Wikipedia:Reference desk/Archives/Science/2013 November 3

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November 3

Nuclear radation concerns for Utah salt lakes

Someone said a university in Utah is studying radiation of sea salt from Utah salt lakes. I use a brand of sea salt in my cooking and wonder if there is a connection. Of course checked the manufactures web site and nothing but glowing reports there. company selling the sea salt is based in Heber, Utah, near salt lake. 99.108.30.42 (talk) 02:30, 3 November 2013 (UTC) Fred W — Preceding unsigned comment added by 99.108.30.42 (talk) 02:16, 3 November 2013 (UTC)

Sea salt is naturally slightly radioactive due to potassium salts it contains, but nowhere near enough to matter. 24.23.196.85 (talk) 06:12, 3 November 2013 (UTC)

I am concerned about underground nuclear tests in past which vented radioactive gases in that area and may have contaminated the sea salts. Sorry, I did not really think through my question. 108.78.185.140 (talk) 15:27, 3 November 2013 (UTC)

There are many potential reasons, because isotope analysis is a general geology technique and Utah is a site of commercial potassium extraction and other mining. Gamma ray logging apparently takes advantage of potassium's natural radioactivity, while potassium-argon dating is useful for dating deposits. From what you've said, this could be related to anything from fertilizer production to oil prospecting. Wnt (talk) 15:38, 3 November 2013 (UTC)

Also, regarding nuclear testing: (1) None of the tests were in the immediate vicinity of the Great Salt Lake; (2) All but a few nuclear tests in the Continental USA were done at the Nevada Test Site, which is pretty far away from the Great Salt Lake -- so the amount of fallout reaching the lake was small; (3) Atmospheric nuclear testing in the USA was discontinued after 1962 -- so almost all of the radiation that did reach the Great Salt Lake should have decayed by now; and (4) As for underground nuclear tests, the amount of radiation that reaches the surface is medically insignificant. 24.23.196.85 (talk) 06:35, 4 November 2013 (UTC)

Reversing batteries in compartment saves the batteries from trickle charge depletion, why?

I have reversed my batteries in old flashlights, walkmans, portable electric razors, etc. and the batteries stay fairly fresh and usuable when needed and reversed, even after six months or more. Why is that and is there any potential for using that approach in conserving energy on big scale, such as a electric power plant.

99.108.30.42 (talk) 02:26, 3 November 2013 (UTC)

You took the batteries out and put them back in with the + and - ends reversed? Wow! Well:

• For a simple incandescent bulb flashlight - this can't possibly make a difference. The only active component in the circuit is the bulb itself and it is basically just a resistor - it has the same resistance no matter whether it's driven forwards or backwards. Since V=IR (ohms law) - the current that flows depends on the resistance - I don't see how reversing the battery could possibly have any effect whatever. For a modern LED flashlight, it won't work - and you might destroy it.
• For things like a Walkman - which has electronic circuits in it - you're running the risk of destroying the electronics by doing this - so I strongly advise you not to do it anymore! You're probably getting away with it because the battery is alreay depleted...but it's a really bad idea! It's also unlikely that these devices would work with the batteries reversed...so I can't believe you've actually done this.
• For electric razors...simple, old-style razors are basically just DC motors. The motor would probably run backwards - which might mean it still shaves OK - but maybe not. More modern razors may have some basic electronics in them - and just like with a Walkman, you'll probably damage it.
• Worse thing, the little spring that is supposed to press against the negative end of the battery can possibly short out the positive end - it's not likely - but if you do short out the battery you'll cause rapid overheating and possibly even a fire, even if the battery is towards the end of it's life.

Sorry - but this sounds like complete nonsense. Certainly we're not going to save energy by doing this - and most likely, this advice will cause people to destroy expensive electronics by attempting it.

