Wikipedia:Reference desk/Archives/Science/2006 June 6

Electromagnetism
Could electromagnetism be focused into a beam? —The preceding unsigned comment was added by 67.127.166.139 (talk • contribs).


 * You mean like a beam of light? —Keenan Pepper 01:12, 6 June 2006 (UTC)
 * Or a MASER or LASER? If you are asking about magnetism, than not how you would think of it. Ferromagnets can be strategically placed to bend the superior magnetic field how you like. — [[Image:Flag_of_the_United_States.svg|17px]]  The   Mac Davis ] ⌇☢ &#xE0D;&#x19B;. 04:16, 6 June 2006 (UTC)

What distorts the lines of force in all those pictures of the Earth's Magnetoshphere? ...IMHO (Talk) 00:41, 6 June 2006 (UTC)


 * I suppose that solar wind and magnetosphere are linked. --DLL 20:26, 6 June 2006 (UTC)

Book of Tables
I'm looking for a Book of Tables similar to one I have seen published for kids that makes a topic really quick and easy for them to learn. Such books of tables usually start with things like an addition or a multiplication table and expand from there. Whatever will help a kid with attention deficit disorder learn stuff quickly and completely before something triggers his mind to do something else besides learn whatever that particular topic is. ...IMHO (Talk) 00:49, 6 June 2006 (UTC)
 * ¿Tú quiero la mesa? — [[Image:Flag_of_the_United_States.svg|17px]]  The   Mac Davis ] ⌇☢ &#xE0D;&#x19B;. 04:18, 6 June 2006 (UTC)
 * Incorrect grammar. Ideogram 06:12, 6 June 2006 (UTC)

mmm... fava beans
so i buy some fresh, in-the-pod favas at the market, take them all out of their husky pods, and then blanch, for thirty or so second, the actual beans in boiling water to loosen the tough skins and make them easier to pull off. when i remove the favas from the boiling water, the water has been lightly dyed light green by the beans. i leave it and go on to peel all the beans. about a half hour later, i go to clean the pot, which is copper on the outside and either steel or aluminum (i'm pretty sure stainless steel) on the inside. the water the beans were blanched in had turned light red. how? the peas are green. the water was green when i removed them. what reaction happend to make this occur? it was really cool


 * Possibly an Fe(II) Fe(III), porphyrin ligand substitution from green (Mg(II)) (i.e. the porphyrin part of chlorophyll) to red (Fe) (i.e. the Haem part of haemoglobin)... The question is, are the beans rich in Iron? --Eh-Steve 04:05, 6 June 2006 (UTC)

1 cup gives 11% of your daily iron requirement (is that nutrition label number a requirement?). would that be enough?


 * If thats true then they are extremely rich in iron, so the reason I gave is very likely. --Eh-Steve 13:18, 6 June 2006 (UTC)

why should i or should i not go with linux?
is microsoft's grip on the software world too tight for linux to be a good idea? is the new windows coming out a bad idea too?


 * I say go for Linux, but then again I'm a crazy Linux zealot. See Operating system advocacy. —Keenan Pepper 01:16, 6 June 2006 (UTC)


 * Hmm, maybe I should take up painting... — [[Image:Flag_of_the_United_States.svg|17px]]  The   Mac Davis ] ⌇☢ &#xE0D;&#x19B;. 04:24, 6 June 2006 (UTC)

why? feel free to advocate if you so desire


 * I haven't used Windows on any of my comptuers since 1995. But, I'm a software engineer and I manage many Unix/Linux servers.  It is easier to work with Unix/Linux with a Linux PC than it is to do it with a Windows PC.  Also, all my computers NFS mount each other to the same directories so it is like I have one big filesystem that follows me from one computer to the other - no messing around with uploading/downloading files all the time.  Note: I do not play games, so I could care less how much better Windows is at games. --Kainaw (talk) 01:30, 6 June 2006 (UTC)

ok, but am i screwing myself over if i switch from windows to linux? what happens to all the windows-friendly programs i'm used to. all the adobes. all the media players. all the little things i've gotten over time that if i switch over might (?) get lost along the way. doesn't microsoft make sure that all these programs work only with windows? any way to get around this? is that mac os the best bet?
 * Personally, I use both (Windows at home, Linux at work). I went through an enormous number of linux distros before I found one I liked enough to use consistently (roughly in order: Slackware, Debian, Mandrake, Redhat, Redhat, Fedora Core, Ubuntu). Without a doubt, my #1 pet peeve is that most linux distros make installing software horribly frustrating. (I won't go into details, but trust me, I'd much rather be using software than manually installing every recursive dependency). Debian and Ubuntu are the exception - they make it extraordinarily easy. As such, if you are going to try one, I *STRONGLY* recommend Ubuntu. Raul654 02:28, 6 June 2006 (UTC)
 * Up until recently, I would strongly disagree that Debian is easy to install. Probably the most frustrating for the beginner is Slackware or Gentoo, IMO. As for Windows programs, there aren't too many that don't have equal (or superior) Linux equivalents. The notable exception is in the games department, but you can emulate Windows to run those. Starcraft in particular plays beautifully. Isopropyl 03:47, 6 June 2006 (UTC)
 * I think you are being a bit generous to put Gimp and Photoshop on the same level. Raul654 03:52, 6 June 2006 (UTC)
 * I never said that the GIMP is on par with Photoshop. Isopropyl 04:08, 6 June 2006 (UTC)
 * Have you thought about duel booting your machine. That is partitioning, or separating your hard drive into sections, and installing linux on one partition while maintaining your windows os on the other partition. This would allow you to keep all the stuff you like about windows, and see if you can do the same on your linux side. Once you feel comfortable, you can make the complete switch. If you are just using the computer for surfing the internet, playing music then any Linux distribution probably comes with firefox, a program you alread know, and xmms, a music player styled off winamp. If you want to learn about system administering, or want to do programing (not that you have to use linux to program) then again Linux. But, if you want to play high quality video games, Word Processing, or want to use the majority of the comercial software then use Windows. It all depends on what you are doing, which is one of the reasons I choose to duel boot my machines. Hope that was somewhat informative. --Linux advocate
 * OpenOffice does word processing very nicely. Isopropyl 04:08, 6 June 2006 (UTC)
 * Windows Vista is going to be a lot more like Mac OS X in look and feel... it may not cause suffering anymore. But then again I'm a crazy Apple zealot. — [[Image:Flag_of_the_United_States.svg|17px]]  The   Mac Davis ] ⌇☢ &#xE0D;&#x19B;. 04:12, 6 June 2006 (UTC)


 * Do not base decisions on Microsoft's future products. When considering choices, Windows Vista does not exist. You don't know when it will come out. Microsoft are notorious for promising more than they can deliver and promising it sooner than they can deliver. Not to mention having plenty of bugs in new versions of operating systems.


 * Onto Linux. Linux zealots will tell you that Linux is as easy to use as Windows and has can do everything Windows can do and more. This is true. However be prepared to sweat a little getting things set up and working. Expect some hardware to be difficult or impossible to get going due to proprietary-only drivers (which shows that Windows does have a too-tight grip, as you mention). And expect to get frustrated and for some things not be how you'd like them (as is the case with any software learning experience). Also expect some things to "just work" that you never before considered could exist. You can set up a dual boot system so you can "fall back" to Windows when you need some old software or need to get something done in a hurry (Things will take longer at first). First and foremost, Linux is a learning experience.


