Wikipedia:Reference desk/Science

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February 1

What about February 1st? This question no verb--152.163.100.74 02:17, 1 February 2006 (UTC)

The date header is added (as a level 1 header) to provide a navigational convenience by date. Please don't change it (and it is not a question). -- Rick Block (talk) 02:59, 1 February 2006 (UTC)

But if February 1st 'was' a question, what question would it be? Hmmmmm??? --Anonymous and silly, 04:05 UTC

"What is one half of the Ultimate Answer to Life, the Universe, and Everything?" - 21! EWS23 | (Leave me a message!) 04:42, 1 February 2006 (UTC)

I've never understood why we call our article that. What do we mean by "the answer to life" (etc)? Douglas Adams wrote about "The Answer to The Ultimate Question of Life, the Universe and Everything". JackofOz 08:00, 1 February 2006 (UTC)

I suppose you could suggest a pagename change to The Answer to The Ultimate Question of Life, the Universe, and Everything, which might be more correct. I'm not sure if a decision was made long ago to shorten the actual title, considering the bolding at the top of the page is identical to what you just quoted. Perhaps they decided to go with the shorter name and figured it didn't matter as long as all the redirects work properly. EWS23 | (Leave me a message!) 17:47, 1 February 2006 (UTC)

It seems more likely that the page was originally created with that title, and no-one ever got around to changing it. You could post a move request at WP:RM for it; I can think of no reason to oppose such a move. —Ilmari Karonen (talk) 21:34, 1 February 2006 (UTC)

Thanks, I'll do that. Cheers JackofOz 00:57, 2 February 2006 (UTC)

As usual my memory doesn't serve me well, but thinking in the context of the story I'm pretty sure that the first mention of The Answer was just as The Ultimate Answer to Life.... It wasn't until they had the answer that they started looking for the question, and then they started talking about the answer not just as The Answer, but as The Answer to the Ultimate Question... (to emphasise the fact that the question was almost as important as the answer). That being said, the article is strange though, with the article space and the title different as it is.   freshgavin TALK    01:16, 2 February 2006 (UTC)

Birth Control Pills

What would happen if a man took birth control pills for women? Would there be any kind of disruption of hormones?

• he might be able to get pregnant, for reference, please see the featured article Male Pregnancy, for more details--152.163.100.74 03:58, 1 February 2006 (UTC)

Taking oral contraceptives would cause a disruption in hormones, particularly estrogen and progestin. While probably not identical to the doses used in oral contraceptives, the article on [Hormone Replacement Therapy for transgender-transsexual male-to-female] may be a good starting point for learning about the potential effects of a man taking BC pills on a long-term basis. --Uthbrian (talk) 04:03, 1 February 2006 (UTC)

Of course it would "disrupt hormones". Birth control pills would suppress your gonadotropins, lower your testosterone level, raise your estrogen level, shrink your 'nads and grow you some mammaries. But it's your bod. alteripse 05:09, 1 February 2006 (UTC)

I do remember this case report where some dude was drinking his girlfriends' urine (they all took the pill) and eventually presented at the hospital with gynecomastia. H. Vierhapper, P. Novotny, Lancet 1999, 353, 640. Pilatus 05:16, 1 February 2006 (UTC)

Apparently many kg of excreted OCPs enter the water system of every major city each day. OCPs are the most pervasively detectable pharmaceutical agent in the environment. alteripse 05:24, 1 February 2006 (UTC)

Splenda/Equal/Sweet+Low and Tooth Decay

Do Splenda, Equal, or Sweet and Low cause tooth decay like sugar?

Splenda = sucralose; Equal = aspartame; Sweet and Low = saccharine. So no, no, and no. - Nunh-huh 05:38, 1 February 2006 (UTC)

Are you suggesting that they're not bad for the teeth because they're not sugars? That's a rather wild assumption. Anything synthetic (assuming that they are) is something that the body hasn't adapted to in evolution and is therefre likely to have some negative effect (possibly in the long run). Whether the teeth will be affected is a different matter, but assuming they won't is a bit of a stretch. DirkvdM 11:51, 1 February 2006 (UTC)

No, I'm stating that they don't "cause tooth decay like sugar". You (the one who doesn't know whether or not they are synthetic), are the one making wild inappropriate logical leaps here, not I. In the case of sucralose, there were a series of actual studies demonstrating it didn't cause tooth decay, which is the reason the FDA approved it. - Nunh-huh 13:43, 1 February 2006 (UTC)

Dental caries has a nice gross picture. The synthetic sugars could rot other parts of your body, but the little bugs that chew on your teeth need natural sugars. --Zeizmic 13:08, 1 February 2006 (UTC)

Decay-causing oral bacteria require sugars for their nutrition. Non-nutritive sweeteners such as Splenda do not provide nutrition-- either to humans or to oral bacteria; they do not promote tooth decay. Equal (aspartame) is, technically speaking, a nutritive sweetener-- but oral bacteria do not have the capability of metabolizing it, and it does not cause tooth decay. And Sweet 'N Low, while predominantly composed of sodium saccharin, also contains lactose, which is nutritive, but in such low amounts as to make it for all practical purposes non-nutritive and non-cariogenic (does not promote tooth decay).--Mark Bornfeld DDS 14:52, 1 February 2006 (UTC)

why eye focus changes light colour

When looking at certain light sources and changing the varying the focus of one's eyes, it is possible to notice a change in the percieved colour of the light. For example, a white light will appear yellow if underfocused (focal point behind source). What causes this phenomenon? -nshty mcnshterson 88.144.34.107 06:56, 1 February 2006 (UTC)

I'm not an opthalmologist or any sort of eye expert whatsoever, so I can't give a good answer to your question. However, I just tried this myself, and I didn't notice any yellow at all. My experiment involved holding a small black plastic object close to my eye, focusing on it, with a white piece of paper behind it, unfocused. To me, the white paper remained white. The best answer I can give is that the yellow you are seeing is an afterimage of something else you may have looked at previously. However, I might be wrong. -- Daverocks (talk) 11:32, 1 February 2006 (UTC)

I tried it too and didn't notice anything. I used a lightbulb as a source because you say 'certain light sources'. Which ones? I thought that maybe the soure has a yellow hue, but when the background is dark the contrast will make it appear as white. But of course that has nothing to do with fodus (has it?). Could you be more specific (also known here as "suitly emphazi") so we can reproduce the experiment more precisely? DirkvdM 11:58, 1 February 2006 (UTC)

There is something called spherical aberration which causes the outer edge of a lens to act like a prism. This might have something to do with it.

Astronomy

I am studying in 10th class in India and want to have a carreer in Astronomy. So please suggest want I should do next year.

Physics and maths, and make sure your English is good? enochlau (talk) 08:01, 1 February 2006 (UTC)

You can check the criteria for admissions into Indian Institute of Astrophysics from its official website. Also the Indian Space Research Organisation has several centres, you can go to the official ISRO site. Jay 09:59, 1 February 2006 (UTC)

See also, Tata Institute of Fundamental Research, Inter-University Centre for Astronomy and Astrophysics, Indian Institute of Science. They would all have good Astronomy departments. But right now, focus on Physics and Maths. deeptrivia (talk) 14:14, 1 February 2006 (UTC)

In India, you cant specialize in Astronomy at this early stage. It would be a good idea to do your 11th and 12ths with Physics, Chemistry and Maths. That way you'll be eligible for all Engineering and Physics courses for the undergrads. I'm a final year Physics Undergrad from India, I'll specialize in Condensed Matter Physics. But, as far as I can see, I still have the option of going into Astronomy open. So, doing a B.Sc. with a Physics major might be an option for you? Where are you from?--Sayanchak 16:12, 1 February 2006 (UTC)

Remember that while popular consumer astronomy is all the pretty visual pictures of the heavens, real astronomy includes radar and other non-visual aspects of the electromagnetic spectrum. Many nations are active in space. Is India one of them? User:AlMac|^(talk) 01:20, 2 February 2006 (UTC)

Yes, it is. See Indian space program. That said, they are different fields with only a certain degree of overlap. --Robert Merkel 11:23, 2 February 2006 (UTC)

Keyframes in video

Q :What is importance of keyframe in video encoding? —The preceding unsigned comment was added by 202.138.120.37 (talk • contribs) .

(heading inserted) enochlau (talk) 08:01, 1 February 2006 (UTC)

According to the article Key frame: in video compression, a key frame is a frame encoded without reference to any images in another frame.

So, one advantage of key frame is that it prevents encoding errors from accummulating over time. It kinda has a "refresh" effect in terms of video quality. The trade-off is that more data bits are required to encode that frame. I'm not sure if there are any other advantages. --Vsion 11:29, 1 February 2006 (UTC)

Keyframes also make seeking faster, since the player doesn't need to process all frames before the current frame to find out the state of it. With keyframes evenly spaced, you'd just need to start seeking from last keyframe up. ☢ Ҡieff⌇↯ 12:40, 1 February 2006 (UTC)

A little clarification to help you understand the above answers. Most frames (in mpeg, anyway) are defined in terms of other frames. Oversimplified, if a piece of the image doesn't change from one frame to the next, you don't need to record it twice but just say 'do that again'. But since video is real-time, keeping up with the tempo is more important than getting the image exactly right. So errors are allowed. If you wouldn't 'reset' every now and then you'd get an ever increasingly garbled image. By the way, lossless compression like mjpeg is better for video editing because it has all the frames complete (it's a sequence of complete jpeg images), so you can create a cut at any frame, not just a key frame. The big drawback is that it requires much bigger files. DirkvdM 12:41, 2 February 2006 (UTC)

One quibble: I really doubt that MJPEG is lossless, as it's based on JPEG which is lossy. rspeer / ɹəədsɹ 20:20, 3 February 2006 (UTC)

Doctor advice

Okay, let's say your a doctor and a teenage girl is having seisures, what sort of stuff would you do to find out what is wrong? Blood tests? X Rays?

Take her to a doctor who doesn't need to ask the Wikipedia reference desk for advice :) — QuantumEleven | (talk) 12:17, 1 February 2006 (UTC)

It depends. If you are seeing her have a seizure in front of you, you can see what kind of seizure it is, and treat it if needed. On the other hand, if she comes into your office and tells you she has been having seizures, you discuss what kind of seizures they were, with her and with anyone who may have seen her having an actual seizure; you discuss her medical history, and perhaps her family history. A physical and neurological examination is in order. Blood tests might be useful, but in the absence of a severe electrolyte abnormality, they are not likely to determine a cause for seizures. A CT-scan or MRI of the brain might be of use; an EEG might be of use, but the first step is a good history of the illness: determining if the illness is actually seizures or something else, and if so, what type of seizure (e.g. generalized or partial) they may be. - Nunh-huh 12:19, 1 February 2006 (UTC)

Thanks for your help Nunh huh, but QuantumEleven, I'm not a doctor, I'm just very interested, I'm 13, might be more careful how you answer

I apologise - my remark was flippant and didn't really help to answer your question. Next time, I'll keep my mouth shut, or at least say something constructive... — QuantumEleven | (talk) 13:02, 1 February 2006 (UTC)

Take a look at our article on seizures. There are several possible causes that must be analyzed. ☢ Ҡieff⌇↯ 12:36, 1 February 2006 (UTC)

I tend to agree with the flippant advice, if this is one of those 'my friend has this' situations. If you have witnessed a seizure of a young friend (or yourself), it is not 'ratting' to talk to an adult, or to see a doctor. --Zeizmic 13:18, 1 February 2006 (UTC)

And talking to an adult might be especially important if you think she might be using drugs or unprescribed medicine, as that is certainly a potential cause of seizures in a young adult. - Nunh-huh 14:02, 1 February 2006 (UTC)

I think QuantumEleven was just making a joke, maybe not in very good taste, but i thought it was mildly amusing when I saw the :) at the end.

Woah, woah woah, I don't have a friend or anything with this problem, I'm just interested because I'm a teenager and I'm doing RPGs on doctor stuff and I'm interested in what would help recover or find out what is wrong

I don't believe the first priority would be blood tests or x-rays, though a doctor might do some of that too. You'd probably suspect that the subject became epileptic due to some sort of trauma (like smashing your head on a sink) and so you'd want to look into the brain (like a brain MRI or EEG) to see if you can find something wrong, as well as asking if the patient had smashed her head into a sink in the last white (or something like that). I'm not sure but I don't think a doctor can be 100% sure of their analysis unless they actually scan a seizure event. There are other causes but that's by far the most common, I'd say.   freshgavin TALK    01:09, 2 February 2006 (UTC)

Did you look up seizure and epilepsy? You will find most of your answers there. First of all, the doctor would need to determine that the "seizure" was in fact an actual seizure (and not syncope or a pseudoseizure for example). An EEG could help confirm that there had been a recent seizure. Blood tests would be useful to determine if there was a metabolic disorder causing the seizures (for example, renal failure, hypoglycemia, etc.). A CT scan or MRI could determine if there was a structural cause (eg. a brain tumor) for the seizure. Cybergoth 03:30, 2 February 2006 (UTC)

Statistics on Computer Science degrees

Where's the best place to start looking for statistics about how many people have received degrees in computer science (BSc, MSc, PhD, etc.) per year since, say, the 1980s? --Fastfission 12:55, 1 February 2006 (UTC)

• Actually... nevermind! I found this page just after posting this. --Fastfission 12:57, 1 February 2006 (UTC)

Sneeze

Why do adults sneeze so much louder compared to children, or compared to when they were younger? It seems to get louder as one gets older. Thanks. 69.234.27.124 13:59, 1 February 2006 (UTC)

Possibly because the average size of the lungs, sinuses, etc. is larger would be my guess.... Dismas|^(talk) 14:10, 1 February 2006 (UTC)

Though this counts as original research, I think that since adults tend to try to 'hold in' sneezes it actually amplifies the effect of the sneeze; holding it in can build up the 'explosive force' of the sneeze. Me on the other hand, I rarely ever lose control of my sneezes and I can hold them in quite easily, and it still feels almost as good as an orgasm!   freshgavin TALK    23:43, 1 February 2006 (UTC)

I wonder what the religious right would make of that. Should you go to hell? Or is it okay if you and your nose are of different genders? Black Carrot 05:38, 5 February 2006 (UTC)

Alternative to organ donation?

Am I right in saying that the biotechnology of cloning is now advanced far enough to be able to take an individual's cell sample and grow up a new organ, eg heart, liver, lung etc. If so, both donor and recipient would be histocompatible. This therefore potentially solves the problem of looking for donor organs, and the drudgery of renal dialysis for kidney failure patients etc. Or, is this type of human organ cloning currently illegal in the UK ?

You can grow cell samples in culture but that's a long way from growing complete organs. I think the only way to get a complex organ like a heart or lung is to grow a whole human being in a woman's womb. —Keenan Pepper 15:28, 1 February 2006 (UTC)

The chances are that people are working hard on this and that it will one day be possible. The rewards (both financial and medical) are enormous, so billions will be spent on research. I wouldn't count on much in less than 10-20 years, except for skin (a really important organ: think of burn victims). I suspect livers will come among the first. Other internal organs later; limbs after that. Brain cells are the really interesting one. Even if illegal, that isn't really relevant: if research is legal anywhere it will take place, then there would be huge public pressure to make it legal so people can get their new bits. Notinasnaid 17:12, 1 February 2006 (UTC)

You might be interested in this recent article from the Washington Post. Among other things, it mentions the possibility of growing entire human organs inside other animals. However, this (and almost everything that is in that article) has at least some sort of moral debate attached to it that might slow down research, especially in the United States. - EWS23 | (Leave me a message!) 17:58, 1 February 2006 (UTC)

This is one of the reasons that research into stem cells is so popular at the moment, because they are the undifferentiated cells that, given the right signals in the embryo, turn themselves into the various organs. Of course, there are ethical dimensions that send certain parts of the population into a tizzy. --Robert Merkel 00:09, 2 February 2006 (UTC)

Ah, given the right signals in the embryo. That's what I wanted to say. How the cells differentiate is determined by their biological surroundings and for that you'd need almost a complete human (or animal as EWS23 says - didn't know that). Well, almost complete. I've heard about the solution of growing a human clone without a brain, which thereofore has no conscience and there wouldn't be any moral problems (...) with 'harvesting organs. But I see one big problem here (correct me if I'm wrong - I am by no means an expert). To avoid rejection you'd want to have as close a relative as possible, in other words, preferably a clone of yourself. But then, when some accident happens and you need an organ you can't usually wait for that to grow. And cloning everyone at birth, just in case, would be a bit too much (for now, anyway). So it might only be used for people with some medical problem that will probably require a transplant later in life. DirkvdM 13:06, 2 February 2006 (UTC)

Starting PHP

Hi,

I want to start learning PHP, but I have a couple of questions that I have not been able to find answers to:

• Can I use PHP as a stand-alone programming language on my computer? That is, do I need a server and database and stuff, or can I first program something on my computer (windows and mac) and then move it online?
• (Related) Would I have to change my program if I moved it to a different type of server or database program?

Thanks! --Mary

PHP is a pretty good interpretted language in itself. You can run PHP scripts, just the way you run any other script. And they wont need to be changed, when you decide to switch to GNU/Linux for example.--Sayanchak 16:01, 1 February 2006 (UTC)

• Wikibooks has a book on PHP. --JWSchmidt 17:47, 1 February 2006 (UTC)

Thanks. What if I want to develop a website which will eventually need a server, database and all that. Can I still just program it right in my computer, without access to an online database? --Mary

You can program it, but you can't test it locally if you don't have a database. Of course, you could always install a database (such as MySQL) locally along with Apache. --Pidgeot (t) (c) (e) 18:53, 1 February 2006 (UTC)

Running PHP locally can be done by installing a web server like Apache, which is free. If you are using a Mac with OSX, it already is installed. Basically.. install Apache; install PHP; install MySQL (or whatever database you want). All are free and all can be run from your home computer.

As for portability: it depends on the setup of the server. Each installation of PHP can have different settings. If the settings are the same, programs can be transferred without any difficulty. If they aren't, then you will have problems. An easy way to see the settings is to install PHP and then create a file called "info.php" which contains just the following line: <?php phpinfo(); ?>

It will output a page like this: http://www.entropy.ch/software/macosx/php/test.php

The most important settings are to make sure that any libraries you need (i.e., the GD library for image processing, or the PDF library for PDF-related functions) are installed. There are some other issues too (i.e. whether variables passed to a script through a GET protocol are immediately available or whether they have to be assigned from $GET) but at this point you shouldn't worry about them. Long story short: it can be portable, but it might need some tweaking. If the project you are working on requires a specific optional function library, make sure the server you are intending it for will support that.

