Wikipedia:Reference desk/Archives/Science/2006 August 31

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Beef jerky

Can beef jerky, and jerky in general, be reconstituted, perhaps using broth? I'm sure it would be terrible, but is it even possible? Bhumiya (said/done) 01:48, 31 August 2006 (UTC)

I believe an MRE kit contains dehydrated meat to be soaked in water, with the idea being that the finished product will resemble actual meat. StuRat 02:06, 31 August 2006 (UTC)

Since its only dried meat, I dont see why it couldnt be reconstituted by heating in a pan (or uwave) with water. Yummy--Light current 02:07, 31 August 2006 (UTC)

Most dehydrated things can't be rehydrated to get the original back. A raisin soaked in water, for example, doesn't give you a grape, it give you a soggy raisin. StuRat 02:14, 31 August 2006 (UTC)

Thats just sour grapes on your part! 8-)--Light current 02:20, 31 August 2006 (UTC)

And if soggy raisins get you mad, then they would be The Grapes of Wrath. :-) StuRat 02:29, 31 August 2006 (UTC)

Actually I thought raisins were made from special sorts of grapes but the current thinking is that currants raisins and sultanas are all in fact dried grapes. I see no reason to doubt that.--Light current 02:36, 31 August 2006 (UTC)

Maybe you can reconstitute it, but I do not think you will get a properly functioning cow back. --Lambiam^Talk 02:49, 31 August 2006 (UTC)

Has any one noticed that the indentation is now rather pretty? shame I have to spoil it!--Light current 02:56, 31 August 2006 (UTC)

Not really, we can still go back and forth to keep up the pretty little indentation thing. As for the question, you know when people do weird stuff on tv and tell you "Please, by all means, DO NOT try this at home"? Well I don't think that would apply here. I can't see much harm resulting if you boiled a piece of beef jerkey and waited to see what happened. Keep us updated, the scientific community is relying on you for this one. Loomis 08:42, 31 August 2006 (UTC)

Yes I suggest the questioner try it at home!--Light current 11:04, 31 August 2006 (UTC)

You can reconstitute food to some degree. The water has gone from the cells and they won't function like perfect sponges, but you can get some water in there. Reconstituted jerky is usually mentioned as good for stews. I doubt you get a good filet mignon out of dried meat. Google for rehydrate jerky or reconstitute jerky. Weregerbil 11:33, 31 August 2006 (UTC)

physics andtehnology

59.93.32.70 02:28, 31 August 2006 (UTC)anees application of physics in other science disciplines ,or how physics theories applied in different science subjecs

ronlem unnerstanig qestiom ,please suitly emphazi Lambiam^Talk 02:51, 31 August 2006 (UTC)

I can work out most of the words, but what the hell is 'ronlem' supposed to be? Hang on I just saw it!--Light current 03:15, 31 August 2006 (UTC)

Body hair

Why do men have more body hair than women. Do women not feel the cold as much?--Light current 03:10, 31 August 2006 (UTC)

To differentiate the genders. (We have to make the trannies work a little bit, don't we ?) :-) StuRat 03:32, 31 August 2006 (UTC)

A trannie is a transistor radio! It was when I was young.--Light current 03:33, 31 August 2006 (UTC)

Well, I wouldn't suggest you go around telling people you enjoy fiddling with the knobs on your favorite trannies. :-) StuRat 03:37, 31 August 2006 (UTC)

Can I have an anthropological answer please?--Light current 03:33, 31 August 2006 (UTC)

I gave you one. It's so men and women can tell each other apart, which is rather critical to reproduction and survival of the species. StuRat 03:46, 31 August 2006 (UTC)

For sexual dimorphism. I restate the first answer. — [Mac Davis] (talk) (Desk|Help me improve)

What about monkeys? They can tell the diff, and theyre all hairy!--Light current 03:47, 31 August 2006 (UTC)

I suspect that the general reduction of hair in modern humans came as a result of clothing, making the thermal properties of hair optional, and thus a candidate for sexual dimorphism. Body hair isn't the only way we have to differentiate the genders, but the more obvious the genders are, the better for the species. StuRat 03:52, 31 August 2006 (UTC)

Possible. I would like more views please. BTW does that mean you couldnt recognise a woman if she was hairy all over? 8-) --Light current 04:03, 31 August 2006 (UTC)

The actual functional purpose of human body hair is no longer directly relevent as - most of us at least - wear clothes. Dimorphic body hair is a secondary sexual characteristic, that is, it is a result of the genetic/biochemical differences between men and woman. Specifically, increased levels of androgens in males promote the transformation of vellus hair to terminal hair in certain parts of the body. The reason some parts grow more than others is probably due to the androgen sensitivity in the local follicles. Rockpocket 05:17, 31 August 2006 (UTC)

Hey Light current we recognized you didn't we! Lemon martini 08:00, 31 August 2006 (UTC)

As what, may I ask?--Light current 11:44, 31 August 2006 (UTC)

Conjecturing that we have less body hair because of clothing is sort of backwards to me. We've been less-haired for quite some time, and it's more likely that clothing came about as a result to warm ourselves in contexts where thick body hair could've worked. Considering that modern humans evolved in Africa and there are other less-haired mammals (like elephants) in Africa, I'd say it was something related to the African climate that led to diminished body hair.

