Wikipedia:Reference desk/Archives/Science/2011 July 20

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July 20

Strange chemical nomenclature

Is another name for 2-hydroxycarboxylic acid: 1,2-dioxidanyl-1-oxidanylidenealkane? Plasmic Physics (talk) 07:56, 20 July 2011 (UTC)

2-hydroxycarboxylic acid is a generic term for carboxylic acids with a hydroxy group on the carbon next to the COOH acid functional group, such as lactic acid. Did you just make up these terms: oxidylidenealkane or oxidylidene and dioxidyl as they seem to be little used or not at all? Graeme Bartlett (talk) 11:24, 20 July 2011 (UTC)

I just made a minor modification.

I constructed the name based on substitutive nomenclature for naming molecules not containing oxygen, using sulfur and hydrocarbons as a model. Oxidane/sulfane, oxidanyl/sufanyl, oxidanylidene/sulfanylidene. My point is, I did just make up these terms, but I based it of existing nomenclature rules. Is my method right? Plasmic Physics (talk) 11:38, 20 July 2011 (UTC)

Moreover, why is it that group 14 substituents only use -yl and not -anyl, as in why is it methyl, silyl, germyl, and not methanyl, silanyl, germanyl; and why is it sulfanyl, selanyl and not sulfyl, selyl? Plasmic Physics (talk) 11:53, 20 July 2011 (UTC)

• Some of this stuff is historical, and some of it is plain arbitrary. That is, there needs to be some system that we all agree on, but don't always look for that system to be completely, strictly, 100% constructed so as to obey certain "rules" and never require actually memorization of some things. Usually, to construct the "side-chain" version of a neutral molecule, you drop the "-ane" part and add "-yl", thus methane becomes methyl and silane become silyl. Sulfanyl isn't a very common term, most sources use thiol instead, excepting when refering to the "sulfanyl radical", though even then many would just say "thiol radical". There is no "sulfane", excepting perhaps hydrogen sulfide, which no one ever calles "sulfane". Just remember that chemical nomenclature is itself a subset of linguistics, and as in any other language, is subject to arbitrary exceptions to core rules, as well as change over time and differences in usage among speakers; i.e. there are chemical "dialects" where you find different sources using different terms for the same thing. It happens; if the Académie française cannot have perfect control over every person speaking French in the world, the IUPAC cannot likewise have 100% control over chemical nomenclature. I've rarely met a chemist who uses terms like "ethanoic acid" or "ethyne" instead of the more common acetic acid or acetylene. --Jayron32 15:52, 20 July 2011 (UTC)

Regardless, is the method that I use to construct the hypothetical name correct? I'm still not sure how IUPAC made their decision regarding -anyl v.s. -yl. Plasmic Physics (talk) 01:07, 21 July 2011 (UTC)

Using the same method for naming 1-(methylamino)propan-2-one, what would be its name?

1. 4-oxidanylidene-2-azapentane
2. 2-aza-4-oxidanylidenepentane
3. 2-oxidanylidene-4-azapentane
4. 4-aza-2-oxidanylidenepentane

If there is an in-chain substitution, does it automatically precede the parent name, or is it listed alphabetically along with other on-chain substituents. Is chain numbering determined by the in-chain substitution first, and on-chain substitutions second?

FYI: 2-thiapropane is an acceptable alternative name for dimethyl sulfide. Plasmic Physics (talk) 01:38, 22 July 2011 (UTC)

Look, strictly speaking there is exactly one correct IUPAC name for any molecule. For some molecules, especially those that predate the IUPAC standards, there are older names which persist. If you are going to invent your own system of nomenclature, you can't then ask us if it is "correct". The IUPAC name is the only correct name; excepting if there is an older or "common" name. Coming up with new names on your own isn't "correct". --Jayron32 01:43, 22 July 2011 (UTC)

I'm not inventing my own system though, I'm just being indifferent towards exceptions. The system I'm using already exists, but are only used conditionally, as in it is only used in certain conditions. I'm attempting to use it in a universal way. (AAA)ylidene- exists, (AAA)a- exists, I just want to find out the rules of use, without exception. Plasmic Physics (talk) 02:00, 22 July 2011 (UTC)

