Wikipedia:Reference desk/Science

Reference Desk

Science Mathematics Computing/IT Humanities Language Entertainment Miscellaneous Archives
How to ask a question Search first. It's quicker, because you can find the answer in our online encyclopedia instead of waiting for a volunteer to respond. Search Wikipedia using the searchbox. A web search could help too. Common questions about Wikipedia itself, such as how to cite Wikipedia and who owns Wikipedia, are answered in Wikipedia:FAQ.
Sign your question. Type ~~~~ at its end. Be specific. Explain your question in detail if necessary, addressing exactly what you'd like answered. For information that changes from country to country (or from state to state), such as legal, fiscal or institutional matters, please specify the jurisdiction you're interested in. Include both a title and a question. The title (top box) should specify the topic of your question. The complete details should be in the bottom box. Do your own homework. If you need help with a specific part or concept of your homework, feel free to ask, but please don't post entire homework questions and expect us to give you the answers. Be patient. Questions are answered by other users, and a user who can answer may not be reading the page immediately. A complete answer to your question may be developed over a period of up to seven days.	Do not include your e-mail address. Questions aren't normally answered by e-mail. Be aware that the content on Wikipedia is extensively copied to many websites; making your e-mail address public here may make it very public throughout the Internet. Edit your question for more discussion. Click the [edit] link on right side of its header line. Please do not start multiple sections about the same topic. Archived questions If you cannot find your question on the reference desks, please see the Archives. Unanswered questions If you find that your question has been archived before being answered, you may copy your question from the Archives into a new section on the reference desk. Do not request medical or legal advice. Ask a doctor or lawyer instead.
After reading the above, you may ask a new question by clicking here. Your question will be added at the bottom of the page.
How to answer a question Be thorough. Please provide as much of the answer as you are able to. Be concise, not terse. Please write in a clear and easily understood manner. Keep your answer within the scope of the question as stated.	Link to articles which may have further information relevant to the question. Be polite to users, especially ones new to Wikipedia. A little fun is fine, but don't be rude. The reference desk is not a soapbox. Please avoid debating about politics, religion, or other sensitive issues.

Ultraviolet light

Does ultrviolet light have a heat index. Could it increase the heat of a pond, stream, river, or ocean? --anon

Any energy in the electromagnetic spectrum can be converted into heat, so yes. — Lomn | Talk / RfC 02:09, 19 September 2005 (UTC)

More fun with PC 800 RAM!

Hey, true believers - so, I bought some used RAM for an old Gateway 700S desktop I have. Figure I can get a little life out of the new system this way. Only problem is, I seem to have purchased PC 800-[b]45[/b] RAM. My computer only seems interested in taking PC 800-[b]40[/b] RDRAM. Is there any way to force my computer to accept the new RAM in a way that does not compromise its functionality? Thanks. --Brasswatchman 02:36, 19 September 2005 (UTC)

Of all things, why should deletion and moving of files slow my computer?

I'm asking out of curiosity rather than dire need, since it's rarely an issue. Here's the thing:

My computer's fairly old by most people's standards, 200mb RAM, 133mhz, still running Win98. However, it serves me well, rarely giving me any problems, I can do pretty much everything I need to do with it and plenty of stuff I needn't: it gets lots of use and rarely complains.

What puzzles me is that occasionally I manually go through all the folders and files just to chuck out clutter and sometimes I've been very lazy about where I put my creations, so I do some tidying of files etc.

After a while of deleting and moving files my system slows to a crawl beyond anything that seemingly more intensive tasks (listening to audio files, streamed radio, playing a game with some graphical content, looking at flash animations etc) does.

It slows down horribly (moving one file from one folder to another can take 20 seconds, opening another folder in explore view takes 30 seconds). Why should that be? It's all solved with a reboot, as you may guess. --bodnotbod 02:43, 19 September 2005 (UTC)

How often do you compress your disk space, that is to say run the utility to clean up the spaces on disk space between chunks of data? I also have Win 98 and I use Norton Utilities Speed Disk for this purpose. It is possible that if your disk space is severely fragmented, such that the sizes of the spaces are not big enough for the files you want to move, or if it has to search through a lot of spaces to find what is needed for the move, that would explain part of the problem.

I also find it neccessary to reboot my PC when it starts to go sluggish ... in my case it goes sluggish after

• I spend a modicum of time on the Internet, like here at Wiki;
• Do some heavy duty keying in e-mail or other word processing;
• Do some real work telecommuting to the office;
• Play some old fashioned DOS games.

I suspect that some activities are not doing a good job of returning memory and other rsources when finished, meaning the resources not being used effectively on the next task that I wish to run.

AlMac|^(talk) 04:38, 19 September 2005 (UTC)

• Ah, yes, I shall definitely defrag my drive later. I tend to do that very rarely. Although, perhaps because I tend not to download very much or install new software I can leave it for quite a long time and still get "your disk is only x% (where x is a small integer) fragmented and doesn't require...". I don't tend to have trouble with the other things you mention, in particular using the net and sending emails which I spend the bulk of the time using this for. Anybody else have something to add? --bodnotbod 17:29, 19 September 2005 (UTC)

Yes, close any apps that you're not wanting to use real soon and empty your browser's cache. --hydnjo talk 19:24, 19 September 2005 (UTC)

I close the apps when I'm doing one of the cleaning sessions. Not sure I want to delete my browser cache: it comes in handy. --bodnotbod 02:12, 20 September 2005 (UTC)

what is the discipline of logic

You might want to start at logic. -- Rick Block (talk) 03:06, 19 September 2005 (UTC)

According to Galen, the venous and arterial systems were separate. This was the prevalent view in medicine until:

William Harvey -- Jmabel | Talk 03:55, 19 September 2005 (UTC)

Galen also has the answer, though I suspect your textbook would as well. Garrett Albright 03:59, 19 September 2005 (UTC)

But see also Ibn Nafis, who described the circulation of the blood in 1242 (though his work was forgotten and did not influence the prevalent view). Gdr 10:35, 19 September 2005 (UTC)

refrigerator humidity drawers

My fridge has two humidity drawers; one labeled high humidity, and one labeled low humidity. I'm just learning the ways of fridges, and I have some vegetables that are starting to wilt. Can you tell me what the two drawers are for, and which one my broccoli is supposed to go in? -Lethe | Talk 05:10, 19 September 2005 (UTC)

From a layman standpoint, I'd go with things that stay moist and things that don't. Since fresh broccoli is usually under a mister at a grocery store, I'd assume it's high-humidity and put it there. As for low... apples maybe? I'm not sure. — Lomn | Talk / RfC 05:15, 19 September 2005 (UTC)

• High humidity: leafy vegetables. Medium humidity: apples, grapes, other thin-skinned fruits. Low humidity: Citrus fruit. Keep the broccoli in an open bag (or a perforated plastic bag) in the crisper (the other name for the high humidity bin.) --jpgordon∇∆∇∆ 05:23, 19 September 2005 (UTC)
• On a related note, am I right to assume that the drawer next to my crisper, marked for meat, is simply a low humidity drawer? — Laura Scudder | Talk 05:41, 19 September 2005 (UTC)

So the high humidiy drawer is for vegetables, and the low humidity drawer is for meat? sounds good to me. -Lethe | Talk 05:44, 19 September 2005 (UTC)

On some brands/models some cold air (from the freezer) is piped into the meat and low humidity bins. This has the additional effect of lowering the temperature by 2 or 3ºF. --hydnjo talk 19:15, 19 September 2005 (UTC)

aeroplane

what are the parts of an aeroplane and what are their funtion???

Uh...how much detail do you need? (Don't forget the wings, and does the pilot count as part of an aeroplane?)--inks 09:44, 19 September 2005 (UTC)

You probably want to check out control surfaces and Category:Aircraft controls. — Lomn | Talk / RfC 13:09, 19 September 2005 (UTC)

Also Flight controls. DJ Clayworth 14:02, 20 September 2005 (UTC)

How does asparagus grow?

Arr, sparrow-grass grows much like reg'lar grass, matey. I suggest ye be readin' our article at asparagus for more. Garrett Albright 12:13, 19 September 2005 (UTC)

What is formed from ammonia and the breakdown of simple sugars

Is this a homework question? (If so, please see the notes at the top of this page). Notinasnaid 10:42, 19 September 2005 (UTC)

urinary system

(no question)

• What would you like you like to know about the urinary system ? Notinasnaid 11:06, 19 September 2005 (UTC)
• You're not just taking the...sorry. DJ Clayworth 13:59, 20 September 2005 (UTC)
  • It's when you're boredly reading something and you come across these little gems of beautiful humour that you realise why you do this. Thanks. Rob Church ^{Talk | Desk} 00:05, 21 September 2005 (UTC)

Gigabyte

Hi, I was just wondering... How many characters (text-wise) could fit into a gigabyte? Cirrial 11:34, 19 September 2005 (UTC)

• Like most questions, the answer is "it depends"...

For someone from the western world, they are used to working with characters that occupy exactly one byte. "An egg" would use six bytes. Note that spaces and new lines are all characters (a new line is often two characters). In this case, a gigabyte would hold exactly as many characters as bytes in a gigabyte. But how big is a gigabyte? Either two to the power 30 or ten to the power 9, respectively 1073741824 or 1000000000. If we say "about a thousand million" we won't be far wrong.

So, for many people in the western world, about a thousand million characters. But what about people outside the western world? In Japan, they often use a system where a character fits in two bytes. So in this system, the Japanese could get about 500 million characters.

Many people, all over the world, use a system called Unicode. There is more than one kind of Unicode. If they use a kind called UCS-2, every character is 2 bytes. That means that if you use UCS-2, you get about 500 million characters, no matter what language is used. Another kind of Unicode is called UTF-8. In this, non-accented English letters use one byte, european accents use two bytes, and Japanese uses three bytes. So it really depends now, somewhere between 300 million and 1000 million characters.

This all assumes a file contains nothing but text. In Windows terms, a TXT file. Other types of file may have overheads so there are less characters than you would get in TXT, or compression, so there are more characters. DOC files have overhead, so it is less characters (of the actual text). PDF files have overhead and compression and may well get more characters than a TXT in some cases (not others).

Clear now? Notinasnaid 11:46, 19 September 2005 (UTC)

• See Gibibyte, Gigabyte, and UTF-8. Bovlb 14:46, 19 September 2005 (UTC)

Is light matter?

Why don't you check out light and matter. — Laura Scudder | Talk 15:52, 19 September 2005 (UTC)

No, it is not. Light is made up of photons, which are massless. Besides, photons are bosons, not fermions out of which matter is made. —AugPi 05:58, 20 September 2005 (UTC)

Minor nitpick—while the protons, neutrons, and electrons of which matter is made (mostly) are fermions when examined individually, in some composite particles they become bosons. Helium-4 atoms, for instance, are bosons. TenOfAllTrades(talk) 07:06, 20 September 2005 (UTC)

Many hands make light work. --Sum0 20:38, 21 September 2005 (UTC)

un authorized access to computers

ho ppl ive got an assignment to make for university..and i really need some help. the topic is "Discuss and describe how we can stop unauthorized access to our computers?" please send me as much research on this topic as possible.. thx.bye

Arr, who you be callin' a "ho ppl?" You be walkin' the plank in a moment, but first I be suggestin' you check out our articles on computer security and computer insecurity. Arr. Garrett Albright 16:31, 19 September 2005 (UTC)

Ahoy! In case any of ye landlubbers be wondering, today (September 19) is ITLAPD: International Talk Like a Pirate Day. Arr. TenOfAllTrades(talk) 16:56, 19 September 2005 (UTC)

Aw come on, it's like fight club. You're not supposed to tell them it's fight club! :) - Taxman ^Talk 18:54, 19 September 2005 (UTC)

You can start with articles

• computer security talks about how to design computer systems so that they are secure.
• computer insecurity talks about the reality that most people, companies, governments, being in a world in which there are cheap insecure computers, and expensive secure computers, buty the cheap ones, then spend enormous time and expense to deal with the insecurity problems.
• I started on computer security audit and when time permits (I been extremely busy of late), clean it up some more so it conforms to Wiki style. This talks about a type of checking that can be used to dramatically reduce the cost and time and effort needed to make insecure systems more secure, and identify what areas of education its owners and managers need in the area of improving security.

AlMac|^(talk) 18:02, 19 September 2005 (UTC)

DNA computing magazines

What are the most distinguished scientific magazines for DNA computing? Can you point me to any good review-articles? -EnSamulili 16:16, 19 September 2005 (UTC)

Academic magazines usually don't come along until a research area has been around awhile. Research will start in related conferences, then get its own. You might start here and then start looking up author names on scholar.google.com and following bibliographic references. Lunkwill 09:41, 22 September 2005 (UTC)

How do I get rich

Hey how do I become really rich and also maybe famous. Cheers. -JoeMoe

You could become rich by winning a lottery a time or two. Once rich, proceed to behave eccentrically and fame (or at least undue media attention, which is almost as good) will shortly follow. Alternately, rob a bank. Infamous is the same as maybe famous, right? — Lomn | Talk / RfC 18:47, 19 September 2005 (UTC)

Ayy, shiver me timbers, edit conflict. If you check the archives, matey, this question has been answered before. But basically getting rich requires either producing the value yourself or stealing it. The first way involves producing a good or service that other people are willing to pay more for than it costs you to produce. That may be making a widget or hitting a golf ball really well. Stealing could be direct, or embezzling. Ask the Tyco guys and others how that went for them. As to getting famous, simply do something or be something that people want to talk about and think about. That may be personality, acting, doing really dumb or really smart things, or being really wealthy. - Taxman ^Talk 18:51, 19 September 2005 (UTC)

Also, on no account consider sending money to anyone advertising who claims they will make you rich. You may, however, consider placing such an ad yourself, though this road to riches is paved with criminal convictions. But also consider "There is a tide in the affairs of men / Which, taken at the flood, leads on to fortune." - William Shakespeare. I've always been drawn to that quote, I think it sums up very well the money made by a) being at the cutting edge and b) fads. So it accounts for the fortunes of the dot-com boom and Furbies alike. --bodnotbod 02:08, 20 September 2005 (UTC)

A rhetorical answer to a rhetorical question: by some standards you already are rich. You have a computer or access to one, you have the time on your hands to ask this question, you probably have more stuff than you need, you probably don't want to earn your own stripes, and you most likely, don't want to hear any of this. Oh well and too bad, you asked. --hydnjo talk 02:24, 20 September 2005 (UTC)

Becoming famous is easy. Get a Wikipedia account. Make lots of useful edits, write some needed articles, and get them up to featured article standard. Voila, you're famous. Fortune is sure to follow.-gadfium 05:07, 20 September 2005 (UTC)

Barring theft and luck, the best way to make money is to already have it. The next necessity is brains to make it multiply. Alas I cannot provide them for you :) . As for the initial money, you might try a bank, but you won't be the first one not to succeed there. The faster you want to get rich, the more spectacular your idea will have to be and the less likely it will be you get money for it. Sorry. DirkvdM 11:40, 21 September 2005 (UTC)

auto alternators

just read your article on alternators - i have an older car with an alternator without a built in regulator - the car presently has a voltage meter which i would like to remove by adding a diode to the system - the diode would connect to the alternator and to the warning light in the car - need a diode that could be wired to the ignition such that the light would be lit when the car ignition is on but would turn off when the alternator was producing at least 13 volts - is this part available - if so could you refer me to the source - thanks in advance for the help - love your site

I don't think a simple diode is quite what you're after, though I haven't found quite what you're looking for. I know something along the right lines exists, however; most modern vehicles are fitted with a light that goes on when the alternator's not producing anything and the battery is being drained. Maybe you'll have to visit an auto electrical supply shop.

Though I'm a little confused as to why you'd like to remove the volt meter. Is it spoiling the appearance of your car? --Robert Merkel 04:40, 21 September 2005 (UTC)

There's a reason they call them idiot lights - gauges are much more useful in warning you of a problem. Anyways, if you REALLY want to do this, you probably need a zener diode. - Bloodshedder 02:54, 23 September 2005 (UTC)

global ecosystem

The global ecosystem is also known as the Earth's (this is where the answer goes)?

See Ecosystem. --hydnjo talk 01:14, 20 September 2005 (UTC)

Different link styles on one webpage

How can I put different link styles on one page? I want the links in a menu sidebar to be block and not-underlined; text links in the text to be inline and underlined; and image links in the text to be inline without a border (like the speaker we use for audio samples on Wikipedia). Bonus question: how can I get the audio samples to play without loading Quicktime in a new page? I want the reader to be able to continue reading the article while the sample downloads and plays. Thanks in advance, Mark¹ 02:12, 20 September 2005 (UTC)

• To change particular links, you need to meddle with User:Markalexander100/monobook.js. I don't know which id the side menu has, but I'm pretty sure you can change those links seperately from the rest. For the other question: simply install foobar and set it to play .ogg files by default. Tada no more new Quicktime window. If you're using Mozilla Firefox, there's an extension that let's you incorporate certain media players into your browser without opening additional windows. - Mgm|^(talk) 08:27, 20 September 2005 (UTC)

Sorry, I was unclear. The link formats I want are for a website which I'm producing, not for Wikipedia. And I want readers of the site to be able to play the samples without opening a new page, (ideally) whatever browser they're using. Thanks, though. ;) Mark¹ 08:52, 20 September 2005 (UTC)

You want to use Cascading Style Sheets, segregating your styles by general location on the page. You should define common styles (like text color) without prefix, and then prefix contextual links with their containing element (a <div> works well). Also note that the image links will have most of their styles on the image, not the link. Here's a quick sample:

a { color: #00F; }
#sidebar a { text-decoration: none; display:block; }
#maintext a { /* nothing past default needs definition */ }
a img { display:inline; border-width:0; vertical-align: middle; }

Also, W3Schools is a pretty good reference site for CSS. — Lomn | Talk / RfC 13:08, 20 September 2005 (UTC)

Thanks a lot- I'll give that a go. Mark¹ 01:43, 21 September 2005 (UTC)

chalk blocks

How is chalk made into blocks from powder form. nellie

• Did you mean blackboard chalk? Well, if you did, blackboard chalk is genrally not chalk (limestone) but gypsum. Our gypsum article says that gypsum has an "unusual property: when mixed with water at normal (ambient) temperatures, it quickly reverts chemically to the preferred dihydrate form, while physically "setting" to form a rigid and relatively strong gypsum crystal lattice". I think this basically means that if you you wet powdered gypsum, mould it and let it dry, it keeps the new shape: blackboard chalk. If you are more specific we can help you further. --Commander Keane 07:09, 20 September 2005 (UTC)

Paper vs. Trees

How many pieces of 8 1/2 x 11 or A4 paper would you need to conserve to save a single tree?

And how many angels can dance on the head of a pin and how many roads must a man walk down ... --hydnjo talk 03:56, 20 September 2005 (UTC)

Industry produces paper in vast, bulk quantities, driven by market forces. You would need to interrupt supply and demand in some way. ‣ᓛᖁ♀ᑐ 04:27, 20 September 2005 (UTC)

• I think it's vaguely possible -- don't quote me on this, though -- that the questioner may indeed have been wondering how many sheets of paper you get from a single tree. --jpgordon∇∆∇∆ 05:19, 20 September 2005 (UTC)

You could make a rough estimate by weighing a ream of paper and dividing it by 1000 ( I thnik there are a thousand sheets ina ream). Then you could compare this mass with the mass of a typical felled tree (Which I don't know but someone else might) Theresa Knott (a tenth stroke) 05:22, 20 September 2005 (UTC)

Actually there are 500 sheets of paper in a ream. --WhiteDragon 20:55, 26 September 2005 (UTC)

I suspect a major flaw here. Paper is largely dry and wood probably contains more than 90% water, so you might have to multiply the result by ten or something (ie you would need ten times as many trees). DirkvdM 11:45, 21 September 2005 (UTC)

A minor flaw, too...a significant weight of kaolin goes into white paper. It's not all pulp.--Joel 06:19, 27 September 2005 (UTC)

There's a start here, though these seem to be paper industry stats. - Nunh-huh 06:44, 20 September 2005 (UTC)

• There is a misconception here. Paper companies plant trees to make paper from, based on consumer demand. If people start buying less paper, they plant fewer trees. Using less paper does not "save" trees.

