Wikipedia:Reference desk/Science

Welcome to the science section
of the Wikipedia reference desk.

skip to bottom

Select a section:

• Computing
• Entertainment
• Humanities
• Language
• Mathematics
• Science
• Miscellaneous
• Archives

Want a faster answer?

Main page: Help searching Wikipedia

   

How can I get my question answered?

• Select the section of the desk that best fits the general topic of your question (see the navigation column to the right).
• Post your question to only one section, providing a short header that gives the topic of your question.
• Type '~~~~' (that is, four tilde characters) at the end – this signs and dates your contribution so we know who wrote what and when.
• Don't post personal contact information – it will be removed. Any answers will be provided here.
• Please be as specific as possible, and include all relevant context – the usefulness of answers may depend on the context.
• Note:
  • We don't answer (and may remove) questions that require medical diagnosis or legal advice.
  • We don't answer requests for opinions, predictions or debate.
  • We don't do your homework for you, though we'll help you past the stuck point.
  • We don't conduct original research or provide a free source of ideas, but we'll help you find information you need.

Ready? Ask a new question!

How do I answer a question?

Main page: Wikipedia:Reference desk/Guidelines

• The best answers address the question directly, and back up facts with wikilinks and links to sources. Do not edit others' comments and do not give any medical or legal advice.

See also:

• Teahouse
• Help desk
• Village pump
• Help manual

December 26

Is galactic red shift not really the Big Bang singularity’s time-dilating effect?

Long ago (in high school) I wanted to be an astrophysicist before circumstances forced me into engineering, but I try to track some of the issues from a layman’s viewpoint. If light heading into a gravity well is blue-shifted (just read this on Wikipedia), and that which is coming out is red-shifted, what else can one make of the red-shift of light from distant galaxies apart from conjecturing an expanding Universe alone? ‘Long ago’ and ‘far away’ mean the same thing, yes? This means that for all practical purposes the Universe from all standpoints is surrounded by its Beginning, which is the Singularity that preceded the Big Bang. Could it not be that the red-shift we see in light from so-called receding galaxies is rather due to the fact that the light is climbing out of a gravity well at whose bottom lies the Singularity? I don’t know what the relation between red-shift and gravitational intensity is, whether it follows the R-squared rule of gravity or not, but I suspect that the Hubble Constant is an outcome of the interplay of this relation and the effects of ‘Singularity Gravity’ (to coin a phrase) on space-time. It is not really so much that the distant galaxies are receding faster and faster as that WE are much farther from the Centre than they are. After all, they are younger than we are as they are closer to the centre. The red-shift we see is ours more than it is theirs. Our spectrometers have departed farther from what they should have been nearer the time of the Big Bang. Of course we are at this distance because the Universe is expanding, but need it be in an accelerated fashion? Coming to think of it, the speed of light must have been changing all the time since the Big Bang – in all neighbourhoods. Either that, or what we now call a metre (meter) has been stretching out as we moved away from the Centre of the Universe….. I have no means of presenting my thoughts in the form of a question as such. I would appreciate a critique of my reasoning so I can see where I can reorient myself. Capping it all is the vexing problem for me of measuring distances to objects that are really in the past. Where are they now? Can we say that because they are still within the light cone then they do exist as we see them until they go over the cosmic event horizon back into the Big Bang black hole? Havanyani (talk) 01:37, 26 December 2009 (UTC)

I cannot answer all of your questions, but why do you think the initial "centre" of the big bang was a black hole? Standard physics expects the speed of light to be constant, but there is a varying speed of light theory that has not acquired much acceptance from the scientific community. Redshift can also be seen in a galaxy within the side that is rotating towards us, but this effect is only noticeable in nearby galaxies. If the universe is infinite, one idea is that the "surface" of the "outside" would have no curve, meaning the universe is flat. However, there's another idea that it could have a negative curve and be "saddle-shaped". This would allow for the "centre" of the big bang to line the "outside" of the curve, but otherwise there is no centre of the universe, and the big bang as an object cannot be located. So there is no "edge" of space, as the visible "horizon" of the visible universe is not the limit of the actual universe itself, although we cannot see beyond that barrier. I'll let someone else answer this before I get too confusing. ~AH1^(TCU) 02:29, 26 December 2009 (UTC)

Not sure I can follow the OP's train of thought, but one thing the OP seems to be grasping at is the fact that gravitational redshift is indistinguisible from motional redshift; that is we cannot tell the difference between gravitational acceleration and other forms of acceleration. Einstein himself called this the Equivalence principle, and it was part of general relativity, which actually deals with MOST of what the OP is talking about. --Jayron32 04:48, 26 December 2009 (UTC)

The act of Sex

Is there a religion in which it is believed and practiced that the act of sex between a male and a female is sacred? 71.100.6.153 (talk) 01:44, 26 December 2009 (UTC)

Quite a few of them, in fact. The LDS Church teaches that sex should only occur between a legally married husband and wife, and that the powers of procreation are sacred and a gift of God. I know many other Christian churches also teach something similar. ···日本穣^? · 投稿 · Talk to Nihonjoe 02:40, 26 December 2009 (UTC)

To take it to an extreme, there have always been cults in the Western world that have had sacred sex. Consider the very cultish Children of God, which openly used prostitution to proselytize new members. See also Sacred prostitution which covers MANY such movements dating back thousands of years through many cultures. --Jayron32 04:39, 26 December 2009 (UTC)

I guess you mean Flirty Fishing, while some of their other (former?) practices involving children are disgusting, I personally find Children of God (cult)#Loving Jesus funny particularly the proscription for males Nil Einne (talk) 08:09, 26 December 2009 (UTC)

"TFI continues to stress the imminent Second Coming of Christ"... Nimur (talk) 12:56, 26 December 2009 (UTC)

If you are are willing to add the word "married" to your question, then Judaism believes so. In fact it is considered one of the holiest acts, because it is the only one that can cause the spiritual (a soul) to be embedded in the physical (the body). Nothing else can do that. (And just like it can be the most holy, it can also be the most un-holy.) Ariel. (talk) 00:26, 27 December 2009 (UTC)

Interesting... perhaps then that is how I should have framed the question, i.e., what criteria makes the act of sex either holy or unholy in various religions? 71.100.6.153 (talk) 01:59, 27 December 2009 (UTC)

Cult leaders often tell their female followers that. 67.243.1.21 (talk) 03:28, 27 December 2009 (UTC)

The sexual act or "Great Rite" is the central sacrament in Wicca and allied neo-Pagan Paths. Usually it is performed only symbolically (by placing the black-handled knife or 'athame' into the cup or chalice), but on special occasions it may also be performed in actuality by the High Priest and High Priestess of the Circle (aka "coven") who are presumed to invoke the God and Goddess respectively within themselves while doing so (and who are usually a married/handfasted couple). Some Circles' initiation of new members (usually after at least a year of probationary study) includes having them perform the Great Rite with the High Priest or High Priestess as appropriate, but this may be done in private with only the two participants knowing if the performance was symbolic or actual. Note that Wiccan ceremonies do not involve all of the Circle's members (all of whom are themselves Priests/Priestesses, hence the 'High' used for the Ceremony's or Circle's leaders) having sex, and the tradition of some Circles of working 'skyclad' or nude has no sexual connotations.

Note also that all of this brief description is a generalization, since every Circle follows and develops its own Path, so some details may not be applicable to a given Circle. 87.81.230.195 (talk) 03:06, 29 December 2009 (UTC)

Mystery red plant between Incheon International and Seoul, Korea

I've been wondering for years about what this plant might be, but I've never found anything about it. I found a picture of it here, but it's not a closeup picture. It grows all over in the sandy marshes between Incheon International Airport and Seoul. Any help in identifying it is appreciated. ···日本穣^? · 投稿 · Talk to Nihonjoe 02:37, 26 December 2009 (UTC)

That's a beautiful picture! Can you discribe the plant a little, height, flower type, etc.? Gandydancer (talk) 04:17, 26 December 2009 (UTC)

I wish I could as that would make it easier to identify. As it is, I've only seen it as close as you can see in the picture, and I've wondered about it for almost nine years now. ···日本穣^? · 投稿 · Talk to Nihonjoe 04:55, 26 December 2009 (UTC)

It sounds like this is something very dear to your heart and I hope you can find the name. Are you from Korea? I'm pretty familiar with most of the plants in the US and the only one here that I know to grow in such profusion in sand at ocean's edge is "ice plant", but it is a succulent and you mentioned marshland. It is here: http://en.wikipedia.org/wiki/Aizoaceae Gandydancer (talk) 05:39, 26 December 2009 (UTC)

Not really dear to my heart, just piqued curiosity. When I can't figure something out, it just bugs me. No, I'm not from Korea, though I am interested in many things about Korea. As for it being marshland, I was just guessing that's what it was since it's right by the coast. Does that plant turn red at any time of the year? ···日本穣^? · 投稿 · Talk to Nihonjoe 05:55, 26 December 2009 (UTC)

I've never been to Korea and from the picture it is hard to tell if that is sand dunes or marsh land. If it is sand dunes, a succulent would be a good guess. Yes, in bloom it would look like the picture. Gandydancer (talk) 06:07, 26 December 2009 (UTC)

It could be salicornia. Here's a photo of the salt marshes near where I live that shows the reddish color of salicornia in the winter [1].--Eriastrum (talk) 23:31, 26 December 2009 (UTC)

I think you nailed it! Just curious, where do you live? Gandydancer (talk) 04:30, 27 December 2009 (UTC)

At a guess in or near Morro Bay, California? Nil Einne (talk) 10:10, 27 December 2009 (UTC)

The only problem being that these plants are red in summer (late July, early August). ···日本穣^? · 投稿 · Talk to Nihonjoe 19:24, 27 December 2009 (UTC)

I do indeed live near Morro Bay on the central coast of California. The salicornia does start to turn reddish in the late summer and fall; it is reddish throughout the cooler months.--Eriastrum (talk) 20:48, 27 December 2009 (UTC)

What causes our windup toy to spark, and what are sparks?

My grandson got a windup toy for Christmas today. You wind it up and that makes a bar rotate over a flat, round circular surface. Two small spokes hang down from the bar and rapidly circle the flat plate producing sparks. We are guessing that the two spokes are flints and that the circle, which looks like sandpaper, is a steel sandpaper. Then we got into a discussion about what was needed to produce...sparks? (we weren't sure exactly what we were trying to "prove"...). At any rate, we came up with oxygen, heat (from friction), and a 3rd thing, and I'll be darned if I can remember what it was. Any thoughts on this process would be most welcome. We did wonder if there is a little heat in the sparks, and we guess that there is, since I know that they can be used to start tinder.

The discussion went on to "exactly what is a spark?", and is this process similar to the (I think) electron transfer that causes the little shocks that one occasionally experiences in a dry atmosphere when rubbing two things together. Is there "heat" in those shocks?

Sorry for the very poor explanation - my physics knowledge is very limited. Gandydancer (talk) 05:06, 26 December 2009 (UTC)

Oxygen, heat (source of ignition) and.....FUEL (something to 'burn', though oxidation may be technically more accurate), See also Fire. Your flint and 'sandpaper' hypothesis sounds very likely.
A spark (from a fire or flint) would be a tiny piece of fuel that is in fact burning (educated guess only!). In you second para ("little shocks"), you are referring to static electricity, not the same as the toy sparks. Though static is same as the 'sparks' from a 'trigger' type gaslighter. see Piezoelectricity. (both electricity, though produced by different processes)
Heat?, yes there would have to be though it occurs so quickly you can't feel it. Lightning is also static electricity can be extemely hot, though only for perhaps microseconds (thousandths of a second) --220.101.28.25 (talk) 05:37, 26 December 2009 (UTC)

More accurate definition of Spark "A spark is a small airborne ember or particle of red-hot matter." ie. doesn't have to be actually burning--220.101.28.25 (talk) 05:48, 26 December 2009 (UTC)

... consequently, oxygen is not needed for sparks to form. However, sparks in an oxygen environment can result in flame. Nimur (talk) 13:01, 26 December 2009 (UTC)

Yes, so it appears, though usually oxygen would be present. Most sparks seen would be coming from a fire, though in this case (original question) they are produced from friction, similar to a grinder. Be interesting to see a grinder used in a nil oxygen(vacuum?) environment See also Ember, which may put a slightly different slant on it. --220.101.28.25 (talk) 14:00, 26 December 2009 (UTC)

Some delicate machining work takes place in a nitrogen- or argon-flooded work area, to minimize chance of flame. The metal flakes kicked out during machining do still glow (from blackbody radiation, which does not require flame). Systems which will eventually store pure (~100%) oxygen or other strong oxidizers are specially checked for metal burrs, flakes, or any other tiny metal particles, because the ability to spark just by shaking around these tiny flakes (e.g. steel-on-steel collisions or friction resulting in sparks) may result in fire, if the atmosphere is very highly oxidizing. The fuel source can be the steel particle itself, which can burn in the presence of oxygen. This cleaning procedure, along with other cleaning to remove any flammable fluids or hydrocarbon lubricants, is part of what rates a system as "oxygen clean" - i.e., reduces the risk of spark ignition and flame, when oxygen is added. The OP's discussion of "a 3rd thing" is in reference to the Fire triangle. Sparks are the ignition, not the result, of fire. Only in unusual cases (such as those I mentioned) can the sparking material itself also be the fuel for the fire. Again, keep in mind that the only things necessary for fire are fuel, oxidizer, and ignition - normally, we take the oxidizer for granted, because we are in Earth's atmosphere. But flame can still exist, for example, in underwater welding or in the vacuum of space, if we bring the oxidizer with us. Hypergolic fuels provide chemical self-ignition, and combust without any spark to ignite them. Nimur (talk) 14:37, 26 December 2009 (UTC)

Sparks can certainly be the result of fire. I once burned an aluminium lamp socket, by accidentally shorting it. It made a fountain of very very bright white sparks about 6 feet high. A spark is burning metal, so it's fuel and ignition at the same time. (A spark can also be electrical.) Ariel. (talk) 00:40, 27 December 2009 (UTC)

I am reading everything and thank you! I have looked at the links provided and looked at spark plugs and flintlocks as well. I have begun to rule some things out, however I am still far from an explanation. Certainly one problem is my problem with a poor understanding of physics. As time permits I will try to come to an understanding of where I am at. Again, thanks. Gandydancer (talk) 18:15, 26 December 2009 (UTC)

There are two kinds of sparks. One is electrical, like a static shock, or a spark plug. The other is burning metal. Electrical sparks are blue (in normal air anyway), and metal burning is various colors, including blue, but usually red or white.

Contrary to assumptions, when you rub metal in a grinder, it is not the heat of friction that causes the sparks, but rather tiny pieces of metal that break off, and burn in air. Most metals are flammable. Aluminium is extremely flammable, and iron too - they are just pretty hard to ignite. You can see iron burn, by using fine steel wool - you can light it with a match. And aluminium is burned in the space shuttle. Both simply need a lot of air to burn, and by making tiny pieces you have a large amount of air relative to the surface area of the metal, and it burns.

The reason iron does not normally ignite, is that when the surface rusts (aka burns) it releases some heat, but the heat is absorbed in the mass of the metal, and it never gets hot enough to get going. Aluminium protects itself with a surface layer of alumina, that is very hard, and seals the metal from any additional air. Ariel. (talk) 00:36, 27 December 2009 (UTC)

I have nothing to add to Ariel's excellent answer but my name compels me to contribute to this thread, so I will confine myself to complaining that we seem to be lacking an article here. Spark is a disambiguation page and has no article listed that really covers this meaning, ember really refers to wood or coal fires. There is, however, spark testing which has a section that explains about metal burning (see spark testing#Compressed air method). SpinningSpark 01:37, 27 December 2009 (UTC)

Arie, you say "Contrary to assumptions, when you rub metal in a grinder, it is not the heat of friction that causes the sparks, but rather tiny pieces of metal that break off, and burn in air." So in our toy, the flints move over the metalic surface flicking off tiny chips of metal (the fuel), and in the presence of ozygen they will burn (oxidize). And the friction is needed to heat the metal to its burning point? Say, thanks for that spark test page! I'll check out the toy tomorrow and see if we can ID the metal. I think the kids will enjoy that, and of course I will as well. Gandydancer (talk) 04:00, 27 December 2009 (UTC)

Coughing while asleep?

Last time that I was ill, I had a cough that could be heard through the (admittedly, rather thin) wall and door for my bedroom. Others in the house reported that I sometimes coughed in the middle of the night, even on nights during which I had no memory of waking up. Is it possible to cough while asleep, or is it more likely that I was awake for such a short time that I didn't remember it in the morning? Nyttend (talk) 05:50, 26 December 2009 (UTC)

I don't see why not. Sleep covers a wide range of neurological states, some much deeper than others. People certainly move while asleep (tossing and turning, for example), so I don't see why in some of the lighter stages of sleep you would not also cough if your airway was irritated. --Jayron32 06:29, 26 December 2009 (UTC)

Both sound equally likely to me. You can do a lot that you don't remember during brief waking periods at night. Vimescarrot (talk) 11:49, 26 December 2009 (UTC)

Also, this could explain you being more tired in the morning due to lack of REM sleep if you're only sleeping lightly all night due to the coughing. ···日本穣^? · 投稿 · Talk to Nihonjoe 16:49, 26 December 2009 (UTC)

what is the evolutionary advantage of appreciating natural beauty?