You aren't being indifferent towards exceptions, you're being indifferent towards some arbitrarily selected rules. Exceptions, in this context, aren't "violations of the rules we allow", they are simply "more rules". Those rules have their own conditions of use. To ignore them willy-nilly is arbitrary, and is inventing your own system. If you follow the IUPAC rules for naming the compound in question, you get one name, and that's it. If you get a different name, it means you (either willfully or accidentally) ignored or misapplied some of the rules. Yes, there are places where a phrase like "oxidanylidene" may be needed. This molecule is not it. I mean, take a compound like "2-methyl-1-butene". I suppose I could try to name it "2-ethylpropene". I'd be wrong, because I didn't follow the rules. What you are doing is no different than that, you're just using more obscure functional groups. --Jayron32 02:10, 22 July 2011 (UTC)

Good, well, I told you which rules I'm not using, are the rules that I am using being applied correctly? Plasmic Physics (talk) 02:28, 22 July 2011 (UTC)

Anyone have an answer? Plasmic Physics (talk) 15:13, 24 July 2011 (UTC)

Walter Lewin's circular track experiment

Walter Lewin performs a demonstration at the end of his thirteenth lecture (Potential Energy - Energy Considerations to derive Simple Harmonic Motion) in his Physics I: Classical Mechanics online lecture series which can be found here: http://itunes.apple.com/itunes-u/physics-i-classical-mechanics/id341599916 At the very end of the lecture, he asks why the empirical period of oscillation is substantially longer than the predicted period. You can see the amplitude decrease over time, but he dismisses friction as being the cause of the increased period. My only other theory is that the second track is not truly circular, instead being the arc of an ellipse or some other curve. Can anyone enlighten me? Widener (talk) 10:42, 20 July 2011 (UTC)

I have not listened to the lecture, though I would hazard to guess that the cause of the periodicity dampening (how did I know the meaning of that term?!) is caused by some effect tangentially relevant to effects of inertia within the system (perhaps related to the centripetal/centrifugal forces caused by the circular track itself?). ~AH1 ^(discuss!) 20:10, 20 July 2011 (UTC)

Chocolate question

Dear Refdeskers, I have a question and I need just a simple answer (no maths). Say you have two plain chocolate bars (for all intents and purposes they are identical). Now, take one and melt it (any way - i. e. by unwrapping it and placing it in a bowl, so that sunlight can melt it, or put the bowl with the chocolate in some warm water and wait until it melts). Now, between these two bars (one molten and the other one not) is their calorific (caloric?) value equal or different? If different, will the molten one have a higher energy value because some energy was expended upon it in order for it to melt? I kind of have a hunch the molten one might just be higher on calories because of this, but it's just a hunch. So, anyone? No maths required (or physics, or chemistry), just a 'yes', 'no', 'maybe' or 'you have waaay too much free time' will be enough. Cheers and thanks! --Ouro (blah blah) 12:32, 20 July 2011 (UTC)

In terms of food energy, the difference between the two bars will be negligible. It takes energy to break bonds, so technically the melted bar would have slightly (but not in a way that is measurable or would affect your body) higher food energy due to the broken intermolecular bonds in the phase change between solid and liquid. Here is the caveat, however, that those selfsame bonds would have been needed to be broken anyways when you ate and digested the chocolate, so the effect in terms of how much net food energy you get from the bars would be essentially identical. What you have basically done when melting the chocolate is "pre-digested" it by a small amount. --Jayron32 12:43, 20 July 2011 (UTC)

(ec)Here is a "yes, but" ;-). Molten chocolate has a nominally higher energy content, but for nutritional purposes, the chemical food calories completely dominate. Normal chocolate has about 5000 Kcal/kg. That's enough to raise the temperature of one cubic meter of water by 5 degrees, or to boil approximately 8.5l of water starting at room temperature. I don't know the enthalpy of sublimation for chocolate (and I suspect it's ill-defined anyways), but it is a lot less than the chemical energy. --Stephan Schulz (talk) 13:02, 20 July 2011 (UTC)

I think I like Jayron's answer more because he kept to the 'no maths and others' rule :) but thank you both! --Ouro (blah blah) 19:39, 20 July 2011 (UTC)

