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April 21

Bazhin Gap

In the Nanga Parbat there is a high altitude gap/saddle called "Bazhin Gap". What does "Bazhin" refer to? Local dialect? A name of a person? The expression seems to be mentioned for the first time in the 1930ies. Any lead is appreciated. GEEZER^{nil nisi bene} 10:18, 21 April 2014 (UTC)

Probably a person. Note that there is also a "Bazhin Glacier" nearby. Looie496 (talk) 14:06, 21 April 2014 (UTC)

don't put warm food in fridge?

I had some leftovers that I was going to save in the fridge, but my mom says don't do that since they are still warm. I'm supposed to leave them on the counter til they reach room temperature before refrigerating. She says the same thing when we buy warm stuff from the store. What's the issue here? Does the quicker temperature change mess up the food in some way? Does putting the warm stuff (just an unfinished meal, not anything large) in the fridge temporarily warm up the fridge interior enough to speed the spoilage of other food in the fridge? Or is the whole thing just silly? Thanks. 98.207.66.10 (talk) 19:33, 21 April 2014 (UTC)

"Make sure food has cooled down before you put it in the fridge," says Philippa Hudson, senior lecturer in food safety at Bournemouth University.

"If the food is still hot it will raise the temperature in the fridge, which isn't safe as it can promote bacterial growth." [1] 86.146.28.229 (talk) 20:09, 21 April 2014 (UTC)

See also Danger zone (food safety). If you place an overhot item in the fridge, you increase the chance of raising the temperature of all of the other food around it to temperatures that promote unhealthy bacterial growth. --Jayron32 20:12, 21 April 2014 (UTC)

The U.S. Department of Agriculture says "Hot food can be placed directly in the refrigerator or it can be rapidly chilled in an ice or cold water bath before refrigerating."[2] The U.S. Food and Drug Administration says "Leftovers … need to be refrigerated or frozen within two hours … . Despite what some people believe, putting hot food in the refrigerator doesn't harm the appliance."[3] The Washington State Department of Health labels the idea that you shouldn't put hot foods in the fridge a "myth", and says "Hot food can be placed in the refrigerator."[4] Red Act (talk) 20:24, 21 April 2014 (UTC)

I do wonder if there are climate and cultural differences. The stereotype is that Americans have larger, more powerful fridges than Britons: I know that I have watched the temperature in my fridge rise out of the safe zone, when I have overloaded it. And American food safety advice I have seen seems to assume a much warmer environment than British food safety advice: perhaps in line with the jokes about room temperature being laughably unrealistic in British labs. And every bit of American advice which claims it is a myth, that I have seen, also has a note about if you left the food to cool and forgot about it for hours, which perhaps shows the motive for the advice. This would explain why the official governmental advice from the NHS, supported by expert advice, is to allow food to cool before putting it in the fridge, whereas the official governmental advice in America is to not worry about that. 86.146.28.229 (talk) 20:31, 21 April 2014 (UTC)

I'd say it depends. If you have a powerful, almost empty fridge, containing food that doesn't really need refrigeration anyway (like fruit), and the food you want to put in isn't all that hot, but might tend to spoil quickly, then go for it. On the other hand, if it's very hot, doesn't need refrigeration all that much, and you will need to cram it in right next to some foods that really need to be properly refrigerated (like egg salad), and your fridge can barely keep up with what's already in it, then wait. StuRat (talk) 22:57, 21 April 2014 (UTC)

Thanks, I see. At least this identifies the issue, of warm food in the fridge transferring heat to other food. Of course letting the warm food sit outside the fridge probably attracts even more bacteria, but whatever. 98.207.66.10 (talk) 01:09, 22 April 2014 (UTC)

• This really depends on the food and circumstances. Soup in a pot with a lid that forms a seal can be brought to a boil and served, then left on the stove with the lid closed, be removed from heat, and let cool overnight. As long as the lid is not removed and the stock was boiling it is sterile. Leaving out uncovered eggs or dairy to cool is foolish. Bacterial growth is normally most rapid around body temperature. The worst thing to do is to let food sit warm. It's an easy way to get you restaurant shut down. Food should be under 40 or over 140F. If your fridge is from the 1940's a warm pot might be a problem, but letting a newer model run to cool the food is better than kidney failure. μηδείς (talk) 02:53, 22 April 2014 (UTC)

This thread reminds me of fan death. #science people. Putting something hot in the fridge will raise its temperature by .... how much?... versus the fact your food has been at incubating temperature for how much longer?... Actually come to think of it, this seems to be the approach most of europe takes to most problems, so I guess I'm not surprised. Shadowjams (talk) 07:26, 24 April 2014 (UTC)

(Well you Americans with your giant powerful fridges would think that, wouldn't you?) As Jayron, Stu Rat & Medeis say above, it depends on lots of variables, but I always follow the advice not to put very hot food in a small fridge. It's just common sense. Dbfirs 08:01, 24 April 2014 (UTC)

Fan death strikes me as a socially convenient belief. Obviously shutting off fans/air conditioners automatically saves money, energy, and removes unpleasant noise from the environment. Yet for some reason it seems easier for some people to cite a different motivation. Wnt (talk) 01:14, 25 April 2014 (UTC)

Actually, newer model fridges may not be as good in dealing with this problem than older models. The newer models are a lot more energy efficient due to better insulation, but that means that the fridge doesn't run its engine as often as the older models. If you place a hot object in such a newer model fridge then the temperature in the neighborhood of the hot object will rise a lot more before the engine will run. If the engine only runs once every hour, then the heat from the hot object would have had to trigger the thermostat to run the engine, but that means that the stuff in the direct neighborhood of the object will have been heated well above the ideal temperature. In contrast, if you have an inefficient fridge that runs its engine every five minutes, then the heat from the object is irrelevant. There is then a large heat flux from the environment moving into the fridge that is almost constantly being pumped out.

What I do is I place hot objects in the freezing compartment of the fridge for about 15 minutes to cool them down to about 5 C (the time depends on the size of the object). The thermostat of the fridge reacts immediately to anything placed there and it's also well isolated from other stuff in the fridge (I don't use the freezing compartment of the fridge for storage at all). Count Iblis (talk) 17:20, 24 April 2014 (UTC)

Hypoxia

I have read the article on hypoxia, but it did not answer my questions. What are the cumulative effects of marginal hypoxia? What would the main symptoms be? Thank you. — Preceding unsigned comment added by 62.56.71.197 (talk) 21:45, 21 April 2014 (UTC)

I'm not an expert on hypoxia, but I suppose drowsiness and fatigue would be two of the most likely symptoms/effects. FWiW 24.5.122.13 (talk) 05:48, 22 April 2014 (UTC)

Confusion and muddled/slow thinking. It kills pilots because they are awake but unaware of danger or that help is in their interest. --DHeyward (talk) 09:52, 23 April 2014 (UTC)

Kinda like getting really drunk on rum and Cokes -- you don't notice anything wrong until you're totally blasted. 24.5.122.13 (talk) 23:56, 23 April 2014 (UTC)

Cumulative effects of marginal hypoxia? There are no known cumulative effects. When a person receives sufficient oxygen that the blood is again fully oxygenated, the effects of any preceding hypoxia are completely erased. Dolphin (t) 06:19, 25 April 2014 (UTC)

Rust treatment

Steel gasoline (UK: petrol) tanks of cars and motorcycles that have internal rust are difficult to clean, access is only via by small openings and most of the inner surface is out of sight. Vinegar which is mainly dilute Acetic acid is suggested in online videos as a rust remover so I experimented by letting the head of a rusty screw soak overnight in a teaspoonful of concentrated "Vinegar Essence 35%" which is cheap (and is probably safer than an industrial chemical such as phosphoric acid). The pictures show my results which are promising. The questions are:

1. Surface rust on the screw has blossomed into a powdery scale (center pic). This happens above the submerged part of the screw. I suppose capillary action and/or a reaction in air occur. Can anyone explain what chemical reaction is likely here?
2. The converted rust could be washed off with warm water (right pic). The bolt head is now almost rust free, and I can repeat the treatment. But in the case of a fuel tank I suspect the acid etched surface will be prone to rust again quickly. My question is what is a good way to finish the vinegar treatment? I am considering alternatives such as rinsing with Kerosene, Gasoline or with dilute caustic soda ? JustAnotherUploader (talk) 23:50, 21 April 2014 (UTC)

I'm wondering if it makes economic sense to try to remove rust from a gas tank, instead of replacing it. To remove the rust you will have to remove the gas tank (which is quite a job, in the case of a car), drain it, then use quite a bit of whatever rust removing agent you decide on, then rinse that, then coat it with a large quantity of some type of anti-rust treatment, then maybe let it cure for a while, then rinse again, dry all the water out, then re-install. The labor and other costs of all this sounds like it would exceed that of a new tank (or maybe a used one from a junkyard). Perhaps an exception might exist for old tanks for which no replacement can be found, or when you need to keep the original parts intact in a classic vehicle. StuRat (talk) 01:26, 22 April 2014 (UTC)

• I have to agree with Stu. Have a professional replace the tank. The last thing you need is rust particles flowing upstream into the engineworks. Pennywise, poundfoolish. μηδείς (talk) 02:40, 22 April 2014 (UTC)

Yes, I once had a vehicle that had rust in the fuel tank. I had to regularly remove the fuel injectors to clean them. Dbfirs 16:51, 23 April 2014 (UTC)

If you need to do this because its a Classic vehicle its only worth doing properly. I used to own classic cars, so know, that if you don't get all the corrosion off and the new surface properly sealed again the rust comes back real quick. Here's a link with photos. DIY Fuel-tank Rust Removal (by Electrolysis) & Rust Proofing Its a common task to do when renovating old vintage bangers so there must be plenty more examples on the web.--Aspro (talk) 16:55, 23 April 2014 (UTC)

April 22

Which covalent bonds are broken in DNA cleavage by nucleases?

