Wikipedia:Reference desk/Archives/Science/2007 July 31

= July 31 =

Turning the Pampas into forest
As the wikipedia article on the Pampas suggests, the only reason that the more humid part of the Pampas doesn't have a deciduous forest like its counterparts in the north temperate regions have is because of edaphologic reasons, e.g. the ground being too compact to allow tree growth. My question is, if people were to plant extensive parts of the Pampas with trees, would the soil eventually break up enough to allow trees to grow naturally, so that native species of trees that are only present along riversides to colonize areas away from rivers?

Thermo Wells
How do temperature gauges mounted in thermo wells work? Also, i would like to know about the construction of thermo wells.


 * Looks like we need an article on thermal blanket - which is the general term. A thermal well is a "deep" thermal blanket based on the same technology. -- Kainaw (what?) 12:45, 31 July 2007 (UTC)


 * OK - created the article. As for the temperature gauge, it appears to just be a regular thermostat.  If the soil is too cold, it increases the heat.  If it is too hot, it decreases the heat. -- Kainaw (what?) 12:55, 31 July 2007 (UTC)


 * The OP may have been asking about Thermowells, which are used to hold, mount, or protect thermocouples. That's the meaning that I'm most familiar with.


 * Looks like we need another article for thermowell. -- Kainaw (what?) 14:31, 3 August 2007 (UTC)


 * Done. -- Kainaw (what?) 14:36, 3 August 2007 (UTC)

How MUCH air moves with the wind?
Short: I'm working on a simplified weather simulator, and having trouble finding information about how much -- what volume, mass or molar quantity -- of air moves with the wind caused by pressure differential.

Detail: I'm making several gross simplifications in my sim, and using a lot of descrete time, quantity, etc., units where the real answer is more differential than that. So I've got, let's say, a column of air in my atmosphere. To simplify, let's say this column is isolated -- we won't worry about the columns surrounding it, and just talk about up & down in THIS column. At some point in the column, I have a cubic meter (let's say) of air that is 772 mmHg. The "next" M^3 of air up in my column is (let's say), 762 mmHg. I want to "mix" these two bodies and, using PV=nrT, I know that -- once everything settles out -- the two air-masses will try to move toward their "average" of 767 (assuming no other forces, like the remainder of the column.) There is also mixing of temps, proportionate to how much each air "bucket" contributed, etc.

So far, so good. I've got this much "down."

What I DON'T know is: let's say that, rather than a M^3, my "buckets" are 10kM^3 -- so now it's easy for me to see (imagine?) that this exchange/transfer/equalization takes some amount of time. There's not just an instantaneous "poof" and it's over. And that, btw, is "wind" (although, in this case, the "wind" I'm describing is vertical, and more likely called "convection.")

So my question is: once I've figured out how the two adjacent "buckets" of air are going to try to equalize (the "easy" part), how do I figure out how long it will take for that exchange to take place (the question part)?

Is there some sort of "amount of air that will flow past an area size A in an amount of time T, given a pressure differetial ΔP" formula?

Thanks! Oliepedia 15:09, 31 July 2007 (UTC)


 * To solve this I'd recommend considering the mean speed of the gas particles across the pressure boundary - looking at ideal gas or gas laws might lead you to find an expression for this but I think it's something like sqrt(RT/?m) times a constant - you can consider the number of gas particles going in one direction and the number going in the other direction to give the change in pressure etc after a small period of time.


 * Right. That's basically my question: what is this formula?  I haven't been able to find it under and of the gas-law sites, ideal or otherwise.  (For my purposes, I'll be using ideal, and ignoring the fact that things aren't ideal in my sim.) Oliepedia 00:10, 1 August 2007 (UTC)
 * You can find it here Root_mean_square
 * You'll probably need the component of that in one direction, I think that's 1/sqrt(3)


 * Next you need to be able to convert an expression for "amount of air that will flow past an area size A in an amount of time T, given a pressure differetial ΔP" into a differential equation and hopefully solve that. (not necessarily easy or do-able)


 * That's one of the short-cut simplifications I plan to make in the sim, too -- that I'll be doing this with descrete time (i.e., 1 minute's worth at a time), vice doing actual differentials. Oliepedia 00:10, 1 August 2007 (UTC)


 * to summarise find (or ask about) an equation that gives the velocity of gas molecules across an area in terms of p,T,gas type. Then find the change on either side of the boundary to get the new conditions (you'll need to take into account the average energy of the molecules on one side and the molecules that have moved in), next solve this eqaution (it's a differential equation - maths desk might help more).


 * Did that supply the missing info?83.100.252.241 17:37, 31 July 2007 (UTC)


 * Sort of. The thing I'm missing is the "how much air moves in a given time period?" part.  Oliepedia 00:10, 1 August 2007 (UTC)


 * As for your question about the computer sim - I'd recommend (once you've got a solution for AxAxA buckets) splitting up your 10000Ax10000Ax10000A buckets into buckets of size A, and finding the change in each small bucket in time t. Then run the simulation and observe what happens.?83.100.252.241 17:45, 31 July 2007 (UTC)


 * Right. THAT part I understand.  I just can't seem to find the "how much air should I be moving around for a given time period?" formula, and I'm not sure where to look.
 * Thanks! Oliepedia 00:10, 1 August 2007 (UTC)

Perhaps a better restatement of the question
An example: Let's say I have a box, volume V, pressure P. I have another box, volume V', pressure P'. I put them together and open a hole between them area A. The ideal gas law tells me how to figure out how the two boxes will eventually reach equillibrium. My question is: What is the formula for figuring out how the pressures changes over time? Or, if no one knows that, what is the forumula called? Or what sorts of terms do I want to put into Google? I'm not even sure what to call what I'm looking for, here.

