let this arc touch the line (0,y) and (x,o)

this was the graph that was given. i think the correct answer is D 5^o is near to 0 and 85^o is near to 90 —Preceding unsigned comment added by Myownid420 (talk • contribs) 05:01, 2 April 2010 (UTC)[reply]

Is your diagram like this sketch?

 y
  8
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  8
  8
  8
  8
  88                                   ¤
  88
  88
  8 8
  8 8
  8 ¤o
  8  8
  8   8
  8    8
  8     8
  8      ¤o
  8        8
  8         ¤o
  8           ¤o
  8             ¤¤o
  8                ¤oo
  8                   ¤¤oo
  8                       ¤¤¤ooooo
  8ooooooooooooooooooooooooooooooo888888oooooooooooo
0                                                   x

 ::Cuddlyable3 (talk) 01:55, 3 April 2010 (UTC)[reply]

If, in a reference frame O, two clocks seperated by a distance L are synchronized, then the two clocks may not be synchronized in another reference frame moving at a relative speed v. What, then, is the difference in timing between the two clocks as observed in the moving reference frame? Using length contraction and such (as per http://galileo.phys.virginia.edu/classes/252/synchronizing.html), I get Δt = vL/c^2. However, using Lorentz transformations gives me a different result: t' = γ(t - vx/c^2), t'₂ - t'₁ = γ(t₂ - vx₂/c^2) - γ(t₁ - vx₁/c^2) = γ(t₂ - t₁ +v/c^2(x₁ - x₂) = γvL/c^2. Why the discrepancy? 173.179.59.66 (talk) 05:49, 1 April 2010 (UTC)[reply]

Nevermind, I figured it out. 173.179.59.66 (talk) 05:55, 1 April 2010 (UTC)[reply]

Does the material the drinkware is made of (metal, glass, paper, plastic) really have any effect on the quality and taste of wine? Or is it just snobery? (im looking for science based answers) —Preceding unsigned comment added by 71.98.64.15 (talk) 06:21, 1 April 2010 (UTC)[reply]

Lots of materials can react with the wine to put off-tastes into it. Plastics, for example, can attract hydrophobic compounds (basically fats) which don't really ever wash off completely (if you have ever microwaved tomato sauce in a plastic dish, you know what I mean). This could redissolve in small amounts into the wine. Metals can be reactive to acids in the wine, while the wine could also dissolve flavors out of paper. Glass is the only truly non-reactive material out of which to drink. The shape of the glass also matters; remember that most of what you associate with taste is actually smell, and depending on the type of drink, the shape of the glass can be used to direct smells either to your nose or away from it. Different shaped glasses also allow differing surface area on the liquid, affecting how the wine will "breathe" (i.e. oxidize in air) which explains the shape of different stemware. Of course, for most people this will make little difference. For people that care about wine, these are big things. --Jayron32 06:31, 1 April 2010 (UTC)[reply]

For most people this make little difference only because they are not paying attention. The difference is noticible. Same thing applies to beer too BTW. Dauto (talk) 06:52, 1 April 2010 (UTC)[reply]

How noticeable are these differences? And how long does it take the wine to react to the materials? Is the wine even in the drink ware long enough to make any noticeable difference? —Preceding unsigned comment added by 71.98.64.15 (talk) 08:23, 1 April 2010 (UTC)[reply]

For comparison, pewter tankards are traditional drinking vessels in the UK, and some people keep their own tankard behind the bar at their local pub (another tradition, not of course restricted to pewterware) and/or take one along to beer festivals. However, although there is no problem with beer, which is not markedly acidic, it is now illegal for bar staff to serve cider, which is more acidic (and in the UK always what USAians call "hard", i.e. alcoholic) into pewter mugs made before 1974 when a new low-lead standard was set for the alloy, because the acidity of the cider can leach significant levels of lead from the vessel. Obviously one such drink will likely be harmless in itself, but with habitual use the effect will be cumulative. I'm not sure of the relative acidities of beer, wine and cider, but this demonstrates that the potential for reaction with wine is there.

Speaking as a regular beer, occasional cider and rare wine bibber, I myself notice a marked difference to tastes and other sensory perceptions (e.g. smell, lip feel, etc.) made by various vessel materials, and will by choice only drink from glass or porcelain vessels. 87.81.230.195 (talk) 11:24, 1 April 2010 (UTC)[reply]

FWIW, I avoid lead crystal glassware due to leeching. Imagine Reason (talk) 15:30, 1 April 2010 (UTC)[reply]

Thermal conductivity of the vessel will also have an effect, both on how quickly the liquid warms/cools to room temperature, and on the mouth feel (e.g. a cold glass may distract attention from the contents). --Normansmithy (talk) 15:46, 1 April 2010 (UTC)[reply]

Have there been any double blind studies on rather the taste difference exists or is even different enough for the human tongue to distinguish? I understand the some materials such as pewter can react with certain liquids but im look more for the taste factor. So far the answers (pertaining to taste) are based on anecdotal evidence. —Preceding unsigned comment added by 71.98.64.15 (talk) 17:03, 1 April 2010 (UTC)[reply]

You seem to be ignoring the smell answer. You can smell plastic, paper, and metal (but not glass) even with no wine in it. You can try that yourself, with your eyes closed. StuRat (talk) 17:13, 1 April 2010 (UTC)[reply]

The shape of the container is also very important as is the use of correct technique for pooring the liquid if you're talking about beer. Dauto (talk) 17:28, 1 April 2010 (UTC)[reply]

Some would assert that wine can be pretty good right out of the bottle, although proper glassware can allow better development of the olfactory aspects. Edison (talk) 04:21, 2 April 2010 (UTC)[reply]

Indeed, see for example [1] Nil Einne (talk) 04:29, 2 April 2010 (UTC)[reply]

A healthy diet must have at least a certain amount of protein,carbonhidrat and fat. For the concreteness let we assume 2000 kcal diet. He must have at least ?? kcal come from protein,?? kcal come from carbonhidrat,?? kcal come from fat. Is these amounts known? Murat Umut. —Preceding unsigned comment added by 85.102.198.65 (talk) 08:09, 1 April 2010 (UTC)[reply]

I am getting the sense in this question that every day one will eat the same thing. You know, one day you could eat a lot of protein, and the next hardly any, and that would be perfectly fine for your health. Vranak (talk) 14:12, 1 April 2010 (UTC)[reply]

This 1,357 page book from the United States Department of Agriculture has an entire chapter on protein intake recommendations, carbohydrates, fats. The recommendations are nuanced by details. So, there is more information in there than can be contained in any reasonable response; and of course, if you have special medical or dietary needs, you should consult a physician. You can get specific numbers for an average, healthy adult American male or female; for example, the USDA recommends 0.80 grams of protein per kilogram of body weight every day[2]. There is additional breakdown of recommendations in this book for other macronutrients. You will probably be interested in the Summary Tables, which specify recommendations for the nutrients you asked about; you can locate whichever age/demographic group is a close match to you, and see what is recommended. Keep in mind that your dietary needs may differ from these general guidelines. Nimur (talk) 14:43, 1 April 2010 (UTC)[reply]

A significantly less technical book is also available from the same source, for free: Dietary Guidelines for Americans, 2005. This has nice summary tables as well as description of nutrients in language that might be more accessible to a non-scientist. "Table 2" in this book breaks down recommended values for all the nutrients you asked about, with amounts specified for two recommended dietary plans. Nimur (talk) 14:49, 1 April 2010 (UTC)[reply]

Side question, for anybody knowledgeable: How corrupted are these USDA guidelines by the US food industry? Did the US food industry basically write them? Comet Tuttle (talk) 17:34, 1 April 2010 (UTC)[reply]

No, these recommendations were not written by the food industry, they were written by employees of the Federal Government: specifically, scientists, medical doctors, and nutritionists at the United States Department of Agriculture. There is a huge quantity of research that was conducted independently by federal agencies, including the USDA and the FDA; and there was independent review by scholars in academia and industry. The book I linked above has literally thousands of citations to internal studies, external publications, international and third-party research, including dissenting-opinions. It also has an entire chapter outlining motivations of the research. It's not productive to promote an unfounded stereotype about conflict of interest. It is probably true that the food industry applies pressure to shape public perception about nutrition; but the Federal Government is a pretty large organization, and to suggest that its research is invalid, or is easily pushed around by outside interests, without specifying a reason or citing any specific grievance, doesn't accomplish anything productive. Considering the relative scale of the involved parties, it is probably equally valid to insinuate that the American food industry gets pushed around on account of the recommendations of the Federal Government. Nimur (talk) 19:44, 1 April 2010 (UTC)[reply]

I haven't investigated the books or their references yet, so can't say anything to that; but I don't think you can just blow off the concern that the dietary guidelines were influenced by the food industries in the US; here's a NY Times story about the pyramid graphic being delayed a year because (allegedly) of pressure from the meat and dairy industries. The Center for Science in the Public Interest slammed the food pyramid back in 1999, and continued to complain in 2005 that the USDA has a mission of promoting US food industries that is incompatible with the mission of promoting healthy food consumption. Again, this may be giving undue weight to a couple of critics, but I think it's not something to summarily brush off. Comet Tuttle (talk) 21:22, 1 April 2010 (UTC)[reply]

The legal problems suffered by Creekstone Farms Premium Beef are a perfect example of the USDA being run by the food industry --Digrpat (talk) 00:55, 2 April 2010 (UTC)[reply]

While I have no idea what, if any influence the food industry has on the USA, I disagree that there's any evidence there that the USDA is 'run' or even unduly influenced by the food industry. The article states:

The USDA's stated position was that allowing any meatpacking company to test every cow would undermine the agency's official position that random testing was scientifically adequate to assure safety. The USDA also claims that testing does not ensure food safety because the disease is difficult to detect in younger animals

If a government agency (or whatever) is concerned the actions of some organisation is going to undermine their position or the consumers trust in them, cause undue worry to consumers or worse, mislead consumers it is understandable they may wish to prevent such actions. I'm not saying I agree with the USDA position (I'm unconvinced, but it's irrelevant anyway since this is the RD) or that their stated position is definitely the reason why they are doing what they are doing, but simply that it's entirely plausible it is their reason therefore that case doesn't in itself show that the USDA is unduly influenced by the food industry.

Nil Einne (talk) 11:57, 2 April 2010 (UTC)[reply]

I find that case troubling, too. A regulatory agency trying to limit safety testing at a private company is bizarre behavior. It's difficult to see how limiting testing will improve food safety, which is supposedly the goal of the regulatory agency. On the other hand, limiting testing can lower prices, but that's not supposed to be the goal of regulatory agencies. Note that there are many other decisions by the FDA which also imply a tilt towards industry and against consumers. Just in the food area, we also have the decision not to require labels on genetically modified foods, the ban (until recently) on selling natural stevia as a sweetener while simultaneously allowing the sale of much more dodgy artificial sweeteners pushed by chemical companies, failure to require nutrition labels on fast food items, failure to ban added trans-fats, and having their inspectors only perform visual checks on meat. There are too many instances to list in the drugs area. While any individual instance could be debated, the total makes a strong case for a regulatory agency that was, indeed, controlled by the industry they were supposed to regulate. StuRat (talk) 13:36, 2 April 2010 (UTC)[reply]

Thank you Nimur, this is what I was looking to find. I hope that it will help me convincing my friend that his diet is unhealthy. Murat Umut.85.102.198.65 (talk) 15:29, 2 April 2010 (UTC)[reply]

Unlike other polyatomic ions, such as carbonate and sulfate, the phosphate ion can form two partial ions, H₂PO₄^- and HPO₄^2-. What are their names? Are they called biphosphate and triphosphate, or something else entirely? --Natrium-23 (talk) 15:37, 1 April 2010 (UTC)[reply]

HPO₄^2- could be called "biphosphate" but the "bi" there doesn't mean two, it means hydrogen. Compare with bicarbonate and bisulfate. More formally, the IUPAC recommends explicitly using "hydrogen", so HPO₄^2- would be "hydrogen phosphate", and H₂PO₄^- would be "dihydrogen phosphate". If you read the phosphate article carefully, you'll notice that these are the terms used. -- 174.31.194.126 (talk) 16:21, 1 April 2010 (UTC)[reply]

You will frequently see them called "Monobasic" and "dibasic" on the label of the dry chemical, for example, NaH₂PO₄ = "sodium phosphate, monobasic".[3] This is obviously not the IUPAC nomenclature. -- Flyguy649 ^talk 16:30, 1 April 2010 (UTC)[reply]

Actually, the "bi" in "bicarbonate" and "bisulfate" DOES mean 2, and not hydrogen. It is the monovalent form of a divalent ion, so, for example, sodium bicarbonate contains twice as many anions as does sodium carbonate. The name was devised before the structure was fully understood, so when named people noticed that it would take twice as much bicarbonate to precipitate the same amount of a cation as an equivalent amount of carbonate, hence the name "bicarbonate". As far as the phosphate series goes, generally the names are "Dihydrogen phosphate" and "hydrogen phosphate" OR "phosphate, monobasic" and "phosphate, dibasic", as already noted. --Jayron32 21:02, 1 April 2010 (UTC)[reply]

There was a guy, an American scientist, who took carbon dioxide readings starting in the 1930s or 40s and did these readings every day until his death in the 1990s, which were then taken over by his son. Ronald Reagan employed a group of scientists to dispute this scientist's findings, but the scientist group found the same thing that carbon dioxide atmospheric levels were indeed rising. The question is, who is this scientist guy and do we have an article about him? I just got told a story about this by someone.--I have winnie the poo tatoo and im 8 (talk) 19:15, 1 April 2010 (UTC)[reply]

I believe you are thinking of Charles Keeling who began his nearly daily Keeling curve in 1958. There are some direct measurements of atmospheric CO2 before that, but they are discontinuous and tend to have much greater uncertainties due to less accurate techniques. Most CO2 records of periods before 1958 are based on studying gas bubbles trapped in ice cores. Dragons flight (talk) 19:21, 1 April 2010 (UTC)[reply]

I took this photo today of a squirrel on the grounds of the American Museum of Natural History in NYC -- it's sort of reddish and the bushiness of the tail is somewhat compressed dorso-ventrally. Doesn't look like an eastern gray squirrel to me -- any ideas? DRosenbach ^{(Talk | Contribs)} 00:32, 2 April 2010 (UTC)[reply]

Columbian ground squirrel perhaps? --The High Fin Sperm Whale 01:03, 2 April 2010 (UTC)[reply]

Looks to me like a thinner version of eastern gray -- in that it would be a tree squirrel. DRosenbach ^{(Talk | Contribs)} 01:09, 2 April 2010 (UTC)[reply]

the Columbian ground squirrel occurs in the western U.S., not the East. Rmhermen (talk) 04:23, 2 April 2010 (UTC)[reply]

I want to make my own teleprompter and need to get the one way mirror glass. I live in the UK. My ebay searches aren't yielding anything except this privacy film - would that be likely to work, stretched over some clear acrylic? Proper teleprompter mirrors have an antireflective coating on the camera-side of the mirror.. not sure whether I can prepare such a surface? --78.151.30.114 (talk) 00:55, 2 April 2010 (UTC)[reply]

While I don't know whether you're right or wrong about the anti-reflective coating, I have a suspicion that you may have a misunderstanding of how a two-way mirror works (the proper name is two-way mirror, and that's also the name that correctly describes how it works). A two-way mirror reflects from both sides, and it lets light through from both sides. The reason you perceive it as a mirror from one side and a window from the other has to do with the relative intensities of the transmitted signal versus the reflected one. If you're on the bright side of the mirror, then the reflected signal is brighter (simply because there was more light to start with), and in your eye and/or your brain, it drowns out the signal from the dark side so that you are unable to perceive it.

