Wikipedia:Reference desk/Archives/Science/2010 June 13

= June 13 =

Flaming blood
First, is there any way that a substance could be produced which would cause a person’s blood to burst into flames? Second, if such a substance could exist, could it be contained in a pill form?--99.251.239.89 (talk) 02:52, 13 June 2010 (UTC)
 * There are substances that burst into flame on contact with water (which blood mostly is), but nothing that could actually cause the blood itself to burn. If you used something that burst into flame on contact with water, it would have to be injected - if swallowed, it would burst into flame somewhere in the digestive system. --Tango (talk) 02:56, 13 June 2010 (UTC)


 * Potentially you could have a pyrophoric (air reactive) material which would cause the blood to erupt in flames when it hits the oxygen in air (but not while it's still in the body). Most pyrophoric substances are water reactive too, though, and even those that aren't may react with the dissolved oxygen in the blood, or will be toxic even without bursting into flames. -- 174.24.195.56 (talk) 04:23, 13 June 2010 (UTC)
 * I think if you got such a substance to a high enough concentration for it to work, it would be toxic. --Tango (talk) 15:32, 13 June 2010 (UTC)


 * One suggested (but implausible) explanation for Spontaneous human combustion is a high blood alcohol concentration. Mitch Ames (talk) 12:33, 14 June 2010 (UTC)
 * One more plausible interpretation of many of those cases, however, is that high blood alcohol causes the victims to fall asleep while smoking. Blood alcohol concentrations of less than 1% are lethal.  There is just no way to get an aqueous 1% ethanol solution to ignite in air. TenOfAllTrades(talk) 12:47, 14 June 2010 (UTC)

No. "If such a substance could exist", we have no way of knowing whether it could be in pill form. Axl ¤  [Talk]  07:53, 15 June 2010 (UTC)


 * Well, blood is one way to make gelled gasoline, but it is used as a congealing agent. I lent out my main book on incendiaries so I'm not sure if I can help too much. Perhaps shotgun shells filled with something like pure sodium or magnesium? I'd think if it could survive being fired it would explode on contact with the water in the blood, which might be able to ignite something like thermite. I guess, now that I think about it, you'd want to have the outer bullet made out something like that, the thermite in the center, and the blood igniting the out coating which would start the thermite reaction. TheGoodLocust (talk) 00:56, 18 June 2010 (UTC)

Wouldn't humankind be capable of surviving an overacting solar flare after all?
At the end of this film, (apparently) everybody on Earth dies when a solar flare gets overactive enough to strike our planet. However, what if some people are in submarines? How deep underwater can this kind of solar flare cook anything? How thick would the submarine's walls need to be in order for everyone inside to withstand the onslaught, should a solar flare even be able to cook that far underwater in the first place?

Also, I think solar flares would only cook the daylight side of the planet. How long would this kind of solar flare stick around? Would it stick around long enough to cook the night side once it's morning for them?

Moreover, what of people who are currently underground - in subways, etc.? What of the people who got enough warning to get to a bomb/fallout shelter deep underground? How far underground would they have to be in order to stay safe?

If a handful of humankind could survive the Sumatra volcano 70,000 years ago, I'm sure we can survive rogue solar flares now. --Let Us Update Dusty Articles 03:28, 13 June 2010 (UTC)


 * The human race has been around for about 2 million years in its current form, during that time there have been plenty of large solar flares, yet we are still here. The Earth's magnetic field and atmosphere protect us. The film is complete fiction with no basis in reality (were the telepathic aliens that can predict the future not a give-away?). --Tango (talk) 03:48, 13 June 2010 (UTC)


 * Thanks, T. So if a solar flare as large as in the movie happened real soon, can you confirm whether we'd be able to protect ourselves by either diving deep underwater or running deep underground as described above? Or how else would we manage to survive this kind of solar flare, if you know of other ideas? --Let Us Update Dusty Articles 04:53, 13 June 2010 (UTC)


 * I suppose if the giant solar flare happened to coincide with the expected reversal of the Earth's magnetic field (sometime during the next few thousand years), then most of the mammals on Earth might be affected. There might be some extinctions, but it would be unlikely to include humans - there are just too many of us in too many different environments.  Science has little experience on which to base predictions, so we can only guess.  The flare at a time of very low magnetic field would have a drastic effect on civilization though.    D b f i r s   07:37, 13 June 2010 (UTC)

You need a nearby GRB to do significant damage, see e.g. here. Count Iblis (talk) 18:05, 13 June 2010 (UTC)

The most likely scenario for significant disruption of our high-tech civilization is for a solar flare to overload and destroy large numbers of power transformers at northerly and southerly locations. Because the manufacturing capacity for power transformers is limited, it would take a long time to replace the transformers. Jc3s5h (talk) 18:17, 13 June 2010 (UTC)


 * Also see Inconstant Moon by Larry Niven and its TV version Inconstant Moon (The Outer Limits). --Stephan Schulz (talk) 11:27, 14 June 2010 (UTC)

virus more active during rainy season?
I read in a newspaper editorial that virus infecting human beings become more powerful during the rainy season. Is there in truth in it?--117.204.90.213 (talk) 05:16, 13 June 2010 (UTC)


