Wikipedia:Reference desk/Archives/Science/2010 September 4

= September 4 =

Snoring = Collapsed Trachea?
I've often seen in videos of riots or so forth that people who are assaulted and take severe blunt damage to their face/head start to make a very distinct and audible 'snoring' sound when they are down. They appear to be conscious (though sometimes barely) while doing this. I looked at various reasons why people snore and generally found an indication of a difficulty/blockage of the airway. Does anyone know what happened to them to cause this? I assume a collapsed trachea but I'm not particularly adept in anatomy or biology. Robots.by.hand (talk) 01:03, 4 September 2010 (UTC)


 * A truly collapsed trachea is a very serious event that's likely to lead to death without immediate intervention. I rather think you heard stridor due to someone being winded, a very unpleasant but hopefully very temporary event frequently caused by one's lungs being used as a dudelsack. -- Finlay McWalter ☻ Talk 01:25, 4 September 2010 (UTC)


 * The people I've seen in this condition did not sustain serious blows to their chest/stomach/back. And some of the people were fine after a short while (stood up/walked off after a paramedic/police officer instructed them to breath through in their nose and out through their mouth while they were on the ground for a few minutes in some videos) so it seems it wasn't a collapsed trachea. Robots.by.hand (talk) 01:42, 4 September 2010 (UTC)


 * My experience is that it's when I sleep in the wrong posture. Sleeping directly on the back or certain stuff where some flappy body organs do flappy things relaxed and causing the snoring.  Are you ready for IPv6? (talk) 07:29, 4 September 2010 (UTC)

World War III and Alein invasion
HOw likely is WWIII and alein invasion? Like is it for certain that WWWIII will never happen ever again and there won't be any more world wars? If it isn't and if WWWIII happens, will there be conscription reinforced in lots of countries where it's abolished? What about the US and selective service?

And how about alein invasion? If aleins do invade Earth and exterminate everyone how likely is it? What about meteors? Do people know when the next meteor will hit Earth. Lastly, will humans be extinct by the 25th century? Or sooner? HOw do people predict the Earth will be like in the 25th century.

I've read the above guidelines so don't say please that these questions ask for opinions. I'm not asking for opinions just to be clear. I'm asking for reliable sources or information that gives evidence for any of the above phenomena and past experience that could back up the occurence of the above phenomena.

thanks guys ... —Preceding unsigned comment added by 114.72.206.160 (talk) 08:33, 4 September 2010 (UTC)


 * You have asked five seven (by my count) separate questions above; at least one of them requires prediction of unforseeable future events, which the Reference Desks do not (and cannot) undertake. Trying to ask all of them under one heading will lead to confusion and unwieldiness: I suggest you repost your questions one at a time (waiting for each to be dealt with before posing the next one) so that each can be addressed (or not) separately. 87.81.230.195 (talk) 10:52, 4 September 2010 (UTC)


 * Unfortunately you won't get any reliable sources on the above phenomena. All we can give you are opinions, so here's mine.
 * "How likely is WWIII and alien invasion?" - We don't know. No one does, but I'd speculate that the former is more likely than the latter (given we've already have two!).
 * "Like is it for certain that WWWIII will never happen ever again and there won't be any more world wars?" - It is by no means certain that there won't be another World War. I'd say it's unlikely unless we get into another severe paranoia, power-bent struggle like the Cold War but we can't predict the future.
 * "If it isn't and if WWWIII happens, will there be conscription reinforced in lots of countries where it's abolished? What about the US and selective service?" - I'd say conscription is unlikely in Western countries, at least to the extent it was present back in World War I & II. Most warfare in modern technological countries is carried out almost in proxy with aircraft, ships and bombs. Of course troops are still necessary, but not to the same level as was required by trench warfare.
 * "If aleins do invade Earth and exterminate everyone how likely is it?" - If aliens invade Earth and exterminate everyone then obviously it's 100% likely. Sorry, I'll stop joking around, I know what you meant. How likely is it that aliens will invade our planet and kill everyone? Who knows. We're still trying to figure out whether aliens exist, let alone are they violent or peaceful. If they exist, they could be either.
 * "What about meteors? Do people know when the next meteor will hit Earth?" - Not for certain. Most meteor impact predictions are just that, predictions based on probabilities! I can't remember the specific examples off my head but there are predicted close-encounters in the near future, but none are predicted to be close enough to cause concern.
 * "Lastly, will humans be extinct by the 25th century? Or sooner? HOw do people predict the Earth will be like in the 25th century?" - Again, you're asking us to answer (with reliable sources?! ha!) a question which no one can know the answer to. It depends on too many factors. Do we stop climate change? Do we survive it even if we stopped emitting all ozone depleting gases now? Will a meteor actually hit Earth that we've missed? Will there be a global, nuclear war? It's impossible to predict. As for how people supposedly predict what life will be like in the 25th century: they're guessing. No one knows. We take predictions on technology by extrapolating how we've progressed/how we're progressing, but it's not very reliable in the long term. Regards, --— Cyclonenim | Chat 11:09, 4 September 2010 (UTC)


