Wikipedia:Reference desk/Archives/Science/2011 September 17

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September 17

law of microscopic reversibility and experimental enzyme kinetics

Do the kinetics data reported for this article agree with the law of microscopic reversibility? I am looking at Table 1, where two enzymes' specificities (and Vmax's and so forth) for reactions involving ethanol, acetaldehyde, NADH, NAD+, NADPH, NADP+ (and their various combinations). I'm trying to sort it out. In any case, the authors make the arguments that one enzyme (ADH2) "favoured" the reduction reaction over the oxidation reaction.

As I recall, there are several ways to make an enzyme "favour" a reaction, such as decreased substrate specificity for the product compared to specificity for the desired reactant -- but usually this requires the input of energy. This can occur, I suppose, with energy inputted by NADH/NADPH or the alcohol that would otherwise be released as heat? elle _{vécut heureuse} ^{à jamais} (be free) 06:06, 17 September 2011 (UTC)

The relevant text is "In the case of ADH1, similar Km values and kcat/Km ratios were obtained for ethanol and acetaldehyde, indicating similar activities in both the oxidation and reduction reactions. In the case of ADH2, however, a lower Km value and higher kcat/Km ratio were obtained for acetaldehyde, indicating that the enzyme activity is in favour of the reduction reaction." Now acetaldehyde is ethanol minus two H's at the end, and the NAD+/NADH + H+ or NADP+/NADPH + H+ pairs either accept or deliver those two H's.

My feeling is that the reason why this is not perfectly symmetrical is that they're looking at kinetics, not thermodynamics. The rate at which the enzyme functions when one molecule is in excess need not be the rate it functions when the other is in excess. For a different sort of example see Inward-rectifier potassium ion channel (or any other ion channel which does not actually let things in and out with equal affinity). The enzyme can't change where the thermodynamic equilibrium point is, but it can decide when and if it will help the reactants get there. Wnt (talk) 14:56, 17 September 2011 (UTC)

medical physiology

what are the tissues which are not dependent on insulin for utilization of glucose? this is my home work and i have partially enlisted the tissues/ e.g Brain. Nerves. Liver. Adrenal glands. Lens. Skeletal muscles during exercise. — Preceding unsigned comment added by 119.153.155.106 (talk) 06:29, 17 September 2011 (UTC)

All muscles will use insulin, even during exercise, won't they? 70.91.171.54 (talk) 21:28, 18 September 2011 (UTC)

Apple cider vinegar

I see this question come up all the time outside Wikipedia, so I have to ask: what is the current status of health claims about Apple cider vinegar (ACV)? Our article on the subject says that the "consumption of vinegar might reduce obesity". The article also says that consumption of ACV might "reduce bone density", although this is unsourced. What does the current medical literature say? I realize that this is somewhat controversial, so a calm answer would be appreciated. Thanks. Viriditas (talk) 10:40, 17 September 2011 (UTC)

It's a fad. Just one of thousands that have come and gone. Nothing new, nothing different. As for the Japanese study, it's just a single, non-relicated primary study. They are dime-a-dozen and generally don't have very much scientific value until they are reproduced, criticized and confirmed by other scientists. This doesn't mean I'm calling the integrity of the authors of the study into question- they almost certainly carried out the experiment and obtained the results they reported. It's just that a single primary study doesn't mean much besides that further study may be needed. Remember cold fusion? Dominus Vobisdu (talk) 11:07, 17 September 2011 (UTC)

I agree with all of that except for the fad part. This has been popular in the U.S. for at least a century, possibly longer. Based on what I've read and seen, it's probably popular with people who can't afford to see a physician or who live in rural areas. It also seems to be used by some religious communities. So it appears that ACV is used as folk medicine in the U.S. Viriditas (talk) 11:36, 17 September 2011 (UTC)

Folk medicine and fad are not mutually exclusive. Fad does not mean "recently invented or discovered", it means "recently become popular". Dominus Vobisdu (talk) 11:47, 17 September 2011 (UTC)

Re: Fad - "was or is briefly popular"

The practice dates to at least 1839 [1] "Desault and others assert that consumption is often brought on by a common practice with young people of taking vinegar to prevent obesity", [2] "'Every one knows' says Giacomini 'that when habitually taken it produces leanness from a sort of languor of the digestive process'"

I imagine that, if in order to consume your apple cider vinegar, you have lots of salads with it used as a dressing, then you probably will lose weight. StuRat (talk) 17:34, 17 September 2011 (UTC)

Actually, they make drinks out of it now.[3] Ms. Bragg has been promoting this stuff for some time now and practically every natural foods store in the U.S. carries her products. She claims that "Hippocrates, the father of medicine, treated his patients with Apple Cider Vinegar", so this is not a fad, it seems. Viriditas (talk) 22:53, 17 September 2011 (UTC)

But how does it work? I'm interested in something a little more precise than "from a sort of languor of the digestive process". HiLo48 (talk) 23:07, 17 September 2011 (UTC)

Perhaps we should look at mother of vinegar instead. Viriditas (talk) 23:18, 17 September 2011 (UTC)

Hilo48 - RTFM Apple cider vinegar

Also see [4] for a recent analysis of some claims. — Preceding unsigned comment added by 83.100.239.6 (talk) 12:26, 18 September 2011 (UTC)

14 years ago is "recent"? The most recent studies are from 2009 (see the Wikipedia article). Viriditas (talk) 13:35, 18 September 2011 (UTC)

Thanks for picking me up on that.Imgaril (talk) 16:05, 18 September 2011 (UTC)

Race

Are there inherent differences in people's traits and capacities that are entirely due to their race? — Preceding unsigned comment added by 88.83.35.117 (talk) 13:20, 17 September 2011 (UTC)

No. Collect (talk) 13:26, 17 September 2011 (UTC)

I think Swedes are better than Kenyans in converting sunlight to Vitamin A... --Stephan Schulz (talk) 13:28, 17 September 2011 (UTC)