Thanks! Oliepedia 05:14, 1 August 2007 (UTC)


 * Broadly speaking, you may be looking for Bernoulli's principle, which governs quasi-equilibrium flow of fluids as a result of pressure changes. For fluids of constant (or nearly constant density), it says:


 * $$ {v^2 \rho \over 2}+\rho g h+p=\mathrm{constant}$$


 * where &rho; is the density, v is the velocity, h is the height, g is the gravitational acceleration (9.8 m/s^2) and p is the pressure. To the degree that viscous dissipation (e.g. turbulence) can be ignored, these terms must sum to the same constant in all parts of the fluid.  So if you know the density, pressure, and height in all regions, you can solve for the changes in velocity (e.g. wind).  In the real atmosphere, it is worth noting that both pressure and density vary with height, and solutions of this equation need not imply that all regions have the same density or pressure.  (Note the article contains a more precisely formulation that also implicitly allows for the effect of temperature changes, as well).


 * This is a quasi-equilibirum description which means it only really works for changes that are relatively small in spatial/time scale and neglects various drag and other components of the evolution, but you only wanted a toy model to play with right?


 * To address your additional question above. Let's assume h is constant.  Also, assume that the air moving through the "hole" has the same density as the air at higher pressure.  Then by rewriting the equation we get:


 * $$ v^2 = {2*\Delta p \over \rho _{high}}$$


 * The total mass transfer will be the area of the hole, A, times the velocity at the hole, and mass will continue to flow until the pressures are equal (implying equal density if the temperatures, heights, and everything else are the same). With a bit of calculus the evolution can be worked out exactly, or with a bit of algebra you could find some approximation.  Unfortunately, I need to be going, so I'm not going to carry this any further, but hopefully that's enough to get you started.  Dragons flight 21:57, 1 August 2007 (UTC)

leather
1. Is it true to say that leather is made from the Stratum corneum or are other parts of the skin included?83.100.252.241 15:25, 31 July 2007 (UTC)

2. If so what are the forces between the dead cells that give leather/skin its strength?83.100.252.241 15:13, 31 July 2007 (UTC)

3. Can anyone supply a link that shows a microscopic picture of leather (or a diagram) showing its similarity (or remnant structures) in comparison to the skin it is made of.83.100.252.241 15:25, 31 July 2007 (UTC)

oral chelation
I need information on oral chelation both positive and negative side effects and possilbe organ toxicity especially related to kidneys.


 * See our article on chelation therapy for some information. Note that oral chelation therapy has not been found effective in clinical trials. TenOfAllTrades(talk) 16:52, 31 July 2007 (UTC)

Size of Euro Banknotes
What ios the logic behind the selection of the size of euro banknotes. —The preceding unsigned comment was added by 202.70.64.15 (talk • contribs) 17:45, July 31, 2007 (UTC)
 * Euro banknotes - larger notes are worth more? was there something more specific you were thinking of?83.100.252.241 17:48, 31 July 2007 (UTC)
 * Different sizes also make it easier for people with impaired vision to distinguish notes. Flyguy649 talk contribs 17:52, 31 July 2007 (UTC)
 * Also, very large or very small notes would be rather inconvenient, both for people and for machines (such as ATMs and cash registers) that need to process them. Combine this with the desire to maximize the size difference between different notes (to make them easier to tell apart) and you'll probably get something fairly similar to the sizes actually selected.  —Ilmari Karonen (talk) 22:37, 31 July 2007 (UTC)


 * Well, in the US, where all the money is the same colour, that would make sense, but euros are coloured differently. DirkvdM 05:59, 1 August 2007 (UTC)


 * Most countries banknotes are coloured differently but are different sizes. Both features help people (and machines) differentiate different denomination banknotes from each other. Also, as you pointed out, it's far easier to see the different denomination notes when they are stacked in a wallet, pile, cash register, etc Nil Einne 13:01, 1 August 2007 (UTC)


 * But as anyone from the US or Canada knows, when they're all the same size, they're easier to handle: it's easier to make a stack from mixed bills, or put them in a wallet, without losing a small one in the middle. Really, the Swiss have it right.  Their bills are different lengths for each denomination but all the same width, so they stack well and can be distinguished by size (and color).  It's a great shame the people who designed the euro bills didn't copy that. --Anonymous, August 2, 2007, 04:20 (UTC).


 * One advantage is that it's easy to pick a certain size out of a wallet. I've got 5, 10, 20 and 50 euro notes in my wallet, ordered by size and the higher nominations are easily distinguishable from the lower ones when I open the wallet. No need to fumble about. DirkvdM 05:59, 1 August 2007 (UTC)


 * If you see not properly or you are colour blind size would be a good help for you.--Stone 11:41, 1 August 2007 (UTC)
 * What happens if you are dimensionally challenged? -- JAXHERE  | Talk 15:10, 1 August 2007 (UTC)


 * You mean a topologist? DirkvdM 06:55, 2 August 2007 (UTC)

What is the difference between light and EM energies besides frequency?
others have dodged this question rather then replying it. To say that light is quantized (photons) and EM is not does not answer the question.


 * That isn't an answer because it is not true. See electromagnetic spectrum.  The difference is frequency/energy.  Notice (when you read the article) that frequency and energy are related based on Planck's constant. -- Kainaw (what?) 18:08, 31 July 2007 (UTC)


 * (EC) There is no difference; visible light is a kind of electromagnetic radiation (that is, it is EM radiation with a particular frequency). It's like asking "what is the difference between an apple and a piece of fruit?".  --TotoBaggins 18:12, 31 July 2007 (UTC)
 * That's right - light is EM radiation of a certain frequency. Other measures are used (wavelength and energy) but these three things are directly related (energy is proportional to frequency and wavelength is inversely proportional to them). In other words all light and EM radiation can be described by a single variable - the frequency (intensity is the amount of it).
 * Thats the current level of understanding (ive not included polarisation).
 * Different frequencies of EM radiation interact with matter in different ways. The energy of light wave matches the difference in energy between outer electron orbitals, so that it can be absorbed or emmited by this mechanism.  X-Rays have similar energy to the inner electrons in atoms, and so can knock out those electrons.  Gamma rays have energy in the realm of nuclear transitions, can so can get a nulceus into an excited state if it is the right frequency. GB 11:03, 1 August 2007 (UTC)
 * From Light: "Light is electromagnetic radiation with a wavelength that is visible to the eye." The 'eye" here is unspecified, so what is light to a bee is invisible ultraviolet electromagnetic radiation to a human. What is invisible infrared to a human may be used by a Pit viper to track its prey. The part of the EM spectrum which is "Light" for humans is about one octave, if you picture a long keyboard with keys stretching to a practically unlimited distance to the low frequency and high frequency directions. Having a tiny band of visible wavelengths makes the task of focussing and creating a sharp image easier for the eye than if longer and shorter wavelengths had to be formed into an image. Distinguising these hues or seeing these colors may have some special survival value compared to a higher or lower frequency band. See also Visible spectrum. Edison 17:41, 1 August 2007 (UTC)

