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January 12

Cyanide

Hello, I was wondering how long it takes for cyanide to kill someone. I know that it bonds to an enzyme and disrupts the electron transport chain, but I can't find anything that clarifies the time frame. Thanks so much. Best, Keilana^talk 01:41, 12 January 2008 (UTC)

• I can't find anything on pure CN, but Hydrogen cyanide takes "several minutes" to induce unconsciousness and kills in about half an hour. --M@rēino 02:58, 12 January 2008 (UTC)

• But that's an advocacy site and referring to death in a specific situation. If you look under hydrogen cyanide you'll find a link to this OSHA page, which says "Death can occur within seconds or minutes of the inhalation of high concentrations of hydrogen cyanide gas." So the action of the poison is very fast. --Anonymous, 05:39 UTC, January 12, 2008.

• • The OSHA link is down right now....--M@rēino 18:03, 12 January 2008 (UTC)

• • If you are talking about potassium cyanide.Look here How fast can potassium cyanide kill you ..Mike robert —Preceding comment was added at 19:22, 12 January 2008 (UTC)

There was a case where a guy got arrested by police and took a 'bottle of coca-cola' with him into the police car. He drank it, and died the next day. The levels of cyanide in his body were 16 times the 'lethal dose', proving that the lethal doses that doctors talk about are a joke. --ChokinBako (talk) 22:38, 12 January 2008 (UTC)

Well, no; it really doesn't. "Lethal dose" is usually expressed as LD50 or something similar, and is a purely statistical measure, with often arbitrary or completely unapparent time-dependence. Someguy1221 (talk) 22:42, 12 January 2008 (UTC)

...if this will help, I know this jewler guy who has been killed 7 or 8 times by cyanide. —Preceding unsigned comment added by 71.100.12.59 (talk) 02:08, 13 January 2008 (UTC)

I have another question...the articles on the cyanide compounds say that it has a bitter-almond smell; does this mean that it has a bitter-almond taste as well? And also, is it soluble in alcohol? --71.117.34.195 (talk) 20:09, 13 January 2008 (UTC)

Water vapor

Would a planet have to have sufficient gravity to retain water vapor in order for life to exist (develop from elements in the Universe). —Preceding unsigned comment added by 71.100.12.59 (talk) 12:40, 12 January 2008 (UTC)

Read Alternative biochemistry and Origin of water on Earth if you haven't yet. Life could also exist in liquid water beneath ice e. g. on Europa (moon). For water to exist in roughly constant amounts for billions on a planet, the evaporation or sublimation rate has to be low enough, gravity has to be high enough, temperature has to be low enough, and replenishment (e. g. by comets) has to be high enough. The escape rate of the water vapor depends on the fraction of molecules which reach escape velocity in the Maxwell distribution (and don't collide with other molecules on their way out). Icek (talk) 15:00, 12 January 2008 (UTC)

Procedures for the Laboratory Synthesis of Polymers

What is the most effective way to synthesise polyacrylamide in the laboratory (that is, without radical activators etc.)? Is this most simply acheived by heating acrylamide, perhaps with an alkali, or is there a better way in which the unsafe monomer can be entirely avoided? Thanks very much. Similarly, is there a way to synthesise Kevlar effectively in the laboratory? 86.137.168.61 (talk) 14:35, 12 January 2008 (UTC)

Radical activator is necessary, with a lot of luck you can use UV light to start the reaction. Ionic activation is also possible, but for polyacrylamide not the mest method. H₂SO₄ or NaOH should start also polymerisation, which might result in opaque polymer. Kevlar synthesis is more difficult, because it is not a radical polymerisation, but a polycondensation. The mixing ratio of 1:1 and a the use of acid chloride or ester as starting material is difficult if you can not use high temperature high pressure polymerisation.--Stone (talk) 15:35, 12 January 2008 (UTC)

I don't think the phrase "that is" means what you think it means. Polyacrylamide is routinely synthesized in the laboratory with radical activators. SDS-PAGE (the 'PA' stands for 'polyacrylamide') uses ammonium persulfate (with the help of TEMED) as a radical initiator to form polyacrylamide. It's as simple as mixing acrylamide & water with APS & TEMED - ~10-30 minutes later you have polyacryamide. It's simple enough that barely trained people do it routinely in molecular biology labs. I'm not sure about residual unpolymerized monomer, but molecular biologists have been working with the stuff for years - I'm sure there is literature out there looking at that. If you want more info, you may want to say more about what you're going to be doing with the polyacrylamide, and why you'd have problems using a radical activator. -- 128.104.112.236 (talk) 20:01, 12 January 2008 (UTC)

Thanks so far. I had heard that most of the methods with a radical activator needed unpractically high pressures in particular; but, if this is not the case, it should be hopeful with ammonium persulfate and TEMED - do you know the details of this, please? I need a solution in glycerine for a demonstration of N3, and there is no major concern about residual monomer, but it may have been a consideration if there were many different methods. 86.137.168.61 (talk) 22:02, 12 January 2008 (UTC)

Not sure where you heard that "most methods with a radical activator need unpractically high pressures". If the monomer is a liquid (like acrylamide), the reaction will be at atmospheric pressure. Delmlsfan (talk) 04:11, 13 January 2008 (UTC)

Food protein in blood plasma

Related to a previous question of mine, I found this abstract of an article describing experiments with the uptake of oral bromelain. It says that the plasma half life is 6 to 9 hours and the plasma concentration was 5 ng/ml after 48 hours of "oral multidosing (3 g/day)". If one (unrealistically) assumes that the intake was continuous over 48 hours and has reached saturation and the elimination is proportional to the concentration (i. e. like the exponential decay law), then 18 ppm of the original protein make it into the plasma. The real figure could be a bit higher due to the equilibrium not having been reached. Does anyone more knowledgeable know more about that? E. g. is that only valid for bromelain but quite different for other proteins? Icek (talk) 14:38, 12 January 2008 (UTC)

Metabolism (Not really a medical question)

I was wondering which of the two would be a better boost for metabolism: running 3 miles twice a day (morning and night) or running 6 miles once a day? Just a light question about energy/calories/metabolism/etc, not looking for real medical advice here. Any "gut feeling" responses welcome! Thanks. Sappysap (talk) 15:37, 12 January 2008 (UTC)

I'd lean towards the 2 shorter workouts because you'll get nearly double the amount of the post-workout metabolic increase (where you continue to burn calories after you stop running). Check [[1]] and metabolism Furmanj (talk) 17:02, 12 January 2008 (UTC)

What if two black holes were near eachother?

Would they both combine? —Preceding unsigned comment added by 24.118.5.243 (talk) 20:56, 12 January 2008 (UTC)

Black holes could orbit eachother (or just fly past eachother) as can any other astronomical bodies. It is also hypothesized that black holes can collide and combine into a single, larger black hole. Such an impact would generate massive gravitational waves, which Kip Thorne claims would carry away 10% of the Black holes' masses. Physicists hope that LIGO and LISA will be able to detect these waves, giving more details on the exact nature of such collisions. Someguy1221 (talk) 22:11, 12 January 2008 (UTC)

• The History Channel's "Universe" program just did a bit on this. It basically backs up with Someguy1221 says above -- they could orbit each other, fly past each other, or combine. Which, if you think about it, is also your top three possibilities for just about any two heavenly bodies that come near each other. --M@rēino 17:44, 13 January 2008 (UTC)

Also, see this SkyAndTelescope article about two black holes that are each heavier than the black hole at the centre of the milky way that are about to collide, one of them is millions of times heavier than the sun and one is billions of times heavier. They are having shorter and shorter orbits around each other, and could collide in about 10,000 years. Many people are expecting them to merge, although they could release massive gravitational waves, but they might not be at the right frequence to detect. Hope this helps. Thanks. ~AH1^(TCU) 00:25, 17 January 2008 (UTC)

Alcohol through a straw

Hello, Wikipedia-type-people. Quick and painful: Corollary to this - how and why does drinking alcohol (be it beer or wine) through a straw would get one drunk faster (than drinking the same normally)? This is just my morbid curiosity. Thank you in advance. Cheers, Ouro (blah blah) 20:59, 12 January 2008 (UTC)

I've actually never heard of this, but the only thing that comes to me is that my friend's dad, who is a toxicologist, told us that you can speed up the metabolism of alcohol by breathing deeper. This is the only thing I can think of that relates to this, where you probably intake less oxygen when drinking with a straw. Other than that, I have no clue. --Wirbelwindヴィルヴェルヴィント (talk) 21:35, 12 January 2008 (UTC)

My suggestion would be -- suggestion. But I don't have any special knowledge about it. --Trovatore (talk) 21:36, 12 January 2008 (UTC)

The most common (pseudo)scientific explanations offered is that by sucking on a straw:

• An oral vacuum is created, in these circumstances the boiling point of alcohol drops and more alcohol vapors are created in the straw and mouth. These are inhaled in the lungs, meaning more alcohol can get into the blood faster than by drinking it the normal way.
• Alcohol gets into the mouth through a straw in very narrow jets, meaning it has a larger surface to volume ratio as it enters the oral cavity. As a result more alcohol can evaporate before it is swallowed and thus it gets in the bloodstream quicker.

While they make some theoretical sense, I'm not sure I buy them practically (for example, is there enough of a vacuum to lower the boiling point of ethanol sufficiently for a significant amount to vaporise at oral temperatures? Does the jet of alcohol the comes through the straw remain long enough for the surface area to have a significant effect? If so, wouldn't a thinner straw work better than a thicker straw?) Rockpocket 00:04, 13 January 2008 (UTC)

Thank you, Ouro, for suggesting some inebriating WP:OR, to be conducted in the service of humankind and the eternal quest of Wikipedia for omniscience. BTW, are you a North Pole or a South Pole ? --Cookatoo.ergo.ZooM (talk) 01:44, 13 January 2008 (UTC)

There may be no direct correlation, just that women often drink their alcohol with a straw, and men do not. Women on average take less alcohol to be affected. So the typical straw sucking alcohol drinker will get drunker quicker, because she is a woman. Graeme Bartlett (talk) 04:22, 13 January 2008 (UTC)

Graeme, your suggestion fits the atmosphere here at WP:RD the best ;) truthfully - I didn't think it mattered how you did it. Research is definitely called for here. Oh, and Cookatoo - I'm neither - much more a cosmopole if I'd be allowed a mediocre semi-successful pun. Cheers, Ouro (blah blah) 07:19, 13 January 2008 (UTC)

This question has been posed several times here before, but I can't find it in the archives. One proposal I've heard is that using a straw allows one to drink more/faster/more-potently because of less awareness of the actual drinking (quick straw-to-throat so less taste and more rapid swallowing possible than if mouthfuls). But I agree, more Original Research is needed. DMacks (talk) 16:49, 13 January 2008 (UTC)

For what it's worth, alcohol (and, in general, other intoxicating substances) tends to have lots of myths surrounding it. Dunno why, but you'll find any number of people who are convinced of things like "Vodka gets me drunk fast, but I can drink whiskey all nite". There's no obviously plausible explanation for this, but many people believe it. Friday (talk) 16:51, 13 January 2008 (UTC)

A surprising amount of your ability to get drunk is not to do with your body but your mind. If you tell someone they are drinking very strong tasteless alcoholic beverage (when you are actually giving them water) then there is a pretty good chance they will start acting as though they are drunk. I am unsure if they will have a hangover in the morning though. TheGreatZorko (talk) 14:51, 16 January 2008 (UTC)

There is also a possibility that drinking alcoholic beverages through a straw can also cause damage to brain cells ( ect ). this is due to the rush of alcohol into the blood stream through the oxygen which quickly enters the brain. this could alternatively lead to possible long term brain damage and possible tumours. this has also been found in certain alcohol poison incidents which could be fatal.

REMEMBER DRINK RESPONSIBLY.

Weather Balloons

I was curious is there any regulations about launching Weather Balloons and if so what are the regulations regarding thier payload? THank you. 67.125.159.70 (talk) 22:33, 12 January 2008 (UTC)

IANAL, but I'm pretty sure this is going to vary from place to place. What jurisdiction are you interested in? Algebraist 23:01, 12 January 2008 (UTC)

IP traces to Los Angeles, in the United States. --Ouro (blah blah) 07:40, 13 January 2008 (UTC)

I have no doubt that there are regulations of some kind, in most or all jurisdictions. In some of his recorded lectures, Walter Lewin discusses his experiences launching similar balloons for X-ray astronomy in the Australian outback. He states that they had to end the flight (dropping the payload on a parachute, with the balloon breaking up in the upper atmosphere) before the balloon flew over the more populated parts of the country. -- Coneslayer (talk) 20:20, 15 January 2008 (UTC)

You may consider contacting the FAA and asking them what restrictions may apply. The rules can be fairly involved, so I'm not sure we can provide an explicit answer. Someguy1221 (talk) 20:29, 15 January 2008 (UTC)

Not to mention if something goes wrong and the FBI break into your house looking for the terrorist, you're probably better off telling them you called the FAA and followed their instructions rather then telling them you asked on the wikipedia reference desk. Nil Einne (talk) 22:52, 15 January 2008 (UTC)

If you are in the UK that would be the Civil Aviation Authority you should consult.--TreeSmiler (talk) 01:28, 16 January 2008 (UTC)

January 13

Help! I have woodlice in my house!

Every morning, when I wake up, there are woodlice all over the floors of the rooms in my house. A lot of woodlice. Possibly thousands. What's the best way to get rid of them completely? They're getting in my food, congregating in my bath (they're not coming up through the drain - I've checked) and getting on my mattress now and it's really beginning to piss me off.

I've tried putting down woodlice powder, which has killed quite a few (but not enough to make a dent in their numbers). I have filled in just about every crack, hole, nook and cranny I can find at floor level that I've seen them retreating into (but it doesn't seem to have stopped them getting in). I also go around with my vacuum cleaner, sucking up as many as I can before they skitter away, to very little effect.

Any DIY tips? I don't think that I'll be able to afford an exterminator. —Preceding unsigned comment added by 81.76.46.10 (talk) 00:32, 13 January 2008 (UTC)

Sorry, don't have an answer; just a remark on the things you learn from WP. I had expected something much more disgusting to answer to the name woodlouse -- who knew it's just a roly-poly. --Trovatore (talk) 03:58, 13 January 2008 (UTC)

• I'd check out what the Broxtowe Borough Council has to say. In short -- you're doing the right thing by repairing all the cracks and holes in your home, but there must still be a source of moisture in your house. If you've had similar problems in the past, like mold or rotting wood, then you probably need to buy a dehumidifier. Wood lice don't cause much problems, but lots of little nasties like moisture, and soon you'll have to be prepared to shell out the cash for exterminators or home repairs. --M@rēino 04:20, 13 January 2008 (UTC)

If you can dehumidify, the woodlice should die, as their gills need moisture (actually, that sounds like a less pleasant method of death than a bug spray). We get a few during the year in the basement, along with millipedes in the fall, which have the same physiological limitation. However, I agree with Mareino - if you've got these in quantity, I'd watch out for other problems related to excess moisture. J. Spencer (talk) 05:07, 13 January 2008 (UTC)

Sodium bicarbonate is also supposed to be effective. But you really need to deal with the dampness problem or find their nest(s).--Shantavira|^{feed me} 10:16, 13 January 2008 (UTC)

Do you have partition walls? A friend of mine (with a damp flat) had woodlice living and breeding *inside* his PWs. The structure inside the wall was some sort of honeycombed cardboard - which the 'lice seemed to love. Check there. --Kurt Shaped Box (talk) 12:39, 13 January 2008 (UTC)

Maybe you could raise a family of Dysderidae. jeffjon (talk) 15:55, 14 January 2008 (UTC)

And then, maybe set up a colony of wrens. 79.66.24.40 (talk) 23:30, 15 January 2008 (UTC)

See the dead spider

I knew an old lady who swallowed a cat. Imagine that, to swallow a cat! --Trovatore (talk) 00:09, 16 January 2008 (UTC)

Mercalli scale

what are the countries that is using mercalli scale for measuring earthquakes —Preceding unsigned comment added by 124.217.98.24 (talk) 05:08, 13 January 2008 (UTC)

Any country can use it. A lot of people seem to think that the difference between the Mercalli scale and the Richter scale is like the difference between the metric system and traditional Anglo-American measurements -- different scales to measure the same thing. It's not. The Mercalli scale measures the local intensity of an earthquake -- how much shaking is felt at a given place. The Richter scale, and other measures of magnitude, measure the total size of the temblor. These are two completely different things. --Trovatore (talk) 05:38, 13 January 2008 (UTC)

Seismologists now universally use the Moment magnitude scale. Only the press use the Richter scale now.--TreeSmiler (talk) 10:00, 13 January 2008 (UTC)

Well, but it's calibrated to agree with the Richter scale pretty closely in most situations, so that's a second-order issue. Probably the labs report moment magnitude and the press reports the same number and calls it "Richter" for familiarity to the public. --Trovatore (talk) 21:52, 13 January 2008 (UTC)

Methysergide

Methysergide is the N-alkyl derivative of Lysergamide or not? Please help. —Preceding unsigned comment added by Gcllau (talk • contribs) 05:12, 13 January 2008 (UTC)

We have pages about both Methysergide and Lysergamide. That latter page is actually about a whole family of related structures, so you can see what the differences are, what the features of your particular compound of interest are, etc. DMacks (talk) 16:38, 13 January 2008 (UTC)

Compare Ergine (lysergamide) with methysergide. You could say that methysergide is a substituted lysergamide (i.e. it carries the additional 1-methyl and N^amide-(2-propan-1-ol) groups. —Preceding unsigned comment added by Cacycle (talk • contribs) 00:00, 14 January 2008 (UTC)

The problem is that whether the (2-propan-1-ol) is considered to come within the meaning of Alkyl (-CH3) derivative? Please help. Gcllau (talk) 13:55, 14 January 2008 (UTC)

molecular weight

What is the unit (ug??, etc) of the molecular weight? Gcllau (talk) 05:48, 13 January 2008 (UTC)

According to our article molecular weight, it is the unified atomic mass unit. DuncanHill (talk) 05:58, 13 January 2008 (UTC)

typically in grams/mole (g/mol) Furmanj (talk) 15:45, 13 January 2008 (UTC)

...which, in biochemistry, often gets called a dalton (symbol: Da). The molecular weights of proteins, protein complexes, and other heavy structures are often expressed in units of kilodaltons (kDa, a thousand grams per mole) or megadaltons (MDa, a million grams per mole) for convenience. TenOfAllTrades(talk) 16:41, 13 January 2008 (UTC)

• per the OUP Concise Science Dictionary, (1984, p. 54) the dalton or atomic mass unit is equal to 1.66033 x 10^-27kg. DuncanHill (talk) 16:46, 13 January 2008 (UTC)

Obesity/popular culture

Cross-posting with Wikipedia:Reference desk/Humanities

For some time I've been working on the obesity article. It contains a commonsense but entirely original research section on the place of obesity in popular culture. I cannot imagine there are no academic sources that deal with this question, but I have had great difficulty in finding the most suitable (and accessible) sources on this topic. Would anyone know of a source that deals with this reliably? JFW | T@lk 06:59, 13 January 2008 (UTC)

Hmm, maybe there's some interesting references Category:Obesity; Super Size Me is very popular, but culture not so much. --Ouro (blah blah) 07:36, 13 January 2008 (UTC)

This is also in the other place: ":For scholarly articles on obesity in popular culture see list at [2]." Still, I haven't read them. Julia Rossi (talk) 08:44, 13 January 2008 (UTC)

Guys, these are things I have already done. I was thinking more about a respected textbook or article in a social sciences journal. I am sure these things exist, but using Wikipedia as a self-reference is not really useful and the Google Scholar search turned out garbage. JFW | T@lk 10:29, 13 January 2008 (UTC)

I'm not sure what you are looking for. Possible starting point in the literature: Portrayals of Overweight and Obese Individuals on Commercial Television. --JWSchmidt (talk) 17:38, 13 January 2008 (UTC)

Does light stop at the surfaces it's reflected from?

