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

= May 1 =

Elephants are good mimics?!?!
I was listening to NPR today - they had a piece about how Parrots can dance. They commented that parrots and elephants are the only species other than humans that can genuinely adapt their moves to the speed of the music and to more complex beat patterns. They went on to explain that the probable reason for that is that both parrots and elephants are good mimics!! The idea being that in order to be a good mimic, you have to be able to adapt to the rhythm of some other sounds in order to mimic them.

OK - but who ever heard of elephants being good mimics?! I can't imagine a talking elephant - what they heck would they mimic?

SteveBaker (talk) 00:14, 1 May 2009 (UTC)


 * The thing is, there are actually elephants all around you—they are such good mimics though that you never notice. I know a number of people who later turned out to be elephants. I once had a car that was actually an elephant. --98.217.14.211 (talk) 01:30, 1 May 2009 (UTC)
 * White, no doubt. Clarityfiend (talk) 01:44, 1 May 2009 (UTC)
 * Dancing elephants? That I'd like to see. Anyone know of an online video that shows it? —Preceding unsigned comment added by 98.17.34.76 (talk) 01:41, 1 May 2009 (UTC)


 * I don't know about a video, but did someone mention Stravinsky? --  JackofOz (talk) 03:36, 1 May 2009 (UTC)


 * You can see some elephant dance here http://www.youtube.com/watch?v=ecH16G05GC8 —Preceding unsigned comment added by Dauto (talk • contribs) 04:09, 1 May 2009 (UTC)

Here's a BBC online article about elephant and bird dancing: http://news.bbc.co.uk/2/low/science/nature/8026592.stm —Preceding unsigned comment added by 98.17.33.211 (talk) 08:08, 1 May 2009 (UTC)


 * Animals that mimic tend to be both social and intelligent. This is true for apes, parrots, dolphins and elephants. This link may be of interest, as well as the article Elephant_intelligence, especially the section Elephant_intelligence. What the evolutionary advantage of mimicking is, I don't know, but I assume it is related to communication between individuals. --NorwegianBluetalk 10:25, 1 May 2009 (UTC)


 * So there is at least one talking elephant...wow! I'd NEVER have guessed that. SteveBaker (talk) 15:41, 1 May 2009 (UTC)


 * Accounts by people who've worked with Asian elephants (I'm thinking in particular of the explorer Col. John Blashford-Snell, Hon. Life President of the CFZ to which I belong) suggest that elephants are routinely capable of learning to understand simple human speech (true speech, not merely a set of commands), as well as body language and even smells. Conversely, while elephants are obviously not physiologically well suited to reproduce human speech, humans are well able to learn elephant body language and human-audible sound signals, so mutual communication and even affections (or, sometimes, antipathies) readily arise, resulting in close elephant-mahout partnerships that may last decades. In such elephant-human co-operative contexts, there would be no pressing need for the elephant to learn to reproduce human speech, but doubtless they could if specifically tasked, and evidently can for their own amusement. (I second Steve Baker's "wow!")


 * Note that in one respect, the Asian elephant article is misleading. Modern working elephants (always female) are tamed but not domesticated, which implies captive breeding and consequent physical and temperamental modification in the descendant captive population. Captive elephants rarely breed, and most working elephants are captured from the wild and tamed. (It's possible that one or more populations of truly domesticated elephants once existed.)


 * As Norwegian Blue suggests, intelligent social animals largely learn both physical and vocal skills by mimicking their elders and peers ("monkey see, monkey do" and so forth), and can apply this skill to other aspects of their environments, including their interactions with other intelligent species. Humbling, when you reflect on it. 87.81.230.195 (talk) 18:32, 1 May 2009 (UTC)


 * Ever hear of ED the Talking horse, or Wiblur the mule from Greenacres, or the "Clever Haus" fraud? Mt point is that it anthropocentric to attributE "human" characteristics to non human animals. I find it arrogant but not "unnatural". 67.193.179.241 (talk) 11:57, 4 May 2009 (UTC)

Swine flu question
I read something interesting:

Does an early case of mild swine flu immunize one against a more severe case should this become a fully-fledged pandemic?

[response] People who are infected with swine influenza H1N1 will have immunity, or at least partial immunity, should there be a full-fledged pandemic.

But influenza viruses mutate constantly - they can become more or less severe.

If I understand this correctly, then shouldn't health officials take samples of the mild form of the virus, and prepare to give it to everyone, if ever a more virulent form of the virus appears? --Phenylalanine (talk) 02:09, 1 May 2009 (UTC)


 * This is essentially how vaccination works, using either a naturally weaker form of a virus (as when cowpox (hence "vaccination" from vache = cow) was first administered by innoculation to immunize against more serious smallpox), or an artificially weakened or dead version of the virulant form (accepting that "alive" and "dead" are contentious concepts where viruses are concerned).


 * As of now, governments and biotech firms worldwide will be striving to produce and breed an attenuated version of this particular new version of swine flu, but (a) it may take weeks to produce a suitable form (you have to minimize the risk of it mutating back to virulence, or being too strong to begin with), and (b) it will take months to breed enough of it and to manufacture the hundresds of millions of doses that, at minimum, may be needed (because the world don't have enough of the right equipment available). In the meantime you have to hope that the wild virus doesn't mutate again into a form still virulent, but sufficiently different that the immunization conferred by the tame virus vaccine doesn't work.


 * At the moment, we don't know why some cases of this virus are proving lethal while others are less so, so getting yourself infected with what you hope is a 'milder' form would be a very high risk strategy. 87.81.230.195 (talk) 02:40, 1 May 2009 (UTC)


 * Most influenza vaccines have been inactivated, only recently have live attenuated vaccines been widely used. For the 2009 A/H1N1 strain, it seems unlikely that they will attempt to perfect a live-attenuated strain in time for fall 2009; rather, an inactivated vaccine would be much simpler (more predictable in terms of safety and efficacy).  --Scray (talk) 02:49, 1 May 2009 (UTC)


 * You've suggested immunizing everyone, just in case. Here are some reasons why we don't:


 * 1) There is some risk with any vaccine (or any injection, really). Thus, the benefit needs to exceed this risk, for us to justify the vaccination.


 * 2) Immunizing everyone has a high cost associated with it. This money may be better spent on actual, current threats to public health than on possible future threats.


 * 3) If we get people to come in for vaccinations all the time when they don't really need them, they will get sick of being poked and not come in any more, even in cases where they really need to.


 * Therefore, the recommendations for flu shots are limited to people with reduced or suppressed immune systems, such as small children, the elderly, those with AIDS, those taking immuno-suppressants, etc. People who regularly come in contact with such individuals should also be immunized. StuRat (talk) 14:02, 1 May 2009 (UTC)


 * The problem here is that we don't know how virulent this disease really is. Taking the most extreme numbers from Mexico - we get 500 or so confirmed cases and 110 people suspected to have died from the disease which suggests a horrifying 20% mortality rate - very scary indeed.  However, we don't know how many unreported cases there are where people got a mild dose of the flu and got over it without reporting it - and of those 110 dead, only 12 are confirmed as having died from the flu rather than from something else entirely.  Taking the other extreme, we find that there have been 2000 reported-but-unconfirmed cases in Mexico and only 12 confirmed deaths - so the mortality rate could be as low as 0.5% - and there could easily be a million more people who have been infected who not only aren't dead and didn't report it to their doctors - but who aren't even showing symptoms - 12 deaths per million is a very mild strain of flu indeed!  Remember that tens of thousands of people die from regular old-fashioned flu every year - and nobody panics about that.