True, but why would you add such a completely unnecessary rule to a question which is best answered through the use of math? Dauto (talk) 19:57, 20 July 2011 (UTC)

Maybe because it's hard to understand that 1 + 1 = 2 is not math :) . ~AH1 ^(discuss!) 20:05, 20 July 2011 (UTC)

100 g molten chocolate has about the same energy as 101 g of not molten chocolate. (the food energy is 5000 kCal/kg = 21000 kJ/kg, the enthalpy of fusion is about 200 kJ/kg. That's 1%). Bo Jacoby (talk) 20:47, 20 July 2011 (UTC).

I just wasn't in the mood for maths, I wasn't feeling 'let's inspect it thoroughly' but I was just wondering whether it is as I thought it was. Seeing that the differences are rather negligible (okay, I admit, it was useful to use numbers for this) I am quite happy. Thanks Bo and thanks all around! Curiosity satisfied. --Ouro (blah blah) 04:59, 21 July 2011 (UTC)

Flattening coins on railway tracks

Specifically, the reason I'm not supposed to do it. Of course I've done it as a child, both on train and tram tracks, and know very well it won't derail a train. But I have a vague recollection of a railway official (in Finland) explaining that a coin on the tracks can cause a dent on the wheel and that this is a Very Bad Thing as it will progressively get worse as the train keeps running, and soon enough the expensive steel wheel will be ruined. Now since a bit of googling fails to turn up any similar warnings concerning this fairly popular amusement, I get the feeling that the damage from a coin to a train wheel can't really be a big deal - there's bound to be all kinds of little stuff on the tracks anyway, never mind the huge gaps in old-fashioned tracks, points etc... I think they were just trying to keep people from playing on the tracks. It would be a clever ploy at that: even people who are pretty careless with their own safety are often reluctant to damage other people's property. But then I don't really know for sure. What do you say, can the damage to trains (or tracks) from flattening coins be at all significant?--Rallette (talk) 12:45, 20 July 2011 (UTC)

My view - pretty much for the reasons you state - is that a coin is unlikely to do much more damage than, for instance, fish-plated joints in rails. I suspect that most coins are of a very much lower hardness than the wheel. --Tagishsimon (talk) 12:54, 20 July 2011 (UTC)

Before abusing train wheels please observe the Causes of the Eschede train disaster that killed 101 people and remember that train accidents are not funny. Cuddlyable3 (talk) 13:44, 20 July 2011 (UTC)

A lot of rails are electically live, to power the train. Don't encourage kids to both electrocute themselves and perhaps cause a train accident. 2.101.13.9 (talk) 13:59, 20 July 2011 (UTC)

That accident is somewhat unrelated, in that the cause of the accident was built into the train itself, and was not caused by abuse. Plasmic Physics (talk) 14:05, 20 July 2011 (UTC)

From my experience the UK railways in days of yore had signs prohibiting almost everything. I have never seen a sign that said "Don't put your money on the rails", if there was a significant risk I think we would have been advised. ;-) Richard Avery (talk) 14:12, 20 July 2011 (UTC)

From a safety standpoint, I would say that there is more danger to you being in proximity of the train than danger to the train itself (in fact, I would say there is no danger to the train, but that comes with a big fat ). However in the United States, most (if not all) railroads are private property, so putting a penny there would require you to be trespassing. -RunningOnBrains^(talk) 14:22, 20 July 2011 (UTC)

Thanks for all your answers and comments so far. I should add that the railway official I mentioned made no suggestion, so far as I can remember, that flattening coins would in fact endanger the train. The problem was supposed to be the wheels wearing out prematurely.--Rallette (talk) 15:14, 20 July 2011 (UTC)

See [1] and Elongated coin#Process are the first two g'hits I found about it. Lots of others with comments from engineers that a coin (and even slightly bigger/harder things) have no effect. DMacks (talk) 15:19, 20 July 2011 (UTC)

I defer to your superior googling skills - I failed to find any expert opinions one way or the other. Except now that you said it, I googled again and this time with better results. Thanks!--Rallette (talk) 15:29, 20 July 2011 (UTC)