 * Viruses tend to spread more rapidly when humans are in closer contact (e.g. in winter in some countries), but I don't know of any evidence that rain affects the virus itself. Can anyone find any research?    D b f i r s   07:40, 13 June 2010 (UTC)
 * Not true, viruses are not lifeforms, they are just rather complex protein machinery. In winter, they are not changed structurally to appear any different to any other time of year, so there is no reason to believe a virus would become stronger in winter. However, weakened immune systems are at more risk of contracting diseases in cold, winter seasons. That's why a lot more people catch influenza over winter than at any other time of year, but it has nothing to do with the virus itself. Regards, --— Cyclonenim | Chat 10:24, 13 June 2010 (UTC)
 * When it comes to influenza, Influenza & Flu season deals with this somewhat. As with many things, the truth is we don't really understand that well why flus are seasonal. The greater close contact almost definitely plays a part (as Dbfirs has noted) but so could other things like the virus surviving on surfaces for longer (which may be partially due to changes in the viral structure from the different temperatures), dehydrated mucus and possibly a weakened immune system that Cyclonenim notes above. Lower vitamin D levels have also be proposed as a possible cause. One interesting thing is that while it's suggested a lower humidity may contribute, in tropical (& I think most subtropical ones) regions I suspect like wherever the OP is in India (Kerala?), the flu season tends to be the rainy months where some of the earlier mentioned factors would hold true or somewhat true but lower humidity generally wouldn't (although the humidity may always be fairly high so this could perhaps be why it's not a big factor). Our articles also discuss other potential factors like interaction with other diseases and school terms. As I've noted it's almost definitely a combination of factors but how much of contribution each one makes we obviously don't really know and potentially/probably? different ones in different regions. Nil Einne (talk) 13:07, 13 June 2010 (UTC)
 * Viruses and other infectious agents generally survive better in water than in dry air, and during the rainy season in hot climates there tend to be a lot of droplets of water floating around, as well as water on the ground that can be splashed. It makes a huge difference:  during the colonial era in tropical Africa, it was considered nearly suicidal to travel during the rainy season -- almost all the exploration was done during the dry season. Looie496 (talk) 16:59, 13 June 2010 (UTC)
 * Are you sure the exploration wasn't more to do with mosquitos? Nil Einne (talk) 01:04, 14 June 2010 (UTC)

Maximum/Minimum Irradiance..?
Maximum/Minimum Irradiance (solar constant) range for a "Human habitable" planet/planet-moon to have a habitable Global Annual Average Surface Temperature?

I am referring to a habitable planet for people, and not extremophiles.

I am referring to Global Annual Average Surface Temperature, as in 14°C for Earth,

and therefore don't mean Mercury's cold side, or Venus's upper atmosphere, or Pluto's core;

Pluto, Venus, Mercury, like planets could be habitable but are not in the Goldilocks Zone,

and I am only asking about heating by the parent star, which is the main factors, any other factors spinning things better can't be counted on like influence of the parent star itself. We may find "liquid water" near the core of Pluto, but the chances of people living there are nearly nil.

The solar contant for the Earth is 1366.08 Watts per Meter squared,

but that is for the semi-major axis (100%), but this value varies from 103.43% to 96.74%, and Venus' varies from 193.93%-191.30%-188.73%, and Mercury's from 1058.11%-667.69%-459.36%.

I am confident in what I am asking and don't need question improvement suggestions,

or other angles, tangents and sidetracks; If you think there is something wrong with the question, then you just don't understand it, and please don't bother.

Take for example a large moon of  COROT-9b : (exoplanet.eu)

Star Radius = 0.94 sol

Star Te = 5625 K

Stefan–Boltzmann constant, σ = 5.67051E-8

Semi-major axis = d, in this case 0.407 (± 0.005) AU

Eccentricity = e, in this case 0.11 (± 0.04)

=(((0.94*6.955e8)^2*(5.67051e-8)*(5625^4)) / (0.4069*149597870690)^2) /1366.0875

I used this example because Europe's CoRoT space telescope team has obviously lied to the journal Nature (3/10), reporting "CoRot-9b is circling its star in a "temperate" orbit.
 * Note that if the maximum is lowered then the minimum is raised.

Irrandiance Habitable Candidates?
This is not part of my question, just here for examples. Given the best possible conditions, (that is I not asking for an atmosphere that is so large that it would be warm past the orbit of Mars, but the pressure would crush a person, and that kind of nonsense.) what would be a stable range for irradiance for a "habitable for people" Global Annual Average Surface Temperature on an Earth-like planet or planet-moon; The range must be larger than Earth's 103.43% to 96.74%, less than Mercury's 1058.11%, and more than Mar's 36.06%, but what are the maximum and minimums?? 24.78.167.139 (talk) 05:26, 13 June 2010 (UTC)


 * You have obviously done a lot of research on this yourself, so you might be the best person to answer your own question. I must admit that I don't understand it because, as mentioned last time, so many other factors are relevant.    D b f i r s   07:43, 13 June 2010 (UTC)

