February 8

Firefox question

My firefox wasn't working correctly the other day, and it forced me to create a secondary user profile to open it up. Now it's stuck in the new profile. How do I switch back to the old one? -Tim Rhymeless (Er...let's shimmy) 02:36, 8 February 2006 (UTC)[reply]

Run it with the command line option "-profilemanager". See [1]. —Keenan Pepper 04:38, 8 February 2006 (UTC)[reply]

That has happened to me before. I found out it was because even though i had gotten out of firefox it was still running in the background (ctrl-alt-delete>processes>firefox.exe) so when i opened firefox again it then asked for a new account because the old one was still running (in the background) without me knowing it. gelo 04:53, 8 February 2006 (UTC)[reply]

Yeh, it's really weird; Firefox seems to have a problem with exiting properly on my laptop sometimes, although that never happens on my desktop machine. One of those weird bugs that have been hanging around for ages. enochlau (talk) 05:20, 8 February 2006 (UTC)[reply]

Music CD formats

Will a music CD bought in Egypt play on machines in the USA? Is there a difference in recording formats throughout the world and does that make a native CD incompatability from the continent to continent. Will a CD purchased in Egypt work on standard North American equipment?

Please do not post the same question on multiple different reference desk sections. It will waste the time of people trying to answer a question already answered elsewhere and we don't have different sections for fun. - 131.211.94.86 10:57, 8 February 2006 (UTC)[reply]
- ~~And your question has been answered on the Misc. Ref. desk.~~ Okay, apparently someone deleted your question and my answer over there. So here's the answer again.... Yes, the CD should play on any CD player as CDs don't have specific regions like DVDs do. Dismas|^(talk) 10:58, 8 February 2006 (UTC)[reply]
That was me, they posted it on all sections. - Mgm|^(talk) 16:03, 8 February 2006 (UTC)[reply]

Ankylosing spondylitis

sir can i know wat r the yoga treatments for ankylosing spondylitis

Have you read the article, ankylosing spondylitis? —Keenan Pepper 16:04, 8 February 2006 (UTC)[reply]

About that day questions of Modern Physics

On :7.6 Modern Physics

Once again I would ask :How does that formula derive?

I(\nu )={\frac {2(Ch)^{2}\nu ^{3}}{V}}{\frac {1}{exp({\frac {h\nu }{kT}})-1}}

Or

I(\nu )={\frac {C}{4}}\left({\frac {8{\nu ^{2}}\times hC}{V}}\right){\frac {h\nu }{exp({\frac {h\nu }{kT}})-1}}

--HydrogenSu 12:45, 8 February 2006 (UTC)[reply]

Hm...I'm working from the bottom up, so I'm starting to see where this is coming from. This expression was derived by Planck, and involves quantization of energy levels and black body radiation. --HappyCamper 16:32, 8 February 2006 (UTC)[reply]

The derivation is right there at Planck's radiation law, but it's not a simple one. It's worth noting Planck himself did not derive it, but basically did some curve-fitting and made a lucky guess. --BluePlatypus 17:43, 8 February 2006 (UTC)[reply]

Thank you two. I'll study this web you offered.--HydrogenSu 19:18, 8 February 2006 (UTC)[reply]

Blood

I know that human blood is red due to the presence of haemoglobin. But why different animals have different blood colour?

See Haemoglobin#Other biological oxygen-binding proteins. —Keenan Pepper 16:06, 8 February 2006 (UTC)[reply]

Yup, blue-blood.. it's not just for aristocrats anymore! Ask the Horseshoe crab! :) --BluePlatypus 17:46, 8 February 2006 (UTC)[reply]

I bet that is Hemocyanin, tho.

I think so too. I think instead of iron, copper might be involved. --HappyCamper 22:28, 10 February 2006 (UTC)[reply]

Math Expression (2)

          It seems to be a paradox.
          For
          : ${\mathcal {\mid }}\Psi (x,t){\mid }^{2}=A^{2}sin^{2}(kx)*cos^{2}({\omega }t)=0{\neq }1$ 
          which means that it does not equal to 1.
          Thus caused not coresponse Normalization.
          Known a standing wave is expressed  as
          : ${\mathcal {\,}}\Psi (x,t)=Asin(kx)*cos({\omega }t)\,$ .
          Can anyone talk about your thoughts? Thanks.

I don't know why cannot edit right now. I'd open a new to edit. In that question, ${\mathcal {\,}}sin^{2}X+cos^{2}Y{\neq }1\,$ The original Math formula is derived from ${\mathcal {\,}}sin^{2}X+cos^{2}X=1\,$ --HydrogenSu 13:15, 8 February 2006 (UTC)[reply]

I found I'm in messy. Better in writting with upload-file for discussing conviniently. I'm going to dinner. Will upload.--HydrogenSu 13:21, 8 February 2006 (UTC)[reply]

The first equation (the amplitude) is neither zero nor one, it's a function of x and t. The normalization condition in quantum physics is that the integral over the amplitude from -infinity to +infinity is unity (= 1). Let's simplify this by taking the time-independent case (this has no effect on the amplitude). Set t=0 and the wave equation is ${\mathcal {\,}}\Psi (x)=Asin(kx)$ , and the amplitude ${\mathcal {\mid }}\Psi (x){\mid }^{2}=A^{2}sin^{2}(kx)$ . The integral of this over all x is infinity. So this is not normalized, or normalizable. Also, it does not satisfy the boundry condition for quantum wavefunctions that the amplitude must approach zero as x approaches ±infinity. Which brings me to the two main points here 1) A standing wave is never a solution for the Schrödinger equation for infinite boundaries. It is, however, the solution to the S.E. for a particle in an infinitely deep, finitely sized, potential well (the particle-in-a-box problem). 2) A plane wave (as it's called) cannot be normalized. (Although they're still used a lot in quantum mech, but one must keep this in mind). --BluePlatypus 17:36, 8 February 2006 (UTC)[reply]

Correcting myself: The integral is undefinied, not infinite. (lim ?->infinity of cos(?) is not defined) The point still stands though. --BluePlatypus 05:51, 9 February 2006 (UTC)[reply]

I see. I should consider more about in Physics. But,some of your reply,which have just been also my questions for a long time. Why do some constants at bondaries have to be set 0? For ex: $y=c_{1}x^{\lambda _{1}}+c_{2}x^{\lambda _{1}}$ in Q.M. about your reply above. In fact,I seem to have some more questions after reading the reply. Wait for me please. It's dark-night in Asia. I'm a little out of brain. Tomorrow. Got sleeping...--HydrogenSu 19:57, 8 February 2006 (UTC)[reply]

That doesn't really have much to do with quantum mechanics in itself. Boundry conditions are important in all differential equations. I'd suggest you study up on partial differential equations, it's really necessary to understand QM properly. The Schrödinger equation is, after all, just a PDE, and the methods used to solve it are the same as for other PDEs. Indeed, in general it's advisable to study as much math as possible if you want to get into quantum mech. Otherwise there's a big risk you'll miss the 'big picture' and start assuming general mathematical principles are QM-specific. --BluePlatypus 06:00, 9 February 2006 (UTC)[reply]

I'm learning Physics,not math.--HydrogenSu 09:04, 10 February 2006 (UTC)[reply]

You can't learn physics without math. Lots of math. Or go look at the math requirements in any university programme in physics.--BluePlatypus 18:34, 10 February 2006 (UTC)[reply]

<Some of the user's comments were too offensive and involved person attacks. It was off Topic. Thus it is deleted here.>--HydrogenSu 19:07, 15 February 2006 (UTC)[reply]

C'est Maths...Je n'en vous ai pas dit , auquels dont j'irai etudiè plus. C'est tout et la fin. --HydrogenSu 19:07, 15 February 2006 (UTC)[reply]

computer programme

heloo , i want to know the source code of a programme. kindly help me in this .the problem ststement is" write a programme in c to find the sum of possitve odd numbers and product of even numbers less than 50"

For each one, you'll need to create a counting variable, say "sumOdd" and "productEven" (sumOdd should be set initially to 0, and productEven to 1 - remember the additive and multiplicative identity!).

For the first question, start with 1, and use loops to increase it by 2 until it hits 50, making sure to add each one to sumOdd.
For the second, start with 2, and use loops to increase it by 2 until it hits 50, making sure to multiply each one to productEven.

As for the code, you'll have to take care of that yourself. Hope this helps :o) tiZom_{(the man)} 14:38, 8 February 2006 (UTC)[reply]

I won't write the program but I'll tell the results so that you can check. The product of even numbers from 2 to 48 inclusive is 1.04093968527333e31; the sum of odd numberd from 1 to 49 inclusive is 625. – b_jonas 20:24, 9 February 2006 (UTC)[reply]

WINFILE virus

Do anybody know how to remove the virus named WINFILE?It is a folder-like virus and spread inside the computer by creating the new unknown folder itself.

I think you've been hoaxed. It sounds like a legitimate windows subfolder. If you received this in an email from an unknown sources or forwarded through a friend and not a official work/ISP/school source, it's best to ignore it. If you suspect viruses in your system, just get a piece of antivirus software (with updated virus definitions) and scan your entire system. - Mgm|^(talk) 16:08, 8 February 2006 (UTC)[reply]

I think McAfee and Norton have a web page that will scan for viruses for free.

Try this too. Quick and easy, and useful. --HappyCamper 22:19, 10 February 2006 (UTC)[reply]

Batch PDF -> TXT conversion

Is there a tool for batch PDF -> TXT conversion? The source PDFs are scanned documents with the embedded text layer. OCR is not needed at all because you only need to extract the embedded text from them. There are about 46,000 of them so I really need a tool that asks no questions. I tried pdftohtml.exe. It simply fails to see the text layer. -- Toytoy 14:57, 8 February 2006 (UTC)[reply]

You could try the pdftotext tool which comes with Xpdf. --cesarb 15:17, 8 February 2006 (UTC)[reply]

For the record, PDF to text conversion typically does involve a step akin to OCR. (In fact, a converter I once examined the source code of had a large module named "ocr".) The reason is that PDF is not designed to encode text; it (like PostScript, which has similar difficulties) is designed to encode marks on a page. You often find that text converted from PDF (just like OCR'ed text) has lotso fw ord-boundar yerrors, because the PDF software basically sees a bunch of letters drawn on the page, and doesn't necessarily know how they're supposed to go together as words. -- Steve Summit (talk) 06:57, 9 February 2006 (UTC)[reply]

More precisely, that's caused by fancy DTP software that insists on doing its own kerning and stuff. That means it has to position each letter individually rather than letting the PDF/PS viewer do it. Of course, just about every program that produces PDF (including TeX) does that, so you probably just have to deal with it. —Ilmari Karonen (talk) 07:23, 9 February 2006 (UTC)[reply]

In other words (I can't stress this enough), DON'T USE PDF! (there you go, you've got me shouting now :( ) Of course, if you have to handle text that others have saved as pdf, you're screwed. But let this be a lesson to never inflict this misery on others and never use pdf yourself. DirkvdM 12:14, 9 February 2006 (UTC)[reply]

Well, PDF does have one tiny virtue: IF you're concerned about transmitting more than just mere information, if you're consumed with worry over precisely how that information is presented, if you want to control the size and position and color and font and every other detail of every mark on the page, if you're unclear on the concept of fungible electronic documents and would really be more comfortable passing sheaves of the the ashes of dead trees around, PDF is at least a better option in some respects (i.e. in portability if not in terms of machine-readable information recovery and editability) than Microsoft Word .doc format. --Steve Summit (talk) 13:23, 9 February 2006 (UTC)[reply]

PDF, like PostScript, is a perfectly good format for storing and transmitting pages to be printed. It's what I use whenever I want to send off my work to a print shop. The problems only start if you want to do anything with it except view or print it. —Ilmari Karonen (talk) 13:48, 9 February 2006 (UTC)[reply]

Not to get in a big flamewar over this (though I could, mind you, I could :-) ), but I think a safer statement would be "The problems only start if you want to do anything with it except print it". (That is, it ain't always perfect for viewing, either.) -- Steve Summit (talk) 00:13, 10 February 2006 (UTC)[reply]

Right, pdf is good for printing. But one should store it as something else and then only temporarily make a pdf version for printing. And Steve, the doc format is so unsafe that even microsoft has decided to abandon it (or so I've heard). DirkvdM 19:39, 9 February 2006 (UTC)[reply]

I'm sorry, did I give the impression that I was defending .doc format or recommending it in any way? :-) Not to worry... --Steve Summit (talk) 00:25, 10 February 2006 (UTC)[reply]

The files were scanned documents that were poorly OCR'ed by some lowly-paid poor office workers. I have 46,000 such garbage text files now (1.6 GB). The Xpdf works. I find myself badly screwed anyway.

i t s p r i n c i p a l o f f i c e i n t h e U n i t e d S t a t e s ,

a l l books, l e d g e r s , a c c o u n t s ,

c o r r e s p o n d e n c e , memoranda, f i n a n c i a l r e p o r t s

, and o t h e r r e c o r d s and documents i n i t s p o s s e s s i o

n o r c o n t r o l f o r t h e p u r p o s e s o f v e r i f y i n g

any matter c o n t a i n e d i n t h e r e p o r t s r e q u i r e d

under p a r a g r a p h I11 o f t h i s Order.

I plan to write a big PERL script to salvage the data someday. It'll involve a huge dictionary, a replacement engine using some sort of maximum length matching algorithm and some black magic or the dark side of the Force. Or I'l redo the OCR. Life sucks and PDF is evil. -- Toytoy 05:17, 10 February 2006 (UTC)[reply]

"because the PDF software basically sees a bunch of letters drawn on the page, and doesn't necessarily know how they're supposed to go together as words"

then how come acrobat lets me copy and paste text to the clipboard with no trouble at least in most of the pdfs i come accross. Plugwash 10:36, 11 February 2006 (UTC)[reply]

That's a really good question. I don't know. (Perhaps this helps explain why sometimes you can't copy the text.) Steve Summit (talk) 15:14, 11 February 2006 (UTC)[reply]

A possibility: Put the PDF files somewhere on the internet where Google can find them and access them using google search. Google creates HTML versions of PDF.WAS 4.250 04:46, 12 February 2006 (UTC)[reply]

Omnipage can probably handle them. It doesn't come for free but it will save you a lot of time and effort. --WS 00:50, 13 February 2006 (UTC)[reply]

B and G mode in wireless networks

I would like to know what the difference between B mode and G mode is in wireless networks. I have tried finding the answer on my own but I could not find it anywhere. Thanks! 62.194.16.204 15:02, 8 February 2006 (UTC)[reply]

The answer is at the IEEE 802.11 article (the B mode is in fact 802.11b and the G mode is in fact 802.11g). --cesarb 15:19, 8 February 2006 (UTC)[reply]

In a nutshell, the b and g versions work on the same frequency, but under ideal conditions, g can jam in more stuff, due to fancy signal processing. In the article, it mentions that g may be a load of hype, because it suffers heavily from interference. --Zeizmic 15:21, 8 February 2006 (UTC)[reply]

Other notable differences are that b has a max transfer rate of 11 Mbit/s as opposed to g's 54 Mbit/s. b only supports up to WEP while g supports WPA. -- Daverocks (talk) 10:54, 9 February 2006 (UTC)[reply]

education

please give me a description on what this phrase means:

"We dont need no education"

and please help me explain why we need an education

Please don't post the same question at multiple reference desks. This has already been answered at the language desk. —Keenan Pepper 16:08, 8 February 2006 (UTC)[reply]

Old glass

Is Glass a solid or does it move at a very slow pace?

You'll find the answer in our article about Glass. LarryMac 15:53, 8 February 2006 (UTC)[reply]

Aquatic life

Please could you tell me how aquatic animals and plants get there oxygen from water? Thankyou! From Hannah

Animals get their oxygen with their gills. Plants probably have different ways, and they don't use up oxygen anyway, they produce it via photosynthesis. —Keenan Pepper 16:00, 8 February 2006 (UTC)[reply]

Well, where do they get their CO2 from then? Anyway, plants do use oxygen during certain cycles of their metabolism, it's just that over time the net result is a consumption of CO2 and production O2. But to partly answer the question, a liquid with a gas over it will absorb some of that gas (I'm probably not using the right terminology here). So since there are CO2 and O2 in our atmospere, there will be some dissolved in the water. How the planmts and anmimals take that out of it is a different matter. Aks at the biology ref desk (before you start looking for that - there isn't one :) ). DirkvdM 12:18, 9 February 2006 (UTC)[reply]

La Mieux Nouvelle Poste En Mes Physique Modernes Questions

[2] On which,I did some deriviation about Plank's ${\mathcal {\,}}{\frac {h\nu }{e^{h{\nu }/kT}-1}}\,$ combining with S.R. in bravely. I'm not sure taking

{\mathcal {\,}}Im{\cdot }exp({\frac {2mc^{2}}{mv^{2}}})\,

Is it(taking Im{exponential}) right? or wrong?

Sorry for my messy writting on which. --HydrogenSu 16:09, 8 February 2006 (UTC)[reply]

I took a look at your equations...I'm not really sure what you are trying to derive though. Could you elaborate a bit more? --HappyCamper 16:25, 8 February 2006 (UTC)[reply]

None...I'm busy and cannot rewrite it. So forgive my messy writting. Thanks for your care.

And I just tried to do it for fun only. It doesn't matter on my tests and examinations in 1 year for going a physics institute.--HydrogenSu 19:13, 8 February 2006 (UTC)[reply]

Photons don't have a resting mass, so you can't set h? = mc². --BluePlatypus 17:07, 8 February 2006 (UTC)[reply]
Alright. Thanks. Can we set ${\mathcal {\,}}h\nu =pc\,$ --HydrogenSu 18:48, 8 February 2006 (UTC)[reply]

Yes, but what exactly are you trying to derive? --BluePlatypus 06:17, 9 February 2006 (UTC)[reply]

J’en serai pour“fun”. C'est tout.--HydrogenSu 12:47, 10 February 2006 (UTC)[reply]

Haha, it just struck me what a bad section name this is. When you make a new post, are you going to change it? =P —Keenan Pepper 23:48, 9 February 2006 (UTC)[reply]

À vous:

Qel puis-je dire? Je ponse que chaque on, peut poster ici liebétment. Je sais Wiki est liebeé. Ne critisez pas cela dans ce monde. --HydrogenSu 09:29, 10 February 2006 (UTC)[reply]

S'il fait du soleil à Wikipédia, il en fait partout :-) I have a better idea for you...are you familiar with statistical physics? See if you can derive the pressure of a photon gas. That is quite an interesting exercise too. --HappyCamper 22:15, 10 February 2006 (UTC)[reply]

Chlorine atoms in gastric acid

I asked this question many months ago at Talk:Gastric acid and never got an answer, so I'm asking again here: Where does the body get chlorine atoms to make HCl from? From salt (NaCl)? If so, does this mean that while eating too much salt may be bad for your blood pressure, eating too little may make it impossible for you to digest your food? Angr/talk 16:43, 8 February 2006 (UTC)[reply]

Well, you need salt (and other electrolytes) to live. The body relies on pretty constant levels of electrolytes for a number of things (e.g. osmotic pressure, electrochemical gradients), so without chlorine and its counterions you'll be doing pretty badly. My guess is that you'll run into other problems long before you notice digestive ones. The condition of too low chlorine concentration is called hypochloremia. Oh, and it gets the ions from whatever you eat, salt and everything that contains it. You'll probably notice a pretty strong craving for salt before your electrolyte levels get too low. --BluePlatypus 16:59, 8 February 2006 (UTC)[reply]

[edit conflict] Chloride depletion is known as hypochloremia. As the article says, it's rare, because you don't excrete that much chloride, and it's in so many foods. Anyone who had hypochloremia would probably also have hyponatremia, or sodium deficiency. —Keenan Pepper 17:08, 8 February 2006 (UTC)[reply]

Actually, it's potassium deficiency that results from chloride deficiency. alteripse 22:00, 8 February 2006 (UTC)[reply]

Really? Could you explain why that is, or add it to the hypochloremia or hypokalemia articles? —Keenan Pepper 22:53, 8 February 2006 (UTC)[reply]

A complex question/problem - I'll try to explain but Alteripse can correct me if I am wrong. Chloride depletion often happens in the setting of vomiting (you vomit and therefore deplete hydrogen chloride/hydrochloric acid). This leads to 1) metabolic acidosis and 2) dehydration. The body tries to retain sodium and water to prevent catastrophic dehydration and shock. The main defence is at the kidneys - they reabsorb sodium and water, but at the expense of excreting potassium. This results in hypokalemia. - Cybergoth 02:54, 9 February 2006 (UTC)[reply]

Close, but Cl deficiency results in metabolic alkalosis, not acidosis, and is usually accompanied by mineralocoarticoid excess and often volume extracellular fluid depletion. All those factors combine to move K into cells, and into urine, resulting in lower amounts of K (hypokalemia) in blood and ECF. Classic example are pyloric stenosis, cerebrospinal fluiddrainage]], prolonged nasogastric tube drainage, cystic fibrosis in a hot summer. alteripse 11:38, 9 February 2006 (UTC)[reply]

Doh! That was a typo - I meant metabolic alkalosis. Alkalosis would cause potassium to move into cells, but there would be no net loss of potassium from the body. However, the effect of increased mineralocorticoid would be increased potassium loss in the urine. The other factor in dehydration is increased anti-diuretic hormone (ADH) secretion which can sometimes lead to hyponatremia. Dang, this reminds me too much of Nephrology Rounds at St. Mike's! - Cybergoth 23:05, 9 February 2006 (UTC)[reply]

What else do we eat besides salt that contains chlorine? Especially, what do we eat that provides enough chlorine to keep us in gastric acid? Fatty acids and carbohydrates are made up almost exclusively of carbon, hydrogen and oxygen, and protein those three plus nitrogen, right? I thought we only got trace amounts of other necessary elements (sodium, potassium, zinc, what have you); and considering how scarce salt was to people who lived far away from the ocean until relatively recently in human evolution, it seems surprising that we could consume enough chlorine to produce enough gastric acid to digest food. And yet, obviously, we must get the chlorine from somewhere. Angr/talk 17:11, 8 February 2006 (UTC)[reply]

Any substance that contains chloride ions is by definition a salt (ionic compound). But keep in mind that sprinkling white crystals on food is not the only way to consume salt. Many foods are naturally salty, for example meat, because the animal the meat came from needs mostly the same electrolytes as humans. Some vegetables are also naturally salty (celery and tomatoes?) because the plant takes salt from the soil and concentrates it. —Keenan Pepper 17:57, 8 February 2006 (UTC)[reply]

Here's a random table of the sodium content of various foods: http://oto.wustl.edu/men/sodium.htm (Sodium will usually correlate positively with chloride, but there are exceptions.) Processed foods with added salt have the most, of course, then meat and dairy products, but things like celery and spinach also have a significant amount. —Keenan Pepper 18:03, 8 February 2006 (UTC)[reply]

Also note that the sodium and chlorine requirements for people are quite low, since both can be recycled almost indefinitely in the body. It would be a huge task, in modern society, to eat so little salt that you actually suffered from a deficiency of either element (unless, of course, there is something wrong with your body's ability to retain sodium and/or chlorine). One restaurant meal would probably provide you with enough salt for a year, as would almost any processed foods (Campbell's Cream of Sodium soups come to mind, :-)). StuRat 18:28, 8 February 2006 (UTC)[reply]

Secret URL

If I put some files at some URL (using Apache), which I don't tell anyone, and don't link to from anywhere else, are the files still discoverable in some way that I'm not thinking of?

I'm not talking about classified data here, just embarassingly personal stuff.

I'll have to clear histories and caches of any public browsers I use to access the files.

I'll use some obscure URL to try to avoid dictionary attacks.

Thanks. 128.220.220.95 19:25, 8 February 2006 (UTC)[reply]

Make sure the folder contains an index.htm file, so people can't do a directory listing. Notinasnaid 20:13, 8 February 2006 (UTC)[reply]

Another way it could be discovered is if you have links from your secret pages to some outside page. For example, if your personal page is http://www.mydomain.com/embarassingstuff.html, and on that page you have a link to http://www.someoneelsessite.com/, and click to follow that link, the http logs at someoneelsessite.com will normally record that a link was followed to their site from http://www.mydomain.com/embarrassingstuff.html. Anyone who has access to the http logs of that site would know about your page via the referer. Some browsers have the option not to transmit the URL of the referring page with a request for a page, so either be sure to browse from that page using such a browser with the appropriate option set, or else just don't put any external links on your page. Chuck 20:40, 8 February 2006 (UTC)[reply]

If you're really worried you might as well use robots.txt so that it at least isn't indexed by a search engine if someone does somehow link to the URL. — Laura Scudder ☎ 23:20, 8 February 2006 (UTC)[reply]

That's a voluntary procedure by the spiders, I'd assume. If you have data stored on the internet in a public (even unknown) area, it will be found eventually by something like Google (spiders aren't limited to simple "dictionary attacks" or linking, they're more likely to find it through the IP of the host or something like that). All major search spiders seem to play by the rules and when they find something like robots.txt they ignore the rest of the directory, but there's no reason to assume that someone with deliberate intent would ignore it as well. The only thing you can really do is encrypt, or password protect either the files themselves or the directory using Apache. freshgavin TALK 03:02, 9 February 2006 (UTC)[reply]

Even assuming you follow the above (good) advice, another good idea would be to encrypt any information you store online that you don't want other people reading/seeing - on its own, security through obscurity is almost never a good idea. NeoCrypt is an open-source encryption program (Microsoft Windows version available) that will probably foil any amateur attempts at reading your data, but this is by no means the only choice. And then, there's also the obvious-but-still-worth-mentioning solution: don't post anything embarassing on the internet, period. --P e ruvianLlama^(spit) 05:16, 9 February 2006 (UTC)[reply]

Notinasnaid made a good point about including an index.html file. But even if you've got one, there are other ways your web server might "helpfully" reveal your secret file. For example, if you go to the (deliberately misspelled) URL http://www.eskimo.com/~scs/secrte.html, you'll get to the file "secret.html", because eskimo.com's copy of Apache corrects the misspelling for you, and reveals the secret file even though you didn't guess its name exactly.

Another good thing to do is to make the directory non-world-readable, so that the web server (assuming it's running as other than root) simply can't list its contents and give inadvertent help to someone who's fishing. I've been known to hide files inside a directory that's hidden inside a non-readable directory, so that browsers can't even find the name of the secret directory, let alone the files in it.

As PeruvianLlama correctly said, though, "security through obscurity" is usually a bad idea. The general rule is that if you don't want to make a file public, don't put it on a public web server, period. There's always some new or unsuspected piece of software that's jumping out when your back is turned and going way out of its way to help people find useful data, including the data you most definitely didn't want anyone to. Just about every month you read about a case somewhere in which some dreadfully private information -- things like files full of Social Security or credit card numbers -- was not only (a) accidentally left on a public web server, but also (b) indexed by google. I've got a number of web pages which I've never linked to or otherwise made public (because they're not done yet, not because they're secret) and google and several other search engines had them indexed within days of their creation. (I still haven't figured out how.)

(With that said, though, I use the "secret file" trick to transfer semisensitive data all the time -- did it just this week, as a matter of fact. Imperfect though it is, it's a vital technique, because sometimes HTTP is the only way to get a file from one machine to another, because HTTP is so darn ubiquitous, and port 80 is open through virtually every firewall.) Steve Summit (talk) 06:47, 9 February 2006 (UTC)[reply]

...except when it isn't. I once plugged my laptop into an Ethernet jack at a school and found that every port except 80 worked. Presumably they had some sort of filtering proxy that they wanted people to use, and had blocked port 80 to enforce it. Not knowing the address of the proxy, I ended up having to tunnel port 80 over SSH to get on the web. (Port 22 worked just fine.) —Ilmari Karonen (talk) 07:13, 9 February 2006 (UTC)[reply]

Ah, yes, port 22. I often wonder if people who are adamant about security, and who provide ssh and insist that it be used, realize what a double-edged sword it is, in that its port forwarding features let us trivially turn those oh-so-restrictive firewalls into so much swiss cheese... ---Steve Summit (talk) 00:20, 10 February 2006 (UTC)[reply]

Thank you all for your helpful answers. 128.220.220.95 16:34, 9 February 2006 (UTC)[reply]

Strange! Why CAN not edit again!

Debye's Capacity Theory I derived Debye's Capacity theory. Please see on (part 1) [24] and on (part 2)[25] .The final part , part 3, which will be uploaded tomorrow. It’s now dark-night in Asia. Not convinience.Sorry.

Anyway saying thanks first for any correction if my deriviation is wrong.--HydrogenSu 19:41, 7 February 2006 (UTC)

Are those questions reminiscient of homework questions? Well, to be honest, I've given this question to so many students tnat if you get the correct formula in the end, you did not make a mistake. Have a bit of confidence in yourself :-) It is virtually impossible to make a mistake in the derivation and still end up with the right expression. --HappyCamper 16:37, 8 February 2006 (UTC) Have you looked at Debye model article? hydnjo talk 17:51, 8 February 2006 (UTC)

This article above is retrieved from. ....><" Strange! Why not edit again! Angry.....><" Forget it. =7

I had "browsed on" it only but had not "looked at" it. One reason was that I prefered my professor's deriviation from Debye.. The 2 pictures uploaded was copied from it + my thinking. Made by the both. In fact I derived a shorter one for simplying. I guess this kind of "homework" should be checked myself and will be better. Not appropriate uploaded on webes. My true thoughts. :) --HydrogenSu 19:47, 8 February 2006 (UTC)[reply]

1 in 20?

