Wikipedia:Reference desk/Archives/Science/2010 August 11

= August 11 =

Dunning–Kruger effect
Our article on this effect includes a short bit of discussion about individuals who previously recognised this effect. Would it be reasonable to say that Socrates observed this effect, since according to legend he was told that he was the wisest of all men because he knew that he wasn't wise? Nyttend (talk) 02:13, 11 August 2010 (UTC)


 * I don't think we could say that with confidence about someone who lived 2500 years ago. SteveBaker (talk) 02:44, 11 August 2010 (UTC)
 * Why not? I don't see the difference, especially since the article includes those who remarked about the phenomenon before Dunning or Kruger were born.  Nyttend (talk) 04:57, 11 August 2010 (UTC)
 * "according to legend" - nuff said. Note that if you are trying to add it to the article, you should be discussing it in the article talk page not here. Presuming other sources have made the connection you may be able mention that, it doesn't mean we can say with confidence Socrates observed the effect which is a quite different thing.
 * I would also note your statement doesn't really support the claim at all since you say "he was told that he was the wisest of all men because he knew that he wasn't wise" which would suggest someone else recognised this effect not Socrates. Whether Socrates even recognised the effect once told about it or whether he thought the person who said he was the wisest of all men because he knew that he wasn't wise was an idiot is not even clear from what you've described.
 * Nil Einne (talk) 06:32, 11 August 2010 (UTC)

Banding during sunset
Take a look at this picture I took of a sunset. Notice the banding? Does anyone have any idea what might be causing that banding? It's not just a photographic artifact (though it may be not faithfully recreated by the camera); I took the picture because I noticed the banding with my eyes. At the bottom is obviously a cloud in front of the sun, but on the other half of the sun, there's nothing obvious to cause the interesting coloring. It was taken August 5th in southern Minnesota, if that makes a difference. Buddy431 (talk) 02:38, 11 August 2010 (UTC)


 * Mach bands - maybe. SteveBaker (talk) 02:42, 11 August 2010 (UTC)


 * My guess is that the photograph was taken on a day when there were numerous layers of diffuse cloud and strata of humidity, perhaps enhanced by strata of pollutants. The photograph was taken when the sun was in such a position that it was observed through a number of these strata.  As a result, the color of the sun was affected by the various strata in the atmosphere and so the sun shows distinct bands.  It would be useful to take a few more photographs with the sun at the same elevation, both in the morning and in the evening.  I wouldn't be surprised if the bands are only a rare observation.  Dolphin  ( t ) 03:15, 11 August 2010 (UTC)
 * I don't think this is rare. I'm seeing lots of air pollution in that image, possibly smog or smoke from a wildfire of some kind.  The temperature also appears to be above 30 C based on news reports in that region.  Although there was a small fire in that area in the morning the photograph was taken, smog is a known problem during the summer, with local reports blaming gas-powered lawn mowers, in addition to wood fires, ATV's and cars. Viriditas (talk) 04:00, 11 August 2010 (UTC)

Now we know where the cutout went. Cuddlyable3 (talk) 09:46, 11 August 2010 (UTC)


 * It's probably due to different layers of atmospheric thickness and relative humidity, as the lower layers may have more particulate matter that turns the Sun red. It might be related to the green flash. ~ A H  1 (TCU) 15:49, 11 August 2010 (UTC)

More finds
These small salamanders are found under slabs of rock within several feet of a stream. What are they? They are very common. Most of them have the stripes down the back. --Chemicalinterest (talk) 13:03, 11 August 2010 (UTC)
 * According to this document from the New Jersey (I assume the NJ on your image is that) Department of Environmental Protection, etc. etc., there are 14 or 15 different species of salamander and several of them have stripes. There is a gallery of photos at the bottom of the document. Richard Avery (talk) 15:40, 11 August 2010 (UTC)
 * Thanks for the document. The specs seem to indicate this species. --Chemicalinterest (talk) 17:02, 11 August 2010 (UTC)

Reverberation
Lets say I'm voice chatting on my computer using skype or something. And I while we are chatting, I can hear my voice on the other person's computer. Would this "echo" be described as reverb? 148.168.127.10 (talk) 13:24, 11 August 2010 (UTC)
 * I don't think so. It's audio feedback, isn't it? The reverberation article seems to indicate it applies to echoes only. That is, I think feedback would be disqualified because it uses new sources of sound (the speakers) rather than a reflection of the original sound. Vimescarrot (talk) 13:59, 11 August 2010 (UTC)
 * I concur that "reverb" isn't really applicable, and that "audio feedback" is probably accurate. If you want a reverby sort of word, though, it's a retrans. 199.209.144.218 (talk) 14:14, 11 August 2010 (UTC)
 * There are two forms of echo in Telephony: Near-end echo has no delay and is desirable in a small amount as a Sidetone so the telephone does not seem "dead" to the user. Far-end echo is echo of one's own voice delayed; it is undesireable and may be caused electrically by a poorly balanced Telephone hybrid or by acoustic link between the far telephone speaker and microphone. The OP is hearing far-end echo. Cuddlyable3 (talk) 16:31, 11 August 2010 (UTC)


 * In my experience "reverb" is used to describe a reverb-y sound regardless of source. So, if the end result is a reverb type sound, then yes, I suspect people would call it reverb.  Friday (talk) 16:38, 11 August 2010 (UTC)

mockingbirds
why do mockingbirds open their wings repeatedly while searching for bugs in the grass?--Horseluv10 13:27, 11 August 2010 (UTC) —Preceding unsigned comment added by Horseluv10 (talk • contribs)
 * I'm not sure that anyone knows the answer to that yet and I don't think it's really covered in Wikipedia which is a pity. There seem to be all sorts of theories e.g. it enhances their foraging by surprising the insects..somehow, anti-predator defense, territorial defense etc or maybe all of the above and more. Other mimids do it too.  Sean.hoyland  - talk 14:01, 11 August 2010 (UTC)
 * It may be because they are shading the ground for better visibility. 92.28.244.237 (talk) 09:51, 12 August 2010 (UTC)
 * Actually the opposite of shading has also been proposed as another explanation i.e. the exposure of bright white patchs during wing flashing illuminates prey. That theory is slightly ruined by several mockingbird species without white patchs flashing their wings while foraging...  Sean.hoyland  - talk 10:06, 12 August 2010 (UTC)

