Wikipedia:Reference desk/Science

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A tight budget, no patience and a stack of reading to scan so it can _still_ be read.

What sort of page scanning speed can one expect given the following:

• A fairly low-end scanner.
• A resolution good enough to give an image able to pick up average newsprint font size and reproduce it so it's easily readable to the eye (no OCR involved).
• A desire not to have to be very careful about lining up each page on the flatbed.

Essentially, it occurs to me I have lots of reading material I'd like to get rid of (to give me more room and for profit) and I'm wondering how quickly I could scan through the entirity of an old magazine but keeping the filesize/time down. --bodnotbod 07:18, 15 October 2005 (UTC)

Another consideration. How much time would it cost, how much is your time worth (assuming that time is money) and how does that compare to the cost of the space you'd need to keep the magazines. If you don't need to access them regularly you could stow them away in a box so that it doesn't effectively take up space (depending on your living conditions of course). Let's say one scan would cost a half minute. That's roughly 100 pages per hour or one magazine per half hour. One average box of magazines would contain about a hundred. That's 50 hours. Assuming you value your time very low, at 5 euro per hour. That would be 250 euro. How long can you store one box for that? Assuming that is one month's rent for a house that is 30x30x30=10.000 times bigger than the box. So you could store the box for 10.000 months for that price. That's well over 10 lifetimes.

This is assuming you can't do anything else while you're scanning, which is pretty much the case. Believe me, I've tried this sort of thing - even doing the scanning while working on the Wikipedia reference desks wouldn't really work. Another option would be to build a contraption that turns the pages and does the scanning automatically, like the ones used by libraries that are digitising their books. Or maybe you could hire some time on one of those machines. Ask at a library. Who knows. DirkvdM 09:41, 15 October 2005 (UTC)

If I were going to do this, I'd want to score a scanner that did two-sided scanning and had a sheet feeder like most copy machines have. That way, you could just cut all the pages of the magazine off of its binding and shove 'em in the sheet feeder. However, we're beyond "fairly low-end" scanners at that point. Garrett Albright 17:01, 15 October 2005 (UTC)

Bear in mind you talking about something potentially illegal here. The publications are copyrighted. This means you purchased ONE copy. If you scan the media into computer, then dispose of the original dead tree copies, you now have created two copies (even though you got rid of one, either by give away or sale), perhaps #3 as backup, which violates you bought one. You could physically destroy the original media, and be in compliance in spirit but then if the copyright police find you in possession of the scanned copy, you'd need to prove you destroyed the original, which can be difficult to prove without the destruction evidence. AlMac|^(talk) 19:06, 15 October 2005 (UTC)

Well, that would be inherently impossible to prove. But isn't one allowed to make at least one copy for oneself? And does that depend on the country or is there an international law on this? And anyway, would the copyrights police (is there such a thing?) really be bothered? DirkvdM 08:46, 16 October 2005 (UTC)

In the US, I believe you have the right to one backup copy, which would be the scanned magazines. However, I am not a lawyer. Superm401 | Talk 20:28, 16 October 2005 (UTC)

• Hmm, well I think DirkvdM has put me off the idea, I think I imagined that you could get a cheap scanner know that would scan a page in a couple of seconds, such is the rate of progress in some areas. As for the copyright, whilst I try to remain scrupulous about such things for Wikipedia, I wouldn't be averse to, how can I put this, explore the current boundaries of what one is allowed to do with one's reading material in the safety of one's own bedroom. No, wait: that's not what I meant to say at all. Thanks all. --bodnotbod 21:15, 17 October 2005 (UTC)

How can you tell if a plant likes to have sex?

It takes hookers for a ride!!!!!!!!!!!111

Any help would be gratefully received.

Have a look at the article on plant sexuality. For an example of a plant that is unisexual (which means it has a "reproductive structure that is either functionally male or functionally female"), see begonia. David Sneek 09:24, 15 October 2005 (UTC)

For some nice pictures, see stamen and carpel (respectively the male and female sexual structures in plants). Physchim62 09:29, 15 October 2005 (UTC)

Flowers are the most reliable indication to discriminate between species (if they have flowers at all), so I assume the same will be true for discriminating between sexes. But flowers differ enormously between plants, so I don't think there will be many general indicators. The most obvious one is that male flowers produce a powdery stuff called pollen, but that is only during a very short time in the lifecycle of the plant. Other than that, I know that in hemp the female leaves are usually somewhat braoder than the male leaves, but that also varies between varieties of one species, so it's only a very vague indicator unless you know which variety yo're dealing with. DirkvdM 09:57, 15 October 2005 (UTC)

Fruit is only produced by female plants. It is defined as the ovary of a female plant, containing either fertilized or unfertilized seeds (ova). However, there are other things that look very much like fruit, produced by other plants. StuRat 22:42, 15 October 2005 (UTC)

I do know that if you crowd dope plants together they will produce largely male plants but a single plant grown on its own will more often than not grow into a female. The logic behind it is because a crowd of females will drop their seed in an area already populated by dope plants. The result is the species does not spread far. However if a seed does find its self on its own and thus in an area not populated by dope plants it would be best to turn into a female to catch wind blown pollen from the group of males. We are not talking huge distances here but what the heck who's in a hurry :-)--Eye 21:17, 15 October 2005 (UTC)

I suppose you're talking about hemp here. I don't think you can really say they determine their sex based on the circumstances. Hemp (dope or not) is a hermaphrodite, meaning a female plant can produce male flowers (and vice versa I believe). They do this when, after a while, they're still not pollinated. And the much stronger reason is that if they didn't they might not get any offspring at all. DirkvdM 08:54, 16 October 2005 (UTC)

Electricity

If electricity is defined as a flow of particles, electrons or whatever does this imply it has some sort of volume? If so what volume is reduced when electricity flows and how was it created. I have some understanding of comparisons with hydraulic systems when talking about electrity flow and pressure.60.229.174.15 10:48, 15 October 2005 (UTC)

In hydraulic terms, electricity is essentially incompressible. However some materials do change volume when electricity flows through them: see electrostriction. Physchim62 14:21, 15 October 2005 (UTC)

Thanks. But I am still having trouble with this volume and substance thing

bascially, assume that electrons don't take volume. electrons are way to tiny to take up any space and remember that we're dealing with a sub-atomic phenomenon. electrons do take some volume but it is so little and it does not result in any measureable effect. The most of the volume of anything is made up mostly of empty space caused by electrostatic repulsion... Sasquatcht|c 08:12, 16 October 2005 (UTC)

While electricity does "flow," it only has "volume" on a trivial level. The rate of the flow, i.e., the number of electrons traveling past a given point per second, is measured in amps, while the pressure of the flow is measured in volts, but nothing more similar to volume than that exists with regard to electricity. --Frostyservant 17:09, 22 October 2005 (UTC)

Mass of bacteria in the human body

Does anyone know what mass fraction of the human body is composed of bacteria? That is, if you took all the bacterial cells out and weighed them, how much mass would that be compared to the mass of the whole body? —Keenan Pepper 16:59, 15 October 2005 (UTC)

Just to clarify, I'm talking about a normal, healthy human, although I think you'd have to have quite a bad infection to significantly add to the mass of normal bacteria. —Keenan Pepper 18:17, 15 October 2005 (UTC)

It depends on whether you include Mitochondria. These were originally proteobacteria, a major group of bacteria that started living in symbiosis with other lifeforms so early that most now have hem in every cell of their body, where they take up 25% of the internal fluid of those cells. And since we consist fully of cells and fluid constitutes the major part of our weight you could say that they constitute some 25% of our weight. (Although I'm not sure every cell has them, such as in bones.) But that's probably not what you were thinking of. DirkvdM 18:33, 15 October 2005 (UTC)

Oh right, I didn't even think of that. But besides mitochondria, what's the mass of all the "true" bacterial cells? Bacteria in the human body says there are about 10 times as many as human cells, but what is their average mass? —Keenan Pepper 18:43, 15 October 2005 (UTC)

Using the article you linked to above and this webpage [1] you can calculate 1x10¹⁵ x 1x10^-12g = 1x10³g or 1kg. I think bacteria can range in weight a fair bit. No idea how close to right this is. --Martyman-(talk) 23:38, 15 October 2005 (UTC)

Nearly all the bacteria are topologically outside our body: on the skin, and in the gastrointestinal tract. Intestinal contents do not acquire a large bacterial component until they reach the colon, but bacteria do represent a substantial fraction of feces (though less than half of the fecal mass). So maybe a kg worth of bacteria in your colon at most, probably less. While we have zillions on our skin and in our mouth, they would probably not add up to more than an ounce (30 g) by themselves. There should be no significant amounts amounts of bacteria anywhere else in your body. alteripse 00:17, 16 October 2005 (UTC)

Even when you're sick? Are we talking about about bacterial mass of, say, one percent of the human body here? (Probably not, I guess.) DirkvdM 08:58, 16 October 2005 (UTC)

If you exclude the bacteria on skin and hair, in the mouth,, and in the gut, there should be close to zero bacteria anywhere else inside you. When you are sick, bacteria may proliferate, but even with an abscess full of pus, most of the mass of the pus is necrotic tissue and immune cells and fluid, not bacteria. The bacteria in your colon might be around 1% of your body mass, but those elsewhere probably do not exceed 0.001% of your body mass. You will die long before an infection in your blood produces another kg of bacteria. alteripse 16:43, 16 October 2005 (UTC)

Overheated Glass

What happens when glass overheats? Does it expand? What are the hazards of a glass pot left on a hot stove, and would it be safe to pour water in it?

If you heat glass to a high enough temperature (1000-2000°C), it will simply melt. Your stove probably doesn't get anywhere near that temperature, so your glass pot can't "overheat". Pouring cold water in it is a different story, because glass does expand when heated, so a rapid change in temperature may cause it to crack as some parts contract faster than others. —Keenan Pepper 17:23, 15 October 2005 (UTC)

Glass does of course expand when heated, and contract when cooled, which as Keenan Pepper explained, could cause cracking. However, if the glass was extremely hot(unlikely), the water poured could become steam and possibly cause steam burns. Superm401 | Talk 20:27, 15 October 2005 (UTC)

I've had a coffee pot crack because the glass has a different rate of expansion than the metal band around the neck of the pot. StuRat 22:35, 15 October 2005 (UTC)

Musical Statues

Why is it so difficult to remain perfectly still? If someone tries not to move a muscle, they end up twitching or shaking. Surely it should be easier to stay still than to move! smurrayinchester^{(User), (Talk)} 17:18, 15 October 2005 (UTC)

Nothing is ever still--Eye 17:31, 15 October 2005 (UTC)

Even when you're trying to keep some part of your body still, your muscles are pulling on it from different directions. If the muscles aren't perfectly in balance, it will move to one side or another. That explains why it's easier to keep your arm still if it's hanging at your side (muscles mostly relaxed) than if it's raised above your head (muscles pulling in opposition). Also nerves have a lot to do with it... —Keenan Pepper 17:33, 15 October 2005 (UTC)

An analogy that might help you think about this might be:

You and your friend are playing tug of war with a rope. Lets decide neither of you want to win but rather want to keep the rope perfectly still. If your friend pulls harder, you'll need to pull harder too; the same goes for pulling less hard. Will the rope be perfectly still? Probably not -- it will wobble back and forth while you both try to keep it still.

This is in a way what happens with your body. When you try and hold your hand still in a certain pose, it is actually using an entire groups of muscles that all must be in perfect balance. This is why you'll notice wobbles. However, if your hand is in a perfectly relaxed pose with very few muscles in use, you should be able to hold still without much problem. --Quasipalm 03:48, 16 October 2005 (UTC)

Also, muscles don't have a smooth/continuous force range - each muscle has a certain number of bundles controlled by a certain number of nerves. To maintain a precise force, some of the bundles have to relax for some of the time, which introduces small tremors. (The effect is more pronounced on the smaller muscles, which don't have as many bundles as larger muscles such as the gluteus maximus. For some reason I'm thinking of analog/digital signal conversion...) Tzarius 11:05, 21 October 2005 (UTC)

Web technology

I'm opposed. George 21:00, 15 October 2005 (UTC)

I agree. Web technology sucks. gkhan 23:15, 15 October 2005 (UTC)

Especially those new-fangled wiccas. Superm401 | Talk 07:50, 16 October 2005 (UTC)

No kidding, we should burn all wiccas at the stake! just like the old days... Sasquatcht|c 08:07, 16 October 2005 (UTC)

What the Wuck is a Wicca? DirkvdM 09:02, 16 October 2005 (UTC)

Earth and sun

How fast dose the earth spin around the sun? Name:aidan McCarthy Age:8

• The Earth takes one year to go around the Sun.
• The Earth takes one day to go around itself.

AlMac|^(talk) 19:10, 15 October 2005 (UTC)

The Earth revolves around the Sun once a year, and it's 150 million kilometers away, so the total distance it travels in one year is 2 times pi times 150 million kilometers, or almost a billion kilometers every year. That means its speed in relation to the Sun is about 30 kilometers per second. In other words, really really fast! —Keenan Pepper 19:14, 15 October 2005 (UTC)

The Wikipedia article on Earth has a lot more facts about the Earth, like how big it is and how much it weighs. —Keenan Pepper 19:18, 15 October 2005 (UTC)

The weight?? Don't you mean "mass"? Dismas|^(talk) 00:12, 16 October 2005 (UTC)

Well, it weighs something in the gravitational field of the Sun, right? That's why it's falling (accelerating) toward it. But you're right, I meant mass. —Keenan Pepper 01:35, 16 October 2005 (UTC)

Adian, you might be interested in our "WikiBook" titled Wikijunior Solar System which has a lot of information on the solar system and is written especially for children. Garrett Albright 04:15, 16 October 2005 (UTC)

The Earth does not take one day (as in 24 hours) to turn around its own axis. That's just the way it seems from the Earth's surface. Suppose the Earth would not turn around its axis. Then, over a year, you would experience one 'day' (as in a day/night cycle). Thus, there is always one day/night-day more than the amount of axis-rotations. DirkvdM 10:55, 17 October 2005 (UTC)

Minor astronomical nitpick: we should probably distinguish between a solar day and a sidereal day. The former is (roughly) how long it takes for the sun to return to the same point in the sky on successive days. The latter refers to the time for the Earth to turn once (360 degrees) about its axis; the sidereal day is about four minutes shorter than the solar day.

The sidereal day is important for astronomers, because any star–except for the Sun–will be in the same spot in the sky at the same time each sidereal day. A star that is overhead at midnight (solar time) in January will be overhead at noon (solar time) in July. TenOfAllTrades(talk) 14:48, 17 October 2005 (UTC)

MSN Messenger

Is it possible to figure out when your contacts come online?

• Apart from the message you get when a contact gets online? - Mgm|^(talk) 20:45, 15 October 2005 (UTC)

I am guessing they meant ot ask when they came online, 20 minutes ago or 20 hours ago ? I suspect it could be done if you when online when they came online, as a signal is sent to your computer. However, if you weren't online when they came online, no message is ever sent to your computer, which would make it a lot more difficult. StuRat 22:06, 15 October 2005 (UTC)

The popular Messenger Plus plug-in includes an event log (click Plus > Event Log Window) which shows when contacts come online, change their status, and go offline, all with times. --Sum0 23:18, 15 October 2005 (UTC)

Do note, however, that if you use this, DO NOT install the sponsor. --Pidgeot (t) (c) (e) 23:45, 15 October 2005 (UTC)

Muscular Force

Could someone please tell me what the average force exerted by the brachial muscles (the deltoid to the phalangeal adductors) on an object is?

Michael P. Barrett --86.128.76.18 19:58, 15 October 2005 (UTC)

• How much can you lift in a bench press? Multiply the weight in kilograms by 9.8 (or the weight in pounds by about 21.5) to get the force in newtons. Physchim62 20:12, 15 October 2005 (UTC)

Topology

An anon posted this message in WP:HD. I moved it to here. --User:Mdob (note: there are other messages too, move them to here if you have patience, thank you)

Regarding the metric space and topological group.

Question : Is metric space with group structure topological group?

Yes. A manifold (like an metric space) with group structure is a Lie group, and there is a equivalent definiition in terms of topological spaces. See Lie group#Alternative definitions --User:Mdob | Talk 20:13, 16 October 2005 (UTC)

PDF autocropping/rotating?

Are there any programs out there which can automatically rotate and crop PDFs down to their main body of text? I download a lot of things off of JSTOR for my studies and I like to print them 2 X 2 to a page, but to do so requires first getting rid of the extra page margins on each page (otherwise the text is printed far too small to read). If I could automate this, it would be great, but I can't seem to be able to do it with any of the programs I have (which includes Adobe Acrobat Professional 7.0). Is there anything out there which can do this? It seems like it would be a not-too-difficult feature to make, on the scale of things. I tried using the "Remove White Margins" setting on the "Crop Pages" screen in Acrobat but that does not seem to do anything at all with JSTOR files. --Fastfission 00:44, 16 October 2005 (UTC)

If I understand you well (wich I doubt), you should try to use Ghostgum GSview. It is a program that lets you view and print .pdf, .ps, .ps.gz files in the formats A3, A4, 11X7, B5, etc, and off course, user defined formats. Please, clarify your question. --User:Mdob | Talk 03:35, 16 October 2005 (UTC)

I think I clarified it as much as I could -- it's not a problem in creating PDFs, it is processing PDFs once I have them. In this instance, I download PDFs of articles from JSTOR, but they are often not suitable for printing the way I want to (saves paper, etc.) unless I spent about 5-10 minutes tinkering with each one of them doing some fairly formulaic things (cropping, mostly). My question was whether there was some way to automate this particular need, which is a pretty standard thing (automatic cropping, for instance, is a feature of many graphics programs). --Fastfission 18:57, 16 October 2005 (UTC)

Do you have Adobe Photoshop? You can program scripts in Photoshop (called "Actions") that can do a series of manipulations on all files in a directory. Photoshop can edit PDF's, but it will turn them into raster graphics first. I would google "photoshop actions" and read some of those results and see if this might work for you. --Quasipalm 03:40, 16 October 2005 (UTC)

I have photoshop, I hadn't thought about trying to use it for this. I'm not sure if it can do the auto-rotating I'm looking for (it might be able to do autocropping) but at least it's an avenue to look into, thanks. --Fastfission 18:57, 16 October 2005 (UTC)

The "Remove White Margins" function in the Crop Pages dialog in Acrobat should do exactly what you want as it eliminates all white space outside all visible data. The reason it does not work in this case is I believe JSTOR stores each page as a scanned image, not as PDF data, even though the file format is PDF. As such, Acrobat interprets the whole page as an image and therefore all visible data. If so, Photoshop Actions would definitely be the best idea here. You can download an AutoCrop action here: [2] and just add a step to the action to do the Auto Rotate. --Canley 03:36, 18 October 2005 (UTC)

How Electrons Stay In a Probability Field Around a Nucleus

How do electrons stay in their probability field without going anywhere? It can't involve strong nuclear forces (mostly inside the nucleus), weak nuclear forces (too long a distance) or gravity (too weak for the masses involved), so I can only assume that they are kept in check by exchanges of messanger photons. Is this correct?

electrons are keep binded to the nucleus by an electromagnetic potential, see Schrodinger's equation. The particle model of exchanging virtual photons is not used at all to explain atoms. See Hydrogen atom. --User:Mdob | Talk 02:25, 16 October 2005 (UTC).

Actually, being bound by an electromagnetic potential in ordinary quantum mechanics is equivalent to exchanging virtual photons in quantum field theory. The difference is that in regular QM the electric field is treated clasically while the electron is quantized; in QFT both are quantized (with quanta of the EM field being photons). Now, it's not very useful to use QFT to explain hydrogen atoms; so many virtual photons are exchanged that treating the EM field classically is just as good and much easier. -- SCZenz 09:29, 16 October 2005 (UTC)

Processes

What is the difference between multithreading and pipelining in a process?

Try our articles Thread (computer science) and Instruction pipeline.-gadfium 05:53, 16 October 2005 (UTC)

h5n1 virus

how do people get the deadly bird flu virus? i realize migrating birds have now carried it to europe from southeast asia where many people have died... but how do you get this particular flu? thanks, sherry

We have a good article on the virus, which pretty much answers your questions: H5N1 - Transmission and Infection ☢ Ҡieff | Talk 14:13, 16 October 2005 (UTC)

Fubini-Study metric from Euclidean metric

I have read that there is a natural way to induce the F-S metric on a projective space, can any helpful soul tell me what it is? Apparently there is a natural way to assign distance between lines passings through the origin, but what that might be escapes me. Thanks -Lethe

Could it be the (acute) angle between the two lines? —Keenan Pepper 16:53, 16 October 2005 (UTC)

Hmm... I had considered angle as a possibility before, but for some reason, it seemed too easy to be the right answer. But after your suggestion and some further thought, I can see for example that in RP1, if you add two lines in the plane by angle, then the slope of the third line (which is the inhomogeneous coordinate of the real one dimensional projective space) is given by

$m_{3}={\frac {m_{1}+m_{2}}{1+m_{1}m_{2}}}$

by the sum of tangents, which bears some similarity to the Fubini-Study metric. But of course that formula will only work for colinear lines, so there's still work to be done. -Lethe | Talk 19:55, 17 October 2005 (UTC)

LCD monitor's picture quality and sharpness

I recently bought a 15” LG LCD (TFT) monitor. The sharpness and quality of picture in the new TFT-LCD monitor is not as good as my previous monitor, which was a Samsung CRT 15” monitor. I asked about this to the dealer from whom I bought the monitor. He said that even though LCD (TFT) monitors cost more than CRT monitors, both sharpness and picture quality would be better in CRT than LCD (TFT). 1) Is it true? 2) If I should get sharpness and picture quality, what should I do? Is the product faulty?

The first thing I would check would be to make sure that your computer is outputting a picture that has the same resolution as your monitor. Due to the nature of LCD displays, they work best that way. For example, my PowerBook's display has a 1024x768 resolution, and when I have the computer's resolution set to 1024x768, the picture is as sharp as a tack. However, if I set the resolution down to 800x600 or 640x480 to play a game or something, the picture becomes more "fuzzy" because the display has to fake a resolution it wasn't built to display. So find out the native resolution of your new monitor, and make sure that your computer is set to output a picture with that resolution. In Mac OS X, click the Apple menu, select System Preferences, click on Displays, and click on the correct resolution in the Resolutions list. If you're using Windows, take your entire computer back to the shop and buy a Mac instead -- or try this. Garrett Albright 16:47, 16 October 2005 (UTC)

Also, using the DVI connector you can get a sharper image than with the VGA connector. --cesarb 01:10, 17 October 2005 (UTC)

The difference between digital DVI and analog properly configured VGA connection to an LCD screen is virtually un-noticable. Most users will be more than happy with the results that can be obtained from an LCD screen but many graphic design professionals still prefer to use CRT for their higher resolution, higher contrast and better colour reproduction. --Martyman-(talk) 03:22, 17 October 2005 (UTC)

Also, I'm not sure if this is still true, but there was the problem that the liquid crystals didn't change state fast enough for gamers. A fast changing image would therefore get blurred. But they're getting better in that respect and maybe they've already caught up with CRT's. DirkvdM 11:01, 17 October 2005 (UTC)

This was indeed a problem with fast-moving action games and sometimes even movies with fast motion, but, at least in this gamer's opinion, it's no longer a problem. My little PowerBook's screen can push pixels around without breaking a sweat. Garrett Albright 15:50, 17 October 2005 (UTC)

Electronic document format

I am choosing a format to make documents in. I am aware of XHTML, OpenDocument, Open eBook and DocBook. (Have I missed any important format?) On what basis can I choose one of these formats? —Masatran 17:49, 16 October 2005 (UTC)

There's also PostScript and GhostScript, as well as PDF and other proprietary formats. As for which format you should choose, what exactly is your target audience for these documents? How will they be reading them? Are you going to distribute the documents over the internet, or send them to a print shop, or both? How much money do you have to spend? These will make a difference in choosing which format to go with. Garrett Albright 19:14, 16 October 2005 (UTC)

I use HTML for two reasons. One is that you can you can easily edit the source, which gives you more flexibility if you have trouble getting the rendered text the way you want it. You can also do this with word processor files like .doc using a simple text editor, which doesn't interpret the source but just displays it. But that isn't designed for this, so it will probably be more cumersome and there certainly won't be as many manuals on how to do this on the Internet (or books for that matter). With html you can also use any simple text editor, but something more elaborate like Mozilla Composer (freeware and the only wysiwyg-like html editor I know of). The other reason is that this is the only format of which you can be pretty sure that everyone can read it, because all operating systems come with a browser (and have done so for at least ten years). This is not only true now, but will remain true for, well, ever, I suppose. Standards change or disapppear, but browsers will always be able to read html (I assume). And as the standard expansions like CSS, XHTML and XML get more widespread (which they pretty much are already) you can start using those too (though you can alsways for your own purposes). DirkvdM 11:14, 17 October 2005 (UTC)

Have you heard of Nvu? It's a fork of Composer which is also freeware and is quite capable as far as WYSIWIG HTML editors go. Give it a try. (I still prefer good ol' SubEthaEdit though.) Garrett Albright 15:35, 17 October 2005 (UTC)

By the way, I forgot, a disadvantage of html is that when you add a photo (or what else?) to a file it isn't integrated, but remians a separate file that can be referenced in different ways. So if you copy an html file, you need to make sure to also copy the files that go with it, and in the same relative or absolute location, or else you'll lose that bit. Is there a way around this? I find it a serious minus point of html. Does xml have a solution for this maybe? DirkvdM 10:12, 18 October 2005 (UTC)

In theory, there is. You could setup a webserver with an SQL server and PHP. The SQL server would then store the images (you'd have to insert them with an identifier), and a PHP script would be used to extract them and display them as images. That means you only have your HTML and the database to manage, or, if you also store the HTML in the database, only a handful of scripts and a database. --Pidgeot (t) (c) (e) 13:07, 18 October 2005 (UTC)

Theory that may be, but it's a horrible idea in practice. Retrieving data from a database like that would be slower and more resource intensive than just nabbing a file off a disk; it's an unnecessary and benefitless complication. Besides, it doesn't answer Dirk's original question as to whether images can be embedded into XML files. Answer: They could, but not in any way that would be meaningful to a standard web browser, AFAIK. Garrett Albright 11:55, 19 October 2005 (UTC)

MHTML is a MIME-based format to store HTML along with images, etc. as a single file. Another solution: OpenDocument makes a Zip archive of the files. —Masatran 16:24, 20 October 2005 (UTC)

SIGFUD

What is SIGFUD? Is it some kind of computer conference? — JIP | Talk 17:50, 16 October 2005 (UTC)

Hmm. I see you've posted an article on it. I don't know where you got the information about "SIGFUD" from, because it sounds quite made-up. Could you add a source to the article? RSpeer 18:11, 16 October 2005 (UTC)

The article looks like a joke to me, and Google returns nothing but the article and a few pages in Slavic. Someone please VfD this article… Wikipedia has kept me up past 4:00 AM again and I need to get to bed. Garrett Albright 19:21, 16 October 2005 (UTC)

User:JIP is a Wikipedia admin. So it seems strange that he/she should create the article and then ask on the Reference desk what it is. I will leave comments on their user talk page to sort this out. Majts 21:03, 16 October 2005 (UTC)

rsd

RSD redirects to Standard deviation. Is that what you're looking for? -- SCZenz 18:02, 16 October 2005 (UTC)

Or reflex sympathetic dystrophy? alteripse 20:17, 16 October 2005 (UTC)

I've created a dab page at RSD; if anybody knows any other things that use that TLA, feel free to add them in. TenOfAllTrades(talk) 14:55, 17 October 2005 (UTC)

Thyroid treatment

When is the best time during the day to give a pill to stimulate the thyroid for long-standing hypothyroidism --

• a. The first thing in the morning before any breakfast.
• b. An hour or a few minutes before the noon meal, on an empty stomach.
• c. With the breakfast meal.

