Wikipedia:Reference desk/Archives/Science/2009 February 6

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February 6

Is there a problem if a blood sample for indirect coombs test was taken on EDTA not serum tube?if so,what should I do if I can not reach the patient?

• • Medical Question Removed. Sorry. **

At best this is a homework question, but we don't answer those either. APL (talk) 01:21, 6 February 2009 (UTC)

Wikipedia should affiliate to a suitable group for referring if that was sensible. Coombs was the thirty year hibernating kidney monster off the x files. You should ring the doctor at least probably!! ~ R.T.G 02:05, 6 February 2009 (UTC)

Chemical vapor deposition

It's a simple idea. On Wikipedia at least, the process looks complicated, but it deals with growing nanotubes and stuff. Anyone know, specifically for amateur but serious experimentation with solar panel creation, how would I produce mini lab style deposition? Where would I find titanium oxide and/or precursors sold in quantities for mailing (in Europe)? Are precursors like that dangerous license only items? I am asking about the right material and method, right? ~ R.T.G 02:00, 6 February 2009 (UTC)

You will probably need a vacuum chamber. From my experience, this is not something suitable for amateur home-labs as it is expensive, requires lots of maintenance (not to mention technical expertise), and is potentially hazardous. Have you considered collaborating with a researcher who does CVD? It's much better to learn from trained experts anyway. Nimur (talk) 02:02, 6 February 2009 (UTC)

I don't have any experts to hand but was hoping some sort of controlled steaming or something could be done. That said, I can consider some basic engineering... Is there not a salt or something of titanium oxide? Thats the right item isn't it? ~ R.T.G 02:10, 6 February 2009 (UTC)

Right item for what? Titanium oxide is rutile or anatase you can pick that up on the ground as a rock or buy it from a rock shop - did you want to deposit titanium dioxide? 87.102.126.244 (talk) 02:34, 6 February 2009 (UTC)

Since you mention tio2 and 'controlled steaming' I'm guessing you might be thinking of Hydrothermal synthesis - is that what you wanted?? —Preceding unsigned comment added by 87.102.126.244 (talk) 02:36, 6 February 2009 (UTC)

But you mention solar panel creation - this involes a semiconductor - eg silicon - not titanium dioxide. You can easily buy silicon - but the vacuum equipment etc will/would be expensive to get. —Preceding unsigned comment added by 87.102.126.244 (talk) 02:40, 6 February 2009 (UTC)

Nanophase TiO2 is sometimes added to solar panels for its optical properties. You are right though that it is not the most significant component. Dragons flight (talk) 02:47, 6 February 2009 (UTC)

Please clarify a bit original question asker..

Either way it's not impossible to do this as a serious amateur - but if you're on a budget then I would guess the big question would be - can you weld? Vacuum pumps are gettable. You'll probably also need some sort of heat resistant, air tight electric connection to inside your machine as well (or not).

What exactly did you want to do? —Preceding unsigned comment added by 87.102.126.244 (talk) 02:56, 6 February 2009 (UTC)

Titanium dioxide (which I believe is the one you want), is extremely safe (uses include as a food additive), and can easily be purchased in bulk from chemical suppliers. In small quantities you may be able to buy it at art supply stores where is it sold as a coloring agent (white). I don't know about the feasibility of the rest. Dragons flight (talk) 02:43, 6 February 2009 (UTC)

`

I can mill, turn, fit and weld. The diagrams on depositon are for plasma nanotube generators and 15 chamber wonderlabs of intensively controlled chemical reactions (perfect like for creating a 99.999% laser wavelength-specific mirror which the things are used to make, that is beyond depositing a little by steam or ...). Cutting silicon wafers is also, out of the scope. I mean, with any hope, a bit of glass bought cheap, a bit of titanium and a little kiln. Deposition is, argueably, the most perfect field of human development out doing engineering like the hare waiting for the tortoise, it has longer legs. It is in the realm of picking up atoms and dropping them in place one by one because that is the only method to acheive more perfection than what these guys are doing with nanotubes and mirror creation. I was hoping the primitive method would be widely documented (if primitive even worked, black soot is no good for transparency, but interesting, wouldn't even a small vacuum have the largest effect on heated material?).

Dragons flight, I think you are right, anything I saw when reading up might have said T₂O or TO₂ which would be di-oxide. Although I have read a few things about the work people were doing, with reactive materials, it was nothing about identifying and using (practice) titanium or, if possible or worthwhile, playing with the titanium for effect. It was based on voltaic properties only. surely food additives and stuff are far from suitability for conductivity and transparancy? (it goes on the outside) I cannot recall titanium dioxide in food ingredients..? ~ R.T.G 13:19, 6 February 2009 (UTC)

In food, as in art, titanium dioxide is primarily a coloring agent, and according to our article it is the most widely used "white" food color. One place I distinctly recall seeing it is as an ingredient was in certain brands of Poptarts (those with white frosting). On labels it might also appear as White-171 or Titan White (presumably so you don't have to tell people that they are eating titanium). Optically it has a very high refractive index and deposited as a thin film gets used in anti-reflective coatings and other areas where its properties and low cost make it useful. Dragons flight (talk) 14:16, 6 February 2009 (UTC)

I don't think you would be able to make your own nano fabrication laboratory, which is what you seem to want to do, this is at the cutting edge of scientific research and requires UHV and clean room facilities. If you want nanotuubes, you can just buy them off the shelf, as you can get silicon wafers for use in solar cells etc. However, you could try say depositing some metal onto a silicon wafer to produce a Schottky diode, or synthesise a metal oxide semiconductor (MOS) to produce a photo diode for a solar cell and perform some current-voltage characterisation experiments or something, I presume this is the sort of thing you want to do? I think it is feasible to build a small vapour deposition chamber. You can get all the bits you need here and some guidlines for designing your own vacuum chamber are here. If you get a good vacuum system which will need a Turbomolecular pump as a minimum requirement and the chemicals you are going to deposit need to be high purity, you can get pretty much any chemical compound or element from, for example Alfa Aesar or Sigma Aldrich, although I don't know what the purchasing rules are if you are an independent researcher. Jdrewitt (talk) 15:28, 6 February 2009 (UTC)

There's some good advice there, though I doubt that the average home amateur will want (or be able) to lay out for a brand new turbomolecular pump. A quick glance at eBay shows a number of used pumps dipping into the realm of affordability (a thousand dollars and up), but most are being sold 'as-is' — which may not be a good sign for a device with high-speed moving parts. For small home high-vacuum systems, my inclination would be to nab a used diffusion pump. They're quite a bit cheaper, hardier, and they're good enough for many applications. (You may want or need to replace the diffusion pump fluid with an ultrahigh vacuum-rated fluid: Dow Corning 705 (DC-705) or a generic equivalent.) No matter what system you ultimately go with, make sure you also acquire suitable high-vacuum gauges so you have some way of knowing if your system is actually working. Extreme precision isn't that important, but you need something accurate to within at least an order of magnitude.

Perhaps more important to note, all vacuum systems present some unique potential dangers and challenges to the novice. A square foot window or panel under vacuum is supporting about a ton of atmospheric pressure. Homebuilding any sort of substantial vacuum chamber is a potentially deadly accident waiting to happen, unless you have appropriate training and supervision in that type of construction. In ultrahigh vacuum systems, you need to take great care in the selection of materials. Some types of synthetics, sealants, lubricants, and other materials will offgas for days, weeks, months, or forever under very high vacuum. A good book on ultrahigh vacuum systems would be a good investment at virtually any price. (It's no longer my field, but if someone has recommendations...?) Best of luck! TenOfAllTrades(talk) 16:09, 6 February 2009 (UTC)

I am picturing now a fluid chamber of concentrate metallic salts pumped around under pressure for a day or two on sealed back to back peices to ensure one sided coverage. It's not vacuum and wont suit the next moon buggy but still sounds like a valid method? and probably a magnituted easier than creating metallic vapor in an oven? ~ R.T.G 16:44, 6 February 2009 (UTC)

You need a way to attract the ions in your salt to the substrate, Electroplating will work and really quite simple to build an amateur system. Jdrewitt (talk) 16:58, 6 February 2009 (UTC)

Yeah but would electroplating apply to glass and be controllable enough to produce transparency? ~ R.T.G 18:18, 6 February 2009 (UTC)

