Wikipedia:Reference desk/Archives/Science/2010 April 8

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April 8

Miners "surviving" by eating sawdust and bark

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

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

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

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

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

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

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

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

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

I gave my source. Here's two more discussing the potential to eat bark for nutrition [1][2]. Our own article on bark says: "The bark of some trees is edible...", and gives the example of a kind of bread made from tree bark. We eat lots of plants, like carrots and lettuce, that give us few calories per volume but aren't totally worthless. I suspect bark is in the same category. Not much useful nutrition but not zero either. If you believe there is nothing at all that is digestible in bark, then I suggest you give your source(s). Dragons flight (talk) 02:33, 8 April 2010 (UTC)

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

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

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

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

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

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

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

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

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

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

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

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

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

Are there diets that cause a person to not defecate?

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

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

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

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

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

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

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

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

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

Are you thinking of “Total" Parenteral Nutrition where someone has had their gut removed?[3]--Aspro (talk) 11:19, 8 April 2010 (UTC)

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

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

Help with a physics question

This is a link to a past pre-tertiary (grade 12) Physics exam: [4]
Read Question 9.
The answers to the exam are found here: [5]
Why do the positive and negative charges repel, as it would appear on the diagram on the answers document? I thought opposite charges attract.
--Alphador (talk) 06:12, 8 April 2010 (UTC)

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

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

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

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

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

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

Life project

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

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

Wikipedia's "team" at Folding@Home is currently ranked around 2,500 out of 175,000 teams: [6] 75.41.110.200 (talk) 15:17, 8 April 2010 (UTC)

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

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

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

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

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

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

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

SUV fuel tank

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Bees pollinated crops list: [7] Many of them are planted rows including vegetables and oilseeds, even apples and almonds (they're planted in rows, too!) Others aren't like alfalfa and clover. Occasionally oilseeds are broadcast planted. Rmhermen (talk) 18:22, 8 April 2010 (UTC)

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

Gastroenteritis

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

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

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

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

Armour vs railguns?

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

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

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

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

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

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

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

Need help identifying a Prunus species

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

Looks like Prunus americana to me. Does it have thorns? How do the flowers smell? P. americana flowers smell rather nasty. You may want to try asking at the Dave's Garden plant identification forum [8], they are very good there. Winston365 (talk) 01:58, 9 April 2010 (UTC)

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

shewees

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

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

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

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

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

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

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

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

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

is the following experiment valid?

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Apples numbing the lips.

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

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

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

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

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

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

Why do we need vitamin D?

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

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

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

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

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

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

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

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

Sexual attraction to skeletons

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

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

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

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

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

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

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

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

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

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

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