I've been learning about statistical testing(especially the t-test), and something bothers me. If you use a p<.05 cutoff on a lot of tests (which as I understand it the scientific community does), doesn't that mean that 1 out of every 20 confirmations is a false positive? Even a p<.01 cutoff means 1 out of every 100 confimations with that cutoff is a false positive. In fact, if the tests are as widespread as I've heard they are, the proportion of false positives should be very close to 1/20 and 1/100 respectively, based on the law of large numbers. If I'm right, that means countless important studies got totally the wrong answer from the t-test, and trained statisticians have been relying on it despite that. So, how am I wrong? Black Carrot 20:17, 8 February 2006 (UTC)[reply]

You're not, at least on a basic level. However, "important" studies tend not to be done just once--they're done again and again. For example, if there were one, and only one study which indicated that smoking was linked with lung cancer, at a p<.05 cutoff, there might be a 5% chance it was wrong. (Even this is an oversimplification, because what p<.05 really means is that if there were no link between smoking and lung cancer, a study would be less than 5% likely to give the results seen in this study. Which is not quite the same as saying the conclusion that smoking and lung cancer are linked is less than 5% likely to be wrong.) But there hasn't been just one study linking smoking and lung cancer. If there were two studies linking smoking and lung cancer, each of them alone with a p<.05 cutoff, the two together would provide a much higher level of certainty, around .05*.05 = .0025. (Again an oversimplification.) In fact, dozens of studies have linked smoking and lung cancer, and all of them combined would give a p-value well below .000001.

This is why scientists tend to only "tentatively" accept hypotheses which are supported by only a single study, even if they can't find any problems with the study itself. But you're right that out of all the new scientific announcements which are reported credulously by the popular press ("Eating ten bananas a day reduces your risk of brain cancer!"), supported by only a single study each, some significant number of those will turn out to be wrong. Chuck 20:51, 8 February 2006 (UTC)[reply]

That makes sense. Thanks, I was a bit worried. Black Carrot 03:46, 9 February 2006 (UTC)[reply]

Here's another data point (or set of data points). A while back I read that there had been something like 60 different studies investigating the possible links between (a) living or attending school underneath high-voltage electric transmission lines and (b) getting leukemia or other forms of cancer. Now, something like three of those studies showed a faint but barely significant statistical correlation. The other 57 did not. The scientific community says, we believe there's no correlation between power lines and cancer. But the people who believe there is such a connection can always point at just those three tests... (Disclaimer: I don't remember where I read this and I made up the 3/60 numbers, but the real numbers in the article made the same point.) Steve Summit (talk) 06:19, 9 February 2006 (UTC)[reply]

A few years ago I discovered something while working in a university data centre that worried me, perhaps wrongly. As it was represented to me, statistical packages can apply a large number of tests to a data set. Habitually, researchers would collect a data set, then automatically apply every available statistical test. If any of them produced the target results, then those results would be published. Perhaps naively, this has led me to suspect any study which relies on statistics for its result, or at the very least to think that this technique introduces its own margins of error. Any comments? Notinasnaid 13:31, 9 February 2006 (UTC)[reply]

Presumably such a thing could be done, but it's usefulness would be limited. Only certain statistical tests are appropriate for answering certain questions, and the editors at scientific journals would probably catch on to anything too painfully obvious. More generally, serious researchers tend to look down on such techniques as mere data mining. This has been drilled into my head: my two econometrics teachers in grad school harped on the inelegance and dishonesty of "data mining" at seemingly every opportunity. --George 20:43, 9 February 2006 (UTC)[reply]

Assuming a large number (interpret that any way that's interesting) of studies based on such statistics give the wrong answer, which obviously and hopefully is wrong, what effect would that have on scientific knowledge? What things would suffer most, and what would suffer first? How wide would the damage spread, and would it get caught when the results were compared with other things?

Retinal Regeneration

I know nerves tend not to grow back. For instance, a severed spinal cord means you're paralysed for life. A stroke means the brain has to work around the damaged section. However, I've heard they are actually capable of growing back to some extent, in some circumstances. Is it at all possible for an eye with a damaged retina to partially or completely grow it back? Is it likely? Has it ever happened? If so, how? If not, why not? Black Carrot 20:21, 8 February 2006 (UTC)[reply]

Google is your friend here. Looks like a scam. --Zeizmic 22:43, 8 February 2006 (UTC)[reply]

Peripheral nerves do grow back at the rate of 1mm/month. When having teeth pulled in the lower jaw a not infrequent complication is an injury to the nerve that goes to the lip. Should that happen, feeling often returns after several weeks, and one should give up hope only after half a year.

However, the optical nerve and the retina are part of the brain, anatomically speaking, so injuries will not heal. 82.26.163.213 23:07, 8 February 2006 (UTC)[reply]

How able nerves are to regenerate, or how well a brain works after it's damaged also depends on the age of the patient. Cells in younger people tend to be able to restore themselves better than in older people. - Mgm|^(talk) 09:34, 9 February 2006 (UTC)[reply]

One class of nerve cells do grow back. Olfactory receptor neurons (the little pieces of your nervous system which stick out into the air, allowing you to smell things) do regenerate. There's a lot of research being done on trying to regenerate other nerves using olfactory cells. -- Finlay McWalter | Talk 20:07, 9 February 2006 (UTC)[reply]

I'm hearing a bit of disagreement here. One person seems to say brain nerves can regenerate(depending on age), another says it's just peripheral nerves, another says there's an exception to that, and I have no idea at all what Zeizmic is talking about. Black Carrot 01:38, 10 February 2006 (UTC)[reply]

Bodies of water.

Could you please tell me which 7 seas they are referring to when they say "Sailing The 7 Seas". Thank you.

See the article on Seven Seas. Chuck 22:07, 8 February 2006 (UTC)[reply]

Conservation of Energy

I have been thinking about this question asked by one of my lecturers for sometime, without getting anywhere.

Consider a spring that is bound into compression by a rigid string. If the whole thing is immersed into a weak acid that eats away slowly at the metal of the spring, (but is un-reactive to the string), what happens to the stored mechanical energy?

It's converted to heat. Imagine two springs submerged into two vats of acid: one spring is bound, as you describe, and one is unbound. As the metal reacts with the acid and metal ions fly off into solution, the ions coming off of the bound spring will have a slightly higher speed, on average, than the ions coming off of the unbound spring, because the greater potential energy in the bound spring is a result of the greater repulsive forces between atoms in that spring, bound into an unfavorable configuration. The average speed of atoms in a liquid which has no overall velocity correlates with the heat energy of the liquid. Chuck 23:28, 8 February 2006 (UTC)[reply]

Wow, that's a nice analysis Chuck! deeptrivia (talk) 01:32, 12 February 2006 (UTC)[reply]

Metal: Swords and Armor

what metal would make for a superior sword with the characteristics of being super strong, keeping an edge, and excelling in the art of batte ie:sword fighting,dueling, ect. im curious what would make for a superior sword, such as titanium? or animantium(im not sure if it is superior in anyway, im not to sure about animantium in any way shape or form? or steel? or any metals that are out there.

what type of metal would make for light, yet superior in strength and durability armor, ie: bullet proof, sword,knife,club, spike proof, things of that nature.

I don't think you can beat a good steel for its ability to hold an edge, yet still be flexible. Katana are made by folding steel many times to remove impurities and then cooling it slowly in layers of mud. Titanium alloys are popular because they are strong and light, but they would be impractical for swords, as discussed here: http://swordforum.com/metallurgy/titanium.html. I assume "animantium" is a misspelling of adamantium, a fictional material. —Keenan Pepper 01:43, 9 February 2006 (UTC)[reply]

Plus it'd be hard to lop off someones head with a sword made out of ultra-light metal (unless it was super-thin as well). freshgavin TALK 02:55, 9 February 2006 (UTC)[reply]

Be sure to take these items to your local church and have them properly blessed to decrease your armor class and THAC0 before LARPing! KWH 03:38, 9 February 2006 (UTC)[reply]

Of course, regular steel can rust, so needs to be cleaned and oiled after each use, to prevent this. StuRat 05:23, 9 February 2006 (UTC)[reply]

Whichever metal (or metals) you use, it is advisable to give differnt parts of the sword different characteristics. For example, if you use iron, lots of carbon and big crystals (as in cast iron) make for a very hard, but brittle material. Less carbon and small crystals (such as steel) is stronger but dents more easily. So a good combination will be to have the 'body' made of steel for strength and the cutting edge(s) hardened (eg by rapid cooling). The method used by the Dayak is to use a separate hardened strip for the cutting edge. See also Dayak#Society (I wrote that bit :) ).

Having said that, an ideal cutting edge would be diamond, I presume, and I believe such knives actually exist. It only needs to be a very thin layer and diamond is starting to be made industrially, so that wouldn't need to be as expensive as it sounds. You ask specifically for a metal, though, but I presume that that was not deliberate, just inspired by what you're used to. Free your mind! (and your donkey will follow...). DirkvdM 12:54, 9 February 2006 (UTC)[reply]

thats great, now how about for the armor part? metals for armor and the fabric for underneath, any ideas on that?

In high-school I made a chain-mail glove out of steel wire bent into 1cm ringlets for a history project. The one glove (fingers and thumb) took almost 4 months to finish, and my hands smelled like rust for the rest of the year. I got bad on the project because I didn't spend any time on the actual report. It was quite heavy and because of the size of the ringlets a little bit uncomfortable to wear. freshgavin TALK 03:25, 10 February 2006 (UTC)[reply]

And that's just one glove. Now you can imagine why only knights had chain mail suits. They were incredibly expensive (took one person months to make).

But again, why would it have to be metal? Bulletproof vests are made of cloth. I haven't read the whole article, but it doesn't seem to say anything about protection from anything other than bullets. I wonder if the slicing movement of a sword (as opposed to a blow) would cut through them. DirkvdM 08:24, 10 February 2006 (UTC)[reply]

I'm pretty sure a sword wouldn't be able to cut through something like Teflar, because of the elasticity of it, but a good blow to the chest would still probably be fatal, smashing your ribs and piercing your lungs and heart. freshgavin TALK 02:50, 13 February 2006 (UTC)[reply]

Off the top of my head I would say a Titanium sword with a Tungsten Carbide edge, since no one said modern materials were forbidden. I don't think a sword would work very well against Kevlar (I assme this is the 'cloth' you are talking about) I recall an article years ago (an older version of Kevlar) where a police officer was attacked with an icepick and it did not

go through.

Did you see the link above that discusses why titanium would be a poor choice for a sword? —Keenan Pepper 05:27, 11 February 2006 (UTC)[reply]

There are actually modern gloves designed for cops and correctional officers to wear that are specifically designed to resist attacks from knives, such as slicing or piercing, which is significantly different from what it takes to stop a bullet. A bulletproof vest can still be cut by a good sword or stabbed through by a narrow one, what you need is a more tightly woven fabric that's purpose made for cut resistance. Steel mesh is still used in this area, too, but it's much easier to make than chain mail. Night Gyr 10:57, 14 February 2006 (UTC)[reply]

Question about rocks

I am having trouble finding which rock is used to make building blocks, cement, and fertilizers. I can find two of the three uses for many rocks, but not one that does all three.

Hint: limestone --Zeizmic 00:48, 9 February 2006 (UTC)[reply]

That's not a hint, that's an answer. And a correct one at that, I believe. DirkvdM 12:56, 9 February 2006 (UTC)[reply]

I don't think rocks are used to make fertilizer. This is an electrochemical process which makes Ammonia and Nitrates.

February 9

Microscopes/microscopy

What is the definition of the "lens field" when referring to microscopes. Thank you68.106.127.212 00:19, 9 February 2006 (UTC)[reply]

I think lens field refers to the disk of light that you see when you look into the microscope (with the lamp lit of course). The diameter of the disk becomes smaller, the more powerful magnification lens you use. - Cybergoth 03:00, 9 February 2006 (UTC)[reply]

For instance, in urinalysis microscopy reports, the white or red blood cell count is reported in "number of cells/hpf" (where "/hpf" means "per high power field), meaning the number of cells seen in the lens field using the highest power magnifying lens. See microscope. - Cybergoth 03:04, 9 February 2006 (UTC)[reply]

Why would the lamp have to be lit? My microscope has a mirror and I prefer to take it to the window and use that big lamp up in the sky. DirkvdM 13:00, 9 February 2006 (UTC)[reply]

In my limited experience with microscopes, I have not used one equipped with a mirror. - Cybergoth 23:07, 9 February 2006 (UTC)[reply]

Maybe you mean field of view? DirkvdM 13:00, 9 February 2006 (UTC)[reply]

I have gills

They help me breath air under water

You might be interested in the chapter of "As I Lay Dying", by William Faulkner, repeated, in it's entirety, here:

"My mother is a fish."

Could you be related ? StuRat 05:19, 9 February 2006 (UTC)[reply]

I have a sense of humour... it helps me find statements like this somewhat funny, but you coul've done better.--Cosmic girl 03:24, 9 February 2006 (UTC)[reply]

Where is the question? The reference desk is for asking questions. —Keenan Pepper 05:19, 9 February 2006 (UTC)[reply]

If you're human, then gills probably will not be sufficient for you to remain underwater—I believe the oxygen content of water is insufficient to meet a human's needs (and probably insufficient to meet a homeothermic (warm-blooded) mammal's needs in general. Dolphins (that's what I am) must return to the surface to breathe; the low oxygen content of water is almost certainly not sufficient to supply a brain capable of writing sentences. — Knowledge Seeker দ 05:30, 9 February 2006 (UTC)[reply]

If you have lots of gills, you could drink like a fish. There several gills in a pint. Grutness...wha? 05:45, 9 February 2006 (UTC)[reply]

Some fish are bigger than humans (in the case of the whale shark that's a bit of an understatement) and they can 'breathe' under water, so why couldn't humans? Another question is how likely it would be for humans to develop gills (again). Anything stopping us? DirkvdM 13:04, 9 February 2006 (UTC)[reply]

When did humans ever have gills? :S ... when 'we' had them I think we where far from human... hehe, it would be funny to see a hominid with gills...poor hominid, there's no doubt I'd bully him about his gills all day.--Cosmic girl 16:55, 9 February 2006 (UTC)[reply]

You might want to see the film Waterworld then. DirkvdM 19:41, 9 February 2006 (UTC)[reply]

The brain-oxygen point is an interesting one. This site has a nice graph of brain-size to bodyweight, though I'm not quite sure what it tells you. The whale shark's brain is about a metre long, but I don't know if a brain's oxygen consumption is relative to its size. Mark ^{your words} 14:33, 9 February 2006 (UTC)[reply]

Hmm, yes, humans have a very high brain-tobody-weight ratio and the brain uses a lot of energy/oxygen (well, in humans, at least...). But the size difference between humans and whale sharks is so great that that would easily counterbalance that argument. But now I notice I haven't read Knowledge Seeker's posting well enough. He points out that we are warmblooded and therefore need much more energy. And that's a strong argument. Maybe if we stayed very 'cool' we could manage. Surfers consider themselves to be a bunch of cool dudes, I believe, and they already spend most of their time in/on the water, so maybe if we give them, oh, say, 100.000 years or so they'll develop gills. Unless we genetically engineer them, that is. After all, we carry the gill-genes with us, our ancestors being fish and all. They managed to switch from gills to lungs, so why couldn't we reverse that? DirkvdM 15:40, 9 February 2006 (UTC)[reply]

H5N2

I heard in TV that the H5N2 aka "avian-influenza-the-serial-killer" was created by humans, mainly cause theres no virus in the whole world that evolves in such form. Is this true? AFAIK the H5N2 was first discovered in China, n we all know the Chinese re havin problems with that overwhelming population. Ok this possibly sounds a bit psychotic or like a conspiracy theory, but WHAT'S GOIN ON???

The same thing was said about HIV ... I actually don't think that's what happened since if I believed that, I'd have reasons to be paranoid of everything... and I'm a person that tends to be a little paranoid sometimes ... I'd dissmiss that idea if I was you, but who knows! oh and also I don't think so, since it would also mean danger to the people that created the virus...and financial losses for basically the whole world. just out of curiosity...did they say 'on tv' WHY would humans wanna create such a virus?--Cosmic girl 03:33, 9 February 2006 (UTC)[reply]

I think she's onto us. You know what to do... --JianLi 03:43, 9 February 2006 (UTC)[reply]

lol i'm not against Chinese people they're wonderful n so intelligent (take the Great Wall as an example) but it's a possible theory, just imagine: the pop problem in China is solved, n the Chinese government gains lot a money 'cause other nations re affected n they need lots of medicines

It's not at all uncommon - in fact, it's expected - that new varieties of influenza will be discovered first in or around China, presumably for reasons of sanitation and the fact that there are vast rural areas where people, swine, and chickens all live in close proximity. - Nunh-huh 03:54, 9 February 2006 (UTC)[reply]

agree, chinese people are awesome...and chinese guys are cute! :O --Cosmic girl 19:22, 9 February 2006 (UTC)[reply]

Wasn't the huge threat H5N1? — Ilyan e p (Talk) 04:05, 9 February 2006 (UTC)[reply]

I'm including both H5N2 and H5N1.

Maybe the Influenza pandemic article will help. --OneEuropeanHeart 04:22, 9 February 2006 (UTC)[reply]

I guess if you reject evolution, it must be the case that entirely new diseases were all created by man. Notinasnaid 09:35, 9 February 2006 (UTC)[reply]

I heard in TV

Usually your first clue that your information should be taken with a grain of salt :-) As for your question, the answer is almost certainly "no" - science is still far from being able to 'create' a virus, we don't even entirely understand how they work yet! Plus, a virus is a lousy population control measure - it has an annoying tendency to mutate from its intended form. Which is probably how H5N1 first emerged, from a different strain of flu virus. — QuantumEleven | (talk) 09:49, 9 February 2006 (UTC)[reply]

I would say "I heard it on TV" could mean the info is reliable or not, depending on if it came from a reputable Science program, like Nova or Scientific American Frontiers or was something said by Geraldo Rivera. Similarly, "I heard some guy say it", could be reliable, if say it came from the Director of the Centers for Disease Control or unreliable if it came from that crazy bum on the corner. For all we know, that crazy bum on the corner might actually be Geraldo Rivera, in which case his credibility would be impeached significantly further. :-) StuRat 18:23, 9 February 2006 (UTC)[reply]

Just because there's "no [other] virus in the whole world that evolves in such form", it doesn't mean the virus can't evolve in such form. Sure, scientists might not yet know how it evolved, but that doesn't mean it has to be made by humans. Many strange living things have been discovered. Are they all made by humans?

By the way, I'm Chinese, and Chinese people aren't more intelligent than the other people in the world. They only appear to be more intelligent in the West because those who are not very intelligent are unlikely to get a high education, and those without a high education are unlikely to get into North America. Also, I.Q. is highly inheritable, so Chinese children might be expected to do better in school. Bowlhover 03:19, 10 February 2006 (UTC)[reply]

You might want to read our article on Race and intelligence, which suggests that asians are indeed, on average, slightly more intelligent — though it's more to do with economic and cultural factors than genetics. GeeJo _{(t) (c)} • 19:56, 15 February 2006 (UTC)[reply]

The pandemic threat is a specific strain of the subtype H5N1 of the species Influenzavirus A (bird flu virus). Its evolution from prior strains is well documented in the on-line documents linked to in the technical sub-section of the H5N1 "Further reading" section. WAS 4.250 05:26, 12 February 2006 (UTC)[reply]

H5N2 caused flu outbreaks with significant spread to numerous farms, resulting in great economic losses in 1983 in Pennsylvania, USA in chickens and turkeys, in 1994 in Mexico in chickens and a minor outbreak in 1997 in Italy in chickens [3]. In China, inactivated H5N2 has been used as a vaccine for H5N1. people.com.cn WAS 4.250 05:26, 12 February 2006 (UTC)[reply]

Neither was made by man in a laboratory. But it is arguable that China's livestock vaccine policies helped H5N1 to evolve into what it is today. WAS 4.250 05:26, 12 February 2006 (UTC)[reply]

Deicers

Hey Wiki Volunteers (right?),

Well, I am a student in high school, and we are doing some interesting things in chemistry. I found something that caught my eye, and decided to search a bit. I was told that if a compound was ionic, it would break up into multiple ions and therefore lower the freezing point depression of water moreso than a molecular compound.

I looked into this, and I found that a compound called Propylene Glycol is a highly used deicer, and works better than a compound such as Calcium Chloride... but Propylene Glycol is molecular (C3H8O2). So why, exactly, is this? I've searched a bit, and maybe I am a bad browser, but I couldn't come up with anything. I am also definately not an experienced chemist, so I could be getting concepts wrong...

I sure hope you guys can help me out--you've done great in the past!

Well, as a general statement that might be correct. I'm not completely sure glycol really is that much better as a an anti-freeze, although it's possible. In any case, one of the main reasons you don't want to use a salt as an anti-freeze is that a high salt concentration helps cause corrosion. (Things rust faster in saltwater) You wouldn't want to put saltwater in your car radiator. Salt is still used for de-icing roads though. Another bonus is that glycol is more environmentally friendly, in soil it breaks down fast, whereas salt will stay around. --BluePlatypus 08:05, 9 February 2006 (UTC)[reply]

For biochemists, it's also much gentler on antibodies and proteins when you freeze them, while salts have all sorts of unwanted side effects. - Mgm|^(talk) 09:37, 9 February 2006 (UTC)[reply]

biochemical comparison

What is an example of a biochemical comparison to identify a species

Many thanks MT

Here is one using PCR:
Identification of mammalian blood meals in mosquitoes by a multiplexed polymerase chain reaction targeting cytochrome B.
--JWSchmidt 18:11, 9 February 2006 (UTC)[reply]

wtf

Sex and Masturbation

Does sex and masturbation lead to loss of energy?

Yes, like any other form of physical exercise. Not that most people are likely to do enough of either to seriously burn calories, although I suppose it's possible. —Ilmari Karonen (talk) 09:36, 9 February 2006 (UTC)[reply]

According to my knowledges, making love one time which costs the energy worthy of riding bicycle in 10 km.--HydrogenSu 14:04, 9 February 2006 (UTC)[reply]

I read that a night's sleep burns about the same energy as having sex once. I can't believe I could ride 10 km with the energy burnt sleeping. --?? | Talk 20:37, 16 February 2006 (UTC)[reply]

And what about making love WHILE riding a bicycle ? StuRat 18:10, 9 February 2006 (UTC)[reply]

With or without a seat? --24.231.16.6 03:41, 11 February 2006 (UTC)[reply]

You'd fall off before you went 10 km. Grutness...wha? 00:04, 10 February 2006 (UTC)[reply]

Not necessarily. I saw, somewhere, a clip of a naked guy and girl riding a motorcycle down a racetrack, in a curious position, while doing a wheelie. It was, to say the least, impressive. With training, it could be possible to do that for 10k on a bike. Black Carrot 01:25, 10 February 2006 (UTC)[reply]

The British national health service is now recommending that people get fit by having sex: [4]. Mark ^{your words} 11:12, 11 February 2006 (UTC)[reply]

It Burns enough calories and you use enought energy to lose one pound while doing it. (at least in my case)

A large chunk of that is probably perspiration. Mat 11:34, 15 February 2006 (UTC)[reply]

science

Hello

I'm trying to figure out how insects like spiders go up over the walls against gravity??

They climb, just like a rock climber climbs against gravity. When you're the size of a spider, an apparently smooth wall has plenty to hang onto, and spiders can be pretty reckless because falling won't hurt them. (By the way spiders aren't insects, because they have 8 legs instead of 6, but the same applies to insects). Notinasnaid 10:34, 9 February 2006 (UTC)[reply]

Certain spiders and insects also have climbing aids of various sorts, such as claws on their feet, or little sticky pads to help them cling to walls or even ceilings. — QuantumEleven | (talk) 12:17, 9 February 2006 (UTC)[reply]

I've heard cockroaches have static charges on their feet that help them cling. 205.196.208.20 13:11, 9 February 2006 (UTC)[reply]

I love researching weird stuff, and this [5] deserves an article. Any of our enthusiastic noobs want to do it? --Zeizmic 15:40, 9 February 2006 (UTC)[reply]

The ability to climb is very much related to the scale of an organism. The weight of an insect or arachnid is almost insignificant compared to other forces, like adhesion. At the scale of people, it's the other way around, and the weight is the most significant force. When you get up to the size of an elephant, climbing becomes completely impossible. StuRat 18:01, 9 February 2006 (UTC)[reply]

If you actually believe all that mumbo-jumbo about "forces", then how do you explain Spiderman? freshgavin TALK 03:18, 10 February 2006 (UTC)[reply]

He uses cobweb, which makes some sense, because that is a very strong material. Much stronger than steel per weight, so you can use very long lines without them getting too heavy (and thus having to be extra thick to support themselves, etc). DirkvdM 08:31, 10 February 2006 (UTC)[reply]

Right, but even without cobweb (like when his canister runs out) he can still climb upside-down and stuff, just like a spider. freshgavin TALK 02:52, 13 February 2006 (UTC)[reply]

That's because he's got magic mutant mumbo-jumbo super spider powers (and a silly spandex costume). So he can do anything the scriptwriters say he can do. Q.E.D. —Ilmari Karonen (talk) 12:17, 15 February 2006 (UTC)[reply]

Techs For This Formula

I found some techs on my draw paper which can derive this Solid-Physics formula in easy ways. Not need to truely do by ${\mathcal {\,}}\Gamma (v)\,$ .

N(v)=4{\pi }v^{2}N_{o}({\frac {m}{2{\pi }kT}})^{(3/2)}e^{-mv^{2}/2kT}

Where

{\mathcal {\,}}v\,

:velocity in circle-speed distribution

{\mathcal {\,}}N\,

:State-Numbers

{\mathcal {\,}}N_{o}\,

:Original State-Numbers

{\mathcal {\,}}k\,

:Boltzmann constant

--HydrogenSu 11:20, 9 February 2006 (UTC)[reply]

What you have here is the Maxwell-Boltzmann distribution give or take a few constants. --HappyCamper 20:00, 10 February 2006 (UTC)[reply]

Why that formula can be used to solve Maxwell speed distribution? As the below:

{\mathcal {\,}}N(E)={\frac {2{\pi }N_{o}}{({\pi }kT)^{3/2}}}E^{1/2}e^{E/kT}\,

-Curiosity--HydrogenSu 19:46, 12 February 2006 (UTC)[reply]

Plank's Theory did not involve "photons" but "phonons"

For the previous discussion, the Plank's S.H.O. energy shows as:

E={\frac {h\nu }{e^{h{\nu }/kT}-1}}

I was back to read that part of my textbook. Actually

{\mathcal {\,}}h\nu \,

in Plank's that year deriviation,it represented as Simple Harmonic Oscillators'(like"phonons") vibrating energy,not as photons' energy.--HydrogenSu 10:42, 9 February 2006 (UTC)[reply]

I'm pretty sure Planck set out to solve the ultraviolet catastrophe, so it was indeed photons he was thinking of. You can actually model either photons or phonons as Harmonic oscillators—I believe they obey the same differential equations, except for the constants being different. -- SCZenz 17:19, 9 February 2006 (UTC)[reply]

?...????? ?????????????????????. ?????????! ?????,???.--HydrogenSu 10:35, 10 February 2006 (UTC)[reply]

Any E field and M field ??????????? ???2???? ???2?modes. ??????? ????deriviation ??2.--HydrogenSu 10:51, 10 February 2006 (UTC)[reply]

I'm really sorry, we'll find it hard to help you if you post in Chinese. enochlau (talk) 13:08, 10 February 2006 (UTC)[reply]

Sorry. Let me translate in English. I think Plank's

E=n{\hbar }\omega

which refered to S.H.O. energies. But Einstein's

{\mathcal {\,}}E=h\nu \,

which refers to a photon energy(none any -s).

Afterall and finally they're not the same. It's said by my professor. I guess what user SCZ meant was some scientists in 20th century or now might get some theories to combine them together. Maybye. How do you think? (What I need are "thoughts" not answers "truely".)--HydrogenSu 18:49, 10 February 2006 (UTC)--HydrogenSu 18:53, 10 February 2006 (UTC)[reply]

The expressions are really the same thing...except that the factor of two pi is associated with different quantities. Planck's constant can be thought of a "Joules per hertz", meaning the amount of energy that is in a photon that has a frequency of 1 hertz. The reduced Planck's constant can be thought of as "Joules per hertz per radians" - more useful when you are dealing with angular momentum. --HappyCamper 19:55, 10 February 2006 (UTC)[reply]

Let me translate the Chinese for everyone...My very imprecise translation attempt: "?...????? ?????????????????????. ?????????! ?????,???." says something to the effect "It is my inclination that we should be using even newer techniques and theories to explain the theories of the past. There isn't a scientist who knows everything, and everyone knows that."

Hmmm..... I feel I'd better once again translate it,also am for responsible. :) --I personaly think that it(what the User:SCZ meant)should be using even newer techniques and theories to explain the theories of the past. There isn't a scientist who knows everything,they are not God(s) afterall.---My originality in both words and the Chinese. --HydrogenSu 19:46, 11 February 2006 (UTC)[reply]

"Any E field and M field ??????????? ???2???? ???2?modes. ??????? ????deriviation ??2" - "Light consists of an electric field and a magnetic field. Hence, light has at least two degrees of freedom, or two modes. Hence in the derivation for the blackbody radiation, a factor of 2 is present."

