Wikipedia:Reference desk/Archives/Science/2008 December 8

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December 8

Carbs from Vegetables

Sort of 3 questions:

1. Does anyone know of a place that lists the amount of carbohydrates, protien and fats in typical vegetables (brocolli, colliflower, protatoe, pumpkin, carrot, etc.)?

2. What is the scientific consensus on eating non-starch vegetables (ie no potatoe or pumpkin) as the only source of carbohydates in a diet (ie no bread/rice)? Not asking for medical opinion, I just want to know if scentifically the body can get all the carbs it needs from only non-starchy vegetables.

3.Before cultivation, what was the source of carbs for hunter/gatherers? And in what period did the majority of the earths population start eating mainly cultivated food instead of hunting/gathering for food. --Dacium (talk) 01:39, 8 December 2008 (UTC)

1. USDA food database

2. Humans don't need carbohydrates at all. See gluconeogenesis. If a chemical is classified as "nutritional fiber" that means that humans cannot digest it, and while human intestinal bacteria can digest some sorts of fiber, they (the bacteria) mostly live in the colon where monosaccharides cannot be absorbed into the body anyway. Icek (talk) 02:22, 8 December 2008 (UTC)

3. See Neolithic Revolution.

Icek (talk) 02:22, 8 December 2008 (UTC)

Thanks! About number 2, why is it that low carb diets seem to be not recommended scientifically? Upon reading most of the articles I could find here (such as low carb diets etc) it appears the lack of carbs itself is ok, but they don't recommend it because people eat to much fat or protien?

If a diet is just non-starch vegetables, eggs, nuts and lean meat (ie no excessive protien or fat), is it scientifically considered healthy?--Dacium (talk) 02:38, 8 December 2008 (UTC)

Actually, most recent science actually supports the low-carb, high-protein diet as the most healthy. The "low fat, high carb" diets of the past have been more recently shown to be quite a bit LESS healthy. This radio broadcast: [1] discussed in detail a recent Israeli study that compared 3 diets: The "atkins style" low carb diet, the "ornish-style" low fat diet, and the "mediterranean diet" seen as lying somewhere between the two. It found that the rank-order for healthful outcomes among practitioners of the diet was 1) Atkins 2) Mediterranean and 3) Low-Fat. Here is the original article, published in the New England Journal of Medicine: [2] Here's another article: [3] that cites two different studies from 2004 which show unequivocally that low-carb diets beat low-fat diets in lowering both blood cholesterol levels and blood triglyceride levels. We have a carry-over from the old days when "low fat" was everything, but most modern studies seem to be leaning more and more towards "low-carb" diets. --Jayron32.talk.contribs 03:47, 8 December 2008 (UTC)

The study you mention is a weight loss study. Even if a lot of people's health would benefit from losing weight, a healthy diet is a diet that keeps your weight the same, and that you can live on for years and years without suffering from any nutritial deficiencies. As for your claim that the high-protein diet is the most healthy, neither of the articles even discusses if people get enough vitamins and minerals when they eat low-carb, high-protein. I don't recommend eating rice or bread, but vegetables and fruit (= carbs) are important sources of vitamins and minerals. Lova Falk (talk) 20:56, 8 December 2008 (UTC)

When I hear people making such arguments about getting sufficient vitamins and minerals I wonder whether they don't realize that one can easily get these micronutrients in concentrated form e. g. as pills which is often more convenient than e. g. eating relatively large amounts of carrots for a little vitamin A. After all, scientists have figured out which chemicals are behind the vitamins; it's not like the 18th century when it was only known that lemons and sauerkraut prevent scurvy, it has been pinned down to ascorbic acid. So why not use modern science and technology? I don't want to say what's a healthy diet but that vitamin deficiencies are actually easily solvable problems (vitamin pills aren't expensive either).

By the way, it seems to me that the results from the NEJM article cited by Jayron32 has more to do with the psychology of eating habits than with healthy nutrition. Icek (talk) 01:31, 11 December 2008 (UTC)

This site has it all. -hydnjo talk 04:01, 8 December 2008 (UTC)

Non-starchy vegetables are generally high in sugars, so they do supply "carbs". They are generally also high in micronutrients and in fibre, which is why they are a useful part of the diet. If you fancy fish and broccoli for dinner, with no potatoes, go ahead, but adding one or two small potatoes won't kill you either. Itsmejudith (talk) 08:49, 8 December 2008 (UTC)

Mushroom Substrate

what makes a good mushroom substrate, that doesn't involve vermiculite? i can't find one on the internet so i'm asking u guys. —Preceding unsigned comment added by 76.14.124.175 (talk) 02:40, 8 December 2008 (UTC)

At Fungiculture we've got a substrate section[4]. And google has a range[5], but what is "good" needs someone who knows – Julia Rossi (talk) 02:48, 8 December 2008 (UTC)

thanks! —Preceding unsigned comment added by 76.14.124.175 (talk) 03:14, 8 December 2008 (UTC)

Fixed link – you're welcome,  : ) Julia Rossi (talk) 04:31, 8 December 2008 (UTC)

Penn & Teller ? StuRat (talk) 14:24, 8 December 2008 (UTC)

