Wikipedia:Reference desk/Archives/Science/2006 June 5

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bin in /bin stands for 'binaries'?

If /sbin is for 'binaries', why can I put php scripts in there which are ASCII? I would have put this in the elusive computer section if it was properly linked to. Take a look at the top of the page - there's no link to the computer reference desk there. Take a look at the reference desk (one step back in the heirachy) - there's no link to the computer reference desk there. --Username132 (talk) 00:13, 5 June 2006 (UTC)

There is no computer reference desk (at least not one associated with the rest of the "official" reference desks). Computer questions are generally asked here, or on the Misc desk. If they added a "computer" reference desk it would almost certainly be overrun by questions like "How do I edit an article?" and "How come I can't see wikikipadeea? My screan is all blakc!!1"  freshofftheufoΓΛĿЌ  00:45, 5 June 2006 (UTC)

It does indeed stand for binaries. I was mystified by the naming conventions till I read this article. I suspect that there's a more appropriate place to put your scripts (depending on what uses them) than /sbin but regardless of that, you can put anything anywhere - you just might confuse yourself eg making it harder to maintain "good" permissions if you see what I mean.. --The Gold Miner 00:50, 5 June 2006 (UTC)

Because it's "bin" as in "binary executable". With the advent of scripting languages and shells, not all executables are binary, but the "bin" name has stuck. It's really a pretty bad name regardless, since all data on a computer is ultimately binary. --BluePlatypus 01:11, 5 June 2006 (UTC)

sbin is for binaries to be executed by the superuser, i.e. root. bin is for binaries to be executed by anyone. There's also the division into /sbin and /usr/sbin (and similarly for /bin and /usr/bin). The executables in /sbin are those which may be required as the system is booting and before any separate /usr partition is mounted, thus mount must live in either /sbin or /bin.

sbin stands for system binaries. The naming has little to do with permissions. --Swift 07:40, 5 June 2006 (UTC)

php scripts are probably not required before the /usr partition is mounted (or to repair partititions which fail to mount), so /sbin is not an appropriate place for them.-gadfium 01:39, 5 June 2006 (UTC)

Which desk is the computer desk has been the subject of some squabbles recently - it used to be the Science desk, but then someone had a bright idea of trying to 'balance the load' and move computer questions to the math desk (see the descriptions - math is "mathematics and computer science", and science is "science, medicine and technology"). However, many people find it ambiguous, and as a result, computer questions now pop up all over, here, on Math, and even on Misc. — QuantumEleven 22:37, 5 June 2006 (UTC)

Computer Terminals Under Linux

Linux lets multiple users log in at the same time. I've got one computer, two monitors and two keyboards. Is this sufficient to let myself and someone else log in and use the same computer at the same time?

As I understand it, only one monitor and keyboard is typically connected directly to the computer. Any other users would need to log on remotely from another computer. So, no, you would need two computers. Note, however, that the secondary computer could be quite minimal, since you are essentially using it only as a "dumb terminal". Alternatively, both users could log on in different windows on the same computer, but that would require that they take turns. StuRat 02:09, 5 June 2006 (UTC)

Sure it's possible (as long as you've got two graphics cards); it won't be easy though. You'll need to set up your system to start up two DMs with alternate X server configs; you'll need to set the X server configs to use the appropriate video card, keyboard and mouse. EdC 02:34, 5 June 2006 (UTC)

You'd need to configure it to bind each keyboard to a different virtual terminal. By default, all input devices are bound to the same virtual terminal, and the first X session grabs all available input devices. --Serie 20:06, 5 June 2006 (UTC)

As mentioned above, it's possible to do, but unfortunately not a trivial task, and you'll need a good understanding of X. —Pengo 06:22, 6 June 2006 (UTC)

Bird Species

My husband was driving through Belton, MO and saw a bird that he'd never seen before. He came home excited to tell me about it, and it didn't seem familiar to me either. He described it as such: small bird, grey 4-6 inch body, peach colored breast or cheeks. The tail was 12-16 inches long, two feathers, yellow in color with black tips. Any help in this matter would be much appreciated. Thanks a bunch.

Alice and Jesse Montgomery of Belton, MO — Smilingallie 03:04, 5 June 2006 (UTC)

One central North American bird with a gray body and noticeably long tail is the mockingbird [1]. Tail isn't quite a foot long, but I suspect not very many 6 inch birds have tails 2-3 times longer than they are. alteripse 04:55, 5 June 2006 (UTC)

Sounds a lot like a scissor-tailed flycatcher, which by the way is the state bird of Oklahoma. --Ginkgo100 14:10, 5 June 2006 (UTC)

You smarty pants. — The Mac Davis] ⌇☢ ญƛ. 21:41, 5 June 2006 (UTC)

I try. --Ginkgo100 13:59, 6 June 2006 (UTC)

Scissor-tails are probably some of the prettiest birds IMO. Especially when you see them flying, their tail feathers are spiffy.--SeizureDog 06:52, 12 June 2006 (UTC)

DVD/CD-ROM drives in Device Manager

HP DVD Writer 840b and IDE-DVD DROM6216 each have a yellow exclamation mark in Device Manager. Of course, I use the Windows XP operating system. (My drives are internal and were working fine until today.)

The problem is that no disk can be recognized in the CD and DVD players of my computer. Even when I go to My Computer, the drives appear empty. In addition, the Windows Media Player has disappeared from my All Programs menu.

I need help.Patchouli 04:06, 5 June 2006 (UTC)

Check out http://support.dell.com/support/topics/global.aspx/support/dsn/en/document?c=us&cs=19&l=en&s=dhs&dn=1065889

You must follow this steps and you will get your CD ROM back.

Thank you.71.107.224.44 08:56, 6 June 2006 (UTC)

Internet Explorer Shortcut

I want to create a desktop shortcut for Internet Explorer, but I can't because the Internet Explorer has vanished from my All Programs menu of the Start button.

Right-clicking the Internet Explorer shortcut on the Start button doesn't allow me to create a desktop shortcut.Patchouli 04:10, 5 June 2006 (UTC)

Right-click on the desktop and click on Properties, then go to the Desktop tab and click on Customize Desktop. Turn on the Internet Explorer option under Desktop icons. --jh51681 04:36, 5 June 2006 (UTC)

Thank you.71.107.202.21 06:04, 5 June 2006 (UTC)

Natural hair strainghtener ?

