Wikipedia:Reference desk/Archives/Science/2007 October 13

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October 13

Robotic Arms

Has anyone come up with a way to make robotic tentacles? That is, long, everywhere-articluated arms like an octopus or snake? Black Carrot 01:56, 13 October 2007 (UTC)

Yes. Did you even try to Google for robotic tentacle? -- kainaw™ 02:47, 13 October 2007 (UTC)

I knew I'd forgotten something. I did check Wikipedia itself for it (and ran into some serious stubs). Thanks. 76.185.123.122 03:04, 13 October 2007 (UTC)

Make that an image-search and you get some intriguing ideas of what one could do with such tentacles. DirkvdM 10:11, 13 October 2007 (UTC)

On Saturday (in fact, on the very day this question was posed - how curious!) I was at a convention where they had a "satellite link-up" with Stan Lee, and one of the people lined up to ask him a question actually offered to make him a set of Dr Octopus arms. Confusing Manifestation 22:35, 14 October 2007 (UTC)

Runaway Global Warming

What evidence is there for and against runaway global warming? Don't talk about related, but different, stuff such as the existence of global warming and the effects of humanity on it. Please state weather the evidence is about existentially dangerous or merely catastrophic runaway global warming, or both. Site sources if possible. — Daniel 03:12, 13 October 2007 (UTC)

We shall have proof of Runaway Global Warming after the fact and never before. 211.28.129.8 09:47, 13 October 2007 (UTC)

He asked for evidence, not proof. Alas, this sort of thing was not included in the IPCC report because of the low probability (or even inability to calculate a probability). Which is stupid, of course, because risk is a function of probability and seriousness. You're asking about both (good on you). I don't know about the probability, but I can give some considerations concerning the existential risk (the chances that mankind will become extinct, I understand). Such events have taken place many times in Earth's history, and the consequences have indeed been catastrophic. Even to the point that almost all life on Earth died. But with rapid change, it's the least adaptable species that die out. It just happens that mankind's strongest point is adaptability. I think no other (land) species is as widely spread across the globe, so we've already got experience with all sorts of climates. And if we encounter a climate that we're not familiar with, we'll learn. We do that like no other species. Basically, species adapt through evolution, so they need many generations. We can do the same thing within one generation. So mankind will almost certainly not die out. Maybe some 90% will die, but even then there will be 500 million left (more than is normal for a species our size, which is the cause of the problem, but that's a different issue, which you didn't want to hear about :) ). And it won't be any fun for the survivors, but their will to survive will ensure mankind will not die out. DirkvdM 10:31, 13 October 2007 (UTC)

The effects that might cause "runaway" global warming are the ones that have an element of positive feedback to them, there are three that I can immediately think of:

1. Increasing global temperatures cause the ice caps and glaciers to melt. Shrinking polar/glacial ice reduces the area of the earth's surface that is white and increases the area that is dark. This in turn reduces the earth's albedo - which causes more absorption of sunlight - and more global warming - and more ice melting. This effect could potentially runaway until there is no more surface ice year-round.
2. In a similar vein...as the climate warms up, the oceans get warmer. As water warms up, it expands (except at temperatures very close to freezing) - and that causes a rise in sea levels. This inundates some lighter coloured land areas with darker coloured sea water - which also causes the earths albedo to drop - increasing the absorption of sunlight and adding to global temperatures - causing the sea levels to rise still further.
3. In deep parts of the ocean, there are large deposits of frozen methane. If the ocean temperatures rise too high, these will start to melt. The resulting methane gas will bubble to the surface. Unfortunately, methane is an even more virulent greenhouse gas than CO₂ - so releasing more methane traps more sunlight which raises temperatures and in turn releases more methane.

You can argue about other effects such as the disruption of certain ocean currents - but these are more about affecting the weather in certain regions than they are about global warming - they aren't any less devastating - but they aren't likely to make global temperatures change much UNLESS they cause warm water to be carried to places where more ice or methane can melt.