That may be true (as a statistical average), but that doesn't make 'race' a scientific concept about which one can make meaningful assertions about 'inherent differences in people's traits and capacities' - for a start, neither 'Swedes' nor 'Kenyans' are normally seen as 'races'. 'Race' is a social construct used to divide a continuously-varying population into arbitrary discreet groups, on whatever grounds are expedient for the purpose at hand. AndyTheGrump (talk) 13:44, 17 September 2011 (UTC)

So, explain away medical differences. After correcting for income, education, urban/rural location, age, gender, etc... people who identify themselves as "black" accelerate from prehypertension to hypertension significantly faster than people who identify themselves as "white". That is just one of thousands of medical examples (just look at "racial disparity" in any collection of medical journals). One of the big hurdles in modern medicine is combating the idea that there is no such thing as race. Scientifically and statistically, there are many differences on a genetic level between the races. Accepting that there are differences doesn't imply that one race is better than another. It doesn't imply that a person has to belong to one and only one race. It simply means that people are different at a genetic level and identifying the differences and similarities allows for better medical treatment. -- kainaw™ 16:31, 17 September 2011 (UTC)

Medical differences between individuals may very well be due to 'statistical differences' at the genetic level - that has nothing to do with the demonstrable fact that 'race' is a social construct. Or if it isn't can you provide scientific evidence to the contrary? Since there is no scientific definition for 'black' or 'white', there cannot be. If you want to match medical treatments on the basis of individual genetics, you should do just that, not make assumptions based on arbitrary cultural grounds that have little relation to individuals actual genetic heritage. AndyTheGrump (talk) 16:41, 17 September 2011 (UTC)

"Race" from a medical standpoint is "genetic testing by logical deduction." Of course actual genetic testing would be more accurate, but that would imply we know which genes are responsible or even how the mechanism works. Sure, it's a social construct, but it can be used to make helpful assumptions, which is particularly important in medical care since doctors are still mostly flailing in the dark when it comes to finding appropriate care for the specific patient in front of them. Sure, it's imperfect, but that doesn't mean it's worthless or should be dismissed out of hand. SDY (talk) 16:47, 17 September 2011 (UTC)

It is based on a politically-motivated argument that skin color and genetics have absolutely nothing to do with one another. I do not buy into that argument at all. I believe that a person's skin color is based on the person's genetics. I really don't care how "racist" that makes me. I refuse to force myself to be stupid. -- kainaw™ 16:50, 17 September 2011 (UTC)

I don't think you understand. Obviously skin colour is decided by genes. The problem with the concept of race is that it is arbitrary to separate the human species into 'races' based on this one particular genetic variability among humans. For example, there's also a genetic basis for the determination of blood group, and people of different blood groups have other medical differences (ie different susceptibility to certain diseases, like cholera), but no one would propose that we divide people into races based on blood type. 65.92.5.209 (talk) 17:04, 17 September 2011 (UTC)

Unfortunately, they do. Not really a "race" but in some parts of the world assumptions are made about your personality based on your blood type. There are also some weird diets that try to use this too. Mainstream science states that both of these attempts to link blood type to other traits are baseless, but that doesn't stop people from trying. SDY (talk) 17:13, 17 September 2011 (UTC)

It was just an attempt to claim that since "black" and "white" don't refer to blood type, they shouldn't refer to skin color. I disagree. -- kainaw™ 17:16, 17 September 2011 (UTC)

One could make the same argument about gender. That is, it's a continuum, rather than black and white, with intersex individuals in the middle. Does this mean that recommended breast exams for women and prostate exams for men should be eliminated because "gender is just a social construct" ? Of course not. Since most people identify as either male or female, having different medical guidelines for them makes sense, just as it does for people who identify as black or white. StuRat (talk) 17:19, 17 September 2011 (UTC)

I don't think the argument is about medical treatment. Obviously it is desirable to take genetics into consideration as much as possible when prescribing medical treatment, and if people with genes coding for darker skin are more likely to have genes influencing hypertension or whatever, doctors would be ill-advised to ignore it. But that says nothing about whether race makes sense as a scientific concept. Undoubtedly our awareness of the (relatively) few genetic differences between blacks and whites is because they've been studied so scrutinously, as they should be (for medical reasons). But hopefully in the future an individual's genome could be cheaply sequenced so as to allow much more individualized treatment. Where would the concept of race be then? 65.92.5.209 (talk) 18:05, 17 September 2011 (UTC)

It will be right there on the surface of the skin. Increased genetic data will not change the color of my skin and I seriously doubt it will change yours either. -- kainaw™ 18:16, 17 September 2011 (UTC)

Exactly. 65.92.5.209 (talk) 18:28, 17 September 2011 (UTC)

African and European populations were traditionally regarded as the two most different human races merely because of the striking differences in skin color. In contrast African pygmies and Melanesians are so phenotypically similar that they were classified as a single race. But the truth is rather different - Europeans and Africans are actually closer to each other genetically than to all other geographic populations. And African pygmies and Melanesians are the farthest from each other genetically. How useful is it then to call which black and which white?

Skin color in humans were the result of far stronger selection pressures depending on how close the population was to the equator, resulting very quickly in vast differences between melanin expression in different populations, even among close geographic neighbors. Just because a person is darker than you doesn't mean your genes are more genetically distinct from each other than to a person of a more similar shade. See this to get an idea of just how awkward it really is to arbitrarily split those into neat little chunks. And that's not even accurate nor complete, as genes among populations flow, ebb, well up, dry up, double back, spread out, and most importantly - merge (Central Asian hordes in Eastern Europe, early Southeast Asian sailors in Madagascar, European invasion of the Americas, the Slave Trade).