Why do you want to use glass? What do you actually want to do? Its very difficult to tell. Jdrewitt (talk) 18:41, 6 February 2009 (UTC)

Make dye-sensitised solar cells. Transparent solar cells but the first ones I have seen, some time ago now, were done on peices of glass endeing as tinted glass and portrayed to be producing ample power. That or possibly other cell producing methods but they are all overly complex, aren't they? I know deposition is an expert technique but there are basic forms of everything (uniform micron depth coverage is not important for instance, any bit of a layer with good transparency and conductivity is perfect, no?) ~ R.T.G 21:07, 6 February 2009 (UTC)

Just add that "solar cell" not "transparency" is the optimal word there. Dye cells have been shown to me as highly efficient causing my interest. Also they are prescribed as easier and cheaper reproduction, with a view to producing a lot if able to produce a good example. Panels are one of the most expensive purchases even in reposession sales and little Hong Kong factories (yep). I know of dye cells for years, I don't see one for sale anywhere. Maybe other cells are surprisingly efficient also I don't know. ~ R.T.G 21:17, 6 February 2009 (UTC)

Couple of points -

• cutting silicon wafers should be easy for you - all you need is a circular disc (ie like a circular saw blade with the teeth missing) and some SiC or other abrasive grit. You could definately do that at home for 'pennies' (the process may be slow)
• TiO2 as bought would be suitable for depositing - because sublimation (the phyical-chemical process) is one of the best methods of purifying a substance known

You want to make Dye-sensitized_solar_cell right?

• The titanium nanoparticles are probably best made by a precipitation reaction. (that's my opinion) - search for "nanoparticle precipitation" + "preparation" or similar for more details if you need them. "tio2 nanoparticles" is also a good search - there may be better ways to prepare this already attached to a surface - maybe someone else will suggest a method.

The conducting top layer is Indium oxide or similar - this may be difficult to get hold of depending on what country you are in - it's readily available from lab-chem suppliers - but in the UK at least they often only deal with companies not individuals.

As for the dye - don't know . —Preceding unsigned comment added by 87.102.43.12 (talk) 21:32, 6 February 2009 (UTC)

More...

From the page Dye-sensitized_solar_cell I noticed a link to http://www.solaronix.com/technology/assembly/ - they seem to make kits - the assembly instructions might be of interest to you?

Particularily note that the TiO2 is sintered to make it stick.

With that in mind is there more specific info you need - maybe you want to try making the dye itself??? Hope the above helps (or had you already seen it). Good luck —Preceding unsigned comment added by 87.102.43.12 (talk) 21:44, 6 February 2009 (UTC)

No, sublimation I recall is part of the thing (I had some info on at one time but not now). The silicon unfortunately is of no use unless it is doped which means powdering it and adding a special compound to polarise it (one doping for positive and other for negative) I may be wrong but I have it that doped and polished silicon are more difficult to prepare and less effective (and endlessly more expensive bought prepared professionally). It fact I get a bit finger twiddly to think these new cells were outdoing for cheaper five years ago but they are expected to be popular next decade or two more. Of course nobody is tripping over themselves for solar power and stuff. Still nice to make a couple. ~ R.T.G 00:21, 7 February 2009 (UTC)

What do you mean no, you have been given some very good advice. If you had clarified your question in the first place you probably would have got it a lot sooner. Everything you need to build a dye sensitized solar cell is given here. As given above, instructions to build it are here. If you want to set up your own deposition lab, then we have given you advice how to do that. Jdrewitt (talk) 09:16, 7 February 2009 (UTC)

I meant "No, I hadn't already seen it." (not in a few years anyway.) I think I have got some very good answers so far. Any more more advice please add it, thanks Jdrewitt, Dragons flight and 87.102.43.12 especially! ~ R.T.G 12:54, 7 February 2009 (UTC)

There's not a lot more I can add - sublimation is often used to make the metal films - but in this area it's probably going to be called "vacuum deposition" or "sputtering". I'm not sure exacly what you are making - but I'd guess you will need at least one flat electrode - one fairly easy possibility (avoiding any vacuums) here is to make a silver mirror (easy using photographic chemicals, glucose and ammonia..) - If silver is no good (It can be problematic) - then you could use it as a substrate for electroplating gold, or platinum as the bottom electrode - which again is doable (Pt and Au compounds are obviously expensive but because only a layer a few (hundred) atoms thick is need you only need milligrams really).

It's the top transparent conductive electrode that seems the most difficult - here I could recommend using a half silvered mirror (with obvious 50% loss in effeciency) - though such mirrors could be sensitive to chemicals. A half silvered mirror made of gold might be better - but I don't know the chemicals to make that - there definately will be a way though..87.102.43.12 (talk) 14:08, 7 February 2009 (UTC)

That's the problem. Making a mirror will spoil the cell. It needs to provide current across the whole surface the light gets in. Double-glazing and glass-top freezers are coated on the inside to prevent misting (chemical deposition) so that seems so likely to have some method that is easy small scale. Probably far too expensive for me in any form. I wont experiment too much if I can't find some very likely to have a good effect. There are many depositions and many materials making shots in the dark likely to hit your foot. ~ R.T.G 01:00, 8 February 2009 (UTC)

Yes I agree - as I understand it any electrically conducting material will by its very nature - relect. However 1mm of silver makes a good mirror whereas 1micrometer of silver may be less effectively - even thinner layers of metal may only reflect a very small percentage of the light.

I'm not sure if there are substances which don't obey the rule I just made up above. I wonder if a minature metal mesh (like a tiny wire fence) would allow some light in, but still conduct - possible such a thing could be made by deposition with a mask, or maybe it could be made separately using etching or something. —Preceding unsigned comment added by 87.102.43.12 (talk) 14:16, 8 February 2009 (UTC)

Absolute velocity in SR vs. GR

As we are all taught, in Newton's conception of mechanics there is absolute space and absolute time. It follows that objects moving through space in time have absolute velocities in this picture.

Then Einstein came along with the theory of special relativity and nixed absolute time and space, by demonstrating that if the observed velocity of light is universal across all co-moving reference frames then the observed plane of simultaneity varies for each observer, leading to different inferred positions of observed objects. In this picture then, no object can be universally agreed upon to have any particular absolute velocity, only to have particular velocities relative to other objects.

However, by geometrising gravitation in the theory of general relativity, it seems to me that Einstein reintroduced absolute velocities for moving objects, through the back door as it were, by reifying space-time as a definite manifold. Could it not be said then that objects following inertial paths (geodesics) along the locally-flat (Lorentzian) manifold of space-time have a particular velocity with respect to that 'metric'?

In-depth responses very warmly welcome, 86.132.243.243 (talk) 02:00, 6 February 2009 (UTC)

It sounds like you are asking about inertial reference frames. Have you seen that article? Nimur (talk) 02:04, 6 February 2009 (UTC)

You are [exemplar of] the reason I qualified "responses" with "in-depth" :-) 86.132.243.243 (talk) 02:07, 6 February 2009 (UTC)

I value concise summaries : ) Nimur (talk) 16:20, 6 February 2009 (UTC)

I'm not sure I understand your concern. The Lorentzian manifold of special relativity is a specific manifold (a very flat one) and yet you acknowledge that in the framework of special relativity objects on that manifold do not have an absolute velocity. Why then do you suppose that treating objects on the more complicated manifold of general relativity as existing in a locally Lorentzian space should give them an absolute velocity? Dragons flight (talk) 02:30, 6 February 2009 (UTC)

I think what you're saying is that a general spacetime in general relativity has no (global) symmetries at all (in contrast to Minkowski spacetime and Newton's space and time), therefore you can distinguish different points, and different geodesics through the same point, by looking at the geometry. True, but no more true than for any other field, if you replace "geometry" with "configuration of the field". In Newtonian gravity you can measure the tidal force locally and use it to fix a preferred set of coordinate axes. Special relativity doesn't have gravity, but you can do the same thing with the electromagnetic field. I think any field theory makes space "absolute" in this way.

