Wikipedia:Reference desk/Archives/Science/2007 January 30 to 31

January 30

DNA degradation

Hi

I'm trying to find out whether nuclear DNA or mitochondrial DNA degrades faster after death. I'm talking about forensic/fossil kind of situations. Does anyone have any tips/references/ideas?

Thanks for your help!

Aaadddaaammm 01:53, 30 January 2007 (UTC)

I think if you were after a reliable answer you'd have to spend a few hours hunting down papers on PubMed--inks^T 02:18, 30 January 2007 (UTC)

For a number of reasons, the mitochondrial DNA is more likely to degrade faster. The nucleoplasm is large, neutral, and contained within a double membrane, which is for the most part shrouded in layers of endoplasmic reticulum. The mitochondrial DNA, however, is in close proximity to stuff in more reactive oxidative states. Also, there is a lot of DNA in the nucleus, and a good deal of it in heterochromatin, wrapped up with histones and the like, which make it less reactive. The mitochondrial DNA is tiny and not as well protected. ^tucker/_rekcut 02:25, 30 January 2007 (UTC)

I'm not sure which degrades faster, however in forensic/fossil situations, mitochondrial DNA is more easily used for population level analysis, since there are more copies of it per cell than nuclear DNA. --Cody.Pope 09:27, 30 January 2007 (UTC)

• I think tucker's explanation is correct when it comes to the speed. Cody makes a good point, though. If there is more copies of mitochondrial DNA, there may be a question of which material is fully degraded first. - Mgm|^(talk) 10:06, 30 January 2007 (UTC)

Reduced Fat cheese melting point

I've noticed that reduced fat cheese melts much differently than normal cheese. A slice doesn't really melt, but rather it turns into leathery wrinkled chewy "cheese jerky" (especially when microwaved).The ingredients are virtually identical to normal cheese: Milk, rennet, salt. What's going on? --72.202.150.92 05:57, 30 January 2007 (UTC)

Fats tend to add the property of fluidity (for example, cholesterol in the cell membrane). With reduced fat, presumably there is less fluidity. Hopefully someone will come after me and give some biochemical details… − Twas Now ( talk • contribs • e-mail ) 06:21, 30 January 2007 (UTC)

Nuts

what nuts have embryos? —Preceding unsigned comment added by 58.168.42.153 (talk • contribs)

No nuts have embryos. Please see the nut (fruit) and embryo article if this is a serious question. [Mαc Δαvιs] X (How's my driving?) ❖ 07:15, 30 January 2007 (UTC)

Gallnuts are not true nuts, but they do contain larvae.--Shantavira 09:31, 30 January 2007 (UTC)

I don't understand Mac Davis's response in the context of the question. It seems to me that the Nut (fruit) article essentially claims that all true nuts contain embryos. Or am I misunderstanding the lede to that article?

Atlant 12:54, 30 January 2007 (UTC)

Yeah, Doesn't a nut contain a embryonic plant? ike9898 17:07, 30 January 2007 (UTC)

THank you for correcting me, I answered incorrectly, and will remember my error. All nuts are seeds and therefore have embryos. How early in development can we say a seed contains an embryo? [Mαc Δαvιs] X (How's my driving?) ❖ 19:39, 30 January 2007 (UTC)

• A nut is a seed, but not all seeds are nuts (from nut (fruit)).
• A seed plant embryo is part of a seed, consisting of precursor tissues for the leaves, stem (see hypocotyl), and root (see radicle), as well as one or more cotyledons (from embryo).

− Twas Now ( talk • contribs • e-mail ) 19:46, 30 January 2007 (UTC)

I thought he meant the testicles. ► Adriaan90 ( Talk ♥ Contribs ) ♪♫ 14:29, 3 February 2007 (UTC)

Protein synthesis

describe the process of protein synthesis in animal cell. —Preceding unsigned comment added by 212.88.98.165 (talk • contribs)

It would be more likely for someone to answer, if you made an effort to compose a question, and not just quickly copy-paste something from your homework. You can find a lot of information in our article Protein biosynthesis, and if something remains unclear, you can still return here and ask more specific questions. --V. Szabolcs 09:31, 30 January 2007 (UTC)

• You probably wouldn't have been asked this question if it wasn't in your textbook. I suggest you read that. - Mgm|^(talk) 10:03, 30 January 2007 (UTC)

The doctors say my friend suffers from electric discharge

Hello people from this fantastic site. First of all let me tell you that I have solved a lot of problems reading different articles on this site and want to thank you for all the information and time put in here.

I wanted to discuss something for which I cannot find an answer.

The doctors say my friend suffers from electric discharge. Let me explain what he feels often. All of a sudden he feels very tired, he cannot stand on his feet and his heart beats faster. His pressure usually goes very high and later it comes back to normal. Sometimes it even goes low and then back to normal.

Sometime back his potassium level had gone down and also suffered from diarrhoea for a long time.

Let me explain his work habits. He has very stressful days and he is on the computer for long hours, has 8 monitors and 2 CPU's which are on, almost 18 hours a day. While he goes out to work the computers are left on and he also sleeps in the same room. He eats too very very fast and just swallows the food.

I think I have given enough explaination. I was wondering if there is any connection with his lifestyle or if you'll you understand where his problem lies. Please do help me. Thanks in advance and hope to receive a reply. user: StellamirettoStellamiretto 09:39, 30 January 2007 (UTC)

Just a note: While someone may be able to explain electric discharge in some detail, we can't offer medical advice. − Twas Now ( talk • contribs • e-mail ) 10:29, 30 January 2007 (UTC)

Maybe your friend needs a thorough checkup and some lifesytle advice from a doctor/--Light current 11:55, 30 January 2007 (UTC)

I would encourage you, if your interest is to find out more about your friend's condition, to find out the medical name for his illness. Electric discharge is not a term that has any real pathological meaning to an allopathic (or, I suspect, osteopathic) doctor, as far as I know. This term may have resulted from an analogy or translation error. You may find information browsing the following, but don't jump to any conclusions: hypokalemia, cushing's syndrome, panic disorder, ozone. ^tucker/_rekcut 15:52, 30 January 2007 (UTC)

How many computers is irrelevant to his medical condition. How quickly he eats, also, probably doesn't have to do with it. [Mαc Δαvιs] X (How's my driving?) ❖ 18:59, 30 January 2007 (UTC)

You don't think that since he "just swallows the food" he will digest it poorly or get as much nutrients from it? − Twas Now ( talk • contribs • e-mail ) 19:50, 30 January 2007 (UTC)

I think it unlikely that he does bite off a chunk of food and swallow without chewing. Wouldn't he choke? I think that's an exageration on the part of the OP. --Seans Potato Business 23:48, 31 January 2007 (UTC)

Does your friend take any Antidepressants eg. Prozac, or Benzodiazepines eg. Valium, or does any illegal drugs? The reason I am asking this is because there is scientific evidence that these type of drugs increase or decrease the neuronal firings, which is involved throuhout the body. I mean this neuronal firings occur in the brain, but also expands via the spinal chord throughout the body. You might also be interested in the articles: Movement Disorders, Epillepsy and other neuroscience articles. Interesting question nonetheless, I will give you that. --Parker007 04:47, 31 January 2007 (UTC)

Swallowing the food lowers the nutriants that you recive from food. its also quite harmful it can get stuck and choke you. anyways it takes longer for the acids to digest the food so nutrients are cut off. it might also cause loose bowl movements, and might contribute a bit to his condition of feeling weak and everthing from not getting the nutrints from the food eaten. might be worth checking but im not giving you medical advice just simple run down on how the digestive system works with food. Maverick423 22:59, 31 January 2007 (UTC)

test for pesticides

can the lassaignes test be used for the detection of nitrogeneous pesticides in fruits? wont the nitrogen already present in fruits give a positive test, even if it has not been subjected to nitrogenous pesticides?

59.180.122.192 09:55, 30 January 2007 (UTC)

please help.

Scientific pronunciation dictionary

Where can I find an online dictionary for the pronunciation of the latin words used in taxonomy? Meanings too would be helpful. —LestatdeLioncourt 13:13, 30 January 2007 (UTC)

I did a Google search for "latin pronunciation" and found a number of sites. This one looked specific to your needs. As for meanings I imagine any Latin dictionary will be reasonably useful. --140.247.249.189 18:18, 30 January 2007 (UTC)

Pesky Air Bubbles

Is there an easy way to prevent air bubbles when placing a coverslip on a microscope slide. I have tried numerous techniques, none with satisfactory results. I tried tilting the coverslip, but this causes a "Tidal wave" effect since my samples usually aren't fixed to the slide. I tried slowly lowering the coverslip, but I can't seem to lower it slowly enough to prevent the bubbles. Does anyone know a better way? Mikmd

Do you have too much liquid on the slide?Particularly with low-viscosity solutions (stuff that's mostly water, rather than a glycerol-based mountant) there is a definite tendency for sample and mountant to get pushed out to the edge of the coverslip. (Your tidal wave effect.)