There are no pills that stimulate the thyroid. Thyroid stimulating hormone (TSH) is a protein hormone taken as an injection with an effect that lasts about 1-2 days, but whether it stimulates the thyroid to make the right amount of thyroid hormone depends on whether

• a. the person's thyroid gland failed or
• b. their pituitary failed.

If your pituitary is making plenty of TSH and it was your thyroid that failed, injections of TSH won't do much good. On the other hand, if your pituitary failed, you could take an injection of TSH every couple of days. There are three drawbacks to using TSH as a treatment for hypothyroidism due to TSH deficiency:

• a. It's a shot instead of a pill and most people prefer pills.
• b. It is really expensive, like hundreds of dollars per injection, as compared to about 10 cents a pill for thyroxine.
• c. You would have to have many more blood tests to determine the right dose of the shot compared to using a pill.

So most doctors treat long-standing hypothyroidism not by trying to stimulate the thyroid gland to work again, but by suggesting the person take a daily pill of thyroxine to provide their needs. Like a vitamin, this can be taken any time of the day, has no side effects at the right dose, and is identical to your body's thyroxine. alteripse 20:16, 16 October 2005 (UTC)

Your answer is completely correct until the last sentence. Thyroxine supplement, as it was explained to me by a doctor (since I suffer from hypothyroidism) is a compound that 'binds' very easily to minerals as its processed by your body, and becomes completely ineffective to changing the free t4 level of the blood. It's best to take it on an empty stomach AND well before you plan on eating again, especially eating anything that might bind and render the medication ineffective. Most importantly, take it WELL away from any dietary supplements such as iron or multivitamins. If i have time I would like to qualify this with references, but I can't right now. --jeffmeden

You are correct that it is labeled from the pharmacy to take on an empty stomach because there are foods that bind it and reduce absorption, and there are a few published case reports of people in which the difference of absorption with and without meals was enough to change the dose requirement. Soy is perhaps the most notorious such food for young children. I probably should have agreed with that choice. However, despite this, many people who take it do not pay much attention to whether they take it with food and as long as the TSH levels are satisfactory are getting enough. Sometimes the adherence is enough better if they take it with breakfast every day than if they try to find a time apart from a meal that they get more of it. As far as vitamins and minerals specifically interfering with thyroxine absorption, I am skeptical that they make much difference. If you can cite a paper I would appreciate it. alteripse 20:43, 17 October 2005 (UTC)

After a little googling i found this page which has many references at the bottom, and explains a few noted absorbtion issues. The commonly accepted knowledge is that 'food in general' may slightly decrease levothyroxine absorbtion, as food would to any ingested supplement, considering your body is going after 50 to 150 /micrograms/ per dose, which is an astoundingly small amount. Compare it to a still tiny 80 milligram pain reliever, which is ~1000 times as much medication. --Jmeden2000 21:01, 17 October 2005 (UTC)

Thank you for the references, which appear to support your assertions for at least some people. Perhaps our only difference is how common and how large a magnitude effect this potential interference has. My experience is "uncommon" and "usually minimal or small effect", at least in young people. I will not dispute that it may be more than a trivial effect for some people. alteripse 03:03, 18 October 2005 (UTC)

water treatment

what is the difference between the water that enters a purification plant and the water that enters a sewage treatment plant? how are the water treatment processes different? 64.12.117.12 00:47, 17 October 2005 (UTC)brittany

See our articles on water purification and sewage treatment. Garrett Albright 03:08, 17 October 2005 (UTC)

Gravity and (substance)

As a sort of follow-up to the "gravity and water" question--are there other substances that would be OK to fall on? For example, a 1000-meter deep vat of feathers, or something of that nature? Meelar (talk) 03:33, 17 October 2005 (UTC)

Haha, yes I guess so. Anything that dissipates your kinetic energy slowly and during a long period of time would do. I suppose sinking on a 1000-meter deep vat of feathers would work in this case, but you'd sink quite a lot on it and probably die of asphyxiation before they could dig you out of there. :P ☢ Ҡieff | Talk 04:28, 17 October 2005 (UTC)

It's actually quite simple(in theory). Here's one way to look at it. There's a physical concept called momentum. Basically, it's mass*velocity. Velocity is essentially equivalent to speed(if you're going in a straight line). So you're momentum is mass*velocity. When you hit, your velocity drops to 0; so does your momentum. The change in velocity is called impulse. Impuse is equal to force* time. Hence, for a given impulse, the greater the force, the less time it takes for the change in momentum to complete. So, if you know your mass(say 40 kg) and the velocity on impact (say 4 m/s), you know momentum on impact(160 kg*m/s). That's the same value as the impulse, since you're going to 0. Then, figure out the maximum force your body human can take(say 1600 kg*m/(s^2) ). Divide impulse by force to get time(.1 s). So for that very contrived example, you need to find a material that will cause you to take .1 or more seconds to stop. Finding that stopping time for a given material is the hard part. :) Superm401 | Talk 06:11, 17 October 2005 (UTC)

In movies they use stacks of cardboard boxes. I'm not sure if they need to be stacked in a certain way, though. And in one Due South episode (I believe the last one) Fraser says it's ok to jump out of an airplane over a field of thick snow because the snow will break their fall. Which it did, but they had to climb out of the holes their bodies created (which of course showed their silhouettes in cartoon fashion) . Then again, that's Due South, so don't try this at home (assuming it's big enough to fly an airplane in in the first place, but I've made that silly joke before). DirkvdM 12:27, 17 October 2005 (UTC)

Historically, landing in snowbanks is safer than *not* landing in snowbanks... but you need to know it's a snowbank, not just 3" of snow over a rock ledge! Jumping into (snowy?) pine forests is good - the branches aren't thick enough to kill you hitting them, but the multiple layerings means that your fall will be broken repeatedly. Shimgray | talk | 20:50, 17 October 2005 (UTC)

I vaguely recall seeing TV footage of some guy setting the new world altitude record for jumping off an aircraft without a parachute. I think the landing spot consisted of a stack of gigantic really soft foam mattresses. I might be misremembering, though. Ilmari Karonen 20:59, 24 October 2005 (UTC)

Database

what is database? what is table? what is tuple? what is relational DB?

What is homework? What is missing indefinite article? What is database article containing? --Robert Merkel 04:14, 17 October 2005 (UTC)

Why are there so many famines in Africa?

I'm not sure if this question would fit under the "Science" heading, but I figure since it has to do with agriculture it's the best place to start. It seems that every few months there is a food security crisis in some African nation, with the most recent one being in Swaziland. I'd like to know why there are so many famines in Africa even in proportion to other less developed areas. Impaciente 03:27, 17 October 2005 (UTC)

Because not all developing countries are anything like equal in living standards. GDP per capita in Iran, India or even Bangladesh, are far in excess of Africa's poorest countries. As to why this is the case, there's a variety of reasons. Some parts of Africa have an extremely variable climate and marginal soils, unlike some of the poor tropical countries which are actually very fertile. Then there's AIDS, which is having a disproportionate impact in Africa and destroying the agricultural workforce.

But the biggest issue by far is the corruption and malevolence that infests African governments at all levels. A lot of African famine has more to do with people being forced off their land due to conflicts of one kind of another than variability in agricultural production. As to the reasons for this, well, there's plenty of blame to go around, and a fair proportion can be assigned to colonialism. --Robert Merkel 04:30, 17 October 2005 (UTC)

I'm going to argue for an alternative theory about African famines, one closer to the one put forward by Amartya Sen. I would first argue that GDP comparisons are ineffective both at the high end and low end of the scale - that it's hard to assert the US is really much wealthier than western Europe, and it's hard to claim that Bangladesh is wealthier than many African countries. Its GDP per capita is lower than Sudan's. Instead, I would look at the fragility of infrastructure and the ability and willingness of the state to mobilise resources against famine.

Sen points out that most famines are very local - most often the state will have large areas that are not suffering from famine at all - and that market forces can easily shift some surplus production into the starving area so long as the starving people have the money to buy it. The state can readily provide enough money to starving people - money costs almost nothing to create. In India, the government responds to famine with New Deal type programmes that put money into local pockets.

In order for this to work, three conditions have to exist:

1. The economy must be monetised. Its transactions must primarily involve trading goods and services for money, not direct barter.
2. The material and organisational infrastructure to move food in significant quantities must be in place.
3. The state must have the credit to be able to spend money freely in the affected areas, and it must have the willingness to do so in response to famine conditions.

I think that much of Africa is missing at least one of these conditions, while in Asia only North Korea - which lacks the first condition - faces any real risk of famine. --Diderot 06:33, 17 October 2005 (UTC)

I directly thought of two old examples that I remembered because the causes were surprising. In Biafra there was a famine in the early 70's I believe, which made me think it was a very poor region. Only later did I find out that it was actually a very oil-rich region of Nigeria. All that wealth (at least what was left after Shell oil took their share) was spread over the whole (populous) country. So the Biafrans came up with the idea of separating from Nigeria so they could keep it all to themselves. Of course this led to war and famine. So in stead of getting rich the ended up being starved to death. The other example was in the Sahel not much later. The reason that was given for that famine was that western medicine had greatly reduced infant mortality. But the tradition was to have many kids (because of the high infant mortality rate), so the population exploded during a time of good harvests. Then, when a bad harvest came, which previously wouldn't have been a problem, it led to mass starvation.

About the GDP issues that Diderot mentions (this has nothing to do with the question). When I first heard of some of the wages in some countries that sounded ridiculous - how could those people survive? But when I went to Africa I noticed two things. Firstly, prices for most goods were as low as the wages (only western goodies like tv's were about the same price (as well as the beer, to my horror)). Secondly, a lot of people use little or no money because in rural (jungle) areas people grow their own food and barter. Which can also take the shape of 'I now help you build your house for free, so in ten years time you can help mine'. Such an 'economy' could not work in the individualised western world. See also GDP#Controversies. DirkvdM 13:02, 17 October 2005 (UTC)

Actually, you'd be surprised at how much American poverty involves barter and subsistence. Rural poverty in particular - not just in America but even in parts of Europe - often involves a combination of land ownership so that costs are lower and subsistence gardening. But, a shocking amount off real income among the urban poor consists of barter and quasi-barter arrangements. Exchanges of services like babysitting, home and car repair, school help, discounted or free goods like old cars and TVs... this sort of lifestyle is not so strange even in America and makes the difference between life and death in some cases. Aboriginal Canadians are also closely tied to semi-subsistence and barter economies that simply aren't rich enough to draw the attention of the tax man even when they aren't protected by treaty, and it wouldn't surprise me to find the same behaviours on American reservations too. The Amish in particular have institutionalised a system of community debts and payments. Just as markets existed in the midst of "really existing socialism" alongside and as a part of the command economy, a significant non-monetary economy persists even in the most developed states. --Diderot 17:07, 17 October 2005 (UTC)

Greed causes famine. We in the west will give to the poor only when the poor are thrust into our living rooms.People think only of themselves.A few weeks ago mob greed saw a run on the petrol pumps even though there wasn't a shortage. There is never enough petrol to fill every tank in one day but everyone was thinking only of me,me,me. A government that is always mindful of greed amongest its voters will put the third world poor bottom of the list. None of us are going to vote for a government which would give the third world a fair price for it's goods because we would end up paying more. If the good land used to provide us with cheap tea,coffee,tobacco or sugar was given over to grow food for local people much of the hunger in the world would stop. Next time you have a coffee think of the family, mother,father,and kids who spend the day, all day, everyday, just managing to pick enough beans to feed themselves. We are all part of the system which causes famine. --Eye 19:31, 17 October 2005 (UTC)

Don't just think about them. There's a capitalist way you can do something about this, by buying Fairtrade labelling products, which ensure that more money goes to the farmers in stead of to middlemen. This started with coffee but expanded to other products. But you also mention governments buying the coffee and such. They don't, private companies do (in most parts of the world). But they could, and that would constitute a socialist solution, which shouldn't cause the price to rise, as you suggest. The government could do exactly what those fairtrade companies are doing, without the market having to wait until some private company applies it to some product. DirkvdM 07:40, 18 October 2005 (UTC)

Personally I am somewhat skeptical about this coffee v. foods theory. The only possible scenario that this theory holds true, in my opinion, looks like this (exaggerated to show my point):

There's a poor country with lots of poor farmers. One man with gun took the land from many poor defenseless farmers and hired only a few people to grow coffee with machines. This Mr. Gun builds a castle and saves his coffee money in a Swiss bank account without spending it locally. People are now without land to feed themselves. Only a few coffee workers are not starving but their lives really suck.

I don't think land use is much of an issue here. If without Mr. Gun, local coffee farmers and workers will always use the earned money to buy their own food. If you pay peanuts for their coffee, they can grow maize rather than buying nothing for themselves with your peanuts. Mr. Gun is the problem.

However, there are also many people without land and jobs. With the introduction of modern medicine, many people otherwise could have been dead are now having a chance to grow up. This is actually a curse to them. Because their people are still having too many babies for their own good. And thir societies lack the means to create more jobs. If 200 are living on a land used to support only 100, some of them would always suffer.

Famines and plagues are the norm on earth. People used to be living like animals all over the world just a couple of hundred years ago. If without the culture and science to support this greatly increased population, all of us could face famine some day. Personally, I suggest that we have as few babies as possible. The ecosystem could be on the verge of a total breakdown if the consumption continues. -- Toytoy 09:14, 18 October 2005 (UTC)

You don't need a gun for this. Money is much more effective. An uneven distribution of money (which is the norm in the world) has the same effect. Only those without it might ressort to using weapons if they're desperate enough. Which is why a 'socilaised' capitalist society (such as in the Netherlands) is a guarantee for the rich to safely remain much richer than the rest. As long as the 'poor' don't starve they won't revolt. Socialism killed the the Communist revolution (which is not to say that that's a bad thing). DirkvdM 10:04, 18 October 2005 (UTC)

I know of some cases where collective farming is the culprit. Socialized Agriculture resulted in farmers being directed to grow cash crops instead of food crops. The cash crops were sold and the money was used to purchase arms to export revolution in neighboring countries, or went into the bank account of corrupt government officials, or both. This was because the farmer was not allowed to decide what crops to grow, but the government official made these decisions.

But in the developed world, the market tells farmers to grow cash crops instead of food crops to buy gasoline. I don't see intrinsically how the two cases lead to different outcomes in case of crop failure. --Diderot 15:58, 18 October 2005 (UTC)

• Whatever you do, don't even consider the possibility that they brought it on themselves, no, no, not people taking responsibility for their own actions, how dare we sacntion such a wacky idea--WwJd 04:29, 20 October 2005 (UTC)

• Please ask yourself, WwJd, would jesus blame the victims of famine for their own misfortune? --Quasipalm 01:38, 23 October 2005 (UTC)

Setting up internet website through a broadband connection

My laptop has Debian Linux Testing with the Apache HTTP Server installed. It has a 256 kbps BSNL broadband internet connection through PPPoE. How can I set up an internet website with this? The webpages are ready; how can a domain name be mapped to my computer? The IP address appears to be 59.92.33.82; is this fixed or will it change everytime I re-connect to the internet? How can I keep it fixed? —Masatran 04:51, 17 October 2005 (UTC)

You need to talk to your Internet Service Provider about getting a permanent IP address. If you don't do this, then the IP address may change; probably not every time you connect to the internet, but perhaps every few months.

You need to register a URL with the appropriate body; which body depends on whether you want a .com, a .net etc address, or a country-specific URL such as .bz. Your ISP may be able to help with this, but they may charge you more than if you do it yourself.

Alternatives to getting a permanent IP address are to have a process on your computer regularly check for changes to your IP address and update the mapping from the URL to the IP when it does, or get hosting from a commercial site (or your ISP) for your website.-gadfium 05:31, 17 October 2005 (UTC)

Your ISP (Bharat Sanchar Nigam Limited?) may try to charge you extra for a static IP. If you try to host a site with a dynamic one, you also may be violating your TOS. Hosting a site can be really annoying without a static IP, though it's possible. As for the domain, you can register one yourself for fairly cheap(<$10). Just search on "domain registration". Price shop a little bit before you buy. Superm401 | Talk 06:01, 17 October 2005 (UTC)

If you really want to do this from your home computer and can't get a static IP, you can look into Dynamic DNS, which I use for my own website. You might also consider whether it might be easier to be hosted elsewhere; these days you can get "virtual private servers" (as far as you're concerned, you've got your own server box with root on it, but many of these are hosted on the one physical box) for less than 10 USD per month. It might be cheaper in India. This also means you don't have to have your computer on all the time, which can easily outweigh the costs of the hosting service. --Robert Merkel 13:20, 17 October 2005 (UTC)

Physics-Kinematics

A roller coaster, of mass 100kg, is 10m above the ground at its atarting point, A. It moves down a straight, steep slope of 50m in length to a point X.

What is the displacement? Is it 10m or 50m?

This is my exam question. It asked me to find the velocity of the roller coaster at X, if a frictional force of 20N is acting on it.

How do I find it? My answer was 13.4 m/s (3.s.f). Am I right?

Do your own homework - if you need help with a specific part or concept of your homework, feel free to ask, but please do not post entire homework questions and expect us to give you the answers. -- Ec5618 15:54, 17 October 2005 (UTC)

• We have articles on displacement, kinematics and acceleration, which together should be of great help to you. - Mgm|^(talk) 22:11, 17 October 2005 (UTC)

As far as I can see, without known the incline of the slope, this question is unswerable. Perhaps you misread the question? -Lethe | Talk 01:15, 18 October 2005 (UTC)

Aaaaarg! here is the full answer (using the principle of conservation of mechanical energy):

         R  <--------Roller coaster in t(0), Potential energy:
        /|                                    10*100*10
       / |                                      Cinetic energy: 
50m   /  | 10m                                   0
     /   |
    R----+
    ^  (48,something)
    |
   Roller coaster at t(1)
 Potential energy=0   
 Cinetic energy=10,000 - 20 = 9980
 
    m*v2                 100*v2
  E=---        ->   9980=-----  -> v2=199,6 -> v=14,13
     2                    2

So, the speed ~14.13, and the displacemente is 50m. Note: probably your teacher made an error, the problem doesn't make sense with 20N, but it does with 200N. --User:Mdob | Talk 23:12, 18 October 2005 (UTC)

Thats not right, frictional force is acting alone the plane, so the displacement is 50m, that is the distance the coaster travels, and all anong that way friction tends to stop it with a constant force of 20N. Force is N=kgm/sec^2 energy is Kgm^2/sec^2. The energy spent is going down is mgh=100*9.81*10=9810J the energy spent on friction is Fd=20*50=1000J The final energy is going to be all Kenetic, and is 9810J-1000J=8810J this is 1/2*m*v^2 Solving for v v^2=2E/m=2*8810/100=176.2 We get displacement of 50m v=~13.3m/s I enjoy kinematics. Dominick ^(ŤαĿĶ) 22:32, 19 October 2005 (UTC)

Yeah! Dammit! 20 newtons for 20 joules. damm (and fatal) distraction. --User:Mdob | Talk 23:48, 20 October 2005 (UTC)

Note also that the problem is not about kinematics, but about dynamics (the tree parts of Mechanics are kinematics, dynamics, statics).

Where is Athens?

Athens, Greece or Athens, Georgia? Or maybe you are looking for Atlantis? --Screwball23 14:23, 17 October 2005 (UTC)

All the Athenses are at Athens (disambiguation). TenOfAllTrades(talk) 14:35, 17 October 2005 (UTC)

rockets

why have different countries pursued rocket development?

Generally, rockets have two uses: one, for missiles such as the MIM-104 Patriot missile, or two, for sending stuff into space, such as satellites and even people. Of course, development-wise, there could be overlap, so technology originally developed to propel space shuttles could be applied to missiles and vice versa. (A third use for rockets is fireworks, but generally nation-states aren't too concerned about those.) Garrett Albright 15:43, 17 October 2005 (UTC)

For world war and world peace. smurrayinchester^{(User), (Talk)} 16:02, 17 October 2005 (UTC)

It started with the V-series of rockets developed by Werner von Braun for Nazi Germany. For war purposes. Then von Braun was taken to the US where he wanted to develop space rockets, but again he had to build war rockets. And in the USSR Sergey Korolyov faced the same problem, but was more successful in convincing his superiors that space rockets would also serve the cold war effort (spying being one use). But mainly, I believe, the USSR went into space for promotional purposes. This gave them a headstart, after which the US needed a full decade to catch up with them. DirkvdM 09:12, 18 October 2005 (UTC)

chemistry

Is it true that ions are always larger than atoms of any element regardless fo wheter they are anions or cations?

• Not usually. It depends on how you define "size", but my databook says that carbon, for instance, has a covalent radius of 77 pm, but C⁴⁺ has an ionic radius of only 16 pm and C^4- an ionic radius of 260 pm. For most elements it appears cations are smaller, as you'd expect. --Bob Mellish 17:24, 17 October 2005 (UTC)
• Anions are always larger, cations are usually smaller (it can get confusing for transition metals). Physchim62 13:36, 18 October 2005 (UTC)

Why is the brain located in the head?

Don't answer. Its a trick question....ahaaaa!

This is actually an interesting question. Our bilaterally symmetrical ancestors had need for a lot of sensory and motor nerves in the front of the body and connections between them because that was the part that met food and enemies first. Ever since then, the ganglia at the front have been increasing in size and complexity and importance, partly because that need has never gone away. We still meet the world with our faces and have more need for instant response to things which impinge on the nerves in that area. -- WormRunner | Talk 19:53, 17 October 2005 (UTC)

Not all brains are located in the head of an animal, but I forgot which specific animals deviate. It may also depend on what you call a head. Basically, the brain is a concentration of nerves and I believe some animals have concentrations elsewhere as well. Don't worms have a 'node' in each section? DirkvdM 09:16, 18 October 2005 (UTC)

If by "worm" you mean annelid, then yes there is a node in each section, but these ganglia are not the same as the brain, even in earthworms. That said, the only place where the "brains in the head" statement really applies is the annelid/arthropod group and vertebrates. It certainly doesn't apply to molluscs and echinoderms. I suspect the poster was only thinking of human heads. -- WormRunner | Talk 16:19, 19 October 2005 (UTC)

See also octopus. If you have a strong stomach you might also be interested in Mike the Headless Chicken. Shantavira 08:07, 19 October 2005 (UTC)

• Obviously thousands of years of random mutations all added up to form a fully functional human head right out of thin air, nothing far fetched about that--WwJd 04:27, 20 October 2005 (UTC)

• • • Well, in fact that's exactly what did happen, so it is by definition not far-fetched. However, believing a giant mythical man created us in a magical garden 4,000 years ago and then created women from a piece of rib-cage; it makes perfect sense! --Quasipalm 01:36, 23 October 2005 (UTC)

• • As WormRunner mentions, for animals that move primarily in one direction, those that have their sensory organs at the "front" will obviously have a survival advantage, and having the neuron ganglia near the sensory organs would also provide an advantage, both in terms of speed and in terms of efficiency (rather than having nerves carry the signal back to the brain, then back to the organs). WwJd, I don't understand your comment; yes, millenia of mutations resulted in what is now the human head. But I cannot reconcile that statement with the comment about arising right out of thin air. It is true that creationists believe that, and yes, many people find it farfetched, but they may believe what they wish. — Knowledge Seeker দ 05:46, 20 October 2005 (UTC)
  • Yeah! Let's replace it with God, who has the exact same problem! Brilliant! — ceejayoz ^{★ .com} 12:58, 20 October 2005 (UTC)

The pay and college education of a volcanologist...

I was wondering... on average how much a year does a volcanologist get paid? Also, how long do you typically have to go to college for if you are going to work for the USGS?

Thank you. April

• If I remember correctly this question has been answered earlier, please check further up the page and the archives. If the answer isn't there, try one of the other reference desks. - Mgm|^(talk) 22:11, 17 October 2005 (UTC)

April asked the question earlier, but we didn't give her an answer on the pay. April, follow the link in my last sentence for answers about how long you need to go to college for.

The pay varies according to experience. I can't answer for the USGS, but I tried two Google searches: vulcanologist salary and volcanologist salary. From these, it appears that pay ranges between US$30,000 and US$100,000. If you look at these searches yourself, please check what the currency being referred to is - not all positions are in US dollars.