SteveBaker (talk) 02:50, 3 November 2013 (UTC)

Could there possibly be electronic circuit protections against reversed polarity which create an open circuit and thus prevent discharge ? StuRat (talk) 04:06, 3 November 2013 (UTC)

Diodes have asymmetric conductance, only allowing current to flow in one direction, so when reversed polarity current reaches a diode, it essentially creates an open circuit. This is why, as Steve mentions, LED (Light Emitting Diode) flashlights won't work with the current reversed. But everything Steve says above is correct. It isn't a good idea and may ruin more delicate circuitry. In fact, I believe the fine print on battery packages warn against it (at least in the U.S.) saying things like "fire or other injury may result".--William Thweatt ^TalkContribs 05:33, 3 November 2013 (UTC)

Yep, nobody is saying it's a good idea, but conceivable an LED flashlight, which slowly drains batteries placed in normal polarity, might not drain them in reverse polarity. StuRat (talk) 06:08, 3 November 2013 (UTC)

First time here on this and entry about salt in Utah, entered just before it. So I do not think I adequately explained myself. My uncle used to do this years ago to save on batteries. Here is what I have been doing.... I reverse the batteries when the device is not in use, then reverse the batteries for correct polarity when use is intended. I have used this on three LED flashlights and no problem. Neither a problem on walkman, razors. In fact many manufactures used to ship with batteries reversed. Now I am not saying that some circuits would not be harmed with the reversing, only that those I described were not and batteries held up much much much longer (six months to a year) than if simply left grow weak while device in "off" position.

I was wondering whether the explanation might be that reversing acts like a kind of capacitor, forestalling any discharge and weakening? 108.78.185.140 (talk) 15:12, 3 November 2013 (UTC)

I'd suggest that the explanation may be rather mundane: the normal cells (AA, AAA, D, C) have the + contact protruding, and the − contact flat. Battery compartments often have a recess around their contact for the cell's + contact. Reversing the cells would then break the circuit entirely, due to the geometry. This will not be the case for all battery compartments though. So check for this.

A further caution: a cell that is disconnected will self-discharge over months or years, and many cells (even sealed cells) when discharged have a tendency to leak electrolyte, which is generally highly corrosive. So storing cells in this manner is not generally advised if consequent damage must be avoided, but as a short-term storage alternative to simply switching the device off, reversing all cells (or simply the last cell) would be effective, provided that the shape of the compartment has a suitable geometry. 24.165.90.120 (talk) 17:15, 3 November 2013 (UTC)

The solution to the problem of potentially leaking acid from batteries is to store them in such a way that the electronics are above the batteries. You could also remove the batteries and store them elsewhere, but that's not so good, say, for a flashlight you might need to have immediately functional in a power failure. StuRat (talk) 17:24, 3 November 2013 (UTC)

When the user says that reversed batteries stay fresh and usable for 6 months, I say "So what?" A turned off device typically has an open circuit at the switch and no current trickling through some circuit. An alkaline battery today has a 5 year shelf life if not used (some more expensive battery types have a 10 year shelf life). So unused batteries in normal or reversed polarity in a device with an actual on-off SPST switch, at normal room temperature, should all be fresh enough for use after 10 times the stated 6 months. Storage life for a partially discharged battery is not so clear, but I still doubt a benefit from it being in a device with polarity backwards and the switch off. If current is not flowing, how does the polarity matter? Some more sophisticated gadgets powered by batteries might require some slight current to keep a clock powered, but such functions are so low current draw that a small button cell can typically keep them going for years. But if they draw some idle current and if they have a diode for reverse polarity protection, then the reversing trick might keep the batteries fresher, but at the cost of losing the clock time or the stored settings or whatever. Edison (talk) 22:36, 3 November 2013 (UTC)

But some devices which shouldn't need electricity, when not in use, nonetheless seem to slowly drain the battery when turned off. Conceivably, putting the batteries in backwards might stop that. Of course, removing them entirely should do the trick too, but that's not quite as handy. StuRat (talk) 00:19, 4 November 2013 (UTC)

Standby power is our article about that.