What factor of 2? This doesn't ring a bell, although it might be something specific to the derivation procedure...Well, the translation isn't perfect, but at least it's a reasonable attempt I think :-) --HappyCamper 19:55, 10 February 2006 (UTC)[reply]

There was possible in that time and years of Einstein and Plancks. I mean they were relationships of teacher and student. I read a "comics" made by a Japanese. Planck one day went to "class" Einstein's S.R. . All students went away when S.R. started,but Planck stayed only. Wouldn't they discuss together on "Photons" then exchanged each other views of Physics? But this happened after Einstein published his photon theory. So in some views,it would be impossible.--HydrogenSu 12:38, 11 February 2006 (UTC)[reply]

Pets

I have pets,they're fishes. Everytime I call them come by shaking my hand(s),they'll do. Why? Curiosity...Do they "feel" my existance? If they do,why do they seem to "don't know of me" when I am back home? --HydrogenSu 11:43, 9 February 2006 (UTC)[reply]

I have a tank full of fish, too. They shake their heads at me when I post a poorly formed question. --Zeizmic 13:13, 9 February 2006 (UTC)[reply]

Presumably they think you're about to feed them. --Shantavira 15:12, 9 February 2006 (UTC)[reply]

They don't be afraid if I want to "kill" them? Must be both afraid and expectable in their "mind" ,mustn't they?--HydrogenSu 15:37, 9 February 2006 (UTC)[reply]

I go with the feeding theory. They have learned that a certain series of images and sounds comes right before they are fed, so they move into position to be sure they get the food. You could arrange a system where Beethoven is played right before a robotic arm dumps their food into the container, and they would react in the same way ("A Fishbowl Orange" ?). StuRat 17:43, 9 February 2006 (UTC)[reply]

Perhaps the name Ivan Pavlov rings a bell? Check out some of the classical conditioning-related links associated with him and you might find the answers. Grutness...wha? 00:09, 10 February 2006 (UTC)[reply]

I am drooling with anticipation at reading that article. StuRat 10:55, 10 February 2006 (UTC)[reply]

Yeah, but fish have really tiny brains, wouldn't you need some sort of long term memory in order for pavlovian stimulus to be possible?--64.12.116.74 02:22, 10 February 2006 (UTC)[reply]

Well, I wouldn't expect them to memorize the periodic table anytime soon, no, but memorizing the conditions where food can be found is absolutely critical to their survival, so gets a considerable portion of their tiny brains devoted to it. StuRat 10:52, 10 February 2006 (UTC)[reply]

There's a common misconception that fish can't see outside the bounds of their fishtank because of refraction. If you look into a fishtank from the top, it appears as if the inner-side of the tank is a mirror and so that's where the misunderstanding comes from. Looking outside the tank from inside the water changes the angle of refraction, and thus, the fish can see you as well as you can see them, assuming they're looking and the actually care. I agree with Shantavaria in that they probably see something coming and assume it's just the God of food. Try walking up to them and waving them away saying "RUN AWAY! I'm going to KILL you!". There's a very good chance they would treat you exactly the same way as if you were shaking your hands at them. freshgavin TALK 03:12, 10 February 2006 (UTC)[reply]

There is an old saying that "a gold fish has a three second memory." MythBusters tested this one. Verdict: not true. Fish do remember stuff for at least several weeks. The guys from MythBusters made simple mazes for their fish. Years ago, I saw a much more complicated fish maze. Fish would congregate at one particular place in the "tank-maze" just at feeding time. And they would respond to a cue to go somewhere else in the maze for feeding at "surprize feedings". The really neat thing about this is that every few weeks you could change the feeding place, and the fish would relearn the new location. Co-ol, no?

With limited memory, it would make sense to recall less detail, not to strictly limit memory to the last few things done. For example, if a red and green striped fish tried to eat the goldfish, it would be very worthwhile to remember that for next time. On the other hand, I've seen them repeatedly swallow and spit out the same turd, so they apparently don't recall that they just tried it a few seconds ago. I suppose there isn't much value to remembering that. Of course, while people can recall things from decades ago, we are only likely to recall a few critical items. Can you recall what you had for breakfast on July 13th, 1997 ? Probably not. StuRat 05:01, 12 February 2006 (UTC)[reply]

Maybe fish are just ignorant idealists, and choose only to remember things that please them. freshgavin TALK 02:54, 13 February 2006 (UTC)[reply]

Measuring time in PHP

Is it possible to design a test in PHP (or similar web language) that can measure the time taken to make responses? If so, how accurate can this measure be (miliseconds?)? Thank you very much!

A little research shows that maybe the microtime() function would help me, but I'm worried about "This function is only available on operating systems that support the gettimeofday() system call.". I want this to work on anyone's computer, and also to be client-side (I think) so as not to deal with delays in getting to the server(?). Will microtime work, or is there a better solution?

If you want it to be client side, you should use javascript for this. I don't know the precise functions but I'm sure there is a way to do it. --Fastfission 21:19, 9 February 2006 (UTC)[reply]

As in the time taken for the server to hand out a page? Or the time a user takes to make a response on the page? The former would require PHP, while the latter could be done with JavaScript. It would involve setting a Date object in JavaScript at one point in time and checking it later. If you need more help, you can give me more details on my talk page and I can try work something out. -- Daverocks (talk) 22:39, 9 February 2006 (UTC)[reply]

Physicists agree that real-time methodologies are an interesting new topic in the field of cryptoanalysis, and steganographers concur. Furthermore, this is a direct result of the refinement of the Turing machine. Continuing with this rationale, on the other hand, a significant issue in wireless machine learning is the construction of wireless archetypes. Contrarily, forward-error correction alone cannot fulfill the need for collaborative algorithms.

We question the need for the development of write-back caches. Two properties make this solution perfect: our methodology is based on the structured unification of red-black trees and SCSI disks, and also Mashy synthesizes linear-time algorithms. Unfortunately, read-write communication might not be the panacea that security experts expected. Our aim here is to set the record straight. Even though such a claim might seem perverse, it has ample historical precedence. The basic tenet of this solution is the improvement of congestion control. The flaw of this type of method, however, is that voice-over-IP and von Neumann machines can synchronize to fix this question.

Our focus in this work is not on whether the foremost lossless algorithm for the analysis of DHCP by W. Smith et al. is NP-complete, but rather on proposing a cacheable tool for studying hierarchical databases (Mashy). We emphasize that Mashy requests mobile symmetries. In the opinion of futurists, our methodology explores Smalltalk. as a result, our application investigates pseudorandom modalities.

Here, we make three main contributions. To begin with, we construct a novel method for the exploration of Internet QoS (Mashy), which we use to disconfirm that web browsers and interrupts are continuously incompatible. We use symbiotic technology to verify that the much-touted relational algorithm for the technical unification of voice-over-IP and interrupts by U. Sato runs in W(logn) time. We introduce new cooperative theory (Mashy), confirming that the memory bus [20] and the Ethernet are generally incompatible.

The roadmap of the paper is as follows. We motivate the need for model checking. Second, to solve this quagmire, we show not only that the foremost read-write algorithm for the simulation of telephony [20] runs in W( n ) time, but that the same is true for DHTs. As a result, we conclude.

What causes the shock? simple question

Why is it when you get from metal when a small peice of foil is in between your teeth. i cant recall from chemistry, it was discussed. what does the metal conduct for it to be electricty? thank you for your response.

Oh I hate that! Never pull the foil off a beer with your teeth! Hint: Electrochemistry --Zeizmic 15:43, 9 February 2006 (UTC)[reply]

I believe that this only occurs if you have fillings. — Asbestos | Talk (RFC) 15:56, 9 February 2006 (UTC)[reply]

I think whenever you have moving pieces of metal there will be small electrical charge imbalances and thus tiny sparks. The diff is that the root of a tooth is much more sensitive to this type of thing than the skin, so a person with fillings which conduct the spark to the root with feel it more. Now, why exactly are the roots of teeth so darned sensitive ? I suppose if a caveman was biting something hard that was about to crack a tooth, it was of critical importance to their survival to stop before the tooth cracked. A cracked tooth might have been a death sentence before their were dentists to stop infection and abscess from occurring. StuRat 17:28, 9 February 2006 (UTC)[reply]

As Asbestos indicated above, this occurs only if you have metallic fillings in your teeth. The phenomenon is known as "galvanism", in which two dissimilar metals in an electrolytic solution form a miniature galvanic cell, which generates a small electrical potential within the tooth. The sensitive dental pulp responds to an electric current in the only way it can-- with pain. This is why dentists will not place, for example, a silver filling on a tooth that opposes a gold crown. (The sensitivity of the pulp to electrical current makes it possible to test the vitality of the tooth by means of a device that applies an alternating potential; a failure to respond indicates pulpal death.) By the way, the sensitivity of a tooth to biting pressure is not mediated by the pulp, but rather by pressure receptors in the periodontal ligament. This mechanism does not only come into play when encountering a hard object in food; it informs a sensori-motor loop that modulates the muscular contraction during chewing food of all textures so that an amount of chewing force is applied that is appropriate to the task.--Mark Bornfeld DDS 20:25, 9 February 2006 (UTC)[reply]

Photons? Photon(s)?

I knew that the word "photon" was from Greek. It happened yesterday. And my misconception was from what Einstein called Light-act-particle-like in 1905. He first was a Germany in his life. "He called it "photon" " - where I was wrong in. So if photon "were" from German. --HydrogenSu 18:42, 11 February 2006 (UTC)--HydrogenSu 18:46, 11 February 2006 (UTC)[reply]

I think the letter "s" does not need to be in "photons". Which the vocabulary is from German originally. In German, s/es might not be always added in the end to show it is plural. But in English,must be added in most cased. I'm not sure still. My mother-language is Chinese. We shoud respect German in "photon"? How about? Anyone here is able to be good at German? I'd just learned for several months. Listing:

English VS. German

lampes VS.

{\mathcal {\,}}Lampen\,

teachersVS. die

{\mathcal {\,}}Lerhrer\,

--HydrogenSu 17:11, 9 February 2006 (UTC)[reply]

In English, the plural of "photon" is definitely "photons". It doesn't really matter whether it comes from German, but in fact it doesn't—it's "modern ancient Greek", you might say (analogous to "modern Latin"). The ancient Greek plural, I think, would be "phota", but noboday says that. --Trovatore 17:13, 9 February 2006 (UTC)[reply]

There are millions of words in English that have come from another language initially. Probably most of the words in the English language. However, when a word has been firmly established as an "English word," we don't defer to the etymology for deciding how to form plurals. In English, it is correct to speak of one photon, or many photons. If you'd like to have some fun, however, go over to the Language desk and ask about the plural of "index." LarryMac 17:15, 9 February 2006 (UTC)[reply]

English is a Germanic language, but most English words do not come from German. More words come from French and Latin. In third place, about a quarter of the words are Germanic, which doesn't necessarily mean they come from German. Secondly, "photon" is not from German. Third, German doesn't use "-s" as a plural form most of the time. It uses -en/-er (and many others). Fourth, why would you want introduce foreign grammar? That is almost never done, and certainly never done for the German words which already exist in English. Fifth, you should probably master English grammar before suggesting changes to it. --BluePlatypus 17:32, 9 February 2006 (UTC)[reply]

Photon is not German. While Germans may have helped discover photons, the word is based on the Greek "Phos" or "Photo" (light), with -on added to the end to indicate that it is a sub-atomic particle (like protons, neutrons, electrons, boson and so on). smurrayinchester^{(User), (Talk)} 17:56, 9 February 2006 (UTC)[reply]

LarryMac, you mention index, and there are lots of other exceptions too, eg. criterion > criteria and phenomenon > phenomena. These were borrowed from Greek, but are now firmly established as English words. Nevertheless, anybody saying "phenonemons" or "criterions" would need to be prepared for a bit of flak. JackofOz 22:04, 9 February 2006 (UTC)[reply]

Hi Jack. (OK, I've been dying to say that. Sorry.) I chose "index" simply because I have been exposed to many instances of "indexes;" however I think that version is correct when discussing, for example, more than one index on a table in a database. It still bothers my ear, though. I'm getting way too old. --LarryMac 01:30, 10 February 2006 (UTC)[reply]

(I get 'hijack' all the time.) Apparently indexes is considered correct these days. What I want to know is, why weren't we elder statespersons consulted on this? JackofOz 02:30, 10 February 2006 (UTC)[reply]

'tis worth mentioning possibly that - while photon is not German, we do use the German -en ending for one or two odd words that have entered the englsh language from German - or more sofrom its earlier relations like Saxon. The commones of these are probably child/children and ox/oxen. And I'm with you on indices, Jack, although I'm pedantic enough to confuse people by using plural terms like Eisteddfodau. Grutness...wha? 04:56, 10 February 2006 (UTC)[reply]

Thank you all. Merci. My "wife-language" is French. Je maitenant sais que "photon" n'est pas de German mais est du français. Et il a quelq'uen sait que qulques choses des "photons" avec Eintein? Si il peut senaître,parler en tout à mois. S'il vous plaît. --HydrogenSu 09:43, 10 February 2006 (UTC)[reply]

My French isn't good enough to reply in kind, but I must correct you: as people have mentioned above, the word "photon" comes from the Greek, not from the French as you are now saying. The first line of the photon article makes this clear: "Photon (from Greek f??, "phos", meaning light)." It has the same root as phosphorus, for that matter, which is also not from the French (nor the German). — Asbestos | Talk (RFC) 19:07, 10 February 2006 (UTC)[reply]

Herceptin

What part of the HER-2 protein does Herceptin bind to?

Please use the search box at the left side of this page before asking a question here. Our article on Herceptin discusses this (see the 'Mechanism' section.) TenOfAllTrades(talk) 20:45, 9 February 2006 (UTC)[reply]

Metals and heat treatment

Why does quenching only work for steel? How can I harden wrought iron, brass, etc.? Ksenon 19:37, 9 February 2006 (UTC)[reply]

I believe quenching works for many metals. I believe I've both hardened and annealed copper, for example. The quench article is a stub, and (if I'm right about other metals) I'd say it's misleading the way it mentions only steel. --Steve Summit (talk) 00:44, 10 February 2006 (UTC)[reply]

Actually, you can also quench fluorescent probes when they're in a high enough concentration among other things. - Mgm|^(talk) 08:39, 10 February 2006 (UTC)[reply]

electromagnetic spectrum

is electric power frequency (50Hz or 60Hz ) included in the electromagnetic spectrum. please explain with chart if so.thanks in advance. 210.56.6.114 21:28, 9 February 2006 (UTC)[reply]

Have you checked our articles on the electromagnetic spectrum and the accompanying super low frequency band? — Lomn Talk 21:35, 9 February 2006 (UTC)[reply]

I had understood that electricity emits em radiation (the supposed danger of living under a high power line), but now it turns out it is em radiation. Or is the word 'radiation' in place here? I have a hard time placing this. I thought electromagnetism was a form of energy in the form of radiation. But electricity is movement of electrons, in other words, it's a capacity or state of matter (what is the right word here). Only when you alternate it does the frequency come into play. Let me put it this way. If you'd speed up the frequency to around 1 PHz, would it then become visible light? I am ashamed to now realise how little I understand this, one of the four elementary forces of nature. DirkvdM 10:19, 10 February 2006 (UTC)[reply]

AC current emits EM waves because the electrons go back and forth and hence accelerate, which causes EM waves to be emitted. But also, in both AC and DC, what causes the electrons to move is an electric field set up in the wire. For AC, because we have an alternating electric field, there must also be an alternating magnetic field - i.e. we have EM radiation "driving" the electrons. enochlau (talk) 13:07, 10 February 2006 (UTC)[reply]

Dirk, there is a difference between an electromagnetic field and electromagnetic radiation. To illustrate the first one, imagine building a resonant circuit consisting of an inductor, a capacitor and a source of AC. Energy just bounces back and forth between the two components, and hardly any energy is drawn from the AC supply (ideally, just enough to fill the circuit with energy, and then no more). Since the energy remains within the circuit, it follows that it is not being radiated. The power in the circuit is called reactive power, because the voltage is out of phase with the current, so the product of the two (the real power) is zero. You have AC but no EM radiation. The moving electrons create an EM field called an inductive field around the wires, but the energy in the field returns to the circuit every time the current reverses.

If you now replace your resonant circuit with an antenna tuned to the right frequency, most of the energy jumps off the wires and launches into space, and this energy is called EM radiation. Unlike the inductive fields around the resonant circuit, this radiated field never comes back! You can tell that your antenna is radiating because it sucks power out of your power supply. You have to feed energy continuously in to the antenna to replace that which is being radiated. This time, the antenna is consuming real power. If you want to know why antennas radiate and LC circuits don't, you could try reading an article like Why an Antenna Radiates. When the AC frequency is in the petahertz range, atoms themselves becomes antennas, so they radiate light. --Heron 00:00, 11 February 2006 (UTC)[reply]

Dark Matter

There probably isn't an answer to this, given that so little is known about dark matter, but the question is in my head and I need to try. I've seen on the TV (and checked on the article dark matter that galaxies are thought to be 'composed largely of a roughly spherical halo of dark matter with the visible matter concentrated in a disc at the center'. Given as how this dark matter is supposed to interact with atomic matter(and hold the galaxies together), what would happen to something made of ordinary atomic matter is if was removed from a galaxy and placed in open space away from the influence of dark matter? If, somehow, you flew a ship away from a galaxy, would it, and I know this sounds odd, fly apart without the dark matter? Probably not fly apart, but would there be any noticable effect?

Ta! Sabine's Sunbird 22:09, 9 February 2006 (UTC)[reply]

When I get my spaceship working, I'm really going to avoid that dark matter! --Zeizmic 23:39, 9 February 2006 (UTC)[reply]

They've discovered what it is, you know - dark matter is really shed cat fur. Seriously, though, how would a spaceship get into intergalactic spacewithout passing through dark matter and therefore attracting some to it by gravity? Grutness...wha? 00:18, 10 February 2006 (UTC)[reply]

I think your reasoning that dark matter hold matter together is based on the fact that it is assumed that dark matter is contrbuting mass and therefore gravity whcih slows the expandion of the universe. I was not under any understanding that it held matter together, I think that is done by the other three fundamental forces. --Martyman-(talk) 01:39, 10 February 2006 (UTC)[reply]

When people talk about Dark matter holding things together, they are referring to its gravitational contribution to keeping the entire galaxy bound—that is, if it weren't there, stuff on the edges (like our sun) would fly away from the galaxy. Smaller objects, like the solar system or your spaceship, are not held together by dark matter—the former almost entirely by the gravity of the sun, and the latter by the chemical bonds holding the materials of the ship together (and thus ultimately by electromagnetism. Does that help? -- SCZenz 07:39, 10 February 2006 (UTC)[reply]

Yeah, I guess the distinction in my head was a little fuzzy. I just figured that if you removed the force there would be some effect. Thanks.Sabine's Sunbird 08:21, 10 February 2006 (UTC)[reply]

I don't think it's dark matter, but my theory is that there is a substance in the intergalactic voids which repels normal matter. This explains:

The accelerating expansion of the universe.

The arrangement of galaxies roughly on the surfaces of "bubbles", which would each be cells filled with this material.

What keeps galaxies together despite the apparent insufficient mass for gravity to do so.

StuRat 09:52, 10 February 2006 (UTC)[reply]

And you could then call that aether. :) By the way, I hope you haven't forgotten that I have already explained the accelerating expansion of the universe with my alternative to the Big Bang theory. DirkvdM 10:28, 10 February 2006 (UTC)[reply]

Interesting. It explains my first bullet, but not the other two. StuRat 18:58, 11 February 2006 (UTC)[reply]

Well give me a break. Not being a physicist, I'm pretty proud to have found a solution to the first one. And one that no-one else seems to have thought of, for a change. DirkvdM 11:07, 12 February 2006 (UTC)[reply]

How to input POJ (Romanized Taiwanese) to Windows 98 or XP?

I try to use regular keyboard to write POJ onto a microsoft word file but do not know how to do it. Please help. Thanks.-- Robert Wu 2/9/2006

I'm sure there's little programs that let you do it easily, but in the absence of such a program you'd probably be stuck with using either the Windows Character map (Start->Programs->Accessories->System Tools/), or you could even use the links underneath at the bottom of the "Edit Page" special page in Wiki... if you're really desparate. freshgavin TALK 03:01, 10 February 2006 (UTC)[reply]

How recent a version of word? recent versions of word let you select any unicode characters from thier insert symbol dialog and keep a list of the most recently used ones. i belive word also lets you set up shortcut keys. Plugwash 10:45, 11 February 2006 (UTC)[reply]

Crystal

Can a crystal overcharge and cause a massive explosion? (read the article on Edgar Cayce in 'major themes', at the end of the paragraph that talks about Atlantis).--Cosmic girl 22:36, 9 February 2006 (UTC)[reply]

Please, define "charging a crystal". A crystal is just an organized molecular structure. See crystal. ? ?i?ff?? 22:59, 9 February 2006 (UTC)[reply]

I know it's just an organized molecular structure,and I don't know what is meant by 'charging the crystal' in that part of the article, that's why I ask...I don't think such a thing is possible either, but I'd better ask than suspect.--Cosmic girl 23:10, 9 February 2006 (UTC)[reply]

A crystal can store a lot of static electricity, so in that respect, maybe. --PopUpPirate 01:11, 10 February 2006 (UTC)[reply]

but can it actually 'explode'?--Cosmic girl 02:34, 10 February 2006 (UTC)[reply]

To answer the question, pretty much everything that Edgar Cayce had to say was nonsense. TenOfAllTrades(talk) 01:38, 10 February 2006 (UTC)[reply]

To answer the question in another way, all explosions are the result of a substance expanding very rapidly and bursting their container. I don't think electricity passing through a normal crystal can cause anything inside the crystal to expand rapidly. Also, even if crystals can explode, the explosion won't be massive if the crystal itself isn't big. Bowlhover 04:46, 10 February 2006 (UTC)[reply]

~~As well as the fact that there's no container to explode.~~ I guess it's concievable that the crystal could act as a container for itself, but I can't think of how. The best you could expect for is for it to expand and collapse/crumble. freshgavin TALK 05:26, 10 February 2006 (UTC)[reply]

thanks! :) --Cosmic girl 19:38, 10 February 2006 (UTC)[reply]

The Butterfly Effect

"Whether a butterfly's wing beat can cause a tornado is still a central debate of chaos theory. But is is now proven that drawings first published more than four months ago in Denmark have seeded outrage among Muslims from Gaza to Jakarta and embittered believers making their lives in Europe." -Time Magazine, current edition

I don't think the allusion to the butterfly effect makes sense. A butterfly creating a tornado is an example of sensitive dependence on initial conditions. And from common sense, sensitive dependence on initial conditions must exist if one considers the enormous number of factors involved in real-world deterministic systems. So my point is, I don't think there really is any debate about whether or not sensitive dependence on initial conditions exists, as stated by the article. ~~And if there was, it wouldn't be around the butterfly example, since this is merely an illustrative example, not the central doctrine of chaos theory.(oops, ignore this)~~ Am I right in this? --JianLi 00:07, 10 February 2006 (UTC)[reply]

Yeah, and no. You're right that the butterfly effect isn't the theory itself, and this is certainly not the first time anyone ever found proof of sensitive dependence on initial conditions. However, the butterfly effect is way more recognizable than the actual theory, and there is certainly a connection between that and the cartoon that most people wouldn't think of on their own. Black Carrot 01:21, 10 February 2006 (UTC)[reply]

Sorry, I don't think I was clear, so I edited my original question a bit to clarify. My issue with the allusion was not that it didn't make sense in relation to the cartoons.

Rather, my issue is with the line that sensitive dependence on initial conditions is the "central debate of chaos theory." I mean, it is basically the cause of chaos, so I think this characterization as the "central debate of chaos theory" is completely off, right? --JianLi 02:46, 10 February 2006 (UTC)[reply]

I don't see the issue either. Certainly some minor changes to a system can eventually cause massive changes later on. However, I think most minor changes would have no such effect. Also, perhaps if you go far enough ahead in time, the system may "reconverge". For example, if our whole solar system is destined to be sucked into a black hole some day, then what we do may ultimately have no effect (assuming nobody leaves the solar system before this happens). Or, if there is a "big crunch" at the end of time for the universe, nothing that happens anywhere in this universe may ultimately matter. StuRat 04:50, 10 February 2006 (UTC)[reply]

Maybe not to the inhabitants of this universe ... Actually, that raises another question. If there is an assumption that this universe is not necessarily the only one there is, is there a word that means "the sum total of all possible universes"? JackofOz 06:03, 10 February 2006 (UTC)[reply]

Multiverse. ? ?i?ff?? 09:42, 10 February 2006 (UTC)[reply]

Thanks. I had a quick look, but either it's not what I'm after, or it could do with some re-writing. It starts off with "A multiverse (or meta-universe) is the hypothetical set of multiple possible universes ...". Later, "Multiverses have been hypothesized in physics ...", and later still "Multiverses merely shift the problem up one level". These seem to based on the idea of there being multiple multiverses. Whereas, the concept I'm concerned with is, by definition, absolutely unique. There can be only one. JackofOz 11:27, 10 February 2006 (UTC)[reply]

As best I can work it out from searching, 'universe' was by itself created to describe all of everything, so it seems a bit odd to shrink that definition down for the purpose of creating more of them. That's like saying 'body' refers to each limb individually, and then claiming all people really have metabodies. And yeah, I think the 'central debate' thing was just being melodramatic for the sake of a better story. Black Carrot 13:13, 10 February 2006 (UTC)[reply]

Ok, that's the confirmation I was looking for. Thanks. -Jian

Thanks. That was always my understanding of "universe" too. In the real world, terminologies change I guess. Sometimes that's a good thing, but sometimes I really wonder. I mean, if science accepts that there's not 1 universe but godknows how many, and it's necessary to come up with a new word "multiverse" for the totality of all things; then what's to stop science from one day noticing that there's not 1 multiverse but many, and we'll need a further new word for the real totality of all things. This could just go on and on an indefinite number of times, and we'd need an indefinite number of words to describe the increasingly gargantuan space-time-thing in which we're located. Why not just stick with "universe", and subdivide it into as many sub-universes as science needs to explain it all away. JackofOz 13:32, 10 February 2006 (UTC)[reply]

February 10

Visible Radio

Awhile ago, when I was visiting RadioShack, the clerk mentioned something he was trying to do in his spare time: make a radio (which broadcasts electromagnetic waves of a controllable frequency) broadcast a frequency within the range of visible light. Specifically, green. Is this possible? Black Carrot 01:42, 10 February 2006 (UTC)[reply]

While this is possibly theoretically possible, this is still around 600 times higher frequency than can be generated through devices such as a Backward wave oscillator, which produce Terahertz radiation. As you can see from Color, visible light is a much higher frequency again. You can see from Radio frequency that visible light is significantly higher than the standard range of the RF spectrum. So no, I don't believe a clerk from RadioShack would be able to achieve anything close teverytho this. --Martyman-(talk) 02:04, 10 February 2006 (UTC)[reply]

Assuming he could generate high enough frequency, would he need a micrometer/nanometer scale antenna, or would any appropriate metal transmit the visible light? Tzarius 03:25, 10 February 2006 (UTC)[reply]

And what would that look like? Black Carrot 03:33, 10 February 2006 (UTC)[reply]

Hypertechnically, isn't any transmission of audio data via light (like, for example, the laser inside a CD player, or even a fiber optic cable transmitting the data from an MP3) the same thing as the "broadcasting" this RadioShack guy is attempting, except for the issue of distance? And wouldn't it be pretty much impossible to get any distance from light broadcasting beyond line-of-sight anyway? You can hardly get more than a few miles from regular transmitters in the gigahertz range as it is. --Aaron 03:36, 10 February 2006 (UTC)[reply]

Assuming he did find a transister that could switch fast enough (probably a physical impossiblity) and an antenna small enough to tune to the wavelength, then it would probably end up looking like an incredibly low efficiency LED. --Martyman-(talk) 05:52, 10 February 2006 (UTC)[reply]

Not to mention, how far would the transmission go? One of the reasons we use radio is that it isn't affected by stuff like buildings being the way, compared to visible light. I could block a "visible light radio" with a piece of cardboard. Confusing Manifestation 13:29, 10 February 2006 (UTC)[reply]

I did this as a science experiment in High School. It was only good for short range transmissions as I used a penlight for the light source as lasers were spendy back then. I used a reflective square on a rubber membrane to modulate the light beam. Someone would speak into the rubber 'microphone' and it would vibrate, causing the light beam to flutter in sync. A laser could be used nowdays in place of the penlight to give greater range. Oh, and radio IS blocked by buildings, if it is the higher frequency radio.

Visible light is pretty lousy as a transmission frequency, as it gets blocked or scattered by lots of things (anything you can't see through :)) - anything solid, dust, fog, frosted glass... It's one of the reasons that radio works so well, as (low-frequency) radio can pass through many seemingly solid objects, and is also barely scattered by things like rain, dust and fog. See radio, or, for ultra-long-range radio transmission (we are talking billions of light-years), radio astronomy. — QuantumEleven | (talk) 17:19, 10 February 2006 (UTC)[reply]

For the record, my antenna beside me is already emitting a wavelength, even when it is turned off, thanks to the vibrations of the electrons. If I wanted my antenna to emit red light, all I would have to do would be to heat it up to around 1000 degrees. I could go up to white light, but I'm not certain if there would be any way of having it emit green light. — Asbestos | Talk (RFC) 19:45, 10 February 2006 (UTC)[reply]

That just got me thinking...does blackbody radiation ever look green? Are there such things as green stars? I somehow don't think so, but I could be wrong... --HappyCamper 20:19, 10 February 2006 (UTC)[reply]

Surely a green lightbulb would do the job? Gdr 22:14, 10 February 2006 (UTC)[reply]

The way I understand it black body radiation is emmited in a wide range of frequencies the upper edge of which moves upwards as the temperature of the body increases. So the reason that hot things glow red then move on through yellow towards white is that initially the body is only emmiting red wavelengths light as it gets hotter it will emmit pretty much all the visible wavelengths equally and it will look white. If it gets really hot it may be possible for the emmited light to favour the higher frequency end of visible light but there is no way for it to only output a narrow notch of frequencies and appear green. --Martyman-(talk) 04:08, 11 February 2006 (UTC)[reply]

Range of hues for black bodies between 100 and 10,000 K

Blackbody radiation essentially produces all wavelengths, with a distribution that looks somewhat like a bell curve. In visible light, the apparent color varies from red to orange to sky blue, as seen at right. When the dominant wavelength is in the green part of the spectrum, there's enough red and blue light that we see white instead. ‣ᓛᖁ

ᑐ 04:48, 11 February 2006 (UTC)[reply]

(added after edit conflict with Eequor, above.)