The nasty thing about effects with positive feedback is that even if mankind mended it's ways overnight, if we've inadvertently triggered one of these feedback loops, we may not be able to prevent ultimate catastrophy (although we ought to be able to slow it down). The tricky part is to know at what global temperature each effect will kick in. The fact that the northern polar cap and the glaciers are all melting MUCH faster than we had formerly predicted means that we've almost certainly triggered that problem in the Northern hemisphere. Fortunately, the majority of the ice is at the South pole which doesn't seem to be in a runaway situation yet.

SteveBaker 11:32, 13 October 2007 (UTC)

Follow up question: I never heard about methane clathrate back in the dark ages when I was in school. Is it technically correct to talk in terms of natural sources of "frozen methane" on Earth? Methane says the melting point is -296.5 °F. --JWSchmidt 15:27, 13 October 2007 (UTC)

The stuff was only discovered 'in the wild' fairly recently. Technically, it's not "frozen methane" it's methane dissolved in water ice. However, when the water melts and turns back into liquid water it releases the methane as bubbles - so the effect is the same. This is fairly exotic stuff and it generally only forms at great depths - which explains why we only recently discovered these deposits. Our article suggests that there is a heck of a lot of this stuff out there - and it could even (theoretically) be mined as a source of fossil fuels (except that we're trying to use LESS fossil fuels - not more!) —Preceding unsigned comment added by SteveBaker (talk • contribs) 17:26, 13 October 2007 (UTC)

Steve, the southern polar cap is also shrinking in size - that is, at the sides, where the ice is on water, so there is the same feedback effect. This is in a way compensated by the fact that the ice gets thicker in the central parts, due to heavier snowfall, so the total amount of ice remains more or less the same. But that's not what counts here. In this case, surface size matters.

Concerning the slowing down of the first two effects (both albedo related), I suggested in a previous thread that we could scatter some reflective stuff like polystyrene on the oceans to replace the ice. That would reflect the light. An alternative would be to capture it with solar panels. These would not only prevent the seas from warming up, but would also provide us with energy, for which we would then not need to burn fossil fuels, so that would give a double positive effect. For the first effect, the panels would not need to be very efficient, so we can use the technology we have now. This would give a big boost to the solar panel industry, which would then have more of the money they lack so much now to develop more efficient and cheap solar panels. A very postiive feedback indeed, I dare say. :)

The third cause, the sudden release of methane, could be truly catastrophic. Methane is a greenhouse gas that is 62 times stronger than CO₂, but it has a shorter lifetime. I don't know what the most important of these two factors would be, but it is theorised to be have been a factor in the Permian-Triassic extinction event, which killed off almost all life on Earth. If this release were to take place in our lifetime, then it would not be mainly a problem for later generations. A sudden rise in temperature by several degrees (global average!) would likely cause massive crop failures the world over. Which of course would lead to war the world over. Not WWIII, because alliances will likely break down, but smaller continuous wars all over the world (a worldwide Darfur, so to say), which would probably be a whole lot worse. DirkvdM 08:14, 14 October 2007 (UTC)

The short lifetime of methane in the upper atmosphere is only partially comforting. When it breaks down you get CO2 and water vapour. Water vapour (at those altitudes) is another gas that's a stronger greenhouse gas than CO2. The amount of these methane clathrate deposits is estimated to be equal to the total amounts of underground natural gas deposits - so even after the stuff decomposes, it would be like putting 500 years worth of CO2 from fossil fuel usage into the upper atmosphere. SteveBaker 15:35, 14 October 2007 (UTC)