 * Here in the US, we've got just one death from 200 or more confirmed cases - so the 0.5% looks reasonable - until you realise that that one solitary death was from a 2 year old child who had contracted the disease in Mexico...the fact that she subsequently travelled to the US is rather irrelevent. So of the people infected inside the US, there has not been a single fatality.  The sample size is in no way statistically meaningful anyway.


 * Seen against a possible 0% fatality rate, doing ANYTHING to try to immunize people is a bad idea - simple, routine injection site infection might wind up doing more harm than good.


 * We simply don't have enough information yet. The prudent course is to prepare for large scale action but to actually DO nothing whatever (except, perhaps, to gag Joe Biden!).  SteveBaker (talk) 16:39, 1 May 2009 (UTC)


 * I'm not sure why we would exclude a death from a patient who contracted the disease outside the US. That still means there isn't a zero percent death rate, unless we think that Mexico has a different strain than the US.  (If so, it's nice of those germs to respects the border; that fence is really working.  We should get more illegal immigrants to build another fence with Canada.) StuRat (talk) 22:51, 1 May 2009 (UTC)

Bad idea, this virus is dangerous now since, even if it only kills half of one percent of those it infects (I'm guessing from bad statistics) nobody has immunity to it. Even a half of one percent of the human population is three million deaths. Tim Vickers (talk) 19:54, 1 May 2009 (UTC)


 * Let's not forget the great 1976 swine flu vaccine debacle. President Ford receives a swine flu inoculation - NARA - 7064718.jpg A mild outbreak of H1N1 influenza caused great panic among government officials and fears of a pandemic like the 1918 flu led to mass immunization of the U.S. public. President Ford was immunized before TV cameras. 40 million people were given the vaccine. Skeptics said "Tell me when the corpse collectors are calling out "Bring out your dead!" like in Monty Python and the Holy Grail and I'll consider getting the jab." The actual flu only killed only one person. The vaccine killed 25 people. 178,000,000 in the U.S. survived the "pandemic" without getting vaccinated. See a CDC article on the debacle. Edison (talk) 22:35, 1 May 2009 (UTC)


 * Thanks to all for your very helpful answers, and a special cheers to SteveBacker for calming my media-driven fears. --Phenylalanine (talk) 00:32, 2 May 2009 (UTC)


 * Why is this being discussed here - anyone read the medical disclaimer? – ukexpat (talk) 01:53, 2 May 2009 (UTC)


 * A disclaimer for the Wikipedia reader is not guidance for responding on the RefDesk. We do have a guideline that deals with advice on the RefDesks, and it does not prohibit a discussion of medical issues - we just need to avoid giving advice.  --Scray (talk) 16:09, 2 May 2009 (UTC)


 * And even then it's advice to individuals about which treatment they should have that we should avoid. Recommendations on national health care policy (as it relates to distribution of flu shots) is fair game. StuRat (talk) 15:20, 4 May 2009 (UTC)

midlatitude cyclogenesis -- exactly how do low pressure systems deepen?
Can someone explain to me the whole process of deepening -- I did read the article, and I understand there is a surface level component and an upper atmosphere component involved. I just don't get how an initial turbulence developing around a minor disturbance in a stationary front triggers strengthening of a low pressure system. Winds will tend to circulate and spiral inwards into a low pressure system, but presumably, the low strengthens by convective updrafts. What reinforces the initial updraft? John Riemann Soong (talk) 05:25, 1 May 2009 (UTC)


 * When discussing an article, you should provide a link so readers can look at the article. Is Cyclogenesis what you're asking about here ? StuRat (talk) 13:48, 1 May 2009 (UTC)


 * As a general rule for weather systems the updrafts are reinforced by buoyancy due to latent heat released when water vapor condendes. Dauto (talk) 14:37, 1 May 2009 (UTC)

INVISABILITY CLOAK
I was reading an article on an invisability cloak that has been created by smoothing light around the object like water flows around an object. This is at present very small; what are the difficulties of making this on a large scale? Could you not group together X number of small parts to make it bigger?Chromagnum (talk) 05:49, 1 May 2009 (UTC)
 * For some information about the concept and the problems involved, see Cloak of invisibility and Metamaterial. Deor (talk) 13:01, 1 May 2009 (UTC)

To steve baker buddy about sodium
N''ote: This post continues the thread of question "What are the products of the reaction of sodium with Sand" April 29th, 2009. Plse don't start a new topic with a continuing thread. Thks.'' 76.97.245.5 (talk) 06:43, 1 May 2009 (UTC)

Hey, no offence, but the fact is, YOU ARE NOT GETTING THE POINT.

Understand this, when sodium reacts with ethanol, sodium ethoxide is formed. If it reacts with water, it forms NaOH with hell lot of exothermic activity. Now, if sodium reacts with SAND, yes SAND, not WAAATTTEEERRR or ETHAAANOLLL, are there any products formed? If u are unable to answer and say it's SPOON FEEDING, you might as well change the definition of SPOON FEEDING.

Thanks for ur concern —Preceding unsigned comment added by 123.49.43.236 (talk) 05:50, 1 May 2009 (UTC)
 * When sodium reacts with ethanol hydrogen is formed, this is easily found by searching on Google, Live Search, Yahoo or some other search engine for 'ethanol hydrogen reaction' and may be mentioned somewhere in one of our articles too (I didn't see it but didn't look that hard). If you know sodium ethoxide is formed you should also be able to work this out when writing a balanced equation. Hydrogen is also highly combustible. As our article mentions, it is also a exothermic reaction albeit not as strongly as with water. I expect you should know this if you are doing A-level chemistry. You have already stated that sodium probably does not react with sand although you are not sure. So let's see we have
 * sodium + water =


 * KABOOM!!!!!
 * sodium + ethanol = KABOOM?!? (at least a fire hazard)
 * sodium + sand = nothing (probably)
 * Let's say there's a sodium spill, which one would I choose to try and prevent anything nasty happening?
 * If you are still unable to answer the question, I don't know if we can help you, you may need a tutor who can help you learn critical thinking since frankly this is very basic critical thinking and if you can't even answer this you don't have much hope in your A-level let alone with your dreams to study in an American university
 * If you are now able to answer the question, then why couldn't you answer it before? You appear to have already guessed or researched enough to know most of what I've said here, none of it is new. If you weren't sure you were right then you should have simply offered your reasoning as I have done (well without the need to be so fancy) and people would have helped confirm you answer. This is what Steve, me and many of the RD want people asking homework questioners to do. Don't be afraid to be wrong, people usually won't and shouldn't make fun of you, unless perhaps you have shown absolutely no evidence of having done even the most basic research and thinking. When you show evidence of having thought about it and looked in to it yourself and just need confirmation, people will generally be more then happy to help.
 * Nil Einne (talk) 06:24, 1 May 2009 (UTC)
 * that's some big ass text there lol
 * Guys, I think you're being too harsh. The main issue in reactivity I suspect, is that sand is solid, and so is sodium. EtOH and HOH isn't. Let's say you brought your reaction conditions down to -20 degrees Celsius, and you brought sodium and solid octanol together. Would they react? Probably very very slowly.
 * The other real issue of course, is whether sodium's electron prefers to be transferred to SiO3 (radical), or OH (radical). Because we know if it's the former, then the reaction is definitely exothermic and the main obstacle is reaction conditions. John Riemann Soong (talk) 06:47, 1 May 2009 (UTC)

