Revision as of 22:28, 7 December 2006

Reference Desk

December 4

Docking in orbit

How do 2 spacecraft in the same planetary orbit achieve docking when they are initialy far apart?--Light current 00:43, 4 December 2006 (UTC)

• I'm not sure if it's the only way, but the simplest at least is for one of the spacecraft (call it A) to make a retro burn to slow itself down, which will raise its orbital altitude and increase its orbital period. The other spacecraft (B) will eventually 'catch up' with A, at which point A can make a positive burn to increase its speed again, lowering its altitude back to the original level and matching the speed of B to achieve rendezvous. This may seem a bit counterintuitive, and is one reason why it's really difficult to perform a rendezvous manually. --YFB ¿ 01:18, 4 December 2006 (UTC)

• You have retrograde and posigrade reversed here. The first burn should be a posigrade to increase velocity, raise apoapsis and increase the period. The second burn is retrograde to decrease velocity, lower apoapsis and decrease the period back to match B. Other than that, it's about right. Of course all of this assumes that the two spacecraft are initially in the same orbit, with A ahead of B. If B is ahead of A, reverse the procedure. Also note that both burns have to occur at the same point (periapsis for the burn described) in order to return to the same orbit. Finally, if the two orbits are not the same initially, this all gets a lot hairier, and phenominally complicated. --anonymous6494 06:39, 4 December 2006 (UTC)

Apoapsis? Ah I was just interested in circular orbits. Forgot to say that.--Light current 08:17, 5 December 2006 (UTC)

I thought if you made a positive burn it would increase your 'altitude' . Is that wrong?--Light current 08:26, 5 December 2006 (UTC)

Correct. A posigrade burn will raise your orbital altitude, but one of the fundamentals of astrodynamics is that if you perform a transfer between any two orbits, the two orbits must coincide at the point where you made the transfer (assume an implusive (instant) transfer). So your altitude is the same at the point where you made the posigrade burn, and greater than before everywhere else. The same principle applies to the transfer you initially asked about. The initial orbit is circular, but A's transfer orbit (between the two burns) is elliptical. The burns occur at periapsis of the elliptical transfer orbit.--anonymous6494 23:25, 5 December 2006 (UTC)

Hmm I think I understand and I think it makes sense to me. If Im behind you, I put the brakes on to catch up distance then accelerate to regain height. Right? --Light current 23:48, 5 December 2006 (UTC)

Bullseye. -anonymous6494 16:04, 6 December 2006 (UTC)

Advanced Motion

I need something advanced about motion (not that advaned, but medium-ly advanced, not basic) that I can explain in 2 minutes or less. Thanks for any ideas. Cbrown1023 01:04, 4 December 2006 (UTC)

• How about Newton's three laws of motion? If you're good at explanations you should be able to do this at a reasonable level of detail in two minutes. Or isn't that 'advanced' enough? --YFB ¿ 01:20, 4 December 2006 (UTC)
  • It is a good idea, but we already are studying those... I've been thinking for a while and can't seem to come up with a good idea... Cbrown1023 01:22, 4 December 2006 (UTC)
    • I think I'm going to do Motion capture. Cbrown1023 01:45, 4 December 2006 (UTC)

• Sounds like a good choice - best of luck :-) --YFB ¿ 02:02, 4 December 2006 (UTC)

Dots in eye w/o glasses - explaination/image?

Hi! I remember that a while ago I had seen an image and a short explaination on why people with Myopia see small moving dots and lines when looking at a bright light without glasses, but searching, I cannot find it. Does anyone who is familiar with the phenomenon know where to find such an explaination? Thanks! 69.253.41.139 01:26, 4 December 2006 (UTC)

Do you mean Floaters? risk 03:20, 4 December 2006 (UTC)

Under the right conditions, you can also see the red blood cells circulating in the capillaries of your retina. The effect is most pronounced if you're staring into a deep blue, featureless field (such as a cloudless sky). The Exploratorium in San Francisco has a device that demonstrates this effect very clearly; other science museums may also have copies of this gadget.

Atlant 14:17, 4 December 2006 (UTC)

(Blue field entoptic phenomenon)

Speed in space

I'm having trouble understanding the concept of speed in outer space. I mean, if you're in a spacecraft in interstellar space on the other side of the galaxy, is there any way to measure what speed you're traveling at? I know that speed is defined relative to points of reference, which makes me wonder if speed has much meaning here. But on the other hand, the speed of light is (usually, I think) a kind of definite limit on how fast you can go...so I was thinking, could you (theoretically) measure your speed against a beam of light that you shine forward? If you could (somehow) measure that the light you project is traveling away from you at 539,626,424.4 km/h, then could say that you're traveling at .5c, wherever in space you're located? Or if the light is traveling away from you at 1,079,252,848.8 km/h, could you say that you are "stopped"? Or is this just all nonsense? Thanks for any help you could offer. --Lazar Taxon 01:28, 4 December 2006 (UTC)

Well, I don't think so - light always travels at C relatve to the observer - so that may not work. However, a pulse of light "launched" - for lack of a better term - at a stationary object can easily calculate distance, then repeating that after a set amount of time can calculate speed. 69.253.41.139 01:31, 4 December 2006 (UTC)

You do have a good point. I'm just having trouble reconciling the fact that all speed is relative, with the fact there is an absolute speed of light. --Lazar Taxon 02:14, 4 December 2006 (UTC)

Great, now I've gotten a headache :P As you said in your first post, speed may not have much point in outer space, except when relative to sometihng - such as the international space station or the moon, both of which are "moving" relative to the earth and to the sun. I think that the best way to do that, would be similar to sonar, shoot something at your target and use time to measure distance. 69.253.41.139 02:34, 4 December 2006 (UTC)

Light as a sonar would not work. Speed of light has some interesting reading. The hardest concept to grasp is that light does not really have an analogous physical thing that makes it easier for us to imagine, you have to really use all your conceptual power to even begin to grasp it. Light has constant speed for ALL frames of reference, it doesn't matter if you are travelling at 0.5c and you fly past someone and turn on your headlights, to you it will look like the light will shoot away from you at the speed of light, and to the 'stationary' observer it will look like the light will shoot away from you at the speed of light too!!! It's crazy. If you are travelling forward at half the speed of light and the light is shooting out in front of you, in one time unit according to the frame of reference the light has travelled one and a half distance units, but according to the 'stationary observer' the light is shooting out in front of you STILL at the speed of light even from their point of view. So in one time unit it has only travelled one distance unit according to them?!?? wait for your mind to melt. We know the speed of light is constant, what is speed? It is V = d/t (distance over time). In normal observable physics, what we see day to day, time and distance are constant for all frames of reference, and SPEED is variable, if you change either t or d you simply change V, but with light V is the constant! Therefore, if you change d, like we did in the above example, the only other variable you can alter to balance the equation is TIME it self, time changes depending on your frame of reference! crazy business! Vespine 03:03, 4 December 2006 (UTC)

Another interesting concept is if you are traveling in your car and pass someone near the speed of light, and turn on your headlights, you will completely fry him with the brand new X ray emitters you used to call headlights. --Tbeatty 03:12, 4 December 2006 (UTC)

You've basically touched upon the crux of the (special) theory of relativity, which states that even though all speed is relative, the speed of light is not relative. So if I'm on a space ship speeding away from earth, and you're on earth, and we both measure the speed of the same beam of light, we we'll both find c. You might think, well, then if I'm traveling at some speed v relative to the earth, near the speed of light, and someone else is traveling at speed v relative to me, then isn't he traveling at v + v relative to the earth? The thing is that simply adding speeds together like that isn't allowed in the theory of relativity. The actual equation makes sure that as you go faster, you approach the speed of light, but you never reach it. If I'm traveling 0.5c relative to the earth, and somebody is traveling 0.5c relative to me, he's actually traveling 0.75c relative to the earth (NB: these are probably not the actual numbers, but that's the idea). The article on the special theory of relativity has more info. risk 03:02, 4 December 2006 (UTC)

Instead of a flashlight, pick a star and a known hydrogen emission. Speed of light is constant so the difference in kinetic energy between the star and observer is translated into frequency. This is how astronomers have determined that the universe is expanding and everything is moving away from us. --Tbeatty 03:08, 4 December 2006 (UTC)

Phenotypic ratio

What is a phenotypic ratio? -- THLR 01:54, 4 December 2006 (UTC)

In biology a phenotypic ratio is the ratio between two or more phenotypes. A phenotype is the result of a certain gere - blue eyes, or brown hair. This is similar to, but seperate from, a genotypic ratio. If I have 4 offspring with the genes of Bb Bb bb BB for eyes - b means blue and is not dominate, B is brown and is dominant - my genotypic ratio is BB:Bb:bb = 1:2:1, however my phenotypic ratio is Brown:blue 3:1, since a Bb is Brown eyes, not blue. ST47Talk 02:04, 4 December 2006 (UTC)

Chemistry Molar Question

What does 6M HCl mean? Like I know you say it 6 molar HCl, but what does the molar mean, and how high can the xM (replace x with a number) go? —Preceding unsigned comment added by Darkleg (talk • contribs)

In this case, "mole" refers to Mole (chemistry), specifically Molar concentration. -Fsotrain 02:26, 4 December 2006 (UTC)

See also Concentration#Molarity. --David Iberri (talk) 02:30, 4 December 2006 (UTC)

The concentration can go fairly high; it depends on the substance and how soluble it is. 6M is fairly concentrated. Normally in chemistry classes you deal with concentrations between 0.01M and about 6M. BenC7 02:47, 4 December 2006 (UTC)

For the specific case of hydrochloric acid, the limit is about 12M or 13M, because that's "fuming" hydrochloric acid, which means hydrogen chloride gas is constantly coming out of solution. Although we usually don't talk about the "concentrations" of pure solids or liquids (because they don't effect chemical equilibrium), they're still defined, and the concentration of pure iron is 140 mol/L. —Keenan Pepper 06:06, 4 December 2006 (UTC)

Anatomical name for "weenis"

I've heard that the skin on your elbow is know as a "weenis". Is this the real name or is just a neologism? Imaninjapirate 03:54, 4 December 2006 (UTC)

neologism. --froth 05:38, 4 December 2006 (UTC)

A quick Google for "elbow skin" brings me to a Google Answers question with a surprisingly large price. No answer was ever accepted, but I like the suggestion of "olecranal skin" or "olecranon skin". -- Plutor  13:49, 4 December 2006 (UTC)

Fastest Piston Powered Aircraft

What was the fastest *piston* powered aircraft ever built? Include prototypes and xplanes if that helps Spencer McGrew

A modified F8F Bearcat called the Rare Bear (528.33 mph or 850.26 kph), according to the article. Clarityfiend 05:34, 4 December 2006 (UTC)

Really quick question

How do you pronounce the name of the antibiotic coformycin? Is it /'koh-fuhr-,mii-s^n/ or perhaps /'koh-,fawr-'mii-s^n/ (pardon the idiosyncratic phonemic transcription? Thanks, anon. —Preceding unsigned comment added by 162.83.150.164 (talk • contribs)

With a midwest accent (or lack thereof) I would say Ko-for-mysin with the accent on the first syllable, and the "for" pronouned as in "go-for-broke" but suspect the exact sound of the middle syllable would vary by the speaker's accent. alteripse 05:11, 4 December 2006 (UTC)

Since it's found in Nocardia interforma it's reasonable to assume the pronunciation is derived from the organism, making the for- part of the word form or forma --13:54, 4 December 2006 (UTC)172.145.44.11

I would say k'form-a-sin (conform to sin). Theavatar3 18:14, 5 December 2006 (UTC)

No of Universe

Are there exactly 10^50 number of atoms in the universe??Any idea on how to get to that conclusion?? And what about the probable number of universes that could have been formed with that many atoms??

Bit of a lame answer to the last question: one. The universe is all there is, so there can only be one. DirkvdM 09:39, 4 December 2006 (UTC)

Atom suggests there are about 10 atoms in the universe. This is a ballpark guesstimate only; google for number of atoms in the universe for different estimates and methods of estimation. Nobody really knows; but if you estimate the number of galaxies, average number of stars in each, average size of stars, you end within a factor of 10 from that number. Weregerbil 12:48, 4 December 2006 (UTC)

Magnetism

We know that we are having a net velocity as we are travelling across the universe.So why not any charged particle emit magnetism if it is kept stationary on earth??

Because it's all relative! In this case, it's important to remember that magnetic fields are only detectable from the relative motion of charged particles. If, from your point of view, a charged particle isn't moving, then you won't detect a magnetic field (though you will detect an electric field). But if you were elsewhere in the universe, moving relative to the Earth, then you would detect a magnetic field coming from that particle. Confusing Manifestation 11:16, 4 December 2006 (UTC)

Coeper pair

Any idea if a photon forms a positron/anti positron coeper pair??

Did you mean cooper pair?87.102.32.183 09:29, 4 December 2006 (UTC)

And by "anti positron" do you mean, um, an electron? Anyway, from looking at Cooper pair, it seems to me that you can't have them with an electron and positron, because they depend on the polarization of the ion lattice attracting another negative charge. Electrons and positrons already attract one another, but you certainly couldn't have positrons in a normal-matter superconductor. Perhaps you want to look at pair production? --Tardis 17:53, 4 December 2006 (UTC)

tritium

Since tritium is a non-gamma ray beta emmitter when used in the place of hydrogen to make sulphuric acid does it give the acid a negative charge and if so is this charge sufficeint to charge a lead acid cell? Adaptron 10:45, 4 December 2006 (UTC)

There is no creation of charge in this reaction. The opposit charge is also present and will lead to neutralisation. With a half life of 11 years the recharging would take some time. —The preceding unsigned comment was added by 134.76.234.75 (talk • contribs).

Would "neutralisation" result in a thermal increase? 71.100.6.152 08:33, 5 December 2006 (UTC)

There are power sources which use the beta decay of tritium to generate electricity (see Betavoltaics), but not in the way you suggest, which would be grossly inefficient. —Keenan Pepper 16:20, 4 December 2006 (UTC)

Oxygen Generation

I heard somewhere that the great grasslands of the World contribute more oxygen to the Planet than all the forests, is this true?

I would think the relative land areas of each would be the most important factor. Perhaps, if there are now more grasslands than forest due to human deforestation, that might now be true. StuRat 12:43, 4 December 2006 (UTC)

decomposition of phosphene

Dear Sir/Madame,
I would be most obliged if you could give the chemical equation for the following reaction:

Phosphene when decomposed gives phosphorous and hydrogen

Sincerely, Sruthi

assuming white phosphorus as product:

4PH₃ --> P₄ + 6H₂

Cambrian Man - ?

Evidence of a fully fossilized 500 million year old fully formed Human Being, unearthed in modern day Ethiopia. This 'Pre Cambrian Man' as he's been called is a fully developed homo sapien, and predates any human remains yet known. How do you explain this discovery without conflicting evolution theory? - User:CC clamb

Useful answer: This thing is called a Australopithecus afarensis, not a homo sapiens. Friday (talk) 01:25, 6 December 2006 (UTC)

May we conflict any other theory (in physics, for example)? –mysid☎ 13:59, 4 December 2006 (UTC)

Can you please provide us with a link so we know whether this "evidence" is from some rabidly anti-science creationists or from legit scientists ? StuRat 14:13, 4 December 2006 (UTC)

I find zero relevant hits from Google for "Pre Cambrian Man", nor for Google's suggested "PreCambrian Man". The few hits which do exist for the term seem to be using it to mean "prehistoric man", which is certainly not the same thing. User:Zoe|(talk) 19:41, 4 December 2006 (UTC)

Does not exist. --Zeizmic 15:07, 4 December 2006 (UTC)

You may not understand the word "theory". "Evolution theory" is not a set of immutable facts. See Theory#Science. Friday (talk) 15:26, 4 December 2006 (UTC)

Do you guys remember what existed before the Cambrian? All the life forms were lower than trilobites. This is nonsense. alteripse 22:12, 4 December 2006 (UTC)

The sensible answer to the crazy question is of course: time travel. Some far future human goes sight seeing in the distance past and gets his face sucked off by Opabinia regalis. Then 500 million years later the fossil is discovered, but fearing a creationist nightmare and/or a temporal paradox, scientists tell no one save for a single posting on Misplaced Pages that no one will believe. Dragons flight 22:28, 4 December 2006 (UTC)

A Wikipedian sucked off someone's face? bibliomaniac15 02:54, 5 December 2006 (UTC)

. User:Zoe|(talk) 03:03, 5 December 2006 (UTC)

And what, pray tell, my dear Zoe, does the discovery of a mechanical device from the time of Eratosthenes, who accurately determined both the size of the Earth and the distance to the Moon, have to do with the subject at hand? B00P 23:41, 5 December 2006 (UTC)

It's evidence of time travel, of course.  :) User:Zoe|(talk) 03:44, 6 December 2006 (UTC)

social psychology

Social Psychology cannot explain all our social problems. Discuss

Some students cannot figure out the meaning of the sentence at the top of this page that states Do your own homework. Discuss. --Kainaw 15:54, 4 December 2006 (UTC)

Reference Desk in Misplaced Pages would not do your homework for you. Discuss 202.168.50.40 23:00, 4 December 2006 (UTC)

I majored in psychology. I found that social psychology was the most useless, tautological course of all. Which, of course, is the most useful thing of all to learn, for someone studying psychology.