Phage therapy
After reading phage therapy, including the obstacles section, I don't see a reason for why phage therapy is not licensed for medicinal use in Western countries like the U.S. and the U.K., especially given the ever-rising resistance against traditional antibiotics. Safety is a slight concern, though it's generally considered safe under supervision to look out for toxic shock. I'm guessing it has something to do with the practicality of having to develop very specific strains of phages. Is this uneconomical at present? Regards, --— Cyclonenim | Chat 15:03, 11 August 2010 (UTC)
 * Anyone? Regards, --— Cyclonenim | Chat 10:52, 12 August 2010 (UTC)
 * Did you read the article you linked to? Phage therapy is not as well structured as it could be, but there are several points in it that explain why the therapy is not in wide use: The patient mounts an immune response against the phage, so you probably can use every phage only once. You have to know very specifically what kind of bacteria (or even mix of bacteria) has infected the patient, which is impractical as of now (that could change if sequencing costs keep dropping). Another point, which is not raised in the article I think, is that antibiotics are very cheap, and phages are not, at the moment. With multiresistance on the rise, the picture could change, but at the moment, phage therapy does not seem to have an advantage over antibiotics. --TheMaster17 (talk) 11:52, 12 August 2010 (UTC)
 * Thanks, I did read it but I only skimmed through it really. Even if you can only use each phage once in each patient, that doesn't seem like a massive reason not to use phage therapy. For example, certain rarer infections that people are only likely to get once could be treated by phage if not by antibiotics. Fair point regarding costs, I suspected it'd have something to do with that too. Regards, --— Cyclonenim | Chat 12:12, 12 August 2010 (UTC)
 * Since phage therapy is used in Russia successfully, there is no scientific reason why it can't be used. If you allowed some clever biology graduates to fill a few refrigerators with cultures and casually mix up non-sterile preparations, then they could probably run a therapy clinic as efficiently as a tattoo parlor.  Of course, America has strict cultural taboos and draconian legal prohibitions against mixing the castes in this manner - people simply accept that tattoo artists can inject people's eyes with India Ink or slit their tongues in half, but allowing people to mix up their own phage preparations is absolutely unethical and must be greatly punished. Wnt (talk) 15:10, 14 August 2010 (UTC)

Mnemonic for functional groups in IUPAC nomenclature
Is there any mnemonic by which i can memorize the priority order for functional groups used while naming carbon compounds in IUPAC nomenclature?? harish (talk) 16:57, 11 August 2010 (UTC)
 * I don't know of one, but perhaps other people have come up with an idea for the more common ones at least! The full list is very long, and includes functional groups that most chemists will never have to deal with: on a practical, professional level, it's something you look up if you need it rather than keep in your head at all times. Physchim62 (talk) 17:13, 11 August 2010 (UTC)
 * Could you start us with a list of the ones you need to know? DMacks (talk) 17:57, 11 August 2010 (UTC)


 * If your professor is making you do this for an exam, he/she is horrible. This sort of thing is something that's best left to experience, not study. John Riemann Soong (talk) 18:24, 11 August 2010 (UTC)


 * Is there no Chemists' equivalent to The Biochemists' Songbook? 87.81.230.195 (talk) 21:54, 11 August 2010 (UTC)

carboxylic acids, sulphonic acids, acid anhydrides, esters, acid chlorides, amides, nitriles & isocyanides, aldehyde, ketone, alcohol, amino, C to C double bond, C to C triple bond, halogens=nitro=alkoxy=alkyl. I am just now in eleventh grade, so these few important groups will do. If there's some error in my order, please correct it too. thanks harish (talk) 12:21, 12 August 2010 (UTC)

Sexual Behavior in the Human female
where can i read the full version of Sexual Behavior in the Human female by kinsey. preferable online. —Preceding unsigned comment added by Tomjohnson357 (talk • contribs) 17:09, 11 August 2010 (UTC)
 * This seems like a fairly complete version: the book is under copyright, so I doubt you'll do better (apart from asking for it at your local library). Physchim62 (talk) 17:18, 11 August 2010 (UTC)
 * Fixed a typo, hope you don't mind. Regards, --— Cyclonenim | Chat 17:22, 11 August 2010 (UTC)
 * Page 14 says that abstinence education turns youths into homosexuals! Comet Tuttle (talk) 19:46, 11 August 2010 (UTC)
 * (EC). There is a version on Google Books which I guess you've already found since it's the first Google result for 'Sexual Behavior in the Human female'. It isn't complete as the book appears to still be in copyright in the US where you live and likely other countries. Therefore the only place you're likely to find a complete non copyright violating copy online is on somewhere that sells ebooks (where you'll have to pay) but a quick search suggests it isn't available in such form. It should go without saying you won't receive any help here to violate copyrights. If you aren't desperate for an online copy, you could try a library Nil Einne (talk) 17:23, 11 August 2010 (UTC)

are there any ebook sites where i could pay to get the full version? --Tomjohnson357 (talk) 17:48, 11 August 2010 (UTC)
 * Barnes & Noble will sell you a paper copy for $2.25 plus delivery... Physchim62 (talk) 18:08, 11 August 2010 (UTC)
 * Well as I said above, I can't find evidence of any. Unfortunately there are still quite a lot of books which for a variety of reasons aren't available in legitimate ebook form Nil Einne (talk) 18:46, 11 August 2010 (UTC)

Buoyancy
I'm trying to calibrate my intuition about how buoyancy should work with a small amount of a fluid.