There are many positive and negative feedback loops. Theoretically, you could use them to construct an accurate model, but I very much doubt we know enough to make a very complete one, and thus any we make will probably only be accurate for a short time after it is made, if at all. By studying the Earth's history, it may be possible to find evidence for catastrophic runaway global warming. Specifically, how often have circumstances similar to what we are currently in led to it. Has anyone done so? Whether we can use our own planet as evidence against existentially risky runaway global warming is closely related to the Sleeping Beauty problem. Personally, I think we can. If so, a similar study to the one I mentioned for catastrophic runaway global warming can be done for it. Again, has anyone done so? By the way, DirkvdM, solar panels absorb much of the light that hits them as heat. This could be helped by making a coating that reflects light too low of a wavelength for the panels to use. AFAIK the painting the roof of houses in warm climates white saves more energy than solar panels make, and reflects more light into the atmosphere. — Daniel 21:49, 14 October 2007 (UTC)

Interesting idea. But how much ground do human settlements cover? Looking at the Netherlands on Google maps I'd say less than 10%. And the Netherlands is one of the most densely populated countries on Earth. If you zoom in about 2/3 of the way at a random location in the US, you need to search around quite a bit until you find any buildings. And even in densely populated India the buildings cover just a few percent of the ground. The total land surface on Earth is about 150 million km². So let's assume we're talking about 1 million km², where maybe 30% extra is reflected. Polar ice cap says "The area covered by sea ice ranges between 9 and 12 million km²". And the albedo difference between ice and water is more like 90%. So painting all (!) houses all over the planet white (yes, that includes your house plus all other buildings in your city) will have a compensating effect of just 1/30 of the melting of all sea ice, which is likely to happen much sooner than this paint job, given the slowness of politics (voters, really). Of course two more factors are that polar caps receive less sunlight and that roof tops cover less than half of a city's surface, which probably balance out against each other.

But any bit helps. There is no single all-encompassing solution, so we have to implement anything that might help. And this seems a very simple and cheap thing to do. So I'm all for it.

In what other ways can we change the albedo? Asphalt has an albedo of almost zero, and streets cover about as much ground as buildings in cities, so those could also be painted white. In cities they're not always in the sun, but in the tropics, the ones that run east-west are. But there are also the streets outside the cities. How much ground do they cover (literally)?

Btw, at first I thought you meant that if you cool a building with paint you need less airco. That'd largely be the southern US then because in most tropical countries most people can't afford airco, although shopping centres in most tropical countries do often have it. I think it would make more of a difference if they didn't turn it up so ridiculously high. What's the radiative forcing effect of cooling a 100,000 m² building down 5C, compared to the extra energy reflected by the same building if it got a fresh paint job? DirkvdM 07:59, 15 October 2007 (UTC)

That wasn't supposed to be a way to stop global warming. I'm more saying solar panels wouldn't do a very good job. 67.182.172.17 23:28, 16 October 2007 (UTC)

Where? Did you forget to log in? DirkvdM 06:09, 18 October 2007 (UTC)

Human birth defects???

Any and all text related to the subject of human birth defects. 1 Abnormalities related to but not limited to the following, herniated diaphram, herniated stomach. 2 Formentioned organ and conective tissue missplaced within torso cavity resulting in underdeveloped lung or heart tissue. All other information on human birth defects welcome. —Preceding unsigned comment added by Terrynisely (talk • contribs) 04:15, 13 October 2007 (UTC)

See situs inversus, teratology, diaphragmatic hernia, hypoplasia, hypoplastic left heart syndrome, congenital disorder, dextrocardia, congenital heart disease, congenital heart defect, and articles that they link to, for a start. - Nunh-huh 07:48, 13 October 2007 (UTC)

Category:Congenital heart disease has a bunch of them. Category:Congenital disorders has a lot more, and there is also List of congenital disorders. SteveBaker 11:14, 13 October 2007 (UTC)

