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October 25

Is that true that the brain has arteries only without veins?

I've heard that the brain is exception of our body because unlike all our organ which have arteries and veins, the brain doesn't have veins but arteries only. If it's true, what is the way of the of the body or of the heart to draw the deoxygenated blood from the brain? 93.126.88.30 (talk) 02:38, 25 October 2016 (UTC)

Cerebral circulation describes the arteries AND veins of the brain. So wherever you heard that the brain does not have veins appears to be wrong. Vespine (talk) 02:51, 25 October 2016 (UTC)

There is one place in your body with an artery where there would "normally" be a vein, but that's the glomerulus, in the kidney. Maybe you heard something about the cerebrospinal fluid and misinterpreted it? There are the dural venous sinuses, which are veins, but a bit different from your "average" vein. --47.138.165.200 (talk) 03:19, 25 October 2016 (UTC)

=Thank you. I asked the professor who told it and he explained me that they are sinuses rather than veins, they function as veins but they are sinuses. 93.126.88.30 (talk) 18:55, 25 October 2016 (UTC)

Your professor might be referring to Dural venous sinuses? But there ARE other veins in the brain which are just regular old veins: Internal cerebral veins, Superior_cerebral_veins, Great cerebral vein.Vespine (talk) 21:54, 26 October 2016 (UTC)

Why are evolutionary the testis are located outside of the body?

Why are evolutionary the testis are located outside of the body? Here is in such way they are exposed to the damages due to their sensitiveness. Is there any assumption or speculation about this question? 93.126.88.30 (talk) 02:44, 25 October 2016 (UTC)

Our testes article even has a section called evolution > external testes. Vespine (talk) 02:49, 25 October 2016 (UTC)

One theory they didn't list is that they are "advertising fertility", much as breasts on female humans do. StuRat (talk) 15:37, 25 October 2016 (UTC)

SemanticMantis (talk) 16:09, 25 October 2016 (UTC)

For the assertion that it's not listed?? —Tamfang (talk) 01:57, 26 October 2016 (UTC)

I am pretty sure the citation is needed for the "testicles as fertility ad" bit. Hofhof (talk) 02:00, 26 October 2016 (UTC)

Yes, that is what I meant. I want a citation that tells me more about that claim, and who may have made it. As it stands now with no reference, we just have yet another zany idea proposed by StuRat. SemanticMantis (talk) 15:41, 26 October 2016 (UTC)

The only claim I made is that our article doesn't list that. StuRat (talk) 16:23, 26 October 2016 (UTC)

I have not heard this theory before. Do you have references please? DrChrissy ^(talk) 16:30, 26 October 2016 (UTC)

Thank you for asking politely. Start here: [1]. StuRat (talk) 17:48, 26 October 2016 (UTC)

Thanks for that. It is an interesting collection of alternative theories for internal and external testes. One point I would like to make is that it does not exactly say that external testicles advertise fertility. It describes external testes in terms of being a sexual attractant. DrChrissy ^(talk) 18:22, 26 October 2016 (UTC)

Good, thanks. I assume that now you understand that you did make a claim above, and that this reference supports it? Now you have traced the theory that you mentioned to a hypothesis originating in 1950's and having almost no contemporary supporters ("This theory is not widely accepted because such conspicuous displays are rare (many scrotums are barely visible) and bright coloration seems to have evolved long after the original scrotum"). That's great!

It's ok to talk about hypotheses that are not well supported, but when doing so in the future, please include a reference. SemanticMantis (talk) 20:50, 26 October 2016 (UTC)

I did not claim the theory was correct. StuRat (talk) 22:03, 26 October 2016 (UTC)

StuRat, I think you are being disingenuous here. Not only did you not provide a reference initially, but you actually misrepresented the source you were following. I spent 15 minutes looking for a mainstream article supporting your contention on Google scholar and I could not find a single one. Your posting has cost me time unneccessarily and I consider that to be disruptive. Please provide RS for your answers in the future. DrChrissy ^(talk) 22:50, 26 October 2016 (UTC)

I'm not understanding your differentiation between "sexual attraction" and "advertising fertility". The main purpose of sexual attraction is reproduction, so obviously apparent fertility is a critical aspect of sexual attraction. StuRat (talk) 23:02, 26 October 2016 (UTC)

Fertility is the natural capability to produce offspring. However, it is only one part of an animal's fitness. Fitness (biology), is an individual's ability to propagate its genes, and so is the ultimate criterion on which females select males. Some animals advertise their fitness using an intervening variable such as dominance. For example, dominant male mandrills have bluer backsides than more subordinate individuals. This more intense blue is a sexual attractant, but to the best of my knowledge, has not been linked to fertility per se. DrChrissy ^(talk) 23:33, 26 October 2016 (UTC)

You posted a theory. Whose theory is it? Where can I read more about it? This is a reference desk. SemanticMantis (talk) 17:19, 26 October 2016 (UTC)

Why do elephants and hyraxes have internal testes?

Does anyone know about the evolutionary history which has led to elephants and hyraxes (our Testicle article also lists monotremes, armadillos, sloths and the rhinoceros) being the only land mammals to have internal testes? If they are able to produce viable sperm internally, why has this not evolved in other land mammals? DrChrissy ^(talk) 16:35, 26 October 2016 (UTC)

Here [2] is a review article on the evolution of external testes from a phylogenetic perspective. It has tons of good refs, and may have some passing discussion on "why" in various groups. There is a classic tradeoff between seed size and seed number in plants, mentioned briefly at Seed_predation. I'm not as familiar with how that might apply to mammals, but here is an article on sperm size vs. sperm number [3], which may fold in to the pro/con lists for internal/external testes. I strongly suspect you'll have a hard time getting a hold of it, but this article would probably get to the heart of your question:

“ Hanks, J. "Comparative aspects of reproduction in the male hyrax and elephant." Reproduction and evolution: proceedings of the fourth symposium on comparative biology of reproduction (JH Calaby and CH Tyndale-Biscoe, eds.). Australian Academy of Science, Canberra. 1977. ”

If anyone finds a pdf, please let me know! (n.b. I restored your question after you removed it because 1. I had already typed this up 2. it is interesting 3. some of this may be useful to future searchers, hope you don't mind) SemanticMantis (talk) 17:19, 26 October 2016 (UTC)

Thanks for that information. No problems at all in reverting my deletion. The Testicle article offers several theories, but they all have their own problems. My own problem is that there is such a wide range of land animals with internal testes. So, any theory related to size or rate of heat loss seems to be problematic. Their behavioural ecology is also highly varied (e.g. compare the elephant compared to the sloth), so it's unlikely to be ecological constraints. DrChrissy ^(talk) 17:36, 26 October 2016 (UTC)

I have found this[4] rather interesting article which states "Furthermore, genera within mammalian families often exhibit variations in testicular position.10-12 Six mammalian orders contain species with internal testes and species with external testes (Marsupialia: kangaroo, etc.; Chiroptera: bats; Rodentia: rats, mice, porcupines, prairie dog, chinchilla, etc.; Carnivora; Perissodactyla (odd-toed ungulates): horses, rhinos, etc.; and Artiodactyla (even-toed ungulates): pigs, hippos, camels, deer, cows, etc.)". This really only adds to my confusion as I would have expected such an adaptation to be conserved at the level of order (just my speculation). The article then goes on to explain that some of these mammals have other thermoregulatory adaptations to keep internal testes cool "Thus, many ascrotal taxa like seals and Catacea have developed specific mechanisms for cooling their testis (e.g. venous plexuses carrying cool blood to the spermatic arteries), whereas others such as Monotremata need no such mechanisms due to their low core body temperatures." But, (there is always a "but" it seems) "The Hyracoidea and Proboscidea represent an exception as they lack a specific internal thermoregulation mechanism". DrChrissy ^(talk) 17:58, 26 October 2016 (UTC)

Quora, despite not being an WP:RS, suggests that there's an advantage in having internal testicles because they are protected from mechanical injuries, etc. But because "Some of the proteins in sperm don't fold properly at human body temperature", they became external to cool down. Btw, some rhino species also have internal testicles. Brandmeister^talk 19:52, 26 October 2016 (UTC)

• @DrChrissy: barring cryptorchidism, ungelded male horses normally have external testicles, and cows never have testicles. μηδείς (talk) 01:19, 27 October 2016 (UTC)

  • 

    An Ongole bull- the scrotum and testes are clearly external

  • Ermm...you are correct. "Cows" do not have testicles because they are female Bos taurus; male Bos taurus are called "bulls" which do have external testes. DrChrissy ^(talk) 15:36, 27 October 2016 (UTC)

Drugs

Are there any psychoactive, hormonal or psychiatric drugs that cause neither tolerance, dependence, withdrawal, paradoxical effects, severe side effects, drug effects happening long after use (like LSD) nor a rebound where whatever the drug was fighting comes back stronger than before after the effect wears off? Or do they all have one of those or another, i.e. steroids, LSD (flashbacks), and antidepressants (erection dysfunction)? Ignoring non-physical dependence unless many users get it since anything can cause that. Like a drug with no effect besides "increase persistence of vision to 2 seconds" probably wouldn't make most people psychologically addicted so would qualify. 173.46.76.152 (talk) 04:12, 25 October 2016 (UTC)

Nitrous oxide. Vespine (talk) 04:39, 25 October 2016 (UTC)

Hmm... Recreational_use_of_nitrous_oxide#Health_concerns is an unsourced passage, but I did remember a documentary-fiction on Victorian GB mentioning similar effects. Arguably those are not "severe side effects" and dependence is psychological, though.