Anyway, in no sense is it true that Newtonian physics had absolute space in it and special relativity did away with that. Newton preferred to believe in absolute space even though it was experimentally undetectable according to his theory. Einstein preferred not to believe in it. It affected the way they presented their models but it had nothing to do with the models themselves. People sometimes claim that the luminiferous aether destroyed the principle of relativity in Newtonian physics, but there was never any justification for identifying the luminiferous aether with absolute space. It's a wild guess like asserting that the solar system is stationary in absolute space (something which Newton probably believed to be true). You can just as well think of the aether as a physical medium subject to the same principle of relativity as anything else. You can get a theory that's empirically equivalent to special relativity by supposing that everything in the world consists in deformations of the same medium which is the cause of electric and magnetic phenomena (sometimes called the "Lorentz ether theory"). You can get a theory of gravity this way too—not full general relativity, with its various pathologies like closed timelike curves, but enough to describe the relatively well-behaved universe that we actually observe. Physicists have by and large decided that the way to further progress is by appealing to deep symmetries like the ones behind special and general relativity. That paid off spectacularly with gauge symmetry and the Standard Model, but there's been a noticeable lack of progress since then, starting with the surprising failure of SU(5) grand unification. Maybe we've gone as far as we can with symmetry and the way to further progress is something like random dynamics. I don't mean to endorse any particular bit of fringe physics, I'm just saying that Einstein didn't do away with anything. The next level down could fit more with Newton's philosophy than Einstein's. Most physicists would say probably not, but they're just guessing. -- BenRG (talk) 15:21, 6 February 2009 (UTC)

Electrical variation on chicken and egg problem

I was given an odd homework problem today (yes, I know homework isn't allowed, but I'm not just asking for the answers...I've given this some thought). It goes as follow: In a variation of the chicken and egg problem consider this. What came first, the electric charge or the electric field? In another variation of the chicken and egg problem consider this. Mathematically we can start with the electric field and calculate the electric potential, or start with the electric potential and calculate the electric field. But physically, which comes first? Do variations in the electric field physically cause differences in the electric potential or is it the other way around? Well, for the first part, wouldn't they have come at the same time? As soon as there was charge, by the definition of the electric field an electric field would have been produced, right? Same thing for the second one I would think, because both electric potential and the electric field describe the ability of the same force to affect charges around it. Is this right? —Preceding unsigned comment added by 70.52.46.213 (talk) 02:21, 6 February 2009 (UTC)

You could read Chicken or the egg for an introduction to the "causality dilema" you are supposing.

The answer is - neither "comes first" - they are inseperable. so yes you were right.87.102.126.244 (talk) 02:31, 6 February 2009 (UTC)

Well clearly the egg came first, but I guess that's not the point lol. —Preceding unsigned comment added by 70.52.46.213 (talk) 03:03, 6 February 2009 (UTC)

At the level at which this question is probably being asked, I believe the answer intended is that they are simultaneous, so you would be right. Considered at a somewhat higher level one could argue the point in multiple ways. For example, the electric field actually propagates at the speed of light. So if you have a way to create charge, then one could argue the charge is created first and then the electric field spreads out from it. Creating charge is however hard (e.g. pair production, CP violation). Or, one can look at it in yet another way through the lens of quantum field theory and say that the electric field is simply a manifestation of the fundamental nature of space, which exists even in the absence of charge. Which is to say that an electric field (with intensity zero) existed even before there was charge, so the field came first. Such arguments, though possibly interesting for what they say about the nature of charge, are mostly an issue of semantics and of little practical use. Dragons flight (talk) 03:10, 6 February 2009 (UTC)

Robert Millikan and the Oil Drop.

The coin came up tails, so this question goes in Science, not Language.

I was reading the article on Robert Millikan. Y'all probably remember the famous Oil-drop experiment? (sure you do, since this ain't the Language Page due to the whims of chance.) So I was thinking that, since this was a great discovery, then why use the cumbersome expression "The charge of an electron is equal to 1.60218 x 10⁻¹⁹ coulombs", shouldn't the scientific community hono(u)r him by setting that charge equal to 1 millikan? However, this means that the charge of 1,000 electrons would be a kilo millikan. (you kan see where this is going). So to the question, has any SI unit been named for someone whose name starts with an SI prefix? Or have there been any close calls? Bunthorne (talk) 04:38, 6 February 2009 (UTC)

Well, electron charge = 1 is a very convenient definition, and it is indeed used extensively in atomic physics and spectroscopy. The units in which both electron (rest) mass and electron charge = 1 are called atomic units. Our article doesn't nearly do them justice, though; these are very convenient units indeed. Electron charge is very small, however; so for practical reasons the SI and cgs unit systems adopted larger unit charges, the Coulomb and the statcoulomb, respectively. Now, as far as the "kan" and the milli-kan go, there is a (very old) anecdote that one of Millikan's contemporaries suggested "kan" as a unit of conceit. However, for a typical person, even a milli-kan would be far too much :) --Dr Dima (talk) 05:42, 6 February 2009 (UTC)

Not an SI prefix, but there is the long ton, the short ton, the old ton and the new ton. --Cookatoo.ergo.ZooM (talk) 10:10, 6 February 2009 (UTC)

Megawati is on the Forbes list of the world's 100 most powerful women. Dmcq (talk) 11:34, 6 February 2009 (UTC)

Don't forget the milliHelen, which is the amount of beauty required to launch a single ship.-gadfium 11:43, 6 February 2009 (UTC)

I do not know your Millikan but this is a science question. ~ R.T.G 16:52, 6 February 2009 (UTC)

Was evolution first described by Islamic scientists much before Darwin

Dr.Jim al-Khalili of University of Surrey has contended this in several articles.How does the wiki community feel about it?(Ramanathan) —Preceding unsigned comment added by 212.247.70.129 (talk) 07:41, 6 February 2009 (UTC)

It's not a new idea, and it's actually very well established: Early_Islamic_philosophy#Evolution and History of evolutionary thought. He wasn't even the first to come up with Natural selection, which is what he actually contributed to biology (evolution was already well evidenced in the geological record, if not accepted). See Natural_selection#Pre-Darwinian_theories. Darwin is the first person to compile vast amounts of evidence to clarify and support the idea. Someguy1221 (talk) 07:48, 6 February 2009 (UTC)

He also moved it into an explicitly biological context. There's a difference between an Ancient philosopher gesturing philosophically (and probably with some moral implication) to an idea, and someone in a more modern time say, "look, here's something you can see and test and really look at the dynamics off, if we choose to study it."

I haven't read these particular Ancients but it smacks of giving Democritus credit for atomic theory—yes, he had an idea that was similar, but no, his idea looks actually nothing like modern atomic theories whatsoever. It's amusing that Draper is the main historical source cited in that Islamic philosophy article—he is not considered at all a reliable source by modern scholars (he is actually taught in school as one of the key examples of what the history of science was like before we started doing it the right way). In general most historians are very suspicious of these "me too" sorts of arguments—they often gloss over crucial differences, and are often put in the service of non-historical enterprises (national/religious pride, etc.).

For example, Al-Jahiz in that passage is getting credit for a precursor to natural selection, rather than Lamarckianism, which is clearly what he is espousing in that passage (somatic change passed on to offspring). The Brethren of Purity reads far more like Vestiges of the Natural History of Creation than it does anything Darwin would endorse. Al-Khazini's cyclical view would have been seen by Darwin as not even intended to be scientific. I'm not ragging on the Medieval Islamic scholars but the idea that their ideas have anything to do with Darwin is something that Darwin himself would have found ludicrous. He was, as noted, not just postulating transmutationism—theories of that matter were in abound even in his day and he thought most of them were sloppy and obviously wrong—but a very specific mechanism for transmutation of species. I see nothing even remotely close to Darwinism in the passages quoted; I see either Lamarkianism or vague cosmic evolution a-la Robert Chambers, but that's it. Both of these approaches Darwin explicitly put himself in contrast with. --98.217.14.211 (talk) 14:06, 6 February 2009 (UTC)