  On the other hand, as noted by jpgordon, we can still ask how many sheets of paper can be made from one tree. Based on the link provided by Nunh-huh, we can get 89,870 "sheets of letterhead bond paper" from a cord of wood, and 10 – 15 cords from an acre of forest. Thus: 898,700 – 1,348,050 sheets from an acre. Now all we have to do is figure out how many trees are typically in an acre. Random Google searches produce numbers like 25, 50, or 100. So let's say 25 – 100 trees per acre. Dividing, we get 8,987 – 53,922 sheets per tree. In summary, it varies, but 10,000 – 50,000 is probably a decent estimate.

  — Nowhither 18:01, 20 September 2005 (UTC)

• Without wishing to turn this into a brawl over logging practices, that's rather an oversimplification. Some paper companies clearfell old growth native forest which is then turned into paper. Sure, they replant the trees afterward, but the forest does not recover its biodiversity for many years afterwards, if ever. See Gunns Limited, for instance. --Robert Merkel
  • Yes, that's true. The replanted trees are not there to make a forest; they are there to turn into paper. Tree farms, like most farms, are monocultures. But then it gets really tricky. Why do we want to "save trees"? If global warming is your concern, well, a tree farm is probably a fine way to sequester carbon. And with someone watching carefully to prevent it from burning, I suppose it is probably better for carbon sequestering than a natural forest. In any case, higher demand for paper is definitely going to increase the total tree biomass in the world. So if you want to prevent the Antarctic ice sheets from melting, then buy lots of paper. On the other hand, if biodiversity is your goal, then buy less paper. What if you like both? That's really hard. — Nowhither 23:24, 21 September 2005 (UTC)

Don't forget production and disposal costs of the paper. All of that burns hydrocarbons. Lunkwill 09:33, 22 September 2005 (UTC)

Also, people seem to be missing the fact that not all logging companies replant at all. Some just move on. Superm401 | Talk 21:19, 23 September 2005 (UTC)

I recall seeing a poster at my school claiming that conserving 118 pounds of paper is equal to saving one tree. Sorry, but I havn't got a source or anything to back me up.

Well, I'm afraid that poster was quite wrong (not that one shouldn't conserve paper). — Nowhither 00:58, 23 September 2005 (UTC)

phosphatidylserine for brain function

• And your question is? - Mgm|^(talk) 08:29, 20 September 2005 (UTC)

How does Kate's tool work

Could you give me a general explanation on how something like Kate's tool works. I'd ask User:Kate but they are probably rather busy. The only language I know is MATLAB, so a qualitative response would be appreciated. --Commander Keane 07:35, 20 September 2005 (UTC)

I presume it queries the database (no idea if directly or indirectly via something like Special:Contributions) and parses a list of edited pages for known prefixes like Wikipedia: or User talk:. Any entry without such a prefix is in regular article space and is counted as such.

All that said, there shouldn't be any problem dropping Kate a quick note asking for a simple (and correct) answer. — Lomn | Talk / RfC 13:18, 20 September 2005 (UTC)

You're not all that wrong. It will most likely issue a couple of SQL statements to the MySQL server, using the database specified in the drop-down box. The queries are likely similar to these:

User ID: SELECT user_id FROM user WHERE user_name='(your user name)';

I'll refer to this value as UID from here...

Total edits: SELECT COUNT(cur_id) FROM cur WHERE cur_user=UID;
             SELECT COUNT(old_id) FROM old WHERE old_user=UID;

Those two are added together, obviously.

Distinct pages edited:  SELECT COUNT(cur_id) FROM cur WHERE cur_user=UID GROUP BY cur_title;
                        SELECT COUNT(old_id) FROM old WHERE old_user=UID GROUP BY old_title;

Again, added together.

Edits/page (avg) is calculated as ${\frac {DistinctPagesEdited}{TotalEdits}}$.

First edit: SELECT cur_timestamp FROM cur ORDER BY cur_timestamp ASC LIMIT 1;
            SELECT old_timestamp FROM old ORDER BY old_timestamp ASC LIMIT 1;

from which the smallest is selected (assuming both queries return a value)...

Edits by namespace: SELECT COUNT(cur_id) FROM cur WHERE cur_user=UID GROUP BY cur_namespace;
                    SELECT COUNT(old_id) FROM old WHERE old_user=UID GROUP BY old_namespace;

For each namespace, the values are added together and mapped to the proper name.

Naturally, I can't guarantee that's exactly how it works, since I haven't seen the source code of the tool, but based on the database structure of MediaWiki, and the PHP source of SpecialContributions.php, that would seem to be the way to do it (or at least, *a* way). --Pidgeot (t) (c) (e) 14:19, 20 September 2005 (UTC)

The website related to the change of atmosphere pressure

Can you give me some website that is related to what will cause the change of atmosphere pressure?

have you looked at the Atmospheric pressure article on wikipedia? Boneyard 11:34, 20 September 2005 (UTC)

ODBC - Pros & Cons

ODBC is a useful technology for allowing a developer to connect to a wide range of databases without needing to alter their applicationcode. But some people have a belief that ODBC is not as good as developing an interface direct to the database's native code. Can anyone list the pros and cons of using ODBC to connect to the database and what pitfalls or advantages their might be in using ODBC?

Welll... I guess the more layers of abstraction the more function calls you must call. Calling on an external library which then calls on a database function takes longer than just directly accessing the database. To be honest though, I think won't cause too much performance problems, and accessing a standardised interface has many more pros than accessing different databases in different ways. - 203.134.166.99 08:11, 20 September 2005 (UTC)

MDAC and ADO.NET

Question: where does ADO.NET sit in the MDAC stack? Do Microsoft consider it part of MDAC at all? The MDAC roadmap does mention it, but doesn't state whether it is part of the .NET framework or whether it is part of the MDAC framework. I know that ADO.NET must use a .NET Managed provider, but these just appear to be a simplified version of an OLE DB provider, even though they don't use COM and instead use the .NET CLR. Can anyone give me an answer to this? I'd like to update the MDAC article. - 203.134.166.99 08:08, 20 September 2005 (UTC)

Answer to my own question: the ADO.Net Managed provider is part of MDAC and part of .NET. - 203.134.166.99 06:47, 27 September 2005 (UTC)

Testing

what is the difference between client server application testing and web application testing?

Web App testing is properly a subset of client-server app testing. However, both are generic enough (and test methods and requirements are flexible enough, depending on particular application), that little more comparison can be made. — Lomn | Talk / RfC 13:13, 20 September 2005 (UTC)

human body

why do we have a running nose when we catch cold?

have you looked at the Common cold article? Boneyard 11:32, 20 September 2005 (UTC)

Gary Killdall

Does anyone know who Gary Killdall was and why he was important to the computing industry ?

Mark Davis

The correct spelling appears to be Gary Kildall (that's the one used by his employer, Digital Research, on their website). That should cover what you're looking for. — Lomn | Talk / RfC 14:38, 20 September 2005 (UTC)

Phosphate rock

By how much will the oceans rise if all the ice melts (assuming the amount of water in the atmosphere stays the same)? A.F. Stewart, Dresden.

Well, according to our article on the West Antarctic Ice Sheet, if it melted completely ocean levels would rise about 5 metres. That is rather unlikely any time soon, even if global warming is real. --Robert Merkel 02:13, 24 September 2005 (UTC)

real estate

What is the name of the person who came up with real estate? — Preceding unsigned comment added by 207.62.88.10 (talk • contribs) 10:46 EDT, 20 September 2005 (UTC)

The concept of real estate, that is land as property, dates back to the start of farming, and there is no record of how the concept was first devised. i doubt that any one person was responsible. See Real estate for much more information. DES ^(talk) 15:55, 20 September 2005 (UTC)

Rocks

What is your questiion about them? DES <sup>(talk) 16:00, 20 September 2005 (UTC)

Rocks rock. — Lomn | Talk / RfC 16:10, 20 September 2005 (UTC)

How igneorant. Rob Church ^{Talk | Desk} 00:09, 21 September 2005 (UTC)

Now, now; be gneiss. TenOfAllTrades(talk)

This is clearly a hard question --jonon 12:24, 23 September 2005 (UTC)

Recusive function

consider a network of streets laid out in a rectangular grid, for example. In a northeast path from one point in the grid to another, one may walk only to the north(up) and to the east(right).How can I Write a C++ program that uses a recursive function to count the number of northeast paths from one point to another in a rectangular grid.

General Idea That I have is that one simply recourses north until one falls off the grid.Recursion automatically takes care of backtracking to a legal grid point & then recursing to the east.

Assuming you can always go north and right at each grid point, the number of paths is equal to ${v-1 \choose v+h-2}$, where h is number of grid points horizontally and v the number of gridpoints vertically. This can be computed using ${n \choose k}={\frac {n!}{k!(n-k)!}}$ or recursivly using Pascal's triangle. --R.Koot 18:03, 20 September 2005 (UTC)

If you can't make that assumption, think about this: the total number of paths that go from your present location to the destination is the sum of a) the number of paths to the destination from the location to your east (if you can go east) and b) the number of paths to the destination from the location to your north (if you can go north). --Robert Merkel 00:40, 21 September 2005 (UTC)

Salt and vinegar

Do salt and vinegar potato chips have any notable health effects? ‣ᓛᖁ♀ᑐ 17:46, 20 September 2005 (UTC)

Well, too much salt is bad for you, they always say. Vinegar I'm not sure about. The crisps themselves may be a problem due to acrylamide content, though I don't think that's settled yet.

Having moved from the UK to the USA, I do miss them. They're much harder to find over here. -- DrBob 18:06, 20 September 2005 (UTC)

Where in the USA? They are practically a staple in the northeast. Yum, --hydnjo talk 18:14, 20 September 2005 (UTC)

The southwest. Nor can you get cheese and onion, prawn cocktail, or smokey bacon crisps for love nor money. Probably because all the hideous chemical flavourings are banned in the US, but still. --DrBob 18:21, 20 September 2005 (UTC)

They can make you fat, of course. More generally, they are very high in carbohydrates, with all their associated troubles. And salt is problematic for some people. But vinegar is generally pretty healthy stuff, so I doubt there would be any health troubles associated with this type of potato chips that wouldn't also be associated with normal potato chips. — Nowhither 18:47, 20 September 2005 (UTC)

• Salt and carbohydrates can both be a good thing when used with caution. Too much of either isn't healthy but too much vitamins isn't healthy either. Salt is useful to keep up the salt content of your body and carbohydrates are good for energy (of course it's no use if you don't use the consumed energy). The brain needs a particular sort of carbohydrate (I think it was sucrose, but I'm not sure), so don't even bother not eating any carbs at all. - Mgm|^(talk) 19:17, 20 September 2005 (UTC)

The flavouring used is sodium acetate, which would seem to be remarkably inocous as artificial flavourings go. My answer would be "no more so than any other crisps (sorry, chips)". Physchim62 14:49, 22 September 2005 (UTC)

Megaparsecs

The furthest quasars detected have been seen to have a distance of 5500 megaparsecs. If a megaparsec approximately equals 3.26 x 10^6 and if the maximum possible distance something can be detected away from us is 13.7 billion light years away which equals around 4202 megaparsecs much less than the distance from the furthest away quasar how is it possible to detect a quasar when light hasn't had enough time since the beggining of the universe to reach us?--Mr A Pinder 21:45, 20 September 2005 (UTC)

Without extensive research on my part, most likely because 13.7 bn ly is no longer the detection limit. Astronomers observing a new oldest-thing-ever is fairly common. — Lomn | Talk / RfC 20:08, 20 September 2005 (UTC)

That doesn't seem to explain anything though. How is 13.7bn ly no longer the limit, did we increase the speed of light? Go forward in-time? The only assumption I can make is that the object in question (a quasar with 5500 megaparsecs distance) was in fact within the 13.7 bn ly distance when the light first got here using it's redshift the actual distance was calculated. That's the only explanation I can think of though. --82.7.209.62 11:39, 21 September 2005 (UTC)

The exact age of the universe isn't known. As scientists learn more (by finding new quasars for example) the numbers get revised. I think that is all that is happening here. Theresa Knott (a tenth stroke) 22:23, 21 September 2005 (UTC)

March 2005 Sciam article "Misconceptions about the Big Bang". Whole article is interesting, but in case the link doesn't work, the relevant part:

If space were not expanding, the most distant object we could see would now be about 14 billion light-years away from us, the distance light could have traveled in the 14 billion years since the big bang. But because the universe is expanding, the space traversed by a photon expands behind it during the voyage. Consequently, the current distance to the most distant object we can see is about three times farther, or 46 billion light-years. Frencheigh 22:44, 21 September 2005 (UTC)

Eyelashes

Many hairs on the human body appear to initially grow in a locally prefered direction, but curly hairs generally seem to curl in random directions. Eyelashes on the other hand are highly ordered and align in their direction of curling. Is there an interesting story as to how this happens? -- Solipsist 19:41, 20 September 2005 (UTC)

Wisteria trees

How can you tell a male from a female wisteria tree?

Trees, being a form of plant, have both genders; their flowers have both stamens and stigmae. Rob Church ^{Talk | Desk} 00:11, 21 September 2005 (UTC)

The situation described in plant sexuality is rather more complex and certainly allows for the possibility of separate male and female plants, at least for some species. As for wisterias, I would have no idea, but to wait for beans. — Pekinensis 23:19, 21 September 2005 (UTC)

I just checked with an expert -- my local Master Gardner helpline. I was told that Wisterias have "perfect form" i.e. they have both male and female parts on all trees. not all trees have this property, but it seems that wisterias do. DES ^(talk) 20:48, 22 September 2005 (UTC)

Methadone clinics

How many methadone clinics are there both public and private in the United States?

Jim

ethernet

Do you have a question about ethernet? AlMac|^(talk) 20:22, 20 September 2005 (UTC)

How to build a TV station

I am interested in building educational TV Station in Afghanistan. From the technical point of view what kinds of equpments I need.

• What types of cameras do I need.
• What types of camera and equpments are required inside the TV Station.
• What types of equpments I need to broadcast. (The type of equpments and
• How far they could reach.)

Unfortunately, I think this topic is far too complex to give a useful answer in a paragraph or two. You will need quite a lot of equipment and a considerable amount of expertise to set up your station, and the necessary equipment will cost lot of money, even if you buy it second-hand. To figure out what you require, you will need to consult extensively with an expert, or spend some time working with TV people yourself to learn what's required (Foriegn press reports have mentioned that there is a TV station in Kabul, for instance).

If I were you, I'd also go and speak to some of the foriegn aid agencies working in Afghanistan. Not only could they put you in touch with people who have the expertise you need, they may be able to help out with sourcing of the right equipment.

In terms of the transmission range, if you use terrestrial TV transmission it will basically be line of sight. Any mountains between your transmitter and the recipients will mean they won't be able to see your signal. So if you want good reception range make sure your transmitter is at the top of a mountain to maximise the area that it can be viewed from!

Good luck with your project, which sounds very admirable. I wish I could be more helpful. --Robert Merkel 00:20, 21 September 2005 (UTC)

I am no expert on this either. Perhaps the organizations helping the rebuilding effort can put you in touch with relevant experts in their home nations. You'll need transmitting of a kind that will match the reception for your audience.

There are also international organizations that help developing nations in general with such things. Sometimes it is more economical to use satelite dishes in remote villages. An advantage of this is that they can access educational TV from many nations, not just what you are putting out.

• for example Trinet is a European effort, mainly in Africa to aid developing nations inexpensive communications. This Trinet link also has info about a discussion group precisely to help people in developing nations get at resources for projects such as yours.

AlMac|^(talk) 00:25, 21 September 2005 (UTC)

One more thing to consider; community television organizations run on very low budgets, often with volunteer staff, so they know a thing or two about running a minimalist TV station. It's another area to look into which might provide some helpful contacts. --Robert Merkel 06:02, 21 September 2005 (UTC)

Also many public television stations in the USA that deliver via cable television, they are able to have several cable channels, at least one devoted to public interest topics, in which the general public is invited to attend classes in how to operate the cameras, can rent them (leave a deposit sufficient for insurance), to do community coverage of general interest.

You might also check with the Universities of Journalism around the world. Some of them have their students publish inexpensive newsletters, with faculty advisors. This might help you see what is the state of art in other nations, expectations of journalism excellence standards.

Columbia School of Journalism publishes CJR Columbia Journalism Review

I tinkered slightly with your question above to make it more obvious what you asking about, because my areas of know-how not quite on point with what you need.

AlMac|^(talk) 07:12, 21 September 2005 (UTC)

A Variable Speed of Light

The particle theory of light states that the main particle in light is a photon and it has been proven that photons of light must have a mass (even if extremely low) because they cannot escape a black hole. If, theoretically, you shone light directly into a blackhole this would certainly speed up the light photons as by Newton's law; acceleration = mass x force. Therefore how is it that the speed of light is thought of as a constant?

Furthermore in the special theory of relativity as you get close to the speed of light, time itself slows down until it comes to a stand still at the speed of light. If light was to go faster than the speed of light (assuming the 'speed of light' is the speed of light throughout space) then wouldn't that mean the light entering a blackhole was going back in time?

Photons do not have mass, not even an extremely low one. They are affected by gravity because gravity warps the entire spacetime. However, although photons are massless, they do have momentum, and this value describes their behavior when influenced by gravity. Note though that Newton's laws don't hold for these calculations; we must use general relativity instead. In particular, it is wrong that acceleration = mass × force. This is only true for very small speeds; when the speed begins to approach the speed of light, infinitely much more energy is needed to accelerate further. Only massless particles can travel at the speed of light. See the articles on photons, the speed of light, and the theory of relativity for more information. Fredrik | talk 20:56, 20 September 2005 (UTC)

Well, of course it's wrong that "acceleration = mass × force". However, it's at least approximately correct that force = mass × acceleration. And that is the usual modern statement of Newton's Second Law. However, what Newton actually said was that force = d(momentum)/d(time). And that is exactly right. Even for light. — Nowhither 23:14, 20 September 2005 (UTC)

I can't believe I missed that one... - Fredrik | talk 10:50, 21 September 2005 (UTC)

The speed of light is based upon the medium it travels through. Light travels faster through space than through the atmosphere, and faster through air than glass. Physics demands than when a particle falls toward a black hole it has to gain energy. Particles with mass go faster to do this, massless particles instead gain energy, so you see a blue-shift as the photon's frequency increases.

Many thanks for the answer i've always thought particles affected by space-time must have a mass but of course they only have to be affected by space-time e.g everything. --Mr A Pinder 21:44, 20 September 2005 (UTC)

This touches on something I've been wondering about concerning black holes. As I understand it, all the strange effects one sees when something enters a black hole only really hold from the perspective of an outside observer, but for something (someone?) entering the black hole everything is 'as normal' (ie the normal laws of physics still hold from that perspective?). So is it that the light really doesn't change frequency but it only appears so for the 'outsider' who sees the distortion of space/time (which the 'insider' doesn't)? DirkvdM 12:34, 21 September 2005 (UTC)

Good question. But you have it backwards. The outsider would not see light approaching a black hole, but light which is moving away from a black hole would be red shifted. It is not possible for light to escape a black hole, but a light emitting object moving close to a black hole, or any superdense body, would show a red shift. An observer would need to be between the black hole and the light emitting object to see a blue shift. As far as whether the light 'really' changes frequency, that is a difficult question, almost in the realm of metaphysical debate. Physics says the light would have to gain energy to move into a gravitational well, and the only way to do that is to increase frequency. If that is due to a space distortion, well maybe so.