The USGS does give a table of salaries here, but I can't find anything which explains what grade range a volcanologist may be in. This site will only help if someone can find an explanation of grades for scientists.-gadfium 03:03, 18 October 2005 (UTC)

best way to display a dynamic binary tree on the web

I want to display a tree on the web. I did a similar project many years ago when I was a student where I displayed a binary tree in Java. But I'd rather something more native to web browsers. I have a LAMP (apache with php and mysql database on gnu/linux) set up, and I want to dynamically display portions of data stored as a tree (not necessarily binary). What's the best way to render this? I thought maybe CSS. Does CSS have the ability to layout things precisely enough to make a tree? I've never used CSS, so I'm not sure what it's capable of. So can it like, have an outlined box with a picture, some text and hyperlinks in it, and place it according to coordinates that I would calculate, then draw lines connecting various such boxes in a tree shape? The coordinates and slopes and placements of lines would all be calculated in php. So what do you think? thanks -Lethe | Talk 21:01, 17 October 2005 (UTC)

I think the best solution would be either to nest the results within <h1>..</h1> <h2>..</h2> tags (if you dont have that many branches) or nesting using list elements <ul><li> more o less like the following code:

  <ul>
    <li class="level1">Item 1</li>
    <li class="level1">Item 2</li>
    <ul>
      <li class="level2">Sub-Item 2</li>
      <li class="level2">Sub.Item 2</li>
    </ul>
    <li class="level1">Item 3</li>
  </ul>

yields:

• Item 1
• Item 2
• Sub-Item 2
• Sub.Item 2
• Item 3

Modifiyng the base css allows you to costumize indentation and stuff as much as you want, it is something that can be done easily using LAMP too... --Threner 21:41, 17 October 2005 (UTC)

Ummm.... but that's not a tree, that's a list....? thanks though. -01:04, 18 October 2005 (UTC)

It is a nested list, which means it is no different from a tree, you have nodes and leaves... you only have to change the definition of the li element to display any kind of format you like in the bullet... check this example, it is done using css http://css.maxdesign.com.au/listamatic2/vertical14.htm --Threner 03:49, 18 October 2005 (UTC)

I believe the original poster it trying to create diagrams like this: Image:6n-graf.png. If you want, you could use CSS to position the boxes: just put each of them in a div, and give it a style attribute like so:

<div style="position: absolute; top: 123px, left: 456px; border: 1px solid black;">graph item</div>

Unfortunately, to the best of my knowledge CSS has no way of drawing diagonal lines, circles or other advanced shapes. Since you already have PHP set up, you might want to try using the GD library (http://us2.php.net/gd) to construct the diagram as an image. Another alternative would be SVG, but that currently requires a browser plugin. --David Wahler (talk) 15:09, 18 October 2005 (UTC)

What caused the big bang?

What caused the big bang?

Flatulence. --Diderot 21:09, 17 October 2005 (UTC)

Have you read our article on the Big Bang and related subjects (particularly Timeline of the Universe)? Of particular (perhaps philosophical) note is the question of whether causality has any meaning prior to the theorized beginning of the universe and its associated physical laws. — Lomn | Talk / RfC 21:24, 17 October 2005 (UTC)

The big bang is a theory which is based on the theory that the universe is expanding which is based on the observation that the light coming from distance stars leans towards the red end of the spectrum the cause of which is based on the theory that light acts as a wave and the wave is being stretched making the light appear reddish. If the universe is expanding then it must have all come from some central point and been blown out in a Big Bang? Hmmmm….. Plenty of room there for debate… --Eye 21:32, 17 October 2005 (UTC)

It's a remarkably successful model of cosmology. It explains all sorts of very different observations about the universe, from the cosmic microwave background to the amounts of different elements. There are no other models that do the same.

If you don't like gravitational redshifting, then you don't like General relativity, and that's an even more well-grounded theory.

Other than that, debate all you want. ;)-- SCZenz 21:55, 17 October 2005 (UTC)

. It's not that I don't like the theory it's just that popular culture often presents it as fact.--Eye 18:23, 18 October 2005 (UTC)

It's the best theory we have at the moment (and it's pretty darn good). Popular culture often presents established theories as fact; for example, the laws of thermodynamics. Nothing special about this one, scientifically. --Ashenai (talk) 18:27, 18 October 2005 (UTC)

The big-bang has been the bedrock of cosmology for 35 years now; the nobel-prize winning discovery of cosmic background radiation was more-or-less the last nail in the coffin. At this point, you'd be hard pressed to find a non-crackpot who has an alternative to it (in fact, someone who disagrees with the Big-bang is a crackpot almost by defintion). →Raul654 01:06, 19 October 2005 (UTC)

Calm down guys and gals I was only suggesting that if something is accepted as fact when it can't be totally proven then we close the door on other possibilities. Don't be a flat earthling. At this moment in time all the doors should be open. --Eye 20:29, 19 October 2005 (UTC)

The possibilities that are plausible should be open. There's only one, at the moment. Come up with another one and I'll be the first to reconsider.. ;) -- SCZenz 20:40, 19 October 2005 (UTC)

• Gee, completly unobservable, unprovable, untestable, seems scientific to me--WwJd 04:25, 20 October 2005 (UTC)
  • Actually, it is observable, in a sense (see cosmic microwave background radiation), and it is quite testable as well. The big bang theory makes a number of predictions, about the intensity of radiation, the rate at which the galaxies recede from each other, the relative amounts of the first elements to form, the age of the universe, and so on. As Raul mentioned above, discovering (accidentally; they weren't even searching for it) the background radiation that the theory predicted was what really sealed the fate of the other models. Of course, nothing is science is provable, so being unprovable is certainly scientfic. At any time, we may make a new discovery which the big bang theory does not explain well, and instead come up with a new model that better explains it; more likely, it won't be enough to invalidate the big bang theory, but will refine it instead. That's how science works. The door is always open to other possibilities; it's just that right now no theory explains the origin of the universe nearly as well as the big bang theory does. — Knowledge Seeker দ 05:40, 20 October 2005 (UTC)

Ah, I sense a subtelty here. As an aside, think of all the theories in the world, and rank them in terms of "absolute truthfulness", on a scale of 0 to 10. 10 being completely true, and 0 being completely false. No scientific theory could ever score a perfect 10, although scientific theories can asymototically approach this value. This is a very healthy thing :-) --HappyCamper 16:08, 22 October 2005 (UTC)

Lunar Question

Is it possible to age the craters on the Moon. Apart from the fact that the younger ones over lap the older ones is there a way of looking at one of the craters and determining its age?--Eye 21:18, 17 October 2005 (UTC)

No, moon craters don't suffer erosion, since there's no atmosphere or water in there. But you can date them using radioistope dating --User:Mdob | Talk 00:04, 18 October 2005 (UTC)

It's not erosion, but I found something that talks about space weathering. [3] "Part of what makes a moon crater look "fresh" is the appearance of a bluish tinge to the surface. This bluish tinge indicates lunar soil that is relatively untouched by a process called "space weathering," which reddens the soil. Another indicator of a fresh crater is that it reflects distinctly more light than the surrounding area." Also see our Geology of the Moon#Geologic history article which states, "The Apollo 17 mission landed in an area in which the material coming from the Tycho crater, which has a diameter of 85 km, had been distributed; the study of these rocks helped come to the conclusion that this crater had formed 100 million years ago. The surface has also experienced space weathering due to high energy particles and micrometeorites. This process causes the ray systems produced by impacts to darken until it matches the albedo of the surrounding surface." Here's a link from NASA about space weathering: [4], someone should start a stub. --Quasipalm 01:00, 18 October 2005 (UTC)

Gentic melding

I have seen many references to hybridisation and cross breeding but true melding. What I mean is pick apart two animal structures and adding them together, getting rid of any duplicate parts. The specific idea I had was a wolf-tiger an animal that contain traits of both animals. This method would not really on the normal methods of half the genetic structure being taken from each parent but the merging of two complete DNA strands. Sorry if I’v repeated mysel (or anyone else) here.

--82.30.242.131 22:20, 17 October 2005 (UTC)

• Whats the question?--inks^T 00:55, 18 October 2005 (UTC)

We don't follow your distinction and suspect it is based on some erroneous assumptions or misunderstanding of basic gene function. Hybridization and crossbreeding, if the offspring are fertile, matches your definition of "melding". What do you imagine is the difference between merging DNA and hybridization to a single genome? alteripse 02:57, 18 October 2005 (UTC)

What is the Geiger-Nuttal Law?

What is the Geiger-Nuttal Law?

Facial Hair Growth

Does the growth of male facial hair increase by shaving it? Thanks. -Haon 00:40, 18 October 2005 (UTC)

No. From [5]: "Shaving does not make the hair shaft thicker, darker, or grow faster or slower. However, the short hair shaft may be more noticeable as it grows out because it has a blunt tip instead of the normal tapered tip. " Other sources: Mayo Clinic Snopes "Beardguy" on AOL --Quasipalm 00:51, 18 October 2005 (UTC)

LEVERS

hey, are tweezers a first, second, or third class lever?

Take a look at lever which explains the three classes with examples.-gadfium 02:38, 18 October 2005 (UTC)

While we are on the subject, has anyone encountered this class system for levers outside of a school textbook? Is it used in the real word anywhere?--Commander Keane 14:02, 18 October 2005 (UTC)

And what about state capitals, sentence diagrams, long division, times tables, gym, batik and civics. Useless, useless...Brian Schlosser42 17:30, 18 October 2005 (UTC)

You don't use your times tables?--Commander Keane 17:18, 22 October 2005 (UTC)

Barometer

How does a barometer work?

There are many types of barometers. look in the article and see which specific kind you're looking for. --Borbrav 05:11, 18 October 2005 (UTC)

alligators and crocodiles

Which one, the alligator or crocodile, opens it's mouth by raising it's upper jaw and which one opens it's mouth by lowering its bottom jaw? --68.33.167.172 03:34, 18 October 2005 (UTC)

• Based purely on the photograph on the Crocodile article, I would say the crocodile raises its upper jaw. I can't quite tell from the photograph on Alligator, but it looks like it could open it's mouth by moving the lower jaw. --Canley 03:45, 18 October 2005 (UTC)
  • I was under the impression that everything has the upper jaw as part of it's skull and that the only way anything could open it's mouth is through the articulation of the bottom jaw. --Martyman-(talk) 04:26, 18 October 2005 (UTC)

How to seperate chlorophyll a & b,and carotenoids before doing the Absorption Spectrum of Chlorophyll a

I would like to know the details of the process about seperating chlorophyll a & b,and carotenoids before doing the Absorption Spectrum of Chlorophyll a

Paper chromatography works. first Google HTML hit ("enjoy" the webpage background). I you can read a PDF file, go here. --JWSchmidt 19:41, 18 October 2005 (UTC)

Drugs and Alcohol

My teacher keeps telling us that alcohol is the only drug that affects every organ of the body because it flows through the bloodstream. But what about heroin when you inject it? What about vicodin and other drugs? Dont they also affect every organ?

Come on. If you eat a candy, the sugar will enter your bloodstream (simplified) and every living cell in you body will eventually nurished by the sugar. If you breath, oxygen will do the same thing. If you drink water ...

Sugar, oxygen and water aren't drugs. DirkvdM 09:57, 18 October 2005 (UTC)

Tell that to the principal in Missouri who suspended a child for giving another child a drug: a glucose tablet. alteripse 21:02, 18 October 2005 (UTC)

I don't know what are the receptors of alcohol in human cells. I also don't know if all cells, tissues and organs are responsive to alcohol. I'd like to know the answer. -- Toytoy 09:28, 18 October 2005 (UTC)

That something flows through the blood doesn't necessarily mean it affects everything. Heroin, for example, is much like endorfins (no article on that? I do spell it right, don't I?), so the body accepts it as something natural and uses it where it is normally used, which is in the brain. But then heroin is a substance the body recognises and this is not the only way something can affect a bodily part. DirkvdM 09:57, 18 October 2005 (UTC)

endorphin. -- Toytoy 11:11, 18 October 2005 (UTC)

As with most drugs of abuse, alcohol affects primarily the brain and the liver. Physchim62 13:41, 18 October 2005 (UTC)

Alcohol is highly soluble in water, whereas the other drugs are not. This means it can pass through tissues. When Alcohol

is consumed some of it actually penetrates the tounge and enters the bloodstream that way. Other drugs do not do that, at least to that extent. It also does not need to be digested to enter the blodstream and can be used as food, sort of. There is a story that certian types of diabetics can take in alcohol in an emergency to keep them alive until help arrives. I do not know how true that story is, though. Read it years ago in readers digest.

Not true. alteripse 21:03, 18 October 2005 (UTC)

Read about receptors. Most drugs have actions on specific organs because their recptor-mediated actions are generated only in certain parts of the body. Alcohol has effects on cells that are independent of a specific receptor, allowing it to have effects on all cells. The chemical nature of alcohol that gives it the ability to penetrate to all tissues (see above) is also important. --JWSchmidt 14:01, 18 October 2005 (UTC)

what are the dangers of salvia?

enviroment and its relation with geography

You can find a lot about the environment here at Wikipedia. Environments are frequently affected by geography; for instance, where the geography is below sea level, the environment is usually wet. For a more complete answer, please ask a more complete question. — Lomn | Talk / RfC 13:53, 18 October 2005 (UTC)

QF 25 pounder Short Mark 1 (australia)

Please, does anyone know when the QF 25 pounder was first manufactured in Australia, and by whom? -- Chris

• Our article on the 25 pounder does not contain the information directly, but it does link to LemaireSoft, which refers to a diferent designation: 8.76cm FK 280. A quick google search yields several links, among which this one, which details the history of the weapon. -- Ec5618 11:02, 18 October 2005 (UTC)

Sales of commonplace automobiles

I would like to know the order of magnitude of the yearly sales of some modern average, commonplace model of automobile (with references if possible). David.Monniaux 12:32, 18 October 2005 (UTC)

Within the context of your question, please define the terms "modern", "average", and "commonplace". Dismas|^(talk) 13:16, 18 October 2005 (UTC)

Commonplace = a kind of car commonly bought today (ex: Peugeot 206 in France), i.e. not luxury cars

Average = a market segment that ordinary people buy (i.e. not luxury cars, not sports car)

Modern = produced within the 5 last years David.Monniaux 13:53, 18 October 2005 (UTC)

Automotive Intelligence has compiled a fair amount of information relating to annual sales for various manufacturers. If you want national figures, most nations have an association of automotive importers and manufacturers who compile such things. --Robert Merkel 13:39, 19 October 2005 (UTC)

What is the 'Vero cell line'?

Hello, what is the Vero cell line? Regards, Stuart.

Please, search first - it's quicker. Search Wikipedia using the box to the left. A web search could help too.

A google search yielded this file which explains that The Vero cell line (a single cell line) was derived from the kidney of a normal, adult, African green monkey (Cercopithecus). In addition to its use as a vaccine cell substrate, this cell line has been used extensively for virus replication studies and plaque assays.

The rationale behind the use of Vero cells rather than primary monkey kidney cells is that these cells can be banked and well characterized, which avoids the issues of lot-by- Iot variability and adventitious agent contamination of primary cultures freshly initiated for each production run from the kidneys of wild-caught monkeys. In addition, the continued use of animals is problematic from ethical and economic viewpoints. Numerous investigational products are being produced or have been proposed to be produced in Vero cells. -- Ec5618 17:58, 18 October 2005 (UTC)

Elementary particles

What are WIMP's and MACHO's? Have any been observed so far? Chosen One 17:34, 18 October 2005 (UTC)

Please search first - it's quicker. Search Wikipedia using the box to the left. A web search could help too. -- Ec5618 17:49, 18 October 2005 (UTC)

Hey, you don't have to shout, I can understand normal English, well, thank you. Chosen One 19:12, 18 October 2005 (UTC)

Don't post while intoxicated is my advice. - Cobra Ky (talk, contribs) 04:45, 20 October 2005 (UTC)

I'm sorry, but I wasn't shouting, I was copying the exact rule you should have followed, as it is written at the top of this page. Had you read those rules, you would not have had to ask your question, and your linguistic abilities would not have been doubted. -- Ec5618 20:08, 18 October 2005 (UTC)

Try WIMP and MACHO. — Laura Scudder | Talk 17:45, 18 October 2005 (UTC)

Laptop and digital camera woes

Okay, since the Peanut Gallery answered my spoiled hamburger question so well, hopefully I can get some equally good advice about my laptop...I have an old (2001 era) Gateway laptop as my backup computer. The fan has died, and for a while it worked OK, so I took it to my brother, a semi-pro electronics wiz to repair. However, as the fan is very hard to come by, he can't fix it. Now, it overheats and goes into safe mode in about a minute. Next week I am going on vacation, and will be taking my Fuji S3100 camera with me. I have one 256 Mb xD memory card, and the idea was that I would use the computer for a few miuntes a day to dump the photos. But now, I can't even do that, as it wont stay on long enough to copy the files. So, I had an idea: What if I keep the laptop in the refrigerator to keep it cold? I know thatthis is not usually a good idea, and that condensation is going to be a problem, but frankly I want to take a lot of pictures more than I want to keep the dying laptop. So, will this work as a way to keep it running for a few more days? I won't need it more than 15 minutes a day, for 7 days. Any ideas? Brian Schlosser42 19:25, 18 October 2005 (UTC)

The fridge might help, but the problem is more a lack of airflow (where inside-case temps might pass 150°F) rather than ambient temperature. I think you'd have better luck, and far less risk of a short-circuit, fire, or generally dead laptop, if you created some ductwork with paper and tape connecting a desk fan to the fan vents on the computer. It certainly wouldn't be any more cumbersome to work with than typing in the crisper. — Lomn | Talk / RfC 19:31, 18 October 2005 (UTC)

I have actually used a small external fan to cool my laptop when the internal fan died and it worked reasonably well as long as I wasn't doing anything too processor-intensive. Your mileage may vary. -- WormRunner | Talk 21:29, 18 October 2005 (UTC)

Ok, no 'fridge. I'm going to buy a desk fan to ventilate it, as this seems to be the consensus. Thanks for the advice, folks. Brian Schlosser42 13:26, 19 October 2005 (UTC)

Some Ballistics

A friend and I have had an ongoing dicussion regarding what happens when someone fires a bullet straight up. As the physic laws state, in a vacuum the speed of the bullet, which is 300 m/s using a common handgun), as it comes down would be the same as when it left the chamber (Parabolic shot). So it would go fast enough to kill someone. However, I believe that because of the small mass and friction with the air the bullet would slow down so much that it is mostly harmless. Am I right? --Threner 21:13, 18 October 2005 (UTC)

Do not try this one at home. The terminal velocity–the bullet's maximum speed as it falls–depends on its mass and shape. It is definitely possible for a falling bullet to cause injury; such mishaps are a staple at U.S. hospitals around the Fourth of July and New Year's Eve. These injuries are sometimes fatal; whether the victim dies (or even suffers serious injury) probably is affected by the size (caliber) of the bullet, how thick his skull is, and a substantial measure of luck.

Don't look up, either. By doing so you expose the soft tissue and thinner bones of the face, and possibly the major blood vessels of the neck. TenOfAllTrades(talk) 21:31, 18 October 2005 (UTC)

Any idea of the falling speed? i the article on Terminal Velocity states that a easy way to calculate the speed would be to tie the bullet to a vehicle using a thin string. When the bullet reaches 45 degrees, the speed of the vehicle is the terminal velocity. I really want to try this at home to calculate how fast does the bullet go while falling. I wonder if a bullet at 100km/h could kill someone. Still, at least I know that the bullet slows down enough for it to be not necessarily mortal --Threner 21:38, 18 October 2005 (UTC)

• • • I've read (somewhere, I can't find it now), that somebody measure the terminal velocity of a bullet (I don't know what calibre) as ~90 m s^-1. That would be 200 mph or so. --Bob Mellish 23:26, 18 October 2005 (UTC)

If you search Google for 'bullet terminal velocity', you get a bunch of handy references, including (in part) [6]:

"Different bullet types behave in different ways. A .22LR bullet reaches a maximum altitude of 1179 metres and a terminal velocity of either 60 metres per second or 43 metres per second depending upon whether the bullet falls base first or tumbles. A .44 magnum bullet will reach an altitude of 1377 metres and a terminal velocity of 76 metres per second falling base first. A .30-06 bullet will reach an altitude of 3080 metres with a terminal velocity of 99 metres per second. The total flight time for the .22LR is between 30 and 36 seconds, while for the 30-06, it is about 58 seconds. The velocities of the bullets as they leave the rifle muzzle are much higher than their falling velocities. A .22LR has a muzzle velocity of 383 metres per second and the .30-06 has a muzzle velocity of 823 metres per second.

According to tests undertaken by Browning at the beginning of the century and recently by L .C. Haag, the bullet velocity required for skin penetration is between 45 and 60 metres per second which is within the velocity range of falling bullets. Of course, skin penetration is not required in order to cause serious or fatal injury and any responsible person will never fire bullets into the air in this manner."

See also [7]:

"B. N. Mattoo (Journal of Forensic Sciences, 1984) has proposed an equation relating mass and bullet diameter that seems to do a better job. Experiments on cadavers and such have shown, for example, that a .38 caliber revolver bullet will perforate the skin and lodge in the underlying tissue at 191 feet per second and that triple-ought buckshot will do so at 213 feet per second.

Mattoo's equation predicts that Hatcher's .30 caliber bullet, which has a small diameter in relation to its weight, will perforate the skin at only 124 feet per second. It's easy to believe that such a bullet falling at 300 feet per second could kill you, especially if it struck you in the head."

Hope that helps. There are a lot of other sources out there that reach essentially the same conclusion—getting hit by a bullet as it falls at terminal velocity is likely to be painful and is potentially fatal. Larger-caliber bullets are generally more dangerous than smaller. TenOfAllTrades(talk) 04:11, 19 October 2005 (UTC)

Mythbusters did a sort of similar experiment where they investigated whether a penny thrown from the Empire state building would penetrate a skull. They found that there was NO WAY a penny could ever even pierce skin at its terminal velocity (they shot themselves with their experiment-guns to prove it). The terminal velocity for a bullet would ofcourse be alot higher, but from watching that experiment, i doubt that it would pierce a cranium. But don't try it at home :P gkhan 00:16, 20 October 2005 (UTC)

A Penny has a lower terminal velocity than a lead round. Falling lead has injured people, however, I have seen stray rounds from a rifle range bounce harmlessly off of people. A large round would hurt from a ways up; 300m/s sounds like a pretty slow and large caliber. Dominick ^(ŤαĿĶ) 19:08, 20 October 2005 (UTC)

My brother once dropped an orange from the tower of Pisa (oh, how very original...). It created a rather deep hole in the ground, so he was lucky there no-one passed by there at the moment (not to mention the other person of course). DirkvdM 14:35, 24 October 2005 (UTC)

Domain name transfer

What's the simplest way to transfer a domain name? I noticed that someone had a domain name that he wasn't using, emailed him, and he offered it to me for free so long as there weren't any tranfer fees. However, he probably wouldn't feel comfortable just giving me his username and password. What's the easiest way?

Thanks, — Asbestos | Talk (RFC) 23:46, 18 October 2005 (UTC)

There's not really any transfer fee. In fact, you can start a transfer registration at Dotster(and others) for less than a regular registration(per year). So, it will be less than 9.00 for the entire year after transfer, and you don't have to pay a fee just for transferring. Superm401 | Talk 03:16, 19 October 2005 (UTC)

Thanks. Also, I currently have a domain name registered under GoDaddy, and am thinking of using them for webhosting as well. With most hosting packages, can you share out the space among different domain names? I noticed Ace-host.net seemed to have one domain/one-hosting space only. — Asbestos | Talk (RFC) 04:33, 19 October 2005 (UTC)

I don't know about GoDaddy, but I use DreamHost and am hosting seven domains with one account, so it seems to vary by company. I'm very happy with DreamHost's services by the way, and would recommend them to anyone. Use this link to check 'em out, and if you sign up, I'll get a referrer bonus. :) Garrett Albright 11:38, 19 October 2005 (UTC)

Ink Markers

Can you please tell me what keeps the ink inside markers? Thank You. Susan Thomas ---01:16, 19 October 2005 (UTC)

You mean keeping it from running out? The little wick on the end keeps the small amount of liquid in the case. It actually is flowing all the time, by evaporation through the wick. When you have the cap on, there is very little evaporation. When you press it to paper, clothing, skin or other items to be marked, capillary action allows the liquid to flow. If there is nothing to flow to, not much comes out. Dominick ^(ŤαĿĶ) 02:42, 19 October 2005 (UTC)

Thanks for the answer...my 9 year old granddaughter thanks you also..

Polynomial bound attainment

Yes, this is homework. But it's only part of the homework, and homework we are encouraged to discuss. And homework whose deadline will almost certainly pass by the time you read this. And yes, me (I, actually) and several others have thought long and hard about this to no avail.

Let P: R^n -> R be a multi-variable polynomial that is bounded below. Does P attain its infimum?

The single variable case can be proven reasonably easily, but the method does not seem to extend to more variables. --Fangz 01:54, 19 October 2005 (UTC)

Try thinking of the question in this way: Let's take P. Can the bounds on P be of the form [a, b]? What about (a, b)? What about {a, b]? What about [a, b}? What about (-ifty, +ifty), (-ifty, b], (-ifty, b), (-a, +ifty), [-a, +ifty)? If you can think of examples/counterexamples, then essentially you would have answered the question. --HappyCamper 03:17, 19 October 2005 (UTC)

Spaces in fixed-width fonts in Microsoft Office Word 2003

When I use MS Office Word 2003 and type in a fixed-width font like Courier, the spaces between the words can get thinner, giving the appearance of right-hand justification even when the paragraph is marked for being flush-left, not right-hand justified. Is there any way to turn that off? It's very annoying. Thanks! --Angr/_{tɔk tə mi} 08:59, 19 October 2005 (UTC)

Correct me if I'm wrong, but doesn't "flush left" mean that it should adapt the spacing between words to make all lines appear equally long? Use a plain old left justification instead, that'll do the trick. --Pidgeot (t) (c) (e) 14:44, 19 October 2005 (UTC)

For me, "flush left" is the same as left justification. At any rate, it's not supposed to be fiddling with the spaces between words, and it is. --Angr/_{tɔk tə mi} 18:14, 19 October 2005 (UTC)

Life on other planets.

