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December 27

Reducing the fever by drugs doesn't harm the body?

In general, When people have a fever, it indicates that they have an inflammation of pathogenic microbes. That the natural way of the body to kill them. My question is When people take drugs that reduces the fever, doesn't it disturb the body to make its work and to kill the pathogenic microbes? 213.57.97.151 (talk) 05:52, 27 December 2014 (UTC)[reply]

I believe the fever to be a side effect of a massive cellular level war between the body's immune system and the infection, and a high enough fever will start to damage organs, so keeping body temperature low is important. StuRat (talk) 06:43, 27 December 2014 (UTC)[reply]

Do you think that any fever can damage the organs? there are many levels of fever. 213.57.97.151 (talk) 07:32, 27 December 2014 (UTC)[reply]

No, not any fever, a "a high enough fever", as I said. StuRat (talk) 20:27, 27 December 2014 (UTC)[reply]

I am no doctor and have no idea about medicine, but once I asked the very same question and what I gathered from the answers is that (in my (uninformed) opinion) we still do a lot of things in medicine without really having a solid understanding of what's going on. --Schweinchen (talk) 09:37, 27 December 2014 (UTC)[reply]

Since no-one has linked to it, yet, I'll just mention that we do have an article on Fever that mentions differing views, and that damage doesn't occur below 107 degrees F. Dbfirs 09:53, 27 December 2014 (UTC)[reply]

I didn't see any reference for the my question in our article fever.213.57.97.151 (talk) 12:41, 27 December 2014 (UTC)[reply]

There are some referenced studies in the section Fever#Usefulness. Dbfirs 13:33, 27 December 2014 (UTC)[reply]

The problem with high fevers is that they denature the bodies proteins, causing brain damage first and then general organ failure. This should all be in the fever article. μηδείς (talk) 18:45, 27 December 2014 (UTC)[reply]

I would say there is a general problem with meds designed to get you "back to work quickly" by masking symptoms, when you probably should be home recuperating and not at work infecting others. Fever is just one of the symptoms. StuRat (talk) 20:29, 27 December 2014 (UTC)[reply]

Self driving trains

Why don't all trains just become self driving? The technology is there so is it just cost? — Preceding unsigned comment added by 94.14.212.193 (talk) 14:00, 27 December 2014 (UTC)[reply]

In some cases it's a matter of influential train-driver unions, in others, the public perception of safety. Many operators of self-driving trains prefer to have a competent human on board to deal with breakdowns and emergencies, even when he or she is not actually "driving". Dbfirs 14:38, 27 December 2014 (UTC)[reply]

I spent a small slice of my career designing simulators too teach train drivers' their job - and I went into it thinking "Just how hard can this be? After all, it's not like a car where you have to steer - or even decide where to go - it's just a throttle and a brake!" So I set about learning what it takes to drive a train - and I came out of it realizing that this can be an incredibly difficult job. In the USA, train drivers get paid more than airline pilots - and that's not because they have a better union. There is an immense amount of subtlety to driving a 2 mile long coal train with seven locomotives in mountainous terrain with poor traction and tight winding curves in some areas - they are also responsible for checking and reporting on track defects, broken signals, missing signs...you name it. It's also a very stressful job. I came out of the learning curve with great respect for the difficulty of driving a train. It's interesting to note that the reasons that Burlington-Northern wanted us to build them simulators was not so much to teach people to drive trains - but to train them to minimize fuel usage, which is a huge deal for the company. I forget the exact numbers - but the difference in fuel cost between their best driver and an average driver by far exceeded the salary they paid a train driver - so getting good people was absolutely paramount to their operations.

The easiest type of vehicle to automate is an aircraft (so it's no surprise that we have wildly successful drones out there) - and we know that the biggest problem with airline pilots is surviving the boredom and inactivity because the plane pretty much flies itself already. Since I've also spent years working on flight simulators - I can definitely say that flying a modern airliner is a hell of a lot easier than driving a freight train. That's surprising because aircraft have an insane number of controls, and a vast number of instruments to monitor - where a train has very few of either.

I doubt that the public would have much of a problem with robotic freight trains - but I suspect that the big issues (as with driverless cars) would come when they'd have to give up the feeling of security that comes from having a person at the controls of a passenger train...despite the fact that human error dwarfs all other causes of accidents - in the air on tarmac or on rails.

SteveBaker (talk) 16:11, 27 December 2014 (UTC)[reply]

With the ongoing fear of cyberwar with North Korea, I would emphatically not want to trust a robot freight train loaded with dangerous cargo. For that matter, I wouldn't feel all that safe about some junior railman who believes every speed limit the computer has listed for the track. (And I suppose the hackers can figure out which ones are junior easily enough...) Wnt (talk) 17:19, 27 December 2014 (UTC)[reply]

Public perception of safety is obviously an issue. However this will also depend on local issues and other factors. Let's not forget as the OP said and shown by Dbfirs link, driverless trains are a reality and have been for a relatively long time now with many millions transported every day. I rode on one circa 1999-2001, and IIRC this didn't have any staff on the train or many platforms (was monitored by CCTV). OTOH, AFAIK and our article also suggests these are nearly universally urban lines metro/rapid transit sort of thing generally with dedicated lines with right of way, no mountainous terrain or difficult curves, electric locomotives, communication systems and stuff set up for the purpose, etc. Long distance self driving trains don't seem common if they even exist in commercial operation. [1] actually claims the Rio Tinto line in Australia (mentioned in our article) will be the "first automated, long distance, heavy haul rail network", although that still allows a long distance non heavy haul network and I'm not sure the length of the line and think it's also dedicated. (One advantage to driverless trains in urban systems which is less prominent in long distances systems is allowing all day high frequency operation without having an extremely high cost.) Nil Einne (talk) 17:45, 27 December 2014 (UTC)[reply]

I'd think the safest train would combine the best of a human operator, like flexibility, with the best of a computer, like consistency. For example, you could have a human operator, but one who must pass a breathalyzer test to turn on the engine, and who gets alarms if the computer detects any problems, including the operator's head dropping. Those alarms should also be reported back to the control center, so they know, for example, if one of their engineers needs a nap. StuRat (talk) 19:11, 27 December 2014 (UTC)[reply]

The visible "envelope" of atmosphere slightly beneath the aurora

I just saw a link to some really neat time lapse photography of auroras and other phenomena (though, alas, I see no indication of the time compression scale). [2] But I find myself focusing in on one single detail, namely, that the Earth seems surrounded by a sharply defined, well, what looks like a "cell membrane" - a visible 'top of the atmosphere' (though it isn't) which appears in the video at 0:55 and 1:07, for example. In the latter shot you can see it fade to a sharp rainbow line; in true darkness it is not visible and in bright light it is apparently swamped out, but at 5:25 it is lit with the glow of city lights. Now what's interesting at 1:07 and in the other aurora shots is that you can see it is separated by what looks like (on the computer screen!) a small gap from the base of the aurora. When I look at atmosphere of Earth it seems like auroras can be at a wide range of heights, yet with this gap there is a sense of a consistent organization. Which makes me wonder...

Is the "membrane" I'm seeing actually at a definable height, as opposed to receding if the spaceship went lower like a rainbow might?

Is the "membrane" always at the same height, or at one which can be predicted from simple parameters like time of day?

And if so... where is it?

And is the distance from it to the bottom of the aurora genuinely pretty constant?

And, of course... what layer of the atmosphere is it?

And is it produced by refraction or by ice crystals or ...?

Wnt (talk) 17:12, 27 December 2014 (UTC)[reply]

I'm not an expert in this field, but I would say that the boundary visible in the video is the tropopause. See, for example, File:Moon Limb & Troposphere.JPG, which shows the layers distinctly. It's visibile because it's an inversion layer - dust and other particles reach the top of the inversion, and are not carried any higher by convection currents. Tevildo (talk) 10:32, 29 December 2014 (UTC)[reply]

How detailed must a perfectly accurate brain model be?

Let's say we want to create a synthetic brain based on a real brain. To what level of detail would we need to model for the synthetic brain to behave indistinguishably from the real brain? Would we need to go down to the level of chemistry? Or even further than that, to subatomic particles where the uncertainty principle governs everything?--31.200.175.242 (talk) 17:43, 27 December 2014 (UTC)[reply]

Honestly I don't think anyone can answer this with confidence. Without even getting into "qualia", simply understanding basics of memory like long-term potentiation remains at a very primitive level of experimentation. It is one thing to replace the brain with a device, something else again to define when it is indistinguishable. Wnt (talk) 18:02, 27 December 2014 (UTC)[reply]

Neurons function using neurotransmitters and action potentials. The physical properties of the cells depend on the chemical structure of the fat, protein and other molecules and ions that make them up. Their behavior is electrochemical. As far as we know two brains that were identical at the molecular and chemical level down to charge distributions would be identical. There are some fanciful and rather materialistically naive theories of consciousness which treat it as a substance (e.g., eliminative materialism); and speculation based on fallacies, such as Penrose's The Emperor's New Mind that argue consciousness is weird and quantum mechanics is weird so the two must be intertwined. But there's no evidence of that beyond the fact that we know quantum mechanics is involved in the chemistry as such. There's no guarantee that two brains that were electrochemically identical (and in bodies) would both have the exact same conscious state, especially over time, but they would both be workable brains. μηδείς (talk) 18:38, 27 December 2014 (UTC)[reply]

(I have no relationship with OP.) This is a very high-quality response, Medeis, and I'm glad you made it, I appreciate it and was glad to read it.212.96.61.236 (talk) 22:23, 27 December 2014 (UTC)[reply]

I would have sent you a "thank" electronically, but evidently IP's can't get "thank"s so, I do so here in text. μηδείς (talk) 01:03, 28 December 2014 (UTC)[reply]

For that matter, though we quickly get into some truly theoretical and abstruse territory going down this path, it's entirely within the realm of possibility that two neural networks could give rise to identical states of consciousness even if they were constructed from radical different materials -- provided that the associations and responsive thresholds between all of the nodes (neurons) were identical. Many experts on theory of mind (both cognitive scientists and philosophers) have used this as a lens to try to deconstruct consciousness and the nature of reality as a mental construct through thought experiments exploring (for example) whether a completely digital simulation that replicated the firing of each and every neuron in a brain would in fact be the exact same entity as that which arose from the model brain itself. Basically an adaptation of the old brain in a vat argument that asks what would be the implications if it were not just the sensory stimuli that were simulated, but indeed the very physical processes of the brain itself.

Of course, it's worth dusting off that old chestnut that the brain has more individual associations between its neurons than there are atoms in the observable universe; when you view this question in that light, it's clear that the complexity of the task of actually creating an absolutely perfect replica brain are truly astronomical in scale and that it's very much a possibility that such a feat is simply outside the bounds of feasibility -- and possibly not just at present time, but indeed ever (it has been argued). Still, even as purely abstract inquiries that may never prove empirically verifiable, these thought experiments do provide us with some compelling (if sometimes seemingly counter-intuitive) insights into the interplay between concepts of consciousness and reality -- two manner of phenomena that to this day leave us largely just as perplexed as the classical philosophers, when it comes to establishing stable definitions. Anyway, getting back to the original point, with regard to the computational model of the mind, it's entirely possible (likely even) that the material medium is only relevant insofar as its physical properties shape the pattern of associations between the nodes which make up the neural net.

On a side note, while I absolutely agree with you that quantum phenomena have very little influence on the gross associations and patterns of a neural network like the human brain (and that such associations tend to be forwarded by those with little understanding of the levels of physical hierarchy involved), it should be noted that this lack of relevance may not necessarily and inevitably be the case for every kind of consciousness. Consider the implications of quantum computing -- bearing in mind the kinds of problems it is likely to be most useful in addressing, and how it would tackle them -- and it quickly becomes clear that we can't even begin to fathom the implications for consciousness as superpositions become a part of computational methods. Snow talk 08:21, 28 December 2014 (UTC)[reply]

It's kind of a tricky question. Lots of what goes on in the brain is undoubtedly noise, and once we have a thorough functional understanding of how the brain works — if that ever happens — we will probably be able to create radically simplified models that are more or less indistinguishable from it. The problem is that we currently have nothing approaching that level of understanding. In our current situation, the only way we could create a model indistinguishable from the brain would be to replicate it down to the level of individual molecules — not all molecules, but at least large molecules such as chemical receptors. Some people think it would be necessary to go down to the quantum level, but they are mainly physicists, and most neuroscientists don't buy their arguments. Looie496 (talk) 19:44, 27 December 2014 (UTC)[reply]

Yeah, that's crazy talk. Worrying about quantum entanglement and subnuclear particles and so forth is doing the X is spooky and Y is spooky so X and Y must be the same fallacy again. Consciousness obviously rises at an emergent level above the cellular level. Most current theories of the unity of consciousness have to deal with the timing of firing of cells. To simplify, if your red, round, fruity, crisp, mouth muscle, and so forth cells are all firing in harmony you will have the perception "I am eating an apple." See Hofstadter's I Am a Strange Loop and many other works. But quarks and such matter to consciousness in the same way the color you paint your house helps it deal with tornadoes. Since no phenomenon we know of or even suspect to exist has to do with nuclear decay we can safely ignore various aspects of nuclear physics and concentrate on biochemistry and higher levels of organization. μηδείς (talk) 22:53, 27 December 2014 (UTC)[reply]

What happens if you were absolutely balanced while deciding something without smooth gradation. And you must choose one. Would quantum noise decide for you? Sagittarian Milky Way (talk) 00:12, 28 December 2014 (UTC)[reply]

See Buridan's ass. I would say something like that has to be the case, although we're not going to have any empirical evidence to back it up given ethical and technological constraints. It's the reason why I said in my first post that an electrochemically identical brain (in a functional body) would be a working brain, but would not necessarily have the same conscious experience over time. In fact, chaos theory and common sense insist the two brains would rapidly diverge as experience accumulated. See this very recent article on real-time scanning and manipulation of brain cells. μηδείς (talk) 00:59, 28 December 2014 (UTC)[reply]

Tiles instead of continuous cover on Space Shuttles

Why Space Shuttles used tiles instead of continuous cover as heat insulation, which can't detach the way tiles could? Brandmeister^talk 19:51, 27 December 2014 (UTC)[reply]

I think the very fact that they could detach was desirable, so that tiles damaged during re-entry could easily be replaced. StuRat (talk) 20:11, 27 December 2014 (UTC)[reply]

This is an interesting question, and in fact our article Space Shuttle thermal protection system doesn't presently give the answer. What is clear enough is that many are made of LI-900, a material which is said [3] to be a sponge of silicon dioxide in 94% air, and which by all accounts is fragile - fragile enough to break by hand. There would seem therefore to be a major technical issue in trying to keep a single continuous layer, and if they have to have seams, why not break them at a preset pre-tested position, i.e. a tile boundary? But I haven't looked into this properly. Wnt (talk) 23:43, 27 December 2014 (UTC)[reply]

A continuous skin wouldn't allow for expansion and aerodynamic deflections of the structure in the way that tiles do - see the 'HIGH-TEMPERATURE REUSABLE SURFACE INSULATION TILES' section here: [4] AndyTheGrump (talk) 23:52, 27 December 2014 (UTC)[reply]

It is worth noting here (just in case anyone reading this gets the wrong impression) that detaching tiles had nothing to do with the 2003 Space Shuttle Columbia disaster, which was instead caused by foam insulation shed from the external tank,striking the leading edge of the port wing. -- ToE 00:21, 28 December 2014 (UTC)[reply]

Thanks. Brandmeister^talk 22:07, 28 December 2014 (UTC)[reply]

Cheeky/irreverent precious substance questions

If you dropped a perfect US handball-sized sphere of flawless diamond how would it bounce? (American handballs are only a bit over golf-sized, foreign ones are huge) What about other combinations of sizes 1 carat to Cullinan, surfaces, shapes, and drop heights? Same thing with gold. I'm guessing it has a dead cat bounce cause it's so soft but what about 14 karat or Sterling or pure silver or platinum or ruby, emerald, or pearls?

Two last questions. You can mark 24 karat gold without hurting your teeth - what substance could I chew to know how vigorously I could chew gold without it hurting? If the guinea nailed to the wood in Mutiny on the Bounty was real then gold is basically like yellow silly putty had children with steel. What do precious/noble metals and common jewelry alloys taste like? (Just licking them, no swallowing obviously). Maybe I should've licked my inherited gold while I still had it.. Sagittarian Milky Way (talk) 20:01, 27 December 2014 (UTC)[reply]

Suggest you lay off the egg nog for a while. Short Brigade Harvester Boris (talk) 20:06, 27 December 2014 (UTC)[reply]

To determine how well something will bounce, you need to list the surface it's dropped onto. For a very hard object, I'd expect very little bounce, unless dropped on an equally hard surface, like two billiard balls hitting each other.

