Science desk
< May 13	<< Apr \| May \| Jun >>	May 15 >

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

May 14

MnO₂

Hello. If manganese(IV) oxide is ionic (not covalent), then why is it commonly called manganese dioxide? Calling MnO manganese monoxide is a little bit ridiculous. Thanks in advance. --Mayfare (talk) 00:55, 14 May 2008 (UTC)[reply]

So you can forget the roman numerals and everyone still knows what you're talking about? The term predates IUPAC, anyway. Someguy1221 (talk) 01:17, 14 May 2008 (UTC)[reply]

Well, the term dihydrogen monoxide is widely known. :D --JDitto (talk) 03:33, 14 May 2008 (UTC)[reply]

Natural vibration of solids

So I was thinking, if a solid already vibrates naturally, what happens if it's made to stop vibrating? Does the material become more durable or more brittle? Thanks. --JDitto (talk) 03:07, 14 May 2008 (UTC)[reply]

Vibration could be due to heat, impinging sound, impacts by particles. Removing the vibrations will be the same as removing heat, or lowering the temperature. The solid will contract, it may recrystallize in another form, it may become more brittle. If you reduce the temperature close to absolute zero you will minimize the vibrations, but you will still get quantum fluctuations or zero point energy. Graeme Bartlett (talk) 03:59, 14 May 2008 (UTC)[reply]

Other interesting properties will result if you can get the temperature extremely low, where the material is in the lowest quantum state. Friction can vanish in a supersolid, and with tighter and tighter upper bounds on temperature, and therefore momentum and movent of the sonstituent particles, the location of the solid becomes vague and a Bose-Einstein condensation occurs. Graeme Bartlett (talk) 04:14, 14 May 2008 (UTC)[reply]

PHYSICS- "FORCE"

Which force is responsible for the noise made by the dry hinge of the door? —Preceding unsigned comment added by 117.96.7.67 (talk) 05:35, 14 May 2008 (UTC)[reply]

Electrostatic (repulsion between the surfaces in the hinge) and gravity (attracts the door to the Earth) --Shniken1 (talk) 05:51, 14 May 2008 (UTC)[reply]

It's sound created by friction. Wisdom89 _{(_T / ^C)} 05:54, 14 May 2008 (UTC)[reply]

And as Shniken1 suggests, friction is one of the many manifestations of the electromagnetic force. Algebraist 08:48, 14 May 2008 (UTC)[reply]

More specifically, it's the stick-slip phenomenon that relates to the friction.

Atlant (talk) 13:00, 14 May 2008 (UTC)[reply]

technological pudding

What does it supposed to mean? --Omidinist (talk) 06:52, 14 May 2008 (UTC)[reply]

It would help if you could supply some context.--Shantavira|^{feed me} 07:14, 14 May 2008 (UTC)[reply]

"Modern science has succeeded in vastly increasing our knowledge of nature,
from the microworld of subatomic particles to the vastness of intergalactic space.
The proof is in the technological pudding"
(Clifford D. Conner, A People's History of Science, p. 497). --Omidinist (talk) 10:58, 14 May 2008 (UTC)[reply]

It is a rephraseing of "the proof of the pudding is in the eating". In this case, technology is the proof. 206.252.74.48 (talk) 12:26, 14 May 2008 (UTC)[reply]

Great. Thanks. --Omidinist (talk) 13:07, 14 May 2008 (UTC)[reply]

Auntie, what's the matter?

Is matter-antimatter annihilation the only way to obtain 100% conversion to energy? Clarityfiend (talk) 07:14, 14 May 2008 (UTC)[reply]

Even this is a problem as proton connecting with antiproton also produces electrons and positrons. Graeme Bartlett (talk) 11:27, 14 May 2008 (UTC)[reply]

It is far and away the closest approximation, however. — Lomn 13:11, 14 May 2008 (UTC)[reply]

Accretion onto a black hole is probably the runner up, with efficiencies in the double-digit percent range. -- Coneslayer (talk) 13:18, 14 May 2008 (UTC)[reply]

I think Hawking radiation has the same conversion rate as matter/antimatter. — DanielLC 20:35, 14 May 2008 (UTC)[reply]

CO2 + energy = fuel. But how?

Taking CO2 out of the atmosphere (or oceans) would get an extra impulse if we could do something useful with it. Such as make fuel. Since petrol is transformed into CO2, releasing energy, can't one do the reverse, take CO2 out of the atmoshere (or oceans), add energy and make a fuel, preferably one that cars can run on? In other words, I want to reverse the arrow in the exothermic reaction equation in the combustion article (eg with x=8 to make octane). But is this as simple as burning? And in what form would the energy then have to be added? Heat? Or can it also be electricity? Of course, plants do something like this with light through photosynthesis, but that has a maximum efficiency of 6%. Artificial photosynthesis is just in its early stages I understand and the first stage produces hydrogen, but it is going to take decades until the hydrogen economy has a complete infrastructure. And the second stage produces glucose, just like plant photosynthesis, something that existing cars can only use as an additive (as is done in Brazil). Is it difficult to produce the longer molecules in petrol that cars can use as-is? And which alkane would be the most logical choice? Octane seems like the most logical choice for the car, but how well can cars run on other hydrocarbons that might be more easily produced? Are longer chains more energetic?
Also, since chemical energy storage is all about the exchange of electrons (yes?), doesn't it make more sense to use those directly, in other words, use electricity for reduction to combine the short CO2 into long carbon chains?
In short, can windmills and solar cells produce petrol? And shouldn't we have a carbon energy article? After all, that is the driving force of life on earth.DirkvdM (talk) 07:48, 14 May 2008 (UTC)[reply]

