Wikipedia:Reference desk/Archives/Science/2007 June 26

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June 26

Harvesting Static Electricity

Can static charges be deliberately accumulated and then discharged into a storage device? E.G. If bundles of fibreglass fronds are placed in an open air test bed and allowed to collect a charge, could it be then periodically discharged in useful ways?

Is there an experiment in the existing body of knowledge that deals with this? 203.21.40.253 03:35, 26 June 2007 (UTC)

See Leyden jar.—eric 03:44, 26 June 2007 (UTC)

Static electricity comes in unpredictable amounts, making it probably financially unrealistic to try and harvest it and put it to practical use as we can solar energy. Some of the older books on electricity have sections on using static electricity to cause mechanical motion. An example is "Elements of Static Electricity with Full Description of the Holtz and Töpler Machines..." by Philip Atkinson , 1887, which can be viewed free at Google Books [1]. On pages 102-107 it describes how to have a set of 3 chimes operate from static electricity, how to generate a breeze, and how to make a rotor spin. The book also describes Leyden jars (CAUTION! Static electricity stored in a Leyden jar or any capacitor can cause painful or fatal shocks! Do not experiment with it!). Edison 15:27, 26 June 2007 (UTC)

Thanks to EricR and Edison!203.21.40.253 11:29, 28 June 2007 (UTC)

Land/Water ratio for Northern Hemisphere

It's well known that about 70% of the Earth's surface area is covered with water. How does that break down by hemisphere? Most of the land is in the Northern Hemisphere. What percent of the northern hemisphere is water? -GTBacchus^(talk) 04:54, 26 June 2007 (UTC)

61% in the Northern and 81% in the Southern [2] — Lomn 13:03, 26 June 2007 (UTC)

It's interesting to look at the diagram in our Antipodes article. There is amazingly little overlap between land on one side of the planet and that on the opposite side. SteveBaker 03:56, 27 June 2007 (UTC)

Thank you both! -GTBacchus^(talk) 19:22, 27 June 2007 (UTC)

Notch Signalling - Why capital 'n'?

When talking about Notch signalling, it appears to be standard practise to capitalise the 'n' in Notch but I don't understand why, since it's not a propernoun. Why should I capitalise the 'n' in Notch? --Seans Potato Business 05:38, 26 June 2007 (UTC)

Notch is capitalized in scientific literature because it is a particular family of proteins and genes, and I believe that the style rules for journals always capitalizes those names, like you'd see for trademarks or brand names in other literature. Other examples: Hox genes. -- JSBillings 12:18, 26 June 2007 (UTC)

I'd disagree with above. In Drosophila, a captilized first letter for a classical gene is due to the fact that the first allele was dominant. David D. (Talk) 07:34, 27 June 2007 (UTC)

David D makes a valid point. It used to be, when classical alleles were named from their mutant phenotypes, that a leading cap indicated the allele was dominant and no leading cap meant the allele was recessive (e.g. the mouse agouti allele resulted in a black mouse, while the Agouti allele resulted in a brown mouse). However, more recently in the post-genomic age, fewer genes are named for alleles or phenotypes, instead the gene sequence is named. For reasons better known to the diverse scientific communities and the stubborn people within, gene symbols from different species have different nomenclature rules. Last I heard (and they sometimes change) mouse, rat, Drosophila and most other species' genes have a leading cap (Mc1r), plant and human genes are all caps (MC1R), zebrafish genes have no caps (mc1r). The default tends to be the leading cap. I should add this is the nomenclature for the gene symbols (the abbreviations) the full names all tend to have different rules. Notch is an old skool allele named for the wing phenotype of a mutant, but like many of the old skool names, it is now used to describe the gene itself, and the cap no longer generally used in a manner that indicates dominance. See the following links for the rules for humans, flies and mice. Rockpocket 08:20, 27 June 2007 (UTC)

Cowper's Glands

I am weak and my Cowper's Glands release much Precum when I love with my wife and I become weaker. I was affected with Hepatitis C few years ago but now its ok. Please any doctor tell me if I remove my Cowper's Glands, what it will effect on my health or fertality or erection etc? Thanks —Preceding unsigned comment added by 203.135.56.10 (talk • contribs) 06:57, 26 June 2007

As stated at the top of this page, Wikipedia cannot, indeed must not, give you medical advice. See your doctor. Do not attempt to remove your Cowper's gland! Try a love position that is more relaxing for you.--Mrs Wibble-Wobble 08:11, 26 June 2007 (UTC)

As your question suggests that you already know, the cowper's glands secrete pre-ejaculate. The purpose of this fluid is (among other things, undoubtedly) to lubricate the urethra and create a favorable environment for healthy sperm to travel down the urethra and into the vagina. (There appear to be many factors which collectively create this favorable environment: pH, lubrication, inactive spermatids, binders etc.). Therefore it follows logically that removal of the cowper's glands would result in decreased fertility. The Biblical, Chi Kung, Hindu, and Buddhist notions that semen and its storage is related to energy is nonsense. The production of sperm is a natural and continuous process in all healthy adult males. Sperm is not stored in any long-term sense, and is reabsorbed after a short period. The energy used to create semen is not significant in the lifestyle of a healthy man. Bluntly, there is no reason to suspect that by creating more semen, under normal circumstances, one is draining one's energy. However there are pathologies related to excess seminal fluid production, and if you suspect that there is anything abnormal about your sexual function or energy reserves, you should consult a physician. Tuckerekcut 14:55, 26 June 2007 (UTC)

Well thats the first I heard about the Biblical notion of semen and its storage being related to energy. — Shinhan < talk > 21:21, 30 June 2007 (UTC)

Speed of turbulent incompressible flow

I am trying to develop a model of fluid flow through a pipe, and am using Coulson and Richardson, Chemical Engineering vol. 1. This has a nice discussion of predicting the total flow rate through a circular pipe for a turbulent Newtonian liquid, and gives an approximate equation: volume flow rate = 49 * pi * radius^2 * (maximum speed) / 60. However, I have been unable to find information about predicting the maximum / central speed of flow through the pipe, is it possible to calculate this theoretically? 84.12.252.210 08:11, 26 June 2007 (UTC)