When DNA is cleaved by restriction endonucleases, meganucleases, engineered zinc finger nucleases/TALENs or Cas9 which covalent bonds are broken? Are they different for each type and if so, does that affect the repair mechanisms? --78.148.106.196 (talk) 00:47, 22 April 2014 (UTC)

I suggest you read the first sentence in nuclease, and our article on DNA. There is only one bond to be cleaved in DNA. Fgf10 (talk) 07:08, 22 April 2014 (UTC)

I think I can see five potential bonds that could be cleaved. What makes you so sure that all enzymes cleave cleanly at that point? --78.148.106.196 (talk) 10:58, 22 April 2014 (UTC)

Only likely (from a chemical standpoint) possibilities, given we are talking about the phosphodiester bonds of the backbone linkage, are the two P–O (those O being the 3' and 5' on the adjacent deoxyribose parts of the two DNA residues). The two O–C are comparatively harder to break. And the C^5'–C^4' is not at all fragile. The question of "which P–O" is a reasonable one. Assuming the phosphate remains attached to one of the two DNA residues, does it stay with 3' (breaking off the next one's 5') or vice versa? DMacks (talk) 14:56, 22 April 2014 (UTC)

I think it's going to be a while before I can answer my own question. I know that some of the enzymes form covalent bonds with the DNA which are then broken. Also, since the restriction endonucleases, Cas9 and the business ends of ZFNs and TALENs all derive from an evolutionary need to protect bacteria from invading phage and plasmids, I think it stands to reason that the DNA might be cleaved in such a way that it couldn't easily be ligated back together. I don't know nearly as much as I'd like to about DNA repair. Some day... 78.148.106.196 (talk) 19:46, 22 April 2014 (UTC)

For "which side", the answer depends on the nuclease. For example, there's Deoxyribonuclease I which cleaves such that it leaves a 5'-phosphate, and Deoxyribonuclease II, which cleaves such that it leaves a 3'-phosphate. For most restriction endonucleases (and things like zinc finger nucleases, which have their catalytic domain derived from restriction endonucleases like FokI), they typically cleave the bond so as to leave a 5'-phosphate. (For example, Meganuclease I-SceI notes that it leaves a 3' hydroxyl.) This leaves things set up such that DNA ligase can repair the break by joining the 5'-phosphate with a 3' hydroxyl. (Note that leaving a 3' hydroxyl is important if you need to continue the chain via polymerases, which use the 3' hydroxyl to displace the pyrophosphate on the NTP.) -- 160.129.138.186 (talk) 23:28, 23 April 2014 (UTC)

Rotary cannon and super capacitors

The M61 Vulcan compared to the Gryazev-Shipunov GSh-6-23 has a slower rate of fire and has a slower "spin up" time. The article says this is due to the GSh-6-23 using a gas operating system instead of an electrical system to cycle the weapon. I was wondering if a rotary cannon were powered by super capacitors, would they have more power, and therefore spin up faster and have a rate of fire comparable to the gas operating rotary cannon? Also on a related note, would super capacitors grant electric cars greater acceleration? ScienceApe (talk) 00:59, 22 April 2014 (UTC)

My guess is that you are not on the right track. The reason the electrical system would be "slower" I doubt is because of the power delivery, which is probably from the vehicle. It seem far more likely to me that it is a synchronization or motor speed issue, there’s also heat dissipation and many other factors to consider. These guns are designed with many specifications in mind, including weight, cost and serviceability, not just “rate of fire”. No doubt you COULD make a faster firing, electrically powered rotary cannon, could you do it with super capacitors? I don’t really see why you’d bother, there are perfectly serviceable high speed motors, I don’t think power delivery is the limiting factor there. As for cars, power delivery ‘’might’’ be a factor, but no doubt weight and cost are also, and I don’t think electric cars have a problem with acceleration, the major problem for electric cars is range, so weight plays a more important factor. Vespine (talk) 02:17, 22 April 2014 (UTC)

Have a read of the applications section of the Supercapacitor article, if you haven't already. You'll get a good idea of the kinds of situations supercapacitors are being used in, they generally supplement systems where batteries are already used or only small amounts of power are required. They might be used in electric cars, but it would be more to save the batteries from spikes in current drain which could reduce their (usually expensive) life, rather then to "supercharge" the acceleration or anything like that. Vespine (talk) 02:24, 22 April 2014 (UTC)

Right, as for electric cars, I would guess that the acceleration is actually limited by the computer to act more like a traditional gas-powered car. In a conventional internal combustion engine, torque increases with engine RPM and will eventually decrease at even higher RPMs (see Power band), hence the need for transmissions with multiple gear ratios. This isn't the case with electric motors. Electric motors can produce maximum torque instantly. So the actual acceleration is probably limited to keep people from doing a burnout every time they tap the accelerator. Though they certainly can if you want, the Tesla Model S has a 0-60 time of ~4 seconds, comparable to a Corvette. And then there's the EV-converted 1972 Datsun that can do it under 2 seconds, comparable to an F1 car.

Another benefit to using supercapacitors in vehicles though is their short charge time. They can be fully charged in minutes rather than hours. So for vehicles that stop a lot at predictable locations for short periods of time like buses, you can build electric vehicles that can run all day without needing continuous overhead wires like a trolleybus. Mr.Z-man 03:34, 22 April 2014 (UTC)

Why does the gas operated rotary canon fire faster/faster spin up time? Isn't it because the propellant produces more power? ScienceApe (talk) 01:49, 23 April 2014 (UTC)

To touch the gun part of the question, there are newer Vulcan cannon which have both an increased ROF and shorter spin-up interval; they achieve that through decreased spun mass rather than better motors (or a Tim Taylor-esque "more power" approach). Other guns (including the XM301, no image though) feature a truncated-conic (rather than cylindric) barrel array, where the muzzles are at the narrow end. This does not only (slightly) decrease spun mass, but it limits the energy taken to spin the array, because a lower linear velocity will translate to the same angular velocity. The fact that the muzzle velocity vector and the axis are no longer parallel is accounted for easily.

During live-fire exercises, many guns are used at a low speed setting (usually half or two thirds of battle speed), and fed training rounds, which are not only cheaper than fully combat-effective rounds, but also easier on the barrels. - ¡Ouch! (^{hurt me} / _{more pain}) 06:59, 22 April 2014 (UTC)

Most modern gatling guns operate using a DC motor to cycle the rounds (chambering, ejecting, etc.) A typical time frame for the gatling gun to reach full fire rate is about 0.4 seconds (see GAU-19). So the super capacitor idea is kind of a moot point. Justin15w (talk) 15:30, 22 April 2014 (UTC)

This page states about the Soviet GSh-6-30 that

The charging and spin-up of the barrel group before firing was achieved with the use of a pneumatic system which included, among other things, a pair of compressed air storage tanks and a "pneumostarter".

From the same author, we get spin-up times of about 0.4s for both the older M61 Vulcan and its bigger cousin the GAU-12, while the GSh times are merely given as "far less". The newer M61A2 is stated to have an improved spin-up of 0.25 seconds.

Currently, rotary cannon seem to come in roughly five sizes.

• 5.56mm, based on the 5.56mm NATO round, the 5.45mm Soviet, or the .22 Long Rifle. These are of very limited use due to their short range.
• 7.62mm (NATO or Soviet). These are heavy machineguns in terms of raw firepower but not WRT range. However, the sheer volume of fire does help achieve kills at ranges which wouldn't be called "effective" for single-barrel machineguns.
• 12.7mm MG (again, NATO or Soviet). These are the true heavy machineguns, usually found on the heavier vehicles, or as small guns on ships or attack helicopters.
• 20 to 23mm. Most of these cannon are mounted on fighter planes or air defense platforms. The CIWS role is notable, too. Spin-up is critical in the dogfighting role, and only there. In the CIWS role, the ROF is usually stepped down on purpose, because the full volume of shells would not outweigh the lower accuracy, except at very close range.
• 25mm and more. Old high-caliber guns are usually in the 30+ range, while most newer guns use 25mm shells with little to no loss of effectiveness. Roles are the same as the 20mm class, but better suited to overcome the low hit probabilities on maneuvering targets with a more damaging round. As noted above, the spin-up time is comparable to older 20mm weapons, but the GAUs are probably still behind the Soviet GShs. - ¡Ouch! (^{hurt me} / _{more pain}) 07:58, 23 April 2014 (UTC)

There are at least two larger calibers. The 30mm GAU-8/A_Avenger and the 37mm T249 Vigilante, although the latter never saw full production. ScienceApe (talk) 20:52, 23 April 2014 (UTC)

Technically, those two are in the "25mm and more" class, in the "30+ range" to be precise. ;) But thanks for providing the links.