(Sorry that I don't know where to buy it.) --Trovatore (talk) 01:03, 2 April 2010 (UTC)[reply]

• Both one-way mirror and two-way mirror are commonly used names, and they both make sense, so let's not be saying that only one of them is "proper". "One-way" makes sense because you can only see one way through it. "Two-way" makes sense because it behaves in two ways when seen from different sides. --Anonymous, 04:10 UTC, April 2, 2010.

No, one-way mirror is wrong, period. It should never be used. It encourages people to think that there is some directionality to the mirror. --Trovatore (talk) 07:46, 2 April 2010 (UTC)[reply]

There is directionality. The lighted side and the dark side. But you knew that. --Anon, 10:43 UTC, April 2, 2010.

And it does not "behave in two ways when seen from different sides". It behaves in exactly the same way. (Well, at least in principle -- in practice of course one side could be dirtier than the other or something.) This is a very key point -- if you don't understand that, then you don't understand the gadget at all. --Trovatore (talk) 07:49, 2 April 2010 (UTC)[reply]

It does. It allows you to see what is on the same side when you look into it from the lighted side, and allows you to see what is on the other side when you look into it from the dark side. The symmetry of the underlying mechanism is irrelevant to that fact. And you knew that too. Now please stop telling people what not to say. --Anon, 10:43 UTC, April 2, 2010.

I will not. People should not say one-way mirror. It makes people think that the device is directional, which it is not. On the bright side, you see a roughly equal mix of the bright image and the dark image. And on the dark side, you see a roughly equal mix of the bright image and the dark image. --Trovatore (talk) 17:35, 2 April 2010 (UTC)[reply]

It is directional, because it has a bright side and a dark side, which it relies on to work. (An ordinary window works as a one-way mirror, at night.) If it doesn't have the bright side and the dark side, it won't work, and therefore isn't a one-way mirror (or a two-way one, which is the same thing). 81.131.62.171 (talk) 02:47, 5 April 2010 (UTC)[reply]

It is not directional. On both sides, it gives you a roughly equal mix of the image from both sides. That's what it means for it to "work", and it does that even if the lighting is equal on both sides.

It is properly called a two-way mirror, because it acts as a mirror in both directions. An ordinary mirror works as a mirror in only one direction, and therefore would be the correct referent for the term one-way mirror. Of course you can't use that term that way because of the potential for confusion. --Trovatore (talk) 08:07, 5 April 2010 (UTC)[reply]

Yeah, but when you construct a box around the camera, there is little light on that side of the mirror, so it works (text is reflected from the screen while the camera receives light from the other side of the mirror). --78.151.30.114 (talk) 01:30, 2 April 2010 (UTC)[reply]

Actually from looking at the diagrams in the teleprompter article, I think the reason the audience (or camera) doesn't see the text has less to do with the relative illumination than with the angle of the mirror. A two-way mirror is essentially a beam splitter. The text is projected up at the mirror from below. Part of the image is reflected towards the speaker; the other half (or so) of it continues up to the ceiling. Essentially none of it goes to the audience, just because the audience is not in the right place to see it. --Trovatore (talk) 01:45, 2 April 2010 (UTC)[reply]

It is also called a "Half-silvered mirrot." Edmund Scientific always had them for sale. Random local glass stores also offered half silvered mirrors for sale. A simple piece of glass would also work nicely, as in the old "Pepper's Ghost" effect. Edison (talk) 04:19, 2 April 2010 (UTC)[reply]

I prefer the name "half-silvered mirror". It makes it clear that it reflects half the light and allows half of it through (roughly). Once you understand that, the behaviour of the mirror is obvious. --Tango (talk) 13:47, 2 April 2010 (UTC)[reply]

I think there is some confusion here over the type of teleprompter being used. The OP wants a teleprompter that allows someone to look into a camera while reading. I think Trovatore is thinking of the teleprompters people use when they want to read while looking at a live audience (the type Obama is (in)famous for using). I think they both use half-silvered mirrors, but in slightly different ways (although I suspect the second type may be less-than-half-silvered, since that will look better from the audience side and you can compensate by just using a brighter projector, the first type could also use a less-than-half-silvered mirror but there is less benefit since the two sides are lit different amounts). --Tango (talk) 13:47, 2 April 2010 (UTC)[reply]

What is the cause of rings around Uranus?--79.76.175.65 (talk) 01:10, 2 April 2010 (UTC)[reply]

The same as the reason for rings around Saturn, Jupiter, and Neptune. When rocks and particles are sucked into orbit, due to centrifugal force, they flatten out. Shepard moons help 'herd' the rings into specific bands. You may also want to read Rings of Uranus. --The High Fin Sperm Whale 01:13, 2 April 2010 (UTC)[reply]

Poor hygiene?. --Jayron32 04:11, 2 April 2010 (UTC)[reply]

Is there no end to these pseudo funny comments about Uranus?--79.76.239.84 (talk) 02:58, 7 April 2010 (UTC)[reply]

What does Shepard have to do with moons? Or did you mean "shepherd moons"? 24.23.197.43 (talk) 05:51, 2 April 2010 (UTC)[reply]

Or even Shepherd moon. Mitch Ames (talk) 07:55, 2 April 2010 (UTC)[reply]

Also, the large planets all have many moons, and the gravitational interaction between them and the planet seems to prevent the rings from coalescing into additional moons. There are smaller planets with multiple moons (Mars has at least 2 and Pluto has at least 3), so perhaps there could be tiny rings there, but I'm not aware of any having been found. StuRat (talk) 13:10, 2 April 2010 (UTC)[reply]

In various places it seems that it is the short duration of and accumulation or flow of enough CO₂ in low spots or ditches or even down a hillside slop and even flat ground to make impossible a breath of fresh air after 2 or 3 breaths that any air breathing life form has collapsed and within seconds to minutes succumbed and died even if air returned within 5 minutes and even if air was in reach of the life form if it stood on its toes or raised its head. This attests to the power of CO₂ to knock an animal out quickly but my question is if instead of Nuclear Winter caused by an asteroid striking Earth and killing everything an accumulation of CO₂ could be enough from burning matter and release by shock to have killed off most of the dinosaurs? 71.100.3.207 (talk) 02:30, 2 April 2010 (UTC)[reply]

Seems like it would take a lot of carbon dioxide to give enough blanket to enough area. "Everything" on the terrain can't be ditches:) More than just filling low areas and sweeping down hills, you have to get over hills to spread over a continent-sized region.. But certainly the situation has occurred on town-size areas. See for example Lake Nyos. DMacks (talk) 02:46, 2 April 2010 (UTC)[reply]

Agreed. My understanding though is that in the Permian-Triassic extinction event 251 million years ago, which was even worse than the mass extinction that killed the dinosaurs and is thought most likely to have been caused by enormous volcanic eruptions, there is evidence that high CO₂ concentrations played an important role in killing large animals. Looie496 (talk) 03:19, 2 April 2010 (UTC)[reply]

The phenomenon which raises this question is the strange accumulation of bone in some places as if they were all living int the same town and the dam broke sweeping them down river to accumulate in eddies and other spots. 71.100.3.207 (talk) 04:28, 2 April 2010 (UTC)[reply]

That's probably closer to the true explanation than carbon dioxide poisoning. After all, there are natural dams. We have beaver dams now, and, although they aren't large enough to cause that type of damage, perhaps some ancient creature did the same thing on a massive scale ? If not, there's still ice dams/glacial dams. You can also get flash floods from sudden rains, without the need for a dam to burst. Another source of floods is when a lake or sea is held back by rock, and that rock collapses. This can happen in a lake in a caldera, for example, and may also have allowed the Mediterranean Sea to catastrophically flood into what became the Black Sea. See Black Sea deluge theory. StuRat (talk) 12:53, 2 April 2010 (UTC)[reply]

This has been known in modern times; see Lake Monoun. Tonywalton ^Talk 18:28, 4 April 2010 (UTC)[reply]

For the actual condition that causes CO2-laden air to be unbreathable, see carbon dioxide poisoning and carbonic acid. Another cause of the Permian-Triassic extinction may have been hydrogen sulfide. ~AH1^(TCU) 23:42, 4 April 2010 (UTC)[reply]

Why is my dog's nose so juicy? I would like to know where all this juice comes from, because sometimes it is so wet I am tempted to get a towel and dry it off. What causes all this juice? I'm not at all concerned about my dogs health; she is completely healthy, she just has a juicy, juicy nose! It's not dripping, like with snot it's just always cold and totally wet. I am wondering *where* this juice comes from. I'm not the only person in the world that has a dog with a juicy nose. I see them all the time. Thanks.70.245.24.14 (talk) 04:51, 2 April 2010 (UTC)[reply]

If you are concerned about your dog's health, you should take them to a veterenarian. Medical advice, even regarding animals, isn't reliable when it comes from random strangers in teh interwbz. --Jayron32 04:58, 2 April 2010 (UTC)[reply]

Did you miss the words "not at all"? --Anon, 10:45 UTC, April 2, 2010.

Dogs have all this juice on their noses to help them smell. This does not mean they are unhealthy. Regards, --The High Fin Sperm Whale 05:18, 2 April 2010 (UTC)[reply]

The High Fin Sperm Whale, thank you but where does the juice originate from? That is the nature of my question. Are there some sort of nose glands that produce this juice. 70.245.24.14 (talk) 05:26, 2 April 2010 (UTC)[reply]

The article mucus explains a bit about this. See also Mucous membrane and Goblet cell. --Jayron32 05:35, 2 April 2010 (UTC)[reply]

Google-ing "dog wet nose" gets tons of hits. One that I found interesting says that the role of the moistness is to help in evaporative cooling. Following some links, the main organ involved in this process seems to be the lateral nose gland. If you want the source for this info, try this article from Science. Other links say that the wetness comes from the dog licking their nose, which I can certainly believe, having observed my own dogs, but I couldn't find any primary sources on that one (not to mention the question of whether the licking is a cause or effect of a wet nose). --- Medical geneticist (talk) 11:46, 2 April 2010 (UTC)[reply]

I've always thought of most animal noses as inside-out relative to humans. That is, the portion that's inside and always kept moist on humans is outside (and inside as well), on dogs. This is likely part of their much better senses of smell. The glands that keep it moist are similar to our sweat glands. StuRat (talk) 12:37, 2 April 2010 (UTC)[reply]

Yes - and part of the reason for that appears to be to give them a better directional sense of smell. When all of the little detectors are up inside your nose, all you can really tell is which nostril the smell came through - but dogs (in particular) have a completely directional sense. SteveBaker (talk) 14:21, 2 April 2010 (UTC)[reply]

Anecdotally, it comes from their tongue. Dogs lick their noses, for olfactory (smell) and evaporative (cooling) benefit. After sleeping a dog's nose is often dry and warm. I suspect that's because dogs don't lick their noses while asleep. Some dog-health related websites identify dry nose as a 'possible' indicator of illness, but this is apparently a poor indicator since plenty of healthy dogs can have occassional or non problematic dry noses. Lastly, for comparison, compare dog noses to human lips... Ours stay moist from us licking them as well. 206.53.153.110 (talk) 13:09, 4 April 2010 (UTC)[reply]

Ah yes, the good old juicy nose. Forgive me, but perhaps a new juice could hit the market. To go with V-8, we could call it K9! 10draftsdeep (talk) 20:24, 5 April 2010 (UTC)[reply]

For those who have a working knowledge of historic aircraft (especially those made by Lockheed): did the Electra 10-E have a hydraulic system (and I don't mean just the oleo-struts), and if so, what components did it actuate? I'm pretty sure the primary flight controls were all mechanical, as on all other aircraft at the time (AFAIK hydraulic boosters did not begin to be fitted to aircraft until after World War 2, and even then only to the highest-performance jet planes at first); my question is, was there anything else vital to the plane's safety (like flap controls, or landing gear retraction) on the Electra that was hydraulically powered? And no, in case you're suspicious, this has nothing to do with any fringe theories about Amelia Earhart's disappearance; it's for a novel that I plan to write some time in the future. Thanks in advance! 24.23.197.43 (talk) 06:31, 2 April 2010 (UTC)[reply]

Anybody? OK, I'll make it a fuel leak, then (or maybe an engine fire).  :-) 24.23.197.43 (talk) 04:48, 3 April 2010 (UTC)[reply]

Sir, please send me the drive internal connection diagrams ie, IGBT, RECTIFIER,IVERTER etc

Thanking you sir, S.G.Rabbani —Preceding unsigned comment added by Sgrn70231 (talk • contribs) 07:01, 2 April 2010 (UTC)[reply]

Our inverter (electrical), rectifier, and IGBT articles contain circuit diagrams. StuRat (talk) 12:43, 2 April 2010 (UTC)[reply]

From my office window, I look out over an apartment complex which contains dozens of large, mature, deciduous trees. These appear to be of identical species (sorry - I'm clueless as to what species they are - but I don't think that matters). They are all more or less the same size (40 feet maybe). Presumably they were all bought from the same tree supplier on the same day and planted when the apartment complex was first built. So they ought to be pretty close to identical...possibly even genetically similar or perhaps identical if they were grown from cuttings rather than seed. I'd guess that they are of some fairly fast-growing species.