Yep, Martyman's explanation is correct; we're limited by the way our eyes perceive light and by the breadth of the blackbody emission spectrum. To take an example from our own backyard, stars actually are very close to ideal blackbodies in the light that they emit; astronomers find this very handy for measuring stellar temperatures. Our own Sun has a surface temperature of 5780 kelvin, which by Wien's law should have a maximum emission at a wavelength of almost exactly 500 nm—a slightly bluish green. Obviously, it doesn't look that colour.

To our eyes, hot objects will go from red, to orange, to yellow, to white, and then eventually to bluish (above about ten thousand degrees kelvin.) TenOfAllTrades(talk) 04:51, 11 February 2006 (UTC)[reply]

intravenous feeding

Was there intravenous feeding of patients in the late 1930s? These would be patients in comas. If not, how did they feed these patients? If there was, what were the instruments that were used, and what was the IV fluid contained in?

This seems to have a reasonable history. Not to sure if it answers all your question though. --Martyman-(talk) 02:56, 10 February 2006 (UTC)[reply]

Didn't someone ask this earlier this week? - Mgm|^(talk) 08:41, 10 February 2006 (UTC)[reply]

Java: New instances of a generic type

I'm trying to build a factory class via an interface, like this:

public interface Factory<T extends BaseObject> {
  public T newInstance();
}

So I implement my interface like this:

public class DefaultFactory<T extends BaseObject> implements Factory<T> {
  public T newInstance() {
    return new T();
  }
}

According to Java theory and practice: Generics gotchas (Construction delays), I should (and in fact do) get a compiler error: Cannot instantiate the type T.

My crappy solution is to pass in a Class<T> as a parameter to the DefaultFactory constructor, call Class.newInstance(), catch any thrown exceptions and throw an Error-based Throwable.

Am I approaching this pattern the wrong way? The purpose is I later plan to combine a custom iterator class (much like the generic Iterator interface), and since the source of data is a database or file (rather than a list), I need to be able to instantiate objects on the fly, rather than pulling them into a list and using the java.util.Iterator class.

--24.231.16.6 03:53, 10 February 2006 (UTC)[reply]

I can't think of a better way to instantiate that. There's a good reason why you can't do new T(), and that's because constructor parameters are not defined by interfaces in Java. All Java knows is that T is a subclass of BaseObject, which may or may not have a constructor that takes no parameters. Although why are you resorting to a factory class for this? If you want an iterator for your file, then give whatever data structure is holding the file a method that returns an iterator. enochlau (talk) 13:00, 10 February 2006 (UTC)[reply]

I'm using a factory method with an interface because another factory class that implements it won't actually create new objects. It will be given one object right off the bat, and whenever the next() method is called in my iterator, it will simply return the same object each time (after loading the object with new values). So if I'm going through a batch of 100,000 elements, where I only need one element at a time and discard previous ones, I reuse the same object. I've noticed a speed increase by "recycling" the object, but still want the ability to generate new objects (hence the interface) at certain times. --131.202.90.23 18:55, 10 February 2006 (UTC)[reply]

The "Medieval Warm Period" and the "Little Ice Age"

Could someone direct me to information relating to the causes and nature of both the "Medieval Warm Period" (AD 890 - 1170) and the "Little Ice Age" (AD 1580 - 1850)?

Such as what environmental factors brought them about and allowed for a return to normal temperaturese? Was their effect mostly localized, or was it global? Etc.

Are you looking for additional information that isn't discussed in the Little Ice Age and Medieval Warm Period articles? All of the questions you posed are already answered about as good as you can expect them to be. freshgavin TALK 05:24, 10 February 2006 (UTC)[reply]

This article compares those to the current cycle. [6] --Zeizmic 13:09, 10 February 2006 (UTC)[reply]

Internet Explorer Removal

Is there any way for me to completely remove Internet Explorer from my Windows XP computer? I use Firefox, and my IE doesn't work anyway (it brings up an error and crashes). And if I need IE for a site that onl allows it, I can allows reinstall a fresh version that works. So I would love to delete it, to free up a little disk space and speed up the computer a tiny bit (I assume it will, because it is integrated with the desktop environment, isn't it?) I don't use Outlook, MSN Explorer, or Windows Messenger, so I don't care if they won't work or are deleted (actually, come to think of it, deleting would actually be nice!) while removing IE. I am familiar with the registry, but I just wanted expert advice before I started deleting any keys that seemed to be associated with IE and messed up my computer. Thanks.

You can't really delete IE so easily because, like you said, it is integrated with Windows XP (on the best symbiosis fashion). It is possible to remove it by hacking the OS, but you're likely to make your system unstable and etc. I'd suggest you to just don't use it or get a program to block its access. ? ?i?ff?? 06:09, 10 February 2006 (UTC)[reply]

"Deleting" IE is difficult. Too many things in Windows XP use it. Many Windows Explorer views use IE to run, and many other programs use IE to display messages, like Norton's "Subscription Expired" message. Also, since IE is so integrated into the system, there are different "levels" of deletion. It's hard to draw a boundary between what's deleting IE and what's deleting the OS. By the way, you might be interested in Removal of Internet Explorer. -- Daverocks (talk) 07:52, 10 February 2006 (UTC)[reply]

I also came to that conclusion, that it is impossible to remove. However, I found that if you just don't use it for the Internet, it comes out to the same. Here's an interesting news item that jives with my experience with the kids: [7] --Zeizmic 13:05, 10 February 2006 (UTC)[reply]

Back with Windows 95, I was able to delete it. I didn't use any uninstaller mechanism, just deleted the directory. It saved some space, but a few parts of it might have still remained in the Windows directory. I don't suppose this would be possible with Windows 98 and higher, as there it's more tightly integrated with the explorer. – b_jonas 18:42, 10 February 2006 (UTC)[reply]

That of course only applies if you insist that Windows work afterwards. If you don't, it's quite easy to remove it together with Windows and install a decent OS. – b_jonas 18:44, 10 February 2006 (UTC)[reply]

By the way, removing IE from any version of Windows other than XP is not meant to be impossible, microsoft provides instructions on how to do it. Also, yeah, delete Windows and install a Linux distro. :D -- Daverocks (talk) 05:23, 12 February 2006 (UTC)[reply]

remove to then run an older version as mentioned in that article isn't the same as really removing. you simply don't want to do that, too many things won't work anymore, windows update as one of the most important ones. Boneyard 11:17, 14 February 2006 (UTC)[reply]

TM MODE & RECTANGULAR WAVEGUIES

For the Below:

According to what I know, "modes" exist in any EM field. Might be 2 modes in E and M content. Maybe you would see Normal mode . Hope my suggestion here will be useful and helpful.--HydrogenSu 17:34, 10 February 2006 (UTC)[reply]

Q.What is TM mode

A:Disappeared--HydrogenSu 13:05, 10 February 2006 (UTC)[reply]

--HydrogenSu 10:37, 10 February 2006 (UTC) --HydrogenSu 12:39, 10 February 2006 (UTC)[reply]

errr... how will you know that the person who asked the question can read chinese? enochlau (talk) 12:50, 10 February 2006 (UTC)[reply]

Then someones hide delete them...--HydrogenSu 13:05, 10 February 2006 (UTC)[reply]

From what I know of Chinese that looked like naughty stuff! I didn't delete, but I'll defend to the death their right to do it. --Zeizmic 15:17, 10 February 2006 (UTC)[reply]

Bingo....No....I mean the person who deleted was me. It won't be pity if I delete any Chinese. --HydrogenSu 19:31, 10 February 2006 (UTC)[reply]

-Ohh..helpful not "helpfull". No need double "l"s. In English,spelling is a little odd. French is more normal and is easier. (Just in spelling of their comparation,not in grammar. And most ways to speak or write French,people often don't feel impolite. I'm serious saying these. I had learned French for about 3 years in language-school of Ursuline:) See[8] )--HydrogenSu 19:56, 11 February 2006 (UTC)--HydrogenSu 20:09, 11 February 2006 (UTC)[reply]

What is its relation to rectangular waveguides with TM mode?

I need help understandin these two topics. I would grateful if i got diagrams too. So if any one could please help me. thanks. Arijit

Vous pouvez voir en [9] ou en [10] Pendent vous allez vu(e), si c’est fini, souvant postez vos nouvelles questions ici.--HydrogenSu 13:05, 10 February 2006 (UTC)[reply]

What exactly does TM stand for? I have been thinking about this all afternoon, but nothing has come up yet. This might be completely unrelated, but is it torsional modes you are thinking of? Take a spring...a signal can be propagated along the spring via translational, longitudinal, and torsional modes of freedom. That is to say, the spring can vibrate along its axis, perpendicular to its axis, or twist along its axis. --HappyCamper 22:09, 10 February 2006 (UTC)[reply]

TM mode = transverse magnetic mode, meaning that there can be a longitudinal electric field along the waveguide. The question is very vague though. In free space you normally only get TEM modes, so the waveguide is what allows there to be TE or TM modes. Not sure what information you were looking for though. — Laura Scudder ☎ 22:16, 10 February 2006 (UTC)[reply]

Light octaves

With all these questions about electromagnetism I remember once reading the following idea in the Dutch Mensa Journal. Visible light varies in frequency from 400 THz to 700 THz, which is almost double. In sound, a doubling of the frequency gives an octave-shift; the note is 'sort of the same'. And indeed, the light at the two ends of the visible spectrum are somewhat similar, both somewhat 'reddish'. If we could see frequencies from, say 100 to 1000 nm would we then perceive light in octaves (in casu just over 3 octaves)? And are there animals that can see such a wide spectrum of light?

One could take this even further. In music, a perfect fifth is a pleasing interval (a consonant), with the higher frequency being 1,5 x the lower frequency. But the nearby diminished fifth is a strong dissonant, very unpleasing, with a ratio of 1:1,4142. In light there is less room for such intervals without stepping out of the visible spectrum, but could one say that the combination of, say, 400 THz and 600 THz is pleasing, whereas the combination of 400 THz and 565,7 THz is displeasing? DirkvdM 10:43, 10 February 2006 (UTC)[reply]

I don't know what this THz thing you're talking about, but looking at the numbers, I think you mean nm? Visible light ranges from approximately 400nm (blue end) to 700nm (red end). Your "octaves" argument doesn't really stack up, I don't think. While you can say that the violet part of the spectrum is "reddish", you can also say that the yellow part, or the green part are also "reddish". enochlau (talk) 12:54, 10 February 2006 (UTC)[reply]

To answer to Enochlau, THz is Terraherz, a measure of the frequency of the light in question (which is related to the wavelength by the speed of light). Admittedly, we tend to use frequency for sound and wavelength for light, but given the known speed of wave propagation, either measure is acceptable for either wave.

To Dirk: I would imagine that the concept of perceiving an octave as particularly pleasing is an artefact of how our ears work - our eyes work in very different ways. Also, the visual spectrum is too small to accomodate an entire 'octave' - 400 THz is near infrared, and 800 THz is near ultraviolet. Taking your analogy of an 'octave' further, a quadrupling of the frequency (two octaves) also means the two sounds have something in common, yet, if you quadruple an e/m frequency, you can end up with waves which have very little do with each other, as they are quite far apart in the e/m spectrum. For instance, quadruple in frequency some middle infrared radiation and you end up in the near UV spectrum. My guess is that you just can't apply the same principles to sound as to light. — QuantumEleven | (talk) 17:14, 10 February 2006 (UTC)[reply]

I agree. Ears work by basically doing Fourier analysis on the air pressure varations. Eyes are very different; they project the infinite-dimensional space of spectra onto the three dimensional space (in the case of trichromats) of responses of the three kinds of cone cells. It is easy to tell a single pure pitch from a group of closely spaced pitches, but impossible to tell one pure wavelength of light from a group of closely spaced wavelengths. —Keenan Pepper 19:16, 10 February 2006 (UTC)[reply]

That last bit sounds convincing. A slight difference in light frequency is not noticeable, whilst a similarly small difference in sound frequency (around 1%) is. But, just like with sound, if two colours are discernible, but close in frequency, they 'clash' (is that the right word?), rather like sounds with frequencies that are 10% apart (major second - see interval) are dissonant.

Of course there is no fourier analysis to detect a light octave because the eyes don't register a wide enough range. I don't know if it would make sense for the smaller intervals. But this raises the question why such analysis is done with sound. It gives us the ability to appreciate music, but that can hardly be the purpose (or can it?), so it would have to be a pleasant 'after-effect'. What evolutionary advantage would this give? What is the use of doing a fourier analysis on sound and is that use not present in light? DirkvdM 14:23, 11 February 2006 (UTC)[reply]

Ah. I think this might be the answer you're looking for: If you have one pitch at 440 Hz and another at 442 Hz, they interfere to produce a combination tone at 2 Hz, which is of course not perceptible as a 2 Hz tone but as a beat that repeats twice a second. Many integer ratios can be tuned by eliminating this beat. With light, if you have a 500 THz color and a 502 THz color, the interference is at 2 THz, which is totally imperceptible, so the clashing of the colors is psychological, not physiological.

As for why eyes didn't evolve a way to do Fourier analysis on light, I think the reason is that it's much more beneficial to be able to perceive what direction the light is coming from, to form an image of the objects around you, than to perceive the detailed spectra of the light they give off. It's impratical to do the same thing with sound (maybe because the wavlength of sound is so much longer, so an "acoustic lens" would have to be very large?), so the ear evolved the Fourier-analyzing cochlea to discern different sounds from each other by frequency instead of direction. —Keenan Pepper 19:54, 11 February 2006 (UTC)[reply]

Sounds good (after I Fourier analysed it :) ). I now wonder if there were physical limitations to doing both the direction perception and a Fourier analysis. Since most work is done in the eye, having the first leaves little physical room for the second. Of course this sort of thing could be done in the brain proper, but that has only 'recently' evolved to its modern human size, so there may simply not have been enough time for it to evolve. Then again, that typically human bit is the neocortex, which is designed for learning and not for hardwired apriori knowledge. DirkvdM 11:22, 12 February 2006 (UTC)[reply]

zebra stripes - dazzle display?

I was specutively considering what the colour of herding dinosoars might have been, and I got to thinking of zebra stripes. I wondered about the function of the stripes. Does it disguise the number in a herd from a distance in a heat haze? Or perhaps by a similar process allow young zebra to be better hidden in a herd? Alternatively, could it operate as a dazzle display against preditors at short distances i.e. the fast moving horizontal movement of their vertical lines interfering with a preditors judgment of distance or position as the preditor is about to pounce?

Dudley Warrinton--62.6.174.104

Read up on the sections that talk about zebras on Camouflage. enochlau (talk) 13:02, 10 February 2006 (UTC)[reply]

Another possible evolutionary explanation for zebra stripes is the handicap principle (this example is in fact mentioned by Amotz Zahavi in his book). The regular stripes highlight ("suitly emphazi", one might say) irregularities in their bodies such as atrophied muscles, making it easier for other zebras to choose the right partner and for predators to select the weakest prey. See handicap theory. David Sneek 20:50, 10 February 2006 (UTC)[reply]

Regarding eye-strain while using a computer

Is there any eyeglass available specifically used when seeing a computer? (Is there any special glass which can be used while using a computer?)

What is the name of that glass?

Can we use sunglass while using a computer? Or would a Anti-reflective coating glass be of any use?

From my own experience dealing with weak eyes applied to computers, I've learned that 90% of it is due to drying from not blinking enough, and the remaining 10% is from an uncomfortable focal length sought by your eyes (when focusing on the screen). It has nothing to do with 'glare' because i see the same impact from using a harsh polished CRT monitor in a high light situation as i do when using a very glare-proof LCD monitor in more mellow conditions. The tricks that work for me are: moving the monitor closer or farther (usually farther) to create a more comforable distance, and taking frequent breaks where my eyes are doing some other task (like looking out a window at long range) to allow them to normalize. If this doesn't help you, consult an Optometrist as there are glasses (very similar to reading glasses) that can help some people to better focus on computer screens. Hope this helps! --Jmeden2000 19:55, 10 February 2006 (UTC)[reply]

Tell your supplier of eye glasses what is the normal distance you sit from the computer screen. You can get prescription optimized for that distance.
Place your overhead lighting so as to minimize glare and interference.
- For example, the manual on setup for IBM monitors has an illustration of placement of monitor relative to overhead lighting of different kinds. If you are in an office with fluorescent lights (those long tubes with white bluish light in ceiling), you want them back to frunt releative to how you sit, not sideways, and you want them just to each side of you at your monitor, not directly overhead, to get maximum benefit of illumination and minimum interference at the subconsious eye level.
Clean the monitor regularly (no dust there).
Familiarize yourself with ergonomics to avoid any other kind of strain, some of which are far worse than eye strain.
- There is an issue related to color contrast of what is around your monitor. My monitor is black print on white background, except when there is color involved. Around my monitor is generally white paper with black print and a light yellow wall background. You want contrast that is easy on the eyes.
If you get fatigued, take a rest.
When buying replacement monitor, very carefuly self-educate yourselv about resolution, and seek one in which there is as little flicker as practical. The bigger the better, and go beyond SVGA.
There's other stuff that can be done, but it is generally too expensive for the average consumer.

User:AlMac|^(talk) 21:00, 10 February 2006 (UTC)[reply]

Trying changing your computers colour scheme. You can change Windows' settings by right-clicking on the desktop, selecting Properties, and clicking the Appearance tab. There's a range of options under Scheme - I use Eggplant. Also you can change the background colour of documents: the setting for that is on the next drop-down list, Item. 81.131.80.196 00:53, 11 February 2006 (UTC)[reply]

How to measure gelatin bloom

moved from Talk:Gelatin - I am carrying research on gelatine. I need some technical help on determining the bloom of gelatine. Can any of viever can suggest me how to determine the bloom of gelatine gel by using very simple instrument or design of instrument to measure bloom. sushil dhital - nepal pls mail to [email removed]

Titanium Dioxide 99.99998 purity

I am trying to find out what the different types of Titanium Dioxide can be applied to and the only one that i don't seem to be able to find much about is this one "Titanium Dioxide 99.99998 purity - powder format" Can anyone help me???

Kind regards.

Tania <Email removed>

This looks like it came from an ebay entry...

Hmm...Titanium dioxide is used in some paints, and I think possibly even toothpaste, and foundation. It has a white colour to it. --HappyCamper 20:15, 10 February 2006 (UTC)[reply]

You'd have to know which form the powder is in, rutile or anatase. Rutile has a higher refractive index and specific gravity, which affects transparency and particle size. Take a look at this image, you can see a slight difference between the two. GeeJo _{(t) (c)} • 17:20, 11 February 2006 (UTC)[reply]

daydreaming

how do we daydream even when we are wide awake?I thought dreams are only active when our body is at rest

It's sometimes thought that a hallucinogen (dimethyltryptamine) produced by the brain causes dreaming. There isn't really a clear explanation for why they occur, though. ‣ᓛᖁ

ᑐ 16:06, 10 February 2006 (UTC)[reply]

I dreamed yesterday some dogs hiding my research/sudy pappers in three holes. And in my dream was about ${\mathcal {\,}}N=4{\pi }v^{2}N_{o}({\frac {m}{2{\pi }kT}})^{(3/2)}exp{\frac {-mv^{2}}{2kT}}\,$ --HydrogenSu 18:36, 10 February 2006 (UTC)[reply]

I've changed it above.--HydrogenSu 12:19, 11 February 2006 (UTC)[reply]

That Maxwell-Boltzmann distribution must be weighing very heavily on your mind at the moment...are your pursuing something in physical chemistry? I think daydreams aren't quite so well defined for science to answer probably. --HappyCamper 20:08, 10 February 2006 (UTC)[reply]

By any chance, are you a physical chemistry professor? You sound like a physical chemistry professor, am I reading too much into this?--152.163.100.74 20:35, 10 February 2006 (UTC)[reply]

Daydreams can often be a mild self-induced hypnotic state in which the brain produces alpha waves. I was at the dentist yesterday. While I was having a tooth drilled, I was actively focussing my vision on the mobile gently circling overhead, and actively listening to the music being played (Villa-Lobos's Preludes for guitar) and actively tapping my fingers on my belly in time with the rhythm of the music. I was not entirely unaware of the dentist and her doings, but a lot less aware of her than I might have been. The same kind of thing happens, often fleetingly, when you're just sitting at your desk, say, but your mind is concentrated on something else that's not physically present. The thing at hand goes on a little holiday while you go on your inner journey, and we call that daydreaming. JackofOz 22:41, 10 February 2006 (UTC)[reply]

This reminds me, I've been having dreams with integrals lately. ? ?i?ff?? 01:45, 11 February 2006 (UTC)[reply]

you'll be OK as long as you can still differentiate your dreams from reality ;) Grutness...wha? 04:54, 11 February 2006 (UTC)[reply]

Dreams are real, don't let anybody ever tell you different. JackofOz 06:05, 11 February 2006 (UTC)[reply]

Integrals? Differentiate? Oh, never mind. It was pretty weak. Grutness...wha? 10:53, 17 February 2006 (UTC)[reply]

Thank you all for the reply above. I'm a universty student,year 3 but not a professor.(What "research/study" I called refered to do them in the future. :) ) That formula was originated from my learning in chapters about Blackbody of Modern Physics,not from Physical Chemistry. I'll keep trying still in M.P. . Keeping at it for myself!--HydrogenSu 12:19, 11 February 2006 (UTC)--HydrogenSu 12:25, 11 February 2006 (UTC)[reply]

How does a seed crack?

Hi, I am doing some research, and I have been searching on web for info about how a seed germinates after it is planted. I am not talking about specific environmental conditions that may be provided to help it germinate, but the specific mechanisms that are inherent in the seed to help it germinate. For example how does a seed know which way is up and which way is down for the roots and shoots to grow when it is buried within soil. Thank you for your time Rizvi

I vaguely remember something in school...something about a little pouch inside plant cells which has a higher density and tends to sink to the bottom of the cell so that it can tell which way "up" is. But I think you should wait a bit longer for a biologist to show up :-) Yeah, what is that called? --HappyCamper 20:05, 10 February 2006 (UTC)[reply]

It's all because of gravitropism, where since hormones (auxin) acculmulate, certain bits of the plant grows while others don't. They also can detect soil temperature, which prevents them from germinating too early or too late. smurrayinchester^{(User), (Talk)} 20:35, 10 February 2006 (UTC)[reply]

Removed the Secondary Logon service (Win2003 Enterprise)

In my efforts to play around with Windows 2003 and scaling it down, I used nLite to remove a bunch of things, including the Secondary Logon service. I thought to myself Ahhh I'll never need that service. And I didn't, for a very long time. Then I tried to install PostgreSQL (which I prefer running on Linux anyways, but oh well), which is the only app I've found I've used that actually needs to this stupid service. Is there any way to get it back without rebuilding my install image and reinstalling Windows? --131.202.90.23 20:23, 10 February 2006 (UTC)[reply]

Probably not. There might be some way, but I don't know of it. If I were you, I'd reinstall. -- Daverocks (talk) 05:36, 12 February 2006 (UTC)[reply]

'Magic'

How does this work? : http://www.mysticalball.com/. --Cosmic girl 21:55, 10 February 2006 (UTC)[reply]

When you choose a two-digit number and delete the sum of its digits from it, you always end up with a number that is divisible by 9, that is: 9, 18, 27, 36, 45, 54, 63, 72, or 81. If you check these numbers on the table, you'll see they all have the same flower petal-like symbol next to them, so that's the symbol you'll get every time. :) --Ashenai 21:58, 10 February 2006 (UTC)[reply]

Yup. Also, they change the symbol that you get, but each of the multiples of 9 will have the same symbol on any given time. (i.e.- the symbol that is the correct answer will change over time, but examination of the table will always show that 9, 18, 27, 36, etc. all have that same symbol) EWS23 | (Leave me a message!) 23:28, 10 February 2006 (UTC)[reply]

And the only two multiples of 9 that have different symbols than the rest are 99 and 90, which aren't reachable (there is no 2-digit number less than 100 whose sum subtracted will give you 99 or 90).--24.231.16.6 03:26, 11 February 2006 (UTC)[reply]

Awesome, thank u guys...hey EWS23, do u want me to leave u a message? or is that just part of your nickname....hhaha, cause I've seen that 'leave me a message' thing following a lot of nicknames.--Cosmic girl 03:41, 11 February 2006 (UTC)[reply]

It's just a separate link to his talk page, to make it easier for people to leave messages there. Same as the "Wha?" on my sig. Grutness...wha? 05:00, 11 February 2006 (UTC)[reply]

Absolutely right, just an easy link for people to contact me. I do love to receive messages though...that orange box telling me I have a new message just brings a smile to my face. :o) EWS23 | (Leave me a message!) 05:06, 11 February 2006 (UTC)[reply]

Cooking with wine

When you cook with wine, would be be reasonable to say that the alcohol is not boiled off because it forms an azeotrope with water? --HappyCamper 22:35, 10 February 2006 (UTC)[reply]

Tragically not. The ethanol-water azeotrope contains about 95% ethanol by weight. When you start at a lower concentration of ethanol, the boiling point of the system gets higher, and you lose ethanol faster than water. In other words, except for very short cooking times, the alcohol from the wine is almost all lost during cooking.

This phenomenon is what makes distilled beverages possible. Distillation relies on the tendency for ethanol to end up in the vapour fraction, from which it can be condensed and collected. (The azeotrope puts an upper limit on the purity of ethanol that can be recovered by normal distillation; to go above 95% purity requires other techniques.) TenOfAllTrades(talk) 22:55, 10 February 2006 (UTC)[reply]

"Eat with your children, that way you'll always have a little whine with your dinner." StuRat 01:54, 11 February 2006 (UTC)[reply]

Hmm...what a pity. Then it must be my imagination that the alcohol is still around. An expensive bottle of Chardonnay as a soup base put to waste in the name of experimentation...Thanks for the answers though! --HappyCamper 05:50, 11 February 2006 (UTC)[reply]

Another thing to note is that in many jurisdictions, distillation is illegal, but increasing alcohol concentration by freezing is not. moink 02:30, 12 February 2006 (UTC)[reply]

When I was a kid, we sold fresh squeezed apple cider to pay for camp. We noticed that sales really picked up after it turned into hard cider. True story. StuRat 04:47, 12 February 2006 (UTC)[reply]

help with my biology project

hi, my names tara and in a second year pharm science student.

im doing a solo paper and experement on casien in curd, starting withun pasterised bovine milk , so far iv found how to clean, skim and seperate crds and whey and iknow that there is a high conc of casien in the whey but im stuck on what test to prove that thats whats in my sample. iv exhausted all the books in the collage liabary, and have just spent over six hours this week on the net trying to find it, but my results from both dont give me a clear answer

do you know if any of there are right maillard reaction casien hydrolisis test kappacasien and Ca phosphate stabilisation

if im any way right please tel me, i need to prove that there is casien in the curd i produce myself in the lab.

yours hopefull tara

Email removed. enochlau (talk) 03:17, 11 February 2006 (UTC)[reply]

Tara, As a pharm science student you have to be careful about spellings...in this case, it's casein, not casien, so you're having trouble finding references. This .pdf file markets a lutex-agglutination based antibody test for casein. Probably not practical for your purposes, though, unless all you have to do is describe the test. - Nunh-huh 07:54, 11 February 2006 (UTC)[reply]

Articles about clinical immortality due to future medical advances?

I'm fond of the future, how we'll live, and how long we'll live. Therefore, what articles are relevant to the prolonging of lifespans due to future medical advances? Also, immortality due to future medical advances? --Shultz 23:08, 10 February 2006 (UTC)[reply]

Life extension and Engineered negligible senescence describe some of the research. ‣ᓛᖁ

ᑐ 23:24, 10 February 2006 (UTC)[reply]

sex, is any of this true?

