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

= May 17 =

How old do you have to be a nurse in Japan?
How old do you have to be a nurse in Japan? Neptunekh2 (talk) 01:42, 17 May 2011 (UTC)
 * You can try asking the JNA . But it wouldn't surprise me if there is no age requirement. Instead you will need the necessary qualifications and training. You will also need to be able to do the work which may impose physical requirements. Finally you need to be able to convince some to hire you (and of course need to legally be able to work at your age or obtain some sort of legal exemption). Other then age discrimination (although the law may limit the legal aspect of this ), there may also be issues surrounding potential liability/responsibility and contracts signed by you and perhaps other limit on your work which may affect the willingness of someone to hire you. In other words a child prodigy may be able to become a nurse at 15 (the minimum age for employment), but without any disrespect to the profession, I don't think it's common that child prodigies (or their parents) aim to become nurses. For most people, age isn't an issue since by the time they become a nurse they're probably older then 18,  shows only a small percentage fit into the under 25 category. Of course individual universities and training centres may have their own policies. Although interestingly there was a minimum age in the UK   Nil Einne (talk) 06:34, 17 May 2011 (UTC)
 * As a Canadian citizen, you might not have an automatic right to work in Japan. You should contact the Japanese embassy in Ottawa (or their consulate in vancouver) or visit this page of their website.  Astronaut (talk) 11:14, 17 May 2011 (UTC)


 * It isn't directly related to the original question, but I do have an interesting story related to age/job requirements. One of my friends entered college at 13 (feel free to call her a prodigy or whatever).  At the age of 17 (or maybe it was 16) she was applying for a job that she wanted to start after college.  One of the legally mandated requirements for this job was to pass a criminal background check.  Such background checks were conducted by an outside company.  After some delay, she was told that the outside company couldn't conduct a background check on anyone under the age of 18.  (I've never really understood the details of why not, but that's what they said.)  Because the background check was missing, her job application couldn't be processed.  As a result, she was de facto excluded from the job she wanted because of her age even though she could meet all of the other requirements.  Dragons flight (talk) 22:23, 17 May 2011 (UTC)

Can anyone recommend any books about Gynoid which are female robots with a human appearance.
Can anyone recommend any books about Gynoid which are female robots with a human appearance. Thanks! Neptunekh2 (talk) 01:53, 17 May 2011 (UTC)


 * One thing worth mentioning is that the robots aren't "female" or "human". Those appearances can be given to any robot, of the right general size and shape, by adding the appropriate voice, "face", etc.  (And if you're going for extra realism, you could make it get bitchy once a month.) StuRat (talk) 06:10, 17 May 2011 (UTC)


 * For some eligible works, it would constitute a spoiler for you and others to mention the roboticity of a protagonist up front, as the revelation is a significant plot point. A couple where that does not apply would be Thea von Harbou's novella Metropolis (better known in its filmed version, and primarily of historical interest), and the modern Saturn's Children by Charles Stross. Doubtless others will have further suggestions. {The poster formerly known as 87.81.230.195} 90.197.66.232 (talk) 10:12, 17 May 2011 (UTC)


 * Manga: Chobits and Yuria 100 Shiki. 93.95.251.162 (talk) 15:47, 17 May 2011 (UTC) Martin.
 * If manga counts, one of my favs is Battle angel alita. Great to hear the Cameron project is still in the works.. Vespine (talk) 01:21, 18 May 2011 (UTC)
 * Only a short story, but "Helen O'Loy" was good enough to make it into The Science Fiction Hall of Fame, Volume One, 1929–1964. Clarityfiend (talk) 05:58, 18 May 2011 (UTC)


 * Feminine Intuition by Isaac Asimov, published October 1969 in The Magazine of Fantasy and Science Fiction David Carron (talk) 09:24, 18 May 2011 (UTC)


 * Do Androids Dream of Electric Sheep? (Category:Android films should have a few other stories [most based off more than just screenplays], too)¦ Reisio (talk) 10:41, 18 May 2011 (UTC)


 * I Sing the Body Electric (Bradbury). StuRat (talk) 18:36, 18 May 2011 (UTC)

fractional volume of an extraction solvent
What is the definition for "a fractional volume of an extraction solvent"? I have attempted this homework question and given some examples as below but I mam not quite sure if I did right.

An optimum volume of an extraction solvent is the calculated volume of an extraction solvent needed to extract all the desired solute from a given mass of a solid material based on the liquid to solid ratio experimentally established.

A Fractional Volume of an extraction solvent is a fraction of the optimum volume of the extraction solvent, into which the optimum volume of an extraction solvent is equally divided.

or

A Fractional Volume of an extraction solvent is an equal fraction of the optimum volume of the extraction solvent, into which the optimum volume of an extraction solvent is divided.