And metals taste, well, metallic, although you are tasting the tarnish on them rather than the elemental metal. I'd expect gold and platinum to have very littler taste, since they don't tarnish. StuRat (talk) 20:09, 27 December 2014 (UTC)[reply]

I too thought that gold/Pt would either taste metallic if it had anything at all but didn't know if there were different flavors (like "taste copper not aluminum if you want to know what pure silver tastes like but don't have any"). Sagittarian Milky Way (talk) 20:28, 27 December 2014 (UTC)[reply]

Would any of linoleum, stone, ceramic, wood, metal, concrete or cement flooring, ice or common paving materials cause a bounce visible to the naked eye? I guess you could shoot small diamonds out of an airgun if the bigger ones would break at heights needed for bouncing but the small ones reach terminal velocity without breaking on impact. This is now one of the things I would do if I were a billionaire and no one knew the answer. Sagittarian Milky Way (talk) 20:54, 27 December 2014 (UTC)[reply]

Gold and silver are perfectly edible and used in Indian cuisine. --TammyMoet (talk) 22:04, 27 December 2014 (UTC)[reply]

Well harmless or not I'm not keen on swallowing metals. Sagittarian Milky Way (talk) 23:58, 27 December 2014 (UTC)[reply]

Swallowing metal is essential to life. AndyTheGrump (talk) 00:03, 28 December 2014 (UTC)[reply]

I don't know much about materials science, but come on, somebody has to actually try here. Elasticity (physics) is determined by things like Young's modulus and shear modulus, which for diamond are 1220 GPa^[5] and 553 GPa^[6] respectively. A pity I don't really understand whether that means the diamond starts to shear rather than deform when thrown at a wall. There is a paper on the elasticity of diamond at [7] which may also be helpful. Wnt (talk) 14:16, 28 December 2014 (UTC)[reply]

Reception of Einstein's ideas

Your typical internet crackpot will often claim that it doesn't matter whether people ridicule him. Einstein was also considered a joke, until he proved that he was right. And so goes the defense of an internet ground-breaking physics theory. But is it right at all that Einstein met lots of jest and disdain before he could prove them all wrong?--Noopolo (talk) 20:08, 27 December 2014 (UTC)[reply]

Probably the ones who thought he was nuts were ordinary people, with physicists taking him more seriously. There are a lot of things that can't be explained by Newtonian physics, and any physicist then would have been aware of this. StuRat (talk) 20:15, 27 December 2014 (UTC)[reply]

Not really - see Criticism of the theory of relativity. His ideas were disputed certainly, but not ridiculed by his scientific peers. AndyTheGrump (talk) 20:17, 27 December 2014 (UTC)[reply]

Special relativity was published in 1905, and the following year eminent physicist Max Planck gave a lecture promoting it. At that point there was no more proof of relativity than in the original paper, but the theory was considered very appealing by many at the time. The annus mirabilis papers, which were probably Einstein's first really ground breaking works, were all discussed in the physics community essentially immediately upon publication. Now, by no means did everyone agree. Luminiferous aether and other theories had serious supporters for many years after relativity was published, but Einstein's theories were undoubtedly taken seriously even by those who thought they were wrong. Dragons flight (talk) 20:36, 27 December 2014 (UTC)[reply]

When told of a book entitled "One Hundred Authors against Einstein", he replied "Why one hundred? If I were wrong, one would have been enough.". Greglocock (talk) 02:36, 28 December 2014 (UTC)[reply]

As I understand it, physics was a declining field of study as Newtonian and Maxwell had summed it up quite nicely except for a few loose ends. Einstein went after quantum effects first by earninf the Nobel prize for the photoelectric effect. He then moved toward relativity as quantum stuff made him a bit uneasy. Both are now cornerstone basis of modern physics. --DHeyward (talk) 09:24, 28 December 2014 (UTC)[reply]

We mustn't forget his paper on Brownian motion, which essentially proved the reality of atoms, something that was widely disputed at the time. Also the idea that physics was nearly complete was by no means universal. Those "loose ends" included the discovery by Becquerel, Thompson, and the Curies of radioactivity, which the physics of the time could not even begin to explain. This was a loose end of greater magnitude than the current problems with dark matter and dark energy. Looie496 (talk) 15:08, 28 December 2014 (UTC)[reply]

The 1933 pamphlet, Hundert Autoren gegen Einstein, is discussed at Criticism of the theory of relativity#A Hundred Authors Against Einstein, and I found images of the text (in the original German) here. Is the English translation available online? -- ToE 13:51, 29 December 2014 (UTC)[reply]

Why was any rocket ever painted?

Paint is heavy by rocket standards and just decoration. Sagittarian Milky Way (talk) 20:16, 27 December 2014 (UTC)[reply]

If paint was 'just decoration', you might be right. However, it also protects against corrosion for a start. The large Saturn V rockets were mostly white (probably to minimise heating due to sunlight), with contrasting black areas possibly to assist tracking. [8] AndyTheGrump (talk) 20:22, 27 December 2014 (UTC)[reply]

Well the orange Space Shuttle tank was painted white once but then was left bare cause it was a waste of lifting power. Weren't the Mercury rockets shiny metal? That addresses the issues you mentioned. Sagittarian Milky Way (talk) 21:03, 27 December 2014 (UTC)[reply]

'Shiny metal' (specifically the aluminium alloys most likely used) tends to corrode fairly quickly in coastal environments like Cape Kennedy, due to salt spray. AndyTheGrump (talk) 21:08, 27 December 2014 (UTC)[reply]

Oh, I didn't know that aluminum corroded on salt (I don't cook), I would've guessed it'd form a transparently thin layer of aluminum rust just like the shiny side of inland aluminum foil. Sagittarian Milky Way (talk) 21:21, 27 December 2014 (UTC)[reply]

If the rocket crashed, it might be useful to identify portions, especially if found years later, if it had a distinctive markings. StuRat (talk) 20:26, 27 December 2014 (UTC)[reply]

Well they could use shiny metal and paint just the markings, or even just anodize and roughen the metal to make markings. If that wasn't dark enough (I'm not familiar with ways to darken metal), a translucently thin paint coating could've been added to them. Sagittarian Milky Way (talk) 21:16, 27 December 2014 (UTC)[reply]

Zinc or strontium chromate-containing paints are commonly used to protect the metal surface ...-Dieter K. Huzel; David H. Huang (1992). Modern Engineering for Design of Liquid-Propellant Rocket Engines. AIAA. pp. 403–. ISBN 978-1-60086-400-1. -- Moxy (talk) 21:31, 27 December 2014 (UTC)[reply]

The V-2 rocket, the forefather of all modern space rockets, was painted with a large black and white check pattern "...to observe any variation or roll of the rocket. The exact pattern was changed many times, and as with the rest of the rocket, the pattern was examined and altered if warranted". [9] Alansplodge (talk) 22:19, 27 December 2014 (UTC)[reply]

Hand pain

I had cut the palm of my hand, it is now fully healed with no pain (and hence I'm not asking for medical advice). However, after it appeared to be fully healed, I still had the occasional sharp pain for a while. That's now ended, too, but I wonder why I continued to feel pain after the wound appeared to be fully healed. Were there nerve endings that still needed to heal at that time ? StuRat (talk) 20:23, 27 December 2014 (UTC)[reply]

This is fairly common. I had a cut in the heel of my hand almost 40 years ago and it still hurts occasionally. It was a deep cut and I assume it did damage to nerves or muscle. Short Brigade Harvester Boris (talk) 21:09, 27 December 2014 (UTC)[reply]

You probably have knife cancer, Stu. See a doctor. They do take x-rays to see if you've left a metal fragment or a chipped bone behind after the skin heals. . μηδείς (talk) 22:28, 27 December 2014(UTC

Have a look at this online gross anatomical drawing of the palm [10] Do you think your injury may have damage any connective tissue according to those drawing? See fascia. If so, your epidermis (the part of your palm that you can see) may have healed but there may have been scared tissue still present in the fascia – which is slower to heal. Read this quick, as although you state you are not asking for medical advice, there appears to be an acute outbreak on the Ref Desks of manic hatting.--Aspro (talk) 22:47, 27 December 2014 (UTC)[reply]

No one here is qualified to answer your question. If you're concerned, see a doctor. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:56, 27 December 2014 (UTC)[reply]

Rabbit inbreeding and genetic diseases

Do rabbits get many genetic diseases from all the in-family inbreeding? Gil_mo (talk) 21:37, 27 December 2014 (UTC)[reply]

undoubtedly they can, just on principle, but two factors mitigate against it mattering, they have many kits, and those with double recessive lethal genes simply won't develop or die at birth and so on. Second, many genetic diseases don't show up until adulthood or senescence, and most rabbits don't make it that far--that's why they need to breed like rabbits. See google on genetic diesase domesticated rabbit. μηδείς (talk) 22:35, 27 December 2014 (UTC)[reply]

Yea, inbreeding could lead to traits like buck teeth, a constantly twitching nose, and extremely long ears. :-) StuRat (talk) 01:11, 28 December 2014 (UTC) [reply]

Are you asking about domestic rabbits that are deliberately inbred by humans, or wild populations? If you haven't already done so, you should read our article inbreeding. In the wild there should be enough unrelated rabbits available so the some inbreeding is not really a problem for the overall population. Any system used by humans to produce inbred animals employs selective inbreeeding. Any animals with obvious defects are are weeded out and only the best quality ones are used for breeding stock. Of course, this is not completely effective as some defects can't be seen, and then inbreeding depression can become a problem. There are also other defects that can become apparent in groups of animals with a limited genetic pool, such as hip displasia and epilepsy in pedigree dogs. There is an interesting discussion about inbreeding in humans here, the principles of which also apply to animals. Richerman (talk) 11:40, 28 December 2014 (UTC)[reply]

December 28

Johann and Stefan Rausch Craniopagus Twins

Who are Johann and Stefan Rausch listed on this page https://en.wikipedia.org/wiki/Craniopagus_twins? The film Gifted Hands: The Ben Carson Story also refers to the Rausch twins. However, the film details the Rausch twins' surgery as 5 September 1987, the same day that Dr. Ben Carson separated Benjamin and Patrick Binder. Are Johann and Stefan Rausch the same as Patrick and Benjamin Binder, and if so, why do the twins have two sets of names? Thank you. DavidGStevens (talk) 01:11, 28 December 2014 (UTC)[reply]

Frost overnight on cars

Why is it that when a car frosts up over night, making it cold inside the car with air con makes the frost disappear faster? — Preceding unsigned comment added by 82.132.227.186 (talk) 09:31, 28 December 2014 (UTC)[reply]

Is it true? I find that lots of heat is necessary to get rid of frost. Perhaps you mean that the interior condensation from your breath is reduced when cold air is circulated? This would be because warm air can hold more water vapour, which means that more water condenses onto the cold windscreen. Dbfirs 09:44, 28 December 2014 (UTC)[reply]

Yes, recommended defrost setting is full fan, full heat, full a/c, full recirc. There's a couple of reasons. running full a/c and full heat dehumidifies the ventilating air, so preventing or reducing misting up on the inside of the windows. running full a/c puts more load on the engine, so it warms up faster, so the heater has more effect. Full recirc is used so that the heated air recirculates. However, once the car is reasonably warm it is a good idea to bleed off some of the cabin air as it will be quite humid. The specific recommendation will vary depending on the ambient conditions. This is a much less interesting question than I thought you'd ask - why does the windscreen of a car frost up sometimes overnight even if the surroundings don't? Greglocock (talk) 10:14, 28 December 2014 (UTC)[reply]

Because the windshield cools faster. I had an interesting case where I could see the frame of the hood through the hood, in the frost pattern, because those areas above the frame were kept warm longer and didn't frost up. It looked just like an X-ray. StuRat (talk) 15:57, 28 December 2014 (UTC)[reply]

( ... from evaporative cooling and radiative cooling, of course.) (This is a timely question here in the UK, because this is the first day this winter that my car windscreen has remained "totally opaque" with a thick white coating all day. I haven't driven it, of course.) Dbfirs 17:52, 28 December 2014 (UTC)[reply]

If there's frost on the car windows, at least you know there's moisture in the air. It's somewhat startling to emerge on a day where it's below 0 F. and find no frost on the windows. ←Baseball Bugs ^{What's up, Doc?} carrots→ 19:05, 28 December 2014 (UTC)[reply]

I once arrived at a customer's premises just a few minutes after bright early morning sunlight began shining on a frost covered lawn. Most of the frost had already melted, except where a tree had cast a perfect shadow. A frosty image of the tree, which was striking to see. Cullen³²⁸ Let's discuss it 19:14, 28 December 2014 (UTC)[reply]

Indeed. And with maybe just a word change or two, you've just written a little poem about it. :) ←Baseball Bugs ^{What's up, Doc?} carrots→ 19:31, 28 December 2014 (UTC)[reply]

late reproduction - quick evolution

Does reproduction at a later age lead to quick & better evolution? a giraffe, for example, lives for 25 years, attains sexual maturity at 4th year. Some million years ago, when their necks were not long as it is now, they'd passed their genes at the 4th year and continue to struggle eating leaves at the top of a tree for the rest of their years, it is during this time they are adapting/equipping themselves more. So, the genes when passes at this time would have a developed trait for offspring. When this is not the case, it takes a lot of time to accumulate the better quality to show up in offsprings. So, i ask is reproduction at a later age lead to quick evolution? -anandh, chennai — Preceding unsigned comment added by 122.164.133.100 (talk) 13:35, 28 December 2014 (UTC)[reply]

I'm not sure that I understand you correctly, but you seem to be asking if the offspring of a 25 year old giraffe have "better" genes and are better adapted to browsing from trees than those of a 4 year old giraffe? The answer to that is a firm no. The traits are passed to offspring by genes that as a rule don't change in a lifetime. Is that what you were asking? 13:48, 28 December 2014 (UTC)

(EC) It sounds to be like you're confused about modern evolutionary synthesis and various core parts like evolution, inheritance and genetics. Lamarckism is considered mostly wrong nowadays. Slightly more so than in the past, there is some acceptance of Lamarckism like inheritance via transgenerational epigenetics by some biologists, but even in that case, it's not normally considered anywhere are strong as you suggest and would probably not be considered to have anything to do with neck length in giraffes. Nil Einne (talk) 13:54, 28 December 2014 (UTC)[reply]

It sounds to me like the OP isn't that confused at all. During the period of time when animals are sexually mature, they continue to undergo selection, generally by different criteria than during childhood, so selection will tend to favor different characteristics depending on when the animals reproduce. But the sticking point is what is "quick" evolution? It supposes some end-point you can measure, but in a laboratory test the speed of selection will depend on the characteristic. For example, a condition causing stillbirth will be selected out of the population most quickly if animals breed when young, since more of the non-stillbirth alleles are passed through to the next generation by the larger number of young survivors. And of course breeding while young reduces the generation time for an overall increase in speed of evolution. But a condition causing heart attacks in older giraffes will not be selected against at all if only the young breed, so there older breeding does indeed 'speed up' evolution. Where this probably comes in to ongoing research topics of interest is with invasive species, since it is well established that special conditions occur at the advancing front of an insect pest as it spreads across a continent (for example, bigger wing muscles so they fly faster). Presumably invasive species at the front also tend to focus their selection more on traits that encourage survival to the first breeding rather than to later breedings, since those later individuals are left somewhere behind in the infected area. Wnt (talk) 14:26, 28 December 2014 (UTC)[reply]

I agree with that, although I think the OP is indeed quite confused, as the question pretty clearly indicates a Lamarckian understanding, which is definitely wrong. But let me mention another factor. Recent studies have shown that males steadily accumulate mutations as they age, which show up in their sperm. (This doesn't happen so much to female egg cells, which are all present at birth.) So, older fathers tend to produce offspring with higher levels of variation. One result is a higher incidence of genetically-related problems such as autism. Another result may be a higher incidence of beneficial mutations, but the data so far don't favor that as far as I know. Looie496 (talk) 14:47, 28 December 2014 (UTC)[reply]

it is only after reading the discussion that i know i'm inclined to lamarckism. Provided i follow that, the above question has some sense. I wanted to know how cockroaches adapt generations after generations to the toxins that we spray (not just through genes because adaptations may be somatic). There should be something else.. a musician's son plays music well or easier. Also i doubt if a guy with low iq has an earlier child with low iq and after he becomes brilliant, his later child would have increased iq (let's no consider the influencing factors like mother's iq)??? — Preceding unsigned comment added by 122.164.133.100 (talk) 15:34, 28 December 2014 (UTC)[reply]

Lamarckism has long been widely denounced; it is also worth noting that Lamarck had some pretty vague philosophical notions. Darwin himself proposed a theory of inheritance of acquired characteristics which was founded on the notion of "gemmules", which in his usage referred to the transmission of genetic information from cell to cell. After decades of denunciation, it turns out that there is limited support for some ideas of acquired inheritance via epigenetics, such as in the variable yellow mouse, and in fact some people have gone back and shown that Lysenko's original ideas (taken from conversations with Russian peasant farmers) of conditioning plant seeds to a new environment have some truth to them. There is no known route to go from epigenetic conditioning over a few generations to permanent inheritance. However, that said, it is known that small RNAs like miRNA can influence chromatin configuration, which can influence DNA methylation, and that DNA methylation can cause transition mutations, C to T, G to A; and the GC content of DNA is in fact far from random, e.g. at CpG islands. And either small RNAs or hormones that influence their levels, or influence chromatin directly, may be distributed throughout the body (with small RNAs it varies a lot by organism though). So I should encourage you, but at the same time, exercise caution, as this is neither proven nor is it all that likely to have a major overall effect in long-term evolution. Wnt (talk) 16:38, 28 December 2014 (UTC)[reply]

