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October 9

Mucokinetics

The article on Mucokinetics says these drugs make mucus much easier for a patient to cough up (or I assume sneeze out). But what is done for patients who, due to injury or disease, are unable to cough up or sneeze ut mucus? Are there drugs that dissolve it so much they can easily swallow it?--178.167.189.6 (talk) 00:31, 9 October 2011 (UTC)

Normally, when you cough it up you do swallow it. You can't swallow it until you've got it out of your throat. The trachea (breathing tube) and oesophagus (eating tube) are only connected at the mouth. There are special massage techniques that can be used to move mucus up to the mouth. They are often used for people with cystic fibrosis. --Tango (talk) 01:17, 9 October 2011 (UTC)

Agree with Tango; I just want to add a link to mucociliary clearance, which I was taught to call the "mucociliary escalator". We normally swallow quite a bit of mucus, one of the reasons public spitting seems so unnecessary and selfish (no benefit, and some risk to others). -- Scray (talk) 03:20, 9 October 2011 (UTC)

Immune system strength

Is there any way or scale to measure immune system's strength (overall or against specific infections)? --178.182.107.62 (talk) 11:31, 9 October 2011 (UTC)

I am in no way an expert old chap, but I imagine there are two key criteria - one is the count of antibodies that are specific to the infective agent in question and second is the overall white blood cell count. The more antibodies the quicker they will latch on the infective agent and the more white blood cells the faster the agent will be attacked and destroyed. Quintessential British Gentleman (talk) 13:45, 9 October 2011 (UTC)

To measure reactivity against a specific antigen, the level of antibody activity is the most oftenly used parameter. If the response is primarily of the IgM isotype, it indicates that the infection may have taken place recently, if it is predominantly of the IgG isotype, it indicates that the response may be caused by an infection in the past. Some tests also measure cellular responses, such as the Mantoux test, which depends on T cell activity.

There is no simple way of presenting someone's "immune system's strength" as a number or anything like that. The immune system is complex, many things can go wrong, and it is when a patient has an abnormal frequency of infections, and especially of infections that are rarely seen in healthy people, that doctors will suspect that the individual has an immune deficiency. An incomple list of things to check:

• Immunoglobulin (IgG, IgA, IgM and IgE) levels. Some doctors would also like to test the IgG subtypes at this point (IgG1, IgG2, IgG3, IgG4).
• A blood count, to see whether the leves of lymphocytes, monocytes and granulocytes are normal.
• A test of specific lymphocyte subsets (CD3, CD19, CD4, CD8, various combinations with other markers).
• Measurement of complement levels and functional activity in both the classical, alternative, and Lectin complement activation pathway.
• Depending on symptoms, various functional defects might be suspected. In chronic granulomatous disease there is a functional defect in the granulocytes, which can be measured.
• Some lab's measure proliferative responses (mainly T cells) to antigens and mitogens, other's don't, and it is not universally agreed that this is a useful parameter.

I'm sure I've left something out. Check out the article Primary immunodeficiency, and its "diagnosis" section. --NorwegianBlue ^talk 21:31, 9 October 2011 (UTC)

Weight-guessing

This is supposedly a skill displayed at county fairs and so on, though I've never actually witnessed it. How does one go about guessing a person's weight based solely on visual clues? I think it would be an interesting skill to have. 198.228.193.194 (talk) 14:44, 9 October 2011 (UTC)

I don't see much use, unless at places like county fairs. For describing people, categories like round figure, skinny, etc would be more than enough. Quest09 (talk) 15:19, 9 October 2011 (UTC)

I've not heard of guessing the weight of people at fairs - usually it's guessing the weight of cake. If you wanted to guess the weight of a person, you could do pretty well by guessing their height and then making a rough estimate of their build and comparing those against memorised numbers (perhaps based on Body Mass Index - if you can get a reasonably close guess of someone's height and BMI, you can calculate their weight). One thing to be careful of is that there are two ways to be heavy for your height - lots of fat or lots of muscle (or, I suppose, lots of both, but that's rare). You need to allow for both. --Tango (talk) 15:24, 9 October 2011 (UTC)

"Weight guessers" basically give out cheap prizes if they are wrong <g> The idea is that they actually try to be accurate on men, but always guess low on women -- who rarely are unhappy. They are entertainers, not more. That said, they can be within 10% on men just by looking at height and face ... Cheers. Collect (talk) 15:54, 9 October 2011 (UTC)

Weight guessing seems like a very fundamental capability which would be of great importance for some animals. I bet if you ran fMRI you'd find a special part of the brain assigned to do it, which I bet is much enlarged in raptors that snatch up their prey in flight. But it's hard to search for this in the literature... Wnt (talk) 16:45, 9 October 2011 (UTC)

It's clearly important, but I don't think they are all that accurate at it. One of the standard pieces of advice if you are threatened by a large predator is to try to make yourself look bigger. If animals were good at estimating weight, that wouldn't work. Looie496 (talk) 18:36, 9 October 2011 (UTC)

Hmmm, but is the animal estimating weight there? I think an animal that projects power further into the environment - for example, a porcupine or a boxer with a long reach - is more dangerous despite equal mass. Wnt (talk) 01:30, 10 October 2011 (UTC)

Even if there were an evolutionary advantage, you can be sure that evolution wasn't using pounds (or kilograms) when it was invented. A weight guessing person would still need to train themselves to express their judgments in the units we use. Dragons flight (talk) 18:49, 9 October 2011 (UTC)

Of course I'm just speculating, but the amygdala contributes to the verbal or written expression of emotions in humans, not (in a narrow sense) an option in other animals. Wnt (talk) 01:30, 10 October 2011 (UTC)

Here's a brief NPR segment on weight guessers, It doesn't really go into specifics, but it does touch on the idea that the prizes are worth less than the price to play the game. [1]

APL (talk) 04:53, 10 October 2011 (UTC)

Integrity of the Cryogenically Preserved Brain

When a rich person has one of the various companies in existence nowadays cryogenically preserve their brain, is there any evidence that the currently most-widely-used procedures succeed at maintaining the brain's network of synapses and their associated activation thresholds? Peter Michner (talk) 17:14, 9 October 2011 (UTC)

Has anything subject to that type of "preservation" ever been reanimated? ←Baseball Bugs ^{What's up, Doc?} carrots→ 18:24, 9 October 2011 (UTC)

Yeah, frogs thaw out all the time naturally, but apparently large mammalian cells such as some connective tissue, spindle neurons and ova are subject to ice damage. Thawed mice remember how to run mazes, but the females are sterile and they all have substantially reduced lifespans. 64.134.157.164 (talk) 19:59, 9 October 2011 (UTC)

I don't see how there could be evidence, because currently we can't even come close to reactivating a brain that has been frozen -- far too much tissue damage. But in principle, nearly all the information ought still to be in there -- synapses are pretty large structures in molecular terms, and the receptor molecules that determine synapse activation thrshold ought to survive freezing pretty well. Looie496 (talk) 18:32, 9 October 2011 (UTC)

I suspect we can't even come close to reactivating the brain of a dead mammal in any case, whether or not it's been frozen (pace Mary Shelley). Tonywalton ^Talk 22:30, 9 October 2011 (UTC)

That would depend on your definition of death. If we use the old "heart has stopped" def, then plenty of people have been revived from death, brains included. StuRat (talk) 01:59, 10 October 2011 (UTC)

The question "does the technology to reactivate the brain currently exist?" is a different question than "is the information that is contained in the synapse network and the activation energy levels in each synapse preserved?" I don't pretend to think that the two factors alone in the latter question (which was the only question I was asking) are sufficient for retaining the information necessary to preserve a human mind, but I'd bet that those two things are necessary if it is at all possible. Peter Michner (talk) 22:58, 9 October 2011 (UTC)

I'm not sure that cryogenically preserved brains are any better than chemically preserved brains, as far as retaining the information in the brain. Has anyone ever compared the two ? I'd think that the risk of power failures (perhaps from the bankrupt company no longer paying the bill) over centuries would also be a major concern for cryogenically preserved brains. StuRat (talk) 02:03, 10 October 2011 (UTC)

What do you mean by chemical preservation? All humans who have been revived after hypothermic comas were not likely to have more than a little brain tissue frozen, and there was some brain damage for those who were partly frozen but the extent was varied and the effects weren't all permanent. I would have to review for information like long term memory loss. For extremities, we have frostbite which gives you some idea of the kind of damage to expect. 67.6.175.132 (talk) 19:14, 11 October 2011 (UTC)

I mean preserved in chemicals like formaldehyde. Obviously that will kill the cells, but if the goal is just to read the pattern of the brain cells and their connections, with some type of future scan, for the prupose of programming a computer brain to match, there's no reason the cells need to be alive. As for hypothermia, that's a long way from having your brain actually frozen solid. StuRat (talk) 17:19, 13 October 2011 (UTC)

arthritis

This question has been removed. Per the reference desk guidelines, the reference desk is not an appropriate place to request medical, legal or other professional advice, including any kind of medical diagnosis, prognosis, or treatment recommendations. For such advice, please see a qualified professional. If you don't believe this is such a request, please explain what you meant to ask, either here or on the Reference Desk's talk page.

This question has been removed. Per the reference desk guidelines, the reference desk is not an appropriate place to request medical, legal or other professional advice, including any kind of medical diagnosis or prognosis, or treatment recommendations. For such advice, please see a qualified professional. If you don't believe this is such a request, please explain what you meant to ask, either here or on the Reference Desk's talk page. --~~~~

→Στc. 19:33, 9 October 2011 (UTC)

Although, I don't think a healthcare professional would advice someone living in Florida to climb the Appalachian Mountains to get rid of his arthritis :) .Count Iblis (talk) 21:05, 9 October 2011 (UTC)

coin drop

I love this illustration so much.

if, say, we can dig a hole from north pole up to south pole, and drop a coin (or anything you would like to drop) in that hole, ignoring whats in earth's core, what will happen to the coin? — Preceding unsigned comment added by 203.112.82.128 (talk) 22:13, 9 October 2011 (UTC)

If you also ignore air drag, the coin will accelerate towards the center of the earth, overshoot and decelerate all the way to the oposite pole where it will poke it head (or tail) up and start falling again back to the original position. If you further assume a uniform density earth, the coin will be observed to follow a simple harmonic motion. --Dauto (talk) 22:29, 9 October 2011 (UTC)

(Edit conflict) If conditions were absolutely perfect, also assume there is a vacuum in the hole, the coin should accelerate to the centre of the earth. Whereupon reach the centre, it should undergo dampened occilation, before coming to a rest levitating at the centre of mass. Although conditions aren't perfect, which is to say that there is a variety of possible outcomes of how the experiment would fail. Like the centre of mass for the Earth does not remain in the same position over time, due to random fluctuations in density. Plasmic Physics (talk) 22:32, 9 October 2011 (UTC)

If you are assuming a vacuum, what causes the dampening? If the hole is full of air, then the coin will quickly reach terminal velocity, which for a coin is about 65 mph (according to Mythbusters). As it gets closer to the centre of the Earth, gravity will reduce (see shell theorem) and the density of the air will increase. That means the terminal velocity will reduce until it reaches zero at the centre. I'm not sure if the coin would slow down fast enough to avoid overshooting, but I wouldn't expect it to overshoot by much. --Tango (talk) 23:36, 9 October 2011 (UTC)

Dampening is caused is caused by a loss of momentum. Kinetic energy of the coin is converted to gravitational potential energy and as it overshoots the centre of mass. It is the same reason why a rubber ball bounces lower on each rebound. Plasmic Physics (talk) 00:02, 10 October 2011 (UTC)

Dampening occurs with your rubber ball due to inelastic collisions. Without losses to air resistance (or eddy currents) the gravity train acts more like a (magical) perfectly elastic superball which would keep on bouncing for ever. -- 49.230.105.185 (talk) 00:30, 10 October 2011 (UTC)

Other factors might cause dampening to occur: electromagnetically-induced currents in the surrounding material, transfer of gravitational momentum, vacuum energy pressures, etc. ~AH1 ^(discuss!) 01:08, 10 October 2011 (UTC)

Why would the air density increase? Tonywalton ^Talk 00:03, 10 October 2011 (UTC)

The immense gravity at that depth would squeeze any air to a very high pressure, and additionally heat it to above the boiling point of water, unless a near-vacuum is created. ~AH1 ^(discuss!) 01:08, 10 October 2011 (UTC)

Immense pressures, yes, but note that the greatest gravity occurs at the surface. -- 49.230.105.185 (talk) 01:38, 10 October 2011 (UTC)

(E.C.) Air pressure varies with elevation. The radius of the earth is significantly greater than the height of the substantial atmosphere, so it would seem that the air deep in the tunnel should liquify, but the critical point of nitrogen is 3.3978 MPa or only 34 bar (with T_cr = 126.19 K). With atmospheric pressure increasing by 0.5 bar in the last 6 km above sea level, 34 bar would be reached well before a depth of 34 bar * 0.5 bar / 6 km = 408 km (with the effect of the ever increasing heavier layers of air overhead greatly overwhelming the slight decrease in gravitation acceleration). From there on down the nitrogen would be a supercritical fluid. -- 49.230.105.185 (talk) 01:31, 10 October 2011 (UTC)

You might find the Gravity train article interesting. Tonywalton ^Talk 22:34, 9 October 2011 (UTC)

That article is missing an important piece of information: the maximum gravitational acceleration (it is different when the accelerated object is inside another object of mass that is exerting the gravity) assuming an infinite terminal velocity. For humans, determine whether an average body can survive the acceleration. ~AH1 ^(discuss!) 01:08, 10 October 2011 (UTC)

I'm not sure what you are implying here, AH1, but per the shell theorem (and square / cube considerations), the maximum gravitational acceleration will occur at the surface, and will decrease linearly to zero at the center. -- 49.230.105.185 (talk) 04:49, 10 October 2011 (UTC)

what would happen if i threw my mother-in-law in the hole? =D — Preceding unsigned comment added by 203.112.82.1 (talk) 23:51, 9 October 2011 (UTC)

You are describing a "gravity train" scenario. However, heat and atmospheric pressure/liquidity considerations are important. ~AH1 ^(discuss!) 01:08, 10 October 2011 (UTC)

In case there is air in that tunnel, the immense heat and pressures would likely slow down the coin as it spun around its own axis in the air, and very quickly vaporize. If vacuum engineering and other considerations fail to anticipate the launched object (or person!) arriving short of the surface target, retrieving the launchee may be a problem.