The Silicon in SiO2 isn't really acidic. It's in fact, not hydrogen, so it would take some effort to pry off. (Presumably, Na giving its electron to oxygen is more favourable than giving it to less electronegative silicon.) In fact, silicon and oxygen are fairly well ionically bonded (with some partial covalent character), so your first issue is dissolving that Si-O bond. Melting it sounds like a good option. SiO2 also reacts with hot NaOH to yield sodium silicate. I'm not sure if the high heat is required for solubility, or for driving an endothermic reaction, but Na reacts exothermically with water to yield NaOH, so a reaction between sand and sodium isn't that all impossible. Your main barrier is that both of your reactants are solids. For a non high-temperature alternative, perhaps "dissolve" (or crush) the sodium in a non-reactive organic solvent and pass it through a sand column chromatography mixture, and collect the appropriate eluent? I don't know what the yield would be, but it sounds like a possible mechanism. John Riemann Soong (talk) 06:35, 1 May 2009 (UTC)

Also, what about adding sodium, sand and water? Sodium hydroxide would be formed as an intermediate, the reaction would be exothermic, the hydrogen would ignite, making the sodium hydroxide even hotter, so now you have adequate delta-H to complete the reaction (I think?). Add in sand and you get sodium silicate. (Theoretically.) John Riemann Soong (talk) 06:38, 1 May 2009 (UTC)


 * I think you aren't quite getting the question. The OP isn't trying to get sand to react with sodium. They're just trying to work out what to use if they have a sodium spill. See and  for a history of this question Nil Einne (talk) 06:44, 1 May 2009 (UTC)


 * Maybe the questioner's obstacle to understanding is not knowing why sodium doesn't react with sand. (Yes, there are people like that, who know their chemistry but suck horribly at exam skills. What happened to WP:AGF?) I am curious though. I mean, suppose you tried to clean up the spill with n-decanol in subfreezing conditions. Would I get flame and burning? How do you clean up a spill with solid sand anyway? I would think some sort of (liquid) "nonreactive" organic solvent would be more effective. Is crown ether an option? John Riemann Soong (talk) 06:56, 1 May 2009 (UTC)
 * I think the idea is to use the sand to dilute the sodium so you can then sweep it up without dealing with highly reactive sodium (since the mixture would be much less reactive). The sand is also likely to absorb water and stop it reacting with the sodium. --Tango (talk) 08:09, 1 May 2009 (UTC)


 * I think we're over analysing the situation here. This isn't a question on how to clean up a sodium spill. It's a question on what a bystander should do if they come across a spill or the person carrying the sodium should do if it spills. The main thing is you need something accessible and easy to use. You just want to stop a fire or explosion before they get there. You are NOT supposed to be the one dealing with cleaning up a sodium spill. You let the people trained to do that deal with it. Nil Einne (talk) 08:45, 1 May 2009 (UTC)


 * The questioner gave no indication they wanted to know why sodium doesn't react with sand. They first stated they didn't think that sodium would react with sand. He/she then stated "if sodium reacts with SAND, yes SAND, not WAAATTTEEERRR or ETHAAANOLLL, are there any products formed". So I am AGF here. It appears the OPs problem is that they are not confident in their believe that sodium doesn't react with sand and therefore is unable to answer the question. It seems to me it is you that are not AGF since you are presuming that the OP's problem is that they have poor English or are otherwise unable to ask a simple question like "why doesn't sodium react with sand" when that is what they want to know and instead ask a lot of other stuff when they actually want to know something else. I prefer to accept an OP's question at face value particularly when they have given no indication they have trouble explaining what they want to know or have poor English. And I have made a good effort to explain the thinking which the OP needs to do to get the answer. As I have already stated, if the OP still can't get the answer, then they probably need further help from external sources. If the OP wants to know why sand doesn't react with sodium there's nothing wrong with that and they are welcome to ask, so far they have not. P.S. I should add that if the OP does have poor exams skills, your answers aren't exactly helping. When you are in an exam particularly an MCQ, you don't generally have time to analyse each answer carefully. Sometimes you have to rely on educated guesses if you aren't certain about something. In this case as I have already explained it appears to me the OP had sufficient info to be able to answer the question already. They may not be certain, and it's good practice to not only make sure you are right, but understand why you are right, in other words there's nothing wrong with the OP coming here to ask why sodium doesn't react with sand and the reference desk would welcome such questions. But there's no indication from the OP that they want to know that yet. Instead every indication is that the OP is still struggling with the question. In this case, distracting information like why sodium doesn't react with sand is unhelpful and unnecessary. If the OP to spends their time analysing each answer in this way, they're liable to run out of time and fail because that's not how you answer MCQs. Nil Einne (talk) 09:14, 1 May 2009 (UTC)

The Kaboom is energy! So you need to get energy from the reaction of
 * SiO2 + 4 Na -> 2Na2O + Si

The energy for the elements is normally zero. And the numbers for the other two you can get from the table of Standard enthalpy change of formation and the sodium oxide page. The numers are
 * SiO2 -911 Δ Hf0 in kJ/mol
 * Na2O −414.2 kJ/mol

You get two mol of Na2O for every mol of SiO2 so yo double that number. -911 is more negative than -828.4; this means that the SiO2 is energetically on a lower level and that it is more stable. You would not get energy from that reaction and without energy no KABOOM!!!!!.--Stone (talk) 08:12, 1 May 2009 (UTC)


 * What about sodium silicate formation? (Without the presence of water -- I assume some O2 would be sufficient?) John Riemann Soong (talk) 09:28, 1 May 2009 (UTC)


 * 2Na + 1/2 O2 + SiO2 = -911 kJ/mol < −1519 kJ/mol. Looks like a highly exothermic reaction here? John Riemann Soong (talk) 09:33, 1 May 2009 (UTC)


 * Yes, but what are the kinetics of that reaction? If the half-life of the reaction is 1000 years, it doesn't matter much if it is that exothermic, its not going to happen to any appreciable level.  Given that it's essentially a solid-state reaction, I imagine the kinetics to be quite slow.  Plus, I suspect the Na + O2 reaction to be fast enough that functionally, you would be reacting Na2O with SiO2.  --Jayron32. talk . contribs  13:44, 1 May 2009 (UTC)


 * Well then add water as a catalyst. One concern I suppose is that excess water will drive the reaction in the other direction, so I suppose the key is to add only enough water to make concentrated NaOH. (The water gets recycled.) John Riemann Soong (talk) 14:12, 1 May 2009 (UTC)