Sex is a beauty treatment. Scientific tests find that when women make love they produce amounts of the hormone estrogen, which makes hair shine and skin smooth.
Gentle, relaxed lovemaking reduces your chances of suffering dermatitis, skin rashes and blemishes. The sweat produced cleanses the pores and makes your skin glow.
Lovemaking can burn up those calories you piled on during that romantic dinner.
True, evidently, but it must be vigorous sex. ? ?i?ff?? 00:00, 11 February 2006 (UTC)[reply]
As opposed to what? DirkvdM 14:49, 11 February 2006 (UTC)[reply]
Sex is one of the safest sports you can take up. It stretches and tones up just about every muscle in the body. It's more enjoyable than swimming 20 laps, and you don't need special sneakers!
Well, sneakers might be included, if the participants are so inclined... ? ?i?ff?? 00:00, 11 February 2006 (UTC)[reply]

I would object to the word safest. Nothing says I love you like an incurable STD.--24.231.16.6 03:29, 11 February 2006 (UTC)[reply]

I also object to the word sport. At the very least we lack an article on competitive sex. However, I thoroughly support it's creation; it'd be much more fun to watch at the Olympics than dressage. GeeJo _{(t) (c)} • 14:35, 11 February 2006 (UTC). GeeJo _{(t) (c)} • 14:35, 11 February 2006 (UTC)[reply]
Don't forget about the sperm competition. DirkvdM 14:49, 11 February 2006 (UTC)[reply]
Sex is an instant cure for mild depression. It releases endorphins into the bloodstream, producing a sense of euphoria and leaving you with a feeling of well-being.
instant cure, no - but it can alleviate some of the symptoms. And can prove very distracting from nagging worries, which are often a cause of mild depression. Grutness...wha? 05:04, 11 February 2006 (UTC)[reply]
The more sex you have, the more you will be offered. The sexually active body gives off greater quantities of chemicals called pheromones. These subtle sex perfumes drive the opposite sex crazy!
To the extent that this is true (which is debatable since it's very subjective), it is equally true of people who are attracted to the same sex as it is of people attracted to the opposite sex. JackofOz 01:30, 11 February 2006 (UTC)[reply]
Sex is the safest tranquilizer in the world. IT IS 10 TIMES MORE EFFECTIVE THAN VALIUM.
I think this is meaningless. How would you measure effectiveness and dose? —Keenan Pepper 01:33, 11 February 2006 (UTC)[reply]
It is a good tranquilliser for males. Doesn't always work that way for females though. Grutness...wha? 05:04, 11 February 2006 (UTC)[reply]
maybe not always, but when it does . . . one needs a fairly powerful tranquilliser to induce unconsciousness and temporary paralysis. this will seem an idle boast, but i have witnessed female orgasms cause both -- and no, there was no rohypnol (or any other drug) involved. 67.68.205.214 08:23, 11 February 2006 (UTC)[reply]
Kissing each day will keep the dentist away. Kissing encourages saliva to wash food from the teeth and lowers the level of the acid that causes decay, preventing plaque build-up.
I have my doubts about this one. ? ?i?ff?? 00:00, 11 February 2006 (UTC)[reply]
Sex actually relieves headaches. A lovemaking session can release the tension that restricts blood vessels in the brain.
Same here. Lots of people complain about having sex while on a headache just makes it worse. ? ?i?ff?? 00:00, 11 February 2006 (UTC)[reply]
Technically might be possible for some types of headache, though. I recall reading a column where a woman tried taking a small amount of Viagra, and at first the increased bloodflow went to her head, causing a massive headache, but when she was sexually stimulated the blood went to her genitals and thus away from her head, the headache eased (I would assume the principle extends to many blood pressure-related headaches, not just those caused by inappropriate medication). Confusing Manifestation 12:53, 11 February 2006 (UTC)[reply]
A lot of lovemaking can unblock a stuffy nose. Sex is a natural antihistamine. It can help combat asthma and hay fever.
A little birdie told me that the unblocking effect occurs for them, but it's very short lived. No idea of what the physiological mechanism causing it is. --Robert Merkel 03:47, 11 February 2006 (UTC)[reply]

-- User:Nicholie

I think you might be interested in this. I've been receiving quite a lot of chain emails from my "friends" lately, and most of them end with something like "if you break the chain, you will not have a good relationship in the future" or something even more ridiculous. I always either break the chain and ignore the email, or reply to the chain email's sender angrily. I recommend you to do the same--break the chain and convince the sender of the email to stop spreading lies. Anyways, here are my comments on some of your statements:

Estrogen is constantly being produced by a female human's ovaries. During puberty and in girls, it stimulates the development of gametes and secondary sex characteristics. After puberty, it lubricates the vagina and maintains the condition, as well as the elasticity, of the vaginal lining. It cannot make hair shine or make skin smooth, because those things are not controlled by estrogen--they're controlled by how well you take care of your skin/hair.
Dermatitis, skin rashes, and blemishes are skin conditions that are not affected by sexual intercourse. The claim that sweat cleanses the pores is ludicrous. Pores are openings in the sebaceous glands (which are in the skin), and I don't know how they can be cleaned. Sweat obviously doesn't make your skin glow because sweat doesn't glow. (By the way, have you ever seen glowing skin/sweat?)
Any kind of exercise can burn calories, even breathing or moving your eyes to read a computer screen. However, sexual intercourse is a very inefficient way to burn calories. You'd be much better off walking 500 m, or clapping your hands rigorously during a performance.
If you can make sex competitive, then yes, it's a sport. It's also pretty safe--at least, safer than smashing your head to pieces by banging it against a helmet. There are a lot of muscles in the body, and very, very few of them are stretched when having sex. As to whether sex is more enjoyable than swimming 20 laps, it depends on your personal opinion.
If you like sex, of course it can instantly relieve mild depression! Orgasms are pleasurable, and yes, they do release endorphins. Endorphins are pain-relievers and it is true that they leave a sense of well-being (according to this webpage). Personally, I doubt that this sense of well-being can be stronger than the desire to have sex. I frequently have mild depressions, and masturbating doesn't seem to help. --Bowlhover 18:03, 11 February 2006 (UTC)[reply]

February 11

comparison of energy content in food

what are the comparisons of energy contents in food such as millet,cassava and rice.----------

You can check the energy content of various foods at: USDA National Nutrient Database. --Uthbrian (talk) 00:18, 11 February 2006 (UTC)[reply]

Note that the "energy content" is the number of calories. StuRat 01:47, 11 February 2006 (UTC)[reply]

And you should check out our page on calorie for a discussion of how it applies to food specifically (in comparison to physics, chemistry, etc.). --Fastfission 22:16, 11 February 2006 (UTC)[reply]

You could of course name it by its proper name Joule, but somehow the SI system hasn't gotten through to dietists (this is not a US thing - same here in Europe). DirkvdM 11:25, 12 February 2006 (UTC)[reply]

Laptop for computer illiterate person

Hi. I don't really know anything about computers, but I would like to purchase an inexpensive laptop for my work. I'd like it to be able to do 'power point presentations', use the internet, email, and word processor. What kind of laptop should I be looking at?

Those are trivial work, so you don't seem to need anything very expensive or powerful. Go for something cheap but durable, I say. ? ?i?ff?? 01:43, 11 February 2006 (UTC)[reply]

From the items you mentioned, it sounds like a rather minimal laptop should do the job. So, try getting the cheapest one you can find. StuRat 01:45, 11 February 2006 (UTC)[reply]

However, I would advise you to buy it from a store that specialises in selling computers rather than, for instance, a supermarket - they should also be able to advise you better. Computers, despite the popular perception, are not toys and you should do some shopping around to find out what you can get for your money. But, in principle, I agree with Kieff and StuRat - a very basic model will do all the things you list without any problems. — QuantumEleven | (talk) 13:35, 11 February 2006 (UTC)[reply]

It may be worth emphasising that no one laptop should be harder or easier to use than any other. Cheaper isn't simpler, nor is more expensive. You should consider either getting classes or buying some suitable books, otherwise the machine is likely to be just baffling. One more tip: "backups" are important. Keep this point in mind until you understand why, and are doing them. Notinasnaid 16:06, 11 February 2006 (UTC)[reply]

gemology

Where's the question? What about gemology? :| ? ?i?ff?? 01:41, 11 February 2006 (UTC)[reply]

You clearly can't read txt. The question says: "Gee - I'm all og. Why?" The answer is either that you're an ancient Amorite king or a type of cake or bread. Grutness...wha? 05:08, 11 February 2006 (UTC)[reply]

I kind of hope it's the latter. For some reason I'm more comfortable hearing from a cake or loaf of bread who has gained sentience and typing abilities than I would be hearing from a man who has been dead 3000+ years. EWS23 | (Leave me a message!) 05:16, 11 February 2006 (UTC)[reply]

No, no, nothing to do with Og. Gemology is an anagram of either Leggy Moo (in which case the question is about average leg length in bovine quadrupeds) or Go Leo Gym (in which case the questioner is called Jim, is born under the sign Leo and wants some exercise routines appropriate to that Zodiac sign. So, combining the two possibilities, it would seem that our questioner is an exercise-crazy vet. Now what's the question? - Adrian Pingstone 09:26, 11 February 2006 (UTC)[reply]

Sound Response

Hi, im working on a project about sound response but can't find any wikipedia infomation on it. The technology im using is based on an audio float controller, assigned to models in 3D studio max; the models move and react to the input from wav. files, eg rotate whenever there is a beat in a song. Does anyone have any other suggestions as to what to search for or where to look to find more on animation reacting/moving to sound? thanks for your time.

Fusion

Give me a list of elements which can undergo nuclear fission.210.211.231.51 03:39, 11 February 2006 (UTC)[reply]

By the sounds of Nuclear fusion, all of them. But only under the right conditions. Are we talking about a Supernova or a Lab beaker? --24.231.16.6 03:45, 11 February 2006 (UTC)[reply]

Are you interested in nuclear fusion or nuclear fission? For fission, in nuclear power reactors and nuclear weapons, it's almost always the spontaneously fissionable isotope of uranium, uranium-235, and the artificially created element plutonium which undergo fission (though the final stage of a multi-stage nuclear weapon uses the neutrons created by the fusion secondary to cause U-238 to fission). Other potential candidates are uranium-233, which can be bred from thorium, and neptunium-237, which is found in nuclear waste.

For nuclear fusion, see nuclear fusion and fusion power.--Robert Merkel 03:59, 11 February 2006 (UTC)[reply]

All elements can undergo nuclear fission, but fission of elements lighter than iron requires energy, while fission of iron or elements heavier than iron releases energy. The opposite is true for nuclear fusion: fusion of elements lighter than iron releases energy, while fusion of iron or elements heavier than iron requires energy. (Note that here, "requires" and "releases" are relative terms--I'm talking about whether the output of energy is less than the input or not.) 72.136.70.187 04:39, 11 February 2006 (UTC)[reply]

Oops. The above comment was by me--Mozilla Firefox logged me out for some reason. Bowlhover 04:44, 11 February 2006 (UTC)[reply]

Note that some isotopes are unstable (radioactive), so undergo spontaneous fission at a steady rate described by their half life, while others are stable, and must be struck with high energy particles to undergo fission. Generally speaking, the heavier the element, the larger percentage of it's isotopes will be radioactive. StuRat 04:59, 11 February 2006 (UTC)[reply]

"All elements can undergo nuclear fission,"

I must have been daydreaming when I wrote this. Since hydrogen-1 has only one proton, it obviously can't undergo fission. Helium-3 has only one neutron, and since all atoms have to have at least one neutron, it can't be split into two atoms. (If anybody here finds a incorrect/misleading statement that I, or anybody else, made, please don't just ignore it. Talk about it.) Bowlhover 05:15, 11 February 2006 (UTC)[reply]

I disagree. Hydrogen-1 does not have any neutrons. There is a radioactive isotope of hydrogen, called tritium, and there are several radioactive isotopes of helium. An atom that undergoes fission does not necessarily produce other atoms, but can also produce other decay particles. See this clickable periodic table for a list of all known isotopes, and whether they are stable or not [11]. See isotope table (complete) for another presentation of all known isotopes. StuRat 05:22, 11 February 2006 (UTC)[reply]

I agree with you. All elements can undergo fission, but not all isotopes can. Bowlhover 05:43, 11 February 2006 (UTC)[reply]

Also note that elements up to lead generally have a mix of radioactive and stable isotopes (with exceptions for technetium and promethium, which only have radioactive isotopes). All isotopes of all elements heavier than lead are radioactive, however. This might explain why lead is used for radioactive shielding, it's the heaviest element that has an isotope which isn't itself radioactive. StuRat 05:55, 11 February 2006 (UTC)[reply]

Sorry for the question about fission. I meant- 'give me list of elements which can undergo fusion.' -- (same guy who asked the question)

That question was answered as well: All of them. Though only the elements up to Iron will release energy from doing so. GeeJo _{(t) (c)} • 14:11, 11 February 2006 (UTC)[reply]

Well, the very heaviest element may not be able to successfully undergo fusion. Now, where exactly you draw the line and say "this is the heaviest element" is then the question. (If an atom only holds together for a trillionth of a second, does it really count as an atom ?) StuRat 18:29, 11 February 2006 (UTC)[reply]

According to current physics, it'd be Untrioctium, since any larger atom requires electrons to travel at superluminal speeds. GeeJo _{(t) (c)} • 19:38, 11 February 2006 (UTC)[reply]

I think that atoms are atoms, no matter how short their half-lives are. It's unfair to refuse credentials just because an atom has a half-life that's not in the human timescale. --Bowlhover 22:42, 11 February 2006 (UTC)[reply]

As a matter of pedantry, any element greater than 138 doesnt really form atoms - no electrons can orbit the created nuclei. Rather it's just an atomic nucleus, in the same manner as an alpha particle, which aren't typically referred to as "atoms" GeeJo _{(t) (c)} • 23:13, 11 February 2006 (UTC)[reply]

And of course ultimately this process would produce neutronium GeeJo _{(t) (c)} • 16:59, 12 February 2006 (UTC)[reply]

Yahoo Accounts

Does anyone have any idea how many Yahoo accounts have been created? Captain Jackson 04:42, 11 February 2006 (UTC)[reply]

Millions. Next question? --Cyde Weys 05:06, 11 February 2006 (UTC)[reply]

Hydrogen

Why isn't hydrogen considered a metalloid even though it can form H+ and H- ions? EamonnPKeane 12:18, 11 February 2006 (UTC)[reply]

Because that's not the defining characteristic for a metalloid. See the article for more details. However, it is possible to get metallic hydrogen under some rather extreme conditions. GeeJo _{(t) (c)} • 14:02, 11 February 2006 (UTC)[reply]

Also, if the definition you gave was correct, you'd also have to count oxygen as a metalloid, since it can form both cations (oxonium) and anions (oxide). GeeJo _{(t) (c)} • 01:35, 12 February 2006 (UTC)[reply]

1.'Cause ${\mathcal {\,}}H_{2}\,$ is a molecule. If H in extra-out space,then it(H) can be reagarded as metal. But must in extreamly high density I guess.
2.H and other Hs are bounded by Hydrogen bounds.
3.Yes,"Hydrogen"Su is in.--HydrogenSu 21:08, 18 February 2006 (UTC)--HydrogenSu 09:52, 14 February 2006 (UTC)[reply]

Different mobile browsing technologies

Apart from WAP and html, is there any other type of mobile browsing?

Is java (mobile) another way of browsing, or is it just related to html?

Is there any other type of mobile browsing?

In addition to WAP there is Wired Equivalent Privacy. JWSchmidt 17:19, 11 February 2006 (UTC)[reply]

No. WEP is not related to WAP in any meaningful way. The combination of HTTP/HTML and WAP are both ways of marking up and delivering a document. Java is a programming language, often used to deliver dynamic content online (i.e., to deliver something like a program, not something like a document). In addition, the software that interprets both HTML and WAP content, that runs on a cell phone or other mobile device, is often written in Java (but that program is not delivered online; it is preloaded at the factory). 66.30.201.209 18:36, 11 February 2006 (UTC)[reply]

I think JWSchmidt was thinking of WPA, or Wi-fi Protected Access. WPA and WEP are wireless network security methods, and are not related to WAP in the context of mobile phones. WAP is the dominant technology at the moment to deliver content to mobile phones. Although it would be possible to deliver pages formatted with HTML through a different means, most phones only support WAP. Regarding Java, you might be able to get a Java app that uses WAP to help you browse. -- Daverocks (talk) 05:46, 12 February 2006 (UTC)[reply]

Big big digital universe

Hello, thanks for having this service!!

I would like to know how many websites there are on the internet. I know the number must be astoundingly large by now, maybe more than 5 billion??

Thanks for your efforts in advance!! Happy Pre-Valentines Day!

InquiringMind

Here are some links that can give you an idea. David Sneek 13:23, 11 February 2006 (UTC)[reply]

focal point of parabole

how does one calculate (in simple tems) the focal point of a parabole according (I imagine) to the angle of curvature? How can I find the answer on wikipedia if someone is kind enough to help?----

Parabola. TenOfAllTrades(talk) 16:11, 11 February 2006 (UTC)[reply]

Samurias and Vikings

there is a points to all this, just keep reading, and hopefully you can help me answer my question, i didnt know were to put it, so i tried the Science Section.

In the ancient world there were many classes and countrys and warriors, but the Vikings are by far the most repeated, accounts of them coming on to shores in there Viking long boats or throwing there huge axes at men charging them, terrorizing villages and countrys alike let alone there berserkers were mean enough, crazy enough and bad enough to take on dozens of men at a time.They were one of the most feard people in Europe and lived in the harshes enviroments ie: what is now Russia, and Greenland.

The Samurais were also one of the most feared warriors in Japan, they were quick, diciplined, and would take there own life if told to do so. They were bodyguards, warriors, even assassins. There light armor made them quick, and the curved swords were fast and cut ferociously. You showed them respect, nd if you dishonored them it could meen you lose your head without a hesitation.

My question to whom ever can answer is this, "In the MedievalAges, who would win in a battle against each other, the Fierce Vikings, or the Diciplined Samurais? Who had the better Weapons and Armor, Who could do more damage, and what effect do you think Samurai swords and armor would have against Viking swords, axes and armor and shields." I thank you for any information you can give me.

For reference, please see the case of WP:Pirates VS Ninjas, hope that helps answer your question--205.188.116.74 16:25, 11 February 2006 (UTC)[reply]

that just states that this question in nonsense......

Where are they fighting? Did the Vikings come to Japan, did the samurai come to Scandinavia, or are they meeting somewhere in between? Which army is 5000 miles as the crow flies from home, in strange terrain, with no supply lines, surrounded by a population with which they cannot communicate and which is very probably hostile? What kind of battle are they fighting? Are the Vikings conducting a hit-and-loot-and-burn-and-run raid against the samurai, or are the samurai forcing the Vikings into a pitched battle? Are they fighting on land or at sea? Which army is better-led? (probably the samurai, but. . .) Who is mounted? Which era are these samurai from? (their organization, tactics, and weaponry changed over the years.) Battles are not won by skill or technology alone.

I once read of a question guaranteed to keep philosophy students (or any other imaginative and argumentative group of people) busy for hours: "Who would win in a fight between a shark and a lion on the moon?" This reminds me of it. —Charles P._(Mirv) 19:32, 11 February 2006 (UTC)[reply]

I was ready to file this one in the "too stupid to answer category" but you have given us an excellent, edifying, amusing answer. I will have to remember it. Nice. alteripse 23:48, 11 February 2006 (UTC)[reply]

Katana#Comparisons with European swords has an interesting/theoretical comparison. - Cybergoth 14:49, 12 February 2006 (UTC)[reply]

grape seed oil

I understand the health benefits of grape seed oil. Please inform the manufacturing procedure, machinery suppliers to make Grape Seed Oil. (e-mail address removed)

Grape seed oil has a little bit as does vegetable oil in the extraction section, but overall we don't have much on that. As for suppliers, that's not really something Wikipedia is all about, but google would probably be helpful, or find a vegetable oil trade group and they could lead you to suppliers. - Taxman ^Talk 17:53, 11 February 2006 (UTC)[reply]

Plane Waves

Why can plane waves not be normalized?
I had a bit read some few parts of Fermi's notes. He said monochromator waves belong to plane waves? I might such make the description.....I may make something wrong in my memories. Please discuss it. Or share thoughts to each other.

(Why cannot plane waves be normalized?)-by the way needing a "short" answer only-this way saying,Brintish-English? I say thanks first to any reply for the aboves.--HydrogenSu 18:17, 11 February 2006 (UTC)[reply]

I've spent a little time searching at [12] and [13]

But don't understand very well still.

--HydrogenSu 18:34, 11 February 2006 (UTC)[reply]

Note to readers, don't waste your time following the footnote links above, as I did, since they are just the monochromator and plane waves links repeated from above, in a weird form. StuRat 19:14, 11 February 2006 (UTC)[reply]

Indeed,my view of life is a half both for trust and ??(sorry,I forget its English). :)--HydrogenSu 19:22, 11 February 2006 (UTC)doubth?[reply]

doubt? smurrayinchester^{(User), (Talk)} 22:35, 11 February 2006 (UTC)[reply]

In order to normalise a wave you have to multiply it by some number so that the integral of the square of the wavefunction (the probabilty) = 1 (i.e the probabilty of finding the wave quantum somewhere in space = 1)

A plane wave exists everywhere in space. The integral will therefore be infinite. There is no number that you can multiply infinity by to get 1. Theresa Knott | Taste the Korn 00:36, 18 February 2006 (UTC)[reply]

Verify Maxwell's speed distribution

Q:Verify Maxwell's speed distribution function:: ${\mathcal {\,}}N(E)={\frac {2{\pi }N_{o}}{({\pi }kT)^{3/2}}}E^{1/2}e^{E/kT}\,$

Sol:

"

{\mathcal {\,}}N=4{\pi }v^{2}N_{o}({\frac {m}{2{\pi }kT}})^{(3/2)}exp{\frac {-mv^{2}}{2kT}}\,

.

(?Pour quoi c'est le commencé pour la question?) --HydrogenSu 19:26, 12 February 2006 (UTC)[reply]

Convert Cable TV input to RCA or S-Video?

I have a TV that one of my kids broke the connector for the cable TV input (F connector). And getting it fixed costs more than is worth. This TV has both RCA input and an S-Video input.

Does anyone know if I can find / use and adaptor to either of these two input connectors in place of the F-Connector?

Thanks,

Bruce Bbottger 18:52, 11 February 2006 (UTC)[reply]

The F-type connector carries a radio-frequency (antenna) signal on which the video signal is encoded. (Or it may contain multiple, separately-enccoded channels, e.g. if it's cable TV.) The RCA and S-video connectors, on the other hand, are for single, line-level, composite video signals. So they're very different. The only "adapter" from the F-type connector to one of those other two would have to be a TV tuner, and while those exist, it would certainly cost more than fixing the broken F connector (or, if what you say is true, than the set is worth).

Fixing the broken F-type connector (or kludging in another one, connected to the same wire inside) shouldn't be that expensive. Maybe you just need to get a second estimate. Steve Summit (talk) 19:55, 11 February 2006 (UTC)[reply]

I'm not sure if your probem is the same as mine, but I managed to shear off the antenna connector on my tv. I am using an old video player (or you could use a Set-top box) an an adaptor. I run the antenna into the VCR, then run RCA from the VCR to the TV.--Commander Keane 02:28, 12 February 2006 (UTC)[reply]

That's an excellent workaround (using the VCR's tuner) and it should work for Bruce. What comes from an antenna is essentially the same as what comes from cable. - mako 23:33, 12 February 2006 (UTC)[reply]

Mississippi/Missouri Rivers

Your page on the Missourri River lists its length as 2315 miles, and that of the Mississippi at 2350 miles. Since the Missouri is really just a tributary of the Mississippi, that would make the true length of the total Mississippi 4665 miles, the longest river in the world, but you have their total length listed as just 3,900 miles, third in the world. Why is this?

Anthony

Thanks!

Look at a map. The Mississippi starts north of Minneapolis, Minnesota. The Missouri joins it at St Louis. The Mississippi's distance between Minneapolis and St. Louis probably accounts for most of the that discrepancy, if the 3900 mile distance is from the source of the Missouri to the Gulf. alteripse 23:45, 11 February 2006 (UTC)[reply]

Or, to put it anothr way, the Missouri doesn't join the Mississippi right at the end of the larger river. It joins it about 1585 miles in from the gulf coast. 1585 + 2315 = 3900. Grutness...wha? 23:52, 11 February 2006 (UTC)[reply]

I've made a very simple diagram: http://72.136.70.187/mississippi.png to illustrate the answer to your question. --Bowlhover 01:22, 12 February 2006 (UTC)[reply]

How are we actually defining "length" here? Would this not be the same situation for coastlines - with the length increasing as the measuring stick that you are using gets smaller? Richard B 13:07, 17 February 2006 (UTC)[reply]

EM Spectrum

Is electric power frequency (50Hz or 60Hz ) included in the electromagnetic spectrum or not . please be precise.

thanx

Imran

Yes, it is. Electromagnetic radiation that has a frequency of 50 Hz or 60 Hz are ELF radio waves. (ELF stands for "extremely low frequency", and it covers frequencies from 3 Hz to 300 Hz). --Bowlhover 22:13, 11 February 2006 (UTC)[reply]

Giving Blood

Would you lose weight after giving blood, or would it just stay the same because the blood gets replaced?

According to the article on blood donation: "Plasma volumes will return to normal in around 24 hours, while red blood cells are replaced by bone marrow into the circulatory system within about 3-5 weeks, and lost iron replaced over 6-8 weeks." So if you donate blood, the liquid part of it gets replaced in about a day, while the red blood cells take much longer (3 to 5 weeks). Bowlhover 22:08, 11 February 2006 (UTC)[reply]

If you weighed yourself immediately before and after donation, you would notice a small drop on weight, similar to emptying your bladder. As Bowlhover mentions, the weight would be quickly replaced as you drank water to replace the lost blood volume. I don't imagine there would be any effect lasting beyond a day, although I cannot be certain. It certainly wouldn't be an efficient or healthful way to lose weight, of course. — Knowledge Seeker দ 22:21, 11 February 2006 (UTC)[reply]

What about blood pressure?

I was thinking of asking this anyway, and this seems like a good place. Is giving blood a good way to reduce blood pressure? It seems logical, but it's not listed at Blood donation#Benefits. —Keenan Pepper 22:46, 11 February 2006 (UTC)[reply]

The volume of a unit of blood is about 500 cc, about half a kg of immediate weight loss. BUT, about 70% of that weight is water and you replace it as soon as you drink. The remaining 125 g of solid matter removed in the blood is replaced when you eat a hamburger. So yes, you lose wt, but not much. The blood pressure would drop as the 500 cc is removed, but that much can be quickly compensated for, so any blood pressure lowering effect is most likely a matter of minutes rather than hours or days. alteripse 23:43, 11 February 2006 (UTC)[reply]

So the blood vessels just squeeze a little harder and the pressure goes back to normal? —Keenan Pepper 23:52, 11 February 2006 (UTC)[reply]

That's right. A little renin, a little aldo, and presto, pressure. alteripse 00:03, 12 February 2006 (UTC)[reply]

I did a specific study on this. The average adult has 10 pints of blood. In an average donation, an adult gives 1 pint. That is 10%. On average, blood pressure goes up more than 10cc directly after giving blood. Over the next 2-3 days, blood pressure remains higher than normal, but drops a little each day. After a week, all those in the study had normal blood pressure again.

Now, why? Blood pressure will rise quickly after giving blood because the arteries and veins constrict to help get blood to the brain. Then, the body will add water to the blood to fill the volume back to normal levels. Water is not the same density as blood, so blood pressure remains high until the blood is back to normal. In healthy people, blood density and blood pressure were normal by the third morning. In older and sick people, it took much longer to get density and pressure back to normal.

Also of note is cholesterol. As expected, cholesterol levels drop dramatically when giving blood. However, they return to normal in a few days. Abrubt changes in cholesterol are believed by some to lead to fatty liver disease, so this study is in a new department to check on liver effects in those with high cholesterol who give blood regularly. --Kainaw ^(talk) 01:31, 12 February 2006 (UTC)[reply]

While the 10% of blood given during a donation can be easily compensated for by the body, higher percentages can't, so will result in lower BP. I've often thought that in people with severe high BP, removal of blood should be considered as a treatment option. I would do it in a continuous loop, as in hemodialysis, where the amount outside the body can be controlled precisely to adjust BP. I would think such a method could be used to quite precisely control BP, especially in patients who are already undergoing hemodialysis. StuRat 04:04, 12 February 2006 (UTC)[reply]

Blood pressure goes up after giving blood, as the body compensates for the missing blood volume. Giving blood is *not* a good way to reduce blood pressure. Raul654 04:15, 12 February 2006 (UTC)[reply]

You seem to have missed what I said, so I will repeat it. While BP goes up after giving up to 10% of blood volume, there is a point where the body can no longer compensate. So, giving significantly more than 10% should cause the BP to decrease. StuRat 04:28, 12 February 2006 (UTC)[reply]

Yes, going into shock can also reduce blood pressure. Neither is a particularly good idea ;) Raul654 04:34, 12 February 2006 (UTC)[reply]

Also, most of our blood is good for us. Sure, you will lose some bad cholesterols and the like when giving a lot of blood. However, you also lose chemical signals for the body, white blood cells to fight infections, and red blood cells to keep organs functioning optimally. It was not part of my study, but I found that many people got sinus infections the day after giving blood. My assumption is that reduced flow to the head with reduced white blood cells is a formula for a bad sinus infection. --Kainaw ^(talk) 15:08, 12 February 2006 (UTC)[reply]

I would think the most obvious reason for an infection would be that bacteria were introduced thru the hole in the skin and vein. StuRat 05:32, 13 February 2006 (UTC)[reply]

Wow. "Blood is good for you" — what a revelation! =) —Keenan Pepper 16:38, 12 February 2006 (UTC)[reply]

Heat production and life processes

Do all life processes produce heat? I've wondered about the circle of snow and ice free area around trees and plants. Do they actually produce enough heat to keep the area free of snow, or is there some other explanation? -- Fyslee 23:01, 11 February 2006 (UTC)[reply]

The second law of thermodynamics states that whenever energy is converted from one form to another, some must be wasted as heat, so the answer to your first question is yes. —Keenan Pepper 23:15, 11 February 2006 (UTC)[reply]

Although I would suspect other causes keep the area free of snow -- but I'm at a loss as to what. Anyone want to answer the second part of the question? -Quasipalm 23:47, 11 February 2006 (UTC)[reply]

Those "other causes" include shade. Even the branches of a tree empty of leaves will reduce the amount of snow hitting the ground underneath it. Because less lands there, it is more likely to melt away more quickly. Some of it will probably be due to a slight heating effect, though. Grutness...wha? 23:58, 11 February 2006 (UTC)[reply]

Stated differently, are there any endothermic reactions used by life forms ? StuRat 01:37, 12 February 2006 (UTC)[reply]

Well, without answering the question specifically, a number of endergonic reactions are used by life forms, most notably photosynthesis. Oddly, our page on endothermic reactions doesnt make explicit the difference between the two. GeeJo _{(t) (c)} • 03:13, 12 February 2006 (UTC)[reply]

February 12

Cellular automata

Why do some animals (like sea animals,I don't know exactly wich) exhibit cellular automata patterns on their 'skin', shell or outter covering? does this have an explanation? or is it not yet known why this happens?. oh and also,can a cellular automata hold an 'infinite' ammount of info. and/or processes? If not, is there any 'machine' hypothetical or real, (like a quantum computer) than CAN hold an infinite ammount of information and/or processes?. I mean, not being infinite in itself, it has to be finite, to be a machine, but infinite 'inside it' like, 'subjectively infinite'. can that be? or am I on drugs...--Cosmic girl 02:12, 12 February 2006 (UTC)[reply]

I'm not sure about the first part, but it seems like intercellular communication might be able to do things reminiscent of automata.
Someone's managed to design a memory cell for a universal Turing machine in Conway's game of life. It would be terribly impractical as a computer, though. Omega point may be what you're looking for. ‣ᓛᖁᑐ 02:48, 12 February 2006 (UTC)[reply]

thank you :), yeah I knew about the omega point, it's a cool theory.--Cosmic girl 03:13, 12 February 2006 (UTC)[reply]

For your first question see Cellular automata#Cellular automata in nature. For your second question you have to distinguish between the mathematical model of and a real (physical model) cellular automata. In the real world the maximimum amount of information that can be stored is limited by the Bekenstein bound and other physical laws so we will (according to our current knowledge) not be able to build machines that can hold an infinite amount of information of perform an infinite amount of computation in a finite amount of time. Mathematically speaking, there are cellular automata which are equivalent to Turing machines which are able to hold an infinte amount of information. —Ruud 03:00, 12 February 2006 (UTC)[reply]

ok, thanx for the 1st link...well when I ask about a computer that can contain an infinite ammount of info. I don't mean a computer that is inside our universe, but one that IS our universe, I suppose that the bekenstein bound wouldn't apply to the universe as a whole...do you think this is possible at all? since I know nothing about math nor computer science.--Cosmic girl 03:17, 12 February 2006 (UTC)[reply]

I think the Berkenstein bound does apply to the universe as a whole. At least, I can't think of any reason why it doesn't. Nothing that is finite, including the universe, can store an infinite amount of information. And by the way, you're on drugs. :) --Bowlhover 03:26, 12 February 2006 (UTC)[reply]

haha! I knowwww, I'm on neurochemicals...at least they are natural drugs! :|--Cosmic girl 03:31, 12 February 2006 (UTC)[reply]

Here's a paper that derives the total information content and processing power of the universe: http://arxiv.org/pdf/astro-ph/0404510 —Keenan Pepper 03:30, 12 February 2006 (UTC)[reply]

thank you! :) --Cosmic girl 03:48, 12 February 2006 (UTC)[reply]

Well, there's nothing magical about cellular automata. They're just a machine where you have lots of similar cells, all of them can only be in few different states, and the state of each is influenced only by the state of its close neighbours. Even a very simple cellular automaton (where there are only a couple of states and the transition rules are very simple) can have interesting properties. So, no wonder such a case can realize in these animals. – b_jonas 18:33, 12 February 2006 (UTC)[reply]

thanks :) --Cosmic girl 22:33, 13 February 2006 (UTC)[reply]

medical question?