But they are all slightly different shades of green - some slightly yellowish, some subtly brownish, some are a really vivid almost "lime" green. They all seem pretty healthy though - the color differences are pretty subtle - they aren't brown as in "Autumnal", it's spring here in Texas and the leaves are all pretty new.

Given that everything else is the same (species, age, etc) I presume that this must be due to differences in soil chemistry, available sunlight and amount of water available.

It's also noticable that the color of all of the leaves of a particular tree are identical in color - even though some parts of the tree are in more or less permenant shadow between these large buildings and other parts are getting plenty of light because they are ten feet above the roof-line.

But (chemically) what is changing in the leaves? Is it just a matter of whether there is more or less chlorophyll - or is it the presence of different amounts of some other colorant?

I'm curious because I do computer graphics and I'm wondering about what might constitute a realistic range of randomized colors for otherwise identical trees - I'll probably end up just having one of our artists go and make an artistic choice - but it would be nice to actually understand what's going on. For example, if the differences are only in chlorophyll levels - then it's likely that only the amount of green is changing from tree to tree...but if it were wildly varying amounts of some reddish compound then the answer is different.

SteveBaker (talk) 14:39, 2 April 2010 (UTC)[reply]

I know that in aerial overflight imagery, the most common cause of coloration difference in vegetation is amount of water. This is especially detectable in infrared channels (also picking up amount of chlorophyll). You may be seeing variations of the water table or phreatic surface on a meters-scale level. Whether the quantity of water is a biological cause for a variation in chlorophyll quantity/quality is a question for a botanist... Nimur (talk) 15:33, 2 April 2010 (UTC)[reply]

(ec) The colour of leaves is determined by a combination of various pigments (such as carotenoids), including chlorophyll (those other pigments are what give the autumnal colours). There are also different types of chlorophyll, with slightly different colours (see Chlorophyll). Since it is currently spring, the difference could be due to differing ages of the leaves (young leaves are often yellower than old ones). If the trees get different amount of sunlight, they may be a few days ahead/behind each other. If that is the case, I would expect the differences to reduce over time - I suggest you take daily photographs and compare them. I would expect the soil to be very similar over such a small area (unless different plants had been grown there previously, I suppose). There could be differences in water, though. --Tango (talk) 15:35, 2 April 2010 (UTC)[reply]

(ec) I'd go with the amount of chlorophyll. Note that new leaves are often also a very different shade of green than last year's growth, so the ratio of new leaves to old would affect the overall color. And the percentage of new leaves could depend on water, sunlight, temperature, how many old leaves are retained, and many other factors. StuRat (talk) 15:38, 2 April 2010 (UTC)[reply]

Hi. I am trying to understand what differences there are between power transmission lines that are part of the power grid and power lines that you would find above an electrified train track. I imagine that the power lines are usually almost continuously transmitting electricity, but that overhead train lines are only doing so, when trains pass, and also that far power power passes down power transmission lines than overhead train line. I would also like to understand if the electromagnetic radiation from overhead train lines is at all comparable to the radiation from power transmission lines. Any help would be appreciated. Thanks GregB1968 (talk) 15:47, 2 April 2010 (UTC)[reply]

For the train, they use two power lines, one positively charged and one negative, so that no electricity should flow until the train completes the circuit. I suppose regular power lines are similar, with the appliances at the end being what completes the circuit. However, unlike the train case, the circuit is always completed by many thousands of appliances, so electricity is always flowing. StuRat (talk) 15:57, 2 April 2010 (UTC)[reply]

Our article on overhead lines explains their use for public transport / train systems. They may use mechanical schemes to keep them from breaking under the constant attachment of the train's electrical paddle or connector. Typically, they are higher voltage than the residential circulation lines; voltages vary anywhere from ~ 1000 volts (e.g., San Francisco Muni) to much higher (~ 10 kV in Germany. Sometimes, they also operate at a different AC frequency. Consequently, they have different power distribution and substation implementations; but otherwise, they are not very different from standard transmission lines. Nimur (talk) 16:13, 2 April 2010 (UTC)[reply]

Railway electrification systems usually use the tracks as the one "line" and the overhead as the other. Therefore, only when a train makes a circuit is power transmitted. Power for trams and light rails are typically 750 V DC, while mainline trains may be either DC (typically 1500 V or 3000 V) or AC (15 kV or 25 kV are the most common). With so high voltage, it is often not necessary to have a parallel feeding system, although unless the trains use a different frequency than the power grid (50 Hz in Europe; 60 Hz in North America), they can simply feed from the local grip at regular intervals. Arsenikk ^(talk) 17:11, 2 April 2010 (UTC)[reply]

Thanks for all the input, so far. There is a rail line near to my place of work (Hertford Loop Line) which seems to be 25 kV AC line. The power transmission article seems to suggest that power lines are usually greater than 110 kV. I am wondering what impact that has on electromagnetic radiation. Does the much lower voltage mean that there is much less radiation, and does the fact that there is only intermittent power transmission on the rail line, mean that there is only intermittent electromagnetic radiation (i.e. only during actual power transmission)? Thanks again for the help so far. GregB1968 (talk) 17:38, 2 April 2010 (UTC)[reply]

Stu also even if there no appliances or anything in use, most power lines are at such high voltages that if you touch just the positively charged line, electricity will arc across from the negatively charged one and through your body.--92.251.179.38 (talk) 18:31, 2 April 2010 (UTC)[reply]

One additional question on railway power. I once slept in room in Bremen an in the dark I could see a Cold cathode flicker each time a tram was passing. Next morning I checked and I saw that a steel cable, holding the isolated power cable, was attached to the wall in the room were I was staying. How does enough energy get into my room that a cold cathode is giving light. --Stone (talk) 18:58, 2 April 2010 (UTC)[reply]

It takes very little energy to make a fluorescent light flicker. StuRat (talk) 19:05, 2 April 2010 (UTC)[reply]

If the power is DC there is almost no electromagnetic (radio wave) leak. But there is a (stationary) electric and magnetic field around it. Are you referring to electromagnetic sensitivity? If you are, since it's fictional, I can't tell you if a railway power line is better or worse. Ariel. (talk) 19:11, 2 April 2010 (UTC)[reply]

Thanks Ariel. I would just like to understand if there is an electromagnetic field, even if there is not a train passing. I really don't understand electricity at all, but I think that the voltage of the cable is just the energy potential between two point, whereas the current is actually the flow of electrical energy. With transmission cables, I am guessing there is typically a current because there is usually always something drawing current from the grid, whereas with the trains, there is only current drawn when there is a train drawing power. What I am not clear on, is whether the electromagnetic field is caused simply by having a cable which is "live", or whether it is only when there is current drawn. I did read an article elsewhere that suggests there is a large electromagnetic field near the floor of many train carriages but, of course, that doesn't clarify whether the field is always there even if there is no train. Any more help appreciated. Many Thanks GregB1968 (talk) 12:51, 3 April 2010 (UTC)[reply]

Any charged object (like live DC electrical wires, even in an open circuit) will have an electromagnetic field around it. Your exposure to that field varies with the strength of the charge and (the square of) your distance from it, of course, but also the material between you and the charged object. Insulators provide some protection, but are not perfect. A Faraday cage (a mesh of conductors designed to cancel the field) is another way to block EM radiation. StuRat (talk) 15:19, 3 April 2010 (UTC)[reply]

Thanks Stu. So presumably the cables would be considered charged, even if no current is being drawn. Is that right? If I wanted to measure the field around a power transmission line, or an overhead rail cable, which kind of monitor would I use? I Googled electromagnetic detectors, and got this page - [4]. Of the detectors listed there, would an AC gaussmeter be the most appropriate (assuming that the cable in question was AC)? Thanks again GregB1968 (talk) 17:15, 3 April 2010 (UTC)[reply]

I failed to say that only DC electrical wires would have a charge in an open circuit, so I now added that up above. (In fact, I don't think AC wires would show a charge, even when electricity is flowing.) As for the meter, it sounds to me like you are interested in all types of electrical and magnetic fields and radiation, so you should probably get a general purpose meter. StuRat (talk) 18:37, 3 April 2010 (UTC)[reply]

Thanks. I read up a bit more on this [5], and what I read seems to suggest that there is an electric field when the cable is charged, but a magnetic field only when there is a current flowing (not sure if this varies between DC and AC). I wonder if this means that there would only be a magnetic field when a train passes, but an electric field all the time. I've got to say that I am getting more confused :) When people talk about an electromagnetic field, is that actually two fields (electrical and magnetic), or is it a magnetic field generated by an electrical source (i.e. a current passing through a conductor). Thanks again. GregB1968 (talk) 19:44, 3 April 2010 (UTC)[reply]

There are three fields here, and they are related but different. Electric, Magnetic, and Electromagnetic. Electromagnetic is photons, and radiates away from the conductor. Electric exists in a charged conductor (voltage, not current), Magnetic exists with current (current, not voltage). Electromagnetic exists in a changing field (of either type). (That's simplistic, but I hope accurate.) Ariel. (talk) 01:06, 4 April 2010 (UTC)[reply]

As far as physicists are concerned, electromagnetism is one fundamental force, with different manifestations. Thus, electricity creates magnetic fields and magnetism creates electric fields. StuRat (talk) 01:11, 4 April 2010 (UTC)[reply]

So would it be correct to say that, for DC with absolutely no current flowing, there will be only an electrical field (from the charge), but that for flowing DC and from AC (where some current flows most of the time), there will always be an electromagnetic field? And in the case of the flicker on a fluorescent light, I assume it is the high inductance of the choke that picks up the E-M field (a single flash when the current changes in DC, or a continuous 50/60 Hz flicker from a strong AC field). Would an old choke connected to a "mains tester" screwdriver serve as a very cheap E-M field detector? (I'll try it!) Dbfirs 08:32, 5 April 2010 (UTC)[reply]

from where can i get 100% free scholarship for mbbs? —Preceding unsigned comment added by 117.102.16.126 (talk) 16:59, 2 April 2010 (UTC)[reply]

Are you referring to the medical degree? Your IP address says you are in Pakistan, is that where you want to study? --Tango (talk) 17:02, 2 April 2010 (UTC)[reply]

All medical schools in Pakistan use the Bachelor of Medicine, Bachelor of Surgery (MBBS) degree. Not sure how you would obtain a scholorship but usually such schemes are done directly by the medical schools (e.g. for very good grades at pre-medical level) or they are subsidised by a company in return for you working for them after the degree. Though the latter is rare for being a doctor, you may be able to find a research institution who could fund you if you find that you have exceptional ability and you sign an agreement to work for them post-qualification. Regards, --—Cyclonenim | Chat  21:43, 2 April 2010 (UTC)[reply]

I've always wondered how proton beams for colliders, like the Large Headron Collider, are created. Are the beams exclusively protons? If so, what element is used for the protons? And how are the protons "separated out"?

Thanks —Preceding unsigned comment added by Spodeworld (talk • contribs) 17:39, 2 April 2010 (UTC)[reply]

I don't know for sure, but I would assume that they just ionize hydrogen using an electric field, which also serves to separate the protons and electrons. -- Coneslayer (talk) 18:11, 2 April 2010 (UTC)[reply]

There are lots of types of ion sources for linear accelerators. Unfortunately, proton beam in particular is a redirect to proton, which talks nothing about that topic. DMacks (talk) 18:26, 2 April 2010 (UTC)[reply]

We should probably get together and try to fix that. Theresa Knott | token threats 18:34, 2 April 2010 (UTC)[reply]

It's amazing that we have a Proton pack article but not a real proton beam article! --Mr.98 (talk) 00:55, 3 April 2010 (UTC)[reply]

Coneslayer is correct. Dauto (talk) 18:39, 2 April 2010 (UTC)[reply]

[6] states that they come from a Duoplasmatron. There they are created by a electron beam kicking electrons from a gas and the created ions are extracted by a magnetic field. Cern shows a bottle of hydrogen for the Linac 2 Pre-Injector --Stone (talk) 18:49, 2 April 2010 (UTC)[reply]

What would happen if someone built an engine that propel a spacecraft at 1,079,252,851 km/h? Supposing we found some method of propulsion that could potentially provide the necessary power, and lets say it's travelling through a complete vacuum so it doesn't get blown all to hell by the friction, is there any reason why the spacecraft couldn't achieve that speed?--92.251.179.38 (talk) 18:25, 2 April 2010 (UTC)[reply]

That's a little bit faster than the speed of light so the answer is NO, it can't be done. Dauto (talk) 18:30, 2 April 2010 (UTC)[reply]

See special relativity Theresa Knott | token threats 18:31, 2 April 2010 (UTC)[reply]

You see this is what I was expecting. But obviously there's nothing stopping us from building such a propulsion system. What would happen as the craft neared the speed of light?--92.251.179.38 (talk) 18:33, 2 April 2010 (UTC)[reply]

As you accelerate the craft its energy increases which by the Einstein's formula E=mc² means its mass also increase making it harder and harder to accelerate (More inertia). To reach the speed of light you would need an infinite amount of energy which is not possible. Dauto (talk) 19:00, 2 April 2010 (UTC)[reply]

"obviously" ? Energy (speed) has mass (weight). So as you speed up the craft it gets heavier. In order to speed it up some more, not only do you have to speed up the original weight of the craft (called the rest mass), but also all the additional mass from the energy (called the relativistic mass, and don't for a second think this mass is fictional, or just a mathematical concept - it's totally real). The more you speed it up, the heavier it gets, the heavier it gets the harder you have to push to speed it up - but that very hard "push" uses a lot of energy, so it gets even MORE heavy from all that additional energy. The result is that when you hit the speed of light the mass becomes infinite, so no matter how hard to push, you just can't move it.

Well, you can't hit the speed of light, so it doesn't mean much to say the mass is infinite at the speed of light. The energy required to reach the speed of light (which you calculate as an integral) is infinite. --Tango (talk) 19:31, 2 April 2010 (UTC)[reply]

And why is it infinite?--92.251.142.219 (talk) 15:18, 3 April 2010 (UTC)[reply]

Here is the relativistic formula for the kinetic energy ${\displaystyle K\,}$ of a particle of mass ${\displaystyle m\,}$ moving at speed ${\displaystyle v\,}$.

${\displaystyle K=mc^{2}\left[{\frac {1}{\sqrt {1-{\frac {v^{2}}{c^{2}}}}}}-1\right]}$.

