Wikipedia:Reference desk/Archives/Science/2009 December 28

= December 28 =

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

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

The Excel worksheet may be downloaded from personal diet example. 71.100.6.153 (talk) 01:37, 28 December 2009 (UTC)
 * For what it's worth, and I have not the faintest idea what it's doing, what it's for, or whether the numbers it shows actually make sense, it loads and appears to produce some sort of results in my completely non-Microsoft environment (NeoOffice 3.0.1 on Mac OS X). So if it's meant to illustrate something specific to Excel or SOLVER these may not be appropriate articles to link to it. Maybe you could simplify it and generalise it to illustrate something about linear programming? Tonywalton Talk 02:00, 28 December 2009 (UTC)
 * Actually there are many good examples of this very process all over the net especially at many university sites that want to get students up and running quickly in the use of Excel and its Solver add-in. I had been using a computer program written in Visual Basic v6 to do the same thing but the Excel layout here is actually simpler and more adaptable to other uses. The idea here is the application of linear programming specifically to finding meals based on set number of calories and meals per day that produce a balanced diet according to any particular dietary regimen choice rather than intending to serve as a general application of linear programming. Some food or dietary article then me thinks best. 71.100.6.153 (talk) 02:30, 28 December 2009 (UTC)


 * IMHO, this is not the kind of thing Wikipedia needs - as you know - this is not a "HOW TO" guide. However, since you evidently don't agree with that assessment, I think you should go to one or more of those pages and start discussing it on the 'Talk:' page there.  If there is widespread support for this amongst the authors of those articles - then you can go ahead and do it - if not, then it's better to quietly give it up because of the "not being a how-to guide" thing.   You could (I suppose) "Be Bold" and just add it and see what happens - but since my personal inclination is contrary to that, I'd just go in there and revert your change - so you'd end up having to discuss it anyway. SteveBaker (talk) 02:46, 28 December 2009 (UTC)
 * A better converter would certainly help make it more presentable but what about just the link to the actual spreadsheet. In what article might that best find an acceptable place? 71.100.6.153 (talk) 02:52, 28 December 2009 (UTC)


 * Is this a project which would be better suited to the mandate of one of our sister projects &mdash; perhaps Wikiversity? TenOfAllTrades(talk) 03:23, 28 December 2009 (UTC)
 * Presenting the whole concept of linear programming is definitely worth the facility offered by the Wikiversity since for one thing the entire economy of the former Soviet Union used it to replace supply and demand but what I would hope to accomplish here is to provide individual readers interested in a mathematical means of creating a balanced diet that meets whatever calorie need they might choose both an example and a place to start, which might then lead them later to a full blown Wikiversity course. 71.100.6.153 (talk) 06:06, 28 December 2009 (UTC)

strange astronomical sight


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


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


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


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

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

I posted a picture of the moon with a 22ohalo. did the phenomenon you saw look anything like that? Dauto (talk) 14:15, 28 December 2009 (UTC)
 * If someone wouldn't mind fixing the currently incomprehensible initial sentence in the 46° halo article -- I would do it myself, but I haven't a clue what it's trying to assert, and I left a message on the talk page which doesn't look like it's been visited about 60 times in the last year by no one who edited except for a page assessment.  DRosenbach  ( Talk
 * I took a stab at cleaning up the language. It looked like some serious grammar issues, but I think I was able to make heads and tails of it. -- Jayron  32  20:58, 28 December 2009 (UTC)

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


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


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


 * The blue moon term started as a misprint in the 1946 issue of Sky & Telescope, but since then it's found its way into popular culture. Here is a link about moon halos from Spaceweather.com. ~ A H  1 (TCU) 01:31, 1 January 2010 (UTC)

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

Extraterrestrial intelligence
The universe is so large and there may be many undiscovered galaxies, which means possible undiscovered stars and planets. There may be undiscovered planets in habitable zone. Then why scientists deny the possibility of existence of extraterrestrial intelligent life forms? --Qoklp (talk) 10:50, 28 December 2009 (UTC)
 * Do they? Vimescarrot (talk) 11:48, 28 December 2009 (UTC)
 * Take a look at the SETI article, there are an awful lot of scientists involved in actively looking for extraterrestial intelligence.  Sp in ni ng  Spark  11:54, 28 December 2009 (UTC)
 * I was going to say something along the same lines. A good scientist probably would not "deny the possibility of existence of extraterrestrial intelligent life forms?". There may be a lack of verifiable evidence from reliable sources. People claim to have been taken on board 'spaceships' by 'aliens' but not too many of these people are 'rocket scientist' types (I may be being a bit uncharitable here). Space is certainly very big, lots of galaxies, star systems, planets etc. It would be a "waste of space" wouldn't it? I recall that Carl Sagan believed that it was very possible. --220.101.28.25 (talk) 12:03, 28 December 2009 (UTC)
 * See also Rare Earth hypothesis and Drake Equation --220.101.28.25 (talk) 12:14, 28 December 2009 (UTC)


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


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


 * I remember seeing on Ripley's Believe It or Not! that it's illegal per US federal law to communicate with extraterrestrials. As for UFO reports, that's the scope of UFOlogy and might not be entirely scientific. ~ A H  1 (TCU) 01:27, 1 January 2010 (UTC)