250 and 430 K.
 * The papers cited in our Habitable_zone article might provide interesting reading, if you haven't already, to see what assumptions and models the authors used. As Dbfir says, you might be the most in-the-know person here about what you're after. Brammers (talk/c) 08:33, 13 June 2010 (UTC)
 * This is actually the first step to what I considered a more complex question, but it may be the other way around to answer this part, if I just plug in Albedo and Emissivity of the Earth, I could use a similar formula to calculate the Global Annual Average Surface temperatures of those same planets in the chart (or planet-moons there) but to make use of that angle of solving the problem I would then need to know what are realistic/stable Global Average Albedo's and realistic/stable Global Average Emissivity, Almost a catch 22. So, because of those suggestions I hunted down this MADSCI Question/Answer from long ago, because you may be right, I may have to go study cosmochemistry and geology to answer this question without anyone's help.  24.78.167.139 (talk) 09:53, 13 June 2010 (UTC)
 * I don't know why you are asking questions at the same time as saying "because Europe's CoRoT space telescope team has obviously lied to the journal Nature". Firstly accusations of lying in a scientific paper are very grave, perhaps you mean you believe they are mistaken in their results? Perhaps they mean something other than what you mean? Secondly you really need to show they are wrong before saying they are so why the questions about working it all out? Have you gone through their workings carefully? Dmcq (talk) 16:37, 13 June 2010 (UTC)
 * You have ignored the calculations above to make your comment; suggesting that such a planet is in the "habitable zone" is an ugly misrepresentation. 24.78.167.139 (talk) 06:27, 15 June 2010 (UTC)
 * The OP has asked variations on this question many times in the past. He or she seems unwilling to accept that there are huge uncertainties in the field of planetary science and extrasolar planet characterization.  It is not possible to put a boundary on irradiance for the habitable zone unless you explicitly state your assumptions.  Define habitable zone.  Define a suitable temperature range.  State your assumptions about the planetary parameters (albedo, atmospheric greenhouse effects, thermal re-emission, orbit parameters, and so on).  Once you have defined those notions, it will be trivial to give you a "percentage" for the stellar irradiance to yield a particular temperature range.  The biggest problem with your formulation is that you have jumped over these extremely critical problem definition stages and have started demanding numerical values.  This is equivalent to demanding "how much fuel would an airplane take?"  How can we answer such a question with a numerical value?  You haven't asked for anything.  We cannot give you a numerical value unless you specify your problem better.  Nimur (talk) 17:44, 13 June 2010 (UTC)
 * Nonsense, the "Goldilocks zone" is that simplistic. Also, your accusation is impotent to me as it was recommended to me that I keep asking 24.78.167.139 (talk) 06:27, 15 June 2010 (UTC)
 * Furthermore - regarding whether Deeg, Moutou, et al. "lied" in their paper: have you read the paper? Here it is: A transiting giant planet with a temperature between 250 K and 430 K.  I wonder how you can be more specific than that: they tell you right in the title - the error bars are so uncertain that the planet temperature might be too cold for liquid water, the right temperature for liquid water, or too hot for liquid water.  The error bars are so huge, that any possible scenario is plausible, based on available measurements and data analysis.  Regarding whether they characterize this as "temperate":
 * Its periastron distance of 0.36 astronomical units is by far the largest of all transiting planets, yielding a ‘temperate’ photospheric temperature estimated to be between
 * They even put "temperate" in quotation marks - to indicate that this is a hand-wavey term! But they actually told you the temperature ranges that they have deduced.  In science, we prefer quantitative analysis over vague terminology any day.  Nimur (talk) 22:10, 13 June 2010 (UTC)
 * You may be correct but I didn't expect to have access to the Nature article which I expect is by subscription, I was going by this quote misused to sensationalize the idea that the Na'vi are there waiting. It looks to me like the same crap that happened with Gliese 581 c, the the discovery team got their errors sensationalize as correct, and then two other teams had to write correct/contradicting papers saying it is out of not in the "habitable zone." Both cases are shameless. I think -23°C is a joke (and you blindly quote that), let alone the self contradicting loop that "Hot Ice" would be needed to have the needed albedo at that irradiance, I'm not so easily fooled these very unlikely contradictory ideas, it would much more likely be steam and a runaway greenhouse gas effect. 24.78.167.139 (talk) 06:27, 15 June 2010 (UTC)
 * I would also point out that many journals will allow intelligent and reasoned feedback on articles within a few months after they are published. (For Nature would probably be the correct way.) You can also contact the authors. However given the comments and questions you (24.78.167.139) left on the RD there's a good chance any feedback you have will be ignored. (Nature for example says "All contributions should be measured in tone, and should not contain inflammatory or otherwise intemperate language".) In particular, accusing the authors of lying is likely to get you automatically ignored which isn't surprising considering it's potentially defamatory (and this paper appears to include about 30 authors to boot). In other words beware the pitfalls befalling this infamous Conservapedia . But if you genuinely believe in your claims, consider writing a more reasoned and betterr worded response and submitting it rather then making claims to random people with no connection to the paper. In other words, put your money where your mouth is. If you have genuinely discovered a major error in the paper, I'm sure they'll be happy to know. Nil Einne (talk) 01:39, 14 June 2010 (UTC)
 * {| class="toccolours sortable" border=1 cellspacing=0 cellpadding=2 align=center style="text-align:center; border-collapse:collapse; margin-left: 0; margin-right: auto;"

! PIO ! Ecc. min. 0.07 ! Ecc. avg. 0.11 ! Ecc. max. 0.15
 * - bgcolor="#ffaa88"

Ha, ha, ha; if I have "genuinely discovered a major error," a child could do the algebra. Venus receives only 191.30% of the heat the Earth does, Mercury 459.36% minimum. I apologize if anyone thinks I was referring to extremophiles even thought I did add a disclaimer to the question. As I said above, I will likely have to create the answer to this question on my own as no one seems to have constructive scientific input to offer. 24.78.167.139 (talk) 06:27, 15 June 2010 (UTC) and true Venus at 191% of Earth's irradiance is not as important, but only to get an idea of how  663%  of Earth's irradiance is! ("Temperate," my gluteus maximus.) My not bothering to chop of sig.difs. doesn't disprove anything, which makes your comments rather petty; it's always the last desperate criticism of someone who has nothing worse, "ooooh, too many  sig.difs. it must wrong." If what you say was true at all you could have backed up what you say with some numbers of your own, but you have none I'm sure. If the quote above is even true, then -23°C is a lie. 24.78.167.139 (talk) 02:23, 17 June 2010 (UTC) and you will note that 0.01671123 is eight decimal places.24.78.167.139 (talk) 02:33, 17 June 2010 (UTC)
 * -bgcolor="#80b88f"
 * Periastron:     ||553.96%  || 604.88% ||663.15%
 * Semi-major axis:||479.12% || 479.12% ||479.12%
 * Apastron:       ||418.48%  || 388.87% ||362.29%
 * } $$ f=  (R^2\sigma T^4 ) / d^2\  $$
 * Apastron:       ||418.48%  || 388.87% ||362.29%
 * } $$ f=  (R^2\sigma T^4 ) / d^2\  $$
 * } $$ f=  (R^2\sigma T^4 ) / d^2\  $$
 * } $$ f=  (R^2\sigma T^4 ) / d^2\  $$
 * Considering if I understand your above messages correctly, you've accused the 30 or so authors of a scientific paper of lying without even having read the paper and instead going solely by a likely sensationalistic newspaper report yes it's hardly surprising you will have to do this on your own... I do await hearing the poor authors majorly embarassed and the major scandal involving Nature when it comes out this peer reviewed article contains a major error even a child could have noticed. Nil Einne (talk) 16:22, 15 June 2010 (UTC)
 * Not likely, the discovery team's paper for Gliese 581 c was left behind after the two other teams correct papers and hasn't been spoken of since except the qualifier in the article "it was first reported... (wrongly)." No one has retracted or apologized for that, and this will get swept under eventually in just the same way. The paper is obviously not worth reading if a child can prove it wrong. 24.78.167.139 (talk) 17:30, 15 June 2010 (UTC)
 * Children are taught not to use superfluous precision. Why do you have a chart with 3 or 4 decimal places on these values?  Have you conducted sensitivity analysis?  Can you provide error bounds, backed by data, to suggest that your work can sustain that level of precision?  Yet you keep repeating these values as if 191.30% of the Earth's irradiance level is an important result, or indeed that there is such a degree of accuracy in the definition of the habitable zone.  All the while, you seem to be missing the fact that the published results are not making such solid claims as you are - and then you accuse them of intentionally misrepresenting fact!  24.78, you are making serious accusations of scientific error, but you are providing us with little evidence of your own ability to understand and use standard scientific approaches.  Throwing equations and data at an anonymous group of volunteers on Wikipedia is not the same as a properly reasoned scientific process that is required for a journal like Nature.  The published numbers have been subject to scientific peer review.  That is why those journals and the results they present are notable.  There is room for error in science - peer review does not guarantee correctness - but it places a high degree of confidence that the claims can be backed up.  Nimur (talk) 15:22, 16 June 2010 (UTC)
 * -23°C is a lie,
 * Another desperate false criticism is saying I placed 3 or 4 decimal paces in the charts arbitrarily, when I actually used figures from scientific work already done; the Earths eccentricity can be found here http://en.wikipedia.org/wiki/Earth
 * - "If you think there is something wrong with the question, then you just don't understand it, and please don't bother." - 24.78.167.139 (talk) 02:33, 17 June 2010 (UTC)