Where ${\displaystyle c\,}$ is the speed of light. Just plug ${\displaystyle v=c\,}$ in the formula and you will see that you get infinity. Dauto (talk) 15:37, 3 April 2010 (UTC)[reply]

Special relativity gives a good explanation of what happens—the mass of the craft increases, it starts to perceive time as being slower than other reference frames, its size gets smaller as viewed from other reference frames, and the energy needed to keep it going increases. You can't hit the speed of light this way, or go beyond it—the physics just doesn't work out. If you could get to it (which you can't), the end result would be that its size would be nothing, its mass would be infinite, and its perception of time would stop (if I understand it correctly—I am sure there is a more subtle way of saying those things). The faster-than-light article is a good discussion of why current science says it won't work, and gives some problems with making loopholes in current understandings as a way to get around this constraint. Our theories would have to be substantially wrong (or missing something huge) for this to work out. (Which is always possible, but you'd have to get your new theory to jibe with the rest of the observed data, which would be a non-trivial task! You probably aren't going to manage it!) --Mr.98 (talk) 22:05, 2 April 2010 (UTC)[reply]

What would be the average time of survival after being nailed to a cross by ancient Romans and the time of death? 71.100.3.207 (talk) 19:29, 2 April 2010 (UTC)[reply]

It depends on the details. See Crucifixion#Cause of death. --Tango (talk) 19:41, 2 April 2010 (UTC)[reply]

Assuming ideal conditions (hah!), ie no blood loss, toxic shock, torture, or extreme exposure to heat or cold, the limiting factor would probably be water, without which humans can rarely survive more than 3 or 4 days. All of the afformentioned factors would greatly increase perspiration, as well as general stress, so I'd estimate that the lower end of 2-4 days, though it could certainly be faster. Perhaps most cruel would be to offer or even force the consumption of water, which could extend this time period up to, again in "ideal conditions" as much as a few weeks, and possibly even longer with food, sterile conditions--i think I've said too much. Don't try it.68.171.235.139 (talk) 14:08, 4 April 2010 (UTC)[reply]

Note that in the story that is most familiar to us, the victim was given a wound in the side in order to make death come more quickly. Looie496 (talk) 19:17, 4 April 2010 (UTC)[reply]

My understanding of that particular story is that the victim had apparently died more quickly than was usual, and the wound was made to test whether death had actually occurred (as it had). The standard Roman procedure for hastening the death of a crucifixee was to break the lower legs, preventing them from taking body weight from the arms and thus bringing on suffocation (the usual cause of death, as per the answers below) more quickly. 87.81.230.195 (talk) 11:58, 5 April 2010 (UTC)[reply]

I must disagree with 68.171 about dehydration being the limiting factor for crucifixion survival time. This is because, when a person is suspended by his/her arms in a crucified position, the person's own weight puts an extreme stretching load on the muscles, tendons and ligaments in the arms/shoulders; this, in addition to causing excruciating pain, is also transmitted through the shoulders to the ribs, stretching the chest muscles and the diaphragm to the point where they cannot contract properly for exhalation. The victim must then haul himself/herself up and then forcefully contract the diaphragm and chest muscles in order to exhale (no easy task when the arm muscles are stretched out too), which leads to muscular exhaustion in a matter of a few hours at the very most. Once muscular exhaustion sets in, the victim can no longer force an exhalation, leading to death by asphyxiation long before dehydration becomes dangerous. FWiW the article mentions some people surviving crucifixion for up to several days, but I doubt it. 24.23.197.43 (talk) 01:55, 5 April 2010 (UTC)[reply]

that's also accurate, but it would depend on how a person was set and how their weight was supported. 206.53.157.72 (talk) 02:20, 5 April 2010 (UTC)[reply]

Normally, when someone was being executed by crucifixion, he/she would be tied or nailed to the cross by the wrists, with the arms stretched out to the sides -- this ensured that the stretching load would be transmitted to the ribs. If, on the other hand, someone was hanged by the wrists with the arms pointing straight up, this would not in itself be fatal, just excruciatingly painful and permanently crippling (which is plenty bad enough as it is). BTW, when St. Andrew was crucified, they hanged him on a cross that was X-shaped, so his arms were stretched up and outward at an angle -- would that be fatal by itself? 24.23.197.43 (talk) 05:44, 5 April 2010 (UTC)[reply]

Is there any plant, capable of being mown, that would stand up to be parked on by cars more than grass does? Thanks 89.243.36.35 (talk) 20:16, 2 April 2010 (UTC)[reply]

What you need is to put things within the grass like the link that follows this. a Sustainable Urban Drainage System. Basically a sort of cross-hatch rubber/plastic layer that grass can grow through (amongst other things) that allow the main weight of the vehicle to be carried by that, allowing the grass to flourish. - http://www.tensar.co.uk/contents.asp?cont_id=306&cont_type=3&page_type=CT ny156uk (talk) 21:21, 2 April 2010 (UTC)[reply]

(Just Added) Or Grass Pavers (search on google and you'll find loads of companies). ny156uk (talk) 21:22, 2 April 2010 (UTC)[reply]

Those rubber things look ugly, I've seen some. I'm still looking for some plant that is tougher than grass, and which will survive being mown. 78.149.194.146 (talk) 13:49, 3 April 2010 (UTC)[reply]

Try this. And google "high traffic ground cover" for more. Ariel. (talk) 01:10, 4 April 2010 (UTC)[reply]

The fist sentence says "These groundcovers don't take as much rough play as grass...". StuRat (talk) 13:51, 4 April 2010 (UTC)[reply]

I know. But a negative answer is still an answer. Ariel. (talk) 17:47, 4 April 2010 (UTC)[reply]

The trouble is that there are solid biological reasons why grasses make the best lawns.

The "surviving being mown" part is an interesting issue. The reason that plants of the grass family survive being mown is that they evolved to cope with grazing animals. The specific adaptation that they have is that - unlike other plants - the growth happens at the base of the plant instead of at the tips. With most plants, you mow off the growing tips and the plant can't renew itself so it just ages and dies. With grasses, the plant is renewed from the bottom - so you can keep on mowing it - and it'll just keep on growing. So right there - you're in trouble. You need grass (or at least something else in that family...um...bamboo? Probably not!

Sorry - but I'm pretty sure you need those pavers with the holes that let grass grow up between them. If you do find another plant, it'll be in the grass family. I don't think anything else will work. (Maybe astroturf?!)

SteveBaker (talk) 03:17, 5 April 2010 (UTC)[reply]

The problem is that cars compact the soil too much and make it hard for roots to penetrate. Graeme Bartlett (talk) 08:57, 5 April 2010 (UTC)[reply]

I've always joked that we should have chives as our lawn instead of grass. It seems that no matter how little attention they get or what horrible conditions they're put in they still flourish more than every other plant. Never tried mowing them, although they do stand up to being cut and used for potatoes pretty well. Your neighbors would hate you though; I'm sure the smell would be incredibly strong. -Pete5x5 (talk) 15:49, 5 April 2010 (UTC)[reply]

Things like dandelions and daisies survive being mown, so its not just grasses. 92.27.160.94 (talk) 09:45, 6 April 2010 (UTC)[reply]

is it possible to get pregant six days after the onset of mensturation (ie first day being last sunday 1, mon 2, tue 3, wed 4, thur 5, fri - today- 6). thank you. 82.113.106.100 (talk) 22:37, 2 April 2010 (UTC)[reply]

Incidentally, doing a search on one's user name, only to find a misspelled instance of the word "menstruation", is a distinctly unpleasant experience. :-) StuRat (talk) 13:39, 4 April 2010 (UTC)[reply]

Yes. See my answer below. Theresa Knott | token threats 23:35, 2 April 2010 (UTC)[reply]

It may be worth noting that home pregnancy tests are relatively cheap and quite accurate if you follow the directions carefully. Your doctor can conduct a more accurate test. Not to state the obvious, but... sex is kind of designed to make women pregnant. That's what it's for. You should always assume that a woman might become pregnant because she almost always can get pregnant. Matt Deres (talk) 00:02, 3 April 2010 (UTC)[reply]

*Sarcasm* See Evolutionary purpose of sex...aww, red link. =( Ks0stm ^(T•C•G) 00:09, 3 April 2010 (UTC)[reply]

WHAAOE - try Evolution of sexual reproduction...close enough. SteveBaker (talk) 02:10, 3 April 2010 (UTC)[reply]

No longer a redlink--Patton123 (talk) 12:50, 3 April 2010 (UTC)[reply]

When is a woman ready to concieve after menstruation period?reproduction in human being —Preceding unsigned comment added by KENNEDY NEWTON (talk • contribs) 23:29, 2 April 2010 (UTC)[reply]

It's not an exact science, (if it were people would be able to choose exactly when to get pregnant) but see our article Calendar-based methods for rough details. Theresa Knott | token threats 23:34, 2 April 2010 (UTC)[reply]

1. Whats the known cure for sinus? —Preceding unsigned comment added by KENNEDY NEWTON (talk • contribs) 01:25, 3 April 2010 (UTC)[reply]

The Paranasal sinuses are the large spaces between your nose and your throat. They aren't cured because they are not a sickness or disease. They are just big cavaties inside of your skull. Sinusitis is a situation when your sinuses become inflammed when you have a cold or have allergies like hayfever. Wikipedia is not the place to go for medical advice. You are free to read our articles about these topics, but if you are having sinus problems, see a doctor in person. They can help you. --Jayron32 01:40, 3 April 2010 (UTC)[reply]

Hey all. My bio prof said something the other day that I think wasn't quite right. Consider a baseball. If it has a velocity of 90 miles/hour west, and it was hit by a bat with 100 mph (east), how fast (east) would the ball move? The prof said 190mph, but how could it be greater than either speed? THX 76.230.145.252 (talk) 01:44, 3 April 2010 (UTC)[reply]

The reason is is because the heavy bat has a lot of energy swinging (as anyone who has been hit by one can tell you). When the heavy bat hits the relatively light ball, all the energy it took to move a heavy bat at 100 mph now goes into a ball that weighs a few ounces. It takes less energy to move the ball than the bat, so when the ball receives the same amount of energy that it took to move the bat, it goes much faster. --The High Fin Sperm Whale 01:49, 3 April 2010 (UTC)[reply]

This is how to think of it. If we assume that the bat and ball are part of an elastic collision (read that article), it means that the energy is conserved in the objects colliding. Certainly, a small amount of energy is lost (sound and heat mostly), but its not a bad approximation. If the energy of the ball-bat system is roughly the same before and after the collision, then almost all of that energy is part of the combined system is transfered to the ball. I'm not sure where the 190 mph comes from; energy should be additive, and not velocity, but yes, the ball SHOULD be moving faster by itself than either was moving before the collision. Since we assume elasticity, then the direction doesn't matter; energy can reflect and change direction just fine. --Jayron32 02:04, 3 April 2010 (UTC)[reply]

Both bat and ball have a little elasticity - so that much of the kinetic energy from the westbound motion of ball goes into bending the bat and deforming the ball. As the ball heads off in the opposite direction, both bat and ball un-deform - giving back much of that energy. Hence, the ball can leave the surface of the bat and get that extra 'kick' at the end. SteveBaker (talk) 02:05, 3 April 2010 (UTC)[reply]

Ok, I know that the ball is moving faster after the collision, even if only due to the difference in energy the ball has and the bat has. But where did my prof get 190? It seems like an arbitrary mathematical operation. If we set values for the masses of the ball and bat (let's call them x and y, respectively) how would we figure out how fast the ball was actually going after the collision? 76.230.145.252 (talk) 02:13, 3 April 2010 (UTC)[reply]

I'm assuming he simply added the 90 mph from the ball and the 100 mph from the bat, and got 190 mph (90 + 100). In general, you can't add velocities. While issues of special relativity only show up at really high speeds, you still can't do it at low speeds, because velocity is not the conserved quantity, momentum and energy are. (Even if velocity was conserved, it wouldn't be 190mph, as the bat still has forward motion after it contacts the ball.) I was going to mention the Galilean cannon as a cool demonstration that velocities are not conserved, but I can't seem to find reference on Google to the usage. As I recall it, it's a stack of steel spheres of increasing size dropped down a tube. When they hit the bottom, the smallest (top) sphere get almost all of the momentum from the stack (as in Newton's cradle) and goes shooting off. Is this actually called something else? -- 174.31.194.126 (talk) 02:42, 3 April 2010 (UTC)[reply]

I agree. The 190 mph does seem a bit random. It doesn't seem to have any basis in real calculations. What you would need to know is the speed of the bat, the mass of the bat, the speed and mass of the ball, and the amount of time they are in contact with each other in order to calculate how much energy is likely transfered to the ball. It would only be by a bizare coincidence if the ball leaves at exactly the sum of their velocities. You can do a simple experiment to show that velocity is not additive in this way. --Jayron32 02:29, 3 April 2010 (UTC)[reply]

Jayron, the contact time is neither necessary nor very useful. The coefficient of restitution is the extra piece of information required to solve that kind of problem. Dauto (talk) 02:54, 3 April 2010 (UTC)[reply]

This study takes into consideration bat speed, weight and coefficient of restitution. caknuck _° needs to be running more often 03:17, 3 April 2010 (UTC)[reply]

(edit conflict) Assuming an elastic collision, and ignoring the effect of the person swinging the bat, then the ball, from the reference frame of the center of mass, appears to enter and leave at the same speed before and after the collision (momentum and energy are conserved). If we approximate the bat as infinitely massive (or significantly large compared to the ball), then the center of mass reference frame is just the reference frame of the bat. In that case, the ball, from the bat's point of view, enters at 190 mph, and so must leave at 190 mph. Adding that to the bat's 100 mph, we get the ball traveling 290 mph in the stadium reference frame. That's obviously not a good answer (the collision's not elastic, the bat's not infinitely massive, etc.), but the 190 seems to come from nowhere as well. Buddy431 (talk) 03:30, 3 April 2010 (UTC)[reply]

Assuming the (lets say ~35 ounces (0.99 kg)) bat loses 10 m/s its velocity of 100 miles per hour (45 m/s) through the collision with the .145 kilograms (5.1 oz) baseball traveling at 90 miles per hour (40 m/s), then:

${\displaystyle .145\times -40+.99\times 45=.145\times X+.99\times 35}$

${\displaystyle -5.8+44.55=.145X+34.65}$

${\displaystyle 4.1=.145X}$

28.28 metres per second (63.3 mph) = the ball's final velocity? I think I need more help than the professor...what'd I do wrong here? If no one corrects this by morning, I'll get out my physics book and redo this. Ks0stm ^(T•C•G) 05:22, 3 April 2010 (UTC)[reply]