So, it seems that there are several possible directions here:

1. Some devices will be permanently damaged by doing this (especially electronics). CONCLUSION: don't do it.
2. Some devices may short out a reversed battery causing rapid overheating and possible fire. CONCLUSION: don't do it.
3. Some devices may detect reversed batteries and protect themselves from damage, this action may well drain the battery. CONCLUSION: don't do it.
4. Some devices (eg incandescent flashlights) won't be affected by it...they'll function and drain the battery just the same as if the batteries were not reversed. CONCLUSION: don't do it.
5. Some devices may fail to make contact with a reversed battery...so reversing them does the same thing as removing them. Aside from the battery compartment being a convenient place to store batteries - there is no gain to doing this. CONCLUSION: Well, no harm, but not much gain either.
6. Some devices consume no power whatever when turned off - so either reversing or removing the battery has no effect. However, removing them avoids the problem that old batteries leak and reversing them does not. CONCLUSION: Remove the batteries, don't reverse them.
7. Some devices might consume power even when turned off (so-called "Standby Power") - and removing the batteries will definitely save energy - but at some loss of functionality due to loss of whatever function that standby power provided (eg keeping a clock running on time or providing a faster turn-on time). Reversing the battery will save just as much energy as reversing them - but all of the above caveats apply. CONCLUSION: Remove the batteries

My conclusion is that there is rarely a saving from removing the batteries from the device - and never a saving from reversing them instead. The only possible reason to reverse them is because the battery compartment is a convenient place to store the batteries. But this is a terrible habit to get into doing because of the high risk of damaging the equipment or overheating the batteries and causing an even bigger disaster. Because there is no possible gain and a ton of risk, it's a bloody stupid thing to do. There is no magical way that the life of a reversed battery can possibly be more than that of a removed battery...it's just impossible.

Personally - I think that habitually reversing batteries without knowing a hell of a lot about the device you're doing it to is an incredibly bad idea...it's not going to help and one day you're going to destroy something expensive by doing it!! If you absolutely *MUST* store batteries inside a device that slowly discharges them due to "Standby Power" - then insert a small slip of paper between the battery's positive terminal and the battery connector. In most devices, you only need to do this to one of the batteries to disconnect all of them. This will disconnect the battery and ensure that you get the most life possible.

My advice is to remove the batteries completely only if there is reason to think that standby power is a problem. That guarantees that the battery life is maximised and that battery leakage won't ruin the device. But never, ever, reverse them - that's just dumb.

SteveBaker (talk) 00:58, 4 November 2013 (UTC)

Reversing one battery (assuming even number of two batteries) might extend the life. This would present a 0 volt source across the device. --DHeyward (talk) 15:42, 4 November 2013 (UTC)

It would have NO practical effect. This is because with the device switched off, no current can flow. If no current can flow, you get the cell's normal shelf life anyway. For modern cells, shelf life is typically 10 years or more. I have just purchased some Duracell AA's. The pack has prominently displayed "Guranteed for 10 years in storage." In any case, the current drawn does not have to be zero. Every cell size has a shelf life current - the current at which the shelf life is still obtained. In general, in electronic devices that draw a standby current, the standby current is below the shelf life current.

It is possible that the OP has repeated an old wive's tale - many of which had some basis in fact many many years ago. Up until the 1950's dry cells were made with carbon-zinc technology using ordinary cardboard cases around the zinc tube. They had a heck of a lot less energy capacity than do modern cells. Cardboard absorbs water from air humidity. Thus a series chain of such cells could have significant leakage current through the cardboard cases, especially if the cardboard was in contact with a metal torch case or battery holder (no plastic battery holders or cases back then). Once leakage current gets above a certain level, it then causes electrochemical effects that further increase the leakage. Reversing every second cell would minimise the voltage driving the leakage current. Therefore, these long obsolete cell types MIGHT have lasted slightly longer if you did store them with every second cell reversed when humidity was high.

It's a bit like flooring the accelerator in a car just as you turn the ignition off. In the early days, 1900 to 1910 or thereabouts, when engines were crank started and had very low compression ratios, it did make engines easier to start, as one cylinder was left in the compression stroke with a charge of fuel+air in it. The low compression meant that the piston rings could hold the charge for hours, so as soon as it was cranked to top dead centre it could fire. There has been no point in doing it for ~100 years, but you still sometimes come across some idiot old geezer doing it in his Toyota.