is risk from smoking linear with amount smoked?
if person A smokes 1/5th as many cigarettes as person B, then is person A 1/5th as likely to get any health complications? (I read from the health effects of tobacco that it is "stochastic" (like a lottery) for many cancers, etc: either you get it or you don't.) 85.181.49.30 (talk) 09:27, 13 June 2010 (UTC)
 * I could be wrong, but I wouldn't imagine this is the case. For a cancer to occur, a complicated series of events needs to occur, a lot of things need to fail and you need to be quite unlucky. This is because you need genetic damage to be caused to cancer preventing genes and repair genes, AND THEN you need to have another situation where the gene which switches on and off cell division gets stuck on the 'on' switch. At this point, cell division becomes uncontrollable and you have yourself a tumor. But of course, there are any number of factors which can cause genetic damage and it's impossible to predict accurately for every day life. You can['t] predict which X-ray, gamma ray, carcinogen etc. which will directly cause the damage, so I'd believe it is indeed stochastic. Regards, --— Cyclonenim | Chat 10:29, 13 June 2010 (UTC)
 * Much like there is a concept of ED50 and LD50, when assertions are made about the association of tobacco consumption and cancer, it is merely a statistical significance that happens to be clinically significant as well. All posted data are averages.  That being said, how do you get 1/5 of a lung cancer?  It would also depend upon a potential carcinogenic plateau effect, and so percentages cannot be the only things stated (i.e. you'd have to provide absolute parameters as well).  Currently, though, smoking can be classified by "pack years", and so person A who smokes 1PPD x 4 years and person B who smokes 2PPD for 2 years are both said to have smoked for 4 pack years.  Do they necessarily match each other in terms of severity of risk?  You certainly bring up a good point.  DRosenbach  ( Talk 13:55, 13 June 2010 (UTC)


 * And again, it's worth emphasizing and reemphasizing the probabilistic nature of this. What these "risk" factors means is that out of a population of X number of people, Y number would be expected to have health complications. It doesn't really mean, "this individual has this particular chance of getting cancer"—cancer is not a rolling of dice. It also does not take into account the complexities of individual exposure—it cannot rule out all of the other variables involved. (For example, if you smoke and are exposed to high radon levels in your home, your chances of getting cancer are very high indeed, much higher than if you "just" smoke or if you "just" have high radon.) --Mr.98 (talk) 14:23, 13 June 2010 (UTC)
 * Let me guess - you're a smoker. 92.15.14.150 (talk) 20:04, 13 June 2010 (UTC)
 * Why would you assume that? I'm not a smoker, and I find it very irritating when people talk about smoking as leading inexorably to specific consequences for every person. Not only is it bad science and bad statistics, it's self-evidentally not true. If you misrepresent the risks of smoking as one set of consequences that happen to everyone, people only have to know one smoker who didn't experience those consequences to reject everything ever said about the dangers of smoking, since it was clearly not true. And most people know a smoker who didn't get lung cancer, for example. Far better to be honest about it. 86.164.69.239 (talk) 20:59, 13 June 2010 (UTC)
 * I'm not a smoker, and am quite against smoking. But that has nothing to do with whether I think people misunderstand the nature of probabilistic risk. I think that smoking is clearly a health problem without resorting to misunderstanding, and that such a misunderstanding leads to even more ridiculous pro-smoking positions like those outlined by 86.164. Truly "getting" what risk factor data actually means lets one actually make sensible choices and understand why anomalous results obviously exist (like the oft-cited grandparent who smoked every day and lived to age 95). --Mr.98 (talk) 21:57, 13 June 2010 (UTC)
 * Whilst I agree with 86 and Mr. 98, it's important not to overexagerate the risk of smoking, it's important to reinforce the idea that just because you might not get cancer, it doesn't mean you're going to live a good quality life. I'd venture to say that almost all life-long smokers are going to have inferior quality of life at some stage. They'll be less efficient at getting oxygen into their blood, so they're going to struggle more with exercise and even general living like climbing stairs (eventually). Not to mention the risk of COPD and other diseases. Cancer is a major effect of smoking, but not as common as respiratory distress. Regards, --— Cyclonenim | Chat 23:40, 13 June 2010 (UTC)
 * While they will almost certainly be less efficient at getting oxygen into their blood than they personally would otherwise have been, different people start from different positions, and have different reactions to the smoke, combining with other environmental effects. So, actually, there are going to be some people who smoke a pack a day for 60 years, and have no trouble climbing stairs. But there aren't going to be many of them, and there is currently no way for any individual to know whether they are going to be one of the tiny percentage who'll be okay, or whether they'll be like most people and experience respiratory distress. It really does matter (quite apart from being good science), because everyone has a "smoking athletic grandpa" story. 86.164.69.239 (talk) 19:45, 14 June 2010 (UTC)


