Wikipedia:Reference desk/Archives/Science/2013 August 4

= August 4 =

# of days Medicare pays in rehab
My friend was told Medicare would pay only up to 20 days in rehab. Is this new? It used to be 30 days.```` — Preceding unsigned comment added by 71.232.189.242 (talk) 01:14, 4 August 2013 (UTC)


 * I believe that is true, and then it pays 80% out to 100 days. But I may be wrong.  Bubba73 You talkin' to me? 01:43, 4 August 2013 (UTC)


 * It's probably worth pointing out that there is more than one country in the world with a health scheme called Medicare. And, not surprisingly, they're not all the same. HiLo48 (talk) 02:27, 4 August 2013 (UTC)
 * Yes, but it is unlikely that someone from Massachusetts would be interested in any program from outside the U.S. -- Jayron  32  03:08, 4 August 2013 (UTC)
 * North America (USA & Canada) plus Australia, at least use 'Medicare'. (National Health Service(NHS) in England) --220  of  Borg 06:52, 4 August 2013 (UTC)
 * Missed Medicare Resources in Hong Kong. --220  of  Borg 07:23, 4 August 2013 (UTC)


 * In Canada it is only called medicare in New Brunswick. TFD (talk) 07:31, 4 August 2013 (UTC)

Bee-eater pic
In of a European bee-eater, what's that butterfly it's holding in its beak? 24.23.196.85 (talk) 05:55, 4 August 2013 (UTC)


 * Looks like Vanessa cardui. What you see are mostly the undersides of the left fore- and hind-wing. --Dr Dima (talk) 01:49, 5 August 2013 (UTC)


 * Thanks! I prob'ly should've known this -- it's one of the most common lepidopterians in the world (better known as the Painted Lady).  BTW, does anyone know whether it's toxic like the Monarch?  I've checked the article, and it says nothing about that.  (It does say in the Bee-eater article that the bird avoids certain toxic insects, but doesn't say which ones -- only that it (obviously) doesn't avoid bees, which are also quite toxic.) 24.23.196.85 (talk) 05:31, 5 August 2013 (UTC)
 * No definitive reference found either way, but in 45 years of active interest in lepidoptery, I've never seen it suggested that this or related species in Great Britain are significantly poisonous to birds. {The poster formerly known as 87.81.230.195} 212.95.237.92 (talk) 14:10, 5 August 2013 (UTC)
 * ...and the mere existence of that photo strongly suggests that these birds don't avoid them! SteveBaker (talk) 15:28, 5 August 2013 (UTC)
 * Presuming, of course, this bird isn't suicidal, stupid or visually impaired. From the frequency other species crash into my clearly dirty windows, I'd say "seems to suggest". InedibleHulk (talk) 09:36, 6 August 2013 (UTC)
 * It could also be that the Bee-Eater is immune to certain toxins found in certain butterfly species (the article says it's immune to bee and wasp venom, so it could also be immune to butterfly toxins). If so, it's not the only species to have this kind of immunity -- the Black-headed Grosbeak, for example, can even eat the highly toxic Monarch butterfly without harm to itself! 24.23.196.85 (talk) 01:23, 7 August 2013 (UTC)

posthumous fatherhood from culled sperm
Is it possibe to make a dead man father children through Testicular sperm extraction? Pass a Method  talk  12:34, 4 August 2013 (UTC)
 * That process requires live sperm, so it will be progressively less successful as the sperm die following the death of the man. The time from death until there are no viable sperm will depend on many conditions, including the condition of the testicles at the time of death. This search for direct answers was unrevealing. -- Scray (talk) 13:22, 4 August 2013 (UTC)
 * Was the sperm extracted before or after death? A dead man can have previously donated sperm the normal way, and had it properly frozen.  The thawed sperm can then be used to posthumously conceive a child.  -- Jayron  32  01:54, 5 August 2013 (UTC)
 * Would a man who froze to death and stayed that way be a candidate? InedibleHulk (talk) 09:38, 6 August 2013 (UTC)
 * I suspect it would depend on how he got that way. Generally sperm banks freeze the stuff really quickly in liquid nitrogen or something.  A very slow freezing might somehow damage the material - or freezing to the wrong temperature might be an issue.  I'm not 100% sure about that - but it's certainly a potential problem. SteveBaker (talk) 16:39, 6 August 2013 (UTC)