According to the article, the Vigilante "had a 192-round drum magazine, which in the 3,000 rpm mode would have equated to approximately 5 seconds of fire", which indicates a really long spin-up (~2 seconds). - ¡Ouch! (^{hurt me} / _{more pain}) 05:51, 24 April 2014 (UTC)

Mesopotamian units of measure

Dear refence desk

please supply the reference for two specific Sumerian units which are given with precision

first the cubit (kus) of 497 mm

second the mass of the pound (ma-na) of 497.7 grams

Thank you

Roland Boucher Irvine california — Preceding unsigned comment added by 2602:306:CE07:A6D0:21F:F3FF:FECE:3122 (talk) 03:14, 22 April 2014 (UTC)

You already asked here three months ago for support for the cubit being 497mm, which I'm aware that you need to be true in order to support your theory (that I won't link to) that the Sumerians basically invented the metric system 5000 years before the French proposed it. The information you were given last time, that in historical reality the cubit wasn't a precise consistent length but rather varied a bit depending on the precise time and location you're talking about, is still true. Red Act (talk) 05:43, 22 April 2014 (UTC)

It's also important to understand (and accept) that the levels of precision you're expecting did not exist in those days, even in places and timeframes where the units employed were consistent. AlexTiefling (talk) 12:27, 22 April 2014 (UTC)

Bah! This theory has bogus written all over it!

1. The meter was originally defined as 1/10,000,000th the distance from the pole to the equator - there is no way the Mesopotamians knew the size of the earth to any kind of precision - so it can only be coincidence that their definition of the cubit is remotely close to a half meter.
2. As we've already pointed out, there are countless different standards for the "cubit". Finding one specific place where it just happens to come out within a percent or two of a half meter isn't a great way to come up with a theory. What about all of the other places where it WASN'T close to a half meter?
3. If they had intentionally defined the pound in terms of the cubit in the same manner that the kilogram is defined in terms of the meter (1 kg = the mass of 1 liter of distilled water at 4 degC = 1/1000th of a cubic meter of water at 4 degC), they'd have had to choose a temperature at which to make that definition. The only way for your theory to make sense would be if they (like the French) chose the temperature of 4 degrees Centigrade to measure the density of water. Since Mesopotamia is a fairly hot region of the world, with very few mountains high enough to reach those low temperatures, it seems highly unlikely that they'd have happened to pick the exact same temperature as the French at which to define their system. It's stretching the bounds of plausibility to breaking point to imagine that they'd have done that.
4. If you'd picked a HALF meter as your standard unit of length, then the natural unit of mass would be 1/1000th of a cubic cubit of water. That 'natural' measure would be EIGHT times less than the kilogram - not half a kilogram as you claim they used for their pound. A cubic volume of water weighing 1 meospotamian pound would be some very odd size in mesopotamian cubits...actually, an irrational number.

For all of these reasons, your ideas are very, very busted. The relationships you think you've found are nothing more than a coincidence.

SteveBaker (talk) 02:12, 23 April 2014 (UTC)

Hunger hormones VS Appetite hormones

As I know, it is now clear for scientists that Hunger and Appetite are 2 different things - Hunger will always bring appetite but appetite won't necessarily bring hunger.

My question is: Are there any documented Neurochemicals that deals specifically with hunger and others that specifically with appetite? Thanks Ben-Natan (talk) 04:08, 22 April 2014 (UTC)

I don't think your distinction between Hunger and Appetite is standard in the literature, but if you are using "Appetite" to mean the act of eating, then yes, there are biological distinctions. It isn't true, though, that hunger always causes eating. Unfortunately we don't yet have a very deep understanding of either the neurochemistry of hunger or the mechanisms that drive eating. Our article on hunger (motivational state) gives a rather sketchy overview of what is currently known. The hormones leptin and ghrelin seem to be pretty directly related to the sensation of hunger. Looie496 (talk) 14:02, 22 April 2014 (UTC)

Buoancy

If no water is displaced when an object is put in it, then how do objects like leaves float when they do not displace water and thus the water does not have buoyancy force? — Preceding unsigned comment added by 122.150.66.107 (talk) 04:52, 22 April 2014 (UTC)

Anything that floats on water displaces water. See Archimedes principle. Leaves don't displace very much, because they don't weigh very much. --50.100.193.30 (talk) 05:43, 22 April 2014 (UTC)

Perhaps surface tension has something to do with it. Richard Avery (talk) 05:59, 22 April 2014 (UTC)

Yes, surface tension has two effects: firstly, for an unwetted leaf, it moves the displacement of water away from the leaf (but the same amount of water is still displaced, it's just not as obvious); secondly, at the boundary of the container, it allows displaced water to form a meniscus above the edge of the container, preventing overflow. Thus the displacement of a small mass of water is not clearly observable. The displacement will be more clearly visible if you use heavier leaves and add a surfactant (e.g. detergent) to the water next time you try the experiment. Dbfirs 09:07, 22 April 2014 (UTC)

Giant bumblebee

Here in Central California this spring, there seem to be quite a few GIGANTIC black bumblebees (I'd say at least 1.5-2 inches in length, and about the same in wingspan), which I hadn't noticed in previous years. Are these native to California, or are they an invasive species? Are they any more dangerous than ordinary bumblebees (more aggressive/more toxic/etc.)? Thanks in advance! 24.5.122.13 (talk) 05:54, 22 April 2014 (UTC)

Black bees tend to be Carpenter bees, and there are many species of them. Some can get quite large: see [5]. If I had to guess, you have seen some kind of carpenter bee, but more specific than that, it would be hard to say. --Jayron32 12:40, 22 April 2014 (UTC)

There's also the black-chinned hummingbird there. The ones in our article don't look all that black, but here's one that does: [6], which can be mistaken for a giant bee, as it makes a similar sound and also hovers as it goes from flower to flower. (While in motion, the wings are a blur, so you can't see the obvious difference between bird wings and insect wings.) StuRat (talk) 13:38, 22 April 2014 (UTC)

Without pics it's hard to ID conclusively, but Xylocopa_varipuncta is the largest bee native to California. Females are metallic black, males are gold and fluffy. They can reach over an inch long, and can easily seem to reach 2" while on the wing. In general, actual bumble bees (bombus) are not very aggressive. Carpenter bees can be aggressive, but mostly to other bees. This in part comes from different social structures. Most carpenter bees are solitary, and each male will defend an area from other males, while hoping to attract mates. People often think they are a threat, as they will aggregate around e.g. wooden picnic shelters that they have prepared nesting sites in. The bees will then fly at incoming animals to investigate. So, you might feel threatened if one of these comes flying at your head, it actually poses no threat, it just wants to make sure you're not a rival bee. Males can't sting, and you can swat them away with impunity. For fun, you can wad up a bit of paper or aluminum foil and chuck in the direction of such an aggregation. The bee will quickly track that object, and follow it away from you. Since they don't live together in a large colony, they do not cooperatively defend anything, so it is almost impossible to get a swarm of them chasing you (unlike certain wasps, africanized honeybees, etc.) Anyway, just wanted to give you the general info that carpenter bees are nothing to be afraid of. Yellow jackets, however, are horrible jerks, and will seriously ruin your day ;) SemanticMantis (talk) 15:46, 22 April 2014 (UTC)

Looks like Xylocopa californica to me, because it was not shiny, although the one I saw up close was at least 1.5 inches long. Anyway, from what I gather, they ARE native to California, and the best way to deal with them is to just leave them alone, right? 24.5.122.13 (talk) 22:16, 22 April 2014 (UTC)

Right! The only "problem" they cause if if a whole bunch of them decide to try to nest in the eaves of your house or garage. Even then, mostly just an annoyance, but enough small holes can structurally damage over time (see e.g. here [7]) If you are getting "buzzed" by them often, just ignore, swatting at them may trigger aggression. SemanticMantis (talk) 15:04, 23 April 2014 (UTC)

• Well, first of all, it has been proven that bumblebees can't fly, so you needn't worry these are bumblebees. On the East Coast, I always notice the carpenter bees come out first, then the bumblebees, then the honeybees. Control is easy when necessary, they sell specifically designed insecticide cans with long straight spray streams with which you can easily reach their nests at a distance. There's no need to kill them unless they are excavating the wooden beams of a valued structure. μηδείς (talk) 17:10, 23 April 2014 (UTC)
  • ...Bumblebee#Flight (under "misconceptions"). --— Rhododendrites ^talk |  19:07, 23 April 2014 (UTC)

Do Jews have some African/Black DNA?