 * I would expect that the curve of dose against cancer risk would be steep at first but then be less steep later. For example the increase in risk from shooting eleven rather than ten bullets at someone would be less than the increase in risk from firing 1 rather than zero bullets at someone. 92.15.14.150 (talk) 20:02, 13 June 2010 (UTC)


 * The British Doctors Study is the classic evidence for this. The study unequivocally proved the link between smoking and lung cancer, as well as several other diseases. This article shows that "carotid artery intima-media thickness [and therefore risk of stroke] increased with pack-years in both former and current smokers". However disease risk is not linearly associated with smoking; a "never-smoker" does not have zero risk of lung cancer. Axl  ¤  [Talk]  17:02, 15 June 2010 (UTC)

Side note
Above I've mentioned the risk of COPD and other lung diseases as a result of smoking. I wonder if smoking can cause a linear decrease in respiratory health, and are there any studies that show this? Regards, --— Cyclonenim | Chat 23:44, 13 June 2010 (UTC)


 * What do you mean by "a linear decrease in respiratory health"? Axl  ¤  [Talk]  07:57, 15 June 2010 (UTC)
 * Sorry, it was badly worded. Can smoking a certain number of cigarettes a day for a certain number of years be linked to a certain probability of having respiratory illnesses like COPD? Regards, --— Cyclonenim | Chat 17:06, 15 June 2010 (UTC)


 * Yes. Have a look at the British Doctors Study, in particular the "chart showing variation in mortality with amount smoked". Axl  ¤  [Talk]  17:26, 15 June 2010 (UTC)

Primary afferent axons
So according to the textbook there's a different thermal threshold for different primary afferent axons fibres. How does it actually work? I don't really understand it. -Tactile.ab (talk) 11:12, 13 June 2010 (UTC)
 * In the same way that you have no problem understanding how there can be a temperature threshold for any type of nerve fiber, why can't you extrapolate in your mind that different nerve fibers can have different temperature thresholds. I think that's simple enough, unless you had something more specific.  DRosenbach  ( Talk 13:47, 13 June 2010 (UTC)
 * It's a pretty complex question. The temperature dependence of action potentials is mainly a function of changes in the kinetics of voltage-gated sodium channels, but the point at which failure occurs is determined by the way these channels interact with other factors such as axon size and myelination.  The failure point is especially different between myelinated and unmyelinated axons, because of their different mechanisms of conduction.  The literature on this topic gets pretty technical, but if you are interested, here and an old paper that gives some of the basic phenomenology. Looie496 (talk) 16:40, 13 June 2010 (UTC)

Thanks! The link was quite helpful. -Tactile.ab (talk) 05:27, 14 June 2010 (UTC)

Ruth's Chris Steak House
They advertise that they cook their steaks at 1800°F -- firstly, what sort of oven are they using and secondly, I would think that such a high temperature would destroy the meat. Obviously it doesn't, but if anyone can explain, that would be great.  DRosenbach  ( Talk 13:45, 13 June 2010 (UTC)


 * Responding to the second question first, I'll ask you one of my own &mdash; if you put a roast in a 400°F oven, when do you take it out? (Hint: it's not when the entire roast is 400°F throughout, now is it?)  High external temperatures mean that you get some tasty, tasty chemistry going on at the surface of the meat (giving it that delightful 'sear', with all of its flavors and textures; depending on the meat, rubs, and glazes, there's going to be some combination of Maillard reaction, caramelization, and breakdown products of myoglobin).  You only want to do that for a limited time &mdash; a long, dry heat will suck all the moisture out of your cut of meat and leave you with leather.  Getting the sear (and the rest of the cooking) right is going to be a balancing act between time and cooking temperature.  TenOfAllTrades(talk) 14:06, 13 June 2010 (UTC)
 * (ec)This is the temperature of the outside of the steak (which will char) but obviously the middle will see nothing like this temp. You can get this kind of temp with a pottery kiln; presumably they just put the meat in and out of one for enough time to the centre to get to 120C or so. Not vastly different to a barbeque I would say--BozMo talk 14:09, 13 June 2010 (UTC)
 * I hope you meant 120°F, not 120°C &mdash; or I'm not ever coming to one of your barbecues! TenOfAllTrades(talk) 14:15, 13 June 2010 (UTC)
 * ... and I hope you really did mean 120°C or I wouldn't eat it!   D b f i r s   14:52, 13 June 2010 (UTC)
 * 120°C is way above water's boiling point &mdash; by the time the center reached that temperature, you would have driven off virtually all of the water from the meat. The inside would be leather, and the exterior would be burnt to a crisp.  The interior of a solid cut of meat should be relatively free of pathogens; presuming that it has been handled properly, the nasty stuff is generally on the outside.  (That's why it's important to cook ground beef all the way through, and one of the reasons why you shouldn't go impaling your raw steak with a meat fork &mdash; and why your prime rib roast only needs to be cooked to an internal temperature of 120-130°F for a nice medium-rare.) TenOfAllTrades(talk) 16:00, 13 June 2010 (UTC)
 * Wikipedia says you want the interior to reach about 160-165F (71-74C). I agree that 120C would destroy your dinner. --Tango (talk) 19:23, 13 June 2010 (UTC)
 * Our article has some bad cooking advice, then &mdash; and its numbers are different from those in the linked source (, purportedly based on USDA numbers). 160°F is a good target for ground beef, which as I noted should be cooked through to a higher temperature.  For a roast, pull it out of the oven at around 130°F to hit medium rare (give or take a few degrees, exact temperature recommendations will vary from one cookbook to another: ).  Let it rest, covered, for twenty minutes or so; the internal temperature will rise another 5-10°F as the outer layers come into thermal equilibrium with the core of the roast. TenOfAllTrades(talk) 20:04, 13 June 2010 (UTC)
 * The numbers are consistent with those in the source. The source is more detailed, so obviously the summary in the article won't be perfect, but it's about right. --Tango (talk) 20:52, 13 June 2010 (UTC)
 * Yes, 120°C would make a very tough meal, but the fat should prevent it turning to leather. I'd rather eat that than risk 120°F because I don't like "rare"! I'll compromise on somewhere mid-way between the extremes.   D b f i r s   20:57, 13 June 2010 (UTC)
 * FWIW yes I meant F not C. --BozMo talk 10:10, 14 June 2010 (UTC)
 * I'll go out on a limb here and suggest that even the exterior surface of the steak never really reaches 1800°F (though it certainly gets quite a bit hotter than the interior, and quite a bit too warm for comfort). If you put your hand in a hot oven, does your skin instantly reach 500°F? TenOfAllTrades(talk) 14:15, 13 June 2010 (UTC)
 * Cooking at 1800° would be like putting meat in a hot fire. It would even be hot enough to melt salt (almost). --Chemicalinterest (talk) 18:39, 13 June 2010 (UTC)
 * I hope they limit cooking time at that temp to a very short time just for a final sear, and cook the steak at a somewhat lower temp for the majority of the cooking time. Otherwise, your steak will end up black and blue (burnt on the outside, raw in the center).  Googlemeister (talk) 14:50, 14 June 2010 (UTC)

