Wikipedia:Reference desk/Archives/Science/2009 August 1

= August 1 =

Swine flu
Is the swine flu wrongly named ??? I read in wiki article that the present strain of H1N1 virus is different from that present in pigs.Infact it says it first passed on from a man to the pig. Also what is so special about swine flu ,that it is hitting the news almost everyday???Is it not just like any other viral infection or a flu??pl clarify thanks.117.193.132.197 (talk) 07:22, 1 August 2009 (UTC)


 * The articles "Swine influenza" and "2009 flu pandemic" have the answers to your questions. "Swine influenza" is so named because the virus is endemic in pigs. It is thought that certain mutations ("reassortment") have caused a strain of swine influenza to become more readily transmissible among humans. Axl  ¤  [Talk]  09:26, 1 August 2009 (UTC)


 * It certainly is a poor choice of name, because it causes people to behave totally illogically. See 2009 swine flu outbreak actions concerning pigs...Every pig in Egypt was slaughtered in an effort to prevent a disease transmission mechanism that simply doesn't exist.  Khanzir was locked away from curious public for the same reason.  Sadly, we never seem to learn the lesson that naming things inappropriately causes panicky people to initiate useless and often costly responses to serious problems. SteveBaker (talk) 18:19, 2 August 2009 (UTC)


 * In the case of Egypt, they actually had ulterior motives to kill the pigs: since the only consumers of pork in Egypt are "infidels", they killed all the pigs to collectively punish the "infidels" (especially the Coptic Christian community) and force them against their will to comply with the shariah law regarding pork consumption. The so-called "swine flu" and the fear of contagion was only an excuse they needed to present to the so-called "international community" to justify these actions. 98.234.126.251 (talk) 05:23, 3 August 2009 (UTC)


 * Quite possibly - but would they have been able to do that if we'd called it "Mexican flu" or "Fort Dix flu" or "H1N1-2009" ? SteveBaker (talk) 23:51, 3 August 2009 (UTC)
 * My point exactly -- if it wasn't called "swine flu" then they wouldn't have that excuse to kill the pigs. If we called it "Mexican flu", though, then that would give them an excuse to arrest/isolate/deport (or even lynch) any Mexicans who happen to be in Egypt -- and they would've done that, especially since most Mexicans are Catholic. 98.234.126.251 (talk) 02:03, 4 August 2009 (UTC)

Uncertainty principle
I have just started to tackle on this subject. The part of explanation which seems most easy to understand (for me) is Uncertainty principle. This question is from there. It says: If the wave extends over a region of size L and the wavelength is approximately λ, the number of cycles in the region is approximately L / λ. The inverse of the wavelength can be changed by about 1 / L without changing the number of cycles in the region by a full unit, and this is approximately the uncertainty in the inverse of the wavelength, And I think the inverse of the wavelength can be changed more exactly by about $$ 1 / L + \lambda $$, not by 1 / L, without changing the number of cycles in the region by a full unit. If so,
 * $$ \Delta(\frac{1}{\lambda}) = \frac{1}{L + \lambda} $$

and multiplying by h, and identifying $$ \Delta P = h \Delta (1 / \lambda) $$, and identifying $$ \Delta X = L $$, $$ \Delta P \Delta X = h \frac{L}{L + \lambda} $$. Does that not mean if lamda is enough large, uncertaity becomes small? Like sushi (talk) 11:22, 1 August 2009 (UTC)
 * No. Consider the case of $$\lambda$$ as large as possible, i.e., $$\lambda=\infty$$.  In order to change that situation by one whole cycle within length $$L$$, i.e. to go from 0 cycles in length $$L$$ to 1 cycle in length $$L$$, you have to go from $$\lambda=\infty$$ all the way down to $$\lambda=L$$, which would result in $$\Delta(1/\lambda) = 1/L$$.  Red Act (talk) 19:32, 1 August 2009 (UTC)
 * It has become clear. No matter it is from what number of cycles to the next mumber of cycle, $$ \Delta(1/\lambda)=1/L $$, because $$ 1/\lambda $$ are n/L and n+1/L.
 * Thank you.
 * Like sushi (talk) 01:18, 2 August 2009 (UTC)
 * One more question. The above process includes changing the inverse of the wavelength without changing the number of cycles in the region by a full unit. If we are to measure only one particle, there seem to be no way of knowing the number of cycles in the region, on the other hand, if we are to measure a bunch of particles, capturing the shape of the wave seems possible, and therefore the wavelength and position.
 * Like sushi (talk) 06:12, 4 August 2009 (UTC)