Hi, is there anything available in nature which can be used to staighten curly hair ? (I suppose that these products available in nature will have nil or negligible detrimental effect on hair compared to the artificial chemical counterparts?) - Wikicheng 04:20, 5 June 2006 (UTC)

It is fallacy to assume 'natural' means it will have less detrimental effects then 'artificial'. Ever heard of Aflatoxin, Ricin, Uranium and Sassafras tea? All of these are natural occuring... For that matter Tapioca (also known as Cassava) and Cashew nuts are common food items but if not properly prepared, they could easily kill you. Straigthining curly hair is not a simple and personally, I wouldn't do it whether the product used is natural or artificial. Nil Einne 08:07, 5 June 2006 (UTC)

I agree. I was looking for some 'good' things (like aloe vera, henna etc) which will also serve as straighteners - 59.145.142.36 14:12, 5 June 2006 (UTC)

Twine string, rocks... maybe some steam. It all depends on what you consider "natural enough", how far you're willing to go, and what kind of results you're hoping for.  freshofftheufoΓΛĿЌ  06:38, 6 June 2006 (UTC)

Any sort of gluelike or clay-like substance can be used to cement hair fibers together in a straight or curled shape, which returns to its normal shape when the cementing substance is removed (e.g. styling gel, clay). To straighten or to curl an individual hair fiber permanently (see Permanent wave, "reverse wave perm") you need to re-arrange the connection between the side to side strands of hard keratin inside the fiber, which keeps the curly or straight shape of the fiber. To do this you must first degrade or break the disulphide bonds keeping the keratin strands together, using a strong enough alkali. If these bonds are broken the keratin strands fall apart, like a string which has been untwisted so that all the fine strands are frayed apart. The frayed, weak hair fiber then can be curled or straightened as desired, and an acid is now used to reform the disulphide bonds, so that the hair fiber keeps the new configuration of keratin strands. Whether "natural" or "artificial" chemicals are used does not change the fact that damage has to be done to the hair structure to enable the straightening or curling. A laboratory / man-made compound probably gives better control of how strong the chemical is that is used, so I can see no scientific advantage in "natural" products. The oils used to maintain shine and moisture (especially in chemically damaged hair) seem to be a matter of preference, and in my circle of acquaintances different persons seem to respond differently to the same product. --Seejyb 21:36, 7 June 2006 (UTC)

Browser home page problem

Every time I click home on the Standard Buttons of Internet Explorer, I get directed to www.securityuptodate.net a site I never intended to be my home page even though my home page is http://news.yahoo.com/ on the Internet Options menu. I have restarted my computer several times in vain. I have also scanned my computer with Ad-Aware Personal and Norton Antivirus, though to no avail.Patchouli 04:22, 5 June 2006 (UTC)

Hmm, how about searching the registry for the above website address — TheKMan^talk 06:11, 5 June 2006 (UTC)

I edited out the hyperlinks to the site to prevent unwary users from following them, and possibly downloading the software that is there. I have never heard of the site. It could be a site which offers malware as a remedy for malware. If somebody knows something about the site, please update with more info. --vibo56 07:33, 5 June 2006 (UTC)

You've got a virus. Get rid of it and get Firefox. Another great browser, which is speedy, secure and packed with innovative features, is Opera, which I use for editing Wikipedia. --J.L.W.S. The Special One 07:40, 5 June 2006 (UTC)

The site you mention is a spyware-distributing scam. See [2]. –Mysid^(t) 11:30, 5 June 2006 (UTC)

You might also try Spybot - Search & Destroy if you can't find the adware with Ad-Aware. Sum0 13:38, 5 June 2006 (UTC)

• How do I get to registry using menus? I want to know if it is possible to access the registry without entering regedit in the Run window.71.107.224.44 08:53, 6 June 2006 (UTC) Also, how do I search for the Web sites I have visted in the Windows registry? I opened the edit menu, chose Find..., entered www.wikipedia.com, but found nothing.71.107.224.44 09:04, 6 June 2006 (UTC)

This sounds like something I just fixed for a friend of mine. Use the link the User:Mysid provided. Stay out of the registry. Run Firefox instead of IE. Download Avast and run it. --LarryMac 15:59, 6 June 2006 (UTC)

71.107.224.44, regedit is probably the best way to access the registry. There is the console tool reg, but it's harder to use, and doesn't give you any more functionality. Regarding websites visited, you might want to try searching for en.wikipedia.org as opposed to www.wikipedia.com. I'm not sure if IE stores website history in the registry, though. Use Firefox, you really will like it better. It doesn't store any website history in the registry, is spyware-proof, and allows you to clear cache and history a lot easier than IE. -- Daverocks (talk) 07:50, 7 June 2006 (UTC)

Thank you.Patchouli 11:16, 7 June 2006 (UTC)&71.107.224.44

Mouse Question

People attending Disneyworld in Flordia can get their picture taken with Mickey Mouse, but at the same time, supposedly someone in Disneyland in California can get their picture taken with Mickey Mouse. How is this possible without violating the laws of physics? 12.183.203.184 04:25, 5 June 2006 (UTC)

There are at least 2 possible explanations:

• bilocation
• the fact that "Flordia" is a fictitious place so anything that happens there is at best an illusion.

I'm sure there are other less interesting explanations, but I like these 2.  :--) JackofOz 04:39, 5 June 2006 (UTC)

I'm rather disappointed the article doesn't mention the Grand Master of bilocation, Santa Claus. Confusing Manifestation 05:11, 5 June 2006 (UTC)

What is Disney's official explaintion? 12.183.203.184 05:11, 5 June 2006 (UTC)

Who said there is only one Mickey Mouse? I'm sure I could get my photo taken with Bill Gates in Redmond (well if I could convince him) and Bill Gates somewhere else (and we're not even talking about Bill Gates Sr, father of Bill Gates)... Nil Einne 07:57, 5 June 2006 (UTC)

According to special relativity, the notion of absolute time or simultaneity is erroneous—an observer in one frame of reference will measure two events as simultaneous whereas one in another frame will see one event as occurring before the other. (disclaimer: technically true but not the explanation) — Knowledge Seeker দ 08:15, 5 June 2006 (UTC)

Perhaps there is only one Mickey Mouse, but space time is warped around him like a wormhole (or perhaps a mousehole in this case), and the two Mickey Mice are one and the same, but at opposite ends of this wormhole. smurrayinchester^{(User), (Talk)} 11:30, 5 June 2006 (UTC)

An explanation resorting to bilocation is really not necessary. Clearly only one of them is Mickey Mouse and the other is just a guy in a mouse suit. --Ed (Edgar181) 13:25, 5 June 2006 (UTC)

The suspense is killing me, aren't you going to tell us which one is which? Unless… Mickey is a quantum superposition over all the photo opportunity guys. They're all equally likely to be real, until you test one and invalidate your result. Thus, quantum mechanics explains why you always get a guy in a mouse suit if you rip off their heads, but will never kill the rodent. Probably an accidental result of Mickey getting chased by Schrödinger's cat at some point of his career. Femto 14:56, 5 June 2006 (UTC)

:-) Arbitrary username 17:27, 5 June 2006 (UTC)

I think Mickey Mouse is really very large, only he doesn't look like that on the photo. You must surely have seen a photo when someone is leaning at the side of the Leaning Tower of Pisa. Those photos are an illusion, really the guy is much closer to the camera than the tower and he poses in a way that it seems he's pushing the tower hard. More than one people can be photoed in such a way at once. Now it's the same with Mickey Mouse: when you go to Disneyland, your friend just turns the camera towards the giant Mickey that's quite far away, and you stand close to the camera, and than it looks like Mickey Mouse is hugging you. (What I don't understand is how this could work with Disneyland Europe, clearly America is far away from France so you can't see the American Mickey from there.) – b_jonas 15:33, 6 June 2006 (UTC)

Contact lens

Ive heard of designer contact lenses. Would it be possible to make ones that light up or blink, or ones that allow someone to see in the dark?