Depending on your application, you might try using less liquid, soaking off some of the excess liquid with a Kimwipe, using a larger coverslip, just putting up with the bubbles, or – if all else fails, and this is by far the most difficult option – experiment with changing your mountant.

Are the bubbles actually causing a specific problem for your application, or are they just not 'pretty'? TenOfAllTrades(talk) 15:28, 30 January 2007 (UTC)

Double bump... I need to type faster) :It sounds like you are using to much liquid. For a wet mount, there should be very little water, perhaps somewhere between 50 and 100µl. Putting the slide down on the edge, so that the water sticks to one side, and then slowly decreasing the angle between the cover slip and the slide with prevent air bubbles from forming. There will be just enough water to form a layer between the slip and the slide, so a "tidal wave" is not an issue. ^tucker/_rekcut 15:31, 30 January 2007 (UTC)

One of the best tricks I found was placing the coverslip on the slide on an angle. Then slowly place the coverslip on the slide.

_\-->the backslash is your coverslip, de underscore your slide.

This causes what you call the tidal wave effect but only when you do it too quickly. You shouldn't push untill the coverslip is flat on the slide. You generally want to push from the side you don't want your samples to flow to. Last trick is not to oversaturate the slide with your mounting medium (less is more!).

When I was doing slides with braintissue (not fixed to the slide) we used a sticky gunk called histomount. Now I don't know what your mounting medium is so I'm not sure if this trick will work for you.PvT 15:36, 30 January 2007 (UTC)

I was told to hold a piece of paper close to the slide, which should then absorb whatever liquid you are using, making it flow past the sample:) Something like that:( Pushing down on the top of the slide might also help, but it could damage whatever you are studying:(Hidden secret 7 16:07, 30 January 2007 (UTC)

If you have a "vacuum pickup" (that may not be the generic term), it makes it much easier to handle the coverslip, allowing any of several techniques to work better.

Atlant 16:40, 30 January 2007 (UTC)

I did some looking, and if you were to take my suggestion, what you want is something like the "Excelta" "Pen-vac" tool. It looks like pen but has a suction cup on the business end. You press and release a button on the pen barrel and it pulls a vacuum on the suction cup, letting you lift small smooth objects (such as glass cover slips). See We have one sitting around our lab that was apparently handed out as a promotional item.

Atlant 15:48, 31 January 2007 (UTC)

Thanks for the tips. Ill try some of them out soon. Mikmd 20:21, 4 February 2007 (UTC)

Hot melt glue...?

Is all hot melt glue made out of the same material and if so or not where can I find the Material Safety Data Sheet? 71.100.10.48 16:10, 30 January 2007 (UTC)

The article Hot glue talks about a "common" material for the glue.If you want specifics though, you'd want to read the packaging on the specific glue- different kinds may be made of different stuff.Friday (talk) 16:14, 30 January 2007 (UTC)

The packaging just says: Non-toxic Conforms to ASTM D-4236-88. 71.100.10.48 16:47, 30 January 2007 (UTC)

Loss of efficiency...?

What kind of efficiency loss would be the result of using DC generators to provide power with battery, capacitor, Superconductor magnetic storage, etc. devices to maintain the necessary voltage and inverters to provide a steady frequency within a specified voltage range to maintain frequency quality on the grid? -- Barringa 16:26, 30 January 2007 (UTC)

You'd probably still use an alternator (AC generator) fed into a rectifier. Alternators are mechanically simpler than DC generators and usually have better overall efficiency. The key, as you've probably realized, is the storage medium; it must be cheap, have reasonable energy density, and have good energy recover efficiency. Power utilities have experimented with batteries, compressed air, and pumped-storage hydroelectricity among others, with superconductivity remaining on the horizon.

Atlant 16:45, 30 January 2007 (UTC)

AC allows easy stepup to high voltage, perhaps 345 kv or 765 kv to send the power long distances, where it can be stepped down succesively to 138 kv to go from substation to substation, then 34 kv or 12 kv to go along distribution lines. While DC can also be sent long distances at 500kv or higher, per High-voltage direct current and [1] and is useful for tieing together different power grids which are not synchronized, it would be difficult to insulate Electrical generator windings to that voltage. To get enough turns of conductor in to the generator stator and rotor for it to work efficiently, the insulation level is usually less than 20,000 volts. Then a generating unit transformer steps it up to the higher transmission voltage. It would be a challenge to connect enough cells in series to have say even a 20,000 volt battery much less a 500,000 volt battery, because of the large clearances required by high voltage. In a downtown area of a large city, or an industrial park where constant AC voltage without momentary interruptions is needed for computer operation or growing semiconductor crystals, there would be great merit in having onsite energy storage in the form or batteries, superconductive magnetic storage, flywheel motor generator, or any other form of storage which acts as an uninterruptible power system on a large scale. That way if the utility line tripped and reclosed due to lightning, the customer or downtown would not see a flicker. It would be very expensive per megawatt hour of energy capability and per megawatt of power capability to provide such storage. Downtowns of New York, Chicago and other cities have had starting in the 1930's low voltage AC network grids, where perhaps 20 different 12kv lines go through transformers with the low voltage secondaries interconnected. Since the primaries come from several different substation fed by several transmission lines, the secondary 120/208 volt grid may go many years without even a momentary interruption, much less a Power outage. When it goes dead, there are usually numerous burned up low voltage cables, making for a long restoration time as in the 2006 Queens blackout. These grids were replacements for DC grids from the beginnings of utility power, in which a power plant (which needed to be within about 1.5 miles of the load) sent in DC which was stored in giant batteries. The load could be maintained with DC power during short interruptions of the line or short shutdowns of the generator, and could store power off peak, to increase the power available for the peak load period.Today labs and large data processing centers are the places which pay the premium to have "polished power" provided by systems such as you describe. More commonly, a business will have 2 or more 12 kv or 34 kv lines supplying it, and when one goes dead, an automatic throwover device opens the feed from the dead line and closes the other one, after a selected delay of perhaps 5 to 30 seconds, which can seem like an eternity. Typically the Uninterruptible power supply is small and is located near the personal computer or network server or phone system, since most of the load can be spared for a few seconds (vacuum cleaners, air conditioners, lights, etc,) except for a few battery powered emergency lights. Hospitals go the route of having generators (perhaps 10 MW diesels) which come online in 5 seconds or so for operating rooms and critical care units. Edison 17:16, 30 January 2007 (UTC)

poker millionaires??

Is it really possible to become a millionaire playing poker (or at least make a good living) or is this a bit of a myth in that gamblers tend to ignore massive losses incurred and remember their spectacular wins. Is it possible to learn a good strategy to constantly win or use a supercomputer etc for no limit texas hold 'em in the same way that you can card count in blackjack?

Yes, it is possible to become a millionaire playing poker; it is not easy, and there are very few players who accomplish this.(The top prizes for some major tournaments like the World Series of Poker and the Professional Poker Tour can reach more than a million dollars; bear in mind that the buy-in for competitors in these tournaments can be many thousands of dollars per player.)

No, you can't play 'by computer' to win at games like Texas Hold'Em.Unlike blackjack, poker depends very heavily on the behaviour of other players.I have heard it said that there are three stages to learning to play poker.The first is learning to play your own cards: understanding the value of your hands, how betting and blinds work, etc.The second is learning to play your opponents' cards: figuring out from the community cards on the table and your opponents' bets what hands they are likely to hold.The final step – and the one perhaps most important to professionals – is learning how to play your opponents.The cards can become nearly irrelevant if you can successfully manipulate other players' expectations and perceptions through clever betting.It's this last step that is difficult to 'teach' to a computer.TenOfAllTrades(talk) 17:07, 30 January 2007 (UTC)

There is no theoretical barrier to teaching a computer to react to and manipulate other players.A variety of poker playing computer programs already exist that can consistently beat the average player, but because they tend to be predictable in the long run, good players are still able to detect and exploit patterns that give them an advantage.It is a very complex task, but I don't think there is any reason a computer program couldn't be written to consistently make money on online poker.Dragons flight 17:29, 30 January 2007 (UTC)

Newton's cat

I once heard Isaac Newton invented the cat door/cat flap/kitty door. Can anyone confirm that?

Certainly plenty of websites [2] confirm this, although I can't find any truely definitive sources. If he did invent the door, it was more likely originally intended for his dog, Diamond, who famously set fire to all his work. Laïka 17:40, 30 January 2007 (UTC)

Every one has heard that version of the story which compromises the rather apocryphal little dog 'Diamond'; while it is supposed to exhibit so beautiful a trait of the imperturbability of his master. Humphrey tells us that he 'kept neither dog nor cat in his chamber.' Powell, Baden (1856). "Sir Isaac Newton". Edinburgh Review. 103: 499–534.