As far as sexual dimorphism, males are generally flashier than females, as with the peacock's tail feathers, the Betta's bright colors, the lion's mane, the colorful parts of the mandrill and the silverback's, well, silver back. Body hair dimorphism, as well as facial hair was probably used in very early times in a way similar to the attraction schemes of these other animals.

It's also possible that, since then, cultures have found hairless women to be more attractive thereby affecting selection pressures as well as shaving and waxing practices that make us think that women are significantly less hairy. AEuSoes1 08:38, 31 August 2006 (UTC)

Yes I think this last reply sums it up nicely for me. THanks for all suggestions--Light current 10:55, 31 August 2006 (UTC)

Something else to consider. While the environment can probably to be ruled out as a cause (there are lots of primates in Africa and we were the only near-naked ones), the answer of sexual dimorphism seems incomplete or incorrect to me. For one thing, different nationalities have different levels of body hair - sexual dimorphism doesn't explain why Japanese men and women are both pretty hairless, compared to some Mediterranean men and women. For another, if dimorphism was that strong a selector, I think we'd see much hairier men and much, well, smoother women across the board. I can see the argument for facial hair being a sexual signal, but body hair itself doesn't seem all that clear to me. Matt Deres 02:03, 1 September 2006 (UTC)

Enthalpy and heat

What is the difference between heat (q) and enthalpy (H)? Also, I don't understand fully what entropy is. I know the definition as the amount of disorder, but how would you measure it? Also, how does disorder relate to q/T? Thank you very much, you are great people.--216.164.200.120 04:48, 31 August 2006 (UTC)

Is this homework? Look at the links.--Light current 04:51, 31 August 2006 (UTC)

No this is not homework (and by the way, Light current, I've noticed you saying many questions are homework when they aren't), and I looked at the links, but they are somewhat confusing to me. Please could somebody help. --216.164.200.120 04:58, 31 August 2006 (UTC)

I just reread my question and noticed that it does look a lot like homework, however I assure you it is not as I do not start school again 'till September.

OK it just looked like it. How do you know the others are not homework if you didnt write them? Apologies if Im wrong. What is wrong with the article explanations?--Light current 05:05, 31 August 2006 (UTC)

H = E + PV \,

where E represents the energy of the system. In the absence of an external field, the enthalpy may be defined, as it is generally known, by:

H = U + PV \,

where (all units given in SI)

   * H is the enthalpy
   * U is the internal energy, (joule)
   * P is the pressure of the system, (pascal)
   * V is the volume, (cubic metre)

which bit is not clear?--Light current 05:10, 31 August 2006 (UTC)

I was told that q = E + PV also, which doesn't make sense. What does q really equal?

Then I also still have the question about how you measure entropy and how q/T is related to disorder. --216.164.200.120 05:17, 31 August 2006 (UTC)

• Entropy in chemical systems is relatively easily determined. The change in Gibbs free energy for a reaction, dG, can be calculated readily from reaction data, since dG = -RT ln(K). and given dG=dH - (T x dS), you can simply subtract the enthalpic component dH, and find the entropic component dS at a known temperature T. its that easy ;-) Xcomradex 06:50, 31 August 2006 (UTC)

Enthalpy is basically heat, entropy is basically disorder. Things tend to:

give out heat (like a hot cup of coffee - it gives out heat);

become more disordered (like my bedroom - it keeps getting untidier and more disordered).

Physical processes tend to occur if either of the above two things can happen. If a process does both then it will happen. If it does neither then it won't, and if it does one but not the other then it's a balancing act and the temperature will decide whether it happens or not (that's why part of the equation is multiplied by T).

Systems like to get rid of energy - they can do this by giving out heat or becoming more mixed up. If it seems difficult to accept that systems can lose energy by becoming more disordered (mixed up), think about it in reverse - to make my bedroom more ordered (tidier) I have to put energy into it when I go round clearing it up.

Enthalpy is easily measured experimentally and entropy is calculated from various results and equations. Don't worry about Q/T, it just comes from rearranging the equations. Rentwa 08:16, 31 August 2006 (UTC)

Thanks for that, Rentwa! Rentwa 15:24, 1 September 2006 (UTC)

Yeah! That's just about the best darn dummies guide to Thermodynamics I ever read! Rentwa 15:25, 1 September 2006 (UTC)

Yes, thanks. You are great people - Rentwa 15:26, 1 September 2006 (UTC)

Don't mention it, it was my pleasure! Rentwa 15:28, 1 September 2006 (UTC)

I'm going to award you the barnstar for wasting your time helping ungrateful &&*^%'s! Rentwa 15:31, 1 September 2006 (UTC)

Please don't bother, it was nothing! Anyway, I'd rather have a picture of a dog in a trilby. Or a crocodile wearing a fez. Or a tram wheel and a dollop of porridge. Rentwa 15:34, 1 September 2006 (UTC)

Chin up, Rentwa. Sooner or later we all learn that providing answers to questions posed by anonymous ingrates is, like patience, its own reward. When you get to the point of making posts for the pure joy of doing so, without regard to whether or not anybody ever reads them, or if they do, what they might think of them, or of you, then you will have achieved true Wiki-transcendence. JackofOz 12:56, 3 September 2006 (UTC)

Steorn and Free Energy

What is the deal with these Irish people who claim to have proved false a large portion of scientific knowledge? It can't be true what they are saying; what are they trying to do?