Psychology teaches you beautifully how one person will act. Try to extraopolate that to a group of people, and you're left high and dry. As we live in a world of considerably more than one person, studying psychology to begin with means you are already high and dry.

That said, Nietzsche did not err when he said something to the effect of 'psychology is the mistress of all other disciplines'. It coherently answers questions like, 'why study botany at all?' Theavatar3 18:18, 5 December 2006 (UTC)

Fastest piston warplane

What was the fastest piston powered aircraft in millitary service? Spencer

Scroll up - this question as asked and answered. --Kainaw 16:11, 4 December 2006 (UTC)

The de Havilland Mosquito is also a noteworthy fast piston aircraft, in that it did extensive service as a reconnaisance, plane, fast bomber, and night fighter. It cold do 415 mph at 28,000 ft (668 km/h at 8,535 m) It could have theoretically completed 2 round trip bombing runs while the slower heavily armed bombers were doing one. Its variant the de Havilland Hornet would do 472 mph. Edison 18:34, 4 December 2006 (UTC)

This second question is a little different. The Rare Bear was privately owned. According to Dornier Flugzeugwerke#History, the fastest fighter in WWII was the Do-335 (474 mph, 763 kph). Clarityfiend 19:49, 4 December 2006 (UTC)

Hmmm...according to de Havilland Hornet, its prototype topped out at 485 mph. Clarityfiend 03:37, 5 December 2006 (UTC)

Not that the question said "in military service." Perhaps the prototype did not have to carry equipment which was necessary for military service (giuns and ammo? long range vacuum tube radio and power supply? Navigation equipment? life raft?). In modern military planes, they are hotrods capable of fast climbing until the avionics and weapons are added. Most planes can also go very fast in a dive, but that doesn't count. Edison 16:50, 6 December 2006 (UTC)

plants

what is the worlds slowest growing plant

Petrified wood. But Bristlecone pine is right up there. Atlant 16:54, 4 December 2006 (UTC)

Huh, how can you consider petrified wood, a type of fossil, to be a "growing plant"? -- AJR | Talk 17:54, 4 December 2006 (UTC)

That was a joke, the second answer is the serious one. StuRat 18:01, 4 December 2006 (UTC)

And, of course, I offered an answer that actually describes "the world's oldest multicellular, non-cloned plant", which isn't exactly what was asked, but as I said, definitely rates "up there". But it's entirely possible that the real answer is some sort of cryptobacteria (bacteria in a cryptobiotic state).

Atlant 18:23, 4 December 2006 (UTC)

Yes, and some seeds can stay dormant for many years before growing at all; that certainly qualifies as slow growth. StuRat 19:50, 4 December 2006 (UTC)

My guess would be the trees that live in the pygmy forests on the west coast of CA near Mendicino. They grow in nutrient poor soil, due to leaching. Some are over one hundred years old and as small as a few feet tall with trunks as small as 3cm diameter. Another candidate might be the bristle cone pines. Some live to 4000 years old and they have very very hard wood. This means their annual rigns are very close together and thus have very slow growth. Use google to get more info. David D. (Talk) 21:52, 4 December 2006 (UTC)

Electricity Efficiency

Why do power stations transfer electricity at 50hz to achieve the highest efficiency and how does this frequency maintain that? I would also find it extremely useful if a table with voltage (in and out of transformer), current(in and out of transformer), power in (to transformer), power out (of transformer) depending on frequency of electricity could also be supllied. thank you.

They don't all transfer power at 50 HZ, some transfer power at 60 HZ, a few countries even use a mixture of the 2 frequencies --172.147.216.150 16:57, 4 December 2006 (UTC)

50 or 60 Hertz was a reasonably "comfortable" frequency representing a good compromise between several competing needs:

• the efficiency of transformers (which, for crummy, low-tech materials tends to improve at lower frequencies)
• the size of transformers (which get a lot smaller with higher frequencies)
• Reactive losses on power lines (which rise with frequency)
• The ability to build practical induction and universal electric motors.
• Various industrial processes (such as electric arc furnaces, electroplating, etc.) that would prefer DC but could use low-frequency AC

Nowadays, in the high-tech world, the operating frequencies of devices are becoming completely decoupled from the mains frequencies, though, and you can see the result:

• Long-distance transmission is going to DC (see High-voltage direct current)
• While transformation goes to ever-higher frequencies (with hundreds of kilohertz now common in switched-mode power supplies
• While motors now generate their own frequencies (see Brushless DC electric motor)

By the way, there's no good reason to choose 50 versus 60 Hz; that difference is just an artifact of competing equipment vendors trying to lock each other out of various markets.

Atlant 17:10, 4 December 2006 (UTC)

As to how the frequency is maintained, think of the electrical utility system as a car going at a certain speed, in which the gas pedal must be pressed harder to maintain that speed when the car goes up a hill. The steam from the boilers spins the turbines driving the generators. If load is added, as by customers turning on lights, ovens, and air conditioners, all things being equal, the frequency would decrease because of the imbalance between generation and load. The governors or speed controls at the generating station sense the added load and frequency drop, and open the steam valves to allow more steam to the turbine to maintain the frequency, just as in a car the driver (or the cruise control) sends more gas to the engine to maintain the desired speed. If the generator and turbine system are maxed out, or if several generators trip off the system, then the frequency will continue to drop. Low frequencies can destroy the generator at certain resonant frequencies, and will destroy motors. Ovespeed will also destroy a generator. There are protective relays to trip it offline if either condition occurs. In historic cases in the 1940's utility frequencies dropped from 60 to 45 hz, destroying all large connected motors. In the 1965 New York power blackout, during the progressive collapse there was ultimately a huge overload on the few remaining generators in the city, causing a frequency drop from 60 hz to (if I recall correctly) 55 hz before underfrequency relays on that generator tripped it offline. To avoid recurrences of this, utilities have installed underfrequency relaying systems to detect such a progressive decline in frequency and automatically shed load to restore a balance between load and generation, and to maintain the frequency to acceptible levels. This reduces the human element from hesitating when a decision to drop load has to be made within a few seconds. The actual system frequency often drops (less than 1 Hz) during periods of heavy load, causing a synchronous clock to fall as far as 30 seconds behind the correct time. When the load drops, or more generation is put on line, the frequency is set slightly above nominal to catch up the synchronous clocks. The powerline frequency is a far less accurate frequency standard than a quartz clock. Edison 18:51, 4 December 2006 (UTC)

50Hz or 60Hz was chosen not because of efficiency but because of the lightbulb. If the frequency is too low then the light from the lightbulb would flicker or rather the flicker would be noticed by humans. 202.168.50.40 20:40, 4 December 2006 (UTC)

Incandescent light bulbs do not flicker at line frequency. Melchoir 01:15, 5 December 2006 (UTC)

Which was the previous poster's point. On 25 Hz power, say, they would. (Incidentally, there is still some 25 Hz generation at Niagara Falls -- see utility frequency. This dates from way-back-when and is now only for industrial use, big motors that nobody wants to convert, but it was in residential use until around 1960.) --Anonymous, 08:00 UTC, December 5.

GSM interference with speakers/amplifiers

I've noticed that GSM (and AMPS) phones sometimes cause a sporadic humming interference with amplifiers and computer speakers (especially when transmitting). Since they transmit in the 800-1900MHz range, how are they producing interference in the 20Hz-20kHz range? Oh, no need to dumb down the answer for me. --Dgies 18:16, 4 December 2006 (UTC)

Rectification, most likely. You're probably hearing the envelope of the carrier wave.

Atlant 18:18, 4 December 2006 (UTC)

Signals trapped inside a metal case can cause humming at different frequencies, but I've found the common culprit to be cheap speakers. My wife had a pair that, even if they had no power to them and weren't plugged in, would pick up transmissions from the shrimp boats off shore. I threw them away and got better speakers and the problem went away. --Kainaw 18:20, 4 December 2006 (UTC)

So a higher quality design would have a low-pass filter before the amplifier I guess... --Dgies 18:39, 4 December 2006 (UTC)

The first range of frequencies you mentioned is the frequency of electromagnetic radiation (in this case radio waves) while the second is the frequency range of sound waves (vibrations). the two are completely distinct.. there's no reason why electromagnetic waves interfering with your speekers should produce sound waves of the same frequency.

No, Atlant explained it correctly. 1.8GHz radio waves induce voltage in the amplifier, which is fed into a rectifier. Rectification (either full or half-wave) has the effect of mixing the cell phone signal with a square wave at the frequency of its carrier. Therefore the original modulation of the radio signal has been mixed down to baseband and when fed into the speaker's voice coil, will produce audible sound. So in an ideal amplifier, you need a bandpass filter on voltages being fed into the rectifier unless you want to get mixer effects. --Dgies 22:08, 4 December 2006 (UTC)

I've examined the waveform of the interference, and the "1" squares of the square wave last exactly for the duration of one TDMA timeslot; the "0" phase lasts for seven slots (the TDMA frame in GSM has a total of 8 timeslots). It made me think the interference is mostly due to TDMA; the mobile phone switches the transmitter on and off at a frequency which is in the audible frequency band. –mysid☎ 11:58, 5 December 2006 (UTC)

Global Warming

Would it be a good (or feasible) idea to combat global warming by collecting large amounts of carbon dioxide (and other Greenhouse gases) from factories and such like, putting them in containers, taking them into space and releasing the gas there instead of on Earth?81.158.81.209 20:42, 4 December 2006 (UTC)

No, the pollution caused by the rocket would far outweigh that removed by the rocket. And, carbon dioxide isn't bad, so long as it's not in the air in excessive quantities. A better approach is to use plants (like algae) to convert it to carbon and oxygen. StuRat 21:37, 4 December 2006 (UTC)

Acoording to , that wouldn't be a good idea either. They say that increasing the levels of algae and plankton enough to stop global warming would completely through off the underwater ecosystem and could potentially kill off every living thing underwater. On the plus side, it wouldn't cost too much money and could be started immediatly if the UN decided to do it. They say that the best combination of feasibilty, price, and risk to our health is actually like 81.158.81.209's... take all of our CO₂ emmissions and storing it underground. Paragon12321 22:39, 4 December 2006 (UTC)

A better approach would be to lock it up in rocks (like limestone) See Carbon cycle 8-(--Light current 23:00, 4 December 2006 (UTC)

More specifically, see carbon sequestration. --Tardis 23:27, 4 December 2006 (UTC)

Well.. to be honest I was thinking more of the LONG term carbon cycle that involves absorption into rocks (maybe by sea shells etc), submerging of the rocks by the sea, subduction of the rocks, melting of the rocks and finally spewing of molten rock from volcanoes along with Gt of CO2. But apart from that, carbon sequestration probably has a minor role 8-)--Light current 01:19, 5 December 2006 (UTC)

CO2 concentrations in the atmosphere is a tiny component. Build lots of nuclear power plants to turn it into diamonds and oxygen. --Tbeatty 23:37, 4 December 2006 (UTC)

Man (or woman) cannot live by diamonds alone! 8-)--Light current 01:14, 5 December 2006 (UTC)

Grow trees, cut them down and throw them in the sea or somesuch place! Where will we need to put them to prevent their locked-up carbon from getting into the atmosphere? Maybe making more of our funiture out of wood since it's gonna end up in a land-fill anyway... --Username132 (talk) 02:07, 5 December 2006 (UTC)

We have an excellent discussion on carbon sequestration going on at physicsforums right now. I highly recommend it for the inquirer, and readers. X (DESK|How's my driving?) 02:57, 5 December 2006 (UTC)

Mass, Volume, or Charge Times Distance

Is there any measurement that is "mass times distance", "volume times distance", or "electrical charge times distance"?The Anonymous One 23:29, 4 December 2006 (UTC)

Do you mean moment? --Tbeatty 23:39, 4 December 2006 (UTC)

No. Moment is force times distance, not mass, volume, or charge times distance.The Anonymous One 00:30, 6 December 2006 (UTC)

You would simply call it gram meters or litre miters etc.

Fluorescent light with motion sensor

I have a fluorescent light that worked fine. I put a motion sensor on it and now, instead of lighting properly, it flickers. The instructions for the motion sensor say that I need a balast for it. The fluorescent light has a balast in it - or it wouldn't work in the first place. Does anyone know why this problem occurs and the proper way to fix it? --Kainaw 23:48, 4 December 2006 (UTC)

You perhaps already thought of this and it's an unlikely solution but is the motion detector sensing the flicker of the light? What happens if you put your hand over the sensor so it can't detect the flicker? (Can't offer any electrical advice, sorry) --Username132 (talk) 00:14, 5 December 2006 (UTC)

The motion sensor probably has a thyristor or triac switch in the output. These are not intended to operate fluorescent lights. Presumably you are not using any sort of ballast for the motion sensor? I dont know why it would need one but there you go. Are you reading the instructions properly? Also, you cant use dimmers on fluorescents for the same reason--Light current 00:26, 5 December 2006 (UTC)

Sorry, but it can't be done. Most timers can now handle fluorescents, but the in-switch motion detectors can't...I've tried. :( One day they might be able to do it, but I would then expect to see a big advertising splash. --Zeizmic 01:04, 5 December 2006 (UTC)

I don't know if I'm thinking of the same thing, but at university, when we walked along the hallway in halls of residence, the strip lights (fluorescent, right?) would come on (albeit with an annoying delay). --Username132 (talk) 01:19, 5 December 2006 (UTC)

Maybe but I bet they were relay activated. --Light current 01:21, 5 December 2006 (UTC)

Then can Kainaw use a relay or is that impractical? --Username132 (talk) 01:38, 5 December 2006 (UTC)

I was rather stupid. I should have mentioned that it flickers when it should be off, but lights up when it should be on. Looking at these answers, I think that the sensor is letting enough electricity through in the "off" position to get a blink of light every few seconds. --Kainaw 02:10, 5 December 2006 (UTC)

Well really, fluorescents shouldnt be switched on and off like that! They take some time (depending on the starting circuit) to strike anyway.--Light current 02:15, 5 December 2006 (UTC)

As mentioned, there are very expensive motion detectors designed specifically for fluorescents, but the cheap in-switch types can't handle it, since they must maintain a small current through the system to keep active. --Zeizmic 13:11, 5 December 2006 (UTC)

Lots of "intelligent switches" of various types (motion detectors, darkness detectors, X-10 remote control devices, and the like) all have a function whereby they detect when you flip the manual switch on the external load and they then apply full power. That is, if they're controlling, say, a table lamp, you can turn the table lamp on from the lamp's switch no matter whether the intelligent gadget was thinking that the lamp should be "on" or "off". The way they do this is to attempt to pass a trivial amount of current through the load at all times. When you close the switch on the table lamp, this "test current" can pass through the load, the intelligent device detects that, and turn on the full current.

This worked great for incandescent light bulbs where the test current caused no visible effect. But for some modern devices, the test current is enough to actuate the lamp, either continuously (for LED lamps) or sporadically (for your flourescent lamp with an electronic ballast). For some LED Christmas lights that I was playing with on an X-10 controller, they were nearly as bright with the controller "off" as they were with the controller "on".

There are several solutions, none great:

• Modify the intelligent device to remove the "test current" feature. This voids the warranty on the device, risks electrocution for you and the burning down of your house unless you know what you're doing, etc.

• Use an intelligent device that doesn't include this feature

• Use a relay as an intermediate control device. Same caveats as for modifying the intelligent device.

Atlant 14:14, 5 December 2006 (UTC)

December 5

List Of Latin Genus And Species

I'm looking for a list of Latin names of critters in the form of Genus species that might be used to enable a bot to italicise all such phrases and ensure that they are capitalised at, and only at, the beginning. --Username132 (talk) 00:05, 5 December 2006 (UTC)

human pathogen sizes

I'm comparing the diffusion of various pathogens and am not able to find the sizes of these bacteria.

