Wikipedia:Reference desk/Archives/Science/2009 October 10

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October 10

Inbreeding

Is there anyway to prevent the negative effect of inbreeding in the South China Tiger? All captive South China Tiger today descend from 2 male and 4 female caught in the 1950s and 1970s. What if there weren't any wild ones left to breed with? Is there anyway for an inbred animal to continue on --Queen Elizabeth II's Little Spy (talk) 03:48, 10 October 2009 (UTC)

Lines exhibiting inbreeding depression can be weeded out via evolution. Genetic diversity will just have to start afresh. I think that the entire human race was once at a bottleneck population of 10 individuals, from what DNA evidence tells us. John Riemann Soong (talk) 04:47, 10 October 2009 (UTC)

According to Population bottleneck#Humans, the human population dropped to a few thousand, it doesn't mention any bottleneck as extreme as 10 individuals (and excludes a bottleneck of a single breeding pair). --Tango (talk) 18:41, 10 October 2009 (UTC)

That is a bit of a leap JRS. The whole present genepool may easily be entirely descended from 10 individuals without them being the only population at any instant. The population being at ten for humanity on the planet seems on balance less likely than that a particular group which only had ten members went on to being the only surviving population without interbreeding... --BozMo talk 10:34, 10 October 2009 (UTC)

Closer to home, Cheetahs also have very low genetic diversity, again interpreted as indicating a past genetic bottleneck event. In the case of the South China tiger, it is likely the South China Tiger Project is following procedures previously applied in breeding other endangered species, whereby potential captive breeding pairs are carefully selected from the individuals available in zoos worldwide so as to maximise genetic mixing within the available gene pool (the article hints at this), and will presumably also release animals back into the wild in locations calculated to maximise the likelihood of similarly diverse uncontrolled matings. 87.81.230.195 (talk) 07:30, 10 October 2009 (UTC)

Note that while inbreeding can be bad, in that it can cause reduced resistance to disease and other defects, that it isn't always bad, if the animals you start with are genetically healthy and different from one another. It can even lead to better breeds, if genetically unhealthy animals are prevented from interbreeding with the healthy ones. With the advent of genetic testing, it may be even easier to determine which animals would make the best breeding stock. StuRat (talk) 16:53, 13 October 2009 (UTC)

Yawning phenomenon

Why do people usually yawn simultaneously ? —Preceding unsigned comment added by 113.199.155.180 (talk) 04:02, 10 October 2009 (UTC)

Yawning is infectious. Rkr1991 ^{(Wanna chat?)} 04:19, 10 October 2009 (UTC)

That's just restating the question. Why is it "infectious"? --Anonymous, 04:51 UTC, 2009-10-10.

No, it's providing a link to a wikipedia article, wherein one can read about the topic of the question. It's not clear why the questioner evidently didn't look in this most obvious of places, or if so, what particular information there was unclear. DMacks (talk) 05:33, 10 October 2009 (UTC)

I looked at the article. Did you? It doesn't answer the question, just makes a flat statement that "yawning has an infectious quality... which is a typical example of positive feedback", in humans and chimpanzees. --Anonymous, 18:05 UTC, 20009-10-10.

Maybe try reading the whole article next time? There's a whole section dedicated to it Yawning#Contagiousness. Perhaps it could be more detailed but it seems to give the right idea which is as discussed below that we don't know, there are lots of hypothesis. Incidentally, I do feel that Rkr1991's answer was poorly phrased since it wasn't that clear to me he/she was saying to look at the article (although I also agree the OP ideally should have looked at it first and then came here with any further questions). Nil Einne (talk) 05:56, 11 October 2009 (UTC)

Apologies. I searched ahead for other mentions of "infectious" but it didn't occur to me that the article would switch to using a different word part way through. --Anonymous, 20:10 UTC, October 11, 2009.

Short answer to "why is yawning infectious?" - research is ongoing, several possible explanations have been proposed, but none of them has yet been shown to be correct. Indeed, there is no general agreement on why people or other creatures yawn at all. 87.81.230.195 (talk) 07:11, 10 October 2009 (UTC)

:::Though I do know that just reding this made me yawn.:-)209.244.187.155 (talk) 12:28, 10 October 2009 (UTC)

For the same reason that people laugh together. We're just very very social creatures and what one person does influences everyone else in remarkable fashion. Vranak (talk) 23:23, 10 October 2009 (UTC)

Well, none of these really answer the question. The truth is that the answer is simply not known. There are a lot of speculations about the mechanisms and functions of contagious behaviors, but very little in the way of cold hard facts. The existence of mirror neurons (which is controversial itself) probably has something to do with it. Looie496 (talk) 00:03, 11 October 2009 (UTC)