All the people that I know are Jewish ethnicity/race have some of the same ethnicity-specific features as Black people including a cloud of big curly hair that grows out like an afro, very full lips and according to a funny book about true stereotypes, a giant penis. Since Jews have some of the features that are unique to African people does that mean they have some African/Black DNA? — Preceding unsigned comment added by 68.8.106.52 (talk) 05:12, April 22, 2014

We all have African DNA. HiLo48 (talk) 09:44, 22 April 2014 (UTC)

More specifically "In paleoanthropology, the recent African origin of modern humans, frequently dubbed the "Out of Africa" theory, is the most widely accepted model describing the geographic origin and early migration of anatomically modern humans." --Jayron32 10:52, 22 April 2014 (UTC)

That's correct, but the "Out of Africa" event occurred over 50,000 years ago. Since then there has been limited genetic mixing between sub-Saharan populations and non-African populations, so the question actually does make some sense at that level. The bigger problem is that there is really no such thing as a "Jewish race", or anything like it, at a biological level. Modern-day Jews derive from a pretty diverse mixture of backgrounds. In any case, as a group, it's extremely unlikely that they have higher levels of sub-Saharan-derived DNA than other people from the same parts of Europe or Asia. (I think the question is probably trolling but I have answered it seriously anyway.) Looie496 (talk) 13:51, 22 April 2014 (UTC)

The question may be related to Ethiopian Jews in Israel. Ruslik_Zero 19:32, 22 April 2014 (UTC)

For the hair bit: obviously not all Africans have the same hair type, nor do all Jewish people. Afro#Similar_styles_internationally has some discussion and references. SemanticMantis (talk) 22:12, 22 April 2014 (UTC)

By African/Black I mean someone the same racial ethnicity as (and this probably sounds offensive but) Flavor Flav. I know about the "Out of Africa" event and that all people are descended from people from the entire continent of Africa. But there are a lot of different types of African-nationality individuals, from this to this to this. But the hair texture of 100% Black people is unique to people of specifically Negro ethnicity (which is maybe what I should have written instead of African). Take the afro or the flat-top for example. Those specific TEXTURES are examples of natural Black hair and no one else on Earth has hair that grows that way, not even if they want it to, unless they have some Negro ancestry I would think. So I would like to get this question answered if you'll give it another try. Looie469, are there any charts or graphs or studies that could prove your view or mine? And I've read before that there is a difference between people who are religiously Jewish and ethnically Jewish. I guess not? — Preceding unsigned comment added by 68.8.106.52 (talk) 23:30, 22 April 2014 (UTC)

That type of hair is known as Afro-textured hair, or sometimes as "nappy hair", and it actually isn't true that only Africans and their descendants have it. As Afro-textured hair#Evolution explains, there are several other populations who live in equatorial regions who have similar hair. Looie496 (talk) 03:42, 23 April 2014 (UTC)

Those articles were very interesting! Thanks for enlightening me. — Preceding unsigned comment added by 68.8.106.52 (talk) 06:11, 23 April 2014 (UTC)

I had never heard of Flavor Flav, so I just checked our article on him. In every photo he's wearing a hat, so I still don't know what his hair looks like, and the article says nothing about his ethnicity. HiLo48 (talk) 06:31, 23 April 2014 (UTC)

Here HiLo, you can see a bit of his hair in this photo: http://images.starpulse.com/pictures/2009/03/22/previews/Flavor%20Flav-PRN-035552.jpg This guy doesn't look Black to you? Well, we're all entitled to our own opinion. Haha. Thanks. — Preceding unsigned comment added by 68.8.106.52 (talk) 07:01, 23 April 2014 (UTC)

Baseline fitness

Other than age, what influences natural baseline fitness levels. Without any training, anyone's fitness regresses but what influences the speed of regression and also where the regression stops, other than age. Clover345 (talk) 10:13, 22 April 2014 (UTC)

Physical fitness is a nebulous concept, and not easily quantifiable. There are aspects of fitness (such as the ability to complete certain physical tasks, like run a certain distance, etc.) or things like Basal metabolic rate or Body Mass Index or other such measures which are sometimes used as proxies for fitness, but none of those singularly captures what it means to be "fit". --Jayron32 12:34, 22 April 2014 (UTC)

Hormone levels are important, in particular testosterone in males. Looie496 (talk) 14:47, 22 April 2014 (UTC)

Physical activity an important factor here. If you exercise regularly from a young age onward, you should not notice a significant decline in physical fitness until you start to hit old age. Only if you are an olympic class top sporter who exercises a few hours per day will this be different. A typical 60 year long distance runner who has run for most of his life can perform just as well as when he was 30; exercising regularly will have helped to preserve the physical fitness he had decades ago. Count Iblis (talk) 15:07, 22 April 2014 (UTC)

Urinalysis

Do chlamydia and gonnorhea urine tests involve the same test as a urinalysis looking for white cells, blood etc? If not, why don't they do it along with the std test since they have a sample of urine anyway sand it can't be that expensive to do both? Do these test literally only detect chlamdia and gonnorhea? 90.205.212.104 (talk) 14:14, 22 April 2014 (UTC)

According to http://std.about.com/od/gettingtested/qt/Urine-Testing-For-Gonorrhea-And-Chlamydia.htm, the standard method of testing is to test for the presence of bacterial DNA in the urine. That's quite different from the method of looking for blood cells. Looie496 (talk) 14:46, 22 April 2014 (UTC)

They could also test for LSD metabolites, gold particles, and Borg nanoprobes. The questions invovled are reasonable suspicion of risk, cost-benefit analysis, and informed consent. μηδείς (talk) 16:57, 22 April 2014 (UTC)

Would borg nano probes and gold particles come out in urine? 90.205.212.104 (talk) 18:27, 22 April 2014 (UTC)

Does (or did) any country's military or police use the Desert Eagle pistol?

Question as topic. I thought at one time that the Israeli military and US Special Forces used them, for two examples - but I've been told not. I have been told that most Desert Eagles will only ever be fired at targets, tin cans and water jugs by private owners, because they're not actually that useful, in terms of effectiveness to the military and police, despite being a .50 caliber pistol. Also that they're basically 'more form than function'. Thanks. — Preceding unsigned comment added by 87.112.139.143 (talk) 21:43, 22 April 2014 (UTC)

This impressively outsized handgun quickly attracted the attention of Hollywood. The Desert Eagle debuted in "The Year of the Dragon," a 1984 action flick staring Mickey Rourke. Since then, it's been featured in some 400 to 500 motion pictures and TV films, including Arnold Schwarzenegger's "Eraser" and "The Last Action Hero." Whenever a script calls for a wicked-looking, thoroughly intimidating handgun, the Desert Eagle still gets the nod - says "American Handgunner". I observed one in the holster of a petite policewoman rushed on duty at Venice Airport hours after transatlantic air transport was shut down following the WTC Attacks. Nella lettura di questa mia cara, mi scusi se glielo dico ciò che difficilmente la si può sollevare solo il look ridicolo. JustAnotherUploader (talk) 22:09, 22 April 2014 (UTC)

The absence of scales in the pictures in our article make it hard to judge its size. DuncanHill (talk) 22:15, 22 April 2014 (UTC)

Demi Moore for scale (?) here [8], from this thread discussing the gun [9]. (I did look around for actual scales or size comparison, but couldn't find anything else that made it look big). SemanticMantis (talk) 23:57, 22 April 2014 (UTC)

With a barrel length of 10-15 inches depending on model, it IS pretty big for a pistol. 24.5.122.13 (talk) 05:34, 23 April 2014 (UTC)

I fired one once, caliber .50 Action Express, and nearly knocked myself over, though I'm a good bit heavier than Demi Moore. In hindsight I wasn't properly braced, but in combat you can't count on that anyway. —Tamfang (talk) 09:23, 23 April 2014 (UTC)

Why are "double red cell" blood donations by females subject to a higher weight requirement?

While looking at the Red Cross blood donation elgibility rules for something else, I noticed here that double red cell donations by females are subject to a higher weight and height requirement than those by males. Why is this the case? I initially thought that this was a mistake, but after some more searching, this doesn't seem to be the case. To me it doesn't make much sense, since one would think that quite a sizeable number of females wouldn't be heavy or tall enough, and given that men are generally taller/heavier. (While perhaps there are many "average" Americans who might fit the requirements, it for instance seems clear to me that from personal experience, this might disqualify a lot of Asian American women.) Morningcrow (talk) — Preceding undated comment added 22:45, 22 April 2014 (UTC)

On average, women have a lower proportion of blood per unit of body weight (in part due to their higher average body fat content) than men. Roughly speaking, men have approximately 75 mL of blood per kilogram of body weight, whereas woman only have about 65 mL per kilogram. Women also average a lower hematocrit (volume fraction of red blood cells in whole blood) than men.