Other things then what's been mentioned, e.g. Polydactyly. There are so many possibilities I'm not sure if you'd really want to study them all. It depends also on your definition of a Congenital disorder. For example I noticed Huntington's disease in one of the lists. While I'm not disagreeing, as far as I'm aware it's very rare or never that symptoms are present at birth even if the disorder is. Therefore should we also include any inherited genetic disorder (which would be present at birth)? But of course even this isn't a clear cut issue since there is no boundary between 'normal' and 'disorder'. Nil Einne 11:53, 13 October 2007 (UTC)

fixed point calculation by utilisation of non stressed axial expansion joints

i would like to know how the force is calculated on the anchor points in a vertical chill water risers used in high rise buildings. all the steps in detail. these risers have expansion joints to take on the expansion and how to calculate on to where these joints can be installed on the pipe. how much should the distance be between the expansion joint and the fixed anchow point at the top and bottom fixed points. —Preceding unsigned comment added by Mohdbilal123 (talk • contribs) 13:17, 13 October 2007 (UTC)

Well, from first principles, I guess you need to consider the hottest and coldest temperatures of the water in the pipe - look up the thermal expansion coefficient of whatever the pipe is made of - and from that calculate the total amount of expansion that has to be allowed for - then (adding a safety factor) divide that by the number of pipe segments you have. However, I would assume there were standards set for such things - and if such standards exist, those are what you should follow. SteveBaker 13:26, 13 October 2007 (UTC)

I'd guess that since there are expansion joints - you would want no force on the anchor points (common sense) - therefor you want to know how much expansion the expansion joints need - to get this you need the length between anchors, the thermal expansitivity of the pipe, and the expected temperature range. For safety include extra expansion in the expansion joints for extreme conditions etc.

You can work this out in reverse as well - for a expansion joint that can expand x - calculate how much pipe it can allow to expand under given temperature ranges - so for a total pipe length you can work out how many expansion joints you need.. (Was this relevent?)83.100.254.51 13:33, 13 October 2007 (UTC)

gdfghdrg

tr RTAWT —Preceding unsigned comment added by Mohdbilal123 (talk • contribs) 13:37, 13 October 2007 (UTC)

Pardon me? —Keenan Pepper 13:58, 13 October 2007 (UTC)

You are hereby pardoned. DirkvdM 10:06, 14 October 2007 (UTC)

AYYLU. --JWSchmidt 14:50, 13 October 2007 (UTC)

¡Atención! ¡Atención!. Markovian Parallax Denigrate. Resurrect dead on Planet Jupiter. 12 Galaxies Guiltied to Omegalogical Exortations. GeeJo ^(t)⁄_(c) • 00:25, 14 October 2007 (UTC)

Google search on gdfghdrg and tr RTAWT neither of which seem promising. I suggest trying the wikipedia sandbox instead. 71.226.56.79 22:18, 14 October 2007 (UTC)

Oh great, another genius. And how many of those do we have here? *rolls eyes* But anyway, have you tried combining the two terms into one google search? NASCAR Fan24^{(radio me!)} 22:21, 14 October 2007 (UTC)

The only non-nonsensical google hit I get is thus: (Saporin and ricin A chain follow different intracellular routes to enter the cytosol of intoxicated cells). Though I think the more likely answer is that Mohdbilal123 was using a public computer to ask the above question and forgot to log out, leaving the door open for some random person to come along and type in gibberish. --VectorPotential^Talk 12:45, 15 October 2007 (UTC)

Raising metabolism

In theory, how high could the metabolic rate in humans be raised as a percentage of the average human metabolic rate?

My interest in this comes from an article I read about the powers of characters in the TV show Heroes. One character has rapid spontaneous regeneration ability and the article I read said that she would need an incrediably high metabolism to achive this. I'm aware that the ability to heal this quickly would be physically impossible (it would require constant eating and cardiovascular exercise, leading to indigestion) but I'm curious about how fast human metabolism could be raised.

-- _{Escape Artist Swyer} ^{Talk to me} _{Articles touched by my noodly appendage} 14:41, 13 October 2007 (UTC)

One problem with any significant amount of increase would be that metabolism produces heat. Increasing heat production would push up your body temperature - and taken to superhero extremes that would not be a healthy thing. This probably explains the skimpy costumes that those guys wear! :-) (Although, not in Heroes).

