Wikipedia:Reference desk/Archives/Science/2009 July 30

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July 30

New word phenomenon?

A few months back, I stumbled upon a wikipedia article that explained a phenomenon about when people learn new words (i.e. 'perfunctory') and over the course of the next few days, they see that word more often (i.e. in a book, a newspaper article, billboard on the highway.) What is this effect or phenomenon called? 24.148.59.37 (talk) 02:32, 30 July 2009 (UTC)

It sounds like a form of confirmation bias. Or at least related to it. --Jayron32 04:33, 30 July 2009 (UTC)

It's called Baader-Meinhof phenomenon. --Gwern (contribs) 09:57 30 July 2009 (GMT)

It's not just with new words, either. I remember when I was a kid, when my dad got a new car, suddenly the streets seemed to be full of the same model. It might not even be a cognitive bias, it could just be that since the word is new, it is forefront in your consciousness and seeing it easily reminds you that you just learned it. Over time it falls back to the "just another word" status of everything else in your vocabulary, and seeing it does not trigger the "hey that's that new word" thought. Maelin (Talk | Contribs) 04:39, 30 July 2009 (UTC)

Arnold Zwicky, who blogs at Language Log, has coined (or at least promoted) the term "frequency illusion", which I think is pretty good.--Rallette (talk) 05:19, 30 July 2009 (UTC)

Novel information is kept briefly in short-term memory where it is readily revitalised by chance repetition, then it fades into long-term memory where a trivial recognition is a mundane event. Cuddlyable3 (talk) 19:27, 30 July 2009 (UTC)

Attention is affected by the demand characteristics of the situation. Someone in a book (Sorry, don't recall the author) wrote that he had promised to get a helicopter for the arrival of someone at a charitable event. Thereafter, he seemed to see helicopters wherever he went: arriving, departing, or being transported on a truck. The "Ziegarnik Effect " which I only half remember, comes to mind. A waiter remembers an order in detail, but only until it is served at the table. If you are told that Mr. Colvin will be your new boss, then you seem to hear the name Colvin several times a day. It becomes salient in a way it was not previously. There may be a lexical priming effect, which makes any occurrence of a salient word very noticeable. Edison (talk) 02:01, 31 July 2009 (UTC)

Spider identification

Is this spider found in mid-Missouri an orb spider? Just wondering if I should shoo it off the porch or invite it to stay a while. -- kainaw™ 02:37, 30 July 2009 (UTC)

Yeah, looks like an orb-weaver alright. With these guys, no matter what you do they'll still have your porch for themselves :) . Usually, they would spin a new web every day, you know. --Dr Dima (talk) 05:38, 30 July 2009 (UTC)

Mortality rate relating to refusing blood and/or medical procedure on religious grounds?

I imagine there would be such a statistic but I'm struggling to find it as it's a bit specific. How many people die as a result of refusing to be given blood in a medical emergency for religious reasons? Specifically when doctors believe there was a reasonable chance that blood would have saved them. But less specific any statistic regarding refusal of medical procedure would be helpful. This is not homework or medical advice. Vespine (talk) 04:51, 30 July 2009 (UTC)

A Wikipedia article cites from the May 22, 1994 issue of the Jehovah's Witness magazine Awake, p. 2: "In former times thousands of youths died for putting God first. They are still doing it, only today the drama is played out in hospitals and courtrooms, with blood transfusions the issue." The statistic you seek is unlikely to be given by a reliable medical source because of the legal, technical and ethical issues of the controversy. Cuddlyable3 (talk) 19:16, 30 July 2009 (UTC)

This article is helpful. "Although there are no officially published statistics, it is estimated that about 1,000 Jehovah Witnesses die each year through abstaining from blood transfusions". Axl ¤ [Talk] 20:03, 30 July 2009 (UTC)

Did human muscles mutate to become weaker than those of apes and other animals?

I read recently that human muscles are intrinsically much weaker than those of a chimp, one of whom would have no problem in overpowering a human. The idea was that a mutation during the evolution of humans made such a mutation beneficial, which sounds very odd. But then I thought that perhaps the weaker musculature allows for finer motor control. Apes are great at swinging and leaping around trees, but could they do ballet moves, or juggle balls, or handwrite? And when the technology becomes sophisticated enough, could we opt to reinstitute the more powerful muscle variants, and breed humans who make Arnie look like a wimp. Myles325a (talk) 06:57, 30 July 2009 (UTC)

I think it is natural that we are much weaker than Apes or Chimps, because our survival is not dependent on our strength. This means we naturally get more and more weaker with time due to cross breeding, as weak people survive almost just as well as strong people, much like how that recent study which told women are getting more beautiful over time... With all the medicines available, I think I can safely say that we humans will get more and more weaker over time. Our parts evolve according to our needs, and hence we have hands which can write rather than swing trees with. I'm pretty sure some research is going on in the area to use technology to make us physically stronger, along with scientific research about genes, but I'll leave that bit for others... Rkr1991 ^{(Wanna chat?)} 07:08, 30 July 2009 (UTC)

OP Myles back. I don't know about "get more weaker and weaker", but our grammar appears to be getting worser and worser. Also, the last ape I saw swinging trees was King Kong. Myles325a (talk) 23:58, 30 July 2009 (UTC)

It may be an adaptation for Persistence hunting, very few animals do that and extra muscle would use up a lot of energy. Dmcq (talk) 08:35, 30 July 2009 (UTC)

"[E]volutionary biologist Alan Walker, a professor at Penn State University" came up the the same hypothesis about fine muscle control[1], with the difference being more motor neurons in the spinal cord in humans. AlmostReadytoFly (talk) 08:55, 30 July 2009 (UTC)

A hypothesis that I doubt. Any inhibition would be to stop us hurting our joints I'd have thought. Which is part of the same overall business about why are we being weaker. Anyway he can go ahead and try testing it - that's always good and might turn up something. Dmcq (talk) 10:12, 30 July 2009 (UTC)

That Persistence hunting is really interesting! I like the theory that guided our running and hairless evolution.