Is it possible to study human language development
Is it possible to study human language development by filming a human from birth to death and recording down all visual and audio signal that a human has come across in their lifetime. This capability must surely be possible with the budget of a large country like USA. The source of data will be useful for scientists for hundreds of years to come to analyse the psychological development of a human. So why was this not initiated? Surely the scientist around the world can easily obtain funding to perform the experiment. It cannot be because of privacy because the data(film) will never be released to the general public. 220.239.51.150 (talk) 15:38, 4 August 2013 (UTC)
 * Sure it's possible, it just isn't very practical (not to mention that it raises a plethora of ethical questions). Anyway, the ref desk really isn't the place to speculate on such things... 70.112.97.77 (talk) 16:18, 4 August 2013 (UTC)


 * Bear in mind that a year of film takes a year to watch. Looie496 (talk) 16:28, 4 August 2013 (UTC)
 * Almost certainly the technology exist to make it technically possible. (I even recall a science fiction story where everything and everyone was recorded 100% of the time.) But, as IP 70. says, it raises ethical questions. Would any parent consent to a child being filmed 24/7 from birth? Humans tend to find privacy pretty important Sounds a bit like The Truman Show --220  of  Borg 16:54, 4 August 2013 (UTC)


 * The technology to record that much stuff is too recent to have been used to record an entire human lifetime...so no, it can't possibly have happened. It has, however, been done for shorter periods quite recently.  For example, this excellent TED talk discusses recording all of the activity in an entire house as a child goes from birth to being able to talk.  He tracked every single time his child made a noise when water was involved and got a beautiful series of audio snippets that showed how the child went from having no speech to being able to say the word "WATER" perfectly. SteveBaker (talk) 21:45, 4 August 2013 (UTC)


 * Classic link there from Steve, but it should be noted that it's the researcher's own child, so he has a lot more leeway. Raising a child so you can keep a camera on it for its whole life, so you can use it to extract data, sounds more like the subject of a Jodi Picoult novel than a real research experiment. If you did it at a university, you would have to go through an ethics committee, and they would be likely to block it, I would assume. Privacy is absolutely an issue, because at least the researchers would need to have access to the data, and they do not enjoy unfettered access to anyone's private world. They are not the CIA, after all, nor even anything close. The child, upon reaching almost any age, would have the right to withdraw consent, and that would simply make it pointless. Also it would have to be followed through by different researchers. I would say any research like this is a long way off. IBE (talk) 13:32, 5 August 2013 (UTC)


 * How would that help much in studying language development? Every parent in the world has a good idea of what their child hears, from the moment of birth to early childhood.  That knowledge doesn't give them any insight on how the brain is structured, how sound is processed, the role of nature vs. nurture, whether a universal grammar exists, whether a critical period exists for language acquisition, etc.  A better experiment would be to deprive a child of any language and see if they can still a language after childhood.  This "forbidden experiment" has been done before, and the answer seems to be no: see Genie (feral child) and Victor of Aveyron.  --Bowlhover (talk) 08:11, 5 August 2013 (UTC)


 * I think there is something to be gained by careful observation over time - and being able to go back and note carefully how speech transitions from one phase of development to the next would be valuable. For example, my son started off saying single words - then went to beautifully, grammatically correct phrases - then seemed to take a step backwards and start saying grammatically incorrect phrases before eventually correcting those errors and becoming fluent.  The reason for this is that the first grammatically correct phrases were being memorized in one chunk - like they were a single word.  Only later did he start trying to form new phrases - and having to actually master grammar.  This tells us all sorts of interesting things - but having noticed that change, I was unable to go back and see how it started.  There is no doubt in my mind that having a record of everything the child ever said would be useful in understanding the stages of development.  But as Been Emotional said - it's an ethical nightmare to do that.  Sure, researchers would love to have all of the episodes of The Truman Show on DVD - but that's not going to happen. SteveBaker (talk) 14:17, 5 August 2013 (UTC)


 * It occurs to me that we should mention Lifelogging.
 * This is the idea that people might voluntarily record everything that happens to them (to at least some degree). Some of those people attempt to record everything they hear and see (including their own voices) - and often other data like body temperature, heart rate, blood pressure and so forth.  I suppose that if they chose to make that vast pile of recordings available towards the ends of their lives, it might tell researchers quite a bit.  The problem, again, is that this is a relatively new idea - and the technology to store all of that data and to capture it using a portable device is still non-trivial.  Certainly it's becoming possible though.  The Google Glass headset can record sound and video and stream it continually via your cellphone to some kind of "cloud" storage system.  I'm not sure the battery life of headset and phone are yet good enough to record everything on a 24/7 basis without recharging issues...and there might be times when cellphone access was patchy or unavailable - but with spare batteries and an acceptance that some data might be lost - this is becoming plausible.   Another issue is that this is something that's really only being done by adults - so it'll miss that person's childhood language development - having a child wear something like this from birth is clearly unreasonable. SteveBaker (talk) 15:26, 5 August 2013 (UTC)