Power line racket - What is it?
What are these things? What do they do? I see them occasionally on power lines. If it matters, this is in the US, Vermont more specifically. Dismas |(talk) 13:05, 1 August 2009 (UTC)


 * It's a form of power line tensioner, used to keep the wire under mechanical tension. Our tensioner article needs work. Nimur (talk) 13:34, 1 August 2009 (UTC)
 * I'm not 100% convinced they are tensioners, especially the second image - the device seems to be hanging on the wire, and not strongly attached in the way one would expect a tensioner.
 * (However if they are tensioners) then the article Overhead lines may be a better choice - they are common on electric railways - I've attached images of two on railway electrical lines - although a slightly different design - they should give a good idea of how they work and what they are doing :Spannfjader.JPG 2008 Station Javalaan (03).JPG —Preceding unsigned comment added by 83.100.250.79 (talk) 17:20, 1 August 2009 (UTC)
 * I would speculate that the device in the original photos is likely a cable shortener and the cable is possibly a telephone cable rather than electric. This would allow the telephone company to intentionally insert some extra length into that segment of cable which could be used if the cable later needs to be rerouted, possibly due to anticipated relocation of the utility poles.  This would avoid the need to splice in a new length of cable, which is no trivial task.  -- Tcncv (talk) 21:11, 1 August 2009 (UTC)

I've seen some of these too, they usually have a few turns of cable wrapped around them and are strapped to the line. Tcncv sounds right to me, in the case of a downed power line they might need the extra length. Presumably, when the company is hanging (laying?) power lines, they use more cable than they expect to need (better than using less than is needed). And it's probably more economical to just roll up the extra cable and have it be usable later than just cut it off and be useless. ZS 01:17, 2 August 2009 (UTC)
 * But isn't it a phone cable and not a power line? Edison (talk) 02:05, 2 August 2009 (UTC)
 * The two images that I posted are of the same device. They're just taken from two different angles.  And yes, it is about 2-3 inches below the line that it's attached to.  And we do have four new houses potentially going up on our road (as much as it bothers me to say it), so they may have put in extra cable for them.  Dismas |(talk) 02:08, 2 August 2009 (UTC)
 * The cable needs to be longer than its path anyway so it can be raised and lowered for maintenance purposes. But the fact that it is limited to a minimum radius bend suggests fibre optics to me. —Preceding unsigned comment added by 92.19.119.89 (talk) 21:58, 2 August 2009 (UTC)
 * Power lines are generally one conductor per wire, so it is straightforward to jumper in an extension to raise them for house moving. Phone cables may be multiple conductor (other than ancient rural party lines) so splicing would be very time consuming, and spooling several extra feet of cable might be sensible. Edison (talk) 00:50, 3 August 2009 (UTC)


 * In my (rural) neighborhood they appear in pairs, and there is a loop of cable that goes from one, to the other, then back along the primary line -- kind of like a pulley sytem. I've observed the local cable company working on them, so assumed they are television cable trunk lines -- they're noticeably heavier than the runs that to go the houses.  They're used to store extra length of cable, as mentioned above, anywhere from 50 to a couple hundred feet.
 * --DaHorsesMouth (talk) 02:37, 3 August 2009 (UTC)