Rkr1991,you have told that animal organs evolve according to their needs.It is not so.It is like this- some individuals of the same species develop some mutations which give them a upper hand in survival and competition among the individuals of the same species.They survive better than the other members and the their traits are passed down to their offsprings.Thus we observe evolution.Infact Lamarck also told "organs evolve according to their needs"(the giraffe neck stuff) but was clearly disproven by weismann's 21 time rat's tail cutting experiment.gdsrinivas 15:45, 30 July 2009 (UTC) —Preceding unsigned comment added by Gd iitm (talk • contribs)

OP Myles back. As a Jew, Weismann need not have not have cut off rat's tails. He need only have noted that 3000 years of circumcising Jewish boys has not led to males being born already cut. Myles325a (talk) 23:58, 30 July 2009 (UTC)

(At gdsrinivas) How is the cutting of a rat's tail beneficial for it, to be passed on ? And according to your argument, how exactly did humans develop hands which could write rather than those like the apes' or the chimps' ? Surely, a mutation of this sort wouldn't have helped better in their survival, at the time they were living in caves ? Please explain this. Rkr1991 ^{(Wanna chat?)} 07:44, 31 July 2009 (UTC)

Op myles back here. No, proto humans weren’t writing their memoirs in the caves, but they WERE cutting stone tools and shaping spears and so on. This does need manual dexterity. Cavewomen would have been very impressed with a caveman who had a sure hand and knew how to use it. Myles325a (talk) 06:53, 3 August 2009 (UTC)

As an argument against the extra nerves and control idea have a look at Elephant#Trunk. Lots of nerves don't make them weak. Dmcq (talk) 07:53, 31 July 2009 (UTC)

Eating packing peanuts

Someone on IRC brought up the subject of the om-nom-nommable packing peanuts (fex the starch ones) last night. Now I wouldn't exactly go nomming these as sustenance, but if you were starving to death would these do anything for you? And are they made of pure starch, or is there some sort of additive/filler? One time I was incredibly hungry/bored and ate about six, I didn't get sick or anything, but is this even remotely a good idea? ZS 08:03, 30 July 2009 (UTC)

I was once told they're Cheesy Wotsits without the flavouring and colouring! --TammyMoet (talk) 08:40, 30 July 2009 (UTC)

I seem to recall a previous discussion here on this, but can't be bothered looking in the archives. Anyway, the result I recall was that they are likely to contain rodenticides, insecticides or repellants to prevent them being omnomnommed by bugs or rodents in transit. As a rule, don't eat stuff that isn't food. --203.202.43.54 (talk) 08:58, 30 July 2009 (UTC)

According to this manufacturer's site [2] the starch peanuts won't attract bugs or rodents because "the sugars and any food value" has been removed in processing. Since "any food value" is a rather vague term it makes that source a lot less reliable. Researchers found in this study [3] that bacteria don't grow quite as well in it. Most sources say starch packing peanuts dissolve in water. Except in Raleigh they didn't [4]. Your saliva contains Amylase which, if the experiment suggested here [5] works converts the starch in the peanuts to sugar. This patent for making them [6] mentions on page 4, line 23 that manufacturers may use additives in starch packing peanuts. This patent identifies such additives as dyes, processing aids and anti static products [7] Given that ordinary foodstuff also sometimes contains questionable ingredients you may be o.k. to nibble some packaging occasionally. You can't sue the manufacturer if this turns out to be overly optimistic, though. (Definitely don't eat any pink ones. Those are the ones with antistatic additives.) Gwen may be happy to learn that at least one source on the web [8] thought they were safe for ferrets if they didn't eat too many.:-) 71.236.26.74 (talk) 19:37, 30 July 2009 (UTC)

There are people who consider it their moral duty to eat these peanuts when they're done with them. See [9]. I have no idea how serious these people are. Dcoetzee 04:08, 31 July 2009 (UTC)

Are there really 32 AA batteries hidden inside a 6V lantern battery?

See this youtube video. Is this truth or hoax? There are a few more vids on Youtube of people opening up lantern batteries, finding something completely different inside and claiming that the AA batteries claim is a hoax. But there are loads of different brands of lantern battery on the market, so could it be that batteries made by different companies have different contents? --84.70.227.184 (talk) 09:50, 30 July 2009 (UTC)

Snopes says it's a hoax, which is a good start. There's a pretty obvious cut in the video just before the contents are visible, suggesting the small batteries were added then. AndrewWTaylor (talk) 11:04, 30 July 2009 (UTC)

Usually there are four F cells inside. F cells are like D cells except an inch or so longer. Some brands just have four D cells plus some empty space. There are holders you can get that let you use your own D cells, which is cheaper. 70.90.174.101 (talk) 11:07, 30 July 2009 (UTC)

FWIW, an A23 battery can be peeled open to reveal 8 usable 1.5V button cells. Also, some 9V (i.e. 'square') batteries contain six AAAA batteries. Any others that people know of? --Kurt Shaped Box (talk) 12:04, 30 July 2009 (UTC)

32 AA batteries would be 48V not 6V. It would be horribly inefficient to make 6v batteries this way -- Mad031683 (talk) 18:26, 30 July 2009 (UTC)

Not necessarily. It depends on the way they are connected. Kotiwalo (talk) 18:28, 30 July 2009 (UTC)

The battery in the hoax video above is a “Heavy Duty Powercell”, which is sold by Walgreen’s. In this video, you can see the exact same brand of 6V battery, opened up to show the 4 F cells inside. Note that the hoax video contains “cuts”, which makes it easy for the hoax producers to remove the real contents of the battery, and replace it with the 32 AA cells. In contrast, the real video shows the entire disassembly process, with no cuts. Also, in the hoax video, you can see that the top of the battery does not contain any metallic contacts that the top layer of AA batteries would make contact with, so those batteries can’t be a part of a real circuit. Red Act (talk) 18:41, 30 July 2009 (UTC)

The thing is that an individual 'cell' can only produce 1.5 volts. So to make a 6v or 12v battery - you need 4 or 8 cells wired in series. If you want higher capacity (more amp-hours), then it makes more sense to use bigger cells than to wire a bunch of little cells in parallel. Also, there is a problem with wiring 'dry cell' batteries in parallel: Because the manufacturing tolerences of these individual cells aren't precise, it's likely that some of the cells will start to run down before the others. When the voltage drops on one cell that's wired in parallel with another - there is a net voltage difference that will cause current to flow from the cell that still has power into the one that's failing. Since these are not rechargeable, that current has to go someplace - and what it does is to turn into heat. Net result is that if you tried to make a LARGE 6v battery from 32 AA's, you'd need four sets of 8 cells - with each group wired in parallel and the four groups hooked up in series to get up to 6 volts. Then as one cell started to run down, all seven of the other AA's would start to drive current into it and that one weaker cell would overheat very rapidly - and probably even explode. This is NOT a good thing! Hence, they don't do that. Using 4 F-cells works fine because all four can be wired in series to get up to 6volts without any need to wire them in parallel. SteveBaker (talk) 00:47, 31 July 2009 (UTC)