I agree that we don't have an answer for this one. However, I believe the "mirror neuron" theory of yawning is busted. I forget where I saw that - but the existence of people like myself with Asperger's syndrome or Autism (which is in part a manifestation of the lack or malfunctioning of mirror neurons) provides an easy test. I certainly get caught up in the infectious yawning thing - yet I'm completely useless at picking up what other people are thinking. The infectious nature of yawning is obviously happening at a deeper level than things like copying other peoples body language when you agree with them. The most convincing explanation I've heard is that yawning is pre-linguistic communication (like laughing) and it comes from deep in our evolutionary past. The meaning is thought to be something like "we all need to switch activities right now", so when one person yawns, the other people yawn back to indicate that they understood the message - so pretty soon everyone in the group has seen the message. Moving from an activity to sleeping is just one of those things that we all tend to do together. I think it's significant that even talking about yawning makes one want to yawn - and reading a joke can make you laugh - which suggests that perhaps our higher level language abilities still have connections back to this pre-language stuff. SteveBaker (talk) 03:56, 11 October 2009 (UTC)

Our article seems to claim the opposite: "A 2007 study found that young children with autism spectrum disorder do not increase their yawning frequency after seeing videos of other people yawning, in contrast to typically developing children. This supports the claim that contagious yawning is based on the capacity for empathy.[24]" Nil Einne (talk) 06:00, 11 October 2009 (UTC)

I kid you not - I went to the yawn article, which I had never seen before, and started yawning as soon as I saw the illustration. Although it might just be mother nature telling me it's time to pack it in for the night. →Baseball Bugs ^{What's up, Doc?} carrots 08:05, 11 October 2009 (UTC)

I didnt even get that far, this topic got me yawning. Livewireo (talk) 17:13, 12 October 2009 (UTC)

To some degree, yawning, laughing, and vomitting are all contagious. ~AH1^(TCU) 13:47, 11 October 2009 (UTC)

thermodynamic resonance stabilisation

They always tell me that delocalised charge => more stable, and intuitively I can see why. But what is the rigourous explanation why? Does it relate to entropy and the distribution of energy among more microstates? John Riemann Soong (talk) 04:45, 10 October 2009 (UTC)

Rigorous explanation. Hmm. Ultimately the only rigorous explanation comes from the quantum mechanics equations, which do not map reversibly onto the English language. As with so much of physics and the world the "characterisation" we use is just a way of looking at it not per sae rigorously true, because whichever way you do it is a simplification. The way I look at stability is in terms of intermediate energy states (in a quasi-static kind of way). Dislocalisation must have a more favourable Gibbs free energy or it would not happen but stability is more to do with how much of the structure (bonds etc) you have to disrupt to get to a reacted state and how big a hill that is to climb. The intermediate radicals are generally a big distortion. Put it another way, if you say you understand it intuitively then you understand it. --BozMo talk 06:45, 10 October 2009 (UTC)

I consider more that electron delocalization (the resonance itself) is what increases the stability. Charge is just an artifact or result of the electron distribution, not the actual/primary feature that is delocalizing. LCAO is a convenient way to look at the electronic structure and see which atoms are electron rich vs poor. For example, allyl cation valence electrons are spread across all three carbon atoms but C2 provides more orbital contribution as this is the most constructive overlap (the σ looks like oOo). So C1 and C3 are relatively electron-deficient and σ is symmetric, so "a bit of a positive charge equally on each those positions". DMacks (talk) 07:09, 10 October 2009 (UTC)

With regards to reactivity my rationalisation is that for example, it's harder for electrophiles to "attack" delocalised negative charge and nucleophiles to attack delocalised positive charge, but that's of course based on my intuitive understanding. In my mind I still have Gauss' law enclosed charge mixed up with all these other concepts.

Okay, let's take say, reactivity of esters and amides towards nucleophilic substitution. So in simple terms, if Nu: attacks, it's harder to attack delocalised charge (especially if it's delocalised on the electrophilic carbon!) and you break resonance stabilisation and so on. But in reality, what is going on? Do the pi electrons move onto higher energy orbitals? John Riemann Soong (talk) 07:21, 10 October 2009 (UTC)

You are not talking about discrete particles, but wavefunctions. I would caution you not to think too much in terms of "in reality". Trying to understand a complicated function (whether in Quantum Electronics or Fluid Dynamics or whatever) as though the truth was in the words and concepts and the equations were subservient to that will get you so far but as you get more into research it will not help you. I assume from the questions that you are approaching the point of becoming a researcher rather than just learning. SO you need to know the reality is the (huge continuous) data set, just like the universe is an imaginably big data set. All mental concepts (especially when refering to electrons as discrete particles) are at the very best only convergent to truth if you allow an indefinitely long description, or you work in a massively irreversibly compressed data set (such as the conceptual framwork we use for everyday life). That fact that short descriptions ("physical characterisations") work so well sometimes is remarkable, and working by concepts and patterns is a powerful way forward. But it does not make the descriptions "in reality". --BozMo talk 08:59, 10 October 2009 (UTC)

ring formation

I am quite frustrated by my class, because ring formation is presented as such a trivial step (and generally presented with hand-waving) when it my mind, it puzzles me. I know rings are unsaturated and that 5 or 6-membered rings are the best, but is there some big summary article that covers all the basic aspects of ring formation, driving forces, mechanistic geometries, stereoselectivities, etc. so I don't get tripped up on exams?