 * Our article on meteorites says that "an estimated 500 meteorites ranging in size from marbles to basketballs or larger do reach the surface each year" - so there will probably be one or two meteorite impacts somewhere on Earth in the next 24 hours. NASA has catalogued around 1,000 Potentially Hazardous Objects with diameters of 150m or larger which could potentially impact the Earth at some remote time in the future, but none has ever scored above 4 on the 10-point Torino Scale of impact hazard, and none currently scores above 2. Gandalf61 (talk) 12:41, 4 September 2010 (UTC)

poisoned letter
what is a poisoned letter like that that killed

http://en.wikipedia.org/wiki/Ibn_Al-Khattab —Preceding unsigned comment added by Tomjohnson357 (talk • contribs) 10:48, 4 September 2010 (UTC)
 * I don't think any details are available about that or about the many other reported cases of Chechen rebels being a poisoned by the FSB other than that in the more recent cases using food, the poison was slow acting.  Sean.hoyland  - talk 11:15, 4 September 2010 (UTC)
 * Whilst I doubt we can say for certain, it's likely to either be an airborne toxin contained within the envelope, such as anthrax, or a toxin coated on the letter that, when touched, is absorbed through the skin. Regards, --— Cyclonenim | Chat 11:50, 4 September 2010 (UTC)
 * Also, you may be interested in Laboratory 12.  Sean.hoyland  - talk 12:37, 4 September 2010 (UTC)
 * I found a FAS report which says "The Chechens claim that the agent coated a letter to Khattab with a fast-acting nerve agent, possibly sarin or a derivative."  A number of sources seem to agree at least that it was fast-acting.
 * What is so mysterious about the Russian poisonings is that usually they use some exotic element - thallium, polonium, mercury - something so obvious and undegradable that if you dug the corpse up ten thousand years from now you could still tell the victim was poisoned, and, in the case of the polonium, allowing the murder suspects to be tracked by their exposure. I don't know why a secret agency would use such unsecret tools, especially if they have something as devastating as a "contact nerve gas" in their arsenal. Wnt (talk) 17:22, 4 September 2010 (UTC)


 * With the case of the polonium, a lot of analysts saw it as a calling card. "We don't care if people know it was the Russians who did it," and so on (since access to polonium is pretty restricted). Who knows, though. --Mr.98 (talk) 19:08, 4 September 2010 (UTC)


 * Alexander Litvinenko poisoning describes what happened when the Russians poisoned someone with Polonium. It's pretty obvious that they wanted to be found out.  They were sending a message: "If you mess with us, we can kill you even if you think you're safe."  Polonium is only formed in few nuclear reactors in the world - the 'signature' of the isotopes formed made it a trivial exercise to figure which one it came from.  They must have realized that when picking such an exotic poison. SteveBaker (talk) 23:21, 4 September 2010 (UTC)


 * I can't find anything online linking the two, but I should add that the properties of this apparent contact nerve gas sound like what you might expect from the solid skin-absorbable dust described for the Novichok agent in a discussion here a week or so ago. Maybe this answers both questions... Wnt (talk) 21:53, 6 September 2010 (UTC)

Where does the ink from whiteboards go when you erase them?
This may sound like a silly question, but what happens to the ink when you clean a whiteboard (like this) with an eraser (like this)? I used to think it went into the eraser, but when I tried to clean mine, which must have been used hundreds of times, with water and soap, I noticed no ink would come out of it.

Does it pulverize and go into the air (ready to be inhaled), or does it somehow magically diffuse deeply into the eraser where it can't be washed out? Is it even real ink in those pens, or something else?

Thanks for your ideas, --Sven Eberhardt (talk) 13:00, 4 September 2010 (UTC)


 * From personal experience, the `ink' is not absorbed in to the eraser at all, the eraser just provides a source of friction. Flaky dust can settle into the tray at the bottom of the whiteboard if you have one, or disperse into the room. SemanticMantis (talk) 15:10, 4 September 2010 (UTC)


 * Yes, a thick layer of dust can accumulate under the whiteboard if it is not cleared up. A small amount might go into the air, but this is much less dangerous than chalk dust.    D b f i r s   16:29, 4 September 2010 (UTC)
 * Our whiteboard article is in horrible shape. The statement there that the inks are less toxic has been -tagged for ages. I know some professors with specific allergy/reaction to chalk, but in general calcium sulfate is pretty benign from a chemical standpoint. DMacks (talk) 06:26, 5 September 2010 (UTC)
 * Thanks for your replies. I find it hard to believe that pen ink is less toxic than chalk as well. But I didn't have any problems with either yet ;) --Sven Eberhardt (talk) 18:01, 5 September 2010 (UTC)
 * From experience, most ends up on your hands. -Atmoz (talk) 02:25, 5 September 2010 (UTC)

Looking at the sun
If someone looks at the sun with the naked eye on a clear day with no clouds, would it damage their eyes? I assume not...and no this isn't medical advice I don't intend to go out looking at the sun and besides it's cloudy.--92.251.223.71 (talk) 13:50, 4 September 2010 (UTC)


 * Looking directly at the sun is very likely to damage your eyes if done for any, even a short, length of time. Human eyes are not designed for that intensity of light. It is probably as stupid a thing to do as looking into a Laser It could very easily burn your retina. Do Not Do It! 220.101 talk\Contribs 14:10, 4 September 2010 (UTC)
 * See Solar retinopathy "Vision loss due to solar retinopathy is typically reversible, lasting for as short as one month to over one year." 220.101 talk\Contribs 14:15, 4 September 2010 (UTC)


 * See also this advice from NASA  Sp in ni ng  Spark  14:12, 4 September 2010 (UTC)
 * Eclipses are especially dangerous, because the pupil will dilate in response to the darkness, making damage more likely. See Solar eclipse.  I'm not saying it's safe to look at it any other time, but usually the brightness makes it very difficult to look at; the pupils contract, they eyes close, and there is a strong reflex to look away.  These responses are attenuated during an eclipse, making prolonged exposure (and thus possible damage) more likely. Buddy431 (talk) 14:54, 4 September 2010 (UTC)
 * As always, Wikipedia has an article on it..Sungazing --Aspro (talk) 14:15, 4 September 2010 (UTC)
 * But humans and their ancestors have been around for millions of years. Surely we would have evolved to tolerate looking at the sun? It would have been vital to look in the direction of the sun for hunter gatherer peoples stalking prey. If they could go blind that easily wouldn't they have died out? I know your eyes can be sunburned temporarily, but I can't imagine going blind. To take your wording 220.101, the human must be "designed to look at the sun", musn't it?--92.251.223.71 (talk) 14:19, 4 September 2010 (UTC)
 * Perhaps the ones that looked at the sun couldn't find a mate or were eaten by the prey they were stalking that avoided detection by having a blinding light behind them leaving only the ones that don't look at the sun.  Sean.hoyland  - talk 14:46, 4 September 2010 (UTC)


