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February 21

Environmental Effect of Al Gore

Often, in criticism of Al Gore, I hear people say something along the lines of "Oh, he's such a hypocrite. He preaches about saving the environment while he himself flies around in his private jet."

Which led me to approach this quantitatively... say Al Gore traveled in a private jet from New York to Los Angeles and back. During the trip, he spoke to 500 people and convinced them to switch the light bulbs in their household to energy efficient light bulbs. Would the positive effect of people switching their light bulbs outweigh the pollution from the trip, or vice versa?

I'd like to see someone work this out. If they do, I ask that they state any assumptions they make. (How much power the jet uses, average household power usage, the change in wattage from the switch of light bulbs, etc.) 04:57, 21 February 2008 (UTC)

Allow enough time and certainly the power savings win out -- you're comparing a one-time cost to an ongoing improvement. This, however, addresses a straw man. It's not "Gore educates the world via private jet or not at all" but "Gore flies on a private jet or Gore flies a regular airliner". — Lomn 05:03, 21 February 2008 (UTC)[reply]

Well vaguely, let's see. A Gulfstream jet gets ~1.2 miles per gallon, and he's traveling of order 5000 miles round trip, so he uses ~4000 gallons of fuel. Jet fuel has an energy density of ~125 MJ / gal, so he used of order 500 GJ of energy. Assuming he convinces 500 people to reduce their energy consumption by 150 W each (equivalent to replacing ten 60-W bulbs with CFLs, assuming each bulb is run 8 hours a day on average) then that is a net savings of 75 kW. In which case, the energy cost of the plane trip will be recouped after 75 days. Environmental impact is generally proportional to energy cost modulo small multiples depending on how the energy is generated, so for the scenario you suggest, Al looks okay. Of course, it is probably pretty generous to assume Al gets 500 new converts every time he talks, and flying on a commercial airliner is still almost certainly more efficient regardless. Dragons flight (talk) 05:29, 21 February 2008 (UTC)[reply]

Incidentally, the best commercial airlines, fully loaded, can get as good as 30 miles per gallon per person, and hence use only about 5% of the energy per person as transporting a single person by small private jet. Dragons flight (talk) 05:35, 21 February 2008 (UTC)[reply]

Good point. I'll change the question slightly. Lets say a person (for the sake of bringing politics out of it, but thats probably too late) flies from New York to Los Angeles and back every week, and that they manage to get 500 people a month to switch. 05:15, 21 February 2008 (UTC) —Preceding unsigned comment added by Pakiprince7135 (talk • contribs)

This question seems irrelevant in all kinds of ways. First of all, the resources actually consumed by Gore, or any other individual human being, are negligible on a planetary scale. His jet could get 0.01 miles to the gallon and it wouldn't matter per se. Secondly, a celebrity like Gore doesn't primarily influence people by talking directly to them. Everything he does is symbolic. Politicians don't talk to individual voters just to get their votes, they do it to get the votes of people who see or hear about the conversation and start to think of the politician as a man of the people. If Gore acts hypocritically, or more to the point if he seems to act hypocritically, he'll lose followers. That's why he shouldn't waste jet fuel, not because the energy usage of the world's small population of celebrities makes such a difference in the grand scheme of things.

Also, a given amount of energy in jet fuel is worth more than an equal amount of energy in burning light bulbs, because petroleum is a much more precious resource than energy sources in general. -- BenRG (talk) 13:48, 21 February 2008 (UTC)[reply]

The entire discussion above is missing the critically important point that Al Gore always buys a carbon offset every time he flies, so that the CO₂ and other greenhouse gasses produced due to him flying are balanced out by CO₂ reduction measures elsewhere. Al Gore is very meticulously carbon neutral. MrRedact (talk) 19:10, 21 February 2008 (UTC)[reply]

Except that carbon offsets are bunk when used in that way. And can even be bunk otherwise too, if not carefully handled. 79.74.0.57 (talk) 00:30, 22 February 2008 (UTC)[reply]

Could you please explain why you think carbon offsets are bunk when used to offset air travel? I'm not asking to start an argument; I'd genuinely like to know. My girlfriend wants to take a trip to Machu Picchu that I'm not too keen on, but my global warming argument against going is getting shot down by the availability of carbon offsets. The whole tree planting variety of carbon offsets does seem of dubious value, since it seems to me like forest land is pretty much a fungible commodity -- if you plant and protect trees in one part of the planet, without reducing the demand for land, forests will just be destroyed in another part of the planet, instead. But it seems like it's hard to deny the value of more modern types of carbon offsets, like donating to a renewable energy project that wouldn't otherwise be developed, thereby not only reducing CO₂ production, but also reducing the consumption of our limited supply of fossil fuels. MrRedact (talk) 02:08, 22 February 2008 (UTC)[reply]

Dragon is pessimistic assuming that it saves only 15 watts to switch from a 60 watt incandescent to a comparable compact fluorescent. The CFL would use 13 to 15 watts, per GE [1] for a saving of 45 to 47 watts per bulb or at least 450 watts per person if he operates 10 bulbs. Edison (talk) 20:10, 21 February 2008 (UTC)[reply]

This depends on the climate lived in. If you're heating your house, switching to CFLs will require you to use more heating to keep the house at the same temperature, since there will be less heating from the bulbs. Add to this that if lightbulbs are switched off when you leave a room, an incandescent bulb only heats the rooms you are using when you are using them (unlike central heating). If you live in Florida, switching to CFLs probably makes sense and could indeed save many watts. If you live in a cooler climate, it's less clear cut. 79.74.0.57 (talk) 00:30, 22 February 2008 (UTC)[reply]

This has been mentioned before, but so far, no one has provided evidence that the waste heat generated by incandescent light bulbs actually contributes usefully to household heating. As I say everytime this comes up, it's always a bad idea to generate heat at the top, because hot air travels up. Indeed most of the heat doesn't just stay at the top, a fair amount of it stays fairly close to the light bulbs (since light bulbs aren't the best radiators or heat). In reality, I strongly suspect (but freely admit I have no evidence, but nor do the people who bring this up) incandescent bulbs contribution to household heating is minimal and significant less in proportion to what is generated. In other words, that waste heat really is waste heat. The simple reality is, well designed heaters are almost definitely a lot more efficient (if that's the right word) at heating a house then incandescent light bulbs so you will IMHO still save significantly with CFLs. I'm sure there must be some studies of this, i.e. comparing the energy usage of households in cold climates before and after switching to CFLs. Nil Einne (talk) 12:12, 22 February 2008 (UTC)[reply]

how can it be that "well designed heaters are almost definitely a lot more efficient" than light bulbs, when we are constantly being advised that incandescent bulbs are so inefficient at producing light, and all the energy that goes into an incandescent bulb comes out as either light, or heat? and the light, when absorbed, ends up as heat? that's 100% efficiency. the typical furnace wastes a lot of energy up the chimney, heating up the furnace itself which is typically in an uninhabited area where the heat is all wasted, heating up the ducts, pipes, etc. which are also typically wasting heat inside the walls or to the outer walls. all items which are significant enough to be addressed in modern, ultraefficient furnaces.

if the argument is that the amount of heat is not enough to make a difference, then it can't be enough to make a difference worth conserving. if it is worth conserving, then it's significant in terms of your total energy usage, which is greater than your heating energy usage, so by definition has to be significant there as well. Gzuckier (talk) 18:10, 26 February 2008 (UTC)[reply]

As I said, I'm assumming the lighting in your home is only on about 8 hours a day. Do you run all the lights in your house when you are away at work or asleep? Hence 450 / 3 is 150. Dragons flight (talk) 00:38, 22 February 2008 (UTC)[reply]

Redact, if Al Gore flew on an airliner, it would cost him less and he could buy more carbon offsets. The only reason you'd be able to use carbon offsets to justify something is if you could only afford them because of the action you took. This requires the environmentally friendly action to be more expensive, but it's almost always cheaper. — Daniel 23:21, 21 February 2008 (UTC)[reply]

Flying around and convincing people a few hundred at a time that global warming is a real problem and a result of human actions is a retail process, in a world with billions of energy users, whereas making an Academy Award winning documentary achieves the same goal in a wholesale manner. DVDs and video downloads do not require nearly as much jet fuel as the hypothesizes private jetting. But the years of lectures on the topic helped in developing the presentation and in gaining the degree of credibility needed to get the movie made and distributed. An Inconvenient Truth is the fourth highest grossing documentary film in the U.S. The companion book reached #1 on the NY Times nonfiction list. This followed a period when many politicians denied there was any global warming, or that anything needed to be done about it. Senator Jim Inhofe said "global warming is the greatest hoax ever perpetrated on the American people." What would be the monetary effects of doing less to prevent global warning or doing more to prevent it? "Stay home and don't lecture, to save airplane fuel", might be penny wise and pound foolish. Edison (talk) 06:04, 22 February 2008 (UTC)[reply]

Explain about the working of nMOS super buffers in VLSI?

Can you help me?

I am Joshy Karanath from India. Now I am studying B-Tech [ Electronics & Communication ] at Ihrd College Of Engineering, Poonjar , Kerala.

Now I need help from you. Please give me the explanation or tell me about the link from where I can get this information. The topcs are given below.

1. "process" in VLSI. (with figures)

2. Working of "Super Buffer" in VLSI. (Inverting type nMOS super buffer)

3. Detailed Explanation in "Second Order MOS device effects in VLSI" (all the five effects with figures)

4. Fabrication Process in "BiCMOS" in VLSI (With Figures)

Thanking you,

Joshy Karanath.

Apologies if this is rude of me, but I have reformatted your question to make it easier to read. No content has been changed, simply formatting and capitalization. I am sorry that I cannot help with your request, but I hope someone else can TheGreatZorko (talk) 11:29, 21 February 2008 (UTC)[reply]

Well, here's a link to start BiCMOS and here's another [[2]] to "Ion Implantation Process2 in VLSI, not sure about the figures.Richard Avery (talk) 12:31, 22 February 2008 (UTC)[reply]

Ion implantation is not specific to BiCMOS, although the concentrations of dopant are always going to vary on the exact process in use. Often times, a university-level class will pick one process and stick with that for the entire course.
A superbuffer is just a buffer with high current output (or high speed switching, which is often equivalent). The topology may consist of two nMOS inverters in series, (twice inverting preserves the original input), and the output stage may have a high drive strength with a push-pull output topology.
There are a lot of "second order" MOS channel effects. Take a look at channel length modulation and Drain Induced Barrier Lowering for a couple examples.
BiCMOS is almost always going to be used for a mixed signal ASIC, with digital and high frequency analog sharing the same die. The process will vary, but there are several established industrial and research processes.

Hope these links help, Nimur (talk) 22:02, 27 February 2008 (UTC)[reply]

Rabbit skeleton conservation

Which is the best way to conserve the skeleton of a dead rabbit so it does not disintegrate, while at the same time promoting flesh decay in the quickest and most hygienic manner? -- 83.56.190.69 (talk) 11:20, 21 February 2008 (UTC)[reply]

Would putting the corpse into a weak acid, and then transfering it to some sort of embalming fluid, such as formaldahyde work?

Out of curiosity what is this for? What is stopping you stripping the flesh and then simply preserving the skeleton? TheGreatZorko (talk) 11:32, 21 February 2008 (UTC)[reply]

Yes, I would be inclined to boil bunnikins if all you want are its bones. Of course you will need some way to reassemble the bones correctly and join them together. A museum might have some useful advice on how to do this.--Shantavira|^{feed me} 13:43, 21 February 2008 (UTC)[reply]

Note that this will smell pretty bad. Ventilate! --98.217.18.109 (talk) 13:50, 21 February 2008 (UTC)[reply]

Flesh eating ~~beatles~~ beetles are what commercial companies that do this kind of use according to "Dirty Jobs". Zrs 12 (talk) 14:30, 21 February 2008 (UTC)[reply]

Flesh eating beatles? I knew rock-and-roll was evil! DJ Clayworth (talk) 15:54, 21 February 2008 (UTC)[reply]

What, you've never heard of flesh eating Beatles ? :-) StuRat (talk) 13:54, 22 February 2008 (UTC)[reply]

Haha. Sorry, it was early. That better? Zrs 12 (talk) 23:11, 21 February 2008 (UTC)[reply]

Well, with AC/DC, rolling stones, and lead zepellins around, how could anyone doubt rock-and-roll was dangerous? 206.252.74.48 (talk) 16:07, 21 February 2008 (UTC)[reply]

19th century anatomists wouold sometimes place a skull or skull with some flesh attached in a perforated metal cage and sink it in a pond for a year or so to deflesh it. Museums clean bones of some animals with insects. Edison (talk) 20:02, 21 February 2008 (UTC)[reply]

I don't think we should be answering this question. He could be abusing animals for all we know. Malamockq (talk) 02:52, 22 February 2008 (UTC)[reply]

So could you. In fact, ... what made you bring it up? APL (talk) 05:57, 22 February 2008 (UTC)[reply]

ANTS ANTS ANTS

press machine

hi, pls tell us that which press machine(ie: 5 ton, 10 ton)should be used for cutting a CRC sheet of thickness of 0.5mm,which should not damage both tool&diePnengineers (talk) 11:34, 21 February 2008 (UTC)[reply]

CRC??--Shantavira|^{feed me} 12:56, 21 February 2008 (UTC)[reply]

CRC in this context is probably "Cold Reduced Coil steel". Also known as "cold rolled steel" (see cold rolling). It's not on the dab page, but probably should be. You would need more than 5 or 10 tons, maybe something like 30 tons, but it's years since I did anything like that and you really should contact a company that sells or hires such equipment; they would be able to advise you. Neıl ☎ 14:23, 21 February 2008 (UTC)[reply]

starch vs. sugar

Is there any real difference, from a nutrition or health standpoint, between consuming a given amount of calories from sugar vs. starch? ike9898 (talk) 14:58, 21 February 2008 (UTC)[reply]

Not really, no, not if you're talking calories. However, because starch is an enormous polysaccharide of glucose, and sugar (i'm assuming you mean table sugar) is a disaccharide of glucose and fructose, they will be digested into mono and disaccharide subunits for absorption in the small intestine in the same manner. Ultimately, the individual sugars will be metabolized differently when taken up by the cells, or the liver will end up processing them into glucose. Wisdom89 _{(_T / ^C)} 16:32, 21 February 2008 (UTC)[reply]

Probably most relevant to your question are the concepts of glycemic index and insulin index. These relate to how your body reacts to the consumption of equal amounts of different sugars (as far as changes in postprandial blood glucose/insulin levels are concerned, respectively.) Some people (including many doctors/dietitians) believe that there are important health benefits of a low glycemic/insuin index diet, including the South Beach diet and, to some extent, the Atkins diet, among others. (EhJJ)^TALK 16:41, 21 February 2008 (UTC)[reply]

The glycation activity of fructose (50% of sugar) appears to be much greater than that of glucose (100% of starch). Frankg (talk) 16:54, 21 February 2008 (UTC)[reply]

Aren't starch and sucrose both converted to glucose before being used by cells? Other than the greater tooth decay due to sugar and the higher glycemic index of sugar, what is the difference between consuming 200 calories a day of sugar or 200 calories a day of starch as paret of the diet, so far as long term health, weight gain, or the ability to do work? Edison (talk) 20:01, 21 February 2008 (UTC)[reply]

"Other than ... the higher glycemic index of sugar..." There's your answer. Hello diabetes! And other things. What did the Romans ever do for us? 79.74.0.57 (talk) 00:25, 22 February 2008 (UTC)[reply]

See Diabetes mellitus and Diabetic diet, especially the section on recommendations of the American Diabetes Association. Their diabetic diets do not forbid all consumption of sugars. Fruits and desserts with sugar content are often allowed in such diets. The grams of carbohydrate is what is typically tracked, and the carbohydrates may come from sugar or from starch. The quantity of carbs at a given meal is the factor tracked. 200 calories a day would be only 50 grams of carbohydrate, and spread across three meals and two or three snacks would not be a huge amount, especially in a typical 2000 calorie diet. The blood sugar rise after a meal is related to the total carbs consumed. Typically the insulin administered to a Type 1 diabetic for a given quantity of carbohydrate grams in the form of sugar is the same as for that number of carb grams in the form of starch. The glycemic index addresses how fast the blood sugar theoretically level rises and falls. Per Glycemic index, the starches white rice, baked potatos, and white bread have high glycemic indexes, higher than sucrose (table sugar). Edison (talk) 05:47, 22 February 2008 (UTC)[reply]

Isn't it surprising that a baked potato has a greater GI than sucrose? ike9898 (talk) 13:13, 22 February 2008 (UTC)[reply]

It is highly counterintuitive that eating a baked potato, white rice, or white bread amounting to say 200 calories would raise a diabetic's blood sugar faster than eating table sugar or candy totalling 200 calories. But that's what the table appears to say. Edison (talk) 20:41, 22 February 2008 (UTC)[reply]

Is the universe 100% logical and 100% consistent 100% of the time?

Is the Universe always logical and consistent, so that anything that FOLLOWS LOGICALLY from something else is in fact going to BE THAT WAY, with no exceptions, ever, in the history of the universe??? —Preceding unsigned comment added by 79.122.42.134 (talk) 16:20, 21 February 2008 (UTC)[reply]

No. I think what you're asking about is called Determinism, and it's how scientists used to think the world worked, but quantum theory isn't deterministic. AlmostReadytoFly (talk) 16:24, 21 February 2008 (UTC)[reply]

You may also want to read Deterministic system (philosophy) (EhJJ)^TALK 16:26, 21 February 2008 (UTC)[reply]

Surely determinism is the totally different position that everything that happens, happens because it follows logically (from earlier events and general laws) that it must happen? The answer to the OPs question is yes, but this is a property of logic, not the universe. In strict logical terms, no event's happening ever follows logically from any other set of events, and if something doesn't happen despite following from true facts and general laws, then the laws were false. Algebraist 16:39, 21 February 2008 (UTC)[reply]

I think the OP is looking at things a little too anthropocentrically. What seems logical and consistent to us might be very different to what is "truly" logical. While it ~~may seem like~~ is circular logic, everything that happens in the universe occurs due to natural laws and it is consistent because it's occurring in nature according to natural laws. If it didn't, one might assume some outside, supernatural force is acting upon it, or our own understanding of natural laws needs revision. -- MacAddct  1984 ^{(talk  contribs)} 18:45, 21 February 2008 (UTC)[reply]

Can you give me an example of something that MUST follow, but nevertheless empirically at least once in the history of the universe hasn't? I'm thinking of examples like: If you put drop three apples into an empty a basket there MUST be three, the Universe would have to be illogical or inconsistent to return a basket of 2 apples for no reason... Has stuff like that ever happened? (Like in dreams). —Preceding unsigned comment added by 79.122.42.134 (talk) 17:16, 21 February 2008 (UTC)[reply]

We could only answer whether each of us individually has ever had this experience, but can't answer if something like this has ever happened. There aren't enough observers to check that the universe has been consistent 100% of the time. Sancho 18:40, 21 February 2008 (UTC)[reply]

Essentially, let's say the universe has a set of rules called R, and we have an approximation of those rules called A (also known as Science). What you're asking is if R has ever contradicted itself (if the universe has broken its own rules). The problem, is we don't even know what R is. We can only tell when R contradicts A and then we adjust A to match our observed R. There are PLENTY of examples of R contradicting our (at the time) A (think relativity, quantum mechanics, virtual particles, etc.), where we had to change A. Theoretically, however, R always applies and can not contradict itself. (EhJJ)^TALK 19:04, 21 February 2008 (UTC)[reply]

That was a much more logical and elegant way of putting it than my ramblings! -- MacAddct  1984 ^{(talk  contribs)} 19:06, 21 February 2008 (UTC)[reply]

Speaking of apples in baskets, it reminds me of a physics joke: "The physics department is having a party at a professors house. Initially, there is no one in the house. Two professors enter the house (it's a small party). Afterward, three professors leave the party. Finally, one returns to the party. How many professors are in the house? None!" (2-3+1) = 0 This might seem illogical and contradictory, but that's how the universe works! (That is, from what I've been told. Maybe someone with more physics background can elaborate). (EhJJ)^TALK 19:15, 21 February 2008 (UTC)[reply]

Maybe an anti-professor entered the house. That would be logically indistinguishable from a professor leaving it. DJ Clayworth (talk) 20:12, 21 February 2008 (UTC)[reply]

If three walked out, then the initial observation that there was "no one in the house" was incorrect. I like the joke on the Mathematical joke page better. But this isn't about jokes, this is serious business, and the fact of the matter is that we know nothing. Who knows, maybe the universe isn't made up of quarks. Maybe everything is made up of universes, and our universe is a quark in another universe, ad infinitum. What is light is actually infinitely fast but it leaks into another dimension at a certain speed and gets instantly replaced by light from yet another dimension? What if time is actually tangible? How about liquid gravity? Multiverses! Stuff that exists only if people look at it! I'm not crazy! 206.252.74.48 (talk) 20:18, 21 February 2008 (UTC)[reply]

The other problem with determinism is that it isn't that something follows from something else, it's that everything follows from everything else - nothing in the universe is a truly closed system (except possibly the universe itself), and so even if you had all the rules at your disposal you would find it impossible to make 100% accurate predictions as that would require knowing the exact properties of everything in the universe at one time - even being accurate to a thousandth of a percent could become an error of a thousand percent in the long run, thanks to chaos theory. Confusing Manifestation(Say hi!) 22:24, 21 February 2008 (UTC)[reply]

Two problems: quantum theory is often nondeterministic. Read up if you are interested in details, but there are times that things seem to happen for no good reason and there is no way to predict exactly when they will happen. And it's not an issue with our knowledge of things; they seem to actually be indeterminate at a base physical level. Creepy, no? Einstein found the idea disgusting but it seems to be the case. Second problem: no non-trivial system of logic can be entirely complete and consistent, a priori. See Gödel's incompleteness theorems for the full proof, but it's pretty hard stuff to make sense of from the get-go. Nevertheless it seems to hold up well; to sum it up, as one webcomic artist I enjoy recently did: "Formulations of number theory: Complete, Consistent, Non-trivial. Choose two." --98.217.18.109 (talk) 22:56, 21 February 2008 (UTC)[reply]

Being controlled by quantum randomness is in a way worse than being controlled by predictable determinism...(to me personally) 199.76.153.227 (talk) 00:54, 22 February 2008 (UTC)[reply]

It's like everything is chaos so just pick the organised system or theory that comforts you best (as in the one that promises to cover the most ground of experience). Julia Rossi (talk) 09:30, 22 February 2008 (UTC)[reply]

At some point in the history of the universe you would have to agree that logic came into existence. Before the "big bang" what would be logical? There are 3 choices. 1) All of the nothing that existed prior to the introduction of space, time and matter acted verry illogical. The nothing decided to pack itself together so tight that it exploded and rearanged its nothing into hydrogen. You know the rest of the story. 2) We are a figment of the imagination of something and are not realy here. 3) We were created by God.- All of which realy go against logic. Some more than others. But as the gentleman said,"what is logical to us may be very differnt from what is truly logical." There is a day when eveyone finds out the diference. —Preceding unsigned comment added by 75.145.213.217 (talk) 23:48, 22 February 2008 (UTC)[reply]

I disagree that those are the only three choices. First of all, choice #1 is invalid since it refers to something that took place "before time". Without time there is no "before". Also, there is no really important difference between #2 and #3, and there is no evidence to support either version. Personally, I like the idea of an eternal multiverse, periodically "big banging" out new universes every billion years or so (something like this), but I admit that that's pretty much just speculation too. Still, there are probably dozens of other possibilities out there besides those. However, without evidence for any of these possibilities we're stepping out of the arena of science and into philosophy, where we're simply debating how many angels can dance on the head of a pin. Right now the best answer is simply, "We don't know." Now, some people try to equate "we don't know" with "therefore we know God/Allah/Jehovah/Buddha/Vishnu/Odin/Zeus/The Flying Spaghetti Monster/etc... did it", but not knowing something is not evidence for any conclusion. Don't let that keep you from trying to find out the answer though! :-) -- Hi Ev 11:38, 25 February 2008 (UTC)[reply]

Well said. Imagine Reason (talk) 23:46, 25 February 2008 (UTC)[reply]

Building a voltaic stack

I have been trying to build a voltaic stack for a science fair project. I have been using dime and pennies, all from after 2000, and blotter paper soaked in a vinegar-salt solution. I have used up to ten cells. I am connecting the stack by copper wire to an LED, but it will not light up. Does anyone know why or what I am doing wrong? —Preceding unsigned comment added by 70.253.160.19 (talk) 20:34, 21 February 2008 (UTC)[reply]

Do you have access to a voltmeter? The reason to ask is the following: there are two or three kinds of problems possible here.

Your stack might be working, a little, but unable to put out the amount of current required by the LED.
Your stack might be generating no voltage at all.
You might be wiring the LED backwards. The "D" in LED stands for diode; it will only conduct in one direction.

A voltmeter would let you see which it is. Once you know what kind of failure mode you have, you can start looking for likely causes. If it's the first kind, voltage but not enough current, you should look for high resistance in your circuit. Start by cleaning the coins well. If it's the second kind of problem, look for an unwanted current path. If your electrolyte (the vinegar-salt solution) allows current to flow along any path other than the series order of the cells, then you might have a short circuit. Finally, a voltmeter will allow you to detect which is the positive end of your stack, and confirm which way the LED will conduct. JohnAspinall (talk) 20:55, 21 February 2008 (UTC)[reply]

If we use D=dime, P=penny, and B=vinegar/salt blotter paper, does your stack look like this:

DBPDBPDBPDBP (4 stacked cells of Dime-Blotter-Penny each)

or like this:

DBPBDBPBDBPBDBPB (Dime-Blotter-Penny-Blotter-Dime etc, which will generate nothing except heat)

-SandyJax (talk) 21:18, 21 February 2008 (UTC)[reply]

If the voltmeter shows that you have sufficient voltage to light the LED, and you determine that the plus and minus ends of the battery are corrected to the correct terminals of the LED, then it still might not work because an LED requires a certain amount of current to light, and the tiny area of your coins may not produce sufficient current. A solution to this is to connect a capacitor across the battery (with the plus and minus terminals correctly connected) and allow a sufficient charge to build up with the LED disconnected. Then have a momentary pushbutton switch, or a knife switch, which is used to connect the battery/capacitor combination to the LED. The capacitor will be able to provide more of a surge of curent to momentarily flash the LED. Then open the switch to allow the charge to build up again. The capacitor should be an electrolytic one; I'm guessing of over 10 microfarads capacity and of a voltage rating higher than the battery can produce. The battery's current and voltage capability and the current and voltage requirements of the LED would enter into the design. If you provide more data, I'm sure folks here can provide more advice. You can leave the voltmeter connected across the battery/capacitor combination to monitor the buildup of voltage. You should not use so many pairs of metal discs in your battery that a hazardous voltage is built up: the LED might only need 3 to 4.5 volts- others may have some guideance for you here. See also LED circuit, Battery (electricity) and Capacitor. If the battery voltage with no load is much higher than the proper operating voltage of the LED, you might need to connect a current limiting resistor in series with the LED. You can avoid this by making sure the number of pairs of metal elements in the battery is high enough to light the LED but not too high. Older coins which were copper (or bronze)pennies and silver dimes may produce a higher voltage per pair. Edison (talk) 05:26, 22 February 2008 (UTC)[reply]

In response to the question, I built some voltaic cells with two coins separated by a double thickness of paper towel moistened with pickle juice, which contains both vinegar and salt. Note: the coins used in such experiments will be become corroded, discolord or damaged. With a modern dime and a modern penny, the open circuit voltage was .05 volts and the short circuit current was .08 milliamperes. With a 1958 wheat penny and a 1925 silver Mercury dime, the open circuit voltage was .15 volts and the short circuit current was .75 milliampere. With a new cent and the old silver Mercury dime the voltage was .14 volt and the short circuit current was 1.0 milliampere. With the 1958 wheat penny and the new dime, the open circuit voltage was .015 volt and the short circuit current was .05 milliampere. Then I tried aluminum foil and the silver dime. The open circuit voltage was .77 volt and the short circuit current was 36 milliamperes, which dropped in 30 seconds to 4 milliamperes. In later trials with new moistened paper in between, the max current was lower, around 10 milliamperes, but still promising for running an LED, if there were enough cells in the battery. With aluminum foil and a new penny, the open circuit voltage was .6 volt and the short circuit current wsa 6 milliamperes. In conclusion, a science fair project would do well to obtain adequate measuring instruments (a digital voltmeter is on the order of $30 at a hardware store) and to do some experimentation by trying metals at different places in the electromotive series, rather than just building something and voila it doesn't work. Get permission before experimenting with anything valuable. A worn coin worth little more than the value of the metal should be used rather than something with numismatic value which is in good condition. Why is the present dime so lousy in a battery with modern pennys? The modern Roosevelt dime is a copper center sandwiched between two outer layers of 75%copper, 25% nickel. The old Mercury dime is 90% silver, 10% copper. The modern cent (penny) is a 97.5% zinc center disk with 2.5% copper plating. The modern dime-modern cent battery is pretty close to copper and copper so far as what is on opposite sides of the blotter, and a Voltaic cell requires dissimilar metals. The 1958 wheat cent was an alloy of 95% copper, 5% zinc. Standard electrode potential (data page) gives electrode potentials for cells made of various metals. See Galvanic cell where it says more about how to calculate the expected voltage. See also Lemon battery. Edison (talk) 19:55, 22 February 2008 (UTC)[reply]

You might investigate using copper and zinc foil, plates, or sheet-metal (instead of coins). These plates are fairly cheap and available at hobby shops, metal shops, and some home-improvement warehouses. Nimur (talk) 22:09, 27 February 2008 (UTC)[reply]

Body wastes H2O?