Cars with proper engines run fine on alkohol or biodiesel, both of which are fairly easy to produce from e.g. plant matter. Current engines may have problems because the alternative fuels have different lubricating properties and may act as solvents for gaskets. But solutions for these problems exist - see e.g. Ethanol fuel in Brazil, a large country that is using bioalcohol as fuel for 30 years. Synthesizing e.g. octane from CO2 and, say, water, is certainly easily done in the lab, but I don't think that there is an efficient industrial process for doing this. --Stephan Schulz (talk) 08:50, 14 May 2008 (UTC)[reply]

Actually, I don't think turning CO2 into octane can be done easily/efficiently through chemical processes even at the laboratory scale. I'm sure it can be done, but there are quite a large number of steps along the way, plus wasted energy and lost material. Dragons flight (talk) 09:11, 14 May 2008 (UTC)[reply]

I did not say efficiently ;-). And I mean "easily" not as in "it takes a few minutes" but as in "a competent chemist with a laboratory and a library will figure out how to do it without new research". --Stephan Schulz (talk) 09:33, 14 May 2008 (UTC)[reply]

Bear in mind that even thoug biofuel or some alternative like hydrogen may be necessary for things like boats, planes and cars travelling long distances, a large proportion of human travel can probably occur with direct use of electricity. Intracity/commuter travel via trains and plug-in electric cars, long distance transport of good within a country or even between countries with trains. Shipping (with ships) is probably one of the most significant things going to require some form of fuel, but shipping is AFAIK already very efficient (see food miles) and may get even more so with a return to wind assisted shipping[1]. Whether this fuel will be in the form of synthetic petrol, biofuel, hydrogen or something else is anyones guess but at the moment petroleum is still cheap enough that it's unlikely to be a problem for the few things that actually need fuel. As others have stated, biofuel is actually fine as a fuel for cars, the bigger problem is the cost. Nil Einne (talk) 13:14, 14 May 2008 (UTC)[reply]

Shipping may be efficient but due to its fuel (bunker oil) is one of the most polluting.[2][3] Iceland is disscussing converting their fishing fleet to hydrogen power, however. Rmhermen (talk) 14:54, 14 May 2008 (UTC)[reply]

Also renewable power sources are not without issues, the biggest one being storage. Since most renewable sources are not reliable and depend on the conditions it's ideal if you can store the power for use when power output is low. Batteries are too low density for this sort of thing. Pumped hydro (which is inefficient and needs somewhere to store all the water) or using the energ to produce a fuel (hydrogen for example) is probably the best option we have nowadays. Nuclear power plants of course have a somewhat similar problem in that their output can only be regulated slowly unlike fuel power stations which can generally be shut down or start-ed up at will depending on need. Non-pumped hydro can of course be used as one source to release power at will although it may mean some 'waste' (when your power output from other sources is so high and your dam is full you just have to it go) and there is always the risk if you have exceptionally low rainfall you hydro backup will run out. You can of course at a pump to a hydro power plant in some instances. The other issue is of course availability. The desert is a very good place to make solar power plants but many are not surprisingly sparsely populated and deserts are quite far from a lot of Western Europe for example. So either you need very long power lines which of course means very high losses (unless you make a room temperature super conductor) or you need to convert the energy to some sort of fuel (hydrogen perhaps). You can of course build solar and other renewable power plants in Western Europe but for solar anyway deserts are probably close to being the best location. Nil Einne (talk) 15:59, 14 May 2008 (UTC)[reply]

Public transport and electric/hydrogen cars might be a nice ideal, but it will remain a reality for a long time that private cars running on petrol are the preferred mode of transport and we need something that works now. And what is un-pumped hydro and how do you let a car run on it? And transport of hydrogen and electricity is indeed more of a problem than a liquid (at room temperature) fuel. So that's why I want a liquid fuel. DirkvdM (talk) 10:46, 15 May 2008 (UTC)[reply]

"Unpumped Hydro" refers to normal water-power, using natural run-off (though usually dammed). "Pumped Hydro" is only a somewhat inefficient but cheap way to store surplus power for load equalizing. Essentially, when your grid is delivering more than you need (because of all the base load power stations running at the optimum level and low demand), you pump water from a lower reservoir back up the mountain. See Pumped-storage hydroelectricity. --Stephan Schulz (talk) 11:46, 15 May 2008 (UTC)[reply]

So back to my (now adapted) question. Is there a way to make a liquid fuel that existing cars can run on with CO2 and an electric charge? How can you make this form hydrocarbon chains? DirkvdM (talk) 10:46, 15 May 2008 (UTC)[reply]

If octane burns with oxygen to yield heat with products of combustion carbon dioxide and water, how much more energy would be required to reverse the process, ideally? What would be entailed in such a synthesis? Above it was said ""a competent chemist with a laboratory and a library will figure out how to do it without new research"." but what might go on in a future reaction vessel which had water, carbon dioxide and electricity as raw materials and octane as a product? Edison (talk) 19:13, 15 May 2008 (UTC)[reply]

In New Scientist magazine earlier this year there was an article using CO2 this way. It started with using a ceramic which was heated and cooled in a cycle to remove one oxygen to form CO gas. experimental stuff. Polypipe Wrangler (talk) 20:49, 15 May 2008 (UTC)[reply]