For example, consider the case of a large boat in a small lock (water transport). Archimedes' principle is that the boat needs to displace an amount of water equivalent to its weight in order to float. The boat can do that, but the lock is small enough that the amount of water remaining in it is going to weigh significantly less than the boat. Shouldn't the boat sink to the bottom, like a heavy weight overwhelming a light one on a balance beam? But then it seems like it would matter whether the lock is connected to a larger body of water, which would imply that when the door was closed off, the boat could suddenly sink - and that seems crazy.

So is there an intuitive explanation of why the amount of water surrounding the ship doesn't matter (if that's the case) which could be added to the article? This seems counter-intuitive given the pulley analogy used there. -- Beland (talk) 17:26, 11 August 2010 (UTC)


 * The quick-and-dirty thought experiment is easy: imagine the boat sailing up the canal and into the lock. While the lock's gates are open, the boat is floating in the entire volume of the river, so no problems.  When the gates close, sealing the lock off from the rest of the river, it doesn't make any sort of intuitive sense for the boat to immediately sink, right?
 * The slightly longer explanation involves looking at the situation from an energy standpoint. Imagine a container that surrounds both boat and water, with the boat afloat.  Now, think about what happens if you move the boat down into the water by a little bit.  The layer of water that was sitting happily under the boat's hull gets pushed aside, and an equal volume of water (ignoring the very slight compressibility of water) gets pushed up to sit on the old 'surface'.  Effectively, that layer of water has been lifted from under the boat up to the water's surface; doing that work takes energy.  Now where would that energy come from?  If the boat spontaneously sank when you closed the lock's gates, you'd be getting energy for free if the boat immediately sank and lifted up that water into the air. TenOfAllTrades(talk) 17:40, 11 August 2010 (UTC)


 * Taking a slightly different tack, the flaw in your scenario is that you're assuming a constant volume of water in the lock, and that's not correct. There may be a particular volume of water in the lock when it's closed and has no boat, but you don't put the boat in the lock in that state.  Instead, the boat enters when the lock is open and part of the larger system.  As Ten notes above, this is the boat floating in the whole river -- that works just fine.  When the lock closes, though, the volume of water inside has already changed due to the boat, river, and everything else.
 * Of course, the problem I'm having with this is that the scenario of "too little water" seems unlikely. If there's not enough water in the closed lock to float the boat (and assuming that water level matches that of the river), then the boat is also too big for the river.  Adding the boat's displacement to the lock makes the water level rise, not fall, and so the initial water amount isn't the limiting factor.  Instead, it's merely whether or not the boat (a) floats at all and (b) floats in the depth of water available. &mdash; Lomn 18:46, 11 August 2010 (UTC)
 * Assume that pressure is constant throughout the water. The pressure of water against the boat, and hence the nett upward force of buoyancy (see article), is the same whether the water volume is unbounded, i.e. in open sea, or bounded by lock walls that almost touch the boat. Cuddlyable3 (talk) 18:59, 11 August 2010 (UTC)


 * I think the OP's intuition is correct, it's just that the quantity of water that counts as "small" is not well-defined. Consider the extreme cases on both ends:
 * Lots of water (entire river) - boat floats. No problem, intuitively.
 * Extremely tiny quantity of water - say, a "puddle" that's only an inch deep. The boat will displace all that water under it, and raise the water level, but will hit the bottom before it has displaced enough water to counterbalance its weight.  There is no way one inch of water will be able to float the boat (unless we consider an extremely tight fit between a boat and a canal with tall walls - then a tiny fluid-layer bearing would exist between the boat and the very closely-spaced walls of the canal).
 * In the intermediate cases, the boat must displace a volume of water such that the water-mass is equal to the boat-mass. But displacing water means moving water from under the boat to the sides of the boat.  This can only work if the geometry of the water container (lock, river, etc.) is sufficient so that necessary water-volume can be moved to the side before the boat hits the bottom of the container (lock/river/lake/etc.)  If the amount of water is very small, the boat does hit the bottom.  The draft of a boat is the geometric parameter that defines this.  Boats can not sail in (locks, rivers, canals) that are shallower than their own draft.  Nimur (talk) 20:37, 11 August 2010 (UTC)


 * The scenario isn't clearly described. What do you mean by the amount of water remaining in the lock?  Are you assuming that the water goes out of the lock after it has been displaced, perhaps by pouring over the gate?  If so, then the boat will indeed sink to the bottom.  If not, please clarify what you meant. Looie496 (talk) 00:16, 12 August 2010 (UTC)


 * The amount of water remaining in the lock is irrelevant, as is any open or closed connection between the lock and a larger body of water. All that matters is the notional weight of an amount of water that has the same volume as the submerged volume of the boat. As long as this is equal to the weight of the boat then the boat will float, even if it takes up more than half of the volume of the lock. If the boat floats in the river then it will float in the any lock that is long, wide and deep enough to accommodate it. Gandalf61 (talk) 14:41, 12 August 2010 (UTC)


 * I was thinking more in the opposite direction -- if the lock is closed, the boat can float in less depth than it would normally take, because the water it displaces, having nowhere to go, may raise the water level. I'm not certain this is relevant to the question, but then I didn't really understand the question very well. Looie496 (talk) 21:35, 12 August 2010 (UTC)