He kept neither Dog nor Cat in his Chamber... Keynes Ms. 135

—eric 18:38, 30 January 2007 (UTC)

Looking through his doorway we might have seen a small study...a desk littered with papers and lighted by a sputtering candle; a little dog with a diamond shaped mark near his tail, disporting himself in dangerous promimity to both candle and papers... Heyl, Paul R. (1928). "Newton as an Experimental Philosopher". Sir Isaac Newton, 1727-1927: A Bicentenary Evaluation of His Work. p. 105.

—eric 19:06, 30 January 2007 (UTC)

Newton's cat is a wimp. Schroedinger's don't need no stinkin' door. It can just tunnel out. Clarityfiend 05:34, 31 January 2007 (UTC)

I really want to try that experiment! (I hate cats). | AndonicO ^{Talk · Sign Here} 13:12, 31 January 2007 (UTC)

Sous-vide

Here's a "PERFECT STEAK RECIPE" that:

1. uses sous-vide to cook the inside of a steak in a warm water bath
2. then brown the steak's outside in a skillet to give the meat a brownish coat (see Maillard reaction).

Can I make a lot of individually wrapped boiled steaks, freeze them for storage. And then defrost them with a microwave oven for browning each time I want to have a steak? Is it safe? I guess an ordinary refrigerator may not achieve required flash freezing. You may need to use a large refridgerator with a large container of salty water to freeze the meat very quickly. The possibility of botulinum poisoning cannot be ignored. -- Toytoy 18:34, 30 January 2007 (UTC)

It states in the sous-vide article that there is a risk of poisoning by botulinum toxin, one of the most deadly toxins in the world. − Twas Now ( talk • contribs • e-mail ) 19:56, 30 January 2007 (UTC)

Boiled steak?? Come on, everyone knows perfect steak is done rare ;). The sous-vide article describes a process that I would not describe as boiling. Personaly I don't think there is a high risk of botulinum if you boil a steak and then re fry it at a later date, otherwise no one would ever eat left overs. I suppose the important thing is that when you fry it you have to make sure it is heated well all the way through, so probably wait until it is well defrosted before doing it and don't just sear the outsides. Vespine 22:02, 30 January 2007 (UTC)

It's not refrigeration that creates the risk of botulism, it is the boiling in an airtight plastic bag. Clostridium botulinum, the bacteria which causes botulism, thrives in low-oxygen environments (such as would be found in an airtight container). − Twas Now ( talk • contribs • e-mail ) 03:31, 31 January 2007 (UTC)

Recall that there is no scientific basis for abiogenesis - that is, if there is no botulism in the meat to begin with, then no amount of boiling (in airtight bag or otherwise) will create botulism.There is not a good way to know with certainty whether there was infectious bacteria to start with; but, the high temperatures of boiling should be sufficient to deactivate or kill them.Just be sure to keep the meat in the boiling water for long enough to heat the meat. Nimur 07:23, 2 February 2007 (UTC)

The water is not boiled, but kept at around 60°C (140°F). − Twas Now ( talk • contribs • e-mail ) 07:48, 2 February 2007 (UTC)

Magnetic materials

Hello! Could someone tell me a few applications for magnetic materials?--Anonymous

I'll give you one - loudspeakers - how and why can be found in magnet under the section magnet#Common uses for magnets and electromagnets - ignore the electromagetic uses - and not suprisingly the major use for magnetic materials is as magnets!87.102.13.207 20:18, 30 January 2007 (UTC)

Depleted Uranium Disposal

Does anyone have an idea of the best way to dispose of depleted uranium(without putting it into weapons)? DebateKid 20:01, 30 January 2007 (UTC)

Well it isn't an extremely dangerous material. It has extremely low radioactivity and is more dangerous as a heavy metal (and potentially a source of radon -- you wouldn't want to build a house over a mound of it, I imagine) than it is as a radioactive element (though this depends on the form you are talking about disposing -- if you are talking about hexafluoride gas, that has its own difficulties from a chemical point of view). In any case, this page has a nice discussions of the precautions usually taken. If you treat it as any old Low Level Waste material, that means that you probably want to bury it in the ground for some long length of time. Because the amount of radioactivity is low, the length of time it will be radioactive will be quite long, though even if it escaped for some reason it would only have a small long-term statistical effect on any surrounding populations. --24.147.86.187 22:39, 30 January 2007 (UTC)

Why would you want to dispose of it? is it not a useful material? DU I imagine it could be used for many of the things that lead is used for.--Light current 22:49, 30 January 2007 (UTC)

Indeed.For example, the first Boeing 747 had several hundred pounds of it formed into the engine nacelles, because the designers discovered at the very last minute that they needed a concentrated bit of mass just there to damp out certain wing vibrations. —Steve Summit (talk) 01:54, 31 January 2007 (UTC)

It is useful though I could imagine not needing ALL of it that we have at any given time. The US alone produced 30,000 tons of the stuff over the course of the Cold War -- way more than we will ever need even for munitions. --Fastfission 13:16, 31 January 2007 (UTC)

Our article lists several uses like sailboat ballast and "dental porcelain"? I think I would pass on that myself. Rmhermen 05:27, 31 January 2007 (UTC)

What would the slogan be?Just like lead...but radioactive.Mmmmm.:) --18.214.1.125 01:29, 31 January 2007 (UTC)

Uranium 238 appears to be less radioactive than certain isotopes of lead. U238 half life is 4.5 billion years. Thats longer than the age of the universe earth! 8~)--Light current 01:35, 31 January 2007 (UTC)

so basically, I think you could eat it with negligible damage from a radiological point of view.--Light current 02:28, 31 January 2007 (UTC)

Someone's going to kick off over that comment. I just know it. :) --Kurt Shaped Box 02:30, 31 January 2007 (UTC)

They can argue with this then! [3]--Light current 02:34, 31 January 2007 (UTC)

Yes in terms of radiation poisoning DU is no bigger risk than any other commonly encountered substances and you will die far sooner from heavy metal poisoning than radiation poisoning. --antilived^{T | C | G} 06:33, 31 January 2007 (UTC)

In terms of radiation poisoning, U238 is practically harmless, yes. Its decay products are more radioactive though. And in any case there is an additional radiological danger than just radiation poisoning, such as if amounts of it get into your bone marrow or your lungs (I don't know if U238 or its decay products do this, but it is a common hazard with low-level radioactive isotopes). Then they just sit there and radiate for a decade and give you cancer. I'm not saying DU is particularly dangerous in this regard -- I'm not sure that it is, and I think most of the anti-DU literature is scientifically unsound -- but I'm just pointing out that you can't dismiss the danger of something just by showing that one of the isotopes is only weakly radioactive, and even then you have to take into account whether the danger is posed by radiation sickness or by long-term cancer incidence. --Fastfission 13:16, 31 January 2007 (UTC)

If you had some and were worried, you could always put in a polythene bag. The alpha emission will be completely stopped!--Light current 13:41, 31 January 2007 (UTC)

DU is very effective at shileding you from radiation. Soi there should be some applications there! Then of course you could make guitar frets out of it (Heavy metal bands only 8-))--Light current 16:32, 31 January 2007 (UTC)

How about a baseball bat with a small piece of DU inserted into the tip? :) --Kurt Shaped Box 22:59, 31 January 2007 (UTC)

yes its moment of inertia would be increased!--Light current 23:03, 31 January 2007 (UTC)

I'm surprised that no-one has mentioned Fast breeder reactors; these turn U-238, the main isotope of DU, into Plutonium-239; an unbelievably power nuclear power station fuel. The only downside is that only a handful have ever been built: the French Superphénix and Scottish Dounreay reactors are the most famous, but the Soviet Union was on the way to 6 at the point of break up. Also, at the moment, enriching normal uranium is cheaper than making plutonium, but if U-235 reserves run down, you can expect to see a large takeup of FBR technology. Laïka 20:34, 1 February 2007 (UTC)

Appendicitis and diet

Is there any relationship?--Light current 22:47, 30 January 2007 (UTC)

My nan used to tell me never to eat tomato seeds as they could get stuck in my appendix and cause appendicitis. I don't know if that's true or not (to be honest, it's something I haven't thought about for a long time) - but come to mention it, does anyone know? --Kurt Shaped Box 22:51, 30 January 2007 (UTC)

Seeds and nut fragments can indeed become stuck in outpouchings of the colon and intestines (called diverticuli) and cause inflammation and possibly infection. The appendix, though, has a pretty wide mouth, so it is probably less likely for anything to get stuck in there for too long. From what I've read, the biggest predictor of appendicitis is posture during bowel movements. In societies where one squats to defecate, appendicitis is rare, because the pressure of the right thigh against the abdomen may squeeze out the contents of the appendix. However, since the appendix has variable placement, this is only a predictor. ^tucker/_rekcut 23:04, 30 January 2007 (UTC)