Why would you assume that? Dauto (talk) 06:44, 3 April 2010 (UTC)[reply]

The "Astro-blaster" is the modern version of theGalilean cannon that '174 mentioned above (which - surprisingly - isn't named after Galileo - but after the city of Galilee). I guess the original has a stack of balls inside a tube - the modern version has four balls threaded on a wire. Ranging from a large/heavy one at the bottom through consecutively smaller and lighter balls to a small one at the top. You drop this contraption so that the big ball hits the ground and the topmost ball will rebound with a spectacular amount of speed. So much so at they have to sell the gizmo with safety goggles! An even simpler way to demonstrate that "conservation of momentum" most certainly doesn't mean "conservation of velocity" is demonstrated in this YouTube video - which is essentially a Galilean cannon with just two balls. It's hard to believe that we don't have an article about this stuff - but it's tough to find details for anything other than the modern version. SteveBaker (talk) 16:35, 3 April 2010 (UTC)[reply]

(I created a Galilean cannon article...it could use some expansion). SteveBaker (talk) 03:07, 4 April 2010 (UTC)[reply]

Your 3rd ref just seems to be floating out in space. StuRat (talk) 03:13, 4 April 2010 (UTC)[reply]

Can I ask an unrelated question here? It may not be completely unrelated. Let us say a baseball is pitched fast — a fastball. Let us say a batter hits a powerful line drive off the fastball, almost directly back at the pitcher — let's say several feet over the pitcher's head. It is a very powerful shot and it is an out-of-the-park home-run. My question is: Is the ball ever at rest between making contact with the bat and sailing off over the pitcher's head? To phrase it differently: Does the ball's motion in one direction involve coming to a complete stop before embarking on its motion in virtually the opposite direction? Bus stop (talk) 03:30, 4 April 2010 (UTC)[reply]

This is a version of the fly-and-train paradox (it probably has a better name - but I don't know what it is). The idea is that there is a teeny-tiny housefly heading east along a railroad track which hits a train heading west. Since it seems obvious that there must be a moment when the fly goes from travelling at 10mph to the east to moving at 60mph to the west, there must be some moment at which the fly is stationary...but since it's in contact with the front of the train - then surely the train is also stationary at that moment! Why doesn't train react to hitting the fly in the same way it would if it hit a 500 ton, stationary, solid steel barrier?

The reason this isn't true (and the reason why we wouldn't say that the baseball was ever strictly speaking, "stationary") is because neither flies nor locomotives nor bats nor baseballs are perfectly rigid. So the object doesn't reverse direction instantaneously as a solid lump - it does it atom by atom. So it's perfectly possible for individual atoms to slow down, stop and the reverse direction without the entire object seeming to do so. At the necessary low level of visualisation, everything is very elastic and bendy. SteveBaker (talk) 04:14, 4 April 2010 (UTC)[reply]

Thank you for that response. Let me try to pose another question (or two). I'm not sure this question makes sense, but here goes:

If two atoms, or subatomic particles, collide, head-on, both of which are traveling in exactly opposite directions, both of which are of equal mass — how do they behave in ways relating to the collision? Do either or both of them reverse direction? Do either or both of them spend a duration of time at rest before resuming travel? Bus stop (talk) 11:03, 4 April 2010 (UTC)[reply]

At the atomic level, Quantum theory dominates what's going on and the simplistic ideas we have about large-scale objects like trains a baseball bats become fuzzy and uncertain. In particular, once you invoke quantum theory, it is meaningless to talk about a particle having both an exact position and an exact momentum because of the Uncertainty principle. Hence you cannot ask whether two atoms "collided" (meaning that their positions are known to be adjacent) and also know what their speed is. If you wish to talk about whether the atoms are stationary or not - then you can't talk meaningfully about their positions. At this level, atoms are fuzzy probability clouds that can't be pinned down enough for this question to even have meaning! This is an annoying final resolution to an interesting paradox - but that is how the universe works. SteveBaker (talk) 17:00, 4 April 2010 (UTC)[reply]

Surely a small amount of energy is also lost to the bat, batter and ground as vibrational energy, and some should also be lost from the ball as thermal energy due to the elastic friction and expansion of the ball during and after collision? And let's not forget about air resistance (and why is your biology prof teaching baseball physics?). ~AH1^(TCU) 23:18, 4 April 2010 (UTC)[reply]

What is the name of that feeling that one gets when their worst fears or suspicions are (actually, seemingly, or falsely assumed to be) realised? Thanks. ~AH1^(TCU) 02:26, 3 April 2010 (UTC)[reply]

Life. --Jayron32 02:29, 3 April 2010 (UTC)[reply]

A self-fulfilling prophecy ? StuRat (talk) 02:57, 3 April 2010 (UTC)[reply]

Dread seems about right to me. --Anonymous, 04:09 UTC, April 3, 2010.

Horror and terror seem close, as does fear itself at the resulting situation, and fight or flight response would be the associated physiological response. Ks0stm ^(T•C•G) 04:26, 3 April 2010 (UTC)[reply]

A sinking feeling? --TammyMoet (talk) 10:28, 3 April 2010 (UTC)[reply]

Concurred! Vranak (talk) 12:05, 3 April 2010 (UTC) [reply]

Amazement. If it is "worst fear" that is under consideration than "lowest likelihood" is a quality which is associated with that "fear." (The reason for this is that one doesn't normally go into situations which contain great likelihood of catastrophic failure, though I will admit this premise is dubious.) Therefore, in addition to the disappointment and horror that would likely accompany the realization that the worst possible outcome has indeed transpired, would be the irrepressible sensations of surprise and amazement.

As an example of this I find a brilliantly written line by E. Annie Proulx:

"She fought her way forward, seven, eight feet, her heart hammering, so intent on reaching the other side of the gully she felt only astonishment when the fatal aneurism halted her journey."

That is from Postcards (novel). Bus stop (talk)Bus stop (talk) 03:40, 4 April 2010 (UTC)[reply]

Please see RGB color range for human skin and the next three questions at Wikipedia:Reference desk/Computing.
-- Wavelength (talk) 06:02, 3 April 2010 (UTC)[reply]

I already have. And on the Humanities desk. Why do you think it necessary to post to so many reference desks? --Phil Holmes (talk) 11:59, 3 April 2010 (UTC)[reply]

It is commonly seen and experienced that general body aches and soreness feel better with simple massage. How does massage help with body aches and general soreness? Shivashree (talk) 07:11, 3 April 2010 (UTC)[reply]

When I trained as a masseuse, I was told it is partly due to the increased blood flow to the tissues brought about by the movements of the hands on the body, which breaks down things such as lactic acid and makes it easier for the blood to carry it away. It's also partly due to the relaxing effect of repetitive movements on the muscles and on the brain, and this relaxation restores equilibrium in the affected tissue. The heat generated by the friction of the massage will also relax the body. All this will stimulate the production of endorphins which are natural painkillers, and also produce a degree of euphoria. --TammyMoet (talk) 08:08, 3 April 2010 (UTC)[reply]

Plus, we are still monkeys, and grooming has its pleasures. --Ludwigs2 16:34, 3 April 2010 (UTC)[reply]

I was thinking of saying something like that but didn't bother, but you put it more succintly anyway. Of course it's unclear how much this will apply if we're referring to something like a massage chair with no other human involvement Nil Einne (talk) 17:26, 3 April 2010 (UTC)[reply]

well, massage chairs don't work nearly as well. it's something in the physical contact with others, I think. interestingly, in orangutans (or is it gibbons, I forget), the lead male in a troop is significantly larger and has a noticeably different coloration than beta males, and both the size and coloration differences have been traced to the fact that alpha males get much more grooming attention from females. It is not an insignificant behavior. --Ludwigs2 17:55, 3 April 2010 (UTC)[reply]

I think that the nerves that transmit pain, and touch are the same nerves. If you use the nerves to transmit touch they can't transmit pain at the same time, so you don't feel the pain. This is why rubbing a "boo boo" works so well for kids. Massage presumably does the same thing, but in deeper tissues. I think that once the pain sensation stops it doesn't start up again right away, or maybe the nerves get "exhausted" and don't transmit for a while. Ariel. (talk) 01:14, 4 April 2010 (UTC)[reply]

Can anyone provide me with some examples of animals which appear cute to humans but in reality have an extremely bad-tempered and violent nature? An encounter with someone's small, fluffy but hateful (even the owner agrees) little lap-dog yesterday got me thinking about this. --95.148.105.52 (talk) 08:17, 3 April 2010 (UTC)[reply]

If you want your living room rearranged, perhaps you can try these cute ones. DVdm (talk) 09:32, 3 April 2010 (UTC)[reply]

Wolverines could be cute. Staecker (talk) 11:44, 3 April 2010 (UTC)[reply]

Monkeys are often very cute and can be extremely violent, especially when they are protecting young. The Barbary Macaque (sometimes called "Barbary Ape", but it isn't an ape) springs to mind - they are known for ripping cars apart when they are driven through nature reserves. --Tango (talk) 11:46, 3 April 2010 (UTC)[reply]

Squirrels all seem to have bad attitudes, from the way they retreat up a tree, then "yell" at you. StuRat (talk) 11:48, 3 April 2010 (UTC)[reply]

If you've ever tried to give a kitty a worming pill you will know just how evil cute kittens can be! [7] --TammyMoet (talk) 12:11, 3 April 2010 (UTC)[reply]

Presumably one tries to force the pill down its throat? Not undue grounds for retaliation methinks! Vranak (talk) 15:01, 3 April 2010 (UTC) [reply]

Giant pandas are apparently a lot less cuddly than they look. For an extremely scientific take on this, here's a brief scene of one kicking Wolverine's ass. Matt Deres (talk) 12:49, 3 April 2010 (UTC)[reply]

Raccoons are considered by some^[who?] to be adorable, but they are 'savage' when cornered. That's from a 1970s Encyclopedia Brittanica account I read. Vranak (talk) 14:59, 3 April 2010 (UTC)[reply]

Meerkats come to mind. Lovely looking, eviiiiiiiil things. Regards, --—Cyclonenim | Chat  15:46, 3 April 2010 (UTC)[reply]

I've heard that even koalas can be rather testy at times. Deor (talk) 16:48, 3 April 2010 (UTC)[reply]

Depending on your definition of "cute" the hippopotamus might fit, but they are notorious for being territorial and dangerous. They may look docile, they're considered to be the most dangerous animals in Africa [8]. -- 174.31.194.126 (talk) 18:31, 3 April 2010 (UTC)[reply]

The Peach-faced Lovebird is a cute, fluffy little bird with large, soulful eyes, a legendary reputation for affection - and quite often a very short temper, backed up by a powerful bite (for its size). --Kurt Shaped Box (talk) 19:59, 3 April 2010 (UTC)[reply]

Captive Chimpanzees are notorious for "going bad". Cute baby chimps grow into terriotorial and mean-tempered adults that can tear your arms off of your body. Bad times. --Jayron32 21:09, 3 April 2010 (UTC)[reply]

The Red-fan Parrot (Deroptyus accipitrinus) looks amazing, but has an extreme temper. I heard of someone who walked into its cage and was attacked, and has to get stitches in his hand and lip. --The High Fin Sperm Whale 00:59, 4 April 2010 (UTC)[reply]

Oh, and let's not forget our most cute little polar bear. DVdm (talk) 09:21, 4 April 2010 (UTC)[reply]

It depends on how you define cute, but don't forget about dolphins and hippopotamuses which can be dangerous at times. And if you don't mind a slightly alarmist and doomsday-ish source: meow. ~AH1^(TCU) 22:42, 4 April 2010 (UTC)[reply]

Supposing someone in a small home or underground bunker had an unlimited source of electrical power,for example an atomic or renewable power source. Assuming some catastrophe occurred such as meteorite impact, atomic war or 28 Days Later zombies making going outside hazardous, what crops could be grown inside on racks for lets say 5 years using artificial lighting, hydroponics and total water/waste recycling to sustain a person without nutritional deficiencies? Or would it be practical at all in a small space?[Trevor Loughlin]80.1.80.25 (talk) 13:18, 3 April 2010 (UTC)[reply]

Read Biosphere 2 - an actual attempt to do something exactly like that (hint: It didn't work!). Even with futuristic technology, you'd need some really fancy chemistry. You can (in theory) use power to push chemical reactions 'uphill' to make compounds with enough energy to be useful foods (sugars, etc) - but humans need protein - and that's really complicated stuff to make artificially. So you're back to using energy to grow plants and that requires light, and water and CO2 - plus some more tricky nutrients like calcium - and you'd need a large amount of space - perhaps an acre per person. Light you could provide - water, you could recycle, CO2 you'd get from your own breath. The problem would be keeping everything in balance. Every drop of water would have be reclaimed - not just urine - but also sweat, tears, moisture in your breath. You'd have to carefully reclaim every ounce of unused plant material - all of your dead skin cells - if someone dies, their body has to be recycled. This is a monumentally difficult problem. When you see how badly things went wrong with "Biosphere 2" in much less than 2 years - you'll perhaps understand why this is so tough. The best chance your survivors have is to have a BIG pile of MREs and good water and air recycling - with enough air and water in reserve to cope with the inevitable losses over time. Even then - it's tough. SteveBaker (talk) 13:53, 3 April 2010 (UTC)[reply]

(edit conflict with below) Surely you can vent waste gasses to and draw air from the outside (filtering it, of course, for radioactive fallout, etc.) and water from a well (again, with appropriate purification), so that you don't need to be quite as careful with reclamation. It's still hard to grow enough food of course, but you wouldn't suffer the CO2 and O2 problems that biosphere 2 did. I'm not sure what types of crops are best for that type of thing. Presumably some sort of legume and grain for protein, and then some high calorie starchy food (potatoes, maybe?). Like Steve said, getting all the micronutrients would be hard, but it wouldn't be too hard to stockpile multivitamins for people to consume for 10 years or whatever (and takes considerably less space than enough MREs for everyone). Buddy431 (talk) 14:55, 3 April 2010 (UTC)[reply]

The failure of Biosphere 2 doesn't really tell you a whole lot. Much more sophisticated systems have been developed since then, and since the purpose is typically for space travel, they've been done in much smaller volumes. Plants can be tiered vertically and supplying them with adequate light isn't a huge problem. With the right mix of plant foods ,protein is not a problem. You said 5 years, so we can neglect recycling dead humans. That's not to say that there aren't daunting technical problems, especially if you want a totally closed system. My semi-informed view is this is totally possible with present day technology, but it is not easily do-it -yourself (although DIYers surprise us all the time). ike9898 (talk) 14:47, 3 April 2010 (UTC)[reply]