 * '92' I challenge your assertion "It would have been vital to look in the direction of the sun for hunter gatherer peoples stalking prey." If so, then the sun would be low in the sky and significantly less intense due to coming through a thicker section of atmosphere. People get cataracts, Pterygium (conjunctiva) and similar at least partly by exposure to sunlight. This link here to a PDF actually shows on (p.2) the damage caused by staring at a solar eclipse. Please read the references and links you have been given. N.b Your IP address indicates you are in Ireland, so the intensity of your light will be far less than where I am in Australia, but it is still a bad idea to stare at the sun! 220.101 talk\Contribs 14:50, 4 September 2010 (UTC)

This all depends on how long you look for, and it'd be pretty damn hard to stare at the sun long enough without instinct kicking in and making you look away. This is similar to trying to suffocate yourself by holding your breath. The sun is not magic; one quick look won't damage your eyes forever RECYCLED FIRE (talk) 15:02, 4 September 2010 (UTC)
 * It depends on a number of factors, not just how long. As I mentioned your local latitude is a factor, as is how high the sun is in the sky. But the fact remains (read the references supplied please!) that it is possible to cause damage to you eyesight by looking at the sun. 220.101 talk\Contribs 15:24, 4 September 2010 (UTC)
 * It's faulty reasoning to think your "instinct" or "reflex" would be good enough to keep you safe from harm. For example, if you touch a hot stove, your reflex will pull your hand back quickly - but you still may suffer a third degree burn!  The same applies for the eye - it is well known in optics labs that your blink reflex is too slow to prevent damage if a powerful laser shines in your eye.  The same caution is warranted with regard to the sun.  Do not trust your reflex to be fast enough to prevent permanent damage.  It is known from prior documented experience that your reflex will not be fast enough.  Nimur (talk) 16:37, 4 September 2010 (UTC)
 * Holding your breath is an incredibly poor example too. A better (but still far from perfect) example would be holding your head under water Nil Einne (talk) 16:45, 4 September 2010 (UTC)
 * A great deal of eye damage was suffered by early sextant users due to the design requiring the sailor to look directly at the sun.  Sp in ni ng  Spark  17:29, 4 September 2010 (UTC)
 * Looking at the diagram of one from that book, it shows a small telescope as part of the design. But where the naked eye is concerned, this is starting to sound a little silly.  The Sun just sits there in the middle of the sky - there's no way not to look at it now and then.  The article cites photochemical damage rather than a burn, but either way, I assume the retina takes time to cook - though I didn't quickly find data on short exposures.  And, in one of the most pathos-tinged experiments I've ever read of, it is apparent that staring at the sun for a full hour does not greatly reduce vision in the short term, though significant damage is apparent histologically.   Apparently sungazing can be used therapeutically, under bizarre circumstances.  Wnt (talk) 17:42, 4 September 2010 (UTC)
 * it shows a small telescope as part of the design, no it doesn't, the diagram I linked is a pre-1590 sextant. The telescope was invented in 1608 so not likely, try reading the text.  Anyway, my apologies, I must have got it completely wrong (along with NASA and the medical profession) it is perfectly safe to stare at the sun, do it as much as you want.  Sp in ni  ng  Spark  22:54, 4 September 2010 (UTC)
 * Sorry, Google is subjected to the "restricted page" thing, and apparently the two of us were issued different restricted pages and weren't looking at the same picture. Does it specifically say that pre-1600 sextant users were suffering permanent eye damage? Wnt (talk) 07:33, 6 September 2010 (UTC)
 * The navigator sighted along the staff and adjusted the crosspiece until one end of it was on the observed body and the other on the horizon. Because the sun was the body most commonly observed, longtime navigators inevitably suffered a considerable amount of eye damage.  The back-staff was invented in 1590 to counter the cross-staff's harmful effects.  Sp in ni  ng  Spark  19:15, 7 September 2010 (UTC)
 * That's a good find! If you can figure out how many times daily a navigator shot the sun, and how long he looked each time, and how much vision was lost, you'll have a quantitative measurement of the rate of damage from chronic exposure that's better than anything from the modern scientific literature. Wnt (talk) 16:26, 8 September 2010 (UTC)
 * The NASA article refers specifically to eclipses, which, as I explained above, have a number of factors that make them more dangerous than looking at the sun under normal circumstances. Surely staring at the sun, intentionally, can cause damage, sometimes permanent.  But as for unintentionally, briefly glancing at the sun, I think it's a lot less clear.  Maybe Nimur's right that our reflexes aren't fast enough to prevent damage, but the sun and a powerful laser are much different beasts.  I don't know the answer, but I tend to agree that a lot of the danger is over-hyped for incidental exposure.  People do look at the sun (sometimes intentionally, for long periods of time), and they don't just go blind.  There's damage, to be sure, but we're constantly wearing out our bodies, and in many cases, the damage is at least partially temporary (see Solar retinopathy).  It's also interesting that that article describes the damage as being photochemical, rather than thermal (where a laser generally causes thermal damage, if I'm not mistaken).  Buddy431 (talk) 00:43, 5 September 2010 (UTC)

Electric vehicles
When do you estimate that 50% of automobiles in Canada/US will be electric? —Preceding unsigned comment added by 76.68.167.110 (talk) 14:36, 4 September 2010 (UTC)


 * 2050, when the oil runs out. See Peak oil and Oil depletion. RECYCLED FIRE (talk) 14:59, 4 September 2010 (UTC)