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


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


 * OK, it sounds as a joke and it´s told as a joke. But how can you know that it didn´t happen at least once?--Quest09 (talk) 20:05, 28 December 2009 (UTC)
 * You could ask that about any joke told in the form of a story, couldn't you? Vimescarrot (talk) 20:09, 28 December 2009 (UTC)


 * There's a variation of this regarding testing urine for the sugary indication of diabetes, as well. (Which snopes has a page on, incidentally.) It's the kind of joke that professors like to tell. Har har. --Mr.98 (talk) 20:18, 28 December 2009 (UTC)
 * Well, diagnosing diabetes by tasting the urine (if it's sweet there is glucose in it and the patient is probably diabetic) is a genuine diagnostic technique. It isn't used these days since we have little sticks that change colour when exposed to glucose, so doctors prefer those. Urine is perfectly sterile and safe to drink, there is really no downside to the technique. --Tango (talk) 20:47, 28 December 2009 (UTC)
 * I myself have seen it with my own eyes. Intended as a joke, of course, and with urine (well, yellow liquid) rather than a corpse. Tevildo (talk) 20:25, 28 December 2009 (UTC)


 * An apocryphal story also told about a chemistry professor who "tastes" a beaker of urine by dipping one finger in it and sucking another finger. Professors like their jobs, which is why you can be pretty sure this never happened. - Nunh-huh 20:24, 28 December 2009 (UTC)
 * Yeah, my 9th grade bio teacher did this with urine, too.  DRosenbach  ( Talk 20:33, 28 December 2009 (UTC)


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


 * Since the term "guts" may refer to any part of the Human gastrointestinal tract it is not obvious that the OP means the cadaver's anus, nor how gustation of rectal debris might advance one's education in anatomy. To research further on the subject that interests the OP, see this article and the acronym ATM; tutorial videos produced by dedicated professionals are available but deprecated since they do not provide health warnings, and there are probably somebody's mothers and sisters there. Cuddlyable3 (talk) 22:58, 28 December 2009 (UTC)
 * This joke is also in Mark Perakh's collection of Russian jokes.  bibliomaniac  1  5  23:05, 28 December 2009 (UTC)
 * Drifting gently away from the strict topic, but my father recounts having seen a more elaborate version of this prank while in a military hospital ward, which involved a spurious request to the duty nurse for a bedpan, the surruptitious insertion therein of limeade and a large cooked sausage, and a 'helpful' ambulatory inmate who, while returning the bedpan to the nurse paused, picked up the dripping sausage and bit off a chunk remarking "There's not much wrong with him." 87.81.230.195 (talk) 01:49, 29 December 2009 (UTC)


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

If we inject oxytocin into a female
Human female or any cow - whatever is at hand- would she start producing milk? --Quest09 (talk) 20:03, 28 December 2009 (UTC)
 * As our lactation article explains, there is a lot more needed than oxytocin. Looie496 (talk) 23:16, 28 December 2009 (UTC)
 * Oxytocin is used on many dairy farms to get certain cows to let down when they're being milked. It doesn't make the cow produce any (more) milk to begin with though.  If it's used on a consistent basis, the cow will eventually need it in order to let down at all.  Dismas |(talk) 03:40, 29 December 2009 (UTC)

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

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

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

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

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

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

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


 * The two big challenges I see are that it requires a lot of moving parts to move very large volumes of gas, and also that the heat capacity of air (particularly stratospheric air, at rather low pressure) is quite limited; that means that we need to move large volumes of air into contact with our system, and that the chilling/warming cycles may take a long period of time. Both of those factors mean a lot of balloons and some costly equipment.
 * While I'm not familiar with such a generator operating in the manner you describe, there are a number of pilot projects which exploit temperature differences between surface and deep-ocean water. Our article on ocean thermal energy conversion gives the details.  In those systems, they avoid the problem of collapsing and inflating balloons and reeling cables in and out by moving the ammonia working fluid up and down through fixed pipes. TenOfAllTrades(talk) 21:26, 28 December 2009 (UTC)
 * Yes, it would work. It's basically a Stirling engine with the hot and cold side separated by a great distance. Ariel. (talk) 21:30, 28 December 2009 (UTC)
 * Note that "it would work" is not the same as "would be a feasible way to generate electricity". There's lots of ways to technically generate electricity which, like this method, are not viable for commercial power generation.  You can generate electricity by paying people to run on treadmills, or by capturing cow flatulence in large balloons and burning it, or by any number of wildass methods, the question becomes if these methods produce enough electricity at a low enough cost to be viable.  I can't see where your method would... -- Jayron  32  21:42, 28 December 2009 (UTC)
 * Since cows are domesticated, wouldn't that example be a tameass method? 87.81.230.195 (talk) 01:37, 29 December 2009 (UTC)
 * At 10-20km the ammonia will be at reduced pressure so it needs a lower temperature to cause condensation than the boiling temperature at atmospheric pressure. Keeping the condensed ammonia liquid during the descent to warmer temperature could be done more reliably by locking it into a pressure vessel than in an unpressurized insulated tank. I am not sure how you prevent the balloon stabilising at an intermediate height. The weight of 10-20km tether is significant. Unless your "small engine" can pull in the tether faster than the balloon sinks, the tether and possibly the balloon will hit the ground.


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


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


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


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


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

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

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


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


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


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