The chemists here have not shed much light on the mystery of how it could be done in the lab or scaled up to a synfuel factory. I found some discussion of the hydrogenation of carbon dioxide at [4]. I found a United States Patent 6987134 issued 17 Jan 2006 for a process [5]. Maybe Craig Venter can do it with Frankenscience: [6] , [7]. He says in 18 months he can have microorganisms pumping out octane from CO₂. Edison (talk) 22:29, 16 May 2008 (UTC)[reply]

Where to get the CO2 from

The above question led me to wonder where one could best get the CO2 from; So where are the CO2-concentrations highest? this source says the concentration in the oceans is 60 times higher than in the atmospere. I assume that is volume-based. But if that is averaged out for the atmosphere (to which height?) then that number doesn't help because I want to know how the concentrations compare at ground level (and surface level for the oceans, or is it more evenly distributed there?). Of course, there is also the question how easily the CO2 can be extracted from water or air, but that may be affected by the method by which it is transformed into fuel. DirkvdM (talk) 07:48, 14 May 2008 (UTC)[reply]

Well, currently the easiest way is to burn less fuel in the first place. The process of converting CO2 (probably plus water if you want petrol-like stuff) back into usable fuel is even in the theoretical best case less than 100% efficient - the second law of thermodynamics sees to that. In practice, the efficiency will be fairly abysmal, I suspect - heat engines are only at 40% or so with the currently feasible or even plausible future materials. So unless you have spare energy that is not from fossil fuels, its easier and more efficient to not produce CO2 in the first place. If you decide to extract CO2 anyways, because you have spare energy (Iceland comes to mind), there are two less hopeless ways of doing it. First, collect it where it is produced - at the tailpipe or the chimney. That way you have a decent concentration to start with. Secondly, the smart way it indeed to let plants do the collection and concentrate on the conversion of plant matter into fuel. Sure, photosynthesis may only be 6% efficient, but then the solar cells grow themselves for free. --Stephan Schulz (talk) 08:39, 14 May 2008 (UTC)[reply]

You really want CO2 in the sea. Assuming all factors are yielding positive for the local phytoplankton, including the ill-sought after iron, marine snow will be capable of bringing certain amounts down to several kilometers below sealevel, which in theory can help on the greenhouse effect. I digress on your topic, but thought this was a relevant and not uninteresting bit of information, as there's a certain level of "saturation" for CO2 in water, which phytoplankton has an impact on. 213.161.190.228 (talk) 11:16, 14 May 2008 (UTC)[reply]

If you want effortless biomass, so from a natural surrounding (forest or such), then efficiency is even less than 1%, I believe (that 6% is a theoretical maximum). And then you have to harvest that and convert it to a useable fuel, each with their own (in)efficiencies. In comparison, the efficiency of solar cells is over 10% (and rising).

Anyway, the question here is about the concentration in water or air. You've got a good point with the CO2 from tailpipe or chimney, but I'm thinking about a way to harvest wind energy at sea, so not near such CO2-sources. DirkvdM (talk) 11:27, 14 May 2008 (UTC)[reply]

You could put your turbine on the coast and then grow algae in a tank. As Stephan said your "production cost" would be minimal and you'd get at the CO2. If you use wastewater to feed the algae you might get a twofer. 71.236.23.111 (talk) 16:15, 14 May 2008 (UTC)[reply]

(EC) Don't forget you need a way to convery your electricity to some sort of fuel, so your 10% quickly goes out the window. If you're using CO2, it simply doesn't seem feasible to me since we not only have no way that I know of to convert it to a fuel in mass quantities that I'm aware of, you're also almost definitely going to have to concentrate it somehow which is not going to be cheap energy wise. Hydrogen might be a better bet but even it's still far from being practicable not to mention the infrastructure investments required. Bear in mind if you're using something like jatropha or palm oil you can use the oil as a fuel with minimal processing. Obviously the planting, growing and harvesting is not free but the biomass you have left behind is probably the biggest problem sicne you're losing a lot of what your producing which is why people are trying to find ways to convert it to something usable. Algae fuel is another alternative which removes the land issue and also should eb a lot easier to harvest etc, but we still don't have a good algae Nil Einne (talk) 16:20, 14 May 2008 (UTC)[reply]

You might be interested in this lecture. [8] Some of the base data is a bit out of date, but the general principles still apply for the most part. (I think you'll need one of the players to get the full lecture.) Lisa4edit (talk) 03:09, 15 May 2008 (UTC)[reply]

WMD

I recently read some facts on Weapon of mass destruction. I have some questions on WMD especailly about the destructive power.

How many nuclear warheads (each 15 KT) will be able to completely destroy a large city like the New York City?
Which is more dangerous - Biological weapons or nuclear weapons i.e. which have more destructive and killing efficiency?
What will be the effect on ecosystem of the planet as a whole if 1000 nuclear warheads (each 15 KT) are blasted above ground? Otolemur crassicaudatus (talk) 09:55, 14 May 2008 (UTC)[reply]

The first part is odd: 15kT is a tiny nuke, like the WW2 ones. Do you mean 15 MT TNT equivalence? What do you mean by completely destroy? Just killing all the people or completely incinerate the deepest cellar? The second part is a bit odd too: either could completely render humanity extinct. Presumably biological agents would always leave some non-human residue but so what. See Nuclear Winter for the third part. --BozMo talk 11:37, 14 May 2008 (UTC)T[reply]

He probably means something that terrorists could get ahold of. A terrorist isn't going to have a 15Mt weapon. They might be able to get a 15kt weapon, though—you could make something like that if you had the right materials and resources. No small, non-state entity is going to build a hydrogen bomb, though. --Captain Ref Desk (talk) 13:36, 14 May 2008 (UTC)[reply]