 * Yes, Looie496's intuition is correct. In a lock or other "container" that has a "boat-shaped" profile, the boat can still float even though it has "displaced" less water than its own weight.  The critical weight is that of the "submerged volume" of the boat, not the actual amount of water physically displaced (i.e. moved).  The normal statement of Archimedes Principle is not quite correct in this respect.  The upthrust is actually equal to a weight of water equivalent to the submerged volume, regardless of the amount of water physically displaced.  Archimedes was right, but he was measuring overflow when he thought of water "displaced".  See the first note in the Buoyancy article.    D b f i r s   08:48, 13 August 2010 (UTC)
 * I'll just throw one more link to fluid bearing. It is possible to completely support the weight of an object using a very tiny quantity of fluid - but the parts must be almost perfectly identical in geometry.  Nimur (talk) 16:43, 13 August 2010 (UTC)
 * Mercury_bowl_and_float_of_Split_Rock_lens.jpg)]]One example is the use of mercury bowl and float type bearings for the heavy Fresnel lenses of lighthouses which use much less mercury than they "displace". -- 1.46.122.77 (talk) 00:27, 14 August 2010 (UTC)

Toxins
Can people have a gene that creates a toxin in our body? In other words is there genes that can make a toxin in our bodies? —Preceding unsigned comment added by 71.154.146.52 (talk) 17:41, 11 August 2010 (UTC)
 * I'd imagine that any gene creating a toxin with a significant effect on our bodies would have been eliminated from the gene pool. If it's a lethal toxin, everyone with it dies, and assuming this happens before they reach reproductive age (which it would, in all likelihood) then there would be no way to pass this gene on. Regards, --— Cyclonenim | Chat 17:50, 11 August 2010 (UTC)


 * Many toxins are produced within the body. Ammonia, for example. But a healthy human body has mechanisms for properly filtering them out again before they reach dangerous levels. APL (talk) 18:30, 11 August 2010 (UTC)


 * You're not talking about NDM-1, a recently-discovered gene-crossing enzyme that can cause bateria including those that infect humans to become antibiotic-resistant, by any chance? ~ A H  1 (TCU) 18:54, 11 August 2010 (UTC)
 * A gene that coded for a toxin directly wouldn't last long, since it would kill the host before they could pass it on. We have genes that produce enzymes that can produce toxins, though. For example, alcohol dehydrogenase will produce formaldehyde (which is very toxic) out of methanol. That is why methanol is dangerous. Methanol itself doesn't do much (it would get you drunk if you drank enough of it, but that's it), but it gets converted into something that does a lot of harm. (Alcohol dehydrogenase does a helpful job dealing with ethanol (drinking alcohol) and just tries to do the same thing with methanol, which turns out to be a bad idea.) --Tango (talk) 19:45, 11 August 2010 (UTC)
 * Several waste metabolic substances are poisonous if re-digested, such as undiluted urea. Does the immune system, in response to an pathogen, produce poisons at a sufficient level to subdue the pathogen, but not to seriously affect our own health. If so, can this process over-react and kill us? CS Miller (talk) 22:22, 11 August 2010 (UTC)
 * The immune system doesn't produce anything that is harmful to us. It produces antibodies but these are harmless to us, they merely seek out the pathogen. So no, it can't. Regards, --— Cyclonenim | Chat 22:29, 11 August 2010 (UTC)
 * I'd say "shouldn't" instead of "can't" and I'd cite Auto-immune disorder as my argument. The question is "can people have a gene", if there is such a thing as a gene that codes for toxin, I'd say it is possible, even if it is a disorder or mutation. If the question was "is it normal for a healthy person to have such a gene?" that's a different question. I think it's a little too simplistic to say "it would get selected out", why aren't ALL genetic disorders already "selected out" a long time ago? The subject is obviously a lot more complicated then some of the answers here suggest. Vespine (talk) 23:56, 11 August 2010 (UTC)
 * But auto-immune disorders are where your body attacks itself, it doesn't relate to pathogens. Your body can't ever poison itself when it tries to kill a pathogen. As for why all genetic disorders don't get selected out, that's very simple. The diseases which don't kill you or significantly prevent you mating can still be passed down. If a gene codes for a toxin (by definition something that causes harm and can eventually kill you) then the chances are that it will kill you before you reach reproductive age. Regards, --— Cyclonenim | Chat 00:04, 12 August 2010 (UTC)
 * I'm not sure I understand your 1st argument, how does your body "attack itself" if not almost precisely the same way it attacks a pathogen? I also don't believe your 2nd statement. Down syndrome is one of the most common genetic disorders, before modern medicine very few people with down syndrome would have lived long enough, or had the opportunity to procreate. Even today there would be very few people with down syndrome who become parents. I don't think toxin means it has to kill you, how about organisms that actually produce toxins? They have a gene that codes for it in their body right? What if you co-evolve a resistance to the toxin, isn't that what snakes do? Vespine (talk) 05:18, 12 August 2010 (UTC)

Well, your immune system can sort of kill you in response to an infection. See toxic shock syndrome. I say "sort of" because in TSS the infection is using its own toxin to trick your immune system into triggering global vasodilation so it can permeate all of your tissues. As for the original question, I don't think there's really much possibility of a meaningful answer. Too much of anything is bad for you. Tay sachs, phenylketonuria, while described as your body lacking something good, actually kill you through a buildup of compounds the body produces itself. Heck, too much water will kill you. Someguy1221 (talk) 05:34, 12 August 2010 (UTC)
 * @Vespine, when I say the body attacks itself, I mean it does so independently of any infection. Yes, sometimes, it attacks itself via the same mechanism it would a normal pathogen, but it is independant of such a pathogen's presence. The statement above my post is referring to 'when a pathogen is in our body, can we kill it off and have a detrimental effect on our bodies'. Strictly, the answer is no. There is no direct poisoning of our bodies through our own natural defenses. However, as Someguy just noted above me, toxic shock syndrome can occur, but that isn't directly a result of our own bodies. That's limited to where bacteria have toxins to trigger vasodilation. In response to your Down syndrome comment, I contest that anyone with Down syndrome would not have been able to live long enough to procreate. Down syndrome sufferers do not take any medication to prolong their lives. In fact, they have an average lifespan of around 50 years - which is more than long enough to procreate if they could. But they can't usually, and if they do it makes things more severe for the children. You assume that all diseases are simply passed down like other hereditary traits - it isn't true. Downs syndrome caused by a nondisjunction event where chromosomes fail to separate, so in that sense it's pretty much a random and rather unfortunate occurrence. Oh, did I also mention that pretty much all Downs syndrome males are infertile, and that women are often much less fertile than those without the disease? This is proof that it isn't a hereditary condition, because there wouldn't be anyone with it if it was! To address your last point, I don't really understand but I'll have a go, clearly if you develop a resistance to a toxin then that's great. You may have noticed though that we haven't. Snakes can still kill us, toxin-producing bacteria can kill us, deadly insects can... well, you get the point. We haven't "co-evole[d] a resistance" to any particular toxins other than the ones we have enzymes to digest. Seriously. Toxin infers that it's deadly or at least seriously harmful to chances of survival. Regards, --— Cyclonenim | Chat 08:09, 12 August 2010 (UTC)