Oxygen is a rate limiting factor for human energy throughput. There are some numbers at VO2 max suggesting that it is rare for the best athletes to be able to sustain more than 3 times the oxygen uptake of the average person. I guess "in theory" might include genetically engineered humans. According to this dogs can do 3 times better than the best humans, so it might be possible to modify humans genetically and increase the maximum aerobic capacity. --JWSchmidt 15:14, 13 October 2007 (UTC)

And to back up my earlier point, dogs have a significantly higher body temperature than humans. There is also (across all mammals) a strong correlation between lifespan and body temperature - so increasing your metabolic rate will also (on the average) result in you dying sooner. SteveBaker 17:15, 13 October 2007 (UTC)

I've been thinking about healing and cell division and even noticed that Wikipedia has "healing factor". I've never seen Heroes, but I've had a chance to consult with my kids and they claim that on that show a character was shown regenerating a toe in a few seconds. For a relatively small amount of tissue repair/regeneration such as this, I do not think that "metabolic rate" is really the issue. There are limits on how quickly individual cells can reproduce and organize themselves. To get around these physical limitations, I think rapid regeneration would require special stores of cells and some kind of special cell migration process. After injury, pre-formed bone, muscle and other cell types would have to be quickly released from storage sites and transported (in the blood?) to the wound where they would have to efficiently assemble into tissues. There is no known mechanism for such assembly of differentiated cells into complex organs and limbs. As described at regeneration, animals that can regenerate structures form stem cell masses that must slowly differentiate and organize into new tissues using the kinds of cell-cell interactions used during normal embryogenesis. So I think you would have to say that some kind of shapeshifting is required, maybe involving some kind of nanorobotics (functional and structural components that are not conventional cells). I'm not an engineer, but it seems to me that if you can imagine some type of sophisticated self-organizing nanobots that can quickly shape themselves into a toe, then I do not see why we would have to assume that such self-assembly would require large amounts of energy....someone with the ability to design such nanobots would probably be able to make their assembly efficient. If you get into needing to rapidly produce (from conventional organic molecular building blocks?) a large mass of such nanobots in a short period of time using conventional metabolic energy sources, then in addition to energy concerns for synthesizing the nanobots, you might have a problem related to limitations on the rate at which storage molecules like glycogen and protein can be broken down and their molecular components released from cells. I end up thinking that it is unrealistic to imagine that "metabolic rate" is the only limiting factor. --JWSchmidt 18:39, 13 October 2007 (UTC)

I can't quantify how much metabolic rates could be increased as I'm not an expert in biochemistry. What I do know from my limited knowledge in biochemistry is that many (if not most) enzymes that we have operate close to the maximum rate that nature allows. A way to increase the rate in metabolism is to have all metabolic enzymes run at their most optimal rate. Another way to raise metabolic rates is to have more efficient pathways. Metabolic pathways are very complex; for a particular biological function, some organisms have more efficient pathways in completing that function. (For example, instead of requiring two steps and enzymes to synthesize a product, only one is needed. There are many sorts of evidence of this in nature. Evolutionary mechanisms have forced certain species to develop better pathways.) And as the questioner mentioned, quick regeneration is impossible without constant eating. With the two things I mentioned about increasing metabolic rates, none of them would matter if there is no increased intake of molecules that contain consumable energy.128.163.113.152 17:50, 16 October 2007 (UTC)

What is the chemical composition of a typical computer?

Hey. I understand that my question might look pretty weird, but what I want to know is what elements a typical computer would be made out of- specifically, would it contain a majority of organic compounds, or inorganic ones? Any help would be appreciated. Thanks in advance! 68.54.42.126

First, make sure you know the difference between element and compound. Here is a guess at the most common elements a computer is made of: carbon, oxygen, hydrogen, chlorine, aluminum, iron, copper, silicon.

Plenty of other trace ones after these.