(EC) This strange Indian ref [2] mentions it delaying trains but how isn't explained. This is complicated by the fact it also describes stealing wires from signals to sell which obviously is likely to cause delays. [3] links to MythBusters (2005 season)#Episode SP4 – "MythBusters Outtakes" which mentions this was tested, although primarily concentrating on the derail train myth. (Although in the discovery.com forums ref someone claims a train derailed after they place a whole stack. I find this questionable for a variety of reasons including the fact any derailment would likely have been investigated and the fact it seems unlikely this stack stayed a stack unless it was glued tight.) [4] however claims there was no damage to the train wheels in the MythBusters test.

That and these refs [5] [6] [7] [8] suggest other then the obvious risk of being near a train (and [9] mentions a number of deaths from people trying to flatten coins), a bigger risk may be the coins sometimes/often go flying which could cause injury to anyone nearby (including someone who isn't even aware of the coins and didn't place them).

There is of course a slight possibility that when the train actually runs over a coin (whether it just flattens it or it gets stuck to the wheel) it may cause some very very minor damage so over time, if enough people do it it may cause sufficient damage to affect the lifespan. This doesn't seem that likely but one complicating factor is most of the refs seem to concentrate on the possibility of derailing rather then simply any damage, even very minor, to the wheels or tracks.

BTW, in a few of those refs it's claimed a completely immobile train may be prevented from moving if coins are placed in front of and behind the wheels. Nil Einne (talk) 15:58, 20 July 2011 (UTC)

The danger of coins will depend largely on the type of coin. Antique Swedish "coins" often weighed as much as 15 - 20 kilograms[10]. ~AH1 ^(discuss!) 20:02, 20 July 2011 (UTC)

I wonder what would happen if a diamond were placed on the tracks... Wnt (talk) 20:09, 21 July 2011 (UTC)

You'd end up with a small pile of diamond dust. Diamonds have high scratch hardness, but high brittleness means that a sudden blow (say, from an oncoming train wheel) will shatter them. --Carnildo (talk) 00:19, 22 July 2011 (UTC)

If in doubt, use an old (pre-1982) penny, not a nickel. Copper is much more malleable. Actually one of my favorite memories as a child is of my dad putting a penny on the rails of the Stone Mountain Scenic Railroad and us coming back and inspecting the results.

Race as subspecies

Would it be correct to consider human races on the basis of physiological features as a subspecies of Homo sapiens?--178.182.96.29 (talk) 14:02, 20 July 2011 (UTC)

No. -RunningOnBrains^(talk) 14:14, 20 July 2011 (UTC)

Is there more than one human race with its infinite varieties?Richard Avery (talk) 14:20, 20 July 2011 (UTC)

Human subspecies are unlikely at this time. Our populations mix too well. Googlemeister (talk) 15:03, 20 July 2011 (UTC)

From the subspecies article:

Organisms that belong to different subspecies of the same species are capable of interbreeding and producing fertile offspring, but they often do not interbreed in nature due to geographic isolation or other factors. The differences between subspecies are usually less distinct than the differences between species, but more distinct than the differences between breeds or races (races can be assigned to different subspecies if taxonomically different). The characteristics attributed to subspecies generally have evolved as a result of geographical distribution or isolation.

See also the Race as subspecies section in the Race (classification of humans) article. —Akrabbim^talk 15:28, 20 July 2011 (UTC)

It would not be politically correct. Cuddlyable3 (talk) 17:31, 20 July 2011 (UTC)

It wouldn't be factually correct either. AndyTheGrump (talk) 17:41, 20 July 2011 (UTC)

It would be problematic. There's probably no more or less difference between different human "races" (note the scare quotes) than there is between different subspecies of Canada Goose or any other cosmopolitan organism. The differences between the two concepts are partially biological (humans interbreed much more widely than most other animals due to our habit of immigrating and touring, etc.) and partly social (including the word "species" in there - even within the word "subspecies" - would raise the hackles of those few who are still okay with the term "race") on top of the considerable difficulty in defining what race really means among humans (as someone with a degree in anthropology and archaeology I can tell you that the consensus is "not much"). Using the term subspecies would have one key benefit, though, in that it might hasten the removal of the concept entirely from our view of humans. Matt Deres (talk) 19:00, 20 July 2011 (UTC)