Compressing Water

I've heard that compressing water (like compressing air in an air compressor) is extremely difficult, borderline impossible. Why is this, when there is plenty of space between water molecules? [[User:Shane 42]] (talk) 04:09, 8 December 2008 (UTC)

There isn't much space between the liquid water molecules...when water changes from liquid to solid, it's volume actually increases! With most liquids the volume of the liquid and solid is the same - so most liquids are no more compressible than their corresponding solids. The molecules only separate out when they form a gas - ang from 20001 to 20002 atmospheres (perceived). Water is compressible, but only at pressures comparable to 20000 atmospheres. HTH, Robinh (talk) 08:14, 8 December 20d the volume of one gram of gaseous water (steam) is MUCH larger than one gram of liquid water or ice. Hence, steam is very compressible - but water and ice are not. SteveBaker (talk) 04:51, 8 December 2008 (UTC)

See equation of state#Other equations of state of interest (stiffened equation of state). Water is like air already under 20000 atmospheres, so changing from 1 to 2 atmospheres (real) pressure is like water changin08 (UTC)

Due to the hydrogen bonding between water molecules, there is actually little to no space between them - the formation of crystalline ice disrupts the hydrogen bonding, which is why water expands when it changes state to ice. Bobzchemist (talk) 18:07, 8 December 2008 (UTC)

UK DNA taken from criminals

How do the police get this? Kittybrewster ☎ 08:23, 8 December 2008 (UTC)

Usually with a cotton swab on the inside of the cheek.--Shantavira|^{feed me} 09:10, 8 December 2008 (UTC)

"So Mr Jones - would you care to explain how we came to find your DNA all over that cotton warehouse down by the docks on the night in question?" SteveBaker (talk) 13:56, 8 December 2008 (UTC)

Human body voltage

I just held the leads of my multimeter, and sure enough, there was a 60mV difference between my left hand and my right hand (the right hand being the "ground"). Sure enough, when I switched hands on the leads, it read -60mV, and when I let go, it popped back to 0, so I doubt it's a fluke of the multimeter itself.

Does anyone know of any articles or external links as to what my be causing a measurable electric potential between a human's extremities? And is it actually normal, or am I turning into Elle Bishop? :) --Link ^(t•c•m) 08:43, 8 December 2008 (UTC)

60mV is an incredibly small difference - it could easily be caused by some kind of inductive pickup in the wires leading to the meter. I would do two things:

1. Try doing the experiment while standing in different places in the room - also outdoors - and see if this number changes (I bet it does)
2. Try reversing the leads an seeing if it still reads 60mV-ish...which would suggest an inaccuracy in the meter.

I'm pretty sure you aren't abnormally turning into "The Human AA". Be careful with measuring yourself with a meter...people have died trying to accurately measure their resistance on the ohms scale! (Although you should be OK on the volts scale).

SteveBaker (talk) 13:54, 8 December 2008 (UTC)

Indeed - be careful! Whatever you do don't pierce the skin, once you are through the skin your resistance is very low and the high voltage used to measure it can kill you (as Steve says, measuring voltage should be safe, it's a pretty passive test, but it's not worth risking it). --Tango (talk) 15:29, 8 December 2008 (UTC)

That'd be very difficult to do with a battery-powered meter, as the voltage cannot be possibly higher than the one provided from the batteries, and, the last time I tried that, even the resistance between the two sides of my tongue was several kilohoms. -- Army1987 – Deeds, not words. 15:35, 8 December 2008 (UTC)

The thing about measuring across the tongue is that your heart isn't on the path between the two probes - so it's relatively safe (I say relatively - because if one hand happens to be touching some metal part of the meter...and the other probe is on your tongue - then maybe you are still in trouble). But measuring resistance from one hand to the other puts your heart right in the firing line. The "I did it and got away with it" argument also applies to crossing freeways while blindfolded. SteveBaker (talk) 16:37, 8 December 2008 (UTC)

Nevertheless, it has happened. The voltage can easily be higher than that of the batteries, you just need a transformer, although actually now I think about it is probably current that is the risk, not voltage. --Tango (talk) 15:38, 8 December 2008 (UTC)

It's the current that's the danger, I think there was a Darwin Award for someone who killed himself with a multimeter - the electrodes pierced his skin, and the current caused a heart attack. DuncanHill (talk) 15:41, 8 December 2008 (UTC)

In this case, the current isn't enough to zap and kill a person. However, it is enough to cause fibrillation. The chance of fibrillation in a healthy adult is small. In a person with a pacemaker or heart disease, the risk is increased. Whenever I hear about the volt/current argument, I can't help but remember reading specs on a railgun that used a teravolt generator that had very low current. The warning was: "They say volts won't kill you. That is true. A few thousand teravolts won't kill you. It will vaporize you." -- kainaw™ 15:52, 8 December 2008 (UTC)

Yes, the current is the danger (or more precisely the charge, you need around 60 mC IIRC), that's why I mentioned my resistance. Assuming the ohmmeter uses 4.5 V, and a resistance of 30 kΩ, you'd get 0.15 mA, so you'd need to wait 400 seconds before any significant danger. YΩMV, but I don't think that in "normal" circumstances you could get a much higher current through your body with a "normal" multimeter. (BTW, are there really transformers working with DC?) -- Army1987 – Deeds, not words. 16:03, 8 December 2008 (UTC)