Vitamin Scare
I wanted to start to eat healthy and make sure that I was getting all the vitamins I need on a daily basis. I decided I will buy some mutlivitamins and take them during dinner everyday. However, an alternative medicine expert (well, I don't know if she is really an expert) informed me that some of the vitamins in the multivitamins are not absorbed in my body because either they need to be in another form (liquid), or they need to be taken seperately or they are counteracted by another vitmain. Also, she informed me that, in fact, some of the vitmins are too dangerous for me to take. Does anyone have any facts on this? Would it be beneficial to even bother taking these mutlivitamins? --WonderFran 19:40, 31 July 2007 (UTC)


 * See our Vitamin supplement article for general information, but do not treat it as medical advice. If you want medical advice, see your doctor. --Heron 20:33, 31 July 2007 (UTC)


 * Experts in alternative medicine are generally, by definition, not experts in actual medicine. 151.152.101.44 21:13, 31 July 2007 (UTC)


 * I do know that a lot of calcium pills are made from sea shells, and people claim those aren't easily absorbed by the body compared to other sources. But then again, the competitors of the sea shell variety claims most of that, so I'm not sure if that's even to be trusted. --Wirbelwind ヴィルヴェルヴィント (talk) 21:14, 31 July 2007 (UTC)


 * I have removed medical advice provided by anonymous user 80.2.221.47. Please do not give ask for or give medical advice here. We cannot know all the facts regarding this person; even beyond any legal liability, it would be stupid to attempt a diagnosis based on a few lines of text. Matt Deres 22:51, 1 August 2007 (UTC)

TECH CHALLENGE - The missing Ni-MH battery- Can you find one ? In america? of power to run a car?
Information has it that some oil companies have bought control of the company that owns the patent on the Ni-MH battery of the type that was used to power the GM EV1 and the Rav4Ev types; and are not allowing anyone to make the higher power ni-mh's (they are only allowing the smaller types that you would use in your phone, etc. The story goes that Detroit and the Oil companies are delaying the electric car (full size) because they don't want to lose the money in oil and for detroit, parts sales for ICE types. FYI:  Some RAV-4 EV's that were "saved" from the recall actually still are using the same Ni-MH "green" batteries as were original equipment and get up to 100 miles on one charge that costs about 30 cents. (GM actually had some people put in jail they say for not letting them crush their recalled cars the ev1) To test the assertion we tried to buy a 12 volt Ni-MH battery in the USA. So far after a week, no luck. Big runaround? Everyplace says they will get back with us but either say they can't or give us phone numbers that don't work, or don't answer. Is it true? Can anyone find a 12 volt Ni-MH battery of the power (ie 75-125 amphours) for sale? Thanks! If you can you are truly blessed. Give me the link or phone to this place. Please don't put up battery finder websites.. they never have what we need (12v @ ~100amphours). An actual link to an actual seller of that actual product is what is needed. 209.16.117.50 20:15, 31 July 2007 (UTC)209.16.117.50 20:22, 31 July 2007 (UTC)

Tape 40 - Makita 3 amp-hour batteries together. If nobody has built the car, why would someone have built the battery? So I think your theory is urban legend, if that. There doesn't need to be a conspiracy to sell oil. pLenty of people want/need it. --Tbeatty
 * I'm not saying there is any conspiracy (I think it's silly, a variety of people may have their own reasons for something and may work to it, but it doesn't mean they all meet up and agree to some vast conspiracy). However to presume that just because there is a high demand for oil (which there is) means that there is no reason why those who would profit from oil won't want to try and stop developments which may lesson the demands for oil is a plain silly. If the electric car was a success (which is a big if) then it's likely it would have reduced the demand for petrol for cars and also the overall energy consumption by cars. Cars are clearly a not unsubstanial contributor to the demand for oil. It's resonable to assume then that if electric cars were successful enough, there would be a noticable drop in the demand for oil. And it's resonable to assume that the companies who make money from said oil won't want this to happen. This doesn't mean they actually did anything, but it does mean that it's a bit silly to say that because there is a large demand for oil from other sources, no one is going to care about the demand from cars Nil Einne 15:12, 1 August 2007 (UTC)
 * It's a false premise on the mistaken belief that these is a monopoly. Car companies would not halt the development of new technology because it competes with old technology.  Only in a monopoly would this happen.  Take the Prius.  It is a huge competitive advantage to Toyota and they developed it to exploit the new market and gain market share over their competitors.  Lacking in marketing foresight is not the same as inhibiting development.  IF GM could build and sell a car for a profit that ran on cow dung, they would do it.  The problem is that market analysis says they will not get the volume of scale necessary to support the development.  Once that changes, a car maker will make the cars.  GM doesn't make money by keeping the price of oil high, they make money by beating other auto manufacturers and that requires making correct investment decisions for future cars.  If electric cars are viable, someone will make them and sell them (just like Toyota Prius).  Sometimes prodcuts come before they are ready and they are not viable so they are cancelled (GM EV1, Apple Newton, etc).  This is basic free market economics.  Oil companies also compete and the are all looking for new markets.  I'm just guessing, but Hydrogen cracked from petroleum will probably be the cheapest source for hydrogen batteries so batteries are potentially a huge market for oil compaines.  The Green hydrogen from water will probably be the most expensive.  --Tbeatty 16:08, 1 August 2007 (UTC)
 * Incidentally, "auto quality" is a historical analysis that you can use to test this theory. 20 years ago, a similar argument was made that GM/Ford/Chrysler built crappy cars on purpose because they wanted the consumer to have to buy a new car ever 2-3 years.  When Japanese cars started to sell quality, it became apparent that this was not a viable strategy (if it ever was).  The reason that quality was not higher was becasue consumers were indifferent to the quality differences on the car market until Honda/Toyota started selling very reliable cars and htis became a significant market segment.  There are still quality differences between models but it's market segmentation that drove quality in both the current and previous generation.  Competition improved the product even though on it's face it would seem each company would have lower costs if they sold crappy products.  Cost is only one side of the equation and revenue is the other.  Car makers will build cars if revenue-cost=significant profit over the risk free rate of return of the investment.  It could be widgets, or electric cars or SUVs.   --Tbeatty 16:17, 1 August 2007 (UTC)