If I am correct, the conditions for life to develop on a planet are as follows

1. Distance from the parent Star. The planet in question has to be in more or less the same orbit as Earth is from our Sun.
2. The Star itself has to be similar to our Sun. A bigger sun does not last long enough and a smaller one will not be radiant enough for life to develop.
3. Presence of water. Water is known to be a pre-cursor for life.
4. Presence of Carbon, hydrogen and Nitrogen which form complex molecules.

The Question is, if the precursors of life are the same, shouldn't Life on other planets also take the same form that we have taken? Won't other planets also evolve bacteria, fungi, plants, animals and should I dare say Intelligent beings who may look so much like us?
-WarrKay 03:31, 19-Oct-2005(IST)

• Not entirely, the distance of a planet can differ, provided the star's radiance fits the position of the planet. Also, the conditions for Planetary habitability are based on what we know. It's quite possible there's life that fits other conditions, but our current scientific knowledge can't prove anything about that either way. - 131.211.50.198 09:56, 19 October 2005 (UTC)

Nobody knows, but life on earth is so diverse it suggests life could be very diverse elsewhere. Among the most intelligent animals on earth are dolphins, dogs, and octopi, which don't look anything like us. Shantavira 09:59, 19 October 2005 (UTC)

• Re intelligent dolphins, see Hitchhiker's Guide to the Galaxy. ;) Don Diego 10:02, 19 October 2005 (UTC)

A lot of things in this universe depend on chance. It was only because of our solar system's unique arrangement that life was able to develop here. If life on other planets were to develop in exactly the same way, i.e. following our evolutionary process, the planets would more or less have to be arranged in the same way as ours, and then the timeline has to be the same, etc. Life could evolve also without these precursors. National Geographic produced a series called Extraterrestrial, wherein scientists speculated about the evolution of life on other planets, for example on a gas giant's moon, surrounding a red dwarf, etc. The parameters were changng constantly, and the show itself was very interesting. Don Diego 10:01, 19 October 2005 (UTC)

One of the important points of evolution is that it is random. Microbes may well be very similar to our Earth ones, but as life evolves further, more differences would emerge. For example, eyes are considered to have started as a random mutation which caused a light sensitive patch of cells. If early beings did not get this mutation, then the entire natural history of the planet would be very different. smurrayinchester^{(User), (Talk)} 10:03, 19 October 2005 (UTC)

Although light sensitive cells, which eventually lead to the evolution of eyes, are so advantagious that when they do randomly develop they tend to stick around. Which is why the eye has seemingly evolved independently many times. See convergent evolution --Majts 02:53, 20 October 2005 (UTC)

Life can exist in a much broader range of environments than we're usually taught in secondary school biology; see extremophile. And those are just organisms evolved on earth. The evolution of life on Earth itself was not terribly predictable and involved a great deal of chance- there's a book about this by Stephen Jay Gould called Full House.--Pharos 10:13, 19 October 2005 (UTC)

Organisms could even develop resistance to UV-rays if they were situated on a planet orbiting a dwarf star. But then again, it depends on the heavenly lottery, where life is going to evolve. Intelligent life, on the other hand, could already possibly exist, although either they are to shy to communicate with us, have tried to remove all traces of their existence so as not to be bothered by stubborn Earthlings, or have not yet developed the technology to communicate with other alien beings. If intelligent life other than our own races existed, I'd dare say that they don't want (or need) visitors from beyond. Don Diego 10:18, 19 October 2005 (UTC)

No, it won't take the same form, for the same reasons the dolphins can't mate with sharks. Even on earth, the role of chance in evolution is overwhelming, and even where organisms of different origins have evolved similar traits to fit similar ecological niches, they are still very radically different. Alien organisms should be even more different. I think this is one of the stronger arguments against the existence of intelligent alien life - I think that it is as wrong to imagine aliens being intelligent in the way humans are as it is to imagine sharks to act like dolphins, and I have yet to see a convincing definition of intelligence that doesn't boil down too "seems to be like humans". --Diderot 10:53, 19 October 2005 (UTC)

I would say dolphins are rather similar to sharks (at least the smaller sharks that eat fish). They have similar skin and fins, no hair or fur or feathers, no visible ears, etc. These similarities are remarkable considering how different the evolutionary paths are that led to those creatures. Another example of parallel evolution is bees and hummingbirds, which both independently devloped the ability to hover in flight in order to feed off flowers. StuRat 23:08, 21 October 2005 (UTC)

I assume that we are talking about life as we know it....Capitan. :-) --Eye 22:15, 19 October 2005 (UTC)

There are some interesting speculations about additional conditions for life at the Fermi paradox article. --JWSchmidt 00:08, 20 October 2005 (UTC)

Who says life can't be silicon-based? --65.188.159.140 02:57, 20 October 2005 (UTC)

• Of course, even most mainstream scientists will admit that there's no evidence of any life sustaining planets, anywhere else in the galaxy, and that man is most likely a unique creation--WwJd 04:20, 20 October 2005 (UTC)

• Keep in mind, "life" is only a word; a literal metaphor used to express an idea. This would require us to define what life is. Some suggest fire is alive. It is born in a sense, and it dies in a sense. Fire consumes, and it also reproduces. In this case, if we are to suppose that our definition of life must in some way or another involve DNA, then yes, there are very specific requirements (carbon, oxygen, nitrogen, and hydrogen, as well as a number of other spacial requirements), but as suggested above, why can life not be silicon based? Or an as yet to be discovered form? What I'm getting too is that with this perspective in mind, the universe itself can be seen as alive, and we (being carbon-based lifeforms) are only one of a potentially countless array of possible configurations. - Cobra Ky (talk, contribs) 04:55, 20 October 2005 (UTC)

Might I suggest an article to open your minds?

• Alternative biochemistry- Cobra Ky (talk, contribs) 04:36, 20 October 2005 (UTC)

The idea that everything is alive sits well with me even if it is only in the spritual sense. --Eye 22:06, 20 October 2005 (UTC)

Brain hyperactivity

Throughout my entire life, I had a problem with "thinking". I always thought way too much about things, all sorts. I can't control it at all, and in several occasions I got headaches and sick because of it. It's physically PAINFUL sometimes (I get tense and my throat, face, neck and guts hurt). I've tried learning relaxation techniques and all, seen psychologists, and even got to a few doctors who offered me some medication (fluoxetine). It didn't work. Recently I had an issue with a friend, partially because of this. I, of course, am feeling terrible about it. The problem is, this led to a major impulse in this thinking pace, and I can barely sleep now. I'm hardly hungry (but I got more thirsty for some reason). And this all scares me. I'm beginning to think there's something neurological behind this. So I set an appointment with a neurologist. I'm not sure if this is the best thing to do, but can't be any harm, eh?

My question is this: are there any sort of neurological conditions that cause this sort of problems? If so, what sort of medical solutions can be taken? If not, what could I possibly do, I've ran out of ideas here.

Attention-deficit hyperactivity disorder, Obsessive-compulsive disorder, and Amphetamine use come to mind. (I'm not a doctor -- you should wait to see your neurologist before jumping to any conclusions.) --Quasipalm 14:28, 19 October 2005 (UTC)

OCD, perhaps, but the rest? I don't think so. I don't have problems with ADHD, I can focus on things and everything, I just can't control thinking about everything else while I'm at it at the same time. This is what bothers me.

Have you considered meditation? Also I can't help wondering whether you need to get more exercise. Your diet might also be a factor. Shantavira 19:10, 19 October 2005 (UTC)

Yes I have, along with the relaxation and all... Tried it 15 minutes/day for about a month, and I just couldn't stop these "streams". Also, this triggered some sort of double personality, so I started arguing with myself, inside my head, while I was with this. It's like some other part of me was trying to disturb me. Now, excercise and diet seem more likely to be an issue. I'm very sedentary and my diet is poor (i'm underweight and my diet is not very rich, indeed)...

Proper diet and exercise might well be the cure. Even if they aren't, getting healthier can't exactly hurt, can it ? I particularly think the balance of electrolytes is critical. I have noticed I get muscle spasms when I haven't eaten well, maybe it affects your brain. If, and only if, proper diet and exercise fail to fix the problem, should you consider going to psychoactive meds. They could mess you up, so don't risk it unless you've used up all other options. StuRat 22:57, 21 October 2005 (UTC)

The symptoms you describe could means lots of things, including a little bit too much anxiety and self-analysis. None of us have any business diagnosing you with anything definite. However, I will offer guidance to the right kind of doctor. Your symptoms undoubtedly fall on the mind side of the old cartesian mind:brain divide. Whether you need reassurance and insight, constructive suggestions, or diagnosis and treatment, you will get more help, more sympathy for the symptoms, and a more experienced perspective from a mind doctor than a brain doctor. I promise I am saving you a step. Good luck. alteripse 23:09, 19 October 2005 (UTC)

Yes, but I've seen psychologists and they all said the same thing: that I had some self-esteem issue so I was constantly judging myself, and that I'm too anxious with things, so I judge them too often. They sent me to this other guy who gave me the fluoxetine, which, like I have stated, didn't help. BTW, I'm 19.

I would be careful. I was diagnosed with OCD and put on medication. Nothing worked. I had 4 different kinds over 4 years. By then I was a wreck. Finally I found out I did not have OCD. It has taken me years to recover. If the problem is just thinking, then that is not really a problem. If the problem is thinking about the same things over and over without any resolution, that is an anxiety disorder. You are probably very smart and like to think about things, like quantum physics. Arguing with yourself might just be a very pronounced way of resolving inner issues, trying to make decisions. Alteripse is right, though, when saying none of us has any business diagnosing you by 'remote control' this way. Find a good counsellor and get some help, it may be you just have an active imagination. Top priority is to find a counsellor you trust.

I have a similar problem, though nowhere near as serious. I just can't get to sleep because I'm constantly thinking of things. A 'solution' that has worked for me for 25 years is to smoke some marijuana before sleeping. Just a bit works wonders. A big advantage is that if it doesn't help it won't hurt any either. A potential major problem is that it can land you in prison in many countries (I have the good fortune to live in the Netherlands). Although even in the US it's accepted as a legal drug these days, I believe. You'd just need a doctor to prescribe it to you. DirkvdM 15:07, 24 October 2005 (UTC)

Define gravitation

Please remember to search before asking questions; see our article on gravitation.

Take a look at gravitation. — Laura Scudder | Talk 16:36, 19 October 2005 (UTC)

It's also a huuuuge book by John Wheeler, but Laura's link will probably be more helpful. -- SCZenz 16:39, 19 October 2005 (UTC)

Basic binary sum circuit

I had to create a basic binary sum circuit for my computing class, where three single-digit inputs would be summed to obtain two outputs, one for each digit of the sum (e.g.: if I had 1, 1 and 1 as input, I would get 1 and 1 as output; if I had 1, 1 and 0 I would get 0 and 1, and so on). I can do the first digit no problem - (A xor b) xor C - but I'm having some trouble doing the second digit. So far I have succeded in summing the first two inputs - A and B - but I don't know how to sum the third. Any help? :) Sorry if this explaination is somewhat incoherent, but English is not my native language -- Whitetigah 16:39, 19 October 2005 (UTC)

Try looking at the adder article. --cesarb 16:49, 19 October 2005 (UTC)

Thank you, that was exactly what I was looking for :) -- Whitetigah 17:41, 19 October 2005 (UTC)

astrophysics

why are almost all planets in the solar system coplanar i.e all their orbits lie on a single plane?is it specific only tothe solar system or is it found in other planetery systems?

They are not exactly coplanar. You may read the Protoplanetary disc article for some insight. There is also the issue of outer planets acting like large vaccuums, and removing smaller planetoids, and other bodies with odd orbits. Dominick ^(ŤαĿĶ) 17:13, 19 October 2005 (UTC)

You might be interested in the discussion on this question elsewhere at the Ref Desk. Note that Pluto's radical inclination is widely believed to result from Pluto's post-creation capture as opposed to the co-formation of the other planets. 199.209.144.218 17:28, 19 October 2005 (UTC)

Sand bags

Considering the relatively higher permeability of sand compared to clay, shouldn't we ideally be using "clay bags" rather than "sand bags" in a flood?--Commander Keane 17:46, 19 October 2005 (UTC)

• My guess, which is only my guess, is that clay is a lot harder to move around than sand. --jpgordon∇∆∇∆ 18:02, 19 October 2005 (UTC)

Sand can be removed later, clay sets and sits in one place. Sandbags collect garbage from the floodwaters and do a surprizingly good job at damming a flood, from my personal FL experience. (Turn Wilma turn!) Dominick ^(ŤαĿĶ) 18:08, 19 October 2005 (UTC)

That's the great thing about sandbags: even if some water gets through the sand it's clean, so you just have water damage, rather than mud/gunk everywhere on top of water damage. I'd also think that the fact that sandbags naturally reshape themselves to fit their neighbors is a big advantage over clay. — Laura Scudder | Talk 18:35, 19 October 2005 (UTC)

Sandbags are particularly useful as secondary supports. An unsupported concrete wall can easily be pushed over in a flood, due to the pressure differential between water on one side and air on the other. If sandbags are piled up against the air side, that will substantially eliminate the pressure differential and prevent collapse. StuRat 22:46, 21 October 2005 (UTC)

A few questions about Hybrid vehicles like Prius

I have a few questions about hybrid vehicles like Toyota Prius. What I want to know is- 1) How much more hybrid vehicles like Prius cost (in %) more than gasoline powered vehicles with similar power and capacity? 2) How many times mileage does Prius or other hybrid vehicles give compared to similar gasoline vehicles? 3) Should we charge the battery that runs the car similar to electric cars? 4) Are all hybrid vehicles automatic geared?

Many of your questions can be answered at hybrid vehicle, or by surfing the web sites of car manufacturers. But here's some quick and dirty answers:

1. According to Toyota's web site, the Prius starts at US$21,275, whereas the Matrix, which seems to be of a similar size, starts at $15,110. So it's about 35% more expensive. But I'd bet you'd make up the cost in gas savings fairly quickly.
2. Toyota's site says the Matrix gets up to 30 city MPG, whereas the Matrix gets 60 city MPG. Of course, numbers straight from the company like this are always wishful thinking…
3. No. The battery is actually charged by the gas engine.
4. That one I'm not sure of.

Garrett Albright 18:51, 19 October 2005 (UTC)

RE: #3 -- Some people have actually hacked their cars to be able to plug them in overnight at home. See here. They reported that the Prius was able "to reach between 100 and 180 MPG in a typical commute" after the change. So, why don't hybrid cars ship with the ability to plug-in? Reportedly, because car companies were so afraid that people would think that cars that plug in would be annoying or weak, they didn't even build them with the option. Dumb, eh?

RE: #4 -- The Honda Insight has a manual / hybrid version.

--Quasipalm 19:06, 19 October 2005 (UTC)

The matrix is significantly larger than the Prius, the Prius is more similar in size to the Echo. A better comparison would be the Honda Civic ($14,650) vs. the Honda Civic Hybrid ($21,850), that's a 50% difference in price and averages 15mpg better. That means at 10000 miles/year and gas at $3/gal, The Civic would use 285 gallons of gas a year and the Hybrid would use 200 gallons of gas a year. That means you save a whopping $255 a year, which means you would have to own the hybrid for over 28 YEARS for you to come out ahead. Despite the manufacturer's marketting, Hybrids are still nowhere CLOSE to economically feasible. Even with gas at $5 a gallon, it would take almost 17 years, with gas at an absurd $10/gallon, it would take 8 and a half years. -Drdisque 22:21, 19 October 2005 (UTC)

Here's a great site, Garrett, fueleconomy.gov. --Quasipalm 23:15, 19 October 2005 (UTC)

Avian influenza

Is VIRA 38 snake oil or actually capable of reducing the risk of catching avian influenza should it begin to spread amongst humans? Also, is Tamiflu available anywhere via mail-order without a prescription? I'm not freaking out or anything, but Science Friday freaked me out a little last week. (Perhaps it's a good time to re-read The Stand ;-) --Quasipalm 18:56, 19 October 2005 (UTC)

I'm having trouble finding published research on "VIRA 38". As far as I know, the neuraminidase inhibitors such as Tamiflu have only been tested in short-term experiments. It is not clear to me that they are the solution to a flu pandemic. The idea that the world should stock pile these drugs in order to limit a pandemic seems to be a good way for a few drug companies to make a lot of money. It may be that the money would be better spent on ways to limit exposure of humans to the avian flu virus and development of vaccines. --JWSchmidt 23:53, 19 October 2005 (UTC)

A vaccine cannot be developed until the virus mutates into a form that can cause the pandemic. There is a delay of 4 - 6 month before enough vaccine can be produced. So the idea is, that antivirals will reduce the death toll in the meantime. Theresa Knott (a tenth stroke) 23:57, 19 October 2005 (UTC)

A human vaccine for the avian flu virus has already been reported ("AVIAN INFLUENZA: 'Pandemic Vaccine' Appears to Protect Only at High Doses" by Martin Enserink was in Science, Vol 309, Issue 5737, 996 , 12 August 2005 doi:10.1126/science.309.5737.996b). If actions (such as vaccination) were taken to protect against infection of humans by existing avian flu virus, then there would be a reduced chance of a mutant form evolving that would easily transfer between humans. There can be some protection from antibodies to a type of flu (like H5N1), even if the antibodies are made against a different variant of the type. If humans were vaccinated against the existing H5N1 type bird flu, there would be some protective antibodies that would cross-react with new mutant strains. I'm not saying that the neuraminidase inhibitors are useless, but I'm not sure that they are the best way to throw money at the problem, particularly if it just turns into a matter of those few who can afford the inhibitors getting them via mail-order. --JWSchmidt 00:33, 20 October 2005 (UTC)

Pulseless Electrical Activity PEA (EMD)

Hello, I hope you can help with this enquiry, I am currently on a medical course and have just failed a practical assesment. I was following the protocol as I understood it in that I shocked my PVT patient four times until their rhythm changed. What I saw was a sinus rhythm and checked the carotid pulse and was told that there was a weak palpable pulse. I interprited this as sinus rhythm and gave AV for one minute and re analysed patient. On completion I was told that the patient had been in PEA and should have commenced CPR. Am I way off the mark or can you as was explained to me by the assessor a palpable carotid pulse in PEA?

Many thanks Alastair Palmer --62.189.84.170 18:57, 19 October 2005 (UTC)

A Google yielded our Pulse article, the baseline Emergency Medicine guideline to palpate for carotid pulse for 10 or more seconds as a preliminary for CPR, and some additional guidelines for performing immediate surgery. It looks like the technique is fundamental for physicians. But a further Google using the exact wording on your question also indicates this is a pre-terminal condition with a 5% survival rate, so it is unclear to me why CPR for PEA (EMD) is more than a stopgap; a 3rd Google shows that the CPR responder should also be requesting Advanced Cardiac Life Support (ALCS) at the same time. Thanks for posting the question. But the Google hits make me wonder whether the symptom lack of carotid pulse=>CPR is consistent with weak palpable pulse. What did the assessor mean by this? Ancheta Wis 10:31, 21 October 2005 (UTC)

Infinity

Many years ago I remember my maths teacher saying that mathematicians didnt use infinity in equations. Something to do with things not adding up. I was never interested in maths but that has always stuck in my head. Is this true? If it is true how then does science deal with infinity when the language of science is maths and infinity in terms of the universe is ..well .a distinct possibility.--Eye 22:12, 19 October 2005 (UTC)

You can't use infinity as some form of quantity, because when you try and do tricky things with it, things break down. Sure, inf + inf = inf, 2*inf = inf, but what is inf/inf? (Suppose inf/inf = a, then inf = a inf. You can choose any such a and the equation will still work). There are other cases like this.

However, infinity can be a useful symbolism. If you want to express the sum 1/2+1/4+1/8+..., you can write it as

$\sum _{i=1}^{\infty }{1 \over 2^{i}}$

but really, this is the same as saying

$\lim _{n\rightarrow \infty }\sum _{i=1}^{n}{1 \over 2^{i}}$

where the "lim" means the limit as you let n get larger and larger.

So infinity is more like a concept than a quantity. Lots seem to get entranced by the idea of infinity, so you should get a large response here... Dysprosia 22:35, 19 October 2005 (UTC)

(Added after edit-conflict so might be parroting Dysprosia a bit).

The thing with infinity is that it really makes no sense. Take for instance the classical example of divison by zero. Lets try dividing 5 by zero:

${\frac {5}{0}}=\infty$

Ok, so far, so good. Well, that must mean.....

${\frac {5}{\infty }}=0$

Sure, sure, ok, good.....

${\frac {5*\infty }{\infty }}=0*\infty$

Hmm, where are you going????

$5=\infty *0$

What???? Infinity times zero equals 5!!! Cool!! Anyway, the point is, when you treat infinity like a normal number (ie you put it in formulas and subject it too normal algebraic operations like cancelling out factors from a divison), ridiculus stuff happens. When math has to deal with infinity (and infinitismals), such as in calculus we replace them with limits. A limit is basically a number that goes "very, very close" to a certain point (such as infinity or zero). For instance, to find the derivative of the function x^2 (if you don't know what a derivative is, don't worry, it doesn't really matter) you have to simplify this equation:

${\frac {x^{2}-(x+h)^{2}}{h}}$

Where h is a number that is an infinitismal (ie an "infinitly small number", a number as small as possible). Normally, this would break the division by zero-rule, but if we impose limits we can work with it.

$\lim _{h\to 0^{+}}{\frac {x^{2}-(x+h)^{2}}{h}}$

$\lim _{h\to 0^{+}}{\frac {x^{2}-(x^{2}+2hx+h^{2})}{h}}$

$\lim _{h\to 0^{+}}{\frac {2hx-h^{2}}{h}}$

$\lim _{h\to 0^{+}}{2x-h}$

Now, since h is so tiny that it really doesn't change the result anymore (since it's basically 0), we can safely remove it and the limit and get the answer, 2x. This is a bit (alot) simplified since you are a non-mathematician (so am I btw, I'm a serious dilettante), but that's the gist of it. gkhan 22:54, 19 October 2005 (UTC)

Mathematicians definitely do use infinity, although for reasons the above posters mention, you must use care, or you'll end up in trouble. There are in fact several different numbers which could be called infinity. There is the infinity in the extended real line, which satsifies a bunch of things like infinity + any number = infinity. The expression infinity*0 is left undefined (no one claims that infinity*0=5). Other infinities include omega and aleph nought, and many more. -Lethe | Talk 01:06, 20 October 2005 (UTC)

Of course any discussion of infinity (you have at least skimmed that article right?) would be lacking without a mention of cardinality of infinity. That is something that blows most peoples minds when they first learn of it because they are used to the conventional wisdom of infinity being the biggest thing out there. How could there possibly be different sizes of infinity? Well at least in set theory there is. - Taxman ^Talk 18:17, 20 October 2005 (UTC)

I think you people are deliberately trying to confuse me. :-) --Eye 20:14, 20 October 2005 (UTC)

If $1/\infty =0$ then one might assume that the infinity being referred to is countable. However, if one accepts the existence of countable infinity, then by set theory (see Cantor's diagonal argument), one must also accept the existence of uncountable infinity. If the reciprocal of countable infinity is zero, then surely the reciprocal of uncountable infinity is also zero? Of course. But then what is the reciprocal of zero? Is it countable or uncountable? It cannot be both, because if 1/0 is equal to both infinities, then the two infinites are equal to each other, which they are not, by definition. So paradoxes such as these blow up in one's face, and one must conclude that infinity is somewhat beyond ordinary grasp.

It depends on what field of numbers one is dealing with. The field of real numbers does not include infinity even though its cardinality is uncountable infinity. So when one asks "how many real numbers are there?" the answer is not a real number. Real numbers are good enough for practical purposes: infinities being dealt with as limits. However, it is possible to define other mathematical structures which include things which are called "infinities". For arithmetic, see surreal numbers. For geometry, see projective geometry.

Physics is based on the ability to take measurements of physical quantities, such as mass, distance, and time. When an experimental physicist makes a measurement, the instrument which makes the measurement is finite, and the number resulting from that measurement is finite. Physical theories are confirmed by being tied down to experiment (see empiricism) and physical experiments always give finite answers. Physics deals with infinities being getting rid of them, by hook or by crook: see regularization and renormalization.

Mathematics, on the other hand, is rationalistic and not empirical. Mathematical structures are tested by self-consistency: if it is not self-consistent, it does not exist. Each mathematical structure is self-contained and independent of other structures, so Euclidean geometry and Riemannian geometry each have their own separate existences, even though they would contradict each other. (Likewise, the theory of infinity has two branches, one which accepts the continuum hypothesis, another which rejects it: but each branch capable of being self-consistent.) Moreover, mathematical structures do not have physical existence. The number five does not physically exist. One might have five finger's on one's hand, but the five fingers are not the number five. One might draw a red number 5 on a paper, but that five is not the concept of number five. The symbol $\infty$ for infinity is not itself infinite. The symbols which mathematicians manipulate on paper are all finite. Infinites are known only indirectly, through logical inference, and inhabit a non-physical realm. So when one says "There are a countable infinity of natural numbers", those numbers do not really exist physically. Besides, if mathematics only dealt with infinities, it would be impractical and rather useless and mathematicians would not gain their bread, whose quantity is finite, positive, and non-zero, which they eat regularly in order to obtain a finite, positive, non-zero amount of energy (see pragmatism). On the other hand, mathematics does have a corner of its realm permanently reserved for infinities: as Hilbert said: "No one can drive us from the heaven which Cantor created for us." —Anonymous, 20 October 2005

Computer science and math skills

I'd like to know just how skilled one would have to be at mathematics in order to go into the field of computer science. After reading some articles on the subject here on Wikpedia (which I could barely understand, if at all) it seems like a fascinating field. Impaciente 01:09, 20 October 2005 (UTC)

Computer science is broken into several branches, including computer engineering/architecture which requires some technical skills to learn what component functions are, computer programming, which is oriented towards learning languages and a form of qualitative logic that is needed to understand the workings of the code of the program, and then, computer networking and information technology, which is concerned with computer services and networks. In computer programming, generally very little math is required, but that is only in my experience. Pick out books or articles about certain regions of comp-sci and find your way through the subject.--Screwball23 02:02, 20 October 2005 (UTC)

My experience has been that computer science doesn't require a complex mathematical background. In completing my Bachelor's degree, I would have only encountered complicated mathematical formulas once or twice (in case you are wondering, Data Communications and a subject on Artificial Intelligence). Apart from these two instances, I think a sound knowledge of algebra and problem solving will probably get you through (bear in mind I am Australian, so maybe your education system is a bit different). Ranglin 02:56, 20 October 2005 (UTC)

However, if you want to become an computer science researcher, as distinct from a practising programmer/software engineer, mathematics skills become a lot more important. A friend of mine did a PhD in the computer science department at Princeton University; he didn't write a single computer program during that period. His work was entirely mathematical. Much of theoretical computer science is essentially a branch of discrete mathematics, there may be a lot of statistics in some areas, and many topic areas (such as computer vision) require a fair bit of mathematics.