Do boron exists in asteroids?
I want to make a science fiction story that is based on polywell reactors for space energy, and so because it uses aneutronic fusion its fuel is hydrogen and boron. There is a lot of hydrogen in space, from ice electrolysis, but I never find any reference to boron in space either in asteroids or other planets 140.0.229.26 (talk) 15:55, 4 August 2013 (UTC)
 * See this paper for a review of the data on boron abundance in meteorites -- the best source of evidence. The answer seems to be yes, but not in very high concentrations. Looie496 (talk) 16:25, 4 August 2013 (UTC)


 * Where does the element boron come from? A few physicists from University of Illinois have already fact-checked and veried some of the claims in our boron article.  Like those professional physicists, I (as a non-practicing physicist) have not ever heard much talk about stellar nucleosynthesis of boron.  (Compare, say, hydrogen-burning, lithium burning, nucleosynthesis production of sodium, or iron... these were all homework problems in one astronomy-related class or other, and the details stick in my mind!)  But I remember no discussions about boron!  This is apparently because boron isn't commonly made by stellar nucleosynthesis - at least not by the major reactions.  Boron is made by a more esoteric process, spallation of lithium by high-energy cosmic rays.  As such, it's going to be much more rare everywhere in the universe: on earth, in asteroids, in stars.  Nimur (talk) 17:07, 4 August 2013 (UTC)
 * Are you sure you're not thinking of Beryllium? 202.155.85.18 (talk) 01:17, 5 August 2013 (UTC)
 * I frequently think about beryllium, but in the instance above, my thoughts, discussion, and the source I linked to were related to boron. Some of that discussion also applies to beryllium - which is commonly produced by cosmic ray spallation, because (like boron) production of beryllium by stellar fusion requires a very low-probability reaction.  I found this website from the folks across the bay: "how did the various chemical elements of the periodic table form?"  Nimur (talk) 03:07, 5 August 2013 (UTC)
 * I have nothing to add here. I just really like the phrase "I frequently think about beryllium". You should get that on a T-shirt, or in Latin on your coat of arms. APL (talk) 11:27, 5 August 2013 (UTC)
 * "Soleo cogitare beryllium" - sounds pretty good! SteveBaker (talk) 20:18, 8 August 2013 (UTC)


 * I'm getting a mental picture for your story: A team of 20 mules, in spacesuits of course, hauling one of those asteroids away. ←Baseball Bugs What's up, Doc? carrots→ 22:55, 4 August 2013 (UTC)


 * Seems good enough. It seems that the story will be like a huge evil company controlling all boron mines on earth and the researchers found out about boron on space so they are trying to escape from that evil company monopoly, ohh wait seawater have a lot of boron.... Is there any way to extract boron out of seawater? 140.0.229.26 (talk) 00:42, 5 August 2013 (UTC)


 * Yes, but it seems the reason for it is to make safe drinking water, not to get the stuff. Clarityfiend (talk) 00:56, 5 August 2013 (UTC)


 * As a matter of fact, it's also possible to extract pure boric acid from seawater by means of liquid-liquid extraction with ethohexadiol (formula C3H7CH(OH)CH(C2H5)CH2OH) or similar chelating agents; however, for economic reasons this is normally done with concentrated salt-lake brines rather than seawater. 24.23.196.85 (talk) 01:31, 6 August 2013 (UTC)

Fooling Archimedes?
The other day I got into a debate with a friend concerning the Archimedes Principle. I raised the point that in some circumstances a carefully constructed object could be devised to fool the test - the interior of the object could simply be a combination of materials of different densities that balance out to the target density; for example, a hollow (ie: air filled) gold plated cube with just the right amount of lead applied to the interior walls. It makes perfect sense to me, but my friend seems to think that I'm horribly mistaken. Can someone here help settle the debate? 70.112.97.77 (talk) 16:05, 4 August 2013 (UTC)