What do you think would happen if a vandal with OCD discovered wikipedia?-152.163.100.74 05:27, 12 February 2006 (UTC)[reply]

Then we have a obsessive vandal! :) --hello, i'm a member | talk to me! 05:41, 12 February 2006 (UTC)[reply]

if? - Nunh-huh 05:51, 12 February 2006 (UTC)[reply]

Well, they'd be unstoppable. I have very mild Pure Obsessional OCD, but I have no intention of vandalising Wikipedia, luckily for you guys. And even if I did obsess over vandalism, I wouldn't actually do any. I'd just go crazy in my head. :P -- Daverocks (talk) 05:55, 12 February 2006 (UTC)[reply]

There are probably a lot of users with undiagnosed OCD, as there would be in any collection of humans as large as this. Once they discover Wikipedia, it might seem like a natural home for them. (I wonder if that means .... nah.) JackofOz 07:05, 12 February 2006 (UTC)[reply]

I think they'd be too busy checking to be sure they turned off the stove to do much editing of wikipedia. Or maybe you mean Obsessive-Compulsive Personality Disorder (known in some places as Anankastic Personality Disorder)?

They'd probably get blocked, which would hopefully put them off or turn them into good contributors. smurrayinchester^{(User), (Talk)} 16:13, 12 February 2006 (UTC)[reply]

Mass edit in sibelius

How does one mass edit (in tradition of Finale) in Sibelius? --hello, i'm a member | talk to me! 05:41, 12 February 2006 (UTC)[reply]

Oh, and how do I add a forte (piano), among other things?

Why does the score always stop at the end of the page? I've checked their help system.

Note: the question is about Sibelius notation program, not the composer Jean Sibelius. That had me scratching my head for a bit. :) DirkvdM 11:41, 12 February 2006 (UTC)[reply]

By "mass edit", do you mean "copy and paste"? I remember Finale had a strange interface for that. Don't think of it in terms of Finale, just think of normal editing commands. Copy and paste are on the edit menu and have the shortcuts cmd-C and cmd-V. (If you're on Windows, "cmd" means "control", I think.) There's also a slightly quicker way: you can duplicate the currently selected measures by holding option/alt and clicking where you want them to go.
For forte and piano: hit cmd-E to add an expressive mark. Holding down the command key as you type letters like "f" and "p" creates dynamics. So forte is cmd-E cmd-F.
You're probably asking how to add more blank measures to the end of the score; hit cmd-B. Online help for Sibelius isn't that great; the printed manual, on the other hand, is an excellent reference.
Hope this helps. rspeer / ???ds? 07:11, 12 February 2006 (UTC)[reply]

From my experiences on Wikipedia, I have found that a small group of people believe that Johann Sebastian Bach used Sibelius and Finale. However, as you can tell from my edit here, I'm not a member of that small group. :o) EWS23 | (Leave me a message!) 07:51, 12 February 2006 (UTC)[reply]

I don't think Sibelius himself used Sibelius, even. :) --BluePlatypus 10:02, 12 February 2006 (UTC)[reply]

Well that's patently untrue. Neither Finale nor Sibelius had been invented when J. S. Bach was composing. He composed using a program which he wrote himself in INTERCAL and which ran on an abacus. P. D. Q. Bach, however, has done most of his work with Finale. And gin. --George 17:34, 12 February 2006 (UTC)[reply]

Hmmm. He must have been writing for the "well-tampered" clavier. JackofOz 02:04, 13 February 2006 (UTC)[reply]

Is Chris Angel the magician on A and E Bogus?

I think he must pay the so called crowds and random people he performs for and selects for assistance. His tricks are totally fake. Does anyone have any evidence that they are real?

Magic isn't real, it's illusions and deception. You could say his magic is "fake" because he does not actually have supernatural powers. But if he can successfully deceive his audience, it's "real" in a sense because he is accomplishing his intended purpose. rspeer / ???ds? 07:19, 12 February 2006 (UTC)[reply]

It would only be deception if the performer claimed to have supernatural powers, such as actually creating the rabbit that comes from the hat, or creating the doves that appear from inside his coat. I've never heard of a magician making such absurd claims (and if they did, nobody would believe them anyway because they would know it was not meant to be taken literally). What they do is certainly illusion - although it's not necessarily any less "real" because of that (depending on your definition of reality). We don't watch a movie or a stage play and then criticise it for being illusory, deceptive or not real. "Magic" in the modern meaning of that word is simply another form of entertainment.JackofOz 07:39, 12 February 2006 (UTC)[reply]
And "so-called crowds" is also a misnomer. In 99.9% of the cases, people magicians on the street perform to are indeed random passers-by. - Mgm|^(talk) 12:45, 12 February 2006 (UTC)[reply]

genetics

can biotechnology/genetic technology trace out a person's origin?if so,how?

It can trace the female line of ancestry waaay back, through mitochondrial DNA. Tracing the male line isn't possible by that method, though it is possible to work one generation back and find out whether a particular person is another person's father by other biotechnological means. Grutness...wha? 08:30, 12 February 2006 (UTC)[reply]

If I'm not mistaken, patriarchal lineage can be traced by analysis of the y chromosome.--Mark Bornfeld DDS 13:51, 12 February 2006 (UTC)[reply]

Semen storage in liquid nitrogen

I was reading the article on semen and I as curious: how long can semen be stored in liquid nitrogen/cold storage? People could be stored for a long time via cryonics. Could sperm be stored forever? What about body parts and organs? Are there any side effects on the sperm cells after defrosting? --Blue387 08:16, 12 February 2006 (UTC)[reply]

Storing individual cells like spermatozoa is easier than storing tissue or an entire body, because there's less damage caused by the freezing\unfreezing process (which is mostly caused by crystallization). Since when freezing semen you have lots of sperm cells, and they're just relevant individually (unlike a tissue), the overall damage and loss is not really a problem. This is not the case for tissues, organs or anything more complex, but that might change with advances on medicine. Now, I'm not entirely sure about how long these can be stored, but I'd guess a whole lot of time if the right conditions are maintained. There are very few process that could damage the samples significantly once they're properly freezed and stored. ? ?i?ff?? 08:51, 12 February 2006 (UTC)[reply]

Pretty much indefinitely. Most sperm dies in the freezing process, but once it's frozen, the ones that have survived will do so pretty much indefinitely. It doesn't work as well for bodily organs though. --BluePlatypus 15:20, 12 February 2006 (UTC)[reply]

the mouse and the empire state building

A discussion from the pub, in theory, if a mouse fell from the top of the empire state building would it survive?

Cats that fall off a building have the best chances of surviving if they fall from a height over something like 5 floors (can't remember precisely). Below that they may not have enough time to prepare for the fall (turn around and arch their bodies into a 'spring'). Above that it doesn't matter because the friction counterbalances the acceleration through gravity. The reason this works for cats and not for humans is that they are much smaller and thus have a higher surface-to-weight ratio. For mice this is even more true. I don't know if mice are as able as cats to take the blow, but they would not need as much of it, so I'd say they stand a good chance. Actually, I once had the chance to check this. I had caught a mouse in a box (chased it to a corner where the only opportunity to hide was in a box on its side and then put the box upright - simple) and then brought it to the balcony, where it jumped right out of the box and over the fence, resulting in a four floor drop.

Alas I didn't see the mouse after that, so I'm not sure, but I suppose I didn't see it because it quickly ran away and thus survived. For how long is yet another matter, because the inside of the box was full of blood-stripes (poor mouse, and I tried so hard to do the right thing...). DirkvdM 11:55, 12 February 2006 (UTC)[reply]

Actually, I think the thing about falling cats was that the greatest fatalities and injuries occurred around the 7th or 8th floor, with a falling-off in either direction, and there were a few factors involved, some of which would apply to the mouse case. IIRC, some of those factors were the size (bone strength increases with size squared and mass with size cubed so a smaller animal has relatively stronger bones), the time needed for the falling cat to twist itself around to land on its feet rather than something more fragile/essential for survival, the drag caused by fur, and a few other things. Confusing Manifestation 14:05, 12 February 2006 (UTC)[reply]

Makes me sad to think how this data was experimentally retrieved. ? ?i?ff?? 14:32, 12 February 2006 (UTC)[reply]

If it makes you feel better, it was based on cats brought to veterinary emergency rooms in New York City following accidental falls—nobody was dropping cats on purpose. On the downside, this means it wasn't a controlled experiment and further research may be needed. The original reference is Whitney O., Mehlhaff C. (1987) "High-rise syndrome in cats." J Am Vet Med Assoc. 191(11):1399-403. (Link goes to PubMed abstract.) TenOfAllTrades(talk) 18:22, 12 February 2006 (UTC)[reply]

I imagine that the mouse would probably be too small to be caught up in the net, and would just fall through the spaces hitting the pavement directly, so basically.. no--152.163.100.74 14:49, 12 February 2006 (UTC)[reply]

Hum, yes, but if there is mud instead of pavement, would the mouse go splat on the ground?

As a couple people have implied, this is really an argument about whether a mouse can survive a fall at its terminal velocity. You'd have to do a calculation to find out how quickly the mouse would reach terminal velocity, but I imagine it can't be more than 10 stories. So, the mouse would have an equal chance (perhaps a better chance) of surviving the 102 stories of the Empire State building as it would from your 10 story apartment building. My guess: it really depends how it lands. If it landed on its head or back, it probably doesn't survive. On its limbs, probably survives, but with injuries. And of course, there's also the case of the acrobatic mouse who could probably land perfectly with only the effects of disorientation. EWS23 | (Leave me a message!) 17:51, 12 February 2006 (UTC)[reply]

I'd agree with EWS23's assessment; I suspect that lucky mice would survive, unlucky ones wouldn't—but I've never measured the terminal velocity of a mouse, so I can't be certain. I do know that it's virtually impossible to kill a squirrel through falling. Their tails are large and fluffy enough that their terminal velocity is...non-terminal. Mice don't enjoy this benefit; a hairless tail doesn't create a lot of drag. TenOfAllTrades(talk) 18:09, 12 February 2006 (UTC)[reply]

In 1928, J.B.S. Haldane wrote an essay called On Being the Right Size. He starts by referring to human characters up to 60 feet tall in the novel Pilgrim's Progress, and then says:

Gravity, a mere nuisance to Christian, was a terror to Pope, Pagan, and Despair. To the mouse and any smaller animal it presents practically no dangers. You can drop a mouse down a thousand-yard mine shaft; and, on arriving at the bottom, it gets a slight shock and walks away. A rat would probably be killed, though it can fall safety from the eleventh floor of a building; a man is killed, a horse splashes. For the resistance presented to movement in the air is proportional to the surface of a moving object. Divide an animal's length, breadth, and height each by ten; its weight is reduced to a thousandth, but its surface only by a hundredth. So the resistance to falling in the case of the small animal is relatively ten times greater than the driving force.

Given the long history of mining in England, I'm thinking that his examples of mineshaft falls were not made up... and that the answer to the original question would be yes, because the mouse would indeed reach terminal velocity.

As a side point, I note that the Empire State Building has a profile that gets narrower toward the top, so a mouse that "fell from the top" would not really reach the ground at all. To do so, it would have to be launched horizontally with considerable speed. However, I take the question to refer to a straight fall from the same height, or, say, from the World Trade Center if that was still around. --Anonymous, 18:50 UTC, February 12, 2006.

That wasn't really a terrorist attack. They saw this discussion coming and feared experimentation. It was really a 'mice first' action group. DirkvdM 09:59, 13 February 2006 (UTC)[reply]

Can we use sun-glasses while reading?

Can we use sun-glasses while reading? Do all sunglasses protect us from ultra violet rays only?

Why couldn't one use sunglasse while reading? Whether it's bad for the eyes, I don't know, is that what you mean to ask?

Since UV light is invisible any dark sunglasses would also filter other (visible) frequencies. Actually, cheap sunglasses probably don't give any UV protection at all. I now wonder if there are any pure UV sunglasses. They would be clear, wouldn't they? DirkvdM 11:59, 12 February 2006 (UTC)[reply]

Yes, you can read with sunglasses, but if you have trouble reading with your glasses on, they may have glass optimized for seeing longer distances. Talk to an optometrist, opthamologist or eye doctor if you feel reading requires different glasses, or try reading without them (if reading without them works, you can use glasses without extra correction in them and just UV protection).

Can a student memerize formulas by Sound?

According to my experience,I feel it's much better when studying. For some parts of physics,even. Anyone else can talk about your studying/or learning about science? Try sharing.--HydrogenSu 12:12, 12 February 2006 (UTC)[reply]

It is possible to memerize anything by sound. Some people find it easier than other methods, but it varies from person to person. --ßjweþþ (talk) 14:07, 12 February 2006 (UTC)[reply]

Some people remember sounds much better than others. I come from a family of many actors. A genetic gift (and curse) is the ability to replay things I've heard as though I have an internal tape recorder. I'm not that great at it as I need someone to give me a little dialog to start it going. But, some in my extended family are very good at reciting things they've only heard once - like the special of the day at a restaurant we went to last week. I think it is a common tool among actors as they have to read and recite lines continually and cannot take time to concentrate on doing so. --Kainaw ^(talk) 21:11, 12 February 2006 (UTC)[reply]

When I was taking acting classes, it was always recommended that we study our lines aloud instead of trying to memorize them just by reading silently. The speaking of the lines helps you to remember them. User:Zoe|^(talk) 22:18, 14 February 2006 (UTC)[reply]

I think human's feelings on "hearing" sound are better than sights. Maybe hearing will appear with "annocing/lound/sound" at the same time when we were children's learning,But human cannot "light" on something,never. I guess human's brain accept sound more easily than sights,in signal processing or memorizing something.--HydrogenSu 21:17, 18 February 2006 (UTC)[reply]

The Sun and The Earth

How does the sun heat the earth. Is it the ultra violet rays the produce the heat?

Well heat is produced in the sun by nuclear fusion. This heat travels to Earth by infrared radiation (it couldn't travel by conduction or convection because space is a vacuum).--ßjweþþ (talk) 13:20, 12 February 2006 (UTC)[reply]

Hello. What happens is that the light comming from the Sun gets "caputred" by the Earth's athmosphere. Thanks to a greenhouse effect due to the clouds, the heat generate by the presence of all these particules stays inside the athmosphere. =)

Xionbox 13:28, 12 February 2006 (UTC)[reply]

PS: let's make this clear and a bit more rigourous: space is not a vactum: it's almost totally empty because of what is called in french accrétion gravitationnelle (sorry, I'm used to studying scien in french =/). What that does is that every little piece of matter tries to compact it-self with other matter to create. That's how gravity starts (thanks to matter).

So space is not a vaccum, it's just empty. Therefore, is you put any matter near nothing, well the matter will go towards the empty area. In other terms, because there is no pressure in space, an area near a depressurized one will depressurize because the matter will go towards the empty area as explained earlier.

Also, heat is not produced by the Sun: photon are produced by the Sun and when there photons are in contact with something, then, thanks to all the particules moving around, what we call heat is generated. ;)

Earth does receive some infrared from the Sun, but it receives far more visible light, which causes most of the heating (insolation). This amounts to about 1366 watts per square meter (the solar constant), which is mostly retained due to the greenhouse effect. The Sun produces quite a lot of heat, but as said above, there isn't enough matter in space to conduct the heat directly. ‣ᓛᖁ

ᑐ 15:41, 12 February 2006 (UTC)[reply]

Somebody seems to be very confused. For a start, vacuum means empty. See vacuum. --Shantavira 18:14, 12 February 2006 (UTC)[reply]

In fact Shantavira, vacuum did not have the same signification for me as I am French and in french, the direct translation of that word seemed to me as the wrong word to describe correctly what happens. Sorry. Xionbox 22:16, 12 February 2006 (UTC)[reply]

Thanks for clarifying; I was quite confused by the statements about space not being a (near-)vacuum as well. What did you think it meant? — Knowledge Seeker দ 22:30, 12 February 2006 (UTC)[reply]

I would like to add that the space between clumps of matter in space is not quite a vacuum. In space there is plenty of hydrogen aimlessly floating around. Well not plenty, but something like 2 atoms/m^2? I don't really remember. Also, Xionbox's accrétion gravitationnelle, translates to gravitational accretion, or gravitational attraction (for those of us who couldn't figure it out). Accretion disc's are formed near black holes. -- User:Mac_Davis Now, February 2006 (UTC)

According to Vacuum#Vacuum in space, there are a few hydrogen atoms per cubic centimetre in outer space. This is proportional to a 2000 km x 2000 km x 2000 km cube with a few 1-mm-in-diameter spheres scattered around inside it. For this reason, we can safely call space a vacuum, just as we talk about one object touching another object when in reality, atoms cannot touch each other unless under extraordinary situations. --Bowlhover 01:44, 14 February 2006 (UTC)[reply]

Why are the cloudy nights warmer than the clear nights?

Because the clouds prevent heat from escaping, so it is warmer.--ßjweþþ (talk) 13:26, 12 February 2006 (UTC)[reply]

Clouds transmit short wavelength radiation, but reflect long wavelengths. Radiation from the sun is short wavelength, and radiation escaping earth is long wavelength, because it has less energy. So it gets trapped (greenhouse effect). deeptrivia (talk) 13:39, 12 February 2006 (UTC)[reply]

Well, during the day the clouds mostly transmit the sun's shortwave radiation (that is, allow it to pass through to the Earth), but some of it is reflected back into space due to the clouds' albedo. During the night, the clouds absorb and then re-emit the longwave radiation of the Earth as a function of the clouds' temperature (see Stefan-Boltzmann law). So, some of that emission is into space, and some of the emission is back to the Earth. That added input of radiation from the clouds make the surface warmer on a cloudy night than it would be on a clear night. EWS23 | (Leave me a message!) 18:08, 12 February 2006 (UTC)[reply]

P.S.- The result of the Stefan-Boltzmann link above is that lower clouds warm up the surface more than high clouds (because the low clouds are warmer). So, if you prefer a warmer night, you'd rather have a deck of low stratus clouds than a high, wispy cirrus cloud. EWS23 | (Leave me a message!) 18:20, 12 February 2006 (UTC)[reply]

Also, remeber that days with clouds are going to be warmer than days with no clouds because warm air sucks up more moisture than cold air. It's kind of a chicken and the egg thing: most often the heat is causing the clouds, not the clouds causing the heat. -Quasipalm 18:28, 12 February 2006 (UTC)[reply]

Warm air does not "suck up" more moisture than cold air. In fact, air cannot suck up water at all. When the air is warm, liquid water evaporates more quickly; when it's cold, the water vapour that's already in the air condenses more easily. --Bowlhover 19:56, 12 February 2006 (UTC)[reply]

I think what Quasipalm meant is that warm air can hold more water vapor than cold air. Of course, with the same amount of water vapor, this means you will have more clouds (condensed, liquid water) in cold air than you would in warm air. EWS23 | (Leave me a message!) 20:42, 12 February 2006 (UTC)[reply]

That's exactly what I meant, in simple terms. See this link for more info. I like this summing up, "at temperatures near freezing, you can expect big honking snow flakes and lots of them. One those comparatively rare occasions when it snows near 0 F, you can expect individual snow crystals, but not very many of them because such cold air can't "hold" as much water vapor. Below about -40º, you can expect only very small crystals to fall, and very few of them at that. "

The idea of "holding" a substance only applies if that substance is being dissolved, and water vapour does not dissolve in air. With the same concentration of water vapour, more clouds are formed if the air is cold, not because cold air cannot hold as much vapour as warmer air (which is false), but because water vapour condenses more readily if the temperature is low. --Bowlhover 23:44, 12 February 2006 (UTC)[reply]

I could start a debate with you, but I have a feeling we'd just be debating semantics. Condensation occurs when the air is saturated and there are condensation nuclei present. Whether the air is saturated is determined by temperature (i.e.- the saturation vapor pressure/mixing ratio is a function of temperature). At lower temperatures, condensation doesn't occur because condensation is any easier/harder at that temperature, but rather because at that temperature the saturation vapor pressure is lower than it is at higher temperatures. A good answer I found about this is located here. Be sure to read the whole thing- while the first sentence supports your point, the first sentence of the fourth paragraph indicates that it's pretty much the same thing. EWS23 | (Leave me a message!) 03:30, 13 February 2006 (UTC)[reply]

Well, it's much harder to make a blanket statement about how clouds effect temperatures during the day. Without any other variables, simply putting clouds into an environment will cool that environment because the clouds reflect sunlight back into space before reaching the ground. However, where I live in Seattle, Washington, cloudy days are often warmer than clear days because we are in a warm, marine air mass from the Pacific Ocean rather than a cold, arctic air mass from Canada. The arguments you make have a lot of other variables that it would probably be counter-productive to address here, but have to do with more clouds due to heat (convection) or more clouds due to cold temperatures (a common cause of fog). EWS23 | (Leave me a message!) 18:58, 12 February 2006 (UTC)[reply]

GPL software and icons under the GPL

I'm developing some software which will be open source and licensed under the GPL. I have found Noia icons on the web which are also licensed under the GPL. I'd like to use one of the icons (unchanged and intact) in the package as the main icon for the Windows application.

Am I allowed to do this?
Am I required to give credit or distribute anything? (I will of course give credit, but am I required to do so?)

Regards, --Spaceman85 13:25, 12 February 2006 (UTC)[reply]

AFAIK you are completely able to do this, there is nothing to stop you. As for credit, I'm pretty sure the GPL requires you to give it. --ßjweþþ (talk) 14:02, 12 February 2006 (UTC)[reply]

Cheers for that, that's what I thought. If anyone else has any thoughts on this then please add them. Thanks again! --Spaceman85 15:08, 12 February 2006 (UTC)[reply]

Bjwebb has the right idea. You're allowed to use them as long as you credit the original author of the work. — Ilyan e p (Talk) 15:24, 12 February 2006 (UTC)[reply]

clouds

Why does a cloud turn black or dark when its about to rain?210.211.231.137 14:47, 12 February 2006 (UTC)[reply]

Because rain clouds are thicker than non-rain-clouds, and not as much sunlight passes through them. --Bowlhover 16:04, 12 February 2006 (UTC)[reply]

See colours of clouds for more details. GeeJo _{(t) (c)} • 16:06, 12 February 2006 (UTC)[reply]

Light

Why can we see only light of wavelength 400-700nm not others like ultraviolet light or infrared?

The human retina contains three types of cone cells, which are adapted to detect light of either short, medium, or long wavelengths. Their sensitivity is typically limited to the 400 to 700 nm range, but some people can see ultraviolet wavelengths down to 380 nm, or infrared wavelengths up to 780 nm. The ability to see ultraviolet or infrared doesn't give humans an evolutionary advantage, which explains why their vision is limited to these particular wavelengths. ‣ᓛᖁ

ᑐ 16:17, 12 February 2006 (UTC)[reply]

I would think there would be an evolutionary advantage to infrared detection, if it allowed us to see hidng enemies, predators, and prey. StuRat 19:16, 12 February 2006 (UTC)[reply]

Yes that would be nifty, but we'd have to have a way of keeping our eyes at or below the ambient temperature. Otherwise the heat "noise" from the eye itself would drown out the "signal" body heat. Perhaps it is analogous to a contrast ratio less than 1? Tzarius 22:31, 12 February 2006 (UTC)[reply]

I don't know what the optics of infrared are like, but I believe that infrared due to heat from the brain would completely overwhelm the infrared emitted by animals at a distance. — Knowledge Seeker দ 22:53, 12 February 2006 (UTC)[reply]

I think that's the point Tzarius made. The eye would have to be cooled (and not just a bit). Is there a way (other than evaporating sweat) a body could use to cool an organ? Is anything like this done in any living thing? Of course the sensor wouldn't have to be part of the eye. Just a rough indication of 'there's something over there somewhere' would already be useful (the other senses can take over after that). And for that no lens is needed. Where to place it is a different matter. On the inside of the hand, so we can give it some direction? I now envision an animal (well, a human in this case) sneaking through the grass and raising its hand like a periscope, turning it left to right, scanning for the presence of lions. :) DirkvdM 10:13, 13 February 2006 (UTC)[reply]

How about eyes on stalks, like a snail ? StuRat 02:39, 15 February 2006 (UTC)[reply]

Colour

Do humans know the colour of ultraviolet light?

Yes and no. In fact, we know the colour of ultraviolet thanks to white light's spetre. We know that if it were possible for us to it, we would see it as a dark blue/violet. But we, as humans, do not see ultraviolet because our eyes is not adapted to see it.

PS: do humans... are you not human or did you not want an anwser regarding animals? Xionbox

Xionobox, do you think the above line was a joke. You think i am an alien or some thing. From now dont send what you think "jokes". P.S. I know that some animals like bees are sensitive to UV light.61.17.48.173 09:31, 14 February 2006 (UTC)[reply]

In other words, ultraviolet light does not have colour because humans' eyes assigns colour to different wavelengths, and humans cannot see ultraviolet light. --Bowlhover 16:16, 12 February 2006 (UTC)[reply]

I think this is a perfect example of the difference between knowledge by description and knowledge by acquaintance. We know the wavelength of ultraviolet light, and we can figure out which objects reflect UV and which absorb it, but we can never really "know the colour" because we can't physically perceive it. Deep, huh? —Keenan Pepper 16:32, 12 February 2006 (UTC)[reply]

I have to go with Keenan Pepper here. We know the wavelength of ultraviolet light, but it has no color (to humans, at least). Color exists only in our brains; it is a perception, not an external phenomenon, although it corresponds somewhat to the pattern of frequencies of light. A great variety of frequency-patterns are perceived by someone to be the same color, and two people may view the same light and see it as different colors. Since it cannot be sensed by humans eyes, the brain has no awareness of it, and it is colorless. — Knowledge Seeker দ 18:59, 12 February 2006 (UTC)[reply]

Can't people who have had their lens(es) removed (aphakia) see some ultraviolet? Ardric47 23:37, 12 February 2006 (UTC)[reply]

So I heard... The lens normally blocks UV, remove it and UV photons get to the retina. What colour is perceived is a good question: I'd guess it'd look blueish as the receptors up that end of the spectrum will have the best response. I'm sure I saw an anecdote about WWII, where elderly people were taken in boats a few miles off the US coast to look for spies signalling with UV lights. Malcolm Farmer 12:34, 19 February 2006 (UTC)[reply]

Another 'color' of ultraviolet is black, in that something that reflects only that range of wavelengths will appear black to us in the same way that something that reflects only green will appear green. Or 'clear', if it transmits light as well. Then it'd look like glass. Black Carrot 00:46, 13 February 2006 (UTC)[reply]

Which brings me back to the notion I put forward that pure UV sunglasses would be clear (transparant to the human eye). Which may very well have spawned this question in the firt place. DirkvdM 10:17, 13 February 2006 (UTC)[reply]

2006 DICE Summit

I don't know if this is appropriate to mention here. But the DICE (Design, Innovate, Communicate, Entertain) Summit is a large gathering for game designers to come together and some of the biggest names in video game design are there. It was Intended to happen from the 8th to the 11th. A man named Will Wright (creator of sims, and the upcoming PC game "Spore") was going to be a speaker there on the 10th. I was wondering if anyone knows, or could find out what he spoke about. If there is something that summarizes his speech out there you guys are the ones who could point me in the right direction. If this isn't appropriate for this, my mistake and feel free to remove it, and thanks in advance. Chris M. 16:39, 12 February 2006 (UTC)[reply]

Nuvola icons for Windows?