In any case, while higher mathematics may not be strictly necessary to become a computer programmer, the mindset that it teaches you is a very valuable skill in becoming a good one. Maths is good for you :)--Robert Merkel 03:08, 20 October 2005 (UTC)

While this is generally true, it is possibly to get even a PhD in CS if you are not so good at math (although it is hard in practice). There are some areas within CS that require less math, notably systems. Having said this, it really really helps if you are good at math. First, because fundamentally programming is logic (i.e. math), and you have to be good at programming to get a CS degree. There are, however, people who are bad at math and good at programming, although this is not common. Second, to be a good programmer, you really need to understand certain concepts which are mathematical in nature (e.g. computational complexity). One thing to remember is that the kind of math one needs for CS is different from the sort of math one is used to in high school or math college courses. In particular, calculus is not especially important. Ornil 05:05, 20 October 2005 (UTC)

I first went to university hoping to score a degree in computer science. However, my high school had an experimental math program known as College Preparatory Mathematics that sure as hell didn't prepare me for college math, and I scraped by with a D- in pre-calculus, a class that didn't count toward the degree anyway. I gave up and switched to English literature. However, I know how to program; I've been writing programs of various degrees of complexity since I was twelve or so, and the most complex thing I've run into is parabolic equations. So really, even though higher math isn't seen so much in programming in the real world, you do need to have a knack for math to get a degree in computer science. Garrett Albright 14:04, 20 October 2005 (UTC)

I'm an application programmer speciallizing in CAD and database apps. While I have used advanced math up to calculus in some of the applications (calculating component masses for center of gravity analysis), this is just my case, not typical. I would say a typically programmer won't have to deal with more than basic math, perhaps time math and percentages being the limit (used for benchmarking how much faster one version of a program is than another). Knowing how to extrapolate a graph is also quite useful..."If the program can process 10 items in one second and 100 items in ten seconds, it should take how long to process 1000 items ?". If you work with graphics, some knowledge of geometry is also needed, such as the formulae for distance and a circle. StuRat 22:22, 21 October 2005 (UTC)

Excel column headings

I'm using Excel 2003. Every worksheet comes up with numeric headings at the top of columns. How can I change this to alphabetical headings? I've searched the Excel section of the Microsoft Office 2003 All In One manual but without finding a solution. I have a feeling I'm missing something pretty basic, but what?

Erasmus 02:12, 20 October 2005 (UTC)

Go to Tools/Options/General and deselect "R1C1 reference style".-gadfium 02:48, 20 October 2005 (UTC)

Thanks, Gadfium, it works beautifully. You've saved me hours of thrashing around. Erasmus.

Who manufactures the buses of the so-called "Wiki Wiki" shuttle line at Honolulu International Airport?

The buses are owned by the State of Hawaii and operated by Airport Group International. Who is the manufacturer?

Example photo: http://www.futureofthebook.org/blog/archives/wikiwikibus.jpg .

I don't recognise the badge logo, and the picture is too low-resolution to zoom in and tell that way.

Why not contact the operators and ask? --Robert Merkel 03:32, 20 October 2005 (UTC)

What are the interrelationships between science and technology?

What are the interrelationships between science and technology?

Our Technology article states: "The lines between science and technology are not always clear. Generally, science is the reasoned investigation or study of nature, aimed at finding out the truth, generally according to the scientific method. Technology is the application of knowledge (scientific, engineering, and/or otherwise) to achieve a practical result (Roussel, et.al.)." Capitalistroadster 08:09, 20 October 2005 (UTC)

• It's a very big and complex question. Scientists create technology in order to do science (think of Galileo and the telescope), but it is also often a case of a solution looking for a problem (nobody was enthusiastic about PCR when it was invented, for example, because they were worried about different problems than the one it would eventually solve). Sometimes technologies in a broader sense are derived from scientific understanding (the nuclear reactor from nuclear fission, for example), though the conversion is in no means usually simple ("reduction to practice" is often quite difficult, because no technology is reliant on elementary scientific notions alone). On the other hand, there are technologies which were created without any reference to scientific knowledge — in many cases the technology comes first and is understood by the science later.
• In short, they are very interrelated activities, and the forms of causality (what causes what) goes both ways at different times, and at times they have nothing to do with each other at all. Hopefully that answer gives you some food for thought. If you want to read an interesting book about the relationship between invention and science, I recommend Thomas Hughes, American Genesis: A Century of Invention and Enthusiasm. --Fastfission 16:54, 20 October 2005 (UTC)

CCE

What does "CCE" in various Atari 2600 games stand for? (some exposition or exhibition?) Thanks.

CCE was the (unlicensed) company that used to sell some Atari 2600 games and other stuff here in Brazil (and apparently in the rest of South America too). I suppose that ROMs with the CCE text were ripped from Brazilian\South American cartridges. EDIT: take a look at this page I found too ☢ Ҡieff | Talk 06:00, 20 October 2005 (UTC)

On another note, the company still exists and its products are worthless than junk. ☢ Ҡieff | Talk 07:43, 20 October 2005 (UTC)

Opening Matlab

I currently have Matlab installed on my computer. But when I open the program it gets to the initalising stage and then closes again. So far I have tried reinstalling windows and also resinstalling the service packs. But it still wont work. Does anyone have any ideas on the cause or solution to this problem, would be of great assistance.

• I don't use Matlab myself, so I'm probably of little help in that regard, but I'd like to tell you to be careful about reinstalling Windows. It may break settings you've had or if there's a problem, kill your computer altogether. Only try reinstalling Windows as a last resort in the future. - 131.211.51.34 07:22, 20 October 2005 (UTC)
  • Matlab seems to do a lot of thing on startup, so a diagnosis will be interesting. It may check to see how many concurrent licences are running on the network etc. Try searching Mathworks support for some help. I dug up Problems Starting Matlab which might be of some use. Good luck!--Commander Keane 11:16, 20 October 2005 (UTC)

Breakdown of a trillion dollars in ways people can easily understand.

Hello, all. I have a question/favor to ask. This question may be in a wrong column for asking, but here it is. Long time ago, I saw in a newspaper with a columnist showing and explaining just how much a trillion dollar is, in a sense of talking about national debt, and to make it easier for everyday folks to understand, there was a breakdown of a trillion dollars on this column. A broad general example would be that a trillion dollars is enough money to buy 30 NFL football stadiums, 100 3-carat diamond rings, 100 Corvettes, and still have a lot of money to buy or do other things. For some reason, a columnist's name Dave Barry comes to mind. I may be totally wrong on who this columnist was back then, but if anyone out there has any positive feedback or information or the article on it, I would really appreciate the information. Thanks.

Porc

Which trillion you're talking about? I don't know which is used in USA. ☢ Ҡieff | Talk 07:53, 20 October 2005 (UTC)

It would be the US trillion, as the British trillion is far more money than exists on Earth. StuRat 22:03, 21 October 2005 (UTC)

• According to Wordnet on answers.com, the US usage is one followed by 12 zeros see [8]. Everywhere else, it is one followed by 18 zeros. As to your question, I don't know but Dave Barry sounds plausible see [9]. Capitalistroadster 08:18, 20 October 2005 (UTC)

Everywhere else is not true. ☢ Ҡieff | Talk 09:22, 20 October 2005 (UTC)

Not to miss the point, but that sounds like kind of a crappy explanation of a trillion (american i guess) dollars. By my count, you could buy 97 $10B stadiums, 100,000 $200k Ferrari F1 Spiders, and 100,000 5 carat diamond rings (for $80k ea.), and still have money ($2 billion dollars) left. You know, for what its worth. (edited for more casual numbers). --Jmeden2000 21:45, 20 October 2005 (UTC)

I do remember a picture-based representation of how big a stack of bills you would need to represent a certain very large amount in cash, but I don't remember where I saw it (it was very impressive though). But I found this via a quick search (see second paragraph). Tzarius 10:03, 21 October 2005 (UTC)

"Unit" means "Mols"?

Hi all, a quick question. I'm doing some calculations on drug dosage, and I often come across statements like "This formulation contains 10 units of Pitocin per mL". My question is, when they say "units", do they mean "Mols"? Or is it some arbitrary unit that they've come up with? I suspect they do mean "Mols" (or "Moles"), but I want to be sure, and I can't find anything on Google. Can anyone help? For an example of the usage I'm referring to, see[10]--inks^T 09:16, 20 October 2005 (UTC)

• I'm not sure if it matters. Just ensure that your final answers are in terms of units e.g. "he should be fed 5 units every 24 hours." Charlie123 (Talk) 10:09, 20 October 2005 (UTC)

The use of 'units' or 'international units' for pharmaceuticals is in many ways a relic of the age before really high quality analytical chemistry. For a given drug or preparation, one 'unit' was the quantity of drug that produced a specific biological effect. (One unit of antibiotic X would inhibit the growth of a specific number of bacteria, for example.)

By measuring the potency of a drug through a biological effect, manufacturers didn't have to know the concentration of active ingredient (if the active ingredient was known), the concentration of different enantiomers, or the effect of different related active molecules. They just had to test each batch for biological potency and then slap a label on the jar. There's no specific conversion factor to go from 'units' to 'milligrams'; since international units are defined in terms of a biological effect, the conversion factor is different for each drug. (You can look up the conversion factor for most drugs, however.)

Now that we've gotten better at pharmaceutical chemistry, we can do two things that are gradually making measurement in 'units' obsolete:

1. We can produce very pure drugs with a single active chemical ingredient, and
2. We can measure the amount of active ingredient very precisely.

Hope that helps. TenOfAllTrades(talk) 11:49, 20 October 2005 (UTC)

• Have a look at International unit -- Rune Welsh | ταλκ | Esperanza 14:32, 23 October 2005 (UTC)

• According to Goodman and Gilman's textbook, the potency of Pitocin was originally determined by its ability to cause changes in vascular smooth muscle contraction. One unit is about 2 micrograms of oxytocin. --JWSchmidt 03:12, 24 October 2005 (UTC)

Computer upgrade

We have a set of pentium 20 computers and we would like to upgrade all our computers to pentium 4 confuguration.We had been suggested to upgrade the same by using a node concept which means to insert a card for each computer in a common server ,from where all the computers would be upgraded. We would like to have your opinion for the same.

By

shubhada

(formatting fixed --David Wahler (talk) 13:09, 20 October 2005 (UTC))

What are you trying to upgrade? Disk space? -- Ec5618 13:13, 20 October 2005 (UTC)

Maybe he wants a network-boot (PXE) setup? Tzarius 09:53, 21 October 2005 (UTC)

Instead of a single server, perhaps 2 servers would be better, allowing you to backup half at a time and still keep the others operational, for example. Also, if one server goes down you would still have half of your computers able to communicate with one another. StuRat 21:58, 21 October 2005 (UTC)

Liquid Leaking out of my hard disk

I have a white liquid leaking out of an external hard disk - any ideas what it could be? Oil for the motor perhaps?After a shave 15:42, 20 October 2005 (UTC)

What ever it is, you should back up all the data off the disk pronto! Wierd behavior from disks is a sign of imminent failure. smurrayinchester^{(User), (Talk)} 17:02, 20 October 2005 (UTC)

Are you sure it wasn't fluid that once leaked INTO the disk enclosure making its escape? Most new drives are using fluid dynamic (oil-packed) bearings but i always thought the amount of fluid was trivial and wouldnt be enough to 'leak out' anywhere if it were compromised. See Fluid bearing for more info. Is the drive behaving in any abnormal way like overheating, noise, vibration, etc? --Jmeden2000 20:23, 20 October 2005 (UTC)

Those are bits leaking out! Danger! --jpgordon∇∆∇∆ 22:55, 20 October 2005 (UTC)

Maybe the hard disk watched too much TV, or played too many games, and now its brains are turning to mush. ;) Don Diego 11:51, 21 October 2005 (UTC)

Thanks guys. The disk has gone to heaven. It was making a grinding noise before death. All data is backed up tho... I have taken it apart, and I am quite sure that no liquid got in. Ah well After a shave 15:09, 21 October 2005 (UTC)

• Obviously it means your hardrive is too wet, you should try putting in a dryer, I hear strong electromagnetic fields are good for hard drives and other data storage devices--4.237.23.16 18:26, 22 October 2005 (UTC)

How much virtual space exists in persistent worlds?

I am curious what a reasonable estimate of virual space might be in persistent worlds, such as MMORPGs. In particular, how does this amount of terrain compare with the earth.

Considerations, (please modify if so inclined)

• Equate the most common form of transport with driving a car at ~50mph.
• Estimate with and without duplicate shards or instances
• Estimate with and without non-persistent worlds, whatever persistent world is defined as...

Take it and run.. I'm not an active player on any MMORPGs at the moment, but would consider including even worlds such as LambdaMOO. My idea of space that qualifies is any electronically-provided 3D space a live individual is navigating simultaneously with other live individuals. (No, bots are not alive). ∴ here…♠ 16:29, 20 October 2005 (UTC)

It doesn't sound like an answerable question.... How big a number can you make up? Virtual terrain is just a scenery on a coordinate system, how big it is, is infinitely variable. Do you include areas from text-based games? Do you count randomly-generated dungeons? Do you count or the areas that can be gotten to, or just the populated areas? Do you count multiple instances of the same area? If you want my guess, I'd say you'd get maybe a third of a major continent from the foot-based MMOGs. If you count the flight/vehicle based MMOs, you could probably run over a few Earths. Tzarius 09:49, 21 October 2005 (UTC)

The nice part about games like CoH is that you can measure the size of the world -- it tells you. However, you also have to take into account the fact that in CoH the day is 60 minutes long, so there's a 24x time (and therefore, ostensibly, space) compression. I'm just going to give a guesstimate figure here, but given that Independence Port is about 2.5 miles long in game, at a 24x compression it'd be about 60 miles long in "real world" terms. Likewise, characters would be moving through it at 24 times their speed in game. That having been said, if you took length and width estimates, you could use that factor to calculate how many square feet exist in the CoH world. --FreelanceWizard 08:04, 23 October 2005 (UTC)

Gynecologist Paradox

I'm just perplexed, how can a male, heterosexual gynecologist still have a sex drive to have an intercourse with his wife after all day long looking at naked women? Thanks

Professionalism ☢ Ҡieff⌇↯ 17:33, 20 October 2005 (UTC)

You'll find that a lot of men do tend to bring their work home :-) but I have to admit that's one that I've often wondered about --Eye 18:53, 20 October 2005 (UTC)

• A gynecologist is not going to find every woman he works on attractive. Besides, if he gets aroused by naked women all day, why wouldn't he want to release the sexual tension and have some fun with his wife? Just looking isn't going to be enough and if he wants to keep his job he'd better not have sex with his patients. - Mgm|^(talk) 20:53, 20 October 2005 (UTC)

• A good doctor is trained to be have professional objectivity. Thus he does not think of the women as 'naked', they are patients only.

Which body parts are considered sexual arousing on sight is purely cultural. In our own society there was a time when the sight of a woman's ankles was considered sexual, so such people might well have asked us "how can you still be interested in your wife if you see strange women's ankles all day long ?". There are many societies where breasts are exposed, and a few where full nudity is practiced. In such societies, the sight of those things lose their sexual allure. Contact with those areas is another matter, however. StuRat 21:49, 21 October 2005 (UTC)

Yahoo dormant email accounts

Imagine I dont log in to Yahoo mail for many days. After how many days or months will my messages be deleted? Will my address also be deleted and recycled after a few days/months?

• Surely Yahoo! knows that answer best? - Mgm|^(talk) 20:54, 20 October 2005 (UTC)

I know that the account itself will never go away as Yahoo user accounts are permanent. -Drdisque 21:11, 20 October 2005 (UTC)

Not necessarily. Yahoo blocked my account after I didn't use ot for half a year. Unfair. Don Diego 23:01, 20 October 2005 (UTC)

But it's recreatable. User:Zoe|^(talk) 21:09, 23 October 2005 (UTC)

Consumption of electricity of speaker and fan

1) Does a speaker consume same amount of power >when the volume is low and >when the volume is maximum?

2) Does a Fan consume same amount of energy irrespective of whether it runs slow (minimum speed) or fast (maximum speed)?

No and No. However, the average power consumption of a speaker is quite low, so (barring a concert setup) you can safely assume "Yes" for the first one. Fans and other devices with motors pull more power, so it's easier to get a meaningful difference. Note that all of this, however, is relative: a desk fan's power consumption difference is probably meaningless if it's running off mains power yet significant if running off a battery. — Lomn | Talk / RfC 20:16, 20 October 2005 (UTC)

A speaker transforms electrical power into sound, so a speaker at a loud volume will be transforming more energy. Since power is the rate of change of energy, this is more power. The speaker transformation is lossy, so not 100% of the electrical power is transformed. Speakers are often rated in watts, which is the maximum power they can handle, often in RMS but some are rated at peak power. A fan turns against air and bearing friction, and similarly, draws more current as it turns faster. Dominick ^(ŤαĿĶ) 20:18, 20 October 2005 (UTC)

Buckminsterfullerene/Buckyball

What are the bond lenght and bond angle of buckyball? Some web-sites said it has single bond and double bond, while some web-sites said its bonding like benzene, is not single bond and double bond, is somehow between single and double bond. I can't find any information of the bond angle of buckyball, so please help me--

• If I remember correctly, buckyballs are made up of benzene rings in a soccer ball shape. Bonds in benzene are delocalized meaning that while you may draw the double bonds on one please there's also a structure where all double bonds are shifted one place. Since elektrons in such structures tend to move around, there's no way of knowing for certain where they are, so each of the bonds could be both single or double, which means they are something in between on average. - Mgm|^(talk) 21:02, 20 October 2005 (UTC)
  • No, buckminsterfullerene is not made up of benzene rings. It is made up of hexagons and pentagons of carbon, much like a soccerball. That means the bond angles are 120 and 108. I don't know and can't find the bond lengths right now. Also, the electrons are apparently NOT delocalized as Mgm says, and you never "know for certain where they [the electrons] are" whether they are delocalized or not. A simple google search will be more helpful to you than asking here. - Rangek 18:45, 22 October 2005 (UTC)

How about the bond angles of carbon between pentagon and two hexagons? And, is the bond lenght equal to 144pm(benzene bond lenght)?

In fact, I have searched in google, but there are not much information about details of buckyball structure. Does carbon inside buckyball have sp2 orbitals? But sp2 orbitals' all bond angles are 120 degrees. If not, which orbitals should it has?

why is the Earth a sphere

why is the Earth a sphere - ????

For a given volume, a sphere has the least amount of surface area. Bubbles, water droplets, and stars also share the same shape for this reason. Dominick ^(ŤαĿĶ) 20:21, 20 October 2005 (UTC)

The Earth is spherical because it possesses sufficient mass to (approximately) collapse itself uniformly via its own gravity. Smaller astronomical bodies of similar density (like asteroids or Phobos and Deimos, the moons of Mars) do not have the necessary gravitational attraction and remain decidedly non-spherical.

Of course, it's worth noting that the Earth isn't precisely a sphere, even if you discount mountains, etc. The Earth's rotation imparts an equatorial bulge, and (if I recall correctly) the Southern Hemisphere is generally elevated with regards to the Northern Hemisphere. You can get into more detail on this at Figure of the Earth or from Isaac Asimov's book The Double Planet (an excellent read). — Lomn | Talk / RfC 20:29, 20 October 2005 (UTC)

The equatorial bulge is, if I recall, bigger than even the biggest mountains, in the sense that the north pole is something like 8 miles closer to the center of the earth than the equator is. -- SCZenz 21:40, 20 October 2005 (UTC)

To understand the above you have to realise that the Earth is largely non-solid. Only a relatively tiny crust at the surface is solid rock. DirkvdM 15:49, 24 October 2005 (UTC)

Sudden Change

Imagine I invented a machine that could morph something say like a rhino into a banana. I put the rhino in at one end and a banana comes out at the other end. (Yes it would be a big banana). Anyway imagine that I could watch the process and this process could be viewed in ratio terms. The change would first be 99 rhino and 1 banana then 98/2 and so on. As I watched the process I would have to decide whether or not the thing I was viewing was either a rhino or a banana as it clearly could not be both. It is either one or the other. When the rhino gets down to 51/49 it is still a rhino and not a banana. A point will arise where in order to complete the process of change the morphing rhino will have to leap the divide of the 50/50 point to become a banana. I say leap because it could not be possible to exist as two things at the same time It could not exist on the 50/50 point. To one side of the 50/50 it is a rhino, to the other side of 50/50 it is a banana. If infinity exists then the process would never cross the 50/50 point because the process would be infinitely dividing down towards the 50/50 point but never quite reach it… or as it came close to the 50/50 point the process would stall … until enough pressure for change had built up to cause it to leap the divide. Would the rhino suddenly change into a banana or gradually change? Is this a fair analogy of say, changing systems in nature, where evolution stays the same for donkeys years and then suddenly there is a big change. Or physics where an atom can absorb so much energy before suddenly jumping up to a higher energy level. Or say global warming, will our earths weather system under go a sudden change if enough pressure builds up? How close could we be to that change? Will I ever stop asking questions? :-) --Eye 20:24, 20 October 2005 (UTC).

IMHO, this is not a fair analogy, no conclusive proof has been offered for global warming, and the notion is unfortunatly unable to be determined given the political climate. In many places things have been getting hotter, and in some colder. Superimposed on this is the warming and cooling that occurs over centuries. At one time Greenland was pretty pleasent, and able to grow crops, now it is not. Dominick ^(ŤαĿĶ) 20:30, 20 October 2005 (UTC)

Your analogy describes a Zeno paradox which, while an amusing word play, doesn't really enter into reality—despite all arguments to the contrary, Achilles really will outpace the tortoise. That said, some transitions in nature mirror this: electrons exist at distinct energy levels. However, macroevolution is more correctly viewed as continuous, as are trends in global climate. As for the final questions, they're philosophical. — Lomn | Talk / RfC 20:34, 20 October 2005 (UTC)

Just read some of the Zeno thingy. Isn't life fun.. :-)--Eye 20:45, 20 October 2005 (UTC)

An infinite series of times can actually add up to something non-infinite. Say you're doing the last percent, and you're "infinitely dividing it" - so 51%, 50.5%, 50.25%, 50.125%..... But, you need to remember you're also dividing up the time needed to perform the task. Also, pretend you have a super-camera that takes a picture every time you "divide it". If the process takes, for example, 100 seconds, you're taking "snapshots" at 49 seconds, 49.5, 49.75, 49.875..... You might be taking an infinite number of "snapshots" (and you can assemble them into an infinitly long movie), but your snapshots don't slow down time! Also, the first half of a percent takes half a second, then the next quarter takes a quarter of a second, then the next eighth takes an eighth....and it all adds up so that the last 1 percent takes 1 second. There's no paradox at all. AySz88^-^ 20:52, 20 October 2005 (UTC)

• In chemistry substances that change into others often have transition states which is a form in between the other two, which is actually neither rhino nor banana (if I were to keep to your analogy). Technically speaking, the rhino would stop being an actual rhino the moment it wasn't 100% rhino anymore. - Mgm|^(talk) 21:06, 20 October 2005 (UTC)

The rhino/banana thing was actually part of another thing I was thinking about to do with acid/alkaline. (Since you mentioned chemstry.) If the same analogy was used as the above rhino/banana scenario would a solution be classed as an acid until it became an alkaline? Is it possible to have a perfectly neutral solution?--Eye 22:29, 20 October 2005 (UTC)

Theoretically, yes. In the real world, small impurities are excluded, so a very, very weak acid could be classified as a neutral solution, until the basicity rises significantly. Regarding your rhino, maybe halfway through it would be a Very Confused Rhinoceros, Unless You Put the Head In First, In Which Case, It Would Be A Very Blissfully Ignorant Fruit. Incidentally, time flies when you're having fun, but fruit flies like bananas (and rhino-bananas, ergo). ;) Don Diego 22:58, 20 October 2005 (UTC)

I think you had better start by building a rhino-banana machine, and find out. Seriously though, you mentioned that the process was transitioning at one percent per measured interval, 100/0, 99/1, 98/2, etc. and it would have no reason to change as it approached 50/50. I have a machine that turns water into ice, and it doesn't slow down and stop for any so-called 'halfway'. The postulate you are hinting at is something that quantum physics is trying to deal with, in particular the Uncertainty principle. When is something what it is, and not something else? The basic answer is that as you measure it, it is what it is, and beyond your ability to measure it, it lies in an uncertain state, ready to jump to any possible state only when youre ready to come along to find out. It's been suggested that many thresholds apply to our universe, mostly from physicist Max Planck who suggested that there is a point beyond which it would require infinite energy to make an accurate measurement, and since that's not possible, for all you know everything exists in quanta of that particular level, and no more detail is possible. There is much reading available on the subject. --Jmeden2000 17:23, 21 October 2005 (UTC)

Regarding the comparison with evolution, I don't believe evolution ever moves "instantly" from one species to another, but do believe it moves quicker at times and slower at other times. We might choose to classify one individual as one species and it's offspring as another, but that is just due to the way we classify things, there wasn't necessarily a large jump between the two individuals. I would say periods of rapid evolution happen due to changes in environment (including the food supply and predators) and enabling changes in the species itself. In primates, for example, the opposable thumb originally evolved as a way to hold onto tree branches, but enabled tool use as well. This led to a rapid evolution of intelligence in primates to make use of this capability. StuRat 21:33, 21 October 2005 (UTC)

solubility of hydroxylapatite vs. pH

I am trying to find out how the solubility of hydroxylapatite depends on pH. I have searched through a number of reference books, but I've been unable to find an answer. Ideally what I would like is a chart of pH vs. solubility for this mineral. Thanks if you can help! ike9898 20:51, 20 October 2005 (UTC)

If you have access to scientific journals, through a library or university, you could have a look at some of the articles that appear on this Google scholar search. -- Rune Welsh | ταλκ | Esperanza 14:19, 23 October 2005 (UTC)

Red/turquoise contrast problem.