You seem to be labouring under some misconceptions. First of all, there is some dispute as to whether giraffes evolved with longer necks so they could reach higher leaves or whether the long neck evolved as a secondary sexual characteristic see:Girrafe#Neck. Secondly, cockroaches and other animals adapt to the toxins used to control them by Survival of the fittest. Most of them die from the toxins but the few that have a natural immunity to them - because of genetic mutations - live and go on to breed and produce resistant offspring. Also, someone with a low IQ doesn't later become brilliant - the IQ changes little throughout life. And lastly, some musicians' sons play well, either through nature or nurture, and some don't play at all. Richerman (talk) 17:08, 28 December 2014 (UTC)[reply]

thanks.. misconceptions might have arose because of disputes in theories. Giraffes' reason for evolution is not the debate but process of passing the better qualities in them is. Secondly, camouflaged butterflies duck their predators upon seeing the others' misfortune, they are not survivors that are selected because they are the fittest but they are the existing ones that fit themselves to survive, via generations. Genetic mutation might have a cause or a reason. Many times it is a Cause that goes futile or is helpful in getting good qualities. Other times it (mutation) is formed because of previous similar exposures to threats. Nothing happens without a reason. IQ point is just an example, i wanted to know if someone refines himself of certain qualities in his later half of life, the baby that is born then be affected with those or not. Your answer is no. Fine. Lastly, there is an old proverb that says family work-expertise runs through generations. The gene that carries the music-expertise information is passed on to his son and it is the son's wish or interest to pursue further (apart from environmental influence). People only wonder if a musician's son doesn't play music well (even if his father is not nearby to nurture). — Preceding unsigned comment added by 122.164.133.100 (talk) 18:55, 28 December 2014 (UTC)[reply]

Expanding Earth vs. plate tectonics

Where is the coup de grace from satellite measurements that shows that the "expanding Earth" theory can't be right? I have looked for it for hours and all I find is waffle or deleted pages. Surely satellites such as LAGEOS II have settled this issue by now? Why the fog? Captainbeefart (talk) 13:38, 28 December 2014 (UTC)[reply]

According to references in the article on Expanding Earth, this has been proven without using satelites - so why waste satellite time (which is not cheap) on it? WegianWarrior (talk) 14:33, 28 December 2014 (UTC)[reply]

It is not a theory but a hypothesis. So one runs with those hypothesis that gains ground on any evidence as it accumulates which can be independently cross-matched, to upgrade that original hypothesis into a theory. Whilst any hypothesis that can't attract such evidence, fades into obscurity. There are only 24 hours in the day and scientists have better things to do, than waist time in debunking each and every hypothesis that was ever imagined.--Aspro (talk) 15:07, 28 December 2014 (UTC)[reply]

"waist time" = time to eat leftovers, so they go to your waist instead of going to waste. StuRat (talk) 16:04, 28 December 2014 (UTC) [reply]

If the Earth was expanding, why would we have subduction zones, caused by plates running into each other ? StuRat (talk) 16:10, 28 December 2014 (UTC)[reply]

Indeed, there are many ways to easily show that the expanding Earth hypothesis is wrong - Expanding_Earth#Scientific_consensus lists eight different ways that this has been done without the need for satellite data. So there is clearly no need to use satellites to debunk an already completely and utterly debunked idea.

If you look at Expanding_Earth#Present_day_advocates, you'll see that the main advocates of this unlikely idea are:

J. Marvin Herndon - a scientist with no really specific credentials in this area who is widely known for producing reams of ideas that are contrary to what is already known and well-proven.
Neal Adams who has no scientific qualifications whatever and who works as a comic-book artist.

I'm also not clear what you imagine the satellite might measure that would be better than measurements we do here on earth. The hypothesized expansion rate would be of the order of millimeters per year - and there is no way for a satellite camera to image the entire earth to sufficient precision to do that - nor to observe for long enough to measure a more substantial change over decades. Measurements of the distance between two fixed points on earth might produce some results - but we already do that using the reverse approach of using GPS satellites to tell us where we are on the ground and thereby measure how the ground is moving - and those results merely confirm that there is no uniform expansion.

If you have an idle moment: http://what-if.xkcd.com/67/

SteveBaker (talk) 17:14, 28 December 2014 (UTC)[reply]

This xkcd is generally good but it has one fairly clear error: it suggests the density of an expanding Earth would have to increase in order for it to collapse into a black hole. But as explained at that article, a 10⁸ solar mass black hole has the density of water. The density of Earth's inner+outer core is at least 10 times that, and according to the article the density needed to make a black hole is inversely proportional to the square of the mass, so a 10^7.5 solar mass Earth would contain a black hole even if by plot device we suppose it defied the Chandrasekar limit and Tolman–Oppenheimer–Volkoff limits. It would become one soon after; the zonation of this seems determined by File:EarthGravityPREM.svg, assuming proportional increase in all accelerations. Wnt (talk) 21:14, 28 December 2014 (UTC)[reply]

I suggest that you guys have missed my point. I apologize for not having explained it well enough. Opinions and received wisdom are death to science. Read about Chladmi and weep. Never mind the secondary evidence. There must by now be primary evidence. I know that radio telescopes all around the globe stop at a particular point in the day and then all focus on a source in Orion and then talk to one another for ten minutes. They establish exactly where they are on the geode relative to one other. They corrected for the jump in the crust of the Earth when the great earthquake occurred off Indonesia with such horrible consequences not all that long ago. The telescopes provide primary evidence of drift. Satellites such as LAEOGIS II were designed to do the same thing. Ray Charles could have seen that the OBSERVED pattern of drift of points on the surface of the planet would have to have been different if (1) Carey was right or (2) Wegener was right. There ought by now to be a PRIMARY stake though the heart of Carey's delusions but I can't find it. I meet with blank pages at NASA and Ah-Ya elsewhere. In reply please spare me your shallow opinions about what you think you believe. Point me at THE EVIDENCE and I shall forever be in your debt.... Captainbeefart (talk) 13:15, 29 December 2014 (UTC)[reply]

Expanding_Earth#Scientific_consensus (and the references it links to) are it. That's the evidence - it's compelling and completely debunks the expanding earth concept. There is simply no need to go to all the trouble you describe. We don't go to a lot of trouble to dispel the flat-earth myth either. SteveBaker (talk) 17:13, 29 December 2014 (UTC)[reply]

Blood-alcohol level

Quoting Drunk driving in the United States:

Federal Aviation Regulation 91.17 (14 CFR 91.17) prohibits pilots from flying aircraft with an alcohol level of 0.04% or more, or within eight hours of consuming alcohol, or while under the impairing influence of any drug.

Maybe it's because I've never consumed much alcohol, but I don't understand how you could have any alcohol in your system 8+ hours after drinking any, unless you were so badly drunk as to be in a medical emergency when alcohol levels were at your peak. What am I missing? Nyttend (talk) 15:27, 28 December 2014 (UTC)[reply]

When you get down to that level you might get there without drinking booze. Rum cake, medications, etc., might be enough. StuRat (talk) 16:07, 28 December 2014 (UTC)[reply]

It is quite possible, and not abnormal, for such levels to remain in the system for more than 8 hours after only a "normal" session of drinking. Here in the UK, one general rule-of-thumb says you lose about 1 unit per hour, and a unit is around 1/3 of a pint of beer or half a glass of wine. So just 4 glasses of wine could keep you over the limit 8 hours later. The specific rate varies greatly depending on ones metabolism.[11] Over the festive season, a great many drivers are breathalysed 'over the limit' the morning after Xmas parties. Hopefully not too many pilots though. Igor the facetious xmas bunny (talk) 16:22, 28 December 2014 (UTC)[reply]

This is a very complicated matter...and the difficulty is how to encapsulate that into a rule that is both easy for a pilot to understand - and legally enforceable, should the need arise.

An excellent reference as to how alcohol is removed from the body is here [12] - it points out dramatic differences in the rates that alchol is removed - women have different removal rates than men, East Asians and Native Americans have very slow removal rates, older men and menopausal women get intoxicated on less alcohol, frequent heavy drinkers can also metabolize the stuff more quickly, and people with liver damage, more slowly.

Even more complicated is the way that alcohol enters the blood stream through the digestive tract. If you eat a good sized meal before drinking, the alcohol remains in the stomach (where it is absorbed into the blood fairly slowly) - but if you don't, the alcohol quickly runs into the small intestine where it's absorbed almost immediately. So if someone eats a lot, then drinks a lot, the blood alcohol levels would continue to climb long after they stop drinking. Carbonated drinks are absorbed more rapidly than non-carbonated. Diet sodas increase the rate of absorption compared to sugary soda.

So neither the blood-alcohol level or the time-since-last-drink measurements are perfect predictors of one's ability to fly a plane. Relying on just the blood-alcohol levels would not fairly account for the problem of older men/menopausal women being more intoxicated with less alcohol - and time-since-last-drink doesn't account properly for differing rates of metabolism between different people. Adding both requirements is at least some kind of a band-aid to better ensure that the pilot is unlikely to be intoxicated while flying.

However, I suspect that the hours-since-last-drink rule is there for legal reasons. You can't always pull a pilot out of the plane before take-off to administer a blood-alcohol test right there and then...but hours, days or weeks after a pilot is suspected of having committed some horrible error due to being intoxicated, you can find eye-witnesses to him having been drinking at a party late the previous night - and you can prosecute on the hours-since-last-drink rule.

Hours-since-last-drink is also a good rule for the pilot himself. If he has a few drinks and wonders if he's OK to fly - he can't very well predict what his blood alcohol levels will be by the time he's on board the airplane ready to go (because he's a moderate drinker with a small amount of liver damage, ate a moderate - but not huge - amount of food while drinking, mixed diet coke with his rum, and has a Native American father). But if the rule is really simple...he can think: "I'd better leave the party before midnight because I'm flying to L.A at 9 o-clock tomorrow."

SteveBaker (talk) 16:37, 28 December 2014 (UTC)[reply]

As SteveBaker says, the rule is there partly for convenience of the pilot, as well as the convenience of enforcement. There have been cases of pilots being arrested on entering the cockpit, after stopping at an airport bar during a layover, and it isn't necessary to breathanalyze, as long as it is known that what the pilot consumed at the bar contained alcohol. For convenience of the pilot, if he leaves the party before midnight and enters the cockpit at 9 am, he is clear on the clock rule. Robert McClenon (talk) 18:08, 28 December 2014 (UTC)[reply]

Also, it is my recollection that a decrease in air pressure affects the effect of blood alcohol (even if the blood alcohol is itself what would normally considered a trace quantity). Even if the pilot was qualified to drive to the airport, and to take the plane off, he may not be qualified to continue the climbout when the plane is pressurized to effective 4000 feet or effective 8000 feet. There is also a caveat that I don't entirely recall having to do with increases in pressure, but the basic idea is that one should not go scuba diving one afternoon and then fly the next morning. At least that is what I recall from private pilot training 35 years ago. If you fly a light plane to an island, don't go scuba diving on your last day, if you plan to fly the light plane home. Robert McClenon (talk) 18:08, 28 December 2014 (UTC)[reply]

8 hours "bottle to throttle" is simply to make sure all alcohol is metabolized. It's secondary to the 0.04 limit meaning if you are 0.04 after 8 hours, you are considered impaired. A heavy drinker may still be above 0.04 after 8 hours. The scuba rule has to do with the bends as all flight has a pressure altitude above sea level. Blood will start outgassing dissolved nitrogen at altitude (or cabin pressure). --DHeyward (talk) 19:48, 28 December 2014 (UTC)[reply]

Hmmm...the scuba rule makes perfect sense - but shouldn't it also be applied to passengers? At least it should be really well publicised. SteveBaker (talk) 19:59, 28 December 2014 (UTC)[reply]

That is likely true, but it may be that the risk of "bends" 24 hours is small but not zero, and that the amount of discomfort to be expected may not be a health risk to a passenger, but is a safety risk to the aircraft and its passengers. Robert McClenon (talk) 21:20, 28 December 2014 (UTC)[reply]

It needn't be publicized by the airlines as it is stressed during recreational diver training as an important rule to follow to avoid DCS. Many dive resort arrange land-based activities and tours for the last day of a dive vacation. A "Time to Fly" countdown is indicated on most dive computers, with some simply using a 24 hour countdown, while others calculate a safe time to fly based on actual nitrogen absorption and off-gassing calculations . -- ToE 14:43, 29 December 2014 (UTC)[reply]

"I don't understand how you could have any alcohol in your system 8+ hours after drinking any, unless you were so badly drunk as to be in a medical emergency" is completely silly, for any definition of medical emergency that makes sense. Greglocock (talk) 23:39, 28 December 2014 (UTC)[reply]

I completely agree. It's quite common for people to assume that after a night of partying, they can sleep for 8 hours and then safely drive home...for sure, that's not guaranteed to be the case. It's easily possible for there to be a legally unacceptable blood-alcohol level present, even 8 hours later. The (very approximate) rule of 1 unit of alcohol being removed from your bloodstream per hour and 2 units being an unsafe level to drive with tells you that after 10 drinks, 8 hours ain't enough to get you sufficiently sober to drive a car. But that number is an exceedingly approximate rule of thumb...and plenty of individuals will metabolize the alcohol more slowly than that. Also, the presence of food in the stomach while drinking, avoiding fizzy drinks and staying clear of artificial sweeteners are all well known tricks to avoid getting drunk too quickly - but all they are really doing is slowing down the absorption rate - which makes the likelyhood that you're still over the limit the next morning much higher. This is a complex biological system - and these simple rules are really seriously wrong for some kinds of people in some kinds of situation.

I also believe that even if the alcohol has indeed been metabolized away after 8 hours, a severe hangover is every bit as big an impairment to good driving/flying as being mildly intoxicated...so the hours-since-last-drink rule is good for that reason also. SteveBaker (talk) 17:10, 29 December 2014 (UTC)[reply]

Heavy water

In the so called heavy water plants around the world, is heavy water manufactured or just separated from a lot of ordinary water. The article is not clear about this.--86.176.8.21 (talk) 16:15, 28 December 2014 (UTC)[reply]

I am not entirely sure what you mean. It is made from various treatments of "normal" water (and various other chemicals may be involved); it is not made of thin air! Is that 'manufacturing'? I do not know. Everything comes from some form of raw materials; in this case, the raw material is indeed mostly water. So yes... heavy water is mostly made from water. Whether you consider it 'extracted' or not is moot. Igor the facetious xmas bunny (talk) 16:28, 28 December 2014 (UTC)[reply]

It could indeed be made from air, by combining oxygen from the air with heavy hydrogen, which while rare in the air, is present at some level. However, I think it is extracted from water, by just separating it, using a series of centrifuges, since heavy water is a bit heavier, as the name implies. StuRat (talk) 16:37, 28 December 2014 (UTC)[reply]

[edit conflict] There's a small amount of heavy water in ordinary water, so maybe it's extractable, but it may also be possible to force some weird chemical reaction to convert ordinary water into heavy water. This is the distinction between "manufactured or just separated". Conversely, you could perhaps synthesise it from thin air; water vapour is in the atmosphere, so you'd just need to run a dehydrator machine and use its water for the weird chemical reaction. Nyttend (talk) 16:41, 28 December 2014 (UTC)[reply]

Well separation by the kinetic isotope effect usually using the Girdler sulfide process is a chemical way to obtain heavy water, but ordinary water cannot be converted to heavy water by any chemical reaction any more than lead can be converted to gold by chemistry. Creation of heavy water from normal water (or normal oxygen and hydrogen) would require a physical process but is not practicable in significant quantities, just as creating gold is not practicable. Nearly all deuterium that exists was created in Big Bang nucleosynthesis. Dbfirs 17:18, 28 December 2014 (UTC)[reply]

It's produced by distillation, typically with the assistance of chemical processes. Details here and here. Short Brigade Harvester Boris (talk) 17:27, 28 December 2014 (UTC)[reply]

Initially, (late 1930's) the only source of heavy-water was by separating naturally occurring DiDeuterium monoxide (heavy-water) from ordinary water. As there is little in ordinary water, this extraction process was very expensive. With the development of nuclear reactors, ordinary water could be subjected to a high neutron flux in the reactor so that the hydrogen nucleus had a chance of capturing a neutron. They do this all too readily, which is why ordinary water is not much good as a moderator, since the water soaks up the free neutrons, leaving few for the continuation of a chain reaction (OK, this is a bit more involved than that but that is a subject for a separate question). If the resulting heavy-water so produced, is then concentrated to make it suitable as a moderator in a heavy-water reactor, some of those heavy deuterium atoms may then absorb another neutron and they becomes tritium atoms. Those tritium atoms can then can be separated off and used for such applications as beta lights and boosters for thermonuclear devices. --Aspro (talk) 17:51, 28 December 2014 (UTC)[reply]

Yes, I thought that bombardment with neutrons would work, but I couldn't find evidence of it actually being used to produce heavy water. I guess that it's just an expensive way to do it compared with the chemical separation process that I mentioned above, since normal water is less common in reactors these days. Dbfirs 18:09, 28 December 2014 (UTC)[reply]

Yes, to produce heavy water in quantity, then the processes you link to is the only economic way to do so. The Germans in the late 1930's used electrolysis with potassium hydroxide as the electrolyte. By all accounts it was not very productive compared with more modern methods.--Aspro (talk) 20:28, 28 December 2014 (UTC)[reply]

As the previous posters have said, "manufacturing" of heavy water in the sense of the production of deuterium would require a nuclear reaction, not a chemical reaction. Deuterium can be isotopically extracted from protium either in the form of water or in the form of the gas. I am not aware of any practical efforts to create deuterium. It is extracted, either as the gas or as water. Given that water is abundant and the gas is flammable and has to be obtained itself from water, I think that water is the better starting point. Robert McClenon (talk) 18:13, 28 December 2014 (UTC)[reply]

Isotopic Separation and Enrichment goes into deuterium and other other isotopes separation methods used in industry and adds some interesting background.--Aspro (talk) 20:38, 28 December 2014 (UTC)[reply]

Thanks for the interesting link. Would you like to use that document to expand our article on the Girdler sulfide process? Dbfirs 20:53, 28 December 2014 (UTC)[reply]

Someone else may. I fear I am spreading my free-time over too many areas already and I have a growing list of WP articles that need complete re-writes. Just can't find enough quality time to tackle them properly. There may be better sources too (I just Googled: potassium, Germans, Telemark, electrolysis and that pop out. The inclusion there of the Girdler sulfide process was just a serendipitous coincidence. ). A Boolean search may be more productive.--Aspro (talk) 22:19, 28 December 2014 (UTC)[reply]

Does lemon juice dissolve polystyrene foam ?

