I have 2 questions: 1. Does the heart have nervous? 2. Is the electrical conduction system is considered nervous? 149.88.6.66 (talk) 08:27, 6 May 2015 (UTC)[reply]

Yes and probably yes (the nervous system is electric, but non-animal electrical systems use wires, not nerves). InedibleHulk (talk) 11:36, May 6, 2015 (UTC)

The nervous system uses a combo of electricity and chemistry to send signals (the chemistry portions slows things down quite a bit). StuRat (talk) 16:49, 6 May 2015 (UTC)[reply]

The heart contains a number of small ganglia (clusters of nerve cells), and also the cardiac plexus, a network of nerve fibers that distribute signals to various parts of the heart. But most likely the question relates to the network of Purkinje fibers, which are sometimes thought of as the heart's private nervous system. The rhythmic beating of the heart is controlled by a small portion called the sinoatrial node. Signals from the SA node are rapidly conveyed to other parts of the heart by Purkinje fibers, which are muscle cells that are modified to function like nerve cells: they are very long and thin, and capable of conducting electrical signals efficiently. Looie496 (talk) 12:33, 6 May 2015 (UTC)[reply]

• 1.There are nerves that go to and near the heart. 2. No. The conduction system of the heart is not considered nervous tissue.--Mr.Pseudo ^{Don't talk to me} 14:04, 9 May 2015 (UTC)[reply]

• 2) Why not ? Electrical pulses sending signals through the body would seem to qualify. StuRat (talk) 15:03, 9 May 2015 (UTC)[reply]

"The conducting system of the heart consists of cardiac muscle cells and conducting fibers (not nervous tissue) that are specialized for initiating impulses and conducting them rapidly through the heart (see the image below)." 1. "The AV node is a highly specialized conducting tissue (cardiac, not neural in origin) that slows the impulse conduction considerably" 2. --Mr.Pseudo ^{Don't talk to me} 19:52, 9 May 2015 (UTC)[reply]

P.s: It is a typical question on med school (anatomy exam). :D --Mr.Pseudo ^{Don't talk to me} 20:00, 9 May 2015 (UTC)[reply]

FOX News isn't exactly a reliable source, but they cite this to Garth Illingworth, author of the paper about the discovery of EGS-zs8-1, estimated at 670 billion years after the Big Bang and the furthest/oldest galaxy known. The problem is, I don't know of any kind of matter creation in the matter-dominated era apart from the mysterious self-creation of dark energy, which isn't that dominant in the cosmos even if you count it - though I suppose that the condensation of galaxies and stars must have liberated substantial heat/light in the form of photons, relativistic mass, occasional particle-antiparticle pairs, and increased mass (as measured from close by) in supermassive black holes vs. their component bits due to all the fast-moving particles eaten. Still, I'd expect the mass of a collapsed galaxy cluster or uniform dust that might have preceded it would look the same from far off, so counting that also seems dubious, and again, I doubt it's enough. So can someone explain what this quote is about, or verify that it is an unfortunate news incident? Wnt (talk) 11:29, 6 May 2015 (UTC)[reply]

670 million, not billion. Dragons flight (talk) 13:15, 6 May 2015 (UTC)[reply]

The confusion is with Fox's quarterly profits. Thincat (talk) 13:31, 6 May 2015 (UTC)[reply]

I'm no astrophysicist, but it seems there was a time when atoms were split into electrons and nuclei. Still stuff (in a way), but no atomic mass. As they gradually cooled back into atoms, there must have been a point when only five hundredths were finished. InedibleHulk (talk) 11:51, May 6, 2015 (UTC)

That's not how atomic mass works, and is not restricted to atoms, all matter has mass. 'Atomic mass' is not a mass of atoms, not is it the mass contributed by atoms in general, it is a measurement of the mass of a precise number of atoms of a particular element. Plasmic Physics (talk) 12:02, 6 May 2015 (UTC)[reply]

That's why I started with the disclaimer. Anything useful at all in that reference?

As for the sort of thing I do know about, splitting off a description of the Dark Ages with commas can make it seem like Illingworth described the time that way, rather than just saying it was from after that time. Not sure if that's the case here, but it happens. InedibleHulk (talk) 12:48, May 6, 2015 (UTC)

The disclaimer even more enigmatic, because atomic mass is not an astrophysical term in the first place. No, there is nothing relevant in the reference that pertains to answering the question. Plasmic Physics (talk) 03:00, 7 May 2015 (UTC)[reply]

I can't parse that in any way that seems reasonable to me, so I'm going to assume that it is simply a scientist-to-reporter communication snafu. Dragons flight (talk) 13:15, 6 May 2015 (UTC)[reply]

Well, I'm a little late to this discussion, but Wnt, you're already off the track: why are you reading Fox News for science information?

Among my many (free!) subscriptions, I receive a newsletter from the Keck Observatory: you can subscribe too! You'll never have to rely on second-hand media to incorrectly report science information a few days late. Isn't it wonderful that we have a new format for mass media dissemination with the potential to shake up the old conglomerates? Why are you using this innovative technology to perpetuate an archaic media model, when you could be using it to go straight to the sources of new information?

A few days ago, Keck Observatory broke this news, and here is their press release: Scientists at Keck Measure Farthest Galaxy Ever. Oh hey, it's even got a link to more technical information, and guess what quote is not used by the authors? The very same quote that is confusing User:Wnt! That confusing information was added by a non-scientist, probably by Fox's freelancer or staff reporters.

Observational astronomers who study deep sky objects talk about redshift by z number, not by mass-of-universe-as-a-ratio-to-current-value. The authors of this paper mention z > 6, which is quite distant, quite old. Z number is a directly observable quantity.

Once you have a Z (7.7, in this case), then you, or your favorite cosmologist, or your favorite Fox News reporter, can plug this value into your favorite cosmological model, and then you can chug out a "distance" or an "age" or a "mass of the universe," but that is a model result, not an observed quantity. That output is meaningless unless you specify what calculation you used, or which standard model you applied.

Hopefully, you can see that this is a problem of construction: the more you depend on non-experts to provide second-hand, pre-digested sources of information, the farther your mental model deviates from the actual practice of science. Resultantly, you will have a more difficult time trying to consume or intuit these strangely-reported "scientific" results!

Nimur (talk) 13:23, 6 May 2015 (UTC)[reply]

Actually the same strange statement appears in the Associated Press story, so it probably isn't Fox's fault in this specific case. (The Fox story says that Associated Press reporting was used in their footnote.) Dragons flight (talk) 13:36, 6 May 2015 (UTC)[reply]

Well, that explains it. The AP's chairman is junk. Or wait, no. Junck. But "chairman" is no typo, despite the sort of biology even I understand.

Anyway, this is science today. As to whether perception is reality, I'd need to study sellers. I mean, Sellars. InedibleHulk (talk) 14:21, May 6, 2015 (UTC)

I assume what they meant to say is that the universe was about 1/500 of the size it is now (and the mass density was 500 times higher). The AP article also wrongly says that the galaxy is 13.1 billion light years away. The reporter probably made that up based on the light travel time of 13.1 billion years, but it doesn't work that way. A correct figure would be around 29–30 billion light years.