Its too good to be true! (so it isnt)--Light current 04:59, 31 August 2006 (UTC)

I know, but I mean is this an ad campaign or what. --216.164.200.120 05:05, 31 August 2006 (UTC)

So far, they are maintaining it is genuine. However, as with all claimed scientific breakthroughs, it should probably be treated with skepticism until the process has successfully cleared the peer review process and the work been reproduced by other scientists. It does seem an extraordinary claim, but then again, the idea of a telephone or television was probably as fantastical at some point in time. Rockpocket 05:09, 31 August 2006 (UTC)

Probably problems with the measurements!--Light current 05:11, 31 August 2006 (UTC)

To be perfectly honest, how many legitimate scientists run ads in The Economist? Or set up flashy pages on flashy websites that seemingly were not used for any serious scientific stuffs before hand? Most legitimate scientists would at least hold back somewhat on something like this until they got some level of confirmation, rather than stirring up a media storm right away. There are also normal channels to go through instead of magazine ads. Anyways, best policy is probably to just take it with an enormous lump of salt until peer review is done with; if you took every revolutionary scientific claim completely seriously, you'd lose your mind in little time. -- Consumed Crustacean (talk) 05:21, 31 August 2006 (UTC)

The television and telephone were perfectly explainable using existing scientific theories. This "free energy" appears to directly contradict the laws of physics (which are not really "laws", but have been observed to hold true by physicsts, in this case for centuries). --Robert Merkel 05:27, 31 August 2006 (UTC)

You'll note i said "at some point in time". I'm sure, prior to the establishment of modern "scientific theories" the idea of seeing or hearing someone from another continent would be considered to contradict the "laws of physics" as we understood them at that time. Throughout history, when someone has challenged the paradigm, their works was initially mocked, see Reaction to Darwin's theory for example. I'm not suggesting the Steorn claim is genuine, but equally, it is scientifically flawed to argue it is fake based on a dogmatic adherence to so-called "laws". The fact is we do not yet know. Rockpocket 05:53, 31 August 2006 (UTC)

Yes, but at the time they were invented they were perfectly in harmony with the laws of physics as understood. This gadget isn't. And thousands of other proposed perpetual motion devices have failed before. It's not impossible this one is different, but it's pretty damned unlikely. Extraordinary claims require extraordinary evidence. --Robert Merkel 09:00, 31 August 2006 (UTC)

I'm sure there are plenty of theories or hypotheses (potential "laws") that could accomodate perpetual motion machines, its simply that they are not accepted by the mainstream as scientific. The reason they are not accepted by the mainstream is because it has hitherto proved impossible to prove (in this case empirically) and it does not sit comfortably with our current level of understanding. I completely agree that it is "damned unlikely" to be true, but if it was duplicated independently that would be extraordinary evidence. I'm willing to keep an open mind until then and not pre-judge. Remember we should be giving NPOV answers here whenever possible. Rockpocket 04:58, 1 September 2006 (UTC)

Lots of science is rubbish - thats why scientists are able to change their theories every few years! Evolution -> predicts new species evolve, but what do we observe? No new species evolve, but lots of existing ones go extinct - opposite of what theory predicts yet people still support it and in fact most Biologists actually think it's a Law of Nature!

Dark matter - cosmologists use theory to guess weight of Universe, then use observations to estimate weight - two figures disagree - sane person would assume theory wrong and evidence of eyes right, cosmologists invent special invisible matter to make theory right! [/rant] Rentwa 05:47, 31 August 2006 (UTC)

btw, we do see new species emerging, and evolution is not the oppposite of species going extinct. In fact, species that cannot evolve fast enough to new circumstances (ie, people with guns who kill more than the population can replace) would be expected to go extinct. 86.140.31.143 13:12, 31 August 2006 (UTC)

Where do you get the idea that no new species evolve? Darwin proved that species are evolving right now with the various new speciations being done on the Galapagos Islands. New species of moth were being created in Great Britain due to the sooty trees, but cleaner air has stopped the complete speciation of black and white moths. User:Zoe|(talk) 02:38, 1 September 2006 (UTC)

I'm trying to make a point about logic in scientific reasoning, or Empiricism vs. Theory, or the varying degrees of quality in scientific arguments. Darwin didn't prove anything. Just because something seems to be a plausible explanation doesn't mean it's true. 'If it looks like a duck...' may be acceptable reasoning in real life, but I think people interested in knowledge (ie scientists) should look into things more deeply. God and creationism looked like a pretty good explanation for the world pre Science, after all.

On more concrete matters - what new species have we observed on the Galapagos? I mean species that weren't there when people arrived and documented the existing fauna and have arisen since? None as far as I'm aware. Re the moths - the black form prospered during Industrial times and the lighter form is prospering now. So what? Not remotely like a new species evolving. Rentwa 13:10, 1 September 2006 (UTC)

It's obvious you're not interested in a real discussion. User:Zoe|(talk) 02:01, 2 September 2006 (UTC)

No. Humanity is responsible for wiping out lots of species, so it is a moral imperative for us to understand the mechanisms of biology so that we might correct ourselves. Evolutionary models are indispensible for investigations into the diversity of life. Dark matter is a hypothesis that makes many more important predictions than you seem to be aware of, and I can only refer to the article for those. It is necessary to hypothesize dark matter and reason about its properties so that we know how to look for it and decrease our ignorance. And no one is more careful to hedge statements about the unknown and verify theories than scientists. If you have been given a different impression by a hostile and uneducated press with no interest in the subtleties of knowledge, perhaps you should look to new sources of information. Melchoir 06:26, 31 August 2006 (UTC)

I'm ranting a little - the shortcomings of science is one of my pet bugbears (and I'm right too - see my original point - if the theories were correct it wouldn't be possible to revise them), but re your point about knowledge - my impressions were gained at an ancient British university, and it's academics, I'm afraid, who are the blindest of all to its subtleties.