Ones that light up or blink would require some source of energy, which would be technically difficult to place inside a contact lens. I would think such lenses might also have safety and comfort issues. A contact lens that allows people to see in the dark is extremely unlikely for a very long time to come. --Robert Merkel 07:22, 5 June 2006 (UTC)

The technical challenges of a self-contained power source (or chemical reactants) and a light source thin enough to place within the lens are formidable. Also, even were it possible, the light emanating from the lens would likely interfere with vision, or would be distracting at least, unless the direction of the light could be tightly controlled. I wonder, too, about the long-term effects on vision such a device would have. It would have to use luminescence, and care would have to be taken to avoid excess heat production. Night-vision contact lenses are theoretically possible but are far beyond current technology. — Knowledge Seeker দ 08:42, 5 June 2006 (UTC)

I can't even see any theoretical possibility to construct a night-vision contact lens (unless cameras and displays get really small). Maybe using some wavelength-altering optics, but I don't think there are any. (Well, now that I've read some relevant articles I'd say it would be possible using an image intensifier.) –Mysid^(t) 09:34, 5 June 2006 (UTC)

I know there are some types of lenses with odd colours and designs, like cat's eye, iris like spirals and large all-black lenses like the one that Wes Borland used. So I guess they could make one that glows in the dark with fluorescence or something like that. But they would have to be extra careful to make the fluorescent substance completely contained within the lens, it could lead to nasty allergic reaction in contact with the eye. Not to mention the harm that the very own light emanated from it could cause (or not). VdSV9•♫ 14:37, 5 June 2006 (UTC)

Here's a link to Halloween lenses: [3]. I often see these advertised but have yet to see anyone wearing them - guess I mix with the wrong crowd these days. Rmhermen 15:22, 5 June 2006 (UTC)

If you wear the fluorescent type, then aim some blinking violet LEDs at your eyes, they should light up brightly. The LEDs could be mounted on a hat brim, or on eyeglass frames. --Wjbeaty 05:52, 8 June 2006 (UTC)

Good ole racsism

What causes racism? It seems like this would be a disadvantage with respect to evolution. If there are 4 groups of people, asians, hispanics, black and Whites, it would seem like the most advantagous thing would be to have no racism at all but rather to encourage interaction between the groups--this would allow cooperation (sharing of knowledge etc), increase genetic diversity though mating (allowing advantagous traits from two seperate groups to combine in one offspring. 12.183.203.184 05:10, 5 June 2006 (UTC)

Racism is an extremely complicated phenomena and I would hesitate to say it has a genetic component. However you could claim there is a relationship between racism and Kin selection Nil Einne 07:54, 5 June 2006 (UTC)

I would suggest that there may be some similarities between racism and the instinct to be wary of things which are percieved as different or unusual. There is an obvious evolutionary advantage to being cautious when one encounters new things like rattlesnakes or mountain lions. In situations with limited resources and a might makes right mentality, there would also be advantages to be distructful of foreigners and outside social groups. It is possible that racism is in some minor degree influenced by an instinctual fear of things which are seen as foriegn or different, but it is obvious that any such instinct is entirely surmountable in modern society. Dragons flight 08:24, 5 June 2006 (UTC)

I've noticed many people also see opposite-sex foreigners as more "exotic" and attractive than those of his/her own nationality, and I would say there's a strong genetic component in that—the encouragement to interaction that the questioner is referring to. Also in my understanding, the fear (in this case false) of foreign things contributes to racism to some degree. –Mysid^(t) 09:30, 5 June 2006 (UTC)

The human brain and human behavior are awfully complicated. They are also so heavily influenced by the environment -- and the effects of any gene on them so wide-ranging -- that natural selection doesn't work on them as cleanly as it does on, say, peppered moths. In the case of racism, cultural and environmental influences work on things like fear (a very adaptive thing in itself) and human social behavior (group-forming). --Ginkgo100 14:21, 5 June 2006 (UTC)

I think racism has a great deal of closeness to herd theory and collective hysteria. It has to do with "they are different." Go to any primary or secondary school, and you will find that the kids all make fun of each other. Why? Well, I have my own thoughts on that, but they all are made fun of. Any reason will do that makes them stand out. I was made fun of for being smart (still am). I don't see how that can be bad. But it makes me different from them, and that is why they can call it bad. Friends were made fun of for being tall or short, or skinny, or fat. Same with much of Islam today, and Christianity, Islam and Judaism as well about one-thousand years ago. — The Mac Davis] ⌇☢ ญƛ. 22:18, 5 June 2006 (UTC)

What do you mean by "racism"? If you mean the general "prejudice based on race" definition, try looking at Ingroup bias (preferential treatment of people who "look like you") and Outgroup homogeneity bias (stereotyping). If you mean Institutional racism, that tends to be related to social policy and probably was developed by people in power. --ColourBurst 02:48, 10 June 2006 (UTC)

which is heavier?

Which would be heavier:a bucket of cold water or a bucket of hot water?

Well it would depend on the weight of the bucket and the volume of water. However assuming the weight of bucket and the volume of water is the same, the bucket of cold water would be heavier. Water is most dense at 4°C. See Water#Water_in_biology_and_human_civilization and Density Nil Einne 07:52, 5 June 2006 (UTC)

See also Water_(molecule)#Density_of_water_and_ice. --Swift 07:56, 5 June 2006 (UTC)

There are multiple answers, depending on information that is not given in the question.

If it is the same bucket and water, and not filled to the brim, then the mass and weight has not changed, only the volume.

It is possible that the bucket's volume might shrink more than the water's volume, thus it would hold a smaller mass of water. You would need to know the bucket's material and that material's coefficient of expansion with temperature.