If any Associated Press science reporters are reading this, Ned Wright's cosmology calculator will calculate this stuff for you. Enter the redshift into the box labeled "z", and click "Flat". The "comoving radial distance" is the distance you should report, and the size (volume) of the universe back then as a fraction of its current size is (angular size distance / comoving radial distance)³ 1/(1+z)³. -- BenRG (talk) 17:29, 6 May 2015 (UTC)[reply]

I'm pretty sure that z = 7.7 doesn't work out to 1/500 of the volume either. Dragons flight (talk) 18:05, 6 May 2015 (UTC)[reply]

Actually of course there's an easier way to calculate the size ratio: 1/(1+z)³. Using z=7.73 from the paper, that's about 1/665, but Illingworth could plausibly have rounded it to 1/500. -- BenRG (talk) 18:34, 6 May 2015 (UTC)[reply]

BenRG, is this method to calculate size-ratio a standard method for which you can cite a source, or is it your own interpretation of the math? Nimur (talk) 11:34, 7 May 2015 (UTC)[reply]

Here are some papers that say that 1/(1+z) is the scale factor. You can work out that D_A/D_now = 1/(1+z) in a flat universe from this with a little algebra. (D_A and D_now are angular size distance and comoving radial distance, and Ω_tot = 1 in a flat universe, and I could find a reference for that but you can probably just google it.) The formula I crossed out isn't wrong, just more model-dependent. 1/(1+z) doesn't assume a flat universe and, as you said, z (always lower case, by the way) is a more directly measurable quantity. -- BenRG (talk) 18:38, 7 May 2015 (UTC)[reply]

Yes, they are correct. The universe cools as it expands. Matter, as it's used here is juxtaposed against energy, not as a form of it. Whence the creation rate of stars is much greater and the wavelength of light emitted from these processes is blue-shifted (it's hotter - the red shift is distance) . I suspect that the periodic table of natural elements was much smaller and much less abundant 13 billion years ago. As the universe aged, matter was created through star processes. --DHeyward (talk) 07:40, 8 May 2015 (UTC)[reply]

If humans don't keep their rear ends clean, they get inflamed and then infected. We wipe ourselves to keep the area clean. How do our [close] relatives in the animal kingdom deal with this problem? It occurred to me that having fur in that area may be a help or a hindrance. --Dweller (talk) 13:27, 6 May 2015 (UTC)[reply]

Is that why baboons have such shiny red asses? --Jayron32 13:53, 6 May 2015 (UTC)[reply]

The other apes do not really have buttocks in the manner that we do - that's a result of our bipedalism - so they have no more problems with keeping their anal regions clean than other animals do. I believe some mammals prolapse their rectums slightly to further ensure it's a clean emission, but I don't know if any apes do that. Free tip: don't Google the term "prolapsed rectum" unless you really think you need to. Matt Deres (talk) 14:01, 6 May 2015 (UTC)[reply]

Thanks for the tip. So bipedalism seems to be dependent on having the ability to somehow clean buttocks? Are there no other bipedal creatures? Ummmm, how did T-Rex clean its backside? --Dweller (talk) 14:13, 6 May 2015 (UTC)[reply]

Tiny arms would have made it difficult to use toilet paper. Maybe he got the triceratops to help him out with that big horn of his. --Jayron32 14:16, 6 May 2015 (UTC)[reply]

There are other bipedal creatures of course, but they have different musculature (such as the presence of tails). In birds, the feces rather infamously gets shot out the cloaca mixed with urine, so that it slides out with minimal mess. I believe it was in The Private Life of Plants that David Attenborough talked about a parasitic plant species that produced berries with extremely sticky pulps. Birds loved the berries, but would have to wipe their rears onto tree branches to remove the mess, thus placing the seed exactly where it needed to be to parasitize the next plant. Matt Deres (talk) 15:48, 6 May 2015 (UTC)[reply]

Everyone should watch that series, regardless of the question. InedibleHulk (talk) 16:00, May 6, 2015 (UTC)

Hello,

I've been advised to bring this to science desk. Can someone help me catagorising this please, as much as you can...whatever relates with whatever... -- Mr. Prophet (talk) 18:55, 6 May 2015 (UTC)[reply]

Your link doesn't work. Try [1] or Wikipedia:Reference desk/Language#Categorizing help. However I think you've strongly misunderstood the comments there. No one was seriously suggesting you bring it here. What they were suggesting is that if you asked the question here, it's likely to get an even poor response because what you're asking about is completely unscientific and this is the science desk not the utter nonsense desk. Nil Einne (talk) 19:01, 6 May 2015 (UTC)[reply]

Yes Nil Einne, COMPLETELY! Thank you for waking me up, I forgot that Wikipedians use the subscript code to joke around sometimes (including myself who started using it recently). Regards. -- Mr. Prophet (talk) 19:14, 6 May 2015 (UTC)[reply]

I suggest that you just guess at the categories, and it is unlikely that you will be proved wrong. Dbfirs 20:13, 6 May 2015 (UTC)[reply]

Thank you thank you thank you! -- Mr. Prophet (talk) 08:43, 7 May 2015 (UTC)[reply]

Palmistry.
Sleigh (talk) 03:44, 7 May 2015 (UTC)[reply]

I tried it, I hate other websites too. I sometime correct my notes with it... Thank God people in Wikipedia (or Wikipedia users) are all good! Evil prevails where I'm, people would rather learn the vice part more than the virtious part. -- Mr. Prophet (talk) 08:43, 7 May 2015 (UTC)[reply]

Could it be that dark matter and dark energy necessary exists, only because the speed of light in a vacuum and/or other values are assumed to be constants? I recall an unexplained discrepancy, when the LHC experimentally determined the mass of a proton, and found it to be in disagreement with the established value. Could the speed of light actually be dependent on distance, where a small change only becomes noticeable over galactic distance? Plasmic Physics (talk) 01:15, 7 May 2015 (UTC)[reply]

Sure, why not? --Jayron32 01:43, 7 May 2015 (UTC)[reply]

Surely there must be a logical reason why I've not heard of any such idea investigated by a prominent scientist. I would consider this a case in point of Occam's Razor - conceding an error of assumption is a far simpler path than inventing mysterious matter and energy, and deriving all the physics involved. Plasmic Physics (talk) 02:49, 7 May 2015 (UTC)[reply]

Why do you think that the proton mass or dark matter and energy have anything to do with a variable speed of light? No one has investigated this idea because it isn't an idea, just a juxtaposition of headlines you saw in Discover magazine. -- BenRG (talk) 07:50, 7 May 2015 (UTC)[reply]

That was something close to what I was thinking, but then again, who knows. PP, if you have a mechanism in mind according to which a variable speed of light would explain the observations that induce cosmologists to postulate dark matter and dark energy, please do enlighten us.

Actually, since the two things (dark matter and dark energy) have basically nothing to do with one another except the word "dark" and the fact that we don't know their origin or composition in detail, maybe just pick one of the two and start with that. --Trovatore (talk) 08:08, 7 May 2015 (UTC)[reply]

I don't have a mechanism in mind, but there is clearly a link, since the speed of light features in virtually all formulas relevant to cosmology. The gravitational constant is it self a function of the speed of light. All that remains is to find the dependency of the speed of light on space-time. I raised the point about the proton mass to exemplify how another constant is not so constant after all, it's not only LHC that reported a discrepancy, a few observatories also gave similar reports when studying the more distant gas clouds. Plasmic Physics (talk) 08:35, 7 May 2015 (UTC)[reply]

The speed of light is important because of basic relativistic mechanics. Since all motion is relative to the speed of light, it will show up in any calculation where anything moves. Which is pretty much every physics calculation--Jayron32 13:00, 7 May 2015 (UTC)[reply]

Not just relativity, but most electromagnetic phenomena also depend on the speed of light. The absorption and emission spectra of atoms are considered one place where changing physics might reveal itself over time. People have looked for that, and perhaps the best that can be said at the present is, if there is any variation in electromagnetic coupling over space/time then the variation isn't very large (no more than parts per million). Dragons flight (talk) 16:14, 7 May 2015 (UTC)[reply]

Well, exactly my point. Is something moving, or have the potential to move in electromagnetism? If yes, speed of light will enter into the calculations. Since physics = the science of motion, the speed of light is a fundamental concept that will show up in almost every single calculation somewhere. --Jayron32 16:16, 7 May 2015 (UTC)[reply]

Blood is in virtually every part of the human body, so cancer and asthma and this other disorder that's in the news must be related to blood, and we could cure them by reducing the amount of blood. Physicians should investigate that, but maybe they're reluctant to admit that their careers have been a lie.