I agree with Steve. 1.5 volt cells in parallel is asking for trouble. Make your cells large enough for the current demand, then place enough in series for the voltage requirement. Then there will be no current out of each cell when the external circuit is open. Edison (talk) 01:52, 31 July 2009 (UTC)

Waking up on falling

So I've noticed that when I take a ferret out of its cage when it is sound asleep, and I carry it around or breath on its nose, it takes a good half minute or so before they're really awake - which is reasonable enough. But if I were to take the same ferret and toss it in the air and catch it, it seems to wake up instantly halfway up.

Which makes me wonder: would the same thing happen for a human who is suddenly falling? If it would, then perhaps the best alarm clock would be a bed hoisted by ropes, which fell at the set time! Is this the passing vagary of a demented mind, or a possibly cool project to try out sometime? --Gwern (contribs) 09:55 30 July 2009 (GMT)

I'm glad I'm not one of your ferrets. Don't toss them in the air to wake them. That's not nice. Theresa Knott | token threats 10:36, 30 July 2009 (UTC)

A lesson is learned but the damage is irreversible! But seriously, now that I know this about ferrets I rather want to know about humans as well. --Gwern (contribs) 10:55 30 July 2009 (GMT)

Finding that your house is on fire will also wake you up immediately. Or seeing your bed surrounded by gunmen. Or getting thrown into a pool. Lova Falk (talk) 10:56, 30 July 2009 (UTC)

Sure, but all three of those are a bit hard to arrange cheaply & easy, and one might get used to the gunmen. Falling could probably be arranged with some rope and tinkering, and I don't think one would easily get used to it. --Gwern (contribs) 11:02 30 July 2009 (GMT)

It must be possible to get used to falling. Astronauts experience a constant sensation of falling, but they're able to sleep with no problem. APL (talk) 13:15, 30 July 2009 (UTC)

That's true, but they are "falling" even as they are falling (sorry) asleep, so it doesn't wake them up. A sudden fall I would think would be hard to get used to, since you have been stationary for some time before the bed drops you. —Akrabbim^talk 16:43, 30 July 2009 (UTC)

That's a good point; they may not sleep well, but they do sleep. But I doubt you could get used just by a few seconds a day - otherwise rollercoaster fans would quickly be bored by any free fall! --Gwern (contribs) 16:55 30 July 2009 (GMT)

Of course, it would probably vary by the person, and how routinely tired they are when waking up. I have accidentally trained myself to reflexively turn off a very obnoxious alarm clock without ever waking up. Now I use my cell-phone alarm across the room that forces me to get out of bed to turn it off. For me, falling would probably wake me up, but I would very easily fall back to sleep considering I would still be comfortably in bed after the fall. After falling asleep again a few times, I think it would get to the point where I would just not wake up, like with my first alarm.

That is just me, so it would probably work pretty well who don't have trouble getting out of bed but don't get woken up by just a loud noise. —Akrabbim^talk 17:15, 30 July 2009 (UTC)

What would get both you and your ferrets going would probably be a Fight-or-flight response and the adrenaline that is released in the process. If one could really train one's body to ignore the fact it is falling it might be dangerous because you would fail to wake up sufficiently to figure out whether you were heading for fluffy pillows, a bramble bush or solid concrete. 71.236.26.74 (talk) 17:34, 30 July 2009 (UTC)

I have personal experience with falling while asleep. When I was a kid, I had the top bunk of a bunk bed. I fell out several times and I didn't actually wake up until after I hit the floor. Admittedly I wasn't in the air long, but I don't remember the sensation of falling, only the jolt and the pain from hitting the floor. I also recall a news story about someone who sleepwalked and fell from a building but never woke up even after hitting the ground. Until I can find it though, I am skeptical. Sifaka ^talk 17:40, 30 July 2009 (UTC)

My alarm clock goes with me wherever I travel, it fits in a small bag and works in any guestroom. Please explain how a contraption of ropes and pulleys that generates a local earthquake is better than my alarm clock. Cuddlyable3 (talk) 18:39, 30 July 2009 (UTC)

In this context "best" obviously means "most likely to wake you up." APL (talk) 20:25, 30 July 2009 (UTC)

What APL said, and I'd note that there are groups for whom regular alarm clocks don't work, period. For example, one such group I belong to would be the hard of hearing. We generally use vibrating alarm clocks; mine works reasonably well, but still takes me a while to wake up.

Also, half the justification for this project is that it's geeky and weird! (One would think Wikipedians would be sympathetic to that impulse.) --Gwern (contribs) 07:09 31 July 2009 (GMT)

Sifaka, what are the chances of someone waking up after falling off the building? Unless it was a rather short building, this might make it quite likely that they didn't wake up. Nyttend (talk) 21:49, 30 July 2009 (UTC)

That would be sleeping The Big Sleep. Cuddlyable3 (talk) 23:13, 31 July 2009 (UTC)

Found the story! "A German teenager accidentally climbed out of a fourth-floor window and fell 10 meters to the ground where he kept on sleeping, albeit with a broken arm and leg." Sifaka ^talk 01:28, 31 July 2009 (UTC)

A teenager. That explains it. Those things can sleep through anything. Googlemeister (talk) 13:57, 3 August 2009 (UTC)

Global stress meter

A couple of years ago I read an article about something like global stress meter technology. According to the article the meter consists of about a hundred devices scattered around the globe. The devices continuously log the people's mood variations of the surrounding area, and the results are combined to form a graph. The article had a picture of one of the graphs, showing a clear peak at September 2001. The magazine I read this from is rather reliable, although not specialized in scientific content. Now I ask you, is this real, and if it is, how on earth does it work? Kotiwalo (talk) 10:05, 30 July 2009 (UTC)