 * OK, so the question NOW becomes, "does a concentrated solution of NaOH react appreciably with Silicon Dioxide" and the answer of which is demonstratably "NO". After all, glass is just amorphous sand, and you can store NaOH in glass safely for years with no problem.  Given that, since a) the kinetics behind a Na - SiO2 reaction is likely prohibitively slow and b) Basic Na derivatives like Na2O and NaOH will not likely react at all the answer is STILL that sand and sodium should not react in any reasonable way.  --Jayron32. talk . contribs  18:08, 1 May 2009 (UTC)
 * Then why does the silicon dioxide article mention that it reacts with *hot* sodium hydroxide? It's the heat that matters, I think, for the activation energy. But that heat is readily supplied by the reaction of sodium with water. John Riemann Soong (talk) 06:43, 2 May 2009 (UTC)


 * I stand corrected. Thank you for finding that.  --Jayron32. talk . contribs  12:22, 2 May 2009 (UTC)

The easy way to answer this question: This MSDS |MSDS for sodium says to cover a large spill with dry earth, sand or other non-combustible material. So if the sodium supplier says to cover it with sand if spilled, I think it is a safe bet that sodium doesn't react with sand. No chemistry required. anonymous6494 13:57, 1 May 2009 (UTC)


 * I really don't appreciate all of the large font text and bitching at me, personally. I first told our OP to look in Sodium for the answer.  Then we got a follow-up question and it was evident that my first response did no good - I posted again to reveal the obvious fact that water is not the right choice (leaving us with a tougher choice between sand and ethanol).  Then I suggested the 'Precautions' section of the Sodium article - which I will now quote:
 * "Because of the reaction scale problems discussed above, disposing of large quantities of sodium (more than 10 to 100 grams) must be done through a licensed hazardous materials disposer. Smaller quantities may be broken up and neutralized carefully with ethanol (which has a much slower reaction than water), or even methanol (where the reaction is more rapid than ethanol's but still less than in water), but care should nevertheless be taken, as the caustic products from the ethanol or methanol reaction are just as hazardous to eyes and skin as those from water."
 * Since we're told in the question that there is a truckload of the stuff involved here ("more than 10 to 100 grams") - that quote allows anyone who takes the time to actually read the article to eliminate ethanol as a means to safely neutralize this LARGE sodium spill. You don't need any chemistry skills whatever - just the ability to read what the article says.  What remains from the list of choices is only sand - so that MUST be the correct answer.  I maintain that anyone who took the time to read the article (as I directed them to on TWO separate occasions) would have been able to find that out - and anyone who does not read the article when directed to do so in a Ref.Desk answer is demanding to be told the actual answer - which is spoon-feeding a homework answer.  That is most certainly not allowed per the Ref.Desk guidelines which the OP will find at the very top of this page - and which I had explained to the OP the first time around using the  template.
 * SteveBaker (talk) 16:19, 1 May 2009 (UTC)
 * I found it extremely confusing that people would AGF of someone who is clearly deliberately ignoring attempts to help them and just shouting at the attempted helper. I'm sorry if this isn't the done thing, but I have to say, I disapprove of the manner in which these people answered the OP's question - doing his homework, and then some. Steve gave the perfect answer days ago. Vimescarrot (talk) 19:55, 1 May 2009 (UTC)

geostrophic/gradient wind and equilibrium
Suppose the ideal condition of no friction, and a region of low pressure or high pressure. Wouldn't air slowly move across the isobars eventually? I'd suppose you have air parcels which once, having gotten into the system, would continue to blow parallel to the isobars. But the initial set up (non-equilibrium) required some displacement from high to low. So wouldn't there be slow but steady movement of air across the isobars? Just wondering. John Riemann Soong (talk) 08:07, 1 May 2009 (UTC)

The other thing I'm wondering about is the whole Coriolis Force and PGF balance. Why does the parcel keep its initial horizontal velocity component but not its velocity in the PGF direction. I assume when PGF = CF, there is no acceleration, but there is still velocity. Or is there sort of like an elastic spring motion? (Funnily, this is probably not related to the encouragement of troughs and wavelike motion, isn't it.) John Riemann Soong (talk) 08:07, 1 May 2009 (UTC)


 * The geostrophic equilibrium is a quasi-equilibrium between the pressure gradient force (PGF) and the coriolis force (CF). Assuming ideal conditions as you requested, we can make that an exact equilibrium in which case the two forces are equal and oposite. the CF is always perpendicular to the direction of motion, so for this idealised condition the PGF also must be perpendicular to the motion in which case the air motion would be exactly parallel to the isobars. All this is for an idealised condition. In the real world of course there is indeed some movement across isobars. I'm not sure I understand the second part of your question. Would you care to elaborate? Dauto (talk) 15:45, 1 May 2009 (UTC)

lifespan of dinosaurs
Anyone know what the longevity of a large dinosaur was likely to have been? Also, did they hatch from eggs? How long did they take to hatch? 207.241.239.70 (talk) 09:34, 1 May 2009 (UTC)


 * Our article Physiology of dinosaurs says: "It appears that individual dinosaurs were rather short-lived, e.g. the oldest (at death) Tyrannosaurus found so far was 28 and the oldest sauropod was 38. Predation was probably responsible for the high death rate of very young dinosaurs and sexual competition for the high death rate of sexually mature dinosaurs". Yes, they reproduced by laying eggs. I don't know how long their eggs took to hatch. Gandalf61 (talk) 09:51, 1 May 2009 (UTC)


 * How do we know it lived 28 years? (I don't have an account with Nature.com so I can't read the cited reference and the abstract doesn't provide enough information for me to understand.) A Quest For Knowledge (talk) 13:30, 1 May 2009 (UTC)
 * This article describes ways to determine age from human skeletons. Perhaps something similar?  --Sean 15:00, 1 May 2009 (UTC)


 * We might be able to come up with some guesstimates for how long the eggs took to hatch. Since this period tends to be longer for larger and more complex animals, we should probably start with the largest eggs we have now.  Those are ostrich eggs, and take 35-45 days to hatch.  (See Ostrich.)  Dinosaurs weren't really any more complex.  Some were smaller than ostriches, some were larger.  So, for the smaller dinos maybe we could cut that period in half, while, for the larger dinos we could maybe double it. StuRat (talk) 13:01, 1 May 2009 (UTC)


 * Let's also look at existing reptiles. According to Gila_monster, they have a 9 month incubation period. According to Komodo_Dragon, they have a 7-8 month incubation period.  However, since the current theory is that dinos were warm-blooded, like birds, rather than cold-blooded, like reptiles, this likely means their incubation period would be more in line with birds, too. StuRat (talk) 13:30, 1 May 2009 (UTC)


 * It's not clear why a dinosaur large enough not to get eaten would not live a very long time, considering the extreme ages their cousins alligators(70 years) turtles(100 years+) or parrots(80 years+) can reach.Edison (talk) 18:27, 1 May 2009 (UTC)


 * In the case of reptiles with slow metabolic rates, especially turtles, that's reason enough to explain high life expectancies. Dinos are thought to be warm-blooded with higher metabolic rates, though, which would tend to mean shorter life expectancy.  Parrots and people are a bit of an exception, though, which both have relatively long life expectancies despite being warm-blooded with higher metabolic rates.  In the case of people, a long childhood and learning that extends well into adulthood means a long life is needed to fully benefit from this knowledge.  Perhaps the same applies to parrots ? StuRat (talk) 22:39, 1 May 2009 (UTC)