 * One of the best things about Linux is the free and open source software that runs on it, including Open Office, GNU Image Manipulation Program, Inkscape, Eclipse, and of course Firefox. All these things are also available on Windows, but how can Linux be a bad idea? —Pengo 06:17, 6 June 2006 (UTC) (running Ubuntu)


 * You do realize how much of a non-sequitur the above statement is, don't you? There are lots of ways running Linux can be a bad idea, depending on the user and what they need to run with it, if you are talking about a practical question. If you are talking about an ideological question, that's another thing alltogether, but even then one could imagine rationales against Linux. --Fastfission 14:41, 6 June 2006 (UTC)


 * I would definitely recommend trying a Linux machine before switching completely. Some of the commercial software you mention have pretty good open source alternatives. (I've actually taken to preferring Inkscape over Illustrator because it does certain things a lot better and more intuitively.) But some of them are not yet adequate (OpenOffice.org Base, for example, is still light years behind Microsoft Access. I don't hold it against them, and I hope they catch up, but until it is closer, I can't possibly substitute it.) --Fastfission 14:45, 6 June 2006 (UTC)
 * Inkscape is great; OpenOffice is terrible - unbearable slow. Raul654 16:14, 6 June 2006 (UTC)


 * Ubuntu linux is the best for new users --Masatran 16:11, 6 June 2006 (UTC)


 * I find blind Linux love is not always a great idea. I used to idolise Linux, until I actually tried Mandrake Linux and ran into a whole host of show-stopping problems that required reinstalling the OS several times. In the bad old days of Windows 98, Linux was a good alternative: but Windows XP is actually - shock horror - quite a good OS. Don't get me wrong, there's nothing particularly wrong with Linux, but then there's nothing wrong with Windows either. Well, that's a lie, but crawling around in /dev/ or /lib/ or whatever it's called with a torch manually editing some godforsaken config file is no fun. Sum0 22:09, 6 June 2006 (UTC)


 * But making sounds in one line of code is: my friend and I had great fun exploring the sounds one could make with one-line bash scripts with redirects to /dev/audio (or /dev/sound or /dev/dsp). cat /dev/urandom > /dev/audio and yes | /dev/audio are good starts. So having a /dev directory can be fun, if that's your thing. --대조 | Talk 23:08, 6 June 2006 (UTC)


 * Who in their right mind would want to go crawling around in /dev or /lib (actually, he probably meant /etc) with a torch when you can go crawling around in the registry with a torch!? --Kainaw (talk) 15:02, 7 June 2006 (UTC)

Mind-body transfer organization?
I was wondering if there were any organizations in existance that are working toward whole-body transplants or some form of mind transfer. I'm aware of the Immortality Institute, but they don't seem as aggressive as I'd really like. I'm also aware of the Raëlian Movement, but I'd like something a little less religious. - Laharl 02:05, 6 June 2006 (UTC)
 * They won't get there anytime soon. — [[Image:Flag_of_the_United_States.svg|17px]]  The   Mac Davis ] ⌇☢ &#xE0D;&#x19B;. 04:07, 6 June 2006 (UTC)


 * Not exactly what you asked for, but check out US patent #4,666,425. —Keenan Pepper 05:40, 6 June 2006 (UTC)


 * Looking at the Immortality Institute: they could fullfil their mission statement simply by encouraging everyone to suicide. You could have yourself frozen until research advances far enough, but it'll be expensive. On the other hand, all of these procedures will likely be expensive with no guarantee (or likeihood) of success. The cheapest way of surviving 'til then would probably be like Methusulah's Children; a bred-for trait. Alternatively, if you're trying to stay alive and mobile, robotics is probably the area to look into. Vast progress has been made already when it comes to limbs, and more will be made. Artificial eyes and hearts look promising, with other organs beckoning too. You could take the cyberman approach and gradual upgrade yourself. Skittle 14:20, 6 June 2006 (UTC)


 * A pretty pointless pursuit, we don't even know how the brain works. --mboverload @ 22:05, 7 June 2006 (UTC)
 * Consider minduploading.org. Especially http://minduploading.org/mu-faq.html#faq0, regarding the previous point. Don't really need to know how the brain works, just now the neurons work (which is something we know quite well). In fact, we know quite a bit about how the brain as a whole works, so that's not quite a correct claim.128.197.81.181 22:31, 7 June 2006 (UTC)

Expansion of Water by Freezing
Generally speaking, from what I understand, a compound such as water, or any other for that matter, can exist in three different forms: Gas, liquid and solid (let's leave aside plasma for now, it's not relevant to the question and besides, it's well beyond my limited knowledge of science!)

Let's take water as an example. (Under standard pressure) above 100C it exists as a gas (water vapour), between 0 and 100C it exists as a liquid (water), and below 0C it exists as a solid (ice). As the temperature is lowered from above 100C to below 100C, a given mass of water vapour is condensed into liquid water, and in turn volume decreases and density increases. If you further cool it to below 0C, the liquid water freezes into ice, and, one would expect, it's volume should further decrease and its density should further increase.

Yet that doesn't seem to happen. Liquid water seems to actually expand in volume when it's frozen. Shouldn't it be contracting? Why does water actually seem to increase in volume and decrease in density when the opposite should be happening? Thanks! Loomis51 03:00, 6 June 2006 (UTC)


 * This is because of the crystal structure that water forms when freezing. If you cool ice enough (much past the initial freezing point) it actually becomes denser than water just before freezing Mayor Westfall 03:17, 6 June 2006 (UTC)
 * This is actually incorrect. Ice is less dense than liquid water at all temperatures, despite a slight increase in density. Also, be aware that the melting and boiling points vary with pressure. See ice (particularly the phases), melting point, boiling point, and for kicks, triple point. Isopropyl 03:35, 6 June 2006 (UTC)
 * Several types of Amorphous ice have greater densities than liquid water. However crystalline ices (all thirteen forms) when freeze, form crystals, and much empty space is is formed between the crystals. An explanation from the article, ice: This is due to hydrogen bonds forming between the water molecules, which line up molecules less efficiently (in terms of volume) when water is frozen. The result of this is that ice floats on liquid water, an important factor in Earth's climate. Density of ice increases slightly with decreasing temperature (density of ice at -180 °C (93 K) is 0.9340 g/cm³). — [[Image:Flag_of_the_United_States.svg|17px]]  The </tt>  <font color=#006600>Mac Davis ] ⌇☢ &#xE0D;&#x19B;. 04:01, 6 June 2006 (UTC)
 * Also water (in liquid form) is heaviest at 4°C (if I remeber correctly), water does not get heavier and heavier when cooling from 100°C to 0°C, it gets heavier down to 4°C then lighter again! Why? Stefan 04:16, 6 June 2006 (UTC)
 * Again, because the gas form has a lower density than the liquid, and because the frozen form has a lower density than the liquid. — [[Image:Flag_of_the_United_States.svg|17px]] <tt> The </tt>  <font color=#006600>Mac Davis ] ⌇☢ &#xE0D;&#x19B;. 04:28, 6 June 2006 (UTC)
 * See Water_%28molecule%29, "Generally, water expands when it freezes because of its molecular structure, in tandem with the unusual elasticity of the hydrogen bond and the particular lowest energy hexagonal crystal conformation that it adopts under standard conditions. That is, when water cools, it tries to stack in a crystalline lattice configuration that stretches the rotational and vibrational components of the bond, so that the effect is that each molecule of water is pushed further from each of its neighboring molecules. This effectively reduces the density ρ of water when ice is formed under standard conditions." and "Nevertheless, the unusual expansion of freezing water (in ordinary natural settings in relevant biological systems), due to the hydrogen bond, from 4 °C above freezing to the freezing point offers an important advantage for freshwater life in winter. Water chilled at the surface becomes denser and sinks, forming convection currents that cool the whole water body, but when the temperature of the lake water reaches 4 °C, water on the surface, as it chills further, becomes less dense, and stays as a surface layer which eventually freezes and forms ice. Since downward convection of colder water is blocked by the density change, any large body of fresh water frozen in winter will have the coldest water near the surface, away from the riverbed or lakebed. This accounts for various little known phenomenon of ice characteristics as they relate to ice in lakes and "ice falling out of lakes" as described by early 20th century scientist Horatio D. Craft." Stefan 04:25, 6 June 2006 (UTC)

Just wondering Stefan, are you by any chance an engineer? Loomis51 10:33, 9 June 2006 (UTC)