No idea.
Nukes are rare and expensive. It also needs technical knowledge to launch (you can't launch one on a slingshot) but is more devastating and efficient than bioweapons as it can affect larger areas. Bioweapons on the other hand is cheap, easily mass-produced and can be concocted in your parent's backyard. When released, it would only affect a small area and must be manually and stealthily released (you can't load a canister of virus/bacteria in a missile warhead, it will be incinerated) but the mass production part will compensate that disadvantage. Vaccines and drugs can also be used to diminish the weapon's effect so minus points on killing efficiency.
See Nuclear winter and the more poorly written Nuclear summer.--Lenticel ^(talk) 11:45, 14 May 2008 (UTC)[reply]

For the first question, I mean 15 KT TNT equivalence. I just want to know an estimation that approximately how much such nuclear overheads will be able to destroy cities like the New York City. Destruction means complete destruction of buildings, all major artificial structures including the entire city population. Otolemur crassicaudatus (talk) 11:50, 14 May 2008 (UTC)[reply]

Immediate total destruction will require an implausibly large number. Going for the last few survivors in deep cellars is extremely expensive. To destroy New York as a working community so that it will fall apart without massive outside help is only a few nukes, especially if this includes ground bursts with massive fallout. So what is your setting? A few terrorists exploding 4 bombs will do massive harm, but the city will be rebuilt. An all-out global nuclear war with a 4 bomb share for New York will probably finish the city, at least for generations, if not forever. Without the industrial base and organized society, rebuilding will not happen. --Stephan Schulz (talk) 12:07, 14 May 2008 (UTC)[reply]

I do understand the cities will be rebuilt. I have only confusion about how many weapons will be able to destroy a big city. Tokyo is the most populous city in the world with a population of 33,600,000. During the Atomic bombings of Hiroshima and Nagasaki, Hiroshima's population was 255,000 and 140,000 people died in Hiroshima within 1945. Hiroshima has an area of 905.01 km². Tokyo has an area of 2,187.08 km² i.e. approximately four times of Hiroshima. Little Boy dropped over Hiroshima had an yield equivalent to 13 kt TNT. So an estimation can be made from this that to completely destroy Tokyo, at least 4 Little-boy sized nuclear weapons will be needed. And to completely destroy the New York City also, at least 4 Little boy sized nuclear weapons (each having an yield equivalent to 13-15 kt TNT) will be needed. Is the calculation right? Otolemur crassicaudatus (talk) 12:41, 14 May 2008 (UTC)[reply]

That's not correct per your criteria above. Hiroshima was far from "completely wiped out"; the Hiroshima Peace Memorial survived being only 150m from Little Boy's hypocenter; at least one person survived only 100m away. Even one nuke is enough to do massive harm; as Stephan Schulz said, complete destruction per your standards is utterly implausible. — Lomn 13:09, 14 May 2008 (UTC)[reply]

(ec, and somewhat repetitive now): Again, this depends on your definition. Strongly-built structures in Hiroshima withstood the blast even near ground zero, and there were even survivors (someone in a bank vault, I think) close to ground zero. Also, much of Hiroshima was lightly-build. Modern skyscrapers probably can withstand the blast better. As a lower bound, and depending on the definition of "destruction", your estimate may be right. But a single 15MT explosion will have a much stronger effect on most targets... --Stephan Schulz (talk) 13:30, 14 May 2008 (UTC)[reply]

1. A 15kt nuclear weapon would have a radius of total destruction of about 1.81 km / 1.12 mi (high blast pressure + fireball + ionizing radiation), or around 10 km²/ 4 mi². Just eyeballing it, you'd need around 10-12 or so if you were totally ignoring the effects of fire (which is hard to predict, but caused most of the damage and death at Hiroshima and Nagasaki). Or, if you had just 1Mt warhead, that would do the trick in taking out all of Manhattan and most of the surrounding boroughs.

2. It depends who has them and who is going to use them and how many are going to be used and so forth. Personally I think nuclear arms are easier to control that biological arms, but a well-placed nuclear weapon can easily be more destructive than biological weapon.

3. Where, presumably, are 1000 15kt weapons to be found? Now you're into the realm of talking about the arsenals of states, which are not 15kt fission weapons, but in 100s of kts in fission-fusion weapons, which have a very different fallout profile. --Captain Ref Desk (talk) 13:36, 14 May 2008 (UTC)[reply]

Check out list of nuclear tests to see just how little 1000 * 15kt is compared to the atmospheric testing that actually was done. Just the Tsar Bomba alone is several times higher yield than those 1000 bombs put together, although yield is not the most important factor in determining environmental effects. --Sean 14:24, 14 May 2008 (UTC)[reply]

The fact is that we do not know what the effects of modern biological weapons would be because they were never used. Lenticel's comment above is incorrect in that highly effective agents cannot simply be prepared in your backyard and biological agents were certainly planned to be deployed by missiles - even as recently as in Iraq. While toxin-type biological weapons (which require contact with the deployed agent) would probably not approach the death tolls of a nuclear blast, infectious-type weapons (which only require contact with an infected victim) might be another matter. Let's hope we never find out. Rmhermen (talk) 14:40, 14 May 2008 (UTC)[reply]