 * I seem to recall that elephants live approximately as long as humans do, and they are both warm blooded and quite large. 65.121.141.34 (talk) 13:35, 4 May 2009 (UTC)


 * All other factors being equal, a larger species is likely to have a longer lifespan (and slower metabolic rate). StuRat (talk) 15:15, 4 May 2009 (UTC)

Mobile phone radiation
Moved from Miscellaneous Desk

A widely circulated sms message says that a mobile handset's radiation is 100 times higher when the battery is low. Is there any basis for this? —Preceding unsigned comment added by Ramkinkar (talk • contribs) 09:47, 1 May 2009 (UTC)


 * I very much doubt it. A mobile phone chooses its output strength based on the signal strength between it and the cell tower, battery power shouldn't have anything to do with it. If it does, then it would be lower radiation when the battery is low in order to conserve power (but I don't think that's the case, I think the battery just goes flat quicker if the phone requires a high powered signal). It should also be noted that, to the best of my knowledge, no study has found any evidence of harm to adults from mobile phone usage (I think results vary for studies on children). --Tango (talk) 10:30, 1 May 2009 (UTC)


 * The only effect that's been observed so far is that one side of the head is slightly warmer right after cell phone usage. However, this likely has nothing to do with "radiation", unless you're talking about infrared radiation/heat from the phone and the hand holding the phone. StuRat (talk) 12:51, 1 May 2009 (UTC)


 * Yeah. In fact, one side of your head will also be slightly warmer than the other if you hold a slab of plastic the size of a cell phone against your ear for five minutes. That's thermodynamics in action. -- Captain Disdain (talk) 14:10, 1 May 2009 (UTC)


 * This whole business of radio waves and other forms of radiation from cellphones being harmful in any measurable way has been spectacularly well researched and busted, busted, busted. Don't worry about it.  On the other hand - the number of car accidents and pedestrian accidents due to cellphones is off the charts...so if you need something to worry about - consider tripping and falling while texting! SteveBaker (talk) 14:49, 1 May 2009 (UTC)
 * Or walking into a lamppost. That hurts. --Tango (talk) 16:26, 1 May 2009 (UTC)


 * I do not consider it busted at all. Lets see the effect on young people in a few decades after they spend hours with a celphone stuck next to their head. A test is whether lefties get left side brain tumors compared to righties with right side brain tumors. Similar data came from US locomotive cab crews, where the engineer had his right side exposed to sunlight and the fireman had his left side exposed to sunlight many hours a day for many years. The melanoma distribution was as one might expect. Edison (talk) 18:25, 1 May 2009 (UTC)


 * There is a basis for the OP's rumour, although I would like to point out that the probability of this effect causing any harm is, in my opinion, infinitesimal. When the smarter ones among the anti-phone people realised that gigahertz radiation wasn't going to kill us, they had to look around for another way to scare us. What they came up with was a theory that the low-frequency pulses of current from the battery could create ELF radiation that would penetrate the body. Never mind the fact that every other gadget we use has exactly the same effect. Imagine the ELF on electric trains! Furthermore, they theorised, since phones operate using switch mode power supplies, they must draw more current from the battery as the battery voltage drops in order to keep the power constant, so the ELF gets worse. That's a true description of how some appliances work, although I don't know if it applies to mobile phones. I can't remember where I read this. I found a link to the general battery-ELF claim here, but it doesn't mention the bit about the battery running low. To track that down you would have to climb the Tower of Babel that is electromagnetic pseudoscience. --Heron (talk) 22:06, 2 May 2009 (UTC)

Radio waves and humans
Do radio waves travel through the human body, or does it block them? --TammyMoet (talk) 12:06, 1 May 2009 (UTC)


 * Such waves are not blocked by humans. &mdash; Lomn 12:50, 1 May 2009 (UTC)
 * Not as such, but the signal will be attenuated a little. Readro (talk) 13:00, 1 May 2009 (UTC)


 * Both the above responses are reasonable approximations of the truth. As a rough rule of thumb, electromagnetic waves (including radio waves) tend to interact very weakly with objects significantly shorter than their wavelength &mdash; they just don't 'see' them.  FM radio waves (frequency about 100 MHz) have a wavelength of about 3 meters (10 feet); AM radio waves (frequency about 1 MHz) have a wavelength of about 300 meters (1000 feet).  A typical human being standing in the path of a radio wave is about a third of a meter thick, resulting in weak attenuation of FM radio and virtually negligible effect on AM radio broadcasts.
 * Mobile telephone networks operate at frequencies between about 400 and 2100 MHz, depending on the jurisdiction. Those have wavelengths between (roughly) 1 meter and 15 centimeters (3 feet to six inches).  Consequently, those signals can be significantly attenuated by human-sized absorbers.  TenOfAllTrades(talk) 14:10, 1 May 2009 (UTC)
 * Some OR: I use a mobile phone as a music player when running, with a bluetooth headset. When I carry the phone in a belt bag and the signal has to travel through my body, the signal gets slightly chopped up (misses out bits about every thirty seconds, enough to be quite annoying). When the phone is in a pocket, this never happens. --NorwegianBluetalk 14:47, 1 May 2009 (UTC)

Thank you all for this - I got the mechanism as well as the answer! cool!--TammyMoet (talk) 17:36, 1 May 2009 (UTC)


 * It is a common experience that where someone stands strongly affects FM radio reception (where the antenna is just a wire hanging from the radio) or TV (nondigital) reception from rabbit ears. I have not noticed an effect on AM reception (much longer wavelength). So clearly the FM and TV signal is absorbed by, polarized by, refracted by or reflected from humans. Edison (talk) 18:21, 1 May 2009 (UTC)
 * In the antenna nearfield it becomes much more complicated because you are effectively loading the antenna's radiating element with a dielectric material consisting of an air gap and tissue, bones and the like. A human standing in the nearfield will not be directly affecting the RF, they will actually be affecting the antenna itself by tuning its various resonances. Readro (talk) 22:28, 1 May 2009 (UTC)
 * I'm thinking of cases where the antenna is compact and the person is many feet away, say 13 20 feet, but when they walk between the FM radio and the transmitting antenna, it affects the sound pretty dramatically. Edison (talk) 23:59, 1 May 2009 (UTC)

most common basics to staying beautiful
what are the most common basics to staying beautiful through the years —Preceding unsigned comment added by 94.27.137.4 (talk) 13:32, 1 May 2009 (UTC)


 * Avoid the sun - causes skin damage and wrinkles. For similar reasons do not smoke, do not drink. Stay slim - avoid junk food and saturated and other bad fats, eat plenty of vegetables and fruit. Edit added later: and get plenty of exercise, as rightly mentioned below. And read non-fiction and study so you get a depth of understanding to realise that personal beauty is not very important. A drawback with avoiding the sun is that you might not get enough Vitamin D which has health benefits, although overdosing on the vitamin damages your body. 89.241.144.80 (talk) 13:43, 1 May 2009 (UTC)


 * thanks! This is exactly what I was looking for (to the point that I almost listed avoiding the sun as an example of what I was talking about).  Any more answers along the same line are much appreciated. 94.27.137.4 (talk) 14:27, 1 May 2009 (UTC)


 * Take care of your skin, don't use overly powerful cleaning agents. Get plenty of sleep, eat lots of healthy foods and avoid greasy and fat stuff like deep fired.