This chap, btw, is quite good on free energy. Rentwa 06:46, 31 August 2006 (UTC)

A theory does not have to be absolutely correct to be useful to scientists and society alike. This is a strength of science, not a shortcoming, because we cannot and should not expect to be certain about anything. As for academics, my personal experience of researchers is that the successful ones are quite aware of the historical wrong turns their fields have taken. Melchoir 06:58, 31 August 2006 (UTC)

There's a spectrum of theory quality. Gibbs Free Energy above (misunderstanding of name possibly accounting for current interest) is brilliant, as is most of Thermodynamics. Unfortunately (as I'm sure you would agree) that's one end of the spectrum.

And I disagree completely with your observations on successful researchers (perhaps I'm just bitter!) Orthodoxy is the thing that counts. Rentwa 07:13, 31 August 2006 (UTC)

Fair enough. I won't claim to be a sociologist! Melchoir 08:32, 31 August 2006 (UTC)

No, honestly, I was ranting! (Don't_disrupt_Wikipedia_because _you're_too_mean_to_pay_for_therapy) ;-) Rentwa 08:39, 31 August 2006 (UTC)

Atoms

Can scientists directly see atoms? What kind of microscopes are used? If it's still impossible, what capabilities would a microscope require in order to be able see the atom?

I was just wondering. I assume electron microscopes are used to get a sense of the election cloud surrounding an atom's nucleus but viewing the nucleus itself isn't yet possible. I'm not sure though. - Pyro19 08:53, 31 August 2006 (UTC)

Microscope is a good (and obvious) starting point. That leads you to Scanning tunneling microscope. Another one would be atom, where you can search for 'microscope'. DirkvdM 09:17, 31 August 2006 (UTC)

• A common way to get a look at atoms (be it indirectly) is X-ray crystallography. And another method (actually the first) to actually visualise atoms is the field ion microscope. an actual picture [1]. Xcomradex 10:25, 31 August 2006 (UTC)

Wow, never knew atoms were so slimy-looking. :) DirkvdM 09:14, 1 September 2006 (UTC)

With all of these visualizations there are a lot of assumptions which have to be made about the data—you are never really looking at the "atom itself" in the way that one normally thinks of "looking", so it is all "indirectly" in a sense. But once you start really interrogating what "looking" means at the atomic and subatomic level, it gets pretty hard to say that you see anything "directly". In any case, the most famous picture of individual atoms is the IBM logo made out of 35 Xenon atoms. As you can see, they look more like probability functions than what one might expect an actual atom to "look like" from a human point of view. --Fastfission 14:54, 31 August 2006 (UTC)

Claiming that's the IBM logo is a bit much. Let's be reasonable here and just call it what it is, the letters IBM.  freshofftheufoΓΛĿЌ  13:02, 1 September 2006 (UTC)

The definition of "looking" is something to note here. The most common way to "look" at something is to throw things at it, and see what they do. That is why we make particle accelerators (atom smashers), so we can "look" at things that we can't "see." In normal life, we do this. One could say when you switch on the light bulb, photons fly out and bounce off of objects, and the photons eventually reach your eye. Based on the qualities of the photons that reach your eye, you "see" objects. — [Mac Davis] (talk) (Desk|Help me improve)

Wait, there's something I'm still not getting. Is it impossible to see an atom due to quantam effects or something? That picture that Xcomradex linked to, are those little round balls actual individual atoms or are they an approximation? - Pyro19 15:24, 1 September 2006 (UTC)

You can only clearly "see" something using a wavelength that's quite a bit smaller than the size of the object you're trying to see. Oridnary light in the visible spectrum clearly won't do for visualizing individual atoms; the atoms are smaller than the wavelength of the visible light. So you'll never be able to use your eyes directly through some kind of ultramicroscope to see an atom. That's where the shorter wavelengths used in X-ray crystallography come into play. But even those are pretty big and the atoms aren't imaged individually. Instead, they act en mass like a diffraction grating.

Instead, we use particles that have the equivalent of a very short wavelength (those "ions" that were mentioned above in the field ion microscope).

Alternatively, we can use actual touch (or the quantum equivalent of "close enough"). That's how the various scanning tunneling microscopes, atomic force microscopes, and the like work.

Atlant 00:33, 6 September 2006 (UTC)

Distance traveled by a soccer ball when kicked in different angles.

When a soccer ball is kicked at an angle exactly paralled to the ground, that is , making an angle of 0 degree with the ground, will it travel more horizontal distance or when it is kicked making a certain angle with the ground  ? Force applied in both the cases is taken as same.