Does the body not waste significant amounts of water, when we exhale? If I took a walk in the desert, surely I'd fancy to not let go of all the water in my body, but rather keep it circulating. Why is it treated like a waste product? 81.93.102.185 (talk) 20:41, 21 February 2008 (UTC)[reply]

The values for obligate water loss in humans are fairly well established. The minimum insensible water loss is about 800 ml per day; of this, about 400 ml per day are lost via evaporation from the skin, and about 400 ml per day are lost via expired air. These minimum values would obviously be exceeded in the heat of the desert in the midst of exertion.

Humans are not particularly well-adapted for desert life (nor is there any particular reason we should be, as by and large we don't live in deserts). The kangaroo rat does a much better job, both in terms of concentrating its urine, and in terms of reducing water loss through the lungs. :). - Nunh-huh 21:32, 21 February 2008 (UTC)[reply]

Bleh, bad statement you made. Yes, we aren't well suited for deserts. Humans aren't well suited for a lot of enviroments, especially cold enviroments. But don't say there's no reason to be. Humans live all around the world. Not just in your neighborhood. 64.236.121.129 (talk) 17:12, 25 February 2008 (UTC)[reply]

Humans evolved in tropical Africa, which was wetter at the time than it is now. 98.199.17.94 (talk) 02:09, 22 February 2008 (UTC)[reply]

Camels, which are better adapted to desert life than we are, have a convoluted moisture-exchange organ in their noses to extract water from the exhaled air, and add it back to the inhaled air. --mglg_(talk) 04:38, 22 February 2008 (UTC)[reply]

Note that water could be preserved, through something like the stillsuits featured in the book Dune (novel). They covered the skin and the wearer exhaled through a tube which led to a device that extracted the moisture. (In the movie version the suits didn't cover the faces, simply because people don't want to watch a movie where everyone looks alike with covered faces.) Why don't we really use such a device on Earth ? Unlike Arrakis (the desert planet in Dune), water is plentiful on Earth, so the need hasn't arisen. Such a suit would be expensive to make (something like the cost of a diving dry suit with full SCUBA gear), and it's less expensive to just bring enough water with you when you go into the desert. One issue a still suit would have is that exhaled breath is full of bacteria, so the reclaimed moisture would need to be sterilized or the bacteria would grow in the collected water. As for reclaiming moisture from urine and solid waste, the suit wouldn't need to do this, as those wastes could be collected and you could have their water extracted using a device elsewhere. StuRat (talk) 13:35, 22 February 2008 (UTC)[reply]

A stillsuit would be very challanging to make and probablly cost a lot more than diving gear. Liquid that comes out of the body would need to be collected, cooled (since one of the main reasons the human body sheds water is to shed heat), purified, steralised and then fed back to the body somehow and for it to be worthwhile you would need to do all this including providing a power source for it in less weight than it took to just bring water with you. Plugwash (talk) 13:44, 22 February 2008 (UTC)[reply]

In Dune, the suits ran off body motion. I can possibly buy this if they just removed water from breathing and sweat, but not if they processed urine and feces, too. The sterilization for breath and sweat could be as simple as dropping the water through an activated charcoal filter, adding something like the disinfection tablets campers sometimes add to river water to make it safe, then dropping the water into storage tanks in the legs. I wasn't including the cooling function. There are dry, cold deserts, like the Gobi Desert, so the "moisture-retention only" model would have some use, although I agree that the expense would make it cheaper to just bring all the water you need with you, instead. StuRat (talk) 18:56, 22 February 2008 (UTC)[reply]

A minor quibble—normally exhaled breath isn't 'full of bacteria'. The vapour pressure of a bacterium (or of any other microorganism or pathogen) is essentially zero; bacteria can't 'evaporate' into the exhaled airstream. The air exhaled by a healthy individual will be essentially free of bacteria, and what little there is will be normal and relatively non-toxic mouth flora. A sick individual coughing and sneezing, or a healthy individual breathing raggedly and/or particularly violently will disturb droplets of mucous in the throat, nose, and mouth; this can aerosolize bacteria that may be present and will generate some bacterial load in exhaled air.

Of course, all the surfaces that come intact with the exhaled breath will be warm and moist, and thus excellent sites for bacterial growth. Even a small amount of input bacteria would very rapidly tend to become a lot of bacteria. I agree that keeping such a system clean would represent a significant design challenge. TenOfAllTrades(talk) 19:38, 22 February 2008 (UTC)[reply]

February 22

What else is there?

As a non-physics type reflecting on the "What exactly is a magnetic field" thread of Feb 15, when a person asks whether something's animal, vegetable or mineral, what else is there? How close is energy (like a force field) to being matter – can you say that? Julia Rossi (talk) 04:21, 22 February 2008 (UTC)[reply]

It depends on one's definition of mineral. If you're using mineral to mean "anything that isn't plant or animal", it's sort of lost all meaning. A true mineral is a solid substance "formed through geological processes". A computer isn't animal, vegetable, or mineral. There are also non-physical things such as thoughts, emotions, dreams, etc... -- MacAddct  1984 ^{(talk  contribs)} 05:59, 22 February 2008 (UTC)[reply]

Thoughts, emotions, and dreams are sort of physical, in that they are an abstraction that only exist as a physical represention, as an activation pattern of neurons, and/or a pattern of efficacy of synapses. Neurons and synapses are of course physical. It's very much like the movie Blade Runner is an abstraction that sort of isn't physical, but all of its representations are physical, such as a pattern consisting of the presence or absence of pits on a polycarbonate disk (a DVD), or a pattern consisting of the presence or absence of various pigments on a strip of acetate (film).

A physicist wouldn't look at everything that exists physically as being animal, vegetable, or mineral. Rather, everything that exists physically ultimately consists of elementary particles, which includes matter (quarks and leptons) and energy in the form of gauge bosons. MrRedact (talk) 08:37, 22 February 2008 (UTC)[reply]

Nice pick of Bladerunner in this context, by the way. Emotions seem more like energy that results from other things being activated, say by a thought, is that what's meant MacAddct?. And MrRedact, are you saying everything is comprised of particles (of one kind or another) of matter? Then does the question, animal, vegetable or mineral need to be upgraded to – well, you name it, what would you say? Is it molar, molecular or action? The article says "all force carrier particles are bosons" can we take it that forces are still separate but show up through the particles and that it's not the forces, but the particles that could give the impression that a force field (with its pressure) seems almost material? (Is the sound that knocks out a candle flame say, a proper example?) Julia Rossi (talk) 09:13, 22 February 2008 (UTC)[reply]

That's sort of what I mean. Things that happen in the brain, while they are all a result of electrical activity, we still recognize them as unique properties (e.g., separating dreams from thought). But when you boil everything down, as far as we know, everything is made up of the particles that MrRedact mentioned. -- MacAddct  1984 ^{(talk  contribs)} 14:14, 22 February 2008 (UTC)[reply]

I didn't realise that the particle of matter extended so far, even to their effects and things between them. Thanks so much, it's engrossing stuff. Julia Rossi (talk) 23:32, 22 February 2008 (UTC)[reply]

Belated bruise

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

This may not seem like asking for medical advice to you, but it sure seems like it to me. You should ask your doctor as to whether that's normal, and what if anything you should do about it. MrRedact (talk) 07:47, 22 February 2008 (UTC)[reply]

It sent me to the Bruise article which threw some light on the nature of bruising and its indications are as per above and get it straight from the medico mouth - should be very informative. Julia Rossi (talk) 09:19, 22 February 2008 (UTC)[reply]

3600rpm 1000 HP electrical motor. Need bibliography. Vibration

I have three of theese motors installed. one of them has vibration values that jump up and down. I've heard this is normal and that this is NOT normal. Which is true. How do I justify? —Preceding unsigned comment added by Arielerosa (talk • contribs) 05:11, 22 February 2008 (UTC)[reply]

This is not a place to obtain professional advice related to safety or possible economic loss. Have you brought this concern to the manufacturer or vendor? You might wish to consult a qualified electrical engineer who is knowledgable about the vibration expected from motors. Excess vibration, of course, can cause bearing damage and further deterioration. Edison (talk) 19:02, 22 February 2008 (UTC)[reply]

Power factor in electric circuit

How can be use a capacitor to improve the power factor of a parallel ac circuit? —Preceding unsigned comment added by Meetpramendra (talk • contribs) 05:34, 22 February 2008 (UTC)[reply]

In an AC circuit with resistance and inductance, such as a motor, the current waveform lags behind the voltage waveform. The total current is larger than necessary, producing lower voltage at the motor terminals than if the current and voltage were in phase. A properly sized capacitor can correct the power factor, improving the voltage, and reducing the current which must be supplied by transformers and service conductors. For a more thorough discussion, see Power factor correction. Edison (talk) 07:11, 22 February 2008 (UTC)[reply]

The way I understand power factor is very simple. When power factor less than one occurs, it means extra power is needed but those extra power (technically electrons) is not being used to do useful work instead they bounce back and forth between the load (aka electric motor) and the generating station (aka power plant). In an ideal world, this does not matter because the transmission lines have zero resistance. But in the real world, transmission lines have non-zero resistance and it means power is being lost moving back and forth between the load and the generating station. Since the customer does not pay for power loss on the transmission lines. The electrical companies FORCE the customer to "tune" the power factor of a load to one. 122.107.226.136 (talk) 22:34, 22 February 2008 (UTC)[reply]

Well, "close" to 1, anyway. Nimur (talk) 22:12, 27 February 2008 (UTC)[reply]

Old voice recordings

When I hear very old recordings of American voices (early 20th cen.), they sound distinctly different from modern voices. I don't know how to describe it other than to say they sound more "nasal" and higher pitched. I'd like to know if this is due to the recording technology of the era, or a true change in the way Americans speak. ike9898 (talk) 13:05, 22 February 2008 (UTC)[reply]

It's changes in the technology. Specifically, older recording methods did not record much bass, so all you hear is the treble component. If you adjust your radio to all treble and no bass, modern voices will sound similar. Unfortunately, it isn't reversible, so adjusting the radio to all bass and no treble won't do much to improve an old voice recording, as there isn't enough bass there to begin with for this bass magnification to do much good. StuRat (talk) 13:19, 22 February 2008 (UTC)[reply]

Surely part of it must also be that people really did speak differently then. Maybe not so much their voice per say, but their form of diction and register might be significantly different from what it is today. -- MacAddct  1984 ^{(talk  contribs)} 14:21, 22 February 2008 (UTC)[reply]

I highly doubt that's a contributing factor - It's audio technology advances - Reel tapes for recording back then as opposed to digital today. Wisdom89 _{(_T / ^C)} 17:39, 22 February 2008 (UTC)[reply]

Analog reel-to-reel is capable of capturing speech with as high of a fidelity or even better than current digital methods. So, whatever the technology change was that improved vocal capture, it was something earlier than the use of analog reel-to-reel tape. StuRat (talk) 01:44, 23 February 2008 (UTC)[reply]

Could it have been the introduction electrical recording as opposed to purely acoustic recording? Sound_recording_and_reproduction#4 —Preceding unsigned comment added by 79.76.211.150 (talk) 20:18, 24 February 2008 (UTC)[reply]

Wasn't the sound the OP describes usually recorded onto wax cylinders and early phonograph records? 206.252.74.48 (talk) 18:11, 22 February 2008 (UTC)[reply]

I believe so yes, dating back to the 1940's and 50's? Wisdom89 _{(_T / ^C)} 18:15, 22 February 2008 (UTC)[reply]

There are changes in the accents within a population over time. I have listened to many recordings from the 1890's on and recordings of radio programs and news broadcasts as well as sound movies (sound on film) from the late 1920's on. Some speakers engaged in a style of "elocution" to make themselves heard without public address systems which would sound odd and contrived today. Many singers did in the 1920's and earlier in fact use a degree of nasality which sounds wierd today. The switch in the 1920's from acoustic recording to electrical recording improved the fidelity without really changing the nasal quality. It is not just the greater audio fidelity of today's recordings. I have listened to a cross section of Americans recorded in fairly high fidelity by a radio station on the day the end of World War 2 was announced in 1945, and their accents departed from what I would expect to hear today: more regional variation. The speech sounded "dated" and quaint. There has been a levelling of speech in America, with fewer "hick" or "rube" accents and fewer plummy accents indicating high socioeconomic status. Broadcast media is likely a big factor in producing more standardized general American speech. Edison (talk) 18:54, 22 February 2008 (UTC)[reply]

Actually, studies have shown that radio, television, etc have no effect on a speaker's or speech community's accent. This is related to the fact that children don't learn to speak from such devices. There have been changes in pronunciation of English since the 1890s, but the "leveling" of which you speak, if even present, would be pretty minor and due more to people moving about the country. What Ike9898 is asking about has much more to do with the technology than diachronic change. — Æµ§œš¹ _{[aɪm ˈfɻɛ̃ⁿdˡi]} 01:24, 23 February 2008 (UTC)[reply]

Also note that the lack of bass in early recordings effects sounds other than just voices, such as music. StuRat (talk) 01:49, 23 February 2008 (UTC)[reply]

I am not that impressed by studies which "prove" a negative such as is claimed above. "Studies" have also shown that an individual's speech is not frozen when he learns from his parents how to speak. Thus broadcast influences could well affect speech. One multi-decade study in Philadelphia noted speech changes in the same individuals over time. There was also the "great vowel shift" centuries ago in which the pronunciation of English changed, with "mice" having the vowel sound change from the older "mees" to the present pronunciation, with one writer at the time marvelling about how the language had changed since he was a youth, his own pronunciation included. In recordings from the 1930's and 1940's, for example, I note more speaker in the U.S. pronouncing "r" sounds in a more British "ah" way. Bass/treble balance has no effect on such linguistic variation. Edison (talk) 20:51, 23 February 2008 (UTC)[reply]

Ahem, mouse was pronounced like moose, not mees. This change did not occur over a single generation. No one is arguing that language doesn't change over time, and of course we can spot phonetic differences from recordings a hundred years ago. — Æµ§œš¹ _{[aɪm ˈfɻɛ̃ⁿdˡi]} 23:45, 23 February 2008 (UTC)[reply]

You are confusing the pronunciation shift of "moose" to "mouse" and "meese" to mice." And as I recall, it happened in the life of publisher William Caxton. See The Learning Company's course on the history of the English language, or see [3] and [4]. Edison (talk) 05:16, 26 February 2008 (UTC)[reply]

I would have to agree it sounds bizzare to suggest broadcast media could not affect the way people speak because it's not how they learn to speak. Accents are not static. Immigration would seem to disprove this claim immedietly. Most immigrants (especially those who emmigrate in their early 20s or 30) will, while retaining an accent with some charateristics of where they grew up, also have changes in their accent based on where they now live. Indeed in some cases their accent may be similar enough to a 'native's' accent that it will be indistinguisable to all but the extremely trained ear. These obviously depend greatly on the level of interaction the person has with native speakers. And I'm talking about immigrants who grew up speaking English (or whatever language were referring to). For that matter, people can learn multiple accents whether conciously (as actors/actresses, call centre workers, etc show)or subconciously. Speaking of immigrants again, many may be able to speak with an accent more similar to their original accent if they desire and may for example, even do it fairly subconciously if they go back to their native country for a holiday or whatever. This obviously doesn't prove people learn from broadcast media, but it does suggest it's ludicrious to suggest only what people learn in childhood matters. Nil Einne (talk) 08:00, 26 February 2008 (UTC)[reply]

Modem

Sir, I want to know wat a modem in engineering sense with some examples and illustrations its use etc... Thanku —Preceding unsigned comment added by 117.196.162.187 (talk) 14:28, 22 February 2008 (UTC)[reply]

Have you reviewed our article on modems? Also, please don't type in ALL CAPS; not only is it more difficult to read, it is seen as YELLING and isn't considered polite. TenOfAllTrades(talk) 14:40, 22 February 2008 (UTC)[reply]

I would also recommend not to yell yourself. Don't break rules to illustrate a point. 64.236.121.129 (talk) 17:14, 25 February 2008 (UTC)[reply]

Electromagnet

We were doing an experiment with electromagnets using a coil of wire, an iron nail, a 9V battery, and a paperclip. When we created the electromagnet by generating a current through the wire, it picked up the paper clip, of course. But, after we removed the current, the nail acted as a working magnet. What has happened here? Nick (talk) 16:02, 22 February 2008 (UTC)nicholassayshi[reply]

Are you sure the nail wasn't steel? AlmostReadytoFly (talk) 16:05, 22 February 2008 (UTC)[reply]

The difference is not between iron and steel, but between hard and soft. A soft iron core will lose magnetism as soon as the electricity is switched off, a hard iron core will retain some magnetism. (If someone more knowledgeable can write helpful things for those links to point to, that would be lovely). A soft iron core, as well as only being magnetic when the current is flowing, will provide a stronger magnet than a hard iron core. If I recall from my school days, the difference between them is down to how quickly they are cooled when being made. I think soft iron is the one that is slowly cooled, taking hours or even days, giving a different structure to hard iron which is cooled much more swiftly. Unless the manufacturer is making the iron for an electromagnet, they are probably going to make hard iron as it is easier and cheaper. Skittle (talk) 17:49, 22 February 2008 (UTC)[reply]

What happened was ferromagnetism, which is the phenomenon by which materials, such as iron, in an external magnetic field become magnetized and remain magnetized for a period after the material is no longer in the field. MrRedact (talk) 17:52, 22 February 2008 (UTC)[reply]

If you had measured the actual strength of the magnet's pull, you would probably have found that the pull with current off was way lower than with current on. Even an iron ("soft" ferromagnetic material) nail can retain a bit of the magnetization. A piece of steel{"hard" ferromagnetic material) would have retained a much higher degree of magnetization. Lifting one paperclip may not have been a severe enough test of the magnet's strength. Steel has greater Retentivity than iron. Edison (talk) 18:46, 22 February 2008 (UTC)[reply]

Not wishing to quibble, but you seem to be suggesting the difference is between iron being 'soft' and steel being 'hard'. I'm really pretty sure that you can get soft iron and hard iron, and that good soft iron retains almost no / no magnetism while cheap hard iron retains a noticeable magnetism. While I have no doubt that steel has a higher retentivity than iron, the retentivity of iron is highly dependent on its structure which is, in turn, highly dependent on the cooling conditions. I seem to recall doing an entire module on this. Skittle (talk) 00:07, 23 February 2008 (UTC)[reply]

Paper Clip Capacitor

A long time ago I had a physics teacher who had an old hand crank generator in their room to show how magnets can generate electricity. One day me and some fellow students where playing around with it and one of them took a paperclip and placed it on the two contacts (where it stuck due to magnetism) and I started cranking the generator like crazy. Nothing happened (some of my peers thought the clip would melt, which I thought was ridiculous) so I reached for the clip to remove it so we can attach something else. As soon as I touched it I was literally thrown back so hard that I (in a spinning office chair) hit the opposite wall. Obviously I was electricuted, and I've experienced a shock of almost the same strength with a vacuum cleaner. I am wondering how a paperclip could store so much charge, or how it could store charge at all. This generator can barely make a small light bulb glow and yet it could throw me across a room and even temporarily paralize the left side of my body for a minute (something that I should have told someone, maybe. I'm fine 4 years later, so I doubt it was a problem). How is this possible? 206.252.74.48 (talk) 16:45, 22 February 2008 (UTC)[reply]

A capacitor needs two things, an electrical conductor to hold the charge, in this case the metal paper clip, and an electrical insulator to prevent discharge. Air makes for a minimal insulator, allowing the conductor to hold the charge for a few minutes as it slowly bleeds off. The clip might also have had a coating on it which worked as an electrical insulator. Contact with a better conductor, in this case you, allowed the paper clip to rapidly discharge. I must comment that touching the clip immediately with a bare hand was not at all a wise thing to do. Even if it hadn't retained the charge, it could have been hot enough to burn you severely, this could have happened if the clip had more electrical resistance or only had intermittent contact with the generator (you would get sparks in this case). Also, the term "electrocuted" means killed due to an electrical shock, and this obviously was not the case here. StuRat (talk) 18:00, 22 February 2008 (UTC)[reply]

I've never been one to use common sense. I've been injured countless amounts of times in high school, and this just happens to be a notable one. Curiously, the paper clip wasn't hot when someone else took it off. Maybe they just ignored the pain, such is the strength of conformity. 206.252.74.48 (talk) 18:09, 22 February 2008 (UTC)[reply]

If this was a standard steel paper clip, directly touching both contacts, I wouldn't expect it to get very hot from the amount of current produced by a hand generator, as steel has a fairly low electrical resistance. The electrical charge would have been largely dissipated (into you) by the time your friend touched it. Maybe it's time to use a bit more common sense before you get seriously injured or killed. StuRat (talk) 18:20, 22 February 2008 (UTC)[reply]

While there was likely some capacitance somewhere in the system, the paperclip definitely wasn't it. The capacitance of a few centimeters of wire (insulated or in air) is going to be somewhere in the very approximate neighbourhood – give or take a couple orders of magnitude – of one picofarad. Even charged to an utterly implausible potential, the paperclip isn't going to store an appreciable amount of energy. (Consider—has anyone ever gotten an electric shock from touching the exposed terminals of an isolated extension cord immediately after unplugging it from the receptacle? Lengths of wire are pathetic capacitors.) TenOfAllTrades(talk) 18:25, 22 February 2008 (UTC)[reply]

I would argue that the wires in an extension cord could hold a substantial charge for a short period of time, but that normal use of an extension cord doesn't cause that to happen. (The charge flows in one end and out the other, and none is retained.) I'm not sure if this retention of charge in electrical conductors qualifies under the definition of a capacitor, however. StuRat (talk) 18:38, 22 February 2008 (UTC)[reply]

You could argue that, but you'd be mistaken—electricity can be a bit counterintuitive sometimes. The self-capacitance of modest lengths of wire is almost trivially tiny. (Coaxial cable typically has a capacitance of about 100 pF per meter[5]; the capacitance of a paperclip wire will be less than that.) For the record, capacitance is defined as the amount of charge stored divided by the electrical potential: C = Q/V. You just can't cram many surplus charges into a wire at any reasonable potential, so it has a very low capacitance. TenOfAllTrades(talk) 19:26, 22 February 2008 (UTC)[reply]

Actually, electrocuted means killed or harmed by electric shock. -80.229.152.246 (talk) 18:14, 22 February 2008 (UTC)[reply]

Actually actually, electrocution means being killed by electric shock or damage due to electric charge [6] —Preceding unsigned comment added by 79.76.197.6 (talk) 00:09, 23 February 2008 (UTC)[reply]

I was thinking about that, thanks for clearing it up. So what is the term for what happened to me? Just "shocked"? 206.252.74.48 (talk) 18:19, 22 February 2008 (UTC)[reply]

Yes, or "electrified". StuRat (talk) 18:22, 22 February 2008 (UTC)[reply]

Whether or not "electrocuted" implies being killed is one of those things that varies according to who uses the word, or possibly by country. Anyway, we've cleared it up now. --Anon, 18:24 UTC, February 22, 2008.