See also Electric car and watch Who Killed the Electric Car?. DMacks 01:12, 1 August 2007 (UTC)

12V at 100 Amp-hour is equivalent to the energy generated by a 150 horsepower engine in 40 seconds. You'd need about 3 orders of magnitude more energy to have a realistic product on the American market. Dragons flight 02:20, 2 August 2007 (UTC)

The fact that no one has yet found a "verified" source for the automotive or golf cart sized (fits electric vehicles too) 12 volt @ 100 amphour battery lends credence to the theory that GM sold the patent to OIL so they could sit on it and make sure the electric car is delayed. The 150 HP is nice but EV's only need about 30HP and when you put 10 of the 12volts in series thats about what you get. Other countries have growing numbers of electric cars and make this type battery. France makes millions of them, england has many electric car (some whole towns have mostly converted), yet the patent is a USA one and we don't have that battery? What gives? FYI; The Ni-Mh battery lasts almost forever (10-20 years and more), is green, is maintenance free and gives car a range of 100 miles. Yet we can't get it and are forced drive the dirty gas guzzlers or use poor lead acids, or ni-cads (very difficult to maintain). The makita 3 amp battery someone mentioned is 97 amps short of what used to be available in this country in year 1999. Please don't send a list of batteryfinder websites. We need a real verified phone number or person to contact to get this battery. TripleBatteryLife 15:35, 2 August 2007 (UTC)
 * Patents are all public. You can search for them at www.uspto.gov.  Patent applications are public as well.  Nobody is sitting on the patent or delaying techology.  The Smart EV in England is probably the closest thing and it is not available in the U.S. since it doesn't pass the crash tests (thank Raplh Nader for that).  A redeisgned FourTwo is avaliable in January here --Tbeatty 02:22, 3 August 2007 (UTC)


 * Our article says that the EV1 used either 26 12-volt lead-acid batteries holding 67.4 MJ (18.7 kWh) of energy or 26 13.2-volt nickel-metal hydride batteries which held 95.1 MJ (26.4 kWh). That's more like 60/77Ah than 100Ah per battery - but still pretty impressive.  The article says that the Lead/Acid batteries were made by Delco and Panasonic and the NiMH batteries were 'Ovonics'.  The Ovonics article says that these EV1 batteries are still in use in many Hybrid vehicles today.  Far from being supressed by big oil - these batteries are in hundreds of thousands of modern cars and (wonder of wonders) Chevron Corporation (aka 'Big Oil') are actively partnering with Ovonics on improving hybrid car batteries.  So where is the big mystery?  Good old fashioned lead acid batteries that at least two companies know how to make - fancier NiMH's were from Ovonics who make and sell them for modern hybrid cars.


 * So nothing was supressed? There is no mystery!  Even if some mysterious technology does exist - you say that it's patented!  OK then!!  That means that you can read the patent and find out exactly how they work.  I'm very, very, skeptical of claims that such-and-such almost magical technology was 'supressed' by some mystery organisation.  GM's business is making cars.  If they had a fully workable, cheap, usable electric car technology - it would make them unbeatable in the car market.  For this mystery "OIL" company to buy the technology would have to have have resulted in a spectacularly large wad of cash being transferred.  Since most (if not all) big oil companies - and GM - are publically traded companies, any deal that big would have shown up in their books - and would be a matter of public record.  In short - the combination of the publically available patent and the public records of the money paid for it would make for a REALLY public supression - not some kind of sneaky back-door transaction.  We'd know about it - it would be all over the mainstream press.   It's not - ergo it's bullshit.


 * As for "some whole towns have mostly converted" to electric cars - I'd like to see your source for that - because I'm pretty sure this is news to English people!


 * The General Motors EV1 was an experiment - that's why they only leased them - never offering them for sale. The experiment failed - the cars were awful!  According to our article, the batteries wouldn't produce enough current in low temperatures - confining it to 'warm weather' states - they took far too long to recharge - and they had to be replaced every 25 to 30,000 miles!  The cars were two-seaters only they needed special skinny tires that were dangerous at high speeds.  It's A/C was notoriously poor - (which wasn't good in 'warm weather' states).  Far from having a magical battery technology EV1 was doomed when the expected breakthrough in battery technology did not take place - (that quote comes from GM themselves!)  SteveBaker 02:23, 3 August 2007 (UTC)
 * The concern for GM in keeping the EV1 was liability. These cars became hazards to rescue personnel, victims and the environment.  GM was rightfully concerned that when the cars started to go bad and the proper parts were not available for repair, the cars would become a huge liability in an accident or as a hazardous waste disposal problem.  Therefore, GM chose to destroy them and dispose of them properly rather than risk the inevitable lawsuit.  Smart decision if you are a shareholder or Detroit resident or a future victim.  --Tbeatty 02:59, 3 August 2007 (UTC)


 * Nightmare scenario for GM: idiot hollywood actor/actress making a statement with their unsupported Electric Car gets it repaired by high school dropout mechanic at the corner. hollywood actor/actress is unaware of fault in charging system that energizes the chasis and they electrocute themselves on their way to a Paparazzi party.  These are people that repeatedley drive while intoxicated or with suspended licenses after multiple citations.   The last thing GM needs is that person dealing with an broken/ill-repaired electric car.  --Tbeatty 03:07, 3 August 2007 (UTC)