Hope that helps a bit. --Fastfission 20:04, 1 February 2006 (UTC)

New scientific article

I'm in the process of hammering out a new article - Remotely triggered earthquakes. Does anybody have the same writer's block that I do? It takes me forever to start. I hammer things out directly on-line, then I format, and wikify, add outside sources, and then add links from other articles. Once I do it, it's fine, but it's just getting in to it that is so difficult. --Zeizmic 17:20, 1 February 2006 (UTC)

A little help ... same for me!

(Note to Firefox users: There is a useful toolbar just for editing wiki pages.)

I open as many pages as I need for references + the Help:Editing page. I save once or twice to have the idea and read again (misspellings appear easily in a different font!)

What I suggest is a search feature in the edit forms! Good luck! Take care! --DLL 20:24, 1 February 2006 (UTC)

It's very common for writers and composers to shrink from the act of sitting down and committing their ideas to paper. Having great ideas is one thing, but the spectre of having to write all those words/notes is most unattractive. So just getting started is often a huge challenge (it is for me). That first word is often the hardest of all. The good news is that this barrier can be overcome by writing - one word. JackofOz 20:33, 1 February 2006 (UTC)

I periodically print out the pages I am working on. I circle words and phrases in different colored pens to indicate links found, what should be linked but not yet found article that matches that phraseology, right topic different naming, etc. User:AlMac|^(talk) 21:32, 1 February 2006 (UTC)

SKIN DISEASE

There's a skin disease that makes a person's skin lihter. It literally can change a black skin into a white skin. It perhaps also makes the skin extremely sensitive to the sun light. What is this disease called? Scientific name and other please.

Vitiligo? —Ilmari Karonen (talk) 17:32, 1 February 2006 (UTC)

Exactly what I was going to post. Michael Jackson claims that's why his skin is lighter than it used to be. User:Zoe|^(talk) 17:34, 1 February 2006 (UTC)

He also claims that it's not so strange that he's white (and his kids are white) because African-americans are sometimes called colored people because that they come in many different colors, and by his reckoning, white!   freshgavin TALK    05:35, 2 February 2006 (UTC)

Albinism is another condition you might be interested in. It's a lack of pigmentation in the eyes, skin and hair. However, it's much more of a genetic thing and a lot rarer than vitiligo, but still worth a look at. -- Daverocks (talk) 09:47, 2 February 2006 (UTC)

And it doesn't start developing when you become famous either!   freshgavin TALK    10:05, 2 February 2006 (UTC)

Nope, it doesn't. Therefore Michael Jackson is not affected by it. -- Daverocks (talk) 06:03, 3 February 2006 (UTC)

"Michael Jackson is the ultimate example of social mobility in America; he started life as a poor black boy and ended up a rich white woman. He still likes to play with little boys, however." StuRat 00:45, 5 February 2006 (UTC)

How do you know it's bedtime at Michael Jackson's house? When the big hand touches the little hand. Black Carrot 05:36, 5 February 2006 (UTC)

They would be lucky if only their hands were touched. StuRat 15:34, 5 February 2006 (UTC)

Brain and Food

When you are getting ready to eat a piece of pizza describe in detail what parts of the brain are involved and why?

"Do your own homework - if you need help with a specific part or concept of your homework, feel free to ask, but please do not post entire homework questions and expect us to give you the answers." Please review the instructions at the top of the page. To start on answering your question, I'd suggest reviewing our article on the human brain and following links from there. TenOfAllTrades(talk) 18:51, 1 February 2006 (UTC)

Sorry for the inconvience,this does not pertain to homework. I am a late thirty's, father of four and this was the topic at our dinner table while eating pizza last night. I was trying to get some insite in order to discuss this further with my inquisitive eight year old son whom asked the question.

Lol. There's a lot of these homework accusations flying around, although I must say it did smack of a homework question! Sorry I can't help... --Username132 23:23, 1 February 2006 (UTC)

Let's see. In order to pick up the pizza and get it to your mouth, you have to process the image from your eyes and recognize it as pizza, which involves the visual cortex. Then you have to actually pick it up, which involves using your motor cortex to send signals to your muscles.

When you smell the pizza, the amazingly complex olfactory system sends a signal, perhaps through the amygdala and the parasympathetic nervous system, which eventually gets to your salivary glands and tells them to start making saliva. The parasympathetic nervous system also tells your stomach to start making acid and the smooth muscles of your intestines to get ready to digest the pizza.

After you've used your motor cortex to tell your jaw muscles to chew the pizza, your medulla oblongata kicks in with the swallowing reflex. I'm sure I've missed quite a lot of things, but you get the picture. —Keenan Pepper 00:01, 2 February 2006 (UTC)

Apart from the obvious motor activity involved in eating, there is the complex interplay between endocrine and neural function that is behaviorally expressed as hunger and satiety. Various sensory and endocrine parameters (e.g., visual and olfactory input, blood glucose and insulin levels, degree of stomach distension, levels of hormonal peptides such as gastrin, and cholecystekinin) are translated by the hypothalamus into either a sensation of hunger (attributed to the lateral hypothalamus) or satiety (the ventromedial hypothalamus). Of course, all the sensory input is also conveyed through its own pathways, which include the thalamus and the sensory cortex as well.--Mark Bornfeld DDS 00:55, 2 February 2006 (UTC)

Providing Oxygen To Domestic Boilers

How is it ensured that enough air gets into a domestic boiler for gas to burn with a blue flame, whilst at the same time heat loss is minimised? --Username132 19:40, 1 February 2006 (UTC)

Hi 132 - I'd guess the important factor is to have a good heat exchanger on the exit flue, so that all the heat produced is transferred to the water pipes - MPF 20:28, 1 February 2006 (UTC)

Ok, for sure this is homework! I actually love it when the originator comes back and denies it. Shows that we have reached out and touched someone. That said, this is really the most classic combustion engineering problem, and is a major engineering challenge in designing clean EPA wood stoves. I looked it up because I want to buy one... --Zeizmic 21:55, 1 February 2006 (UTC)

Well, sure enough here I am, and you're right, I deny it! I'm a student at Durham University reading Biomedical Science and we don't actually do much combustion engineering, at least not in the third year! (just curious) Thanks, though! --Username132 23:19, 1 February 2006 (UTC)

CSS/JS table hiding

I am exporting a database to an HTML file in the form of tables. The basic structure will be something like this:

 
 <table>
 <tr><td>Entry 1 title</td></tr> 
 <tr><td> <table><tr><td>Entry 1 data</td></tr></table></td></tr>
 <tr><td>Entry 2 title</td></tr>
 <tr><td> <table><tr><td>Entry 2 data</td></tr></table></td></tr>
 ...
 </table>
 

and so forth. What I want is to create a little button or something which will cause the data to be shown or hidden via Javascript. I assume this will involve setting some sort of DIV tag or something on the fly. I once knew how to do this but now I'm not so sure.

Any tips as to where to start? If you give me a basic area to pursue I'm happy to do the research on my own. I don't think this should be too difficult but the details elude me. --Fastfission 20:48, 1 February 2006 (UTC)

I use this stock code:

var ie4 = false; if(document.all) { ie4 = true; }
function getObject(id) { if (ie4) { return document.all[id]; } else { return document.getElementById(id); } }
function DisplayTable() {
  var d = getObject("table");
  if (d.style.display == 'none') { d.style.display = 'block'; }
  else { d.style.display = 'none'; }
}

Then you just make your table id="table" and use the js function DisplayTable() to hide/show. ☢ Ҡieff⌇↯ 20:57, 1 February 2006 (UTC)

Bar of Tungsten

Where could i get a free sample of Tungsten? Or even one for a very low price as it would be very helpful for my A Level physics project in which i am investigating Tungsten.

The guy who created this website has acquired a number of samples of tungsten over the years. They vary quite a bit in terms of size, shape, purity, and cost, but might give you some ideas—he's listed his sources for most of them. Depending on what you're planning to do, you might be able to beg or borrow a sample from a local university materials science or metallurgy department. TenOfAllTrades(talk) 22:12, 1 February 2006 (UTC)

A metal dealer should be able to supply that for you, and quite possibly for free, if it's a small enough amount. Given that they usually trade in rather large amounts, it'd may not be worth their while to bill you for it. On the other hand, it's a rather expensive element, currently running $260 per MTU, (Metric Ton Unit) which is a mere 10 kg of WO₃, and even less in terms of pure tungsten. --BluePlatypus 22:17, 1 February 2006 (UTC)

Could you explain what an MTU is? We don't seem to have an article on it. —Keenan Pepper 22:50, 1 February 2006 (UTC)

It's here, and it's 1000kg.   freshgavin TALK    23:39, 1 February 2006 (UTC)

That doesn't make sense. How can a metric ton be 10 kilograms? —Keenan Pepper 00:11, 2 February 2006 (UTC)

I think what Blueplatypus is trying to say is that you can buy some industrial product (I'm not sure what) for $260 per 1000kg, and from that you can extract 10kg of WO₃, and less than 10kg of tungsten. You wouldn't really be paying $260 just for the tungsten... though I'm not sure why he mentioned that figure. I don't know how easily tungsten can be obtained in a pure form though.   freshgavin TALK    00:56, 2 February 2006 (UTC)

Tungsten is measured in Metric Ton Units of tungsten trioxide. In this context is actually 1% of a metric ton (quite misleading!), that is 10 kg of WO₃. So only 7.93 kg of actual tungsten. Google for "Metric Ton Unit tungsten" or similar. --BluePlatypus 02:09, 2 February 2006 (UTC)

Edit confliect! I was just going to say that. In particular I suggest looking at Russ Rowlett's excellent dictionary of units of measurement. A "metric ton unit" is simply 10 kg, and it has that name because it's the amount of metal you can extract from a metric ton of ore if the ore contains 1% metal! (I am not making this up.) --Anonymous, February 2, 2006, 02:13 UTC

If you want a (very small) free sample of tungsten, smash a domestic light bulb—the filament is made out of tungsten. Physchim62 (talk) 02:27, 2 February 2006 (UTC)

What the hell : (. What could the benifit be of using such a unit? (And giving it such a confusing name.) Why don't they just admit that if you have a metric ton/tonne of ore, and the metal content is 1%, you can extract 1% of 1 ton/tonne of metal (e.g. 0.01 tons/tonnes)?   freshgavin TALK    05:33, 2 February 2006 (UTC)

• The straightforward way is to order from a fine chemical supplier. Aldrich and Strem are the best known; depending on which country you live in there may be others. They sell the material in all shapes (powder, wire, sheet and bar). Be warned, though that the stuff is expensive. It's also brittle and highly refractory and thus difficult to work. Pilatus 05:37, 2 February 2006 (UTC)

Myspace Music Help

For some reason, my settings on firefox will not allow me to access MySpace Music (http://music.myspace.com/index.cfm?fuseaction=music). It also won;t allow me to access it on Internet Explorer. Can anyone help? I will be able to provide answers to any questions that could help solve this. Thanks M@$+@ Ju ~ ♠ 21:47, 1 February 2006 (UTC)

I can access it ok. If it's both browsers, it might be some ad blocker, or a firewall somewhere along the line. You accessing it from work or home? enochlau (talk) 23:19, 1 February 2006 (UTC)

From home, and I don't think it's an ad blocker issue, because I keep a pretty tight watch on that. I'm wondering if my browser's security settings might be to blame, because once I turned off SSL 2.0, TLS 1.0, and SSL 3.0 (all of which are currently ON), and I was able to see a banner, but not the main page. Much thanks if that helps you figure out my problem. M@$+@ Ju ~ ♠ 23:38, 1 February 2006 (UTC)

If you're unable to access it properly with either browser, I'd say it's probably a problem outside of the browser settings. But I don't really know what it could be. If you can access other websites successfully, then there's no reason why MySpace Music shouldn't work, unless it tried connecting through a different port which might be blocked, which is unlikely to be possible unless some plugin is doing it... I'm rambling now, ignore me. :) By the way, SSL and TLS aren't firewalls or anything like that, they just encrypt the data you send on secure websites (like online banking), and MySpace Music clearly is not a secure (HTTPS) site, like most websites. -- Daverocks (talk) 09:59, 2 February 2006 (UTC)

It is a strange prediciment, but thanks for trying guys. It's not too big of a deal I guess, but it would be nice to know what the problem was. Thanks. M@$+@ Ju ~ ♠ 20:23, 2 February 2006 (UTC)

What is a feeling of apprehinsion tension or uneasiness that stems from antcipation of danger, the source of which largely unknown or unrecongnized

Paranoia? —Keenan Pepper 23:31, 1 February 2006 (UTC)

Spider-sense!   freshgavin TALK    23:36, 1 February 2006 (UTC)

Isn't it "spidey sense" ? StuRat 00:41, 5 February 2006 (UTC)

Anxiety. Frencheigh 23:43, 1 February 2006 (UTC)

According to the American Phychiatric Glossary (via Google books; direct links there won't work, right?), anxiety is "Apprehension, tension or aneasiness from anticipation of danger, the source of which is largely unknown or unrecognized." Frencheigh 02:13, 3 February 2006 (UTC)

The word is dread, folks. alteripse 00:30, 2 February 2006 (UTC)

I'd say that 'dread' is usually associated with a known fear, e.g. I dread the day I have to leave home. As an unknown sense I think plain anxiety or paranoia makes more sense.   freshgavin TALK    00:49, 2 February 2006 (UTC)

What about "foreboding" or "disquiet"? JackofOz 00:54, 2 February 2006 (UTC)

According to admittedly hoary information from my behavior pathology class 33 years ago, the distinction between fear and anxiety is that fear is attached to a particular idea or object, while anxiety was a generalized, free-floating state of arousal/agitation unattached to any specific object. It is a sensation that is described as ego-alien, or something that is perceived as unpleasant and acknowledged as abnormal by the subject. As for paranoia, that is a completely different situation-- an ego-syntonic (perceived by the subject as factual and real) delusional perception of persecution, and a symptom of psychosis.--Mark Bornfeld DDS 01:13, 2 February 2006 (UTC)

• Howabout 'forboding? M-W.com: "to have an inward conviction of (as coming ill or misfortune)".--Fastfission 01:21, 2 February 2006 (UTC)

(already suggested - see above)

Speaking existentially, anguish or angst? Or existential despair? Sum0 15:23, 2 February 2006 (UTC)

• I don't know the word off the top of my head, but I'm certain that there is one in Douglas Adams' The Meaning of Liff. TenOfAllTrades(talk) 21:26, 2 February 2006 (UTC)

I am surprised that nobody has yet mentioned sense of impending doom. 217.208.26.85 23:54, 3 February 2006 (UTC)

English Convention for Titling Subjects

I was wondering what the reasoning is behind using uppercase for the first letters of most words, and lowercase for words like of, the, and...? --Username132 23:52, 1 February 2006 (UTC)

This question really belongs on the Wikipedia:Reference desk/Language page. JackofOz 23:54, 1 February 2006 (UTC)

I find that the more uppercase there is, the harder it is to read quickly. So why capitalize totally unimportant words and just make the title harder to read? It doesn't draw attention to anything important to capitalize Of. — Laura Scudder ☎ 00:01, 2 February 2006 (UTC)

For those of us whose eyesight had a hard time distinguishing between a period and a comma, the capital letter at the start of a sentence is a good backup. User:AlMac|^(talk) 01:25, 2 February 2006 (UTC)

Check out Capitalization#How to capitalise - there are many different styles of capitalising headings and titles, and which one you use depends on your personal preference, house style, country and more. On Wikipedia, we set up a 'house style' for capitalising headings and titles, read all about it in Wikipedia:Capitalization#Headings and Wikipedia:Manual of Style (headings). — QuantumEleven | (talk) 08:50, 2 February 2006 (UTC)

What do you mean by 'capitalisation of most words'. Just read the prose here and you'll see that only one in about 20 words or so are capitalised. DirkvdM 13:30, 2 February 2006 (UTC)

Although it wasn't stated in the posted question, the section heading for this question mentions that this question refers to Titles. Johntex\^talk 18:13, 2 February 2006 (UTC)

extacation of caffeine from coffee

the chemistry experiment extraction of caffeine from coffee. after using the separating funnel for extraction why do we discard the dark brown aqeous layer in the funnel

From the Caffeine article:

Caffeine will migrate to the solvent in which it is most soluble, and it is more soluble in chloroform than water. —Keenan Pepper 00:05, 2 February 2006 (UTC)

• Damn, we just used benzoic acid when our lab did it, removing caffeine from coffee should be considered a federal crime, decaf... *shudders*--64.12.116.74 00:07, 2 February 2006 (UTC)

February 2

Music of the Spheres

Do planets like earth make different sound vibrations,like harmonic sound?

Have a look at our article Musica universalis. JackofOz 00:48, 2 February 2006 (UTC)

Johannes Kepler used to believe in this stuff. He actually published it in 1619, in the same book in which he postulated his third law. Titoxd^{(?!? - help us)} 01:19, 2 February 2006 (UTC)

Sound is vibration of air. Lack of air around planets means there is no sound. Audible sound has frequencies between 20 and 20.000 Hz. Planetary movements are much slower. Of course you could take the various cyclic planetary motions, speed them up to our audible range and play that on a synth. I've once heard the sound of trees in a BBC documentary, which was recorded and then speeded up to make it audible. It was almost rhythmical (except there was no regular beat). DirkvdM 13:35, 2 February 2006 (UTC)

The earth does vibrate, at frequencies too low to hear [1]. Sadly though, "this sound is not particularly pleasant or enlightening - in fact it sounds like a bored person banging a garbage bin lid very loudly." Mark¹ 15:47, 2 February 2006 (UTC)

All the scientists made a mistake; it is a bored person banging a garbage bin lid very loudly.   freshgavin TALK    04:20, 3 February 2006 (UTC)

Avian Influenza genus and species

After researching for the genus and species of Avian Influenza, I am not sure if I have found the correct answer. The information I have found does not list the genus and species together. I have found that the genus is Influenza A, but not the species. Avian Influenza I have found is commonly referred to as H5N1 and is considered a sub type of Influenza A. Would the correct list of genus and species for Avian Influenza be Influenza A H5N1?