The proton discrepancy that you're talking about is presumably the discrepancy in the charge radius. Maybe you read this article which says "proton mass" in the headline even though it talks about size in the body, suggesting that Discover's editors don't know the difference between mass and size, which is pretty bad even by the usual awful standards of these publications. Different attempts to measure the charge radius by different methods give inconsistent results. Since they don't measure the radius directly but rather calculate it from indirect evidence, the natural explanation is that there's an error in the calculations. It could be a sign of new physics (rather than just a simple error), but even if it is, it's new physics that invalidates their calculation of the radius, not new physics that means the radius is not constant. -- BenRG (talk) 17:29, 7 May 2015 (UTC)[reply]

See variable speed of light. --Modocc (talk) 14:29, 7 May 2015 (UTC)[reply]

Thank you. I didn't know we had an article on that, although I should have guessed, since WHAAOE. Plasmic Physics (talk) 21:33, 7 May 2015 (UTC)[reply]

In online forums and blogs (and occasionally in mainstream press articles), I sometimes hear the claim that certain peoples in various Asian countries try to inflict as much pain as possible on dogs and other animals before they slaughter them. The reason given is that this somehow makes their meat taste better. Western travelers to remote areas claim to have witnessed this pratice first-hand.

But to me, it sounds like a strange claim, as I've heard that slaughterhouses in America try to keep animals calm, not for humane reasons, but because if the animal is frightened, it somehow degrades the quality of the meat.

I've heard further claims that those two slaughter methods are not necessarily contradictory and that the beating/torture technique is intended to stimulate all the meat-ruining adrenaline so that it can then leave the system, after the animal has been sufficiently beaten,leaving the meat pure.

I find these claims are as poorly sourced and sketchy as they are shocking. Is there anywhere I can read a dispassionate description of this practice as well as whether there is any science behind it (i.e., beating or not beating an animal and its effect on the taste/texture of meat)? When I google it, all I can find are very emotional and sensationalist accounts by animal welfare groups, who are very rightfully upset, as it's a very cruel practice. But I don't need to be told it's cruel (that seems obvious, at least to those of us in the West who are socialized to care about dogs)--I am just wondering if there's any actual utility/purpose to the practice.

In short, do people really do this? Is there any evidence that it works?--Captain Breakfast (talk) 09:35, 7 May 2015 (UTC)[reply]

Hi There is a good body of science behind keeping animals as calm and unstressed as possible before slaughter. Excessive stress before slaughter can lead to a condition called PSE meat. In addition, having stressed animals before slaughter can lead to them becoming more aggressive and bruising each other. Both can be extremely costly. As for beating animals before slaughter, I do not know of this. But, it could certainly change the texture of the meat - but bruised meat is generally thought to be less palalatable (at least in Western culture). I don't think beating would be succesful at ridding the body of adrenaline as the body can produce adrenaline de novo under conditions of stress, e.g. by beating. So, I doubt the body would ever be rid of adrenaline.DrChrissy ^(talk) 11:46, 7 May 2015 (UTC)[reply]

I would expect that beating animals would result in blood in the muscle tissue. Most Westerners don't like the taste of blood (the iron specifically makes it taste bad), but I suppose others might, particularly if they were deficient in iron (bone marrow is a good source of blood, too). Of course, there are easier ways to mix blood with meat, and blood rapidly goes bad, so doing the mixing immediately after the blood is removed from the animal and right before cooking would make the most sense. Also note that it isn't necessary to slaughter an animal to get blood from it. I believe there's a tribe in Africa that keeps cattle, and draws some blood to mix with milk to make a drink. StuRat (talk) 12:01, 7 May 2015 (UTC)[reply]

That would be the Maasai people. DMacks (talk) 14:38, 7 May 2015 (UTC)[reply]

Yep, that's them. Thanks. StuRat (talk) 21:38, 7 May 2015 (UTC)[reply]

@ StuRat "Bone marrow is a good source of blood too", Really? have you ever seen or eaten bone marrow? not much blood at all, mostly gelatine and fat cells. Richard Avery (talk) 07:30, 8 May 2015 (UTC)[reply]

Perhaps I should have said iron. That's where red blood cells are formed, and it has a definite metallic taste as a result. StuRat (talk) 01:01, 9 May 2015 (UTC)[reply]

It certainly is a belief that stress hormones tenderise the meat (not the bruising of the meat) see:here. I was also told once by a vet who worked in the meat industry in the UK that people who steal deer to sell as venison like to chase them around before they shoot them as they believe it will make the meat is more tender. I don't expect that much scientific research has been done on this as it would be difficult to construct an ethical experiment. Richerman (talk) 13:34, 9 May 2015 (UTC)[reply]

Human women who nurse are subject to osteoporosis. As I understand it, calcium is removed from the bones to add to the milk. So then, does the same happen with cattle ? It seems that we force them to produce far more milk in their lives than is natural. If not, why not ? What protection do cattle have against calcium loss, and can this protection be extended to women ? StuRat (talk) 12:08, 7 May 2015 (UTC)[reply]

Hypocalcaemia, milk fever [2]. -- Finlay McWalterᚠTalk 12:13, 7 May 2015 (UTC)[reply]

I think you've made a false link. Women lactate; women are more subject to osteoporosis; therefore lactation causes osteoporosis. This, for example, says that osteoporosis is more common in older women, past the menopause: hardly a time of significant lactation. It cites hormonal changes as the major cause, and does not mention lactation at all.--Phil Holmes (talk) 16:14, 8 May 2015 (UTC)[reply]

Their bones are depleted of calcium both during lactation and after menopause. The cumulative effect of both can be brittle bones. And note that your assumption that the effect must occur concurrently or immediately after the cause is a logic error. Take shingles, which occurs years after having chickenpox, or cervical cancer, which can occur long after contracting HPV, or skin cancer, which can occur decades after getting severe sunburns. StuRat (talk) 16:21, 8 May 2015 (UTC)[reply]

I've provided a link from a Governmental health organisation that suggests no link with lactation. Could you cite some actual evidence for your unbased assertion?--Phil Holmes (talk) 19:46, 8 May 2015 (UTC)[reply]

Googling "calcium during lactation", I found quite a few entries, including this, which says calcium tends to be depleted both during pregnancy and lactation. Challenging facts is fine. Firing shots at fellow editors is not. ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:37, 8 May 2015 (UTC)[reply]

That link says that extra calcium is needed during lactation. It also says that this comes from milk, and the information is provided by "The Dairy Council", so no surprises there. However, the link provides no link between lactation and osteoporosis. Stu is continuing to make stuff up rather than provide properly referenced information. The shot I fire is that this supposed to be a reference desk, with information referenced rather than assertions that something is true because the editor thinks it might be.--Phil Holmes (talk) 09:09, 9 May 2015 (UTC)[reply]

Read through these studies: [3] and don't be so rude. If your goal in life is to insult people rather than answer questions, you don't belong here. StuRat (talk) 11:56, 9 May 2015 (UTc)

I'm not trying to insult you: merely to point out that you are quoting as fact something that appears simply untrue. Your initial statement is "Human women who nurse are subject to osteoporosis." I believe this to be completely false, based on the link I quoted and even the links you quote: the final one says that calcium deficiency from lactation is reversible and at most, a very minor possible cause of osteoporosis. Imagine that you were a mother about to give birth and followed a link to this ref desk and read that "Human women who nurse are subject to osteoporosis." If there was not a follow up statement pointing out that this has no basis in fact, you could end up changing the way mothers nurse their children, with likely adverse affect on their childrens' health - see, for example, this study on development in children and the effect of breast feeding. I would argue I belong here as a qualified scientist who checks references before inventing non-facts. Thanks for the insult, though.--Phil Holmes (talk) 15:44, 9 May 2015 (UTC)[reply]

"Completely false" and "a very minor possible cause of osteoporosis" are incompatible. If it's a cause, even a minor one, that's not "completely false". And that's all quite irrelevant to my Q, which was how cattle deal with the continuous loss of calcium from constant lactation. All of my sources showed that calcium loss does occur due to lactation in women. Whether this eventually leads to osteoporosis in women is a minor quibble, and we've wasted way too much time on it. I think me pointing out your logic error made you angry, and you decided to "get even". StuRat (talk) 23:39, 9 May 2015 (UTC)[reply]

Just looking through the abstracts of the studies you linked to, most of them say something along the lines of " Pregnancy-and lactation-associated osteoporosis is an uncommon condition that may be a consequence of preexisting low bone density, loss of bone mineral content during pregnancy, and increased bone turnover. So it's obviously not a general problem in lactating women and you wouldn't expect it would normally be a problem in cattle, providing they get enough calcium in their diet. Richerman (talk) 12:41, 9 May 2015 (UTC)[reply]

In women: The calcium loss in the bones often occurs, but only rarely rises to the level of causing osteoporosis during lactation. However, this calcium loss can set them up for osteoporosis later in life, post menopause, when additional calcium loss can occur, unless they replace the calcium in the bones after lactation: [4].