But I agree, phenotypic differences can be useful in quick determinations of which genetic population you might belong to and which diseases you are more susceptible to. But ascertaining geographic ancestry is a better indicator. Why then should we stick to a very inaccurate, very vague means of indicating possible genetic variation by the color of the skin when we can just do it far more efficiently and with little additional effort by merely saying 'West African', 'Native American', 'Central Asian', 'West European'? Even better if you can pinpoint the specific population - Yoruba, Iroquois, Pashtun, Basque. The same principle of genetic clustering applies, but with a more solid basis than just phenotype. After all, doctors don't exactly check your medical history and diagnose your disease by putting you next to a skin color wheel.-- Obsidi♠n Soul 19:42, 17 September 2011 (UTC)

Many people don't know their full ethnic background, but pretty much everybody knows their race. StuRat (talk) 06:36, 18 September 2011 (UTC)

Maybe in the USA. In Australia in my lifetime quite a number of people have discovered that they have some Australian Aboriginal ancestry. If any human grouping is ever going to be classified as a race, that would be one of the first. HiLo48 (talk) 07:23, 18 September 2011 (UTC)

There are lots of people in the USA who are mixed-race, some of them so mixed that their ethnicity is no longer clear-cut. 67.169.177.176 (talk) 00:54, 20 September 2011 (UTC)

There are two sides to this question. The first is, What do we mean by "race"? Once we've got that to a good situation, we can answer the main question.

Biologically, race has no particular scientific meaning. What this means is that there aren't just a handful of basic, discrete categories of human beings that are then "mixed" up. The human species isn't actually made of five primary "colors" (white, black, red, yellow, brown) like anthropologists in the 19th century used to believe. Genetic studies in particular have shown that all humans on all continents are heavily interrelated, and that genetically it is a totally smooth set of transitions between regions. The reason it looks like a few basic "colors" is because there are a few places in the world that, because of historical and geographical circumstances, managed to develop large, relatively homogenous looking populations. So we see the world as looking like white/Western Europe, yellow/China and Japan, black/Sub-Saharan Africa, red/North American plains, etc. This is an artifact of history, not biology.

Furthermore, we can't actually tell what "race" someone is genetically. There is no gene for "race". What there are are genes that are probabilistically indicative of having ancestors from one part of the world or another. So we can look at your genes and say, "hey, you have gene A15B (or whatever), and 80% of the other people who have that gene had ancestors in the last 10,000 years that came from Western Europe." That's as close as we get to having genetic tests for "race".

That doesn't mean that "race" doesn't have meaning as a social category (where its meaning is quite important and profound, and shapes people's lives). It doesn't even mean that it has zero meaning as a scientific category, if understood as a probabilistic statement about one's possible genetic ancestors. But it's not a firm category.

So. Probabilistically speaking, do people whose genetic ancestors hail from different parts of the world have inherent differences in traits and capabilities? The answer is, probabilistically, yes. Here's a canonical example for thinking about this: 1/3rd of all people whose ancestors are from Sub-Saharan Africa have a gene that makes them slightly more resistant to malaria. (This is the ultimate reason for Sickle-cell disease, which is when you get two recessives of that gene in the same person.) This is what I would call an inherent difference in traits and capabilities. It's also only probabilistic — you can't tell from looking at a token "black" person on the street whether they have this particular gene. It's not something that all people of that race have. And it's not something that's necessarily exclusive to that race (something similar exists in Mediterranean peoples as well — see Thalassemia.) It's a genetic difference that is real, has real effects on "capabilities and traits," but again, all things related to race as probabilistic, and only tell you about changes over populations, not individuals. These are ways to talk about differences between groups, not differences between people.

Note as well that "race" isn't often the most useful category for talking about origins. Fast twitch muscle fibers are probabilistically more common in people descended from East Africa than other groups. Is "black" the right category for talking about this mutation, or "East Africa", or something more specific?

We should not be surprised that there are differences between groups on the aggregate. We also should not exaggerate what they mean, nor confuse such differences as being the explanations for expressed results, which are filtered through many different layers of social context. Every group will have more or less similar variation on most qualities — there will be some people who are absolutely awful at some things, and absolutely brilliant at others, and as with all things genetics, a huge proportion, sometimes the majority proportion depending on the circumstances, has to do with the environment in which the individual develops as well. --Mr.98 (talk) 13:48, 17 September 2011 (UTC)

Theory aside, though, there are groups of traits that are found together on a reasonably common basis enough that "race" is a meaningful big picture concept. It's actually sort of relevant in blood banking, because certain red cell antigens are more or less only found in certain ethnic groups. This causes problems, since sickle cell anemia, primarily found in people of African descent, sometimes requires transfusions, and African-Americans as a group are not very well represented in the donor population. If you have a sickle cell patient with antibodies to the U antigen, testing a bunch of white people is extremely unlikely to find a compatible donor. While the color of the skin has nothing to do with it, and these genotypes/phenotypes may not be linked in the sense of being close on the same chromosome, you're still more likely to find a compatible donor among dark-skinned individuals, though even there that particular phenotype is pretty rare. SDY (talk) 16:23, 17 September 2011 (UTC)

There is no need for a "theory aside" with regards to my comment. If you read what I wrote you'll see what you're saying is completely compatible. I did not say that race was purely a social construct, nor that it had absolutely no biological use. It just doesn't mean what most people colloquially think it does, and its best seen as a fuzzy, probabilistic category regarding human populations, rather than individuals. --Mr.98 (talk) 21:26, 17 September 2011 (UTC)

I totally agree. I was just providing a very specific example of the practical utility of it. SDY (talk) 22:34, 17 September 2011 (UTC)

I'd just like to say, although I am not the OP, Mr. 98's is an awesome answer and he should feel good. 86.164.76.231 (talk) 22:21, 17 September 2011 (UTC)

Yes, great work 98! The worst aspect of this discussion is that 98% of it is about skin colour. (Sorry about that figure. They say 98% of statistics are made up on the spot, and that number appealed to me at the time.) If race is useful at all, we need to use it in a slightly more sophisticated way than just looking at someone's skin colour. A dark skinned Australian with Aboriginal background is not going to be closely related to the average dark skinned American. HiLo48 (talk) 22:58, 17 September 2011 (UTC)