Every time I say this - we have the same debate - the fact is that more than one person has actually, for real, died from doing this. So if your theory says that it can't happen then you need to find a new theory because your old one just met with reality and didn't come off so well! SteveBaker (talk) 16:37, 8 December 2008 (UTC)

Where did you get the 30kΩ figure? Are you remembering that we're talking about the resistance of the inside of the body (you have to pierce the skin first) which is essentially salt water? Salt water has a pretty low resistance. --Tango (talk) 16:43, 8 December 2008 (UTC)

Sorry, but can we have a WP:RS that says that someone died from the electric shock of a passively used multimeter? I can easily imagine all kinds of accidents with a multimeter and live cables, but I have trouble believing in the lethal power of a bog-standard battery that is used in many millions of toys without adding in a lot of stupid-smart electronics. --Stephan Schulz (talk) 16:47, 8 December 2008 (UTC)

The award Duncan refers to is at http://darwinawards.com/darwin/darwin1999-50.html. I had not understood that the winner had done that. If you reach blood, resistance will be low enough. (But it's somewhat unlikely to happen accidentally, at both terminals. And measuring voltage as the OP was doing shouldn't be very dangerous.) -- Army1987 – Deeds, not words. 16:52, 8 December 2008 (UTC)

I haven't re-read the Darwin award, but I believe it was done intentionally. I agree it's not likely to happen by accident, but nevertheless caution is warranted. --Tango (talk) 17:06, 8 December 2008 (UTC)

← (e.c.) Also, if you have a pacemaker you can kill yourself with a smaller current, indeed those body fat measuring scales recommend that pacemaker users don't use them. -- Army1987 – Deeds, not words. 17:10, 8 December 2008 (UTC)

A factor that must be considered is the internal resistance of the voltage source. If the internal resistance is high, it will reduce the current for any given external resistance. That's why "shocking coils" do not harm people. —Preceding unsigned comment added by 98.17.46.132 (talk) 17:20, 8 December 2008 (UTC)

I think stun guns have caused death. Does anybody know the open-circuit voltage of a typical stun gun? ("Open circuit" means measured with a very high-resistance voltmeter. I don't think voltage can be measured without imposing some sort of load - shades of Heisenberg.) Some stun guns use body contact from 2 prods. Others use penetrating barbs on the end of wires; the barbs benetrate the skin and stick there to give the shock. The barb kind is obviously more dangerous, unless the prod type touches an open cut, mosquito bite, etc. Sweat on the skin also enters into it. —Preceding unsigned comment added by 98.17.46.132 (talk) 17:40, 8 December 2008 (UTC)

Does anybody know the internal resistance of a typical stun gun? If the internal resistance and open-circuit voltage are known, the current can be calculated for any given external load. If the external load is assumed to be zero, that will reveal the maximum current that the stun gun can impose. It should be less than lethal. —Preceding unsigned comment added by 98.17.46.132 (talk) 18:02, 8 December 2008 (UTC)

Are you claiming that a stun gun applied to the internal body (below the heavily resistant human skin) is in no way lethal? Much of this topic is discussing the possibility of harm or death by applying voltage/current below the skin - especially to the blood, which is highly conductive. -- kainaw™ 18:25, 8 December 2008 (UTC)

In general, the probes for a stun gun should be close together, which would make the current path relatively local. This would tend to reduce the risk of applying fatal current to the heart, and is rather different than applying a multimeter or other current source to both hands. Dragons flight (talk) 19:08, 8 December 2008 (UTC)

I don't believe the Darwin Awards story. Just because some guy from the US Navy says it's true doesn't make it true. Note the word "Unconfirmed" at the top of the article. Where is the original report? And if you can kill yourself with a 9-volt battery and two pins, why has it happened only once in recorded history? And why never with a 12-volt car battery, or a 9-volt plug-top transformer, or a PC motherboard with all those jumper pins sticking up?

Anyway, returning to the question, I can get very close to the same results as the OP if I repeat the experiment enough times. Most of the time, though, the readings are apparently random in polarity and magnitude. My guess is that the voltage across your fingers is some messy waveform related to the sinusoidal mains voltage that your body picks up like an antenna, and to your body position and skin resistance. A cheap DVM set to DC will probably convert this waveform into a more or less random reading depending on the shape of the waveform. If you've ever looked at the waveform on an oscilloscope when you hold a high-impedance scope probe in your finger then you'll know what I mean. Imagine that the DVM is taking samples at random points on that waveform, or at least trying to average it with a very poor averaging circuit. --Heron (talk) 20:50, 8 December 2008 (UTC)