The purpose of the requirements isn't to ensure that equal numbers of men and women are able to donate, but rather to ensure that it is safe for donors to do so. TenOfAllTrades(talk) 22:57, 22 April 2014 (UTC)

I figured it wasn't because of an interest in having equal numbers (otherwise it definitely wouldn't have made sense), but had no idea. Thanks - this more or less explains everything. 23:06, 22 April 2014 (UTC) — Preceding unsigned comment added by Morningcrow (talk • contribs)

Direct current from stored torsion (e.g. wind-up battery/battery charger)

Hi, I'm interested in the general physics and engineering at play here, but I'll put the two specific questions up front:

1. Are there any devices on the market that let you turn a crank to store energy in a spring, and then release that energy slowly to power a small electronic device (or charge a battery)? I'm aware of crank-powered flashlights and and chargers, e.g. [10], but those don't store mechanical power; they seem to universally require high speed, low-resistance turning for long periods of time, even to power a small radio.

2. Assuming negative to the above, are there any physical problems with the idea, or is it more a matter of engineering/materials/market limitations?

Elaboration on the idea: wouldn't it be more convenient to turn a crank with much more resistance, over a shorter period of time, with less dependence on rotation speed? E.g. if I wanted to charge a flashlight with a one-hour charge while camping, I'd rather work to wind a very stiff spring for a minute or so, than spin those little cranks quickly for about 10 minutes, perhaps repeatedly.

I'd think that a torsion spring could be rigged up to drive a small dynamo, and the resulting current could either run a device directly, or charge its battery, or perhaps even both, depending on needs. But then I get a little lost through all the details. Surely there's a lot of linkages, gearing, and other mechanics to worry about. We have to consider current/voltage demands, the spring constants of the material, the size of lever arms and rotors, etc. In summary, is it foolish to think that a device could do this? If not, could something like this be cobbled together from mostly of-the-shelf components? Weight, size and conversion efficiency don't matter much for the last bit, but of course they would for a hypothetical product. Thanks for any suggestions, SemanticMantis (talk) 23:35, 22 April 2014 (UTC)

Compressed air is used to store energy. Count Iblis (talk) 00:38, 23 April 2014 (UTC)

See Human power#Windup radio for a practical example of something that does exactly this. AndyTheGrump (talk) 00:44, 23 April 2014 (UTC)

Ah, thanks! I hadn't heard/seen any specific mention of spring storage before! SemanticMantis (talk)

I have such a wind-up radio. The idea is that it's ready for emergency use, while a battery-powered radio always seems to have dead batteries whenever the emergency occurs, and even if you have spare batteries, acid may have leaked out of the old batteries and destroyed the radio.

I also recall that on the TV show M*A*S*H, Radar O'Reilly would wind up the army phone before using it. StuRat (talk) 11:59, 23 April 2014 (UTC)

I am not 100% certain, but I think the 'winder' was only to signal the other telephone or switchboard. See here, and here which says this type of phone was in use from ≈1937, WW2 through to Korea, and "into the 1980s".--220 of ^Borg 13:47, 23 April 2014 (UTC)

Yes - the phone doesn't have a battery - but the base station does. You wind the crank to produce enough energy to ring the bell at the base station - then they connect you to a battery at their end that provides the power for the duration of the call. SteveBaker (talk) 16:30, 23 April 2014 (UTC)

Steve, many years ago we used old Army surplus field phones WW2 vintage, to talk over pairs of wires as from an electrical substation to an industrial customer's electrical room where there was no land line phone and celphones were not around yet and they were too cheap to give us handheld radios. Each fieldphone had a local battery to power the talk circuit (carbon mic in the handset, battery transformer like old country wall phones). The crank indeed provided the ringing voltage. Phone company phone systems switched to having a battery only at the central station in the early-mid 20th century. The field phones might also work with a central battery. I just know they worked with other field phones with only a copper pair connecting them and that each had a battery. Edison (talk) 20:38, 24 April 2014 (UTC)

Yes. Search for images of the old Freeplay flashlight. I was given one a long time ago, perhaps in the early 1990s, which had a clear plastic case so you could see the mechanism. The handle wound a very wide, substantial spring from one spool to another, taking about 20-30 seconds. When switched on, the spring wound back over a period of about 3 minutes, either operating the light or charging a small NiCd battery. I don't have the bandwidth for any images, but the Freeplay site does have a small support page for their discontinued Freeplay 2020 flashlight, which includes the warning, "The spring is powerful and dangerous. Do not remove any covers unless you are an experienced engineer.", so that sounds like the mechanism I remember. If I ever make it back to my storage unit, I think I will dig it out and look into converting it to LED. -- ToE 12:49, 23 April 2014 (UTC)

Yea, 3 minutes is pretty much useless. With it converted to LED hopefully you can get 10-20 minutes out of it. But how exactly does one convert a flashlight from incandescent to LED ? I have some large flashlights that take 4 D-cells each, and I'd love to convert those to LEDs. StuRat (talk) 16:50, 23 April 2014 (UTC)

If they're Maglites I'm certain they sell drop-in LED replacements for their incandescent bulbs, though can be rather pricey! [11] Some related info here. Googling "led torch conversion kit" got useful hits like Tektite. 220 of ^Borg 00:37, 24 April 2014 (UTC)

Wow. $30 for a single LED bulb ? That's like 10X what I would be willing to pay, and more than the flashlights cost when new. StuRat (talk) 05:08, 25 April 2014 (UTC)

I don't understand the advantages here. I understand that you'd like to apply more torque for a shorter period of time - but that's just a matter of gearing. The only real questions are:

1. Is there some efficiency difference between storing energy in a spring versus a battery?
2. Is there some cost benefit in one mechanism versus the other?

My gut feel is that the spring doesn't discharge energy at all uniformly. Very high quality mechanical clocks go to a lot of trouble to even out the energy produced by the spring over time. All of that extra 'stuff' seems unnecessary if you use a battery to store the energy instead. Assuming the thing you're driving needs a uniform energy input, I think batteries will do a better job. NiCd and NiMH's have a fairly uniform voltage over most of the discharge cycle.

Cost is harder to estimate - but in our modern age, moving parts are generally avoided in favor of solid state stuff - so eliminating the spring seems like it would save money.

SteveBaker (talk) 01:42, 23 April 2014 (UTC)

Steve, I agree with most of what you say. I don't think this would be objectively better, or more efficient than batteries. Moving parts do wear down, etc. I thought maybe with some clever circuitry it wouldn't matter if the spring output was uneven. Shouldn't a system of RLC circuitry be able to buffer the mechanical input, so that the electrical output is more even? E.g. a moving average. Don't conventional battery chargers already do a bunch of "smart" controlling of the charging process to deliver current and voltage at different rates? To clarify, my interest is for things like camping, hiking, biking, etc. As for storage, I guess a large capacitor with high-resistance gearing might make the spring a worthless complexity. So maybe I should think about how to get bigger capacitors and higher gearing onto one of those cell phone chargers I linked above? SemanticMantis (talk) 02:45, 23 April 2014 (UTC)

This reminds me ... it's been a few years since we discussed energy budgets for automatic watches: has anyone found a reliable source that quantitatively discusses comparative energy-budgets for digital and mechanical watches? Nimur (talk) 04:55, 23 April 2014 (UTC)

Well, how about this: There is an extremely comprehensive source for Seiko watches HERE, From a quick look at that document, the analog quartz watches mostly used between 0.8 and 2.0 microAmps for the movement and 0.3 to 0.8 microAmps for the "circuit block"...although there are lots of outliers in some of their models. So we're talking between one and three microAmps for a typical quartz/Analog watch. This delivers a battery life between one and five years. Surprisingly, the digital watches seem to use a lot more power - around 1.0 to 10 microAmps for the "movement" (presumably that's watchmakerspeak for "display") and between 0.8 and 3.0 microAmps for the "circuit block" - so maybe 2x to 5x more power consumption than analog watches. But with a similar battery life quoted for each...so probably there are more/bigger batteries in the digital models. A watch battery holds around 250 milliamp-hours of charge - and at 1.2 volts, that's 200 milliWatt hours or 720 Joules of energy.

I'm not sure that helps to illuminate this question though! As I explained above, our OP's problem lies mostly with the gearing on the crank rather than the technology used to store the energy...and perhaps we can use this example to illustrate the problem:

I recently bought a rather nice antique grandfather clock. It has chimes that go off every 15 minutes, a second hand and a moon-phase dial - and it runs for about a week using the gravitational potential energy of three (roughly 1kg) weights lifted through about a meter. This is a better way to store and retrieve energy than a spring because the force exerted by the falling weights is exactly constant over the entire week...but obviously it's a lot less convenient for portable devices!

Anyway, I can wind the three weights up to the top of the clock using the hand crank provided in about 5 seconds per weight. It takes quite a bit of force to turn the crank - but it's a reasonably comfortable rate to crank at - and a longer crank arm would probably allow you to crank at this rate for a considerable amount of time. Now, we know that for gravitational energy, E=mgh, so when I'm winding it up, I'm providing about 30 Joules of energy over 15 seconds of work - so I'm providing about 2 Joules/second or 2 Watts while I'm cranking it. When fully wound, my clock stores about 30 Joules of gravitational potential energy - about 24 times less than that 720 Joule watch battery! Which means that this gigantic clock could hypothetically run for 24 weeks - close to 6 months - on a battery that will power a quartz watch for two years. So this gigantic mechanical monster from the 1800's is only 4 times less efficient than a beautifully engineered modern watch - and it ticks loudly enough to be heard in the next room, chimes every quarter hour loud enough that I can hear it from anywhere in the house and keeps a gigantic pendulum swinging backwards and forwards against all of the friction generated by 100 year old bearings and gears!