A question - in the case of a magnetically-levitated train, would any effects occur upon interaction with the Earth's polar magnet, and even considering a non-magnetic vacuum train: how does one ensure that the projectile does not hit the side of the tube, whatever material it is constructed of, and instantly vaporize? ~AH1 ^(discuss!) 01:08, 10 October 2011 (UTC)

Dampening is occuring to momentum being converted to waste heat. Work is done on the coin to draw it towards the centre of mass. As we all know, no thermodynamic process is perfect. Plasmic Physics (talk) 01:43, 10 October 2011 (UTC)

The whole atmosphere will be sucked into that tunnel. The pressure as a function of height is given by:

$P(x)=P(0)\exp \left(-{\frac {mMG}{2kTR^{3}}}x^{2}\right)$

where M is the mass of the Earth, m the average mass of an air molecule and R is the radius of the Earth. This is assuming constant temperature and validity of the ideal gas law. It follows from this that the total mass of air in the tunnel is given by:

$M_{t}={\sqrt {\frac {2\pi mR^{3}}{MGkT}}}\exp \left({\frac {mMG}{2kTR}}\right)P_{\text{at}}A_{t}$

where $P_{\text{at}}$ is the atmospheric pressure at the surface and $A_{t}$ is the cross sectional area of the tunnel. The total mass of the atmosphere times g equals the atmospheric pressure times 4 pi R^2. Before we build the tunnel, the atmospheric pressure is 1 bar, and that gives a total mass of about

$M_{\text{at}}=5.28*10^{18}{\text{ kg}}$

Then after the tunnel is completed, air will flow into the tunnel until the above formula for $M_{t}$ becomes consistent with an atmospheric pressure of $(M_{\text{at}}-M_{t})g/(4\pi R^{2})$ For a cross section of 1 m^2, this leads to an atmospheric pressure of about 10^(-151) bar. Count Iblis (talk) 04:12, 10 October 2011 (UTC)

Neither of your assumptions (isothermal and ideal gas law) seem reasonable to me. Dauto (talk) 04:39, 10 October 2011 (UTC)

They're not wrong by 150 orders of magnitude, though. You need to take into account what happens to all the matter you remove in order to create the hole, though - that will have the same volume as the air that replaces it. If you place it all on the surface, it will expand now it isn't under pressure and will take up quite a lot of space. I'm not quite sure what that would do to the atmospheric pressure, though. --Tango (talk) 11:37, 10 October 2011 (UTC)

Actually it is, once the pressure reaches the point that gas liquifies you aren't going to increase the density more than about 10 times beyond that. At that density less than 1 millionth of the atmosphere will actually fit in your 1 m^2 tunnel. Dragons flight (talk) 18:46, 10 October 2011 (UTC)

Yes, I agree that the estimate based on the ideal gas approximation is not appropriate. Count Iblis (talk) 14:49, 11 October 2011 (UTC)

Where can I see a pressure / density graph of super critical fluid nitrogen. Supercritical fluid#Phase diagram includes such a graph for CO₂ -- would one for N₂ be similarly shapes, albeit with different values? -- 110.49.225.244 (talk) 05:15, 11 October 2011 (UTC)

In any case, the coin should melt or even vaporize since the earth's core is thousands of degrees. Googlemeister (talk) 13:18, 10 October 2011 (UTC)

Well obviously the evacuated tunnel of unobtanium is cryogenically cooled. Dragons flight (talk) 18:35, 10 October 2011 (UTC)

How about Coriolis effect? I expect it will have an important role if the hole were through equator.--Almuhammedi (talk) 12:42, 12 October 2011 (UTC)

Sure. You're shooting an object through a tube that is also turning. If the tunnel is straight, the coin will hit the side. I'm not sure what path the coin would take if you cut the tunnel so that it wouldn't hit the side. The coin would be starting with pretty substantial angular momentum, so it would follow a sort of orbit, but the gravitational field inside the Earth is different than the familiar orbit setup. Rckrone (talk) 15:14, 12 October 2011 (UTC)

If we give the coin a fairly big (in two dimensions) cavity in which to maneuver, I think it should still describe an ellipse, based on the "simple harmonic motion" mentioned above. If r is the distance from the coin to the center, the force of gravity should be proportional to the mass within r (r^3), but diminish by r^2, thus gravity proportional to r. (Ignoring that the core is denser than the mantle) The difference is only that this ellipse has the center of the Earth at the center, whereas a Keplerian orbit has the center of the Earth at a focus! Seems like a lovely coincidence that surely must not be... Wnt (talk) 16:32, 12 October 2011 (UTC)

I once read a science fiction novel where this sort of thing was proposed, called a "bouncing orbit". It involved two masses joined above the north pole, falling straight down. At some point the two masses would electromagnetically repel each other, go around the Earth, and meet on the other side opposite the south pole (using magnetic repulsion to slow their approach and recharge the energy storage for the next separation). The center of mass would bounce up and down through the planet just as the picture of the coin above. The story's antagonist would hold the Earth hostage on every orbit, threatening to disable the separation phase if certain demands weren't met. I wish I could remember the title of that book. ~Amatulić (talk) 22:29, 13 October 2011 (UTC)

October 10

Lightning and auroras

Hi. I'd like to know more about the interaction of upper-atmospheric lightning and tropospheric-origin electrical discharges, including elves, sprites, jets, gamma-ray flashes and antimatter generation events, with the lower-ionospheric geomagnetic aurora activity, which can extend down to 35 km altitude. In particular, are there any effects of interaction, which could be rare since strong thunderstorms and auroras are differentiated by latitude, but do effects occur that either change the atmospheric composition or channel energy from the Earth's geomagnetic field and solar wind, including its ionizing radiation and magnetic anomalies, down to the Earth's surface through lightning discharge or other phenomena, including plasma radiation? Please also link to any relevant scientific journal articles, and in particular the information found in Schumann resonances may be relevant. Thanks. ~AH1 ^(discuss!) 00:46, 10 October 2011 (UTC)

Please correct me if I've missed your point, but are you asking for scientific information about how elves and sprites effect the weather and the aurora borealis? Beeblebrox (talk) 20:18, 10 October 2011 (UTC) Never mind, it appears these terms are actually used by science to describe u-a lightning events. How silly of them. Beeblebrox (talk) 20:20, 10 October 2011 (UTC)

The etymology is a tongue-in-cheek reference to the history of these events. When atmospheric scientists started reporting unexplainable bright flashes in the night sky, naturally everyone jumped to the UFO conclusion. It took several decades before scientific reports about sprites, jets, and elves, were taken seriously. Nimur (talk) 16:48, 11 October 2011 (UTC)

My understanding is that these sorsts of things are effects of lower level storms, not causes in themselves. See http://en.wikipedia.org/wiki/Upper-atmospheric_lightning#Elves to begin with. Let us know if you have more questions. μηδείς (talk) 07:15, 11 October 2011 (UTC)

Here is a listing of textbooks from some of the world's preeminent experts on electromagnetic interactions between the troposphere and the ionosphere/magnetosphere: books published by Stanford Very Low Frequency Group. There are also numerous research publications on the electromagnetic and particle interactions between tropospheric lightning and transient luminous events in the ionosphere: complete publication list. Consider, for example, Optical signatures of lightning-induced electron precipitation. These are, needless to say, technical papers. Nimur (talk) 16:48, 11 October 2011 (UTC)

Modified HIV-based cancer vaccine

Can someone please explain in laymans' terms how http://www.msnbc.msn.com/id/44090512/ns/health-cancer/t/new-leukemia-treatment-exceeds-wildest-expectations/ works? Why do the modified white blood cells start killing cancer? Are they trained to produce 3-BrPA when they taste cancer cells? 208.54.38.211 (talk) 02:57, 10 October 2011 (UTC)

White blood cells are a key component of the immune system, which recognize foreign cells and begin the process of their destruction. So when you have a cold or other infection due to some bacteria or other invader, the WBCs attack. One problem with cancer is that cancer is in many ways our own cells, so our own immune system does not recognize it as a foreign threat--if our immune system turns against our own cells, we are in serious trouble (see Autoimmune disease)! So a scientific advance is to train some WBCs (in particular, T cells) to recognize the cancer cells as foreign but distinguish them from non-cancerous cells.

In addition, WBCs only live for a few days. That's not a problem usually, because our bone marrow constantly produces new ones (in part adapting/responding to novel foreign invaders that may be detected). But special WBCs produced in a lab would not by regenerated because the marrow itself (in the body) was not altered to produce more of them--the body only contains as many as were injected for as long as that batch lives. Another scientific advance here was to make the anti-cancer WBCs able to replicate after being injected. DMacks (talk) 09:21, 10 October 2011 (UTC)

Actually, they don't kill cancer - they kill B cells of any kind. Chronic hypogammaglobulinemia is a side effect. For people within weeks of death, this is a tremendous advance, but it is a drastic treatment. Wnt (talk) 13:16, 10 October 2011 (UTC)

By B cells do you mean B-lymphocytes? I like the idea of merely training the white blood cells to produce anti-cancer agents around cancer cells instead of treating them as foreign (although if that could happen too, all the better.) Ad astra. 69.171.160.57 (talk) 15:53, 10 October 2011 (UTC)

Human Sensitivity to IR

Generally, I think, human beings are not sensitive to Infrared rays. Is it possible that some disease or deformation or DNA defect can make a human being sensitive to infrared rays.  Jon Ascton  (talk) 03:51, 10 October 2011 (UTC)

The receptivity of the human eye is actually a bell curve (three of them, actually), and a very tiny portion of the thin part of the bell curve is actually in the spectrum we call "infrared". this person found that by wearing goggles that completely blocked out the visible light, and then went out into bright sunlight, he could see a little bit of infrared. APL (talk) 04:18, 10 October 2011 (UTC)

That would have been near-IR, though. Not the kind of IR used in thermal-imaging. If the OP wants that kind of IR, then it's pretty much impossible - you would have too much interference from the IR the eye itself is emitting (although, I suppose there's no fundamental reason the eye couldn't be cooled to below usual skin temperature - it would require some pretty major evolutionary changes, though). Radio telescopes have the same problem - they need to be cryogenically cooled in order to avoid emitting too much radition in the part of the radio spectrum that they are trying to observe. --Tango (talk) 11:41, 10 October 2011 (UTC)

The only animals that can "see" in the infrared range, as far as I know, are certain types of snakes, and they use a special sensory system called a pit organ to do it, not their eyes. There are a variety of biophysical issues that make it nearly impossible for an eye-like mechanism to function well in that frequency range. Looie496 (talk) 15:36, 10 October 2011 (UTC)

I'm not sure the OP meant "seeing IR" when he said "being sensitive to IR." He could be thinking about something like light allergy, but against heat. Quest09 (talk) 15:46, 10 October 2011 (UTC)

Hold a warm object close to your lips. Can you feel the heat (infra red radiation)?--92.28.77.67 (talk) 16:04, 10 October 2011 (UTC)

Yes, but feeling is not "being sensitive." "Being sensitive" for me is being harmed/annoyed when in contact. Quest09 (talk) 16:55, 10 October 2011 (UTC)

The OP didn't say 'being sensitive', they said 'a human (being) sensitive to infrared rays'. Nil Einne (talk) 18:27, 10 October 2011 (UTC)

Thanks all. To be precise : when we press a button on a TV's remote control it emits IR from it's IR LED at front. That's invisible to human eye i.e. both the source of IR (LED) or any surface reflecting it. Is there any special biological defect that can make a man see it ?  Jon Ascton  (talk) 00:51, 11 October 2011 (UTC)

No (and, if they could, I wouldn't call that a "defect"). StuRat (talk) 01:36, 11 October 2011 (UTC)

I'm not sure what you really mean when you say that ! But I know a man who claims to see a very faint tinge of redness when his eyes are fully relaxed (i.e. after sleeping etc.) Could be a technical defect in IR LED ?  Jon Ascton  (talk) 02:37, 11 October 2011 (UTC)

Very likely. A lot of infrared LEDs will put out some light that's just barely in the "visible red" area. After your eyes have been closed for more than a couple minutes your eyes become completely dark-adapted, and that's when you're most likely to notice a very dim light. Your friend would probably be able to duplicate this effect when not tired by sitting in a completely dark room for ten minutes.

I used to use a bunch of cameras that had bright IR illuminators on them, and they had a faint visible-red glow. APL (talk) 06:35, 11 October 2011 (UTC)

Plenty of hotels have IR bulbs which you can sense via the skin even if you are blind. μηδείς (talk) 07:06, 11 October 2011 (UTC)

How a Latino could not be a Caucasien?

Hi clever people, please excuse my poor English, I'm French. Recently in the TV-serie "BONES" they find 2 corpses and the gifted Dr Brennan says "One is a Latino the other one is a Caucasian". I thought that Caucasian in American means something as White or European to indicate the difference with "Negro" or "Asian" and so on. And so for me Spaniards are obviously white, european Caucasians.