 * And when all else fails - only hang out with people wearing beer goggles. SteveBaker (talk) 14:44, 1 May 2009 (UTC)
 * There's no such thing as beer goggles according to recent scientific research. Not sure where I read that - probably BBC news site. 78.145.24.191 (talk) 11:10, 7 May 2009 (UTC)
 * I'm sure SteveBakers comment was meant as a joke and not to offend, as signified by the small text he used to show it wasn't a serious answer. However I agree it would maybe have been better if he'd not commented at all


 * I didn't see anything offensive in SteveBaker's joke. For one thing, he didn't menssion gender at all so that rules out sexism, in case that's what was bodering you. Dauto (talk) 15:29, 1 May 2009 (UTC)


 * removed own comment; u can remove ur replies to it too if u want


 * Add exercising regularly to that list. Dauto (talk) 15:29, 1 May 2009 (UTC)


 * Good bone structure will take you through the menopause, assuming you're a woman. Also not being too thin, as your subcutaneous fat layer will ensure you don't get wrinkles while that lasts. A little embonpoint looks far more attractive than as if you've already gone through the embalming process IMNSHO! Do not smoke, ever: smoking is how they preserve ham and kippers! Eat plenty of fresh fruit and veg. Look in the mirror and tell yourself how lovely you are, for if you believe you are beautiful then other people will too! A positive mental attitude is both attractive and contagious. Oh and smile more often than you frown.--TammyMoet (talk) 17:33, 1 May 2009 (UTC)


 * Make sure that you get yourself two parents that stay lookin' good into senior years! Richard Avery (talk) 21:56, 1 May 2009 (UTC)


 * I second avoiding the sun (and sunlamps, tanning beds, etc.). I get less sunlight than the average vampire, and don't have a wrinkle on my face, as a result.  (Not bursting into flames and turning into dust is a secondary benefit, if you actually happen to be a vampire.) :-) StuRat (talk) 22:31, 1 May 2009 (UTC)

All absoulute rubbish beauty is in the eye of the beholder>>>the precieved beauty that is in magazines is what is above>>>plus the smoking and staying out of the sun is all about health nobody is ugly nobody is perfect you are what you are!! a better question would be what do i need to do to remain healthy? Dont step in front of a bus/smoke/eat/drink/breath or any other crap that is told to the masses about staying healthy>>example one of the oldest men to live on the planet chain smoked x number of smokes since his early teens; from china if i recall. Have fun is proberly the best answer life can be long or short just engoy itChromagnum (talk) 11:06, 4 May 2009 (UTC)
 * Ah, fatalism. You've ignored all the millions or billions of smokers who have died from lung cancer, heart disease, and so on. Some people shoot themselves in the head and still survive. 78.146.219.21 (talk) 09:05, 5 May 2009 (UTC)

See now smoking increase's the chances of you getting various types of cancer amungst other things but it does not give you lung cancer it may have been a contributing factor but still it didnt give you lung cancer. You have missed the point!!!!! the OP asked how to remain beautyfull through the years>>>she did not ask if smoking gave me lung cancer or about being shot in the head>>> if your geneticly predispositioned to look magazine beautyfull then i suppose that is that>> how ever what people percive as beauty is not what others percive as beauty as before beauty is in the eye of the beholder>>> not staying out of the sun dont smoke dont shoot yourself in the head ECT...that is a health issue which is not what the OP asked :) Chromagnum (talk) 13:20, 7 May 2009 (UTC)


 * I've noticed over the years that a lot of people in my social circles don't look their age; nonsmoking seems the most likely explanation. —Tamfang (talk) 07:18, 10 May 2009 (UTC)

medium oil
i want to know the components and composition of medium oil. —Preceding unsigned comment added by 119.154.21.28 (talk) 15:35, 1 May 2009 (UTC)
 * There is some information in the Oil paint article. But sadly medium oil itself hasn't been written (should probably be set as a redirect for now, but I'm having trouble getting reliable WP response right now...hope this post gets through:( DMacks (talk) 15:41, 1 May 2009 (UTC)

acid question
What is a bulk industrial chemical, probably acidic, that is used in both water treatment and circuit board etching? 65.121.141.34 (talk) 15:52, 1 May 2009 (UTC)


 * Iron(III) chloride. --Tango (talk) 16:24, 1 May 2009 (UTC)

Creation of A Death Note?
I am just curious, and I do have a few theories as to how it could POSSIBLY be done(Still need to do a bit more research, though my resources for knowlege are a bit limited at the moment), but I would like to simply ask..

Do you believe it can be done? And if so, how do you think I could go upon doing so?

Help, opinions, and critisism are all very much appriciated. Gothrokkprincess (talk) 15:59, 1 May 2009 (UTC)


 * This question has also been posted on the Misc desk (here). I suggest all discussion take place there, to keep things in one place. --Tango (talk) 16:20, 1 May 2009 (UTC)

Instincts in Humans
Why do some people, particularly women, sometimes place their hand over their mouth when they witness a scene of horror? For an example see http://news.bbc.co.uk/2/low/europe/8028317.stm. (Mouse over the photo to see the caption.) That was an involuntary response and therefore instinctive. Also, women sometimes scream when they experience fear - that is an instinctive cry for help. But what purpose does the hand-over-mouth instinct serve? (Some sociologists say that the only instincts humans have is fear of falling and fear of loud noises. I think we are loaded with instincts. These are two of them.) - GlowWorm. —Preceding unsigned comment added by 98.17.33.211 (talk) 16:41, 1 May 2009 (UTC)


 * Er, well everything you've listed here applies to both men and women. Sure there must be a reason, but I doubt it only applies to one gender. Personally my instinct when I see a scene of horror is to get out my camera and take a picture. —Preceding unsigned comment added by 82.44.54.169 (talk) 16:45, 1 May 2009 (UTC)


 * I don't think this applies to fear but the fact that their mouth is open. I've also noticed people cover their mouth when yawning and burping. People even chew food with their mouth closed. -- penubag  (talk) 17:56, 1 May 2009 (UTC)


 * Covering your mouth when yawning or burping is cultural, rather than instinctive. It's a social norm that has to be learnt. Parents will teach their children to cover their mouths when doing such things, they won't teach their children how to scream. I think covering your mouth when frightened is instinctive, rather than learnt, although I can't offer any real evidence for that. --Tango (talk) 18:12, 1 May 2009 (UTC)


 * An unlikely explanation: placing a hand in front of the mouth could stifle involuntary sounds in order to avoid alerting a threat. It sounds a little dumb to me (a simpler and more efficient instinct would be to simply shut up, after all), but I've heard it said. A more likely explanation: raising a hand up there protects the vulnerable face from a potential threat (and makes it easier to strike at an enemy, or block of an attack to the face), but leaving it a little low, at mouth level, doesn't obstruct the vision. Is that really the reason for the instinct? I don't know, but it sounds pretty reasonable.
 * Another, a little less primitive instinctual response could be to mask your emotions, either because open display of harsh emotions is something people are taught to avoid, or because spreading panic in a herd is not a good idea. This is, of course, pure speculation.