I'm also curious about what can be done with unlimited power. If you have connected into an outside wall a Super Special Outlet, from whcih you can draw any number of amps over any voltage (you specify the voltage with a separate connected keypad first), for example, you can set the voltage to the voltage of tension wires - our article says: "In electric power transmission engineering, high voltage is usually considered any voltage over approximately 35,000 volts". Obviously you have to be careful if you go from 35,000 volts to, say, 350,000 volts, as that potential difference could just arc across dry air. But say you could design a safe way to have a 10,000,000-watt "connector", and you were able to draw any number of amps over it, let's say you decide to draw 10,000 amps, giving you... 10,000 gigawatts. What could you do with that? Going further, apparently "the Sun pumps about 386 billion million gigawatts into space", so, if you were to have available all that energy (ie "386 thousand million million" or 386,000,000,000,000,000 Gigawatts), what could you do with it? How about, if, through some means (obviously we've long since stopped talking about a single power outlet, but a limitles array of them) you had access to all of the energy not just from one star but from every star, increasing the above number by a factor of 10^24, ie the above number * 1,000,000,000,000,000,000,000,000. If there is something your above 386,000,000,000,000,000 Gigawatts weren't enough for, surely 386,000,000,000,000,000,000,000,000,000,000,000,000,000 Gigawatts would be more than enough. So, in practical terms, what could you do with all that power? For example, could you even make a Star Trek style teleporter, or food replicator? (Recalling that, by any measure, they had access to FAR less than that amount of technology). Could you magically start producing enormous power of calculation, without having to build something special for it? What else interesting could you do? 84.153.209.78 (talk) 14:08, 3 April 2010 (UTC)[reply]

That Question's already been discussed, here. 80.1 is indicating a large, but not truly unlimited power source to be used for day to day living and growing crops. Buddy431 (talk) 14:45, 3 April 2010 (UTC)[reply]

... and having more than a few kilowatts available would not be an advantage in a small bunker because it would be impossible to get rid of the waste heat inevitable in any use of power. Dbfirs 20:15, 3 April 2010 (UTC)[reply]

I noticed that on one of my things there's no recyling symbol (as arrows), but an iconic man throwing a piece of paper to bin. What does this symbol mean? 83.31.117.108 (talk) 14:31, 3 April 2010 (UTC)[reply]

I think that symbol means, 'please don't litter'. ike9898 (talk) 14:48, 3 April 2010 (UTC)[reply]

'please don't litter'? Are you sure? 83.31.103.127 (talk) 18:09, 3 April 2010 (UTC)[reply]

If it's not "please don't litter" it could be "dispose this item properly." WHat is the item? — Ƶ§œš¹ _{[aɪm ˈfɹ̠ˤʷɛ̃ɾ̃ˡi]} 21:39, 3 April 2010 (UTC)[reply]

Cat's food. [9] The top is made of metal, while the rest is plastic, I think. 83.31.103.127 (talk) 22:05, 3 April 2010 (UTC)[reply]

I would assume that the manufacturer doesn't believe that the item can be recycled and therefore is prompting you to throw the container away instead of littering. I have no idea why it wouldn't be recyclable though. Dismas|^(talk) 00:26, 4 April 2010 (UTC)[reply]

That's a pity. My cat eats around 3 a day, so I thought I could put these to the recycling bin. 83.31.93.6 (talk) 10:52, 4 April 2010 (UTC)[reply]

If you're talking about the pouches, apparently they're a sort of amalgam of plastic and a metallic substance, which is currently unrecyclable. (This is what I was told by the recycling department of our local UK council, anyway) --TammyMoet (talk) 14:10, 4 April 2010 (UTC)[reply]

I think the OP is referring to something like this [10] (yes I appreciate this is dog food but Sheba who evidentally were the cat food equivalent don't exist anymore) or [11] (left not right). I did come across [12] which may be of interest Nil Einne (talk) 15:31, 4 April 2010 (UTC)[reply]

Yep, I mean these [13] What is funny, I had bought my cat similar food but of another brand/manufacturer, and found on the bottom of the package this symbol. 83.31.118.222 (talk) 15:43, 4 April 2010 (UTC)[reply]

A quick search on Google Images tells me that the sign means "Keep this area litter free", but that it isn't very widely used. Looie496 (talk) 19:08, 4 April 2010 (UTC)[reply]

I caught this lizard in my back yard in Houston, Texas. It could be native or an escaped pet. Can anyone tell me what it is and what we should be feeding it? Tobyc75 (talk) 16:04, 3 April 2010 (UTC)[reply]

I vote for the anole lizard, and, in particular, the Carolina anole. Contrary to the name, they are also native to the gulf coastal plain of Texas. The pic here implies that they eat moths, and also warns that they have a painful, but not poisonous, bite: Carolina_anole#Behavior. StuRat (talk) 16:26, 3 April 2010 (UTC)[reply]

The first article above contains this text about their diets:

"Anoles thrive on live insects and other invertebrates, with moths and spiders being some of the most commonly consumed prey. Anoles are opportunistic feeders, and may attempt to eat any attractive meal that is small enough. The primary foods for captive anoles are small feeder crickets that can be purchased at most pet stores."

StuRat (talk) 16:42, 3 April 2010 (UTC)[reply]

I'll second that. I live in North Carolina, and I usually have several of these guys roaming my yard on any given summer day. They will change their skin color from green to brown, which can be fun to see. But year, that's an Anole. They're endemic to all parts of the American south. It's probably not an escaped pet, its probably just around. --Jayron32 21:07, 3 April 2010 (UTC)[reply]

Does anybody know where I could find information about the companies that produce the lactic acid bacteria used to make cheese?--160.36.38.135 (talk) 16:06, 3 April 2010 (UTC)[reply]

What kind of information? If you're just looking for sources of bacterial cultures, a simple Google search for cheesemaking supplies will guide you to a great number of suppliers. Deor (talk) 16:41, 3 April 2010 (UTC)[reply]

I'm sorry, I should have been more specific. I am looking to learn about the large scale wholesale distributors.--160.36.38.135 (talk) 16:51, 3 April 2010 (UTC)[reply]

I'm still not sure exactly what sort of information about these companies you're looking for. A list of some such firms, linked to their Web sites, can be found here. Deor (talk) 18:30, 3 April 2010 (UTC)[reply]

That's a good starting point for me. Thanks.--160.36.38.135 (talk) 18:40, 3 April 2010 (UTC)[reply]

is it ok to lay a fridge on its side? —Preceding unsigned comment added by 66.128.217.54 (talk) 21:21, 3 April 2010 (UTC)[reply]

Yes, for transport. But make sure to let the fridge rest in an fully upright position for at least three(?) hours before plugging it in again. At least old fridges have a nasty habit of catching fire if you start it up (plug it in) again too soon after it has been tilted!
--Seren-dipper (talk) 22:23, 3 April 2010 (UTC)[reply]

What would make an old fridge start on fire after having been on its side?! Dismas|^(talk) 00:21, 4 April 2010 (UTC)[reply]

I would imagine that having the coolant in the wrong place is the problem. StuRat (talk) 01:31, 4 April 2010 (UTC)[reply]

No, not quite, it has nothing to do with the freon. The compressor is full of lubricating oil. It is very viscous, and if you put the 'fridge in the wrong position, it will not lubricate some parts of the motor, and it will overheat, just as if you ran a car engine without oil. --hacky (talk) 04:28, 4 April 2010 (UTC)[reply]

Anecdotally, an old refrigerator that has been transported on its side and then turned upright and turned on may fail quickly because of metal filings from wear which have not had time to migrate back down to the lowest point. It is folk wisdom I have heard for years, and an old refrigerator I sold to someone failed when they got it home, stood it upright and immediately turned it on. When I have moved an old refrigerator or freezer, I have given it a few hours before turning it on. I have not taken this precaution with new ones. It would be good to check the installation instructions and see if there is any caution regarding new ones. See also [14] regarding the oil issue with laying it on its side. Edison (talk) 19:45, 4 April 2010 (UTC)[reply]

I've begun to notice that when I eat things containing (what is shown in the list of ingrediants as) cinnamon, I feel depressed later. Or at least painful memories from the past make themselves known. Is there any known reason for this?

Two things which cause this are Twinings Chai tea (I have never had any other brand of chai tea) and mixed spice. They both contain cinnamon. Yes, I have read the cinnamon article, so I already know that a lot of what is described as cinnamon is actually cassia.

You might claim that this was due to the nutmeg, but as far as I know Twining's Chai tea does not contain any nutmeg. Thanks. 89.243.37.199 (talk) 22:38, 3 April 2010 (UTC)[reply]

The sense of smell is known to be very evocative in the stimulation of memories and emotions -- much more so than other senses. However, in aromatherapy cinnamon is listed as stimulating, even being listed as a pain reducer and antidepressant [15]. As it is a frequently used spice in desserts such as apple pie, it is also frequently associated with "hearth and home". If you are concerned that cinnamon is making you depressed or bringing up painful memories from the past, I would recommend contacting a qualified mental health specialist. Random people from the internet are not qualified to assist you in medical diagnoses. -- 174.31.194.126 (talk) 00:46, 4 April 2010 (UTC)[reply]

Aromatherapy is nonsense and considered by many including myself to be only for fools, cranks, and charlatans. The effects only occur some hours after ingesting the stuff so the smell has got nothing to do with it. 78.149.241.120 (talk) 10:21, 4 April 2010 (UTC)[reply]

Cinnamon is only ingested in very small quantities, so if it is true that it contains a compound which induces depression, it must have a high bioavailability, cross the blood-brain barrier very readily and have a very high affinity for wherever it is acting. This seems unlikely; are you sure it isn't a nocebo effect? How long did it take until you pinned the "source of depression" as cinnamon? --Mark PEA (talk) 10:41, 4 April 2010 (UTC)[reply]

I agree - Aromatherapy#Efficacy makes it quite clear that only the most tenuous evidence is available in support of what is quite clearly pseudoscience. The people who provide it are charlatans and the people who use it are engaging in wishful thinking. Oh if only we could cure diseases by sitting around smelling nice things instead of all of that complicated science stuff with expensive doctors and complicated chemicals. Well, sorry, but lovely though that sounds, it's just premium-grade bullshit that's up there with perpetual motion and the flat earth theory. SteveBaker (talk) 16:48, 4 April 2010 (UTC)[reply]

Well, at least it is premium-grade bullshit. It could be worse. It could be cheap bullshit. Dauto (talk) 18:25, 4 April 2010 (UTC)[reply]

Basically yes, but some essential oils may function as drugs (my rationalist, James Randi-admiring chemist friend is sure that roman chamomile sends him quickly to sleep), and also perfumes are a popular and uncontroversial way of using essential oils to affect people psychologically. They don't have very specific or reliable results, but if a perfume can make somebody think you're vaguely nice, I can't see why a different smell shouldn't make a person think he is vaguely unhappy. FWIW, though, I have a bottle of cinnamon essential oil which I put on the burner now and again to cheer me up (I only have three oils, and it's my favourite). It usually helps, although last time I did this the whole thing caught fire, which raised my anxiety level somewhat. 81.131.62.171 (talk) 03:00, 5 April 2010 (UTC)[reply]

It's always hard to rule out idiosyncratic effects in individual people. There is some evidence that cinnamonium cassia has anti-anxiety effects in high doses (see PMID 17512974), but I didn't see any mention of mood-lowering effects. Looie496 (talk) 19:00, 4 April 2010 (UTC)[reply]

Steve et al, while I agree there are very few rigourous scientific studies available confirming the efficacy of aromatherapy, every time you (or someone else) inhales Olbas oil when you have a cold, you are confirming its use for yourself! --TammyMoet (talk) 19:22, 4 April 2010 (UTC)[reply]

How do i prolong ejaculation without using drugs? —Preceding unsigned comment added by KENNEDY NEWTON (talk • contribs) 23:14, 3 April 2010 (UTC)[reply]

See Wikipedia:Reference desk/Science#Role of the Pudendal Nerve in male sexual function?, above, where TammyMoet alludes to a technique involving pressing on the perineum. I assume you actually mean "delay ejaculation" rather than "prolong" — I don't think there's any technique that prolongs the act of ejaculation. Comet Tuttle (talk) 00:03, 4 April 2010 (UTC)[reply]

That link doesn't seem to be working for me. Vranak (talk)

It was just archived. Try: Wikipedia:Reference_desk/Archives/Science/2010_March_30#Role_of_the_Pudendal_Nerve_in_male_sexual_function.3F. That's the permalink. StuRat (talk) 02:45, 4 April 2010 (UTC)[reply]

i read somewhere that frogs have an extended orgasm for almost 3 hours- so maybe thats what the OP wants;))) a prolonged ejaculation, jokes apart comet tuttle is absolutely right - while there are medications to prolong the act and delay ejaculation/ prevent the ejaculation reflex - there are no known medications to prolong the actual process of ejaculationFragrantforever 09:53, 4 April 2010 (UTC) —Preceding unsigned comment added by Fragrantforever (talk • contribs)

I just uploaded this photo of an Anole (I think), which was observed in a residential area in Guadeloupe. There are lot of these individuals around the place, also green ones like this Anolis marmoratus or Leopard Anole. The green ones and the grey ones like these seem to interact and they look very similar disregarding the coloration, so I was wondering if the more boring looking individual (who also lost its tail) is just the opposite gender? Possibly the female? --Slaunger (talk) 01:16, 4 April 2010 (UTC)[reply]

Where can I find a list of calories burned per hour of all different types of activity? 71.100.3.207 (talk) 02:45, 4 April 2010 (UTC)[reply]

Here's one: [16]. Here's another: [17]. StuRat (talk) 02:50, 4 April 2010 (UTC)[reply]

Let a pulse of light and spaceship/ train are moving perpendicular to each other such that after sometime the same pulse of light

Strikes and enters spaceship/ train through its one longitudinal side

Travel inside spaceship/ train for some time and then

Leaves the spaceship/ train through its other longitudinal side

Thus are such postulates holds true in abovementioned scenario 68.147.38.24 (talk) 04:29, 4 April 2010 (UTC)khattak#one-420[reply]

Yes. The observed lightspeed depends neither on the velovity of the sender, nor on the velocity of the receiver, nor on the direction of the light beam. 213.49.88.115 (talk) 05:39, 4 April 2010 (UTC)[reply]

