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June 11

Does anyone provide solutions on solutions?

After reading up a bit on vodka sauce where ethanol is used, for lack of a better terms, in a Liquid–liquid extraction, I started to wonder about some of the other things I'm cooking with. Obviously non-polar compounds will be extracted by cooking in oil or fats in general, but the ethanol is a polar solvent that mixes well with water. This got me thinking about chemistry in general, and for purposes of enhancing or avoiding certain flavors (e.g. right now I'm making saltless tomato sauce that's coming out way too fruity) I'm wondering about timing of addition things like vinegar that change the pH and other chemical changes that would affect the extraction of flavors from onions/garlic/tomatoes/kumquats/etc... Is there a reference anywhere that answers some of these questions about flavor extractions in various food-grade solvents? 71.231.186.92 (talk) 01:39, 11 June 2013 (UTC)

The chemistry is sufficiently complex that making reliable predictions is difficult. Given the relatively low cost of a trial-and-error approach, I'd recommend that. I've come up with several recipes that way. Incidentally, regarding a salt-free tomato sauce, have you tried adding some capsaicin (hot peppers) ? StuRat (talk) 02:20, 11 June 2013 (UTC)

The most likely source is Nathan Myrhvold's Modernist Cuisine. But it ain't cheap. Looie496 (talk) 04:41, 11 June 2013 (UTC)

I believe these topics are addressed in On Food and Cooking, which generally has a nice balance of chemistry, history, and culinary lore. SemanticMantis (talk) 15:26, 11 June 2013 (UTC)

Our Molecular gastronomy article also cites several useful sources. Roger (Dodger67) (talk) 07:23, 14 June 2013 (UTC)

Is that cold or just the feeling of cold that brings thermogenesis ?

I have learned that the feeling of cold and heat is produced by the activation of certain peripheral "temperature" receptors. the question is. if a person got a knockout for the genes for these receptors and he feels neither cold or heat, and sometimes in his life, dives in an arctic water lake (for example), will this person have thermogenesis while in water?. my intuition says he won't have because there will be no signal to start all of this metabolic state. (i just haven't learned yet if a man could survive birth without temperature receptors). i am eager for your answers ! thanks Ben-Natan (talk) 02:54, 11 June 2013 (UTC)

As our article on thermoregulation states (very briefly), thermogenesis is driven by a small brain area called the preoptic nucleus of the hypothalamus, which contains cells that are exquisitely sensitive to core temperature. That area also receives input from temperature sensors on the body surface, but core temperature is much more important. So a knockout of skin sensors probably wouldn't greatly impact thermoregulation. No doubt there are other kinds of knockout that do, but I don't know anything about them. As far as I can tell, the molecular mechanism of thermosensation in the hypothalamus has not yet been established. Looie496 (talk) 03:21, 11 June 2013 (UTC)

Sensation of cold is mediated by TRPM8, and heat TRPV3 (there are others for each, though). The OMIM entry for TRPM8 doesn't mention body temperature changes, [1] and the OMIM entries for body temperature are other genes. [2] Logically there is just too much disconnect between when you feel cold (just rushed outside, say) and when you actually have a low body temperature; there needs to be some space between these mechanisms. Wnt (talk) 03:34, 11 June 2013 (UTC)

Ways to turn a hurricane?

Could any of these things possibly turn a hurricane? (Weather modification gives a good overview of some ideas to stop one, but from the narrow U.S. context, it is not actually necessary - in many cases it would be desirable simply to give the storm a shove somehow to make it turn a hundred miles sooner toward the northeast)

• Do cloud seeding in winds leading toward one side of the hurricane to make them drop some rain in advance. Since the condensation of moisture provides heat, could this put an asymmetric force on the storm?
• Release some kind of thickening agent into the storm with drones to increase the viscosity of the water and change the droplet size, and so hopefully the rate at which the water condenses, with the same effect?
• Fire lightning rockets up through one part of the hurricane to change the charge distribution with the notion of altering how minute droplets of water repel one another due to charge on them, with the same effect?
• Anchor some sort of kites designed to create turbulent air flow (I'm thinking a density very roughly around 1 per acre) with the notion that under some specific condition as the wind rises, the turbulence will propagate from each kite over a long distance, changing the amount of resistance the wind experiences against the sea? (No, I haven't modelled this in a wind tunnel! my subjective recollection is that there are specific circumstances for some objects where a little protrusion on a model can leave a long trail of disruption behind it, but I could be so wrong about this optimistic scenario ;) ...)
• Put some sort of biodegradable oil on the water (as the article mentions) but not at the center of the storm, rather at its distant extreme to change the wind resistance (can oil do that?)

Last but not least, does anyone ever actually go out and try to fool with a hurricane's path, with any technology of any kind? Wnt (talk) 05:50, 11 June 2013 (UTC)

Check this out. --Jayron32 06:06, 11 June 2013 (UTC)

Have you looked at the article on tropical cyclone track forecasting? The factors that are used to forecast a storm track are basically the things you would have to change in order to alter one. The most important ones are probably uncontrollable, but you might conceivably be able to exploit the Fujiwhara effect or something. Looie496 (talk) 06:12, 11 June 2013 (UTC)

There is some kind of gel which absorbs many times it's own weight in water, and the drops then dissolve in saltwater. A fleet of cargo planes working non-stop could conceivably drop enough of it into a hurricane to affect it. This would cost millions of dollars, but could possibly save billions in damage. Another option is to prevent the water from getting hot enough to spawn hurricanes, by placing reflective floating surfaces on it. Not sure if this would be practical, though, and there's the environmental impact when all this material eventually washes up on shores. StuRat (talk) 06:40, 11 June 2013 (UTC)

. --Jayron32 13:40, 11 June 2013 (UTC)

[3]. That says it only absorbs 20X the weight of the gel, but that seems much lower than I recall. Even a sponge absorbs that much, right ? StuRat (talk) 15:47, 11 June 2013 (UTC)

FYI: The water contained within a hurricane weighs about 240 million tons [4]. So if your gel absorbs 20x it's own weight, you're going to need 12 Million tons of gel (assuming you don't waste any by dumping too much of it in one place or missing the target or whatever). A Lockheed Martin C-130J transport plane can carry about 22 tons (See this). So we're going to need around a half million air transport missions to mop up the entire hurricane. The C-130 costs around $10,000 per hour to fly[5]...let's suppose it's a 4 hour mission - then the cost of doing this is about 20 billion dollars...plus the cost of the gel. That's actually cost-effective for Katrina-scale hurricanes that cost in the 100 billion dollar range - but not for a "typical" hurricane that does just a few billion in damage. It's plausible on cost benefits - but definitely not a slam-dunk.

But the problem is that we don't have a half a million aircraft - the US owns about 200 of these large cargo planes (See this) - and that would mean doing 2,500 flights each - if they take 4 hours plus an hour turn-around time, then it would take close to two years of non-stop work with the entire US airforce, navy and army C130 fleets to soak up just one hurricane! To put a stop to all of the atlantic hurricanes would require every man, woman and child in the US to become a C130 crewmember or support person! (Not to mention the gel-manufacturing nightmare!)

Obviously you wouldn't need to soak up the entire hurricane to put a stop to it - but even if you only had to soak up 10% of it - it's still wildly impractical.

Summary: Silly idea! Won't work. SteveBaker (talk) 16:46, 11 June 2013 (UTC)

As I said, I think it's much more than 20 times. Also, if you can attack the hurricane during formation, say by wiping out the eye wall whenever it tries to form, you might be able to keep it from organizing and keep it as only a tropical depression, with much less of an effort. And, yes, if we decided to do this, we'd need to build a large fleet of planes just for this purpose. Due to global warming, and the expectation of more devastating hurricanes, such an option may be more practical as time goes by. This might also be a good application of unmanned airplanes, as taking off, flying to a specific target, dropping the load, and then returning to base isn't beyond the capabilities of modern technology. If we mass produced such planes, hopefully the cost per hour to run them would go down dramatically. StuRat (talk) 04:48, 13 June 2013 (UTC)

The large practical problem here is that hurricane prediction is not an exact science. Your efforts to divert the hurricane would be far from exact too. Now, consider what happens if you divert a hurricane and cause it to hit a major city instead of missing it - 1800 people die and 100 billion dollars go down the toilet and it's all your fault! As with anything like this where you try to use a small force to create a large change, you have to apply that force as early as you can...but the problem is that's when storm prediction is least able to predict the path accurately. Even just three or four days before landfall, the best math models we have were predicting that Katrina would hit the Florida panhandle. So clearly, attempting to change the path even just a few days before landfall is as likely to cause a problem as to solve one. Leaving it until you're certain that you won't make matters worse is leaving it too late to have a measurable effect. Improving prediction times is tremendously difficult - even in principle - because the system is highly chaotic (in the chaos theory sense). SteveBaker (talk) 17:05, 11 June 2013 (UTC)

There's no harm thinking big, but practicality tends to intervene. Will Rogers posed what he claimed to be a great solution to the German U-Boat problem in WWI: "Boil the ocean!" Leaving the details up to the experts, of course. ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:01, 11 June 2013 (UTC)

For what it's worth - in the last few years, there have been several special sessions at American Geophysical Union's annual meeting on the topic of geoengineering - that is, the task of working out the practical engineering considerations for earth-scale projects to intentionally affect climate and weather. It's already well-established that human activity does affect weather and climate. So, the task going forward is to design and engineer human activity to affect weather and climate in a controlled way. Serious scientists are expending serious thought on this issue - but it's still far from reality in the short term. Here's AGU's official position statement on geoengineering: Geoengineering the Climate System (2009). Excerpts: "proactive strategies could reduce the risks of climate change... (including) geoengineering: deliberately manipulating physical, chemical, or biological aspects of the Earth system"... Nimur (talk) 22:57, 11 June 2013 (UTC)

Hmmm - good detective work - thanks! Clearly this is nonsense. It can't possibly work...on cost grounds, on practicality grounds, on risk of doing more harm than good grounds...there are a million reasons why you can't do that.