124.182.12.166 (talk) 01:55, 5 November 2013 (UTC)

That would be correct for mechanical switches, not electronic ones. Any device that has over/under/reverse polarity detection or electronic detection switches will leak off energy through semiconductor junctions. Your 10 year shelf life batteries will not last 6 months in a Wii controller that is off all the time. --DHeyward (talk) 06:34, 5 November 2013 (UTC)

You have no idea what you are talking about. Devices with under/reverse polarity protection can, and normally will, still have a mechanical on/off switch. Reverse polarity protection can be a series diode - negligible reverse current (nanoamps) there. In devices that run off only 1 or 2 cells, a series diode drops too much voltage, so a power mosfet is used to shunt the diode, bias for the osfet being available when the device is running. The current when off is still negligible. In a dry battery device, over voltage protection is not required, as it is difficult to put too many series cells in. It may however be a good idea in devices running off rechargeable batteries. In older devices, reverse polariy protection may involve shunt paths, but that means putting the cells in backwards is a bad idea, as has been already covered. With the cells in correctly, the shunt paths do not apply. You are pretty much wrong in saying any device electronic detection switching will/must leak off energy through semiconductor junctions, as mosfets need bias voltage to draw current. With modern CMOS circuitry (and CMOS goes back to the 1970's), it is easy to design so that standby current is below the battery shelf life current. So, these days, no benefit in sticking cells in backwards, not for all of them, not for half of them. Only a possible benefit when cells where still carbon-zince chemistry in leaky cardboard tubes. 120.145.77.78 (talk) 08:53, 5 November 2013 (UTC)\

Creating a 0V source by reversing 1 of 2 AA batteries in electronic device WILL extend life. Try it with a Wii controller. CMOS subthreshold slopes and leakage are well known. All modern CMOS devices have ESD protection which is a leakage path, as well as diode leakage, subthreshold leakage, RTC power use, etc, etc. Turn your cell phone off with the electronic switch and see how long it lasts. It might be weeks, but not years. Not even close. Depending on the PMIC, variability even between devices can be huge. "Off" leakage currents are very real in CMOS and even more so as the technology gets smaller and leakage increases with smaller Vt. --DHeyward (talk) 06:26, 7 November 2013 (UTC)

DHeywood, you definitely have no idea what you are talking about. Looks like you've read a few things and not understood at all the context. You cannot reverse some or even all cells in a cellphone battery - they are physically made so that you can't. So, totally non relevant to cellphones. CMOS devices do indeed have ESD protection on each input pin - it consists essentailly of a series resistance, which being in series cannot contribute to leakage current, and shunt diodes. The diodes do add to the leakage currents drawn from the supply rail, but, as the diodes will be reverse biased, it is of the order of adding (at ordinary temperatures) nanoamps to nanoamps for each input so protected. I've checked databooks I have, and the Quiescent Device Current, to use the correct term for standby current drawn from the supply rail is given for 25 C, variously in the range 0.5 to 5 microamps for a wide range of CMOS chips of differing complexity and pin count. This is all quite below the shelf life current for common Duracell, Eveready, etc, cells. 121.221.53.176 (talk) 13:12, 7 November 2013 (UTC)

Ion/Isub is a standard metric provided for performance comparison of CMOS processes. Vt determines the ratio. You're missing the big picture if you only think diodes contribute to leakage power waste. Leakage vs. drive strength is the main driving difference in cmos process offerings today. Once you apply voltage to the transistors (i.e. apply power to the n-well by having batteries installed), all those inverters will have Isub leakage (as well as gate leakage and diode leakage). It is one of the fundamental design considerations for microprocessors today. It is the reason for PMICs and it's the reason for for multiple voltage domains within a single SOC. --DHeyward (talk) 14:32, 7 November 2013 (UTC)

While the whole chip draws only 5 microamps or less, all your squawk doesn't matter. And most chips draw a lot less than that when not actively switching or processing. You are like a hospital cleaner trying to tell the brain surgeon about brain surgury. There is no point in putting half the cells in backwards, even when it is physically possible, as has been explained, and that is that. 1.122.242.46 (talk) 14:55, 7 November 2013 (UTC)

All devices that don't have mechanical switches (either a mechanical bi-stable switch, or an electromagnetic relay that triggered by a push button) will have a solid state relay. These have leakage currents, usually below 1 mA. Electronic equipment may have an internal clock that is powered even when the device is turned off. Memory keeping system settings often needs power as well. An electronic camera or mobile phone for example. Whether reversing the batteries is a good idea, I don't know, I would rather go for SteveBaker's suggestion, put something insulating between the contacts (I would go for plastic rather than paper because paper can conduct electricity somewhat, at least that's my experience with self-made capacitors)... Ssscienccce (talk) 17:14, 5 November 2013 (UTC)