 * Sorry, as an immunologist I have to completely disagree with Cyclonenim. First point: Where are the references for you bold claim that pathogens have nothing to do with autoimmunity? The true reasons for autoimmunity are not known, but one of the hypotheses that are discussed, at least for some forms of autoimmunity, is exactly the triggering by foreign antigens. These could just be "normal" allergens in the environment, but there's no reason why the defense against pathogens shouldn't be able to have the same effect (because pathogens bring a large pack of antigens with them). Next point: We are talking here about complex concepts. "Poisoning" and "Toxin" are not well defined. As someone else has pointed out, the dosis and entrance point of a substance are critical: Two molecules of a highly "toxic" bacterial protein won't kill me in my food, but if I drink some liters of pure water quickly, I will die. And what do you mean with "antibodies are harmless"? They are one of the deadliest mechanisms that our body has in its arsenal, because the adaptive immune system is constantly "evolving" to make them more and more effective. And only because we have intricate checks build into our immune system, this "weapon" does not harm most healthy humans. But in every person's blood, there are small amounts of autoreactive antibodies, because the control systems are leaky. So the exact same mechanism that destroys pathogens is constantly producing "toxic" substances. Another thing that goes into the same direction: Our macrophages use very toxic compounds, which they even store for later use, to kill other cells that they engulfed (for example reactive oxygen species and proteins that are capable to cut other proteins). In some cases, when the macrophage is unable to kill the intruder, the reaction gets "out of control" and even kills the macrophage and/or bystander cells (because both are not immune against reactive oxygen, for example).
 * And in addition, coming to the snake example, there are certainly snakes that are not immune to their own poison. They are only unaffected by their poison because the snake normally only produces and stores it in special organs, so it doesn't get a chance to get into the blood.


 * Coming back to the original question, I'd say that there's nothing in principle that could stop a gene producing a poison from working (look at all the poisonous pests around us). But as you specifically asked for people, it is unlikely that such a gene would "just show up" in a person. Humans have no use for poison, so there's no selection pressure in this direction. And complex traits as "poisonous" do not just spring into existence, they have to evolve step by step, and every step has to have a slight advantage over the previous one (or at least be neutral). --TheMaster17 (talk) 10:09, 12 August 2010 (UTC)


 * To summarize: "Can people have a gene that creates a toxin in our body? In other words is there genes that can make a toxin in our bodies?" Yes, we can and we do.  Our immune system generates powerful weapons against microbes.  One example is reactive oxygen species that are generated in neutrophils and macrophages.  The gene encoding NADPH oxidase is responsible for the production of these molecules.  --- Medical geneticist (talk) 12:24, 12 August 2010 (UTC)

Bacon crisps state 65g protein/100g
Dear Wikipedians, I was just at the store. There I browsed for some crisps/potatoe chips, and came upon a curious find: A Norwegian crisps company called Maarud sells "Bacongull" (Bacongold), and states 65g of proteins per 100g serve; 26.5g fat. Those 65g are normally carbohydrates, at least between 40-60 of them.

Am I eating some clever form of proteinized carbohydrates? Thank you in advance. 88.90.16.109 (talk) 17:42, 11 August 2010 (UTC)


 * Maybe it's pork scratchings.  Sean.hoyland  - talk 17:56, 11 August 2010 (UTC)
 * You are entirely in the right. These aren't crisps at all. Excuse me... 88.90.16.109 (talk) 18:42, 11 August 2010 (UTC)

Cold bottles freezing
Is it true there are cases when getting cold water in a closed bottle out of a fridge would cause it to freeze suddenly when opening? If yes, then how can we explain this phenomenon?--Email4mobile (talk) 18:34, 11 August 2010 (UTC)


 * The phenomenon is supercooling, and it (as well as related phenomena like superheating) results from a lack of nucleation sites on the container. &mdash; Lomn 18:36, 11 August 2010 (UTC)


 * There was a past dicussion here :.
 * The trick here is that the fridge is too cold and is cooling the water to just below freezing, but the pressure in the bottle is stopping it from actually freezing. Release the pressure and ... bang, it freezes like magic about two seconds after you open the bottle. APL (talk) 18:59, 11 August 2010 (UTC)
 * (ec) Water freezes at a temperature below 0 °C under a pressure higher than 1 atm (0.10 MPa). Therefore liquid water in a bottle under pressure could freeze when the bottle is opened. Cuddlyable3 (talk) 19:08, 11 August 2010 (UTC)
 * I can find the pressurized bottle effect makes sense in some pressurized liquids, but not sure if water bottles are pressurized too since we expect vapor pressure to get lower as well by decreasing temperatures inside the fridge. --Email4mobile (talk) 19:30, 11 August 2010 (UTC)
 * Look at the phase diagram under Ice. The effect of even a 10000-fold change in pressure is only a 2-3 degrees C difference in the freezing point.  Whatever the bottle is pressurized to, we're only looking at a fraction of a degree that the water would have to be within for the simple release of pressure to freeze it.  You might heat it up by as much as that before you get it open.  So I think it's far more likely that bubbles generated by moving the bottle, or contact with small irregularities, would nucleate freezing in the supercooled liquid. Wnt (talk) 15:22, 14 August 2010 (UTC)
 * The OP might be interested in a similar question asked three weeks ago Reference_desk/Archives/Science/2010_July_26. CS Miller (talk) 22:09, 11 August 2010 (UTC)
 * A few years ago I had a habit of putting a 1 liter bottle of water in the freezer before going on my lunch break (1 hour). Upon returning, I retrieved the bottle and was able to observe the effects of supercooling by tapping the bottle with my fingertip.  Hemoroid Agastordoff (talk) 16:43, 13 August 2010 (UTC)