If it is a trick question, the answer is "the bucket with more water in it"

Walt 13:05, 5 June 2006 (UTC)

Assuming the mass of the water is the same, the cold water would be heavier. Cold water will take up less volume than hot water and displace less air than the hot water, so the weight will be a little bit less, but it would probaly take sensitive instruments to make this determination.

You contradicted yourself. If the mass of the water in each bucket is the same, then by definition neither would be heavier. However, if the volume is the same, then the cold water is heavier, but that was already stated above. --Ginkgo100 14:27, 5 June 2006 (UTC)

As someone else has said, the question is not clearly enough defined to give a single authoritative answer to. One of the many ambiguities is whether "heavier" refers to mass or weight. Weight is, properly speaking, the force needed to hold up the bucket, and for this the mass of air displaced is relevant. As a pedantic and somewhat groan-worthy aside, if the intended answer is that the two are the same, then possibly this is overlooking that the hot water will have greater mass due to relativistic effects. Arbitrary username 17:24, 5 June 2006 (UTC)

Concerning heat in phase changes

I've forgotten most the physics I ever knew so this may be badly worded beyond belief but:

When a substance undergoes a phase change from solid -> liquid or liquid -> gas it requires heating and I remember there is a temperature at which for a while heat goes in but the temperature doesn't change. I also remember that there is something called Total Internal Energy, which is K.E + P.E and at each temperature this is constant (unless I remember wrongly). But K.E is also a function of time. So surely all this heat is going in but T.I.E remains constant and so does K.E, meaning that P.E must also remain constant, so where does the heat go? Does it go towards adding disorder to the system? Also, why do molecules not have more K.E as a liquid/gas at this temperature than as a solid/liquid?

 -- Splongul  10:58, 5 June 2006 (UTC)

When you melt something, you are putting in heat energy which is converted into extra kinetic energy on the molecular level. Not all the molecules 'melt' at the same time; as you put the heat energy in, more and more of the solid molecules get enough kinetic energy to 'break free' and become liquid molecules. Once all the molecules are 'liquid', any more heat energy you put in goes to heat the mixture (increasing the potential energy?). So the kinetic energy of the molecules does not stay constant as you heat at the melting point. The same is true as the liquid evaporates. Not sure I answered all your questions, but your instincts were right in questioning the molecules not having more kinetic energy as they melt/evaporate. They do. Skittle 14:36, 5 June 2006 (UTC)

Unless I'm missing something obvious, I'd have thought that in any phase of matter the kinetic energy is going to be just kT/2 in each direction, total 3kT/2, see Boltzmann distribution, and that during melting the heat is going into potential energy (latent heat) not kinetic energy. So what the original question had wrong is the concept that total internal energy is constant at a given temperature; it's usually true but not at a phase transition. But someone please correct me if I'm being thick. Arbitrary username 17:39, 5 June 2006 (UTC)

I'll have a look at these (I don't think I used those equations), but I think the difference is you are looking at the overal substance, I am looking at the individual molecules. But I haven't done this stuff for a while. Skittle 18:03, 5 June 2006 (UTC)

No, by adding heat you're increasing the internal energy. However, the total internal energy is constant with temperature at equillibrium. However, something you're heating is not at equillibrium. --BluePlatypus 23:50, 5 June 2006 (UTC)

Fear of needles

I have a fear of needles that has been bothering me for quite a while. Anyways today I had to take a permisson slip home which would allow my parents to say whether or not I would get a shot for a disease that has been going around our school.(meningitis) Anyway I am literally in tears as I write this because I have a fear of needles and am considering faking my parent's signature because of this fear. please help me! --Devol4 11:52, 5 June 2006 (UTC)

Does your school have a counsellor? Definately talk to this person, if not there are free counselling services available.

Show the permission slip to your parents, and mention that you're afraid of needles and you're not comfortable, and I'm sure they'll know how to help you. Or, talk to someone at your school about it. Hope this helps! Sum0 13:32, 5 June 2006 (UTC)

You're best off getting the shot. If you do catch meningitis, they'll stick a much bigger needle into your spine at the hospital to diagnose you (see Lumbar puncture). I was vaccinated against meningitis myself a few years ago - it didn't hurt at all. The nurse told me to look away and I literally didn't even feel the needle go in... --Kurt Shaped Box 13:37, 5 June 2006 (UTC)

• You don't want to risk catching meningitis. You're better off getting the shot. I would follow the advice the people above gave you - especially that of Kurt shaped box. - Mgm|^(talk) 13:48, 5 June 2006 (UTC)

Sum0 is right.. I'm usually get faint from needles. It's called something, but I forgot. It's cause I get too worked up from the fear of the needle, but the shot for meningitis didn't hurt at all. I'd say it's better to get the shot then get meningitis, especially since its decently contageous. I also suggest counciling if it is that much of an issue. --Chris 14:01, 5 June 2006 (UTC)

In my experience it doesn't help to say you 'won't feel a thing' or such-like, because if the person does feel a thing (I could feel my meningitis shot, although it didn't hurt) they will be less trusting and calm next time, plus they will be shocked at the time. I can tell you that if you tell people how afraid you are, they will do everything in their power to make it a better experience for you. I can tell you that the needle doesn't tend to hurt, and rarely do people feel it. I can tell you that if you fake your parents signature you will most likely get caught and receive the shot under much more stressful circumstances. I can tell you that, as people have said, skipping the shot may result in you needing a much worse needle as well as being very ill.

Tell your parents about your fear, tell your school (whoever is involved in the shot) about your fear, maybe sedate yourself :-) Perhaps tell yourself they only want to inspect your arm, then don't look? I don't know how well you can lie to yourself. Skittle 14:29, 5 June 2006 (UTC)

Yeah, fair point. While my meningitis shot didn't hurt at all, I suppose that some people might feel something, if the nurse is less gentle with the needle for example. I didn't particularly used to like needles, so I told the nurse at the time and she told me to watch the screensaver on her computer. A few seconds later she was like "All done! Let me just get you a sticky plaster" and I was like "You've done it already?". I honestly didn't feel a single thing. :)

Seriously, dude - get it done. The alternative of catching meningitis and getting a long, thick bone needle through your spine (as well as potentially dying) in hospital is much, much scarier. I've never had a lumbar puncture myself but I have had a bone needle inserted into my ankle - yes, it really hurt. Also, I know it sounds really obvious - but pay no attention to the other kids at school and their scare stories of vaccination agony/broken needles/sadistic nurses/etc. They're just shit-stirring.