Allium Care
I grew a patch of allium this spring. They bloomed beautifully and are now green. Structurally they add to the architecture of the garden, but should I remove the heads and let the rest of the greens die back, as in tulips, or can I leave the heads as well as the greens to die back? So far they are sturdy and add to the garden in their green state as much as in their purple and white.

Barb —Preceding unsigned comment added by 75.72.20.144 (talk) 14:57, 13 June 2010 (UTC)


 * I can only say that I would leave the whole plant until it dies down naturally, because I find allium seed heads visually atractive. Why not experiment and leave some so you can see what they look like? If you don't like them you can cut them down. --TammyMoet (talk) 17:04, 13 June 2010 (UTC)


 * Hi Barb, I've got to say alliums are lovely. I had a rummage round to try to find a trusty source (since I'm not at home with Mum's big collection of thorough books by D. G. Hessayon) and the closest thing I could find is this guide from the UK's Telegraph newspaper. The gist is that if you don't want them spreading, just make sure to dead-head them before the seeds disperse, but until then you're fine. If you don't mind them spreading, you don't need to do anything. This seems to be the advice on other sites I could find too. Happy gardening, Brammers (talk/c) 19:52, 13 June 2010 (UTC)


 * According to Sarah Raven the fact the green is up for months before the flowers means you do not have to leave them to die back, you can cut the whole things down when the flowers die as they is already enough sugar stored in the bulbs by then. Certainly the green is starting to dry by full flower. We do cut back immediately but not for enough years to be absolutely sure of the advice. --BozMo talk 20:36, 15 June 2010 (UTC)

Dog whistles.
My new phone has a free App that simulates a dog whistle - the kind that is producing a short sound at a frequency higher than humans can hear - but within the range that dogs can hear. That much I understand.

But Scott (a black lab puppy - aged 6 months) has never been trained with a dog whistle...yet he reacts instantly and looks at me with head tilted to one side whenever I activate the thing. The software lets you set the frequency to all the way down to 80Hz - and if I whistle at 'normal' frequencies - one or two kilohertz - he totally ignores it.

Our article suggests that dog whistles can be used to inflict pain - but that seems hard to imagine at the pathetic volume that a cellphone speaker can produce (especially at what must be the upper limits it was designed to produce). Also, he doesn't seem to be distressed by this - his reaction seems more like puzzlement.

Why would Scott pay special attention to these very high pitched whistles and not the lower pitched stuff? Is there something out there in nature that his wolf ancestors evolved to react to?

SteveBaker (talk) 15:21, 13 June 2010 (UTC)


 * It may just be that it is unusual. He hears people whistling and phones ringing and other devices bleeping all the time and has learnt to ignore those because nothing interesting is associated with them. He probably hasn't heard a dog whistle before (since you say he hasn't been trained with one) so he is wondering what it is. --Tango (talk) 15:36, 13 June 2010 (UTC)


 * As to the pain I made an ultrasonic whistle once and was trying it out and couldn't hear a thing, but my mother came and complained about the noise and told me to stop it. Dmcq (talk) 16:06, 13 June 2010 (UTC)


 * That's unusual. Ability to hear high sounds usually diminishes with age - you should be able to hear it better than your mother. Of course, with only 2 people, the sample error is very high! (See The Mosquito for some more information.) --Tango (talk) 16:14, 13 June 2010 (UTC)
 * Yes I was quite surprised because I could hear bats okay so it must have been a quite high frequency. Dmcq (talk) 21:11, 14 June 2010 (UTC)


 * I don't think the answer to this is known, but it's interesting that rats and mice are known to emit ultrasonic vocalizations as distress calls -- that seems like something a dog might care about. Dogs also use high-pitched whines as distress calls, but they don't generally reach the ultrasonic range, so the relevance is unclear. Looie496 (talk) 16:51, 13 June 2010 (UTC)


 * Its thought that dogs evolved the ability of hear ultrasound for one of two reasons, according to Peters & Wozencraft, 1989; in Acoustic communication by fissiped carnivores. Pp. 14-56 in J. L. Gittleman, ed. Carnivore Behavior, Ecology, and Evolution, vol. 1. :
 * To detect the ultrasonic cries of prey species (such as rodents, as Looie496 notes)
 * Because newborn puppies communicate with their parents by ultrasonic vocalizations
 * In either case, you are probably hijacking instinctive neural circuits that your dog has tuned specifically to these wavelengths - which is why you are getting a behavioural response from him that regular whistles do not evoke. Whether your app might inflict distress is a matter of opinion, of course, but it might be worth noting that research facilities are very strict about the use of ultrasound within their animals houses. Largely because it could be distressful to rodent mothers who are caring for pups. Rockpock  e  t  17:11, 13 June 2010 (UTC)