See human evolution. Non-African humans may possess Neanderthal lineage. ~AH1 ^(discuss!) 19:45, 20 July 2011 (UTC)

Given that many humans in Africa (even the ones with dark skin) have ancestors from outside of Africa as well, then its quite likely we all have that same Neanderthal lineage. Given that every single person with one European ancestor at any time in their past are all are decended from Charlemagne, it seems likely that the entire modern human race would have some Neanderthal lineage if any modern human had Neanderthal lineage. --Jayron32 20:22, 20 July 2011 (UTC)

Aside from some isolated groups of course, such as South American Indians with minimal or no outside contact. Googlemeister (talk) 20:28, 20 July 2011 (UTC)

Probably not even them. Given that the settlement of the American continent has been estimated at no more than 40,000 years ago (and that's the fringe outside, absolutely earliest possible date) and that the major period of interbreeding with Neanderthals was between 80,000-50,000 years ago, it seems something of a stretch to say that even among pre-Columbian native Americans, there was not a single Neanderthal ancestor among their entire family tree. --Jayron32 20:42, 20 July 2011 (UTC)

Who is Mr. or Ms. Southern?

I hope this an appropriate question for this page, perhaps it is an idea for an article. I had a look round, skimmed the relevant articles and tried a few searches that were flooded with results.

In a 1914 lecture on the atomic theory, J. J. Thomson said, "But we know that the ratio of mass to weight is the same for all substances, from hydrogen, the lightest, up to uranium, the heaviest, and even, as Southern's experiments on uranium and my own on radium have shown, for radio-active substances." Who is Mr. or Ms. Southern? cygnis insignis 16:08, 20 July 2011 (UTC)

American Men and Women of Science (Gale, 2008) lists a radiochemist by the name of William Southern Lyon, Jr., but says he was born in 1922, so it's clearly not him. Maaaaayyyybe he followed in dear old dad's footsteps? --some jerk on the Internet (talk) 17:45, 20 July 2011 (UTC)

I found [11] from "Transactions of the Illinois State Academy of Science," Volumes 1-4, by Illinois State Academy of Science, page 51, volume dated 1908 (but cites research from 1910, so it may cover multiple years). which discusses "Southerns' experiment," and refers to a scientist named "Southerns" rather than Southern as having done research on uranium. The citation is to "Southerns Proc. Roy. Soc. A. B4 (or "840, 325, (1910). Here is another abstract of that paper, with the citation to "Roy. Soc. Proc. Ser. A, 84, pp325-344, Oct 21, 1910.". So perhaps someone with access to the Proceedings of the Royal Society can look up the researcher's full name. A snippet view from "Chemical news and journal of industrial science," , Volumes 101-102, 1910 indicates the name is "L. Southerns." as author of "Determination of the ratio of mass to weight for a radioactive substance." for uranium oxide. Another article, from "Electrical World." Lots of citations for "L. Southerns, 1906-1910.More results from Google Scholar. His/her career continued for many years. In 1925 was published "Electricity and the structure of matter," by L. Southerns, M.A., B.Sc, Lecturer in physics, University of Sheffield. Apparently he/she was not fond of his/her first name. Edison (talk) 18:02, 20 July 2011 (UTC)

• Finally found that it was "Leonard Southerns." [12]. Here is notice of his 1912 appointment as junior lecturer and demonstrator in physics at Sheffield.Found a 1881 British Census result for a Leonard Southerns, showing him born circa 1878 in Ulceby, Lincoln, England. [13]. Might be your researcher. Edison (talk) 18:24, 20 July 2011 (UTC)
  • I think a Wikipedia bio article on him might be appropriate, since his 1910 research is still regarded as pioneering or important, per "The Attraction of gravitation: new studies in the history of general relativity," by John Earman, Michel Janssen, & John D. Norton, page 176. Southerns did the first experimental test of the equivalence of gravitational mass and rest mass of radioactive substances, confirming they were the same to one part in 2 x 10 ⁵. Edison (talk) 18:34, 20 July 2011 (UTC)