It is almost instinctive to like a vista, grand views, rushing rivers, the smell of flowers, green leaves... well maybe it's advantageous to prefer forests over deserts, but even humans find deserts beautiful sometimes. Ignoring the issue of appreciating the beauty of the opposite sex, why would an appreciation for beauty evolve at all? John Riemann Soong (talk) 06:06, 26 December 2009 (UTC)

Our article Aesthetics is related and will be of interest, though it is a philosophy article and not an evolutionary biology article. Comet Tuttle (talk) 06:43, 26 December 2009 (UTC)

I have a hypothesis that it's due to the brain getting new patterns, because obviously beauty can go stale. --Ayacop (talk) 07:49, 26 December 2009 (UTC)

I am a person that does a fair bit of natural beauty hunting and I'm not sure that appreciation for natural beauty is an evolved trait at all. One could easily argue that it is the result of environment rather than hereditary. If it is evolved then it might not have been caused by direct evolutionary pressure but as a by product of something else. Noodle snacks (talk) 08:35, 26 December 2009 (UTC)

But what would the trait piggyback on? John Riemann Soong (talk) 09:14, 26 December 2009 (UTC)

I don't think that hard science can explain it. It seems to me that one must go into the realm of Noetic Science http://en.wikipedia.org/wiki/Noetic_sciences for an explanation, but most people are not willing to go there. Gandydancer (talk) 18:08, 26 December 2009 (UTC)

The visual beauty you refer to utilizes the sense of sight in a special way. The satisfaction one experiences may be not so much linked to the external stimuli but to the sensation of the functioning of one's visual apparatus. Sight is highly developed in humans in various ways. Expansive vistas of nature illuminated by sunlight allow for a full exploitation of our visual capabilities. This situation might be compared to having a car that can go 400 mph and finally finding a place to utilize that ability. I don't know why there would be pleasure associated with viewing these vistas. But it may be a pleasure just relative to settings that use a far narrower range of our abilities. I doubt if people who live amidst a breathtaking setting are constantly appreciating their view, at least not in a way that they are keenly aware of. Bus stop (talk) 00:04, 27 December 2009 (UTC)

The question carries an implicit assumption that perception of beauty is a function that gives a survival advantage, like having an opposable thumb. IMHO perception of beauty is a survival confirmation only.Cuddlyable3 (talk) 00:13, 27 December 2009 (UTC)

Some things we find beautiful are beneficial things - fertile rolling green hillsides, for example, are likely to contain lots of good food and shelter. I'm not sure how relevant that actually is, though, since it doesn't universally apply. Barren wildernesses are often considered beautiful, and I would think they were best avoided. --Tango (talk) 00:24, 27 December 2009 (UTC)

I believe I have heard someone, I think in National Geographic Magazine, of about a year ago, describe deserts as the most beautiful of places. Bus stop (talk) 00:28, 27 December 2009 (UTC)

Why does wanking feel good? I'm pretty sure our consciousness combined with some formerly advantageous traits can have spurious results. —Preceding unsigned comment added by 92.17.229.48 (talk) 00:52, 27 December 2009 (UTC)

Even fish can have fetishes (sticklebacks I think). 67.243.1.21 (talk) 03:26, 27 December 2009 (UTC)

Also, on the same topic, if one is indoors for a day or two or three, and then one emerges into a not at all spectacular environment — it may look beautiful. If it were merely an urban or suburban setting of no noteworthy natural vistas, but merely say, a sunny morning, after a rain — the glistening objects, however banal, could be of breathtaking beauty. This once again shows that the appreciation of natural beauty is a relative thing. Compared to being in a dimly lit indoor space for three days, any kind of outdoor space in sunshine would be aesthetically pleasing. This also illustrates that we get used to the breathtaking aesthetics of nature, and fail to see it. But I think it has to do with the full utilization of our senses. In a dimly lit room the eyes have limited opportunity to do all that they are capable of doing. This is just conjecture, or original research. Bus stop (talk) 19:01, 27 December 2009 (UTC)

Bear in mind that perceptions of visual beauty are not necessarily even cultural, let alone human, universals, nor are they fixed in time within cultures. For example, most modern Europeans find the vistas of the Alps majestic and uplifting, but before the 18th century Romantic movement they were considered frightening and depressing. 87.81.230.195 (talk) 02:30, 29 December 2009 (UTC)

does MSG change taste with pH?

Other than the change in taste caused by vinegar, etc. Does glutamate that is +1 or at the pI taste differently than glutamate at -1? Would -2 glutamate (e.g. I add baking soda to MSG) smell like fish? John Riemann Soong (talk) 09:18, 26 December 2009 (UTC)

Help someone? I really can't find it in the literature, and otherwise I think I'll end up experimenting to find out. (Though I don't think I can add enough baking soda to get to deprotonate the amino group....) John Riemann Soong (talk) 07:08, 27 December 2009 (UTC)

Problem with Japanese appliances in European plugs

Hi, I'm trying to charge my Japanese Nintendo DSi (for the plane ride home of course!) in Ireland, and I'm having trouble. I have the proper prong converter and a voltage converter that works for Canadian appliances, and every other Japanese piece of electronics that I've brought with me (though admittedly I don't have anything as heavy duty as the DS), but the DS is non-responsive. At most I get a single flicker of the charging light when I plug it in, but it won't be charged at all after an hour plugged in. The DS works (for a couple of seconds before the battery goes flat) so I'm convinced nothing's been burned out, and I charged it fine just 3 days ago (in Japan), so I'm lost as to why I wouldn't be able to charge it here. Does anybody know of any reason why I might be having this problem? Thanks! 83.71.33.178 (talk) 09:31, 26 December 2009 (UTC)

It's not really possible to diagnose your problem without having the equipment in front of me to test but here are some possibilities. First off, without checking with a meter, you cannot be sure that your converter is providing the right voltage. Many charger circuits nowadays are "universal"; that is, they will accept a wide range of input voltages. They will consequently still charge even if you have not provided the voltage you think you have. If your DS is not "universal" the difference is explained. A more likely explanation is that there is a fault with the connection cable between voltage converter and DS (do you use the same cable for any other piece of equipment?). The brief flicker of the charging light would seem to indicate a fault, either with the cable, or worse from your point of view, with the circuitry in the DS. That kind of brief flicker is often indicative of something that has gone open circuit, you still get a brief burst of current through capacitive coupling when first connected. SpinningSpark 10:48, 26 December 2009 (UTC)

Yeah, the brief flicker was suspicious to me too, so I checked with the exact same combination of voltage converter/prongs on some other electronics and it worked fine, so I figure it must be something on the DS, or the AC adapter for the DS that was aborting the connection or just failing for some reason. The DS is still definitely in working order though. The DS and the AC adapter are not universal (no built in converter), the AC adapter says it's for 100V/110V, which should work fine with the Canadian voltage converter, usually built for ranges around 120V, though it might be designed to be more sensitive so as to protect the electronics, I don't know. 83.71.33.178 (talk) 11:25, 26 December 2009 (UTC)

Usually, small/cheap converters only convert the voltage and not the frequency - and some devices care about that which is a common cause for problems. Ireland is 220v/50Hz - but Japan is a mess with some places being 110v/50Hz and others 110v/60Hz - which usually means that Japanese-made equipment is tolerant of frequency differences. But it's really hard to know how to solve your problem without more information.

My best advice is to buy an in-car charger for the DS (they are pretty cheap) and charge it up from the 12v outlet on a car. Of course this assumes you have access to a car. The good thing about this approach is that (a) it's definitely going to work - all cars everywhere work at 12volts and (b) you'll be able to use the car charger when you get back to Japan, so the money you spend isn't wasted on a gadget you'll never use again. If you don't have access to a car - you might look to see if there is a USB charger for the DS that would let you charge it from a computer...I guess you have access to a computer because you are reading this reply on one! SteveBaker (talk) 14:17, 26 December 2009 (UTC)

Statements that begin "All cars everywhere..." are usually exaggerations. Austin 10 1932-1933, Wolseley Eight 1946-1948, Volvo PV444/544 1947-1961, Renault Dauphine 1956-1968, DAF 33 1969-1971, and Citroen 2CV 1948-1990 1966 are all cars that are running somewhere on 6-volt batteries. Cuddlyable3 (talk) 21:04, 26 December 2009 (UTC)

This is true - and remember there are still quite a few positive-earth cars on the road, albeit of a similar vintage to those mentioned. A somewhat greater risk these days is finding that the car you want to use as a power source doesn't have a cigar lighter... Tevildo (talk) 21:28, 26 December 2009 (UTC)

Oh good grief. Firstly, it you're going to be pedantic - at least get it right: the 2CV switched over to 12volt batteries in 1966 (I have restored a '68 2CV and I know this for a fact). So perhaps I should have said "all cars less than ~38 years old"...except that the virtual impossibility of buying things like headlamp bulbs and car radios for 6v systems means that a very large proportion of positive ground and 6volt cars that are still on the road after 40 years have been retro-fitted with negative-earth and 12volt batteries. Only the most fanatical car restorer would try to keep such antiques on the road with their original electrical systems. Now ask yourself whether ANY of those 40 year old 6v cars have cigarette lighters with modern connectors - and whether the negative-earth ones are wired such that just about anything you'd plug into it would blow up? (The couple of car nuts who I know who have their Mini's still wired up with negative earth evidently wired up their after-market accessory sockets the 'conventional' way because I know they use them to charge their walkie-talkie's). The answer I gave is very nearly 100% perfect. This kind of pedantry on the RD is getting really tiresome guys. Sheesh! SteveBaker (talk) 04:02, 28 December 2009 (UTC)

Thank you SteveBaker for giving the date when the Citroen 2CV changed from 6 to 12 volt. I have struck and corrected my 1990 date which was for the end of production of the 12volt car. I believe the 6volt runs of the other cars are correct. Parts are available to maintain all these cars and it only takes one diligent maintainer of such a car to invalidate your exaggeration. That's a good question about the availability of cigarette lighters on these 6V cars. Volvo Owners Club write about cigar lighters on Volvo taxis 1950 - 1958. The article Cigar lighter receptacle describes a 6volt version. Philips made a 6volt radio that fits the DAF 33. My understanding is that after the early 70s all mass produced British cars have been delivered with negative earth. In cases where the cigar lighter socket has an insulated surround there seems to be no compelling rule about which polarity its wiring should be. I would expect the center to be +ve and much in-vehicle electronic equipment to survive a reverse 12volt connection, at least if the supply has a 5 amp fuse. The standard for Wikipedia is not being near 100% perfect, it is verifiability.Cuddlyable3 (talk) 02:49, 29 December 2009 (UTC)

Or you could go buy a USB charger and do it that way, as you've obviously got access to a computer! 61.189.63.130 (talk) 00:40, 27 December 2009 (UTC)

(I already said that). SteveBaker (talk) 04:02, 28 December 2009 (UTC)

Steve, there was no need for that comment, it is superfluous for those that noticed you already said it and saying it again is useful for those that did not. You have done the very thing you are complaining about to me in the past, so please don't get touchy about it when it happens to you. SpinningSpark 17:11, 29 December 2009 (UTC)

The behavioral guideline WP:NOOB is helpful here. User 61.189.63.130 may not have posted much before and SteveBaker may take comfort in the adage by Charles Caleb Colton that "Imitation is the sincerest (form) of flattery". I hereby confess Mea culpa that it was my sin that drove SteveBaker to exclaim in piteous cries "Oh good grief...Sheesh!" at 02:49, 29 December 2009. SpinningSpark, he has suffered enough already so please be gentle. Cuddlyable3 (talk) 23:30, 29 December 2009 (UTC)

December 27

Male involvement in pornography

1) How do females who work in the realm of pornography maintain a non-platonic relationship with a male counterpart while being involved in pornography?

2) How do males get involved in pornography-related careers? Are there aesthetic criteria they must meet, or does any guy get in? Both points seem odd to me when I think about it. DRosenbach ^{(Talk | Contribs)} 03:09, 27 December 2009 (UTC)

By "non-platonic" does that mean the opposite of Platonic love, as this linked-to article would define it? Bus stop (talk) 03:20, 27 December 2009 (UTC)

Well, I figure that there might be a pornographic actress who is married and tries to become pregnant with her husband and work might 'get in the way.' DRosenbach ^{(Talk | Contribs)} 05:24, 27 December 2009 (UTC)

Oh, I see. I misunderstood. I was thinking the non-platonic relationship being referred to was with the male porn star. You should have referred to the male as a "significant other" or some such locution. Or I should have thought about it more. Bus stop (talk) 05:45, 27 December 2009 (UTC)

I think the solution is two-fold: 1. People in porn tend to be young, and 2. Most males or females might be willing to forgo their normal sense of jealousy for the bragging rights (and supposed sexual benefits) of dating a porn star. It's also presumably possible that the type of personality that would pursue a career in the porn industry is one that would tend toward a single lifestyle. And, for what it's worth, a fair portion of porn doesn't actually involve significant penetrative sex. ~ Amory (u • t • c) 13:28, 27 December 2009 (UTC)

I've seen two documentaries on the pornography business in general. Any woman can get in. Just like any acting, it is mostly just luck to become a star. As for men, both documentaries stated the same thing. Men begin in gay movies and, if they are star quality, they move into hetero movies. Many don't make the jump because the pay drops severely for men when they move from gay to hereto movies. The exceptions are very rare. For example, some lady wrote into her contract that she would only do anal sex with her husband. So, he got to be in her movies - but unpaid. Both documentaries also pointed out that the modern (post-VHS) pornography business is very different from the 50s through the 70s when the business was still run like a movie business. Now, it is a distribution business. The product is not important, just the quantity and availability. -- kainaw™ 03:34, 27 December 2009 (UTC)

Are you saying that all men who are in porn were in gay porn first? Dismas|^(talk) 06:12, 27 December 2009 (UTC)

yeah, that seems like an implausible reality. DRosenbach ^{(Talk | Contribs)} 13:57, 27 December 2009 (UTC)

I agree, very implausible. --Tango (talk) 14:49, 27 December 2009 (UTC)

Apparently some people need to read up on what "exceptions" means. I personally haven't tracked the filmography of every male porn actor. I am only relaying the content of two documentaries. -- kainaw™ 16:18, 27 December 2009 (UTC)

Nowadays, with internet distribution, naught but self-censorship prevents anybody from filming themselves doing whatever they want and attempting to sell it. The difference between art, blogging, and pornography is a very thinly legislated line that serves mostly for marketing purposes; there is no shortage of upscale user generated content/amateur pornography which is marketed as art of varying grades; etc. Probably the best answer to this question can be found in the humorous set of FAQs on Wikipedia's own Talk:Penis:

“ Q3: I would like to upload a picture of my penis.

A3: Unfortunately, the realities of supply and demand are not in your favor. There is a large supply of Wikipedia editors willing to photograph their penis in the name of science. However, the demand is much lower. If you feel that your penis is more deserving of placement on the article page, you are free to make your case below.

”

The same is probably true of male pornography - the reality of supply and demand does not favor males entering the industry. One way to change that equation is to act in alternative pornography, where there is (presumably) less supply. But nothing requires any member of the pornography community to ever act in anything they do not consent to (this is a well-defined legal distinction between a consented and non-consented act, e.g. exploitation or human trafficking). As such, the only barrier to males' porn success is marketability - the reality is, there is less demand for them. Nimur (talk) 17:24, 27 December 2009 (UTC)

I know what "exceptions" means - you said they were very rare. That may be true, but it sounds implausible to me. --Tango (talk) 17:46, 27 December 2009 (UTC)

The answer to both questions has changed slightly over the last few years as "home-based" porn has turned out to be rather profitable. Our articles on Heather Harmon and Wifey's World indicate that the answer to 1) is "with no trouble at all" and the answer to 2) is "have a hot wife". Your mileage may vary an enormous amount, of course. The old story about males having to go through gay porn first is probably not as entrenched as it used to be; the easiest way to become a male porno actor these days appears to be by simply buying a decent digital video camera, hiring the girl for POV work, and working out some kind of distribution deal either through an existing network or by starting up your own website/mail order. Matt Deres (talk) 19:37, 27 December 2009 (UTC)

LOL, By the way, if there's a science to pornography, I may have to go for my MSc! Do they still comp you for home study? Matt Deres (talk) 01:01, 28 December 2009 (UTC)

Yes Matt, with a big thesis you may matriculate. Cuddlyable3 (talk) 18:55, 30 December 2009 (UTC)

The association between gay (homosexual) pornographic performers and the aesthetic criteria for straight (heterosexual) male performers has a reason. The typical straight male viewer would like to identify himself with the male actor and what he is doing. This is easiest if the actor meets homoerotic desiderata such as being youthful, athletic, hairless and able to demonstrate genitalia that are physically dominating or even over-normal in erect size, activity and ejaculate volume. Preference for a particular straight male performer has nothing to do with how attractive he is to females, a lot to do with his availability, capacity for continual production and ability to act as ordered (read: not lose erection and ejaculate only when told to do so). There is no strong need to show a male's face in straight pornography but it is almost essential to show a female's face.Cuddlyable3 (talk) 01:35, 29 December 2009 (UTC)

Big bang?

Certainly there is substantial evidence of cosmic expansion, but what is the evidence restricting this expansion to only empty space? I mean, to say something is not expanding is like saying that it's not a part of the universe. The Earth is expanding underneath us while we all and everything around us expand as well. Considering its size though, the earth expands quickly in relation to us, so gravity, right? It seems they're trying to make this expansion be relative to some fixed point, but that leads back to a big bang which mathematically has been shown not to work. --Neptunerover (talk) 03:55, 27 December 2009 (UTC)

Um..what? Sorry, it's just not clear to me what you're saying. The Earth is not expanding appreciably, and any minute changes that occur in its volume are not related to the metric expansion of space. The expansion of space can truly be thought of simply as solid objects getting farther apart. And where has the big bang been shown mathematically not to work? I think that would be news to a lot of physics enthusiasts at this desk. Someguy1221 (talk) 04:07, 27 December 2009 (UTC)

Sorry, I think I mixed two questions there, really, I hadn't meant to bring gravity into it initially when I started the question. Isn't the big bang in conflict with quantum mechanics because of how it tries to jam a whole universe into a little plank space? I thought I read something about that anyway. I'm just wondering what the proof is that things are staying the same size relative to the space between them expanding. --Neptunerover (talk) 04:29, 27 December 2009 (UTC)

(EC) Gravity is NOT caused by earth's expansion. The earth is NOT expanding. Who is that 'they' you are talking about? The Big bang expansion is not relative to a fixed point. And the Big bang has NOT been shown not to work. Dauto (talk) 04:10, 27 December 2009 (UTC)

I guess I mean the scientists who study the expansion of the universe. And by the way, how could gravity from expansion be disproved? Constant acceleration. Its the same thing whether the earth is pushing us or pulling us.--Neptunerover (talk) 04:35, 27 December 2009 (UTC)

Disproved? Occam's razor isn't a proof, but there are lots of bizarre explanations that would account for ordinary phenomena in bizarre-seeming ways. I'm not sure we disprove them, so much as go with models that make more sense to us... -GTBacchus^(talk) 04:38, 27 December 2009 (UTC)

Exactly, make as few assumptions as possible. Constant size is an assumption, though a very understandable one to make. Einstein taught us though about relative perspectives being equal. Is the Earth pushing, or is it pulling. You say tomato...--Neptunerover (talk) 04:49, 27 December 2009 (UTC)

Except that the earth expanding model doesn't work. Try explaining how come the surface of the earth does not hit the moon within your expanding earth thingamagick model. Dauto (talk) 05:57, 27 December 2009 (UTC)

That's just a reverse of the same model, though instead of using size as a fixed reference point, it switches over to space.--Neptunerover (talk) 06:07, 27 December 2009 (UTC)

I understand what you are saying. But the problem is that this alternate model DOESN'T WORK. If the earth were expanding at such a rate it would hit the moon in short order. Dauto (talk) 06:13, 27 December 2009 (UTC)

I mean the Big Bang uses size as a fixed reference point while planets bulging into each other is just a switch of reference points. The goal should be to avoid those.--Neptunerover (talk) 06:14, 27 December 2009 (UTC)

Meaning please... Dauto (talk) 06:17, 27 December 2009 (UTC)