Question : What is this thing that I don't understand? Latinos have Spaniards ancestors, why not including them among the Caucasians? Thanks a lot for reading. Joël Deshaies-Rheims-France---85.170.172.37 (talk) 10:14, 10 October 2011 (UTC)

There is certainly some confusion regarding the term Latino: sometime it depicts a culture (Latin-American) and others it depicts a phenotype (native Indians of Latin-American and its descendents). Quest09 (talk) 10:29, 10 October 2011 (UTC)

Africans, brought to the Americas, and currently from Central/South America are referred to as Latino. They are not of Spaniard/European descent. To complicate it further, whites, from the same area, are referred to as Latino. The native people, from the same area, are referred to as Latino. Pretty much, anyone from Central/South America is considered Latino. In U.S. Government forms, Latino/Not Latino is asked separately from Race. So, you can be White Latino, Black Latino, or even Asian Latino. -- kainaw™ 12:37, 10 October 2011 (UTC)

All of that is true, and also there was a tremendous amount of what is politely called intermarriage between the Spanish colonists and both the native people and African slaves. The conquistadors did not bring wives with them to the new world, and they were active in territories that tended to have a higher population of Native Americans than the territories settled by English-speaking colonists.thx1138 (talk) 15:39, 11 October 2011 (UTC)

Race is a peculiar concept. I've read that the term "Hispanic" was coined by the United States Office of Management and Budget in 1978, [2] with "Latino" becoming popular shortly afterward - before then, curiously enough, according to the article it was used by people of certain politics to express affinity between Mexicans and French who were involved there. How "Latino" excludes Latium, I don't know; Italians are right out. In practice I think the term largely means people with a family history of speaking Spanish. What's funny is that white x black = black, and anything x "Hispanic" = "Hispanic" - unsurprisingly there are continually "news reports" that Hispanics are the "fastest growing minority" taking over the country. It is amazing how much weight can be placed on imagination and semantics. Wnt (talk) 13:30, 10 October 2011 (UTC)

I'm from Brazil and consider my self Latino, but not Hispanic. I've met some Italians that felt the same way. Dauto (talk) 14:46, 10 October 2011 (UTC)

Latino means actually from 'Latin(o)-America' in most cases. That would exclude people like Italians and such. If it means from from the Latium, it would include Italians. The word is simply ambiguous. Quest09 (talk) 15:51, 10 October 2011 (UTC)

In a context of forensic anthropology, "race" is usually just a way to say, "here's what an average person in this culture would think about this person." That's really all. So if I were to find a skeleton with certain facial characteristics, I'd be able to say, "oh, this looks more or less like someone who has a lot of their ancestry derived from people who lived on this continent." A shorthand of which is to say, "black" or "white" or "Asian" or "Latino" or what have you. From a strictly taxonomical point of view, this is a very problematic statement. But from the perspective of, "can we match this skeleton up to a number of possible missing people?", it's very useful. This is, anyway, what I gleaned from talking with a number of forensic anthropologists awhile back. So if I heard a forensic anthropologist in the United States say "this skull looks Latino," I'd assume, "this person looks like they have ancestry that was from South America, which is probably some form of European-Indian mix." If they said they were just "Caucasian," I'd assume they meant, broadly, "a very European looking skull." The skull would tell you exactly zero about what languages they spoke, what holidays they practiced, etc., obviously. I've of course no knowledge of what was necessarily meant by a fictional television show. --Mr.98 (talk) 16:53, 10 October 2011 (UTC)

Broadly, latino does mean of some nationality descended from the Romans, especially speaking a language descended from Latin. If you use Google translate from Spanish to Italian, latino translates as latino. Plenty of European Italians and others self identify as latino. Rudy Valentino was the "Latin Lover" in English but the amante latino in both Spanish and his native Italian. That being said, in the US, Latino usually means Latin American, specifically Spanish or even Luso-American and applies not only to Europeans but blacks and native Americans from Spanish American nations, and even, Brazilians. μηδείς (talk) 07:04, 11 October 2011 (UTC)

• So, to answer the question, the good Dr Brennan could probably identify a caucasian from their skull shape, but could only identify the other set of bones as latino if she had access to a good spae wife Elen of the Roads (talk) 15:51, 11 October 2011 (UTC)

Many Latin-Americans have mixed ancestry, similar to the Métis in northern North America; some are descended from the Aztec, Maya, Incas and other indigenous peoples of the Americas. ~AH1 ^(discuss!) 23:51, 14 October 2011 (UTC)

hydrogen peroxide

Does the regular 3% peroxide kill fungal spores such as ringworm spores? — Preceding unsigned comment added by 66.209.177.15 (talk) 10:18, 10 October 2011 (UTC)

Lots of studies - but they are of using high concentrations of H2O2 at elevated temperatures. Anecdotal for the 3% stuff. Collect (talk) 13:05, 10 October 2011 (UTC)

This is medical advice. See a doctor or pharmacist.μηδείς (talk) 06:50, 11 October 2011 (UTC)

It is not medical advice. If it was, then telling an OP that colloidal silver is antibacterial, is also medical advice. Plasmic Physics (talk) 08:43, 11 October 2011 (UTC)

This is definitely not medical advice, but general information about hydrogen peroxide and ringworm spores. Doesn't even say it's in vivo for that matter! If you want to see that boundary crossed, see #Push-ups and the "funny bone" nerve... Wnt (talk) 19:39, 11 October 2011 (UTC)

Timing of natural death

What makes a species have a typical life-span? I know that telomeres limits the number of years that humans can live, but are they present in any living creature? And are there other mechanisms to guarantee that a living being will die? Quest09 (talk) 10:24, 10 October 2011 (UTC)

We have an article on ageing in which some theories about the ageing process are explained. For the biology aspect of the question: Telomere actally talks about animal telomeres at some point. Generally speaking: If it has chromosomes (but not a Nucleoid) then it probably has telomeres. --Abracus (talk) 11:15, 10 October 2011 (UTC)

The relationship of the Hayflick limit to aging and death is still not very clear btw. It's also only part of the different "wear and tear" and "programmed death" theories and combinations thereof on the causes of aging (in this case DNA damage).

And yes, excluding gradual senescence and death by predation, diseases, etc. in organisms with negligible senescence, there are other mechanisms that ensure death. Semelparous organisms, for example, like octopuses and most salmon, die because they become completely consumed in ensuring reproductive success in a single event. The rapid senescence and death that follows is hormonal, the body actually tells itself to stop living (phenoptosis). In some species the body of the mother becomes the first meal of the offspring. In Stegodyphus lineatus, for example, the mother actually willingly lets herself be killed for food by her spiderlings. Also see Parent–offspring conflict.

Others die due to mechanical reasons. Weddell seals will eventually die when they lose their teeth, because they can't anymore maintain the breathing holes in Antarctic ice needed for access to water for food, and the surface for air and rest. Grazing mammals will also assuredly die when their teeth are eventually all worn out. Mayflies (which are also semelparous) will die because they do not have the means to feed themselves as adults (aphagy), etc.

In addition to Abracus' link, also see Evolution of ageing and this excellent site: http://www.senescence.info/ .-- Obsidi♠n Soul 13:47, 10 October 2011 (UTC)

Aging is caused by the fact that sexual reproduction is better at ensuring survival of the genes which produce bodies than is any attempt at immortality. μηδείς (talk) 20:53, 11 October 2011 (UTC)

Animal sadness

Apart from humans do other animals experience sadness. --86.45.146.152 (talk) 14:49, 10 October 2011 (UTC)

Yes, Jaak Panksepp has done a great deal of research on this topic. In animals sadness is most commonly referred to as separation distress (we ought to have an article about it) -- Panksepp calls it PANIC but that is widely felt to be a bad choice of terminology. There is also an animal emotion that you might call "despair", known as learned helplessness -- animals that experience bad things repeatedly without any way of controlling them eventually stop struggling and become apathetic. Learned helplessness is thought by many psychologists to be the animal version of human depression. There is a lot more to say about this topic -- Panksepp's textbook Affective Neuroscience covers it in depth. Looie496 (talk) 15:22, 10 October 2011 (UTC)

We do, its on separation anxiety in dogs. CS Miller (talk) 19:55, 10 October 2011 (UTC)

See Animal emotion for an overview. Richard Avery (talk) 15:27, 10 October 2011 (UTC)

(e/c) Also see Animal psychopathology#Depression and Stereotypy#In animals which also discuss anhedonia in animals subjected to stressful conditions, the equivalent of human despair.-- Obsidi♠n Soul 15:29, 10 October 2011 (UTC)

See elephant graveyard and elephant intelligence. Apparently elephants tend to die in places where they remember finding food and water easily--going there when they cannot forage in other places. Elephants are believed to recognize each other by running their trunk tips over each others' teeth. When an elephant dies, its teeth remain. Elephants have been observed spending time repetitively visiting elephant graveyards where they run their trunks over teeth and gently run their footpads over the bones. I think the proper interpretation of this is obvious. μηδείς (talk) 06:49, 11 October 2011 (UTC)

According to our article on the elephant graveyard, they are legendary. Googlemeister (talk) 13:18, 11 October 2011 (UTC)

No, they are not. Or, at least, the existence of a legend does not prove falsehood. Wikipedia itself is not a source, and elephant bone graveyards have been filmed and Elephants have been shown caressing the teeth and bones of the dead with their trunks and footpads. I assume this was broadcast on the American PBS show Nature or Nova. I'll see if I can find a ref for you. Quite a fascinating subject. μηδείς (talk) 20:57, 11 October 2011 (UTC)

Looking on YouTube I think the video of the elephants caressing the bones of their dead is either in the PBS Nature episode Unforgettable Elephants or Echo: An Elephant to Remember. I don't have the time to track down and watch these epsiodes to find the clip, though. μηδείς (talk) 21:03, 11 October 2011 (UTC)

Having slept on it I may also be thinking of an animal documentary which began with a dead chimp and its troop which then showed the elephant graveyard in a later scene. μηδείς (talk) 17:55, 12 October 2011 (UTC)

How do bats avoid bees and wasps?

Do bats eat bees? If not, how do they avoid they avoid them at night? Because bats come out at sunset and bees return to the hive at sunset, do bats perform culling of bee colonies? 69.171.160.57 (talk) 16:00, 10 October 2011 (UTC)

Bees return to the hive well before bats go out feeding. There are bats that are up during the day, but they eat fruit. Unless the bee is huge and looks like a big lemon, the daytime bats won't have any interest in it. -- kainaw™ 16:18, 10 October 2011 (UTC)

They both compete for nectar. I can't imagine an animal with the intelligence of a mouse wouldn't be able to figure out how to bite the head off a bee without getting stung, and then steal its nectar. 69.171.160.57 (talk) 16:45, 10 October 2011 (UTC)

That seems like an awful lot of work for not very much nectar. Anyway, this guy (best source of this I could find) says it's unlikely, mostly for the reasons given above. --Mr.98 (talk) 16:57, 10 October 2011 (UTC)

And no, they do not compete for nectar. There's a wide range of specifically nocturnal blooming flowers for nectarivorous bats (which are most emphatically not insectivorous, though they may be frugivorous esp. in Old World megabats) and moths alike. Plants that actually rely on them, rather than hymenopterans, for pollination.-- Obsidi♠n Soul 17:14, 10 October 2011 (UTC)

Oops. Strike that. It seems that nectar-feeding phyllostomid microbats do eat insects on the side. -- Obsidi♠n Soul 17:23, 10 October 2011 (UTC)

Hm... and megabats as well. Interesting. Though theirs is more opportunistic as they do not possess echolocation (with the exception of Rousettus aegyptiacus) and thus can't snatch insects from midair like microbats do. When they do eat insects though, it's for the protein, not for the nectar.

Also I'm wondering why a lot of sources say megabats are "all diurnal". The vast majority aren't. Out here flying foxes (which are unmistakably huge bats with characteristic slow wingbeats) do not come out until twilight which makes them crepuscular.-- Obsidi♠n Soul 17:46, 10 October 2011 (UTC)

Setting aside the relative rarity of nocturnal bees and wasps that might sting a bat, there is evidence that some bats are able to distinguish between different insects based on their wing beat frequency. Perhaps their target selection is good enough to avoid certain insects. See the theory and the practice. Impressive as that is, oddly on several occasions bats have crashed into me as I've walked through my garden at night. It's quite a complicated space and they have to patrol using complicated looping flight paths but it's almost as if they don't bother to update the large, slow moving objects in their model of a space very often. I guess tree trunks rarely move. Sean.hoyland - talk 18:09, 10 October 2011 (UTC)

I found a paper with percentages of insects found in bat diets. It seems they do eat bees and wasps. There's also an anecdote here of a small bat that attempted to catch a tarantula hawk (genus Pepsis, large diurnal wasps about ~2in), and the squabble that ensued.-- Obsidi♠n Soul 19:34, 10 October 2011 (UTC)

About satellite communication

What is the amplifier used in satellite communication. — Preceding unsigned comment added by 117.231.103.93 (talk) 16:19, 10 October 2011 (UTC)

An operational amplifier. 67.6.175.132 (talk) 23:34, 10 October 2011 (UTC)

The atmospheric radio window dictates that certain microwave bands are best-suited for satellite communications. You can start by reading about microwave communication. I've seen satellite-communication amplifiers that are "MMIC" (pronounced "mimics" - monolithic microwave integrated circuits), ASICs that contain multiple stages - a low-noise front-end amplifier, a gain stage or power amplifier, and a signal conditioner, digital decoder, demodulator, or other circuit elements.

Unique to satellite communication amplification is the need for incredibly high gain (because of incredibly low signal-levels), so there is a huge reliance on very low noise amplifiers. This often means that the first amp is not an op-amp - but a single BJT transistor. Your application may vary. Nimur (talk) 17:02, 11 October 2011 (UTC)

If you are purchasing equipment, the receive side is often done with a Low noise block-downconverter or low noise amplifier if you do not want to convert to an intermediate frequency. The transmit side is done with a BUC or Block upconverter. An output amplifier may be included, or you may need a separate high power amplifier. Graeme Bartlett (talk) 01:14, 12 October 2011 (UTC)

Push-ups and the "funny bone" nerve

So I'm curious, what action could cause the funny bone nerve to get pinched while one is doing push-ups? I notice sometimes that when I am doing push-ups, I feel a slight pinching sensation on the nerve (or sometimes a bit closer to the area above the left side of the end my forearm's bone (I forget its name)). So what is the action during a push-up that would cause this? Sir William Matthew Flinders Petrie | ^{Say Shalom!} 12 Tishrei 5772 16:41, 10 October 2011 (UTC)

Please see Ulnar nerve entrapment. 67.6.175.132 (talk) 23:37, 10 October 2011 (UTC)

Oy vey, this will be fun to tell my doctor about.... Sir William Matthew Flinders Petrie | ^{Say Shalom!} 13 Tishrei 5772 00:05, 11 October 2011 (UTC)

Please note that Wikipedia does not give medical advice, and while that may be one thing that can cause the nerve to get pinched, we have no idea that is true in your case. There could be other explanations, whether more mild or more serious, and you shouldn't rely on this one reference to decide whether or when to get treatment. Wnt (talk) 19:41, 11 October 2011 (UTC)

I am well aware of that. I was asking what such an action is (if anything), not what to do about it (which would be medical advice). During my next doctor's exam I would ask my doctor (by which I mean my general practitioner) about my elbow and give the description of the feeling, and, being the smart Jewish grandmother she is, she would either confirm or deny that it is this ulnar business; and then recommend a course of action based on her own knowledge of the human body. I wouldn't take any real course of action based on RD:S; I like my arm, tyvm. :p Sir William Matthew Flinders Petrie | ^{Say Shalom!} 13 Tishrei 5772 23:59, 11 October 2011 (UTC)

Drunkeness

Obviously humans get drunk on ethanol and from my personal observations, other mammals such as dogs and pigs do as well, but I was wondering if other animals had similar effects? Specifically, I am interested in flying animals, birds and insects, but would also like to know about fish and amphibians. Obviously they have different physiology, but perhaps the effects of ethanol are applicable to a very large range of creatures? Googlemeister (talk) 19:37, 10 October 2011 (UTC)

