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August 4

A question to Doctors.regarding my strainge chest pain.

All respected concerned health exeperts, would you please guide me the course of action I should take to takle my strainge pain which I am feeling for the last 4 to 5 days .I call it strainge as I AM QUITE NORMAL though at 66 of age my day to day activities are normal and Iam not experincing any kind of simptums other than this pain on the chest at right breast region.Pain is not consistant all through the day,I feel it when I sneege and or when I cough occasionally.If I sqeese the muscle on the breast Idont feel the pain but when I PRESS the right brest with my paw I feel the pain.Is it a impending heart problem ? Please adise me whether to ignore it as it might subside after few days or should I consult compintant Doctor.Iam male quite healthy at 66 of age except for slight hiper tension with reading 155 -86. I am vegitarian non smoker and active all through the day. Thank you yours loving s.k.pujar

There are many causes of chest pain. You should definitely see a doctor so that they can diagnose it. No one is going to be able to diagnose such a complicated thing well based on an online description, except to say, "It might be serious, go get it checked out." --Fastfission 03:11, 4 August 2006 (UTC)

You ask us Reference Desk editors to advise you whether to ignore your pain. Well, I advise you NOT TO IGNORE IT because we cannot give appropriate medical advice. A physician examining you can. Please do not hesitate to visit a doctor -- immediately if possible. --Ginkgo100 ^{talk · contribs · e@} 03:22, 4 August 2006 (UTC)

Of all of the chest pains that are seen, chest pain which is on the right side and you can reproduce by pressing the chest wall is least likely to be related to your heart. Especially after five days of constant pain without other symptoms. However, just because it might not be cardiac doesn't mean that it can't be something else just as bad. Please, go get it checked out as soon as possible! InvictaHOG 03:26, 4 August 2006 (UTC)

I agree. See a doctor immediately. StuRat 05:18, 4 August 2006 (UTC)

Et tu, StuRat? DirkvdM 07:27, 4 August 2006 (UTC)

"The fault is not within our stars, but within our editors." StuRat 06:57, 5 August 2006 (UTC)

car cell phone charger

Do car cell phone chargers convert dc from the car to ac which the phone can charge on?

Is it the reverse of one of those big, heavy wall adapters?

You're assuming those wall-adapter chargers are supplying AC... DMacks 04:04, 4 August 2006 (UTC)

All cell phones charge on DC. The wall adapters convert AC to DC; the car adapters convert DC to a lower voltage DC (the car voltage is ~28VDC, while most phones charge at less than 5VDC). However, the DC to DC converter can do it by first converting to a high-frequency AC and then back to DC (and, in the same way, the wall adapters can convert AC to DC to high-frequency AC to DC; this is usually done in the smaller wall adapters, while the big heavy ones use a large transformer and a direct AC to DC conversion). So, your car cell phone charger might be in fact converting to AC (but only as an intermediate step). --cesarb 16:46, 4 August 2006 (UTC)

28VDC? My car's voltage is around 14V when running. —Bradley 17:21, 4 August 2006 (UTC)

Car batteries are intended to supply around 12 volts. Most cars supply this voltage. 48v 18:13, 4 August 2006 (UTC)

(edit conflict) Looks like I confused the voltages. Indeed, cars use 12VDC nominal, not 24VDC nominal. --cesarb 18:16, 4 August 2006 (UTC)

http://www.dcacpowerinverters.com/

A friend of mine bought one of these, plugged it on one end into the car and on the other end into his regular wall cell phone charger. Is this wasteful/silly?

While this solution will work, yes. It is both wasteful and silly. The power which the car privides is very near the voltage which the phone needs to charge, the car chargers provide only a charging circuit and a voltage regulator. Instead he/she is using an inefficient 'inverter' to try to simulate AC residential power. And then using a moderately efficient chargere to convert that voltage (110-120) back to what the phone needs (5-10.) Buying a car charger would be cheaper, simpler, and better for the car battery. 48v 04:44, 6 August 2006 (UTC)

Hearing pianos over the phone

Why can't you hear pianos clearly over cellphones? This problem doesn't appear to exist with other instruments, the guitar for example. Any ideas? Please answer on my talk page. Thanks for your help! MarkBuckles (talk) 04:49, 4 August 2006 (UTC)

I would guess it's the small frequency range on each piano note. They may fall into "frequency holes", which are omitted to fit more conversations into a given bandwidth in a highly compressed cell phone transmission. StuRat 05:14, 4 August 2006 (UTC)

Piano notes have a small frequency range? Most keys hit more than one string and they're in an encasing that gives them ample opportunity to give off all possible vibrations, resulting in many overtones. On top of that, the piano is the instrument with the widest tone-range. A telephone line is, however, restricted to the frequencies that are important for speech. Piano key frequencies range from 27 to over 4000 Hz. The range of the guitar is from 82 to less than 1000 Hz (way up on the neck). I can't find what frequencies are transmitted over a telephone (searching for 'telephone frequencies' only leads to radio frequencies the connections use, which is something different). But it may be in the hundreds of Hz (althogh I thought it was around 1000 Hz), which would explain why you can't hear notes above that. You could still hear lower notes, though, through the overtones. So same answer, just the other way around. :) DirkvdM 07:59, 4 August 2006 (UTC).

The standard sampling rate for telephony is 8000Hz, which due to the Nyquist–Shannon theorem means the highest frequency transmitted is 4000Hz (see Nyquist rate). If you use 8 bits per sample, you have a bitrate of exactly 64000 bit/s, which uses too much radio bandwidth (on POTS, however, you have almost the full 64000bps rate). To reduce the bandwidth, the sound is compressed using special speech codecs (which can vary from 13kbit/s to as low as 4.75 kbit/s). Of course, to reduce the data rate that much, some information is lost; these codecs are optimized to retain more information related to the human voice (and, sometimes out-of-band, DTMF tones), and less information related to everything else (including background noise and music; comfort noise can also be generated at the receiver). It's not a specific frequency being dropped (i.e. there are no "frequency holes"); these codecs actually try to predict the waveform using mathematical models (tuned to the human voice), and encode the resulting coefficients and residuals. --cesarb 16:22, 4 August 2006 (UTC)

So the explanation would be that (somehow) a guitar behaves more like a human voice? Might be interresting to test how different instruments and different notes on those instruments come across on a telephone. i just don't know who I might call who would be equally interrested in such an experiment. Ah come on, do I really have no interresting friends? Is that why I spend so much time here? Or is that the other way around? ... I will now just go and sit in a corner and feel sorry for myself. DirkvdM 19:04, 4 August 2006 (UTC)

You could try to find implementations of these codecs which run on a normal PC, convert a small sample of music (losslessly compressed if possible) to the codec and back to a normal wave file, and then do a blind a/b test (we seem to be missing either an article or a redirect here; any takers?). --cesarb 23:43, 4 August 2006 (UTC)

We do have Speex, ABX, Codec listening test, and double-blind test. --Kjoonlee 08:29, 6 August 2006 (UTC)

Part of the characterist sound of a piano is not the sustained tone alone, composed of a fundamental plus harmonics, but the initial attack as the key is struck. The 300 or 400 Hz high frequency cutoff in modern phones may allow the fundamental tones to pass, but block some of the harmonics. It may also cut off some of the envelope of the initial attack, which is somewhat percussive and may include more high frequencies. Edison 18:24, 5 August 2006 (UTC)

There's a high frequency cutoff at just a few hundred Hz? That explains a lot. If you're sure about this, could you add it to the telephone article? DirkvdM 08:50, 6 August 2006 (UTC)

No way it could be that low; plain lowpassing at 500 Hz gives an awful muffled sound with all sibilants unintelligible. --Kjoonlee 09:08, 6 August 2006 (UTC)

I assume Edison meant 4000 Hz, as cesarb mentioned above. --Kjoonlee 09:09, 6 August 2006 (UTC)

exhausting a portable air conditioner through the chimney flue

Is it possible to exhaust a portable air conditioner's exhaust through the chimney flue instead of the window? Would I be able to force the air out with a fan (after closing a furnace exhust vent) if the atmospheric pressure is too great?

Maybe. As you seem to already know, the exhaust from the A/C unit won't be sufficient in volume or heat to create a proper draft up the chimney. A fan at the chimney alone probably wouldn't be sufficient, either, as this would create a negative pressure in the house sucking the exhaust back down the chimney. If a second fan were added to force air into the house, this would probably do the trick. However, this would be blowing in hot air from outside which is going to fight the A/C unit. I suppose it still might cool the room containing the A/C unit, but the room in which the air enters the house would get hot. So, I recommend against this approach. Now, if you could rig up a long tube and route it up the chimney, and force the exhaust up the tube, that might work a lot better. A dryer vent hose might work. StuRat 05:08, 4 August 2006 (UTC)

Our toilet has such a ventilation shaft with a fan, so it should work. Air will easily get sucked in through all sorts of holes and chinks (is that the right word?) in the house. If it's hot and you create a lot of current that would be like having a fan for the whole house, so you can leave the ac off. It would have to be pretty strong, though. But then you wouldn't need the ac, which is begging the question. I suppose you'd better ignore this advise. DirkvdM 08:11, 4 August 2006 (UTC)

Of course, indoor Cannabis growers do this all the time. AllanHainey 14:46, 4 August 2006 (UTC)

I don't. I like the smell. DirkvdM 19:06, 4 August 2006 (UTC)

Every portable AC that I've had also drips water out the back. If you try to put it in a chimney opening, you'll end up with a puddle in your chimney. --Kainaw ^(talk) 14:48, 4 August 2006 (UTC)

The air conditioner doesn't really exhaust air; it exhausts heat. The fan on the hot side of an air conditioner is only there to increase the heat transfer not get rid of air. So, a single fan in the chimney would do very little as you need to be pulling cooler air into the condensing coils of the air conditioner. StuRat's idea of a tube within the chimney (a tube within a tube, effectively) to pull down cooler air and push out hotter air would be best. Modern wood-burning stoves do this. They pull the combustion air down the outside of a double-walled stack, burn the wood, and the combustion gases are vented up the middle of the stack. This prevents the stove from stealing your warm air in the house for combustion and pushing it out the chimney. In this case, you don't want the air conditioner stealing your cooled air to cool the condensor coil and push it out the chimney. —Bradley 17:16, 4 August 2006 (UTC)

Meteorite

Is it possible that a meteorite could hit the earth at an angle that would forever increase the speed at which our planet rotates on its axis. Thanks.

Sure, but not by a lot. Something the size of what killed the dinosaurs could change the angular velocity of the Earth by up to about a few milliseconds per day. Dragons flight 05:29, 4 August 2006 (UTC)

Just consider classical physics questions of momentum--the metorite would have to have a combination of mass*velocity (useful to visualize as a vector) that was non-negligable to the mass*velocity vector of the earth in order to detectably alter the earth's vector. I'd be more worried about massive global extinctions over resetting my Timex if something that large were to come our way... -- Scientizzle 07:45, 4 August 2006 (UTC)

Let's fill this in. Earth's volume is 10¹² km³. A really really big meteorite could be 10x10x10 km = 10³ km³. Assuming the same mass per volume, that would mean the meteorite's mass is only one billionth of Earth's. Earth has a rotational velocity of 465 m/s at the equator. Compensating for the fact that not all mass is at the surface, let's say 100 m/s. If the meteorite had 1000 times that speed (100,000 m/s or 360,000 km/hr - an enormous speed) then that would only constitute 1 millionth of Earth's rotational momentum. Also, just a tiny fraction would go into a rotational change - most of the energy would be absorbed (on this scale the Earth is quite elastic) and of the remaining energy, most will change the Earth's direction (and thus its orbit), not it's rotation, depending on the angle at which it hits. And that change would also be minute. DirkvdM 08:26, 4 August 2006 (UTC)

Let's just make some assumptions to simplify things here. a) Assume all the momentum transfered from the meteorite to the Earth is transfered to the Earth's angular momentum about the centre of mass (it hits a cliff). b) Assume the collision is perfectly elastic.
The angular momentum of a sphere is given by $(2/5)MR^{2}$ (the moment of inertia) multiplied by the angular velocity. For the Earth this works (I think) at about 2.5x10⁵⁷. I'll leave you to come up with momenta for meteorites.
As DirkvdM says, in reality most of the momentum would be affecting the angular momentum of Earth's centre of mass (it's orbit), but as this is so much higher than the angular momentum about the centre of mass I would guess that (depending on the angle of collision) there would be a greater effect on the Earth's rotation (about its axis) than on its orbit.

What about a really really really big meteorite... But then again you might prefer to call a Mars-sized rock a "planetary collision" rather than a "meteorite hit". Weregerbil 09:46, 4 August 2006 (UTC)

One possible explanation for how the moon formed is as a result of a giant meteor collision with Earth. A meteor this size would likely have affected the rotation rate of the Earth by a significant amount. StuRat 07:45, 5 August 2006 (UTC)

Based on what StuRat said I'm not sure if it actually affected it's rotation but the metorite which hit the earth actually put the earth on a rotation (thus giving us the seasons). However, i think it can be possible if a metorite that large hit the earth and was that large could affect it's rotation speed. Probably much like the Metorite Apophis

--Agester 20:37, 10 August 2006 (UTC)

Some corrections are needed here. The seasons are caused by the Earth's tilt and revolution around the Sun, not by it's rotation. The rotation only causes day and night. Also, the Earth would have had an initial rotation, which comes from the rotation of the solar system. According to physics, as the diameter of a rotating object decreases, it spins faster to maintain a constant rotational momentum. Thus, as the Earth formed from a dust cloud, the rotation of the cloud would increase. I would think we could calculate the expected rotation rate of a planet based on it's size and distance from the Sun. Then, any deviation from the expected value would be from impacts since then (most of which might be tiny dust particles hitting the atmosphere). StuRat 17:46, 11 August 2006 (UTC)

Bullet

If I fired a bullet stright up into the air would it (technically) hit the ground at the same speed that it left the gun from. Assuming there is no wind etc.

Not likely, since most bullets are fired at speeds beyond terminal velocity. -- Scientizzle 07:29, 4 August 2006 (UTC)

If fired in a vacuum, however, it would. When dealing with speeds that don't approach the terminal velocity of the object in question, it's safe to say that upward release velocity will be essentially equal to downward falling velocity at the same height (with variations due to chaotic perturbations of the air and object, etc.). The nature of an atmosphere that provides non-negligable friction makes things slightly more complicated at higher velocities... -- Scientizzle 07:38, 4 August 2006 (UTC)

Don't try this at home. And if you do it outside, make sure to step aside. DirkvdM 08:30, 4 August 2006 (UTC)

See also MythBusters (season 3), Episode 50. It seems that if the bullet retains its spin, it will exceed its normal terminal velocity.--Shantavira 11:56, 4 August 2006 (UTC)

They also pointed out that the bullet would retain spin if it had any arc in the path. To keep it from spinning, you have to fire it straight up - which is nearly impossible to do. The gun, wind, spin of the Earth, and all will contribute to causing the bullet to go up at an angle, arc over (still spinning), and come back down.

Answering the question, though - no. It will not be at the same speed. Bullets do slow down as they pass through the air. Even though it will still be a lethal speed, it will be slower than the muzzle velocity. --Kainaw ^(talk) 13:30, 4 August 2006 (UTC)

The only real factor that would cause the bullet to have a different speed would be air resistance. Firing the gun from the surface of the Earth, it would be nearly impossible to get it to move in anything other than an arc due to the coriolis force caused by the Earth's rotation (which wouldn't be very much unless it was a very very powerful gun). This shouldn't effect its speed when it lands though as it wont travel any further coming down than it would going up. It's all about conservation of energy.
Mathematically, the velocity with which it would hit the ground would look something like:$v=u-((2Du+2Dd)/2)$½ where v is the final velocity, u is the initial velocity and D_u and D_d are the energy losses on the ascent and decent respectively.

If he stood on the equator of the moon, facing in the direction of the moon's rotation and fired his pistol straight up (so no air resistance) at 300 m/s, would it go straight up and come straight down and (theoretically) land in the barrel of the pistol? The gun rotates with the moon surface at 4.63 m/s in a slightly curved path. The bullet along with its decelerating vertical velocity has an initial horizontal velocity of 4.63 m/s. At the moon's gravity of 1.622 m/sec squared, the bullet would rise for 185 seconds to its highest point. It would fall for another 185 seconds. If the shooter could see it, it would appear to move along the equator retrograde to the direction of rotation, and would land to the retrograde side of the gun. Not good enough at orbital mechanics to say exactly how far behind, but I am curious. Then assume he stood on the north pole of the moon and repeated the experiment. The coriolis effect due to the moon's rotation should be absent, but what effect would the orbital velocity of the moon about the earth and about the sun have?Edison 19:35, 5 August 2006 (UTC)

If he stood on the equator and fired the gun the bullet would land in front of him (doing a quick calculation) as the coriolis force causing the bullet to land in front of the firing point would have a greater effect than the rotation of the Moon causing the bullet to land behind the gun.
Taking the Coriolis force as F = 2mΩv you can calculate that the distance moved in the direction of rotation is (4Ωu²)/g and the (apparant) distance moved in the opposite direction is (2uΩ)/g you can see that it will always move further in the direction of rotation.
Standing on one of the poles, the effects of the Moon orbiting the Earth and the Earth orbiting the Sun would stop the bullet landing back down the barrel of the gun, but they shouldn't have a great effect (if you don't fire the bullet too high).

Energy consumption per country

We've got lists on just about anything, but I can't find a list showing the energy consumption per capita per country. All I can find is Image:Energyconsumption.jpg and Image:Energy per capita.png, but those don't show what I am looking for and only give vague indications. The latter has a list it's based on plus a source, but before I make that into an article I want to be sure there isn't already such a list (in a less obvious place perhaps) and also that I can use (and re-arrage) the data (no copyright violation). DirkvdM 08:50, 4 August 2006 (UTC)

Since you participated in the discussion, I assume you've seen of List of countries by electricity consumption, right? There is also List of countries by natural gas consumption. I don't think we have one on total energy consumption, which would be cool, although I'm not sure how it would be defined. --Bmk 15:35, 4 August 2006 (UTC)

When I worked in energy conservation 30 years ago, we we able to find figures for the "quads" of total energy used by the US and other countries. It should be easier now with the internet, but maybe you should visit a good sized library and have the librarian direct you to reference books on energy. We had a very small proportion of the earth's population and used a very large portion of the energy. Have things changed much? I don't think so, except that there are decreasing reserves of oil and increasing demand in developing nations. Don't forget to combine all sources of energy, and to allocate electricity to end users.Edison 19:40, 5 August 2006 (UTC)

Birds in Slovenia

Why are apparently very few birds in Slovenia. On a holiday in the region of Lake Bohinj, it was noticed that there was no dawn chorus, and few visible birds. Why is this? Thanks, --217.42.132.207 09:38, 4 August 2006 (UTC)

I believe this is because people take pot-shots at them for sport. It's much the same in many parts of eastern and southern Europe. One side effect is that butterflies etc flourish in places like this.--Shantavira 11:53, 4 August 2006 (UTC)

The same thing happens in Italy, people shoot them for food & sport when they migrate over & large numbers don't make it. There was a BBC Radio 4 programme on several months ago about this and the steps being taken to try to preserve the birds, such as legislation & bird reserves. I don't think that there has been a great deal of success in stopping the hunters. AllanHainey 14:28, 4 August 2006 (UTC)

Overhunting led to the extinction of the carrier pigeon. User:Zoe|(talk) 22:38, 5 August 2006 (UTC)

HD-DVD or Blu-Ray

At this point, which standard seems more likely to be adopted as the primary for consumers and studios?

I can't remember which way round it is, but one is supported by Apple and the other by Microsoft. I'd plumb for the one supported by Apple.

Really, we don't know. It is whatever hits The Tipping Point first. They both have their pros and cons. Sony is supporting Blu-Ray all the way, they already are putting out movies in DVD and Blu-Ray. If you just looked at the names, and they were the same thing, you would pick Blu-Ray. I've found I personally, and most people, like technology names to be less abstract. They prefer Mac OS Tiger, or Lisa over AOL version 10.2.3, or Microsoft XP SP3. — [Mac Davis] (talk)

I am holding out until Blu-Ray 2.0, then, just to be contrary!

Weird really. The whole point of the free market system and competing companies and technologies is that the consumers pick the ones they like so those manufacturers get an impulse to make more such products. Sounds good in theory, but in this case consumers just sit around waiting for which one will become the standard and only then go out and buy it. Which is the wrong way around. The central problem here is that the determining factor is the standard. So that should really be set by others, after which the manufacturers can then all use this open (!) standard and start competing with actual products. The openness of the standard is essential for this (the free market really works on the wrong level here). So who should set that then? The old answer would have been governments. But the new answer is the Open Source community. Any ideas how this could be brought about? Is it just a matter of some people deciding to come up with a standard and then presenting that to manufacturers? Or do the consumers need to be convinced to go for that one? DirkvdM 19:24, 4 August 2006 (UTC)

I don't know much about blu-ray/hddvd, but isn't it a fundamental hardware difference? How can open-source communities handle this? If it were up to open-source folks, there would be 10 different versions of the new DVD instead of two.

As a consumer, I don't really care about blu-ray or hddvd, I just want to consume video at a reasonable quality and reasonable availableness for the cheapest price possible. I don't want to invest and put in some mighty dollar votes for the newest gadgets. It's a means to an end and that's all.

The link you want is dollar voting. Make sure to also check out the talk page.

The open source community would converge on one standard. If you're thinking about the many Linux distros, that's exactly what I mean. There are many distros, but they all use the same Linux core. That's the standard. Commercial companies (and others) can then use that for their own version, thus putting the competition where it should be, but leaving the standard alone. DirkvdM 09:09, 5 August 2006 (UTC)

All the latest talk is about how HD-DVD is better in quality, and the players are 1/2 the price of a bluray. Given Sony's hysterical failings of making new standards I seriously don't see how they will ever succeed --mboverload@ 00:45, 5 August 2006 (UTC)

It's possible - perhaps likely - that the true successor to DVDs will be neither Blu-Ray nor HD-DVD, but instead will be online file-transfer, scrapping physical media altogether. The current competition between Blu-Ray and HD will hold everything up a long time, where as digital files have many more benefits to producers (there's essentially no cost to creating a new file, and if they use something like BitTorrent to distribute it, bandwith costs fall on consumers). In short - the average person shouldn't bother getting either Blu-Ray and HD-DVD for a long time, if ever. zafiroblue05 | Talk 01:13, 5 August 2006 (UTC)

The dirty truth is that we might not even need a new format. A movie encoded with H.264 or similar advanced codec can fit an HD movie on a standard DVD. In fact I have The Transporter in 720p HD in only 4 gigs, while standard movie dvds are 8. --mboverload@ 07:08, 5 August 2006 (UTC)

I'd like a new format, I will always think it's a good idea to back up my hard-drive on a read-only disc. And my hard-drive can only get bigger in the future.

priming fuel pumps

i wonder why internal combustion engines use centrifugal pumps for the fuel delivery system.this gives us the headaches of priming the pumps.isnt it possible just to use a positive displacement pump for fuel delivery since it needs no priming?why prefering the centrifugal ones.moreover i understand centrifugal pumps do not develop good pressure heads. --Chiwaye 13:48, 4 August 2006 (UTC)Chiwaye,04/08/06

Rabbit Internal Organs

Hello,

Can someone tell me what the, relatively, large white organ rabbits have, I've ruled out the heart, stomach & I think kidneys but I've no idea what it is. It's white with a few red flecks or thin veins & its ovalish. Any ideas? AllanHainey 14:22, 4 August 2006 (UTC)

The liver? --Ginkgo100 ^{talk · contribs · e@} 14:32, 4 August 2006 (UTC)

A bladder shall be whiter than a liver. --DLL 15:21, 4 August 2006 (UTC)

Rabbits have a pretty big cecum, which kind of matches your description. Is it a hollow organ? --Joelmills 15:43, 4 August 2006 (UTC)

I didn't cut it open to see but it may be the cecum. Sounds like either the Cecum or bladder. Thanks. AllanHainey 07:22, 7 August 2006 (UTC)

Do you have a picture? The location in the body may give us a clue. - Cybergoth 20:37, 14 August 2006 (UTC)

lichen damage to trees

Can lichen, growing on the bark of trees, damage the trees? I have a Wigelia (tree form)that is covered with lichen and one branch has become so soft that it has twisted and flopped to the ground.

Thanks to everyone for any help you can give me. Antcathy

I wouldn't think so. Are you sure it's lichen ? StuRat 05:45, 6 August 2006 (UTC)

Oldest surviving sound recordings

Dear Wikipedia, I have tried searching on wikipedia for the oldest surviving sound recordings. Wikipedia provides a video file of the 'Roundhay Garden Scene' (1888); supposedly the oldest motion picture and also provides the oldest surviving photograph; 'View from the study window' (1826/27) by Niepce (I think that's how you spell his name). Wikipedia doesn't, however, seem to provide the world's oldest surviving sound recordings. I wrote to the British Library a while ago to find out more. Here is a copy of my question and their answer...

'Hello, my name's Russell and I may have an FAQ for you. I am interested in finding the world's oldest surviving sound recording.

I've heard that the first thing ever recored was Edison's 'Mary had a little lamb' from Decemeber 1877 but presumably this does not still exist.

I've tried searching on the Internet but can't seem to find out. If you could help I'd be grateful.

Kind regards, Russell.'

'Dear Russell,

Thanks for your enquiry. The earliest surviving recordings appear to date from 1888. For spoken word it is allegedly Lord Stanley's address in Toronto, see here http://radio.cbc.ca/programs/thismorning/lfnsound/sound_collectors/sound_collectors_092000.html. For music it is allegedly a recording of Handel's choral music http://www.nps.gov/edis/edisonia/very_early.htm . However, the recording on the following site can claim to be the oldest playable recording http://www.tinfoil.com/cm-0101.htm.

I hope this helps.

Yours sincerely,

Rod Hamilton

Reference Specialist (Sound Archive) Humanities Reference Service The British Library 96 Euston Road London NW1 2DB UK Email: <e-mail removed to prevent spam> Tel: +44 (0)20 7412 7676

I am no expert so I'm a little dubious about writing an article.

Thanks for doing the research! Sometimes on Wikipedia, in order to avoid knighting a thing as "the oldest X" where there is uncertainty or disagreement, we'll have a list of candidates. Then, if a candidate has an article, its claim to the title is linked to the list. Examples can be found in Category:World records. Perhaps it's time for an Oldest sound recording article, with a section for surviving recordings? Melchoir 20:08, 4 August 2006 (UTC)

I think you mean "dubbing", Melchoir. "Dubbed" can be applied to naming things generally, including making a man a knight. But "knighted" can only be used in that specific sense. JackofOz 12:34, 8 August 2006 (UTC)

If you want some historic wax in your ears try Tennyson's 1890 recording of The Charge of the Light Brigade or Robert Browning's How They Brought the Good News from Ghent to Aix from 1889. MeltBanana 23:11, 4 August 2006 (UTC)

I've heard Edison reciting Mary Had a Little Lamb, so some version of this recording still exists. StuRat 07:35, 5 August 2006 (UTC)

Someone was clever enough to make a backup? Ehm, ... on what? DirkvdM 09:12, 5 August 2006 (UTC)

Naw it was a hysterical re-enactment [1] MeltBanana 14:01, 5 August 2006 (UTC)

Edison's first phonograph was demonstrated to Scientific American editors in their offices and featured in the December 22, 1877 issue. IIRC, they included an illustration supposed to be an exact representation of a photo of the pattern of indentation in a tinfoil recording. That photograph or to a less accurate degree the illistration published would theoretically be one of the oldest "surviving" recordings. Actual foils are supposed to be too fragile to play, but a laser scan of one might produce reproducible sounds. A month or so later, tin the multi-volume collected papers of Edison, one of his assistants wrote he had made a plaster impression of a tinfoil recording which accurately reproduced all the indentations, and that he thought copies could be made from it. There is no sign this was done at the time, but maybe it is in a file somewhere. The phonautograph was pre-Edison and made accurate sound tracings on smoked glass cylinders. In fiction, they have been copied and played and perhaps could be in reality. There are urban legends of ancient pottery turned on a wheel and decorated with a wooden stylus having accidentally recorded sounds in the pottery shop, but the potter's hand would be far less effective than Edison's diaphragm connected to a recording stylus as a sound collector. Edison 19:59, 5 August 2006 (UTC)

about macbook (screen size 13.3 inches)

Have anyone seen the new mac book from apple which has a screen size of 13.3 inches? Is it big enough for anyone? Or is it just for students aged under 18? Is it good enough for adults? One more thing I would like to know What is the ideal distance between this monitor and our eyes while reading?

Thanks

I personally find that the bigger the screen, the better, because quality is not an issue with MacBook screens. I think if you're not a college kid without any money, you should get a bigger screen. I just checked the site, [2], and it says 13.3 is the only size for MacBooks!! I guess if you want a bigger screen you'll have to get a Pro. As for ideal monitor-eye distance, it is like the whole "don't sit too close to the tv Timmy, you'll hurt your eyes." You put your eyes where ever it is easiest for you to read. — [Mac Davis] (talk)

I think one good thing to check about a screen/computer combination is the refresh rate - try opening a window, then dragging it around the screen very quickly - if the motion looks choppy, you might want to look elsewhere. --Bmk 18:14, 4 August 2006 (UTC)

Just to get all pedantic on you, it's an LCD screen, so it doesn't have a refresh rate: it has a pixel response time. - Nunh-huh 04:32, 5 August 2006 (UTC)

Thanks for making time for that refreshing response. :-) StuRat 07:31, 5 August 2006 (UTC)

Screen size in laptops is usually directly correlated with weight. If you plan to carry this around with you a lot, a smaller size can make a lot of difference (I use a 12" iBook for this reason, it is large enough for everything I use it for). But if you have doubts you should go to an Apple retail store, where they will no doubt have many display units out that you can play with and see.--Fastfission 18:26, 4 August 2006 (UTC)

It really depends on what you're doing. When I'm programming, I find the 17-inch display on my laptop to be too small, but for reading ebooks, the 2.5-inch screen on my PDA is just fine. --67.185.172.158 04:23, 5 August 2006 (UTC)

Resolution is most of it for me, I had been using a 19xx by 16xx resolution for a while I think, I came back home, got on my old iMac, with a 1280x800 resolution, and everything seemed so fat. lol — [Mac Davis] (talk)

Freaky Plant Situation

Is it possible for two plants to get fused together or exchange genetic material just by being planted very close together? Because I have two plants, a green one and a purple one, and recently the greeen one's been getting streaks of purple in the leaves. The purple plant has vine-like stems and now the green plant is growing vines and it never did before. I have no idea what type of plants they are. It's sort of freaky, but I swear it's absolutely true. Is it possible the purple plant's a parasite or something? --Anakata 22:05, 4 August 2006 (UTC)

Also, another thing is that one of the abnormal vines on the green plant is actually growing through one of its own leaves, i.e. it poked a hole through it.--Anakata 22:14, 4 August 2006 (UTC)

There's something that sounds similar: see Chimera (plant) and Graft-chimaera. Melchoir 22:46, 4 August 2006 (UTC)

The Chimera thing could be the cause, but these strange purple streaks only started appearing very recently, like one month ago. Before that the plant was perfectly fine and green throughout. If it was a chimera, wouldn't it be like this from the start?--Anakata 23:02, 4 August 2006 (UTC)

Can you upload a photo? —Keenan Pepper 23:04, 4 August 2006 (UTC)

Are the two plants of the same species, and do the reproduce sexually (via stamen, pistols, and pollen) ? If so you may get a cross pollination between the two color phases. I've seen this in alyssum myself. StuRat 07:24, 5 August 2006 (UTC)

If the colouring is caused by some chemical, there need not be an exchange of genetic material, just picking up some of the other's juices. Just a guess DirkvdM 09:16, 5 August 2006 (UTC)

Reproductivity of results

What is meant by reproducibility of results in science? Why is this important in science?

--anonymous. —The preceding unsigned comment was added by 70.233.162.76 (talk • contribs) .

Never mind:)

ανωνυμία —The preceding unsigned comment was added by 70.233.162.76 (talk • contribs) .

August 5

You can't make a silk purse out of a sow's ear

Some time ago, I heard about a group of researchers at a university extracting a substance strongly resembling silk from pigs' ears, and using it to make a purse. However, I can't find anything about this besides retellings of the story, with various embellishments. Is there any truth to this, or is it another urban legend? --67.185.172.158 04:20, 5 August 2006 (UTC)

I read something like that many years ago. Googled "silk purse" "sow ear" et voila: Arthur D. Little, who studied chemistry at MIT in the 1880's and founded a large consulting firm. He did it in 1921: http://libraries.mit.edu/archives/exhibits/purse/index.html and http://historywired.si.edu/object.cfm?ID=535 Edison 20:09, 5 August 2006 (UTC)

Tails of shrimp, stems of peperoncini, and peels of oranges and banannas

People often think I am some kind of weirdo because I eat the tails of shrimp, stems of peperoncini, and the peels of oranges.

I sortof understand from a taste/texture point of view - shrip tails are really crunchy and hard to eat, peperoncini stems are stringy, and orange/bananna peels are just bitter.