How about toothbrush bristles and chewing gum? I was warned about those as a kid too... :) --Kurt Shaped Box 01:15, 31 January 2007 (UTC)

I'm pretty sure they are old wives tales, my mum used to tell me if you ate apple seeds a tree might grow in your stomach... WHY??? I have no idea, but I can't wait to fck with my kids heads by telling them crazy crap! when I have some:).. Vespine 03:07, 31 January 2007 (UTC)

Actually, it was a serious Q 8-|--Light current 03:11, 31 January 2007 (UTC)

Despite popular belief, you will just pass the chewing gum out "the other end", rather than it doing any damage to your internal organs. People believe chewing gum may have this effect becasue it is sticky & could potentially adhere to your intestinal walls, but in all reality, your stomach acids & functions would easily break down the make up of chewing gum. However, I myself would not swallow it... :) As for toothbrush bristles, it is possible for them to enter through opeinings inside you. However, this is very very very rare & would take a miracle for it to do any real damage. Swallowing stuff like this runs the same risk (or a smaller risk) as if you ate some other small object, such as a marble or key - it passes through your body without harm... Hope that helps a little bit..? Spawn Man 04:03, 31 January 2007 (UTC)

One's diet I do not believe has any effect on appendicitis frequency. The human digestive system evolved to take in seeds and such from eating fruit. [Mαc Δαvιs] X (How's my driving?) ❖ 07:40, 31 January 2007 (UTC)

A relative had recurrent bouts of appendicitis over several decades, before it became acute and the thing leaked into the abdomen and surgery finally removed it. Each case of the painful intermittent appendicitis which resolved without surgery until the final one followed eating a large high fiber meal like chili or salad, and the agonizing lower right abdomen pain would follow a few hours later, but was better in a day or so. Edison 16:35, 31 January 2007 (UTC)

Ethnomedical treatment for Persimmon

In the persimmon article, it says that persimmons are used to treat constipation, but persimmons are astringent, so they should be used to treat diarrhea. Can anyone tell me if persimmons are used to treat constipation or diarrhea? bibliomaniac15 23:40, 30 January 2007 (UTC)

Wrist damage

Just wondered if too muck jackin can damage your wrist!

No - penis usually breaks first.87.102.2.51 00:43, 31 January 2007 (UTC)

Though this sobering tale should give you cause to consider moderation

Moderation mate is CRITICAL

Maybe you haven't wanked yourself as much as I have.

If you wank 5 or more times a day , everyday, for at least 5 years, you will know what i'm talking about.

You can get serious repetitive strain injuries on both wrist, AND testicle disorders, AND cock shaft problems from excessive friction, AND bacterial infections from not being able to wash your hands before you NEED a wank. if you wank as much as I do, you can get seriously addicted, to the point where you cannot walk if you do not spill your juice. AND your wrists are fucked and you cant walk, (like ive been), you are totally FUCKED

Crack one off once or twice a day and you should be on the safe side of injuring yourself.

from http://www.steadyhealth.com/Masterbation_t63170.html 87.102.2.51 00:54, 31 January 2007 (UTC)

Hmmm... Artificial vagina to the rescue, I guess. If lots of exercise, a few fist fights, enlisting in the army and imagining the Queen in a bikini don't do the trick. Anchoress 03:04, 31 January 2007 (UTC)

Usually it's the last one for me that gets me off! :) [Mαc Δαvιs] X (How's my driving?) ❖ 07:33, 31 January 2007 (UTC)

Not a thong? Excuse me, I'm going to be very ill. Clarityfiend 01:27, 2 February 2007 (UTC)

My guess: I would suggest you to do some stretching and strengthening exercises for elbows and wrists. Also, be careful while masturbating, don't do it too strong or some problems may occur. I know a guy who developed epicondilitis which he thought the main factor was masturbation. --Taraborn 19:38, 3 February 2007 (UTC)

January 31

Highest Temperature Possible?

Hello. I was reading an article on the temperature of 0*K, or absolute zero. I was thinking, if the lowest possible temperature is achieved when the atoms of the material stop moving completely, then wouldn't the highest temperature possible be achieved when the atoms are moving at (or close to) the speed of light? I mean, when an atom is moving at the speed of light, it can't move faster, so it can't raise in temperature, can it?65.28.13.120 00:54, 31 January 2007 (UTC)65.28.13.120Wild Irishman

According to the theories E=mc²#Background - the energy keeps increasing as the speed approaches the 'speed of light' - but a thing would have infinite energy at the speed of light - so there is no upper bound to the amount of energy a moving thing can have - effectively the mass is supposed to increase as the speed increases (see section 'relativistic mass' in a sub section of the section linked above- and things with more mass have more kinetic energy at a given speed.

So if an atom was at the speed of light it would have infinite energy..87.102.2.51 01:01, 31 January 2007 (UTC)

Yes, which is obviously impossible.  freshofftheufoΓΛĿЌ  05:01, 31 January 2007 (UTC)

Thermodynamic temperature has some interesting info about record high temps. Interestingly, the highest possible temperature is higher than infinity, which is—even more interestingly—negative. DMacks 05:07, 31 January 2007 (UTC)

There's a certain sense in which the highest temperature possible is −0. See negative temperature for details. However you can't actually get matter that hot. But there are certain thermodynamic systems that you can get that hot. --Trovatore 05:11, 31 January 2007 (UTC)

I think this is semantic silliness.Though thermodynamics defines negative temperature in this fashion, with a sort of population-inversion phenomenon equaling "negative" temperature, two points come up: First, this is an impossible situation to construct in a real, physical world; and second, such a definition of temperature is so far from the conventional meaning that it should really have a different word - such as "energy state distribution." Nimur 07:33, 2 February 2007 (UTC)

You are confusing science with the real world:] The highest possible temperature would be in the centre of the hottest possible star:) Temperatures above this can't exist even if they are possible:)Hidden secret 7 20:38, 3 February 2007 (UTC)

Space combat with lasers...

Would I be right in thinking that ship-to-ship combat in space with lasers would be an incredibly brief affair? For all intents and purposes, a laser is an instant hit weapon - so, whichever ship managed to lock on to the other with a 360-degree rotation-capable, turret-mounted, computer-controlled laser first and concentrate the beam onto the same spot on the hull for a few seconds would emerge victorious, right? None of this dogfighting-in-space stuff like you see in the movies. I know that if combat in space became a regular thing, the design of ships would evolve to reflect this (thick armour plating, separately pressurised compartments, mirrored hulls, clouds of chaff launched to defract the laser, etc.) - but that would pretty much be the gist of it, right? Two ships firing at each other constantly, hitting 100% of the time, each hoping that the other one decompresses or is disabled first? --Kurt Shaped Box 01:46, 31 January 2007 (UTC)

Much easier than making a viable space-based laser would be coating objects to reflect large amounts of the energy.Extremely powerful lasers are often in the infrared range like hydrogen or deuterium fluoride lasers which is reflected quite well by copper, gold, or germanium (common mirror materials in CO2 lasers, which operate in the far-infrared).Lasers have tons of problems.It would be extremely difficult to focus enough energy onto a small enough spot at great distances, or be able to track very quickly and accurately.Hardened missiles might be a viable weapon, assuming we have space wars anytime soon.You're probably right thought, what this would be like if it worked well would probably be pretty dull, which is why Star Wars, Star Trek, et. al. spice it up with cool-looking weapons.Atropos235 02:11, 31 January 2007 (UTC)

HEY! Maybe that's why those UFOs in old 'saucer' movies spin? So that an enemy targeting the ship with a laser can't hit "the same spot" for any amount of time, because "the same spot" is rotating around the craft.. It's a laser weapon countermeasure! Hmmm, that's interesting!:) Vespine 03:03, 31 January 2007 (UTC)

Even if the technology did exist to aim huge amounts of energy accurately over large distances, there's going to be a range in which it causes damage, and aiming at any target outside that range cause progressively less and less damage relative to the distance. In the middle there's a range where it causes a little damage (uncomfortably hot/minor radiation damage), and since there's no reason to believe that ships are going to be popping into existance a few meters away and you're not suicidal so you're not going to rush in when you don't have to, that's the range where most of the action would probably have out, making incredibly slow and boring fighting sequences.  freshofftheufoΓΛĿЌ  04:59, 31 January 2007 (UTC)

Yes, it would be a range limit, but it would surely not be a few hundred meters like in the movies. Even atmospheric air combat is fought now most of the time beyond visual range, so it's funny a Star Destroyer can't fire at a spaceship until someone has visually identified the target (pointing to the window: "there they are!") --V. Szabolcs 00:40, 1 February 2007 (UTC)