I filled a polystyrene foam (commonly called Styrofoam) cup with lemons and water (no sugar), left it in the fridge for a couple days, and found the polystyrene foam on the inside, below the water line, was heavily eaten away. Was this a defective cup, or would they all do this ? StuRat (talk) 20:08, 28 December 2014 (UTC)[reply]

Yes, in the UK, these cups are not supposed to be used with any ~~acidic~~ lemon drink because of this problem. Dbfirs 20:35, 28 December 2014 (UTC)[reply]

I don't think the hydrocarbon chains in polystyrene should be broken by acid. Far more likely is that some oil in the lemon peel ended up in the lemonade, and dissolved the polystyrene wherever it touched the cup. This is the reason why only the region just under the water line was affected - because the lemon oil is lighter than the lemonade, so it floats on top. Wnt (talk) 20:53, 28 December 2014 (UTC)[reply]

Yes, thanks for the correction, it's not the acid but the lemon oil that's the problem. Dbfirs 21:00, 28 December 2014 (UTC)[reply]

How sure are you that the cup was polystyrene and not some other more environmentally friendly biodegradable alternative? SteveBaker (talk) 23:09, 28 December 2014 (UTC)[reply]

It was white, if that helps. In any case, the lemon oil/polystyrene interaction seems likely to be the explanation. Thanks, all. StuRat (talk) 17:23, 29 December 2014 (UTC)[reply]

Humans are more closely related to cows/pigs/sheep than parrots are to chickens?

Is this true or false? It's a factoid I've seen quoted a few times in relation to discussions of whether a parrot eating some chicken is an example of cannibalism (which it obviously isn't, yet a lot of people seem to disagree) and therefore morally wrong. --Kurt Shaped Box (talk) 21:46, 28 December 2014 (UTC)[reply]

You'd have to decide on a way to measure the differences. Percent DNA in common ? Time since the last common ancestor ? It seems quite possibly true to me, either way. StuRat (talk) 21:52, 28 December 2014 (UTC)[reply]

Either way will be fine - whichever one is possible to answer... --Kurt Shaped Box (talk) 22:03, 28 December 2014 (UTC)[reply]

Morality is a human invention. It applies only to human behavior, not to animal behavior. ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:57, 28 December 2014 (UTC)[reply]

Haha. Try telling that to some parrot owners! :) --Kurt Shaped Box (talk) 22:03, 28 December 2014 (UTC)[reply]

In the case of a parrot eating a chicken, I would think it would be the chicken's owner complaining about cannibalism. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:07, 28 December 2014 (UTC)[reply]

By any measure, humans are much more closely related to their fellow mammals cows, pigs and sheep than any of those are to birds. Humans are in the same phylogenetic magnorder as the other placential mammals mentioned, whereas they are in the same phylogenetic superclass as birds. The Synapsids (the reptilian ancestors of mammals) diverged from the sauropsids (the reptilian ancestors of modern reptiles and birds) some 325 million years ago, about 90 million years before dinosaurs appreared. The line leading to humans diverged from the line leading to cows, pigs and sheep a lot more recently, within the last 65 million years, after the dinosaurs (except for the birds) had gone extinct. Dominus Vobisdu (talk) 22:27, 28 December 2014 (UTC)[reply]

I think you misread the Q, which asked about how closely parrots and chickens are related to each other. StuRat (talk) 22:32, 28 December 2014 (UTC)[reply]

I see. Then the answer is that the ancestors of humans diverged from those of cows, pigs and sheep at about the same time as the ancestors of parrots diverged from those of chickens, that is, about 65 million years ago, give or take a million years or two. Parrots and chickens are not particularly closely related members of the bird order. Dominus Vobisdu (talk) 22:47, 28 December 2014 (UTC)[reply]

Nope - good try. Like mammals, birds diversified tremendously after the asteroid hit the Yucatan... but Galloanseres diverged from Neoaves much earlier, 90 million years ago. There has just been some spectacular action on this front - see [13]. Wnt (talk) 23:04, 28 December 2014 (UTC)[reply]

The most recent ancestor of parrots and chickens is the common ancestor of Neognathae. The most common ancestor of primates and pigs is the Boreotheria, which links the Euarchonta to the Cetartiodactyla. Both deeper groups predate the KT boundary. Let us know if reading these articles is not helpful. μηδείς (talk) 04:25, 29 December 2014 (UTC)[reply]

From the figure published for the bird genome poject, the most recent common ancestor of parrots and galliformes (chickens etc.) is put around 90 million years ago, our Euarchontoglires article says they probably split from the Laurasiatheria sister group about 85 to 95 million years ago, so the same ballpark. However, falcons and parrots have a more recent common ancestor, so by this rather peculiar moral measure, a falcon eating a parrot is almost as much cannibalism as, say, a human eating a rabbit. [confirmation of dates needed]. . . dave souza, talk 10:58, 29 December 2014 (UTC)[reply]

Falcons and (parrots and songbirds) split shortly after the KT event (see Nat Geo summary of recent article), While primates and glires (rabbits and rodents) split well before. μηδείς (talk) 17:29, 30 December 2014 (UTC)[reply]

I'm not sure why, but there really does seem to be a belief that a bird eating another bird or a bird eating the eggs of another species is an act of cannibalism. I've seen it cause arguments in the comments of YouTube videos. --Kurt Shaped Box (talk) 16:01, 29 December 2014 (UTC)[reply]

The reason is that we can distinguish features better on things more similar to us. This is the same reason why a starfish is called that, despite it being about as far from a fish as is possible for any animal. Nobody would ever mistake a human for a chimp, yet a dolphin or porpoise could easily be confused, as could an alligator or crocodile. Even people of different races are sometimes hard for us to distinguish. StuRat (talk) 17:17, 29 December 2014 (UTC)[reply]

December 29

Is there a correlation between G6PD deficiency to allergy to penicillin?

I mean to ask if people who have G6PD have allergy to penicillin 149.78.225.73 (talk) 05:14, 29 December 2014 (UTC)[reply]

A pubmed search: [14] gives only 10 hits, and none that deal with type I, IgE mediated penicillin allergy. Judging by the titles and abstracts, the most relevant papers are about hemolytic adverse drug reactions. If a patient with G6PD deficiency were to have a penicillin-induced hemolytic drug reaction, it is possible that the reaction would be more severe than in a patient without the deficiency. Penicillin-induced hemolytic drug reactions are very rare (less than 1/10 000 Source in Norwegian, sorry). This information is not intended as medical advice. If you are a G6PD deficiency patient, and worried about taking penicillin, consult a doctor. --NorwegianBlue^talk 14:48, 29 December 2014 (UTC)[reply]

Why is jet fuel measured in pounds and not in gallons?

I wasn't sure which Reference Desk to use, so I settled on this Science Desk. I was reading about that Indonesian plane that went missing a day or two ago. I read, in the news, the following statement: "Looking at the flight's paperwork, the plane had more than 18,000 pounds of jet fuel at takeoff, enough to fly about 3 1/2 hours ...". It struck me as quite odd that jet fuel (a liquid) would be measured in "pounds". Is this an error in the news report or is "pounds" the correct measurement for jet fuel? If the latter, why would that be the case? Thanks. Joseph A. Spadaro (talk) 05:29, 29 December 2014 (UTC)[reply]

It's usually in pounds or other units of weight, just as fuel for ships is measured in tons. I've always assumed that in both cases it is because weight is a critical factor in performance (e.g., keeping an airplane aloft or a ship afloat) though I don't really know. Short Brigade Harvester Boris (talk) 05:40, 29 December 2014 (UTC)[reply]

Yes, I imagine that weight is a critical factor for planes and boats. But, wouldn't the same concerns be addressed by measures of liquid volume, just as easily as by pounds and tons? I assume it's a simple conversion. So, let's say that we have this hypothetical situation: this airplane can only be flown with a maximum of XXX pounds of fuel. Can't they just convert pounds to a typical liquid measure and say the same thing, with the same result? Namely: this airplane can only be flown with a maximum of YYY gallons of fuel. Am I missing something? Also, if it's so "easy" and "convenient" and "practical" to simply use pounds, why do we bother with other units of liquid measure, as a general rule, anyway? Thanks. Joseph A. Spadaro (talk) 05:53, 29 December 2014 (UTC)[reply]

Could it be because the volume of fuel changes with altitude? -- Calidum 06:00, 29 December 2014 (UTC)[reply]

Hmmm. I have no idea. But, if the volume changes, wouldn't the weight also proportionally change? Or no? Joseph A. Spadaro (talk) 06:06, 29 December 2014 (UTC)[reply]

I suspect that the preference for weight measurement rather than volume is that the volume of a given mass of fuel varies with temperature - and aircraft may be refuelling at locations with large variations in temperature. AndyTheGrump (talk) 06:04, 29 December 2014 (UTC)[reply]

Yes, volume will vary by pressure and temperature. Weight should only vary by gravitational field changes, although acceleration of the plane may appear to make it vary. Mass should never vary at all. StuRat (talk) 06:10, 29 December 2014 (UTC)[reply]

Well, the total weight of the plane matters, not just to determine if the plane can take off, but in determining how much fuel it takes per minute to keep the plane aloft. So, you'd need to constantly convert fuel to pounds and then add it to the weight of the planes, passengers, crew, luggage, and cargo. It's a lot easier just to start with pounds.

As to why not always use pounds, I suppose you could, but it's generally easier to measure liquid by volume, as all you need is a graduated cylinder, not a precise balance scale. StuRat (talk) 06:05, 29 December 2014 (UTC)[reply]

OK, thanks. So ... the volume and the weight do not vary proportionally? They vary at different rates, according to the temperature (and other factors)? Joseph A. Spadaro (talk)

That suggests an interesting question. As the plane increases altitude, everything on board the plane, as well as the plane itself, loses weight. So, since I can't recall from 9th grade science class, does the weight vary proportionally for everything? I would think it would, but maybe someone can confirm that. As a simple example, a 10 pound little plane or drone is carrying a 1 pound payload. Let's also assume it can go ridiculously high. By some altitude or another, the plane's weight should have dropped to 9 pounds, for example, but its payload should also have dropped, to .9 pounds - so the plane is lighter, but is also carrying proportionally less weight. Right? ←Baseball Bugs ^{What's up, Doc?} carrots→ 06:29, 29 December 2014 (UTC)[reply]

Hmmm. That is interesting. But, I was actually suggesting something altogether different. I assume that there is some "conversion factor" (i.e., a formula) that translates pounds into gallons and vice versa. So, according to this (How Do I Convert Pounds To Gallons?) ... Pounds = (Gallons * 8.345). But, wouldn't that conversion formula only work in a certain temperature? And then, if we move to a different temperature, we have to use a completely different conversion formula? Joseph A. Spadaro (talk) 06:40, 29 December 2014 (UTC)[reply]

Pounds at a particular altitude, such as see level. A quick rule of thumb is, "a pint's a pound the world around". That works in the kitchen, anyway. ←Baseball Bugs ^{What's up, Doc?} carrots→ 06:52, 29 December 2014 (UTC)[reply]

Um, nope. The U.S. pint is approximately 473 mL, while the Imperial pint is approximately 568 mL - a difference of 20%. Even in the kitchen, that is rather a large error. And come to think of it, the fact that there are two different non-metric measures of volume may be another reason to prefer weight for jet fuel. A 20% error there could be rather embarrassing. AndyTheGrump (talk) 06:57, 29 December 2014 (UTC)[reply]

Well, we have the metric system to thank for this incident. -- Calidum 07:01, 29 December 2014 (UTC)[reply]

Not really - we have a chain of events starting with malfunctioning equipment, and ending with the incorrect use of a figure for pounds per litre instead of kilogrammes per litre to thank for it. If the metric system had been used consistently from the start, and the aircraft hadn't been flown in a state where fuel usage couldn't be properly monitored, the accident wouldn't have happened. AndyTheGrump (talk) 07:11, 29 December 2014 (UTC)[reply]

In principle the weight of things decreases with increasing altitude; gravitational attraction varies inversely with (the square of) one's distance from the center of the Earth. However, the radius of the Earth is about 4000 miles, and most air traffic tops out at less than 10 miles: a trifling 0.25% further out, reducing weights by about 0.5%. (Even the "edge of space" – the Kármán line – is drawn at 62 miles (100 km), so the distance from the center of the Earth is only increased by about 1.5% even at that boundary.) TenOfAllTrades(talk) 07:54, 29 December 2014 (UTC)[reply]

Yes, density changes with temperature. Like most substances, jet fuels (and avgas) are denser at lower temperatures. The volume of a pound of fuel changes by more than 5% when going from -40°C to +20°C: page 22. (That's the difference on the ground between Alaska and the California coast in the winter, say, or the difference between San Francisco on the ground and San Francisco at about 40,000 feet: cruising altitude.) As with most liquids, the effect of pressure – from 1 atmosphere at sea level to about 0.2 atmospheres at cruising altitude – on density technically exists and is measurable with suitable tools, but is practically negligible for this purpose. TenOfAllTrades(talk) 07:54, 29 December 2014 (UTC)[reply]

Thanks. But, I'm still confused on this point. There is some "conversion factor" (i.e., a formula) that translates pounds into gallons and vice versa. So, according to this (How Do I Convert Pounds To Gallons?) ... Pounds = (Gallons * 8.345). But, wouldn't that conversion formula only work in a certain temperature? And then, if we move to a different temperature, we have to use a completely different conversion formula? I thought (per above discussion) that changes in weight and volume are not proportional and are dependent upon the temperature? So, if that's the case, wouldn't we need (and use) different conversion formulas for different temperatures? Joseph A. Spadaro (talk) 07:27, 29 December 2014 (UTC)[reply]

To more clearly and directly answer that question: The formula is approximately correct for determining the mass in Avoirdupois pounds (of about 453.5g) of one US liquid gallon (of approximately 3.785 litres) of water at 4 °C (and normalish pressures). It's not suitable for most jet fuels (probably not for any), and its accuracy for water goes down as temperature goes up, although it remains good enough for most household purposes at naturally occurring temperatures. --Stephan Schulz (talk) 15:01, 29 December 2014 (UTC)[reply]

OK, thanks. So, let's ignore the formula for water and discuss the formula for another liquid (namely, jet fuel). I assume there is such a formula, and that it happens to be somewhat different than the "water formula" I cited above. Nonetheless, would not the formula always change, dependent upon what the temperature is in a given spot? Joseph A. Spadaro (talk) 15:54, 29 December 2014 (UTC)[reply]

Yes, there is such a formula - in fact, it's essentially the same formula with a different constant. If you check jet fuel, you will find that there are different kinds with different physical properties, but standard jet fuel has a density of about 0.81kg/l or 1.79lb/l or 6.76lb/US gallon. That formula strictly only applies at 25 °C. If the fuel is significantly warmer or colder, it needs to be adjusted. Since jet fuel is a mixture of different carbohydrates, I suspect the pragmatic solution is to just have a sufficiently narrowly specified table, or an empirical formula. The effect is not huge for realistic temperature ranges, but easily measurable - I guess on the order of a few percent, if you go from -30 °C to 20 °C. --Stephan Schulz (talk) 17:13, 29 December 2014 (UTC)[reply]

Thanks. Got it. Joseph A. Spadaro (talk) 16:59, 31 December 2014 (UTC)[reply]

Going back to the original question, jetfuel is commonly measured by mass (pounds or kilograms) since it lets you a) know how heavy your aircraft is and where the CG is (weight and balance is rather critical to know for obvious reasons), and b) how much energy you have available. Volume - and therefore energy density - can change rather dramatic between a hot tarmac and 50.000' in the air, but the total mass do not. Luckily the dielectric permittivity of jet fuel changes more or less proportionally with the temperature (jet aircraft commonly uses capacitive probes as fuel gauges). WegianWarrior (talk) 07:43, 29 December 2014 (UTC)[reply]

The pilots of most aircraft work in litres or gallons. The capacity of the tanks in their aircraft is specified in litres or gallons; they purchase their fuel from the fuel supplier by specifying the required number of litres or gallons; they memorise their specific fuel consumption in litres per hour or gallons per hour. However, to calculate the total weight of their aircraft at take-off, and at landing, they must multiply the fuel volume by the density of the fuel. Pilots memorise fuel densities such as 0.75 kg/L or 6 lb/US gall or 7.3 lb/Imp gall.