I find that rather impressive - (or to put it another way, those fancy watches are surprisingly inefficient devices!).

SteveBaker (talk) 14:11, 23 April 2014 (UTC)

I'm not so sure that a watch battery can power a grandfather clock for 24 weeks. Assuming your math is all correct, you're just comparing energy, and ignoring all the details of how a battery would transmit mechanical power, at what efficiency/loss, etc! Which was kind of the information I was looking for here, but the other way around. Still, interesting comparison, thanks. SemanticMantis (talk) 15:10, 23 April 2014 (UTC)

30 Joules is 7 calories - so the clock consumes one calorie per day and by winding it every week as a form of exercise, I'll lose a whole pound of body fat after about 10 years of clock-winding.  :-) SteveBaker (talk) 16:26, 23 April 2014 (UTC)

Fascinating work Steve! I'm feeling nitpicky today, though! You claimed an exact property: "the force exerted by the falling weights is exactly constant over the entire week..." but that assumes the little g gravitational constant is exactly the same. In fact it changes slightly with respect to the height of the weight above the Earth's surface. (Not to mention the gravitational attraction of objects other than Earth!) I'll readily admit that the effect is negligible, but because you use the phrase exactly, I had no choice but to nitpick! Nimur (talk) 21:43, 24 April 2014 (UTC)

You forgot to factor in proton decay in the weights ! :-) StuRat (talk) 05:08, 25 April 2014 (UTC)

...or more mundanely, the gradually increasing uncoiled length of the cables suspending the weights slightly increases the pull that they exert on the clock mechanism. That effect might even be measurable. So, OK, if you're being super-nit-picky, I shouldn't have said "exact" - but the sense of what I was trying to convey matters here. The amount of power produced by a coiled spring as it unwinds is hugely variable compared to the almost constant amount of power produced by a falling weight.

The analogy with a car engine is useful here. An internal combustion engine has wild variations in the efficiency with which it converts gasoline into useful work depending on the RPM that it's turning at. Hybrid vehicles get the good mileage that they (mostly) do because they can run the engine at its optimum RPM all the time and use it to charge a battery that can provide spurts of high power when needed.

A similar thing happens with human-powered machines. We can only turn a crank at some limited ranges of speed, torque and duration - and to drive something directly from that input shares the same problem as a car engine. So using the crank to charge a battery is a good way to optimize the energy usage. Springs can be used (like a battery) to store energy - but they lack the ability to release that energy in a uniformly controlled manner without resorting to more complexity with mechanisms like a fusee. The falling weights in a grandfather clock are an elegant way to release stored mechanical energy in an almost uniform way - but clearly that's inconvenient in general. We have a six foot tall cabinet in our hallway - effectively doing the job that a wristwatch can do almost as well.

Finding a compact, lightweight and cheap way to store and release mechanical energy is therefore a difficult problem. Skirting it by converting the mechanical crank turning into electicity to charge a battery is a reasonable way to handle the problem. Springs are probably the second most convenient way - although they do suffer from this lack of uniformity of energy output over time. A flywheel is another possibility - but they tend to be either very heavy or they have to spin at such high speeds that they are in perpetual danger of flying apart and doing enormous damage in the process. SteveBaker (talk) 13:59, 25 April 2014 (UTC)

April 23

Basteria in diabetes control

Can high blood glucose level be controlled or reduced by introducing some non pathogenic strain of bacteria that is biotechnologically modified to not reproduce that will absorb glucose and decompose it.Is this possible.I am not a doctor but this idea occured to me.Please highlight and discuss.Has there been any research in this line.Ichgab (talk) 07:00, 23 April 2014 (UTC)

What's "basteria" -- bastard bacteria?  ;-) Anyway, if you put bacteria (bastard or not, modified or not) into your bloodstream, you'll get some really nasty consequences. 24.5.122.13 (talk) 08:30, 23 April 2014 (UTC)

Sorry for the typing error but i mean that the bacteria if it is biotechnologically maodified with the presently available hitech processes or if that is developed in near future to avoid sepsis then cant it be good method to control blood glucose level.117.194.232.254 (talk) 11:22, 23 April 2014 (UTC)

Well, that doesn't sound any better than injecting insulin, to me, unless the bacteria could be programmed to only reduce blood sugar when it's over a certain level. I seem to recall that some animal, (was it the Komodo Dragon ?) has a form of insulin which does that, so genetically modifying bacteria or other organisms to create that would be a great thing for diabetics, as they would no longer have to worry about overdoses causing dangerous blood sugar drops. And, without that concern, they could take a lot more insulin, say with an insulin pump, and thus avoid blood sugar spikes, too. Another approach would be to modify the insulin pump, from the current stupid version that injects insulin at a constant rate, to a smart one that injects insulin as needed, by taking blood sugar readings continuously. Of course, such a device would have to work 100% of the time, as a malfunctioning one could easily kill the patient. StuRat (talk) 12:07, 23 April 2014 (UTC)

Thanks for your clarification.117.194.238.140 (talk) 13:04, 23 April 2014 (UTC)

You're welcome. I looked it up, and Exenatide is the generic name of meds created from lizards (they list the gila monster, but other lizards, like the Komodo dragon, also have it). I was off a bit on how it works, though. Rather than being an insulin itself, it's derived from lizard saliva, and stimulates production of the patient's own insulin, and the patient's pancreas then releases insulin based on blood sugar levels, unlike the current insulin pump. StuRat (talk) 13:37, 23 April 2014 (UTC)

The questioner asked about "introducing" the bacteria. Besides in the bloodstream, bacteria in the gut could break down sugar. An example of what that latter process might be like is when one eats a large amount of icecream or candy made with sweet-tasting sugars that are not metabolized by the human body, as found in various diabetic or diet foods. The bacteria can produce huge amounts of gas in the intestine when they digest the alternate sugar resulting in painful and thunderous flatulence. The injectable diabetes drug Byetta, (brand name of exenatide) made identical to Gila monster saliva, besides stimulating insulin release from the pancreas beta cells, has the additional effect of slowing the emptying of the stomach thereby reducing the sudden rise in blood sugar after a meal. Edison (talk) 20:27, 24 April 2014 (UTC)

Introduced bacteria can run afoul of immune reactions, evolve to misbehave, etc. It just seems easier to grow islet beta-cells and put them into the patient - there are a wide range of ways in which this has been studied, such as pancreas transplants, islet transplants, encapsulated beta cells, stem cells, growth factors, etc. It seems like you'd have to start on a longer road from further behind than the current researchers. Wnt (talk) 01:04, 25 April 2014 (UTC)

Can (non-human) animals get sick because of their poo throwing habit?

Which animals besides chimps do that? Then they eat with those hands? Really? Sagittarian Milky Way (talk) 09:45, 23 April 2014 (UTC)

Yes, any animal can become sick when exposed to feces which carry a disease. However, they are less likely to become sick from their own feces, as presumably they have already been exposed to anything in them. There could be exceptions, though, by reintroducing an organism which otherwise would have been cleared from their system. So, you could think of feces throwing as a form of biological warfare, where they attack the target with the organisms in their feces.

In fact, the potential for transmission of disease is the whole reason we have evolved an instinct to avoid feces. Not all animals have such an instinct, though, such as dogs, which seem to eat other animal's feces. Presumably there is some corresponding benefit to them which surpasses the risk, such as if they can extract some nutrition from them and avoid starvation. StuRat (talk) 13:01, 23 April 2014 (UTC)

. --Jayron32 13:48, 23 April 2014 (UTC)

That would be [12].--Shantavira|^{feed me} 15:12, 23 April 2014 (UTC)

I've had the experience of a Mandrill (Mandrillus sphinx) contracting Tetanus from faeces, but it happened only because the animal (a big male) had overgrown canine teeth that had damaged the opposing gums making an open wound inside his mouth. Never any problems with other primates though. (The Mandrill survived, but it took some pretty intensive nursing to bring that about!) 122.108.177.30 (talk) — Preceding undated comment added 03:27, 25 April 2014 (UTC)

Obligate Parasites

What's an obligate parasite, and what makes it different from other parasites? The article says it "cannot complete it's life cycle without exploiting a suitable host". I thought this was the case with all parasites. I'm confused. --Yashowardhani (talk) 11:03, 23 April 2014 (UTC)

See facultative parasite for examples. I updated parasite#Types to list the two types, with links to the articles. StuRat (talk) 12:44, 23 April 2014 (UTC)

Got it! Thanks a lot, Stu. --Yashowardhani (talk) 07:17, 24 April 2014 (UTC)

You're quite welcome. I'll mark this Q resolved. StuRat (talk) 04:47, 25 April 2014 (UTC)