I'll leave to that someone more capable, but essentially zero degrees would either mean slipping or rolling, right? Well, it depends on the material of the ground : grass, ice,... Evilbu 11:32, 31 August 2006 (UTC)

I think you have to clarify your question... do you mean kicking it down or up? If you kicked it up it would most certainly travel further than kicking it along the ground for angles less than 45 to the ground. Kicking it downwards should cause it to bounce and lose a lot of energy on impact with the ground, but exactly how much energy it loses is hard to say... you might have to stage a real-life trial to figure that out.  freshofftheufoΓΛĿЌ  12:03, 31 August 2006 (UTC)

I think the question is, essentially, what is the optimum angle to achieve the greatest distance. According to our trajectory article, this is 45 degress.--Shantavira 13:57, 31 August 2006 (UTC)

While 45 degrees is absolutely correct for idealized cannonballs, soccer balls will behave differently. I'd put "optimal" at a lower angle, say 20 to 30 degrees, to keep most of the air time while reducing the energy lost at landing and improving the horizontal speed component for the post-landing roll. — Lomn | Talk 15:12, 31 August 2006 (UTC)

It is 45 degrees if the ball does not spin. Forward spin or back spin will alter that a bit. --Kainaw ^(talk) 15:14, 31 August 2006 (UTC)

When a goalie kicks it as far as he can, it is at a much greater angle than 30 degrees. --liquidGhoul 15:15, 31 August 2006 (UTC)

It's worth noting that when the goalie kicks the ball, the ball never goes as far as it could. There are always players in the way; those players aren't going to let a ball bounce and roll out to its maximum distance. The angle at which the ball leaves the goalie's foot is going to be something of a compromise.... TenOfAllTrades(talk) 15:21, 31 August 2006 (UTC)

45 degrees is correct for ideal cannonballs on the moon—that angle doesn't take into acount the effects of air resistance. When we look at bouncing and rolling, then you have to take into account the properties of the ball and the grass; it's a mess. TenOfAllTrades(talk) 15:21, 31 August 2006 (UTC)

...only if the moon has a radius much larger than the cannon's range, and its muzzle velocity is small compared to the moon's escape velocity. Skimming those articles for numbers, the assumption doesn't look so good. So really, 45 degrees is correct in thought experiments and textbooks. Melchoir 17:18, 31 August 2006 (UTC)

Okay, okay. 45 degrees is the optimum in an airless environment where the curvature of the surface is negligible compared to the length of the ball's trajectory and the gravitational acceleration is approximately uniform throughout the ball's flight. Once you start removing those assumptions the calculation quickly starts getting difficult. To a first approximation, since it has air resistance, the best angle to kick a soccer ball for maximum range would be a bit below 45 degrees, although I can't calculate it exactly since I don't know the drag coefficient of soccer balls, and am not taking into accounts the effects of spinning the ball... — QuantumEleven 07:34, 1 September 2006 (UTC)

specific question for medicine/hematology

Dear Sirs,

I have read a certain writing on a disease/disorder called hyperkaliemia and I understand that it is composed of hyper-, kalium (potassium)and (a)emia (referring to blood). Where can I find more specific info on the disease because I could not find anything in the Wikipedia. Greatful in advance for any help from your specialists.

Very truly yours, Mr. Antti Stenberg Helsinki, Finland82.181.113.180 12:06, 31 August 2006 (UTC)

You were close. It's spelled Hyperkalemia. -- Plutortalkcontribs 12:26, 31 August 2006 (UTC)

Redirected. You can help!  freshofftheufoΓΛĿЌ  12:39, 31 August 2006 (UTC)

Surviving by drinking seawater

I have read accounts of shipwrecked people who claimed to have survived by drinking seawater, while other accounts--including Wikipedia--state that this is likely to lead to kidney failure. What is the correct answer? --Mugogo

• Kidney failure, salt water just doesn't quench thirst, it makes it worse. Even if you could drink large amounts of it, it wouldn't do you any good unless you made a point of distilling it first--VectorPotential^{71.247.243.173} 16:10, 31 August 2006 (UTC)

Also, try not to eat things that will not benefit you after digestion. If you eat your leather boot, your stomach may be filled, however you are killing yourself by spending more energy trying to digest a boot that has no nutritional value to you whatsoever. Regarding the water, you can distill seawater or urine, then drink the product. Solar stills are the most common and efficient way of doing this. — [Mac Davis] (talk) (Desk|Help me improve)

Do you actually need to distill the urine? I heard it can be drunk raw/neat/warm. Our page:

Urine on the other hand contains salt, which makes it unsuitable to drink. You can, however, make drinkable water from urine by distilling it.

So if there was little or no salt you could drink it. Otherwise you could try to remove the salt somehow.