00:46, 2 February 2006 (UTC) 24.15.160.72 00:49, 2 February 2006 (UTC)

See H5N1 and Influenzavirus A. Try using the search box on the left of the page next time, you'll get an answer much quicker. --Robert Merkel 01:35, 2 February 2006 (UTC)

.rar

Just wondering, I just downloaded a .rar file of just under 15 MB in size, unzipped it only to find that it contained a 400 MB file! I've never heard of any compression system that works quite 15 MB!">that well on rar archives, does anyone know how that might work?--Rar-contributer 02:27, 2 February 2006 (UTC)

RAR uses a very good (but slow) compression algorithm. --Kainaw ^(talk) 02:40, 2 February 2006 (UTC)

Also, there are certain types of data that can be compressed rather well. Additionally, if the RAR contains several slightly different versions of the same file, and they're all compressed in a solid format (that is, they're all compressed as a single chunk of data), then the extra redundancy can be cut off tremendously. The extracted files, however, will be pretty big anyway. ☢ Ҡieff⌇↯ 02:47, 2 February 2006 (UTC)

Imagine that you have to compress a photo taken with the lens cap on. It might be 8 MB, but many compression systems could reduce it to a few KB, because it is all a repetition of the same, black, colour. This is an extreme case, but graphics with repetition are good candidates for astonishing amounts of compression. Notinasnaid 11:49, 2 February 2006 (UTC)

Some data compress really well. For instance, a megabyte worth of binary zeroes compresses to only 1051 bytes using gzip, or 45 bytes using bzip2. Ten megabytes worth of binary zeroes compress to 49 bytes using bzip2; a hundred megabytes, to 113 bytes. Obviously, your data doesn't compress as well as pure binary zeroes. --cesarb 14:22, 2 February 2006 (UTC)

I firmly believe that pure binary ones will compress even more efficiently, because they stack better (at least in a sans serif typeface). Zeroes contain a small amount of incompressible space in their holes. TenOfAllTrades(talk) 21:22, 2 February 2006 (UTC)

That's why the smart people who invented the "Fixedsys" font put the disambiguating diagonal strikes through the zeros, not only to distinguish it from an "O" (a letter of the alphabet), but also to let all the air out. ;) -- Daverocks (talk) 06:08, 3 February 2006 (UTC)

bluetooth

ooth

Please suitly emphazi your question. —Keenan Pepper 04:39, 2 February 2006 (UTC)

You might be interested in our article on Bluetooth, or our article on the Dreamlands, a fictional location from H.P. Lovecraft's Dream Cycle, where the valley of Ooth-Nargai is located. EWS23 | (Leave me a message!) 04:51, 2 February 2006 (UTC)

the ooth is out there. Grutness...wha? 06:32, 2 February 2006 (UTC)

• That'd be Harold I of Denmark. --BluePlatypus 20:27, 2 February 2006 (UTC)

If you have a blue tooth, you might want to consider eating fewer blueberies and/or brushing your teeth more often. :-) StuRat 03:01, 4 February 2006 (UTC)

Return of the penis

Why does a penis rise while having sex? —The preceding unsigned comment was added by 210.211.225.56 (talk • contribs) .

Um... try our article on erection? Titoxd^{(?!? - help us)} 07:02, 2 February 2006 (UTC)

You should answer questions with statements, not more questions.   freshgavin TALK    10:03, 2 February 2006 (UTC)

Even if using the socratic method? Notinasnaid 11:03, 2 February 2006 (UTC)

No? DirkvdM 13:40, 2 February 2006 (UTC)

Employing the Socratic method in the bedroom could be pretty interesting. GeeJo _{(t) (c)} • 18:30, 2 February 2006 (UTC)

What did I start? Titoxd^{(?!? - help us)} 23:50, 3 February 2006 (UTC)

While having sex? How do you start without an erection? Or don't you mean coitus specifically? Enough counterquestions for you? DirkvdM 13:40, 2 February 2006 (UTC)

Well, how do you define sex? EWS23 | (Leave me a message!) 17:57, 2 February 2006 (UTC)

Sapphists shouldnt have that problem, and frottage and Cunnilingus don't require an erect penis. GeeJo _{(t) (c)} • 18:19, 2 February 2006 (UTC)

"S2,3,4 keeps the penis off the floor." - Cybergoth 03:23, 3 February 2006 (UTC)

I think Bill Clinton has fully explored the disingenuity of the theory that sex = penetration. JackofOz 03:28, 3 February 2006 (UTC)

Avoiding pacemaker rejection

What is done to avoid the body's immune system treating an artificial pacemaker as a foreign body and creating anti-bodies to reject it ? Jay 08:03, 2 February 2006 (UTC)

Immunosuppressive drugs are the most common technique. -- Daverocks (talk) 10:05, 2 February 2006 (UTC)

I actually had checked out the Immunosuppressive drug article. It talked of natural organ translpants, but there was no mention of artificial organ transplants. Will the case with artifical be a lot different ? Jay 12:48, 2 February 2006 (UTC)

The chemical makeup of the casing is so designed that it will rarely cause problems. The whole thing will not be rejected, and will be encapsulated by scar tissue, in the same way a piercing is. -- Ec5618 11:21, 2 February 2006 (UTC)

Can you give some link to this ? I would like to add all this to the article. Jay 12:48, 2 February 2006 (UTC)

Immunosuppressive drugs are not used when mechanical devices (or even non-living biomechanical devices such as a porcine heart valve) are implanted. Such devices do not provoke a Type IV hypersensitivy immunological response. - Nunh-huh 20:02, 2 February 2006 (UTC)

Oh. Whoops. I guess I shouldn't talk from now on, considering I'm not a physicist physician. Must stop getting my words mixed up. -- Daverocks (talk) 06:11, 3 February 2006 (UTC)

The outser casing of pacemakers is often (usually?) made of titanium, which is very inert in the body. It is also used for joint replacements and some dental prostheses, for the same reason. Physchim62 (talk) 20:55, 2 February 2006 (UTC)

Petroleum rock deposits

With what rock type(s) are petroleum deposits generally associated?--67.173.252.120 08:37, 2 February 2006 (UTC)

Shale is a major one - have a look at oil shale. Grutness...wha? 10:15, 2 February 2006 (UTC)

Oil is always associated with Sedimentary rock, as opposed to igneous rock or metamorphic rock. That said, a lot of oil companies pay a lot of money to find out precisely where the black gucky stuff actually lives. --Zeizmic 00:35, 3 February 2006 (UTC)

Data Recovery

I desperately need to format all the drives of my computer but I have some important data(occupying a space of about more than 1.5 GB) stored in my computer. I need to start over again with a new installation of the operating system after completely formatting all the drives. I do not have a CD writer hardware so copying the data to a CD is impossible and the data is VERY IMPORTANT and I do not have a backup.Is it possible to upload the data to the Internet or is there any other way I can create a backup? I do not exactly know what is uploading. Please explain the term and whether it can be a solution to my problem. Please explain in detail the solution to my problem. Please help me! Please help me! Thank you!

Probably the safest option is to buy a new disk and install the system to that. Once it is done, you can (with some juggling of hardware settings) add the old disk and read the data from that. Better still, buy an external CD drive that plugs into your computer. Backups are very important, and disks can fail at any time, without warning. Happens here all the time. Notinasnaid 12:26, 2 February 2006 (UTC)

Well, he says 'all hard drives', which is plural, so I'd say put it all on one drive, format the rest, install your new OS, copy to a formatted drive and format the remaining drive. If you don't use backups it's especially important to physically unhook the drive with the data on it in case you make a mistake specifying the drives to be formatted (maybe that's what you were asking for). It is also advisable to unhook all other drives when installing the OS, especially when it's msWindows, because that can give a lot of headaches in my experience. Of course, backups are a very good idea and a cd or dvd writer doesn't cost too much. DirkvdM 13:48, 2 February 2006 (UTC)

I would also recommend you buy an external CD- or DVD-writer - they're not that expensive, you can easily hook them up to your computer (usually through a USB port), and the case of a DVD drive, you can fit all your data on a single disk. Echoing Notinasnaid and DirkvdM, if your data is as important as you say, it is very strongly recommended to make backups somewhere that is not your PC. Imagine what would happen if, for instance, you spilled coffee all over your PC. Or a water pipe broke and flooded the room. Or a fire broke out - these things can and do happen. CD or DVD backups are relatively cheap and easy.

In case this solution is not possible / not practical for you, you could get a friend with a laptop to help you, connect the two computers up with a network cable, and back your data up on your friend's computer. Then, when you've reformatted your PC, you can move the data back by the same way.

Backups over the internet work in a similar way, except you are copying your data to a computer which is connected to yours through the internet. The problem is finding one which will offer to host your data - your ISP (the company you connect to the internet through) might be able to help you. Many of them offer "web hosting" (which is basically a bit of space on their server where you can upload your files), but most only offer several tens of megabytes, too small for your purposes - but ask. Sure, you can get more space, but it will probably cost you and is unlikely to be worth the hassle if you're just backing up your data once. — QuantumEleven | (talk) 14:01, 2 February 2006 (UTC)

I'd echo what's been said above, and strongly recommend acquiring a CD or DVD writer; they're useful things, and you can do regular backups for the future. Another option is to go out and buy a portable USB drive of some sort. Looking at the website for my local computer shop, I can buy a 2 GB USB flash memory device for as little as 120 dollars (Canadian); that's a shade more than a hundred bucks U.S. They're handy for moving data around, too. TenOfAllTrades(talk) 21:09, 2 February 2006 (UTC)

I'd recommend an external hard drive. I paid £60.00 for an 80GB one last month.Theresa Knott | Taste the Korn 21:29, 2 February 2006 (UTC)

Software program for creating "20 questions" game

I'm looking for a program where young students (5th-7th grade) could easily and inutitively program a 20-questions-like game. Basically, once they've written it, it should produce an output such as "Vehicles: Does it have wheels? 'Yes.' Is it big and yellow? 'Yes.' It's a school bus!", or whatever.

If such a program could be created by drawing a decision tree this would be ten-times better, but either way, is there anything out there like this? — Asbestos | Talk (RFC) 12:23, 2 February 2006 (UTC)

IMO it might be borderline for the age group, but you could teach them a very simple programming language like BASIC, which supports decision trees (by means of IF-THEN statements as well as the dreaded GOTO).

Something I'm not entirely clear about - do you want the computer do the guessing ("does it have wheels?", "is it big and yellow?"), or do you want the computer to reply to the guesses made by the students? In the former case, the decision tree would have to be gargantuan (possibly covering every known object), or the student's "unknown word" would have to be limited to a known, small set. In the case of the latter, you would have to restrict the questions the students can ask it, otherwise it will get confused very quickly. I'm just wondering... — QuantumEleven | (talk) 13:49, 2 February 2006 (UTC)

There's a commercial version of the "computer guesses" variant - see http://www.radicagames.com/20q-cb.php. According to http://www.radicauk.com/20q_howitworks.htm, it uses a neural network approach, likely to be far beyond the capabilities of 5th-7th grade students. -- Rick Block (talk)

Right. I'm neither looking for the students to create a 20Q game for all possible objects, nor, hopefully, for them to have to do any programming. This would be more along the lines of giving them 10-20 objects/events/whatever, and having them create a decision tree with them in the most intuitive way possible. Any other suggestions would be great. — Asbestos | Talk (RFC) 21:37, 2 February 2006 (UTC)

This is a branching database isn't it? I have a program at work but I can't remember the name. I'll try to remember to post it here tomorrow. Theresa Knott | Taste the Korn 21:25, 2 February 2006 (UTC)

This reminds me of an old story I read in an anthology of science fiction, sorry that I can't remember the author. The program should say:

• • "Welcome to 20 Questions, I am thinking of a person, place, thing or idea. Enter your guess, or type 'quit' to end."
  • The program should then take the input provided, drop the question mark at the end, and examine whether the last letter is an "e" (or any other random criteria you choose, for that matter).
  • If the question ends in "e" or matches the criteria, answer "Yes". Otherwise, "No".
  • The logical human mind will take care of the rest, because a person will typically not ask a question that contradicts a previous question, therefore they will "create" a unique object in their mind based on the random answers given. When they are satisfied that they have found the object, they will type 'quit' to end.

I know that doesn't really answer your question, just interesting. But playing the game the other way (Computer-asks) was one of the early example uses of the Lisp programming language, known (if I recall) as ANIMAL or ZOO. here is one (strange) online adaptation. I don't know if anyone has come up with a way to do this graphically, but this computer science professor claims that his "On-line Decision tree system to graphically illustrate Guess-the-Animal" is "Forthcoming (by Oct. 1999)."

KWH 13:08, 3 February 2006 (UTC)

Thanks, that last link was interesting, though it's a pity the program that looks relevent is, as you note, "forthcoming"... — Asbestos | Talk (RFC) 17:21, 3 February 2006 (UTC)

You might try emailing him (see the link at upper right, "Eric Siegel", then check the bottom of that page). Seems rather friendly. KWH 03:58, 4 February 2006 (UTC)

cutting the umbilical cord

Is cutting the umbilical cord painful to the newborn and/or mother ? Does it result in blood loss ? How do all other mammals cut the cord and how do they manage to control the blood loss ? Jay 12:57, 2 February 2006 (UTC)

See parturition. The umbilical cord is made of Wharton's jelly, not ordinary skin and connective tissue. There are no nerves, so cutting it is not painful. There is ordinarily no significant loss of either infant or maternal blood unless something goes wrong. I am not certain of the range of variations of placental and cord structure in most other mammals, but suspect that it either shrivels and falls off (like the stump of umbilical cord of a human baby) or is consumed by the mother (which recycles the protein, and reduces tissue that would attract scavengers or predators). alteripse 15:19, 2 February 2006 (UTC)

For animals: the mother bites the cord apart, and it dies and falls off after a short while.

Albert Einstein and an article inconsistency?

An anonymous user posted a comment on Talk:Albert Einstein stating that there is a factual inaccuracy in the article.

Wikipedia's own articles point out that Henri Poincare discovered Relativity, and David Hilbert first published on Novemer 20, 1915 the famous Field Equations of general relativity which completed that theory. Reference See Einstein-Hilbert action. Also, the so called theory of general relativity is only a theory of gravity, which should be pointed out. Thus, Einstein's Introduction on Wikipedia must be re-written. User:69.22.98.162

I'm not familiar with the detailed history of the theory. Could someone knowledgeable in the area go take a look? Thank you very much! By the way, is there a good book on the history of relativity out there? --HappyCamper 13:05, 2 February 2006 (UTC)

This idea was covered many months, if not years, ago on the talk pages here. An anonymous user tried to accuse Einstein of plagarism. It may be the same person. It is certainly true that Einstein's work built substantially on those who had gone before, and that Poincare and Hilbert both made significant advances in what might be called Relativity. Who exactly 'discovered' it is one of those questions that depends on exactly what you mean by Relativity. What is certainly true is that Einstein was fully deserving of the praise he eventually got for the discoveries he did make. DJ Clayworth 19:52, 2 February 2006 (UTC)

Read the top of Principle of relativity, which is what Henri Poincare invented according to our article. It says that the principle is not the same as the Theory of Relativity. The anonymous user is confused; perhaps our articles should be clearer. -- SCZenz 05:54, 3 February 2006 (UTC)

PEPPER

Please give me a brief history of Pepper and its effects on humans who consume a lot of it ie its side effects if any.

Have you read our article on black pepper (or, for other kinds of pepper, pepper)? In fact, it's such a good article that it was a featured article! — QuantumEleven | (talk) 14:14, 2 February 2006 (UTC)

Hey, they now put a magic search box in the preamble! --Zeizmic 21:24, 2 February 2006 (UTC)

darn, now it's gone.. too much pepper for me.. --Zeizmic 21:27, 2 February 2006 (UTC)

Spam

Two years ago Bill Gates said he would kill spam within two years. Apart from a few laws and a handful of prosecutions, have there been any significant advances towards this end? --Shantavira 14:54, 2 February 2006 (UTC)

Bill Gates' ideas for a "postage cost" for e-mail has met with stiff resistance and is very unlikely to be implemented. We have made, however, significant progress in e-mail filters (see mail filter), to a point where a good filter can screen out about 60% of incoming spam. Also, people are slowly learning the rules of the net, such as not posting your e-mail address on public forums, or using several addresses for different purposes. However, all this is receiver-side stuff, very little has been accomplished on stopping the miscreants sending spam in the first place (save for a few arrests and trials, such as Jeremy Jaynes). Spam continues to be a large problem for the e-mail backbone, as something like 88% of all e-mail sent is spam, and while it may not reach its intended destination, it still clogs up the networks to a huge extent. I'm not completely up to date on the latest findings, but I don't see any breakthroughs in the fight against spam happening anytime soon. Which is a depressing thought. — QuantumEleven | (talk) 15:06, 2 February 2006 (UTC)

And unfortunately spam is moving into other areas. Every connection you have that is open to random calls will be a target for spam. For example, the monopoly phone company did a good job of stopping mass callers, now with IP phones, this protection may be gone. You can completely stop all spam by only allowing encrypted connections from people on your list, but then you'll never get that call from your rich lost uncle. --Zeizmic 21:22, 2 February 2006 (UTC)

And how much of that progress was thanks to Bill?   freshgavin TALK    04:14, 3 February 2006 (UTC)

I don't see how Gates could have any effect on it (let alone eliminate it). About 10% of my email is spam,and only because a few years ago I have been a little careful with my email address (the one and only email address I have had over the last few years, without any filtering at all!). Not broadcasting your address or otherwise making it available to people or organisations you don't have any serious dealings with is the only way to go. Unless there will be some (international) law against it. And since people apparently don't learn from the mistakes they've made over the years, government intervention seems to be the only solution. By the way, what bothers me is the phone spam I get every few days. The big difference is that with email spam (1) I decide when I'm exposed to it (2) it's instantly obvious it's spam, I remove it and I'm done with it. So even though email spam is more frequent it irritates me much less. DirkvdM 10:53, 3 February 2006 (UTC)

See also the Userfriendly comic strips on 2006 Jan 30, 31, 32. – b_jonas 11:44, 4 February 2006 (UTC)

Anatomy-Directional References

Anatomical terms of location? - Nunh-huh 19:54, 2 February 2006 (UTC)

medicine/alpha adrenergic receptors

do alpha adrenergic receptors influnce on the level of potassium in blood?

thank you in advance, ivan

Yes. See this article. - Nunh-huh 20:15, 2 February 2006 (UTC)

Cells staff

What is meant by "multi-cellular"?How are cells able to live side by side? What do cells "eat"? What 2 roles do DNA play in running and maintaining the cell? What materials have to enter the c4ell and what would you expect the cell to give out? What do vacuoles fo?How are they different in plant animal cells?