 * Cable television isn't available in my area. Dismas |(talk) 03:14, 3 August 2009 (UTC)


 * It's also possible that these devices function to accommodate thermal contraction of the wire during extreme cold weather. FWiW 98.234.126.251 (talk) 06:04, 3 August 2009 (UTC)


 * Perhaps it IS a pulley system? where they expect to be shortly stringing additional wires? a pulley system that runs along an already installed wire, like a flying fox, would certainly make it easier to string the next new wire. Once they reach a pole, they'd have to transfer it to the next section. (This is not even OR, it's a WAG). - KoolerStill (talk) 11:07, 3 August 2009 (UTC)


 * In 2013, the description field for Dismas's images was changed to read:
 * Popularly known as a "snowshoe", this is a reel used to store extra slack deliberately left in optical fiber cable runs on poles to facilitate maintenance. Splicing optical fiber is a precision operation that can't be done on the pole itself, only on the ground. Therefore the installation crew leaves several hundred spare feet of fiber in cable runs next to junction boxes, enough so the junction box can be removed from the pole and brought to ground level for servicing. The extra cable is wound in several hairpin loops on a pair of reels like this, separated by 50 feet or so. Optical fiber lines like this are usually used to distribute cable television signals, or less often to carry internet lines or telephone trunklines.
 * And in 2017 the images were renamed from "Power racket" to "Optical fiber snowshoe, Vermont".
 * These fiber snow shoes are also called Fiber Storage Units, or FSUs. -- ToE 06:25, 27 August 2017 (UTC)
 * , thank you very much! I wasn't aware that the image had been updated with such great information. † dismas †|(talk) 02:38, 28 August 2017 (UTC)

image processing help.. required.
i have collected data of a gas turbine flame(at different equivalence ratio) using image processing toolbox of matlab .i understand that i have to use neural network toolbox to optimize the process.if any one could give me some ideaabout what could be optimized and how it could be done in neural network toolbox. sam 220.225.98.251 (talk) —Preceding undated comment added 14:07, 1 August 2009 (UTC).


 * It's very important to use the word "optimize" carefully. Take a look at optimization - there's a lot of subsets there.  MATLAB has very powerful tools for the mathematical operation of optimization, which means solving for the optimal numerical solution.  If the built-in MATLAB tools are insufficient, the CVX tool ("CVX: Matlab Software for Disciplined Convex Programming") is a common add-on.  If you are using the word "optimization" to mean that you want to "improve the efficiency" or speed up the process, then you need to explain your task a little better.  I also recommend that you do not use the term "optimize" when referring to general improvements to efficiency, because (as you are working with MATLAB, a numerical computation environment), "optimization" has a very specific mathematical meaning here.  Nimur (talk) 07:16, 2 August 2009 (UTC)

huge moth, species unknown
huge moth, species unknown

Found in my backyard this summer. If someone can identify the species, the image can go in an article. The third pic with a pen beside it shows how big it is. Are you ready for IPv6? (talk) 15:27, 1 August 2009 (UTC)


 * Looks like an Imperial moth, Eacles imperialis. Impressive, aren't they?  Acroterion  (talk)  15:30, 1 August 2009 (UTC)


 * I live in Northern Nevada where summer here is 100F each day. In the morning and sometimes all day these things rest near my bug zapper.  They're really sluggish to get them moving again and have to spend several minutes warming up before they can fly.  I don't know if that helps determine things.  Are you ready for IPv6? (talk) 15:51, 1 August 2009 (UTC)


 * It is some sort of sphinx moth, in the family Sphingidae. It may be Smerinthus cerisyi, but I don't know with certainty. Calamus Fortis  04:33, 2 August 2009 (UTC)

So which article should it go in? Are you ready for IPv6? (talk) 21:14, 4 August 2009 (UTC)