The work by the American Geophysical Union isn't about attacking a single hurricane - it's about changing our society in ways that'll reduce our impact on global climate change - and some "Plan B" approaches to applying a bandaid to the problem if (as seems likely) we fail to do that. Things like injecting water vapor into the upper atmosphere to increase our planet's albedo. These are horribly dangerous things to consider doing - and it's unlikely that we could get international agreement to do that. But dialling down the surface temperature of the mid-atlantic ocean would reduce the amount of energy available for hurricane formation - which in turn would reduce the number and severity of hurricanes. Sure - that'll work - but it's not specifically a "fix" for hurricanes - it's a side-effect of a more general effort to engineer our impact on the planet. SteveBaker (talk) 13:55, 12 June 2013 (UTC)

I've tried to hold off responding because I've observed the OP editing a question is the kiss of death for getting more answers (hope this will be an exception!), but I should note that our article weather modification specifically mentions Dyn-O-Gel, claiming 1500x absorption, and if people are confident to debunk this at this point, please do. Myself, above, I didn't actually want to absorb the water, just change how droplets accrete or coalesce in some measurable way to affect how much heat of fusion enters a part of the storm; admittedly I doubt you can do that but I just don't know for sure. Of course, I admit that turning a hurricane in the Caribbean would be pretty useless - I'm thinking of the east coast U.S. in particular, where hurricanes often turn away and if they do they harm nobody but perhaps a few fishermen off Newfoundland. Wnt (talk) 16:11, 12 June 2013 (UTC)

...which is an excellent example showing that while some Wikipedia articles are excellent, some are crap. The reference cited in the article for Dyn-O-Gell is is a broken link. However the article is available on a paranormal/ghosts website at http://tech.dir.groups.yahoo.com/group/ParanormalGhostSociety/message/30659?var=1. Read it - you'll see it's rubbish. If that's not enough, it says the gell is made by the Dyn-O-Mat company. There is a domain name, dynomat.com registered but is inactive, and I could not find any evidence that the company exists. Note that Dynamat is a legit active company selling sound absorbent materials for automotive use. The History page for the Wikipedia article shaows that the Dyn-O-Gell bit was added on 7 April 2007 by editor Beland, apparently based on the paranormal/ghosts website (hard to tell for sure as the link Beland provided is not valid). The story was therein attributed to the Scripps Howard news service. You can search for old news reports on their website. There is no such story held by them. The story is just a load of rot, as I said before.

I just looked at this quickly and "Dyn-O-Storm" pulled up Discover Magazine saying the stuff is a polyacrylic acid derivative (sodium polyacrylate?) (I went off half-cocked a minute ago about polyacrylamide, but that's not the precise compound here) Wnt (talk) 06:28, 13 June 2013 (UTC)

I should say I like StuRat's notion of the floating mirror - in theory, if you had just the right material, you could spray a layer of highly reflective material that is just a few atoms thick, like a solar sail or something - I'd think you could do it with nanotech, but I bet some simpler but smarter engineering could make it able to self-organize and reorganize due to chemical properties, yet be ultimately biodegradable. It would be nice if it made use of iron so you could fertilize the ocean with the same intervention, thereby taking on the issue both long-term and short-term. :) Wnt (talk) 16:11, 12 June 2013 (UTC)

Dyn-O-Gel has been dismissed by the NOAA as ineffective. See the updated article for link. 86.121.18.17 (talk) 23:28, 13 June 2013 (UTC)

This looks persuasive [6] - nonetheless, I have to note it sounds like the simulation addressed only overall wind speed. Perhaps my naive assumption that it should be easier to nudge a hurricane than disrupt it is actually wrong though, and that's why they didn't test it? Wnt (talk) 03:18, 14 June 2013 (UTC)

Yes, that 2000-to-1 ratio is closer to what I remember. One thing this study doesn't address, though, is that they are only looking at a fully developed hurricane. I'd think it would be far more efficient to attack it when first forming. Of course, to do this, we need better prediction models so we know which tropical storms will develop into deadly hurricanes, so we can concentrate on just those. StuRat (talk) 20:33, 14 June 2013 (UTC)

Chemistry and relativistic effects

I often hear the concept thrown into speculation in research reports, but have no idea what it actually means in a particular context. Here is an example: Unlike the lighter congeners, zinc(II), and cadmium(II) hydride, solid mercury(II) hydride is a molecular solid instead of a network solid. Apparently, it comes down to relativistic effects. What are those effects in this context, and how do those effects affect? Plasmic Physics (talk) 11:03, 11 June 2013 (UTC)

Electrons are not going to travel faster than the speed of light in an atom. For high charged nuclei the electrons will be travelling very fast near the nucleus, and would have greater effect for D or F orbitals. However this effect also can modify hydrogen atom spectra, causing splits in lines from higher shells. The result for the heavy elements is that they are softer and melt cooler. One effect is that the electrons are effectively heavier, and then moving slower, and reduce the Bohr radius, so densities are higher. Read Relativistic quantum chemistry for the article on this here. This explains that the 6S orbital in mercury is shrunken so that its bonds are weak. Graeme Bartlett (talk) 12:18, 11 June 2013 (UTC)

OK, thanks. Can you also please explain why mercury(I) chloride is Hg
₂Cl
₂, whereas mercury(I) hydride is just HgH? Plasmic Physics (talk) 14:06, 11 June 2013 (UTC)

You wrote that HgH was stable up to about 6K in matrix isolation. This gives a clue that the bond is extremely weak. Stable in isolation means that two molecules react with themselves. You can guess that the Hg₂H₂ is even more unstable and breaks apart to H₂ and Hg. Even if this Hg₂H₂ was stable enough in isolation it would be extra hard to make it in isolation as you need to get 4 atoms together in one place without extra reactive atoms. The bond in H₂ is much stronger than in HgH. What is your reference for dihydrido-1κH,2κH-dimercury existing? Graeme Bartlett (talk) 21:20, 11 June 2013 (UTC)

It's from the same paper by Andrews, and in a 2005 paper by Alireza Shayesteh (I think). From what I remember, the calculated enthalpy of formation for Hg
₂H
₂ for higher than for HgH, coupled with a low activation energy for the conversion to individual HgH. I don't remember about the energetics for total decomposition of Hg
₂H
₂ to the elements. It requires only a quarter of the energy to break the second bond of HgH
₂, than it does the first, and the first requires approximately two fifths of the energy to break on H-H bond. Plasmic Physics (talk) 22:30, 11 June 2013 (UTC)

Dissociation and eutectics

What is the eutectic point of a NO₂/N₂O₄ mixture? Is it even possible to liquefy such a mixture fast enough, before equilibrium is restored? Plasmic Physics (talk) 11:18, 11 June 2013 (UTC)

A related question: is it in theory possible to speed heat octosulfur to estimate it's boiling point? That is, heating it fast enough such that decomposition does not have significant blurring effect. Plasmic Physics (talk) 14:10, 11 June 2013 (UTC)

What if you heated octasulfur at a reduced pressure? That's pretty common for lots of things that can't be boiled at atmospheric pressure (because it's just too high-T to be convenient or because it thermally decomposes), either for measuring/reporting bp or simply for purification. There are heuristics for converting to other pressures, or it can simply be reported at whatever mmHg was used. DMacks (talk) 18:04, 11 June 2013 (UTC)

I suppose I could, but my question is concerned specifically with standard pressure. Monitoring the temperature differential of the substance over time, and looking for a step in such a plot. Plasmic Physics (talk) 23:08, 11 June 2013 (UTC)

Air oxidation of Ammonium iron(II) sulfate

Quoted from Ammonium iron(II) sulfate

In analytical chemistry, this salt is preferred over other salts of ferrous sulphate for titration purposes as it is much less prone to oxidation by air to iron(III). The oxidation of solutions of iron(II) is very pH dependent, occurring much more readily at low pH. The ammonium ions make solutions of Mohr's salt slightly acidic, which slows this oxidation process. [1]

So oxidation occurs readily at low pH. Ammonium ions make it acidic reducing the pH, which should make the oxidation happen much more readily. So how come is it slowing down? This is a contradiction.

What's correct?