In cattle: My question here is based on dairy cattle producing far more milk than they would in nature, with little opportunity to replenish the calcium, post-lactation. StuRat (talk) 12:59, 9 May 2015 (UTC)[reply]

An example showing that breastfeeding can actually reduce the indicence of osteoporosis is here: "Another important element used in producing milk is calcium. Because women lose calcium while lactating, some health professionals have mistakenly assumed an increased risk of osteoporosis for women who breastfeed. However, current studies show that after weaning their children, breastfeeding mothers' bone density returns to prepregnancy or even higher levels (Sowers 1995). In the longterm, lactation may actually result in stronger bones and reduced risk of osteoporosis. In fact, recent studies have confirmed that women who did not breastfeed have a higher risk of hip fractures after menopause (Cummings 1993)."--Phil Holmes (talk) 16:06, 9 May 2015 (UTC)[reply]

If you read for Preventing Milk Fever in Dairy Cattle by Horst et al it says in the discussion:"Noticeably, milk fever is very rare in first lactation cows; incidence increases dramatically in third and greater lactations. Several factors contribute to the aging effect. Advancing age results in increased milk production, resulting in a higher demand for Ca. Aging also results in a decline in the ability to mobilize Ca from bone stores and a decline in the active transport of Ca in the intestine, as well as impaired production of 1,25(OH)2D3". It also discusses strategies for dealing with the problem. Richerman (talk) 13:21, 9 May 2015 (UTC)[reply]

What is the difference between primarily red with black dot-type ladybirds, and primarily black with red dot-type ladybirds? It might be an old wives' tale, but when I was a kid, I was taught that the black ones sting/bite. I've never been bitten nor stung by any kind, and we have loads of them in our gardens. KägeTorä - (^影_虎) (もしもし！) 13:04, 7 May 2015 (UTC)[reply]

Here's a link to ladybird ("ladybug" in the US). StuRat (talk) 13:15, 7 May 2015 (UTC)[reply]

They are just different members of the Coccinellidae, or even just different colorations of the same species (polymorphism_(biology)). To my knowledge, none of them are all that different in terms of behavior, with the exception of the asian ladybug, whose population has skyrocketed in the USA in recent years (also note the variety of colors/patterns in that species). They can be a bit of a pest, and swarm in to homes in the cool season. I don't think any beetle can sting, though ladybirds will bite on occasion (rather minor, no lasting mark or itching). My impression is that the asian ladybird beetles might be a little more likely to bite, but that may just be an artifact of the fact that they occur in bigger swarms, which would increase your chances of being bitten. SemanticMantis (talk) 13:19, 7 May 2015 (UTC)[reply]

Thanks, both of you. I didn't take it seriously, to be honest, believing it to be an old wives' tale. And Stu, I prefer the term 'ladybird', because 'ladybug' is the word I had to teach in Japan (as schools prefer American English), and to me it sounds like a venereal disease. 'Ladybird' sounds so much better, as a harmless little creature. KägeTorä - (^影_虎) (もしもし！) 13:35, 7 May 2015 (UTC)[reply]

(EC) SM, that link just reminded me of something we did as children, as a good luck charm. We get them to crawl onto our little finger, and then blow them away, making a wish at the same time. Is this practice common anywhere else? KägeTorä - (^影_虎) (もしもし！) 13:43, 7 May 2015 (UTC)[reply]

I see from the link that the asian beetle is indeed in the UK now, so you probably see mostly that type, though there will still be natives mixed in at lower concentrations. If you see more these days than when you were young, the explanation is probably the invasive species. Distinguishing the species is rather difficult for the non-expert, because color is useless, you have to look at the pronotum to make sure. Keep your eye out for the larvae, they look like fierce little dragons, and many people wouldn't recognize them as beetles [5]. As for names, I prefer "ladybeetle" - as it clearly indicates the beetle status ;) SemanticMantis (talk) 13:41, 7 May 2015 (UTC)[reply]

We used to recite "Ladybird, ladybird, fly away home, your house is on fire and your children are flown" while the ladybird was on the little finger, before blowing it and making a wish. There is an interactive UK ladybird spotter, as well as spotter charts and more information on the UK Ladybird Survey website. DuncanHill (talk) 14:05, 7 May 2015 (UTC)[reply]

I knew it wasn't a false memory. Thanks, Duncan! KägeTorä - (^影_虎) (もしもし！) 18:54, 7 May 2015 (UTC)[reply]

Huh. A variant of that line also occurs in Tom Waits' Jockey Full of Bourbon, but I never knew the referent. Listen here if you're interested [6]. SemanticMantis (talk) 21:05, 7 May 2015 (UTC)[reply]

Of course, we have an article: Ladybird Ladybird. In London, her "children are gone!" Alansplodge (talk) 21:36, 7 May 2015 (UTC)[reply]

I learnt that nursery rhyme in school in the US back during the Nixon Administration. We realized that ladybird was a mistake for the proper term ladybug from the illustrations. The only people who need feaar being bit by ladybugs are aphids. As for Ladybird, that is a title for the wives of American presidents. μηδείς (talk) 22:22, 7 May 2015 (UTC)[reply]

A personal anecdote, I know, but I was bitten by several ladybirds in the summer of 1976, when we had a veritable plague of them in the UK. It wasn't very painful, and it's true that they don't sting, but they are not entirely innocuous. Tevildo (talk) 18:10, 8 May 2015 (UTC)[reply]

You will find that in the article - with citations! Well - not that you personally were bitten, but people in general were see: Coccinellidae#Infestations and impacts And, of course, it's ladybug that's a mistake - they're not bugs at all. You wouldn't believe how much trouble the difference in names causes for that article. Richerman (talk) 19:08, 8 May 2015 (UTC)[reply]

I'll assume Cardinal Fang had the two of you in the comfy chair while this was going on? μηδείς (talk) 20:57, 10 May 2015 (UTC)[reply]

FWIW, I was always taught as a kid that the black-with-red-spots type were poisonous while the red-with-black-spots ones were harmless. There were some that were yellow with block spots too. I assumed that they were the red type that hadn't 'ripened' yet. --Kurt Shaped Box (talk) 22:05, 10 May 2015 (UTC)[reply]

Is there a connected multi-tooth veneer ? If so, does it still require an adhesive or grinding down the existing teeth ? Veneer (dentistry) doesn't list any. StuRat (talk) 14:28, 7 May 2015 (UTC)[reply]

Wouldn't a "connected multi-tooth veneer" be a "grill"? --Jayron32 15:50, 7 May 2015 (UTC)[reply]

Yes, except that as it says "Grills are made of metal". I'd looking for the same thing, but with white ceramic or other white material (titanium dioxide is both white and partially metal, but it reacts with calcium, so not a good choice here). StuRat (talk)

Atmosphere of Earth gives the Earth's oxygen content as 20.946%. Does it stay that constant? Bubba73 ^{You talkin' to me?} 17:48, 7 May 2015 (UTC)[reply]

No, neither as a percent composition nor as a total amount. For example, we just reached a global average of 400 ppm of CO2 in the atmosphere. If the relative proportion of one compound is on the rise, this impacts the relative proportion of other compounds within the atmosphere. Additionally, there are sources adding oxygen to the atmosphere, such as plant photosynthesis, and actions that remove it, such as combustion and aerobic respiration. These will all have their own impacts on the precise percentage of oxygen in the atmosphere. That said, all of these factors may be either well balanced or very small in impact to the point that, over the significant figures in your percentage, the number may not be changing. That is not the same thing as being a constant. --OuroborosCobra (talk) 17:57, 7 May 2015 (UTC)[reply]