That race equals skin color is an American thing. There's a lot of very unpleasant history that plays into it. SDY (talk) 23:24, 17 September 2011 (UTC)

Not exclusively -- in fact, racism based on skin color goes back to Biblical times at least (Genesis 9:25, "Cursed be Canaan..." and so on), and in fact the African slave trade began first with the Arabs and then the Portuguese, with the English and the Americans getting on the bandwagon quite a while later. 67.169.177.176 (talk) 03:45, 18 September 2011 (UTC)

We have a nice article on historical race concepts. There are many different ways in which ideas about race have emerged and changed over time. The American model is important — both for its domestic effects, and its many export effects — but hasn't been the only important one. Today there are a lot of vernacular race concepts floating about. --Mr.98 (talk) 22:39, 19 September 2011 (UTC)

I think that earwax and alcohol flush reaction show some differences, not to mention sunburn and I suppose rickets - but as always these are differences between individuals who happen most often to be of certain races, which do not apply to every last person of each race. Wnt (talk) 15:00, 18 September 2011 (UTC)

It is an American tendency to judge the qualities of a human by their ethnicity. The plague of racism will halt the growth of nations amongst their meaningless bickering, and we will never reach the level of a Type 1 civilisation if we continue this ancient battle. →Στc. 05:31, 19 September 2011 (UTC)

Who exactly do you mean by "we"? It's not like everyone belongs to the same civilization, y'know! 67.169.177.176 (talk) 00:49, 20 September 2011 (UTC)

No, that tendency is universal, not uniquely American. StuRat (talk) 05:36, 19 September 2011 (UTC)

The focusing in on the idea of "race" is something that is particularly strong in the United States, given its history as an immigrant nation. But I do agree that people seem to have a universal tendency to find arbitrary reasons to hate other people who are in some what slightly different than they are. --Mr.98 (talk) 22:39, 19 September 2011 (UTC)

Really? What about racism in Europe? What about the discrimination against Australian abos, just because they belong to a different race? I could go on and on with this... 67.169.177.176 (talk) 00:52, 20 September 2011 (UTC)

I'm not a racist, I drive the speed limit! :-D 67.169.177.176 (talk) 05:03, 20 September 2011 (UTC)

vancomycin

I was a registered nurse for 19 years and I was reading the article regarding vancomycin which was posted on Wikipedia and it referred to it as a 'drug of last resort'. I've found this is not true. Often times when a patient was admitted to my floor, the doctors would prescribe it before the results of any blood cultures and sensitivities were ever submitted. Yes, after the blood cultures or sputum samples were collected, the doctors would either change the orders to some other antibiotic or keep the patient on vancomycin, so therefore, I disagree it is a 'drug of last resort.' Thank you, Lee Hollimon. — Preceding unsigned comment added by Owen7252 (talk • contribs) 13:36, 17 September 2011 (UTC)

I know I've seen the same complaint in print, and if I find it I'll add it... meanwhile though, I should point out that even in 2002 vancomycin was starting to see resistance with drugs like linezolid and quinupristin/dalfopristin vying for "last resort" status against Staphylococcus aureus.^[5] It also is facing some new competition from an engineered mutant.[6] Still, I see a lot of articles to this day calling it a drug of last resort, even though it is part of the initial regimen recommended by the CDC for patients with suspected bacterial meningitis.[7] Wnt (talk) 14:23, 17 September 2011 (UTC)

It could be worded better to place the claim in better context. With bacterial meningitis, the progress of the infection is so rapid that a doctor would not wast time on trying something else to see if it worked. For some other infections it is held in reserve in case all else fails. It is the treating physician call at the out set, as to which antibiotic is best for his patent and balance the risk of possibly inducing resistance at the same time.--Aspro (talk) 17:12, 17 September 2011 (UTC)

SPICE and opamps

Since Bob Widlar made the first integrated circuits at Fairchild before SPICE was available, how did he know they would work properly. Or did he use some other sort of simulation program?--78.148.142.217 (talk) 17:31, 17 September 2011 (UTC)

Widlar made an integrated circuit op amp. Op amps were designed and built with discrete components long before that. SPICE was released in 1973. On-chip transistors were demonstrated at Texas Instruments in 1958. The notion that integrated circuits could not be designed until a computer simulation program became available is ridiculous. Where do you think the experience needed to write SPICE came from? Cuddlyable3 (talk) 23:26, 17 September 2011 (UTC)

Like all computer programs, electronic CAD simply accelerates a computation that a programmer already knew how to do. In particular for SPICE, the actual work it does is well-known, but very boring - repetitive calculations of linear and nonlinear equation networks. The circuit models are based on physics - equations some human derived to quantitatively model observed properties of semiconductors. (Take a look at your SPICE model for one transistor element - see some familiar looking parameters like dopant concentration and transconductance? Those got typed in by a human, and they're nothing but inputs into one of your favorite transistor current equations!) SPICE also iterates over parameter sweeps and can perform numerical optimization ("relaxation" or "simulated annealing" to be more precise, for most of the SPICE work you probably do on a daily basis). This technique allows the program to solve network equations for large numbers of coupled active and passive circuit elements. You can solve them by hand, too - it just gets boring after two or three iterations! Nimur (talk) 14:49, 18 September 2011 (UTC)

Binary sun

What would a binary star look like from the surface of a planet orbiting them? Would the motion of the two stars around each other be visible? Would the two stars even be visibly separate, or would they look like one blob? --75.33.217.234 (talk) 17:59, 17 September 2011 (UTC)

It depends entirely on the planet's orbit and the stars' orbit around one another. For example, the planet recently mentioned by NASA has an entirely different orbit time than the stars' orbit. So, every day, the sunrise of each star and sunset for each star will be different. They may be in sync. One may be long before the other. There will be times when they eclipse one another. There will be times that they are far apart. -- kainaw™ 18:03, 17 September 2011 (UTC)

I suppose you could even have the case where the planet is located at the barycenter between the two stars, so that they appear to rotate about it, always in opposition to one another, so you'd have a planet with no night, ever. I don't think that position would be stable over the long term, though. StuRat (talk) 19:10, 17 September 2011 (UTC)

normal-sized camera?