It's frustrating because I know the C-C bond forming mechanisms and everything goes well with linear molecules but I simply get tripped up by the sudden transition to rings. John Riemann Soong (talk) 06:33, 10 October 2009 (UTC)

The real key is that rings aren't intrinsically "different" from non-rings. An intramolecular reaction is just two reactive components that happen to be attached to the same skeleton rather than two separate skeletons. What a ring does is constrain the motion or geometric possibilities of the reaction and add some structural concerns regarding stability. By looking at how the reactants are arranged in their reactive conformation and one can often see the same structure/stability issues as in the product. Intramolecularity also affects reaction rate: faster if two reactive centers are constrained to be near each other in proper reactive conformation, slower if they are constrained to be unable to approach each other for reaction mechanism. If you know 5 and 6 are stable ring sizes, then forming them is relatively easy, whereas other sizes are harder to close and/or more likely to undergo ring-opening reactions. Cyclohexane covers details of the stabilities and conformations of that ring, so, for example, it will be hard to close a cyclohexane if the reactive conformation involves having a sterically large group in an axial-like position. It doesn't matter if the ring itself is actually closed--the stability issue is based on local conformational effects. DMacks (talk) 06:53, 10 October 2009 (UTC)

Okay what's a good way to efficiently predict whether a substituent will be axial or equatorial? Are you expected to work out all these conformational combinations in your mind? Is it time to bring back the model kit?

Also, are there any rules of thumb for positioning reacting groups during a retrosynthesis? Sometimes I know I essentially need electron donating and electron withdrawing sites but my major problem (with rings) is getting them to fit on a small molecule without them being too far away or too close, and then I need to make sure my electron withdrawing group or electron donating group doesn't interfere or can be eliminated or reduced/oxidised conveniently at the end of the (pencil and paper) synthesis. Any tips? John Riemann Soong (talk) 07:10, 10 October 2009 (UTC)

The first tip is: practice. The more experience you have, the more efficiently you can analyze a structure and recognize it as fitting a pattern you know.

There is often no really foolproof way except to try lots of possibilities to see what looks good enough and has no obvious flaws. Try lots of different retrosynthetic disconnections. Look at many different aspects of a proposed starting material (and especially try to find reactions other than the one you want) and then decide which ones have structural or mechanistic problems and also which ones have more than one particularly good kinetic/thermodynamic effect. The real issue (and one that plagues every synthetic chemist!) is avoiding tunnel vision (seeing what you want to happen rather than some other possibility). Real chemistry is hard precisely because nature is even cleverer than we are, and can find the one reaction or structural special-feature we neglected to notice, or even a previously completely unknown "better" reaction than the one planned via retrosynthesis. On-paper is easier, and school-work is easier still because you only are expected to know a limited set of reactions.

The second tips is: for geometry, it's almost always time to bring out the model kit unless you can visualize and diagram well (i.e., you rapidly get correct answers:) in 3D. If you are making a cyclohexane, draw the starting material in the same conformation as the product--maybe start by drawing the product and then erasing the bond being formed in the reaction. If you have studied cyclohexane conformations (most orgo texts devote many pages and maybe even a whole chapter to this specific topic!) you definitely know "axial is awful". Well not always because there could be other competing effects), and sometimes only "a little worse" (depending on what group is axial and because other conformations could have other instabilities). If you haven't looked at cyclohexanes lately, time to go back and reread. Or if you haven't learned that section yet but are at least expected to know about conformational effects, you can look at models and check for eclipsed and gauche interactions (the whole cyclohexane conformations topic is just a specific application of those same fundamental effects).

The third tip is to practice. A lot. And then some more. There are rules-of -thumb for every reaction type, and certain types of structures "look like the product of a certain reaction" or "doesn't look like the product of a certain reaction" once you're familiar with the reaction. The ring positions of the donor and acceptor groups in Diels-Alder and electrophilic aromatic substitution reactions have particularly clear patterns. But all that can't be taught directly except by studying the reactions. DMacks (talk) 07:50, 10 October 2009 (UTC)

"Predicting" stable configurations is the realm of molecular dynamics - which is a heavy-duty supercomputing-scale problem. A lot of empirically observed configurations are known to be stable; it's a difficult task to work out from first-principles of atomic interactions why these geometries would actually have a lower energy. Nimur (talk) 13:49, 10 October 2009 (UTC)

h1n1

Moved from Talk:2009 flu pandemic

iam having touble getting out bed when lying down plus it hurts to cough an sneenze my chest feels like some one hit with a hammer —Preceding unsigned comment added by 173.81.224.6 (talk) 07:11, 10 October 2009 (UTC)

We do not give medical advice, please go to a doctor.--Stone (talk) 07:48, 10 October 2009 (UTC)

Oh yes? And what about the advice sought for the Chinese Tiger above I don't see you up there.