Oh, and although the request is probably legitimate curiosity, it looks no different to the polite version of "what can I get high on?". Tigraan^{Click here to contact me} 08:57, 25 October 2016 (UTC)

I don't think it's really our business whether the OP wants to get high or not. It's legitimate to ask what euphoric substances have other enumerated effects. What people do with that information is their own lookout. We should certainly be careful not to claim that any particular substance does not have bad effects, unless we are very very certain of that indeed and can back it up. --Trovatore (talk) 09:10, 25 October 2016 (UTC)

In that exact case, I tend to agree that is not our business, but that is my own opinion. If a random IP asked which drug store products work best to dissolve a human body, I hope many would feel uncomfortable answering; similarly, some knowledgeable people might refuse to answer a question about drug use if there is a practical intent behind it. Nothing to do with the medical disclaimer. Tigraan^{Click here to contact me} 15:58, 25 October 2016 (UTC)

Fair enough. --Trovatore (talk) 23:52, 27 October 2016 (UTC)

here and here are some references to side effects of nitrous oxide. --Jayron32 11:50, 25 October 2016 (UTC)

Altering your brain waves for 3 minutes does not sound like a long term or particularly severe side effect, imho. And the webmd article is ridicolous, I don't see any good sources for the claim that severe low blood pressure or sever Methemoglobinemia are "COMMON" side effects from nitrous use. It's very widely and "incautiously" used in dentistry and during labour. Nitrous_oxide#Safety Vespine (talk) 21:46, 25 October 2016 (UTC)

Salvia divinorum may satisfy some of your criteria. SemanticMantis (talk) 14:08, 25 October 2016 (UTC)

Here and here are some sources about Salvia Divinorum. Also Salvinorin A is the active ingredient, and the Wikipedia article contains further information on its effects. --Jayron32 16:11, 25 October 2016 (UTC)

Apparently WebMD did not read or did not trust the Johnson et al. (2011) article, because they say there is "insufficient evidence" for S. divinorum "producing hallucinations", while the hallucinogenic effects are clearly reported in the latter peer-reviewed article. Its abstract concludes that S. divinorum has "a unique profile of subjective effects having similarities to classic hallucinogens, including mystical-type effects." SemanticMantis (talk) 17:04, 25 October 2016 (UTC)

I wonder what they thought the species name came from? Matt Deres (talk) 13:47, 27 October 2016 (UTC)

Oddly, our article quotes Albert Hoffman as objecting to divinorum, claiming that it means "of the ghosts". I say "oddly" because my searches for the meaning of divinus don't say anything about ghosts. They mostly say it means "divine".

So Salvia divinorum should be the sage of the divines. Our article says "diviners", but I think this is unnecessary; "divine" used as a noun already means someone who reveals that which is hidden, as in St John the Divine, a name which does not ascribe divinity to John (that would be a heresy!) but AIUI is more of a statement of his occupation. --Trovatore (talk) 02:29, 28 October 2016 (UTC)

Won't speak to unprescribed use. but Modafinil is an atypical stimulant (not euphoric as MDMA or methylamphetamine are) with few or none of the side effects of the sympathomimetic amines such as amphetamines. It's marketed as a Wakefulness promoting drug for the treatment of narcolepsy and other sleep disorders. loupgarous (talk) 04:24, 27 October 2016 (UTC)

diabetes type I and II:sugars as ?:fats as ??:salt.

Are there some analogues with diabetes, where the body is having trouble with sugar, to some problem where the body is having trouble with fats or salt? thanks144.35.45.83 (talk) 16:59, 25 October 2016 (UTC)

Salt is a major factor involved in blood pressure. Some people are more salt sensitive than others. Also, people don't necessarily know what their salt intake is because they don't closely read the ingredients of everything they eat. So, it is hard to tell exactly how salt sensitive a person might be. Measuring salt sensitivity is rather simple. A common test is to go four days with a little salt as possible. Measure blood pressure each day. Then, go four days with high salt intake. Measure blood pressure day. A 5% increase in blood pressure is often diagnosed as salt sensitivity, which is what I assume you mean as having trouble with salt.

As for fat, the pancreas (which produces insulin for sugars) produces pancreatic lipase, which breaks down fats. If the pancreas doesn't produce enough pancreatic lipase, the fats will not be broken down and they will pass through the digestive system. That commonly results in bowel issues. 209.149.113.4 (talk) 19:11, 25 October 2016 (UTC)

Separate note... Salt sensitivity (above) is a term used in medicine. You will likely find an abundance of "fat sensitivity" articles on the internet. I've never personally seen "fat sensitivity" used in the medical field. The internet articles discuss how some people are more prone to increasing fat than others. They term this to be fat sensitivity. It doesn't really indicate how a person's digestive system is sensitive to fat intake. 209.149.113.4 (talk) 19:14, 25 October 2016 (UTC)

• The "fat" analog of diabetes is hyperlipidemia. Curiously, one of the most common causes is diabetes. The "salt" analog is hypernatremia, but it is usually caused by mechanical factors rather than disease (there are a few exceptions). Looie496 (talk) 20:54, 26 October 2016 (UTC)

Hyperlipidemia is an overstatement for fats. Hyperlipidemia is an abundance of any of the lipids, not just the triglycerides (fats). A person can have high LDL and low triglycerides. There is no accepted term for "hypertriglyceremia." Therefore, a more complete (pedantic) answer would be that hyperlipidemia is a condition that includes excess fat in the blood stream. I would also shy away from claiming a cause-and-effect relationship between diabetes and hyperlipidemia. The "four pillars of poor health" are hypertension, hyperlipiedmia, diabetes, and obesity. They show up together very often, but it is difficult to claim that one creates the other. All we can be certain of is that increased caloric intake and lack of movement causes all four. 209.149.113.4 (talk) 17:33, 27 October 2016 (UTC)

Final element?

Is there a final possible element? For example, we might have 499 (atomic number 499, symbol 499), which has a known atomic weight. 108.65.83.125 (talk) 22:05, 25 October 2016 (UTC)

Also, what would the name for an element greater than 999 be? 108.65.83.125 (talk) 22:05, 25 October 2016 (UTC)

The obvious choice for element 1000 would be "Millenium". ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:47, 25 October 2016 (UTC)

You might be interested in reading about the proposed island of stability. SemanticMantis (talk) 22:36, 25 October 2016 (UTC)

ec :All isotopes of all elements beyond Uranium are unstable with half-life of less than a billion years. The general trend is: the larger the mass, the shorter the half-life; but this is not always the case. See island of stability for more details. This being said, you can think of monstrously large nuclei where gravity becomes an additional stabilizing factor. There is a mass range in which the nuclei of this size -- essentially neutron stars -- will be stable both against alpha-decay and against gravitational collapse to a black hole. Dr Dima (talk) 22:42, 25 October 2016 (UTC)

I strongly believe that the final element that will ever get an official name is element 120. Georgia guy (talk) 00:25, 26 October 2016 (UTC)

I wouldn't be quite so pessimistic. I'm willing to bet that we'll get to the superactinides within a decade, looking at previous trends. Double sharp (talk) 10:26, 26 October 2016 (UTC)

See Systematic element name which only officially goes to Element 999. Try unnilnilnilium Unnn for element 1000.[5] But this reference is not so serious as it finds element symbols for element 2882 and 5885. Graeme Bartlett (talk) 02:19, 26 October 2016 (UTC)

As to final element see [6] which said 137. But at element 173 the electric field near a nucleus should be strong enough to generate a positron electron pair, so a bare nucleus would be unstable. Graeme Bartlett (talk) 02:41, 26 October 2016 (UTC)

Other references [7] which is readable here: https://arxiv.org/abs/1207.5946. Graeme Bartlett (talk) 02:54, 26 October 2016 (UTC)

The Extended_periodic_table article is worth a read, especially the End of the periodic table section of it. That article hints that element 172 or 173 might be the last element. LongHairedFop (talk) 09:53, 26 October 2016 (UTC)

This editor has been trolling the extended-periodic-table articles for some time now. The final possible element under current theories is 173. Double sharp (talk) 10:23, 26 October 2016 (UTC)

A proposed name for the "last element" is feynmanium, but last time I read these articles there was an understandable degree of uncertainty and disagreement. I mean, speculating on what happens in nuclei you've never seen before surely takes a lot of balls (I mean, 173 white ones for the protons and even more black ones for the neutrons. :) ) Wnt (talk) 19:51, 27 October 2016 (UTC)

There was a real dispute some years ago, but now there does not seem to be much doubt that the limit is somewhere around 170. (That's why the article looks a lot surer now! ^_-☆) Double sharp (talk) 06:48, 28 October 2016 (UTC)

@Double sharp: I just looked at it again and it doesn't sound surer to me. It talks about a hypothetical calculation that shows that relativistic effects influence how the 1s orbital works ... somehow. Then it talks about a Bohr model that obviously is not real. Then it briefly mentions some Dirac equation I admittedly don't understand, and cites [8] which is from 2012 that ends by saying elements over 173 may be possible. So far I'm relatively convinced that 173Ust¹⁷³⁺ might not be possible, but as for the rest, I don't know. Wnt (talk) 19:08, 28 October 2016 (UTC)

Indelicato (which I added) is very clear about this: "the most likely 'end' of the periodic table [occurs] when the 1s electron binding energy dives below −2mc²." However, we also do not yet "understand what would an atom do when the 1s shell has dived into the negative energy continuum." Doubtless the results would not support keeping the atom that way, since this is so widely considered an "end" (only Greiner among experts disputes that). (Which is actually an interesting stopping point because 172 is expected to be the next noble gas completing the eighth period.) Double sharp (talk) 01:54, 29 October 2016 (UTC)