When in the history of warfare has there even been a weapon that couldn't be countered defensively? Even nukes don't make a dent in bedrock. Vranak

Bedrock isn't really a viable defense tactic for most major cities in the world.  freshofftheufoΓΛĿЌ  07:00, 31 January 2007 (UTC)

Aren't sewers sometimes below bedrock? ;-) | AndonicO ^{Talk · Sign Here} 13:21, 31 January 2007 (UTC)

Really doesn't matter. By "no defense," in the case of nuclear weapons, it means "there is no way to prevent someone from detonating a nuclear weapon over your city." (Some would dispute this, of course, and that's part of the entire debate about missile defense.) --140.247.248.95 17:41, 1 February 2007 (UTC)

A laser might have an energy storage device (capacitor, for instance) which takes some time to charge to full energy, so that it could do damage in a short pulse, without having to lock on for an extended time. Directed-energy weapon says "Laser weapons usually generate brief high-energy pulses. A million joules delivered as a laser pulse is roughly the same energy as 200 g of high explosive, and has the same basic effect on a target." I would rather destroy an opponent (perhaps defined as "burning a hole in their hull at one spot") with a blast than have to barbecue them over a few seconds, during which they would change course in evasive maneuvers and fire back at me, so this makes sense. Several weapon systems could charge off the main electrical bus, without having to have a separate nuclear reactor or whatever at each weapon station. A ship might have, say, two 1000 MW reactors, and several 500 MW power cables, like an electric utility. A weapon could draw 500 MW for say 10 seconds, and store 5000 MJ, to be supplied in a laser pulse which is done before the opponent can respond or maneuver. Per the above equivalence, this would be like detonating 1000 kg of high explosive, and should make quite an impression on a space ship made similarly to our present technology. If half the ship's power were directed to a single weapon, it would take 1.25 seconds to deliver the same energy, allowing evasive maneuver which would spread the energy over a larger portion of the hull. If the attacker had 4 weapons, each could be charged to the same 5000 MJ before the attack, allowing 20,000 MJ to be directed to one target area on the other ship's hull, or allowing it to be penetrated in numerous smaller explosions. Laser pulses would travel at the speed of light. I expect that particle beams would go slower. Bullets or artillery shells would travel slower as well, and the tartget would likely not be there when they arrived, unless it was an attack on an unsuspecting and defenceless target. Plus, the bullets or shells would orbit until they hit something or reentered the atmosphere. A RPG or equivalent would be deadly against pretty beefy space ships as well, but a radar proximity fuse would be needed to detonate it at closest approach. A guided munition like antiaircraft rockets would be pretty devastating if it could hit or get near a target. Edison 17:04, 31 January 2007 (UTC)

I took the liberty to fix your units. mJ is a millijoule (10^-3 J), not a megajoule (10⁶). — Kieff | Talk 22:18, 31 January 2007 (UTC)

That would have been a very low efficiency and fairly non-violent weapon, a bit like aiming a laser pointer at them. Oh, well, it would probably get their attention. Thanks. Edison 15:47, 1 February 2007 (UTC)

Space combat will have to be made clean cause any debris that flys out is a potental bullet. so lasers will have to be strong enough to burn a hole in the hull and not cause much debris from the explosion. in diff note. if we dont care about debris then i can think of better weapons like cluster missles that explode in the middle of a on comming fleet and lay waste to all enemys. however lots of debris will be released and possably even hit the person that fired the missle to begin with! There is development of a plasma sheild (saw that one on a show think it was future weapons on the discovery channel) however it requires a lot of energy to produce. if you are intrested in space weapons watch Wing Commander that one had more of a realistic approch to space weapons then most shows and movies. Babylon 5 is a great show for watching the weapons in action (however all the effects are added but it was a show that used more physics then anything) Star wars and Star Trek are more fantasy based. and for games well i can only suggest a old game called haegemonia it has 4 diffrent types of space weapons and it gives breif definitions of them and added information of the weapons when you upgrade them. Maverick423 22:04, 31 January 2007 (UTC)

I figure I'd point out Boeing's Air Borne Laser .Though it's not for space, its purpose is to burn a hole in a missile's outer "shell" - rendering it aerodynamically unstable and/or damaging its control electronics.The task of targeting a very fast moving missile is accomplished via powerful computers, multiple radar tracking schemes, and a lot of luck.Supposedly, early tests have been successful, though it is still a prototype. Nimur 07:41, 2 February 2007 (UTC)

Kittens

I got 2 2-month old kittens from my freind. they havent been spayed, neutered, and didnt get any shots yets. they both look the exact same. i cant realy tell them appart. she said one of them is male and the other is female. i checked them both out all around and niether of them seems to have a dick. how do i know which one is which?

hahaha! A kitten with a dick! I'm nearly 30 and I still find that funny.. I guess some people never grow up... Anyway, really, in public, you should refer to it as a penis:).... As for the answer, google kitten sex and I'm sure you'll find the answer, if you ignore all the kitten porn sites first:), I'm sure it's easier to explain with pictures then with words.. As for the kittens not having a visible penis, that's right, cat's penises are retractable, so you can't really tell just by the dick. haha. sorry, *cough*. hmmVespine 02:57, 31 January 2007 (UTC)

Vespine, that may have been a bit insensitive. He can call a schnoz whatever he wants. I mean a schlong! Dick? John? Jimmy? Cock? Penis? We could go fancy and say "phallus." Damn, we're smart now aren't we? [Mαc Δαvιs] X (How's my driving?) ❖ 07:36, 31 January 2007 (UTC)

As they are both now old enough to be neutered, take them to your vet who will perform the operation and tell you which is which. As with many animals, the cat's penis is withdrawn when not in use to prevent damage, so you will not normally be able to see it. However, the testes form a little bulge which you may be able to feel.--Shantavira 09:09, 31 January 2007 (UTC)

Once you find one which one is the girl, tie a pretty pink bow around it and then you'll always know. Give the boy kitten a baseball cap and some toy trucks. --24.147.86.187 13:20, 31 January 2007 (UTC)

How steriotypical!

Granted that some kittens are so small it's hard to tell, but look at the rear (butt) of the kitten. On females, you can see the anus and not much else (the vagina is not easily visible). On males, beneath the anus there's usually a lump where the [insert your penis euphemism here] is. howcheng{chat} 20:36, 31 January 2007 (UTC)

Sleep

I'm a highschooler with a packed academic schedule and a hell of a lot of homework that usually keeps me up to, say, 1, or 2 in the morning every night. I wake up fairly exhausted at 6:30, but I tend to do fine at school. When I get home at fourish in the afternoon, I've gotten in the habit of taking a one or two hour nap because if I don't, I tend to get bleary eyed and can't focus when reading anything, so I just waste time reading the same paragraph a hundred times. After a week of this, I'll usually catch up some on sleep over the weekend. The question, however is one prompted by my dad's getting angry at me for this "bad cycle." He says I should make an effort to stop napping so I can instead go to sleep two or so hours earlier and get the same amount of sleep but on a normal schedule. Apart from the fact that I probably wont go to sleep much earlier at all (even on the days with light homework and no naps, I get a second wind of sorts at around ten or eleven and am not tired - read unable to sleep - until at least 1:30 in the morning), is this really so much better of an idea? I feel that if I take an early afternoon nap, I'll be alert for the rest of the night (which is the case), whereas the extra sleep I'd get during the night would still probably leave me bleary eyed in the afternoon because it's still only 6 or so hours of sleep. It also seems to me that my dad's argument is similar to someone saying that three meals a day are more healthy than 5 simply because that's the "normal" cycle of eating. Is my dad's "normal" sleeping cycle of one 6 hour night actually any better for me than a four hour night and a two hour nap? Thanks, Sashafklein 04:01, 31 January 2007 (UTC)

As far as I know, it's contested. You'll hear people say things like "Leonardo Da Vinci napped 12 times a day", though that's (probably) not (quite) true. First of all, realize that shifting your 2-3 hour nap into the evening all of a sudden will not immediately show positive results. The most important thing is to keep a regular schedule, and changing your regular schedule will make it difficult to sleep well, at least until you become accustomed to the "new" schedule. Trying to "catch up" also isn't a good idea, because your body doesn't respond to weekly patterns of sleep, and you're basically assuring that your brain will have to shift schedules twice every week. I have horrible sleeping problems too, but I attribute most of them to the fact that I'm not strict enough about my sleeping patterns.  freshofftheufoΓΛĿЌ  04:39, 31 January 2007 (UTC)

The only reason I believe that you have a need to sleep after school is because you are introverted thus your energy is drained in any social settings.--Parker007 05:39, 2 February 2007 (UTC)