I was thinking theoretically, not empirically. Of course you can't 'see' a photon moving towards a black hole because it would have to 'emit something' we can detect. But indeed without the possibility of empirical testing it's little more than metaphysics. But isn't much of modern day physics then not really metaphysics? I anticipate two possible reactions to this. One is irritation (suggesting I'm on to something). The other is that I've just exposed myself as the layman (read 'philosopher') I am :) . DirkvdM 06:58, 23 September 2005 (UTC)

By the way, there is an interesting and somewhat related issue here that no one has brought up. Yes, the speed of light varies depending on the medium it is passing through. When we say "nothing can go faster than the speed of light" we really mean "the speed of light in a vacuum". That means that if we are not in a vacuum, then it is theoretically possible for an object to go faster than light.

This has interesting implications. What happens when an object in the air goes faster than sound? Answer: a shockwave, whose sound is often called a "sonic boom". An object traveling faster than the speed of light in some medium can produce similar electromagnetic shockwaves. These go by the name "Cherenkov radiation". For more information, refer to that article.

— Nowhither 23:35, 21 September 2005 (UTC)

Bacteria

What are the differences of Gram-positive and Gram-negative bacteria?

See our articles on Gram-positive and Gram-negative. Chuck 21:58, 20 September 2005 (UTC)

tadpoles

how do tadpoles get to be full breed forgs i mean how does the process work?

As you might expect, it's a very complex process, and there's no quick answer to the question. Research into questions like that is a very active part of cutting-edge research in biology (which is another way to say "there's a lot we still don't know"). That area of biology is called developmental biology, and the article I've linked to might be a good starting point. Chuck 23:02, 20 September 2005 (UTC)

"Find the zeros of each function"

How do I solve problems that ask "find the zeros of each function" and give an (f)x equation, such as:

f(x) = 3x - 8

f(x) = (x/2) + 5

f(x) = 19

--69.163.150.70 00:18, 21 September 2005 (UTC)

If you want to find the zeroes of a function, you should replace the f(x) with 0 and solve the resulting equation, for instance, the first one will become

$3x-8=0$

If you need help solving equations like that, might I suggest you have a look at Doctor Math and his very extensive explanation of problems like these? --Robert Merkel 00:32, 21 September 2005 (UTC)

In the first two examples you provide, there is only one zero per function. As you can see from your third example, it is not always possible to find any zeros of a function:

$f(x)=19$ (replacing $f(x)$ with 0 results in a falsehood ($0=19$))

The other two require a little algebra:

$0=3x-8$

$8=3x$ Add 8 to each side.

$8/3=x$ Divide each side by 3

There is one zero: When $x=8/3$

$0=(x/2)+5$

$-5=x/2$ Subtract 5 from each side

$-10=x$ Multiply each side by 2

graph theory

what is a weakly connected dominating set?

See Glossary of graph theory. Chuck 04:05, 21 September 2005 (UTC)

Volcanoes and the hydrosphere(seawater, and underwater volcanoes)

1. ) How do volcanoes at mid-ocean ridges affect the temperature of seawater?
2. )How do volcanoes change the chemistry of seawater?
3. )How does seawater affect the composition of the volcanic rock that is formed at the mid-ocean ridge?
4. )Would volcanoes affect a small body of seawater, such as the Red Sea, the same way as a large ocean like the Atlantic?
5. )Can a change in the volume of volcanic rock formed at mi-ocean ridges change sea level?

I tinkered with your question just a little bit to make it easier to see what your questions are. I am not an expert at this, and I am a novice at using reference works, but hope what little I know can help you navigate what is here. I looked at several articles here, such as Volcanology and concluded that there is a lot of room here for upgrading the content of these articles, given recent news such as the 2004 Indian Ocean earthquake disaster.

1. Do you suppose there might be an article on volcano in this on-line encyclopaedia?
   1. Yes, and how about Submarine volcanos on the ocean floor? However, seems to me it is somewhat of a stub article that does not go into much detail on your questions of the chemistry of lava in sea water.
      1. Bogoslof Island is the summit of a mainly underwater stratovolcano in the Bering Sea, 31 miles from the main Aleutian volcanic arc (That's off Alaska USA).
      2. There are several parts of Hawaii that came from the sea, thanks to volcanic eruption, that started totally underwater, such as Loihi Seamount.
      3. Monowai Seamount is another, in the vicinity of New Zealand. It is still totally below sea level.
   2. The Wiki article on Hydrosphere is also a stub so we may have to go outside Wiki to get you a good answer.
2. You might find some info of relevance in the Wiki articles on geology, hydrogeology and other effects of underwater volcanoes, such as tsunami (giant tidal waves).

AlMac|^(talk) 04:15, 21 September 2005 (UTC)

computer networking

list five different network devices

Another case of "Do your own homework", but because it's so simple: Network Interface Card, Hub, Switch, Bridge, Router. Thank you, thank you, I'm here all week. Try the veal.--inks 03:23, 21 September 2005 (UTC)

You missed "wire" :-) Veal's off Tonywalton  | Talk 22:06, 21 September 2005 (UTC)

A telephone is a network device.

A fax machine

Their value is related to how many others of the same kind of device they can talk to.

Is a "wire" a "device"? AlMac|^(talk) 07:25, 22 September 2005 (UTC)

Does hot or cold water freeze faster?

I have heard many arguments for the question, does hot water or cold water freeze faster, and was wondering if someone could fully answer this for me, and explain why there is such a debate on this question. --confused

See Mpemba effect. ‣ᓛᖁ♀ᑐ 03:46, 21 September 2005 (UTC)

Amazing! And puzzling. My first reaction was that the warmer water (or whatever) would have to cool down to the temperature of the cooler water, from which point the situation is equal for both, so the warm water should always take longer to freeze. But as I understand the article (which I don't entirely :) ), the difference is not so much the present temperature but the fact that the liquid has been warmer. In other words, if two vessels of water have previously had a higher temperature and one is given a headstart by letting it cool down a bit before the 'contest' then it will 'win'. Right? DirkvdM 12:48, 21 September 2005 (UTC)

My understanding is hot water, due to the heat driving out dissolved gas, will freeze faster.

Which fits in with what I said. The difference then lies in the fact that the water was previously heated. Not in the actual temperature. DirkvdM 07:57, 22 September 2005 (UTC)

More info from the Straight Dope. - Bloodshedder 03:00, 23 September 2005 (UTC)

how many light years is in a minute

Your question, as written, makes no sense. A light year is a measure of distance; it is how far light travels through vacuum in a year. A minute is a measure of time. People occasionally use the term "light minute" and "light second", as described in the light year article. --Robert Merkel 05:44, 21 September 2005 (UTC)

A light minute is 11160000 miles or 186000 * 60.

Don't forget that the Millenium Falcon made the Kessel run in less than 12 parsecs. :-) — Nowhither 23:55, 21 September 2005 (UTC)

how many miles does the earth travel around the sun?

The Earth article lists the details of the Earth's orbit; the orbital circumference is 0.940 Terametres, which is another way of say 940 million kilometres. --Robert Merkel 05:50, 21 September 2005 (UTC)

Water Weight

Is hot water heavier than cold water?

Generally not. Our article on water says that "Fresh water has its greatest density at 4°C. It becomes less dense as it freezes or heats up." --Robert Merkel 05:52, 21 September 2005 (UTC)

However, if we take your question literally, from my limited understanding of special relativity the same number of molecules of hot water will be ever so slightly heavier than the same number of molecules of cold water. According to special relativity, the rest energy of an object is directly proportional to its mass. The rest energy of the hot water is greater than the cold water. Therefore, it must have greater mass. In practice, this effect will be almost undetectable, though, because the amount of energy "contained" in a mass that the extra energy from a little bit of heat is a tiny fraction of the object's total energy. However, we usually don't count molecules to measure quantities of water, we measure volume. --Robert Merkel 05:59, 21 September 2005 (UTC)

It depends how much of each you have. A litre of hot water is a lot lighter than a swimming pool full of cold. for example. Tonywalton  | Talk 22:08, 21 September 2005 (UTC)

elevators

(no question)

• They're usually used to get up and down in building without the use of stairs. See elevator. - Mgm|^(talk) 10:28, 21 September 2005 (UTC)
• They are also aircraft control surfaces and grain storage facilities, among other things. See elevator (disambiguation). — Lomn | Talk / RfC 13:22, 21 September 2005 (UTC)

achievements of world nations in remote sensing technology

(no question asked)

Did you have a question? You could try the Wikipedia remote sensing article. Or you could post again and ask a question. — Nowhither 01:01, 23 September 2005 (UTC)

Yellow bell

What is the phylum or division name of a Yellow bell?

Magnoliophyta. See the article Allamanda. ("Yellow bell" should also take you there now that I have created a redirect page.) - Fredrik | talk 11:16, 21 September 2005 (UTC)

Electricity

What is static electricity?

Does the article, static electricity, explain it for you? - Fredrik | talk 11:08, 21 September 2005 (UTC)

Browser IDs

How can I change the user id string of Mozilla Firefox without using an extension? --anon

You go about it in the about:config menu (accessed via the address bar), full instructions available here [1] — Lomn | Talk / RfC 13:19, 21 September 2005 (UTC)

Circulatory system

Are there any really interesting facts about the circulatory system? It's for a project about the human body that I am making here.

I would suggest poking through our article circulatory system to see if anything jumps out at you. Some of the historical ideas about circulation are quite interesting. The articles linked in Template:Cardiovascular system are also quite extensive. You'll have to judge for yourself what counts as 'really interesting'. TenOfAllTrades(talk) 17:53, 21 September 2005 (UTC)

WinZip

Can someone point me to the latest fully functional (not a trial version or security patch) of WinZip. Somehow, this particular system I'm working on hasn't got one installed... :( - 82.172.23.66 18:06, 21 September 2005 (UTC)

The free (trial) version at winzip.com is functionally the same as the full version. — Lomn | Talk / RfC 18:49, 21 September 2005 (UTC)

• I know, but I'd prefer a version that lasts beyond a 21-day trial. - Mgm|^(talk) 21:13, 21 September 2005 (UTC)

There's no actual limit on its usage (at least not with older versions, not sure about 9.0), you just have to live with the nag message.

Failing that, there are plenty of free alternatives. 7-Zip is a free archiver with support for many formats, including (as you might guess) the .7z format, which tends to offer much better compression ratios than ZIP. --Pidgeot (t) (c) (e) 22:03, 21 September 2005 (UTC)

• Original poster: The way you get the non-nagging version of WinZip is to get the trial version, and, when it nags you, click the button to pay for it. It seem to remember the button is labeled "Buy Now". In any case, you can't miss it. — Nowhither 01:04, 23 September 2005 (UTC)

Bipolar Medically speaking.

Would it be safe to say that those who've listened to D.Leppard and Queen and Pink Floyd would be considered having a trait of Bipolar tendisies??? How often should these tendicies be seen??Why isn't the Bipolar medication today worth taking without side effects??? Shouldn't doctors use herbs and other natural substances instead??? why make things worse?? thanks for seeing my email

christie lofton, christielofton@hidden.com

I've obscured your email address, as it's probably a bad idea to leave it out in the open for spam harvesting. Anyway, to attempt to answer:

1. No. Debatable taste in music is not a medical condition.
2. Bipolar tendancies vary by individual.
3. Most medicines have side effects in one form or another. Generally, as a drug type remains on the market, continuing research reduces side effects.
4. That depends primarily (in my personal opinion, I would hope completely) on the established effectiveness of such remedies.

Hope this helps. — Lomn | Talk / RfC 18:45, 21 September 2005 (UTC)

You could try reading An Unquiet Mind by Kay Redfield Jamison, Published: Picador (UK) ISBN 0330346512 Vintage (US) ISBN 0679763309. Jamison is a practising psychiatrist and a sufferer from severe bipolar disorder; the book's a good insight into the disorder itself, the effects it has, and into its treatment. She omits to mention any general connection with musical taste, though. Tonywalton  | Talk 22:19, 21 September 2005 (UTC)

People who listen to the dull cock rock of Def Leppard are far too mentally stilted to exhibit the outre signifiers of bipolar disorder. Similarly Queen appeals to the unsophisticated good time sensibility that may engage a bipolar person in an up phase but lacks (Bohemian Rhapsody excepted) the poetic spirit we romantically like to think as being part and parcel of tragic melancholy. Once Syd Barrett left, Pink Floyd appealed only to architects. This answer may be deemed controversial by other wikipedians, but I wouldn't listen to anyone else. Stick with me: I know what I'm talking about. --bodnotbod 15:11, 22 September 2005 (UTC)

Oh, I don't know. Who wants to live forever is pretty much down-phase. Tonywalton  | Talk 23:38, 24 September 2005 (UTC)

Shock horror! Pink Floyd produced some of the definite progressive rock of our times. So there. Yeah, you've been told. :P Rob Church ^{Talk | Desk} 21:00, 25 September 2005 (UTC)

what hypothesis did beadle and tatum test in their experiments on neurospora

Typing neurospora into the search box on the left will allow you to find articles which will probably help you to do your homework. In future, please refer to the instructions at the top of the page and note that Wikipedia isn't here to do your homework for you. TenOfAllTrades(talk) 18:56, 21 September 2005 (UTC)

Latest technology

What are some of the latest technologies available in the classroom and/or to teachers/students?

We already know someof the things available, but what are the newest forms of technologies to aid in education and learning?

Are there any "cutting edge" ideas, computers, computer applications, websites, downloads, etc... that can help teachers and education majors to integrate technology into their classrooms?

If possible, could you please email a response to Susan Wurth at Kaskaskia College(Re: Crystal's Question for EDUC 116)? Her email address is <REMOVED> Thank you!

Well interactive whiteboards are gaining in popularity. Theresa Knott (a tenth stroke) 20:13, 21 September 2005 (UTC)

To the original poster: You have hit on a topic that Wikipedia does not cover very well. We have an article on Educational technology, but it is a lousy article. Perhaps I'll go clean it up. Or you can, if you want. Meanwhile, there is plenty on the web. See, for example, the "Encyclopedia of Educational Technology" at http://coe.sdsu.edu/eet/ . And here is a blog about the topic: http://people.uis.edu/rschr1/et/blogger.html . Also, I have removed Susan's e-mail address, so that every spammer in the world doesn't start deluging her with nonsense. May I suggest that you do not post e-mail addresses (especially if they belong to other people??) in a public forum. — Nowhither 00:27, 22 September 2005 (UTC)

Educators are learning how to use the power of the Internet to help them network with each other and do their job more effectively.

• There are discussion groups for particular kinds of teachers, school librarians, etc.
• Homework Hotline is a deal where a student having trouble with subject X, phones the service and ends up speaking with a teacher of subject X at the student's grade or age level, but who is at some different school system ... different city, public parochial, whatever. Result is the student gets immediate help, and the teachers record the kinds of questions that re-occur so they can improve the curriculum.
• Parents can go to a web site, select which school, grade level, subject, to see what the homework assignments were.
• There's article in today's USA Today Newspaper about mental health professionals watching pre-schoolers to catch those that have disabilities that can be helped early.

AlMac|^(talk) 07:32, 22 September 2005 (UTC)

Here's an interesting way to use the Internet for educational purposes. Give students the task of adding to a Wikipedia article. That would be less boring to the student, they have to research a subject for themselves, interpreting and rewording the findings, in stead of just memorising what some textbook says (a direction society is going in I'd say) and it will give them more satisfaction because they actually do useful work (for all the world to see!). I suppose this means more work for the teacher, who has to read through the edits, but it would certainly be less boring for them too. DirkvdM 08:07, 22 September 2005 (UTC)

An interesting idea indeed, but please can the teacher him or herself first research the Wikipedia criteria and impress them on the students before they start? Quite a few establishments do do this (or say "contribute an article" rather than "add to an article") , but sadly it can end up with a number of two line articles on things like "My school dining room" or "Mr Hockenheimer my Teacher, which are deleted, sometimes speedily, which must be a bit discouraging for the students who have contributed them in good faith. Tonywalton  | Talk 23:49, 24 September 2005 (UTC)

cost of touch screen feature

Why do Tablet PCs cost much more than laptops. Are they costly because they have touch screens and pen? How much does it cost to add a touch screen to a device? Or simply, how much does the touch screen facility alone would cost? --Tom

Touch screens are indeed very expensive (1.5-4x price?) compared to normal LCD screens, but any prices that I might be able to quote for desktop monitors won't be relevant to laptops. I imagine the small market for tablet PCs compared to the much larger market for laptops has an effect on price too. Interestingly, touchscreen LCDs seem to need constant (sometimes daily) recalibration -- do tablet PCs suffer the same problem? Ojw 20:34, 21 September 2005 (UTC)

I'd hazard that prices are also slightly higher to help Microsoft recoup OS development costs since they're not able to sell retail or upgrade versions of XP Tablet Edition. Re: Ojw, mine only needs recalibration when I flip between landscape and portrait mode, owing to the reorientation of my hand when near the screen edges. — Lomn | Talk / RfC 21:15, 21 September 2005 (UTC)

what trees do acorns come from

Oak trees (see acorn). — Lomn | Talk / RfC 20:09, 21 September 2005 (UTC)

History of Science examples from Kuhn's SSR

Hi all - I am putting together a website for a class taught by the department of Logic and Philosophy of Science at UC Irvine. Among other things, the students will be reading Thomas Kuhn's The Structure of Scientific Revolutions. For those of you who haven't read it, it is packed with history of science examples that are, to put it bluntly, never explained. Since the students will mostly be sophomores in college, I am endeavoring to put together a glossary of Kuhn's examples. This glossary has a few sentences on each examples, and links to Wikipedia for a more detailed description. Unfortunately, I have been unable to track down many of these examples, and so I'm turning to you for help! Anything you know about any of these examples would be a great help. If this stuff is somewhere on wikipedia, please tell me where so that in composing my entry I can link there. Here are the examples I cannot locate:

• Some method for measuring electrical attraction using a pan balance (I have an idea how this would go, but I'd like to know who did this and to what use it was put)
• Some problem in applying Newton's laws to the moon, and the solution proposed by Alexis Clairault.
• He makes a reference to the "Pneumatic Chemists"
• Kepler and the motion of mars
• "The proliferation of gases" surrounding Priestly. That's really all he says.
• The effluvium theory (some theory of electricity)
• Hauksbee's apparatus (something to do with electrostatic repulsion)
• Musschenbroek and his observations regarding a charge filled bottle (I assume this is a leyden jar)
• The theory of elective affinity (some chemical theory that had to do with acids, I think)
• Rayleigh's paradoxes of electrodynamics (I don't think this is supposed to be Rayleigh scattering)
• Kepler's Rudolphine tables. (I assume this is the Tabulae Rudolphinae mentioned in the article, but I don't know what the tables are for)
• Poisson and the a "reductio" of the wave theory of light (this refers to the prediction of a bright spot at the center of a shadow, which was latter observed by Fresnel. Do have anything on this anywhere?)