I think we need to be clear here that the OP didn't mention Darwinism or natural selection. IMHO you're confusing the different ideas. Lamarckinism is a form of evolution as both our articles say. There's no question that many scholars had evolutionary ideas long before Darwin, both Islamic and others. Most of them were mostly wrong and/or didn't know lots of things. Darwin's work may have been the most revolutinary and they were fairly close to the truth although he still got a few things wrong and there were many things of course he didn't know. Speaking of al-Jahiz, you appear to have misunderstood what the articles are saying. As far as I can tell, they are completely accurate speakin mostly of his ideas being natural selection. It's true his theories had many similiarities to Lamarckism and were therefore significantly wrong but it also involved natural selection. It was not evolution of species due to natural selection of organism with different inherited characteristics due to random changes as was Darwinism or the modern evolutionary synthesis but it was very close to natural selection nevertheless. Lamarckinism's ideas weren't explicit about the competitive advantage/natural selection bit AFAIK. They were more about inherited characteristics of organisms change because of what the environment requires of them and didn't discuss or think about whether certain organisms would therefore end up better off as a result of this and those were more likely to survive. Nowadays given what we know, it seems so natural that this is correct and this is what something means but when you think about it, it can mean something else. For example our article says "Natural selection is the process by which favorable heritable traits become more common in successive generations of a population of reproducing organisms, and unfavorable heritable traits become less common, due to differential reproduction of genotypes." Note there's nothing about the traits needing to change randomly. I for one think overemphasis on the importance of single figures often misses the point it's usually a stepwise process. As I've already said, I'm not denying Darwin's work may have been revolutionary i.e. a very big step simply that it's equally silly to ignore that it's likely the work of others contributed a fair amount to his work and ideas (i.e. quite a few small steps). P.S. I'm tired so apologise if my reply is confusing but I htink it's mostly correct though. P.P.S. Personally I doubt Darwin would be as critical as you. He would say they were wrong, but he would acknowledge parts of what they were saying were right, as I believe he said for Lamarckinism and indeed that he was influencedin some wayt by some of them Nil Einne (talk) 12:11, 7 February 2009 (UTC)

The quote in the article from Al-Jahiz seems impossible to distinguish between Lamarckianism to me... "Environmental factors influence organisms to develop new characteristics to ensure survival, thus transforming into new species." Sorry, I just don't see that as an explicit advocation of natural selection, but again, I don't claim to know Al-Jahiz in any detail. The quote is ambiguous about whether the heredity is somatic or not. Darwin's work, while it has some aspects of inheritance of somatic traits, is much more insistent on aspects of what we would today call genetic traits. The description of Al-Jahiz's work makes it sound like this is a throw-away anecdote about animals in a larger, unsystematic survey. (Which is fine—I'm sure it was doing important work in its own day!! But let's not compare it to, say, the Origin of Species, which is a very different type of document.)

Darwin would certainly be as critical about the mechanism. He devotes quite a bit of time talking about Lamarck, Chambers, and other such "vague" theories of evolution which preceded him. He of course was influenced by things, but he took explicit efforts to delineate what he thought was his unique contribution.

I'm not trying to emphasize that Darwin was a drastic break from the past, but the articles in question don't show me anything that looks like Darwin's systematic approach to the issue. This is actually what one would expect—ideas do not just pop out of nowhere, they need specific contexts to generate and to even become worthwhile questions. That the question of "what is the mechanism for the transmutation of species?" was a major question for a number of people in the late-19th century but not, say, in the 10th century, is somewhat what I would expect. It's no coincidence that the main expositors of the idea in the late-19th century (e.g. Darwin, Wallace, Huxley) had some very similar elements to their intellectual development (world travel, careful addiction to the cataloging aspects of British natural history, etc.).

Obviously looking for unisolated geniuses is not the name of the game here, and I wouldn't argue such a thing. But looking for a few vague lines in a very old work that was on a totally different topic and interpreting them as being equivalent to a 19th-century or 20-century elaborated research program is a very poor approach to the history of science. It makes as much mockery of the 10th century as it does the 19th. --98.217.14.211 (talk) 13:54, 11 February 2009 (UTC)

Voice-to-computer device

Is there a device that could translate human speech into text on a computer ? If yes, what is it called and where can I get one ? Have a nice day, Rosenknospe (talk) 11:04, 6 February 2009 (UTC)

Look at Speech recognition and maybe do a google search for 'digital dictation'. Not sure of which software packages are good but hopefully someone will come along and help. 194.221.133.226 (talk) 11:09, 6 February 2009 (UTC)

My computer of three years ago came with standard Windows XP which had a speech to text recognition package included (which I did not discover for many months!). So have a good look inside your machine before you look outside. apologies if you have done that already. Richard Avery (talk) 15:07, 6 February 2009 (UTC)

None of them are very good. That is, they can recognize a small, fixed set of words OK, but if you expect to be able to dictate any word in the English language to one and have it get it correct every time, you're going to be disappointed. They often require a training session, where you must say words from a list so it can learn your voice. Also, you must pronounce words very carefully, with extra long pauses in between, and be prepared to spend a great deal of time making corrections. StuRat (talk) 15:13, 6 February 2009 (UTC)

With adequate training, they can be pretty good. The last time I tried one was about 10 years ago and it took a lot of training, but once that was done it was pretty good. You had to speak a little slower than usual but not much, but you have to when dictating to a human too. There were a few corrections required, but not many. I'm sure the technology has improved significantly over the last decade, so it should be very usable now. --Tango (talk) 15:53, 6 February 2009 (UTC)

I disagree with StuRat's assertion that there are no good voice-dictation tools. I think his statement reflects the user-interface preference (which I also share) that keying is faster than speaking. However, that personal preference doesn't mean that voice-dictation tools are ineffective; and a realistic user survey of incorrect keystrokes vs. incorrect voice-command inputs probably puts them at around equal error rate in a modern implementation with an average typist.

IBM ViaVoice was pretty astonishing back in the day. It was well integrated into several word-processors, and also had a neat user-interface to control a lot of Windows operating-system features, in addition to text dictation. It worked in crowded and noisy environments and was fairly resilient to incorrect dictations because it used both speech phoneme and natural language statistical processing to verify the syntax of whatever it wrote down. I've also seen text dictation tools for the physically impaired (for example, a quadriplegic patient who could not use arms or hands to control a computer - I was amazed at how rapidly he could navigate the web, play card-games, and write emails, all through voice-dictation). I unfortunately don't know the name of the package he used for computer assistance, except that it was an "after-market" tool he installed on top of Windows built-in user accessibility features.

Just as a minor aside-rant - programmers and designers! Take note! Don't use wacky non-standard GUI interfaces which break compatibility with these sorts of alternative interface paradigms! Operating system widget-kits go to great pains to generate standardized toolkits, but if every designer engineers a "better" custom version, it will be impossible to interface via alternative input methods and will render your software unusable by the handicapped. Nimur (talk) 16:33, 6 February 2009 (UTC)

Voice recognition has gotten a lot of research attention in the past few years as companies try to find better ways of integrating technology into our lives. I have found that the voice recognition when I call google's free 411 service Goog411 is quite good without any training. Maybe that is just because I'm from the midwest where we have the "standard" accent [1]. Anythingapplied (talk) 18:01, 6 February 2009 (UTC)

One thing to remember with that sort of thing is they have a much lower input possibility then dictation. Nil Einne (talk) 12:28, 7 February 2009 (UTC)

The quality of recognition seems to depend on the style of speaking: if you're giving single-word commands, the software almost never makes mistakes; if you're dictating to the computer, the quality is good; if you're speaking in a conversational fashion, it's impressively bad. --Carnildo (talk) 23:29, 6 February 2009 (UTC)

Have never really used speech recognition myself but several things I believe. 1) As people have mentioned training is very important. Note also that all tools continually learn even after training so the longer you use it, the better it's likely to be. 2) Mic quality, location and the sound environment is also important. In particulr I believe echo is a big problem for speech recognition which was one of the reasons for the spectacular failure of Vista's voice recognition problem. (I looked into it at the time and many no MS experts in the field seemed to agree demoing in a auditorium is always a dumb idea) 3) Accent also likely matters. Most tools have probably had a lot more work with standard US accents then Jamaican for example. I doubt training will completely make up for this. P.S. As people have mentioned recognition for commands is a lot better then for dictation (remember the lower input possibility). Dictating in a clear, slowish, consistent style is better then conversational and if you're regularly changing your speech Nil Einne (talk) 12:28, 7 February 2009 (UTC)

Right. Well, my problem is that I'm a non-native English speaker trying to teach myself spoken English by listening to all sorts of media and it sometimes happen that I listen to something several times and *still* don't understand what the guy says. This is annoying (especially when the guy's name is Pierce Brosnan - I mean, a girl wants to know what this guy says, right ?). So I thought I'd search for a way to get the speech written on screen to better learn how words are pronounced. I actually have that Vista thingy on my home computer (just discovered it yesterday after reading your answers above, MS doesn't advertise it) and I stumbled upon the Digital dictation software article. Looks like the universal translator is still a far shot. Anyway, thank you for your answers, they are really interesting and enlightening. You guys rock ! Have a nice day, Rosenknospe (talk) 16:08, 7 February 2009 (UTC)