Ubuntu
Ok, so what should I do? I previously downloaded the.. uhm.. thing that you can run the system off a cd. I burned it on a cd, but I couldn't figure out how to get it to work. Should I do that? Should I do it the other way? — <tt> The </tt>  <font color=#006600>Mac Davis ] ⌇☢ &#xE0D;&#x19B;. 05:22, 6 June 2006 (UTC)
 * Presumably, you're talking about a Live CD, which can boot the operating system without modifying the hard drive.
 * To get it to work, you need to restart the computer with the CD in the drive. Depending on how your computer is configured, (1) it might say that it has detected a bootable CD and you need to press a key to boot it, or (2) it might go straight to your already-installed operating system (which means you probably need to change the bios - done by pressing delete/F8/etc when the computer starts - to try to boot the CD drive before it tries to boot the hard drive). Raul654 05:29, 6 June 2006 (UTC)
 * Well, now I deleted it off of my main computer, and the unlabled cd has been lost. Should I download it again? — [[Image:Flag_of_the_United_States.svg|17px]] <tt> The </tt>  <font color=#006600>Mac Davis ] ⌇☢ &#xE0D;&#x19B;. 05:46, 6 June 2006 (UTC)

Also, why should I use Ubuntu? What makes it better aside from it looking better? I will be doing some hardcore university-style schooling in a few weeks, and need maximum productivity. Do you get a lot of problems? No, I don't mean problems you can fix easily, I ask do you get a lot of problems? Does it ask you a lot of questions, do you need any antivirus or anti-spyware things? What is the list of essential programs I need, and where do I get them? I am kind of a normal guy that knows nothing about networks, but is pretty good with software. Is AIM or a client available for Ubuntu? Where do I find all the amazing programs? What is this about ? Thanks, Yours Truly, <tt> The </tt>  <font color=#006600>Mac Davis ] ⌇☢ &#xE0D;&#x19B;. 06:19, 6 June 2006 (UTC)
 * To answer your questions: Ubuntu is a nice clear polished distro that is easy to use and install and has regular updates. Yes you will have problems, especially with odd hardware and setting up media players, and possibly with partitioning your drive and setting up a proper video driver, although the default will work fine. No it doesn't ask you many questions. You do not need antivirus/spyware as viruses and spyware are generally lacking on Linux. Ubuntu includes a lot of software and includes an updater for downloading more. There's also plenty of other repositories you can find by reading Ubuntu's FAQ and searching google. Several AIM clients are available including Gaim, which comes with Ubuntu. —Pengo 06:50, 6 June 2006 (UTC)
 * Ooh, a chance to do some Ubuntu-advocacy, yay! Right, now then: I've used Ubuntu for nearly a year.  It started good and has improved immeasurably.  I guess I would say that running Linux is a bit of a "journey" - with Windows you have problems but can't do anything about them whereas with Linux you have problems but can solve them.  This means that you do a lot more "fiddling" than you would with Windows but there's nothing necessarily wrong with that and you end up with something better.  I don't know what your university work is but if it currently relies on MS Office / the internet you won't have any problems, though I would recommmend investigating whether your printer is supported if necessary.
 * The "components" and the rationale behind them won't really affect you as a user. You'll probably want to opt in to all of the components and this is simple. Where do you get software?  Well, Ubuntu has a fantastic system to deal with this.  The basic idea with it is that your system knows at all times what software you have and so if you have a situation where, for example, a certain application depends on another to run, your computer will deal with it for you and keep everything nice and organised. In practice you'll probably hear about a bit of software on the internet, for example on sourceforge but then you'll go to your system to see if it knows about it.  9 times out of 10 it will.  My system, for example, knows about 19,000 packages.  This, in my opinion, is Ubuntu's greatest selling point.
 * So much to say! I guess I'll also put in my "things I wish someone had told me about *nix OSes a year ago":  1) "~" is shorthand for your home (it's embarassing how long it took me to figure that out). 2) files and directories prefixed with a dot are in most cases hidden from you. 3) man pages are the best thing since sliced bread. 4) Respect your system's desire to keep you away from system admin most of the time - it's a good thing.  5) There is a logic behind the directory structure. 6) Use vi, not Emacs.  That last one probably counts as opinion rather than advice.
 * So much more to say still! I won't go on forever, so, briefly, the single best thing about Ubuntu is this:  if you have a problem, however esoteric you think it is, you can bet that someone far older and wiser has had it already and, in most cases, solved it and written about it. Good luck. --The Gold Miner 09:31, 6 June 2006 (UTC)
 * Nano forever! —Keenan Pepper 15:10, 6 June 2006 (UTC)
 * PS (!) In answer to "do you get a lot of problems" actually (despite all the above) with the latest Ubuntu my experience is no, you don't have many at all. A lot of this will depend on hardware but you'll be able to tell pretty quickly if you're going to have major problems.  Anyway, good luck.  --The Gold Miner 09:41, 6 June 2006 (UTC)
 * Although I strongly appreciate open source software, I'm primarily a Linux user because I'm an old-school Unix user. Mac Davis: as I understand it you are already a Mac user, and I presume that's Mac OS X. You already have a good Unix environment. There's little point in changing to Linux unless there's specific software you want to run which hasn't been ported to Mac OS X yet. I don't have any significant Mac experience, but you might want to explore the Mac command line a bit if you want to get more power out of your Mac. If that doesn't appeal to you, then Linux probably won't either. To others: you can run Linux these days without using the command line, but you'll miss much of the power of the operating system. Don't let me put you off running Linux, just because my habits were formed 20 years ago.-gadfium 09:55, 6 June 2006 (UTC)


 * Sorry Mac, I guess my comments were more directed to a Windows user to whom (it seems to me) the advantages of Ubuntu are many and obvious. I got Linux when I bought I new computer and was faced with choice of 1) buying Windows with no guarantee it would install or work 2) pirating Windows with slighty less chance 3) taking a shot on something free and legal.  For me it was a no-brainer.  OS X wasn't an option because of price. However, my housemate recently got a shiny new Apple laptop and it's so so lovely and I'm not sure why you'd want to change unless you're buying a new system. Gadfium's spot on with what he says above.  If you find yourself fiddling with the command line for fiddling's sake then maybe Linux has something that can tempt you since there's plenty more fiddling to be had, but if not, well: if it's not broke, don't fix it.  --The Gold Miner 11:43, 6 June 2006 (UTC)

For Linux, you have to get 'under the hood' a lot more often than some people would like. I use it extensively for multimedia, and showing stuff on the big screen, without using horrible dvd's. The Mac comes with many things included, but still lives on proprietary software. Linux is terrible for printer drivers, and if you have 64-bit Linux like I do (great for video!), then it is even more hopeless. --Zeizmic 12:46, 6 June 2006 (UTC)
 * Thank you very much everybody for your thick replies! I am planning on trying Linux on my currently Windows laptop. I'll be taking the laptop to Northwestern University in a few weeks. What is this about printers? Although at home I almost never print from the lappy, I can't have printer trouble this summer. — [[Image:Flag_of_the_United_States.svg|17px]] <tt> The </tt>  <font color=#006600>Mac Davis ] ⌇☢ &#xE0D;&#x19B;. 22:25, 6 June 2006 (UTC)
 * You'll want to look at this list for printer info, I should think. Check it even if you're buying a new printer - don't trust "Linux CD included" advice from manufacturers - it's not necessarily that simple.  --The Gold Miner 23:02, 6 June 2006 (UTC)

wierd colors and patterns
when i rub my eyes i can see different colors and sometimes patterns.is there a specific name for this phenomenon??why does it occur?


 * Phosphene seems to be what it's called. The article could do with a little improvement, and maybe interlinking. Hope it helps. Skittle 10:17, 6 June 2006 (UTC)
 * Yeah, you're rubbing your eyes too hard man. Hard enough to cause mechanical stimulation of the retina. — [[Image:Flag_of_the_United_States.svg|17px]] <tt> The </tt>  <font color=#006600>Mac Davis ] ⌇☢ &#xE0D;&#x19B;. 22:35, 6 June 2006 (UTC)

Headache during flying
Hello everyone. While sojourning back from a brief holiday to Wroclaw, when the plane started descending, I suddenly got a blinding pain just above my left eye, which seemed to come from just behind my forehead. I suffer from migraines occasionally, but this wasn't a migraine (wrong location, different kind of pain), and was, if anything,m more painful. I've only ever had this once before, and it was again when a flight was descending (curiously, the only two times I've ever flown with Ryanair ...). I'd been chewing, and drinking water, because I don't like it when the pressure makes your ears go all weird (is there a word for this?), and my ears seemed fine, no popping or anything. I've flown plenty of other times with no problems.