When I lived in southern California, there was a problem one summer with birds getting drunk off fermented berries along the highway and flying into buildings. So, that implies that birds get drunk. -- kainaw™ 19:52, 10 October 2011 (UTC)

Googling "birds drunk fermented berries" turns up a lot of information on the topic. -- kainaw™ 19:55, 10 October 2011 (UTC)

It seems to have been happening only a couple of weeks ago in Darwin. [3] "A species of parrot ... is on its annual drunken bender."  Card Zero  (talk) 06:14, 11 October 2011 (UTC)

I don't know if they get drunk first but a 1% ethanol solution by mass is enough to kill fish and crustaceans within 24 hours. Dragons flight (talk) 20:03, 10 October 2011 (UTC)

I would think that in creatures with less complicated digestive systems the amount that would get them drunk and the amount that would kill them would be about the same. I certainly wouldn't recommend trying to get a turtle or an ant drunk. Beeblebrox (talk) 20:27, 10 October 2011 (UTC)

Sap-feeding beetles actually love ethanol as it is a primary indicator that resin in trees are ripe for feeding. Beer in pans are commonly used as baits when collecting them. It seems fruit flies can also inhale alcohol vapor as food and can definitely get wasted. LOL. So can bees. Tropical fruit eating bats, however, seem to have evolved alcohol tolerance as a necessity, as a large part of their diet may include fermenting fruits.-- Obsidi♠n Soul 21:38, 10 October 2011 (UTC)

MythBusters tested whether vodka could be used as an insecticide on bees. It didn't work: the bees survived, but flew in a very erratic manner as if they were drunk. (Episode 44 in the 2006 season.) — Michael J 14:38, 11 October 2011 (UTC)

My remembrance of the theory from my organismic physiology class (late last century) is that drunkenness is caused by the effect of ethanol on cell membrane conductivity. That would imply a similar effect on all higher animals with neurons. μηδείς (talk) 21:16, 11 October 2011 (UTC)

Etymology of gestures, difference between intented and unintended gestures, and animals

Woman making the loser gesture

The international symbol of love

Is there some kind of Etymology research for gestures? Like: are there contemporary gestures of which the original -literal- meaning is lost but which would be easy to grasp for people in the Middle Ages? For instance, the gesture for loser is today clearly related to the letter L as is Air quotes to actual quotes. Maybe in 500 years or so, everyone forgot about that original meaning but is still using these gestures in a (possibly changed) meaning. Nod (gesture) has some unsourced explanation (babies nodding when they want milk), and shrugging had a (doubted and removed) explanation.

Slightly related, is there an "official" difference between gestures like "I'm sad", "I'm angry" or "I'm thinking really hard about this" which can be used on purpose but are expressed unintended as well by 4 year-olds when they are sad or angry, and on the other hand the "cultural gestures" one has to learn (like nodding)?

Last question, do animals have these "cultural gestures"? Has someone ever tried to learn a chimp to strike his belly to signal hunger? (instead of pushing the "Hunger" button) Joepnl (talk) 20:02, 10 October 2011 (UTC)

Don't know of any comprehensive research, but the origin of flipping the bird is discussed in the article. Turns out it has quite a long history. Beeblebrox (talk) 20:07, 10 October 2011 (UTC)

Animals communicate with gestures. Most don't have hands and use their body. There are thousands of examples of animal gestures from mating gestures to "get the hell away" gestures. -- kainaw™ 20:10, 10 October 2011 (UTC)

See Gesture#Neurology as well. Beeblebrox (talk) 20:11, 10 October 2011 (UTC)

Some animals can learn very complicated gestures. See e.g. Koko, who has been taught over 1,000 arbitrary gestures (which happen to be American Sign Language, but to Koko they are arbitrary). See also Great ape language. --Mr.98 (talk) 20:15, 10 October 2011 (UTC)

@Beeblebrox, Flipping the bird makes me wonder what it has to do with a bird, but that is precisely the kind of etymology I wanted, and I wonder if there's more like it. Thanks. @Kainaw I know animals use gestures, but I wonder if there are examples of groups of gorillas that have a sign for "Watch out for the crocodile" that other groups don't know. Koko proves that learning them works, but are gorillas also teaching them? The "non-cultural" gestures like "get the hell away" are hard wired evolutionary gestures I think. A peacock probably doesn't know he's making a gesture when he's raising his tail. (I know of a gesture like it that a lot of males along many different species don't need to learn) Joepnl (talk) 20:45, 10 October 2011 (UTC)

As a sidebar, isn't that woman in the picture giving the sign backwards? Falconus^{p t c} 21:21, 10 October 2011 (UTC)

Only a loser does it that way - OR, someone taking a picture in the mirror. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:09, 10 October 2011 (UTC)

I would rather describe Koko's gestures as signs, if we are going to distinguish between natural animal gestures and learned symbolic signs. In any case, Monty Roberts' use of gestures in "horse whispering", (by which he tames even problematic unbroken horses in minutes) such as using a raised hand as an implicit threat or responding to a horses' lip smacking as a request for sympathy is impressive enough to have made me weep to see it. μηδείς (talk) 06:41, 11 October 2011 (UTC)

Woodpecker facts I've been told - true or false?

Things that I've heard people say about woodpeckers - true or false?

1. If a woodpecker didn't shut its eyes when drilling, its eyeballs would fall out?

2. If a woodpecker's tail feathers are removed, it knocks itself unconscious as soon as it tries to drill (because it can't brace itself against the wood properly)?

3. Woodpeckers more than a couple of years old suffer from near-constant headaches and neck pain?

Some of these sound possible, but I've had a look at the woodpecker article, but these points are not specifically addressed. Thanks. --95.150.167.67 (talk) 20:20, 10 October 2011 (UTC)

2 seems to be true somewhat. The tailfeathers are used as support. Removing them probably won't affect their drilling ability though and won't knock them unconscious, but it would certainly have a large effect on their ability to climb trees. Wrynecks do not have stiff tailfeathers, but can still drill on vertical tree trunks by clinging to them with their legs. 1 is true. The eyes are fit particularly snugly to prevent trauma during drilling. The nictating membranes ("eyelids") are slid shut over the eyes just before impact and helps protect them from flying debris as well as restrain them somewhat. The brains are also fit snugly, small, located above the bill, and protected by shock-absorbing mechanisms in the jaw, which in turn makes 3 false. But then again, woodpeckers can't exactly come up to you and tell you they've got a headache. :P -- Obsidi♠n Soul 21:15, 10 October 2011 (UTC)

I asked one about various myths, and all he had to say was, "Ha-ha-ha-HAAA-ha!" ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:04, 10 October 2011 (UTC)

Dude. You taught him that laugh. And at least he's not teeing puttytats.-- Obsidi♠n Soul 22:27, 10 October 2011 (UTC)

Maybe you can infer by their movements that they suffer from neck pains, but how could someone test if woodpeckers suffer from headaches? — Preceding unsigned comment added by 88.11.244.183 (talk) 08:03, 11 October 2011 (UTC)

Just observe female woopeckers, if they don't want to couple, then what else could it be? Wikiweek (talk) 08:08, 11 October 2011 (UTC)

In the Tom and Jerry cartoon “Hatch up your troubles”, the woodpecker kid sometimes keeps his eyes open when drilling (but closes them more often). His or her eyeballs never fall out. – b_jonas 12:20, 13 October 2011 (UTC)

Drop impact absorption

So I'm not sure I'm phrasing this right, but I hope you guys will get the right idea about it. I am wondering, I have purchased both an Otterbox Defender for a BlackBerry Bold 9900 and a Commuter type for a 9700. Now these guys are built differently in which layer is where. The 9700 has the silicone skin against the phone and the hard plastic on top of that. The 9900 one is reversed with the hard plastic on the inside and the silicone skin on the outside (forget about the hard plastic holster and the fact that the whole thing together is a tank). So here is my question. Which design is better for absorbing the energy from an impact? Silicone inside and plastic outside or plastic inside and silicone outside? The plastic is some kind of Polycarbonate btw, but that doesn't mean much to me (by which I mean I don't much about it). Sir William Matthew Flinders Petrie | ^{Say Shalom!} 12 Tishrei 5772 20:29, 10 October 2011 (UTC)

It is impossible to answer this question without details of the structural composition of each design. 67.6.168.177 (talk) 22:01, 10 October 2011 (UTC)

I just said that the hard one was made of polycarbonate and the soft of silicone, so you know their composition. :p Of course, I guess I could link the specs so you can see their dimensions and such. Defender and Commuter Technical specs are at the bottom. However, I am asking which way absorbs better generally speaking? Hard over soft or soft over hard? Sir William Matthew Flinders Petrie | ^{Say Shalom!} 12 Tishrei 5772 23:21, 10 October 2011 (UTC)

Sorry, those are the same link. But without detailed blueprints of the phones and the cases both, I am not going to be able to give you a good answer, and neither is anyone else. These kinds of designs are almost always perfected by potentially destructive actual use testing (throwing them against the floor) so even if you gave us all the blueprints and we had the time to run them in simulators, the answer might still be wrong. 67.6.175.132 (talk) 23:51, 10 October 2011 (UTC)

(edit conflict)Well, I'm not sure how readily available blueprints for either are I'm afraid. Sir William Matthew Flinders Petrie | ^{Say Shalom!} 12 Tishrei 5772 23:58, 10 October 2011 (UTC)

I would think the soft material on the outside would work better, because otherwise the hard material may fracture when it hits the floor (or the floor may dent or crack). Perhaps a soft-hard-soft arrangement might be even better. StuRat (talk) 23:55, 10 October 2011 (UTC)

Depends on how thick they make it. I mean the Defender is pretty damn big already and very thick. Sir William Matthew Flinders Petrie | ^{Say Shalom!} 12 Tishrei 5772 23:58, 10 October 2011 (UTC)

Thicker and harder isn't always better (well, in some cases it is :-) ). Time to pull out an ancient Chinese proverb: "In the gentle breeze, the willow bends, while the mighty oak stands firm. In the powerful wind, the willow bends even more, and thus survives, while the mighty oak stands firm until it breaks. So, which is the stronger, then, the willow or the mighty oak ?" StuRat (talk) 00:07, 11 October 2011 (UTC)

Yes, all other things being equal, placing padding on the outside instead of the inside will change the damage the assembly will do to what it is dropped on at the expense of easier abrasion, and the advantage of less likely case cracking. 67.6.175.132 (talk) 02:31, 11 October 2011 (UTC)

time travel

first of all, i dont have any deep knowledge about physics. Im just wondering, if relativity says going faster that light is going backwards in time, and nothing can go faster than light, that just means the theory is saying that we cannot go back in time, is this right? if its right, then why do we still believe in time travel? — Preceding unsigned comment added by 203.112.82.1 (talk) 22:13, 10 October 2011 (UTC)

I'm not sure scientists actually "believe" in it. Fiction writers certainly do, as it makes for entertaining stories. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:18, 10 October 2011 (UTC)

I think at best scientists might "acknowledge that we're not entirely confident it's impossible." That's a long way from "believe". I'm not aware of any scientist who honestly thinks time travel might ever be a practical thing we could actually do. APL (talk) 06:22, 11 October 2011 (UTC)

Apparently one is hopeful. http://www.youtube.com/watch?v=oRWwI61so5Q ScienceApe (talk) 22:15, 11 October 2011 (UTC)

Scientists don't currently believe that going back in time is possible given our current understanding of physics. Going forward in time, even at different rates, is allowable (and actually achievable). As for why the idea exists outside of science, it is because it is an interesting idea, and allows for the creation of interesting plots, paradoxes, and other Cool Things™. But that's got nothing to do with whether the physics is real or not. --Mr.98 (talk) 22:37, 10 October 2011 (UTC)

i guess my question really is, does theory of relativity implies that going back in time is impossible?

Time travel says "Some theories, most notably special and general relativity, suggest that suitable geometries of spacetime, or specific types of motion in space, might allow time travel into the past". It's still one of the unsolved problems in physics. Clarityfiend (talk) 22:55, 10 October 2011 (UTC)

actually achievable*?wow, can you tell me more about it. — Preceding unsigned comment added by 203.112.82.128 (talk) 22:59, 10 October 2011 (UTC)

If you have magical powers to create any spacetime you want, then it is certainly true that there are solutions to general relativity that involve things appearing to travel into the past. However, it is unclear if there are any such solutions that are actually achievable given that one is starting with a nearly flat spacetime such as the one we live in. You tend to run into problems that need infinite energy, negative mass, or other things unknown to science. So while someone with Godlike powers might be able to open a bridge from the future to the past (e.g. a type of wormhole), it is unclear if any physically achievable configuration of mass or energy would allow that to actually happen in our universe. And the logical difficulties with causality violation seem so severe, that many people argue that it must be impossible to travel into the past. Dragons flight (talk) 23:08, 10 October 2011 (UTC)

I would go further than that and say that opening a wormhole to the past would change the past, which means that it's not really the past, just some kind of copy of what had been the past here in the present. So it would be like making a copy of what happened, and storing it in a transporter buffer and then materializing it and telling everyone, "hey look, it's the past!" The past itself would not change. It's like saying a historical reenactment is the real thing. A complete waste of time and effort for the non-fiction side of the aisle. 67.6.175.132 (talk) 23:43, 10 October 2011 (UTC)

67.6.175.132, is anything in your answer based on anything scientific? Or is it just based on television shows and amateur philosophy? APL (talk) 06:23, 11 October 2011 (UTC)

It's the "logical difficulties with causality violation" to which Dragons Flight referred. Anything, even a spacetime wormhole, which can change the past means, by definition, that what it is changing is not the past, but a strangely connected part of the present. 67.6.175.132 (talk) 20:21, 11 October 2011 (UTC)

If a particle in your reference frame is travelling faster than the speed of light, there is another reference frame, which relative to your initial frame moves at a velocity less than the speed of light, in which the particle travels backwards in time. Thus the one has two frames (that of the observer and that of the particle) in which time travels in opposite directions. You can put whatever you want in these frames, you can put New York in one and Jules Verne in the other, in which case he is travelling back in time. This is not some kind of "crack pot" science, and no scientist with an understanding of relativity would deny that superluminal travel entails time travel, this does not require any weird metrics or gravitational effects like wormholes, as it is a special relativistic effect, and so is valid for perfectly flat spacetime. The caveat that saves causality is that superluminal travel is not permitted, nothing can achieve it, and so the above scenario never arises.