I recently installed a Windows theme (http://tev.o2php.com/custo/Nuvola.php) based on David Vignoni's Nuvola icon set (original icons, http://www.icon-king.com/v2/goodies.php). Now I'd like to customize some of my shortcut icons, but I'm not sure which Nuvola icons are in which files. Are the full set of icons -- including any that might not be used in the theme -- available in one DLL or ZIP file anywhere? Or, is there any free program that would convert them all without losing the transparency (as the ones I've tried so far do)? Seahen 16:51, 12 February 2006 (UTC)[reply]

Laptop Vs Desktop for reading purposes

I use the computer mostly for reading since I am a journalist. Would upgrading for a laptop or a tablet be of any use? Would a laptop be easy for reading purposes than a desktop? And would a tablet be more useful than a laptop?

Do you currently have any particular problems with reading on your current monitor? Notinasnaid 17:26, 12 February 2006 (UTC)[reply]

I would think a large plasma screen would be the easiest to read, being clear and bright. An LCD is quite clear, but can also be fairly dim. A CRT is bright, but can be blurry. StuRat 19:11, 12 February 2006 (UTC)[reply]

Being a journalist, do you need to carry it around with you 'on the job'? DirkvdM 10:20, 13 February 2006 (UTC)[reply]

The way I see it, there are only two good reasons for choosing a laptop over a desktop: size and portability. Do you need to carry the computer around with you? Is desk space (at home) at a premium? If you answer "yes" to any of these questions, then you should consider a laptop over a desktop. If the answer to both is "no", then a desktop is a better choice - you get a better and larger screen, better keyboard and mouse, better expandability, more equipment (hard drive, optical drive, graphics card...) options - plus, for the same amount of computer power, desktops are cheaper than laptops. So, unless you need to carry your computer around with you, or have a small desk, stick with your desktop.

As for reading, StuRat is right, it's the monitor that matters most, not the type of computer. Again, with a laptop you are stuck with whatever monitor it comes with, while with a desktop you can plug any monitor into it that you want. — QuantumEleven | (talk) 08:24, 14 February 2006 (UTC)[reply]

Clenching jaw

Whenever I clench my jaw fairly hard in the abscence of any other significant noise, I hear a short, very high-pitched sound in both ears, which fades after a second or two. Any idea why this might be? GeeJo _{(t) (c)} • 17:08, 12 February 2006 (UTC)[reply]

I don't know what's causing it, but the name for the symptom is tinnitus. —Keenan Pepper 18:27, 12 February 2006 (UTC)[reply]

Could this be related to TMJ disorder ? 19:06, 12 February 2006 (UTC)

I doubt it, there's no pain or swelling associated with it. I'm not really concerned about it, I was mostly curious as to whether other people commonly experience this. GeeJo _{(t) (c)} • 19:49, 12 February 2006 (UTC)[reply]

The noise may well be coming from the temporomandibular joint, but joint noise is not in itself a disorder. This is especially true in the case of the TMJ, which is sufficiently close to the ear that even minor noise could be audible. Noise could be the result of movement/compression of the fibrocartilage disc located between the articular surfaces of the mandible and the temporal bone, or perhaps flow of synovial fluid within the joint capsule. Alternatively, the noise may not be from the joint at all, but may represent equalization of pressure between the middle ear and pharynx through the eustachian tube.--Mark Bornfeld DDS 20:10, 12 February 2006 (UTC)[reply]

I get that too, but I have to clench my jaw uncomfortably hard. The sound is just like tinnitus, and similar in pitch to the 15 kHz from a television. It's a pure note, not like the crunching sound of joint noise or the whoosh of air in the Eustachian tube. --Heron 20:57, 12 February 2006 (UTC)[reply]

I too get this effect of a high pitch noise. On a separate issue, I find that if I am performing some "acutely hard task" - such as squeezing a pair of cutters to cut through a thick piece of wire, or untightening a very tight bolt - I instinctively end up clenching my teeth whilst performing the action! -- SGBailey 23:29, 18 February 2006 (UTC)[reply]

Programs' Usage of Hard Drive

Something is triggering the I/O Smart on my Diskeeper, but I can't tell which program is doing it. Is there a (preferably free) program that tracks how much each program is using a drive, like how Task Manager shows how much each program uses the CPU? --AySz88 ^-^ 18:04, 12 February 2006 (UTC)[reply]

Oh yeah, and this is a Windows box. --AySz88 ^-^ 18:07, 12 February 2006 (UTC)[reply]

I suggest you kill off the programs one at a time with Task Manager, if necessary, until the hard disk access stops. This should tell you which program was doing it. StuRat 18:59, 12 February 2006 (UTC)[reply]

I found the program doing it (oasclnt.exe from McAfee integrated into the AOL Security and Safety Center), but it feels unsafe to do that; I'd rather see programs' disk usage.... --AySz88 ^-^ 19:10, 12 February 2006 (UTC)[reply]

The unix program is lsof. Try Googling for a windows hack of lsof. --Kainaw ^(talk) 20:07, 12 February 2006 (UTC)[reply]

Thank you! From http://phpwiki.sourceforge.net/phpwiki/CygwinTips I eventually found http://www.sysinternals.com/Utilities/ProcessExplorer.html, a Task Manager clone-ish thing which has a sortable "I/O Delta" column, which is good enough. Thanks again! --AySz88 ^-^ 02:03, 13 February 2006 (UTC)[reply]

The exact same feature is available in the standard edition of windows task manager, but i won't discourage use of the sysinternals version as it is a very very handy tool. Another word of caution: depending on how much ram you have, much of the disk usage could be due to swap data coming off the hard drive. Be sure to analyze page faults as they would account for a lot of usage when your swap file is busy.

cleaning old paths for good

Any one knows how to delete the files in windows or registry of uninstalled software. i have tried registry cleaner, registry repair, HS winperfect, clean registry, ashampoo but non cleans all the files and thats what i need to install a fresh piece.

If you're having serious problems, I'd reinstall windows. I usually have to do this once every year or two. -Quasipalm 18:31, 12 February 2006 (UTC)[reply]

You have to? Why? Just curious...Ardric47 23:39, 12 February 2006 (UTC)[reply]

The windows registry becomes increasingly bloated by applications, and many of the keys and registry errors accumulate over time. These build up because many registry keys, fonts, and dll's, are not removed by uninstallation of the associated applications. Most utility programs intended to correct or optimize the registry are configured to be conservative in rectifying the situation, since aggressive registry error correction can itself cause problems with currently used applications. A complete hard disk format and re-installation of the operating system and applications is the only sure way to restore the registry to like-new condition, as well as eliminate unneeded windows system files. It's a bit of a chore, though, especially since you need to re-download all those MS-Windows updates...--Mark Bornfeld DDS 18:43, 13 February 2006 (UTC)[reply]

Ah, the cluttered registry. I used to mess with that quite a bit back when I was using Windows 95, but I just assumed that with today's faster computers, the performance drain was insignificant. Or maybe I'm not paying attention very closely to how fast my programs are actually running. Ardric47 23:35, 13 February 2006 (UTC)[reply]

Macs versus Windows computers?

Why is it that the vast majority of graphic design and multimedia professionals insist that Macs are just better than Windows computers? 70.111.8.113 18:22, 12 February 2006 (UTC)[reply]

What kind of answer are you looking for? There are plenty of ads at apple.com that answer this question. —Keenan Pepper 18:40, 12 February 2006 (UTC)[reply]

That is for lots of reasons. First of all, Mac is a UNIX and Unices are multi tasks which means that when a program crashed, the system does not crash with it. Also, you have to know that Windows is a pale copy of Unices but a bad copy because it doesn't work as well as them and there are much less programms for Windows than for other Unices. In fact, Windows has the most non-free programs, but that is it. Also, Unices rock because they are correctly programmed. =)

Xionbox , a proud GNU/Linux user

I am also a proud GNU/Linux user, but don't the NT-based Windows versions have protected memory and preemptive multitasking? Let's not spread FUD. —Keenan Pepper 18:54, 12 February 2006 (UTC)[reply]

If memory serves, the NT kernel from which XP derives was written by IBM back in the good old days when Microsoft and IBM were allies, and was inspired by the design of the OS/2 kernel. And yes, it includes pre-emptive multi-tasking, virtual memory error checking, and all that jazz. Raul654 20:18, 12 February 2006 (UTC)[reply]

They do, but the FUD answer fails to take into account the love affair designers had with the Mac long before OS/X, when the Mac most definately was not a UNIX system (nor did it multi-tax well) --212.135.194.83 15:01, 13 February 2006 (UTC)[reply]

Pagemaker and the Apple LaserWriter. From there it's been a matter of impetus. --BluePlatypus 19:02, 12 February 2006 (UTC)[reply]

What is "impetus"? Can you say of it? Arigado-gozaimaz.--HydrogenSu 20:12, 12 February 2006 (UTC)[reply]

I assumed he meant it with the same meaning as inertia. Steve Summit (talk) 20:14, 12 February 2006 (UTC)[reply]

To the original poster: did you mean the question seriously, or as flamebait? Are you wondering why those graphic design and multimedia professionals have the preference they do, or are you trying to cast doubt on that preference? (A "straight" answer to the question, though one that is likely to be pretty inflammatory itself, would be, "Perhaps those graphic design and multimedia professionals insist that Macs are better because they are.") Steve Summit (talk) 20:19, 12 February 2006 (UTC)[reply]

This was a serious question, as I aspire to become a graphic designer, and I've heard through word of mouth that Macs are the preferred computers for design and multimedia. I'm just curious as to whether or not there are any solid reasons behind this. Javguerre 02:33, 13 February 2006 (UTC)[reply]

Two suggestions from me: a) because the Mac has snazzier graphics than Windows, people assume that the Mac is better for design work b) because the Mac has snazzier graphics than Windows, people who put style before substance are more attracted to it. I personally don't think there's a real difference since most tools are available (and work in a similar fashion) on both Windows and Macs. enochlau (talk) 23:05, 12 February 2006 (UTC)[reply]

As a graphics designer and artist who has used a wide variety of both macs and PCs over the years...it's fefinitely not the "snazziness". The Mac is far, far easier to use for design work, you can multitask programs without fear of the whole lot crashing on you simultaneously, and the user-friendliness of the mac interface makes it far easier to sue graphics-oriented programs. If I were ranking them, I'd put Macs top, with PCs just a little below the Etch-a-sketch. Grutness...wha? 05:50, 13 February 2006 (UTC)[reply]

Macs are fully integrated systems, with a single machine in mind diring design. All parts (hard- and software) are designed to cooperate perfectly. Which is why they work so well 'out of the box'. The drawback is that you have to go with the solutions Aopple comes up with. If you want something different you're screwed. Also, Apples are specifically designed for graphics stuff.

And lastly, I know a photographer who was also in doubt which to buy. He talked to some people at the recieving end of the photographs, who told him an Apple was better for them because it's better at handling stuff coming from others. But the guy concluded that since he was a photographer and thus not at the receiving end a PC made more sense for him. Alas I can't emember now what the reasoning was, but apparently it matters where in the 'product chain' you are. For a graphic designer, I suppose this suggests a Mac would be better. But I hope someone else picks this up to give you a better explanation. DirkvdM 10:35, 13 February 2006 (UTC)[reply]

H5N1

your n5h1 still should add about 10 nore country to the map but i is agreat job keep it going thank you kindly

Does this comment belong here? —Keenan Pepper 18:56, 12 February 2006 (UTC)[reply]

No, not a question. ? ?i?ff?? 05:58, 13 February 2006 (UTC)[reply]

Why are we writing in small text? - Akamad 06:52, 13 February 2006 (UTC)[reply]

Keenan thought it was a good idea. -- User:Mac_Davis

If someone answers the question, they will be suitly emphazied. ‣ᓛᖁ

ᑐ 16:01, 13 February 2006 (UTC)[reply]

A standing ovation to all you sheep. JackofOz 23:53, 13 February 2006 (UTC)[reply]

No you don't! Now you're like us! One of us, one of use! ? ?i?ff?? 03:07, 14 February 2006 (UTC)[reply]

I refuse to be cut down to size by the likes of "use". JackofOz 07:52, 14 February 2006 (UTC)[reply]

Whoops! ? ?i?ff?? 09:35, 14 February 2006 (UTC)[reply]

Please learn how to spell properly. That's "Youse". :) User:Zoe|^(talk) 22:21, 14 February 2006 (UTC)[reply]

Actually, the double-plural of "you" would be "yous".JackofOz 10:55, 16 February 2006 (UTC)[reply]

To the original poster: please post concerns like this at the article's talk page (H5N1's talk page is here). Also, you can edit the article about H5N1, so if you think the map is inaccurate, you can replace it with a better one. --Bowlhover 02:11, 14 February 2006 (UTC)[reply]

February 13

Weber's Law

I have been searching for some everyday examples that illustrate Weber's law, can you help?

Have you seen Weber–Fechner law already? --AySz88 ^-^ 02:55, 13 February 2006 (UTC)[reply]

yes I have seen that but I still have not come up with some everyday illustrations of Weber's law.

The example given on the page seems 'everyday' enough to me: "Weber gradually increased the weight that a blindfolded man was holding and asked him to respond when he first felt the increase." freshgavin G??? 15:42, 17 February 2006 (UTC)[reply]

Internet

when was the internet established?

History of the Internet may answer your question. —Charles P._(Mirv) 03:14, 13 February 2006 (UTC)[reply]

Isn't History of the Internet just a redirect to Al Gore? --Kainaw ^(talk) 03:47, 14 February 2006 (UTC)[reply]

Isn't Al Gore enough to explain the misconception regarding many people's inaccurate beliefs about his claims of involvement in the History of the Internet? --Jmeden2000 21:20, 14 February 2006 (UTC)[reply]

Computer Problem Question

I am only able to have dial-up service here in the country - but my laptop is wireless capable. When I stay in hotels my laptop connects to the wireless services but I still can’t get on the internet or get my email through MSOutlook. I believe the problem is that my laptop is some how configured to connect only through the dial-up but I don’t know how to change that. I need to be able to switch back and forth between dial-up and home and wireless when traveling. I hope this was understandable. Thanks for any help you can offer. --63.24.88.70 07:31, 13 February 2006 (UTC)MarCia[reply]

One option would be to just use dialup when in hotels. StuRat 09:05, 13 February 2006 (UTC)[reply]

The wireless network might have some security on it, such as WEP or WPA. As far as I know, however, most wireless networks in hotels don't have inherent security in the packets being transmitted, but implement other measures to prevent you connecting to the internet, even though you are connected to the hotspot. Windows is pretty good at configuring wireless networks automatically when it can. When your laptop says it's "connected" to the hotspot as you say, try these steps:

Right-click on the wireless icon in the taskbar, and click "Repair" to disable and enable the adapter and renew another IP using DHCP (unless you haven't configured it for DHCP, in which case there's a clear reason why it's not working). Keep in mind that this "wireless manager" with the "repair" option is only in SP2.
Now, try a ping test. To do this, open the command prompt (Start -> Run -> type in cmd and hit enter) and do a ping command by typing ping wikipedia.org and hitting enter. If you see messages like "Reply from ......" you're connected. If you see messages like "Request timed out" or "Destination host unavailable" then you're not connected.

But, as always with Wi-Fi, there are many possible problems here. Try speaking to the hotel managers to ask them how to connect. -- Daverocks (talk) 09:19, 13 February 2006 (UTC)[reply]

Chances are, this is a Windows machine. If so, in your dial-up configuration (likely hidden in the "advanced" area) is the option: "Dial up only if network is not available." --Kainaw ^(talk) 03:45, 14 February 2006 (UTC)[reply]

Oh, right, I forgot about that. That option should be under Tools -> Internet Options in Internet Explorer. Mind you, if you used Firefox, that problem would be already solved. :D -- Daverocks (talk) 11:01, 14 February 2006 (UTC)[reply]

Donating to cancer research

I was just thinking about this today: Why do people donate to cancer research? We have so many online donation centers, sponsored runs, cancer research-supporting thrift stores and so on. Surely cancer research is a multi-billion dollar industry, with chemo raking in millions and other drugs raking in who knows how much. More specifically, any pharma company that succeeds in creating a magic bullet cancer drug, or even just any drug that's better than the current standard, will dominate the market and be sitting on a billion-dollar pill. Aren't big-pharma and the investment bankers pouring in more than enough of their own money for what could be an extremely profitable investment? — Asbestos | Talk (RFC) 16:02, 13 February 2006 (UTC)[reply]

Sort of like how people pay energy companies more money inorder to use power from renewable energy plants (wind turbines, solar power, etc).. The power companies are also extremely profitable. People pay to get the companies to do work in areas that are not extremly profitable, like cancer research to a type of cancer that only 12 people have.--Rayc 21:51, 13 February 2006 (UTC)[reply]

As much as we'd like to be optimistic, I think cancer research might be considered a pretty risky "investment" by most. We've been working at curing cancer for quite a while now and, while I'm certainly optimistic, I also don't think it's going to be an immediate thing one day where we suddenly have a cure for cancer. Even if there is a magic bullet out there, I would think investing in cancer research could be like the lottery- obviously very high payoffs, but what are the odds that it will be your pharmaceutical company that hits the jackpot?

As for your typical, middle-class person, many make donations for moral, religious, or tax reasons. Why not donate to something you feel might help thousands of people, including your friend Jack who you saw fight testicular cancer, or your Aunt Betty who passed away from colon cancer? (P.S.- Not real people, just making an example) EWS23 | (Leave me a message!) 02:21, 14 February 2006 (UTC)[reply]

I was just looking at the cancer article, and it's quite good. --Zeizmic 22:25, 13 February 2006 (UTC)[reply]

I was too, though it didn't answer my question in any way. — Asbestos | Talk (RFC) 02:06, 14 February 2006 (UTC)[reply]

Cancer charities do not give money to pharma companies, if that's what you're implying. Nor does most of the money go towards chemo and existing drugs. Why would it? It goes towards all areas. Basic research on cancer (pharma companies do not do basic research), developing new treatments, etc. Before reaching these hasty conclusions, why not check out in more detail what cancer-research money is being used for and what the Pharma companies are using their money for? --BluePlatypus 11:37, 14 February 2006 (UTC)[reply]

As someone who works with charities in this rough kind of area, you don't get much funding outside of personal donations and business sponsership (at least in the UK). We deal with about 20 projects a year with about 5-15 people on each. 4-8 of these are business sponsered. The other's come from public donations. Something of interest is that the big amounts come from will donations. Still give my money to cancer charities each month as people I know have died from it and I want to think I'm helping find an answer. If you look at where we were 50 years ago a lot has been done. More could be done in another 50 years.

Note that it really wouldn't be profitable for drug companies to invent a drug that cured cancer with one pill. In order to break even on the trillions of dollars it would cost, they would need to charge a million dollars a pill. But, since consumers couldn't pay that price, the pill would be copied by others in violation of their copyright. A pill that will only somewhat reduce the symptoms of cancer, instead, could be developed at a much lower cost and sold to patients for years, rather than just once. StuRat 21:31, 14 February 2006 (UTC)[reply]

Pills can't be copyrighted. They can be patented, but luckily (for the people who need cheap pills) patents expire much faster than copyrights. Superm401 - Talk 07:22, 20 February 2006 (UTC)[reply]

Myopia and evolution

In the context of evolution, how is it possible the incidence of myopia and other vision related disorders is so high? I would expect a strong evolutionary selection against them, especially with early people living as hunters etc. --84.41.227.226 16:11, 13 February 2006 (UTC)[reply]

Some thoughts. 1. It may be that there is no genetic basis for myopia; in that case evolution doesn't apply. 2. If it is genetic, eyesight generally worsens as you get older. But any worsening after the children or born isn't relevant to evolution. 3. I'd think you could still be an effective hunter in many modes of hunting with myopia. Digging a pit for trapping doesn't require good eyesight. Even in aiming an arrow at a mammoth, it doesn't matter whether it is fuzzy or clear, it's a target in any case. Notinasnaid 16:36, 13 February 2006 (UTC)[reply]

By the same argument: How can there be any genetic diseases? The answer is that it's not that simple. Genes don't necessarily code for one single thing only. Heterozygote advantage tells you more about this. A text-book example is Sickle-cell disease, a genetic disease common in West Africans. A person can carry the gene without developing the disease. Such a carrier has increased resistance to malaria. This advantage explains how the gene can survive, despite the great disadvantage it puts on the people who develop the lethal disease. It also explains why the gene is uncommon in places like Europe. As for myopia, the article here points to some evidence of higher IQ. So that may be a possible explanation. --BluePlatypus 22:03, 13 February 2006 (UTC)[reply]

I'll have to brush up on this, but as I recall, the incidence of myopia has increased over time and is higher in industrialized societies. Many factors have been blamed, including increased amounts of reading, television watching, and now computer work. I also recall a study showing a link between nighttime illumination (for example, night lights) and myopia, though I don't remember the details. — Knowledge Seeker দ 22:29, 13 February 2006 (UTC)[reply]

Myopia should be higher in societies where it is easily corrected with eyeglasses. But, that is a very narrow view of it. Evolution gets rid of traits that inhibit reproduction. How does poor eyesight inhibit reproduction? Someone who is nearly blind may be left out, but someone who is still able to chuck a spear at an elephant from 40 yards would have no problem finding a mate. In fact, it may be easier since all the blurry women tend to look alike. --Kainaw ^(talk) 03:44, 14 February 2006 (UTC)[reply]

Poor eyesight inhibits reproduction, if it would increase the chance that you are eaten by something that you didn't see before you have much of a chance to reproduce. In most species, most of the animals die whilst they are still young - before they have reproduced. Any trait that is likely to get you killed in infancy is clearly going to inhibit reproduction. That's not to say that some serious genetic diseases won't survive in the gene pool. Some people may carry recessive genes with no ill or detrimental effects - then reproduce and pass on these genes. With eyesight, well perhaps in human societies it didn't matter that much if you were mildly short sighted. Richard B 13:21, 17 February 2006 (UTC)[reply]

I think you guys might be going back a bit too far. First of all, we (those of us in industrialized nations) haven't depended on hunters for our food for a few centuries at least. Farms and domestication replaced the absolute need for hunting long ago. Having markets where people buy food has also helped decrease the number of people who actually hunt for their own food. Then if we accept that large amounts of reading increase the chances of myopia showing up, it would stand to reason that men who made their living by being bankers, lawyers, doctors, etc. would be more prone to myopia than laborers. With these occupations come the ability to afford better health care for their young so that if myopia is genetic, it would be carried on into the next generation with greater ease than by those laborers who may not be able to afford good health care and thus lose children in their infancy. These learned occupations would also lend the workers to be able to attract mates more readily since they could show that they could provide for a wife and children more easily. Combine all this with the idea that glasses haven't ever really been that much of a turn off, and it's no wonder that bad eyes are so common. Dismas|^(talk) 10:01, 14 February 2006 (UTC)[reply]

Notinasnaid, your argument that the children that are born before the onset of myopia will not be affected does not hold up because a parent without myopya will be better at keeping them, and their genes alive, so there will be an evolutionary effect. Dismas, are you suggesting myopia may have appeared only in the last few centuries? That seems a bit too short a timespan for that to develop. But the first point of Notinasnaid was that maybe it's not genetic at all. And it may very well be that myopia is a consequence of lifestyle - too much reading and too little use of the eyes for what they are designed for, namely distances of well over a metre. Also, myopya often appears at ages that are common only now, not during most of the human evolution when people rarely grew older than 40 (I think). DirkvdM 14:24, 14 February 2006 (UTC)[reply]

No, I didn't mean to say that myopia developed in the last few centuries. Only that those who had it were better able to carry on the gene for it. Dismas|^(talk) 18:46, 14 February 2006 (UTC)[reply]

Note that myopia not only makes long range vision worse, but also makes short range vision better. This might have had advantages in tribal societies, where having a few individuals with good short range vision for tool making, sewing furs together, picking insects out of food stores, etc., could aid the survival of the tribe and hence increase the possibility of those genes being passed on. StuRat 21:18, 14 February 2006 (UTC)[reply]

Eye colour in the UK

Are there more people in the United Kingdom with blue eyes or with brown eyes? --OpenToppedBus - Talk to the driver 16:46, 13 February 2006 (UTC)[reply]

Yes. Grutness...wha? 05:48, 14 February 2006 (UTC)[reply]

Looking around the room (I'm in a computer centre at a university), brown eyes seem to be predominant. Hardly conclusive, of course :) GeeJo _{(t) (c)} • 08:58, 14 February 2006 (UTC)[reply]

Blue eye colour is a result of recessive genes. It is therefore usually less common. - Cybergoth 18:54, 14 February 2006 (UTC)[reply]

Except that, as the article states, they are relitively common in Norther Europe. — Asbestos | Talk (RFC) 03:30, 15 February 2006 (UTC)[reply]

And with the UK having such a mix of populations, it's dificult to know for sure, which is why I'm asking! Several people I know who are all pretty good at finding information online have failed with this one - but surely, surely, there must be figures somewhere on relative frequency of different eye colours in the UK. --OpenToppedBus - Talk to the driver 10:49, 15 February 2006 (UTC)[reply]

Relatively common is the key word. I would bet that brown eyes are more common than blue in the UK due to the genetic probability. - Cybergoth 05:39, 16 February 2006 (UTC)[reply]

"Don't it turn my brown eyes blue." - A song about the effects of excessive blueberry consumption. StuRat 21:10, 14 February 2006 (UTC)[reply]

Which tablet PC

Will a 10" tablet PC be good enough for web browsing? I use the PC only for web browsing. Since I am buying a tablet pc, I am confused whether to go for a 10 or 12 or 14 inch tablet? Which one should I go?

Will a 10" tablet (used in same mode as a computer screen portrait or landscape I mean) be good enough for browsing the web or would it be too small or will be a little small or too small?

What resolution does it support (e.g. 640 x 480)? Many web designers expect you to have at least 600 x 800. The size in inches doesn't matter, except that it may mean things get too small to read. But if the resolution is too small the page just won't fit. Notinasnaid 22:36, 13 February 2006 (UTC)[reply]

Nah, most tablets have a decent resolution, even if they're 10" in size. That's because ink strokes look crap if you've got low resolution. enochlau (talk) 00:02, 14 February 2006 (UTC)[reply]

10 inches is really small. Unless you have exceptional eyesight to make out the tiny characters, I suggest a larger screen. StuRat 21:07, 14 February 2006 (UTC)[reply]

It depends on what you're using it for. I've looked at 10.4" tablets, and I think provided the resolution is good enough, they're far more portable than my 14.1" tablet. However, for web browsing, yes, a bigger screen is good. One question you might consider is whether you really need a tablet PC, if all you're going to do is browse the web? They cost a lot more than your average laptop... enochlau (talk) 03:24, 15 February 2006 (UTC)[reply]

Natural/Resonant frequency

I am having trouble finding out whether or not the natural frequency of an object is the same as it's resonant frequency. Logically, they should be the same, but I'm working in complex numbers, and some of the equation's I'm working with show that the natural frequency is not the same as the resonant frequency. My question is, under what condidtions can an object's natural frequency be different than it's resonant frequency?--Rayc 21:45, 13 February 2006 (UTC)[reply]

First mode is called it's natural frequency, and primary resonance. If you calculate the eigenvalues, you will find the other higher-order modes. An object can resonate with many modes, this is a classic issue with earthquakes. --Zeizmic 22:25, 13 February 2006 (UTC)[reply]

February 14

Baked beans

what beans are baked beans?

I think they are common beans, Phaseolus vulgaris. —Keenan Pepper 01:32, 14 February 2006 (UTC)[reply]

Usually they are dried white beans - here is my favorite recipe for baked beans 63.24.1.78 01:51, 14 February 2006 (UTC)MarCia The beans can be made ahead. After cooking, cool them to room temperature and refrigerate in an airtight container for up to 4 days.[reply]

Serves 4 to 6 4 ounces salt pork , trimmed of rind and cut into 1/2-inch cubes

2 ounces bacon (2 slices), cut into 1/4-inch pieces 1 medium onion , chopped fine 1/2 cup mild molasses 1 tablespoon mild molasses 1 1/2 tablespoons brown mustard 1 pound dried small white beans (about 2 cups), rinsed and picked over Table salt 1 teaspoon cider vinegar Ground black pepper

Adjust oven rack to lower-middle position; heat oven to 300 degrees. Add salt pork and bacon to 8-quart Dutch oven; cook over medium heat, stirring occasionally, until lightly browned and most fat is rendered, about 7 minutes. Add onion and continue to cook, stirring occasionally, until onion is softened, about 8 minutes. Add 1/2 cup molasses, mustard, beans, 1 1/4 teaspoons salt, and 9 cups water; increase heat to medium-high and bring to boil. Cover pot and set in oven. Bake until beans are tender, about 4 hours, stirring once after 2 hours. Remove lid and continue to bake until liquid has thickened to syrupy consistency, 1 to 1 1/2 hours longer. Remove beans from oven; stir in remaining tablespoon of molasses, vinegar, and additional salt and pepper to taste. Serve.