This discussion has been closed. Please do not modify it.
The following discussion has been closed. Please do not modify it.
Having red about red-shift, it seems since there is no color shift in this picture, it means that the camera was not shrunk along with the person. Does this make sense? How could the person take the photo, it would seem like the weight of the camera would utterly crush him. 82.234.207.120 (talk) 18:40, 17 September 2011 (UTC) srsly? --Daniel 19:00, 17 September 2011 (UTC) on 82.234.207.120 (talk) 19:34, 17 September 2011 (UTC) First, there is no redshift in this situation. Redshift is a change of frequency. If you throw tennis balls at a wall, they come back to you at the same rate that you threw them, regardless of the shape of the wall. Likewise light and the spoon. If you throw tennis balls at a wall while backing away from the wall, the later tennis balls will take longer to get back to you. That's an example of frequency shift from relative motion. But there is no relative motion in this case. Second, the only thing you can really see, and the only thing cameras detect, is light. If the light is distorted by bouncing off of a curved surface, that doesn't mean the person or camera that emitted the light is distorted. It just means that your brain is playing tricks on you, incorrectly interpreting the light. -- BenRG (talk) 19:15, 17 September 2011 (UTC) you're saying that the camera could have been shrunk without distorting the picture? What about the fact that only 1/10th (or whatever) as many photons are hitting its receptors? I just find it hard to believe that that is not a full-sized camera, based on the picture quality. Can you address this please. 82.234.207.120 (talk) 19:37, 17 September 2011 (UTC) Hmm, it looks to me as if the spoon was magnified rather than the photographer shrunken. But that would be too strange, so obviously it must just be something funny about perspective. Redshift theory for shrunken objects is rather involved. We would need to know which shrinking method was used here: Desiccation shrinking (i.e. just removing the water), atomic shrinking (i.e. the atoms get smaller) or decimation shrinking (i.e. removing a certain percentage of atoms). But we are not allowed to give medical advice anyway. If you need advice with a redshift problem you should really see your shrink. Hans Adler 19:43, 17 September 2011 (UTC) practically speaking what is the technology in e.g. 'honey I shrunk the kids'? It's 2011 I assume this is what is in use, but it could also be a trick, that's why I'm enlisting the reference desk help for forensic photography references hopefully concerning actual science and not just conjecture. 82.234.207.120 (talk) 19:57, 17 September 2011 (UTC) This is getting uncomfortably close to medical advice, and I'm afraid I have already said too much. If you are experiencing redshift phenomena or other shrinking symptoms you absolutely must see a doctor rather than asking random people on the internet for advice. Don't play with your life! Hans Adler 20:14, 17 September 2011 (UTC) Your concern touches me so much that I am fapping. But I do not see any kind of redshift -- or any other artifact, that's the point. My conclusion is, since it is such a preeminently normal photo, without artifacts of any sort (except the oversized spoon) we can only conclude that the camera is normal-sized. Actually, someone might suggest that instead of the person being shrunk, the spoon was embiggened. Is there a way to tell from the photo, as this would cause a considerable shift in, um, focal length or something? (depth of field? focus? f-stop? I'm seriously out of my league here, I don't know anything about lenses or photography). Can someone who know the science behind photography analyze the photo for me and give me a definitive verdict, with justification, one way or another? This thing is, like some hypothetical remote control for prosthetic testicular implants, driving me nuts. 82.234.207.120 (talk) 21:40, 17 September 2011 (UTC) After a detailed analysis, I propose it to be a novelty oversized spoon Jebus989✰ 21:56, 17 September 2011 (UTC) That is a very funny and clever interpretation, but the spoon seems too "perfect" for me to be a novelty item, it doesn't seem like something hand-made at that scale, but machine-stamped at the normal spoon scale. Look at high shiny it is as opposed to these pictures. But back to the scientific method, do you have any forensic evidence from the photography itself? Maybe based on the reflections, or something you can tell from the pixels? 82.234.207.120 (talk) 22:02, 17 September 2011 (UTC) also look at the scratch in the spoon toward 6 o'clock. the spoon is relatively new/freshly pressed and has no other scratches. if it were a novelty oversized spoon, it would have a lot of little scratches all over, not big gashes like that. (Because of the scale of the things that would scratch it). A normal-sized spoon, on the other hand, could easily be scratched in a couple of characteristic scratches like that. It just seems to me to be a normal-sized spoon, magnified: in other words, if the picture was really taken, then it seems to me that it was the man that must have been shrunk. Occam's razer. 82.234.207.120 (talk) 22:11, 17 September 2011 (UTC) Photoshop. I do not see the reflection of the arm in the bowl of the spoon. Collect (talk) 21:46, 17 September 2011 (UTC) That reflection is interesting. If someone here could model mathematically the apparent curve of the spoon and use photoshop to dereflect around that plane couldn't we get a clear image of what the spoon is reflecting? We might actually be able to tell the relative dimensions of the person as compared with the rest of whatever is behind him or her that presumably hadn't been shrunk. 82.234.207.120 (talk) 22:05, 17 September 2011 (UTC) I think that Collect may be misled by the fact that the reflection in the spoon is inverted - this is usual beyond a certain distance from a concave reflector. I think the only odd thing in the picture is an abnormally-large spoon. AndyTheGrump (talk) 22:10, 17 September 2011 (UTC) Right. So how do you explain it? 82.234.207.120 (talk) 22:11, 17 September 2011 (UTC) How do I explain an abnormally-large spoon? Someone decided to make it. It is hardly cutting edge technology. AndyTheGrump (talk) 22:14, 17 September 2011 (UTC) Was that last bit a cutlery reference? If so I have no idea what importance whether it's a knife, fork, or spoon has to do with anything. Scientifically, there is certainly a given prior probability that an oversized spoon was manufactured; likewise, there is a prior probability that the human in the picture is a little person of such fantastically miniature proportions that this is how large they are in relation to a spoon; finally, there is a certainl chance that a spoon which was manufactured at normal size was embigenned, and a certain chance that a person grown to normal size was miniaturized. the question obviously is one of 1) the state of science, so that we can establish prior probability 2) forensic analysis as I've proposed above. This is the scientific method. Is manufacturing an oversized spoon within the realm of human technology? What about embigenning an existing spoon? shrinking a person? These are questions that need to be established for a good prior probability, but we are not Sophists here, we can look at actual facts and do real analysis, and not just philosophize. That is what I would like out of the picture. 82.234.207.120 (talk) 22:28, 17 September 2011 (UTC) Note that while we are being silly, a strong argument against it being a regular sized spoon and a small sized person is that the shopping card, floor boards, and racks of food are all "normal" sized. So it would require the shrinking of the entire supermarket setting, except for a spoon. This seems to be a priori less likely than it being just an oversized spoon. (Aside from the very obvious facts that the technology currently exists to create larger-than-usual spoons, but so far as anyone knows, does not exist for shrinking or enlarging objects arbitrarily.) --Mr.98 (talk) 22:47, 17 September 2011 (UTC) can you elaborate on the technology not existing? what was the technology in honey I shrunk the kids, and has it never been perfected? forgive me I'm not up on these things, is it like "fission" (just hard, and you can't have one in your home) or like "fusion" (just theoretically possible but no actual plants) or like "cold fusion", i.e. a pipe dream? what is this technology even called, as I can't seem to find it. Finally, I agree that other things in the picture seem "normal-sized" but I'm not convinced perspective doesn't achieve this. Couldn't you take a picture of a penny so that it's enlarged, while having everything else look "normal-sized?" Here the person would be like the penny... 82.234.207.120 (talk) 22:59, 17 September 2011 (UTC) From a very quick estimate someone 5 cm tall with 70 kg mass would have a density of over 2 million kg / m^3 (probably an underestimate) which from our article is more dense then the core of the sun. Considering all else you've said, I find it hard to believe you didn't appreciate this and can only conclude you are trolling again. Nil Einne (talk) 23:07, 17 September 2011 (UTC) It seems fairly obvious that someone who could come up with all the above would know there are plenty of reasons (like the extreme density) why a human can't be shrunk like in Honey I Shrunk The Kids. Combined with the fact this user has admitted trolling multiple times before [8] [9] I am closing this discussion and while I won't edit war if someone reverts, I strongly suggest this be left be. Nil Einne (talk) 23:07, 17 September 2011 (UTC)