Are any of them bad for you, though? Is it really that weird to eat these things? It just comes from a family where, if you have food, you EAT it. --69.138.61.168 05:12, 5 August 2006 (UTC)

Nope. I've visited parts of the word where these things are considered delicacies - of course, they are prepared differently than what I imagine a typical Wikipedian would. --HappyCamper 05:15, 5 August 2006 (UTC)

One thing to watch out for is that orange peels may have pesticides and dyes in them that are not intended for human consumption. So, you'd better stick with organic oranges if you intend to eat the peels. StuRat 07:19, 5 August 2006 (UTC)

And in the tropics it is often advised to only eat peeled fruit (and to peel it yourself) to avoid diseases. Don't know which ones, though. DirkvdM 09:20, 5 August 2006 (UTC)

Obelix once complained of his belly after eating oysters. Asterix asked him "Don't you take off the shells ?" --DLL 17:19, 6 August 2006 (UTC)

i ned an urgent info

dear sir, i need an urgent info how to separate UREA and CREATININ from a water solution?

please get me the details in this regards as soon as poissible. thanks.. with regards, budhaditya chattopadhyay, bangalore, india BE(medical electronics) <email address removed>

depends on what purpose they need to be seperated for. if you just want to seperate them analytically, i'm sure RP-HPLC will do the trick. If you want to seperate them preperatively, it becomes more tricky. perhaps cation exchange chromatography? you could exploit the charge differences, i imagine creatinine picks up a positive charge at a higher pH than urea. from a quick look, it seems creatinine forms a complex with zinc chloride, you could have a go at that. Xcomradex 07:44, 5 August 2006 (UTC)

Windows Vista

I think I once saw a link to a program (on Wikipedia) that would configure an XP computer to take on the appearance of a Vista-driven one. Does such a program exist?--the ninth bright shiner ^talk 05:56, 5 August 2006 (UTC)

Maybe this helps? [3] --Abdull 10:06, 5 August 2006 (UTC)

possible infant diarrhea epidemic in Detroit's Harper Hospital in 1943

My infant brother died of diarrhea that year and the family story was that many babies died of it at Harper Hospital during the time of the 1943 race riots because they could not separate the well babies from the sick babies during the riot. I recall at one time years ago reading a newspaper clipping about it but cannot find any now. I am a retired reference librarian so I've looked pretty hard under subject headings pertaining to the (1)riots,(2)Harper's history and(3)medicine, but I know the databases are very different today. Thank you. --209.112.212.40 06:12, 5 August 2006 (UTC)

I don't have an answer, but would like to point out that diarrhea isn't a disease, but rather a symptom of many diseases, quite a few of which result from poor sanitation, especially drinking dirty water. It would be important to know the actual disease which caused the fatal diarrhea if you wanted to research it more thoroughly. Also note that simple rehydration therapy (drinking fluids somewhat similar in composition to Gatorade) can prevent death from diarrhea, so I would research whether this was done at that hospital at that time. StuRat 07:10, 5 August 2006 (UTC)

If I had to guess a disease that would cause an epidemic of diarrhea affecting infants in a hospital, I would tend to assume either cholera or amoebic dysentery. Our article on diarrhea discusses these and more. --ByeByeBaby 13:36, 7 August 2006 (UTC)

As a relative you should be able to get a copy of the death certificate which should list the exact cause. (in 1940s terminology.) Rmhermen 00:18, 9 August 2006 (UTC)

I've been quite disappointed with death certificates. They frequently just seem to take a guess at the cause, or just list a symptom. It probably just lists "diarrhea" as the cause of death, or maybe "dehydration". Considering that resources are allocated based on the fatality rates of various diseases, it doesn't seem right that death certs are so sloppy in listing the cause of death. StuRat 22:10, 9 August 2006 (UTC)

Chromatography

SIR, I am not able to understand the basic concept of chromatography hence i am fasing problem to learn and understand it.

1) For, eg. " In chromatography , the sample is applied at one end of the porous support which holds the stationary phase and the mobile phase is made to flow over it". The various constituents in the sample gets seperated due to difference in their distribution behaviour.

Now, the stationary phase is the porous support or the sample which is applied? What it is ment by distribution behaviour?

2) The various chromatographic techniques can be classified depanding upon the forces of interacting phenomenon between the solute molecules and the stationary phase.

Now which is the solute molecule and whice is stationary phase, Can you give me any example.

3) Can you explain me the principle of gel- filtration chromatography in simple english.

Thank you. —The preceding unsigned comment was added by Jimitshah123 (talk • contribs) .

I changed the formatting to make your questions easier to read. What are you quoting here? It's not the article Chromatography. Maybe you should start by reading that. —Keenan Pepper 06:32, 5 August 2006 (UTC)

The "simple English" WP has no Chromatography article. Imagine what concepts could be operated to deliver something readable for one only acquainted with simple words (but shall such words be enough when it comes to facing the study of a "problem".) There ought to be a ferryman and it should be the teacher : Why don't they get asked first ? --DLL 17:13, 6 August 2006 (UTC)

atomic physcis

which has higher energy the nuclear fusion or nuclear fission?

nuclear fusion + nuclear fission. Have fun with your homework =D --mboverload@ 06:59, 5 August 2006 (UTC)

Fission and fusion are processes that convert energy from one form into another. It doesn't make sense to say they "have energy". Atomic nuclei have different amounts of energy, as shown in Image:AvgBindingEnergyPerNucleon.jpg, and that's what makes fission and fusion possible. —Keenan Pepper 07:14, 5 August 2006 (UTC)

Fusion generally releases more energy. This is what you should write down. — [Mac Davis] (talk)

...that is, fusion of a given mass generally releases more energy than fission of an identical mass. Fusion also requires much more energy to initiate. StuRat 20:32, 5 August 2006 (UTC)

Since when do we just tell people what to write down?? —Keenan Pepper 05:14, 6 August 2006 (UTC)

Beware that they don't write down you name too. The parents might sue you if the pupil gets convinced of obtaining extra help. --DLL 17:06, 6 August 2006 (UTC)

Three times the same optical phenomenon?

What are the differences between anthelia, glory (optical phenomenon) and heiligenschein? --Abdull 10:04, 5 August 2006 (UTC)

Well spotted. I'm pretty sure these are the same phenomenon. The articles need to be merged (anyone?). Anthelia is the plural, by the way, and duplicates anthelion.--Shantavira 15:30, 5 August 2006 (UTC)

go ahead and merge it abdull. be bold

Actually, sudden mergers can upset some people. It might be wiser to apply {{mergeto}} and {{mergefrom}} and see who rises to comment. Melchoir 17:05, 5 August 2006 (UTC)

It looks to me as though "anathelia" and "glory" should be merged, but "heiligenschein" is different (for example, it doesn't seem to have rainbow colors). --Trovatore 05:39, 6 August 2006 (UTC)

I redirected anthelion and anthelia into glory (optical phenomenon) without merging. Heiligenschein needs a little bit more work, since the glory article needs to note that the phenomenon can occur on dewy grass. Gdr 11:52, 6 August 2006 (UTC)

But the point is, I think it's a different phenomenon on the dewey grass, since you don't see rainbow bands of color, just white. --Trovatore 17:09, 6 August 2006 (UTC)

Yes, it's a different phenomenon altogether. If you follow one of the external links from heiligenschein you'll see that the explanation has to do with the drops of water focusing the sunlight on the blade of grass behind them, then acting as a lens from the point of view of the viewer. A glory, on the other hand, has to do with surface waves of light on the water drop itself. So please don't merge these; they seem to be quite distinct. --Trovatore 17:30, 6 August 2006 (UTC)

The other side of the Big Bank

After the Big Bang, why is it that the Universe is expanding in one general direction? If this is not the case, then what is on the other side of the initial point of the Big Bang?

--Dparisi 16:38, 5 August 2006 (UTC)

In one general direction? It expands forward in time. If it expands backward in time from its starting point, I don't think we'd know. In most (all?) big bang scenarios, time started at the initial point and so nothing was before it because there was no time before it. digfarenough (talk) 16:53, 5 August 2006 (UTC)

In some branches of String Theory it is possible that there was a 'before the big bang'.

I think that Dparisi is under the impression that the universe is moving out into the left (or right). In reality, because the universe itself is expanding (not a bunch of things moving away into the universe), it makes no sense to say that it is expanding in a direction. Space is just getting bigger. —Daniel (‽) 17:39, 5 August 2006 (UTC)

One way to visualise this is as a balloon with dots on it. When you blow up the balloon, all the dots move away from each other. We observe (almost) all stars around us moving away from us, so the conclusion was that we must be part of an 'expanding balloon', ie the universe is expanding. Of course one flaw here is that you can see that the balloon is expanding in relation to its surroundings (the other option would be that everything else is getting smaller, which would be silly). But the universe is everything, so what do you measure its size against? Don't we have to assume that the size of the universe is fixed? (if it indeed is everything) DirkvdM 17:48, 5 August 2006 (UTC)

It is usual to say that all the galaxies in the Universe are moving away from us as opposed to most stars (although as all the stars in the Universe apart from the ones in our galaxy are moving away from us). The balloon analogy can be better expressed by affixing coins to the balloon (top represent galaxies) as these wont expand with the expansion of the balloon. The only real problem with the balloon analogy is that the curvature of a balloon is positive and the curvature of the Universe is zero. This analogy is useful for demonstrating that the big bang happened both everywhere and nowhere.
We measure the size of the Universe from the inside by using standard candles to determine the rate of expansion (the Hubble Constant). Once we know this value the age of the Universe can be established then, by association, the size of the visible Universe. We do not know how big the Universe it is, but it is a fair bet that the visible Universe is not the whole Universe. I'm not sure why one would assume the size of the Universe is fixed.
The Universe is expanding in either 4, 10, 11 or 26 dimensions; depending on which theory you take to be true.

Since at least one of those dimensions is time, what exactly does "expanding in the temporal direction" mean ? Getting older ? I guess I'm "expanding in a temporal direction", too, then (not to mention a couple of spatial dimensions). :-) StuRat 20:24, 5 August 2006 (UTC)

See arrow of time. --Fastfission 21:41, 5 August 2006 (UTC)

For one, the big bang is just a theory. Nothing can prove that it happened. Why would you assume that it is expanding? All things we observe in the universe are in an orbit around something. So it is possible that we , our galaxy, could be in orbit around something. This would be a large orbit that would be impossible for us to observe in our short life time. So we would assume that everything is moving away from us when it realy is not. For example, Haley's comet comes roughly every 80 years. For half of its trip it is moving away from us. The other half it is moving towards us. If this orbit was 1 million yeears insead of 80 it would be imposible for us to tell that it was in an orbit.

Using that logic you would expect about half of the galaxies to be moving towards us and half away, but almost everything is moving away. StuRat 05:35, 6 August 2006 (UTC)

If we could measure its trajectory precisely enough we could observe a certain curvature that corresponds with an orbit (would that be a hyperbola?). So the limiting factor is not time but precision. DirkvdM 09:17, 6 August 2006 (UTC)

Mind you, other galaxies are not just moving away from us, but accelerating away. Something that a little theory of mine predicted! See my talk page. The problem is that gravity should provide a countering force, ultimately causing the Universe to collapse on itself again (if there is enough matter in the Universe). But the opposite happens. My theory, however, actually uses gravity to explain this. If our galaxy is collapsing in on itself, we will be accelerating towards its centre, and thus away from other galaxies and silly us think that they are accelerating away from us. Once again we regard ourselves as the the unchanging centre of the Universe. When will we ever learn?

Still, there is the problem that local dynamics (within our galaxy) don't seem to fit in with this theory. Or do they? DirkvdM 09:12, 6 August 2006 (UTC)

All the glaxies are moving away from each other, not only away from us. Following the cosmological principle we certainly do not regard ourselves as the centre of the Universe. That gravity should be pulling everything together is correct, however there is a force driving everything apart (see cosmological constant). If DirkvdM's theory that the Universe is collapsing is correct, there would be evidence for this in changes in the cosmic microwave background. The collapsing Universe theory also doesn't explain why the further away galaxies are, the faster they are moving away from us. If this was caused by gravity the opposite should be true. It is also interesting to note that there are some theories suggesting that, over extremely large distances, gravity might be replusive.

Einstein called the cosmological constant the biggest mistake of his life. It has been re-introduced just to explain away the acceleration, but is not really based on anything, afaik. But my idea of falling towards some great attractor would mean that the further away something is, the faster it would accelerate away from us. That's a prediction I made (although at first I saw it as a flaw) before it was found to be true. That's a theoretician's wet dream and that's the reason I keep on persisting in it, despite the fact that I barely know what I'm talking about. :) DirkvdM 12:22, 7 August 2006 (UTC)

If all gallaxies are moving away from some center point then there should be some other gallaxies moving at the same speed in the same direction as us.

The universe is a four dimentional object and so no adequate explanation can be given to explain its shape or structure to someone who cannot percieve the fourth dimention. It has no centre point, Bill Bryson likened this to taking a person from a universe where there are only 2 dimentions to a sphere, the would find it incomprehendable that they could walk all round it and find no edges, and as such we cannot comprehend how we can travel indefeinitely in any direction at an infinite speed and find no edge, there is no edge that we can comprehend. If you travelled in a straight line for long enough, you would eventually return to your starting point, such is the shape of the universe. As a result there is no centre point. Galaxies are all moving apart. But not from a point that we can comprhend. Philc _T^E_C^I 00:49, 7 August 2006 (UTC)

If we travel long enough in one direction we will return to our starting point? That means that in reality everything is on a colision course. Which means that the universe is not expanding nor is the other galaxies moving father away from us.ĎÀČ

It is possible that if you travel far enough in one direction you will arrive back at your starting point, but it is not possible to test this theory.

Just imagine crossing the entire universe and then missing your starting point by 10 m. Then you'd have to start all over again. Ad infinitum. QED (I think). DirkvdM 08:08, 8 August 2006 (UTC)

Just to return to the original topic as shown in the title, on the other side of the Big Bank is probably the Big Mall, the Big Carpark, the Big Newsagent, the Big Lawyer's office and the Big Optometrist.  :--) JackofOz 14:16, 9 August 2006 (UTC)

Photorespiration in wild soybeans

Is photorespiration lower or higher in wild relatives of soybeans compared to normal soybeans? Why?--Patchouli 18:10, 5 August 2006 (UTC)

Kinetics of Oxalate/Permanganate

I'm a senior high school student doing (or will start doing) a kinetic study of the permanganate/oxalate reaction for my final grade 12 year. I have an idea of what I'm going to do and how I'm going about it, but I have a few questions about the experiment.
The equation for the reaction is the following: 2 MnO₄^-(aq) + 5 C₂O₄^2-(aq) + 16 H⁺(aq) --> 2Mn²⁺(aq) + 10 CO₂(aq) + 8 H₂O (l)

1. The reaction is very often mentioned as autocatalytic, which I have no reason to doubt. The problem is that most sources do not explain why this is so. The closest to an answer I've seen is something to do with the manganous ion produced collides with manganese complexes and this speeds up the reaction, but even then I could be wrong since I saw this in one source that tried to explain it. Then that doesn't really help me either, even if its correct. Some clarity on that would be appreciated.

2. The reaction procedes in an acidic solution. Would the rate law look like this: rate = k[MnO₄^-]^x[C₂O₄^2-]^y or do I have to add the proton (like [H⁺]^z) to the equation?

3. I've read some experiment writeups where sulfuric acid was added to the reaction. Does it have to do with the reaction needing to be acidified? Would it be required if I used say oxalic acid instead of sodium oxalate (although oxalic acid isn't very strong)? Another explanation I've found is that it destroys the permanganate and speeds up the reaction and otherwise this reaction would take too long. Any ideas?

Thanks in advance.--72.56.179.48 19:35, 5 August 2006 (UTC) Adam Friedman

If you look at the basic equation you have written, you will see that it requires, at least theoretically, for two negative ions to react together. This would indicate that the reaction has high activation energy. You must look at the way the two manganese-containing ions react together. Secondly, you cannot predict the rate equation by looking at the balanced chemical equation. Rate equations can only be worked out by a series of experiments, for example, varying the concentration of H⁺ ions. Thirdly, the reaction is a very heavy consumer of H⁺ ions. These can only be provided by a strong acid. The original ethanedioic acid is far to weak to do this.--G N Frykman 21:01, 5 August 2006 (UTC)

Thanks for the above. Regarding the interactions of the manganese ions, is there a relatively simple way to explain it? I mean the manganese ion in permangante is reduced the 2+ state, so it must collide/interact. But can someone offer some sort of explanation regarding the interaction of the manganese ions and how this contributes to the autocatalytic nature of the reaction? (Or perhaps offer a basic idea of an experiment I could do...)

Thanks Again. --72.56.179.48 01:08, 6 August 2006 (UTC)

I didn't want to give you all the answers at once! Manganate(VII) and manganese(II) ions react together in a reverse disproportionation reaction to produce manganese(III) ions. It is these which oxidise the ethandioate ions to carbon dioxide. You will see that, as opposed to two negative ions reacting together, we now have a positive ion and a negative ion reacting. This can't happen, of course, until some manganese(II) ions have been produced by the slow reaction of the two negative ions. There is a hint of an experiment that you could do on the page autocatalysis.--G N Frykman 09:11, 6 August 2006 (UTC)

Yes, its ok not to want to give me all the answers all at once. Now that it was brought to my attention, I remember seeing in a journal article I read what is presumed to happen in the reaction in terms of how the maganese ions are reduced. They had three equations, and one of them was something like the following: Mn (VII) + Mn (II) → Mn (III) + Mn (VI).
Then it says that the 3+ species is destroyed in a reaction with the oxalate species, actually now I that I think of it, like you mentioned. So I offer my thanks. I will next check the autocatalysis page. Again, thanks. --72.56.179.48 19:06, 6 August 2006 (UTC)

electromagnetic fields and radiation pressure

What is the difference between the lorentz force exerted by electrostatic and electromagnetic fields and the raditation pressure of electromagnetic radiation pressure. Secondly I saw an article in the 70s where small glass balls were levitated by electromagnetic radiation pressure, what is the largest and heaviest object moved by radiation pressure to date? Curiosgeorge

It's worth reading the articles
The most important difference between them is that the Lorentz Force only acts on charged particles; radiation pressure can be exerted on anything. The Lorentz force will also make charged particles move along curves, rather than straight lines. I'm afraid I don't know what the most massive objects moved by radiation pressure (in an experimental setting) are, but using radiation pressure to propel spacecraft is an active area of research.

The Lorentz force is the force that electromagnetic fields exert on charge particles. "Radiation pressure" is an interesting macroscopic example of the Lorentz force, but nonetheless they are really the same phenomenon. Both the lorentz force and radiation pressure only affect charged particles. Luckily, most matter is made of charge particles - protons and electrons. You might be interested in the Yarkovsky effect, which is an interesting example of the momentum of radiation affecting astronomical bodies in an unusual way. --Bmk 01:57, 6 August 2006 (UTC)

The radiation pressure exerted on an area, A, is given by (dp/dt)/A (where p is momentum). This does not involve any charges. It's an application of conservation of momentum.

There can be no radiation pressure without charges. All atomic matter consists of charges - electrons and protons. The only way for radiation to exert a pressure on a solid is if the solid contains charges; the electromagnetic field only interacts with charged particles. --198.125.178.207 18:47, 7 August 2006 (UTC)

That's not right, light carries momentum and when it is absorbed or reflected by an object, it transfers that momentum to the object. Light even though it does not have mass, has energy, and therefore can transfer momentum. This is an often overlooked effect of relativity. Dan 15:15, 10 August 2006 (UTC)

Vinegar reacts with hairspray to form a solid

A strange elastic white porous soild formed when I poured vinegar into a hairspary formula (40% alcohol) at room temperature and standard pressure. I smell the ethyl acetate, but that doesn't explain the solid. Can someone tell me what happened?

Do the ingredients of the hairspray list something like sodium benzoate? You have probably precipitated the insoluble acid (eg benzoic acid) of a soluble salt by lowering the pH.--G N Frykman 20:52, 5 August 2006 (UTC)

I once had to inject small amounts of benzoic acid into rubber-stoppered vials via a small guage needle and syringe. I can attest to the fact that benzoic acid is indeed very stringy and very sticky. Indeed, I'm pretty sure I never was able to get it in, and had to pick another chemical.Tuckerekcut 23:52, 5 August 2006 (UTC)

Nitpick: you can't pour anything into a formula because that's something abstract. Referring to the mix in the canister as a 'formula' is commercial blah. DirkvdM 09:27, 6 August 2006 (UTC)

Counter-nitpick: Any mother or half-interested father knows that what goes into a baby's bottle is usually called a 'formula'. Scientists are humans too (mostly).  :--) JackofOz 01:32, 7 August 2006 (UTC)

I think any combination of chemicals can be called a formula. — [Mac Davis] (talk)

Well formulated. DirkvdM 08:08, 8 August 2006 (UTC)

Nice, a precipitation. --Proficient 04:29, 9 August 2006 (UTC)

Intercalating agents and you

I'm a labworker and during my work I get into contact with many nasty substances like ethidium bromide and DAPI. I tend to handle these substances (even in heavily diluted form) as if they were death incarnate. Sadly I'm also an incredible clutz and did get some DAPI on me and possibly in me. Of course I freaked out like no tomorrow especially because there is so very little known about the substance at hand. There are however quite a few other substances like this like Benzopyrene and Alfatoxin both of which, if I can believe the wikipedia articles, occur in my toast with peanutbutter (all be it in small doses).

Yet both these substances are flagged as highly carcinogenic (just like ethidium bromide and DAPI). So why aren't we dying of cancer left and right. Given the world we live in, with it's smoke, bbq's and crispy brown baked bacon, we should be accumalating this crud in our system at a staggering rate. So what gives? Am I missing something here? Can the body " deal " with these molecules shunting themselves between our precious base pairs thus causing happy frame shift mutations and the like? - Pascal

First, are you sure they accumulate instead of passing through the system ? Second, perhaps the dosage is insufficient to cause a problem. Third, perhaps it's not in a harmful form (for example, elemental mercury is far less dangerous than methyl mercury). StuRat 21:43, 5 August 2006 (UTC)

Alas, I remember the first time I spilled EtBr on myself. I freaked out too, but my reaction was decidedly less pronounced the 100th time. I'm not sure what the wikipedia article says (perhaps I'll stop by later), but EtBr (as well as DAPI) is not carcinogenic per say, but mutagenic. Much like UV radiation and charred carbohydrates, it is advisable to limit exposure, but don't worry so much that it takes over your life. From what I have learned from working with some geneticists who were working on their degrees before Watson and Crick even published, use gloves whenever possible (nitrile gloves) and if you spill a little you spill a little. In situations where you are working with visible dilutions (solutions which are visibly colored by the stain, red for EtBr, or blue/green for DAPI) double glove, and walk don't run to the shower if you spill on yourself. Gels (even mildly colored ones) are usually not a big deal for contact exposure because not much chemical is available at the surface. Basically, freaking out about a spill isn't gonna help you much, and as long as you haven't succombed to any toxic effects, the mutagenic effects can't generally be reversed specifically after the fact. Really the best protection is to stay healthy with a good diet and plenty of excersize. The human body has a slew of cancer-peventing mechanisms, utilizing many levels of protection at different teirs of biology (i.e. promoters/demoters in genes all the way to cells that scavenge for budding neoplasms). In short, lots of stuff can cause cancer, but we have pretty good defences. The goal is limited exposure, not necessarily zero exposure.Tuckerekcut 23:48, 5 August 2006 (UTC)

Good points made above. I also work in a lab and agree that you have to accept some element of risk, but work to minimize it. The point i wanted to make is that we simply do not know what the mong term effects of working with substances like EtBr or DAPI is. It could well be that they are carcinogenic to humans even at a very limited exposure, but corrolating increased cancer rates with lab workers will be very difficult to do. A lot of chemicals we are exposed to are called carcinogenic, usually because in some study somewhere - after exposure to ridiculously high doses - mice were shown to have an increase in tumour development compared to controls. If you live in California you would be amazed at the things that, according to state law, must be explained to you that they could cause cancer.

Poor old Marie Curie found out that working with material we do not fully understand can have pretty nasty effects, that is why we treat lab chemicals with such care, probably more than we strictly need to, on the principle it is better safe than sorry (and also to stop litigation based on the due care an employer owes their workers). That said, risk is relative, if i were you i would worry looking left and right when crossing the road than about suffering from EtBr exposure. Rockpocket 03:44, 6 August 2006 (UTC)

Thanks for the replies guys. I had already talked to the institute's doctor and he had already assured me that I didn't have to much to worry about, but your words of wisdom are always welcome. Also thanks for the advice for wearing nitrile gloves. I used to wear those dinky medical examination gloves (standard in our institute) untill I found those nitrile gloves. The nitrile gloves fit me better, cover the wrist area well and offer better protection so I'm sticking with them. Though I won't be returning to the labs soon (It was an internship of mine) I feel better prepared now.

I heard in a documentary on the Chernobyl accident that exposure to moderate doses of radiation aren't as harmful as one might expect from the effects of higher doses and might actually even have a positive effect, almost like a vaccination, causing the body to counteract cancer even though the doses aren't high enough for it. But that is speculation. DirkvdM 09:44, 6 August 2006 (UTC)

One of the reason that medium levels of radiation are often safer than low levels of them is because of the way that radiation affects the cell. In a rather simplistic form: if one particle hits the cell, you get a mutation (and potentially cancer). If two hits the cell, the cell just dies. So there is supposedly a level in between low and high in which cancer is less likely, since most of the cells that would be cancerous would end up just getting killed instead of surviving from their exposure. Or something along these lines. There is a lot of uncertainty and debate on the question of low-level radiation, I should point out. --Fastfission 16:29, 9 August 2006 (UTC)

actually the phenomenon is well precendented. it thought it was called hysteresis, but the wiki article doesn't mention much about its relevance to biology. it might be another h-word. Xcomradex 11:13, 6 August 2006 (UTC)

Just to be clear, the reason for using nitrile gloves goes beyond mechanical resilience. Ethidium Bromide is able to migrate through latex barriers with little difficulty (a phenomenon not often observed because latex so effectively stops the primary solvent for EtBr, water); and based on its similar ability to cross cell membranes, DAPI is likely to be able to do this too. Thus nitrile gloves offer barrier protection from these stains while latex gloves do not. I'm not so sure about other materials, though.Tuckerekcut 23:18, 6 August 2006 (UTC)

Strangely enough everyone in the institute uses latex gloves for just about anything. This makes sense because heck I could only scrounge up 1 box of nitril gloves in the intire institute. I think the institute needs to adjust it's safety protocols. - Pascal

how a snowboarder turns around while on the air

As far as I am concerned, things need stable things to move. (Car-Road, Boat-sea). So how a snowboarder turns around in the air an astronout in space without touching anything else. if so which musles are more likely to be used while in the action? Any relevant answer would be much appreciated...

You can change your direction in the sense of turning around by simply shifting your own weight around. You can't change the path you are on very radically though—i.e. if you were thrown to the left, you could just throw yourself to the right without some sort of friction involved. --Fastfission 23:29, 5 August 2006 (UTC)

When snowboarders go for a jump, they give themselves some angular momentum by pushing off in the right way. Since they are also moving quickly through the air standing on a large board, there is significant air resistance which they can use to turn themselves. --Bmk 02:00, 6 August 2006 (UTC)

If an astronaut can't push against anything, that means his centre of gravity can't move. But that doesn't mean he can't turn around his own axis. If he stretches out his arms and swings them both to the left, his body will rotate to the right. His arms will wrap around his body, thus accelerating the rotation, like a figure skater. This rotation will continue until he moves his arms back again. To come to a stop he would have to do the same in reverse. If he would just move his arms back along his body (not outstretched) the rotation would merely be diminished. I think. Even thought the reasoning sounds right, it still feel counterintuitive, so I understand your question. I have wondered the same thing about 'accelerating' on a swing. I still find it hard to reason how this would be possible, but the person on the swing is excerting energy and that has to go somewhere. DirkvdM 10:09, 6 August 2006 (UTC)

The astronaut would only continue spinning until his arms stopped moving, then he would stop spinning; conservation of momentum prohibits him (or her) from gaining angular momentum. Basically, he can swing his arms, and his body will rotate a certain amount, but it will not continue to rotate unless he rips off his arms and throws them across his spacecraft, which is strictly against NASA regulations. --Bmk 13:25, 6 August 2006 (UTC)

Citation needed ? --DLL 16:59, 6 August 2006 (UTC)

How would you explain being able to increase the amplitude on a swing without violating the conservation of momentum? DirkvdM 13:35, 7 August 2006 (UTC)

Interesting question - after thinking about it, i think the way a person is able to increase their energy while swinging is because they are connected to the swing set by the rope. Basically, when they are swinging, they can use their muscles to elevate their body by pulling on the rope, thus adding potential energy to the motion, which is converted to more kinetic energy when they stop pulling. Momentum is conserved in the earth-swinger system. Oh, and by the way, I should have cited conservation of angular momentum in my first comment. --18.239.6.57 15:02, 7 August 2006 (UTC)

The arguments of conservation of momentum (be it linear or angular) or energy and such take a step back, looking at the system as closed and saying nothing can enter or escape. You say the person on the swing converts energy stored in their body to create (angular) motion. Can't the astronaut do the same? Then again, I recognise that they couldn't create linear motion that way, so I'm still stuck on this level. But in detail, the trick is to give the impulse in one direction with outstretched arms and then moves the arms back along the body. I'm not sure they would keep on spinning (I suppose they wouldn't), but if they keep on repeating this, they could keep on turning. DirkvdM 08:20, 8 August 2006 (UTC)

Right - the trick with the swinger is the system in which angular momentum is conserved is the entire swingset-swinger system. In the case of the astronaut, there's only the astronaut - if he wishes to have some angular momentum, there are no other parts of the system to which he can impart the opposite angular momentum to maintain conservation (unless he's allowed to blow air). And the astronaut would not actually be able to keep on turning - his angle will be limited (this is all neglecting air resistance, which would allow him through use of aerodynamics to gain angular momentum). Try it on a good swiveling chair - one with very low turning resistance. You should be able to verify that without the help of the resistance on the chair bearings, you are not able to continue turning after you arms are maximally twisted and stop twisting. --Bmk 20:19, 8 August 2006 (UTC)

Interesting. --Proficient 04:30, 9 August 2006 (UTC)

August 6

metals and armor

i was wondering that if i were to make plate mail armor what would be the best metal for the job, by best i mean strong yet light, but wont dent or hardly dent when hit, thank you.

I would actually use Kevlar. It would meet all your requirements except that it is not metal. Titanium is a good metal candidate but I do not think you would find metal that is light and wont dent easily. Skapur 04:28, 6 August 2006 (UTC)

Yeah, you probably don't want to mess with real armor. Those knights were crazy strong. If you actually want it to protect you, the article armor has some suggestions, one of which is apparently 15 times stronger than steel, and fairly comfortable. If you're going for a recreation, iron might be accurate, but something light like tin foil on cardboard is way more practical, especially if you live someplace hot. Black Carrot 06:31, 6 August 2006 (UTC)

Titanium would be the best, but it's very expensive. Kevlar is a better armour, but you can't make plate mail out of it. The Guy From Ipanema

I would recommend avoiding titanium, or any other hard and truly dent-resistant metal. These properties will also make the metal extremely difficult to turn into armor, which is done by cutting the metal then bending and shaping it with a hammer. Plain steel is strong and light enough for body armor. Stainless steel is much harder to work, but looks nicer (and is still much softer than titanium). I recommend starting with plain 16 gauge steel plate. If you care enough to make your own armor, you can care enough to polish it and keep a fine coat of oil on it so it looks nice!--Kerry 20:48, 10 August 2006 (UTC)

Electrical

What is the name of the electrical component that converts "noisy" electricity (e.g., that produced by a power plant) into electricity that is "clean", suitable for use in appliances (e.g., air conditioners etc)? I know this is a bit vague, but I figure someone might know what I am talking about. BenC7 03:26, 6 August 2006 (UTC)

A power conditioner regulates voltage and reduces noise in a power signal so that it is suitable for sensitive computer or audio equipment. A series of transformers reduces the voltage from the power plant to the voltage which can be used in houses. Hope that answered your question. 48v 04:30, 6 August 2006 (UTC)

Actually a large power plant produces clean electricty to begin with. Small electric generators tend to be quite noisy and a power conditioner helps. Skapur 04:42, 6 August 2006 (UTC)

Yes. The power plant energy is fairly clean; however, by the time it is transmitted to end-users, there is noise and voltage variation which can be problematic to sensitive equipment. 48v 04:57, 6 August 2006 (UTC)

Perfect! Thanks. BenC7 10:21, 7 August 2006 (UTC)

trying to identify a mineral/rock

hi, i wanted to ask what this mineral is, it is a bit lighter than a cap eraser, and has a shiny silver-graphite look too it with maybe a hint of light blueish shade to it(barely visible), and has no other colors on it.