Some dictionaries only say kill, others include injury. It's clear, however, that it originally meant death only, as the origin of the word is "electro-execution", referring to execution using the electric chair: [7]. I therefore consider the "injury" usage to be a modern misunderstanding of the word. Unfortunately, this misunderstanding is widespread enough to have now gathered some level of acceptance. StuRat (talk) 18:31, 22 February 2008 (UTC)[reply]

The term "Westinghoused" just never caught on for electrocution. I can't rule out the possibility, from your description, that the generator had a capacitor somewhere in the circuit hooked to it at the time you got the shock. Of course, if the generator were still being cranked and you touched two fingers across the terminals, even an old wall telephone magneto could generate sufficient current and voltage to produce a painful shock that you would long remember. Was it a telephone magneto or some other sort of generator? I have used a hand cranked resistance tester called a "Megger" which produced 1000 volts DC. A Wall phone magneto would have produced probably tens of milliamps at around a hundred volts max, depending on the speed it was cranked. If a capacitor were connected to such a phone magneto,or a Megger, it could store enough charge to produce a fatal electrocution. I would not expect an accidental capacitor in the form of a paperclip to store much electricity at the voltages produced by a hand cranked generator. If it were an extremely high voltage static generator, such as a Van de Graaf or Wimshurst machine, then a capacitor such as a plastic film container filled with water could act as a Leyden Jar or capacitor and store a painful or dangerous charge. Edison (talk) 18:38, 22 February 2008 (UTC)[reply]

From what I recall, the generator was a bunch of "U"-shaped magnets (each about the size of a horseshoe) attached to a board, with a length of metal covered in copper wire suspended inside it that was attached to the crank. The two terminals were made out of screws, and the gear assembly and the crank were taken from an old pencil sharpener. It was basically made out of scratch sometime in the 1950s. Also, no one was cranking the generator at the time of contact. 206.252.74.48 (talk) 19:22, 22 February 2008 (UTC)[reply]

The voltage it produced should have dropped to zero as soon as it stopped spinning unless there was a sizeable capacitor attached. If it was used to power an electromagnet, it was probably not designed to create extremely high voltage at extremely low current like the Megger. There might have been a rectifier to supply DC to the electromagnet, unless it was a DC generator with a built in comutator. I can't see how a paper clip connected to such a generator could store enough charge to zap you. Even if a capacitor were solidly connected across the output terminals, its charge should have drained away through the fairly low resistance of the winding. Some wall phone magnetos disconnected the winding from the output terminals as soon as you stopped cranking, to prevent the winding draining away the voice current when you talked. Some old wall phones also had capacitors to help operate the bells on the front. All the elements are there for there to have been a capacitor charged by the spinning armature and disconnected and waiting to zap you, if the thing was taken from an old wall phone. See telephone magneto and another telephone magneto. See wall phone for a diagram including the capacitor or condensor. Edison (talk) 20:34, 22 February 2008 (UTC)[reply]

I don't think the electricity threw you across the room, it was probably your muscles seizing + numbness/paralysis that caused the illusion of being "thrown back" :D\=< (talk) 23:01, 22 February 2008 (UTC)[reply]

What do you mean by "small light bulb"? --Milkbreath (talk) 23:10, 22 February 2008 (UTC)[reply]

A telephone magneto will light a 7.5 watt 120 volt bulb, but not (in my experience 40 watts or larger. Just saying. Edison (talk) 23:51, 22 February 2008 (UTC)[reply]

the answer here is clearly nothing to do with capacitance as many have pointed out. It is more likely the energy stored by inductance in the generator coils. The paperclip is shortcircuiting the output, but steel is not that good a conductor so it will take time for the magentic energy stored in the coil to drain through the resistance of the paperclip. Removing the paperclip breaks the circuit, but inductors are not able to instantly change the current flowing through them. The terminal voltage will consequently instantly rise to a potential that can sustain (for an instant) the previous current. As you are an even poorer conductor than the paperclip, this probably required a rather substantial voltage for a short period, then the current would rapidly decay. Conversly, if the paperclip had not been there, then there would have been no output current and hence little energy stored in the coils, and the terminal voltage would decay much faster, making it safe to touch immediately. I am astounded by the number of different dangerous things that can be done with a paperclip. Somebody should write an article on it. SpinningSpark 16:34, 23 February 2008 (UTC)[reply]

Yes, the inductance explanation seems much more plausible than the capacitance explanation. However, the resistance of the paper clip is negligible in this problem. The resistivity of steel is greater than some other metals, but it isn’t that high. Depending on the alloy, it’s around 10^-7 to 10^-6 Ωm.[8] The resistance of a paper clip is just a very small fraction of an ohm. I tried measuring the resistance of a paperclip using an ohmmeter, and I couldn’t detect a value different from zero. What’s really limiting the current in this circuit is the resistance of the coils, not the resistance of the paperclip. MrRedact (talk) 18:21, 23 February 2008 (UTC)[reply]

No, no, no. Inductance doesn't store anything. Inductors take energy from the current and put it into a field around them. The instant the current stops, the field collapses. It takes no time at all, almost literally. A coil will ring as the collapsing field induces a cuurent which creates a field which collapses, etc., but that, too, happens in an instant. The only way I can think of for our boy to be telling the truth is if there was a great big capacitor across the terminals, the paperclip wasn't making contact between the two terminals for whatever reason (paint?), and he got across the cap. This is supposing that the generator could produce enough EMF to jolt a person. I got 300V from a big filter cap hand-to-hand one time, and I can confirm that it will light up your life. --Milkbreath (talk) 20:11, 23 February 2008 (UTC)[reply]

I do not expect that the current would continue through the winding of the magneto for more than milliseconds after the thing stopped turning. If it were being cranked with a paperclip shorting it, there might indeed be a very high voltage when the circuit was broken, perhaps hundreds of volts, due to self-induction, if the inductance of the winding was high enough. Once it has stopped, I would not expect a shock from breaking the circuit. Edison (talk) 20:22, 23 February 2008 (UTC)[reply]

As of the instant the generator was stopped, the circuit can basically be modeled as a closed loop consisting of an inductor (representing the inductance of the coil) in series with a resistor (representing the resistance of the coil). I think any stray capacitances involved are going to be negligible. There wouldn’t be any ringing in this idealized circuit, because ringing requires a circuit governed by a second-order differential equation, and this simple RL circuit is only first order. What will happen is that after the generator is stopped, the current in the circuit will decay exponentially, with a characteristic time of L/R. So for example, if the coil has an inductance of 1H and a resistance of 1Ω, then a second after the generator was stopped, the circuit will still have a current going through it that’s e^-1 = 0.368 times as big as the current in the circuit as of the instant the generator was stopped. I’m guessing the coil probably has an inductance of less than 1H, and a resistance of greater than1Ω, so the OP would have less than a second after stopping the generator to break the circuit, in order to get a jolt that’s close to the amount of current that was in the circuit originally. However, the currents involved are going to quite large (albeit at initially quite low voltages), due to the generator being shorted out. MrRedact (talk) 21:04, 23 February 2008 (UTC)[reply]

I think it’s time to go numeric, in order to get an order-of-magnitude estimate to see if the inductance hypothesis is plausible. It sounds like the generator can only produce a relatively small amount of power, like in the ballpark of 10 watts. My guess is the coil has a resistance of more than an ohm, but it only consists of wire, so its resistance can’t be that high; let’s call it 5Ω. From the equation P=I²R, that means that the shorted-out generator was initially producing about 1.4A of current. The two coils on this little inductor[9], that’s only a fraction of an inch big, total close to 0.1H, so an estimate of 1H for the generator coil, that’s presumably much bigger, seems like a not unreasonable estimate of the generator coil’s inductance. For the OP to have considered the generator to have for sure have been stopped, there must have been a time in between when the generator was stopped and when the circuit was broken that’s not unreasonably small on a human time scale; let’s call it half a second. The amount of current that the OP would have received when he opened the circuit is I₀e^{-t R / L}, which, plugging in the above values, comes to about 0.1A. Given that a shock of 0.1A can kill you, it seems quite plausible that the inductance explanation is sufficient to explain how the OP could have gotten one heck of a jolt under the circumstances described. MrRedact (talk) 23:11, 23 February 2008 (UTC)[reply]

By the way, when I said that “the inductance explanation seems much more plausible than the capacitance explanation,” I was in that sentence only referring to the very implausible explanation that it was due to capacitance of the paper clip or of the wiring. Edison’s telephone magneto explanation is also a perfectly reasonable explanation, although it doesn’t match up as well with the OP’s memory of the device. I guess I’ll ask the OP (if he’s still watching): How long was it between the time the generator was stopped, and the time you removed the paper clip? If it was just a fraction of a second, then the inductance explanation is plausible, and matches better with your not remembering any capacitors. If it was like a half a minute or something, then Edison’s telephone magneto explanation is more plausible. Looking at this picture of a telephone magneto, I can see how you might be under the impression that someone had hand-made the thing from scratch, using the gear assembly and crank taken from an old pencil sharpener. MrRedact (talk) 01:06, 24 February 2008 (UTC)[reply]

Thank you for all your incredibly detailed answers. Also, it was a telephone magneto, the pictures match perfectly (as does my description somewhat). As for the delay between cranking and touching the paperclip, I figure it was about 1 second - and since my memory is fuzzy it could very well have been myself that was cranking the magneto before attempting to remove the paperclip. 206.252.74.48 (talk) 14:03, 25 February 2008 (UTC)[reply]

Medicine

North American Symptomatic Carotid Endarterectomy Trial: Carotid endarterectomy was found to be beneficial for symptomatic patients with carotid stenosis greater than 70%. Does this measurement of 70% stenosis refer to a relative stenosis in diameter or area? 50% stenosis in diameter = 75% stenosis in area. Which is the measurement that tips the scale towards surgery? —Preceding unsigned comment added by 69.74.62.226 (talk) 16:46, 22 February 2008 (UTC)[reply]

It is the area that is measured, and 70% is considered to be the standard threshold for surgical intervention. Though for those who have symptoms between 50-69% surgery may be considered if other treatments fail. Fribbler (talk) 17:17, 22 February 2008 (UTC)[reply]

(ec) Link to NASCET article in Stroke (no subscription required): HTML, PDF

The methods section describes one eligibility criterion as "...a stenosis of 30% to 99% in the ipsilateral carotid artery based on linear diameter reduction" (my emphasis). There's a more detailed description of the eligibility criteria in an earlier volume of Stroke: PDF. This article also includes diagrams of what was measured.

Note that stenoses aren't necessarily uniform, and that the unobstructed lumen won't necessarily be circular in cross-section. In other words, the relationship between linear stenosis and area stenosis isn't perfectly-behaved, mathematically. TenOfAllTrades(talk) 17:36, 22 February 2008 (UTC)[reply]

answers plz (refrigeration vs. air conditioning)

what is the difference between refrigeration and air conditioning? —Preceding unsigned comment added by 202.83.173.61 (talk) 20:57, 22 February 2008 (UTC)[reply]

They're the same concept. The function of a refrigerator is to remove heat from one system, and place it in another. In the case of your typical kitchen refrigerator, heat is removed from the inside, and dumped into the outside. A house with central air conditioning is basically a gigantic refrigerator, which removes heat from the house and dumps it into the air outside. This is why you can't, for example, keep your fridge open and expect it to cool the house down. Someguy1221 (talk) 21:30, 22 February 2008 (UTC)[reply]

If the refrigerator is cooler than the house then the average temperature of the house and the refrigerator is less than the temperature of the house.. if you let them equalize then it would in fact cool down your house. But I guess refrigerators do create waste heat cause they use electricity.. but for a little while at least it would cool your house. :D\=< (talk) 22:57, 22 February 2008 (UTC)[reply]

You're house would have to be incredibly small for that to work...Someguy1221 (talk) 00:42, 23 February 2008 (UTC)[reply]

The area in front of the refrigerator would certainly be cooled significantly- that's why you feel a blast of cold air when you open the freezer.. :D\=< (talk) 00:47, 23 February 2008 (UTC)[reply]

That would only work if the waste heat from the fridge was being expelled outside the house. If you're doing that, you basically have an air conditioning unit. Just to avoid confusing the anonymous person with Froth's silliness. Skittle (talk) 23:24, 24 February 2008 (UTC)[reply]

I think there's a slight diff in the terms in that the goal of refrigeration is only to lower the temperature, while the goal of air conditioning also includes lowering the humidity. That said, refrigeration often causes a reduction in humidity, whether that is the goal or not. StuRat (talk) 01:34, 23 February 2008 (UTC)[reply]

It's in the names themselves. The goal of a refrigerator is to lower the temperature, or refrigerate, the contents. The goal of an air conditioner is to condition the air by controlling the temperature (by heating and/or cooling as needed), humidity (a cooling system will also pull moisture, often a closed system will include a humidifier downstream of the cooling coils) and quality (by filtering dust and debris, and often scrubbing chemicals).

Note that humidity is often automatically controlled by a sensor called a humidistat; linking to that word redirects to the WP article for humidifier, which has a link to humidistat...... -SandyJax (talk) 21:30, 26 February 2008 (UTC)[reply]

Chemical reaction question

KCl + HNO₃ → NR

Why? I figured, since KCl is ionic, and HNO₃ is ionic (right?), HCl (which is covalent) would be formed:

KCl + HNO₃ → KNO₃ + HCl

Well, I was wrong, but why? I guess it's because K is more reactive than H? If so, how do I know when the driving force to form a solid/covalent compound "wins"? Thanks in advance. :) -- Aeluwas (talk) 21:53, 22 February 2008 (UTC)[reply]

HCL is a strong acid, which means it just about completely dissociates in water, just like an ionic compound (so you can think about it behaving like one). HNO₃ by the way is also a strong acid. HNO₃ is also an oxidizer and is some situations will undergo an oxidation reduction reaction to form NO₂ gas and other things, but it doesn't seem to be the case here. What you would get in the solution is the following Sifaka ^talk 22:50, 22 February 2008 (UTC)[reply]

Cl^-(aq) + NO₃^-(aq) + K⁺(aq) + H⁺(aq) (or H₃O⁺(aq) if you prefer)

HCl is a covalent compound, but it is also highly water soluble. In addition, it is a strong acid, which means that when you put it into water, it is almost completely deprotonated (i.e. the H⁺ is removed from the Cl^-). Actually, (pure) HNO₃ is also a covalent, highly water soluble strong acid, just like HCl. When you mix KCl (ionic and highly water soluble) with HNO₃ in water (from the HNO₃ solution you're using), the compounds rapidly dissociate into K⁺, Cl^-, "H⁺" (see hydronium ion for why I put it in quotes), and NO₃^-. What happens next is determined by the solubility product constant for each of the potential products in this double displacement type reaction. We already know that KCl and HNO₃ are highly water soluble, so they will not precipitate. We also know that HCl is also highly water soluble, so it will stay in solution too. That leaves the KNO₃. Potassium nitrate, like KCl, is also a highly water soluble salt, so if you mixed dry KNO₃ with water, it would rapidly dissolve, forming K⁺ and NO₃^- ions. Since we already have K⁺ and NO₃^- ions, nothing further will happen in our reaction. Most potassium and sodium salts are highly water soluble, so no matter what you mix with them, they tend to stay in solution. Contrast that with something like silver salts. AgNO₃ is water soluble, but AgCl₂ is not. If you mix AgNO₃ with a hydrochloric acid solution, you'll see the formation of AgCl₂ as a solid, and you'll have the formation of HNO₃, which will stay dissolved (as H⁺ and NO₃^-). -- 128.104.112.47 (talk) 22:59, 22 February 2008 (UTC)[reply]

Nice answer by the way. Sifaka ^talk 23:01, 22 February 2008 (UTC)[reply]

Great answers, both of you! Thanks a lot. -- Aeluwas (talk) 09:58, 23 February 2008 (UTC)[reply]

is it two seconds or four seconds to moon and back?

If you say something, will it take 2 seconds or 4 seconds to hear the other person's "yes" "no" etc response? —Preceding unsigned comment added by 79.122.91.82 (talk) 22:07, 22 February 2008 (UTC)[reply]

You're talking about sound getting to the moon? It won't get there- sound travels through air (or sometimes other matter), but not empty space. Friday (talk) 22:08, 22 February 2008 (UTC)[reply]

I assume he means via radio or something else that travels at the speed of light. In which case, it should take (less than) 1.35 seconds in either direction, or 2.7 seconds both ways. -- Aeluwas (talk) 22:10, 22 February 2008 (UTC)[reply]

Anyway, don't forget that the distance from the Earth to moon is highly variable especially between perigee and apogee. Hope this helps. Thanks. ~A H 1^(TCU) 01:02, 26 February 2008 (UTC)[reply]

Significant time-delay for radio propagation may occur as the signal passes through the ionosphere. In this region, the speed of light (or radio waves) is variable based on direction, frequency, temperature, butterfly-wing-flaps, etc. (Note that the speed of light is constant in a vacuum, but the region of charged particles near earth is decidedly not a vacuum!) Nimur (talk) 22:20, 27 February 2008 (UTC)[reply]

Unrelated to the original question

Anyway electromagnetic radition could never escape the gravitational field of the earth.. you should be thankful for that, or we'd all be scorched to a crisp by the untempered fury of the Sun.. not to mention the roar of noise from nuclear fusion in the core, which would be overwhelming without any atmosphere in space to slow it down. :D\=< (talk) 23:32, 22 February 2008 (UTC)[reply]

What on earth are you talking about? Your post, as far as I can understand it, is completely incorrect. Friday (talk) 23:47, 22 February 2008 (UTC)[reply]

It is completely incorrect. Electromagnetic radiation can't leave the earth? Infared, microwaves, radio waves, and light can all leave the earth quite easily. Wisdom89 _{(_T / ^C)} 23:50, 22 February 2008 (UTC)[reply]

Seriously Froth, what's up? Been wondering for a while now if your account's been compromised. 79.74.0.57 (talk) 23:58, 22 February 2008 (UTC)[reply]

The wrong crowd :/ Who are you by the way? :D\=< (talk) 00:46, 23 February 2008 (UTC)[reply]

I'm confused. You used to be a computer science student named Brian and now you're "54-year-old grandmother writing a novel in her spare time"? It looks to be like we need an admin to shut down this account until the real Froth can provide his user committed identity. (EhJJ)^TALK 04:48, 23 February 2008 (UTC)[reply]

I've sent a ~~request of administrative action.~~ ~~Please comment there, whether you agree or disagree.~~ (EhJJ)^TALK 14:12, 23 February 2008 (UTC)[reply]

lol metadiscussion. Yeah it's me, don't mind me. I blanked my userpage to change from the well-behaved Froth persona to the still-helpful EFG persona that's not afraid to screw around for lulz. I guess it's a stage of my life spiraling downward. *shrug* Also why were you going to ban me.. if my account was compromised the real me would come forward with the hash text to reclaim my account. All aboard the light-current's fate train, toot toot! :D\=< (talk) 15:42, 23 February 2008 (UTC)[reply]

Someone knocking on my coffin? Be careful: you might bring me back to life 8-)--HideousCrumpet (talk) 22:22, 23 February 2008 (UTC)[reply]

:O :O :O :O :O :D\=< (talk) 05:16, 24 February 2008 (UTC)[reply]

Also the grandmother thing was because I had asked a perfectly legitimate medical information question regarding the novel I'm writing. I could very well have been some casual user very offended by the accusation that I'm seeking free medical help. :D\=< (talk) 15:46, 23 February 2008 (UTC)[reply]

Yeah, this should have been moved to the talk page a long time ago. Anyway, I've dropped my original complaint. (EhJJ)^TALK 16:36, 23 February 2008 (UTC)[reply]

Purple veins

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

A thinly-disguised request for a diagnosis is still a request for a diagnosis. Have your novel's character (ha, ha) see a doctor. MrRedact (talk) 01:36, 23 February 2008 (UTC)[reply]

Well I never! I'm a 54-year-old grandmother writing a novel in her spare time. At the next bridge tournament, I'll be sure to tell all the ladies never to ask for help from Wikipedia. Hmph! :D\=< (talk) 04:04, 23 February 2008 (UTC)[reply]

I also have a large purple vein on the underside of my cock that seems to be getting bigger. Should I see the nurse to reduce the swelling, or should i take matters into my own hands?

What makes protiens

I read the page on protiens. It explained what protiens were made of but not what made them. Also, do single cell organisms have DNA & RNA? cris —Preceding unsigned comment added by 75.145.213.217 (talk) 23:16, 22 February 2008 (UTC)[reply]

Yes all single cell organisms have both DNA and RNA. Viruses, which are not considered living organisms may have only one of the two. Ribosomes make proteins. The info you were looking for in the protein article is found here Sifaka ^talk 23:24, 22 February 2008 (UTC)[reply]

(ec) Yes. What you are describing is the central dogma of molecular biology. That is, all cells (single-cell and multicellular organisms) have DNA. They transcribe this DNA into mRNA and then that mRNA is translated into proteins. (EhJJ)^TALK 23:26, 22 February 2008 (UTC)[reply]

Thank you! —Preceding unsigned comment added by 75.145.213.217 (talk) 00:01, 23 February 2008 (UTC)[reply]

Is the unknown information transfer from protien to RNA and protien to DNA how science speculates that DNA and RNA first formed? (Central dogma of molecular biology) —Preceding unsigned comment added by 75.145.213.217 (talk) 01:01, 23 February 2008 (UTC)[reply]

RNA can have enzymatic functions. There is a suggestion RNA may have originally performed the function of proteins and DNA [10]. This would have transitioned to RNA and proteins then probably RNA, proteins and DNA Nil Einne (talk) 01:12, 23 February 2008 (UTC)[reply]

This is called the RNA world hypothesis. (Internal Wikipedia link for those interested, the link posted by Nil Einne is good too.) -- 128.104.112.47 (talk) 21:22, 23 February 2008 (UTC)[reply]

February 23

moon in past

bsm. Is it correct that the moon at least one time taked part (tow parts) and then joined? if that is correct, when and how many?(10-12)

Ideas for prosthetic communication devices for 'locked in' syndrome

I recently saw the 'true story' movie "Diving Bell and the Butterfly" about Frenchman Jo-Dominique Bauby, who suffers a devastating stroke which leaves him with the use only of one eye. This is ‘locked-in’ syndrome, as he cannot move, eat or talk, but can feel and think as before. The film concerns itself largely with his and his speech therapists’ efforts to provide him with the means to communicate once again with the outside world. This involves the speech therapist reciting the alphabet (arranged in order of most-frequently used letters), with Jean-Do blinking when the desired letter is reached, and then repeating the procedure ad infinitum. At an excruciatingly snail-like pace, Jean-Do spells out words, then sentences. As last he writes the eponymous book of his ordeal, and then dies-of pneumonia. Surprisingly, the film is often humorous, although the end-credits blooper reel was nowhere to be seen.

Now perhaps I’ve got that new-fangled Asparagus Syndrome, or my nasty male left brain is working overtime, but while the rest of the theatre were blubbing, I was thinking ‘Is reading the alphabet REALLY the best and only way they could get poor old Jo to talk? And this is in France, a world leader in medicine and medical technology. True, the events of the film are from 1995, but this laborious method of communication could just as readily have been utilized in 1700 rather than 1995!

Stephen Hawking is similarly afflicted, now having even less bodily control than Jean-Do did, and he can just about sing ‘I did it my way!’ I was thinking of fairly low-tech prosthetic to the problem, and I came up with this.

The film shows him as having perfect control over his right eyeball, yet there is no attempt to utilize this fine motor control for communication. How about fitting a contact lens for this eye in which might be embedded a small reflective disk? Now shine a soft light on this eye, and it should reflect a beam. Jean-Do could aim that beam at a display board on which are arranged letters and common words. When that beam had clearly settled on a letter, the system would beep, and that would be Jean-Do’s cue to blink, thus entering the letter to a string being built up. For more feedback, speech production software could read aloud the words as Jean-Do is creating them and provide anticipatory options, to be selected by choosing ‘Yes’ from the board.

I could hardly credit that the rest of this poor man’s life was spent listening to nurses sprouting the alphabet again and again and again. Sure, it was an excuse to perv down their cleavage, and they were hot, but this is ridiculous.

Anyone can throw a ray of light on this? After all, Jean-Do could be any of us—he is, ironically, our everyman, John Doe. Myles325a (talk) 00:23, 23 February 2008 (UTC)[reply]

There's been a lot of work towards creating a brain-computer interface to help people in this situation. See the work by Michael Black from Brown University... especially his work on neuromotor prothesis development. Sancho 01:25, 23 February 2008 (UTC)[reply]

Sorry, I can't remember any details, but at a computer/medical show about 15 years ago, I saw just such a contraption. The person would be wearing a sort of cap with a device that shined a IR beam at the eye and "looked" at the reflection. This information was sent to a computer, and the monitor has the representation of a keyboard on it, with a blinking cross showing where the person was looking. So s/he would just move the cross to the letter and then blink. The blink would "enter" the letter. There were also some editing functions available. Bunthorne (talk) 19:14, 24 February 2008 (UTC)[reply]

Thanks Ariel, that’s pretty much the sort of thing I was thinking of. I’ve just now rewritten the Dasher article for clarity and to put some stress on the possibility of it being used for prosthetic purposes. In my speculation above, a contact lens was used, but of course, there would be probably no need to do even this. Myles325a (talk) 05:55, 27 February 2008 (UTC)[reply]

How Composite Quantum System Relates to Tensor Product?

Consider two noninteracting systems $A$ and $B$ , with respective Hilbert spaces $H_{A}$ and $H_{B}$ . The Hilbert space of the composite system is the tensor product

H_{A}\otimes H_{B}

8

My question is why the composite Hilbert space of the two noninteracting systems is their tensor product as (8)?

It always be true the tensor product is accounted for the concept of composite quantum systems, quantum entanglement especially. As well, it is a big deal with respect to quantum computation. The massive Hilbert space of the composite system dramatically boosts the power of quantum computers. According to postulate of quantum mechanics, the Hilbert space of a composite system is the Hilbert space tensor product of the state spaces associated with the subsystems. But it's rare to see any article which can point out where such a postulate comes from. Is the postulate due to the overwhelming, experimental evidence? Is it a derivational consequence from fundamental quantum theory?

It's difficult to convince me of the ability and the power of quantum computation if no one can tell how the composite quantum system relates to the tensor product. Hopefully, the postulate came from the derivational consequence of quantum theory rather than just from the experimental evidence. After reviewed the original EPR paper, I came up with an idea. So I tried to explain it myself. Although the explanation is very likely to be wrong and even seems naive and optimistic, I would like to put it here to see if anyone could give some advice or correction to my faults. For simplicity, the following assumes all relevant state spaces are finite dimensional.

For a composite system of two particles $A$ and $B$ , the wave function is

\Psi (x_{1},x_{2})

1

where $x_{1}$ and $x_{2}$ are respective positions of $A$ and $B$ . Similar to the idea of Separation of variables for solving PDE discovered by Leibniz, if the wave function can be separated into multiplication of two functions such that

\Psi (x_{1},x_{2})=U(x_{1})V(x_{2})

2

As a result, the functions $U(x_{1})$ and $V(x_{2})$ can be viewed as wave functions for $A$ and $B$ , respectively. Furthermore, $U(x_{1})$ and $V(x_{2})$ are in Hilbert spaces $H_{A}$ and $H_{B}$ , respectively. Therefore, the two functions can be expanded by their related basis such that

U(x_{1})=\sum _{i}a_{i}|i\rangle _{A}

3

V(x_{2})=\sum _{j}b_{j}|j\rangle _{B}

4

where $\{|i\rangle _{A}\}$ and $\{|j\rangle _{B}\}$ are respective sets of basis for $H_{A}$ and $H_{B}$ . Substitute (3) and (4) into (2), we have

\Psi (x_{1},x_{2})=\left(\sum _{i}a_{i}|i\rangle _{A}\right)\left(\sum _{j}b_{j}|j\rangle _{B}\right)

$=\left(a_{1}|1\rangle _{A}+a_{2}|2\rangle _{A}+...+a_{m}|m\rangle _{A}\right)\left(b_{1}|1\rangle _{B}+b_{2}|2\rangle _{B}+...+b_{n}|n\rangle _{B}\right)$

=\sum _{i,j}a_{i}b_{j}|i\rangle _{A}|j\rangle _{B}

5

Since $|i\rangle _{A}$ and $|j\rangle _{B}$ are in different Hilber spaces, their multiplication is equivalent to their tensor product. Thus

|i\rangle _{A}|j\rangle _{B}=|i\rangle _{A}\otimes |j\rangle _{B}

6

Substitute (6) into (5), we have

\Psi (x_{1},x_{2})=\sum _{i,j}a_{i}b_{j}\left(|i\rangle _{A}\otimes |j\rangle _{B}\right)=\sum _{i,j}a_{i}b_{j}|ij\rangle _{AB}

7

That (7) is a state or vector in Hilber space $H_{A}\otimes H_{B}$ . And (7) can be generalized to systems that involve more than two particles or subsystems. However, it is problematic such as

The method of the separation of variables can not guarantees to be the solution for every class of PDE. Likewise, not all wave function of form (1) can be separated into multiplication of two functions of form (2).
Even if the wave function (1) could be separated to the form of (2) "mathematically", but does it make physical sense to say that the functions $U(x_{1})$ and $V(x_{2})$ are two "wave functions" which are the component systems of $\Psi (x_{1},x_{2})$ ?

Well, I am neither a mathematician nor a physicist. I don't mean to offend or mislead someone with my words. I am just hoping to get more clue about answering the question "How Composite Quantum System Relates to Tensor Product?" with this discussion. Thanks! - Justin545 (talk) 00:50, 23 February 2008 (UTC)[reply]

Truth is a very difficult concept (with apologies to Alan Clarke MP (deceased))

All of your math looks right. As you say, some states of the composite system can be written in this way and some can't; those that can are called separable. It's correct to refer to U and V as wave functions, and in fact all wave functions are like that. You can't describe the whole universe with a wave function, only separable parts of it.

There's nothing quantum mechanical about the idea of phase space or separability or combining systems by taking the tensor product. For a classical analogy, take a system of three classical bits. This system has 2³ = 8 states, which can be written

|000\rangle

,

|001\rangle

, and so on. An example of a computational step on these bits might be "flip the third bit if at least one of the first two is set", which can be written with the transition matrix

\scriptstyle \left({\begin{array}{cccccccc}1&&&&&&&\\&1&&&&&&\\&&&1&&&&\\&&1&&&&&\\&&&&&1&&\\&&&&1&&&\\&&&&&&&1\\&&&&&&1&\end{array}}\right)

(all other entries zero). You can think of this matrix as acting (by left-multiplication) on a state vector, which is an 8-component column vector that has a 1 at the index corresponding to the state of the system and zeroes everywhere else. (So

|000\rangle

is (1,0,0,0,0,0,0,0)^t,

|001\rangle

is (0,1,0,0,0,0,0,0)^t, and so on.) Or, more generally, you can think of it as acting on a probability distribution over possible states of the computer, for example

{\frac {1}{3}}|001\rangle +{\frac {2}{3}}|011\rangle =(0,{\frac {1}{3}},0,{\frac {2}{3}},0,0,0,0)^{t}

. The probabilities all have to be between 0 and 1 and they must sum to 1. If you only allow reversible computations, then the only matrices that preserve that property are the permutation matrices.