Arctic survival

Suppose a modern jetliner crashes on the Arctic ice pack, but a few of the passengers and crew survive the crash. What's the LONGEST time they could reasonably survive on the ice pack? (Assume that some of them, but not all, are trained in Arctic survival techniques.) 67.169.177.176 (talk) 20:01, 17 September 2011 (UTC)

That would depend on several factors. If they have something to burn, then pretty long, since they can heat themselves and obtain water. Otherwise, you have to hypothesize how long they will be without water, at what temperature they will be, how much food they would have... Wikiweek (talk) 21:12, 17 September 2011 (UTC)

Assume that the plane's fuel tanks are not ruptured and still contain some fuel, and that the food at their disposal includes that in the plane's galley (I know, that's not much) and the emergency rations stowed on the plane (if any). Had they been without water, it would have been impossible for them to survive for more than a week or so -- even I know that much. And the whole point is to prolong their survival as much as reasonably possible -- makes for a better plot this way.67.169.177.176 (talk) 21:50, 17 September 2011 (UTC)

Also, there's a supply of potable water on board the plane -- how could anyone forget that? 67.169.177.176 (talk) 22:03, 17 September 2011 (UTC)

Theoretically infinite. The Inuit have lived north of the Arctic circle for at the very least centuries, most likely a lot longer. It would be unlikely that plane crash survivors would have the skills or knowledge to pull it off. It sort of depends where in the Arctic they are, as well, since they'd have to be near animal life to live as the Inuit did. The lack of dogs would be a problem, but not a theoretically insurmountable one. SDY (talk) 22:06, 17 September 2011 (UTC)

On the ice pack somewhere in the Beaufort Sea (the plane in question is a nonstop Aeroflot flight from Moscow to Seattle). Anyway I'm not trying to have them live there for the rest of their lives (IMHO that would be a fairly anticlimactic ending), but I'd prefer to have them survive for at least a few weeks, maybe several months if possible, before being dramatically rescued while near death from hunger and exposure. 67.169.177.176 (talk) 22:18, 17 September 2011 (UTC)

Yeah, theoretically infinite. Assume that the plane was full of Inuits and in the cargo there were lots of Husky Siberians and protein rich food, not to forget the winter jackets, boots and other tools. Wikiweek (talk) 22:14, 17 September 2011 (UTC)

That's not my plan for them (see above). 67.169.177.176 (talk) 22:18, 17 September 2011 (UTC)

This reminds me of Alistair MacLean's novel Night Without End, in which a plane crashes on the Greenland icecap -- except in that book the survivors are helped out by the members of a nearby research station. Anyway, MacLean knew quite a bit about Arctic survival, so the book might be interesting to you -- if you could find it. He also wrote a much better-known book called Ice Station Zebra, about hijinks at a research station located on the floating ice. Looie496 (talk) 22:33, 17 September 2011 (UTC)

Thanks for the tip, I'll be sure to look for it. Unfortunately the article says all his books are out of print (same as with Arthur Haley)... 67.169.177.176 (talk) 22:48, 17 September 2011 (UTC)

You mention that "a few of the passengers survive the crash". The rest of the passengers now represent a food source.