Electrical current flow in the human body is 3-dimensional. Usually, we think of electrical current as electrons flowing between 2 points in a narrow stream through a wire - essentially a 1-dimensional flow. However, electrons repel each other, so the flow in a 3-dimensional conductor is different. The following simple demonstration will show this. Fill a cup or glass nearly full with tap water. Dissolve some table salt in the water. Put the two prods of an ohmmeter in the water and adjust the meter to show the resistance between the prods. Now move the prods closer together, then farther apart. There will be no noticeable difference in resistance regardless of the spacing of the prods. This is because the electrons can spread out and have a great many parallel paths between the two prods. Unlike a typical wire-resistance measurement (essentially one-dimensional), the width of the salt-water conductor is very large compared to the distance between the prods - hence the current path is 3-dimensional. (The current flow resembles, in 3 dimensions, the "lines of magnetic force" shown by iron filings on a sheet of paper placed over a bar magnet.) Some electrons in the salt water demo will actually move away from the positive electrical pole at first, then swing around toward it. Between the two electrical poles, electron distribution will have approximately an even density across all parts of a plane normal to electron flow. (The boundaries of the cup or glass, and the surface of the water, are the approximating factor, as compared to a container of infinite size.) In the human body, electrical current from an externally-applied voltage will flow in the same manner. If a voltage is imposed between two points on the torso on opposite sides of the heart, and the heart is not directly between those two points, the spread-out of current will still give the heart the full current of that plane. (A complicating factor is that different bodily organs will have a different specific resistance. The outer boundary of the body is another complicating factor.) If a voltage is imposed at two points on the same arm or leg, the heart will experience very little of the current. So it is torso-applied voltage, or hand-to-hand applied voltage, that is lethal when the voltage is sufficiently high and the internal resistance of the voltage source is sufficiently low. —Preceding unsigned comment added by 98.17.46.132 (talk) 21:06, 8 December 2008 (UTC)

A 60mV difference is nothing. There's about a 200 V difference in the air between your head and your feet: [6], due to the inherent potential gradient in the atmosphere... --Jayron32.talk.contribs 21:59, 8 December 2008 (UTC)

Hold on there. Between two points, vertically spaced with 2 metres, there might be a 200 volt voltage, but only until you connect the points with a human body or another conducting object. When you do that, you short-circuit the voltage you originally had. As an equivalent example, consider a 9 volt battery. What is the voltage between the electrodes? It's 9 volts, of course, but what happens if you connect them with a piece of wire? The voltage drops to essentially zero. —Bromskloss (talk) 13:05, 9 December 2008 (UTC)

This anecdote of death by Simpson 260 sounds like an urban legend, since the meter does not place a 9 volt battery in series with the two test leads. Instead it has circuitry including the calibration rheostat, perhaps scaling resistors, and the meter movement in series. The present Simpson 260 manual [7] says (p9) the maximum short-circuit current on the ohms times 10000 scale, where the 9 volt battery is used, is 75 microamperes. For the RX1 and RX100 scales, it uses just a 1.5 volt battery. The meter movement itself is 20,000 ohms per volt and 50 microamperes full scale. The short circuit current on the RX1 scale is 125 mA, but note that is for a SHORT CIRCUIT, which the human body is not. I have seen safety bulletins in the past which contained myths intended to scare readers away from doing things which might lead to injury, such as if a person did the meter experiment with a source of greater current at higher voltage, or with an ammeter and a high energy source. I do not deny that under contrived conditions such as implanted electrodes it might be possible to cause electrocution with a 9 v battery. Edison (talk) 04:02, 10 December 2008 (UTC)

The following site says there has been several hundred deaths from stun guns in Britain alone. It also says 50,000 is typical for a barb type stun gun. —Preceding unsigned comment added by 98.17.46.132 (talk) 06:39, 11 December 2008 (UTC)

Here is the web site I mentioned above:

http://www.csmonitor.com/2008/1211/p01s01-wogn.html

The voltage for the barb-type stun guns mentioned is 50,000 volts. The internal resistance of the voltage source is not mentioned. Also, the stun-gun deaths were 320 in the US and Canada.

Longevity

I was just wondering - even if we extend average life expectancy to beyond 90 or 100, wouldn't we spend a good chunk of those last years blind deaf and frail - as we haven't worked out how to fix age-based deterioration in sight and hearing amongst other things. Paul Austin (talk) 11:09, 8 December 2008 (UTC)

Well, my visual prosthesis and cochlear implants are working fine, but that doesn't help my ... other thing ...begins with "m" ... what was the question ? Gandalf61 (talk) 12:19, 8 December 2008 (UTC)

Actually - I think the reverse is true. We've made such improvements in fixing things like eyesight, hearing and such that now we find many people are dying while they still have a lot of productive years ahead of them. SteveBaker (talk) 13:48, 8 December 2008 (UTC)

Have we really? My aunt is slowly getting blind and there is nothing anybody can do about it (I don't know her condition). Anyway, instead of jokes and opinions, isn't there any research done? The quality of the last ten years of people's life now compared to a previous period. Should be possible to do, but has anybody done it? Lova Falk (talk) 16:51, 8 December 2008 (UTC)

Actually, I am going to disagree with SteveBaker here. In the U.S. at least (can't speak for elsewhere) we have the means to both extend the life and improve the quality of that extended life; however we lack the political will to do so in an effective and equitable manner for all people. Essentially, the haphazard manner in which healthcare is handled in the U.S. actually provides both problems (i.e. people dying while still productive AND people living well past the usefullness of their own bodies). Both are solvable with modern medical technology; but given the poor access most people have to health care, it is likely we won't see any widespread universal system for providing both kinds of care to all people. --Jayron32.talk.contribs 21:54, 8 December 2008 (UTC)

I know a number of people in their 90's, in the U.S., who live self sufficiently and participate in a variety of activities. Time eventually catches up with them, but many have had a "hale and hearty" lifestyle well past 90. I knew a lady of 104 who was in a wheelchair and in a nursing home, but who could see and hear fine and was apparently of sound mind. Certainly some people have a stroke or Altzheimers decades earlier, or become blind or deaf. Edison (talk) 03:21, 10 December 2008 (UTC)

Island of Stability

Does anyone know of any images representing the graph of stabilities of nuclei, other than the one linked on the article? Specifically I was looking for something showing the 'sloping' of elements towards stability.