• The Joule-Lenz law H=RI^3 (does this go by a different name now? I can't find it under that name)
• Do we really not have an article on Christian Huyghens? (okay, maybe this is just rhetorical)

Phew... that's a lot, I know. Believe me its only a small number of the total examples. Anything at all would be incredibly helpful! Thanks a million! --best, kevin ···Kzollman | Talk··· 21:22, 21 September 2005 (UTC)

• Did you mean this Christiaan_Huygens?
• Effluvium: According to [2] it has something to do with William Gilbert. --R.Koot 21:33, 21 September 2005 (UTC)

No... I meant the mispelled one. *bows head in shame* In my defense (and I double checked) Kuhn refers to him as "Huyghens" and there are websites using that spelling. I've created redirects. Thanks, I'll see if I can find something on effluvium. --best, kevin ···Kzollman | Talk··· 22:40, 21 September 2005 (UTC)

• Joseph Priestley did indeed have a grand proliferation of gases - he identified eight, according to our article, when "air" was previously thought to be the only one to exist. He was a co-discoverer of oxygen, among others. I believe there's a recent biography of him; skimming that might be useful since our article is pretty sparse. Shimgray 22:43, 21 September 2005 (UTC)

Yeah, the case for oxygen is hard, since he called it "dephlogisticated air", right? Anyway, Kuhn says that the proliferation of gases was considered a problem in Priestley's day, any idea why? Kuhn seems to say even Priestley thought this was a problem. --best, kevin ···Kzollman | Talk··· 22:48, 21 September 2005 (UTC)

• for the motion of mars see Kepler#Kepler's_laws. In short, Kepler was trying to reduce complex and error-fileld observatrional data to simple laws of motion. Mars presents a particualrly tricky case, becasuse its orbit is outside earth's orbit, which as earth overtakes mars leads to apparent "retrograde motion". the diagram at the above link shows a simple version of this, but a good bio of Kepler is probaly worth finding and skimming as our article is a bit brief here. DES ^(talk) 22:57, 21 September 2005 (UTC)

• for Hauksbee see Barometric light and this site as a starting point. DES ^(talk) 23:03, 21 September 2005 (UTC)
  • I just created Francis Hauksbee which may also be useful. DES ^(talk) 00:06, 22 September 2005 (UTC)
• This link is an article on Khun that may be helpful. DES ^(talk) 23:18, 21 September 2005 (UTC)

Great! Thanks, that article will be a lot of help! --best, kevin ···Kzollman | Talk··· 00:43, 22 September 2005 (UTC)

• For Rayleigh, probably refers to the Rayleigh-Jeans law and the ultraviolet catastrophe (which led, eventually, to QM).

Poisson's spot: Poisson thought he'd killed Fresnel's wave theory of light (which he was a big critic of) by showing that it predicted a (seemingly absurd) spot of light that should be visible at the centre of a circular shadow. However, François Arago experimentally found the spot almost immediately. A Fresnel zone plate is essentially an expansion of this idea. -- DrBob 01:15, 22 September 2005 (UTC)

• More: The Joule-Lenz law is also just called Joule's law.

• I'd just point out that most of Wikipedia's articles on scientists and history of science are unfortunately not very informed by critical historical literature, and are instead what Kuhn calls "textbook science" in the introduction to SSR. So beware in using it for your examples! The best book (quick, straightforward, and accurate) for anything relating to early modern physics or astronomy is J.L. Heilbron's Elements of Early Modern Physics which the Irvine library probably has a copy of, if you are still stumped after all of this. (Heilbron, incidently, was Kuhn's research assistant while he was writing SSR; now he's the grand old man of history of physics, but still very active) --Fastfission 02:56, 22 September 2005 (UTC)

How weight system originated?

How weight system originated?

e.g 1Kg., How first unit of Kg. came in to existance?

Axay

Axay,

Our Units of measurement article has a good section on the history of various forms of weights and measures including the SI or metric system. You may also wish to check out the U.S. customary units for the history of the imperial system now used mainly the US. Capitalistroadster 01:09, 22 September 2005 (UTC)

Project 1947

What was Project 1947? Has to do with UFO's in Bayreuth, Germany in 1947.

It appears that Project 1947 was an effort beginning in the 1990's by UFO enthusiasts/researchers, to examine lots of local newspapers from a period in which UFOs were reported to be observed. If the page isn't working for you, try this page from the Google Cache. One of the links is to a page selling copies of their preliminary report. --Robert Merkel 02:46, 22 September 2005 (UTC)

remembering amino acids

Are there useful mnemonics, rules, shortcuts et cetera, to help one remember all 20 common amino acids, whether they're polar, nonpolar, acidic or basic, that sort of thing? --Miborovsky 01:45, 22 September 2005 (UTC)

• Well, I found this for the names: http://wwwchem.csustan.edu/chem4400/code.htm --jpgordon∇∆∇∆ 02:40, 22 September 2005 (UTC)

astronomy

what is our comic address in order of increasing size? Where is the Sun in the Milky Way?

• The sun is located on the outer edge of the milky way, roughly 28,000 lightyears from the galactic center.
• In addition: We know that the Sun is on the edge of what is probably a 'spur' called the Orion Spur which seems to merge with the Perseus Spiral arm towards the constellation Cygnus. The Perseus Arm is the one just outward from the Sun's location in the Galaxy about 700 to 1000 parsecs from us. Beyond the Perseus Arm, there may be a more distant one, but the arms become less distinct in the outer galaxy zone. from [3]
• I don't quite understand the first part of your question. Please elaborate. - Cobra Ky (talk, contribs) 04:33, 22 September 2005 (UTC)

I believe the OP meant cosmic address in increasing size. So, for me, Fukiage district, Chikusa ward, Nagoya city, Aichi prefecture, Honshu island, Japan, Asia, Earth, the Solar System, then apparently the Orion Spur, the Perseus Spiral arm, the Milky Way galaxy, then…? Garrett Albright 04:53, 22 September 2005 (UTC)

Then the Local Group, Virgo Supercluster, etc... peruse the large-scale structure of the cosmos for more. — Lomn | Talk / RfC 04:55, 22 September 2005 (UTC)

Saying that we live near The Sun in the Local Group is a bit like writing "My house/My Street/My Town" as an address. Unfortunately, we don't know anyone who lives elsewhere to standardise our addresses with... Ojw 11:23, 22 September 2005 (UTC)

We live on a blue-green planet that orbits an unregarded yellow star far out in the uncharted backwaters of the unfashionable Western spiral arm of the galaxy...Brian Schlosser42 20:22, 26 September 2005 (UTC)

Cyclones v's Hurricanes

Could someone explain the difference between a Cyclone and a Hurricane?

Thanks.

A

It's solely where they form, see tropical cyclone for cyclones, typhoons, and hurricanes. — Lomn | Talk / RfC 04:53, 22 September 2005 (UTC)

Diesel Engine

It is practically difficult to obtain more than 2500 rpm in a 4-stroke diesel engine. Why?

This is a good question, and it's not actually covered by the diesel engine article. According to this page on the Perkins diesel corporate site it seems it's because it's more difficult to get the fuel-air mix into the cylinder in the right quantities and distribution for combustion than in a petrol engine, though the limiting factor is different for large diesels than small ones. Note that modern automotive diesels can generally do up to about 4500 rpm, and the very latest diesels (for instance, one in the upcoming Mercedes-Benz S-class) can do up to about 5000. --Robert Merkel 06:17, 22 September 2005 (UTC)

My explaination is due to the compression ratio in a diesel the engine components need to be more robust than those in a gasoline engine and so are more massive. Also, I think diesel burns more slowly so it is harder to get more engine RPM.

Water

why is water clear

• Our Water article is quite detailed but doesn't explain this. However, this article seeks to explain the colour of liquid water [4]. Capitalistroadster 06:53, 22 September 2005 (UTC)

Aluminium dross.

Aluminium Dross is a mass of solid impurities floating on a molten aluminium bath. It is caused due to oxidation of the metal. It can easily be skimmed off the surface before pouring the metal into a mold. What are the constituents of Aluminium dross ?

Ranjan

• I would say that the result of oxidising aluminium in air would be primarily aluminium oxide, but I'm not a chemist. Bovlb 07:12, 22 September 2005 (UTC)
• I am and I don't see any reason to disagree with you if aluminium gets oxidized you get aluminium oxide. - 131.211.210.12 07:44, 22 September 2005 (UTC)
• If the dross is formed during the extraction of aluminium, it is quite impure, with significant amounts of magnesium and silicon oxides. If it is formed on the surface of pure molten aluminium, it should be pretty pure aluminium oxide. Physchim62 14:20, 23 September 2005 (UTC)

whom should we pay to register a domain

Why should we pay for registering a domain? To whom does that money go? For example, yahoo provides that service for $4.99. If possible, tell me How much does yahoo take in that and who takes the rest?

Because somebody has to maintain the root servers for the Domain name system, and that costs money. Yahoo's margins on its business is almost certainly a secret, but given the number of companies offering an identical service it's likely to not be very big. Ah, the wonders of the free market. Shop around and find the cheapest price! ---Robert Merkel 07:29, 22 September 2005 (UTC)

More specifically, a handful of companies are taking millions of pounds per year to run the DNS services that used to be done by one person (Jon Postel?) on his spare PC. See Verisign, ICANN and IANA for some of the companies involved, and a bit more about where the money goes. Ojw 11:19, 22 September 2005 (UTC)

Pioneers of Adsense

Google has a program called Adsense in which they place text ads on other sites. Did they pioneer this idea? or did someone else pioneer this concept? I would also be interested in knowing who pioneered Adwords first. Was it overture?

• The concept of search based advertising was originally developed by Goto.com then Overture who became Yahoo! Search Marketing when acquired by Yahoo!. Google developed similar programs in 2000 as AdSense and AdWords. Capitalistroadster 07:22, 22 September 2005 (UTC)

Msn TV / WEB TV and mouse

Why does a MSN TV or WEB TV does not have a mouse? Are TVs not cabable of supporting mouse OR is it for some other reason?

In the early days of computing, we used a TV instead of the modern day computer monitor. Since then, both the standard digital devices and the analog TV have evolved dramatically, and the analog TV is being replaced by a digital TV. I have a hard time believing the mouse cannot be supported, since I used it on a variety of standard and non-standard screens of PCs and Ncs, so I figure the reason has got to be related to what they are marketing, and possibly not want to spend much money on tech support for different customers with different kinds of home devices. AlMac|^(talk) 07:41, 22 September 2005 (UTC)

Essentially, a Web TV is a small computer running special software that uses the TV for display and has an internet connection of some kind. Making a computer work with a mouse is a fairly trivial task which can be done for just about *any* computer and could certainly have been done for the little computer in the WebTV box. The reason why they didn't is probably because they thought that the users of WebTV would be sitting on the couch, and therefore the flat surface you need to operate the mouse would not be available. --Robert Merkel 07:39, 22 September 2005 (UTC)

What cause low pressure and high pressure at an area?

Can you tell me how the atmosphere pressure change at an area?What would probably cause the atmosphere pressure of an area change?Does the sunlight play the important role on it?Or else?

• See Atmospheric pressure: "Atmospheric pressure is the pressure above any area in the Earth's atmosphere caused by the weight of air." If the sun gets through that's probably because there's less clouds to obstruct its view (which would have an effect on pressure. That's why barometers are used to predict weather. But the sun does not have a direct influence. - 131.211.210.12 07:48, 22 September 2005 (UTC)

Density of Water

Why is the density of water 1 gm/cm^3? I have been under the impression that either the gram or the meter (I don't remember which) had been defined so this would be true at a certain temperature and pressure. Is this the case, or is it just a coincidence? Superm401 | Talk 07:45, 22 September 2005 (UTC)

• This is only true for standard conditions. If water freezes it gets a higher density. If it boils it's density goes down. The fact it's 1gram per cubic cm is pure coincidence. It's the weight and volume that were defined. - 131.211.210.12 07:50, 22 September 2005 (UTC)
  • I mentioned that I understood it was only true in a one case. However, it can't be both defined and a coincidence. Which is it? Superm401 | Talk 08:13, 22 September 2005 (UTC)

A nit to pick. When water freezes it density is lower, this is why ice floats. Most materials are not like this.

The kg was originally defined as the mass of 1 l of water. So the density of water is 1 kg / dm^3, which is 1 g / cm^3. By the way, gram is abbreviated to 'g', not 'gm'. DirkvdM 08:33, 22 September 2005 (UTC)

Thank you. So kilogram was originally defined that way, but no longer is? Also, thanks for the reminder about the gram abbreviation. I'm surprised I messed that one up. Superm401 | Talk 08:36, 22 September 2005 (UTC)

The kilogram (see our article) was originally defined as the mass of 1 L of pure water at 4 degrees Celsius (water reaches its maximum density at this temperature) and under 1 atmosphere of pressure.

Because it was difficult to work with a standard made of liquid water–the stuff sloshes about, evaporates, and leaks, and it's difficult to construct a standard 1 L container–the kilogram was officially defined in 1889 to be exactly equal to the mass of a particular platinum-iridium cylinder currently stored in Paris.

The kilogram is the only SI (metric) unit still defined in terms of an actual physical object. Other units (like the meter or the second) are defined in terms of specific measurable physical constants. (The meter, for instance, is defined as a fraction of the distance light travels in a second in a vacuum. The second is based on the frequency of a particular type of radiation.) This has generated problems—over the last hundred years, the standard kilogram has apparently gained a small amount of mass: about 50 micrograms. For highly precise measurements, such a change–about fifty parts per billion–is significant, and decidedly inconvenient. Scientists are now attempting to develop a new standard for the kilogram that doesn't depend on a physical artifact.

Our article says it lost that amount(50 micrograms). Which is right(cite sources if possible)? Superm401 | Talk 14:26, 22 September 2005 (UTC)

Also, note for future readers: Light travels far more than a meter in a second. According to the definition of the meter, it travels 299,792,458. Still, I understood the point of the anon. Superm401 | Talk 14:28, 22 September 2005 (UTC)

And just in case anyone cares, the meter started out as one ten-millionth of the distance from the North Pole to the Equator, along a meridian passing through Paris. So if someone asks you the circumference of the Earth, say "40,000 km". Okay, that's not exactly right, and it varies according to the great circle chosen, but it's darned close, as well as easy to remember. Similarly, as originally intended, the density of water is 1 gm/cm³. Again, not exactly right, and varying by temperature and pressure, but very close, and easily remembered. One of these that seems to be pretty much accidental, but has the same features of accuracy and memorability, is that the speed of light in a vacuum is 300,000 km/sec. — Nowhither 21:00, 22 September 2005 (UTC)

Still easier to remember is that it's 1 billion km/h. That's about 8% off (it's actually 1,079,252,848.8 km/h) but a whole lot easier to remember (and it's in a more usual unit, km/h, which makes that part of it easier to remember - "well, it's 300,000 ehm ... something"). And for those who need such an easy way to remember it it doesn't matter much how accurate it is. As long as they're not off by a factor 100 or such :) . To stretch the point, it's better to know that the speed of light is about 1000 km/h than not to have a clue (even though it's over 20% off - it's 1225 km/h). And while I'm at it, for converting Celsius to Fahrenheit, in everyday situations don't bother with the x 9/5 + 32. Make that x 2 + 30. Much faster and fairly accurate for everyday temperatures. (it's precise for 10 C and 2 F off for 20 C (70 in stead of 68)). You could also remember that for every 5 C over 10 C you have to substract 2 F, but then it gets complicated again :) . DirkvdM 12:25, 23 September 2005 (UTC)

1 billion km/h. That's nice; thanks. — Nowhither 11:06, 24 September 2005 (UTC)

About hurricans

How does each and every hurrican get its own name, say Katrina, Rita? Is it given randomly by some metrologist? S 07:56, 22 September 2005 (UTC)

• Our Tropical cyclone article explains the history of cyclone names. Currently, the World Meteorological Organisation maintains the naming system originally founded by Clement Wragge an Australian meteorologist. Our NOAA National Hurricane Center states that there is a six-year rotating list with the 2005 list due to be reused in 2011. Capitalistroadster 08:16, 22 September 2005 (UTC)
• See Hurricane#Naming_of_tropical_cyclones specifically. Superm401 | Talk 08:19, 22 September 2005 (UTC)

are forces such as centrifugal and g forces, forms of energy

like the subject matter/heading says

Are forces such as centrifugal or G forces also forms of energy

Energy and force are fundamentally different. Thank you. 204.38.191.99 11:34, 22 September 2005 (UTC)

• See force and energy. - 131.211.210.16 11:54, 22 September 2005 (UTC)

Forces produce work (energy); work done over a period of time is power. Force may be measured in newtons (N), energy is commonly measured in joules (J), and power is measured in watts (W) or horsepower (hp).

However, centrifugal force is not actually a force per se. It is a fictitious force, the effect of an object having a tendency to move in a straight line (inertia), but not being allowed to do so. The force applied to an object in circular motion is the centripetal force, which pulls the object inward; however, the object has enough velocity to travel at a right angle (tangential) to this force, and travels "around" the inward force instead. If there was no centripetal force, the object would travel outward in a straight line along the tangent, but no force causes this outward motion.

G forces are also not forces. Again, they are caused by inertia — an object at rest will tend to stay at rest. So the answer to your question is yes: inertia is mass, and mass is equivalent to energy. ‣ᓛᖁ♀ᑐ 14:32, 22 September 2005 (UTC)

BBE

Hi everyone! ^^

I would like to ...advise...(something like that ^^') that I am from Quebec so my english is not perfect...

I'll begin by presenting myself if you want to understand why I'm searching for that.

I'm 17 yeras old and i'm in a School ..I dont know how to say that but I'm doing electronics in this school ^^'

A teacher gave me an homework and one of the question is : What is the definition of : BBE

Anyone are able to find what is the signification of this abreviation. Even the teacher is'nt able to find it, I cnat find it on the internet And all the information that I have is that:

-It's about electronics -It's about the sound -Apparently that in the defenition, there's a "Bradley" somewhere, but not sure.

It's all what I have founded... if someone have the definition this question...please write it here! ^^'

Thanks in advance

And sorry again for my...poor english ^^'

• The most electronics-related entry I can see at AcronymFinder is "Broadband Equivalent". Acronym Attic lists "Behringer Beyer"" and "Barcus Berry Electronics". There is also a company called BBE Sound. You may like to try the French Wikipedia. Bovlb 15:33, 22 September 2005 (UTC)

Second

Why is the standard definition of the second based on the cesium atom? ‣ᓛᖁ♀ᑐ 14:37, 22 September 2005 (UTC)

Based on atomic clock, it appears to simply be that cesium was the element used in the first accurate atomic clock and became the de facto standard for such clocks. Atomic clocks themselves are used for their fine resolution and precision. — Lomn | Talk / RfC 15:04, 22 September 2005 (UTC)

define a body of water called a straight

It's actually spelled strait in this context. — Lomn | Talk / RfC 15:00, 22 September 2005 (UTC)

And here's your definition: wikt:strait —Cryptic (talk) 15:06, 22 September 2005 (UTC)

Straits are straight channels straitened as they are straught between land. ‣ᓛᖁ♀ᑐ 15:10, 22 September 2005 (UTC)

What is the meaning of 'synthetic human' or a 'synthetic model' ?

What is the meaning of 'synthetic human' or a 'synthetic model' ? Is it something like robots ? I recently found this word in a website which says about future technologies.

I have also occasionally seen this concept, but it is not defined in my encyclopaedia of Science Fiction Concepts ISBN 0-7867-0887-0

Do you watch Star Trek enough to be familiar with the character called Data, who is like an android. There's all kinds of artificial life forms, some humanoid, in science fiction and I think the synthetic one pre-dates Isaac Asimov popularizing the concept of robots. AlMac|^(talk) 18:49, 22 September 2005 (UTC)

Maths: Vectors

Hi everyone...

I'm currently working on a maths assignment (yr 12) and I am so stuck. This is the last question. I haven't got much clue.

C,OAB is a regular tetrahedron as shown where OA = a, OB = b, and OC = c.

G and K are the cenroids of faces OAB and OAC respectively.

1. Prove, using a vector method, that CG and BK intersect.

2. If H is the point of intersection of CG and BK find OH.

3. What ratio does H divide CG?

4. Prove that the altitudes of a tetrahedron are concurrent.

• Bold = vectors.

If anyone could help me that will be extremely helpful. Thank you so much.