It's 24 hours later now, and there is still a very tender spot above my left eye, but no visible marks. I checked out decompression sickness, but that only ever seems to be in ascending, non-pressurised aircraft. Anyone know what could have caused this pain? <font color="#007700">Proto <font color="#555555">||   <font color="#007700">type   10:18, 6 June 2006 (UTC)

Aha, a bit of further investigation shows it could have be aerosinusitis, in my frontal sinus. But I'm no doctor. Anyone have any ideas how I can avoid this ever happening again (or a better idea of what it might be, as the aerosinusitis is a whole three lines long)? <font color="#007700">Proto <font color="#555555">||   <font color="#007700">type   10:22, 6 June 2006 (UTC)
 * Any plugged sinus will cause you problems in flight. You have to learn to tell if your sinuses are clear.  A good dose of Allegra-D or other such medicine may be called for.  Persistent plugged sinuses call for a trip to the doctor. --Zeizmic 12:02, 6 June 2006 (UTC)
 * It might be an icepick headache. It's not a migraine, but many migraine sufferers get them. You should still go to the doctor though.--Anchoress 12:33, 6 June 2006 (UTC)


 * IANAD but I believe usual NHS advice (according to my phone book) for a sudden, blinding headache is to get medical attention immediately, especially if it is accompanied by loss of strength or feeling in any limbs, as bad things may be happening to blood vessels in the brain. If it has left an ache, doesn't this suggest it has actually done something? I'd get it checked out ASAP. Skittle 14:06, 6 June 2006 (UTC)

Control Systems
Imagine a windmill with two blades of same moment of inertia rotated form the center.Guess it would not vibrate at any angular frequency,and i guess it would have its own distinct net moment of inertia value.But remove one blade,and then,guess only the moment of inertia value would change(i guess).And rotating this system about the center would be unstable(seems).But any idea how would the equations for stability in nyquist or laplace domain change? Is it that objects rotated with center of gravity passing through axis of rotation tend to be stable?

Fuel cell
In the working of the fuel cell,Hydrogen diffuses into the polymer membrane forming protons and electrons.How is that possible in a solid polymer,If it does so in water its comprehendable.


 * Pardon the maths formatting:

It doesn't diffuse. The polymer is a Poly-fluorinated sulphonic acid ($$ CF_3 {(CF_2)}_n SO_3 H $$ ) which dissociates into $$ H^+ $$ and $$ CF_3 {(CF_2)}_n SO_3 ^- $$

This means the solid acid has released H+ ions and is now free to accept them. The anode converts $$ H_2 $$ to $$ H^+ $$ and $$ 2e^- $$. The 2 electrons make their way around the circuit, and the $$ H^+ $$ ions can react with the $$ CF_3 {(CF_2)}_n SO_3 ^- $$ and enter the solid. However, the reverse can happen on the other side, so as $$ H^+ $$ ions enter one side, they leave the other, in effect, producing a "proton filter" allowing nothing else to pass. Repost if the explanation was unclear or too complicated --Eh-Steve 13:57, 6 June 2006 (UTC)


 * The article you're looking for is proton exchange membrane or proton conductor. —Keenan Pepper 14:05, 6 June 2006 (UTC)

camphor
"How to make camphor burn without smoking. What are the things to be added to camphor so that it does not smoke while burning."


 * This is indeed an incomplete statement, what would you like us to do with it? <font color="Green">Philc TECI 17:05, 6 June 2006 (UTC)
 * I imagine the question is exactly what it says: "What are the things to be added to camphor so that it does not smoke while burning?" I'm curious too; does anyone have an idea? The camphor article could stand some improvement, perhaps by an Indian editor familiar with the ritual use of the stuff. --jpgordon&#8711;&#8710;&#8711;&#8710; 19:03, 6 June 2006 (UTC)

Do birds have sensation in their beaks?
If you tap on your pet bird's beak with your finger, can he feel anything - or is it just like tapping on bone?
 * No nerve cells go through the hard parts of any creature, so it is like tapping on your tooth, or touching your hair. --Zeizmic 12:50, 6 June 2006 (UTC)
 * From beak: The outside surface of the beak is covered by a thin horny sheath of keratin called the rhamphotheca. Between the hard outer layer and the bone is a vascular layer containing blood vessels and nerve-endings. In my experience, birds' beaks are very sensitve, although the rhamphotheca itself does not contain nerve endings. In that way, it is indeed like tapping a tooth (which I can definitely feel, although the enamel contains no nerve endings). --Ginkgo100 14:22, 6 June 2006 (UTC)

balance disorder (vertigo Problem)
''I am moving the following question, submitted by Prashant halve, to here from its original location at Wikipedia talk:Requested articles/music. --Lph 13:34, 6 June 2006 (UTC)'' Please suggest My Mother is suffering form position vertigo problem (balance disorder) in that her brain continuously blink so she not able to do any work. all positive treatement and test wood be done but no releafe.If have u any treatement for that please suggest


 * There may be some helpful information at Balance disorder. --Lph 14:43, 6 June 2006 (UTC)

Internet Explorer Script Error
I have downloaded the Answers Toolbar. It allows me to Alt-Click on any word in any program on my screen for a pop-up window with a concise AnswerTip. However, every time I so do I get an error pop-up.

<font style="color:red">Internet Explorer Script Error /!\ An error has occurred in the script on this page. Line: 9 Char: 15 Error: 'undefined' is null or not an object Code: 0 URL: http://www.answers.com/main/tip2.jsp?s=desk/Science Do you want to continue? Yes, No

I get this pop-up on any word I click on. I have had this problem since yesterday. I have a Windows XP. I have gone to Internet Options on the Tools menu and set to security options to their default settings. I have tweaked the other options on the Advanced tab. I have updated Windows XP and restarted my computer, too. Nothing solves this problem. Can someone help?Patchouli 15:12, 6 June 2006 (UTC)


 * What version of Internet Explorer are you using? --Kainaw (talk) 19:12, 6 June 2006 (UTC)
 * <Insert derogative "IE is t3h SUXX! Get Firefox" comment here> -Benbread 19:26, 6 June 2006 (UTC)

My friend says that Firefox runs well only for about a month, after which you have to purchase the browser.Patchouli 03:10, 7 June 2006 (UTC)


 * Your friend doesn't know what he's talking about. Mozilla Firefox is free software, no purchase necessary. I have been using it for years with no problems. -- Avenue 04:11, 7 June 2006 (UTC)


 * I use version 6.0.2900.2180.xpsp_sp2_gdr.050301-1519Patchouli 03:10, 7 June 2006 (UTC)


 * I don't know what I did, but, all of a sudden, the problem has gone away.Patchouli 03:14, 7 June 2006 (UTC)


 * Weird, because you probably didn't do anything. The error you are getting is an error IE encountered while trying to run the script that answers.com wrote; it's not really your fault. It sounds like they're trying to use the undefined object in their scripts, but instead of using it properly, they're trying to use it as the name of a variable or something similar. You can turn off JavaScript debugging alerts in IE anyway, under the Advanced tab under Tools -> Options. By the way, use Firefox. :P -- Daverocks (talk) 07:16, 10 June 2006 (UTC)

IQ
How can we increase our IQ? Thanks
 * While there's some debate over the effects of genetics versus environment on IQ scores, there're any number of factors can affect the result you get from an individual IQ test, especially in the short term. Adequate rest, nutrition, and state of mind improve your scores on the day of the test. General education or specific problem-solving exercises help in the longer term. Then there's a wide range of nootropic drugs. Take your pick. <span style="padding : 0px 1px 1px 1px; border : 1px solid #809EF5; cursor: wait; background: #FFFFFF ; color: #99B3FF">GeeJo (t)⁄(c) &bull; 15:46, 6 June 2006 (UTC)
 * See also: the answers given to the same question on the Miscellaneous Desk <span style="padding : 0px 1px 1px 1px; border : 1px solid #809EF5; cursor: wait; background: #FFFFFF ; color: #99B3FF">GeeJo (t)⁄(c) &bull; 16:00, 6 June 2006 (UTC)
 * Ginko Phytozome is suppose to increase circulation in the brain.