1. Is there any way to find out the size of the largest human pathogen ?

2. Is there any place online where I could find some indication of size for various human pathogens (like an online book that would just list them with indication of sizes )

3. If the previous 3 can't be answered, where could I find indications of sizes for some (ideally all) of these?

Salmonella

Staphylococcus aureus

Streptococcus pneumoniae

Streptococcus pyogenes

Helicobacter pylori

4. is there anywhere on the net where one could find the diffusivity of the largest pathogen or any of the pathogens mentioned above ?

teo

The largest pathogens (if looking at all disease causing things) are parasitic worms. As for your bacterium sizes, I can't find many. I'll be looking, but so far, I can't find any good answers. bibliomaniac15 02:51, 5 December 2006 (UTC)

In terms of 3, you could take a look for photomicrographs of the bacteria with scale bars Nil Einne 17:31, 5 December 2006 (UTC)

There's a range of sizes for each of the organisms, depending on factors like growth conditions and strain. But here are some representative sizes from the web.

Salmonella 2 microns by 0.5 microns

Staphylococcus aureus 0.7 microns

Streptococcus pneumoniae 0.8 to 1.0 micron

Streptococcus pyogenes 0.6 to 1.0 micron

Helicobacter pylori 1 to 5 microns

E. Coli 2 microns

As a suggestion, try a Google search with the organism's name and "microns" and in most cases you'll see some answers. - Nunh-huh 21:20, 5 December 2006 (UTC)

When did Laodicea (or area) discontinue shipments of Collyrium?

Background: It is well established that a collyrium (eye salve) was manufactured in Laodicea. The New Testament -- Revelations 3:18 refers to this collyrium or eye salve. The city had a medical school and was a banking center.

"This Pheygian powder was apparently applied to the eyes in the form of a doughy paste". Varrious texts and other books provide varrious details. The books which I have looked at so far give very, very little further information.

Present Quest: I am preparing a history of the development of this product. Can you add to my store of knowledge?

disease/sickness

what is hydrocaphlus? (something connectting to the brain)

Consult our article on hydrocephalus. Come back if there are any questions you have that are not answered in the article. :) --Username132 (talk) 01:36, 5 December 2006 (UTC)

Another term for this is : Water on the brain but the cure is a little more complicated that a 'tap on the head' 8-)--Light current 01:51, 5 December 2006 (UTC)

Genetic similarity between the sexes

Hi,

I know that chimps and humans are (genetically) 90-something percent similar, but how similar are human males and females, genetically? I know that males have an X and a Y chromosome while females have 2 X's, but how much in percent would that be? Does it even make sense to ask how similar males and females are?

Thanks (74.96.217.202 01:45, 5 December 2006 (UTC))

I think it depends on the definitions you take (percentage of matched nucleotides or percentage of matched genes). The article on X chromosome says that an X chromosome is worth 2.5% of the human genome. Since guy are usually lacking one X chromsome, might we say that there is a 97.5% "match" (in terms of genes, not alleles (since alleles wouldn't make sense)) between men and women? Then again, since men do have one X chromosome with all its associated genes, maybe we should be looking at what the women lack, the coveted Y chromosome! The article tells us that the Y chromosome has a piffling 83 genes compared with the X chromosomes 1000. At about 8% of the 2.5% of the X chromosome we have 0.2% of the total human genome - which I would like to propose as my final answer. :) --Username132 (talk) 02:00, 5 December 2006 (UTC)

(added after edit conflict with Username132) All the chromosomes that men and women have in common – all but the Y chromosome – are identical in men and women. (Okay, they're not strictly identical—there will be some differences from one individual to another. Different alleles of particular genes will be inherited, there will be the odd mutation, etc. But looking solely at those chromosomes, there's no way to tell if they came from a man or a woman.)

On the other hand, the X and the Y chromosomes are an unusual pair. Since only men have the Y chromosome, there cannot be any genes absolutely necessary for survival on it. The Y is a tiny, stubby little thing—it only makes up about 0.38% of the total DNA in a (male) human cell. In other words, even if it had nothing in common with the X chromosome, there would still be very little difference between male and female DNA.

As it turns out, the Y actually contains a handful of genes that are duplicated from the X, so the genetic difference between men and women is even smaller than you might expect. (The remaining genes are mostly involved in driving the assembly of the male reproductive apparatus.) Now, because the X is quite a bit bigger than the Y, women have more total DNA per cell than men (about 2% extra), even though that DNA is in an extra, redundant X chromosome. So I guess the answer to your question depends on how you want to measure that difference. TenOfAllTrades(talk) 02:17, 5 December 2006 (UTC)

Thank you for the prompt replies!!! 74.96.217.202 05:53, 5 December 2006 (UTC)

However, there may also be genes in other chromosomes which are male or female-specific, being triggered by some protein produced by the Y chromosome that says "I am male", or the lack of such a protein, meaning "I am female". If we convert the genetic code into computer code (and have a bit of fun in the process), it might look like this:

IF (MALE) THEN
  MOVIE_PREFERENCE = "Car chases and big explosions"
ELSEIF (FEMALE) THEN
  MOVIE_PREFERENCE = "Whining about relationships for two hours"
END

StuRat 08:34, 5 December 2006 (UTC)

Note that even though females have two X chromosomes, one is inactivated in most cells. Take a look at X-inactivation and perhaps also Tortoiseshell cat for a striking visual example of this Nil Einne 17:24, 5 December 2006 (UTC)

Also, nit-pick: Sex is not always clearly defined by whether or not you have a Y chromosome. There are numerous articles here on Misplaced Pages that describe conditions where a person can have an XY pattern and still be female, or where a person can have patterns of XXX, XXY, et cetera. Obviously the 'rules' may vary. ~ lav-chan @ 18:33, 10 December 2006 (UTC)

Red blood cells

Do red blood cells have organelles? If so what are they?

Read about red blood cells. They do have organelles, but mammalian red blood cells don't have nuclei. bibliomaniac15 02:40, 5 December 2006 (UTC)

Er, a minor quibble—as far as I know, mammalian erythrocytes lack an endoplasmic reticulum and mitochondria, as well as a nucleus. Do you know of any organelles that are retained? TenOfAllTrades(talk) 02:46, 5 December 2006 (UTC)

As far as I know, and supported by the red blood cells article, all organelles are lost. Of course, we're only talking about mammalian and mature cells here Nil Einne 18:34, 5 December 2006 (UTC)

Number of sexes

Would it be possible for some hypothetical organism to have more than two biological sexes? If not, why not? I'm pretty sure I read somewhere that a third sex would be strongly selected against, though I can't remember why and might just be pulling this out of my ass. I checked sex, evolution of sex, and sexual reproduction, but it was nothing doing. 24.11.177.133 02:57, 5 December 2006 (UTC)

Interesting question. Nature generally likes doing things in pairs, it provides redundancy without over compensating, it provides balance and symmetry, there are many reasons to do things in twos. Most animals have two sexes because it mixes the gene pool, we tend to be attracted to people who's genes compliment our own. Finding a partner to reproduce with is a biologically demanding activity. For most entities (including most humans) it takes up a majority of their effort. It would be beneficial NOT to have to find a partner to reproduce, but obviously mixing the gene pool is a BIGGER benefit. Having to find a third partner compatible with you and the second would add a magnitude of complexity, for that reason I don't think it's really a possibility. But I guess I haven't really disproved that it CAN'T happen and therefore I haven't given much evidence why it has never been witnessed even is some strange plant somewhere or something, I suspect there might be a more fundamental reason…Vespine 04:02, 5 December 2006 (UTC)

Would there be then a three-fold cost of sex for organisms with three sexes (for example)? If so, is this just too high a cost then for the organism to be recompensed by the advantage conferred by the creation of genetic variation (which I think is basically what Vespine is saying)? 24.11.177.133 05:37, 5 December 2006 (UTC)

The primary benefit of sexual reproduction is that it gives a chance to recombine genes, which greatly increases the rate at which advantageous mutations can be separated from harmful ones. Having three (or more) genders doesn't really provide a lot of extra benefit, but it sure would make it harder to find compatible mates. --Dgies 06:24, 5 December 2006 (UTC)

Sure. Why not? For a fictional account of such a situation, see The Gods Themselves by Isaac Asimov. B00P 07:57, 5 December 2006 (UTC)

I've read The Gods Themselves. What I'm wondering is if such a situation could only occur in a fictional account, as it were. I haven't really gotten a straight answer yet. --24.11.177.133 12:10, 5 December 2006 (UTC)

There are shrimp that have two different kinds of females. Then there are ants that have two different types of males. For both, reproduction requires only one or two individuals. But for the ants the colony as a whole requires three sexes to survive. (Just googling for three sexes...) Weregerbil 13:44, 5 December 2006 (UTC)

A Star Trek Voyager episode had something where there were 3 sexes, and the third was heavily discriminated against. Crisco 1492 07:06, 6 December 2006 (UTC)

Some real organisms do have a multitude of sexes. This is described in some detail in the book The Mathematics Of Sex, which I've just read. I forget the author - Clio somebody I think. Its a slim popular paperback so you don't have to have any maths skills to read it. As far as I recall they were things like slime moulds and fungi. I think she also implies that a third sex might be evolving in humans. 81.104.12.52 20:28, 6 December 2006 (UTC)

blizzard of 1993

What was it like during the blizzard of 1993 for htose who were there and will this likely occur again in the next fifty years since the environment is fragile right now. Dragonfire 734 02:59, 5 December 2006 (UTC)

Why is the environment fragile right now? There are blizzards and record cold every year. There has been no significant difference in the amount of intensity of storms over the past 100 years. --Tbeatty 04:56, 5 December 2006 (UTC)

So is global warming "bad science?" What effect would actual global warming have on storm intensity? Edison 15:42, 5 December 2006 (UTC)

Mosquitos - How they benefit humans and the environment

Do they? Or are they completely vile creatures that can only improve the world by their extinction?

They don't benefit humans at all; they only annoy us and help spread disease. However, animals like frogs may depend on mosquitoes as their main diet. --Bowlhover 04:04, 5 December 2006 (UTC)

They don't benefit humans directly, but they are the primary source of food for a huge number of other animals, including many species of birds, amphibians, other insects, etc. Anchoress 04:07, 5 December 2006 (UTC)

But birds can eat a lot of other insects, no? Would they really become extinct if mosquitoes were gone? --Bowlhover 04:18, 5 December 2006 (UTC)

I don't know, but I didn't say they would. Just read my post, I didn't mention extinction either way. Anchoress 04:20, 5 December 2006 (UTC)

Sorry for the mistake then; I meant to say "would their numbers really dwindle by any significant amount?" If not, how do mosquitoes indirectly help humans? --Bowlhover 04:29, 5 December 2006 (UTC)

Well, banning DDT allowed the mosquito population to flourish which greatly reduced the poverty rate in sub-saharan africa by killing millions of the poorest people on earth. Then by banning cheap refrigerants, millions more starved to death. The Kyoto treaty should wipe out poverty as we know it. --Tbeatty 05:01, 5 December 2006 (UTC)

Those are some pretty bold assertions. Care to provide a reputable reference for them? --Dgies 06:26, 5 December 2006 (UTC)

Hereis the DDT one. The Freon reference is Scientific American in 1997 as well as other places. It's also a simple logical conclusion. --Tbeatty 14:45, 5 December 2006 (UTC)

Be careful with the DDT-is-good story. It seems to originate from industry-backed thinktanks - More: gmwatch Arakrys 02:28, 28 December 2006 (UTC)

Controlling our population? That's about all I can think of. | AndonicO 16:35, 5 December 2006 (UTC)

Indirectly, I would argue mosquitos have had an effect on scientific research and also human development (as with other problems, many populations/countries have had to develop ways to deal with the problem). Whether this has been good for us or not is up for debate. In terms of the environment, I would argue anything that kills humans is good for the enviroment Nil Einne 17:18, 5 December 2006 (UTC)

That's why your argument is so silly. --Tbeatty 04:15, 6 December 2006 (UTC)

A gamma ray burst from a relatively nearby star would kill all humans. I fail to see how it would do the environment any good though. GeeJo ⁄_(c) • 01:05, 6 December 2006 (UTC)

Unit

Is there a name for the unit kg times m/s ? Deltacom1515 04:11, 5 December 2006 (UTC)

Whoops, found it, looked at this table incorrectly. Sorry. Deltacom1515 04:21, 5 December 2006 (UTC)

(In either case, it should be Newton-second). --Wirbelwindヴィルヴェルヴィント (talk) 04:22, 5 December 2006 (UTC)

scientific termn for...

parents? is there any?. :|. --Cosmic girl 04:34, 5 December 2006 (UTC)

Well progenitor, which is my answer, redirects to ancestor. Anchoress 04:46, 5 December 2006 (UTC)

It's "parents." B00P 08:00, 5 December 2006 (UTC)

any other than progenitors or @$$holes? (sorry)... any other than progenitors?...--Cosmic girl 15:25, 5 December 2006 (UTC)

My my it sounds like you have issues, but I guess you are a young adult... :-P Anyway I don't think there is any other commonly used term other then parent or progenitor. Note that parent is used in various context in biology, for example parent cell or parent plants (not parents). You also have a daughter cell (but no son cell). Even in spermatogenesis. Nil Einne 16:47, 5 December 2006 (UTC)

aww 2 bad... haha.thank u anyways , sorry for the random question.--Cosmic girl 00:31, 6 December 2006 (UTC)

Helium

I know the question how many bolloons would it take to lift me up has probabely been asked a million times but I need to know how to calculate how much helium it would take to lift a given weight like one pound?67.125.159.101 04:55, 5 December 2006 (UTC)

According to lighter than air, helium and hydrogen both have about 1 kilogram of lift per cubic meter of gas at room temperature and sea level pressure. --Wirbelwindヴィルヴェルヴィント (talk) 05:16, 5 December 2006 (UTC)

Just for fun, see also cluster ballooning and "Carried Away".--Shantavira 09:07, 5 December 2006 (UTC)

Thank you that was extremly Helpful.

SOCIAL SCIENCE

Hello, I would like to know if social psychology can or cannot explain all social problems.

That's a big question. I would say that, no, they can't, in that social problems can't be reliably predicted using existing models of social behavior, which often conflict with each other. StuRat 08:15, 5 December 2006 (UTC)

That's easy. Social psychology cannot explain ALL social problems. 220.239.110.225 09:50, 5 December 2006 (UTC)

IMHO it depends if you're talking theory here or practice. In practice, social psychology cannot and is unlikely to ever be able to explain all social problems. However in theory, social pscyhology can explain all problems. However this would also apply to virtually every area we study so I guess it doesn't really say much. Of course, I'm agnostic and don't believe 'God' has any relevance to us Nil Einne 16:38, 5 December 2006 (UTC)

Just noticed this question had already been asked above and appears to be a homework question Nil Einne 16:54, 5 December 2006 (UTC)

Normal flora

Why is it that the immune system does not attck normal flora? Thanks.