If you're watching movies, have you seen closed captioning? When enabled, this technology can automatically print the dialog on the screen for you to read. This is pretty standard on DVDs and television now, and it's even becoming common on internet video. Nimur (talk) 10:41, 8 February 2009 (UTC)

Closed captioning is certainly nice where it exists, but it's not universal. Anyway, I'll explore all those ideas you gave me and see if I can make anything out of them. Otherwise I'll get back to using those good old human ears and training ;D Thank you for all your help everyone ! Have a nice day, Rosenknospe (talk) 13:27, 9 February 2009 (UTC)

Feed the lions

Resolved

If you had a lion enclosure and instead of putting meat in it, you kept it stocked with fresh fruit, how long before the lions start to die of starvation? ~ R.T.G 15:07, 6 February 2009 (UTC)

Are you including them eating each other ? StuRat (talk) 15:17, 6 February 2009 (UTC)

Anything at all just fresh fruit. You think they would eat each other? ~ R.T.G 16:09, 6 February 2009 (UTC)

Humans would. So why not lesser life forms? After all, they're made of meat. Dismas|^(talk) 18:45, 6 February 2009 (UTC)

Humans would be able to do quite well living off the full stock of fresh fruit. I'm not so sure they'd have to resort to eating each other. Anythingapplied (talk) 21:21, 6 February 2009 (UTC)

Following EC: Lions are carnivores. They lack the teeth and digestive system to process and gain sufficient nutrition from a vegetarian diet. Lions do kill and sometimes eat other lions. Male lions gaining dominance over a pride will sometimes kill and eat cubs sired by their predecessor. Female lions may stay away from the pride and hide for a while to prevent that. Researchers believe the behavior is triggered by pheromones. It was once believed to be standard behavior, but recent observations of "peaceful takeovers" and prides lead by two males have called this view into question. Lionesses without a pride may get killed by an established pride. [2] Nevertheless it is extremely rare for lions to exhibit cannibalistic behavior. Fruit do not meet the dietary requirement of a lion. It may lick the juice off. A lion needs the equivalent of about 11 lb to 15 lb of meat (and bones) a day. Lions are able to survive for quite a while after gorging themselves on a big meal. They can eat up to 10% of their body mass in one sitting and then not eat again for about 4 days without trouble. With an extended period of starvation they will eventually become too weak to hunt and then lose interest in food, even when it is presented to them. Unlike smaller cats, they can't survive on insects and worms for any length of time. Lions are unable to metabolize (some) fatty acids in vegetable oils directly. Thiamine deficiency is well documented in lions (and cats) fed an inadequate diet. They lack the ability to metabolize it from food and instead rely on eating herbivores who can do so. I assume though that your lions would starve long before that takes effect, from lack of food. I couldn't find anything on fruit sugar and sugar metabolism in a hurry, but the digestive system of lions is set up to gain energy from proteins and fats. Fruit do not contain sufficient amounts of protein [3] vs. [4] even for humans. In humans 200g of protein is said to yield 200 kcal, compared to 300g of carbohydrates yielding 72 kcal. It is rather doubtful that a lion could make use of even a fraction of that. Anyone unable or unwilling to provide lions with an adequate diet should not be permitted to keep them in an enclosure! --76.97.245.5 (talk) 22:06, 6 February 2009 (UTC)

What if you put a lion, fresh fruit and a bear in all at once? TungstenCarbide (talk) 22:21, 6 February 2009 (UTC)

See bear and pick one. And how big is the enclosure? Are there shrubs or structures for the lion to hide behind? Probably: Bear eats fruit. (Lion is hopefully still full from its last meal.) Lion gets more active as time goes by and carefully approaches bear. Bear feels threatened and chases lion around. If the lion doesn't wear out too fast and gets injured by the bear, they may settle down again until the lion gets hungry enough to throw caution to the wind and stalk the bear. From then on it depends on what bear and a lot of other factors who wins. I hope no one's ever going to try and find out. Go play a video game instead. 76.97.245.5 (talk) 01:33, 7 February 2009 (UTC)

Ha Ha Although some grizzlies have lion sized strength, I don't think they would get along chasing any lions except very small cubs. Apparently the lions will eat the fruit when they get hungry enough. ~ R.T.G 12:45, 7 February 2009 (UTC)

Well, panthera leo and grizzlies don't usually meet. But mad Grizzly moms have been known to maul a full grown mountain lions [5]. So it's not a given who'll win. There's a saying about Grizzlies: Grizzlies attack when in doubt. They are also short sighted and not that bright. So they are often in doubt. (This is not very scientific, but used to caution people not to underestimate the danger.) A lion is not going to go on a full out attack when encountering something new. They'll rather approach cautiously and maybe try a mock attack to check it out. A Grizzly will think it or its food supply is threatened and will chase the intruder away. A Lion would not stand its ground against an unknown opponent unless it was defending a cub [6]. It would rather retreat to some safety to assess the situation. Lions are not built for endurance, but rather for short bursts of speed. Bears can go at a surprising clip for quite a while. If the enclosure doesn't offer any good hiding spots for the lion to approach the bear unseen it may delay its attack till it is no longer in top shape. They also usually hunt large animals in packs, so a sole lion is a bit at a disadvantage that way. If the lion doesn't get a good grip on its first attempt the bear may get a swipe in and injure the lion. Lions don't manage to get all the prey they attempt to kill. They occasionally get kicked to death by gnus they had tried to put on their menu. As i said, the outcome would depend on lots of factors. Lions don't have the teeth to "eat" fruit. They'd lick the fruit to pulp and then lick that up. Lisa4edit (talk) 10:23, 8 February 2009 (UTC)

In wow of this great answer. Best reference answer I have read? ~ R.T.G 18:18, 10 February 2009 (UTC)

Oldest ice ?

What's the oldest chunk of (water) ice on Earth ? I would guess it would be in Antarctica or possibly Greenland in a volcanic caldera or meteor crater, where the ice has no way to flow to the sea, calve, and melt. Do we have ice cores of this ice ? The European Project for Ice Coring in Antarctica article mentions a 740,000 year old sample, but do we know if this is the oldest one ? StuRat (talk) 15:28, 6 February 2009 (UTC)

People argue that some of the ice in Antarctica's Dry Valleys may be as much as 8 million years old. But the abundance of that is tiny and heavily laced with dirt (more a permafrost than an ice, really). Others think this younger, perhaps 3 million. By the nature of the Dry Valleys, those chunks are isolated and discontinuous, so they aren't useful for creating long-term records the way ice cores are. Usable ice from coring goes back about 800k in the existing samples, and people looking for better locations think 1.5M may be achievable. Dragons flight (talk) 15:39, 6 February 2009 (UTC)

Just to add to that, a combination of ice core and tree trunk information make us a rough weather pattern for those 7-800,000 pre-history years. Is that pattern on Wikipedia? (I looked for it before probably searched the wrong one) ~ R.T.G 16:50, 6 February 2009 (UTC)

See ice age, dendrochronology and Milankovitch cycles. SpinningSpark 13:29, 7 February 2009 (UTC)

The ice may have no way of melting right now, but that doesn't mean it won't melt in the near future. Global warming may innitiate melting of some of these areas. However I can't see why ice in some areas such as near the bottom of East Antarctica couldn't be several million years old. ~AH1^(TCU) 15:12, 7 February 2009 (UTC)

Innitiate = To start something in a motel room ? :-) StuRat (talk) 20:06, 8 February 2009 (UTC)

Thank you SpininingSpark ~ R.T.G 00:36, 8 February 2009 (UTC)

Euthanizing turtles

I was listening to a conversation the other day between a vet and another person. They were talking about cruelty to animals or some such thing and mentioned euthanizing turtles. Since I wasn't part of the conversation, I didn't want to interrupt. So, I'm bringing my question to you fine people! How does one euthanize a turtle? I'm familiar with the practice of euthanizing dogs and cats since I've had them as pets all my life but I'm curious if it's the same for turtles and pretty much every other animal that a common (i.e. non-farm/large animal) vet would see. Thanks, Dismas|^(talk) 17:42, 6 February 2009 (UTC)

According to the article Animal euthanasia, there are many ways of putting down an animal. According to here, large animals are usually shot, while turtles are probably gassed or killed by cervical dislocation. Queenie ^Talk 18:53, 6 February 2009 (UTC)

(e/c)It's done the same way (by barbiturate overdose). But a few questionable methods have been used in the past such as freezing and decapitation (reptiles survive decapitation for a comparatively long time). Here's an article: [7]. Fribbler (talk) 18:55, 6 February 2009 (UTC)

Though it does seem kinda appropriate that a turtle would take up to an hour to die from having its head cut off... --Kurt Shaped Box (talk) 19:46, 6 February 2009 (UTC)

wikt:appropriate ~ R.T.G 00:35, 8 February 2009 (UTC)

Corn for sugar? Why not apples?