CO₂ levels do not significantly affect oxygen levels. Look at the number you just quoted. CO₂ has risen to 400 ppm. That's parts per million. Oxygen is 20.946 %. That's parts per hundred. 400 ppm is 0.0400%, which means it would just start to budge the oxygen amounts, but not by much. While your general point may be sound (that is, the relative amounts of other gases DO affect O₂), significantly CO₂ is just not one of those gases. The Earth's atmosphere today is basically only 3 gases which have any individual statistical significance: nitrogen, oxygen, and argon (in that order). Everything not one of those gases only accounts for about 500 ppm, or 1 20th of one percent. The amount of oxygen does change dramatically as noted below, but only on very long time scales. An interesting article to read would be Great Oxygenation Event, which is believed to correspond roughly with the origin of life. --Jayron32 19:08, 7 May 2015 (UTC)[reply]

Don't forget water vapor... Short Brigade Harvester Boris (talk) 02:32, 8 May 2015 (UTC)[reply]

That's why I said the impact would likely be below the significant figures of the percentage given. Not sure what you are responding to since I had already said that. That said, 1/20th of 1 percent could actually put that in the significant figures of the percentage given (20.946% vs. 0.05%, or in the case of 400 ppm, 0.04%), so actually, CO2 level changes could be significant enough for the percentage of O2 given. After all, a change of 50 ppm (say for 350 ppm to 400 ppm) could be significant enough for a change from 20.941% to 20.946% O2. That would only work if the only other gas impacted was oxygen, of course, which I doubt. --OuroborosCobra (talk) 23:02, 7 May 2015 (UTC)[reply]

The small rate of decline of atmospheric oxygen is used to help us figure out the budget of CO2 produced by fossil fuel combustion. The decrease in O2 is consistent with the amount of oxygen needed to burn fossil fuels, reduced by a (somewhat uncertain) sink. See for example Keeling et al. (1996), Nature, 218-221. Short Brigade Harvester Boris (talk) 02:30, 8 May 2015 (UTC)[reply]

Additionally, the portion of oxygen in the atmosphere has changed over the course of the Earth's existence, including over the last several hundred million years. See Atmosphere of Earth#Third atmosphere and the figure at right. --OuroborosCobra (talk) 18:00, 7 May 2015 (UTC)[reply]

And for more short-term variations see this paper. If I am reading Fig.1 correctly, the seasonal variation is few 10s of ppm, with year-to-year variation being few ppms. So the last digit in 20.946% may vary by 2-3 within a year, and over a decade. Abecedare (talk) 20:28, 7 May 2015 (UTC)[reply]

One theory I've heard is that large dinosaurs required a high oxygen content in the air. So, did the age of large dinos correspond with the high points on the chart ? StuRat (talk) 20:18, 7 May 2015 (UTC)[reply]

Look at Dinosaur, which puts them appearing at 231 mya, dominant until 66 mya. Lungs are tricky though. It is true that higher concentrations of O2 allowed for bigger insects in e.g. the Jurassic. Here's a paper on the topic of the Paleozoic O2 spike and consequences for physiology and evolution [7] SemanticMantis (talk) 20:53, 7 May 2015 (UTC)[reply]

Based on the figure I posted above, oxygen levels do look to have been higher during the age of dinosaurs than today, as much as 30% or so vs. the 21% of today. Whether that enabled larger dinosaurs is another matter altogether. We have larger air breathing animals today, such as the blue whale. How much oxygen a whale needs vs. a dinosaur and indeed how much oxygen a dinosaur needed is well beyond my skills. --OuroborosCobra (talk) 23:06, 7 May 2015 (UTC)[reply]

Whales swim in the water, and I believe that's far more efficient than running is, requiring less oxygen. StuRat (talk) 22:22, 8 May 2015 (UTC)[reply]

I had thought of that, but consider that whales need to do that without constant access to new air. They get a gulp of air, and then that's all they have for awhile while swimming. --OuroborosCobra (talk) 22:33, 8 May 2015 (UTC)[reply]

• This thesis is the subject of the book Out of Thin Air. μηδείς (talk) 22:18, 7 May 2015 (UTC)[reply]

Thanks for the responses. I knew that the oxygen level must change some and I know it changes over long periods. But it seems to be remarkably close to being constant, i.e. very well balanced. Bubba73 ^{You talkin' to me?} 23:05, 7 May 2015 (UTC)[reply]

Why, in some places, the weather is so stable year-round, whereas in other places, the temperature can drop and rise extremely, leaving little room for comfortable and cool temperatures? What are all the variables that may influence the temperature at a specific location? Distance from the equator, amount of sunlight, number of clouds, water bodies, mountains, global climate change, etc.? 164.107.182.34 (talk) 18:17, 7 May 2015 (UTC)[reply]

The largest factors are latitude, with locations farther from the equator being more variable (both seasonally and daily), and distance from large bodies of water (especially oceans) due to the moderating effects of water's large thermal inertia. On a day-to-day basis, the presence or absence of cloud cover can make a big difference. Winter months tend to have more variability than summer months, and this is especially true is areas with sporadic snow cover. Dragons flight (talk) 18:35, 7 May 2015 (UTC)[reply]

Agree, but note that bodies of water lose their moderating effect when completely covered with ice. At that point, they behave like land, as far as the weather is concerned. Thus polar regions can hit extremely low temperatures, even small islands in the middle of the Arctic ocean. StuRat (talk) 20:11, 7 May 2015 (UTC)[reply]

The OP would be well served to start with an article like Climate and then follow links from there. The broad, average weather trends for a specific location is called "climate", so looking in to what causes the climate of an area will lead to understanding the issue. A common scheme is the Köppen climate classification system, and our article (and articles on the specific Köppen climate types) go into some considerable detail which should answer the OP's question. --Jayron32 18:57, 7 May 2015 (UTC)[reply]

The centripetal force is the force orthogonal to the circular pathway, pointing at the center. Driving on a highway or riding on a roller coaster, you may feel a force that pushes you in the opposite direction of the vehicle movement. What is that force called? Or perhaps, you are feeling the force that pushes you in the linear direction, tangent to the "circle", but the circular pathway forces you to go in the circular motion instead of flying out of the circular motion? Is there a reason why the circular highway roads often have a set diameter, given the average speed limit of the road? 164.107.182.34 (talk) 20:16, 7 May 2015 (UTC)[reply]

The apparent (sometimes labelled "fictitious") outwards force is called centrifugal force. For any given radius, there is a maximum speed at which it is possible to follow the circular road without skidding, but this speed depends on the road surface and the tyres. A tangential force is felt when the speed is changing. Here in the UK, the radius of the circle varies, but when expected speeds are higher the radius is greater so that skidding is less likely. The frictional force at the tyres needed to keep a vehicle going round in a circle is proportional to the square of the speed, and inversely proportional to the radius. See the article on circular motion for details. Dbfirs 20:32, 7 May 2015 (UTC)[reply]

Centrifugal force is labeled a fictitious force because it is one. Another synonym for "fictitious force" is "inertial force." I think the OP's question is probably better understood in terms of momentum and inertia, and Newton's first law. The units are different from force. When you feel "pushed to the left" as your car turns to the right, there is no actual force pushing you to the left. That's why centrifugal force is a fictitious force. Rather, the car is supplying a centripetal force to you and you only feel pushed to the left because of your frame of reference in the car, and your inertia. I'm just trying to explain the same thing you are, but with slightly different words. I'm not sure, but I don't think the fictitious force of centrifugal force is even taught that often in high school and non-major physics at the undergraduate level any more. Most courses that I'm familiar with stick to centripetal force and inertia/momentum. SemanticMantis (talk) 20:46, 7 May 2015 (UTC)[reply]

Yes you are correct that it isn't taught (for good reasons). I mentioned the word "centrifugal" only because the OP asked for the word, so I linked to our article. In my teaching, I never mentioned either "centrifugal" or "centripetal" except to warn about mis-use. Were I inclined to totalitarianism, I would ban the words because of widespread misunderstanding, but I do occasionally use the concept of centrifugal force in my own thinking as a shortcut to an answer within a limited rotating frame. Dbfirs 21:36, 7 May 2015 (UTC)[reply]