The internal clocks used in battery powered devices draw about the same current as watches - they use that same sort of CMOS clock circuit. This current, which will typically flatten a watch button battery in about 3 to 5 years, is negligle for devices like cameras and phones that emply much larger batteries. Memory is provided by CMOS memory, which requires voltage but draws practically no current (nanoamps) when not being addressed. In the case of mobile phones and cameras, well, in all the devices I've seen, the battery, always rechargeable, is shaped in such a way that it is physically impossible to install it the wrong way round. 1.122.189.248 (talk) 01:06, 6 November 2013 (UTC)

Great Flood of 1993

I remember the Great Flood of 1993: I was a child in Ohio at the time, but every night the TV news was full of images of broken levees, flooded towns and farmland, and people stacking sandbags in tons of Upper Mississippi localities. What I don't remember was any discussion of flooding on the Lower Mississippi, and this article says the lower Mississippi basin was spared major flooding because the Ohio Valley, the Southern Plains, and basins in the southeastern U.S. did not experience the intense runoff that occurred in the Missouri River and the upper Mississippi River drainage. Why? I understand that the lower part of the river didn't get the heavy rain that occurred farther north, but the water has to go somewhere; why didn't the heavy rains from upstream cause also flooding when they flowed far downstream? Nyttend (talk) 04:16, 3 November 2013 (UTC)

As I recall from the time, the lower Mississippi (which is really the lower Missouri, but they don't call it that) is much broader and was able to absorb the excess runoff from upstream. ←Baseball Bugs ^{What's up, Doc?} carrots→ 04:29, 3 November 2013 (UTC)

I distinctly remember that flood, and while where I was living at the time wasn't decimated, I remember how bad it was. I would echo Bug's memory: the upstream rivers flooded badly but that didn't necessarily translate into downstream floods of the same proportion. Shadowjams (talk) 04:41, 3 November 2013 (UTC)

There's a whole branch of science dedicated to addressing questions like this, namely Hydrology. From what I can remember from my Civil Engineering days long ago, it involves taking into consideration things like flowrate, absorption rates of the different types of earth that make up the riverbed in various regions, etc. I don't know about the 1993 flood, but usually what prevents flooding further downstream is the preparedness of reservoirs downstream from the immediate flood area and their ability to take in the increased volume and release it fast enough yet without causing additional flooding. To oversimplify it a bit, reservoirs further down the Mississippi, where they didn't get the heavy rains, were aware that the flood waters would be coming and probably opened up their dams as much as they could to allow room for the incoming water. With each successive reservoir/dam system, the problem became less and less severe. Some other terms you might find interesting or may lead you to more links: Hydrograph, Hydrogeology, Behavioral modeling in hydrology.--William Thweatt ^TalkContribs 05:02, 3 November 2013 (UTC)

Something else to add is that successful flood control upstream often leads to flooding downstream. That is, if they were able to contain the water in the river upstream, it would then pass downstream in short order, and cause problems there. However, since they weren't able to contain the water upstream, and it flooded out over a wide area, this water did not immediately go downstream, and had time to soak into the ground, evaporate, etc. StuRat (talk) 05:09, 3 November 2013 (UTC)

The main source of water in the Lower Mississippi River is not the Upper Mississippi. It's the Ohio River. See, for example, Project design flood: the worst-case scenario for flooding the Lower Mississippi calls for almost ten times as much water coming in from the Ohio than from the Upper Mississippi and Missouri Rivers combined. --Carnildo (talk) 03:03, 6 November 2013 (UTC)

Male Body Purposely Permanently Completely (As In 100.00%) Stops Producing Sperm

Is there any way that the body of a male will purposely permanently completely (as in 100.00%) stop producing sperm other than with hormone replacement therapy/a sex change? I am genuinely extremely curious about this, and Yes, this is an extremely serious question. Thank you very much. Futurist110 (talk) 05:41, 3 November 2013 (UTC)

Our azoospermia article may give you some leads. --Trovatore (talk) 06:01, 3 November 2013 (UTC)