I have noticed that if a strong red and a turquoise or blue-gray border on one another, I find it very difficult to look at. It's not a kind of colour-blindness, because I can clearly see the difference between the two; actually, it's more like the contrast is too great to see properly. The border appears to sort of crawl and it is unpleasant to focus on. If I see these two colours bordering one another even in my periphery it is distracting, almost as if something is blinking or moving in my periphery. Does anyone know what this is? Is it common? Bryanmtmorrison 21:01, 20 October 2005 (UTC)

I have experienced that also, and discussed it with others, so I can tell you that other people see the same thing. ike9898 22:07, 20 October 2005 (UTC)

While the area we focus on sees the most detail, the periphery is good at detecting movement. In your case it sounds like the "threshold" for seeing movement is too low, and you eyes/brain detects movement that isn't really there. StuRat 21:19, 21 October 2005 (UTC)

Carbon

what are 4 uses of carbon?

You can use it to do your own homework--see the rules at the top of this page. But I bet reading our carbon article would be a real good place to start. -- SCZenz 21:38, 20 October 2005 (UTC)

Plants Of The Amazon Jungle

While watching a programme on T.V. I came across an unfamiliar word- Aseyi Berry- it si supposed to be the berry of palm trees. I am not certain of the spelling.

You'll be wanting our Açaí Palm article. :) --Ashenai (talk) (Galatea!) 22:42, 20 October 2005 (UTC)

white film on magnesium strip, plz help ASAP

Ok, before doing an experiment, why should you polish and remove white film off a magnesium strip?

That white film is a layer of magnesium oxide, which forms when magnesium is exposed to air. Presumably, you want to do an experiment on magnesium, not magnesium oxide, so you first must clean the film off to get down to the magnesium underneath. — Laura Scudder | Talk 23:22, 20 October 2005 (UTC)

well, do you want to experiment on pure magnesium, or do you want your results tainted by the presence of oxidation and impurities? Lethe | Talk 23:23, 20 October 2005 (UTC)

On pure magnesium, THANK YOU VERY MUCH

How to find experimental percent composition of magnesium and oxygen in Magnesium oxide?

How do you do such thing?

Please do your own homework. Hint: Mass increase. -- Ec5618 23:39, 20 October 2005 (UTC)

These are a little bit complicated, can some one help? To be more exact, I started with 0.16 g of Mg after heating it, I ended up with 0.24g of MgO. I want to find the experimental percent composition of magnesium and oxygen in Magnesium oxide.

Bigger hint: have a look at the articles on magnesium and oxygen and find out the atomic mass of each. From that you should be able to figure it out.

No, that will give you the theoretical percent composition. Oxygen is rarely analysed in elemental analysis, magnesium is usually analysed by atomic absorption spectroscopy. Or maybe your teacher just wanted you to say that your 0.16 g of magnesium are still present in your 0.24 g of magnesium oxide... See also Antoine Lavoisier. Physchim62 03:53, 21 October 2005 (UTC)

Actually, not just the theoretical mass distribution. When you burn the magnesium, it will gain weight. A negligible amount of magnesium will be lost. Where did that 0.08 grammes of weight come from? 0.005moles of .. Ok, I'm done hinting now. -- Ec5618 11:35, 21 October 2005 (UTC)

• Surely we've got a magnesium oxide article? - Mgm|^(talk) 08:16, 22 October 2005 (UTC)

Are you sure you burned all of your magnesium. It may be better to use a thinner wire or shavings so it burns completely. - Mgm|^(talk) 08:18, 22 October 2005 (UTC)

Coulombs law

How does one calculate a question like this:

Two charges with specified values for charge, which are held a distance apart, an extra charge is introduced and is moved along the line they are on. Where would the new charge experience a zero resultant force?

---MJH

Set up a coordinate systemm that seems easy to you, like putting one of the stationary charges at x=0. Add up the forces from each of the two charges (from Coulomb's law) on the extra charge, making sure the signs are right for the directions they point. Then solve algebraically for when the sum of forces is zero. -- SCZenz 00:08, 21 October 2005 (UTC)

Can you elaborate a little more? What do you mean by sum?

Normally it would be a vector sum, but in this case the problem is one dimensional. I mean write down the force from coulomb's law from each charge separately, using your chosen coordinate system for both (your r's will have to be changed), and then literally add up the numbers. (Make sure the signs are right to reflect the direction of the forces!) -- SCZenz 00:35, 21 October 2005 (UTC)

Internet Protocol

Question: what is a Level 2 Internet Security Protocol

Answer: do your own homework. Hint: Find out what level 2 means by starting at OSI model. --Robert Merkel 13:27, 21 October 2005 (UTC)

Also compare SSL and IPSec. --R.Koot 15:46, 21 October 2005 (UTC)

(Neither of which is a level 2 protocol.) Gdr 10:55, 22 October 2005 (UTC)

rosenberg generator

hi wikipedia. myself rutuparna andhare. i want to know information about the rosenberg generator. this is a special purpose m/c. i want its construction, working and digram. my e mail id is (removed)

Hi Rutuparna. You might need to try some books on electrical engineering for this kind of detail; all we have at Wikipedia is the article on motor controller. Maybe some electrical engineering or mechatronics people will be able to give you some more specific help. Sorry I can't be of more assistance. --Robert Merkel 11:53, 22 October 2005 (UTC)

I am an EE, and I used to teach. I have not used or been in contact with a "Rosenberg generator" if you have any basic details, I would love to fill in the article. I think it is a DC Motor/generator, thats only by looking at litarature that didn't say much except what I told you. Amusingly enough, google returned some link to the free power and perpetual motion crowd. I found no vendors for such an item, but I have not looked at the stack at my workplace. If you want someone to build you one, or tell you how to build one, this is beyond the scope of wikipedia. Dominick ^(ŤαĿĶ) 14:07, 22 October 2005 (UTC)

Light in a box

Why can't you trap light in a mirrored (on the inside) box? When I first asked my dad this, he told me that if you cut off the source of the light when shutting the lid, the wave can't exist inside the box. This doesn't satisfy me, however, because light can still travel through space, and, indeed, be bounced off mirrors, after a star has died.

Say light is coming from a distant star. I bounce it off one mirror and set up another mirror far away parallel to it. Would it keep bouncing between them? The energy decreases rapidly with distance because it all disperses, sure, but the same would not be the case in an enclosed-on-all-sides box.

I'm guessing that it's because the mirrors absorb energy with each bounce and that, in the tenth of a second it takes me to close the box and open it again, the light has bounced around a zillion times and lost all its energy. Is that right? And would it be theoretically possible to have a perfect mirror in which this energy loss (if that's what it is) didn't occur?

• Sure it's possible. In fact, there are perfectly legitimate standing waves of light in classical electromagnetism. And yes, what really happens if you bounce light a lot is the energy gets turned into heat on the walls of the box. -- SCZenz 04:43, 21 October 2005 (UTC)
• If you can rig up a strong enough magnetism or gravity source, you can trap light without having it lose energy, just by keeping it in a stable orbit. (which might be a bit tricky with magnetism). Tzarius 09:34, 21 October 2005 (UTC)

light is neutral, and so will not be affected by electromagnetism (neglecting quantum effects). Gravity would work, however. but the radius of a lightlike orbit is on the order of the Schwarzschild radius, so if you want to trap light with gravity, you'd better have a black hole handy. -Lethe | Talk 09:46, 21 October 2005 (UTC)

• But there is light inside a box, just light that you can't see. When the light bounces off the walls, it doesn't lose all its energy, it shares that energy with the walls of the box. When everything has calmed down (very, very quickly), the light and the walls have the same "energy" (strictly, the same temperature), and you can't tell them apart. See also black body radiation. Physchim62 12:50, 21 October 2005 (UTC)

• The very best mirrors that you can make use special optical coatings and reflect about 99.999% of the incident light (in a narrow wavelength range). They are used for cavity ringdown spectroscopy. If you place a pair of them 0.5 m apart, light bouncing between them drops to about 0.1% of its starting intensity after 345000 round-trip bounces, or about 1.1 milliseconds after the light starts. So even with extremely good mirrors, and ignoring all other factors, the light doesn't stay around for very long. --Bob Mellish 15:45, 21 October 2005 (UTC)

I Like this kind of question. Think of another.--Eye 16:49, 22 October 2005 (UTC)

how to prepare soft drinks?

Prepare them for what? Could you please clarify your question a bit more? -- Daverocks 12:03, 21 October 2005 (UTC)

See, for example, OpenCola. TenOfAllTrades(talk) 13:04, 21 October 2005 (UTC)

Some simply open the container and drink it. You open the cap and pour it over ice. A slice of lime as a garnish is sometimes used. Optionally, rum can be added to Cola, to make a Cuba Libre. In rural areas of the United States cola without rum it is a common breakfast beverage. Soft drinks without coloring, preferably lemon lime flavors, can be used to clean automotive battery terminals. Dominick ^(ŤαĿĶ) 14:14, 21 October 2005 (UTC)

It's only a Cuba Libre if there's a lime. Without the lime, it's a Rum and Coke.  :) User:Zoe|^(talk) 21:05, 23 October 2005 (UTC)

If you are asking how they are prepared in restaurants, most use a machine which blends soda water (seltzer) and syrup. Bottled soda (premixed) is sometimes also available. StuRat 21:01, 21 October 2005 (UTC)

lightning?

can the energy (electricity) in lightning be saved or stored? why, how or why not?

mckeancharles@(email removed)

I suppose if you had a really big capacitor hooked up to a lightning rod, you could store the electricity, but all in all, you would save about 500 Megajoules, or 139 kilowatt hours, which would save you between £8 and £15 pounds ($15 - $25) (at 6p per kWh). Not all that worth it. smurrayinchester^{(User), (Talk)} 14:15, 21 October 2005 (UTC)

BTW, don't post your email address here. Spammers read this page too. smurrayinchester^{(User), (Talk)} 14:17, 21 October 2005 (UTC)

The problem is that lightning is so irregular that collecting it would require millions of lightning rods all over the collection area. The strength of each bolt is quite different, too, so you would need to be able to handle the maximum case to prevent your equipment from getting fried. Then you would need an efficient way to store the energy until needed. The cost of all this far exceeds the benefit, at least at the currrent cost of electricity. Perhaps some future technology, like balloons carrying thin metal fibers, can make it profitable. StuRat 21:09, 21 October 2005 (UTC)

Mind you, actually, if lightning strikes the Earth 100 times a second as some people say, covering the entire planet in lightning conductors could save about £800 per second, or £69,120,000 per day. Of course, the cost of installing the billions of rods needed would probably take years to recoup. smurrayinchester^{(User), (Talk)} 09:32, 22 October 2005 (UTC)

One billion rods with collection mechanisms and connectivity to the power grid would be rather expensive, especially those built in Antartica, over oceans, etc.

Let's say they could each be built for £1,000,000. That would put the total cost for 1,000,000,000 rods at £1,000,000,000,000,000. At £69,120,000 per day that would take 14,467,592 days to pay off, which is close to 40 thousand years. I doubt if they would last that long.

A more practical approach would be to only place rods in areas of frequent lightning strikes, like the top of hills in areas of frequent thunderstorm activity. I still doubt if such a system could be made profitable, however. StuRat 14:29, 22 October 2005 (UTC)

I suspect it's still a losing game. The CN Tower in Canada (according to our article) is struck by lightning about 75 times per year. The Empire State Building (according to various offsite pages) gets about a hundred strikes per year. If we optimistically assume that the best locations are three times that good, then we get three hundred strikes per year times twenty dollars per strike: $6000 per year. (That assumes that the storage and redistribution of the electrical energy is 100% efficient.) I can tell you that storing a 500 megajoule lightning strike is going to cost a lot more than that.... TenOfAllTrades(talk) 14:54, 22 October 2005 (UTC)

I'm not convinced by any of this millions of rods stuff. Lightning takes the route to Earth that has the least electrical resistance. By definition that's where it needs to go. If there's a whopping great capactitor in the way it'll avoid it. Shantavira 16:04, 22 October 2005 (UTC)

Crocodilians in Guatemala

I've been watching this season's edition of the reality show Survivor, which takes place in Guatemala. The contestants are living in two camps along the banks of some unnamed river. This river is infested with lots of crocodilians. Now, the contestants and the host keep calling these things "crocs". "Oh, so-and-so was almost eaten by a croc!" "The winning team will receive a swim cage, 100% croc-proof." But I could've sworn that Central America had alligators and not crocodiles. Searching around on the web, I've found the same confusion on various websites.

So which is it? Does Guatemala have alligators or crocodiles? What's menacing these people? And are they really known man-eaters? --BrianSmithson 14:06, 21 October 2005 (UTC)

Both caiman and crocodiles [11] [12] are in Guatemala. Krieky! Alligators (new world 'gators) are in the lower United States. [13] I used the University of Florida site, also known as the Gators. Such reptiles till attack a lot of things moving in murky waters, but do not prefer human flesh to other types of food. Dominick ^(ŤαĿĶ) 14:20, 21 October 2005 (UTC)

P.S. The Caiman is classed as an alligator, but is not the common 'gator that you may be familiar. Dominick ^(ŤαĿĶ) 14:22, 21 October 2005 (UTC)

Muchos gracias! For the first few episodes, I kept screaming, "Those aren't crocs, you idiot! Those are alligators!" Guess I should be voted out of the tribe. I suppose the animals they keep showing could be caimans, though. BrianSmithson 20:58, 21 October 2005 (UTC)

I may be totally talking out of my hat, but I believe you can tell caimans from crocs by their teeth -- when the mouth is closed, you can't see a croc's teeth, but you can see the caiman's. User:Zoe|^(talk) 21:03, 23 October 2005 (UTC)

All about health

Q1. For how long has a brush been in use that will reduce its plaque removing ability up to 30% than a new one?

Q2. How many hours does a baby spend in a baby walker that will delay its first step by up to 4 days?

Q3. Less than how many hours of sleep a night will run a person 2 to 3 times the risk of heart attacks?

Q4. What waist measurement or over is thought to increase a person's risk of getting a heart attack?

Q5. How long did people need to train with weights per week in order to lower their risk of coronary heart disease by 23%?

Q6. After what age would people start losing muscle mass and strenght caused by hormonal changes?

Q7. What % of man who took annual holidays would be less likely to die of a heart disease than those who'd skipped time off?

Q8. How many mililiters of cooked soya beans would contain the protein equivalent of a 110 gram hamburger or 500 mililiters of milk?

Please let me the answers. My email address is <removed> Thanks and regards Raj Ramoo

Almost all of these questions suffer from a problem of overspecificity. They ask a question that due to natural variability in the subject, there cannot be a specific answer to the question. For example, in #1 variation in material used would likely have a great impact on the length of use before it's usefullness declined. Also many of these may or may not have ever been specifically researched, or if they have, to use the first one as an example, the toothbrush companies keep the information secret to try to gain a competitive advantage. In other cases, such as #7, there may be a certain study that found a number, but that doesn't mean that number is accepted fact, and wouldn't be contradicted by another study. Again, the variation is just too great. - Taxman ^Talk 15:29, 21 October 2005 (UTC)

Water

If 84% of sea water is evaporated every day, why isn't water salty? Please have the answer in soon. Contact my email: (removed)

If you read the top of this page, you'll find that we don't reply by email. But to answer your question, it's because the water evaporates and leaves the salt behind. (I'm not sure what your 84% statistic means though. -- SCZenz 15:05, 21 October 2005 (UTC)

I'm positive that statistic is false. --Quasipalm 18:05, 21 October 2005 (UTC)

Well, "why isn't water salty" doesn't exactly make sense. Sea water is, indeed, salty. --Borbrav 20:57, 21 October 2005 (UTC)

I think he/she means why isn't all water salty. - Akamad 23:51, 21 October 2005 (UTC)

In that case, river and lake water is continually replaced by fresh water, in the form of rain, and the salt is washed out to the ocean. An exception is a terminal lake, which does not lead to the ocean, then salt does accumulate. Such lakes, like the Dead Sea in Isreal/Palestine and Salt Lake, Utah, USA get extremeley salty, even more salty than the oceans. The only limit is when the salt reaches it's solubility level in water and deposits on the shores and bottom of the lake. StuRat 14:10, 22 October 2005 (UTC)

Some bodies of water do not get salty, if there is no salt in the surronding geology to leach into the water. Fossilized water, water stored underground that is not flowing, sometimes is not salty. Florida has a few depositsof water that do not flow, and do not get salty. I think the OP was wondering if "84%" of the water evaporated why are the oceans not supersaturated. The answer is that 84% of the water does not evaporate. Dominick ^(ŤαĿĶ) 14:16, 22 October 2005 (UTC)

INDIA

Development of India in the field of science and tecnology.

Without a complete question it's hard to determine what it is that you're looking for. Perhaps you should read the article on India and its associated articles and then maybe come back with a more solid question. Dismas|^(talk) 17:12, 21 October 2005 (UTC)

• India has developed. To the extent that it knows to put an "h" in technology, and much more. It will continue to develop. If you want a better answer, do your own homework!. Physchim62 17:13, 21 October 2005 (UTC)

• You could look at articles in Category:Science_and_technology_in_India. Indian science might be a good starting point. -- SCZenz 17:14, 21 October 2005 (UTC)
• And please realise the search box is on the left of the page. -- Rune Welsh | ταλκ | Esperanza 14:05, 23 October 2005 (UTC)

concerning the ontological status of dimensions.

Hello, My question is, what is the ontological status of a dimension? Is its status objective, i.e., a characteristic of reality or of a thing in reality (these are different answers) or subjective, i.e., a way in which we perceive reality? Thank you, Arnon Shahar. --217.132.229.134 17:55, 21 October 2005 (UTC)

As a scientist, I have to say I'm not sure how we would tell. Assuming they're a property of reality is very helpful in making physical models. Also, there are physics models with an extra dimension, or even 7, but they include evidence of why we don't see such things normally. -- SCZenz 19:34, 21 October 2005 (UTC)

Partial vs total differentiation

The Stackelberg competition article gives the condition for a Nash equilibrium as ${\frac {\partial \Pi _{1}}{\partial q_{1}}}=0$. I don't see why this uses a partial derivative, rather than a total derivative and asked the question (with more details) on Talk:Stackelberg competition#term missing a while ago. Can anyone confirm or refute my suspicion that this is an error, please? Common Man 18:25, 21 October 2005 (UTC)

mathematically, it seems to depend on whether q1 and q2 are independent or not. I don't know anything about economics, so I'm not sure. The phrase "given the output of the leader (firm 1), the output that maximises the follower's profit is found" seems to suggest that q1 should be regarded as fixed (given) and the value of of q2 which maximizes with respect to that fixed q1 is sought. In that case, the partial derivative is correct. -Lethe | Talk 19:07, 21 October 2005 (UTC)

You're right - your argument holds for the value of q2. So the first pair of equations (involving Pi_2) need to consider the partial differentiation. Now that you pointed this out, I see why someone would use partial differentiation for Pi_1, for the sake of symmetry. It's clearly more elegant. But is it right? (Drilling further down, I realize that this distinction is somewhat arbitrary anyway. Arguably, the Pi_2 equation seems like a mongrel between a partial derivative (with q1 constant) and a total one, since P and C_2 are explicitly differentiated. This is getting ugly!) Common Man 20:09, 21 October 2005 (UTC)

Incidentally, could someone take a stab at clarifying the beginning of the article? Speaking as a layperson, I'm having real trouble figuring out what the heck Stackelberg competition actually is. TenOfAllTrades(talk) 20:39, 21 October 2005 (UTC)

As a start, noted that the context of the article is in game theory. Ancheta Wis 22:09, 21 October 2005 (UTC)

Thanks for the answers, but this is actually, as the headline says, a question about partial vs total differentiation. I'm neither an economist or game theoretician either. But trust me, you don't have to be one to answer the original question. It is pure mathematics. As a first step, maybe I should ask the following context-neutral question:

Given

f = f(x,y,z)

y = y(x)

z = z(x)

We know that

df/dx (where y=constant and z=constant) is called partial derivative

df/dx (where y=y(x) and z = z(x)) is called total derivative

What do you call

df/dx (where y=y(x) and z = constant)

and what's the mathematical notation for it? Common Man 22:36, 21 October 2005 (UTC)

It is a partial derivative as well. For a boundry condition? My experience in calculus is for electromagnetics, not game theory. Same notation: ${\frac {\partial f}{\partial x}}$ Dominick ^(ŤαĿĶ) 23:37, 21 October 2005 (UTC)

You can borrow some notation from thermodynamics, (but is also used elsewhere). Suppose f = f(x,y,z). Then

$\left({\frac {\partial f}{\partial x}}\right)_{y,z}$

is the partial derivative of f taken with respect to x keeping y and z constant.

But in the context of this question, it seems that you want to define

$\left({\frac {df}{dx}}\right)_{z}$

and this generally does not really make much sense. You need some sort of transformation to rigorously define what you would like to do here. --HappyCamper 15:50, 22 October 2005 (UTC)

I have seen ${\frac {\partial f}{\partial x}}{\Bigg |}_{z}$ but you are right, it is vague. I made it clear in text, but rarely it was an issue except at a boundry. Dominick ^(ŤαĿĶ) 14:43, 23 October 2005 (UTC)

Really? I didn't know that notation was in use too. That explains a few things now in another paper I was reading. I kept on thinking that it meant ${\frac {\partial f}{\partial x}}{\Bigg |}_{x=z}$, in other words, differentiate with respect to x, and then evaluate the result for x =z, which seemed to be highly redundant. --HappyCamper 14:55, 23 October 2005 (UTC)

Calculus is hard to express without good shared notation. Partial derivatives are done where more than one variable may change. They differ in from the "full" derivative only when a value is fixed. I would prefer to write ${\frac {\partial f}{\partial x}}{\Bigg |}_{z=0}$ or ${\frac {\partial f}{\partial x}}{\Bigg |}_{z=1.23e4}$ assuming f(x,y,z) still contains the y variable. The partial derivative will only get really different than a full derivative when I increase the order, for some reason writing, ${\frac {\partial ^{2}f}{\partial x\,\partial y}}$ but thats a different headache. Dominick ^(ŤαĿĶ) 17:55, 23 October 2005 (UTC)

Thank you, guys, that settles the terminology and notation. (I will use Dominick's form for the fist equation with Pi_2 after explaining it somewhere). So what do you think about the second equation (with Pi_1)? To keep economy and game theory out of it - what they do is simply: Find the maximum by setting the derivative to 0 (and hoping that it isn't a minumum or saddle point). For this, they should use the total differential, so the current formula lacks a term, correct? (Maybe that discussion should be kept at Talk:Stackelberg competition#term missing.) Common Man 01:43, 24 October 2005 (UTC)

What are the bond angles of buckyball?

They are 120 and 108 degrees, aren't they?

Someone asked that earlier today. — File:Ontario trillium sig.pngmendel ☎ 20:41, 21 October 2005 (UTC)

No one answered it though, so are they 120 and 108 degree?

No, they must be less than 120°, otherwise you would have flat sheets as in graphite. Physchim62 12:18, 22 October 2005 (UTC)

Peak busy hour

Generally, what is the percentage of total daily calls that occur during peak busy hour in a voice network?

• What country are we talking about? - Mgm|^(talk) 08:26, 22 October 2005 (UTC)

PRODUCTION FUNTION CURVE (**** URGENT****)

WHY WE ARE PRODUCING PRODUCT AT THE POINT WHERE THE CURVE STARTS DECLINING?

PLEASE SEND ME THE ANSWER WITHIN 6 HRS OF MY QUERY, AS IT IS VERY IMPORTANT TOPIC FOR ME.......

Respectfully, ___ Muthukannan S. B.E, MBA MADURAI (INDIA)

If I understand the question, it falls into the general category of "why should a company produce additional units at a lower than optimal profit margin". There could be many reasons for this:

• They want to maximize the amount of profit, not just the rate. While a 10% rate of return on a million dollars is better than a 9% return on a million, a 9% return on a two million may well be better than either, depending on your perspective. A single owner of a company would rather have the 180,000 profit that would generate than the 100,000 profit in the previous case.

• The larger production may allow a greater market share, which will then lead to greater future profit amounts and rates.

• They may have significant fixed costs which are better divided among many units than a few.

StuRat 20:46, 21 October 2005 (UTC)

Can you be a bit more specific who "we" is, and which product and which curve you refer to? WRT "Respectfully": Using all caps is regarded as shouting, which is not considered respectful. Nor is setting deadlines without explanation. Common Man 20:32, 21 October 2005 (UTC)

Is his homework due in six hours? TenOfAllTrades(talk) 20:37, 21 October 2005 (UTC)

It is because that is the point where marginal cost begins to exceed marginal benefit. - SimonP 20:41, 21 October 2005 (UTC)

space shuttle

what factors did the engineers consider when designing the tiles for the space shuttle?