Well, it could be graphite, as you say, or mica, that's also shiny. It would help if you said where you found it, or uploaded a photo. —Keenan Pepper 05:12, 6 August 2006 (UTC)

Sounds a little like hematite, but hematite is pretty dense (I assume when you say it's lighter than a cap erasor, you mean it's less dense). --Bmk 13:29, 6 August 2006 (UTC)

trying to identify a mineral/rock 2

this is for the question right above me, it was biotite mica, thanks

Just so you know, you can (and should) put anything relating to a single query in the same section - you do that by clicking the little link marked 'Edit' on the far right of the section header. Confusing Manifestation 07:19, 6 August 2006 (UTC)

Oh, and you should always sign your posts on pages such as this with four tildes: ~~~~, which then becomes something like this: Confusing Manifestation 07:23, 6 August 2006 (UTC)

When you say that it manifests itself as something that might be confusing to newbies. :) DirkvdM 11:19, 6 August 2006 (UTC)

Cool, I guessed it! Glad to have helped. —Keenan Pepper 08:07, 6 August 2006 (UTC)

Hair fall problem

Hi All, Im having a very serious problem : my hair is falling cont. and it has become too weak,dry and unhealthy. Could anybody please suggest me an appropriate site where I can get some help, or advise me.

Shave your head. You don't say if you're male or female, but you could shave it in either case. Don't forget to put sunscreen on your scalp. —Keenan Pepper 08:06, 6 August 2006 (UTC)

Im a female in my early twenties, and there is no way im shaving my head.

Oh, sorry. In that case I'd say either try a new shampoo, or talk to your doctor or hairdresser. —Keenan Pepper 09:24, 6 August 2006 (UTC)

It's normal for hair to be falling continuously, so if the ammount of falling hair has not increased, then there's no problem. (However, it's easier to notice fallen hair if your hair's long, as women's hair can be.) --Kjoonlee 10:35, 6 August 2006 (UTC)

And men's hair, for that matter. No discrimination, please. :) DirkvdM 11:21, 6 August 2006 (UTC)

I used to lose a lot of hair, in the sense that I had a receding hairline (so actual loss). When I was in my late twenties I stopped using shampoo. At first I started losing even more hair, but luckily I persisted and after about a month there was a noticeable improvement. At the moment I'm in my fourties and still have a fair amount of hair (check out the photo on my user page (click on my signature), although that doesn't show the bold spot at the back). My brother lost about as much hair as I did, but he kept on using shampoo and by the time he was in his fourties he was almost bold (although that doesn't really prove anything, but it's an indication). I should also mention that I had already switched to baby shampoo, so you might try that first. Maybe it's enough to stop the hair loss. Also, at first your hair will get greasier because it's used to compensating for the shampoo. But after a while it will adapt (back to normal, really). Showering with water really is enough to keep your hair (and your body) clean. Soap is only necessary when you've been to the toilet. DirkvdM 11:14, 6 August 2006 (UTC)

While your answers are frequently "bold" (for their total lack of supporting evidence), the word to use here is "bald", meaning "devoid of hair". I will now revise the way I view you, from an ultra-liberal, pot smoking hippy...to a greasy haired, balding, ultra-liberal, pot smoking hippy. :-) StuRat 07:08, 7 August 2006 (UTC)

Not ultra. Never ultra. Pretty liberal yes (in the Dutch sense, which corresponds to what in the US is called libertarian, I believe), but with a sufficient amount of socialism thrown in for balance. And not greasy either. You haven't been paying attention again, have you? Read my post again. DirkvdM 13:42, 7 August 2006 (UTC)

I read what you said about it not being greasy any more, I just don't believe it. You just got used to it being greasy, similar to how smokers can't tell they stink of smoke, after they get used to it.StuRat 10:31, 8 August 2006 (UTC)

Thyroid problems, vitamin & mineral deficiencies and hormone changes can cause hair loss. The dry, shedding hair is definitely a symptom of hypothyroidism. The internet is great, but I'd suggest seeing your doctor.--Anchoress 11:34, 6 August 2006 (UTC)

• You didn't specify if it's falling down and becomes straight or if it's falling out. In either case talking to a doctor and a hair dresser would be your best option. - Mgm|^(talk) 20:52, 6 August 2006 (UTC)

• Try a moisturizing conditioner after you shampoo. Also, avoid swimming in pools, as chlorine can have just the effect you described, and try not to use a blow dryer. Question: Are you on a low fat diet ? These can reduce the natural oils your hair follicles produce. If so, I suggest a "healthy fat" diet instead, where you avoid trans fats and animal fats (except fish), but get lots of vegetable oils. StuRat 07:15, 7 August 2006 (UTC)

Thanks all, it really helped me.

Already? In my case it took a month. DirkvdM 13:42, 7 August 2006 (UTC)

Answering StuRat, no im not on a low fat diet, and I thanked you guyz for your suggestions,it helped me understanding the problem more (for DirkvdM). Hoping to get more from you all, wondering if someone can suggest some health site where I can get help from experties.[who asked the question].

Soap is NEVER necessary (at least, not the kinds sold in stores). Sorbolene does a damn fine job, does not produce allergenic reactions, makes the shower a whole lot easier to clean, leaves no residue, and leaves the skin smelling naturally fresh and sexy in a way that soap cannot hope to emulate. I thoroughly recommend you ditch your soap supplies and get some sorbolene. It might cost a little more, but it's worth it. JackofOz 12:21, 8 August 2006 (UTC)

To put the conventional medical view for a moment, if you consult your doctor there are a number of more-or-less effective medical baldness treatments available. Your doctor may also investigate further to determine whether the thinning hair is related to some other medical condition. --Robert Merkel 15:09, 10 August 2006 (UTC)

visual basic

Moved to Wikipedia:Reference_desk/Computing#visual_basic.

Unchangeable Body Weight

In an average male person of 70kg, how much of that is not fat or muscle - i.e., mass that can't be "modified", so to speak. I know that erythrocytes comprise about 3% of one's body weight, how about all organs, bones and so forth? Jack Daw 12:27, 6 August 2006 (UTC)

Your bones usually make up about 20% of your body weight.

I don't know why you need this information, but for all purposes relating to fitness, you might use the BMI (body mass index). For men, 7% body fat is considered good, while anything over 20% is considered obese. For women, these thresholds are much higher due to the adipose tissue reserves found in a woman's breasts.

Tissue energy demands

How much energy (in kcals) does the body use at rest? Or at mild to heavy work? Also, you always hear that muscle requires more energy than fat. How much more? Jack Daw 12:44, 6 August 2006 (UTC)

See basal metabolic rate. — [Mac Davis] (talk)

Right, that answers my first question. And the others? :) Jack Daw 18:32, 6 August 2006 (UTC)

I read on a weight training website that every pound of muscle you gain burns an extra 60 calories, but I don't know if that's accurate.--Anchoress 21:55, 6 August 2006 (UTC)

I can't believe I only read the first sentence! Were the questions there before? Mild to heavy work: It depends on what work you do. It is different with every person too. Muscle requires more energy because it consumes a lot more. You do more work with muscle than fat. Fat is more so stored energy, while muscles is more used to release energy. — [Mac Davis] (talk)

http://muller.lbl.gov/teaching/Physics10/PffP_textbook/Chapter01.htm search for "Human power";. HIgh expenditure, about 1 horsepower = 746 watts for brief moments, or about a 100 watts sustained. If you are an Olympic athlete maybe you can do a horsepower sustained. "you always hear that muscle requires more energy than fat." Please rephrase your question. --GangofOne 06:22, 7 August 2006 (UTC)

Let me quote Dieting: "Ideally, overweight people should seek to lose fat and preserve muscle, since muscle burns more calories than fat." It's the last part I'm wondering about; how many more calories? Jack Daw 15:13, 7 August 2006 (UTC)

Right, my question too. I have never heard that and it sounds like complete nonsense. The body burns fat to operate the muscles. Or do you mean that making and storing fat requires energy? Probably. But then I still don't understand the statement. The two can't be compared (at least not without more info). DirkvdM 13:54, 7 August 2006 (UTC)

What do you mean by 'nonsense'? There's no need for an attitude. Jack Daw 15:13, 7 August 2006 (UTC)

I have no attitude (ahem...), I just care about the truth. DirkvdM 08:26, 8 August 2006 (UTC)

Don't call people's questions "nonsense" then, that's completely uncalled for. Jack Daw 14:13, 8 August 2006 (UTC)

If you have 2 pounds of muscle and 2 pounds of fat, the fat will provide energy as well as using some small amount to maintain the fat cells, the muscle will use up energy every time you move as well as using some for the maintenance of the cells. Your 2 pounds of muscle uses more calories than your 2 pounds of fat. If you weigh a set amount, if more of it is muscle you'll use up more calories. Not nonsense. But I'd like to know how many more too. Skittle 19:27, 7 August 2006 (UTC)

Ok, so pretty much what I thought. It was just stated in an awkward fashion. DirkvdM 08:26, 8 August 2006 (UTC)

Bio-0 electricity volume and question

How much bio-electricty can be generated by the human body? I read from a work of a biochemist that works for the US government Dr Mayne R Coe that in theory one cubic inch of the human leg tissue can generate 400 000 volts at low amprage, but this is only at max output and if a high amprage reaction sparked it off. Is this true? What is the general amount present in the human body including neurochemical electricty?

Secondly Why is there no wikipedia page on "high voltage syndrome" the case where an individual generates more bio-electricity than normal with strange side effects? It is documented in medical journals such as "journal das debats" and in reports such as the ones from the ontario medical assosiation and mentioned in books such as "anomaloies and curiosities in medicine" and "abnormal hypnotic phenoemena"

Robin

Feel free to start the article yourself! It's your encylopedia too. However, I have to say I don't think there's much truth to this idea. Our somewhat dubious article bio-electricity could be of use. There are small macroscopic voltages from body part to body part, but they are on the order of millivolts. There is also a small but significant amount of energy in the electrical signals of neurons, but it also isn't much. Mainly the body stores energy in chemical form (which, if you really get down to it, is electrical energy anyways). You might be interested in the article voltage, also. --Bmk 13:56, 6 August 2006 (UTC)

I think that may be wrong, the brittanica encyclopedia claims http://www.britannica.com/eb/article-9079250 that each cell membrane has an electrical potential of around 50 millivolts, and there are millions of cellmembranes in operation in your body at a time. Any comments? Robin

Sure, many/most neurons, for instance, have a resting potential of around -70 mV (really it varies widely). It's caused by a separation of ions across the membrane. But when you open up an ion channel to let the membrane reach equilibrium, you're talking a very tiny amount of current that flows (I don't know an actual value offhand, but my guess is it's down in the nanoamp range). You'd be hard pressed to find an efficient way to actually use such a tiny amount of electricity, especially as you'd probably have to "tap" each cell individually. digfarenough (talk) 16:01, 6 August 2006 (UTC)

Thank you, but can anyone tell me exactly how many millivolts/ volts are in the human body on average, combinding the cell membranes, neurons firing etc the brain, limbs, nerves etc. the whole thing. How much coltage wise? Robin

Well the root of your confusion may be a units problem! A volt can be transformed around quite a bit via electronics and chemistry. For example, see Ohm's law relating voltage and electric current What is really relevant is the electric power. Realistically, there is not much electrical power floating around (probably in the neighborhood of microwatts to milliwatts; i.e. hundreds of times smaller than the chemical or mechanical energy inside a biological organism). The form that this electrical energy takes may be ionizing a cell-membrane, which could be very small (maybe millivolts), or synaptic junctions, which could reach volts for very short time intervals. It's not very common to talk about the "total number of volts in the body" because you can't just add them all up as if they were grams. Voltage must always be measured between two points - you can conceptually think of it a bit like "distance" - you can't really have the "total number of distance" either. But the end result is that not much electrical energy is floating around at any given time, no matter how you slice it. Nimur 12:46, 7 August 2006 (UTC)

History of Household Appliances

I am trying to find information about when household appliances such as hot water heaters and refrigerators were first manufactured and sold in the US. Any assistance would be greatly appreciated.

joc_trebor

According to our article about refrigeration, Alexander Twining was the first to introduced a commercial refrigeration device to the US in 1856. --Bmk 14:03, 6 August 2006 (UTC)

As for hot water heaters, they were preceded by cold water heaters. --DLL 16:49, 6 August 2006 (UTC)

A google search on "technology timeline" gives a very good list of resources. You could also look at articles for specific appliances in wikipedia, or google. Please "search first". 48v 17:18, 6 August 2006 (UTC)

I'll skip the 'hot water heater' (DLL already covered that) and move on to the next question. Do you mean 'electrical'? Heating water over a fire has been done since prehistoric times. And refrigeration was done in the middle ages (and possibly before that, but the US didn't exist then) by storing ice in deep pits, where it stayed frozen all summer long. Simpler cooling methods use evaporation, just like electrical refrigerators, except that evaporating water is a lot simpler - just wet a towel and put it on whatever needs refrigerating. DirkvdM 14:02, 7 August 2006 (UTC)

dual core processor

If apple or dell mentions a dual core processor to be 2 GHz in speed, then will its speed be equal to a 2 GHz single core processor or will its speed be equal to 2 x 2 = 4 GHz? ie. twice a 2 GHz single core processor?

ThankZ

Generally, they are talking about the clockspeed of each chip, so you will have two 2GHz chips (actually, half-chips) but it is an oversimplification to say that thats actually 4GHz in total as they are speeds, and not completely additive. 48v 17:21, 6 August 2006 (UTC)

The processing speed of the cores will each be 2GHz, but this does not mean that together they achieve 4GHz. The Dual core will do things quicker only because more tasks can be performed simultaineously at that speed. The Guy From Ipanema

If the clock speed is 2 GHz, then that's what it is. If you have two watches, that doesn't mean they go twice as fast. In case you meant performance-equivalent, I can't give you a figure, but it'll probably be under the performance of a 3 GHz single-core. Getting two processors to work on the same thing is very difficult. They would spend a lot of time waiting for the other's results before they can proceed. This is one of the most difficult programming tasks one can face. So it depends much on the programs that run on them, too, unless there is some very clever operating system that has a general solution to this. DirkvdM 14:10, 7 August 2006 (UTC)

The "speed" is indeed 4 GHz total since each chip is operating at 2 Ghz. That doesn't mean much though, since the speed of applications and such is what you are probably concerned with. It wouldn't be equivalent to a 4 Ghz processor though. Plus it also depends on the model of the dual core processor, as many cycles are wasted or not used efficiently. --Proficient 12:12, 10 August 2006 (UTC)

Hep C and organic sulfur

The question is what is the correlation between organic sulfur, bio available sulfur and Hep C.

The reason I ask the question is Dr. Burton M Berkson reported on MedPlus in 1999 three cases of liver regeneration with IV sulfur based amino acids and selenium in about a year of treatment. Currently Hep C is addressed in the medical community with either liver transplants which often are infected after the transplant and Interferon chemo therapy which has limited applications. Being that Dr Berkson article dates from 1999 I was curious about the sulfur link being that a Member of the Live Blood Study had the same results ingesting 12 grams of organic sulfur which he obtained from the Study in 15 months. His viral count drooped 7 million and his biopsy demonstrated healthy new liver cells. We in the Study believe that considering the nature of Hep C the availability of bio available organic sulfur could be a factor in this deadly viral infection. Viruses hate oxygen and sulfur as well as selenium enable the transport of oxygen across the cell membrane as described in David Gregg's Ph.D article “MSM and DMSO the oxygen transport pair.” It is also the belief of the Study that this lack of sulfur in our diets can be tied to two things: First the use of chemical fertilizers in the US, 1954, and the use of chlorine to purify our water systems, chlorine is an effective block for the uptake of sulfur. The results of the Live Blood Study have yet to be published to date but this information regarding Hep C and other viral infections appears to be too important not to address and we in the Study would welcome any input regarding a possible treatment of all viral disease which has no side effects.

Patrick McGean Director Live Blood Study of the Body Human Project

search google for the Live Blood Study under “Patrick McGean.”

Please state the citations to the Berkson and Gregg papers. Also, please give a url, do not ask us to search google. I tried and all I got back was a big pile of medical pseudoscience and I couldn't see the good information you are referring to. --GangofOne 01:16, 7 August 2006 (UTC)

seems there might be something in it, but the treatment is in early days (phase 1 published in 2005). i guess that doesn't stop snake oil peddlers from making a few dollars at the expense of an increasingly scientifically illiterate public.

phase 1 trial: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?itool=abstractplus&db=pubmed&cmd=Retrieve&dopt=abstractplus&list_uids=16082287

Xcomradex 08:36, 7 August 2006 (UTC)

fyi, patric mcgean sounds like little more than another conspiracy theorist who had one too many glaucoma treatments.

http://oneutah.org/2006/01/22/more-about-oneutahorg/

Xcomradex 08:42, 7 August 2006 (UTC)

and interferon+sulfur/selenium compounds are no more effective than interferon alone in treating HepC

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=10517313&query_hl=8&itool=pubmed_docsum

that about does it i'd say. Xcomradex 08:51, 7 August 2006 (UTC)

the white living things on lobsters

I was in a store the other day and saw a lobster tank. I went over to take a closer look and there were white things all over this lobster on its head and one of its claws. The white things were in a mound and had some kind of living thing in the center of it that would go in and out of the mound. It was small and looked like a fan. I have looked everywhere and cant find out what they are. So what are those white things living on the lobsters?

Try Barnacles. 48v 18:58, 6 August 2006 (UTC)

thank you very much

>> Whales have something similar the are refered to as whale lice, but are accutually crustations, they live on the whale and reproduce.--Aaron hart 09:39, 9 August 2006 (UTC)

Death by Dreaming

According to popular beliefs, if a person dies in his or her dream, that person would die in real life. This this belief true? If it is true, why is that, and if it is not true, what ths the rationale behind the belief? --72.57.219.186 18:59, 6 August 2006 (UTC)

No, it isn't true. I die in my dreams all the time (usually by falling off of tall things, I always seem to lose my balance in my dreams; though the other day I was shot in the gut! A bit more violent than usual, and my sides actually clenched when I woke up immediately after). The rationale behind the belief is probably just that people of all cultures have regarded the reality-state of dreaming to be a mysterious area, one ripe for mystical speculation and myth-making, and have believed that it can enter into one's waking life as well. Though it would seem snarky to postulate that Freud's theories on dreams were just a modern extension of this, he himself acknowledged as much in his The Interpretation of Dreams at many point, placing himself in the tradition of those who in the past believed that the life of the dreamer and the waker were intimately connected. My personal favorite approach to this is Borges' The Circular Ruins. --Fastfission 19:13, 6 August 2006 (UTC)

Actually, it's perfectly true. If you die in your dreams, you're guaranteed to die within the next 200 years. Until medical science makes a major breakthrough, at least. Confusing Manifestation 00:38, 7 August 2006 (UTC)

200??--Light current 01:25, 7 August 2006 (UTC)

I'm giving a cautious overestimate. Just because the actual value is, at the moment, around 120 (assuming that the world's oldest people dreamed of dying in their first few years of life) doesn't mean that there won't be someone who dreamt of dying 100 years ago, and in 100 years time (thanks to aforementioned medical breakthroughs) says "That's funny, that guy on Wikipedia said I'd be dead by now." Assuming they've managed to cure Alzheimer's as well as everything else. Confusing Manifestation 00:15, 8 August 2006 (UTC)

Are you...serious? This isn't the Matrix, maybe you forgot... ? --mboverload@ 10:26, 7 August 2006 (UTC)

If soneone is already weak, the shock of a nightmare might do them in, I imagine. DirkvdM 06:26, 8 August 2006 (UTC)

evolution of white skin

hi, given that black skin burns less and is less suceptible to skin cancer (this may not be true, its just something i've always assumed), what is the evolutionary advantage of white skin? is there one? given that we're all supposed to have come from afica originally, it seems bizarre that people in colder climes have different pigmentation when it doesnt serve an (obvious) purpose. any enlightenment would be much appreciated- thanks 200.166.84.18 19:19, 6 August 2006 (UTC)

Does skin pigmentation help at all? digfarenough (talk) 19:34, 6 August 2006 (UTC)

The short, simple, general reason given is that pale skin is able to produce more vitamin D from less sunlight. Skittle 20:22, 6 August 2006 (UTC)

Which is quite useful in less than tropic localities. - Mgm|^(talk) 20:50, 6 August 2006 (UTC)

Except the evidence, at least with regards to MC1R, suggests that is not the case. However the exciting discovery of SLC24A5 and its association with human skin colour, may provide evidence for positive selection for vitamin D production. Time will tell. Rockpocket 06:27, 7 August 2006 (UTC)

evolution of snoring

Given that snoring makes it easier for lions to eat you when you are asleep. Is it true that Africans do not snore? Ohanian 22:02, 6 August 2006 (UTC)

that is the smartest thing I've seen all week

Why does snoring make it easier for lions? 8-?--Light current 01:27, 7 August 2006 (UTC)

Lions have big ears to find you when you make noise. This does not help them to eat you, though. There are lions in less than 20% of Africa. Now we are looking for a testimony about real africans really snoring like you and me. --DLL 19:35, 7 August 2006 (UTC)

Having lived in Africa for a number of years, where i attended a boarding school. I can confirm Africans do snore. Loudly. Rockpocket 05:35, 8 August 2006 (UTC)

Northern Europeans would freeze to death if they had no protection against the cold, such as houses. Africans don't need houses against the cold (well, not as much anyway), but they do help against lions. So they can snore for the same reason we can survive without fur. We have different means - our ability to change our environment (ie build houses). DirkvdM 08:32, 8 August 2006 (UTC)

Porosity vs. Heat Capacity

How does the porosity of an object relate to its thermal capacity? For example, does a material with more pores allow more heat to pass through it than an object with fewer pores?

Depends probably on the comparative thermal conductivities of the pores (air) and the material of the object. BTW did you read your own question? 1st part makes no sense.--Light current 01:31, 7 August 2006 (UTC)

Oops...

Persykology

What's the deal with that strong desire some people have, on encountering an extremely cute and appealing organism, to kill it? I know that sometimes when I see a cute animal I want to squeeze it to death. What's with that? Also, why do people find baby animals appealing anyway? I suppose it would have been an evolutionary advantage to our ancestors as part of the domestication process, as anyone finding an abandoned wolf cub, finding it cute and raising it would have an obvious advantage when the bugger grows up, eh? Try and answer my first question first because you may have forgotten about it, I know many people who would have :P Vitriol 23:03, 6 August 2006 (UTC)

I'm sorry, but I have never heard of a desire to kill cute, appealing things as a common response. As for why baby animals are appealing, see cuteness. --Ginkgo100 ^{talk · contribs · e@} 20:47, 7 August 2006 (UTC)

I'm sure some people would know what I'm talking about. Or maybe I'm just nuts. Vitriol 23:09, 7 August 2006 (UTC)

I'd say that when people remark that they want to hug/squeeze something 'to death', they're not actually serious. It's more of an indication of how cute something is. --Con 23:26, 7 August 2006 (UTC)

O RLY? I am nuts! Vitriol 23:37, 7 August 2006 (UTC)

Welcome to the club! (Although my nutness lies in other areas (and why doesn't my spellchecker protest against the word 'nutness'?))

Btw, I love baby crocs. They have this unique combination of cuteness and a vicious appearance. DirkvdM 08:40, 8 August 2006 (UTC)

I don't think you're nuts, Vitriol - I've felt it too, and know several people who have - I reckon it manifests in such phrases as 'I could just eat her up', and 'I love her to pieces' - it's like cuddling the object of your affections isn't enough - you want to squeeze! There's a scene in Punch Drunk Love where the lovers tell each other they want to smash each other's faces in with mallets etc - but it's extremely tender; they're saying kissing each other just won't suffice to express the fierceness of their love. Well, that's what I think anywayAdambrowne666 01:40, 10 August 2006 (UTC)

natural hydrogyn production

Is the Earth's atmosphere filling up whith hydrogyn? If so at what rate?

...should it be? Vitriol 23:49, 6 August 2006 (UTC)

Why would you think that? I can't think of anything that naturally releases hydrogen gas. —Keenan Pepper 00:35, 7 August 2006 (UTC)

YOUR MUM! Hahahahahahaha Vitriol 00:36, 7 August 2006 (UTC)

Humans do not release hydrogen.(at least not in large quantities). Also, this page is not for stupidly childish comments like that above.8-(--Light current 01:19, 7 August 2006 (UTC)

Actually, the bacteria in the gut release methane (and hydrogen sulfide and thiols, which are responsible for the smell), and according to Anaerobic digestion#By-products of anaerobic digestion, there's some hydrogen in the mixture too (although there's no reference, so I can't follow it up). —Keenan Pepper 02:20, 7 August 2006 (UTC)

Yeah but when you set fire to farts, its the methane that ignites- is it not?--Light current 02:25, 7 August 2006 (UTC)

No, hydrogen in the atmosphere is excited by ultraviolet light to react with oxygen and form water. Hence it is not accumulating. In addition, like helium, hydorgen is so light in its pure form that the portion that manages to rises to the top of the atmosphere without reacting with oxygen is slowly blown into space by the solar wind. Even without an oxygen atmosphere, a planet with the mass of Earth at our distance from the sun would not be able to accumulate much free hydrogen because the solar wind would blow it all away. Dragons flight 06:25, 7 August 2006 (UTC)

Some bacteria that live in the GI tract do produce hydrogen. That's the basis of an easy test for lactose intolerance. DMacks 09:28, 7 August 2006 (UTC)

August 7

Megawatt Battery

Is it possible to build a rechargable battery that could hold a Megawatt or more?--67.126.143.196 00:09, 7 August 2006 (UTC)

EDIT'D because someone mistakenly put their question here, eh? Vitriol 00:50, 7 August 2006 (UTC)

A megawatt is a measure of power and you cant hold power in a battery. Howver if you mean megajoule which would give 1 MW for one second, then it should be possible by connecting lots of small batteries together. Why would you want to do such a thing anyway?--Light current 01:05, 7 August 2006 (UTC)

It would have many uses, such as for a rail gun or coil gun. StuRat 06:52, 7 August 2006 (UTC)

In that case you need large HV capacitors (the ultimate rechargeable) rather than batteries. 8-)--Light current 11:51, 7 August 2006 (UTC)

They built a 40 megawatt NiCd battery in Alaska in 2003. See http://www.mpoweruk.com/history.htm#2003. --Heron 20:48, 7 August 2006 (UTC)

1 million joules is easily held in a typical car battery, and is a relatively small number compared to what's typically used in commercial UPS applications. A common large scale UPS configuration will have 200 or more batteries, together capable of discharging up to 1MW each second, for up to 15 minutes, amounting to almost 1GJ of energy. Did you mean for it to be portable? --Jmeden2000 21:46, 7 August 2006 (UTC)

And how large is this GJ battery pack?--Light current 02:10, 8 August 2006 (UTC)

Imagine a whole room full of batteries, and then double it :-) --Jmeden2000 15:16, 8 August 2006 (UTC)

Persactly! That Y I suggested HV capacitors.--Light current 15:22, 8 August 2006 (UTC)

Too bad there isn,t one the size of a car but thanks alot for the help.

Ahh, now I see where youre coming from! What about fuel cells?--Light current 19:23, 8 August 2006 (UTC)

Wouldnt you need a bunch of fuel cells to produce 1 Million Joules? A car sized battery or device that could produce power in the millions of joules would be perfect for spacecraft, using possibly Ion Thrusters or some sort of electrical thruster.

Dont ask me -- look at the page! 8-)--Light current 21:23, 8 August 2006 (UTC)

Septic System

I can't seem to grasp the workings of a septic system

If I use DIAL soap, and dial soap is anti-bacterial, as is most of the laundry detergents on the market, doesn't that cause the septic system to shut down?

Why aren't there enough "bacteria" in the human by-products going into a septic tank so that you don't have to add an additive of more bacteria?

Thanks

   Larry

You shouldn't have to add any kind of additives to a properly-functioning septic system. The enzyme treatments and other things sold to be used in septic systems are not really necessary. The things that cause a septic system to fail are pretty simple mechanical failures: Over time, the indigestible solids will accumulate in two places- as a floating scum layer, and as solids that sink to the bottom. Given enough time the scum layer can become very thick, and the solid layer at the bottom can also become very thick, and so the 'working space' below the scum layer and above the solids becomes too thin to be effective.

If the baffles fail, then it's possible for the scum layer to drain down into the drain field, where it may plug up the orifices in the laterals, severely affecting the ability of the drain field to function. So having the system checked, inspected, and pumped out every five to ten years will greatly help it to keep working. You don't say if it's a gravity system or a pressurized system; gravity systems tend to fail over time because the flow rate through the drain field is very low. It's not hard to inspect a septic system, doing a google search will point you in the right direction; a couple simple tools and some time and you will be able to check your system out.

I almost forgot to answer your original question: Yes, excessive use of antibacterial products may cause harm to your septic system. The key words are 'excessive' and 'may'. Normal use seems to be fine, just don't go overboard. For additional reading, see pages like this one .71.112.133.208 04:00, 7 August 2006 (UTC)

You don't need to add bacteria because they are quite capable of doing that themselves through reproduction. And unless you throw in huge amounts of antibacteria, they shouldn't be hurt too much. Bacteria can take quite a beating. DirkvdM 08:47, 8 August 2006 (UTC)

hang-drying clothes indoors with A/C

If I have my air conditioner on, and I hang up my wet clothes indoors to dry, I figure I'm essentially asking the A/C to do the work that the dryer would otherwise be doing, and in theory it might take the same amount of energy. But what about in practice? Considering the different technologies and drying times, would one process (A/C vs. dryer) would use more energy than the other, or would they be about the same? Thanks. --Allen 00:48, 7 August 2006 (UTC)

I don't know if this is any better than just having a fan blowing on the clothes.

It is better, becuase an A/C (or a dehumidifier) will remove the moisture from the air leading to quicker drying. A fan would just tend to make the air more humid, reducing its drying potential. 8-)--Light current 14:31, 7 August 2006 (UTC)

How does a fan make the air more humid? DirkvdM 08:50, 8 August 2006 (UTC)

By transferring the water from the wet clothes into the air of course!--Light current 11:26, 8 August 2006 (UTC)

The primary function of an airconditioner is to cool the air, which doesn't help in this case. If it's so hot outside that you need an airconditioner, then why not hang your clothes outside? DirkvdM 08:50, 8 August 2006 (UTC)

It could be raining outside but hot inside 8-)--Light current 13:23, 8 August 2006 (UTC)

The action of cooling the air also dehumidifies it as the water condenses on the cooling coils!--Light current 11:48, 8 August 2006 (UTC)

Exactly, Light current. It often rains in the afternoon in Tennessee, even on the hottest days. So if I hang my clothes on indoor drying racks instead of using the dryer, I'm curious to know whether I'm conserving energy or just inconveniencing myself. --Allen 04:03, 9 August 2006 (UTC)

Depends on the comparative efficiencies of the AC unit and the drier. 8-) You dont say what sort of drier it is. --Light current 11:01, 9 August 2006 (UTC)

Hot mirrors

Today it was rather warm (say 25 celsius) and humid. This afternoon, I was standing about 0.7 m in front of some large mirrors for a long time (playing a gig actually). I noticed that it felt considerably hotter infront of these mirrors than in other parts of the room or even outside. I initially thought it was the IR from the surroundings reflecting but since IR cant travel thro normal glass, I remain puzzled. 8-? Any suggestions as to the cause of this phenomenon? --Light current 01:13, 7 August 2006 (UTC)

See solar cooker. Rangek 01:23, 7 August 2006 (UTC)

Yeah thanks for that, but those cookers use no glass. I was cooking in front of glass! Also, it wasnt sunny-- complete cloud cover.--Light current 01:37, 7 August 2006 (UTC)

No glass? Read a little more closely. Almost all of them are made of glass/mirrors. Even when it is completely cloudy there is still lots of solar radiation reaching the surface. Rangek 02:04, 7 August 2006 (UTC)

Yeah OK, but theyre using high intensity visible light energy from the sun. THere was not much light in the room and IR cant pass thro the glass to be reflected by the silvering on the back of the mirrors. Mirrors can reflect IR if they are front silvered (or just a shiny bit of metal)--Light current 02:15, 7 August 2006 (UTC)

So were talking solar radiation that can:

• pass thro clouds,
• pass thro the glass,
• get reflected from the silvering,
• pass thro the glass again and
• irradiate me on my back so I feel hotter.

Is that what youre saying? If so, what sort of radiation would that be? Would it be the near IR, and if so can you feel it as heat?--Light current 13:15, 7 August 2006 (UTC)

Is this a sort of space blanket effect?