For a fully developed turbulent flow, the empirical relationship
${\bar {u}}/V_{c}=(1-r/R)^{1/n}$
(from [3]) should give you an approximate result. n is a function of Reynolds number, and should be between 6 and 10. Keep in mind this is empirical, rather than theoretical. - anonymous6494 22:34, 26 June 2007 (UTC)

Thanks a lot, this is seriously helpful. The equation you gave is in the book I am using, however it assumes from the start that n=7 with no explanation (I think my 49/60 should have been $2n^{2}/((n+1)(2n+1))$. I think I may be being incredibly stupid, but this equation still doesn't allow me to calculate the actual speed through the centre of the pipe, it just gives the relative distribution of speeds, doesn't it? Does the speed through the centre need to be known empirically? I really need to get hold of the book you mentioned... 84.12.252.210 08:20, 27 June 2007 (UTC)

I don't have the book in front of me, but I believe you're looking for $V_{c}$, and at the center of the pipe $r=0$. $R$ is the radius of the pipe, and ${\bar {u}}$, the mean flow velocity, is trivial to compute given the flow rate and pipe dimensions. -anonymous6494 14:46, 27 June 2007 (UTC)

I apologise for being repeatedly awkward, but I only know the flow rate through the pipe by integrating your equation across the cross section of the pipe, so I only know the flow rate in terms of the speed at the centre of the pipe... wait, I'm confused. By the mean flow velocity, do you mean the average over the cross section of the pipe, or the average over time at a distance r from the centre of the pipe? If it is the first, your equation doesn't seem to make sense, if it is the second then I don't see how it can be trivially calculated except in terms of $V_{c}$. My head is starting to hurt, I think I need a trip to the library to find a decent fluid mechanics textbook. Yes, I will (go to a library), I've decided I need to look up lots of other stuff now. Please don't go out of your way to reply again, even if you can make any sense of my train of thought. :) Thanks for your help! 84.12.252.210 15:22, 27 June 2007 (UTC)

Boeing 747 Vs Airbus 340

How are they different between Boeing 747 and Airbus 340 [also A330 & A300]? And I'd like to know what better one is in your opinion.

Acually, I have already searched them in This website, but i don't know exactly how to contrast them. So, i need your good experienced suggestion and i'll take the suggestions to do Airline report to present my teacher.

I would appreciate if you could answer my question

Many Thanks... —Preceding unsigned comment added by 61.47.26.1 (talk • contribs)

To contrast the aircraft you can compare them along any number of dimensions - size, capacity, engine power, speed, range, cost, number sold etc. etc. Our articles, which you have already seen, should provide all the raw data that you might need. As far as which aircraft is the best, then your teacher doesn't want our opinions - he wants to know your opinion (maybe with some arguments that back it up). So we can't help you with that one. Gandalf61 10:40, 26 June 2007 (UTC)

This has been asked twice in the last week: [4] [5] - 213.48.15.234 10:53, 26 June 2007 (UTC)

Yellow tabs on heavy vehicle nuts

I've noticed that the wheel nuts on some large vehicles (particularly large trucks) are augmented by a teardrop shaped plastic object (which is often yellow). It's not clear to me whether these are some kind of washer (in which case I don't understand the purpose of the triangular part that sticks out) or whether they're just clipped around the already fitted wheel nut (in which case I really can't see any purpose for them). They're not always present (some wheels have some with them, and some without), and their angle doesn't appear to have any pattern to it. I'm sure they're not just for decoration. I've looked in the likely Wikipedia articles (nut, bolt, bolted joint, wheel nut, lug nut), and I don't see any mention. It's not a nyloc nut, although if the plastic thing really is in the joint like a washer, perhaps it's part of a similar locking mechanism. I've failed to google anything worthwhile about it (and I can't find a clear photo of on on Google Images). Does anyone know what these things are? -- Synthetic element 14:29, 26 June 2007 (UTC)

Sometimes I've seen these all pointing toward the wheel center, I've also seen them point erratically as you describe. I don't know if theyre supposed to point to the center, or if it's just aesthetic. I'd love to know what they are too. 213.48.15.234 14:38, 26 June 2007 (UTC)

AFAIK, they're just indicators, fitted to the nuts after tightening. When the nuts are torqued up, the tabs are fitted over in pairs with the tips facing each other. Since loosening the nuts would cause the tips to move in opposite directions, it's obvious at a glance if one or other of the nuts has worked loose. If they're pointing at "erratic" directions, that suggests that whoever's responsible for checking them isn't doing a very good job! This is all speculation on my part but it seems the most likely purpose for them. --YFB ¿ 14:47, 26 June 2007 (UTC)

Tada! Thought so. --YFB ¿ 14:50, 26 June 2007 (UTC)

Well done, thanks. Like 213.48.15.234 I think I've seen too many that point at jaunty angles, so maybe the wheels quite literally are about to come off the European transport industry. Ideally Wikipedia would have an article about these - the generic term seems to be loose wheel nut indicator. -- Synthetic element 14:57, 26 June 2007 (UTC)

Here's what the Europeans have in store: [6]. DMacks 17:47, 26 June 2007 (UTC)

Hmmm - these yellow gizmo's wouldn't have helped there - the problem with the busses was that the nuts had been over-tightened and snapped the bolts off. The things we're talking about here are to help indicate when a nut has worked loose...quite a different problem. Havn't those guys ever heard of a torque wrench?! SteveBaker 03:52, 27 June 2007 (UTC)

Cat bite

I have been biten by my beloved cat while I was doing what he probably considers hard core water torture. Anyway the bite has swelled a bit and I was wondering what signs should give me the warning to stop entertaining myself while my body heals it's self and look out for one of the men in white? Bastard Soap 16:03, 26 June 2007 (UTC)

medical advice removed

Please see a professional if you're looking for medical advice. We're not qualified or competent to give medical exams over the internet. (Visit a local walk-in clinic, see your family physician, call your local 'telehealth' phone number, or speak to your local pharmacist/chemist.) TenOfAllTrades(talk) 17:20, 26 June 2007 (UTC)

Yeah, do so. But make sure ask the person on the line if they are a Wikipedian, because then they are apparently not competent! —Bromskloss 18:01, 26 June 2007 (UTC)

If someone who is allergic to an animal is bitten by that animal, a prominent wheal (weal) will commonly develop. This is the same mechanism of reaction as an allergist provokes when doing a skin test to identify possible allergies. Please note that this comment is an explanation, and offers no advice whatsoever on treating cat bites.