Also consider using solar methods for melting drinking water. It may be possible to use the skin of the aircraft to make a reflector that could focus sunlight onto dark colored water bottles. (Depending on the season, you might get nearly 24 hours of usable sunlight per day.)

The book (and film) Alive, would be of interest, of course. APL (talk) 23:28, 17 September 2011 (UTC)

Yes, solar methods could be used to melt water and/or start fires for doing so; however, I don't think it's reasonable that dark-colored water bottles would be found on board (although it may be possible to darken one by holding it over a smoky fire), and I also doubt that the aircraft skin would make a good enough reflector for this purpose. Perhaps one of the passengers might possess some kind of optical lens to focus sunlight? As for cannibalism, THIS WILL BE RESTRICTED TO VILLAINS ONLY -- I will NOT have my good guys eating other humans. And as for Alive, it's already on my reading/watching list for another writing project that has to do with an avalanche rescue, so I'll be sure to watch it before starting on this one (which will be at least a couple years in the future). 67.169.177.176 (talk) 03:20, 18 September 2011 (UTC)

Not that it matters to me, and not that I want to tell you how to do your job , but in my entirely unprofessional opinion, having "Bad" people survive via cannibalism, but "good" people refuse on moral grounds and still somehow make it, seems really cartoonish and hacky. Unless that's what you're going for you'd might do well to either ignore the issue entirely, or to take a more nuanced approach.

Anyway, you're very likely to find a magnifying lens. Fresnel reading magnifiers are very good for starting fires, but a pair of reading glasses with also work with a little effort. However, the amount of burnable fuel will be very limited, although I suppose your characters could burn jet fuel in a bucket, I think that would last for a while. As for dark colored bottles, beer bottles might be dark enough to absorb some energy. There might be some sports bottles in luggage, or some other sort of jug in the galley. Or if worst comes to worst you can take any sort of soda bottle and a black Sharpie. APL (talk) 06:33, 18 September 2011 (UTC)

Thanks for the advice. Yeah, I think beer bottles might work. As for the cannibalism, I think I'll pass up on that, but I will have at least one murder on racist grounds (the survivors will be a mixture of Russians and Americans, some of whom are suspicious of one another, and when you put them in such a life-threatening situation, the hostility can really escalate). 67.169.177.176 (talk) 07:07, 18 September 2011 (UTC)

If they are on the Arctic ocean they won't survive very long. Even if they have the aviation fuel they still need something to burn. There isn't a lot of food on an aircraft and they probably forgot the ice auger so fish are out. If someone brought a gun they might get lucky and be able to shoot a passing polar bear or a seal if they were near to a seal hole. And don't have them crash in July - September. CambridgeBayWeather (talk) 12:46, 18 September 2011 (UTC)

Just thought of a few more. If they are burning stuff on the sea ice it will need to be on a large piece of the aircraft or it will melt through. Also burning things on relatively flat sea ice will provide a great beacon for the search and rescue operation. They will probably be found within a few hours. You would be better to have the aircraft off course, then the rescue mission is in the wrong area, and come down on the land. The survivors could then find an old abandoned Hudson's Bay Company or North West Company post with some buildings still standing that would provide shelter. Being on land they would also have access to more wildlife, Arctic hare, caribou, muskox. etc, giving them a better chance at survival. By the way there may be no sea ice in October either and even in November the weight of the aircraft might be more than the ice can support. For December/January and possibly longer depending on how far north they are there won't be any sun to melt the ice with. Finally don't forget that if they are on newer sea ice they won't be able to drink the melt water anyway. CambridgeBayWeather (talk) 13:26, 18 September 2011 (UTC)

Or an abandoned DEW Line station, which opens up lots of mysterious possibilities. Franamax (talk) 20:35, 18 September 2011 (UTC)

If they do shoot a polar bear, make sure they don't eat its liver (unless it helps the plot, of course). AndrewWTaylor (talk) 14:09, 18 September 2011 (UTC)

I would think it unlikely for there to be firearms on a Russia to US flight. Not only is it problematic for someone to transport a firearm and the ammunition for it, but firearms are extremely more tightly regulated in Russia then in the US, so unless you have some kind of crazy special exceptions, giving the passengers a firearm would be tough to logically justify, especially one with enough umph to take out a polar bear. Googlemeister (talk) 13:54, 19 September 2011 (UTC)

If they have both the aviation fuel and an igniter, then they could simply light a fire on the ice to melt a hole, and kill two birds with one stone. They now have a fish hole and lots of fresh water (plus the means to make more...) Whoop whoop pull up ^{Bitching Betty | Averted crashes} 18:55, 18 September 2011 (UTC)

Don't forget they are on an ice pack over the Arctic Ocean, so the water and ice contain too much salt to drink. Only snow fallen on top of the ice would provide fresh water. StuRat (talk) 20:30, 18 September 2011 (UTC)

The salt is forced out as the water freezes. Why do you think icebergs are fresh water? (And I seem to recall that fish contain water...) Whoop whoop pull up ^{Bitching Betty | Averted crashes} 01:47, 19 September 2011 (UTC)

But not right away. I've never seen sea ice used for tea making until the spring. Also you woud have to melt through 2 m (6 ft 7 in) or more ice cover. CambridgeBayWeather (talk) 06:48, 19 September 2011 (UTC)

Icebergs are formed when glaciers calve at the seacoast. Glaciers are formed from snow falling inland. Snow is 2/3 steps further along the hydrological cycle than the seawater it came from. Sea ice formation has only one phase transition and it doesn't involve a vapour phase, so there will be much less segregation of different molecules. Icebergs aren't fresh water 'cause the salt was forced out, the salt never evaporated in the first place, so it wasn't in the snow. Franamax (talk) 09:35, 19 September 2011 (UTC)