--Light current 16:45, 31 August 2006 (UTC)

The other question is the stuff that causes the yellow/brown pigmentation of urine. Also theres urea. Im not sure what effect that has if it builds up in the body.--Light current 17:17, 31 August 2006 (UTC)

Too much urea will become toxic. People who wet the bed also know that it causes a nasty skin rash. The brown pigmentation is due to red blood cells and their broken down constituents that have made it through the renal filters. You shouldn't drink distilled urine unless you could guarantee you've distilled pure water out of it, which is unlikely if you're stranded at sea with a makeshift distiller. Nimur 17:38, 31 August 2006 (UTC)

You could always try eating the cabin boy.--Shantavira 17:30, 31 August 2006 (UTC)

Having quickly read that art, it seems to me they were unjustified in eating him after only 8 days or so. Im sure humans can survive a coulpe of weeks with no food.!--Light current 17:45, 31 August 2006 (UTC)

Actually, the yellow color comes from urochrome and bilirubin. While excess levels of bilirubin in the blood can be toxic, I am unsure whether ingesting them would cause them to accumulate in the body or whether they would be broken down by the digestive process. Plus, sunlight helps the body breakdown bilirubin, thus if you are stranded on a raft out at sea and decide to drink your urine, there would be plenty of sun to help you brak down all that bilirubin! Nrets 17:36, 31 August 2006 (UTC)

So the moral of the story is: make sure yuo take a small still with you into the life boat and drink as much as you can before abandoning ship! Also looks like that art on urochrome needs expanding considerably.--Light current 17:49, 31 August 2006 (UTC)

However, drinking pure distilled water is not good for you either, as it contains no electrolytes and will wash everything out of your body. You may be best off with neat urine (for the electrolyes) diluted with the distilled stuff (might taste better too!)--Light current 18:00, 31 August 2006 (UTC)

Why would that be? I never considered it, but always thought your body's maintenance, requiring water— distilled water would suffice somewhat. Ok, bad sentence construction, but you get what I am trying to say. — [Mac Davis] (talk) (Desk|Help me improve)

Distilled (pure or deionised water) I believe is very attractive to ions of potassium , sodium etc in the body and will leach them out leaving you short!--Light current 19:34, 31 August 2006 (UTC)

Add a teaspoon of sea water. --liquidGhoul 23:54, 31 August 2006 (UTC)

After the revolutionary army (as far as one can call it that) landed in Cuba they got into big trouble and after a while found themselves with little drinking water in a saltwater environment. So Che said he had read that if you mixed the drinking water with salt water you could double your available water. So they tried that. This made Che very impopular over the next few days. :) DirkvdM 09:25, 1 September 2006 (UTC)

A very old military practice is to put salt in drinking water - not to increase the water, but to increase the body's ability to hold water. A little salt will increase absorbtion. Too much salt, and you lose water. You judge it by how much you urinate. Keep adding salt until you urinate much less frequently. Then, if you continue adding salt, you will urinate a LOT more (and it is a bit painful). I was lucky. My body likes two standard issue packets of salt per standard issue canteen. No worrying about half-packets or anything like that. --Kainaw ^(talk) 19:11, 1 September 2006 (UTC)

I understand that one shouldn't have more than 6 grams of salt per day, as a nutritional rule of thumb. While this information generally relates to adding salt to meals, I believe it serves as a rough average of how much daily salt intake is considered "healthy" (by British standards.) CptJoker 02:08, 3 September 2006 (UTC)

But the gram is an SI unit, so British standard don't apply here. DirkvdM 05:27, 3 September 2006 (UTC)

Physics

Why are Germanium and Silicon which have 4 valence electrons classified as semiconductors, whereas Carbon which also has 4 valence electrons is vlassified as an insulator?…—Preceding unsigned comment added by Salvadesswaran ps (talk • contribs)

Diamond#Electrical properties might help. It's not much, though. Melchoir 16:43, 31 August 2006 (UTC)

Carbon is not an insulator. I think it may be classed as a semiconductor.--Light current 16:52, 31 August 2006 (UTC)

Graphite is a conductor. Nimur 17:10, 31 August 2006 (UTC)

For the full story, there are many allotropes of carbon. I think diamond is the most relevant to the analogy with silicon and germanium. Melchoir 17:12, 31 August 2006 (UTC)

Agreed - depends on the form. Its either a semi conductor (diamond) or a conductor. I dont know of any insulating forms.--Light current 17:32, 31 August 2006 (UTC)

In other news, check out the French link under "in other languages" for Aggregated diamond nanorods. Honestly, nanobaguettes? How do they say that with a straight face? Melchoir 17:38, 31 August 2006 (UTC)

Diamond is a semiconductor. I went to an interesting lecture last year on the current research into diamond semiconductor research and promptly forgot most of it, but I do remember that diamond semiconductors can operate at my higher temperatures than silicone and are also completely non toxic in the body (andriods anyone)? Theresa Knott | Taste the Korn 17:39, 31 August 2006 (UTC)

and don't forget the bigger picture, the periodic table, and metalloids. Xcomradex 21:38, 31 August 2006 (UTC)

Whether a solid material is a conductor, semiconductor or insulator depends on a parameter called the band gap, the energy difference between the "valence band" (where there are electrons) and the "conduction band" (where they would have to go in order to help conduct electricity). In conductors, there is no band gap, so the electrons are free to conduct. In insulators, the band gap is "large", and there is no conduction. In semiconductors, the band gap is "small", so that a few electrons can be kicked up into the conduction band by thermal excitation (their heat energy), especially if they are helped along by the trick called doping. Clearly the boundary between "small" and "large" band gaps is fuzzy. Diamond has a larger band gap than silicon and germanium, and under normal conditions behaves mosty like an insulator (being essentially insulating to electricity, being transparent to light, etc.). However, its band gap is much smaller than those of typical insulators, and diamond does behave as a semiconductor at higher temperatures, or if doped. There is a fair bit of research on diamond semiconductor devices, so stay tuned for cool products in the future. mglg_(talk) 22:39, 31 August 2006 (UTC)