It's exciting to be able to fill your brain with so much information, but then it begins to itch. You want to share this knowledge to an equal intellengent person who might understand. But, as I heard befor -you can get so busy thinking up answers the question you might have though: should you share. You guys are talking Monsters. Your wilding the answers around on an open page like a kid with toy gun to some you don't even know and in todays world Monsters aren't the same as 20-30 years ago and neither are people. I know you can hungerly serch for answers, but some answers will give you nightmares for the rest of your life. Sharing these answers stuck in your Pandor's Box while may seam relaxing but your the one that hurt your brain. You need to be responsible for your Monsters. Keeper of WMD. —Preceding unsigned comment added by 69.44.236.100 (talk) 15:12, 14 May 2008 (UTC)[reply]

... what? Nimur (talk) 16:24, 14 May 2008 (UTC)[reply]

Um... If some 'mad terrorist' who wants to destroy the world is relying on the reference desk to find out the potential destructive power of nuclear and biological weapons, I think we're safe especially since the biggest problem is not knowing how destructive they can be, but actually producing them Nil Einne (talk) 16:27, 14 May 2008 (UTC)[reply]

It may also be worth pointing out that security through obscurity is not highly regarded as a defense mechanism. Open access to information encourages effective defense systems. Nimur (talk) 16:35, 14 May 2008 (UTC)[reply]

In any case, none of these questions would be useful in destroying anything. They're just about effects, and are easy to look up. You want to stop nuclear terrorism? Encourage your governments to do more to help secure nuclear materials in unstable countries. Encourage them to move towards more open relations with countries that stand a high chance of proliferation—the biggest antidote for proliferation is increased openness and exchange, it makes it both harder to hide and reduces the motivation. People asking questions on the internet has nothing to do with proliferation or terrorism. Knowing how many nuclear weapons it takes to destroy New York isn't going to help anybody out at actually doing it. --98.217.8.46 (talk) 02:08, 15 May 2008 (UTC)[reply]

For question 2, I'd say bioweapons have the potential to be more dangerous than nukes. If a bioweapon could be developed that is highly infectious, say being both airborne and waterborne, 100% fatal, and has a long incubation period, say a year, it could wipe out almost all of humanity. The long incubation period would give infected people more time to spread the disease before they show symptoms and also would delay work on a cure and/or isolation measures until everyone was already infected. StuRat (talk) 12:14, 16 May 2008 (UTC)[reply]

A more effective way to cause massive damage is to alter the course of an asteroid to make it hit the desired target. This can also be used to our benfit. E.g. if we know that the Yellowstone supervolcano will erupt within, say, the next century, we could evacuate the entire US and then let a 1 km diameter asteroid slam into it to trigger the eruption. :) Count Iblis (talk) 18:46, 16 May 2008 (UTC)[reply]

Masturbation

Hi,

If a woman masturbates continously, is it will be a problem on her menstrual period and is it will effect her body?—Preceding unsigned comment added by 202.124.160.212 (talk) 12:19, 14 May 2008 (UTC)[reply]

Yes, the splashing will soil the bed sheets.

Atlant (talk) 12:55, 14 May 2008 (UTC)[reply]

Replacing reply OP removed - please don't do that! I'm afraid we cannot provide medical advice. If you are concerned, you should consult a doctor. --Tango (talk) 14:28, 14 May 2008 (UTC)[reply]

What do you mean by 'continuously?' If you mean, without stopping at all, for several days, then she will suffer the normal effects from not sleeping, eating, or drinking. -FisherQueen (talk · contribs) 15:13, 14 May 2008 (UTC)[reply]

As FQ said, it depends what you mean by 'continously'. Presuming you simply mean regularly, according to [9] and [10] masturbation can be helpful in alleviating menstrual cramps. According to [11] 'solo' masturbation is not sufficiently associated with to maintainece of a fertile pattern of menstrual cycles, you need at least one sexual partner (male or female) for that (although coital intercourse is not necessary). My guess even if it isn't sufficient, a 'young' woman who masturbates regularly will still on average have higher fertility and a more regular menstrual cycle then someone who does not. According to [12] masturbation may or may not increase in the later luteal phase and may affect testosterone levels. It also appears woman has a higher desire for sex and an increase in sexual feelings in the midfollicular phase suggesting that there will likewise be a stronger desire to masturbate in this phase. Nil Einne (talk) 20:00, 14 May 2008 (UTC)[reply]

STEAM

WHEN WATER BOILS THERE IS STEAM. BUT, WHEN, WHAT TEMPERATURE IS STEAM CONSIDERED STEAM. IS IT ANYTHING PAST 212 DEG. OR STEAM PER USE REQUIRED? THANKS, DARRELL CHAPMAN —Preceding unsigned comment added by 69.44.236.100 (talk) 14:04, 14 May 2008 (UTC)[reply]

Please don't write in all capital letters, it is considered rude (and hard to read). Anyway, you may be interested in our articles on steam and superheating. While I cannot definitively answer what defines "steam" (perhaps a dictionary would be useful as well), I can conclusively state that "H₂O beyond 100°C" is insufficient, even ignoring atmospheric pressure. — Lomn 14:14, 14 May 2008 (UTC)[reply]

Steam is tiny water droplets suspended in air, this is distinct from water vapour. --Tango (talk) 14:26, 14 May 2008 (UTC)[reply]

There are a lot of different uses of terminology by both laypersons and experts; I'd be cautious about drawing such a sharp distinction. In engineering, steam is the gas that you get from boiling water; it is – or ought to be – pure water, containing very little air. At 1 atmosphere of pressure, you can make it by heating liquid water past 100°C and waiting until it has all boiled into the gas phase.