Kow (1972) suggested element 243 would be the last hypothetical periodic table element and that it be called zunzenium (Zz) after a Chinese idiom: "The name stands behind Zun Zen, who came last on the list of successful candidates in a royal examination." Karol (2002) suggested the previously mentioned neutron star element would have an atomic number on the order of 10²¹ and that the heaviest of these could perhaps be called zettium after the zetta- SI prefix for 10²¹, while his preference would be godzillium. Sandbh (talk) 01:28, 28 October 2016 (UTC)

I like the first name, even though I think I've once said (IRL, not here) that one of the first signs of senility or crankiness in a chemist is the urge to reformulate the periodic system. I'm not sure I can buy neutron stars as elements. Where is their electron cloud, that would give them a chemistry? Double sharp (talk) 06:48, 28 October 2016 (UTC)

Well, yes, quite so. Karol says, "Neutron stars exist. They have traces of protons and electrons and are stable toward beta decay and to breakup by fission. Neutron stars have been around for a long time, arguably representing our heaviest elements…already in nature." He concludes by saying, "Regarding how far the [periodic] table might be extended, the question of nuclear stability for larger and larger systems and the role of fission, which predict an end to stability and ordinary chemical expectations, was discussed from a purposely simplified perspective. Eventually the role of gravity grows in significance, leading to the viability of astronomically large stable nuclei, [italics added] already present in nature as neutron stars." I gather he was engaging in a bit of academic whimsey. Sandbh (talk) 09:24, 28 October 2016 (UTC)

I must confess that the more I read this paper the less inclined I am to trust it without 10²¹ moles of highly radioactive salt. He suggests continuing the spdf-style blocks even though the chemistries of those elements are unlikely to follow suit (Z = 168 is almost certainly not a noble gas, but a post-transition metal similar to lead). He also completely neglects shell effects in the superheavy elements that create barriers against spontaneous fission, so that we actually do have hopes of going somewhat beyond Z = 125 and seeing the mythical second island of stability around Z = 164. (Admittedly he says that in a footnote, but would it have hurt so much to put it in the main text, especially since it would have helped his point about a neverending periodic system?) Though it seems that the n:p⁺:e⁻ ratio in neutron stars is usually around 10:1:1, these electrons are not exactly available for chemistry and so I would not really consider these chemical elements. In any case, neutron stars are not really single elements: near the crust you can actually find discrete Fe nuclei. (As well, who wants to have a disconnected periodic table?) His citations range from the reliable to the laughable (e.g. C-X. Jiang, really? That guy is still confirming my statement about crankiness on viXra with his periodic table model.) Double sharp (talk) 11:06, 28 October 2016 (UTC)

I see what you mean about C-X. Jiang; one article in Physics Letters A which appears to have then been cited (exclusively) by Jiang eight times in various preprint server papers, none of which appear to have made it into journals. As for Karol, his abstract seems to anticipate your observations:

"Since the mid-18th century, a new element has been discovered on the average of every two-and-a-half years. Hypothetically extending the periodic table beyond its current seventh row is discussed from several perspectives. For heavier elements, relativistic effects confound anticipated electron configurations. Nevertheless, it is suggested that the shell-partitioned display format (spdf) following Mendeleev and Seaborg be continued. Second, the tendency of higher atomic number elements to not survive long enough to be meaningful is addressed with the liquid drop model, including simplified discussions of binding energy and fissionability that for simplicity's sake neglect shell effects. The model provocatively suggests that astronomically large "nuclei" would be stable."

"Provocative" indeed. I see Karol is described as a retired nuclear chemist who chaired the Joint Working Party for the Discovery of New Elements since its inception in 1999 and that this JWP approved elements 113, 115, 117 and 118 for inclusion in the periodic table. Sandbh (talk) 03:16, 29 October 2016 (UTC)

The thing is, though, these simplifying assumptions might be useful in the lower reaches in the periodic table, but in the areas he is speculating about they are emphatically not helping his case. I do like his graph on the average element-discovery time, though whether his predictions are applicable now: after three elements in 1994 and 1996, we've had three in 2004, one in 2006, another two in 2010, and nothing since then. So, we've been stuck at completing the seventh period with E115 and E117 for over six years now. Then again, we had an even longer gap between Hs and Ds of ten years, so we can wait a bit longer for the beginning of the eighth row. Nevertheless, Karol's credentials are impeccable and I am quite all right with overlooking the article's flaws, appealing to its nature as a little diversion. Double sharp (talk) 04:58, 29 October 2016 (UTC)

October 26

Alien signals

So could there be a grain of truth in all the fuss facebook is full of these days about NASA having detected alien signals? --Eleven oh seven (talk) 01:28, 26 October 2016 (UTC)

No, it's just noise, but the tabloids love to report that aliens sent us a distress signal. And they are also quite bad at correcting past news which turned out to be wrong.

For analysis, see [9] or [10]. Hofhof (talk) 01:58, 26 October 2016 (UTC)

an article here is HD 164595. Graeme Bartlett (talk) 02:00, 26 October 2016 (UTC)

Facebook is about as reliable as a guy shouting stuff on the street corner. Considering NASA's budget cuts, "we found aliens, give us money" would be all over their website if it was true. These sorts of fusses start when someone misrepresents a legit news story like this or this (which are about SETI, not NASA, checking on a signal Russian astronomers found last year and dropped the ball in asking someone to confirm. The original story was "SETI si looking at a signal that could've been a defunct satellite or planetary disturbance or mixed signal but aren't sure." Tabloid reporters then misrepresented (i.e. lied) that story to make it sound more like "scientists maybe found aliens," after which crazy bloggers further distorted to fit conspiracy theories (see Circular reasoning). Then someone on Facebook shared that or a similar blog post, a friend of theirs just copied-and-pasted the title but not the link as a new post, another friend paraphrased that post, and so on until you get people posting "we found aliens" on Facebook. Ian.thomson (talk) 02:09, 26 October 2016 (UTC)

Can humans train to sleep less?

In the same way that we can train to run longer and farther, or lift heavier weights, could humans also train to sleep less?Hofhof (talk) 01:53, 26 October 2016 (UTC)

Nope, you need about eight hours of sleep per twenty-four hour period. It is a built in function, though there's some debate on how badly breaking up those eight hours throughout the day can be. Either a solid eight hours or biphasic (say, a two hour nap and six hours later; or two four-hour blocks during the night) are almost universally accepted as reasonable; while trying to go with something like a half-hour nap every six hours is generally regarded as crazy. Ian.thomson (talk) 02:20, 26 October 2016 (UTC)

But what makes it non-trainable? Why won't the body adapt to less possibility of sleep? Wouldn't sleep be more intense, if you are really in the need of it? Hofhof (talk) 02:30, 26 October 2016 (UTC)

It's a basic human need. It would be like training to do with less water. In short, self-defeating. ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:36, 26 October 2016 (UTC)

We can be trained to do with less food. The body would adapt to this situation and reduce our size.Hofhof (talk) 02:40, 26 October 2016 (UTC)

For extreme consequences of not sleeping, read Fatal familial insomnia. ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:45, 26 October 2016 (UTC)

Starvation isn't training to do with less food. If you continually get less food than you need, you die, period. Inedia is regarded as lethal quackery by pretty much everyone who doesn't practice it.

If it's short of starvation, then it's not training, it's dieting. Even that can cause trouble. Ian.thomson (talk) 03:23, 26 October 2016 (UTC)

For more extreme consequences of not sleeping, refer to Donald Trump[11] (and Margaret Thatcher[12]). Thincat (talk) 09:50, 26 October 2016 (UTC)

The question is clearly a reasonable one: In fact, one of the major problems with weight-loss diets is thsat when you eat less, the body conserves calories - which means that you need less food. While this can only be done to a limited degree, the point is that it can be done - and the question is if sleep can also be trained in that way. עוד מישהו Od Mishehu 10:04, 26 October 2016 (UTC)

The analogy to eating is somewhat apt. For a fixed amount of activity, a heavier person uses somewhat more energy. As a result, if you vary your total food intake by a little bit, then your body will tend to gain or lose a little bit of weight and stabilize. That is probably what you had in mind by an "adaptation", right? A change in the body to adjust to the changed conditions without requiring other changes in lifestyle. Of course if you decrease food intake too far, the body can't adjust on its own. You'll start to starve. Up to a point, one can also compensate for loss of food by reducing activity. Someone faced with a substantial food shortage can "adapt", up to a point, by a combination of losing weight and reducing activity. That's an adaptation too, though it comes with negative consequences to lifestyle. Persistent moderate reductions in sleep (say 6 hours a night) is a little like the person who is forced to adjust to food shortages by curtailing their activities. The body and mind may suffer and function less effectively, and your lifestyle is likely affected, but you can maintain that state for a long time if you have to. Are you "adapted" to less sleep? Perhaps, but it may come at a cost of reduced quality of life. As far as I know there is no way to train your body and mind to function at the same capacity level with reduced sleep. There is no analogy to a sleep muscle that you can develop, for example. The body has a certain amount of mental and biochemical work it needs to do when you sleep. If you prevent your body from accomplishing that then your body won't function at optimum capacity. Depending on needs, that may be okay or even necessary for a while, but I wouldn't recommend operating on reduced sleep for extended periods if you can avoid it. Dragons flight (talk) 22:40, 26 October 2016 (UTC)

There are also mechanisms that will favor using less efficient but more energy efficient ways of recuperation if you don't push your body very hard (your body becomes lazy). This allows the body to be able to deal with harsher conditions without paying any price in performance provided there is enough energy available. A bit less sleep time simply means that the body will expend more energy/nutrients to do the same repair jobs in less time. You need to cross some threshold before you'll see your performance deteriorating, at some point the body will not be able to ramp up the processes needed to do the job. For some people this limit may be 6 hours sleep, but it's know that there are people who do fine on just 4 or even 3 hours sleep a day. And by "fine" it's not that they function barely within acceptable limits, suggesting that 8 hours sleep would benefit them a lot. Take e.g. Stanley A. McChrystal, the article says: "McChrystal is reported to run 7 to 8 miles (11 to 13 km) daily, eat one meal per day, and sleep four hours a night." Count Iblis (talk) 01:30, 27 October 2016 (UTC)