We don't have a specific staff just for cell questions. We also generally don't answer homework questions directly. LarryMac 20:22, 2 February 2006 (UTC)

However, you might want to look at the article Cell (biology) to get some help. LarryMac 20:45, 2 February 2006 (UTC)

See also DNA, cell respiration, vacuole. Please try typing search terms into the search box on the left side of your screen before you bring your questions here. TenOfAllTrades(talk) 20:52, 2 February 2006 (UTC)

Why do u think this is homework question?

People generally become quite skilled at recognising a homework question. For example "What 2 roles do DNA play in running and maintaining the cell?": if someone was just curious, they wouldn't know there were two roles; if someone was reading an article, it would mention the roles. That leaves a question someone expects you to answer: homework, or a quiz. Doesn't look like quiz material. Of course people can also be wrong. So, if we are wrong, let us know why you want to know, beyond what the references have already said. "Why you want to know" isn't just being nosey: there are very different kinds of answers you might need, depending on whether (e.g.) you are trying to understand an article, write an essay at 12 year old school level, or are studying medicine at university; also a full answer would be dozens of pages long, and most people are too lazy to type that much, so they want to know where to focus. Notinasnaid 15:28, 3 February 2006 (UTC)

Verification of the existence of the Academy (automobile)

Can anyone verify that the Academy (automobile) really existed? If you really feel like helping, can you suggest a source for other cars added by the same user? All the best and thanks for any help. Mozzerati 21:51, 2 February 2006 (UTC)

• Google works. "academy car coventry 1906" gives a number of hits, enough to make me believe the thing did exist. Some other randomly-chosen entries by that user seem to check out as well. From the edit history, it looks like he's going through a list of cars, perhaps from some book. I'd be more worried about copyright violations in that case. --BluePlatypus 23:48, 2 February 2006 (UTC)

• • Thanks.. it was the 1906 that I was missing. My google searches came up with useless junk ... hmm.. clearly not equipped for the bright new future Mozzerati 22:07, 4 February 2006 (UTC)

Pterasaurs: Bird brain? Brain dead?

I am posing this question for a friend of mine. There is a lot of thought put into it, and we hope that an answer or some insight can be found.

• I've been studying pterosaurs recently, and only after much searching have I found a fairly complete reference with ANY real mention of pterosaur brains. Though I'm not done with the pterasaur skull chapter, what I have read so far indicates that braincasts of at least PTERODACTYLOID pterosaurs were similar to birds in that the cerebral hemisphere was fairly large. Are there any experts or newbies like me who can put their two cents in on their opinion on pterosaur brainpower? I'd really like to hear the latest word on this. Also, I know that brain to bodysize ratios are important in guessing if an animal is intelligent. Is size just a factor? Or is weight as well? Anything anyone knows or guesses is extremely appreciated.

Thanks from us both. M@$+@ Ju ~ ♠ 23:02, 2 February 2006 (UTC)

I'm certainly no expert in this field, but I do know of a book which might be of interest to you (assuming it's not the one you say you've found). Try to track down a copy of The illustrated encyclopedia of Pterosaurs by Peter Wellnhofer (Salamander Books, London, 1991, ISBN 0861015665). It goes into a fair amount of detail on pterosaur anatomy, incuding a small section of comparative brain anatomy between pterosaurs, birds, and reptiles. Grutness...wha? 23:45, 2 February 2006 (UTC)

Thank you, I will pass the advice on to my friend. M@$+@ Ju ~ ♠ 02:38, 3 February 2006 (UTC)

For a fairly simple modern discussion of the topic, there's David Unwin's new book on pterosaurs: Unwin, D. 2006.The Pterosaurs From Deep Time, Pi Press, New York. The most recent paper I know of, using CAT scans and all the bells and whistles is: Witmer, L. M., Chatterjee, S., Franzosa, J., and Rowe, T. 2003. Neuroanatomy of flying reptiles and implications for flight, posture and behaviour. Nature, 425, 950-953. John.Conway 03:00, 3 February 2006 (UTC)

I notice that a Google Scholar search with such terms as pterosaur brain skull returns quite a few hits, so you might try a few searches of that type if you haven't already done so. --DannyZ 08:22, 5 February 2006 (UTC)

February 3

Question

+ File:Trichlórmetán.jpg =  ?

Hah, what a great question. ☢ Ҡieff⌇↯ 00:35, 3 February 2006 (UTC)

$NaOH+CHCl_{3}->?$

Hmm...don't remember any more. deeptrivia (talk) 00:58, 3 February 2006 (UTC)

Adding a base to chloroform will form dichlorocarbene, which is a fairly reactive species. I'm not certain it'll cause that large an explosion though! If you're after an "Oops, I made a bang in my Chemistry Lab", go for Ammonium hydroxide and iodine crystals. If you slosh the resulting Nitrogen triiodide onto any surface and leave it to dry, it'll make a quite satisfying bang (and nasty iodine stain) if anything touches it. Even a feather'll set it off. As always, see Wikipedia:disclaimers before giving it a go. GeeJo _{(t) (c)} • 01:00, 3 February 2006 (UTC)

It can be explosive, yes, especially as the NaOH pellets helpfully contain about 20% water which would quench the carbene rather too rapidly. Physchim62 (talk) 01:09, 3 February 2006 (UTC)

Whenever I see that detonation picture, I don't see the explosion, I see a man in a lumberjack jacket bending down. --Sum0 16:24, 3 February 2006 (UTC)

• Yeah, a lumberjack welding a railroad track. Poor guy, he has to work two jobs to make ends meet. Johntex\^talk 16:52, 3 February 2006 (UTC)

How to build a mechanical arm???

My school has a project due on Febraury 21, 2006. My partner and I are supposed to build a Mechanical Arm. It has to raise a normal #2 pencil up 1 meter. We have a great idea and everything, but we have no idea on how to start and what to use. We have been looking for hours for an idea, but everything is about a the sergical arm for people with problems. You know!!!!! I was wondering if you could maybe explain to us how to start, what to use, and help us understand how to do it. We would like to make it a decsent one so we could get a great grade. We can't have a crane to raise it up and down (so i think) so we have to use a button. Can you tell us where to go to get the materials and everything that has to do with our problem. And if you would like to add what ever you want to help us out would be appreciated. (hin,hint) (lol) We want to thank you for your help!!!!

sincerely, --68.104.161.148 01:43, 3 February 2006 (UTC)

Dear anonymous, to answer this kind of question it helps to know what level of education you're referring to; a suitable answer for an primary (elementary) school student is not the same as for a university engineering school student.

That said, some general advice; the details of the rules of the challenge matter greatly. To give an example, to win a paper plane distance contest, a standard "cheat" is to squash the paper into the smallest, densest ball possible, and throw the resulting ball. Depending on the point of the contest, it may be advantageous to think about similar "cheats".

Finally, if you do need to control motors and suchlike, could you use something like Lego Mindstorms?

Hope this helps. You don't have much time, though; so think simple!--Robert Merkel 02:26, 3 February 2006 (UTC)

Make it with Knex! You can do anything with that stuff (if you have a ton of it lying around). I once made a model of a power track for work, and my Gr9 daughter is using it to model DNA. --Zeizmic 03:00, 3 February 2006 (UTC)

Seeing the title, I instantly thought of Lego, but Robert beat me to that. All that is left for me to do is refer you to my former employer. This stuff isn't cheap, though, but it's also quite cool, som depending which country you're from (click 'dealers'), you might ask if the school wants to buy some of this stuff (if it hasn't already). For some pics see here <a href="nowiki>http://www.lipperfamily.org/lego robots.htm">here</a> (how do I make a link to a url that has a space in it?). DirkvdM 11:28, 3 February 2006 (UTC)

How do I make a link to a URL that has a space in it? — Like [http://www.lipperfamily.org/lego%20robots.htm this]. GeeJo _{(t) (c)} • 16:05, 3 February 2006 (UTC)

Ah, yes, of course, I knew there was an escape sequence for it, but I forgot which (could have looked it up myself of course). Thanks. Made the link now (I had left behind quite a mess with the various attempts). DirkvdM 19:12, 3 February 2006 (UTC)

Cheating

Does Cheating exist in Medical Colleges?and if it does,what measures have been taken to prevent that?and also can any information or data be provided to prove that? -- 192.203.136.254 02:00, 3 February 2006 (UTC)

Cheating exists in any school environment. I'm guessing they use the same methods anyone else uses. Teacher in the room during exams and not allow pen bags (to avoid hidden notes) are two such options. Why wouldn't cheating exist in medical colleges? - Mgm|^(talk) 09:13, 3 February 2006 (UTC)

Except during practical surgery exams ? --DLL 17:27, 3 February 2006 (UTC)

Sure it exists, but the negative consequences are so far reaching (no career and a wasted education) that not many dare. Unethical conduct is punished very strongly. I knew a Mayor's son in dental school (in his home town) who swindled with the dental gold during his last year. He got caught. No more school, and never a dentist. Period. Even being the Mayor's son didn't help him. Unethical conduct in students is a red flag for even worse conduct when finished. Those types of docs are called "quacks." When caught they just become "holistic," "natural," and "alternative medicine" doctors, claiming that they are being persecuted. How convenient! (not) -- Fyslee 17:45, 3 February 2006 (UTC)

I know someone who told me of a friend of theirs who, in Medical school, cheated on their Ethics exam. Confusing Manifestation 13:44, 5 February 2006 (UTC)

Equation Balancing

I'm trying to a stoichiometry problem for my chemistry class right now, but I can't balance this equation, a single replacement reaction for aluminum and copper (II) Nitrate:

Al + Cu(NO3)2 = Cu + Al(NO3)3

Can someone please explain to me how to balance this out?

Before you think about balancing it, you have to figure out what the products are. —Keenan Pepper 02:28, 3 February 2006 (UTC)

Okay, got the products. Now how do I balance?

Consider one element at a time. Say you decide start with oxygen. There are 6 oxygen atoms on the left and 9 on the right. You must add coefficients so that the number of oxygens on either side is the least common multiple, 18. Continue with all the other elements until you arrive at a stable solution. —Keenan Pepper 03:47, 3 February 2006 (UTC)

Writing down the oxidation numbers is also helpful. Pilatus 03:33, 3 February 2006 (UTC)

Would it be 2Al + 3Cu(NO₃)₂ = 3Cu + 2Al(NO₃)₃?

I think coding the subscript was more difficult than balancing that. ;) Captain Jackson 05:44, 3 February 2006 (UTC)

Huh?

Why is there an Opera:blank in Opera (web browser) when there's a universal about:blank ? — Ilyanep (Talk) 02:41, 3 February 2006 (UTC)

Probably for the same reason there's an about:Mozilla in FireFox. Because they can. GeeJo _{(t) (c)} • 16:10, 3 February 2006 (UTC)

Something to add to Subject: Allergies

Hello, this is a new reader doing a report on Allergies and i could not find out anywhere on the internet where it shows specifically the different steps of what different allergens do in the body cell-wise... like an easy to follow step analysis to show how the cell is affected by allergens. thanks for taking the time to read this and i will hope to be able to learn and find out about these... i have tried to explain my subject quite thoroughly, and please excuse me if you do not understand it :P... --209.165.173.63 07:47, 3 February 2006 (UTC)

• It's a bit science-jargon heavy but our article Allergy has some info on that. I'm suspecting the first book listed in the references section can tell you things in more detail. Don't just really on the internet for you information. There's some great books out there. - Mgm|^(talk) 08:52, 3 February 2006 (UTC)

SIM card

how does a sim card works? i would also like to know about the internal structure of sim card.how it receives and sends data and what does the metallic grooves on the card mean? thank you —The preceding unsigned comment was added by 202.141.49.72 (talk • contribs) .

I would tell you to use the search box and look at SIM card, but that article doesn't give much information on how the card internally works. It explains a fair amount though. -- Daverocks (talk) 09:11, 3 February 2006 (UTC)

The GSM/UMTS SIM card interface will be specified on 3gpp.org. The summary, though, is that it's a small computer (with it's own ROM/Flash memory/RAM and Processor). I guess by "metallic grooves" you mean the contacts? The metal contacts on the surface provide power to the SIM and also act as a communications channel to and from the device the SIM is connected to (e.g. the phone).

Real life SIM cards will be small/thin integrated circuits with various protective layers around them. There are (were?) some good sites around with information about security of SIM cards. If you look for physical attacks, you will see information about the actual structure of the card. Mozzerati 22:05, 4 February 2006 (UTC)

Turtles

I have baby water turtles as pets and i was wondering how old do they have to be (in human years) for them to start mating?

• ~*~*~*~

I imagine this would depend on the particular species. But this site states that for painted turtles, the males start at 3 years and females at 6. - Akamad 11:31, 3 February 2006 (UTC)

Whoa, that's weird. I would have thought the males and females would start at the same age. Are there other animals whose ages are even more different? —Keenan Pepper 13:18, 3 February 2006 (UTC)

I believe humans have a bit of difference in timing between males and females. Puberty describes that somewhere, if you have time to wade through it. Black Carrot 05:21, 5 February 2006 (UTC)

Also, if you do get your turtles to mate, you might like to decide if you would like the babies to be males, females, or a few of each sex. This is determined by the temperature at which you incubate the eggs.

Clinical studies

A question I asked on Talk:Saccharin that has been as yet unanswered:

In the 'Saccharin and Cancer' section, it says that

"The notorious and influential studies of the kind published in 1977 have been criticized for the ridiculously high dosages of saccharin that were given to the test subject rats; dosages were commonly hundreds of times higher than "normal" ingestion expectations would be for a consumer."

This is, I believe, typical of drug studies, where actually buying 1,000,000 of the animal would be ridiculous, and so, a smaller number (10,000 typically?) is used, with far higher dosages than normal, and real-life population numbers are extrapolated from that. Am I correct here?

--Superiority 10:34, 3 February 2006 (UTC)

My understanding is that you are correct. The quote is basically the uninformed person's reaction to seeing the dosages that were used. I remember thinking the same thing when I first read how much they gave each rat, but before I'd studied such things. From my statistics classes in college, I recall that the modeling from huge doses given to rats or whatever to smaller doses for humans is considered a fairly reliable way to do the testing. It of course allows some possible errors, but they are believed to be understood well enough that the overall interpretation is valid. In other words, that quote should be removed from the article unless it could be attributed to a source. Then it would still require an explanation about how the research is done. - Taxman ^Talk 17:32, 3 February 2006 (UTC)

First note that the technique relates specifically to testing whether a substance is carcinogenic or not. We're not talking about "drug studies" as suggested above; megadoses of pretty much any drug are likely to be harmful.

The way I have seen it explained is, if a substance is not carcinogenic, then no matter how huge the dose is, the animal just won't get cancer (or more precisely, there will be the same number of cancers in the test group as would be expected without anything special going on). If it is a carcinogen, then increasing the dose will produce more cancers -- which means that a smaller (cheaper, faster) experiment will detect the carcinogenicity faster. It's like when someone makes a new connection in a gas main: the next thing they'll do (if feasible) will be to test it by putting in air at a pressure far above the normal gas pressure. Then if it's going to leak or fail, they'll find out at once, and if not, we can trust that it'll be safe for a long time at normal pressures.

The counter-argument to this is that this sort of carcinogencity test may be too sensitive. First, it can't be ruled out that some substances may be carcinogenic only in high concentrations. Second, if a substance causes cancer with very low probability at normal levels of use, this may not be a sufficient reason to ban it -- either it may have other benefits, or you may have the view that people should be free to choose their own risks. Of course this is a subject that can be debated at great length.

--Anonymous, 22:12 UTC, February 3, 2006.

Instant pancakes

I was wondering: if you heated up pancakes sufficiently, in an oxygen-free environment to keep them from combusting, would they melt? I ask because I had an idea for doing so, storing the liquid in an aerosol can, and marketing it as spray-on pancakes. --Superiority 10:38, 3 February 2006 (UTC)

An initial thought is that you are overlooking that much of the property of food is texture rather than purely chemical. Pancakes are light because they trap lots of air. They also have a variable texture because the outside is cooked more than the inside. Also, a large component is sugar: consider what you get back if you melt sugar then allow it to set. If you were to change state and reheat, what you got back would not be recognisable as a pancake. Now, spray on uncooked pancake batter: that sounds like an idea that could work, if you can overcome the stickiness, but it would still need cooking, rather than just heating. Notinasnaid 11:00, 3 February 2006 (UTC)

Curses! Foiled again! Darn you and your 'science', Notinasnaid, darn you all to heck! --Superiority 12:05, 3 February 2006 (UTC)

(I would still eat it)

Well, what do you expect from the science ref desk? I love the idea, though. I've come across some weird types of instant food, but spray-on pancakes really take the cake (if you don't mind the pun). :) DirkvdM 12:15, 3 February 2006 (UTC)

Speaking of puns, I doubt if these would sell like hot cakes, and even more if working out this idea would be a piece of cake. DirkvdM 12:16, 3 February 2006 (UTC)

Why would they melt? Well they won't anyway, they'll char. They'll turn into charcoal or something mostly consisting of it. --BluePlatypus 18:41, 3 February 2006 (UTC)

And even if whatever you heated up did melt, and you put it into a can, wouldn't it harden again when you brought it down to room temperature? So you'd just have a solid block of pancake with some metal wrapped around it. Black Carrot 05:16, 5 February 2006 (UTC)

Not necessarily, you might be able to pressurise it enough that it stays liquid, although that's still assuming that you could actually get them to melt in the first place. I still like the idea of spray-on pancake batter, though. Confusing Manifestation 13:42, 5 February 2006 (UTC)

Most powerful computer

What is the most powerful and advanced computer ever made?--XenoNeon (converse) 11:14, 3 February 2006 (UTC)

The supercomputer Bizznazz

After edit conflict:

The latest? The most advanced computer is by definition the latest. :) As for the most powerful, crappy computer magazines (not the one I read of course! :) ) regularly have a big headline FASTEST COMPUTER EVER or whatever. They could write such an article every week, but that would make the cheap trick a bit too obvious. Of course, this is about home computers. The most powerful computers are called (not surprisingly) supercomputers. And note that that article even has a section Current fastest supercomputer system. That, however, is about a single computer. One can also hook up loads of consumer computers to form a computer cluster (which usually run under Linux, I believe). I don't know which of the two has 'the biggest', but my bet is on the latter because there's basically no limit to it. If you stretch this a bit further, you can hook up a bunch of computers connected to the internet, such as is done with SETI@home (I participated in this for a while until I had to re-install msWindows again). If you could hook up all the computers on the Internet that would constitutequite a formmidable computer. Of course, this requires a very high level of distribution of the workload (what's the term for that again?), which is the biggest problem with parallel computing. With SETI this is fairly easy, but for other tasks it isn't (especially when the different results are inter-dependent and one program has to wait for another to finish). Now I realise that it is quite possible that some worm (or whatever) has spread over the entire Internet, using all computers in the world in such a clever way the owners don't notice. Maybe some hacker somewhere illegally has one humungous supercomputer at his disposal consisting of half the Internet or whatever, biting his lip because he can't tell anyone about it because he would immediately lose it. The good thing is that he has to work non-intrusively and thus non-destructively to keep this quiet. Unless of course he's waiting for that final big hit when he takes over all the world's communications and thus the world itself. Maybe a theme for the next James Bond movie. :) DirkvdM 12:04, 3 February 2006 (UTC)

The term David might be looking for is Embarrassingly parallel. It's very easy to get a whole set of loosely-connected computers to work on this type of problem together. The total computational efforts put in to solve some examples of these can far outweigh that of dedicated supercomputers. --Robert Merkel 00:33, 4 February 2006 (UTC)

The fastest computer would be the human brain, of course! After all, it does "compute", and it can do so at a high rate, with some scientists estimating that it can handle 20 quadrillion instructions per second. -- Daverocks (talk) 06:54, 4 February 2006 (UTC)

The Earth. – b_jonas 11:31, 4 February 2006 (UTC)

Don't forget the whole area of analog computers hybrid computers and workstation computers which, for some applications, blow away the digital computer approach, which I believe super computer falls into. However, the marketplace dictates what computers get sold, so some very high quality machines, like AS/400 for example, are far superior to stuff that most people buy, because most people want computers that are vulnerable to hackers, malware, computer insecurity problems. They would not be happy if they had a good system that never has any of that kind of problem. In my opinion, the most advanced computer is the quantum computer which was built several years ago in IBM labs. This is just a prototype, proof of concept, not yet ready for marketing, assuming there is a market for this. User:AlMac|^(talk) 23:52, 4 February 2006 (UTC)

history of chemistry

My question is: What was the branch of science called prior to chemistry?