is this apoptosis or autophagy (cellular)? Is it even programmed cell death?


My lab group just called this process whenever it occurred apoptosis but they're chemists (though they are branching out into the biology side), not cell biologists. Is autophagy a more accurate description? I don't see a description of these very visible bubbles in the apoptosis article.

This occurs whenever the cell culture is about to die on the microscope slide after having been on the slide for too many hours, at room temperature, without the 5% carbon dioxide atmosphere. John Riemann Soong (talk) 19:45, 11 August 2010 (UTC)

(I notice that the images in each of these articles are either cartoony or not very vivid, so I want to include this photo in one of the articles, but I don't know which one is appropriate.) John Riemann Soong (talk) 20:45, 11 August 2010 (UTC)
 * Pardon me, but you seem to have been putting these types of photos up and asking extremely detailed questions regarding cell structure and function, the likes of which can probably only be answered by individuals with such highly specific training that you are unlikely to receive a good response on the ref desk. Good luck, though!  DRosenbach  ( Talk 20:47, 11 August 2010 (UTC)
 * Can you even tell which it would be from this photo? I was under the impression that either footage or a series of pictures over time is/are needed to determine which type of PCD is happening. Can't you tell which type is happening by observing what features degrade first? In autophagy, the nucleus should go towards the end. I also agree with DRosenbach above. These questions are pretty complicated and I'd take a guess that people at your University (in the biological and medical departments) may be better off answering your questions. Regards, --— Cyclonenim | Chat 21:29, 11 August 2010 (UTC)


 * Well I'm very familiar with the bubbling process. I've watched it happen like a million times. People identify very peculiar and specific insects I've never heard of all the time, so why not something as basic as a fundamental cellular process? Anyway, the nucleus takes a while to degrade -- the bubbles appear first -- before the cell blebs. Over time these bubbles can "take over" the cell. I'm not sure if apoptosis is triggering the hypothesised autophagy or vice versa. I think it this process is a consequence of nutrient or oxygen starvation.


 * Should I be bold and just put this photo in the autophagy article? John Riemann Soong (talk) 21:35, 11 August 2010 (UTC)
 * Perhaps have a go at posting it at one of the WikiProjects first and see if someone can help you there. There's no rush :) I'd agree that it looks more like an autophagical process but it's hard to tell, as you mentioned, if it's being performed under the 'supervision' of a larger process. Regards, --— Cyclonenim | Chat 22:20, 11 August 2010 (UTC)


 * The best way to be sure would be to fix and immunostain the cells to look for specific markers for autophagosomes; microtubule-associated light chain 3 (LC3) associated with vesicle membranes is one of the popular markers in mammalian cells . Meanwhile, you can look for the activation of apoptosis machinery in the cells by staining for cleaved caspase-3.  It is apparent that there are some sort of perinuclear vesicles in those cells, but I would be hesitant to jump to conclusions about their identity.  TenOfAllTrades(talk) 22:36, 11 August 2010 (UTC)

Burping in zero gravity
A while ago I needed to burp while lying down. I could not do it, I imagine because the bubble of burp-gas must be in contact with the upper sphincter of the stomach. In gravity this is no problem. But what do astronauts do in space? Google searching has not come up with any serious answer. Thanks. 92.15.14.45 (talk) 21:36, 11 August 2010 (UTC)
 * This article (towards the bottom) suggests that astronauts can burp in space, but since the gas isn't necessarily at the top of the stomach, it comes out as an unpleasant wet burp. anonymous6494 02:45, 13 August 2010 (UTC)

In other words it would be like a mini-vomit. No wonder NASA have kept quiet about it. 92.29.127.240 (talk) 15:11, 13 August 2010 (UTC)

Impact of piping on water quality
I asked a similar question here, but I figure this is more of a science question. The question is - if the water is pure when it is pumped into water supply system, can it get contaminated while it travels through piping (i.e. by something in the pipes, not foul play) ? Xil (talk) 22:15, 11 August 2010 (UTC)


 * City water supplies are continually scoured by the flow of water so there is no opportunity for bacteria to establish a stationary colony in the pipe and contaminate the water flowing through. Where water lies stagnant in a pipe for a long period of time, such as in unoccupied houses, there is a risk of colonies of bacteria becoming established and contaminating the initial throughput of water  when flow resumes.