 * That's very pessimistic! See this. --76.68.167.110 (talk) 15:25, 4 September 2010 (UTC)
 * There is a fundamental misunderstand of economics here. Oil will never run out. It will just get more expensive until alternatives become viable to develop. There is no need to worry. I think stuff like hydrogen is the most promising and would be more likely than electricty.--92.251.223.71 (talk) 18:08, 4 September 2010 (UTC)
 * The amount of petroleum on the earth is finite. There is a theoretical point where it would run out altogether, but as you say, by that time it will be so expensive to extract we will probably have stopped trying. thx1138 (talk) 16:37, 8 September 2010 (UTC)
 * There is a completely non-theoretical point at which it becomes profitable to manufacture oil. --Carnildo (talk) 01:37, 9 September 2010 (UTC)
 * Neither hydrogen nor electricity are source of energy - they are methods of distribution. See our article primary energy and our very thorough energy development article.  Nimur (talk) 18:48, 4 September 2010 (UTC)
 * We're talking about cars, not electricity generation.--92.251.213.233 (talk) 20:36, 4 September 2010 (UTC)
 * We can't answer this question. It's possible (for example) that the hydrogen economy takes off with hydrogen filling stations popping up all over the place.  If that happened then there might not ever be 50% of electric cars.  On the other hand, if the infrastructure for hydrogen doesn't happen and a political will to attack global warming seriously somehow kicks in - then it could probably happen in 10 to 20 years.  That "political will" thing is a tricky business.  One major disaster somewhere in the world that could be definitely attributed to climate change - or one Disney-style documentary about the plight of the cute baby Polar Bears - could take a hold of the public imagination and make it be so socially unacceptable to buy a non-green car that we'd flip over in about the time it takes cars to get too old to keep on the roads...10 years.  But it's unfounded speculation...and we don't do that here. SteveBaker (talk) 22:34, 4 September 2010 (UTC)


 * We dont speculate here.--88.104.91.225 (talk) 23:14, 4 September 2010 (UTC) —Preceding unsigned comment added by 88.104.92.244 (talk)
 * Predicting the future isn't always speculation. Since there are already electric cars lined up for market roll-out in 1-2 years (Nissan leaf), I'm not surprised if we have 50% electric cars by 2020. —Preceding unsigned comment added by 76.68.167.110 (talk) 00:49, 5 September 2010 (UTC)
 * To redirect this line of inquiry - are there reputable, freely-available market predictions from scholars or business analysts that predict electric car adoption rates over the next decade? These could be suitable and encyclopedic sources to base predictions on; they would be grounded in actual analytic process and data, instead of idle speculation.  Nimur (talk) 01:52, 5 September 2010 (UTC)
 * Do you mean electric motors powered by onboard gas generators? Because I think those will become more and more popular. But if you mean electric cars powered by the grid, I don't think they ever will reach 50%. If we run out of oil we'll make gasoline from coal, via the Fischer–Tropsch process. Hydrocarbons are likely to always be the power source for cars, hydrogen has too many problems to be likely. Ariel. (talk) 02:22, 5 September 2010 (UTC)

Wild plant with large purple snapdragon flowers, serrated leaf edge
About four or five feet high growing in damp streamside conditions in southern England. Non-woody stem. The purple snapdragon-like flowers were about an inch across. Does anyone know what it is please? It was not foxglove nor was it Rose Bay Willow Herb. Thanks 92.29.127.175 (talk) 17:53, 4 September 2010 (UTC)
 * Sounds like Himalayan Balsam to me. --TammyMoet (talk) 19:14, 4 September 2010 (UTC)

That's it, thanks. I had guessed that it was'nt a native British species. 92.29.116.238 (talk) 20:36, 4 September 2010 (UTC)

Forward-sweeping wings
Does anyone know of an aircraft with variable sweep wings that sweep forward? I am not talking about aircraft with wings that sweep forward to make a delta, like the Northrop Switchblade, I am talking about something that sweeps forward to make a wing like the Sukhoi Su-47 or the Grumman X-29. Thanks, --The High Fin Sperm Whale 18:55, 4 September 2010 (UTC)


 * Just from a quick read, I would think not. The forward-swept design increases performance but also increases torsional stress on the wings; since variable wing aircraft would naturally be structurally weaker than fixed-wing aircraft, such a design would be an engineering nightmare.  -- Ludwigs 2  02:00, 5 September 2010 (UTC)


 * Wouldn't the Northrop Switchblade then be an engineering nightmare? --The High Fin Sperm Whale 04:22, 5 September 2010 (UTC)


 * Not my field by a long shot, but since the plane exists, I'd guess not.   I was merely noting (well, opining, really) that the swept-forward design seems to put more stress on the inner joint of the wing - the articles on the two planes of that design say that more lift is generated by the inner part of the wing, and that the forward design tends to cause the wing to twist (which I am assuming means a rotation parallel to the plane of movement).  the variable wing design requires some kind of joint near the plane body (which is right where the extra stress develops in the wing forward design), and a movable joint is always going to be weaker than a rigid structure - hence the nightmare.  I'm not suggesting it's impossible, but the planes are already designed to within a fraction of the limits of the materials (the sukhoi article notes that the plane's top airspeed is limited by the materials).  but that's all an educated deduction - I'm willing to be corrected by someone more knowledgable on the subject.  -- Ludwigs 2  04:51, 5 September 2010 (UTC)


 * Apart from the Northrop Switchblade I don't know of any such aircraft. It is very likely there will be no such aircraft, for the following reason.  Variable-sweep is a  highly-specialised and expensive solution to a niche problem - namely the need to travel at high supersonic speeds at high altitude but also to have moderate takeoff and landing distances.  (The GD F-111 was originally conceived as a carrier-borne aircraft that could travel around Mach 2 at high altitude.  The variable sweep allowed both of these requirements to be met.)  Forward-sweep is a highly-specialised and expensive solution to a different problem - the need for high agility in combat.  No air force would attempt to solve both these problems with one aircraft design - if an air force did attempt to solve both with one design it would be a compromise and so would be vulnerable to enemy aircraft and missiles.