In america it is quite common to have our main source of sugar be from corn syrup (the article is too short and not helpful). Why do they use corn? I've always thought FRUIT has more sugar than vegitables. Why not use a cheap fruit like apples? Wouldn't there be more sugar there? Thanks. Anythingapplied (talk) 17:52, 6 February 2009 (UTC)

In sweetened Soya milk apple is used rather than sugar. I think a good test of the sugar content could be to taste two equally sized peices. Corn is quite sweet for a vegetable and apple can be very bitter. ~ R.T.G 18:13, 6 February 2009 (UTC)

There is a form of sugar called fructose which is available in the UK as a sweetener, but IIRC it's not ideal because it tastes odd. This is fruit sugar. I suspect the answer to the question has more to do with the amount of sugar you can get per plant: apples are less intensive than maize. --TammyMoet (talk) 19:45, 6 February 2009 (UTC)

Perversely, while the corn syrup article that the original poster pointed to is indeed rather sparse, there's a rather more detailed one on High-fructose corn syrup, which is the substance used to sweeten many drinks in the USA. Coca Cola, for example, tastes noticeably different depending on what country you bought it in; because the local bottlers use whatever sugar source is most easily and cheaply available. This may be beet sugar, cane sugar, or, in the case of a nation that produces a lot of maize, the previously mentioned high-fructose corn syrup. Apples are indeed sweeter than corn, but you get rather fewer for a given acre of land. ~ mazca ^t|c 21:05, 6 February 2009 (UTC)

Interesting point, while never having tried it myself, I had understood that coca-cola with HFCS probably tastes different from it with sugar (as it has a rather different composition) but didn't really expect beet sugar vs cane sugar to taste different since when it's highly refined/white, the difference is likely to be rather minisicule. However I came across this [8] which suggests it may not be the case. While unfortunately most of the tests were with brown sugar, they did test with white once which suggests a difference. I say suggests, because 1) A single test is never great science 2) There was no repitition and they only used one brand, it's possible natural variation between batches or some aspect of the brands processing rather then the sugar per se makes the difference 3) It was only single blind, test people doing the test and the people doing the baking were aware (I presume) of the difference. Also I should mention that while apples are definitely a poor choice I think it's questionable if corn is really an efficient way to make a natural sweetener or whether it's solely because of subsidies in the US which make HFCS cheap. Nil Einne (talk) 10:22, 7 February 2009 (UTC)

Many "no sugar added" products contain apple juice. Apart from farm subsidies mentioned in the HFCS article, there are several factors inhibiting switching to apples. Apple trees take a couple of years before they bear fruit. Apple orchards are still very labor intensive [9], although mechanical thinners and harvesters are becoming more common. If all consumers were to decide to want fruit sugar from apples instead of high fructose corn syrup you'd get a severe crisis. It's not difficult to switch from one grain to another or even from corn to peas. You can still use most of your equipment and infrastructure. If you'd like to change your farm into an orchard you'd basically have to start over. Suppliers would have had to grow saplings for grafting years ago. Researchers would have had to develop suitable varieties for the Great Plains and the Corn belt and study soil preparation, fertilizing and erosion control there. Fertilizer manufacturers would have to reformulate their production for the new plantings. Manufacturers of farm equipment would have to revamp their factories to supply different machinery and very little of the existing farm machinery could be used in an orchard. (You might even have to get smaller trucks because they will have to fit between the rows.) Waste products would be cuttings from branches, fall foliage and unripe apples instead of silage, straw and husks. You'd have to find new buyers; or your old buyers would have to switch their business, too. Factories for producing HFCS would have to be converted to apple processing plants. Grain storage facilities converted to apple warehouses. Corn can be used to feed life-stock and poultry. AFAIK apples could only be used to feed pigs. Workloads are highly seasonal. Accommodations and facilities for a large population of migrant workers would have to be established. Lots of start-ups would be likely to fail unless the government ordered people to go work in the new orchards, because most people are not that mobile. If you used to be a qualified bank manager, earning $10.50/hr. for a couple of months out of the year just takes a long time getting used to. Cost wise I also have my doubts. Using rough and rounded numbers and ideal conditions for extraction of sugar you might get: 10 % sugars per apple from 800 lbs per bin = 80lbs of sugars per bin. Production cost of $200/bin gives $2.50/ lb and 30 bins per acre would give a yield of 24000lb of apples or 2400 lb/acre of sugars. HFCS runs around $0.30/lb bulk price [10]. So even if you sold apple sugars at cost you'd not be able to turn a profit unless HFCS became 10 times more expensive. 76.97.245.5 (talk) 00:36, 7 February 2009 (UTC)

One word to answer the OP's question about why corn is used for sweetener in the U.S. Well, 3 words: Archer Daniels Midland. It opperates in the corn market much as DeBeers does in the diamond market, and it uses its huge market share to agitate for all sorts of corn-based applications. We use corn-based sweeteners in the U.S. not because they are the cheapest or the best or any other reason execept that ADM is a powerful corporation, and using more corn makes them more money. --Jayron32.talk.contribs 05:21, 7 February 2009 (UTC)

Perhaps, but corn is certainly more cost-effective than apples for making sugar. I don't actually know what could compete with it in the US as a whole. Sugar cane might, but only the Deep South and Hawaii are suitable for growing it. --Trovatore (talk) 05:33, 7 February 2009 (UTC)

Why not sugar beet? DuncanHill (talk) 05:38, 7 February 2009 (UTC)

Also requires warmer weather than is available in most of the US.Hmm, looks like I was misinformed on this one. According to our article it grows in England, so it should hardly object to Kansas. Also it grows underground, which increases harvesting costs (really, if you don't mind digging things up, why not potatoes? all you need is starch; the enzymes do the rest).

I'm no particular fan of Archer Daniels Midland, but I don't see a conspiracy here. I haven't run the numbers myself, but I find it not at all difficult to believe that corn is the most cost-effective way of making sugar in the US. --Trovatore (talk) 05:43, 7 February 2009 (UTC)

Assuming of course that you require that the sweetener is actually made in the U.S. There's enough cane coming out of Brazil to keep us knee deep in the stuff at a very low cost, but protective tariffs make sure it's not cheaper than corn-based sweeteners. --Jayron32.talk.contribs 05:48, 7 February 2009 (UTC)

I question that. It's difficult to answer since there are few countries with comparable climates without subiidies (Europe is sugar beet land, but they also have subsidies) but IMHO the fact that the subsidies etc are greater for corn then they are for sugar beet (or cane) combined with the fact that sugar from sugar beet (and to a lesser extent cane) used to be the preferred sweetener of choice (I recognise the fact it could be due to the fact the processing required is a rather recent development) means it's questionable. Of course as others have pointed out in any case, cane sugar from other countries is probably a better choice but still I think it's always difficult to say whether even corn is the best for the US when the situation is a wacked up as it is in the US (or Europe). I don't know if I'll say it's a big conspiracy tho. That implies people are conspiring to achieve an outcome which I doubt it. Rather the power of corn growers in the US combined with the protectionism which is common worldwide particularly for agriculture have lead to a situation where certain products are favoured over others with each person having different desires and goals and few with any intention to achieve the current outcome Nil Einne (talk) 10:22, 7 February 2009 (UTC)