I'm sure there's a sensible answer to this, but when a ball bounces straight back off a wall, its velocity is zero at the point at which it changes trajectory. Why isn't this true of photons reflected off a mirror?

Thanks Adambrowne666 (talk) 11:32, 13 January 2008 (UTC)

The reflected photon is not the same entity as the incident photon. One photon gets absorbed, then another one gets emitted. See Reflection (physics). At the moment of reflection, the photon doesn't exist at all, so it doesn't have a velocity. --Heron (talk) 12:06, 13 January 2008 (UTC)

Uh, weird - thanks Adambrowne666 (talk) 22:09, 13 January 2008 (UTC)

Weird indeed - this may help your understanding. hydnjo talk 01:35, 14 January 2008 (UTC)

I wondered if this might be a question that comes up periodically, like the one about infinitely stiff materials transmitting information faster than light. Thanks for your answers, which make sense in the way so much quantum stuff does - it feels like someone's fudging something somewhere - like nature is jury-rigging arbitrary fix-its to cover up problems it didn't think of when it started off, and hoping no one will notice because it's down at such a micro level... Adambrowne666 (talk) 10:34, 14 January 2008 (UTC)

We don't have an article on circlons. They're mentioned in the article and are a key component to that theory...so shouldn't we? --71.98.14.236 (talk) 17:43, 14 January 2008 (UTC)

We don't have that article because (to my knowledge) they are not an accepted physical explanation for the phenomenon (outside of that site; note its domain name). The standard theory describing such interactions is quantum electrodynamics. --Tardis (talk) 17:53, 14 January 2008 (UTC)

Oh, thank you very much for the info! --71.98.14.236 (talk) 04:04, 15 January 2008 (UTC)

Precisely how do baleen whales exist during the many months they abstain from eating?

Many species of baleen whales spend part of the year feeding on krill etc in the rich polar waters, putting on multiple tons of blubber. They then spend many months away from this food source -- the grey whale migration is thousands of kms, the longest of any mammal. Other large animals that go without food for long periods of time (e.g. some bears) hibernate, so their body systems shut down to some extent. But these whales are mightily exerting themselves, swimming, and of course in many cases pregnant or lactating. How do whales do it? How does their digestive system switch from working on food to working on fat, so completely, for such a long time? And then back again, year after year for up to 100 years? If humans tried this sort of yoyo dieting we'd screw up our metabolism. What mechanisms kick in for cetaceans? —Preceding unsigned comment added by BrainyBabe (talk • contribs) 12:32, 13 January 2008 (UTC) Sorry I meant to sign that. BrainyBabe (talk) 12:33, 13 January 2008 (UTC)

Yo-yo dieting is key here. For the whales the feeding is not necessarily followed by abstaining. The sequences are part of a cycle with a long trajectory built in. For humans who feed largely in a frequent browsing/grazing way, to mess with the cycle in a polarising, all-or-nothing way puts stress on the system. If a whale were to miss out on one of those shrimp feeds my guess is they'd be in big trouble. There's also an economy of input, output and sustainability level that maybe could be compared – somewhere. Julia Rossi (talk) 08:33, 14 January 2008 (UTC)

Microwave cooking

When cooking soup in a microwave oven, I've noticed that time taken to heat a given volume of soup depends on the shape of the container. I'm guessing the effect is caused by having a surface area exposed to the microwaves, but the heating times are the opposite of those you'd expect - a mug of soup (low surface area) heats very quickly, frequently boiling over before the 2 minute recommended time is up, while a shallow dish of soup, which has a much greater surface area, doesn't get above lukewarm unless heated continually for several (up to 5) minutes. So what causes this effect? Laïka 19:04, 13 January 2008 (UTC)

My first guess would be that the microwaves are horizontal. Therefore you need to consider the surface area of the 'walls'. 81.93.102.185 (talk) 20:21, 13 January 2008 (UTC)

To a first approximation, all of the microwave energy is absorbed in the water if you are using an acceptable container. In an uncovered shallow container, you lose more of that heat in evaporation before the water boils because of the much larger surface area. If you put a top on the shallow container, teh time should be about the same: for instance, put a saucer on top of the soup bowl-- faster and less wasteful than using plastic wrap. -Arch dude (talk) 21:18, 13 January 2008 (UTC)

tweaking a pellet fired boiler

I was nice and toasty warm and happy thanks to my oil fired boiler and radiant heating system—until i found that it was using nine gallons (34 L) of heating oil per day. That rate of consumption is likely less than that of Al Gore's jet aircraft, but is probably more than my fair share of contribution to a few global problems we are having at the moment (not to mention just a tad bit expensive). We've now switched to burning wood pellets, after repairing an abandoned feed system (late '80s vintage?, no instruction manual or even a manufacturer's nameplate) and making a few plumbing and wiring adjustment which i'm sure helped to reduce fuel usage, i was able to raise the building temperature from 40 F (4.5 C) back to the toasty warm 68 F (20 C) using only 30 lbs (13.6 kg) of pellets while the outside temperature averaged 20 F (6.7 C).

This was seemingly a spectacular gain in efficiency, until i reconnected all the thermostats and allowed the system to run unsupervised (starting at toasty warm) during a fairly mild 24 hours—and burned up 160 lbs (73 kg) of pellets. The pellet manufacturer claims 8.6 MBtu per pound (4,115 kJ/kg), that's 1,376 MBtu (1,452 MJ) in a day, ten percent more than the 1,251 MB (1,320 MJ) the nasty old oil was inputting to the boiler.

I should have seen a healthy jump in efficiency, i reduced the heated area by around 25 percent and lowered the temperature of the water which gets pumped to the radiators, but did not. This leads me to believe that either we were in fact burning more oil than i thought (possible, it was all free, leftovers in a tank that needed emptying so it can be moved, i wasn't really paying attention until i had to buy it, and other excuses) or the pellet combustion is horribly out of kilter and needs some adjustment. A few temperature sensors and a computer to measure, control, and record boiler output, HVAC calculations, more and better insulation, and improved zoning etc. are all projects for this summer. Here's what i can control right now for a more economical and earth friendly remainder of the winter:

• firing rate The boiler is rated at 585 MBtu (617 MJ) per hour, the oil burner was supplying 556 MBtu (587 MJ) an hour, and with a duty cycle of about five minutes of firing and around eight not (very approximate, again i wasn't paying attention) was maintaining the water temperature between 202 and 208 F (95–98 C). When the auger on the pellet system is turning, it meters fuel at a constant rate of 44 lbs (20 kg) an hour, but is connected to a repeat cycle timer to control feed rate. The electro-mechanical timer that was present on the system was set for 12 minutes of on time and either 30 or 42 minutes of off time, since the mechanical part no longer ticks i can't tell which. The replacement timer was designed to be adjustable from 0 to 30 minutes of on time and 0 to 60 minutes of off time, but in actual operation has a maximum on time of one minute. With a few more rolls of solder from RadioShack i might be able fix this problem, but would prefer not to mess with the limited success i've had so far. It is now set for 1 minute on and 2.5 minutes off for a firing rate of 108 MBtu (114 MJ) per hour and with a boiler heating cycle of around 30 minutes on and 20 off (varies much more than when burning oil) maintains the boiler's water temperature between 160 and 166 F (71–74 C).

• forced air supply and draft The pellet feed system has a blower with a single speed motor which delivers air to the burn pot. It was wired in such a way that it only operated while the pellet auger was turning, and the intake was completely closed off providing very little air. That didn't look quite right, during the on time the pellets would burn with a weak orange flame and during the off time would smoulder and produce black smoke. Pellets would overflow the burn pot and make a mess. I rewired so that the blower would provide continuous air during the boiler heating cycle, and by loosening a screw and shoving a wedge under a cover plate i have some fine-grained control over the air supply. There is now a nice bright yellow flame around the edges of the burn pot, bright red glowing pellets, and a nice jet engine sound when the boiler door is open. I've been able to find a bunch of information on how to get maximum efficiency from an oil fired boiler with natural draft—measure flue temperatures and CO₂ percent and adjust the draft accordingly. I have no way handy of measuring these values, and have no idea what they should be when using forced draft and burning pellets. When the oil burner was operating i could place the palm of one hand against the flue near the exit from the boiler for only a few seconds. With pellets the flue is barely warm at the beginning of a cycle, and near the end i can hold my hand at the exit for around 20 seconds.

• boiler water temperature i've lowered this from a maximum of 208 F (98 C) to 166 F (74 C). I think lowering this temperature should only improve efficiency, and it should be set as low as possible—too low and it will take too long to heat up the building in the morning—too high and the boiler room and crawlspaces with distribution lines get warmer than they should.

Any ideas on how to adjust the system for more efficient combustion? If you have a pellet stove, what color is the flame? Is there any smoke? Don't worry about any of the safety aspects of this question. It's a boiler, but only produces hot water and not steam, there's a functioning pressure relief valve and a thermostat to prevent explosions. Too much forced air and not enough draft would force hot gasses through the pellet feed system and eventually ignite the hopper, but the fire department is less than a block away, the chief lives next door, i'm a member, and a hopper fire would make a big mess but would not spread to the rest of the building anyway.—eric 22:04, 13 January 2008 (UTC)

Subatomic particles

Here is a question: does an electron love a proton, or does it love a neutron? NeonMerlin 22:38, 13 January 2008 (UTC)

Electrons love protons, and barely notice that neutrons exist. However, protons can only accept so much love. Someguy1221 (talk) 22:42, 13 January 2008 (UTC)

WOW! I wish my prof explained it that way!  ;-) hydnjo talk 23:41, 13 January 2008 (UTC)

Yes, and when electrons get excited, they ejaculate photons! Ironic though that the less excited they are the closer they are to their lovers. Or is it? Root⁴(one) 04:26, 16 January 2008 (UTC)

And now I don't want to know what electron capture or neutron decomposition would be... Someguy1221 (talk) 04:38, 16 January 2008 (UTC)

January 14

Why does food taste delicious?

If a kind of pizza evolved that was really bad-tasting, nobody would eat it, so it would eventually dominate all kinds of pizza cause those kinds would run out, you know? So why doesn't that happen in nature? Everything tastes so delicous! It's just begging to be eaten by predators! Like lettuce.. it's buttery and sweet and goes great with a strong vinaigrette. Why doesn't it get edged out by a spiny lettuce that gives you indigestion? --f f r o t h 00:06, 14 January 2008 (UTC)

Many yummy foods actually exist to be eaten. More specifically, they contain seeds that are sufficiently robust to survive attempts at being eaten, either because they are too hard to consume (think peach pits) or because they don't mind passing through the digestive tract of their naturally occuring consumers (think watermelon seeds). The act of being eaten (or trying to eat) helps the plant by moving the seeds farther from the parent. Such dispersal can increase the odds that some of the seeds will eventually find furtile ground. If you just dump your seeds year after year on the same spot, that will generally do little to advance the species.

That said, other plants, including lettuce, do not have seeds in their yummy parts. I don't know what advantage (if any) lettuce gains by being yummy. I will however note that iceberg lettuce and some other varieties were actually bred by man from ancestors that were comparatively bitter. Dragons flight (talk) 00:28, 14 January 2008 (UTC)

Whatever function iceberg lettuce may have, it's certainly not to taste good. Someone once opined that there's nothing wrong with the stuff; it had just been misidentified: It's not a food, but rather a building material. Something along the lines of fiberglass insulation.

I'll take a pure arugula salad--without even any oil, if ncessary--over iceberg any day of the week. --Trovatore (talk) 05:34, 14 January 2008 (UTC)

Vegetables store energy and nutrients for the plant. Like plants, animals require energy and nutrients, so out bodies have evolved to appreciate their taste. Nevertheless, plants do make efforts to make their nutrient stores unattractive, making tannins and alkaloids, spines and thorns to discourage animals from eating them. The reason so many of the plants we eat today appear, on the face of it, to be so evolutionarily disadvantaged is because they are. We made then nice and tasty by selective breeding, breeding out the bitter chemicals, the spines and the selecting for the juicy flesh. Wild vegetables are very different from the cultivars we eat today. Rockpocket 00:49, 14 January 2008 (UTC)

moreover, if a kind of pizza was bad tasting, it would remain on the shelf till midnight, yes. But would Dominoes make the same pizza again the next day? Kushal^t 01:04, 14 January 2008 (UTC)

Yes of course. Dominoes make bad pizza every day. And hundreds of times a day. All their pizza is terrible, at least in Australia. Rfwoolf (talk) 05:26, 14 January 2008 (UTC)

It doesn't surprise me that dominoes make bad pizza. But who would think to make pizza out of dominoes in the first place? --Trovatore (talk) 02:48, 17 January 2008 (UTC)

I think that you'll find that most of the deliciousness is the product of thousands of years of artificial selection. Wild variants of most of the things in your salad would not be nearly as yummy. This is why animals are so interested in getting into your garden. There isn't anything nearly that yummy on their side of the fence. APL (talk) 01:07, 14 January 2008 (UTC)

Unfortunately, taste is not the only selective factor in the history of cultivation. Other aspects, such as yield, climate and disease resistance, or preservability got factored in as well. In my opinion, wild strawberries taste so much better than those big watery blobs sold at grocers. The same goes for other berries, not to mention the variety and tastes of wild-growing mushrooms compared to shiitake and champignons. </rant> ---Sluzzelin talk 02:15, 14 January 2008 (UTC)

There are also many examples of symbiosis between the vegetable and animal kingdoms. For instance, consider navel oranges and clementines. These plants have, most paradoxically, disevolved their own ability to independently reproduce. Yet this peculiar adaptation ends up conferring such an advantage in tastiness that certain animals are willing to artificially reproduce the plants for them, in order to enjoy fruit without seeds. Paradoxically, the seedless varieties end up reproducing more profligately than their seedful brethren, and are thus selected for (at least in the niche consisting of tended orchards). —Steve Summit (talk) 02:12, 14 January 2008 (UTC)

The reason those plants dont get edged out is that the gardeners pull out the horrible tasting stuff, like dandelions, summer grass, couch, wire weed, spurge etc that for example shows up in my vege plot. I leave the tomato and lettuce plants. But rabbits come and eat the lettuce! Graeme Bartlett (talk) 06:25, 14 January 2008 (UTC)

Dandelion greens aren't horrible tasting!--The Fat Man Who Never Came Back (talk) 06:32, 14 January 2008 (UTC)

Another way of looking at it is that all the animal species who didn't find at least something tasty to eat have all gone extinct from hunger. --Sean 14:03, 14 January 2008 (UTC)

See how well being delicious has helped lettuce! It’s grown on six continents and is in no danger of dying out. Compare this to all the awful tasting wildflowers that are at the brink of extinction. Same thing with dogs; they’re cute and cuddly so they live everywhere with our help. The gray wolf isn’t quite so lucky. --S.dedalus (talk) 02:21, 15 January 2008 (UTC)

Seems to me this assumes facts not in evidence. Who exactly thinks lettuce is delicious? I mean, romaine and radicchio are OK, I guess, but iceberg is appallingly horrible, and none of them are as good as spinach or arugula or "field greens" in general. --Trovatore (talk) 01:50, 17 January 2008 (UTC)

Iceberg may not be tasty, but it doesn't taste of much. It provides a structural matrix to many salads that tastier lettuce just can't support. Combined with not tasting of much, I find this makes it a perfect choice in certain salads, spacing the tastier ingredients and ensuring even coating with the dressing. Skittle (talk) 17:28, 17 January 2008 (UTC)

Well, de gustibus, dude. To me crunchy, wet, and tasteless equals gross. The thing that's not a matter of taste is that iceberg has essentially zero nutritional value -- at best it takes up room in your stomach, which possibly could keep you from eating worse things, but given that most people slather it with some disgusting sauce, even that's a dubious proposition.

As for me, give me a salad of bitter greens with just a little olive oil, salt, and lime, and possibly some red bell pepper, tomato, and/or very ripe avocado, and I'm good. If I'm feeling extravagant I might throw in some feta or kalamata olives. --Trovatore (talk) 18:31, 17 January 2008 (UTC)

What will happen if...