Atlant 19:40, 26 June 2007 (UTC)

A danger signal of infection needing immediate medical care is red streaking from the point of the wound, visible through the skin. Gzuckier 20:13, 26 June 2007 (UTC)

Same goes for this comment (not medical advice) - cat bites, especially of the hand, have a high rate of infection. One of the signs of infection is swelling. See PMID 7625323 and see a doctor. --Joelmills 20:12, 26 June 2007 (UTC)

Beware of Cat Scratch Fever. —Steve Summit (talk) 23:21, 26 June 2007 (UTC)

cat bites on the hand are notoriously dangerous, because [1] cats have normal flora in their mouths that cause severe infection in humans (e.g., unusual organisms such as the NO-1, Actinomyces, Porphyromonas & Pasteurella sp., or more common ones like Staph), and [2] because the hand is a "closed space" within which such infections, especially anaerobic ones, easily spread. If unchecked the infections may require surgery for drainage. Most physicians would prescribe antibiotics early rather than wait for complications. It would be a very good idea for you to visit your doctor to provide them with that opportunity. The swelling you already have is a sign that you should do so. - Nunh-huh 00:06, 27 June 2007 (UTC)

Dark energy and wormholes?

Dark energy produces a negative pressure. Does this mean that it can be used as the exotic matter to stabilize wormholes? --Zemyla^t 16:09, 26 June 2007 (UTC)

As far as I understand, "Dark energy" is just a convenient term for the cosmological constant, which can be expressed in units of mass or energy per unit volume, but inherently pervades space in a uniform manner. Clearly, all of this is subject to revision as new theories emerge, but I am not aware of any current theories which would allow a local concentration of dark energy for any purpose. (By the way, wormholes are purely theoretical, something allowed by the mathematics of general relativity but never observed. It is possible that the theory does not apply at the scales necessary, and it is also possible that they are stable but nonexistent, ie, that there is no way to create them.) --Homunq 20:22, 26 June 2007 (UTC)

Well, very little is known about dark energy. It's true that if w = -1, then dark energy acts like a cosmological constant, but people don't necessarily assume this, WMAP3 gives w = -1.02 ± 0.02, if I recall correctly. Dark energy might just be some substance with P = -E, or pressure equal to negative the energy density. The short answer is - nobody knows that. WilyD 20:27, 26 June 2007 (UTC)

Quintessence is the theory of "corpuscular" dark energy that would allow it to be arranged and concentrated. A cosmological constant is preferred theoretically, but both possibilities are consistent with observations. Whether quintessence is useful for wormholes, I have no idea. Dragons flight 20:27, 26 June 2007 (UTC)

omega 3 or omega minus 3?

Chemists and biochemists: is this true? Actually, they are "Omega minus 3" fatty acids. The term omega-3 (aka "n-3", "ω-3") signifies that the first double bond exists as the third carbon-carbon bond from the terminal methyl end (ω) of the carbon chain. [7], which I interpret as meaning that you are actually counting up three from the "bottom" of the chain. The folks editing the Omega_3 article would like to know. Thanks. Gzuckier 16:11, 26 June 2007 (UTC)

Right! But why you ask for an artikle from answers.yahoo.com and not the original much better wikipedia article? The saying: "from alpha to omega" meaning from beginning to end states clearly that omega is a synonyme for the end of the chain. Better use the delta or the normal en nomenclature for these kind of substances, because this naming convention is not used by chemists anymore. It contradicts the counting rules of IUPAC. The food and nutrition manufacturers use this naming convention because it sound good.--17:13, 26 June 2007 (UTC)

(edit conflict) Apparently it is[8], according to the University of Utah, although it's a moot point, as "Omega plus three" would not be possible (you would have to count down from the bottom!). I suppose if you wanted to count from the start, you could use the alpha point, but there would probably be no need, given the wide use of the omega system. Laïka 17:22, 26 June 2007 (UTC)

Electrical resistance of the earth

What is the resistance of the earth? If I stick two metal probes in the ground and apply a DC voltage between them what level of current would flow? Would the current decrease if I put the probes further apart? What if I put the probes thousands of miles apart, would a current still be discernible for practical voltages ( e.g. <1000V ) ? Even if there was nothing but miles of rock and dry desert in between?

Do all the possible parallel routes between the probes need to be considered? For example, in the extreme case, current traveling away from the other probe and going right round the world before reaching the other probe from the other direction. Is there a path straight down through the center of the earth?

The reason I ask is that I have been reading about early telegraph cables that used the earth to complete the electric circuit between transmitter and receiver, and wondering how this is possible. My intuition would be that the resistance of 1000s of miles of desert would make such a system impractical. The article on earth (electricity) seems to suggest this, but I thought telegraph communications were routinely possible back then, despite what the article says.

And what about earth connections used for wireless transmission? E.g. If I build a simple radio transmitter and a radio receiver, such as a crystal set, I believe they will both need earth connections. Is this to provide a common reference voltage between them? That is, are both sets' earth connections are at the same potential? How does this work across dry ground? Should I drive the earth connector so deep that it meets the water table, where the ground will be much more conductive? TIA Alf Boggis 16:46, 26 June 2007 (UTC)

I can answer only a few little bits. Probes further apart will make the current smaller, yes. All possible paths need to be considered, as I imagine the current will spread out as it leaves the source and collect toward the target. You do not need a common ground for radio transmission. Your mobile phone obviously isn't connected to the ground, for example. —Bromskloss 17:48, 26 June 2007 (UTC)

Thanks for your reply. I wonder why earlier radios (lower frequency) required earth connections. Alf Boggis 19:13, 26 June 2007 (UTC)

Radio antennas need two elements that are energized with an electrically-opposite polarity. For very small radiowaves, these two elements can be concealed within the same physical antenna. For larger radio waves, a "ground reference"/ground plane commonly acts like a sort of "mirror" to provide the other electrical pole of the antenna. In the case of cell phones, you are commonly the ground reference (because you are much bigger than the radio wave). For old-fashioned AM/medium wave transmitting towers, a large array of copper cables is buried out in the ground in a radial fashion extending from the antenna. Moist ground makes this a lot easier; it's no accident that the New Jersey Meadowlands are full of AM broadcasting stations as the swampy ground there makes it very easy to set up an effective ground plane. See also dipole antenna, monopole antenna, whip antenna, and image antenna.