For very large aircraft that fly very long distances and carry very large amounts of fuel, the aircraft manufacturer specifies fuel capacities as a mass (or weight). They specify specific fuel consumptions and specific air ranges as kg/hour or kg/km or pounds/nautical mile etc. Also, operators purchase their fuel by specifying the required mass (or weight), and they do their flight planning using mass (or weight). There are several advantages in this approach. Firstly, when the pilot calculates the total weight of the aircraft there is no need to multiply by the fuel density. Secondly, to reach its destination safely the aircraft requires a certain amount of energy - this is closely related to the mass (or weight) of the fuel and less so to the volume of the fuel because the density of fuel varies with temperature. It is the responsibility of the fuel supplier to know the prevailing density of his fuel and to work out how many litres or gallons will be required to supply the number of kilograms or pounds specified by the pilot. For a small aircraft, the variation in density of the fuel with temperature has an insignificant effect on the amount of fuel required to reach the destination. But for a very large aircraft, especially one travelling large distances between usable airports, the variation in density of the fuel with temperature is not insignificant. Dolphin (t) 08:00, 29 December 2014 (UTC)[reply]

The "conversion factor (i.e. a formula)" is just the density of the fuel. To convert pounds to gallons, multiply by the density in pounds per gallon. To convert gallons to pounds, divide by it. But, as stated, the density is not a constant but depends on temperature. The mass is more important than the volume for the reasons Dolphin states.

There was an incident in 1983 that is relevant to this. The electronic fuel gauges on a Boeing 767 had failed, and due to some miscommunications, the pilots thought it was acceptable to fly in that situation as long as the fuel quantity was checked by a "drip test" and entered into the flight computer. The drip test was done after fueling and provided the volume in the tanks, in liters, this being Canada. The fuel supplier was responsible for telling the pilots the density of the fuel and provided the number 1.77, meaning 1.77 pounds per liter. Unfortunately, whereas the rest of the Air Canada fleet was calibrated for fuel quantity in pounds, the 767 used kilograms. 1.77 was a familiar number and the pilots did not think about whether it was pounds per liter or kilograms per liter. Disaster was avoided only by good luck and skilled piloting when the plane ran out of fuel in mid-flight.

(There are several slightly different versions of this story in different sources, so there may be minor errors of detail here. I don't have the official report of the flight, and it doesn't seem that anyone has scanned it onto the Internet.) --65.94.50.4 (talk) 08:30, 29 December 2014 (UTC)[reply]

Roughly speaking jet fuel has a mass of 0.8 kg per litre, or 6.7 lb/US gallon.It'll vary a little with temperature and scarcely at all with pressure. Any of the apparently erudite opinions expressed above that differ significantly from this are wrong.Greglocock (talk) 10:12, 29 December 2014 (UTC)[reply]

Clearly a 5% change in volume due to temperature between a standard day at sea level and "normal cruise altitude" is not going to confuse the pilot or the flight computers, and all Technical Orders and Manuals issued for the F-5 and F-16 are wrong. Got it.

There are reasons - as outlined higher up - why military aircraft measure fuel by mass and not volume, and I'm assuming the same reasons apply to airlines which also experience large changes in ambient temperature. WegianWarrior (talk) 10:54, 29 December 2014 (UTC)[reply]

The relevant temperature variations are those occurring on the ground and affecting the fuel before it is pumped into the aircraft. Temperature variations at cruise altitude are not relevant because, by then, the fuel has been loaded. The fuel gauges on the flight decks of large aircraft are calibrated in pounds (or kilograms), not gallons or litres.

If the pilot of a large airliner orders 15,000 pounds of fuel the refueler must divide that number by the density of the fuel in the underground tanks in order to determine the number of gallons (or litres) of fuel to be pumped into the aircraft. The density of the fuel will vary according to the temperature of the fuel in the tank, but will also vary slightly depending on the chemical composition of the fuel. Dolphin (t) 11:39, 29 December 2014 (UTC)[reply]

Which part of 'roughly speaking' isn't in your dictionary WegianWarrior? Greglocock (talk) 23:44, 29 December 2014 (UTC)[reply]

Note that the long-range versions of the Boeing 747 have a fuel capacity of about 240,000 L. A 5% change in volume (as when fuelling at a warm-weather versus a cold-weather airport; think winter service between Honolulu and Chicago or Minneapolis) is a difference of 12,000 liters, which is about 10 tons of fuel in round numbers—and also about what the jet burns in a hour of flying time: [15]. It's also probably pretty close to the total amount of reserve fuel the aircraft is required to carry: [16]. So while it is true that density only varies 'a little' with temperature, it's definitely enough to matter. TenOfAllTrades(talk) 17:19, 29 December 2014 (UTC)[reply]

Hey guys! Look what I found! A reliable and encyclopedic reference: the Weight and Balance Handbook, part of the series of free aviation training textbooks made available at no cost by the United States' Federal Aviation Administration. There's an entire chapter on fuel weight. Large aircraft (above 12,500 pounds, including most commercial jets) tend to measure fuel loads in pounds or kilograms. Small piston planes tend to measure their fuel loads in gallons, and the pilot must manually crunch numbers to ensure the aircraft is safely loaded.

I sincerely hope no aviators take heed of the rampant and uninformed speculation that has proliferated earlier in this discussion. Nimur (talk) 16:47, 29 December 2014 (UTC)[reply]

The amount of chemical energy in a given mass of fuel is a constant - irrespective of pressure, gravity, temperature or whatever. Measuring the weight of some amount of fuel is a reasonably close (and practical) way to estimate the mass of the fuel because the force of gravity doesn't change all that much from one airport to another. This means that the weight of the fuel is a reasonably good measure of the energy content. The energy content determines how long and how far the plane will fly - and that's what really matters. Hence they dispense fuel by weight, not volume.

In the case of your car, you buy fuel by volume - and this turns out to be a really, REALLY stupid idea. If you buy a gallon of gasoline when it's cool, you'll be able to drive further than if you bought a gallon of the exact same formulation from the exact same gas station when it's hot. Since what you care about is how far you can drive - and not how much volume of gasoline you have - it makes zero sense to sell the stuff by the gallon. There has been much controversy about that here in Texas where the weather gets hot and the gasoline manufacturers are (in effect) charging more for their product than they should. It's been argued that gasoline pumps could easily be equipped with a thermometer to measure the fuel temperature as it's dispensed and have the price of a gallon of gasoline be dynamically adjusted accordingly.

I've seen several sources recommending that you develop the habit of buying fuel on your morning commute (when the weather tends to be cooler) rather than on the way home. That's because you get more energy for your money if you buy it when it's cooler. I'm kinda skeptical that it makes a significant difference because the fuel is held in huge underground tanks and the temperature probably doesn't track the ambient air temperature very closely. Better advice is to not refuel until you absolutely need to...the additional energy required to haul 100 to 200lbs of gasoline around is significant and you'll use less fuel if your car (including fuel) weighs less.

In the case of an airplane, the amount of energy content in the fuel is just as important - but the weight of the fuel also alters the weight of the plane - and that's rather important for the pilot to know, so knowing the number of gallons he has on board isn't very interesting...it's the number of pounds that determines both how long he can keep flying and how he has to configure the aircraft during landings and takeoffs.

SteveBaker (talk) 16:57, 29 December 2014 (UTC)[reply]

I'll note that in some places – including Canada – gasoline pumps can account for density changes with temperature, and charge for a corrected volume of fuel: [17]. TenOfAllTrades(talk) 17:19, 29 December 2014 (UTC)[reply]

Virtually all commercial airlines will use weight. They have a maximum takeoff weight and a maximum landing weight. Jet A I thought was about 7 lbs per gallon while water is 8 lbs per gallon and gasoline is 6 lbs per gallon. whether fuel burn is measured in gallons or pounds per hour, the only meaningful quantity is how many pounds are on the plane at landing as landing weights can be much less than takeoff weights. --DHeyward (talk) 05:41, 31 December 2014 (UTC)[reply]

Thanks, all. Joseph A. Spadaro (talk) 17:04, 31 December 2014 (UTC)[reply]

Lichen and moss identification

Can anyone identify these species? The lichen looks like the picture of cladonia chlorophaea in Plants of the Pacific Northwest by Pojar and MacKinnon p.501, but the entry mentions that there are a number of similar species and I was hoping to narrow it down. Given the tip on each sporophyte on the moss, I'm guessing twisted ulota (p.476) but the pictures of the mosses in the book are at higher magnification than I can get with my camera, so I'm very unsure of this one.--Wikimedes (talk) 05:34, 29 December 2014 (UTC)[reply]

I get the distinct impression it's crawling over the wall, like in The Blob (and I suppose it is, on a time lapse movie). StuRat (talk) 06:08, 29 December 2014 (UTC) [reply]

Hemorroids!

The hemorrhoids article is unclear. It seems to start off suggesting that a hemorrhoid is a normal physiological structure that can sometimes develop abnormalities. Then it seems to suggest that a hemorrhoid is an abnormality. My attempt to reconcile this contradiction in the context of my limited prior knowledge is that in medical terms a hemorrhoid is a normal physiological structure which is referred to as an abnormality by the layman (leading to the ambiguity in the article). What's the situation actually? --78.148.105.13 (talk) 08:21, 29 December 2014 (UTC)[reply]

Haemorrhoids are swollen and inflamed veins around the anus. These veins occur as part of the normal anatomy of the anus but the acute or chronic inflammation or swelling of the veins which leads to discomfort, pain itching or bleeding is an abnormal pathology. The swelling and/or inflammation is usually caused by excessive pressure exerted on that part of the venous system which causes the veins to swell and ooze blood. Perianal itching occurs most commonly from inadequate personal hygeine which leave small amounts of faeces within the folds of the anus. Causes of increased pressure may be constipation leading to the need to strain, raised inter-abdominal pressure during later pregnancy or increased weight. [18]. Richard Avery (talk) 08:35, 29 December 2014 (UTC)[reply]

So would you agree that the first two sentences of the hemorrhoids article are misleading/inaccurate? If what you have said is correct, then hemorrhoids are inherently pathological which contradicts that part of the article, right? 78.148.105.13 (talk) 10:26, 29 December 2014 (UTC)[reply]

I agree that the opening paragraph needs rewriting and the phrase "pathological haemorrhoids" needs reviewing (I'm going to do it now) as it gives the impression that there are "non-pathological haemorrhoids". Richard Avery (talk) 10:56, 29 December 2014 (UTC)[reply]

Sidetrack: Where to discuss article improvement.

The place to discuss an inconsistency in the article is the talk page, Talk:Hemorrhoids. Robert McClenon (talk) 22:04, 29 December 2014 (UTC)[reply]

Poppycock. I could discuss it Costa Coffee if I want. It's not out of place here. I'd have a long wait for an answer on the damn article talk page and you know it. I might as well write my query with my finger in the sand as put it on that talk page. 78.148.105.13 (talk) 22:32, 29 December 2014 (UTC)[reply]

Issue discussed at WT:RDS#Hemorroids. -- ToE 02:28, 30 December 2014 (UTC)[reply]

Doc James has responded at Hemorroids#Edit with a link stating that the term "hemorroid" is used for the anatomical structure both in their normal condition and when inflamed -- ToE 12:09, 31 December 2014 (UTC)[reply]

Moment capacity of beam

Am I correct in thinking that the moment capacity of a beam has no effect on the bending moment distribution on it? 82.132.213.121 (talk) 15:21, 29 December 2014 (UTC)[reply]

I dont understand your Question. Moment capacity is an abilty and moment distribution sounds like an actual force. You have to add some link or detail to make sense. --Kharon (talk) 09:12, 30 December 2014 (UTC)[reply]

The crossing of a small female toy dog and a large male dog

In nature, speciation occurs when, say, two populations of the parent species cannot mate with each other in some way. In domesticated animals or animals in captivity, this can be a bit tricky, as humans can intervene in the mating process between a female dog and a male dog (or a female lion and a male tiger) or assist in the birthing process. This may suggest speciation occurs in animals in the wild, but there have been documented cases in which a wolf species successfully blends with the coyote species to form the coywolf species in the wild. Now what? Is this new hybrid species the opposite of speciation? In general, some hybrids are viable and fertile offspring of the parent generation, while other hybrids can't even be viable, let alone reach adulthood and mate naturally. In domesticated animals, I am wondering if it's possible to mate a large male dog (Newfoundland) and a small female dog (Toy poodle). I don't think viable puppies should be the size of the mother, because that would certainly suffocate the life out of her. In that case, are Newfoundlands and Toy Poodles different species, or are they considered the same species merely because they share the same ancestral lineage to the wolf? 71.79.234.132 (talk) 16:30, 29 December 2014 (UTC)[reply]

Domestic dogs are all the same sub species Canis lupus familiaris- See our article Dog breed. Two quotes from the article: "Dog breeds are groups of closely related and visibly similar domestic dogs, which are all of the subspecies Canis lupus familiaris, having characteristic traits that are selected and maintained by humans, bred from a known foundation stock" and "Dog breeds are not scientifically defined biological classifications, but rather are groupings defined by clubs of hobbyists called breed clubs". The only obstacles to breeding any dog breed with another are the practical ones of differing size etc. You could, however, artificially inseminate a Newfoundland bitch with the sperm of a toy poodle dog and produce offspring. The results of crosses between different breeds are called Mongrels. Richerman (talk) 17:16, 29 December 2014 (UTC)[reply]

Why do domesticated animals get an exception? 71.79.234.132 (talk) 17:23, 29 December 2014 (UTC)[reply]

Domestic animals do not get an exception. Richerman wasn't saying that. Both you and Richerman were referring to the practical issue of size. What is extremely unusual about Canis lupus familiaris is the extreme range of sizes in what is still, in the DNA, a single subspecies. The size problem is unlikely to be observed in non-domesticated species that do not have breeds with a weird range of sizes. As noted below, see species problem, as this is a special species problem. The breeds, which are the same subspecies in the DNA, can conceive, but the size difference is likely to be problematic with a small female and large male. I don't know what the experience of breeders is, although breeders may not care, because they try to maintain purebred species. I don't know what the experience of veterinarians is with size-discrepant mongrels. Robert McClenon (talk) 22:28, 29 December 2014 (UTC)[reply]

See ring species. Also note that humans are in the same situation as dog breeds, as a very tall male human and a very short female probably couldn't have normal childbirth. However, the fact that a midget male and giant female can breed makes it not quite a ring species, in both cases. StuRat (talk) 17:59, 29 December 2014 (UTC)[reply]

I mostly disagree as to Homo sapiens. The size range in H. sapiens, which is not the result of breeding, is no greater than other species, so that the problem of large fathers and small mothers is probably present in other mammalian species. H. sapiens does have a special problem, however, which is that full-term infants are at the limit of carrying capacity of their mothers, and some births are problematic due to cephalopelvic disproportion. That is because human babies have (and must have) large heads in order to start to learn human knowledge immediately after birth. Some other species have other special problems, such as giant pandas are too small. Robert McClenon (talk) 22:28, 29 December 2014 (UTC)[reply]

It sounds like you agree with me. Specifically, if human mothers are already at the limit in normal circumstances, a large baby and small mother can easily push them past that limit. StuRat (talk) 01:06, 30 December 2014 (UTC)[reply]

See also species problem. Richerman (talk) 18:16, 29 December 2014 (UTC)[reply]

There's an old joke: "I crossed a Great Dane with a Chihuahua." "What'd you get?" "A dirty look from the Chihuahua!" However, googling the subject yields examples of success with such cross-breeding. ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:17, 30 December 2014 (UTC)[reply]

I would have said "Well, the chihauhau was definitely cross with me !" StuRat (talk) 03:28, 30 December 2014 (UTC) [reply]

This is a matter of physiology, and has very little to do with species problem, and absolutely nothing to do with ring species like similar sized gulls or herps per se. μηδείς (talk) 02:05, 1 January 2015 (UTC)[reply]

Question about contraception--Can RISUG/Vasalgel theoretically fail?