 * It is widely agreed (though i'm aware to a much less extent in the US) that IQ tests only measure your ability to do IQ tests. Whilst there are rough correlations, these can be argued to be nothing more than coincedence as there is no basis for the assumption that being good at an IQ test makes you more intellegent. However you can reach your maximum potential by getting adequate sleep and nourishment. I lost all faith in IQ test when me and a freind going through school, both of us doing pretty well, both expected to get high grades, and when we took IQ tests I got quoted at 125, 135, and 140 (quite a range you'll see), and this freind of mine came out in the low 80s. Also so many of the ones on the internet are a pile of bollocks, so you can ignore just about all of these . <font color="Green">Philc TECI 17:02, 6 June 2006 (UTC)


 * Problem solving skill practice. Many of these IQ tests are litte more than problem solving exercises, get a book full of them and practice doing them faster and faster. As someone just said these tests are essentially a measure of performance on themselves, the best way to get better is to take them over and over again in a stress free environment. You can even throw in a bit of psychology and reward yourself for improved performance. If you're more interested in actual intelligence I would suggest seeking an occupation that requires constant use of the brain (instead of physical or repetitive mental tasks) and taking up hobbies that require more active use of the brain and imagination - such as reading instead of audio or video and complex in-person game playing against elite opponents instead of more hand/eye coordination based repetitive video games against computer opponents.--Big O June 6, 2006


 * Yeh, the brain works like a muscle, the more you use it, the better it gets, but give it breaks, because it will get knackered. <font color="Green">Philc TECI 19:18, 6 June 2006 (UTC)


 * How to increase your IQ? My favorite way is by contributing to Wikipedia! --Ginkgo100 21:10, 6 June 2006 (UTC)


 * The answer is this. The only way to increase your IQ, as said, is to practice taking IQ tests, and the ones off of the internet won't do! You must have a psychologist do you. IQ doesn't matter anyway. — [[Image:Flag_of_the_United_States.svg|17px]] <tt> The </tt>  <font color=#006600>Mac Davis ] ⌇☢ &#xE0D;&#x19B;. 23:26, 6 June 2006 (UTC)

Plant watering Faux Pas
I've been watering my neighbour's indoor plants along with my own, and while both of mine are great, and two of their plants are as well, one of them has been doing poorly and I don't know why.

Before I started watering for my neighbour she let them get really really dry a couple of times, and I think we overlapped each other once or twice and they got a bit over-watered. Now I water all of them once a week, quite generously, and all but one are doing great. The one that's doing badly lost a bunch of healthy leaves about a month ago (I think cuz of the over-watering), but more disturbingly, while it grew a few new baby leaves a couple of weeks ago, they've gone brown from the stem out and fallen off. Now the few remaining big leaves are doing the same, dying from the stem out (the leaves themselves aren't wilted or brown), and I'm afraid the plant's dying. I don't know if I'm doing something wrong with the watering, or if it's something else. Any ideas?--Anchoress 15:57, 6 June 2006 (UTC)
 * If you don't have a clue about the last time somebody watered a plant, then you need to get a soil moisture gauge, and only water when it measures 'dry'. --Zeizmic 16:01, 6 June 2006 (UTC)


 * What kind of plant is it? Different plants have different watering requirements, and one that has had a shock probably needs to be handled quite delicately until it is healthy again.  --LarryMac 16:07, 6 June 2006 (UTC)
 * Zeizmic, thanks for the suggestion. LarryMac, I wish I knew what kind of plant it is, but my neighbours didn't keep the little plastic descriptor, and I know *nothing* about plants. It's young, about 8 inches tall, and the mature leaves are a little smaller than a computer mouse, crinkly almost like chinese cabbage, quite heavy and sturdy, very dark green with light green accents, almost like those plants whose leaves have purple accents, although this one doesn't have that. It had about eight leaves on it when she got it, all but three fell off I think cuz of over-watering, then it grew three new tiny leaves which all died, and now one of its remaining big leaves just died.--Anchoress 16:52, 6 June 2006 (UTC)


 * If it were me, I would not water the plant at all for at least a day or two. I would also go to the library or a bookstore and find a nice houseplant picture book to look through  (except that I already have The House Plant Expert by D.G. Hessayon, which has served me quite well), until I found the plant in question, then read the care information.  I will look through my book and try to find a plant of that description when I get home this evening.  --LarryMac 18:17, 6 June 2006 (UTC)


 * I would highly recommend checking the plant and its container for anything that looks suspicious (possibly bugs or something) just to be sure. What kind of container is it in? Are there any holes or other drainage devices on the bottom? If not, you need to stop overwatering it at all costs. With no way for water to drain from the soil overwatering can be extremely harmful. If there are drainage devices, a good bet is to wait until the soil is dry and then water it until you see some moisture coming out the drainage holes (or whatever). Hope that helps.--Big O June 6, 2006


 * A guess: some sort of Begonia? --Seejyb 22:22, 7 June 2006 (UTC)

[Unindenting]] Thanks you guys for all the replies. LarryMac, I definitely won't be watering the plant soon since I only ever water any of the plants once a week, and I don't water theirs if they seem like they've been watered recently. I appreciate you looking in your book, truthfully since these aren't my plants and I'm just watering them so they don't die (I'm not doing it cuz they're away or something, I just started watering them with my own cuz they were close to death several times), I'm not motivated to do any actual research, whether it be going to a library or buying a book :-).

TheBigO, it's just in the container they bought it in; it has holes in the bottom and I don't see any parasites or anything (they're indoor plants, for anyone who's having trouble imagining how I can water their indoor plants along with my own without them being away, we have skylights in our top floor hall, and glass bricks in the top floor floor, so on the second floor (ours) we get dappled natural light in the hallways). FYI thanks for the watering tips, it confirms that what I've been doing up to now is right.

Seejyb, funnily enough they just bought me a begonia along with a note thanking them for watering their plants lol, but this plant really doesn't look like that, it never had flowers, and the leaves are shaped like spades (on cards). They really really look edible, like really dark green chinese cabbage leaves with light green marking the veins.--Anchoress 05:17, 8 June 2006 (UTC)

My own DNA?
How can I see my own personal DNA sequence? Is my DNA consistent throughout my body, or do I have various DNA codes that can differ within my body? Is there a way to see what it says about me, e.g. if i'm prone for depression or if i'm closer to hunter-gatherer DNA than agriculturalist DNA? ALso, is the DNA different between men and women, i.e. does it say anything about a person's sex?--Sonjaaa 17:49, 6 June 2006 (UTC)


 * You could see your own DNA with a powerful enough microscope, or, in a certain manner, through Genetic fingerprinting if you were a suspect in a crime (though you wouldn't actually be seeing the DNA itself). DNA is consistant throughout all cells except the gametes, which contain only half your genes. DNA can be used to differentiate men from women quite easily, by looking at the chromosomes &mdash; XX for women, XY for men. &mdash; Asbestos | <FONT COLOR="#808080">Talk </FONT> <FONT COLOR="#808080"> (RFC) </FONT> 17:58, 6 June 2006 (UTC)
 * Good luck seeing a DNA sequence through a microscope. --BluePlatypus 23:54, 6 June 2006 (UTC)


 * You could sequence your DNA, but it wouldn't mean anything to you. At the moment, we don't know enough
 * about DNA to be able to say "this bit means you'll be like this", although some genes have been found
 * to be linked to some things. And as you seem to know, DNA mostly controls tendencies, not definates. Since you have :descended from hunter-gatherers who became agriculturalists, I don't understand that question.