Thanks, though azoospermia is not something which any fertile male can voluntarily get, is it (this is sort of what I was asking about in my OP here)? Futurist110 (talk) 06:11, 3 November 2013 (UTC)

Oh, I see. It wasn't clear from your question that you were talking about this happening on purpose. Then, you might want to see male contraceptive#Pharmaceutical methods. --Trovatore (talk) 06:18, 3 November 2013 (UTC)

Yeah, I apologize--I should have made my OP clearer earlier. Anyway, thank you very much for your link. I will make sure to check it out. I wonder if any of these contraceptives will purposely do this (what I am asking about in the OP) permanently (and/or for however long a male desires to do this). Futurist110 (talk) 06:41, 3 November 2013 (UTC)

Castration ought to get the job done. And a vasectomy doesn't stop it from being produced, but does stop it from being delivered. StuRat (talk) 06:05, 3 November 2013 (UTC)

Thanks. I already knew about castration but I forgot about it for the time being. As for a vasectomy, thank you, but I was asking specifically about the stopping of sperm production here (plus, I already knew what a vasectomy does). Futurist110 (talk) 06:11, 3 November 2013 (UTC)

I think a low protein diet might also have this effect, as part of the man's starvation response. StuRat (talk) 06:14, 3 November 2013 (UTC)

Now that is interesting, if it is true. I'll need to research this a bit more. Futurist110 (talk) 06:17, 3 November 2013 (UTC)

I should add that such a low protein diet would have many other undesired and dangerous effects, so obviously not something to be tried. StuRat (talk) 06:25, 3 November 2013 (UTC)

Thank you very much for this warning. Futurist110 (talk) 06:41, 3 November 2013 (UTC)

For the record, in my OP here, I meant the purposeful permanent complete (as in 100.00%) stopping/halting of sperm production in male bodies using/in a way that any/every male can do this if he wanted to. Perhaps I should have been clearer about this before. Futurist110 (talk) 06:17, 3 November 2013 (UTC)

There might only be clues (see Spermatogenesis#Influencing factors), not definite answers or known solutions. All a matter of knowledge of how things work, and hacking (or rather engineering) accordingly. -- Lindberg 13:26, 3 November 2013 (UTC) — Preceding unsigned comment added by Lindberg G Williams Jr (talk • contribs)

Rubbing contact lenses

Please help me settle an argument. Many organizations, including the CDC, now suggest rubbing contact lenses with the disinfection solution prior to storage. I'm arguing with someone who thinks rubbing with saline is enough. I say that it's like washing your hands with water versus using soap. Who is right, with references if you can? Thanks. 67.243.4.94 (talk) 13:12, 3 November 2013 (UTC)

The answer to your question is given here. Richerman (talk) 14:04, 3 November 2013 (UTC)

This sounds like a medical advice question to me. I think it would be appropriate for us to give sources we can find for either side of the argument, but we can't tell you who's right, which depends on a wide array of real world factors. For some people, who develop contact lens associated problems, perhaps neither was right. Wnt (talk) 15:27, 3 November 2013 (UTC)

It does to me too. That's why I didn't give a direct answer:) I expect the American academy of Ophthalmology know what they're talking about though. Of course, they always give the caveat "Follow the specific contact lens cleaning and storage guidelines from your eye care professional and the solution manufacturer". Richerman (talk) 15:43, 3 November 2013 (UTC)

The advice in the link that Richerman provided generally seems good, but they left out one important fact: when washing your hands, don't use an anti-bacterial soap, because the alcohol residue in it can transfer to, and damage, the contact lenses. Instead, use something like Ivory, which does not contain alcohol. (That was the advice a few years ago, anyway.) And Wnt is right, this is ultimately a medical advice question. If you're wearing contacts, follow your eye doctor's instructions - and if anything in that link contradicts what your eye doctor said, call and ask about it. Your eyes are important, and you only get two of them, so don't screw around with them. ←Baseball Bugs ^{What's up, Doc?} carrots→ 15:46, 3 November 2013 (UTC)

I rub my contacts with solutions as called for by manufacturers and CDC. The other person rubs them with saline before disinfecting with solutions. He doesn't, for some reason, follow their advice, but will listen to anyone or webpage, like the Cleveland Clinic, who says rubbing contacts with saline prior to disinfection is fine. 67.243.4.94 (talk) 23:45, 3 November 2013 (UTC)