Can I ask where it is you live that it's only 25 degrees Celsius? Southern hemisphere? Iceland? Seems most of the northern hemisphere is in the throes of a long-lasting heat wave. Today is a cool day where I'm from and it's supposed to hit about 30 Celsius. --Ginkgo100 ^{talk · contribs · e@} 20:50, 7 August 2006 (UTC)

The northern hemisphere is slightly bigger than where you live. :) The heat wave in Europe is long over. DirkvdM 08:56, 8 August 2006 (UTC)

Okay. The last I had heard, Europe was still suffering. The veiled insult was unnecessary. --Ginkgo100 ^{talk · contribs · e@} 18:07, 9 August 2006 (UTC)

Its the UK. And maybe it was 27 or 28 Celsius. I didnt have a thermometer handy!--Light current 01:42, 8 August 2006 (UTC)

I suspect you are thinking of UV not easily passing through glass. --Seejyb 22:15, 7 August 2006 (UTC)

No Im thinking of IR. UV can pass thro glass I believe. Think of greenhouses! 8-|--Light current 01:42, 8 August 2006 (UTC)

No, UV is blocked by most common glass. That is why it is nearly impossible to get a sun burn in a car with the windows up and why quartz cuvettes are used for UV spectroscopy. See Ultraviolet-visible spectroscopy#Ultraviolet-visible spectrophotometer. Rangek 03:14, 8 August 2006 (UTC)

Ahh it must be visible light that passes thro glass in a greenhouse then and gets converted ito far infra red?--Light current 03:24, 8 August 2006 (UTC)

Actually, it turns out that has very little to do with how greenhouses work. See greenhouse. It turns out it isn't so much that the greenhouse is trapping the radiation, but it is just not letting the hot air drift away. Rangek 18:29, 8 August 2006 (UTC)

And the hot air being above absolute zero emits radiation- yes? seeWein's laws. If this radiation can escape thro the glass then the heat will not be retained. What is the wavelength of the radiation at 300 K? and can it pass thro greenhouse glass -- that is the question! 8-|--Light current 19:44, 8 August 2006 (UTC)

Any chance it has nothing to do with the mirrors? Was there anything else about that spot? Maybe less air current (the back of a room?). And you were doing a gig, so were there any lamps pointing at you (although I doubt you would have missed that option). DirkvdM 08:56, 8 August 2006 (UTC)

Dont think so. There were 3 lamps each of 60W spaced at about 1.5 m between the mirrors. As this power was only equivalent to that generated by about two persons, I decided that this could be ignored. It felt like a few hundred watts on my back. Also i was standing in the center of the mirror (not in front of any of the lamps). Also it felt like radiation, not warm air.--Light current 11:33, 8 August 2006 (UTC)

Some confusion here. Glass normally absorbs UV; Reflects a lot of IR (feel the reflection from an ordinary glass pane when you shine an IR light on it; maybe you would have felt the same heat standing in front of unmirrored glass, especially if you were wearing black). But definitely transmits some IR. Herschel discovered IR by transmission through an ordinary glass prism - there was something measurably hot coming through beyond the red end of the spectrum, and the heat he measured was more than that from the red part coming though the glass of the prism. Most optical cables use IR for transmission - once the light is in the glass fiber, with not as much being absorbed as shorter wavelengths would, it is tranmitted better than visible or UV light of the same initial energy. If you put an IR lamp in front of an ordinary glass pane you can feel the reflection of heat. "Ordinary" 35mm cameras can take quite effective IR pictures with "ordinary light" lenses, using IR sensitive film - the focus has to be compensated for, but some lenses have IR markings on them. --Seejyb 01:13, 9 August 2006 (UTC)

OK this makes the most sense yet. So I was getting about twice the radiation that I would have got if there had been no mirror and just the brick wall? Hmm -- interesting!--Light current 03:01, 9 August 2006 (UTC)

Plane on conveyer

Why there's no article about that famous plane on conveyer that some mistakingly claim won't take off? It was twice on Straight Dope with two conflicting answers on 03.03.2006 and 03.04.2006 and that alone makes it notable. By the way, the plane will fly off with wheels sliding all the way, contrary to the second article :)

The two articles are [4] and [5]. I'd like to take the position that the second article is correct: the conveyor belt can be rigged so that the plane does not take off. Just as the plane starts moving forward, you speed up the belt so that the plane nudges back where it was one second ago. Keep doing that, and you get a balance where the friction of the wheels causes a backwards force that exactly balances the forward force of the plane's engines. Zero net force, no movement. Weregerbil 07:32, 7 August 2006 (UTC)

But if lift is generated by air moving over the areofoils, and there is no air moving over the areofoils due to the wings not moving through the air, how can the plane take off? --130.161.182.112 14:29, 7 August 2006 (UTC)

Right. In one interpretation the question can be reduced to: Will the plane pick up enough absolute speed? If we manage to keep the plane in place by increasing the belt speed more and more, the wheels will also spin very fast and eventually generate so much heat through friction that the axle melts, or else the wheels come apart by the centrifugal forces. If we assume idealized components not subject to such mundane effects, you have to be very precise about which parts of physics are still operational. If the plane remains stationary while the belt moves extremely fast, the belt will drag air along and cause so much wind that the plane still gets sufficient lift. And so on ...  --Lambiam^Talk 16:23, 7 August 2006 (UTC)

If we have a real plane its engines have finite maximum power, so at some point the speed of the belt stabilizes and significant air flow from the belt doesn't necessarily need to happen. Or maybe it will. This could be one of those things that needs to be tried in practice. How do you go about suggesting things to the MythBusters? :-) And no wimping out by using a small model plane. Weregerbil 16:43, 7 August 2006 (UTC)

Lift requires that the plane be moving in reference to the air, not the ground. --mboverload@ 00:31, 8 August 2006 (UTC):

Echo mboverload--Light current 03:11, 8 August 2006 (UTC)

I've seen this question beat to death dozens of time on the internet. I like this discussion the best at physicsforums [6]. — [Mac Davis] (talk)

float glass

What is float glass? And what is the russian translation for it? Inna.

Our page entitled Float glass is probably a good place to learn what it is. DMacks 05:57, 7 August 2006 (UTC)

I suspect that in Russian you can use полированное стекло ("polished glass") or for an audience of experts simply флоат-стекло. --Lambiam^Talk 08:26, 7 August 2006 (UTC)

Photons

Photons have no mass, yet they can exert radiation pressure(mass-mass interaction involving change in momentum?

Yes. Radiation pressure --GangofOne 06:30, 7 August 2006 (UTC)

Yes. While they do not have any mass, they nevertheless have momentum (given by h/λ, where h is the Planck Constant and λ is the wavelength of the photon).

>>This one took me eight years to figure out, 'And yes Photons at times do indeed have mass', refered to as rest mass, but there is really no difference, it's just the termanology. I will give you a hint; photons as electromagnetic energy have no mass, and can even travel through two slits at the same time ( ie. the dual slit experiment). Yet durring an interaction (such as striking a white or black piece of paper), like an inferometer their velocity is no longer the speed of light, and they are no longer electormagnetic rediation but a particle that has mass aquired from the conservation of evergy. This is only a hint, It seems to be from my experience a close held secret, at least for undergraduates. Other clues in space time energy fluxuations cause mass to "pop" out of energy, then the mass transfers back to energy. Also in a clyclatron durring a collision there are particles with mass that have a spiral trajectory in an electromagnetic field, but are short lived before they "disaper or transform into energy." It goes both ways Also They Do Have Mass When Transfering Momentum!.--68.189.46.87 12:52, 7 August 2006 (UTC)aaron.

When you talk about the rest mass of the photon I assume you mean (hf)/c² (or p/c). I don't believe that is of any consequence in this question, although a good means of explaining where photons get their momentum from.

Yes the rest mass is relative to this question, It is the mass of the photon when it exist as a particle!Durring an interaction. The Photon acctually has the mass of the rest mass, for a brief period of interation! aaron--68.189.46.87 14:02, 7 August 2006 (UTC)--68.189.46.87 14:02, 7 August 2006 (UTC)

>>>Do I need to repeat the old adage of photons at times behave as electromagnetic radiation and at other times as a particle. Think about it, I believe I have explaned it, if you don't understand, quit trying>>>Photons durring interactions are particles with a mass equal to their rest mass. Look up the interaction tables! aaron--68.189.46.87 14:22, 7 August 2006 (UTC)

When I say I don't think it's of any consequence, the question didn't ask for the mechanisms by which momentum was exchanged. The effects are described well enough by whoever gave the second answer. I can assure you I do understand wave/particle duality, I did do a PhD in quantum computing.

Sorry but I felt that the mechanisms by which momentum was exchanged was relavent to the understanding of the original question, in my opinion. I trust you opinion and your understanding, but since the question stated that photons have no mass in my opinion it was relative. Again Im sorry. aaron--68.189.46.87 15:01, 7 August 2006 (UTC)

That's quite alright. I generally hesitate to use the term 'mass of a photon' because, while they may have mass during an interaction, it is only for a very short time and time and energy/mass are non-commuting variables.

What about reading our article Photon? Photons have energy and therefore also have mass in the usual sense of gravitational mass. The usual meaning of "rest mass" is the mass at zero speed, which is meaningless for photons, but using the formula for relating (relativistic) mass with rest mass, you find a rest mass for photons that is zero, zilch, nada. --Lambiam^Talk 16:33, 7 August 2006 (UTC)

Yes you are correct the rest mass of a photon is a misnomer, since it can never be at rest, it is an old term for it's mass at non relativistic speeds. But durring interactions when it is a particle it does have mass, read the article photon and you will find an approximation for a photon's mass. Not rest mass but mass --68.189.46.87 17:50, 7 August 2006 (UTC)aaron

The term 'rest mass of a photon' is a useful (if rather antiquated) terminology for explaining radiation pressure. Mathematically it comes from the energy of a photon, E=hf and E=mc² and gives m=(hf)/c²

>>Yes mathematically, but the truth of the matter is that it is a particle for a brief period of time durring the interaction, it is a actually a partical with mass that is not traveling at the speed of light; and this does come from the energy of the photon, which is transformed into mass. Which may or may not transforme back to pure energy with no mass, travaling at the speed of light--Aaron hart 07:22, 8 August 2006 (UTC)

See optical tweezers. -- SGBailey 22:28, 11 August 2006 (UTC)

Black holes

How come black holes have two beams of energy?

The polar jets or relativistic jets don't come from the black hole itself, but rather from the accretion disk around a black hole. StuRat 06:46, 7 August 2006 (UTC)

But to answer the question, nobody knows Philc _T^E_C^I 15:12, 7 August 2006 (UTC)

large low density rock?

I have found a rock that is 1235 cm^3 and weighs only 148g, this gives it a density of .12g/cm^3. Is this just a large size of unusual pumace. It has a honycomb sturcture on the outside, but under an ultraviolet light, there is a distinct differece (as in two distinct layers, like the bottom side was heated to a much higer temp. than the top. Also on the top there is a bump with the lighter grey comming from the tip to the bump, and then it darkens,) I can see how the heat has effected it, turning it a lighter grey?? It is black to dark grey any coments?? aaron--68.189.46.87 14:38, 7 August 2006 (UTC)

Could it be a chunk of an artificial building material, like foamed slag concrete, pumice concrete, or expanded shale? Femto 15:13, 7 August 2006 (UTC)

>>No it was found out in the woods on the top of a hill, It is definatly all natural, Thanks for the advise though.

Pumice is a good idea. --DLL 19:28, 7 August 2006 (UTC)

The density of Pumice can vary quite a bit but I've never heard of a sample that light before. The range is usually somewhere between 0.6g/cm³ and 1.2g/cm³. Where do you live? Do you have a picture of the rock that you could post? --Nebular110 19:33, 7 August 2006 (UTC)

Honeycomb structure? Is it a nest of somesort? Wasps make very light nests... Isopropyl 00:00, 8 August 2006 (UTC)

Did you find this in the debris field of Space Shuttle Columbia? --Lambiam^Talk 02:09, 8 August 2006 (UTC)

Yes I can post a picture, if I can find out how, and no it is not a nest of somesort, it's almost like a carbon structure, I will attempt to upload a photo, if unsucessful I will post my email and I will send it to you. aaron--68.189.45.241 03:32, 8 August 2006 (UTC)

This rock was found in Shasta County, ca. on the top of a hill, and yes the density is aporxamatly .12g/cm^3 I believe this to be rare, Please reply--Aaron hart 07:02, 8 August 2006 (UTC)aaron

It looks like scoria, but I think that would typically have a higher density; I don't know the range. Tuff can be very light, but usually doesn't look so rough. I think that also applies to cinder, which however can be so light (according to our article) that it even floats on water, so that aspect fits. --Lambiam^Talk 07:57, 8 August 2006 (UTC)

Looks like the carbon left over after the dehydration of a sugar, can that happen naturally? Philc _T^E_C^I 12:21, 8 August 2006 (UTC)

Looks like a large piece of coke (coal with all the hydrocarbons removed leaving only pure carbon) Can you see any pores in it. Cant tell from photo--Light current 13:46, 8 August 2006 (UTC)

Could it possibly be extra terrestrial?--Light current 14:06, 8 August 2006 (UTC)

According to [7] there are no lightweight meteorites. Femto 15:13, 8 August 2006 (UTC)

Aaron, forgive me if I sound patronizing, but are you sure you got the weight right? Any silicate is going to have a local density of ~2 g/cm^3. Pumice and other volcanic rocks can lower their bulk density by incorporating air pockets and voids, but your pictures shows no evidence of voids intersecting the surface. Similarly, with the dimensions shown, it couldn't have more than a few millimeter thick shell of silicate, in which case I'd expect it would have been so fragile that it would long ago have broken. At less than 200 g, even a decent wind should be able to blow it around and smash up the thing. If it really has the density you say, my only conclusion is that it can't be a rock, and is likely to be synthetic. What is the texture like? Is it rough? Squishy? My guess might be some sort of weathered packing foam. Dragons flight 14:45, 8 August 2006 (UTC) >> Yes the mass not the weight is 148g. And I really doubt that it is packing foam, I guess I will have to take it to the local colledge, and then I will let you know. its tecture is very hard and brittle, pices come off of it every time I pick it up.--Aaron hart 14:51, 8 August 2006 (UTC) but you may be correct, we shall see, maybe I found something rare?? >>Forgive me I checked very accuratly and the mass is 147.2g--Aaron hart 15:01, 8 August 2006 (UTC) also it is full or pores, and I can tell that the crust is more than a few mm thick. But it may be synthetic, just seems ood to find it on top of a hill in the woods.--Aaron hart 15:04, 8 August 2006 (UTC)

Strange. Did you break it open to see what the inside is like? Is it mostly hollow maybe? Were there other specimens similar in the area or did it look totally out of place on the top of the hill? --Nebular110 17:43, 8 August 2006 (UTC)

It would be good if it was a new stone; they could call it Hartstone! smurrayinchester^{(User), (Talk)} 21:48, 8 August 2006 (UTC)

Two Cars in a Head-On Collision

In my game PGR3 (in which I find the physics very unrealistic) I was going to run in to my brother in a head on collision. I was going 207 mph and he was going 183 mph. With the physics like they are, the cars collided and not a whole lot happened. My question is, how much power would that exert? I'm not real smart about Physics, but I remember the Law of Conservation of Energy and that the energy is still there, you just don't see it(?) and all the energy those cars had were almost immediately gone. I hope someone understands my rambling here. Thanks. schyler 12:04, 7 August 2006 (UTC)

Without knowing the game I guess they may be simulating the energy absorbing features of the cars and they just crumple up. THe energy is used in deforming the metal, creating sound etc but all the enrergy finally ends up as heat if both cars are at rest. THe kinetic energy of each car is 0.5 mv^2, so you could work out how much energy was dissipated in the crash (assuming both cars are at rest afterwards).--Light current 13:23, 7 August 2006 (UTC)

Also unlike Kenetic Energy the momentum for the two cars before and after is absolutly conserved, Kinetic Energy is also conserved but takes on other form. But The momentum before and after the collision are the same. Momentum=mass*velocity so if they came together at a complete rest, without one or the other moving backwards, the masses of the two cars must be different, in other words v1m1=v2m2. In a system Kinetic energy is transformed into deformation, heat, sound etc. and as stated earler end up as heat. But momentum is conserved without transformation into other forms. Although after both cars come to a rest there is frictional momentum that is transformed to the earth. aaron--68.189.46.87 13:33, 7 August 2006 (UTC)

Energy of deformation is not all dissipated through heat. It takes work to "lift" the metal into its new position just as it would to lift a weight through gravity or push a weight against a spring. Heat and strain cause most of these springs to fail, but a small fraction of this "spring potential" remains stored in the twisted metal.165.228.98.213 (talk) 02:32, 12 May 2008 (UTC)snn 12:30, 7 May 2008 (UTC)

You are right about the shoddy physics, especially with respect to collisions. Most driving games don't bother with them since its little or no fun to watch a car turn into 'not a car' and then require the player to start over. The question I think you should be asking (since you probably know that you are just dealing with two huge quantities of kinetic energy) is 'where would that energy go to?' Objects collide and one of two things happen to the kinetic energy, a) An elastic collision where kinetic energy is conserved and b) an inelastic collision where kinetic energy is converted into internal energies. Since cars are quite dynamic there would be a combination of these two as the various metal and plastic bits met head on. Much of the energy is 'gone' into another form such as heat, as the metal in each chassis takes on a dramatically different form. Some energy may come back kinetically and one or both cars will continue moving after the collision, or (more likely) many small bits from each would keep moving. --Jmeden2000 21:17, 7 August 2006 (UTC)

It's not a physics answer, but the reason why the cars don't suffer a whole lot of damage/body deformation in the game is because the car manufacturers, who licence their cars for use in the game, don't want their brand associated with mangled wreckage, etc. (or so rumour has it). On the other hand, a game like FlatOut which uses generic unbranded cars can mangle the bodywork all it likes. Sum0 23:33, 7 August 2006 (UTC)

>> Also in deformation of the cars there energy put into the deformation, but also this creates a large amount of heat, The Physics may be shoddy, but sugesting an elastic collision, with cars, come on now! aaron--Aaron hart 07:14, 8 August 2006 (UTC)

Did you even read my entire reply? Just curious, i know i tend to ramble sometimes but i did get everything in there i intended to --Jmeden2000 15:12, 8 August 2006 (UTC)

>>A perfectly elastic collision is defined as one in which there is no loss of kinetic energy in the collision. An inelastic collision is one in which part of the kinetic energy is changed to some other form of energy in the collision. Any macroscopic collision between objects will convert some of the kinetic energy into internal energy and other forms of energy, so no large scale impacts (ie larger than atoms, or molecules); are perfectly elastic--Aaron hart 07:04, 9 August 2006 (UTC) I do remember a little from college. For a possible elastic collision occuring, solids from the car body, must vaprorize into a gas, then it is possible for these two gasses to have a perfectly elastic collision, But this would be quiet neglagable, and would not even beging to be able to be calculated!--Aaron hart 07:15, 9 August 2006 (UTC)

biology

hi im a student of psg biotech....can anyone say how to estimate the density of spores like vegetative spores or especially the spores of bacilus subtilis.....give some detailed explanations....

Sounds like homework. I'd try a PubMed search for bacilus subtilis spore density and follow the protocols given in the articles. -- Scientizzle 18:15, 7 August 2006 (UTC)

I would use a hemocytometer myself.Tuckerekcut 21:02, 7 August 2006 (UTC)

Microwaves Lose Power After 15 Minutes Use?

In the microwave article, it says that after 15 minutes of use, the power of the microwave drops off - is this true? What is the cause? The text in question can be found at the bottom of the section which this link leads; Microwave oven#Uneven heating, deliberate and not

It it is true, which it may well be, then it is a mechanical effect of the microwave oven, not with the microwaves themselves. --198.125.178.207 18:51, 7 August 2006 (UTC)

The magnetron gets less efficient as it heats up. There is a link in the microwave article that used to explain this, but it is now a dead link. --Heron 20:38, 7 August 2006 (UTC)

Yes, and not necessarily after 15 minutes, I would assume. --Proficient 12:09, 10 August 2006 (UTC)

Pocket PC emulator

Can I run Pocket PC programs on Microsoft Windows using an emulator? -- Toytoy 14:21, 7 August 2006 (UTC)

I think that the answer is yes, that's why emulator design is for. Now, does such emulator exist, and did you try any search engine with the terms of your question ? -- DLL ^{.. T} 18:49, 8 August 2006 (UTC)

I believe that there is a Pocket-PC edition of Microsoft Visual Studio, which includes exactly such an emulator, as well as a Visual C++, Visual Basic, and other Microsoft programming environments/compilers for pocket-pc's. Are you a software developer, or just an end-user trying to use a PDA tool on your desktop? If the latter is the case, you may find a workaround using conventional desktop software for the same task. Nimur 19:39, 8 August 2006 (UTC)

I want to run MetrO on my Windows computer. I don't know why this program does not have a Windows version. -- Toytoy 05:55, 10 August 2006 (UTC)

A warm sun

Why does the sun feel warm when youre exposed to it? Its a serious question.--Light current 14:27, 7 August 2006 (UTC)

All electromagnetic radiation (including light) is just a form of energy. When the light hits your skin, some of it is reflected and some is absorbed. The energy in the light which is absorbed has to go somewhere (see Conservation of energy) and becomes heat energy. All light, natural and artificial, will transfer some heat energy to a surface it hits (as long as that surface isn't perfectly reflectant). -- Plutor 14:38, 7 August 2006 (UTC)

So you can get warm just from visible light?--Light current 14:40, 7 August 2006 (UTC)

>>yes; aaron--68.189.46.87 14:49, 7 August 2006 (UTC)

OK thanks for shedding some light on the problem! 8-))--Light current 14:51, 7 August 2006 (UTC)

So do your eyes get warm when you look at things? I thought it was only glassblowers who got cataracts. 8-)--Light current 21:16, 8 August 2006 (UTC)

The sun is just a big firebrand. Visible light must take a very little part in the heating. Non-visible radiation (infra red) is also absorbed by the skin and diffuses to the body, it heats more accurately. --DLL 19:24, 7 August 2006 (UTC)

What do you mean by firebrand?--Light current 02:23, 8 August 2006 (UTC)

Well, he probably doesn't mean that the sun is made up of a bunch of cartoon characters, or that the sun is a burning ball of fighter planes so it's safe to assume maybe he meant that the sun is something that's on fire, like a giant bunch of burning wood.

Funny, 'brand' is Dutch for fire. What is the etymology of the word? DirkvdM 09:17, 8 August 2006 (UTC)

According to Webster's and Livestock branding, brand had meanings of hot stick/torch/sword in Middle English. I think I've seen -brand being used in sword names in the works of Tolkien as well. --Kjoonlee 13:56, 8 August 2006 (UTC)

I fear this thread is diverging rapidly--Light current 13:27, 8 August 2006 (UTC)

Sorry, firebrand was a bad googletranslatetool try. Let's say ember : hot burning wood. I meant that it is not the red that heats in it. -- DLL ^{.. T} 18:44, 8 August 2006 (UTC)

Ember is also a sort of bad translation. The sun's heat and light come from nuclear fusion, not combustion. Although it looks red, this is because the plasma is hot and acts as a blackbody, radiating energy in the visible spectrum and other wavelengths as well. You feel warm because you absorb some of the radiation in ALL wavelengths (albeit, more from some spectral elements than others). Ultra-violet radiation contributes to your tan (a bio-chemical process); infrared directly heats you, and visible light does contribute some heat as well. However, the sun is not an ember, or a firebrand - it is hot plasma of mostly hydrogen and helium undergoing thermonuclear reactions. Nimur 19:45, 8 August 2006 (UTC)

Ahh a sensible answer at last- THanks!--Light current 19:55, 8 August 2006 (UTC)

and not once did anyone mention seagulls

What the **"£$** have seagulls got to do with anything?--Light current 13:25, 9 August 2006 (UTC)

>> I thought the first two replies were sensible, and ansured your question, Not to make this thread any worse!--Aaron hart 07:24, 9 August 2006 (UTC)

Yes youre quite right Aaron. The first two replies were useful. Thanks 8-)--Light current 13:23, 9 August 2006 (UTC)

nursing

Moved to Wikipedia:Reference_desk/Misc

plz i am in ghana and did go to school but could not complete my highschool.but now i want to school in the nursing field at canada .so plz i will like to know how it will go and the steps i will be taking.i dont have any relations there but i want to school there and pursue my degree thank you

I think this question would have better chances on the 'Misc' page.--Light current 16:18, 7 August 2006 (UTC)

with spelling and grammar like that youre not going anywhere =P -PitchBlack

I could say that you meant to say "With spelling and grammar like that you're not going anywhere." but that would be unprofessional. Sum0 10:18, 9 August 2006 (UTC)

But correct! 8-)--Light current 13:27, 9 August 2006 (UTC)

lol! --Proficient 12:14, 10 August 2006 (UTC)

GPS precision

I know that GPS receivers usually report an estimate of the accuracy of the readings they provide, but I'm curious about their precision. Most give readings with seven digits, like N12° 34.567 W12° 34.567. How can you figure out the distance between that point and the very near one at say N12° 34.568 W12° 34.567? The distance between any two longitude lines is going to vary depending on how far you are from the equator, right? Is there any website that will calculate the distance between any two lat/long coordinates? 148.177.1.219 18:53, 7 August 2006 (UTC)

Use some version of the way you find the distance between two points on a Cartesian coordinate plane. I don't know how. — [Mac Davis] (talk)

A simple Google search on latitude distance came up with http://jan.ucc.nau.edu/~cvm/latlongdist.html as the first entry. Skapur 20:09, 7 August 2006 (UTC)

The circumference of the Earth is about 40.000 km or 360x60 = 21600 minute. So 1' = 1.85 km. That goes for all lattitudes and for longitude at the equator (at least if Earth were a perfect sphere, which it isn't, but I'm only giving an estimate here). For any other longitude, you have to multiply by the cos of the (mean) longitude. Luckily, you save me that trouble because the longitudes are the same. And consequently, I don't need Pythagoras either (the square root of the sum of the squares of the two distances). So the answer to your example is 34.568 - 34.567 x 1.85 km = 1.85 m. As a rule of thumb, 1° latitude is about 100 km (actually 111 km) and the same goes for longitude at the equator. At 60° north or south (roughly Scotland and New South Wales) it's half that. DirkvdM 09:47, 8 August 2006 (UTC)

See the Great-circle distance article for details about calculating distances between points on a sphere along its surface. DMacks 19:48, 9 August 2006 (UTC)

Scientist famous for numbering all correspondence and papers

I remember hearing about some scientist, I believe he was a physicist, who numbered pretty much everything he wrote for several decades. From journal articles to letters to friends. The numbering scheme was his three initials followed by a number (I think it was 4 digits).

Can anyone remember his name for me? Thanks.

Doesn't everyone do that? Notinasnaid 19:46, 7 August 2006 (UTC)

A computer scientist who did that was Edsger Wybe Dijkstra. --Lambiam^Talk 02:12, 8 August 2006 (UTC)

If I did that here, 4 digits wouldn't suffice. DirkvdM 09:54, 8 August 2006 (UTC)

I think there's something there for all of us to think about, Dirk.  :--) JackofOz 12:03, 8 August 2006 (UTC)

It could do if the four digits were not decimal. hexa would'nt suffice ; but you may create any base (I have my eyes on the 'insert' template when editing this : 0123...ABC...ĕØΘЫɱ). -- DLL ^{.. T} 18:38, 8 August 2006 (UTC)

Death of fruits and vegetables

Usually I am able to answer my child's questions alone or by some quick research but this one has me stumped. My son asked me if the blueberries he was eating were dead. Are fruits dead when they are picked? When they rot? Some indeterminate time between these two? I appreciate anyone's help.

James [email removed]

I would personally not consider a fruit or vegetable to be completely dead until it is unable to be planted and grow into a plant. There's still a seed of life inside anything that can be planted and grow. (forgive the pun) And by this reckoning, fruit can live for a very long time. http://en.wikipedia.org/wiki/Seed#Oldest_viable_seed

I believe the cells of most fresh fruits and vegetables are alive. When they die, they rot. The fact that picked fruits can continue to ripen is evidence they are alive. Seeds remain alive even after the fruit that contained it has died. Cooking, canning, toasting, and freezing kill cells, so non-fresh fruits and vegetables are not alive. --Ginkgo100 ^{talk · contribs · e@} 20:56, 7 August 2006 (UTC)

I think when we say that "X is alive", sometimes we mean "X is a living organism". As an example, we never say a person is alive after their heart and brain have permanently stopped working, no matter how many of their cells are still metabolising. So in this sense "alive" and "dead" have no meaning for picked fruit, because a fruit is not an organism. But other times when we say "X is alive" we mean something like "X is a collection of metabolising cells" or "X is a tissue or organ that could still function as part of an organism". So a fruit is alive the way a heart that's about to be transplanted into someone is alive, but not the way a person is alive. The seeds, of course, are alive in both senses. --Allen 21:51, 7 August 2006 (UTC)

There is a difference between plants and animals. In animals, the life of the organism is more important than the individual cells. By analogy, you could view the cells as bees, and the organism as the hive. The life of an individual bee is unimportant, only the hive matters. In plants, however, the individual cells and organs are more important than the organism, since they can survive and reproduce independently. (There are exceptions, like a planarian, which reproduces more like a plant.) So, I don't think you can apply the same rules to determining whether a plant, or portion of a plant, is dead that you apply to a human. I would say a piece of fruit is still alive, as long as it can still grow a new plant. StuRat 10:48, 8 August 2006 (UTC)

I love kids for asking such questions. That love quickly changes to hate when I try to answer them. One of the most important criteria for life is reproduction. Since fruit is itself a reproductive organ (?) it is alive as long as it can reproduce. Or is it the seed that is alive? If you remove it from the fruit, is the fruit then dead? Then again, I can still reproduce if I lose a leg, but that doesn't prove my leg is dead. Aaaarghhh! Also, I am now mixing up the definition of life in general (eg are viruses alive) and specific living things (eg is a headless chicken alive). DirkvdM 10:02, 8 August 2006 (UTC)

How can things live if they are cut off from their source of nutrients? Plucked Fruits have no source, so if they are not dead stright after plucking, they soon will be. THe question of rotting is something else, probbly depending on attack by fungi, bacteria etc. The seeds are not alive either-- only when supplied with nutrients can they grow and live.--Light current 12:01, 8 August 2006 (UTC)

Again, I think you are incorrectly applying animal standards for life and death to plants. The plant world has states between what we know of as life and death in the animal world (with perhaps a few exceptions, like spiders and insects that can stay dormant for years, then "come back to life" when conditions are right). I would say seeds are alive as long as they still possess the ability to sprout. StuRat 22:54, 9 August 2006 (UTC)

I am not eating now. Does that mean I am dead? DirkvdM 08:59, 9 August 2006 (UTC)

LOL. Probably, at least from the neck up! (joking) 8-)--Light current 13:51, 9 August 2006 (UTC)

See life--Light current 13:20, 8 August 2006 (UTC)

Once a fruit is picked, can it be reattached to the plant it was picked from and start growing again? If so then I have to say at the point where this can no longer be done is the point of death. Keep in mind people have severed fingers and had them reattached hours later. Also, it seems link the plant which grows the fruit is what is really 'alive' not the fruit itself.

I saw a headless chicken once (on TV). It would run around the farm yard bumping into things. It was kept 'alive' by its owner pushing corn down its severed neck. 8-(--Light current 14:15, 8 August 2006 (UTC)

Oh my mistake-- it was here Headless_chicken--Light current 14:35, 8 August 2006 (UTC)

Usually not, but after a fruit is picked it can often be planted and grow into a new tree/plant/bush.... TenOfAllTrades(talk) 14:45, 8 August 2006 (UTC)

Yeah but thats because you are providing some nutrition again. THe plucked fruit probaly survives a short time. what about cut flowers in water, are they alive - or just not dehydrated?--Light current 14:58, 8 August 2006 (UTC)

Once I saw a vegetarian eating a banana. I asked her how would she like it if her skin was ripped off and she was eaten alive. Heh. This is by Carl Sagan, regarding your love-hate relationship with children's questions.

In East Africa, in the records of the rocks dating back to about two million years ago, you can find a sequence of worked tools that our ancestors designed and executed. Their lives depending on making and using these tools. This was, or course, Early Stone Age technology. Over time, specially fashioned stones were used for stabbing, chipping, flaking, cutting, carving. Although there are many ways of making stone tools, what is remarkable is that in a given site for enormous periods of time the tools were made in the same way—which means that there must have been educational institutions hundreds of thousands of years ago, even if it was mainly an apprenticeship system. While it's easy to exaggerate the similarities, it's also easy to imagine the equivalent of professors and students in loincloths, laboratory courses, examinations, failing grades, graduation ceremonies, and post graduate education.

When the training is unchanged for immense periods of time, traditions are passed on intact to the next generation. But when what needs to be learned changes quickly, especially in the course of a single generation, it becomes much harder to know what to teach and how to teach it. Then students complain about relevance; respect for their elders diminishes. Teachers despair at how educational standards have deteriorated, and how lackadaisical students have become. In a world in transition, students and teachers bother need to teach themselves one essential skill—learning how to learn.

Except for children (who don't know enough not to ask the important questions), few of us spend much time wondering why Nature is the way it is; where the Cosmos came from, or whether it was always here; if time with one day flow backward, and effects precede causes; or whether there are ultimate limits to what humans can known. There are even children, and I have met some of them, who want to know what a black hole looks like; what is the smallest piece of matter; why we remember the past and not the future; and why there is a Universe.

Every now and then, I'm lucky enough to teach a kindergarten or first-grade class. Many of these children are natural born scientists—although heavy on the wonder side, and light on skepticism. They're curious, intellectually vigorous. Provocative and insightful questions bubble out of them. They exhibit enormous enthusiasm. I'm asked follow-up questions. They've never heard of the notion of "a dumb question."

When I talk to high school seniors however, I find something different. They memorize facts. By and large, though, the joy of discovery, the life behind those facts, has gone out of them. They're worried about asking "dumb questions;" they're willing to accept inadequate answers; they don't pose follow-up questions; the room is awash with sidelong glances to judge, second-by-second, the approval of their peers. They come to class with their questions written out on a pieces of paper, which they surreptitiously examine, waiting their turn, and a oblivious of whatever discussion their peers are at this moment engaged in.