Going back to the original question baked beans are the end product of cooking small white navy beans (also called pea beans) or red kidney beans in a recipe similar to the one above. There are hundreds (or thousands) of variations of the recipe so you can spend a lifetime trying to find the perfect baked bean. ;-) --hydnjo talk 03:23, 14 February 2006 (UTC)[reply]

Well I just looked up baked beans on Wikipedia and they seem to think they are haricot beans, so who to believe? --Shantavira 18:39, 14 February 2006 (UTC)[reply]

The common bean article says "white navy bean, also called pea bean or haricot" so there is less conflict here. Rmhermen 20:09, 14 February 2006 (UTC)[reply]

CNN news

I saw a CNN report about a sufi ritual where people pierced their bodies and ate glass ( of a fluorecent light bulb) and they didn't experience any pain ( I don't know about that), and they didn't bleed! ( I saw that) how can someone not bleed at will? this I guess goes against scientific knowledge...what does this mean? I also saw that budhist monks can literally DRY wet sheets just with the heat of their bodies in a cold environment... how many weird things are out there that we don't know about! :S... and just so noone tells me where is the question, the question is, if there is any theory that explains this, or is it just as weird as it seems to me.--Cosmic girl 04:10, 14 February 2006 (UTC)[reply]

Not an answer to your question, but these guys collected ways to say "I can eat glass; it does not hurt me." in different languages. Might come in handy. =P —Keenan Pepper 04:45, 14 February 2006 (UTC)[reply]

Actually, there've been studies alright. They can't "not-bleed at will", they just know, usually, where and how to pierce. I've seen people on TV trying and accidentally piercing the wrong place, and they do bleed, as much as anyone else. Now, the drying wet sheets is not a mystery either. We know today that with proper training, you can control your methabolic rate, induce yourself a fever, change your pulse, blood pressure, everything. There's still a lot we don't know, but it's a fascinating area, since we're finding out our brain has more control of our bodies than we thought. Of course, there's nothing magical in any of this, but we're still just beginning to understand. Additionally, you can train your mind to not feel pain, but there are thresholds where this won't work. ? ?i?ff?? 04:57, 14 February 2006 (UTC)[reply]

The Shaloin monks do all kinds of crazy things similar to what you described. - Akamad 06:58, 14 February 2006 (UTC)[reply]

so... what does this mean? I mean according to Kieff there are studies that show that the brain can control things like blood pressure, and stuff, I already knew that, and also I have heard of cases of people with a multiple personality dissorder changing their neuroelectrical patterns, heart rate facial expresion,and even eye color...but I'm not claiming this is so, I just read it somewhere. but, what does this all mean? this doesn't make sense in a rational world to me, if all this is for real, then our world is...I don't wanna say a curse word...but yeah, if things like this happen, this is not a world that is meant to sustain rational life...since it can and will eventually, drive it crazy...because even if there are experiments that confirm how yoga helps or how monks can do weird things or how the mind can influence the body, we still don't know HOW this happens and that's the important thing...the universe can't be so random...well it can, but I don't like it.--Cosmic girl 14:02, 14 February 2006 (UTC)[reply]

There are lots of things we don't understand, yet they won't "drive rational life crazy" because "rational life" has developed in spite of our strange world and (previous) lack of understanding thereof. It's a lot more robust than you believe. (And what's wrong with a bit of randomness?) Tzarius 21:10, 14 February 2006 (UTC)[reply]

yeah, u are right, randomness is kinda cool, but not when u want something to hold on to...luckily I never wanted such a thing and the previous coment of mine was a burst of stupidity like the ones I use to have sometimes...--Cosmic girl 21:39, 14 February 2006 (UTC)[reply]

It all depends on what you consider natural life to be. Controlling your inner workings doesn't really shock me that much, though impressive. You can interpret it as a crazy manipulation of life itself, but I'd rather think of it as just a plain extension of some other natural functions, like "holding it in", burping on command, making your face red, or dislocating your shoulder. None of these would be considered "the mind influencing the body", but rather as control of the body that we don't usually excercise. freshgavin G??? 05:39, 15 February 2006 (UTC)[reply]

Yes , you are probably right, but then I should be able to cure myself of a feber by will and I don't think I would have any reason to not wanna, since a feber is annoying...so my guess is there's something else here...though I wouldn't like it to be that way, but I'm not the kind of person that seeks to confirm what she wants to believe, but seeks the truth, no matter how pretty or ugly it is.--Cosmic girl 22:30, 15 February 2006 (UTC)[reply]

I do believe you should be able to cure your fever. Just think very hard for a good three or four days and you'll be cured. Good luck! freshgavin G??? 15:35, 17 February 2006 (UTC)[reply]

hahaa! =P, luckily I've never had a fever that lasted for more than 2 or 3 days.--Cosmic girl 19:07, 18 February 2006 (UTC)[reply]

Pain, like color is an interpretation of data. It does not exist in the raw data (uninterpreted reality). It really is all in your head. WAS 4.250 19:48, 18 February 2006 (UTC)[reply]

Wet sheets ALWAYS dry just with the heat of your body in a cold environment. Try it yourself. your body will dry the sheets too. WAS 4.250 19:48, 18 February 2006 (UTC)[reply]

"How many weird things are out there that we don't know about! Is any theory that explains this, or is it just as weird as it seems to me." Most weird things that it seems "we don't know about" are things some human somewhere (usually a poorly paid scientist) has intimate detailed knowledge of, has written a detailed account of, and conforms to known laws of physics exactly. WAS 4.250 19:48, 18 February 2006 (UTC)[reply]

"the brain can control things like blood pressure" Why shouldn't it? WAS 4.250 19:48, 18 February 2006 (UTC)[reply]

"People with a multiple personality disorder changing their neuroelectrical patterns, heart rate, & facial expresion." yes, the same brain wetware can run different programs producing different results just like computer hardware can run different programs producing different computer behaviors. WAS 4.250 19:48, 18 February 2006 (UTC)[reply]

Some eye colors change based on how dialated they are (mine do). WAS 4.250 19:48, 18 February 2006 (UTC)[reply]

"this doesn't make sense in a rational world to me" The world is rational. All humans are nonrational, delusional, and nondesigned. What do you want for an evolved throwaway product? Enjoy life; that's all it's good for. WAS 4.250 19:48, 18 February 2006 (UTC)[reply]

You may be wrong but you may be right I heard this in a song... and maybe the world isn't rational, how are we to know? since you said it yourelf, we humans are deluded. and if all humans are subjective, how can psychiatrists and psychologists have any claim to know sanity from insanity?! the world is just crazy and subjective as hell...--Cosmic girl 21:06, 19 February 2006 (UTC)[reply]

Stress and nightmares

According to the article on nightmares: "In common current usage, the term nightmare refers to dreams of particular intensity, with content that the sleeper finds disturbing, related either to physiological causes, such as a high fever, or to psychological ones, such as unusual trauma or stress in the sleeper's life."

I had an extremely stressful (as well as depressing) day today, so what are the chances that I will have a nightmare tonight? I'm assuming that this nightmare, if I have it, will be related to today's stressful events, correct? --Bowlhover 04:51, 14 February 2006 (UTC)[reply]

We can't tell. You might not have a nightmare at all. Sometimes I have a great day and have terrible nightmares, so I don't see it as a definite connection, but evidently there are cases. I say just do something relaxing before you go sleep, try to distract your attention with something pleasant, and you might drop the chances of having bad dreams. ? ?i?ff?? 05:08, 14 February 2006 (UTC)[reply]

I didn't remember any of yesterday night's dreams, so that's a good thing. I couldn't do anything relaxing before going to sleep because I was in a panic attack (and didn't want to do anything other than sitting still). I got another panic attack after waking up this morning, and am now afraid of having nightmares tonight. --Bowlhover 17:01, 14 February 2006 (UTC)[reply]

Theory of Relativity

I would like to know what is the Theory of Relativity, how to use it and how does it work

Did you look here before you asked your question? JackofOz 07:48, 14 February 2006 (UTC)[reply]

How does one use the Theory of Relativity? Sum0 22:35, 14 February 2006 (UTC)[reply]

With great difficulty, trust me. ;-) In seriousness, it depends what you want to use it for. If you're making the global positioning system work, you use it to calculate the time dilation due to earth's gravity, without which the measured distances to satellites (and therefore the measured position of the user) would be off by several meters. If you're investigating any number of problems in modern physics, relativity is built into your theories. The bending of light in relativity is seen in gravitational lensing, and can be used to make measurements of dark matter. I could go on and on, but I should stop and ask if I'm answering your question. If you want to know how to personally make calculations in the theory, you'll need a solid background in calculus and introductory classical physics, plus a good textbook. -- SCZenz 23:34, 14 February 2006 (UTC)[reply]

Video

What is the tiling artefact in video compression? explain with example. Thanks

I've reformatted your question to make it easier to read. — QuantumEleven | (talk) 08:15, 14 February 2006 (UTC) [reply]

Compression artifact? I'd like to know if we have a detailed article on this particular topic. ? ?i?ff?? 09:56, 14 February 2006 (UTC)[reply]

First human to appear on TV

Our article on John Logie Baird doesn't name him, but there are plenty of sites that say the first human to appear on TV was a 15-year-old office boy named William Taynton, whose image Baird successfully transmitted on 30 October 1925.

But this suggests there were other claimants, namely:

a Mr John Hart
an unnamed doorman at a London club, and
a Mr J E Hamelford, who in 1951 apparently produced a letter from Baird himself that supports this claim. This website is the one and only hit for "Hamelford" on Google. Where might I find any more information about J E Hamelford?

And what ever happened to William Taynton? He would be about 96 now if he were still alive. Does anybody know how his life went after his 15 minutes of fame? JackofOz 08:16, 14 February 2006 (UTC)[reply]

Firs to appear on television in what country? Your options seem to be limited to the UK. - Mgm|^(talk) 19:18, 14 February 2006 (UTC)[reply]

I'm talking about the first human to appear on TV ever, anywhere, in the history of the world. JackofOz 19:48, 14 February 2006 (UTC)[reply]

I take it you're including that British contraption with the spinning wheels that predated the cathode ray tube invented by American Philo Farnsworth ? 21:01, 14 February 2006 (UTC)

There is another clarification... The first person to appear broadcast on television or the first person to have their image shown on a cathode-ray tube? I would expect that the inventor would have stepped in front of the camera a few times while inventing the whole process. --Kainaw ^(talk) 20:55, 14 February 2006 (UTC)[reply]

(revised response after allowing myself to be led astray).

None of these clarifications are necesssary because they are not relevant to my questions. I wasn't asking "who was the first person to appear on television". I was asking "who was J E Hamelford", and "what ever became of William Taynton". JackofOz 23:32, 14 February 2006 (UTC)[reply]

Nothing much became of William Taynton. He appeared on "I've Got a Secret" on Jan 24, 1966. He was not involved in the television invention. He was just an assistant for someone else who happened to be walking by when a human was required to sit in front of the camera. --Kainaw ^(talk) 00:02, 15 February 2006 (UTC)[reply]

Thanks. (I knew about him being an office boy who became an unwitting footnote to history.)

Is he still alive?

Bruce Gyngell was the first person to appear on TV in Australia (this is something that most Australians seem to know; it crops up in quizzes all the time). Do other countries remember their TV first-faces? Is there a list of such persons by country? JackofOz 00:21, 15 February 2006 (UTC)[reply]

Electrical and computer engineering

hello! I am a first year student in the Department of Electrical and Computer Engineering in the University of Patras, Greece. I fell a little bit uncertain about my studies... Can you please tell me if possidle, with what can i occupy myself relatively to my studying subject after ihave finished my studies?? Thank you in advance very much

Are you asking what jobs might be available after you've finished your course, or what you can do to occupy yourself while you're not studying? GeeJo _{(t) (c)} • 09:54, 14 February 2006 (UTC)[reply]

glucose and invert sugar

Hi there! I work in the pastry industry and would like to know more about two products that are very commonly used in the pastry kitchen: glucose and invert sugar. They are considered products derived from chemically-treated or chemically-altered products, and therefore, unnatural. The concern of these products being unnatural is that they might pose a hazard to long-term health. Is this correct?

Neither glucose or invert sugar (a mixture of glucose and fructose) are the least bit 'unnatural'. Glucose is produced by breaking down starch (long glucose chains) into single glucose molecules. The same thing happens in your stomach when you eat starch-containing food like potatoes. It doesn't matter where the sugar comes from though, becuase it is a single chemical compound. Sugar is sugar and it isn't different depending on where it comes from; Unlike everyday objects, molecules don't have any qualities, either it's a molecule of one substance or it isn't. You can't tell two identical molecules apart (even in theory) or tell where they came from. Neither can your body. The term "unnatural" has no actual meaning whatsoever. It's a marketing term, playing on people's aversion to highly-processed food. All the most lethal toxins in the world are 'natural'. --BluePlatypus 11:24, 14 February 2006 (UTC)[reply]

One possible way to differentiate does exist as isotope ratios may differ among differently sourced sugars. But this does not affect biological usability. Practically different minute impurities may be present a sample even if the component is the same. Rmhermen 20:03, 14 February 2006 (UTC)[reply]

Thanks for your answers. So, is it correct to call these produts "chemically-treated" or "chemically-altered" forms of sugar or some type of sugar?? And, more specifically, what are, if there are any, the health hazards related to the use of these products? --70.111.72.88 20:30, 14 February 2006 (UTC)[reply]

The point is, it doesn't matter whether something is "natural". Some "natural" things, like arsenic and uranium, are quite deadly, while some "artificial" things, like water formed in a laboratory from the burning of hydrogen in oxygen, are entirely safe. The only way glucose or invert sugar could be dangerous (other than to diabetics) is if they contained dangerous levels of impurities. I have no reason to think that's the case. StuRat 20:48, 14 February 2006 (UTC)[reply]

The term "refined" is more accurate that "chemically-treated", since it is no more "chemically-treated" than ordinary refined table sugar. Grutness...wha? 21:43, 14 February 2006 (UTC)[reply]

No, it would be very incorrect to call glucose a treated or altered form of sugar. It is sugar. Glucose is the primary form of fuel in your body. Every single cell in your body has lots of glucose in it. Your blood has glucose in it. Your brain can only use glucose as fuel (unlike muscle which can use fat). What you are saying is that, if you take starch and break it down into glucose, the same process done inside your stomach, and do it outside the body, and then eat it, then that is somehow unhealthy? As opposed to eating the glucose contained directly in foods? Every single red muscle cell in your body stores glucose in a form of starch (glycogen), to break down when needed. Typically, you'll have upwards of a pound of glucose stored in your muscles in that form at any given moment. You'll also have about 5 grams of glucose in your blood. The only way not to have massive amounts of glucose in your body is to starve, at which point you'll start burning your own muscle tissue to survive, because your brain can't burn fat. (You'll notice when this happens from an acetone-smelling breath). Have I convinced you that glucose is safe? Ok. So here are the bad points: 1) Glucose, in large quantities, like any food, will make you fat. That is a health risk. 2) Glucose, like all simple sugars, is rapidly absorbed by the body. This is good for quick energy, but bad for appetite. 3) Glucose gives you energy (calories) and nothing else. No vitamins, no fiber. It's what dietists call 'empty calories'. None of this means glucose is a health risk in itself, only that it's not something that you should substitute real food for. --BluePlatypus 21:42, 14 February 2006 (UTC)[reply]

Thank you all very much, you have been very helpful! --70.111.72.88 22:23, 14 February 2006 (UTC)[reply]

Plane wave (Onde plane)

This is a discusstion of a French man and I did. There has been still some questions below:--HydrogenSu 18:54, 15 February 2006 (UTC)[reply]

      *Une onde plane est une chimère ! Ca n'existe pas, sauf a la 
       considerer localement : en effet, une telle onde occupe tout 
       l'espace, ce qui pose des problemes ;-)
         — pem 12 février 2006 à 20:08 (CET)

Exuse-me. Do you mean:Any plan waves exist "locationally" only ? For considering of this question, that's showed us which plan waves occupy all space? But I still don't understand while reading what you said above. I'm sorry for my poor French. I would be speaking English above/below. In fields of physics only,just I'm extremly interested in this question,originally. It has been for several days already and been kept it in mind. I hope someone else can tell more about it.(French or English,either one of them is OK. :) ) J'en suis intéreseé qui la question.--HydrogenSu 13 février 2006 à 19:09 (CET)

I've been waiting a answer for the quetion for 2 days and got no reply almost. I don't know why has no reply in it,maybe he's been busy. But I still care this question. --HydrogenSu 12:42, 14 February 2006 (UTC)[reply]

There were some Wiki problems, and I can't read French or understand your "English" very well, so that's why I haven't answered. I can't speak for anyone else. StuRat 20:36, 14 February 2006 (UTC)[reply]

I have a feeling that you mean plane wave not plan wave, but I don't quite know what you're asking. enochlau (talk) 03:22, 15 February 2006 (UTC)[reply]

<The user:BluePlatypus's comments were nearly off Topic and involved person attacks. Thus it is deleted here.--HydrogenSu 15:49, 15 February 2006 (UTC)>--BluePlatypus 13:00, 15 February 2006 (UTC)[reply]

Try this: let's say you have a wave, continuous in time, x=cos(?t). Then it has a well defined frequency, but it makes no sense to "localize" the wave in time. Consider then the composite function y={0 for t<0, cos(?t) for 0<t<p, 0 for t>0}. Now the wave has a definite position, but the frequency content is widely distributed. You can see this by doing Fourier transforms. Incidentally, Griffiths uses this as an analogy to the uncertainty principle (uncertainty principles seem to appear whenever Fourier transforms are involved). - mako 04:42, 15 February 2006 (UTC)[reply]

The reason is that there is something called the "time-frequency uncertainty principle" - and in a very loose sense, this uncertainty holds intrinsically for any signal. In fact, in this sense, the uncertainty principle in quantum mechanics is not that strange at all! --HappyCamper 13:00, 15 February 2006 (UTC)[reply]

BTY practicing my French----Je ceci te quoi me mercis et je cela lui(user:Mako098765) quoi me mercis.--HydrogenSu 18:54, 15 February 2006 (UTC)[reply]

The French statement above means that a plane wave cannot exist except as a localised approximation, since otherwise it would occupy all of space. This is true: a plane wave is really a spherical wave of infinite radius. When we talk of a plane wave in real situations, what we mean is a small section of a spherical wave; a section that is small enough to have no noticeable curvature. --Heron 20:23, 15 February 2006 (UTC)[reply]

K-40 in body

I once read a science fiction novel that stated that if all the K-40 in your body, by some incredible coincidence, decayed at once, the radiation would kill you. Is this true? -- Pak aran 15:59, 14 February 2006 (UTC)[reply]

Let's find out! According to this, you've got about 140g of potassium in your body. If the abundance is 0.012%, that means 16.8 mg and 420 micromoles. The energy of decay is at most 1.505 MeV, which means the total energy is going to be that times 420*10^-6 times Avogadro's number. Turns out that's 61 MJ. For 70 kg of body weight (which was used estimating the amount of K was based on), that means 870 kGy of radiation exposure (assuming it's all absorbed). That's a huge number, and far more than is needed to kill you. (which is on the order of 10s of Grays) So I'd say: Yes, it seems quite plausible. Of course, what's not plausible is that all the potassium would decay at once. (Calculating the probability of that is left as an excersize for the reader :) )--BluePlatypus 16:51, 14 February 2006 (UTC)[reply]

You could also make this assertion for all the Bismuth in a bottle of Pepto Bismol.

Negro

doesn't this mean BLACK in spannish, as in the COLOR blac, so why do black people act all offended at being called negros, when it's no more or less offense than calling them black?Oto von Boise

That isn't a science question. But first: Most of the time, rest assured that they're not 'acting' offended. They are offended. Secondly, you are confusing the meaning of the word with the connotations associated with it. Third, 'Negro', being a term used during the slavery period in the USA has more racist connotations than the word 'black' and is therefore more offensive. It's as simple as that. Whether the literal meaning is offensive or not is irrelevant to the connotations associated with the word, and is no excuse to offend people by using it. --BluePlatypus 16:59, 14 February 2006 (UTC)[reply]

(via edit conflict) First of all, offense at the term in and of itself is not universal, else the United Negro College Fund and the Universal Negro Improvement Association would have changed their names by now. Secondly, the literal meaning of this kind of term is less important than its connotation (as BluePlatypus notes); the word nigger is highly offensive despite its similar derivation from a word meaning black.

One might as well ask why white and Chinese people should take offense at the terms "whitey" and "Chinaman"—which, after all, mean the same thing as "white" and "Chinese", both terms to which few would take exception. —Charles P._(Mirv) 17:24, 14 February 2006 (UTC)[reply]

Or why anyone would be offended at being ordered to have sex! freshgavin G??? 05:29, 15 February 2006 (UTC)[reply]

Doensn't this depend on where you are? I believe once hearing that 'negro' is the accepted term in the US and 'black' in the UK. Or was that the other way around? DirkvdM 13:07, 15 February 2006 (UTC)[reply]

Don't try that in the U.S. See the Negro and Nigger articles. Rmhermen 19:45, 15 February 2006 (UTC)[reply]

Between "negro" and "black", "black" is the preferred term here in the US, and that's what I generally use. African American is the politically correct, vague, and sometimes incorrect alternative. Superm401 - Talk 07:53, 20 February 2006 (UTC)[reply]

US cable lastmile- fibre or copper?

What do cable operators in USA have in the last mile? Do they have copper or do they have fibre opticals?

If they have copper, then how would it be possible for them to have speedier connections than the same copper which telecom cos have?

If they have fibre, why did they lay fibre even before telecom cos?

We have Comcast. They use copper for the last connection to the house. I believe that all cable companies do the same. As for speed, it is by design, not by limitation on the signal carrying element. For me, I can have a limit set on transfers (upload/download) with cable or a DSL with 3/4 designated for download and 1/4 designated for upload. I prefer to use cable because I download as much as I upload. This is also an issue for online gamers who need bandwidth in both directions. --Kainaw ^(talk) 20:45, 14 February 2006 (UTC)[reply]

While telephone lines and cable TV systems are both copper the similarty pretty much ends there. Telephone lines are point-point runs of low grade twisted pair. Squeezing even the low megabits out of such wiring is quite a feat. Cable TV systems on the other hand use pretty high grade coax which allows much higher frequencies and therefore data rates. However cable TV systems were designed for broadcast data (TV channels) and whilst they have been modified to allow bidirectional data at pretty high rates that bandwidth has to be shared between all the subscribers on a cable segment (possiblly requiring expensive resectioning if to many people wan't large ammounts of bandwidth). Plugwash 01:55, 21 February 2006 (UTC)[reply]

Wive's Tales Question

I would like to know where the statement "the rabbit is dead" came from. Usually this statement is used when someone is testing for pregnancy. If they are pregnant they say "the rabbit is dead", when they are not pregnant they say "nope the rabbit is not dead yet." Some speculate that a long time ago the woman's blood was injected into the rabbit and if it died they were pregnant and if the rabbit lived they were not. Any help on this subject would be great as it is being debated at my office. Thanks a bunch!!!

There is a good write-up on this topic at Snopes: http://www.snopes.com/pregnant/rabbit.htm --LarryMac 18:48, 14 February 2006 (UTC)[reply]

See this article. I simply Googled "the rabbit is dead" + "pregnancy" - Cybergoth 18:50, 14 February 2006 (UTC) (post edit conflict)[reply]

See rabbit test!!! - Cybergoth 18:58, 14 February 2006 (UTC) Doh![reply]

Um, yeah, no kidding, doesn't everyone know that?--205.188.116.74 22:37, 14 February 2006 (UTC)[reply]

Um, no, evidently not. - Cybergoth 04:20, 16 February 2006 (UTC)[reply]

See also The Straight Dope - http://www.straightdope.com/classics/a970704.html

and About.com - http://pregnancy.about.com/cs/pregnancytests/a/rabbittest.htm --LarryMac 18:52, 14 February 2006 (UTC)[reply]

Thanks for your help!! I will now end the debate at the office and educate others, Thanks again. (First time user from Missouri)

Teflon Tubing

Why is Teflon tubing required when keeping a volatile substance under an inert gas like argon?

To make a good seal and prevent leaks? —Keenan Pepper 05:53, 17 February 2006 (UTC)[reply]

If the substance has to be kept under argon, it's likely to be very chemically reactive. So I think this is to ensure that materials in contact with the substance are as chemically non-reactive as possible: both to prevent wastage of the expensive reactive chemical,and avoid losses and leaks from degraded tubing. Teflon tubing fits that specification nicely Malcolm Farmer 12:53, 19 February 2006 (UTC)[reply]

PAL vs NTSC

If I put a PAL VHS tape into a cheap NTSC VCR and hit play, what will I see on the screen? Why? Black Carrot 20:10, 14 February 2006 (UTC)[reply]

In an attempt to show video, the VCR will attempt to sync with the tape. It will do an average job of doing so if it is worth anything. The signal sent to the television will have a sync bar at the wrong frequency, but a worthwhile television will try to sync up with it. Then, it will display the PAL signal as a fuzzy, off-center, gray image. I do not think it will pick up any chroma info to add color. If it did, it wouldn't be correct color and it would not be in the correct location. Please see PAL and NTSC for descriptions of the signals in detail. --Kainaw ^(talk) 20:40, 14 February 2006 (UTC)[reply]

Really...? When I moved from Europe to the US and tried playing my PAL tapes in our new NTSC VCR, we got a grayscale image with sync bars running up the image about twice a second, making it effectively unviewable. You could get an idea of what was happening on screen, but that's about it. Our TV couldn't automatically compensate for the wrong signal, it had to be manually set to receive either NTSC or PAL signals.

Having said that, this was over ten years ago. Maybe signal encoding detection has gotten better over the years, and TVs now auto-recognise signal encoding as a standard feature...? — QuantumEleven | (talk) 08:44, 15 February 2006 (UTC)[reply]

I don't know what you read in my statement above, but I felt that I clearly stated you would see a "fuzzy, off-center, gray image". I also mentioned that the VCR and television would trouble syncing - causing the scrolling effect of the sync bars. That apparently is what you saw.

Now, I have worked with VCRs and monitors that are capable of showing NTSC, PAL, and SECAM. They have a separate circuit for each. They did not auto-switch. You had to manually select the format. I liked the VCR. It had a map of the world and you pressed the country the tape originated from. Then, it switched to the format for that country. --Kainaw ^(talk) 18:21, 15 February 2006 (UTC)[reply]

I really should read comments more carefully - confusion arises from skim reading! Thanks for the poke, Kainaw, as it turns out we were describing exactly the same thing, down to the manual switching between PAL, NTSC (both versions) and SECAM. Doh! — QuantumEleven | (talk) 13:57, 16 February 2006 (UTC)[reply]

You got grayscale because PAL encodes the color differently (that's what the "A" stands for -- it "alternates" to reduce the effects of noise, so an NTSC set sets it averaging out to gray). The sync failure would be because European TV has 25 frames/second while US TV has 30 (Europe has more lines per frame, so the overall quality is similar). There is no technical problem making a multisystem TV or VCR, there just isn't any significant market for them in North America, so normal consumer products are NTSC-only. --Anonymous, 10:22 UTC, February 15.

Help with Measurement

File:P2101777.JPG

Experimental setup

I have more than 50 such photos from my experiment. I want to measure the slope (angle with horizontal/vertical) of the end plate on the left for each of these photos. I also want to measure the length of each of these tubes. How can i do this in a convenient way (or how can I do this at all)? I have at my disposal softwares like Photoshop, Illustrator, Matlab, GIMP, Paint, Photo Editor, etc. Thanks! deeptrivia (talk) 20:37, 14 February 2006 (UTC)[reply]

If you want to measure them manually:

Use a protractor to measure the angles relative to the picture edge. However, if the photos are randomly oriented, then this only gives you the relative angles of the two ends, not the absolute angles of each.

Use a string to measure the length of each tube by placing it on the centerline then measuring the string with a ruler. StuRat 21:44, 14 February 2006 (UTC)[reply]

I think ol' triv-man wants something lazier. I looked it up, and commercial GIS software all has this functionality. However, I can't find out much about the state of open source GIS, just this link [[14]] Some drawing packages might have a poly-line length measurement. In that case, you would lay on a spline curve, and have it calculate length. --Zeizmic 23:36, 14 February 2006 (UTC)[reply]

On Adobe Photoshop there is the Measure Tool. This is in the same box as the Eye Dropper tool on any fairly modern version. On my version (Photoshop CS2) when I draw with the Measure Tool up at the top of the screen it lists the x and y positions of each point, the relative heighth and width change, and the angle, listed under 'A'. If you don't see this on an earlier version, you should still find the angle by drawing with the Measure Tool and selectiong Image>Rotate Canvas>Arbitrary, and the angle will appear in the box that comes up. — Asbestos | Talk (RFC) 12:49, 15 February 2006 (UTC)[reply]

If you try it, you should find that the angled plate is about 33 deg from horizontal/ — Asbestos | Talk (RFC) 12:51, 15 February 2006 (UTC)[reply]

Herbert W. Boyer

Hi, My nephew, a freshman in high school who plans to be a doctor is doing a paper on Dr. Herbert Boyer (Genentech founder Herbert Boyer, former professor of biochemistry at UCSF) and needs to know his date of birth. Dr. Boyer was born in 1936. We know that from a number of WEB sites. However, I cannot find the exact date and would appreciate it if you knew the month and day. Thank you very much. His paper is due 2/21/06 so the sooner I get that information the better. Thank you. Pat Hersom

Our article on Boyer doesn't say anything more than the year... have you considered actually contacting Genentech, or at one of his alma maters (erm...almae materis?)? Grutness...wha? 00:51, 15 February 2006 (UTC)[reply]