 * The high Mach number of variable sweep aircraft like the F-111 and F-14 seems not to be such a high priority now as it was forty years ago. The USAF no longer operates either of these aircraft types.  I think its only variable-sweep aircraft is the B-1 bomber.  The current generation of fighter aircraft have fixed-sweep, less sweep-back and lower wing loadings than their predecessors because less importance is placed on Mach number at altitude, and more importance is placed on rate of climb and maneuverability.


 * Forward sweep is better than aft sweep for reasons of aerodynamics, handling qualities and agility. That begs the question why weren't all the early supersonic aircraft equipped with swept-forward wings?  The answer is the nasty way in which swept-forward wings twist so that when they deflect tips upwards they also twist so the angle of attack increases.  Not nice!  However, with modern composite structures, which can be given different stiffness in one direction than at ninety degrees to that direction, it is possible to reduce or reverse the way in which swept-forward wings increase their angle of attack when they deflect their tips upwards.  So an aircraft with variable sweep and swept-forward wings would be a strange bird indeed.  People would look at it and say What is the designer trying to achieve?  Is he trying to design a high Mach number aircraft, or a highly agile combat aircraft?  The Switchblade is also intended to be a highly-specialised solution to a niche problem.  I don't know what its role is to be, but it certainly isn't simply to be very fast and/or very agile.  It is presently an experimental aircraft rather than one which has a clearly-defined role.  Dolphin  ( t ) 08:44, 5 September 2010 (UTC)
 * Another issue as to the paucity of forward sweep aircraft is that in most cases, the pilot is the limiting factor as to how maneuverable one should make an aircraft. It is all well and good if you can make an airplane that can perform a 20g turn, but if it kills or incapacitates your pilot, there really isn't much point to it.  With the advances in remote operated aircraft, there could very well be cause for a larger number of aircraft configured with forward sweep.  Googlemeister (talk) 14:50, 7 September 2010 (UTC)

radio
If someone talks about "breakthrough" when referring to radio equipment, what are they talking about? 82.44.55.25 (talk) 19:17, 4 September 2010 (UTC)


 * It's probably a generic jargon-y term to refer to finally getting signal out of static. This could be by changing signal parameters, moving the transmitter/receiver, aligning the antenna, and so on.  I don't think I've ever heard "breakthrough" in reference to a specific phenomenon.  Nimur (talk) 19:39, 4 September 2010 (UTC)


 * Adjacent-channel interference is a brakethrough of sorts. Can you give more info? --Aspro (talk) 20:35, 4 September 2010 (UTC)


 * Here is a Radio Ham thingy on brakthrough. It can include things like when  you set up a PA  system and the local cab company swamps your amp, so that you can here their calls and all.--Aspro (talk) 20:52, 4 September 2010 (UTC)

Thanks! 82.44.55.25 (talk) 22:16, 4 September 2010 (UTC)

raining oil
Is it possible for   a hurricane  too rain oil    thats on warm tropical oceans during hurricane  season or will it only  take  the   warm  water under the  oil. --86.41.140.251 (talk) 19:58, 4 September 2010 (UTC)
 * No. Even Popular Mechanics considers it unlikely, and that publication has a reputation for spreading sensationalized semi-truths to sell copy!  In reality, oil does not evaporate easily, (well, crude does contain a tiny quantity of light alkanes that could evaporate, but in small proportions); and the minuscule quantities that could get "dragged up" by wind and evaporation of water would be insignificant compared to other airborne pollutants.  Pollution can affect rainwater quality; but usually the relevant pollutants are particulate matter and gaseous pollutants like nitrous oxide, not heavy liquid hydrocarbons from an oil slick.  Nimur (talk) 20:03, 4 September 2010 (UTC)
 * Do you have a better source? It is not unlikely for evaporated paraffins to precipitate with rain, especially if they have had time to glom to dust.
 * "Small patches of non-evaporated oil and tar balls could be carried great distances by the currents and other smaller eddies, especially if strong winds are introduced during storm/hurricane situations."Accuweather.com
 * The answer to the question is clearly, "Yes." Why Other (talk) 22:07, 6 September 2010 (UTC)
 * Maybe, but quantities from dust-condensed vapor precipitating with rain will be very small and unlikely to cause the kind of sheen from road oils seen in videos that circulated after the Deepwater Horizon accident which probably prompted this question. Ginger Conspiracy (talk) 07:15, 7 September 2010 (UTC)


 * A large enough oil slick might kill a hurricane. Hurricanes depend on moisture evaporating from the ocean, and an oil slick prevents that from happening.
 * However our article on Weather_control, says that scientists now believe that a hurricane would churn the ocean so much that the oil wouldn't be able to prevent evaporation.
 * In either case, the oil will not evaporate and become part of the storm. APL (talk) 20:05, 4 September 2010 (UTC)
 * Do you have a citation for the assertion that an oil slick could kill a hurricane? Does it assume that storm swells would be shorter than the depth of the slick? Why Other (talk) 22:07, 6 September 2010 (UTC)


 * The National Hurricane Center published this document on what would occur if a hurricane were to strike an oil spill (specifically the Deepwater Horizon oil spill, but it could apply in most situations). Ks0stm (T•C•G) 20:23, 4 September 2010 (UTC)

tryn to find out what killed my mom in 1992
Aloha, I'm tryn to figure out what killed my mom at the age of 39. In 1992. She was healthy and worked for OSHA, drank a beer now and then but drug free and just liked to stay at home after work. On her death certificate it states the following: Cause of death~ Encephalopathy, probably from Hypoglycemia, due to Pulmonary Emboli, due to Cellulitis. I found her in her bed after looking for her for 2 days when she did not show up to work, medi vaced her to Providence in Anchorage,Alaska and she remained in a coma for 2 months after we decided to let go. She was breathing on her own. There was no autopsy done but my aunt told me that they took brain slices and came up with a Metabalical Catashpe, what ever that means~ I still don't know. For that matter my aunt could not be telling the truth because like i said there was no autopsy done.