Resolved

Help with plant identification

Resolved

Unknown shrub

This plant has mysteriously appeared in one of our garden beds, and we can't figure out what it is. This is in Harlingen, Texas -- the Rio Grande Valley, right at the southern tip of Texas. I haven't seen anything like it in local yards, gardens, or the countryside. In case the picture doesn't make it clear, it is a shrub currently about two feet high, with a straight central stem covered with small stiff hairs, and opposed leaves. Does anybody recognize it? Looie496 (talk) 14:19, 23 April 2014 (UTC)

looks like Ragweed maybe Ambrosia trifida --Digrpat (talk) 14:49, 23 April 2014 (UTC)

It looks a bit like sassafras to me. However, Harlingen, Texas is a bit out of range for that one. --Jayron32 15:00, 23 April 2014 (UTC)

Maybe a ficus (fig) of some sort. See [13]. --Jayron32 15:10, 23 April 2014 (UTC)

After looking at pictures on Google Images, I'm satisfied that Ragweed is the right answer -- and I've expeditiously obliterated the plant. Thanks everyone. Looie496 (talk) 15:19, 23 April 2014 (UTC)

(EC) Pretty sure not a sassafras or ficus. Ficus have sclerotinous (i.e. hard, waxy cuticle) leaves, OP doesn't. Sassafras is an understory shrub, not a sun lover. It also would have obvious bark at that point, not a hairy stem. Looie, why do you call it a shrub? Is there any sign of woodiness at the base? From context, it seems much more likely to be a ruderal species of some annual plant. Ragweed seems like a good guess, but there are a lot of different varieties. Suffice it to say, it's most likely a weed. SemanticMantis (talk) 15:23, 23 April 2014 (UTC)

I called it a shrub because my knowledge of plant terminology is near the moron level, basically. Looie496 (talk) 15:31, 23 April 2014 (UTC)

See Parthenocissus quinquefolia commonly called Virginia Creeper. hydnjo (talk) 17:24, 23 April 2014 (UTC)

Sorry, also no. Virginia creeper has no hair on stems, stems are distinctly woody, and it couldn't get grow 2' straight up without extenuating circumstances. SemanticMantis (talk) 19:24, 23 April 2014 (UTC)

• Definitely not a Sassafras. They develop single-lobed leaves as juveniles of the size pictured. When they reach flowering maturity they have mitten-shaped two-lobe leaves. As the reach maturity they also have three-lobed,but never four or five lobed leaves so far as I am aware. Certainly not when they are under 30 feet in height with six-inch trunk diameters. μηδείς (talk) 21:55, 23 April 2014 (UTC)

• Get rid of it or you may end up getting shot. [14]--Aspro (talk) 00:34, 24 April 2014 (UTC)

Wow, that's insane. Especially because it doesn't look very similar at all, not to mention all the botanical characteristics that are off. SemanticMantis (talk) 16:44, 24 April 2014 (UTC)

It's green, ain't it? —Tamfang (talk) 03:37, 25 April 2014 (UTC)

ethylhexyl palmitrate/ethylhexyl salicylate

Is Ethylhexyl palmitrate and ethylhexyl salicylate the same or akin to each other? I have recently been allergic to octyl salicylate and trying to figure out which cosmetics I can use and wanted to know the relationship of these two chemicals. thank you. 173.187.108.228 (talk) 16:23, 23 April 2014 (UTC)

These compounds are both esters, which are composed of two structural units joined together. Ethylhexyl palmitate (note spelling) vs the salicylate are based on two different acid parts, but with the same 2-ethylhexanol attached. DMacks (talk) 16:36, 23 April 2014 (UTC)

April 24

Material

Do you know any other material that lighter and strong as plywood ?195.94.247.195 (talk) 06:43, 24 April 2014 (UTC)

Oriented strand board? --Canley (talk) 07:02, 24 April 2014 (UTC)

Aluminum? Shadowjams (talk) 07:21, 24 April 2014 (UTC)

Spider web, among many others. Stainless steel has a better strength to weight ratio than aluminum. You will find a list of materials in the specific strength article.--Shantavira|^{feed me} 07:46, 24 April 2014 (UTC)

Titanium? Oda Mari (talk) 09:25, 24 April 2014 (UTC)

It should be pointed out that oriented strand board, while comparable to plywood in certain applications, is an insufficient substitute in others. While good for uses with distributed forces (like subflooring), OSB doesn't hold up well when the forces are concentrated. I remember an episode of This Old House where they went to a hurricane test center. They demonstrated the difference betweeen OSB and plywood for protection of windows by simulating a wind-borne 2x4 board hitting it. While the 2x4 bounced off the plywood, it punched right through the OSB - the laminated sheets do a better job of spreading the concentrated force, whereas the strands in the OSB just ripped apart. -- 162.238.240.55 (talk) 12:59, 24 April 2014 (UTC)

It would help it we knew what you wanted to use it for. A simple google for "plywood substitute light" has plenty of options but it really depends on what you want to use it for. 196.214.78.114 (talk) 09:18, 24 April 2014 (UTC)

Agreed. Based on the baseline material being plywood, I'm guessing they want something inexpensive and it doesn't matter if it's flammable, and perhaps it needs to be a thermal and electrical insulator. In that case, some form of plastic might qualify, and would also be more water resistant than plywood. StuRat (talk) 03:06, 25 April 2014 (UTC)

For reference, "strong" isn't really a well-defined term, unless you specify what type of strength you mean. E.g. spider silk is mentioned above, but it relatively low shear strength and compressive strength, especially compared to plywood. What it is good at is tensile strength. Our article Ultimate_tensile_strength has a table sortable by density and other factors. You might also be interested in toughness, or our general article Strength_of_materials. As others have pointed out, we might be able to recommend a specific material if you have a specific use in mind. SemanticMantis (talk) 16:40, 24 April 2014 (UTC)

Celebrex in UK

Can anyone give me a link to a credible article that tells me why Celebrex was banned in the UK please? I googled on "celebrex banned in uk" and got lots of online pharmacies - oh and the WP page! Thank you.--TammyMoet (talk) 10:11, 24 April 2014 (UTC)

Who says it was banned? This (undated) article from the Medicines and Healthcare Products Regulatory Agency says 600,000 people in the UK take it. The NHS website has information about it here. Cancer Research has a page on the drug here. All of that suggests its currently prescribed in the UK. -- Finlay McWalterᚠTalk 10:22, 24 April 2014 (UTC)

The document name for the MHRA thing suggests its from December 2004. -- Finlay McWalterᚠTalk 10:23, 24 April 2014 (UTC)

The only relatively recent thing I can find at the MHRA's website is this 2011 document which notes the withdrawal of use for the drug in Europe, for the treatment of "intestinal polyps in familial adenomatous polyposis" - for reasons of inefficacy. I can't find any notice about its other uses, and no evidence of a general ban. -- Finlay McWalterᚠTalk 10:29, 24 April 2014 (UTC)

That reiterates European Medicines Agencys instruction. I can't find anything on their site that describes any general ban or voluntary withdrawal. -- Finlay McWalterᚠTalk 12:03, 24 April 2014 (UTC)

I also looked at the National Institute for Health and Care Excellence website. They don't explicitly mention Celecoxib or Celebrex, but if you put either term in, they link to their clinical best practice notes for conditions where they say COX-2 NSAIDs are indicated. Again there's no evidence there that there's any kind of UK ban. -- Finlay McWalterᚠTalk 10:48, 24 April 2014 (UTC)

From what I can gather the "MHRA should strive to uphold the current European legislative ban on DTCA" See: http://www.mhra.gov.uk/SearchHelp/GoogleSearch/index.htm?q=celebrex%20ban. So it would seem it is not the product but the method of marketing/distributing it. 196.214.78.114 (talk) 10:50, 24 April 2014 (UTC)

Well that's all odd. I used to be on Celebrex but was taken off it and was told it was because it was being withdrawn in the UK. --TammyMoet (talk) 11:47, 24 April 2014 (UTC)

There were concerns at one point (this is mostly according to our article on it) that it would suffer from side effects similar to Vioxx. Those concerns appear to have subsided. Discovery and development of cyclooxygenase 2 inhibitors is an interesting review of all the COX-2 inhibitors, of which both Vioxx and Celebrex are. Shadowjams (talk) 03:59, 25 April 2014 (UTC)

First moment of area

How do you know which dimensions to include when calculating the first moment of area? For example if you're calculating the shear stress at a particular point on a rectangular beam, you would calculate the 2nd moment of area for the whole beam but for the first moment of area, which dimensions do you use for the area? I'm trying to calculate the first moment of area in question 1 of this example, http://www.docstoc.com/docs/78966553/ENGI3110PP2. I also don't know which value to use for the thickness. Clover345 (talk) 20:34, 24 April 2014 (UTC)

April 25

Nonhuman vocal flexibility (or, what does the fox NOT say?)