Those are normally outside the body, so not subject to the human immune system. Although counterintuitive, the contents of the digestive tract are considered to be outside the body, since they must traverse the intestinal walls to enter the body. StuRat 08:12, 5 December 2006 (UTC)

The gut contains numerous M cells that take antigens in the gut lumen and present present them to lymphocytes of the gut-associated lymphoid tissue, overcoming that problem. A number of commensal bacterial species are pathogenic and can result in opportunistic infections in immunocompromised individuals. The actions of the M cells to constantly sample the luminal antigens, present them to GALT lymphocytes, and elicit antibody secretion, keeps these pathogenic species at bay. --David Iberri (talk) 12:08, 5 December 2006 (UTC)

Some diseases may involve immune system response to the normal flora, for example: evidence continues to mount that the indigenous commensal flora of the gut is the target of the immune response in IBD. --JWSchmidt 14:51, 5 December 2006 (UTC)

Cracking Achilles

Sometimes when I get out of bed I have a bit of tension in my ankles. My Achilles tendon basically just feels a little tight. If I squat down just a couple inches by bending my ankles and knees, I'll hear and feel a pretty loud crack. Like cracking my knuckles but louder. The cracking sensation comes from the area of my tendon though I'd expect it to come from the joint. Why is it that I feel it in the tendon and what is it that's cracking? Dismas| 08:10, 5 December 2006 (UTC)

Not sure, but I suggest you stretch very slowly, to avoid a potentially serious injury. StuRat 08:18, 5 December 2006 (UTC)

Might it be a similar phenomenon as when you 'crack' your hands by interlocking fingers then bending with plams outward?--Light current 08:23, 5 December 2006 (UTC)

Like I said above, "Like cracking my knuckles..." Is this an American expression that maybe I should have explained? Light, you and I are talking about the same thing. Although with my ankles it doesn't feel like it's coming from the joint whereas it does if you crack the knuckles of your hands. Dismas| 08:46, 5 December 2006 (UTC)

No its not the joints in your hands either its the tendons stretching/moving/sticking in their 'tunnels'. Just had one then in my thumb. Not the joint!--Light current 14:18, 5 December 2006 (UTC)

Ah, I thought it had to do with the joints. So we were talking about the same thing, I just had the wrong part popping!  :-) Thanks, Dismas| 14:35, 5 December 2006 (UTC)

The mechanism is the same as in Cracking joints, and likely to be harmless. In my own case it is not the Achilles tendon, but rather the tendons from the lower leg to the side of the foot, running over the side of the ankle, that cause a crack when they jump from the front to the back of the lateral malleolus. If you feel carefully, it is often possible to locate the place where the sound is generated - but remember that a "repeat pop" is usually not possible for quite a while, so you have to place your finger before moving the joint. -- Seejyb 15:29, 5 December 2006 (UTC)

Mushrooms

what is the nutrient quality of mushrooms? how much protein, carbohydrate and fat is in a mushroom? The King of Spain's beard 09:58, 5 December 2006 (UTC)

See here: . StuRat 10:26, 5 December 2006 (UTC)

Perhaps the best nutritional value of mushrooms is if they replace less healthy foods in your diet. For example, a portobello mushroom "steak" is far healthier than a beef steak. StuRat 10:29, 5 December 2006 (UTC)

• Remember, there are numerous types of mushrooms. Each will have their own nutritional values. - Mgm| 11:06, 5 December 2006 (UTC)
  • Including some with some rather nasty toxins which will kill your liver Nil Einne 16:32, 5 December 2006 (UTC)

For all these nutritional questions one can go to the What's in the Foods You Eat - Search Tool page of the US Dept of Agriculture site, enter "mushrooms" (or whatever food you wish to find data for) in the search box, select the type/method of preparation and the mass/volume, and you will be presented with a very detailed analysis of what the food contains. I suspect Stu's site uses the USDA data (which is of course not copyrighted, so Wikipedians may find the tables useful). Stephanie Ingram's article is a classic reference, but the figures are not tabulated, nor so detailed. -- Seejyb 15:57, 5 December 2006 (UTC)

taking growth hormone, side effects?

Hi all

can someone please tell me whether taking growth hormone has any detrimental effects. i mean taking it as an adult as a means for incresed muscle mass

I know taking anabolic steroids has a definite detrimental effects after one stops taking, like less testosterone , reduced gonad size,increased risk of cancer, etc, but what are the side effects of taking HGH?

thanks

Nixon Chan

See Growth hormone#Risks and side effects of GH treatment. –mysid☎ 12:04, 5 December 2006 (UTC)

Moon

Is the moon in the sky just as often in the daytime as it is at night? TimBuck2 12:24, 5 December 2006 (UTC)

Yes, because the Earth rotates. See moon for more details.--Shantavira 13:44, 5 December 2006 (UTC)

The trick, of course, is that when the moon is full (away from the sun), it can only be seen in the night sky and when it's new (near the sun), it can only be seen in the daylight sky but, but without reflected light, only becomes apparent during solar eclipses. But between the instants of being absolutely full and absolutely new, the moon can be seen in the daytime sky during at least that portion of the day between moonrise and moonset.

Atlant 17:27, 5 December 2006 (UTC)

Your question is silly. Are you talking about a 24 hour period? In which case, a simple demostration would prove your assertion wrong. In Antarctica during summer, daytime is 24 hours and nightime is 0 hours. Therefore the moon in the sky more often in daytime than nighttime. QED. 202.168.50.40 22:40, 5 December 2006 (UTC)

No, the question may be "elementary," but it is not "silly." It was a simple Yes/No query answered by Shantavira. Done. B00P 23:24, 5 December 2006 (UTC)

I think most people understand that if you say daytime without specifying anomalies like Antarctica during summer which maybe 0.00000001% of the population have ever experienced, daytime means AVERAGE daytime. ;) To which the answer is YES. Vespine 00:24, 6 December 2006 (UTC)

more than 0.00000001% of the population have experienced Antarctica during summer. (If you assume 6 billion people, your number comes down to less than one individual) :) Lukas 00:35, 6 December 2006 (UTC)

I wouldn't be at all surprised if the sun's gravitational field perturbed the moon so that it spends slightly different amounts of time directly above the day and night sides of the earth. And 202.168.50.40 has a point: to answer the question we need some kind of average. We can't average over any given day. But what is "average daytime"? We can't average over any given year either, since the solar and lunar cycles aren't commensurate. And you can't average over all time, since the orbit of everything is constantly changing.

So I think a more precise answer than "yes" would have to be "it almost is, if you average over all possible positions of the moon and sun but fix everything else, which doesn't quite physically happen, although it almost does". Melchoir 01:02, 6 December 2006 (UTC)

You're making it overly complex. A simple question deserves a simple answer. StuRat 01:49, 6 December 2006 (UTC)

Is it really a simple question, though? If I'm asked if the moon is really usually out at night, as it may appear, then the answer is just no. But if I'm asked if the moon is out equally often at night or at day... well, is it? Ideally one would spend the time to quantify the asymmetries to get a feel for how insignificat they are, but that would take a lot of effort. Melchoir 04:06, 6 December 2006 (UTC)

Unless they indicate they need that level of precision, an approximate answer will do. For example, in problems dealing with train speeds, distances, and time elapsed, we can assume we will ignore the answer being different depending on the frame of reference, due to relativity, unless they specifically ask for us to discuss such effects. Newtonian physics would be entirely adequate for such an answer, by default. StuRat 13:12, 6 December 2006 (UTC)

Well, okay, but trains mostly appear in toy problems. They're kind of like boy-or-girl questions in elementary probability: you're expected to assume the base probability is 50-50, and if I objected that it's slightly different, that would just make me a wiseass. But here the question isn't about figuring out the mathematical consequences of some commonly assumed symmetry: it's about whether or not that symmetry physically exists in the first place. If someone asks "are boys just as common as girls?" then it's perfectly appropriate to talk about the genetic and social factors that skew the result. Melchoir 18:53, 6 December 2006 (UTC)

Note that the reason it doesn't seem like the Moon is up as often in the day is that it's often hard to see, being much less bright than the Sun. This is particularly true on a cloudy day, where it can be impossible to spot the Moon during the day, while the moonlight visibly lights up the clouds at night. StuRat 01:49, 6 December 2006 (UTC)

Weakness and Numbness to the Leg

Recently, my leg would turn weak and numb all of a sudden while running. This happened before, but it went away after a while. Should I go see a doctor? By the way, my leg is not swollen.BlueLighter 14:22, 5 December 2006 (UTC)

Always wise to see a Doc, just in csae 8-)--Light current 14:42, 5 December 2006 (UTC)

Sounds like Sciatica, but you should see a doctor. From personal experience, this is something that is difficult to get a handle on, and has as much chance to go away by itself, as doing a massive therapy program. At the very least, you should see a physiotherapist, and do the recommended stretching. --Zeizmic 16:14, 5 December 2006 (UTC)

If only so that you can rule out such serious possibilities as Deep vein thrombosis, you should definitely see a real doctor, not a Wikipedian.

Atlant 17:29, 5 December 2006 (UTC)

Turns out, it was just some repetitive position for too long, aka. sitting in a bad position... so i'll live :DBlueLighter 09:45, 7 December 2006 (UTC)

What is science?

I looked at the Science article. It gives a purely tautological, hollow description. Does anybody know what Science really is, or really is about?

The only thing I am sure of is that a scientist is someone who is paid for their work.

If this is regarded as a troll, please delete it immediately. Theavatar3 17:59, 5 December 2006 (UTC)

To quote the first sentence: "Science in the broadest sense refers to any system of objective knowledge." Seems pretty straightforward to me. DMacks 18:07, 5 December 2006 (UTC)

Science is (among other things) a set of methods. Maybe Scientific method would help explain? Friday (talk) 18:11, 5 December 2006 (UTC)

Ah yes, the second sentence of the article. Theavatar3, what in particular actually confused you when you read that first paragraph? DMacks 18:14, 5 December 2006 (UTC)

If I had to take issue with only one word, it would be 'objective'. I personally feel like the very word 'objective' is objectively useless.

Objective is necessary here - the alternative is subjective knowledge - see my comment below about marbles; the colour of the marbles is objective knowledge, my favourite marble ie the BEST one is subjective knowledfe - science doesn't do subjective I think..87.102.32.250 20:36, 5 December 2006 (UTC)

One might be tempted to read that as a suggestion that science itself is useless. It is manifestly not at all useless! Refrigeration is truly a wonderful thing, and a product of science.

Perhaps what I am getting at, is that science is the new religion. You cannot blaspheme against it. Or maybe I just did. Enough said. :) Theavatar3 18:26, 5 December 2006 (UTC)

You can 'blaspheme' science (whatever that means). However as with any argument, you have to have a reasoned argument otherwise people will just point out the flaws in your argument and say your stupid. The difference with religion is that with religion, your can't really argue with it because it's based on belief. While many religioi people try to use emperical logic, ultimately,they all rely on belief since that's the basis of religion. Nil Einne 18:43, 5 December 2006 (UTC)

Comment - if you've ever been in the situation to notice that a 'scientific fact' - eg printed info. is wrong or suspect and try to raise the issue you would know why some people describe science as the new religion - and what it's like to be a 'scientific heretic'. Despite that science is supposed to be provable - try to point out an error in the body of collective scientific knowledge and be greater with inertia/blank stares/people questioning your authority etc.

If you can come up with (objective) evidence that a scientific fact is wrong and the evidence provided can be independently reproduced by others then at the very least, even your enemies would have to conclude that There is reason to suspect that the scientific fact is wrong. 202.168.50.40 22:31, 5 December 2006 (UTC)

Perhaps you'd be interested in studying the Philosophy of science DMacks

My view is that there is a fundamental difference between science and religion - in that scientific theories are evidence based; the currently accepted explanations - the scientific facts - are observed to fit the evidence in repeatable experiments. That does not mean, necessarily, that the explanations are always correct - just that they do fit the evidence - and that, if you have the necessary equipment, and method to follow, that you'd be able to reproduce the results in your own experiment. Now it may be that new observations come in which call into question the accepted explanation - but that's fine, since this is science and a new theory might be needed to explain the discrepancy. As long as these new observations are repeatable in experimentation (by anyone with the right equipment), then you'll not be branded a heretic in serious scientific circles by raising it. In religious views, as far as I can see, the accepted explanations seemingly cannot be called into question and seem to be based on little evidence other than centuries old manuscripts.Richard B 13:04, 8 December 2006 (UTC)

the description is a bit hollow - if I classify my collection of marble base purely on measurable quantities - size,colour,material,surface,opacity - is that a science of marbles - seems so.87.102.32.250 18:37, 5 December 2006 (UTC)

Yup. DMacks 20:25, 5 December 2006 (UTC)

Just checking. I think the first paragraph of science is an excellent description of it.

The only thing I am sure of is that a scientist is someone who is paid for their work.

Wrong. Wrong. Wrong. A scientist may be paid for his/her (scientific) work. But someone who is NOT paid for their scientific work can still be a scientist. 202.168.50.40

If two wrongs fail to make a right, how about three wrongs? Theavatar3 00:10, 7 December 2006 (UTC)

Yeah. They're often called "grad students" :) DMacks 22:48, 5 December 2006 (UTC)

A scientist is any entity(or human) who (genuinely) attempts to add to the known scientific body of knowledge by utilizing the scientific method. An entity who does this successfully is known as a successful scientist. 202.168.50.40 22:55, 5 December 2006 (UTC)

"Scientists use The Scientific Method" does not work, since no single scientific method exists. In fact, if we could define which methods were scientific, then we would have also defined what "science" actually is.--Wjbeaty 01:45, 6 December 2006 (UTC)

Defining what is "science" and what is not "science" in a rigorous fashion is quite difficult. See demarcation problem for some discussion of the difficulties involved. Broadly speaking what we mean by science today is a community of systematized research guided loosely by philosophies of rationalism and empiricism. That's not a precise answer, though, and doesn't cover a lot of fields that we would normally consider to be "science", and it would include a lot of things that we might be skeptical of calling "science". But it has been known for a very long time that there is no single scientific method, no single scientific approach to a problem, and no historical definition of science which applies equally well across time. Science in the early 21st century is quite a different thing than even the early 20th century, though the primary aspects of what we'd today recognize as science became solidified in the late 19th century. There is little distinction between what we'd call "science" today and the more generic category "natural philosophy" or "natural knowledge" in the periods before that. In non-European cultures the distinction does not come about primarily until after contact with Europeans. --24.147.86.187 00:59, 6 December 2006 (UTC)

As an aside, one should be as cautious in asking scientists what "science" is as one would be in asking a priest what "religion" is. There are entire academic disciplines which look at science in ways different than the scientist normally would (history of science and technology, history and philosophy of science, philosophy of science, anthropology of science, sociology of science) and they are good to consult if you are looking to get around some of the very generic idealisms that scientists employ in discussing their field in broad terms. Not meaning this to disparage anyone, of course, but natural scientists are experts on nature, not science itself. --24.147.86.187 01:04, 6 December 2006 (UTC)

Part of the reason this (and other similar querstions) are hard to answer is that they include a subtle logical loop, like this:

Consider a concrete object ("chair") and the symbol attached to that object (the word "c-h-a-i-r" in English, or "c-h-a-i-s-e" in French or whatever). We have consensus over the object "chair", because we can all point to it, locate it, and broadly agree it exists as we understand "existance". But words like "science" do not have any existance independent of the fact we define them based upon other words. There is no object we can all point to and agree is "science". Its a notion, a symbol, a token; it signifies what we define it to signify when we create the language that includes the token "s-c-i-e-n-c-e" as a valid token.

So the problem we have is, science means in a sense, precisely what we define it to mean. it doesn't have objective existance beyond that. It is a symbol, used to define a methodology or approach, and as we define it, that is what it is. The problem is that like other notional words ("love", "god", "free-will") we each think we use the word the same way but we in fact probably do not, we do not have one definition but a myriad of broadly agreeing definitions.

So the real answer is this: There are approaches of studying the world and what we find in it, that attempt to exclude that which cannot be obeserved or tested independently, which require evidence that can be replicated, that looks for patterns and rules. And by and large such methodologies work in this world, and many people follow variations on that theme in exploring the world, whatever term they use. But when you ask "what is science", you yourself define the word "science". As you define it, thats what it means.

Hope that makes sense! FT2 05:34, 9 December 2006 (UTC)

Auto Rickshaw

Are there any Auto Rickshaw (Tuk-tuk) dealers in the continental United States?70.239.214.42 18:05, 5 December 2006 (UTC)

Isn't that about the same thing as a golf cart ? One major diff is that a golf cart has four wheels, which I believe is required for stability. Also, golf carts are electric, and generally only have two seats, but you could probably find a four seat version somewhere. StuRat 18:16, 5 December 2006 (UTC)

From a quick Google and Nil Einne 18:29, 5 December 2006 (UTC)

predominant power source

Isn't it just like the Federal government to travel all the way to the moon to establish solar power as the predominant power source when there is no air or water there to breath, drink or pollute instead of making it a priority to establish solar power as the predominant power source here on Earth first? 71.100.6.152 18:19, 5 December 2006 (UTC)

There is no wind, fossil fuels, wood, hydroelectric, or geothermal (lunathermal ?) power on the moon, so that pretty much leaves just solar power or possibly nuclear, if you bring the fuel yourself. StuRat 18:24, 5 December 2006 (UTC)

A better answer would reference Colonization of the Moon#Energy, and remind the questioner that it is not appropriate to call for speculation on the reference desk, as I just did. RDWarrior 18:34, 5 December 2006 (UTC)

While that link is useful, it doesn't address the question directly, which is why different energy methods are preferred on the Moon. The primary reason is that many terrestrial energy sources are absent on the Moon, which I addressed with my answer. StuRat 01:13, 6 December 2006 (UTC)

Also it has been pretty much proven that grid powered from solar panels actually can't be made without fossil fuels. This is because the amount of engergy a panel produces in its lifetime does not match the amount of energy needed to make the panel and make a energy container such that power can be supplied at night. They are only made today because cheap and easy fossil fuel. In other words, like using Ethenol in fuel, it is only helpful to a certain degree but is ultimately not a solution for global replacement of all coal power. The power source on the moon has nothing to do with establishing a new power source. Solar power is just the cheapest way to get power on the moon since otherwise you would have to bring all the fuel with you. The point of the moon base isn't to use solar power, its to do many other experiments etc and hopefully perhaps it can lead to new ways to make better solar panels because at the moment the ones we have are not close enough to being realistically possible to power a grid without nuclear/coal power.