As an addition - I heartily reccommend getting a tattoo. Once you've been inked, you will never be afraid of needles again... :) --Kurt Shaped Box 16:22, 5 June 2006 (UTC)

A tatoo... probably not the best advice to give to someone who is still in school. I used to be afriad of needles to when i was a child. However, i didn't have an injection for a few years then, as a teenager, i had to have one. I was really worried about it but when it was done, it hardly felt a thing. I then realised that i had built it up in my mind to be much a much bigger thing than it actually was. Since then i have had plenty of injections. While its not something i would say i enjoy, it really doesn't bothere me now. My advice - challenge yourself to do it. I guarantee it will not be as painful as you think it will be. Rockpocket 17:48, 5 June 2006 (UTC)

Trypanophobia. —Keenan Pepper 15:19, 5 June 2006 (UTC)

I get anxiety attacks around needles. The best way for me to cope with it is to tell the person giving you the shot that the needles make you uncomfortable, and that if possible you'd rather just not look at them. Stare in some other direction. Keep talking to them. Eventually they'll give you the shot, it will be a pinch, you will not feel happy, but soon it will be over. But anyway, I'm sure this works out differently for all people, but for me if I don't ever actually see the shot, it's not as big a deal. And if the nurse knows they are usually pretty nice about it. --Fastfission 18:09, 5 June 2006 (UTC)

The funny thing is, for me not seeing the needle is the worst possible thing. I need to see it, and not have my arm restrained, otherwise I feel out of control and panic. Explaining this to a nurse who's been trained, in case of nervous patients, to do it exactly the opposite way can be difficult. Fortunately, now that I know to ask in advance to be allowed to watch, I have gained more confidence about it and thus no longer get so anxious in advance. I can almost pass for someone who isn't scared of needles at all, which of course makes it easier for me to stay in control of the situation, which makes me less scared, et cetera. —Ilmari Karonen (talk) 22:47, 6 June 2006 (UTC)

Yeah, I used to freak right out when I had to get a needle. It was awful; I was really afraid. I found that the best thing for me was to tell the person giving you the shot, so that they can handle you gently. You're not the first frightened person, nor the worst, that they've dealt with. Secondly, don't look. That's what really did me in. I had to look away; most clinics of this type have some sort of poster or something, often mounted somewhere so you're looking away. It's not fun, but it beats the alternative. I always walked away wondering why I'd built it up so much, since it wasn't nearly as bad as it was in my mind. Now, I get needles on a fairly frequent basis, including some I have to do myself, and I have pretty well no fear. --ByeByeBaby 22:44, 5 June 2006 (UTC)

I'll admit, when I was 12, I had not gotten a shot since I was a one-year-old. I was afraid, although I couldn't let my sister down who was only seven, a lot more afraid than I was, and had to get a shot. It does hurt, but less than a pinch by one of your schoolmates, and its worth it because you won't die of meningitis afterwards. You can't feel it going in, just the short acute pain of the puncture, and it is over in less than a second. As far as pain goes, this is near the bottom of the list. However, I don't think you are afraid of the pain are you? Rather the needle itself, and for that, I have no answer. Follow others' guidelines mentioned above. — The Mac Davis] ⌇☢ ญƛ. 23:33, 5 June 2006 (UTC)

\ THANK YOU I GOT THE SHOT THIS MORNING AND IT REALLY WASN"T THAT BAD!! good Bye!--Devol4 11:14, 6 June 2006 (UTC)

Ah great! :D Glad to see we can make a difference. Sum0 22:13, 6 June 2006 (UTC)

More Nucleation Sites than Mentos?

Are there any materials (alumina, calcium carbonate, etc) that would provide more nucleation sites than Mentos, e.g. for the "Mentos/Diet Coke Experiment?"

Thanks!

some kind of activated charcoal? Rmhermen 15:15, 5 June 2006 (UTC)

Fizzies(tm) ? Or just any wettable powder such as powdered sugar, baking soda, etc. I suspect that Mentos work well because they're dense, so they sink to the bottom of the bottle. The bubbles created at the bottom will drive all the cola upwards as a fountain. On the other hand, if you dump some salt into the cola, it just makes fluffy foam at the top, with no big fountain. --Wjbeaty 05:48, 8 June 2006 (UTC)

Black Holes

Does anyone have any authoritative links to what happens to the event horizon when two black holes are in orbit around each other?

Do you know the distinction between apparent horizon and event horizon? If so, try this:

• Miguel Alcubierre, Bernd Bruegmann, Peter Diener, F. Siddhartha Guzman, Ian Hawke, Scott Hawley, Frank Herrmann, Michael Koppitz, Denis Pollney, Edward Seidel, and Jonathan Thornburg (2005). "Dynamical evolution of quasi-circular binary black hole data". Phys. Rev. D. 72: 044004.{{cite journal}}: CS1 maint: multiple names: authors list (link) gr-qc/0411149 See Fig. 5 for apparent horizon and event horizons.

HTH ---CH 17:22, 5 June 2006 (UTC)

There are lots of theorys about control over the event horizon of a black hole. My prime work is on the science of time travel behind black holes, worm holes and einstein-rosen bridges. When a black hole is rotating or otherwise it gives off extream electro magnetic energey. Two black holes orbiting around eachother would cause un imaginable electro magnetic energey decreasing the amount of controle of any sort around the area. User: VictorP

Weird fly identification

I have lots of these weird flies in my garden. I was able to find some photos ([4], [5]) by web searching for "weird fly", but I would love to have a more formal description :). The most striking thing about the flies is the jagged shape of their wings, which if you look closely turns out to be an illusion caused by transparent areas along the wing edge. They also have a noticeably thick proboscis. They are a dull red and about the length of a smallish house fly, but more slender. The photos may be more helpful than my description. Thanks. 128.220.220.95 16:52, 5 June 2006 (UTC)

It might help if you said your garden is near Baltimore, MD (or wherever). ---CH 17:25, 5 June 2006 (UTC)

Good point. My garden is in Baltimore, Maryland. 128.220.220.95 17:28, 5 June 2006 (UTC)

At first, I thought it was a sepsidae (http://mywebpages.comcast.net/tmstuart/Species/Ant-LikeFly5068.jpg), but the wings in your photo appear to be black and white, not clear. Perhaps it is a close relative. --Kainaw ^(talk) 22:43, 5 June 2006 (UTC)

I figured it out: Delphinia picta (Otitidae). Thanks. 128.220.220.95 23:23, 5 June 2006 (UTC)

I just created a page for that guy after seeing it IRL a few times, and not finding anything on wikipedia. The page would really benefit from that great picture of the bubble mating display, if you want to add it. — Preceding unsigned comment added by NessieVL (talk • contribs) 17:12, 19 August 2017 (UTC)

Which freezes faster?

Ok. I have 2 ice cube trays both the same size and both containing the same volume of water but 1 tray contains hot water and 1 tray contains cold water. Which tray of water will freeze faster the hot or the cold. The reason i am asking this is because i have always heard that hot water freezes faster than cold water. To me i dont think that makes any sense.