Short answer, the objections about time travel to the past above are correct. But, long answer, if someone were to say that making three right turns is the same as making a left turn, but that no car can make three right turns, so, it is impossible to go left, would be incorrect. It could be logically possible to make one simple left turn even if no imaginable car could make three right turns in a row. That being said, no, you cannot travel backwards in time by any means, ultralight speed or wormholes. μηδείς (talk) 06:26, 11 October 2011 (UTC)

But general relativity on its own allows time travel - see our article on closed timelike curves. To rule out time travel you have to add some additional ingredient such as Hawking's chronology protection conjecture. Gandalf61 (talk) 10:23, 12 October 2011 (UTC)

Or causality, which is already a part of the foundations of general relativity so it's best not to separate the two. Does it help to think that infinite energy would be necessary? Dualus (talk) 17:48, 12 October 2011 (UTC)

October 11

Neutrino

Einstein has always maintained that speed of light was calculated for an electromagnetic wave.Holding that neutrino travels faster than it seems unrealistic considering it is not an EM wave.But should we consider that Theory Of Relativity for a non EM wave particle?Bdaysuneet (talk) 07:26, 11 October 2011 (UTC)

Should we consider that the theory of relativity for a non EM-wave particle is what? You have half a sentence there. Plasmic Physics (talk) 08:37, 11 October 2011 (UTC)

There's a fair bit of investigation to go through before assuming that. Some neutrinos were detected at the same time as a supernova explosion was seen recently which indicates they don't go faster than light. If there isn't some silly mistake and the results are confirmed there will be quite some job trying to reconcile it with that result. Dmcq (talk) 09:40, 11 October 2011 (UTC)

We should wait until we have evidence that there are neutrinos that travel faster than light rather than ill-informed reporters misrepresenting a story on a topic of which they have very little understanding. -- kainaw™ 14:42, 11 October 2011 --(UTC)

may i say something regarding on weather travelling faster than speed of light is possible or not? for as much as einstein seems to insist according to his formula of E=MC2 showing the reason why it is impossible for anything to travel faster than light, I on the other hand have been working on this for sometime and have found that due to four errors weather made by science or einstein for not spoting it where ENERGY-MASS-MATTER-E=MC2 and the big bang is of concern I have found what I belive enough evidence within those i have just mentioned, where it has given me a 70% probability that travelling faster than speed of light is possible, although saying that I have always belived that there are certain particles not yet found that are travelling faster than speed of light, the first particles to come out of the big bang and the last particles at the end of the impact that created our universe, I am know as a historian science/physic researcher and thearist analist--188.28.166.239 (talk) 00:29, 12 October 2011 (UTC) (UTC). carlos portela

If you have real evidence to counter the vast amount of research that confirms Einstein's claims, then now would be an excellent time to publish a paper in a respected journal, but, if you write your paper in English, do get someone to proof-read it first. Dbfirs 08:30, 12 October 2011 (UTC)

first i like to say that everytime i log in once i try to go anywhere it logs me out for some reason, so regarding what you have said..if you could help me in how or where i can really send my valuation regarding what i have written,, not that i want to discredit any one in science or einstein for that matter..is just until it gets read by a real proffesional scientist or someone in astrophysics.. i really don't know how much i got it right, although saying that my explenation according to those i have explained to..being friends..they find it it makes sence, i have send a report to metro news paper within hours of hearing about the atom smasher lab in europe claiming they might have successfuly recorded one of their particles going faster than light..i have even send them an email aswell which i got it from their own website..but up to now no reply..i seem to be finding a big problem in anyone considering in hearing me out..it may be all hot air and nothing..but what if i am right and got something?/ ... for if i got something it would also mean that man made machine with todays technology, within five years a spaceship could be build where it could travel more than 100,000 miles an hour..without hurting the pilots inside..i just need someone honest within the science field or media who can give me a chance to read my report and take me a little serious..i have proff that i been on to this project since last year.. but was not ready to make it public or say anything as it is kinder unfinished yet..but since hearing the news i felt i had to try and get my word out. any ideas?? who i could get in touch with, where they will reply back with their comment??.. any ideas... mfe_science/sittos_science: carlos portela — Preceding unsigned comment added by 188.28.11.17 (talk) 22:21, 12 October 2011 (UTC)

It is unlikely that you will easily find anyone who will take you seriously because 99.999% of theories that contradict both established beliefs and substantial evidence turn out to be total balderdash. Einstein was an exception! Take a careful look at your work and decide whether it is worth writing it up carefully in your own language (Dutch?) with as much actual evidence as you can provide, then take it to someone at the University of Amsterdam (if you live somewhere near), where you will possibly find a research student who might look over your paper and tell you whether you are writing anything that makes scientific sense. Dbfirs 06:23, 13 October 2011 (UTC)

well thanks for that..although i am not dutch i know my spellings are not corect but that is becaous my keyboard is crap working..lol.. i am spanish living in london and my best language to write it on would be english since been living here to long.. one question..would i be violating any legal system if i was to send an article to all news papers at same time?/ rather that one at a time wating for each to see if they respond or not before moving on to send it to another news paper, i mean is not as if i want any payment for it..anyway thank you for responding to my writing sorry if it annoy you the spellings..maybe i am missing something, just is to logical i guess specially when if the big bang is to be true within that theary. there is enough evidence or argument to verify that there was at least at one time in the life of the universe where some particles did travel faster than speed of light.. what annoys me is that einstein insisted that nothing travels faster than light according to his equation and everyone just seem to accepted it.. anyway thanks again for your kind replies..shall not bother you no more..lol and what is wrong with wikipedia that when i come here it logs me out automatic,grrr soo annoying,,mfe_science/sittos_science188.28.242.170 (talk) 11:34, 13 October 2011 (UTC): carlos portela

What is the function of the long carbon tail of Chlorophyll a(and b,d also)?

I guess that it might affect the absorption of sunlight, and may distract free radicals that may cause harm to the structure. Is it right?--202.153.93.50 (talk) 09:54, 11 October 2011 (UTC)

No. It's a water-insoluble anchoring structure. It's discussed in Chlorophyll a.-- Obsidi♠n Soul 14:04, 11 October 2011 (UTC)

The article (which is itself not a reliable source) does not contradict the IP OP's speculation. I'd be surprised to learn that the tail doesn't affect the absorbativity, if that is a word. The rule in biology is multiple overlapping functions. His questions seem quite fertile, actually.μηδείς (talk) 21:22, 11 October 2011 (UTC)

Woodward's rules are a good guide to determining what (if any) effect various groups have on the frequency of uv/vis absorption of an organic structure. For chlorophyll a, the long chain is fairly decoupled from the chromophore (the central ring structure with magnesium) so the fact that it's a "long chain" probably has little to no effect. Alkyl groups in general do not have any noticeable uv/vis activity (usually need pi bonds for that), and even an isolated pi bond such as the alkene in the chain only absorbs deep in the uv. This is all in contrast to alkyl groups directly attached to the chromophore (see discussion in the article). The electron pathways and regions of excitation in the various photosystems seem pretty well studied, and I don't see any claims that the long chain is involved. The idea of being not involved in the light-harvesting and energy-transfer processes is actually a pretty important possibility (vs "probably some effect, even if we don't know it"). Any light absorbed by the anchor or any additional steps in the transfer pathways represents a loss of efficiency, so it's not a bad idea to have an anchor that doesn't do any photosynthetic-pathway activity. On the other hand, it could be a structural element that helps stabilize a certain excited state or something like that...probably could look at a 3D structure of the molecule as bound in its larger complex to see exactly where the chain is. One of the cool things about biochemistry is that the structures have actual shapes and each atom is in a certain place (and therefore can only react with other things nearby)...my bio students often have trouble seeing beyond "there's this amorphous black-box thing called chlorophyll", words written on reaction-arrows. DMacks (talk) 21:54, 11 October 2011 (UTC)

Er... its function as an anchoring structure is well known enough that calling Wikipedia an 'unreliable source' in this case is pretty unwarranted. They do help keep the chlorophyll molecules arranged neatly in thylakoids, maximizing the surface area and thus efficiency in gathering light. That can be considered as 'affecting the absorption of sunlight', though that's reaching. Defusing damage from free radicals is accomplished by accessory pigments as well - carotenoids (which do have overlapping functions) - not the tails.-- Obsidi♠n Soul 23:37, 11 October 2011 (UTC)

I am sure I said overlapping function, not wrongly attributed function. Indeed, "contradict" means to negate, not just to give an alternative. For example, the fact that jawbones are jaw bones does not contradict their use in hearing. And saying the article is not a reliable source in no way implies it is known to hold false information. Now, I am not saying either that the long chain has indeed been shown to serve the OP's proposed purposes. And I don't have sources. (My focus of study in biology was above the organismic level.) And indeed the anchoring function is clear. But larger molecules do have broader spectra and lipid chains do bond free radicals. The hypotheses are not uneducated. See subcontraries.μηδείς (talk) 00:45, 12 October 2011 (UTC)

That tail is a saturated hydrocarbon, so I really doubt it's going to help much with absorbing sunlight, nor interacting with free radicals. Compare Geranylgeranyl pyrophosphate. Wnt (talk) 03:15, 12 October 2011 (UTC)

A speed debugger?

Let's say you're a really really great speed reader and an equally good computer programmer.

Can your expertise in speed reading help you debug computer language codes? -- Toytoy (talk) 14:07, 11 October 2011 (UTC)

Programming languages are not exactly prose.-- Obsidi♠n Soul 14:25, 11 October 2011 (UTC)

Not sure about reading, but I've seen a speed typist at a little better than 100 words per minute who was a really impressive programmer provided the algorithms were simple enough that they didn't require much thought. A lot can be accomplished with just minor variations on stock solutions for basic data structures and algorithms, and this guy would just burn through those. Dragons flight (talk) 14:43, 11 October 2011 (UTC)

It is possible to pick out certain types of errors in "speed" mode. For example, one of the most common errors in C coding is to write = where == is needed -- I can generally spot that error in a quick scan, if the code is formatted properly. More subtle errors require thought to detect. (Note: I don't believe there is really such a thing as a speed reader. The faster you go through the text, the less thought you can give to what you are reading.) Looie496 (talk) 15:46, 11 October 2011 (UTC)

If you scan code for errors a lot, you get better at it. I grade programming homework. So, every week, I have to scan a few hundred programs for errors. The result is that I can quickly scan my own code for errors - most of the time. Sometimes, the error is very hard to find and it takes forever. The true end result is that I am a rather fast programmer. I've gone to programming competitions in the past and done very well based on experience and speed. -- kainaw™ 15:51, 11 October 2011 (UTC)

Some time ago, there was a spectacularly esoteric C program with a bug, posted on the reference desk. Not to boast - but I solved the problem within six minutes after it was posted. I had been working at a small silicon vendor company, and my job regularly entailed reading awful awful uncommented C++ code for embedded systems; I had taken a momentary break to "refresh" myself by reading the Reference Desk; and this "obfuscated C code" question seemed like a cool breeze. I agree with Kainaw - if you spend a lot of hours each week staring at program code, you adapt your thought processes and start thinking like a compiler. Anecdotally, I have found that during weeks when I am most proficient at speaking with humans, I am less efficient at communicating with computers, and vice-versa. Program-code syntax is quite different from human language syntax, and if you spend forty or eighty hours in a week thinking in C, it does become difficult to switch back to English. Nimur (talk) 16:11, 11 October 2011 (UTC)

"Speed reading" is mostly a joke, anyway. It's not really much different than "skimming". Some people can read faster than others, but those people you saw on TV back in the 80s turning the page every second weren't really absorbing much of the text they were looking at. Here's a good article. APL (talk) 17:23, 11 October 2011 (UTC)

I would be fascinated to see some solid psychological research literature exploring the upper bounds of the "words per minute" rate of reading. Mostly, I think I am interested to see how the measurements would even be formulated. It appears that Cecil Adams used comprehension-testing, after the reading tests, to determine "effectiveness" of reading at various words-per-minute rates. Who are the preeminent experts in this sort of quantitative psychology research, and what books or journal articles have they published? Nimur (talk) 17:30, 11 October 2011 (UTC)

Much depends on what level of "comprehension" is required. I think of skimming as being monitored by some "dashboard instruments" - for example, how interesting the text is (which is evaluated long before understanding it), and front and center the ever-important bullshit-O-meter. Wnt (talk) 19:51, 11 October 2011 (UTC)

The cognitive skills involved in debugging are wide and varied, overlapping with reading and programming, but are subject to the power law of practice, and debugging skill will vary by individual more than by previous skill acquisition. So I would guess that speed reading will not have a large impact but programming skill certainly will. 67.6.175.132 (talk) 20:17, 11 October 2011 (UTC)

My experience is that you won't find the hard bugs when speed reading code. But it's easy to spot code made by beginners that needs extra attention. For instance, code that is copy-pasted or reversely a ridiculous use of inheritance introducing just one or a few methods at a time (Class names with "base" or "context" in it are a sure spell). And it's very easy to find places where errors will occur. In our 50 man year project almost every single line that used Cultures directly or was depending on it in any way introduced a bug. Using regular expressions is not "almost" but "each and every single line". See also Anti-pattern. Joepnl (talk) 01:53, 12 October 2011 (UTC)

Fanning and temperature

Why, when fanning oneself with some sort of object (sheet of paper, for example) or with a fan, the air feels cold? By this I mean, when we fan ourselves, we're rapidly moving the air particles around us; rapidly moving particles tend to move faster than those moving at slower speeds, so why is this moving air not warm? 64.229.153.152 (talk) 20:03, 11 October 2011 (UTC)

Because the movement you induce on the air molecules is miniscule compared to the speed those molecules were already moving. Googlemeister (talk) 20:13, 11 October 2011 (UTC)

Please see perspiration. 67.6.175.132 (talk) 20:18, 11 October 2011 (UTC)

Have a gander at Wind chill old bean. Quintessential British Gentleman (talk) 20:56, 11 October 2011 (UTC)

Indeed, turning on a fan in a closed room will increase the air temperature ever so slightly (due to the energy you are imparting into the air). However, as Quintessential British Gentleman's link points out, the reason you feel cold is due to the increased convective heat losses that occur due to the high wind speeds. - Akamad (talk) 21:17, 11 October 2011 (UTC)

If I remember the results of the calculation correctly from studying the gas laws in high school chemistry, individual air molecules average a speed of about 1,000 miles per hour, but in random directions, at room temperature. Fanning adds a very small coherent velocity change on top of this. μηδείς (talk) 02:30, 12 October 2011 (UTC)

In addition to the increased convective heat loss mentioned above, it will aid evaporative cooling if you are sweating and the humidity is not too high. -- 49.229.25.26 (talk) 02:51, 12 October 2011 (UTC)

(ec)If the air is above 37 C, the convective effect on heat transfer is no longer beneficial, but then it should help sweat evaporate faster. I wonder if there is some situation in a hot desert where sweat already evaporates instantly, where fanning does no good for either purpose and makes a person feel hotter. But such a circumstance is surely dangerous at best. Wnt (talk) 02:51, 12 October 2011 (UTC)

If the air is still then, even in a desert, the humidity of the air within a couple of milimetres of your skin will still be quite high, prevently the rapid evaporation of sweat. A fan mixes the air so you get dry air next to your skin and you get faster evaporation. That should mean that fans are more effective in a desert, not less. --Tango (talk) 12:04, 12 October 2011 (UTC)

Magnesium based leavening?