This seems like a homework question, but I'll give you the benefit of the doubt. Ceramic tiles are able to withstand intense heat. They need not resist great (bending) forces, but they need to be able to cope with vibrations. Because of this, the tiles are connected to the main body of the shuttle via a dampening support frame. The tiles probably have variable thickness, too.

As the article states, that the original silica-based ceramic tiles need to be removed for inspection for damage after every flight, and they also soak up water and thus need to be protected from the rain. The latter problem was initially fixed by spraying the tiles with Scotchgard, but a custom solution was adopted. Later, many of the tiles on the cooler portions of the Shuttle were replaced by large blankets of insulating feltlike material, which means huge areas (notably the cargo bay area) no longer have to be inspected as often.

See Thermal Protection System. -- Ec5618 23:45, 21 October 2005 (UTC)

Apart from the reasons in the excellent response above, weight is a critical issue. Although they are ceramic, when I saw a TV scientist mucking around with an old Space Shuttle tile it seemed to have a density resembling foam rather than the tiles we have in our homes.--Commander Keane 00:16, 22 October 2005 (UTC)

Of course, they must not only withstand heat, but also act as effective insulators to prevent that heat from reaching the shuttle body. StuRat 02:26, 22 October 2005 (UTC)

AIDS

Is it that a person infected with AIDS will sure die ??

we can be sure that everyone dies in the end, with or without AIDS -01:47, 22 October 2005 (UTC)

Assuming you meant to say "...die from AIDS", then no, for several reasons:

• Medications exist which seem to be able to prevent, indefinitely, death from AIDS. The "AIDS cocktail" seems to be effective, although very expensive. In some patients, they seem to develop a drug resistant strain of AIDS. This can be managed by changing the mix of medications, however, at least in the short term.

• "Infected with AIDS" is rather vague. Some people are HIV positive, meaning they have been infected by the virus, but never show any symtoms of AIDS. These people appear to have a natural immunity. Interestingly, the same immunity from the bubonic plague also appears to offer immunity from AIDS.

• Genetic engineering may offer a way to extend this immunity to all people within a few years. So, if someone with AIDS can survive until then, they may be cured.

StuRat 02:14, 22 October 2005 (UTC)

• People don't get infected with AIDS, but with the HIV virus. When this happens they are HIV positive, but it may take many years before they even show the slightest sign of having AIDS. Some people never develop the symptoms and die of other causes. So while people do die in the end, AIDS may not neccesarily be the cause of their death. StuRat was right. There's drugs that slow down the disease allowing the infectee to have a fairly normal life without having to worry about dying, provided they do regular checkups with their doctor. - Mgm|^(talk) 08:31, 22 October 2005 (UTC)

• Every human will surely die, regardless of whether they have AIDS or not. -Drdisque 16:28, 22 October 2005 (UTC)

• Ask Magic Johnson. It seems HIV+ people with enough money can battle AIDS for a very long time. --Quasipalm 17:17, 22 October 2005 (UTC)

• Also note that people with aids usually die because of so-called "opportunistic diseases". These diseases wouldn't normally kill a healthy person with proper access to healthcare, but are a serious danger to people who have developed AIDS. -- Rune Welsh | ταλκ | Esperanza 13:52, 23 October 2005 (UTC)

• • You all forgot one reason: They might get run over by a bus or something. A tonne of steel moving at 80 kph doesn't discriminate between HIV-negative and -positive people. — JIP | Talk 16:27, 24 October 2005 (UTC)

Equation editor on Word

Is there a shortcut to get the equation editor on Word 2003? Or do you have to go to Insert>Object>Microsoft Equation Editor everytime? A way to get it on the toolbar would be handy. Thanks Akamad 07:04, 22 October 2005 (UTC)

• No idea about Word 2003, but under older versions you could go to the Tools/Customize... menu, choose the "Commands" tab, then category "Insert", and scroll down to find an "Equation editor" button which you could drag to any toolbar. I suspect it should work the same way in new versions of Word. --Bob Mellish 07:19, 22 October 2005 (UTC)

Thanks kind sir :-) That works nicely. As it turns out you can also assign keyboard shortcuts from the same place, which is exactly what I wanted. Akamad 07:45, 22 October 2005 (UTC)

Hmmm...I added it both to my toolbar and assigned it a keyboard shortcut, but they are not there when I restart Word. Any ideas? Thanks :-) Akamad 09:05, 22 October 2005 (UTC)

Make sure that Word is saving the toolbar changes to Normal.dot, not just the current document. I know under Word XP there's a clear drop-down box which has the options of saving either to Normal.dot or just the current document. If you're getting to it the same way in Word 2003 (through the Tools/Customize menu), it should have it there as well.

That should work, but if you're sure it's saving to Normal.dot ("sure" as in you can clearly see the option is Normal.dot), then you can create a macro in Word which will automatically do anything. It's under Tools -> Macro -> Record New Macro. You can assign the shortcut to the macro to toolbars or keyboard, but either way, make sure it's saving the macro to Normal.dot. When you finish saving the macro settings, it will start recording the macro. Then get open the equation editor the way you usually do it, and stop recording the macro. Then you can use this macro later to instantly do what you just did. -- Daverocks 10:30, 22 October 2005 (UTC)

I think there is something wrong with my Normal.dot file, because anything I save to it seems to be gone when I re-open Word, I might try re-installing Office. Thanks for your help :-) Akamad 00:34, 23 October 2005 (UTC)

Toothpaste Vs Charcoal

I need to write an essay on Toothpaste, its history, the devolopment procedures of toothpaste (including any equations or formuals and why it was made) and any benifits to this compound. I also have to write the same information about charcoal and how it can be used as toothpaste and i need to write the positives and negatives side of using toothpaste instead of charcoal. As you can tell, I'm having no difficulties finding information about the toothpaste side, but i am finding it extremley hard to find some information abut the charcoal side. Any information about charcoal and toothpaste would be of great use to me.

Thank you

A google search for charcoal toothpaste [14] reveals pages like this: [15]. I'm not recommending that page in particular, but you could look around like that. Our article on toothpaste may help also. -- SCZenz 09:29, 22 October 2005 (UTC)

Thank you for your reply, but i am still in need for more information about charcoal. I have already looked up the sites that you advise me too see and managed to find some information about toothpaste but not charcoal. Again thankyou for your help and any information about charcoal would be of great use to me.

You might try asking on camping forums. When I was a Boy Scout I was told that in a pinch, chewing coals from a fire (which had cooled first of course) cleans teeth. Since I was told this on a camping expedition by someone who was instructing us on various ways to use nature I would think that someone on a camping forum may know more about using coals in this fashion. Dismas|^(talk) 15:57, 23 October 2005 (UTC)

Do wild animals snore?

I guess they don't. An animal that snores would always attract predators or alert preys. Such a genetical feature shall be eliminated by natural selection in no time.

I also don't think ancient humans and earlier hominids snored much. I guess snoring marks the rise of our undefeatable human civilization where men in bed are no longer eaten by big cats. As a result, bad genes are not eliminated and people start to snore. -- Toytoy 10:08, 22 October 2005 (UTC)

From the New York Times

Q. Do any animals besides people snore?

A. Yes, some animals do snore, according to anecdotal reports and personal observations, said Penny Calk, manager of the mammal collections of the Bronx Zoo.

"Some that we have observed are dogs, gorillas and bears," she said.

The mechanism of snoring in these mammals probably resembles what happens in people. In human beings, according to The American Medical Association Encyclopedia of Medicine (Random House), snoring is noisy breathing through the open mouth produced by vibration of the soft palate, the back part of the separation between the oral and nasal cavities. It is more common while people are sleeping on the back, as the lower jaw tends to drop open. Snoring is caused by anything that hinders breathing through the nose. Gnats

Evolution sometimes 'picks' traits that don't seem to make sense to us for a variety of reasons -- for example, they may be a side effect of some positive trait or may increase herd health overall. For example, you may think that sleep itself should also be eliminated by evolution at some point simply because laying about in the wild unconscious is certainly the easiest way to become lunch -- however, the positive impact of sleep probably makes it worth it. There are other examples, like take homosexual animals and humans, which seem to be in a number of populations, despite obvious limitations on reproduction. And of course, evolution isn't finished, and never will be finished, so that there are current 'issues' with current models is to be expected.  ;-)

(You might point out that animals in the zoo don't face evolutionary pressures either, so that's why they snored, but I would assume that gorillas and bears have been captive for a small enough number of generations to not have evolved in any major way. Another thought: maybe if bears and humans and gorillas and dogs (former wolves) snore, it could be a sign that only the animals least prone to becoming the lunch of other predators have the evolutionary leeway to get away with snoring -- could be an interesting theory. "Origins of the snoring species." ) --Quasipalm 16:48, 22 October 2005 (UTC)

Dogs have been selected by human for thousands of years. Some dogs now look so unnatural that they cannot survive in the wild for a day. Since a dog breeds in a couple of years from birth, the evolution or devolution of its anti-snoring features can be several times faster than us humans.

Bears and gorillas are on the top of the food chain. Maybe they do not afraid to be eaten by all these lovely rabbits and hamsters at night. Maybe, I guess.

As to the majority of animals that are much smaller than humans, I guess they don't snore because their breathing is less of a problem. And as to the other ones much larger than us, maybe their soft palates are much thicker and vibrate at much much lower frequencies.

Do some bigger chimpanzees snore? Do some bigger orangutans snore?

Did these long-neck sauropod dinosaurs snore? Did the fattest T.rex snore? Survival the fattest! -- Toytoy 19:56, 22 October 2005 (UTC)

How do dogs recognize each other?

File:SW3vader.png

Sob! My dog will never recognize me again! George Lucas go to hell!

Dogs of different breed can be very different from each other. How does a Dalmatian recognize a Chihuahua?

Humans are not dogs. How does a dog recognize humans? A person can wear a red T-shirt today, a black tuxedo tomorrow. How does a dog (color blind) learn to disregard some but not all visual signals? How many house pets can recognize their owners if the clothing, smell (perfune) and facial features (shaved or not; hair cut; cosmetic makeup; eye glasses) changes? Can a guinea pig does that? Can David Prowse's dog recognize him if he wears the Darth Vader suit? -- Toytoy 10:53, 22 October 2005 (UTC)

Dogs recognize other dogs as dogs because they smell of dog. Smell is much more important than sight to a dog. Shantavira 16:12, 22 October 2005 (UTC)

Dogs have been selected by human for the past thousands of years. How did they manage to keep all these intercanine communication protocols? I mean you breed a new kind of dog based on its human usable features (look, ability to hunt, alertness ...). Maybe by some God-initiated accident, the best retriever in the world may smell like a cat! What a tragedy! I mean a dog that does not smell OK to the "Head Beagle" survives if it helps its owner make or save money. How can a dog intelligently designed in Yorkshire and another one intelligently designed in Beijing know each other? -- Toytoy 20:11, 22 October 2005 (UTC)

OK, a dog owned and bred by human still needs to have sex with another dog to beget puppies. Maybe this partially explains my question. If no other dog wants to have sex with your blue-ribbon retriever, you cannot breed it. No dog wants to have sex with your lousy gold medal. No way. They have to smell each other's anal gland so they can have sex.

What will happen if we perform artificial insemination on dogs? Will they lose the ability to recognize other dogs one day? -- Toytoy 20:25, 22 October 2005 (UTC)

If we eliminate the last threads of survival of the fittest, and instead cause all dogs to reproduce, this will eventually lead to degradation of the species to a level where they lose many abilities, including the abiity to smell. Purebred dogs already have many health problems, such as hip displasia, as a result of breeding. Salmon in fisheries were bred by the fish equivalent of artificial insemination (cutting them open to mix the eggs and milt) and suffered a rather alarming degradation of the species as a result. StuRat 20:58, 22 October 2005 (UTC)

I think basic reproductive functions will still be there. You still need to form good-enough sperms and eggs. And with mammalian animals, a female needs to have a working uterus even if you perform cesarean section in the end.

I always believe today's people have more inherited diseases than their ancestors. Maybe one day, many people will have degraded eyes and some other degraded complex organs. -- Toytoy 21:40, 22 October 2005 (UTC)

I heard some where that a dog can recognise more smells than we can recognise colours, for example, if two colours of red were so close we couldn't tell the difference, if those reds were smells, a dog could tell the difference.--Eye 19:23, 22 October 2005 (UTC)

I live on the 4th floor and my dog can notice my arrival at about the time I enter my apartment silently. Sound of footsteps can be a clue. I just don't know which senses they use and which ones they exclude. How do animals know a human changes clothing and makeup everyday so if one person's torso looks much darker than he/she was 2 minutes ago, that's still OK? I guess high intelligent social animals know their owners better.

Pets can learn, to some extent. The first time you came home wearing a bear suit, they likely would be rather frightened until they identified your voice and smell. However, the next time they would know that is within the range of clothing you wear. Pets also tend to think their image in a mirror is another animal, the first time they see it. After a while, they know better.StuRat 20:58, 22 October 2005 (UTC)

Do pets other than cats and dogs (hamster, chicken, snake, horse ...) recognize owners so well? -- Toytoy 19:39, 22 October 2005 (UTC)

Intelligent animals like a horse, pig, or parrot, yes. Stupid animals like a fish or chicken, no. StuRat 21:02, 22 October 2005 (UTC)

I think the "Human Recognition Algorithms" used by dolphins must be different from the ones used by dogs. Maybe a scientist can intelligently design a human dress code to fool 90% of dolphines, 10% of dogs and 100% of people and another to fool 10% of dolphins, 90% of dogs and still 100% of people. -- Toytoy 21:23, 22 October 2005 (UTC)

Most animals know who feeds them. A lady with long blonde hair feeds red kites in Wales. The only other people who can feed them are people with long blonde hair, (or blonde wigs)--Eye 20:06, 22 October 2005 (UTC)

To my original suggestion I would add that instinct is a very strong motivation, probably the only motivation in lower animals. When a dog sees anything trotting down the street on four legs its instinct is to investigate to see if it can have sex with it, chase it, sniff it, fight it, or play with it. It probably doesn't have a concept of "dog" but responds to it instinctually according its reaction to its smell and behaviour. Also dogs tend not to be too fussy what they have sex with. A dog is clearly shown "shagging the cat" in one episode of The Osbournes. Shantavira 10:15, 23 October 2005 (UTC)

Windows XP log on screen

Ages ago when I was messing around with the computer at my parents' house trying to do something that doesn't need going into here, I somehow lumbered it with starting up with the Windows XP network long-on screen every time it boots up, even though the computer isn't connected to a network. There's no password set so it can be quickly gotten rid of my hitting the enter key, but it's still an irritant, and for the life me me I can't work out how to get rid of it. I've tried all sorts of things in the control panel and so forth, and Windows online help is sod all use. Can anybody help with this one? I'd be much obliged if so. Angmering 10:47, 22 October 2005 (UTC)

Maybe turn on the "Welcome" screen under User accounts? I don't know if you can do that under XP Professional, but you definitely can on Home Edition. Although I suppose it would still require you to click the name on the Welcome screen to get on to the computer. You could try reinstalling Windows XP, but maybe you should try get some other help before doing that. I don't know an exact way to get rid of it, but there must be some value in the Registry that toggles on and off automatic logon. Does anyone know that? Alternatively, use a Linux distro as your operating system instead. -- Daverocks 12:42, 22 October 2005 (UTC)

Help identifying frog photo

A Green Tree Frog, Hyla cinerea?

This morning, I saw a frog on one of my sliding glass windows. I took a bunch of pictures of it. Can anyone help me identify which frog breed it was so I can upload the batch to the Commons? This picture was taken in south Florida (north Palm Beach County). Neutrality^talk 15:31, 22 October 2005 (UTC)

Green Treefrog [16] (hyla cinerea) according to the UF website [17]. Dominick ^(ŤαĿĶ) 15:39, 22 October 2005 (UTC)

Thanks! Neutrality^talk 16:03, 22 October 2005 (UTC)

I wish I lived in a place where I could see such a creature on my window. :-( --Eye 16:54, 22 October 2005 (UTC)

Frog, Part II

OK, I wrote an article on American green tree frog. Two requests:

• First, can someone tell me the full name of "Schneider," who apparently first described and classified the species in 1792?
• Second, can somebody fix the taxobox in the article? Something messed up and now the entire article is in the taxobox!

--Neutrality^talk 18:49, 22 October 2005 (UTC)

Fixed. He was Johann Gottlob Schneider. Gdr 19:21, 22 October 2005 (UTC)

Nice job! Dominick ^(ŤαĿĶ) 14:45, 23 October 2005 (UTC)

Thanks, Gdr! Neutrality^talk 21:20, 23 October 2005 (UTC)

Saliva Spray

Does anyone know what it's called when saliva sprays from underneath your tongue toward the back of your mouth? I've never heard of this spoken of, but have experienced it, as has at least one other member of my family. Theshibboleth 16:29, 22 October 2005 (UTC)

In America, this can be called "gleeking" or "gleek." [18] It may be called something else too, and I'm not sure if it's slang. I suppose the formal way of saying it might just be "salivate," or "projectile salivation."  ;-) --Quasipalm 17:05, 22 October 2005 (UTC)

I wonder if there's a photo in the commons of someone doing a saliva spray.--Commander Keane 17:21, 22 October 2005 (UTC)

I have seen such a photo. It was published around 1972 in an anatomy text for medical students (Becker maybe?). Unfortunately not something we can use here. alteripse 04:28, 23 October 2005 (UTC)

Nicotine

For years, I've been told that nicotine can stunt the body's growth. Is this a fact? Thanks, Dave.

I'm not actually sure, however, nicotine and smoking do cause bloodvessels to narrow, inhibiting the supply of blood throughout the body. This can certainly cause problems with growth, though that would hardly be the most pronounced effect on the body. -- Ec5618 17:44, 22 October 2005 (UTC)

• I suppose it could retard your production of NAD+ and thus might have some effect on lipidbiosynthesis, and hormone regulation, but then I don't know how your body deals with pure nicotine--4.237.23.16 18:19, 22 October 2005 (UTC)

Elementary biochemistry error here. The problem with this speculation is that it forgets the difference between signal effects and metabolite effects. Nicotine is a signal molecule, like hormones and neurotransmitters. All of its effects result from this and the needed amount for this type of effect is tiny. On the other hand, for a metabolite to competitively interfere with a basic metabolic process that occurs in multiple forms in most cell systems, requires order of magnitude higher tissue concentrations (far more than can be delivered by your basic nicotine delivery device). The names should not be so similar because it tempts the novice into this confusion. Furthermore, a large proportion of the adverse effects of smoking are not attributable to the nicotine-- the nicotine is just the reward that perpetuates the addiction but is only a small fraction of the substances ingested. alteripse 15:24, 23 October 2005 (UTC)

Cigarette smoking can stunt your growth if your mother does it, before or after you are born. The evidence for mild prenatal stunting is strong, the evidence for postnatal (i.e., secondhand smoke effects) weaker. Unless you are idiot enough to turn mild asthma into severe by heavy smoking in early teens, your own smoking won't affect the last couple of years of remaining growth. Although most smokers start as children, most of the adverse systemic effects that might interfere with growth take several years to accumulate.alteripse 04:30, 23 October 2005 (UTC)

T-Rex

In the article on Tyrannosaurus rex, I'd like to include the number of T-rex fossils (incomplete or otherwise) ever found. Does anyone have a reputable, current source? -- Ec5618 18:10, 22 October 2005 (UTC)

Maybe you could visit your local university and check out paleontology journals, like The Paleontological Society and JOURNAL OF DINOSAUR PALEONTOLOGY. You may also find access to some of them online. --Quasipalm 01:11, 23 October 2005 (UTC)

Museum Victoria says "there are now parts of more than twenty-one individuals known from western USA". T. rex fossils are also found in Canada; National Geographic magazine comments on "the wealth of T. rex fossils already found—more than 30 to date". Gdr 09:51, 23 October 2005 (UTC)

Good to the Last Drop? or is it?

Is maxwell house coffee considered instant coffee, or just bad coffee?--4.237.23.16 18:21, 22 October 2005 (UTC)

It is one of several brands of instant coffee, a beverage derived from, but really quite different from, coffee. Plenty of people buy it, so it can't be that bad. Not to my taste though. Shantavira 18:27, 22 October 2005 (UTC)

Maxwell House makes both instant and regular coffee: [19] — File:Ontario trillium sig.pngmendel ☎ 05:45, 23 October 2005 (UTC)

You'll never get the answer to the question "Is MH considered .. bad coffee" here or anywhere else. There is no answer that would satisfy everybody, and there is no final arbiter of the truth when it comes to personal taste. If a person doesn't like it, the only truthful statement about that circumstance is "He doesn't like it". JackofOz 11:46, 23 October 2005 (UTC)

How calculators work

I was wondering if someone could explain to me how calculators work. I have looked all over the internet and I can't find anything. The Wikipedia article on calculators doesn't explain how they work, and its not on howstuffworks.com. Madsci.org has a page about it but it's written for a child and not very detailed. Thanks. --Taylor

• It rather depends on what level you want it described. Nowadays, the simple type of calculator is a small, dedicated computer, with no external RAM, just a dedicated CPU (a simple one, nothing much more than an ALU), probably a built-in ROM containing its control program, and an interface to the display and keypad. (More complex calculators with programmability etc., will have external RAM and are in effect small general-purpose computers). If you read up on how a CPU works, that will cover just about everything. In the past, calculators were probably made from digital logic chips, but CPUs are so cheap now I doubt that's cost effective. --Bob Mellish 19:57, 22 October 2005 (UTC)

What are the differences between a $0.75-cheap solar-powered giveaway calculator and a low-end engineer calculator today? Do they use the same core chip? I guess it could be cost-efficient to manufacture a general-purpose calculator chip based on 6502 or Z80 than to manufacture two or more.

Does a dirt-cheap calculator use a floating point-based number format internally? Or does it use fixed-point arithmetic? Do they follow IEEE standards (e.g. IEEE floating-point standard)? Maybe not, I guess. These old CPUs only have integer ALUs (+ and - only). So you write your own floating- or fixed-point programs with or without following standards. -- Toytoy 21:02, 22 October 2005 (UTC)

A common project used to be design an ASMD calculator, where the student would create the spec, and some of the logic. IIRC, the math details were not specified as part of the project. In any calculator, the implementation varies, and it can be anything from a processor, to a FPGA or a PLD. I usually use a simple test to evaluate designs, many fail this test, including the MS windows calculator in basic mode. Type 1+2*3 the correct answer is 7 if the calculator uses order of operations correctly, the incorrect answer is 9, this means the calculator evaluated (1+2)*3. Most calculators don't tell you the internal float format, and you shouldn't care. If you really need to know, like for astronomical calculation, then you should not be using a pocket calculator. Dominick ^(ŤαĿĶ) 11:38, 23 October 2005 (UTC)

I guess if you want to mass produce something cheaply, you will not use FPGA or PLD, will you? There must be some widely used generic calculator chips. -- Toytoy 16:20, 23 October 2005 (UTC)

Kangaroos

Do male kangaroos have pouches or is it just the females? If so why?

This is like the "men's nipples" question that has been discussed recently. A pouch is more costly than nipples on a male kangaroo. But if without it on a female kangaroo, it will be a disaster. I don't own a male kangaroo so I cannot answer your question directly. But I guess the answer is yes. As you know, animals were designed by an intelligent but inexperienced designer who did not spend a couple of minutes to undesign men's nipples and male kangaroos' pouches. God, someone please teach that lousy designer a biological lesson! -- Toytoy 21:10, 22 October 2005 (UTC)

A pouch on a male kangaroo would be a disaster as well because they rip at each others bellies when they fight. Is there an aussi amongst us who could settle the question?--Eye 21:25, 22 October 2005 (UTC)

Who needs an aussie when you've got an encyclopedia? Our article on marsupials begins, "Marsupials are mammals in which the female typically has a pouch." (Boy, it's hard to read articles on marsupial or monotreme reproduction without wondering if the articles have been vandalized. Strange critters.) Of course the trivial answer to why only the females have pouches is "because that's how they evolved", but it might help to note that the primary sexual characteristics of mammals tend to be unique to one sex. — File:Ontario trillium sig.pngmendel ☎ 05:36, 23 October 2005 (UTC)

Pages per Minute

When a printer says '15 pages per minute' or whatever, what is it printing? Certainly, I can never get more than 7 pages of normal quality text or 1 or 2 pages of photos from a printer in that time. smurrayinchester^{(User), (Talk)} 20:57, 22 October 2005 (UTC)

I once read that the PPM measurement is based on a 10% page coverage. It might have been 15% or 20% or even 5% - I can't remember the exact figure - but it's a ridiculously small amount, particularly when dealing with photos. --Pidgeot (t) (c) (e) 00:43, 23 October 2005 (UTC)

When they state "X PPM", look for the fine print elsewhere on the page that specifies the conditions under which the test was conducted :)--inks^T 04:02, 23 October 2005 (UTC)

Such figures are indeed usually about printing pages with a low coverage (meaning the percentage of the page that gets ink on it) - 10% would be text with plenty of open lines. And it will also normally refer to the fastest printing option with low quality. 4 seconds per page doesn't sound too strange for a modern printer. Mine approaches that. The problem with these figures is that they're only about one little aspect and between printers it's not even standardised, so they don't even serve for a comparison. Best ignore them. It's just the company showing off with useless info. DirkvdM 18:52, 24 October 2005 (UTC)

Recent Mergers

I would like to know a large merger that happened in the last 6 months. I mean a really big merger between two well-known companies. If it made news in the NY Times or a large newsource, that would be good. The reason is simple: there aren't any. I can think of plenty of large car company hybrids, but no large mergers between banks, auto companies, anything these days. Name one and I'd be happy to read it.

Symantec merged with Veritas, in the single largest merger of software companies to date. The original intention to merge was announced in December 2004, but the actual merger took place in July 2005, after regulatory approval. See List of Symantec acquisitions.-gadfium 03:59, 23 October 2005 (UTC)

US Airways acquired America West Airlines -Drdisque 03:58, 23 October 2005 (UTC)

Why?