Answers to a question about the inbreeding issue of the South China Tiger do not constitute medical advice under the terms of our guidelines. On the other hand, directly diagnosing a set of symptoms in some actual, specific, living person is flat out not allowed. Please read: Wikipedia:Reference_desk/guidelines#What_the_reference_desk_is_not...with special reference to the third bullet point. Any debate about that belongs on our discussion page, not here. SteveBaker (talk) 17:38, 10 October 2009 (UTC)

Person posting the question, you are describing a person who is ill. You can only get good explaination from a doctor. You could be experiencing anything from flu to broken ribs or pure imagination. GO TELL DOCTOR Preceding medical advice given by ~ R.T.G 12:15, 10 October 2009 (UTC)

Wikipedia gives medical advice, it is, go and see a doctor or other qualified professional. ~ R.T.G 12:15, 10 October 2009 (UTC)

Mushroom from Virginia

If found these mushrooms beneath a pine tree in Virginia south west of Washington, does anybody know what they are? I think they look similar to a Amanita muscaria but without the red colour. Thanks--Stone (talk) 07:47, 10 October 2009 (UTC)

Maybe Amanita cokeri, if so the article is in need of a picture. Mikenorton (talk) 08:10, 10 October 2009 (UTC)

or Lepiota cristata. What is the smell like?--BozMo talk 09:31, 10 October 2009 (UTC)

Looks a lot smaller than the ones I saw. 20 cm (7 inch) was the diameter of the largest ones. Amanita muscaria I found here in europe look most like those I found in Virginia.Amanita smithiana and Amanita solitaria look also not that different.--Stone (talk) 10:58, 10 October 2009 (UTC)

Very difficult to identify the actual species without information that we don't have, e.g. in A.cokeri the shape of the bulb and the spores is diagnostic[1]. The cap size can be up to 15 cm (6 inches), so not much smaller than the ones you saw. The location is right, oak-pine forests in the eastern USA, but that doesn't settle it. On the other hand A.solaria is only found in Europe, A.smithiana is found in the Pacific Northwest and Lepiota cristata is much too small (max. cap size = 5 cm). Mikenorton (talk) 11:50, 10 October 2009 (UTC)

Sorry! I thought that Lepiota cristata is too small, but Amanita cokeri is OK. --Stone (talk) 14:43, 10 October 2009 (UTC)

Ah yes, I see now that you were replying to BozMo, doh! Mikenorton (talk) 15:43, 10 October 2009 (UTC)

sugar D M

I am suffering from sugar since 24 years ago. I used to take insulin twice a day 76 units. My doctor discovered sever inflammations in my stomach (CURED NOW) and tests revealed that my pancreas is working with a capacity of 80%. Im taking 50 units of insulin in the morning and 500mg metformin HOL 3 tablets daily plus a tablet of Galvus Vidagliptin 50mg. Some times my suguar level becomes lower than 100mg! I want an explanation and if there is a cure. thanks —Preceding unsigned comment added by 188.161.163.247 (talk) 09:12, 10 October 2009 (UTC)

We do not give medical advice, please go to a doctor.--Shantavira|^{feed me} 09:42, 10 October 2009 (UTC)

He/she asked if there was a cure for diabetes and how exactly the problems occur. No advice sought here. ~ R.T.G 12:07, 10 October 2009 (UTC)

He/she wants a medical explanation for their specific insulin results. We can't help with that, it's something they need to speak to a doctor about. — The Hand That Feeds You:^Bite 18:39, 12 October 2009 (UTC)

The Wikipedia article on diabetes may be of some help in explaining your situation. --Phil Holmes (talk) 12:13, 10 October 2009 (UTC)

Nutritional value of nut

Hi, if you ever kept birds you are always feeding them seeds and nuts. Birds are high octane creatures. Is the nut a really good all round food or? How do nuts in general match up to fruit in general? Is there a kind of nut that is especially good for us the way soya is in beans? ~ R.T.G 12:04, 10 October 2009 (UTC)

In general, the macronutrient profile of nuts and fruits are very different.

Nuts are very calorically dense (lots of calories per gram), and provide most of their calories in the form of fats. The fats in nuts are at least primarily the "good" unsaturated fats, not the worse saturated fats. Nuts are also quite high in protein, and indeed generally have even more protein than beans on a per-gram basis, although less than beans on a per-calorie basis. Little of the calories in nuts comes in the form of carbohydrates.