There is nothing fictitous about the force. If you hold a rope in each hand and a giant whirls you around his head via the end of one rope, and a large rock is attached to the outboard end of the other Giant----You----Rock , the force you feel in your left hand, say inboard, is no more or less fictitious than the force in your right hand, yet one is towards the centre (centripetal), and one is towards the outside, centrifugal. Calling it fictitious doesn't make it go away. Now, I'd entirely agree most times it is easier to write the equations in an inertial reference frame, but that is not the point.Greglocock (talk) 23:27, 7 May 2015 (UTC)[reply]

I just call it the tension in the rope, and, as you say, that is indeed real. Calling it "centrifugal force" tends to lead to misunderstandings by those who don't fully appreciate the difference between an inertial frame and a rotating frame of reference. Dbfirs 07:06, 8 May 2015 (UTC)[reply]

Actually, it's easier to write the Newtonian force equation (F = m·a) in the non-inertial reference frame - specifically the one whose rotation exactly matches the object that's spinning. That's the frame where the force looks like a constant and you can solve for the equation of motion very simply! If you write the equations in an inertial reference frame, the force (its direction and magnitude) vary with time.

The tricky parts really come in to play because you can't write all of the forces in the same reference frame. If you were spinning a bucket, and you considered the rotating reference frame inside the bucket, you'd have to consider that the force of gravity varies with time (i.e. because the bucket's orientation is changing as it spins).

Physicists who have to deal with this problem simply avoid it. After spending a few years of Newtonian mechanics, physicists learn to write equations of motion in terms of energy instead of in terms of force. This is the translation to an equivalent formulation of dynamics: Lagrangian mechanics, Hamiltonian mechanics, or Jacobian mechanics (and so on). In these treatments, we don't care what's rotating or what force it feels: instead, we simply consider how systems will evolve, and what trajectories objects will take, when subject to potential energy systems and external constraints. The accelerations that these objects feel are produced as outputs of the calculations. This makes simple work out of the analysis of non-rigid bodies, rotating (or otherwise transformed) reference frames, and so on. It is how we model vehicle dynamics, robot movement, and complex systems. A classical application: how much torque must be supplied by the motor at robot's wrist, when the robot arm's shoulder-joint is rotating? ... And if the robot arm has six shoulder-joints, each one also moving? If you try to solve that using Newtonian mechanics and a rotating reference frame, you'll give up in a hurry and seek out one of these other analytical methods! Instead, we use mathematical representations of the kinematics that are more suitable for fast calculation, and that account for real effects ("fictitious" or otherwise).

Nimur (talk) 16:13, 8 May 2015 (UTC)[reply]

What makes a roller coaster exciting? Is it the gravitational force that pulls the coaster straight down, creating the allusion of a freefall? Would a roller coaster be just as exciting in a gravity-free environment, like in space? 164.107.182.34 (talk) 20:47, 7 May 2015 (UTC)[reply]

It is difficult to predict, given that different experiences are involved. I think that the built-up of dread before a massive descent would no longer occur, because there is no descent. All there are in place of descents are rapid changes in curvature. However, the ride would be very disorientating on account of there being no up or down. That in itself could lend a factor of excitement. There's no way to tell whether the tradeoffs are of equal value or not, without a trial and error. Plasmic Physics (talk) 21:20, 7 May 2015 (UTC)[reply]

Note that a roller coaster, by definition, requires gravity. That is, it's lifted using power, then it's dropped and gravity does the rest. You could power the entire length of the ride, or rely on inertia to finish the trip, but that would result in a gradually slowing ride. Perhaps if you put enough (powered) acceleration at the start, that might make up for the lack of a "drop" in the middle.

If your space station already has a (human-sized) centrifuge, for health reasons, perhaps you could make that into a virtual roller-coaster, with the aid of some VR goggles, to match the view with the changing g-forces. StuRat (talk) 21:28, 7 May 2015 (UTC)[reply]

• Going to space to ride a rollercoaster is like going to Paris to check out their McDonald's restaurants. I am not sure that a roller coaster requires gravity by definition, as what it requires is acceleration, and the changes in velocity caused by the deflection of a track (or a track substitute). Theoretically that's easy to design.

μηδείς (talk) 22:04, 7 May 2015 (UTC)[reply]

Everything has an evolutionary meaning, make-up included. "Darwin states that any deliberate mate selection is of women by men, not the other way around. Therefore, it is female features that are important in mating success, such as beauty, red lips, shapely breasts, as well as artificial means such as jewellery and make up."... The question is, are females aware that their make-up is a tool for attracting males? --Mr.Pseudo ^{Don't talk to me} 22:00, 7 May 2015 (UTC)[reply]

Yes. StuRat (talk) 22:04, 7 May 2015 (UTC)[reply]

You could try asking some. Top tip: adult females of the human species are referred to as 'women'. AlexTiefling (talk) 22:07, 7 May 2015 (UTC)[reply]

No concern for the poor adult human males? μηδείς (talk) 22:14, 7 May 2015 (UTC)[reply]

Oh, good point. Yeah, it's not cool to talk about men like they're specimens in a nature documentary either. AlexTiefling (talk) 22:54, 7 May 2015 (UTC)[reply]

Enough people behave as animals in this regard, yielding to instinct with little concern for the impact upon dignity or self-worth. Plasmic Physics (talk) 23:01, 7 May 2015 (UTC)[reply]

• Sexual selection applies both ways, it explains the showy colors of male songbirds such as the Fairy Wrens and the Cardinal and human penis size. The quoted source is not the best, I'd just read sexual selection. As for humans, being sapient, the answer, as noted, is yes. μηδείς (talk) 22:14, 7 May 2015 (UTC)[reply]

I agree that the cited source is no good. The quote is simply not true. I call ^{[citation needed]} on the claim that Darwin said any such thing. SemanticMantis (talk) 22:45, 7 May 2015 (UTC)[reply]

• If one really wants to understand human behavior from an objective point of view (that is, viewing humans as animals), the landmark work in this vein is Desmond Morris's The Naked Ape; besides the original book there have been several adaptations for film and for television. Morris is the sine qua non of this field of study. --Jayron32 02:11, 8 May 2015 (UTC)[reply]

"[...] serialized in the Daily Mirror [...] explanations failed to convince many academics [...] starring Johnny Crawford and Victoria Principal [...]" Why would you recommend this? -- BenRG (talk) 05:01, 8 May 2015 (UTC)[reply]

Desmond Morris's standing among academics has little to do with whether his theories are correct or not. In talking about him with my anthropology profs, it seems that a lot of his work is dismissed out of hand because of his apparent focus on treating people as animals (vis a vis his background in zoology). As a "celebrity" he also suffered from the kind of excessive scrutiny guys like Stephen Jay Gould and even Carl Sagan had to deal with. For example, now that he's safely dead, Sagan can get all kinds of posthumous recognition, but alive he was denied membership in the NAS. Personally, I doubt we'll get a proper handle on Morris's methods and conclusions until after he's gone as well. Matt Deres (talk) 13:33, 9 May 2015 (UTC)[reply]

The Descent of Man is in the public domain and you can read it for free online. That page does seem to misrepresent what he said. The closest I can find in the book is "Man is more powerful in body and mind than woman, and in the savage state he keeps her in a far more abject state of bondage than does the male of any other animal; therefore it is not surprising that he should have gained the power of selection. Women are everywhere conscious of the value of their own beauty; and when they have the means, they take more delight in decorating themselves with all sorts of ornaments than do men." But then he goes on to list examples of savage women having some choice of their mates and says "We thus see that with savages the women are not in quite so abject a state in relation to marriage as has often been supposed." And he seems to think the civilized races are quite different, saying "Civilised men are largely attracted by the mental charms of women, by their wealth, and especially by their social position; for men rarely marry into a much lower rank. [...] With respect to the opposite form of selection, namely, of the more attractive men by the women, although in civilised nations women have free or almost free choice, which is not the case with barbarous races, yet their choice is largely influenced by the social position and wealth of the men [...]." The only mention I noticed of shapely breasts is a statement that Northern American Indians are especially attracted to "breasts hanging down to the belt", as one of many examples of differences in standards of beauty between different races. There are also amusing passages like "The resemblance of Pithecia satanas with his jet black skin, white rolling eyeballs, and hair parted on the top of the head, to a negro in miniature, is almost ludicrous." So maybe you should not take what Darwin says as gospel. -- BenRG (talk) 05:01, 8 May 2015 (UTC)[reply]