What will happen if you add a fluid to magma?98.224.10.129 (talk) 01:07, 14 January 2008 (UTC)Brain

What sort of fluid are you thinking of?--TreeSmiler (talk) 01:11, 14 January 2008 (UTC)

The natural fluids in magma, are the magma itself, water, Hydrogen chloride or carbon dioxide and maybe sulfur dioxide. Under pressure, these gasses can become liquids and dissolve in the molten rock. However if a volcano errupts under water, you get pillow lava as themolten rock is instantly frozen. without pressure the liquids will be vapourized. Some other kinds of liquid like petroleum will not be miscible in magma, and will decompose to simpler hydrocarbon gasses and carbon. Graeme Bartlett (talk) 05:59, 14 January 2008 (UTC)

Odd question

One day in my science class, being the smartass that i am i asked my teacher what would happen if hypotheticly you could swallow lava without dieing. well she basicly just ignored me and went on teaching which led me to wonder what would happen to it. Would it harden or would you eventually piss lava out? Also if it would harden could u survive by like having surgry to have your stomach competly cut open? BonesBrigade 02:26, 14 January 2008 (UTC)

Well, do realize that it's a question so absurdly hypothetical that it's nearly impossible to answer with anything remotely approaching "correctness". Obviously, in the real world, if you tried to drink hot lava, you'd burn your mouth and probably your whole head off before a drop of the stuff ever reached your stomach. We have to suspend so much disbelief (or, rather, ignore so many laws of nature) in imagining that you could drink it like any old thick, hot liquid that in that altered reality, there's no telling what would happen next.

My best answer is that you'd end up with a big chunk of solidified rock in your stomach which you could neither digest nor pass, and which would therefore lead to rather severe gastric distress. Or maybe, if you happened to have a relatively full stomach already, when the hot lava hit the rest of the food and liquid in your stomach, it would sputter and solidify in lots of separate little fragments, which you could try to pass (but which would probably only end up causing different kinds of gastric distress further down). —Steve Summit (talk) 02:39, 14 January 2008 (UTC)

(after edit conflict and lava break) Interestingly, your question isn't that odd. See "Would it be physically possible to drink lava?" Your caveat "without dying" makes the question very difficult to imagine. Lava "is a liquid at temperatures from 700 °C to 1,200 °C (1,300 °F to 2,200 °F)". Maybe the question needs to be rephrased for a non-toxic substance with a melting point somewhere between body temperature and very hot coffee. Of the elements, rubidium, white phosphorus, and potassium fit the temperature frame, which leaves us with their toxicity. ---Sluzzelin talk 02:44, 14 January 2008 (UTC)

Those three would mainly leave you with the fact that they would explode if you tried to eat them. Someguy1221 (talk) 02:55, 14 January 2008 (UTC)

Other metals I can think of would be cesium (which would also explode) or gallium. I'm not sure what would happen if you drank gallium. Someguy1221 (talk) 03:01, 14 January 2008 (UTC)

I imagine you could probably swallow very small amounts of lava and survive. I say this because my grandfather was a welder during WWII and once when welding in a small enclosed space inside the hull of a ship, managed to get a pea-sized globule of molten metal catapult into the back of his mouth. Before he could react it slipped down his throat, still as a liquid. He told me he has burns to his throat and a bit of moderate stomach pain for a day or so, but apart from that was fine. He passed the metal - now solid - a few days later. Rockpocket 02:49, 14 January 2008 (UTC)

I'm a bit skeptical of your grandpa's story, specifically the part about it being "still liquid" when he swallowed it. I suspect it cooled enough to solidify during it's flight through the air, but was still hot enough to burn him. After all, how would he know it was liquid when he swallowed it ? The ability to detect the difference between a solid and a liquid would certainly be lost due to the high temperature of the object. StuRat (talk) 13:34, 14 January 2008 (UTC)

I expect he couldn't know for sure it was still liquid when swallowed, however he had been scarred with enough globules of liquid metal that had hit his skin (to which I can testify, even 50 years later, those scars remained) to be familiar with what the state of those globules are. It seems fair to assume that if they hit your skin still liquid, then they would probably hit your throat still liquid. Rockpocket 18:01, 14 January 2008 (UTC)

....AWESOME!!! BonesBrigade 02:58, 14 January 2008 (UTC)

A Google search brought up the statement that crematoriums use temperatures of about 1500 degrees Fahrenheit for several hours. There was also a mention of the fact that soft tissue burns at a much lower temperature than bone though. My guess would be that lave would not instantly sear through your cheeks or whatever. Your muscles would probably be instantly disabled though making swallowing difficult (assuming we’re not talking about the apparently very small sample of molten material in Rockpockets example). Wow, this topic’s very macabre. --S.dedalus (talk) 05:05, 14 January 2008 (UTC)

You'd probably be spending a lot of time in the lavatory. --Sean 14:09, 14 January 2008 (UTC)

You'd be shitting bricks passing rocks for a week ! Astronaut (talk) 03:14, 15 January 2008 (UTC)

Name of medical condition ?

I seem to recall that consuming too much of some mineral causes nodules to form under the skin containing that mineral. However, I forget the mineral and the name of the condition. Does this sound familiar to anyone ? --StuRat (talk) 03:53, 14 January 2008 (UTC)

Agyria is caused by silver deposits under the skin. Gout also sometimes progresses such that tophi grow under the skin. --Mdwyer (talk) 20:17, 14 January 2008 (UTC)

A delicious 9V battery

OK so a 9 volt battery will shock you if you put its terminals on your tongue. So what would happen if you swallowed it whole? Assuming it fell into a position where both terminals were touching your stomach lining, would you feel the shock? Would it damage your tissues? Would the shock last until evacuation? HYENASTE 04:03, 14 January 2008 (UTC)

Amazingly, this seems to be a popular pastime there are many google links. This is just one [3]--TreeSmiler (talk) 04:13, 14 January 2008 (UTC)

A standard 9V battery is a cardboard case with six tiny 1.5V batteries inside of it. Those have a very thin casing that is easily crushed between your fingers. So, the battery will not stand up to stomach acid for very long. I did an experiment with putting one in a glass of water. The battery turned to mush rather quickly. I strongly suggest you try it in a glass of water instead of swallowing it. It is simply stupid to risk your life so you can say you swallowed a battery. -- kainaw™ 04:40, 14 January 2008 (UTC)

Cardboard? I have here a 9V battery. Just as with any other 9V battery I remember handling, the casing feels like metal. If I look at how it's crimped, it looks like metal. And if I scrape off a bit of the paint then my ohmmeter shows that it conducts electricity. So I don't think it's cardboard! The two ends of the battery do seem to be cardboard, though. --Anon, 07:03 UTC, January 14, 2008.

I'm in England. I've looked at three makes of 9v battery, all are certainly metal-cased but the two end pieces seem to be plastic. I doubt they would be cardboard. So not very digestible!! - Adrian Pingstone (talk) 08:35, 14 January 2008 (UTC)

This confusion arises because there are two styles of 9V batteries. The modern style is, indeed, 6 cylindrical alkaline cells (smaller than an AAA cell) wired in series and enclosed in an outer steel container. But an older style of 9V battery was made from six flat, rectangular carbon-zinc cells stacked up to form the series circuit. These older batteries of cells were then coated with wax and wrapped in paper or cardboard.

Atlant (talk) 19:02, 14 January 2008 (UTC)

That makes perfect sense. When I did my "experiment", I was in the Marines. Everything we received was old junk given away from some other military branch. For example, my M16 had a stamp inside the grip marking it as a reject from the Air Force. So, it is no doubt that we had old batteries - or even new ones that were so cheap that they used cardboard instead of plastic. -- kainaw™ 20:22, 14 January 2008 (UTC)

Don't get carried away playing with the battery—see Steve Baker's link to the Darwin Awards. -- Coneslayer (talk) 13:45, 14 January 2008 (UTC)

See also pica. --Milkbreath (talk) 18:57, 14 January 2008 (UTC)

Atlant: even modern Zn-C 9V batteries are made of rectangular cells, at least in the UK, except that the wrapper is now metal and not cardboard. (Example here) --Heron (talk) 19:27, 14 January 2008 (UTC)

What an excellent example of detailed forensic? work by J. Broncks. Now I dont have to do the same!--TreeSmiler (talk) 19:43, 14 January 2008 (UTC)

Body Language

Dear Sir/Ma'am,

Do you know of someone who can clean up the page on body language. I asked one of the moderators of the category but they sent me here. —Preceding unsigned comment added by Dez82 (talk • contribs) 08:26, 14 January 2008 (UTC)

If you haven't already, you could also try the Humanities desk here [4] since this may be a Behavioural science and/or psychology related article. Julia Rossi (talk) 09:22, 14 January 2008 (UTC)

water and fire

OK. possibly a daft question, or more likely one that's asked on a very regular basis. If hydrogen is flamable, and oxygen is fuel to fires, why is water not flamable? How can it be one of the best things for putting out a fire? Also, why is it wet (liquid) when its components are gasses?

thanks 83.104.131.135 (talk) 10:46, 14 January 2008 (UTC)

When you add hydrogen gass and oxygen gass together and add just a little bit of heat you get a big woosh (or a plop depending on who you ask). A lot of energy is released in this reaction. The reason for this huge amount of energy is that water(H2O) is a very stable state for hydrogen and oxygen to be in. Thus water doesn't really feel like reacting with anything else anymore.

Another way of looking at it is that burning is a form of oxydation. But the hydrogen in water has allready been oxydized (by oxygen) thus it won't react any further.

Why is water a liquid and not a gass? well the answer lies in hydrogen bonding. If there was no hydrogen bonding water would be a gass.PvT (talk) 11:20, 14 January 2008 (UTC)

To clarify, hydrogen and oxygen tend to attract each other (see hydrogen bonding). This means that the water molecules will try to stick together as the hydrogen bonds pull them together - this stops the molecules from flying around freely (as happens in a gas). Laïka 12:46, 14 January 2008 (UTC)

thanks everyone for the answers so far. Laika - your explanation of the water/gas thing was very clear - thanks. As to the others, if you're saying that when the oxygen and hydrogen combine, the hydrogen burns. Once this is 'spent' then what's left is water which won't burn because they hydrogen has run out of energy. Does this mean then that (outside of a labortatory perhaps) no new water is created? (in terms of rain/seas whatever) Because there's a distinct lack of explosions when it rains (which, thinking about it, might be fun!) cheers! 83.104.131.135 (talk) 13:05, 14 January 2008 (UTC)

Some water may be created during events like lightning strikes high in the atmosphere where there may be some free hydrogen. Very little water is created per year, but it can add up over billions of years to quite a bit. One theory is that most of the water came from early in the solar system's history, either created on Earth during that violent period or created on meteorites and comets as ice, with these objects later hitting Earth and delivering the water that way.

Also, the use of water to fight fires is because it uses up a lot of heat energy to boil water, thus hopefully cooling the fire down below combustion temperature and putting out the fire. StuRat (talk) 13:26, 14 January 2008 (UTC)

It's not quite true that no new water is being produced - every day, your body makes about 0.4 litres (just under a pint) of water out of fats, sugars and proteins. It's not much on a global scale, but it's enough for many animals (such as many arthropods and desert animals) to survive on - see Fluid balance. Likewise, burning chemicals such as petrol or sugar releases a bit of water as the hydrogen in the fuel reacts with oxygen from the air. This happens because although the hydrogen loses some of its potential energy when it reacts to form the fuel, it still has more energy than it would if it became water. Laïka 16:12, 14 January 2008 (UTC)

Traditional Japanese sitting arrangement

Before martial arts lessons, and while eating in some Japanese and possibly other Asian arrangements, people kneel with one foot slightly overlapping the other. Is this actually sensible or liable to cut off circulation? I also tend to get a cramp in my foot if my toes are bent towards the sole (downwards with respect to the foot as opposed to upwards). If I've oversimplified the posture somewhat, someone more worldly might set the record straight shortly. ----Seans Potato Business 12:41, 14 January 2008 (UTC)

The position is known as seiza. Our article states that among those with little experience of seiza, "maintaining it for more than a minute or two tends to lead to loss of circulation, with the accompanying 'pins and needles' feeling, followed by painful burning sensations, and then eventually complete numbness in the legs. However, the physical discomfort lessens with experience as the circulation of the blood improves". Much like any other unusual posture, repeated practise improves flexibility and circulation. Special cushions are also available which support the legs and buttocks and relieve pressure on the feet, reducing the risk of cramp. Laïka 16:16, 14 January 2008 (UTC)

9V battery on the tongue again...

Yes, we all know it tingles and maybe hurts a little bit - but what's the deal with that foul taste afterwards? --Kurt Shaped Box (talk) 12:44, 14 January 2008 (UTC)

Are the conditions they are made in very sanitory? I would guess it is just the taste of the metal. (Also did you have to go do this to discover this - be honest :) ). I think licking coins produces a similar taste without the electrocution. Lanfear's Bane | t 13:02, 14 January 2008 (UTC)

Didn't *have* to - but there's a lot of things that we don't strictly *have* to do when we're kids... ;) --Kurt Shaped Box (talk) 18:31, 14 January 2008 (UTC)

To be pedantic, it isn't electrocution when it does not result in death. Bovlb (talk) 21:16, 14 January 2008 (UTC)

With the voltage and whatnot, I wouldn't be surprised if some of the metal on the cathode/anode (forget which it would be) is oxidized, so that you could taste the metal ion. From a biological standpoint, I don't think it should be possible to taste neutral metal particles - they have to be charged, so that taste receptor proteins can detect the size and charge density of the ion.18.96.6.248 (talk) 14:04, 14 January 2008 (UTC)

FYI, it's a very similar taste to the one you experience when (purposefully or not) chewing on tinfoil. It's hard to describe - but it's a 'sharp' sort of taste. --Kurt Shaped Box (talk) 18:31, 14 January 2008 (UTC)

There are only five tastes that the human being can distinguish: sweet, sour, salt, bitter and umami. I suspect its not sweet, salt or umami, so that leaves sour or bitter (or a combination of the two). I suspect that the taste is caused by acids or alkalis being produced on the tongue. Now which of these tastes bitter or sour?--TreeSmiler (talk) 19:22, 14 January 2008 (UTC)

Ah Alkali tastes bitter and acid tastes sour. So now you know.--TreeSmiler (talk) 19:27, 14 January 2008 (UTC)

Insect maturbation and animal in general

Some time ago I saw an insect hovering in air for some time and ejecting some fluid after a while. Now seeing as insects should only expel feaces in semi-solid form, I concluded (with the help of the embarassed expression of my biology teacher when I asked her about it) that this insejt was masturbating(please correct me if I'm wrong). I wanted to ask which animals don't mastubate? And why?Bastard Soap (talk) 13:57, 14 January 2008 (UTC)

Our article on Animal sexual behaviour gives examples of similar behaviour in most species of mammal - it doesn't mention insects, but presumably there's nothing to stop them. Laïka 16:26, 14 January 2008 (UTC)

For some reason, I just can't imagine tortoises masturbating... --Kurt Shaped Box (talk) 02:19, 15 January 2008 (UTC)

• I'm no biologist, but why can't insects expel liquid waste? --M@rēino 16:39, 14 January 2008 (UTC)
• And some insects spit, saliva to digest, or nasty chemicals to kill or repell, and some have a sting with liquids to poison, and then some produce liquid silk to make a thread. There are many liquid possibilities. Graeme Bartlett (talk) 19:56, 14 January 2008 (UTC)

Female fish lays unfertilized eggs. Male fish expel sperms to fertilize them. Would you call this masturbation? NYCDA (talk) 22:33, 14 January 2008 (UTC)

No, I’d call it birth control. --S.dedalus (talk) 02:14, 15 January 2008 (UTC)

Yes. Yes I would. I hope that God is watching them too. --Kurt Shaped Box (talk) 02:15, 15 January 2008 (UTC)

The ceiling kitten is definitely watching them. --Dweller (talk) 15:20, 16 January 2008 (UTC)

Electrical question

Some time ago I was replacing an electrical socket and had a scary experience: I turned off the power at the switch box, verified that it was off by 1) hearing a radio that was plugged in go silent when I cut the power, and then 2) testing it with a doodad that lights up when you hold it near a power source, and then 3) by swatting the wires with the back of my finger: all negative. Then when I was wiring the new plug in, I happened to touch both wires with one hand and felt a definite tingling go through my fingers. I wasn't burned, and it scared more than hurt me. What could have caused this small amount of current to be going through the wires? A short circuit somewhere? Inductance? --Sean 14:47, 14 January 2008 (UTC)

It may have been stored charge - perhaps in a capacitor somewhere else in circuit, or even just in the wires; I've had a nasty shock from touching the live and neutral pins of an unplugged blender. Laïka 16:20, 14 January 2008 (UTC)

One possible reason is that some switch boxes only cut off the live wire. If the neutral is not properly earthed, you could still get a shock when touching the neutral wire and earth.--Shantavira|^{feed me} 17:17, 14 January 2008 (UTC)

What country did this happen in? With proper house wiring in good condition, this could not happen in the US. You had a radio plugged in, so that would have bled away any mysterious phantom charge that might have impossibly been there. A length of non-coiled wire will not develop an appreciable induced voltage under any normal conditions; that would take a nuclear strike or a lightning bolt or something. If I were you, I'd make sure I had a good earth ground to the house, anyway. (If you get between the earth and the house, it can kill you if things aren't right, so let an electrician look at it.) Then I would check every connection in the house for good ground and correct wiring, both at the box and at the other end. Something is wrong. --Milkbreath (talk) 17:45, 14 January 2008 (UTC)

In the USA. The house is about 30 years old. I'm not the owner, but I'll let her know. Thanks, all. --Sean 19:15, 14 January 2008 (UTC)

I've seen Americal wiring and it scares me. DuncanHill (talk) 19:28, 14 January 2008 (UTC)

With regard to With proper house wiring in good condition, this could not happen in the US., I'm not so sure about that. There's at least one situation where you might be able to feel something: Imagine a cable that is carrying two different circuits fed from two different breakers. De-energize one circuit and work on it. The circuit is sufficiently isolated from power that there's no hazard, but capacitive coupling within the cable might put voltage (sourced from a high impedance) on the otherwise-open wires. This situation should be pretty rare, though. In the U.S., two circuits sharing a common neutral conductor are supposed to have their supply breakers mechanically-tied together so both are energized and de-energized together, but it's also allowed to have cable with two hots and two neutrals; this rare sort of cable doesn't require mechanical-tying of the supply breakers.