I was 19 when i lost my mom and have been looking for answer ever since. we were best friends, and mother and daughter. I now have had my first daughter and know the feeling of love,from a mother to a daughter. This has been killing me for almost 20 years now and im telling my daughter stories of my mom and i cant tell her what exactly happened. She did have a cold at the time. Any help would be great on my mind and my soul~ Please email me @: @aol.co or @hawaiiantel.net (email addresses removed to discourage spam) I really appreciate all the helpful hints, mahalo for all the help! Jennifer L. Miller —Preceding unsigned comment added by Meandmonkey (talk • contribs) 20:10, 4 September 2010 (UTC)


 * I'm not so sure the reference desk is a good place for this question... Ks0stm (T•C•G) 20:20, 4 September 2010 (UTC)
 * Sorry to hear about your loss, but this is not the place to find the answer you want. I would add that doctors are generally very, very good at what they do, and autopsies are generally very, very accurate. The diagnosis on that death certification is quite specific and I would venture to trust the pathologist report. If you have more questions, these need to be addressed with those responsible for dealing with your mother. Sorry again for your loss. Regards, --— Cyclonenim | Chat 20:48, 4 September 2010 (UTC)
 * Um. I can't agree with the statement about doctors.  At the refdesk we don't give medical advice and tell people instead to see doctors, but that's because (1) we don't have enough information, (2) there's no quality control, and (3) we don't want to get sued.  (Not necessarily in that order.)  It's not because the doctors are necessarily reliable either; it's good to keep a healthy skepticism in their regard, and do your own inquiries if a doctor's advice seems off.
 * Jennifer, my sympathies. I can't say whether the death certificate is accurate or not.  But short of a full-scale forensic investigation, I can't imagine how you're going to get anything more reliable.  Maybe for your own peace, the best thing to do is accept the explanation given.  --Trovatore (talk) 21:00, 4 September 2010 (UTC)
 * Do you want to see encephalopathy, hypoglycemia, emboli, cellulitis? --Chemicalinterest (talk) 21:03, 4 September 2010 (UTC)
 * So you disagree that doctors are generally well trained and the most informed people to trust in this situation? Who else can give you a better answer, if not a pathologist? Regards, --— Cyclonenim | Chat 21:21, 4 September 2010 (UTC)
 * What I disagree with is the attitude of treating medical doctors like priests. The way to think of them is like mechanics.  Yes, your mechanic probably knows more than you do about how to fix your car.  Probably, though maybe not; it depends.
 * But in any case if you have a reason to think your mechanic has missed something, you mention it, right? It's your car that's at stake, not his.
 * As for there likely not being anyone available who can be trusted more than the pathologist, you might notice that I actually agreed with that in my response. But saying that a more reliable answer isn't available isn't the same thing as saying that that answer is very reliable. --Trovatore (talk) 22:59, 4 September 2010 (UTC)


 * (ec) Wikipedia has articles on encephalopathy, pulmonary embolism, hypoglycemia, and cellulitis, which you may find helpful. For a specific guidance in interpreting the death certificate, you should speak to a trusted medical professional &mdash; perhaps your own doctor.  At that point, if you have unanswered questions then you might consider approaching your mother's physician, the physician who cared for your mother in hospital, and (if necessary) the pathologist(s) who handled any tissue samples.  Bear in mind that it may take time to locate people and records, and that some of the physicians involved may have retired or even died in the last eighteen years.  TenOfAllTrades(talk) 21:06, 4 September 2010 (UTC)


 * (ec) Respecfully, I am the one who referred her here. This is not a request for medical advice per se; it's a request for an explanation, in lay terms, of what some of that stuff means.  For example, look at the post on her talk page -- it may be helpful if someone could explain what a "metabolic catastrophe" is, since we do not have an article on the topic.  Thanks, Antandrus  (talk) 21:10, 4 September 2010 (UTC)
 * A metabolic catastrophe is where the energy in demand by your body cannot be fulfilled by the supply. It's a very general term, though, and it's more of a symptom than a diagnosis. There are multiple causes. Regards, --— Cyclonenim | Chat 21:23, 4 September 2010 (UTC)


 * In layman's language, this would be something like Brain damage, probably due to low blood sugar, which was in turn a result of a blockage in the arteries of the lung caused by a skin ulceration. In other words, her brain did not get a sufficient amount of glucose, which caused a fatal amount of tissue damage.  The low blood glucose level was caused by a blood clot in the lungs, a clot which likely originated in a bad infection in her extremities (most likely a leg) and migrated to the lungs.  I'm no doctor, but was your mother diabetic?  hypoglycemia (low blood sugar) can result from insulin usage, and cellulitis is associated with diabetes.  -- Ludwigs 2  21:35, 4 September 2010 (UTC)


 * Assuming we can believe the death certificate - and I can see no reason to think it's wrong - then if what you are looking for is an explanation, then we should just look at what the words mean. We can't make a diagnosis - but we can take the diagnosis you have and tell you what the words mean.  You should probably read the articles yourself - but my quick reading suggests:


 * Cellulitis - an inflammation of connective tissue and skin. Cellulitis happens when bacteria that should normally be on the outside of the skin get inside.  There are a bunch of possible causes, the elderly, those with diabetes and those with compromised immune systems are at greater risk.  Open wounds, sores and such are a way for the bacteria to get where they shouldn't be.  This can cause all sorts of symptoms ranging from a simple rash to really nasty diseases of the "flesh eating" kind.


 * Hypoglycemia - Not enough sugar in the blood. It's implicated in cellulitis because diabetics and the elderly are prone to getting both conditions.  But laying in bed for days without food would also do that.  It sounds like a symptom rather than a cause.


 * Pulmonary embolism - A blood clot or some other solid lump (and embolus) formed somewhere in her body and came loose, flowing along a major artery and eventually lodging in one of the arteries in the lungs. Since oxygen is carried by that artery - suddenly there is a dramatic drop in the amount of oxygen in the blood.