I know about the energy in /energy out equations, but whither the "can't be made without fossil fuels"? Do we have a reference for that? -- Seejyb 05:39, 6 December 2006 (UTC)

Certainly nuclear power or some other source of energy could be used, but perhaps, if made of plastics, some petroleum is needed to build solar cells. Also note that the "it takes more than X units of energy to produce a solar cell capable of producing X units of energy" argument also applies to fossil fuels. That is, to produce X units of energy, you use up X units (by burning the fuel) and also some extra for the extraction, refining, and delivery of the petroleum. I suspect that, once the "energy lost" by burning the fossil fuels is factored in, solar cells have the potential to use far less petroleum than burning petroleum does, especially if they were mass produced on the same scale. StuRat 13:06, 6 December 2006 (UTC)

Also is this fossil fuel to make solar energy relation consistent for non voltaic panels such as thermal concentrators? 71.100.6.152 07:03, 6 December 2006 (UTC)

I believe that passive solar energy, like heating your house with sunlight, is far more economically viable than active solar energy, where you create electricity. However, the application of passive solar energy is limited mainly to heating things. You can't easily run a radio with it, for example. (I suppose you could heat water in a steam engine, generate electricity with a dynamo driven by the steam engine, then run the radio off this electricity, but such a process would be even less efficient than generating electricity from solar cells.) So, it would make sense for the moon base to be heated with passive solar energy (point a few large mirrors at the base, painted black, for example) and then use solar cells to produce the electricity needed. StuRat 12:29, 9 December 2006 (UTC)

Carbon Dioxide Tax

Is it a good idea for the government to introduce a tax on carbon dioxide emissions for places like factories that are producing excessive amounts? If so could they do this by putting carbon dioxide meters inside the factories and if too much carbon is produced, the factory pays a certain amount of tax dependent on how much excessive carbon was produced? thanksHerbynator 18:57, 5 December 2006 (UTC)

Sounds good, except for who has to decide what "excessive" means. I'd just charge a constant rate for each kg of emissions. Those plants that pollute less would pay less. Use the proceeds to finance alternative energy programs. Gradually increase the tax until the most polluting plants are forced to clean up or close. StuRat 18:27, 5 December 2006 (UTC)

A better answer to this question would reference Pigovian tax, as I just did. RDWarrior 18:32, 5 December 2006 (UTC)

That article is somewhat relevant, but it's not specifically about carbon dioxide emissions, and doesn't address the tax being on all emissions versus only "excessive" emissions. Had they asked about the general practice of using a tax to change behavior, then that would be more relevant. StuRat 00:56, 6 December 2006 (UTC)

Any taxation with technology has to be reliable, accurate, cheap to maintain (ideally cheap to install) and a period of time to allow for pre-tax law changes would only be fair. If you have a firm that goes from previously paying nothing for it's output to £3m a year then this could make a major change in profitability, thus any new tax-policy has to look at the effect it would have on companies/workers/the country's economy as a whole. It is somewhat worthless reducing CO2 if the nation survives doubly impoverished, the battle is in reducing CO2 whilst maintaining the living standards we have today. ny156uk 18:42, 5 December 2006 (UTC)

I don't think it's possible to have a tax that's high enough to change behavior but not high enough to "cause pain" as it's that "pain" (loss of profitability) which actually motivates change. If the tax is less than the substantial cost to reduce emissions, the plants will have no economic incentive to clean up their act. StuRat 00:51, 6 December 2006 (UTC)

Thanks guysHerbynator 18:56, 5 December 2006 (UTC)

No. Breathing produces too much CO2 to tax reasonably. --Tbeatty 04:11, 6 December 2006 (UTC)

• Breathing is something we can't stop doing without dying, so it shouldn't be taxed, but we do have the Kyoto protocol to decide the meaning of excessive. Unfortunately, the biggest polluter of all (United States) didn't sign that agreement. - Mgm| 10:36, 6 December 2006 (UTC)
  • The Kyoto Protocol is simply a wealth redistribution scheme, not a serious environmental improvement treaty. Kyoto does nothing to define excessive as it exempts certain countries. What it does do is create a non-existent commodity that otherwise poor nations will just magically obtain: carbon credits. It gives them an exportable commodity that they can sell. You may think this is good, but it shouldn't be hidden in a veil of "helping the environment".

Nurses uniforms

While watching scrubs.. I realised that the nurses wear different uniforms. For example, Carla wears red, pink, purple etc coloured scrubs whereas Laverne wears multicoloured blouses, as do some other background nurses. Does that stand for anything or is it a matter of preference?

A good description of scrub coloration can be found at Scrubs (clothing)#Modern scrubs. RDWarrior 18:53, 5 December 2006 (UTC)

It depends on the facility. Sometimes people who work in certain areas wear certain colors and at other facilities there is more freedom or complete freedom. For instance, lots of pedes nurses wear patterned scrubs with cartoon characters. Since the Korean War, green scrubs are worn in O.R. because blood looks not so red against it as it does on white. -THB 20:16, 5 December 2006 (UTC)

Thank you for the replies. In Scrubs though, waht Laverne and some of the other nurses wear aren't exactly scrubs. They wear trousers with some kind of almost floral blouse. Could it be used to show the difference between the types of nurses? I am not familiar with American Nursing systems, but using British nursing - Carla could be the equivilant of a matron and a sister etc? I don`t meant to be trite here, but, whether or not "Scrubs" complies with normal convention or not, you have to remember that this is, after all, TV. Maybe many/most/all of their choices are simply to make color-TV a bit more interesting! Just could be. Dave172.135.3.189 00:01, 6 December 2006 (UTC)

Oops! I think I did a booboo up above. My sincerest apologies to whomever I might have 'deleted'. I`m still a neophyte here. I hope someone can 'fix' my mistake. Sorry again! Dave172.135.3.189 01:50, 6 December 2006 (UTC)

One issue with scrubs is that they need to be washed rather thoroughly to sterilize them. They used to be all white, as chlorine bleach was used which would fade any colors, anyway. With the use of non-chlorine bleach, whites are no longer necessary. However, some color transfer is still possible from a hot water washing using non-chlorine bleach, so it's a good idea to have them all be the same solid pastel color, to minimize this effect. StuRat 00:41, 6 December 2006 (UTC)

Every hospital tends to have its own uniform dress code for nurses, with some exceptions as mentioned above, e.g. Paediatrics. In the theatres where I work everybody wears blues and the hat colours are used to tell people apart, e.g. blue for medical/trained theatre staff; white for students/untrained staff; green for visitors/patients. From memory, one of the "Scrubs" DVD collections (?Series 2) actually has ?the director talking about the choices for the different colours of scrubs.Mmoneypenny 21:45, 6 December 2006 (UTC)

Green Hand-Drying

In the toilet of the pub I was in yesterday (yes, I am a Brit), there was two methods of hand drying equipment, disposable paper towels and a mains powered hot air machine. Which is likely to cause least environmental damage? The towels appear to be recycled. Cheers, Situationist 20:46, 5 December 2006 (UTC)

The hand-drier would have the smallest 'environmental' impact because once installed it requires purely electricity and maintenance to run. The paper-towels will need to be made, delivered, collected (used), recycled, made, delivered, collected and so on. So in the long run the energy costs of a hand-drier are cheaper than all that transport/movement of goods to and from the toilets of our great land.

Personally I prefer paper to hand-driers because you have to stand at a hand-drier for quite some time to get any worth from the experience and, well, many of the public toilets i've had the misfortune to need to visit are not what I would call environmentally pleasing to behold. ny156uk 21:46, 5 December 2006 (UTC)

What about the towel machines that actually dispense and collect a reusable cloth roll for drying purposes? Assuming they are dispatched, collected, and cleaned in great quantity, they should be even more eco-friendly than either of the others. Of course ALL this is speculation since we don't have real figures to work with. --Jmeden2000 22:31, 5 December 2006 (UTC)

Don't know the actual figures but the ones here in NZ are touted as an eco-option. Also, I would say they are the most commonly available hand drying method in NZ (don't know about pubs specifically tho). Personally, I prefer the cloth roll drying thing, followed by paper towels. I don't really like the blow drying equipement because I like to wet my face and using my hands to dry my face doesn't work very well Nil Einne 11:03, 6 December 2006 (UTC)

I don't like the hand drying machines for two reasons:

1) They often seem to have been mounted by dwarves, forcing me to bend over and hurt my back to use them. The sinks also were mounted by dwarves, but I don't have to bend over them for several minutes, at least.

2) I need a piece of paper towel to open the bathroom door...there's no way I'm going to touch that door handle directly. If need be, I will go and grab some TP to use (as a "fecal matter shield") when touching the handle.

As for the cost of hand dryers, note that it's more than twice as high in summer, as the heat generated puts an additional load on the A/C. Thus, one kilowatt hour of hand dryer machine operation requires a bit more than one kilowatt hour of A/C (due to the lower efficiency of A/C). In the winter, the hand drying machine actually reduces the load on the furnace slightly. 00:03, 6 December 2006 (UTC)

This is (fortunately) not at all true! Air conditioning actually has an coefficient of performance greater than 1; in the US, new residential units have to have an efficiency of approximately 324%, and 224% is already commonplace (this from the SEER article). This means that the economic penalty of venting heat inside an air conditioned area is something like ${\displaystyle 1+{\frac {1}{300\%}}={\frac {4}{3}}}$, which is not so bad. And in the winter, I personally calculated one year that it cost me twice as much to heat with electricity (possibly in the form of, say, a computer) as with the natural gas the dedicated heater used; therefore electricity then is effectively half-price because it will save an amount of heating that would have cost half as much as the spent electricity. Of course, there are ways not to get this, like having an incandescent lamp so close to a window or vent that it dumps a noticable amount of its energy directly to the outside without heating the room, or (for the air conditioner) putting a heat source next to its thermostat so that it runs unnecessarily (and thus increases the rate of heat input through the walls). On the whole, however, the story of the interaction between HVAC and electric appliances is a happy one; 1/2 and 4/3 certainly don't average to even 1! --Tardis 16:52, 6 December 2006 (UTC)

I'm missing the units so there's no way i can check your figures. Besides, making electricity is not 100% energy efficient so you should add the loss of energy during production and transporting. Arakrys 02:32, 28 December 2006 (UTC)

A further possible issue is that if you're going to air-dry your hands, you need to wash more to get the same level of cleaning. That's because washing and rinsing never removes quite all of whatever it is you're trying to wash off, and some of it will be in the water remaining after the last rinse. So you'd rather remove the water along with that part of the residue rather than evaporating it and leaving the residue behind. Admittedly this is a minor issue; it's not as if you were trying for total sterility or something. --Anonymous, 05:40 UTC, December 6.

Toothpaste foaming

I use BlanX toothpaste. Sometimes when I brush my teeth it fails to foam up but still becomes a liquid. I think this happens with other pastes too. Why? I can tell you that this happened after consuming cheap Tesco-brand gingerbread (the orangey hardish thin kind); I think it happens after eating other sugary foods too. Vitriol 22:36, 5 December 2006 (UTC)

Certain materials can act as antifoams - preventing foaming - notably some fats - that could be part of the answer.87.102.32.7 23:03, 5 December 2006 (UTC)

You are advised to wait some time if you can after eating, before you brush you teeth to allow the pH of your mouth to return to normal. I think it was on a chewing gum advert. I never like to brush my teeth too soon after eating but I might use an apple to hasten the process! --Username132 (talk) 23:29, 5 December 2006 (UTC)

By any chance did they also say that their gum neutralised the pH of the mouth? Vitriol 23:35, 5 December 2006 (UTC)

Oral bacteria thrive in more acidic conditions, and therefore would be less likely to occur in a basic mouth. Many toothpastes try to raise the pH of your saliva, as well as provide oxygen to the bacteria, as they are anaerobic bacteria. As for toothpaste not foaming, yes, that sometimes does happen for me. Just put more on the brush.--Russoc4 05:21, 6 December 2006 (UTC)

I agree -- trans fats are to be avoided if you like foam(ing). Theavatar3 18:20, 6 December 2006 (UTC)

How Many Trees?

How many trees are used to print the yellow pages?

One, if it's big enough! *ba-dum tish* Vitriol 23:23, 5 December 2006 (UTC)

There are two issues here:

1) The total amount of paper used.

2) The percentage of recycled paper.

I don't have the numbers on either, however. I personally think the phone companies should give customers the option to "opt out" of getting the paper copy, if they choose to use an online version, instead. The yellow pages are so packed with ads, though, that they may actually make a profit on them, so may be unwilling to offer an "opt out" option. StuRat 23:50, 5 December 2006 (UTC)

Isn't that the point of the Yellow Pages? Vitriol 00:52, 6 December 2006 (UTC)

As with many questions, the first thing you need to decide is WHICH Yellow Pages. All the ones in the US (apparently there are many)? Every single one in the world? Of course, if you want to consider the environmental impact of the Yellow Pages, you also have to consider other factors. Even if all the paper used is non-recycled, if the majority of old Yellow Pages are recycled, then this would arguably reduce the impact considerably. Obviously printing and transport/delivery costs need to be considered as well (in NZ we get new ones every year delivered to each house). Of course, for a proper analysis you'd also need to work out the subsequent cost of the Yellow Pages. Does it for example save people from driving around looking for something? Or does it encourage people to buy something or whatever which they won't otherwise (this can be good or bade depending on what they do) Nil Einne 10:56, 6 December 2006 (UTC)

December 6

Discworld's sun

This is a better question than my one about toothpaste... I think. This will involve making a bunch of assumptions. If the Discworld's sun is 80 miles in diameter, and the surface of the sun gives out as much light as our Sun does per square metre or what-have-you, and assuming you are observing the Discworld's surface at a point where the sun is directly above, how far would the sun have to be from the ground you're observing in order for it (the ground) to receive exactly the same amount of light a point directly below the Sun (pointing directly at the Sun?) on Earth gets? I'm confident there's a caveat somewhere that makes this unanswerable, and I'm kinda tired so my prose might be confusing, but it's worth asking, right? Vitriol 01:11, 6 December 2006 (UTC)

The sun has to have the same angular size in the sky, so take the radius of the earth's orbit and scale it down by the ratio of sum sun diameters. That ought to do it. Melchoir 01:25, 6 December 2006 (UTC)

I don't think I even know what that means. Vitriol 01:27, 6 December 2006 (UTC)

Which part? Maybe Angular diameter helps? Melchoir 01:30, 6 December 2006 (UTC)

There should be a sense of futility about trying to help a 15-year-old up at 1:35am with no formal maths education beyond year 8 (what's that in America? I'm English) figure it out himself. Save yourself! Vitriol 01:35, 6 December 2006 (UTC)

Translation: If Discworld's sun is a bazillion times smaller, it has to be a bazillion times closer. Clarityfiend 01:51, 6 December 2006 (UTC)

So I got to find the diameter of the Sun, and then... I guess I'll think about this tomorrow. Someone remind me. Vitriol 01:53, 6 December 2006 (UTC)

Cool. Don't worry, you already know all the maths you'll need. I, or someone else here, can help you with setting up the equation if you want. Melchoir 02:00, 6 December 2006 (UTC)

Let's see, assuming this sun is a G class main sequence star, 128.72 km is .00925 percent of the 1,392,000 km diameter of the Sun... 0.096176 AU or 14,387,860 kilometers. Roughly a tenth the distance that the Earth is at now.

I have a microsoft excel file that I used to figure this kind of stuff out. I don't remember all the equations necessary, but I'm sure the inverse square law factors in somewhere. Ƶ§œš¹ 08:10, 6 December 2006 (UTC)

Unfotunately the answer is miles out.

ok Suns diameter is 139200 km (1mile=1.6093km) so suns diameter = 864972miles . Discworlds sun is 80miles there for sun is 10812 times wider - so the surface area is 10812x10812 times more = ~117x10 times more. There is an inverse square law to distance meaning the discworld sun will need to be 10812 times nearer.. Suns distance is 92.95 million miles so discworld sun will need to be 92,950,000/10812 = 8600miles away. Does that match what Terry Pratchett says?83.100.138.168 09:28, 6 December 2006 (UTC)

I don't think he's said. I tried to figure it out, but then I got stuck and confused because Excel and Google gave me things like 3.5475926*10^6 (that's just an example) which I couldn't remember how to figure out, so I gave up. Vitriol 13:45, 6 December 2006 (UTC)

I wouldn't be surprised if Pratchett has worked this stuff out. Have you ever seen the Science of Discworld book(s)? You can't find them in the US, because we hate science, but I believe they're printed everywhere else. Melchoir 18:58, 6 December 2006 (UTC)

I agree with 83.100.138.168; it should be 8600 miles. Aeusoes1: I think you meant 14 387.860 km instead of 14,387,860 km, right? --Bowlhover 01:45, 7 December 2006 (UTC)

The Science of Discworld books don't have anything to do with this sort of thing. 80.169.64.22 17:05, 7 December 2006 (UTC)

protien

is milk protien broken during cooking tea?