 * Here's a company that makes the drivetrain for the electric Smart Car.--Tbeatty 02:26, 3 August 2007 (UTC)


 * appear to be the manufacturer of the EV1's NiMH batteries. This paper says that they have a battery pack that produces 122V/3.7kWh for an electric motorbike.  Not as much as the EV1 battery pack - but much smaller. That's presumably 10x12.2v cells - so each cell is making 12.2v/370Wh - quite a bit better than EV1's individual cells - about 10x better energy density than a lead/acid car battery.  So - no conspiracy - no mysterious big oil buyout.  They probably won't sell you batteries in small quantities though - they aren't consumer-oriented.  They sell technology licenses to car companies and such. This may well explain why they don't bother to reply to your requests. SteveBaker 03:26, 3 August 2007 (UTC)

STILL WAITING for a valid answer ( a phone or webpage that is an order form for the NI-MH.  The ovionics answers were the most true but still Ovionics seems to have had to switch to Nickel Hydroxide types (is that the same as Nickel Metal Hydride).  Even so I don't see where to order them.  I couldn't get your second web page to come up?  Thanks for trying.   Also the SMART car is made overseas and gets batteries overseas (NOT USA).  The EV1 had rave reviews from all users (see the DVD "Who killed the Electric Car" ).  GM employees said it was the easiest car to maintain and repair ever; saying they had to only rotate tires and send them back out.  As for safety: The electric is much more safe than gasoline (can you imagine gasoline all over the place in an accident? When I was in germany on the autombahn they had these high speed wrecks that invariably ended up in a Huge Fireball! No one much survives these nightmares. BUSH put out a Mandate of something like $100 million to further NOT the EV, NOT the safest car on the road, Not the one that makes you NEVER have to go to gas station ever again, but the very dangerous HYDROGEN CAR. The HC only gets 63 miles before having to fill up again, H is very expensive, and its very very very dangerous. But Detroit and BIG Oil know this and that it will take 20 years to get one into mass production and then it might well fail for being a safety hazard. The EV works now and it drastically reduces Detroit and big Oils profits (off your back) so they are "alleged" to be working very hard against it.
 * Isn't it strange that the rest of the world is switching to EV's EXCEPT the USA? Isn't it strange that even foriegn ICE's get up to 52 MPG and more while we typically get, what, 20? 3o? maybe?
 * As for the the performance as I said it got rave reviews which GM ignored. For ac, yes I would agree it might not have been very good,  (RAV4 EV (also out of production ) used a separate heater /ac system. )  But the rest of what you say is erroneous:  the lead -acid  batteiers are very poor performers.  Thats why they put in the Ni-MH which surprised them with how good they were.  This made them realize very quickly that the era of the gas car could fade quickly.  ANYWAY to dispprove this we are simply asking a simple question: WHERE DO YOU BUY NI-MH 12volt @ 75-125 AmpHour batteries MADE IN USA?   Ovionics?  What is order form page?   What is order phone no? Are the Ni-MH?  fyi:  They say that the Ni-MH patent runs out in 2010 .. we'll see probably a  massive switch over to them at that time.  (same reason they use em in cell phones, and laptops, is same for EV's. they WORK TOO TOO TO GOOD !!  ).
 * ANYWAY to dispprove this we are simply asking a simple question: WHERE DO YOU BUY NI-MH 12volt @ 75-125 AmpHour batteries MADE IN USA?  Ovionics?  What is order form page url ?   What is order phone no? Are the Ni-MH?    Thanks for any help (without snide comments) anyone can give!TripleBatteryLife 12:01, 3 August 2007 (UTC)
 * Search for this: WB12130HPB-FR. It's available here for a little over $200.    --Tbeatty 19:09, 3 August 2007 (UTC)
 * I don't see why TripleBatteryLife's inability to buy one of these over-the-counter causes all of these conspiracy theories.  These things are made by huge companies and are sold to huge companies.  It's simply not worth the hassle to them to sell in small retail quantities.   That doesn't mean that there is a big conspiracy - it just means that they don't find it attractive to do business that way.  The attraction of hydrogen over electricity is subtle.  When your car only has a range of 100 miles, you've got to have a way to refill it at the side of the road in (say) under 10 minutes.  None of the battery technologies can do that - they all take hours to charge up - and nobody wants to sit around at the "gas station" (electricity retail outlet?!?) for 4 hours on their way home from a longer-than-expected trip.  The only way you can fix that with electric cars is to swap out the entire battery pack at the "gas station" - but that too has severe issues with who replaces worn out battery packs and such.  You could fix that - but it's problematic.  The nice thing about hydrogen cars is that they could (in principle) be refilled in minutes - just like a gasoline powered car can.  One of the attraction of hybrids is that you could charge them at home - drive on electric power for short trips - and have the gas engine turn on when you have further to travel than batteries alone will take you.  This has been possible even with the Prius using aftermarket recharger kits...it's a bit of a mystery why the manufacturer won't sell you one of those. SteveBaker 19:33, 3 August 2007 (UTC)