Atlant (talk) 19:42, 14 January 2008 (UTC)

Atlant, I dont think capacitive coupling at 60 Hz has any chance of creating a dangerous voltage unless you are talking miles of cable. No, the answer is clearly given in my earlier post just below: It is Common impedance coupling On which we dont seem to have an article.--TreeSmiler (talk) 21:18, 14 January 2008 (UTC)

Please note that I don't claim that a "dangerous" amount of current is available, only that a "sensible" amount could be present. And I think if you do the math, you'll reach the same conclusion that I did; 26 nF has a capacitive reactance of 100Kohms (that is, approaching dry skin resistance) at 60 Hz and it's not inconceivable that a cable might have capacitances approaching at least a few nF. And thanks to gadgets such as phase-control dimmers, power lines often have noise components at frequencies much higher than 60 Hz, reducing the amount of coupling capacitance needed to allow someone to "sense" something.

Atlant (talk) 14:15, 15 January 2008 (UTC)

Atlant, the capacitance of twin and earth cable used here is 100pF/m. I dont know where you got your figure of 26nF, but that would equate to a wire run of 260m of good old British cable. I know houses tend to be quite big in the US, but this sort of run is, shall we say, quite large. Assuming a more conservative run of, say 26m, this would give a capacitive reactance of about 1Megohm. At 120V rms this obviously gives 120uA rms through the body( neglecting the 700R or so internal resistance of the human being). According to PD6519 Part1:1988 [5] (an IEC/BSI document), body currents below 500uA usually have no reaction effect. Also dont forget that the neutral wire would probably be earthed at the distribution board AND the OP said he had removed the fuse for the circuit in question. Capacitance effects are therefore completely eliminated and the only possibility is that the neutral was elevated and he touched neutral and earth at the same time. However, the neutral would need to be elevated by more than about 50v for him to feel anything I think.--TreeSmiler (talk) 23:25, 15 January 2008 (UTC)

Addendum. After a bit of Goggling it appears that about 1 mA is the threshold sensitivity on the skin [6]--TreeSmiler (talk) 23:43, 15 January 2008 (UTC)

Whatever Google might say, I can detect currents much smaller than 100 microamps, possibly down to 10 microamps in some conditions. In my younger (and more foolish) days I used to experiment with the effects of different currents on skin, flesh and muscle. I don't advise anyone else to repeat my experiments - I didn't use mains voltage for the higher current tests! 3 mA is considered the safe limit anywhere near the heart, but it takes about 10 mA to stop muscles working. dbfirs 09:48, 19 January 2008 (UTC)

It is possible to get a small voltage between neutral and earth because there may be a small voltage drop across two end of a neutral wire passing a large current. This should not amount to more than a few volts and should not be enough to present a shock hazard. If you have received a tangible shock, then you should get the wiring checked out by a qualified electrician. Here lies the danger of DIY electrical work!--TreeSmiler (talk) 19:38, 14 January 2008 (UTC)

You probably felt a slight shock because appliances that were still connected to the line gave a feed back. Generators are motors in reverse. If you had a fan still connected and it was still turning, it would in effect become a generator. Any appliances could also be causing the feed back. Next time you replace a recepticle, connect a incadecent lamp to it. Confirm the light went out and wait a few more minutes for the light to drain the residual charge from the appliances. BTW TreeSmiler I think you mean inductive not impedance coupling. The chances of capacitive or inductive coupling is extremely remote to be case here. NYCDA (talk) 22:23, 14 January 2008 (UTC)

Yeah, that's true. A big fan spinning down would do that. So, it can happen a little. But I still don't like it, and I'd want to verify the cause. --Milkbreath (talk) 00:13, 15 January 2008 (UTC)

This is why utility workers say "It ain't dead til it's grounded." Perhaps somehow the switch killed the neutral instead of the hot phase. That would make the radio go dead but leave jolting voltage between the phase wire and the ground. The neutral to ground voltage is usually not all that high. I would bet that if you had checked it with a voltmeter you would have seen a steady voltage between conductors or between one of the conductors and ground of at least tens of volts. Perhaps there was a problem with grounding. Many power quality problems wind up being such. I doubt is was a motor winding down and acting as a generator. There could be a sneak circuit through another appliance which put some voltage on the phase conductor which you isolated from the mains by opening the breaker. Edison (talk) 03:34, 15 January 2008 (UTC)

Permanent Marker

Strange question but...Is the ink from permanet markers flammible? If I colour in something around a fire-place with permanent marker would it be liable to set on fire? —Preceding unsigned comment added by 194.221.133.226 (talk) 15:32, 14 January 2008 (UTC)

it shouldn't be flammable after having dried...18.96.6.248 (talk) 16:11, 14 January 2008 (UTC)

It depends what the something is. There are usually strict regulations about what materials can be used in a fire surround. Marker pen ink is unlikely to make it worse though (whereas some paints are flammable).--Shantavira|^{feed me} 17:21, 14 January 2008 (UTC)

Feline Breeding

There is a void of information about becoming a cat breeder. For first timers it would be really helpful to have some solid information about the ins and outs of cat breeding. I've gleened some info and put it on my site, Alien Encounter Cattery but I cant find a single source for the intricacies of breeding, genetics, in-breeding and the actual physical labor involved with cat breeding in general. If there is anyone out there who could point me in the right direction and/or provide this info that would be great!

Sara —Preceding unsigned comment added by 63.200.184.126 (talk) 18:14, 14 January 2008 (UTC)

Where have you looked? Amazon, for example, have plenty of books on the subject, including such titles as The Complete Book of Cat Breeding, Breeding Pedigree Cats, Proven Marketing Tips for the Successful Cat Breeder, A Handbook of Pedigree Cat Breeding, Cat Breeding: A Complete Guide, and many more. I wouldn't expect to find much information on such a specialist subject for free on the Internet. It's not as though someone can usefully write just the odd webpage about it. Why would they when it's their livelihood?--Shantavira|^{feed me} 17:22, 15 January 2008 (UTC)

Spice effects

Why do hot spices make people have runny noses and make people feel hot? How and why do hot spices cause those physiological effects in humans? —Lowellian (reply) 18:38, 14 January 2008 (UTC)

• For a start (by no means the complete answer), see Capsaicin. --jpgordon^∇∆∇∆ 18:59, 14 January 2008 (UTC)

Gene synthesis

Is it possible to synthesize an arbitrary DNA sequence? As in, I send a document reading "AACGTACTACGATCGACTACGTGATC..." off to a lab and they return to me a sample of DNA with that sequence. If this is possible, how is it done? --Rannovania (talk) 19:47, 14 January 2008 (UTC)

Yes, you can read about it in Oligonucleotide synthesis. Someguy1221 (talk) 19:54, 14 January 2008 (UTC)

I do it all the time. You can order DNA primers from many biotech vendors. Invitrogen has some info in a FAQ that you might find useful. — Scientizzle 23:14, 14 January 2008 (UTC)

Blood Clot

question removed

The Wikipedia Reference Desk is not able to offer medical advice. Please consult your (or your mom's) physician or seek assistance from appropriate emergency medical services. Dragons flight (talk) 21:58, 14 January 2008 (UTC)

Question and replies re-removed. --Milkbreath (talk) 03:47, 15 January 2008 (UTC)

Diet Coke/Pepsi, ice, and foam

As part of a New Year's resolution to drop a few pounds, I recently switched to drinking only diet sodas (don't worry, I am exercising and have made other dietary-related changes). I couldn't help but notice that Diet Coke and Diet Pepsi seem to create MUCH more foam when added to a glass full of ice than their non-diet cousins. I have to wait much longer for the suds to die down before I can continue pouring very much at all in. Why would this be? I'm just curious. --24.147.69.31 (talk) 23:03, 14 January 2008 (UTC)

I don't have an answer, but I suspect that whatever the reason is, it's related to why the Mythbusters determined that Diet Coke was the ideal choice of drink for the Diet Coke and Mentos experiment. Confusing Manifestation(Say hi!) 01:31, 15 January 2008 (UTC)

Poke you finger into the foam. Works wonders. —Nricardo (talk) 01:44, 15 January 2008 (UTC)

I've been curious about the stability of foam is sodas as well. I've noticed that the foam produced when making an ice cream float with coke is extremely stable. I could leave it for minutes and a lot of it would still be there. I wonder if it has anything to do with the fat content of ice cream making a stable film. (I'm sorry for talking about coke floats in a diet related discussion by the way... :P Perhaps this can be attempted with sugar free ice cream and diet coke?) 152.3.44.183 (talk) 01:54, 16 January 2008 (UTC)

Ripply heat effect

What's the name for the effect when you can see the heat rising over something and it looks all ripply? Bellum et Pax (talk) 23:20, 14 January 2008 (UTC)

The basic physics involved is called refraction. I don't know if there is a name for the ripply effect per se, since that is just atmospheric refraction with turbulence. See also: mirage. Dragons flight (talk) 23:43, 14 January 2008 (UTC)

An astronomer would call it "really bad seeing". -- Coneslayer (talk) 01:31, 15 January 2008 (UTC)

It's called heat haze, but that just redirects to mirage. --Heron (talk) 19:24, 15 January 2008 (UTC)

Schlieren lines? DMacks (talk) 19:43, 15 January 2008 (UTC)

January 15

Big Pupils

My pupils are bigger than most people naturally. Could someone explain why? Hmrox (talk) 00:48, 15 January 2008 (UTC)

You are taking drugs?--TreeSmiler (talk) 02:37, 15 January 2008 (UTC)

For the same reason some people have bigger ears, a bigger nose, bigger breasts or a bigger penis. Genetic diversity coupled with different developmental environments. Its been estimated that genetic factors account for as much as an 80% contribution to eye pupil size diversity, suggesting environmental factors account for the rest. Moreover, if you are a female, you may consider yourself lucky as, all things being equal, you will be more attractive to males than your smaller pupiled friends [7]. See also Wikipedia:Reference desk/Archives/Science/2007 September 29#Pupil size. Rockpocket 02:49, 15 January 2008 (UTC)

Is it possible you're a kewpie doll, or an anime character? :-) —Steve Summit (talk) 02:56, 15 January 2008 (UTC)

You teach high school seniors? They are larger than most other pupils. Edison (talk) 03:28, 15 January 2008 (UTC)

Hehehehehehe! Entirely excellent & evocative edit Edison! hydnjo talk 08:47, 15 January 2008 (UTC)

Yep,I`ve got another Physics Magazine Question For You

According,to Physics Weekly I have to get the playing card on top of the pennies,from the embriodery hoop into the graduated cylinder. Also,before that It says three beakers and a tray of toilet paper rolls on tio of those the eggs.You,whack the tray with the broom.The eggs,went into the beaker.I need to draw a demo,there`s a 50,00 dollar prize if I win so it`s really important,that I win so hurry up.Basicilly,I need to know which is the best procedure. —Preceding unsigned comment added by 68.161.128.203 (talk) 02:06, 15 January 2008 (UTC)

Is anyone else utterly disgusted by this question?18.96.7.74 (talk) 02:14, 15 January 2008 (UTC)

Haha, yeah, you don't get much help when you advertise that it's for a cash prize that you want to win, even though you're not willing to put in any effort. That's worse than homework! --24.147.69.31 (talk) 02:29, 15 January 2008 (UTC)

Please, think about the questions in Physics Weekly rather than ask for the answers here. it will do your brain far more good.--TreeSmiler (talk) 02:36, 15 January 2008 (UTC)

A point of clarification: are you, in fact, a troll? That is, do you really expect people to do your work for you (and in a hurry, to boot), or do you just enjoy seeing us get riled up at the breathtaking impertinence of your questions? —Steve Summit (talk) 03:06, 15 January 2008 (UTC)

I can't even find a Physics Weekly magazine. Bellum et Pax (talk) 03:20, 15 January 2008 (UTC)

I had assumed it was foreign, given the poster's non-standard punctuation (using ` instead of ' as an apostrophe, using , as the dollar separator) and dodgy spelling and grammar, but the IP address is from the US, so who knows. --24.147.69.31 (talk) 03:32, 15 January 2008 (UTC)

Well perhaps English just isn't his native language. The punctuation is definitely his? style, see Wikipedia:Reference desk/Archives/Science/2007 December 16#This Is Not A Homework Question and Wikipedia:Reference desk/Archives/Science/2007 December 17#I`ve got a question about a sombero. In any case, I guess we're looking for a monthly publication that comes to the U.S. around the middle of the month Nil Einne (talk) 17:58, 16 January 2008 (UTC)

May I just mail you the $50 rather than doing the work for you so you win it? Edison (talk) 03:27, 15 January 2008 (UTC)

Seeing as he used this IP address to vandalize an article directly before asking this question, I feel it is safe to assume that the question is nothing more than trolling. -- kainaw™ 03:48, 15 January 2008 (UTC)

I'm not so sure, his? last physics weekly question was about the same time last month suggesting to me this is really coming from some magazine. Nil Einne (talk) 18:12, 16 January 2008 (UTC)

..."it`s really important,that I win so hurry up..." We're hurrying sir 68.161..., we really are! ;-)) Meantime you may want to go and do some more vandalizing at Tigers! hydnjo talk 08:38, 15 January 2008 (UTC)

Oh, I am *so* tempted to put something that will make him break the eggs all over the floor... :-) 63.3.19.1 (talk) 01:53, 16 January 2008 (UTC)

He's also migrated over to the Math Desk if you are curious. --24.147.69.31 (talk) 15:48, 16 January 2008 (UTC)

Are we all "free floating brains in space?"

Allan Guth, a cosmologist at MIT, reportedly says [8] that there should be "an infinite number of free-floating brains in space" without even a skull, a body, a space suit or a habitable planet, for every normal brain. How does this make sense? Edison (talk) 04:15, 15 January 2008 (UTC)

Skimming the article briefly, it looks like a combination of two ideas:

1. The proposition, long discussed by SF authors and late-night armchair philosophers alike, that we can't really tell the difference between the real world it seems we exist in, versus an isolated brain which is just imagining it all. [P.S. I figured we probably had an article on it, which Someguy1221 has kindly provided a link to. 04:44, 15 January 2008 (UTC)]
2. The physicist's maxim: "That which is not prohibited is mandatory". Personally, I favor the recasting by Douglas Adams: "In an infinitely large Universe, such as, for instance, the one in which we live, most things one could possibly imagine, and a lot of things one would rather not, grow somewhere." —Steve Summit (talk) 04:26, 15 January 2008 (UTC)

It seems to me you have to assume that life is possible for only a truly infinitesimal span of time with respect to the life of the universe. Since we don't know the ultimate fate of the universe, and we don't know what came "before" (can I say before? Time might not have existed...) As such, this is just another answer, however amusing, to that annoying question. Someguy1221 (talk) 04:36, 15 January 2008 (UTC)

Brains? In space? I think not. If a brain was to be left floating in space, it would quickly freeze, the biological processes that keep it alive would not be able to work, and it would die. Be rest assured your brain is probably nice and warm inside your skull. Astronaut (talk) 15:18, 15 January 2008 (UTC)

Come to think of it, if Allan Guth was correct, wouldn't someone have noticed by now? Surely some of the infinite number of brains whould have impacted a space shuttle and NASA would need to employ people to wash off the mashed brain goo after every mission. Astronaut (talk) 15:23, 15 January 2008 (UTC)

Not necessarily. As was pointed out last time this came up (I'm too tired to trawl the archive), you only have infinitely many brains in infinite space. It's not clear how many of these brains we should expect to find in the (finite) observable universe, for example. Could be ~1. Algebraist 17:06, 15 January 2008 (UTC)

Of course that observable universe is merely a figment of my imagination, so it stands to reason there is only one brain. Dragons flight (talk) 18:31, 15 January 2008 (UTC)

We have an article about this problem, which is distinct from the brain-in-a-vat problem: Boltzmann brain. --Allen (talk) 21:27, 15 January 2008 (UTC)

The problem ceases to be distinct from the brain-in-a-vat problem when a theorist suggests (as in the OP's link) that we are those brains. Someguy1221 (talk) 21:45, 15 January 2008 (UTC)

Couple points:

• Nobody (except maybe some overimaginative journalist) is claiming the "floating brains in space" are literally brains floating in space. They're just some (hypothetical) "thinking" entities, complex enough to notice that the universe (with them in it) is thermodynamically interesting, but less complicated than the world as we know it (i.e. with all its animals and plants and transistor radios and Britney Spears and global warming and Bertie Bott's Every Flavour Beans -- which, as a side note, I think it's absolutely marvelous that plain old Muggles like us can actually buy in stores).
• Even Alan Guth doesn't believe he's correct. As I read the article, he and every other sane cosmologist are madly trying to disprove the "brains in space" theory. Trouble is, the result keeps falling out of their other theories, whether they like it or not. —Steve Summit (talk) 03:51, 17 January 2008 (UTC)

Well, no, they don't have to be human brains physically, but they do have to be human brains functionally, don't they? That's how, as Someguy is pointing out, you get the "we probably are these brains" aspect of the problem, an aspect that seems to be coming from Guth, not Overbye (the journalist). If they're just thinking entities in comparatively simple worlds, where's the freakiness? They'd just be more friendly neighbors. --Allen (talk) 04:34, 17 January 2008 (UTC)

Concussion?