Fruits are much less calorically dense than nuts, and provide most of their calories in the form of carbohydrates (starches and sugars). On a per-calorie basis, fruits generally have less protein than any other category of whole food, and they're very low in fat.

In terms of vitamins, nuts would tend to be better in terms of the fat-soluble vitamins like A, D and E, and fruits would tend to be better in terms of the water-soluble vitamins like C or the B vitamins.

Nuts are certainly a healthy food, when eaten in moderation, but I'm not aware of any specific nut species being exceptionally good for us. Eating too many nuts would be bad, though, because it'd be easy to get fat from them due to the high caloric density. Red Act (talk) 12:57, 10 October 2009 (UTC)

Very good answer Red Act thank you ~ R.T.G 18:01, 10 October 2009 (UTC)

One other diff, nuts are lower in water content than fruit. Thus, while a fruit-eating bird may not need any additional water (except maybe for bathing), a nut-eating bird likely will. StuRat (talk) 16:36, 13 October 2009 (UTC)

Clouds over Moscow

This looks very strange: [2] - What could cause it and why is it such a good circle? Thanks for info. --AlexSuricata (talk) 14:31, 10 October 2009 (UTC)

Possibly a type of fallstreak hole? Karenjc 14:38, 10 October 2009 (UTC)

If you want seriously weird clouds - these take some beating: http://www.wired.com/science/planetearth/magazine/17-10/st_clouds SteveBaker (talk) 02:58, 12 October 2009 (UTC)

Pepsi One's one calorie

Does Pepsi One really have a calorie, and if so, where does it come from? PCHS-NJROTC ^(Messages) 16:02, 10 October 2009 (UTC)

I'm inclined to agree with the answer given here: [3] - the sucralose (sugar substitute) has food energy, but so little is added to the drink that the final product has only about one or two food calories in it. 66.178.144.193 (talk) 16:20, 10 October 2009 (UTC)

"One calorie" is what we officially call, in the scientific community, a bullshit marketing term. The method of measuring caloric content in foods is not precise to the single calorie; it is actually rounded to the nearest 10 calories. Thus, any food with less than 5 calories will report as 0 calories on the nutrition label. "Just one calorie" was first used as such a marketing term for Diet Coke and I believe that Tic tac mints used to advertise themselves as "1 1/2 calorie" an even more rediculous claim given how bullshit claiming even 1 calorie is. It sounds more striking than "Zero calories", which lots of OTHER brands make the claim to, so claiming "One calorie" or "1 1/2 calories" is just a catchy way of being memorable. Certainly more memorable than "We have anywhere from zero to 5 calories, but we can't tell to that precision" --Jayron32 19:56, 10 October 2009 (UTC)

Do tell us more, Jayron. Exactly why does the scientific community have such problems measuring the caloric content in foods that they are unable to provide figures less rounded than to the nearest 10? Sounds most odd. --Tagishsimon (talk) 20:05, 10 October 2009 (UTC)

Anyone could measure the caloric content of such foods empirically, and get a number which is much more accurate than to the nearest ten calories. Its just that, that's not how food calories are measured. Doing a simple experiment like bomb calorimetry tends to overestimate the number of calories in unpredicatble ways, since there's lots of stuff which burns, but which the human body cannot use for energy (like cellulose, for example). Rather, the caloric content is calculated by counting up the grams of fat, protein, and digestable carbohydrate in the food, and multiplying those numbers by standards (9 cal/gram for fat, 4 cal/gram for carbs and protein) and adding the results. Recognizing that this method is also flawed, the resulting number from that calculation is always reported to the nearest 10 calories on U.S. food labels, so officially reported caloric values are never anything but a multiple of 10 calories. You could experimentally determine caloric content to a more accurate and precise result, except that the food industry doesn't do it that way. See Food energy for a description of most of what I explain above. --Jayron32 20:19, 10 October 2009 (UTC)

That's what I was thinking; the calories on the "Nutrition Information" box seen in the US is determined by algebric equation considering the fat, sugar, and protein in a product, but Pepsi One apparently has none of these. However, the Nutrition Information box on Pepsi One reports the "one calorie," and I thought that information was required to be scientific based on government specifications. Of course we all know that the government almost never does anything as they say they will. 71.54.231.5 (talk) 20:52, 10 October 2009 (UTC)

I'm curious, what does it actually say on the nutritional information (rather than the marketing)? In the UK, amounts smaller than can be reliably distinguished from zero at the standard precision (but aren't actually zero) are described as "trace" although that doesn't quite make sense for calories... --Tango (talk) 21:05, 10 October 2009 (UTC)

On American labeling, all caloric values are rounded to the nearest 10 calories, and all gram/mg amounts are rounded to the nearest 1 gram/mg IIRC. See Nutrition facts label. So anything less than 0.5 grams is reported as 0 grams, and anything less than 5 calories is reported as 0 calories. --Jayron32 23:51, 10 October 2009 (UTC)