While the amount of actual sleep doesn't change much, people who exercise regularly tend to require less time in bed. The fall asleep faster, stay asleep longer, and wake up faster. In a paper I wrote a few years ago, I referenced articles all the way back to 1966 (Baekeland and Lasky) that found a strong correlation between effective sleep and exercise. 209.149.113.4 (talk) 14:03, 26 October 2016 (UTC)

Yes, there are different stages of sleep, and for some stages we could get by with less, while others are critical. So, if you can change your sleep patterns, possibly less would be sufficient. The question might come up as to why we even have "shallow sleep" stages, if "deep sleep" is better. Well, you can wake up more quickly from shallow sleep, so in some situations this is the only safe way to sleep. Also, before artificial light, in winter there were many more hours of darkness than we needed for deep sleep, so filling in the rest with shallow sleep makes sense (cats are masters of this, but, in their case, during daylight). StuRat (talk) 14:18, 26 October 2016 (UTC)

Have a read of Circadian rhythm sleep disorder. DrChrissy ^(talk) 15:10, 26 October 2016 (UTC)

Why does a bear sleep in winter? Because he had a hard summer and needs a rest? No. He sleeps because he cannot find much to eat anyway and while sleeping he saves energy and avoids risks. Some kind of standby. Same with humans sleeping in the night. Now you might say: "oh there have been clinical experiments with humans that did not sleep. They get ill or even can die". Humm...what happens if you delete or corrupt standby.dll in your PC? It might hang or crash. Is this a proof that standby is existantially important for the PC? No, it's not. It only means if you disturb a build-in machanism, the whole body gets out of balance. --JMS (talk) 17:17, 26 October 2016 (UTC)

Except humans are not bears. And humans are not computers. "Do humans need sleep to survive or live normal lives?" can be answered by looking to see if, on the balance, they either die or have their quality of life reduced substantially if they do not sleep. Whether or not bears sleep or computers sleep is irrelevant to answering the question. --Jayron32 17:28, 26 October 2016 (UTC)

Also, hybernation is not sleep. Bears sleep regularly in the summer. 209.149.113.4 (talk) 19:01, 26 October 2016 (UTC)

• The question was whether people can train themselves to sleep less, but several of the responses seem to be about whether people can learn to stop sleeping completely. Anybody who uses an alarm clock to wake up is sleeping less than the biological default, and many people who use alarm clocks find that they tend to wake up around the time the clock would usually go off even if they don't actually have it set. So I would say yes, to at least some degree people can train themselves to sleep less. Looie496 (talk) 20:45, 26 October 2016 (UTC)

Looks like we have trained our bodies to need more sleep, see here:

"Members of three hunter-gatherer societies who lack electricity—and thus evenings filled with Facebook, Candy Crush, and 200 TV channels—get an average of only 6.4 hours of shut-eye a night, scientists have found. That’s no more than many humans who lead a harried industrial lifestyle, and less than the seven to nine hours recommended for most adults by the National Sleep Foundation."

"Though the San, Tsimane, and Hadza often average less than seven hours of sleep, they seem to be getting enough sleep. They seldom nap, and they don’t have trouble dozing off. The San and Tsimane languages have no word for insomnia, and when researchers tried to explain it to them, “they still don’t seem to quite understand,” Siegel says." Count Iblis (talk) 21:33, 26 October 2016 (UTC)

No, sleeping less is known to come with diabetes and depression. Influenza interferes the chronobiology. Keeping a human out of sleep is a way of torque. If somebody tells to you, people use least 10 % of brain, and sleeping too much in their lifetime, he may be interfered by the «L. Ron Hubbard Club». So do not trust! --Hans Haase (有问题吗) 12:31, 27 October 2016 (UTC)

Yes, but consider this question: How old is Donald Trump? You can look this up and find out that he is 70 years old. But he sleeps only 3 hours per night. What if he had taken your advice and had slept 8 hours per night? He might have been in better health, perhaps he would not need the statin he uses. However, consider that while every day contains 24 hours, someone who sleeps for 8 hours only has 16 hours available. Donald, on the other hand has 21 hours a day available. This means that one "Donald day" is equivalent to 21/16 = 1.31 "normal days". This means that Donald at the age of 70 years has had available the same time as a normal person has at the age of 1.31*70 years = almost 92 years. But even a huge improvement in physical fitness due to sleeping 5 hours longer per day would not have countered the effects of aging 22 years more from 70 years old to 92 years old. Count Iblis (talk) 18:18, 28 October 2016 (UTC)

The plural of anecdote is not data. The fact that humans are variable does not negate the fact that there are minimum sleep requirements for people. In other words, the minimum recommended sleep required by people in a given night is not invalidated because you found one example where a person does fine on less than that. 1 divided by the entire historical population of earth is not significant enough to bear mentioning in a discussion such as this. --Jayron32 18:25, 28 October 2016 (UTC)

I agree, but this reasoning is valid at the individual level. So, Donald's minimum could be 3 hours, and he could presumably decide to sleep (or try to sleep) a lot longer. A more typical example may be someone who gets the minimum 7 hours sleep, but who could sleep 8.5 hours. My point is then that only looking at improved health of sleeping 8.5 hours a day instead of 7 hours does not give you the full picture, because you're not taking into account the 1.5 hours lost per day. A similar calculation will show you that by sleeping 7 hours per day, by the age of 70 you'll have been awake for for the same time as someone who sleeps 8.5 hours a day at the age of 76.8 years. Count Iblis (talk) 18:39, 28 October 2016 (UTC)

Post-nasal drip

Why does post-nasal drip cause soreness in the throat? Our article mentions this but doesn't attempt to explain it, and the same was true of a lot of sources that I found through Google. Nyttend (talk) 17:39, 26 October 2016 (UTC)

I think you may be misinterpreting: post-nasal drip is a symptom that is often coincident with other symptoms, including pain, that are ultimately caused by an inflammation (rhinitis, sinusitis, and so on), frequently because of a bacterial or viral infection. One symptom does not strictly cause the other symptom. Our medical articles use terminology like pathogenesis and causal inference to help guide you toward the style of thinking that medical professionals use. The disease is the abnormal condition; the symptoms include post-nasal drip and pain or soreness; the pathenogenesis is, for example, the specific bacteria that is infesting the patient. Nimur (talk) 18:05, 26 October 2016 (UTC)

The answer is apparently, officially, "it doesn't" This paper in 2008 seems to address your exact question, with the answer (in scientific terms) "It doesn't exist as a syndrome". To wit "...medical textbooks do not mention PNDS [post nasal drip syndrom]. The term is in common use in the modern literature, but some authors report that there is no accepted definition of the condition" I.E. even the concept of the existence of the condition is not even widely accepted by medical literature. This is from 2008, so fairly recent. To piggy back on what Nimur has said, the symptom of your nose dripping back into your throat exists, but there is no evidence that that symptom causes a sore throat, though both a sore throat and post-nasal drip may be simultaneous symptoms of something else. --Jayron32 18:11, 26 October 2016 (UTC)

Then I misunderstood something; I thought "post-nasal drip" was the mere symptom of nasal mucus going down the throat, while the syndrome was a situation of disputed reality in which, allegedly, post-nasal drip happens without some sort of illness that naturally would force increased mucus production. I was merely asking about the symptom. Both personal experience and plenty of websites testify to the fact that drinking water (or basically anything else) temporarily softens the sore throat, which I'd always taken as an indication that the mucus caused the pain. Since that's not the case, why does consumption of liquids temporarily relieve the pain? Simply that the liquids temporarily wash away the pathogens (i.e. pain returns as they spread back into the throat), or that wetter throat-surface cells are less susceptible to the pain-causing effects of the pathogens, or something else? Nyttend (talk) 18:22, 26 October 2016 (UTC)

I'm afraid we cannot tell you why your sore throat goes away with any certain treatment. We can say that both heat and cold can be used to treat pain That article discusses mechanisms for each. --Jayron32 18:26, 26 October 2016 (UTC)

Pardon me, but I'm not asking for medical advice. Nyttend (talk) 18:29, 26 October 2016 (UTC)

I never said you did. I gave you a reference for mechanisms of pain relief. --Jayron32 23:26, 26 October 2016 (UTC)

If gravity on Mars is around 38% that of Earth, how rovers there stay in contact with the ground and don't float?

Thanks in advance.--93.174.25.12 (talk) 17:55, 26 October 2016 (UTC)

• Because 38% of a number that is not zero is also not zero. For example, if the rover has a weight of 100 Newtons on Earth, then it has a weight of 38 Newtons on Mars. You'll notice that 38 does not equal zero. --Jayron32 18:22, 26 October 2016 (UTC)

• There seems to be an unstated and incorrect assumption there, that any nonzero weight would keep the rover on the surface. That's not true. If you tried to put a rover on a tiny asteroid with hardly any gravity, it would be difficult to keep it from flying off into space, say from inertia when it drives over a hill. It would need to move very slowly, or have some other method to maintain contact. StuRat (talk) 19:45, 26 October 2016 (UTC)

• I've decided I like when you talk, because it confirms how smart you really are... --Jayron32 23:23, 26 October 2016 (UTC)

I have seen many balloons in the air and this was not a place with zero gravity. --JMS (talk) 18:17, 26 October 2016 (UTC)

That's because the balloon's weight is less than an equivalent weight of air that it displaces. This is due to buoyancy and not literal weightlessness. A helium balloon in a vacuum on earth will still sink to the ground. Watch this video for an explanation. Unless the rover was less dense than the surrounding air on Mars, it will not float on that air. Since the Martian atmosphere is considerably less dense than even Earth's, it seems unlikely that a 38-N weight rover would float. --Jayron32 18:22, 26 October 2016 (UTC)

Indeed - and just to clear up a bit of earlier confusion in some now-removed discussion: the weight changes when the force of gravity changes - but the mass stays the same. Objects appear to "float" when they have zero net force, which is a totally different thing than having no mass, and it's even a different condition than having zero weight. Objects float when the net force is zero, not when the weight is zero. Examples include neutral buoyancy here on Earth, which can occur in static- or dynamic- conditions like some roller-coaster rides, some instants inside an aerobatic airplane doing a maneuver; or a SCUBA diver or a biological creatures like certain types of fish, and so forth.