Live steam is steam that's held at a temperature above 100°C. All of the water remains in the gas phase. If you pull heat out of steam – as by running it down a long, uninsulated conduit – then its temperature will remain at 100°C, but some of the gas will condense into droplets of liquid water. Engineers will often discuss steam quality, where poor-quality steam contains a lot of water droplets. Steam turbines (for example) hate poor quality steam, as the liquid water droplets are murder on rapidly moving turbine blades.

In lay usage, the term 'steam' is often used to describe the cloud that appears above the spout of a kettle. There, it's a mixture of proper steam, water droplets, and air. (If you look closely at the space right above the spout of a hard-boiling kettle, you can usually see a small region where the cloud hasn't yet formed; that ought to be essentially live steam containing no water droplets or air.) TenOfAllTrades(talk) 15:15, 14 May 2008 (UTC)[reply]

Interesting. That's a very different definition than the one I know. Is it unique to engineers? --Tango (talk) 15:55, 14 May 2008 (UTC)[reply]

It's just a semantic definition based on "purity" of the gaseous H20. Such a quantitative measure would be useful if you were doing something with the steam (as driving a turbine). Nimur (talk) 16:27, 14 May 2008 (UTC)[reply]

I believe the answer needed was 100 deg C and the area between the steam cloud and the end of the kettle. In plants where steam is generated if you walk through steam pipeways you have to carry a broom handle with you. You wave it in front of you as you walk through. if and when a flange gasket gets a pin hole (leak), a pincle thin shot of -invisible- steam will shoot out. If you pass that broom handle through that it WILL slice through that stick and or arm. Thanks. —Preceding unsigned comment added by 69.44.236.100 (talk) 18:32, 14 May 2008 (UTC)[reply]

Coiling a wire is easy. Just carefully wrap it around a circular object - a thread spool, a pencil... if you want to go all out, you can purchase ferrite cores for a few cents each, and wrap it with a high-gauge ("thin") wire. Neodymium magnets are easy enough to get and are about as strong as you'll find. Your construction quality will affect how well you produce electric power; you may also want to think about mounting lots of magnets around the wheel to get a continuous flux. Alternatively, you could have one magnet which sweeps past the inductor once per wheel-revolution. This will generate a brief pulse of (high?) power; you could build a circuit which tries to spread that power over the full cycle until the next time the magnet comes back around. I doubt this will work very easily, since I think you will not get a whole lot of electric generation even with a good magnet. Nimur (talk) 16:32, 14 May 2008 (UTC)[reply]

If the point is to make the LED flash briefly as it passes a magnet fixed to the frame (or vice-versa), this should be a pretty easy circuit to engineer and a casual attempt at winding your own inductor will probbaly work. You should use two LEDs in antiparallel or place an ordinary silicon diode in antiparallel with the LED, though. Put a hundred turns on a steel bolt serving as a core, arrange the magnet to sweep by in close proximity, and see what happens. Try several magnet/bolt orientations. If nothing happens, add more turns to the coil until you get flashes.

Atlant (talk) 17:05, 14 May 2008 (UTC)[reply]

Theoretically The flux through an element of area perpendicular to the direction of magnetic field is given by the product of the magnetic field and the area element. you should get the best effect if you strung your wire along the wire rim. Practically I'd go with Atlant's idea. 71.236.23.111 (talk) 17:18, 14 May 2008 (UTC)[reply]

I noticed something that said that the voltage(?) would increase if the size of the circle were larger, but is this the case even if the loop is huge compared to the magnet? Would a wire wrapped around the rim of my wheel (I think this is what you are saying) really generate a current when wizzing by my little magnet attached to the fork?

Also, what is the best configuration for a given length of wire? Huge circle with fewer loops (say, around my wheel) or smaller circle with more loops? — Sam 17:45, 14 May 2008 (UTC)

Possibly you have misunderstood .111's idea (or maybe I have). 111 is not suggesting winding along the rim, rather, 111 is suggesting winding toroidally around the rim. A wire laid along the rim will not succeed in cutting any lines of magnetic flux from a fixed magnet attached to the frame. I think 111 has suggested themself that this is not very practical, you would need to wind over the face of the tyre which would rapidly destroy the wire on most road surfaces. Either that or wind underneath the tyre, but this would probably still result in the wire not lasting very long and would do nothing for tyre fit either. SpinningSpark 22:04, 14 May 2008 (UTC)[reply]

It should work fine, but you will be a sitting duck with no light when you stop, which would be very unsafe. The commercial version offers a backup so the light keeps flashing when you are stationary. I wonder if a coil (complete with iron core) from a doorbell/door buzzer would work as the pickup coil, with neodymiuym magnets attached to the spokes? Depending on how much electrical energy is supplied when the magnet passes the coil, you might feel an annoying pulsation in the pedal effort, as if the brakes were applied slightly. Normal LED bike lights run for a considerable time on very small batteries, so the energy per flash might be too slight to notice. But you never get something for nothing when extracting electrical power from human powered movement. Edison (talk) 22:37, 14 May 2008 (UTC)[reply]

Diabetes and the treatment of warts

(This is not a solicitation for medical advice. I’m asking the question out of intellectual curiosity. I have access to professional medical care, but I won’t bother my doctor with questions about medical conditions that I neither have nor have a reason to worry about.)

~~NO MEDICAL ADVICE - EVEN IF YOU SAY IT'S NOT A SOLICITATION FOR MEDICAL ADVICE !!~~

[In response to edit by 66.137.234.217:] The question is related to medicine, but there is no solicitation for medical advice. It does not ask for diagnosis, or treatment advice/recommendations. If you assume good faith, the question is not about the condition(s) of any particular person, named or otherwise, and whatever answer offered is not going to be relied upon. In what sense is the question a solicitation for medical advice?!