Overheard conversation: I tell you, he's a complete fool in the kitchen. He can't cook tea without braking the protein! ;-) —Bromskloss 14:21, 6 December 2006 (UTC)

This is only a partial answer; hopefully someone can clarify. I doubt they're broken, but the probably do undergo denaturation... although I suppose it depends on the specific protein and the heat of the tea. -- SCZenz 17:18, 6 December 2006 (UTC)

Peptide bonds will not hydrolyse to a significant extent with a short, aqueous boiling treatment at atmospheric pressure. ike9898 17:50, 6 December 2006 (UTC)

Even if peptide bonds did break, the amino acids are still intact and ready to be absorbed and put to good use, right?

Many conditions that are sufficient to hydrolyzed peptide bonds will simultaneously destroy certain amino acids to a greater or lesser degree (BTW this makes accurate amino acid analysis quite difficult). There are also other possible reasons to care whether or not a protein is broken down. For example, hydrolyzed protein can be very bitter; not something you'd want in your tea. Hydrolysis can also alter a protien's 'functional properties; for example, it's ability to stabilize an emulsion. ike9898 20:39, 6 December 2006 (UTC)

Misplaced Pages

How many servers does wikipedia have? total? and how much CO2 is produced by the operation of each server? IE. How much electricity has to be produced via fossil fuels to power wikipedia for a period of 1 month? Should wikipedia be subject to some sort of "CO2 Tax"?13:47, 6 December 2006 (UTC)13:47, 6 December 2006 (UTC)172.145.152.76

Hehe, are you picking a fight? :-) How many servers and how much electrical energy? I don't know, probably somone else does. Even then, it might be difficult to say how much of it comes from fossil fuels. Tax? Probably not any more than for your own energy consumption (in proportion to how much you use, of course). —Bromskloss 14:14, 6 December 2006 (UTC)

Info on Wikimedia's servers is available here. --24.147.86.187 14:19, 6 December 2006 (UTC)

Many electric utilities have on their webpages a breakdown for the previous 12 months as to how much of their energy was produced by fossil fuels (oil, coal, natural gas), how much by nuclear, how much by hydro, and how much by solar, wind, etc. Some allow customers to pay extra to buy only green power. All the electricity is of course actually mixed together and fungible. The question is answerable. If the servers are separately metered, I could give an approximate answer if I knew the annual or monthly kilowatt hour usage. The air conditioning would need to be added, since they would overheat and shut down if not cooled, as well as the lighting and other necessary usage devoted to their operation. If they are in a dedicated facility, someone must be paying the electric bill. The nameplate rating on a computer is usually way above the actual usage, as it allows for startup load or worst case load. Edison 15:17, 6 December 2006 (UTC)

On the merits of a CO2 tax on Misplaced Pages, if such a tax were to be introduced, it would be most economically efficient to apply it to all CO2 emissions equally. That way, the lowest-cost ways to reduce CO2 emissions will be taken. Hypothetically, the Wikimedia Foundation might choose to switch to more expensive but more power-efficient servers, for instance, in response to higher power costs, or might choose to source their power from a non-emitting source. Or it might be cheaper to simply pay the tax - other people who can cut their emissions more cheaply will do so instead. --Robert Merkel 05:41, 7 December 2006 (UTC)

Old men with young hair

In Europe there are several politicians, like John Prescott, Silvio Berlusconi, and the german bloke whose name I cannot remember, who are quite old yet their hair has still not turned grey. John Prescott, for example, is 68 years old and yet he still has brown hair. The other two have black hair.

Could this be natural, or must it be the case that they dye it? What are the oldest, youngest, and average ages at which men's hair turns grey please? 81.104.12.23 15:44, 6 December 2006 (UTC)

I'd guess Grecian Formula. Politicians often have rather large sense of personal vanity.

Atlant 17:07, 6 December 2006 (UTC)

Helmut Schröder sued a newspaper, because they said things like dye or unnatural! So be careful!--Stone 17:18, 6 December 2006 (UTC)

You mean Gerhard Schröder :) Jack Daw 22:07, 7 December 2006 (UTC)

It's something to do with good food and fresh air and healthy relationships. Theavatar3 18:23, 6 December 2006 (UTC)

Prescott certainly enjoys a lot of good food. A lot of food in general, really. GeeJo ⁄_(c) • 18:31, 6 December 2006 (UTC)

Berlusconi is often mocked in Italian TV shows etc. as wearing a toupee or (more plausibly) for undergoing hair transplantation. Who knows… In a recent TV debate with Diliberto (http://www.repubblica.it/2006/c/sezioni/politica/versoelezioni35/berludili/berludili.html) there was the following brief dialog:

- host (E. Mentana): Ten years later I'm the only one with grey hair

- Berlusconi: I'll give you a good address, the more so because it's your duty to do something about it

- Diliberto: If we are going to talk about hair…

Ronald Reagan also had dark hair far enough into old age for it to be unlikely to have been natural. StuRat 12:54, 7 December 2006 (UTC)

Optional body parts

Last year, I ended up having my gallbladder removed. When I talked to my brother about it afterwards, he joked, "Are you planning on having any other non-essential body parts taken out?" This made me think that there are some organs that people have removed quite regularly and don't seem to have much of a negative affect on them afterwards. Besides the gallbladder, examples include tonsils and the appendix. I know that all of these organs have functions, but apparently, the body can get by just fine without them. So, what other bodily organs can be removed without much of a noticeable effect on a person's body? By this, I mean that the person must not usually be dependent upon drugs or other regular medical treatment after the organ is removed, and the person must not usually experience any significant negative effects from losing the organ after the surgery heals. —Cswrye 15:49, 6 December 2006 (UTC)

You can live without your Spleen and all organs you have two of, like one kidney, or one half of your lung. The rest you you should keep! Your gallbladder is used as storage for gall liquide which is important for digestion, without it fatty meals can give you some trouble. --Stone 15:57, 6 December 2006 (UTC)

Don't forget eyes, ears, tongue, nose, larynx, genitalia and tonsils. Each can be removed without requiring regular treatment after recovery, and your body would continue functioning perceftly adequately, though quality of life would be significantly impaired if they were all removed. GeeJo ⁄_(c) • 16:19, 6 December 2006 (UTC)

Remembering monty pythons movie, legs and arms are also disposable. Some of yor bones can go too!--Stone 16:47, 6 December 2006 (UTC)

A lot of things can go if you consider death to be only when your brain is shat on. — Preceding unsigned comment added by 216.164.192.159 (talk • contribs)

Keep in mind that one of my qualifications was "person must not usually experience any significant negative effects from losing the organ after the surgery heals." I would say that most of the things mentioned above would definitely provide some significant negative effects! The spleen and one kidney make sense, although I'm not sure about the lung. From what I've heard, it's possible to live with only one lung, but doing so can lead to some major impairments. —Cswrye 17:32, 6 December 2006 (UTC)

You mentioned "no drugs or treatment". What about replacements, such as a knee or hip replacement? Commonly, those remove part of the body and improve things afterward. --Kainaw 17:41, 6 December 2006 (UTC)

Hmm...I hadn't thought about that, but I guess that if you need a replacement, the body part wasn't really "optional" in the first place. So for the purposes of my question, replacements don't qualify. Teeth (mentioned below) is also a good one since it is fairly common to remove wisdom teeth, although you could only remove a few teeth before it began having a negative affect on your comfort and ability to chew food. —Cswrye 21:13, 6 December 2006 (UTC)

In my experience, teeth can be optional body parts. The more you lose, though, the less optional they become.

"The thing about control Ari, is that you don't realize how little of it you have until you have none of it at all." -- Malcom McDowell, Entourage.

Theavatar3 18:26, 6 December 2006 (UTC)

How about body fat, not really and organ but still! --Cody.Pope 19:28, 6 December 2006 (UTC)

You can live without a stomach, if you don't mind losing the ability to eat large meals. Laïka 19:47, 6 December 2006 (UTC)

I've read that the two big toes are the only ones that play a significant role in walking, so it's not too bad to lose the other eight. And then of course there's the hair! --Anonymous, 07:19 UTC, December 7. —The preceding unsigned comment was added by 66.96.28.244 (talk) 07:19, 7 December 2006 (UTC).

value of voltage in power supply

why the value of voltage of the power supply is always a multiple of 11? ex.-110v,220,440v,1100v.

Edison wanted 100v DC for home use. He allowed a 10% variance of 100-110v. Later, when he was able to better control line loss, he standardized it to 110v so you could be sure to get at least 100v. That was all DC. Tesla pushed AC and, apparently, the concept of 110v stuck. Of course, you can't send 110v very far down a line. So, it was stepped up. It is easy to step up/down in multiples, such as a 1-2 step up that changes 110v to 220v, or a 1000-1 step down that changes 110Kv to 110v. So, the reason for multiple is the coils in the step up/down transformers. I don't really know why the 110v standard stuck. --Kainaw 17:49, 6 December 2006 (UTC)

Thomas Edison used approximately 100 or 110 volts because wire could be insulated to that level easier than at 240, and because fatalities from accidental contact were much less likely at 110 than at over 200. He wanted to avoid low voltage bulbs, because the cost of the enormous copper conductors would have made it financially non-competitive with gas lighting. (Matthew Josephson, "Edison: a biography." McGraw Hill. New York, 1959, p194). Earlier inventors had been content to make a wire glow with large current (say 10 amperes) from a low voltage battery (say 10 volts), without looking at utility scale implementation. 110 is now a standard U.S. voltage at the point of use, that is, at the appliance, but not for the utility. A utility is required by its state commerce commission to provide typically 120v plus or minus 5 % for residential use at the point of interconnection, which is typically the utility meter. To be a low voltage violation, the utility supply would have to be below 114 volts for over 1 minute, to allow for motor startup current and to allow the utility's automatic voltage regulation equipment to respond to changes in load on a line. There is voltage drop within a residence, so 120 volts at the meter may drop to 110 by the time it gets to an air conditioner in the third floor bedroom at the opposite end of the house. When the voltage drops much below 110, there may be problems such as an air conditioner stalling and failing to come on, or a gas range failing to light, or a microwave not working, or a TV picture pulling in from the sides. Utilities may institute brownouts, in which the line voltage is intentionally decreased by several percent, on days when the supply of electricity is inadequate. At the decreased voltage, a resistive load such as a heater or incandescent bulb will automatically draw less energy. A motor load will typically draw more current at reduced voltage, but at an extreme low voltage it will stall and trip the circuit breaker or its own thermal relay, which also reduces the load on the utility. Sometimes increasing the size of the wire from the main panel to an airconditioner, or other motor load is all that is needed to keep it running on low voltage days. For power or other commercial load, 480 volts is a U.S. standard from the utility viewpoint, and typically allows a 10% variation. Various other voltages are standards from a delta-wye supply basis (208 volts phase to phase in a 3 phase system equals 120 volts phase to ground). Appliances or relay coils are sometimes sold on a "one size fits all" basis" so that one device is supposed to work on any voltage from 208 through 240 volts. If it is a range heating element, for instance, it may take an unacceptably long time to heat up at 208 and provide better service at 240 volts. Or a motor or other device it may work even in a 5% brownout if the source is normally 240, but fail to operate on a 5% brownout when the source voltage starts at 208. By being "early adopters" the U.S. was stuck with a voltage which requires more copper in every appliance cord and in wiring, and which does not allow a small kettle to boil the tea water as quickly as in the U.K or other 240 volt countries.Edison 18:33, 6 December 2006 (UTC)

glassified nuclear waste

Can glassified nuclear waste provide enough thermal energy to be used as a source of heat for distilling water and if so what is the ratio of distilled water to waste? Adaptron 19:13, 6 December 2006 (UTC)

Not sure if it is even hot, but it is called vitrification. X (DESK|How's my driving?) 20:29, 6 December 2006 (UTC)

Stealing from the article Nuclear Waste

Long-term storage of radioactive waste requires the stabilization of the waste into a form which will not react, nor degrade, for extended periods of time. One way to do this is through vitrification. Currently at Sellafield, the high-level waste (PUREX first cycle raffinate) is mixed with sugar and then calcined. Calcination involves passing the waste through a heated, rotating tube. The purposes of calcination are to evaporate the water from the waste, and de-nitrate the fission products to assist the stability of the glass produced.

The 'Calcine' generated is fed continuously into an induction heated furnace with fragmented glass. The resulting glass is a new subtance in which the waste products are bonded into the glass matrix when it solidifies. This product, as a molten fluid, is poured into stainless steel cylindrical containers ("cylinders") in a batch process. When cooled, the fluid solidifies ("vitrifies") into the glass. Such glass, after being formed, is very highly resistant to water. According to the ITU, it will require about 1 million years for 10% of such glass to dissolve in water.

What I get from this is that even when it is vitrified, some of it will dissolve in water. You probably could not use any water in which vitrified waste has been dumped safely because of radioactive contamination. Since some radioactive decay products are volatile, even if you used the radioactive waste to boil the water, radioactive stuff would get into the air and then into your distilled water. This didn't answer any of you original questions because I don't know how hot radioactive waste gets but you could figure out on average how much glass would dissolve into the impurified water on average into a given period of time. Sifaka 21:04, 6 December 2006 (UTC)

What makes you think that water must be in direct contact with vitrified nuclear waste in order to extract the heat produced by the waste? Indirect thermal transfer can be accomplished by any number of inert solid, liquid or gaseous materials in much the same way as in a nuclear power plant where the water used to make the steam to drive the turbines is not the same water that is heated by fission of the nuclear fuel. Perhaps I should have asked what the temperature and enthalpy of the stainless steel containers is once they have been filled with nuclear waste? Adaptron 22:38, 6 December 2006 (UTC)

You are right about that, but you still need to find the answer to your original question about how much heat energy the radioactive material is putting out in order to begin to figure out how much heat energy would be transfered to the water. I afraid I have no idea in the least. Sifaka 23:04, 6 December 2006 (UTC)

I recall reading somewhere that the waste maintains a high temperature of around 800 deg. F (don't think it was deg. C) for a very long time. Adaptron 05:01, 7 December 2006 (UTC)

Salting the earth

Hi,

just curious about this: why salting the earth makes it infertile? —Gennaro Prota 20:00, 6 December 2006 (UTC)

Too high a salt concentration kills plants. If the soil is more salty than that toxic level...infertile. There's some info scattered in the text and footnote refs on this page I found by chasing a few wikilinks from your starting point. DMacks 20:09, 6 December 2006 (UTC)

And salt kills plants by sucking out water from their roots, dehydrating them. See osmosis; basically, since the concentration of water is less in salt water then in pure water, the water in the plant's cells will move out. --Bowlhover 20:31, 6 December 2006 (UTC)

Thank you very much to both of you! I had a feeling it had to do with water but wasn't sure exactly how. Incidentally, I'm glad to see that the article about osmosis is quite above the average level :-) —Gennaro Prota 23:22, 6 December 2006 (UTC)

It must have absorbed good info from the various editors. StuRat 12:44, 7 December 2006 (UTC)

Solar energy

What will happen when solar energy uses the sun up?

See Sun#Life cycle. —Keenan Pepper 22:06, 6 December 2006 (UTC)

The Sun

Will man ever walk on the sun?