One way to measure “global stress” in the sense that you mean the term is with a series of surveys, such as the International Business Owner Surveys.[10] Another form of “global stress” really is measured with physical devices, namely the stress field of the Earth’s crust.[11] But there is no physical device for measuring the amount of emotional stress felt by a large group of people in the vicinity of the device. Red Act (talk) 13:19, 30 July 2009 (UTC)

I never heard of such a thing but I don't think it would be too difficult to build something like that. A microphone and a compuer to tell if peoples voices were losing the high frequencies for instance and just stick it in a shopping centre. Or I believe some people are now trying to detect people who are stressed at airports by using a camera and analysing their movements - that sort of thing probably could be used much more reliably for overall stress in a crowd. The other possibility I can think of is it is some sort of development of the Scientology scam with E-meters. Dmcq (talk) 14:17, 30 July 2009 (UTC)

Then there's http://www.moodyornot.com which, admittedly, is very self-selective! Tonywalton ^Talk 14:24, 30 July 2009 (UTC)

Thanks for answers, everyone. No, they were (according to the article) small devices, about a hundred of which were produced, that could detect anxiety and tension and other varieties of mental activity on the local area. These devices were scattered over the world to provide the most accurate possible global mood. But it doesn't seem feasible to me either. The graph that was shown on the article could have been made without any input from such devices, everyone knows that global stress should leap when something disturbing happens. Unless someone recognizes this as something real, I am satisfied. Thank you for your answers. Kotiwalo (talk) 14:31, 30 July 2009 (UTC)

Global Consciousness Project.--Shantavira|^{feed me} 14:44, 30 July 2009 (UTC)

In case it isn’t obvious, the Global Consciousness Project is solidly within the realm of pseudoscience. The devices that project uses are just random number generators, and don’t actually measure people’s mood variations. Red Act (talk) 15:22, 30 July 2009 (UTC)

Actually I think it had something to do with the RNG. I'm going to check the article. Thanks! Kotiwalo (talk) 10:21, 31 July 2009 (UTC)

That's it! That's the thing I was looking for. But I still wonder whether it's real. I guess we can't know. Kotiwalo (talk) 10:23, 31 July 2009 (UTC)

Stock markets give an index of mood. A global index-of-indicies (of which at least one exists although I dont remember the details) would give a global mood index. 78.144.197.8 (talk) 17:07, 30 July 2009 (UTC)

The stock market measures mood - but mixed up with a lot of other variables. I don't think you could call that reliable. This thing is a hoax...there is no way to do what they claim. Even asking people how they feel is unreliable. SteveBaker (talk) 00:39, 31 July 2009 (UTC)

I thought of stock market myself, but it is a special type of mood I suppose. Kotiwalo (talk) 10:21, 31 July 2009 (UTC)

With modern internet and social network websites providing plentiful information, I wonder why the designers chose to feed "random" input into this worldwide sensor grid? Actual data can be fed in and processed, if they seek a real result. The presupposition that a random number generator would be influenced by "mood" is totally preposterous - if any such mechanism were discovered, I think we would conclude that the random number generator was defective, and that it was actually a predictable, controllable system that was receiving input of some form. I'm curious what proposed mechanism exists to couple the random number electronics with "mood" - again, if such a mechanism exists, it should be nonrandom and repeatable. This project is very pseudoscientific. Nimur (talk) 15:50, 31 July 2009 (UTC)

The reason the designers aren’t using real data is because the designers have no interest at all in developing a global mood index. The whole point of the “experiment” is to try to prove that “psychic energy” or whatever can affect hardware random number generators.

I personally don’t have any problem in principle with people doing a science experiment to test whether some phenomenon exists, even if there is no known mechanism by which the phenomenon could occur according to currently accepted scientific theory. Indeed, that description would describe the circumstances under which the Geiger–Marsden experiment was performed. In that experiment, there was no good reason to test for large-angle deflections of the beam, based on the then-accepted plum pudding model of the atom. What makes the Global Consciousness Project pseudoscientific bullshit is the methodology used, not the subject matter.

It would be possible for the Global Consciousness Project to do an actual, valid science experiment to test if global mood can affect random number generators, requiring essentially no more time or money than what those people have already invested. For example, they could hypothesize before the experiment that there will be a correlation between the moodyornot.com percentile on a given day, and the average values of the numbers created with those random number generators on that day. After making that hypothesis, they would then gather data for a predetermined large number of days, and then test for a correlation, using all the data they collected.

Unfortunately, the GCP people have chosen to avoid a reasonable scientific methodology like that, and instead retrospectively cherry-pick little bits of their data at carefully chosen times, based on their subjective ideas of what the global mood should be in specific instances that they’ve chosen, in such a way that it will make what they’re trying to prove look valid. The project suffers from a severe case of selection bias, making their “results” completely meaningless. Red Act (talk) 17:52, 31 July 2009 (UTC)

Perpetual motion from electrolysis of water under high pressure?

I have come to the conclusion that the electrolysis of water under high pressure must take more energy than for water under low pressure, since if water in a very deep lake (lets say five miles deep) was converted into hydrogen and oxygen at the same efficiency as normal pressure, this could fill a float with a cable (or drive a turbine) to generate electricity on its rise to the surface, the water could be recycled and further energy gained by using the hydrogen and oxygen in a fuel cell -though this would be less then the energy used in electrolysis, but combined with the "flotation generator" energy, would provide more than enough to repeat the cycle. Unless this really is a scheme for perpetual motion, which I doubt,what would actually happen? —Preceding unsigned comment added by Trevor Loughlin (talk • contribs) 10:21, 30 July 2009 (UTC)

Pressure doesn't really have anything to do with it. You could have a pressurised champer that only allowed in water at normal pressure. I think you will find that the answer is because of heat. What you are saying would eventually make the water cooler and cooler and more and more energy would be needed for electrolysis.--58.111.132.76 (talk) 12:23, 30 July 2009 (UTC)

What I would expect is that the standard electrochemical potential would increase as the water pressure increases since hydrogen and oxygen at pressure are at higher energy than when they are at low pressure. This would offset the extra energy obtainable from the gases being at depth.