I have heard about this contraceptive for a while by now, including how it has apparently been 100% effective in clinical trials so far; thus, my question here is this--can this contraceptive theoretically fail? I myself am guessing that the answer to this question is Yes, but I am wondering as to what all of you think about this.

Also, for reference: Reversible inhibition of sperm under guidance

Futurist110 (talk) 18:41, 29 December 2014 (UTC)[reply]

You've been here for long enough to know you shouldn't be asking what we think of anything. However in terms of the general question of failure rates, the article doesn't give any reasons to expect things will necessarily be better than Vasectomies which do have a non zero failure rate. Nil Einne (talk) 19:30, 29 December 2014 (UTC)[reply]

Maybe I should have phrased this better, but what I meant was if anyone here would be able to utilize his or her knowledge on this to try answering this question of mine. Futurist110 (talk) 06:23, 30 December 2014 (UTC)[reply]

Reading a bit more [19], it sounds like the early failure rate could be significant lower. However it's less clear for the late failure rate, and still no particularly reason to think it will be definitely zero (even with a medical procedure there's still the human component of the doctor as of now). The source also mentions a non surgical reversal method and while it sounds like something unlikely to occur accidentally (but people do have a lot of different sexual preferences), it may not always be necessary to go to such a level for reversal. P.S. To be clear, when I say "it" above, I'm actually thinking of the overall failure rate rather than just the late failure rate. My point is that the early failure rate may be significantly lower than a vasectomy, for reasons given in the source, the info given is insufficient to even suggest the late failure rate will be significantly lower nor to suggest that the overall failure rate will be zero. Nil Einne (talk) 19:36, 29 December 2014 (UTC)[reply]

Thank you for this info; also, I've got a question--can a male's body theoretically reject and/or expel this injection (before 10 or 15 or whatever number of years are up)? Futurist110 (talk) 06:23, 30 December 2014 (UTC)[reply]

No particularly reason to think it will never happen. Nil Einne (talk) 13:48, 30 December 2014 (UTC)[reply]

Reversible_inhibition_of_sperm_under_guidance#Advantages says that 1 of 250 test subjects did have an unplanned pregnancy as a result of improper placement. So, including this in the mix, we get a 0.4% failure rate. However, I suspect that the medical personnel administering this method in a test environment would be better trained than average, were this to go into wider use. So, the human error rate might go way up. StuRat (talk) 19:48, 29 December 2014 (UTC)[reply]

Can't one make sure that the doctor performed this procedure correctly afterwards when one goes/returns to the doctor's office for a check-up, though? Futurist110 (talk) 06:23, 30 December 2014 (UTC)[reply]

Well if you read our article, it does discuss Smart RISUG, and also link to the source (from 2009) discussing this concept of adding iron oxide and copper particles to make visualation with x-ray and magnetic imaging easier. I would suspect it would probably show up under x-ray even without the additions, but x-raying the male gonadal area may not be ideal if you're looking for reversible contraception and I guess the additions probably increase the contrast or allow a lower dosage. Don't know about MRI without the additions (well I presume they mean MRI), I'm actually a bit surprised it's okay to use this after the additions of iron oxide and coppper but I guess the quantity is low enough that it's safe. In any case, the source does seem to suggest Smart RISUG is important to enable easier testing and does mention contrast. But Smart RISUG seems even less tested than the others, actually I can't find any further followup since 2009. Of course an MRI isn't exactly cheap anyway. Nil Einne (talk) 13:48, 30 December 2014 (UTC)[reply]

The iron oxide is funny. If you tell somebody your balls are full of rust, they might assume you haven't had sex for a very long time. StuRat (talk) 15:47, 30 December 2014 (UTC) [reply]

Looking at the article - I assume (and hope) they apply the radiation to the polymer _before_ it's been injected? 300 rads to your intimate bits in 10 seconds will be very effective in preventing reproduction, and, indeed, respiration. I think some clarification of the article is in order. Tevildo (talk) 20:45, 29 December 2014 (UTC)[reply]

December 30

Can a dog's toe cut off when cutting nail?

When cutting a dog's nail, can a person cut so far beyond the quick (or kwik) that the bone is cut off or part of the bone is cut off?174.3.125.23 (talk) 02:32, 30 December 2014 (UTC)[reply]

I suppose so, as long as the tool can open wide enough. However, you'd need to be seriously incompetent to do that. That's a bit like accidentally cutting off an ear when cutting hair. StuRat (talk) 03:25, 30 December 2014 (UTC)[reply]

The word "quick" literally means "alive", and cutting that part of the dog's claw can cause it great pain, bleeding, and necessitate a trip to the hospital. I am not quite sure what anyone would be doing cutting the claw to the quick, not to mention beyond. μηδείς (talk) 19:00, 30 December 2014 (UTC)[reply]

A decade or two ago (when my family had cats) I remember reading in cat magazines that the process of declawing (which for cats is/was rarely performed in the UK and is now illegal, but apparently is/was used more elsewhere) involved the deliberate removal of all or part of the end bone on each toe. Presumably this could also be applied to dogs deliberately, and an incompetent claw-clipper could presumably do this accidentally. {The poster formerly known as 87.81.230.195} 212.95.237.92 (talk) 14:27, 31 December 2014 (UTC)[reply]

Which part(s) of North America has/have a climate most like New Zealand's?

Just curious. It's a big place with a lot of variation in climate, so I figure there's probably at least one region where it's reasonably similar to NZ. --203.96.145.52 (talk) 05:57, 30 December 2014 (UTC)[reply]

There will be many places in the US that match one or two aspects of New Zealand's climate. For example, there will be many places whose rainfall matches the rainfall in certain places in New Zealand; there will be places in the US whose winter minima match the winter minima in certain places in New Zealand. But New Zealand is a small island and the US is a continent so I doubt there is any place in the US whose climate throughout the year is close to the climate throughout the year in some place in New Zealand. Dolphin (t) 06:06, 30 December 2014 (UTC)[reply]

The US has lots of islands, including the Hawaiian Islands (probably too warm) and the Aleutian Islands (probably too cold). There are many islands in between, like Catalina, Block Island, and Long Island, so you should be able to find one that matches parts of NZ fairly well. This islands around Seattle might be a good match. There's also Vancouver Island just across the border in Canada. StuRat (talk) 20:14, 30 December 2014 (UTC)[reply]

NZ may be small, but I'd say that the variation in climate for NZ is so large as to render the question meaningless. East coast is dry, west coast is very wet. North of the north island is as warm as sydney, south of the south island is a tad chilly. Greglocock (talk) 06:28, 30 December 2014 (UTC)[reply]

Climate classification schemes can give you one answer. The most commonly used scheme is the Koeppen classification. The most populated parts of New Zealand have a Cfb climate in this scheme, which is not found to any significant extent in the U.S. Other places with Cfb climate include northern and western Europe. As Greglock notes, climate across New Zealand is rather variable so this does not apply everywhere in that country. Short Brigade Harvester Boris (talk) 16:36, 30 December 2014 (UTC)[reply]

The temperate rainforests of the West Coast of New Zealand should be similar to some of the Pacific temperate rainforests, being at similar latitudes and both being rain forests.--Wikimedes (talk) 19:41, 30 December 2014 (UTC)[reply]

how does previously boiled water differ?

Preparation instructions on something call for 'cold boiled water (you can use spring water)'. Huh? Why - how does the fact that water has been previously boiled change it? Why doesn't it just say 'cold water'? (And it definitely calls for cold water, not water you bring to a boil from a cold status, which I thought might be a reading for 'cold boiled water.' I know this both due to the fact that it's a cold meal and also the fact that the translations don't call for boiling.) By the way this is like two sachets of a powder you mix into a pudding, and like oats or granola, respectively. the product is this one: http://www.mokate.eu/our-brands,yogocrunch,205.html 212.96.61.236 (talk) 07:39, 30 December 2014 (UTC)[reply]

Previously boiled pure water is no different from unboiled water, chemically or physically. Plasmic Physics (talk) 08:07, 30 December 2014 (UTC)[reply]

This sounds like an instruction to reduce the amount of air suspended in the water, which is what will happen if you boil it or use bottled water rather than tap water. I couldn't find any reference to "cold boiled water" in the above link. What is it that is being prepared? Can you point to an example of this instruction in context?--Shantavira|^{feed me} 08:25, 30 December 2014 (UTC)[reply]

Yes, PP's pure water is rare outside the laboratory, so there is a minor difference in that boiling releases nearly all the dissolved air in tap water. I can see no reason why dissolved air would be a problem in the preparation. Dbfirs 08:34, 30 December 2014 (UTC)[reply]

Boiling tap water can also lower the concentration of any minor disinfection by-products that result from treatment processes, which could otherwise interfere with food preparation chemistry. Plasmic Physics (talk) 09:04, 30 December 2014 (UTC)[reply]

Yes, it will get rid of any volatile contaminants, but might concentrate others. It doesn't get rid of the "chlorine taste" that I notice in most UK tap waters. (I'm not sure what residue this is -- obviously not chlorine gas.) Dbfirs 09:43, 30 December 2014 (UTC)[reply]

So regarding what it is, the product is a pudding (that you mix cold by adding 100 ml of water and mixing well), and then after mixing you mix in the other packet, which is a much larger packets of oats or granola or something, to make a delicious quick thing that I wanted to describe as a parfait. (But I guess this word is wrong, and parfait must have frozen ice cream etc.) There are pictures on the front of the packaging in my earlier link.

Returning to 'cold boiled water', here are thousands of pages with the words "cold boiled water" and pudding, apparently all preparation instructions: https://www.google.com/search?q=%22cold+boiled+water%22+pudding Obviously pouring cold water is hundreds of times faster and easier than taking out a pot, pouring cold water into it, putting it on the gas, turning on the gas, waiting for it to boil, removing it from heat, and waiting for it to cool down again all the way to cold status. (I mean literally hundreds, if not thousands, of times faster - a tenth of a second versus ten minutes. In the case of this preparation for example, waiting for the boil and cooling down would be 90% of the preparation time. So unless there is some use, I doubt it would make it into these otherwise quite simple recipes. The product in question is also particularly simple and convenient. There must be some chemical reason. 91.120.14.30 (talk) 10:03, 30 December 2014 (UTC)[reply]

If the British can make parfait of liver and the Americans can use yogurt, I think yours is as valid. Rmhermen (talk) 15:42, 30 December 2014 (UTC)[reply]

The usual reason for boiling water before use and allowing it to cool is to kill any bacteria it may contain. Sugary foods made up with cold ingredients (or made with hot ingredients and allowed to cool) and then left to stand for a while, are a very good medium for growing bacteria, so you want to start off with a minimal amount of bacteria present. Babies are given cooled boiled water for the same reason. Richerman (talk) 10:45, 30 December 2014 (UTC)[reply]

I can see the reason for boiling water for young babies whose stomachs may not be sufficiently acidic to kill bacteria, but most tap water in the civilised world contains only a few relatively harmless bacteria, and the food (or the boiled water), if left uncovered, it will gain a greater number of bacteria from the air. Can bacteria be the only reason for the recipe? Dbfirs 12:28, 30 December 2014 (UTC)[reply]

This is not convincing at all. Why would packaging for something I prepare and eat in 5 minutes care in the slightest whether my tap water contains some bacteria? What, is the pudding such a potent agar that in 5 minutes any bacteria present in tap water would multiple by a trillion? Why doesn't it ask me to treat it with sterile gloves then? Since the product is intended for adults, this explanation is completely unconvincing. Nothing else you mix with water mentions this. 91.120.14.30 (talk) 14:34, 30 December 2014 (UTC)[reply]

There's probably a customer service number on the package somewhere; you could call them and ask. You could also prepare it both ways, and see if you notice a difference in taste, texture, etc. If you do either of these, it would be a kindness to write back here and tell us what they said (or what you discovered). My only contribution to the guessing game is: is it possible this is intended for camping, or some other use where the quality of the water would be suspect? --Floquenbeam (talk) 14:43, 30 December 2014 (UTC)[reply]

That's an excellent guess! (camping). Sure, if I figure it out I'll tell you. For what it's worth I had ignored the silly suggestion, used cold water, and it tasted fine. But one thing is - what do you make of all the Google links I showed showing the presence of this phrase in recipes? (and you can remove 'pudding' from it and get different recipes.) It certainly must have some effect. I think the earlier guess of removing dissolved air was a good one. 91.120.14.30 (talk) 15:21, 30 December 2014 (UTC)[reply]

Worth noting the pudding in question appears to come from Poland. From various searches, it appears that it may be common that water from the tap there is perceived as unsafe. To be clear, I'm not saying it is unsafe but rather than it may be a common perception by locals, so bottled or boiled water is commonly used even just for drinking. This isn't particularly uncommon, e.g. from what I can tell it may be the same in the Czech Republic (where I mistakenly originally though the pudding was from) or in Malaysia (there is perhaps a bigger question over the water quality there but I suspect it is safe, at least in terms of anything that boiling would help with in urban areas).

Of course it isn't normally necessary to say "cold boiled water", locals will already guess what to do. One possibility is the manufacturer may want to encourage the use of tap water rather than bottled water considering it harmful to the environment or something, from what I can tell bottled water tends to be used for drinking more than boiled water although I don't know what's used in uncooked food preparation. Alternatively, if the instructions you're referring to are in English, it maybe the manufacturer (or rather whoever was writing the instructions) doesn't really think of tap water as ever really safe and wanted to make sure their English speaking customers didn't do dumb stuff. (I can say when I first came to NZ, I found drinking water directly from the tap weird. I found the same when I went to Singapore than Malaysia and once tried the same, even though I'm even more convinced the water there is safe.) A final possibility is that the manufacturer is ultra set in the belief tap water is unsafe and wanted to warn even Polish people to use boiled water (I think it's sometimes true people wouldn't think of drinking water straight from the tap, yet will blindly use it in food prepration even when the food is uncooked and they're drinking a lot of it).

As for the search results, well many of them look to similarly be stuff written by people from places where there may be the same perception. Also, in terms of my earlier point, puddings, cold drinks and powdered milk are a few of the cases where you may use a fair amount of water in food preparation which will be consumed in without heating so for people with such a perception it's somewhere it's likely to come up. (It also comes up with ice, but there the water doesn't have to be cooled before.) I have seen milk powders with a more nuanced warning (suggesting you used cold boiled water if you aren't sure of the water safety).

Nil Einne (talk) 17:35, 30 December 2014 (UTC)[reply]

Some thoughts:

1) Let water sit to improve the taste. This let's volatile chlorine related compounds evaporate. I suggest leaving it in the fridge in a sealed glass bottle overnight. (The glass prevents chemicals from leaching into the water from a plastic container.) Any food made with such water may taste better than fresh tap water.

2) Lawyers often require frivolous warnings. Consider that if somebody leaves the parfait out for a day and then eats it, and dies as a result, the lawyers suing the company might argue "If only they had said to boil the water first, then the bacteria count would be so low to start, that it wouldn't have grown to a fatal level by the time it was eaten". This is why Q-tips contain a warning to never put them in your ear, even though that's the only reason to put a cotton ball on the end of a long stick in the first place. StuRat (talk) 17:50, 30 December 2014 (UTC)[reply]

There are plenty of uses for cotton swabs besides the silly usage of sticking them in your ears. Manufacturers presmuably know this is the most common usage, but beyond the question of whether they should, it's also unclear what they could do to stop such misuse. Nil Einne (talk) 18:14, 30 December 2014 (UTC)[reply]

The obvious answer is to sell cotton balls instead. Can you think of any reason the cotton needs to be on a stick, other than to fit in the ear ? StuRat (talk) 18:43, 30 December 2014 (UTC)[reply]

Yes, actually. Cotton swabs can be used for applying liquid or powder to a surface (makeup, ointment, or a cleaning solution.) A tiny cotton ball on a stick allows you finer control in applying it, and keeps whatever you are applying off your fingers.--Srleffler (talk) 09:05, 31 December 2014 (UTC)[reply]

ObPersonal: another use is to apply clove oil to a sore tooth or gum (it tastes foul, so you don't want to be splashing it around your mouth too indiscriminately). {The poster formerly known as 87.81.230.195} 212.95.237.92 (talk) 14:34, 31 December 2014 (UTC)[reply]

Indeed, StuRat's comment is just weird. Even if you really can't imagine other uses for cotton buds despite having lived until adulthood with all the life experiences and seen and used the cotton buds for some purpose (even if it is just cleaning your ears), one would have thought you can imagine why it would work better in some cases for some of the uses mentioned in our article (which I presume was read before asking the question). Still if StuRat is still unable to imagine, they could tell all these people they're doing it wrong and should use cotton balls instead [20] [21] [22] [23] [24] [25] [26] (comment only) [27] [28] [29] [30] [31] [32] [33] [34] [35] (probably described in video but not shown, is in description though) [36] (they use cotton buds & cotton balls for related purposes, n.b. the purpose isn't for application!) [37] [38] [39][40]. (Okay the last 3 or so are a bit weird.) Of course this is ignoring speciality cotton buds like those mentioned in our article or [41] which may not imply a usefulness for ordinary cotton buds, but do speak to there being a usefulness for having a cotton bud or cotton on a stick compared to cotton balls. (N.B. I didn't check carefully enough that all the previous uses were ordinary cottons buds although they were shown in the videos except perhaps for the fishing one and the one without video and where noted.) Nil Einne (talk) 18:53, 31 December 2014 (UTC)[reply]

For anyone else confused by the term "cotton bud", it's apparently British English for what Americans call a cotton swab, or a Q-tip. StuRat (talk) 20:05, 31 December 2014 (UTC) [reply]

What is the difference between adverse reaction and side effect?