If you have two of these computers, you can describe them as a single system using the 64-dimensional tensor product of the individual 8-dimensional phase spaces, for which the natural basis is

|000\rangle |000\rangle ,|000\rangle |001\rangle ,\ldots ,|000\rangle |111\rangle ,|001\rangle |000\rangle ,\ldots

. As long as the two subsystems don't interact, the composite state can be written as a tensor product of the states of the subsystems (as you did above), and the transitions can be written as the matrix tensor product of the transitions of the subsystems. If the subsystems do interact (e.g. a bit in one is flipped or not flipped depending on a bit in the other), then the subsystems may become correlated, in which case they can't be written this way any more.

To get quantum computing from this, all you do is replace the classical probabilities which sum to 1 with complex numbers whose squared absolute values sum to 1. Because the square norm is much more symmetric (the space of valid vectors is a sphere instead of a simplex), there are a lot more reversible computations you can do; in fact, any unitary matrix is a valid computation. Permutation matrices are unitary matrices, so classical computations are a subset of quantum computations. The quantum states that would be called "correlated" classically are called "entangled" instead. I do think a new name is justified because there is something new in the quantum case, namely violation of Bell's inequality, but the mathematics is the same.

It's unfortunately true that a lot of introductions to quantum computing don't explain the connection to classical computing and often attribute the extra power of quantum computers to the exponential size of the phase space ~~or to entanglement~~. ~~Neither explanation makes~~This explanation doesn't make much sense given that ~~both of these properties are~~this property is inherited from the classical case. (Edit: I think it was a mistake to mention entanglement here since there are different notions of entanglement, and it's reasonable to relate quantum computing to entanglement in some senses.) The real nature of the extra power of quantum computers isn't well understood. There seems to be a class of problems in between P and NP which is efficiently solvable on quantum but not classical computers. It includes interesting number-theoretic problems like factoring and discrete logarithm, and it may be related to public-key cryptography somehow. To my knowledge the only interesting quantum algorithm outside that class is Grover's algorithm, which is often described as "database search" but is actually a SAT solver. It's faster (in the worst case) than the best known classical algorithm, but still very slow. No one has found an efficient quantum algorithm for any NP-complete problem, and it seems likely that there aren't any. In other words, a quantum computer's power seems to be very limited compared to the naive idea of a parallel-universe computer that does exponentially many calculations in parallel, since such a computer could solve NP-complete problems efficiently (basically by the definition of NP).

If you don't like the Hilbert space and the tensor products and the exponential size, you can look at the path integral formulation of quantum mechanics. It coexists with the Hilbert space approach because a lot of problems are much easier to solve in one than the other. You might also be interested in this paper. -- BenRG (talk) 19:34, 23 February 2008 (UTC)[reply]

Your answer is pretty clear and understandable, especially when you are explaining the transition matrix of the 3-bit computer. My understanding of your answer is that interacted=entangled=correlated and non-interacted=separable. But some new problems appear after reading:

1. Consider the two paricles

A

and

B

in my qestion above. When they are entangled, or non-separable, the wave function

\psi (x_{1},x_{2})

can NOT be written as separated wave functions multiplication

U(x_{1})V(x_{2})

. Therefore, we may NOT write

\Psi (x_{1},x_{2})=\sum _{i,j}a_{i}b_{j}\left(|i\rangle _{A}\otimes |j\rangle _{B}\right)

Does that mean the entangled state space of the composite system is NOT in

H_{A}\otimes H_{B}

? However, we can still see several examples of entanglement that the state of the composite system is written in term of the basis of

H_{A}\otimes H_{B}

such as the following entangled state:

|\Psi \rangle ={1 \over {\sqrt {2}}}{\bigg (}|0\rangle _{A}\otimes |1\rangle _{B}-|1\rangle _{A}\otimes |0\rangle _{B}{\bigg )}

It seems contradictory...

2. How to determine two particles whether they are conposite or non-composite? Can we say the two particles is two non-composite systems when they are distanced far away, and they are one composite system when they are very closed to each other like the electron and the proton in a hydrogen atom?

Well, I am not quite understand the quantum computing. I think the quantum computer can only solve decision problems such as SAT, but not problems which is sort of like programming that needs many step of calculations. There seems to be many problem useful but belong to NP-complete which is not likely to be solved by quantum computer. It sounds somewhat disappointing. We don't know if the quantum computer is an useful and universal machine even if we can really make a 500-bit (or more then 500-bit) of quntum computer. - Justin545 (talk) 03:51, 24 February 2008 (UTC)[reply]

Apologies for neglecting this thread. On your first point, the state space IS

H_{A}\otimes H_{B}

, but you can't write arbitrary elements of that space as a sum of products of elements of the subspaces weighted by a_ib_j. You can write arbitrary elements with arbitrary weights c_ij. There are no

a_{0},a_{1},b_{0},b_{1}\in \mathbb {C}

such that

a_{0}b_{1}=-a_{1}b_{0}=1/{\sqrt {2}}

and

a_{0}b_{0}=a_{1}b_{1}=0\,\!

, but there are

c_{00},c_{01},c_{10},c_{11}\in \mathbb {C}

such that

c_{01}=-c_{10}=1/{\sqrt {2}}

and

c_{00}=c_{11}=0\,\!

. On the second point, particles that are causally interacting like the electron and proton need to be treated together, and particles that aren't causally interacting can usually be treated separately even if they're nonclassically entangled. The only case where the entanglement of noninteracting particles matters is if you do measurements on both particles and later compare the results; then you can get nonclassical correlations. If you're only doing measurements on one particle then you can always describe it without reference to the other. If the two particles are unentangled then your particle can be represented by a state vector; otherwise it has to be represented by a density matrix. Measuring a property of your particle destroys its entanglement with the other particle (in that property), so once you've measured all the properties that the density matrix says you're classically uncertain about, you can again represent your particle by a state vector. Incidentally, I shouldn't have said that entanglement is just the quantum name for correlation, since it's often used to mean just the nonclassical part of the correlation (the part that violates Bell's inequality).

Quantum computers are universal; they can solve the same problems as classical computers with the same efficiency as classical computers, in terms of big-O notation. But there's not much point using a quantum computer to run a classical algorithm, especially because the constant factor will probably be enormously higher. There are some specific problems for which specifically quantum algorithms are known, but, as you say, they mostly don't seem very useful. There's a big exception that I forgot to mention, which is simulation of quantum systems. I don't know anything about this, but I think that quantum computers could potentially revolutionize fields like lattice QCD. Also, a large quantum computer is a great test of the principles of quantum mechanics; successful factorization of the RSA challenge numbers would be a dramatic confirmation of quantum mechanics and would definitively falsify a large class of hidden variable theories, and for that reason alone I think it's an experiment worth doing. -- BenRG (talk) 16:20, 27 February 2008 (UTC)[reply]

Indeed, you have done a pretty good job to prove why the entangled state below

|\Psi \rangle ={1 \over {\sqrt {2}}}{\bigg (}|0\rangle _{A}\otimes |1\rangle _{B}-|1\rangle _{A}\otimes |0\rangle _{B}{\bigg )}

9

is not separable i.e. the state can not be writter in the form of (7). Since you have proven there are no numbers

a_{0},a_{1},b_{0},b_{1}\in \mathbb {C}

which can satisfy the conditions you listed above. It it understandable and clear. I apologize for obscuring my question last time. I attempt to clarify my question again.

We have proven the state of a composite system is in

H_{A}\otimes H_{B}

if the state is separable. That's because when the state of a composite system is separable, the corresponding wave function can be written in the form of (2) which also implies (7) is true and therefore we can say the state of the composite system is in

H_{A}\otimes H_{B}

. Moreover, we have also proven a separable state has

m*n

basis, which is just a basic property of tensor product, when

H_{A}

has

m

basis and

H_{B}

has

n

basis.

However, it is not enough to say "all" of states of composite systems are in

H_{A}\otimes H_{B}

. We have only proven that all of "separable" states are in

H_{A}\otimes H_{B}

(like what I did from step (1) to (7)), but we "have not" proven all of "non-separable" (entangled) states are in

H_{A}\otimes H_{B}

. Since any state of a composite is either separable or non-separable (entangled), we can not say "all" of states are in

H_{A}\otimes H_{B}

until we can prove "both" separable and non-separable (entangled) states are in

H_{A}\otimes H_{B}

.

Then my question last time was "How to prove all of non-separable (entangled) states of any composite system are also in

H_{A}\otimes H_{B}

?". For example, if we take a look at the non-separable (entangled) state (9), we can find the state is in

H_{A}\otimes H_{B}

since its basis

|0\rangle _{A}\otimes |1\rangle _{B}

and

|1\rangle _{A}\otimes |0\rangle _{B}

are in

H_{A}\otimes H_{B}

. But I have no idea where the two basis

|0\rangle _{A}\otimes |1\rangle _{B}

and

|1\rangle _{A}\otimes |0\rangle _{B}

come from. The state (9) is denoted in bra-ket notation, but I have no idea how does its corresponding wave function look like. Can we use the similar way (like what I did from step (1) to (7)) to prove all of non-separable (entangled) states of any composite system are also in

H_{A}\otimes H_{B}

? If we can prove it, we will be able to say "all" of states of composite systems are in

H_{A}\otimes H_{B}

and we can also explain how a wave function for a separable or non-separable state relates to its bra-ket notation. - Justin545 (talk) 01:42, 3 March 2008 (UTC)[reply]

Turing has proven that Turing machine is universal. If we can simulate a Turing machine on a quantum computer, we may prove quantum computer has the ability as strong as Turing machine and therefore it is universal. However, as you said, there's not much point using a quantum computer to run a classical algorithm, it would be required to combine quantum computer with classical computer to achieve similar function of Turing machine.

I agree with you it's an experiment worth doing. But I am afraid that quantum computers are not scalable (well, I'm not sure). Although D-Wave has announced a working prototype of 16-qubit (or even more qubits later) quantum computer, there seems to be some coupling problem with the prototype. It sounds like D-Wave simply put four quantum computers, each of which is 4-qubit, together. I can not see any significant advances when we are talking about if quantum computers are scalable. On the other hand, keeping the system entangled is also difficult, especially when more quanta are involved. Which would limit the time to do quantum operation and therefore limit the complexity of the problems it can solve. Some experts predicted useful quantum computers would appear after one or two decades. Is it just a matter of time? Well, I am not so sure. By contrast, DNA computers are more stable than quantum computers. But DNA computing does not provide any new capabilities from the standpoint of computational complexity theory. It seems only quantum computers have such potential. Other than quantum computers and DNA computers, aren't there any other natural analogies to quantum computers but also stable enough? That question drives me to study why quantum computers are so powerful from mathematical point of view. - Justin545 (talk) 08:56, 3 March 2008 (UTC)[reply]

worst animals

What are the most poorly evolved species? My example would be that the panda is pretty crap; it only eats one thing, has vast territories but lives alone and is barely fertile because of its nutrient-lacking diet. Are any other species (or am I wrong about the panda?) that are poorly developed for survival? 81.96.160.6 (talk) 01:34, 23 February 2008 (UTC)[reply]

If an organism was so poorly adapted/designed for survival, it would be quickly weeded out as there would be no way to pass on its advantageous genotypes to progeny and future generations. I think you might be oversimplifying the Panda's survival and adaptability. Wisdom89 _{(_T / ^C)} 01:47, 23 February 2008 (UTC)[reply]

I thought the deal with pandas is that they don't usually 'do well' when raised/looked after by humans? --Kurt Shaped Box (talk) 02:57, 23 February 2008 (UTC)[reply]

Yes, but what does that tell you? One should infer that artificial care disturbs the ability of the Panda to thrive, not that the animals are ill suited for survival. Biological evolution is clear in that it is not a linear hierarchal ladder of lower/inferior life forms running all the way up to humans. Evolution is not progression. Wisdom89 _{(_T / ^C)} 05:07, 23 February 2008 (UTC)[reply]

That was kinda the point I was trying to (badly, late at night) make. That it doesn't do well when looked after by humans is not an indication that it's a poorly evolved species. --Kurt Shaped Box (talk) 12:46, 23 February 2008 (UTC)[reply]

Ah ok then, yes your point is valid then : ) Wisdom89 _{(_T / ^C)} 16:38, 23 February 2008 (UTC)[reply]

The cranefly has a *very* crappy 'design' - the worst I can think of. Large, slow, defenceless, fragile, docile, a weak flyer *and* (apparently) good eating. They do have sheer weight of numbers behind them, however. So the species survives. --Kurt Shaped Box (talk) 02:53, 23 February 2008 (UTC)[reply]

The dodo was a pretty good case-study of a "poorly evolved" species. Due to its isolation from predators, it never evolved a fight-or-flight response and was easy pickings for the human settlers. -- MacAddct  1984 ^{(talk  contribs)} 05:21, 23 February 2008 (UTC)[reply]

None of those are good answers, I feel. The Dodo was not poorly evolved to its environment, it did well until humans and cats were added. The Panda was not poorly evolved to its environment, it did well until the bamboo forests started to get decimated. South American marsupials were doing nicely thankyou - until North America joined up and added superior predators. They all suffered because their environment changed, so of course they are poorly adapted to the environment they now find themselves in, that is not the same as poorly evolved. You would probably not do too well if you were to be suddenly dumped out of your comfort zone into, say, the bottom of the Marianas trench or Low Earth Orbit.

Which is why I put "poorly evolved" in quotes. Like someone said further up, if a species was truly poorly evolved, it would just die off quickly in its own environment. Evolution/natural selection wouldn't work if poorly evolved species managed to live (the exact opposite of what natural selection means). With the dodo example, one could just as easily say humans are poorly evolved because we wouldn't survive nuclear annihilation. -- MacAddct  1984 ^{(talk  contribs)} 15:46, 23 February 2008 (UTC)[reply]

A better choice for poorly evolved is certain species of tree kangaroo. These have only recently evolved from regular kangaroos and some species are exceptionally bad climbers, presumably because their evolution is still a work in progress. SpinningSpark 15:23, 23 February 2008 (UTC)[reply]

My vote goes to the Bread-and-Butterfly. —Preceding unsigned comment added by Milkbreath (talk • contribs) 17:13, 23 February 2008 (UTC)[reply]

There is no such thing as "poorly evolved." There are, however, times in which an organism is not "fit" for a given environment. As environments change, that possibility becomes very great. Most endangered species today are quite fit for the environment in which they evolved, but have been unable to cope with new invasive species (human beings) who change that environment. If you are asking "what species today are the least adaptive to the present world," well, look at the endangered species list. --98.217.18.109 (talk) 17:17, 23 February 2008 (UTC)[reply]

I always tell my kids that pandas are poorly evolved too, so you're not alone. Probably when an organism exploits an ecological niche, the first 1000 generations are ecologically fragile. Then some mutation occurs which would have been harmless or harmful in the original niche, but is beneficial in the new niche. Delmlsfan (talk) 17:45, 23 February 2008 (UTC)[reply]

How frequently do you tell this to your kids? :) ----Seans Potato Business 20:44, 23 February 2008 (UTC)[reply]

Thanks guys, your answers have been great. I would have thought more animals would have some inherent flaws, though. thanks! 81.96.160.6 (talk) 22:14, 23 February 2008 (UTC)[reply]

You might look at inefficiencies in design as a measure of "flaws" in which case humans would qualify. I recall Flock of Dodos had a bit about rabbits having to process food through their digestive system twice to get the nutrients. — Æµ§œš¹ _{[aɪm ˈfɻɛ̃ⁿdˡi]} 23:36, 23 February 2008 (UTC)[reply]

This whole "poorly evolved" concept seems to be part of the mistaken "evolution as progress" metaphor that the late Stephen Jay Gould tried hard to combat in his books. As has been pointed out, there is no absolute poroly evolved/well evolved scale - organisms evolve to fit a particular environment, so goodness of fit is relative. If the environment changes rapidly (on a geologic timescale) then a species may find themselves in a environment to which they are no longer adapted. The environment, of course, includes other orgnaisms. So you could argue that the dodo was very well fitted to an environment with no ground-based predators - why waste energy flying if you don't need to ? The penguin followed a similar evolutionary path, but had the additional requirement of having to find its food in the sea. Humans are very poorly adapted to the environment around a hydrothermal vent - in that environment, we are "poorly eveolved", but other organisms, commonly thought of as occupying a much lower rung on the "evolutionary ladder", are very well adapted. Gandalf61 (talk) 11:48, 24 February 2008 (UTC)[reply]

Wouldn't it take a lot less energy to keep a tiny little bird airborne than for a 40 pound bird to run around? :D\=< (talk) 12:48, 24 February 2008 (UTC)[reply]

Humans ,as we're doing a darn good job of destroying our own habitat and each other.^{(Hypnosadist)} 17:01, 24 February 2008 (UTC)[reply]

I understand that evolution isn't progress. I just thought that surely some unfavourable traits survive in the enormous variety of species that exist. I would have thought there'd be a few leftovers that maybe aren't that great. Poorly evolved was a bad way of putting it, I guess. 81.96.160.6 (talk) 18:59, 24 February 2008 (UTC)[reply]

There are definitely a lot of traits that are generally considered 'unfavourable' in most environments. The design of the eye is an ofcited exampled [11], usually in response to ID proponents since it's a flawed design (although this doesn't rule out an imperfect designer). Even the peacock tail could be said to be an unfavourable trait of sorts. It's only purpose appear to be to attract a mate (although why is uncertain see [12]) and the peacock pays a heavy price for it. There are surely much better ways to carry out it's function. However these traits are not enough of a problem that they prevent the organisms which have them from surviving so the species as a whole can't be said to be 'poorly evolved'. They have simply evolve how they have evolve and have traits are what they are. From a design point of view, there is surely a better way to do things, but it doesn't matter since the evolve traits work however they work well enough Nil Einne (talk) 09:57, 25 February 2008 (UTC)[reply]

Built-in Radio

Speculatively speaking, if you embedded a radio transceiver in somebody's body, it would be surrounded by (mildly) conductive material. Would it need an additional antenna? If you were to attach a long, slender piece of metal, like an antenna, to an appropriately shaped bone (like a femur, or maybe a clavicle), would it work better? Or would it be inhibited by the skin and such around it? Disclaimer: This is purely hypothetical; I am not planning on building a cyborg. Faithfully, Deltopia (talk) 02:40, 23 February 2008 (UTC)[reply]

Even a hypothetical answer would need some more details on the application to give an accurate answer. First of all, the size of antenna is primarily determined by the radio wavelength the device is using. There are many different types of antenna, but most often the elements of an antenna are close to one quarter of the wavelength. For a device operating in the UHF or SHF bands this would be of the order of centimetres or millimetres and could probably be incorporated in the device itself. You start to get more of a problem as you come down the spectrum to lower VHF and MW but you still might be able to avoid a messy insertion into a leg bone by using fine guage copper wire wound on a ferrite core.

You say transceiver, so presumably you need to get information out as well as telecontrol. In that case transmission (Tx) power is also an issue. Certainly, you are right that the conductivity of the body will absorb some of the radio power through joule heating, but if you are only trying to get as far as the surface of the skin there should not be any insuperable problems. To transmit any distance, the Tx power will have to be increased, and you will reach a point where the radiation is damaging to the human body. The article Mobile phone radiation and health has a good discussion of the issues here. It is also possible to keep the power down by use of a directional antenna (Yagi for instance) but then you have the difficulty of keeping the subject facing the right direction.

Disclaimer: ask a professional surgeon to help before trying this on any member of your family. SpinningSpark 14:51, 23 February 2008 (UTC)[reply]

See Capsule endoscopy. A cell phone works when you wrap yourself around it. A wire in the body could probably be made to work, but a rubber-ducky-style antenna works just fine for most things and could be inside the device. --Milkbreath (talk) 15:33, 23 February 2008 (UTC)[reply]

Also see Radio-frequency identification#Human implants. MrRedact (talk) 16:28, 23 February 2008 (UTC)[reply]

My recommendation would probably be an "inverted F" antenna rather than rubber ducky as it can be printed on the device pcb and therefore entirely contained within the device (no medical sealing problems). But as I said, the feasibility depends a lot on the application. Deltopia, please tell us what you are thinking of doing - we are forbidden to give medical and legal advice but dangerous and immoral advice is not specifically excluded anywhere (I think). SpinningSpark 16:45, 23 February 2008 (UTC)[reply]

Sorry, I probably should have been more clear from the start. I was going to write a short story about a person who was in constant radio contact with someone else, set in modern or near-modern times. I am beginning to think that using Tom Cruise's eyeglasses from the first Mission: Impossible will be more pragmatic than implants (and a lot easier to remove at the end of their usefulness), but I wanted to explore the possibility. I always hate reading a book and thinking, That would never work! The machine gun would kick too strongly, or the barrel would melt, or you'd run out of oxygen! So I don't want people to think that while reading my work. Thanks for the help! Faithfully, Deltopia (talk) 23:21, 23 February 2008 (UTC)[reply]

No reason it should not work in principle. Presumably your issue is to hide the comms from prying eyes. If you use cellular technology, you will get the same coverage as you would with mobile phones (so no working in tunnels, in the middle of the moors etc). Your hero might have a problem with security on a public network though (don't know your story so don't know if this is an issue). In the UK the emergency services have a cellular network called Tetra and this WILL work in some tunnels at least. Don't know that there is an equivelant in the States (I think thats where you are), my understanding is that emergency service comms are patchy in the US, not covering the whole country and not even being the same system everwhere. It depends how far your hero is going to travel what is feasible. If your hero is working for a government security service you can just invent a system - who's to say they don't actually have it. You would also need to invent a way for him/her to control the device, if it is not on all the time. Don't forget also that he will need to hear the audio (I didn't know we were talking about voice comms before - your comment about cyborgs threw me) so you will need a cochlea implant or similar. To avoid running wires through the body from the ear to wherever you decide to put the transceiver, use something like Bluetooth technology to link them. SpinningSpark 01:39, 24 February 2008 (UTC)[reply]

To address your concern about conductivity: Yes, it would be a problem, if you want to work at the high frequencies (short wavelengths) where the antenna issue is easy. The UHF and SHF bands mentioned above correspond to frequencies around 1 GHz and 10 GHz respectively. At 10 GHz, the absorption length of even pure water is about 1 mm, so very little of your signal would make it through several cm of tissue. At 1 GHz, the absorption length of pure water is about 10 cm (much better!), but that of sea water is still less than 1 cm (Ref: Jackson, Classical Electrodynamics.), and that of tissue will be intermediate between these two. A quarter-wave antenna at 1 GHz is 75 mm long, which is a bit inconvenient but not impossible if positioned along a bone, as you suggested. --mglg_(talk) 17:48, 25 February 2008 (UTC)[reply]

How did water form?

I am curious about how water originaly formed. If you filled a room with hydrogen and oxygen, would water form? What process gave us water? —Preceding unsigned comment added by 75.145.213.217 (talk) 04:03, 23 February 2008 (UTC)[reply]

You can have hydrogen and oxygen in the same atmosphere in stable molecules without them becoming water. The process by which the two elements would combine into water molecules is fire. The dirigible Hindenburg was filled with hydrogen; when it leaked, sparks possibly from static electricity began the process of combining that hydrogen with oxygen in the air. Humanity ensued. Helium is generally used in dirigibles now for this reason. Faithfully, Deltopia (talk) 04:10, 23 February 2008 (UTC)[reply]

If you filled a room with hydrogen and oxygen, it would form water, but it would take a really long time (until someone sets it off). The original water probably formed from its base elements hydrogen and oxygen, the former being found naturally after the big bang, and the latter being naturally formed in stars. Someguy1221 (talk) 10:31, 23 February 2008 (UTC)[reply]

Does that mean there could be water in the stars? —Preceding unsigned comment added by 75.145.213.217 (talk) 18:49, 23 February 2008 (UTC)[reply]

its important to note that atomic H and O are far more reactive then H2 gas and O2 gas. H2O can be split into H and O (see Water_splitting, which immediately form H2 and O2 gas. They don't form H2O again because of physical separation. H2 and O2 in a room under ambient conditions won't ever proceed to form H2O, its not thermodynamically viable. Presumably then H2O formed way back when stars were exploding and that sort of thing, around the same time all the other compounds found in the atmosphere and in the earths crust formed. 131.111.236.124 (talk) 19:22, 23 February 2008 (UTC)[reply]

The reaction doesn't proceed because it's not kinetically viable (it is too slow). Thus the need for a spark. And there is no requirement for free H and O to immediately form their diatomic gasses. Remember that these would have been randomly distributed in stellar and interstellar gasses until they cool down enough to sustain a bond to another atom, and at that state they would happily react with just about any atoms they bump into. Someguy1221 (talk) 22:18, 23 February 2008 (UTC)[reply]

There's some water on the sun, but not the way you might think. 'Cool' areas in and above sunspots – 'cool' being 3200 kelvin – have been shown to contain some water vapour: [13]. On the rest of the sun, the atmosphere is too hot for water molecules to remain intact; they would dissociate into their constituent hydrogen and oxygen atoms. TenOfAllTrades(talk) 16:20, 24 February 2008 (UTC)[reply]

Water on our planet came from volcanoes. Volcanoes produce tremendous amounts of steam. Steam is of course, water in gas form. 64.236.121.129 (talk) 17:26, 25 February 2008 (UTC)[reply]

No, most of the water still on Earth today was probably brought by comets and other impactors. See: Origin of water on Earth. Someguy1221 (talk) 00:13, 27 February 2008 (UTC)[reply]

Solving scrodinger equation for particle in a potential well

A particle in spherical shell which is chopped off from top to form a bowl like structure.potential outside the shell is infinite and inside is 0.

i.e. V=0 for     Rin<r<Rout    and      (some angle less then pi/2) < theta <pi
     V=infinity everywhere else .