 * And as has already been stated, these instincts certainly don't apply only or even mostly to women. That's just silly: guys yell out when they're startled all the time, and the image in your example includes a guy doing the exact same thing as the woman. -- Captain Disdain (talk) 17:58, 1 May 2009 (UTC)


 * That's an interesting question. Screaming is a sensible reaction to something frightening, it's an alarm call that either warns other people of the danger or requests help from them. Plenty of animals have alarm calls. Why one would cover their mouth, though, I don't know... Thinking about it, covering the mouth is usually associated with a gasp rather than a scream, perhaps the hand is simply to prevent foreign objects from entering the mouth? (The gasp being an instinctive attempt to get air before doing whatever needs to be done - fight or flight, most likely.) I've never heard anyone say humans have only two instincts, but if somebody did then they are clearly wrong. There are all kinds of things humans do instinctively. Our major drives could all be considered instincts (sex, food, etc.). Our various reflex reactions (withdrawing a hand that comes into contact with something hot, for example). Even something like involuntary breathing could be considered an instinct. --Tango (talk) 18:12, 1 May 2009 (UTC)


 * Another human instinct that is hard to explain is being "petrified by fear". I used to think that was a figure of speech. But once when I was close to a caged wild animal it made the most terrifying snarl I have ever heard. I was so shocked I could not move or make a sound for about 3 seconds. That seems counter productive. If that animal had been free, it could have done me considerable harm while I could not move. Why do we become petrified by fear and unable to defend ourselves? It is an involuntary response, so I suppose it could be called instinctive. – GlowWorm.


 * As to the question by GlowWorm on "petrified by fear": I recently read about a Japanese study which indicates that "playing dead" (terms seem to be thanatosis and akinesis) are quite useful survival strategies amongst different species of prey.  More often than not the predator charges after those who flee in panic and ignore any individuals who have been petrified.  --Cookatoo.ergo.ZooM (talk) 20:24, 1 May 2009 (UTC)
 * It is far easier to spot movement than to spot a stationary object, so keeping very still, even when in the open, can be a good way of hiding. --Tango (talk) 21:08, 1 May 2009 (UTC)


 * This is a wild guess but I wonder if it (the hand in front of the mouth) is to prevent hyperventilation. When I imagine myself making that gesture, that's what it feels like I'm doing. I don't know why someone would do that rather than just slow their breathing, but people do hyperventilate, so who knows. -- BenRG (talk) 19:42, 1 May 2009 (UTC)
 * I'm not sure it would be very effective. You would have a significantly restrict the airflow, which I don't when I try and act it out (I restrict it a little, but I don't think enough to make a difference). --Tango (talk) 21:08, 1 May 2009 (UTC)


 * Some of the anthropoid species have fearsome-looking teeth which they show as a counter-threat when they feel fear. However, putting a paw in front of the mouth will hide the teeth. Perhaps that is an instinctive signal of non-aggressiveness. It counteracts the instinctive display of the teeth, and is thus an example of one instinct counteracting another instinct. A second thought, so to speak - or more precisely, a second instinct; it's not a matter of thought. Maybe that is why it seems to be done mainly by females – they tend to surrender rather than fight. This is far fetched, but I'll pass it along. – GlowWorm. —Preceding unsigned comment added by 98.17.33.211 (talk) 23:06, 1 May 2009 (UTC)


 * As for why it seems to you to be done mainly by females, perhaps cognitive bias would help. 80.41.85.182 (talk) 23:58, 1 May 2009 (UTC)


 * The scream reaction is demonstrated by every newborn baby. The next instinctual behaviour is to seek the comfort of pressing the mouth to mother's breast. These instinctive reactions re-emerge on occasions of stress. The hand pressed to the mouth substitutes for the breast in the same way as the thumb that a young child sucks or the cigarette that an adult sucks. Cuddlyable3 (talk) 13:19, 2 May 2009 (UTC)
 * Is that a guess or are you basing that on something? It sounds rather Freudian to me, and most of his theories have been debunked. --Tango (talk) 13:26, 2 May 2009 (UTC)


 * I'm surprised that people have left out these other possible reasons for the 'hand over mouth' reflex: 1) To hold the head up while in shock, 2) Bodylanguage that says literally "I'm speechless" or 3) self-comforting (again in a moment of shock). Personally I think this is related to 'shock'. People would do this to show that they are in shock. Thanks for the interesting question. Rfwoolf (talk) 02:16, 7 May 2009 (UTC)

Materials science
Is it possible to make a small homemade model plane or glider out of readily available materials that can carry a mass which is over 300 grams? Clover345 (talk) 17:40, 1 May 2009 (UTC)


 * Yes. --Jayron32. talk . contribs 18:02, 1 May 2009 (UTC)


 * Define "carry." How far, how high? I made one and threw it out the 2nd floor window and it carried the load straight down to the ground. Hard landing. Maybe a bigger wingspan was needed. Edison (talk) 18:16, 1 May 2009 (UTC)


 * Carried across about 10 metres launched from the 2nd floor of a building. As you said, any attempt just seems to fall straight down.  What material will actually do this?  Thanks. Clover345 (talk) 18:29, 1 May 2009 (UTC)


 * Does it have to strictly glide, or is it ok to attach a rubberband powered prop to the front? 65.121.141.34 (talk) 18:41, 1 May 2009 (UTC)


 * Ideally, I want it to glide. Are there any other materials other than Balsa wood which can do all of this? Clover345 (talk) 18:47, 1 May 2009 (UTC)


 * define "small". not knowing anything about the subject, i'd think something along the line of a hang-glider, where you could have a fairly large wing without much weight. if a big one can carry a person, i'd think a small one could carry 300 grams. Gzuckier (talk) 19:13, 1 May 2009 (UTC)


 * Sorry for being a bit vague. By small I mean about the size of an A2 sheet of paper(420 × 594).Clover345 (talk) 19:19, 1 May 2009 (UTC)


 * It is probably possible. If the cargo weight is 1/2 of the total weight, and your wings are 15mm wide and meet the maximum dimensions, your wing loading will be about 1/3 that of a Piper Cub airplane, so your structure could be about 40% as strong.  While the Piper Cub is not strictly a glider, it glides reasonably well in unpowered flight.  Now as a practical matter, you are going to have a lot of difficulty with stability, especially if you are using household materials.  For instance, how symmetrically can you make an airfoil shape with plastic wrap, glue and chopsticks?  This seems like a project that can be done, but will take a lot of time to get right.  65.121.141.34 (talk) 20:13, 1 May 2009 (UTC)


 * Maybe something inherently stiff and lightweight for the wing, like a piece of foam insulation panel, which is made rigid by the foil on each side. Does the wing have to be airfoil or would flat work? The keel could be the same material. It is the sort of thing that I might find laying around as a leftover building material. Alternatively, perhaps cardboard. Ordinary drawing paper seems too weak to have large wings supporting a heavy weight. You could get fancy and have support cables from various points on a paper wing to the keel, with stiffeners across the wing. A bit like building a bridge.  Edison (talk) 22:11, 1 May 2009 (UTC)