--Gauravjuvekar (talk) 16:25, 11 June 2013 (UTC)

EDIT: Ammonium iron(III) sulfate says that it's abbrevated to FAS. Is FAS really Ammonium iron(III) sulfate(ferric) or ammonium iron(II) sulfate(ferrous)

--Gauravjuvekar (talk) 16:57, 11 June 2013 (UTC)

Low pH slows oxidation, so I have changed the article. Sulfuric acid is often added to solutions to stop them oxidising. Looking around for FAS it is used for Ammonium iron(II) sulfate more than for the ferric ammonium sulfate. [7] (232 hits) and [8] (54 hits). I would suggest that you don't use FAS alone as an abbreviation for this! Graeme Bartlett (talk) 21:57, 13 June 2013 (UTC)

Voltmeter and ammeter

Why do we combine voltmeter in parallel combination and ammeter in series combination? 106.209.208.31 (talk) 16:34, 11 June 2013 (UTC)

To answer simply: voltage is the same across parallel elements, but current is the same through elements in series. And vice versa: voltage differs across elements in series (except in the case when the impedances are identical) and current differs through parallel elements (except in the case when the impedances are identical). So if you connected the meter the wrong way, you wouldn't be measuring the thing you want to measure (not to mention any possible danger to your equipment and self)! You can make a deeper answer with regard to Maxwell's equations, but I assume you don't want that (not that I could give such an answer anyway). --Atethnekos (Discussion, Contributions) 16:58, 11 June 2013 (UTC)

Another way of thinking about it is to ask "what is voltage" and "what is current"? Voltage is a difference between two points, so you put your two meter probes on those two points to compare them. Current is flow, so you put your meter so that the electricity flows through it to measure that rate. DMacks (talk) 18:00, 11 June 2013 (UTC)

The hydraulic analogy is always useful in these cases. Voltage is like pressure in a system of water pipes - current is like the flow rate. If you need to measure pressure between two points you need to place your pressure gauge between those two points (although one point might be the ambient air pressure) - but for flow rate, you need to insert the flow meter into the pipe to measure how much water flows through it every second. SteveBaker (talk) 19:18, 12 June 2013 (UTC)

Voltmeters have very large internal resistances (so they must operate to full-scale deflection with very small currents). If we place a voltmeter in series with the electromotive force, the resistance of the voltmeter would only allow a very small current to flow and the circuit would most likely not operate as intended. So voltmeters are usually placed in parallel with a major circuit element, the one whose voltage we want to monitor. Ammeters have very low internal resistances. If we place an ammeter in parallel with a major circuit element, most of the current supplied by the electromotive force will flow through the ammeter rather than the major circuit element, so the major circuit element won't operate as intended. We usually want to monitor the magnitude of the current flowing through the major circuit element, not interfere with that current, so we connect the ammeter in series with it. See also Kirchhoff's circuit laws. Dolphin (t) 08:17, 14 June 2013 (UTC)

Are vaccines homeopathic?

I mean mainstream vaccines and in the sense that you are using the same (homeo) substance as the illness (pathic). OsmanRF34 (talk) 23:58, 11 June 2013 (UTC)

No. Homeopathy is quackery designed to bilk money out of gullible people. Vaccines are proven to work. Big difference. Of course, if you read both articles, you'd already know that. If you're trying to work from the word "homeopathy" to make some connection, you'll also want to read etymological fallacy which explains nicely where you're going wrong there as well. --Jayron32 00:03, 12 June 2013 (UTC)

I do not dispute that what we buy as homeopathic is quackery or that vaccines work. But ignoring the etymological connection, and starting with the idea of "using the same substance as the illness to treat the illness", what's wrong with saying that it works, but only preventively, like a vaccine. OsmanRF34 (talk) 00:11, 12 June 2013 (UTC)

Homoeopathy doesn't use 'the same substance' - it uses water. Any 'substance' is diluted to the extent that you are highly unlikely to get a single molecule of it in the 'remedy' AndyTheGrump (talk) 00:23, 12 June 2013 (UTC)

Because the comparison is contrived and misleading. Vaccines have nothing to do with homeopathy whatsoever. The error you are making is a category error with the help of an eqivocating over-simplification. Saying that vaccines and homeopathy are similar because they "use the same substance as the illness to treat the illness" is like saying the planet Mars is like Stalin because they are both "red". Dominus Vobisdu (talk) 00:28, 12 June 2013 (UTC)

It's slightly completely opposite in approach and intent. To oversimplify each, one tries to induce a very mild case of the disease to prime the body to strongly fight the real one in the future. The other uses an unrelated agent that induces similar symptoms as a disease does to cure the disease in someone who is already sick. The commonality--"agent that can cause the symptoms"--is, as Dominus Vobisdu says, doesn't make them intrinsically related in any other way. DMacks (talk) 00:58, 12 June 2013 (UTC)

Also, the dilutions involved in homeopathy are such that not one single molecule of the "active ingredient" is actually present in the "treatment". That's emphatically not the case for a vaccine. You may get millions of weakened or killed viruses in a flu vaccine shot but not one single molecule of raw duck liver (yes, really!) in a homeopathic flu "treatment". Homeopathists would not regard a flu vaccination as a homeopathic dose. Conflating these two approaches can only lead to "Very Bad Things" happening! SteveBaker (talk) 13:42, 12 June 2013 (UTC)

The problem here is that "homeopathy" refers to two different things: the deceptive practices of Hahnemann and his ilk, and the much older vague principle of "similia similibus curantur" held by Paracelsus and other medieval physicians. [9] The concept of homeopathy as one of the ancient philosophies of medicine is legitimate though highly unreliable (as the Lancet mentions with the business of treating wounds with boiling oil). Vaccination can fairly be seen as an extension of that principle. Heuristically, it may still be a valid source of blue-sky inspiration, though I should emphasize that in biology there are no two things more similar than something's synonym and its antonym, and so homeopathy and allopathy, in the philosophical sense, are very closely related. (I know that is hard to wrap your head around, but by and large, to inhibit a biological process you need something that is almost but not quite the same as something that activates it!)

To comment on the social context, medicine is a racket but it has many mostly honest practitioners: the regulatory privileges held by its schools make them extremely valuable economically. Some, like allopaths, have managed to hold onto a high reputation, others, like osteopaths, seem to have a harder time holding on - and then there are the homeopaths, who have the same legal monopoly of "prescription" over their formulae of highly diluted water as the more common physicians hold over drugs that are actually needed. It is not impossible that one of the other schools could have been infiltrated and debased in the same way, but allopathy, with its tendency to provide quick obvious relief of symptoms, would have been harder to replace with water. Wnt (talk) 15:55, 12 June 2013 (UTC)

It should be noted that Wnt holds an idiosyncratic and unsupported view of mainstream medicine, and his unreferenced opinions should be taken with the largest grain of salt you can muster. --Jayron32 17:18, 12 June 2013 (UTC)

http://giantcrystals.strahlen.org/europe/merkers3.jpg

• Vaccination works for reasons that are easily understood, verified, tested and reproducible. Repeated, detailed studies show that most vaccines work very well in reducing the chance of their targetted disease occurring. Homeopathy (in all modern senses of the word) doesn't actually work at all (there is not one scientific study that demonstrates anything more than a placebo effect), and the means by which it's claimed to work are vague, contradicted by different practitioners and entirely unscientific.
• Allopathy also works fairly well in most cases - and usually (but not always) we understand why it works - and we're always careful to test it and measure things like side-effects. If you have a severe anaphylaxis attack, a shot of epinephrine will likely fix you right up. That's not a coincidence or a piece of luck - it's because we know that epinephrine is a vasoconstrictor. All of this is demonstrable in a scientific fashion - from the cause, to the cure to the reasons the cure works, the possible side-effects, the future prognosis, etc.
• All that the homeopathists can say is something about water being imprinted with the memory of something you added to it and then diluted to nothingness...they don't say why it works, they don't test to see if it actually does work, the whole thing is entirely made up of guesswork from people who are largely without any science training whatever.
• Osteopathy falls somewhere between the two. There have been a few studies that seem to show that it works better than placebo - but it's very hard to come up with a convincing placebo to compare it to - so that's a somewhat dubious claim - and there is little scientific explanation for how it works (if indeed it actually does). Discussing osteopathy is tricky because the term means radically different things in different countries. In the USA an osteopath does similar training to a conventional doctor - but in other places they may be regulated entirely differently - or not regulated at all - so the resulting mess makes it unlikely that the osteopathic treatment you get in those places is going to be any use anyway.

SteveBaker (talk) 19:10, 12 June 2013 (UTC)

I basically agree with all that, but I don't think any of it contradicts Wnt's assertion that "medicine is a racket but it has many mostly honest practitioners". It's a racket with a solid scientific basis, yes, but that doesn't keep it from being a conspiracy in restraint of trade, which indeed it is, and in that sense it's a "racket". --Trovatore (talk) 21:38, 12 June 2013 (UTC)

Is there a solid scientific basis for having prescription homeopathic medicines, which cannot legally be dispensed by ordinary people? Once you answer that: is there a solid scientific basis for having prescription regular medicines? For example, suppose that someone has high blood pressure and takes a drug daily to keep the dose low. He doesn't have money for a doctor that month, and by policy he can only receive so many refills for any medicine. Has someone done a scientific study that shows that it is safer for him to go off the high blood pressure medicine cold turkey than to be allowed to purchase a refill at his own risk based on his own personal decision making? Would an IRB even say it was ethical to conduct such a study? No. Profit comes first, and it really is that simple. Wnt (talk) 21:51, 12 June 2013 (UTC)

I meant there is a scientific basis for the treatments, not for the public policy. --Trovatore (talk) 22:21, 12 June 2013 (UTC)

@Wnt: There is no reason to have prescription-only homeopathic treatments. They are either water, alcohol and water, sugar pills or other placebo-like substances. Since they have no effect whatever on the body (which is why they don't work), you can't overdose on them - so they don't need to be prescription-only - and as far as I know they aren't. On the other hand most prescription medicines have potentially dangerous side-effects and have to be administered in carefully considered dosages (eg, the safe dosage may depend on your body weight, gender, age or life-style - it may be necessary to limit the duration of treatment to avoid addiction - or to encourage completion of a course of drugs in order to avoid drug-resistant diseases - or to avoid drug interactions). For those reasons, it's considered necessary to involve an expert (a doctor, for example) who can determine whether the risks and consequences of the side effects exceed the risk of not treating the condition - and who can determine an appropriate dosage. Limiting the ability to purchase such substances is considered a matter of public safety.