 * Encephalopathy - Her brain stopped working - that happens when it's not getting enough oxygen and/or not enough sugar to power its metabolism. Clearly that is why she was in a coma - the rest of her body was functioning - but evidently her brain was too damaged to do anything more than keep heart and lungs functioning.


 * So the immediate causes are reasonably clear. The embolism presumably happened very quickly - days before you found her...probably while she was asleep.  Even if she was awake, this is one of the better ways to die.


 * My father died of a similar way - he was perfectly fine eating dinner, feeling OK...then he said he suddenly felt a bit 'woozy' and within 30 seconds fell off his chair and never regained consciousness. He was a heavy smoker - so his cause in his case was pretty obvious.  Presumably the embolism (in his case, a blood clot) cut off the oxygen to his brain - causing brief dizziness - then brain-death.  He was still breathing and his heart was still beating when the ambulance came - but he never showed any signs of consciousness - and within several hours he was finally pronounced dead.  But he didn't suffer, for him it was all over in seconds.  It's reasonable to assume that your mother didn't suffer either.


 * The hypoglycemia was to be expected if the body has been laying in bed with no food and the brain not functioning for days. Bedsores and pressure-point problems could have caused the cellulitis - but that hardly matters.  She was already dead.


 * Why did this happen? That's hard to tell without knowing a lot more about her lifestyle.


 * The question you perhaps should be asking is why the embolism formed in the first place. If she was a smoker or had some other issues to make her prone to this - then you probably need to look no further.  However, our embolism article lists a dozen kinds of embolism and perhaps three dozen possible reasons.  Some of them look like "just plain bad luck" things - others would be due to other injuries.  After all of these years have passed, you can probably only guess which of those things it was.  Read the article - see if any of the causes ring any bells.


 * What I think you should take away from this is that your mother's brain probably died very quickly, probably while she was asleep. All of the horrifying grief that you must have gone through after finding her is a terrible thing - but it's clear that she was effectively already dead.


 * SteveBaker (talk) 22:25, 4 September 2010 (UTC)

I'm no expert but it looks to me like the things listed there may be results of being in a coma for two months, lying in bed without moving. I would not necessarily take them as indications of what caused the coma in the first place. The most common cause by far of events like this is a stroke, but there really is no way of knowing without more information. Looie496 (talk) 01:15, 5 September 2010 (UTC)
 * I'm really sorry to hear about these issues you are having. I am only going to add that your aunt was talking about a metabolical catastrophe which is medical speak for her system being overwhelmed by a number of things going wrong. It is used in a number of different ways and needs to be understood in the circumstances in which it is used. Richard Avery (talk) 07:43, 5 September 2010 (UTC)

Okay, here goes... This my first, posting, editing etc on wiki, so there are bound to be a lot of mistakes. sorry. Sorry to hear about your mom. I think her death must have really devastating for you (guessing from the fact that it has been 5 years and you now have children of your own. I graduated in medical science 10 years back, but i grew up and still reside in an obscure state in India, a 3rd world country, as it is known. Getting back on track - you did not give a lot of information that could have helped. From what i analyse the important information answers only lead to more questions: 1. OSHA, i take it pertains to Occupational Health etc, so if your mom was working for the OSHA, Alaska, it is likely that she would have been diagnosed as Diabetic. But you made no mention of her having diabetes. 2. People do not go into a Hypoglycemic Shock or coma even if they are diabetic (many of the drugs like Insulin and OHA or Oral hypoglycemic agents used to control the disease/bring down the blood sugar will result in hypoglycemia). The body stores excess glucose as glycogen that can be converted back to glucose as and when needed by the body The human body also has a warning system that tells a person that his blood sugar is below the normal threshold. Most of us start shivering with excessive sweating and palpitation etc. when the blood sugar is ~ 60 to 70 mg/100ml. 3. Pulmonary embolism, in most cases does not lead to loss of consciousness nor does cellulitis, not over several hours anyway. 4, Encephalopathy takes several days to manifest as coma, and the causes are varied (liver failure being common) My apologies, but i just don't accept the cause of death (even if i am from an overpopulated 3rd world country) A more plausible explanation would be a stroke/CVA (cardiovascular accident). It may have been hemorrhagic or embolic, whichever the case, it often is life threatening without immediate intervention (hours not days). A CAT scan or MRI, if done will confirm the case. Again my sympathies, and sorry about the mess (my reply, i mean) Ralte, 6th September 0130 hrs IST  —Preceding unsigned comment added by Ralte (talk • contribs) 21:14, 5 September 2010 (UTC)


 * I agree with Steve Baker's answer above. Any comorbid infection during a cold could cause a blood clot and and embolism if it inflamed an artery, and it was a bad embolism near the brain so she probably went very quick from painless hypoxia to the brain. If it had hurt she probably would have been able to get out of bed and would have been much more likely to have been found by a telephone or a door.  Please rest assured that she probably had no idea she was dying, and that such freak accidents only happen to a small percentage of the population.  Most of us have much more painful cancers and heart disease to look forward to, where we will be very aware of a sense of impending death.  You might try explaining to your daughter that your mom was just very lucky.
 * Working for OSHA is unlikely to have any bearing on diabetes. Why Other (talk) 22:21, 6 September 2010 (UTC)

Distance required to see planet Earth from space?
In most reports or photographs from space, I have seen only parts of our planet. What distance is required to view our planet as a complete sphere? With Earth's diameter of ca. 12750 km, can that required distance be calculated mathematically? Thanks. —Preceding unsigned comment added by 66.183.191.95 (talk) 22:44, 4 September 2010 (UTC)


 * Well you could get the whole Earth in the picture from any distance if you use a wide-angle lens of the right focal length. Photographers reckon that a 50mm lens on 35mm film gives an image similar to the image produced in the human eye.  Using that set-up 35mm/Earth diameter = 50mm/distance, or a distance of 1.4 Earth diameters or about 11,000 miles.  Sp in ni  ng  Spark  23:04, 4 September 2010 (UTC)