Atlant 19:49, 26 June 2007 (UTC)

It's absolutely not true to assume that two earth connections at geographically distinct places will provide a reference ground - as Ground loop (electricity) notes "electrical potential at different points on the surface of the Earth can vary by thousands of volts". Note also that not only can signal be transmitted with an earth return, even power can - see Single wire earth return and Single-wire transmission line. Now it's my understanding that this all works because the Earth can be looked at as an infinite repository of both positive and negative charge. So if there is a wire between us, we can both measure the potential between it and the earth (it won't be the same, but so long as it doesn't change we don't care). If I then wobble my potential a bit (by briefly attaching my voltatic stack) you should see a wobble too. You're really correct, there really is a returning ground path, and it does (in a theoretic way) follow a big fat footprint through the earth (the entire Earth, I suppose) - but the effect your and my little circuits will have will be so dwarfed by all that geoelectric flux that you can't really ascribe any given current flow through the earth to us. This ground-earth return thing worked, for a while, but the telegraph switched to two-wire (i.e. they provided their own return), I think because the impedance of the whole circuit was too high to prevent higher frequency transmissions (or reliable transmissions over very long lines). Britannica has an article about this, but I think Wikipedia doesn't (that I can find). -- Synthetic element 17:50, 26 June 2007 (UTC)

This is the answer I was looking for, thanks. I think I understand your infinite repository idea. I just need to get my head around how a bit of metal stuck into the soil can draw on infinite amounts of charge, when it probably doesn't make a very good connection to the earth. Does it rely on water in the soil, and whatever electrolytes are dissolved in it? Alf Boggis 19:13, 26 June 2007 (UTC)

Although the resistance of the earth is high, there are so many paths that, after the resistance near the exit and entrance, everything else becomes quite small. It is common for part of an electric circuit to be grounded, which would be pointless if it was so difficult to get electricity through there. — Daniel 18:42, 26 June 2007 (UTC)

Another way to look at it: the resistance of a wire is inversely proportional to the cross-sectional area. This "cross sectional area" for two electrodes sufficiently far apart would be the area of successively larger subterranean hemispheres centered at the electrodes. Thus the resistance would be an integral of 1/r^2, starting with an r that gives the area of the electrode surface and going to infinity, and multiplied by some "constant" for local rock/soil/groundwater properties (and for the 2*pi/3 area of the hemisphere). As has been pointed out, you'd also have to put a voltage term in that leg of the circuit too, generated by the earths magnetic field or whatever, not to mention impedance/capacitance. This model is too rough for real calculation, but it gives an idea of the relevant variables - the one you control is the surface area of your electrode, ie, how deep you drive your grounding rod. With a deep enough rod (or various rods spaced more than their depth apart), you can get essentially arbitrarily small resistance. --Homunq 19:31, 26 June 2007 (UTC)

A pair of ground rods many thousands of miles apart would be able to source or sink an amount of DC current from a single wire connecting them and a source of current which depended on the resistance achieved in the grounds and of course the internal resistance and voltage of the power source. The resistance of a ground rod depends on the soil conditions and the depth to which it is driven. Sand or rock make for high resistance, and soil (especially if damp) makes for lower resistance. Utilities use stainless steel rods which they drive into the ground, then screw on another, and keep going until the required low resistance is achieved. 30 feet deep is common to get the resistance below ten ohms. (The following is presented only as an illustration; do not try anything like this at home, because of the danger of electric shock). So if you had 2 ten ohm ground rod installations, and a 1200 volt DC source, and another 100 ohms resistance in the connecting line (and the voltage source, such as a generator or battery) the current would be 1200 volts divided by (10+10+100)ohms = 10 amps. Increase the voltage to 12,000 volts and you would get 100 amps. Etc. This could of course increase the rate of corrosion of metal objects in the ground near one of the ground rods, and it might heat up the ground rods unless they consisted of several in parallel. It might also dry out the ground and increase the resistance, or it might set up a ground potential causing dangerous shocks if someone stood near the rod, something like lightning hitting a tree and killing someone standing near it. Electric utility installations use a great number of ground rods spread around the facility and bonded together. There are also earth currents of electricity caused by sunspots and other phenomena which can cause large currents under certain conditions. Between two rods the current takes every possible path. Dirt (or rocks, or sand) has a certain resistivity, so more parallel paths just means lower resistance. Inventors such as Samuel Morse and Nathan Stubblefield used rods stuck in the ground to send and receive wireless telegraph and telephone messages respectively, in the 19th century. Edison 21:47, 26 June 2007 (UTC)

Synthetic element, the article you couldn't find is Ground (electricity)#History. There is a short section on ground returns, but it could do with more detail. --Heron 09:21, 27 June 2007 (UTC)

Acupuncture and Hypnosis

Everyone speaks ambiguous about these two. Do they really work? I hate pseudoscience. --Taraborn 19:18, 26 June 2007 (UTC)

We have encyclopedia articles on acupuncture and hypnosis. Friday (talk) 19:21, 26 June 2007 (UTC)

I'm aware of their existence, but apparently they did not answer my question. --Taraborn 22:27, 26 June 2007 (UTC)

To my knowledge, both have been proven to work, but not necessarily on the wide range of claims or on the kind of scale some practitioners claim. In particular, hypnosis is more like a combination of deep meditation and increased suggestibility, rather than some kind of mind controlling power. Confusing Manifestation 22:48, 26 June 2007 (UTC)

It's pretty clear that to the degree that acupuncture does work, it's operating by the placebo effect. It's kinda hard to do a controlled experiment though - merely pretending to stab people repeatedly with needles as a control is a bit tricky! However, the placebo effect is undoubtedly a real, scientifically proven thing - and harnessing that effect with all of the theatre and drama associated with sticking needles in just the right place appears to benefit some people with some conditions. It's pseudo-science because it claims to work in ways that it cannot possibly - but that doesn't stop it from working anyway! Hypnosis is a bit more controversial - I'm not sure what to think. SteveBaker 03:30, 27 June 2007 (UTC)