Cheers,

—Cyclonenim (talk · contribs · email) 14:27, 8 December 2008 (UTC)

In the first picture in the article Island of stability, height indicates stability, so you can really see that sloping towards the stable peak. Click on the picture to get a higher resolution, it was awfully hard to read on my screen at least. EverGreg (talk) 15:36, 8 December 2008 (UTC)

I agree that it's a good image and very helpful; however, I was looking for a kind of inverted image that showed the most stable nuceli in a sort of ditch. The reason for this was because the example we were given in class was like a ball rolling down a hill, and it'd be a good way to indicate it. —Cyclonenim (talk · contribs · email) 17:51, 8 December 2008 (UTC)

Wikipedia, Censorship and Child Pornography

I was reading about how the UK has banned the Wikipedia article on the Scorpion's Virgin Killer because the original album cover had a naked child. I understand that Wikipedia is not censored. But it made me wonder what images are in the child pornography article. I hesitate to look at the article because I'm at work (not to mention I personally might find it disturbing). Can an editor upload hard-core child porn and justify it by saying Wikipedia isn't censored and that's what the article is about? Or how about showing the images that Gary Glitter was imprisoned for? 216.239.234.196 (talk) 18:20, 8 December 2008 (UTC)

An editor can upload any image and make any claim he or she would like to make. That doesn't mean that the other users have to accept it. With far more people acting in a sane and reasonable manner, those who just want to be a dick are kept in check. -- kainaw™ 18:23, 8 December 2008 (UTC)

For the record, child pornography presently has no images of children or of pornography. Dragons flight (talk) 18:26, 8 December 2008 (UTC)

Also, I think you misunderstand the whole not-censored idea. If something is morally opposed, Wikipedia will not remove it as it is not censored to personal belief. The only circumstance in which something is removed is if it is against the law where the servers are held (I think it's Los Angeles but I could be wrong). Child pornography images (not potential images but explicitly proven images) would have to be removed by law in LA. —Cyclonenim (talk · contribs · email) 18:35, 8 December 2008 (UTC)

Actually the servers live in Florida, but your point is otherwise correct. Dragons flight (talk) 18:59, 8 December 2008 (UTC)

So if Florida rules that Virgin Killer album is illegal, then it will be removed? What about images that have not yet been ruled child pornography? What's to stop somebody from uploading child porn images to the child porn page and then (accurately) claiming that if they haven't been ruled illegal yet, then they must stay? I guess the other editors, right?

Also, I just realized that I accidentally posted this to the Science desk. I meant to put it in the Humanities desk. Is it OK if I move it? 216.239.234.196 (talk) 19:06, 8 December 2008 (UTC)

You can move the question, but it has already been answered. One user demanding that an image is legal and must be kept is not enough to keep it on Wikipedia. This is a community. One use cannot force an image to be on a page against the wishes of the community. So, the community will keep a user from exploiting Wikipedia policies to be an annoyance. -- kainaw™ 19:09, 8 December 2008 (UTC)

See the Miller Test. I think everyone would agree that an album cover has "artistic merit", and so is going to be legal in the US pretty much regardless. Though we don't have the finality of a court of law, I think in general Wikipedians are likely to apply a similar standard to Miller in deciding whether something should be included or not. Dragons flight (talk) 19:13, 8 December 2008 (UTC)

It also should be noted that the furor over this album cover is rediculous. I can buy this album, underage penis and all, at my local WalMart. I checked. The greater issues are legion, however:

1. A non-governmental agency is allowed to control content for ISPs which cover 95% of Britain, without means for formal redress should mistakes be found.
2. The method of censorship is unneccesarily disruptive (the use of transparent proxies) where other, less disruptive means are availible and easy to implement. The end result (preventing users from seeing the image) could have been achieved without funneling access from essentially all of the UK through 12 IPs. Furthermore, even using the transparent proxy method, the ISPs involved could implement an XFF standard which would essentially allow a users original IP address (and not the proxy's) to be seen by Wikipedia.
3. The censoring of the image can be easily bypassed by using subtle variations on the URL, which means that the censorship of the image itself is both unreasonably disruptive to the free flow of information (see above) and entirely ineffective in actually censoring the image.
4. The blacklist in question has blacklisted BOTH the image and the article about the album. One could make a justification for censoring the image which is consistant with "community standards" over child-pornography. However, the blocking of access to the text of the article, which contains nothing at all which could be construed as pornographic, is outrageous, and is again why problem #1 (having no means of redress) is such an issue.
5. The parties involved (the ISPs individually and the IWF specifically) have been unreasonably flippant about working with Wikipedia or the Wikimedia Foundation to solve the problem, despite the relative easy with which a solution could be worked out, and the potential media shitstorm that could result by being so flippant. If the IWF or the involved ISPs responded to the problem in a reasonable manner, this would have been solved days ago. The fact that they seem to be uninterested in working out a solution has resulted in an unneccesary escalation of the problem in the media, which is NEVER a desirable outcome.