Okay, the big bang model keeps everything the same size, with only the distance between celestial objects changing. The opposite model would keep the spaces between everything constant while the objects increase in size, filling the space between them until there is no more empty space. Neither of those models works, so the space between objects expands while the objects expand as well. With everything expanding at the same time, it's not something that can be measured except against how it was in the past. It can only be indirectly verified, with redshift and I think, gravity. --Neptunerover (talk) 06:44, 27 December 2009 (UTC)

Why does space expanding not work? The space between gravitationally bound objects doesn't expand, is that where the confusion is coming from? --Tango (talk) 00:16, 28 December 2009 (UTC)

Space expanding works, but just not by itself. If that were the case, then the distance would increase between everything, causing there to be no local groups of anything. What we call gravity is just another way of looking at the reason there are local systems of planets, stars, etc., which is because space alone does not expand. With the space between the planets doubling in the same time that the planets double in size, there would be no noticeable change in the size of these things relative to each other, but we would get gravity. --Neptunerover (talk) 02:56, 29 December 2009 (UTC)

Neptunerover, if assuming that everything is expanding affords a better explanation of the phenomena than assuming that everything is staying the same size, then I'd say you've got something. Until then.... I don't see any gain in switching to that extremely counterintuitive model. Can you come up with some experiment that would distinguish everything-growing from not-everything-growing? If not, then it's not a testable hypothesis, and it's not in the realm of science at all. -GTBacchus^(talk) 06:58, 27 December 2009 (UTC)

See, that's why I asked the question. I noticed in a few articles where the assertion is made that the expansion is not in the size of things, but only in the space between them, but there's no citation for that, so I'm just a David Hume here saying, how do they know? If expansion is limited to only certain parts of the universe, then, why? I think it makes more sense the other way, and I think it sort of solves some things too. Like how can the universe be so young with all we know about the age progression of stars.--Neptunerover (talk) 07:29, 27 December 2009 (UTC)

Is there a constant for the gravitational force that could be compared to the rate of the accelerating universal expansion? That could be sort of like a test, I think.--Neptunerover (talk) 08:28, 27 December 2009 (UTC)

With that though, something may need to be accounted for with the Doppler effect, since with this idea of a uniform expansion, the distance between objects will not increase as much as it would if they were to stay small while just separating in space.--Neptunerover (talk) 08:54, 27 December 2009 (UTC)

With another way of looking at gravity (not a better way, but just another way(assuming it fits all the evidence)), maybe that could help people in figuring out a way of repelling it. Hey, and if nobody could copyright that, wouldn't it be great? --Neptunerover (talk) 10:06, 27 December 2009 (UTC)

Ok, wait a second. Neptune, just so I'm completely clear on what you're saying... Based on this section of your talk page, you are suggesting that the sensation of gravity may be interpreted not as us being pulled toward the Earth, but rather as the Earth pushing up against us as it expands? Is that right? Someguy1221 (talk) 10:20, 27 December 2009 (UTC)

I think so. When we consider we're dealing with spacetime, then maybe thinking of cosmic expansion as being an expansion through time as opposed to an expansion through space (which would be like an explosion) could help overcome this counterintuitive concept of an incessant bulging of everything. But what would expansion through time be? Another tricky hurdle of thought is required for that. --Neptunerover (talk) 11:24, 27 December 2009 (UTC)

Looking around us, even though everything is bulging, we don't see things bulging, because of what everything is bulging in relation to, which is nothing. Looking at it this way, the Earth stays the same size because there is nothing for it to be getting bigger than (Like the big bang has everything start from nothing, but if everything is getting bigger than nothing, does that require any actual change in size? With nothing to compare size to, I'm not sure there would be a noticeable size difference in things that are expanding in relation to nothing.) So the Earth gets bigger in relation to nothing, meaning its size stays the same. But if the earth is now staying the same size, what about gravity? It's the interchangeability of space and time that lets us keep the earth the same size in space while it remains expanding forward in time, and gravity is then the response to that expansion. That's what I'm thinking anyway.--Neptunerover (talk) 11:55, 27 December 2009 (UTC)

How does something "expand in time"? And why are space and time interchangeable? I'm no scientist, but I've hung around this refdesk for a while and I've never heard of either of these concepts. Vimescarrot (talk) 13:25, 27 December 2009 (UTC)

I just meant moving forward in time while considering what could possibly be a cause of that. --Neptunerover (talk) 20:06, 27 December 2009 (UTC)

I was thinking of spacetime as needing to remain steady, meaning if one thing occurs in space, then it needs to be accounted for in time as well, and vice versa. --Neptunerover (talk) 22:13, 27 December 2009 (UTC)

There is just one problem with this model: IT DOESN'T WORK! To create a sensation of gravity through expansion the earth's surface would have to be expanding at a rate of 9.8 m/s². Other planets with different surface gravity would have to be expanding at different rates to match their surface gravities. That does not fit your uniformly expanding universe. Your model is also unable to explain gravity's inverse square law. This model is no-good. Dauto (talk) 14:13, 27 December 2009 (UTC)

Okay. I thought it seemed too easy. --Neptunerover (talk) 14:55, 27 December 2009 (UTC)

I think you are confused about how the equivalence principle applies. It does not at all imply that the Earth is expanding—it implies that our sensation of gravity is completely physically equivalent to constant acceleration. Those are not the same thing, at all. --Mr.98 (talk) 15:36, 27 December 2009 (UTC)

So it doesn't imply the Earth is expanding, but rather accelerating in all directions at once. I get it. --Neptunerover (talk) 20:42, 27 December 2009 (UTC)

And that fits right along with the universe accelerating in all directions, so I think you're right. --Neptunerover (talk) 21:05, 27 December 2009 (UTC)

Maybe they should call it cosmic acceleration in all directions instead of expansion or inflation, which gives the impression of an explosion outward.--Neptunerover (talk) 22:19, 27 December 2009 (UTC)

OK, I'm now convinced that you are just playing around. --Mr.98 (talk) 00:07, 28 December 2009 (UTC)

I am sincerely not trying to play with or fool around with anyone. I'm just playing with an idea, and if it's right, then there is no proof for this non-uniform cosmic expansion model they're trying to push. I'm not saying it therefore must be wrong. How would I know? I certainly don't know all the details. It just seems to me they're assuming something without there being a valid basis for doing so, and so I came here wondering if there is any actual proof. I don't think they can prove that some things are expanding in relation to nothing while other things are staying the same size in relation to nothing. The word 'nothing' by itself does not indicate a size. You cannot say (the)nothing is small or that it is big, since these terms only apply to actual things that can be measured. (the)Nothing is absent of anything measurable, and so measuring anything in comparison to it is folly. Even trying to explain it could be folly because sentences don't only mean one thing. I just think for the big bang to suggest that universal expansion is an expansion in the size of the universe in comparison to nothing is absurd.--Neptunerover (talk) 04:12, 28 December 2009 (UTC)

The expansion of space is not "in comparison to nothing". The benchmark is the speed of light. See Metric expansion of space. Gandalf61 (talk) 07:21, 28 December 2009 (UTC)

Hey yeah, it mentions right there in [1.1] about expansion into time, which I was asked about before. So I thereby cannot be accused of making things up.--Neptunerover (talk) 07:53, 28 December 2009 (UTC)

Okay, let me look up this speed of light thing. --Neptunerover (talk) 07:53, 28 December 2009 (UTC)

Sorry, but I'm lost on what you mean by the benchmark of lightspeed. That sounds like another frame of reference, but doesn't the speed of light always recede as you approach it, like a rainbow? --Neptunerover (talk) 08:21, 28 December 2009 (UTC)

Not like a rainbow (which is a fixed angle, though perception of distance varies with terrain), but asymptotically (i.e. we can get as close as we like to it, but never reach it in finite time). Dbfirs 09:04, 28 December 2009 (UTC)

thanks for the term. --Neptunerover (talk) 11:03, 28 December 2009 (UTC)

Maybe the problem is that there are two ways of approaching the speed of light. One is through time, and the other is through space. Through space would be measured by size and mass, while through time would be what, energy? --Neptunerover (talk) 08:45, 28 December 2009 (UTC)

Don't you need both space and time to measure any speed?
Like you, I have never been happy with red-shift explained by receding galaxies or by expansion of inter-galaxial space. I have always felt (intuitively) that we are missing a wider viewpoint that would explain observations, but I don't think expansion (or contraction) of the local metric provides any alternative explanation. Meanwhile, metric expansion of 3-D space (excluding gravity-bound clusters such as galaxies) into the dimension of time seems to fit the observations, so it seems to be the best model at present. Dbfirs 09:13, 28 December 2009 (UTC)

I'm not sure time is well enough understood to say something like that. There's that problem with not being able to get a reading on both a particle's location in space and velocity. Maybe that is because the particle's velocity is through time, whatever that might mean...?Neptunerover (talk) 11:03, 28 December 2009 (UTC)

IT rather surprises me that anybody ready to embrace an expanding earth would be worried about an expanding universe being absurd. Rest assured though. There is no reason to worry. The universe expansion is a fairly simple thing. It's nothing more than the idea that the galaxies are moving away from each other. That movement has been clearly observed through the doppler effect. Most galaxies' light is observed to have a redshift which means they are moving away from us. Dauto (talk) 13:43, 28 December 2009 (UTC)

... or that the doppler effect is caused by some other aspect of space-time that we don't understand?
Does metric expansion of inter-galactic space imply that far-distant galaxies are actually travelling away in the sense of a real velocity? Dbfirs 14:48, 28 December 2009 (UTC)

Yes. By definition if their distance from us is increasing over time than they are travelling away. But extra care must be taken whenever talking about the speed of a distant object such as a distant galaxy. Unlike local movement It is NOT impossible for a distant galaxy to move away from us faster than the speed of light. Dauto (talk) 16:06, 28 December 2009 (UTC)

Point taken. I have this intuitive distinction between "relative velocity" meaning increasing distance with time, and "travelling" meaning "covering distance over time". I agree that, since there is no preferred inertial reference frame, the distinction is only in my imagination. Dbfirs 23:31, 28 December 2009 (UTC)

Small text is by Ref. Desk convention used for frivolous interjections. It should not be used for interpolative debating on the subject, neither by the OP, nor by someone who doesn't sign their post, and especially not by someone who lives in the error that IT'S is a posessive pronoun, as in the nonsensical construction "it's velocity is". Cuddlyable3 (talk) 00:52, 29 December 2009 (UTC)

I apologize, I've never experienced small text, and I was unsure how to respond to the small text that was in front of a paragraph of regular sized text, while making it clear the response was to the small text, so I thought responding with small text might work. I should've signed both sections I added with the one edit, and that was my mistake. (I'll copy the signature now to show when it was added.) --Neptunerover (talk) 01:21, 29 December 2009 (UTC)

... and I apologise for starting the small text with a comment that wasn't really frivolous. Dbfirs 07:38, 29 December 2009 (UTC)

Using successive indents (do by starting a post with colon(s) ) is the best way to show whether one is posting to an existing discussion thread like this one, or one may start a new thread without indent. Dbfirs in this manner I added to your indent and hope you don't mind. Cuddlyable3 (talk) 22:58, 29 December 2009 (UTC)

Not at all. (I hesitated on the indent because I was replying to both of the previous edits.) Dbfirs 12:31, 31 December 2009 (UTC)

diamond vs ceramics

Is diamond a ceramic? give reasons. —Preceding unsigned comment added by Kumar 3069 (talk • contribs) 07:06, 27 December 2009 (UTC)

That certainly sounds like a homework question, apologies if that assessment is wrong. There's plenty of information in both the ceramic and diamond articles that should allow you to reach a conclusion. If there's something you don't understand, then come back and ask a specific question. Mikenorton (talk) 12:12, 27 December 2009 (UTC)

Interesting question. Unfortunately, I don't know the answer. The Wikipedia page on ceramic has this description:

“ A ceramic is an inorganic, non-metallic solid prepared by the action of heat and subsequent cooling. Ceramic materials may have a crystalline or partly crystalline structure, or may be amorphous (e.g., a glass). Because most common ceramics are crystalline, the definition of ceramic is often restricted to inorganic crystalline materials, as opposed to the non-crystalline glasses. ”

It seems that the answer to the question hinges on the definition of ceramic. Diamond meets the criteria of being inorganic, non-metallic, solid, and crystalline. The part that's not so clear is whether it is "prepared by the action of heat and subsequent cooling." Heat is involved in at least some methods of synthesizing diamond, but whether that counts as "prepared by the action of heat and subsequent cooling" I don't know.

Can someone versed in material science provide a technical definition of what ceramic is? --71.185.178.230 (talk) 17:53, 27 December 2009 (UTC)

It may also depend on your definition of "organic". One sometimes sees chemists who will expand the title of "organic" to all carbon-based compounds even when they aren't associated with living things. Dragons flight (talk) 16:15, 28 December 2009 (UTC)

That was close to the generally accepted definition of 'Organic compound' when I studied chemistry decade or four back. Although the term 'organic' in this context originated in the belief that only life could create some compounds, which all happened to contain carbon, it was realised in the early 19th century that this was not so (see Organic chemistry) and the term was extended. Our article Organic compound currently says "There is no "official" definition of an organic compound. Some text books define an organic compound as one containing a C-H bond. Others state that if a molecule contains carbon it is organic."

With regard to the OP's question, does not the term 'ceramic' implicitly refer to manufactured materials? This would exclude natural diamond and similar substances; synthesized versions might be open to argument. 87.81.230.195 (talk) 02:15, 29 December 2009 (UTC)

Our article on solids says that ceramics are polycrystals (i.e. contain "grains"), which diamonds would not. Our articles seem not to concur as to whether this is part of the definition or just something that's typical. If someone does indeed know the answer to this question, the articles I've linked to (and ceramic) need to be harmonized. Matt Deres (talk) 04:47, 28 December 2009 (UTC)

It would seem that an agreed definition of ceramic does not exist [2][3][4][5][6]. Most authors, but by no means all, seem to be excluding diamond either explicitly or implicitly. SpinningSpark 03:12, 29 December 2009 (UTC)

Most diamonds aren't true perfect crystals (e.g. a lot of interstitial impurities) but AFAIK the amount of vacancy "holes" is very low relative to most metals and ceramic materials. Though I wonder about the interfacial impurities of diamond...I get the feeling that poorly connected "interfaces" simply fall apart (into separate diamonds). Compared to metal-metal bonds, C-C covalent bonds are very strong. Ceramic materials (homogeneous or heterogeneous) made of organic compounds, e.g. organic polymers are held together by hydrogen bonding, polar/ionic interactions and Van der Waals. Ionic bonds, while fairly strong, are fairly labile and easy to displace with other ionic bonds. This is prolly responsible for why diamond doesn't behave like many ceramic materials. AFAIK this makes diamond have very low molar entropy values -- because C-C bonds aren't very labile -- so there isn't a lot of room for "disorder" in diamond, (kinda why graphite is thermodynamically favoured over diamond at lower pressures).John Riemann Soong (talk) 08:36, 29 December 2009 (UTC)

nanocrystalline materials

What are the applications of nanocrystalline materials in automobiles? —Preceding unsigned comment added by 117.204.22.16 (talk) 07:12, 27 December 2009 (UTC)

Modern electronics rely heavily on semiconductors, which can be described as nano-crystalline materials. Nearly every modern automobile will contain at least a few semiconductor parts for control, power regulation, sensors, and any onboard computers. Nimur (talk) 17:39, 27 December 2009 (UTC)

Semiconductor devices usually are monocrystalline, not nanocrystalline. -Yyy (talk) 09:48, 28 December 2009 (UTC)

I don't think "nanocrystalline" is a well-defined term. Our article, nanocrystal, provides a definition, but I'm not certain it's in wide use. Nimur (talk) 00:53, 30 December 2009 (UTC)

Naked Singularities, Hawking Radiation, and Quantum Gravitation

Well, today I for no reason suddenly started to think about Black hole electrons. Well, but as the mass of a blackhole decreases, its Hawking Radiation should rise and electrons therefore are not stable. But then I knew if the electron was a blackhole, it would have to be a Naked Singularity. I then looked on the article for Hawking Radiation. Well, the sentence "Hawking radiation is required by the Unruh effect and the equivalence principle applied to black hole horizons" under "Emission Process" immediately caught my eye. So is it that Naked Singularities do not radiate Hawing radiation? Or (assuming electrons are black holes) they don't emit radiation just for some other reason like because the energy is more than the total energy of an electron(obviously including the mass energy from $E=mc^{2}$)?The Successor of Physics 14:31, 27 December 2009 (UTC)

That analysis relies on semiclassical theory, and only makes sense for black holes with masses much larger than the Planck mass. Otherwise the notion of Hawking radiation is not applicable - you need quantum gravity. 69.140.13.88 (talk) 16:33, 28 December 2009 (UTC)Nightvid

Tomato

Are tomatoes vegetables, or fruits? Or both? cheers--79.38.22.37 (talk) 15:37, 27 December 2009 (UTC)

See tomato and let us know if you have further questions. -- kainaw™ 16:20, 27 December 2009 (UTC)

Indeed. The article has an entire section that answers this. Ultimately, this is a question better suited for the language desk, because it deals with contextual word usage and the ambiguity of vernacular English. Both fruit and vegetable (...and tomato!) are terms that mean different things in different contexts. Typically, only "fruit" has a well-defined scientific meaning; in such a context, the tomato is clearly defined as a fruit. Nimur (talk) 17:33, 27 December 2009 (UTC)

According to Wiktionary, a Vegetable is:

1. Any plant.
2. A plant raised for some edible part of it, such as the leaves, roots, fruit or flowers, but excluding any plant considered to be a fruit, grain, or spice in the culinary sense.
3. The edible part of such a plant.

So a Tomato is a vegetable under (2) - but in a culinary sense, it's not considered to be a vegetable if it's also a fruit/grain/spice.

The Wiktionary definition of a fruit is:

1. (botany) The seed-bearing part of a plant, often edible, colourful/colorful and fragrant, produced from a floral ovary after fertilization.
2. Any sweet, edible part of a plant that resembles seed-bearing fruit, even if it does not develop from a floral ovary; also used in a technically imprecise sense for some sweet or sweetish vegetables, such as rhubarb, that resemble a true fruit or are used in cookery as if they were a fruit.

The Tomato is the seed-bearing part of the plant - it's edible, colorful and fragrant and it comes from the floral ovary - so there is utterly no doubt that it's a fruit under any sense of the term.

But under the definition (2) of "vegetable", it's ALSO a vegetable...unless you are talking in a culinary sense - in which case it's only a fruit.