Thanks TBEATTY it was very close and a valiant effort! The APC co sells UPS (uninteruptible power supply for PC systems). They might work in a golf cart, or EV, or Automobile as starting battery, but I'd have to check that out. I know of a guy who tried that with Ni_cad UPS batteries, I don't think he is very happy with only 20 miles range. They may have to be designed differently and the package size is almost certainly different. The ALLEGED conspiracy is what we are trying to find out here, not to say that it is. Its strange that this Ni-MH battery is so so so good good good that they are very afraid to have it on the market. IE if APC sells it for $149 (ck website) at 96Amphour why isn't it in walmart in the auto sizes for the same or less? $65 is what most think it would be on mass mareket. The performance according to RAV4 Ev users is fantastic (10 years now with no degradation, 100-150 mile range). The li-ion while higher energy density and lighter too, also degrades over time so you would lose range in time. THe NIMH lasts seemingly forever* and can't be broken with deep discharging. The Hydrogen car is detroit and big oils dream because they know it will take a long time to get it on the road and its going to be so dangerous (big fireballs), and it also costs a fortune to fill it up and even then only goes 63 miles. DO YOU want a hydrogen car sitting in your garage next to the house where your family sleeps? I don't. They got Bush to sponsor the H Car initiative ($100MILLON) and basically did nothing with the electric car which is already here and works good. GM who bought control share of the cobasys co who bought the patent control from the inventor of the NIMH (Stanford Ovshinsky), have allegedly sold control to OIL co's who won't sell or license to anyone who isn't OEM for above small power (10amphours) models. This makes it almost impossible for any small dealers or wannabees to make EV's in america, SO THE STORY GOES! If you have the NIMH in your own ICE car for example you'd NEVER have to replace it ever again.. AMAZING BATTERY THAT THE PUBLIC NEEDS NOW! If you had it in your own EV you NEVER have to go the the Gas Station ever again! FANTASTIC! Ane we'd reduce Global Warming too! I STILL AM WAITING FOR (THANKS for info TBEATTY) for contact to the real deal, for the NIMH that is going to work for golf carts and EV'. DOES ANYONE KNOW WHERE WE CAN BUY THIS THING? TripleBatteryLife 16:39, 4 August 2007 (UT)

STILL WAITING! The deafening silence lends more credence to the theory of conspiracy. FYI: We contacted an electric car NIMH upgrade co in Ariz; "EV-BONES". They agreed that the NIMH battery for EV's must be obtained OUTSIDE THE USA. SAD! What is the reason that anyone would want to limit EV's in america? Oil? War? Money? Greed? Should all start calling our government and demanding an explanation? The PATENT system is designed to help technology progress and prosper, not to allow some greedy characters to stifle progress. Before you respond with "paranoia" please look at this new link : EVWORLD FEATURE: NiMH BATTERIES: OBSOLETE TECHNOLOGY OR SUPPRESSED EV SOLUTION ALSO THE DVD "WHO KILLED THE ELECTRIC CAR IS NOW IN YOUR LOCAL LIBRARIES, WE KNOW, WE JUST WATCHED IT.  We will never buy another Gas Car until first I get at least one electric for around town (with NIMH batteries from overseas of course!)   TripleBatteryLife 12:55, 5 August 2007 (UTC)


 * Stop posting your nonsense. If they are not available it's becaue there is no demand.  It's like a right-hand drive car or 220v kitchen appliances.  --Tbeatty 15:52, 5 August 2007 (UTC)


 * There are two ways to interpret Chevron's purchase of shares in NiMH manufacturing. One is the conspiracy theory that they are trying to surpress the technology - the other is that they are a responsible, public-traded company who can clearly see that the market for their product is shrinking - and they wish to diversify.  Diversification into NiMH's protects their business model - if hybrid cars (or plug-in hybrids or full-electric vehicles) become insanely popular then Chevron's oil business takes a kick in the head - but if they are also a major battery supplier then they are protected.  It makes an awful lot of sense for them to do that.  So far from surpressing the technology, they want to be on the cutting edge of it.  So - which of these two possibilities is true?   The easy way to tell is to look and see if they are actively surpressing NiMH development and sales?  SInce the production of hybrids using this technology is booming - and Ovionics claims that their cooperation with Chevron is fruitful...so why assume a conspiracy? SteveBaker 22:59, 5 August 2007 (UTC)

Does petroleum ether (or ligroin) evaporate fully?
I have a jar with a mixture of some lipids and either petroleum ether or ligroin (It's called "lacknafta" in swedish and I think it translates to ligroin) and I want to separate these two. If I leave the jar without a lid in a ventilated place, will all the petroleum ether or ligroin evaporate fully or will something be left behind?

Braner 20:40, 31 July 2007 (UTC) According to the swedish national encyclopedia "lacknafta" translates to "white spirit" and some synonyms include crystal oil (kristallolja), ligroin and mineral turpentine (mineralterpentin). It contains aliphatic and aromatic hydrocarbons and it can be bought at many places, including gas stations. I don't know if anyone can help me more with this information, but thanks to those who have contributed so far.Braner 22:47, 31 July 2007 (UTC)
 * Analytical grade petroleum ether should eventually evaporate completely. If there is a lot of lipid dissolved in it, the last bits of the ether may take kind of a long time to evaporate. To some extent, a careful sniff will tell you when the evaporation is complete. ike9898 20:53, 31 July 2007 (UTC)
 * Given that "Generally laboratory grade ligroin boils at 60 to 90 °" from Petroleum ether the evaporation could take a long time - why not use a hot water bath to encourage it.. (remember NO NAKED FLAMES, sparks, etc) please don't intoxicate/set fire to yourself..87.102.7.85 21:06, 31 July 2007 (UTC)
 * Curiously swedish wiki seems to think 'lacknafta' is turps substitute? Or at least links to those pages - I'm guessing you can smell the difference between the two (petrol and turps) - possible a mistranslation of the words 'mineral spirits' which could mean either. If it is turps substitute it's going to be much more difficult to evaporate.87.102.7.85 21:16, 31 July 2007 (UTC)
 * http://translate.google.com/translate?hl=en&sl=de&u=http://www.woxikon.de/swe/lacknafta.php&sa=X&oi=translate&resnum=9&ct=result&prev=/search%3Fq%3Dlacknafta%26hl%3Den%26safe%3Doff%26sa%3DN maybe it is a dual use word?
 * http://translate.google.com/translate?hl=en&sl=de&u=http://www.woxikon.de/swe/lacknafta.php&sa=X&oi=translate&resnum=9&ct=result&prev=/search%3Fq%3Dlacknafta%26hl%3Den%26safe%3Doff%26sa%3DN maybe it is a dual use word?
 * not sure at the moment what 'crystal oil' is but unforntunately the mineral turpentine will not evaporate well at room temperature, so the answer to the original question is no.
 * (I think the 'crystal oil' may mean 'mineral oil' (mineral=crystal?)