The issue of funding of conventional medicine is an entirely political/financial matter - not a matter on which science can reasonably rule. Your comment presumably comes from the perspective of a person living under a political system that values low taxation over universal health care. If you lived (for example) in Brunei (health-care costs a flat rate of about 80 US cents per consultation with no additional charges for drugs, hospitalization, surgery, etc) - your perspective on the nature of conventional medicine would undoubtedly be different. SteveBaker (talk) 02:45, 13 June 2013 (UTC)

I don't think the point is about funding. The point is about monopolistic practices. --Trovatore (talk) 04:04, 13 June 2013 (UTC)

What monopolistic practices? There are dozens of doctors and at least a couple of hospitals to choose from in every modern town or city - and once a drug comes out of patent protection, there are usually multiple manufacturers who compete on price to provide generics - there are even competing stores selling those drugs, who also compete vigorously on price. Sure, the drug company has a monopoly on the drug initially - but that's an issue of patent law, not the way that medicine works. You could certainly patent a homeopathic treatment if it actually worked - the manufacturers don't because patent battles between them would rapidly reveal that they're selling you bottles of water for $14 a pop - and bottles of water are not patentable. Besides, cutting the requirement to have a prescription out of the system wouldn't result in any more choice than you have now. SteveBaker (talk) 13:17, 13 June 2013 (UTC)

The AMA controls licensing and thereby restricts the supply of practitioners. Over the years, they have gotten rid of the general practitioner position (who didn't have to do a residency), and as I understand it are moving to restrict the supply of new nurse practitioners (allowed to prescribe) by making them get a doctorate. Obviously these measures reduce downwards pressure on pricing that the market would otherwise supply, especially if there were some sort of price transparency, and if tax incentives were not such that most routine medical care is provided through insurance (not what insurance is for!) so that the customer doesn't usually even know what the price is.

You may think that the measures that restrict supply also elevate quality, and who knows, perhaps they do. In a normal market situation, consumers are allowed to weigh such a purported benefit against the cost. --Trovatore (talk) 16:39, 13 June 2013 (UTC)

In a very limited sense, there are widely reported monopolistic-shenanigans by drug companies, up to and including use of the patent system to extend government patent protection (which is a form of endorsed monopoly that has its benefits to a point, so I'm not condemning the entire system),[10], [11], shady or too-cozy relationships with those that will prescribe the medication (over cheaper and often more effective medications), etc.[12] and [13], [14]. This sort of stuff isn't the tin-foil-hat crazy conspiracy stuff that Wnt seems to be on about when he condemns all doctors, and it shows up in mainstream media and well-respected scholarly studies all over the place. That being said, it is important to place the problems in the pharmaceutical industry into context, and it is still not reasonable to extend the well-documented shenanigans there with condemning doctors, nurses, midwives, PAs, and other front-line medical professionals who provide important, effective, and necessary care to the ailing. Doctors by-and-large are doing excellent work, and objections to the entire medical industry based on how some Big Pharma companies behave is unfounded. --Jayron32 13:56, 13 June 2013 (UTC)

Tinfoil hat conspiracy theory? I'm so relieved to hear that pharmacies really will refill a high blood pressure medicine prescription as a matter of compassion or respect if the person being treated can't afford to make a mandatory visit to the doctor two or three times a year - I must have been reading some of those wild internet conspiracy sites to think otherwise. Doubtless the marketing strategy for Oxycontin, the monopolization of Colcrys, the fads for hysterectomies and tonsillectomies and wisdom tooth extraction, and indeed, the marketing budget of pharmaceutical companies (and thus pretty near their entire budget) are all popular delusions without basis in fact. If not, do tell me what conspiracy theory you have in mind that I should recant? Wnt (talk) 16:26, 13 June 2013 (UTC)

I understand your frustration - but it's not a problem that's inherent to allopathy - it's simply a function of the cost of healthcare where you happen to live. That's a political/economic matter - not a medical one.

Pharmacies won't refill a prescription because the law doesn't allow them to - it's not a lack of compassion.

In your example, high blood pressure medications of all kinds can be quite dangerous. Just look at the most common hypertension treatments and their contraindications: Thiazide#Contraindications or ACE_inhibitor#Contraindications_and_precautions, Beta_blocker#Adverse_effects, Calcium_channel_blocker#Toxicity, Angiotensin_II_receptor_antagonist#Adverse_effects and so forth. Not one of the available treatments for hypertension is without side effects and absolutely all of them have rather detailed contraindications that entail understanding other conditions that the patient may have developed since starting the course of treatment and other drugs that they might be taking. It does make sense to require periodic checkups before continuing with the same treatment. If someone were allowed (for example) to buy their own Thiazide (a diuretic that's often prescribed for hypertension) - then they might well continue to take it long after they need it - and after starting to develop some other condition such as diabetes - or after giving birth to a child who would suffer greatly from the Thiazide getting into breast milk. It takes a trained professional to re-examine the patient sufficiently frequently to be sure that this drug (which is really very cheap and quite effective) is still safe and necessary for this particular patient. Look at Angiotensins - they have a list of 13 known side-effects. Do you know them all - and which ones are sufficiently serious to require an alternative treatment or sufficiently mild that they are less serious than the hypertension that's being treated? How do you know whether the thiazine that's helping your blood pressure isn't causing hypokalemia or seriously worsening a case of diabetes that you didn't know you'd developed? It's essential that patients who are taking those drugs are examined for their side effects and removed from treatment when their condition is sufficiently alleviated - or switched to an alternative treatment when the one they have been taking becomes problematic. The idea that once a drug has been prescribed, it may be taken indefinitely without serious consequences is dangerous nonsense...and that's why the law requires a periodic re-examination in situations where a drug is not considered safe enough for over-the-counter sales. SteveBaker (talk) 13:45, 14 June 2013 (UTC)

Sure, there are dangers; there are also dangers for a patient stopping cold turkey. What decides which dangers are the worry? The one that would cut into somebody's profits. I am actually quite confident that Wal-Mart could put together a set of pamphlets and a computer kiosk in a couple of months that could guide patients through all the side effects of those drugs with reliability not much different from the doctors, who never really monitor every possible risk anyway. (and that, if allowed, their pharmacy people could handle any blood collection for tests as readily as they handle a vaccine injection) Wnt (talk) 04:09, 15 June 2013 (UTC)

Words don't always have the same meaning as you would guess from the literally meaning of their roots.

In modern English, Homeopathy refers to a pretty specific (discredited) branch of medicine.

The underlying philosophy of Homeopathy and vaccines have the superficial similarity you mention, but I think in general vaccines are more closely analogous to the age-old concept of building up a resistance to poison, but even that shouldn't be taken as more than a loose metaphor.

(Sometimes "Homeopathy" is used (by advertisers) to mean all unproven herbal remedies, But that's not an accurate use of the word, and it has nothing to do with the word's roots.)APL (talk) 23:51, 12 June 2013 (UTC)

Although this doesn't really answer the original question, I think it's worth at the very least noting that not all homeopathic remedies are completely devoid of the alleged active ingredient, or source of memory, or whatever you want to call it. Some homeopathic preparations are not diluted to the point that the ingredient no longer exists. Others, through a combination of insolubility/immiscibility of the active ingredient and stupidly designed means of dilution, still contain active ingredient when they should not. This does not change the fact that homeopathy still has literally no basis is any valid science.

But then back to the question, I'll agree with most of the above that the similarities are superficial. They both began with the assumption that sources of similar illness may treat or prevent the same. Even that similarity is fuzzy, since homeopathy was looking at any two things that caused similar symptoms, whereas vaccination is using an infectious agent to prevent disease from the exact same infectious agent (with the rare exception of things like cowpox/smallpox, where a reason to believe vaccination would work already existed). And that is where the similarities end, because development of a vaccine is always followed by rigorous scientific experiments to prove its validity and improve its application, whereas homeopathy functions purely as a means of separating fools from their money. Someguy1221 (talk) 04:17, 13 June 2013 (UTC)

Homeopathists don't even agree amongst themselves. I edited the Homeopathy article for a while - and practicing homeopathists would often come to the talk page to complain about how our article is so "biassed" against them(!). One of them told us that our article was failing to explain that higher dilution rates were reserved for treatments that had to target a very specific part of the body and lower dilution rates were used for treatments that affected the entire body. I tried to find a reference for that claim and found that while some homeopathists claim that, others claim the exact opposite and yet others claim that increasing the dilution just makes the treatment more powerful and made no claim of targeted treatment with higher dilutions. This is true throughout homeopathy - almost any statement that one of them might make is found to be contradicted by others. Because there is no scientific basis - or concerted efforts to test these ideas, there is nothing preventing homeopathists from making wildly divergent claims - and since many of the leading proponents make money by writing books - they can make more money by "discovering" new things about homeopathy and writing about them. This results in an ever increasing spiral of wilder and wilder claims as each person has to find something new to write about to keep the gravy train running. Since none of the claims produce any actual clinical results (beyond placebo at least) - then all claims are equally valid and there is no means to distinguish "correct" from "incorrect" statements.