However if it doesn't do this, the maybe it could form a perpetual motion machine. However the variation of electrochemical potential is well known (there are well known equations describing it as well), and I wouldn't expect any net energy gain.83.100.250.79 (talk) 13:22, 30 July 2009 (UTC)

Only an experiment could prove or disprove this - an experiment measuring the voltage required for electrolysis at different depths.83.100.250.79 (talk) 13:25, 30 July 2009 (UTC)

See this. It is estimated that there is 5% reduction in power needed for electrolysis of water under high pressure. That is, of course, an estimate. Any actual implementation will likely be less efficient due to numerous other factors. -- kainaw™ 13:51, 30 July 2009 (UTC)

Although it's been published I'd tend to ignore that in relevence to the original question-- (actually it doesn't really seem to have anything to do with the original question..)

The process can be split into two steps:

H+ + e- >>> 1/2 H2 (absorbed on electrode) no real volume change - chemical potential independent of pressure

and

 H2 (absorbed on electrode) >>> H2 (gas free under pressure) increase in volume therefore increase in energy(work) required as pressure increases

The same applies for the production of oxygen.

The usually accepted view is the the increased pressure will increase the energy required for elecrolysis - offsetting any extratable amount to make both equal. That's just one of the standard thermodynamic principles - ie that energy can't be made from nothing.

I can't think of a reason why this would change in this example - so I think it wouldn't be a perpetual motion machine. If it does turn out to be different then that would require a lot of explaining. The second equation above is the reason why mor energy is required for electrolysis at higher pressures. (edited once)83.100.250.79 (talk) 14:30, 30 July 2009 (UTC)

Casimir effect-flotation in a vacuum?

Could the low energy cavity between two fixed Casimir plates lead to both plates floating upwards even in a vacuum if made of a very light metal such as lithium? Would the low energy be equivalent to a lightweight gas balloon under normal atmospheric pressure, or for that matter the proposed "vacuum balloon" under normal pressure? Could such a small force be measured if it existed?Trevor Loughlin (talk) 10:29, 30 July 2009 (UTC)

Wouldn't the Casimir effect push the plates outward from each other, and not 'up' or 'down'? --Gwern (contribs) 10:38 30 July 2009 (GMT)

Normally, but the plates would be fixed in place to prevent this. I just wondered if a "more then vacuum" would float like a balloon in a normal vacuum. Probably a silly question since it compares energy density to gas density, no doubt entirely different. —Preceding unsigned comment added by Trevor Loughlin (talk • contribs) 11:09, 30 July 2009 (UTC)

Well, if the plates are fixed, then nothing will happen. If you put yourself between two walls fastened together, and push outwards, the walls will go nowhere if they're really 'fixed'. The net force would be negative. And consider the symmetry: if we have the 2 parallel plates - || - that we need, which direction would they hypothetically go? There ought to be a unique direction, but that's rather asymmetrical.

A 'v' shape might work, but I think what would happen is the forces in the wider part would cancel the forces in the narrow part, although it'd take a physics guy to say exactly what happens there. If a 'v' shape could work that way, it seems suspiciously like perpetual motion... --Gwern (contribs) 11:30 30 July 2009 (GMT)

Read Newton's laws of motion#Newton's third law: law of reciprocal actions to see why that's not possible. Dauto (talk) 15:14, 30 July 2009 (UTC)

ammonium stearate??? Ammonium distrate

In the TV series 24 episode 5, Jack Bauer "flushes" people out of their safe room, by creating a poisonous gas with the help of ammonium and something else he found in the kitchen. Does anybody know which substances he mixed and what was the name of the poisonous mixture (ammonium stearate???) Does anybody know what substances he mixed in order to create "ammonium distrate"? Lova Falk (talk) 10:49, 30 July 2009 (UTC)

Ammonium Stearate is a compound, I don't know what else "distrate" could be, but "distrate" is not a chemical term.

Mixing any ammonium compound including ammonium stearate with an alkali (base) produces ammonia which woul force most people out of a room.83.100.250.79 (talk) 13:13, 30 July 2009 (UTC)

According to [http://www.pesticideinfo.org/Detail_Product.jsp?REG_NR=00183900086&DIST_NR=048733 this] "Distrate" appears to be a pesticide containing alkyl dimethylbenzyl ammonium chloride and alkyl dimethylethylbenzyl ammonium chloride. This is listed as acutely toxic, carcinogenic, a developmental toxin and an endocrine disruptor. Probably not something you'd find in the average kitchen. sometimes used as a disinfectant. Please do not try mixing things with things at home - remember, 24 is fictional! Tonywalton ^Talk 14:37, 30 July 2009 (UTC)

Actually the listing you gave says it's effects are not known with certainty, except that it is poisonous to aquatic life.

(edited twice due to error) However mixing this with an alkai (eg sodium carbonate or sodium hydroxide) would not do anything under these conditions

It's basically a strong detergent.83.100.250.79 (talk) 14:51, 30 July 2009 (UTC)

Here's a list of things that contain the same compound(s) [12]

There's a risk assesment here [13] (long article!) - There doesn't seem to be any such reaction that could clear out a room - probably just "hollywood chemistry" aka 'bull' ...83.100.250.79 (talk) 15:01, 30 July 2009 (UTC)

I can't see any reaction that would work.83.100.250.79 (talk) 15:05, 30 July 2009 (UTC)

The makers of TV shows often are very "creative" when the characters are making bombs or poisons. This is simply to protect the viewers. It is very possible that either the mixture doesn't work at all or is much less effective than portrayed. Sometimes the explosive materials are not revealed at all. Kotiwalo (talk) 15:15, 30 July 2009 (UTC)

No need to make it easy. One of my children read a chemistry textbook and then went off an mixed up something from chemicals round the house that produced a poisonous gas and I had to open the doors and windows to get rid of it. Good understanding of the chemistry but not much sense. Dmcq (talk) 20:12, 30 July 2009 (UTC)

Sorry about that. Luckily in this case what jack bauer did doesn't seem to work. It's actually surprising how difficult it is to mix up something toxic in the home - despite the wide variety of chemicals in the garage, and kitchen.. There's actually a way to make hydrazine in the home very easily. (not telling) - and bleach should probably be banned...83.100.250.79 (talk) 20:49, 30 July 2009 (UTC) I spent most of my years from 12 to 20 trying to do just the same... probably a common story.83.100.250.79 (talk) 20:50, 30 July 2009 (UTC)