None of these problems have anything at all to do with the actual censorship of the objectionable image. Arguements could still be made that the image should be censored; however that is NOT the major issue at hand here. The major issue is the irresponsible manner in which the involved parties have handled the censorship. --Jayron32.talk.contribs 21:10, 8 December 2008 (UTC)

For further info about the IWF blocking problem see Wikipedia:Administrators' noticeboard/2008 IWF action. Gwinva (talk) 21:34, 8 December 2008 (UTC)

Also, didn't Wikipedia move its servers to San Francisco? (Also I think the Nevermind album also has a similar image if I remember correctly but it doesn't seem to be banned). ~AH1^(TCU) 23:29, 8 December 2008 (UTC)

Servers still live in Florida. The administrative offices are in SF. Dragons flight (talk) 00:44, 9 December 2008 (UTC)

Yeah but the Nevermind album is a pic of the real life miracle of a babys ability to swim before he can walk. The other one is a picture of a little girl with something unusual looking around her vagina and, is it a picture of a "virgin killer" or a picture of what a "virgin killer" should or has targeted? Valid arguement against it but as per Wiki usual people will compare this picture to the Nevermind album, the added tasks and descisions regarding censorship, showing an oil painting of Mohammed and say "Oh if you censor that we wont be able to show anatomy or naked people kissing." Rubbish but hopeless to argue with. Well done for pointing it out anyway. It is a pity the word "pornography" dominates the debate about a picture which is obviously part of an artists protrayal of maliciousness towards a small girl. Sex is not evil but the creation of that album cover was certainly not all halos and polka dots. So long as people farm animals against their own animal cruelty laws, morals will be confusing unless directly affected in a negative way. Closed Community - 1 Wider Community - 0, Open to anything - 1 Open to everything - 0 ~ R.T.G 00:22, 9 December 2008 (UTC)

It is not proven despite numerous studies that the viewing of "real" child pornography, or violent pornography, leads to abuse or proves an intent to abuse. Therefore, anyone criminalized by viewing extreme material or mere nudity in the case of this image, is a victim of false abuse and imprisonment. Censorship is crime, as are visual pseudo-crime laws. It is interesting to conjecture the possibility of a libel action by those falsely accused of sexual criminality under these thought-crime laws. False abuse industry figures such as John Carr and Jim Gamble would be seriously out of pocket. This is nothing to do with protecting children from sexual predators-it is a moral crusade. —Preceding unsigned comment added by Trevor Loughlin (talk • contribs) 07:20, 9 December 2008 (UTC) Trevor Loughlin (talk) 07:21, 9 December 2008 (UTC)

Just as the word "pornography" is not the best description of the problem with this particular item, the claim of persecuting the viewer is not really a good part in this debate. Wise up Trev. You are defending the guy who breaks his ankle in a pot hole in case he is sued for the dangers the pot hole created... Censorship is a crime huh? Spitting on the phrase "moral crusade" in general... You probably have a low opinion of Mother Theresa. I am white. Bring back slavery I say. Two sugars please. Persons like you help to make drugs illegal because you prove that it may be absolutely neccesary because you do not respect the fact that some humans can be real evil fucks and we have all survived it. You would have it all go to crap and watch it just becase nobody has watched it going to crap for ages. Not one for the zoo or the carnival except a carnival of horrors. Sorry for the language. False abuse industry? Out of pocket? Stuff? Nonsense? Its as though some sort of group is trying to control our country by their own opinions. Prevent people having guns without a license? That would be a crime or a restriction or something. No difference between guns and candy floss. Every kid should want one. Blah. ~ R.T.G 12:45, 9 December 2008 (UTC)

You know, it brings up the question of "What is child pornography?". I don't find either image (Nirvana or Scorpions) remotely erotic. But maybe somebody else does? Out of 6 billion (or so) people on the planet, if one of them finds them erotic, is it child pornography? 216.239.234.196 (talk) 13:52, 9 December 2008 (UTC)

Unfortunately, that standard can never be applied with any sort of usefulness. There are people who get sexually aroused by pictures of clothed children, and yet we don't outlaw pictures of children altogether. In the U.S. the Miller test defines obscenity in all of its forms, though I can't speak to similar principles in other nations, I imagine some sort of "community standard" principle exists in many other nations. --Jayron32.talk.contribs 16:57, 9 December 2008 (UTC)

When I was small the film The Exorcist was banned. I thought there was too much hassle over films where people got hurt in similar ways you might see in an engineering mill or to much hassle over creatures which arent much more scary than your mild mannered dinosaur. As it turned out the film has stuff like a ten year old girl who when she is finished puking on hereself takes to stabbing her own vagina screaming "fuck me Jesus". The "Virgin Killer" piece is not the same as Nevermind. Again, talk about peoples ideas of clothed children... it's not quite hitting the button. The album definitly hits some sort of button. If it is not an erotic and/or abusive one... please go in to what it is because to be fair, what else is it? If it could be construed as something else it would be the first thing described rather than comparing it and defending it blindly. The only arguement here outside of quoting standards is that if one could watch paedophilia without joining in that it should be available to all. Who is up for that? I wonder. ~ R.T.G 00:11, 10 December 2008 (UTC)