Saying that something doesn't work in ways some claim it works, because "it cannot possibly" do so, sounds a trifle unscientific. Isn't the scientific approach to observe things that have actually occurred, and explain them? Just because the placebo effect is well described doesn't necessarily mean that that's what's at work with acupuncture. I've no doubt that's the operative agent in some cases, but does it explain all cases? -- JackofOz 04:04, 27 June 2007 (UTC)

Well, this strengthens even more my statement that everyone is ambiguous about this topic. Since intelligent people aren't sure about whether they are scientific or not, I'll have to guess that both are a pile of unscientific trash. --Taraborn 11:54, 27 June 2007 (UTC)

I'm pretty sure acupuncture works. After all, how else can you anesthetize a patient for an open heart surgery? bibliomaniac15 ^{BUY NOW!} 22:42, 27 June 2007 (UTC)

Acupuncture claims that the needles need to be stuck into acupuncture points or on the meridians for the effect to work properly. Now presumably one scientific test you could do to test the placebo effect would be to apply the same technique, preferably in a double blind trial, to places other than the acupuncture points or meridians and see whether or not you got the same effect.

Note that results of this test would not necessarily be conclusive. For example the acupuncture points may have actually been chosen in a prescientific scientific type way through repeated trial and error to find what points on the body had the greatest effect; they could say be close to underlying nerves and thus stimulate those nerves more directly if an acupuncture point rather than a random point is used. Some ancient memory tells me I have heard of this test being done, and there being no difference found in the efficacy of treatment, but I have no references for this and it could just be my preferred memory of the results.

There's also the point (despite the preceding unreferenced claim from Bibliomaniac) that acupuncture, when it does work, is most effective in treating relatively mild pain. A simple explanation for this could be that sticking needles into your body leads to the release of natural endorphins (which of course it would) and that is the explanation for any effect noticed.

I've written enough, so I won't comment at length on the hypnosis side of the question. Conman's statement about it being a state of hypersuggestibility seems to be quite accurate. Though it can have some uses if done properly, consider for example the significant role of hypnosis in false memory syndrome. --jjron 07:14, 28 June 2007 (UTC)

The problem with the natural endorphin theory of acupuncture is that it also appears (or is widely claimed) to be effective for making people give up smoking. Those endorphins would be flushed out of your system very soon after the 'treatment' - they can't explain any effect that lasts more than a few hours. SteveBaker 21:16, 28 June 2007 (UTC)

I'm sorry, I don't regard 'widely claimed' as scientific evidence of efficacy. Any proof from a reputable study that this is anything but the placebo effect, if in fact there is any effect at all? See smoking cessation that claims that's all it is. And perhaps if this is the method for quitting smoking that they are relying on in China, that would explain why China is now one of the largest and fastest growing markets for smoking. --jjron 09:51, 29 June 2007 (UTC)

Well, yes - I should probably have spelled out the four possibilities in detail:

1. Acupuncture has no effect whatever on people - it doesn't have to be 'explained'.
2. Acupuncture has no significant physical effect on the body in itself - but people do get benefit from it - which means we're looking at a placebo effect.
3. Acupuncture does have some significant physical effect - and it's beneficial.
4. It's magic.

In my opinion, there is enough anecdotal evidence that (1) is not the case. It's truly impossible to believe that the entire medical system of an enormous country like China over 3,000 years could have been based on something that has absolutely zero effect on people. According to our article on acupuncture, some serious scientific studies from the World Health Organisation have shown that it does have a clearly measurable effect (although maybe only a placebo effect). So - we must discount (1).

This is the science desk - so we'll just ignore (4) because it's unfalsifiable.

So we're left with placebo (2) or some poorly-understood - but 'real' - biological effect (3). I asserted (2) - User:Jjron asserts (3) and produces the good old endorphin theory for how that could be. I simply maintain that *IF* there is an effect (which is a consequence of denying (1)) then endorphin production as a consequence of inflicting minor damage on the body can't possibly a valid theory for how that is. Endorphins simply don't last long enough within the body to explain many of the effects widely claimed by practitioners of the art. Endorphin chemistry is well understood and the stuff is metabolised away far too soon to produce long-term consequences for the patient. Ergo, the endorphin theory is BUSTED for most of the claims made for acupuncture. That doesn't mean that there isn't some other theory that might turn out to explain (3) - and it certainly doesn't mean that I believe (3).

The placebo effect is well known and documented. We know that you can cure some pretty significant health problems with a sugar pill providing you convince the patient (and perhaps also the doctor) that it's really a wonder drug. If you give them the same pill and tell them that it's sugar candy - they simply don't get better. This ability of the human body to fix a wide range of problems on it's own IF the patient can be convinced that it's going to happen means that acupuncture could very easily have no significant effect on the body - and yet be more effective than a sugar pill at eliciting the placebo effect. In fact, it would be very surprising indeed if it did not produce a placebo reaction because telling a patient almost anything that they'll believe (eg "The power of prayer") turns out to help them. I don't think we need any more explanation than that - but it's a sufficiently powerful technique that's been used by billions of people over three millenia - we really can't ignore it. The greatest concern is that if we did manage to utterly, scientifically and convincingly prove that it has no direct biological effect (beyond placebo) then we might actually destroy it's ability to produce a placebo affect at all - and that's a bad thing! SteveBaker 15:27, 29 June 2007 (UTC)

Must correct misattribution - jjron never asserted SteveBaker's (3). In my initial post I didn't mention the placebo effect as it had already been discussed. I clearly stated that when acupuncture does appear to work it is typically "in treating relatively mild pain" and then offered an alternative possible minor biological explanation for any observed effect - I fail to see how this is a "significant physical effect", beneficial or not. When the apparent other SteveBaker then claimed it worked for quitting smoking, I then did in fact refer to the placebo effect in my second post.

Two other things to note. Firstly, the placebo effect is a very real effect, but can be oversold or used as a cop-out by simply being invoked to explain anything we cannot or do not yet understand, or do not want to believe. For example, taken from the other extreme, I have heard anti-immunisation campaigners claim the beneficial effects seen through immunisation are merely a result of the placebo effect. Tests can be conducted for the placebo effect, and I in fact suggested one such possible test for it with acupuncture in my first post (largely because Steve suggested in his first post that you couldn't test for it). In general, I try to think of possible biological explanations for treatments that are claimed to be effective but don't seem logical, rather than immediately crying 'placebo effect'.