It's Pachysphinx occidentalis. I live in Northern Nevada as well and have seen them flying around. — Preceding unsigned comment added by 207.197.50.67 (talk) 08:40, 3 May 2011 (UTC)

orange juice safety
I bought a pint bottle of orange juice yesterday morning, opened it up and drank about a quarter of it directly from the bottle, which surely got some saliva and germs into it. I screwed the cap back on with the idea of taking it to work and finishing it there, but forgot about it, so it's been sitting at home at room temperature (maybe in the 70's during the day, it's not terribly hot here) for the past 24 hours or so. Taking a sniff of it, it smells ok. Is it likely to be teeming with dangerous pathogens by now despite that? I guess this is really a general question of whether food spoils to the point of unsafe-ness even without starting to smell or taste bad. Thanks. 67.117.147.249 (talk) 18:25, 1 August 2009 (UTC)
 * We can't really give definitive advice as to safety - but orange juice is fairly acidic, and won't go off rapidly, (also if your own saliva was that full of pathogens you'd probably be dead already :) ), one day is ok, I'd put it back in the fridge, warm orange juice is not that tasty.
 * In a general case it depends on the food, some keep better than others, yoghurt is something I regularly eat past the sell by date since it's a foodstuff that by 'design' is supposed to keep.
 * Other stuff - eggs, pork, beef, chicken are much more likely to give you food poisoning even when they smell and taste ok.83.100.250.79 (talk) 18:38, 1 August 2009 (UTC)


 * I beg to differ on warm orange juice, it's delicious (especially freshly squeezed). Along with its acidity, orange juice contains alot of sugars aswell, which act as a preservative. --Mark PEA (talk) 19:37, 1 August 2009 (UTC)
 * Obviously I'm statisically insignificant, but I regularly drink orange juice, straight from the carton, and leave it in my bedroom (which tends to have closed doors and windows, so gets warm and humid) for three or four days before it gets finished. Interpret that information as you like. 90.195.179.49 (talk) 21:50, 1 August 2009 (UTC)


 * Warm orange juice, especially fresh-squeezed, will ferment pretty quickly. It isn't harmful to drink that way, but the loss of sugar and increase in acidity make it pretty unpleasant, to me at least. Looie496 (talk) 21:53, 1 August 2009 (UTC)
 * Well I've had freshly squeezed OJ from a warm airport terminal in Spain several times and I just can't help but sink the whole plastic cup in one it is so darn palatable :-). Orgasmic is a better word, but maybe it's just me. --Mark PEA (talk) 23:44, 1 August 2009 (UTC)

There's a saying, "Drink apple juice because OJ kills." Are you ready for IPv6? (talk) 21:13, 4 August 2009 (UTC)
 * Hahahahaha! LOL! (BTW, did you know there's talk about letting him out of jail?) 98.234.126.251 (talk) 01:24, 5 August 2009 (UTC)