See Mpemba effect and more at The Straight Dope. –Mysid^(t) 18:35, 5 June 2006 (UTC)

Then what boils faster? Should I fill up pots with cold water from a faucet or hot water? --Chris 18:59, 5 June 2006 (UTC)

According to my experiences in cooking, hot water boils faster. –Mysid^(t) 19:05, 5 June 2006 (UTC)

Hot water if you wan't it to boil faster, bear in mind though that hot water is usually tank stored in the house so contamination may be an issue. Plugwash 19:30, 5 June 2006 (UTC)

For this reason I always take the water cold from the tap, and heat it in a water boiler (more efficient) before pouring into the kettle. –Mysid^(t) 20:05, 5 June 2006 (UTC)

A water boiler? Like, a kettle? d:-? Could you clarify? I thought kettles were efficient boilers of water, that being what they were designed for. If I need to boil water in a pan (for cooking) I'll boil it in the kettle first then pour it into the hot pan. I'm guessing you have some different device in mind to me. Skittle 17:08, 7 June 2006 (UTC)

Like Water-tube boiler? That seems rather industrial and inefficient on a small, batch scale, so I'm guessing not. If your water boiler boils your water, why do you put it in the kettle? Skittle 19:47, 7 June 2006 (UTC)

Hmmm... I do the opposite, I boil water in the (electric) kettle then add it to pots. More energy efficient.--Anchoress 20:03, 7 June 2006 (UTC)

Like me. Please tell us Mysid! I'm dying to know! Skittle 20:34, 7 June 2006 (UTC)

I have no idea of the English term. It looks like a big coffee pot, it is filled with water, electric current is allowed to pass through resistors in the bottom part (some 2,5 kW) and the water heats up very quickly, because the resistor is immersed in the water. In a kettle, the resistor is far below the water and the heat has to radiate or conduct through many layers. (I have this particular model). I put the water back to the kettle because I need to cook potatos or whatever– it's not that practical in a "water boiler" because it shuts down at 100°C. –Mysid^(t) 17:10, 9 June 2006 (UTC)

Ah! It sounds like a particular type of kettle; we used to have one like that, but limescale got annoying. The ones at school had the element in contact with the water too. You cook potatoes in the kettle? I think when you say kettle, you maybe mean what I mean when I say saucepan? This would also explain your comment about 100°C, since electric kettles tend to automatically turn off once the water is boiling. Electric kettle Saucepan Skittle 17:33, 9 June 2006 (UTC)

English kitchen terminology is my weak point. :P Yes, by water boiler I mean an electric kettle. I definitely don't cook potatoes there. When I said kettle in the answer above, I was talking about an ordinary saucepan. –Mysid^(t) 18:35, 9 June 2006 (UTC)

And everything is illuminated! Thanks. Skittle 18:38, 9 June 2006 (UTC)

[Unindenting] Mysid, that's exactly like my kettle (sounds like it anyways). Scaling's no problem where I live because the water's very soft. I actually don't know anyone who uses a stovetop kettle; we all use plug-in ones.--Anchoress 09:59, 11 June 2006 (UTC)

oxbow lake

Could you please tell me how an oxbow lake formation is related to a stream? My son has ask this question from class and I have no answer. Thanks

See oxbow lake. Henry^Flower 19:26, 5 June 2006 (UTC)

Plate tectonics- where is is taking us?

I've seen plenty of maps of the past arrangement of continents - Pangaea and all that - but never one of what the Earth will look like x million years in the future. Do such things exist, or is it impossible to predict? Henry^Flower 19:25, 5 June 2006 (UTC)

Such things exist (see [6]). As to their accuracy, who can say? - Nunh-huh 19:27, 5 June 2006 (UTC)

The atlantic ocean is growing and the pacific ocean is shrinking, just as it has been for millions of year. See Plate tectonics. --Chris 19:31, 5 June 2006 (UTC)

You may also be interested in the Continental Drift Cam. — Knowledge Seeker দ 19:33, 5 June 2006 (UTC)

Thanks for that animation- just what I was looking for. Henry^Flower 20:24, 5 June 2006 (UTC)

You might also like to look at Pangaea Ultima. I'll have to get my partner, the delightful Alice, to have a look at that article... it's one of her specialist subjects and the article's little more than a glorified stub at the moment. Grutness...wha? 03:06, 6 June 2006 (UTC)

See Amasia (continent) for an alternative outcome. -- Avenue 03:24, 6 June 2006 (UTC)

Question about a massive black hole

Does anyone know when Oprah's show starts on XM Satellite Radio? XM 20:06, 5 June 2006 (UTC)

September 2006 ([7], [8]). –Mysid^(t) 20:14, 5 June 2006 (UTC)

I don't understand...Johndoe 111

The archives, science desk

What has happened to the archived questions at the science reference desk? I am unable to retrieve anything that was archived after 20th May 2006 (and yes, I do know how to do a browser refresh). link Is anybody else experiencing this problem? --vibo56 ^talk 20:29, 5 June 2006 (UTC)

Weird. It's like as if May 21st-29th never existed...  freshofftheufoΓΛĿЌ  06:42, 6 June 2006 (UTC)

Looks like the bot has missed it. –Mysid^(t) 06:43, 6 June 2006 (UTC)

I too am missing a discussion. --mboverload@ 22:07, 7 June 2006 (UTC)

• The automated archives from May 21 to May 31 failed (due to archive page size, apparently); see User talk:Cryptic. If you are interested in digging out stuff from those days, it can be done by using the "history" function for Wikipedia:Reference desk/Science. The last version of a day's section was removed 8 days after its date. The easiest way I know to navigate the history is by changing the URL to the appropriate date. -R. S. Shaw 00:36, 12 June 2006 (UTC)

water flow

As water flows downstream, where is the current the fastest? what are the results of the faster current? —Preceding unsigned comment added by 64.12.116.74 (talk • contribs) 20:30, 5 June 2006

The current is fastest in the lower courses of a river, the volume and width and depth also increase as you go downstream, but the gradient of the course decreases. The effects of the current, I'm not sure how you meant it, but you could mean erosion, as the increased current gives the river more erosive power. Particularly as the river meanders, oxbow lakes and so on can be formed. Philc _T^E_C^I 20:52, 5 June 2006 (UTC)

As the size of the river increase and gradient decrease the river current will go slower, not faster. The upper part of many rivers have faster currents, you can't really generalize. Rmhermen 23:16, 5 June 2006 (UTC)

Actually the speed increases, this isn't related to the gradient of the river though. You may have noticed that that little trickle passing down your local hill, is nothing compared to the speed of a larger river, also if the speed decreased as it went further on, the water would be collecting wherever the speed changes, and that certainly isn't possible! Philc _T^E_C^I 13:21, 6 June 2006 (UTC)