This question has been removed. Per the reference desk guidelines, the reference desk is not an appropriate place to request medical, legal or other professional advice, including any kind of medical diagnosis, prognosis, or treatment recommendations. If you have injured yourself at work, you should seek any appropriate medical attention, and report your injury to your manager. Unfortunately, random individuals on the internet aren't able to properly examine you or assess your condition; you should take any questions about your health to your doctor. TenOfAllTrades(talk) 16:15, 15 January 2008 (UTC)

Which is what we said! DuncanHill (talk) 16:20, 15 January 2008 (UTC)

Stochastic Resonance

Hi. Is there anyone that could explain stochastic resonance to me in simpler terms than that of the article, if possible? I'm somewhat less interested in fully understanding all the technical aspects of what causes it (I read the article and related links, but don't have a heavy science background), but as it seems like a very interesting, non-intuitive idea I'd like to understand it a little better. Some more examples of specific systems or conditions in which it might occur would be cool if anyone knows of any. Thanks in advance. Azi Like a Fox (talk) 05:36, 15 January 2008 (UTC)

To be as simplistic as possible, you take a system that seems random - such as the number of accidents on I-95 each day. Then, you find a weak, but repeating, increase and decrease pattern. Using that, you predict slight increases and decreases over time. For example, accidents increase on I-95 between Thanksgiving and New Years each year. It is likely that the day with the most accidents won't fall on that time period, but the median number of accidents during the "high accident" time will be higher than the median number of accidents during the "low accident" time. As such, you've pulled a stochastic resonance out of a statistic that appears otherwise to be completely random. -- kainaw™ 11:46, 15 January 2008 (UTC)

I'm not sure that explanation goes far enough, Kainaw — it doesn't say why certain amounts of noise are relevant. Let me try to extend it: consider that on a lonely, country road, there will probably be many days with no accidents at all and a few days with one accident (and ever fewer with more; we'll ignore these). That is, the bad days (1 accident) are much worse than the good days (0 accidents), and there are no in-betweens. Now consider a hypothetical superduperhighway with 500 long, well-utilized lanes of traffic: there will be many accidents a day, and the variation between good days and bad days might be as little as, say, 20400–20600 accidents (which isn't a big difference given the total). Now suppose that the state law is such that on each of these roads (and many more with more moderate amounts of traffic) the police must assign an additional patrol car on the day following any day with a "high" number of accidents (this is 1 for the country road, and, say, 20650 on the huge road). Finally, consider the seasonal variation of the occurrence of these extra police, given Kainaw's model where more accidents occur at the end of the year. Certainly the extra police will be required more frequently when there are more accidents, but if you try to analyze that occurrence, you'll have difficulty in each of the cases I describe. On the country road, because all it takes is one accident to trigger the patrol, there will be scattered extra patrols throughout the year, and they'll never be regular enough that you can (easily) notice that more of them happen at the end of the year. On the busy highway, the number of accidents is so smooth that the 20650 will almost never be hit — even with the increased traffic — and so again you won't be able to detect the increase at the end of the year. But on some street in the middle, which gets 30-40 accidents with a trigger at 41, there will be significantly more "41" days at the end of the year than there are at other times, and there will be enough of them to discern the pattern.

The extra police represent a detector that isn't triggered by the signal alone because it's set too high (above the usual number of accidents). The different roads represent different amounts of (random) noise on the same signal (the holidays' traffic). The country road is all noise, because you can only distinguish 1 and 0; the noise is so much bigger than the signal that you can't see the signal in the result. The huge road is very little noise, because there are so many accidents that they "average out"; adding it to the signal doesn't help the signal ever get above the threshold. The middle-sized road has enough noise to make the signal detectable on occasion, but not so much to trigger the detector at many random times without the signal's help, and so together the signal and the moderate amount of noise produce a clearer resulting signal (where you count the patrols) than you get with the same signal and either more or less noise. The sensitivity of the outcome to the amount of noise, with one particular amount of noise being optimal, is the source of the name "resonance". --Tardis (talk) 20:15, 16 January 2008 (UTC)

Was definitely interested in the signal to noise aspect and how a certain level of noise could actually make the signal to noise ratio better than either less or more noise. Good explanation, thanks a lot. Azi Like a Fox (talk) 10:24, 17 January 2008 (UTC)

Tea, caffeine and health

Slightly odd question: is there a maximum number of cups of tea one should drink in a day in order to avoid dangerous levels of caffeine? Thanks.--Porcupine (prickle me! · contribs · status) 09:32, 15 January 2008 (UTC)

Mine! Follow up to that link - I drink 7-8 cups daily, and I am alive and healthy. Cheers, Ouro (blah blah) 09:47, 15 January 2008 (UTC)

Great - thanks for that!--Porcupine (prickle me! · contribs · status) 09:55, 15 January 2008 (UTC)

No prob. One who loves and respects tea is probably a good person. --Ouro (blah blah) 12:34, 15 January 2008 (UTC)

Not everyone who loves tea is a good person.[9] --M@rēino 23:37, 15 January 2008 (UTC)

Okay, I take that back. --Ouro (blah blah) 07:30, 16 January 2008 (UTC)

I bet he didn't drink proper British workman's tea, well brewed & with full cream milk and sugar, probably some namby-pamby foreign herbal "tea" muck made with lukewarm water. DuncanHill (talk) 07:34, 16 January 2008 (UTC)

I prefer Earl Grey tea, though my favourite brand is German, Messmer. --Ouro (blah blah) 10:07, 16 January 2008 (UTC)

Perhaps I'm wrong but aren't 'namby-pamby foreign herbal "tea"'s a fairly recent phenomon in the west? Nil Einne (talk) 17:35, 16 January 2008 (UTC)

Isnt this a medical question? If not, why not? If so it should be removed per RD guidelines.--TreeSmiler (talk) 00:36, 16 January 2008 (UTC)

I drink ten or more cups a day, and have never died. DuncanHill (talk) 00:38, 16 January 2008 (UTC)

Yet!--TreeSmiler (talk) 00:41, 16 January 2008 (UTC)

It has a 100% fatality rate :) 79.66.24.40 (talk) 02:13, 16 January 2008 (UTC)

As do carrots, apples, and motorbikes, incidentally :) --Ouro (blah blah) 07:29, 16 January 2008 (UTC)

Oil spills

Does anyone know how to remove oil from a cup of sand mix with cooking/crude oil —Preceding unsigned comment added by 58.182.211.238 (talk) 10:57, 15 January 2008 (UTC)

Heat gets some. Heat and a degreasing agent (e.g. acetone) would get almost all. Water based attempts won't do well--BozMo talk 11:20, 15 January 2008 (UTC)

Consider the Surfactant and Detergent articles. --Mdwyer (talk) 18:30, 15 January 2008 (UTC)

It would be hardly worth doing, just get a new cup of clean sand, and buy a new bottle of cooking oil. The natural environment will have bacteria that can metabolize the oil from the sand when it is exposed to ground water and air. If you wanted to recover all the oil to use again extracting it would need some solvent like liquid carbon dioxide that you can totally evaporate without tainting the oil! Graeme Bartlett (talk) 20:08, 15 January 2008 (UTC)

I assumed it was a homework problem. —Steve Summit (talk) 21:14, 15 January 2008 (UTC)

If there are lots of oil, you might try simple filtering first. Then wash the remaining mixer in a bucket of hot water. Remove the sand. Use any technique to remove the oil and water (scooping). You should be left with original amounts of sand and oil once the water is removed. NYCDA (talk) 23:26, 15 January 2008 (UTC)

Your method would also depend on whether you prioritise getting clean sand, or getting clean oil. If, at the end, you want some nice clean sand, and don't care what happens to the oil, then you can follow some of the procedures described above. On the other hand, if you're keen on getting pure oil, free of sand, you might want a more physically-based method, such as filtration. On the hypothetical third hand, your final aim might be getting a jar of sand, and a jar of oil, both relatively free of impurities, and without losing too much of either, which is going to take a slightly more involved method. Confusing Manifestation(Say hi!) 05:48, 16 January 2008 (UTC)

You may want to read about tar sands. There's a section on the extraction process. — Daniel 01:39, 17 January 2008 (UTC)

Grief

Is there a name for the human ability to remain emotionally unaffected by the deaths of thousands of strangers, and yet to be so strongly affected by the death of a loved one? --Bmk (talk) 17:08, 15 January 2008 (UTC)

:Dehumanization has been taught in my psychology course to answer the question 'why do normal people comit horrific acts such as genocide?'. If a person belives another person to be unhuman or a subspecies then it is easier to remove guilt from murdering them. The Nazi government used propganda very effctively to dehumanize the Jews describing them as 'rats' or 'vermin'. The holocaust was implemented by a man called Adolph Eichman, at his trial it was commented on how normal he seemed, to quote Hannah Ardent's book The Banality of Evil: "It would have been comforting indeed to believe Eichman was a monster...The trouble with Eichman was so many were like him and that many were neither perverted or sadistic, that they were, and still are terrifyingly normal." This suggests he led a fairly normal family life and loved those close to him, but was able to permit mass murder by detatching himself from the murder of humans by convincing himself it was not the murder of humans at all, but subhumans. The Rwandan genocide is another exmaple of genocide incited by dehumanization propoganda. With the ruling party using radio to create a negative stereotype of the Tutsi tribe as 'child-eating cannibals'.I hope this makes sense :S. RobertsZ (talk) 17:44, 15 January 2008 (UTC)

I think you answered a different question. The OP isn't suggesting these thousands of deaths were caused by the one who is not suffering; I believe he is referring to the way a normal person doesn't break down in tears whenever he reads the newspaper. Someguy1221 (talk) 18:12, 15 January 2008 (UTC)

Sorry for missenterpreting your question and taking it off track BMK, I would strike it out, but dont know how to... sorry againRobertsZ (talk) 18:22, 15 January 2008 (UTC)

That's ok - it was an interesting answer anyways. --Bmk (talk) 18:35, 15 January 2008 (UTC)

Strike-out is with html: <s>foo</s> makes foo. It's also the 13th button above the edit box. Algebraist 19:44, 15 January 2008 (UTC)

Thanks, I really should try using the sandbox at somepoint trying all this out, RobertsZ (talk) 20:11, 15 January 2008 (UTC)

Sanity? Honestly I mean if people treat the death of complete strangers the same as they did loved ones they'd be driven insane with despair and grief. As they said in the film Swordfish (film) "thousand die every day for no reason at all, where's your bleeding heart for them?" - if they've not taken this from somewhere this statement is far 'deeper' than the rest of this movie... (To put that statement in context here's the lines preceeding...

Stanley: How can you justify all this?
Gabriel: You're not looking at the big picture Stan. Here's a scenario. You have the power to cure all the world's diseases but the price for this is that you must kill a single innocent child, could you kill that child Stanley?
Stanley: No.
Gabriel: You disappoint me, it's the greatest good.
Stanley: Well how about 10 innocents?
Gabriel: Now you're gettin' it, how about a hundred - how about a THOUSAND? Not to save the world but to preserve our way of life.
Stanley: No man has the right to make that decision; you're no different from any other terrorist.
Gabriel: No, you're wrong Stanley. Thousands die every day for no reason at all, where's your bleeding heart for them? You give your twenty dollars to Greenpeace every year thinking you're changing the world? What countries will harbor terrorists when they realize the consequences of what I'll do? Did you know that I can buy nuclear warheads in Minsk for forty million each? Hell, I'd buy half a dozen and even get a discount!

ny156uk (talk) 00:35, 16 January 2008 (UTC)

Might as well quote the famous bit attributed (probably incorrectly) to Stalin: "The death of one man is a tragedy, the death of millions is a statistic." Anyway, from a psychological point of view it probably has to do with the idea of kinship—you care more about those in your "family" (which does not necessarily have anything to do with actual blood relations) than you do out of your family. All sorts of dynamics result from this simple fact (racism probably has a similar mechanism behind it). -24.147.69.31 (talk) 02:12, 16 January 2008 (UTC)

10x Loupe Eyepeice

I have a 10x Loupe eyepiece which I am using to make a simple Refracting telescope. How can I calculate the focal length of this eyepiece? Thanks, 86.154.247.108 (talk) 21:43, 15 January 2008 (UTC)

If you have enough information, you could use the lensmaker's equation. If not, you can shine a pair of laser beams (or a planar beam if you have a nice optics lab available) parallel into the lens and see where they converge. For a lowtech measurement, if the lens is thin enough, place a lit candle on one side of the lens, with the lens level with and pointing at the flame. Hold a piece of paper on the other side and see where the light cast through the lens is brightest. Using the distance to the candle as your "object" distance, and the distance to the brightest casting as your "image" distance, you can compute the focal length with the equation found in the previous link. But note this is not the most accurate experiment, and the equation itself is an approximation. Someguy1221 (talk) 21:53, 15 January 2008 (UTC)

Could you ask an optician? They have some cool gadgets for measuring focal lengths. Julia Rossi (talk) 07:21, 16 January 2008 (UTC)

Looking for a study or news article relating to nightmares

I saw something in the news online within the past two months (probably less) that said something along the lines of nightmares and other dreams possibly being the brain's way of doing disaster preparedness, giving the brain training on how to deal with emergencies. I don't know what the scientific origins were, but one of the comments by researchers was wondering how it would help seeing as so many of our dreams we don't remember. Any help would be great!!! —Preceding unsigned comment added by 154.5.108.184 (talk) 22:27, 15 January 2008 (UTC)

Have you seen the article Nightmare – don't know if it's strictly relevant to your question, but there's a ref source linked to this statement "A recently proposed treatment consists of imagery rehearsal.[1] This approach appears to reduce the effects of nightmares and other symptoms in acute stress disorder and post-traumatic stress disorder.[2]". And more, although it looks more like the other way around: helping people to deal with traumatic experiences and so reduce nightmares, but, over to you. Julia Rossi (talk) 07:44, 16 January 2008 (UTC)

Thanks very much for looking, Julie, but that's not really what I was looking for. Very interesting, but kind of the mirror image of the article I saw. Cheers though. —Preceding unsigned comment added by 154.5.108.184 (talk) 01:04, 17 January 2008 (UTC)

Point taken. Tried lucid dreaming and brain training but no specific article that'd help you so far. Do you remember the publisher of the article? Another link is a pdf here?download=Stress%20report%204.2.pdf that talks about applied neurofeedback training the brain to deal with stress – but to your query re brain having its own preparedness faculty through nightmares, as yet nothing. Zzzzz Julia Rossi (talk) 08:28, 17 January 2008 (UTC)

January 16

Simple decomposition question

When dilute hydrogen peroxide is placed inside a test tube and NaOH and fresh cow liver is added to it to speed up its rate of decomposition, is the NaOH considered an enzyme? The liver for sure is an enzyme, but is the NaOH considered one as well? Acceptable (talk) 00:18, 16 January 2008 (UTC)

An enzyme is a protein that catalyzes a reaction. Since NaOH is not a protein, it cannot be an enzyme. On the other hand, it would be called a catalyst, which is a more general term.

Although the liver obviously contains catalase, can someone else tell me what the function of the hydroxide would be?.. I'm thinking that would just denature the catalase.18.96.5.239 (talk) 00:49, 16 January 2008 (UTC)

Catalase functions optimally in a basic solution. I wouldn't call this a catalytic effect, just a pH effect. Someguy1221 (talk) 03:54, 16 January 2008 (UTC)

Water density fluctuations?!?

Hi. Recently I did an experiment in a group. We poured water into a graduated cylinder (it was supposed to be 10ml at a time but we messed up). We discovered that although the mass of the water went up, it jumped back down then kept going back up. What's with the anomaly? Why was the density always under 1 g/cm³? I think we used tap water. Why the anomaly? Can you tell by the graph? Is it experimental design flaw? Did we mess up on something? Was it an alien invasion? We measured the mass of the cylinder prior to the experiment, then subtracted it to find the actual liquid mass. What's going on? Here's the image. Sorry about the messiness. Thanks.

File:Experimental Water Anomaly.jpg

The graph

~AH1^(TCU) 00:41, 16 January 2008 (UTC)

Mass cannot change like that. Looks like very poor experimental technique to me (probably errors in the weighing)--TreeSmiler (talk) 00:46, 16 January 2008 (UTC)

If you were putting the tared graduated cylinder on the scale and letting it sit there, air currents can easily cause the mass to fluctuate. This is why more precise, analytical balances have glass walls around, to prevent mass fluctuations due to air currents. I have no idea what would cause the mass to be off by that much, though. Maybe you were hovering around the balance and touched it in some way. Or maybe the balance itself is broken. (Did the entire class use a single balance, and did other people have the same troubles?)18.96.5.239 (talk) 00:49, 16 January 2008 (UTC)

(edit conflict)Hi. Well, we used a balancing scale. We had to shift the 100g block first, then the 10g block, then the smaller block that can be shifted at intervals as small as 0.1g. If you want to know what happened between approximately 36g and 50g, at first I used a small 10ml cup for measuring, but it wasn't accurate because by the time I had 5 x 10g, it barely exceeded 40ml on the cylinder. So, I added more water, but it spilt. We cleaned it off, then put the cylinder back on, then I filled the cylinder until the bottom of the meniscus was at about 50ml. I don't think it is the error in the first half of the slope, because that was actually close to the expected result, and I don't think it was in the second half, because the slope continued without any other abberant data. Is the density of tap water different from distilled water? Where do you think we messed up? It did take about a whole minute to adjust the scale so it would give us a reading. Oh, and this question in particular is not homework. Also, I hope you don't mind that I simply changed the destination filename to jpg whereas it was previously bmp. Thanks. ~AH1^(TCU) 00:57, 16 January 2008 (UTC)

Maybe heres some of the things your experiment was designed to show. [10] —Preceding unsigned comment added by TreeSmiler (talk • contribs) 00:58, 16 January 2008 (UTC)

(edit conflict)Hi. Well, even if I did touch it, the babance would simply swerve, then we might have to readjust the micro wieght. The first balance we tried was broken, all the data was used with the second balance. We all used different balances and I don't think they had much trouble unless they forgot to subtract the mass of teh cylinder. Thanks. ~AH1^(TCU) 01:01, 16 January 2008 (UTC)

Well, the page says stuff about temperature, ice, pressure, etc. The temperature was pretty much constant, there was no ice, and if anything adding more water should increase its pressure/density, not lower it, so I don't see how that page explains this huge anomaly. Thanks. ~AH1^(TCU) 01:06, 16 January 2008 (UTC)

From the shape of the graph, I'd say that the most likely cause is the zero point of the balance shifting. --Carnildo (talk) 01:22, 16 January 2008 (UTC)