Crosswind landing
What's the HIGHEST crosswind velocity in which a Beech Queen Air can land? (Assume the worst case, that the wind is blowing at RIGHT ANGLES to the ONLY available runway. Also, if it matters, assume that the runway is wet but NOT icy, and that the pilot has more than 10 years' worth of experience, and also that she's a firm believer in using the sideslip method rather than the crabbing method for landing.)  Thanks in advance! 98.234.126.251 (talk) 19:06, 1 August 2009 (UTC)
 * In the crosswind chart of the FAA’s Airplane Flying Handbook, page 8-16, a crosswind landing in a direct crosswind is in the “danger zone” at wind velocities above 15MPH. But I think that might just be a sample crosswind chart, that doesn't really pertain to any specific aircraft.  According to the same page, in airplanes certified after May 3, 1962, the FAA requires the demonstrated crosswind velocity of an airplane to be included on a placard in the airplane.  Does the Beech Queen Air in question not have such a placard?  Red Act (talk) 20:17, 1 August 2009 (UTC)
 * It should -- unfortunately, I'm not a professional pilot and have never been in the cockpit of a Queen Air (or, indeed, in the cockpit of any twin-engine airplane). I'm just a petroleum chemist who's also a part-time writer of detective fiction, and I need this info for a short story that I'm in the process of writing.  I think I'll just go with 15 knots as the maximum crosswind velocity.  Thanks, and clear skies to you! 98.234.126.251 (talk) 21:23, 1 August 2009 (UTC)
 * You should be aware that these figures are always pretty conservative. A skilled pilot in an emergency situation will mostly succeed at quite a bit above the rated figures -- it's scary as hell though.  I was in a small plane once that landed with the nose pointed upwind at what seemed like 45 degrees, and it was a white-knuckle experience for me, although the pilot didn't seem fazed.  (It also matters a lot whether the wind is constant or gusty.) Looie496 (talk) 21:41, 1 August 2009 (UTC)
 * So, a pilot with more than 10 years' worth of experience might be able to land a light twin (like the Queen Air) in a steady 20-knot crosswind? What do you think? 98.234.126.251 (talk) 21:48, 1 August 2009 (UTC)
 * For the sake of realism, also keep in mind that the tower might not allow a landing outside of the conservatively-estimated limits. Planes are regularly delayed or redirected to alternate landing sites due to bad weather.  Nimur (talk) 22:25, 1 August 2009 (UTC)
 * True enough, but the field in question is a tiny airstrip in northern Canada and doesn't have a control tower. Also, the plane in question is critically low on fuel (about 1/2 hour's worth of fuel remaining) and cannot reach any alternate landing site. 98.234.126.251 (talk) 22:30, 1 August 2009 (UTC)
 * You may wish to discuss this with wikipedia admin CambridgeBayWeather, who I believe is the airport manager for a small airstrip in northern Canada, and who (in my modest experience) is an entirely helpful chap. Veritably, the horse's mouth. -- Finlay McWalter • Talk 22:56, 1 August 2009 (UTC)

Well according to this the stall speed of a Queen 88 is 70 knots. According to the Canada Flight Supplement "Aircraft of United States manufature are designed to withstand groundlooping tendencies on landing in 90-degree cross-winds up to a velocity equal to 0.2 (20 per cent) of their stalling speed." and points out the owners manual will have the information. So for the 88 it's 0.2 x 70 = 14 kts. Not much wind needed to cause a problem. There is some more about it here. Also if your pilot is landing anywhere but (for example) Rankin Inlet or Churchill, Manitoba, then the runway might be gravel and the wetness component for a small aircraft will not be as bad as landing on a paved strip or for a larger aircraft. The airstrip won't have a tower but will probably have a Community Airport Radio Station or a Flight Service Station, who can give the winds and altimeter setting but can't deny or permit the landing. The pilot is in command and they make the choice. Enter CambridgeBayWeather, waits for audience applause, not a sausage 03:03, 2 August 2009 (UTC)
 * Thank you very much, CambridgeBayWeather, this was very helpful of you. {**Loud applause**}  This pretty much confirms the info I have so far.  (BTW, I think I'll have my pilot land her plane at Coral Harbor (I know, that's technically not on the mainland), if it matters.)  Thanks again, and clear skies to you! :-) 98.234.126.251 (talk) 05:34, 3 August 2009 (UTC)
 * The deafening silence is just everyone holding their breath watching the Queen coming in. They don't want to add to the gusts by breathing. -KoolerStill (talk) 16:02, 2 August 2009 (UTC)
 * Wow! That's suitable for publication in a mass-market suspense-thriller novel!  Note that including the above theatric scene-building element in the novel may require licensing under GFDL... Nimur (talk) 16:38, 2 August 2009 (UTC)

Tin chloride for noble metal detection
SnCl2 is used to detect traces of noble metals in solutions. For example, it give us a purple color, if solution contains gold (AuCl3). Can anybody write the equations of reaction between tin chloride and gold chloride in solution and the reactions of tin chloride when it is used to detect platinum and palladium. Renaldas Kanarskas (talk) 19:09, 1 August 2009 (UTC)