Thank you! If someone creates an article, and the ref is useful, the mention of his experiments can be seen at s:The Atomic Theory#19. cygnis insignis 14:31, 31 July 2011 (UTC)

TCAS reversal

Can you throw more light on the TCAS Reversal technique in the main TCAS article? — Preceding unsigned comment added by 59.161.58.206 (talk) 17:03, 20 July 2011 (UTC)

The appropriate place to check is with your copy of the AIM. You can download that at http://www.faa.gov/air_traffic/publications/atpubs/aim/ or you can read the TCAS Introductory Advisory Circular. For more information, you should probably check with a CFI or your corporate safety director. Nimur (talk) 17:25, 20 July 2011 (UTC)

I just realized that your IP locates outside the United States. This is all the more reason you should probably check with a reliable source relevant to your area. Nimur (talk) 17:53, 20 July 2011 (UTC)

Antimatter black holes?

I was wondering if you had a black hole comprised entirely of matter, and a black hole comprised entirely of antimatter, and then had them collide, would they annihilate, or would they merge into a larger black hole? --Goodbye Galaxy (talk) 19:15, 20 July 2011 (UTC)

They would merge. Black holes have no hair. Bo Jacoby (talk) 19:30, 20 July 2011 (UTC).

You may also be interested in Hawking radiation and gravitational wave. ~AH1 ^(discuss!) 19:37, 20 July 2011 (UTC)

A black hole made from matter is indistinguishable from a black hole made from anti-matter since one of the characteristics of a black hole is the fact that its inside is unobservable. Dauto (talk) 20:05, 20 July 2011 (UTC)

Actually, they do both. "Annihilation" is only distinguished from other physical processes by the fact that the inputs and outputs have zero net charge. A merger of black holes of equal and opposite charge fits that description. Eventually the merged black hole will evaporate into photons and neutrinos. -- BenRG (talk) 20:15, 20 July 2011 (UTC)

OK I am confused. If 1 kg of matter reacts with 1 kg of antimatter you get a whole buncha photons which have no mass, so you converted 2 kg of mass into energy. Now on a black hole, the photons would not be able to escape since the black hole has ubergravity, but the antimatter black hole would remove all the mass and thus all the gravity so it would still be a big explosion right? If not why not? Googlemeister (talk) 20:26, 20 July 2011 (UTC)

Energy=mass. So even if we grant that the two black holes would mutually annihilate, you'd still be left with two black holes worth of energetic photons, causing two black holes worth of gravity. All of the annihilation photons would be created inside of the event horizon, so they wouldn't be able to escape. So you'd have the same amount of gravitation in the same amount of space, which means the event horizon would be the same for a matter+antimatter merger versus a matter+matter merger. -- 140.142.20.229 (talk) 20:53, 20 July 2011 (UTC)

No, not right. Anti-matter has POSITIVE mass and a anti-matter black hole has POSITIVE gravity. BenRG is talking about Hawking radiation. Dauto (talk) 20:59, 20 July 2011 (UTC)

BenRG, the question is not about charged black holes. No need to complicate things more than necessary. Dauto (talk) 21:01, 20 July 2011 (UTC)

I was trying to simplify things by pointing out that black holes behave just like anything else in this regard. -- BenRG (talk) 23:28, 20 July 2011 (UTC)

Kugelblitz (astrophysics) may be a topic relevant to this conversation. The question of whether or not the matter and antimatter mutually annihilate is moot, as if you managed to shove the energy equivalent of all that mass in photons into the same area you would end up with the same black hole, according to general relativity.-RunningOnBrains^(talk) 10:38, 21 July 2011 (UTC)