 * Generally speaking, your DNA is the same in every cell in your body except for your germ cells (your eggs or sperm). However, mutations happen as your cells divide, and benign mutations can remain. In addition, female cells may do a bit more 'swapping' of chromosomes and suchlike in early stages of embryo development, leading to 'patches' of cells with slightly different DNA to each other. This can manifest in patchy skin. On top of this, chimeras are maybe more common than is currently recognised. Sometimes two early embryos 'merge', resulting in a human with two different DNA 'sections'. This can occasionally lead to problems such as athletes be considered men by DNA testing, but manifestly being women. Hope this is interesting, if not educational. Skittle 18:43, 6 June 2006 (UTC)
 * You can read about the 'swapping of chromosomes' (inactivation of one X-chromosome) that Skittle refers to here.
 * The cells of the immune system (both B-lymphocytes and T-lymphocytes) have unique DNA sequences, created through a process called somatic recombination. It involves both splicing together of various segments of DNA, and random insertion of nucleotides. In this way, the DNA encoding the lymphocytes' receptors (immunoglobulin or T cell receptors) is created. Each B- or T-lymphocyte clone has a unique receptor, which is not encoded in the germ line. This is, as far as I know, the only exception to the rule that all cells in your body except the germ cells have the same DNA. --vibo56talk 19:36, 6 June 2006 (UTC)
 * Not forgetting, of course, that cancer cells will have slightly different DNA from the rest of your cells.  Rockpock e  t  19:44, 6 June 2006 (UTC)
 * True. Another exception, I suppose, would be retroviral DNA, as well as herpesvirus DNA in neurons. You might not want to count that as part of your personal DNA, though. --vibo56talk 19:52, 6 June 2006 (UTC)


 * That was the thing. Thanks :-) I'm sure I heard there was some swapping involved as well, that led to more than just the two types. I remember thinking it was weird because it suggested DNA taken from one place would be slightly different to that taken from another. Skittle 22:32, 6 June 2006 (UTC)


 * Any two humans' genomes differ in only a tiny fraction of a percent of all base pairs. So, to see practically all of your DNA, check out Project Gutenberg's copy of the human genome. —Keenan Pepper 18:54, 6 June 2006 (UTC)


 * By studying the sequence on specific regions of your DNA (genes) you would be able to make pretty good guesses about some of your physical characteristics, including your hair colour or your skin colour. Sex is quite easy to determine by DNA as males and females differ in specific chromosome type, specifically in the Y chromosome and number of X chromosomes. A gene called SRY is a key factor in determining if you become a male. If you can find that you have that gene using a process called PCR there is a very, very high chance that you are a male.
 * We are not yet able to accurately predict the more complex characteristics you mention, but some scientists believe that in time things like depression way be able to be predicted genetically. Some recent research is making headway towards that (in this case, schizophrenia and not depression is the disorder being studied, but the principle is the same)  Rockpock  e  t  19:41, 6 June 2006 (UTC)

OS 9 in school computer labs
What are the chances that a school's main operating system is Apple OS 9? I've only just discovered that OS 9 only supports Java up through version 1.1, and so the educational program I've been working on for the past few weeks can't possibly work on OS 9. I know a lot of public schools are mac based, at least here in Massachusetts, but is it a good bet that they'd be using OS X by now?

Any wild guesses appreciated, &mdash; Asbestos | <FONT COLOR="#808080">Talk </FONT> <FONT COLOR="#808080"> (RFC) </FONT> 17:51, 6 June 2006 (UTC)
 * That will depend a lot on the budget the school system applies to their computers. Most of the schools I attended replace computers rarely enough that I would not be in the least surprised to find OS9 present. &mdash; Lomn Talk 18:41, 6 June 2006 (UTC)


 * It depends on how fast a particular school district refreshes their hardware. I've heard stories of schools with ancient Macs, but honestly no one is developing software for OS 9 these days and any school with the money to replace their computers at a good rate should have OS X by now. There are some multimedia studios trapped in OS 9 paying $$$ to be supported, but no one is going to do the same for a school. You might consider contacting Apple with this question.--Big O June 6, 2006
 * I've seen OS9 in the wild in education as recently as last year, but it's usually in settings where old software that still does its job is being run. I would not develop for it any longer, since it really is unlikely that anyone buying new software still expects it to run on 9. 71.34.105.97 19:08, 6 June 2006 (UTC)


 * I work for a company that writes software targeted at college-level institutions. We only dropped support for MacOS 9 a year and a half ago.  I expect that high schools are even further behind on the upgrade cycle. --Serie 20:43, 6 June 2006 (UTC)

Ok. I was concerned mainly because, out of the two Boston public schools that I've seen the computer labs for, one was Windows and the other OS 9. Obviously this a tiny sample, but I've seen a fair bit of anecdotal evidence on the web suggesting that many schools are stuck in OS 9 because of old software that they've grown reliant on. That said, looking at how I'd need to change my program, making it Java 1.1 compatible would be a horrendous job, and so I'm not sure that I'd do it even if 10% of schools still used OS 9... Thanks for all the replies, &mdash; Asbestos | <FONT COLOR="#808080">Talk </FONT> <FONT COLOR="#808080"> (RFC) </FONT> 20:21, 6 June 2006 (UTC)

Wow guys, I had no idea companies and schools still use Mac OS Classic. I thought all the Mac-using places upgraded to Mac OS X or switched to Windows. — <tt> The </tt>  <font color=#006600>Mac Davis ] ⌇☢ &#xE0D;&#x19B;. 04:43, 7 June 2006 (UTC)

Ick. My school still uses OS 9.2 iMacs (don't get me started on how bad they are, my 10 year old spywared PC runs better) or Win98 boxes with 480 x 320 res monitors...--Frenchman113 on wheels! 01:28, 8 June 2006 (UTC)


 * Yummy :) &mdash; QuantumEleven 09:32, 13 June 2006 (UTC)

Writely invites?
Does anyone have any? Where can I get one? Thank you! 71.34.105.97 19:08, 6 June 2006 (UTC)


 * Anyone know what this person is talking about? —Keenan Pepper 04:53, 7 June 2006 (UTC)
 * I would guess the anon is talking about Writely.-gadfium 06:12, 7 June 2006 (UTC)
 * Writely is an online word processor, currently invite-only (like Gmail at the start) and now owned by Google. You could Google for them, and find people offering them. That's what I did, and I now have about 35 extra Writely Invites, which I'm offering to all of you guys out there on the Reference Desk. Go to User:ByeByeBaby\Writely_Invites and leave your e-mail address (antispamed); I'll send them off when I can, probably tonight. Consider it your June paycheck. --ByeByeBaby 17:45, 7 June 2006 (UTC)
 * ajaxWrite is another great web-based word processor, if you guys hadn't already heard of it. You don't need an invite (you only need Firefox 1.5+). It loads fast and runs well too. -- Daverocks (talk) 07:20, 10 June 2006 (UTC)

Hydrogen bonding
This is on the topic of hydrogen bonding (got AS chemistry exam tomorrow so any answers quickly would be most appreciated). I was wondering why it is at 4 degrees celcius where the density of ice changes. I know that hydrogen bonding creates spacing in the stucture of the water but i dont understand why 4 celcius has any relevance?

thank you

chemaddict 19:30, 6 June 2006 (UTC)
 * The density of a substance changes over a range rather than at a specific temperature. The question you should be asking is why water is most dense at 4 degrees centigrade, for which, unfortunately, I don't have an answer. - Mgm|(talk) 19:50, 6 June 2006 (UTC)


 * Okay, ice is less dense than room-temperature water because the oxygens line up in a face-centered cubic lattice with hydrogens between them and relatively large interstices. The density of liquid water increases as the temperature decreases toward 4 celcius according to the normal trend most substances follow, but as it passes 4 celcius the crystal structure effect kicks in and the density increases with decreasing temperature. It's still a liquid, of course, but the molecules are moving slow enough that, on average, the low-energy positions in which the molecules are arranged like part of an ice lattice are favored, and temporary, rapidly rearranging interstices are formed. The 4 celcius density maximum just happens to be the point where the normal trend and the special backwards trend cancel each other out. —Keenan Pepper 20:11, 6 June 2006 (UTC)