Something has happened between first and twelfth grade, and not just puberty. I'd guess it's partly peer pressure not to excel (except in athletics); partly that the society teaches short-term gratification; partly the impression that science or mathematics won't buy you a sports car; partly that there is so little expected of students; and partly that there are few rewards or role models for intelligent discussion of science and technology—or even for learning for its own sake. Those few who remain interested are vilified as "nerd," "geeks," or "grinds."

I also find many adults are put off when young children pose scientific questions. It is critical that this cannot happen. Why is the Moon round? Why is the grass green? What is a dream? How deep can you dig a hole? When is the world's birthday?" Too often, many teachers and parents answer with irritation or ridicule, or quickly move onto something else: "What did you expect the Moon to be, a square??" Children soon recognize that somehow this question annoys the grown-ups. A few more experiences alike, and the child is lost to science. Why should adults pretend omniscience before 6-year olds, I am baffled. What is wrong with admitting we don't know something? Is our self-esteem that fragile?

— Carl Sagan, The Demon-Haunted World: Science as a Candle in the Dark

— [Mac Davis] (talk)

Agreed. --Proficient 12:17, 10 August 2006 (UTC)

August 8

Cortisone

What causes depletion of cortisone in your body? And what does it mean? --70.40.144.203 00:39, 8 August 2006 (UTC)

Where did you hear this, one of those diet pill commericials? --mboverload@ 00:47, 8 August 2006 (UTC)

That's stress hormone cortisol, suggested to be what makes you fat. — [Mac Davis] (talk)

Cortisone is not used up, per se. Instead, it is usually too low when the adrenal gland has been damaged or destroyed, such as in Addison's disease or Waterhouse-Friderichsen syndrome. Alternatively, it may never form (21 hydroxylase deficiency) or may be turned off by taking steroids such as prednisone. When you have too little cortisol (the name for the chemical in your body), things like low blood pressure and low blood sugar result. Hope this helps! InvictaHOG 00:49, 8 August 2006 (UTC)

Solar Dynamo soon?

Today, In a short fun discussion with a professor we talked a little about various types of sci-fi armagedon movies and laughed at their unsupportive / ridiculous events (if you want to call it that). Eventually, one of my peers mentioned about a possible Solar_dynamo happening in the near future (not sure if they're correct). In addition, they mentioned that it "the electricity will go out". I was wondering if that was just a rumor or it could really happen. If so, how devistating can it be? Thanks in advance for the output!

Did you read the "solar dynamo" article? If you're worried that the "solar dynamo" might happen soon then be very afraid, because it's already happened. It is describing a process that is at work in the sun all the time. Now perhaps what your schoolmates meant was a reversal of the sun's polarity, or whatever, and so um, "causing the electricity to go out." If they mean that it'll cause everything that uses electricity on earth to stop working, well, that's not what the solar dynamo will do. 71.113.119.102 01:32, 8 August 2006 (UTC)

Hmm... the part about the sun's polarity shifting sounds much more correct. I may have just read the wrong thing on the article of the sun. Thanks for the info! Is there any possibility when this might happen? because unless i have been misinformed again (or taken something out of context) they mentioned it happens every 11 years? --Agester 01:50, 8 August 2006 (UTC)

Yes, every 11 years (give or take a few). It is associated with increased solar activity (e.g. solar flares, coronal mass ejections), which can be bad for satellites, but only rarely affects life here on Earth. It is possible for a very active sun to affect power grids and cause short lived outages, but that generally only happens when the grid is already overtaxed, and mostly at high latitudes where the Earth's magnetic shielding is weaker. See: geomagnetic storm. Dragons flight 03:16, 8 August 2006 (UTC)

Could we tap into this energy source? DirkvdM 10:07, 8 August 2006 (UTC)

Is it worth it for a couple of days every eleven years. Philc _T^E_C^I 12:18, 8 August 2006 (UTC)

*blink* you are suggesting solar dynamo only exists a few days every 11 years? If you wanted to tap the energy of it all the time, all you would need is a coil large enough to induct the energy. I will leave coil size up to you (hint, the field exists at the extremities of the sun) --Jmeden2000 15:10, 8 August 2006 (UTC)

Ok but the suns magnetic field is on an 11 year cycle, at the end of which it completely breaks down and starts again. Philc _T^E_C^I 23:08, 8 August 2006 (UTC)

A magnetic field isn't only useful when it changes...

Calculating speed from gravity.

Let's say I drop an object, from the window of the 2nd or 3rd floor, like a ball, and I use a stopwatch to measure the duration of fall. Once the object hits the ground, I stop the stopwatch and now have the time it takes to accelerate via a distance. With the time, using d = .5att (or d = (1/2at^2)), where a = ~32.1 feet/second^2. Plug in time t, and you now have the distance. But is there a way to calculate the speed at which the object hits the ground? (Like in miles/hour). Or am I missing some variables here?

For example, if t = 5.5 seconds, then I would already have reached freefall acceleration of 120 mph. Thanks. NealIRC

There are several ways - a*t gives you the velocity (this assumes no air resistance, as does your calculation). Another way would be to assume conservation of energy - the starting potential energy (m*g*d) = 1/2 * m * v^2. Raul654 01:50, 8 August 2006 (UTC)

For a constant acceleration (as with gravity, as long as you neglect air resistance) your final velocity is equal to your initial velocity (zero, if your object is dropped from rest) plus the acceleration multiplied by elapsed time.

v_final = v_initial + a·t

Acceleration is the rate of change of velocity with time, right? 32 ft·s^-2 tells you that your velocity is changing by 32 feet per second, each second. Every second that goes by, your velocity changes by 32 feet per second, until your smack into the ground. (Dang, I wish you guys would use metric...). TenOfAllTrades(talk) 01:55, 8 August 2006 (UTC)

TenOfAllTrades is correct; but the just to clarify: time is continuous, e.g. you don't speed up all 32 ft/s at the end of each second. You are gradually accruing additional velocity, so you can have fractional seconds. (after 1.5 seconds, you would have v=48 ft/s ). Nimur 19:57, 8 August 2006 (UTC)

My guess

Is it 9.81 m/s^2?--Light current 02:27, 8 August 2006 (UTC)

According to Acceleration due to gravity, it is defined as exactly 9.80665 m/s^2. Raul654 02:46, 8 August 2006 (UTC)

Hey, not bad after 35 yrs not using it! I think I deserve a prize! But I dont think Ill be getting one 8-(--Light current 02:54, 8 August 2006 (UTC)

:-) Here Light, I give you this marble, , as reward for remembering Earth's gravity. Dragons flight 03:08, 8 August 2006 (UTC)

Hey thanks babe! I'll treasure it!--Light current 03:16, 8 August 2006 (UTC) Oh I see -- that brings me back to earth 8-))! --Light current 03:19, 8 August 2006 (UTC)

Accurate value

That is if you are at the vertical geodetic datum; the value decreases as your elevation increases. However, if you need that level of accuracy, you're perhaps better off using G anyways... Titoxd^(?!?) 02:54, 8 August 2006 (UTC)

That value is some kind of average. In St. Petersburg, Florida the actual acceleration of an encyclopedia dropped in a vacuum is closer to 9.79 m/s². --Lambiam^Talk 07:43, 8 August 2006 (UTC)

I agree. The acceleration due to gravity is a naturally occurring phenomenon that can be measured, it's not some abstract concept that is amenable to an arbitrary definition. JackofOz 12:09, 8 August 2006 (UTC)

Sure, it's a defined constant, used as a reference value. The actual number will depend on your location and altitude. It's useful if you need an exact value (this component was stressed under an acceleration of 200 g, the samples were centrifuged at 100,000 g for 2 hours) so that you can make comparisons. It's just like how one atmosphere of pressure is usually pretty close to (but not exactly equal to) the actual atmospheric pressure at a given place and time on Earth. TenOfAllTrades(talk) 12:38, 8 August 2006 (UTC)

Spooky. Shades of those crazy 19th century Americans who tried to legislate for the precise value of π. JackofOz 22:37, 8 August 2006 (UTC)

Pi

Pi is a whole number equal to pi. Its all the other numbers that are wrong. 9-)--Light current 22:55, 8 August 2006 (UTC)

>> Actually Pi does have an precice value it is equal to 4* the intergal from 0 to 1 of dx/(1+x^2). Most people are just not used to this as a numbering system; never the less it is a precice value--Aaron hart 07:52, 9 August 2006 (UTC)

Exactly my point. Trouble is it makes counting and integers etc a bit difficult. I believe it can alos be expressed as the result of many other integrals not to mention infinite series. 9-(--Light current 13:31, 9 August 2006 (UTC)

>>But back to the real question, it does not only apply to the gravitational value of the earth, Acutally it is the two masses one the earth and the other the object accelerating towards it, the small object acctually accelerates the earth towards it, but this is an old theory, acutally gravity is due to the curviture of space-time due to mass, i.e. the moon accutally travels in a staight velocity through space-time that is curved due to the mass of the earth! This is rather complicated and has is due to the fact that matter in space-time is considered as a perfict fluid thats most important characteristic is its energy distribution. Thus the gravitational behavior of any body is determined by its total energy constent, but this is almost imposible to demonstrate by experimentation--Aaron hart 08:01, 9 August 2006 (UTC). I do not believe that it is totally understood!

Pain Threshold

Is there a way, or are there multiple ways, for a person to increase his or her pain threshold significantly?

Do you mean threshold before pain is subjectively experienced, or threshold before you're willing to confess to anything they want to hear? The use of morphine can help, also with the latter. But most analgesics are controlled substances in most countries. There is the gate control theory of pain, which may give some ideas. Also read our article on Pain management. Some people are helped by meditation, others by hypnosis. There are claims that one can train to endure pain, but I've no specific knowledge about the effectiveness. --Lambiam^Talk 07:26, 8 August 2006 (UTC)

I'm reminded of Lawrence of Arabia, who was able to hold his hand over a lighted candle without flinching. When someone said "Doesn't that hurt?", he said "Of course it does, but I don't mind the pain". JackofOz 12:06, 8 August 2006 (UTC)

Great movie - I believe the quote is "Of course it hurts. The trick is not minding that it hurts" --Bmk 14:24, 8 August 2006 (UTC)

Thanks for the correction. My other favourite (hopefully not mis-)quote about pain is Oscar Wilde: "I can stand anything except pain". JackofOz 22:34, 8 August 2006 (UTC)

Did anybody ask the candle "Does't that stink ?" (guess its answer). Any threshold, anyway, is modified by regular use. See sudoku, Mithridate and athletic training.-- DLL ^{.. T} 18:31, 8 August 2006 (UTC)

No, that's not right. Even when it's utterly frustrating, Sudoku is always pure pleasure. JackofOz 22:34, 8 August 2006 (UTC)

The Buddha was known to be great at not caring about pain. But keep in mind, pain is something your body does to you to keep itself alive. You feel pain from a burn so you don't do it again. You feel pain if you get a rock thrown at your head so you don't let it happen again. — [Mac Davis] (talk)

A lot of top class martial artists are known for having colossal pain thresholds. So mine would be discipline, its not about not feeling the pain, but knowing its not the pain thats hurting in you. Philc _T^E_C^I 22:56, 8 August 2006 (UTC)

Well, in that context, the pain is indeed hurting you. But, if you don't want to get kicked in the ribs again, it is best to try to ignore it so you can, as my instructor likes to say, 'move yo' ass out the way of sommin' that's comin' straight atcha! ' That is my take on it. --69.138.61.168 16:46, 9 August 2006 (UTC)

You cannot significantly elevate your pain threshold by non-invasive or nor-pharmacological means. But you can quite effectively increase your pain tolerance by physical, cognitive and affective techniques (in addition to taking the drugs which can temporarily increase the threshold for pain). I assume you were asking about tolerance since all the comment above is about it. I see WP has no article describing any of the two quite opposite ways of describing the experience of pain. Hmm, I don't feel like work right now, but I've put up a pain threshold stub-plus for you. And will look to pain tolerance soon. Which should then at least answer your question. --Seejyb 01:01, 10 August 2006 (UTC)

But one might ask, is increasing your pain threshold good? What are the negative affects to the body? --Proficient 12:20, 10 August 2006 (UTC)

Nanotechnology - Nano Coatings and ultra thin films - Market trends

Hi All,

Please provide me some information or relevant links to facts and figures related to technology trends and market trends in the area of Nano coatings and ultra thin films in relation to Nanotechnology.

Any help regarding this will be gratefully appreciated.

Thanks, --203.99.212.224 06:04, 8 August 2006 (UTC)Aurnav

Have you looked at our article on Nanotechnology? I assure you, it's quite the relevant link. --ByeByeBaby 06:27, 8 August 2006 (UTC)

Yes, I did go thru the article .. however, what I want are facts, figures, graphs , charts etc related to market trends in Nanotech applications ... it should be more business oriented and not just technical information.

and it might be a good idea to check the also relevant homework. Xcomradex 08:22, 8 August 2006 (UTC)

Multiple time dimensions

I have a very hard time understanding the concept of multiple time dimensions.

Since our lone time dimension forms a timeline, i suppose having 2 of them could be described as a "timeplane", where the current time could be described with 2 coordinates.

How does an object move through the timeplane? Is its time trajectory random, or can it be controlled? Or does it move in all directions at the same time, creating an infinite number of timelines in the plane?

How is moving forward in the first time dimension different from moving forward in the second one?

Thanks in advance --Angry russian 11:38, 8 August 2006 (UTC)

The idea of multiple time dimensions is referred to at 2T-Physics. Itzhak Bars is a (if not the) recognised expert on this.

Leaving redlinks to answer questions is pretty unhelpful. Philc _T^E_C^I 13:40, 8 August 2006 (UTC)

Anon might be referring to Second Temporal Dimension, which is not a very helpful stub. (Sorry but I'm not even going to try to get my head round this question. Hopefully someone brighter will be along shortly.)--Shantavira 15:29, 8 August 2006 (UTC)

The idea is inconcievable to us as we are from a universe with a one dimentional timeframe (or timeline in this case) so you won't be able to percieve what the question is referring to if thats what you are trying to do. Since our time line is 1 dimensional, it can only go two ways, and for some reason i don't know, not being a physicist, this side of the speed of light it always goes forwards. Which is fair enough, because being a 1D timeline, if you go from one end to the other, you pass through all the possible timelines, however with a 2D(or more) timeline if you go from one end to the other, either:

1. You miss out a large portion of the possible times,
2. Time periodically jumps back on one of the axis
3. Several times are happening simaltaneously
4. Objects navigate the time plane/space/whatever randomly

Or some other obscure thing I haven't thought of, or we cant understand. Someone with a knowledge of these things please comment. Philc _T^E_C^I 18:39, 8 August 2006 (UTC)

Redlinks can be hellauseful because both "2T-Physics" and "Itzhak Bars" seem very nice google search terms. Dr. Bars' home page suggests another: Two-Time Physics. Sorry, the math is too much for me to write even a stub on it. Sp(2,R) Gauge symmetry acts on phase space, yeah, right, got it, thanks a heap. ;-) Weregerbil 18:30, 8 August 2006 (UTC)

How about if the second temporal dimension is viewed as movement into parallel universes ? For example, if you throw a ball 100 feet in our universe, perhaps you throw it 99 feet in another universe, and 101 in another. As you proceed to parallel universes further in this second temporal direction from ours, you might drop the ball, not even ever have tried to throw it, or you may not exist at all. StuRat 19:54, 8 August 2006 (UTC)

At best, this is highly-theoretical physics mathematics; more realistically, it is pseudo-science. Well, good luck wrapping your head around it; I don't know that it will be productive. Nimur 20:06, 8 August 2006 (UTC)

Actually it is a protoscience, pseudoscience is something else totally.

The parralell universe theory considers all possible universes, not specifically universes with 3 spacial dimensions and 1 time dimension, so inevitably the universe will have been created at some point with more than one time dimension, and as far as I am aware it is impossible for these universes to interact anyway, as there is nothing between them, no spacial or time or any other dimensions, so they are not connected to ours by time or space. 172.206.180.165 20:34, 8 August 2006 (UTC)

Chiropractor titles

A local Chiropractic clinic has opened in my town and the 2 chiropractors there, as stated on the door have BScs and MChiros but before their name the have Dr.

Now, is the title of doctor achieved with the MChiro or have the chiropractors just assumed the title?

Moffo

(added title) Please use the "ask a question" link at the top of the page to ask a new question - then your question will get its own topic heading. In partial answer to your question, you should read the section on "Chiropractic education" in our article on chiropractors --Bmk 16:21, 8 August 2006 (UTC)

May I add that I live in the UK. I apologise about the title thing.

I'm fairly sure that they would have to have doctorates. An MChiro is a masters degree, so they wouldn't have got the title of doctor with it, although they may well have obtained the masters before the doctorate (or after, but that's unlikely). If they aren't really doctors they could get in trouble under the trade descriptions act.

If you live in the UK, you may be interested to know that even the majority of UK medical "doctors" aren't real doctors (in that they do not have a doctorate like an Doctor of Medicine). Most have only Bachelor of Medicine and Surgery degrees. They are officially titled "Registered medical practitioners" in the UK but, whether they have a higher doctorate or not, are afforded the courtasy of using "doctor" as an honorary title. That notwithstanding, it is not illegal to call youself a "Dr" without a higher degree in the UK. You can only get in trouble if you try and use the title in a fraudulant way. Whether chiropractors calling themselves "doctors" without a suitable qualification are committing fraud is open to debate. Rockpocket 19:41, 8 August 2006 (UTC)

Your comment about the majority of UK doctors not being "real" doctors assumes that the title is supposed to indicate possession of a doctorate. According to [8], which quotes the OED, the usage of "doctor" as a term for someone who treats illnesses or diseases goes back to (at least) 1377.--71.246.9.240 03:50, 10 August 2006 (UTC)

My 'assumption' is based on the root of the word. As our article, Doctor (title), tells us:

"Doctor means teacher in Latin. It has been used continuously as an honored academic title for over a millennium in Europe...its primary designation is a person who has obtained a doctorate (that is, a doctoral degree)...From the nineteenth century onward, "doctor" has been popularly used as a synonym for "physician" in Anglophone and many other countries; this term is commonly used as a title of address for physicians, whether or not they hold a doctorate."

Put more simply: doctoral degrees, such as Philosophiæ Doctor and Medicinæ Doctor, include the term "doctor" in their title, while Medicinæ Baccalaureus et Baccalaureus Chirurgiæ - the degree conferred on most British registered medical practitioners - does not. Thus, by "real" i meant "in the original sense of the word", not that British medical doctors are fraudulant or underqualified. Apologies for the confusion. Rockpocket 05:23, 10 August 2006 (UTC)

I was surprised when signing on with a new dentist (in the UK) to see that he described himself on his business card as "Dr" so-and-do, despite only having bachelor's and/or master's degrees in dentistry. --rossb 08:11, 10 August 2006 (UTC)

General practitioners with only bachelor's degrees call themselves "doctor" in Australia too. The funny thing is that many specialists, who have to be trained medical practitioners first, and many of whom really do have Doctorates of Medicine, insist on being called Mr, not Dr. JackofOz 11:18, 10 August 2006 (UTC)

Cost/Price of an EMD SD40-2 Locomotive in 1972

What was the price tag of an EMD SD40-2 diesel-electric locomotive in 1972, the first year they were offered?

I'm going to Google this, only because I am mildly amused by such a question. I wonder if you have already Google'd. But I am now legitimately curious... did you think anyone on the Reference Desk would know this off-hand?!? Or did you just want to solicit us to perform the google-search FOR you? Nimur 20:26, 8 August 2006 (UTC)

These models cost $190 in 2006. Nimur 20:30, 8 August 2006 (UTC)

And I imagine that you were the one who asked the exact same question here. The responses estimate from $100,000 to $500,000. Nimur 20:32, 8 August 2006 (UTC)

And according to the IRS, though they insist this is not official, many EMD SD40s are re-built and can re-designated as SD40-2 models for tax purposes. This would significantly reduce the cost. Nimur 20:38, 8 August 2006 (UTC)

There's nothing wrong with asking - the reference desk isn't really for giving answers to questions - it's for helping people answer their own questions by pointing them in the right direction. In that spirit, i'm going to link to our insanely detailed article on the EMD SD40-2. I was rather surprised that we had an article on this, and even more surprised when it didn't mention the price :( Sorry - I tried --Bmk 20:45, 8 August 2006 (UTC)

Sorry. I didn't mean to sound aggressive, I meant to sound surprised. This is an awfully specific fact; I imagine the only way to find out such a detail is to personally contact a train salesman from 1972. Even then... Nimur 20:49, 8 August 2006 (UTC)

No problem, sorry for the reaction! It is a remarkably obscure fact, as facts on this desk go :) -Bmk 22:03, 8 August 2006 (UTC)

This fact may seem "obscure" and insignificant. However, it serves as a basis for comparing the cost/price in real terms against current locomotive models, and is therefore fairly important. Any info you can add on this would be greatly appreciated. The nearest I've come to the price is approximately $400,000, but an exact figure would carry more weight.

Moths and 100% Nylon

 Will Moths eat 100% Nylon fabric, if it is used as a protective covering for clothing?

Thank you Anna Porter

I dont think they like nylon so its a good protector for clothes. Alternatively, you could use a platic carrier bag. I found that works.--Light current 19:17, 8 August 2006 (UTC)

Indeed, they won't. It is the hatched larvae that munch on your clothing, which they only do after burrowing inside the wool. A moth won't deposit her eggs on a smooth dense fabric. The larvae cannot digest nylon and need animal hair like wool or felt to survive. --Lambiam^Talk 19:25, 8 August 2006 (UTC)

... and that's no myth :--) JackofOz 22:26, 8 August 2006 (UTC)

Dont you mean moth? 8-)--Light current 23:35, 8 August 2006 (UTC)

No, it is a moth, just not a myth. Pay attention please! DirkvdM 09:10, 9 August 2006 (UTC)

Id get that lisp seen to if I were you! 9-)--Light current 13:04, 9 August 2006 (UTC)

Lithp? What lithp? JackofOz 13:30, 9 August 2006 (UTC)

uk Frogs

How long does a small frog grow into its full size (uk)--86.139.143.214 19:41, 8 August 2006 (UTC)

I assume since you asked about time in the UK, that you want it in UK units, like fortnights. :-) StuRat 19:57, 8 August 2006 (UTC)

HEY now, no anti British comments please! 8-)--Light current 22:12, 8 August 2006 (UTC)

Did I get off on the wrong track ? (Or should I say the wrong dual carriage-way ?) :-) StuRat 04:01, 9 August 2006 (UTC)

Well, you seem to have have put your foot metre in it. DirkvdM 09:25, 9 August 2006 (UTC)

What a display of xenophobic ignorance. Philc _T^E_C^I 11:26, 9 August 2006 (UTC)

First I'm being called anti-xenophobic and now xenophobic again. At least I'm wonderfully unpredictable, just the way I like myself. DirkvdM 18:35, 9 August 2006 (UTC)

No, no its all done the best possible taste as Kenny Everett plaing 'Cupid Stunt' used to say.--Light current 14:20, 9 August 2006 (UTC)

Frog life cycles are discussed on the main page. Specifically, "Most temperate species of frogs reproduce between late autumn and early spring. In the UK, most common frog populations produce frogspawn in February, although there is wide variation in timing. Water temperatures at this time of year are relatively low, typically between four and 10 degrees Celsius. Reproducing in these conditions helps the developing tadpoles because dissolved oxygen concentrations in the water are highest at cold temperatures. More importantly, reproducing early in the season ensures that appropriate food is available to the developing frogs at the right time." This suggests between 4 to 6 months from fertilization to frog-form. Nimur 20:01, 8 August 2006 (UTC)

Which is between 8 and 10 fortnights ; but the tadpole life may be quite long before you have a perfect small frog. -- DLL ^{.. T} 20:10, 8 August 2006 (UTC)

8 and ... 12? Nimur

I get 4 to 6 months = 8.5 to 13 fortnights. StuRat 21:40, 8 August 2006 (UTC)

The French don't thrive in the UK. Even when they're small. DirkvdM 09:25, 9 August 2006 (UTC)

No they live in France. Your speech impediment is getting worse! 9-)--Light current 14:10, 9 August 2006 (UTC)

And now I'm being confused with JackofOz. I didn't plan on being that unpredictable. DirkvdM 18:35, 9 August 2006 (UTC)

No I dont think so. Did you not write this lisp:

No, it is a moth, just not a myth. Pay attention please! DirkvdM 09:10, 9 August 2006 (UTC)

--Light current 00:08, 10 August 2006 (UTC)

I officially declare this "irrelevant answer day" on the Science ref desk. I haven't carefully surveyed the other posts, but on this one there are about ten irrelevant comments for every helpful one. :) don't stop, though. It's much more fun to read. --User:bmk.

I'm much, much sexier than Dirk. Not hard to tell us apart. JackofOz 11:09, 10 August 2006 (UTC)

Actual attempt at answer Several years, I think. We used to have lots of frogs in the garden and there seemed to be several sizes of frog reflecting different years. Hundreds of the tiniest frogs, a few at various medium sizes and 2-5 large frogs. Judging by the number of sizes, and making a few (possibly unfounded) assumptions, I'd say a frog takes about 5-8 years to become those really big frogs. Skittle 13:50, 10 August 2006 (UTC)

Incidence of Down's Syndrome decreasing?

The article on Down Syndrome mentions that a kind of 'eugenics by abortion' is happening, where parents undergoing prenatal genetic screening are opting to abort rather than give birth to a Down's child. I've been wondering if this has resulted in a decrease in the incidence of Down's children in the world. In the future, will Down's and other testable genetic disorders be seen only in families that are members of religions that are against abortion? Adambrowne666 23:09, 8 August 2006 (UTC)

Eeep. This is certainly a touchy subject. I'm sure somehow, someone's response will infuriate the internets :/ Anyway. I wonder if your hypothesis is accurate. It does makes sense to me - not just for Down Syndrome, but for numerous other genetic ailments. I wonder if 'eugenics by abortion' is a loaded phrase; but, yes, I tend to agree that this effect would occur, weeding out genetic problems in family-lines who would prefer no child to a diseased child. Another factor is the recessive gene effect (I'm not a biologist so I don't know if this applies to Down Syndrome, but certainly might for other diseases/conditions). It's possible that bad genes are passed through the hereditary line without ever expressing themselves. Perhaps this could continue for many generations; but the rate of occurence would be decreased. I guess a followup question might be whether it is testable. Nimur 23:44, 8 August 2006 (UTC)

Abortion would have an effect on the prevalence, but not the incidence, of Downs Syndrome. There's no "gene" for Downs Syndrome, it results from a chromosomal abnormality, and that abnormality generally arises anew rather than being inherited from someone who already has it. On the other hand, a societal trend to have children early, rather than late, in life, would decrease both incidence and prevalence of Downs Syndrome. - Nunh-huh 23:52, 8 August 2006 (UTC)

While Down's Syndrome is genetic, I don't think it's normally inherited. That is, it's caused by an error in chromosome replication in the sperm and ova of genetically healthy mothers and fathers. However, the tendency toward having errors in chromosome replication may indeed have a genetic component, so this trait could be reduced by abortions.

In a recessive genetic disorder, in unrelated mothers and fathers, the rate of appearance of the disease (phenotype), is proportional to the square of the portion of people with the recessive gene (genotype). That is, if 1 in 10 people carry the gene, then 1 in 100 will have the disease. StuRat 23:55, 8 August 2006 (UTC)

Is it impossible that a tendency to develop chromosomal abnormalities can itself be inherited? -Wfaxon 00:06, 9 August 2006 (UTC)

[ec]

For DS in particular, there's probably not a large "eugenics" effect simply because it's not a simple genetic trait, such as a sickle cell-type recessive mutation, but rather a trisomy of chromosome 21. DS patients rarely have children, so that pathway of genetic perpetuation is limited. It's very possible that parents of DS children have other genetic polymorphisms that may increase the incident of a nondisjunction event, and if these parents produce other viable children those polymorphisms will persist in the population.

The most important risk-factor associated with DS, however, is maternal age at conception. Modern technology has allowed far more 35+-year old women to have children, and far more reporductively-challenged couples to conceive. If I were to hazard a guess, the increased number of children born to older mothers probably offsets the screening effects, but I've not found anything on PubMed just yet that supports my guess or with a clear indication on increased or decreased prevalence of DS. -- Scientizzle 00:07, 9 August 2006 (UTC)

The total prevalence for trisomy 21 is increasing as more older women are having children, in some places as much as 2-fold over the last 20 years. However, there is a divergence between live births and diagnosed cases (At least in European areas with abortion) due to pregnancy termination. One recent study showed that 77% of Parisian fetuses diagnosed with trisomy 21 were aborted. The reference is "Dolk H, Loane M, Garne E, De Walle H, Queisser-Luft A, De Vigan C, Addor MC, Gener B, Haeusler M, Jordan H, Tucker D, Stoll C, Feijoo M, Lillis D, Bianchi F. Trends and geographic inequalities in the prevalence of Down syndrome in Europe, 1980-1999. Rev Epidemiol Sante Publique. 2005 Nov;53 Spec No 2:2S87-95. PMID 16471148" InvictaHOG 00:30, 9 August 2006 (UTC)

Though I don't think this applies at all in the case of DS, one of the stranger side-effects of prenatal abortion is that you have a high chance for a "dysgenic" effect (if we want to use those terms) because heterozygous populations can reproduce more often without getting double-recessive children. In Cyprus, for example, prenatal testing drastically allowed for the decrease in the prevalence of thalassemia (a condition similar to sickle-cell anemia) through pregnancy termination. Prenatal testing though has allowed heterozygous parents to have more children than the would otherwise: children with the double-recessive condition not only drained their family resources, but made them very anxious about having more children; after it was possible to have children without the double-recessive, parents felt more free to have more children. The irony here is that they've basically taken the Mendelian ratios and knocked the double-recessive option out of the picture: now the only options are AA, Aa, and aA. Which means that 2/3 of the children actually born are probably heterozygous, and there are probably more of them due to the larger family size, which a eugenicist of the old school would see as an issue (you are in fact leading to an increased incidence of the trait in the population than you would otherwise, even if the prevalence is decreased). At least, that's my interpretation of it. (I am not a eugenicist, mind you; I don't necessarily think that one needs to lower incidence if working on prevalence will do the job.) --Fastfission 01:11, 9 August 2006 (UTC)

Excellent answers, thank you. Adambrowne666 04:00, 9 August 2006 (UTC)

Down syndrome can be inherited - see Robertsonian translocation. Increases in "spontaneous" nondisjunctions (as noted above, due to older women giving birth) may have a larger effect on the prevalence. But inherited DS cases should be going down due to abortions. zafiroblue05 | Talk 04:25, 9 August 2006 (UTC)

Familial Down syndrom, as our article says, only accounts for 2-3% of all cases of Down Syndrome. There is still no reason to suspect that inherited incidence would go down via abortions (again, since most cases of DS are not caused by people exhibiting DS—the translocation would still presumably be passed along in the non-aborted, non-DS children who are born to such families). Indeed it may even rise, based on similar to logic to what I posted above. It is one of the grim ironies of "eugenics" that attempts which focus on prevalence may lead to solutions of increased incidence. --Fastfission 16:18, 9 August 2006 (UTC)

I find it curious that the questioner apparently assumes that anyone who discovered their in utero child had Down Syndrome would automatically want to end the pregnancy, unless a religious conviction precluded that. I could foresee many pro-choice people choosing to carry such pregnancies to term, perhaps based on experience with Down children, or an attachment formed with the child before its birth. --Ginkgo100 ^{talk · contribs · e@} 18:18, 9 August 2006 (UTC)

I didn't assume that at all. I was referring to the phrase 'eugenics by abortion' in the Down's article, and suggesting it as a tendency that might reveal itself over several generations. Adambrowne666 21:28, 9 August 2006 (UTC)

And the numbers are very high, even though DS is not the worst thing that someone can be born with (relatively long life-expectancy, reputation for kindness and gentleness, able to live independently after some training, etc.), and most people would not consider it to fall under "life not worth living". One of the reasons is likely that it is one of the better known genetic syndromes and so easily identifiable (visually) with mental retardation than many other genetic diseases. --Fastfission 01:05, 11 August 2006 (UTC)

Secondary question: I've read in a few places (articles in newspapers) that the rate of miscarriage due to amnicentitis (sp) plus the number of children incorrectly identified as having Down's Syndrome was greater than the number correctly identified. Is this true? I can't find the right sort of sites to tell me. If it is true, might not to tendency to check for/abort Down's Syndrome be selected out faster than any genetic tendency for the syndrome itself? Skittle 13:46, 10 August 2006 (UTC)

I don't understand the last part of it — are you assuming that the tendency to get prenatal testing done is somehow genetic? I find that pretty unlikely, even with a very flexible notion of inherited psychology; almost all of the key aspects are blatantly cultural and institutional. In any case, prenatal testing and abortion does not necessarily decrease the number of children a family might have; as I mentioned earlier, in many cases it increases the number by allowing parents with at-risk genetics to feel comfortable in increasing their family size without taking on the burden of raising a child with genetic illness. The miscarriage rate for amniocentesis is about 1 in 100. The chance of having a fetus with Down's syndrome in a woman 35 and older is about 1 in 385. I don't know the numbers for "correctly" and "incorrectly" (I'd want to look at numbers like that very carefully because it would be very easy to get strange methodologies on that). However amniocentesis is used to screen more than just DS, so looking at just the DS numbers wouldn't necessarily tell you much. --Fastfission 01:05, 11 August 2006 (UTC)

August 9

Lithium ion batteries

Why do they have 3 terminals? one positive, one negative.. and the third? pogetive? 00:49, 9 August 2006 (UTC)

I would think the third ground. — [Mac Davis] (talk)

Could be for charging. Not sure--Light current 02:55, 9 August 2006 (UTC)

>> I believe it is because the battery contains more than one cell, not sure but probably two. This has advantages for longer life; such as using two 6 volt batteries instead of two 12V for an R.V. but Im not sure as to why. Also lithium ion batteries last between 300-500 charge and discharges, They store best at 40% charge in a refrigerator. They should not be completly discharged, even a full charge is harder on them, Try to cycle 80% percent charge and run down to 20%, charge back to full or 80%. The worst possible senerio is as in laptops or portable DVD players is to keep them pluged in to an outlet, this keeps the battery fully charged at a high temp. You will get longer life out of them if you take out the battery, while using an A.C. Plug.--Aaron hart 09:24, 9 August 2006 (UTC)

My li-ion batteries only have two. Philc _T^E_C^I 11:24, 9 August 2006 (UTC)

I would take them back to the store for a refund!--Light current 11:46, 9 August 2006 (UTC)

No, theyr'e meant to, they are made to be the same size and shape as a pair of AAs, and fit into the same terminals. So there is not terminal for any more pins. Philc _T^E_C^I 11:57, 9 August 2006 (UTC)

So it would seem User:Adam_the_atom is mistaken about there being 3 terminals?--Light current 13:01, 9 August 2006 (UTC)

Is that mentioned in Genesis? I didn't know they had terminals in Adam's day.  :--) JackofOz 13:28, 9 August 2006 (UTC)

Lithium ion cells require precise monitoring during charging to prevent them from over heating and being damages or catching fire. The third terminal is often for a battery charge monitoring (a.k.a. gas gauge) IC inside the pack. This PDF (bq27000.pdf) is the datasheet for one of the ICs manufactured by Texas Instruments if you look at the sample circuit on the second page you'll see they make connections for PACK+, PACK-, and HDQ. HDQ is the communications port in this case.
On other packs (NiMH/NiCd, for example), the third pin might be used to measure the voltage of a single cell for controlling the charge cycle and checking for an overdischarged/damaged pack condition. It could also, theoretically, be connected to a thermistor to measure the pack temperature, which is another method to control the charge cycle in non-lithium chemistries. —Bradley 15:04, 9 August 2006 (UTC)

Excellent response. Isopropyl 18:43, 9 August 2006 (UTC)

Makes sense, did I mention my 2 termianl ones were non-rechargeable (hehe, turned out to be quite improtant) ;-) Philc _T^E_C^I 21:52, 9 August 2006 (UTC)

My cell phone's battery has four terminals; one for ground, one for the the positive voltage, one for a thermocouple (inside the pack), and one for a one-wire bus. I guess the bus goes to some sort of serial EEPROM inside the pack. A lot of other cellphone batteries I've seen have also 4 terminals; I'm guessing their usage is similar to mine. --cesarb 21:27, 10 August 2006 (UTC)

Sexual power

how can i measure my sexual power(without having sex)?.