He may be physically exhausted in some way after school. Also, your mood may have to do with it. For me, my sleep depends almost entirely on my mood. When I went to high school, and came home, a lot of times I wanted to go to sleep but instead did my homework and really didn't want to talk to anybody. [Mαc Δαvιs] X (How's my driving?) ❖ 07:31, 31 January 2007 (UTC)

Check out Siesta#Biological need for naps, or at least the references provided therein. Clarityfiend 05:26, 31 January 2007 (UTC)

To mention my piece, I've done plenty of sleep research reading and I've found no long-term effects in humans of sleep deprivation. I know your problem well, and actually liked polyphasic sleep pretty well! However the problem is you have to form to society, who sleeps monophasically, and I have to comform to my dad, and follow his schedule, generally. I recommend you follow his schedule, just to make it easier for him. Keeping your dad happy can come in handy :) and also he can be pretty smart sometimes and know what he's talking about. [Mαc Δαvιs] X (How's my driving?) ❖ 07:29, 31 January 2007 (UTC)

Do your homework as soon as you get home, then sleep. You'll get used to it in about a week. | AndonicO ^{Talk · Sign Here} 13:27, 31 January 2007 (UTC)

As always, we cannot give medical advice. See your doctor if you feel unusually tired or nervous or agitated or depressed. But as a general observation, see Sleep deprivation, where some pretty horrible effects are listed. I have read of experiments where animals (and torture victime) died as a result of prolonged sleep deprivation, but can't readily find what I would call reliable sources. There is a blog [4] so take that as an unconfirmed effect and a more credible BBC story [5] in which experimental animals are said to have died from sleep deprivation. Falling asleep at the wheel and crashing a car from sleep deprivation also leaves someone dead.Interrogators like to claim that sleep deprivation is not torture and has no long term effects, because then they have a tool besides Waterboarding which is harder to prove was used than, say, The rack, beating, red hot pinchers applied to the genitals or even electric shocks, but which can leave the victim disoriented and less able to resist their demands. There was a gentleman whose brain developed an anomaly which did not allow hin to fall asleep, and after a long period of incresing zombification he died. But given he had an abnormality in the first place it is hard to be sure whether the sleep deptivation or the underlying problem killed him. See also Power nap. When I was in college I would nap from 3:30 to 4 pm and be refreshed enough to work another 7 hours, making one day into 2, and still being able to sleep from 11 pm until 7 am. At around 3:30 pm, my circadian biorhythm was such that I was drowsy, so a nap was the best use of my time. See [6].Thomas Edison was a famous napper, and would alternate what we would today call All-nighters with days having short naps. An afternoon nap when you are drowsy and unproductive anyway might make sense. People differ in their ability to take a power nap and awake refreshed; some seem to stay groggy for a long time after a nap. A long uninterrupted period of sleep at night may be needed to allow the necessary sleep cycles of deep sleep and REM sleep which the brain needs to do its maintenance, including storing the days short term memories into long term memory. You may have gotten into a vicious cycle of staying up late, getting too little nighttime sleep, having trouble getting up and staying alert in school, then taking a long afternoon nap (while it is light and there is noise in the house, interfering with the chances of REM sleep), then playing catchup. The long 2 hour afternoon nap might be replaced by a half hour nap and 1.5 hours of homework to good effect, with a correspondingly earlier bedtime. Coffee, booze or weed at various times of the day can interfere with sleep or alertness. Some people who say they stay up until 2 am doing homework did not work for very many concentrated hours on the homework earlier in the evening, since it was interspersed with distractions. I would try taking a half hour nap (use an alarm clock) after school, then attacking the homework before and after dinner, and before any watching TV, hanging out with friends, IMs, phone calls, recreational reaading, etc. Then go to bed at 11 pm and get up at 7 (or whenever is needed to get to school). You could also budget for some AM study time. A Fox news article [7] says that 6 to 7 hours of concentrated sleep may be as healthy as 8 hours. Take that as just what one source said. Too little sleep reduces the chances of being attentive and productive during the day, and caffeine is no substitute. Afternoon caffeine (coffee, tea, cola, even chocolate) may make sustained sleep difficult. Edison 17:54, 31 January 2007 (UTC)

If you don't already, you may consider working through your school break-time and lunch-time (may be able eat at the same time, depending on your teachers/arrangements at your school). Of course that probably wont do any good for you socially. --Seans Potato Business 00:06, 1 February 2007 (UTC)

Sister chromatids during meiosis

In all of the literature I have read, after non-sister chromatids cross over during Prophase I, they are still called sister chromatids. I was under the impression that sister chromatids are, by definition, identical copies of one another. After crossing over, this is not the case, since homologous pairs have swapped genetic information.

Now, until the end of Metaphase I, the homologous chromosomes are still loosely connected to each other, so perhaps the distinction is not clear until then. However, once Anaphase I is reached, the so-called "sister chromatids" are certainly distinct, non-identical entities.

Why are these still called sister chromatids, despite containing different genetic information? − Twas Now ( talk • contribs • e-mail ) 05:04, 31 January 2007 (UTC)

Perhaps I should reframe this question: Is there another name for these chromatids after crossing over? − Twas Now ( talk • contribs • e-mail ) 07:15, 31 January 2007 (UTC)

There are good animations with explainations on this website: [here ]

MRCA of humans and various animals

The most recent common ancestor says that Richard Dawkins gave 5-7 MYA as the time when the MRCA of humans/chimps/bonobos existed. What would be a reasonable estimate for the MRCA of humans and dolphins? Humans and squid? --Awesome 05:07, 31 January 2007 (UTC)

According to Richard Dawkins in The Ancestor's Tale, the Laurasiatheres (which contains dolphins) joined the Euarchontoglires (which contains humans) around 85 mya. The Protostomes (containing squids) joined the Deuterostome (containing humans) an estimated 590 mya, though Dawkins states there is a large margin of error on this second estimate. − Twas Now ( talk • contribs • e-mail ) 05:31, 31 January 2007 (UTC)

Refraction of light

Why does a light deviate from it's initial path when it changes the medium in which it is travelling.That too when it makes an angle with normal at the interface of the different media.(Ecclesiasticalparanoid)

Check out our article on refraction. − Twas Now ( talk • contribs • e-mail ) 07:11, 31 January 2007 (UTC)

Well, the simple answer is that the phase velocity of the EM field has to change when it propagates into a material with different complex permittivity and permeability in order to continue to satisfy the boundary conditions associated with Maxwell's equations (the refractive index and related reflection/transmission factors are themselves functions of permittivity and permeability).Put another way, the wave vector is changed when the field propagates through a region where the speed of light changes.If you want a more detailed physical explanation, you may need to invoke the relativistic explanation of Maxwell's equations (Kaluza-Klein theory).I don't think there is a quantum mechanical explanation of EM wave refraction since Maxwell's equations only work on a macro scale where quantum interactions can be ignored (indeed, permeability and permittivity are "averages" and only well-defined on a macro scale).Reading a bit about the plane wave solution to Maxwell's equations may be a little enlightening.Maybe a physicist could chime in and fill in some details.Wave mechanics are a fairly involved (and highly important) topic.See also: Snell's law, Fresnel equations. -- mattb @ 2007-01-31T16:05Z

The quantum-mechanical explanation you speak of is given by quantum electrodynamics.The light moves at different speeds in different materials and "chooses" the shortest path through a material that it can make at that material's light speed.Since this path must become longer as the speed decreases, the light will bend towards a greater distance of material.If you go by the QED interpretation (path integrals), this "choice" is actually a result of the light having a probability to travel along every possible path, but all the probabilities except for those along the shortest path cancelling out due to destructive interference.See the book QED (book) for a great explanation for a general audience. 75.138.84.159 04:25, 1 February 2007 (UTC)

Ah, I totally forgot about QED theory.Thanks! -- mattb @ 2007-02-01T05:28Z

Dinosaurs

Well, I'm interested in dinosaurs, and I've stumbled across a question that has been almost impossible to answer. Up until now, I've only been interested in flashy stuff, like battles, etc. But now, I've come to the most foreboding aspect of the study of dinosaurs: size. It's been almost impossible to find two sources that cite the same figures. For exmaple, weights of Brachiosaurus vary from 15 to 180 tons. The stats for smaller dinosaurs are more or less similar. I was wondering if anyone could give me a list of sizes for the larger sauropods. The article 'Dinosaur size' only gives you the smaller estimates. I'm not asking for anything to specific: just a basic idea, but detail would be appreciated. My thanks to anyone who answered this question.