Although the force of gravity on the surface of Mars is lower than the force of gravity on Earth's surface, it is still a force, and it still tugs the rovers toward the planet. They "stick" there, even though their weight is lower than it would be on Earth. That "sticking" to the ground is the effect of the normal force exactly counter-balancing the weight.

As strange as it is to have to spell this out, the normal force is what keeps you from falling through the floor: it's why you can simultaneously have a weight, but also not be falling right now, because you have zero net force on your body, so you aren't accelerating downward.

Take a look at our articles on weight, and on mass, and let us know if you're still confused.

Nimur (talk) 18:27, 26 October 2016 (UTC)

The Martian atmosphere has a surface density around 0.020 kg/m³.[13] That's 60 times less than Earth's atmosphere and 50,000 times less than water so rovers ain't gonna float off. If you think of temporarily going airborn when they drive over a bump then consider that their speed is measured in metres per hour. Curiosity (rover)#Specifications says: "It can travel up to 90 metres (300 ft) per hour but average speed is about 30 metres (98 ft) per hour". 90 metres per hour is 2.5 cm per second. Exercise for the reader: How high would it reach if it suddenly travelled straight up at that speed? PrimeHunter (talk) 18:48, 26 October 2016 (UTC)

high doses of dextromethorphan leading to a false positive test for Phencyclidine

Consider a *hypothetical* patient F, an addict and a habitual user of dextromethorphan at very high plateau 4 or sigma level doses, but only consumes dextromethorphan. She often passes out on the street, gets picked up by emergency medical services, gets admitted to the emergency room in a hallucination-filled haze, and twice in the morning she has been told she has tested positive for phencyclidine, much to her amazement. (This is generally of no legal or medical consequence whatsoever, because she gets discharged the very next day.)

Out of PURE scientific curiosity, and not a request for medical or legal advice, how is it possible to get high off of a completely legal over the counter drug but test positive for an illegal category 1 controlled substance? I know DXM and PCP antagonize the same receptor, but are they literally using a close homologue of the NMDA receptor as an antibody for the drug screen?

Hypothetically, how bad would be an issue like this be grounds for issuing an FDA consumer complaint about the test? (If this is, a legal advice request letme know. I am not asking for professional advice at all.) 50.200.152.3 (talk) 18:14, 26 October 2016 (UTC)

Read This. --Jayron32 18:17, 26 October 2016 (UTC)

Look at the articles for the two drugs. Both contain a phenyl ring, and both contain a cyclohexyl ring attached to it. They also both contain a piperidine ring, but in DXM it shares two carbons with the cyclohexyl ring while in PCP it is separate. So it is conceivable that an antibody or the like might cross-react. A proper test with some sort of chromatography should not be confused; a "drug screen" etc (emphasis on the screen) could be. Of course, it may not matter to a company if they fire a few people wrongly, or fail to fire people when they say they want to; provided they get a bureaucrat's or investor's smile at the right moment, their price is paid. Wnt (talk) 00:47, 27 October 2016 (UTC)

Or, he could read the article I pointed him to... --Jayron32 02:23, 27 October 2016 (UTC)

True, but it didn't explain the structural similarities the way I'd prefer. But while we're at it let's expand the references it lists (because it really just passes through this tidbit with little elaboration):

Schier J, Diaz, JE. Avoid unfavorable consequences: Dextromethorphan can bring about false-positive phencyclidine urine drug screen. J Emerg Med. 2000;18:379–381. (one case, sounds like a very high dose)

Rogowski R, Krenzelok, E. Averting the medical, social, and legal implications of a false positive phencyclidine determination (Abstract No.167-NACCT Annual Meeting). Clin Toxicol. 1997;35:551.

Desai S, Aldea D, Daneels E, et al. Chronic addiction to dextromethorphan cough syrup: A case report. J Amer Board Fam Med. 2006;19:320–323. (one case, positive urine test in a chronic DXM addict. A bit disturbing that this was hospital "urine toxicology", given this was already known in the literature)

Wnt (talk) 19:27, 27 October 2016 (UTC)

Why does my neighbors' kitten have such a small tail?

I don't know who the father is. It's a young Tuxedo cat and as far as I know, all its relatives have regular tails, but this kitten looks like it has a large black caterpillar attached. I don't think it has ever been injured.— Vchimpanzee • talk • contributions • 20:02, 26 October 2016 (UTC)

Could it be part Manx cat ? If not, perhaps it has a spontaneous mutation, similar to the one in the Manx cat. StuRat (talk) 20:08, 26 October 2016 (UTC)

I think Manx have shorter tails. I've never taken a good look at the stray cats in the area, though.— Vchimpanzee • talk • contributions • 20:11, 26 October 2016 (UTC)

Manx cats' tail lengths are variable: could be a "stumpie" or a "longie" – read the "Appearance" section in the article StuRat linked. {The poster formerly known as 87.81.230.195} 90.211.130.104 (talk) 02:50, 27 October 2016 (UTC)

If I have an opportunity I'll provide a photo. I don't know whether my neighbors have one, and I don't have a camera or the type phone that takes photos. This question will probably be archived by that time.— Vchimpanzee • talk • contributions • 23:03, 27 October 2016 (UTC)

It's about the length of a "longie", but not as neat.— Vchimpanzee • talk • contributions •

How sure are you that the cat hasn't been injured? This sounds very much like the cat has experienced multiple breaks in his/her tail and a portion has been removed. This would give it the appearance of a large caterpillar as stated in the OP. DrChrissy ^(talk) 17:31, 28 October 2016 (UTC)

Why can't I smell a dead animal in my house?

On Friday morning I smelled what I believe to be a dead animal near what I believe is called a return for the furnace. I have smelled animals that died in the basement (not tall enough to stand up) through this vent before. I don't know how it could have died since even though I still have poison out for mice, I haven't seen or heard one that I am aware of, and my neighbors' cats now have an opening if they want to get in, so I can let them take care of mice. They used to before one opening was closed after the cats misbehaved in my basement. If a cat or cats killed something I doubt they'd leave it behind but you never know. I haven't heard anything this time to suggest what the animal was.

On Friday evening in my living room I could smell that smell again, but when I went in my bedroom which is directly off the living room, I couldn't. Later that night I could smell the animal in my room all night long, which was unpleasant. The next morning, no smell in my room but I could smell something in the living room unless I stayed in there for a long time. And coming in to the house, even the kitchen, from the outside, I could smell the animal. I can't smell anything in my room now and if I enter the living room from elsewhere, or come in the house from outside, the smell is still there.— Vchimpanzee • talk • contributions • 20:10, 26 October 2016 (UTC)

Some points:

1) Don't combine poison and cats, as the poisoned mice might be eaten by the cat, and the cat may be sickened or die.

2) Smells don't spread evenly. If you watch smoke rise from the tip of a cigarette, you will get an idea for how uneven the distribution is. It may blow one way or another, depending on the air currents at that moment.

3) Smell generation will vary with the decay state. For example, a gas bubble may build up inside, then find it's way out all at once, greatly increasing the stench at that moment. Temperature will also have a major effect.

4) In a house, smells may travel thru the walls, ceilings, and floors, past one room and into another, depending on the air currents, locations of openings, etc. StuRat (talk) 20:17, 26 October 2016 (UTC)

Regarding noticing the smell more when coming in from outside: see olfactory fatigue. SemanticMantis (talk) 20:39, 26 October 2016 (UTC)

What I would do is break this down into simple steps. First, it is quite common for perfectly healthy people to sometimes get brief episodes of [14]. As smell is the most primeval of our senses it can sometimes becomes over exited. So get a friends in (much better then a mere neighbour). Then, without giving him/her any description of the smell just ask them if they can smell something out-of-place. Without that hint, they may be too polite to volunteer a report of an unpleasant odour. Also, two-heads are better than one. They may be able to look beyond the obvious and identify the real problem, as often, a home owner can't see the wood for the trees. This seems to call for someone that you can trust to have a good look around for indications that you may have missed.--Aspro (talk) 13:39, 27 October 2016 (UTC)

I appreciate the warning about cats and poison. I never thought about it but I would assume even if the cat finds the mouse it's already dead. I wasn't getting results with traditional traps so someone suggested glue traps.