Hi. By the zero point do you mean the mark that says "0" on the side of the scale, that lines up with the end of the balance opposite the round plate where you place the object to be weighed, that looks like an elongated axe? Well, the "axe-like" part can shift, but to change its position from too high to too low from the 0 mark would only take a shift of several grams on the micro weight. Or, do you mean something in the system shifting? Where should this be and how can it happen? Does something fall off? Thanks. ~AH1^(TCU) 01:30, 16 January 2008 (UTC)

Most measuring devices have a way of adjusting the readout so that they read "0" somewhere other than when it isn't measuring anything. For example, the balance you're using might have a small weight that can be moved back and forth. If that was shifted between when you made the 35ml measurement and when you made the 50ml measurement, the result could be the jump in the graph. --Carnildo (talk) 23:13, 16 January 2008 (UTC)

Towel snapping, water, and pain

Someone told me that when people snap towels at each other, as kids - and probably adults - do at tiems in locker rooms, it stings more when the skin hit is wet. I think that makes sense, but why? I'm guessing water, being a condutor of electricity, might also be a good conductor for pain neurons, and thus the sting lasts longer? Also, why does one's skin get red when this happens - this seems pretty easy to me, the breaking of those tiny capillaries, right?63.3.19.1 (talk) 01:59, 16 January 2008 (UTC)

It doesn't have anything to do with conductivity of pain neurons; the neurons themselves are well below the skin and do not get wet when the skin is wet. --24.147.69.31 (talk) 02:02, 16 January 2008 (UTC)

It seems far more likely that the wetness of the towel is what matters, as that's what gives the towel tip sufficient mass to make a meaningful impact. — Lomn 07:18, 16 January 2008 (UTC)

It also makes the towel more... solid I guess. Compare how a wet towl feels to touch compared to a dry towlTheGreatZorko (talk) 14:18, 16 January 2008 (UTC)

I don't think it's only the wetness of the towel that counts. If you hit someone's unclothed back with your palm (not a towel), it hurts much more if his or her back is wet. – b_jonas 17:29, 17 January 2008 (UTC)

Energy determination

I'm trying to measure the BTU capacity of various torches and soldering irons, etc. both gas and electric according to the standard of 1 degree Fahrenheit temperature increase per pound of water. Is there a formula that I can use instead based on the total reduction in lbs of liquid water after I have applied heat? In other words if I have 2 lbs of liquid water and heat it with a candle until the candle is consumed determine the energy in the candle by simple measuring how much water the candle has evaporated? —Preceding unsigned comment added by 71.100.12.59 (talk) 04:39, 16 January 2008 (UTC)

Not reliably. Different experimental setups will have varying rates of evaporation (surface area affects this), which is enough to invalidate the attempt. Worse, though, is that a setup like you describe doesn't constrain the candle's energy to the water -- heat is free to radiate in all directions, most of which don't result in any measurement on your part. — Lomn 07:23, 16 January 2008 (UTC)

You would get a more accurate result if, instead of trying to evaporate the water, you just heated it inside a container. Then you could measure the temperature rise of the water and estimate the energy it had absorbed. This is the basis of the bomb calorimeter; and don't worry, it's not as dangerous as it sounds. --Heron (talk) 20:51, 16 January 2008 (UTC)

'Company doctor'

If someone is or may be infected as a result of research activities of a co-inhabitant, should they see the "company doctor" of their research establishment or a regular doctor? I'm trying to understand the idea of a "company doctor". ----Seans Potato Business 11:42, 16 January 2008 (UTC)

Did you have a school nurse when you went to school? Same idea. Some companies find it cheaper to put a doctor on retainer - even having the doctor show up at an office inside the company building - rather than throwing money at insurance and having employees take time off work to spend half the day waiting to see some other doctor. There are opinions that a company doctor is a good thing. There are opinions that a company doctor is a bad thing. -- kainaw™ 13:28, 16 January 2008 (UTC)

Also, is the core of your question simply "what is a company doctor?" or is it the opening sentence about "should you opt for the company doctor if your buddy's research turns you into the Hulk?" Those are two very different questions, after all. As for the latter, it's likely that employees have considerable rights in the event of such an occurrence. OSHA would be one place to check that sort of stuff (for those in the US, or, apparently, the EU. Who knew?), and the company's HR department should be well-versed in the particulars. — Lomn 13:53, 16 January 2008 (UTC)

The company's HR department (whatever happened to personnel?) will have a view, but you may find it worthwile to speak to your union rep too. DuncanHill (talk) 14:01, 16 January 2008 (UTC)

An onsite physician may be better-versed in the hazards of your particular workplace and may also be able to see you on shorter notice (and in a more convenient time and place) than an offsite doctor. On the flip side of the issue, a company doctor may face conflict-of-interest issues in dealing with or reporting workplace injuries and mishaps, and may or may not have the resources of a larger clinic or hospital.

In all cases, you should seek the advice of a physician with whom you feel comfortable. If you are concerned about a health and safety issue at work (particularly one related to (mis)handling of infectious materials) there are likely to be statutory requirements for you to report the issue to a manager or company biosafety officer. If you are in a unionized workplace, your union rep would be a good person to speak to, as well. Your human resources department may become involved.

If you suspect (or know) that you have been injured or infected through the negligence of another person in your workplace, keep meticulous records (with a copy stored offsite) of everything that you know (or believe) has happened, and of every document you send or receive. Such records may be invaluable for internal or external investigation of the problem, or during a civil or criminal trial. If you feel the need for specific legal advice, you should ask a lawyer who has experience in employment law. TenOfAllTrades(talk) 15:40, 16 January 2008 (UTC)

a company doctor may face conflict-of-interest issues in dealing with or reporting workplace injuries and mishaps. Too right. I knew someone who broke their arm at my place-of-work-at-the-time, and all the company doctor did was ensure they signed some forms indicating they wouldn't sue and it wasn't the company's fault, before calling an ambulance. 79.66.24.40 (talk) 16:45, 17 January 2008 (UTC)

ARUN S BAGH QUES ABOUT PLUTO

why is pluto exactly called 134340? —Preceding unsigned comment added by 59.95.176.209 (talk) 14:17, 16 January 2008 (UTC)

See Astronomical naming conventions#Minor planets and Pluto#IAU decision to reclassify Pluto. The latter states "If Pluto had been given a minor planet name upon its discovery, the number would have been a little over a thousand rather than over 100,000." - Dammit (talk) 14:51, 16 January 2008 (UTC)

In other words, they looked deep within Pluto's soul, and assigned it a number based on the order in which it joined. -- Coneslayer (talk) 15:11, 16 January 2008 (UTC)

"It comes after 134339, hon." --Anon, 00:37 UTC, January 17, 2008.

Pluto's discovery date (February 18, 1930) falls between the discovery dates of 1163 Saga (January 20, 1930) and 1164 Kobolda (March 19, 1930) - so a sequential number based on discovery date would have to be something like "1163a", or maybe "1163 ½". Looking at List of asteroids/134001–135000, the objects either side of 134340 Pluto are the unnamed objects 134339 discovered on October 16, 1977 and 134341 discovered on June 25, 1979 - but I believe a sequence number is only assigned once an object's exact orbit is determined, which may be some time after discovery. Gandalf61 (talk) 14:29, 17 January 2008 (UTC)

Oh, that is interesting. I assumed that the number was simply the next one available after the supposed demotion of Pluto. Instead it turns out to be a number from exactly the time when Charon was discovered, which led to the computation of Pluto's mass, which was the motive for the event. Did someone actually assign then number 134340 back then, and wait almost 30 years for their evil views to receive official acceptance? (Just remember, all you people who go around editing articles to change planet to dwarf planet ... your planet could be be next, and then who will be left to speak for you?) --Anonymous Pluto partisan, 18:35 UTC, January 17.

Most Toxic

What is the most deadly toxin or poison in the world? By most deadly I mean can kill with the least amount. DTWATKINS (talk) 14:45, 16 January 2008 (UTC)

I think this has come up before. You'll find a useful discussion in Wikipedia:Reference desk/Archives/Miscellaneous/2007 October 16#Most toxic toxin. Cheers! TenOfAllTrades(talk) 15:23, 16 January 2008 (UTC)

Depending on the level of pedantry, oxygen gas kills with a concentration of zero. You might be interested in LD₅₀ and related articles, or you could check the archives for the many many times this has been asked before. TenOfAllTrades cites one of the recent ones above. — Lomn 15:25, 16 January 2008 (UTC)

You didn't specify the time which may pass between ingestion and death. In experiments with rats, mice etc. it's commonly 48 hours. Really short-lived radionuclides would kill in smaller amounts than botulinum toxin, e.g. francium-210 (from my answer to the old question and a table of nuclides I conclude that the LD-50 within 48 hours should be maybe 30 pg/kg, but this comes with a large uncertainty), but they're hard to synthesize in larger amounts and you'll have to be fast to try them before they decay... Icek (talk) 15:30, 16 January 2008 (UTC)

Plutonium is often refered to as the most toxic substance known to man. Whether this is the case or not is debatable. There is a pretty good discussion about toxicity in that article on Plutonium. -- Saukkomies 10:49, 16 January 2008 (UTC)

Um, it's not really that debatable. It's not the most toxic under any reasonable definition. It's toxic, for sure, and can cause major health problems if inhaled, but it's not a good choice to poison someone with, which is a sure sign of its lack of being in the running for "most toxic". --24.147.69.31 (talk) 15:54, 16 January 2008 (UTC)

It's all about how you use it. A few kilograms of plutonium can kill an awfully large number of people.  ;-) Dragons flight (talk) 17:46, 16 January 2008 (UTC)

Wink all you want, but that's not toxicity, and a few kilograms of plutonium by itself does nothing unless you have a lot of other apparatus. And even if you did take that definition of it, it is still nothing compared to botulinium toxin, where "a few hundred grams could theoretically kill every human on earth". Even taken for its role in nuclear weapons, pound for pound it's still not even in the running for most toxic substance!! --24.147.69.31 (talk) 18:04, 16 January 2008 (UTC)

The reason that plutonium being considered the most toxic substance is debatable is due to the fact that it has the ability to sustain its toxicity for a very very long time. Most poisonous/toxic substances kill or maim their victims and then are depleted or used up in the process. Plutonium, on the other hand, has a very long half life (80 million years or so, give or take a decade), which means that it will continue to be highly toxic for ... well ... forever basically. So, if say a major earthquake took out one of the dams on the Columbia/Snake River system above the Hanford Site, which has quite a bit of plutonium on its premises, there could theoretically be a resulting chain reaction of dam failures all the way down the Columbia River to the Pacific Ocean, with the flood waters also theoretically carrying much of the plutonium from Hanford. If such a calamity was to take place the result would be that a largish amount of plutonium would be dumped with the flood into the Pacific, resulting over time in destroying all life in the entire Pacific Ocean basin as the ocean currents spread it around. The reason for this is not because plutonium is highly toxic immediately, but because of its very long-lasting quality which means it continues to kill and kill and kill without being consumed or destroyed in the process.

THAT is the reason that some people use to support the thesis that plutonium is the most toxic substance known to man, and that is why it is debatable. It all depends on what you mean when you say something is toxic - do you mean is it toxic in the short term or the long term. If in the short term, then plutonium is not the most toxic. But if you mean what is the most toxic substance in the long term, then plutonium wins hands-down as being the most toxic substance. -- Saukkomies 08:30, 17 January 2008 (UTC)

No, the reason some people support that "thesis" is that they want to frighten people by irrational arguments. They seem to have succeeded with you. --Anon, 17:46 UTC, January 17.

Have you ever heard of the concept of concentration? If you were to dump the entire contents of the Hanford holding tanks into the Pacific and mix well, the average glass of water would contain no plutonium. The Hanford tanks may be large on a human scale, but on a human scale, the Pacific is bloody huge and then some. --Carnildo (talk) 21:49, 17 January 2008 (UTC)

Well, the average glass of water would contain some plutonium, but not enough to worry about.

As for Saukkomies's point about the lifetime of the substance -- elemental poisons, such as lead or arsenic, last forever (or close enough for government work--I'm not taking proton decay into account, obviously). Many other industrial poisons and carcinogens, such as polycyclic condensed aromatics or dioxins, might degrade eventually, but not soon enough to consider them a temporary problem. Basically I can't see plutonium at the top of any list of nasties not involving intentional aggression. I think it's important to refute this meme about plutonium, which is a very dangerous one, as it could prevent the expansion of nuclear power, which is one of our best hopes for reducing carbon emissions. --Trovatore (talk) 22:08, 17 January 2008 (UTC)

(Margin readjusted)

Okay, first off, plutonium is not necessarily connected with nuclear energy. There are plenty of nuclear reactors that do not use plutonium and do not make plutonium. So the point about being aware of plutonium's nasty nature has very little bearing on that subject.

Second, per the discussion about plutonium being able to kill off all life in an ocean basin, please refer to the various articles published in peer-reviewed professional/academic journals that basically state how this is a possibility:
- "Plutonium protest", by Cheftel, Julia. Chemistry & Industry no20 (October 18 2004)
- "Disposing of the world's excess plutonium", by McCormick, James M.; Bullen, Daniel B. Policy Studies Journal v. 26 no4 (Winter 1998) p. 682-702
- "A sea of troubles: how plutonium came back to plague us", by Busby, Chris. The Ecologist v. 29 no7 (Nov. 1999) p. 396-7
- "Pu by the ton", by Moore, Mike. The Bulletin of the Atomic Scientists v. 53 (March/April 1997) p. 44

The Reference Desk is not meant to be used as a forum for people to push their own personal agenda or theories, so unless someone has any solid proof that refutes the fact that plutonium is capable of destroying life in an ocean basin (as is outlined in above cited journal articles), then I would suggest the discussion be taken elsewhere, as it is merely opinion. -- Saukkomies 17:32, 17 January 2008 (UTC)

So it's not true that the question has little bearing on the subject of nuclear power. Right now we're using uranium reactors, but it stands to reason that if nuclear power is to substitute the role currently played by fossil fuel, we will eventually need breeders.

However I concede that I haven't read those articles and can't directly comment on them. --Trovatore (talk) 22:57, 17 January 2008 (UTC)

Salty water

I was surprised to realise I didn't know why sea water is salty, so looked up Seawater.

I understand Halley's theory (my inexpert summary: salts leached from ground by run-off go into the sea) but the next parag flummoxed me:

Halley's theory is partly correct. In addition, sodium was leached out of the ocean floor when the oceans first formed. The presence of the other dominant ion of salt, chloride, results from "outgassing" of chloride (as hydrochloric acid) with other gases from Earth's interior via volcanos and hydrothermal vents. The sodium and chloride ions subsequently became the most abundant constituents of sea salt.

None of this makes any sense to me - can it be explained here and in the article? --Dweller (talk) 15:25, 16 January 2008 (UTC)

Well, salt is chemically composed of two ions (two charged atoms), sodium and chloride (making sodium chloride, written chemically as NaCl). All it's saying, once you know that, is that there was a lot of sodium in the ocean floor and that a lot of chloride was released through vents and volcanos, and these combined to make salt in the water, thus became salt water. --24.147.69.31 (talk) 15:42, 16 January 2008 (UTC)

Also, salts leached by groundwater are actually coming from salt deposits layed down by ancient extinct seas that are now located in land that is above sea level. Salt is created in the ocean (see the above response for this), not on dry land, and therefore if it is found on dry land, it is an indication that that portion of land used to be underwater at some point in the geologic past. Because salt does not evaporate, it is left behind when water evaporates into the atmosphere. This is also why salt is in the oceans - it cannot escape because it is in the bottom of the drainage system of the world's water cycle. When water evaporates from inland seas it leaves large deposits of salt behind, which then over time get covered by other soils and form salt deposits. -- Saukkomies 10:59, 16 Janyary 2008 (UTC)

Ah! Among other things that confused me, was "leached out of the ocean floor". I thought it was saying it leached from the ocean to... somewhere else (gawd knows). All of the above makes sense. If someone who understands what they're talking about and can string a sentence together (either of you guys, for starters!) could improve the article that'd be great. --Dweller (talk) 16:07, 16 January 2008 (UTC)

determination of percentage for aspirin

how do we determine the percentage of aspirin and why? —Preceding unsigned comment added by 82.146.171.139 (talk) 18:46, 16 January 2008 (UTC)

What do you mean by "percentage of aspirin"? -- Coneslayer (talk) 19:21, 16 January 2008 (UTC)

Sounds like a homework problem. I'd use a balance scale to determine the mass of an aspirin tablet, then compare that against the reported milligrams of active ingredient in the tablet. A little math, and you've got a percentage. --Mdwyer (talk) 23:59, 17 January 2008 (UTC)

Does stretching a muscle increase muscle mass?

Hi, Suppose subject A has a hamstring muscle that weighs 3.0 lbs. Subject A proceeds to stretch that muscle over a period of a month, say. So that the muscle is now 1.05 times the length than before. Does this stretched muscle grow larger so that the muscle now weighs more than 3.0 lbs? Or does the muscle stretch out and become thinner, so that the muscle stills weighs 3.0 lbs?

I ask this question because in stretching muscles I often feel a kind of burning sensation, as if I were working out. Also, after stretching, some of my muscles do feel a little sore (in a good way).

Thanks! --InverseSubstance (talk) 19:32, 16 January 2008 (UTC)

Stretching is not a recognised way for Muscle building. Instead contracting muscles under load can boost mucle mass. (eg weightlifting) Graeme Bartlett (talk) 01:43, 18 January 2008 (UTC)

Actually the relevant WP article is at strength training; weightlifting, according to the article, is a sport rather than an exercise. Not sure that agrees with common usage, but I suppose it's a sensible distinction. --Trovatore (talk) 01:48, 18 January 2008 (UTC)

Car polution

Why dont we just put CO2 filters in the exhaust pipe of cars. —Preceding unsigned comment added by Sivad4991 (talk • contribs) 20:12, 16 January 2008 (UTC)

Filtering it from the air doesn't stop it from being made. Bellum et Pax (talk) 20:17, 16 January 2008 (UTC)

what, by that reasoning having all the pollution in the air worldwide in a huge, giant (very large) vault next to Fort Knox wouldn't give us cleaner air. Of course it would, and the question is a legitimate one. Reducing air pollution is about...reducing air pollution. —Preceding unsigned comment added by 212.51.122.4 (talk) 20:26, 16 January 2008 (UTC)

The key question , of course, is: "Having filtered it out, where does the car store it? And then where do you put it?" Our article about carbon sequestration may help to provide some answers about the latter half of the question but even the first half requires tricky technology. A big tank of lime water maybe?