The answer to the question may well depend on the country, but what kind of surgical training do doctors have when they get their first professional degree in medicine? In practice, what kind of surgical procedures can a non-specialist doctor with such training handle competently? —Preceding unsigned comment added by 173.49.14.137 (talk) 04:41, 4 April 2010 (UTC)[reply]

Don't know for sure. Recently qualified doctors will probably have decent knowledge of certain surgical procedures, but that doesn't mean they're qualified to perform them. As you said, it will depend on the country you qualified in. For example, in the UK, you graduate with your first degree in medicine then you will train further through specialist posts in the NHS. It's at these posts you learn the vast majority of your surgical knowledge, but I think it's pretty much up to you and how much you know and how much trust your supervisors place in you. They may allow you to perform complex procedures if they've observed you doing other simpler ones perfectly, and they're willing to supervise you. There is an exception, though. GP's in the UK can perform minor surgical procedures, but I'm not sure whether these are learnt during GP training, or whether the knowledge is gained through the first degree. Regards, --—Cyclonenim | Chat  17:42, 4 April 2010 (UTC)[reply]

If the question "what kind of surgical procedures can a non-specialist doctor ... handle competently" relates to doctors who qualified more than a year ago, then the simplest answer would be "none, unless they've had specific training since qualification". Having said that, it will also depend on the individual, their inclination and their experiences at medical school. When I qualified as a doctor in England ten years ago (and I don't think the situation has changed significantly), newly qualified medical graduates were expected to be able to take blood samples and insert an intravenous cannula without further training, some but not all could suture simple wounds, but anything beyond that depended on further training after qualification -- bearing in mind that most doctors work in a surgical team for a few months during their first year after qualification, and some gain quite significant experience of operative surgery during that time. Surgical skills decline rapidly if not practised regularly. Neurotip (talk) 22:12, 4 April 2010 (UTC)[reply]

Does any one have a significant number for this velocity, (or is its average along the orbit)?--Email4mobile (talk) 06:00, 4 April 2010 (UTC)[reply]

It's about 586 km/h. Dauto (talk) 06:14, 4 April 2010 (UTC)[reply]

• It seems to be much less compared to the orbital speed which is about 3679 km/h, Dauto, doesn't it?.--Email4mobile (talk) 10:33, 4 April 2010 (UTC)[reply]

I don't know where Dauto got that figure. The tangential velocity (I'm assuming you mean the speed along the tangent to its orbit at its location) will be exactly equal to its orbital velocity. That's how velocities along paths works - the object is always moving in a direction tangential to the path. If you mean the transverse velocity, that is the velocity along a line perpendicular to the line joining the centres of the Earth and Moon, then it will be almost exactly equal to its orbital velocity, but very slightly different because the Moon's orbit is slightly eccentric, that is not a perfect circle (but it is close). --Tango (talk) 13:35, 4 April 2010 (UTC)[reply]

I'm sorry. I dropped a factor from my calculation yesterday. The correct value is about 3680 km/h. Dauto (talk) 14:29, 4 April 2010 (UTC)[reply]

Thanks Tango and Dauto. I was thinking that tangential velocity is angular velocity which would be one component of the orbital velocity, whereas the radial velocity would be the the 2nd component.--Email4mobile (talk) 16:47, 4 April 2010 (UTC)[reply]

Ok, so you did mean transverse, not tangential. Transverse velocity is angular velocity times radial distance. For a circular orbit, all the velocity is transverse. The Moon's orbit is almost circular, so the vast majority of the velocity is transverse. The average radial velocity is going to be zero, since the orbit is periodic so any increase in radial distance at one point in the orbit much be balanced by a decrease elsewhere so you can get back to where you started. More interesting values would be the average radial speed (the absolute value of the radial velocity) and the maximum radial speed. I'm not sure what those are for the Moon, and it would take me a while to work out the formulae, so I'll leave this question for a bit in the hope that someone else can help more easily than I can! --Tango (talk) 16:58, 4 April 2010 (UTC)[reply]

I do mistakes frequently, thanks Tango ;).--Email4mobile (talk) 17:15, 4 April 2010 (UTC)[reply]

Is Finasteride a topical medicine for male pattern baldness or is an oral medication??? —Preceding unsigned comment added by 119.235.54.67 (talk) 08:48, 4 April 2010 (UTC)[reply]

Oral. Ariel. (talk) 09:02, 4 April 2010 (UTC)[reply]

The topical medication is Minoxidil. Zain Ebrahim (talk) 20:10, 4 April 2010 (UTC)[reply]

What's the difference between kinetics, dynamics, and mechanics? They all seem to be pretty much the same. 173.179.59.66 (talk) 08:59, 4 April 2010 (UTC)[reply]

Disambig: Kinetics (physics), Dynamics (physics). From the kinetics article: "Since the mid-20th century, the term "dynamics" (or "analytical dynamics") has largely superseded "kinetics" in physics text books". Mechanics includes dynamics, plus more. Dynamics is mainly Newton's laws. Mechanics seems to include pretty much everything, click on the image for more details. Ariel. (talk) 09:07, 4 April 2010 (UTC)[reply]

Does eating Egg(chicken) generate heat in our body?? It is disastrous in summer I think..... —Preceding unsigned comment added by 119.235.54.67 (talk) 09:20, 4 April 2010 (UTC)[reply]

Any food will generate heat in the body when it is metabolized. Eggs are unlikely to be different in that respect.

If you're asking whether chicken eggs contain something that will disturb the body's temperature regulation, then I've never heard about that. Raw eggs may contain bacteria that can infect you and cause a fever, but that's a different story. –Henning Makholm (talk) 10:26, 4 April 2010 (UTC)[reply]

Yes, exactly. Thank you! This is the perfect answer - and should have ended this thread right here. SteveBaker (talk) 16:34, 4 April 2010 (UTC)[reply]

Eggs are relatively easy to digest, so that would limit the amount of heat produced during digestion. Also, eating chilled eggs will, of course, cause you to heat up less than hot eggs. StuRat (talk) 13:27, 4 April 2010 (UTC)[reply]

While that's technically true - it's quite utterly negligable - and besides, the human body has thermo-regulation, if some kind of food did produce a tiny temperature increase for some bizzare reason, the body would simply cut back heat production to compensate for that. So please let's not start off another "old wives tale" that causes a bunch of people to eat their eggs cold in warm weather just because someone felt in need to have something to say!

The correct answer for our OP is:

"No, you are incorrect. Eggs cause neither more nor less heat to be produced in the body than other kinds of food."

Getting into these kinds of detailed technicalities does not serve to provide a clear and useful answer to a very simple question. SteveBaker (talk) 16:31, 4 April 2010 (UTC)[reply]

Yes, the human body can thermo-regulate, within a certain range. However, some of the mechanisms for doing so may be objectionable, such as sweating to cool the body and shivering to warm it. Drinking warm or cold fluids is a good way to regulate the body temp when you are feeling just a bit hot or cold, and prefer not to shiver or sweat. (Putting on a sweater is another way to keep warm, of course.) If you do the math, drinking water 60 degrees F below body temp, with a mass 1% of your body mass, should lower body temp by 0.6 degree. That's a huge shift in core body temp, and more than enough to prevent sweating, in many cases. Now, since you're probably not going to eat 1% of your body mass in eggs, the effect is somewhat less, but still significant. The heat generated by digestion may well be more significant, but note that this effect will start gradually, while the actual temperature of the food you eat has a more immediate effect. So, if you are hot now, eat or drink something cold. When the heat from digestion kicks in, hopefully you will be inside in an air conditioned room. If not, then you'll sweat. StuRat (talk) 16:44, 4 April 2010 (UTC)[reply]

That may be what happens if you do the math - but I'm not likely to start off with assumption that people (average body mass ~80kg) is going to drink 0.8 liters of water thats just a few degrees above freezing! A typical 'large' chicken egg weighs 50grams. So not 1%, not even 0.1% of body mass and the effect isn't just "somewhat less" - it's an order of magnitude less...and that assumes you're consuming the egg at 60 degrees over body temperature...which is unlikely. This "heat of digestion" is also very small - digestion is an energy-efficient process - it produces vastly less heat than the food itself provides. An egg contains about 300kJ of 'food energy'- but only the smallest fraction of that is produced as heat during digestion. Sweating is one of the body's last defenses against overheating. The first effects are for the mitochondria to reduce conversion of fats and carbohydrates - then blood vessels expand towards the surface of skin to shed heat that way - and only then does sweating kick in - finally, and ONLY after all of those mechanisms fail, will your "body heat" change - which is what the OP asked. The additional heat of digestion from an egg is scarcely likely to do much more than trigger the first of those cooling mechanisms unless the body is already working hard to lose heat. Besides, the issue here is not "Do I eat an egg or do I eat nothing at all?" - it's more like "Do I eat an egg or do I eat something else?" - and if that is the question then the answer is, again, a very clear "NO!" because the heat produced in digesting pretty much any food is going to be very similar. So why are you working so hard to confuse the OP with highly dubious arguments when the answer is so very simple? If you eat an egg - your body temperature won't change to any measurable degree...period. SteveBaker (talk) 17:55, 4 April 2010 (UTC)[reply]

1) You can't drink 0.8L of cold water ? I certainly can, as can many people.

2) Why do you assume the person will only eat a single egg ? I can certainly eat several, as can many people.

3) If the heat of digestion is low, then the temperature of the egg is even more significant, by comparison.

4) It certainly seems likely that they are already hot, if they are worried about getting hot from eating eggs. Thus, they may be just about to sweat, or may even be sweating already. So, every little but counts, if they want to keep from sweating more. StuRat (talk) 02:14, 5 April 2010 (UTC)[reply]

It certainly seems likely that they are already hot, if they are worried about getting hot from eating eggs - I'm not so sure about that. When I original saw the question removed for medical advice by the same OP, my first thoughts were similar to 206, the OP was referring to the concept of heaty food as described e.g. [18] oh and look I found an article Chinese food therapy. Then I saw the IP looked up to India so I wasn't so sure since I was aware of Chinese concept (it's not uncommon in Malaysia) but not sure that it had an India counterpart (I did search but didn't come across anything useful, the Ayurveda article for example only makes one irrelevant reference of heat).

206 suggests a similar concept in India and in fact looking more closely, I found at least one ref more when I connect it to Ayurveda as 206 suggest [19]. I'm not so sure how the Ayurvedic concept works, heck not even that familiar about the Chinese concept but I wouldn't presume someone being worried about 'heaty' or 'heating' foods is necessarily feeling hot they might just be worried generally because of their belief in the concept. (Balance is of course an important component of the belief, if you eat too many heaty foods like durian you're supposed to eat cooling foods like mangosteen.)

Nil Einne (talk) 03:04, 5 April 2010 (UTC)[reply]

Some people have food allergies with eggs, you might be one of them. Also traditional medicines like chinese medicine and indian ayurveda have for thousands of years described certain foods and other substances as "cooling" or "warming". I don't think modern science recognizes these effects, but then again many things have not been recognized by modern science that may still have merit. 206.53.153.184 (talk) 14:32, 4 April 2010 (UTC)[reply]

Another useless answer to a simple question!

• Firstly: Allergies don't cause your body temperature to go up or down - please don't guess when you provide answers here: Allergic_reaction#Signs_and_symptoms has no mention of body temperature change and fever is very clear that this is the body responding to infection. You are thinking of infections causing fever and that's an entirely different matter. Furthermore, you are diagnosing a medical condition and that's not allowed on the Wikipedia reference desks.
• Secondly: There are vastly more ancient claims that turn out to be worthless (or perhaps even dangerous) nonsense than there are scientific claims that are eventually overturned by ancient knowledge. This is undoubtedly a case where the "traditional medicine" answer is 100% incorrect. Look at it this way: If you have to make a decision, by far your best chance to make the best chooice is to go with modern science and ignore all of that ancient/traditional junk.

Please - can't we just answer a simple question with a simple, science-based answer? SteveBaker (talk) 16:31, 4 April 2010 (UTC):[reply]

I think your presumption that I hate science blinds you here. Allergic reactions produce histamines, as well as increases in blood pressure heart rate, adrenaline, and cortisol. These are all highly warming, and could raise the sensation of body temperature if not produce an actual fever.

While many traditional cures are bunk, many have also been incorporated into modern medicine, and you well know that natural substances found in plants, fungi, and bacteria are the overwhelming inspiration for biochemical research. Ancient traditions stumbled upon some of these by accident and cultivated a holistic theory of medicine around them. Which ones are valid and invalid remains open to further research. Skepticism does not preclude, and indeed it benefits from a curiosity about historical practices.

Finally, the actual biochemistry of digestion as well as the absorbtion of nutrients through the stomach, intestines, blood, and cells, as well as the interaction of nutrients and organic matter with enzymes in the body is a phenomenally complex process that we don't have a full scientific understanding of yet. So why not consider another source, albeit anecdotal.

Also, hating on wikipedia makes it not fun, so maybe don't do it?68.171.233.151 (talk) 17:50, 4 April 2010 (UTC)[reply]

Nobody said anything about hating - and I have no idea about whether you hate science or not. However, giving wildly incorrect guesses to legitimate questions is indefensible...and when you do that, you will be called on that. I'm not about to let people tell untruths to our questioners. The references desks are not about having fun - they are about producing factual answers to serious questions - and if you think otherwise, then you're in the wrong place. So, if you intend to continue to give misleading answers, maybe you are the one that should "maybe don't do it".

Anecdotal answers are also unacceptable here - except, perhaps, to serve to better explain a properly referenced fact. WP:NOR applies here - and so, no - we aren't going to "consider another source, albeit anecdotal" because that would be contrary to the rules, and again, if you think that's acceptable, then you're in the wrong place.

Certainly there are cases where 'traditional cures' happen to work - but there is zero methodical process involved in them. Science has researched many of them - and the ones that turn out to have a basis in fact become a part of the scientific canon. Nobody is denying that substancs in plants, fungi and bacteria are biologically active - it would be exceedingly surprising if they were not! However, random application of biologically active substances holds as many dangers as it does opportunities...which is precisely why we need to take a scientific approach to investigating them.

At any rate, we aren't being asked about some complicated, untested traditional cure. We're being asked a very simple question about an exceedingly well-researched subject of thermoregulation (and homeothermy in particular). This is well understood, established science - and 'traditional' views are simply irrelevant.