As for my getting someone else to smell my house, I'm not planning on it.— Vchimpanzee • talk • contributions • 17:56, 27 October 2016 (UTC)

Why poison mice anyway? Whole idea of a trap is recovery. Some traps are designed to be more humane if that is your preference, though they can also be useful to secure volunteers for, ehm, experiments... Wnt (talk) 19:30, 27 October 2016 (UTC)

Glue traps must be one of the most inhumane ways to kill a mouse. The mouse runs into the glue, gets stuck and then dies of dehydration/starvation. A totally unethical method of pest control IMHO. DrChrissy ^(talk) 20:54, 27 October 2016 (UTC)

The lucky ones get their little mouths/noses covered in the stuff and suffocate. The unlucky ones die by dehydration, probably. The really unlucky ones don't die before you remember to check the trap... Wnt (talk) 21:58, 27 October 2016 (UTC)

The man who sold it to me said the mouse takes the poison back to its nest. It didn't make sense since it sounds like the mouse will get stuck. I have no interest in humane or ethical. I want the dirty pest gone. Anyway, I still don't know what died or how.— Vchimpanzee • talk • contributions • 21:25, 27 October 2016 (UTC)

I am seriously questioning whether this question should be on this reference desk. We are dealing with individual circumstances of human perception, a single location and a highly idiosyncratic context. This is not science. DrChrissy ^(talk) 21:53, 27 October 2016 (UTC)

My hypothesis would be that if you poison mice in your house, you're going to get stink in hard to find places pretty reproducibly. Wnt (talk) 22:00, 27 October 2016 (UTC)

Yes, but the question is why the OP can't smell the dead animal - we do not even know it is a mouse. DrChrissy ^(talk) 22:58, 27 October 2016 (UTC)

Well, I sure smelled it last night, in the one location where I first smelled it. But I didn't smell it when I walked in the house this afternoon. It sure seems like science to me.— Vchimpanzee • talk • contributions • 23:01, 27 October 2016 (UTC)

As smell is such an important sense it may be heightened at night, even in humans. Fos in the olfactory pathways depends on the phase of the circadian clock. For Fos see c-Fos . During the day your home may be better ventilated also but after darkness when the wind drops the odours may accumulate at the same time when your sense of smell becomes more sensitive. Also, don't see why you don't what people sniffing around the house, they might just find which cupboard you have stored your Durian fruit in and forgotten about -as if thats possible ho ho.--Aspro (talk) 13:44, 28 October 2016 (UTC)

I have my reasons for not letting people in. I didn't really smell anything last night, though occasionally there was something very faint, especially around the door to my bedroom which is next to that return. Also, I have slight cold or allergy symptoms.— Vchimpanzee • talk • contributions • 16:10, 28 October 2016 (UTC)

Not really useful here, but I did smell it around the heat return last night.— Vchimpanzee • talk • contributions • 18:13, 29 October 2016 (UTC)

October 27

Does an inguinal orchiectomy result in the removal of the *entire* vas deferens?

Basically, this one person on this forum here:

http://forums.eunuch.org/showthread.php?27751-Is-it-possible-for-a-doctor-who-performs-an-orchi-to-remove-the-entire-vas-deferens

--told me that an inguinal orchiectomy results in the removal of the *entire* vas deferens.

Indeed, is this information accurately? Does an inguinal orchiectomy result in the removal of the *entire* vas deferens all of the way up to the seminal vesicle (in addition to the removal of the testicles and epididymis, obviously)?

Any thoughts on this? Futurist110 (talk) 00:44, 27 October 2016 (UTC)

Ask the surgeon who is going to perform the procedure. Beyond that, see WP:NOTAFORUM, WP:CRYSTAL, and WP:DISCLAIMER. μηδείς (talk) 01:06, 27 October 2016 (UTC)

Wikipedia has an article titled Inguinal orchiectomy which describes the procedure sufficiently to answer your question. --Jayron32 01:36, 27 October 2016 (UTC)

Given that the spermatic cord, which contains the vas deferens, has to be tied in two places, and cut between them, it is inevitable that there will be a short section left. To cut it right at the end would leave nothing to tie - which would risk internal bleeding as it also contains the blood vessels which serve the testes. Wymspen (talk) 09:19, 28 October 2016 (UTC)

As noted in Vasectomy, oftentimes one or both ends of the tubes will be cauterized. ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:08, 28 October 2016 (UTC)

October 28

Why did old TV screens dwindle to a tiny dot when switched off?

And why was this dot in the centre of the screen specifically? Equinox ◑ 13:35, 28 October 2016 (UTC)

Because the scanning coils no longer scanned. The the few electrons (cathode rays) being produced by the still hot emitter (gun), thus took a straight path to the centre of the screen.--Aspro (talk) 13:59, 28 October 2016 (UTC)

Some relevant diagrams at cathode ray tube. SemanticMantis (talk) 14:33, 28 October 2016 (UTC)

A CRT screen works by creating an electron beam pointed toward the center of the screen, which is then deflected by electromagnetics to create each dot. The electromagnets turn off right away when the TV turns off, and the residual electron stream thus hits the center. StuRat (talk) 16:24, 28 October 2016 (UTC)

Not quite instantly. The picture could be seen visibly shrinking to a dot, and the dot might wander around slightly for a bit until the scanning waveforms died out completely. By the way, the picture on CRTs was not made up of dots (I presume StuRat is implying pixels), rather, it is made up of lines and each line carries analogue information. SpinningSpark 21:45, 28 October 2016 (UTC)

I am not sure, but I think a cathode ray tube television is just an oscilloscope being fed a fancy signal. Certainly there are some elaborations like using magnetic rather than electrostatic deflection to allow a larger screen, and the colored phosphors laid out in a repeating pattern, but the basic idea seems there. Wnt (talk) 22:39, 28 October 2016 (UTC)

Not exactly "just an oscilloscope being fed a fancy signal". Based on my limited experience with oscilloscopes, my understanding is that the intensity of the electron beam in those is constant. In a CRT TV, the intensity of the beam is what's varied to produce bright or dark areas on the screen. --69.159.60.36 (talk) 10:38, 29 October 2016 (UTC)

The electrons are drawn towards the screen by the high positive charge on an anode with a hole in its center for the electrons to go through. The high voltage is generated by a voltage multiplier and without some active way of discharging it will continue to hold its charge for some time. It will discharge eventually through a high resistance but in the meantime there will be a spot on the screen as the cathode will stay warm for a while. Making a mechanism to quickly discharge the anode when the power is turned off is a non-trivial task because of the high voltage. Dmcq (talk) 23:23, 28 October 2016 (UTC)

Just as an interesting tangent to this question: while everyone knows that computers used CRTs to display text and sometimes graphics for many years, some of the earliest computers (in the late 1940s) had a completely different use for them: they were the main memory of the computer. The idea was that when the electron beam is pointed at a particular part of the glass and then turned off, it takes a while for the charge on that part of the glass to dissipate. You can then tell whether there's a charge there by pointing the beam at it again and seeing how it behaves. If there is, that's a 1-bit and you recharge the spot using the beam. If not, it's a 0-bit and you don't recharge it. A single CRT might have a 32x32 grid of positions, enabling it to store 1,024 bits, or as we would now say, 128 bytes. See Williams tube. Modern main memories are a bit larger! --69.159.60.36 (talk) 10:46, 29 October 2016 (UTC)

The OP did say 'diminish' : (intransitive) To disappear gradually. wiktionary even though this takes just a few milliseconds. It is a matter of proportionality. The scanning coils need energy to scan and one can see this if the supply voltage falls – the picture gets smaller, (30 odd years ago in Brazil one could by primitive looking electromechanical voltage regulators, to keep the TV picture the same size as the mains voltage went up and down). Same thing happens to the electron beam but instead of having to illuminate the whole screen, the residue electron only illuminate a small area. Good thing too. If all that energy required to illuminate the whole screen just hit the centre of the screen without being spread out across the whole screen, they burn away the phosphorus coating. I used to come across this sometimes when someone had tried to 'fix' a telly without out ensuring the raster circuits were working first. It left the TV with a dim spot in the centre of the screen and as the c.r.t. was the most expensive thermionic vale in the whole set, it rendered it only good for spare parts. Talking of oscilloscopes, the TV has a built in oscilloscope. It is the screen itself. By looking at (preferably) the test card transmissions one could tell what needed doing. I think it was seeing how a magnet placed upon the screen and deflect that little dot that got me interested as a kid in repairing TV in the first place – together of course with the extra pocket money it started earning me. So , the energy to keep the oscillators and raster scan going, dies pretty quickly but the hot 'gun' still emits enough electron, with at a high enough potential between cathode and anode to excite the phosphorus at the centre of the screen. Final, the CRT acted as big condenser (capacitor). This was evident even if it was removed and on the work bench if one placed one's fingers on the wrong places before discharging the charge through a high resistance and received a big belt from it. Hence, their early use as computer memory tubes. @SpinningSpark. Colour television screens have a mask behind them so to only allow one RGB picture element (PEL) to be illuminated at a time. Take a magnifier glass and look a (say) a Sony Trinitron and they are all little distinct PEL's, so me thinks StuRat is right in that context.--Aspro (talk) 12:00, 29 October 2016 (UTC)

Reasons for and severity of the dangers of leaving mobile phones on during flights

I have repeatedly been told to shut off the wireless functionality of mobile phones during flights, but do not know why. Why is it hazardous, and how hazardous is it?--Leon (talk) 15:44, 28 October 2016 (UTC)

• We have an article Mobile phones on aircraft, not a very good one but at least it leaves a trail of links to follow if you are interested. Long story short, it could interfere with various avionic systems, including communications and GPS, but there is no instance where wireless was proven to be at fault. Tigraan^{Click here to contact me} 15:49, 28 October 2016 (UTC)

• There is the danger from cell phone batteries catching fire, but that isn't removed by turning them off. Also, the in-flight entertainment system, often pushed as a "safer" and profitable replacement for passenger's own electronic devices, has been blamed for at least one incident: "The IFE system was implicated in the crash of Swissair Flight 111 in 1998". StuRat (talk) 16:36, 28 October 2016 (UTC)

Without this rule, you would have many passengers picking up their phones to call home near landing time. Now, mobile phones will increase transmission power if needed, and that's certainly likely to happen when calling from inside a plane. Then imagine 200 people switching on their phones, each phone would transmit at a power of the order of 1 watt, this RF power of all the phones collectively would cause massive interference inside the plane affecting the phone users, so they would keep their phones switched on for longer trying to get in touch with whoever they are calling. So, even if you start with a handful of phone users at any one given time, their mutual interference would cause more simultaneous phone users as the phone calls take a lot longer to be completed. You could thus easily get a total RF power of a few hundred Watts inside the plane.