Personally - I don't give a damn what sick shit people look at. What bothers me is what the kid went through in order for the picture to have been taken in the first place. We need laws that prevent those children from being involved - and to punish those who get the children involved. But once that has played out - what's done is done and the actual album cover is somewhat 'meh'. I don't have a problem with Wikipedia showing it in an appropriate context - just so long as we're not encouraging more people to do that kind of thing. The time to worry about this was when the album was released - and the people to hassle about it are the ones who commissioned, photographed, published, initially printed and violated the rights of that poor kid. They should all have gone to jail. SteveBaker (talk) 02:43, 10 December 2008 (UTC)

• Since this is a ref desk, not an opinion post, I'm not sure we need do much more here than direct the OP to Internet Watch Foundation and Wikipedia which covers the issue and provides links to various media commentaries. Gwinva (talk) 02:50, 10 December 2008 (UTC)

Yeah Gwinva but it is so weird the way Wikipedia debates this topic. The main concensus is that anything goes, had better go and questioning that is something wrong. How weird is that? That girl, now a 40 or 50 year old lady has to make the psychology of not giving a shit or she does give one and feels bad forever. It's indecent (that doesnt mention anything about sex, clothes, community groups, local law anything it's very plain in its own right "virgin killer" destruction of innocence, poison of the mind pure and by design). ~ R.T.G 06:32, 10 December 2008 (UTC)

Post-docs

When did post-docs become the common path of career progression in the sciences? Our article on the topic doesn't provide much history. My impression is that pursuing faculty positions immediately following one's PhD used to be much more common in the sciences than it is today. Dragons flight (talk) 19:02, 8 December 2008 (UTC)

That's probably correct. The American Physical Society probably has the statistics on that. --98.217.8.46 (talk) 01:37, 9 December 2008 (UTC)

My guess is it coincided with the increase in number of PhDs compared to available faculty positions. This combined with the greater mobility and perhaps larger number of places countries likely to be of interest to a scientist Nil Einne (talk) 12:32, 11 December 2008 (UTC)

Continuously-cooling device?

Apparently some people from Stanford created a zero electricity cooling device, which you use by heating it over a fire, and then it cools way down to refrigerator-like temperatures.

First, I'm wondering how the device works. I wasn't able to much out about that. I'm guessing that it's some long-running endothermic reaction (which thus sucks in heat), which is jump-started by heating the chemicals up until the reaction starts. Is that likely?

Second, I'm wondering if there's anything theoretically against having the same system (if it indeed works as described above), where the chemical reaction starts at room-temperature (specifics of the actual chemicals used aside)? If so, would it "yo-yo" back and forth between freezing, warming back up to room temperature, and then freezing again? And, since there is an energy gradient from which presumably you can draw energy, would this provide a continual "free" energy source, which would gradually suck up heat from the Earth? (Yay! Free energy until we all freeze to death!)

Thanks! — Sam 63.138.152.238 (talk) 20:14, 8 December 2008 (UTC)

This isn't a new concept. It most likely works on the same principles as an icyball which I believe predates modern compression refrigerators. Unfortunately the process wouldn't work at room temperature so no free energy here.-- Mad031683 (talk) 21:03, 8 December 2008 (UTC)

(edit)I should actually read the articles I link, It's from the 20's though still not new. -- Mad031683 (talk) 21:05, 8 December 2008 (UTC)

Absorption refrigerator? ~ hydnjo talk 22:22, 8 December 2008 (UTC)

But is there anything against there being a chemical reaction of this kind that takes place at or below room temperature, besides the fact that none has been found (or is likely to be found) with what we have at our disposal? — Sam 146.115.120.108 (talk) 03:51, 9 December 2008 (UTC)

The laws of thermodynamics are a harsh mistress. Certainly there are chemical reactions that do these kinds of things - but the energy in that case comes from (or winds up in) the chemicals. That doesn't give you 'free energy' that gives you energy from reacting chemicals...which isn't 'free'. SteveBaker (talk) 04:18, 9 December 2008 (UTC)

If at any point you reach the conclusion that something provides "free energy" there's an error in your reasoning. The laws of thermodynamics are pretty fundamental to our understanding of the universe, something that violated them would invalidate every theory we have, which is problematic since we have working technology and centuries of experiment prove the laws to be true. -- Mad031683 (talk) 17:31, 9 December 2008 (UTC)

Traction for tires.

Static (non moving) friction is stronger than kinetic (sliding) friction. This means that once an object (such as tires) start to slide, it has less friction strength to push in the opposite direction. This is demonstrated when our car gets stuck in snow. It's easier to drive slowly out of being stuck than by trying to spin our tires. So why is it that dragsters spin their tires? They should have less available traction and thus just sit and spin.

A corollary to this question, if I may. Once I have an explanation of why dragsters spin their tires for more forward movement, I will want to know if it is possible to stop faster with the tires driven in reverse (naturally, being aware that the tires spinning in reverse will lose directional control, but that is not my present question).

Thankyou.