Are there any possible leavening agents with magnesium? Would magnesium oxide leaven bread? Magnesium carbonate? I have a feeling there may be only one way to find out. 67.6.175.132 (talk) 22:54, 11 October 2011 (UTC)

I don't think so, what gas are they going to give off when cooked. Magnesium bicarbonate is not stable as a solid to be useful. Graeme Bartlett (talk) 00:03, 12 October 2011 (UTC)

The logical choice would be magnesium carbonate, which is very stable. Dominus Vobisdu (talk) 09:33, 12 October 2011 (UTC)

Sure, Magnesium is essential for any type of life, including Brewer's yeast. See Magnesium in biology. On a serious note, magnesium carbonate would probably leaven bread in sufficiently acidic recipes. However, as the article notes, it may work as a laxative in high concentrations. Experiment at your own risk. Buddy431 (talk) 03:38, 12 October 2011 (UTC)

Yes, magnesium carbonate would work just fine if paired with an acid like cream of tartar. Besides the laxative effect, the taste would probably be horrible, too, as magnesium salts generally have a very unpleasant bitter taste. Dominus Vobisdu (talk) 09:31, 12 October 2011 (UTC)

Are there any magnesium compounds which taste good? Dualus (talk) 17:51, 12 October 2011 (UTC)

October 12

menstrual taboo

Many cultures and religions have taboos against sexual intercourse while a woman is menstruating. Are there any physical or physiologial reasons why this should not occur? Are there any benefits to sexual intercourse during the menstrual cycle? 99.250.117.26 (talk) 00:09, 12 October 2011 (UTC)

Blood, contraception. μηδείς (talk) 00:30, 12 October 2011 (UTC)

Are there any benefits to sexual intercourse during the menstrual cycle? Because otherwise you'd have to wait 30 years and never have any children? (Well, there are ways of preventing menstruation, but only recently in human history, and they still prevent having children). I think you're confusing the menstrual cycle with menstruation. --Colapeninsula (talk) 09:13, 12 October 2011 (UTC)

Perhaps I am confusing the two but I was wondering if there were any benefits (to the woman) in engaging in sexual intercourse while menstruating. I read the wiki article but this didn't answer my question. 99.250.117.26 (talk) 16:58, 12 October 2011 (UTC)

In PMID 20577749 it says it's not likely to be unhealthy, just messy. Dualus (talk) 17:55, 12 October 2011 (UTC)

Against: blood. For: contraception. μηδείς (talk) 00:30, 12 October 2011 (UTC)

There is little blood there, μηδείς, contrary to popular belief. It's actually the uterine lining. And you are also wrong about contraception. While many women may be more likely to become pregnant mid-cycle, the chance of conceiving during menstruation may be higher than previously thought. Another fact to know: Sperm can live up to 5 days in a woman's body. Quest09 (talk) 23:04, 12 October 2011 (UTC)

Well, yes, I know it's not all blood but that's what people call it and of course it is not a foolproof method of contraception but I am not the only person to have taken advantage of it. μηδείς (talk) 01:29, 13 October 2011 (UTC)

It's almost no blood there, just 35 milliliters during a monthly menstrual period, it doesn't matter "what people call it." And it's certainly not a contraception method. The high failure rate of calendar-based contraception is very well-known. Quest09 (talk) 14:55, 13 October 2011 (UTC)

Granted, but still better then nothing. Googlemeister (talk) 15:21, 13 October 2011 (UTC)

Yes, checking the most fertile days to avoid pregnancy is better than nothing, but if you do it all the time, it equals nothing. Quest09 (talk) 16:03, 13 October 2011 (UTC)

Aboriginal North Americans and alcohol

Is it true or accurate that Native North Americans have something "physiological" about them that results in an inability (or significantly reduced ability) to metabolize alcohol in their bodies as compared, say, to Whites? Or, is this more of a myth and that the apparent "inability of Indians to handle their liquor" impacted more by stereotyping and cultural oppression? 99.250.117.26 (talk) 00:33, 12 October 2011 (UTC)

There are some genetic factors (see Alcohol_tolerance#Alcohol_tolerance_in_different_ethnic_groups), but a lot of it is social-cultural as well. They are mutually reinforcing (for the negative) in this case — rampant poverty plus genetic factors begets more rampant poverty and so on. --Mr.98 (talk) 00:58, 12 October 2011 (UTC)

Decades ago the claim was frequently made that Aboriginal Australians had a similar problem metabolising alcohol. That dogma seems to have now faded in favour of the view that the problem is more related to generational disadvantage. HiLo48 (talk) 01:44, 12 October 2011 (UTC)

You may find this article interesting, regarding the theory that response to alcohol is culturally mediated rather than physically mediated. --TammyMoet (talk) 09:41, 12 October 2011 (UTC)

I would just emphasize again that it's always a dynamic between the two. It's never an "either/or" situation — it's a "both" situation. --Mr.98 (talk) 11:57, 12 October 2011 (UTC)

About the alleged FTL neutrinos

What if they only exhibit this FTL behavior some of the time. Like... I'm just making this up, but lets say the neutrinos passed through holes in space time that open up only very rarely and the last experiment just happened to catch it. But if they were to repeat the experiment, they notice no FTL behavior because the holes didn't appear that time. Isn't something like that possible? That an experiment just happens to catch a rare occurrence that isn't likely to be repeated? ScienceApe (talk) 03:30, 12 October 2011 (UTC)

That would be even more weird than if we were to find that they always travel at the same FTL speed. And more unlikely. --Lgriot (talk) 07:56, 12 October 2011 (UTC)

Also for your information the CERN has repeated the test hundreds of times already. So it is not a rare occurence, the results were consistent. --Lgriot (talk) 07:58, 12 October 2011 (UTC)

Hm. Sounds like something for the Journal of Irreproducible Results. Comet Tuttle (talk) 17:12, 12 October 2011 (UTC)

As Lgriot stated, the faster-than-light measurement has been performed repeatedly and the same speed is measured each time. What he didn't state is that the people performing the experiment do not consider this evidence of faster-than-light speed. They consider it an error in the accepted method of measuring the speed of near-light-speed particles - and published their findings with the purpose of fixing the measurement error. It was a bunch of newspaper reporters who spun the story around to claim that the neutrinos were traveling faster than light. -- kainaw™ 17:22, 12 October 2011 (UTC)

It may be more fair to say they weren't sure it was an error when they published the results. Have they identified the most likely candidate sources of error? Dualus (talk) 17:57, 12 October 2011 (UTC)

My understanding is it has been attributed to a difference in the mass of underlying rock, causing a slight difference in gravity to have caused a relativistic error between clocks at the two locations. See here. μηδείς (talk) 20:39, 12 October 2011 (UTC)

The article does say too that the OPERA scientists apparently plan to rebut the lone paper making that attribution. --Modocc (talk) 07:00, 13 October 2011 (UTC)

Knappable stone in Southwestern CT

So I am wondering, what kinds of stone that are good as cores for flint-knapping (ones heavy in silicates) can be found in the area of Fairfield County, CT, and where in the county can they be found? Westchester, NY is okay as well. I knapped some basalt earlier today and am eager to create some more stone tools. I know I can find quartz, but I'm looking for flint and chert, maybe something even better like obsidian. Sir William Matthew Flinders Petrie | ^{Say Shalom!} 14 Tishrei 5772 03:34, 12 October 2011 (UTC)

Is this map: [4] helpful? It would appear that most of SW connecticut is of oceanic schist and gneiss deposits; I'm not sure these provide the sort of knappable stones you're looking for. There appears to be a band of rocks running along the CT/NY border through Danbury (the blue band on the map) and possibly down the I-684 corridor in NY which has some quartzite, which Wikipedia's article seems to indicate can be used as a substitute for flint. That may be your best shot. --Jayron32 05:20, 12 October 2011 (UTC)

Ah. good map. No, I'm afraid not. :( Schist tends to flake in a manner similar to baklava (except not as tasty), gneiss is too hard. Quarzite would make a good hammerstone though. I think I should order some flint. Stupid glacier messed up the geology and likely pushed all the good stuff into that terminal morraine of its. ._. Wait just a moment... Great Captain Island is a recessional morraine? This report from the Audobon doesn't say much about the types of rocks. [5] :( Sir William Matthew Flinders Petrie | ^{Say Shalom!} 15 Tishrei 5772 03:46, 13 October 2011 (UTC)

Power Input vs. Voltage Output.

Hello.

If I have a simple circuit as shown below:

Power in--------Resistor--------------------Voltage Out

And I can determine the power coming in to the circuit but only the voltage coming out ( I don't know the resistance across the circuit), what sort of relationship can I expect between the power input and the voltage output?

114.77.39.141 (talk) 04:50, 12 October 2011 (UTC)

If you know the power P consumed by a resistor and the voltage V across the resistor, you can compute the resistor's resistance as $R={\frac {V^{2}}{P}}$ . That's a variation of the equation $P={\frac {V^{2}}{R}}$ listed at Electric power#Direct current. Red Act (talk) 06:18, 12 October 2011 (UTC)

... and please note that, as mentioned by Red Act, the voltage is measured across. The concept of "Voltage out" does not make sense for a resistor, and the power is dissipated by the resistor (mainly turned to heat). Dbfirs 08:12, 12 October 2011 (UTC)

Ok what about in the case where the signal is AC, and the relationship between V, I, P and R is not linear; are there any assumptions/relationships I can assume in a case like that? 114.77.39.141 (talk) 09:01, 12 October 2011 (UTC)

This makes no difference because the relationship is linear at any instant, and for a pure resistance there is no phase difference between the voltage and current. You can just use the RMS values as if they were DC. (Are you sure you are asking about a passive resistance? The phrasing of your question suggests that you might have some sort of semiconductor "black box" where relationships are not linear.) Dbfirs 14:08, 12 October 2011 (UTC)

The 'resistor' is actually a dead cochlea, so I assume due to a lot of changes in the extracellular environment, which leads to non linear changes in resistance.114.77.39.141 (talk) 22:06, 12 October 2011 (UTC)

I think a dead cochlea would operate as a linear (Ohmic) device over a fairly broad range of operating conditions, because there isn't much of a reason why it wouldn't. The current going through a dead cochlea doesn't go through a lot of loops, so there wouldn't be much inductance, there are no thin dielectrics involved, so there wouldn't be much capacitance, there are no major crystalline structures involved, so there wouldn't be nonlinearities due to band gaps, and the tissue is dead, so there wouldn't be any neural action potentials involved. There will be nonlinearities at very high voltages or frequencies, but otherwise, I think Ohm's law should hold quite well. Red Act (talk) 00:32, 13 October 2011 (UTC)

Agreed, though, of course, if you are causing a large power dissipation then the heat produced will cause physical and chemical changes that will change the resistance, probably permanently. Dbfirs 05:45, 13 October 2011 (UTC)

Surrogate instead of abortion

Lets say a mother doesn't want the baby, but the father does. Is it possible to remove the embryo and grow it in a surrogate mother? ScienceApe (talk) 05:02, 12 October 2011 (UTC)

It would depend a lot on your legal jurisdiction, and on how good your lawyer was. --Jayron32 05:06, 12 October 2011 (UTC)

...not to mention how good your surgeon is! Richard Avery (talk) 07:02, 12 October 2011 (UTC)

Plural surgeons in the distant future, if ever. Dualus (talk) 18:02, 12 October 2011 (UTC)

Embryo#Viability says "Current medical technology does not allow an embryo to be transplanted from the uterus of one woman to that of another." --Colapeninsula (talk) 09:21, 12 October 2011 (UTC)

(ec) Short answer: no.

Long answer: to answer your question, I need to break it into separate questions:

Question 1: Is it possible to detect pregnancy before the embryo has implanted, then remove the embryo and insert it into another woman's uterus, and have it implant there?

Answer: Implantation (human embryo) occurs about 9 days after ovulation (6-12 days, according to our article). Pregnancy can be detected as early as 6 days after ovulation. Pregnancy tests work by detecting Human chorionic gonadotropin, which is produced by the developing embryo after conception, and later by the placenta. Therefore, theoretically, there may be a window of a day or two between the earliest possible detection of pregnancy and the implantation of the embryo. The problem, then, would be the localisation and successful harvesting of the embryo on its way down the fallopian tubes (or in the uterine cavity just before implantation). To my knowledge (and after googling high-resolution ultrasound), localizing an embryo at this stage is not within reach of current ultrasound technology. The eggs that are harvested for IVF are contained in larger structures (follicles) in the ovaries, and what is harvested from there is a fluid, from which eggs are isolated under a microscope. One might perhaps attempt something similar, like infusing a suitable liquid intraperitoneally near the opening of the fallopian tubes, and collecting fluid from the uterus, trying to flush the embryo into a container. This is definitely sci-fi, and risky with respect to future pregnancy. Another possibility, would be to remove the uterus and fallopian tubes, and carefully under a microscope dissect the path that the fertilised embryo travels, in an environment with controlled temperature and humidity. Such a procedure would of course rule out future pregnancies. I would rate the chances of success for both strategies as slim. Harvesting fertilized eggs using the second method has been successfully performed in mice [6], but the mice were killed in the process.

Question 2 Is it possible to remove an embryo that has implanted, and transplant it to another woman's uterus, and let the pregnancy continue there?

Answer: This is definitely science fiction. As the Implantation (human embryo) article explains, implantation involves a complex interplay between maternal and fetal tissues. To attempt such a transplant, you would need to have the surrogate mother's uterus somehow prepared to take over the function of the biological mother's uterus, at a stage where the function of the latter has been strongly modified by the embryo, through processes that are not fully understood, and then accept a graft consisting of an embryo and tissues from the biological mother. There is no way that this is remotely possible with current knowledge and technology.