A phone that is transmitting at some specific frequency that is subjected to huge levels of RF interference will start to produce intermodulation signals. To transmit a signal at some frequency, an oscillator produces a signal at the desired frequency, which is then amplified. But if you subject the device to an RF interference, then this RF signal will mix with the current that is used to amplify the signal from the oscillator, giving rise to spurious signals at different frequencies (at the sums/differences of the original frequencies). Each phone will thus end up transmitting at many different frequencies, it is then possible that the plane's communication or GPS systems will be affected. That would only require a small fraction of the total power of a few hundred watts to be converted to signals at frequencies close to those used by the plane. Count Iblis (talk) 18:01, 28 October 2016 (UTC)

Sorry, this is a pure speculation. There is no evidence that phones can produce any unusual frequencies because some other phones work nearby. The highly non-linear parametric processes, that you refer to, require such strong electromagnetic fields that phones (together with the plane) will likely melt before this parametric generation becomes significant. Please, stick to verifiable facts. Ruslik_Zero 19:27, 28 October 2016 (UTC)

Well yes there is evidence, see this paper for instance. Specifically, the research found intermodulation products from mobile phones in the DME and GPS bands, two important aviation navigation aids. Intermodulation due to transmitters receiving an interfering signal through their transmission antenna is a well known and common phenomenon amongst radio engineers. SpinningSpark 21:19, 28 October 2016 (UTC)

There's another issue besides any possible hazards to the airplane, which is possible problems with the cellular system. Depending on the altitude, a single phone might try to connect simultaneously with a large number of cell towers, and the system might not be able to handle that. --69.159.60.36 (talk) 10:50, 29 October 2016 (UTC)

Disregard the answers above. Youtube has the right one: Why can't you use phones on airplanes. Hofhof (talk) 14:06, 29 October 2016 (UTC)

Question about plane waves

On the "Plane waves" page it states that the argument of the wave equation (ω t − k ⋅ r) can be obtained by using the "scalar product" as shown below. But I'm wondering, where did the negative sign come from? Since this section references the four-vectors of special relativity, I think this assumes the use of the standard metric signature (+---) but I don't see that stated and I want to be sure. Also, why is the argument (ω t − k ⋅ r) always subtracted? I think this is because if it were positive (ω t + k ⋅ r) the wave would travel backwards, but this is also not stated so I'm not sure. Thanks.

Regarding:

In special relativity, one can utilize an even more compact expression by using four-vectors:

   The four-position R = ( c t , r ) 
   The four-wavevector K = ( ω c , k ) 
   The scalar product K ⋅ R = ω t − k ⋅ r — Preceding unsigned comment added by Dugclaws (talk • contribs) 17:16, 28 October 2016 (UTC) 

Yes, correct, the expression is for a forward travelling wave if k is in the same direction as r. For the version of the equations which use a scalar k rather than a vector, a plus sign would indicate a wave travelling backwards. This kind of notation is used for analyzing transmission lines for instance, where the wave is restricted to travelling in only one of two directions. However, when using a vector k a backward travelling wave can be represented by pointing k in the opposite direction to r (or it can be pointed in any other direction at all). There is thus no need to have two different forms of the equation if vectors are used. SpinningSpark 21:35, 28 October 2016 (UTC)

Largest fragrant flower

What is the largest fragrant flower in the world (in terms of diameter, flower weight or both)? I mean with pleasant smell, unlike Rafflesia, etc. Thanks in advance. --93.174.25.12 (talk) 17:39, 28 October 2016 (UTC)

Besides Rafflesia, Amorphophallus titanum also has huge flowers (I'm pretty sure the name means "giant floppy dick", which brings me no end of giggles), but also apparently stinks of decomposing flesh. Reading through a few "listicles" of large and unusual flowers suggests the largest "non-rotting-dick-smelling flower" in the world may be the common sunflower, or Helianthus annuus; some of the domesticated breeds have very large flowers, this image search here turns up sunflowers whose central pod, not including the outer ray petals, exceed 16 inches (40 centimeters). It, of course, depends on how one defines a "flower", the term in common speech differs greatly from the botanical definition. See flower and Plant reproductive morphology for some of the background. --Jayron32 18:15, 28 October 2016 (UTC)

The sunflower, however, does not smell, not to mention it's not fragrant. 93.174.25.12 (talk) 19:10, 28 October 2016 (UTC)

I can smell them. --Jayron32 21:01, 28 October 2016 (UTC)

I think "giant misshapen penis" is probably a better translation to modern English. A-morphos - without clear shape. SemanticMantis (talk) 20:08, 28 October 2016 (UTC)

Except wikt:amorphous doesn't mean misshapen, just "does not hold a regular shape" Hence, floppy. --Jayron32 21:07, 28 October 2016 (UTC)

Ok, you are free to translate however you like, I was merely offering an alternative. A. titanum are not floppy, by the way, they are rather firm in fact, due to turgor pressure. Perhaps "unshapen" is a better word for 'amorphus', but translation is always a bit subjective. SemanticMantis (talk) 21:34, 28 October 2016 (UTC)

I think a more relevant point is both wiktionary which says "without form, shapeless, deformed" and our article "without form, misshapen" seem to imply misshapen or deformed is a resonable (I won't say better) translation. Whether this is correct or not I cannot say. And I assume we are talking about translation here, if the word is from the Ancient Greek ἄμορφος ‎(ámorphos) rather than the English amorphous, we potentially should be going by the Ancient Greek rather than the modern English meaning which may not be entirely the same (i.e. a form of false friends). Although scientific names can be complicated, as people may be thinking of the English word, look for a Latin, Greek or whatever alternative etc rather than studying the meaning of the Greek or Latin word that well. Then again, Amorphophallus was first scientifically described and I assume named in 1878 by an Italian botanist. Nil Einne (talk) 09:31, 29 October 2016 (UTC)

No, obviously, it's glassy rather than crystalline. —Tamfang (talk) 20:17, 29 October 2016 (UTC)

Also yes, to clarify, sun flowers have rather large inflorescences, but rather small flowers. The Asteraceae and a few other families an especially uncommon/derived inflorescence, called a Pseudanthium. SemanticMantis (talk) 20:59, 28 October 2016 (UTC)

When I stated "it depends on how one defines a "flower", the term in common speech differs greatly from the botanical definition" what I meant by that was "it depends on how one defines a "flower", the term in common speech differs greatly from the botanical definition." Just in case that was unclear. — Preceding unsigned comment added by Jayron32 (talk • contribs) 21:03, 28 October 2016 (UTC)

And the concept of nested quotation marks continues its slow death. —Tamfang (talk) 20:19, 29 October 2016 (UTC)

• All flowers smell pleasant, that's why they do it. It's just a question of audience. To a bluebottle, rafflesia is delightful. Andy Dingley (talk) 19:19, 28 October 2016 (UTC)

Some water lilies are about the size of that sunflower (um no my imagination getting the better of me Victoria cruziana) grow to about 25cm and they do have a light pleasant scent. Plus I think one can get a lotus growing to about the same size as a water lily flower. Dmcq (talk) 19:21, 28 October 2016 (UTC)

Individual Cattleya warscewiczii orchid flowers can reach 11" across [15], and there are usually several (up to 10) of them per spike (inflorescence). Several Cattleya hybrids are also in the same ballpark of size. By weight - I need to look up the literature, but Stanhopea tigrina flowers are quite massive (albeit short-lived). Several other orchids (e.g. Angraecum sesquipedale) have flower parts that are very long, and have a pleasant smell, but I'm not sure that's what the OP is asking. Dr Dima (talk) 23:32, 28 October 2016 (UTC)

note to self: I need to fix a bunch of our orchid pages, they are ridiculously lacking in content. I'll try to do this over the weekend, unless life happens. Dr Dima (talk) 23:36, 28 October 2016 (UTC)

How about Magnolia grandiflora? The article says the flowers are up to 12 inches in diameter, and I know they are fragrant. -Arch dude (talk) 16:29, 29 October 2016 (UTC)

Largest inflorescence is the talipot palm which does have an odor. Stinking Corpse lily is rather large too. EvergreenFir (talk) 17:14, 29 October 2016 (UTC)

October 29

component type ID

what is this diode(?) ? On the PCB, the designator is SGxxx and the symbol is like this: o---><---o
Thanks everyone in advance! Asmrulz (talk) 03:37, 29 October 2016 (UTC)

The colour band numbering suggests 53±2%. If it was a diode you would put "1N" on the front. 1N532, but since the red is offset it looks more like a tolerance. THis may not be a diode. Graeme Bartlett (talk) 04:01, 29 October 2016 (UTC)

It might be a transient-voltage-suppression diode. Though at first I thought it looked like a fuse: http://www.slimlab.net/mirror/fusecolours/fusecolours.htm but the colours don't decode to anything. Graeme Bartlett (talk) 04:29, 29 October 2016 (UTC)

I don't think this looks much like a diode. The internal structure looks much more like a resistor, although the clear glass packaging would be unusual. If it is a resistor, I don't think the offset red band is a tolerance, resistor colour codes are a minimum of three bands and this has only three. More likely the offset is to indicate which end to read it from. I would also read the centre band as brown rather than orange; 53 is not a preferred number whereas 51 is on the E24 series. That would make its value 5.1kΩ. Have you tried measuring it?