It's unfortunate that the first answer offered here was phrased in such a way to make the contributor look like he/she might be offering advice, but the wording those contributions does not determine whether the question is for medical advice.

If you're a position of authority to ban any and all questions related to medicine here, please just make the policy say so. If it is not the intent of Wikipedia to ban all questions that have anything to do with medicine, whether or not medical advice is sought, please don't be overzealous in labeling reasonable factual/scientific questions as solicitations for medical advice. Your unjustified assumption of bad faith, as well as your imputation of intent contrary to the apparent stated intent for no good reason, is offensive.

I’ve seen warnings on some over-the-counter medications for treating warts that the medications/treatments are not for people with diabetes. What’s the connection between diabetes and wart treatments? I assume that a doctor would have more options in treating a patient who suffers from both diabetes and warts. How may a doctor treat a warts patient who’s also diabetic? —Preceding unsigned comment added by 72.78.102.153 (talk) 16:21, 14 May 2008 (UTC)[reply]

People with diabetes mellitus are more likely to develop plantar warts which are caused by the human papilloma virus and these take longer to heal. I'm not sure on the physiology of why you can't use the treatments, however. Regards, CycloneNimrod^Talk? 18:55, 14 May 2008 (UTC)[reply]

The warning is to avoid being accused of causing or aggravating a diabetic foot ulcer. The salicyclic acid in the wart preparations can damage normal skin and some people with diabetes have reduced sensation and impaired circulation and healing. If the warning is understood and the preparation is used with care, it is not otherwise risky to diabetic feet. —Preceding unsigned comment added by 159.14.240.230 (talk) 21:03, 14 May 2008 (UTC)[reply]

Salicylic acid (the common ingredient in wart cures) is chemically very similar to acetyl-salicylic acid which is just aspirin. According to our article Aspirin: Aspirin is known to displace a number of drugs from protein binding sites in the blood, including the anti-diabetic drugs tolbutamide and chlorpropamide....I think it's safe to assume that displacing anti-diabetic drugs would be "A Bad Thing" for a diabetic. So yeah - it's quite likely that wart cures will screw with your diabetic medication - which could easily kill you stone dead. Given that there is an explicit warning on the wart treatment, I think we should regard advice to ignore it as an incredibly stupid thing to post in answer to a question here. Please ignore preceeding advice and consult a doctor. That's why we aren't allowed to give medical advice here - we screw it up all too often and in potentially dangerous ways. 66.137.234.217 (talk) 14:47, 17 May 2008 (UTC)[reply]

And thanks for providing another example of "screwed up" medical advice. Topical salicylic acid does not get absorbed, does not enter the bloodstream, and does not "screw with your diabetic medication"-- it simply burns whatever cells and skin it is painted on, whether warts or normal skin. The warning is also found in hot tubs and gadgets designed to burn off warts--- people with diabetes need to be careful about things that might damage the skin of their feet if they have any reduction of sensation. 159.14.240.230 (talk) 15:48, 18 May 2008 (UTC)[reply]

healthcare Infomatics

What is the meaning when information articles are characterized as "white page or white page article" ?Rlhandy (talk) 18:17, 14 May 2008 (UTC)rlhandy[reply]

Maybe it's a white paper? DMacks (talk) 19:20, 14 May 2008 (UTC)[reply]

My understanding of "white page" is that nothing has yet been decided or written and the writer is therefore free to make a construction from scratch. If the OP would give a link to where this was seen it would help to decide if this is the meaning. SpinningSpark 21:51, 14 May 2008 (UTC)[reply]

Avoidance of other people embarrassing themselves

Social anxiety can include avoiding social interaction out of a fear to embarrass oneself. But is there a technical term for (pathological) avoidance of situations where other people could potentially embarrass themselves? I've looked around this site, but I can't seem to find it. Social anxiety by proxy maybe? 82.210.125.161 (talk) 18:57, 14 May 2008 (UTC)[reply]

Agoraphobia is the closest thing I can come up with off the top of my head. Wisdom89 _{(_T / ^C)} 22:32, 14 May 2008 (UTC)[reply]

:-) Overanxious mother syndrome? I'd say you are on the right track with social anxiety. If avoidance is involved I'd go with "a type of social phobia". That's the closest I'd know, but I'm no expert. --71.236.23.111 (talk) 22:38, 14 May 2008 (UTC)[reply]

I would think that it would be related to a very high (overly high?) sense of empathy. Feeling anxious when other people are in terribly embarrassing situations (like many of us experience while watching embarrassing scenes in movies) is because of our ability to put ouselves into other people's shoes and feel like these things are happening to us, in the same way that watching someone in pain can be exceedingly painful. — Sam 13:19, 15 May 2008 (UTC) —Preceding unsigned comment added by 63.138.152.238 (talk)

Psychological projection might have something interesting. But still no definite term.Lisa4edit (talk) 13:58, 15 May 2008 (UTC)[reply]

Does stars have that divine light , the reason for creation? Which guides humanity and other creatures? if so, where are they channelized?