No its too hot--Light current 22:14, 6 December 2006 (UTC)

And because it is a huge ball of gas and plasma, it doesn't have a surface to walk on anyway - read Sun for more info. Gandalf61 22:58, 6 December 2006 (UTC)

Somewhere towards the middle it must be so dense that a human would be unable to break surface tension or whatever. But yeh, still its impossible. Philc _TC 23:07, 6 December 2006 (UTC)

There's no surface tension because there's no surface, just a gradual density gradient. If you tried to stand on the sun, all the elements of your body would be vaporized and mix with the sun, and then the heavy elements (everything other than hydrogen) would slowly sink all the way down to the core. —Keenan Pepper 01:13, 7 December 2006 (UTC)

A some time in the very distant future, won't the Sun burn out, shrink (possibly after initially expanding) and cool down? Perhaps it would be possible to walk on it then, although by that time humans will either be extinct or have elvolved into something else I imagine. 81.104.12.7 23:42, 6 December 2006 (UTC)

Sure, if you don't mind weighing 276 000 times heavier than you normally do! Something as massive as the Sun (a white dwarf) that's the same size as Earth has very strong gravity at its surface. --Bowlhover 01:34, 7 December 2006 (UTC)

This be from an Ali G watcher, I betcha --24.147.86.187 03:15, 7 December 2006 (UTC)

If the sun were a tad heavier (maybe 35% more), it could theoretically collapse to a Neutron star. Neutron stars have a solid crust, but most emit lethal doses of radiation, and even just lifting your little finger 1 centimetre would require as much energy as 72 climbs of Mount Everest. Laïka 17:45, 7 December 2006 (UTC)

P.O.E.R.K.W.I.U.

What does P.O.E.R.K.W.I.U. stand for?

Whatever it is it's not something often used. Google had no hits for either that or POERKWIU. Make sure it is spelled right, and if it is, it probably only has meaning to the person who created it. Sifaka 00:01, 7 December 2006 (UTC)

Context would help - where was it used? Confusing Manifestation 01:39, 7 December 2006 (UTC)

Silicon in Diode

Roughly what are the dimensions of the silicon crystal in a diode. Philc _TC 22:18, 6 December 2006 (UTC)

Well it does depend on the type and rating of the diode. See diode closeup--Light current 23:14, 6 December 2006 (UTC)

Would you say 1x1x5mm is a fair guess? Philc _TC 23:51, 6 December 2006 (UTC)

More like 1 * 1 * 0.5 mm and that could be a biggie. Depends on heatsinking etc--Light current 00:02, 7 December 2006 (UTC)

Birth Control

Are the side effects of Necon 7/7/7 and NuvaRing approximately the same? (I've had prescriptions for both, so no worries about the doctor part. I'm just wondering.) 71.220.122.230 23:41, 6 December 2006 (UTC)

Sorry, we don't do medical advice. Try WebMD or ask a doctor. Friday (talk) 00:29, 7 December 2006 (UTC)

It's not advice I'm asking for, I'm just wondering. Your answering of this question affects nothing in my life except fulfilling my curiosity. 71.220.122.230 00:53, 7 December 2006 (UTC)

Not everyone here is a doctor, and therefore not everyone can give factual information. There is a chance that you can be misinformed, and regardless of the use of the knowledge we share, there are liability issues involved. Some times we let small things slip, but questions like yours are best left to qualified professionals. Sorry.--Russoc4 00:57, 7 December 2006 (UTC)

Fine. I just won't ever know. 71.220.122.230 01:00, 7 December 2006 (UTC)

Just ask a doctor, or a local pharmacy, as long as they have "real" pharmacists who know what they are doing. --Russoc4 01:03, 7 December 2006 (UTC)

Boy, are these medical disclaimers annoying. You might have better luck searching the Internet for their detailed patient labeling, which will contain risks and side effects of each. It might also be worthwhile to search Medline (or something similar) to see if they've been compared in a decent randomized controlled trial, which ought to give you a good idea of how they compare head-to-head. --David Iberri (talk) 01:27, 7 December 2006 (UTC)

Thank you, I didn't know about Medline. I'll look there. 71.220.122.230 02:16, 7 December 2006 (UTC)

The Food and Drug Administration website often has good information for drugs, particularly if there was a recent FDA-issued safety warning. Third on the list at this webpage is a 2005 safety labeling change for NuvaRing. The Department of Health and Human Services website is another good source of information; there is a page with some information for the hormone combination in brands such as Necon. --JWSchmidt 03:06, 7 December 2006 (UTC)

Try a PDR, you can find one at a bookstore or maybe a library, or maybe at www.PDR.net. 71.88.110.87 12:04, 7 December 2006 (UTC)

What will humans look like in a billion years time?

Has anyone ever done any serious scientific thinking about what humans will look like in the distant future? —The preceding unsigned comment was added by 81.104.12.7 (talk • contribs).

A cynical extrapolation of current trends would suggest that we turn into large balls of fat with vestigial legs but massive sexual characteristics. I hope that won't be true. 81.104.12.7 23:49, 6 December 2006 (UTC)

There is a good chance that humans won't exist anymore as we know ourselves. We could wipe ourselves out, or some natural event could wipe us out, natural selection pressures could have caused us to evolve, or humans could have tampered with their own genome enough so that we become completely unrecognizable. Or we could somehow stay the same... A billion years is a long time, and lots of stuff can happen in it. Sifaka 23:58, 6 December 2006 (UTC)

We'd probably just mind transfer ourselves into machines by then. So we could look like anything. ☢ Ҡi∊ff⌇↯ 00:56, 7 December 2006 (UTC)

Oliver Curry says the race will split in two. —Keenan Pepper 01:17, 7 December 2006 (UTC)

Clearly the gnome-guys would be the future of humanity. Vitriol 01:26, 7 December 2006 (UTC)

For the record, lots of people said it before that dufus did. I'm not sure why he got so much attention? Lee Silver actually gave the question real serious thought in his best-selling book Remaking Eden many years ago now. Curry seems like a total moron when it comes to evolutionary thinking in comparison. --24.147.86.187 03:13, 7 December 2006 (UTC)

It would amuse me if that happened, then some natural disaster kills off the frail former upper-class leaving the robust former working-class to evolve and become small, furry, and quadrupedal before another intelligent species emerges and starts exterminating them as pests before keeping some of them as pets and laboratory animals. Vitriol 03:46, 7 December 2006 (UTC)

H.G. Wells came up with the "two species" idea in his 1895 novel The Time Machine - in the far future, the human race has split into the Eloi and the Morlocks. Gandalf61 10:33, 7 December 2006 (UTC)

I go with the BORG idea. There are some chemical and biological process which have taken billions of years to develop naturally that machines might never do as well whereas the ability to see images in every single wavelength of the spectrum including possibly extremely long wavelegths like sound are on the other hand abilities that only man made electronics seem to possess. Adaptron 05:08, 7 December 2006 (UTC)

The timescale you're talking about is just too vast to make any sensible predictions. It's very difficult to predict the advancement of technology a decade in advance. --Robert Merkel 05:32, 7 December 2006 (UTC)

My bet is extinct. After barely three centuries of modern science we've only barely managed to avoid killing ourselves and destroying all usable resources on the planet, and we show no real ability to manage ourselves in the long-term. It seems more likely that someone will come up with a new way and new rationale for killing everyone before then. --140.247.251.173 16:46, 7 December 2006 (UTC)

While I wish I were more optimistic, my guess is "dust" with a scattering of fossils in geologically stable parts of the world. The Fermi paradox is a haunting one: life may well kill itself off wherever it appears, but that's just my dark thought at present time.

There is a fine Arthur C. Clarke novel set a billion years in the future: Against the Fall of Night (wondering if that link will turn blue? I do like Misplaced Pages after all...) Antandrus (talk) 16:52, 7 December 2006 (UTC)

"What will humans look like in a billion years time?"

Very old. —B00P 20:56, 7 December 2006 (UTC)

December 7

Runny nose in cold weather

Why does my nose run when I am outside in the cold. J. Finkelstein 00:21, 7 December 2006 (UTC)

Cold air tends to be very dry. Your nasal passages create moisture to keep from drying out. If you spend most of your time in the cold, your nasal passages will get used to it and your nose won't run as much. A similar thing happens in the desert. When I was in 29 Palms, we called it newbie snot because the new guys always had a "cold" - which was actually just a runny nose. --Kainaw 01:25, 7 December 2006 (UTC)

Heh. Happens to me everytime I change climates. X (DESK|How's my driving?) 04:43, 7 December 2006 (UTC)

Near and Far - The Automobile Rearview Mirror

I need glasses to read type at a close distance, and can see fairly clearly at a distance. However, my rearview mirror in the car is out of focus on its edges, yet the image of a vehicle several hundred yards behind me remains crystal clear. How can the image I see on the outer portion of the mirror be "out of focus" but the image on the mirror be so clear? 70.181.28.145 00:45, 7 December 2006 (UTC)--70.181.28.145 00:45, 7 December 2006 (UTC)Aloyshai

I would think it's because of imperfections in the mirror, and not because of your eyesight. --Bowlhover 01:53, 7 December 2006 (UTC)

When you look into a mirror at something's reflection, you're not looking at the surface of the mirror, you're looking at the virtual image behind the mirror. The virtual image is farther away than the mirror's surface, so you can see it more clearly. In other words, your farsightedness allows you to see objects as long as the light from them travels more than a certain minimum distance. The light from the mirror's surface only travels a short distance to your eye, but the light from a distant object travels a long way to the mirror first, so the total distance is enough for you to see it clearly. —Keenan Pepper 02:31, 7 December 2006 (UTC)

But the point is, the original poster doesn't see things in the mirror clearly, even though he sees them clearly without the mirror. --Bowlhover 03:00, 7 December 2006 (UTC)

I think you misread it and Keenan has it right. --Anon, 07:22 UTC, December 7. —The preceding unsigned comment was added by 66.96.28.244 (talk) 07:22, 7 December 2006 (UTC).

Moon

I have two questions: First Is it possible for balloon craft to still work on the moon or will it not work because there is no Air? Second is it possible to collect condensation from the moon from any atmosphere that is there by heating a plate and colling it? Thank You for any answers.

Balloon craft only work because they float on air. If there is no air, they'll drop as fast as anything else. Also, it's not possible to collect condensation on the Moon because there's no water vapour, and you need water vapour for condensation to occur. --Bowlhover 01:49, 7 December 2006 (UTC)

As far as has been ascertained there is minimal atmosphere around the moon. So the answer to both Qs is NO!--Light current 01:53, 7 December 2006 (UTC)

See: Moon#Presence of water. --JWSchmidt 02:39, 7 December 2006 (UTC)

NAD+ turning into NADH

I was trying to understand the concept of energy harvest via NADH and the electron transport chain, but I don't understand a particular step. Whenever the NAD+ accepts the two H+ ions and two electrons I can never figure out where the H+ ions came from. I've read that they come off of the substrate being broken down, like glucose. However, in all of the chemical equations, once the NAD+ has accepted its hydrogen ions and electrons, the original substrate molecule doesn't seem to have lost these. What am I missing? Thank you.

Our article on NAD+ may clarify things. The article also links to a Flash animation which may help. The original substrate molecule (which is oxidized) definitely does have to give up the hydrogen. TenOfAllTrades(talk) 04:07, 7 December 2006 (UTC)

I read the article and watched the flash animation, but I still am a little bit lost. Perhaps I've just read a typo, but the book I've been reading shows no change in the substrate's number of hydrogens after it has given them up. Additionally, it states that two hydrogens are given up, rather than the one that is explained in the flash animation. An example is converting pyruvate into Acetyl CoA. My book shows pyruvate as C3H3O3 - then shedding a CO2 to C2H3O - then shedding the hydrogen for NADH - and finally adding in Coenzyme A. However, the book still shows 3 hydrogen on the newly formed Acetyl CoA.

Yeah, the Flash animation oversimplifies a bit—it doesn't mention the hydrogen atom that is dumped into solution. Okay, to find the missing hydrogen, you can start with the structures for acetyl-CoA, CoA, and pyruvate, and try to work out where the missing atoms go.

Or, you can note that biologists are sloppy about their terminology. Pyruvic acid is C₃H₄O₃. Its dissociation into pyruvate ion therefore produces C₃H₃O₃ and H. If you look at the structural formulae in our article on glycolysis (and probably in many textbooks) you'll find that the structure labelled as pyruvate is actually the undissociated pyruvic acid. So the reason why you're missing a hydrogen atom is that your formulae for pyruvate has already accounted for the proton that wanders off into solution. Meanwhile, the other hydrogen atom comes from the thiol (-SH) tail of the CoA; that hydrogen is lost when the sulfer atom forms the bridge between the acetyl group and CoA. TenOfAllTrades(talk) 05:36, 7 December 2006 (UTC)

Ionosphere page

Hello,

I was wondering where the page for the Ionosphere went. Did it get deleted for vandalism or something? I hope I spelt it right, but on word it doesn't show up a typo.

from Jinglebells ( I'm not a member here but didn't want to sign my real name) —The preceding unsigned comment was added by 58.107.41.170 (talk) 05:33, 7 December 2006 (UTC).

Seems ok: Ionosphere. Cheers, Antandrus (talk) 05:34, 7 December 2006 (UTC)

No one is expected to sign their real name. Just type four tildes. This can help us trace problems.--Shantavira 09:31, 7 December 2006 (UTC)

Driving behind a truck

It was mentioned to me that it is more fuel-efficient when driving to drive behind a truck, because the vacuum behind the truck helps to "suck" the car along. So I was wondering about a few things, because it sounds a little dubious to me.

• 1) How long would the cone of low air pressure be behind a large truck travelling at say, 100km/h? (For the effect to work, it would obviously have to be long enough to partly contain a car, plus a safe following distance)

• 2) Wouldn't there probably be sufficient air sucked under the truck and out the back to negate the effect?

• 3) Supposing that the cone was long enough and that there was negligible air sucked under the truck, would there be any noticeable difference - i.e., would the air pressure difference make a sufficient contribution to the work performed by the engine? BenC7 06:21, 7 December 2006 (UTC)

It doesn't have to be a truck. They do that a lot in the Tour de France. See Drafting (racing). Can't help you with the details though. Clarityfiend 06:42, 7 December 2006 (UTC)

Back when I rode a three-speed bicycle and they had trolleybuses in this city, I used to draft behind them at speeds up to about 25 mph. The effect was significant if I got close enough to the trolleybus -- I think I tried to stay within 5-10 feet for as long as I could, and the effect dropped off rapidly when it got above my top speed and pulled ahead. (There was no significant risk in following so close, as I could hear the trolleybus's motor and air brakes and respond quickly, and of course there were no exhaust fumes.) I have no idea of how to extrapolate this to larger vehicles and higher speeds, though. --Anonymous, 08:30 UTC, December 7. —The preceding unsigned comment was added by 66.96.28.244 (talk) 08:30, 7 December 2006 (UTC).

Believe it or not, there's actually very little experimental data about the size of truck wakes, so it's difficult to answer the question, but I'll answer the question about the generic effect. As to whether the effect would be negated, think of it this way, in a stationary frame of reference. Until the truck impacts with an amount of air, it is stationary, so upon impact it is given a net forward momentum. This means that the following car will have to do less work when it collides with the same air. Any air that comes from under the truck would be there anyway if the car was alone on the road, so the effect couldn't be negated. Close to the truck, it's wake will be dominant over any air flowing underneath. Of course the further back you get, the smaller the wake will become. In general the effect is significant and measurable, as long as the following car is close enough to be in the wake. Readro 08:49, 7 December 2006 (UTC)

Never heard it called drafting before - you should look at Slipstream - a similar term. The car infront pushes the air in front out of the way (a bit like a piston) - if you are close behind (a few metres or less) you can follow in it's wake as others have said. Have you never noticed a strong wind as a fast big truck goes by, or even better stand on a train platform as an express train goes through - they really 'suck' literally.83.100.174.147 11:38, 7 December 2006 (UTC)

1. Not a very long cone - probably not safe unless you are a racing driver - see however road train.

2 Depends on how high the truck rides - many european trucks have skirting so even if you're in a low slung car you should still get sucked along..

3 Yes - at high speeds you would be in a low pressure area - which does effect engine performance.

Sorry I can't give you any solid figures.83.100.174.147 11:44, 7 December 2006 (UTC)

While there may be a fuel efficiency gain, I must advise against following a truck so closely, for numerous safety reasons:

• The turbulence behind the truck could make driving difficult and dangerous.

• The truck may stop suddenly, leaving you insufficient time to react.

• Your view of the road ahead will be obscured by the truck, causing you to be unprepared for upcoming dangers.

• Water or road debris kicked up by the truck tires may strike your car, doing body damage, temporarily blinding you, smashing the windshield, etc. —The preceding unsigned comment was added by StuRat (talk • contribs) 12:31, 7 December 2006 (UTC).

Actually, if you follow close enough, this last one is unlikely, especially if the truck has mud flaps. The debris would pass through the gap between the mud flap and the road, giving it a flatter trajectory, so you would be more likely to be hit if you were further back.

In addition, such tailgating is rude, and the truck driver will be annoyed.

Yes, ever see the bumper sticker - 'If you can't see my mirrors, I can't see you'?