Doug —Preceding unsigned comment added by 192.30.202.21 (talk) 23:51, 8 December 2008 (UTC)

I thought they melted the tires a little so that it would stick to the track, providing greater grip. I'm sure you can find the answer on the appropriate wikipedia page. 96.242.34.226 (talk) 00:06, 9 December 2008 (UTC)

Yep, that's basically it. Per our article on burnouts, tires have more traction at higher temperatures, and the friction of an intentional burnout is the fastest way to boost tire temperature. As for braking, eh... bearing in mind that there's a mechanical distinction in attempting to drive the wheels backwards and actually doing so, I think the answer is still "no". A dragster at speed can easily lock the wheels (and start slipping) by simply braking (thus the drag chute). Spinning the wheels backwards would have no further effect and could prove damaging to the vehicle. — Lomn 00:47, 9 December 2008 (UTC)

Rubber is weird stuff - and (as is fairly obvious) it gets sticky as it gets close to melting. So hot tyres are sticky - and sticky is good. So they heat the tyres up by spinning them (often with bleach poured on the track to help soften them still more). But for the actual launch at the start of the run - the idea is to NOT spin the tyres. In Formula 1 car racing, the pit crews keep replacement tyres in electrically heated jackets so that they are nice and sticky when they are put on the car at the next pit stop. SteveBaker (talk) 02:15, 9 December 2008 (UTC)

I wonder if releasing the clutch at super high revs might snap something. Formula cars do a lap to warm the tires and they would be the best gripping tires around but apparently if you spun one you would wreck its grip and unbalance the steering very easily. Rally cars were made at one time that could almost compete with formula cars but they were so dangerous and after a few races they would be burnt and seize up so they did away with them. ~ R.T.G 02:47, 9 December 2008 (UTC)

Hang on one second...I've often read that to get the best start off the line you basically have to dump your clutch at high enough revs that traction would just about be broken. This is to get the engine into the power band as quickly as possible. It is supposed to be a fine balance between trying not to spin your wheels endlessly (i.e. not moving) vs. not spinning at all and "bogging down" at low revs far below the power band of the engine. It is also given as a reason why four-wheel drive cars are so difficult to launch, the apportionment of torque to all four wheels makes it harder to break traction. This is just what I read on the net and in magazines, if anyone can explain it in finer detail I'd much appreciate it. Also, given the torque and power curves of a Honda S2000 (apparently a notriously difficult car to launch), what is the optimum RPM to dump the clutch at? Zunaid 16:51, 10 December 2008 (UTC)

Yes - you want the most torque possible at the wheels - consistent with them rolling (and therefore maintaining static friction) rather than slipping (and therefore getting dynamic friction). Since static friction is greater than dynamic friction for almost all materials - this is the best you can do for maximum accelleration. Dumping the clutch at this optimal RPM is certainly one way to reach that goal. Although...letting it out a little more gently to get the car rolling before ALL of the power is applied might be fractionally better for a turbo-charged car. With a turbo, you need enough engine RPM to generate enough exhaust to get the turbo spinning. If that RPM produces more torque than your tyres can stand without spinning - then you have a nasty problem. In that case - you might want to rev the engine to the higher RPM level to get that turbo going - then either briefly drop them as you dump the clutch (the turbo will take a while to spin back down again...) or you can let go of the clutch a little more gently to give the car time to get rolling before you let the full power of the engine get to the wheels. However, a car that demands that you do that could REALLY use a different gear ratio for 1st gear and/or some better tyres!

Differentials are the enemy of fast launches because they feed more power to the wheel that's moving the fastest. This is great for going around corners - but crappy when you are trying to launch quickly. If just one of your wheels starts to slip (maybe because the road is worn a bit more smooth on one side than on the other - or one tyre has a little less tread left) - the diff will apply more power to that wheel - robbing power from the wheel that's gripping and making the slipping one slip much worse. This is a problem in two wheel drive as well as four - but in a 4 wheel drive vehicle, you'll probably have a front diff, a rear diff and a center diff - all fighting hard to find the wheel that's LEAST able to make the car go fast and give it all the power! The fix for THAT is sophisticated "limited slip" differentials, lockable differentials and (best of all) fancy computer controlled differentials that are tied into traction control and yaw rate sensors. With those things, you can get a faster launch because power is given to the SLOWEST wheel instead of the FASTEST.

Sadly, on most cheap modern cars without fancy differentials, etc, there is "traction control" - which is supposed to prevent wheel slip on launch by artificially limiting your revs. This sounds like a good thing - but they are typically tuned to preven slip with not-perfect, not-sticky tyres and relatively poor road surfaces. Hence they limit the revs to something below what your nice new semi-slicks are capable of on clean, dry pavement - also, when they do drop the revs, it takes the engine time to get back up where you want it when the traction controller finally decides to give you back the right pedal. That means that to get the best launch speed you (ironically) have to turn off the very system the manufacturers put in place to help you do this!

As for a Honda S2000...the only thing I know about it is that the radio antenna is a nice short rubbery one that happens to fit perfectly onto the stock MINI Cooper'S antenna base and which produces considerably less drag and better FM reception than the one that came with my car! Thank you Honda! So there is at least ONE thing you make which I really like. SteveBaker (talk) 22:26, 10 December 2008 (UTC)