Is the analytic solution for the above problem known? If yes then what is it? If no how to approach solving such a problem computationally? —Preceding unsigned comment added by 202.68.145.230 (talk) 17:50, 23 February 2008 (UTC)[reply]

It's well known. See Particle_in_a_spherically_symmetric_potential#Sphere_with_infinite_square_potential. JohnAspinall (talk) 19:31, 23 February 2008 (UTC)[reply]

Oops, I didn't read your question carefully enough the first time. The angular limits make it non-spherically symmetric. Since you still have cylindrical symmetry, I would take a first crack at separation_of_variables to get the angular part out. (Note, the cylindrical angle is not your theta.) Then you have 2 dimensional problem in R and theta, or you could go back to R and Z. That funny shaped potential looks like a job for numerical computation. See the Dongarra reference at the end of the Eigenvalue_%28quantum_mechanics%29 article. JohnAspinall (talk) 20:07, 23 February 2008 (UTC)[reply]

Strange sun halo

Hi. I see sun and moon halos all the time, but this one I found rather unusual. As a cirocumulus-cirrostratus cloud was moving in front of the sun, there was a patch of colour in the cloud, about 10 degrees away from the sun. Now, the patch extended from my hand which was covering the sun to the edge of the cloud, about 5 degrees. At first I noticed teal and pink, and then some purple, orange, and blue. Each patch was a few degrees wide. What is this type of phenomenon called? What about when the sun causes a nearby cloud about 10 deg to turn red, orange, or yellow? Oh! There it is again. A cirrostratus-cirrocumulus clouds moved near the sun. About ten degrees from the sun is reddish-orange, about 15-35 deg from the sun is pink and teal, pink patches about 8 deg wide and teal about 3 deg wide. There are also some dark creases in the cloud, 45 deg long. The orange-red part is oranger near the sun and redder farther away, orange about 3 deg wide, red about 5 deg wide.Well, the cloud is moving away. That's weird, instead of a vertical crease now there is a horizontal crease, 25 deg long, and a vertical crease nearby, about 35 deg long. Now the red-orange portion is about 7 deg wide, with a hint of yellow nearest the sun. Going farther away from the sun, the red is followed by magenta, purple, teal, and pink. Now the edges of the cloud appear with some green and pink patches, but also some purple-magenta-pink patches, about 35 deg from the sun. Too bad I don't have my camera, but even if I did, it might not be able to photograph such bright objects, or pick up colour that well. Now the colours only extend faintly about 40 deg from the sun. The orange portion dominates the 10 deg from the sun, is much brighter than the others. Going from the sun, alternating yellow, orange, red, purple. teal, orange-pink, teal-green, magenta-purple, now ends about 30 deg from sun. Teal more common at the outside, pink-magenta more common in the inside of the thin cloud. The halo-like portion of orange lies about 8 deg from sun. Now I see a complete halo, going from the sun: yellow, orange, magenta, purple, blue, teal, green, yellow, orange, red-magenta, starting at the sun and ending about 15 deg from it. The patches look like fish scales! After that 15 deg, there is some alternating pink-magenta and teal extending some 20 deg from sun. The sun itelf is surrounded by a beautiful halo in the cirrostratus-cirrocumulus cloud. There is now some faint purple in the creases, extending about 30 deg from sun. Around 10 deg of the sun, there is now some blue and purple joining the teal and pink. The pink and teal around 10 deg of the sun is now more prominent than the orange. In fact, the pink and teal seems to form a broken halo, 10 deg from sun. It is about 2 deg wide, individual patches about half a deg wide, and some orange joining the mix. The colours are gading, the cloud turning more cirrostratus-like, and a stratocumulus lies nearby. There are still remnants of the orange-red-yellow halo returning, a mere 5 deg from the sun extending to 15 deg. Well, have you any ideas what this phenomenon might be? I'm not going to describe anymore for now, but the cirrocumulus is returning, and the initial orange-red halo I described is returning, from the sun itelf to about 15 deg. The teal-pink patches are fading, and the colours extend no more than 20 deg from the sun. As the thinner cirrocumulus comes by, the teal-pink is almost invisible, and the original thick halo I described earlier is back, now green-yellow-orange-red-magenta-blue-teal-orange-red, going from the sun, each colour less than a degree wide. Any ideas what all these are? Thanks. ~A H 1^(TCU) 17:52, 23 February 2008 (UTC)[reply]

Now some updates. A cirrus cloud has moved in nearby. About 35 deg from the sun, a rainbow-like arc has formed, about 3 deg wide and long. Some blue and purple, as well as the earlier fish scales, are joining the halo near the sun. The rainbow arc, which was red closer to the sun and blue farther from the sun, is dissapearing as cirrocumulus replace cirrus in the reigon. Near the edge of a large cirrocumulus-cirrostratus cloud near the sun, there is red and orange, as well as some teal, about 3 deg wide. Earlier the cirrus coupled with cirrostratus near the sun resulted in some purple. Now there is yellow, orange, green, blue, purple, teal, and orange, going out from the sun, from the sun to about 15 deg. Earlier there was also a large gap where cirrostratus was changing to cirrocumulus, the gap ovular and 70 deg wide, with cirrus on one edge of the gap and cirrocumulus on either side. Any ideas what these phenomena are? I'm rather familiar with the rainbow-like arc, but all these were so beautiful! Thanks. ~A H 1^(TCU) 18:08, 23 February 2008 (UTC)[reply]

See sun dog.--Shantavira|^{feed me} 18:12, 23 February 2008 (UTC)[reply]

Hi. The sun dog explains what I saw in the cirrus, but not what I saw in the cirrostratus and cirrocumulus. Is the halo nearest the sun an 8deg halo? What about the teal-pink "fish scales"? Should I paraphrase my earlier posts? Now there is still a halo 8deg from sun, and in the blue-teal reigon there are "fish scales", and farther out there is pink. A blue-purple reigon touches the orange reigon farther inside. Is it known as an 8deg halo, and is there an article about the irredescence in the clouds? Thanks. ~A H 1^(TCU) 18:45, 23 February 2008 (UTC)[reply]

No pictures? Sancho 06:49, 24 February 2008 (UTC)[reply]

I didn't have my camera :-( . Is it possible to visualise it from my descriptions? The rarity of this is that it actually occured as I was typing originally to ask about a previous similar phenomenon. Thanks. ~A H 1^(TCU) 23:51, 25 February 2008 (UTC)[reply]

are silicone implants safe?

are they? . --Cosmic girl (talk) 17:55, 23 February 2008 (UTC)[reply]

Consult with your doctor; every surgery is associated with some sort of risk. You may also wish to read Breast_implant#Claims_of_Systemic_illness_and_disease and Breast_implant#Complications.--The Fat Man Who Never Came Back (talk) 18:01, 23 February 2008 (UTC)[reply]

Also consider the aesthetic difference between a cleavage and a Silicon Valley. --Cookatoo.ergo.ZooM (talk) 01:27, 24 February 2008 (UTC)[reply]

Can glasses induce oil secretions?

I've been wearing glasses for about two years now. I've noticed that every time I put them on, my nose and forehead become very, very, oily in about an hour or two. When I take them off, wash my face, and don't put them on for another hour, the oil stops coming.

I wash my face twice a day. What is it that causes the oil to keep coming only when I wear glasses? --~~MusicalConnoisseur~~ Got Classical? 20:24, 23 February 2008 (UTC)[reply]

I suppose some type of irritation could have that effect, but I'd guess it's more likely you just notice the oil more when it collects under the nose pieces of the glasses. One hint, if you reduce your consumption of fats, your skin will be less greasy. This can also lead to a healthier diet. The rate at which the skin can produce oil is dependent upon it's supply of constituents, such as lipids and fatty acids, via the bloodstream, after digestion, to the sebaceous glands. I don't suggest a fat-free diet in general, but you might want to try it for one week just to see the effect is has on your skin. Then you can go back to a low-fat (but not fat-free) diet. StuRat (talk) 21:41, 24 February 2008 (UTC)[reply]

Also, washing your face excessively might exasperate the problem. Try taking it easier on your skin (especially if you're washing with plain old soap) and see if it improves. You may also want to try an impromptu experiment on yourself - every time your face gets greasy, go wash your face. Toss a coin, and if it's heads (H), put your glasses back on after you wash your face. If it's tails (T), don't. Wait an hour (or two hours or some other predefined interval) and in either case, note whether you have had another grease outbreak (Y,N). If Y divided by H is much greater than Y divided by T, your glasses are to blame. Sockatume (talk) 02:06, 25 February 2008 (UTC)[reply]

Psychosomatic effects? :D\=< (talk) 14:06, 25 February 2008 (UTC)[reply]

I can't believe I actually have an idea here. Maybe you unconsciously wipe your forehead when your glasses are not there in the way. --Milkbreath (talk) 17:33, 25 February 2008 (UTC)[reply]

You might also subconsciously do so (when you are awake). :-) StuRat (talk) 02:34, 26 February 2008 (UTC)[reply]

See this. --Milkbreath (talk) 17:26, 26 February 2008 (UTC)[reply]

It's evolutionary. When ancient man wore glasses, he put forehead oil on the lenses so they would shed water. He also used nose grease to get rid of the head of foam on his beer. Neither of these were very practical later on, so they phased out - along with stopping a car with one's feet. 206.252.74.48 (talk) 17:11, 26 February 2008 (UTC)[reply]

tissue

what is c tissue and its purpose —Preceding unsigned comment added by Pearson 25 (talk • contribs) 21:24, 23 February 2008 (UTC)[reply]

Perhaps you could give us some context? (EhJJ)^TALK 01:04, 24 February 2008 (UTC)[reply]

Monday's homework assignment, question 3, "What is C tissue and its purpose?". ;) Sockatume (talk) 02:07, 25 February 2008 (UTC)[reply]

Connective tissue? Graeme Bartlett (talk) 12:29, 25 February 2008 (UTC)[reply]

A kind of gambling machine

There's a kind of gambling machine which is composed of:

A glass box;
With a small table inside;
When you drop a coin, the coin goes into the pile of coins on the table;
A mechanical arm sweeps the table surface over and over;
Once in a while, some coins fall off the edge and;
A lucky guy gets rich.

What is the name of this gambling machine?

If the casino owner keeps the machine untouched, in the very long run, the expected value of the game shall be 1. You drop 1 coin in and you get 1 coin back. The only way a casino owner makes money is to harvest some coins periodically.

Then, can a casino owner harvest money as frequently as possible to increase his profit?

In most countries that allows gambling, gambling is still highly regulated. Then how does the government regulate this kind of gambling? You know the house's advantages for most gamblings. However, this kind of gambling really cannnot be regulated because the owner can harvest coins hourly.

How could a sucker play it if he sees the owner open the box and take some coins out?

Then how does the owner make money without making these suckers unhappy? -- Toytoy (talk) 21:29, 23 February 2008 (UTC)[reply]

I don't know for sure, but would speculate that there is a hole somewhere which allows some of the coins/tokens/chips to drop into a collection basket for the owner. In the long term you could calculate the percentage take this will generate, which could, of course, be manipulated by the size and location of the hole(s). StuRat (talk) 21:44, 23 February 2008 (UTC)[reply]

The machine is called a "Penny Pusher" or "Penny Cascade" or possibly "Penny Fountain" (although this last term is also applied to other machines as well). The operator never harvests the coins on the table. The house cut comes from a percentage of coins falling through small holes at the side of the table. They hope you won't notice these of course. SpinningSpark 22:06, 23 February 2008 (UTC)[reply]

Small nitpick: if the probability of earning money is equal to the probability of losing the same amount of money, the expected value is 0, not 1. --Bowlhover (talk) 04:44, 24 February 2008 (UTC)[reply]

"Penny Falls" is another name for it. --Heron (talk) 16:31, 24 February 2008 (UTC)[reply]

Sometimes it eats your money without letting it drop to the moving shelf. You could harvest after closing time (assuming it's not a 24-hour casino, otherwise harvest when it's quiet). Sometimes the shelf has extra prizes on top (like a note or bag of coins), so it's obvious the machines aren't left to themselves. (Disclaimer: this is all OR or speculation) AlmostReadytoFly (talk) 09:47, 25 February 2008 (UTC)[reply]

Grapefruit seeds

I've noticed something odd about grapefruit seeds, at least for Ruby Reds (I avoid those bitter white grapefruit): they have two distinct seed sizes within each grapefruit. There are many tiny seeds, and just a few large seeds (often less than one per section), but never any medium-sized seeds. So, why is this ? My own guess is that the large seeds are fertilized and the small ones are not, which causes their growth to stop early on. StuRat (talk) 21:38, 23 February 2008 (UTC)[reply]

One possible reason is it is triploid. For example, if there are three chromosomes AAA,BBB,CCC after meiosis the gametes (pollen or egg) can have either one or two of each chromosome. Rarely an A,B,C or AA,BB,CC pollen grain will fertilise an A,B,C or AA,BB,CC egg. Thus a seed will be produced as the chromosomes are balanced (a diploid, triploid or tetraploid seed are produced). Usually the chromosomes are unbalanced and those seed are infertile. This is the basis for most seedless varieties. Note that as the number of chromosmes increases there is less chance of a seed. The best I could find in wikipedia is at Seedless fruit, but it does not really address the genetics yet. Something for a to-do-list. David D. (Talk) 04:50, 24 February 2008 (UTC)[reply]

Thanks for the reply. So it looks like I was correct in thinking it was related to whether the seed is fertile or not. StuRat (talk) 05:51, 24 February 2008 (UTC)[reply]

Yes. Sorry, the above was the long winded answer that is plausible, but note it is speculation. I don't know if the grapefruit you are talking about is triploid or not. David D. (Talk) 18:32, 24 February 2008 (UTC)[reply]

Might have something to do with whether the seed was from self-fertilized flowers or crossed ones. With mandarins grown with one variety per paddock, the trees close to the edge have the fruit with lots of seeds; whereas the trees in the middle of the paddock have few or no seeds. Haven't checked the seed sizes though. Polypipe Wrangler (talk) 07:23, 28 February 2008 (UTC)[reply]

Why would the seed size vary depending on whether self-fertilized or cross-fertilized ? In this case the two different size seeds occur within the same grapefruit, which I believe comes from a single flower. It is possible for one flower to be both self-fertilized and cross-fertilized by others, though, I suppose. StuRat (talk) 13:35, 28 February 2008 (UTC)[reply]

Since you are interested, here is more detail. I did a search with keywords citrus fertilization grapefruit.

It turns out that polyembryony occurs, with some seeds formed from fertilization (the usual process) and some seeds formed from the mother trees tissue in the fruit. Those seeds are clones of the mother tree. I remember reading that this process (embryogenesis) can be encouraged in plant tissue culture to get seedlings that are clones; used to get healthy copies of trees which are hard to take cuttings from.Polypipe Wrangler (talk) 21:36, 28 February 2008 (UTC)[reply]

February 24

Here comes the sun

I have read the wikipedia article on that great celestial body, but I did not found the information I seek.

If the sun is mostly mad up of gases and plasma--how does it have as much mass as it does? That is, gases and plasma are not very dense in my understanding, and yet the sun has enough mass to keep the entire solar system in check. What am I missing, or is merely a case of "yes, gases have a low density, but there's just so damn much of it!" —Preceding unsigned comment added by 192.136.22.4 (talk) 02:23, 24 February 2008 (UTC)[reply]

It's a matter of mass in terms of quantity (of gas/plasma molecules) and the size of the star, but also the fact that the core is dense. Wisdom89 _{(_T / ^C)} 02:28, 24 February 2008 (UTC)[reply]

Gasses do not have to have low density. This perception results merely from the tendency of gasses on Earth to have low density. At extremely high temperatures and pressures, gas can be incredibly dense. Indeed, the average density of the sun is greater than that of water (density of water is about one gram per cubic centimeter), although the precise value of density depends on distance from the center. At the core itself, the density of the sun is an incredible 160 grams per cubic centimeter, which is much denser than even solid metals (uranium, denser than even lead, has a density of only 19 grams per cubic centimeter). Once again, these densities are possible in the sun due to extreme temperatures and pressures. Someguy1221 (talk) 02:57, 24 February 2008 (UTC)[reply]

It's also partially a matter of "there's just so damn much of it". If you add the volumes of the planets, you'd get 2.39 x 10^15 m^3. By comparison, the Sun's volume is 1.4122 x 10^18 m^3, about 600 times larger. --Bowlhover (talk) 04:15, 24 February 2008 (UTC)[reply]

The sun is approximately on average 1.4g/cm³, about 108 Earth diameters, and you probably didn't need to know any of that because you could probably find it in the article and I'm probably innacurate anyway. Hope this helps. Thanks. ~A H 1^(TCU) 00:42, 26 February 2008 (UTC)[reply]

Breitling Orbiter 3

Hello. The world's first round-the-world balloon flight was on March 1, 1999. Couldn't the flight take place during the summer so that Chateau d'Oex becomes closer to the jet stream? Thanks in advance. --Mayfare (talk) 05:18, 24 February 2008 (UTC)[reply]

Human genome conservation with dogs

Does anyone know how conserved the human genome when compared to the dog genome? I should know how to do this, but for the life of me I can't remember how to use NCBI's website to do a genome comparison. Anyknow know how genetically similar we are compared to dogs?

According to this source, dogs share 95% of their genes with humans.[14] MrRedact (talk) 07:13, 24 February 2008 (UTC)[reply]

Haha, is it actually true that we share 50% of our DNA with bananas? That's wonderfully absurd if true, although I have to admit, I have no clue what it means at the moment. -- Aeluwas (talk) 12:54, 24 February 2008 (UTC)[reply]

I find that 50% human/banana overlap apeeling. Edison (talk) 13:55, 24 February 2008 (UTC)[reply]

"In Tahiti an old Polynesian chief explained his diet: 'The white man, when well roasted tastes like ripe banana.'"Vintage School 4.1. There you are! Pro bug catcher (talk • contribs). 14:47, 24 February 2008 (UTC)[reply]

Which of your parents is it, that you claim is descended from a banana? (apologies to Sam Wilberforce). SpinningSpark 20:31, 24 February 2008 (UTC)[reply]

Oh, the painful punniness of it all. Yes, we share a large amount of our DNA with other eukaryote (and even quite a bit with prokaryotes. At the molecular level or proteins and lipids and whatnot, we're really strikingly similar. Yes, even with plants. – Clockwork Soul 21:49, 25 February 2008 (UTC)[reply]

RNA amplification

I know you use PCR to amplify DNA, is there a process similar to PCR which you can use to amplify RNA? —Preceding unsigned comment added by 70.49.175.36 (talk) 06:04, 24 February 2008 (UTC)[reply]

RTPCR. — Scientizzle 06:51, 24 February 2008 (UTC)[reply]

Question about Salmon (but don't Rushdie answer)

Salmon die shortly after mating, but what is the exact mechanism of this death ? Does their immune system shut down, allowing disease to finish them off ? StuRat (talk) 06:38, 24 February 2008 (UTC)[reply]

Their swim upriver drains their fat stores and generally exhausts them, leaving them open to injury, disease, or parasitism. The "after spawning" section of this article notes that they don't all die, and those (few) that manage to survive can return to nominal health and even spawn again. -- 19:23, 24 February 2008 (UTC) —Preceding unsigned comment added by Finlay McWalter (talk • contribs)

Thanks, that article seems to say that male Atlantic salmon die because they remain in the spawning area to mate repeatedly, draining their energy stores until they die, but that many females do survive. It didn't really talk about Pacific salmon, though, other than to imply that they all die. Do we know what causes this ? The Chinook_salmon#Reproduction section seems to say that they die because they stay around to "guard the eggs", until they die. Is this true of all Pacific salmon ? StuRat (talk) 20:33, 24 February 2008 (UTC)[reply]

Ha ha, funny heading title. My compliments. —Lowellian (reply) 19:28, 24 February 2008 (UTC)[reply]

Thanks. :-) StuRat (talk) 20:33, 24 February 2008 (UTC)[reply]

Pacific salmon certainly don't "guard the eggs". All Pacific Salmon, I believe, die shortly after spawning--it's a sort of built-in death. There is an interesting article [15] that sees some similarities between this and Alzheimers.--Eriastrum (talk) 21:24, 24 February 2008 (UTC)[reply]

That article is quite useful, thanks. It looks like the process isn't yet completely understood. Is the statement "After laying eggs in a redd, adult Chinook will guard the redd from 4 to 25 days before dying." incorrect in our article: Chinook_salmon#Reproduction ? Perhaps it should say "remain in" instead of "guard" ? StuRat (talk) 23:29, 24 February 2008 (UTC)[reply]

I think that the female guards the redd until she lays the eggs and the male fertilizes it. Then she goes on to make another redd. I thus don't think that it is correct to say that she guards the eggs as such. I can't vouch for its accuracy, but this article seems to have relevant information [16]. Maybe salmon aren't fat(wa) enough to live longer (sorry).--Eriastrum (talk) 00:42, 25 February 2008 (UTC)[reply]

Thanks, but that article did seem to say the females guard the redd, but not the males. Iran directly to our article to make the correction. StuRat (talk) 01:50, 25 February 2008 (UTC)[reply]

Photon bouncing?

Inspired by this, if we have 2 identical space ships with perfect reflectors on the back going on opposite directions, and one shoots a beam of laser to the other one, what will eventually happen to the photon? What happens when it gets so red-shifted that it's no longer stable (there is a lower bound on its frequency right?)? --antilived^{T | C | G} 07:38, 24 February 2008 (UTC)[reply]

Hmm, why do you think red-shifting will eventually make the photon unstable? There is no lower bound to frequency and if the reflectors are perfect as you specify and the transmission medium is perfect it will bounce back and forth forever.

Of couse, in practical terms there are any number of things that could eventually lose a given photon out of the system. If nothing else, it would eventually be red-shifted so far that the wavelength is large compared to the size of the reflector and will then fail to be reflected and carry straight on past the space ship. However, your space ship will probably have broken down and decayed long before then. SpinningSpark 12:14, 24 February 2008 (UTC)[reply]

So there is no lower bound on the frequency? Can a photon with the wavelength of more than the universe exist? --antilived^{T | C | G} 05:58, 25 February 2008 (UTC)[reply]

There is no limit, not up not down. There can't be - it would violate conservation of energy. But with a wavelength below the Planck length it is not calculable using current physics. The universe does not have a fixed size. Even if it's bounded, it would probably wrap around, so a photon could be as big as it wants. It 'feels' like it should have some weird properties when it's so big, but I can't think of any. Perhaps the uncertainty principle would do something strange to it. Ariel. (talk) 12:52, 25 February 2008 (UTC)[reply]

Bit shaky on my quantum mechanics (its been a long time) but I would guess a photon that was that big would be experiencing destructive interference as in DeBroglie wavefunctions for an electron in a Hydrogen atom. That is, it can only exist if it is exactly the right size or a harmonic. Ariel is right that there is no limit in free space, but in a bounded situation everything becomes quantized because of standing waves in the wavefunction. Or possibly I am just talking unsubstantiated OR, I have never seen anything written on photons that big. SpinningSpark 14:01, 25 February 2008 (UTC)[reply]

Boiling oil

what happens when you boil oil? The Updater would like to talk to you! 11:04, 24 February 2008 (UTC)[reply]

I'm not sure I understand the question. Obviously, when you boil anything it transitions from a liquid to a gas, but I suspect your question is about something specific about oil. StuRat (talk) 14:40, 24 February 2008 (UTC)[reply]

Also, what kind of oil? Motor oil, cooking oil, sewing machine oil? Delmlsfan (talk) 15:27, 24 February 2008 (UTC)[reply]

Howstuffworks has a nice illustration of the range of boiling points for petroleum products. Note also that, in a standard atmosphere, most oils begin to burn well below their boiling points. — Lomn 15:49, 24 February 2008 (UTC)[reply]

Too bad that isn't true of cooking oils. That might prevent us from frying our food in it. :-) StuRat (talk) 20:19, 24 February 2008 (UTC)[reply]

That is true of cooking oils—deep fryers are used at temperatures well below the boiling point of most edible oils. (The key criterion in choosing an oil for deep frying is the oil's smoke point; boiling point is never considered.) TenOfAllTrades(talk) 23:47, 24 February 2008 (UTC)[reply]

Then there must be a great deal of confusion among chefs, since I found 728 Google hits, most of which appear to be recipes that instruct the cook to bring oil to a boil: [17]. StuRat (talk) 01:35, 25 February 2008 (UTC)[reply]

I don't think it's so much confusion among chefs as it is confusion among idiot web page authors. Chefs (and cooks with even a modicum of common sense) are well aware that oil is not boiled in cooking. That, in fact, is one of the dangers - 350°F oil is visually indistinguishable from room temperature stuff. The confusion probably has roots in water's well-known and much lower boiling point, which comes into play when food is added to the fryer -- any water present quickly boils, which is responsible for all the hissing, popping, and so forth. — Lomn 14:24, 25 February 2008 (UTC)[reply]

But most of the directions say something like "bring the oil to a boil, then add the food", so what would make them think the oil was boiling before the food has been added ? StuRat (talk) 02:28, 26 February 2008 (UTC)[reply]

Objectively? Nothing. Absolutely nothing suggests that 350°F oil would be "boiling" except for the possibility that somebody says "350? That would boil water! OK, then, 'boiling'!" (Never mind, of course, that water can't hit 350°F either). Thus, I'm blaming the web page author, or perhaps more appropriately should blame people who don't understand "boiling". Note, for instance, specifically phrased Google hits: "heat oil to a boil" gets 3, "bring oil to a boil" gets 12, and "heat oil to 350" gets 586. The vast majority of cooks understand that oil is not boiled when cooking. — Lomn 14:30, 26 February 2008 (UTC)[reply]

I clicked on your link for "bring oil to a boil" and got 703 hits, not 12. (I've asked before about why different people get radically different Google results when doing the same search, but never did get a satisfactory answer.) The recipes are often for cooking on the stove, and no temperature is mentioned, so they must be instructing people to heat the oil until something visible happens that can at least be confused with boiling. StuRat (talk) 05:51, 27 February 2008 (UTC)[reply]

Perhaps it's a matter of making sure you've counted all actual results? I run Google with 100 English-only results returned as a default, and while I list 586 returns for "heat to 350", Google's initial estimate for that query is 11.3 million. However, the bit about the oven is what I addressed above regarding the dangers of oil: until you reach the smoke point (often around 400°F for cooking oil, at which point it is chemically breaking down and worthless for cooking) there is no obvious distinguishing visible factor. Hot oil displays miniscule ripples (which I think are actually atmospheric distortions from the heat, not actual surface displacements in the oil), but we're talking about something with an apparent displacement of less than a millimeter and relatively static. Nothing at all about hot oil resembles boiling water in any way until you add water to the pot. — Lomn 14:23, 27 February 2008 (UTC)[reply]

Perhaps your question is about spattering of cooking oil when food is poured in. This can happen if there is water or ice on the food, which then turns into steam and can launch droplets of oil out of the pan with it. To prevent this, make sure the food is dry before you place it in boiling oil. Splashing of the oil is also possible if food is dropped in. To prevent this, slowly lower food into boiling oil with a fry basket. StuRat (talk) 20:56, 24 February 2008 (UTC)[reply]

WikiProject Reference Desk Article Collaboration

This question inspired an article to be created or enhanced:

Early thermal weapons

Please consider contributing

Of course, in the popular mind, boiling oil is associated with medieval siege defence. Despite what you might read there, or in a lot of websites or books, boiling oil was not used for this purpose. Crude oil was used in Greek fire, and the Romans were known to have used hot oil on a few occasions (but it was not very common). The main use of murder holes was boiling water: easier than oil, cheaper, less dangerous, more plentiful, very effective. I think the popular mind has just merged "boiling water" with "oil", a situation not helped by a few Hollywood movies. -Gwinva (talk) 01:03, 25 February 2008 (UTC)[reply]

Apologies if it's impolite to add on to someone else's question, but is it true that lime was also used? AlmostReadytoFly (talk) 09:27, 25 February 2008 (UTC)[reply]

Yes. I'll hunt the details out if you're interested. Gwinva (talk) 09:29, 25 February 2008 (UTC)[reply]

Thanks, but no. It's enough that I know I hadn't imagined reading that somewhere. AlmostReadytoFly (talk) 10:41, 25 February 2008 (UTC)[reply]

Shouldn't that article be updated to say that oil doesn't actually boil? :D\=< (talk) 17:17, 25 February 2008 (UTC)[reply]

Yes, so I've done it by moving it to Early thermal weapons (since I couldn't think of a better title), ditching most of it then rewriting with the stuff about sand, water, quicklime etc. If any of you science buffs can add a reference for the smoke point of oil being lower than boiling point, that would be great (otherwise someone is bound to cn-tag it at some point!). Gwinva (talk) 00:30, 26 February 2008 (UTC)[reply]

One product produced is Acrolein contained in the smell of burnt fat. Graeme Bartlett (talk) 12:25, 25 February 2008 (UTC)[reply]

Salinity of saline solutions

How salty are sweat, tears and that stuff that you use to soak your contact lenses compared to, like, the ocean?--The Fat Man Who Never Came Back (talk) 15:09, 24 February 2008 (UTC)[reply]

The salinity of sweat is examined in this paper by Bulmer and Forwell. It depends on the sweat rate, but seems to be between 30 and 120 molar equivalents per litre. Sancho 15:23, 24 February 2008 (UTC)[reply]

The salinity of seawater is about 3.5%. Most of that's sodium chloride. Tears have the same osmolality as the body's internal fluids, containing a mixture of salts. (An isoosmotic solution of sodium chloride – as used in normal medical saline solution – contains about 0.9% sodium chloride: about 150 millimolar.) TenOfAllTrades(talk) 17:13, 24 February 2008 (UTC)[reply]

salinity of bodily fluids is the same as the salinity the ocean was, when our distant ancestors crawled out of it; they had to carry that environment around with them for their cells to function. meanwhile, however, the earth continued to wash minerals down off the land into the ocean, so that now it is much saltier than it was then, and than we are; and the organisms that stayed behind have had to adapt to that.Gzuckier (talk) 18:27, 26 February 2008 (UTC)[reply]

The same as when our ancestors crawled out of the ocean? Are you sure? Wouldn't it be more likely to be the same as when cellular life forms established a clear separation between what was inside and what was outside the cell, i.e. some two billion instead of 500 million years ago? Or possibly when multicellular life evolved? See Timeline of evolution. I was unable to find any source internally or externally about rate at which ocean salinity has risen. Is anything known at all on such large time scales? --NorwegianBlue^talk 20:41, 26 February 2008 (UTC)[reply]

Thank you. And now for another salty question....