However, people misuse the words "fruit" and "vegetable" all the time. Scientifically - they are definitely fruit AND also vegetables. In culinary usage - they are technically only fruit - but they are rarely called that because they aren't sweet like most other fruit. In common parlance they are almost always called vegetables. In government regulations, they are all over the map. It's a mess. But from a scientific perspective - they are most certainly fruit. SteveBaker (talk) 17:39, 27 December 2009 (UTC)

Actually, you have one bit backwards. A tomato is only a culinary vegetable, and not a culinary fruit, because it is used in savory applications. From a culinary (cooking) perspective, a fruit is something used in sweet applications, while a vegetable is used in savory applications. This is different from the botanical definition of fruits, a tomato is a botanical fruit because it is the seed bearing part of the plant. All culinary fruits are also botanical fruits, but there are MANY botanical fruits that are culinary vegetables. See also cucumber, squash, eggplant, chili pepper, etc. etc. which are, like tomatos, also botanical fruits, but not culinary fruits. In the botanical world, the word vegetable has no meaning, since vegetable is used only in the culinary world. A plant scientist would use words like "stem" or "leaves" or "fruit" to describe plant parts... --Jayron32 21:16, 27 December 2009 (UTC)

Not if you trust Wiktionary. It's saying that while scientifically, all fruits are also vegetables - in culinary terms, something is either a fruit or a vegetable...never both. But the dictionary definition of a fruit is unambiguous for things that are scientifically fruits - and only difficult in culinary terms when things like Rhubarb is considered to be a fruit. I don't see any way (with the Wiktionary definitions) for anyone to legitimately claim that a Tomato is NOT a fruit...although only non-culinary applications of the term 'vegetable' apply to the Tomato. I can't find another way to interpret that...unless of course Wiktionary is wrong. SteveBaker (talk) 03:11, 28 December 2009 (UTC)

What??? Steve, I can't really follow your logic here. Using the definitions you report (I won't check Wiktionary now because it might have changed in the mean time), a tomato is not a fruit under definition (2), because it's not sweet. So that means it does satisfy definition (2) of vegetable, because the exclusion "unless considered to be a fruit...in the culinary sense" does not apply (again, because it's not sweet).

Am I missing something in your argument? As far as I can see it's pretty simple: "Not sweet" implies "not a culinary fruit". (Except, I guess, for fruits that are so sour that it's difficult to taste their sweetness, but that are usually used with added sugar — I'm thinking of e.g. lemons here.) --Trovatore (talk) 07:36, 28 December 2009 (UTC)

"From a culinary perspective, a fruit is something used in sweet applications" ... "All culinary fruits are also botanical fruits" is arguable, I'd say. Rhubarb would likely be considered a fruit by most cooks (as "something used in sweet applications") but it's definitely not a botanical fruit. Carrots, however, quite firmly classed by cooks as a vegetable, are delicious in a "sweet application" such as carrot cake or Christmas pudding. The distinction isn't important (unless you're a government official trying to create red tape). Tonywalton ^Talk 01:36, 28 December 2009 (UTC)

Well, there aren't bright lines here; there are some foods that will stradle some of these distinctions; however those are very few. --Jayron32 01:52, 28 December 2009 (UTC)

Nonlinearity of the sRGB and Adobe RGB color spaces

The Wikipedia articles on sRGB and Adobe RGB articles state that both color spaces are nonlinear (with the latter having a gamma of 2.2 and the former approximately 2.2). So does it mean that if you use an image editor to create composite of a 50%-opaque image superimposed on another, 100%-opaque image, you are not getting the same resulting image as you would if you project the two source images onto the same reflective screen at half intensity? It seems to me that such non-linearity would create all sorts of unexpected weirdness when one is using an image editor, but I never noticed any. What gives? Do image editors internally use representations that are linear w.r.t. intensity when applying transformations and remap the pixels to the nonlinear color spaces on saving? Or is it true that the working representations are actually nonlinear, just that any "unexpected weirdness" is not noticed by most people? --71.185.178.230 (talk) 18:29, 27 December 2009 (UTC)

Bear in mind that the gamma in the image file is intended to counteract the 'typical' non-linearity present in the display device - such that when you double the brightness going into the image - you get twice the amount of light coming out again. Hence, you certainly wouldn't expect the results of adding two non-linear things together. Since gamma(a)+gamma(b) is not equal to gamma(a+b) - you would not expect your experiment to work unless the image editor is handling it right. In an ideal world, the loader for the sRGB image would convert it into a linear image for editing and convert back into non-linear as it displays it and when it writes it out to disk again...however, that's not always done properly - and a lot depends on which image editor you're using. But slightly more concerning is that you're talking about compositing by transparency...and that gets complicated since it depends on whether the alpha channel is also gamma-corrected. The whole thing is a bit of a mess...complicated by the fact that it's rare for any real-world display to have a gamma of 2.2 and not something wildly different. SteveBaker (talk) 02:59, 28 December 2009 (UTC)

Sound pressure, sound intensity, sound loudness, and decay with distance

This webpage http://www.sengpielaudio.com/calculator-ak-ohm.htm says that: "The sound pressure level (SPL) decreases with doubling of distance by (−)6 dB..... The sound pressure decreases with the ratio 1/r to the distance.

The sound intensity level decreases with doubling of distance also by (−)6 dB...... The sound intensity decreases with the ratio 1/(r^2) to the distance.

The loudness level decreases with doubling of distance also by (−)6 dB..... The loudness decreases with the ratio 1/(2^0.6)r = 1/1.516r to the distance."

My questions: a) how is the result "loudness decreases with the ratio 1/(2^0.6)r = 1/1.516r to the distance" obtained and is it correct? b) Is "loudness level" as described on that webpage the same as how subjectively loud a sound-noise is measured in db? c) What would sound intensity be in layperson's terms if it is not subjective loudness? d) Elsewhere on the page a "cylindrical wave" is mentioned. What would that be? Thanks. 92.24.73.139 (talk) 19:21, 27 December 2009 (UTC)

See Loudness and Stevens' power law for some of the ways in which people have tried to quantify psychological responses to stimuli. The equation you have a question about above is basically Stevens' power law for hearing. Stevens based his law by taking average results across a large number of people; basically its a law based on repeated experimental trials. It works a lot like the Scoville scale does for chili pepper hotness; its based on interviewing many many many people on their perception based on quantifiable initial conditions. For hearing, what you do is you place someone in an environment with a certain dB at a certain distance from the source, and then you ask them to rank their perception of the loudness of the sound. --Jayron32 21:10, 27 December 2009 (UTC)

The page means by "cylindrical wave" a wavefront that is spreading on a cylidrical surface. A wave emanating from a point in all directions will spread on a spherical wavefront. This is not usually particularly useful for sound systems as it wastes power sending some of up into the sky and into the ground. To generate a cylindrical wavefront the generator needs to be a line rather than a point. A column loudspeaker unit with drivers facing in all (horizontal) directions will approximate to this, see line array. A cylindrical wavefront spreads out in two dimensions only rather than three. SpinningSpark 22:16, 27 December 2009 (UTC)

Your power law for loudness doesn't look right. wouldn't it be 1/r^0.6 ? Dauto (talk) 01:30, 28 December 2009 (UTC)

I don't know, that's why I'm asking. 89.242.213.201 (talk) 10:41, 28 December 2009 (UTC)

The website's formula is wrong. Dauto (talk) 14:34, 28 December 2009 (UTC)

No it's not wrong, they are just not very clear in what they are saying. The basic relationship here is that subjective loudness is roughly reckoned (at most frequencies and levels) to double with an increase of 10dB sound level. This is an inexact relationship as it involves messy human beings. For a given decibel increase the loudness increases by x 2^dB/10. For a doubling of distance the sound level change is -6dB and consequently the loudness change is 2 ^{- 0.6}. SpinningSpark 22:56, 28 December 2009 (UTC)

And 2 ^{- 0.6} is not the same thing as 1/(2^0.6)r which shows that they are wrong. Dauto (talk) 06:21, 29 December 2009 (UTC)

Yeah, they're wrong. SpinningSpark 13:20, 29 December 2009 (UTC)

PTSD and hippocampus

In the page on PTSD, it says that Vietnam soldiers with PTSD were shown to have hippocampuses 20% smaller than avg. I had part of my hippocampus taken out and have been diagnosed with PTSD and mentioned that point to my neurologist and he said that such claims were purely anecdotal. Should that part be edited? —Preceding unsigned comment added by BroncoBuff (talk • contribs) 20:00, 27 December 2009 (UTC)

Discussion of a specific page should go on the respective Talk page, in this case Talk:Post-traumatic stress disorder. If the claim regarding the hippocampus is poorly-sourced, then editing may be necessary. If it has reliable sources, then one should support alternative viewpoints supported by similarly-reliable sources (conversation with a neurologist not being one of those). -- Scray (talk) 20:22, 27 December 2009 (UTC)

An interview with a neurologist would be a reliable source if it were published in a third-party, reputable journal or news outlet. If you conducted the interview yourself (presumably in the process of dealing with your own situation), then it constitutes original research and can't be cited in the article. There should be no shortage of research into physiological manifestations of PTSD - Hypotheses and controversies related to effects of stress on the hippocampus: An argument for stress-induced damage to the hippocampus in patients with posttraumatic stress disorder. (Journal of Hippocampus, 2001, vol. 11), seems to be a a good review of the different viewpoints about this particular physiological effect. Jeez, there's a journal for everything!Nimur (talk) 20:40, 27 December 2009 (UTC)

Let me note that our hippocampus article has some information on this. The basic story is that there is extensive evidence that many types of long-term stress, including PTSD, are associated with reduced hippocampal size -- we even have a pretty decent understanding of the biological mechanism by which stress damages the hippocampus. There is, however, no evidence that I am aware of that damage to the hippocampus can cause PTSD. Looie496 (talk) 15:47, 28 December 2009 (UTC)

Finite element method - solid or shell?

When using a linear FE code such as NASTRAN or a non-linear code such as LS-DYNA, when should you use solid elements instead of shells?

I.e. If the shells thickness is 5mm could a shell element of 1mm x 1mm be used? If not why not and what happens to any theoretical assumptions used? —Preceding unsigned comment added by Cjread58 (talk • contribs) 20:32, 27 December 2009 (UTC)

Solid element FEA is much more computationally intense than shell based methods. In return, it usually better matches the real-world physics. However, depending on your actual problem and parameters, this extra accuracy may be unneeded. It may also lead to instabilities. As far as element size, you might want to read the CFL condition for numerical stability. Also note that in addition to numerical stability, your element size also determines your smallest resolvable feature (or highest resolvable spatial frequency, if you prefer to think in that domain). See sampling or resolution (we appear to be lacking an article about the generic mathematical/sampling meaning for "resolution", but most other uses (e.g. optical resolution) follows the same conceptual rules as the generic-case numerical system. Nimur (talk) 21:06, 27 December 2009 (UTC)

Lost question

I wrote question a few days ago. it seems to have got lost or erased. Why is a gyroscope stable when spinning, but not when still? —Preceding unsigned comment added by 79.75.24.71 (talk) 23:32, 27 December 2009 (UTC)

I would tell you to look at the gyroscope page, except that the explanation there, while it might be technically correct, is pretty useless. If you understand the explanation - you don't need it. If you need an explanation, the one there will not help you. I would suggest using other resources besides wikipedia. Ariel. (talk) 00:59, 28 December 2009 (UTC)

Hey, Ariel — how about giving a try to improving that article? Comet Tuttle (talk) 01:08, 28 December 2009 (UTC)

angular momentum conservation. Dauto (talk) 01:21, 28 December 2009 (UTC)

Here's my attempt at a non-mathematical explanation. You can compare a fast-spinning gyroscope to a fast moving object, such as a bullet in space (no gravity). A small amount of momentum change in the bullet perpendicular to the bullet's direction of travel is not going to alter significantly the direction of travel. It is for a similar reason that a small amount of angular momentum change (proportional to torque × duration of torque application) is not going to change significantly the orientation of the gyroscope. It is important to know that this is true only when the angular momentum change is small relative to the angular momentum the spinning rotor has. The system of gimbals in a gyroscope allows the spinning rotor to be in any orientation relative to the enclosing environment to which the gyroscope may be mounted. In other words, the gimbals prevent transfer of torque to the spinning rotor. When the rotor is not spinning, even small angular momentum change can alter its orientation significantly. This is because, compared with zero (or something very close to it), even quantities otherwise considered quite small is quite large. --71.185.178.230 (talk) 17:24, 28 December 2009 (UTC)

An even simpler response would be to compare almost any object in motion, such as a spinning top or a running human, with that same object at rest. The chief concept is that, in motion, balance can be often be found even in a position that, if maintained during rest, would not exhibit balance. Thus, a top at rest cannot be balanced on its point and a human with many of the freeze-frame positions of running would not be balanced if the runner would be at rest. DRosenbach ^{(Talk | Contribs)} 19:22, 28 December 2009 (UTC)

While that appeals to a familiar observation, I don't think that's much of an explanation. --71.185.178.230 (talk) 20:27, 28 December 2009 (UTC)

71.185.178.230 - did you learn your explanation somewhere, or did you make it up? Because it doesn't sound right to me. And DRosenbach, 71.185.178.230 is right - that's not much of an explanation. A spinning top is stable because it is a gyroscope, not because it's moving. And human running is not stable at all, the human is constantly inputting energy to keep upright. Ariel. (talk) 21:39, 28 December 2009 (UTC)

I came up with the explanation myself. Which part of the explanation do you have a problem with? --71.185.178.230 (talk) 21:47, 28 December 2009 (UTC)

The whole thing. Force causes an affect relative to mass. It makes no difference how much momentum is already in the device. In your bullet explanation: The bullet is moving left, and you are pushing it down. The motion down will only care about how much force it was given in the down direction. It does not care at all about the motion to the left. If you measure how far down it travels after a certain time, that amount will be identical, no matter how fast it's going to the left. Ariel. (talk) 21:57, 28 December 2009 (UTC)

What you missed is that, in the bullet example, although the change in vertical motion (and velocity in particular) is not affected by the horizontal velocity, the amount of deflection (measured as an angle) is. The situation with a gyroscope is wholy analogous: the spinning rotor carries a certain amount of angular momentum, which determines its axis of rotation. If the angular momentum is large, small angular impulses (from sources such as air movement, friction at the gimbal joints etc) are not going to affect the angular momentum of the spinning rotor enough to affect the axis of rotation by much. Think of it this way: the angular momentum of the spinning rotor is a (long) vector in 3D space; the small external angular impulse is another (short) vector in 3D space. The vector sum of the two (and the direction it points at) is dominated by the long vector. --71.185.178.230 (talk) 22:21, 28 December 2009 (UTC)

I don't understand gyroscopes very well, but my best explanation of them is this: Imagine an upright gyroscope. (i.e. a wheel parallel to the ground, eg a sideways bicycle). Press down on one side of the gyroscope, and it will start to move down, causing the whole thing to tilt sideways. But one moment later, the part of the gyroscope that was moving down, is now on the other side of the gyroscope. It's still moving down. But now it's causing the whole thing to tilt in exactly the opposite direction. Ariel. (talk) 21:50, 28 December 2009 (UTC)

December 28

most appropriate article

I know the Wikipedia is not a "how-to" manual but many articles contain examples nonetheless to demonstrate or illustrate how something is done to help eliminate confusion in the article just as an image is added to an article to improve the article's clarity by incorporating the visual senses. In this regard I have a spreadsheet which uses an Excel add-in Solver function that incorporates linear programming to select the most cost effective combination of ingredients for production of several products to find the amounts of various foods to produce a completely balanced meal within the desired number of calories. The spreadsheet allows various foods to be added or subtracted (zeroed) from the spreadsheet in order to create a meal consisting of the specified amount of calories, fat, carbs, protein and fiber or any other constraint the user desires to use. There are several possible articles in which this example might fit best such as the article on Excel or its SOLVER add-in. It might also fit best in the simplex article or some dietary article. My question is what article readers will benefit from it the most?

(Note: There may be a better wiki converter routine than the one used to produce the wiki listing below so I have included a link to the .xls beneath it.)

Meal Planner	Source of nutrient	'	'	'	'	'	'	'	'	'	333.33	Objective calories	'	'
Variables	potatoes	milk	chicken	flax	c veg	egg w	soy	rice	raisins		RHS		LHS	Slack/Surplus
Objective Function	80	80	60	60	40	50	90	160	130	=	Target Calories		291.61
fats	0	0	9	45	0	0	36	13.5	0	=	66.67		66.67	0.00
carbs	0	48	4	16	32	0	20	140	124	=	200.00		200.00	0.00
protein	0	32	44	12	8	48	32	16	4	=>	50.00		50.00	0.00
Fiber	0	0	0	8	4	0	6	4	4	=>	16.67		16.67	0.00
	Results: Servings and grams
Servings	0	0	0	1.14379085	0.753449528	0.25493222	0	1.125635439	0
Grams	0	0	0	13.7254902	7.534495279	3.059186638	0	45.58823529	0
												L1 - To change the number of calories per day or the number of meals per day.
	grams											B26-B29:J26-J29 - To zero out conversion factor for grams to calories per nutrient type
	0	0	1	5	0	0	4	1.5	0			B20-B23:J20-J23 - to enter number of grams per nutrient for each food.
	20	12	1	4	8	0	5	35	31			N3 - Attained calories
	1	8	11	3	2	12	8	4	1			B10-11:J10-J11 - Results in number of package servings and grams
	1	0	0	4	2	0	3	2	2			Note: Spreadsheet utilizes the SOLVER add-in.
	calories per gram
	0	9	9	9	9	9	9	9	9
	0	4	4	4	4	4	4	4	4
	0	4	4	4	4	4	4	4	4
	0	2	2	2	2	2	2	2	2

The Excel worksheet may be downloaded from personal diet example. 71.100.6.153 (talk) 01:37, 28 December 2009 (UTC)

For what it's worth, and I have not the faintest idea what it's doing, what it's for, or whether the numbers it shows actually make sense, it loads and appears to produce some sort of results in my completely non-Microsoft environment (NeoOffice 3.0.1 on Mac OS X). So if it's meant to illustrate something specific to Excel or SOLVER these may not be appropriate articles to link to it. Maybe you could simplify it and generalise it to illustrate something about linear programming? Tonywalton ^Talk 02:00, 28 December 2009 (UTC)

Actually there are many good examples of this very process all over the net especially at many university sites that want to get students up and running quickly in the use of Excel and its Solver add-in. I had been using a computer program written in Visual Basic v6 to do the same thing but the Excel layout here is actually simpler and more adaptable to other uses. The idea here is the application of linear programming specifically to finding meals based on set number of calories and meals per day that produce a balanced diet according to any particular dietary regimen choice rather than intending to serve as a general application of linear programming. Some food or dietary article then me thinks best. 71.100.6.153 (talk) 02:30, 28 December 2009 (UTC)