I could be wrong, but I believe your answer is confusing. As far as I'm aware, HFCS is really the cheapest natural sweetener in the US. Now the reason may very well be because of ADM's power but that power is used for subsidies, tariffs and the like. It's not that manufacturers have switched to HFCS because of pressure from ADM (which your answer seemed to suggest), rather it's simply that it is the cheapest product. The situation with De Beers is somewhat different, they simply control the diamond supply worldwide through a variety of legal and illegal means. Nil Einne (talk) 10:22, 7 February 2009 (UTC)

The sweetener is the cheapest in the U.S. because ADM pays lots of money to Congress (excuse me, makes, campaign contributions) and has a strong lobby which keeps it that way. Of course ADM does not force companies to buy HFCS; but what it does it work very hard at keeping HFCS lower priced than other sweeteners. If a free market were allowed, then HFCS may or may not necessarily be cheaper. We may never know, because such a free market has not been attempted. --Jayron32.talk.contribs 05:37, 8 February 2009 (UTC)

Which is what I said, the situation is rather different from De Beers however as I pointed out and your claim "U.S. not because they are the cheapest" is confusing/misleading because they are. The fact that they are the cheapest because of subsidies, and tariffs and the like doesn't change the fact that they are the cheapest. As I stated above, your answer seemed to suggest that manufacturers were choosing HFCS even though it wasn't the cheapest, which is simply not true. Nil Einne (talk) 11:54, 8 February 2009 (UTC)

Rock salt on the ice

Is it bad? Does it wither the plant life or anything? I haven't heard anything thing bad about it but maybe it melts cats or something :)~ R.T.G 18:09, 6 February 2009 (UTC)

Yes, it can hurt plants. See Salting the earth and Soil salinity. --Allen (talk) 18:20, 6 February 2009 (UTC)

Most of the road salt washes down the drain sewers into lakes and eventually oceans, so doesn't do much harm. Some plants at the edges of roads and sidewalks can suffer, though. StuRat (talk) 19:49, 6 February 2009 (UTC)

(after edit conflict) It damages cars too (in the long term) by promoting oxidation of any exposed metal (esp. underneath). --Kurt Shaped Box (talk) 19:51, 6 February 2009 (UTC)

It damages cars in the short term if a lot of it is used and you don't wash your car afterwards. --Tango (talk) 20:34, 6 February 2009 (UTC)

Agreed, but modern cars are designed to resist the corrosion caused by salt. My car is covered in salt just now, but I will wait for the rain to wash it off! Dbfirs 21:02, 6 February 2009 (UTC)

The rain does not wash your car! It rots under the wheel arches. Muck sticks to it becoming the site of ROT and bang, a car with decades of life left has loose wheels and chewed up underframe. ~ R.T.G 21:23, 6 February 2009 (UTC)

@Stu-Rat - No, no, no! Salt on the roads does not simply wash into sewers and into the ocean; it causes a great deal of harm. The salt seeps into groundwater, potentially ruining aquifers and other potable ground water sources. Runoff into lakes and rivers is no better; they're not supposed to be salty; the plants and animals living there are harmed by the brackish water. Don't use more salt than needed! Below about -10C it doesn't work anyway. Matt Deres (talk) 00:49, 10 February 2009 (UTC)

An extra question! The news reported yesterday that some councils here in England are running out of rock salt. The item said that they couldn't have huge stock piles as it goes off and "is completely useless for the roads". How does it "go off"? --TrogWoolley (talk) 21:46, 6 February 2009 (UTC)

My guess would be that it absorbs moisture. Just like the salt in your kitchen cupboard goes all clumpy and useless over time (although it probably has anti-caking agents added to prevent that, perhaps those don't work for road salt somehow?). --Tango (talk) 22:03, 6 February 2009 (UTC)

That would be my guess too. Once it gets water in it, it turns into a big solid lump that's no good for anything. --Kurt Shaped Box (talk) 23:34, 6 February 2009 (UTC)

As to the anti-caking agents, presumably these raise the cost and they might also work only with finely granulated salt. Road authorities deal with huge quantities of salt and normally get by fine without anti-caking it, and they don't need the stuff finely ground. --Anonymous, 03:47 UTC, February 7, 2009.

I'd think a road crew could invest in a device to grind the salt back up into a usable size. After all, they must have such a device that was used when they pulled the huge chunks of salt out of the mine. StuRat (talk) 09:18, 7 February 2009 (UTC)

The miners will have such a device, that's a long way up the line from the road crew... It may not be practical to use such a device for the small amount of salt used by each local council. --Tango (talk) 12:55, 7 February 2009 (UTC)

A concern with using salt for de-icing, is that the salt may enter the ground water, and increase its salinity. --NorwegianBlue ^talk 12:13, 7 February 2009 (UTC)

There's an alternative explanation - that is shoddy reporters trying to make a story and distorting the facts. Rock salt for roads is kept under cover in the UK. It can cake. Perhaps the reported imagines it has to be thrown away like rancid milk? Answer - ignore UK news reporters - the quality isn't there.87.102.43.12 (talk) 17:04, 7 February 2009 (UTC)

By the way the UK road salt almost certainly comes from cheshire salt mines which are operated by http://www.compassminerals.com/index.php?option=com_content&view=article&id=46&Itemid=1 - you could contact them and ask them about it.

A more likely explanation is that the councils don't have sufficiently large storage facilities for salt in the event of a lot of snow. But the truth is something nobody is interested in nowadays it seems. —Preceding unsigned comment added by 87.102.43.12 (talk) 17:13, 7 February 2009 (UTC)

I forgot to say take the news with a pinch of salt (triple pun at least - do I get a bonus??) —Preceding unsigned comment added by 87.102.43.12 (talk) 20:37, 7 February 2009 (UTC)

While such comments go against the grain for some people, who will assault you with an assortment of salty language, I find them entirely salient and would argue that we should double your salary immediately, and also increase your expense account, so diem payments go up, as well. :-) StuRat (talk) 19:41, 8 February 2009 (UTC)

Salt for road use in northern U.S. states is kept in covered storage. Anti caking agents may be added. Homeowners often use more expensive (3 or 4 times the cost per weight) ice-melters such as mixtures including Calcium chloride, which works at lower temperatures and which is claimed to be less harmful to concrete and plants. New concrete is especially likely to spall or develop large pits if a chunk of rock salt lies on it. Edison (talk) 21:27, 10 February 2009 (UTC)

Chemical element

I heard that there is a chemical element which makes you lough if you smelled it. What is the name of this element? —Preceding unsigned comment added by 196.200.102.42 (talk) 18:38, 6 February 2009 (UTC)

Do you mean "laugh"? Nitrous oxide is often called "laughing gas" because it has that effect. It isn't an element, though, it's a compound. --Tango (talk) 18:42, 6 February 2009 (UTC)

...And, it nitrous oxide doesn't make you laugh. It may disinhibit, making someone less reluctant to laugh. --Scray (talk) 21:47, 6 February 2009 (UTC)

...Lafnium? Mattopaedia (talk) 13:03, 10 February 2009 (UTC)

Ants

I heared some where that ants can speak just like humans . i want to know , if that is a truth and if it was mentioned ome where in the old times science , please back your answers , thank you ..? —Preceding unsigned comment added by Mjaafreh2008 (talk • contribs) 21:22, 6 February 2009 (UTC)

In a word, no. Ants communicate, to be sure (see the relevant article subsection), but not in any way that could be characterized as speech, and certainly not "just like humans". — Lomn 21:31, 6 February 2009 (UTC)

If you were a Honey bee you would communicate by strutting and shaking of the bootierearendus ~ R.T.G 23:48, 6 February 2009 (UTC)

To be a little more explicit here, while ants communicate with each other on a fairly intricate level, they don't "speak" in any real sense of the word: they can communicate things like "danger, there's an enemy here" or "follow this scent trail to reach some food", but there's no exchange of ideas. They have no opinions, moods, plans or friendships, and no way to comprehend or communicate these concepts. -- Captain Disdain (talk) 00:44, 7 February 2009 (UTC)

"They have no opinions, moods, plans or friendships, and no way to comprehend or communicate these concepts." Do you have a source for that, or are you just saying that because you think those are characteristic of humans? --99.237.96.81 (talk) 20:11, 8 February 2009 (UTC)

Well. Let me expand on this a little, since you ask:

Opinions are pretty complex things. "I'm hungry" or "I like carrots" are not opinions, for example; opinions require at least some degree of abstract and conceptual thought.