It's pretty hilarious to question a committed homeopathist from a scientific perspective: "So you claim that dilution of some initial substance makes the treatment stronger. But even the best quality distilled water contains some contaminants - and no matter how careful you are during your preparation, there are guaranteed to be things like metal ions leaching into the water in the initial dilution stages. Don't those contaminants undergo yet more dilution and also gain potency?"...and..."How do you clean the containers that you use to do the dilution? Doesn't washing them out at the end just leave an even more potent treatment left in the container?"...it's like shooting fish in a barrel! They don't like answering questions like that. SteveBaker (talk) 13:17, 13 June 2013 (UTC)

June 12

Mites and ticks

Is it true that mites and ticks find it harder to bite/sting musclier people? Clover345 (talk) 00:53, 12 June 2013 (UTC)

Probably, in general. Men are generally more muscular, and generally have thicker skin. B^e——C_ritical 01:04, 12 June 2013 (UTC)

But muscle isn't attached to skin so why would it have an effect? Clover345 (talk) 01:44, 12 June 2013 (UTC)

"Probably, in general." Is about as unspecific as you can get two words to be. Men are generally more muscular, What has the musculature of men have to do with tick bites? Are women more prone to tick bites? and generally have thicker skin. Do they? is that a guess too? I could almost believe if you had said that men on average have thicker skin on the palms of their hands because men on average they do more manual labour, but even then I wouldn't be totally convinced. And what does thick skin have to do with musculature?? Not a single word of that reply helps answer this question in any way. Now, subcutaneous fat I could believe plays a factor, less body fat makes a person appear more muscular but it is not correlated. You can have skinny weak people with little body fat or you can have huge muscular people with very high fat, like sumo wrestlers, so I doubt actual musculature has anything to do with it. A thinner skin and fat layer might make it harder for a tick to bite you, but for all we know, without a reference, it might make it easier for a tick to bite you. Taking a stab in the dark without any logical induction does not help at all. Vespine (talk) 05:48, 12 June 2013 (UTC)

I think Becritical was probably trying to make a joke. There is a statistical correlation between muscularity and thick skin, so there is probably a statistical correlation between muscularity and tick-bitability. This is a prime example of the fact that correlation does not in general imply causation. Looie496 (talk) 06:37, 12 June 2013 (UTC)

:D B^e——C_ritical 13:56, 12 June 2013 (UTC)

A tick can bite through cowhide with no problem. Human skin is much softer so I doubt a tick would find it harder - even in muscular people. I've had tick bite fever several times and I would say, as a generalization, that ticks seem to prefer the softer skin on your body - e.g. inner thigh groin area, under arm area and scalp. This may have nothing to do with the softness of the skin but rather that they can more easily hide in these areas and suck away unnoticed. This is based purely on my personal experience.196.214.78.114 (talk) 07:28, 12 June 2013 (UTC)

There are many species of mites and ticks - perhaps there is some variability in their bite capability? Certainly there are ticks that feast on cows - and those must be able to penetrate the thick hide on those animals. However, these kinds of blood-feeding pests aren't always able to cross species (eg dog fleas don't like to bite humans)...so it's possible that the kinds of tick that can bite through cowhide simply don't have what it takes to feed on humans for other reasons.

We need some solid evidence here - a decent reference would definitely help in answering this question accurately. SteveBaker (talk) 13:37, 12 June 2013 (UTC)

Agreed - it's very important to get the original folklore right before you try to confirm it. I don't know for example if what they mean is that someone who is active is harder for a tick to hang onto, etc. Wnt (talk) 15:39, 12 June 2013 (UTC)

I'm having trouble finding any study of the bitability of different people. There are plenty of papers on tick preferences, but most concern species preference. One paper states that, at least in South Africa, few ticks actually prefer humans, mostly feeding on other, larger animals[15]. Put that in the pile of things that suggest our skin should not be a problem at all. The one study I could find on preferences between different people was concerning adults vs. children, and concluded that behavior (time spent near tick habitats) rather than size or odor was the main driver of bite-rate differences. I seem to have misplaced that paper, so please forgive the lack of citation. I also question the very premise that muscle mass would even be associated with skin thickness. In at least one part of the body, skin thickness seems to be more associated with fat than muscle [16], which has an accompanying curious correlation between skin thickness and prognosis for kidney failure patients! Just another reminder that Looie's point is very important. So in the end, I question every aspect of this question, even the underlying claim - if the main determinant of tick bites is behavior, I'd expect people doing outdoor athletics, who may be more muscular, to get more tick bites. And if none of this has anything to do with skin thickness, which was not suggested by the OP, then I question it nonetheless, as the ticks are not biting through to muscle anyway. Someguy1221 (talk) 04:34, 13 June 2013 (UTC)

Sievert

In the article Sievert there are outdated quality factors which are superseded by ICRP 103 publication. — Preceding unsigned comment added by 217.21.43.22 (talk) 09:18, 12 June 2013 (UTC)

Well... update it? — Preceding unsigned comment added by 217.158.236.14 (talk) 09:31, 12 June 2013 (UTC)

Indeed, we encourage anyone who has a solid reference for a fact (and the ICRP publication would certainly count) to dive in and edit the encyclopedia to make it better. If you feel nervous about doing that, then you should at least report your findings on the "Talk" page for that article: Talk:Sievert - because this really isn't the right forum for that kind of thing. SteveBaker (talk) 13:32, 12 June 2013 (UTC)

It was mentioned there a couple of times, but nobody cares. -- 217.21.43.222 (talk) 16:59, 12 June 2013 (UTC)

Somebody cares - but anybody who works with radiation safety - and requires both precision and currency - should not be consulting a free online encyclopedia. Our encyclopedia article provides a thorough summary, and enough information to help guide anyone with more interest towards proper reference material. In fact, ICRP Publication 103 is the first reference listed in the sievert article. It is available for purchase, and a free excerpt is available online. Nimur (talk) 18:00, 12 June 2013 (UTC)

Basic rocket anatomy

Looking at this picture of the recently-launched Chinese rocket, I was just wondering, what is the main big tube most likely filled with and what about the smaller tubes on the sides? I see a number of types of setups at Rocket propellant. If one of those, e.g., LOX and kerosene, are the case here, are each of the tubes likely independently having all needed to be a thruster, or are the small tubes and the one big one having fully different ingredients only all together forming a working thrust system? 20.137.2.50 (talk) 14:23, 12 June 2013 (UTC)

According to our Long March (rocket family) article "the main stages and associated liquid rocket boosters use dinitrogen tetroxide as the oxidizing agent and UDMH as the fuel". Each of the liquid rocket boosters will be a self-contained rocket system, linked to a central thrust control. Gandalf61 (talk) 14:45, 12 June 2013 (UTC)

Long March seems to have a very similar booster arrangement to the R7/Soyuz rocket family, for which there's more public documentation available. Starsem's outline guide to Soyuz (here) shows internal diagrams for the Soyuz core stage and for its four strap on boosters (p22-). As Gandalf61 says for the LM, the Soyuz boosters run (essentially) the same engines as the core stage, and all four boosters and the core have their own fuel and oxidiser tanks. For the Soyuz, calling the core stage "stage 2" is a bit misleading, as its engines are lit at takeoff and burn (at about 50% power) all the time the boosters are running. Once the boosters are finished and gone the core throttles up to 100%. In contrast, this page says that the LM's core doesn't start until shortly before the boosters are shed. -- Finlay McWalterჷTalk 17:16, 12 June 2013 (UTC)

Main Battle Tank

I have a question which may seems to be a silly question , when you take a look on the turret before assembling it on the hull , you find that it is impossible for the loader in a tank like leopard 2 to reach the ammo storage at the left of the driver because , there is an obstruction between the loader and the ammo storage because of the extension of the turret inside the hull (the cylinder which contains the crew) as in the image on this page http://www.miscellaneoushi.com/Military/army/army_tanks_german_bundeswehr_leopard_2_1280x853_wallpaper_25616 — Preceding unsigned comment added by Tank Designer (talk • contribs) 14:47, 12 June 2013 (UTC)

You should explain what you're asking better. Simply looking at the picture I don't see an obvious obstruction, and the idea that the person loading the shells can't reach the ammo seems highly unlikely. Wnt (talk) 15:37, 12 June 2013 (UTC)

Note also that, in principle, it is not necessary for the loader to be able to easily reach all of the tank's ammunition. Tank designers could easily opt to shoehorn in additional ammunition in inconvenient spaces, with the understanding that it can be transferred into battle-ready storage when the tank is not engaged. I believe, but can't cite specifics, that some tank designs have even incorporated such storage in external compartments that cannot be reached unless the crew exits the vehicle. This method of ammunition storage has been used in other areas, such as the WW2-era Type VII U-Boat. — Lomn 17:20, 12 June 2013 (UTC)

That extension doesn't appear solid - I don't see what obstruction you're referring to. There are a bunch of items inside that space - but it may well be that they are simply stowed there temporarily when the turret is removed (eg to make wiring harnesses easier or something). (Higher res version of that image is HERE). This image shows ammunition storage both behind the gunner in the turret and down in the front section of the hull. This article talks about how the ammo is reached and suggests that the rounds stored in the hull are the primary ones - with the additional rounds in the turret locked away behind an electrically operated door. SteveBaker (talk) 18:43, 12 June 2013 (UTC)

And while we're on the topic, why can't they devise a system for automatically loading shells, rather than requiring people to do it ? We've been able to do this with bullets since the Gatling gun (or earlier), after all. StuRat (talk) 04:30, 13 June 2013 (UTC)