Can anybody recommend a glue that will bond plastic to metal. I'm currently building a model but it came through ebay and is missing the screws required. --Andrew 19:27, 8 May 2015 (UTC)[reply]

This resource [8] has recommendations for bonding many substances to other substances. In this case they recommend J-B Weld, or "LePage's Metal Epoxy" - additional info on these products, and reasons for recommendation are available at the site. SemanticMantis (talk) 19:34, 8 May 2015 (UTC)[reply]

Have you looked for the required screws ? I should think if you took it to a good hardware store they could try out various screws until they find a match. Note that screws generally have far more holding power than adhesives, unless a very large area of adhesive is applied. Some screws are also removable, in case you need to do maintenance on the item. StuRat (talk) 00:58, 9 May 2015 (UTC)[reply]

Some cyanoacrylates will work, if the parts mate smoothly. Don't use too much.    → Michael J Ⓣ Ⓒ Ⓜ 02:33, 9 May 2015 (UTC)[reply]

Use two component epoxy. Ensure the metal parts are not too smooth. Degrease before applying the epoxy. Degrease metal parts with brake cleaner. Do not touch surface to be glued after degreasing. Note, how to handle this products! False use is dangerours. Small amounts are expensive, applications for fiberglass may have better pices. --Hans Haase (有问题吗) 09:12, 10 May 2015 (UTC)[reply]

There are several problems with using glue where the model was designed to use screws:

1. The glue (especially the kinds that work with metals) takes up space. So you'll never be able to get the parts to fit together as accurately as they should.
2. Screws not only hold the thing together, they also force a very specific and precise alignment of the parts together that you may find difficult to get right with glue.
3. Screws can generally provide more strength than glue...not always...but in the case of plastic-to-metal, I'd be quite surprised to find a glue that was anywhere near as strong.

Inaccurate fitting may make it much harder (or perhaps even impossible) to put the rest of the kit together - so these are not minor issues.

Since you're likely to need to take a trip to the hardware store to get the rather specialised glue that you need - why not just buy screws instead - it's actually likely to be cheaper. SteveBaker (talk) 15:21, 10 May 2015 (UTC)[reply]

Is Dark Matter death? ? asked by Ed Slater artist from Dumfries

No. --OuroborosCobra (talk) 00:27, 9 May 2015 (UTC)[reply]

Says it all, really. Death is a process, whereas dark matter, if it exists, is a substance, so the OP's question can be answered in the negative on purely metaphysical grounds. You can have a bottle of dark matter (how large it would be and what the walls would be made of is another question), but you can't have a bottle of Death. Tevildo (talk) 09:34, 9 May 2015 (UTC)[reply]

Duncan MacDougall (doctor) tried to measure a loss of weight from patients/corpses at the moment of death (see also [9]), claiming positive results. If this were taken at face value it might back up a death-based mechanism of dark matter production. However, it's been nearly a century since this was even a sci-fi grade reference, since it is universally assumed that the small sample size and measurement error were to blame. Wnt (talk) 11:34, 9 May 2015 (UTC)[reply]

• You can't have a bottle of death, but you can have a charred hunk of evil. (Tevildo's point is actually quite important, and you'll find a lot of the motivation behind drug and gun control legislation is the ideas that those things themselves are evil, not how they are misused.) μηδείς (talk) 18:30, 9 May 2015 (UTC)[reply]

I dunno. It's not death as depicted by the Grim Reaper or "souls" as seems to be implied above. However if it's the result of universe expansion and cooling, it could very well represent the death of the stars, galaxies and universe. I suspect there is a volume and temperature that no longer supports stellar formation or any type of coalescence. "Assumed room temperature" may be quite apt description of "death" and if the universe assumes the temperature of dark matter.... --DHeyward (talk) 05:48, 10 May 2015 (UTC)[reply]

This is the science death desk, however, not the metaphorical death desk. μηδείς (talk) 14:48, 10 May 2015 (UTC)[reply]

Hi there!
What are the symbols of this formula meaning in the context of the space elevator: dF = (GMρA/r² − ρAv²/r)dr ?
Thank you for your answer!
Calviin 19 (talk) 10:06, 9 May 2015 (UTC)[reply]

F is the force on a particular point in the cable exerted on it by the cable below it (which is calculated by integrating the above formula), G is the Gravitational constant, M the Earth's mass, ρ the density of the cable, A the cross-section area of the cable, v the orbital velocity of any part of the cable and r the distance from the Earth's center. - Lindert (talk) 10:30, 9 May 2015 (UTC)[reply]

[ec] The equation appears in this paper by Jerome Pearson, where the symbols are explained thus:

G is the gravitational constant

M is the mass of the Earth

ρ is the density of the tower and A is its cross-sectional area

v is the velocity at point r on the tower due to the Earth’s rotation.

It's not explicitly stated in the paper, but dF is the increase in the (vertical) force on the tower for an increase dr in height. Lindert's posting above agrees with Pearson's definitions. Tevildo (talk) 10:37, 9 May 2015 (UTC)[reply]

Considering we have not yet found a viable alternative to oil and gas, is it possible that commercial passenger planes could become extinct by the end of this century? 92.25.95.41 (talk) 10:49, 9 May 2015 (UTC)[reply]

I doubt it. I web searched natural gas powered plane and came up with [10]; you can repeat for the fuel source of your choice. (In the 50s they even considered nuclear airplanes!) Now powering a plane with heavy, high pressure tanks of combustible gas doesn't sound like the most appealing idea, but people do what they have to. Also see [11] (I think we had a thread on that recently) Wnt (talk) 11:39, 9 May 2015 (UTC)[reply]

The weight might be an issue, but as for flammability, the current jet fuel is somewhat flammable, too. Synthetic jet fuel would be the logical replacement. Since it's considerably more expensive, you could expect air travel to reduce, but not end. StuRat (talk) 11:42, 9 May 2015 (UTC)[reply]

There are many alternatives, both old and new. Just as we had electrical cars in the 19th century, we also had Rigid_airships crossing the atlantic way back. Hydrogen-powered_aircraft is one of many newer alternatives. Star Lord - 星王 (talk) 13:13, 9 May 2015 (UTC)[reply]

Lighter-than-air travel is inherently dangerous, as winds can easily blow the ship off course, make mooring impossible, etc. It's also inherently slow. You might think it would at least be peaceful, but those steering props still cause noise and vibration. I should think travel by ship or train would be better alternatives, should planes somehow become impractical. StuRat (talk) 13:24, 9 May 2015 (UTC)[reply]

I'm still holding out for a magic carpet myself - a giant membrane, light as parachute cloth, covering a vast area, with actuators to wiggle it up and down in wave patterns and/or open and close pores in the material, with some kind of howdah in the middle and (of course) exquisite computer modelling to guide it. Wnt (talk) 16:11, 9 May 2015 (UTC)[reply]

I wouldn't write off airships just yet [12] [13] although they're being developed for cargo rather than passenger transport. Richerman (talk) 16:46, 9 May 2015 (UTC)[reply]

Yea, with some types of cargo scheduling is less critical, so intermittent, slow deliveries might be acceptable. StuRat (talk) 17:49, 9 May 2015 (UTC)[reply]

I added to the title to give a clue what the Q is about. StuRat (talk) 13:19, 9 May 2015 (UTC)[reply]

Wikipedia is not a crystal ball. Come back in 80 years and we will delighted to give an answer about fin-de-sicle plane fuel. --Llaanngg (talk) 17:51, 9 May 2015 (UTC)[reply]

Not likely. Unless batteries with comparable energy density to fuel can be developed, hydrogen or biofuels are the most likely option. Mr.Z-man 23:23, 9 May 2015 (UTC)[reply]

No. Oil and gas will be around much longer than the end of this century. Of course, a hundred years ago, if you phrased the question using steam trains and coal: steam trains are all but gone as are trains that run on burning coal directly - nothing to do with supply though. Quite possible that suborbital ballistic transport using rail guns or other technology is available. In that sense, we're not a crystal ball but there's no reason to think it will be limited by supply of oil or gas. --DHeyward (talk) 06:21, 10 May 2015 (UTC)[reply]

completely extinct? Almost certainly not. Even in a worst case scenario, enough fuel could be synthesized that the elite could still get where they wanted to go.