According to these sources, foxes produce an extraordinarily wide variety of calls, and can imitate the calls of a wide variety of prey species. Maybe it's no coincidence that humans also have this ability, and that humans and foxes are among the least-endangered species of apex predator? Have studies tested whether the diversity of sounds a species can articulate is correlated with its position on the food chain or its modern conservation status? NeonMerlin 03:50, 25 April 2014 (UTC)

There are counter examples of great vocalists who are extinct as well. Shadowjams (talk) 04:05, 25 April 2014 (UTC)

Mimicry can be an important survival skill, but sound mimicry is only one type, and there are many other survival skills besides mimicry. StuRat (talk) 12:52, 25 April 2014 (UTC)

When you consider the survival of foxes in an increasingly hostile world, there are many aspects to their lifestyle that make them well suited - for example, they are omnivores - this allows them to easily switch food sources be highly adaptable to environmental changes. They also have a reputation for high intelligence. Mostly though, their ability to survive in places where humans dominate means that they are less inclined to suffer when we encroach on their territory. So why would you imagine that (of all things) vocal range has anything to do with it? There are many more things that are by far more likely to be the dominant reason for their continued success. SteveBaker (talk) 13:33, 25 April 2014 (UTC)

Agreed, vocalization is not likely to be a big factor. Usually, Animal_communication#Auditory is more inflected and complex in social species, e.g. cetaceans, birds, simians, canids, etc. I just searched google scholar for any article that seemed to mention complexity of vocalization and trophic status, to no avail...

By far, most endangered species have that status because of humans mucking up the animals native habitats. Foxes, racoons, sparrows, rats, groundhogs, deer... these are all simply animals that deal well with habitat fragmentation and habitat destruction by humans. Sometimes called human commensal species, they have readily adapted to the environments that humans have created. Things like rats and sparrows reach far higher populations in human cities than in their historical wild ranges. Interestingly, both foxes and beavers were recently much scarcer, but are on the rebound throughout much of the USA, indicating to me (WP:OR) that it took a little time for them to sort out how to live in our world. SemanticMantis (talk) 15:25, 25 April 2014 (UTC)

Agreed. Foxes are renowned for their intelligence, as in Aesop's fables. I saw one fox actually using cars to feed itself. It waited off the shoulder of a road for a car to drive by, which seemed to scare rodents in the brush, who then moved, and the fox pounced on them when he spotted the weeds moving. Also, I've never seen a fox dead on the road, so they apparently are smart enough and fast enough to avoid that fate, while cats seemingly are not. StuRat (talk) 16:02, 25 April 2014 (UTC)

The question of rules and mains of conductoring inserting

Why on the page about electric conductor is not been contain about the all ways of including a conductors in a electric which always been setting up the all electrical rules? I seen, that a parallel or a simple insertings of all conductors in a electric is been most interested than a material structure of all conductors. More thanks!--Alex Sazonov (talk) 10:36, 25 April 2014 (UTC)

Are you asking about a series and parallel circuits ? Our electrical conductor article is about a conductor itself, not how it behaves in an electrical circuit. StuRat (talk) 12:46, 25 April 2014 (UTC)

Yes, I’m about of a series and a parallel including in a electric. But it seems that all conductors always none before had been belong a way of a electrical including, because all conductors always been created by a ways of a electrical including, thats it seems that it must been in page about a electrical conductors. Thanks!--Alex Sazonov (talk) 14:36, 25 April 2014 (UTC)

You're welcome. In English, at least, an "electrical conductor" has a wider meaning than just a device in an electric circuit. For example, saltwater is an electrical conductor. So, we have a separate article about electrical circuits. StuRat (talk) 14:51, 25 April 2014 (UTC)

Thanks more at all, it been all conductors always are beening as ways of a electrical including, but of course you right in English it had been meaning as a material or as a structure of material which had a electro-statically magnetism as it been done.--Alex Sazonov (talk) 15:13, 25 April 2014 (UTC)

As had been know as well, a ways of a electrical including of all conductors may been doing a super electrical resonance, that’s why a way of a electrical including of a conductors will be done a superconductivity as I know well the science it. Thanks.--Alex Sazonov (talk) 17:07, 25 April 2014 (UTC)

We have an article on superconductivity, too. StuRat (talk) 18:00, 25 April 2014 (UTC)

Very thanks, it seems me that must be explain in page about a superconductivity thats, the fact of a superconductivity always is been a science electro-technical effect in a applied physics which effect, always has been a simple science base of all electronics and all microelectronics as why that a superconductivity was been scientifically discovered at first in a electro-technical engineering, and someone alls could be explain that a superconductivity always is been effect of colder of all metals, but someone science always wanted a science as a superconductivity always had been a science of very colder melting of all metals. It always seems me that a superconductivity always been good as electro-technical effect in a applied physics but not it been as a colder effect, lets I always think it is been always science.--Alex Sazonov (talk) 18:26, 25 April 2014 (UTC)

Spider that looks (and kind of acts like) a fire ant?

Sitting on the porch I encountered what I thought was a fire ant - it looked exactly like one but with unusually large mandibles, and it's movements were certainly characteristic of one too. But when I went to relocate it, to my surprise it dropped down on a silky thread! So just out of curiosity, I decided to place it in a large fire ant hill on the edge of the property. In fact, it just meandered about on the hill for a while without so much as raising suspicion from the normally-aggressive residents. Any ideas what kind of spider it was? I didn't have a chance to get a photo, unfortunately. 70.117.71.28 (talk) 15:59, 25 April 2014 (UTC)

Things That Are Not Fire Ants may help :) --— Rhododendrites ^talk |  16:03, 25 April 2014 (UTC)

Cool find! I could be mistaken, but I didn't see any spiders on Rhodo's link. Ant_mimicry#Spiders discusses that ant mimicry by spiders is very common, but is not very helpful for our purposes here. Also, many things other than spiders can make silk, and some of them are ants. E.g. weaver ants use silk to make nests. So, unless you clearly counted eight legs, and are sure there was no pedicel, you may have just found some other, silk-making ant.

With a little further searching, though mistaking this salticid for a fire ant seems totally reasonable [15], and they do often perform a classic rappelling escape maneuver, just as you describe. That youtube video suggests it might be a member of the genus Peckhamia, more pics on Bug Guide here [16]. Also, salticids have a habit of waving their mandibles about, and that might also fit with your description. SemanticMantis (talk) 16:23, 25 April 2014 (UTC)

Slow neutrons

Why are slow neutrons better at inducing nuclear fission than fast neutrons? 65.92.5.76 (talk) 17:49, 25 April 2014 (UTC)

Per our neutron temperature article, which is the first search result Google returns for "slow neutron":

Thermal [i.e. "slow"] neutrons have a different and often much larger effective neutron absorption cross-section for a given nuclide than fast neutrons, and can therefore often be absorbed more easily by an atomic nucleus.

It happens that that cross-section is more relevant for readily-fissile materials; note elsewhere in the article, though, that fast neutrons serve their own purposes in fission-based applications (such as breeder reactors). — Lomn 18:00, 25 April 2014 (UTC)

Bird with a red patch on the back of it's head ?

I saw this small bird in Detroit. It occurred to me that it could be a female cardinal, as females often have less color, but the pics I found didn't much look like it. Same for a female American robin, and they tend to be more orange than red, in any case. I did get a cell phone pic, but it's of such low resolution it may not be of much use here. StuRat (talk) 17:58, 25 April 2014 (UTC)

What color was the rest of the bird? Could it have been a Red-winged Blackbird? The red patch is on the wing, but maybe from an angle it could look like it was on behind the head. - Eron^Talk 18:05, 25 April 2014 (UTC)

Color-changing eyes

My sister's eyes change color. From birth until about 3 months old they changed between gray, green, blue and gold, like the girl's contact lenses here: http://4.bp.blogspot.com/-ctwEOwlzmYc/UGnUCTNnciI/AAAAAAAAAD4/WKZwNT_Ibe8/s1600/girl2.jpg By 4 months old she had hazel eyes and they stayed hazel until she was 12 years old. When she was 12 they turned light green for about one whole day and she didn't even notice until her friends started asking her about her contact lenses. But she wasn't wearing contacts! The next day her eyes were still green but you could see the hazel coming back. When she turned 14 her eyes started turning almost black during the winter and in the summer they turn light brown, not hazel but light brown. Now its spring and she has one light brown eye and one dark brown eye. This might sound crazy but its true. Her eye color changes were noticed not only by her but by her friends and family, sometimes even before she had noticed it herself! So what does this mean? She also wants to know if they'll ever change back to blue or green. — Preceding unsigned comment added by 68.8.106.52 (talk) 18:34, 25 April 2014 (UTC)

These links might be helpful.

• http://www.allaboutvision.com/askdoc/
• http://www.geteyesmart.org/eyesmart/ask/index.cfm

—Wavelength (talk) 18:50, 25 April 2014 (UTC)

An explanation is at http://www.allaboutvision.com/conditions/eye-color.htm.

—Wavelength (talk) 18:54, 25 April 2014 (UTC)

How does nuclear fusion generate energy?

It seems to me that a nuclear fusion reaction like deuterium + tritium --> helium + neutron should result in an energy loss rather than an energy gain. The nuclear binding energy in a nucleus should be approximately proportional to the number of pairs of nucleons. Well, deuterium has one pair of nucleons, tritium has three pairs, while helium has six. So it seems that there should be an increase in nuclear binding energy, rather than a decrease. 65.92.5.76 (talk) 19:11, 25 April 2014 (UTC)