I have seen diodes colour coded in this way, for instance the common 1N4148 diode is marked with Y-BN-Y-S colour bands by some manufacturers, and the "1N" is just implied. However, 1N512 is a large diode with a threaded stud. SpinningSpark 09:29, 29 October 2016 (UTC)

It feels plastic-y and doesn't measure as anything (open loop) in either direction Asmrulz (talk) 10:08, 29 October 2016 (UTC)

If that's the case it would not be a fuse, diode or resistor. (but could be a blown fuse.) transient-voltage-suppression diode is still possible as it will only conduct when the voltage is high. Graeme Bartlett (talk) 12:56, 29 October 2016 (UTC)

The pictured component is a spark gap surge protector. [16] AllBestFaith (talk) 12:58, 29 October 2016 (UTC)

Yup, put a coil across it, is arcing. Thanks everyone Asmrulz (talk) 14:07, 29 October 2016 (UTC)

Best substance to absorb moisture from a damp item upon contact

I am looking for a substance that will absorb moisture directly from a damp item upon contact. I have been looking into desiccants (specifically activated carbon because of it's easy regeneration properties and additional odor removal characteristics) as well as super absorbent polymers. However, the only evidence I can find regarding desiccant moisture absorption is dealing with removal of moisture in the air and the SAPs absorbing liquid that has been directly poured onto the polymer.

Is there a material out there that can remove moisture from a damp item? Preferably a material that can be reused and can maintain it's absorption properties if contained in a non-woven/fabric covering. — Preceding unsigned comment added by 146.88.42.76 (talk) 04:51, 29 October 2016 (UTC)

Powdered calcium chloride can do this, but it's not reusable. 2601:646:8E01:7E0B:411:FA40:3178:507F (talk) 06:36, 29 October 2016 (UTC)

• Are you concerned about transfer of the dessicant to the item? Calcium chloride would be a problem there.

I would look at fuller's earth. This is cheaply available as cat litter (the grey mineral cat litter) and can be powdered further in a coffee grinder (cheap whirling blades type). It's inert, absorbent and can be regenerated by oven drying.

I'd also consider using a towel. This is already "its own fabric covering" and can be applied and removed cleanly and easily. Well laundered (older) cotton towels are fairly fibre free, and microfibre fabrics work well too. Andy Dingley (talk) 09:24, 29 October 2016 (UTC)

Sawdust or fine wood chippings, possibly, if it's dried out after use.--TammyMoet (talk) 10:38, 29 October 2016 (UTC)

Vermiculite is often used as an absorbent. --Jayron32 10:47, 29 October 2016 (UTC)

It would help if you inform us of what the item was. For instance, once having finished the wet process of making gunpowder one uses distilled alcohols for fast desiccation before the nitrate can form large crystals. If you have been looking at polymers, you will ready know about how to rejuvenate silica-gel in order to use it again. Then there is vacuum freeze drying and many other techniques. However, there is not one method that suits all cases. --Aspro (talk) 12:20, 29 October 2016 (UTC)

Indeed. Fuller's earth will work great on some items, while ShamWow may be more effective on others. Drying cabinet may be the best bet for other things. SemanticMantis (talk) 15:27, 29 October 2016 (UTC)

Disposable diapers are designed for contact moisture removal. If the moisture is clean water only, the diaper can be dried and reused, but it may be more cost-effective to just throw it away. If you have ever fished a diaper out of the toilet after baby throws it in there as a experiment, you know how much water a diaper can hold -Arch dude (talk) 16:22, 29 October 2016 (UTC)

A hypothetical idea

Suppose a universe has four spatial dimensions, but gravitational force is not proportional to acceleration, but to jerk. Would there be stable orbits? 93.142.81.244 (talk) 18:16, 29 October 2016 (UTC)

See Anthropic principle#Spacetime and the linked articles for our coverage of this issue. Tevildo (talk) 18:29, 29 October 2016 (UTC)

But there the force of gravitation is still mass × acceleration, so the gravitational acceleration is constant. I'm talking about mass × jerk, where the Δacceleration would be constant. For example, suppose a jerk of j = 1 m/s³ is applied to a standing body. After five seconds, a = jt = 5 m/s², v = jt²/2 = 12.5 m/s, s = jt³/6 ≈ 21 m. I wonder if that could solve the instability of orbits. I suppose this is useless in our own universe, where acceleration is constant but I wonder if anyone has tried this? 93.142.81.244 (talk) 18:43, 29 October 2016 (UTC)

Do athletes live longer?

Another thing that has been bugging me. Exercise is supposed to be healthy and increase our lifespan, and who exercises more than the athletes? But the thing is, when you exercise you breathe in more air, which contains lots of O₂. Similarly, if you drink more water, which is also something that athletes do and is supposed to be healthy, you drive extra oxygen atoms through your body. Shouldn't all that oxidation kill us faster? 93.142.81.244 (talk) 18:30, 29 October 2016 (UTC)

One leading cause of death is heart failure (alongside cancer). Sport can considerably help here. Add to it that other pretty common causes of death are diabetes and simple falls. Sport also reduces the incidence of this. If you are active, you also have a lower chance of developing dementia.

Do not assume though that the more sport you do the healthier you are. Professional athletes might have a shorter lifespan compared to reasonable active people who bike, walk, play soccer, and lift moderate weights. Going to the extreme can also be pretty bad. Sumo wrestlers might have a lifespan 10 years below average, for example. Llaanngg (talk) 18:37, 29 October 2016 (UTC)

Well, I'd expect injuries from full contact fighting sports to overwhelm any benefits. 93.142.81.244 (talk) 18:50, 29 October 2016 (UTC)

Well, that was a useless pile of personal opinion. Changes to life expectancy due to athleticism has been studied quite a bit. For example here is a meta-study that examines 54 primary studies regarding the life expectancy of athletes. It goes into some detail and has a sizable bibliography for your perusal. This article discusses some of the factors that probably lead to the greater lifespan. And here's an easy-to-read newspaper article that relates the basics of a smaller study involving Tour de France competitors. If you're interested in the negative health effects of oxygen, our article at oxidative stress is a pretty good start. Presumably, the health benefits outweigh the problems, but I didn't immediately find anything the discussed that particular topic directly. Matt Deres (talk) 18:57, 29 October 2016 (UTC)

Personal opinion? Amazingly what I said, although did not have more than one source can be corroborated even by your sources: "Physical activity reduces many major mortality risk factors including arterial hypertension, diabetes mellitus type 2, dyslipidemia, coronary heart disease, stroke"Llaanngg (talk) 19:19, 29 October 2016 (UTC)

Yes, a lot of damage is caused by metabolism, but almost all that damage has to be repaired, otherwise we would not live very long (if you shut off the self repair mechanisms in a healthy teenager, that teenager would look like a 100 year old within a few years and then die). So, longevity comes down to how well the body is capable of repairing itself. This has a strong genetic component, which explains why many super centenarians (people who have lived beyond the age of 110) actually did not stick to healthy lifestyles (most people do not stick to healthy lifestyles, the super centenarians are a self-selected group out of the pool containing everyone who happen to have good genes for self-repair). E.g., Calment smoked cigarettes from the age of 21 (1896) to 117 (1992). So, the huge damage done by smoking which would have caused most people to not reach their maximum possible age, did not significantly affect her, because the repair mechanisms at work in her body repaired the damage done by smoking much better than in most other people, without that mechanism at work in her body she would not have reached anywhere near her record breaking age, even if she had lived according to the most healthy lifestyle you can imagine.

Now, if you exercise a lot, then you will do a lot more damage to your body. But note that the reason why exercise improves physical fitness is due to the body repairing itself. After damage has been done the body will not simply restore itself in its previous state it will go beyond that making itself stronger than it was before. A system that has to maintain itself would not be stable if the extra repairs in response to more damage done, would not lead to it becoming a bit stronger. Damage done via exercise is extra damage on top of all the processes in the body that lead to decay. The body is constantly at work to counter these processes. Exercise will stimulate the self-repair mechanisms, the ramped up metabolism will do more damage, but the net effect of all processes taken together is that your body becomes stronger and fitter. Longevity will increase provided you stick to your exercise routine well into old age. Genes that in people destined to become super centenarians are always switched on by default, may be switched off in normal people by default, but they can be switched on if you exercise a lot. While the variant of these genes may be different in non-super centenarians making them less effective, it will still be a huge benefit to switch them on. So, it's best to stick to Jack LaLanne's routine and keep on exercising. Count Iblis (talk) 19:02, 29 October 2016 (UTC)

• This and this provide a few different perspectives on the matter. --Jayron32 20:38, 29 October 2016 (UTC)

To focus purely on one thing in the OP: drinking more water doesn't really "drive extra oxygen atoms through your body". It is technically true, since water molecules contain oxygen atoms, but your body doesn't split water molecules apart to get at the hydrogen and oxygen. Respiration actually produces water. Plants, and other photosynthetic organisms, are the ones that take up water to use it as an electron donor, yielding oxygen as a waste product. The reason you need to drink water is to replenish excreted water. --47.138.165.200 (talk) 21:47, 29 October 2016 (UTC)

Is the a/c ventilation system ever big enough so that a person can move through it?

How big can the ventilation system of a/c be? Or is this just a reality bending for movies? --Llaanngg (talk) 18:30, 29 October 2016 (UTC)

IIRC, Mythbusters once did an episode about it. It turned out to be impractical even if possible, because anyone moving inside it made a lot of noise, and sound travels very well through metal tubing. 93.142.81.244 (talk) 18:48, 29 October 2016 (UTC)