 * I may not be getting into the spirit of the thing, but if your aim is to get a reasonably soft landing 10m away from the building, I think throwing the object the 10m and making it a parachute might be more effective than a glider. --Tango (talk) 21:05, 1 May 2009 (UTC)


 * Placing the weight at the center of gravity of the plane is important. You should be able to balance the plane on your finger at the weight, if it's placed properly.  You also need enough speed to start with, to provide adequate lift.  Perhaps a slingshot mechanism could be used to launch the plane ? StuRat (talk) 22:21, 1 May 2009 (UTC)


 * For any given design, lift is proportional to the square of velocity, see airfoil. That means you can always keep something in the air by making it move fast enough.  If you have enough wing area to make the required velocity less than the terminal velocity of the object, it will "glide" to some degree.  The calculations are pretty complicated, but it looks to me like with a wing of that area, you need a velocity around 10 m/sec to get enough lift to counteract gravity.  In other words, you have to come pretty close to hurling the thing across the space, even with optimal design.  I'm not very confident of my arithmetic, though. Looie496 (talk) 02:00, 2 May 2009 (UTC)


 * I suspect keeping the plane from aiming straight down would be a problem. I'd suggest placing the weight on a rigid structure below the plane to balance it. Alternately, you could tilt the wing up in the back. — DanielLC 15:13, 2 May 2009 (UTC)


 * What about a small hot-air balloon with the wind in the right direction? I have never made one myself, but people used to make them out of very thin large plastic bags, such as a cheap rubbish/garbage bag. Or very light paper such as tissue or crepe paper could be used to make the balloon. They could have the air inside heated by putting them over a gas burner etc. Some designs have a flame of some sort (cotton wool soaked in something inflammable, small candle?) underneath them to keep them going. Note that these can be a hazard to aircraft and a fire hazard. Is the 300g a camera? You can get them lighter than that, including cheap digital ones that it might be possible to set to take photos every few seconds. You might be able to buy a steerable radio-controlled toy helium balloon - I seem to remember seeing them on tv. 89.243.185.122 (talk) 11:19, 4 May 2009 (UTC)

Please help identify the correct species of this butterfly
http://en.wikipedia.org/wiki/File:Common_Buckeye_Butterfly_in_Artis_Zoo.jpg —Preceding unsigned comment added by 117.197.146.20 (talk) 19:47, 1 May 2009 (UTC)


 * Common Buckeye redirects to Junonia coenia. --Cookatoo.ergo.ZooM (talk) 19:55, 1 May 2009 (UTC)

Looks like the owl butterfly, Caligo sp. to me. Not sure about the species, could be Caligo memnon. I'll try to look up the species and post it later. A less likely candidate is Eryphanis sp., but I don't think that's it. --Dr Dima (talk) 22:20, 1 May 2009 (UTC)

Please help identify the correct species of this bird / duck / egret - what ever it is!
http://en.wikipedia.org/wiki/File:Bird_in_artis_zoo.jpg —Preceding unsigned comment added by 117.197.146.20 (talk) 19:49, 1 May 2009 (UTC)


 * Looks like a stork to me. Could be a White Stork or an Oriental Stork --Cookatoo.ergo.ZooM (talk) 20:01, 1 May 2009 (UTC)


 * Indeed it does. Looie496 (talk) 20:06, 1 May 2009 (UTC)


 * It's a White Stork. The picture that Looie linked to is almost certainly a white stork, too, although the web page says "oriental stork" :) --Dr Dima (talk) 22:01, 1 May 2009 (UTC)

Alcohol (hand sanitizer, communion wine) and the flu
The Centers for Disease Control has said alcohol based hand sanitizers can prevent the spread of flu. The Alcohol rub article says they must be 60% alcohol to be effective. Is there some virus eliminating effect of alcohol in lower concentrations? For instance, if communicants at a church drink from a common chalice, and it is filled with Angelica communion wine(22% alcohol) does that in any way lessen the chances of a virus being transmitted from person to person compared to ordinary wine with 12% alcohol? This assumes that wiping the outside with a cloth does not eliminate virus transmission from contact of the mouth with the wine. (I would have said "killing the virus," but I have read on this page that scientists do not consider them to be "living.") Edison (talk) 21:54, 1 May 2009 (UTC)
 * In Chicago, the Roman Catholic church will not be using the common chalice. The "North American Old Catholic Church" forbids the common chalice with non-alcoholic wine, but allows it with 12% alcohol wine. Edison (talk) 00:17, 2 May 2009 (UTC)


 * The 60% is based on the level necessary to kill bacteria. The concentration needed to affect the virus will depend on the quirks of the virus.  Some viruses are not affected by alcohol at all, but as noted in a previous section the CDC does say that alcohol inactivates influenza, though I've yet to see anything about the concentration necessary.  I suspect though that most studies of this would have been done at bactericidal concentrations (>60% alcohol) so there may not be any studies of low concentrations like wine.  As noted, the Roman Catholic church is temporary suspending use of the common chalice to prevent transmission.  Dragons flight (talk) 00:33, 2 May 2009 (UTC)
 * Hmm, you'd hafta wonder why the alcohol content of the original host would matter, after it's been replaced by the blood of Christ. What is the Old Catholic position on transubstantiation? --Trovatore (talk) 22:13, 2 May 2009 (UTC)
 * Perhaps it acts as a Blood-borne disease after transubstantiation or consubstantiation. Edison (talk) 00:48, 3 May 2009 (UTC)
 * Well, with consubstantiation you could understand why the alcohol content might matter. But if it's transubstantiation, then the alcohol is gone, along with the rest of the wine, right?  So why should 12% wine be different from grape juice?
 * I'm sure the theologians are up to the task. They might say something like, well, we don't deny that the apparent properties of the elements (I think there's some technical name for this that I don't remember) remain, such as their taste and appearance.  So maybe virucidal activity is also one of these. --Trovatore (talk) 00:53, 3 May 2009 (UTC)
 * Oh yeah, accidents was the word I was looking for. --Trovatore (talk) 00:55, 3 May 2009 (UTC)
 * Yeah, I think if they accept that it tastes like wine, and not blood (I've tasted both, not easy to get them mixed up!), then they can easily accept that it gets you drunk in the same way as wine, and not blood. Perhaps Jesus was a raging alcoholic and had a blood alcohol content of 12%? (It's about 12 times higher than the highest anyone has ever been recorded to survive, but he was the son of God - there have to be some perks to the job, and a miraculous alcohol tolerance seems like a good one to me!) --Tango (talk) 14:57, 4 May 2009 (UTC)
 * I looked up transubstantiation; it's not quite what I thought. Actually it's quite brilliant.  Apparently the accidents remain the same, and are not an illusion.  So the wine remains wine, but only accidentally; it has become blood in essence.
 * Since killing viruses would seem to be an accidental property of wine (if wine does that), it's quite reasonable that the transubstantiated wine would continue to do it. --Trovatore (talk) 18:37, 4 May 2009 (UTC)