185.13.195.173 (talk) 13:45, 30 December 2014 (UTC)[reply]

I'm not a doctor, but how I would understand the terms as a layperson, is that an adverse reaction is unusual, unexpected and specific to a person. For example, you could be allergic to the medicine! you have to completely stop taking it, you react very badly to it. You're reacting quite badly to the medicine itself. Whereas, 'side' effect, as the name implies, is secondary. It could even apply in 100% of cases - a side effect of caffeine pills is that you will urinate more as it's a diuretic. It's a side effect because nobody cares about it, it has nothing to do with the reason for the bill. it's not the primary effect. I hope this shows most of the connotations. 91.120.14.30 (talk) 15:45, 30 December 2014 (UTC)[reply]

Yes, side effects can be positive. For example, it is claimed that a 2012 review of seven studies published in the journal Breast Cancer Research and Treatment showed that metformin [prescribed for diabetes] is also linked with a 17 percent lower risk of breast cancer. (Disclaimer: example for illustration only; I don't know how accurate this claim is.) Dbfirs 16:39, 30 December 2014 (UTC)[reply]

A good (and uncontroversial) example of a beneficial side effect is Viagra, which was originally intended to treat high blood pressure. Tevildo (talk) 17:12, 30 December 2014 (UTC)[reply]

Side effect is the more general term, and it usually connotes expected and mild symptoms like drowsiness from an antihistamine that do not cause a doctor to discontinue the prescription. Adverse effects are rare, severe, and possibly life threatening side effects like allergic reaction, anaphylaxis, and liver damage that cause one to stop using the medicine. Here is some basic info from the US FDA. Note that many of the supposed side effects you hear or see in drug commercials in the US are not really side effects, but any symptom that is reported by those using the drug, like sleepiness or insomnia for sleeping pills, and "delayed back ache" for Viagra (in other words you had sex that was too vigorous). See also, Happy Fun Ball. μηδείς (talk) 17:23, 30 December 2014 (UTC)[reply]

I've also seen "side effect" used to describe the main effect. For example, insulin came with a warning that it may cause low blood sugar. StuRat (talk) 17:54, 30 December 2014 (UTC)[reply]

Yes, this is due to the changes in FDA regulations in the 90's at the same time they started allowing things like melatonin to be sold as "food supplements". Basically, any effect reported over a specific statistical threshhold will be mentioned, like a stool softener causing diarrhea. Then they will mention the "rare side efects" which are important because they are clinically serious, like "priapism". Then they will mention things like, if you stop breathing, cease taking your one-a-day pill and call a doctor, as if you'd take a second pill or be able to call your doctor. See this commercial contemporaneous with the change in FDA regulations.μηδείς (talk) 18:46, 30 December 2014 (UTC)[reply]

Graph Axis labels

When labelling graphs, why do some people say it's incorrect to put units in brackets. For example, "time (s)". They claim the correct label is "time /s". 176.251.149.108 (talk) 14:56, 30 December 2014 (UTC)[reply]

A graph is just a way to communicate information. If it clearly and accurately communicates the information to the reader, then it succeeds in doing its basic job. All else is just "style". Labeling an axis with quantity/unit is just one way of stating what the quantity and unit are. It might have some mathematical elegance to it: quantity/unit is dimensionless, matching the unit-less labels on the graph, but this does not do anything more or less than an equivalent textual description. Insisting that there's only one correct way to do it is, IMO, just stubbornness. --98.114.98.174 (talk) 15:45, 30 December 2014 (UTC)[reply]

While I don't disagree with all of what 98 said, following standard mathematical/algebrical convention seems to be the main rason some sources including the SI recommend using /s rather than (s) [42] [43] Nil Einne (talk) 16:53, 30 December 2014 (UTC)[reply]

The first of those links, the BIPM document, does not specifically recommend this style over others; it just says it's permissible. However, its author seems to think that the only legitimate alternative is to repeat the unit explicitly on each tick. The alternative mentioned by the original poster, "Time (s)", is not even mentioned. --65.94.50.4 (talk) 18:57, 30 December 2014 (UTC)[reply]

Parentheses are often used to indicate an alternate unit, so it might say "Speed m/s (ft/s)". StuRat (talk) 17:56, 30 December 2014 (UTC)[reply]

We are not talking about "alternate units". --65.94.50.4 (talk) 18:57, 30 December 2014 (UTC)[reply]

Yes, but consistent usage of parens means you would only use them when you have alternate units. StuRat (talk) 20:18, 30 December 2014 (UTC)[reply]

I imagine the pointy heads are trying to claim that a graph is a plot of numbers, and so they are non dimensionalising the measurements to numbers by dividing by the units. As someone who works with data for 50% of the week, i'm just glad when the units are mentioned. I'd add that if the pointy heads were really doing it properly they'd be plotting dimensionless variables, such as Re, otherwise they are kidding themselves, there is still an implicit assumption about which system of units they are working in. Greglocock (talk) 20:12, 30 December 2014 (UTC)[reply]

If the quantity being graphed is time, and is measured in seconds, "/s" could be confusing, as the "/" sign suggests division, i.e. s^-1, which is a unit of frequency. So I'd avoid the "/" sign as it introduces ambiguiety. --NorwegianBlue^talk 21:28, 30 December 2014 (UTC)[reply]

Yes the "/" sign does represent division: time divided by seconds yields a (dimensionless) number. There is a logic to the "/" convention, but the bracket notation is perfectly clear so it's pedantic to object to it. --catslash (talk) 23:20, 30 December 2014 (UTC)[reply]

But it is also pedantic to do it. For instance suppose I label my axis 'speed /mph' on one graph, and 'speed /kph' on another. The actual numbers I plot are different so the pointy head argument fails. What I should do is plot 'speed /c' and then it doesn't matter what units I am working in, 'c' being the speed of light.Greglocock (talk) 20:51, 31 December 2014 (UTC)[reply]

That's just changing units. If you keep the mph and kph you'd still have different numbers even if you divide by "c". If you want the graphs to be easy to compare, you would need to plot something like speed/max speed (or percentage of maximum speed). (If you need to compare graphs, then the logical thing is to use the same units on both, of course.) Dbfirs 21:14, 31 December 2014 (UTC)[reply]

Asphalt question

What is the main difference between the asphalt used on high speed roads and those used on city roads? — Preceding unsigned comment added by 176.251.149.108 (talk) 19:16, 30 December 2014 (UTC)[reply]

“main” is a bit subjective. From Alaska to California there are different conditions to be taken into account. See if Asphalt concrete goes to answering your inquiry.--Aspro (talk) 20:09, 30 December 2014 (UTC)[reply]

Some roads have different base course, pending on vehicles weight to prevent ruts. A higher load for the road occurs at stop points. --Hans Haase (有问题吗) 20:20, 30 December 2014 (UTC)[reply]

My dad having been a civil engineer, thinks that the main difference is that high speed roads are constructed using higher grade asphalt, graded according to the Marshall stability system. This system rates the viscosity. Higher traffic flow also calls for a thicker asphalt layer. Plasmic Physics (talk) 21:16, 30 December 2014 (UTC)[reply]

why does it need to be thicker and more viscous? 176.251.149.108 (talk) 00:45, 31 December 2014 (UTC)[reply]

I'm just guessing here, but since asphalt is a Newtonian fluid, the higher vehicle speeds cause higher shear stresses. Therefore, the road surface deforms faster. Using a more viscous asphalt, means that it can handle higher shear stresses. Newtonian fluid dynamics. Higher traffic flow just means that the road wears out faster, meaning that a thicker layer makes it last longer. Plasmic Physics (talk) 04:50, 31 December 2014 (UTC)[reply]

Is it? I thought asphalt is viscous-elastic or shear thinning. 82.132.244.201 (talk) 13:47, 31 December 2014 (UTC)[reply]

Being a Newtonian fluid was part of the guess. My point is that the answer lies in the rheology of the asphalt. Plasmic Physics (talk) 21:11, 31 December 2014 (UTC)[reply]

Also, a big problem with asphalt is that it breaks apart starting at the edges, so better edge protection might be in order. StuRat (talk) 21:24, 30 December 2014 (UTC)[reply]

Ah, “it breaks apart starting at the edges”. Is that why so many geriatrics stick to the middle of the highway with their cruse control stuck on 55 mph -like their trying to get back to the future?--Aspro (talk) 21:35, 30 December 2014 (UTC)[reply]

That would require 88 mph, and the only way they are likely to hit that is when they confuse the brake and accelerator pedals. :-) StuRat (talk) 22:42, 30 December 2014 (UTC) [reply]

Then they should just switch their speedometers to metric. 55 mph = just over 88 km/h. So there!--65.94.50.4 (talk) 01:36, 31 December 2014 (UTC)[reply]

Why did you guys switch to back to the future references? how did 'it breaks apart starting at the edges' prompt this? 212.96.61.236 (talk) 02:34, 31 December 2014 (UTC)[reply]

No idea why Aspro did, but I just followed his lead. StuRat (talk) 05:47, 31 December 2014 (UTC) [reply]

And in case you don't know, 212.96.61.236, the informal convention on the Ref Desks is to switch to small text when we're either telling jokes inspired by the main text but not pertinent to actually answering the Original Post(er), or pursuing a serious but equally irrelevant digression. {The poster formerly known as 87.81.230.195} 212.95.237.92 (talk) 14:41, 31 December 2014 (UTC)[reply]

I'm guessing Aspro is referring to the fact 55 mph is no longer the maximum speed thoroughout the US as it was at a time (National Maximum Speed Law), yet some people may still drive at that speed even in places where the current limit is higher. Nil Einne (talk) 19:32, 31 December 2014 (UTC) [reply]

Tell you this. If one of these geriatrics did hit the magical 88's, then they might find themselves back in 1885 with a Wells Fargo stage coach tailgating them instead of me, with the shot-gun yelling at them “Move over – you @% $Ж ** road hogs!” Rather than me sitting patiently going beep beep on my little horn, which they probably can't hear, because if they are not completely stone deaf, they are probable listening to something like Ride of the Valkyries at 331⁄3 RPM. Don't even try to tell me what that is equivalent to on shellac I DO NOT WANT TO KNOW! Mind you, having said that, Black Sabbath played backwards at the same speed was interesting.Black Sabbath played backwards. I think I would probably play safe and stay in the middle lane and away from those crumbly edges if I was listening to that.--Aspro (talk) 00:01, 1 January 2015 (UTC)[reply]

See also Rubberized asphalt which is sometimes used for noise reduction purposes. Alansplodge (talk) 17:37, 31 December 2014 (UTC)[reply]

December 31

Proper name for a wrench that works on smooth shafts and how it works

I came across this tool called a "feathering shaft wrench"[44]. Here's a video of how it works[45]. It's called a "feathering shaft wrench" in this particular scenario because it's a wrench used to grip the feathering shaft on RC helicopters, but the same mechanism is in use in other fields as well, e.g. in milling chunks[46]. I'm looking for the general name of this mechanism that's capable of griping smooth shafts.

Also, how does this thing work? (Normally I would just Google it to find out, but I can't find the name of this mechanism, hence my first question.) The shaft is perfectly smooth and contains no gripped flats, and there doesn't appear to be any gripping "teeth" on the wrench itself. If anything, the inside of the wrench looks exactly like a needle roller bearing. How does the wrench manage to grip the shaft? WinterWall (talk) 02:03, 31 December 2014 (UTC)[reply]

The wrench probably uses something like this: [47] (click on the 'How it works' tab). It uses needle rollers in tapered recesses - turning one way, the roller moves freely, but going the other way the taper forces the roller against the shaft. The manufacturer describes it as a 'roller clutch', though it may also have other names. AndyTheGrump (talk) 02:15, 31 December 2014 (UTC)[reply]

Thank you very much, Andy. WinterWall (talk) 02:25, 31 December 2014 (UTC)[reply]

Resolved

See also Sprag clutch. Dolphin (t) 00:00, 1 January 2015 (UTC)[reply]

See also, strap wrench. μηδείς (talk) 02:00, 1 January 2015 (UTC)[reply]

Implantable Fuel-Cell

Does anyone know of research that has been done into fuel cells that run on blood, and which could then be implanted for (obviously fairly small-scale) electricity generation? GoldenRing (talk) 02:20, 31 December 2014 (UTC)[reply]

Neither having burnt plasma nor burnt bloodcells would be worth the metabolic cost and likelihood of toxemia and liver and kidney failure. Is there some reason heel pumps in your shoes or a bicycle hooked to a generator wouldn't be preferable? μηδείς (talk) 03:02, 31 December 2014 (UTC)[reply]

Pure curiosity. It seems to me the mechanism ought to be able to eg extract glucose direct from the bloodstream and convert it to water+CO2. I'm not sure why that might induce toxemia or liver or kidney failure, though an auto-immune reaction might be a risk, I guess. GoldenRing (talk) 03:31, 31 December 2014 (UTC)[reply]

They do have a device that runs a watch based on body movements, so that might be a more practical way to power some kind of monitor device, if that's what you had in mind. StuRat (talk) 05:44, 31 December 2014 (UTC)[reply]

Alternatives would seem to be a better choice. Inductive charging and the technology for pacemakers would seem to be a better fit for small scale electrical generation. Pedometers and other motion related activity would be a second choice if it wasn't life safety. I doubt anyone would use blood as a primary source of energy for anything that was life safety. I personally would love to see a something that consumed calories and built muscle without exercise. --DHeyward (talk) 05:57, 31 December 2014 (UTC)[reply]

I'm with you there. We need to find a way to convince our bodies we aren't on the verge of starvation, and that all muscle doesn't need to be converted to fat the moment we stop moving. Besides us lazy folks, there's also weightless astronauts and the crippled/bedridden to consider. StuRat (talk) 06:04, 31 December 2014 (UTC) [reply]

I confess there was a certain amount of this, combined with the post-Christmas bloat, that set me thinking this way. GoldenRing (talk) 10:07, 31 December 2014 (UTC)[reply]

This has indeed been looked at intensively, usually using the glucose present in blood/CSF etc as fuel, just the first link I found: http://www.extremetech.com/extreme/130923-mit-creates-glucose-fuel-cell-to-power-implanted-brain-computer-interfaces. And Medeis, I don't know why you're talking about burnt stuff, you do realise fuel cells don't have to always run at elevated temperatures? Also, it is blatantly obvious why you would want to do this, rather than hell pumps or a bike, limitless power for implants. Fgf10 (talk) 10:50, 31 December 2014 (UTC)[reply]

By burnt I meant oxidized, not charred, and the OP specified blood, not glucose. Blood consists mainly of plasma and red blood cells. Since a cyclist burns glucose, I don't see what's wrong with pedalling a generator rather than risk having artificial implants that besides their mechanical disruption of the body might easily kill you by hypoglycemia if they malfunction. μηδείς (talk) 16:39, 31 December 2014 (UTC)[reply]

Well, why did you say burnt then? Anyway, where do you think the glucose comes from? The blood of course. The OP stated exactly that in their second post. Or where you thinking you can run something off plasma? You don't see what the advantage is of having an internal inexhaustible fuel supply rather than a vulnerable external supply with skin penetrations? Don't know what to say to that! Not sure if you're grasping what this is about. Fgf10 (talk) 17:25, 31 December 2014 (UTC)[reply]

I made the obvious mistake of assuming you were a high school graduate. Sorry. Nor does glucose "come" from blood, so I've obviously made multiple gross overestimations in regard to your education level. Terribly sorry. μηδείς (talk) 01:56, 1 January 2015 (UTC)[reply]

Techically you're right the proposed fuel cell in the paper proposes getting glucose from cerebrospinal fluid rather than directly from the blood, for various reasons mentioned in the paper. However as may be obvious the idea of getting glucose directly from the blood (as well as from interstitial fluid) is mentioned in the paper (otherwise they couldn't discuss the advantages of the CSF) so I'm fairly confused about your complaint even if I'm not Fgf10. Yes, in the linked paper the glucose for the fuel cell wasn't coming directly from the blood, but the idea of getting it directly from the blood is clearly there (although I personally wonder if getting it from interstitial fluid instead of direct may be better). In case there's still some confusion, it's worth noting that in both interstitial fluid and cerebospinal fluid, in most cases a very high percentage of the glucose will have been originated from transport via the blood (much more so in the later of course). P.S. In the case of brain implants, even if these won't use glucose directly from the blood in any case, it's probably even more significant whether you want an internal battery that needs to be replaced potentially with brain surgery, an external battery with the associated cabling etc (may also be used for a brain implant depending on internal battery location, inductive charging and any potential risks (which realisticly will also need a battery which may need replacement anyway), or these highly hypothetical but still researched ideas of a probably glucse fuel cell. Nil Einne (talk) 07:02, 1 January 2015 (UTC)[reply]

Yeah it's worth noting that even with pacemakers, the battery lifespan [48] [49] is 4-12 years. The surgery is more minor than implanting the pacemarker, still as you may guess from the earlier sources or [50], as surgery it's not without risks. Of course as sorted of hinted in the earlier sources, some people may welcome the battery running out [51] [52]. Still it would seem that for some, not having to run the risk of the replacement may be better, presuming that such powering methods could ever be as reliable and safe (which may be a big if). It may be that by the time such methods become available (if ever), there are batteries which can last long enough, say 50 years, that battery replacement is unlikely to be a concern for pacemakers. And there are other alternatives for some other implants [53]. Still it's easy to imagine even these may not be enough, particularly for recreational or perhaps non essential monitoring implants (as mentioned by StuRat). Worth remembering if having the latest iPlant (or maybe Apple Imp/Apple Implant) if the current CEO stays around) isn't appealing to you (as it isn't for me), you're probably not the best source for what people find acceptable if they are quite interested. Nil Einne (talk) 19:15, 31 December 2014 (UTC)[reply]

What is the reason for the changes between the right and left valves in the heart?