See Autoloader, which are indeed used in many tanks. A common argument against autoloaders is that until recently, humans were actually about as fast as them anyway, for your typical tank-caliber guns. There were also concerns of the reliability of the autoloader, and the fact that incorporation of an autoloader into many existing tanks would require a dangerous relocation of the ammunition, such that accidental detonation of the ammo would be far more likely to kill everyone in the tank. That particular concern has been mitigated in many vehicles by more recent improvements to autoloader design, or by designing a new vehicle around an autoloading gun in a way that eliminates the problem. Someguy1221 (talk) 04:45, 13 June 2013 (UTC)

June 13

Non-circular replacement body joints

There's an ad on TV that shows people riding bicycles or driving cars, comically, with elliptical wheels, then the announcer says "Our replacement knee joints are round, because round is better". Ok, cute ad, but I'm left wondering why the other replacement knee joints are apparently elliptical. Are there advantages to that ? StuRat (talk) 04:36, 13 June 2013 (UTC)

I don't know the ad you are referring to, but are knee joints round? I don't know how anatomically correct an image like this is, but they certainly look quite eliptical to me. As to advantages, the knee doesn't move through 360 degrees, probably only about 140, if you compare a 140 degree arc of a circle to the 140 degrees arc of the kind of "not very eccentric" ellipse we see in the previous image, there's probably very little difference, they're both round arcs, you really need 180 degrees before an arc and a circle look much different (depending which arc you chose of course). One difference I can however imagine is weight distribution and this could play a large factor because wear of artifical knee joints is a main consideration, knee replacement is generally only offered to old people because young people would wear them out too quickly. Vespine (talk) 06:52, 13 June 2013 (UTC)

It's certainly not necessarily or obviously true that "round is better" anyway. Sure, for a wheel on a car, an elliptical wheel results in varying ride height and torque requirements that would be a disaster. But for a limb joint, it's not at all clear that there wouldn't be advantages. Just off the top of my head, I could imagine the following possibilities:

• Firstly, as an elliptically jointed limb rotates, the limb would change in length as the bearing point moves from the major to minor axis of the ellipse - but since the limb is only touching the ground during one part of the arc, that might not matter...but in a car wheel, this would result in massive vibrations at high speeds and sickening lurching at low speeds...also, since the wheels on front and back and either side of a car don't stay lined up - the car would rock from side to side and from front to back - and the suspension would be working continuously.

• Secondly, in a limb joint, when the minor axis of the ellipse is in place against the socket instead of the major axis, some fluid would presumably be trapped in that gap. This would result in fluid being continuously pumped in and out of the socket as you move the limb. That fluid flow might provide a lubrication function - or maybe deposit some material that resurfaces the socket over time - or perhaps have some other important biological function such as delivering oxygen or flushing out bacterial infections. Doing that wouldn't be necessary in an artificial limb - but it could very well be needed in nature.

• Thirdly, with wheels, the driving force is at the central axle - so the torque requirement from the motor would change as the wheel rotates and alternately raises and lowers the body of the car and the effective diameter of the wheel changes - this would clearly be a bad thing. But our limbs are powered by muscles that don't operate at the center of the joint - so the torque requirements wouldn't change significantly - and the idea that the amount of force required to move the limb would change over the arc that it swings through might actually work in favor of efficient motion. You could easily imagine a situation where your leg would be a little longer when in contact with the ground, gradually shortening as you moved it during a stride - this would allow your body weight to help propel the limb during the "power stroke" at the cost of increased torque as the leg is straightened to plant it back on the ground again. That could very easily reduce the load on the muscles and let you run faster.

I don't know whether any of those things are true...but the point is that it's very far from obvious that a round joint would be better than an elliptical one - and the analogy with car wheels is quite utterly bogus.

Since it's much harder to machine and polish an elliptical surface than a round one - I find it hard to believe that the other artificial joint manufacturers would have made elliptical joints if there wasn't good reason to do so.

SteveBaker (talk) 12:48, 13 June 2013 (UTC)

Thanks. Yes, I realize that this is a typical ad which fails to make any real argument to support it's case, so was looking for the real advantages/disadvantages of each. StuRat (talk) 03:58, 14 June 2013 (UTC)

Triple integral integration by parts

We are all familiar with the integration by parts formula:

$\int f{\frac {dg}{dx}}dx=fg-\int g{\frac {df}{dx}}dx.$

Does there exist an "analogous" formula for the following case?

$\iiint f\left({\vec {\nabla }}\cdot g\right)dV=\cdots$

— Trevor K. — 04:46, 13 June 2013 (UTC)

You should post this on the math desk. Someguy1221 (talk) 04:51, 13 June 2013 (UTC)

$f\partial _{k}g_{k}=\partial _{k}\left(fg_{k}\right)-g_{k}\partial _{k}f$ Count Iblis (talk) 12:11, 13 June 2013 (UTC)

And if you're not familiar with the Einstein notation used by Count Iblis in his very concise answer, try

$f{\vec {\nabla }}\cdot {\vec {g}}={\vec {\nabla }}\cdot \left(f{\vec {g}}\right)-{\vec {g}}\cdot {\vec {\nabla }}f$. Dauto (talk) 14:16, 13 June 2013 (UTC)

And don't forget to use Gauss theorem to solve the integral of the divergent. Dauto (talk) 14:20, 13 June 2013 (UTC)

Naming an apple rust (fungus)

The apple tree in front of my work place (middle of Germany) started to look strange and on the under side of the leaves I found nice purple red looking marks. I made a few images and I need some help to give the little fungus the right name . It looks like some rust (fungus), but I could not find any images of a purple red one.

some apple rust

• 
  no magnification
• 
  5x
• 
  10x

--Stone (talk) 07:47, 13 June 2013 (UTC)

I think not. Google images for eriophyid mites. See http://www.whitecanker.net/Maple,%20Norway/Maple,%20Norway.asp and http://www.forestryimages.org/browse/detail.cfm?imgnum=5424246 It seems it is a Gall caused by mites. 196.214.78.114 (talk) 13:56, 13 June 2013 (UTC)

(Awesome pics BTW - hope you add them in the relevant sections.) 196.214.78.114 (talk) 14:02, 13 June 2013 (UTC)

Good call, it does look a little like a fungus, but I think mite gall is correct. Our article is at Eriophyidae, which only has a picture of a much larger type of gall. So the pics could probably be added there, even without a species-level ID. SemanticMantis (talk) 18:22, 13 June 2013 (UTC)

What's wrong with this one-pot synthesis?

Recently I have used orgsyn problems as my crossword puzzles, and I like to find cheaper more feasible alternative routes to known drugs. So what's wrong with this one-pot synthesis -- it seems too simple or else it would have been more popular:

1. Start with any essential oil containing mostly safrole (like the ones on eBay)
2. Markovnikov acid-catalyzed hydration of safrole into a secondary alcohol
3. Oxidize secondary alcohol into ketone using TEMPO and bleach
4. React the ketone with N-Methylformamide (solvent) and formic acid (reagent, 5 equiv?) via the formamide form of the Eschweiler–Clarke reaction. Bleach will be destroyed, chlorine will be released (leave room)
5. Add strong acid to hydrolyze the substituted formamide to release formate and MDMA.

You can then recover the MDMA using the usual workup for amines, purify using chromatography etc.

What's wrong? 71.2.172.65 (talk) 18:42, 13 June 2013 (UTC)

Other than being illegal in many jurisdictions? --Jayron32 19:39, 13 June 2013 (UTC)

"Other than being illegal in many jurisdictions?" - Then what's wrong - LEGAL advice is the kind WP cannot give... ;) — Preceding unsigned comment added by 217.88.169.113 (talk) 12:45, 14 June 2013 (UTC)

They aren't asking for legal advice, but rather chemistry advice (and possibly medical advice, if "What's wrong with..." is meant to include the medical consequences). StuRat (talk) 20:13, 14 June 2013 (UTC)

• This was closed, and any further talk belongs on the talk page. μηδείς (talk) 20:32, 14 June 2013 (UTC)

(apparently most of us disagree with that, fortunately) Wnt (talk) 22:36, 14 June 2013 (UTC)

Alright, this being organic chemistry, I'm hard pressed to unpack the question to begin with. So let's lay it out just to help those of us who want to understand the question! According to the OP:

Reportedly, safrole is subject to acid-catalyzed hydration. (Markovnikov's rule says that the OH ends up on the atom with more alkyl constituents, i.e. the inner one) I'm not so clear on how easy this is - certainly if chemists could just add NH3 across that bond and have it come out the way they want, they'd be done!

With the tail of this molecule now being -CH2-CHOH-CH3 (a secondary alcohol) oxidize it to ketone with TEMPO and bleach, i.e. -CH2-C(=O)-CH3.

The next step ... confuses me. I'm thinking it is basically a Leuckart reaction to convert to -CH2-C(-NH2)-CH3, which is a two step process of adding formamide and then getting rid of the "form" bit.

Now all these do indeed look like they are on the road from A to B; the trick is - is there some incompatibility between the reagents used, or is there something about one of them that would damage the rest of the compound? Wnt (talk) 23:00, 14 June 2013 (UTC)

Genetic contributions of parentals in haplodiploidy

In the haplodiploidy section in the article of sex-determination it states:

"If a queen bee mates with one drone, her daughters share ¾ of their genes with each other, not ½ as in the XY and ZW systems."

The premise is that female bees are diploid and male bees are diploid.