 * The major risk of contamination of a city's water supply is contamination at the point of collection (such as a dam) or prior to collection if there are contaminants in the catchment area (such as a dead animal.) Dolphin  ( t ) 22:40, 11 August 2010 (UTC)


 * Older homes and some older municipal water systems may use lead solder and even segments of lead pipe. Water that is left standing for an extended period (several hours or overnight) may pick up a toxic level of lead.
 * Biological contamination is rare unless the pipes are damaged close to the end user and external organisms are able to contaminated the drinking water. (This is rare and rather difficult to do, as the water in the pipe is generally being forced out under pressure.)  As well, in many municipal water systems water is treated with chlorine or chloramine; the latter compound in particular tends to persist for several days in the water, providing a residual disinfectant activity all the way out to the consumer's tap.  TenOfAllTrades(talk) 22:56, 11 August 2010 (UTC)
 * Your note about lead reminded me - I read somewhere that piping for drinking water used to be made from copper to improve its quality, is any particular metal used or other material used for same purpose today ? Also asumtion here is that piping is old (not leaking old, but I figure pipes could be rusty, there could be some sediments or stuff growing on wals of pipes or something). Aside from being curious about water supply systems in general I am also concerned about water I am drinking, I found out that my city has two water sources. One is river water which is treated with aluminium sulphate, ozone and light dose of chlorine before it is pumped to consumers. However I live in another part of city which uses ground water taken from soils rich with iron and manganese. My issue here is that despite very good taste, I feel a light, but foul smell when drinking Xil  (talk) 08:37, 12 August 2010 (UTC)
 * Most of the piping in my own house (UK, about a century old, but repiped some time since the initial build) is copper, which was the default material in the UK at least until quite recently and is certainly still used for repairs. Plastics of some sort might be used in new buildings now, but primarily for cost rather than health reasons, copper being increasingly in demand for other purposes, and therefore increasingly expensive.
 * In the UK and, I think, most First-World countries, water supply companies are legally obliged to deliver drinkable water to customers, and are responsible for the pipework right up to the latter's property line - they would be heavily penalised if they failed to do so whether due to pipework contamination or for any other reason. Certainly water from different sources can differ in its trace elements as well as the treatments it has undergone to ensure it is potable, and this will be detectable in the taste and smell, which is partly why, for example, many breweries in the UK "Burtonise" their brewing water (or "liquor"), adding trace elements to make it more like the natural supply in Burton-on-Trent*. Different people find these different tastes and smells variably noticeable, innocuous or sometimes unpleasant, but unless something has gone wrong, they do not usually signify any health hazard. However, such factors are so variable from country to country that it is impossible to safely generalise for an unspecified locality.
 * (*As well as effecting the immediate taste to humans of the water component of the beer, the trace elements also influence the metabolism of the fermenting yeasts - but I digress.) 87.81.230.195 (talk) 12:14, 12 August 2010 (UTC)
 * In terms of sediment and stuff settling in the pipes, I don't think this is likely to be a significant problem due to the constant water flow. In Malaysia, when you get a water cut, you will find the water is dirty when it first starts flowing again. I'm not sure if this is from the pipes or the supply but I think it is the former as the water flowing again dislodges stuff that has settled and/or any oxides or whatever from the pipes Nil Einne (talk) 14:18, 12 August 2010 (UTC)
 * Yeah, they are legaly required to deliver clean water up to property line, however city's pipelines are known to be very old, so I'm not complitely sure that they can. Anyways, I don't feel any smell anymore and judging by what it smelled like I figure it could have been from water having stayed in pipes too long. Thank you for the answers Xil  (talk) 09:45, 14 August 2010 (UTC)

Antibiotic-resistant "super bug"
I just saw a story on the news about a "super bug" that's resistant to all known antibiotics and can spread this immunity to other bacteria. What research has been started to combat this before it causes the extinction of humanity? --70.134.48.188 (talk) 22:17, 11 August 2010 (UTC)
 * Firstly, don't listen to everything the news tells you. Yes, it's a fairly big blow for antibiotics but not absolutely condemning for all of humanity. Not just yet. What happens is that it prevents any antibiotic with β-lactam rings from working, but this protein that's causing all the havoc is only present in certain, limited Gram-negative bacteria (such as E. coli and others) so far. It could spread and become more common, but it hasn't yet. Other Gram-positive bacteria can still be treated, so contrary to popular opinion, it's not the end of antibiotics completely. There are currently no drugs in the pipeline (or at least pre-clinical stage pipelines) that are able to combat this obstacle, but that doesn't mean we're completely hopeless at finding another. One option, as I posted a question about above, could be to develop phages that actively hunt and kill off bacteria, but they are currently not approved for human, medicinal use. It is not the end of the world... yet. Regards, --— Cyclonenim | Chat 22:24, 11 August 2010 (UTC)
 * What about Augmentin?  DRosenbach  ( Talk 14:59, 13 August 2010 (UTC)
 * What about it? It's a B-lactam antibiotic, so it wouldn't work on any bacteria with this new gene. Regards, --— Cyclonenim | Chat 18:35, 13 August 2010 (UTC)
 * What "super bug" in particular ? In any case the bacteria evolve so they eventualy are resistant to older drugs, therefore new drugs need to be invented. This happens all the time, "super bug" is just media hype. One such "super bug" case was the recent swine flu pandemic. Xil  (talk) 22:34, 11 August 2010 (UTC)

They said it's a bacterium that's completely immune to all known antibiotics. --70.134.48.188 (talk) 22:36, 11 August 2010 (UTC)
 * What I meant was it does it have a name other than "super bug" ? If not it may very well have been a speculation that such "super bug" may emerge, not that it is currently infecting people (if it was and it wasn't contained we would see broader media coverage) Xil  (talk) 22:52, 11 August 2010 (UTC)
 * New Delhi metallo-beta-lactamase. -- BenRG (talk) 23:22, 11 August 2010 (UTC)


 * Let me clarify: it is not a super bug. It's a super plasmid. It accounts for resistance to any antibiotic that replies on beta-lactam rings (which is a lot of them) and is currently spreading around through various mechanisms I won't bother to go into. However, it's only relevant to specific bacteria called Gram-negative bacteria. Antibiotics that currently work on Gram-positive bacteria will still work (for now). We may even develop new ones for Gram-negative bacteria. The media is lying when it says it's the end of all known antibiotics. Regards, --— Cyclonenim | Chat 23:38, 11 August 2010 (UTC)