 * I am curious (and skeptical) that the cell phone has either the electronics or the acoustic capability to create true "ultrasonic". Even a desktop PC usually has a 44.1 kHz sampling rate, permitting a maximum synthesis of 22.050 kHz.  But that's the software sampling rate.  The hardware digital to analog converter, especially on a mobile phone, may have an even reduced range.  The physical transducer inside the speaker might have a frequency response as poor as 5 or 10 kHz (these things are bargain-basement cheap devices).  It's plausible that if you have a high-end phone designed to play music, it might have a full audio capability up to 20 kHz - but even that isn't "ultrasonic," so how exactly is the device outputting a dog whistle tone?  (I suppose if the tone is at 19 kHz, you might hear a low volume or nothing; while the dog does hear everything; but that would be a "borderline" case - many humans can and do hear 19 or 22 kHz tones).  Nimur (talk) 18:03, 13 June 2010 (UTC)


 * Don't forget about harmonics. Ariel. (talk) 19:17, 13 June 2010 (UTC)


 * According to our article, dog whistles generally use frequencies in the range 16-22 KHz. Looie496 (talk) 19:23, 13 June 2010 (UTC)


 * Well, it works! Either I'm lying about not being able to hear it - or my dog is telepathic!  The software ("Dog Whistler" 1.2 for Android by Mobeezio) claims to produce sounds from 80Hz to 21.9kHz - with a default at 16kHz. Some people can hear 16kHz - others can't (I can't) - but even 21.9kHz works for my dog - and not may people can hear that. SteveBaker (talk) 00:46, 14 June 2010 (UTC)


 * I guess you might be irritating some humans, too - many can hear tones up to those frequencies! The Mosquito operates at 17 kHz, and claims that most adults don't hear it - but I've played around with audio and I know I'm able to pass a double-blind test at 19 kHz and higher.  Nimur (talk) 01:08, 14 June 2010 (UTC)


 * (EC) Actually most modern desktop PCs would support at least 48kHz (since it's used by most DVDs and many other digital video sources). And HD chips are getting rather common probably helped by things like Intel's HD Audio iniative meaning even cheap motherboards will often have a HD audio chip supporting at least 96 khz and probably 192 khz. Of course there is little benefit to humans from these high frequency ranges as ABX tests usually show. However the HD audio chips may be better in general. In terms of mobile phones, the teen buzz and similar rings tones (The Mosquito) have shown that many perhaps even most mobile phones are at a minimum capable of producing frequencies high enough that many adults can't hear them. (You can get different tones and test them and some fairly high frequencies seem to work but of course it's difficult to know what frequency the phone is actually producing without some sort of accurate recording/monitoring.) And these even seem to work with MP3 and I think AAC compressed versions tend to work although these aren't generally designed to keep such high frequencies well AFAIK. Bear in mind of course we aren't talking about accurate musical reproduction just some sort of noise sufficient for a listener to hear. (I tried it myself once on my cheap Panasonic VS2 and it did work, I did try a variety of frequencies up to about 21khz but I can't remember the cut off point where someone I tested it on was able to hear something, the lowest age was about ~21 so probably not the ideal test.) Nil Einne (talk) 01:22, 14 June 2010 (UTC)


 * As for cell phones not having sufficient volume, bear in mind that it takes far more energy to produce loud bass notes than treble, so cell phones are designed to produce lots of treble and very little bass. If this trend continues into the ultrasonic range, then a cell phone phone could produce a deafening ultrasonic sound without using up the battery quickly, if so designed. StuRat (talk) 17:13, 14 June 2010 (UTC)

Nuclear fusion physics and tokamak reactor design: from the ground up.
Assuming that a layman with 'high-school' level scientific knowledge wished to fully understand the complex physics underlying a tokamak fusion reactor, and had years in which to do so, what would be the essential building blocks of physics necessary to begin the long journey upward? An image that springs to mind is a pyramid of square blocks, each successive level allowing advance to the next. Another assumption (possibly mistaken) is that a full physics degree would involve units and modules not relevant to the specific subject of desired study. I emphasise that this is not a question regarding nuclear fusion itself, but rather an epistemological question about the long itinerary of subjects a student would have to follow to arrive at the final goal.

149.170.241.66 (talk) 19:08, 13 June 2010 (UTC)


 * To understand this stuff quantitatively, you will need a thorough base in electromagnetics, chemistry, plasma physics, atomic theory, and a healthy dose of nuclear physics. To support the quantitative understanding of these scientific concepts, you will also need several years' of mathematical theory beyond "high school" level - this typically means several courses in calculus and differential equations, a good level of linear algebra, and some fourier theory or complex analysis will help with the plasmas and the atomic theory.  Amazingly, this is what you will study if you obtain an undergraduate degree in physics.  (About the only other stuff required for a physics degree - material that would be "peripheral" to your fusion goal - would be one or two courses in "classical mechanics" - while not directly relevant to fusion, this knowledge and the associated techniques, like Hamiltonian mechanics, are essential to understanding the more sophisticated particle interaction theories that work at quantum scales).  If you want to further study fusion, you will probably continue with several graduate courses in plasmas, electromagnetics, and (finally), material specifically on nuclear fusion.  If you want to build Tokamaks, it will help to throw some engineering courses in the mix: a power electronics course, a few mechanical engineering courses (specifically, learning about vacuum systems); several engineering thermodynamics courses, and so on. Nimur (talk) 19:52, 13 June 2010 (UTC)