I can't answer this question but i think i remember a Documentry on dinosaurs called "Walking with Dinosaurs" it has some pretty neat battles and it also gives us a pretty good decription of how tall your Average sauropod would be..I think its out on Dvd or something Hope this helps Catman503 14:21, 31 January 2007 (UTC)

That will be the BBC documentary series Walking with Dinosaurs, which used computer-generated imagery and animatronics to recreate the life of the Mesozoic era. Gandalf61 14:45, 31 January 2007 (UTC)

You may find Wikipedia:WikiProject Dinosaurs & Wikipedia talk:WikiProject Dinosaurs interesting. The guys there are experts, & I hang around there often. Dinosaur may also give you some answers. Hope that helps, as you can ask questions at the wikiproject, Spawn Man 21:49, 31 January 2007 (UTC)

azeotrope at different pressure for any system say(ethanol/water)?

any one who can give this answer send it on (e-mail removed)

It might be important if you can clarify - do you want real data - or thermodynamic models - or both?87.102.7.133 15:17, 31 January 2007 (UTC)

Sulfuric_acid#Uses

In section 'sulfur-iodine cycle' it states "Additionally, the sulfur-iodine cycle has a much lower maximum operating temperature compared to traditional electrolysis."

This makes no sense to me - can someone who understands what it is supposed to say please correct it. See also Talk:Sulfuric_acid#Uses. Thanks.87.102.7.133 14:50, 31 January 2007 (UTC)

It also states " With an efficiency of around 50% it is more attractive than electrolysis" - well doesn't electrolysis have a higher efficiency? I'd simply delete this - but want to check I'm not missing something obvious..87.102.7.133 14:53, 31 January 2007 (UTC)

Our article on electrolysis has a little discussion of efficiencies, in which it says (among other things) "For instance, when considering a power plant that converts the heat of nuclear reactions into hydrogen via electrolysis, the total efficiency is more like 25–40%". Possibly this is related to that? Although the Sulphiric acid article doesn't detail how much of the process that efficiency is for, and whether it is theoretical or practical. As to the first point, you'll have to wait for someone who knows more about the temperatures used in electrolysis than me. 86.139.237.132 15:33, 31 January 2007 (UTC)

Given that I'm fairly confident that this info is in error - I've moved it to Talk:Sulfuric_acid#Uses see there if you can help.87.102.7.133 15:42, 31 January 2007 (UTC)

Sound from Undersea High Voltage Wires

Is there any information about sound emission from undersea high voltage transmission wires as from wind powered generation stations?Specifically doea it have any impact on marine life?

Kingscreek 14:58, 31 January 2007 (UTC)

Some of the latest plans call for High-voltage direct current (HVDC) transmission; these should be relatively quiet. And most power cabling systems should be relatively free from producing externally-detectable magnetic or electrostatic fields.

Atlant 15:53, 31 January 2007 (UTC)

Depends what you mean by sound. Partial discharge in cables can emit ultrasound--Light current 17:07, 31 January 2007 (UTC)

Partial discharges in cables are pretty serious, and after enough of them have happened the cable will fail and have to be replaced. Cable failure would be a rare but explosive phenomenon. Partial discharge should not be an ongoing phenomenon like the sizzling heard from overhead high voltage lines. A power cable may have three phase AC inside a shielded jacket, producing little external electrircal or magnetic field if the phase currents are balanced. If the 3 currents are unequal, then there will be a magnetic field external to the cable equivlent to the imbalance. They might hum at the powerline frequency and many harmonics. DC or AC cables would be warm if carrying an appreciable current, and marine life might seek or avoid the warmth. DC cables are often unipolar (carrying current in 1 direction on isolated cables), and if it carries several hundred amps, it would produce a strong magnetic field which would affect a magnetic compass or any biological creature sensitive to magnetic fields. Edison 18:07, 31 January 2007 (UTC)

A wind farm has been proposed to generate electricity off of the coast of Delaware and one of the objections offered is that the undersea cable will emit sounds that will harm the marine life.The definition of sound in this context is any wave emission that can be heard or felt by marine creatures and may influence their existence. I believe that Edison addressed this very well theoretically but I wonder if there is any actual experience. 141.151.14.252 21:53, 31 January 2007 (UTC)

I have spent time in close proximity to insulated and shielded cables carrying hundred of amps at voltages up to 138 kv and heard no sound at all coming from them. Overhead open-air conductors may sizzle a bit from corona discharge.Edison 15:51, 1 February 2007 (UTC)

periodic properties

why properties of elements are the periodic functions of their atomic numbers but not of their atomic weights?

See atomic number vs atomic weight.In a nutshell, weight includes neutrons which don't generally get involved in reactions.The atomic number is the number of protons, and therefore, electrons.Electrons are a large part of what makes things react the way they do, so chemical properties of elements will depend largely on electrons.(I'm sure I'm oversimplifying here, but this is the general idea I believe.) Friday (talk) 16:25, 31 January 2007 (UTC)

Pretty much all of chemistry boils down to the electric charge inherent in protons and electrons. That is to say, a chemical reaction is anything which happens because of these charges. Because a neutron has no charge, it has no effect on the atoms/molecules/ions formed: they will still have the same colour, reactivity etc.
That said, some properties do change slightly with atomic weight; the mass of an Avogadro number of Carbon-14 atoms would be 2g more than the mass of an Avogadro number Carbon-12, and as a result, the melting/boiling points of the Carbon would be slightly higher for C-14, because slightly more energy is required to get the particles moving at the same velocity. Heavy water is a good example of this; in heavy water, the hydrogen (¹H) is replaced by deuterium (²H), and as a result has a density of 1.1 g/ml, melts at 3.8°C, boils at 101.4°C and has a pH of 7.41. Heavy water is also slightly toxic as it can kill after about a week of drinking; normal water certainly wouldn't! Of course, the change in properties is miniscule, compared to that found by changing proton number (heavy water is far more like water than Hydrogen sulfide (H₂S), which boils at below room temp and kills in tiny doses!), so for every day chemistry, the effects are ignored. Laïka 17:08, 31 January 2007 (UTC)

I wonder, now that you mention it, about the relative specific heats of isotopically different substances — clearly the boiling point and such will be higher because temperature is energy per degree of freedom and you get more kinetic energy but don't get more DOF just from having a neutron, but might it just be proportional to the added mass?In that sense it would be interesting because the higher-mass-number substance would act just like the other kind but with fewer atoms taking part (or the other way for light isotopes, of course).What other properties might "unexpectedly" not change?--Tardis 22:15, 31 January 2007 (UTC)

Meat that grows on trees

Literally or not. :) How long until we can produce artificial meat in laboratories, and make it an industry? 81.93.102.33 17:16, 31 January 2007 (UTC)

Not too long -- the Tissue engineering article may give you some ideas. For a practical example, see Artificial urinary bladder.

Atlant 17:23, 31 January 2007 (UTC)

Of course, it rather depends on what you call meat (which literally means food). See meat analogue (not to mention sausages, burgers, Spam, etc).--Shantavira 18:14, 31 January 2007 (UTC)

Mmm spam which is what this comment is (Just kidding). Well with the recent advances in tech such as cloning and stem cell reasearch the chances for you acctually eating artifically created meat and by products are becomming higher I saw this on How stuff works ill look up that link for ya. in any ways they say that the taste is exactly the same the only way to tell the diff is if the company lables the product. ill be back with that info for you after i eatMaverick423 19:05, 31 January 2007 (UTC)

http://home.howstuffworks.com/cloned-meat.htm Here is the link i promised ya Maverick423 19:07, 31 January 2007 (UTC)

Thanks a lot for this link, though I was actually looking for meat which is made without there ever being a cow or any sentient being in the process of making it. Lots of thanks to the rest, who took the time to answer. :) 81.93.102.33 19:23, 31 January 2007 (UTC)

Synthetic meat? Sounds yummy. − Twas Now ( talk • contribs • e-mail ) 19:36, 31 January 2007 (UTC)

Hey that does sound intresting Maverick423 20:20, 31 January 2007 (UTC)

In the article I read from NASA on that it said they grew a steak, but it tasted terrible because they grew it and didn't kill it. All the cells were of the same kind, there wasn't all the different kinds and chemicals you'd find in a real steak. I'm sure they could get it right soon though! [Mαc Δαvιs] X (How's my driving?) ❖ 00:49, 1 February 2007 (UTC)

Can we just tie it to a tree and call it 'veal?'Tree steak is delicious :).--OpusPenguin 02:26, 1 February 2007 (UTC)

Hmm, I wouldn't buy an artificial meat product myself, but a natural meat alternative I'd be open to. A lot of this has to do with how they could SELL such a product. 67.174.211.89 06:03, 1 February 2007 (UTC)

I would buy anything that tastes good. :) [Mαc Δαvιs] X (How's my driving?) ❖ 12:55, 1 February 2007 (UTC)

Meat that grew on trees would rot. As for meat grown in a laboratory... well, you would have to wonder whether it would be more economical than the natural method. The ingredients/chemicals required to make the meat would have to come from somewhere. I can't imagine that, whatever substance was used, that it would be cheaper than grass. BenC7 06:54, 1 February 2007 (UTC)

heh Mαc Δαvιs has the right idea! if it looks good eat it!! wait i guess it has to taste good too =( Maverick423 15:04, 1 February 2007 (UTC)

Here you can see how mutton meat grows on trees.  --Lambiam^Talk 00:26, 2 February 2007 (UTC)

Some would call factory farming a laboratory or industry.Political connotations aside, it is quite true that modern agricultural engineering uses a lot of science, chemistry, and other techniques to get more meat (or milk or eggs or whatever else) than a ("so-called") natural animal would produce. Nimur 07:51, 2 February 2007 (UTC)

Insulin Pump

I am enquiring about changing my Diabetes Type 1 therapy to that of an insulin pump, but I am havnig a few worries or questions I'd li ke to resolve before speaking to the doctor. I would like to know how often I would have to fill up the resevoir; i.e. daily, bidaily etc.