Antarctic sea ice is fresh water (that's why the crew of the Endurance didn't die of thirst,) why should Arctic sea ice be fundamentally different? Whoop whoop pull up ^{Bitching Betty | Averted crashes} 22:11, 20 September 2011 (UTC)

Antarctica is a big island/small continent, and some ice slides off of glaciers formed on land by snowfall. That's fresh ice. There's also "pack ice", formed from frozen salt-water, which is all you have in the Arctic Sea (except right near the north slopes of North America, Europe and Asia). StuRat (talk) 23:16, 21 September 2011 (UTC)

But when the water freezes, the salt segregates out. 67.169.177.176 (talk) 01:17, 22 September 2011 (UTC)

The movie Island in the Sky (1953 film), viewable online for a fee from Amazon and other sources, [10] starring John Wayne, had a military plane make a forced landing on a frozen lake, and the crew survived in extreme cold , (-40 degrees) for an extended time. It was based on a true story found in the book Fate Is the Hunter. In the true incident there were 22 or so men with inadequate food marooned in uncharted frozen wilderness. An excerpt about the incident is at [11]. It had some silliness about wood not burning when it's cold. They were always about to freeze despite building a log hut which looked pretty snug, having aviation fuel available, and having lots of trees around for fuel as well as tools for cutting it. Edison (talk) 20:10, 18 September 2011 (UTC)

'Silliness'? Wood doesn't burn if it's too cold. To have a fire, you need a gas to burn, and to be at a high enough temperature that the fuel burns spontaneously. Very cold wood, that's a problem. It's like when a candle is too cold, so the wax won't properly melt and evaporate. Or when a gas burner goes out whenever the spark stops, because it hasn't got warm enough yet to sustain the reaction. 86.164.76.231 (talk) 22:27, 18 September 2011 (UTC)

I think it would be more accurate to say that it won't "ignite" at a very low temperature. But, once started, I would expect it could sustain combustion, provided the heat generated by the burning could be mostly kept in the wood, say with an impromptu furnace. And I suspect that soaking the wood in jet fuel would overcome any reluctance to ignite, just like lighter fluid does with charcoal. StuRat (talk) 05:33, 19 September 2011 (UTC)

In my experience, you would think wrong. Just because something is warm enough to ignite, doesn't mean it is warm enough to sustain the exothermic chain reaction. A very common, simple example is a gas burner on a cold day: have you never experienced that? It will ignite, but you have to continue delivering the ignition spark until the whole thing has warmed up enough, or it goes right out again. The jet fuel would almost certainly help, although isn't it usually pretty long-chain stuff? It won't be like lighter fluid, but more viscous and less flammable. You would, as you say, need a furnace or oven of some kind to keep the heat in, to sustain a fire when it's very cold. So, not silliness :) 86.164.76.231 (talk) 11:07, 20 September 2011 (UTC)

The condition of the fuselage would be critical. If it was intact and could be sealed, it would offer considerable protection from the cold and wind. If it was painted black or a dark color, then it would warm up a fair amount in 24-hour sunlight. For added drama, you could have them crash in spring, and need to be rescued before the ice pack breaks up, with suitable cracks in the ice forming and shifting of the fuselage (with associated groaning sounds) to terrify the passengers more. StuRat (talk) 20:30, 18 September 2011 (UTC)

Thanks for all the suggestions, everyone. So, can they hold out for a few weeks (under the best possible conditions, but on the ice pack)?67.169.177.176 (talk) 21:53, 18 September 2011 (UTC)

They could probably hold out for months but not on the ice pack. They would either die or be rescued quickly. Another thing I thought about is that if one of them was knowledgeable in Arctic survival then crashing near an abandoned trading post, which will have lasted longer in the Arctic than in hotter climes, will possibly give them access to tools and metal to make tools. Things like an ice chisel for making holes in the lakes for fish or a kakivak for fishing when the ice melts. They could probably find wire for rabbit snares and traps for foxes. The foxes aren't much good for eating but the fur would be useful for covering the feet, which will be one of their biggest problems, and for any women in the party. They would also be able to make spears so they could hunt caribou or get run over by muskox. CambridgeBayWeather (talk) 06:48, 19 September 2011 (UTC)

Just FYI, the story is partly inspired by the wreck of the icebreaker Cheliuskin and the subsequent disappearance of (and search for) Sigizmund Levanevsky, so I don't think I'd want the crash to happen near an abandoned trading post or DEW line station. I don't want to make things too easy for the victims (heh, heh)... 67.169.177.176 (talk) 01:00, 20 September 2011 (UTC)

Sleep paralysis without Hallucination

Sorry, but we have a policy of not giving out medical advice, because we're random people on the Internet, we don't know your specific case, and we don't want to give you false hope or needlessly worry you.--el Aprel (^facta-_facienda) 22:48, 17 September 2011 (UTC)

(ec)Wikipedia has an article about Sleep paralysis. Any answer to the OP's question which would be a medical diagnosis and against the Ref. Desk rules. Cuddlyable3 (talk) 22:52, 17 September 2011 (UTC)

SAWFISH ROSTROM ( Bill)

I have just learned of your website and am excited to get information. And plan on joining. I was born in Florida and my husband moved to Miami 40 + years ago When his mother passed he inherited many incredible things a very large green sea turtle shell, and a large in perfect condition sawfish rostrom . I found several online a small for $1500 and large for $5500 but that was dated 2009. I would like to locate a collector or museum how do you suggest I do that ?

thank you very much ! 108.65.106.2 (talk) 22:49, 17 September 2011 (UTC)

If you are really looking for a buyer then try eBay. Cuddlyable3 (talk) 22:56, 17 September 2011 (UTC)

If you want to donate them to a museum, call your local natural history museum, and see if they are interested. StuRat (talk) 03:03, 18 September 2011 (UTC)