Question 3: Is it possible to remove a pregnant woman's uterus, and transplant it into another woman, allowing the pregnancy to continue there?

Answer: According to our article uterus transplant, there has been performed a few attempts at transplantation of human (non-pregnant) uterus, and it is debatable whether any of them can be considered successful. None have resulted in pregnancy, and one caused the death of the recipient. However, pregnancy in a transplanted uterus has been achieved in immunosuppressed sheep, so human uterus transplantation may at some time in the future become an option for women who lack a functioning uterus. Transplanting a pregnant uterus is a different story. You would (at the very least) need to somehow replace the function of the Corpus luteum. Conclusion: This option is also out of reach of current technology. --NorwegianBlue ^talk 09:37, 12 October 2011 (UTC)

See axolotl tank. μηδείς (talk) 20:35, 12 October 2011 (UTC)

The axolotl tank mentioned above is a semi-artificial uterus from Frank Herbert's science fiction series Dune. While that is not a particularly useful answer to the OP's question, our artificial uterus article (which clearly states that it deals with a "theoretical device") may be of interest. -- 110.49.122.25 (talk) 06:19, 13 October 2011 (UTC)

How long does it take for acquired immunity to form

Hepatitis B viral antigens and antibodies detectable in the blood following acute infection.

Hi. The title question pretty much says it all. If a human being were to be infected by a mild-to-moderate pathogen he's never encounted before, how long would it take him to acquire immunity to that given pathogen? Or does it depend on the pathogen itself? Thanks. Leptictidium (mt) 09:49, 12 October 2011 (UTC)

It depends on the pathogen and, importantly, on whether he's been exposed to similar pathogens before. I think it's usually on the scale of a few days, though. --Tango (talk) 12:12, 12 October 2011 (UTC)

A textbook answer would be that IgM antibodies develop in about three weeks, and that IgG antibodies appear several weeks later. On a second encounter with the antigen, when immunity has been aquired, the response is much faster (IgG production within less than a week). Take a look at the diagram that shows antibody production after hepatitis B infection. Anti-HBs antibodies appear after several months. These are the antibodies that are protective against future infection. --NorwegianBlue ^talk 00:07, 13 October 2011 (UTC)

Sun seen from space

If we were in space (outside any effect of scattering), and looked at sky while the sun were in the middle, how would it look like and can we see the stars around as in the night? Are there any photos from NASA that can explain this?--Almuhammedi (talk) 12:37, 12 October 2011 (UTC)

Well, without some sort of protection, you would be blinded almost instantaneously by the luminous intensity, and your retinas will be permanently scarred by a combination of the full spectrum, including but not limited to gamma, x-ray, and ultraviolet. It would look much the same as it does from the ground, except that you would have a much sharper image - the sun would contrast much more on the black background of space. You would see the stars much more clearly than at night as viewed from the ground. The sun would be surrounded by the faint glow imparted by solar radiation. Plasmic Physics (talk) 13:10, 12 October 2011 (UTC)

I'm not so sure about the scarring. The atmosphere on a clear day only reduces luminous intensity by about 30%. So, I would suggest that the effects and perceptions of looking at the sun from space are likely to be pretty similar to glancing at the sun from Earth on a clear day. In other words, temporarily blinding and painful with afterimages, but that the instinct would still be to close your eyes and look away before doing permanent damage. (Thankfully brief glances of the sun cause no permanent damage, or everyone who works outside would be blind by now.) Yes there is a broader spectrum in unfiltered sunlight, but there isn't much total power in x-rays and such compared to visible light, and I would be surprised if that makes any difference in the brief interval before one would close your eyes and look away. I agree that the sun would appear as a sharper image on a black background. If you block out the sun (so your eyes can adjust to darker seeing conditions), then one should be able to see stars whose position in the sky is not too far from the sun. Dragons flight (talk) 16:15, 12 October 2011 (UTC)

Here is a photo although it shows a lot of lens flare which is an artefact of the camera lens. --Colapeninsula (talk) 16:19, 12 October 2011 (UTC)

The colour will also be slightly different. Seen through the atmosphere, a lot of the blue light is removed by Rayleigh scattering (and makes the rest of the sky blue). That's not the case in space. That should make the sun whiter, rather than it being slightly yellow as it is through the atmosphere. The yellowness isn't really noticeable, though, since it's too bright - it's like an overexposed photograph, it just appears white - so you wouldn't really tell the difference with the naked eye, you would need a spectrograph. --Tango (talk) 20:00, 12 October 2011 (UTC)

Water on Earth and the physical properties of water in ocean

Garrison writes that "much more water is trapped within Earth's hot interior than exists in its ocean and atmosphere". Where is this water (in mantle?) and how much of it is there? Also, he gives some figures such as average depth of ocean to be 3796 m, average temp. of seawater to be 3.9 deg. celcius and mass of ocean 1.41 billion billion metric tons. How do scientists manage to figure out the average depth (by mapping the whole sea floor?), temp and mass (which will be a function of salinity)? Thanks. - DSachan (talk) 13:17, 12 October 2011 (UTC)

I would say that average depth is a function of volume, and surface area, once you know those two things you're set. Volume is based on density and mass. Plasmic Physics (talk) 13:28, 12 October 2011 (UTC)

NOAA has mapped the entire sea floor for depth at low resolution (at least 1 data point per 4 square nautical miles), which would be sufficient for a pretty good estimate. Googlemeister (talk) 14:20, 12 October 2011 (UTC)

Right, you can see it all using Google Earth. Regarding the mantle, the water is essentially dissolved in the rock. Looie496 (talk) 14:42, 12 October 2011 (UTC)

"Dissolved" is in the ballpark, but it isn't the exact right term. The water is part of rocks as Water of crystallization. See especially the article Mineral hydration, which deals mostly with crustal minerals, but the chemistry should work in any rock... --Jayron32 15:20, 12 October 2011 (UTC)

If the OP is interested in how satellite altimetry is used to build the predicted water depth datasets, NOAA have quite a nice page here explaining the technique. We also have an article about GEBCO who generate the "GEBCO_08 Grid" bathymetric dataset at 30arc-second intervals. Sean.hoyland - talk 17:05, 12 October 2011 (UTC)

Species identifcation (flower)

Tulip for identification

To aid a rename request, is the specfic tulip concerned identifiable in the image linked? Sfan00 IMG (talk) 20:31, 12 October 2011 (UTC)

Possibly Tulipa praestans 'Fusilier'?-- Obsidi♠n Soul 01:14, 13 October 2011 (UTC)

I added "flower" to the title to distinguish from your other "Species identification" questions (but I kept your typo in). StuRat (talk) 14:41, 13 October 2011 (UTC)

Can a Chihuahua survive in the wild?

Topic says it all. ScienceApe (talk) 16:05, 12 October 2011 (UTC)

It would depend where. A chihuahua would have to scavenge for food rather than hunting: it could eat carrion and whatever else it could find (roadkill, other animals' leftovers, food from bins, food left for other pets). It would be vulnerable to larger carnivores, if there were any - foxes are reportedly unlikely to kill even small dogs, but wolves or bears could. If there was a good food source (maybe in a city) and no larger carnivores it could survive for a while, but in less hospitable environments it would be in trouble. I'm not sure how it would fare in winter, but cold would certainly be a problem. --Colapeninsula (talk) 16:28, 12 October 2011 (UTC)

I read a Scientific American article that said that if all humans disappeared, then dogs would have some chance, but it was basically how close to a wolf they remained (a number of other pets, like cats, would apparently not survive past human food sources going). I don't think a Chihuahua ranks highly on the "wolf" scale. Grandiose (me, talk, contribs) 16:48, 12 October 2011 (UTC)

Life After People is the National Geographic speculation on what would happen over the decades. Comet Tuttle (talk) 17:04, 12 October 2011 (UTC)

I don't know why it couldn't hunt - it could hunt and kill small rodents. It would probably survive on a combination of hunting and scavenging, like wild dogs and wolves do. thx1138 (talk) 17:53, 12 October 2011 (UTC)

Dingos are basically stray dogs that have learned to live in the wild and survived for 100's of generations, so they are pretty strong evidence that at least some dogs could survive without humans. I expect a lot of pets would die, but it only takes a few to survive to be able to keep the species going - I'm sure a few cats would be able to cope, strays aren't that uncommon and they don't just rely on humans leaving out food for them. --Tango (talk) 20:05, 12 October 2011 (UTC)

• Dingos, which are pretty close to wolves, are a far cry away from chihuahuas. Quest09 (talk) 16:24, 13 October 2011 (UTC)

See esp. feral cat, feral dog. I suspect chihuahuas would be at a particular disadvantage, though, given their tiny size and their not too great reputation for smarts. Like many dogs at the extremes, they are heavily inbred and have a number of very disadvantageous features. --Mr.98 (talk) 21:53, 12 October 2011 (UTC)

I'd agree with Mr. 98 and say that chihuahuas would have little chance without being fed by humans. In a situation where pet dogs where forced to fend for themselves in a depopulated city, chihuahuas would be out competed by smarter larger dogs (even large and intelligent breeds would probably struggle to survive). If you just put a chihuahua out in the woods where no one would take it in it would certainly die. They don't have much of a hunting instinct and in the natural environment there are already predators well adapted to most niches who wouldn't leave much for a lone chihuahua. --Daniel 22:08, 12 October 2011 (UTC)

Just as an illustration, chihuahuas and house cats are probably in about the same size/prey class. My money would be on the house cats to win in that little evolutionary niche competition. (There are also gobs more house cats than chihuahuas, so they'd have an early advantage.) --Mr.98 (talk) 11:54, 13 October 2011 (UTC)

One point that all seem to be missing is that dogs can form packs. The question is if chihuahuas would be accepted in one with other, bigger dogs and in what kind of wild environment would this pack have to survive. Quest09 (talk) 12:29, 13 October 2011 (UTC)

Electron configurations

I'm doing a WebAssign homework assignment for chemistry, and on a question asking me to write electron configurations for ions it says that "[Ar] 4s² 3d⁶" for Ni²⁺ and "[Ar] 4s² 3d⁷" for Cu²⁺ are wrong. These are what my chemistry book says the electron configurations for two less electrons than Nickel and Copper are, so I'm completely lost as to why it's saying they're wrong. Any help? Ks0stm ^{(T•C•G•E)} 19:58, 12 October 2011 (UTC)

We have a fairly detailed electron configuration article, including a section entitled "Ionization of the transition metals" that may be of interest. DMacks (talk) 20:32, 12 October 2011 (UTC)

That fixed it. I didn't think to look in the electron configuration article for such specific information; I was looking in the elements' articles. Thanks, Ks0stm ^{(T•C•G•E)} 20:46, 12 October 2011 (UTC)

Species identification (beetle)

Unidentified beetle

To aid a rename request, anyone able to identify the species concerned? Sfan00 IMG (talk) 20:21, 12 October 2011 (UTC)

I know location is often a good way to narrow things down. Do you know where this beetle was photographed? Googlemeister (talk) 20:35, 12 October 2011 (UTC)

"This is an unknown beetle photo taken in Fort Mill, South Carolina."" from the image description Sfan00 IMG (talk) 20:42, 12 October 2011 (UTC)

Most likely Cotinis nitida, which is common and easily found in the area. SemanticMantis (talk) 21:02, 12 October 2011 (UTC)

I added "beetle" to the title to distinguish from your other "Species identification" questions. StuRat (talk) 14:53, 13 October 2011 (UTC)

October 13

Why are multiple personalities a disorder?

Why is displaying multiple personalities considered a mental illness and called dissociative identity disorder? Couldn't it sometimes be advantageous not to always suffer the weaknesses of one's normal personality? (Just think how many more scientists, engineers etc. would be getting laid, if they had a second more extroverted personality.) NeonMerlin 03:37, 13 October 2011 (UTC)

That's not really the way it works, look at the signs and symptoms section. Someone who displayed two perfectly functioning personalities (if that's even possible) would not be diagnosed with a this disorder. Vespine (talk) 03:57, 13 October 2011 (UTC)

If it's not a "disorder", this implies that they have perfect control over them. If so, they are seperate "roles", which healthy people manage to call upon when needed. To use your example, this keeps the scientist from humping his lab assistant mid-experiment or pulling out some test tubes to do research mid-date. StuRat (talk) 14:24, 13 October 2011 (UTC)

See alter ego. Dualus (talk) 18:38, 13 October 2011 (UTC)

Microwave oven safety

I just got a new microwave oven. In a fairly prominent place among the ten pages of warnings was "Install the microwave oven at least 36 inches above the floor". If, instead, I install it on a thirty-inch-high counter, what's going to happen? --Carnildo (talk) 04:01, 13 October 2011 (UTC)

You could test it and see what happens. It's doubtful anything bad will happen. Of course I could be wrong. However, I am fairly certain that my dorm room's microwave is either that high or lower and nothing bad has happened... yet. :p Anyone know differently? Sir William Matthew Flinders Petrie | ^{Say Shalom!} 15 Tishrei 5772 04:17, 13 October 2011 (UTC)

Maybe [7] or [8]? PrimeHunter (talk) 04:29, 13 October 2011 (UTC)

And what child that could reach that far up could actually fit into the microwave? (I've seen some big microwaves, but none that big) Sir William Matthew Flinders Petrie | ^{Say Shalom!} 15 Tishrei 5772 04:32, 13 October 2011 (UTC)

I googled [microwave safety 3 feet], and this US government site appeared:[9] They don't explicitly discuss the 3 foot height, but they do mention a 3-foot "kid-free zone" around grills, and they also talk about various microwave issues. This site,[10] which is generally skeptical about microwave ovens, mentions 3 feet as a reasonably safe distance to keep from the oven. As I skim the various items that google displays, there seems to be something "magical" about 3 feet. Maybe there's a risk of fire if it's too close to the floor? Anecdotally, my oven has sat about 2 1/2 feet of the floor for years, with no apparent issues. Further research may be needed. ←Baseball Bugs ^{What's up, Doc?} carrots→ 05:28, 13 October 2011 (UTC)

Could be an old wive's tale from early in the microwave oven's history. It could be similar to the whole idea of cell phones blowing up gas stations where someone makes up some idea, it becomes a rumor and then an accepted idea. Any Mythbusters episode to disprove whatever idea there is on this one though? :p Sir William Matthew Flinders Petrie | ^{Say Shalom!} 15 Tishrei 5772 05:35, 13 October 2011 (UTC)