Thank you

The search bar on the left-hand-side, near the top of every page is great: it allows you to find nearly anything you're looking for. If you type in Chemistry, there's a brief section in that article on the history of chemistry, as well as a link to the major article, History of chemistry. — Asbestos | Talk (RFC) 12:33, 3 February 2006 (UTC)

Bullet

If you point your gun to the sky and pull your trigger, will the bullet drop back down? The weather conditions are calm. Thanks -Betty

Yes, looking at the bullet article, it doesn't appear that it exceeds the escape velocity for Earth, and so it will fall back down to the ground. enochlau (talk) 12:39, 3 February 2006 (UTC)

Yes, as above, anyway, it's plain physics. Actually, hundreds of people are killed each year by "anonymous projectiles". gelo 12:45, 3 February 2006 (UTC)

Whoa, seriously? We should have an article about that. —Keenan Pepper 13:14, 3 February 2006 (UTC)

And falling bullets are deadly (or can be). It has been reported that in places where it is a cultural norm to fire rifles into the air, such as Iraq, people die on a daily basis from falling bullets. JackofOz 15:20, 3 February 2006 (UTC)

Hmm, I'd heard that that was an urban myth, and that the terminal velocity for a falling bullet wasn't enough to kill a person, but this site seems to prove me wrong. GeeJo _{(t) (c)} • 16:16, 3 February 2006 (UTC)

Really? I always thought that was true, but then I read a discussion (possibly on here) a while ago which concluded that the terminal velocity of a bullet wasn't enough to do any harm. Sum0 16:16, 3 February 2006 (UTC)

It is also important to differentiate those bullets fired exactly vertically and those simply randomly gired at a random high trajectory. These may hit someone a large distance away at a greater velocity than the terminal velocity of a vertical bullet. Rmhermen 16:42, 3 February 2006 (UTC)

Googling for "people killed by falling bullets" yields some interesting stuff. This blog says that people get killed by this practice in the USA, not just in Iraq, and mentions a study that was done on the subject. --Heron 17:44, 3 February 2006 (UTC)

It is also illegal in some jurisdictions. See Shannon's law for an example. Titoxd^{(?!? - help us)} 23:47, 3 February 2006 (UTC)

It's generally illegal to discharge a gun in a city anyway. But every year just before New Year's Eve, the Los Angeles police issue a warning about this. User:Zoe|^(talk) 03:11, 4 February 2006 (UTC)

I suggest updating Lebanese unload with the conclusions reached here. StuRat 02:40, 4 February 2006 (UTC)

This has already been discussed. See the [Reference_desk_archive/Science/January_2006#Firing_Distance science ref desk archive]. There (apart from a charming family tale), I calculated that the chances of a bullet shot in the air has a chance of 1/100.000 that it will hit someone. If that is true, then tens of million of bullets would have to be fired into the air to cause the death toll mentioned above. If they are all lethal. And it was also said that they aren't, so I'm inclined to think it is an urban myth. DirkvdM 10:59, 4 February 2006 (UTC)

I think it highly probably that tens of millions of bullets are fired into the air each year. With over 6 billion people on Earth, if only 1% of them fire a single bullet into the air each year, that would give us 60 million bullets shot in the air each year. I would bet the number is far higher. StuRat 18:54, 4 February 2006 (UTC)

By the way, note that the word 'terminal' in 'terminal velocity' is used here in the sense of 'in the end' not 'lethal'. :) DirkvdM 11:08, 4 February 2006 (UTC)

LPG

if LPG is odourless how do we know if there is a leakage??thanks,

59.92.35.61 12:25, 3 February 2006 (UTC)sidra59.92.35.61 12:25, 3 February 2006 (UTC)

LPG is mixed with ethyl mercaptain(C2H6S). If any leakag is there we get the smell of this. -Suraj vas

Suraj, if you type 4 tildes (~) after your posting, it will put your user name in automatically, and the date and time as well. Cheers JackofOz 07:34, 4 February 2006 (UTC)

It's spelled "ethyl mercaptan", also known as ethanethiol. —Keenan Pepper 13:16, 3 February 2006 (UTC)

In females

While having sex the penis erects in males. Then what happens in females?

It's all here. JackofOz 13:00, 3 February 2006 (UTC)

Shemales

Are there really any people having a brest and a penis?

Sure are. See hermaphrodite and shemale. JackofOz 12:56, 3 February 2006 (UTC)

A breast? I thought they usually came in pairs. :) DirkvdM 11:09, 4 February 2006 (UTC)

How about two penises then?   freshgavin TALK    08:45, 5 February 2006 (UTC)

Flu in winter

In school, we all learned that micro-organisms grow optimally when temperature is high (up to a certain point, when it becomes too hot). So why do flu and other epidemics always happen in winter ? -- Ze miguel 14:35, 3 February 2006 (UTC)

People are indoors more often during the winter, they are in close contact more often, and this promotes transmission from person to person. Another reason is that cold temperatures lead to drier air, which may dehydrate mucus, preventing the body from effectively expelling virus particles. The virus may also linger longer on exposed surfaces (doorknobs, countertops, etc.) in colder temperatures. Increased travel and visitation due to the holiday season may also play a role. Bizznazz

Not to mention that the pathogens spend very little time actually out in the cold - they spend most of their time in the comfortable 37 °C temperature of a human body. Finally, remember that a virus is different from a bacterium. They don't have a metabolism of their own and are fairly resistant to cold. GeeJo _{(t) (c)} • 16:22, 3 February 2006 (UTC)

Hey, our flu article has all this and more! --Zeizmic 21:38, 3 February 2006 (UTC)

WHAT IS THE SPECIFIC HEAT OF LINSEED OIL

What is the specific heat of linseed oil

There is no particular specific head of it - linseed oil is not a single compound. As such, it doesn't have fixed ratios of its constituents, and it may vary, and thus its specific heat varies as there will be different distribution of molecules. Elle _{vécut heureuse} ^{à jamais} (Be eudaimonic!) 22:29, 3 February 2006 (UTC)

A single compound can have very different specific heats depending on temperature. So it's a bit of a moot point because C_p is temperature-dependent, using a single value will always be at best an approximation. So as long as the ratio of constitutuents doesn't vary largely, it's not going to matter much. Googling for it, it's 0.44 Btu/lb*F at 60F. By comparison, most oils are around 0.40-0.47 so I doubt linseed oil is going to vary any more than that. --BluePlatypus 23:10, 4 February 2006 (UTC)

About .44 Btu/lb-°F @60 °F. see [2] --Duk 08:47, 5 February 2006 (UTC)

That is perhaps the ugliest unit I have ever seen used. Dmn € Դմն 16:29, 5 February 2006 (UTC)

Shooting a gun into water

If you fire a bullet into water, what happens? How far does it go before it slows to a harmless speed? Does it go at a different angle through the water than the air? —Keenan Pepper 22:35, 3 February 2006 (UTC)

This was recently featured on the television show Myth Busters. They found that slow small caliber bullets will travel a little ways into the water. The faster or larger the bullet, the faster it was torn into tiny, slow moving, harmless fragments. Also, they tried it from a steep angle because hitting the water at an angle would spread the impact on the bullet out over an extra microsecond or so. It didn't help the bullet survive impact with the surface of the water. Now - if you fire a gun under water - that is a different story. --Kainaw ^(talk) 23:11, 3 February 2006 (UTC)

or fire a gun with the barrel in the water... - Cybergoth 23:31, 3 February 2006 (UTC)

I'm not sure what happens to the bullet, but I know what can happen to the shooter.....;-) While on a reindeer hunt in the Godthåb fjord, Greenland, I was on my way back to camp after an unsuccessful day. I happened upon a small pond connected to the river. It was probably about 5x4 meters, and a half meter deep. It had about 8-10 nice fat trout in it, and I didn't have my fishing pole! Shucks. What to do..... Well, on one side of the little pond was a large boulder about seven feet tall. I climbed on top of it and looked over the situation from my great vantage point. I aimed directly down into the water at one of the fish and shot my cal. 30-06. I immediately was drenched in what amounted to a geyser of water. All the fish turned belly up for between 30 secs. and a minute, then recovered and swam out into the river. I didn't get a single one! -- Fyslee 23:41, 3 February 2006 (UTC)

Damn! You murder fishes and proudly boast about it! deeptrivia (talk) 05:14, 4 February 2006 (UTC)

But he (or she) didn't! He only attempted to! --Anon, 07:53 UTC

Not sure if that was meant in an ironic way, but this was fishing for food, which is a lot better than fishing for fun or breeding for food. The only argument against that that I can think of is vegetarian (it is wrong to kill whatever the excuse). If you eat meat (or, in casu, fish) then this is the animal-friendliest way to do it, provided you don't cause unnecessary pain for the animal (in which sense we do better than most other animals) because the animals get to live their lives in freedom. Actually, this sounds like a good way to fish - the fish get stunned by the blow. And if you're prepared for that (with a net) you'll be able to catch a lot of fish easily. This is sort of a mild version of fishing with bombs, which is way to destructive or poison (as done in Borneo, among other places), which also kills (not stuns) more fish than you need.

By the way, I'm amazed at the effect. I expected you to say you got a splash of water ricocheting straight back at you. But then there's a lot more energy than is needed to shoot back a squirt of water, so that has to go somewhere. Interresting story! DirkvdM 12:51, 4 February 2006 (UTC)

I thought that if you fired a gun into water while the end of the barrel was submerged, the chamber would explode in your face. Is this true? Cybergoth 16:48, 4 February 2006 (UTC)

The US Navy has reportedly developed supercavitating bullets, intending they be fired from helicopters to destroy mines, or from Phalanx/Goalkeeper like systems fitted to the sea hull of a submarine, intended to destroy incoming torpedoes. link from Google cache. -- Finlay McWalter | Talk 18:05, 4 February 2006 (UTC)

Fishing with firearms is legal in several places in the U.S. See [3] which mentions Vermont, Virginia and previously New York. So it must work. Bow and arrow fishing is more popular though. Rmhermen 19:11, 4 February 2006 (UTC)

The Frogman article has some interesting links to underwater firearms - basically using very very long bullets: APS underwater rifle, SPP-1 Underwater Pistol. Ojw 17:21, 5 February 2006 (UTC)

February 4

the size of a disk & multispectral images

please i would like to know how much disk space a 5000 × 5000 × 16 bit image require. thanks

Assuming that means 16 bits per pixel, and 5000 pixels in height and width, then if the image is a bitmap image, simple arithmetic comes out to 400,000,000 bits. At 8 bits per byte, that's 50,000,000 bytes, so roughly 50 megabytes. Of course a megabyte isn't really one million bytes, it's 1,048,576, so more arithmetic is needed. The size of a disk cluster might come into play as well.

Of course, if the image is being stored as a JPEG or with some other encoding method, then it's hard to determine the actual file size, since it is dependent on the properties of the image being stored. LarryMac 17:00, 1 February 2006 (UTC)

16-bit per pixel is uncommon in images - it's likely 16-bit per channel, which works out to 150 million bytes, or 143.0511474609375 megabytes. But as you said, compression will decrease that value. --Pidgeot (t) (c) (e) 18:58, 1 February 2006 (UTC)

The size of a disk? $\pi r^{2}$ - Sorry, coudn't resist --GraemeL ^(talk) 19:02, 1 February 2006 (UTC)

Considering raw image

Pixel in total: 5000 x 5000 pixels = 25 000 000 pixels

color depth: 16 = 2 x 8 bits/pixel = 2 bytes/pixel

total filesize: 25 000 000 bytes * 2 bytes/pixel = 50 000 000 = approx. 47.68 MB

Note that the W x H x B notation usually has B as overall bit-depth, not bits/channel. Using 16 bits/channel you'd have three times the value I just gave you. ☢ Ҡieff⌇↯ 19:44, 1 February 2006 (UTC)

That's pretty big. A standard digital photo is about 5 megapixel at 24 bits (8 bits per colour channel, of which there are 3). That's 15 MB, which is usually slightly compressed (meaning with barely visible artefacts) to about 2 MB. You're talking about 25 megapixel at (probably) 16 bits per channel. Uncompressed that would be 75 MB. Are you sure you need it to be that big? Generally, it's better to decrease the file size with compression than with a lower image size (pixel count). But an image size of 25 megapixel seems a bit over the top unless you want to do some very special stuff. What is it for? Especially a bitdepth of 16 bits per channel is way over the top. Even Photoshop can't handle that for a lot of operations because it's unnecessarily precise. DirkvdM 13:17, 2

February 2006 (UTC)

user posted a detailed question over an old question as a new section, so I'm moving the whole thing down to keep it active and avoid two sections over the same topic ☢ Ҡieff⌇↯

thanks for your help about the disk size requirement for a 5000 * 5000 *16 bit image. however i am concerned about finding out how much a multispectral set of 7 identical image require?

Well, since we're assuming raw images, just multiply our figures to 7. That is 47.68 MB * 7 = 333.76 MB ☢ Ҡieff⌇↯ 02:02, 4 February 2006 (UTC)

What creatures have hearts?

Which creatures or animals have a heart? I was expecting to find this information in the first paragraph of the heart article, but I haven't been able to find it anywhere. I'd be interested in both a generality (something like "all vertebrates and a few invertebrates" or whatever's accurate) for the first paragraph, and any more detailed information that could be put later in the article. Thanks! -- Creidieki 01:07, 4 February 2006 (UTC)

I think all animals more complex than cnidarians have hearts or analogous organs. ‣ᓛᖁᑐ 01:18, 4 February 2006 (UTC)

Also note that some animals, such as worms, have multiple hearts. StuRat 02:27, 4 February 2006 (UTC)

As does Dr Who, by the way. DirkvdM 12:54, 4 February 2006 (UTC)

Let me use an indirect approach. This site says "The heart develops in a human embryo around day 23." Since the development of the embryo mirrors the evolution, you only need to know which point of evolution is represented by day 23. I don't know when that is, but it must be fairly early in evolution. Any animals that evolved in our line after that moment will also have hearts (unless it evolved out in some line, which sounds rather unlikely). Assuming the heart developed only once on Earth (which is a rather big assumption), animals in other lines of evolutio will not have a heart. DirkvdM 13:06, 4 February 2006 (UTC)

Aren't you assuming that ontogeny recapitulates phylogeny? —Keenan Pepper 13:39, 4 February 2006 (UTC)

I am, although I didn't know what it was called or that it was named after this phrase. So I wasn't referring to Haeckel. But I was referring to the modern accepted idea that (quote from the article - quite an interresting little read with nice examples) "Generally, if a structure pre-dates another structure in evolutionary terms, then it also appears earlier than the other in the embryo." So my reasoning stands (and I am strengthened in my belief, thank you for that :) ). DirkvdM 10:48, 5 February 2006 (UTC)

Sea life

Do any echinoderms or nudibranches have hearts? ‣ᓛᖁᑐ 01:39, 4 February 2006 (UTC)

"Echinoderms...have no heart, brain, nor eyes" (source). Some (all?) nudibranches do: Neurotransmitter regulation of the heart in the nudibranch Archidoris montereyensis. Hope that helps, --Lox (t,c) 21:03, 4 February 2006 (UTC)

Holograms

Hello, we are trying to find out exactly how monochromatic, transmission holograms work. Your article says "diffraction from the fringe pattern on the film reconstructs the original object beam in both intensity and phase". Exactly how is the virtual image recorded and reproduced so that it appears 3D?— Preceding unsigned comment added by 203.32.123.14 (talk • contribs)

I'll try to explain it as I best understand it from the book Shufflebrain by Paul Pietsch (who, awesomely, has excerpts from this 30 year old book online! [4])

Light waves are transformed by their incidence on an object, in phase and wavelength. This transform is transformed back by the effects of the lens and retina of the eye, resulting in a limited (2-D) perception of the original object. Light is similarly transformed when contacting regular photographic film, resulting in the storage of a limited amount of information on the object in an image. Think of these transforms as cancelling out, in a manner of speaking.