Moods kind of fall in the same category: they require a pretty advanced sense of continuity and self, as well as an ability to put yourself in a larger context. Being in a certain mood is not the same thing as experiencing a similar emotion -- which ants may also not be capable of, but let's leave that for the sake of the argument. Perhaps an ant can feel fear, for example, but you won't see an ant gripped by a long-lasting sense of melancholy, anguish, or camaraderie, or a pure joy of being alive. Ants don't have grumpy days or happy days, they just have days.

Plans, again, require abstract thought: "must get food" is not a plan, it's an instinct. Granted, ants can do pretty complicated things, but that's not the same thing as an ant actually sitting down and thinking about how to go about building an anthill in advance, never mind working it out with its co-workers.

And finally, friendships. It makes no difference to an ant which worker ant it's hanging out with, or whether it ever sees a specific ant again. An ant will not go without food so that another ant will eat, or do extra work so another ant can rest, or consistently strive to work with specific ants, or stop working just to hang out with another ant for ten minutes, for example.

But do I have references that specifically state that this is the case? Not as such, no -- although that has very little to do with what I believe to be characteristics of humans, thanks for asking. But then, it's often hard to prove a negative. In everything I've ever read about ants (or any insect, really) -- and I readily admit that I'm no expert -- I've never seen any mention of them evidencing the kind of behavior described above. It is, of course, possible that they do that kind of stuff all the time, and nobody's ever noticed, but that strikes me as unlikely. It's also possible that there is evidence of this kind of stuff, and I'm just completely unaware of it (as is most, if not all of Wikipedia), but that doesn't strike me as very likely either. In any case, I certainly can't prove very well that ants are as I say they are, but I think the burden of proof would be on anyone who claims that they are capable of more than is generally accepted, on the basis that extraordinary claims require extraordinary proof. (By the same token, you probably can't prove that I'm not an astronaut, but it would be idiotic to expect you to believe it without some sort of proof.) -- Captain Disdain (talk) 04:21, 9 February 2009 (UTC)

Ants do communicate specific messages by sound. This has recently been shown by playing back recordings in a nest and watching the response, but this is only "speech" in the same way that dogs talk to each other by barking. Dbfirs 12:48, 7 February 2009 (UTC)

If an ant had a random variation in its genome allowing it to speak, would you still call it a mute ant? Edison (talk) 21:11, 10 February 2009 (UTC)

Oh, Edison! Stop talking. -- Captain Disdain (talk) 13:39, 12 February 2009 (UTC)

Immunisation through constant exposure

I read in a magazine that people who nibble at their fingers since their childhood tend to have stronger immune systems, because their body has become immune to hundreds of different bacteria which have penetrated the body through the "easy entrance" provided by wounds caused by nibbling. Therefore, their immune system would have developed defences against many pathogens that other people have not.

Nevertheless, the reputation of the magazine is quite dubious and I don't know whether to believe it. Is it right? Half-right? Completely wrong? Thank you! Leptictidium (mt) 23:53, 6 February 2009 (UTC)

At best such a study can show a correlation but it would be really hard to show causation. Nimur (talk) 00:29, 7 February 2009 (UTC)

It is hard to say whether the statement in the magazine is right or wrong; as far as I know, the exact details of adaptive immune system development during childhood are not yet well understood. You would want to read the adaptive immune system article, and especially the paragraph on immunological diversity. You can then follow the links. What it basically says is that the initial diversity of antigen receptors is probably combinatorial in nature, and not related to early exposure. However, an exposure to a specific antigen usually leads to stronger and faster response to that antigen on subsequent exposures. We also have an article on Hygiene hypothesis, which says that the people exposed to wider range of pathogens during childhood will have weaker autoimmune or allergic responses. Finally, there is an inherent sampling bias; namely, children with weak immune system growing in poor hygiene conditions are less likely to reach adulthood than children with equally weak immune system that grow in a more sterile environment. Bottom line, we probably just don't know enough about our own immune system just yet. --Dr Dima (talk) 01:35, 7 February 2009 (UTC)

Electrons and magnets and monopoles

I'm having a little trouble understanding the differences between something like an object with a charge, and magnets. Like if you rub a plastic rod with a cloth, it gathers electrons and becomes negatively charged. But it's not a magnet right? The plastic rod still has a magnetic field doesn't it? Would a negatively or positively charged plastic rod attract ferromagnetic objects like iron? And finally what's the difference between say, a hypothetical monopole and a positively charged mass or a negatively charged mass? Both of those charged masses would only have one charge right? ScienceApe (talk) 23:58, 6 February 2009 (UTC)

Electricity and magnetism are not the same thing. The two can interact, and each can cause the other, but they are not the same. It sounds like your confusion stems from this simple misunderstanding - so let me reiterate in no uncertain terms: electricity is not the same as magnetism. You might be interested in reading electric charge, that is a good place to start. Nimur (talk) 00:32, 7 February 2009 (UTC)

I'd argue that they are both manifestations of the same fundamental force, electromagnetism. StuRat (talk) 09:09, 7 February 2009 (UTC)

I agree, but the question is about macroscopic manifestations. It seems like the questioner has confused electrostatic attraction with ferromagnetism. Nimur (talk) 16:52, 7 February 2009 (UTC)

Usually magnetism is ascribed to all the electrons (or whatever) having the same spin (physics). (or having more of one type of spin than the other - statistically)

In general for an electric current consists of electrons with the same spin (hence the magnetic field due to the current). (At least a current produced electromagnetically)

It's common for the spin of an electron to be considered a different quantity to the charge - rather than being equivalent to the charge. (for instance the spin of an elctron can change sign but the charge of an electron cannot)

HOWEVER - the properties of charge does show some similarities to that of a 'spin particle' - for example the magnetic field associated with a moving charge - is similar to that expected from a spin particle that is along the same line of movement.

This can lead to confusion.

Hopefully someone can explain why electric current (moving charge) has a magnetic field but, a static charge does not have a magnetic field. Possibly this is not true - I've never tried to see if there is a magnetic field associated with static charge - it could be very weak under typical conditions (if it exists at all). If it was there this would simplify the answer to your question. Hopefully someone can put you (and me) out of our ignorance. —Preceding unsigned comment added by 87.102.43.12 (talk) 14:21, 7 February 2009 (UTC)

(as for the monopole question - I really don't want to attempt to answer this because I know someone will come and shout "monopoles dont exist at me" - still you could consider negative charge to be a south monoopole, and positive charge to be a north monopole. - in this example a monopole being a thing that has 'spin' symmetry - literally only left or right handed chiral symmetry - with otherwise perfect spatial symmetry (or a point object).)

Hope that you are familar with 'spin' otherwise that may read as gibberish.

Positive and negative electric charges are electric monopoles. Magnetic monopoles don't exist (or, at least, haven't been observed yet). You should probably read up on magnetic moments, it's not as simple as electrons all spinning in the same direction. --Tango (talk) 20:10, 7 February 2009 (UTC)

The comments above (starting with the one by 87.102.43.12) are riddled with misconceptions and imprecision. The reader might better ignore them because they are more likely to add confusion then insight. Dauto (talk) 19:21, 7 February 2009 (UTC)

Right. The earlier comments about spin seem incorrect. If you're feeling brave, read multipole expansion for rigorous explanation of exactly what a monopole is (...constant term independent of any spherical harmonic function, thus acting independently of the direction to the observer...). Magnetic moment, including single particles with quantized spin, do not qualify as a monopole. Nimur (talk) 10:47, 8 February 2009 (UTC)

(Isn't "literally only left or right handed chiral symmetry - with otherwise perfect spatial symmetry the same as "independent of any spherical harmonic function" the same thing), also mulptipole expansion doesn't explain what a monopole is - though it does explain what it isn't. I added that a particular type of monopole has 'handedness' - not necessary for a monopole as such - but necessary as an explanation of some of the properties of the electron.

If you're not familar with such an object I suggest you ask on the maths desk about the expected properties of such a symmetry group - you may find it interesting. Good luck. —Preceding unsigned comment added by 87.102.43.12 (talk) 14:05, 8 February 2009 (UTC)

A piece of plastic PVC pipe rubbed with a piece of wooll acquires an electric charge. It will then attract uncharged or oppositely charged insulators (like glass or plastic) or conductors (like metal). But it does not have a magnetic field as a result of the stationary charge. Edison (talk) 21:09, 10 February 2009 (UTC)