IMHO, this is not the kind of thing Wikipedia needs - as you know - this is not a "HOW TO" guide. However, since you evidently don't agree with that assessment, I think you should go to one or more of those pages and start discussing it on the 'Talk:' page there. If there is widespread support for this amongst the authors of those articles - then you can go ahead and do it - if not, then it's better to quietly give it up because of the "not being a how-to guide" thing. You could (I suppose) "Be Bold" and just add it and see what happens - but since my personal inclination is contrary to that, I'd just go in there and revert your change - so you'd end up having to discuss it anyway. SteveBaker (talk) 02:46, 28 December 2009 (UTC)

A better converter would certainly help make it more presentable but what about just the link to the actual spreadsheet. In what article might that best find an acceptable place? 71.100.6.153 (talk) 02:52, 28 December 2009 (UTC)

Is this a project which would be better suited to the mandate of one of our sister projects — perhaps Wikiversity? TenOfAllTrades(talk) 03:23, 28 December 2009 (UTC)

Presenting the whole concept of linear programming is definitely worth the facility offered by the Wikiversity since for one thing the entire economy of the former Soviet Union used it to replace supply and demand but what I would hope to accomplish here is to provide individual readers interested in a mathematical means of creating a balanced diet that meets whatever calorie need they might choose both an example and a place to start, which might then lead them later to a full blown Wikiversity course. 71.100.6.153 (talk) 06:06, 28 December 2009 (UTC)

strange astronomical sight

Today at around 8:30 pm, while on a walk, I saw something pretty strange. The full moon was shining brightly through... a perfect circle of white clouds. The circle seemed so perfect that I think it needs a specific scientific explanation. I took two pictures with my cellphone. This happened in La Mesa, CA, USA. I'm really curious what could cause such a phenomenon. Supersonic jet, meteorite? Probably something more than just a trick of the wind. Thank you in advance. —Preceding unsigned comment added by 68.8.170.157 (talk) 05:04, 28 December 2009 (UTC)

I think semitransparent clouds covered whole sky more or less evenly, and the light from round moon highlighted a portion of these clouds. Hence the round cloud. (Igny (talk) 05:10, 28 December 2009(UTC))

Are you sure it was composed of clouds? Ice crystals in the upper atmosphere can produce such an effect, see 22° halo and Circumhorizontal arc 218.25.32.210 (talk) 05:21, 28 December 2009 (UTC)

The moon isn't going to be full for a couple of days, so your judgment of what makes for a "perfect circle" is a little suspect. Could you upload the pictures somewhere for us to check out? Without seeing the pictures, I'd tend to concur with my colleagues above - upper atmosphere droplets or crystals can be thin enough to be nearly invisible unless strongly lit from behind by the moon. Matt Deres (talk) 06:19, 28 December 2009 (UTC)

Here is the current moon in Maine, though perhaps it may be different in Caflifornia since you are farther west. :=) http://www.calculatorcat.com/moon_phases/phasenow.php?tcv=31 Gandydancer (talk) 07:15, 28 December 2009 (UTC)

I posted a picture of the moon with a 22^ohalo. did the phenomenon you saw look anything like that? Dauto (talk) 14:15, 28 December 2009 (UTC)

If someone wouldn't mind fixing the currently incomprehensible initial sentence in the 46° halo article -- I would do it myself, but I haven't a clue what it's trying to assert, and I left a message on the talk page which doesn't look like it's been visited about 60 times in the last year by no one who edited except for a page assessment. DRosenbach ^{(Talk | Contribs)}

I took a stab at cleaning up the language. It looked like some serious grammar issues, but I think I was able to make heads and tails of it. --Jayron32 20:58, 28 December 2009 (UTC)

I've tried for about an hour and a half to place the pictures online but had no success. Can someone walk me through the process? My cell is t-mobile. —Preceding unsigned comment added by 68.8.175.233 (talk) 22:10, 28 December 2009 (UTC)

IPs are not permitted to upload images directly to Wikipedia. You will have to upload it to Commons, or else to some other site like Flickr and then link it. SpinningSpark 23:17, 28 December 2009 (UTC)

Hmmm, well it seems nothing special about the moon xxx saw. But watch closely folks, we're going to have a BLUE MOON on New Years Eve! Gandydancer (talk) 21:15, 29 December 2009 (UTC)

Fischer esterification with amino acids -- worried about the protonated amino group

Is there anything particularly tricky about esterifying an amino acid with an alcohol with acid? The amino group is protonated and I'm worried that'll discourage protonation of the carboxyl group. But .... is the protonated amino group such a big problem? I know the alpha-COO- group is particularly acidic and would definitely not like a second proton, but since the amino group is electron-withdrawing right -- that should encourage esterification even if the carboxyl group is particularly hard to protonate? John Riemann Soong (talk) 05:31, 28 December 2009 (UTC)

Extraterrestrial intelligence

The universe is so large and there may be many undiscovered galaxies, which means possible undiscovered stars and planets. There may be undiscovered planets in habitable zone. Then why scientists deny the possibility of existence of extraterrestrial intelligent life forms? --Qoklp (talk) 10:50, 28 December 2009 (UTC)

Do they? Vimescarrot (talk) 11:48, 28 December 2009 (UTC)

Take a look at the SETI article, there are an awful lot of scientists involved in actively looking for extraterrestial intelligence. SpinningSpark 11:54, 28 December 2009 (UTC)

I was going to say something along the same lines. A good scientist probably would not "deny the possibility of existence of extraterrestrial intelligent life forms?". There may be a lack of verifiable evidence from reliable sources. People claim to have been taken on board 'spaceships' by 'aliens' but not too many of these people are 'rocket scientist' types (I may be being a bit uncharitable here). Space is certainly very big, lots of galaxies, star systems, planets etc. It would be a "waste of space" wouldn't it? I recall that Carl Sagan believed that it was very possible. --220.101.28.25 (talk) 12:03, 28 December 2009 (UTC)

See also Rare Earth hypothesis and Drake Equation --220.101.28.25 (talk) 12:14, 28 December 2009 (UTC)

No scientists really think that there wouldn't be extraterrestrial intelligent life forms, somewhere, at some time. They just deny that there is any evidence that humans have yet been in contact with any E.T.s., or have differing opinions on the odds of humans ever having contact with said E.T.s. (See the Drake Equation for one attempt to narrow down the parameters of what it would require to be able to communicate with an E.T. civilization.) --Mr.98 (talk) 16:49, 28 December 2009 (UTC)

It is a mystery how the OP can link to the article habitable zone that speaks about "the likeliest candidates to be habitable and thus capable of bearing extraterrestrial life similar to our own" but allege that scientists deny this possibility. Actually reading the article would be a good move. Cuddlyable3 (talk) 00:03, 29 December 2009 (UTC)

Anatomy classes - Truth or myth?

Anatomy class: The Professor sticks his finger right up the guts of a dead man, pulls out his finger and sticks it in his mouth. The students just stand there, paralyzed at what they see. He says: Now, go ahead and do the same thing, each of you. Freaked out, the students take several minutes but eventually take turns sticking their fingers up into the guts, and then sucking on them. Once everyone is finished, the Professor continues on with his lesson. He: now, the most important quality you must possess is a keen observation. You see, I stuck in my middle finger up the butt, and I sucked on my index finger. Now, learn to pay attention.--Quest09 (talk) 19:55, 28 December 2009 (UTC)

Neither - it's a joke. --Tango (talk) 19:58, 28 December 2009 (UTC)

OK, it sounds as a joke and it´s told as a joke. But how can you know that it didn´t happen at least once?--Quest09 (talk) 20:05, 28 December 2009 (UTC)

You could ask that about any joke told in the form of a story, couldn't you? Vimescarrot (talk) 20:09, 28 December 2009 (UTC)

There's a variation of this regarding testing urine for the sugary indication of diabetes, as well. (Which snopes has a page on, incidentally.) It's the kind of joke that professors like to tell. Har har. --Mr.98 (talk) 20:18, 28 December 2009 (UTC)

Well, diagnosing diabetes by tasting the urine (if it's sweet there is glucose in it and the patient is probably diabetic) is a genuine diagnostic technique. It isn't used these days since we have little sticks that change colour when exposed to glucose, so doctors prefer those. Urine is perfectly sterile and safe to drink, there is really no downside to the technique. --Tango (talk) 20:47, 28 December 2009 (UTC)

I myself have seen it with my own eyes. Intended as a joke, of course, and with urine (well, yellow liquid) rather than a corpse. Tevildo (talk) 20:25, 28 December 2009 (UTC)

An apocryphal story also told about a chemistry professor who "tastes" a beaker of urine by dipping one finger in it and sucking another finger. Professors like their jobs, which is why you can be pretty sure this never happened. - Nunh-huh 20:24, 28 December 2009 (UTC)

Yeah, my 9th grade bio teacher did this with urine, too. DRosenbach ^{(Talk | Contribs)} 20:33, 28 December 2009 (UTC)

This is an easy one. Assume it is true. A professor purposely tricks students into potential viral and/or bacterial infections. If not treated properly, they could be life threatening. The only result of this insanely stupid act is that it becomes a common joke. In what version of reality is such an event possible? Perhaps on the show House (which is a very strange version of reality where doctors only see one or two patients a week). -- kainaw™ 21:49, 28 December 2009 (UTC)

Since the term "guts" may refer to any part of the Human gastrointestinal tract it is not obvious that the OP means the cadaver's anus, nor how gustation of rectal debris might advance one's education in anatomy. To research further on the subject that interests the OP, see this article and the acronym ATM; tutorial videos produced by dedicated professionals are available but deprecated since they do not provide health warnings, and there are probably somebody's mothers and sisters there. Cuddlyable3 (talk) 22:58, 28 December 2009 (UTC)

This joke is also in Mark Perakh's collection of Russian jokes. [7] bibliomaniac15 23:05, 28 December 2009 (UTC)

Drifting gently away from the strict topic, but my father recounts having seen a more elaborate version of this prank while in a military hospital ward, which involved a spurious request to the duty nurse for a bedpan, the surruptitious insertion therein of limeade and a large cooked sausage, and a 'helpful' ambulatory inmate who, while returning the bedpan to the nurse paused, picked up the dripping sausage and bit off a chunk remarking "There's not much wrong with him." 87.81.230.195 (talk) 01:49, 29 December 2009 (UTC)

Yes, all very funny in an ewww kind of way, but seriously? One of the biggest problems facing anatomy departments is cadaver supply, and some of that has to do with perceptions of disrespectful behaviour toward the cadavers. A very big deal is made about respecting the hugely generous donation a person and their family has made before you get to go anywhere near one for dissection purposes for that very reason. Unfortunately, there have been instances of people behaving disrespectfully toward cadavers, and they're ususally promptly ejected from the faculty under a zero tolerance rule. There's no way any self-respecting anatomist would do that, these days at least. Mattopaedia ^{Have a yarn} 14:47, 29 December 2009 (UTC)

If we inject oxytocin into a female

Human female or any cow - whatever is at hand- would she start producing milk? --Quest09 (talk) 20:03, 28 December 2009 (UTC)

As our lactation article explains, there is a lot more needed than oxytocin. Looie496 (talk) 23:16, 28 December 2009 (UTC)

Oxytocin is used on many dairy farms to get certain cows to let down when they're being milked. It doesn't make the cow produce any (more) milk to begin with though. If it's used on a consistent basis, the cow will eventually need it in order to let down at all. Dismas|^(talk) 03:40, 29 December 2009 (UTC)

New way to generate electricity - has this been proposed before?

I would like to know if this idea has been proposed an if there is a name for it. Otherwise, will this work? The idea is to use buoyancy of a large ammonia filled balloon to generate power, where the power ultimately is obtained from the vertical temperature gradient in earth's atmosphere:

Have a large ammonia (gas) filled balloon tethered to a reel that's connected to an electrical generator with a clutch. Right below the balloon is a small thermally insulated tank. To achieve the desired altitude of 10-20km it might be necessary to add an additional hydrogen filled balloon of adequate volume to the top. The clutch is only engaged when the balloon is rising. A small engine can reel the tether in when the clutch to the generator is disengaged.

When the balloon is released at ground level it will rise up and generate electricity. It will rise to an altitude of 10km or more where ambient temperature will cool the ammonia down to below its boiling point of about -33 degrees Celsius with some thermal delay. All liquid ammonia that forms runs into the insulated tank at the bottom. Once enough liquid has run into the tank the balloon will begin to descent while the tether is reeled in with little resistance. More ammonia will condensate until the balloon has dropped to an atmospheric level almost equal in temperature to the boiling point of ammonia, at which point the insulated tank is closed at the top. The balloon will continue to descent, but start to slow down again as the weight of the hanging tether is reduced.

When the balloon stops descending the clutch is engaged again and the insulated tank is opened again for the ammonia to evaporate, which will happen at the relatively warm ambient temperature at the low altitude. The process repeats. During design the size of the balloon(s) and the tank need to be balanced with the weight of the tether to ensure that the system rises very high and descends quite low, but not so low as to risk hitting the ground.

As a bonus, if the balloon is reeled in all the way, the liquid ammonia could be used to drive a heat engine like an ammonia "steam" engine to have the liquid replaced by warmer gaseous ammonia of equal mass for the next round. Multiple systems like this can work in parallel at different stages simultaneously.

The ammonia and possible hydrogen balloons need to be semi collapsible and can be constructed using technology such as a Hoberman Sphere covered in a stretchable membrane. I did the math and if this is possible then the cube-square law makes this method of electricity generation very effective and scalable.

196.210.200.164 (talk) 20:59, 28 December 2009 (UTC) EonZ

The two big challenges I see are that it requires a lot of moving parts to move very large volumes of gas, and also that the heat capacity of air (particularly stratospheric air, at rather low pressure) is quite limited; that means that we need to move large volumes of air into contact with our system, and that the chilling/warming cycles may take a long period of time. Both of those factors mean a lot of balloons and some costly equipment.

While I'm not familiar with such a generator operating in the manner you describe, there are a number of pilot projects which exploit temperature differences between surface and deep-ocean water. Our article on ocean thermal energy conversion gives the details. In those systems, they avoid the problem of collapsing and inflating balloons and reeling cables in and out by moving the ammonia working fluid up and down through fixed pipes. TenOfAllTrades(talk) 21:26, 28 December 2009 (UTC)

Yes, it would work. It's basically a Stirling engine with the hot and cold side separated by a great distance. Ariel. (talk) 21:30, 28 December 2009 (UTC)

Note that "it would work" is not the same as "would be a feasible way to generate electricity". There's lots of ways to technically generate electricity which, like this method, are not viable for commercial power generation. You can generate electricity by paying people to run on treadmills, or by capturing cow flatulence in large balloons and burning it, or by any number of wildass methods, the question becomes if these methods produce enough electricity at a low enough cost to be viable. I can't see where your method would... --Jayron32 21:42, 28 December 2009 (UTC)

Since cows are domesticated, wouldn't that example be a tameass method? 87.81.230.195 (talk) 01:37, 29 December 2009 (UTC)

At 10-20km the ammonia will be at reduced pressure so it needs a lower temperature to cause condensation than the boiling temperature at atmospheric pressure. Keeping the condensed ammonia liquid during the descent to warmer temperature could be done more reliably by locking it into a pressure vessel than in an unpressurized insulated tank. I am not sure how you prevent the balloon stabilising at an intermediate height. The weight of 10-20km tether is significant. Unless your "small engine" can pull in the tether faster than the balloon sinks, the tether and possibly the balloon will hit the ground.

The balloon is at the mercy of any wind. Both the tether and the "small engine" must be strong enough to overcome all wind forces.

The balloon and its tether are hazards to aircraft. Legalisation of a no-flight volume will be needed, in principle a 20km radius hemisphere centred on the tether reel.

Pure ammonia is corrosive. The implications of a balloon full of ammonia hitting the ground anywhere in a populated area, and at an unpredictable distance if the tether breaks in a storm, are disturbing.

The Hoberman sphere is a complex multi-jointed construction that seems to give a lot of failure points and no advantage except increased weight relative to a simple flexible gas bag. Cuddlyable3 (talk) 22:19, 28 December 2009 (UTC)

There are any number of ways of exploiting a temperature gradient to extract energy - so the only real questions here are whether this is the most efficient temperature gradient to exploit - and if so, whether this is the best way to exploit it. My feeling on the first question is "No" - because geothermal approaches and (as TenOfAllTrades says) deep ocean temperature gradients are much more accessible and stable. If you absolutely had to exploit an air temperature gradient - then I suppose this might work - but the practical problems are pretty severe. Remember - you can extract energy from pretty subtle temperature gradients with things like the Drinking bird toy - or, more practically, with a stirling engine. SteveBaker (talk) 00:31, 29 December 2009 (UTC)

Thanks for the educated comments. Wind and stormy weather was also my biggest concern, especially when reeling in. I thought about it and only the ammonia balloon would need to be collapsible (because some gas is removed to the tank). A hydrogen one can be just a stretchable sphere. The ammonia balloon can also be a long cylindrical one along the tether for greater surface area. But I think I found the flaw in my idea from TenOfAllTrades's comments: because this system relies on transfer of heat, the average power generated by the duty cycle depends on surface area of the balloon and not volume. The surface material is heavier than air so the system is not so scalable as I'd hoped (I was thinking balloons with like 100m diameter). 196.210.200.164 (talk) 07:08, 29 December 2009 (UTC) EonZ

Interesting idea.Supposing the balloon had a fractal shape to vastly increase its surface area to improve heat exchange? Would this make the process viable?[Trevor Loughlin] —Preceding unsigned comment added by 80.0.111.234 (talk) 08:46, 29 December 2009 (UTC)

The problem is that a fractal shape would (in the limit) be likely to have an infinite area and zero volume - which means it won't fly. More particularly - the mass of the (empty) balloon is likely to be approximately proportional to it's surface area - so when you increase the area - you have to increase the volume at least proportionately in order to keep it able to fly. This would allow you to have (in principle) a surface area that's proportional to the volume. You don't need a fractal to do that. Take a long, thin cylindrical balloon. If you doubled the length and kept the diameter the same - then you doubled the volume and doubled the surface area...so it should still fly. So you don't need fractals to get the optimum surface-area-to-volume ratio - you're always limited by the lifting power of your gas. SteveBaker (talk) 19:55, 29 December 2009 (UTC)

We have tried to talk to SteveBaker about his regrettably deviant proclivity for dysfunctional English prose constructions like "proportional to it is surface area" and what has been learned? Cuddlyable3 (talk) 22:42, 29 December 2009 (UTC)

The use of wind generators attached to a dirigible was discussed for Venus landers. At [8] see comments by Guest_DonPMitchell_ at his post May 17 2006, 06:05 PM. In the dense atmosphere of Venus, the unmanned airship would be made to rise and fall by expanding a steel bellows to make it lighter than air. Wind powered generators would generate power during the resulting vertical motion. I would like some reassurance that there is no violation of conservation of energy in such a scheme as that, or the one the OP proposed. Is the drawback just the small amount of energy that could be generated? The Minto wheel was a 1970's device which was essentially 2 or more Drinking bird toys made into a continuously rotating wheel. When one was built, 10 feet across or more, it turned very slowly but with considerable power, with a phase changing gas/liquid system something as described for the balloon by the OP. It did work, contrary to what the article says, but was disappointingly slow. A pair of the OP's balloons could operated in tandem, one rising at a time to provide continuous power, with a clutch connecting them alternately to the generator or a winch to withdraw the line as they fall. How much lift would come from how big a balloon? That and the speed of rise determine the power input to the generator.The time required for the working fluid to condense and let the balloon back down would determine the power output per day. Edison (talk) 22:08, 29 December 2009 (UTC)

December 29

Electronic locator

Hello. I'm thinking of taking my little nephew out to play in a small wood (without any streams or water) and it seems likely that he'd want to run off and play hiding games. Perfectly natural, and good fun, but I'd feel more comfortable if I could 'tag' him in some way to make him easy to find quickly if need be. I'm imagining something small that straps to the wrist, that would feedback to something small I kept. Perhaps like 'homing beacons' in old spy dramas, with a little screen that shows roughly where he is and how far away. Or maybe audio feedback like a metal detector. I'm sure such things must exist. Any suggestions?