Why is there in the right side triquspid valve (made of three) while in the left there is biquspid valve (made of 2)? Is there any explanation for that? 5.28.189.173 (talk) 15:36, 31 December 2014 (UTC)[reply]

The correct spelling is tricuspid valve and bicuspid valve (which is more commonly called the mitral valve). I'm not sure of the reason, but the mechanical factors affecting each valve are different, because the right side of the heart only pumps blood to the lungs (for oxygenation), whereas the left side pumps it to every other part of the body. Looie496 (talk) 16:27, 31 December 2014 (UTC)[reply]

Why dont things stay floating in the air

Why do things fall to the floor? If I put a piece of metal into a pool with plastic balls with much lower density it remains on the top of the balls, so, what is happening here? Lower density does not explain it completely.— Preceding unsigned comment added by Nntt21 (talk • contribs) 19:37, 31 December 2014 (UTC)[reply]

Buoyancy, or more specifically negative buoyancy. Short Brigade Harvester Boris (talk) 19:46, 31 December 2014 (UTC)[reply]

As for why a heavy object can balance on lighter objects, that has to do with the heavier object's center of mass being between the lighter supports, which makes it stable. However, the situation you described sounds like the lighter balls will eventually find their way past the edge of the metal and it will sink, unless the metal is shaped like an inverted bowl, to prevent this. In this case it might also trap some air, unless a hole is present at the highest point. StuRat (talk) 19:55, 31 December 2014 (UTC)[reply]

Personally, I like to think of it as displacement. If the object displaces more water weight than it weighs, it floats. A rigid gallon container van hold about 8 pounds of water. So an empty container can float an 8 pound object (less the weight of the container. Ships are often listed as displacement for weight. The plimsoll line accounts for density. --DHeyward (talk) 04:26, 1 January 2015 (UTC)[reply]

Bumper cars security when obtaining power just from the floor

By these new bumper cars, where the power is draw completely from the floor, without a roof connection, how do they avoid people getting burned if they step out of the car?--Nntt21 (talk) 19:43, 31 December 2014 (UTC)[reply]

Sounds like they work by electromagnetic induction. That requires a metal coil to pick up the electricity. StuRat (talk) 19:50, 31 December 2014 (UTC)[reply]

See our article on Bumper cars - it's explained there. Richerman (talk) 20:03, 31 December 2014 (UTC)[reply]

No it isn't. The article just explains how the floor works: there are alternating strips of opposite polarity, and the car has enough contacts to pick up both polarities and some sort of automatic switching power supply to deal with not "knowing" which contacts are which. Nntt's question is, if there are strips with opposite polarity on the floor where a person could step on both of them, why isn't that a hazard? (Suppose the customer's shoes are electrically conductive, for example because it's raining or they stepped in a fountain pool or something.) --65.94.50.4 (talk) 09:26, 1 January 2015 (UTC)[reply]

It would only be a potential (ha!) problem if someone got out of the car while the ride is running, which is pretty dangerous for reasons unrelated to electricity as well. Whoever is running the ride can easily and quickly turn off the power, just like when the ride ends normally. So it's only a problem for as long as someone is out of the ride and on the floor before the carnie notices it and pushes the red button.

Is it really a serious safety problem unless there is also some other contact in addition to the shoes (like lying down across the floor)? Having "just the sole of the shoe" completing the circuit wouldn't send current through anything except the shoe.

For interest, I googled a few suppliers...looks like floor pickup systems run in the vicinity of 45 volts. DMacks (talk) 10:08, 1 January 2015 (UTC)[reply]

Influenza vaccine allergy

While administering my flu shot today, the pharmacist gave me a routine warning document (I want to call it an MSDS!) and noted that something like 1 in 1,000,000 patients will experience a serious reaction. A US government webpage makes me guess that he was referring to an allergic reaction, but the only thing in Influenza vaccine#Safety with comparable numbers is Guillain-Barré, not an allergy. What kinds of allergic reactions is the government discussing? No medical advice requested; I'm one of the 999,999 patients who didn't have a reaction. Nyttend (talk) 20:36, 31 December 2014 (UTC)[reply]

Don't concern yourself about it. What supposed reactions your paranoid pharmacist gave you doesn't matter. The UK government let it slip-out recently, that swine flue vaccine could cause narcolepsy in children. [54] But the vaccine industry earns billions and so a few unsubstantiated cases should not stand in the way 'of the greater good' (and profits) which 'you' are employed to deliver. You have a job remember – many others don't - just be thankful for that and stop asking difficult questions. --Aspro (talk) 21:28, 31 December 2014 (UTC)[reply]

Huh? I'm not concerned: as I said, I'm one of the 999,999 who didn't have a reaction. I'm just trying to understand what reactions occur in 0.0001% of the vaccinated public upon getting this vaccine. Nyttend (talk) 23:00, 31 December 2014 (UTC)[reply]

Pharmacovigilance and the Yellow Card Scheme etc are supposed to be a an alerting tool for theses things. Yet the reporting level is so low that 1 in 1,000,000 is make-believe. The don't have the statistics. So as I intermated. Don't try to think – that is dangerous to your career. Just do -and remeber -you swallowed the blue pill. You should not be asking these questions unless the red pill looks appetizing and you are willing to both suffer and enjoy reality. --Aspro (talk) 00:30, 1 January 2015 (UTC)[reply]

I think we need to be suspicious of this sort of advice from anyone using the name "Aspro"! For this who don't know, Aspro is or used to be a brand name of aspirin in Britain. At one time Bayer, the original brand of aspirin, used to advertise that their product "DOES NOT DEPRESS THE HEART". (Which is true, but neither did anyone else's brand. Eventually they were made to stop saying that.) And I remember my mother telling me in the 1970s that when she was younger and living in England, people used to say that Aspro was bad for your heart—obviously the result of these Bayer ads. So we must be careful! --65.94.50.4 (talk) 09:36, 1 January 2015 (UTC)[reply]

Serious answer please

Trolling or joking aside, does anyone have an answer here? Nyttend (talk) 02:20, 1 January 2015 (UTC)[reply]

Who above is Trolling or Joking? Read Bad Pharma. Medical science has brought about miracles, where we live in a world today, where life is no longer solitary, poor, nasty, brutish, and short. Yet , modernization, has created a world were, if any of the pharmaceutical CEO's don't satisfy their shareholders -his out. So the CEO's make sure that your heath professional (the guy that you see) is overwhelmed by pseudo – science. Ignorance may be bliss, but then again ignorance may be <fill your own words in here>. --Aspro (talk) 03:38, 1 January 2015 (UTC)[reply]

I googled "reactions to flu shot" and a bunch of entries came up, including this one:[55] Where that "1 in a million comes from" might be anybody's guess. It sounds like a suspiciously round number. ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:47, 1 January 2015 (UTC)[reply]

It should be a suspiciously round number. There's no way anyone has the data quality to give say you have a 1/706,897 risk. Nil Einne (talk) 06:35, 1 January 2015 (UTC)[reply]

In 2009-2010, 82 million doses of influenza vaccine where administered in the US. That year, the Vaccine Adverse Event Reporting System recorded 116 instances of anaphylaxis (a potentially life-threatening allergic reaction), 98 cases of Guillain-Barré Syndrome, and 48 deaths (about half from heart problems and nearly all from people with identifiable preexisting conditions) [56]. Anaphylaxis, when it occurs, is pretty immediate so there is little doubt that it is caused by an allergic reaction to vaccine components (typically the eggs used in its production). The GBS association has been studied in detail for a long time and is plausible, though the overall risk is small and the reason for the connection is not well understood. Most of the other severe adverse events are likely to be coincidental. Of course the existence of mild averse events, e.g. aches, pains, and fever, are not uncommon, but I don't think those are the kind of events you are talking about. Dragons flight (talk) 03:21, 1 January 2015 (UTC)[reply]

Prove the Square-Cube Law

I noticed that in the wikipedia entry for this law (Square-cube law), no proof of the law is given.

I would like a proof that the ratio of the areas and volumes of 2 similar figures is the square and cube of their scale factor respectively.

Thanks. 175.156.52.140 (talk) 00:06, 1 January 2015 (UTC)[reply]

I think you can just prove that visually. Let's do area here, were we can show that the area of squares 1, 2, 3, and 4 units wide are 1, 4, 9, and 16:

**
**

***
***
***

****
****
****
****

Therefore, it varies with the square of the side length. Feel free to try any other shape besides a square. For volume, that's a bit harder to show here, but you can draw some cubes and count the number of cubic units in each. StuRat (talk) 00:26, 1 January 2015 (UTC)[reply]

What sort of "proof" of the square-cube law is the OP looking for? It's like asking for a proof of addition based on multiplication. One doesn't ask for proof of the obvious based on the obscure. μηδείς (talk) 01:54, 1 January 2015 (UTC)[reply]

Your point is perfectly reasonable, but actually the OP is correct. Mathematicians do ask for (indeed demand) proofs of the (intuitively) obvious, based on the (well-established but) obscure knowledge they possess. This is certainly one of those things, as it is intuitively clear enough that every volume must be something cubed, and every 2-d thing must be something squared, but it is a mathematical fact, and this needs to be demonstrated. IBE (talk) 06:32, 1 January 2015 (UTC)[reply]

It's been a long time since elementary geometry. Is this "law" actually a law or it is a theorem? If it's actually a law, there is no proof involved - it's taken as a given. If it's a theorem, there should be a proof somewhere. ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:50, 1 January 2015 (UTC)[reply]

I do most of my higher math intuitively based on shapes, but it would seem trying to prove that the surface area of a cube increases by a factor of 16 when the length doubles and the volume increases by 8 is just obvious by definition. The math desk would be the place to ask for a proof proof. μηδείς (talk) 04:46, 1 January 2015 (UTC)[reply]

I assume you meant the surface area increases by a factor of 4? Surely a typo, IBE (talk) 06:35, 1 January 2015 (UTC)[reply]

It's straight forward, and in the article, that a surface area is a square law and the volume is cubic. The proof that it is monotonic is the derivative rate of change is linear for surface area while a square law for volume. The volume will always expand faster than the surface area. --DHeyward (talk) 04:53, 1 January 2015 (UTC)[reply]

I think they want the 3-D case of one of the three 2-D proofs in [57]. An easier way might be to build a little on [58]. But honestly, how can this possibly be anything but homework? 63.228.180.122 (talk) 06:18, 1 January 2015 (UTC)[reply]

I can't say why it couldn't be homework, but I don't see why it would be either. It's a perfectly reasonable question here, but it would be a weird one to set a student. Stranger things have happened though - my chemistry teacher had to answer an exam question, "Why do you believe in the atom?" IBE (talk) 06:32, 1 January 2015 (UTC)[reply]

So long as it's for your own interest, and so long as you know this isn't very rigorous, proceed as follows. For surface area, draw a bunch of squares of length L on the figure. Discard any leftover bits, and the area is (the number of squares) X (the area of one square). This is an approximation, because we discarded some stuff, and the "squares" aren't really square at all, if your shape is a sphere. So these "squares" are really "curvy squares". Then proceed in a sequence, with squares of size L/2, L/4, L/8 etc. Assuming the shape possesses finite curvature (ie it is not a fractal), the area of the stuff you discard will shrink to zero, and the "curvy squares" get flatter as you proceed. So it gets closer and closer to just a bunch of squares, and it approximates the true surface area. In the limit at infinity, it is exact. I call this a PGP, or "Pretty Good Proof". Proceed similarly for volumes, using cubes not squares. IBE (talk) 06:47, 1 January 2015 (UTC)[reply]

The law isn't actually correct for fractals, but then again a fractal surface would be infinite for a finite volume. Many biological structures like for instance the lungs approximate fractals to exploit this feature and scale differently within a wide range. Dmcq (talk) 12:44, 1 January 2015 (UTC)[reply]

This is a good question, and one that cannot be formally answered with elementary mathematics because the general concepts of (planar) area and of volume, simple as they are for simple geometric figures, are more complicated than they seem. The concepts are formalized by measure theory, which wasn't well developed until about one hundred years ago and is a subject which, in most universities in the United States (where a typical bachelor's degree takes four years of study), is taught to third year students in a class called Real Analysis for mathematics majors and somewhat less formally in a class called Advanced Calculus for engineering majors, and is taken only after having completed three to four semesters of regular calculus. (Physics majors often have the option of choosing between the two classes.)

Students learn in theses classes that Real numbers are stranger than they first seem, and that, just as it is possible to construct pathological functions which behave in strange ways, there are subsets of the Euclidean spaces ℝ² and ℝ³ which either don't have well defined areas or volumes, or whose areas or volumes behave unexpectedly. See Banach–Tarski paradox for an example.

The formal definition of (planar) area is touched on at Area#Formal definition and a similar definition holds for volume. Note that most of this describes the general behavior that the area (or volume) concept must obey, but that it also includes the stipulation that the area (or volume) of a rectangle (or rectangular cuboid) is what we expect; that is, a rectangle of dimensions a and b has area ab and a rectangular cuboid of dimensions a, b and c has volume abc.

Clearly the area of two similar rectangles varies by the square of their scaling factor and the volume of two similar rectangular cuboids varies by the cube of their scaling factor. Any proof that a particular subset P of ℝ³ has a given volume will use constructions which can eventually be traced back to rectangular cuboids, and so a parallel proof for the volume of a subset Q which is similar to S but scaled by a factor of s can be made using rectangular cuboids similar to those used in demonstrating the volume of S, scaled by the same factor s. Since the volume of those rectangular cuboids varies with s³, so will the volume of the subsets P and Q.

Formal treatment of surface area adds some additional complications (Surface area#Definition touches on them) but in the end the measure of surface area is related to the measure of planar area, which is itself based on the area of rectangles. And since the area of a similar rectangles varies with the square of the scaling factor, so does the surface area of similar three dimensional objects. (Where the surface area is defined, that is. It is possible to construct subsets of ℝ³ which have well defined and finite volumes but which have undefined or infinite surface area.) -- ToE 14:13, 1 January 2015 (UTC)[reply]

vegetable oil additive

how to mix epdm(ethylene propylene diene terpolymer),eva(Ethylene-vinyl acetate) and pmm(poly methyl methacrylate) additive with vegetable oil for lubrication49.15.140.116 (talk) 03:46, 1 January 2015 (UTC) 01-01-2015[reply]

Meta-Data question

If I want to know what Muscle relaxants cause appetite loss as a side-effect, where could I easily check it (Going through the articles\Pamphlets of all of them could be very long). Thanks for the helpers, Ben-Natan (talk) 06:38, 1 January 2015 (UTC)[reply]

Sounds like you need a copy of the Physicians' Desk Reference which any decent public library should have. Note, however, that it will probably abridge most side effects less important and less frequent than the more serious and common effects. You might have to search PubMed to confirm your findings. Are you looking for a muscle relaxant which does cause loss of appetite, or one which does not? 63.228.180.122 (talk) 08:22, 1 January 2015 (UTC)[reply]

Thanks for the detailing. I want to know which of them does indeed cause it. Ben-Natan (talk) 11:12, 1 January 2015 (UTC)[reply]

River landscapes

What causes the typical river landscapes you see in Europe with green either side, sometimes hills. Normally this happens on very wide rivers. 176.251.149.108 (talk) 12:34, 1 January 2015 (UTC)[reply]

I'm not sure if Cycle of erosion will help. It contains additional links that may be of assistance. Bus stop (talk) 12:56, 1 January 2015 (UTC)[reply]

Fluvial, Flood plain, Valley and River phenomenon may also be useful articles. Tevildo (talk) 13:11, 1 January 2015 (UTC)[reply]

Marlins Park

When a foul ball smacks the wall of that tank, does it cause pressure waves through the tank water that shocks the fish? 75.75.42.89 (talk) 15:02, 1 January 2015 (UTC)[reply]