- Cindy

• Well, you could start by noting that:
  • In a regular tetrahedron, the line joining the centroid of a face to the opposite vertex is perpendicular to that face (an altitude), and passes through the centroid of the tetrahedron.
  • A centroid can typically be determined by taking the mean of the defining points.
  • Two lines intersect if their four defining points are coplanar.
  • Four points are coplanar precisely when the parallelopiped they define has volume zero.
  • The voume of a parallelopiped can be calculated as the scalar triple product of its three edge vectors.
• Some or all of those may be useful to you. Good luck with your homework. Bovlb 20:03, 22 September 2005 (UTC)

What should I do with my Internet venture idea?

I am having a new idea for an Internet Venture. But dont have a business plan. Just having the idea, thats all. What should I do so right now?

One first step you might consider is reading some books on starting your own business. You will find lots of them at your local library or in a bookstore. You might also enquire at your local community college whether they have a suitable short course on this topic; a friend of mine is in the process of doing just such a course. There may also be some government programs that assist people setting up small businesses. Good luck! --Robert Merkel 00:21, 23 September 2005 (UTC)

Moles

How many atoms are contained in 1 mole of Si (silicon) and how many molecules in 1 mole SiO2?

• The answer is the same in both cases: Avogadro's number, about $6.022\times 10^{23}$. -- DrBob 15:58, 22 September 2005 (UTC)

The reason for which is that a mole is a measure for the number of molecules (be they atoms or not). So no matter what substance you have, one mole of it has by definition the same amount of molecules. Of course the number of atoms in one mole of SiO2 is three times as high because one such molecule contains 3 atoms. But I'm diverging now. DirkvdM 18:56, 22 September 2005 (UTC)

But I'm diverging now. I hate it when that happens! — Nowhither 21:03, 22 September 2005 (UTC)

fractal

See fractal. --R.Koot 18:57, 22 September 2005 (UTC)

Where have all the dolphins gone?

What does the acquatic wildlife do during a hurricane? Do they swim deeper? Is there catastrophic loss of life?

Thank you.

Most oceanic life just doesn't care; hurricanes and other weather patterns significantly affect the surface only. — Lomn | Talk / RfC 18:35, 22 September 2005 (UTC)

Dolphins, on the other hand, being air breathers, probably have a harder time of it. Interesting question, I don't know the answer. -- Jmabel | Talk 05:33, 23 September 2005 (UTC)

Why would dolphins care either? There's still plenty of air around in the usual place. Unless they get sucked up by a tornado... Mark¹ 07:52, 23 September 2005 (UTC)

Steel

my question is 'What is steel' i no it is a metal but what is it!

Please answer my question a.s.a.p

Thankyou :D Anon (please)

Have you read our article on steel? — Lomn | Talk / RfC 18:33, 22 September 2005 (UTC)

(Also, rather than posting 3 similar questions, you can scroll to the bottom of the page and edit the first one) — Lomn | Talk / RfC 18:37, 22 September 2005 (UTC)

You could also try our article on alloys. Physchim62 14:24, 23 September 2005 (UTC)

how often do eclipses happen?

See eclipse, lunar eclipse and solar eclipse. --R.Koot 18:56, 22 September 2005 (UTC)

how old are the great redwoods of california?

See Redwood_National_and_State_Parks. --R.Koot 18:55, 22 September 2005 (UTC)

geology question

an adjective describing a liquid in which ions, atoms or molecules dissolved in it are so numerous they get close enough to chemically bond is called?

...a homework problem. --jpgordon∇∆∇∆ 21:04, 22 September 2005 (UTC)

No idea, but it strikes me as being in the field of chemistry, not geology. — Nowhither 21:05, 22 September 2005 (UTC)

I'd go with solvent, because ions dissolved in any solution are close enough to bond. That is how precipitation caused by Single displacement reactions occurs, for a start. Superm401 | Talk 21:44, 23 September 2005 (UTC)

Volume of the Proton

Matter is defined as occupying space and having mass. A proton must be matter since tangible matter is composed of protons in addition to other subatomic particles, and moreover the proton has mass (1.6726 × 10−27 kg, according to your article about the proton). So, a proton must occupy space. What, then, is the volume of a proton? Furthermore, what is the volume of the neutron, the electron, and so on?

[5] has a writeup on neutrons:

the volume of a neutron is approximately 5.6 x 10^-54 km³

I would expect protons are similar; however, it increasingly appears that protons and neutrons aren't "solid" objects per se, but rather a collection of quarks which themselves can move about somewhat. [6] Electrons are even less suited to discussions of volume as their positions are discussed in probabilistic terms only (I believe the Heisenberg Uncertainty Principle is the reason for this). — Lomn | Talk / RfC 20:41, 22 September 2005 (UTC)

Sounds fine, although I must say that, when measuring the volume of a subatomic particle, the cubic kilometer is probably not the most appropriate unit. — Nowhither 21:08, 22 September 2005 (UTC)

I suspect these all have densities similar to neutronium, or 10¹⁴ to 10¹⁵g/cm³. This would give:

Particle	Mass (g)	Volume (cm³)
Electron	9.1094 × 10−28	9.1094 × 10-42-3
Proton	1.6726 × 10−24	1.6726 × 10-38-9
Neutron	1.6749 × 10-24	1.6749 × 10-38-9

...which at least agrees with NASA's neutron volume (though one wonders why anyone would describe particles in cubic kilometers). However, except for the neutron, it's probably impossible to find the true densities, due to the extreme difficulty of accumulating enough charged particles in one location to measure.

The electron seems like it may be somewhat denser, since it is only one particle while the proton and neutron are composed of three quarks. Also, it is sometimes claimed to be a charged black hole (see black hole electron), which, if correct, would presumably give it a Schwarzschild radius of 1.3526 × 10^-57m, a volume of 1.0366 × 10^-170m³, and a density of 8.7879 × 10¹³⁶g/cm³, assuming objects smaller than the Planck length can exist. ‣ᓛᖁ♀ᑐ 20:58, 22 September 2005 (UTC)

It would be interesting to compare the density of quark stars. Does anyone know what the Tolman-Oppenheimer-Volkoff limit is? ‣ᓛᖁ♀ᑐ 21:40, 22 September 2005 (UTC)

printing

How would i make the handwrite on a new written postcard look old?

Use sepia ink and a copperplate hand. Then let the thing sit in the sun for a few weeks. --jpgordon∇∆∇∆ 21:34, 22 September 2005 (UTC)

You could also try soaking it in tea for that brown, aged look. --Sum0 20:37, 23 September 2005 (UTC)

Baking it carefully at a reasonably low temperature works very well. Superm401 | Talk 20:44, 23 September 2005 (UTC)

Earliest Fossil Egg

Where was the earliest fossil egg found?

-anon

As yet, we do not have an article on Fossil eggs nor does our fossil article provide much detail. However, these articles by The San Francisco Chronicle on dinosaur fossil eggs [7] and the National Geographic on bird fossil eggs [8] should be of some assistance to you. I have added Fossil eggs to Wikipedia:Requested Articles so that someone can write an article on this topic. Capitalistroadster 00:08, 23 September 2005 (UTC)

which part of the tree contains live wood?

• Depends on the tree, but potentially all of it. -- Jmabel | Talk 05:34, 23 September 2005 (UTC)
  • Well, it does depend on the tree, but most "normal" trees (not, for example, palm trees) have living cells in the outer sections of their trunks (except the bark) and dead cells in the interior and the bark.

    Details: There is a thin, roughly cylindrical shell called the vascular cambium, which is where a tree does its growing. The outside of the cambium produces new phloem cells, which do "food" transport. The inside of the cambium produces new xylem cells, which do water & nutrient transport from the roots. Old phloem gets shed with the bark, but old xylem just sticks around, forming a core made of dead cells that provides structural support to the tree. Most trees add a new layer of xylem each year. The old dead xylem layers are the rings one can see on a stump.

    It appears to little-old-nonexpert-me that this ability to make a single, strong core out of dead xylem is probably one of the main factors that allows trees to grow so tall. Lots of plants have this phloem/cambium/xylem structure, but in many of the smaller ones, the cambium does not form a single large cylinder, but rather many small ones (vascular bundles). Thus, the xylem is scattered and strength is lost. I imagine this is one reason you will never see (say) a celery tree. On the other hand, the multiple bundles probably allow for faster growth ("growing like a weed"). Interestingly, palm trees have the multiple vascular bundles, but can still form large, strong trunks.

    Much of this is hinted at in our tree and xylem articles, but never quite stated. Maybe it should be.

    — Nowhither 00:14, 24 September 2005 (UTC)

Any Airsofters in the LA county area?

Any Airsofters in the LA county area?

Oh Jesus Christ. Is the concept of the Reference Desk that dense and foreign to some people? Garrett Albright 12:21, 23 September 2005 (UTC)

That's a valid question, just not the kind you want to answer. Superm401 | Talk 13:44, 23 September 2005 (UTC)

• It's an easy question to answer, and perfectly valid. Given the huge population of LA, and the burgeoning popularity of Airsoft, the answer is indubitably, "Yes". --jpgordon∇∆∇∆ 14:38, 23 September 2005 (UTC)

• Okay, please do not bite the newcomers. To the original poster: The answer is "yes", there are airsoft players in that area. Perhaps you are one of them. However, that is obvious. I would guess that your real reason for posting here is to meet airsoft players (?). If so, then you are in the wrong place. The Wikipedia Reference desk is for answering factual questions, not for meeting people. A quick Google search turns up many airsoft-oriented websites. I suggest you try one of them. — Nowhither 00:20, 24 September 2005 (UTC)

Electron - Proton

What we have been taught is that electron revolves around a proton because of electromagnetic force of attraction. But this force is same for both the electron and proton. This is when we neglect other forces like Gravitation since it is only 1/100 th times of electromagnetic force acting. Then why do electrons revolve around the protons instead protons can move around an electron??

Yes, the force on the two is the same (in accord with Newton's third). However, the proton is 2000 times more massive that the electron, so it remains relatively stationary. Just like the Earth orbiting the Sun, both objects actually orbit the center of mass, but the center of mass is closer to the more massive body. In both cases, the more massive body is so much more massive, that you can often neglect the massive body's revolution. -Lethe | Talk 02:24, 23 September 2005 (UTC)

Isn't it a bit 'oldfashioned' to think of an electron evolving around the nucleus? This is 'particle-thinking', but elementary particles can also be seen as waves. I envision electrons and other 'particles' as sort of pulsating three-dimensional waves. Lomn mentions in 'Volume of the proton' above, that the position of electrons can only be expressed in probablistic terms. If the electron can als be seen as revolving around the nucleus then I can only rhyme all this together by seeing the electron as occupying the same space (on average) as the nucleus, just covering a wider area. So the amplitude of the wave would have to be (much) bigger. If I'm talking gibberish feel free point that out to me :) . DirkvdM 14:00, 23 September 2005 (UTC)

When one starts discussing particles as small as this, the distinction between particle and wave mechanics gets blurred, since both properties can be present when quantum effects present themselves. Discussing it in probablistic terms is one way of expressing it, but there is a mode of thought that a paricle really occupies a 'quantum area' of space and exists everywhere in that space simultaneously, whereas probablistic theory suggests it has a chance of being at an point based upon a formula.

It is a bit "old-fashioned", yes, but it is not too far from the truth. "Electrons evolve around a positively-charged nucleus, to which the are attracted by Coulombic (electrostatic) forces" is a correct statement: they just don't obey Kepler's laws... Physchim62 14:32, 23 September 2005 (UTC)

It is old-fashioned (which doesn't stop almost every physics student from doing the calculation at some point), but the principle still applies. When treating the proton and electron as a two-body problem, you can reduce it to a one-body problem with a reduced mass orbiting about the center of mass. Since the electron is so much smaller than the proton, the reduced mass is basically the electron mass, and the center of mass is basically the proton position, so you're basically solving a problem with a stationary proton.

When you actually treat the situation quantum mechanically, it turns out that you can make the same transforms (it's the same potential afterall), and you end up solving a quantum mechanical problem of a reduced mass in a symmetric potential about the center of mass. So although the result is different, you can make some of the same conclusions: that the proton is relatively unaffected and that the solutions for the wavefunction of the reduced mass will basically be the wavefunction (orbitals) of the electron. There's more information at hydrogen atom and hydrogen-like atom. — Laura Scudder | Talk 14:32, 23 September 2005 (UTC)

Wintergreen LifeSavers

Why do wintergreen lifesavers "spark" when chewed? ---12.37.12.134 --12.37.12.134 02:29, 23 September 2005 (UTC)

It appears to be a form of triboluminescence. This seems a useful explanation.-gadfium 03:40, 23 September 2005 (UTC)

The American roulette?

If two persons both eat the same amount of beef each and every day from the same large pool of cattles, which person is more likely to get mad cow disease in the long run?

1. Mr. A: Eat hamburgers made from grinding and mixing many many many cattles' meat.
2. Mr. B: Buy a frozen cattle carcass each time and eat the dead body from head to tail.

I guess Mr. A's risk is much higher than Mr. B's. But could it be possible that by mixing a few thousand dead cattle's meat at a time, the concentration of bad prion would become too low to be threatening? -- Toytoy 03:38, 23 September 2005 (UTC)

In the UK, it's thought those who got vCJD generally got it through hamburgers and the like. Bad slaughtering practices are much more problematic when you don't do it yourself and then mince the remains to cover any mistakes... Shimgray 11:56, 23 September 2005 (UTC)

I would agree that it's Mr. A because the smallest piece of meat you can realistically grind is still probably large enough to contain millions of prions. Superm401 | Talk 13:41, 23 September 2005 (UTC)

OK, I know you can't use meat puree to make a good hamburger. A piece of hamburger, in theory, may only have hundreds of cattles' meat in it. Then how about sausages such as hot dogs? These products are manufactured in very big factorie (lots of cattles), the meat is pulverized and then thoroughly mixed. Does it make franks more dangerous than hamburgers? -- Toytoy 14:05, 23 September 2005 (UTC)

More cows means more dilution, so the amount of germs you ingest may be below some threshold. I've heard that in order to get malaria you have to get bitten by an infected mosquito several times (don't know how many and over what period of time). Mad cow disease might be completely different though. Just a consideration. DirkvdM 14:20, 23 September 2005 (UTC)

Look again at what I said above. A grinder(not blender) probably outputs shreds of meat that are maybe about, say, half a gram. I don't know how many prions could fit in that, but I'm pretty sure it's 100s of 1000s. I think that's enough to infect you. Then again, I could be wrong. But there's my argument. Superm401 | Talk 20:48, 23 September 2005 (UTC)

Difficult to say, because we don't know the level of infectiousness of the prion involved, but my feeling would be that route A is more hazardous (for the reasons discussed above). Physchim62 14:37, 23 September 2005 (UTC)

1. 1 is eating many many cattle over a long period of time. #2 is eating one cattle over a long period of time. Assuming every cow you eat has an equal chance of having bad prions in it (big, artificial assumption), it would seem that #1 would be more statistically more hazardous. --Fastfission 22:51, 23 September 2005 (UTC)

I guess it is still unknow how much prion would cause one to be infected. If we hire many vegetarians and feed them infected meat and wait a decade, we may learn what are the minimum prion concentrations to infect 10%, 20%, ... 50%, ... 90% and 100% of people after consumption of a portion of beef. But we simply cannot try this on people ... at least to vegitarians.

Had anyone tried this on animals? -- Toytoy 00:40, 24 September 2005 (UTC)

To bring a bit of perspective to the whole "mad cow" panic, it's worth remembering that in the 20-or-so years since BSE became apparent, fewer than 160 humans have died in the entire world from nvCJD. Eating lots of hamburgers is vastly more likely to kill you from heart disease than CJD. -- Arwel 13:24, 24 September 2005 (UTC)

Very possibly, many cases were not diagnosed, some of them are still hidden, but the actual numbers may still be a very low number in comparison of other kinds of deadly food poisoning or long term health hazards (tran fat, salt, cholesterol ... problems).

I guess it is because this disease has a very low rate of transmission among animals and humans. A cow eating dead cows has a very low chance to get the disease. A man eating infected cows also does not ge it most of the times. However the rate is not that low to make this disease a non-issue.

I also wonder if dilution plays a part in lowering the rate of infection. Are hamburgers more dangerous than steaks? Are hot dogs even more dangerous? Shall we restrict or increase the size of the batc during meat processing if mad cow is the only concern?

If a tiny itsy bitsy piece of meat is infectious, then an infected cow broken apart into a million pieces may infect hundres if not thousands people. If that itsy bitsy piece of meat is not infectious, then possibly no one gets mad cow because of it. -- Toytoy 14:54, 24 September 2005 (UTC)

Oil

For some reason, my face is always oily, why does this happen and is there a way of preventing it from happening?

Thanks, Tasha

The simple answer is that skin oils help protect your body against attack by microorganisms. Excess production can be due to many factors that vary greatly from person to person, including, but not limited to, diet, exercise, climate, medical conditions, and ethnicity. I think it would be a good idea to talk about this with your family doctor, who is more knowledgeable about your circumstances than we are.--inks 06:56, 23 September 2005 (UTC)

What is evolution?

See evolution. - Fredrik | talk 04:59, 23 September 2005 (UTC)

Bermuda Triangle

What is Bermuda Triangle?

• See Bermuda Triangle. -- Jmabel | Talk 05:36, 23 September 2005 (UTC)

branded product marketing

(no question asked)

Did you have a question? — Nowhither 00:24, 24 September 2005 (UTC)

Quarks

Are there important differences between atomic nuclei and quark matter such as quark-gluon plasma? How can it be experimentally determined that a nucleus is composed of distinct nucleons? ‣ᓛᖁ♀ᑐ 05:33, 23 September 2005 (UTC)

• For the second question, the idea has been round since Prout's hypothesis in the early nineteenth century. The integral nature of atomic number was demonstrated by Henry Moseley, who discovered what is now known as Moseley's law. The last major paradox was resolved by the work of Francis William Aston, who demonstrated the existence and integral mass of isotopes. Physchim62 19:46, 24 September 2005 (UTC)

australian native animals

where is the emu found in australia?

Throughout most of it. See [9]--inks 06:46, 23 September 2005 (UTC)

Or you could try our article on emus, which has a picture representing their range. --Robert Merkel

Although generally not in metropolitan areas, I've never seen an emu near the city, so generally rural areas on the map at emu. --Commander Keane 10:50, 23 September 2005 (UTC)

Why does wind gust?

I know that wind is caused by air movements from areas of different pressure - and the closer these areas of different pressure are to each other the stronger the wind it. I also think I know that its the rotation of the earth that stops it all evening out into one average pressure area. I don't understand though why the windspeeds are not constant but they gust - sometimes much more than others? Thryduulf 08:10, 23 September 2005 (UTC)

Because pressures are not a constant, even in a given location at a particular time of year. Chaotic variations in temperature and water vapor concentrations mean pressures are always changing as well. This in turn results in varying windspeeds. Superm401 | Talk 13:35, 23 September 2005 (UTC)

Does it cause cancer?

My friend asked me an uncertain question concerning blood clotting (coagulation), so I got Wiki to help him solve his question, here it is: Does it cause cancer (anything cancer, like blood cancer etc) if sb had serious blood clotting?

• Excessive blood clotting is certainly a problem, but as far as I know it doesn't cause cancer. Cancers are malignant cells with excessive growth and even they need an uninterrupted blood flow to deliver nutrients to their cells. So I would say serious coagulation is just as bad for cancers as it is for normal tissue. See Cancer and Leukemia and for more info. - 131.211.210.12 11:13, 23 September 2005 (UTC)
  • Even if excessive blood clotting -did- lead to cancer, you would not live long enough for it to grow to any significant size. You would almost certainly die of a heart attack or stroke not long after blood clots started forming in your circulatory system.--inks 12:05, 23 September 2005 (UTC)

Usually the causal relationship runs the other way—a cancer that affects the blood-forming tissue of the body (the bone marrow) leads to over- or under-proliferation of megakaryocytes–cells that turn into platelets and cause clotting–leading to clotting disorders.