SteveBaker (talk) 18:18, 4 April 2010 (UTC)[reply]

For clarification, are you 206.53.153.184? Nil Einne (talk) 19:49, 4 April 2010 (UTC)[reply]

if you drop the science vs. Idiots dichotomy, you'll see that my response adressed the questioner's personal experience which, by "disastrous" was clearly not a merely technical question about thermal regulation/metabolism but about the op's personal experience of how the digestive process and its aftermath made him or her feel. Allergies are not magic and science has ample explanation for them.

as for traditional medicines, they're interesting historical, cultural, alternative explanations. They don't offer proof but they might be useful for confirmation or as starting points for further research. Surely people might do some useful things that science has not yet tested. Even old practices evolved through processes of experimentation, though not up to modern standards. Further, my post didn't suggest those as "answers", just references, places to look for further research, which is what we do here. Its not original research in any way to link to pages which exist! on wikipedia and address the topics of egg allergies, and traditional categorizations of the effects of food.

in other words, its not original research just because you don't like it, aren't interested in it, or discount it entirely. Readers benefit from a variety of opinions and a discourse about them. I'm not equivocating between science and ayurveda, but there's no reason not to mention a millenia-old cultural belief if it has some relevance. Let the reader see what it says and take whatever insight there is to take.

calling answers useless and decreeing that because many traditional practices haven't stood up to scrutiny (implying that others have) and are therefore irrelevant is kind of hating. They're relevant because they offer another viewpoint on the subject, explicitly. The wikipedia reference desk can mention areas within the entire encyclopedia, even if they're outside the scope of a particular sub-page. And just because a field of science has an answer, it doesn't mean that no other information would be relevant. Wikipedia seems more fun when people aren't so critical of responses that attempt to add to the discussion, fun including bot usefulness and enjoyment.

Ips 68 and 206 are floating cell phone ips, both mine.206.53.157.72 (talk) 02:35, 5 April 2010 (UTC)[reply]

My dogs found, much to their entertainment, a muskrat under a trailer next to my garage. I've read our article and poked around a bit. What I'm wondering is if I need to worry much at all about my chickens being killed by the muskrat. I realize that they're omnivores but is there much need for concern?

For what it's worth, I live on a mountain with some swampy areas along side the road a little ways, roughly 150 - 200', down the road from me. I suspect that's where it has been living. I'm at a loss as to why it would come up the road to my house as the only water near my place is a small spring I have next to my driveway. I'm at the top of the mountain, so everything drains away from my place. Thanks, Dismas|^(talk) 09:54, 4 April 2010 (UTC)[reply]

I'm pretty ignorant about muskrats, but if it's just the word "omnivore" that worries you, it shouldn't. Usually that just mean an animal that will eat critters small enough for it to swallow if it gets the chance. Actively hunting and dismembering prey of your own size tends to demand adaptations that the guy pictured at muskrat does not appear to have. Indeed, the article says:

Plant materials make up about 95 percent of their diets, but they also eat small animals such as freshwater mussels, frogs, crayfish, fish, and small turtles.

It's a far reach from that to chickens. Worry about the fox and the hawk instead. –Henning Makholm (talk) 10:43, 4 April 2010 (UTC)[reply]

I'd say the adult chickens are pretty safe, but maybe not the eggs or chicks. He probably is living under the trailer because that's a nice ready-made home for him. To get rid of him, you might want to eliminate this home, by putting the trailer on it's side, for example, so there's no space underneath it. StuRat (talk) 13:25, 4 April 2010 (UTC)[reply]

Thanks for the reassurances. I doubt he'll stay/come back to live under there. With four dogs, we don't get much wildlife in the yard to begin with, so one taking up residence is fairly unlikely. The biggest problems that we've had with animals killing our chickens have been from an ermine who would take them out in the middle of the night and from a wolf or fox. We were out of town and the dogs were with us when the wolf/fox came that time. Dismas|^(talk) 21:44, 4 April 2010 (UTC)[reply]

As for why he went roaming, maybe it's mating season and he's looking for a g/f ? StuRat (talk) 02:04, 5 April 2010 (UTC)[reply]

How far does a muskrat ramble during mating season? Edison (talk) 02:40, 5 April 2010 (UTC)[reply]

Light cannot go faster than the speed of light. But what about a universe where planets and stars are whizzing around choatically at near the speed of light in all directions. How does the light know which frame of reference to choose? Depending on the choice of the reference frame, the light may appear to be going very slowly, too fast, or even backwards. 78.149.241.120 (talk) 10:26, 4 April 2010 (UTC)[reply]

That's the wonder of special relativity and the Lorentz transformation. Light doesn't have to "choose" a preferred frame of reference. The speed of the light is the same relative to every inertial frame of reference, thanks to time dilation, length contraction and the relativistic velocity-addition formula. Gandalf61 (talk) 10:35, 4 April 2010 (UTC)[reply]

A minor correction, gandalf. The speed of light is the same relatative to all reference frames, including inertial and non-inertial ones. Dauto (talk) 17:20, 4 April 2010 (UTC)[reply]

A minor correction, Dauto, ...including inertial and non-inertial ones when locally measured :-) - DVdm (talk) 17:29, 4 April 2010 (UTC)[reply]

We also could say that the speed of the light is the same relative to every inertial frame of reference, hence time dilation etc...

Originally special relativity started with the invariant speed of light and decuced dilation, contraction, addition and transformation from it. We don't really know what causes what. We just know that the speed is invariant - not why it is. DVdm (talk) 10:44, 4 April 2010 (UTC)[reply]

And for the original experimental evidence that the speed of light is invariant, see Michelson–Morley experiment. –Henning Makholm (talk) 10:53, 4 April 2010 (UTC)[reply]

It runs completely against "common sense" - but light is weird stuff. No matter how you are travelling and no matter how the source of the light was travelling - the speed that you measure is always exactly the same. So even in your chaotic universe, the light never appears to be travelling at anything other than the speed of light - no matter which reference frame you are in. In a sense, light "chooses" all of the frames of reference at once! SteveBaker (talk) 17:18, 4 April 2010 (UTC)[reply]

Could Poppy, the unreasonably cheerful character in the film "Happy-Go-Lucky" be described as suffering some kind of personality disorder? And is happiness or a alternatively a serious outlook on life gender specific, for example, does testosterone affect dopamine levels?[Trevor Loughlin]80.1.80.15 (talk) 10:45, 4 April 2010 (UTC)[reply]

It's fiction. Its unwise to attempt to deduce facts concerning real life from fiction. 78.149.241.120 (talk) 11:43, 4 April 2010 (UTC)[reply]

I've often thought that happiness is inversely proportional with intelligence, which might explain why small kids and the retarded often seem happier. They are thinking "I'm happy because I'm playing with a puppy !" while I'm thinking "I'm depressed because I'm playing with a puppy that will someday die, as will I, and as will the universe". StuRat (talk) 13:16, 4 April 2010 (UTC)[reply]

Sorry but that's just dumb. I am usually pretty happy and I am also intelligent. I work with small children and they are a mixed bunch. Some are always happy, some always morose, but most are like me, happy most of the time. Many people who are actually dying state that they are happy - they appreciate every day. Theresa Knott | token threats 14:50, 4 April 2010 (UTC)[reply]

I knew that as well, but I also knew that one of Nature's ways of making sure that my genes would reproduce better, was by making me feel happy about it :-) - DVdm (talk) 13:31, 4 April 2010 (UTC)[reply]

There is a correlation between size and intelligence? Since when? (Excluding children whose growth is stunted by malnutrition, disease, etc., which is a tiny minority of small children in the developed world.) --Tango (talk) 13:38, 4 April 2010 (UTC)[reply]

The chief criteria for a mental disorder is if it causes problems for the person, or the people around them. If people around her find her annoyingly cheerful though, that sounds more like an attitudinal issue on their end, rather than hers. See this link -- FDA approves depressant drug for the annoyingly cheerful. Warning, may contain humour. Vranak (talk)

The original questioner may want to read about definitions of mental illness. There is much debate in academic and professional mental health fields about this issue. Nimur (talk) 15:02, 4 April 2010 (UTC)[reply]

Though I didn't see it, review of the movie made me think the director's answer would be no.

On the other hand, there are some interesting psychological conditions which may be relevant. The most obvious is mania, a condition characterized by near euphoric feelings of optimism and ability. It sounds great but apparently it can also be tied to really hard lows, see bipolar depression, as well as some risky behaviors and a difficulty interacting with mere "mortals".

The movie's main character doesn't seem to have that, though so it might not matter.

Incidentally, if you ask an actual bipolar person, they'll admit that it having uncontrollable bouts of surging energy can itself be scary or even unwanted (perhaps only in retrospect).

More recent research into happiness shows that cognitive behaviors (ie positive thoughts)) can be improved, and brain scans of people who meditate show altered activity levels in parts of the brain linked to happiness.

You could also consider that our moods are partially determined by neurotransmitters like serotonin and dopamine, which could be genetically or periodically higher in some people than others.

As for the bigger picture there's an interesting though marginal theory that depressed people actually see the world more accurately and that happiness involves a kind of cognitive "shield" (see depressive realism).

Finally, its worth considering that poppy is the "normal" one, and everyone else is really bonkers. 68.171.235.107 (talk) 15:23, 4 April 2010 (UTC)[reply]

Your second question. Testosterone does not affect dopamine levels. However there is a relationship between Dopamine and serotonin. Kittybrewster ☎ 17:49, 4 April 2010 (UTC)[reply]

Also see height and intelligence, happiness and pursuit of happiness (pursuing happiness means you're unhappy). Usually, a relatively simple life leads to more happiness. Children tend to be happier due to generally fewer adverse life experiences and heightened curiosity, and as for why the "retarded" may seem to be happier–some may consider that word to be degrogatory, but it is likely due to the fact that many of them try to live to the fullest. Also, if intelligence is negatively correlated with happiness, does that mean Albert Einstein or Leonardo da Vinci would have been chronically depressed? It is highly unlikely that happiness would be gender-specific...what are the evolutionary advantages of that? ~AH1^(TCU) 22:24, 4 April 2010 (UTC)[reply]

No, that is not how correlation works. For example, consider a hypothetical world where anyone with an IQ_{(${\displaystyle \sigma =15}$)} between 100 and 130 is unhappy (happiness=0) anyone else is happy (happiness=100). In such a world intelligence would be negatively correlated with happiness, but Einstein and Leonardo would still be happy. (This, of course, has nothing to do with the original question – which is more about the meaning of 'disorder' than about happiness). –Henning Makholm (talk) 23:38, 4 April 2010 (UTC)[reply]

Happiness is a cigar called Hamlet! :)--79.76.175.65 (talk) 02:16, 5 April 2010 (UTC)[reply]

Don't know if this is the right place to ask but could anybody tell me what kidron is? I have a collection of books bound in kidron but I can't seem to find what type of material it is... Wikipedia doesn't have an article. I'd be grateful for any help! ; ) --91.49.119.20 (talk) 16:45, 4 April 2010 (UTC)[reply]

Are you sure that "kidron" is intended to refer to the material? The Kidron Valley is a location near Jeruselem and Kidron, Ohio is a town in the US - "bound in Kidron" could simply mean "produced in a bookbinding facility located in Kidron, Ohio/the Kidron Valley". If you are certain it refers to the cover material, it may be related to "kid", the term used for young goats, and for their leather. (Kid leather was regarded as a fine and elegant leather, see kid gloves.) -- 174.31.194.126 (talk) 16:57, 4 April 2010 (UTC)[reply]

Yes, thanks, I'm sure. A catalogue of the books can be seen [[20]]. The Oscar Wilde collection for example states that the edition is bound "in deep red Kidron" and the Macaulay Collection states that in addition to the lambskin and 23 kt gold bound collection the edition is also available in "golden embellished Kidron", indicating (IMO) that Kidron is a lesser material. Thanks for any further help. --91.49.119.20 (talk) 17:16, 4 April 2010 (UTC)[reply]

It appears, in this context, to be a kind of paper-plastic composite imitation leather. Probably a long-discontinued trade name. Google finds a few references implying that the same stuff (or something close enough to be mistaken for it) is also called "skivertex", and skivertex itself has ghits that look like they should be useful. –Henning Makholm (talk) 23:07, 4 April 2010 (UTC)[reply]

Whats known cure for head ace and flu KENNEDY NEWTON (talk • contribs) 00:05, 5 April 2010 (UTC)[reply]

[medical advice removed --Tango (talk) 00:40, 5 April 2010 (UTC)][reply]

We can't give medical advice, I'm afraid. There are lots of head ache and flu treatments available. I suggest you ask a pharmacist, they will almost certainly be able to help. --Tango (talk) 00:40, 5 April 2010 (UTC)[reply]

I presume that the "head ace" in question flies for a hostile air force? Well, you don't "cure" this situation, but if you find him to be a big problem for your own pilots, you might try to shoot him down. FWiW 24.23.197.43 (talk) 02:10, 5 April 2010 (UTC)[reply]

"A biological cell is immersed in a 70. mM solution of NaCl at 37°C. The cell's membrane is permeable only to Na+ ions. When the system reaches equilibrium, a potential difference of 55.4 mV is measured between the inside and the outside of the cell, where the inside has the higher (more positive) potential. Calculate [Na+] inside the cell, assuming the amount of Na+ ions transferred is negligible compared to the total amount of Na+ ions in the solution."

I'm aware that, at equilibrium, the chemical potential of Na+ inside the cell equals the chemical potential of Na+ outside the cell, according to m = m° + RT ln a + ZFo. But what are F and o? I plugged in the values but don't get the answer. —Preceding unsigned comment added by 70.68.120.162 (talk) 01:59, 5 April 2010 (UTC)[reply]

I think F_o refers in this context to the Faraday constant. I might be wrong, though, because I haven't done any electrochem calculations in a long time. FWiW 24.23.197.43 (talk) 02:20, 5 April 2010 (UTC)[reply]

One of my adult female cats has exhibited a new behavior pattern for the past several months that I've never seen before. She has always occasionally "played the piano", the rhythmic massaging of invisible mammaries done by adult cats that were weaned too early. Recently, however, she has combined that with the neck-bite-and-hold that male cats do when they mount the female to mate. So, when I'm laying on the sofa or in bed under a blanket, she will mount my leg and firmly bite the blanket, then begin simultaneously massaging my leg with her forepaws while purring most determinedly. Has anyone else ever seen a cat (especially female) exhibit this behavior? Does anyone have any idea what sort of "needs" are behind this? I can understand both components alone, but together seems a bit odd! 61.189.63.142 (talk) 03:04, 5 April 2010 (UTC)[reply]