In holography, the transformed light is transformed again by interference with a reference wave, resulting in the transform itself being stored (in a diffraction grating) in the photographic medium, rather than the transform of the transform. When this transform is reconstructed by the reference wave, we get the same effect as when the light was initially incident on the object, or what appears to actually be the object.

Does that help at all? KWH 04:37, 4 February 2006 (UTC)

That makes a little bit more sense, but exactly how is the transform stored in the plate?

Over the years, I've read a lot about holograms, but I've never truly understood them. There are no really simple explanations. Now, however, you can buy special kits and make your own! This might be the best way to understand. --Zeizmic 12:29, 4 February 2006 (UTC)

Of course, it's quite possible to use a thing and even build it without understanding all the details. For example, how many people who work on or own a car really understand the physics needed to explain combustion at the subatomic level ? StuRat 19:27, 4 February 2006 (UTC)

Point taken, thanks for the help

Polyploidy

Could anyone explain in simple terms the difference between autopolyploidy and allopolyploidy? Zafiroblue05 04:23, 4 February 2006 (UTC)

autopolyploids resulting from one species doubling its chromosome number to become tetraploid.

allopolyploids resulting from two different species interbreeding and combining their chromosomes.

I cut and paste straight from the polyploid article. Is that not plain language? David D. (Talk) 05:34, 4 February 2006 (UTC)

• Fair enough. I guess my question really is - what does it mean that autopolyploids "exhibit multisomic inheritance, and are often the result of intraspecific hybridization" and that allopolyploids "exhibit disomic inheritance (much like a diploid), and are often a result of interspecific hybridization"? (In particular, the hybridization thing I don't understand.) Also cut and paste straight from the polyploid article. Zafiroblue05 21:10, 4 February 2006 (UTC)

Multisomic means that more than two chromosomes pair (sometimes called multivalent). Since the genome has doubled there are now four chromosmes and they can all pair together. This makes segregation of alleles less predicatable.

If the diploid has two chromosome pairs: AA and BB When it is autotetraploid it will be AAAA and BBBB. Thus four chromosomes together are multisomic.

Disomic means that only two chromosomes pair, the same as normal. Why the difference. Since alloploids are the result of two different plants hydridizing together (interspecific) the equivalent chromosomes are not identical and therefore cannot misspair with each other.

If the two diploids have two chromosome pairs each : AA and BB (species 1) and CC and DD (species 2). When it is allopolyploid it will be AA, BB, CC and DD. Thus four disomic chromosomes are characterictic of a allopolyploid. (the diploid in each case has two disomic chromosome pairs).

Hydridisation just means that species A mates with species B. What makes this special though is that it is only fertile if there is a duplication of the genome. if not the plant would be sterile. So two events are required to get an allotetraploid.

1) Interspecific hydridisation (AA BB cross to CC DD) to give A B C D (this is sterile since the chromosmes are not equivalent cannot pair and therefore cannot segregate correctly during meiosis).

2) Genome duplication of A B C D to give AA BB CC DD. This plant is now allotetraploid and fertile since all four chromosme pairs can segregate.

David D. (Talk) 23:45, 4 February 2006 (UTC)

How many species?

Approximately how many species of organisms, eukaryotes and animals are thought to be alive? Common Man 06:40, 4 February 2006 (UTC)

Would it improve my chances for a reply if I wrote that I'm 15 years old and I'm looking for friends among eukaryotes, too? Or is the Science reference desk just not the right place to ask such questions? Common Man 20:00, 4 February 2006 (UTC)

Here's an answer to your question [5]: It says "About 1.4 million species of eukaryotes have been described so far."

Note that this is the number described, not the actual number of species (which is unknown). There are surely many more that we haven't described yet out there. About animals, keep in mind that these are a subset of eukaryotes. BTW, there is an interesting website called Tree of Life. Hope that helps! --Uthbrian (talk) 20:33, 4 February 2006 (UTC)

Thank you! And thanks for the link to Tree of Life - what a great project! Common Man 21:42, 4 February 2006 (UTC)

Good luck finding friends among the eukaryotes!   freshgavin TALK    22:22, 4 February 2006 (UTC)

Friends

How can i find online friends( I am 15 years old)?

You could start by figuring out the things you're interested in and searching for internet forums related to those. --Robert Merkel 08:06, 4 February 2006 (UTC)

MySpace is a good bet, where you can search by various categories. You could also try LiveJournal. Sum0 12:56, 4 February 2006 (UTC)

MySpace is owned by big bad wolf Rupert Murdoch, so I'd give that one a wide berth (hell even Microsoft isn't as evil as Fox).

LiveJournal, on the other hand, runs on open source software. This, however, does not mean that the contents (the users' postings) are open source (as they are on Wikipedia), so I'm not sure about that. But at least it sounds better. DirkvdM 13:24, 4 February 2006 (UTC)

There are also online game sites, like Pogo [6] , where you can play games and chat at the same time. This allows an easy start to any conversation, where you can start by talking about the game. These sites are often free (although they do charge for "premium" services and games). Be careful to avoid gambling sites, which call themselves "gaming sites", much like prostitutes refer to their "services" as a "date". StuRat 19:15, 4 February 2006 (UTC)

• OKCupid is good for finding special friends. Night Gyr 20:34, 4 February 2006 (UTC)

waves

Supposing a stone is thrown into a pond of water,there is a leaf floating on the surface of the water,wont the ripples created by the stone disturb the motion of the leaf??If so,what happens during this?

thanks

Well, that'd probably create ripples. The leaf will move on an elliptical tragetory, but won't really change position. See the little diagram on wave. ☢ Ҡieff⌇↯ 09:52, 4 February 2006 (UTC)

The wave won't displace it permanently (only up and down as long as the ripple lasts in that spot). But there will also be some permanent water displacement (better known as a 'splash') and if the leaf is close enough to the rock it'll get knocked out of position by that. This is often forgotten. I imagine someone once came with this clever reply and since then everyone has been copying it without checking against reality. Something like the standard answer to the question whether you will remain drier if you run in the rain, namely that the rain will hit you at an angle, making you wetter at the front, where the surface is larger, so you will get wetter. Clever answer. Except that it is a load of bull. The angle the rain makes relative to your body is exactly (?) the same angle your body makes to the ground in order not to fall over. So the rain still hits you from 'straight above' (on the head, I mean). That is, if you regard the body as a stick on a wheel. Which it isn't. The movements of the human body are much more complicated. Th only way to find out is to try. And from my experience I'd say RUN! DirkvdM 13:34, 4 February 2006 (UTC)

Regarding the rain thing, there's a reasonably easy way to show that running is indeed optimal. Assuming the rain is falling straight down, no rain will hit you from the front unless you move. But you do need to move to get anywhere, and, since the density of raindrops in the air is more or less constant, the total amount of rain hitting you from the front is in fact directly proportional to the distance you move, regardless of speed. Meanwhile, the amount of rain falling on your head from above is directly proportional to the time spent in the rain. Since the total amount of rain hitting you is the sum of these two contributions, minimizing it means choosing the shortest path and moving along it as fast as possible. In other words, run straight for cover.

The above analysis assumes that your body remains vertical regardless of speed, but, as you've noted earlier, leaning forward while running actually helps you stay dry, at least as long as you don't lean so far that your back gets wet. A more significant assumption is that the rain falls straight down. If it doesn't, the situation gets more complex. Essentially, if the raindrops are moving fast enough in the direction you're going, it may be be better to match your speed to the horizontal velocity of the rain. The cutoff point depends on the ratio of the horizontal and vertical cross sections of your body. —Ilmari Karonen (talk) 20:54, 4 February 2006 (UTC)

Cecil Adams had a go at that a while ago: http://www.straightdope.com/classics/a3_395.html I have to say, though, all the explanations I've seen of it seem horrifically simplistic and very difficult to apply usefully. I've gotten fairly good at not getting anything important wet while moving through rain, under a fair variety of conditions, and here's what I've learned: If it's light, it doesn't matter how fast you go. If it's medium, hunch up, hug your books to your chest, and move fast, but not fast enough you slip. If it's hard, you're screwed anyway and might as well enjoy it. Or carry an umbrella. Black Carrot 05:03, 5 February 2006 (UTC)

I like the last one. Could one term that 'positive fatalism'? Googling that even gives some results. DirkvdM 10:54, 5 February 2006 (UTC)

sound

how does the whispering gallery of st.paul's cathedral(London) reflect sounds?59.92.55.130 10:12, 4 February 2006 (UTC)amy59.92.55.130 10:12, 4 February 2006 (UTC)

See whispering gallery. --Heron 10:25, 4 February 2006 (UTC)

File renaming script

I have a bunch of text files (html) of which I want the name and first line reversed. The files ar all named NRC-xxxxxxx-yyyyyyyy_body.html, where the 8 x's are the date and the 8 y's the article (they're newspaper articles). I want this to appear at the top of the list (added to the text, not replacing anything), and I want the original first line (the title) to replace the name, with the spaces replaced by underscores (leaving the .html intact of course and possibly leaving the date in there too). This way it's easier to categorise the articles by subject, whilst leaving the date info (and the original name on the original site) available. The number of files is rather large and about 10 are added to it everyday, so its rather important I automate this. So thanks for any help. DirkvdM 14:30, 4 February 2006 (UTC)

Adition: in the source, the whole article is formatted in a table, so I want the original filename (the date) to appear between the <body> and <table tags (where closing bracket of the table tag comes much later). And the title (which should go in the filename) appears like this:

 <td class="artheader">...title...</td> 

Also, looking at the source, I notice that at the end of the file there is the following bit:

<noscript><img src="...URL..." width="1" height="1"></noscript> 

where I've replaced the original text with URL, which I also want to appear (visible) at the top of the page. DirkvdM 14:55, 4 February 2006 (UTC)

I had to do this in UNIX a long time ago, and it wasn't easy. I first built a script to construct a series of rename operations written to a file, using the "ls", "cut", and "grep" commands, to get something like this:

mv OLDFILENAME1 NEWFILENAME1
mv OLDFILENAME2 NEWFILENAME2
mv OLDFILENAME3 NEWFILENAME3

Then I executed the script. I had to do it this way to avoid a recursive error, where the new names would be renamed again, and so on, forever. StuRat 19:05, 4 February 2006 (UTC)

This is why I have mIRC around. It's so pathetically cheap to program on that these stuff can be done within the minute. ☢ Ҡieff⌇↯ 19:22, 4 February 2006 (UTC)

mIRC is msWindows-only and only valid for 30 days (after which I have no way to pay for it even if I wanted to), but I'll give it a try. I should really learn how to write scripts, but then there are too many things I should do which get preference (so why am I 'wasting' time here :) ). I was sort of hoping someone would say "Oh, that's easy, I'll take 5 minutes to write this for you". Well, there was the off chance. Thanks anyway. DirkvdM 13:41, 5 February 2006 (UTC)

Modern Physics: Radiation of Blackbody

My professors are busy. I am doing an exercise about Modern Physics. If anyone can help me to check, I’d be happy. Thank you first.

Q:Please derive all of Rayleigh-Jeans’s Black Body Radiation Theory. And tell out why they failed.

My solution is a little few. ‘Cause in Taiwain, any testing time has its own limit. I do it as brief as I can. As the followings:

In a cavity,there exists some EM-waves to travel all-in it.

• (1)EM-waves' frequency $\nu \rightarrow \nu +d\nu$,

With $N(\nu )d\nu ={\frac {8{\pi }V\nu ^{2}d\nu }{c^{3}}}....................(1)$

which gives that the more frequency(as${\mathcal {\nu }}$),the more State-Numbers(as N). In the formula,${\mathcal {V}}$ is as Volume.

Considering one dimensional standing-wave $\Longrightarrow {\sqrt {n_{x}^{2}+n_{y}^{2}+n_{z}^{2}}}={\frac {2a}{\lambda }}={\frac {2a\nu }{c}}$

It can be set ${\mathcal {,}}r,$ be a ${\frac {1}{8}}$ shell's radius.

Because EM-waves have 2 modes,

${\mathcal {,}}N(r)dr=2N'(r)dr=2\cdot {1 \over 8}\cdot 4{\pi }{r^{2}}dr,$

Where ${\mathcal {,}}r,$ is a state-number which keeps a constant : $r={\sqrt {n_{x}^{2}+n_{y}^{2}+n_{z}^{2}}}$

And ${\mathcal {,}}n_{x},n_{y},n_{z},$ can have different combinations to each other.(${\mathcal {,}}4\pi r^{2}dr,$ is for a shell volume of whole-circle speed.)

By $2\times {\frac {1}{8}}\times 4{\pi }r^{2}dr$, gives ${\mathcal {\pi }}r^{2}dr$

• (2)With "Energy continued distrubution of S.H.O." and with Boltzmann speed distribution, so energy released by a vibrating frequency ${\mathcal {\nu }}$ on atoms ${\bar {\epsilon }}(\nu )=\epsilon (\nu )=kT$

By the difinition of energy density:

$\rho (\nu )d\nu ={\frac {u(\nu )d\nu }{V}}$

Total energy is that average energy multiplies state-numbers

${\frac {{\bar {\epsilon }}(\nu )\cdot N(\nu )d\nu }{V}}={\frac {N(\nu )\cdot kTd\nu }{V}}....................(2)$

• (3)In a cavity, the energy density of $\nu \rightarrow \nu +d\nu$

With${\mathcal {(}}1)and(2)\Longrightarrow \rho (\nu )d\nu ={\frac {8\pi \nu ^{2}}{c^{3}}}kTd\nu$. Which we can ignore ${\mathcal {,}}d{\nu },$both sides of it.

Obviously, as $\nu \rightarrow \infty$ then the energy becomes $\infty$,any blackbody are broken, it is impossible! (Tragedy of UV-light) So their theory was wrong when higher frequencies.--HydrogenSu 17:07, 4 February 2006 (UTC)

It's called the ultraviolet catastrophe. —Keenan Pepper 17:12, 5 February 2006 (UTC)

A free software for surveys

Hello. I am looking for a free software that would allow one to carry out a survey from the building of the questionnaire to the exploitation of the results stored in the database. Can anyone help me find this? I am not speaking about online polls commonly used by webmasters. Thierry Caro 17:38, 4 February 2006 (UTC)

Gunpowder & creation of explosives

I've been told gunpowder is not a true explosive, as it really just burns very rapidly. If that's the case, if gunpowder was never discovered, how would this have influenced the creation of other, true explosives? Would it have put it back significantly? --Impaciente 18:58, 4 February 2006 (UTC)

I don't see the distinction, an explosion is just a rapid burning (oxidation). StuRat 19:14, 4 February 2006 (UTC)

Gunpowder is considered a low explosive, because as you said, it merely burns rapidly (see deflagration). The chemical reaction only proceeds with the flame front, i.e. the ignition of the material. Contrast this with detonation, where the chemical reaction can proceeds with the shockwave (which is faster than the flame front)-- see explosive material for more info.

About the historical importance of gunpowder, I'm not sure what would've happened if gunpowder hadn't been discovered. The outcomes of wars would almost surely have been affected, so I think it would be hard to guess what might've happened with regard to the development of explosives. --Uthbrian (talk) 20:12, 4 February 2006 (UTC)

I think you're talking about the distinction between low-explosive and high-explosive. This is explained pretty well at explosive material. Now, to the subjunctive question of what would happen if gunpowder was never discovered (i.e. the compound did not exist).

According to dynamite, Nobel invented his "Safety Blasting Powder" as a safer alternative to gunpowder and nitroglycerin. According to nitrocellulose, the discovery of guncotton was serendipitous; it was discovered by accident. The likelihood is that mankind would somehow have arrived at dynamite and later high-explosive compounds, and they would probably be the same ones we see today.

The question of how it would be put back is immensely complex. You must consider all the political effects (positive and negative) over hundreds of years if gunpowder did not exist in certain wars. We also might be living in a world without a Nobel prize. However, it might be said that the discovery of gunpowder was not a surprise, but was inevitable as cultures sought to find a more effective way to inflict death on others. Therefore, if gunpowder were not discoverable, nitroglycerin and dynamite might have been discovered earlier, and would be more effective, leading perhaps to Mongol or Arab domination of Europe.

Or, perhaps the person who discovered it would just accidentally blow themselves up. Hypothetical questions are difficult when you're dealing with hundreds of years of history. KWH 20:27, 4 February 2006 (UTC)

Some background: An explosion is a delayed expansion compressed in time. If oxidation (or whatever) leads to a (rapid) expansion and you hamper the expansion you'll get an explosion when the barrier is broken. If the barrier is too low (not strong enough wrapping around your home-made explosive - I speak from experience) you'll get a 'poof' or even just a 'sizzle'. I haven't managed to make one with too strong a barrier, though. Wonder what would happen. I suppose the expansion would kill itself, leaving an incomplete burning of the 'explosive'. For readers who need a disclaimer for lack of brainpower: don't try this at home. For others: feel free to try this, but do use the brainpower you (think you) have. DirkvdM 11:04, 5 February 2006 (UTC)

Disease Spread in Enclosed Area

If you have a given number of people in an enclosed area for a given period of time, such as a hospital or stadium, and some are infected with a contagious disease, how do you figure out how many more people the disease spreads to? 70.248.231.20 19:54, 4 February 2006 (UTC)

Unm...I just afford this:in Taiwan,people's influence just limit in "cold"(感冒) . In Japam,envirnment is better than in Taiwan,but I don't know very much about Japan. AIDS is not Asians' influence. Main is 肺炎 or SARS.--HydrogenSu 20:02, 4 February 2006 (UTC)

It's difficult to say. There are many variables involved, and in fact, epidemiologists have developed various mathematical models to investigate this phenomena. See Mathematical modelling in epidemiology for more info. Note that there are many assumptions involved in modelling, so these models don't fully represent the actual transmission of disease. --Uthbrian (talk) 20:15, 4 February 2006 (UTC)

Rape in the animal kingdom?

Does it exist? 83.5.189.10 20:05, 4 February 2006 (UTC)

Yes, it does. Can't name any particular species, but I'd guess it's common on species where the male is dominant over the female. ☢ Ҡieff⌇↯ 20:22, 4 February 2006 (UTC)

Ya, I remember seeing some show on Discovery channel about spiders. The male would sneak up on the female and hold her with his front legs. He would then use his pedipalps (I think that's what they're called) to kind of scoop his sperm into the female. Then the male had to run quickly away, so as not to be eaten by the female. --Dimblethum 20:30, 4 February 2006 (UTC)

No, it doesn't. One of the basic elements of rape is knowledge that the raped person is not consenting (or recklessness as to whether he/she is consenting). There is no evidence that any animal other than homo sapiens can understand the concept of consent. Mark^{your words} 20:36, 4 February 2006 (UTC)

I would think running away, biting the suitor, etc., is a pretty good indication that consent is not given. StuRat 00:27, 5 February 2006 (UTC)

Oh really! deeptrivia (talk) 21:28, 4 February 2006 (UTC)

It's not really clear that that's rape though, it's kind of a human social construct. Not, of course, to take away from how serious it is, but it's still a construct.