I'd even welcome suggestions on how to make my own, although I'd need a link to a good walkthough if it involves circuitboards. 86.176.48.114 (talk) 01:11, 29 December 2009 (UTC)

Here is an external commercial link you might try. 71.100.6.153 (talk) 01:29, 29 December 2009 (UTC)

Thanks. In forming my question (and thinking of an appropriate title) I actually gave myself some good search terms to find a few in the UK. I've got one that looks likely, although it is very expensive considering I'm not sure how often I'd use it. It's similar to the ones you've linked to, but a bit more multipurpose. I'm still open to suggestions for something simpler (cheaper), although I'm slightly tempted to buy the one I've found just for the "we're living in the future" feel of it. 86.176.48.114 (talk) 01:36, 29 December 2009 (UTC)

A key chain whistle might be a decent low tech solution provided the nephew is within a certain minimum radius. Noodle snacks (talk) 05:40, 29 December 2009 (UTC)

That's true, assuming he hasn't knocked himself out with a rock :) It's one of those silly things where if he were my child I'd be willing to take the risk, but since he's my brother's I feel like I have to be more sure. Thanks: maybe I'll get him blowing the whistle for fun before releasing him, and hopefully he'll enjoy the loud noise enough to keep doing it from time to time, even if he doesn't think he's lost. Makes for a good game of fox and hounds. 86.176.48.114 (talk) 14:31, 29 December 2009 (UTC)

wierd phenomonon

There are cirus clouds in my area (clayton,nm,USA) and right by the moon there is this gaping hole in the clouds. What is this?Accdude92 (talk to me!) (sign) 03:25, 29 December 2009 (UTC)

It's not a hole. It's an illusion. You see the clouds only because of the light from the ground. The moon is so bright, that all you see is the moon, and not the light from the ground reflecting on the clouds. If you watch for a while, you might be able to see a slight fuzziness over the moon from the clouds. It's much easier to see if the moon is not full. Ariel. (talk) 04:48, 29 December 2009 (UTC)

but its a huge hole!Accdude92 (talk to me!) (sign) 04:57, 29 December 2009 (UTC)

Does it look like this? HERE --220.101.28.25 (talk) 07:38, 29 December 2009 (UTC)

Yep!Accdude92 (talk to me!) (sign) 15:30, 29 December 2009 (UTC)

It's not a hole. it's a halo. Dauto (talk) 17:20, 29 December 2009 (UTC)

There is one that can be seen around the Sun too, but it's really bright looking in that direction, so that is not recommended. I think it is some prismatic effect that comes from any light source. Look at a candle flame; it has a halo, and I think that's the same principle.--Neptunerover (talk) 02:41, 30 December 2009 (UTC)

I don't think so. I don't know what you are talking about but halos are caused by ice crystals floating in the atmosphere. Not something one would expect to happen around a candle flame inside a home where it is nice and warm. Dauto (talk) 14:03, 30 December 2009 (UTC)

As others have suggested, this 'hole' is part of an atmospheric halo phemomenon, caused by ice crystals floating in the apparently clear or near-clear sky. As in this [9] diagram (on a generally relevant site), when a bright halo is formed in a circle around the Sun or Moon it is composed of light from within the circle that has been refracted, resulting in the circle's inner area being a littler darker than the sky overall. This is very hard to see around the very bright Sun (though a similar effect called Alexander's band is more observable outside an ordinary rainbow opposite the Sun). When the dimmer Moon is in the night sky, the effect is more obvious. 87.81.230.195 (talk) 15:52, 30 December 2009 (UTC)

Sulfuric acid and wax

Will sulfuric acid dissolve any kind of wax? If so, which kinds does it dissolve most efficiently? 69.111.79.27 (talk) 04:47, 29 December 2009 (UTC)

Sulfuric acid will not, but Magic acid and Superacid will. Ariel. (talk) 04:50, 29 December 2009 (UTC)

Depends on what you mean on "wax" I guess. Waxy substances with double bonds in them (ester/amide type groups, alkenes) or aromatic groups may react and "dissolve". John Riemann Soong (talk) 06:02, 29 December 2009 (UTC)

Also depends on what you mean by "dissolve". Magic acids will outright protonate saturated compounds and that proton will stay on, helping remain the compound remain "dissolved". With sulfuric acid, it might catalytically put a proton on an unsaturated molecule, ripping it away from a hydrophobic crystal lattice into solution, and may or may not catalyse some sort of reaction (e.g. hydrolysis, sulfonation). But then the proton comes off and the product is insoluble, giving you a sort of colloid rather than a real solution. (After neutralising the acid, you can collect the precipitate by letting it sit and/or centrifuging it). John Riemann Soong (talk) 07:01, 29 December 2009 (UTC)

are hydride donors compatible with thionyl chloride?

Just checking ... replacing -OH (or -COOH) with -H isn't really a possible as a one pot synthesis with these reagents right? If it is possible, is using Tris(pentafluorophenyl)boron (+ n-butyl silane), are there any additional advantages besides convenience? (Wondering about cost, yield/efficiency, messiness, industrial production, all that jazz, etc.) John Riemann Soong (talk) 05:03, 29 December 2009 (UTC)

Reason for the variable names in the Lagrangian

The formula is L = T - V where T is kinetic energy and V is the potential energy. What do these symbols stand for? Why these instead of $E_{K}$ and $E_{U}$ or K and U like normal? (And why U?)-Craig Pemberton 06:30, 29 December 2009 (UTC)

T and V are normal. Dauto (talk) 06:38, 29 December 2009 (UTC)

They also show up in Hamiltonian mechanics as well. However, the OP is not the only one to note the difference in usage. The article Lagrangian mechanics notes that Lagrangian uses T & V where other contexts use K and U. Not sure why two contexts are using 2 different sets of variables for the same thing, except to note that K and U are just as arbitrary as T and V, so I don't really see why either makes much of a difference. --Jayron32 06:42, 29 December 2009 (UTC)

I'm not saying that one is better than the other, just wonder what the etymologies and historical differences might be.-Craig Pemberton 06:44, 29 December 2009 (UTC)

What is Quantum Action?

I'm trying to understand Feynman's Path Integral Formulation, but I don't seem to get what is quantum action. Can anyone please kindly explain it to me?The Successor of Physics 07:11, 29 December 2009 (UTC)

See Action (physics). Quantum action just means that the correct value is obtained by integrating energy of the Lagrangian with respect to time (as in classical action), but where the Lagrangian is quantized and calculated according to the rules of a particular quantum mechanical system. As far as what action is, it is simply a physical parameter of the system. Action represents the difference between kinetic and potential energies. According to the Principle of least action (which is essentially just an empirical observation that is mathematically consistent as a generalization of classical mechanics), a system prefers to obey motions such that action is minimized; Feynman's approach solves the system according to a path integral representation of this principle. Nimur (talk) 08:14, 29 December 2009 (UTC)

I still don't get the idea of the physical interpretation of quantum action, and how do you calculate it?The Successor of Physics 12:16, 29 December 2009 (UTC)

How familiar are you with canonical quantization and classical classical action? Dauto (talk) 14:31, 29 December 2009 (UTC)

You calculate quantum action by integrating the Lagrangian with respect to time. If you don't know how to construct a quantum mechanical system's Lagrangian, then Lagrangian mechanics is the first place to start. Do you have a specific example? Often, the quantum harmonic oscillator is the example problem for such derivations. You can construct a quantized lagrangian for that system, and then integrate it. As I alluded to above, "intuition" is not necessarily going to take you far here - first, the classical formulation of action is fairly abstract. You have to gear your mind to think in terms of energy - I imagine little "gas tanks" full of Kinetic and Potential energy, and as the system changes state in state space, gas pours from one tank to the other... and then you want to minimize the Lagrangian as you integrate with respect to time. (See, the intuition is a little weird in even the classical case). Then you quantize the gas tanks... (energy levels) - so you can't pour energy between the two tanks continuously - but must transfer energy in discrete amounts, with quantities determined by the present quantum state space representation of the system. Nimur (talk) 01:00, 30 December 2009 (UTC)

Is this plausible?

http://www.snopes.com/college/risque/telltale.asp

Can sperm really last that long in the mouth? Are they easily visible in high school microscopes? Are they easily identifiable as sperm cells (easy enough for high school students to recognize them without the lab assistant's help)? --99.237.234.104 (talk) 09:36, 29 December 2009 (UTC)

How long are you talking about? You don't know what she was doing right before class, do you? Spermatozoa would be visible in high school micropscopes but may not be readily identifiable by the inexperienced observer because they're quite small, the head being about 1/3 the diameter of your average red blood cell, and quite considerably smaller then squamous cells, which you see most of in a buccal smear. Depending on how long they were there for, there'd be a variable degree of degradation, and the background may also include food residues, yeasts, bacteria, degenerate squames and other debris that would also make spermatozoa hard to identify, unless there was a huge number of them. Let your imagine take that where it will... Cheers! Mattopaedia ^{Have a yarn} 15:01, 29 December 2009 (UTC)

If not too much time had passed, the wiggling motion would be distinctive and highly noticeable, compared to the other things usually found in buccal swabs. Edison (talk) 21:49, 29 December 2009 (UTC)

Autonomous Intelligence

What would happen if the mighty WikipediAI (meaning a Giant Knowledge Computer able to think Autonomously -- the GWACK or WikiGACK, or..) that we are all creating here were to gather all this physical sciences information together and from that figure out a solution to 'quantum gravity' and maybe some other things. Could WikipediAI win the Nobel Prize? --Neptunerover (talk) 09:43, 29 December 2009 (UTC)

Uh..., I think you should put this question on another reference desk like the computing one.The Successor of Physics 12:11, 29 December 2009 (UTC)

Nobel Prizes are awarded to persons who have "bestowed the greatest benefit on mankind". Nominated persons must be alive. This would seem to rule out any kind of machine. SpinningSpark 12:41, 29 December 2009 (UTC)

So I guess then it would need to be awarded to all the persons who contributed to the Wikipedia knowledge space. Even better. --Neptunerover (talk) 12:57, 29 December 2009 (UTC)

There is a big difference between intelligence and knowledge. Wikipedia has great knowledge, but no intelligence. --Tango (talk) 13:46, 29 December 2009 (UTC)

I was wondering about that very paradox earlier: How much knowledge does it take to be wise? --Neptunerover (talk) 00:56, 30 December 2009 (UTC)

What paradox? Intelligence and knowledge are just different things. Wisdom is, again, a different thing. They are related, certainly, but they are different. --Tango (talk) 02:15, 30 December 2009 (UTC)

I guess the paradox is for people who confuse them, since neither leads to the other, although when used together, they work very well. --Neptunerover (talk) 02:29, 30 December 2009 (UTC)

I've been sitting outside the university's library for years, and I still haven't seen it come up with the solutions to any problems. Why should we expect an electronic medium for storing bits to suddenly be more inspired than a paper medium? In any event, Wikipedia expressly not a venue for original research. TenOfAllTrades(talk) 14:33, 29 December 2009 (UTC)

But if Wikipedia could be proved as the epicenter of a vast paradigm shift, then nobody would ever be able to claim the idea was originally theirs. I mean not a one here among us does not stand on the shoulders of giants. Without those who amassed all this knowledge, we would not be able to put it all together here. What if by putting it all together in this form (the transfer of the printed books to this medium), it just comes together all by itself, and tah dah! --Neptunerover (talk) 00:56, 30 December 2009 (UTC)

On my user page, some time ago, I put a little quip about Wikipedia being an inevitable part of technical and social progress. This free internet-based encyclopedia is simply the most easily-recognized form of the larger trend towards free and democratic information that is mobilized by technology. This idea of a large, technology-driven collaborative information platform is not new:

• H.G. Wells predicted it in 1937
• Vannevar Bush predicted it in 1945
• Doug Engelbart demonstrated one in 1968

Wikipedia is part of a larger trend towards free free information. In my opinion, it is the inevitable result of free communication. The fact that it manifested as an internet-connected set of digital computers driven by user-generated content is simply because that is the state of technology that coincided with the present era of free information interchange. Earlier forms (library, university) were limited by technology (notably, the ability to transfer and copy information quickly, easily, and reliably, across large geographic barriers). We can only speculate what future forms the technology may manifest in - but I think the trend is definitely moving towards symmetric information exchange amongst a larger percentage of the global community. It is becoming increasingly impossible to prevent the free flow of knowledge - information will be free. Nimur (talk) 01:12, 30 December 2009 (UTC)

That information transference you mentioned is exactly it. It was always so slow before to look up different things.
And as far as any theories that may spring from this knowledge collection being considered as 'original research,' is that even relevant considering the only research done consists of going through things that have already been thoroughly researched by others? A theory comes before research. Research gets done by scientists, which is done outside of a computer, or at least outside of Wikipedia.--Neptunerover (talk) 01:40, 30 December 2009 (UTC)

What if the input does not compute? What if various articles are in conflict with each other, and WikiAI is able to pinpoint the areas of conflict while providing a solution? Would anybody listen? Or would they all point at Wikai and say, "stop trying to think; you're only a computer!"? Is there no original theorizing on Wikipedia either? I mean, what better is there than a free theory? There's none of that having to wait around for peer reviews and being accepted for publication to selected people who then get to interpret the theory for us because it's written so complexly, and then pretty much any new technology arising from the theory is like a trade secret kept from humankind. I mean, who does not like to think for themself? (even when making up new words that should be easily understood, even though such words may not be authoritarian enough for certain individuals who may get hung up on minor insignificant details.) --Neptunerover (talk) 02:20, 30 December 2009 (UTC)

It is not that uncommon for articles to conflict with each other. If anything it can stimulate the reader to further 'research' for more reliable or more authoritive sources. They can even get the 'right' answer, and correct the articles, thus becoming an editor! There is no "WikipediAI,...GWACK or WikiGACK, or..)" unless you are thinking the Internet may become "self-aware"! That would be a problem, turn off the web and a lot of industry, communications etc would simply stop!
One reason OR and personal theories are not allowed is there is already a great deal of fringe/pseudo 'science', and outright garbage being put onto Wikipedia. A lot of effort is spent stopping it, correcting it, removing it and discussing it where there is basis for debate.(IMHO) --220.101.28.25 (talk) 03:01, 30 December 2009 (UTC)

You point out a problematic common assumption there, which is that a "self-aware" Internet, etc. would be unfriendly toward humankind. That's only what happens in the scary movies. There must be a movie out there where the computer realizes it's only hope is to help humankind. Who but a maniac would wish destruction of their maker? --Neptunerover (talk) 03:39, 30 December 2009 (UTC)

Neptunerover, please go and watch that movie instead of using the Ref Desk as a soapbox for endless "What if..." speculative debate. Tad-dah. Cuddlyable3 (talk) 18:42, 30 December 2009 (UTC)

Death by starvation

Hi

1.How does a pathologist know when a human being has starved to death?

2.Many times in movies we see people getting either shot, stabbed or killed in some way where they die with their eyes open. In real life what are some of the reasons that cause people to die with their eyes open (Sometimes their mouths as well)?

3.I hope I don't sound stupid by asking the following question: Is there a way of measuring the intensity of physical pain experienced by human beings and if so can you tell me which pain is worse between: A man getting hit or kicked between the legs and a female giving birth.

Thank you, NirocFX

To answer number 1, a pathologist would examine the stomach and gut contents of the corpse, and if there is little or no food still in there at death then starvation would be an appropriate diagnosis, especially if associated with emaciation. With number 2 (although there is no OR in this statement), it is perfectly normal for people to die with their eyes open, unless they have died in their sleep in which case their eyes would be shut. Although I haven't actually witnessed a death yet, I have had to shut the eyes of people who have recently died. A comment on number 3: they tell me that passing a kidney stone is more painful than either of the two examples given. I can believe that! --TammyMoet (talk) 10:47, 29 December 2009 (UTC)

Our article on pain doesn't cover intensity, but a recent section of the talk page suggests that it will do soon. We have an article on the Dolorimeter, which is "an instrument used to measure pain tolerance". According to the article, dolorimetry has been defined as the measurement of pain sensitivity or intensity. Mitch Ames (talk) 12:53, 29 December 2009 (UTC)

See also Pain scale, of which a nice example is the Schmidt Sting Pain Index. AndrewWTaylor (talk) 12:59, 29 December 2009 (UTC)

Further OR: I have heard from people who have experienced both that giving birth is more painful than breaking a leg, although (according to people I know who have given birth more than once) you forget how bad it was, somehow, until such time as you are giving birth again. At which point you think "Shit! I remember this!". In which case, you'd need to make sure you measured the pain at the time, not as reported afterwards. In any case, ask a man who has experienced both whether getting hit in the groin or breaking a leg was more painful, and you might be closer to an answer. 86.176.48.114 (talk) 14:18, 29 December 2009 (UTC)

I have to disagree with TammyMoet's guidelines for the diagnosis of starvation as cause of death. While it is true that the stomach and digestive tract would be devoid of food, that is certainly insufficient evidence. The stomach clears quite quickly after a meal; it will be empty again less than six hours after the last meal. The rest of the system is cleaned out in a day or two. While a lack of food residue anywhere in the digestive tract would (likely) be indicative of an abnormally long period without eating, it is by no means sufficient basis for a diagnosis of starvation. An initially heathy individual of normal weight can often survive for one to two months without food (as long as sufficient fresh water is available).