Other salts

Do all salts taste "salty?" Are there any edible, nutritious salts besides NaCl?--The Fat Man Who Never Came Back (talk) 17:49, 24 February 2008 (UTC)[reply]

'Nutritious' is a matter of quantity. Chronic excess consumption of sodium chloride is linked to high blood pressure, heart disease, and other ailments. Acute overdoses of sodium chloride can be fatal.

To answer the question you're probably asking, potassium chloride is often used as a salt substitute for individuals on sodium-restricted diets. Its oral toxicity is quite low (comparable to that of sodium chloride). TenOfAllTrades(talk) 17:56, 24 February 2008 (UTC)[reply]

What are the most toxic salts? Are they salty as well?--The Fat Man Who Never Came Back (talk) 18:01, 24 February 2008 (UTC)[reply]

You'll have to test and report back.

On a somewhat more serious note, there are a lot of different salts, and they will have a wide range of tastes. Salts of zinc reportedly have a bitter, astringent flavour. Cyanide salts have an odour of almonds—tasting is discouraged. Calcium carbonate is the bulk of most calcium antacids; it has a chalky taste. Sodium citrate is acidic and tart. Alkaline salts may have a soapy taste or mouthfeel. The list is practically endless. TenOfAllTrades(talk) 19:24, 24 February 2008 (UTC)[reply]

Also see Taste#Saltiness, which could use references. --Allen (talk) 20:19, 24 February 2008 (UTC)[reply]

I stumbled upon a paper on this subject recently, but I'll be damned if I can remember what keywords I was searching the journals with. If I recall, it's the chloride anion which actually triggers the "salty" flavour, and different counterions (sodium, potassium, etc.) affect how strongly salty something may taste. If I find the article, I'll get back to you. Sockatume (talk) 01:37, 25 February 2008 (UTC)[reply]

check out Sea Salt. That tends to have all kinds of salts mixed up in it. Furmanj (talk) 01:54, 25 February 2008 (UTC)[reply]

Also check out Salt (chemistry)#Tastes. Sockatume: from personal experience, potassium chloride tastes much saltier than sodium chloride and has a very unpleasant aftertaste. Calcium carbonate has no taste. Potassium nitrate, the main component in gunpowder, tastes slightly alkaline. Sodium bicarbonate, baking soda, also tastes alkaline and sodium carbonate is unbearably so. Lithium oxide turns into lithium hydroxide upon contacting water, and therefore tastes very caustic. Iron oxide is obviously tasteless. Again, all of this is from personal experience and may not be reliable. --Bowlhover (talk) 06:42, 25 February 2008 (UTC)[reply]

Other edible salts include Epsom salts and sal ammoniac. Magnesium chloride tastes more salty than salt, and Calcium chloride is pretty harmless. potassium sulphate and sodium sulphate taste less salty but are also harmless in small quantities. PS don't eat lithium oxide or lithium hydroxide as they are very damaging to flesh. Graeme Bartlett (talk) 12:18, 25 February 2008 (UTC)[reply]

Yes, don't eat sodium carbonate either. It is used as washing soda and tastes extremely, extremely alkaline. --Bowlhover (talk) 17:26, 26 February 2008 (UTC)[reply]

That is superb--tasting notes for salts of every sort. I love the Science reference desk.--The Fat Man Who Never Came Back (talk) 02:21, 26 February 2008 (UTC)[reply]

There was an episode of Good Eats that focused on salt, it aired back in 2004. Alton Brown talked about all the different kinds of salts depending on where they come from, how they're processed, etc... -- MacAddct  1984 ^{(talk  contribs)} 15:03, 25 February 2008 (UTC)[reply]

I love Alton Brown. But I'm sure he was talking about different kinds of table salt. I was asking about different types of chemical salts.--The Fat Man Who Never Came Back (talk) 02:21, 26 February 2008 (UTC)[reply]

See also Monosodium glutamate (MSG), also known as E621. It is used as a food additive because it stimulates the umami taste receptors. I heard a story on this podcast that suggested a link between the huge increase in the consumption of MSG and the obesity epidemic, based on studies in rats, but according to our article, this correlation was not found in humans. --NorwegianBlue^talk 22:02, 25 February 2008 (UTC)[reply]

I am confused by the claim that iron oxide is flavorless. Rusty nails taste different from plain nails, and the difference is iron oxide. Edison (talk) 05:30, 26 February 2008 (UTC)[reply]

Sorry, iron oxide is not flavourless. It has a mild taste that I can't accurately describe; it's been a long time since I've tasted rust. --Bowlhover (talk) 17:26, 26 February 2008 (UTC)[reply]

Coriolis Effect

I was reading the article on the coriolis effect, which featured the following illustration. This diagram shows that air travelling in an East-West or a West-East direction will be deflected perpendicular to their velocity. How is this possible, considering that they are travelling along the rotation of the earth? —Preceding unsigned comment added by 76.68.246.134 (talk) 18:05, 24 February 2008 (UTC)[reply]

Consider that air from all directions except due east or west are affected by the Coriolis effect. The low-pressure area draws in air from the east and west, which will then be forced to travel with the already-circulating air from other directions. --Bowlhover (talk) 06:54, 25 February 2008 (UTC)[reply]

The Coriolis effect will act perpendicular to the rotation axis of the Earth. There is a component which is parallel to the surface of the Earth, which is what is shown in the picture and what is talked about in meteorology. There is also a component which is perpendicular to the surface of the Earth, especially in low latitudes, but that is generally ignored because it is insignificant compared to other forces in that direction like gravity. --Spoon! (talk) 22:05, 25 February 2008 (UTC)[reply]

That's true but irrelevant. To understand the Coriolis effect on a spherical rotating surface, you have to think in three dimensions. What you have to remember is that any particular point of the surface is always rotating along a circular path parallel to the equator, otherwise called a parallel of latitude. Consequently the Coriolis force is felt in the plane of that path, not the plane of the local part of the surface.

At the equator itself, for example, a "stationary" object is rotating eastward at a bit over 1,000 mph. It therefore feels a certain amount of upward centrifugal force and is a bit lighter than it would be if the Earth was not rotating. If the object is set in motion eastward at 200 mph, its real total speed is now 1,200 mph and the centrifugal force is increased. This increase in centrifugal force is precisely a Coriolis force, and it is upward -- it has to be, because the Coriolis force is in the plane of rotation.

Now consider an object at say 45° north latitude, moving eastward. It also feels a Coriolis force upward -- but not straight up. It's upward parallel to the plane of the equator. In other words, the force acts at a 45° angle to the ground, angled toward the south. This is equivalent to the combination of a force straight up and another force, in this case equal, pointing south. The upward force is not important for an object that follows the ground, but the southward force makes the object deviate to the right. Similarly, an object moving westward will feel a force downward and to the north, and again will move to the right.

(For the southern hemisphere, of course, you reverse "north" and "south" in the last paragraph, and the deviation is to the left.)

--Anonymous, 08:04 UTC, February 25, 2008.

Hold on, that explanation isn't the coriolis effect. The coriolis effect has nothing at all to do with centrifugal force (that's the Eötvös effect)- it's an 'illusion' caused by looking at motion from within a rotating frame of reference. You can't really understand anything Coriolis without the Foucault Pendulum.. read the article and then, if you don't much value your sanity, gaze on the image to the right. It's screwy but completely correct. :D\=< (talk) 10:17, 25 February 2008 (UTC)[reply]

No, that is the Coriolis effect. The Eötvös effect is just a term used to describe the component of the Coriolis effect that is perpendicular to the surface of the Earth when we are talking about situations on the surface of the Earth. --Spoon! (talk) 21:53, 25 February 2008 (UTC)[reply]

I think :D\=< is right. Isn't the centrifugal force fictitious? And isn't it the coriolis effect, rather than the coriolis force. Finally, would't the effects of the centrifugal force on a latitude of 45 degreed be straight up? —Preceding unsigned comment added by 76.68.246.134 (talk) 00:22, 26 February 2008 (UTC)[reply]

Sigh. Look, the centrifugal effect and the Coriolis effect are both fictitious or illusory forces, hence their alternate names "centrifugal force" and "Coriolis force". They both are the result of viewing things from a frame of reference that is rotating. And they both can be analyzed by considering the real motions. I gave an example where this can be done simply: for an object moving along the equator, the Coriolis force is vertical and amounts to the difference between the centrifugal force on the object as it is and as it would be if it was fixed to the Earth. Think about it. And the answer to 76's last question is no. The fictitious forces depend only on which way things are moving -- not which way is up. --Anonymous, 05:25 UTC, February 26, 2008.

Thanks for correcting me, everyone. I must say I've never heard of the way centrifugal force affects weather systems. --Bowlhover (talk) 05:35, 27 February 2008 (UTC)[reply]

Moon and Sun having the same apparent size

The fact that the Moon and the Sun have almost exactly the same apparent size from Earth has always surprised me. Is it really just a coincidence? --Taraborn (talk) 20:22, 24 February 2008 (UTC)[reply]

It's variable. Remember you're seeing a halo/glow around the sun. Also, at different times during the day, depending on the relative positions, they will appear as different sizes. One is 93 million miles away, the other is like 240,000. Wisdom89 _{(_T / ^C)} 20:29, 24 February 2008 (UTC)[reply]

I'm aware of that. Actually, at the age of the dinosaurs, the Moon was quite closer to Earth than it is now. --Taraborn (talk) 18:51, 25 February 2008 (UTC)[reply]

But to answer your question, yes, I believe it is just a coincidence. It depends on the sizes of the Moon and Earth and the distances to the Moon and Earth. I don't think that all moons are the same apparent size as the Sun when viewed from the surface of their respective planets. It would be interesting to know if any of them are (although what is meant by the "surface" of the gas giants then becomes a question). StuRat (talk) 20:38, 24 February 2008 (UTC)[reply]

As Orbit of the Moon#Tidal evolution of the lunar orbit notes, the radius of the Moon's orbit is (very slowly) increasing (making the Moon appear very slightly smaller) as time goes on. That would imply that the coincidental thing is that their apparent diameters are so similar now, and that in the past the Moon appeared bigger and that in the future it will appear smaller. Unfortunately that article doesn't give figures for the past and future orbits of the Moon, so I don't know how great that change has been, or will be. -- Finlay McWalter | Talk 21:02, 24 February 2008 (UTC)[reply]

Considering how briefly humans have been on the Earth compared with the age of the solar system, I'd expect that any change in the apparent size of the Moon was and will continue to be negligible in the period when this size could be seen by humans. StuRat (talk) 21:24, 24 February 2008 (UTC)[reply]

It does imply it's just a coincidence though Nil Einne (talk) 09:24, 25 February 2008 (UTC)[reply]

File:RingfoermigeSonnenfinsternis.jpg

An annular solar eclipse

It is indeed a coincidence. Indeed, the relationship isn't even dead on. Because the orbits of the Earth and (especially) of the Moon aren't perfectly circular, a solar eclipse will sometimes occur when the Moon's apparent size is appreciably smaller than that of the Sun: an annular eclipse. —Preceding unsigned comment added by TenOfAllTrades (talk • contribs) 21:39, 24 February 2008 (UTC)[reply]

On Mars solar eclipses are much less exciting because Mar's moons are so much smaller. Transit of Phobos from Mars APL (talk) 22:11, 24 February 2008 (UTC)[reply]

Well Judaism said that the sun was originally a binary star. But the star that became the moon complained "how can you have two kings", and as punishment was reduced in size. But it was also placed a lot closer. So that the far away sun, and the nearby moon both appeared the same size, in memory of what was. Irregardless of what you think of the story, it does show that the ancients knew that the sun was a lot farther than the moon, and that the moon simply reflects the suns light. Ariel. (talk) 12:40, 25 February 2008 (UTC)[reply]

Weird Taste and Smell lingering days after taking Advil Cold and Flu

Has anyone ever heard of such a thing? This is the medicine that they now sell only after you show ID thanks to the Patriot Act and anti-bomb and meth lab stuff. So I am wondering if "they" are putting some kind of weird chemical in it now so that people won't want to use it for whatever bad purposes they were using it for. Yesterday it rained here and the air is usually so sweet and fragrant, but instead it smelled, everywhere, like chemicals you put in your pool - not chlorine, but other acrid and ... I cannot ever think of what to compare the smell to...like something you'd preserve dead things in. Lately too food seems a little off, like there is a weird metallic or chemical essence lingering on the fringes of normal flavor. The only thing I can rationally/causally relate it to is the Advil, because I didn't experience it with the nasty cherry-flavored Robitussin cough syrup I swilled for 3 days prior to obtaining the Advil. I only took the Advil on the last day of the sickness. Maybe 3 tablets in all. I feel that if the chemical smell/taste is just coming from *me* sans Advil, then I am as thoroughly pickled in chemicals as was Gloria Ramirez. I am not looking for medical advice, just to see if anyone has heard of similar anecdotes / experiences and knows how long it takes for these chemicals to leave one's body. Thanks. Saudade7 23:58, 24 February 2008 (UTC)[reply]

I believe that differences in taste and smell are side effects of some medications. I'd check the label to see if this is a listed side effect for the meds you are taking. StuRat (talk) 01:19, 25 February 2008 (UTC)[reply]

That'd be well worth checking out, but it could also be a side-effect of the cold. Infections up there can cause temporary or permanent disruptions to your ability to smell and, therefore, taste. (I really don't enjoy my food the same way in the winter these days.) If it doesn't clear up, consider going to the doctor. Sockatume (talk) 01:58, 25 February 2008 (UTC)[reply]

Thanks Sockatume and StuRat, I went out tonight and the rain smelled like...rain! But that smell was so damned weird, truly chemical. It is weird to think how little of a chemical is necessary to wig out all your sense perceptions! I was just wondering if anyone else had experienced this on Advil C&F. love, Saudade7 07:48, 25 February 2008 (UTC)[reply]

February 25

Alternate method of boiling

Would it be possible to boil food by lowering the pressure instead of raising the heat? I assume yes, but would the food produced have the same taste/texture as a conventionally boiled dish? I understand that meats need the heat to fully cook, but is the same true of rice/noodles?HYENASTE 00:27, 25 February 2008 (UTC)[reply]

Yes, you could boil food that way, but I don't think it would qualify as cooking it. I believe the cooking time is increased at high altitudes due to the reduced temp where boiling occurs (based on the lower air pressure). But, if you don't add any heat at all, I don't think you would expect any of the benefits of cooking, like killing bacteria and breaking down difficult to digest foods. StuRat (talk) 01:16, 25 February 2008 (UTC)[reply]

dry pasta needs to be both rehydrated and cooked (as opposed to fresh pasta, which still needs to be cooked). If you wet pasta and then lowered the pressure you'd simply dehydrate it (or anything else you put under vacuum). Furmanj (talk) 01:52, 25 February 2008 (UTC)[reply]

Exactly, this would be a reveres of the effect of a Pressure cooker where cooking time is reduced by increasing pressure and therefore temperature. The section Pressure cooker#Use at high altitudes is particularly relevant. -- Q Chris (talk) 11:45, 25 February 2008 (UTC)[reply]

You would boil the liquid, but the chemical changes involved in cooking pasta and rice (the breakdown of starchy grains) require the heat. Actually, you'd be more likely to freeze your food by doing this (boiling requires heat anyway, it's just that it happens more spontaneously if you lower the pressure). I've certainly hooked things up to rotary evaporators (a piece of chemistry apparatus) and developed a crust of ice on the outside through over-eager vapourising. Sockatume (talk) 01:55, 25 February 2008 (UTC)[reply]

basically, if you lower the pressure enough, it becomes freeze drying, which is not the same as cooking. Gzuckier (talk) 18:29, 26 February 2008 (UTC)[reply]

Electric Car

I'm considering getting a cheap electric car, maybe something that's been retrofitted from a gasoline-powered car. What sort of issues should I be on the lookout for? Safety, maintenance, anything that might help me find something practical. Black Carrot (talk) 00:58, 25 February 2008 (UTC)[reply]

Here are some issues:

1) Range on a full charge.

2) Acceleration.

3) Top speed.

4) Can it be recharged at home or only at certain locations ? Where are the locations near you ?

5) How long does it take to fully recharge ?

6) How long do the batteries last before they will no longer hold a charge ?

7) How much will it cost per mile to operate ?

8) How is electricity in your area generated ? If it's made by burning coal, then an electric vehicle used there won't help the environment, but if electricity comes from a nuclear plant or clean energy source, then it will help.

You might want to consider a gasoline-electric hybrid, as that is a nice compromise that can solve many of the issues that electric-only vehicles have. StuRat (talk) 01:07, 25 February 2008 (UTC)[reply]

The following articles may be useful: Electric car, Plug-in hybrid, Hybrid vehicle. MrRedact (talk) 01:25, 25 February 2008 (UTC)[reply]

Even if coal is used to generate the electricity it is likely it will still be better for the environment than an internal combustion engine. Electric motors are generally much more efficient than ICE's. Pollution is not in the city thus less smog. CO2 Emissions however would probably be about the same (guess).Shniken1 (talk) 03:06, 25 February 2008 (UTC)[reply]

But don't forget about the inefficiency due to electrical losses in the power lines and during storage in the batteries. StuRat (talk) 03:38, 25 February 2008 (UTC)[reply]

I haven't done the sums, but I suspect Shniken1 is right. Internal combustion engines are just utterly crap when it comes to efficiency and it is very difficult to limit the pollution from a vehicle. According to Electric power transmission, in the US average losses in transmission and distribution is only 7.2%. And don't forget something like a petrol-electric hybrid will suffer some of the same losses due to storage anyway Nil Einne (talk) 09:19, 25 February 2008 (UTC)[reply]

OK, but don't forget to add the energy loss from the charging procedure, energy loss from the batteries while waiting to be used, and energy loss when the batteries are discharged to power the car. Also, gasoline burns a lot cleaner than coal (especially high-sulfur coal). Of course, you might also want to include the pollution generated when the gasoline is refined, but that is often done even farther away than the electricity generation plants, so will have a minimal effect on local pollution. StuRat (talk) 02:41, 26 February 2008 (UTC)[reply]

I'm not much concerned with the environmental impact. I'm sure it'd be negligible regardless. I'm more looking for cheap maintenance, in which budget I count gasoline. Also, electric cars are one step closer to flying cars. (We can only hope.) I've looked through our articles some, but they don't give a lot of actual advice. I like the list of points, though. Range and top speed had already ruled out those funny golfcart things. I'm looking for something near or under $10,000, which I think tends to rule out hybrids. Are there any safety problems I need to worry about - electrocution, stalling out, that kind of thing? Especially with something reworked from an old gas-powered car. Black Carrot (talk) 04:09, 25 February 2008 (UTC)[reply]

Also, don't forget Electric vehicle conversion, which points out some useful links, such as diyelectriccar.com forums. You might want to post these questions there. Dforest (talk) 10:34, 25 February 2008 (UTC)[reply]

I don't see much hope than some retrofitted frankencar will save you money. Where would you take it for service? Cheap electrics are on the way soon-ish. If you want practical and cheap, look for a plain-old used economy car. As long as you don't want good top speed or acceleration, that is (but honestly, who cars about top speed as long as it's not impractically slow?) Friday (talk) 14:36, 25 February 2008 (UTC)[reply]

There are some rather small electric cars that aren't meant for highway travel, but just as a commuter vehicle in the city (think of the type of vehicles meter-maids sometimes drive). In that case, the top speed doesn't need to be more than, say 45 MPH. Those who do want to drive on the highway will have to ensure that the vehicle can do a comfortable cruise speed for them. In the US there are some 75 MPH speed limits, and many people might drive 80 MPH. A top speed of 90 MPH would cover any emergency passing needs on such a road. StuRat (talk) 02:22, 26 February 2008 (UTC)[reply]

Racecar drivers. See, Tesla Roadster. On a side note, electric cars are far more efficient that ICE cars, or hydrogen cars. Issues of range and acceleration will be improved in the future. 64.236.121.129 (talk) 17:21, 25 February 2008 (UTC)[reply]

Uhh, the guy is looking for cheap basic transportation. If he was looking for high-priced exotic electric sports cars, I imagine he'd have said so. Friday (talk) 18:31, 25 February 2008 (UTC)[reply]

I'm aware of that. I was illustrating a point that electric cars potentially can match the performance of ICE cars. 64.236.121.129 (talk) 20:15, 25 February 2008 (UTC)[reply]

For what it's worth, the article mentions the top speed is limited to 125. While it's a heck of a neat little car, it's not much of a top speed champ. Once they get the transmission problems fixed it'll be quite formidable in acceleration, though. Friday (talk) 20:27, 25 February 2008 (UTC)[reply]

Keyword is "electronically limited". It can go faster without the limiter. Considering its fuel efficiency equivilent is 135 mpg (most ICE cars are lucky to get 30 mpg), and its range 221 miles (ICE cars usually have a range of over 400 miles, so the Tesla isn't bad), it's definitely an impressive car that displays the potential of an electric car. 64.236.121.129 (talk) 16:33, 26 February 2008 (UTC)[reply]

For $10,000, you can just buy a used Prius. I found three used Priuses in my area for about $10,000 advertised on the Kelly Blue Book web site. They’re available now, they don’t require any retrofitting, parts and maintenance are readily available, their fuel cost is considerably less than with most cars, and you can quickly fuel up anywhere. MrRedact (talk) 21:39, 25 February 2008 (UTC)[reply]

I'd be a bit worried that the batteries might be near the end of their life, though. Once they die, you might do best to total the car rather than pay to replace them. StuRat (talk) 02:22, 26 February 2008 (UTC)[reply]

Of the three used Priuses currently being advertised via Kelly Blue Book in my area for $10K, one has 66,350 miles on it, one has 95,584 miles on it, and one has 103,800 miles on it. Toyota says that the battery is designed to last about 180,000 miles.[18] If the battery does need replacing (and it's not supposed to), it will cost about $3,000 to replace it, which isn't cheap. But even if that does happen, I think a total of $13,000 for a used Prius with a brand new battery and lots of usable milage left on the car is still a not unreasonable price for it. MrRedact (talk) 05:04, 26 February 2008 (UTC)[reply]

Sounds good, but two thoughts: Is mileage the only thing that matters for battery life, or do age and other factors matter, too ? Also, is 180,000 miles when the batteries quit completely ? If so, they may only hold a greatly reduced charge for a long time before they finally die. StuRat (talk) 06:04, 27 February 2008 (UTC)[reply]

Why did the use of Greek fire stop?

Following on from "boiling oil" above, and Gwinva's ref to Greek fire, why did it fade away and how was the formula kept secret? (or should this go to the humanities desk?)Julia Rossi (talk) 01:43, 25 February 2008 (UTC)[reply]

I imagine it was a less effective weapon than cannons, which can be used at a far greater range. StuRat (talk) 03:08, 25 February 2008 (UTC)[reply]

Cannons? Cannons have a completely different role as artillery. It's not comparable at all. I asked this question on the humanities page, and the consensus was that the technology to use it had been lost. 64.236.121.129 (talk) 17:02, 25 February 2008 (UTC)[reply]

If your opponent had cannons and you were to rely on Greek fire, you'd never get close enough to use it, as their cannons would sink you first. If your weapons have a shorter range than the enemy, you're at a severe disadvantage. There may have been other technologies between the two, as well. StuRat (talk) 02:12, 26 February 2008 (UTC)[reply]

What's stopping you from using both? Your argument is in line with saying that tanks are useless since attack helicopters can destroy them. They serve a purpose, that's why they are used. Greekfire logically served a useful purpose which was not in the artillery role. 64.236.121.129 (talk) 16:24, 26 February 2008 (UTC)[reply]

Tank columns are relatively useless against an enemy which has enough attack helicopters to render them ineffective (like when the Iraqis tried to use tank columns against the US in 2003). However, since many enemies don't have enough attack helicopters, tanks can still be effective against them. The difference with ships equiped with cannons is that there is never any question of whether there are enough ships equiped with cannons to render the Greek fire ineffective, as a single ship with cannons (the target of the Greek fire) would be entirely capable of sinking the attacking ship using cannons long before it came into range to use the Greek fire. The older technique of ramming ships in order to sink them is also no longer used for many of the same reasons that Greek fire can't be used (it requires getting closer than modern warfare allows and could damage the attacker almost as much as the target). Now, if Greek fire could be kept on the ship with no negatives, like the risk of it exploding when struck, and didn't take up valuable resources like space and crew to operate, then it might make sense to have a "backup plan" in case enemy ships did get into range. However, decreasing the number of cannons to make room for Greek fire would be a rather poor decision that would lose you more battles than it would win. StuRat (talk) 05:38, 27 February 2008 (UTC)[reply]

Darn good question. Since we don't even know what the stuff was, it's hard to even speculate. My own supposition is that it was probably almost as dangerous to those using it as to those it was being hurled against. If it spilled, or if the "syringe" it was shot with burst, you'd be in big trouble!

As to the secrecy of the formula, I'm not sure, either, but if Coca-Cola and Kentucky Fried Chicken can manage it even in far-flung multinational corporations with millions of employees, presumably some clever Greeks could figure out a way, too. —Steve Summit (talk) 03:57, 25 February 2008 (UTC)[reply]

I think these "secrets" are more or less myths spread by the marketing division - I think every good food scientist could come up with some stuff with taste and flavor sufficiently similar to Coca-Cola so that nobody will note the difference (and not every Coca-Cola tastes the same to begin with; see also OpenCola). Icek (talk) 14:49, 25 February 2008 (UTC)[reply]

Hmm, their secrets aren't even mentioned in the articles – which dovetails nicely with "boiling oil" : ) Julia Rossi (talk) 04:24, 25 February 2008 (UTC)[reply]

Knowledge doesn't have to deliberately kept secret for it to be lost, of course. Few people these days know much about (for example) thatching or hedge laying, yet that would have been common knowledge in days gone by. People find new ways of doing things, and the old are lost. You can imagine the scenario: "Let me teach you how to make Greek Fire, my boy." "Grandfather! Don't be so silly! No one uses that anymore. It's old fashioned and dangerous, and utterly pointless. But let me show you what I learnt at school today..." New technologies were better (or were perceived to be better). Certainly, as Steve says above, it must have been pretty dangerous to work with. Gwinva (talk) 04:40, 25 February 2008 (UTC)[reply]

Hi Gwinva – I rather had in mind that at the time it was being used, others didn't seem to have the weapon (just going on the article) because the formula was a secret. Like your generation example, though, the Khitan Queen Shu Li seemed to trust in cavalry technology[19] so flamethrowing didn't catch on for some time and when it did, followed the gunpowder fuse solution. Julia Rossi (talk) 05:41, 25 February 2008 (UTC)[reply]

Well, and we've discussed a few times on here in the past that flamethrowing is difficult to do well in anything but a purely defensive or naval role. The range is very much a factor of the size of the apparatus before you have things like propane. There's a kind of naive belief floating around that flamethrowing is some sort of super technology, but compared with something like, say, the crossbow, it is not really all that effective (and far more dangerous to handle) and too hard to mobilize en masse. --98.217.18.109 (talk) 15:10, 25 February 2008 (UTC)[reply]

No one said they are a super technology, nor have I heard anyone ever say they were. They can be superior weapons to crossbows, depending on what flamethrower you are using. Flamethrowers were used during WW2 while crossbows were not, and for good reason. 64.236.121.129 (talk) 17:02, 25 February 2008 (UTC)[reply]

Crossbows most certainly were used in WWII. Its a neat commando weapon, silent, but better range than a knife.SpinningSpark 18:19, 25 February 2008 (UTC)[reply]

Source? 64.236.121.129 (talk) 20:13, 25 February 2008 (UTC)[reply]

Bah. Such a comment is unnecessarily inflammatory, particularly in light of all the other claims made in this section. Can we just note that crossbows-to-flamethrowers is apples-to-oranges anyway and move on? — Lomn 20:16, 25 February 2008 (UTC)[reply]

There's nothing inflammatory about requesting a source to a claim made by someone. If you make a claim, burden of proof is on you. 64.236.121.129 (talk) 16:24, 26 February 2008 (UTC)[reply]

I felt the manner, if not the substance, of the request was inflammatory (and granted this can be quite subjective). "Source?" reads quite brusquely to me, and a brusque request coupled with your own lack of sourced claims above led to my conclusion. If you really want a source, though, the first Google hit for "ww2 commando crossbow" is all you need -- surprisingly simple to find. — Lomn 20:26, 26 February 2008 (UTC)[reply]

Um, my comment was specifically and carefully written to indicate that I was talking about pre-modern flame throwers. It's obviously a different game when you're talking about ones of a modern design. As for a "super technology," I've seen flame thrower/Greek fire questions again and again on here with people wondering why they weren't being used constantly. That's all I'm referring to. They weren't used constantly because technologically speaking they had severe limitations (and still do, to some degree, which is why they aren't being used constantly in warfare these days either). --98.217.18.109 (talk) 22:46, 25 February 2008 (UTC)[reply]

Not quite. You didn't specify what you were referring to exactly. In any case, like I said before, the non-use of greek fire has been attributed mostly to the loss of the technology to create it, rather than the percieved lack of usefullness of it. 64.236.121.129 (talk) 16:24, 26 February 2008 (UTC)[reply]

But similar things have been invented and re-invented many times over the course of history. If there was a technical need for it, it certainly could have been re-invented again, it was not exactly unknown, and though we like to mythologize Greek fire itself, making flammable substances and liquids is something humans have been able to do for quite some time. --98.217.18.109 (talk) 13:51, 27 February 2008 (UTC)[reply]

I wondered what 64.236.121.129 and 98.217.18.109 were referring to with these allegedly frequent references (since I'd never heard of Greek Fire at all, let alone here on the RDs), but they're right, it has come up time and again. If anyone else is curious, try this google search. —Steve Summit (talk) 23:27, 25 February 2008 (UTC)[reply]

It's not super frequent but this is the third time in basically as many months, so it stuck in my mind. --98.217.18.109 (talk) 00:44, 26 February 2008 (UTC)[reply]

earthworms

1.Uses of earthworms to the soil? 2.Importance of earthworms? 3.What nutrients it can give? —Preceding unsigned comment added by 121.1.14.122 (talk) 10:58, 25 February 2008 (UTC)[reply]

Check out the Earthworm article, in particular, Earthworm#Benefits. Dforest (talk) 11:12, 25 February 2008 (UTC)[reply]

The tunnels they make help loosen the soil. Their waste products are also full of nutrients which are good for plants. 64.236.121.129 (talk) 17:18, 25 February 2008 (UTC)[reply]

You might enjoy our Vermicompost article.