But if I place the container in hot water under a fan? Won't that make everything evaporate?Braner 17:04, 1 August 2007 (UTC)
 * I'm not optimistic - the white spirit has a boiling point well over 100C, plus it being mixed with lipids may slow the evaporation, the fan would help - since the bp is higher than the bp of water spreading the mixture out on a thin plate to increase surface area may help. Your best bet would be distillation apparatus - a still.83.100.138.237 17:20, 1 August 2007 (UTC)

commercial uses of amino acids
I'd like to know commercial uses for amino acids other than human/animal nutrition. Are certain amino acids used a precursors for making other chemicals/drugs? Any other type of use you can think of? Thanks!! ike9898 20:50, 31 July 2007 (UTC)
 * Sure, see Cysteine and CBS catalyst, a proline derivative. Rockpock  e  t  21:06, 31 July 2007 (UTC)
 * MSG
 * Polyaspartic acid can be used in water treatment and as a highly absorbent hydrogel. DMacks 02:49, 1 August 2007 (UTC)
 * Aspartame --antilivedT 05:45, 1 August 2007 (UTC)

Aircraft speed through moving air (Title updated for clarity)
I remember back in grade school, we had math problems where an aircraft is moving at a certain speed in a certain direction, I'll just say 500 mph going N. And the wind speed is 100 mph going N, so the resulting speed of the airplane is 600 mph. I learned stuff like this even in college physics. Certainlly, this is a simplification, right? There has to be cases where airplanes in the air don't gain the entirety of the wind speed due to wind direction, drag, aerodynmics, etc, right? I'm thinking that if the wind is exactly behind the plane, that less speed will be granted to the airplane due to aerodynmics or something, causing some of the force of the wind to dissipate as it flows past the plane, or that if there's an angle to the wind, there has to be some sort of sine function force pushing up or down on the plane, slowing the overall speed as well. Correct me if I'm wrong please. --Wirbelwind ヴィルヴェルヴィント (talk) 21:10, 31 July 2007 (UTC)


 * Hmm, I'm not entirely sure what you're describing. If the plane is going 500 mph relative to the wind, and the wind is going 100 mph in the same direction as the plane, then the plane is going 600 mph relative to the ground. Or is it that a plane is head north at 500 mph, then a sudden gust of south wind comes in at 100 mph, raising the plane's speed with respect to the ground to 600 mph? I feel like I'm missing something here. (Oh, and no doubt strong winds do have some complicated effects on planes, if only because they alter the air speed over the wings) Skittle 22:11, 31 July 2007 (UTC)


 * I'd think the actual variations are more the case of wind speed being very much an average. The aircraft itself is flying with respect to the air (not being pushed by the air -- the key point), wholly independent of how the air moves with respect to the ground (or how the ground moves with respect to the sun, etc, etc).  It's much the same as the puzzle about the airplane taking off from a treadmill.  Wind striking the side of the aircraft is a different case, of course, but I don't think that's really the same thought experiment at all.
 * To consider the side effect, though -- let's take a 60-unit wind 5° off the bow-stern axis (say, a tailwind) and a 5-unit wind at right angles to the direction of flight. Before we consider the side component, one aircraft travels at X+60 (relative to ground) while the other travels at X.  Now, the 5-unit side wind component of the tailwind certainly creates some drag -- say, d(5).  That airplane is now moving at X+60-d(5).  However, the other airplane suffers the same drag component and travels at X-d(5).  Seen only from the frame of reference of the airplanes, though, both merely encounter 5-unit crosswinds.  There's no way for airplane 1 to know of the tailwind unless airspeed can be compared with externally-calculated groundspeed. &mdash; Lomn 22:18, 31 July 2007 (UTC)
 * I think the only time it may not be accurate to sum them is very close to the ground (in Ground effect). Even in that case, if there are discrepencies they will be small since the initial condition is a 100 mph wind relative to the ground.  Otherwise, it's the relative mostion described above/  --Tbeatty 22:30, 31 July 2007 (UTC)


 * I don't really know enough here, but I'd think that wind would have nowhere near that effect on it. consider a boat with a sail up - it's not going to go the same speed as the wind, because there's a lot more to it than that. And the airplane's aerodynamics would probably *stop* the wind from helping it too much, the only benefit I'd think there'd be to flying something like a jumbo jet with the wind would be less resistance. Imagine an airplane sitting on a runway, with the wind to it's back, and the wheels in neutral. Surely you wouldn't think the wind there would push it at speed, so why would it happen off the ground? There's still friction involved --L onging.... 22:24, 31 July 2007 (UTC)
 * This is why I edited in the "key point". A boat moves with respect to water.  A car moves with respect to the ground.  Air pushes on them as an additional force.  An airplane, however, moves with respect to the air.  Just as a car on a dynamometer can engage its gears at power and yet not move with respect to an external frame, an airplane can fly into a headwind and remain completely stationary with respect to the ground.  Of course, for your specific example, an airplane sitting on the runway is better described as a car.  One would similarly classify a minivan in freefall as an airplane and not expect anti-lock brakes to be of any use. &mdash; Lomn 22:28, 31 July 2007 (UTC)


 * Not really. I highly, highly, highly doubt that the friction of having wheels touching the ground would stop the wind from pushing it forward more than a literal wall of air in front of the aircraft. --L onging.... 22:38, 31 July 2007 (UTC)


 * I can't figure out where you're going with the wall-of-air thing, but the proper analogy to airplane-in-air is boat-in-water, and a boat really does move at speed+current with no appreciable "lot more to it". Talking about the thrust from a boat's sails is analogous to saying that an airplane will never reach the speed of the exhaust coming out the jet engines, which is a different question entirely.  &mdash; Lomn 00:16, 1 August 2007 (UTC)