Large tumours secrete chemical signals that drive angiogenesis:the formation of new blood vessels. (Without a blood supply, cells at the center of a large tumour don't receive sufficient nutrients and oxygen, and the tumour stops growing.) These new blood vessels tend to be irregularly formed and tortuous in shape; the blood flow in them is turbulent and disordered. This turbulent flow tends to encourage clot formation; those clots can be dislodged and cause trouble elsewhere in the body.

Also, there is a correlation between deep vein thrombosis or pulmonary embolism (blood clots in the deep veins of the leg and clots in the lung, respectively) and diagnosis (recent past or future) with cancer. The mechanism for this is not well understood (as far as I know) but probably has to do with clotting stimulated by inflammation of tissue around the tumour site.

So to answer your question—no, clots probably don't cause cancer. Cancer, however, can cause clots. TenOfAllTrades(talk) 13:27, 23 September 2005 (UTC)

Example tutorial of TI-92PLUS

Do anybody know about the usage of TI-92PLus?I recently given a assignment which want me to write a programme by using this calculator.If possible,please give me some examples or tutorial of the programme?Is there any websites related to the programming of this calculator too?Thanks.

I suggest you start by reading the manual, if it's anything like the one for the TI-83 Plus, you'll find plenty of examples in there. --Pidgeot (t) (c) (e) 13:42, 23 September 2005 (UTC)

Help using Internet explorer

I am using Internet explorer. All these days, I used to download pages, disconnect, and view pages later. But suddenly, for the last ten days, when I close the browser windows and open it later, I cant view pages offline. It says 'page not available offline'. What should I do? I tried by going to Internet options, but after that dont know what to do. Please help.

Your cache may be filled. Try clearing it through Internet Options, as well as verifying that its settings are correct.

Alternatively, you can use Save As to save a (temporary) copy of the page to yuor harddrive so you can view it from there after you disconnect. --Pidgeot (t) (c) (e) 17:20, 23 September 2005 (UTC)

If you install another browser (and while you're at it, why not make it a better one like Mozilla, Firefox or Opera ... ) and try it with that, then at least you'll know if the fault lies with the browser or that you should look elsewhere. This is also a much more general tip. Keep an alternative handy, such as a second ('free') internet connection. DirkvdM 06:28, 24 September 2005 (UTC)

You might also wanna check you are visiting the same pages. Some script-generated pages cannot be cached by the browser.--Fangz 12:58, 26 September 2005 (UTC)

what exactly is a buckeye

Have you checked buckeye? In the context of Ohio State, it refers to the first entry in the disambiguation. — Lomn | Talk / RfC 17:54, 23 September 2005 (UTC)

Thunder/lightening

I have read both the articles related to this subject but I'm still not sure about one thing. Can thunder occur without the presence of lightning, and visa versa. Thanks, DEE

Lightning causes thunder, so as a general rule, no and no. However, many things other than lightning can cause sounds similar to thunder (explosions, sonic booms, and so forth) and it's not always possible to observe both lightning and thunder at once. — Lomn | Talk / RfC 18:24, 23 September 2005 (UTC)

Ehm, when you observe thunder and lightning at once you might not be able to tell the tale :) . But more seriously, there are different sorts of lightning, such as Ball Lightning, which makes a crackling sound if any at all. Strangely, the lightning article doesn't mention St. Elmo's Fire (which I'll amend next), which, I imagine, won't make any sound either. By the way, my grandmother once saw a lightning ball come in through a window, hover for a bit, and go out again. Only after her death did people learn that such things really exist. The poor woman was branded a liar. No-one ever believed her. DirkvdM 06:53, 24 September 2005 (UTC)

Austim and Music Therapy

I am looking for any information on the treatment of autistic children through music therapy. Anything about it's effectiveness, methods, etc, would be incredibly helpful. I would also like to find any information disagreeing with this method. Thank you so much.

anon

• I don't know the answer to your question, but hopefully you can find something by reading our article on autism and the list of autism-related topics. I believe there are several Wikipedians with a special personal interest in autism, so that area has received some attention. Bovlb 19:39, 23 September 2005 (UTC)

Genetic Engineered Food

Seems to me the risks far outweigh the benefits, yet USA Agribusiness is gung ho headed that way. Am I missing something, or is there a failure of government oversight of a business area that does not give good enough lip service to quality of safety?

Risks:

• Many nations want grain, and animal products from grairi, where there was no genetic engineering. The USA is no longer able to serve those markets, because of massive contamination, and inability to police the contamination. For example, a farmer who tries to make the pure product, cannot, because contamination is freely in the winds that other farms "breathe." Thus, as genetically engineered byproducts filter down the food chain, the USA locks itself out of more global markets.
• Today in much of South and Central America, and southern states of USA, there is a real serious problem with Killer Bees. This is a man made problem, that came about thanks to experiments in breeding a better honey producer, but the experiment had very negative consequences.
• Once upon a time, there was Mad Sheep disease (Scrapie) caused by short cuts in managing food supply in agriculture, which spread to cattle, so then there was Mad Cow disease, then there were experiments to try to understand this using Deer in captivity, deliberately given the disease so that we had Mad Deer, but due to the experimenters not understanding how the disease could spread, the Mad Deer in captivity licked fences, which were also licked by Wild Deer at edges of the enclosures, so now Mad Deer was in the wild, and eventually spread to all of North America, which gave the disease back to animals in agriculture, such as pigs, and to the animals that eat Deer, such as mountain lions. So we are on a collision course with a worse disaster, fueled by efforts to do cost savings in agriculture, with government oversight that is driven by rear view mirror to past disasters, rather than oversight of theories about future risks.

Benefits:

• When there is a wide range of quality of animals producing eggs milk meat, whatever, this is a breeding technique to make copies of those that are the best.
• Genetic engineering, cloning, and Transgenetics is a real cool thing to do. Any company that announces successes will get oodles of money from venture capitalists who think there's lots more profits down the road from this.
• Ok, we know there are major disasters down the road, but we can still make oodles of profits capitalizing on the industry that is exploring this high risk area, then hopefully get out of the business, before the disasters put them out of business.

AlMac|^(talk) 22:40, 23 September 2005 (UTC)

AlMac: The question of whether using genetically modified organisms to produce food is a Good Thing is one I will leave to you and others to decide. However, you missed some of the most important entries in the "benefits" list. Most of these, in the end, deal with cost. Using GMOs we can produce food more cheaply. We do this by creating GMOs that, compared to their natural counterparts:

• Produce more food.
• Have greater disease resistance.
• Mature faster.
• Can grow in more adverse climates.

By making food more cheaply, food producers get to spend less money. Someone might say, "Yes, because they are greedy." Well, I'm greedy too. I want a lower food bill. Don't you?

It should be noted that cost reductions also have applications in combating hunger in developing nations. As does creating a GMO that produces more nutritious food than its natural counterpart.

Lastly, I'd note that at least one of your "Risks" arguments isn't quite right. "Killer bees" were not created through modern genetic engineering, but through old-fashioned interbreeding. This phenomenon has been going on for thousands of years and, in general, has been quite safe and successful. A single isolated example is not a good argument against it. And it is certainly not an argument against modern genetic engineering, since it was not used in this case.

Again, I am not arguing a position here. I just saw that your list of "risks" and "benefits" seemed awfully lop-sided. You asked whether there has been a failure of government oversight. I'd say that is quite possible.

— Nowhither 00:44, 24 September 2005 (UTC)

And mad sheep, cow and deer diseases have nothing to do with genetic engineering (or am I now missing something?). Which leaves only the first risk from AlMac's list. Which is scary enough by itself. But I've heard of another one. Genetic engineering can also be used to make crops more resistant to pesticides, which means farmers may (and will) start using them more liberally, which has to have negative side-effects.

But more in general, genetic engineering is rather like a boosted form of old-fashioned interbreeding, which in turn is a boosted form of natural selection. In both cases things are left less to chance, which means developments go faster. And with interbreeding we've created a situation in which diseases can spread much faster. Whole fields of plants that are all the same means that if a disease is introduced it will spread very fast. Add to that that the plants are selected on specific traits and not others, thus possibly leaving out natural defence mechanisms we don't understand yet (and there's a whole lot we don't understand when it comes to the mechanisms in nature). The lack of biodiversity also means that if a disease spreads it will wipe out all plants. That's the result of the first boost. This second boost has a potential to go farther still, which is scary.

To come back to the original question. If all this is left entirely to private companies the risk is way too high that they won't care about the long-term effects. I'm ultimately in favour of using genetic engineering (if only for scientific research), but it has to be done with extreme care, not rushing things. And private companies are by their very nature not made of the right stuff to do this. This has to be done by governments. So yes, there's a failure of government oversight. Moreover, the governments of not just the US but in the whole world should not just restrict themselves to oversight, but completely take over the industry. We're meddling with something we don't sufficiently understand. DirkvdM 07:27, 24 September 2005 (UTC)

I see something missing from your list of benefits. It's not just more food, but we can get better food. A great example is golden rice, which is as easy to grow as normal varieties, but has more vitamin A. It was designed specifically to help areas with vitamin A shortages (like most of Africa Image:Vitamin A deficiency.PNG). I think someone who wasn't used to a full belly might disagree on whether the risks really outweighed the benefits. — Laura Scudder | Talk 08:05, 24 September 2005 (UTC)

why is the sky blue

See Diffuse sky radiation. — Nowhither 00:47, 24 September 2005 (UTC)

The short answer is one quoted from a radio commercial I've been hearing lately: "All colors have wavelenghts that are diffused by oxygen and nitrogen. Since blue has the shortest wavelength, it's diffused up to ten times more, so the human eye sees more of it than any other color." I hope I haven't broken any rules by quoting that! Btw, what the heck did that article say? I couldn't make heads or tails of it. Hermione1980 01:01, 24 September 2005 (UTC)

No you didn't break any rules. See Fair use. What that means is this: oxygen and nitrogen are the two most common substances in air. "Diffused" in this case means "scattered". Light is a form of (very rapid) vibration, waves in other words; the wavelength of light is the distance it travels in a single vibration/wave. Different wavelengths of light are seen as different colors. Red is longest (in the visible range), then orange, yellow, green, with blue/violet being the shortest. Shorter wavelengths are scattered more. That means that red and yellow light tend to pass straight through the air, while blue light tends to bounce around a little. Almost all the light in the daytime sky comes from the sun. But blue, since it bounces around, may look like it is not coming straight from the sun, but rather from many directions. Thus, the sky, away from the sun, appears blue. — Nowhither 01:17, 24 September 2005 (UTC)

See also Rayleigh scattering. TenOfAllTrades(talk) 01:26, 24 September 2005 (UTC)

-1=1

A "proof" for the idea that -1=1 was posted on your page about the imaginary number i. I have replicated it in this question for quicker reference:

-1=i*i=sqrt(-1)*sqrt(-1)=sqrt(-1*-1)=sqrt(1)=1

However, your page says that this is incorrect because square roots only work for real, positive numbers. Your page on the number -1 says that -1^2/2=-1 and sqrt(-1^2)=1 therefore 1 cannot equal -1. However, a friend of mine says that this is incorrect because sqrt(-1^2)=sqrt(-1) though -1^2=1; I have written to you in order to resolve this dispute.

Thank you for your time and patience.

I'm not sure exactly what you're intending to say here because of the way you've written the math symbols. Can you go back and put gratuitous parentheses to make clear exactly what you mean(particularly at "-1^2/2=-1"). However, I can tell you you're friends wrong in saying sqrt((-1)^2)[by the way "-1^2" means "-(1^2)" so you should have said "(-1)^2" but I knew what you meant]. sqrt((-1)^2)=sqrt(1)=1, because the inside is simplified first by order of operations. Superm401 | Talk 01:16, 24 September 2005 (UTC)

This problem can be explained in several ways. My favorite explanation is that there is no "nice" function called "sqrt" on the complex numbers. Numbers have two square roots. But a function has to have a single value. When we deal with square roots of positive real numbers, we fix this by letting "sqrt" of a positive real number be the positive square root, not the negative one. But there is no nice way to fix this problem for complex numbers in general. This is probably what was meant by the statement that "square roots only work for real, positive numbers". In particular, the problem with the "proof" above is in the third equality:

sqrt(-1)*sqrt(-1)=sqrt(-1*-1).

There is simply no way to define "sqrt" as any sort of square root function that makes this true.

As for your dispute, your friend is wrong. The statement

sqrt((-1)²) = sqrt(-1)

is false for all ways of defining "sqrt" as a square root function, since this says that sqrt(1) = sqrt(-1), while those two numbers (1 and -1) have no common square root.

The lesson to be learned from all this is that we don't get to apply supposed mathematical "rules" anywhere we want, but only where they do, in fact, apply. And rules that apply in certain special cases may not apply in general. In particular,

sqrt(a) × sqrt(b) = sqrt(a × b)

works fine when a and b are nonnegative real numbers. That's what we were all taught in school, and it is correct. However, this does not mean that this applies more generally to all pairs of complex numbers. In fact, it does not.

— Nowhither 01:10, 24 September 2005 (UTC)

None of the explainations here make sense to me. The part about the square root of a real number being defined as the positive root is true. The part about no nice way to fix this for complex numbers is not true. Square roots of negative numbers are defined as mapping to the set of imaginary numbers, thus 'i' is an imaginary number equal to square root of -1. Also, i*i is defined as equal to -1 because of this.

i is indeed a square root of -1, but so is -i, and (-i)*(-i) is also -1. You can't say that i is "equal to the square root of -1", because "the square root of -1" describes two numbers that are unequal. So how do you tell them apart? You can't say "take the positive one as the square root" like you do for real numbers, because neither i nor -i is positive. (Don't let the notation deceive you; remember that i and -i are perpendicular to being positive or negative.) RSpeer 05:17, 25 September 2005 (UTC)

• Look at it this way. In school we were taught that the rule "sqrt(a) × sqrt(b) = sqrt(a × b)" is correct for all positive real numbers. Maybe you missed the "positive real numbers" part, but, I can assure you, it was (or should have been) mentioned. Now, does this rule apply to complex numbers in general? No, as the original problem in this thread shows. It may seem intuitively true to you that this rule applies to anything with a square root. However, in mathematics, we do not base our notions of truth on intuition; we prove them to be true. Many properties of the complex numbers seem non-intuitive to people familiar only with the real numbers. This is perhaps one of them.

  And, regardless of whether it seems right, it is true that there is no nice way to define a square root function on all complex numbers. If you want to be formal, then substitute "continuous" for "nice".

  — Nowhither 17:47, 26 September 2005 (UTC)

5ht receptors

(no question asked)

Did you have a question? — Nowhither 01:11, 24 September 2005 (UTC)

Please review our article on Serotonin, and ask again if you need more detail.-gadfium 03:04, 24 September 2005 (UTC)

Codec hell

Well, I just got my computer and was trying to open a few video files, so I downloaded some codec packs. The first was ACE mega codec pack. It was great, opened tons of stuff, except this one divx video with some interleaving problem... Well, I removed ACE, and got a few other codec packs from free-codecs.com (k-like, xp and all in 1).

Installed all in 1 first. Didn't work. Uinstalled it. Installed XP. Didn't work. Uninstalled. Insalled k-like. It worked. But now WMP won't open the most basic video files (wmvs), and the automatic download of codecs feature returns an error (no appropriate codec could be found).

So, this sucks. Not even half of my videos are opening right now and I was wondering what I should do. Is there any tool that lets me remove ALL codecs from my computer, so I can get them all again? Is there any immediate problem on not having any codecs installed? Help! Kieff | Talk 01:30, 24 September 2005 (UTC)

Can't help with codec removal, but if you just want to play the videos, VLC player opens just about anything, and you don't have to mess with codecs.[10]--inks 20:24, 24 September 2005 (UTC)

You may be able to uninstall and reinstall Windows Media Player, or upgrade to a newer version, which will fix the codec problems. Rob Church ^{Talk | Desk} 21:14, 25 September 2005 (UTC)

Whilst I'm happy to recommend VLC player myself having used it these past couple of days, it doesn't seem to open the .wmv files I have.

Well, I managed to uninstall WMP and reinstall it. Things seem to be working now, thanks everyone. I'll avoid codec packs after this incident. Kieff | Talk 19:33, 26 September 2005 (UTC)

APPLICATIONS OF GRAPH THEORY TO COMPUTER SCIENCE

Sir,

Can you get me any three applications of graph theory to computer science" and what way it is used and details about that. Thank you. --anon. Question reformatted by Robert Merkel 08:53, 24 September 2005 (UTC)

Well, actually, I can, but I've done enough homework for one lifetime. Have you considered reading our article on graph theory, or perhaps your textbook? By the way, DON'T USE ALL CAPITALS BECAUSE IT'S INTERPRETED AS YELLING!--Robert Merkel 08:53, 24 September 2005 (UTC)

How temperature affect the atmosphere pressure?

Can you tell me how temperature affect the atmosphere pressure at an area?Is there any equation uses to calculate the atmosphere pressure of a place which related to the change in temperature?

• Yes there is. Try Combined gas law (and the related laws mentioned in the article. Atmospheric pressure may also be of interest to you. - Mgm|^(talk) 11:59, 24 September 2005 (UTC)

Alternative to the Big Bang theory

I've long had an alternative to the Big Bang theory, which surfaced when I gave an answer to Wikipedia:Reference_desk/Science#A_Variable_Speed_of_Light hereabove. I'm very much a layman when it comes to this field, but I made a prediction that went against the accepted theories but turned out to be correct, which is a bit of a theoretician's wet dream :) . So I now venture to put this theory before you. Here goes.

As a kid I heard the expanding universe explained as a balloon with dots on it. On that everything moves away from everything else, which is exactly what we observe in the universe. But then I wondered, how do you know a balloon expands? My thought was that you know that because the only alternative is that the room you're in (and everything else) is getting smaller. Which would be silly. The simplest solution is held to be true, which is that the balloon expands. But for the universe there are (by definition) no surroundings to compare with. There is no reference frame, so one has to assume the size of of the universe is given. I couldn't think of a solution then.

But later I realised that you can also compare the sizes of the universe and everything in it. If the size of the universe is given then the stars and such must be getting smaller. Hmmm, stuck again.

Later still I imagined falling into a black hole. I was supposed to get stretched out. But that's seen from the framework of an outside observer. For me, I'm part of the spatial framework that gets expanded. Also, time gets ever slower form the perspective of the outside obeserver, but, again, I live in that timeframe, so from my perspective it will take me forever to fall into the black hole. So for me nothing changes (right?). Except that I see everything around me moving away from me. Hold on, I thought, couldn't that explain the aforementioned phenomenon? What if we are caught in a collapsing (part of the) universe? But then I realised that as things are further away they will accelerate away ever faster. And acceleration is not what happened, right? Stuck again.

Until a few years ago someone (Riess or Perlmutter?) discovered that exactly that is the case. When I heard of this I jumped out of my chair. After the initial enthusiasm I didn't know how to present this idea. No-one would take me seriously. Now, finally, I've found a place where knowledgeable people might be bothered to hear me out. So. Any thoughts on this?

By the way, I don't necessarily suggest we're falling into a black hole. I suppose being attracted to anything sizeable enough will have a similar effect. And since everything is attracted to everything else there might not have to be anything special going on. Though if it's that simple I find it unlikely no-one will have thought of this before. Or have they?

Also, as for the other two bases for the Big Bang theory, I don't have an explanation for the background radiation. The abundance of light elements suggests a fairly 'young' universe, which would still be possible if we're in the middle of the Big Crunch. DirkvdM 09:26, 24 September 2005 (UTC)

armed forces transport

can you please tell me where i could find information on the modes of transport the armed forces use?