Because of the housing, circuit board, and wire insulation, I bet organic compounds would be most prevalent Delmlsfan 17:21, 13 October 2007 (UTC)

Iron (steel) for the case and transformer, a lesser but similar amount of copper for the wires.

There's some silicon in the chips but also in the glass fibre in the printed circuit board.

Very Small amounts of other elements in the chips eg germanium etc (tiny).

Relatively small amounts of other metals - gold/silver/tantalum etc in wires/contacts/capacitors

The remainder will be 'plastic' - almost certainly hydrocarbons eg polystyrene, ABS, polypropylene etc - a quite large perentage of the mass of the plastic will be filler - this can be chalk, gypsum, silica, feldspar, titania (any inert mineral) or even carbon fibres or other exotic materials.83.100.254.51 17:20, 13 October 2007 (UTC)

If PVC is used in plastic shielding of cables this means that chlorine will also be present, anything made of teflon (not unknown in cableing and insulation) would introduce fluorine

And the heat sinks are likely to be made of aluminium

Any paint will be carbon based - though the pigment might contain other elements

By mass I'd expect iron to be the major component - next copper, then carbon as plastics, then silicon and oxygen (not sure which is most) plus a similar amount of aluminium if you have large heat sinks (may also be present in filler), followed by hydrogen (in the plastic) and then all the trace elements (gold, boron etc)83.100.254.51 17:27, 13 October 2007 (UTC)

According to a number of computer recycling websites, there are about 5 pounds of heavy metals like cadmium, arsenic, and mercury in the computer motherboard and CRT monitor. --24.147.86.187 17:28, 13 October 2007 (UTC)

That sounds wrong - were would these elements be found?83.100.254.51 18:23, 13 October 2007 (UTC)

If you're including the CRT then you have a lot of glass (Silicon, Oxygen) and Phosphorous in the face-plate - plus a bunch more copper, etc from the circuitry and plastic in the case. I'm not qualified to guess what an LCD panel includes - certainly more plastics, copper and glass - but what is the liquid crystal made from? A plasma display presumably has some of the novel gasses in it...dunno, my knowledge just ran out! SteveBaker 17:37, 13 October 2007 (UTC)

The plasma gases are xenon or krypton according to plasma display

The phosphors are not phosphorus - they are rare earth oxides typically, or Zinc sulphide or... see the article for more details

Liquid crystals are organic compounds - C,O,H are certainties here.83.100.254.51 18:21, 13 October 2007 (UTC)

The greatest use of Indium is in thin films including flat-panel displays. Cheers Geologyguy 18:16, 13 October 2007 (UTC)

Don't forget laptop batteries - typically add lithium and cobalt to the elements83.100.254.51 18:22, 13 October 2007 (UTC)

Electronic waste might be useful.

Forgot to mention all that lead and tin in the solder - quite a lot of this...83.100.254.51 18:28, 13 October 2007 (UTC)

Plus a disk drive or cd rom (as well as hard disk) will most likely have a cast metal base - these are made out of aluminium/zinc/(possibly magnesium) alloys.83.100.254.51 18:43, 13 October 2007 (UTC)

Wow, there are quite a few responses! Thanks for the help! 68.54.42.126 —Preceding signed but undated comment was added at 20:07, 13 October 2007 (UTC)

All those elements just to download porn. Delmlsfan 21:59, 13 October 2007 (UTC)

For older (pre 2005) computers, there is a fair amount of lead in the solder. Newer computers comply with ROHS and do not have lead in the solder. Quite a bit of tin either way. For CRTs, there is a fair amount of lead in the glass. -Arch dude 00:27, 14 October 2007 (UTC)

That's an EU law, not a worldwide one, however. Rmhermen 13:44, 15 October 2007 (UTC)