Interesting question. What is sexual power, and how would you measure it if you were having sex? --Allen 03:56, 9 August 2006 (UTC)

i'm guessing a large magnet, a coil of wire... Xcomradex 08:24, 9 August 2006 (UTC)

>> possibly by the heat produced??--Aaron hart 08:47, 9 August 2006 (UTC)

Hey i m serious...i m gettin married in few weeks..n i dont know i m capable enough ..i want to measure...isn,t there any method to measure?

There isn't an objective measure. There's a lot of fake stuff, and people like to pretend they are better than they are. It isn't a competitive sport. My tip: if you love one another, and are honest with each other about what you know, and what you like, you'll work it out and have fun. And practice makes perfect: you have the rest of your lives to practice. Notinasnaid 08:55, 9 August 2006 (UTC)

>> SORRY,, but on the serious side, you need to comunicate and both of you will learn; it will just get better and better, don't worry about the first time, relax it will help, as stated earlier you have the rest of your lives to practace--Aaron hart 09:29, 9 August 2006 (UTC) thanks it means to became relax is the main point to increase your power....is there any excercise like swimming or jogging that help me strenthen my power...i want to make my...rock solid...so is there any excercise????

Doctors say dont smoke, dont drink (too much), eat well & healthily, take some excercise, get plenty of rest, dont worry etc. If you do all that already and still cant get it up, I would pop along to the doctor for a quick check up!--Light current 11:14, 9 August 2006 (UTC)

I don't know what you mean by "sexual power". It isn't like how good in bed you are is a direct factor of how strong you are, and there is no simple exercise that will increase that (though sex is an athletic activity—when done right!—so being in shape can help things). Your primary goal should be enjoying it, and making sure your partner enjoys it. This has more to do with talking to them about what they enjoy, and trying new things, than any sort of "sexual power". Take it slow, try to have fun with it, and always remember to think of your partner, and you won't be able to go too wrong. If you are having trouble with erectile dysfunction, that is unrelated to your "power"—a doctor would be the best person to consult about that, they see cases about that all the time, it is not a big deal. --Fastfission 11:42, 9 August 2006 (UTC)

As a woman, I can say the aphorism is true: it's not size (or "power") that matters, it's how you use it. Your new wife will be happy for you to learn how to use it together. I doubt she cares about your "power," whatever you mean by that. --Ginkgo100 ^{talk · contribs · e@} 18:20, 9 August 2006 (UTC)

Or : it aint what you got, its the way that you use it! Or alternatively: It dont mean a thing if it aint got that swing?? --Light current

The Wikipedia article on Sexology seems rather flacid. Maybe it should be a Science collaboration of the month. --JWSchmidt 01:14, 10 August 2006 (UTC)

If your concern is the satisfaction of your future partner, then being relaxed about it is more important than anything else. The "first time" is rarely very good, because you have to learn to understand each other's desires and to read each other's signals. Create a relaxed and romantic atmosphere, take your time, and be generous with both compliments and caressing and other forms of affectionate touching. --Lambiam^Talk 01:36, 10 August 2006 (UTC)

>>My only other sugestion is don't drink to much alcohol, high blood pressure pills will effect sexual function, and expecially anti-depresents to a much higher degree than reported, other than that you might want to talk to a doctor and try viagra oc ciallias, it even helps people with no problem at all, and just may be the confidence boster you need.

It will be hard to measure. o_o --Proficient 12:22, 10 August 2006 (UTC)

No you mean: It has to be hard to measure!--Light current 14:59, 10 August 2006 (UTC)

lol --mboverload@ 23:57, 10 August 2006 (UTC)

No you cant get one if Ur laughing!--Light current 14:00, 11 August 2006 (UTC)

Disaster forecasting

How are hurricanes and tornadoes forecasted now? Can they be predicted by measuring wind speeds near the coasts?

You can see them forming on the weather satellite pics.--Light current 12:59, 9 August 2006 (UTC)

Hurricanes can be generally tracked for days in advance. Problem is that people always cut the track too close and don't account for standard errors (ie. it suddenly takes a turn). With tornadoes, one can only track a severe thunderstorm that *could* produce a tornado. Most of the time, people do not take these warnings seriously (since they happen a lot). --Zeizmic 13:11, 9 August 2006 (UTC)

A large percentage of current day weather forecasting (including hurricanes and severe thunderstorms that can produce tornadoes) relies on numerical weather prediction, which involves using complex computer models to simulate the atmosphere and try to predict how systems will progress. Obviously observations such as the wind speeds you mention are also important, especially the upper air measurements we get from radiosondes and the overall views that weather satellites provide that Light current mentions. So, summarizing, observations and rules of thumb from experience are still important in modern day forecasting, but the way we can simulate the atmosphere using today's supercomputers are very important in forecasts. EWS23 (Leave me a message!) 20:16, 9 August 2006 (UTC)

camera

What are the functions of diaphragm and aperture in a camera?

There is more to 'focusing' than just focus. Check the main Camera article to start. For more details, F-stop, aperture, exposure (photography) and focal length will help; and if you want some more theory, optics or refraction may also be useful. In short, they control how much light can enter the camera- this means a different image is formed. Nimur 13:46, 9 August 2006 (UTC)

Also, Diaphragm (optics), since you specifically asked about this. Nimur 13:48, 9 August 2006 (UTC)

The diaphragm is to help it breathe. — [Mac Davis] (talk)

It also keeps it from getting pregnant. --Fastfission 16:19, 9 August 2006 (UTC)

Oh dear, oh dear. Can we keep it serious please! 8-)--Light current 17:06, 9 August 2006 (UTC)

Yes, F, stop. (F being Fastfission) :-) StuRat 18:15, 9 August 2006 (UTC)

Nice one. :) Serious follows. DirkvdM 18:52, 9 August 2006 (UTC)

The Dog Star — ['Mac Davis] (talk)

Oh JC! Cant you all focus on the question--Light current 00:41, 10 August 2006 (UTC)

In an attempt to give an actual answer, the diaphragm regulates the aperture (the hole through which the light enters the camera). There is a constant trade-off between the amount of light and the sharpness of the image. The bigger the hole, the more light will fall into the camera, meaning that you can use a shorter exposure time, resulting in less movement blur (movement of either the subject or the photographer's hand). But a bigger hole also means that any point on the subject will be projected on several points on the sensor or film (forming a little circle), also causing an unsharp image. Perfect sharpness would be achieved with an infinitely small hole, but then the exposure would have to last infinitely long, and most people can't stand still that long. DirkvdM 18:47, 9 August 2006 (UTC)

As the aperture becomes very small, diffusion decreases sharpness. A pinhole camera mav an aperture as small as, literally, a pinhole, but putting a pinhole sized aperture in a good camera would greatly lower the sharpness. There is not a "constant tradeoff" with smaller aperture producing greater sharpness. See lens test data for various lenses. It is very definitely untrue the "Perfect sharpness would be achieved with an infinitely small hole.." One such site, http://www.hevanet.com/cperez/results.html says "Theoretic Diffraction Limits Theoretic diffraction limits at f/22 for green light is 68 lines/mm. By comparison a lenses f/32 diffraction limit is 47 lines/mm. If you look at the test results for all the lenses tested at that f-stop they very nearly ALL perform at that limit. See also a discussion of diffraction, circles of confusion and depth of field in books by Ansel Adams.Edison 19:14, 9 August 2006 (UTC)

Of course, I forgot. The laws of nature have a tendency to break down when the variables get extreme values (extreme with respect to the scale we view the world in, that is, because that's the scale we base our laws on). DirkvdM 13:18, 10 August 2006 (UTC)

I hope that eventually we will have nothing but digital pinhole cameras (which will require highly sensitive photon sensors to allow a quick exposure time). This would allow for pics which are completely in focus, not having to choose between having the foreground or background in focus. I see having to set the exposure time, aperture, focal length, and flash as akin to old cars that required setting the choke, then hand cranking the engine. This is all silly archaic crap we can well do without. StuRat 20:29, 10 August 2006 (UTC)

A large part of artistic photography is about setting those parameters to get the effect you want. You can open the aperture and cut the exposure time to draw attention to a specific object, while blurring out the foreground and background. Or you can stop down the aperture and increase the exposure time to generate motion blur -- or even blur moving objects entirely out of the picture. You can underexpose the scene to generate a dark, moody feel, or overexpose it to bring out detail in shadowed areas. An autoexposing fixed-focus camera like a film point-and-shoot is actually quite limited in what it is useful for. --Serie 21:15, 10 August 2006 (UTC)

Yes, but all those things can be done in post-processing on computer, as well, and give the artist more control. For example, it isn't necessary to only have things at one depth which are sharp, with everything blurry at all other depths. You might very well want one object in the foreground to be sharp along with another in the background. For example, a shot with a football in focus, and the player trying to catch it, at another depth, also in focus, with the other players blurry. This method gives you the freedom to change the pic later (assuming you retain the original), should you want to put the focus on the player scratching his crotch. What could possibly be a higher form of art than that ?  :-) StuRat 21:24, 10 August 2006 (UTC)

I was thinking the same, but that might be even more work than adjusting the camera (so one might build both options into the camera). And motion blur would be impossible because you would need more background than you get on the photo. Also, this is indeed more artistrickery than photography. DirkvdM 06:56, 11 August 2006 (UTC)

You can make a version of motion blur that's virtually indistinguishable from the real thing, using a good photo editor. The "missing background" would only be an issue for extreme levels of motion blur. Typically, you only want enough blur to show that there is motion, not so much that you can't even make out the moving object at all. StuRat 07:07, 11 August 2006 (UTC)

Well, I've never tried this. Have you? Edges are hard to get right in my experience. If you zoom in and edit pixel by pixel you might think that one wrong pixel won't matter, but when you zoom out it stands out like a sore thumb. But then that may only be with sharp edges, so maybe you're right. DirkvdM 20:25, 12 August 2006 (UTC)

I would never try doing this a pixel at a time. I would think you would need to draw a frame around the object to blur, then specify a blur direction, and the pixels in the frame would then be blended with nearby pixels, in that direction only. It should work quite well for solid objects. However, lots of individual hairs could be problematic, much as they are when superimposing one image on another. Perhaps at some point in the future cameras will take pics from two angles, and use that info to identify 3D objects. Then, you would only need to select the 3D object to blur and specify the blur direction. StuRat 20:34, 12 August 2006 (UTC)

I made a pinhole camera and used photo paper as the negative. To avoid the loss of sharpness from printing through the paper backing onto the positive print, I scanned the paper negative and tweaked it with Photoshop to reverse it (both in a mirror image sense and light to dark). The result was pretty good: depth of field from an inch away to infinity, and good sharpness.Edison 03:19, 15 August 2006 (UTC)

Cool. How long was the exposure ? Can you post the pic here ? StuRat 09:15, 15 August 2006 (UTC)

Ships Floating

Hello, Ive searched the Wikipedia database but couldnt find anything. I woudl like to find a detailed article on how/why ships are able to float and not sink in the ocean. A coin will sink but a huge ship made of steel wont, I knwo it has to do with probably bouyancy? but is there a detailed article in Wikipedia explaining this?

Thanks!

Try buoyancy--Light current 14:28, 9 August 2006 (UTC)

Yep - the buoyancy article has the answers. Basically, the trick is that the ship is hollow! It's mostly air. On average, it's less dense than the water, even though its outside is made of metal. If the ship were solid metal, it would sink just like a solid-metal coin. --198.125.178.207 14:47, 9 August 2006 (UTC)

PS: Of course, that's only if the ship is floating in an ocean of water. If it were floating in a sea of mercury, it would stay afloat even if it were solid steel. Because mercury is just that cool. But ignore me - i'm just confusing the matter. --198.125.178.207 14:48, 9 August 2006 (UTC)

If you made a double-hulled ship with a material like Styrofoam between the hulls (to prevent that space from ever flooding), and the volume of Styrofoam was large enough to float the ship, you really could make an unsinkable ship. StuRat 18:11, 9 August 2006 (UTC)

You wouldn't need the hull either, just the styrofoam. There's a guy in Amsterdam who has built his house on a styrofoam platform and the island keeps expanding as he collects more of the stuff.

At the other extreme, there's a houseboat opposite my house that is made of concrete. Any material will work, as long as the average density (including the air inside the boat) is lower than that of water. DirkvdM 18:58, 9 August 2006 (UTC)

If you don't put the Styrofoam inside something fireproof, it can all burn up, and then the ship could sink. StuRat 23:08, 9 August 2006 (UTC)

See also our Concrete ship page. DMacks 19:27, 9 August 2006 (UTC)

If you used styrofoam passengers, they would never drown, either. But they don't pay as well as the human ones. --198.125.178.207 19:35, 9 August 2006 (UTC)

I like Styrofoam people, they always seem so light-hearted. Although, I must admit, many of them are also air-heads. :-) StuRat 23:08, 9 August 2006 (UTC)

Ok since we seem to get this question every while, is it just me, or is it not because the ship weighs less than the water it would displace if submerged and no water could enter the ship. It seems pretty obvious to me, ships float because they are lighter than water (including the air they contain). Am being stupid or are other people? Philc _T^E_C^I 21:56, 9 August 2006 (UTC)

That is correct. An equivalent way of stating that fact is to say that the boat will float if its average density is less than that of water. --Bmk 22:42, 9 August 2006 (UTC)

Simple: If the ship weighs less than the water it displaces it will float.
The ship will "sink down" until the water it displaces equals the weight of the ship. So if you have a really wide ship it can have a pretty low Draft (nautical) (depth the ship goes underwater) --mboverload@ 11:34, 10 August 2006 (UTC)

Thanks for barging in with that response. :-) StuRat 20:31, 10 August 2006 (UTC)

raw bacon

Is raw bacon safe to eat?

Depends on what country the pig came from. — [Mac Davis] (talk)

I Wouldnt try it. I think it, like lots of meats, has bacteria on the surface (if not inside)--Light current 17:08, 9 August 2006 (UTC)

Baste it in something like lime or pineapple juice. Of course, some people say that is "cooking" the meat. --Kainaw ^(talk) 17:23, 9 August 2006 (UTC)

excerpt from meat page

Meat can transmit certain diseases. Undercooked pork sometimes contains the parasites that cause trichinosis or cysticercosis. Chicken is sometimes contaminated with Salmonella enterica disease-causing bacteria. The recent outbreak of bird flu has stimulated global concerns over public health. Cattle tissue occasionally contains the prions that cause variant Creutzfeldt-Jakob Disease.

Is bacon pork or ham? TITQ.--Light current 17:29, 9 August 2006 (UTC)

According to a site I found, trichinosis is very rare in the United States. Cysticercosis is rare, although less so. I wouldn't recomment eating raw bacon, but at least in the United States (and probably other developed countries where the meat is factory-farmed rather than home-farmed), the risks don't appear to be huge. --Ginkgo100 ^{talk · contribs · e@} 18:30, 9 August 2006 (UTC)

Ochg well, tell that to Dr. Finlay--Light current 00:17, 10 August 2006 (UTC)

Yeah, the pork industry in America today is so clean you can eat it raw. That's why I asked what country the pork is from. Anywhere else it is probably dangerous. — [Mac Davis] (talk)

Why would you want to eat the whole pork industry raw? THat would be making a real pig of yourself 8-))--Light current 05:50, 11 August 2006 (UTC)

Ham and bacon are both types of pork. --Ginkgo100 ^{talk · contribs · e@} 18:25, 9 August 2006 (UTC)

Don't forget pastrami! — [Mac Davis] (talk)

Anything can cause diseases. Raw beef can cause Creutzfeldt-Jakob, so shouldn't one eat steak tartare? Raw fish is also a Dutch delicacy. But I have never heard of raw pork, so I suppose there must be a reason for that. DirkvdM 19:03, 9 August 2006 (UTC)

Note that cooked beef can also cause Creutzfeldt-Jakob, AKA bovine spongiform encephalitis, AKA mad cow disease. The protein which causes mad cow isn't alive, so isn't killed by cooking it. Only incineration works. StuRat 23:20, 9 August 2006 (UTC)

So we should all incinerate our meat before eating it? I like my steak well done so that sounds good to me! --Light current 00:01, 10 August 2006 (UTC)

Eating [any] raw meat that isn't pure Grade A or wasn't especially bred to be eaten raw (like in sushi, for example) is like playing Russian Roulette. Eat enough of it, and you are eventually going to get something in your body that you don't want in there. --69.138.61.168 07:20, 10 August 2006 (UTC)

If you're a vegetarian, this will happen a LOT faster than eventually. :--) JackofOz 11:03, 10 August 2006 (UTC)

Possible nitpick: Russian roulette tends to be lethal. Diseases rarely are. DirkvdM 13:23, 10 August 2006 (UTC)

I have ebola, so there...I win!--152.163.100.137 23:47, 10 August 2006 (UTC)

Trichinosis ensues. --Proficient 12:23, 10 August 2006 (UTC)

Tricky noses? DirkvdM 13:23, 10 August 2006 (UTC)

Trichinosis is a pig of a disease to have and can be lethal!--Light current 14:53, 10 August 2006 (UTC)

Is it possible to say that very old religions prohibited certain meats (or fish) and also prohibited eating carrion (leave it to the dogs) just because the rules they wrote down were true, but only before men cooked their food ? Then there would be a hint of that in mosaic law. -- DLL ^{.. T} 17:27, 11 August 2006 (UTC)

It is possible to "say" anything. Whether it is correct is another matter.

It is a universal human trait to attempt to find "meaning" behind everything. We seek to find patterns and relationships. On the one hand this leads to tying facts together to discover scientific laws. On the other, it leads to conspiracy theories. (I am not claiming that all hypotheses of either type are necessarily correct or incorrect, just that the drive to find meaning in the universe is the engine that powers both, ... and other things too.)

Digressing for a moment, in discussing evolutionary adaptations and the development of organs, body chemistry, etc, we often fall into the trap of stating that such-and-such is "for" something or other. This is a capital mistake and a fatal error leading to all sorts of incorrect notions. For example, it seems clear that insect wings are "for" flying. On the other hand some wingless insect never gave birth to a fully-winged child. This leads some folk to wonder what good half a wing would be for flying. Gliding perhaps? Well, the mistake is in assuming that wings were initially developed "for" flying. It actually appears that a wingless insect with a tiny proto-wing would have some small advantage in heat regulation. Over time this advantage would lead to larger proto-wings. Only after the wing had developed would it be put to the use of flying. Notice how the assumption that there was a specific meaning in the development of the wing is what lead to the question of flying with half a wing.

That was quite a digression, all right. Note that even the slightest suggestion of a wing would help to extend the length of a jump, and better wings would make jumping progressively better, until gliding, and then flying, was possible. StuRat 21:18, 17 August 2006 (UTC)

To return to the issue at hand, yes, it may well be that early societies noticed that eating certain things might be detrimental, and so banned the practice. Some biblical laws are so obviously sensible that societies that never heard of the bible developed them themseves (eg: the prohibitions on murder, theft, and perjury). However, in the case here, additional other possibilities exist. One might also consider the notion of communal distinctiveness - they do that, we do this. There is also the notion of inculcating self-discipline over a relatively minor matter as training for having it in regard to more weighty affairs. Or it could have been based on a combination of such reasons. Or no reason at all, merely whim. Any of these is possible. And it is immaterial in this context whether one believes that these regulations were divinely promulgated, thought up by Moses himself, or developed naturally over time. The point is that it is impossible to state for a fact the "purpose" behind such regulations, although, of course, one may speculate. B00P 21:52, 11 August 2006 (UTC)

Flammable

Is vegetable oil or grease flammable?

Yes. Many kitchen fires are caused by oil and grease catching fire on the stove. (Use baking soda & not water to put out the flames!) -- Scientizzle 18:50, 9 August 2006 (UTC)

Or you could put a lid on it (literally, I mean, on the pan - I'm not being rude this time). Water will worsen the fire, ironically. If you mix petrol and water 2:1 (or was that 1:2?) you get a brighter flame than from just petrol. So why isn't water mixed with petrol in combustion engines? DirkvdM 19:08, 9 August 2006 (UTC)

It would rust your block and break your pistons?--Light current 00:24, 10 August 2006 (UTC)

Brighter flame != more energetic. --Jmeden2000 19:14, 9 August 2006 (UTC)

If I remember correctly, brighter flames indicate insufficient oxygen consumption. Clearer flames are hotter. Isopropyl 19:19, 9 August 2006 (UTC)

I'd guess that the water causes the oil to spread out on a surface, thus giving more surface area for combustion, which might result in a brighter flame. There could be other processes at work though --User:bmk

The main reason not to add water to an oil fire is that it causes flaming bits of oil to splatter around the room, which is enough to ruin anyone's day. StuRat 23:14, 9 August 2006 (UTC)

Tested by myself and confirmed. Don't throw water on any petroleum/grease fire. EVER. I am unaware of how well mist works, but I suspect it would never have enough thermal capacity to absorb the heat and stop the reaction. --mboverload@ 11:27, 10 August 2006 (UTC)

A very fine, concentrated mist will work quite well to extinguish nearly any type of fire (a few oddball cases like burning metals excepted), including burning grease or oil. The trick is twofold. A very fine mist is made up of very tiny droplets of water. When these droplets approach a hot fire, they evaporate; this conversion from liquid to gas absorbs a great deal of heat. A side benefit is that this water vapour will not sustain combustion; it displaces oxygen. (Note that generating a sufficiently fine, concentrated mist requires firefighting equipment designed for that purpose; improvised efforts are likely to fail spectacularly.)

Meanwhile, a stream of water – or even large droplets – won't work for the reasons discussed above. The individual droplets are able to stay largely intact when they approach the fire—they just don't boil/evaporate fast enough. You lose both of those beneficial effects (cooling and oxygen displacement.) When they hit the hot oil they heat very rapidly to and above the boiling point. This rapid boiling throws oil everywhere, expanding the fire. Worse, the process breaks the oil up into small droplets with a large surface area that's ideal for encouraging combustion.

See [9], [10] for some discussions of use, or Google water mist fire suppression. TenOfAllTrades(talk) 13:34, 10 August 2006 (UTC)

Oh ok, cool. I wasn't sure if anything less than a stream of water would do it. --mboverload@ 22:12, 10 August 2006 (UTC)

Back to basics : Is vegetable oil or grease flammable? Yes, see Oil lamp. Else, where would you store genies ? -- DLL ^{.. T} 17:22, 11 August 2006 (UTC)

What is dam3?

Hi. I am trying to find a definition of dam3, or dam cubed, in relation to the measurement of volume. The "3" in this case is superscript, indicating cubed. This term is used in the volume measurement of the storage capacity of resevoirs and dams, but it also seems to be used to describe flow. I am trying to find a definition, but Google and Wikipedia don't seem to have anything. I have never heard of this term, but the reports that I am reading use it extensively. Thanks

Cubic decametres. 1 decametre = 10 metres. --Heron 21:27, 9 August 2006 (UTC)

Awright, excellent! I didn't realize it was a standard metric prefix. So 1 dam3 = 1000 cubic meters. My confusion on why it is used in flow measurements is answered by realizing that the reports I am reading add the cubic meters/second up for a month and report the total in dam3 units. So the number of seconds in a month (60X60X24X30) is multiplied by the flow rate, say .970 meters cubed/second and divided by 1000 to give dam3. So, I have to do about 1000 of these calculations for my present report, which is why I am going to go and drink a lot of beer.

Why do that. Why not put the formula into a spreadsheet like Excel and let it do all the calcs? Then you can spend more time drinking! 8-)--Light current 05:13, 11 August 2006 (UTC)

Molten-carbonate fuel cells (MCFCs)

Could one of these cells be used to power a magnetoplasmadynamic thruster capable of carring up to five hundred tons?68.120.69.0 21:06, 9 August 2006 (UTC)

Until now I was not familiar with MCFCs, so I apologize if this is not accurate. Also, I'm not sure what you mean by "carrying" five hundred tons. Do you mean could it "provide five hundred tons of force"?

If so, I'd say the answer is certainly not yet. Plasma rocket design is a very new science, and there are a lot of possibilities, but it seems that the state of the art (according to NASA here) plasma thrusters are operating at about 1 Megawatt and producing 22.5 pounds of thrust. On the "supply" side, this site from the DoE shows a picture of a 1 megawatt MCFC plants, and it looks pretty big. No matter what the scaling law of power vs. thrust is, to scale 22.5 pounds up to 1 million pounds (500 tons) would result in a mammoth MCFC plant. I don't know what applications you have in mind, but I don't see it happening any time soon. But this is all my quick and dirty research, so feel free to correct me (as always). I'm curious though, why do you ask? MCFC seems like an odd power source for space propulsion. --Bmk 21:52, 9 August 2006 (UTC)

Well I was reading the fuel cell page and there was a table showing that this cell could produce 100MW so I thought that may be effeicent enough power for electric thruster of some kind. A link from the MCFCs page showed one at a fair and it wieghs around 20 tons so I was just curious if it produced 100MW and possibly if it did, could it produce enough lift to lift itself and the thruster along with other things.

Ah, I see. Interesting idea. This might work in space - where the power plant is weightless, and you're only working against inertia (I believe plasma thrusters require a vacuum to operate, anyways). However, I still see it as impractical, even in space, because there is probably a large energy requirement to melt the salt electrolyte to get the plant started. --Bmk 22:50, 9 August 2006 (UTC)

Thank you for the help. Its just another crazy idea.

Swallows, Magpies, and Trains, oh my o:

If an eastbound Swallow takes off for Capistrano flying at a velocity of 299792457 m/s and starts to exibit relativistic effects shortly after crossing the Rocky Mountains, while at the same time a westbound train takes off from Cleveland, assuming that the westbound train is accelerating at a constant rate of 24 feet per hour per second, from a start velocity of 24 feet per leapyear. Assuming that the swallow is around 8 ounces and carrying a one pound coconut, and assuming that said swallow has exactly the nessesary drag coefficiant in order to maintain the air-speed velocity at a constant value, and mandating that said swallow does not attempt to deviate in a southerly direction while following the sun, and assuming once again that the train is of sufficient size and velocity that it does observe any quantum effects, and also assuming that it has a nice racing stripe painted on the side, exactly how many flavors of Baskin-Robbins low fat frozen yogurt does the snack car on the train have?--172.163.29.21 22:09, 9 August 2006 (UTC)

I just went through Cleveland on a train last night. I do believe the answer to your question is 0: I saw no frozen yogurt on the snack car. digfarenough (talk) 22:41, 9 August 2006 (UTC)

The question is invalid as it contains spelling errors!--Light current 00:35, 10 August 2006 (UTC)

Two even! Separating them was a drag. DirkvdM 13:46, 10 August 2006 (UTC)

An African or European swallow? User:Zoe|(talk) 01:57, 10 August 2006 (UTC)

I find this train of thought relatively hard to swallow. DirkvdM 13:31, 10 August 2006 (UTC)

That said, the answer is of course none, because according to Google there is no such thing as "Baskin-Robbins low fat frozen yogurt". And we all know Google is the measure of all things. Anyway, even if it did exist, wouldn't it melt as a result of the internal friction caused by the stretching at the speed the train would eventually reach? Assuming it doesn't crash into the ocean before then, which is likely considering the low acceleration. In which case the ocean water would enter the container, melting the yogurt anyway, so there you go. And so do I. On to the next bit of exquisite nonsense. DirkvdM 13:40, 10 August 2006 (UTC)

Relativistic length dilation doesn't cause internal friction - but well done on the triple pun in the previous post. And now I'm hungry for frozen yogurt. --Bmk 17:19, 10 August 2006 (UTC)

People should not post their homework questions here. Thanks 8-)--Light current 17:24, 10 August 2006 (UTC)

August 10

Spectrum of the elements

Hello,

I'm looking for the spectrum of the elements. There used to be a website that had a java program that would present each element's spectrographic signature. You would click on the periodic table and the spectrum of that element would appear. What I would really like is that the spectrographic signature of each element also include all the infrared and ultraviolet lines. Does Wikipedia have this anywhere? I've searched and found nothing. Would Wikipedia like to include such a thing?

Thank you very much, Michael King <email removed to prevent truckloads of spam>

Spectroscopy as a starting point ?--Light current 00:32, 10 August 2006 (UTC)

I can't tell from the question if you're looking for the website that you mentioned. If so, I think I've found it. It's here. And it is really cool! Y'all should check it out. It would be neat if wikipedia included spectra in each element's article. Sounds like a job for...you! Or me if I decide to put the time in. Just make sure you understand the copyright issues, if you do decide to make it a project. --Bmk 00:34, 10 August 2006 (UTC)

Yeah. Have you noticed on that applet that the absorption lines are the same as the emission lines. Or am I misinterpreting it?--Light current 17:46, 10 August 2006 (UTC)

They shouldn't be the same at all. Only the first series of lines (for example, the Lyman Series in hydrogen) should be the same.--G N Frykman 19:59, 10 August 2006 (UTC)

Why shouldn't the be the same (by the same, I really mean they should be negatives of each other). The energy differences are the same whether the electron is absorbing the photon or emitting one. --Bmk 20:24, 10 August 2006 (UTC)

Exactly. But are they really the same?--Light current 23:49, 10 August 2006 (UTC)

ants/anatomy

please could some one tell me where i can go to find a picture of the internal anatomy of an ant i have gone to dozens of sites and can not find one Thank you

Is this [11] no good?--Light current 01:25, 10 August 2006 (UTC)

The picture on this page shows more internal detail. If you click on it, you'll see a larger version. --Lambiam^Talk 02:00, 10 August 2006 (UTC)

Good luck with the operation!--Shantavira 07:29, 10 August 2006 (UTC)

What I want to know is: how the heck can you dissect an ant?--Light current 10:21, 10 August 2006 (UTC)

Very carefully. - Nunh-huh 10:50, 10 August 2006 (UTC)

... and with a minuscule machete. JackofOz 10:59, 10 August 2006 (UTC)

No. The answer is: You lay her on the table and proceed as with any other relative 8-)--Light current 16:45, 10 August 2006 (UTC)

Mmm, here in the Southeastern United States, that could be taken another way. Hyenaste ^(tell) 20:00, 10 August 2006 (UTC)

Wrong again: its called incestual necrophilia--Light current 22:00, 10 August 2006 (UTC)

Taken out of context of course, she isn't necessarily dead. Hyenaste ^(tell) 22:06, 10 August 2006 (UTC)

She soon would be after the first major incision!--Light current 22:13, 10 August 2006 (UTC)

I guess it depends on what kind of dissection-style you are using, or if it is vivisection or not. — [Mac Davis] (talk)

Ahh youve woken up I see Mac!--Light current 05:21, 11 August 2006 (UTC)

o_o --Proficient 13:28, 12 August 2006 (UTC)

ANSI Standard

Posed again at the Computing/IT Reference desk --172.174.40.77 14:33, 10 August 2006 (UTC)

Marshmallow experiment

In the marshmallow experiment described under Deferred gratification, what was done to control for exogenous factors? It seems to me these might include:

• Advanced/delayed development. As I understand it, not all four-year-olds have a clear concept of time, or even enough language, to understand the deal that was being offered. Conceivably, those slower learners who could not understand it might be less likely to wait, even if they had the same deferred gratification, and also less successful in later life.