 * Gold (19.30 g·cm−3) is denser than lead (11.34 g·cm−3). AndyTheGrump (talk) 16:09, 4 August 2013 (UTC)
 * To expand: the problem given Archimedes was to determine if a solid object was made of gold. Lead is much less dense than gold. You would need something denser than gold as well as lead to make something with the same density as gold. What you are saying would be right in other circumstances but the thief would have had to use something like osmium or platinum with the lead, which they didn't have at the time and are extremely expensive. Dmcq (talk) 16:13, 4 August 2013 (UTC)
 * Sorry, yes, I really should have consulted the periodic table before posting! Okay, so assuming that some denser material were available then it would be possible. Thanks! 70.112.97.77 (talk) 16:27, 4 August 2013 (UTC)
 * Sure, fooling the Archimedes test that way does indeed work. With some simple assumptions like the cavity is located so it does not change the object's center of mass.
 * In the particular case of fake gold bars, type tungsten gold bar or fake gold bar into your favorite web search engine. Tungsten is so slightly lighter than gold that simple tests have a hard time detecting it. For fake gold you'll need a metal that is both heavier and cheaper than gold (the periodic table leaves you little choice there), and can't easily be told apart from gold (electric conductivity, behavior in electromagnetic fields (see metal detector), doesn't give off radiation, etc). And someone will quickly figure out how to detect cavities inside a gold bar if those start appearing on the market - tap it, if it rings like a bell, well, uh oh... 88.112.41.6 (talk) 20:29, 4 August 2013 (UTC)
 * Above was mentioned center of mass... but a proper fake should also preserve the moment of inertia! Two objects with the same center of mass, but different moments of inertia, behave very differently.  Just by swinging a hollow metal sphere around a little bit, or rolling it around... we could measure a difference, even if its average density and center of mass were perfectly matched to another solid sphere of the same outer dimension.  I'd wager a gold brick that most people could even "feel" the difference, without rigorously measuring it.
 * We could enumerate other physical properties we might test: any imperfection in mimicking the correct thermal capacity or thermal conductivity won't make it past a few really "low-tech" tests. Nimur (talk) 22:30, 4 August 2013 (UTC)
 * The density of tungsten is very similar to that of gold and the bar sounds about the same, an easy way to find if a bar contains tungsten is to use a strong magnet, gold is diamagnetic, it repels a magnet, whereas tungsten is paramagnetic and so is attracted. See Dmcq (talk) 23:28, 4 August 2013 (UTC)


 * I don't think "Archimedes' Principle" is the phrase you're looking for. That describes a property of buoyancy, not the "Eureka" moment where he realized that an object displaces a volume of fluid equal to its own volume. (And then used that to calculate an objects density, thus proving it was made from gold.)
 * Perhaps that's the "horrible mistake" your friend believes you've made. I don't believe that you could construct an object that would defeat the Archimedes' Principal. APL (talk) 11:24, 5 August 2013 (UTC)
 * It wouldn't have been possible at the time of Archimedes to make something with the density of gold out of other materials but it is quite easy to do nowadays. That's what another contributor was saying above about searching for tungsten gold bar, people have been swindled using imitation gold bars. Dmcq (talk) 11:51, 5 August 2013 (UTC)


 * And of course Achemedes could have been fooled too if the object in question was hollow. His approach would say "This is not gold" - even though it might well be. SteveBaker (talk) 15:14, 5 August 2013 (UTC)
 * That wasn't Archimedes' task - he was trying to see if the king was being cheated. A hollow space would be just as damning as an admixture.  (Though I have a feeling that in such situations, the real answer is, come up with a great experiment and describe it to further your reputation, then tell the king whatever result he wants to hear!) Wnt (talk) 18:21, 5 August 2013 (UTC) oops, that was stupid, nevermind - he'd have weighed the crown and if it were all gold, that shouldn't be punished Wnt (talk) 19:45, 5 August 2013 (UTC)
 * Dmcq, yes. But my point was that constructing such an object would not defeat the "Archimedes' Principle", it would defeat the gold-test that Archimedes invented while taking a bath. They're not the same.
 * Archimedes is famous for more than one thing. APL (talk) 22:19, 5 August 2013 (UTC)

What kind of insect is this?
What kind of insect (an orthoptera, I suppose) could this be? It was found in Southern Germany, on a basil leaf. Thanks. --Edcolins (talk) 19:13, 4 August 2013 (UTC)

It must be a female speckled bush-cricket. Could somebody confirm? --Edcolins (talk) 20:01, 4 August 2013 (UTC)

Yes, speckled bush cricket, female from the ovipositor curving up at the back. Richard Avery (talk) 06:29, 5 August 2013 (UTC)
 * Thank you! --Edcolins (talk) 19:29, 5 August 2013 (UTC)