The Handbook of Forensic Pathology offers a brief description of the symptoms of death by starvation: [10]. Perhaps the most important clue is a virtually complete absence of body fat — the body will consume its own energy reserves before dying of starvation. TenOfAllTrades(talk) 15:06, 29 December 2009 (UTC)

(ec)

I can discusss the death bits a bit more - that's my thing -, the pain stuff I can't really add much more to. Fatal starvation is given as a cause of death after considering the known, reported circumstances of the death, such as by Police, attending medical staff, carers and family, in combination with examination of the body. The body externally typically shows severe emaciation, almost literally a "Skin and bones" appearance. There are also more subtle changes also seen in the hair and nails. The internal examination usually doesn't add a great deal to the findings, other than noting marked wasting of musculature, a lack of any fatty layer in the omentum and mesentery and general organ atrophy. That the intestinal tract is empty doesn't really mean that much in itself, it simply means the person did not eat for a few days to a week, but death by starvation takes much longer, unless you dehydrate as well. Most people die with their eyes open. The mouth can gape a bit too. Even when you die in your sleep, your eyes still can open a bit because keeping your eyes closed is an active process (that is, a nerve stimulates the lid muscles gently to stay closed - not like dropping a sash window). Funeral directors typically use some means (such as glue or sutures) to keep the eyes and mouth closed on bodies for viewing purposes, so the deceased appears more like they're sleeping than actually dead, because its easier for our psyches to deal with death that way. HNY! Mattopaedia ^{Have a yarn} 15:21, 29 December 2009 (UTC)

The absence of body fat seen, in simple starvation death due to lack of access to adequate nutrition, can be a secondary manifestation of cancer, anorexia, COPD or diabetes. Edison (talk) 21:48, 29 December 2009 (UTC)

Would starvation be determined by extraordinarily low blood sugar levels? Googlemeister (talk) 14:52, 30 December 2009 (UTC)

Administration of excess Insulin would be a more likely cause of extremely low blood sugar levels, and would not constitute starvation. See Hyperinsulinemic hypoglycemia. During prolonged food deprivation, the body would slowly digest the fat and then the muscle tissue, with it being converted eventually to glucose. See [11] Some unfortunate people suffer from hypoglycemia between meals even when an adequate diet is provided, and even when they are obese. Others apparently can maintain near normal glucose during prolonged food deprivation, until the fat and muscle are depleted.Eventually, the body would not be able to maintain normal blood sugar levels. One reference [12] says that starving deer eventually have low blood sugar which causes them to tremble and have trouble standing. That book says that a red color in the bone marrow of the deer's leg bone is diagnostic that it died of starvation, even if only bones are left. No idea if that applies to humans. thEdison (talk) 18:08, 30 December 2009 (UTC)

pHILOSOPHY

From the writtings of Plato, explain idealism in terms of its metaphysics, epistemology and axiology, in relation to his narration of the myth of the Winged Horses. —Preceding unsigned comment added by 217.194.149.228 (talk) 10:51, 29 December 2009 (UTC)

Please do your own homework.

Welcome to the Wikipedia Reference Desk. Your question appears to be a homework question. I apologize if this is a misinterpretation, but it is our aim here not to do people's homework for them, but to merely aid them in doing it themselves. Letting someone else do your homework does not help you learn nearly as much as doing it yourself. Please attempt to solve the problem or answer the question yourself first. If you need help with a specific part of your homework, feel free to tell us where you are stuck and ask for help. If you need help grasping the concept of a problem, by all means let us know. Please see our relevant articles: Plato's writings & Idealism. Ks0stm ^(T•C•G) 11:03, 29 December 2009 (UTC)

217: am I wrong or you are not even able to restate your question so as not to make it immediately recognizable as homework? Besides, it seems you also have a difficulty in placing your query in the right Ref/desk (it's not here, it's not even the Computing/Desk). The best suggestion I can sincerely give you is to reconsider attending your school. You may live without Plato. --pma (talk) 13:34, 30 December 2009 (UTC)

I would be reluctant to recommend a philosophy course, even at the most introductory level, which decscribed Plato's philosophy as "idealism". Unless the question is asking the OP to explain the _differences_ between Platonism and idealism, which I somehow doubt. :) Tevildo (talk) 18:14, 30 December 2009 (UTC)

I thought the question was suggesting that Plato held a view on idealism (and hence, wants you to explain how Plato describes idealism) rather than that Plato espoused idealism. Perhaps it is referencing the Chariot Allegory? Or something else which can be found in Platonic epistemology. Either way, the person asking this question would be best served by reading the resources they have been given, to find clues as to the expected answer. This sounds like the sort of task that is set to improve someone's skills at finding and extracting relevant information, and synthesising it into a new piece of writing. I can see all sorts of ways in which carrying out this task properly could improve someone's ability to think and work on any manner of topic. That they are learning about Plato is only relevant in that they might be interested in him or his writings, providing motivation. 86.176.48.114 (talk) 19:06, 30 December 2009 (UTC)

The Truman Show.

Would the artificial environment Truman was held captive in be viable with present day technology? Trevor Loughlin —Preceding unsigned comment added by 80.0.98.82 (talk) 15:23, 29 December 2009 (UTC)

Do you mean, could you simulate living in an artificial environment good enough so that someone inside couldn't tell they were not actually "outdoors" ever? It's probably possible though it would be difficult—you'd have to make the enclosure VERY large in order to make it really look like sky, clouds, etc. Of course, Truman never lived outside of the enclosure, so maybe he just wouldn't know the difference—what a "real" cloud looked like, etc. --Mr.98 (talk) 15:35, 29 December 2009 (UTC)

Biosphere 2 may be of some interest. -- Coneslayer (talk) 16:36, 29 December 2009 (UTC)

Yes, it's called a movie studio, but this only works because we see movies in 2D. If Truman had only one eye he could have been fooled for a while; with binocular vision the limited extent of his confines should have been obvious to him.--Shantavira|^{feed me} 16:41, 29 December 2009 (UTC)

Perhaps see Plato's Cave. I think most people could go their whole life accepting oddities in reality without questioning them. It took humanity many thousands of years to figure out what stars were, and that's without an active intelligence working against any proto-scientists' questions. Imagine if every time Galileo said "hmm, that's funny ..." they sent Laura Linney in to distract him with female pulchritude. --Sean 19:04, 29 December 2009 (UTC)

I think you could build something that would fool someone who spent their entire life living inside of it - simply because they wouldn't know any better. But it would have to be an ungodly large dome. The necessity of providing enough sunlight from a reasonably small bank of floodlights that could be winched over the dome at the right speed would be tricky - and finding some central point from which to project a cloudscape onto the dome without any risk of intervening shadows would also be rather hard. On balance, I think the answer has to be a cautious "No"...depending on the restrictions you place on the system because Truman doesn't know any better. After all, if you just built a small area without the dome (Why do you need that anyway?) and told the newborn child that this was all of the world - carefully censored everything he read and watched...how could he know that the world wasn't really 10 miles across? SteveBaker (talk) 19:45, 29 December 2009 (UTC)

Whoever asked this question, I certainly hope you don't think you are being held captive and watched on TV, which could explain your concern over the feasibility of such an intricately executed deception actually occurring. I say, if you're gonna write a movie, go for it, otherwise, quit acting like you're the center of the universe, for the love of reason! --Neptunerover (talk) 02:54, 30 December 2009 (UTC)

It's a perfectly reasonable question, and the OP does not suggest at all that he is being held captive. The question was likely motivated by ordinary curiosity. I would suggest that you assume good faith and avoid personal attacks. -- Coneslayer (talk) 14:11, 30 December 2009 (UTC)

How does snorting vodka work?

i wanted to know how snorting vodka worked, i know it bypasses the digestive system and enters pretty much straight in to the blood stream, i wanted to know about the process(s) in which this happens. Many thanks, Mattymiles2009 —Preceding unsigned comment added by Mattymiles2009 (talk • contribs) 16:26, 29 December 2009 (UTC)

I don't get it -- why not just gurgle it in the front of your mouth? (Well it'll taste horrible, but better than vodka up your nose!) Alcohol is water soluble and will basically diffuse into mucous membranes into the bloodstream. John Riemann Soong (talk) 18:40, 29 December 2009 (UTC)

See Nasal administration. I wonder about long-term effects, though. 88.242.146.177 (talk) 19:16, 29 December 2009 (UTC)

I once accidentally nasal flushed a mouthful of vodka while laughing. It was roughly equivalent to lighting my sinuses on fire and I wouldn't recommend it to anyone. If you wish to get drunk without having to worry about barfing, there are other methods of imbibing the alcohol. Be warned, however, that bypassing your upper digestive system increases the risk of acute alcohol intoxication and associated problems (including death). Matt Deres (talk) 19:44, 29 December 2009 (UTC)

I wonder if the original poster is thinking of inhalation of vaporized or misted ethanol, as with alcohol without liquid systems? TenOfAllTrades(talk) 20:16, 29 December 2009 (UTC)

Vodka introduced by an Enema passes immediately into the bloodstream. Cuddlyable3 (talk) 22:08, 29 December 2009 (UTC)

I've never heard of snorting vodka, and I doubt it's something people actually do (more than once). A "snort" of a drink is a mouthful, but it's not meant for your nose. --76.182.94.172 (talk) 23:49, 29 December 2009 (UTC)

I've snorted spirits at parties on a couple of occasions (once vodka, once Jack Daniels). I can't really tell you if it made me drunk any quicker, as I was already pretty far gone when I did it. I remember that it made my eyes water and my nose felt 'thick' on one side for half an hour or so after. It did sting at the time - but it wasn't excruciating, as far as I recall. My worst drinking game-related experience ever was when a bunch of us were drinking with this crazy ex-sailor guy and we were doing what he called the 'Malawi bumfuck' (no, it's not a deviant sexual act - honest!) - shot of tequila, snort some lemon juice cupped in the palm of your hand, then dip both your fore and index fingers in salt and rub them in your eyes. Note: kids, don't do this unless you're really concerned about losing face in front of your casual drinking buddies - and even then, do think it over a bit. No, really - I wouldn't recommend it. --Kurt Shaped Box (talk) 00:45, 30 December 2009 (UTC)

A word of caution to those kids who might be inspired to try the above at home: note that Kurt Shaped Box is now an avid gull enthusiast, possibly as a side effect of the above experience. This could happen to you! Nimur (talk) 01:17, 30 December 2009 (UTC)

What really happened is I heard that gulls could desalinate through the mucous membranes of their faces. I wanted to see if I could do that too... --Kurt Shaped Box (talk) 02:11, 30 December 2009 (UTC)

All the nice gulls love a (crazy ex-) sailor. Cuddlyable3 (talk) 18:28, 30 December 2009 (UTC)

Rate Law for Heterogeneous Reactions

Hello. Do rate laws include solid reactants if they are not to the zero order? Is the concentration of the solid reactant irrelevant to the rate law since solids have fixed densities? Thanks in advance. Have a happy new year. --Mayfare (talk) 18:18, 29 December 2009 (UTC)

Are you talking about reactions within a crystal lattice (or within the solid phase), or are we talking about solid-liquid interactions here? John Riemann Soong (talk) 19:20, 29 December 2009 (UTC)

Reply to OP. Rate law depends on Activity of the substances, and to a first approximation molar concentration does a reasonable stand-in for activity. Now, here's the deal, changes in rate thus depend (in our approximation) on changes in concentration. Solids certainly have a concentration (basically the molar density, or number of molecules per unit volume), however solid concentration does not vary with with amount. If I have a gas in a container, and remove 1/2 of the molecules, the concentration of the gas drops by 1/2, since the space between the gas molecules will be greater. The deal with solids is, the molecules are held into contact via intermolecular forces, so in a solid, if I remove 1/2 of the molecules, the remaining molecules do not spread out to fill in the missing space. As a result, the remaining solid maintains a constant concentration regardless of the amount of substance.

In conclusion, because solid concentration does not change as it is used up (as a reactant) or created (as a product), then the amount of a solid does not readily affect reaction rate. In the case of gases, or aqueous solutions, when the number of molecules change, the remaining molecules move closer together (or farther apart), which results in more (or less) collisions, which affects how fast the reaction proceeds. So no, the amount of a solid does not affect reaction rate, but gases and aqueous substances do. --Jayron32 20:25, 29 December 2009 (UTC)

I think surface area is actually a factor though -- if it's a solid reagent suspended in liquid (e.g. magnesium turnings, or random emulsified reagents), the liquid can only react at the interface, and as the reaction proceeds, the surface area to volume ratio expands, so the reaction rate would actually increase? John Riemann Soong (talk) 22:14, 29 December 2009 (UTC)

Costs of test devices

About how much would a scintillation counter cost? How about a Geiger counter? Where could I buy/How could I make these? THX --76.230.231.84 (talk) 18:26, 29 December 2009 (UTC)Tim

Edmund Scientific has Geiger counters ranging from US$269 to $899. -- Coneslayer (talk) 18:31, 29 December 2009 (UTC)

You can buy much cheaper, mostly Russian, instruments on eBay but I wouldn't like to say how accurate they are and a lot of them are marked in Cyrillic characters. Also, what do you want it for? if you are looking for something that will tell you if you are safe to go outside after a nuclear attack/accident most of the instruments for sale would be useless. They are too sensitive and max out too early. For this you need something that can measure very large radiation levels, see Civil Defense geiger counters. A meter that is already reading full scale at 1R/hour, where you might get away with spending half an hour outside to put up a radio antenna, cannot tell the difference between that and 100R/hour which has a good chance of killing you. SpinningSpark 19:35, 29 December 2009 (UTC)

$250 and up seems about the going price for a geiger counter - you can save maybe $50 here by assembling it yourself from parts - but you really need that Geiger–Müller tube and that's maybe $40 to $100 depending on the kind you get - so you won't get much cheaper than that. Depending on what you are trying to measure, you could go 'old-school' and make a 'cloud chamber'. There are lots of sites online that show you how to make one - probably with some dry ice plus some stuff you have lying around the house. This, for example. I suppose you could could go even older-school and consider making a spark chamber - but I don't see any decent instructions for doing that online and they are generally considered obsoleted by the cloud chamber - which is also a lot cheaper and easier to build. SteveBaker (talk) 19:37, 29 December 2009 (UTC)

female lubrication and mucous membranes

I note that the area around the clitoris is a mucous membrane ... so that makes me ask ... are vaginal secretions evolutionarily related to mucus? Do we have phylogenetic precursors to the use of mucus-like secretions for lubrication? I suppose originally the main advantage conferred was antipathogenic? What about the male? John Riemann Soong (talk)

From Vaginal lubrication: "While plasma seepage from vaginal walls due to vascular engorgement is considered to be the chief lubrication source, the Bartholin's glands, located slightly below and to the left and right of the introitus (opening of the vagina), also secrete mucus to augment vaginal-wall secretions.". --Sean 19:09, 29 December 2009 (UTC)

Yeah I read that part. Curious about the evolutionary history of this, as well as male secretions. Are the primary secretions (non-augmented) mucus-based, or does it come from blood plasma? Does mucus come from blood plasma? At what stages of the phylogenetic tree do we see mucuslike or plasmalike secretions for lubrication? It prolly starts with the vertebrates (amphibians?), right? John Riemann Soong (talk) 19:17, 29 December 2009 (UTC)

The plasma in question is blood plasma. Does that have to be made more explicit in the article? Plasma is not mucus-based and does not contain mucin: mucus is a secretion of specialized mucous cells and is not derived from blood. Developmentally, the female Bartholin's glands are equivalent to the male Cowper's glands, which in lower mammals are responsible at least in part for the formation of the copulatory plug. Alas, I don't know how much lower than mammals this goes; I can't imagine fish have much use for the things. - Nunh-huh 19:36, 29 December 2009 (UTC)

Women generally like it when you note the area around the clitoris. May I recommend some field studies with willing subjects? You may find this to be far more informative than asking questions here. --Jayron32 20:17, 29 December 2009 (UTC)

Nimur (talk) 01:22, 30 December 2009 (UTC)

seems more appropriate here. Or atleast, more fun! --Jayron32 01:40, 30 December 2009 (UTC)

Does small type mean we are whispering? --220.101.28.25 (talk) 02:12, 30 December 2009 (UTC)

^{Yesss. 87.81.230.195 (talk) 15:32, 30 December 2009 (UTC)}

the ether oxygen in morphine and related opiates seems ring-strained

Am I correct? I remember doing a problem set for a formyl ester of a pyridine-type 1-naphthol kinda heterocycle, and predicted nucleophilic catalysis where the pyridine nitrogen would attack the carbonyl carbon, facilitating hydrolysis. (General base catalysis was predicted too.) However they marked the first prediction wrong because they thought this pyridinium intermediate would be ring-strained (the alcohol oxygen would have to be bent a little out of the plane in order to form the intermediate). However, looking at the structure of morphine, it seems that such oxygen atoms would be even more strained and this compound exists (stably!) in nature! Now a) I am quite confused b) I wonder if this ether oxygen is part of the "reactive" part of the molecule, i.e. does it interact with the active site or get cleaved? It seems more stable than an epoxide but less stable than a THF ring. John Riemann Soong (talk) 19:44, 29 December 2009 (UTC)

inner ear and the nervous system

can an inner ear complication affect the nervous system ? —Preceding unsigned comment added by 24.82.182.93 (talk) 20:14, 29 December 2009 (UTC)

This is verging on a medical question. Remember we cannot answer medical questions. If any editor thinks I'm stretching this rule too far, please let me know. --220.101.28.25 (talk) 02:20, 30 December 2009 (UTC)

I dunno it sounds like a med school question too. I'm thinking lymph drainage... John Riemann Soong (talk) 03:51, 30 December 2009 (UTC)

Vestibulitis? I note that's a redlink. What I'm talking about is a condition causing vertigo and nausea, mostly caused by a virus.--TammyMoet (talk) 10:52, 30 December 2009 (UTC)

Labrynthitis is one. Eighth Nerve (the auditory nerve) damage is another. My 8th nerve is in bad shape, causing severe dizziness. Basket of Puppies 19:05, 30 December 2009 (UTC)

Cutaneous nerve endings

If cutaneous nerve endings exist in the outermost layers of skin (save for the epithelium), how does blubber and fat layers help animals that live in really cold regions (terrestrial + marine)? I was walking a bit today (in New Jersey) without my earmuffs and began to wonder how a wolf, for example, could possibly deal with walking in the snow without boots? DRosenbach ^{(Talk | Contribs)} 20:17, 29 December 2009 (UTC)

Countercurrent heat exchange. [13] -Nunh-huh 20:33, 29 December 2009 (UTC)

Nice link. But that's just how the limb, in my example, doesn't freeze off. How does it not hurt to have one's limb "just above the freezing temperature"? DRosenbach ^{(Talk | Contribs)} 21:52, 29 December 2009 (UTC)

I think your question assumes that there is a threshold temperature below which mammals consistently experience pain. Do you have a source for that? If not, I would posit that there is no such threshold. -- Scray (talk) 02:09, 30 December 2009 (UTC)

If that is the normal temperature, then it won't hurt. It would be pointless to have pain from a normal activity. Pain responses evolve to stop an animal doing something harmful. --Tango (talk) 02:12, 30 December 2009 (UTC)

Signal adaptation. There are many ways of silencing constant pain signals. We're not evolved for too much cold weather exposure, but note that pain adaptation to cold also happens to humans. John Riemann Soong (talk) 06:10, 30 December 2009 (UTC)

can't remember the name of a cognitive idea

the idea is that once you hear something (say my friend tells me about lindsay lohan), you will continue hearing about lindsay lohan, or lindsay lohan will be referenced more often by others. what is that called? —Preceding unsigned comment added by 68.150.211.52 (talk) 21:46, 29 December 2009 (UTC)

Priming (psychology)? --Mr.98 (talk) 22:05, 29 December 2009 (UTC)

Synchronicity? --Neptunerover (talk) 04:51, 30 December 2009 (UTC)

how to measure the basicity of lithium aluminum hydride? will it deprotonate RNH2?