The speed can change if the cross-sectional area changes, what is constant is the flow rate. I'm assuming the speed of rivers at different stages is complicated by tributaries increasing the flowrate further downstream, but if the flowrate is constant (ie, no extra streams join or split) then the wider/deeper the river, the slower the flow. Skittle 20:30, 7 June 2006 (UTC)

But extra streams do join, so the flowrate increases aswell surely. Philc _T^E_C^I 21:08, 7 June 2006 (UTC)

But now I understand, taking into account the colective flowrate of all of the tributries the flow rate will remain equal, assuming that the input continues at the same rate, which it doesn't, but that just complicates the point. Yes the flow rate does remain constant but relative to the amount of water in it, the width of the river decreases downstream, despite the fact that on absolute terms it increases, so the waterspeed increases. Philc _T^E_C^I 21:11, 7 June 2006 (UTC)

Okay, what I think your teacher may want is something like thalweg (I hope we have a page on it), the point in a stream where the current is fastest. In a perfectly straight stream, it will be in the middle. As you get closer to the sides, it slows down until it is completely stagnant where it touches the bank. You can test this by dropping leaves/twigs/feathers into a river or stream and watching which go fastest. Once you start involving twists, turns, rocks and rough banks, it gets a little more confusing as various eddies are created. Generally, when the stream bends the fastest current will be found towards the outside of the bend. See meanders and oxbow lakes as recommended by Philc for the effects of this. Also, have you ever seen willows growing by a river? Have you noticed anything about their position? Please clarify if this is not the sort of thing you need. Skittle 08:58, 6 June 2006 (UTC)

Thermometers

Today I visited a clock and barometer restorer, and he mentioned to me that he was having trouble restoring thermometers, either mercury-in-glass thermometers or "alcohol" ones. Being a non-scientist, he asked me if there was a way of calibrating a thermometer that could be worked out just from the internal diameter of the narrow-bore tubing, rather than the trial-and-error approach of putting a whole lot of new thermometers in ice, and then in boiling water, and marking each one individually. He showed me a batch of new items, each of which, he said, were filled with red-dyed xylene. On thinking about this, I considered that there must be a large number of variables, including the volume of the bulb itself. For example, surely the quantity of liquid in the bulb affects the distance travelled by the heated liquid up the tubing? G N Frykman 21:03, 5 June 2006 (UTC)

You're right. The distance the edge of the liquid moves depends on bore diameter and the total volume of liquid whose temperature is changing. The volume of the bulb, which probably has a large fraction of the total liquid volume, is quite relevant. If one has good quality control on the batch of thermometers (bore diameter, bulb volume, amount of liquid at a given temperature) one can calibrate one and then copy onto the others. Depends how accurate one wants the resulting thermometers to be. DMacks 22:44, 5 June 2006 (UTC)

Certainly depends on how accurate you need to be. I had verify, each month, the calibration of already factory-calibrated thermometers against an NIST calibrated thermometer for some industrial work I did. Rmhermen 23:14, 5 June 2006 (UTC)

The vaccuum in the tube matters too, right? --Kainaw ^(talk) 01:31, 6 June 2006 (UTC)

The vaccuum makes hardly any difference for mercury thermometers—liquid mercury is quite dense and virtually completely non-volatile and incompressible. A piffling atmosphere or two of pressure in the tube won't make a measurable difference in the height of the mercury column. (Barometers, of course, are a completely different matter.) On reflection, I expect that dry air shouldn't make a difference to the other types of liquid-in-glass thermometer, either. Water, however, is trouble. It condenses, it vaporises, it freezes. It floats on top of your mercury, sinks to the bottom of your xylene, or might dissolve in your alcohol. It's a nuisance. TenOfAllTrades(talk) 02:14, 6 June 2006 (UTC)

I remember from physics that metals (in particular) have a coefficient of linear expansion. Do liquids have a coefficient of volume expansion? This would surely be a start to trying to work out some sort of mathematical relationship for thermometers? G N Frykman 18:28, 6 June 2006 (UTC)

Gold!!

I've heard that there is more gold in computer chips, per pound, than there is in gold ores. Is this true? --Chris 21:16, 5 June 2006 (UTC)

The best place to find out is probably the companies that "mine" such gold. Can't think of any off hand but at one time did visit a computer salvage yard to find various saleble parts to take to the flee market. The owner was nice but very much the type of person to whom gold was life and vice versa if that helps. ...IMHO (Talk) 23:56, 5 June 2006 (UTC)

When I was in the Marines, there was some guy in another section who clipped the gold leads off all the bad ICs that were tossed out. I was told he had been doing it for years. When he got out, he had a jar of tiny clipped gold wires and got a little over $100 for it. All in all, there's no gold IN the chips. Some chips have gold legs to connect to a board. --Kainaw ^(talk) 00:49, 6 June 2006 (UTC)

Whoa, I'm gonna do that now. — The Mac Davis] ⌇☢ ญƛ. 04:13, 6 June 2006 (UTC)

Keeping in mind there is hardly any gold in gold mines, the days of finding chunks on the surface are gone, mostly a couple of thousand tonnes or something silly of rock, and you'll get a kilo of gold. Philc _T^E_C^I 13:18, 6 June 2006 (UTC)

Medicine (AIDS)

I would like to know whether people suffering from AIDS can be "separated" and "isolated" (as seen in the film Bubble boy for example) so that the patient isn't exposed to opportunistic diseases?Pro bug catcher 21:49, 5 June 2006 (UTC)

That wouldn't be good enough - HIV also destroys the components of the immune system that kill cancer too. Putting someone in a bubble won't prevent that. Also, this question was asked on this page very recently - within the last week. Raul654 21:50, 5 June 2006 (UTC)

Sorry for asking a question that was already asked, and more importantly; thank you very much for your fast and precise answer. Pro bug catcher 22:42, 5 June 2006 (UTC)

It's also a quality of life issue. Would you rather live a normal life for ten years or live in a bubble for twenty years? --Cyde↔Weys 22:54, 5 June 2006 (UTC)

Although this is POV I'd probably chose 5 years outside and 10 inside. One the bright side one could edit all the time. Actually I'm not sure what I'd do except think about it. If I do get AIDS one day I promise to come back and answer you. Thank you again. Pro bug catcher 19:47, 6 June 2006 (UTC)

Global warming controversy

As I understand it, our planet has a very hot molten core and the solid crust we live on is only about 25 miles thick. Could "global warming" be caused by an increase in internal temperature? Also, isn't it possible that our sun is a variable star with a period of about 10,000 years (approximate ice age frequency) and we're just going through a natural cycle? 4.228.246.176 22:59, 5 June 2006 (UTC)charliewalk

I haven't heard anything about the heat inside the earth. I don't see why it should change so much as to affect atmospheric temperatures. See Solar cycle as well. The Sun article might help too. It's one of our Featured Articles. --Chris 23:11, 5 June 2006 (UTC)

Global warming is also featured. Dragons flight 01:47, 6 June 2006 (UTC)

It is possible, and I have heard of it. However, rock is a very efficient heat insulator. Also, remember that global warming is not fact yet, like said on the news everyday. It is still much debated by scientists. — The Mac Davis] ⌇☢ ญƛ. 00:21, 6 June 2006 (UTC)

This is not true. A recent survey of the literature examined almost one thousand peer-reviewed papers published over the last twenty years and did not find a single paper that questioned the fact that global warming is happening and is tied to human activity. Ideogram 06:01, 6 June 2006 (UTC)

Ideogram, do you have a reference for that survey? I would be interested to see it.