On a more bizarre note, if water didn't do this at 4 C, then you might not be around to ask the question (human life and all that). --Zeizmic 20:25, 6 June 2006 (UTC)


 * I did not know there was such a thing as ice with a temperature of 4° Celsius. --Ginkgo100 21:05, 6 June 2006 (UTC)


 * Simple macroscopic answer is that, ice is less dense than water, and the density of water decreases as temperature increases. So at some point in between 0 and 100, liquid water must have a maximum density. However, if you want a more detailed explanation, noone can give you that, because there's still a lot of unknown stuff about the hydrogen-bonding networks of water, and a lot of recent developments in it too E.g. here. --BluePlatypus 23:52, 6 June 2006 (UTC)

Thanks
I just wanted to say thanks to all of the contributers here. The people here are really knowledgable and have help satiate my intellectual curosity on different occasions. Mayor Westfall 20:19, 6 June 2006 (UTC)


 * Although most of us are too poor, and get pizza slipped under the door, I have heard that there something called money, and that the Wikipedia project could use some. --Zeizmic 20:29, 6 June 2006 (UTC)


 * Wikipedia will send us pizza if someone donates money to them? I'd better raise the gap under my door. &mdash; Asbestos | <FONT COLOR="#808080">Talk </FONT> <FONT COLOR="#808080"> (RFC) </FONT> 20:44, 6 June 2006 (UTC)


 * I prefer to have my pizza faxed to me. :-) StuRat 03:20, 7 June 2006 (UTC)


 * Thanks. — [[Image:Flag_of_the_United_States.svg|17px]] <tt> The </tt>  <font color=#006600>Mac Davis ] ⌇☢ &#xE0D;&#x19B;. 23:54, 6 June 2006 (UTC)
 * And you're welcome. --Ginkgo100 03:44, 7 June 2006 (UTC)

I have ordered 40 Pizzas to the Wikipedia Headquarters. 12.183.203.184 17:19, 7 June 2006 (UTC)

wings
are there limits on the size wings can be on animals? ie whats the largest a wing could theorecilaty be at which point the extra muscles needed to move the wing outweigh the extra power from the wing? and also is there a smallest size at which point wings couldnt provide enough lift for the muscles and organs needed to surive?--Colsmeghead 22:01, 6 June 2006 (UTC)
 * I don't know the exact figures - but I do know that the Great Bustard is the heaviest flight-capable bird. I guess that the answer to your question would be 'not much bigger than that'. --Kurt Shaped Box 22:42, 6 June 2006 (UTC)
 * If you are willing to consider extinct animals, then see our article on quetzalcoatlus, which had a wingspan of up to 12 metres (or possibly even 18 metres). The Great Bustard linked to above has a 2.4 metre wingspan, for comparison.


 * If you want to restrict yourself to birds, but are willing to consider extinct ones, see Haast's Eagle, with a wingspan of 2.6 - 3 metres. I suspect one reason they are extinct is that the early Maori objected to their grabbing children (or even adults) and flying away with them.-gadfium 01:51, 7 June 2006 (UTC)


 * And a couple more for the sake of diversity: the largest known flying insect would be Meganeura, with a 75 cm wingspan, although it probably couldn't have flown with the higher oxygen concentration in the atmosphere of its day, and the largest bat, Pteropus, with a 180 cm wingspan.


 * Pterosaurs rule!-gadfium 02:02, 7 June 2006 (UTC)

As for the lower size limit, for birds it's around the hummingbird range. The limit seems to be the high metabolic rate required to keep those wings flapping which requires constant ingestion of flower nectar. For insects, the limit might not be a hard one; I think it's more of it being unnecessary to have wings to fly below a certain size. Wind currents will determine where such a small insect will land more than their wings, so what's the point in having wings ? StuRat 03:17, 7 June 2006 (UTC)


 * If its a gliding bird like the albatross surely it wouldnt need much more muscle. <font color="Green">Philc TECI 18:03, 7 June 2006 (UTC)


 * I doubt that albatrosses could grow much bigger than they currently are and still be able to fly. The largest species (e.g. the wandering albatross) can only take off from water after a huge run-up and from land only with wind assistance from a clifftop. There is actually a formula used to work out the energy needed for a certain bird of a certain mass to get airborne - I remember a discussion of it on usenet (I can't seem to find the post using Google at the moment). Beyond a certain body mass, the bird needs more energy to achieve takeoff than its body can provide at once. AFAIK, the relationship between mass and energy required for flight is not linear - if anyone can be more specific, I'd be really interested in hearing about it again... --Kurt Shaped Box 22:47, 7 June 2006 (UTC)


 * Well whatever the limit, it has to allow for birds with a wingspan well over thirty foot, to accomodate such creatures as the Pterosaur. <font color="Green">Philc TECI 15:50, 11 June 2006 (UTC)


 * To follow up on gadfium's point, in prehistoric times the atmospheric conditions were sufficiently different that very large wingspans were possible. ISTR Quetzalcoatlus was the largest beast known to have got off the ground. Grutness...<small style="color:#008822;">wha?  09:18, 8 June 2006 (UTC)


 * I don't think Quetzalcoatlus had the benefit of much higher oxygen levels than the present day ones. When Meganeura was flying around 300 million years ago, oxygen levels were about 35%, but Quetz had maybe a few percent more than current levels, 65 million years ago. See this chart.-gadfium 09:44, 8 June 2006 (UTC)

Quantisation of Angular momentum
How is angular momentum (L) quantised? My 1st year physics textbook (Matter and Interactions, Chabay and Sherwood) mentions several different quantisation laws for angular momentum ($$|L_{\mbox{trans}}|=N\hbar$$, components of L $$=\frac{N}{2}\hbar$$, and $$L^2 = \frac{N}{2}(\frac{N}{2}+1)\hbar$$ each for integer N). Which of these apply when? Or must they all be satisfied? This chapter is perhaps the textbook's weakest. (And by the way, where are all these quantisation laws on wikipedia? I couldn't find these or any of the others we learn [spring potential energy, etc.]) --대조 | Talk 22:16, 6 June 2006 (UTC)
 * Those would be the selection rules. Sporkot 23:38, 6 June 2006 (UTC)


 * There's a description at Angular momentum. Note this is for a spherically symmetrical system. Anyway, then the former rule is for the L component in the Z direction, and the L^2 value is for the expectation value of the total angular momentum. Since if Lz is defined, Lx and Ly are not. --BluePlatypus 23:43, 6 June 2006 (UTC)


 * Yes, I now vaguely recognise these in the article, but not in the form I can understand (I see that I perhaps don't make it 100% clear that I am in first year and not just reading a first-year can understand; or maybe first-year physics is more advanced in other courses/textbooks?) --대조 | Talk 00:10, 7 June 2006 (UTC)

The half-integer formulas do not apply to orbital angular momentum, which should only have integer multiples of Plank's constant. Only intrinsic angular momentum should have half-integer multiples. -lethe talk [ +] 06:20, 7 June 2006 (UTC)

Recycle Bin For Linux
It has come to my attention that the fact that when a file is deleted under Linux it is gone for good, is likely to cause plenty of problems for some people. Why doesn't someone produce an installable package that puts 'deleted' files into a sort of 'purgatory', a limbo between normal existance and non-existance so people can 'delete' and forget about most files and these will eventually become non-existant whilst they have the option to go back to the purgatory and retreive files if they make a mistake or have a change of heart. Some of you will come back with all this 'Linux is not Windows' rubbish, insistant on being different just for the hell of it - well don't; it makes me sick! This is a perfectly good idea and could solve a lot of problems for many people. Some of you may say 'code it yourself'. If I have to, I will, but since I don't know how to code and I have many other priorities right now it'll probably be at least 10 years so where do I put this good idea where skilled people will see it and fix it? --Username132 (talk) 22:42, 6 June 2006 (UTC)
 * I would be shocked beyond belief if there's not several apps like this already in existence; it was one of my weekly homework assignments in a mid-level CS course. &mdash; Lomn Talk 23:18, 6 June 2006 (UTC)
 * Open up a command prompt and type this in. The $ signs represent the prompt (don't type those in), and ^D is Control-D.