Atlant (talk) 20:50, 16 January 2008 (UTC)

Not quite the same but a lambda sensor work on making a car more emission efficient. This forum posting (http://forum.physorg.com/index.php?showtopic=5478) seems to go into more details about CO2 filters from a "would they work" viewpoint.ny156uk (talk) 20:38, 16 January 2008 (UTC)

A) There aren't any efficient, small-scale filters specifically for CO2. B) Even if you could trap all the CO2, it would be quite hard to store. At atmospheric pressure you'd need about 10 m^3 of space for each gallon of gasoline. An onboard gas compressor wouldn't be impossible, but greatly increases the technical difficulty. By comparison, the catalytic converters on a car improves exhaust by passively converting some toxic gases into less toxic gases. No energy input is required and the results still get dumped into the air. Unfortunately, because CO2 is already fully oxidized there is no easy way to convert it into anything else. Dragons flight (talk) 20:53, 16 January 2008 (UTC)

self-heating food

so if I want to drink coffee hot that I prepare in the morning I can bring a small thermos with me. what can I bring that almost fits in a pocket that gets warm or stays warm, like an mre. —Preceding unsigned comment added by 212.51.122.4 (talk) 20:22, 16 January 2008 (UTC)

Something in a Self-heating can, perhaps? --LarryMac | Talk 20:30, 16 January 2008 (UTC)

yeah but does it have to be a can? i dont want to eat my gourmet spaghetti creation I made in the morning and that beats the local options where I work...from a can. What can I do? in my case, I think something exothermic I can mix into my tuppperware and stir around a bit would work fine. Does anything self-heat? —Preceding unsigned comment added by 212.51.122.4 (talk) 20:57, 16 January 2008 (UTC)

In general, exothermic substances are also going to be toxic/caustic. Self-heating cans, and the like, are able to work because the heating element is seperated from the food by barrier. Dragons flight (talk) 21:04, 16 January 2008 (UTC)

I was thinking, like little sealed balls I could mix with my food for a while, and then just not eat those. or, a sealed container (not a can!) that self-heats from a reaction in a sealed-off part. If MRE's can self-heat, why can't i buy something that does the same thing. is it a controlled substance or dangerous or something, hence only suitable for soldiers. thank you! —Preceding unsigned comment added by 212.51.122.4 (talk) 23:21, 16 January 2008 (UTC)

It appears you can buy the "ZestoTherm" heating pouches used with MREs for $10 / dozen from camping/survival stores. For example: [11]

To answer the other point, yes, the things are potentially dangerous. The calcium oxide used in many self-heating cans will eat away skin. It appears that the MREs version uses less dangerous chemicals, but even so it should also be treated with respect. Dragons flight (talk) 00:27, 17 January 2008 (UTC)

A hamster or a mouse or small kitten?--TreeSmiler (talk) 01:44, 17 January 2008 (UTC)

One can get wide-necked thermos flasks for food. DuncanHill (talk) 22:18, 17 January 2008 (UTC)

Memory Battery

are memory batteries for cell phones real or are they a myth 'EDIT': what i meant was do the batteries that come with a phone have a memory function so that it requires you to use your battery until its dead before you can charge it again. i9 have heard people say the if you dont let you battery run down before charging it again you will shorten the battery life and the the amount of time it will stay charged.—Preceding unsigned comment added by 71.98.94.8 (talk) 20:25, 16 January 2008 (UTC)

Do you mean the little flat things that keep the date/time/basic information while you've got the main-battery out/turned off? They must have something as my phone doesn't lose its memory of time when I turn it off/take out the battery and it would need some form of power to keep time (unless it gets the time from the mobile-signal or kinetic energy). ny156uk (talk) 20:32, 16 January 2008 (UTC)

Those little flat things in cell phones are SIM cards, but I'm not quite sure what you, 71.98.94.8, are referring to. Someguy1221 (talk) 20:49, 16 January 2008 (UTC)

Ultracapacitors may also play a roll here, but I'm just speculating.

Atlant (talk) 20:52, 16 January 2008 (UTC)

While memory batteries aren't a myth, they're not strictly necessary for a cell phone, either. Data like settings and contact lists can be (and virtually always are) stored in flash memory, which is non-volatile (that is, it doesn't require power to maintain state). Time information is not suited for such memory, since it's updating continuously, but cell phones draw that information from local towers. It would seem a reasonable compromise to allow a phone to lose time information knowing that it will be automatically regained when a tower signal is next received. — Lomn 20:54, 16 January 2008 (UTC)

Cell phones remember what time it is after turned on without having to connect to a tower for updates, so presumably draw some minimal power for a clock. Some samsung phones, from my personal experience, could actually be programmed to turn themselves back on at a specified time. I never thought to remove the battery and check if the clock was still accurate minutes later, probably worth doing (but not for me, since the battery on this phone is an absolute pain to remove). Someguy1221 (talk) 23:32, 16 January 2008 (UTC)

(No longer the OP's question, but I'll address it anyway) Mostly what you're describing, though (certainly the Samsung wakeup thing) is with the main battery still installed. I was attempting to address why you don't have to manually set your cell phone's clock/contacts if you remove the battery and replace it. — Lomn 15:59, 17 January 2008 (UTC)

Ahhh! Now that's different! Modern cell phones almost all use lithium-ion batteries or lithium-ion polymer batteries. These, like most rechargeable batteries do not want to be deep-cycled; you should top off the charge whenever possible. Only the much-older nickel-cadmium family of batteries needed occasional full discharges to keep working well, allegedly due to the memory effect.

Atlant (talk) 23:35, 16 January 2008 (UTC)

renewable energy street lights

I went to hanauma bay over vacation and I realized that on the street lights in there parking lot there is a little fan that I think powers a little generater and I also think there was a little solorpanel on the top that was only about as big a the top of a normal street light. Iwas wondering how much all of that would cost. And on the plane ride i noticed that the cities are yellowy orange because of the yellowy orange street lights.Are the yellowy orange bulbs more effitiont than the energy effitiont bulbs they are trying to get people to use in there house? thanks --Sivad4991 (talk) 20:25, 16 January 2008 (UTC)

The yellowy-orange lights are sodium vapor lamps and these are currently the most-efficient light sources available. The low-pressure lamps are extremely efficient but monochromatic; the high-pressure kind are less efficient but allow you to see some colors other than sodium yellow. Neither kind gives a good-enough color-rendering index to be acceptable to light home interiors.

Atlant (talk) 20:43, 16 January 2008 (UTC)

The low-pressure sodium lamps are favored by astronomers, because the light pollution they generate is more easily filtered out than that from other types of lamps. Hence, you will often see LPS streetlights in cities and communities near astronomical observatories. -- Coneslayer (talk) 20:46, 16 January 2008 (UTC)

Sodium vapor lamps (the yellow ones) are quite energy-efficient. Our article on the history of street lighting in the United States doesn't directly compare the efficiency of SVLs with CFLs, but notes that CFLs don't last as long and don't perform as well in cold weather. As for the charging assembly, I wonder if the fan might actually be a cooling fan rather than a turbine. — Lomn 20:49, 16 January 2008 (UTC)

Carbon Monoxide resonance forms

According to this site, the leftmost form is the most contributing. Why? Shouldn't the neutral one be the most contributing? I'm thinking that because it is neutral, it is more stable than the other polar forms. 199.76.154.127 (talk) 21:57, 16 January 2008 (UTC)

Neutral does not imply more stable. This can be seen most easily in this case with a molecular orbital diagram. In the case of carbon monoxide, the three P-orbital bonds available are all lower in energy than the lone pairs around either atom. So when looking at the middle resonance structure, the energy of the molecule can be lowered by having oxygen donate one of its lone pairs to a third bond with carbon. Carbon can't donate any as it has already "run out" forming the existing bonding and anti-bonding pairs (although in reality you can't actually tell where they came from, they all just make their way to the lowest orbitals available, and this website might make that clear to you, just search for "carbon monoxide" to jump to its diagram). As a rule that may be easier to understand, carbon's tendency to achieve an octet overpowers oxygen's tendency to not be positive. Actually, even when carbon's octet isn't at issue, having a major resonance structure with a positively charged oxygen atom is typical of many molecules with C-O bonds. Someguy1221 (talk) 23:07, 16 January 2008 (UTC)

Thank you. I will be looking at the pi orbital site, as right now I'm not too familiar with the details of orbitals. But you said something about the octet rule. When figuring out the most stable form of a molecule, does requirement for octet rule always trump everything else, no matter what kind of atoms are involved?199.76.154.127 (talk) 03:07, 17 January 2008 (UTC)

In general chemistry, the only octet-breaking situations you should ever encounter are complex ions, which (hopefully) obey the 18-electron rule, the central atom of some mineral acids, and boron. And as a tip for oxygen and resonance structures, it is usually OK for an oxygen bound to a carbon to carry a positive charge if all octets are satisfied and either A) another oxygen carries a negative charge or B) the overall charge on the molecule is positive (and in CO, of course, as this is the only way to satisfy octet). As a formality, the lewis structures of many boron compounds have only six valence electrons around boron (which is sometimes but not always accurate). In any event, when this is the case you can usually predict (at least, I know of no exceptions) that the compound will bind to lewis bases. Someguy1221 (talk) 05:48, 17 January 2008 (UTC)

Date genus Bubo was first given(for want of a better word)

I wish to know the aproximate date that the genus bubo was first given to an owl, Horned Owl Blacksmith ^talk 23:20, 16 January 2008 (UTC)

The article says 1806 (in the infobox). (EhJJ) 02:03, 17 January 2008 (UTC)

January 17

Macaw training

I've seen videos on YouTube of macaws and other parrots rolling over, lying on their backs with their feet in the air, relaxing and allowing their owners to tickle their bellies. How can I train my Hyacinth Macaw to do this too? I've tried to very gently get my hand underneath and flip her over when she's playing on the floor but she absolutely hates it. —Preceding unsigned comment added by 84.69.34.141 (talk) 00:05, 17 January 2008 (UTC)

Itchy ears

When Ive had earphones in for a while, the insides of my ears start to itch. Any reasons?--TreeSmiler (talk) 01:37, 17 January 2008 (UTC)

Conjecture: they vibrate enough to tickle you. --Anon, 05:49 UTC, January 17, 2008.

It may be that they are bad fit. But wearing earphones (or hearing aids) for long periods is not a good idea. They encourage a buildup of moisture in the ear which can lead to infection. In any case you should clean and disinfect the earphones regularly. Headphones are safer and give much better sound quality.--Shantavira|^{feed me} 09:54, 17 January 2008 (UTC)

Unless, of course, they are those Bose earphones. 206.252.74.48 (talk) 13:38, 17 January 2008 (UTC)

Momentum Of A Chicken

Hey,it`s Me the physics magazine guy again sorry you all got upset over the last two questions.I made up the whole prize thing.But,I really need you guys to answer another question for Me.I tried doing,this one twice.Iam,supposed to figure out the momentum of a chicken. 1.75 seconds. —Preceding unsigned comment added by 68.161.69.238 (talk) 01:43, 17 January 2008 (UTC)

0. It isn't moving. Or are you talking about a different chicken? Algebraist 01:56, 17 January 2008 (UTC)

I would think that MOMENTUM_CHICKEN = MASS_CHICKEN x VELOCITY_CHICKEN. (EhJJ) 01:59, 17 January 2008 (UTC)

Assuming, of course, that it's a non-relativistic chicken, i.e. that $\gamma _{\mathrm {chicken} }\approx 1$. —Keenan Pepper 03:16, 17 January 2008 (UTC)

Depends on whether you're in the frame of reference of the chicken, or the road it's crossing. Confusing Manifestation(Say hi!) 03:26, 17 January 2008 (UTC)

Since momentum relies on velocity and the velocity of the chicken can be referenced to any object in the universe, then the momentum of a chicken can take on any value you wish to give it (quoting the datum point of course)--TreeSmiler (talk) 05:34, 17 January 2008 (UTC)

It might help if you told us the actual question (yet somehow I doubt it).--Shantavira|^{feed me} 09:45, 17 January 2008 (UTC)

Rocket in vacuum

I know it has been asked here before, but I can't found it using google. I also can not found in wikipedia's articles. So the question is how rocket could work in vacuum? roscoe_x (talk) 03:42, 17 January 2008 (UTC)

Rockets in space are working in a vacuum and I don't know all the physics behind it, but a rocket carries its own fuel and its own liquid (compressed) oxygen to burn that fuel. When it does so, the burning gas is hot and expands and forces itself away from the rocket. This pushes the rocket in the opposite direction (this phenomenon is known as conservation of momentum - you can't have something being pushed left without an equal force being applied in the opposite direction (right)). The fact that it's a vacuum is even better, because then the rocket doesn't have to work against air-resistance like everything below the Earth's atmosphere must. For rockets that are still leaving the atmosphere, air-resistance can be a real drag. ----Seans Potato Business 03:56, 17 January 2008 (UTC)

Excellent summary. Also note that solid fuel rockets can blend the oxygen directly into the fuel without carrying a separate tank. No practical difference from a physics standpoint, and frequently less practical (you can't kill the valves on a solid fuel engine). I'll also note that the expansion of exhaust isn't so much a function of heat as one of state transition -- a gas expands to fill far more volume than a liquid simply by being a gas. While a hotter gas exerts more pressure than a cooler one, this is a comparatively minor effect for rocketry. — Lomn 05:17, 17 January 2008 (UTC)

Both of those responses are great. I just wanted to add an illustration to maybe make this easier to understand. Think of something exploding in space - like for instance the famous scene in the first Star Wars movie when the Death Star blows up. As it explodes it projects stuff outward in all directions into space. Now, what is taking place inside a rocket is basically a controlled explosion. The rocket's fuel is exploding, and it wants to project outward in all directions. However, because of the engineering of the rocket the explosion is only allowed to escape in one direction. The resulting pressure on the rocket in the other direction means that the rocket is pushed away from the explosion going on inside of its engine in the direction away from its nozzle. Hope that helps, and if it's any consolation, this very question used to bother me a lot, too. -- Saukkomies 08:40, 17 January 2008 (UTC)

Would it be correct if we used a depiction of two people that push each other, one move to front and the other move backward. The one who move to the front is the rocket and the one move backward is the fire. roscoe_x (talk) 15:46, 17 January 2008 (UTC)

Yep, that's exactly the principle. It's even more elegant if you can put them on skateboards, roller skates, or some other free-rolling platform (to prove that it's the push and not just two people walking), but the illustration is correct regardless. — Lomn 15:56, 17 January 2008 (UTC)

all of the above makes sense - but would the rocket move faster if there was some 'mega platform' - completely immovable (due to magic, mirrors and/or duct tape for the sake of argument) - for the exhaust to push against? 83.104.131.135 (talk) 17:10, 17 January 2008 (UTC)

No. Rockets do not work by "pushing against" their surroundings. Suppose you have a rocket, which releases a molecule of exhaust with momentum Δp. Due to conservation of momentum, the rocket's momentum changes by −Δp; that is, the rocket gets a kick in the opposite direction of the exhaust. Now, if at some later time, that molecule of exhaust hits a barrier, or whatever, what effect does it have on the rocket? None. The rocket's gone on its way. What happens to the exhaust after it leaves the rocket is immaterial. -- Coneslayer (talk) 17:26, 17 January 2008 (UTC)

Just to head off a possible objection or follow-up question.. If the surroundings allow pressure to build up behind the rocket, that pressure will push it, much like the pressure behind a bullet pushes it down the barrel of a gun. However this is a separate action from the actual rocket propulsion. Friday (talk) 17:36, 17 January 2008 (UTC)

Yeah, I think that would be internal ballistics, not rocketry. -- Coneslayer (talk) 17:41, 17 January 2008 (UTC)

Camping lantern - glowing white netting

I found a gas camping lantern and over the holes from which the gas comes, is a sort of white netting. When I touched part of the netting, it disintegrated (possibly a function of age or maybe it was always fragile). The function of the netting appears to be to glow white when it gets hot. What is this netting? Why is it fragile? Since the gas appeared to be burning with a blue flame, is it likely that it was burning with a clean, CO-free flame? ----Seans Potato Business 03:47, 17 January 2008 (UTC)

It's called a mantle. I believe it's a surface catalyst on which the fuel gas burns more efficiently and with a brighter, whiter flame. Read the article for how it works -- I had no idea. —Steve Summit (talk) 03:58, 17 January 2008 (UTC) [edited 04:03, 17 January 2008 (UTC)]

Years ago Coleman lanterns (fueled by white gas) had a thorium mantle which looked like a little cloth drawstring bag. It would be lit initially and burn to ash, which retained the shape. Then the mantle would glow when the gas burned, producing far greater brightness than the mere burning gas vapor. After it was initially burned, it was very brittle and would disintegrate when touched, Untouched, it would work for a long time. Something like that seems to stilll be used [12]. The mantles reportedly switched from thorium to less radioactive substances which produce about 20% less light. The mantle is actually an incandescent light (though not electrical) which dates back to the Welsbach mantle of 1884 [13]. Edison (talk) 01:15, 18 January 2008 (UTC)

Coleman has generally replaced thorium with yttrium in its mantles; this actually gives a whiter, brighter light than the thorium did. Cheers Geologyguy (talk) 01:34, 18 January 2008 (UTC)

A proton and electron in an atom

Why don't they just stick together?199.76.154.127 (talk) 04:46, 17 January 2008 (UTC)

the answer to this very innocent question lies in quantum mechanics. I don't quite have a layman's explanation for it. (by the way, the explanation that it's in "orbit" around the nucleus is absolutely wrong) —Preceding unsigned comment added by 18.96.6.229 (talk) 05:00, 17 January 2008 (UTC)

The "simplest" (ha!) explanation is that electrons don't completely behave like "particles" in the common-world-experience sense. There isn't precisely a negatively-charged object to stick to a proton—there's a lot more going on. See Atomic orbital model#Current theory for some introduction to the situation. DMacks (talk) 05:10, 17 January 2008 (UTC)