Secondly, Steve says in his final sentence that utterly proving acupuncture doesn't work could destroy its ability to produce an effect. For starters, I don't know why that's a bad thing, but more importantly, it's not correct. Since when did utter, scientific, convincing proof stop people believing nonsense things? Take the level of belief in astrology. Take the 86% of Americans that believe in some type of creationism, and the 46% that believe in its most extreme form (from here in the creationism article). Remember, this is an apparently highly educated first world society believing in a prescientific myth in preference to one of the most well proven scientific facts we have.

Sorry, most people just aren't swayed by scientific arguments unless it's of some personal benefit to them. For a huge percentage of the population, if they want to believe in some nonsense, they'll believe it regardless of whatever proof they're shown to the contrary. --jjron 11:52, 30 June 2007 (UTC)

bentonite

Does anyone know how to remove trace amounts of bentonite from oil? Essentially, I need something that will bond with the bentonite molecule to make it heavy enough to be removed with a centrifuge.

Thanks

facial gymnastics and face lifting

is facial gymnastics a valid 'treatment' and is it true that current facial plastic surgeons use it in the recovery process? or does it not work at all? i can't find much info online.thank u!

Are you referring to gurning? ;) --jjron 07:22, 28 June 2007 (UTC)

Tongue pickier than nose?

Why does just about everything that tastes good also smell good, but many things that smell good taste awful? 209.53.180.167 22:22, 26 June 2007 (UTC)

To expand this: is there an evolutionary reason why flowers smell good to humans, or is it just an evolutionary accident? A.Z. 22:43, 26 June 2007 (UTC)

Maybe our tastes are more similar to bees' than we think. --Taraborn 11:56, 27 June 2007 (UTC)

I don't have a reference, but it seems sensible that things that smell good are things you might try eating, whereas things that taste good are things you'll keep eating. So it makes sense that more stuff would smell good than would taste good. Friday (talk) 23:02, 26 June 2007 (UTC)

fish sauce and parmesan cheese. But yes in general I agree. Vespine 23:13, 26 June 2007 (UTC)

One simple reason is that when you taste something, you're also smelling it. (Which is why things don't taste right when your nose is blocked.) --Anonymous, June 26, 2007, 23:33 (UTC).

Stinky tofu, papaya, Century egg... There's actually a lot of good food that smell bad. Very bad. Never had a durian myself.... --Wirbelwindヴィルヴェルヴィント (talk) 07:06, 27 June 2007 (UTC)

When we "smell" something, we are detecting a volatile molecule by activation of our olfactory epithelium. Volatile molecules tend to be small and if something isn't vaporised, we can't smell it. However, molecules that we taste do not need to be volatile, since our taste buds can come into direct contact with non-vaporised compounds. Therefore since the molecules we are actually detecting can be very different, its not surprising that things that smell "good" do not always necessarily taste "good". Of course, even if we are detecting the same chemicals through both modalities (and in some cases we are), then it doesn't follow that the same molecule gives the same general emotional response. This is because taste receptors and olfactory receptors are different, and they project to different brain regions.

However, you are correct in noting that things that taste good generally smell good, but the opposite less so. This is because what you are calling taste is more complex that you may think. In fact, when you say something "tastes good" a large proportion of that sensory signal is actually smell, though you may not realize it. So when something tastes good, that in itself is because it smells good. Consider the difference between the flavor and the basic taste of a substance.

As for A.Z.'s question about evolution, well, thats a good question to which we don't know the answer. In animals, certain natural plant odors appear to activate the vomeronasal organ (VNO), which appears to control hardwired, innate responses. In this paradigm, one could hypothesize that there is an evolutionary reason that these animals respond to pleasant smelling plants in a positive way i.e. that the odors are kairomones. However, humans don't have a VNO, and we don't appear to have the same mechanism to permit us to respond to odors in an innate manner (there is no strong evidence for human pheromones). So when we detect odors the signal is is projected to areas of the brain where we can process, associate and attribute information, rather that simply react to it in a pre-programmed way. Indeed, one would imagine it would be entirely possible that some people do not enjoy the smell of flowers, because their brain associates it with something unpleasant. So, the interesting question is why is it that, in general, some smells do appear to be pleasant to the population at large. Is it innate, or just associative? If its the former, how does the neuronal circuitry mediate such a response? These are questions that are very interesting to the olfactory research community, because smell is such an emotionally meaningful sense that having the ability to understand how we can generate such powerful attractive stimuli would make someone a lot of money indeed. Rockpocket 07:46, 27 June 2007 (UTC)

Eyes Very Sensitive to Bright Light

Over two years ago I underwent the Lasik eye procedure to correct severe nearsightedness. It worked pretty well for what it was intended, but ever since then my eyes have been very sensitive to light from the sun and unshielded lightbulbs and even the computer monitor. Going outside without dark sunglasses on for more than fifteen minutes results in a pounding headache, and even with the glasses I find it painful to face the sun with my eyes closed. I have tried to ignore this in the hopes it would go away eventually, but it has become obvious that if I don't do something I'm going to have a headache most days for the rest of my life.

I know we're not supposed to ask for medical advice here, so I was just wondering if anybody knows of a type of vitamin or nutritional supplement that can help alleviate this problem somewhat. Even a little help would be appreciated.