Are you interested in a specific country's armed forces, or armed forces in general?

If you're interested in a specific country, you might consider going to that country's page and using the military links from there; for instance, for the United States you'll probably browse from there to the Department of Defense page and then the pages for the individual services. From each of those, you might get a list of vehicles, for instance the United States Air Force link has a link to a page called List of military aircraft of the United States.

If you're interested in this topic in general, the United States is still probably a good area to explore, as the US military has logistics capabilities unrivalled by any other military force. --Robert Merkel 10:29, 24 September 2005 (UTC)

gravitation ????

Hello:

Why is it that only one side of the moon always faces earth? If you take an apple and rotate it around a lamp you'll find of you keep the axis facing the same direction all parts of the orange will be reflected as it revolves around the lamp. But the moon has to slowly rotate in such a way that it keeps its one side visible to the earth and as far I can tell it has been showing the same side of the moon for thousands of years? This can't possibly be a coincedence, but I don't see how Newtonian laws of gravity apply to this question.

Will Sperry Kunming China

Will: It's because of tidal forces and friction.

To begin with, do you understand why the ocean has tides? The Moon pulls a bit more on the water close to it, than it does on the Earth as a whole. So there is a bulge of water on the side of the Earth nearest the Moon. Similarly, the Moon pulls harder on the Earth as a whole than on the water far from it. So the Earth gets pulled away from the farthest ocean, resulting in another bulge of water on the side of the Earth opposite the Moon. And that is why we get high tides during the full & new Moon (or nearly so; the land gets in the way of water flow, which makes it all a good deal more complex).

Now, the Earth pulls the same way on the Moon, "trying" to create a bulge on the near & far sides if the Moon. This has two effects. First, if the Moon didn't always show the same face to the Earth, then as it rotated, it would get squashed in various directions. The resulting friction would turn part of its rotational energy into heat, thus slowing its rotation (relative to the Earth). Second, if the Moon is not a perfect sphere, it would have a tendency to settle in a position in which the bulge(s) faced either toward or away from the Earth.

And that is what happened. The Moon is not a perfect sphere, tidal friction slowed it's rotation, and it settled in a position in which the bulges are aligned toward/away from the Earth.

Of course, similar logic would suggest that the Earth should always present the same face toward the Moon. Why doesn't it? First, the Earth is bigger, so it has more angular momentum to keep it going. Second, the Moon is smaller, so there is less tidal force to slow the Earth down. But if we wait long enough, and no other factors intervene, and the Moon stays in its current orbit, etc. (which won't happen), then the Earth should eventually present the same face to the Moon all the time.

— Nowhither 11:21, 24 September 2005 (UTC)

Why would there be a specific bulge? (Maybe)Once upon time, millions of years ago, was the moon rotating around an axis and the earth's gravity finally slowed it down, to its current rotation? And why would friction effect the moon when it is in space where there is no friction? The tide analogy seems obvious because of the fluidity of water, but the solidity of the moon would seem to make a bulge less of a factor as the tides are effected by the moon. Over millions of years do these factors create slight changes that finally effect a final result?

Will Sperry Kunming China

Will, there is indeed friction in space; the laws of physics aren't somehow different in orbit around the earth. You're correct in that there's no air resistance (space being close enough to a vacuum for all practical purposes) but there is still internal friction within the moon. You can demonstrate friction inside solid objects be bending a paper clip back and forth until it breaks, and noting that the metal near the breaking point becomes warm. Similarly, friction within the moon's core can lower its kinetic energy. But yes, it seems plausible that the moon was at one point rotating at a different speed. --David Wahler (talk) 16:09, 24 September 2005 (UTC)

I thought this was a freak thing, caused by an uneven distribution of the matter inside the moon or a violent thing happening to the moon in its past, such as it tearing away from the Earth. The moon article states that the most accepted theory is that just that happened, caused by an impact by some third big object. However, the same section supports the above theory. But then this should also have happened to other moons. Is that the case? DirkvdM 19:04, 24 September 2005 (UTC)

DirkvdM: Yes, most of the known moons in the solar system are tidally locked. See Tidal locking. — Nowhither 19:57, 25 September 2005 (UTC)

It's called Tidal lock. The theory is, eventually every orbiting body becomes tidal locked to its parent body over time. Even the Earth to the Sun. - Cobra Ky (talk, contribs) 19:08, 24 September 2005 (UTC)

Drawing electrical circuits

Are there any freeware or shareware programs available for preparing diagrams of electrical circuits? I can't find any reference to them in the relevant articles. Physchim62 11:02, 24 September 2005 (UTC)

A search for "circuit" at Freshmeat.net turns up a number of packages. I haven't tried any of them myself (though I'm probably about to as an amateur PIC programmer). --Robert Merkel 12:19, 24 September 2005 (UTC)

Check this out at Wikisophia. Lots of other goodies there too which you might find useful. --HappyCamper 13:09, 24 September 2005 (UTC)

EAGLE is one I've used, which has the notable feature of being able to automatically lay out circuit boards for fabrication. (Not sure if that's something you need, but you might want to give it a look.) --David Wahler (talk) 15:57, 24 September 2005 (UTC)

Pause Break

On my QWERTY keyboard, what does the button "Pause/Break" do? --Dangherous 11:10, 24 September 2005 (UTC)

There is a brief explanation on IBM PC keyboard. These days, it's not used very much (except by gamers). --Robert Merkel 12:16, 24 September 2005 (UTC)

optical computing

What is optical computing? How does it work? What are its applications(please mention any brands or products already in use)?

Did you try reading our optical computer article? --Robert Merkel 12:09, 24 September 2005 (UTC)

md5 status?

What's the current status of the md5 hashing algorithm? There are numerous attacks noted against it, but would it be possible to easily explain what is possible and what not? And will sha-1 have the same problems soon? Thanks

Assuming you've read Md5#Practical_effect_of_cryptanalysis and find it unclear, what it's saying is that it is possible and fairly easy to construct two different inputs which result in the same MD5 hash value - however the currently known methods for doing this do not generalize to finding a second input that results in the same hash value as an arbitrary given first input. MD5 is often used as a checksum to "guarantee" the validity of downloadable software files. This weakness does not mean it's easy for someone to generate an alternate version of an arbitrary downloadable with the same MD5 hash. What it does mean is that if I have full control over the downloadable file, I might be able to create two versions that have the same hash value. MD5 is also often used as a mechanism to store or transmit passwords. The MD5 article does not mention this, but modern processors are fast enough to compute the MD5 value for all possible, fairly short (8 characters or less), inputs which means if I can access the MD5 hash value for your password and you have a fairly short password, I can find out what your password is. This is one reason users are often told to use long passwords. There are some theoretical weaknesses in SHA-1, but no currently known method for "fairly easily" generating two different inputs with the same SHA-1 hash value. SHA-1 also takes long enough to compute that a brute force attack on passwords is only possible for shorter passwords. -- Rick Block (talk) 14:56, 24 September 2005 (UTC)

How to produce endorphin

(no question)

1. Laugh.

2. Enjoy.

--Sum0 17:51, 24 September 2005 (UTC)

-2 Stick your hand in a bees' nest

-1 Whip yourself with nettles

0 run a marathon

Tonywalton  | Talk 00:48, 25 September 2005 (UTC)

Alternator wire

what is the maximun voltage drop allowed on an alternator wire on a vehicle
(added header to question - Mgm|^(talk) 14:22, 24 September 2005 (UTC))

I assume you mean "allowed by law". I imagine that would vary from country to country. You might want to indicate what country you are referring to? (In any case, I don't know the answer.) — Nowhither 20:01, 25 September 2005 (UTC)

Roentgenium's Color

If we could somehow produce enough Roentgenium to be visible to the naked eye (ignoring decay), what color would it be?

Probably silver-gray in colour. From its electron configuration, it will behave as a metal. With few exceptions, that's the colour that you get. TenOfAllTrades(talk) 17:33, 24 September 2005 (UTC)

Storage size

What is the storage size of a hard disk, Tape, CD-ROM,CD recordable and a DVD please can someone answer this one asap

Sounds like homework, but since it's so simple: with publicly available drives up to at least 2TB (although this is an external drive), up to 800GB, 650-700MB, 650-700MB, and 4.7GB (8.5 for a dual layer disc), respectively. For #3 and #4, larger variants DO exist, but they are fairly rare, and for #5, the capacity is twice as much for dual-sided discs. --Pidgeot (t) (c) (e) 17:28, 24 September 2005 (UTC)

It is related to the hardware ability to store & get at stuff in very small sizes (IBM has a quantum computer which records data at an atomic level, but this is still laboratory technology) and the addressing scheme. I think that 64-bit is pretty much the standard in what is economically available, but IBM reputedly has 128-bit in testing. AlMac|^(talk) 18:46, 24 September 2005 (UTC)

Who discovered the treatment of Malaria?

See malaria. — mendel ☎ 22:36, 24 September 2005 (UTC)

How much does 7 liters of gasoline weigh?

Could someone who remembers more of high school chemistry tell me how much 7 liters of liquid gasoline weighs? Either metric or imperial, doesn't matter. Thanks. --Brasswatchman 20:09, 24 September 2005 (UTC)

• Depends on the type of gasoline. Is it leaded or unleaded? High or low octane? Gasoline is usually a mixture of different components and the composition can differ per produced batch. I'm afraid giving a single answer is going to be quite difficult. - Mgm|^(talk) 20:19, 24 September 2005 (UTC)

• Our density article say gasoline's density is 0.73 g cm^-3. (I assume that's an average value, seems to match the value I got from a quick google). 7 litres is 7000 cm^3, so it would weigh 7000 * 0.73 = 5110 g or 5.11 kg. -- Bob Mellish 20:32, 24 September 2005 (UTC)

• I wasn't looking for anything exact, just average. Great. Thanks, both of you. Brasswatchman 9:53 PM EST, 24 September 2005.

Stanisław Ulam

How is Ulam pronounced - You-lam or Uh-lam ? Tintin 20:54, 24 September 2005 (UTC)

I've always used the latter, but I can't say if that's correct or not... Shimgray 20:55, 24 September 2005 (UTC)

According to Polish language, it would be more like Oo-lam. Physchim62 21:06, 24 September 2005 (UTC)

Yes, Oo-lam. Stan-iss-wav Oo-lam. I don't know what that is in IPA. Proto t c 13:09, 26 September 2005 (UTC)

Help me begin understanding Prolog...

Since my professor doesn't seem to intend on replying to my e-mail (this is not a homework assignment, but I have to understand the basics of this silly language in less than 10 days before the first test), I'll throw this question to fellow Wikipedians, whom I hope some know Prolog.

Given this file:

line(2, 2, 4, 5).
line(1, 2, 4, 5).
line(1, 1, 4, 4).

linelen(line(X1, Y1, X2, Y2), Z) :- DX is (X2 - X1)**2, DY is (Y2 - Y1)**2, sqrt(DX + DY, Z).

I am able to do this:

?- linelen(line(1, 5, 3, 6), Z).

And get a valid result for Z. However, if I attempt pattern-matching:

?- linelen(line(A, B, C, D), Z). or ?- linelen(L, Z). It gives me ERROR: Arguments are not sufficiently instantiated. (I've also tried all sorts of other things, all of which give me this error -- this is the most basic, though, where I began trying to write this function).

Why is it not pattern-matching? I expected it to give me the lengths of each line that I declared as previous facts, but for some reason, it is not doing this. Is there something I'm not understanding right about how pattern matching works in Prolog? I think I understand it pretty fine, but it's the syntax that seems to be killing me. What would be the "correct" way to implement this function?

Also, could anyone recommend a really good book about Prolog? Our course textbook is the one written by Mr. Ivan Bratko, who I understand had a hand in standardizing Prolog, but unfortunately it's not really that good a textbook when it comes to explaining things clearly. A good example of a programming language manual that "clicks" with me is the one for Lua written by Roberto Ieruschamily(sp?) -- are there any Prolog books like that out there? --I am not good at running 00:22, 25 September 2005 (UTC)

It's been a while since I've worked with prolog, but I think your problem is that line(A, B, C, D) is returning false. Prolog only knows what you tell it, so if I for instance wrote a program:

related(marge, lisa).
related(marge, bart).
related(marge, selma).
related(snowball II, snowball III).

Then I'm simply telling it that all the above three statements are true. So if I input related(selma, bart), it'll return true while related(snowball II, lisa) will return false. Or if I input related(selma, Z), it'll return one of marge, lisa, or bart as Z.

So your first three lines are doing exactly what I did above, only nowhere in there is there A, B, C, D, so line(A, B, C, D) will always be false. What I think you want is to cut your entire program down to:

 linelen(X1, Y1, X2, Y2, Z) :- DX is (X2 - X1)**2, DY is (Y2 - Y1)**2, sqrt(DX + DY, Z).

Like I said, it's been a while, but hopefully that helps. — Laura Scudder | Talk 00:40, 25 September 2005 (UTC)

Awesome, that seems to work. I had to do this on the query line though: ?- line(A, B, C, D), linelen(A, B, C, D, Z).. I didn't know that query lines could contain comma-delimited multiple phrases (I thought only rules could) but it seems to work, in fact be required to get it working right. Thanks! --I am not good at running 01:21, 25 September 2005 (UTC)

I think the other way to do this would be to match one of the facts in your fact base before doing the arithmetic computation as part of the linelen definition, i.e. I think linelen could be:

linelen(line(X1, Y1, X2, Y2), Z) :- line(X1,Y1,X2,Y2), DX is (X2 - X1)**2, DY is (Y2 - Y1)**2, sqrt(DX + DY, Z).

The issue is the computations cannot be done on uninstantiated variables (could be if you defined your own version of the operators using facts from the factbase). The key is you have to make sure any variables you're doing arithmetic on are instantiated to actual values at some point before you try to do the arithmetic. I learned Prolog from the Clocksin and Mellish book (a long time ago). -- Rick Block (talk) 16:41, 25 September 2005 (UTC)

Hmm that approach seems to give neater-looking results when going for an entire series of defined line(etc, etc, etc, etc). facts, but it doesn't seem to be as flexible beyond that. I rewrote my linelen as per your example, but now it only seems to allow pre-defined lines, and answers "No." for arbitrary arguments. example:

?- linelen(A, Z).

A = line(2, 2, 4, 5)

Z = 3.60555 ;

A = line(1, 2, 4, 5)

Z = 4.24264 ;

A = line(1, 0, 4, 4)

Z = 5 ;

A = line(-5, 7, 1, 10)

Z = 6.7082 ;

A = line(10, 0, 39, 60)

Z = 66.6408 ;

No

?- linelen(line(2, 7, 320, -4), Z).

No

I definitely have a better understanding of how Prolog matches patterns now than I did two days ago, especially as to how it behaves when arguments are instantiated in the definition vs. being instantiated in the query lines before the actual function. Can't wait til I get around to tinkering with cuts and fails :) --I am not good at running 19:47, 25 September 2005 (UTC)

gravity

what is gravity, how does it act on mass. D Armstrong

The answer to these questions get quite complex and philosophical; see gravity for some discussion. There are two standard theories of gravity: Newton's law of universal gravitation, which for predictive purposes is almost always "close enough", and general relativity, which can provide predictive answers in those relatively few situations where Newton's laws give slightly incorrect answers. However, general relativity is incompatible with quantum mechanics, which is our model for understanding the other fundamental forces of the universe acting at a very small scale. Therefore, our understanding of the fundamental forces of the universe is incomplete; the models we have are incomplete approximations. So ultimately, we don't really know what gravity "really" is, but we have models that can predict what it will do. But what does it mean to know what gravity "is", anyway?

Aren't you glad you asked? --Robert Merkel 03:47, 25 September 2005 (UTC)

Also see Intelligent Falling :) -- Rick Block (talk) 04:27, 25 September 2005 (UTC)

how to handle demand of medical services

Find out what the United States is doing, and do the opposite...more seriously, if I'm understanding your question correctly you might be well served by starting with our (brief) article on heatlh economics health economics, health maintenance organization, managed care, and linked articles. No country is particularly effective at handling this problem; that is, unless you take the view that the ability to pay is the proper and only criterion for determining how medical treatment should be allocated. --Robert Merkel 12:10, 25 September 2005 (UTC)

military

i have to do a presentation on how to decrease cost of military?

Firstly, I'm assuming you're American. If you're not, recalibrate this advice to specifically search for items related to your country...anyway...

Do your own homework, but have you considered doing a Google search for, say, "defense budget waste" and seen what comes up? Tried a similar search on an electronic newspaper archive, if your educational institution has access to one? Oh, and just because I'm feeling super-generous, here's one big hint: missile defence... --Robert Merkel 04:03, 25 September 2005 (UTC)

Less wars. Ojw 10:41, 25 September 2005 (UTC)

media

How to protect people from media?

You could lock them in a room with no televisions, radios, magazines, books, internet access, etc… Not sure why you would want to do this, though. Perhaps your question could use some clarification? Garrett Albright 10:30, 25 September 2005 (UTC)

multinational organization

How to hsndle problems created by big and large multinational organization?

• That depends entirely on the problem and the organization in question. Please be more specific. If you are unhappy with a product or service provided by a large organization, try writing a letter of complaint. - Mgm|^(talk) 07:49, 25 September 2005 (UTC)

Determinants

In my far younger days, when I was but a lad running through the meadows and marvelling at the glory of the morning dew, I briefly studied some matrix-theory. Alas, those days are long gone now, and what very little I learnt has mostly been passed into the forgotten lore-section of the library that is my memory.

Now, however, I'm going to need a little help with determinants, don't ask me why :P Our article Determinants is not totally clear on this issue (ie. it's probably perfectly clear and I'm an idiot, anyway I intend to clear it up a bit if I get a satisfactory answer here)

I remember this much: If you want the determinant of a 2d-matrix you go

${\begin{vmatrix}a&b\\c&d\end{vmatrix}}=ad-bc$

And for three dimensions you go:

${\begin{vmatrix}a&b&c\\d&e&f\\g&h&i\end{vmatrix}}=a{\begin{vmatrix}e&f\\h&i\end{vmatrix}}-b{\begin{vmatrix}d&f\\g&i\end{vmatrix}}+c{\begin{vmatrix}d&e\\g&h\end{vmatrix}}$

So far so good, right? My question is, does this extend to higher dimensions? That is, would the determinant of a 4d-matrix be:

${\begin{vmatrix}a&b&c&d\\e&f&g&h\\i&j&k&l\\m&n&o&p\end{vmatrix}}=a{\begin{vmatrix}f&g&h\\j&k&l\\n&o&p\end{vmatrix}}-b{\begin{vmatrix}e&g&h\\i&k&l\\m&o&p\end{vmatrix}}+c{\begin{vmatrix}e&f&h\\i&j&l\\m&n&p\end{vmatrix}}-d{\begin{vmatrix}e&f&g\\i&j&k\\m&n&o\end{vmatrix}}$

This seems fairly trivial, but i felt it would smart to ask. Ohh, and by the way, marvel at my l33t TeX sk11lz! gkhan 05:20, 25 September 2005 (UTC)

Very good, your evaluation of the determinant is correct. Remember that you can expand along any row or column as well as the first row. Enochlau 11:57, 25 September 2005 (UTC)

But mind the changes in sign! ${\begin{vmatrix}+&-&+&-&...\\-&+&-&+&...\\+&-&+&-&...\\-&+&-&+&...\\...&...&...&...&...\end{vmatrix}}$ --R.Koot 19:11, 25 September 2005 (UTC)

gkhan: You should know that determinants, while being a useful theoretical tool, essentially never need to be computed. If you are simply curious about this, then that's fine. If you are interested in learning about how determinants fit into matrix theory, no problem. But if you have some practical computation for which you think you need to compute the determinant of a large matrix, then I would advise you that there are probably better ways to do your computation. — Nowhither 20:08, 25 September 2005 (UTC)

Yes, I realise that :P I'm simply curious, if I ever need to compute it, I'll use Mathematica :P gkhan 22:13, 25 September 2005 (UTC)

Places where the pressure change most obvious in one day

Is there any place where the atmosphere pressure at that place would change very obvious in a day?Could it be beaches?