If 100ml hot water is required to extract all the tea from a tea bag, then 100ml hot water is the optimum volume of the extraction solvent. Ten 10ml volumes of hot water are fractional volumes of an extraction solvent i.e. hot water. Each fractional volume of an extraction solvent can then be used to extract the tea from the tea bag in a single extraction cycle. To use all the ten fractional volumes of the extraction solvent it would need to carry out the extraction in ten extraction cycles. Should one opt to use 20ml of hot water to extract the tea from the tea bag, then the optimum volume of the extraction solvent, 100ml ought to be divided into five fractional volumes of an extraction solvent (hot water), each of which equals 20ml. The fractional volume of the extraction solvent of 20ml would then be used in each extraction cycle. —Preceding unsigned comment added by 58.240.72.212 (talk) 02:39, 17 May 2011 (UTC)

What is "Fractional Solvent Extraction"? For this question I couldn't get beyond the knowledge that this term is used in reference to Extraction using Immiscible Solvents as written by EL Comperend in 1951. However, his complicated article seems as if it has not defined the term "fractional solvent extraction" or is it that I did not get it from merely reading it. Can you please give me a definition that is ease to understand. —Preceding unsigned comment added by 58.240.72.212 (talk) 02:58, 17 May 2011 (UTC)

weaver bird nests
Hello all,

Wanted to know if weaver birds (any species) live inside their nests all round the year or only while they are rearing their young? If not where and how do they 'spend the nights'? Do they build new nests every year?

This came up while arguing that birds build nests only to lay eggs and rear young. they do not 'live' in nests in the sense we live 'in' houses, though children's books propagate this idea.

Regards Devakalpa —Preceding unsigned comment added by Devakalpa (talk • contribs) 08:07, 17 May 2011 (UTC)


 * Please see our article on bird nests. "Although nests are primarily used for breeding they may also be reused in the non-breeding season for roosting and some species build special dormitory nests or roost nests (or winter-nest) that are used only for roosting."--Shantavira|feed me 12:14, 17 May 2011 (UTC)

allosteric enzyme kinetics
I would like some help understanding allosteric enzyme kinetics, to assist me with my coursework.

A certain kinase exhibits allosteric kinetics (with associated sigmoidal plot) in the absence of UMP. When UMP is added, the plot becomes "hyperbolic", as for Michaelis-Menten kinetics.

So far, however, the material presented to me has explicitly stated that allosteric enzymes do not exhibit Michaelis-Menten kinetics. Therefore, when asked why this change in kinetics has occurred, the only explanation that I can come up with is that the UMP must be inhibiting the allosteric activator for the kinase, OR it is binding to the active site on the regulatory subunit of the kinase. Is this anywhere near correct? If so, how do I know which it is likely to be? Does the kinase still "work", and would it work as a "normal" (Michaelis-Menten enzyme) if the allosteric activator were either occupied itself or prevented from binding to the kinase? Much appreciated, 94.197.33.200 (talk) 09:52, 17 May 2011 (UTC)

Evolution of spider's web glands
Where can I read about the evolution of spider's silk glands, or does someone here know about it? Googling has onyl revealed a book review, everything else isn't particularly about evolution, just spider's silk glands in general.--92.251.154.122 (talk) 19:35, 17 May 2011 (UTC)
 * The evolution of spiders article does not discuss silk much. However, amongst its references, there are two references that discuss spider evolution, the first of which discusses silk evolution directly. CS Miller (talk) 19:45, 17 May 2011 (UTC)


 * (EC) Here is a relevant article, "A Theory on the Origin of Spiders and the Primitive Function of Spider Silk". Doesn't seem to have much on the actual glands though, just the evolutionary ecology of silk and its primitive uses. SemanticMantis (talk) 19:52, 17 May 2011 (UTC)
 * Not in detail about the glands, but something about the development of specialised structures such as gills, lungs, wings and spinnerets in different arthropods can be found in Sean B. Carroll's Endless Forms most Beautiful. --ColinFine (talk) 22:49, 20 May 2011 (UTC)

Non-organic material decomposition
Given infinite free energy and a reasonable amount of time, is it theoretically and technically possible to decompose any amount and kind of trash into separate piles of its constituting atoms, so that 100% material recycling would be possible? josei (talk) 21:22, 17 May 2011 (UTC)


 * Yes. (Some will form molecules composed of multiple atoms of the same element, but that still meets your qualifications.) StuRat (talk) 21:31, 17 May 2011 (UTC)


 * Thanks for your quick answer =). Now let's remove the Infinite thing. How much energy? say per pound of assorted trash. (I'm just trying to see if solving the problem of energy will simultaneously solve the materials problem of Earth) —Preceding unsigned comment added by Jose Icaza (talk • contribs) 22:23, 17 May 2011 (UTC)