I would also like to know if there are any available that actively monitor blood sugar levels and automatically calculates volume of insulin to emit.

Finally, personally do many of you think it is easier and more convenient than injecting insulin 4 times a day, plus Insulatard at night.

Any help on this matter would be greatly appreciated.

There are many websites that describe pumps in detail, but here is an excellent one that also links to all the manufacturers' pages as well as discussion forums. [8]. In response to your other questions: most people fill the reservoir every 3 days when they change the infusion set; Medtronic's new model is combined with a continuous glucose sensor; all will calculate insulin if you enter glucose and carbs, none if don't; lots of people think it is easier and more convenient, lots don't like wearing such a thing. There are lots of more specialized discussion forums and chatlists that could give you better answers than here: try googling insulin pump discussion list or similar terms. Good luck. alteripse 01:06, 1 February 2007 (UTC)

Googled for insulin pump discussion and vendors. [9] Minimed has the model 522 and 722 pump which incorporates input from a real time sensor. The pump is expensive and the monitor sensors are expensive, so check for reimbursement from your insurance plan. The real time sensor is used to track trends, but you still do a finger-stick to get more accurate data for dosing and twice a day to calibrate the continuous sensor. The real time monitor can do something the regular meter cannot, which is to sound an alarm if your readings go too high or too low, which could be very helpful if you were sleeping or driving a car. Their smart pumps will accept readings wirelessly from from their finger-stick meter, accept your input of carbohydrate intake, and calculate the insulin dose. The 722 reservoir can hold 300 units for a large 3 day supply on one model, and for those with lesser neads a smaller model 522 with a smaller 176 unit reservoir is available. The latest book on smart insulin pumps, per Amazon.com, is "Pumping Insulin, 4th edition(2006) by John Walsh and Ruth Roberts, Torrey Pines Press. [10] is Insulin-pumpers.org, where you can register as a member and read the experiences of many pump users. We cannot give medical advice, such as which injection system is best for you. There are other vendors of pumps and other user groups as well. Get your doctor's recommendations if you are seeing a diabetes specialist. Good luck. Edison 16:11, 1 February 2007 (UTC)

Thanks for taking the trouble to find these additional specific references. I endorse them also, especially the Walsh and Roberts book for anyone who wants a how-to. alteripse 05:36, 2 February 2007 (UTC)

copper and plants

does anyone know what use copper has in plants? I'm writing up an experiment on the subject. Thanks! Jackacon 19:54, 31 January 2007 (UTC)

From a quick Google search, check this out: [11]. -- Scientizzle 20:10, 31 January 2007 (UTC)

great thanks a lot! Jackacon 20:59, 31 January 2007 (UTC)

Copper chlorophyllins are found in some foods:)Hidden secret 7 20:39, 3 February 2007 (UTC)

Please edit a page about Young-Earth creationism

I consider my self to be a Young-Earth Creationist that believes that most of the fossils came about from the flood. On this page (http://en.wikipedia.org/wiki/Old_Earth_creationism) under Progressive Creationism,it says, "It is usually only promoted by Old Earth creationists, as Young-Earth creationists see everything in the fossil record as being created in six 24-hour days." Can you please change this for me? Please check out this web site for more information, http://www.answersingenesis.org/home/area/overheads/pages/oh20010720_56.asp

Thank you. 134.39.245.102 20:09, 31 January 2007 (UTC)

(Edit conflict X2) You may want to try that yourself by pressing the edit button at the top of the page. However, editing such a page has been a mine field in the past, especially on the Dinosaur page which lead to the creation of various creationism pages. Before adding your own views, you may want to discuss it on the article's talk page or a relavent wikiproject. This will ensure your views are NPOV & aren't deleted or create an edit war. Make sure they are referenced as well. Hope this helps... Spawn Man 21:58, 31 January 2007 (UTC)

Hi and thanks for taking the time to post. The heading of that page has a box that says This article or section is in need of attention from an expert on the subject, this means information there may not be accurate as you have discovered. Wikipedia is a Encyclopaedia which can be edited by anyone, you have found sources to back up your argument which is a great start, have you considered contributing yourself? It is probably unlikely someone here on the science desk will be expert enough to want to edit an article concerning religion. Vespine 21:52, 31 January 2007 (UTC)

I've just removed the sentence rather than modifying it, as it didn't really make much sense. And it was non-factual, as you point out. BenC7 07:00, 1 February 2007 (UTC)

Can you really be an expert at religion? Is it a field? I personally like to call myself a world class expert at UFOology and of the leading fariyologists in the world—I've published many papers on the size, shape, and other properties of fairy wings. I suppose you could however, study history, or aspects, causes, etc. [Mαc Δαvιs] X (How's my driving?) ❖ 12:51, 1 February 2007 (UTC)

I believe that what your expertise falls under is cryptozoology although we get your point. You can however be an expert at religion, by studying it at university.... Spawn Man 21:38, 1 February 2007 (UTC)

If someone came into a US courtroom to testify as an expert on religion or anything else, they might testify that they had the highest degree in their field from an accredited organization, that they had worked in the field for many years, that they had published in the field in respected journals and written books published by respected publishers, that they had taken additional specialized training in the field to keep their knowledge current, that they had professional licensing in a field, that they were on the faculty at an accredited university in the field, and that they had testified in other cases as an expert. If they had merely read the Bible on their own, or were just a local preacher, or had posted to blogs about religion, or had books self-published or published by a partisan press, their side would have a hard time getting them accepted as an expert. Judges absolutely avoid getting into questions of religious truth or discipline within a religion. In the Scopes Trial in 1925, William Jennings Bryan who was prosecuting a teacher of evolution, was accepted by the defense as an expert on the Bible without many of these qualifications, so that the defense attorney, Clarence Darrow could expose creationist views on the stand, such as the first day of Creation having begun at nightfall preceding Sunday October 23, 4004 BC in the Julian calendar. Edison 16:26, 1 February 2007 (UTC)

Actually the rulings on how US courts recognize scientific expertise have changed quite considerably over the years. How expertise is recognized within given fields is often quite in flux as well, and with new fields can be a highly contentious area. I'm just pointing out that it's not easy to gauge in many cases, and the way the American legal system deals with it has never been set in stone (see the brief discussion at Scientific evidence (law)). --140.247.248.95 17:37, 1 February 2007 (UTC)

Learning style preference statistics

Please tell me where I can find the stat breakdown for how many learners are primarily:

Visual Aural Kinesthetic

I seem to remember reading it was 50% visuaL, 35% auditory and 15% kinesthetic. Who conducted research on this? Has it been verified?

Thanks!

Howard Gardner was the prominent psychologist that packaged and sold the different-learning-styles-idea. He has written about eight books, and categorized people's talents and strengths. A lot of what he says is common sense and logical, like some people are better at different things, like music, sports, visual art, etc. However it is taken to the extreme when one says everybody is gifted in some area, just not necessarily verbal/quantitative. His ideas were grasped strongly by gifted education circles a few years ago, but it has kind of gone out of style. You couldn't for sure group people into different categories of his, or anybody else's. Other psychologists have abbreviated his down to 3, some extended his up to 20 something. There may be numbers out there, but keep in mind it isn't for sure, and, after all, it is a test that they use to decide. [Mαc Δαvιs] X (How's my driving?) ❖ 00:47, 1 February 2007 (UTC)

I just did a quick search and found a study that used those categories of learning to investigate other things. In a study of 158 education students, about 94 were kinesthetic/tactile-dominant, 43 were visual, and 21 were auditory. I should emphasize that it would obviously be dangerous to generalize to the general population from a single survey, for a number of reasons (e.g., sample size, sample chosen). Someone else may be able to find some better stats. BenC7 07:13, 1 February 2007 (UTC)

Botrytis cinerea

Has the complete sequencing of the genome of the fungus, B. cinerea, been completed? - 210.86.33.83 22:03, 31 January 2007 (UTC)

Try using this resource. --JWSchmidt 02:52, 1 February 2007 (UTC)