Atlant (talk) 13:52, 26 February 2008 (UTC)[reply]

Purchasing Explosives

Hello, this is a totally serious question, although it might seem stupid to some.

I am a theatre technician (UK), who often detonates small pyrotechnics on stage, often Lemaitre pyro pods. However, I am becomming increasingly interested in the area and science behind theatrical explosions, and would like to detonate something slightly bigger (not onstage obviously).

How are the big explosions achieved in films, and how can I buy these explosives? I know they don't just ignite a barrel of fuel, there's cables and firing devices and timecode involved. But how do they actually purchase the explosive material to start with? A google search provides me with no information.

I'm 22, but naturally no way to prove it, please do not answer if you fear I'm a terrorist etc :) Radiofred (talk) 11:44, 25 February 2008 (UTC)[reply]

A lot of it is just petrol (or gas in USA), they first aerosolise it with a small explosive and then light it, thus producing a large fireball without an explosion. It is therefore safer to use 'near' people than high explosives.--Shniken1 (talk) 12:07, 25 February 2008 (UTC)[reply]

Vanishingly minor quibble: "gasoline" is more usual where you have "gas". I don't understand it myself. Our cars do run on "gas", not so much "gasoline", but an arsonist will have used "gasoline" as an accelerant and not "gas". Just a tip for the Brits and the rest. --Milkbreath (talk) 15:07, 25 February 2008 (UTC)[reply]

Thankyou, I never knew that. But I did know the word was modelled after Vaseline. So if you use that product on your hair would one be said to have Vassed ones head, but if a nefarious villain then sets it alight would he be said to have vaselined the victim? SpinningSpark 15:36, 25 February 2008 (UTC)[reply]

I don't think so; the weirdness seems to be only for the one word. My gut understanding (as a native speaker of American), which of course I've never needed to verbalize previously, is that "gasoline" is a substance whereas "gas" is a (literal, conceptual, or metaphorical) fuel — never mind that they often chemically coincide. A sports team that stops playing well toward the end of a game might be said to be "running out of gas", but it would make no sense at all to say that they were "running out of gasoline" unless the fluid were actually somehow part of their strategy. You would certainly be understood if you said you were putting gasoline into a vehicle (though it would probably be interpreted as noting that the vehicle did not use diesel fuel), but you would never say that to accelerate you needed to "give it [the engine] some gasoline", despite the fact that you are literally doing so. --Tardis (talk) 17:00, 25 February 2008 (UTC)[reply]

Since when was 'American' a language............you speak English! —Preceding unsigned comment added by 84.67.199.152 (talk) 20:56, 26 February 2008 (UTC)[reply]

I took it as tongue-in-cheek. I think the gas/gasoline thing is mainly an issue of context. When we refer to "putting gas in the car" it is clear we are talking about gasoline; in other contexts, it might not be so clear. Dforest (talk) 10:30, 27 February 2008 (UTC)[reply]

You know you need a licence for what you are doing - right? See here [20] if you are storing stuff in London, or if not you should contact your local authority.

Didn't have any trouble getting hits on Google myself - try this search string [21] SpinningSpark 13:23, 25 February 2008 (UTC)[reply]

Oh, and they will probably want to see some kind of qualification (NVQ or such like) before they allow you to have any of the big-boys stuff. Can't give you any real guidance with that though. SpinningSpark 13:35, 25 February 2008 (UTC)[reply]

My impression on the gas/gasoline dichotomy is that it comes from "gas"'s extreme similarity to the word "gas", which is obviously unrelated. In cars, at least unless people are dumb enough to go for hydrogen power, there's no confusion and we can afford to use the abbreviated form exclusively, even to the point of building idioms around it as Tardis pointed out. In this application, though, there's the real possibility that someone might be igniting a gas, so it's important to keep the distinction. Black Carrot (talk) 20:11, 25 February 2008 (UTC)[reply]

• The police link and the google search are both appreciated!! Thanks! In all honesty I'm far too poor to purchase any now, but am very interested in researching the field. Thanks. Radiofred (talk) 00:14, 26 February 2008 (UTC)[reply]

There is a likelihood that when someone experiments with explosives and starts scaling up cute little explosions, the result will be death, blindness, severe burns, or loss of fingers. Edison (talk) 05:26, 26 February 2008 (UTC)[reply]

• Luckily, I know the difference between 'experiments' and 'responsible, controlled research'. Even small stage pyros have taught me the proper procedure with handling, storage, arming and firing. But thanks for your concern, especially for other less sensible people reading this. Radiofred (talk) 12:17, 26 February 2008 (UTC)[reply]

- I reiterate, speaking from experience: if a chem book or other source says (actual chemicals redacted) "Soak a crystal of ----- in ----, let it dry, and the resulting -------- will be set off by the slightest contact or even a puff of wind", do not succumb to the temptation to make a larger amount at one time. Edison (talk) 22:51, 26 February 2008 (UTC)[reply]

• I have no interest in making them, I wish to purchase explosives and use electrical firing systems. I'm not a chemist, I'm not gonna kill myelf in my kitchen trying to make my own explosives. Radiofred (talk) 10:54, 27 February 2008 (UTC)[reply]

color

The pattern on a piece of cloth consist of red triangle on a blue background what colors would appear onthe cloth in red and in green light —Preceding unsigned comment added by 205.217.233.30 (talk) 20:12, 25 February 2008 (UTC)[reply]

Under red light, the cloth would appear as a red triangle on a black background. Under green light, the cloth would appear solid black. MrRedact (talk) 21:45, 25 February 2008 (UTC)[reply]

Think about this, because the point of this question was to make you think, not just to give the right answer. What does it mean when something is red? Does the red triangle absorb red light, or reflect it? What does it do to other coloured light? What about the blue background, why is it blue? Does it absorb or reflect red light? If you don't understand how to work this out, ask because you will need to be able to do this yourself in future. 130.88.140.122 (talk) 09:57, 26 February 2008 (UTC)[reply]

The answer to the question depends on how saturated (narrowband, monochromatic) the light sources are and how narrowband is the color filtering of the cloth swatches.

Atlant (talk) 13:51, 26 February 2008 (UTC)[reply]

Yeah, I figured someone would come along with a more precise answer. Under red light, the background would likely appear as more of a dark red rather than pure, pitch black. And both colors would likely appear as more of a dark green under a green light, rather than pitch black. How close those colors come to pure black would depend on properties of both the light source and the fabric pigment, as Atlant points out.

Furthermore, under green light, the two reflected colors may well differ in how close to black they appear, such that it’d be possible to visually distinguish between the triangle and the background. The triangle is likely to appear lighter than the background in this case (because the responsivity spectra of M human cone cells overlaps with that of L cells more than that of S cells), but again, it’s impossible to say that for sure without knowing more precisely what you mean by “red”, “green”, and “blue” in your question. Two kinds of red light, for example, that appear identical when reflected off of a white piece of paper, can appear quite different when reflected off of different colored surfaces. Similarly, two shades of red paint that appear identical under sunlight can appear quite different when illuminated with a different light source.

The original answer I gave would be exactly correct according to 3D modeling software like OpenGL or Direct3D, in which “pure red”, “pure green,” and “pure blue” have an unambiguous meaning for both light sources and surfaces. But the real world is a little more complicated than the approximate reality modeled by the software. MrRedact (talk) 15:45, 26 February 2008 (UTC)[reply]

Role of Urea in concentrating uring

The wiki article on the Thick Ascending Limb of the nephron says something that seems contradictory to me.

1: The medullary thick ascending limb remains impermeable to water. 2:Urea which remains in the loop creates a solute potential that prevents water completely osmosing out into the interstitial space. This means that while almost all the ions are reabsorbed, there will still be some water in the urine, and hence, the concentration of the filtrate in the loop is decreased here. (If only ions were present, and a certain amount of ions were reabsorbed, one would expect the same amount of the water to be reabsorbed too, and hence the concentration would remain the same, but this is not true.)

How can 2 be true if the TAL is impermeable to water? What is the role of Urea here?

Many thanks Horia (talk) 20:17, 25 February 2008 (UTC)[reply]

Its role in concentrating urine can be found in these articles: Urea and countercurrent exchange. Wisdom89 _{(_T / ^C)} 00:07, 26 February 2008 (UTC)[reply]

that doesn't solve the contradiction between 1 and what's in italics in 2. I'll just assume it's wrong and probably change it soon.Horia (talk) 22:51, 26 February 2008 (UTC)[reply]

February 26

the ocean

What is a volcano called in the ocean? What are the low hills and plains in the ocean called? What causes waves to form?

--Shayshay789 (talk) 00:46, 26 February 2008 (UTC)shayshay789[reply]

Volcanoes in the ocean (as far as I have been told) are called volcanoes. Waves can form due to wind or seismic activity. (Waves formed by the latter are usually huge and are referred to as tsunamis.) This is as much as I know about this particular subject. Someone else, therefore, will probably be able to provide you with a more complete and detailed (perhaps corrected?) response. Hope this is of help, Zrs 12 (talk) 02:10, 26 February 2008 (UTC)[reply]

Wikipedia has some good articles about these, which would be a good place to start. Try Submarine volcano, and the very detailed Ocean surface wave and Tide articles. Gwinva (talk) 03:13, 26 February 2008 (UTC)[reply]

Abyssal plain is the name for the deep flat plains on the ocean floor. The flat bits that are shallow near the continents are Continental shelf parts. Hills may be Seamounts and could be cause by volcanoes, tectonic uplift around faults, or erosion. Graeme Bartlett (talk) 10:57, 26 February 2008 (UTC)[reply]

food processoring

I've noticed that my body does not always digest every particle of food I eat. Sometimes when I am in a hurry I've noticed even whole kernels of corn in my poop. To prevent this I've started using a food processor to break everything down into a paste. How much less food will I have to eat if it is pre-macerated in this way or how much and/or how many more nutrients will be absorbed by my gut? 71.100.9.94 (talk) 02:34, 26 February 2008 (UTC)[reply]

provided you chew the food processor shouldn't be neccessary —Preceding unsigned comment added by 83.100.138.74 (talk) 04:51, 26 February 2008 (UTC)[reply]

Many people do not live a slow backward life which allows them to consume a single meal over the course of 5 hours. Besides, anyone can still chew pre-macerated food if for only the purpose of adding enzymes found in saliva. However, that was not the question. The question is not whether it is necessary to pre-macerate food but rather the benefit - just like riding a bicycle is not necessary but to most offers a benefit. 71.100.9.94 (talk) 12:02, 26 February 2008 (UTC)[reply]

Wikipedia does not provide medical advice. If you are seriously concerned about this, please consult a nutritionist. Dforest (talk) 08:37, 26 February 2008 (UTC)[reply]

Why would I ask the Wikipedia for medical advice? Isn't it more logical that I would come to the Wikipedia to find a reference for studies that have been done on eating pre-macerated food? Why man the reference desk if you are too lazy to help find a reference? 71.100.9.94 (talk) 12:02, 26 February 2008 (UTC)[reply]

It's not a function of "laziness"; rather, it's more likely a recognition that we're not qualified to properly evaluate the merit of such studies that might be found. I don't personally think this is really a medical advice issue, but Dforest's point absolutely stands: if this is a matter of real concern, address it with your doctor. — Lomn 14:15, 26 February 2008 (UTC)[reply]

Nosense. He has no point, having wrongfully assumed medical advice was sought, ...and that is being generous. His response was for the purpose of showing you he was capable of upholding a rule that has no other purpose for application here. Even below he continues to relate this question and the answer to medicine while it is completely unrelated to anything except scientific biological studies to which medical researchers might refer but would not likely conduct.

Even if someone asks for medical advice you do not have to make an issue of Wikipedia policy as the answer but rather provide encyclopedic references so they might continue their research themselves. That is your job isn't it? Even in his response below after my telling him the question is not medically related he has cited a medical reference and not references of scientific studies which are not medically based. It is his mind set that is the problem and not how my question was phrased.

Aside from that he did not ask if I was seeking medical advice but made a wrongful assumption and then rudely cut me off. Now you are wrongfully coming to his rescue and defense rather than correcting him for the mistake of 1. making a false assumption and 2. not correcting his assumption and rather providing a reference which was not sought.

Actually, I'm "coming to his defense" because your conduct is lousy. Simply put, catering to your whims and your interpretation of Ref Desk guidelines is not my job nor anyone else's. I noted above that I was sympathetic to the merit of your question, but that does not mean I condone your insults towards respondents. — Lomn 14:17, 27 February 2008 (UTC)[reply]

Since you phrased your question in terms of a concern with your body it seemed as if you were looking for advice to medicate, or to change your diet. Hence the disclaimer. If you are looking for studies, PubMed is a good place to start. Dforest (talk) 22:49, 26 February 2008 (UTC)[reply]

I am not looking for medical studies. Having been so informed you now need to update your wrongfully assumed and false mindset.

I suggested that only chewing should be neccessary because that's how it (the body) works - coverting the food to a fine pulp might help you to extract more, but may not be the best choice for digestion. —Preceding unsigned comment added by 87.102.42.162 (talk) 15:09, 26 February 2008 (UTC)[reply]

Regarding corn – my understanding is that the centre of the kernel is digested, but the bright yellow surrounding passes through essentially untouched. This may well be what you're seeing. Angus Lepper^{(T, C, D)} 18:57, 26 February 2008 (UTC)[reply]

Taigas

what are adaptations to animals in the taigas of the world? What are examples of symbiosis in these taigas? I have checked wiki already in their subject of taiga but there is nothing about symbiosis. —Preceding unsigned comment added by 203.148.171.10 (talk) 04:00, 26 February 2008 (UTC)[reply]

In the fauna section they mention that many of the animals have adapted to survive in a harsh climate. Adaptations such as hibernation and layered fur/feathers as well as the ineffeciency of carnivorous diet. I would suggest looking into some of the animals that are linked in that section if you want to see specific examples. -- MacAddct  1984 ^{(talk  contribs)} 04:21, 26 February 2008 (UTC)[reply]

Plugging both speakers in to one channel of a preamp

Hello, this is a pretty n00bish question so I'm sorry if the answer is painfully obvious. I have a preamp, but the left channel is busted (it's my dad's old Marantz preamp from the 70's - typical big old basement setup). My friend had the exact same situation and he told me to just plug both speakers in to the output of the channel that works, so since each channel has two little output clips and each cable coming from each speaker has two little copper wire ends, that would make two copper wire ends per clip....if that makes sense. I would be panning the sound completely to the right, and have both speakers hooked up to that channel. The preamp has a button that converts the signal to mono so I don't have to worry about losing sound from the left channel. Just wondering if they will be very underpowered? I'm bringing the preamp and both speakers to a party in a basement, and I intend on blasting some party classics pretty loud without damaging any equipment. Thanks a lot! NIRVANA2764 (talk) 04:06, 26 February 2008 (UTC)[reply]

Yep - you only get mono - not stereo - you're big worry is the resistance of the speakers - since the speakers are connected in parallel you are effectively having the resistance eg if your speakers are labelled 8ohms then the resistance combined is 4ohms - most amps have a minimum resistance they can use - check this and compare - if the resistance is too low you risk overheating the amplifier and potentially losing another channel..

ps in the uk 'preamps' are usually not amplified - there are pre/power combinations - I believe that in the us pre-amps are sometimes powered - bit confused about that.

If the resistance is too low connect the speakers in series as another option.

It all depends on the specs of your speakers and of the amp - suggest you supply these.

For safety just connect one speaker - unless the amp is much more powerful than the speakers need you wouldn't get much benefit from paralleling - if the amp is powerful then do it.83.100.138.74 (talk) 04:48, 26 February 2008 (UTC)[reply]

I concur you should do fine selecting mono to make sure the output includes bots stereo channels mixed together, then using only one speaker connected to the output that works. Enjoy! Edison (talk) 05:23, 26 February 2008 (UTC)[reply]

Nah. More speaker area is better. And if you don't want to bother about calculating impedances, you can't hurt anything by wiring the speakers in series: [Amp+...+...Speaker...-+...Speaker...-...Amp-]. A "preamp" does not have speaker outputs in any country; an "amp" or "amplifier" or "receiver" does. --Milkbreath (talk) 11:55, 26 February 2008 (UTC)[reply]

Assuming the output of the amp is 50 watts per channel into 8 ohms for each channel when normally connected to the speaker, and that it is a constant voltage output (that can certainly be debated). Now hook 2 speakers in series: the impedance of the load (speakers) doubles and the total output power from the one channel into the two speakers in series becomes only 25 watts.(Same voltage divided by twice the impedance). "More speaker area" may be wonderful, but with half the output power the volume is going to be quite a bit lower. If the amp somehow produces more like constant current then the voltage would have to increase to keep the volume constant. Edison (talk) 22:46, 26 February 2008 (UTC)[reply]

Unidentified bathroom fly or moth

For several years now, I keep encountering this small insect in public restrooms, and recently, the bathrooms in my home. I see them only in bathrooms and nowhere else. They look like little flies with round bodies. The wingspan when "parked" is about 3mm from tip to tip. They fly silently without a discernible sound although their wings are a blur. They don't fly fast; they seem easily blown about by breezes, which may explain a preference in the relatively still air of a restroom.

I have no idea where they come from, or why I see them only in restrooms. I suspect they may come out of the drains, hatching from larvae attached to spaces in the pipes where they won't get washed away.

I've been seeing these for so many years, and finally got around to taking a photo of one, so I thought I'd ask here. If an article has been written about it, I certainly can't find it.

So, anyone know what insect this is? =Axlq 07:11, 26 February 2008 (UTC)[reply]

I have seen these little chaps but only in our bathroom in southern Spain. Can you provide some geographical location. Richard Avery (talk) 07:54, 26 February 2008 (UTC)[reply]

I am in the United States. I have seen these flies throughout the country (from Washington DC to San Francisco), and I recall seeing them in other countries as well. =Axlq 17:40, 27 February 2008 (UTC)[reply]

It's an adult Bathroom Fly (Drain Fly) Clogmia albipunctata (also: Telmatoscopus albipunctatus), Diptera: Psychodidae. Julia Rossi (talk) 08:22, 26 February 2008 (UTC)[reply]

Link: Bathroom Fly. —Lowellian (reply) 01:08, 27 February 2008 (UTC)[reply]

PS It's a beautiful double angle shot (complete with bathroom environment lighting) you might like to put it in the article. Julia Rossi (talk) 08:32, 26 February 2008 (UTC)[reply]

As I recognise myself in the above depiction of a barfly, I stress that a publication of the image will be met with my strongest objections. I feel it an intrusion of my private pa- oops, my private sphere if a photo of me rubbing my proboscis in the intimate environment of Axlq´s bathroom could be used by sundry psychos and didiae for their lustful debauchery. --Cookatoo.ergo.ZooM (talk) 21:32, 26 February 2008 (UTC)[reply]

Shoo. —Preceding unsigned comment added by Julia Rossi (talk • contribs) 21:59, 26 February 2008 (UTC)[reply]

I'm happy to add it to the Bathroom Fly article. And thanks User:Lowellian for adding a redirect for bathroom fly - my previous search for that term turned up with nothing, which led me to ask about it here. Years of wondering about this little bug have now been answered! Thanks! =Axlq 17:40, 27 February 2008 (UTC)[reply]

"Shut-in" oil production

What is 'shut-in'oil prodution? "The Nation's economy lost $45.49 Billion...in the last three years...to shut-in crude oil production in the troubled Niger Delta. The shut-in was occasioned by the activities of militants...(Nigerian newspaper Vanguard). Thanks if you can explain. —Preceding unsigned comment added by 83.229.85.138 (talk) 10:32, 26 February 2008 (UTC)[reply]

From a look around it looks like it means production from wells that have previously been 'shut in' (i.e. had the entrance filled). I guess this much based on the following paragraph in an article "Thus, last week's seemingly hefty price was just 20 cents a barrel more than last January, and until the future is clearer, L.A. oilmen are not rushing out to uncap and resume production from shut-in wells. West Coast crude oil stocks remained above the lofty 80-million-barrels mark, according to American Petroleum Institute figures: a towering 86.6 million barrels as of Aug. 10.5 percent above the 78.34 million of a year earlier." (http://findarticles.com/p/articles/mi_m5072/is_n33_v13/ai_9395087). ny156uk (talk) 18:34, 26 February 2008 (UTC)[reply]

A shut-in well is temporarily "closed" or blocked from production. It can be re-opened. In contrast, a well that is plugged and abandoned cannot be re-opened without considerable difficulty. Cheers Geologyguy (talk) 03:39, 27 February 2008 (UTC)[reply]

knee surgery

what is involved in a full knee reconstruction? —Preceding unsigned comment added by 81.139.65.131 (talk) 10:35, 26 February 2008 (UTC)[reply]

Take a look at knee reconstruction, but we cannot give medical advice. Graeme Bartlett (talk) 10:59, 26 February 2008 (UTC)[reply]

Does hand sanitizer kill viruses?

The cold virus for example. Also, does alcohol kill viruses? 64.236.121.129 (talk) 18:12, 26 February 2008 (UTC)[reply]

See alcohol rub: "Alcohol rubs kill many different kinds of bacteria, including antibiotic resistant bacteria and TB bacteria. Alcohol rubs inactivate many different kinds of viruses, including the flu virus and the common cold virus. Alcohol rubs also kill fungus." -- MacAddct  1984 ^{(talk  contribs)} 19:21, 26 February 2008 (UTC)[reply]

It also depends on whether or not the virus posseses a lipid envelope. Viruses that do are more susceptible to antiseptics such as ethanol and acetone as they permeabilize the lipid. Wisdom89 _{(_T / ^C)} 19:24, 26 February 2008 (UTC)[reply]

Can hand sanitizers breed resistant mutants like antibiotics do?128.163.174.150 (talk) 23:57, 26 February 2008 (UTC)[reply]

In my opinion, it's possible in the sense that anything with evolution is possible if you give it enough time. But I don't believe there are any cases of this occuring. 64.236.121.129 (talk) 14:28, 27 February 2008 (UTC)[reply]

SRS statistics

Which direction of sex reassignment surgery is more common - male to female or female to male? (The answer is probably obvious, but I'd still like to be sure.) - Sikon (talk) 18:13, 26 February 2008 (UTC)[reply]

We have a section on this: Transsexualism#Prevalence. (EhJJ)^TALK 23:12, 26 February 2008 (UTC)[reply]

Harmonics (?) with RF emissions causing lights to go out

Recently I saw a demonstration of a radio transmitting on HF causing flourescent light tubes to dim and, at one frequency, turn off altogether. I am not sure if a similar effect was seen on mains powered devices. I am attempting to reproduce this behaviour... does anyone have any tips as to what the correct frequency might be or how much power output I would need? Thanks, Martinp23 19:31, 26 February 2008 (UTC)[reply]

I discovered today that a freq. of 5 Mhz (and many others presumably) with output of 30W would cause a light tube held to the antenna to light up. Any ideas as to my original question? Martinp23 17:52, 27 February 2008 (UTC)[reply]

Engineering(Naval Arts) - detrimental effects on ship cause by twisting propulsion engines

Example :

A ship have 2 propulsion engines on individual throttle(which means you could control each engine by it's own throttle) are at different speed and direction. One of the engine is at half ahead(half forward thrust), while another is on full astern(full backward thrust). This action is called twisting.

Information :

1.) There are a lots of stresses on the ship's hull. 2.) Vibration

My questions :

1.) What are the bad effects on the ship? 2.) The damages that this action(twisting of engines) could caused?