I can't picture many 4 year olds who couldn't understand this simple proposition. They also were told that they would be notified when the 20 minutes was up, so they didn't need to have any sense of time. StuRat 06:41, 10 August 2006 (UTC)

• Gender, race, etc. Suppose that for as-yet-unknown genetic reasons (I think that in four-year-olds, we can eliminate social conditioning), the group that were able to wait included a greater proportion of white children, more boys, or some other group that statistically earns more money than average. It would follow, then, that they would be more successful in later life, even if deferred gratification did not cause this greater success.

It could also be argued that, if more successful gender and racial groups demonstrated a superior ability to wait for gratification at age 4, then that may be why those groups are more successful. StuRat 06:41, 10 August 2006 (UTC)

• Sugar addiction. From what I've read, widely varying degrees of sugar addiction have been detected in four-year-olds. I have also read that sugar addiction impairs learning and can lead to health problems (e.g. hypoglycemia) later in life. Both these things would negatively impact "success" down the road. I suspect that how long a child could wait would have had at least something to do with the strength of their sugar cravings.

Could be. There was also a child who refused to eat any marshmallows because their mother didn't allow it. StuRat 06:41, 10 August 2006 (UTC)

I also doubt if the sample size was large enough, say 1100 kids, for a 3% margin of error over a 90% confidence interval. StuRat 06:41, 10 August 2006 (UTC)

If these factors were not controlled for, how sure can we be that the results are valid? Perhaps the presence or absence deferred gratification at the age of four has nothing to do with whether it is present in adulthood. NeonMerlin 04:31, 10 August 2006 (UTC)

I don't have access to a research library, but perhaps someone can look this up. The original paper is: Shoda, Y., Mischel, W., Peake, P. K. "Predicting adolescent cognitive and self-regulatory competencies from preschool delay of gratification: Identifying diagnostic conditions". Dev. Psychol. 26(6), 978–86, Nov. 1990.  --Lambiam^Talk 04:54, 10 August 2006 (UTC)

Looks good, I added that ref to the article. StuRat 06:41, 10 August 2006 (UTC)

You can read all the abstracts here. I get the impression that the wikipedia article might overstate the authors conclusions.--Peta 05:02, 10 August 2006 (UTC)

Should not all the above be removed to the relevant talk page?--Light current 17:48, 10 August 2006 (UTC)

I read the article listed, and not much was done to control for those factors. However, that was only the second article done on the subject. It was done 18 years ago, so I am sure more recent articles have done some work towards controlling for confounding variables. However, it isn't safe to rule out social influences in 4 year olds. Children of that age have had plenty of time to learn a wide range of behaviors. And the study referenced another study that was based around toys and present, and showed the same effect. So it is unlikely to be due to sugar addiction. If you search for some more recent articles on the subject and get me the journals, titles, authors, and volumes, I will try and read them and see if anything has been done to answer your questions. Preferably a review on the subject published within the last few years. It's worth noting that those would be very easy variable to control for. --129.110.195.26 14:31, 11 August 2006 (UTC)

Also, that particular journal article only used some parent-submitted measures 10 years later while the children were adolescents. They didn't directly measure success. So the wikipedia article is probably talking about a different experiment. --129.110.195.26 14:58, 11 August 2006 (UTC)

amyotrophic lateral sclerosis

Could someone with als also have peripheral neuropathy? Also, if this person fell because of the neuropathy, could the als worsen faster? thank you jimblab

Peripheral neuropathy could always occur coincidentally in someone with ALS. However, this is not typical and not part of the syndrome. ALS might seem to worsen in times of illness, such as after a fall or with pneumonia. I'm not sure that the disease is actually progressing - more that the neurologic deficits are exaggerated and more pronounced. InvictaHOG 06:59, 10 August 2006 (UTC)

Waterlilies and scum

I get an oily scum on my garden fishponds at certain times of year (for instance now - I live in the UK). I've been told that this is caused by the waterlilies, but I haven't been able to find a good explanation as to why this should be. Any suggestions? --rossb 07:55, 10 August 2006 (UTC)

Pollen? Just a guess. --Bmk 13:20, 10 August 2006 (UTC)

I think it's far more likely to be caused by algae. Googling waterlilies and scum brings up lots of helpful links, such as this one.--Shantavira 14:07, 10 August 2006 (UTC)

I can believe the waterlillies are coated with oil to keep things from eating them and help them to float. Some of this oil might come loose and float on the water. StuRat 20:51, 10 August 2006 (UTC)

8th grade school project on Energy

I need info on the following for my 8th grade school project, energy used/energy wasted/conservation of energy

You should start by reading related articles, such as energy conservation. If you have specific questions about things you don't understand in the articles, feel free to come back and ask them. digfarenough (talk) 14:12, 10 August 2006 (UTC)

Oh, and when I say "start by", I mean, of course, to read the article to get an idea of the subject, then go to a library and look up real books based on references in the articles or important phrases from the articles. Wikipedia should not really be your primary source for, well, anything important. :) digfarenough (talk) 14:14, 10 August 2006 (UTC)

Do NOT reference wikipedia on a school project. Your teacher will not be impressed.

Even though they're basically wrong. — [Mac Davis] (talk)

It's worked for me a few times on college papers when I only had a few hours to write them and no sources. I'm sure you could get away with it in 8th grade. If in doubt, reference the pages or books the wikipedia article references. Of course, if you are serious about the project, it's best to look for good sources. --129.110.195.26 13:43, 11 August 2006 (UTC)

Indeed. Use books. --Proficient 13:29, 12 August 2006 (UTC)

Canon S2 camera behavior

I am starting to get curious about the way my digital camera works, in a way beyond what the readily available articles will illustrate. The process of taking a picture with this particular camera involves sighting it up using the main CCD image sensor, then snapping the whole thing to get an image to save. What I can't figure out is why the shutter in the camera seems to close when the picture is taken, and then snaps open again once it's done. Does it need to close off all light when its reading the image from the CCD? It's most noticeable when the shutter speed is very long, which doesn't support this theory. So can anyone explain why the camera needs this much alone time? --Jmeden2000 14:26, 10 August 2006 (UTC)

What you are describing sounds like the normal behaviour of any SLR camera. When you take the shot, the light from the subject is momentarily diverted away from the viewfinder (usually by a moving prism I believe) and onto the CCD (or film), and the shutter then opens and closes. This means that while the shot is being taken you will not see anything in the viewfinder.--Shantavira 15:36, 10 August 2006 (UTC)

When you're aiming the camera to decide what to take a picture of

• The shutter always open
• The aperture is open all the way
• Every 1/30 of a second or so, the camera reads and resets some of the pixels to display the image on the viewfinder

This leads to a bit of blurring of the viewfinder image, but usually not enough to notice.

When you press the shutter release button

1. The shutter is closed.
2. The entire sensor is reset.
3. The camera sets up the aperture and shutter for the specified exposure.
4. The shutter opens for the specified exposure length.
5. The shutter closes to protect the image while it's being read.
6. The camera reads and resets the sensor.
7. If the exposure was longer than a certain period, 4/3 of a second for Canon cameras, the camera takes a second picture with the shutter closed. This is used to reduce the noise from sensor pixels spontaneously turning themselves on.
8. The shutter opens again and the camera goes into viewfinder mode.

--Serie 21:38, 10 August 2006 (UTC)

Incredible! Thank you for sharing, i wouldn't have thought it needed such a complicated sequence of events to capture what I can already see in the viewfinder. Shantavira: It's not a DSLR camera, there is no separate viewfinder to divert to since both the eyepiece and the flip out screen are driven with the signal from the main CCD.

What is this old "fat removal / body toning" device called?

What is the name for the device being used by the pin-up girl in this illustration? It has a vibrating strap that I think was supposed to jiggle or "melt" the fat away from various areas of the body. --Lph 14:48, 10 August 2006 (UTC)

Wow, google searches with the word vibrating tend to find something completely different... How about belt massager or massage belt; type those into google's image search, seem like pretty popular names for it. Weregerbil 15:13, 10 August 2006 (UTC)

Anyone have the associated caption for the 'postcard'?--Light current 15:37, 10 August 2006 (UTC)

Check out Gil Elvgren and external links therein. Weregerbil 15:44, 10 August 2006 (UTC)

Did they not used to be called just 'slimming machines' ? 8-?--Light current 16:06, 10 August 2006 (UTC)

• There's one exhibited at our gym along with other obsolete exercise machines (the gym is owned, incidentally, by the Smith who invented the Smith machine.) The label on it just says "vibrator". There were a number of brands of them; I think "Gyro-belt" was one of them. Oh my gosh, the things are still being made. --jpgordon^∇∆∇∆ 23:17, 10 August 2006 (UTC)

Thanks everyone! I'm going to put Belt massager into WP:RA. --Lph 04:34, 11 August 2006 (UTC)

Last time I checked, it was already there, but under a different name. I may have removed it when I was working in there because the requester requested something like "those shaking belts that were supposed to lose weight in the 70s," and I couldn't get a name. — [Mac Davis] (talk)

Here's where I put it. --Lph 12:41, 11 August 2006 (UTC)

And if you'd believe it, those things are still popular in Japan. I've yet to find a gym here that didn't have at least one of them installed (usually faithfully used by at least one wrinkly old man).  freshofftheufoΓΛĿЌ  19:41, 11 August 2006 (UTC)

Care of guitar loudspeaker cabs

I have a Trace Elliot cab with 1x15" drive unit. I keep it in the car cos its too heavy to lift on my own. Will the changing environment (ie cold, heat, damp, dry etc) in the car finally cause damage to the cone or the voice coil? I had one large speaker coil fail after it had been standing unused in the house for some years -- never did find out why but I think it was an aluminium voice coil. --Light current 17:42, 10 August 2006 (UTC)

One thing I can think of is that cold equipment brought into a warmer room will get condensation on it, especially the metal parts. If you turn it on then, that might cause some short circuits. If it has been in the car overnight it might be colder and the risk might be greater and it may take longer for it to acclimatise. DirkvdM 07:39, 11 August 2006 (UTC)

I was thinking more of corrosion and/or rot damage.--Light current 13:53, 11 August 2006 (UTC)

Strange lump

Sometimes I spit out a small beige elastic lump, which stinks nearly. I wonder what it is? NoN

Ahem, its Phlegm--Light current 17:25, 10 August 2006 (UTC)

Really? It's a more solid piece, apparently something else. NoN

Yeh sometimes I get one, it strongly resembles the seeds from inside a Bell pepper, so I just assumed it was that. We maybe talking about different things. Hehe Philc _T^E_C^I 19:55, 10 August 2006 (UTC)

I get them, too. They are pieces of food that get stuck in the throat. Later, you cough them up. They are pretty nasty. StuRat 20:45, 10 August 2006 (UTC)

"Tonsillolith". --Femto 21:08, 10 August 2006 (UTC)

My faith in Wikipedia having an article about everything is restored. —Daniel (‽) 10:06, 11 August 2006 (UTC)

Are you sure? Check everything. Oh yes you are right!--Light current 13:55, 11 August 2006 (UTC)

Heh, I for one almost lost my faith. There are redirects for tonsil stone, tonsil stones, tonsillith, tonsilloliths, even throat booger. But I of course (why I remembered it more easily than "tonsil stone" remains a mystery to me), searched first for tonsilith whose redirect didn't exist yet. Slackers. Femto 15:26, 11 August 2006 (UTC)

Gross. --Proficient 13:30, 12 August 2006 (UTC)

Ants !!

I found a some in my car; assuming I vacuum all of the food crumbs and eliminate food sources, how long can I expect them to survive (assuming I don't use bait)?

Did they make a nest in the car? If so, they will try to stay there and venture out for food. A fellow employee got ants in his Jeep and they refused to leave. I continually suggested he bug-bomb the thing. --Kainaw ^(talk) 19:34, 10 August 2006 (UTC)

Put it in a garage so you can bug bomb the inside and outside at once. StuRat 20:41, 10 August 2006 (UTC)x

Just use some Nippon or equivalent ant killer--Light current 21:58, 10 August 2006 (UTC)

Dunno why, I read that as "Napalm" and thought "that might be a bit excessive", but then I realized we don't know just how big/many/strong the ants are. DMacks 06:49, 11 August 2006 (UTC)

Yeah napalm would also be good if you dont mind incinerating the car. 8-)--Light current 06:53, 11 August 2006 (UTC)

Maybe instead of vacuuming the crumbs you should try vacuuming the ants. Or maybe you should create a vacuum around the ants. Anchoress 07:13, 11 August 2006 (UTC)

Move the car a few blocks away from your home. Wait until the ants have gotten out in search for food. Drive the car back to the house. Repeat this until enough ants have been lost to the nest that it can no longer survive. DirkvdM 07:47, 11 August 2006 (UTC)

How resilient are ants to heat? Since its summer (at least in the N hemisphere) things probably get pretty warm during the day. To push it over the tipping point, start the car and set the interior heat to full, and let it sit for half an hour. By that time, the ants should be sufficiently uncomfortable and may consider relocating.

Or you could leave the car in a closed garage when you do that, and kill them with carbon monoxide. Of course, you'd need to let it run out of gas then leave it there until all the CO had dissipated, or you would die, too, but that's just being picky. StuRat 18:00, 11 August 2006 (UTC)

Havent we got a page on insecticides?--Light current 18:11, 11 August 2006 (UTC)

Vacuum the ants. --Proficient 13:31, 12 August 2006 (UTC)

organic chemist

I've been thinking about going to school and doing something with my life and one thing that im interested in is organic chemistry how long would it take before I could have a career and what kind of jobs do they have? also what kind of money and schooling does it entail?

Aren't all chemists organic ? :-) StuRat 20:39, 10 August 2006 (UTC)

I'm no expert, but here's my best shot. Quoting from chemist:

"The three major employers of chemists are academic institutions, industry, especially the chemical industry and the pharmaceutical industry, and government laboratories."

In the US (I don't think it's terribly different elsewhere) you need a BA/BS majoring in chemistry or biochemistry, which usually takes 4 years, followed by at least a masters and most likely a PhD, which would take one to five more years. For academia, figure on a few more years as a postdoc.

The other option is to go into chemical engineering. This takes a BSE. You can get decent jobs with that, and is usually all you need to get licensed, but for better-paying, more prestigious work you would eventually want a MS and probably an engineer's degree.

You might also want to look at pharmacy.--Pyroclastic 20:10, 10 August 2006 (UTC)

there is much more opportunity in chemical engineering than in straight chemistry...go to school for organic chemistry but keep your options open. Many of the classes for chemical engineering overlap with chemistry at the undergrad level.

Nitrocellulose underwear

If you were to make underwear out of nitrocellulose, would you be able to ignite it on demand, or would you be at constant risk of spontaneously blowing your own ass off? --Serie 21:41, 10 August 2006 (UTC)

I just wouldnt walk too fast or make any sudden movements. --Light current 22:04, 10 August 2006 (UTC)

Nitrocellulose doesn't combust on contact at room temperature. It is very flammable, but you'd be ok as long as you don't have a really hot ass. Ahem, speaking scientifically. Now, if you had underwear made out of nitroglycerin... then you'd be in trouble. --Bmk 03:15, 11 August 2006 (UTC)

Yes well, i was thinking of the friction between your legs when you walk fast heating up the nitrocellulose and causing combustion.

A little poem springs to mind:

• The boy stood on the burning deck,
• His pocket full of crackers.
• A spark jumped up his trouser leg
• And....

well you can guess the last line!

Anon

--Light current 03:24, 11 August 2006 (UTC)

I couldn't guess it, I'm not British enough. Its "And paralyzed his knackers" in case anyone is wondering. pschemp | talk 04:00, 11 August 2006 (UTC)

Well you did guess correctly!--Light current 04:05, 11 August 2006 (UTC)

Thanks, I couldn't get it. — [Mac Davis] (talk)

Me either. --69.138.61.168 06:18, 11 August 2006 (UTC)

Perhaps it only known in UK--Light current 06:35, 11 August 2006 (UTC)

Never mind your donkey. I'd be more worried about the front. DirkvdM 07:51, 11 August 2006 (UTC)

Thats where your knackers are if youve got any!--Light current 13:49, 11 August 2006 (UTC)

I can't guess it either, unless the answer is on top of me. --Proficient 13:32, 12 August 2006 (UTC)

Cancer pain

My cousin died from liver cancer recently. At his funeral his minister mentioned how he was in terrible pain in his final days, which got me to thinking, what kind of pain does a cancer patient feel? Are the effects of, say, lung cancer similar to those of breast cancer or skin cancer? What about chemotherapy or radiation treatment, how do they make you feel?

Chemo mainly causes nausea, while radiation therapy can be completely painless. StuRat 23:22, 10 August 2006 (UTC)

My father had/has a form of skin cancer. He reported no pain--Light current 00:00, 11 August 2006 (UTC)

Cancer can be painful depending on its location (or the location of metastases). This page gives a good quick outline. Pain occurs when a tumour grows to the point where it compresses/stretches another body structure that contains nerves. TenOfAllTrades(talk) 01:55, 11 August 2006 (UTC)

Strange lump Mk2

I have a strange lump om my right thumb. Doctor initially said it was a ganglion cyst. But another doctor said it was too near the surface for that. Its about 10mm x 5mm and is sometimes painful but not usually. Any ideas?--Light current 23:55, 10 August 2006 (UTC)

A bone spur ? StuRat 00:05, 11 August 2006 (UTC)

No its too soft!--Light current 00:10, 11 August 2006 (UTC)

How about a simple wart? --Bmk 01:52, 11 August 2006 (UTC)

Uuuuh man i just looked at the link i made - that is one horrible case of warts in the picture! --Bmk 01:53, 11 August 2006 (UTC)

No its not a wart (I have warts too! so I know wart theyre like 8-))- its sort of just under the skin!--Light current 02:54, 11 August 2006 (UTC)

Uh no offense but we are not doctors. I wouldn't trust any medical advice you recieve here, nor ask for any. pschemp | talk 04:01, 11 August 2006 (UTC)

Im not asking for medical advice. Ive seen two doctors for that. im asking people what they think it could possibly be!--Light current 04:04, 11 August 2006 (UTC)

Actually, looking at the page on ganglion cyst I now think thats what it is. (the second doctor was an inexperienced junior). Ill see what the hand surgeon says. --Light current 04:25, 11 August 2006 (UTC)

The other day I was walking around with one of my friends when he noticed something on this rightmost knuckle—it almost suddenly appeared—it looked like the picture of a ganglion cyst. "It's scaring me not because it was there, but because I can feel it moving." It subsided. He associated it with him hitting his hand against a pole about three times in that place. Maybe something in his knuckle broke and a gas bubble formed? — [Mac Davis] (talk)

Sinovial fluid perhaps. You can sort of feel ganglion cysts moving. I had one before. BUT....why did your friend continue to hit his hand agaist the pole after the first time? TITQ --Light current 05:18, 11 August 2006 (UTC)

How to produce TiCL4 in industry

please tell me how to produce TiCl4 from Ilmenite ore in industry. why the producer usually produce TiCl4 from Rutile without Ilmenite. AND could you tell me how to separate Vanadium from crude TiCl4

Is this homework by any chance? Why not try looking at the pages I have linked for you and try to work it out for yourself?--Light current 03:02, 11 August 2006 (UTC)

How do you get Vanadium from TiCl₄? Isopropyl 13:57, 11 August 2006 (UTC)

You dont. Why dont you look at the pages Ive linked! 8-)--Light current 14:03, 11 August 2006 (UTC)

Alchemy. Titoxd^(?!?) 09:44, 12 August 2006 (UTC)

IMAGE TRANSFER CONSTANT.

I Wanna know what is

You wanna??? Try rephrasing the question--Light current 04:42, 11 August 2006 (UTC)

I think they want to know what "image transfer constant" means. I can't help, except to say it apparently has something to do with electronics ([12]). --Allen 04:51, 11 August 2006 (UTC)

Doesnt mean anything in my electronics knowledge!--Light current 05:01, 11 August 2006 (UTC)

Passengers boarding bridges.

tell me more about passengers boarding bridges, technology used in it. and also manufacturers— Preceding unsigned comment added by 59.144.44.56 (talk • contribs)

Tell you what? TRy rephrasing--Light current 05:45, 11 August 2006 (UTC)

Do you mean a jetway? Take a look at the article and its links.--Shantavira 07:13, 11 August 2006 (UTC)

solution of liquids inside vessels

A niece, who is very concerned about health issues, recently told me that she was avoiding buying mineral water in plastic bottles, because "the plastic gets dissolved" and was instead using only glass bottles.

This set me thinking about the whole issue of the solubility of vessels. I remember from my physics lessons in school that all vessels are dissolved to a certain extent by the contained liquid and also, though it may not be strictly relevant, that research in West Africa, where I worked for many years, indicated that when the local people stopped using the traditional iron cauldrons for their stews and went for more modern cooking appliances, they lost out on iron in their diet (derived from the cauldron).

I realize that the issues are extremely complex because they depend on: the nature of the vessel, whether wood, pottery, glass, platic; what the liquid is...anything from water, whiskey, sulphuric acid; maybe the environmental conditions such as temperature.

Even with water the nature of acidity and impurities in the water would presumably have an effect.

So to keep in simple, I am requesting as to whether anybody has statistical data on the solubility of different types of vessels in water (perhaps of different qualities) contained in the vessels. Are these rates to be considered signficant in any case in terms of ingestion by the drinker or are they, as one scientist told me over the phone last night, just of laboratory interest like the phenomenon that the glass in your window pane is gradually sliding downwards.85.12.64.148 08:50, 11 August 2006 (UTC)F.D. O'Reilly −Ihana enterprises

I might not be a full fledged scientist but I'd think that the plastic in most bottles will not dissolve, in any substantial amount, into the liquid it contains. Even if it did dissolve into the liquid it contained, you should remember that little children swallow plastic bits from their toys all the time, it simply passes through their system. PvT 09:27, 11 August 2006 (UTC)

Who cares if plastic got into the water? Why does she care? Before you do anything, she has to tell you why it matters =D. Oh yeah, and glass doesn't flow =D. People just got that idea because the way they used to make windows would make the edges "bulge". So people see old windows, see that the bottom seems to be "thicker" and assume water is liquid. Cheers --mboverload@ 09:45, 11 August 2006 (UTC)

I ve learned something today: solid glass doesnt flow. But rock and mountains do (v slowly)--Light current 14:15, 11 August 2006 (UTC)

Yeh the sliding glass phenonemon is a myth that derives from the fact that early panes of glass are thicker at one end, because the technology wasn't accurate enough to produce flat glass, not because they changed shape. I would consider the effects of using iron pots, irrelavent to this case, as plastic and iron are extremely different physically and chemically. The only thing I have heard about plastic bottles is that the free radicals on the end of the polymerised chains cause carbondioxide to be absorded out of the water, and connect to then ends of the chains, but all that does is decrease fizziness. Anyway plastic is made of carbon and hydrogen neither of which are harmful (infact they are essential for survival) so I dont see any problems with ingesting microscopic amounts anyway. Philc _T^E_C^I 12:00, 11 August 2006 (UTC)

It's quite absurd to say that everything made out of carbon and hydrogen is completely safe. Thousands of hydrocarbons are toxic, including some in plastic containers. StuRat 00:49, 12 August 2006 (UTC)

There should be little concern that plastic will dissolve in water, or anything else you want to drink. But there is legitimate concern about plasticizers such as phthalates, which are non-polymeric chemical compounds added to the plastics to improve their physical properties. There are controversies surrounding the health effects of these compounds. --Ed (Edgar181) 12:49, 11 August 2006 (UTC)

It sounds to me as if your niece has succumbed to the plastic-dioxin hoax. --Ginkgo100 ^{talk · contribs · e@} 17:37, 11 August 2006 (UTC)

Plastics most definitely do give off chemicals into the liquid they contain. This seems to be particularly true if the liquid is acidic. Ever notice a total lack of plastic pickle jars ? There is a reason for this. Spaghetti sauce also usually comes in glass, as plastic bottles, especially soft ones, tend to absorb tomato color and odor, just as the sauce absorbs a plastic taste and odor. Soft plastics, like those used in two liter pop bottles, also seem worse than hard plastics. Time is another important factor. If you wait long enough, anything in a plastic bottle will acquire an unpleasant plastic taste. This is why water in plastic bottles has an expiration date. Temperature is also important. Keeping plastics cool would lower the speed at which the diffusion of chemicals into the contents takes place. However, avoid freezing, as the stress put on the bottle by the contents expanding actually increases diffusion of chemicals from the plastic. To be completely safe, avoid plastic wherever possible. Now, if anyone doubts what I've said here, get a plastic pop bottle, pop in a metal can, and pop in a glass bottle; store each under identical conditions for 10 years, then compare the three. The plastic bottle version will be completely flat and disgusting, while the pop in the can will be better (perhaps with a metallic taste) and the pop in the glass bottle will be exactly the same as when new.

You say that you have to avoid plastics to be safe, but you fail to give any reason to actually do so. --mboverload@ 00:49, 12 August 2006 (UTC)

yes there is a reason for no plastic pickle jars, and it has nothing to do with leaching of plastic components. a lot of plastics are actually rather permeable to oxygen, much more so than glass, so putting pickles in plastic would result in them not keeping as well. and the acidic point you have confused with items in metal jars, such as aluminium. here liquid acidity plays a role, becuase it reacts with the metal surface, contaminating the food with metal ions. Xcomradex 02:13, 12 August 2006 (UTC)

See, this is why I avoid this kind of "omg it's bad more me" thinking. It always turns out to be misinformation crud. --mboverload@ 09:37, 12 August 2006 (UTC)

A lot of people's opinions/facts here seem to contradict each other. Does anyone have a viable source for this information? --Proficient 13:39, 12 August 2006 (UTC)

Potency of liquid explosives

With the recently foiled plot to blow up passenger airplaines by mixing liquid explosives, a danish expert on television explained that as little as 100ml explosives would be enough to blow up a plane. That's some pretty intense firepower, if you ask me. The article on organic peroxide isn't very helpful in determining how explosive it is, but I would assume the exact details on where on the plane the explosion is placed is important. Merely blowing a small hole in the fuselage clearly isn't enough.

Is the terrorists plan even feasible? Could a skilled pilot land a damaged plane on the sea, if the plane is only partially destroyed?

Merely blowing a small hole in the fuselage clearly isn't enough. Pardon 8-? Have you ever made a small hole in a balloon? What happens?--Light current 13:39, 11 August 2006 (UTC)

I was under the impression that the bulk of air travel is not by balloon these days? Blowing a small hole in a plane's hull will have extremely uncomfortable effects and will probably cause a few deaths, but it would not necessarily induce the plane to crash. dab (ᛏ) 13:51, 11 August 2006 (UTC)

I too must have miised it when they unpacked and inflated the planes at heathrow. Philc _T^E_C^I 20:25, 11 August 2006 (UTC)

What you mean you can breathe ok at 30000 ft?--Light current 14:06, 11 August 2006 (UTC)

no, why? dab (ᛏ) 14:18, 11 August 2006 (UTC)

Lack of oxygen after being sucked thro a window! (or decompression) See altitude sickness--Light current 17:29, 11 August 2006 (UTC)

I would have to side with the pessimists. A small hole in an otherwise smooth airframe travelling 450MPH at 30000' is nothing short of catastrophic. If you're lucky, the plane might make it down in one piece. If you're even more lucky, it will do so on a runway or other suitable facility. The article on Oplan Bojinka has more details relevant to the question at hand, which is how much damage could a little explosive do to an airliner. The 'successful' 1994 Manila Air bombing had 1/10th the intended quantity (for 'testing purposes') and was enough to kill one, injure 11, and force the plane to perform an emergency landing. --66.195.232.121 14:19, 11 August 2006 (UTC)

The effects of explosive decompression vary; see for example Turkish Airlines Flight 981 and Aloha Airlines Flight 243. --Lambiam^Talk 14:59, 11 August 2006 (UTC)

I would actually interpret the Philippine Airlines Flight 434 bombing differently: a bomb big enough to split a man in half makes a hole in the plane, and the plane lands succesfully. Death and injuries were caused by the explosion, not by the hole. The real damage to the plane comes from any avionics that are affected (hydraulic and electrical wires traveling throughout the plane). Bomb: death, fire: death, damage to avionics: death, air leakage: discomfort. The only place where decompression instantly kills you is Hollywood movies. Reading material: Cabin pressurization, [13][14][15] (from the first page of google results for plane hole myth). Weregerbil 15:04, 11 August 2006 (UTC)

The plane showed surprising resiliency, but it was only subject to 1/10th the nominal explosive volume. Decompression is one thing, a huge hole in a fuselage is quite another.

I commonly see the argument that a pinhole in a plane will take it down. My father has worked all his adult life as an aircraft mechanic. His job is repairing holes on the body of passenger jets. Every flight puts holes all over the plane. Lightning turns it into, as my father describes, swiss cheese. So, am I to believe that my father has not been working his whole adult life and not only made up the story of fixing holes in the plane's body but also faked the repair shop I visited him at and all those body sheets with little holes in them that he was filling in? --Kainaw ^(talk) 17:45, 11 August 2006 (UTC)

A pinhole wont take it down, but what about a 2" dia hole? See explosive decompression Also there is a way to stop a balloon exploding when puctured with a pin. Put a piece of sticky tape on the surface first then ouncture thro that. Does this tell you anything about the problem? It should!--Light current 17:51, 11 August 2006 (UTC)

....And dont say all planes should be wrapped in sticky tape!--Light current 18:02, 11 August 2006 (UTC)

A small hole would cause the cabin to decompress slowly. Note that the air is nowhere near a vacuum at the altitude planes fly, however. The problem becomes breathing in the thin air. The oxygen masks would drop, and that would allow the passengers to breath. The pilot would also likely decide to lose altitude to a point where people could breath without the oxygen masks. Also note that it takes some 10 minutes to die from total oxygen deprivation, while we are only talking about a slight reduction in the oxygen level (due to the thin air), so it might take hours for people to die, even if they had no oxygen masks and stayed at high altitude. Finally, an emergency landing would be made at the first available airport (not "in the sea", which would be deadly). The only likely deaths would be as a result of the explosion and from heart attacks, due to the stress. StuRat 18:21, 11 August 2006 (UTC)

Assuming you had oxygen to breathe, its a question of whether the low pressure or the rate of decompression, or the extremely low temperatures would kill you. Im not certian after looking at a number of our pages on related subjcts. I suppose it depends on how fit you are, and how long you are exposed to this environment. 8-(--Light current 18:36, 11 August 2006 (UTC)

A small hole wouldn't cause much of a temp drop, except right around it. I should think the heating system on board could easily keep pace with the heat loss through the hole, especially once the it was plugged (this might even happen automatically, if a blanket or pillow gets sucked up against it). Another effect would be noise. It might be quite loud near the hole, causing hearing damage to those nearby. StuRat 23:58, 11 August 2006 (UTC)

Loss of cabin pressure isn't a deadly incident, surely. But you all seem to think that a large nitroglycerin bomb going off inside an airplane would be a casual occurrence! A huge bomb blowing a gaping hole in the side of an aircraft at altitude is certainly cause for concern in my book.