And I don't have insurance or a job, so consulting a doctor is a last resort here. Thanks very much. Danthemankhan 23:00, 26 June 2007 (UTC)

I really doubt there is any nutrient or vitamin that can address that problem specifically. If anything oral could, it would be a drug or an eye drop... and I currently only know ones that dialate the pupil to let in more light (which is the opposite of what you need) and Wikipedians are generaly not qualified to prescribe such a product to you anyway. I suggest you go back to the doctor who performed the surgury. Post-operative care is usualy included in the operation price, however I don't know about 2 years later. Anyway, why haven't you addressed this problem earlier? Hasn't it been like this since 3-6 months after the surgury? (3-6 months is usualy quoted as when your eyes have completed recovering from surgury)? 209.53.181.30 02:47, 27 June 2007 (UTC)

If you don't like putting your shades on and off maybe you should invest in transition lenses that automatically dim according the ammount of light they are exposed to. Then again, you probably got the surgury done to free you from eyewear... 209.53.181.30 02:49, 27 June 2007 (UTC)

If money is an issue, you could always consult a lawyer instead to see if you can sue a doctor ;-) Someguy1221 02:59, 27 June 2007 (UTC)

Have you considered tinted contact lenses? They may be available in a null curve, to act as a sort of permanent shade for your eyes. This is not medical advice and you should surely see a doctor for more information. In a more creative approach, maybe you should consider moving to a region known for cloudy days? --Jmeden2000 16:30, 28 June 2007 (UTC)

I don't want to trivialize what is obviously a painful and distressing condition, but I do feel glad to live in a country with socialized healthcare. DuncanHill 16:44, 28 June 2007 (UTC)

At the same time, in the US you are one hospitalization away from an $80,000 bill the hospital will never stop hounding you to pay, and there goes the college fund or your retirement plans. It's like a kidnapper demanding ransom. Of course if you are poor, the government pays. If you pay thousands a year for health insurance, the insurance company still picks out some procedure a surgeon did and says it is not covered because it is "not medically necessary" even though the surgeon found it necessary, and you have to pay thousands out of pocket for it after the fact. The US has socialized health care for the poor and many in the middle class are one hospitalization away from bankruptcy. (Now putting away the soapbox which DuncanHill so kindly got out). Edison 13:41, 29 June 2007 (UTC)

Three cheers for the National Health Service. Maybe that accounts for the large number of American women on Craigslist or Gumtree who are seeking a relationship with a Briton.

Hayek's Law: every political intervention in the marketplace creates distortions which create demands for more intervention. Since medicine is (at least in These United States) the most heavily subsidized and regulated industry of all, with the taxpayer already picking up almost half the tab, it's no wonder that there's a perennial clamor for government to monopolize what it has merely crippled. —Tamfang 22:10, 1 July 2007 (UTC)

When I tried contacts in 1982 (didn't work out for me), I was warned of two effects: light would seem brighter, because glasses gather less of it, and my eyes would be drier, because glasses reduce the evaporation of tears by partially trapping the moisture. I'd expect similar effects from Lasik, but it's surprising that the effects haven't gone away in two years. —Tamfang 06:49, 3 July 2007 (UTC)

Miosis mentions that pupil-constricting drugs do exist (just start taking your nightcap first thing in the morning? j/k). List of eye diseases and disorders does not, to my untrained-as-a-medical-doctor eye, contain anything particularly worrisome in your case, but photophobia has some kinda frightening possible causes for light sensitivity, including retinal detachment and meningitis. Vitamin A is the only vitamin of which I know offhand which affects vision, but the symptoms of deficiency include night blindness and corneal degeneration, not photosensitivity. Besides, it is fat soluble and overdose looks kinda scary, so do not try to load up on that unless you consult a doctor. On a lighter note, a little original research indicates that I think my eyes strive more to shield themselves from the horror that is the blazing sun after spending a number of days almost exclusively indoors or outside only after sunset. -24.177.183.47 21:00, 2 July 2007 (UTC)

Survival of the fittest - winner

So survival of the fittest has been going on for a while, and it's still going on today, so today I wondered about a über-fit animal that could be the product of said proccess. The animal would be able stay alive by getting food and avoiding being eaten, killed by competitors, or hurt in an accident. Any ideas of attributes this theoretical animal would have? - AMP'd 23:04, 26 June 2007 (UTC)

I'm not sure there is any such thing as "über-fitness". First, the things you mention mostly require lots of energy to be done extra well. That means that a creature that could do them well would probably need lots of food, which would, in one sense, make it less fit. Second, in the context of evolution, "fitness" does not necessarily mean that individuals are good at surviving. Rather, it means that the species survives. One way to do this is to make individuals good at surviving. Another way way is to make lots of relatively fragile individuals that reproduce quickly and in large numbers. (Consider insects.) --Tugbug 23:23, 26 June 2007 (UTC)

Take a look at the herring gull. It's an excellently-'designed' beast. It's strong, it's incredibly fast, it's smart, it's aggressive, it has excellent eyesight, it's large and formidable enough for most predators to decide give it a miss and look for an easier meal, it's long-lived, it can fly (both strong, powered flight and gliding), it can swim, it can run, it can hunt, it can scavenge, it can eat just about anything organic - even decaying matter filled with toxins, it can survive drinking salt water, it can breed just about anywhere - *and* it's sussed out how to exploit humans without ever becoming too trusting. I get a feeling that if anything bad ever happened to the world, there would still be herring gulls left standing at the end of it all. --Kurt Shaped Box 23:26, 26 June 2007 (UTC)

To a certain extent, being fit is relative to current environmental conditions. Not being specifically familiar with any given species, the gene pool may be susceptible to attack by a certain disease, and there are other concerns as well. Succession is an ongoing process that can turn today's winners into tomorrow's losers in any given habitat or ecosystem. –Pakman044 23:41, 26 June 2007 (UTC)

Just to give a good example, and explain further, you also have to look out for the odd population bottleneck, like a meteor impact. Show me a mutation that will make an uber-fit animal survive that. And similar to above, after such an event, nice genes to have might be ones for being able to travel long distances (to someplace that didn't just have its ecosystem wiped out by the heavens), and subsequently being able to eat different foods. Similar to being able to resist a particular strain of disease, some of these genes can be completely independent of ones that made them "fit" in their prior environment. Modern human examples of such genes (alleles, or whathaveyou) would be the sickle cell trait (increased resistance to malaria), and cystic fibrosis (increased resistance to cholera, hypothesized but not confirmed). In the absence of rampant infection by these two diseases (and especially before modern medicine), the accompanying mutations would normally be considered to decrease ones "fitness." Someguy1221 02:58, 27 June 2007 (UTC)

Flying is an energy-intensive activity, requiring easy availability of high-energy-density foods. If the world's supply of food energy were to drop (say, from a meteor-impact dust cloud), your gulls would have a hard time. Either they'd switch over to swimming and running, which leaves them vulnerable to energy-conserving ambush predators, or they continue flying and starve to death. --Carnildo 22:15, 27 June 2007 (UTC)