 * Well, perhaps I should mention that, besides energy, there are other costs to consider. There's manpower, land needed for the recycling facility, etc.  And, if energy was unlimited and free, then there would be another problem, this would also make it cheaper to extract new materials from the Earth, or maybe seawater, and thus make recycling a less attractive alternative. StuRat (talk) 22:36, 17 May 2011 (UTC)


 * A bit off-topic, but I have often wondered at what point it would be economical to "mine" landfills; I have to imagine that an appreciable amount of scrap metal, and possibly other easily recycled material, goes into landfills even with modern recycling efforts. And at some point, assuming the human race survives that long, we're going to run out of easily accessible ores, and this seems like a viable alternative given how much trash we produce.
 * To slightly answer the OP, it's likely that it will be HIGHLY dependent on what elements you're trying to get out of the trash. Volatiles such as fluorine and chlorine will be strongly bonded into whatever compound it is in (the guy who invented CFCs got a Nobel Prize because the compound was so darn stable it was thought it would never break down into toxic compounds in the environment). I can't find any sources on exactly how much energy would be required, but I imagine the easiest way to reduce assorted materials to their various elemental components would be to heat the trash to an extreme degree...we're talking surface-of-the-sun hot here. In theory if you heat a molecule enough at some point all bonds are going to break. But as for how much energy this would require; your guess is as good as mine. - Running On Brains (talk) 23:43, 17 May 2011 (UTC)
 * Just to clarify: this calculation is possible, but each bond in each molecule has a different energy at which it will break. So without knowing what you need to break down the question is pretty much impossible to answer. - Running On Brains (talk) 23:47, 17 May 2011 (UTC)
 * I am bored, so I figured I'd do a sample calculation: the strongest bond that I know of (I'd be interested if someone knows a stronger one) is the triple bond between two Nitrogen molecules in molecular nitrogen. This bond has an energy of 945.33 ±0.59 kJ/mol, which means that breaking the bonds of one kilogram of N2 requires about 340 kJ of energy, or the energy needed to run a 100-watt light bulb for about 5 minutes. Doesn't seem like a lot, but remember that this is an absolute bare minimum, the actual figure needed is likely 10s or hundreds of times higher than this. Typically catalysts are used to make desired reactions more energy efficient, but these only work to aid very specific reactions, and wouldn't work for your all-purpose atom-recycler. - Running On Brains (talk) 01:58, 18 May 2011 (UTC)


 * I am thinking of a similiar idea: a universal molecule which can be programmed to reversably chelate a specific metallic target. Certain organic compounds change their shape in response to a photonic stimulus. I plan to design a molecule that is like a rubix cube, one which is solved by controlled light pulses instead of nimble hands. Sufficient complexity should allow the molecule to have a particular solution for chelating any target.


 * The whole process has to be reverable, otherwise it defeats the purpose - to extract a highly specific target out of a solid mixture. Filter the chelated target from the mixture, and recover the target. This only works for mixtures, not compounds of the target. Plasmic Physics (talk) 04:49, 18 May 2011 (UTC)


 * I remember once having a rather vivid nightmare on the topic. In the dream, I was part of a research group working on a nanotech "taproot" that would ferry up elements out of a landfill.  It was essentially made up of proteins, but with a much expanded genetic code including many of the prosthetic groups that interact with transition metals; my role involved working out a set of crosslinks (akin to cysteine, but varied) that were mutually incompatible so that folding and crosslinking could be designed more easily.  Unfortunately, the stuff managed against all expectations to eat through a glass vial and other protective equipment, and (as it was not truly biological) it had a way of converting scientists into mass for rapidly expanding tendrils, while somewhat preserving their overall anatomy in a most disturbing manner... Wnt (talk) 10:31, 18 May 2011 (UTC)


 * Wow, that apears more like a likely script for a scifi movie. It gives me some good starters for my idea. Plasmic Physics (talk) 10:40, 18 May 2011 (UTC)
 * Mass spectroscopy could be used to separate the atoms. With enough (subinfinite) time you may get proton decay or quantum tunneling into a black hole. Graeme Bartlett (talk) 12:20, 18 May 2011 (UTC)


 * There is an article about it: Plasma arc waste disposal. Ariel. (talk) 20:38, 18 May 2011 (UTC)


 * On another note, the recycling symbols on plastic do not necessarily mean they are actually recyclable, as numbers 3, 5, and 6 have low rates of recyclability. In particular, polyvinyl chloride (PVC) has a near-zero recycling rate. However, there are some bacteria that will metabolize and decompose plastics as through microbial corrosion. ~ AH1 (discuss!) 01:05, 20 May 2011 (UTC)