I reformatted by computer, now for some reason my computer no longer has the right codec to play .WMV files?? How can this happen? Shouldn't the one codec a clean restore leaves you with be the windows media format?! I mean, isn't that odd? how can I get it back?Thank you for helping me--help me 03:51, 23 October 2005 (UTC)

Even some types of .WMV files need external codecs to play. Before you formatted, you may have had the popular ffdshow codec. If installing that doesn't solve your problem, try using DivX. However, it's more likely that ffdshow will solve your problem. -- Daverocks 08:46, 23 October 2005 (UTC)

I would suggest downloading VLC media player -- it's built with a ton of codecs built into the system so you don't have to worry about not having the right one or downloading new ones. --Quasipalm 14:19, 23 October 2005 (UTC)

I second Daverocks. To elaborate on his comment: Just like for an .AVI file or a QuickTime file, a .WMV file may have been encoded with any video codec. The fact that it has a .WMV suffix doesn't necessarily mean it was encoded with any particular codec. Some mad scientist at Intel may be encoding video right now with an exotic codec he wrote himself, and the files he's generating are .WMV files. Then embedded within the .WMV file, there's an indication of which video codec was used. When you do a regular install of Windows Media Player, you get a collection of codecs that Microsoft wrote or has licensed, but some other popular codecs are not included, most notably Divx. Tempshill 03:00, 24 October 2005 (UTC)

Why do women wants unproportional breasts?

I am puzzled, why some women like to enlarge their breasts so big that it looks unproportional? I think natural is better.

It's a cultural thing, particularly in the United States. I think it might be less common than it was a decade ago. See Breast implant#Risks_and_controversy.-gadfium 05:09, 23 October 2005 (UTC)

A few years ago I heard that plastic surgery in the USA is usually enlargement, whereas in France it's usually to make them smaller, so that would indeed make it a cultural thing. I also suppose it's about what women think men want and that might be influenced by porn movies and such, which represent fantasies that men would not want to encounter in real life. Or maybe the movie makers get it wrong too, leaving the men with little choice. DirkvdM 19:05, 24 October 2005 (UTC)

How do male kangaroos urinate?

From marsupial:

Males usually have a two-pronged penis which corresponds to the females' two vaginas.

I don't think there are too many Aussie porn movies created for their marsupian population. How do these animals piss?

I really don't know anything about these strange creatures. Just 10 minutes ago, I thought Joey is a man who sells hot dogs at a street corner. -- Toytoy 05:54, 23 October 2005 (UTC)

Twice as efficiently? I guess "aim" is not important to a kangaroo. However "two-pronged" is a little suspect. Please see these delightful pictures of single-pronged kangaroo penises. Shantavira 10:44, 23 October 2005 (UTC)

Great pics! Do we have an article on kangaroo penis to put them in? alteripse 15:16, 23 October 2005 (UTC)

Marsupials have a cloaca [20] [21] that is connected to a urogenital sac in both sexes. Waste is stored there before expulsion. Urine does not exit through the forked penis. Dominick ^(ŤαĿĶ) 20:15, 23 October 2005 (UTC)

Quantifying universal indicator paper.

Does anybody know if you can quantify the use of universal indicator paper. I have thought about putting the paper through a spectrophotometer to get a quantitive result; but is this the best way to go about quantifying this data. I have also considered the use of a pH meter but dismissed this route.

If possible, use a pH meter. It's easier.

Otherwise, you may want to use a drop of Universal Indicator without the paper part. If you cannot buy it, prepare it by yourself. It's more difficult to obtain a good reading from light reflected from paper. You can take the absorption spectrum of that drop of indicator. You also need to calibrate your system. Personally, I think calibration is a difficult job because external factors such as temperature and other impurities can affect the color of that drop of indicator. -- Toytoy 10:32, 23 October 2005 (UTC)

Exactly. The whole point of indicator paper is just to give you an approximation of the pH of a solution. If you need anything accurate a pH meter is the way to go. -- Rune Welsh | ταλκ | Esperanza 13:33, 23 October 2005 (UTC)

*shudder* - there are things much, much, much better than pH meters - the fact that you mentioned a spectrophotometer makes me wonder whether this is for a paper or such? How accurate do you need the result to be? --HappyCamper 14:52, 23 October 2005 (UTC)

In answer to the above question from "Happy Camper" I just need a way of quantifing my results from Universal indicator paper. Will the spectrophotometer work with just the paper.?? By reflecting the light or something to that extent off the paper.

Ah, I see what you are looking for. Well, check out spectrophotometer and analytical chemistry. From the first article, it says "Perhaps the most common application of spectrophotometers is the measurement of light absorption, but they can be designed to measure diffuse or specular reflectance." Hmm...I wonder...If you use one of these machines, would you mind taking a picture of it and donating it to Wikipedia, provided that it is compliant with the GFDL? :-) --HappyCamper 00:12, 24 October 2005 (UTC)

I think if you work for a paint company you need to measure diffuse or specular reflectance everyday. -- Toytoy 14:04, 24 October 2005 (UTC)

Street lamps' color

Why are street lights generally orange colored? I've heard that they increase visibility, are cheaper to produce, and that they attract fewer bugs -- but I have no idea which of these are true (if any). --Quasipalm 15:26, 23 October 2005 (UTC)

I think it might have more to do with running (electricity) costs rather than detracting bugs. In the Sodium vapor section of the History of street lighting in the United States article, it says that the sodium vapor lamps use the least amount of power compared ot other types. Street light also has a bit of info. --Commander Keane 15:53, 23 October 2005 (UTC)

Just in case you don't know, the color of street lamps is based on the gas contained within the lamps. They aren't intentionally colored with colored glass, if that's what you were thinking. StuRat 17:41, 23 October 2005 (UTC)

Last time I visit Los Angeles, I found they don't switch off street lamps at noon! (Outside the LAX airport.) If they only switch on lamps when it's dark, it'll save some money. -- Toytoy 16:24, 23 October 2005 (UTC)

Some lights are on timers and others are on photoelectric cells that turn them on when it gets dark. Both systems can fail, however, and I suspect that's what happened in LA-X. StuRat 17:41, 23 October 2005 (UTC)

The chief (and probably only) virtue of sodium vapor lights is the energy efficiency. They actually create problems with visibility due to the unnatural color; our eyes are evolved to work best with white light, as from the sun. Because of this, there is a movement now toward metal halide lamps.--Pharos 18:18, 23 October 2005 (UTC)

Several yeras ago, many cities on Southern California went around covering every other street lamp on every street with black plastic, so the sensors didn't detect that it was becoming night, and turn on. The idea was to reduce the cost of running all of the lamps every night. But through the years, the black plastic has deteriorated and now hangs in shreds and all of the lights come in at night anyway. I always wondered why covering the sensors with black plastic didn't make the sensors think it was perpetual night, and cause them to burn all the time, but apparently it didn't. User:Zoe|^(talk) 20:49, 23 October 2005 (UTC)

Agree with Pharos -- the yellow streetlamps are sodium lamps, chosen for their efficiency, in places where you don't need to recognise colours. I seem to recall using a sodium lamp in a high-school physics experiment for something, presumably because it transmits only a narrow band of that yellow colour (when it's warmed up; they're pink/red when cold) Ojw 22:01, 23 October 2005 (UTC)

I remember one time I had gone to a concert in San Francisco with some friends, and had parked in a parking garage. It was late at night when the show ended. We went to go find my car. We walked around the garage several times without finding the car, and for a while we were afraid it had been stolen… But who would steal a cheap Suzuki Swift? Eventually, we found it, and also why we had trouble noticing it before; the fiercely orange light of the parking garage was making my red car look purple! Garrett Albright 04:09, 24 October 2005 (UTC)

What is food transfer?

Well, it's the transfer of food between two places. A quick googling shows that food transfer is used as a term in the food and beverage industry for "food transfer equipment" (such as tubing for beverages) and also in the term "regurgitative food transfer" about how some animals vomit food to share it with other animals in their herd. --Quasipalm 18:12, 23 October 2005 (UTC)

Settle a bet - about a freezer

In the long run, is it more energy efficient to keep a freezer empty or full? Jooler 20:17, 23 October 2005 (UTC)

If you were to never open it, there would be no difference, since the flow of heat into the freeser depends only on the difference of temperatures between the inside and the outside, the surface area of the freezer, and its thermal conductivity. However, if you were to open it, I'd say that an empty freezer would have more of the cold air inside replaced with warm air than the full freezer, so the extra warm air would need to be cooled down. The warm air in the empty freezer would have negligible thermal capacitance relative to the walls, and the heat loss would be unaffected. The cooling of this extra air would require energy, so the full freezer would have a slightly lower consumption of energy and thus be more "efficient" (as in usage of energy per unit of time). --Borbrav 21:30, 23 October 2005 (UTC)

I disagree. If you have a lot of stuff in your freezer, once it all warms up it'll take a lot more energy to cool it because it has a lot more mass. -- SCZenz 21:36, 23 October 2005 (UTC)

But then you don't normally keep your freezer open for the time it takes to cool down the actual items in the freezer. --Borbrav 21:41, 23 October 2005 (UTC)

I suppose the heat capacity of the air is negligible to that of any solid item in the freezer. Also, to just halve the amount of air you'd really have to stuff the freezer (if you still want to be able to access anything in a practical way). So the amount of air seems irrelevant. And I can't think of another factor off hand, so I'd say there's no difference worth mentioning. DirkvdM 19:17, 24 October 2005 (UTC)

Neodymium ions

Are there any ions in neodymium if so what is its most common? Thank You Dennis S

Have you looked at our Neodymium article? -- SCZenz 20:14, 23 October 2005 (UTC)

Info on boron

I am doing a paper on Boron for humans. Would like an y relevent info. Joe Cambell

Boron as trace element for human diet? As a therapeutic agent? As a useful element for making things for humans? alteripse 21:21, 23 October 2005 (UTC)

Try Boron. Dominick ^(ŤαĿĶ) 21:24, 23 October 2005 (UTC)

See Boron#Applications and Boron#Precautions. Neutrality^talk 21:32, 23 October 2005 (UTC)

Help identifying bird and plant species

Unknown bird species

Unknown bird species

Unknown gladiolus species

Unknown gladiolus species

Can somebody help identify this bird and gladiolus? And, if possible, it would be great if someone could touch up the photos (all I have is lousy Picasa). Neutrality^talk 21:31, 23 October 2005 (UTC)

Sandhill Crane (Grus canadensis) [22] Dominick ^(ŤαĿĶ) 21:43, 23 October 2005 (UTC)

Isn't that a common Bougainvillea? Dominick ^(ŤαĿĶ) 21:45, 23 October 2005 (UTC)

Oh, yes....you're quite right, I meant to say bougainvillea. Guess I'm not much of a botanist. ;) Neutrality^talk 21:48, 23 October 2005 (UTC)

Interesting distribution [23] IMHO, they are making a real presense in Florida. In the Ocala forest they are thick as thieves. They are also non-migratory[24]. Dominick ^(ŤαĿĶ) 23:18, 23 October 2005 (UTC)

alcohol

To what extent does alcohol cause brain damage?

• Have a look at the article Effects of alcohol on the body. -- Canley 01:39, 24 October 2005 (UTC)

reproductive organ

is it true that if you dont use it you will lose it--65.175.226.190 23:40, 23 October 2005 (UTC)

Wikipedia does not give medical advice →Raul654 23:41, 23 October 2005 (UTC)

Unscientifically, no organs have ever fallen off for disuse. People in general, never lose organs, unless they are detached in trama. Dominick ^(ŤαĿĶ) 00:02, 24 October 2005 (UTC)

I don't want to upset our inquirer, but haven't you ever heard of disuse atrophy? alteripse 01:25, 24 October 2005 (UTC)

Am I supposed to know what this is about? Maybe I haven't watched enough US adolescent movies :) . DirkvdM 19:22, 24 October 2005 (UTC)

bases/acids to catalase

what will happen if bases/acids are added to catalase-containing materials? What will happen if hydrogen peroxide is next added?--172.199.133.7 04:24, 24 October 2005 (UTC)

In order to help you with your homework, I suggest you read the article on catalase as well as Base (chemistry) and Acid. Dismas|^(talk) 05:14, 24 October 2005 (UTC)

Making an unfair die fair

To make an unfair coin fair, one can use the following trick

If a coin is bias then it cannot be used as a fair coin. But if the rules of the game is changed to properly rely on when the coin gives a certain result, the coin can still be used to produce a fair result. John von Neumann gave the following procedure :

  1. Toss the coin twice. Note down the first "result" and the second "result".
  2. If the results match, start over, forgetting both results.
  3. If the results differ, use the first result, forgetting the second.

Note: This procedure only works if the tosses are paired properly. If part of a pair is reused in another pair, the fairness may be ruined.

My question is this:

Is there a way to make an unfair dice fair? Ohanian 06:16, 24 October 2005 (UTC)

The equivalent procedure, for an N-sided die, would be:

1. Roll the die N times; note each result.
2. If any of the results match, start over, forgetting previous rolls.
3. If all the die rolls are different, use the first result and forget the rest.

Obviously this is a very inefficient procedure. -- SCZenz 06:28, 24 October 2005 (UTC)

I'm impressed by this procedure. If I ever play dice with the devil, I'll insist on these rules.-gadfium 07:51, 24 October 2005 (UTC)

If I were the devil, I'll give you a die or a coin that's so unfair that it will never give you anything other than head or 1. Analysis:

• Possibility of H-H pair: 1*1=1
• Possibility of H-T pair: 1*0=0
• Possibility of T-H pair: 0*1=0
• Possibility of T-T pair: 0*0=0

(Proof for the die follows the same logic.)

You lose. I win. I am evil. Who cares about you? Don't think you can outsmart devil. -- Toytoy 13:54, 24 October 2005 (UTC)

Its actually called a die (singular) or dice (plural). This method would help to make an unfair die fair. -- Ec5618 08:00, 24 October 2005 (UTC)

Polya Frequency Distribution

I am trying to find details for the Polya Frequency distribution. They are referred to as PF_infinity, PF_2, etc. From what I recall they are some kind of limit or not a limit of the sum of exponentials. I can't find them on Wikipedia, or Google.

The bigger problem is that I need the sum of 2 independent exponentials with different parameters.

Regrds, Abhijit Roy

GFP

I need some information on the concerns regarding the effect GFP tags have on the behaviour of proteins, but searching for "concerns" "GFP-tagged protein" on Pubmed and Clusty only gets me experiments and papers where they were used.

Has anyone got an idea on how to refine my search, or can someone point me to a good resource on the subject. I've got the basic issues down, but I'd like to be more thourough. - 131.211.210.17 09:27, 24 October 2005 (UTC)

Don't use "concerns" in a scientific literature search. It is a reflection of your state of mind or valuation of something but the gap between denotative meaning and common connotative usage is too large to be a useful coding term. If you are concerned about actual risks, then search for "risk" as a term. If your concern is whether use distorts the function it is being used to measure, search for a general review of GFPs and scan for one from a methodology journal, and you should find a discussion of the issue. If neither of those is your "concern", I can't even guess and you will need to spell it out more plainly for us. alteripse 11:32, 24 October 2005 (UTC)

• That question was me. I was looking for iterature that discusses the effect the tagging has on the function of the proteins that are being studied. - Mgm|^(talk) 17:59, 24 October 2005 (UTC)

I don't know much about this particular method but would start by looking for some review articles about the method itself to see if there is a discussion of your question, which now makes sense to me: If you tag a protein to observe it, does that change the behavior of the protein in an important way? Sounds like a good question. I assume that early work on the method compared the results obtained by GFP tagging with results obtained by other methods. Have you looked at any of the more recent volumes of Methods in Enzymology if you can't find anything online? As a last resort, call or email someone who has written one of the reviews and ask if they know of any examples in which the method gave misleading results because the tagging interfered with the protein. alteripse 20:59, 24 October 2005 (UTC)

Chemistry

why is the valence of alkali metals always 1? The reason for this is because those elements have a single electron in their outer shell. When this electron is removed by a chemical reaction with an electron deficient element (like Chlorine) the element is more stable because the inner shell is filled.

Gas collection mechanism

First thanks for answering my earlier question on sun & planets gear & epicyclic gearing. This one is rather more theoretical. Is there at present any sort of semi-permeable material which would allow specific gasses (such as CO2 & Ozone) through into a balloon or other container but not let them out again. Would it be able to do this at normal pressure & therefore collect CO2 directly from the atmosphere, through some sort of osmosis or would some sort of pump be required to pump in air to the balloon & pump out all the air less the CO2. My reason for asking is that I had the thought of collecting CO2 in massive dirigibles/balloons & towing them to Mars to start off an atmosphere there. I also thought of taking gasses such as Ozone from a gas giant such as Neptune & towing them to earth to fill the hole over Antartica. I know we don't have the rocketry technology to do this right now but can we do the gas capture with current (or expected) technology? AllanHainey 13:56, 24 October 2005 (UTC)

Osmosis (which is just a special case of diffusion) only takes place from areas of high concentration to areas of low concentration. If you tried to construct such a balloon that was permeable only to carbon dioxide, you'd find that the diffusion would stop as soon as the concentration of CO₂ reached the same level as the outside air (i.e. thermodynamic equilibrium). That's not to say it can't be done, however, but it would require some kind of energy input—for example, continuously removing out the CO₂ to keep the diffusion going.

On the other hand, I believe other methods of gas separation are more commonly used and efficient. The standard method I learned in chemistry class uses refrigeration fractional distillation to separate the gases out according to their different boiling points. As for your idea about the ozone layer: the hole in the ozone layer is primarily caused by compounds like chlorofluorocarbons that break down ozone. If those chemicals are removed from the atmosphere, the ozone is naturally regenerated by ultraviolet light. Until that occurs, any other measures taken will probably be relatively ineffective. --David Wahler (talk) 17:04, 24 October 2005 (UTC)

You;d need one hell of a lot of CO2 to make a dent. Actually, if you'd construct rockets that produce CO2 as a waste product to use that, you'd probably need to send an amount of rockets that would cripple the economies of all countries in the world. I guess. Even if you'd collect all the waste CO2 in the Earths atmosphere (before it gets exhausted would seem most efficient) that wouldn't be enough because the climate change effect is largely caused by a small difference in consentration. I think. Hope my guessing and thinkng have helped any. DirkvdM 19:34, 24 October 2005 (UTC)

The chlorofluorcarbon effect on Ozone is still a matter for debate.

What this person wants is a one-way filter to filter out carbon dioxide, something where CO2 will only go through one direction. No such thing exists as far as I know. Simple mechanisms for capturing CO2 already exist one of the simplest is a lime-water solution which will react with CO2 int he air and then drop out of solution as CaCO3. Magnesium will also do this I think. The CO2 can then be released by heating or treating with acid. I presume carbonates exist on Mars, so only the last part of treating with acid would be needed. Ozone is trickier, it is not stable and breaks down into diatomic oxygen in a matter of hours, so your bag from Neptune would no longer be Ozone by the time you go it to Mars. Ozone can be created from Oxygen using an electrical discharge, but since it does not last very long you have to continually do it in large amounts.

Monomolecular blades

In the first book of Star Trek: The Lost Era, a weapon called a "monomolecular blade" is described. It's a knife or sword whose blade is only one molecule thick. It is described as being able to cut through practically anything - cloth, skin, bone, even solid steel - as if it were cutting through hot butter. Would this work in real life, and if so, why? — JIP | Talk 16:22, 24 October 2005 (UTC)

• It's a staple of science fiction that a molecular monofilament (essentially a wire that was one long molecule) would be able to cut through almost anything since its covalent bonds would be much stronger than the typical Van der Waals or ionic bonds that are the inter-molecular bonds in most things. A blade would be similar. However, I don't know how realistic this is in terms of numbers. --Bob Mellish 17:02, 24 October 2005 (UTC)

We could probably test this, by holding a carbon nanotube. If it falls through the hand, its true. -- Ec5618 19:30, 24 October 2005 (UTC)

If it is one molecule wide and many thick, you would find that in the diction of cutting it may be stiff, but the lateral stiffness of a sheet one molecule thick may be lacking, IMHO. Carbon nanotubes are not one molecule thick. As I recall, bayonets with serrations were especially deadly, to the point that during WWI if you were captured with one, you usually were going to die of your wounds, past or future. Clean cuts are not always as deadly. Dominick ^(ŤαĿĶ) 20:03, 24 October 2005 (UTC)

"Carbon nanotubes are not one molecule thick" I beg to differ. Not only are they one molecule thick, they are one molecule long. Some double walled tubes have been made, which would technically still be a single molecule thick, and long.-- Ec5618 20:26, 24 October 2005 (UTC)

Ripping sound from an mpeg file

So I have an mpeg file and I want to pull the sound from it. Are there any free (gratis or libre) programs for Windows that can do this? I see some from googling, but none that I had any idea whether they were spyware free, which is important. If it matters what type of mpeg encoding, how do I tell which it is.? Related question, does anyone know similar software to rip the sound directly from a DVD? (short bits to qualify for fair use of course). Thanks - Taxman ^Talk 19:14, 24 October 2005 (UTC)

MPlayer (http://www.mplayermq.hu/) and VLC (http://videolan.org/vlc/) are two great open-source media players, and I'm pretty sure both of them have options to dump audio or video to another file. For MPlayer, one of the following command lines should extract the audio from just about any file:

mplayer -ao pcm filename
mplayer -dumpaudio filename

The former will decode the audio to a WAV file, while the latter will just demultiplex it from the video without decoding or altering it. For a DVD, I think you can use dvd://1 as the filename, but there might be additional options. VLC would probably be easier to use, as I believe it has a wizard or something for this, but I can't remember off the top of my head how to do it. Also, if you're on Linux, transcode is an option but I've found it to be a little less robust and more complex than the other two I mentioned. --David Wahler (talk) 19:57, 24 October 2005 (UTC)

Light in a box nr 2

After the 'Light in a box' question above, Eye said I Like this kind of question. Think of another. Well, here's one I thought of as a kid when I learned about those one-way mirrors that are used in police interrogation rooms. If you'd make a sphere (stronger than a box) out of such a material light would build up inside until .... DirkvdM 19:40, 24 October 2005 (UTC)

Actually, such mirrors allow 50% of light to pass through to the other side, whichever side it comes from. So, 50% of incoming light would enter the sphere, 25% would come out the other side, 12,5% would come out the front, after reflecting, 6,25% would go out the back again. Pretty soon, all light would be lost.

Still, the basic premise is the premise behind lasers. A phased wave of light is continually reflected back and forth through a lasing medium. As the photons reflects they persuade energised molecules to transmit a photon, which follows the original photon, and have the same phase and direction. Finally, when enough power will have built up, the energy will be allowed to come out of the lasing medium on either side, creating the beam of light we all know and love. -- Ec5618 20:23, 24 October 2005 (UTC)

Those are partially transparent mirrors. The secret is that the "invisible" side has a lot less light than the other side, so most of this light is reflected and you can't see it, while plenty of light rays from the bright side pass. Light is partially reflected from both sides. So, I think the situation here wouldn't even be interesting, since all light inside the sphere would just go throught its walls eventually. ☢ Ҡieff⌇↯ 20:16, 24 October 2005 (UTC)

A light catcher. I like it. I feel a science fiction story comming on...The evil Lord of Darkness has stolen the Light Catcher because he who controls the light controls the universe....Ha! Ha! (evil laugh):-)--Eye 20:24, 24 October 2005 (UTC)

added after edit conflict:

Nope, sorry. One-way mirrors are actually completely symmetrical; they just appear one-way because the room on one side is much more brightly illuminated than the other. From the brightly lit side, the reflection of the room in the mirror is so much brighter than the light transmitted from the other side that it washes everything out. From the darker side, on the other hand, there's much less reflection and much more transmission. You can test this for yourself; go up to a "mirror" like this and put your eyes up close to it. If you use your hands to block out the ambient light, you'll be able to easily see through the mirror. So in answer to your question: any material that you could use to construct your sphere would let light out just as easily as it would allow it in.

It's actually one of the fundamental theorems of computer graphics that any path will transmit light equally in either direction; I'd give you more information, but I can't for the life of me remember the name of the law. I do remember that there was a relatively recent SIGGRAPH paper demonstrating it in an interesting way—they managed to set up a system where they could use a digital projector as a virtual camera, and vice versa. --David Wahler (talk) 20:24, 24 October 2005 (UTC)

• To clarify, a "one-way" mirror isn't actually "one-way" at all - it must (from thermodynamics arguments) let the same fraction of light go through one way as the other. If you flipped one back-to-front, it would work just the same way. --Bob Mellish 20:25, 24 October 2005 (UTC)

Salt Ice Cream

How does salt lower the temperature of ice in one of those hand cranked ice cream tubs?--Eye 20:04, 24 October 2005 (UTC)

Does it? There are salts that, when allowed to mix or disolve, will react endothermically, causing the temperature to raise. I've heard of those being used to cool icepacks in medical kits, but never for icecream. I believe Ammonium chloride is an example. -- Ec5618 20:23, 24 October 2005 (UTC)

It doesn't. Salty water has a lower freezing point, so you can get liquid water below 0° C. Since liquid takes the shape of its container, this very cold, salty water gets in contact with a larger area than a bunch of ice cubes, so it freezes more efficiently. ☢ Ҡieff⌇↯ 20:19, 24 October 2005 (UTC)

The salt melts the water, since water has a heat of formation, the amount of energy needed to take water from liquid to solid at the same temperature, the energy to do this has to be taken from somewhere, so the temperature of the water lowers.

Spicy Foods

What is the best (fastest) way to get rid of the "hot" feeling in your mouth and/or throat when eating spicy foods such as jalapenos? (Jakz34 21:13, 24 October 2005 (UTC))

I favor eating absorbtive bread, though I think chemical bases like milk are also supposed to be effective. — Lomn | Talk / RfC 21:42, 24 October 2005 (UTC)

• I believe milk works because the spicy-tasting molecules ([[capsaicin]s]) are soluble in fat, but not in water (which is why drinking water doesn't seem to quench the fire). Things like yoghurt also work for the same reason. Though serious curry eaters swear by beer, preferably lager, perhaps because of its well-known topical numbing effect. --Bob Mellish 21:56, 24 October 2005 (UTC)