The Pepsi website gives a mock label [4] with a 1 Calorie citation. Does anyone have an actual product sample to verify that? Also, are they legal requirements for Calorie labeling (e.g. the use of formulas and the nearest 10 rule) or can they company choose to fudge it for the sake of their marketing? Dragons flight (talk) 00:11, 11 October 2009 (UTC)

Doesn't it depend on how many Tic Tacs (or whatever) you estimate the calories for? For example, if you estimate the energy content for 1 million Tic Tacs based on the precise quantities of fat etc and presuming your production equipment and ingredients is reliably precise and consistent, you'd surely be able to estimate to within 1 calorie? Having said that according to our article (and from memory) they're advertised as having less then 2 calories rather then 1.5 calories in a few countries including I believe in New Zealand and Malaysia Nil Einne (talk) 06:20, 11 October 2009 (UTC)

Yes, you could, but as Jayron32 explains above, they don't. There really is nothing to gain by such precise measurements, other than marketing slogans and the marketers are happy to just makes things up, so why would anyone make the measurements? --Tango (talk) 06:25, 11 October 2009 (UTC)

But that's the thing. Are we sure they don't? Just because something is usually the case doesn't mean it is always the case. And it would likely vary from location to location. (For example, I'm far from convinced Tic Tac could get away with saying less then 2 calories if they generally had more then 2 calories in a number of countries.) Also it would seem to me there's a big difference between something like say a pie, where there's likely to be a large variance from pie to pie since it will depend on the meat etc and a Tic Tac with a fairly uniform consistent and a standard set of highly refined ingredients. Also Jayron32 hasn't explained what quantities are used. As I've said, there is surely a difference between estimating for 1 million Tic Tacs and 1000 Tic Tacs. Is it standard to estimate for 1000 kg? 10000 kg? Or does it go by volume? Is it really true that every single manufacturer uses this standard quantity? I'm not saying the figure definitely has any merit. I'm just saying I'm far from convinced the figure is complete bullshit. In fact I would say arguing the precision is always +/- 5 calories is just as likely to be a wild simplification. (Just because it's normal practice perhaps encouraged by the regulators, doesn't mean that it's the best scientific claim.) Also I didn't say anything about measurements. In fact I was talking about quantities used for estimation (via calculation methods). Nil Einne (talk) 06:55, 11 October 2009 (UTC)

They can probably say with reasonable confidence that there are less than 2 calories per tic tac averaged over an entire pack, which would be plenty to justify the marketing. They probably can't guarantee that every tic tac has less than 2 calories, since the manufacturing/QA process won't be good enough. --Tango (talk) 07:19, 11 October 2009 (UTC)

But that's an entirely different point. Jayron is saying it's nonsense since the value is between +/- 5 calories because of the unreliability of estimation methods but I'm far from convinced. If the average value is ~2 calories within a fair degree of precision (which IMHO could be +.- 0.5 calories or higher), that's the average value. The value per Tic Tac is obviously not going to be exactly 2 calories but that's a different point. And when it comes down to it, it seems unlikely it's going to be between 0 to 5 calories either, particularly for something like a Tic Tac. Also if the average value is 1 calorie (it doesn't seem to be), it seems entirely reasonable a high percentage of Tic Tacs are going to be 2 calories. (Some odd stuff like e.g. 2 Tic Tacs joined together will be significantly different although then we get into the complicated question of whether that's 1 Tic Tac or not.) Note that I was the first person to bring up manufacturing methods, variance between products and consistency etc. Jayron appears to be solely talking about the method to estimating or measuring energy content and the unreliability thereof, not about the natural variance between products. To reiterate, while I'm partially the cause of the confusion, my original point was that whether you are estimating the value by calculating the energy content or measuring it via some highly accurate method you can likely come up with a value with a greater degree of precision then +/- 5 calories per average serving. Obviously there's going to be variance between servings (and in many cases even between batches) but that's a different point since it doesn't matter whether you use a highly accurate measurement method or estimate the difference is still going to be there. (You do know the precise values for the units you tested but as you've likely destroyed these it's a somewhat moot point.) Or to put it a different way, there's a difference between measurement/estimation error and between false precision of a single unit of some product because of differing consistency between units. Nil Einne (talk) 07:39, 11 October 2009 (UTC)