True, but since the computer market is a worldwide one, it's usually cheaper to make computer parts RoHS-compliant than it is to make different products for the EU and the rest of the world. --Carnildo 21:39, 15 October 2007 (UTC)

infrared

What is the reason that (absorption of?) wavelengths surrounding 3μm causes the temperature of atoms and molecules to rise? In particular, can you tell me if it is due to a correspondence between wavelength and the dimensions of an atom or molecule? Clem 16:50, 13 October 2007 (UTC)

Absorption of light of any wavelength causes the temperature to rise - it's just energy. Perhaps your question should be "Why do materials absorb more light in the 10,000nm band than elsewhere in the electromagnetic spectrum?" (I'm not sure that's true either - but it's a better question!) SteveBaker 17:03, 13 October 2007 (UTC)

Infrared spectroscopy may be of some use here, though it is of some middling quality. Essentially, molecules (not atoms!) have specific vibrational and rotational frequencies, some of which just happen to match the IR band. These "resonant frequencies" explain why the molecules absorb EM radiation of those particular wavelengths. As the energy of the molecules is increased by doing this, the average energy of the system (temperature) increases. Note though that there are many vibrational frequencies outside of the IR range (which is why UV-vis spectroscopy works). GeeJo ^(t)⁄_(c) • 17:11, 13 October 2007 (UTC)

Is there a graph of resonant frequencies showing various molecules which might reveal how they are grouped or more closely distributed around 10,000nm? And for that matter a graph showing temperature rise on a black body surface for different wavelengths of radiation at the same intensity? Clem 21:25, 13 October 2007 (UTC)

For the first question, I'm not sure anyone's really looked that deeply into absorptions around that region for the simple reason that everything in the lab is going to be emitting radiation in that band, making it impossible to get any decent resolution. For the second question, a black body absorbs all radiation by definition, so it'd be a fairly dull graph, with E=hv determining the change in energy contribution from the various wavelengths. GeeJo ^(t)⁄_(c) • 22:41, 13 October 2007 (UTC)

In general any absorbsion of any light wavelength will cause an increase in temperature - the more light - the more the temp rises - 10,000nm isn't particularily special here. —Preceding unsigned comment added by 83.100.254.51 (talk) 17:13, 13 October 2007 (UTC)

That contradicts visible light having a higher energy level than IR yet not producing the same rise in temperature as IR of the same intensity. Clem 21:28, 13 October 2007 (UTC)

You seem to be under the misapprehension that IR wavelengths are somehow "more heating" than those of visible light. If you pointed lasers with beams in the visible and IR bands at a black body, I guarantee you that the visible will heat it more quickly. GeeJo ^(t)⁄_(c) • 22:55, 13 October 2007 (UTC)

ee assay

Does anyone know what an ee assay is? It is simply any assay used to determine the mixture of enantiomers, or is it something more subtle or completely different?

Thanks,

Aaadddaaammm 22:19, 13 October 2007 (UTC)

Enantiomeric excess mentions some specific methods for assay of "ee". --JWSchmidt 16:00, 14 October 2007 (UTC)

Thank you very much! I don't know how I missed that when I searched. Cheers! Aaadddaaammm 22:22, 14 October 2007 (UTC)

becoming an alcoholic without alcohol.

How might someone become an alcoholic, if you don't include alcohol or anything that breaks down or combines etc into alcohol. Can you substitute alcohol with something else (non-alcohol) and cause someone to become alcoholic over extended, high-volume ingestion? (This is just one example, another source of alcoholism, such as a pill that affects neural structure or something jsut taken once, would also fit my request). Thank you! —Preceding unsigned comment added by 81.182.100.153 (talk) 22:21, 13 October 2007 (UTC)

Some research on alcoholism has suggested that there could be specific neurotransmitters involved in alcohol addiction. For example, endorphin activity might be enhanced by ethanol, allowing a receptor antagonist such as naltrexone to possibly inhibit addiction to alcohol (See). Hypothetically, there might be some drug that could be chronically administered which would cause a person to become addicted to that drug and would at the same time predispose the person to alcohol addiction. If you are creating a plot element for a science fiction story, it might be more trendy to invent a polynucleotide analog or a viral vector that would genetically predispose someone to alcoholism. See also: Wikipediholic. --JWSchmidt 15:40, 14 October 2007 (UTC)