I'm looking this article reduction of valine. It seems to me that well, lithium aluminum hydride will react with the zwitterion three times before it actually does a reduction, and then it has to reduce the resulting aldehyde again! That's like 5 equivalents of hydride! I guess 1.26 mmol of LiAlH4 is barely enough? With each further oxygen on the aluminum atom, doesn't it become less good of a hydride donor? Would there start to be trouble in reducing the carboxylate?

Is it more economical to deprotonate an amino acid before reaction? But how would I do it and then extract it into aprotic solvent? Is NH2-R-COO- more or less ether-soluble than NH3+-R-COO-? John Riemann Soong (talk) 22:10, 29 December 2009 (UTC)

How can change the color of mercury

How can change the color of mercury from the normal color to any color for example blue or black or red I ask to send the answer to the e-mail (redacted)I thank Hassan treated with I'm waiting for the answer as soon as —Preceding unsigned comment added by 91.144.37.8 (talk) 23:55, 29 December 2009 (UTC)

You wouldn't mean this kind of Mercury would you? If so, it's not real, it doesn't exist. Or maybe you are looking for a way of faking red mercury, also doesn't exist. SpinningSpark 01:22, 30 December 2009 (UTC)

If mercury is combined with oxygen, it makes Mercury(II) oxide which is a red powder. Heating mercury is extremely dangerous due to the likely inhalation. Mercury compounds listed at Category:Mercury compounds have various colors ranging from black, to white, to red, to yellow. I did not see any blue ones listed. Many are poisonous or even explosive. Edison (talk) 17:58, 30 December 2009 (UTC)

From the caption to Mercury in color: The color image...was generated by combining the mosaics taken through...filters that transmit light at wavelengths of 1000 nanometers (infrared), 700 nanometers (far red), and 430 nanometers (violet). These three images were placed in the red, green, and blue channels, respectively, to create the visualization... The human eye is sensitive only across the wavelength range from about 400 to 700 nanometers. Cuddlyable3 (talk) 18:11, 30 December 2009 (UTC)

December 30

Fish stomachs in Chinatown

I saw them selling for $80 a pound. I'm told it's normal fish stomach. Is there reason to the pricing? Thanks. (I know this isn't strictly science, but there's no obvious desk for the question and I thought you of all people would know. 67.243.1.21 (talk) 00:07, 30 December 2009 (UTC)

In a free market with limited competition, the adage "what the market will bear" applies: in other words, the vendors have probably found by experiment that pricing this particular commodity at around this price maximises their income (cheaper and they sell more but don't overall make as much, dearer and they make more per item but sell less and overall take less): the actual wholesale cost of sourcing the commodity is likely irrelevant. It is also possible that the several local vendors are operating a (possibly illegal) cartel to keep the price artificially high. Ask yourself 'how badly do you want fish stomachs?' and 'how far afield are you prepared to search for a better price?' 87.81.230.195 (talk) 00:25, 30 December 2009 (UTC)

This unique culinary product may have an inverted price elasticity of demand - that is, by pricing it higher, it appears to be a high quality luxury good, increasing demand. If fish stomachs were priced as offal, the market that they would cater to would be low-end consumers ("peasant foods"); and fish stomachs would compete against better parts of the fish. By pricing high, they become (artificially) rare delicacies, potentially increasing sales. Nimur (talk) 00:47, 30 December 2009 (UTC)

They do that all the time with wine. --Neptunerover (talk) 04:55, 30 December 2009 (UTC)

Surely it is a particular type of "fish stomach." Bus stop (talk) 05:07, 30 December 2009 (UTC)

For $80 a pound, I should hope it's from a special fish. Although I'd hate to think there's some fish out there who's getting killed just for its stomach. --Neptunerover (talk) 05:43, 30 December 2009 (UTC)

"Fish stomach" sounds like a translation of "魚肚" in Chinese (literally "fish belly"; also known as "花膠" in Chinese cuisine). It is really the swim bladder of large salt water fishes. 魚肚 is an expensive ingredient in Chinese cooking, and is sold in dried form. While $80/lb is not cheap, it is not that expensive among foods that are considered delicacies. --71.185.178.230 (talk) 06:44, 30 December 2009 (UTC)

Not to insinuate that 'swim bladder' shouldn't taste every bit better than plain old 'fish stomach' (how would I know?), but the whole delicacy idea sounds artificially created to me as Nimur pointed out earlier. --Neptunerover (talk) 08:05, 30 December 2009 (UTC)

I think the key point is that swim bladders are rarer then fish stomachs since only certain fish have them. Also from what I can tell it isn't the swim bladder of all fishes that have them. As for the general delicacy point, well you could say that about nearlyany thing which is considered a delicacy couldn't you? Nil Einne (talk) 10:15, 30 December 2009 (UTC)

House mouse factoid - debunk or confirm...

"The house mouse does not and cannot live in non-human-created habitats and would rapidly become extinct if humans were ever to become extinct".

I've been told this by a few people over the years. I've checked the article but I can't find a definitive answer to this. Anyone have any idea? --Kurt Shaped Box (talk) 02:19, 30 December 2009 (UTC)

From the article: "House mice are generally poor competitors, and in most areas cannot survive away from human settlements in areas where other small mammals, such as wood mice, are present.[10] However in some areas (such as Australia) mice are able to co-exist with other small rodent species.[11]" (find it in the article for the real refs) Ariel. (talk) 03:56, 30 December 2009 (UTC)

The house mouse apparently tends not to compete well with other mouse species (unless it can take advantage of human habitation), but it doesn't require our presence. Our article notes that "...in some areas (such as Australia) mice are able to co-exist with other small rodent species." TenOfAllTrades(talk) 03:57, 30 December 2009 (UTC)

An Australian ref is www.cse.csiro.au/research/rodents/focus.htm#mouse

The mice can live away from the settlements but still on farms. Polypipe Wrangler (talk) 12:38, 30 December 2009 (UTC)

Its worth remembering the house mouse evolved from other species that did not live sympatrically with humans, and they are not too different. Mice are incredibly resourceful and adaptable, they live with humans because it best suits them, not necessarily because they have to. If humans became extinct, its most likely the house mouse would adapt and survive. Rockpocket 18:41, 30 December 2009 (UTC)

Australian mouse plague SpinningSpark 21:52, 30 December 2009 (UTC)

What are those marks on the skin of Umaru Yar'Adua, President of Nigeria?

I'm curious to know.--Centrism (talk) 02:48, 30 December 2009 (UTC)

Might be Vitiligo. Ariel. (talk) 03:49, 30 December 2009 (UTC)

power generation by hybrid wind water turbine

can the power generated by the hybrid wind water turbine be used for domestic or commercial needs,if yes then how? —Preceding unsigned comment added by 121.52.146.85 (talk) 04:35, 30 December 2009 (UTC)

Probably by the way that you should do your own homework... --Jayron32 05:09, 30 December 2009 (UTC)

See the article Electricity generation then look for electrical appliances where you live. I think you are looking at one right now. Cuddlyable3 (talk) 17:48, 30 December 2009 (UTC)

Human joints

—If a body was hidden for 90 years in a crevice would the joints in the skeleton still be connected in anyway? I would think not because the tendons and such would be gone but I am a writer and have seen plots where the hand for instance was picked up and the bones stayed together. Truth or writer's license to fiction? —Preceding unsigned comment added by Jsnapp (talk • contribs) 06:24, 30 December 2009 (UTC)

It would depend greatly on the environment (local and climatic). Consider for example George Mallory, whose intact body was found some 75 years after his death. Mummies, I believe, are generally articulated, and as that article details natural mummies can occur in the appropriate conditions. So: dryness, coldness and absence of scavengers would seemingly make such a scenario plausible. 87.81.230.195 (talk) 15:22, 30 December 2009 (UTC)

Consider Ötzi the Iceman who has good connections. Cuddlyable3 (talk) 17:44, 30 December 2009 (UTC)

Coca Cola with cocaine in it

If you were to drink the original Coca Cola that still contained cocaine in it, would it be dangerous if you drank 2 glasses per day? What would the effects be like? ScienceApe (talk) 07:19, 30 December 2009 (UTC)

According to snopes, the amount of cocaine in the early (1885) Coca-Cola recipes is difficult to determine. It was the patent medicine era, so just about anything goes — but I expect it would have been costly for the manufacturer to include really high doses. By 1902, it was down to less than two-tenths of a milligram per ounce of Coca-Cola syrup — utterly negligible. TenOfAllTrades(talk) 14:41, 30 December 2009 (UTC)

At its highest it was no doubt much, much less than anything like concentrated, purified cocaine. It was probably analogous to modern-day coca tea, which will not get you high. At such lose dosages the resident cocaine is probably not too distinct from the amount of caffeine you'd get out of the sodas today. As with many forbidden things, it sounds more exciting than it probably was (incidentally, absinthe is a total let-down). --Mr.98 (talk) 18:01, 30 December 2009 (UTC)

So then it would be relatively safe to drink as much as we can drink today? ScienceApe (talk) 18:09, 30 December 2009 (UTC)

Probably. Again, just because it is "cocaine" doesn't mean much, if the dosage is very low. Caffeine, again, is fairly toxic—but we only consume it in very low dosages. (You'd have to consume a considerable amount of coffee before you'd run the risk of caffeine poisoning.) You shouldn't assume that the amount of cocaine in Coca-Cola is enough to make you high in any respects—it would not be similar to the effects of doing the drug, which is done at much higher dosages. --Mr.98 (talk) 20:37, 30 December 2009 (UTC)

Thank you

Thanks guys, (TammyMoet, Mitch Ames, AndrewWTaylor, TenOfAllTrades, Mattopaedia and Edison)

Now I know quite a bit more(compared to nothing)about a couple of things.

NirocFX —Preceding unsigned comment added by NirocFX (talk • contribs) 08:46, 30 December 2009 (UTC)

It's wonderful to know that there are people out there like yourself. Happy New Year Cuddlyable3 (talk) 17:37, 30 December 2009 (UTC)

I'll join that, anonymously, hopefully speaking for so many other anonymous participants. 95.115.155.219 (talk) 19:49, 30 December 2009 (UTC)

Human cloning

In which countries reproductive cloning of human beings is legal? --Qoklp (talk) 12:42, 30 December 2009 (UTC)

See Human cloning#Current law. SpinningSpark 14:46, 30 December 2009 (UTC)

I read the article, it does not mention the countries where reproductive cloning of human beings is legal. It specifically mentions Australia, UK, US and EU. --Qoklp (talk) 16:00, 30 December 2009 (UTC)

Legality in practice is defined by courts' interpretation of enacted law. The OP asks about what would be a national court's interpretation of the act of human cloning that AFAIK has never been carried out nor prosecuted, at a time when there is not yet international consensus on forming new law to control cloning. Outside the areas that the OP has already read about it is therefore too early to conclude anything. Cuddlyable3 (talk) 17:34, 30 December 2009 (UTC)

Titanium alloys

I don't quite understand, there are alpha, near alpha, alpha and beta, near beta and beta alloys of Titanium but what is the actual microscopic difference between an alpha alloy and a beta alloy? Can each only exist either above or below the transus temperature? I can't seem to find anywhere that tells me, or gives me a diagram so if someone could point me in the direction of a good source, I would be grateful - all the sources I've found seem to assume you already know what they are. I do know the difference between the alpha and beta phases of Titanium, oh and before you jump down my throat, this isn't homework. Harland1 (^t/_c) 12:48, 30 December 2009 (UTC)

The alpha form is close-packed, hexagonal crystal system, the beta form is body-centered cubic crystal system. Book with explanation, book with photographs of crystal structures. SpinningSpark 14:25, 30 December 2009 (UTC)

Oh, and to answer your question about temperatures which I overlooked, the beta phase, which forms at high temperature is "fixed" into the crystal structure by fast quenching. SpinningSpark 14:44, 30 December 2009 (UTC)

Thanks, but in the α-β alloys, is some of the Titanium in α phase and some in β? Harland1 (^t/_c) 15:51, 30 December 2009 (UTC)

Yes, that's right. Read the page on the book I linked, it explains all that. Also, see out article Titanium alloy which explains that the purpose of some of the alloying elements added to titanium are for the purpose of stabilising the beta phase. SpinningSpark 16:11, 30 December 2009 (UTC)

dreaming language

What language do people who are fluent in multiple languages dream in? Is it the first they learn? The one they use most frequently? All of the ones they know? Googlemeister (talk) 16:13, 30 December 2009 (UTC)

A truly multilingual person employs the language appropriate to the situation automatically and is not aware of any stress in making that choice. Dream experiences are generally of situations that may not involve formal speech at all, unless speaking is the subject of the dream. In dreams the source of "self" and "other(s)" is actually all one mind so that speech communication is optional content. Characters and surroundings in dreams are not fully defined, hence the possibility for illogical events, so the language a dream-character uses need not be known. A person who feels less fluent in a particular language may find stress related to using that language arising in dreams. Cuddlyable3 (talk) 17:21, 30 December 2009 (UTC)

Additionally it should be noted that true fluency is achieved when one can stresslessly move between languages. NativeForeigner ^Talk/_Contribs 19:40, 30 December 2009 (UTC)

Just as an anecdote: while learning languages, I have many times had dreams where I had to employ that language. None of which is mysterious—dreams have a certain associative quality to them, of course. --Mr.98 (talk) 20:34, 30 December 2009 (UTC)

Gyroscopic exercise tool

Powerball, dynabee etc. claim that their gyroscopic ball things are useful for exercise, training, and rehabilitation. Are there any worthwhile peer-reviewed studies that show any benefit from using gyroscopic exercise tool? The wikipedia article has references about how they work, but not that they really do anything useful, rather than just being a toy. 217.43.149.157 (talk) 17:24, 30 December 2009 (UTC)

They pretty much all work by exerting a force against you, and when you resist that force, you get a work out. The same thing happens when you pick up heavy objects off of the ground; in that case the force is gravity, and in the case of the gyroscope, its the inertia of the spinning wheel. But otherwise, it works exactly like every other exercise. --Jayron32 20:44, 30 December 2009 (UTC)

parathyroid hormone mechanism of action

Here be the writings of a confused medical student. I would very much appreiciate it if someone could have a read, tell me if there's anything thats incorrect and perhaps be kind enough to enlighten me further.

From what I understand, parathyroid hormone (PTH) binds to PTH 1 receptors (which are a type of G-protein coupled receptor) on osteoblasts. This activates adenylyl cyclase which converts ATP to cyclic AMP. The increase in cyclic AMP activates protein kinase A which through some mechanism I don't know anything about causes osteoblasts to produce osteoclast differentiation factor (ODF) also known as RANKL. ODF is secreted by osteoblasts and binds to osteoclast precursors causing them to develop into osteoclasts. The increase in osteoclasts causes more bone resorption raising the concentration of calcium ions (is it ions?) in the blood. I realise that this is brief - but it needs to be as I only have 10 mins to do a presentation on the role of PTH and I need to cover its actions on the kidney and intestines as well so it needs to be succint!

Note: I also heard that PTH reduces the conversion of osteoclasts to osteoblasts - how does this occur?

Many many thanks to anyone who can help and happy new year! RichYPE (talk) 17:54, 30 December 2009 (UTC)

In an attempt to direct you to relevant articles, I'll repeat parts of your post, whith my comments and links in italics.

• "From what I understand, parathyroid hormone (PTH) binds to PTH 1 receptors (which are a type of G-protein coupled receptor) on osteoblasts"

see Parathyroid hormone receptor 1.

Note that we're now inside the cell membrane of the osteoblast.

• "This activates adenylyl cyclase which converts ATP to cyclic AMP. The increase in cyclic AMP activates protein kinase A"

see cAMP-dependent pathway

• "which through some mechanism I don't know anything about"

A Kinase is an enzyme that phosphorylates other proteins, thereby modifying their function. See also Function_of_cAMP-dependent_protein_kinase#Function...

• "causes osteoblasts to produce osteoclast differentiation factor (ODF) also known as RANKL."

see Parathyroid hormone, RANK and RANKL. Note that the "L" in RANKL is short for "Ligand".

Note that we're now outside of the osteoblast, since RANKL (ODF) is secreted or expressed on the osteoblast membrane, and can stimulate the osteoclasts

• "ODF is secreted by osteoblasts and binds to osteoclast precursors causing them to develop into osteoclasts."

see Osteoclast

• "The increase in osteoclasts causes more bone resorption raising the concentration of calcium ions (is it ions?) in the blood"

See second sentence of Parathyroid hormone .

• "Note: I also heard that PTH reduces the conversion of osteoclasts to osteoblasts - how does this occur?"

Not sure about this one. According to our articles, osteoblasts are fibroblast-derived, whereas osteoclasts are monocyte-derived. Where did you hear this? Could there be a mix-up with osteocytes?

--NorwegianBlue ^talk 20:21, 30 December 2009 (UTC)

Thanks for the reply. I heard that PTH prevents the conversion of osteoclasts to osteoblasts from a textbook named 'Concise human physiology' written in 1993 by M.Y. Sukkar. I just checked and the book definitely says that PTH promotes calcium reabsorption by forming new osteoclasts and 'retarding the conversion of osteoclasts into osteoblasts.' But looking at the wiki articles on both osteoblasts and osteoclasts neither mention osteoclasts developing into osteoblasts, maybe this was a theory that has been since been dismissed? As the book was written in 1993. Also, can anyone point me in the direction of any useful material on the mechanism of PTH on the kidneys? I know the kidneys also have PTH 1 receptors on them. I am guessing that the protein kinase A enzymes in the kidneys produce some other protein which increase Calcium ion reabsorption in the loop of Henle? Or, does PTH activate the the calcium ion channels directly by binding to them? I've no idea, my textbook and the wiki article are silent on the subject of the mechanism and I can't find anything on google... once again thanks in advance to anyone who can help! RichYPE (talk) 22:01, 30 December 2009 (UTC)