Science of gayness

What disturbances in childhood cause gayness? Also, if there is a genetic component(as found in fruit flies), to what extent does it affect humans? --216.164.200.224 16:58, 31 August 2006 (UTC)

Check the homosexuality or human sexuality articles for a baseline. This is a topic which doesn't have a precise answer; a lot of research is still ongoing. Nimur 17:09, 31 August 2006 (UTC)

Doesn't the relative commonness of homosexuality rule out genetics? Two people of the same sex can not produce a baby of their own passing on their genes if they are fittest? I guess we would have to go to Papua New Guinea to see how gay people are there and compare it to, say, the United States. — [Mac Davis] (talk) (Desk|Help me improve)

Mac you have a lot to learn about genetics. By that argument, brown eyes and black hair and heterosexuality have no genetic basis-- in fact, by that argument, being male or female has no genetic basis. alteripse 20:05, 31 August 2006 (UTC)

A putative gene for gayness might predispose for strong sexual attraction towards men and reside on an autosomal chromosome, and thus create this attraction irrespective of whether the carrier was male or female. The benefit of increased reproduction of female carriers might outweigh the reduced reproduction of male carriers of the gene. --N·Blue ^talk 19:51, 31 August 2006 (UTC)

I've heard of several sets of identical twins where one was gay and one was not, so it's unlikely to be purely genetic. At the same time, I would think it extremely unlikely that something like this wouldn't have a genetic component. At a personal guess, there is probably an inherited tendency which, for whatever reason, is sometimes expressed and sometimes not. Skittle 20:14, 31 August 2006 (UTC)

Fruit flies have nothing to do with human genetics—they are just model organisms with which we understand different aspects of how genetics works; they do not tell us anything much about the actual expression of human genetics (anymore than human genetics would tell us about fruit flies). --Fastfission 20:21, 31 August 2006 (UTC)

What do homosexuals call themselves? Homosexuals or gays? I dont theink the original title was offensive to anyone. Please change it back! 8-(--Light current 20:27, 31 August 2006 (UTC)

What disturbances in childhood cause gayness? I admit I cringed when I read "disturbances", as it seems to imply that it takes something wrong/bad/weird (i.e., not an amoral event) to turn a child gay or something. But, despite the poor word-choice, there's a good question here.

First off, it's important to not think of sexuality in binary terms; the Kinsey scale or Klein Sexual Orientation Grid are sort of a crude measurements of where one might fall in this spectrum. Biology and sexual orientation & Choice and sexual orientation may have more useful, relevant information, too. Whether one is "gay" is a quasi-subjective establishment--obviously those that have only ever been exclusively attracted to and sexually active with one sex are pretty clearly "straight" or "gay", but there's a very large portion of society that doesn't fit perfectly into those categories.

For the genetics: there will (likely) never be a single definitive, all-encompassing "gay gene" discovered because, frankly, it would most likely be readily selected against. But, there are genetic regions that associate with homosexual traits.[2] These may, among other things, encode differential development of the sexual dimorphic nucleus, efficacy of aromatase, or perhaps some temporal difference in hormonal signaling during fetal development, for example. It's still largely unexplored.

Finally, the preponderance of scientific evidence is that human sexuality is determined, in large part, by genetic and epigenetic control of developmental processes (and maybe some important effects in olfaction). But, probably not 100%...the way I'd think of it: imagine that spectrum as simple line or axis, continuous rather than segmented into integers as in the scales above; one's genetic & epigenetic characters probably define a narrowed region of said spectrum as the destinations for one's sexual identity. Environmental factors, in and out of one's control (such as maternal hormonal effects in utero or sociological forces), narrow it to a single (but not necessarily immobile) point. -- Scientizzle 23:59, 31 August 2006 (UTC)

Very nice answer, Scientizzle *round of applause* Rockpocket 04:46, 1 September 2006 (UTC)

Thanks. -- Scientizzle 04:57, 1 September 2006 (UTC)

On NorwegianBlue's comment: yes, that would make sense. See also [3] which has a similar but more complicated idea. – b_jonas 13:02, 2 September 2006 (UTC)

biogas

how do biogas reactors produce pressurized methane without pumpos?

Anaerobic digestion has your answer. The way I see it, they just grind up the pumpos and throw it in! --Zeizmic 20:11, 31 August 2006 (UTC)

Carbon

What is it about carbon that allows it to have some many allotropes and forms with such differing properties. Is any other element so versatile. Im not a chemist, so can you keep it simple? Thanks--Light current 20:16, 31 August 2006 (UTC)

• Allotropy also makes the point of elements having multiple oxidation states (many workable arrangements of electrons) and variable co-ordination numbers (many workable arrangements of neighbouring atoms) (both apply to carbon) having more allotropes. and there are other elements with large amounts of allotropes too,eg. black, white and red phosphorus for example; oxygen, ozone and tetraoxygen, and sulfur has even more than carbon. Xcomradex 21:47, 31 August 2006 (UTC)

So sulfur could produce some interesting forms? Is that right? Are all these elements in a particular region of the periodic table as well?--Light current 21:52, 31 August 2006 (UTC)

Looks like theyre all in the non-metals part. How gratifying! So Selenium may have the same allotropic versatility as well?--Light current 21:57, 31 August 2006 (UTC)