Googling the more general [microwave safety minimum height] also yields a number of ideas, including this,[11] which suggests that the 3 foot rule is really more for adults. Also, there's a recurrent theme that the oven should not only not be too low, but also not too high, simply for optimal safety when cooking and when taking stuff out of it. ←Baseball Bugs ^{What's up, Doc?} carrots→ 06:03, 13 October 2011 (UTC)

The door latch switch can fail or be damaged which risks kids getting nuked if the unit is installed too low ("nuke" is slang for cooking with the microwaves lest anyone new here needs to know that,;-)). I would know this unfortunate failure from personal experience too, because a few years ago my microwave oven was still running after I opened the door and was reaching in for my food! Thus I inadvertently cooked my arm briefly. I had to unplug the unit to get it to stop and my arm was sore for several days. I reported the failure to the safety regulators, who should know more about this issue. --Modocc (talk) 07:49, 13 October 2011 (UTC)

I think that it is very unusual for that to happen really. Sore? That is because the water molecules in your arm were vibrating faster. If you had left it there, your arm's muscle probably would have literally exploded off (not sure what would happen to the bone.). Then you would have had only one arm left to attempt to clean up before you bled to death. On the bright side though, Darwin Award. ;) Sir William Matthew Flinders Petrie | ^{Say Shalom!} 15 Tishrei 5772 16:41, 13 October 2011 (UTC)

That's one safety device I feel no need to disable. (One which I do disable is the washing machine not running with the door open. I'm perfectly capable of tossing socks into a running top-loader without tearing my arm off, thank you very much.) StuRat (talk) 14:19, 13 October 2011 (UTC)

I always figured that washing machine feature was more to prevent water from spraying everywhere if you opened it at the wrong time more then worrying about the device mutilating me. Googlemeister (talk) 15:17, 13 October 2011 (UTC)

Not in my machine, at least. The lip on the top of the drum prevents water from spraying out of the top during a spin, since from there it would drip down through the housing onto the floor, in any case. StuRat (talk) 17:35, 13 October 2011 (UTC)

Chemical formulae: technical term for subscripted numerals

For quite some time, I have been trying to learn the technical term for such subscripted numerals as the "2" in "H₂O". Would love to know! I'm expecting something like "atomic ratio subscripts", but somebody in chemical tipesetting must know. It's beginning to appear that they have never been given names. (I'm upset by the recent tendency to type them in-line (non-subscripted), now that it's so easy to subscript, but, that's another matter.) Many thanks for considering this! Nikevich (talk) 07:37, 13 October 2011 (UTC)

For seven years I've been using them now, even so I don't remember ever being taught that it had a name. Plasmic Physics (talk) 12:15, 13 October 2011 (UTC)

Chemical symbol refers to them as "right subscripts" to distinguish them from the atomic number rarely included as a left subscript. Thincat (talk) 18:50, 13 October 2011 (UTC)

Collapsible earth embankment

A car hits a 2 m tall, 2 m wide grass-covered earth embankment head-on at motorway speed. Will all the passengers be killed? If the embankment is filled with collapsible plastic "basketballs", with holes for the air to squeeze out of on impact, how will the impact be different? What if the air is replaced with water? How much pressure would it take to crush such a ball? — Preceding unsigned comment added by 140.203.240.23 (talk) 07:59, 13 October 2011 (UTC)

And, 20 million years from now, when the meerkat people of the future dig the earth of the northern hemisphere, their archaeologists will comment, "No wonder the hairless chimps died out, spending all their time in a bizarre religious ceremony turning the landscape into a nest of sterile plastic eggs." μηδείς (talk) 11:49, 13 October 2011 (UTC)

...but why are the eggs only around Galway? they'll ask. Seriously, there are way too many variables to make a reasonable answer. What thickness of soil on the embankment? how big are the balls? is the soil wet or dry? what is the angle of slope on the embankment? how do you keep water in a ball with holes in it? Richard Avery (talk) 13:22, 13 October 2011 (UTC)

I believe water is usually the best choice, as it has the density required to decelerate the car, but is able to flow out of the way (although you may need to add anti-freeze so it doesn't become ice in winter). This is often used in construction zones, etc. :[12]. Note that no holes are neeeded, as the impact will rupture the container. An alternative, used in runaway truck ramps, is a pile of sand. This, however, requires much more room. StuRat (talk) 14:35, 13 October 2011 (UTC)

Is it true that a normally healthy person can get cancer from the normal background radiation on this planet?

Topic says it all. ScienceApe (talk) 13:13, 13 October 2011 (UTC)

See background radiation. It specifically discusses cancer caused by naturally occurring radon. -- kainaw™ 13:18, 13 October 2011 (UTC)

One can, yes. But that's not a very good way to think about cancer. A better approach is to think about risk factors. Getting cancer is probabilistic: it isn't an issue of, "if you smoke, you'll get cancer" or "if you're exposed to radon, you'll get cancer." It's more like, "if a given population of people smoke, X% of them will get lung cancer, as compared to people who don't smoke." Same with radon. The percentages change a lot, and can be compounding (your chance of getting cancer is a LOT higher if you both smoke AND are exposed to high amounts of radon — in that case, they are synergistic, because the smoking helps deposit the radon into the lungs, or something like that). So, long story short, yes, background radiation factors into your total cancer risk profile. This is useful to know for some types of comparisons, but is less useful for others. It's useful when considering the hazards brought about by living near nuclear plants, for example: in general, these are a lot less than the hazards presented by background radiation. It's less useful when thinking about, say, cigarettes or toxic chemicals, which are not only very different types of exposure paths, but are way above the background level of radiation. One of the tricky things about cancer is that you generally cannot say, "this cancer was for sure caused by this exposure." It's probabilistic, again: something tipped off the cell and made it start going haywire. You can say, "these kinds of cancers are highly correlated with these kinds of exposures," but that's as close as it gets. (That's close enough for the courts in most cases.) So when a "normally healthy person" does get cancer, it isn't necessarily the case that background radiation is at fault; it's not necessarily clear what exposure (if any!) is at fault. --Mr.98 (talk) 14:59, 13 October 2011 (UTC)

Something else to keep in mind is that everyone has cancerous cells all the time. Normally our immune systems destroy the cancer cells before they spread, and that's the end of it. The real question, then, is if background radiation can impair the body's normal immune response, and thus cause what we call "cancer". In this context, background radiation seems like less of a risk than, say, a poor diet. StuRat (talk) 17:28, 13 October 2011 (UTC)

Also remember that according to California Proposition 65, pretty much anything and everything can give you cancer. Sir William Matthew Flinders Petrie | ^{Say Shalom!} 15 Tishrei 5772 17:56, 13 October 2011 (UTC)

StuRat, that's really not an accurate description. Most people don't have cancer cells, and our immune system isn't the primary thing preventing cancer. A cancer cell is one that has been damaged in such a way that it has lost the internal controls that limit uncontrolled growth. The most important such controls are a series of mechanisms that detect cellular DNA damage and trigger apoptosis (i.e. cell suicide) to prevent the cell from accumulating enough damage to actually become cancerous. A cell wouldn't be classed as cancerous until all the internal constrains on cell proliferation have been lost which requires multiple unfortunate mutations to have occurred in the same cell line. The immune system can play a role in controlling the growth and spread of cancer, but it usually doesn't get involved until uncontrolled growth has already started (if ever), and when it does get involved it can sometimes do nearly as much harm as good by taking out both healthy and cancerous cells due to the difficulty in distinguishing the two (e.g. paraneoplastic syndrome). Dragons flight (talk) 18:30, 13 October 2011 (UTC)

I disagree. Take the case of the bubble boy, David Vetter. He had no sign of cancer, and either did his sister. He got a bone marrow transplant from her, and, due to his lack of immune system, he quickly developed hundreds of cancerous tumors from the dormant Epstein Barr virus she carried, and died. She likely had many cancerous cells herself, due to the virus, but they were wiped out by her immune system before they were noticed. I supposed you can define cancer as "tumors large enough that we notice them", but this seems rather silly. If such a tumor developed from a single mutant cell, which is genetically identical to the cells in the later tumor, on what basis is that cell called non-cancerous while they are called cancerous ? If one of the tumor's cells breaks off and floats away, is it then no longer considered cancerous until it reproduces enough to form a noticeable tumor again ?

For another example, AIDS often results in types of cancer which are normally rare. Is HIV causing those cancers directly ? Doubtful. More likely they are there all the time, but aren't a threat until the immune system is compromised. StuRat (talk) 18:47, 13 October 2011 (UTC)

Species Identifcation

unidentified species

To aid a rename request what is this? Location of up loader would seem to suggest this is from somewhere in California. Sfan00 IMG (talk) 13:54, 13 October 2011 (UTC)

I added a CLEAR tag to prevent pic from running into next Q. StuRat (talk) 14:11, 13 October 2011 (UTC)

I think this is probably hopeless. That looks more than anything like a hugely magnified picture of hairs on an insect's abdomen, but it could be spines on a plant or seed -- who knows? By the way, I hope you are not going to be bringing these sorts of random identification questions here very often. If there is reason to think that a picture has some value, that's fine, but mere renaming of random blurry pictures is not a useful way for us to spend our time. Looie496 (talk) 15:49, 13 October 2011 (UTC)

The original uploader seems to be a troll. The picture and his userpage (and blanking a copyright warning) are his only edits-- Obsidi♠n Soul 15:57, 13 October 2011 (UTC)

How about, Wikipedia is not your image host? In general, such images should be recommended for for speedy deletion. They have no encyclopedic merit; Wikipedia doesn't need them. Nimur (talk) 17:22, 13 October 2011 (UTC)

Bucket brigade efficiency ?

I've often wondered if this technique is better than each person just carrying the item in question from the source to the destination directly. Here are some advantages and disadvantages I see to the bucket brigade:

ADVANTAGES

A1) Less mass is moved, since the people themselves don't need to move. This might be particularly important over hilly terrain.

A2) Might work better where insufficent room exists for two columns of people to pass each other, like in a mine.

DISADVANTAGES

D1) Dropping the items seems more likely, especially if the people are far enough apart that they need to toss the objects.

D2) Injury seems more likely, especially if the people are far enough apart that they need to toss the objects. Paula Deen having been smashed in the face with a ham is a prime example: [13].

D3) Would seem to suffer from the "weakest link" problem. For example, if it's necessary to include children to make the human chain reach the target, then the chain can't handle any object heavier than the weakest child can lift.

So, with all this in mind, has anyone proven that a bucket brigade is able to move more items in the same amount of time, or is it just done to foster a spirit of teamwork ? StuRat (talk) 14:09, 13 October 2011 (UTC)

Realistically, I doubt two columns of people can pass each other in the doorway leading to a house fire or a collapsed warehouse, either. I think that the tendency to form a bucket brigade at such obstacles is almost instinctive - when you're holding a full bucket, and you can't go forward around the next person, what do you do? Wnt (talk) 17:15, 13 October 2011 (UTC)

There's also the advantage that a single person may not be able to carry the weight the full distance but can move the weight from one side of their body to the other. Dismas|^(talk) 18:53, 13 October 2011 (UTC)

Online obituary

How can I see The Times online obituary Geoff Handbury or Helen Handbury? I am keen to know the names of each of their 14 grand children. Kittybrewster ☎ 15:16, 13 October 2011 (UTC)

It's behind a paywall, isn't it? Whereabouts are you? You may be able to see it free at a library. --TammyMoet (talk) 15:20, 13 October 2011 (UTC)

Don't assume a newspaper paywall is impassable. A local paper near me sends non-subscribers away with a message that doesn't work if you are running NoScript. The New York Times will tell you an article is subscriber only, but in the past I've taken the same URL, copied it into Google, clicked on the top hit, presto! I'm in. They like Google searchers for some reason. Deleting cookies may get around access limits (plus allow you to vote many times in computer polls - I remember one time the local paper ran a question about whether computerized voting could be hacked. I say they asked for it... ;) Wnt (talk) 17:11, 13 October 2011 (UTC)

Astrologist Claims

Anyone here have an example of an astrologist who claims astrology is science (and claims to be a scientist). Thank you. Wekn reven i susej eht ^{Talk• Follow} 15:37, 13 October 2011 (UTC)

Jaipal Singh Datta apparently does (one of his websites). --Colapeninsula (talk) 16:39, 13 October 2011 (UTC)

RBC Indices

Hello. Why is the mean corpuscular volume multiplied by a factor of 10 and the mean corpuscular haemoglobin concentration by 100? Thanks in advance. --Mayfare (talk) 16:36, 13 October 2011 (UTC)

Not sure of the context, but it's probably a matter of how the values are traditionally written. I know h(a)emoglobin is typically written in grams per deciliter, so there's an obvious multiple of ten. In practice, most clinical laboratory data is discussed without the units because the users are all familiar with the expected units. If for some odd reason what you're looking at is using nonstandard units you'd have to multiply it to convert it to the "standard" units. SDY (talk) 16:59, 13 October 2011 (UTC)

What kind of snake is this? (US Rockies region)

See image. Larger than a Garter snake. Chillin' on a trail up in Colorado foothills, just west of Denver. I think it was in digesting mode because the middle of it looked fatter and nothing seemed to bother it. Image link: [14]. Thanks! Theesotericniffler (talk) 17:53, 13 October 2011 (UTC)

Of the striped snakes native to Colorado, this looks to me most like a Western Terrestrial Garter Snake. Deor (talk) 18:20, 13 October 2011 (UTC)

Household Bleach

Hi, I just used around a 50/50 mixture of water and Clorox brand household Bleach to clean my kitchen floor. It worked well, but I didn't go back over it with another round of plain water, instead I just let it dry. The floor looks great, but is slightly sticky to touch. My question is simply if there is any danger of burns to the skin hours from now, if someone walks over the floor with bare feet. Keep in mind, the floor is totally dry now. Also, what if I spill a small amount of water on the floor later today or two days from now, and then come in contact with it. Will it cause any adverse effects, such as bleaching out nearby carpet if it comes in contact, or has the Sodium hypochlorite already broken down at that point? If so, I'll go mop again with water soon. Thanks, 10draftsdeep (talk) 18:43, 13 October 2011 (UTC)

What was your intention with using so much bleach? Just a glug or two (old Scouting term for about a quarter cup, enough for the bottle to go "glug" when pouring) would have sufficed for disinfecting the floor. Dismas|^(talk) 18:49, 13 October 2011 (UTC)

Hi Dismas, I knew I was going heavy on the bleach. My intentions were not so much disinfection but rather making an old worn discolored floor look close to white in color again. Hopefully someone can provide some insight. 10draftsdeep (talk) 18:58, 13 October 2011 (UTC)