Sea surface temperatures and earthquakes

Hi. This is not homework, nor am I trying to promote fringe theories, but rather I simply would like some feedback on the plausibility of this very informal hypothesis. Recently, I have made the observation that a few strong earthquakes in coastal temperature zones have been correlated with rapidly fluctuating sea surface temperatures (SSTs) days to weeks before the main earthquake. If this correlation does exist, then I hypothesized that the cause-effect relationship could have two possible mechanisms. One is that the changing SSTs actually contribute to the earthquake itself. For example, cold eastern boundary currents could become cut off by surface intrusions of anomalously warm water caused by various climate oscillations. The arrival of this water would pile toward the coast and warm SSTs downstream of the cut-off zone over the cold current, while the cooler water may sometimes arrive to suddenly reduce the warmth at the coast. Given the presence of an oceanic trench, this rapid warming and cooling may continue kilometres below the surface, shifting upwelling patterns and causing expansion and contraction, resulting in large pressure and density changes near the geologic fault line. If this earthquake fault is already stressed, the additional pressure changes and possible related atmospheric pressure changes (from cyclonic storm systems that change air pressure and further affect SSTs) provide the trigger for a moderate to large earthquake.

The second of two suggested mechanisms involves the seismic elastic potential energy changes prior to the earthquake as the cause of the fluctuating SSTs. Ambient friction in the fault line zone and stress build up may release heat energy, which propagates along the fault line into the ocean floor, resulting in warming of SSTs near the coast. However, the ongoing natural upwelling and induced uplift of warm water eventually leads to naturally cold water resurfacing near the site, again cooling the area and resulting in rapid SST fluctuations. In this scenario, changes in daily SST maps give the appearance that the strength of the cold eastern boundary current itself is fluctuating due to intrusion of warm water, when in fact an underlying tectonic stress build-up is the cause. The flucations thus signal, rather than cause, an earthquake.

So, I'd like to know whether either of these two mechanisms are at all plausible for large earthquakes. Also, please point me to any existing articles relevant to this subject (ones not related to earthquake prediction). Given that both are plausible, which one is a more likely explanation, or could the two cause-effect mechanisms generate a positive feedback cycle that mutually amplify and lead to triggering the earthquake? What would likely be the practical use of such a theory for earthquake prediction applications, should such a mechanism or an analogous version be proven in the eventual future? What factors would be likely to increase the earthquake risk of such triggering or predictive mechanisms in the future? Thanks. ~AH1 ^(discuss!) 19:36, 20 July 2011 (UTC)

The implication of this BBC article is that rises in sea surface temperatures before earthquakes are an observed and possibly accepted phenomenon (seemingly that the fault creates the temperature and not the other way round). As to why this isn't to my knowledge being used, well, I assume there are other reasons surface temperature could rise. Grandiose (me, talk, contribs) 20:45, 20 July 2011 (UTC)

I definitely would not take that as accepted fact -- the article in Advances in Space Research by RP Singh et al, on which the BBC report is based, has been cited by hardly anybody except its author. To me this idea seems very implausible -- the amount of heat it would take to have a noticeable effect would be huge. Ultimately the data will rule, of course, but I would need to see a lot more data than the four cases Singh et al reported in order to believe this. Looie496 (talk) 21:43, 20 July 2011 (UTC)

I think this is likely a case of correlation not implying causation, since sea surface temperature fluctuations most commonly occur near western boundary currents, of which the Kuroshio Current off the coast of Japan (and coincidentally, in the region with the worst earthquakes in the world) is the strongest.

Also please believe me when I say that BBC (and news outlets in general) have a horrendous record when it comes to reporting on science. They will take any speculative paper out of context and draw their own conclusions about what the authors are trying to say, or, even worse, assume that one scientist represents the majority view. I can't even find the paper off of which the BBC is basing their article.-RunningOnBrains^(talk) 11:34, 21 July 2011 (UTC)

Cavity Magnetron

Could a cavity magnetron be done in reverse in a way so that the em waves would interact with the magnetic field and give electrons energy to jump from a cathode to an anode and would any resonant frequencies be involved? — Preceding unsigned comment added by 09:06, 20 July 2011 (UTC) Lufc88 (talk) 09:08, 20 July 2011 (UTC) LUFC88

I think yes. There would have to be a small current initially to provide electrons. The external electromagnetic field would need to be at the cavity resonant frequency. Cuddlyable3 (talk) 13:57, 20 July 2011 (UTC)

I've read some where that this is why metal articles should not be put into microwave ovens.(other than sparking). they can reflect the radiation back into the magnetron and if the placement is right the resonance can cause the jumping electrons to fry it.Staticd (talk) 04:56, 21 July 2011 (UTC)

Reseaching hypothyroidism

I know the Internet is not a doctor and we should see the licenced professionals (and that is all lined up and all). But still it's also useful to be an informed patient and a part of the diagnostic process.