If you want to drive people out of a room using common household chemicals, simply mix ammonia and clorine bleach. This releases clorine gas in dangerous quantities, and clorine gas is really irritating to eyes and lungs even in small quantities. DO NOT TRY THIS, even in small amounts, as an experiment, except in a well-equiped laboratory under an exhaust hood. Unfortunately, quite a few people do this "experiment" by accident every year, usually by using first ammonia and then bleach, or vice versa, while trying to remove stains from a toilet bowl. -Arch dude (talk) 23:49, 30 July 2009 (UTC)

"Phase shifts" in brain and IQ

What exactly is going on during the "phase shift" described in the article here? http://www.newscientist.com/article/mg20227141.200-disorderly-genius-how-chaos-drives-the-brain.html?full=true It seems very important as an extra 1 millisecond is said to give a 20 point increase in IQ. 78.149.172.96 (talk) 11:52, 30 July 2009 (UTC)

It sounds like a bad analogy to complexity theory with handwavey, inaccurate terminology. There have been numerous attempts to describe the brain or the mind as a "chaotic" system in the past, but they range from "stretches of terminology" to "wild speculation and making stuff up." Nimur (talk) 15:09, 30 July 2009 (UTC)

The article describes research into how ideas, and hence intelligence, arises in the brain. The model and terms used are similar to the engineering of a regenerative radio receiver where forming an idea is analogous to tuning in to a particular transmission frequency out of many. The idea is that there are two energy states in the brain: 1) an incoherent or chaotic state where energy is dissipated at random comparably to thermal noise in a radio, and 2) a particular thought gains critical mass (or in the terms of the NS article triggers a sand avalanche). The latter event is proposed to correspond to a particular frequency and phase of resonance in neurological activity. The significance of one frequency and phase is that it is a unique focus for accumulating energy. Random energies at other frequencies and even at the same frequency but a different phase do not contribute to the resonance. They represent chaotic thoughts that become imperceptible as the significant resonance takes hold. These speculations suppose that there is a mechanism in the brain for collecting energy at a unique frequency and phase, with some correlation to intelligence, which the researchers report having detected. The significance of "an extra millisecond" could be that longer time taken to integrate a frequency achieves better elimination of noise. Compare that with a chess player taking extra time to decide a difficult move.

However while this frequency-selective model lends itself to pretty simulations on video the reported data is not convincing. Only 17 children were tested for EEG activity and IQ. Their IQ spread is not stated. 1 millisecond may correspond to a large or an insignificant phase change depending on the frequency concerned. I am doubtful when I read that 1 ms longer in one brain state increases IQ and 1 ms shorter in the other brain state increases it by a different amount. Cuddlyable3 (talk) 17:51, 30 July 2009 (UTC)

The abstract linked to says "The electroencephalogram (EEG) was recorded from 19 scalp locations from 378 subjects ranging in age from 5 years to 17.6 years." So the journalist or someone had made a mistake - it was 378 children, not 17. 78.146.235.174 (talk) 10:58, 31 July 2009 (UTC)

I was thinking that the "phase" was something like the phases of water (solid, liquid, gas) or phase of regular or chaotic rather than a phase in the electronic sense. I recall the AI technique of Simulated annealing. The phase shift could be when a lot of things are thrown together at random, some of which catch on as new ideas. The longer this random phase, the more random throwing together of things, the more of the problem-space is searched. Tell me if you disagree. 78.146.235.174 (talk) 10:47, 31 July 2009 (UTC)

In the context of brainwave frequency measured in Hz it looks like phase must mean phase angle, especially when the terminology is "phase shift" not "phase change". We read "..the brain often synchronises large groups of neurons to fire at the same frequency, a process called 'phase-locking'." Simulated annealing can regularise crystal structures but is not AFAIK an established technique for artificial intelligence. Cuddlyable3 (talk) 23:05, 31 July 2009 (UTC)

Yes it is - one of the oldest. I thought the Wikipedia article was rather narrow. 84.13.58.55 (talk) 13:25, 1 August 2009 (UTC)

Simulated annealing is a numerical technique used to solve many "poorly conditioned" mathematical problems (including the physical crystallization simulation that gives it its name). Many artificial intelligence problems can be put into a form such that simulated annealing returns the numerically optimal solution. Nimur (talk) 21:15, 2 August 2009 (UTC)

Saddle joints

Hi everyone I'm having trouble understanding how a saddle joint works. I understand the diagrams I have seen showing a concave surface sitting in a convex surface; but I just can't see in my mind how this works in the carpometacarpal joint of the thumb. I've looked at the external links listed in the 'saddle joint' article and I even have a copy of Gray's anatomy right next to me but I just don't 'get' it. The article on saddle joints states that the saddle joints are capable of flexion and extension, abduction and adduction and circumduction. Perhaps I don't understand because I don't know what flexion/extension or abduction/adduction of the thumb looks like. One other thing about saddle joints that I don't get is that I can move my thumb up, down, left and right and can spin it round in a circle (which I believe is circumduction). These are all things that a ball and socket joint can also do. The article on saddle joints says that they have no axial rotation, which I believe a ball and socket joint does have. What would be different about our thumbs if they had axial rotation? Basically what I'm asking is what would be different about our thumbs if a ball and socket joint held them in place instead of a saddle joint? Hope this makes sense; as you can probably tell I'm rather confused about saddle joints. Thanks in advance to anyone who helps. RichYPE (talk) 18:47, 30 July 2009 (UTC)

If you had a ball and socket thumb you'd be able to twist your thumb (around it's length - like a door knob turns)

The saddle joint moves like a universal joint (a bit less flexible) (but not attached to something that can rotate) - are you familiar with those?83.100.250.79 (talk) 19:18, 30 July 2009 (UTC)

Compare this image http://www.heumann.org/body.of.knowledge/a8/rdts45.gif with that a universal joint - can you see how if one end turns the other end must also turn. - With a ball and socket joint the other end doesn't turn... (did that help - or just more confused ?!?