StuRat 12:26, 7 December 2006 (UTC)

Yes and illegal (in some countries at least) for the reasons given above.83.100.174.147 12:36, 7 December 2006 (UTC)

If an 18 wheeler is driving along with the back open, is it windier inside the trailer, or on top? --18.90.5.3 16:42, 7 December 2006 (UTC)

Data communication and Network

Hello sir I want to have some help from u. My questions are

1.How group leadres use to work in KaZaA, what are their responsibilities and how they used to lead their group in perfect manners?

2.what is bootstraping in KaZaA and how it works?

3.what is itrative model in DNS( Domain Name Server ) and what is the recursive model in DNS?

4.how Gnutella works and how bootstraping occures in Gnutella?

5.What is TLD( Top Level Domain Name Server ) in DNS and how it works?

6.What is DHCP( Dymanic Host configuration Protocol )? —The preceding unsigned comment was added by Honey65 (talk • contribs) 06:46, 7 December 2006 (UTC).

Definately you should ask on the computing page Misplaced Pages:Reference desk/Computing83.100.174.147 11:33, 7 December 2006 (UTC)

Also be aware that we don't do homework questions here (assuming this is what it is). They'll send you in the right direction over at the computing reference desk though. For now try: Gnutella P2P and DNS. Benbread 13:06, 7 December 2006 (UTC)

the homeostatic nature of skin repair.

when the skin is injured, how does homeostasis play a role in its repair? —The preceding unsigned comment was added by 81.154.244.237 (talk) 10:42, 7 December 2006 (UTC).

Well, let's do our own homework okay? Maybe you should take a look at the article on skin and see if it sheds any light on it. Laurən 18:42, 7 December 2006 (UTC)

Scooting

Why do dogs scoot? Dismas| 11:19, 7 December 2006 (UTC)

Worms? or for fun - am I describing the same thing?83.100.174.147 11:32, 7 December 2006 (UTC)

I thought the answer was something along the lines of, "If you could, you'd never leave the house." --Kainaw 13:25, 7 December 2006 (UTC)

You might find something useful in anal glands, assuming the above repartee failed to answer your question. Apparently, one of the reasons for a dog to scoot lies in discomfort caused by overly full anal glands. -- Ec5618 16:16, 7 December 2006 (UTC)

how..................

i need more information about diabetes........n its types(type 1,type 2 and gestational...)culd u plzzz add sum more information.....which give in a nut shell......?'coz i need it for my board xam...... —The preceding unsigned comment was added by 220.226.140.51 (talk) 13:28, 7 December 2006 (UTC).

Have you considered reading the article on diabetes? --Kainaw 13:43, 7 December 2006 (UTC)

"Board exam"? Does anyone else find this a deeply disturbing inquiry? alteripse 17:53, 7 December 2006 (UTC)

Not me. I'm too jaded from past RD questions. --Kainaw 18:18, 7 December 2006 (UTC)

Atmospheric chemistry units

I would like to know what molecules per square centimeter/second means, when talking about chemical reactions in the atmosphere.

Liza (uni student)

originally posted by User:195.215.9.140 at Misplaced Pages:Requested articles/Natural Sciences --User:Ceyockey (talk to me) 14:32, 7 December 2006 (UTC)

It might be a flux; does that article help? Melchoir 16:11, 7 December 2006 (UTC)

Calculating a change in temperature during irreversible adiabatic expansion.

I know it should be relatively trivial to calculate the change in temperature of an adiabatically expanding gas, but I just can't seem to figure it out. If I know, for example, that 1 mol of gas expands from a pressure of 30 atm to 10 atm, irreversibly and adiabatically, do I then have enough to calculate the work done by the gas? What other parameters do I need to know? What formula can I use?

As I said, I have a feeling the answer is relatively simple, but it eludes me and the puzzle is beginning to bug me. Thanks. -- Ec5618 16:12, 7 December 2006 (UTC)

"Irreversible" could mean many things. If you're asking about a sudden expansion due to, say, a removed partition, then the gas does no work, since its bounding walls don't move in the direction it's pushing. Another way to see this is that its internal energy doesn't change, and since no heat is transferred by assumption, no work is done either. Melchoir 16:18, 7 December 2006 (UTC)

...so, to hit on your other questions, I guess the parameter you need to know is the work done by the gas! Or, at least, a description of the physical situation that allows you to figure it out on physical grounds, not necessarily through any particular equation. And once you know the work, you know the change in internal energy, which directly gives you the change in temperature. Melchoir 16:21, 7 December 2006 (UTC)

Ah no, work may be done on a partition that is suddenly free to move, or that is suddenly moved outward. This forces the gas to expand, and thus to do work on the surroundings. The only scenario on which no work is done, as I understand it, is one in which the expansion is into a vacuum, as the external pressure would then be 0. Work, after all, equals external pressure times change in volume, assuming thr external pressure is constant.

And yes, I had come to the conclusion that it was the work that must be found. I had thought the situation was clear. A chamber containing a single mol of gas is forcibly expanded so that the pressure drops. Work is done, and it is equal to the change in internal energy. The change of temperature then follows from the heat capacity of the gas, which I can probably find in a table somewhere.

What exactly is unclear? -- Ec5618 16:34, 7 December 2006 (UTC)

Well, I did say in the no-work situation that the bounding walls don't move in the direction it's pushing. You can accomplish this by sliding away a partition or deactivating a force field in a large box, allowing the gas to explore a greater volume. There will still be a vacuum present in the problem, but it's a different physical situation.

If you're dealing with a forcibly expanded chamber, it depends on what external agent is applying the force, and how much work it does or absorbs itself. Assuming that the compound system of chamber + agent + outside atmosphere itself evolves reversibly, then the work done by the irreversibly expanding gas plus the work done by the agent should equal the work that a reversibly expanding gas would have done. Melchoir 16:57, 7 December 2006 (UTC)

Hmm, thank you, but I'm still puzzled. Suppose, if you will, that my setup is a bit more complicated. I have a box of gas at 30 atm. Given that the outside pressure is just 10 atm, the gas excerts force on the walls of the box. If I now allow my box to expand, the gas will do work on the surroundings, without the need for additional work. The box will expand until the pressure is normalised; that is, the pressure in the box will drop to 10 atm. How much work will the gas have done, assuming that the gas expands adiabatically and irreversibly, and that the box contains just one mol of gas? The answer will require some calculations, but without the right formulas, I'm stuck. -- Ec5618 17:36, 7 December 2006 (UTC)

How could you forget pV=nRT?

See ideal gas law (use this approximation please until you feel more confident) If a gas expands adiabatically then no energy is exchanged , and it can be shown that for an ideal gas pV is proportional to energy. So your gas will expand to three times its volume as the pressure drops to one third of its original pressure. (note this is a response to your original question)

For work done take a look at http://www.grc.nasa.gov/WWW/K-12/airplane/work2.html

If you let the gas do work as it expands it may loose some energy. You need the initial volume or temperature of the gas to proceed further here. Using pV=nRT (n=number of moles, R is a constant, p the pressure) with one more of the two the system can then be fully described.

The work done is Integral (Vbegin to Vend) of P(at volume V) x dV.83.100.174.147 17:50, 7 December 2006 (UTC) Please comment as to whether this helps/makes sense..83.100.174.147 17:51, 7 December 2006 (UTC)

Thank you for your help, but pV = constant only when T is constant. When the gas expands adiabatically, T changes, because the system does work, as per ${\displaystyle \Delta T=\Delta U\times C_{v}}$ (and in an adiabatic change, the internal energy is equal to the work done, as per ${\displaystyle \Delta U=q+w}$).

Now, you're right in saying that I could easily calculate the work if I knew the initial and the final volume of the gas, but for the purpose of this calcation I am assuming that the change in pressure is given, not the change in volume. I have tried to use ${\displaystyle w=p_{e}\Delta V=p_{e}(V_{f}-V_{i})=p_{e}({\frac {nRT_{f}}{p_{f}}}-{\frac {nRT_{i}}{p_{i}}})=p_{e}\times nR({\frac {T_{f}}{p_{f}}}-{\frac {T_{i}}{p_{i}}})}$ but since the change of temperature is unknown, I am stumped. -- Ec5618 19:17, 7 December 2006 (UTC)

Isn't it delta U = delta T x C (specific heat is Joules per kelvin,yes? deliberate mistakes - I make them..). With two unknowns (temperature and volume) you are surely stumped.83.100.174.147 20:29, 7 December 2006 (UTC)

Hmm, then what about a leaking gastank, for example? If a gastank containing gas at 30 atm springs a leak into an infinite chamber at 10 atm, is it impossible to calculate the temperature of the expanding gas? In this case, volume is irrelevant, and, assuming the change happens quickly enough, the change is adiabatic. Are you saying it would be impossible to calculate the temperature the gas would reach?

You're right, about the equation being backwards, of course.

I still find it hard to believe that it would be easy to calculate work when only the external pressure and the change of volume are known, but impossible when the external pressure and the change of pressure are known. Surely this sort of problem should be routine, in some way. -- Ec5618 20:50, 7 December 2006 (UTC)

your gas tank - yes I think it's impossible to calculate the temperature of the released gas without knowing it's original temperature. Maybe it would be possible to calculate the temperature change (ie the temperature drop).

Your third point - in the first example P(external) and V(change) are known (two variabels), in the second P (external) and P (change) are known that's only one type of variable - I think that's where the difference lies. Maybe you should ask think point again - I think it's explainable but I'm not very good at it.87.102.36.136 22:23, 7 December 2006 (UTC)

Magnets

hello, if I have lactate with an iron atom on it, or maybe EDTA with iron captured inside, with concentrations on the order of parts per billion, can I use a magnet to control these molecules? How big/small would thi s magnet need to eb? Thanks. -Steve —The preceding unsigned comment was added by 74.134.95.124 (talk) 17:24, 7 December 2006 (UTC).

I'm afraid not. The reason metal is affected by a magnetic field is that several atoms of the metal have the same alignment. A substance containing single atoms of metal will not be affected, as it will not be magnetic. See magnet. -- Ec5618 17:42, 7 December 2006 (UTC)

Suggest tentatively ignore the above.

The iron complex of edta or lactate should/will be paramagnetic - it will be attracted to a magnet. The concentration is relatively irrelevant here I think. But you would need a very big magnet to control the molecules - to control the molecules the force would have to be sufficient to overcome diffusion in the liquid. I can't give you a figure but expect 10tesla or more.

See Paramagnetism I think there should be enough data there to start calculating approximate figures.

There is a force an paramagnets resulting from magnetic fields - but don't expect it to be very great. Hope this helps.83.100.174.147 17:58, 7 December 2006 (UTC)

effect of oil spills on frogs

What is the primary effect that an oil spill would have on frogs? —The preceding unsigned comment was added by 86.42.77.243 (talk) 16:39, 7 December 2006 (UTC).

I'm afraid your question is rather vague, and it seems like a homework question. Oddly, we don't seem to have a lot of information on his topci in our oil spill article, but an obvious result of an oil spill on local animal life is death. -- Ec5618 16:48, 7 December 2006 (UTC)

High tension transmission

We don't appear to have an article on this and I'm looking into it for some school stuff. I found EHT but it's a stub and I'm not totally sure that's it's the same thing. I've searched on Google and can't find anything useful that I can understand so would appreciate advice on where to look, or at least what this concept is. —Xyrael / 17:03, 7 December 2006 (UTC)

Is this possibly related to HVDC? —Bromskloss 17:10, 7 December 2006 (UTC)

Power engineering contains some info.--Light current 17:17, 7 December 2006 (UTC)

I seem to be unable to locate any information on this specifically, as it doesn't appear to be HVDC - I don't think that power lines use AC all the way through. As for the latter page, I've looked through and can't spot it - what is it under? Thanks. —Xyrael / 18:00, 7 December 2006 (UTC)

Could you more specific about what you need to know if Electric power transmission doesnt cover it??--Light current 18:09, 7 December 2006 (UTC)

See also Overhead powerline. If you have further questions after reading these article, then we will attempt to assist you to find answers. Edison 18:50, 7 December 2006 (UTC)

herbs

Could you please tell me and edible herb that is best used when the moon if full? Thank you for your help! —The preceding unsigned comment was added by 172.141.41.43 (talk) 17:57, 7 December 2006 (UTC).

Best used for what?--Light current 18:10, 7 December 2006 (UTC)

If you believe the myths, garlic is potent werewolf repellent, as well as a vampire repellent, which would be very useful during the full moon. Wolfsbane would be even better, although it is not edible but deadly poisonous... Laïka 18:16, 7 December 2006 (UTC)

Hypothermia

In light of James Kim's death, I was just thinking about hypothermia. It says that he may have removed his clothing in a futile attempt to cool down because one of the stages of the condition involves overheating. I was wondering whether it's wiser to keep the clothes on, despite the heat, or if it doesn't matter either way? - Pyro19 18:54, 7 December 2006 (UTC)

See Hypothermia. I don't see that the article addresses the issue of victims feeling warm, but the article makes it clear that the victims need to be warmed up, so I'd assume this applies even if they feel hot. Friday (talk) 19:00, 7 December 2006 (UTC)

Yes, it has been observed (in some cases) that the victims of Hypothermia have undressed. This paper quotes another which suggested an explanation: "when core body temperature falls to a critical level, peripheral vasoconstriction fails. The resulting sudden vasodilation could lead to an exaggerated sensation of heat and a consequent attempt by the victim to undress". This is only an educated guess, however, and the reported undressing may simply be an artifact of the general delirium brought about by the hypothermia. Note that if this is true, it's a sensation of overheating, not the real thing. Clearly it's wiser to keep the clothes on, but by that point the person is likely to be quite seriously altered, and prone to doing unwise things. -- Finlay McWalter | Talk 19:12, 7 December 2006 (UTC)

My understanding, however, is that rescuers felt that Mr Kim's discarded clothing had been arranged in a deliberate manner, such that it seemed intended as a sign. That wouldn't be consistent with a delirious person haphazardly discarding clothing in the throes of such false fever. -- Finlay McWalter | Talk 19:19, 7 December 2006 (UTC)

CAPITAL PUNISHMENT METHODS

HOW MANY DIFFERENT WAYS HAVE PRISONERS BEEN EXECUTED BY GOVERNMENT AGENCIES AND WHAT IS WRONG WITH PUTTING THE PERSON IN A HYPERBARIC CHAMBER AND PUMPING THE AIR OUT THUS DEPRIVING THE BRAIN OF OXYGEN AND CAUSING A HUMANE AND PEACEFUL DEATH? —The preceding unsigned comment was added by 70.226.82.194 (talk) 19:38, 7 December 2006 (UTC).

Misplaced Pages has a list of methods of capital punishment, which includes twenty or thirty different methods. The Capital punishment in the United States article links to this page with a list of methods by U.S. state. It looks like lethal injection is far and away most common. As for asphyxia, perhaps it's not as humane and peaceful as you think. Have you tried it? -- Plutor  20:20, 7 December 2006 (UTC)

HUMANE according to whom? 202.168.50.40 21:15, 7 December 2006 (UTC)

Should we have a "CAPITAL" punishment here? –mysid☎ 21:36, 7 December 2006 (UTC)

Looking for the name of a disease

I'm looking for the name of a "disease": newborn babies born with hard brittle skin, bloodred eyes. They're almost intolerable to look at. Anyone know the name? Jack Daw 20:11, 7 December 2006 (UTC)

Harlequin fetus  ?Namlemez 21:39, 7 December 2006 (UTC)

That's it, thanks. Jack Daw 22:24, 7 December 2006 (UTC)

Weight/force

I have a 25-ton object that I want to lift and move. I have a crane that can handle a 75-ton load. Can the crane, from 65 feet away, at a 90 degree angle, lift the object up 45 degrees and move it to clear a building? How would one determine this? ST47Talk 21:36, 7 December 2006 (UTC)

I'm unsure of what you mean by 'at a 90 degree angle' and 'lift the object up 45 degrees'. Can you clarify? -anonymous6494 22:24, 7 December 2006 (UTC)

I guess the arm of the crane is horizontal..

and lift the object so that the arm of the crane is at 45 degrees

I assume the crane arm is 65ft.

Need some more info. How big is the house and where in relation to the crane is the house.87.102.36.136 22:28, 7 December 2006 (UTC)

Retarded

How would it be possible to make a healthy intelligent individual retarded? Hit them in the head? Certain drugs? Lobotomy? Please advise ASAP thx. —The preceding unsigned comment was added by 128.61.113.155 (talk) 21:48, 7 December 2006 (UTC).

See Mental_retardation#Causes for information. Friday (talk) 22:14, 7 December 2006 (UTC)

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