Loss of cabin pressure at altitude (e.g. 35000ft) is certainly deadly. See Helios Airways Flight 522 and Payne Stewart for examples where death was most likely by hypoxia; alternatively if decompression occurs suddenly (e.g. as the result of an explosion or structural failure) the fuselage can be ripped open as happened on Turkish Airlines Flight 981. IIRC, at 35000ft hypoxia can incapacitate the pilot within 15-20 seconds without emergency oxygen following a rapid decompression. In this event the pilots rapidly don their oxygen masks and execute an emergency descent; their vision is likely to be impaired as the pressure drop causes tears to evaporate from the surface of the eye, and they may have suffered severe hearing damage or perforation of their eardrums. Meanwhile any passengers who have failed to get their oxygen masks on can expect to be suffering permanent effects within two minutes, as lowered pressure causes blood oxygen to diffuse back into the lungs. The outside temperature is roughly -56ºC so it is likely to get rather cold rather quickly, even with the heat turned up (although this would obviously depend on the size of the hole). As a result of the emergency descent (to below 18000ft to ensure the safety of passengers), fuel consumption will be drastically increased and range will be correspondingly shortened - if this occurred far from an airport there is a real likelihood of a crash or ditching attempt. --Yummifruitbat 03:11, 12 August 2006 (UTC)

Strength of HCL

There is an experiment for calculating the strength of HCL. It is a titration using NaOH. After the titration I used a formula with the figure 3.646. I multiplied this figure to the mL of NaOH. Where does this figure come from.

• Roughly speaking, because HCl and NaOH are a strong acid and base respectively (and of roughly equal strength in each direction), it takes 1 mol of HCl to neutralise 1 mol of NaOH, with a result that is pH neutral - 7. So if you have 10 mL of 1 M NaOH, then that's 0.01 mol of NaOH, which has to react with 0.01 mol of HCl. If that takes 5 mL of HCl, then you have 0.01 mol / 5 mL = 2 M, for example. Your calculation probably has that kind of reasoning hidden in it somewhere. Confusing Manifestation 15:05, 11 August 2006 (UTC)

Damn edit conflicts!! :)

So, the titration probably told you that $V_{NaOH}$ mL NaOH of a given molarity $M_{NaOH}$ neutralized $V_{HCl}$ mL HCl of unknown molarity $M_{HCl}$.

$M_{NaOH}$ has units of moles/L, and you want a value in moles, so you probably multiplied the number of mL of NaOH by ${\frac {M_{NaOH}}{1000}}$ (since you measured the NaOH in mL not L).

So, $N_{NaOH}=V_{NaOH}{\frac {M_{NaOH}}{1000}}$. $N_{NaOH}$ is the number of moles of NaOH used. Since NaOH and HCl both separate into only two ions, you can simply take $M_{HCl}=1000{\frac {N_{NaOH}}{V_{HCl}}}$ to get the molarity of HCl. I'm not sure which one of these numbers was 3.646, but it probably depended on what molarity of NaOH you were using to do the titration. --Bmk 15:09, 11 August 2006 (UTC)

The molar mass of HCl is given as 36.46 g/mol. Was there a factor of 0.1 mol/l for the NaOH? --Lambiam^Talk 15:24, 11 August 2006 (UTC)

Please don't confuse the strength of an acid with its concentration. I suspect the original question was to calculate the mass concentration of the HCl, with units in g/l. HCl is a strong acid at all times, but it can be made dilute or concentrated by altering the ratio of acid to water.--G N Frykman 17:52, 11 August 2006 (UTC)

Well, the question is ambiguous. Depending on the circumstances, titration could measure either "strength" or concentration. --Bmk 19:54, 11 August 2006 (UTC)

The strength of the acid - how much it ionises - would be calculated by conductivity measurements. Titration will only tell you the concentration of the acid, and won't tell you whether it is strong or weak.--G N Frykman 09:41, 12 August 2006 (UTC)

Thermodynamics

Hi, I have a question with a bet I am trying to settle, I cannot find the info on wikipedia. Is it possible for a fridge/air conditioner ect to produce more cold then heat? I thought a thermodynamics law stated that it was impossible for it to produce a net cold? Any answers? If so could you provide the law or some reference? Thanks

Hanez

A refrigerator merely sucks heat energy from the interior and dumps itoutside the case. You also have the heat produced by the compressor. So the answer is : it produces more heat than cold!--Light current 17:19, 11 August 2006 (UTC)

So, yes, Hanez, you are correct, it would violate the laws of thermodynamics for any device to lower the temperature of the universe. StuRat 18:08, 11 August 2006 (UTC)

So why do you need a fridge that big?--Light current 18:12, 11 August 2006 (UTC)

Maybe so you can put stars inside the fridge to induce cold fusion ? :-) StuRat 18:24, 11 August 2006 (UTC)

Stars are already (hot) fusion reactors 8-)--Light current 18:31, 11 August 2006 (UTC)

So cool them down, and then you have cold fusion, right ? :-) StuRat 23:53, 11 August 2006 (UTC)

Thanks for the responses. How about heat neutral? Is it possible for a dehumidifier or a fridge ect to produce the same amount of heat as it does cold? Or should it always be producing more heat than cold?

That would require 100% efficiency, which never exists in the real world. StuRat 23:53, 11 August 2006 (UTC)

This concept will be much easier to understand if you stop thinking of "cold" as a substance. The best way to think of a refrigerator is an engine that works between two heat baths of different temperatures by taking in external energy. See heat engine. A refrigerator is a heat engine working in the opposite direction. --198.125.178.207 00:53, 12 August 2006 (UTC)

It's actually pretty humorous that the only thing air conditioners do is produce heat overall =D --mboverload@ 01:24, 12 August 2006 (UTC)

please do not pull tongues here! thans

--Light current 04:34, 12 August 2006 (UTC)

Soda Water

I drink a lot of soda water. I do so to help me prevent from drinking soda. But also cause water is boring and I want to keep hydrated. So, for the latter reason, am I really hydrating myself with soda water? Here are the ingredients on one particular bottle:

table salt, sodium citrate, sodium bicarbonate, potassium bicarbonate, potassium sulfate, or disodium phosphate

Also, does milk hydrate? Thanks!!!

THe question is: are any of those substances diuretics?--Light current 17:23, 11 August 2006 (UTC)

What do you mean by "hydrated?" If you simply mean "not thirty" than pretty much anything with water in it will do. When energy drink makers talk about "hydration," it's a marketese way of refering to osmotic pressure. When you sweat, you give off not just water but salt. Your body needs to maintain a pretty stable ratio of both, so drinking pure water is not ideal. Electrolytes (ie, salt) help. If you're running long races or hiking in the desert, you need to care about this. Otherwise, it doesn't really matter. --Pyroclastic 17:34, 11 August 2006 (UTC)

Why cant you be hydrated even if you are thirty?--Light current 17:47, 11 August 2006 (UTC)

Anything with water in it will "hydate" you, it isn't that scientific. — [Mac Davis] (talk)

Purified water

On the North American cooking show Good Eats, in an episode on making stock, the host Alton Brown mentioned that distilled water was too pure to be good for dissolving the collagen and flavor compounds that are necessary for good stock. I was under the impression that very pure water is "hungry" to dissociate into ions and is therefore a very good solvent, not a poor one. Am I mistaken, or is Alton? --Ginkgo100 ^{talk · contribs · e@} 17:48, 11 August 2006 (UTC)

Pure water is an excellent solvent, but is reckoned not to be very good for making tea, for example. This is possibly due to the lack of dissolved air - boiling the water to distil it gets rid of most of the dissolved air. The degree of ionisation of water itself is always very small (it's called the ionic product of water) but it is a wonderful solvent for ionic substances.--G N Frykman 17:57, 11 August 2006 (UTC)

Yeah I think its bad to drink pure (deionised) water. It needs some minerals (or whisky).--Light current 18:16, 11 August 2006 (UTC)

Well, stock isn't intended as a beverage, but as a food base for sauces and soups. The idea is that some types of water will be better at dissolving substances in the meat, bones, and vegetables and therefore produce a higher quality stock. If the problem is dissolved air, would aerated distilled water be as effective as tap water or artesian water? --66.7.182.48 Ginkgo100 ^{talk · contribs · e@} 19:30, 11 August 2006 (UTC)

I say Alton Brown is just wrong. It doesn't matter. Once you dump the bones, meat, and vegetables in it's not "purified" anymore anyway. I will say that buying distilled water for food purposes is a waste of money. --GangofOne 19:51, 11 August 2006 (UTC)

His claim was that there was a negative benefit to using distilled water (as is not usually the case in cooking, since you want the purest ingredients possible) since normal water has a baseline of impurities that works toward bringing more flavor out of the stock. Also, saying that using purified/distilled water for food use is wasteful, is a matter of complete opinion as many culinary experts and food connoisseurs would argue the opposite and can easily tell the difference in food prepared with purified water versus typical tap water.

There is a well-known (among protein biochemists) phenomenon of "salting in" proteins. First google hit: "Initial salting in at low concentrations is explained by the Debye-Huckel theory. Proteins are surrounded by the salt counter ions (ions of opposite net charge) and this screening results in decreasing electrostatic free energy of the protein and increasing activity of the solvent, which in turn, leads to increasing solubility. This theory predicts the logarithm of solubility to be proportional to the square root of the ionic strength." (source) For protein solubility, the pH of the water can also be important.
--JWSchmidt 22:35, 11 August 2006 (UTC)

but that is irrelevant, once you dump meat etc in the water (full of ions etc), you no longer have pure water. i'd say the amount of ions in the water (generally on the ppm level for most ions) contributes only the tiniest amount to the amount of ions in stock (which will be much much more). i'd say your cook is talking smack. Xcomradex 02:08, 12 August 2006 (UTC)

British bombing plot explosives ingredients

Reportedly (I am not too impressed by the news media's facts), the bombers planned on using liquid mixtures in British sports drink bottles to make an explosion. Does anybody have any guesses to whether or not this is true, or what chemicals they were planning on using? — [Mac Davis] (talk)

There was a demonstration on the TV last night by a Professor of chemistry (or something like that) who took some simple ingredients making a mixture of 200 ml or so. He placed this on top of a (5mm?) steel plate, ignited it, and it made a neat hole about 30mm across. Draw your own conclusions.--Light current 18:43, 11 August 2006 (UTC)

So basically if the self destruct button on the plane is hidden behind a 5mm steel plate, you can punch hole in it and press the button. Otherwise you'll need something better. Philc _T^E_C^I 21:09, 11 August 2006 (UTC)

The article on the 2006 transatlantic aircraft plot mentions some possible mixtures. Some of the articles listed in the "see also" section describe what has been used in other strikes. Weregerbil 18:45, 11 August 2006 (UTC)

I read somewhere that a mixture of acetone and concentrated hydrogen peroxide was likely. --Pyroclastic 18:58, 11 August 2006 (UTC)

I thought of this as a possibility, but I don't know. --Bmk 19:58, 11 August 2006 (UTC)

Nitroglycerin has been used by terrorists in at least one aircraft bombing, although it did not succeed in destroying the aircraft. If carefully positioned in a vulnerable location, and possibly combined with other components to generate shrapnel, I'm sure this could potentially be used to cause a crash. --Yummifruitbat 23:13, 11 August 2006 (UTC)

Look up binary explosive. Also keep in mind that aircraft skin is made of aluminum and is a lot thinner than that 5mm steel plate. Something that can blow a one-inch hole in that plate can create a hole five feet across or more in an airplane. --Serie 21:51, 11 August 2006 (UTC)

I have no idea how aircraft keep a balance between internal and external air pressure. Would it be possible for a gas generator of the type used in airbags to produce so much gas in a short period of time that the skin of an aircraft could rupture and pop open? --JWSchmidt 22:43, 11 August 2006 (UTC)

I think such a device would need to produce a phenomenal amount of gas - remember that an aircraft fuselage is itself a pressure vessel and is designed to withstand a considerable pressure differential. I think causing a rapid (i.e. explosive) decompression would be more feasible, particularly since this has the potential to incapacitate the crew even if the aircraft is not destroyed by the explosion. --Yummifruitbat 23:13, 11 August 2006 (UTC)

bearing in mind a fire on board an aircraft is a rather serious issue, i'm sure simply spreading 100 mL or so burning flammable liquid around could cause a fair amount of disruption. and 100 mL nitroglycerin would cause a tremendous amount of damage, given (a) it is 1.5x more powerful than TNT, and (b) it has a reasonable density. so 100 mL nitroglycerin would be about 117g, which would be equivalent to around 175.5g TNT. for comparision, in a hand grenade there is about 180 g Composition B. so you could certainly do a lot of damage to a soft aluminium shelled aircraft. Xcomradex 02:03, 12 August 2006 (UTC)

just a thought, i bet a chemically aware terrorist could make some pretty clever bombs, say a concentrated solution of diazomethane or neat phenyldiazomethane. i imagine its the last thing sensors are looking for. or even something around organic azides, eg diazidomethane. i imagine we aren't getting the whole story out of the respective govts, especially since a lot of sensitive compounds (eg TATP?) become a lot less sensitive in solution. Xcomradex 02:24, 12 August 2006 (UTC)

and i am entertaining the thought of panclastite type explosives being what was going to be used, easily prepared from relatively inert and readily availible ingredients. Xcomradex 02:30, 12 August 2006 (UTC)

Instead of bombs, Andrew Sullivan [16] suggests instead that the weapons might be the "terrorist breakthrough" device called a "mubtakkar" that quickly evolves a large quantity of hydrogen cyanide gas. Via a report in Time magazine [17]. -Wfaxon 07:38, 12 August 2006 (UTC)

Speed of Smell

Is there any way to quantify the speed of smell? Here is a crude example but its the first to come to my mind; sometimes when I fart, I smell it right away...other times it takes a while. Well, not that I think about it wind, humidity prolly are factors in this. But is there anyway, in like a controlled in environment, that the speed of smell can be quantified?

It just depends how fast the smelly molecules are travelling. THis of course depends on the air velocity in the vicinity. If you were to fart downwind, the smell would travel woth the wind (hopefully) at its speed. I predict this question will attract a great many comments (some funny, some not).--Light current 18:47, 11 August 2006 (UTC)

Brownian motion ? :-) StuRat 23:46, 11 August 2006 (UTC)

I guess the speed of a fart would be the speed of any air currents that are present combined with entropy in the form of Brownian motion. Weregerbil 18:51, 11 August 2006 (UTC)

Yes I think you are correct. Plus of course the exit velocity from the offending orifice?--Light current 18:53, 11 August 2006 (UTC)

Well this is an odd question. Well if we're talking about the time it takes for the " smell " to reach you that would be depend on the speed at which the particles involved move. You should note that a cloud of particles isn't a " smell ", it becomes one when it interacts with the receptors in your nose. I think Olfaction might be a good read for you PvT 18:54, 11 August 2006 (UTC)

Besides air currents, the main factor affecting the "speed of smell" is simple diffusion. (A question for others with a better understanding of physics: Is there a known rate of diffusion in still air? Would it depend on air pressure?) A more concentrated odor will seem to travel faster than a less concentrated one because the threshold of molecules necessary to detect it will reach the nose faster. --66.7.182.48 Ginkgo100 ^{talk · contribs · e@} 19:27, 11 August 2006 (UTC)

I believe small molecules diffuse faster, and diffusion speeds up at higher temps and lower air densities. It some cases, the rate of diffusion in air is amazingly high. StuRat 23:44, 11 August 2006 (UTC)

For biomolecules, which are relatively heavy compared to air, stray air currents (caused by such things as breathing, moving, ventilation, farting, etc) are usually much more efficient at moving odors around than actual diffusion. In perfectly still air an odor could take many hours to cross a room. In practice people often use an effective diffusion rate which is really not diffusion at all, but an average rate of transport due to all the stray air currents. Dragons flight 00:05, 12 August 2006 (UTC)

I would have thought there are a few factors involved. Firstly, the volatility of the odor source, then the considerations described above on the air currents carrying the volatiles to the nasal epithelium. Then you have to consider the number of molecules required to activate the number of neurons required for our noses to recognise a smell. The next consideration is the rate at which the olfactory neuron can transduce the binding of the odor to its receptor, into an action potential (this is pretty quick when tested experimentally). Then you have to consider the neural circuitry (the details of which are currently unknown) as the activated olfactory neurons project to their glomeruli in the olfactory bulb and pass the signal on to mitral cells, which in turn project to regions of the cortex. Once there, we recognise the "smell". One would think the speed of the signal along the neural circuitry would be pretty repeatable, thus the variation would most likely be at the level of odor detection, reception and transduction, especially considering its know we undergo adaptation to odors (though the mechanism not fully understood). Rockpocket 01:52, 12 August 2006 (UTC)

We used to perform a simple experiment for our Year 9 pupils (UK: 13-year-olds) in which we took the lid off a gas jar of hydrogen sulphide in one corner of the laboratory, and got the pupils to note at what time they could detect the smell, and plot iso-smell (?) contour lines. It used to take about 20 minutes for the smell to get from the front to the back of the laboratory - which was way too fast for the theoretical speed of diffusion of hydrogen sulphide. There were many factors to consider, of course - the fidgeting boys, the heat each one was giving off, air currents from under the door and so on. When hydrogen sulphide became politically incorrect, as it were, we used a squirt of lemon-fragrance air freshener. --G N Frykman 09:34, 12 August 2006 (UTC)

Speakers

Can you assume that speakers are producing sound within the limits of their construction if there is no sound distortion? Or would it not be unreasonable to expect a speaker burst after cranking the volume a bit too high, even if it was producing clear sound just before bursting?  freshofftheufoΓΛĿЌ  19:44, 11 August 2006 (UTC)

I would say : yes--Light current 04:54, 12 August 2006 (UTC)

Without much knowledge about the science behind speakers, I would say no. --Proficient 13:53, 12 August 2006 (UTC)

Monogamy

As I was reading Brian Skyrms' book Evolution of the Social Contract and as he was discussing the evolutionary fitness of various strategies of division of a cake (greedy (2/3) vs. just (1/2) vs. modest (1/3)...) I wondered how monogamous relationships affect the evolutionary fitness of a species. On a naive level it seems that monogamous (especially lifetime monogamous relationships) would decrease the genetic variation of a species' off-spring, which seems (at least on my understanding of evolution) decrease the fitness. But likewise, if monogamy in that species is particularly helpful in raising well-adjusted adult members then that increases the fitness of the off-spring. Does anyone know of any semi-technical (or even technical, I guess I can attempt to read technical articles even though my major is philosophy) material on this subject? I'd imagine if you could find a species with monogamous relationships and a closely related species without that type of relationship, then you could get a beautiful study on how monogamy affects the evolutionary fitness of a species (insects would be great given their short life-time). And if my admittedly naive understanding of the complexities of evolution is wrong, then please point this out.--droptone 20:45, 11 August 2006 (UTC)

You should also factor in the venereal disease spread by polygamy. StuRat 23:38, 11 August 2006 (UTC)

There has been a significant amount of research on monogamy using rodents, for example, see: Prairie Vole. You might also be interested in this. --JWSchmidt 00:13, 12 August 2006 (UTC)

The thing is, long-term pair bonds for the purpose of raising offspring does not require monogamy. IIRC animal studies have shown that many of the animal species that supposedly mated for life had paired females who 'stepped out' with other males (bald eagles were an example they gave). Furthermore, another thing I read (sorry, don't have links and too lazy to look) said that something like 50% of Europeans with royal blood had DNA that indicated unknown paternity somewhere in their ancestry. Aaaand... it's the opinion of some paleo-sociologists or whatever they're called that this explains the evolution of the 'Alpha' vs 'Beta' males; 'cavewomen' chose Alpha males for their ability to protect and provide, but while the Alphas were out hunting, they were canoodling with the Beta males who were hanging around the camp. Remember, the postman always rings twice. Anchoress 00:21, 12 August 2006 (UTC)

The Strange Case of Diabetes, Genetics, and the MP

Recently my MP Dr Ian Gibson (who's a nice bloke, for a politician) said that a rise in diabetes in Norfolk may be due to inbreeding[18]. Now, naturally, us in Norfolk were not too happy about being portrayed as a bunch of inbred hicks, and scientifically I would question if Norfolk actually is significantly more inbred in this day and age than anywhere else in the UK. Dr Gibson later said his remarks were not meant to cause offence: he meant the term in a "scientific" sense (he has a degree in Genetics), which I guess means that he meant "the rise is caused by a small genetic pool" rather than the more unscientific and offensive "the rise is because my constituents are incestous". But I wonder if he's not using his badge as a geneticist to say "I didn't mean to offend, I meant something completely different because I'm a Scientist." Sorry for the long-winded question. Sum0 21:58, 11 August 2006 (UTC)

I read what Ian Gibson said and I think he was commenting on type 1 diabetes in much the same way that geneticists would normally discuss the possibility of a genetic basis for a disease. I doubt if he entertained any thoughts about incest in Norfolk. There can be a founder effect leading to high rates of certain genetic diseases is a population without any incest in a population. --JWSchmidt 22:17, 11 August 2006 (UTC)

I read about this story myself this morning and felt a bit sorry for Dr Gibson. Geneticists, among whose number i count myself, talk about "inbreeding" and "outbreeding" in a very matter-of-fact way, without any negative connotation the the general population may attach to the terms. Lab mice strains, for example, are divided into inbred and outbred lines, and these have implications on their fitness and use in disease models. His major mistake IMHO was, when referring to humans, was not using a less emotive term such as consanguinity, if indeed that was his point. As an aside, and at risk of offending our East Anglian friends, i used to live in rural Suffolk and remember as a child an elderly neighbour telling me how she never travelled more than 30 miles from her village until the age of 25, by which time she had already met her husband and had children. She also told me that people used to know which nearby village an individual was from based on their villiage characteristic, such as a squint, polydactyly or big ears. Of course, this is just the testimony of an old woman, but it did make me think Gibson has a point. Rockpocket 01:31, 12 August 2006 (UTC)

Camera Zoom

Are there any cameras where the zoom mechanism is internal to the camera body, so that the final (first?) lens remains stationary? (I mean on normal commercial cameras, not wacky specialist ones). -- SGBailey 22:18, 11 August 2006 (UTC)

wow that would be cool..Wjlkgnsfb 02:58, 12 August 2006 (UTC)

Yeah! The Kodak EasyShare V570 has an internal zoom mechanism. --jpgordon^∇∆∇∆ 03:26, 12 August 2006 (UTC)

See also digital zoom (which is not true zoom) and click on "what links here" for a list of cameras.--Shantavira 06:52, 12 August 2006 (UTC)

Smoking and lung cancer

Okay, I managed to find in tobacco smoking that a person who smokes tobacco is 25 times more likely than a non-smoker to develop lung cancer, but I can't seem to find the answer to this question: what pecentage of smokers die of and/or are diagnosed with lung cancer? Better still, good reference desketeers, does anybody happen to kow where I could find to access the approxiamate pecentage of all common causes of tobacco smokeing-correlated death among smokers, seperate from non-smokers? A pie chart (I like pie) would be striking gold. Many thanks in advance. – ClockworkSoul 22:37, 11 August 2006 (UTC)

http://www.cancer.org/docroot/PED/content/PED_10_2X_Smoking_and_Cancer_Mortality_Table.asp

Unfortunately, this only has cancers, not other causes of death, but take a look at the "PAR" column. Lung Cancer has an 88% PAR, which means that out of 100 cases of lung cancer, 88 were caused by smoking.

Also, you may want to check out some NCHS resources like this :http://www.cdc.gov/nchs/datawh/statab/unpubd/mortabs.htm

there's a ton of CDC/NCHS/NIH data to wade through on mortality...

Glow sticks, who invented them

My six year old son and I would like to know the chemist or inventor of the glow stick.

Glen

Hello Glen. Our article doesn't seem to mention the inventor. However, this google cache suggests:

In the early 1960s, Edwin A. Chandross, a young chemist at Bell Labs in Murray Hill, N.J., was searching for a general way to explain chemiluminescence. Peroxides, with their potential to liberate large amounts of energy during some chemical reactions, seemed to be likely participants.

After a number of experiments, he found to his great excitement that oxalyl chloride mixed with hydrogen peroxide and a fluorescent dye produced chemical light. The efficiency was only about 0.1%, but it was the foundation from which sprang modern chemiluminescence. Chandross, unaware of the powerful potential of his discovery, never patented it.

At about the same time, chemist Michael M. Rauhut was manager of exploratory research at American Cyanamid in Stamford, Conn. He and his colleagues corresponded with Chandross about his oxalyl chloride chemistry, then went to work on the reaction--studying it and looking for avenues that would produce chemical light intense enough to be of practical use.

Rauhut and his colleague Laszlo J. Bollyky developed a series of oxalate esters. Ultimately, Rauhut designed a phenyl oxalate ester that, when mixed with hydrogen peroxide and a dye, gave a quantum yield of 5\--not as efficient as a firefly, but still brilliantly useful. They dubbed it Cyalume, and it became the trademark name for American Cyanamid's chemical light products.'

So there you have it, Edwin A. Chandross developed the chemistry and Rauhut & Bollyky applied it to make the first glowsticks. Rockpocket 01:10, 12 August 2006 (UTC)

Chemistry term

Hi

I've been trying desperately to remember a particular term I heard used a week or so ago in a 3rd year chemistry lab. We had made an oily substance from beta-pinene, and had it sloshing around in an aqueous solution as a blob kind of thing. The oil was still liquid because solvent was 'dissolved' in it, so we mushed it around with a glass rod. This was meant to push the solvent out of it. It turned to chewing gum consistancy, then solid.

Finally, I get to my question: the working it around with the glass rod had a term to describe it. Maybe it was something like titilation... anyone have any ideas what this word actually was?

Thanks for your help

Aaadddaaammm 01:14, 12 August 2006 (UTC)

Perhaps agitation? I think agitation is usually used for liquids, not gummy substances, though. --Bmk 01:18, 12 August 2006 (UTC)

Sorry - didn't read carefully enough - I guess it was liquid while you were ----itating the solution. Perhaps it was agitation then. --Bmk 01:22, 12 August 2006 (UTC)

Wow thanks for the quick reply, but that's not the word... We "X"ed the liquid until it became gummy and then kept "x"ing it until it was completely solid. It was a really weird word that I've never heard before Aaadddaaammm 01:26, 12 August 2006 (UTC)

Based on your guess, could it be Trituration? Rockpocket 01:35, 12 August 2006 (UTC)

YES! Thank you! Wikipedia comes to the rescue again! I'm impressed! Aaadddaaammm 01:37, 12 August 2006 (UTC)

Well, we're not really an encyclopaedia, but a small community of smart guys, here on the Reference Desk.

Color in Complete Darkness

I clicked the random article button, as I usually do, to find new topics of interest. An article came up about how the color perceived in complete darkness is actually lighter than the color seen as black in a lit area because the brain relies partly on contrast, rather than solely on absolute color, to differentiate between objects and colors. A name was given for the color seen in complete darkness, and I should like to know what it was, but I can't figure out how to find the article. It would be greatly appreciated if an answer, or more helpfully, the actual article, could be sent to email redacted. Thank you,

Maverick —The preceding unsigned comment was added by 64.12.116.74 (talk • contribs) 01:42, 12 August 2006 (UTC)

De nuit tous les chats sont gris. (Did I get that right?) --Trovatore 01:47, 12 August 2006 (UTC)

La nuit, tous les chats sont gris. --Lambiam^Talk 06:46, 12 August 2006 (UTC)

Even though complete darkness wouldn't have a color because color is a wavelength of the electromagnetic spectrum... yeah, I can't help you. — [Mac Davis] (talk)

Yeah. you must have light to percieve color. So there is no such thing as color in complete darkness. You may want to think a bit more about what you are asking, perhaps you mixed some facts. pschemp | talk 05:37, 12 August 2006 (UTC)

If you've forgotten the title of an article you visited recently, try looking through the history list of your browser. Could it have been Purkinje effect or scotopic vision?--Shantavira 07:01, 12 August 2006 (UTC)

Could it be eigengrau? Adambrowne666 11:53, 12 August 2006 (UTC)

Interesting. --Proficient 14:00, 12 August 2006 (UTC)

um if this is random color seen in perfect darkness due to the optic nerve firing or molecules in the cones (thus nothing is really actually seen) this statement in the article "the night sky looks darker than eigengrau because of the contrast provided by the stars." is odd since the night sky is nothing close to being in perfect darkness. Maybe the article needs some help.pschemp | talk 14:18, 12 August 2006 (UTC)

The claim is that the night sky with stars appears darker than eigengrau, not that the night sky is "perfect darkness." digfarenough (talk) 17:09, 12 August 2006 (UTC)

central dogma

what are the situations where central dogma are not obeyed

Assuming you are referring to the Central dogma of molecular biology - (where DNA becomes RNA becomes protein) - then any retrovirus in the process of replicating violates this dogma. Raul654 04:51, 12 August 2006 (UTC)

Another crypsis question

Can anyone tell me the name of the creature, I think it's a spider, that has evolved to so resemble the creatures it preys on, I think it might be ants, that it is all but indistingishable from them?

Thanks, Adambrowne666 05:30, 12 August 2006 (UTC)

See our article on Ant mimicry. --Lambiam^Talk 05:43, 12 August 2006 (UTC)

Thank you, perfect. Adambrowne666 06:33, 12 August 2006 (UTC)

minto engine

  i want to know more about

Uhh?--Light current 05:40, 12 August 2006 (UTC)

Do you mean the Mentos eruption? InvictaHOG 05:45, 12 August 2006 (UTC)

The user probably means the heat engine; see this reference. Could it be that this is the same device as the "Minto wheel" mentioned in MythBusters (season 2)? --Lambiam^Talk

Drugs producing synaesthesia

Sir, could you, please, elaborate a list of drugs that produce synaesthesia with some limited additional information about them? Thanks.

I don't believe any chemicals produce true synaesthesia, which is a specific neurological condition. Some chemicals, the most well-known of which is LSD, are said to produce something akin to synaesthesia, though. Psychoactive mushrooms might produce such an effect (not sure) or perhaps peyote or other cacti, but I don't know much about those. In general though, I think it's safe to say that no chemical is going to alter your brain in such a way as to give you true synaesthesia. digfarenough (talk) 17:15, 12 August 2006 (UTC)

Insecticides --- as Preservatives

Hello! Why do soft-drinks companies use insecticides in their products as preservative? Are there no alternatives to this? Often, it is beyond permissible limit... and regular consumption of which may lead to fatal disease. I want to know why can't this use be discarded altogether... There must be some other chemicals(i don't know though),which can replace insecticides. Or is the alternate one too expensive for the companies to use (it will definitely prevent them from making those dazzling ads.)??? Thanks,--Pupunwiki 09:00, 12 August 2006 (UTC)

unless you can produce a specific example, i'd say they don't. Xcomradex 09:40, 12 August 2006 (UTC)

This could be about the India cola thing ([19], see google news for more). There are a number of possible explanations: there is a farm within some kilometers of a cola bottling plant, and microscopic amounts of insectiside get carried around by wind. And/or local cola manufacturers have found a neat trick to kick Pepsi and Coke in the groin by spreading rumors. You'll probably eat more pesiticide in your daily bread and milk because they are produced on farms that handle pesticides. Weregerbil 12:44, 12 August 2006 (UTC)

Yes, this is concerning the India-cola thing. It's evident from here. .Looking forward for a better answer... Thanks,--Pupunwiki 13:37, 12 August 2006 (UTC)

an answer to what? he's already explained they do not add pesticides as preservatives. Xcomradex 13:43, 12 August 2006 (UTC)

Weregerbil is correct. Pesticides have been used heavily by indian farmers for a long time. As a result, there are significant levels of pesticides in ground water throughout India. Therefore, when Coca Cola and Pepsi add Indian water to their product, it contains some pesticides. You must have misread whatever you read if you think that they purposefully put pesticides in their products as "preservatives". It's a contamination issue. And by the way, you might be a bit more polite to people who have taken the time to answer your question. --Bmk 14:21, 12 August 2006 (UTC)

Sorry,I didn't mean to hurt anyone... Actually, both the print & electonic media in India have mentioned of pesticides being used as preservatives ... Like-   Dr. Ashish Tiwari of Bombay Hospital said, “These pesticides are used by the cola companies to preserve their products for a longer period as compared to other countries. ” / Some city medical experts believed the pesticides were in the form of preservatives that ensured a longer shelf life for the products, but this too was harmful for health they said.(as seen here).Though,the cola companies diagree to it. Even though, a question arises : Why can't the water used, be filtered properly during processing the products? These apart,I really want to know what are the preservatives used worldwide ? Again,if i have been rude to anyone untentionally, I apologize. --Pupunwiki 17:51, 12 August 2006 (UTC)

Vicodin HP Tabs vs. Lorcet 10/650

ṬìňàHi, I have a pretty simple question if anyone could be of assistance. I have used search engines but haven't been able to find out anything helpful. I truly appreciate any assistance that someone would offer. My husbands' Doctor has been prescribing Lorcet 10/650 for his spinal problems for quite some time now. He has no problem with this medication as he normally only takes 1/2 tablet when his pain is difficult. He has never been one to take much medication but will;when necessary, take only 1/2 of a pill when needed. He doesn't have a high tolerance for pain meds but has been doing okay with the Lorcet. However; his last Dr. appt., he was written the exact same prescription, but upon having it filled at the pharmacy, we noticed the tablets looked different. We just assumed this was some form of generic. However; my husband was suffering with his pain a little more than usual last night and he took one (1) of the "different" tablets. It wasn't long before he began sweating, feeling nauseated, difficulty breathing, and finally vomiting. Now; I have looked at one of his prior prescription bottles vs.the new one and it does have different name. The new, white tablet has "Vicodin HP" whereas the older ones have Lorcet 10/650. It has now been quite a few hours and he still feels pretty bad. Is there anyone who could tell us what the HP stands for and what is the difference in the two? I know there has to be something different between the two and I sure do appreciate any assistance you could offer. Thanking you in advance, TH