Rape is a human social construct- that's exactly the point. Asking whether bulls rape cows is as nonsensical as asking whether boy cabbages rape girl cabbages. Mark^{your words} 20:53, 4 February 2006 (UTC)

Note: The above comment is factually incorrect (and even offensive). deeptrivia (talk) 21:25, 4 February 2006 (UTC)

PS: See Sociobiological theories of rape. deeptrivia (talk) 21:27, 4 February 2006 (UTC)

Certainly not the former; if the latter exists in your mind, that's your problem. Mark^{your words} 21:59, 4 February 2006 (UTC)

I'm not sure "rape" is a particularly good word for it, but male dolphins will "herd" females, following and surrounding them, and forcing them to mate. This herding can last from minutes to months. Also, dolphins tend to be given other behavior that could be termed lecherous [7] Raul654 20:48, 4 February 2006 (UTC)

But hey, nobody talked with the female dolphins, so they must be enjoying it for all we know! ... Now, honestly, this get filed as rape in my book. Also, to quote Mark, "There is no evidence that any animal other than homo sapiens can understand the concept of consent." Oh really? What the hell are mating rituals then, when the female doesn't let a "unworthy" male to mate? That's consent, isn't it? And if the male uses force to copulate with her anyway, wouldn't it be rape? ☢ Ҡieff⌇↯ 21:48, 4 February 2006 (UTC)

No no no. A male spider has no concept of a female spider existing as a conscious entity. This is ludicrous anthropomorphism. Mark^{your words} 21:59, 4 February 2006 (UTC)

Anthropomorphism anyone? Rape is a social construct, it isn't simply sexual relations without consent. The concept of consent is a human one, and laws, rules and human norms of rape vary by place and time. Animal social constructs are likewise different, if they exist at all.

There are clearly cases when the female refuses any attempt from certain males to copulate. If you say there's no consent in there, then you're being a bit speciesist. Now, if by "rape" the questioner asked about all this social aspect, with norms and etc, then there's no evidence of such thing as rape in the animal kingdom. But if "rape" is just unconsensual (sp?), forced sex, then there's no reason to think there isn't. ☢ Ҡieff⌇↯ 22:12, 4 February 2006 (UTC)

It's not remotely 'speciesist'. If there were a Mr Spider which had the intellectual capacity to understand that Miss Spider was a) a conscious organism and b) one which didn't want to be shagged, then he would be capable of rape regardless of his species. But there isn't. Spiders, blue whales and broccoli are all equally incapable of rape, murder or love. Mark^{your words} 22:26, 4 February 2006 (UTC)

But we know that "Ms. Spider" chooses a male she wishes to have sex with based on several things. If the male, even being rejected, forcefully has sex with the female anyway, that'd be rape. ☢ Ҡieff⌇↯ 22:34, 4 February 2006 (UTC)

I'm not sure on what basis you would call it that. Which definition of rape would you use? One of the hundreds of legal definitions? One of the thousands of social constructs? How would you demonstrate that there was any analagous understanding of that in spiders? 67.40.249.122 22:41, 4 February 2006 (UTC)

Firstly, Miss (she is known to be unmarried) Spider does not 'choose' in the sense of conscious human choice- she responds to stimuli. Secondly, rape (in every human society of which I know) involves a mental element (mens rea) in addition to the physical element (actus reus). Mr S is incapable of that mental element. Mark^{your words} 22:48, 4 February 2006 (UTC)

Well, spiders are a lot different than, say chimps, lions or other mammals. This whole spider thing is a bit pointless. I don't really believe arachnids or insects have any form of "will", but lots of other animals do, and this was my initial point. This spider thing carried away the argument to a unproductive area. ☢ Ҡieff⌇↯ 23:05, 4 February 2006 (UTC)

Well, I don't think I would say that there is no such thing as forced sex in the animal kingdom, but the problem is applying the human social construct of rape to that.

Indeed, but considering the depth of the questions on the first place, I think you're assuming a bit too much. (Also, please sign all instances of your messages, even on different parts of the same discussion) ☢ Ҡieff⌇↯ 22:34, 4 February 2006 (UTC)

Sorry - not sure what you mean - what am I assuming? Do you mean that I am assuming that there is no animal construct that is analagous? 67.40.249.122 22:38, 4 February 2006 (UTC)

Rape happens when "the victim is forced into sexual activity, in particular sexual penetration, against his or her will." This can apply in the context of most higher animals (not restricted to mammals). The West does (finally) understand life much better today compared to Biblical times, and no one that matters equates cows and bulls to cabbages any more. deeptrivia (talk) 23:00, 4 February 2006 (UTC)

Where did you get that definition? It doesn't matter, it's as good as any other, but the choice to use it is a cultural choice - you would choose differently if you were a rural afghan, or a medieval cleric, or, indeed, a member of the religious right. Your taking a definition that has current legitimacy within your cultural context, and applying it, not only to all people, cultures and times, but species as well? I think that's a stretch too far. 67.40.249.122 23:04, 4 February 2006 (UTC)

Not really, no. "Forced into sexual activity against his or her will" is pretty straightfoward. If you assume the creature in question has any form of will, then that definiton of "rape" is applicable. Also, by your logic, rape doesn't really apply in any case because some cultures find it acceptable? ☢ Ҡieff⌇↯ 23:10, 4 February 2006 (UTC)

That's your definition. Not all cultures / times have or do agree with you. I'm not going to argue that you're wrong, just that there is not only one definition. For example, whether someone can rape their wife is a question that I suspect that I know your reply to, but different laws and cultures give different answers. I know for a fact that spiders don't have the same concept of marriage as people, so what do we do with that? It just doesn't apply to animals. There may well be something else, but it's not the same thing as rape in humans, even if we could ever agree on exactly what rape in humans is. 67.40.249.122 23:18, 4 February 2006 (UTC)]

So, you're basically saying animals don't choose, they don't have preferences or don't have any will? ☢ Ҡieff⌇↯ 23:48, 4 February 2006 (UTC)

I think they appear to make choices, and have preferences, I assume they have will, but all of those are suppositions on my part, I can't prove it, and all are irrelevant to the question of whether they have a cultural concept equivalent to rape. It's quite possible that an animal may be forced to have sex against their will, it doesn't make it rape. One animal may kill another, it doesn't mean they consider it murder, one may force another into extinction, it probably isn't genocide. 67.40.249.122 00:10, 5 February 2006 (UTC)

Cats always sound to me as if they're being raped. That awful noise they make hardly seems to be a response to pleasure. (I guess that's where the word "caterwauling" comes from.) JackofOz 23:15, 4 February 2006 (UTC)

That last comment turns out to be true. Caterwaul is from Middle English caterwawen, "to cry as a cat," either from Medieval Dutch kater, "tomcat" + Dutch wauwelen, "to tattle," or for catawail, from cat-wail, "to wail like a cat.". Well, there you go. JackofOz 23:54, 4 February 2006 (UTC)

Why do cats cry when having sex? Consider this - the cat's penis has spines on it. Sex is painful for cats. Grutness...wha? 00:09, 5 February 2006 (UTC)

You're right - sex just isn't the same thing for cats as it is for people. The concept of rape predisposes a whole load of values that we just have no idea whether animals have. It could well be (and I speculate here) that no female cat ever wants to have sex. That sort of biology, along with very different social norms, would make it hard for cats to have the same view of sex, or rape, as people. 67.40.249.122 00:33, 5 February 2006 (UTC)

Many animals are monogamous. I don't see any cultural relativism in this definition..it's a pretty simple one. deeptrivia (talk) 23:56, 4 February 2006 (UTC)

It's a simplistic one. Rape, to the extent that it matters, is all in the minds of the rapist and the victim. Other animals just don't have the right kind of minds. Mark^{your words} 00:41, 5 February 2006 (UTC)

The fact that some animals display a behavioral trait doesn't allow us to deduce anything about their values, if indeed they have values. The fact that a creature is monogamous doesn't tell us anything about their cultural concept of rape, if any. 67.40.249.122 00:07, 5 February 2006 (UTC)

This is very mysterious. What was Mother Nature thinking when she made the very thing that is essential for the survival of the species so painful (and presumably, from the female cat's perspective, undesirable)? What purpose does painful sex serve? If it isn't pleasure that guarantees the continuation of the species, what is it? Cats are known for their ability to fight to get away from unwanted attention, so why do the females submit to this? Or is the tom stronger and more powerful, meaning he gets his way? Is sexual pleasure a human concept that doesn't necessarily apply in the rest of the animal kingdom? JackofOz 01:29, 5 February 2006 (UTC)

Female cats don't have menstrual periods, so the injury from the spike is used to signal their bodies to release eggs, which then combine with the sperm to make kittens. The female's urge to mate overcomes any memory of the pain from the last mating, which is likely from a year ago. Pain and sex are frequently associated, even in humans, just ask the Marquis de Sade. StuRat 02:25, 5 February 2006 (UTC)

Everyone should take a look at rape. That article defines rape as:

"Rape is a crime where the victim is forced into sexual activity, in particular sexual penetration, against his or her will."

If A forces B into sexual activity, and B is struggling to get away, that's rape. It doesn't matter whether A or B are humans or animals. Bowlhover 01:34, 5 February 2006 (UTC)

Well, I'm not sure what relevance a wikipedia article has to cats, and I'm not sure what 'mother nature' was 'thinking', but I am not convinced that the assumption that because sex is pleasurable to (most) humans, that means it is to animals. There are all kinds of other ways to set reproduction up. Yes, I think sexual pleasure does not necesarily apply to the rest of the animal kingdom. I also think that the concept of 'crime' doesn't apply to animals. For that matter, the concept of 'him' and 'her' doesn't apply to all animals. 67.40.249.122 01:45, 5 February 2006 (UTC)

What about "pain", "pleasure", "affection" and "fear"? Just askin'... ☢ Ҡieff⌇↯ 02:30, 5 February 2006 (UTC)

I don't know. You don't either. 67.40.249.122 02:32, 5 February 2006 (UTC)

They do feel pain, pleasure, affection and fear, pretty much the same way we do. You're being speciesist. Why you say you don't know? Because you're not, say, a cat? That's a really stupid excuse. ☢ Ҡieff⌇↯ 02:47, 5 February 2006 (UTC)

How do you know that? 67.40.249.122 03:17, 5 February 2006 (UTC)

About animal monogamy, there were recently some interesting results regarding female monogamy in bats. If the females were promiscuous, this tended to favor male evolution towards larger testes (to make more sperm to compete) and smaller brains. On the other hand, if females were monogamous, the males evolved to have larger brains and smaller testes [8]. --Uthbrian (talk) 02:39, 5 February 2006 (UTC)

That's interesting - is it just an interesting item, or does it have a relevance to the rape debate? 67.40.249.122 02:46, 5 February 2006 (UTC)

Just an interesting item... I figure I might as well throw that in, with all of the discussion going on about this question :P --Uthbrian (talk) 02:49, 5 February 2006 (UTC)

Yes, rape is a social construct, but so is the basis of most of this discussion. Until and unless 83.5.189.10 returns to explain him/herself more clearly, we really ought to presume that he/she was asking the question in its simplest form, namely: Do all female animals provide "consent" (in whatever sense they are capable of) before sexual intercourse takes place, or are there species where the males forcibly impregnate the females? The answer is the latter. --Aaron 02:48, 5 February 2006 (UTC)

I agree - if the question is 'does sex without consent take place in the animal kingdom take place' the answer is yes. If the question is 'does the human construct of rape have close analogy in the animial kingdom' the answer is we can never know. I think any more argument is largely semantic. 67.40.249.122 02:52, 5 February 2006 (UTC)

So I repeat myself: considering the depth of the questions on the first place, I think you're assuming a bit too much. — Get it now? I'd have expected that if the original user wanted all that much insight, he'd have stated so in the first place. ☢ Ҡieff⌇↯ 03:09, 5 February 2006 (UTC)

I'm sorry - what assumptions are 'too much'? I ask not to provoke more largely futile argument, but because I don't understand your point. 67.40.249.122 03:17, 5 February 2006 (UTC)

"This is very mysterious. What was Mother Nature thinking when she made the very thing that is essential for the survival of the species so painful (and presumably, from the female cat's perspective, undesirable)? What purpose does painful sex serve? If it isn't pleasure that guarantees the continuation of the species, what is it?"

If you mean evolution, it's survival of the fittest, not the one with the least pain. The male cat's penis scraping against the female's vagina stimulates ovulation to begin, and this is useful because it's the only way to start ovulation. Also, from searching on Google, I've found out that some scientists doubt that sexual intercourse is painful for cats. By the way, do you think sex is painful for the male, the female, or both? Bowlhover 05:08, 5 February 2006 (UTC)

Who knows? It doesn't matter whether it is or isn't painful, or whether pain is something cats would understand. Whatever the answer is sheds no light at all on whether a cat can rape another cat. 67.40.249.122 05:24, 5 February 2006 (UTC)

Bowlhover, I have no idea. I was intrigued by Grutness's statement up there that "sex is painful for cats", so I asked some questions. Yes, I assumed it referred to the receptive partner, being the one whose inner parts are being subjected to a spiny penis. And in the context of this entire discussion, which is about whether animals rape animals, it seems quite pertinent to me. If in fact it is painful (which we will probably never know), then I was curious as to whether the tom has to force himself on the female (which may or not amount to rape, depending on your definition), or whether she is a willing participant despite any pain. JackofOz 11:04, 5 February 2006 (UTC)

67.40.249.122, stick a needle into a cat's belly, watch the reaction, then tell me whether you have any doubts that cats feel pain. JackofOz 11:04, 5 February 2006 (UTC)

I agree that it certainly appears that they do. Any denial of that is largely philosophical. The problem is that we don't know what values they attach to it. The pain of rape in humans, for example, is not simply physical, it has societal and psychological elements. I do doubt that these latter exist in cats, and, given that, and the fact that humans do things voluntarily that are nevertheless painful, I think we're on dangerous ground making too many assumptions. 67.40.249.122 17:40, 5 February 2006 (UTC)

I once saw a rooster chase a chicken, force it into a corner and hump her. Judging by the sounds the chicken wasn't too happy about it. Admittedly, I don't understand chickenese, but one can make an educated guess based on sounds chickens make under other circumstances. Now I might as well tell another related tale. In Thailand I witnessed a house warming ceremony that included killing a chicken and throwing it over one's shoulder. A rooster passed by, saw an opportunity and grabbed it (literally). A case of vidi vici veni, where the vici didn't require much of an effort.

Oh, and another example. I once saw a documentary in which some rodent (I think) was said to 'rape' newly borns, which then carried the sperm with them until they were sexually mature and then used it to fertilise themselves. I suppose this was called rape because for humans this would be quite shocking behaviour. But the things is that the animals weren't humans, so the same standard does not apply. Which is not to say that one can not come up with a neutral definition of rape and then see where that applies. Which instantly brings up the question whether rape is necessarily a bad thing. With this approach it wouldn't be, it would just be a neutral description of something. DirkvdM 12:11, 5 February 2006 (UTC)

You're right Dirk - in human terms a crucial element of rape is that it is a crime. I don't think there is an analagous concept, or, at least, we have no way to establish whether it is, in the animal world. A spider, a chicken, or an amoeba may or may not give consent, may or may not enjoy it, it is still not rape. to make non-consensual sex 'rape' you need a system of values that recognises crimes. 67.40.249.122 17:32, 5 February 2006 (UTC)

I believe some birds and mammals do have a concept of "crimes", meaning activities which must be punished by the community, with perhaps the most common punishment being banishment from the group. Obviously, this can only apply to communal animals. StuRat 17:42, 5 February 2006 (UTC)

Sky colour

OK, so the sky is blue because light disperses readily at that frequency, and get's red because of particles in the atmosphere that cause reds to disperse. Why don't we seen green skies?

see green flash. -- Finlay McWalter | Talk 20:44, 4 February 2006 (UTC)

The sky is blue because air scatters short wavelengths more readily than longer ones. During a sunrise/sunset, the sky doesn't get blue because of particles. It gets red because there is more air between the Sun and your eyes, therefore longer wavelengths are also scattered. Bowlhover 20:48, 4 February 2006 (UTC)

I mean, the sky doesn't get red because of particles. Sorry for making that mistake. Bowlhover 20:49, 4 February 2006 (UTC)

Thanks! I thought polution in the sky made skies redder? I know that it's also distance. The green flash page is helpful, but why is it so rare? I mean why don't we see a steady progression of blue->green->red?

Part of the problem is a cognitive/perceptual thing. We understand that the sky will be blue. If you look at the sky critically at certain times such as sunrise and sunset, it is really faintly green, but we tend to ignore this. Artists understand this, and will often paint skies in colours which - if presented just on a palette - would seem unrealistic. However, the eye is far more sensitive to light in the central part of the spectrum than towards the edges, so those times when there is a green tinge to the sky, the sky also seems very pale. So you will never see a deep green sky, though a faint greenish tinge to an otherwise pale sky is quite a regular occurrence. Grutness...wha? 00:17, 5 February 2006 (UTC)

There can never be a completely-green sky. The sky is blue because blue light is scattered the most. The Sun is sometimes red because all shorter wavelengths have been scattered. When green light gets scattered, blue light gets scattered even more, so the sky is bluer than it is green. Also, yes, an increased concentration of dust particles makes skies redder by reflecting the sunlight (which is red at sunrise/sunset). Bowlhover 01:14, 5 February 2006 (UTC)

The article on why the sky is blue is at diffuse sky radiation, not green flash. --AySz88^-^ 04:32, 5 February 2006 (UTC)

Sound Made By Hitting a Large Steel Cylinder

Hello

Does anyone know how to calculate the level of sound (decibels) made when a hammer hits a very large diameter and very long thin walled steel cylinder. I am trying to establish this for the safety of workers in or near the cylinder. An exact number is not really necessary, an order of magnitude or approximation will do.