Mites or similar

I need some assistance to identify some unpleasant invaders who seem to be immune to everything designed to kill creepy crawlies, short of fire. I went to use my computer at home about 2 nights ago, and found the keyboard absolutely heaving with these very small white things which look like mites - they are about the size of the non-sharpened end of a sewing pin (about 0.5mm) and very, very quick. I have so far tried washing the keyboard (it's a washable fold-up job), spraying the area with varying brands of home insecticide containing substances ranging from Permethrin to Pyrethrum with no effect. The only thing I have found that nails the little sob's is using my cigarette lighter to burn them off. Would anyone be able to give me some ideas as to what I could be dealing with please? CharlieTheCabbie (talk) 13:35, 3 November 2013 (UTC)

I think somebody was browsing the Cthulhu website recently. :) Wnt (talk) 16:06, 3 November 2013 (UTC)

Seriously though, in a quick search I found some people talking about mold mites [1] - but it's really hard to identify a bug that "looks like a mite" as anything but a mite, without more data. Also, mold mites are up to 0.5 mm in length. [2]. What I'd like to know is: are the mold mites actually breeding inside the keyboard, getting out through some kind of little hole, so that your washing is useless and perhaps it has something else disgusting inside it for them to feed on? Or are they already loose in the house and swarming to the keyboard for warmth or because the smell attracts them or something? (I have no idea if they do that). You have to understand a little about where a bug comes from to get rid of it more than momentarily with an insecticide. Wnt (talk) 16:17, 3 November 2013 (UTC)

Does this "washable, fold-up keyboard" have an "inside" ? If not, then there's no way anything is inside for them to eat, so I'd guess they are eating the material the keyboard is made from itself. StuRat (talk) 16:40, 3 November 2013 (UTC)

It's a keyboard, not a Klein bottle! :) How much does something 0.5mm long need to eat? Wnt (talk) 19:15, 3 November 2013 (UTC)

It needs something 0.1mm long to eat, I imagine. StuRat (talk) 00:14, 4 November 2013 (UTC)

I'm guessing they eat the skin that flakes off when you type, or maybe food crumbs.--Auric talk 23:37, 4 November 2013 (UTC)

The obvious solution is to replace the keyboard. A standard keyboard only costs about $20. You might also try putting the old keyboard in a plastic bag in the freezer. That might kill them off. StuRat (talk) 16:40, 3 November 2013 (UTC)

Does washing them remove some which are replaced by others or do the same ones stay on the keyboard despite attempts to wash them off? Similarly for the acaricides (which doesn't look to be too helpful an article in this case): do they kill some of the mites which are then replaced by others, or are the mites immune? To use an analogy, bailing a boat will only be of limited help if a leak needs fixing.--Wikimedes (talk) 07:04, 4 November 2013 (UTC)

• I am reminded of the movie Akira, for some reason. In any case, how long has this keyboard been in the OP's possession? Unfed baby bedbugs are white, until they turn red. Bedbug adults can last a year without feeding. μηδείς (talk) 03:16, 5 November 2013 (UTC)

I would definitely recommend replacing the keyboard. Beyond that, mites should be unable to cross anything that's been wiped down with mineral oil (you can buy the food grade stuff, completely safe, for rather cheap). So if you can't find another way, wiping the legs of the desk with the oil should prevent them from coming back. I'm curios though as to what the hell they are eating. Have bits of food gotten into the keyboard, by chance? Someguy1221 (talk) 04:57, 5 November 2013 (UTC)

• • Thanks for the suggestions as to what these could be. I managed to get a sample of some of them from the keyboard onto "Sellotape" and took it to my local environmental health office, who have confirmed that they are indeed Mold mites - I have disposed of the keyboard in accordance with both suggestions here and orders from the environmental health service. I have also purchased a container of mineral oil and coated the floor tiles immediately surrounding the desk, and walls of the desk as well as doors (it doesn't have legs). I have been instructed that I shouldn't eat in that room in the future, and I need to keep the temperature down when I'm not in there. Thanks for all your help! CharlieTheCabbie (talk) 16:00, 7 November 2013 (UTC)