Also looking at the image again - note that the two surfaces are the same - imagine how they can move against one another, and how far they can move. The thumb joint will be less simple - but it is 'the same'83.100.250.79 (talk) 19:23, 30 July 2009 (UTC)

Practical problem - something light and compact to stand on

What could I use to stand on that will raise me about two feet in the air? The criteria are that it must be light enough and compact enough to be carried by hand on public transport for some time, and that there is not enough time to do major woodworking for example. It can lean against a wall like a ladder while I am standing on it, although a ladder itself would be too big. I only need to stand on it for about a minute. I would prefer something that's cheap enough to dispose of after I've used it. 78.144.197.8 (talk) 19:27, 30 July 2009 (UTC)

A plastic rubbish bin / trash can should do the trick, depending on your weight, of course. --Cookatoo.ergo.ZooM (talk) 19:37, 30 July 2009 (UTC)

It would be rather an ordeal to take a wheelie bin with me on public transport. A chair would be too big too. 78.144.197.8 (talk) 19:39, 30 July 2009 (UTC)

See if you can find s.th. like this [14] Try your local home improvement box or a store for supplies for the elderly, a kitchen store might also carry s.th. similar. 71.236.26.74 (talk) 19:48, 30 July 2009 (UTC)

That would be ideal if I had one already, but I'd rather not pay a lot just for one use for less than a minute. I've been thinking that perhaps I could strengthen a cardboard box somehow, which could be folded flat to carry. Other design possibilities would be three pieces of wood to form a thin "A" shape, or two sheets of something in an "X" shape with another sheet on top to stand on. I'm still looking. 78.144.197.8 (talk) 20:20, 30 July 2009 (UTC)

I was thinking the same. You probably need two cardboard boxes - one to be the shell, the second the reenforcement. Cut up the second so you have diagonal bits which will fit into the first, with each diagonal cut with a half-width cut half way down. That way they slot together to make an X shape, which will brace the shell box. This, including the shell box, can be collapsed and folded during transit (a roll of parcel tape will help reassembly, but shouldn't be necessary). If further support is required, more sheets of the donor box cut with slits at either (horizontal) edge, so they can be looped around and slotted into themselves, forming tube(ish) structures - put these tubes in between the arms of the X both to hold weight and to prevent it from folding sideways. -- Finlay McWalter • Talk 20:26, 30 July 2009 (UTC)

Finlay is on the right track. Go to your local wines&spirits store, and get three empty booze boxes. They are heavyweight (usually "triple-wall") corrugated cardboard, and usually have the interlocking cardboard pieces called an "egg crate" inside, to keep the bottles from rubbing on each other during shipping.

Carefully chosen, you should be able to get two that stack on each other quite nicely. Use the third one as a step to get up on the stack of two. Good luck! --DaHorsesMouth (talk) 22:42, 30 July 2009 (UTC)

How about a pair of stilts? SteveBaker (talk) 00:34, 31 July 2009 (UTC)

Have you seen the film Tommy? Check out the character played by Elton John. 87.81.230.195 (talk) 00:40, 31 July 2009 (UTC)

And now for the real question: what are you going to be doing for a minute that needs you to be two feet taller? (If you are going to be lifting something heavy or firing a weapon, for example, you might have to consider strength of materials and their stability. This is not just idle curiousity, but most of it is.) // BL \\ (talk) 01:12, 31 July 2009 (UTC)

For being seen while making an address to the public, a Soapbox is classic. Edison (talk) 01:47, 31 July 2009 (UTC)

Wow, all these baroque solutions. All you need is a folding two-step ladder, which you can buy at any decent home supply store. Looie496 (talk) 03:53, 31 July 2009 (UTC)

Apart from a folding two step ladder being not compact, not light, not cheap, and not disposable. Didnt you even read the title? 78.146.235.174 (talk) 11:08, 31 July 2009 (UTC)

A folding chair would work just as well. 98.234.126.251 (talk) 05:25, 31 July 2009 (UTC)

Ah, but the OP said they didn't want to buy a set of steps for such a brief use. I assume they couldn't borrow one from a friend or neighbour? AlmostReadytoFly (talk) 08:09, 31 July 2009 (UTC)

A soapbox would be more traditional. SteveBaker (talk) 13:41, 31 July 2009 (UTC)

Would it cause an echo ...echo....echo? Edison (talk) 15:10, 31 July 2009 (UTC)

Go to a local convenience store, they'll probably have scads of milk crates out back. Ask the people who work there if you can have a couple, they most likely won't mind if you take them. Milk crates are strong as hell, light, and stackable. Plus you can carry your tools in them.

In the end I used a sturdy bucket turned upside down, although it was not 2ft high. 78.147.244.14 (talk) 15:21, 2 August 2009 (UTC)

For a women to lose weight after pregnancy

How long does this takr women to lose most of extra weight after when a baby is born. Average woen is still overweight over even 5 month after the baby is born. Like a english teacher at school, she got her baby in late January, and the teacher temporaily on intermission absence shows up every week in June, and her face is now as wide as a honeydew melon, and I made girls upset by criticizing the teacher by her weight. Until how long after the baby will average women lose extra weight. 9 month?--69.228.145.50 (talk) 21:19, 30 July 2009 (UTC)

I'm not sure where you live, but where I live, openly criticizing any woman for being overweight, especially when other women can hear you, is considered extremely rude and socially just unacceptable. And if it's after a pregnancy, then your comments are way out of bounds. (At least, where I live they are.) The speed of weight loss is highly variable and depends on hormone levels and whether she is breastfeeding, as well as the usual factors of exercise and diet. Trying to slam back to the previous weight could be harmful to both the mother and child. So, knock off making comments like that. Tempshill (talk) 21:37, 30 July 2009 (UTC)

A very wide face can sometimes be moon face, which can have a variety of causes, some of which are very serious. I suggest you apologize to your teacher and make some efforts at becoming a more compassionate human being. --Sean 14:11, 31 July 2009 (UTC)

To add some balance to the critique of the op's conduct, I doubt he actually said it to her face. And in any case, we're talking about a school environment here, almost anything goes. The condescending devilry of the responses will probably not be appreciated. —Preceding unsigned comment added by 92.8.113.198 (talk) 01:11, 1 August 2009 (UTC)

According to the OP, other people found it offensive as well, so I doubt it's fair to say 'anything goes'. Indeed there's no evidence that anyone but the OP thought it was an acceptable thing to say. Just because the OP is perhaps unaware of norms in human communication doesn't mean we should accuse the OPs peers and every other school child of having the same issue. Indeed if I was one of the OPs peers I would be deeply offended by the insinuation Nil Einne (talk) 03:12, 1 August 2009 (UTC)