 * Another thing to bear in mind before writing off the human race is that the vast majority of bacteria (including those bearing exotic plasmids) are completely harmless to us. Bacteria that are either fatal or seriously harmful tend to evolve to be less nasty because if the host dies or becomes so sick that they go to bed and stay there, the bacteria have a much harder time spreading.  From an evolutionary perspective, the optimum thing for the bacteria to do is to be massively infectious - yet produce as few symptoms as possible. Sure, when a new disease pops up, a good percentage of the population might die before that happens - but it's hard to imagine a scenario where that would take out more than a few percent of the worlds population.  When you look at some of the worst pandemics in history - the 1918 flu pandemic, for example. Over the course of two years, one third of all people in the world were infected and 3% of the world's population died.  There were absolutely no drugs that could to a thing to prevent it.  The disease never was 'cured'.  The pathogen simply evolved to be less obnoxious all by itself.  Certainly a 3% death rate would be a monumental disaster - but (as you can tell from the 1918 event) the long term effects on humanity are minimal and the worst disease epidemic in history is barely even talked about, 90 years later. SteveBaker (talk) 03:34, 12 August 2010 (UTC)
 * Is that true? I'm unsure. I know it definitely applies to viruses, because they are, in a literal sense, parasites which invade our cells. If the cell dies (without it bursting), then they can't replicate and spread. Bacteria, however, aren't parasites. They invade our blood and tissues but they don't strictly interact with the cells, do they? Might be wrong. Regards, --— Cyclonenim | Chat 07:52, 12 August 2010 (UTC)
 * I don't think notion that disease cannot have long term effect on civilization is entirely true - the plague apparently did, though the death toll was higher than 3% ofcourse (still if people survived plague pandemic in age when health care was less developed, why wouldn't people survive now ?) Xil  (talk) 08:49, 12 August 2010 (UTC)
 * We do have examples, though, of basically entire civilizations being killed off by pandemics, e.g. the Native Americans, who under some estimates had 95% of their population killed by Old World viruses to which they lacked immunity. That's a pretty extreme scenario, but it's pretty hard to contemplate. Even 33% is a ridiculously high number, and would have massive effects on human civilization and society (as did the Black Plague on Europe). If you're willing to say that's OK because life will be different/better/go on, you might as well say that nuclear war is fine too, because those are the kinds of numbers we are talking about. --Mr.98 (talk) 12:51, 12 August 2010 (UTC)
 * Well, it's obviously not "fine" - but the point is that it's also not "the extinction of humanity" - which is what our OP is asking about. SteveBaker (talk) 14:10, 12 August 2010 (UTC)
 * Keep in mind, the bacteria still needs to be able to gain entry into the body to be harmful. We have many layers of innate resistance to microbes (see innate immune system), none of which are affected by bacterial acquisition of antibiotic resistance.  According to BenRG's helpful reference above, many of the people who have been infected by these super-organisms were "infected by NDM-1 carrying bacteria while undergoing surgery under non fully-aseptic conditions."  This means that the "super-bug" is largely responsible for nosocomial infections, certainly nothing like a "pandemic" that can somehow spread from person to person.  It is another in a long example of antibiotic resistances that bacteria have evolved over the millenia.  Where did we first get antibiotics from?  mold.  How long have bacteria and molds been fighting with each other?  This is evolution in action and we are only recent players.
 * I'm not trying to downplay the devastating effect of antibiotic resistance on the way that medicine is practiced today, but you have to realize that the media is going to hype up this kind of thing to sell their product. This latest version of the "super-bug" is not going to cause the end of our species. --- Medical geneticist (talk) 12:40, 12 August 2010 (UTC)


 * An antibiotic-resistant "superbacteria" can cause a major pandemic with many casualties, but it will not drive humanity to extinction. Remember that we only have antibiotics since not much more than a hundred years ago: so people before it had to deal with illnesses having no antibiotics at all. A lot of people might die, but it's very far from extinction. --131.188.3.21 (talk) 23:49, 12 August 2010 (UTC)


 * NDM-1 isn't really "super", nor is it a "bug". It's an enzyme that gets into different types of bacteria and makes them immune to antibiotics, similarly to how disinfectants that kill 99.99% of bacteria and viruses leave the remaining 0.01% mutating into superbugs that over several cycles become completely resistant to antibiotics and disinfectants. It's not that the bacteria infected by this "superbug" become extra deadly, they just become much harder to kill. So if it found itself preferring a bacterium that has a high mortality rate in humans and quickly spreads in those bacteria, then we might have a problem. The real pandemics like the Black Death and the more recent 1918 flu pandemic were devastating, but the recent pandemics have been not that severe, although the melting of glaciers and permafrost in Arctic regions could release ancient viruses in the future. ~ A H  1 (TCU) 00:21, 13 August 2010 (UTC)

Bacteria have been living on Earth for about 4 billion years in all sorts of environments. Complex life forms have been around for a much shorter time and the environments they can live in is far more limited. Surely, then the massive use of anti-biotics is a stupid, self-defeating strategy as eventually you'll end up with superbugs that are only sensitive to drugs that are lethal to humans? Count Iblis (talk) 15:14, 13 August 2010 (UTC)
 * Probably, but it's good for saving lives in the meantime. There's no guarantee that bacteria will develop resistance because, like natural selection, you have to have the mutation occur first. If it doesn't happen, obviously you'll get no resistance. The reason resistance is currently so common is because a lot of our antibiotics only vary slightly. There are different classes, but within those classes the variation is limited, so there isn't much work needed to accidentally develop a resistance to a new antibiotic. Regards, --— Cyclonenim | Chat 21:15, 13 August 2010 (UTC)

The Soviet Union developed a reasonably effective alternative, phage therapy, which is banned in the U.S. because of political or economic inconvenience to the capitalist system. Hopefully, by the time the first 90% have died, people will reconsider their ethics. Wnt (talk) 14:59, 14 August 2010 (UTC)