Thanks Boonyuan (talk) 19:52, 26 February 2008 (UTC)—Preceding unsigned comment added by Boonyuan (talk • contribs) 19:49, 26 February 2008 (UTC)[reply]

It seems that you've basically answered your own question -- the negative effect on the ship is an increase in hull stress. The potential damages are those caused by such stress -- failure (to varying degrees) of the hull. Hopefully, though, anybody who's designed a ship to allow one prop at full forward and one at full astern has designed the hull to accomodate such a scenario. I imagine this would be used to tighten a turn radius, though I expect the drag caused by the rest of the hull is quite impressive. — Lomn 20:22, 26 February 2008 (UTC)[reply]

Killing the Bass

I, like many, are annoyed by certain people pumping up the bass in their cars to tremendous levels (sometimes at 4 in the morning) and have wondered about how to stop it. I imagined that there must be a way to make their bass speakers stop functioning using some sort of inverse sound wave or such. Naturally, I know practically nothing of such things - my mind just makes up pseudoscience at random. But I wonder if it would be possible in any way to kill someone's bass speakers using a device no larger than, say, a toaster. Don't misunderstand me, I have no intention of building such a thing, since that would bring me down to their level of rudeness. Is there any way to do what I propose without using EMP, entering the car, or anything of the firearm persuasion? (Edit: Scratch the no EMP part - how about EMP that only affects the specific type of speaker?) 206.252.74.48 (talk) 20:27, 26 February 2008 (UTC)[reply]

Oh, I very much want one of these. Here's one idea for such a system. In terms of scale, you've got to be able to generate enough of a sound wave to break somebody else's big speaker, which means you probably need a big speaker of your own -- so I expect a toaster is out. It also helps if you think of it as raising them to your level of politeness rather than vice versa :) — Lomn 20:43, 26 February 2008 (UTC)[reply]

Well, I already tune my radio transmitter (the kind that plugs into the cigarette lighter) to B96 (the local hip hop station) and blast Tchaikovsky through it. If they are listening to the station my little transmitter is picked up instead. The looks on their faces - absolutely priceless. It doesn't work that often because they use CDs, though. As for my theoretical device, I know the size constrant is a little small, but I originally imagined something I could fit in my pocket. 206.252.74.48 (talk) 21:02, 26 February 2008 (UTC)[reply]

You might also be interested in the active noise control article, the technology behind noise-cancelling headphones -- MacAddct  1984 ^{(talk  contribs)} 21:31, 26 February 2008 (UTC)[reply]

I have witnessed someone silence undesirable radios (not me - honest) by transmitting the IF frequency. The advantage of this technique is that you don't need to know what station the radio is tuned to as the IF is always the same. Again, not effective against CDs though. It might just be possible, though, that a transmitter tuned to some bit-rate used in CD players might be effective for similar reasons. SpinningSpark 00:55, 27 February 2008 (UTC)[reply]

You live in the US? Can't you just call up your local noise control officers to deal with the person making the noise? Nil Einne (talk) 08:41, 27 February 2008 (UTC)[reply]

I expected the USA solution to involve a gun. Shooting out the speaker should lower the volume significantly and deafen yourself enough so that you cannot hear! Earplugs are a lowercost solution to stopping the sound. Graeme Bartlett (talk) 10:29, 27 February 2008 (UTC)[reply]

This question is about my curiousity about such a system, I haven't heard any people blasting bass for a long time - they hibernate during winter, apparently. 206.252.74.48 (talk) 14:18, 27 February 2008 (UTC)[reply]

Dream More...

hi,

is there any way to increase your dream rate?...eg any foods that make you dream more (does cheese actually work?)....an things you can do?

please keep it reletively simple thanks, --84.67.199.152 (talk) 20:49, 26 February 2008 (UTC)[reply]

There's a section on that in the lucid dreaming wikibook. [22] — Daniel 21:06, 26 February 2008 (UTC)[reply]

There's plenty of anecdotal and other evidence that suggests we all dream every night, but the percentage of dreams we remember in the morning is generally low. So it's not so much about about dreaming more, but remembering more. -- JackofOz (talk) 21:16, 26 February 2008 (UTC)[reply]

Well, I'm not aware of any way to increase your dream rate (and I don't trust those "dream pill" sellers, they look like snake oil to me). However, if someone monitors your sleep stage they could wake you up at the end of the REM stage, where you'd be more likely to recall your dreams. Most of the time you simply don't recall your dreams, and this method would allow you to recall more dreams than you normally would. -- Hi Ev 01:52, 27 February 2008 (UTC)[reply]

I don't know about anybody else, but I reliably have much more vivid dreams if I'm too hot, either because I accidentally left the heat on too high, or used too many blankets for the time of year, or have a cat sleeping on my head. —Steve Summit (talk) 01:59, 27 February 2008 (UTC)[reply]

Maybe sleeping uncomfortably (either physically or psychologically) might help? I've found cheese to work but this could be an anecdotal self-fulfilling expectation. — Æµ§œš¹ _{[aɪm ˈfɻɛ̃ⁿdˡi]} 09:04, 27 February 2008 (UTC)[reply]

Faster Hair

hi,

is there anything you can do to make your hair grow faster........eg foods you can eat?

thanks, --84.67.199.152 (talk) 21:43, 26 February 2008 (UTC)[reply]

Nope, it grows at pretty much the same rate (about a half inch per month), no matter what you do.[23] MrRedact (talk) 22:21, 26 February 2008 (UTC)[reply]

If you sleep most of the time, it seems to grow a lot faster. Think Rip van Winkle —Preceding unsigned comment added by 79.76.241.79 (talk) 22:49, 26 February 2008 (UTC)[reply]

You could probably make it fall out though, by eating Strontium 90. SpinningSpark 01:00, 27 February 2008 (UTC)[reply]

It may or may not be an option for you, but you can make it grow much thicker by getting pregnant. —Steve Summit (talk) 01:55, 27 February 2008 (UTC)[reply]

A healthy diet and the use of appropriate shampoo and conditioner, however, may contribute to slowing hair loss, which will affect the speed and maximum length your hair grows. Confusing Manifestation(Say hi!) 05:13, 27 February 2008 (UTC)[reply]

Shadow Dexterous Hand

Could a Shadow Dexterous Hand be used to replace a human hand if you lost one in an accident? If so, could you go further and replace a whole arm or leg with an air muscle limb, or even build a complete robot? DTWATKINS (talk) 23:54, 26 February 2008 (UTC)[reply]

The big difficulty to overcome with anything like this is the control connection to the human body (nerve ending or brain). Some progress has been made with these techniques but there is still a long way to go. See for instance Brain-computer interface and Cyberware. SpinningSpark 01:09, 27 February 2008 (UTC)[reply]

Another problem is that it needs both electricity and compressed air to run. So, even if you could overcome the control problems, you'd have to carry around a backpack with batteries, air compressors, and high-pressure air tanks in it. It would be pretty unwieldy, and occasionally noisy when the air compressor is running. -- Hi Ev 01:23, 27 February 2008 (UTC)[reply]

February 27

Alcohol Rub

What is the gelling agent that is used in Alcohol rubs?? (My guess is a carbohydrate of some sort) --Shniken1 (talk) 00:19, 27 February 2008 (UTC)[reply]

From Hand_washing#Medical_hand_washing: "Most are based on isopropyl alcohol or ethanol formulated together with a humectant such as glycerin into a gel, liquid, or foam for ease of use and to decrease the drying effect of the alcohol." AlmostReadytoFly (talk) 14:28, 27 February 2008 (UTC)[reply]

How deep

How deep is the ocean? —Preceding unsigned comment added by 79.76.241.79 (talk) 00:30, 27 February 2008 (UTC)[reply]

It depends. The ocean is obviously near 0 m deep close to the shore, but its deepest point is the Mariana trench at 11 km. --Bowlhover (talk) 00:58, 27 February 2008 (UTC)[reply]

Unidentified ocean animals

What is this thing: http://i29.photobucket.com/albums/c282/rOll3r_cOast3r_lOv3r/lobb.jpg ? I know it's a lobster, but what kind? —Lowellian (reply) 01:23, 27 February 2008 (UTC)[reply]

Kiwa hirsuta. --Milkbreath (talk) 01:51, 27 February 2008 (UTC)[reply]

What is the bizarre-looking animal in the image at http://www.mbari.org/expeditions/hawaii/Leg2/apr11images/apr11_10_10_12_08.jpg, taken in the ocean near Hawaii? I know the image caption says Holothuroidea, sea cucumbers, but not only is that very vague, but the people taking the photograph were actually very doubtful about this identification themselves (if it's a sea cucumber, then why does it look so much like a swimmer as opposed to a crawler?), which is why they put a question mark in front of "Holothuroidea" in the image caption. Can someone either confirm that it is a sea cucumber and give a more specific identification, or confirm that it is not a sea cucumber but something else? —Lowellian (reply) 01:01, 27 February 2008 (UTC)[reply]

I've seen a lot of real holothuroidea on the east and north-west coast of Oz, so to my mind, it ain't a sea cuke an I ain't goin ocean swimmin no mo'. As for that other hairy thing... mother! Julia Rossi (talk) 08:28, 27 February 2008 (UTC)[reply]

How high is the sky?

How high is the sky? —Preceding unsigned comment added by 79.76.241.79 (talk) 01:05, 27 February 2008 (UTC)[reply]

From zero to infinity (not inclusive). — Lomn 01:29, 27 February 2008 (UTC)[reply]

You sounds like Buzz Lightyear --Dweller (talk) 11:03, 27 February 2008 (UTC)[reply]

See atmosphere. Most clouds are in the atmosphere, a few kilometres up; artificial satellites usually orbit a few hundred to 40 000 km above the ground; the solar system's other planets are hundreds of millions of kilometres away; we'll talk about the distance to stars in the next question. --Bowlhover (talk) 01:41, 27 February 2008 (UTC)[reply]

How far to a star?

How far is the journey from here to a star? —Preceding unsigned comment added by 79.76.241.79 (talk) 01:25, 27 February 2008 (UTC)[reply]

The nearest star (the sun) is 8 light-minutes away, about 150 million kilometers. The nearest extra-solar star (Proxima Centauri) is 4.22 light years away, 275,000 times further. — Lomn 01:32, 27 February 2008 (UTC)[reply]

Ah then you know how much I love you! —Preceding unsigned comment added by 79.76.241.79 (talk) 01:34, 27 February 2008 (UTC)[reply]

You love me 1.3 parsecs? Is that a lot? — Lomn 14:10, 27 February 2008 (UTC)[reply]

I wish Valentine's day hadn't just passed. I know some people who would swoon over that. 199.67.16.60 (talk) 14:54, 27 February 2008 (UTC)[reply]

How to clean up acid/base spills.

Let's say that I spill a strong acid/base, what is the safest way to clean it up? Could someone answer really fast? Thank you. 99.226.26.154 (talk) 01:38, 27 February 2008 (UTC)[reply]

Which is it, an acid or base? How concentrated is it? What is it spilt on?--Shniken1 (talk) 01:43, 27 February 2008 (UTC)[reply]

Let's say Car Battery acid...On...Well...Concrete, or whatever they use to pave the floor of garages. 99.226.26.154 (talk) 01:46, 27 February 2008 (UTC)[reply]

If you spill an acid, neutralize it with copious amounts of a weak base -- baking soda is the canonical example. Contrariwise, if you spill a base, neutralize it with vinegar or another weak acid.

If you work with acids and bases frequently, it's strongly recommended that you keep baking soda and vinegar on hand, so you won't have to go scrambling around looking for some when you have a spill. —Steve Summit (talk) 01:49, 27 February 2008 (UTC)[reply]

(ec) Sodium bicarbonate or sodium carbonate are the common materials used to neutralize acid spills, these are found in commercially available "spill kits". Boric acid or citric acid is typically used for neutralizing alkali spills. However, check the Material Safety Data Sheet first and, if there is large amounts and/or you are notable to determine the effects of those compounds on your particular spill, contact the fire brigade or the appropriate safety personnel. Rockpocket 01:50, 27 February 2008 (UTC)[reply]

Is it good to dilute it with water? Does that work well? —Preceding unsigned comment added by 99.226.26.154 (talk) 01:52, 27 February 2008 (UTC)[reply]

No. According to the MSDS for battery acid "EPA and Superfund reportable discharge is 1000 lbs. Stop flow if possible. Use appropriate protective equipment during clean up. Soak up small spills with dry sand, clay or diatomaceous earth. Dike large spills, and cautiously dilute and neutralize with lime or soda ash, and transfer to waste water treatment system. Prevent liquid from entering sewers, waterways or low areas. Comply with Federal, State and local regulations. Do not dilute it with water. Rockpocket 01:54, 27 February 2008 (UTC)[reply]

Note that battery acid (if it came out of a battery, as opposed to a refill bottle) contains large amounts of lead sulfate, and is therefore highly toxic even after the acidity has been neutralized. --169.230.94.28 (talk) 02:00, 27 February 2008 (UTC)[reply]

Hm...Just curious, but if it gets on skin, can you wash it off with water? Just in case this happens next time. 99.226.26.154 (talk) 02:02, 27 February 2008 (UTC)[reply]

I would say wear (acid resistant) gloves so it doesn't happen. But yes you can wash it off with water. And just to clarify how to clean up said spill. Use lots baking soda to mop up the liquid and neutralise the acid. Then collect the powder and dispose of it through a chemical waste company..--Shniken1 (talk) 02:06, 27 February 2008 (UTC)[reply]

Would about one bottle do for a puddle about the size of a sink? Or do I have to get some more? —Preceding unsigned comment added by 99.226.26.154 (talk) 02:08, 27 February 2008 (UTC)[reply]

What exactly may you clarify happened "This Time"? --99.237.101.48 (talk) 02:10, 27 February 2008 (UTC)[reply]

Nothing...Nothing at all... 99.226.26.154 (talk) 02:18, 27 February 2008 (UTC)[reply]

Thank you for your help! I could not have done this without you. 99.226.26.154 (talk) 02:30, 27 February 2008 (UTC)[reply]

Sorry but isn't it pretty clear that what happened "this time" is that 99.226 spilled some car battery acid on the concrete floor of their garage? (and by the way, I think the singular they is grammatically fine) 81.96.160.6 (talk) 16:24, 27 February 2008 (UTC)[reply]

My invention

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

A question asking about how to go about protecting your intellectual property rights for your inventions is a rather clear-cut case of asking for legal advice. Rather than asking us, please consult with a patent attorney. MrRedact (talk) 05:42, 27 February 2008 (UTC)[reply]

well Mr.redact respectfully, why is it that someone who doese not even know of what proper channels to go through cant ask for a little guidance? as you saw people just pointed to me where i should go.

Respectfully Inutasha De Fallen —Preceding unsigned comment added by Inutasha De Fallen (talk • contribs) 06:18, 27 February 2008 (UTC)[reply]

Welcome to the refdesk Inutasha De Fallen. You might find these helpful links in the pedia such as Inventor (patent), Patent, List of patent legal concepts, patent application, patent pending, First to file and first to invent, United States Statutory Invention Registration, and more here[24]. Then in the refdesk archives you can pick from among these answers[25]. BTW I read the guidelines as guidance and "may be" rather than sure-fire will be removed, so please MrRedact, let's just open up what's in wiki so a person can get themselves orientated before they pay for specific legal advice. Cheers Julia Rossi (talk) 09:21, 27 February 2008 (UTC)[reply]

If you are a first-time inventor you should probably get a patent lawyer. They will look at your claims and give you an honest assessment of how good they think they are. They can also do a search of the prior art and see if your invention is really novel or not. They cost money, but if your inventions are legit it is probably worth it. It's not impossible for someone who is not a patent lawyer to do these things, but if you don't know what you are doing you will probably screw something up and not get the patent. --98.217.18.109 (talk) 13:42, 27 February 2008 (UTC)[reply]

Before paying for a patent attorney, you can research whether your invention is novel by searching through old patents yourself. For example, US patents can be searched for free here, and there is much useful information at the patent and trademark office's web site. --mglg_(talk) 16:47, 27 February 2008 (UTC)[reply]

It's actually a lot easier to search patents using Google Patents (much better than the USPTO website, in terms of searchability, usability, and even total scope), but I just want to note that unless you know what you are looking for it can be very hard to just search patents and expect to make sense of whether or not your invention has been patented before or whether or not you might still have a patentable claim. Patents are, as the name suggests, supposed to be easy for anybody to see and understand, but in reality there is a very specific way of writing and reading them required. It's not impossible to learn how to do this, obviously, but it takes some training and practice. A patent attorney would be able to do this much more reliably than one would be able to one's self, assuming one is not at all trained in such things. You can get some indication of this by just looking at the few "recognizable" patents that Google Patents always has on its front page—something as apparently simple as a Christmas tree stand is actually quite complicated when it comes down to the specific patent claims. --98.217.18.109 (talk) 17:23, 27 February 2008 (UTC)[reply]

Who discovered or invented rock candy?

I searched the internet and I keep running into dead ends, or the same information on alot of sites, but nothing to what I was looking for. I was hoping you could give me the history information on rock candy. Who discovered or invented rock candy? —Preceding unsigned comment added by Gblueproductions (talk • contribs) 05:49, 27 February 2008 (UTC)[reply]

Haven't found who first made hard candy but found roughly when and where as in India and Persia, noted by 9th century Arab writers. Thanks for pointing to an article that needs more help. Julia Rossi (talk) 08:54, 27 February 2008 (UTC)[reply]

Role of sweat and body odor in Human attraction

I was reading an article in the sci section of the NY times that showcased a new idea that encouraged potential partners to smell each others odors as a test for compatibility even before they met in person. This made me wonder, is natural body odor attractive? And if so, are purfumes counterproductive? If pheromones and odor are natural ways to attract the other sex, why is are odor masking techniques so prevalent today? —Preceding unsigned comment added by 76.25.201.104 (talk) 06:20, 27 February 2008 (UTC)[reply]

here's a link to the article i read by the way:

http://www.nytimes.com/2008/02/26/science/26elas.html?ref=science —Preceding unsigned comment added by 76.25.201.104 (talk) 06:24, 27 February 2008 (UTC)[reply]

Reasons people most likely use perfumes to cover these natural odors are because they are very self concious and dont like the way they smell, or they like how the perfume smells so they are trying to make themselves happy. Also most people proably dont know that little tidbit your asking —Preceding unsigned comment added by Inutasha De Fallen (talk • contribs) 06:27, 27 February 2008 (UTC)[reply]

Human sweat can be attractive, because we associate the smell of body odor with something we find attractive (bodies). Whether sweat is innately or inherently attractive is a question of scientific debate. This would make them a pheromone, which is something that has been widely demonstrated to be important in sexual behavior in many animals, but not in humans. Thus, despite what people who wish to sell you sex pheromones might say, there is no proof that humans react to human odors in an innate manner. Rockpocket 06:47, 27 February 2008 (UTC)[reply]

Question about that Rocket cant people start attraction from scent which leads to sexual attraction? —Preceding unsigned comment added by Inutasha De Fallen (talk • contribs) 06:50, 27 February 2008 (UTC)[reply]

There might be a difference in appeal between fresh sweat, stale sweat and sweat that leaves clothes standing up by themselves. Apocrine glands secrete more than moisture and salt which might knock off the initial signal FWIW. Whatever happened to that pheromone perfume people were touting awhile back? OR but here goes: peer pressure can result in using body sprays even if beforehand a person felt quite comfortable not to. I like the bit about feeling happy with perfume. Yeh. Julia Rossi (talk) 08:43, 27 February 2008 (UTC)[reply]

I can only comment on your first question, "This made me wonder, is natural body odor attractive?"

It has been known for a long time, that mice prefer mates which have different Major histocompatibility complex (MHC) genes than their own, and that they can tell whether a mate is similar or different from themselves from the smell of their urine. If pregnant with a mate that is MHC-identical to herself, a female mouse may abort sponaneously if an MHC-different male becomes available. MHC molecules play an important role in the immune system, and it is advantageous to be heterozygous. This is assumed to be the primary reason for this phenomenon. In addition, the mechanism protects against inbreeding. To answer your question directly, go to pubmed, and type

MCH sweat

in the search box. You will get a lot of hits, one of the first is this paper: Santos PS, Schinemann JA, Gabardo J, Bicalho Mda G. New evidence that the MHC influences odor perception in humans: a study with 58 Southern Brazilian students. Horm Behav. 2005 Apr;47(4):384-8. When you click on it, you can read the abstract of the paper. To the right of the abstract itself, you will find a box labelled "Related Links". There you will find related papers. This "Related links" tool in pubmed is excellent, the links tend to be highly relevant. To learn more about this, I suggest you do a similar search using the key words

MCH urine

Happy reading, it's a fascinating story. --NorwegianBlue^talk 10:54, 27 February 2008 (UTC)[reply]

Note that mammals detect pheromones with a specialized organ, the vomeronasal organ, and that in humans this organ regresses during fetal development and is either vestigial or entirely absent in adults. It is therefore unlikely that pheromones play a major role in human sexual attraction. --mglg_(talk) 18:04, 27 February 2008 (UTC)[reply]

At the speed of sound

If something is moving at, or faster than the speed of sound--say any of those fancy jet planes, can sound be heard by the people inside them?

My understanding (however limited) of relativity would tell me that the sound waves inside the planes would be traveling at 1,120 ft/s PLUS the rate of plane, so i think the answer is yes. BUT if that's the case, then I don't think I understand how we measure the speed of sound...

(it is also my understanding that light does not work that way, its speed is constant) —Preceding unsigned comment added by 76.118.184.59 (talk) 07:17, 27 February 2008 (UTC)[reply]

The speed of sound is measured relative to the motion of the air. Since the plane carries its own air with it, sound within travels at 343m/s relative to the plane, and everyone inside hears it just as well as if the plane were sitting still on the tarmac. If that doesn't seem right to you, keep in mind that the Earth is spinning quite fast (over 400m/s at the equator), and is hurtling around the sun even faster. We can still hear because air near the ground is relatively slow with respect to us (and the ground), and that's what's important. Someguy1221 (talk) 07:34, 27 February 2008 (UTC)[reply]

The speed of sound and the speed of light have a lot in common: like all waves, they are independent of the speed of the emitter (hence you can get something like a sonic boom on the outside of the aircraft). Sound, however, is just a compression of the air itself, so if the air is pressurized then it's going to be the same inside whatever that frame of reference is. You can't do that with light. --98.217.18.109 (talk) 13:45, 27 February 2008 (UTC)[reply]

Wires

How much copper would it take to run a hundred miles of telegraph line? --12.169.167.154 (talk) 09:57, 27 February 2008 (UTC)[reply]

At the time of the US Civil War, wire plus insulation was about 75 pounds per mile, putting the copper content around 40 to 50 pounds per mile (about 13 kg/km). This corresponds roughly with 16 AWG, and 100 miles would be around 4500 pounds of copper. — Lomn 14:06, 27 February 2008 (UTC)[reply]

Telegraph wire was not typically insulated. Air was the dielectric, with wires spaced apart from one another, and with glass insulators to insulate the wires from the crossarms of the poles. A layer of insulation would have increased the weight, requiring stronger and more closely spaced poles, and would have increased the buildup of ice, and would have increased the whipping due to wind, because of the larger cross sectional area. Insulated wire would have made sense in locations with tree limbs near the wire, and certainly cables in couduit or direct buried, as in British practice. Perhaps the Signal Corps made insulated wire standard because they did lots of temporary runs with the insulators attached directly to trees and wire run through the branches. Galvanized iron wire was strong and cheap, but heavy, high resistance, and prone to corrosion. Copper was high conductivity and light, but weak and expensive. An 1860's book 1869 book [id=2GQEAAAAYAAJ&pg=PA53&dq=telegraph+wire&lr=&as_brr=1&ei=VozFR-7OIZmYiwG6xP22CA#PPA55,M1 discusses various wire use in 1860's telegraph practice in the US and elsewhere."Compound wire," or steel core wire with a copper outer layer was liked, because the steel gave it superior strength compared to galvanized iron or copper, while the copper gave high conductivity and corrosion resistance. They mention compound wire weighing 80 to 175 pounds per mile as a good choice. Strong wire means fewer poles per mile, and fewer insulators to drain off signal strength. A 1903 book [26] says iron wire was used through much of the 19th century for telegraphe runs overland, but that galvanized iron corroded and failed in 10 or 12 years, and that soft copper was too weak to run from pole to pole, because it sagged under its own weight. It says that compound wire lost out to hard drawn copper wire, which was stronger than soft copper. This book says (p532) that 35 to 40 poles per mile was typical. P 542 mentions #14 copper (British Wire Gauge) as a typical conductor. Page 555 says the hard drawn copper wire, if 12 gauge weighs 170 pounds per mile, and if 14 gauge weighs 110 pounds per mile. Edison (talk) 16:25, 27 February 2008 (UTC)[reply]

Gain in a transistor

In genral what factors affect the gain of a transistor?Bastard Soap (talk) 11:13, 27 February 2008 (UTC)[reply]

From our Bipolar junction transistor article, the common-emitter current gain is represented by

\beta _{F}

or h_fe which is an intrinsic characteristic of a given transistor. Increasing the amplitude and frequency of the input signal will have an impact in reducing the gain of a transistor. --hydnjo talk 15:04, 27 February 2008 (UTC)[reply]

Mental illness in children

The newspapers in Britain seem to mention every week how more children are being diagnosed with mental illnesses, or are more stressed or anxious etc. Is this actually due to an increase in these problems amongst children or is it just increased diagnosis? Have any studies been done about this? Thanks a lot 81.96.160.6 (talk) 16:20, 27 February 2008 (UTC)[reply]

Thermodynamics and antimatter

If the second law of thermodynamics is correct and the total entropy in the universe is constantly increasing with time, why isn't our world full of relatively equal amounts of matter and antimatter? Shouldn't the two have become more disordered with time? Wrad (talk) 17:03, 27 February 2008 (UTC)[reply]

It is currently one of the Great Big Questions in Physics as to why there is not more or equal amounts of antimatter in the universe. See our article on Baryogenesis. To answer your question more specifically: very early on in the Big Bang matter ended up dominating over antimatter, and since then there have never been significant quantities of antimatter in the universe. --98.217.18.109 (talk) 17:14, 27 February 2008 (UTC)[reply]

(ec)You've touched on one of the most significant unsolved problems in physics—why is our observable Universe made almost entirely of matter? Where did the 'missing' antimatter go? Our articles on baryogenesis (the formation of matter in the Universe) and baryon asymmetry (why there's so little antimatter) discuss the issue in some detail.

To approach the question of 'equilibration' between matter and antimatter (the idea that some sort of 'settling' process would drive an early imbalance in matter/antimatter ratio to an equilibrium) one must note that there is no known process that allows the conversion of matter to antimatter. We can convert energy (reversibly) into equal parts matter and antimatter, but we can't bias the process to generate more antimatter (or matter). Pair production – as far as we know – always produces a matter and an antimatter particle. TenOfAllTrades(talk) 17:17, 27 February 2008 (UTC)[reply]

Temperature sensation

Is there a difference in physiological response to the sensation of extreme temperature as stimulated by actual temperature changes and as stimulated by chemical means? More specifically, would there be a difference in response to an actual cold stimulus (which for this example we will assume is not of sufficient duration or intensity to cause clinically appreciable tissue damage) and a stimulus which chemically imitates the same degree of "coldness" ( I realize this is an ambiguous term, and am just as interested in discussion of this topic as I am in a clear answer). Would these two stimuli send identical signals through the spinothalamic tract? Would the efferent signals be identical? Without any way to measure temperature, would there be any way to distinguish between the temp. cold area and the chem. cold area? Does a chemical cold stimulus cause an increase in temperature of the affected tissue? And finally, is the situation reversed for temperature and chemical heat stimuli? Sorry for the compound question! Tuckerekcut (talk) 18:00, 27 February 2008 (UTC)[reply]

February 21

Environmental Effect of Al Gore

Explain about the working of nMOS super buffers in VLSI?

Rabbit skeleton conservation

press machine

starch vs. sugar

Is the universe 100% logical and 100% consistent 100% of the time?

Building a voltaic stack

Body wastes H2O?

February 22

What else is there?

Belated bruise

3600rpm 1000 HP electrical motor. Need bibliography. Vibration

Power factor in electric circuit

Old voice recordings

Modem

Electromagnet

Paper Clip Capacitor

Medicine

answers plz (refrigeration vs. air conditioning)

Chemical reaction question

is it two seconds or four seconds to moon and back?

Unrelated to the original question

Purple veins

What makes protiens

February 23

moon in past

Ideas for prosthetic communication devices for 'locked in' syndrome

How Composite Quantum System Relates to Tensor Product?

worst animals

Built-in Radio

How did water form?

Solving scrodinger equation for particle in a potential well

Strange sun halo

are silicone implants safe?

Can glasses induce oil secretions?

tissue

A kind of gambling machine

Grapefruit seeds

February 24

Here comes the sun

Breitling Orbiter 3

Human genome conservation with dogs

RNA amplification

Question about Salmon (but don't Rushdie answer)

Photon bouncing?

Boiling oil

Salinity of saline solutions

Other salts

Coriolis Effect

Moon and Sun having the same apparent size

Weird Taste and Smell lingering days after taking Advil Cold and Flu

February 25

Alternate method of boiling

Electric Car

Why did the use of Greek fire stop?

earthworms

Purchasing Explosives

color

Role of Urea in concentrating uring

MORE PHYSICS MAGZINE QUESTIONS,FROM THE PHYSICS MAGAZINE GUY

February 26

the ocean

food processoring

Taigas

Plugging both speakers in to one channel of a preamp

Unidentified bathroom fly or moth

"Shut-in" oil production

knee surgery

Does hand sanitizer kill viruses?

SRS statistics

Harmonics (?) with RF emissions causing lights to go out

Engineering(Naval Arts) - detrimental effects on ship cause by twisting propulsion engines

Killing the Bass

Dream More...

Faster Hair

Shadow Dexterous Hand

February 27

Alcohol Rub

How deep