$ cd $ mkdir recycle $ cat > ~/bin/del for $f in "$@" do  touch $f mv $f ~/recycle done ^D $ cat > ~/bin/gc find ~/recycle -atime 7 -print0 | xargs -0 rm echo $PWD/bin/gc | at +1 day ^D $ echo $PWD/bin/gc | at +1 day
 * 1) !/usr/bin/bash
 * 1) !/usr/bin/bash
 * This will create a script called del that will move files to the recycle bin, a script called gc which runs once a day and deletes files that have been in the garbage can over seven days, and starts gc a day from now. The only caveats are that you need to type del instead of rm, and that it won't run recursively.  Also, it doesn't remember where the file was so it can restore it.  But for basic "Oh crap, I didn't want to delete that!" purposes, it should serve. --Zemylat 23:23, 6 June 2006 (UTC)
 * Well, if this question's poster really wants to use rm, he/she can type alias rm='del' into the shell. --Bowlhover 04:22, 7 June 2006 (UTC)
 * When you delete in DOS, it is deleted. When you delete in the shell in Linux, it is deleted.  So, why bash linux about it?  When you delete in Windows, it goes into the trash.  When you delete in KDE/Gnome (common desktops for Linux) it goes into the trash.  So, why bash linux about it?  Try comparing text-prompt to text-prompt and GUI to GUI. --Kainaw (talk) 00:09, 7 June 2006 (UTC)


 * Probably because for most people, Linux is a black box with text. They don't think of window managers when they think of Linux. --Zemylat 00:13, 7 June 2006 (UTC)
 * Exactly. Also, Linux users use the shell much more than Windows users use the command prompt, so it's more likely to accidentally delete a file in Linux (and not be able to restore it easily) than in Windows.  --Bowlhover 04:16, 7 June 2006 (UTC)

I just found the KDE article, in which everything is illuminated! --Zeizmic 02:08, 7 June 2006 (UTC)

MIT's Athena system has a "delete" function, which translates to mark and rm in a day. But I'm too used to rm to use it, which has been bad for me in the past. moink 03:10, 8 June 2006 (UTC)

Vitamin A
what is the number of overdose symtoms for vitamin A victims
 * See Vitamin A. Type it in the search box next time. — [[Image:Flag_of_the_United_States.svg|17px]] <tt> The </tt>  <font color=#006600>Mac Davis ] ⌇☢ &#xE0D;&#x19B;. 00:05, 7 June 2006 (UTC)

Humans and Raw Meat?
Before fire was invented, humans ate raw meat. So why is it that raw meat is considered so hazardous to us today? Is the meat different, or are we? --Zemylat 23:24, 6 June 2006 (UTC)


 * People are more fussy nowadays. Not much wrong with eating *fresh*, raw meat (aside from parasites). --Kurt Shaped Box 23:31, 6 June 2006 (UTC)


 * Not entirely true, KSB. In addition to parasites, besides us being different, the meat is different. The feedlot/slaughterhouse model means that human grade meat is very highly contaminated with fecal matter, whether it's beef, chicken or whatever. Also, animals (whatever they are) develop bacterial flora in their guts to handle whatever their main food is; that's why domestic pets have to be weaned onto raw food diets, because they typically lack the bacteria and even enzymes to properly process and absorb nutrients from the raw food. Funnily enough, meat prepared for raw consumption by animals is actually more sanitary than meat prepared for humans.--Anchoress 23:34, 6 June 2006 (UTC)


 * That's why I referred to *fresh* raw meat. :) I doubt whether tucking in straight from the warm belly of the cow you'd just shot would do you much harm once you'd become used to it. --Kurt Shaped Box 23:41, 6 June 2006 (UTC)
 * That's not strictly true either; chickens, for instance, are infected during their lifetimes with record rates of salmonella due to their high-density living conditions.--Anchoress 07:06, 7 June 2006 (UTC)
 * Would this be the case with wild chickens? With my original comments, I was kinda implying that the meat would come from a natural, 'non-messed with by humans' source. Sorry if I didn't make that clear... --Kurt Shaped Box 22:37, 7 June 2006 (UTC)
 * Um... I don't think there are any wild chickens, lol (except a few living in a commune in the north of England), the ability to survive without human help has been completely bred out of them. But both my answers are related specifically to the process of factory farming; AFAIK, game meat is as healthy as it ever was.--Anchoress 05:07, 8 June 2006 (UTC)
 * (edit conflict) Generally, neither is any different, we just decided that getting sick and dying due to food poisoning and parasites wasn't any fun. The high quality of our food intake is one reason that our life expectancy is so long. Okay, there is one difference - as we've developed civilization, our meat supply is no longer as fresh as it used to be, so bacteria have a greater chance of infesting meat as it travels from slaughter to the table. We still eat raw meat, if we take proper care -- ever heard of Sushi or Tartare? Ceviche? Carpaccio? Gored Gored? Kibbeh? Kitfo? (okay, now I'm craving some Kitfo. Kitfo lebleb, but kitfo nonetheless.) --ByeByeBaby 23:43, 6 June 2006 (UTC)
 * Japanese raw fish dishes are more properly called sashimi. -lethe talk [ +] 03:47, 7 June 2006 (UTC)
 * Damnit! I find all those raw meat dishes and screw up the most obvious one. Of course you're correct. --ByeByeBaby 04:22, 7 June 2006 (UTC)


 * Both to various degrees: Raw meat is processed industrially and has many opportunities for contamination and partial spoilage compared to, say, a classic hunter-gatherer society. Since the domestication of fire, humans have been able to kill some of the parasites in meats before eating, and now we've become dependent on some degree of preparing our food. Peter Grey 05:14, 8 June 2006 (UTC)

Note that the human appendix is thought to serve a purpose in a diet including occasional raw meat. Specifically, it allows bacteria useful in the digestion of raw meat to be retained, rather than flushed from the system during long intervals between raw meat meals. Thus, those lacking an appendix may be less able to digest raw meat than the rest of us. StuRat 03:34, 7 June 2006 (UTC)


 * Really? Our article on vermiform appendix doesn't mention that. Perhaps it should? --Shantavira 07:43, 7 June 2006 (UTC)


 * Good idea, I added it. StuRat 18:23, 7 June 2006 (UTC)


 * Don't forget to verify it. --Ginkgo100 talk ʘ contribs 20:44, 7 June 2006 (UTC)


 * StuRat, is this another one of your theories or do you actually have a reference for this? - Cybergoth 05:13, 8 June 2006 (UTC)


 * It's not my theory, I read about it many years ago. Unfortunately, I don't recall the source.  If you feel like tracking down sources, please do so. StuRat 19:15, 8 June 2006 (UTC)
 * Hmmm... a quick Google search did not yield any easy answers/sources. - Cybergoth 14:17, 9 June 2006 (UTC)


 * Don't forget that people aren't so fussy everywhere. I eat raw meat on a regular basis (in Japan), sometimes more than a few times a week. Chicken, horse, octopus, squid, and of course, fish, are eaten raw as a part of a completely normal (albeit slightly traditional) Japanese diet. freshofftheufo  ΓΛĿЌ  06:48, 8 June 2006 (UTC)


 * The cecum in herbivores is a pouch where cellulose is broken down by bacteria so that the animal can absorb it. The human appendix is most likely what is left of the same structure in an ancestral creature. I have never heard it suggested that it has anything to do with the digestion of meat. On the contrary, the enzymes responsible for digestion of meat (raw or cooked - no difference) come from the pancreas, entering the gut way up in the duodenum. Where does this theory about raw meat come from? --Seejyb 21:23, 9 June 2006 (UTC)