River chutes

Another Mississippi River question (guess where I was yesterday :-)

Numerous side channels and oxbow lakes along the Mississippi are named "_____ Chute"; for example, the Grand Tower Chute is an oxbow at about 37°35′38″N 89°29′36″W, Santa Fe Chute separates an island from the main channel at 37°8′26″N 89°24′21″W, and the Island No. 1 Chute is a linear lake paralleling the river at 36°54′30″N 89°5′44″W (be sure to view these in Acme or another topo-map provider). Why are they called "chutes", since they're essentially the opposite of a Chute (gravity)? And is this term used only in the context of the Mississippi River basin? A Google search for <chute river "old channel"> found nothing in other drainage basins. Nyttend (talk) 14:53, 3 November 2013 (UTC)

According to Wiktionary [3] chute is French for waterfall. Recall the Mississippi was at one point claimed by French. Wnt (talk) 15:24, 3 November 2013 (UTC)

Note that river geography changes fairly rapidly, so those "chutes" might have contained small waterfalls, back when they were named. StuRat (talk) 18:47, 3 November 2013 (UTC)

Not particularly applicable, since these are all in flat countryside; the lowest dams and waterfalls are at St Louis, and all of these spots are well below that city. Nyttend (talk) 20:23, 3 November 2013 (UTC)

Check the varying uses of chute and shoot. ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:24, 3 November 2013 (UTC)

The Dictionary of American Regional English labels this usage "lower Missip valley", so it does seem to be confined to that region (the earliest quotation provided is from Mark Twain in the 1850s). The definition offered is "A small sluggish channel, usu[ally] between an island and the main landmass". No information regarding the development of this sense is offered, but one might speculate that the idea of narrowness (think of cattle being driven through a "cattle chute" onto a rail car or into a holding pen) is what's operative, since such a channel is likely to be significantly more narrow than the river's main channel. Deor (talk) 11:35, 4 November 2013 (UTC)

Why does milk make food taste less spicy?

I tried using Google but I wasn't able to find an answer. 65.92.6.107 (talk) 17:13, 3 November 2013 (UTC)

Many spices aren't very water-soluble, but are fat-soluble. Capsaicin from peppers is a prime example. Milk contains fat, unlike most beverages, so is able to dissolve the spices and carry them away from your mouth. StuRat (talk) 18:45, 3 November 2013 (UTC)

According to Capsaicin#Treatment after exposure, the way milk reduces the heat of capsaicin isn't because of milk's fat content, but because caseins (a type of protein) have a detergent effect on capsaicin. Red Act (talk) 01:59, 4 November 2013 (UTC)

Skimmed milk has little fat content, so caseins would be the main component in that case. With whole milk, the effect of the fats may be more important. Ssscienccce (talk) 19:01, 5 November 2013 (UTC)

So is this related to the use of certain types of soaps (maybe "fatty" soaps) in washing oil and grease off one's hands? ←Baseball Bugs ^{What's up, Doc?} carrots→ 00:36, 6 November 2013 (UTC)

Most soaps and detergents are made of chain-like molecules with a hydrophilic (water-soluble) group at one end and a hydrophobic (oily) ‘tail’. They break down the surface tension between oil and water phases, forming an emulsion or a suspension of micelles that can be rinsed away.—Odysseus1479 08:33, 6 November 2013 (UTC)

Impact depth

But the impact depth is the highest possible penetration for a projectile? This sound to me very strange, the strength of the impacted material doesn't play any role?95.252.183.122 (talk) 23:39, 3 November 2013 (UTC)

I've removed the duplicates of this question. Tevildo (talk) 23:41, 3 November 2013 (UTC)

To answer the question, Newton's equation gives the _maximum_ penetration depth for the projectile. If the target is strong enough so as not to exhibit plastic deformation, or if a significant amount of energy is taken up by deformation of the projectile, the depth will be less than predicted by the equation. Tevildo (talk) 23:49, 3 November 2013 (UTC)

Let me add that the stronger the material, the faster the projectile must go before the material behaves as a fluid and the assumptions made in the impact depth formula are valid. Count Iblis (talk) 02:55, 4 November 2013 (UTC)