• you got it. there's red powder selenium, red crystalline selenium, as well as the useful gray semi-metallic selenium. Note that one of the allotropes of sulfur is S₈; likewise selenium has an allotrope Se₈. don't you love the periodic table B-) Xcomradex 22:08, 31 August 2006 (UTC)

Seems good to me!--Light current 22:10, 31 August 2006 (UTC)

• If you're in search of more allotropic fun, or other periodic table stuff, [4] is good site. Xcomradex 22:22, 31 August 2006 (UTC)

Isn't this versatility of carbon a reason it is a basis of life on Earth? And if so, could life then be based on something like Selenium or Sulphur? DirkvdM 09:31, 1 September 2006 (UTC)

yeap. alternative biochemistry. Xcomradex 11:05, 1 September 2006 (UTC)

Silicon is the only other equivalent to carbon, the others differ in ways, but can be made to work. Philc _T^E_C^I 15:23, 1 September 2006 (UTC)

Silicon is a rather poor substitute for carbon, mainly due to its lower electronegativity and the larger size of its p-orbitals. Pure silicon analogues of organic compounds, such as silanes, simply don't hold together as well, especially where double bonds are involved. Silicon can replace a carbon atom in a mostly carbon molecular framework, but such organosilicon compounds are often reactive and break easily apart at the silicon atom. See also Silicon#Silicon-based life. —Ilmari Karonen (talk) 19:45, 2 September 2006 (UTC)

Orangutans in TV and Movies

I have seen trained Orangutans in American movies and Television,.How is it legal for for Animal trainers (and other private individuals) to own and exhibit Orangutans when they are an endangered species, And where are these people buying them from? I know they are not imported from the wild anymore.—Preceding unsigned comment added by 74.234.31.7 (talk • contribs)

• Unless they're eating and/or sterilizing the Orangutans, I don't suppose that simply having them on film would do much to jeopardize their conservation status--71.247.243.173 22:48, 31 August 2006 (UTC)

there is a danger that such orangutans may become acustomed to the movie star lifestyle, and be unable to find bagels in the wild. Xcomradex 22:55, 31 August 2006 (UTC)

How much do they get paid for appearing in films?--Light current 23:25, 31 August 2006 (UTC)

I've heard they work for peanuts, but that may be elephants--71.247.243.173 23:30, 31 August 2006 (UTC)

The problem with using them, is that people are making money from an endangered species. If it is profitable to exploit them, then it is more likely people will take them from the wild. Also, most zoos and such have breeding colonies, so they can release them into the wild. If the orangutan is being used for television instead of being in a breeding program, that will lower the diversity of those which are released, and lower their chance of survival as a species. --liquidGhoul 23:44, 31 August 2006 (UTC)

Seeing as how our article on Orangutan#In_popular_cultureOrangutans, only has 3 pop culture references, one of which is a cartoon, I don't think they actually are used in film/TV all that often, if at all--71.247.243.173 00:18, 1 September 2006 (UTC)

The last one I remember was Clyde appearing with Clint Eastwood.--Light current 00:20, 1 September 2006 (UTC)

Dunstan Checks in , George of the Jungle, Baby's Day Out, Fear and Loathing in Las Vegas,Babe 2 Many comercials for among other things Credit Cards, Tang, Domino's pizza

• The last time I saw Orangutangs (sp?) was in Serious Jungle and that program was about conservation and they were still in the wild. - Mgm|^(talk) 08:04, 1 September 2006 (UTC)

Yeah, last time I checked, it was a gorilla in George of the Jungle (film), and wasn't it a robot?  freshofftheufoΓΛĿЌ  12:47, 1 September 2006 (UTC)

I was not refering to George's talking side kick "Ape" .There were orangutans as background characters in the moive along with Chimps , Capuchin Monkeys and other primates.

Yes, I do believe there were. In cages? At a zoo? It's been a long time since I saw that movie.  freshofftheufoΓΛĿЌ  07:02, 2 September 2006 (UTC)

automotive

I am trying to figure out more information on car's body stiffness. Can you help? —Preceding unsigned comment added by 65.169.154.2 (talk • contribs)

Cars with frames tend to be stiffer than unibody cars. Modern cars tend to be intentionally designed not to be stiff, so they will collapse in a severe impact, thus reducing the deceleration effect on the passengers. See crumple zones. What other info do you want ? StuRat 00:11, 1 September 2006 (UTC)

The term can be used in a variety of ways. StuRat has explained how compressional stiffness is important to a car: safety is increased in cars which "crumple" within certain bounds. Car manufacturers often will subjectively rank torsional stiffness between models. A higher torsional stiffness will help keep all four wheels on the road in tight turning situations. A lower torsional stiffness is why convertibles often handle "worse" than similarly specified coupes. Also important is resistance to bending, or sheer forces. This type of stiffness is more complicated. Anti-roll bars, for instance, will be more resistant to sheer stresses and help both tires on opposite sides of the car stay in synch. However if sheer stress is increased too much, any stresses or damage that would have previously only affected only one side of the car will now affect both sides. Stiffness is also a term used to describe various shock-absorbing apparati between the wheels and the chassis, but since you asked specifically about the body stiffness, I'll spare you.Tuckerekcut 00:34, 1 September 2006 (UTC)