 * Strictly speaking the required distance is infinite. From your eye or camera (for simplicity reduced to a point, but you need an eye at least as large as the Earth in order for the distance not being infinite) you can calculate the cone which has your eye at the tip and touches the Earth - the diameter of the circle where it touches the Earth is (diameter of Earth)*Sqrt(1 - (radius of Earth)2/(distance from Earth's center)2), if Earth is a sphere.
 * Icek (talk) 23:46, 4 September 2010 (UTC)
 * I think the question is really "how far away do I have to be such that Earth looks like a circle", which, as Spinningspark pointed out, is pretty meaningless if we allow any type of lens. It would be really cool to see a picture taken from, say, a balloon pointed straight down with a wide enough lens to capture the whole horizon.  I suppose you'd need a lens that could capture over 180 field of view, but such lenses certainly exist. Buddy431 (talk) 00:30, 5 September 2010 (UTC)
 * Yes, Imax has indeed produced such shots. Re Icek, I don't understand your point, you seem to be saying that one has to stand at infinity to see the full diameter of the earth - true, but you will still only be seeing half the earth, the opposite side is obscured.  If you are reading "complete sphere" to mean the entire surface area is visible then your answer should have been "it can't be done".  However, as Buddy431 pointed out, the meaning of the question is that the whole earth is in frame, not the whole earth is visisble.  Sp in ni  ng  Spark  00:50, 5 September 2010 (UTC)
 * Maybe I can rephrase the original question - how far do you need to be to see the (or an entire) equator? Ariel. (talk) 02:37, 5 September 2010 (UTC)
 * You'd have to be infinitely far away. (See my more complete answer below) SteveBaker (talk) 22:21, 5 September 2010 (UTC)

Assume the Earth has radius r and that your field of view is θ. Also assume that your field of view is a perfect cone and the Earth is a perfect sphere. In a two-dimensional space your field of view can be thought of as two rays secant to the circle of the Earth. So you are looking for the distance from you (the point from which both rays originate) and the center (or alternately, the point on the circle perpendicular to the line connecting it and you) where your field of view is greater than the radius of the Earth. I think. My calculations are probably wrong at this hour, but I came up with any distance greater than tan(θ/2)/{r cos(θ/2)) + (r - r sin(θ/2)) 76.199.167.204 (talk) 03:24, 5 September 2010 (UTC)

See: Horizon for the required height to get the horizon to the radius. Hcobb (talk) 03:33, 5 September 2010 (UTC)


 * Technically - these kinds of 360 degree photos: ...are photos of the entire planet - and they are circular (well, very approximately!) - but the deal is that because of perspective, seeing the entire world as a circular thing leaves most of it hidden. You aren't seeing a "hemisphere" - just a tiny circular patch that ends at the horizon.  The higher you get, the further away the horizon is - and the larger the circular patch that you can see becomes.


 * But mathematically, you never can see an entire hemisphere. You have to be infinitely far away from a sphere to be able to see that much.  The rays of light coming from the planet form a cone with it's apex at your eye.  Since the sides of the cone are never parallel - they always meet the sphere just a little short of the full hemisphere.  So if we're allowed to pick any lens - then at any height/distance at all, the earth can be pictured as an approximate circle...and there is no height (short of infinity) that'll let you see a full hemisphere.  So we can't answer your question without saying what "lens" or what "field of view" we're considering.  SteveBaker (talk) 16:02, 5 September 2010 (UTC)
 * I think Spinning Sparks first answer is pretty good. Consider this example which might clear the situation up a little. The astronauts on the space station. They can certainly see "the earth" against space from about 370km up if they look around, but it would be too big to see in "one go" and they are still only seeing to a particular "horizon" from their height. If they had a wide enough angle lens, they could easily take a photo of the "whole earth" against a background of space and stars but they would still only be seeing a fraction of the entire hemisphere facing them. As you get higher and higher you would see more and more of the planet until you go to a point where increasing your distance by a lot was only increasing your "view" by a little. One significant milestone for traveling away from the earth which might be worth describing is when the earth will take up 90 degrees of your field of view, (imagine looking forward and seeing one edge and then looking left and seeing the other edge) you would need to be about 2600km (1600mi) above the surface. I did this calculation just by drawing a circle then drawing a square where two of the sides are radius lines seperated by a right angle and the two other lines are tangents of those which cross at the last corner outside the circle. You the observer at the point outside the circle has a view of the earth described by the tangents. The distance to the center from opposing corners of this square is root 2 of the radius, so the section of distance that is NOT in the circle (between you and the circle) is root 2 of the radius minus one radius. Even at this point, you are only seeing "half" of the "half of the earth" that faces you.. So to see considerably more then 50% of the hemisphere facing you, you'd need to be considerably more then 2600km above the surface, 18000 km(11000mi)  doesn't sound unreasonable. Vespine (talk) 04:24, 6 September 2010 (UTC)
 * Technically, you shouldn't have to be infinitely far away on account of gravitational lensing effects from the mass of the Earth. I think. Wnt (talk) 16:32, 8 September 2010 (UTC)

Shorthand notations for nuclear decays
What is the shorthand notation for the alpha and beta decay? For fusion reactions it is aA(bB,xn)a+b-xC. Is there something similar for simple decays? Nergaal (talk) 23:09, 4 September 2010 (UTC)
 * You mean like 6Li(n,α)3H? Physchim62 (talk) 01:27, 5 September 2010 (UTC)
 * more like 5He(,α)1H with no trigger required, or 3H(,e)3He. But you can write 3H→e+-+3He. Graeme Bartlett (talk) 06:56, 5 September 2010 (UTC)
 * Sweet! Thanks guys! Nergaal (talk) 20:59, 5 September 2010 (UTC)