 * Nimur makes an good point in that an undergraduate degree in physics is very well suited to understand the fusion reactor. It's an interesting philosophical question if the physics degree is very well suited to all kinds of such projects, or if humanity is erecting only those constructions which can be conceived of and understood with a background in today's disciplines. Another epistemological question is what it means to know and understand the reactor. A typical answear to that would be "the ability to build it", in which case it becomes clear that no single person could "understand" the whole reactor. The material science involved in creating material that can withstand the heat and radiation is no less important than understanding the math of the chaotic plasma currents, the computer science needed to simulate and control it, the physics of fusion, or even a collection of so far unknown skills and knowledge, needed to tackle challenges in the construction which we are not yet aware of. With that in mind, your pyramid would be more like a branching tree. A trunk of undergraduate mathematics at the bottom, allowing access to branches to head off into areas of physics, mathematics, IT, engineering and other sciences.
 * EverGreg (talk) 12:04, 14 June 2010 (UTC) armchair philosopher
 * I would propose that physics is designed to be the systematic and quantitative analysis of any natural phenomenon. That is why, even though physics is conventionally taught to emphasize only a few subjects like "mechanics" and "electromagnetism", many prefixes exist to extend physics to the rest of the world: biophysics, chemical physics, space physics, material physics, semiconductor physics - physics is the set of systematic, mathematical approaches that are used to distill truth from controlled experimental observation.  It just so happens (for historical reasons) that when we train new students to think about the world in this quantitative way, we start by teaching them about parabolic trajectories and simple harmonic oscillators.  Those scenarios are simple example cases where the spherical cow approximation works for a much greater percentage of the time, and are thus suitable for beginners.  From the philosophical point of view, I firmly believe that there is no problem that is solvable by other techniques, but intractable using physics-style methods.  (I've gotten into some fierce debates with the soft science people, and especially those in the humanities, but I stand by my principles and have staked my career on them).  So, to reiterate: physics is systematic and quantitative: mathematics is crucial for the "quantitative" part; the systematic approach comes from a lot of training and experience working with smaller problems, and a good bit of intuition.  EverGreg's points are important: it's worrisome when our educational methods peg a person's skill-set, forcing them to merely extend prior knowledge and never to synthesize new knowledge.  At the same time, modern systems are so complex that they would be totally impossible to build or operate without specialization of labor.  I would consider "free thinking" to be a particular case of specialization of labor.  We need some "cogs" who are highly skilled and highly trained, but will never synthesize knowledge outside the disciplinary constructs that were forced on them by our educational and socioeconomic system. And, we need some "not-cogs" - people who are not bound by the constraints of the system - who will learn from our prior knowledge, but expand human pursuits to other areas.  (There's a good Asimov short story about this - the title eludes me - but they have accelerated the process of education with some sort of machine, bringing young children up to the point of advanced researchers within a few days.  On a few rare individuals, the machine totally breaks, and they can not learn anything from it - but these individuals, while forced to slowly and manually learn everything that their fellow students learned instantaneously, are the only people capable of inventing or designing anything).  Nimur (talk) 14:37, 14 June 2010 (UTC)
 * Profession by Isaac Asimov, 1957. 75.41.110.200 (talk) 20:01, 14 June 2010 (UTC)

formaldehyde
is formaldehyde a endocrine disruptor or reproductive toxin —Preceding unsigned comment added by Alexsmith44 (talk • contribs) 21:02, 13 June 2010 (UTC)
 * Formaldehyde isn't usually classed as a reproductive toxin, that is, is doesn't have any specific effects on the reproductive system. However it is both toxic and carcinogenic, so it could cause reproductive problems through either of those mechanisms. It's hard to give a firm answer on the question of endocrine disruption, because there isn't any agreed "test" or "standard" for an endocrine disruptor. However, it isn't the sort of compound that one would expect to be an endocrine disruptor, and I've never seen anyone suggest that this is a significant hazard for formaldehyde. Physchim62 (talk) 22:15, 13 June 2010 (UTC)

Body hair
I saw an advertisement saying that removing body hair in young people at puberty can prevent its regrowth later in life. How is this done? Why does it work? It is without the use of chemicals or lasers to kill the follicles, of course. 76.229.192.126 (talk) 20:45, 13 June 2010 (UTC)
 * Is this some new technology? None of the conventional methods would prevent regrowth without destroying the follicles.  Our article on Hair removal mentions lots of methods and includes some warnings.   D b f i r s   21:02, 13 June 2010 (UTC)
 * You can't prevent hair growth without destroying the follicles. They constantly produce hair, so if they're live cells then they'll continue to do so. All methods of permanent hair removal work on this principle: they destroy follicles. Regards, --— Cyclonenim | Chat 23:46, 13 June 2010 (UTC)
 * Rule VI of Life "Never believe anything you see, read or hear in an advertisement". Richard Avery (talk) 07:12, 14 June 2010 (UTC)

Ploughing a field with dogs
Has any culture ever used working dogs to pull a plough in a farming context (not a snow plough)? Just saw a sled being pulled by huskys on TV and I thought about this for some reason. Thanks. --95.148.105.80 (talk) 23:29, 13 June 2010 (UTC)
 * It's really not possible. Dogs aren't big or strong enough by a lot. See the image - and the difference is muscle volume.
 * 77.86.111.26 (talk) 23:44, 13 June 2010 (UTC)
 * The nearest thing is Dogcart (dog-drawn) 77.86.111.26 (talk) 23:48, 13 June 2010 (UTC)
 * It takes a lot more force to pull a plough through earth than to pull a sled across snow: a single human can pull a loaded sled across snow, but it takes a team of humans to pull a plough! Physchim62 (talk) 02:14, 14 June 2010 (UTC)


 * Dogs are not as strong as horses (or mules, or oxen) but neither are humans, which have pulled plows when stronger animals were not available, as in 19th century and earlier wartimes or periods when draft animals were not readily available . Multiple dogs would be required to exert the tractive effort of a draft animal. and small carnivores may be less efficient at pulling plows than large herbivores . Edison (talk) 04:46, 14 June 2010 (UTC)


 * ....and even a whole team of horses would get nowhere with a snow plough.--Shantavira|feed me 09:10, 14 June 2010 (UTC)
 * Why not? Cuddlyable3 (talk) 12:29, 14 June 2010 (UTC)
 * Have you ever tried fitting snow shoes onto a horse??!! Physchim62 (talk) 18:25, 14 June 2010 (UTC)
 * Unfortunately I can't include a thumbnail of this picture, and can only link to it. Looie496 (talk) 19:24, 14 June 2010 (UTC)