But more to the point none of us have any right to hell him how he conducts himself. When people ask questions they want answers not to be lectured on their manners. This isn't finishing school. —Preceding unsigned comment added by 92.19.119.89 (talk) 22:44, 2 August 2009 (UTC)

The article pregnancy quotes The National Health Service that recommends that overall weight gain during the 9 month period for women who start pregnancy with normal weight be 10 to 12 kilograms (22–26 lb). Some of this increase is fat that will be used to produce milk for breastfeeding. After childbirth, eating disturbances such as loss of appetite can be symptoms of postnatal depression. This may be simply "Baby Blues" but medical advice should certainly be sought from a doctor, not Wikipedia. Weight loss is highly variable among lactating women.Cuddlyable3 (talk) 12:56, 1 August 2009 (UTC)

homemade radiation treatment of food without cooking

Can a low-power dose of defrosting microwave radiation prolong the life of refrigerated (non-frozen) meats or milk without significantly affecting taste quality? If this is not so, is there any type of radiation treatment that would kill bacteria without cooking the food? Are there plasmid-attacking agents that would be harmful to bacterial DNA but not harm human cells once in the digestive tract? John Riemann Soong (talk) 22:01, 30 July 2009 (UTC)

The thing with Food irradiation is it uses ionising radiation to damage the bacteria. Microwaves are not ionising radiation, so I doubt they'd do more than slightly warm the food. Looking at the doses used, they're pretty high (kiloGrays), so I don't think you could do it at home. AlmostReadytoFly (talk) 22:14, 30 July 2009 (UTC)

As AlmostReady just said, you need ionizing radiation (X-ray or gamma) and not microwave radiation to sterilize food. And, moreover, you need extremely high doses of ionizing radiation. To be precise, you need doses high enough to damage every living cell, every bacterium or spore, in the food product to be preserved. And the radiation doses required to do so are astonishingly high, orders of magnitude higher than those sufficient to kill a human. Some bacteria - notably Deinococcus radiodurans and some others mentioned in D. radiodurans article - are especially good at surviving irradiation. --Dr Dima (talk) 22:27, 30 July 2009 (UTC)

Now, on the second part of your question, there are certainly ways to preserve food without actually cooking it. Preserving food with salt is very common. Fermentation is another way of preserving food, by actually using some (normally harmless) bacteria to produce chemicals that kill or inhibit growth of other microorganisms. We have an entire article devoted to Food preservation. There are also antimicrobial chemicals defined as food preservatives, which may be what you are looking for. --Dr Dima (talk) 22:44, 30 July 2009 (UTC)

Actually I'm looking at preserving milk and fresh meat ... yeah I use vinegar and pickling techniques but I'm just looking if there's anything to extend the life of refrigerated (non-frozen) stuff. John Riemann Soong (talk) 04:31, 31 July 2009 (UTC)

Ultraviolet light is used to purify water. It acts by ionizing (irradiating) the DNA of organisms in the water. Ultraviolet light can also be used for food processing. Axl ¤ [Talk] 23:44, 30 July 2009 (UTC)

For preserves and juices they sometimes use high pressure, but "at least 10 MPa" [15] is probably way above what zoning regulation and code would let you have at home. 71.236.26.74 (talk) 23:54, 30 July 2009 (UTC)

And of course for UV to work, the thing you're trying to preserve has to be transparent to UV light (which isn't always the same thing as "transparent"!)...so for most things, you'll only kill the bacteria on the surface. SteveBaker (talk) 00:19, 31 July 2009 (UTC)

What about delaying effects? Like giving it extra storage life for a few more days, etc. John Riemann Soong (talk) 05:02, 31 July 2009 (UTC)

It's hard to believe that you mentioned milk and no one brought up pasteurization yet. Dragons flight (talk) 05:11, 31 July 2009 (UTC)

I assume homemade pasteurisation is difficult? And what about repeated pasteurisation? John Riemann Soong (talk) 05:16, 31 July 2009 (UTC)

Actually, you can get a similar effect (though not as good as commercial methods), by microwaving milk just long enough to get it to ~70 C and then removing it quickly and placing it in a cold water bath to rapidly cool it back down. It's a trial and error thing though because if the milk boils (100 C) you will have ruined the taste/composition. The time required will depend on the volume of milk and the intensity of your microwave. Also, any pasteurization process will still have some effect on the taste, whether the difference if important to you is a matter of personal taste I suppose. Dragons flight (talk) 05:31, 31 July 2009 (UTC)

And for meat, you can try salting it or cold-smoking it. Also, pasteurizing temperature is 80 C, not 70 C as Dragonsflight said. 98.234.126.251 (talk) 05:35, 31 July 2009 (UTC)

The USDA standard is 72 C. It varies a bit by country. Dragons flight (talk) 05:38, 31 July 2009 (UTC)

I really don't think we should be recommending using a microwave to pasteurize milk (or anything else for that matter). The heating is far too uneven. In order to get the entire container of milk to the desired temperature and keep it there for long enough to kill the bacteria, some parts of the milk will be getting up towards the temperature that it'll start to 'cook' and taste funny - while other parts are either not hot enough - or don't get hot enough for long enough. You need a much more controllable heat - and you need to keep the liquid stirring so that it doesn't develop hot spots or retain cooler areas in which bacteria can survive. If you don't kill all of the bacteria - then the ones that escaped will recolonize the parts of the milk that you sucessfully pasteurized. This happens rather quickly - and then you'll be back to square one. SteveBaker (talk) 13:27, 31 July 2009 (UTC)

The most delicious way to preserve meat is to make a confit. --Sean 14:11, 31 July 2009 (UTC)

What about a double boiler? I use it to made homemade evaporated milk, so I figure that also pasteurises it... John Riemann Soong (talk) 08:04, 1 August 2009 (UTC)

Yeah, that can work too -- we use a similar setup in the lab when we want to heat something up without getting up to 100 C, and it can reach 80 C no problemo (but not any higher than that), so in this case that's a wonderful choice! 98.234.126.251 (talk) 08:21, 1 August 2009 (UTC)

On second thought, a Bain-marie would be an even better choice. 98.234.126.251 (talk) 08:25, 1 August 2009 (UTC)