I think that the overall equation of the reaction between SnCl2 and AuCl3 is as follows:

3SnCl2 + 2AuCl3 = 3SnCl4 +2Au

or in other words it's a straightforward redox reaction. As for the second part, I can't remember the exact equations off the top of my head, but I think that in those reactions SnCl2 also reduces the platinum / palladium ions to the metal while itself picking up 2 extra chlorines to form SnCl4. FWiW 98.234.126.251 (talk) 19:35, 1 August 2009 (UTC)


 * Wikipedia article about SnCl4 do not show it is purple ... What substance gives this purple color?--Renaldas Kanarskas (talk) 12:28, 2 August 2009 (UTC)
 * Colloidal gold is/can be purple see also "Purple of Cassius"83.100.250.79 (talk) 13:26, 2 August 2009 (UTC)

Species of peafowl


Is the pictured Pavo an Indian Peafowl or a Green Peafowl? Reading the articles, I can't see how they appear differently, other than the head, which is hidden in this picture. Nyttend (talk) 20:03, 1 August 2009 (UTC)
 * By the way, it could be Indian — this picture was taken by the same photographer at the same zoo. However, the two photos were taken over a year apart, so they're not necessarily the same bird.  Nyttend (talk) 20:10, 1 August 2009 (UTC)
 * Hi, I took both the pictures under discussion. They were in fact taken on the same day because I've only been to Paignton Zoo once ever, in July 2003 (a look at the Image Description Page for both pictures confirms that). Sorry, but I didn't know at the time what species I was looking at and have no way of now finding out (short of posting the pictures to the zoo, which someone else is welcome to do). - Adrian Pingstone (talk) 20:55, 1 August 2009 (UTC)
 * My apology — I misread the upload dates as the dates when the photos were taken! Arpingstone, would it be reasonable to say that it's the same bird?  It appears to me that the Indian species has a blue head and the Green species a green head (hardly a surprise :-), so if these are the same bird, the photo shown here is Indian.  Nyttend (talk) 22:08, 1 August 2009 (UTC)
 * I'm sorry to be so unhelpful but I can't remember how many peacocks the zoo had (it was five years ago). Therefore it's not possible to say that the pictures show the same bird - Adrian Pingstone (talk) 22:26, 1 August 2009 (UTC)
 * Not surprised that you can't remember — how many little details do I remember from five years ago? Thanks for your help!  To get back to the original question — can anyone identify the bird from behind?  Nyttend (talk) 23:06, 1 August 2009 (UTC)

I used to keep peafowl and my best guess is that it is a Spalding, a cross breed of the Indian and the green. 67.193.179.241 (talk) 13:59, 2 August 2009 (UTC) Rana sylvatica
 * I sent a note to Paignton's inquiry email address, and just a few minutes ago received a reply: "That is an Indian Blue Peafowl." Thanks for the help!  Nyttend (talk) 14:08, 3 August 2009 (UTC)

What is a petoscope?
It is something to do with Proximity fuzes. 78.146.251.127 (talk) 22:53, 1 August 2009 (UTC)


 * More specifically, it's the toroidal lens that focuses the incoming light from the target area onto the photocell of an optical proximity fuze. The way it works is when the photocell "sees" the shadow from the target, the drop in current activates an electric circuit that sets off the fuze and makes the bomb explode. 98.234.126.251 (talk) 23:58, 1 August 2009 (UTC)

Have you got any source or evidence for that please, apart from just guessing after reading the proximity fuze article which I had also read? 78.147.244.14 (talk) 14:12, 2 August 2009 (UTC)


 * My source is, which is externally linked from the article Proximity fuze. 98.234.126.251 (talk) 05:39, 3 August 2009 (UTC)

Now someone has written an article about the Petoscope - thanks. 78.146.237.28 (talk) 21:55, 3 August 2009 (UTC)