The gulls would eat the cockroaches. Plenty of protein there. :) --Kurt Shaped Box 16:14, 29 June 2007 (UTC)

It's a mistake (and a common one) to assume that evolution is a process that slowly makes better and better plants and animals without end. That's really not true. At any given time, it's more or less true that all of the animals and plants are the best that they can possibly be for the environment they are in. In environments where the conditions don't change much, the species stay pretty much stable. Evolution happens surprisingly quickly when conditions change - but the evidence is that each lifeform fits into it's environment as best it can in short order. So it's possible that a future sudden change in the environment (global warming maybe) might result in adaptations, the creatures that result might well not be suited to our present situation - and we not to theirs. SteveBaker 03:07, 27 June 2007 (UTC)

Per the comment above me, see also punctuated equilibrium. Someguy1221 03:12, 27 June 2007 (UTC)

And red queen, with respect to predator avoidance. Bendž|Ť 07:47, 27 June 2007 (UTC)

Bottom line is that a major survival feature is adaptability. If something is so good any changes are weeded out, then when the environment changes, their descendants will be disadvantaged. Of course, the retroactive proof by evolution comes into play here; after a billion years, if we haven't seen anything superior to what is alive now, then there probably can't be anything superior to what is alive now, given this need to be able to further evolve from here. Gzuckier 14:32, 27 June 2007 (UTC)

Shark. Top of the food chain, older than the dinosaurs. Gandalf61 19:46, 27 June 2007 (UTC)

And many species of sharks are near extinction today... --V. Szabolcs 07:02, 28 June 2007 (UTC)

To really do what Amp'd asked would require an organism that could control its environment, essentially produce food at will, be largely unaffected by extremes of weather, destroy or control any natural predators or competitors, be able to avoid injury or disease, or mend itself if it was injured or became sick. I'd suggest to achieve this, rather than typical physical attributes we think about, rather it would need a very big brain to allow it to adapt to changes and come up with solutions to problems that it faced very quickly. Now, it just so happens that such an animal has evolved once in the Earth's history, and we call them humans. --jjron 07:37, 28 June 2007 (UTC)

I've found some interesting thoughts about this question "Evolution has no direction. If a species can survive and reproduce better by becoming simpler and stupider, then that is what will happen. There is no endgame to evolution. There are no points for intelligence or complexity." [9]

Timekeeping

Why didn't an ancient Roman or Greek simply create a pendulum out of a string and a weight and have a slave swing it and count the oscillations?

Because they didn't think of it? Or maybe someone did, but didn't think it interesting enough to make public, so we never heard about it. I mean, it's not as if there weren't hourglasses and sundials and things if it was so important to know what time it was. And a pendulum wouldn't be very accurate if a human had to keep swinging it. --Anonymous, June 26, 2007, 23:36 (UTC).

I think you've got it. When you don't have rapid long distance communication ("I'll call you at 3:00") or travel ("The stagecoach leaves at 4:00"), exact timekeeping isn't nearly as important. As it is, I know the time to (if I wish) a precision of much less than a second but I still can't tell you when the traffic will let me get home for dinner.

Atlant 12:49, 27 June 2007 (UTC)

As I recall, it was Galileo who first noted that the period of oscillation was independent of the arc of the swing, so it's possible they didn't do it because they thought it would be inaccurate. - Akamad 00:52, 27 June 2007 (UTC)

Right - before Galileo, nobody realised that the period of swing of a pendulum is independent of how hard or how far you swing it...it is a little surprising that this is the case. So they simply didn't realise that this was a good way to make a clock. It's surprising that such a simple observation had never been made before (or if it had - that nobody tried to make pendulum clocks) - but they didn't. They had quite accurate water clocks as well as hourglasses and sundials. SteveBaker 02:59, 27 June 2007 (UTC)

It isn't independent; that's just an approximation. See pendulum (the bit where the date 1673 is mentioned). This doesn't matter too much for clock purposes because the pendulum (or balance wheel) is driven by a mechanism, which can be designed to deliver a fixed force. Before this design feature was developed, though, spring-driven clocks would change speed as the spring ran down and the pendulum was driven less far. --Anonymous, June 27, 2007, 04:56 (UTC).

Among other things, having detailed knowledge of the time wouldn't have been all that useful, especially compared to the various other labors a slave might do. Dragons flight 07:59, 27 June 2007 (UTC)

I was thinking that it would be quite charming to have a (modern) "clock" making use of a scantily clad model, as a promotion for a business. I would have thought that the ancients would have liked the idea, too, for the same, reason.

A recent issue of the New Yorker magazine had an article about the Antikythera mechanism. The article explored the general topic of ancient technology, pointing out how we don't really know much about it. We know that the ancient technology included apparently sophisticated mechanical automatons, and there are surviving references to technical texts and devices, but essentially none survive. The common assumption is that the ancients had various kinds of "crude" technology, but not things like clockwork-precise toothed metal gears. And certainly not spring-driven gear trains that could be used to build things like mechanical clocks. But, at least according to this article, these assumptions have been increasingly questioned, with the Antikythera mechanism being a fragment example of the kind of gear train technology known. The article goes into reasons why other ancient technology of this kind has not survived. Also mentioned is the theory that the ancients did not use machines for "practical" purposes but rather for "amusement", because with slave labor there was little incentive for "useful" machinery. This theory is, of course, just speculation. The point is that the ancient Greeks and Romans may well have had good clocks and other such devices. In ancient Athens there was apparently something called the Tower of the Winds, which is generally assumed to have been some kind of water clock, but we really don't know what kind of a clock it was. It must have been a water clock because the ancients did not have mechanical clocks, right? Finally, after the fall of the Roman Empire it seems that whatever sophisticated clockwork tech knowledge there was, it was lost in Europe. But in the Islamic world there are known examples of mechanical clocks and other devices dating back practically to ancient times (see Clock#Early mechanical clocks). There is a theory that ancient clockwork tech survived in the eastern Roman empire and the Islamic world that replaced it; and that the Renaissance-era European "inventions" of precise gears and clockwork were essentially transmissions of technical knowledge from the Islamic world, similar to how ancient philosophical texts were transmitted to Renaissance Europe via Arabic.

Anyway, it looks like the article is available online. Pfly 05:07, 28 June 2007 (UTC)