Thank you for your attention,

Mark

That'd depend greatly on the distance from the source. Also, bear in mind that an order of magnitude makes a great deal of difference on the decibel scale - there's only one order of magnitude of difference between human breathing and a jet engine, for example. As for an answer, I'd say about 90-100 dB at a few metres. GeeJo _{(t) (c)} • 21:17, 4 February 2006 (UTC)

Pardon me? By definition, 10 dB are an order of magnitude. Common Man 21:50, 4 February 2006 (UTC)

Indeed, but the number itself can have an additional order of magnitude (Tetration) GeeJo _{(t) (c)} • 22:15, 4 February 2006 (UTC)

Thank you for the link - I wasn't aware of that term, and the article contains nice pictures. Mark's question was a bit ambiguous, and since I'm not aware of any practical use of tetration, I didn't think this is what he meant. But I see now that you probably just wanted to point out the ambiguity. Common Man 23:35, 4 February 2006 (UTC)

I work at a company where there is quite a safety hazard with loud noises. The only way is to measure the noise with a standard instrument, and to invoke hearing protection if you have any doubt. Otherwise, you are in big crapola with the regulators. --Zeizmic 22:11, 4 February 2006 (UTC)

Hmm, I'm afraid you may be dealing with acoustic events of zeizmic proportions ;-)!

But to take up the challenge of the question. I'd say, we can estimate at least an upper limit for the sound energy by estimating how much energy is exerted by the hammering. To find the energy of a hammer stroke, let's assume a ring-the-bell hammer at a country fair has a weight of 20kg and tosses it 5m up. So we obtain for the energy E = Ug = m*g*h =~= 1000 kg*m²/s² = 1kJ. Now assume the tube is 100% efficient in converting this energy into sound, and you're 1m away and the sound is evenly distributed in all directions (obviously not the case in a tube, but just to keep it simple). Then that energy fills a volume of about V =10 m³ and the pressure p = E/V = 1 hPa. Going to the definition of decibel (by pressure), we get p_dB = 20*log*(p/20µPa) = 20*log*(5,000,000) =~= 20*6.7 = 134dB(SPL). . For 3m distance, you'd get 104db(SPL). Then you need to apply the appropriate Weighting filter, but at least this gives us a good upper limit. That this roughly fits GeeJo's estimate gives me some confidence, but I still could have overlooked an important step. Common Man 23:07, 4 February 2006 (UTC)

I have no idea of what you guys are nattering about, but I think of this as the big gong in King Kong 1933. Something like that is earsplitting, so according to this [9] it is 125 db, whatever the heck that really means. Since it is over 90, it means you better put your pluggies in, or you'll never win your suit against Apple. --Zeizmic 02:12, 5 February 2006 (UTC)

Whatever the noise level, ear damage is also to a large extent a result of extended exposure to noise. I believe that it also matters a lot if one gets some relief time. So 10 minutes in one go would be more damaging than 10 times one minute spread over one hour. Also, a metal tube will produce specific (over)tones in stead of noise, though I don't know if that will have any effect on ear damage. And then there is the question how much working in a noisy environment will affect the mood and therefore productiveness of the workers. Don't rule that one out! Orchestra musicians work under extremely loud conditions and occasionally suffer from severe hearing damage, but want to continue never the less, despite the lousy pay, simply because they love the noise. DirkvdM 12:26, 5 February 2006 (UTC)

February 5

Teleprompter

I read on your site about the teleprompter and who invented the paper and electronic teleprompters for TV. Someone I know here in Las Vegas--Thomas (Thom) J. Knutson, a former cue card man from Hollywood, claims to have invented the teleprompter and then made a fortune selling the idea in Hollywood. Any truth to any of that? Thank you. — Preceding unsigned comment added by 205.188.116.74 (talk • contribs) 22:57, February 4, 2006 (UTC)

If he still works as a cue-card man, then no. And it's not my site, it's his.   freshgavin TALK    08:34, 5 February 2006 (UTC)

I don't see his name in the Teleprompter article. --Aaron 08:44, 5 February 2006 (UTC)

metal

worlds strongest metal

Titanium ? StuRat 04:19, 5 February 2006 (UTC)

Difficult to say, as the strength of a metal depends on how you prepare it and what you do with it, but our article on tensile strength suggests steel. Physchim62 (talk) 04:26, 5 February 2006 (UTC)

Elementary metals or alloys? ☢ Ҡieff⌇↯ 04:38, 5 February 2006 (UTC)

suitly emphazi? --Uthbrian (talk) 04:52, 5 February 2006 (UTC)

Generally, steel alloys are the strongest metals that are useful, but it really depends on the application and what you mean by strength. For example, AISI Grade 18Ni Maraging Steel might be several times stronger than Tungsten, but tungsten might out-perform it in a particular high temperature application. Other important properties to think of are:

• Toughness- how much abuse a material can absorb without failing. Very high strength materials are often brittle and will fail in applications where a weaker but tougher material succeeds. Structural steel alloys usually offer the most toughness bang for the buck.
• Wear resistance- important in abrasive and cutting applications. Hard and Brittle materials can out-preform tougher materials in this application.
• Strength per unit weight (important in the aerospace industry)- Titanium alloys and composites win here (note: pure (non-alloyed) titanium is soft and gummy and not very strong).
• Fatigue resistance- Some high strength or exotic alloys might have a fatigue limit, while other, weaker metals might have an infinite fatigue life in the same application.

See also; Superalloy, Unobtainium, Liquidmetal.--Duk 08:17, 5 February 2006 (UTC)

Adamantium followed closely by Rearden Metal. :-) Dismas|^(talk) 09:03, 5 February 2006 (UTC)

Revoked SSL certificate

What does a revoked (Status = "REVOKED"), yet still-valid (Validity period start <= Current date < Expiration date), SSL certificate (actively being used in a server with https:// protocol) really mean for its site visitors? 61.94.148.164 05:04, 5 February 2006 (UTC)

It's hard to know why the cert was revoked: perhaps a commercial matter between the cert authority and the cert owner (like they didn't pay their bill), perhaps a technical issue (like an update hasn't been pushed to the correct server), or perhaps a genuine revocation (actioned perhaps because the security of the associated secret information was compromised). Whatever the reason, the conservative thing to do is to not trust it. -- Finlay McWalter | Talk 05:12, 5 February 2006 (UTC)

Elbino effect in humans

I would like to find out if you find elbino mutation in all human ethnic groups? I am only aware of this accuring in African people (black people).

I don't know if albinism occurs in all ethnic groups, but it certainly is not restricted to black Africans. I have known some Caucasian albinos. William Spooner (who have rise to spoonerisms), was a famous albino Englishman. Check out here for more information. JackofOz 05:27, 5 February 2006 (UTC)

The only two albinos I have ever met were a European ("Caucasian") and a New Guinean (i.e., Melanesian). The mutation seems to occur in a wide variety of ethnicities. Grutness...wha? 12:20, 5 February 2006 (UTC)

Johnny Winter is an albino. And I think Heino is too. Of course, albinism would be an obvious read, though I don't know if it has an answer. It does name the son of a Signaporean PM as an albino, but then one would have to know the whole ethnic background. DirkvdM 12:29, 5 February 2006 (UTC)

Interesting that "negro" (meaning "black") is considered offensive these days, but "albino" (meaning "white") isn't. JackofOz 12:40, 5 February 2006 (UTC)

Is it? Doesn't that also depend on which part of the (English speaking) world you're in? By the way. in Dutch, the neutral word is 'neger', which is obviously derived from 'negro'. DirkvdM 13:45, 5 February 2006 (UTC)

I believe that it can happen in any ethnic group. By the way, it's spelled "Albino" - Cybergoth 17:42, 5 February 2006 (UTC)

Microwaves

If a 2000-watt microwave oven will heat my soup in 5 minutes, will a 2 megawatt microwave oven cook it in 0.3 seconds without any side-effects? --Shanedidona 05:25, 5 February 2006 (UTC)

Not any more than if a conventional oven at 500 degrees cooks a turkey in an hour an oven at 5000 degrees will cook it in 6 mins. In both cases, the outside will burn and the interior will stay cold. You need time to allow the heat to distribute itself evenly. Stopping it and stirring will certainly help. Too bad you can't stir a turkey. StuRat 07:52, 5 February 2006 (UTC)

And even if you could, it would be hard to stop it and take it out within the 0.3 second interval.   freshgavin TALK    08:29, 5 February 2006 (UTC)

Oh yeah, and when was the last time you saw a 2-megawatt microwave oven without a timer that you could set in 10ths of a second? Hmmmmm??? :-)

Seriously, it's true that microwaves don't just heat food on the surface the way a conventional oven does, but heating does not extend evenly throughout the food. Most of it is in the outer layers, and even then it isn't uniform due to formation of interference effects such as standing waves (things like deflector fans and turntables only reduce the non-uniformity). StuRat is right: probably some parts of the soup would boil explosively while other parts didn't warm enough. --Anonymous, 08:54 UTC, February 5, 2006.

I guess you would have to spread the soup in a thin layer on a very wide dish to get away with this. Obviously, your oven would have to be specially shaped too.

I believe the ideal shape is a thin circle with a thicker ring at the edge. I would like to offer a line of microwaveable dishes with this shape, or alternatively, frozen foods in containers with such a shape. Perhaps it should be called donutware or torusware (as anusware is unlikely to sell :-)). StuRat 09:06, 5 February 2006 (UTC)

Oh dear, there's a language called 'anus' it seems. That could easily become the butt of some anal jokes, such as referring to the fact that speaking is also done through an orifice. I won;t lower myself to that level, though. DirkvdM 12:43, 5 February 2006 (UTC)

I envision a language featuring a variety of fart sounds: "No Timmy, you only make the wet fart sound when asking a question." 16:46, 5 February 2006 (UTC)

I'm invisioning trailers for the movie Jetsons 5000 in a time where all food is microwavable and all microwaves are 2-megawatts and all food containers and microwaves are giant 2 meter diameter discs hanging from the roof of their ultra-house. Unfortunately the microwave doesn't have a digital keypad and you have to 'dial in' the timer.   freshgavin TALK    10:54, 5 February 2006 (UTC)

I actually prefer dials to digital pads. My current mic has one dial for time and one for power level. It has a handle you pull to open, not a button you have to depress. It has no digital display. I can't stand those electronic pads where you have to enter info in a specific way to get it to cooperate and need to re-enter the time after every power glitch to prevent it from flashing 12:00 all the time (like a VCR). Also, on a TV which lacks a volume dial, it's impossible to turn it on and turn the volume down in the early morning hours without waking everybody in the house. With a dial you can turn the volume down before even turning it on.

Another example of technology run amok is the digital "temperature control system" on my truck. In order to receive "permission" to switch to recirc mode when the truck in front of me is belching diesel fumes, I must first page thru the menu until I set it to the face vents position, otherwise it will flash a red light at me that means "access denied". Good luck doing all that while driving. Then, when I turn the vehicle off, all the settings go back to the defaults, as opposed to a manual system which would damn well leave it how I had set it. I guess I will just have to get used to looking (and coughing) like a chimney sweep. Well, I enjoyed my good morning rant, did you ? StuRat 14:44, 5 February 2006 (UTC)

Why is there a star beside the title of this section? Microwaves isn't a featured article--Shanedidona 14:30, 5 February 2006 (UTC)

I guess it's a featured question. GeeJo _{(t) (c)} • 15:12, 5 February 2006 (UTC)

2 questions (Quantum)

• Why do the Hermite polynomials can be applied to solve the Quantum harmonic oscillator ?

$H_{n}(x)=(-1)^{n}e^{x^{2}}{\frac {d^{n}}{dx^{n}}}e^{-x^{2}}$ Hermite polynomials

$H={p^{2} \over 2m}+{1 \over 2}m\omega ^{2}x^{2}$ Quantum harmonic oscillator 's energy

--HydrogenSu 12:14, 5 February 2006 (UTC)

• Shouldn't the Ĥamiltonian, have a ĥat?--64.12.116.74 17:45, 5 February 2006 (UTC)

Within atoms, why do the electrons not crash into the nucleus?

As electrons and protons are oppositely charged, why do the negatively charged electrons not fall toward the positively charged protons at the center of the atom? Does this ever happen naturally, can electrons be forced to do this, and what is the result if it has be achieved?

• Well, there are a couple of answers to that, depending on how sophisticated you want to get. If you keep to the good old planetary model as worked out by Ernest Rutherford and his ilk, then it's the same reason that the planets don't crash into the sun even though gravity is pulling them in: the tangential velocity is such that the attractive force causes the electrons to orbit. If you go for one of the more complicated quantum models, then there's a whole bunch of interacting forces that create different energy levels such that an electron is much more likely to inhabit a particular space around the atom (called an orbital) that generally doesn't include the nucleus itself. Confusing Manifestation 13:20, 5 February 2006 (UTC)

I know the planetary model, of classical physics, doesn't adequately explain the phenomenon. So it looks like I want to get more sophisticated than that, into quantam physics. I read somewhere that that the planetary model has been disproven. Yes thanks, I know its called an orbital, thanks. No need to be rude. The site asks that question posters do as much research of their own to try to find the answers to their questions to avoid unnecessary posts. I have researched this enough to know what an orbital is. Does anyone actually know the answers to the originally posted question, other than postulations and contrived hypothoses?

In the early 20th century,Franch de Broglie published a theory of "particle-wave alike". It explained how an ${\mathcal {,}}e^{-},$ not fall onto/crash on nucleus. Please see[10] if you'd be pleased.--HydrogenSu 14:40, 5 February 2006 (UTC)

(I think that don't need to write "a/the" in question marks.And should be "onto" nucleus not "into". Because of impossible going through nucleus,there exist some strong-actions in them.)--HydrogenSu 14:47, 5 February 2006 (UTC)

• I have a little want to explain. Your question answering briefly as:When electrons on their orbitals satisfy standing-wave conditions then they keep steady without radiating any photons.--HydrogenSu 15:01, 5 February 2006 (UTC)

The description of the first atomic orbital results from the solution to the Schrödinger wave equation for hydrogen-like atoms. Effectively, the electric potential disappears very close to the nucleus, so the probability of finding an electron "on" the nucleus is actually close to zero. ‣ᓛᖁᑐ 14:57, 5 February 2006 (UTC)

Thank yous, HydrogenSu and the others, for your thoughtful responses. I have followed the links and am amazed by this idea of the wave structure of matter. I must find out more about it. First, are you saying that some greater force within the nucleus repels the electron while a lesser force (the positive proton) attracts it, thus keeping it relatively balanced as it journeys about in a region that forms the orbit? ( I know that the orbit is only an estimate of about 90% of where the electron would probably be located)

If this is what you mean, then what is the name of this repulsive force? Secondly, one of you mentioned that as the electron approached the nucleus it would lose its charge. Why? and how is this known?

                                                --Leah

NoNo...Strong interactions(forces) in nucleus belong to some short distance interactions. They will not influe further space,or we early found Unified Field Theory. Electrons do not crash on nucleus just for the reasons of they belonging to quantilizational particles and accepting quatum energy only. So also radiate quatum EM-waves,called photons. If any questions,I'd be pleasured to discuss with.--HydrogenSu 16:52, 5 February 2006 (UTC)

The classical equations of motion for an electron orbiting a nucleus are exactly the same as those for a planet orbiting a star, just with different parameters. However, at the end of the 19th century, I was realised that whenever charges accelerate (and circular motion is a form of accelerated motion), they must lose energy via radiation. The natural conclusion is that the electron should slowly lose all its energy and spiral inwards towards the nucleus. Naturally this doesn't occur in nature. The problem was solved in the early twentienth century with Quantum mechanics (QM)

In QM, particles exist in various states. These states have information about probablities of the electron's position and momentum at various times. In each situation, there are only a few states that are allowable. Allowable states satisfy something called the Schrodinger equation. When you analyse the mathematics of the hydrogen atom, it becomes clear that there are discrete states. The lowest state, called the ground state, corresponds to an electron orbiting the nucleus at a radius r. The mathematics of the Schrodinger equation rule out any state where the electron 'is' at the nucleus, or orbiting at a radius less than r. Since these states aren't allowed , the electron does not (cannot), move closer to the nucleus. Dmn € Դմն 16:56, 5 February 2006 (UTC)

Finding an article

Is there some way I can search the list of articles alphabetically when Wikiwax is down? --Shantavira 12:46, 5 February 2006 (UTC)

Try this quick index. Bowlhover 14:43, 5 February 2006 (UTC)

Thanks. That's exactly what I wanted. Wikiwax seems to have been down for the past couple of days... --Shantavira 15:08, 5 February 2006 (UTC)

Maybe WikiWax has melted or been attacked by a giant Q-tip. StuRat 16:40, 5 February 2006 (UTC)

Coal-to-Oil Processes

I've heard/read that Coal can be turned into Oil, (as in the kind of oil for use as automotive fuels and many other useful things in life.)

What is the newest and/or most effective method to do this, and is there an article about it? --Shultz 13:34, 5 February 2006 (UTC)

See Coal#Liquefaction. --Heron 15:10, 5 February 2006 (UTC)

Standing Waves' Math Expression

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.

• One more question that what's difference between phase velocity and group velocity? My opinions and thoughts:

By their math expression we can clearly find angular frequency of ${\mathcal {V}}_{p},$ ${\mathcal {\omega }}$ which keeps constant when a wave vibrates up and down localized. That may because of energy transports into a wave is conservative,just like a particel moves up and down in a Y axis,localizedly(which keeps energy conservative).

But for another one,it travels in an X axis,that hints its phase-angular is the function of time. By time changes,then ${\mathcal {\omega }}$ naturely changes either.

I'm a little not sure above. Could anyone discuss with me?--HydrogenSu 15:07, 5 February 2006 (UTC)

Yes, could someone please discuss further? At this point I am understandably confused. Are you saying that standing wave theory may be flawed, or is false? Or is a paradox in that, mathematically, can be both proven true and false? Mostly, how does this all relate to my original question, why an electron wave/particle could never approach the nucleus? Or could it? --Leah

I think the questions I proposed above won't contradict anything by sientists last century. I just can't understand why their multiples are 0 ? Is it about phase velocities independance with group ones? I'm confused.

The standing wave model is the production in early quantum theory. Schrödinger equation and Heisenberg's theories are better. It's not wrong but is an elder model.--HydrogenSu 16:37, 5 February 2006 (UTC)

• LoL, Standing Wave Functions--64.12.116.74 17:43, 5 February 2006 (UTC)