Trying to help a "friend" who got a bad number for a TSH test and has been having about 6 months of head pain and confusion. If y'all can point to the best wiki articles (or external or wiki articles that have external) that would help me my friend.

Kinda looking for general info, but also not to get bowled over with too much info. I guess few thought threads:

• understanding the TSH and what it means if that is high and the others OK (it is some sort of feedback system).

• what damage has been done by living like that for a long time (no regrets, just good perspective).

• Is medicine really required or is it possible that taking out all bad things (booze, sweets) or adding more good things (iodine [which may have been low based on strange diet], exercise) will just allow the body to fix itself.

• What sensations to look for that show the problem has cleared.

Peace. TCO (reviews needed) 21:38, 20 July 2011 (UTC)

The Reference Desks are not permitted to give medical advice, and this is virtually the paradigm of the sort of question we cannot answer -- a request for information related to the treatment of a specific person. Looie496 (talk) 23:29, 20 July 2011 (UTC)

Yes, most of the specifics cannot be answered. Would it be safe to assume that you have carefully read through the articles on thyroid hormone, thyroid-stimulating hormone, and hypothyroidism? I'm sure that you will find plenty enough background information to be an informed patient, and each of those articles has a number of external links or articles. --- Medical geneticist (talk) 23:35, 20 July 2011 (UTC)

Our article on the tests is kind of a mess in terms of different tables and all. And the different tests themselves are complex. I did scan them and saw all kinds of stuff. I guess not getting enough iodine can make a cretin. Maybe there are intermediate aspects of that.

P.s. Gracias. For kind remarks. And a teensy bit of advice sneaking through the policy constraint.  :-)

P.s.s. I guess I will go surf over to Mayo clinic. My head is kinda squeezed and am working a reduced capacity. Like trying to read organic chemistry with someone squeeszing me. Not my normal ability to vex the dosc with engineer logic and demands for evidence based approach.  :-( 23:47, 20 July 2011 (UTC)

In general, medication such as levothyroxine is very important in treating hypothyroidism, but only your doctor can answer your questions about damage and the possibility of correcting it with diet alone. Your other questions are answered in the articles Medical Geneticist linked to above, and you should get familiar with them and everything else you can find on the condition before your doctor's appointment. You might even want to bring highlighted/underlined printouts so you can remember to ask what you have questions about. 99.2.148.119 (talk) 06:42, 21 July 2011 (UTC)

Some of your comments seem inconsistent - please make sure you're aware of the difference between TSH (thyroid stimulating hormone from the pituitary gland) and the thyroid hormone that is stimulated by it. I can think of some other explanations for the headaches besides "subclinical cretinism", which I don't know happens or not. I think you should really talk to an expert now and get some further testing done - don't just go guessing around. Wnt (talk) 15:09, 21 July 2011 (UTC)

I think I should be a bit more explicit here, without making any diagnoses (which I'm not qualified to do): You've told us that you have pain in your head, and confusion in your head, and you're producing abnormally low levels of a hormone from your pituitary gland, which is in your head. Are you sure your thyroid is what you need to worry about? Wnt (talk) 15:21, 21 July 2011 (UTC)

Megatsunami

Say if the canary of Island of La Palma does slip and trigger a tsunami. When part of it hit Ireland would it result in a megatsunami or a regular tsunami. --93.107.16.224 (talk) 23:12, 20 July 2011 (UTC)

It would be impossible to predict with reliability, before the event, what effect it would likely have on any one place. That being said, Megatsunami#Canary_Islands has some reading for you. --Jayron32 23:19, 20 July 2011 (UTC)

Also, the term megatsunami is quite vague. Some would argue that the 2004 Boxing Day tsunami was a megatsunami. There is really no strict limit on what a megatsunami would entail, just that it is "bigger than a normal tsunami" (whatever "normal" means). -RunningOnBrains^(talk) 11:39, 21 July 2011 (UTC)