Here is what I do understand:

1. Daughters posses genetic material from both a father bee and a mother bee
2. Sons possess genetic material from a mother only

Here's what I don't understand:

1. If each (diploid) daughter possesses one of each chromosome from father bee and one of each from mother bee, how do they share 3/4 of their genes with each other? According to my calculation, they should have the potential to share 100% of their genes with siblings (if the same chromosome was receveived from mom) or 50% (if a different chromosome was received from mom) because they always have the same chromosomal contribution from haploid dad. Was the comment above meant as an average of 100% and 50%? That seems odd.
2. Do sisters in XY necessarily share only 50% of their genes? They necessarily share at least 50%, but can't they share 100%?
3. So it seems to me that in both haploploidy and XY, sisters can share 50% or 100%, but not 75%.

Thanks! DRosenbach ^{(Talk | Contribs)} 19:39, 13 June 2013 (UTC)

The 3/4 figure is the center of a range, but it isn't all that large of a range. The thing that you are missing is that meiosis (cell division for sexual reproduction) involves genetic recombination -- so the result has 50% of the parent's genome, but each chromosome is a mixture of the two that come from the parent. Looie496 (talk) 19:49, 13 June 2013 (UTC)

1) Yes, the 75% figure is the average, and the 100% or 50% are for each chromosome seperately, and due to interchanging sequences, even a single chromosome can be partly from one parent and partly from the other.

2)Sisters in the XY system (e.g. human sisters) can share anything between 0% and 100% of their genome (not counting the identical X-chromosome that they got from their father), but statistically the similarity is rarely far removed from 50%, except in the case of identical (or semi-identical) twins.

3)As mentioned before, the 75% is the average for the entire genome. - Lindert (talk) 20:20, 13 June 2013 (UTC)

(EC) No, male Hymenoptera are Haploid, females are diploid, that's why it's called haplodiploidy (Oops, I see now you probably just made a typo). Also, as Looie points out, there are ranges. You are correct that these are best viewed as averages, more precisely expected values. Human siblings share 50% of genes on average, but it can be higher and lower in individual cases. It is in fact highly unlikely that a given pair of human siblings share exactly 50% of their genes. And now that I've helped answer, I must point out that we are misusing the term "gene" here. Genes are loci, alleles are the information or "code" present at the loci. So really, we should say that bee sisters share 75% of their alleles, on average. SemanticMantis (talk) 20:23, 13 June 2013 (UTC)

Two things are important: chromosomal crossover in meiosis, which means that each chromosome produced for a gamete is a mixture of parental chromosomes (in the female only in this case, because the male only has one of each). Also note there are 12 chromosomes in the first place, each of which is independently segregated. So 50% or 100% similarity is exceedingly unlikely. Note though that all the male alleles (SemanticMantis is right, though it is so common for "gene" to be misused) go to each offspring, so that 50% of the similarity is reliably so. Wnt (talk) 03:10, 14 June 2013 (UTC)

What kind of microscope do oceanographers use?

Hi, I am from Kiribati, a small country in the Pacific Ocean and I'd love to study oceanography. Thank you. I'm 20 year old. — Preceding unsigned comment added by IchbinKiribatisch (talk • contribs) 22:30, 13 June 2013 (UTC)

Probably optical microscopes. Plasmic Physics (talk) 22:52, 13 June 2013 (UTC)

Oceanography is a very broad discipline, many oceanographers would never touch a microscope. A closely linked field is Marine biology which I imagine is more what you are thinking. Further, microscopy is a field of study in it self and knowing how to use a microscope effectivley takes a bit of practice. You are probably better off buying a general purpose or second hand biological microscope, the kind they use at universities. There are many buying guides online that you should have a look at to give you an idea of what to look for. Vespine (talk) 06:00, 14 June 2013 (UTC)

The article reads that there are subfields within oceanography, which includes biological oceanography. Biological oceanography studies the incidence and distribution of a particular microbe as it relates to the oceanography of a particular site. So, no, I'm not thinking of marine biology. Plasmic Physics (talk) 07:06, 14 June 2013 (UTC)

See WP:Reference desk/Humanities#What's the difference between a marine biologist and an oceanographer? where the OP asked a related question. Roger (Dodger67) (talk) 07:40, 14 June 2013 (UTC)

Spa chemistry

I'm a new home spa owner. (It's a soft-side, if anyone is interested.) I'm kinda confused by how pool chemistry works. I always thought that acidity vs. alkalinity were dependent -- if the pH is 7, adding acid will lower it, adding alkali will increase it. But pool chemistry appears to work not as I expect -- there's a separate number for "total alkalinity" as opposed to "pH". So at the moment, the pool is reading simultaneously too high alkalinity and too high acidity. As a chemist might ask, wtf is going on? What's the science here? --jpgordon^{::==( o )} 22:44, 13 June 2013 (UTC)

Your mistake is in equating alkalinity with pOH. It's not. It's the total capacity of a system to neutralize added acid. Systems at the same pH (or pOH) can have radically different alkalinities. Read our article on it: Alkalinity. Dominus Vobisdu (talk) 22:55, 13 June 2013 (UTC)

OK. That makes sense -- but it doesn't help me figure out what to do to rectify the water when the alkalinity is too high and the pH is way low. Do I need to keep adding more and more acid until the alkalinity starts to drop? But then how do I raise the pH to neutral (or higher) without sending the alkalinity right up again? This goes to applied science, I guess. --jpgordon^{::==( o )}

Yes. If you are starting at pH X and want to bring it down to pH Y, you will have to add more acid to do so if the alkalinity is high.

Generally, high alkalinity is not a common problem in pool water. The main problems associated with it are maintaining a stable pH, and turbidity. If you have problems with high alkalinity, read about how to lower it here: [[17]] and [[18]]. Consult a professional if you can't manage on your own. Dominus Vobisdu (talk) 23:14, 13 June 2013 (UTC)

I might add that high alkalinity at low pH is probably caused by a high CO2 concentration. It takes a lot of time for the CO2 to leave the water, especially in a large pool that doesn't get much use. It can be speeded up somewhat by aeration. Dominus Vobisdu (talk) 23:26, 13 June 2013 (UTC)

This is a 240 gallon spa, not a swimming pool. The general conditions are irrelevant; the specific problem is starting with untreated well water (delicious!) known to have high alkalinity to start with. Anyway, thanks. --jpgordon^{::==( o )} 06:08, 14 June 2013 (UTC)

Alkalinity is almost always caused by CO₂ dissolved as CO₃^2- or HCO₃^-. This can be driven out with heat and aeration, so I would suggest running your spa jets and heater for a few hours a day for a week to solve the issue (if it is really causing you an issue that is). Simply adding acid won't really solve the problem; the CO₂ will be stabilized as H₂CO₃, and the alkalinity will increase as soon as you try to bring the pH back to neutral. This site recommends using soda ash to increase the pH and remove alkalinity. This works because NaCO₃^- is a weak base, but it also forces other carbonate species out of solution via the common ion effect. 202.155.85.18 (talk) 07:57, 14 June 2013 (UTC)

June 14

Dense storage of positrons using superconducting coil?

Electrons can be "densely stored" in a superconducting wire coil and circulate as long as cyronic temperature is maintained. The Cooper Pairs (presumably) do "not knock" in to the coil. Could the same apply to positrons? If it did, positrons could be densly stored, allowing energy storage one hundred times more powerful than nuclear fusion, possibly allowing starship propulsion or anti-matter bombs. Switch off the cooling and the whole lot would annilhilate with total conversion of matter to energy. Some people have said I am irresponsible making this idea public, but making anti-matter is inefficient so only large states could do this. (Trevor Loughlin) — Preceding unsigned comment added by 91.224.27.227 (talk) 11:31, 14 June 2013 (UTC)

Wouldn't the superconductor also need to have antinuclei to conduct positrons? 139.193.214.10 (talk) 13:21, 14 June 2013 (UTC)

Funny post. The funniest part was "Some people have said I am irresponsible making this idea public". Dauto (talk) 18:21, 14 June 2013 (UTC)

In reality, positrons can be circulated in storage rings. The beams fly through a near-perfect vacuum, and are kept in position using magnetic fields. If you have a lot of positrons, you can do almost anything you like with them; but if you direct a beam of positrons into a wire - supercooled or not - the positrons will rapidly annihilate - because the mean free path is very short and the collision frequency is very high in condensed matter. Positrons are not easy to come by - so people who have access to them typically don't waste them - the particles are kept in ultra-high vacuums for as long as possible. Nimur (talk) 19:14, 14 June 2013 (UTC)

The best method we have yet discovered for producing positrons is a machine at Lawrence Livermore labs that is the size of a house and produces 10 billion (10¹⁰) positrons every 30 minutes by zapping a gold brick with a petawatt laser(!). Each positron (and each electron that you're going to annihilate it with to produce energy) weighs in at around 10^-30kg - so the results of 30 minutes production on this expensive machine is 10^-20kg of antimatter. E=mc² and c² is around 10¹⁷m/sec. So the amount of energy you get from an antimatter "explosion" produced by 30 minutes of work by this massive machine is somewhere near 2x10^-3 Joules - which is about 1/500th the energy produced if you drop an apple from a height of one meter. The energy stored in a AA battery is about five million times greater.