Could fuel become scarce enough that middle-class luxury travel goes extinct? Sure. But for the majority of the world's population, airfare is out of reach anyway., so we don't have to work too hard to imagine what that would be like. 75.69.10.209 (talk) 18:28, 10 May 2015 (UTC)[reply]

We learned that the adipose tissue has the smallest amount of extracellular matrix. What does it mean? 149.78.38.232 (talk) 11:42, 9 May 2015 (UTC)[reply]

Adipose tissue, Extracellular matrix. Bus stop (talk) 13:34, 9 May 2015 (UTC)[reply]

To put it in context, consider liposuction. It works well enough (though it strikes me as kind of a brutal procedure). But it wouldn't work with a bone, or even most internal organs (though that's kind of hard to evaluate because if you want to remove those usually you need to get every last cell and deal with a much larger blood supply). Adipocytes are huge cells without much structure, separated by narrow gaps, and adipose tissue tends to fit into various spaces whichever way pressure dictates. Wnt (talk) 16:17, 9 May 2015 (UTC)[reply]

Is it simply because of the lack of physical barriers obstructing the wind? Malamockq (talk) 13:39, 9 May 2015 (UTC)[reply]

This link gives the math to explain it. >http://www.google.co.uk/url?q=http://www.iawe.org/Proceedings/7APCWE/T2D_5.pdf&sa=U&ei=mB5OVdrFIMLQswHi7oDADw&ved=0CBYQFjAA&usg=AFQjCNEw46UhkdHaqUXR0eOTB20-UPZ9rA< Topographical effects on wind speed over various terrains.--Aspro (talk) 15:05, 9 May 2015 (UTC)[reply]

A more direct version of that link: http://www.iawe.org/Proceedings/7APCWE/T2D_5.pdf —Tamfang (talk) 19:07, 10 May 2015 (UTC)[reply]

Yes. Trees or even plants slow wind considerably, and hills and mountains even moreso. Completely flat ground with no vegetation, like salt flats, might not. And note that the wind speed difference between land and sea fades with altitude. StuRat (talk) 15:07, 9 May 2015 (UTC)[reply]

There's a piece missing as there is off-shore winds that are largely unaffected by the coast and are larger over oceans because of lack of topographical interaction. But there is also diurnal winds (i.e. Sea breeze or on-shore winds) that are caused by the difference in air pressure driven by heat capacity differences of land and sea. It's windier at the beach - both on water near the beach and on shore - because the land heats and cools daily while the ocean temps is relatively constant throughout. --DHeyward (talk) 06:55, 10 May 2015 (UTC)[reply]

What's the distance between a natural science, and it's engineering or applied version? Think: chemistry and chemistry engineering, or biology and biotechnology. Is it common to find someone with a pure science background competing against someone with an applied science background? --Llaanngg (talk) 17:59, 9 May 2015 (UTC)[reply]

"Applied", meaning using something for a purpose? Maybe see basic science vs applied science or science vs engineering or chemistry vs chemical engineering? There's a lot of overlap, where people working on basic science are still aiming to solve an applied problem (very common, especially to have a "so what good is this new thing?" answer for purposes of getting grants and publications), or working in applied science and still developing new basic science along the way. DMacks (talk) 19:28, 9 May 2015 (UTC)[reply]

I don't think it makes sense to put a hard division between theoretical and applied sciences...or between the people who work in them. To pick a well known counter-example: Albert Einstein - probably considered to exist at the extreme theoretical end of the scale of scientific achievement - famously designed the Einstein refrigerator and a hearing aid...both being examples of practical consumer product engineering at the very opposite end of the scale. Is this common? It's a matter of degree - so I don't think it's possible to nail it down. SteveBaker (talk) 20:10, 9 May 2015 (UTC)[reply]

• An example: the applied version of biology, chemistry, and in some degree physics, is medicine. --Mr.Pseudo ^{Don't talk to me} 20:13, 9 May 2015 (UTC)[reply]

There is often not a clear distinction. If you look at the articles in the Journal of Applied Physics for instance, it can be difficult to imagine a real "application" for all of them. Is the sound velocity of tantalum under shock compression in the 18–142 GPa range really of any industrial interest? Probably not, or else it would be published in a more engineering-focused journal. Research published in something like the Journal of Constructional Steel Research is certainly going to be on the "applied" part of the spectrum, while Low Temperature Physics is more "pure." But most research published is more toward the middle of the spectrum, not "science for the sake of science" but still several degrees removed from any real-world application. Mr.Z-man 23:16, 9 May 2015 (UTC)[reply]

You mention chemistry/chemistry engineering and biology/biotech. The way you describe things as "pure" vs "applied", and using the word "compete", I am here assuming you mean lab chemistry and chemical engineering. All have been in labs, but chemical engineers are also trained to put together the industrial side: pipes, valves, pumps, tanks and other chemical machines. There is not a lot of "competition" here. Nor is there much competition between biology and biotechnology. In biotech fields where the science is well known and scalability is a factor, it is often built by chemical engineers. Biologists are usually more interested in animals or plants than any tech. The "purest" forms of chemistry is in my experience performed by physicists and mathematicians. There is overlap among all, but I see a lot more cooperation than competition. There is definitely no general "distance" between "pure" and "applied" in science. Most uses of the word "applied" that I have seen have been for marketing purposes rather than any strict division between them. Star Lord - 星王 (talk) 23:21, 9 May 2015 (UTC)[reply]

I've known a couple of people who did maths at university that worked as, or at least, alongside, engineers. I've also known at least one who did pphysics and several who did materials science working as engineers. Greglocock (talk) 00:17, 10 May 2015 (UTC)[reply]

Let's say you're of average build, not with a body built for it like Eskimos. You could have gigantic downy outer shoes and un-stiff enough clothing inches thick and huge mittens over gloves but I imagine that eventually your eye holes will hurt. So you'd need goggles but if it'd take so many nose-less balaclava layers that it'd be uncomfortable to breathe and so you'd need added oxygen and near airtightness and two helmets and a personal heater like an astronaut and that's when it stops being clothing anymore and more like a spacesuit. If it would require a wind too strong to not tumble in then then I guess that for all practical purposes it never gets cold enough because you physically couldn't go out without bouncing downwind for miles. There should be two answers to this, one with traditional clothing materials and one with all the stuff that modern technology can manage like all those Uniqlo-type thin products or mirror coating on all skin touching surfaces or whatever. — Preceding unsigned comment added by 128.177.161.150 (talk) 10:57, 10 May 2015 (UTC)[reply]

The short answer to the question exactly as posed is probably "yes, the inside of a Swedish sauna or Turkish bath". However, assuming the questioner specifically has cold environments in mind, the answer would appear to be the colder parts of Antarctica. See, for example, Ranulph Fiennes' reports of his expeditions. RomanSpa (talk) 12:04, 10 May 2015 (UTC)[reply]

The lowest temperature recorded at Vostok Station in the Antarctic winter is -89.2°C, colder than dry ice, so very likely to be "uncomfortable" even with actively-heated clothing. Tevildo (talk) 12:11, 10 May 2015 (UTC)[reply]

You can use the Coldavenger face mask, which moistens the air you breath in using the moist in the breath you exhale.Count Iblis (talk) 16:28, 10 May 2015 (UTC)[reply]

As in stillsuit? μηδείς (talk) 20:51, 10 May 2015 (UTC)[reply]