Some people lack the genes to make enzymes needed to break down alcohol. This makes them predisposed to NOT be alcoholics, I suppose. This is documented in Alcohol flush reaction. Personally, I don't believe that alcoholism is a strictly phisiological condition, though. I'm not sure if what you're asking is possible. --Mdwyer 15:54, 14 October 2007 (UTC)

You'd have to convince them that whatever they're drinking is alcoholic. If they know it isn't, they'll have no way of knowing alcohol will satisfy their craving, and thus they couldn't be considered alcoholic. — Daniel 21:53, 14 October 2007 (UTC)

Resonant frequencies

Where might one find a list of resonant frequencies for various molecules? Clem 22:35, 13 October 2007 (UTC)

Any good spectroscopy textbook will carry table upon table of the things. The only one I can find on Wikipedia itself is for a few organic bonds in the near-IR range at Infrared spectroscopy correlation table. GeeJo ^(t)⁄_(c) • 23:04, 13 October 2007 (UTC)

There must also then be a graph showing the distribution of molecules across these and other wavelengths such as Different regions in the infrared. Do you know of any others aside from Summary of absorptions of bonds in organic molecules? Clem 23:14, 13 October 2007 (UTC)

There are more detailed versions of the graph you mention out there - were you thinking of organic molecules specifically or anything? - a search for "IR absorbtion bands table" or "ir functional group" turns up thousands (try image search)

For example here is one for nitrogen functional groups http://www.vidrine.com/vcorr3.htm

And here is a paper containing a spectra for silicates (scroll down) http://www.aanda.org/index.php?option=article&access=standard&Itemid=129&url=/articles/aa/full/2002/31/aah3549/aah3549.right.html

There probably are millions - if you need more help please ask.87.102.19.106 04:39, 14 October 2007 (UTC)

Yes, this seems to be what I'm looking for, one question though, are absorption frequency and resonant frequency the same or do they refer to different phenomenon, and if not, are there graphs for resonant frequency? Clem 14:01, 14 October 2007 (UTC)

Yes - in terms of IR the absorbtions cause physical vibrations of the molecules at the resonance frequency of the bond - so the absorbance frequency is the same as the natural resonance frequency of a bond. they have the same origin/meaning/frequency87.102.82.26 17:54, 14 October 2007 (UTC)

OK, then things now add up. A microwave oven works because it operates at whatever the absorbency/resonance frequency of food is so the food heats up. What I'm locking for then is an online graph that extends all the way from zero to the highest frequency known that shows the frequencies at which something (everything from atoms to kettle drum) resonates. Clem 18:30, 14 October 2007 (UTC)

Yes, that's right - though typically the microwave oven is 'tuned' to water's frequency - or OH (hydroxyl) groups - microwave ovens don't heat up fat as well as water for this reason (though they melt butter well because butter has water in)

No, 2.5GHz microwave ovens aren't tuned to water resonance which is up above 10GHz. Also, while water gas (vapor) does have sharp resonance frequencies, liquid water does not. If a microwave oven was actually tuned to a sharp frequency for water, then the food would be opaque to the radiation, and only a tiny outer layer of the food would be heated. Because the oven's operating frequency is far from any absorption peak, the RF energy passes deep into the food before being absorbed. --128.95.172.173 01:24, 16 October 2007 (UTC)

second question - I've never seen but would like to see too such a graph.. Can't find one.87.102.82.26 20:44, 14 October 2007 (UTC)

reduction of multiple state logical equations

If “… we're overrun by really efficient algorithms. “ (SteveBaker 13:40, 8 October 2007 (UTC)) to reduce logical equations to minimum form, which of these algorithms is capable of reducing multiple state equations to minimum form? Clem 22:53, 13 October 2007 (UTC)