I was reading a book, which says if we can attain oneness, we can attune with the nature around.. as well as with the oness of other creatures.is this oness..or the divine light..or the golden light..suppossed to come from one channel ( we call Heaven)-& perceived by only those , of the likes - Jesus, Hindu Gods - Shiva, Durga, Allah?--who have same commn star..to guide & protect them? also does this energy frm the light of stars affect ur lives, which can inturn mark the change in century? Trekkersdelight (talk) 21:26, 14 May 2008 (UTC)[reply]

Doesn't really seem to be a science question. Try the Humanities Desk. SpinningSpark 21:46, 14 May 2008 (UTC)[reply]

The common star for all these is the sun, and this surely does affect our lives. But the basis of this book does not sound like science, so this is probably not the desk to ask this question or make your statement. Stars do not mark centuries, these are a human creation as part of the calendar. Graeme Bartlett (talk) 21:47, 14 May 2008 (UTC)[reply]

Stars are often "channeled" or "channelized" here --Bmk (talk) 01:48, 15 May 2008 (UTC)[reply]

If oneness is attained how could there be stars, light, channels, perception, protection, guidance, lives, centuries, etc? If these differences remain, it's not oneness. Pfly (talk) 06:35, 15 May 2008 (UTC)[reply]

Tapeworms as a weight-loss aid?

Does WP have an article on this, as a matter on interest? Occasionally, I have read about people intentionally cultivating their own internal parasite(s), the thinking being that healthy, well-fed worm = slimmer human. Don't know if it actually works or not (I suspect that the effect is minimal) but I would like to read more about it. --Kurt Shaped Box (talk) 22:27, 14 May 2008 (UTC)[reply]

The pathology section of the Tapeworm does mention weight-loss as a possible symptom, but there's not much information. I think if you read the other symptoms you'll agree that self-infecting with Tapeworms is a terrible, terrible idea. And I might mention that I think vitamin deficiency is more likely than weight-loss. Ugh. --Bmk (talk) 00:16, 15 May 2008 (UTC)[reply]

On the other hand, is keeping a pet tapeworm in your innards particularly more extreme/nasty in terms of unwanted effects than some of the other methods that people try in an attempt to control their weight - Olestra, amphetamines, Liposuction, Stomach stapling, various diet pills etc.? --Kurt Shaped Box (talk) 00:29, 15 May 2008 (UTC)[reply]

I would definitely prefer getting Liposuction over self-infecting myself with a tapeworm *spine shivers* 76.196.10.3 (talk) 01:22, 15 May 2008 (UTC)[reply]

That's a fair point KSB, but I still would rather have surgery or some other treatment than tapeworms, even if they worked well - they give me the creeps. --Bmk (talk) 01:45, 15 May 2008 (UTC)[reply]

Agreed. Plus you may end up actually gaining weight, because your body will try to compensate for the lack in nutrients by making you eat more. --71.236.23.111 (talk) 02:04, 15 May 2008 (UTC)[reply]

worms can also help against asthma :) Count Iblis (talk) 02:29, 15 May 2008 (UTC)[reply]

Just a rumour? Maria Callas' radical weight loss raised speculations, among them, tape worm. ; ) Julia Rossi (talk) 11:03, 15 May 2008 (UTC)[reply]

That's a great article idea, we should have at least a well-done section about it. Mac Davis (talk) 17:17, 15 May 2008 (UTC)[reply]

I'm having a deja vu moment here, didn't I just ask a question about this recently ? I believe I mentioned that other seemingly disgusting creepy crawlies are sometimes used medically, like maggots to eat away gangrene and leeches to restore blood flow after finger reattachment surgery. Our tapeworm article says that, while many nasty effects can happen from tapeworms, they rarely do: "According to Intestinal Cestodes, authors Craig, and Ito 2007 suggest that the effects of this gut dwelling Cestodes are usually very minimal". This compares with the very common and disgusting side effects, such as anal leakage, associated with commercial weight loss formulae like Alli. StuRat (talk) 11:45, 16 May 2008 (UTC)[reply]

One thing I could imagine regularly occurring amongst tapeworm aficionados, which might lessen the effectiveness of the method is the "I've got a worm inside me, so I can get away with eating more now!" effect. --Kurt Shaped Box (talk) 12:18, 16 May 2008 (UTC)[reply]

Yes, but people who are candidates for bariatric surgery have no self-control to begin with, that's why they are morbidly obese. StuRat (talk) 23:53, 16 May 2008 (UTC)[reply]

I actually saw a jar of tapeworms in a museum of pharmacy products from the early 1900s. There's a picture of an advert here. They were sold as a weight-loss aid. ~Amatulić (talk) 21:03, 19 May 2008 (UTC)[reply]

Trees in paper

If you have 100 cubic feet of wood with whatever density most trees have, how many 8.5" x 11" pieces of paper can you get. Inversely, how much wood goes into making 100 sheets of paper? Not homework, by the way. Thanks, schyler (talk) 23:16, 14 May 2008 (UTC)[reply]

The first problem is determining how much of the tree's lignum can be converted to cellulose. Figures differ depending on the method applied and who states the figures for what purpose.

Figures on cellulose content I've found range from 30% [13] to 50-55 % of a tree’s volume [14]. Wood pulp describes various methods for turning wood into pulp from which cellulose can be produced. Each method offers a distinct rate of efficiency with trade offs in quality, energy use and water pollution. So there is no direct answer. Maybe someone else can narrow it down some. --71.236.23.111 (talk) 02:00, 15 May 2008 (UTC)[reply]

The number of sheets of paper you can make will depend highly on the thickness of the paper. The amount of wood needed for a 100 sheets of tissue-thin paper (say for a bible) will be different than that for 100 sheets of thick letterhead. - You may want to look at the Papermaking article. -- 128.104.112.147 (talk) 23:06, 15 May 2008 (UTC)[reply]

subquestion: how much wood would a woodchuck chuck if a wood chuck could chuck wood? --Shaggorama (talk) 07:30, 19 May 2008 (UTC)[reply]