That sad truth is that you can only understand the complete answer once you know how to prove such an atomic configuration is not a stable solution of the Schrödinger equation. As the first lie on the step to that understanding, you might be interested in the Bohr model. Someguy1221 (talk) 06:05, 17 January 2008 (UTC)

A hydrogen atom in the ground state is just a proton and an electron "stuck together". The electron doesn't orbit the proton, it's simply superimposed on it. They don't collapse to a point because the uncertainty principle forbids it. A decrease in position uncertainty beyond a certain point implies an increase in momentum uncertainty which leads to an increase in position uncertainty. Instead they settle into an equilibrium state where these two effects balance out. The electron ends up with a much larger uncertainty of position because its much smaller mass means that a small uncertainty of momentum counts for much more in terms of velocity. That's why the atom looks like a small nucleus of positive charge surrounded by a big cloud of negative charge. For larger atomic numbers the exclusion principle also comes into play. -- BenRG (talk) 13:01, 17 January 2008 (UTC)

Speaking of lies: Ben, you have given the lie to 18.96.6.229, DMacks, and Someguy1221, who said it couldn't be done. That was a beautiful, simple explanation. —Steve Summit (talk) 16:41, 17 January 2008 (UTC)

Thanks for the inputs everyone. So I guess the reason an electron doesn't come into contact with a proton is due to its fundamental make-up of the electron, with the behavior that obeys the uncertainty principle. The proton, on the other hand, does not have the behavior described by the uncertainty principle (correct me if I'm wrong). That begs another question: Why does the electron have such a weird behavior? 128.163.174.150 (talk) 23:33, 17 January 2008 (UTC)

The proton does obey the uncertainty principle. Remember that ΔxΔp>h/2 (p = mass*velocity) or however you want to represent it. Since the proton happens to be 2000 times as massive as an electron, its uncertainty in velocity or position can be a lot smaller than the electron's. Someguy1221 (talk) 23:43, 17 January 2008 (UTC)

LASER mixing questions

Let's say, hypothetically, I managed to attach three different gain mediums to one device, each emitting a different color (Red, Blue and Yellow, unless green really is a better color for this), and used a lens to focus them into one point. What is the resulting color, or does it fail entirely? Silverfireshadow (talk) 06:15, 17 January 2008 (UTC)

I assume you're talking about just superimposing beams upon one another, and not frequency mixing. You'll get a new color (in appearance only. In fact, you just have three superimposed waves), and you might be able to predict it from the visual color wheel. Someguy1221 (talk) 06:23, 17 January 2008 (UTC)

You're probably want to try it with Red Green and Blue, if you're trying to mix lights to produce (visually) white light, (or vary the intensities to get a full visual spectrum.) A company called Microvision has announced a pocket-sized digital projector based on this technique. APL (talk) 14:17, 17 January 2008 (UTC)

This has been done for a very long time. I visited a place (Magic-Stage if memory serves) in N. Carolina's research triangle that used tri-color lasers to produce 3D holograms on a stage that interacted with humans. The holograms looked very real. They just didn't cast shadows. The primary clients came from Las Vegas (magicians and concert stage shows). It is very easy to make your assistant disappear when she is just a hologram. -- kainaw™ 14:52, 17 January 2008 (UTC)

A doorbell that rings itself

As if kids pulling pranks wasn't bad enough, my parents have a doorbell that rings itself - what can be done? They and one neighbor - me - each have the same type of wireless doorbell, as does a third person across the street. For some reason, for the last few years, wehenver we've had the same type of doorbell, when one of ours rings, the other rings - and sometimes the one across the street does, too. We don't know if they've replaced theirs, but when one of us replaced a doorbell, then when both replaced, the same thing happened. Last night, both our doorbells suddenly started ringing "off the hook." (Old fashioned term for when phones still were put on hooks :-) So, we unplugged them. This had happened before if one of ours got a short because of tons of rain, but we have not had rain for several days, so they were not wet. Is there a long-term solution to these doorbells that seem to pull pranks? Why are our houses so inexorably linked by doorbell?Somebody or his brother (talk) 14:05, 17 January 2008 (UTC)

Long term solution. DuncanHill (talk) 14:09, 17 January 2008 (UTC)

Usually wireless things like this have a way of setting "channels" so that you can't accidentally set someone else's off with the same frequency. You'd have to consult their manuals though. --24.147.69.31 (talk) 14:27, 17 January 2008 (UTC)

Even with separate channels, you'll get interference on wireless doorbells that causes them to ring. My father-in-law lives in one of the heavily pre-planned neighborhoods where very house is identical and all have identical wireless doorbells. There were many complaints about doorbells ringing and they called out an electrician to try and figure it out. After a few months, it was discovered that the doorbells were ringing as the police drove through the neighborhood doing nightly patrols. Something (who knows what) was coming from the patrol car and causing the doorbells to ring. They switched out all the doorbells to a different model of wireless doorbell and the problem was solved. Personally, I would have dumped the whole wireless thing and put a wired one in. They aren't more expensive and they are very easy to install. Of course, that is only if you want a doorbell. I have a Victorian-style turnbell on my door. No electricity needed. Just turn the butterfly handle and it rings. -- kainaw™ 14:50, 17 January 2008 (UTC)

Sorry to give you a question rather than an answer, but what is the point of a wireless doorbell? I feel like I'm missing something here. Algebraist 15:02, 17 January 2008 (UTC)

To save you the effort of running (and concealing) wiring from the button to the chime. -- Coneslayer (talk) 15:08, 17 January 2008 (UTC)

(ec) In retrofitting a home that didn't have a doorbell, going wireless saves the homeowner/installer the trouble of drilling holes and pulling wire through walls. In new construction, the walls are open anyway, so the 'ease of installation' argument is weaker. As well, it allows one to relocate either the button or the bell component fairly easily. While it's unlikely that the front door will move very often, a homeowner might want to have the bell component located far from the door: in the basement near the television, for example, or up in the attic near the home office, or out in the garage workshop. A wireless system avoids long cable runs, allows the 'bell' to be relocated easily, and some systems are designed to permit the easy installation of more than one bell. TenOfAllTrades(talk) 15:15, 17 January 2008 (UTC)

My thanks to both of you. Algebraist 16:59, 17 January 2008 (UTC)

Thanks to all; interesting about the police cars, I actually was thinking while walking the dog of how our college radio station would interfere with the physics department's lab, and wondered if there was some outside interference. I'll have to see if the manual says anything about changing channels.

As for the movability of the bell, yes, not only was there no bell, when I bought this house it didn't even have a side door - and the front was stuck shut. (Poor widow didn't keep it up well, & always left out the garage. Sad situation, but I got it for a good price, and after some fixing up it's been really nice.) —Preceding unsigned comment added by DTF955 (talk • contribs) 15:24, 17 January 2008 (UTC)

what you do is you open up the push switch and ringer (with a screwdriver) and you'll see about eight tiny switches inside each of them set identically for each (up or down). what ya do is change some of the switches from up to down etc and make sure you do the same for both. this chnages the frequency it transmits and receives on and now you wont get no interferience from your neighbors. good luck mate! xxx User:Hyper Girl 15:25, 17 January 2008 (UTC)

To pick a nit, the switches probably change the binary code transmitted by the doorbell, but not the frequency. If the problem is your bell rings when the neighbor's button is pushed (and vice-versa), this will fix it. If the problem is radio frequency interference that's "faking out" your doorbell receiver, this probably won't fix it.

Atlant (talk) 19:27, 17 January 2008 (UTC)

To Algebraist: I think a wireless doorbell could make sense in a detached house where the button is on the garden gate, and the bell is in the house. – b_jonas 17:17, 17 January 2008 (UTC)

Canalphones

I'm looking for the reason canalphones give such superb bass response (reportedly down to 2 Hz). How is it done?--TreeSmiler (talk) 15:59, 17 January 2008 (UTC)

Because of the very small volume of air between the canalphones and your eardrums, they only have to move a teeny tiny bit of air to make your eardrums move strongly.

Atlant (talk) 19:30, 17 January 2008 (UTC)

What about the extremely small enclosed volume of air behind the diaphragm that has quite a low acoustic compliance, putting up the resonant frequency of the system?--TreeSmiler (talk) 02:43, 18 January 2008 (UTC)

Electrostatic Problem

Dear All, It would be very nice of you if you can help me.Well these are two problems of Electrostatics which I cannot find an answer.The first one I do not have any idea. The second one I've got some way but I have difficulty in finding the projection of AB.Please help me out and this is not part of any homework.

1)A rod of length L lies along the x-axis with its left end at the origin.It has a nonuniform charge density k=ax, where 'a' is a positive constant. Calculate the electric potenetial at point A where x=-d?

Ans:(1/4πЄ) * a[L-d(ln(1+(L/d)))]

2)A uniform electric field of 100V/m is directed at 30 degree with positive x-axis as shown in figure. Find the potential difference V_BAif OA=2m and OB=4m?

The attached

Thanks in Advance. Oasa (talk) 16:25, 17 January 2008 (UTC)

I assume you know the basic formula for the electrostatic potential generated by a point charge. Given this, (1) is an easy integral. Algebraist 18:05, 17 January 2008 (UTC)

Why do newer rifles have a lower rate of fire (typically) than older rifles?

For example, the XM8 has a lower rof than the M16. Why? 64.236.121.129 (talk) 17:45, 17 January 2008 (UTC)

I don't know whether it's really true that this is a general trend, not following military rifles much, but I can think of some reasons why this might be true. High rate of fire isn't necessarily an advantage with a rifle. You're going to have less manageable recoil, and more heat build-up as your rate of fire increases - not to mention the potential to waste more ammo more quickly. Keep in mind, these are just rifles; they're not meant to be used as machine guns, and they certainly can't sustain a rate of fire anywhere near the maximum rate of fire. Whether the slightly lower rate was intentional or not in this particular rifle, I don't know, but I doubt it was seen as a disadvantage. Even on the venerable M16, they fairly quickly abandoned full-auto for most purposes, in favor of a 3 round burst. Full autos require more discipline from the troops using it, to be effective. Contrary to what the movies imply, just making more bullets fly around isn't generally much of an advantage. Friday (talk) 18:21, 17 January 2008 (UTC)

Unidentified Plant

Can anyone help me identify this [[14]] plant? I would be very grateful if anyone has any ideas! Thanks, Aiyda 18:04, 17 January 2008 (UTC)

No, but when someone competent turns up, it'll help if you tell them where you found it. Algebraist 18:08, 17 January 2008 (UTC)

Apologies, the picture was taken in the Ashdown Forest in East Sussex. Aiyda 18:10, 17 January 2008 (UTC)

It looks a lot like a day lily. --Milkbreath (talk) 18:53, 17 January 2008 (UTC)

MESSENGER and the white spot

Two of us were looking thru MESSENGER's latest returns and were discussing the impact craters. What might the white spot be in this one (lower right side)? We're speculating its glass from a dead-on impact, since a large portion of Mercury's crust is composed of silicates. Its also interesting to note that the other white spots don't always appear to be in craters. We've disregarded volcanic activity. Inquiring minds want to know. --LeyteWolfer (talk) 20:49, 17 January 2008 (UTC)

It could be smashed up rocks, eg puverized grit, it would not be just glass, but it could be broken glass. Graeme Bartlett (talk) 22:30, 17 January 2008 (UTC)

For the moon I know that young craters often have brighter appearance that dulls over time. I would assume the same is true of Mercury. In this context "young" may include tens of millions of years. Dragons flight (talk) 00:17, 18 January 2008 (UTC)

Does wood burn faster in colder temperatures?

Tried to find the answer to this one for some time. Thought you guys might be the key. Does wood burn faster in colder temperatures, all other things being equal? Discussion started when one friend asserted that her wood burner went through fuel faster in colder temperatures. Of course in colder temperatures she uses more wood, but is the rate of combustion faster? —Preceding unsigned comment added by Tanthalas39 (talk • contribs) 21:26, 17 January 2008 (UTC)

Can't really see why; the combustion temperature of the wood is going to be the same in any event. What's a 30 degree swing in environment when you're burning at 500K? — Lomn 21:30, 17 January 2008 (UTC)

Faster convection with the outside air? Someguy1221 (talk) 21:40, 17 January 2008 (UTC)

I can imagine perhaps some relationship between how much fuel is in the burner, and the rate of burning. And, since you put more fuel in at once when it's colder... Friday (talk) 21:44, 17 January 2008 (UTC)

As an ex-firefighter for the US Forest Service, I recall that in Fire School we were taught that forest fires burned a lot more intensely on hot days. When the temperature is lower a forest fire will burn more slowly. Now, whether that means that the wood burns faster or not is unclear to me. -- Saukkomies 17:39, 17 January 2008 (UTC)

Cold air is denser, and so may provide more oxygen to a fire than a comparable volume of warm air, but it really feels like a stretch. Still, you might look at intercooler for something along those lines. --Mdwyer (talk) 23:51, 17 January 2008 (UTC)

Can someone explain this to me?

Commutator (electric)? Seriously, that's the question, the article is too worthless to know enough to ask a more specific one! What does a commutator do? That 2nd picture on the right is very confusing too- it looks like the + and - ends of the battery are just connected up and something spins uselessly on top of the wires. Aah! --f f r o t h 21:37, 17 January 2008 (UTC)

• Just a mild observation; the article certainly doesn't look worthless to me. It looks well-written and informative. Tanthalas39 (talk) 21:58, 17 January 2008 (UTC)

The force exerted on a current in a magentic field acts in a particular direction relative to the current and the field (it's a right-hand rule, IIRC). So, if we had no commutator, and just a loop of wire connected to a battery between two magnets, then it would start turning, and then at some point the current would be going in the opposite direction than initially, and the torque would hence be in the opposite direction as well, meaning that instead of continuing to rotate, the wire would start turning backwards, and then you'd just have something that wobbled (or the wire would just turn until the torque was zero, and stay there).

With a commutator, the loop of wire isn't directly connected to the battery, but instead it makes contact with a pair of carbon brushes that complete the circuit. When the loop turns far enough, the two halves of the commutator lose contact with their respective brushes, and instead make contact with the other brush, thereby reversing the direction of current in the loop and ensuring the torque is in the same direction as before. Confusing Manifestation(Say hi!) 22:01, 17 January 2008 (UTC)

Oh, very neat! I didn't see that the purple loop was supposed to be attached to the spinning part.. I see how it works now. And I said it's worthless because a lot of the science articles (including that one) are written for people who already know everything about it.. they document knowledge, not teach it. So I guess that's a "use" but not the use I need it for :o --f f r o t h 00:14, 18 January 2008 (UTC)

Yeah- this is frequently part of an electric motor, as the article says. That thing that "spins uselessly" isn't useless at all- electric motors have many applications. Friday (talk) 22:55, 17 January 2008 (UTC)

I always thought it as a very crude way to simulate AC for an otherwise normal AC motor. --antilived^{T | C | G} 23:41, 17 January 2008 (UTC)

why dont we heat with rocks from hot places and cool with rocks from cool placse.

Why not make a very large thermos (vacuum flask) and put something, like rocks, with a high specific heat in it from a hot place, raise it to a blimp, and slowly, slowly, ship the blimp to where it's cold. This can take a long time, but no energy, if you're willing to wait long enough for it to drift over thanks to wind or whatever, or like sailboats, you can go against the current as well. Anyway, then you let the rocks down and heat with them until they're cold and repeat. Also, you get to cool with them where it's hot. The beginning of ice cubes history really did include shipping, so why dont we do this today, but with vacuum flasks? Also, if you use water you only have to lift it when the water is cold, since hot water could rise through a series of clever tubes. What do you think? —Preceding unsigned comment added by 212.51.122.20 (talk) 23:45, 17 January 2008 (UTC)

For a typical specific heat of say 0.9 J / (kg K), and a temperature difference of say 20 K, you have an energy density of 18 J / kg of rocks. Standard heating oil has an energy density closer to 40,000,000 J / kg. In other words, the amount of rocks required to displace normal fuel sources is simply impractical. Dragons flight (talk) 00:14, 18 January 2008 (UTC)

Waiting for blimps to sort of drift there is a terrible idea! Why not just harness the energy of the wind directly and use electric heating/cooling? --f f r o t h 00:17, 18 January 2008 (UTC)

I've read about buildings that do this by time-shifting rather than space-shifting. They let a big bunch of water freeze behind the building during the winter, then insulate it really well, then use the ice to cool that same building during the summertime. Presto! (But it obviously only works in areas that reliably get sustained hard freezes during the winter.) —Steve Summit (talk) 00:46, 18 January 2008 (UTC)

January 18

capillary force vaporizer

The capillary force vaporizer is new technology which offers many practical advantages for the military by burning the same fuel used to power Hum-Vees, trucks and aircraft. It was offered as a major breakthrough for backpackers as well and stoves based on the technology were supposed to become inexpensive and replace other types of stove that burned other fuels.

Today, however, stoves based on capillary force vaporizer technology are not only hard to find but expensive and it appears they are also being covered up. Is it possible that these stoves are so efficient and economical to use that they are being made scarce to discourage people who use gas stoves from converting to them, since we are supposed to be headed for renewable fissile fuels like gas and away from non-renewable fuels like oil? —Preceding unsigned comment added by 71.100.12.59 (talk) 01:52, 18 January 2008 (UTC)

No. (Well, okay, yes, it's possible. But it's vanishingly unlikely.) —Steve Summit (talk) 02:06, 18 January 2008 (UTC)

Okay then why can't I buy a CFV stove for my kitchen and a CFV furnace for my basement? —Preceding unsigned comment added by 71.100.12.59 (talk) 02:20, 18 January 2008 (UTC)

Why don't you call Vapore Inc. (of Richmond, CA) and ask them? —Steve Summit (talk) 02:26, 18 January 2008 (UTC)

Is the CFV concept patented or just the products they produce? Could someone implement the concept in another design without infringing on their patent? I belong to a ceramics class. —Preceding unsigned comment added by 71.100.12.59 (talk) 02:56, 18 January 2008 (UTC)