The energy it takes to fire the "Titan" laser in the positron creation machine is hundreds of Joules. So having a great way to store positrons isn't going to lead to amazingly powerful positron batteries or anything. SteveBaker (talk) 20:11, 14 June 2013 (UTC)

From the linked source: "... the electrons each break apart into a lower-energy electron and its anti-matter opposite, a positron.". This would violate charge conservation, so I think the source is not reliable. 95.112.240.62 (talk) 21:38, 14 June 2013 (UTC)

The "linked source" is a brief and general-purpose news summary - it's bound to "gloss over" minor details (like the laws of physics) - for the purposes of brevity. If you require scientifically-accurate descriptions of the laser phenomena that Steve mentioned, you might read the publications section at the Jupiter Laser Facility at Lawrence Livermore. It lists several published, peer-reviewed papers on the production and measurement of positrons in the laser laboratory. Nimur (talk) 22:48, 14 June 2013 (UTC)

I like to hijack the original question and reformulate it:

1. Can electrons really be "densely stored" effectively anywhere? Superconducting coil or not, electrons repulse each other due to the electrical charge.
2. Obviously, positrons would annihilate with electrons in normal matter. But if we would find some technical trick to strip the electrons off but still keep the nuclei in place and the positrons squeezed between them, wouldn't the positrons react with neutrons?

95.112.240.62 (talk) 19:41, 14 June 2013 (UTC)

I guess it depends what you consider "dense." There are a lot of electrons densely packed in ordinary, regular, condensed solid matter! I don't think you'll get denser packing of electrons-per-cubic-meter than what you'd find in a dense atomic lattice - like lead or uranium or a lump of any other other favorite heavy element. There's a few dozen moles of electrons per mole of uranium, or about a septillion electrons per cubic centimeter (plus or minus a few orders of magnitude).

For your second question - everything I've ever learned about positrons concerns either of two scenarios: (1) positrons, carefully isolated in an almost perfect vacuum (i.e., not interacting with any matter), for the purposes of some particle experiment; or (2) positron emission followed almost immediately (i.e., after a very short duration of travel-time) by a positron-electron collision event. For example, in medical imaging (PET), the positron is emitted and it exists just long enough to bump in to the first atom it encounters, annihilating one electron and releasing a bright shiny pair of easily-detectable photons.

I'm not familiar with any other type of positron absorption event. Though part of me wants to say that positron emission might be reversible, thinking along a symmetry argument, I've never heard of positron absorption by a nucleus. Nuclei absorb electrons, not positrons. So: probably the math doesn't work out - and positron emission is not reversible even in theory; but even it it's possible, it's so exotic an interaction as to be completely un-discussed in most of the experimental physics community; or maybe somebody else has spent more time studying experimental particle physics has some additional insight. Nimur (talk) 23:52, 14 June 2013 (UTC)

To add my own ignorant question to the mix: what controls the odds of electron-positron annihilation? I imagine that, given that an electron is "blurrier" than a proton, a positron ought to be localized to a region larger than a hydrogen atom, and likewise the electron it "orbits" just before annihilation. They're not point particles heading toward each other, right? Is there some period of time when they just sit there, one amidst the other, waiting for a probabilistic event to happen? And does that event depend on their parameters of motion - spin, angular momentum, velocity relative to one another, what kind of orbital they're in? Is it remotely conceivable to engineer an electron-positron material that somehow reduces the odds of annihilation by a measurable amount? Wnt (talk) 01:45, 15 June 2013 (UTC)

Two different cicada species?

I asked this question on July 16, 2011, and currently my area is again covered with cicadas. Are the ones of 2011 and the ones presently here different species? It certainly hasn't been 13 years since 2011. Peter Michner (talk) 15:30, 14 June 2013 (UTC)

OK, it looks like 2011 was Brood XIX and the ones I'm seeing now are Brood II. Peter Michner (talk) 15:41, 14 June 2013 (UTC)

Yep, you got it. Technically, you may also see a few of the Tibicen mixed in as well, but they have probably not emerged yet this year. SemanticMantis (talk) 15:53, 14 June 2013 (UTC)

Each brood may be made of several different species though. Rmhermen (talk) 17:03, 14 June 2013 (UTC)

If members of each brood can only mate within the brood, then I'd expect them to drift into different species eventually, so there must be a mechanism for interbreeding. Overlapping breeding periods is the obvious mechanism. I wonder, though, how the offspring of a cross-brood mating decide which brood they belong to. Is it always the mother or father ? StuRat (talk) 20:20, 14 June 2013 (UTC)

These questions are addressed at magicicada, and refs therein. Magicicada is a genus, comprising ~7 spp, and 13-year dormancy is dominant over 17-year cycles. SemanticMantis (talk) 21:09, 14 June 2013 (UTC)

Who is right?

Newton says that Gravity is a force which accelerates objects toward each other.

Let an apple is dropped from Pisa tower. T₁ is the striking time of earth and apple.

• Gravity force of earth on apple = F₁ = m₁g_e = m₁GM/R² where g_e=GM/ R² = gravitational accelaration of earth (say 9.8 m/s/s)
• Gravity force of apple on earth = F₂ = Mg_a = MG m₁/r₁² where g_a=Gm₁/ r₁² = gravitational accelaration of an apple

Where G= Gravitational constant, M= Mass of earth, m₁= Mass of an apple, R= Radius of earth, r₁=radius of apple

Although F₁ = F₂ but since earth can also be seen from apple and accelerate towards it with g_a , therefore, an apple look a lot to drop to the earth as compared to the falling of earth toward apple which is so minuscule to be perceived as g_e >>>> g_a.

Let a steel ball of radius 1 meter is dropped from Pisa tower. T₂ is the striking time of earth and ball.

• Gravity force of earth on ball = F₃ = m₂ g_e = m₂GM/ R₂ where g_e =GM/ R² = gravitational accelaration of earth (say 9.8 m/s/s)
• Gravity force of ball on earth = F₄ = Mg_b = MGm₂/r₂² where g_b=Gm₂/ r^₂2 = gravitational accelaration of apple

Where G= Gravitational constant, M= Mass of earth, m₂= Mass of ball, R= Radius of earth, r₂=radius of ball

Although F₃ = F₄ but since earth can also be seen from ball’s gravitational field and accelerate towards it with g_b, therefore, a ball look a lot to drop to the earth as compared to the falling of earth toward the ball which is so minuscule to be perceived as g_e >>>> g_b.

Since F₁ = F₂ ≠ F₃ = F₄ as g_b > g_a therefore T₂ < T₁ by definition but Galileo was first to demonstrate that in the absence of air, all things would truly fall with the same acceleration and 300 years later demonstrated this by the crew of Apollo-15 on the lunar surface (which has gravity & also lacks air) by dropping a hammer and a feather. So what would u think who is right?

• Galileo
• Newton or
• If Both then how

162.157.235.1 (talk) 23:02, 14 June 2013 (UTC)Eclectic Eccentric Kamikaze

My naive answer: Apollo_15#Lunar surface gives Galileo's theory as "all objects in a given gravity field fall at the same rate, regardless of mass". The ball, or apple, or feather, or hammer, contributes to the gravity field, although not much. Thus, both are right. (I think your fourth bullet point was meant to end with "ball", not "apple", by the way.)  Card Zero  (talk) 00:24, 15 June 2013 (UTC)

You're talking about forces, but you should be talking about accelerations if you are interested in times. Someguy1221 (talk) 00:42, 15 June 2013 (UTC)

The Earth cannot be treated as a rigid object here. When you drop an object, a shock wave travels through your body to your feet and then it moves into the Earth. Then as the object approaches the Earth, the gravitational force it exerts on the Earth increases, but this doesn't affect distant parts of the Earth at the same time. Finally, when the object hits the ground, you get another shock wave that travels into the Earth.

One can still argue that the total momentum of the Earth should clearly increase as the object approaches its surface due to conservation of momentum, but even this statement is not without problems. This is because the Earth's total momentum is not a precisely defined quantity, according to quantum mechanics an object of mass M in a thermal bath at temperature T will have a typical spread of its momentum of order sqrt(M k T). For the Earth, taking T to be room temperature, this is of the same order as the momentum of the ball. This means that the probability that the Earth's center of mass state changes during the fall is close to zero (this is why you can observe interference phenomena, a photon taking one path or another, bouncing off different mirrors doesn't cause the state of the mirrors to be different in the two different paths despite conservation of momentum, due to the finite spread in the momentum of the mirrors and other macroscopic objects). Count Iblis (talk) 01:00, 15 June 2013 (UTC)

The shockwave Iblis mentions starts at the point of contact between the Earth and body, and moves upward from the feet to the head, while travelling downward from the sole of the foot into the earth. μηδείς (talk) 01:05, 15 June 2013 (UTC)

First off, your distinction between R and r1/r2 is wrong. The appropriate distance to use is the distance between the center of masses - which is the same for the apple acting on the earth and the earth acting on the apple. For the earth, a few dozen meters more or less doesn't make much of a distance in scale when compared to the radius of the earth, so we typically don't care about the distinction. However, the difference between the gravitational field (from the apple) on the surface of an apple versus an earth radius away is substantially different, so you need to be careful to use the center-of-mass to center-of-mass distance there. So gravity force of apple on earth = F₂ = Mg_a = MG m₁/R² where g_a=Gm₁/R² = gravitational acceleration of an apple at the distance of the radius of the earth. More to your point, you're trying to apply Newtonian mechanics to an non-inertial reference frame. Because the earth is so massive, the distinction between taking the earth as a reference frame and an inertial reference frame is negligible. This *isn't* valid when you're using the apple/ball as a reference frame. The deviations there become significant. To properly treat the system with the (accelerating) apple/ball as the fixed reference frame you need to add in fictitious forces, which makes your third law assumptions invalid. (You can't assume g_a and g_b keep a constant value once things start moving, changing your assumptions about how accelerations lead to times.) -- 205.175.124.30 (talk) 02:03, 15 June 2013 (UTC)