As to geothermal heat being the cause of global warming, almost certainly not. See this post for instance. In any case, there is no indication that the amount of heat reaching the surface from underground is increasing; I'm no expert but such a significant increase would probably result in a huge increase in geological activity (as the temperature changes caused heat-induced expansion in rocks). No such increase has been observed to occur as far as I know, and such an increase would attract a lot of publicity. --Robert Merkel 01:35, 6 June 2006 (UTC)

Averaged over the Earth, geothermal heat flow amounts to 0.06 W/m^2. Global warming is associated with changes of a few W/m^2, or in other words 30-50 times the total geothermal flux. The ice age periodicity is 100,000 years, not 10,000 and is believed to be driven by Milankovitch cycles in the Earth's orbit. Our best evidence is that solar activity, while high, has been nearly constant over recent decades while temperatures have continued to climb. See: attribution of recent climate change. Dragons flight 01:47, 6 June 2006 (UTC)

Actually, very large thermal swings (on a 100 million year cycle) are due to the heat in the earth. As well, the carbon and water balance of the earth has changed drastically on that timescale. Compared to those variations, our current little blip just increases the price of cottage property in Canada. --Zeizmic 01:56, 6 June 2006 (UTC)

Volcanism is an important component of the carbon cycle, yes, but the actual geothermal output of the Earth has not been globally significant to climate for billions of years. Dragons flight 07:24, 6 June 2006 (UTC)

How did we figure that out? — The Mac Davis] ⌇☢ ญƛ. 05:00, 6 June 2006 (UTC)

Carbon dioxide levels in the atmosphere are at their highest levels of the last 650,000 years. During that time there have been several Ice Ages where most of the North American continent was under a mile of ice. Ideogram 06:03, 6 June 2006 (UTC)

Thank you very much. Your comments are much appreciated.4.228.246.165 03:05, 7 June 2006 (UTC)charliewalk

Seems unlikely. What would be the reason that the core of the planet would be getting warmer? More likely, the core would be getting cooler, dissipating heat. You'd need to be adding heat sources to increase the temperature. The only heat source I'm aware of that would add heat would be radioactive material, and that would be decreasing due to decay. Unless there were some process causing the radioactive isotopes to congregate, which seems very very unlikely. A more likely possibility would be more heat escaping through the crust (causing the core to cool faster) through volcanic processes, as mentioned above. --Booch 19:47, 12 June 2006 (UTC)

Computer science - Linux

Where is the Wiki for collaborative development of Linux? ...IMHO (Talk) 23:51, 5 June 2006 (UTC)

"Development of Linux" is too general. Are you referring to the kernel, a distribution, a gui, or some Linux software development? All the different aspects have independent teams that, unfortunately, don't coodinate much with each other. So, there isn't one single collaborative development environment. --Kainaw ^(talk) 00:03, 6 June 2006 (UTC)

Unhindered collaborative development of software couldn't possibly work as well as the collaborative development of natural language text, because computer languages are much more sensitive to trivial errors. If Linux were a wiki, it wouldn't even compile 99% of the time. Of course, the source code is freely available, and if you post a patch to the Linux kernel mailing list it's likely to get accepted. I'm proud to say I'm the author of a few lines of Linux kernel code, even though I don't know an interrupt register from a spinlock. —Keenan Pepper 00:04, 6 June 2006 (UTC)

What if code was required to compile and pass regression testing before being checked in? Ideogram 06:05, 6 June 2006 (UTC)

Note that a Wiki for computer programming wouldn't be of general interest and so the users could be limited to a fixed population. Ideogram 06:06, 6 June 2006 (UTC)

One fairly large wiki which documents and answers questions about Linux is at linuxquestions.org. Many Linux distributions also have wikis.-gadfium 00:07, 6 June 2006 (UTC)

Another HIV/AIDS question.

Would it be possible to keep an HIV+ patient alive indefinitely if doctors were to regularly replace his entire blood volume with transfusions of 'clean' blood? If not, why not? This is something I've wondered about ever since I first heard of HIV. I'm aware that replacing the blood would almost certainly leave some virus behind but surely getting a fresh supply of healthy blood every six months or so would help to slow the spread of the virus and prolong life? --Kurt Shaped Box 00:02, 6 June 2006 (UTC)

The big problem is flushing out the original blood without killing the guy in the process. You've also got problems with transplanting an immune system -- blood containing white blood cells from the donor will attack the recipient's body, while blood without white blood cells will will make the immune deficiency from AIDS look mild. --Serie 00:08, 6 June 2006 (UTC)

As noted by Serie, AIDS patients have their immune systems decimated by the virus' action. The presence of HIV in the blood doesn't kill people by itself; it's the way that HIV hijacks circulating immune cells and uses them to crank out new virus that's the problem.

In other words, the component of the blood that most needs topping up are the white blood cells. Unfortunately, these cells – if transplanted/transfused – have a nasty tendency to recognize their new host as 'foreign'. In principle, perhaps you could keep someone alive if you regularly topped them up with white cells from a donor with the same human leukocyte antigen (HLA) type. Unfortunately, HLA typing is much more specific than ABO blood typing, and finding an appropriate matching donor – indeed several matching donors, because you can't just suck one donor dry every month – is very difficult.

It has been suggested that bone marrow transplants could be used to cure HIV infection. The idea is to destroy all of the patient's HIV-infected white blood cells, then replace them with transplanted blood-forming cells from an HLA-matched donor. Unfortunately it is difficult to find matching donors for transplants, the transplant procedure has a non-negligible mortality rate by itself, and HIV has a nasty habit of hiding out in the body anyway—meaning that the new immune system would be rapidly infected and compromised. Back in 1995 there was a trial that involved the use of baboon bone marrow; baboons are resistant to HIV. Since I haven't heard much since, I'm assuming that that strategy didn't pan out, either. TenOfAllTrades(talk) 02:07, 6 June 2006 (UTC)