 * Just as a note, I have heard pilots say that our flights would arrive early because of a strong tailwind. The effect might not be large on a small scale but when you are flying cross-country (as I was), perhaps it adds up. The time I remember them saying that we did arrive considerably earlier than we were predicted to, maybe an hour or so. --24.147.86.187 23:44, 31 July 2007 (UTC)
 * The effect is not at all small on trans continental flights, flightpaths are designed to take as much advantage of jetstream as possible. Vespine 00:22, 1 August 2007 (UTC)
 * Quite. You have to put up with the winds whether you want to or not.  If you pull up timetables for British Airways flights from London (LHR) to New York (JFK), you'll find that the average eastbound flight (to London, travelling with the jetstream) is nearly forty minutes shorter than the average westbound flight (travelling against the prevailing winds). TenOfAllTrades(talk) 01:49, 1 August 2007 (UTC)
 * Skittle: Lomn was correct in that the plane is moving 500 mph in respect to the air and not to the ground. The 100 mph air would be in respect to the ground, as well as the 600 mph being in respect to the ground. And thanks everyone for helping me clear it up. As a side question though, say you arrive faster than expected due to tailwind, you can use that to directly calculate average tailwind speed, correct? It would be distance divided by time saved equals average tailwind speed, and not something like distance divided by time multiplied by some drag coefficient, right? --Wirbelwind ヴィルヴェルヴィント (talk) 03:22, 1 August 2007 (UTC)


 * Specifically, what you have here is an object moving through a fluid (air counts) when the fluid is moving. As a pilot, they teach you about things like "airspeed" (the airplane's speed relative to the air), "wind speed" (the air's speed, relative to the ground) and "ground speed" (the airplane's speed, relative to the ground.)  It turns out that these things do actually just add-up, the way you'd expect.


 * Imagine a checker board. You move your piece 5 spaces forward ("500 miles North.")  In that same amount of time, the wind blows your piece 2 squares over ("200 miles East.")  A quick bit of trig will tell you how far you moved, altogether.  You don't even need the trig to know that, had the wind blown you 2 more squares North you'd be "700 miles North" from start or, if it were a headwind, you'd be only "300 miles North."


 * All of the inefficiencies in aerodynamics that have been bugging you since grade school happen before the airplane's original airspeed are calculated. That is, maybe the propeller is turning to push 525MPH of air backwards but, because of drag & whatnot, the airplane is only getting an airspeed of 500MPH.  So, while there is loss like your intuition suspects, the part about the airplane going 500MPH through the air still holds.


 * ...In the idealized problem, that is. We can do similar math with real airplanes, though, and it's pretty straightfwd.  We ignore propeller/jet slippage and just deal with "true airspeed" (aircraft speed relative to the air.)


 * Hope that helps! Oliepedia 05:29, 1 August 2007 (UTC)


 * Yep! Thanks! --Wirbelwind ヴィルヴェルヴィント (talk) 20:56, 1 August 2007 (UTC)

Back Crack
What happens when you crack your back? Why does it feel good? Is it healthy or dangerous? —The preceding unsigned comment was added by 151.28.233.145 (talk • contribs) 21:24, 31 July 2007  (UTC)


 * See Medical disclaimer. - hydnjo talk 22:52, 31 July 2007 (UTC)


 * And see Cracking joints. --Anon, July 31, 2007, 22:58 (UTC).

Brushing teeth before breakfast
Hi

I've been told that it has been "clinically proven" that brushing your teeth before you have breakfast is better than afterwards. Do you think this is true or false?

Cheers

Aaadddaaammm 22:44, 31 July 2007 (UTC)


 * depends on who's hype you believe. In theory, some toothpastes might form a 'protective shield' that would protect you from evil breakfast germs. On the other hand, toothpaste has been proven to be almost entirely bullshit, and advertisements are always bullshit. Personally, I'd say to brush your teeth after breakfast and after dinner --L onging.... 22:46, 31 July 2007 (UTC)


 * Funny, "toothpaste is bullshit" appears no where in our toothpaste article. Though surprisingly there are no citations in the article discussing the purported health benefits.  Dragons flight 22:55, 31 July 2007 (UTC)


 * Well, it isn't an active ingredient... --L onging.... 01:50, 1 August 2007 (UTC)


 * While many advertisements including toothpaste ones have a lot of bullshit, a claim made in an advertisement that it's been clinally shown that brushing before breakfast is better then after would probably mean there is at least one study that shows this in most developed countries (don't know about the US). It won't necessarily mean that there's been no studies showing the opposite although likely if most studies show that brushing after is better then before and you claim that it's been clinally shown before is better then after you'd be held up for deceptive advertising Nil Einne 12:52, 1 August 2007 (UTC)


 * See here.


 * It's not actually bullshit though. Plaque that's 24+ hours old becomes damaging to your teeth. If you can get it away without using toothpaste, be my guest. But I'm going to continue using a small amount when I brush. --Wirbelwind ヴィルヴェルヴィント (talk) 03:12, 1 August 2007 (UTC)


 * Or we could assume that no toothpaste is used at all... In theory, brushing before you eat breakfast would accomplish brushing away any large(relative to bacteria) bacterial colonies that might have popped up overnight.  Brushing after would brush away food particles that might lead to bacteria growth until you brush again.  Also, brushing after would remove those previously mentioned colonies as well as the food.  So let's say X = the time you would have brushed had you brushed before breakfast and Y = the time you would brush after finishing breakfast.  Notwithstanding technique or other such variables, it seems that as long as the time between X and Y isn't significant, then brushing after breakfast should accomplish the same thing brushing before would have and more.  However, add an antibacterial mouthwash and toothpaste to the party and you'll be cookin' with fire.Mrdeath5493 06:21, 1 August 2007 (UTC)


 * But there is the added problem that, apparently, brushing your teeth within half an hour of eating can damage the teeth (in the long term, if done frequently) because the enamel is more fragile straight after eating due to the mouth chemistry (pH if I recall) altering. So brushing before eating removes the plaque, so there is nothing for the sugar you eat to stick to, without removing any enamel. It doesn't remove food particles from the meal to come, but then I personally find that makes me retch! Horses for courses... Skittle 20:51, 1 August 2007 (UTC)