(EC) I briefly glanced thorough the (joint) standards in New Zealand and Australia. [5]. Of greatest interest "The average energy content, and average or minimum or maximum quantities of nutrients and biologically active substances must be expressed in the panel to not more than three significant figures." This hints at something I've been thinking but didn't really mention. It seems to me to be somewhat silly to to suggest something complex like a pie with a large energy content (unless it's sugar or refined glucose perhaps) is +/- 5 calories the same as something with a small energy content like a Tic Tac. The precision surely depends at least a bit on the size of the value. It also says "Where the average energy content of a serving or unit quantity of the food is less than 40 kJ, that average energy content may be expressed in the panel as ‘LESS THAN 40 kJ’" which is about 10 calories. Note the "may". It doesn't say you aren't allowed to specify a more precise value if you know it. I presume if you do specify a more precise value, it needs to be backed up. (In any case, obviously saying 39kJ is in some ways more or less as bad as saying 41kJ.) Our article suggests that the value for average energy content for 100g (which is the standard used in NZ in addition to serving) is 1658kJ. Okay in NZ-A that would be 1660kJ. It appears to suggest there are about 200 Tic Tacs in 100g. So you end up with ~8.3kJ per Tic Tac which is slightly under 2 calories. Presuming the 1660kJ value is reasonably accurate it seems difficult for me to presume it's going to be that much higher, up to 5 calories. And it seems to me reasonable you can estimate the value for 100g to a greater degree of accuracy then between 0 to 4187 calories for 100g of TicTac. And as I've said, Tic Tacs are something of sufficient consistency that a value per serving is going to be reasonably accurate. What they actually say on Tic Tac labels here I don't know but I don't think that's really the question. Nil Einne (talk) 07:39, 11 October 2009 (UTC)

(outdent) I can confirm by direct inspection at the supermarket that Pepsi One in the US has a nutritional information box stating it has 1 Calorie, 0 Fat, 0 Carbohydrate, 0 Protein. Dragons flight (talk) 12:40, 11 October 2009 (UTC)

The official Food and Drug Administration website has the following Claims That Can Be Made for Conventional Foods and Dietary Supplements. "The responsibility for ensuring the validity of these claims rests with the manufacturer, FDA, or, in the case of advertising, with the Federal Trade Commission." If a vendor or manufacturer violates these standards, legal action can be pursued by either the FDA or the FTC (depending on the type of violation). As far as measurements, the Compliance Guidance Document states that the "FDA has not stated how a company should determine the nutrient content of their product for labeling purposes. Therefore, there is no prohibition from using "average" values for its product derived from data bases if a manufacturer is confident that the values obtained meet FDA's compliance criteria." Per Nutrition Labeling Guidelines, the Pepsi may be called "Calorie Free" if it contains fewer than 5 calories per "recommended amount for consumer consumption." "The caloric value of a product containing less than 5 calories may be expressed as zero or to the nearest 5 calorie increment (i.e., zero or 5 depending on the level). Foods with less than 5 calories meet the definition of "calorie free" and any differences are dietarily insignificant." (So, the FDA only enforces to the nearest 5 calories - Pepsi One falls into this category). I think it would be silly to assume that a major beverage corporation didn't perform its due diligence before making a nutritional claim in an international marketing effort - it is clearly within acceptable limits of accuracy. The FDA has mandated that labeling claims must be validated either independently (by the manufacturer) in accordance with AOAC International-approved techniques, or using standard information from the USDA database. Information on these methods is available in this book, Nutrition Labeling, available online. This question could have been easily answered with a few good references - even the official Pepsi One website states very clearly: Information reflects rounding as required by the Food & Drug Administration (21 CFR 101). This may produce occasional irregularities in some values when comparing information for different serving sizes. They state very clearly - without any ambiguity - that there is rounding error in their measurement that is within acceptable legal tolerances. They even state the applicable legislation: US Code Title 21 CFR 101 Nimur (talk) 18:48, 11 October 2009 (UTC)

Of course that's all well and good, but it doesn't actually answer the original poster's question. Assuming that it really does have approximately 1 Calorie as stated on it packaging and nutritional label, and that's not some sort of marketing ploy, then what ingredient(s) of Pepsi One are contributing materially to that one Calorie? Dragons flight (talk) 19:35, 11 October 2009 (UTC)

There's lots of stuff there which may be marginally digestable by humans. Caramel color for example is pretty much just treated sugar caramel, and Pepsi One uses caramel color, so it could rightly claim that the one calorie came from the few milligrams of caramel color in its soda. If there were really about 1 calorie, and I had to make a guess as to the makeup of that 1 calorie, I would guess most of it is caramel color. --Jayron32 06:17, 12 October 2009 (UTC)

Water

What volume of water is in biomass form above sea level, and roughly what sea level alteration would this lead to if all life was exterminated. —Preceding unsigned comment added by 129.67.39.44 (talk) 17:42, 10 October 2009 (UTC)

A very quick initial skim via Google suggests that the World's total biomass is in the region of 10^-8 of the World's total surface water mass. This suggests that 99.999999% of the World's water is not part of current biomass, so even if all terrestrial biomass water was to be returned to the oceans (which would not necessarily happen as some water would enter the atmosphere) any sea-level rise would be insignificant. I'm sure others will be eager to firm up or refute this hasty guesstimation, if only to prove me an idiot. 87.81.230.195 (talk) 19:41, 10 October 2009 (UTC)