The most atmopsheric pressure changes during a short period of time is when a strong tropical cyclone is approaching, preferably at a high rate of speed. For example, atmospheric pressure bottomed out in hurricane Rita at 917 mb I believe while the worldwide average is 1014 mb. -Drdisque 06:12, 25 September 2005 (UTC)

• Do aeroplanes count? BTW, I heard a figure for 897 mbar for the minimum of Rita: the standard atmospheric pressure is 1013.25 mbar. Physchim62 10:05, 25 September 2005 (UTC)

Information Technology Spending Patterns by Activity Sector

Hello,

As part of my Executive MBA Programme, I am examiniing Information Technology Spending Patterns by Activity Sector.

Would anybody have any sources, articles that have looked at this question in detail? I am particularly interested in the Finance, Retail and Manaufacturing Industries and in the Europe, Middle East and African region,

Thanks

Seanjoseph

--Seanjoseph 10:28, 25 September 2005 (UTC)

Dr. Salam's Nobel Prize

what was the theory of Dr. Salam, for which he was awarded Nobel Prize in 1979 ?

See Nobel Prize in Physics. The prize was given "for their contributions to the theory of the unified weak and electromagnetic interaction between elementary particles, including, inter alia, the prediction of the weak neutral current", so it looks like he was one of the co-creators of the electroweak theory. Our article on that isn't very helpful, though... Shimgray 11:45, 25 September 2005 (UTC)

Hurricanes - how are the formed and where?

How are hurricanes formed, and where do they begin? Apart fro the western US do other arts opf the world get hurricanes? e.g. S. America, Europe, Africa, Asia? Signed Sarah B

• See Hurricane. --jpgordon∇∆∇∆ 15:02, 25 September 2005 (UTC)
• Our Tropical cyclone article is worth a look too as that is what they are called in northern Australia. Capitalistroadster

question plz

can you tell me how water can be purified by sand gravel and pebbles or can it be only purified by sand and gravel, not pebbles. plz answer me back as soon as possible. i need to give as much information as i can to my teacher tomorrow</math>

• Just pebbles isn't enough. They will only filter out the biggest things out. Our article on Water purification may be of use to you. - Mgm|^(talk) 20:01, 25 September 2005 (UTC)

Breath Waste products

What two waste products are contained in your breath?

• Is this, by any chance, a homework question? Notinasnaid 19:26, 25 September 2005 (UTC)
• I'm by no means an expert on anything biological so don't take my word for this, but sometimes the tonsils (or whatever those two holes in the back of your throat are) will develop thick gobs of pus -- white blood cells, I think -- causing a really horrible odor in your breath. I usually get this when I have a cold and sore throat. I wouldn't be surprised if this were one of them, considering it's gross as hell like you'd expect from a "waste product", so look into that and see if it's true --I am not good at running
• Don't forget good ol' Carbon Dioxide.--inks 20:47, 25 September 2005 (UTC)
• air - oxygen = carbon dioxide + nitrogen. --R.Koot 21:01, 25 September 2005 (UTC)

education

demographic educational levels in spain?

Iron Supplements & Dental Caries

Does Supplementary Iron drops in childrens cause dental caries? ---~~|

As a molecular-biologist-in-training, I would be surprised if they did. Have you tried searching with those terms on Pubmed? [11] --inks 02:18, 26 September 2005 (UTC)

The Color Spectrum

When was the Optical Color Spectrum founded? Who dicovered the wavelengths and in what year did the factual evidence occur?

Isaac Newton discovered the spectrum (I belive he discovered it in his anno mirabilis, 1666), although he thought light was made of particles (which it turns out it kinda is, and well, kinda isn't). The first to surmise that light was made from wavelengths I'm pretty sure was Thomas Young using his double-slit experiment in 1801. By the way, that experiment, it's ridiculusly cool. What do you mean by factual evidence? Both Newton and Young had factual evidence (Newton saw the spectrum, Young saw the wave-interference). For more info, see Optical spectrum gkhan 03:27, 26 September 2005 (UTC)

Well, Newton recognised the spectrum for what it was. After all, the spectrum is shown in things like the rainbow, so the first person to notice that is lost in the mists of time. --Fangz 12:49, 26 September 2005 (UTC)

How many fault lines are there

A whole bunch. Each boundary lines is a geologic fault, but according to the article, there are a whole mess of faults that are nowhere near any tectonic plate-boundaries. gkhan 03:34, 26 September 2005 (UTC)

Gravity and its effect on the human body

Hi Science Wizards; My question is ,does Gravity have any measurable effects on the human body and if so how are these effects measured ? Does gravity effect the body different at night then during the day ? Are its effects different if we are standing or lying down?

                                    Thank you , this site is great ,Sincerely Dennis NIgrelli

Gravity has many effects on the human body. Off the top of my head, I can think of how the fluid pressure in the feet is higher than in the head when you're standing, thus the need to elevate the feet for many medical problems. Another issue is that gravity causes the pressure and stresses in you're skeletal system. I know of at least one bio-engineering researcher studying how to grow artificial menisci who has discovered that to grow them properly, you need to simulate the force on them that would be present in a growing child. You might be interested in the sorts of medical experiments that NASA has performed on its astronauts on how low-gravity environments affect the body, sometimes called space medicine. — Laura Scudder | Talk 04:02, 26 September 2005 (UTC)

(added after Edit conflict, so I might be parroting a little) Does gravity have any effect on the human bodies? Throw yourself off a skyscraper and check ;). That is, earth has a very big effect on the human bodies, it keeps us on the ground. Prolonged abscence of gravity is very harmful for the human body, your bones start to degrade almost instantly. Thats why astronauts has to be carried off their shuttles. Night and day or standing or lying down has no effect, the only thing that affets gravity is mass of the two objects (in this case, your bodymass and the mass of the earth) and distance to center of gravity (=center of earth). There is however a noticable difference in weight (note:weight, not mass) is if you are closer to the equator. At the equator, you are farther from the center of the earth (since earth isn't a perfect sphere) and you are influenced by the centrifugal force of the rotating earth. I've heard that it's a few Newtons difference from Sweden where I live (which would translate to a few hundred grams). gkhan 04:08, 26 September 2005 (UTC)

In case you are not enrolled in a space program, I've heard (although couldn't find it in Wikipedia, so it could be urban myth) that your spinal disks compress during the day due to gravity, so that at the end of the day you are a couple of centimetres shorter than you are after a nights rest (when you are horizontal your disks can expand). --Commander Keane 06:41, 26 September 2005 (UTC)

Another aspect of gravity affecting the human body is its effect on those subject to high-G, for example fighter pilots. A high-G turn can cause the pilot to lose vision and eventually consciousness. They wear special suits, G-suits, to help protect against it. Which brings me to the other point. There is no difference between the effect of G at night or day, but it does make a difference if you are lying down or not. You are less prone to blackout if you are lying down. DJ Clayworth 17:08, 26 September 2005 (UTC)

Heat suits and ambient vs. radiant heat

This crazy moon-man suit protects the wearer from 1500°F ambient heat and 2000°F radiant heat. This less-crazy moon-man suit still maintains 2000°F radiant heat, but only 200°F ambient. What do they mean by "ambient" and "radiant" heat? What sort of things would one need a 2000°F/200°F suit for? I read over Heat and Thermal radiation and understand what thermal radiation is, but I can't figure it out in terms of those suits. (Not that I need to know for any practical reason, but it's bugging me that it's not obvious to me.) — mendel ☎ 04:46, 26 September 2005 (UTC)

As I understand it, ambient heat is the temperature of air in a location, and radiant heat is the temperature to which a solid body in that location would be raised to by the thermal radiation. You can reflect thermal radiation, but you can't "reflect" the ambient temperature, so it's not surprising that it's much easier to protect against radiant than ambient heat. --Robert Merkel 05:47, 26 September 2005 (UTC)

Oh, and this page on that website says pretty much the same thing I just did. --Robert Merkel 05:50, 26 September 2005 (UTC)

I must have read right past that section, thanks. I'm now thinking about "1500° in the shade!" — mendel ☎ 19:16, 26 September 2005 (UTC)

Computer Safety - list of free mp3s

Through a site I trust (a wiki no less!) I discovered something called Webjay which appears, according to its newbie FAQ, to offer playlists of free mp3s compiled by users who simply link directly to external legal mp3 files, (eg this playlist of tracks John Peel is supposed to have played).

I've never previously been scared of mp3 files. As far as my knowledge goes, mp3 files are not a security risk to my machine. But, I suppose this just seems a little too good to be true ;o) My question is, simply, is it safe?

Whilst I'm here, what do Wikipedian Windows users use for anti-virus software? I have always used Norton, but due to some of the ways I've been using my machine lately I've come to share the seemingly prevalent view that Norton slows down your system. --bodnotbod 06:24, 26 September 2005 (UTC)

The corporate versions of Symantec anti-virus are less resource-hungry than the consumer versions. I don't know why. I run Symantec Client Security on my Windows machines. I don't know if a consumer can buy it - I got it for free from work before I left. I've heard AVG is quite reasonable and it's free for non-commercial use.-gadfium 06:47, 26 September 2005 (UTC)

I would be very surprised if a .mp3 or .m3u file posed a security risk in itself (of course, you can rename any file to a .mp3/m3u). ATM, I don't run any anti-virus software, and have not for a few years. Then again, I don't use MS Outlook either :)--inks 10:49, 26 September 2005 (UTC)

I recall hearing about some programs that had a security error with ID3 tags, allowing a buffer overflow. I don't believe it's a threat if you use an updated player, though, like Winamp 5.10.

As for anti-virus, AVG is a very good program. Not to mention free. ^_~ --Pidgeot (t) (c) (e) 11:08, 26 September 2005 (UTC)

• At the moment I run a free version of AVG anti virus. - Mgm|^(talk) 08:06, 26 September 2005 (UTC)
  • At home I run AVG free on my laptop and AVG paid-for on my main PC. The main benefit of the paid-for version is the customisability (if there is such a word) of the tests and test/update scheduling. Unless you want to fiddle with settings and the like then the free version is more than adequate. Thryduulf 14:24, 26 September 2005 (UTC)
    • Well, that's quite a vote of confidence in AVG. I too am pretty good, I believe, in terms of surfing safely and did manage not to get any nasties for years without running any guard at all. The only thing that's stopping me dumping Norton immediately is that - if I recall correctly - I only PAID to renew my subscription about 4 months ago. But I've already lost the money and there's no point being a damn fool about using a slowed computer unnecessarily, I suppose. --bodnotbod 01:32, 27 September 2005 (UTC)

Hurricanes

Dear Sirs,

I am currious to know if the water picked up over the ocean by a hurricane and is later dropped over land, is salt water or fresh water when it hits the ground? How does the hurricane suck the water up and if the rain droped is fresh, where does the salt go? Does the salt stay in the Ocean because it is too heavy or does it evaporate during the picking up of the moisture process? --[User:24.58.206.102|24.58.206.102]] 14:02, 26 September 2005 (UTC)

First, please do not indent text by pleaving blanks at the start of paragraphs on wikipedia. it formats your text as mon-spaced, unwrpped, which is good for a few special purposes, but not for ordinary text.

Secxond, the water evaporates from the ocean surface and joins the hurricane as water vapor. This leaves the salt (and anything else dissolved) behind. Thus any rain is fresh water. DES ^(talk) 14:13, 26 September 2005 (UTC)

Computers Solving Mathamatical Problems

Do mathamagicians accept that computers can solve very complex problems?

for example. The four colour map theory has been solved by computers for a massive ammounts of polygons. However, many people still say that it has never been solved as a computer did it.

I dont get it! Please help

While it has been proven, many mathematicians find an exhaustive search so unelagant they don't want to call the verification of all posibilities a proof. One very good reason is that such a search does not give provide a deeper insight in why this it is true, which is often considered more important than the fact that it is true (see four color theorem). Also, most problems cannot be solved in this way, because an infinite number of cases have to be tested, or an amount simply too large. For example, the weak goldbach conjecture. Also if we would be able to lower this bound so that we could do a computer search, this would be rather pointless as the conjecture is of no practical use and a computer search would provide no intellectual challence. --R.Koot 14:22, 26 September 2005 (UTC)

The various computer-assisted proofs of the four color theorem are examples of a method of mathematical proof called proof by exhaustion. A computer-assisted proof by exhaustion involves the following steps:

1. Show that a problem can be reduced to solving a finite (although possibly very large) number of special cases
2. Devise a method of solving any one of these special cases through a finite (though again possibly very large) number of calculations
3. Write a computer program to apply this method to each of the special cases, with cross-checks to detect mistakes in design or programming or run-time errors
4. Run the program
5. Publish the program, the results and an explanation of the method in an accessible form.

Only step 4 is actually carried out by the computer. The reservations that some mathematicians might have about such proofs are more to do with the difficulty of completely validating any long and complex proof, and the lack of insight inherent in the proof by exhaustion method, rather than the fact that a computer has been used. Gandalf61 14:44, 26 September 2005 (UTC)

Original poster: You have perhaps been reading some out-of-date information.

It is true that we are not very happy with large computer-based proofs, because they are not very elegant and they give us little insight into what is really going on. Further, they force us to base notions of absolute truth on whether some particular electronic circuits were functioning properly.

However, the most important problem with the mid-1970s Appel-Haken-Koch proof of the Four Color Theorem is that no one has ever checked it independently. A group of researchers (Robertson, Sanders, Semour, Thomas) decided to do the checking in the early 1990s. They eventually found it easier to produce their own computer-aided proof, which followed similar lines, although it was a bit simpler. This proof has been checked independently. Further, you can download their program and run it yourself.

So now we can be quite confident that we do have a proof of the Four Color Theorem. And mainstream mathematical culture generally accepts computer-aided proofs these days. Although we still prefer traditional proofs, for the reasons of elegance and insight that I mentioned above.

— Nowhither 18:04, 26 September 2005 (UTC)

what is the freezing temperature of alcohol?

Does alcohol freeze as how water would freeze? If so what temperature does it freeze at?

There are many different kinds of alcohol, and they all have lower freezing (and boiling) points compared to water, which freezes at 0°C, or 32 F. The one you're probably thinking of is ethanol, which is the alcohol in alcoholic drinks. In normal atmospheric conditions, ethanol freezes, in much the same manner as water, at -114.3 °C, or -173.74 F. Proto t c 15:08, 26 September 2005 (UTC)

A minor nitpick...the low molecular weight alcohols freeze and boil at much lower temperatures than water; the longer chain ones freeze and boil and higher temperatures. Methanol (one carbon), ethanol (two carbons), isopropanol (rubbing alcohol, three carbons) are short chain alcohols. By the time you get out to dodecanol (also called lauryl alcohol) you're up to twelve carbons, and the stuff freezes and boils at 24°C and 260°C, respectively. TenOfAllTrades(talk) 16:16, 26 September 2005 (UTC)

Andrew C. von Eschenbach

What is his biography?

See Andrew von Eschenbach. TenOfAllTrades(talk) 16:06, 26 September 2005 (UTC)

Computer storage media

What are 5 different storage medias with their descriptions, capacity levels, advantages, and disadvantages? Where did you get this information? --63.199.33.66 16:40, 26 September 2005 (UTC)

Please refer to the instructions at the top of the page, and note that Wikipedia is not here to do your homework for you. I would recommend starting at our article on data storage devices, and working from there to find the information that you need. TenOfAllTrades(talk) 16:51, 26 September 2005 (UTC)

DYOH, but a similar question was answered above at #Storage size. Garrett Albright 19:21, 26 September 2005 (UTC)

diseases?

what is the difference between a communicable disease and a pathogenic disease?

• Pathogenic diseases are caused by pathogens (outside sources) while communicable diseases are diseases that can be transmitted between individuals. Most diseases that are communicable are caused by pathogens, but not all pathogenic diseases can be transmitted.- Mgm|^(talk) 22:06, 26 September 2005 (UTC)

Next round of the endless Moth Identification Game

My friend is keen to have this moth (right) identified, which he describes as "huge". Any takers?

File:Reeses huge unidentimoth.jpg

I'm suffering from an identity chrysalis

--bodnotbod 18:57, 26 September 2005 (UTC)

orcas

Hi. Are the Orcas in the fiords of Norway there yet? Thanks.

permutation cipher

• See Permutation cipher. - Mgm|^(talk) 22:08, 26 September 2005 (UTC)

What is the purpose in standards of wiring?

The subject pretty much sums up the question.

Why do you ask? You see, the way you ask it makes it sound a bit like a homework question. Notinasnaid 19:53, 26 September 2005 (UTC)

what is dual axle white balance

I'm assuming you meand "dual axis". Color temperature provides a hint: "Color temperature" is sometimes used loosely to mean "white balance" or "white point". Notice that color temperature has only one degree of freedom, whereas white balance has two (R-Y and B-Y).. So I'd guess (never having seen the expression before, and only coming up with a single Google hit) that simpler cameras use a one-dimensional adjustment (color temperature), calling it "white balance"; while fancier ones (like the Canon EOS series, the only context in which Google found something) have a two-dimensional adjustment. --jpgordon∇∆∇∆ 22:22, 26 September 2005 (UTC)

Space

How did the space program come to in the US after world war 2?

-jody

• Perhaps our NASA article can help you find some answers. - Mgm|^(talk) 22:11, 26 September 2005 (UTC)

• The program to get German rocket scientists (and, indeed, rockets) out of Germany was known as Operation Paperclip. Shimgray | talk | 23:28, 26 September 2005 (UTC)

Chemistry

Dear Chemists:

I need to know exactly how much HCL acid and distilled water to combine to arrive at a liter of 1.5M solution of dilute HCL acid. Note: I am using 31.45% Muriatic acid for this project. If possible, please tell me how you arrive at the answer.

Thank you in advance! Docfrickey

Let me try. From Hydrochloric Acid (which is Muriatic acid by a different name), we know that HCL is 36.46 g/mol. For 1L containing 1.5M, you need 36.45*1.5=54.675g. A 31.45% solution of HCL has 31.45g (or 0.86 mol) of HCL/100ml, so you need 1.5/0.86*100ml=174ml of 31.45% HCL solution. Make up to 1L with 826ml of distilled water. Can someone else check my numbers? I was never very good at this :) --inks 23:18, 26 September 2005 (UTC)

These values of 174ml of 31.45% HCl and 826ml distilled water are correct. You get a solution of exactly 1.5M.Borbrav 05:48, 27 September 2005 (UTC)

• Docfrickey,

I have removed your e-mail address. The response isn't by e-mail and keeping it in such a high-traffic site means you will receive plenty of Spam and Phishing attempts. Capitalistroadster 05:59, 27 September 2005 (UTC)

how much water does asparagus use

How much water does Asparagus use to grow? To cook? To wash his car with? Our article on Asparagus has links at the bottom to websites describing how to grow and cook it, and hopefully one of them contains what you want to know :) --inks 00:35, 27 September 2005 (UTC)

mission critical

Wht does mission critical mean?

It denotes something (or even someone) that is of crucial importance to a particular objective, or mission. Very generally, without a mission critical item, the mission cannot proceed or be completed.--inks 00:44, 27 September 2005 (UTC)

What is this insect?

Long time answerer, first time asker: What is this insect? The photo is from Anza Borrego Desert State Park near San Diego, CA.

red & black bugs eating daisies in the desert

Thanks, --Joel 02:34, 27 September 2005 (UTC)

Lightning?

What is lightning?

Have you seen our article about Lightning? It has some wonderful photos, and explains the phenomenon well.--inks 05:47, 27 September 2005 (UTC)