Even the most brief thought suggests that it would make little difference to the sea level. Biomass is a very thin layer on some of the land surface. --Tagishsimon (talk) 19:45, 10 October 2009 (UTC)

On the other had, desertification and increased evaporation on interior continental areas and increased rainfall above the oceans (perhaps on the order of 1 - 5%) could have a larger effect on sea level rise. ~AH1^(TCU) 13:39, 11 October 2009 (UTC)

Thus far we have of course been discussing short-term results. Plugging your scenario into the strong version of the Gaia hypothesis suggests that, in the much longer term, the absence of life might disrupt the Hydrological cycle and in turn the facilitation of Plate tectonics by water chemically absorbed into the Lithosphere. With plate tectonics slowing down and stopping, absorbed water would no longer be volcanically recycled back into the Hydrosphere and surface water would dwindle to nothing, as has evidently happened on Mars. 87.81.230.195 (talk) 16:33, 12 October 2009 (UTC)

Fastest human BPM

What's the highest ever recorded heart rate of a human? Thanks Pineapplegirls (talk) 17:57, 10 October 2009 (UTC)

Heart rate is naturally a lot higher in babies and young children, so do you want the highest for all humans or the highest for an adult human? --Tango (talk) 18:48, 10 October 2009 (UTC)

I couldn't find a reliable source to answer this. However I would guess somewhere around 300 beats per minute in cases of Wolff-Parkinson-White syndrome. The heart cannot sustain this rate for long because the cardiac output drops off and cardiac arrest ensues. Axl ¤ [Talk] 18:50, 10 October 2009 (UTC)

According to death from laughter, a Danish audiologist's heart rate was estimated to have peaked between 250 and 500 bpm prior to death. ~AH1^(TCU) 13:37, 11 October 2009 (UTC)

Hmm, I'm getting 404 Not Found for the reference. Axl ¤ [Talk] 16:39, 11 October 2009 (UTC)

In the article on tachycardia (rapid heart rate of various kinds), the highest number mentioned is 250 BPM for the case of ventricular tachycardia. Red Act (talk) 17:21, 11 October 2009 (UTC)

I think the definition of atrial flutter includes a rate of 250-300 bpm -- perhaps a distinction between atrial vs. ventricular beat rates should be made. DRosenbach ^{(Talk | Contribs)} 02:26, 12 October 2009 (UTC)

Music levels...

Just wondering, if I were to listen to music on the go at the same volume, would something like metal still be more damaging than easy listening? If perhaps the peaks (no idea about technical terms) were sharper. Even if I do listen to music on the go, I keep a respectable volume, I am curious anyway. Thanks! —Preceding unsigned comment added by Infiniteuniverse (talk • contribs) 22:58, 10 October 2009 (UTC)

The volume is the primary factor in hearing damage, not the type of music. Remember, Beethoven went deaf and he never listened to heavy metal. Regardless of your musical taste, keep the volume down. You will appreciate it when you are much older and you don't have to blow all your money on hearing aid batteries. -- kainaw™ 01:39, 11 October 2009 (UTC)

Was Beethoven's deafness anything to do with listening to loud music? --Tango (talk) 01:48, 11 October 2009 (UTC)

According to the Ludwig van Beethoven article, the cause of his deafness is not known for certain, but seems to have been caused by disease rather than by loud music. →Baseball Bugs ^{What's up, Doc?} carrots 01:57, 11 October 2009 (UTC)

The Hearing impairment article talks about the many causes. Loudness certainly is one cause, tied in with duration. The volume of classical music tends to ebb-and-flow more than, say, heavy metal. But listening to a shrieking soprano at high volume for a long time could likely be damaging. →Baseball Bugs ^{What's up, Doc?} carrots 02:07, 11 October 2009 (UTC)

I rarely listen to music on the go, as I indeed do want to hear well later in life. I usually listen to podcasts, sometimes ones with some music, and that is when it is mostly quiet out, so I don't have to turn the volume up. I like to have the earbuds in when it is noisy and listen to nothing also, to dampen the sound slightly.Infiniteuniverse (talk) 06:02, 11 October 2009 (UTC)

Unfortunately, many popular music albums, in all genres, are engineered for maximum loudness - see Loudness war. Therefore the difference should be minimal. MaxVT (talk) 19:09, 11 October 2009 (UTC)

In addition to the average volume, there's also the issue of the dynamic range of volumes and frequencies. I'd actually think classical music would be the worst, as they will go between silence and cannons or one loud high-pitched cymbal. The "wall of sound" approach to most popular music ensures that there is never silence and noise is generated at every possibly frequency, so as not to deprive any of your neighbors' auditory nerve cells of the opportunity to enjoy your music. StuRat (talk) 15:42, 13 October 2009 (UTC)