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April 20

chainmail armour?

how did they make this even before they had metal working tools?Cyoda mackbuy 21:27, 7 April 2006 (UTC) (copied from the archives page, where it was wrongly asked zafiroblue05 | Talk 00:48, 20 April 2006 (UTC))

See chainmail-gadfium 01:37, 20 April 2006 (UTC)

• Very slowly and at great expense. Although in a broad sense, they would have had some metal working tools as soon as they had metal. Even today, making chainmail is expensive and labour-intensive compared to ordinary fabrics. Peter Grey 06:25, 20 April 2006 (UTC)

Fatal Blood Loss

How much blood can a person lose and still survive? At what point (i.e. how many pints or liters, considering normal is ~9 pints or ~5 liters) does blood loss become fatal? KT24.124.51.110 01:16, 20 April 2006 (UTC)

Well, off the top of my head, a hemorrage is any blood loss of more of 500 ml, and our article on bleeding says that after 1 liter lost, it can be fatal. Titoxd^{(?!? - help us)} 03:53, 20 April 2006 (UTC)

"Hemorrhage" refers to any amount of bleeding. How much blood can someone lose and still survive depends on a number of factors: their general health, presence of underlying medical conditions (for example, coronary artery disease, how much blood they started with, and if they receive timely resuscitation or transfusion. - Cybergoth 01:30, 21 April 2006 (UTC)

That'd have to be an exceptional case. Blood donation routinely takes 1 litre, so clearly for most people 1 litre is a safe amount. It sounds like the "drowning in 1 inch of water" ..... possible but unlikely. I would suspect the death point comes when the body cannot compensate for the traumatic loss of blood pressure and either suffers cardiac arrest or loss of brain function leading to unconsciousness and (if unhalted) death. The body also reacts to certain conditions by convulsive constriction of major blood vessels too which may be a factor. FT2 (Talk) 19:31, 26 April 2006 (UTC)

Script for Wikipedia

Is there a script that can change my homepage (using Opera) to the wikipedia page relative to that day? (IE, it's April 20th, therefore my homepage is set to http://en.wikipedia.org/wiki/April_20). I was wondering if one existed, or if this already exists serverside (like a "Special:Date" page that does this). If not, what would be the easiest way to write a script/program to do this? I was thinking of using either Javascript or Java. - BlazeWizard (Not registered) - 3:58 PM.

I believe you can do it if you create a template in your user space that redirects to the page of the date, and there is a variable in mediawiki that gives you the date. Let me check it out.  freshgavinΓΛĿЌ  05:51, 20 April 2006 (UTC)

Like this: User:freshgavin/Sandbox/Redirect to date page. It was much easier than I expected.  freshgavinΓΛĿЌ  05:55, 20 April 2006 (UTC)

That doesn't redirect, though — at least not for me. It seems that mediawiki isn't recognizing the redirect construct and is instead just treating it as a list. — Asbestos | Talk (RFC) 15:45, 20 April 2006 (UTC)

Yeah I noticed that and I was looking through MediaWiki to see why it doesn't recognize it. Apparently in a case like this (it is treated as a special page) redirects are ignored by MediaWiki, even with the ?redirects=yes tag. I'm pretty sure there's no way without JS or bruter, as described below.  freshgavinΓΛĿЌ  07:02, 21 April 2006 (UTC)

Thanks for the replies guys, I did however come to a very simple solution to do this. Simply create my own html page with a javascript that uses my computer's date to generate a url, then redirect to that url. Here:http://en.wikipedia.org/wiki/User:BlazeWizard - BlazeWizard 7:447 20 April 2006 (UTC)

Speed of Light

I actually have two questions:

1) Has any headway been made in the field of quantum physics suggesting that Einstein's assertion that the speed of light is the definitive speed limit that any object can move is no longer accurate? (sorry for the run-on sentence!)

2) This may be a silly question, but bear with me. When at a concert or some other event where "flood lights" are used, it appears to my eye that the lights actually "flood" from there source to their destination. In other words, it appears that I'm witnessing light travel from its source (the flood lights) to its destination (the stage). I'm sure I can't possibly be witnessing the actual speed of light in action. That can't be right. Yet it still appears that the light beam, in a split second, is travelling from its source to its destination. Assuming I'm not actually witnessing the light travel, what optical illusion is at work here?Loomis51 04:18, 20 April 2006 (UTC)

1) It's not an assertion, it's a consequence of certain postulates. (which could be called assertions) It can only be false if A) Nature suddenly starts ignoring the rules of logic we've used to describe it so far (In which case Science is useless and we shoud all just go home) or B) One of the postulates of relativity is false. AFAIK, nothing in QM has invalidated those postulates.

2) Presumably you're just seeing the light intensity increase to its maximum as the bulb gets warmed up. --BluePlatypus 05:17, 20 April 2006 (UTC)

To expand on BluePlatypus' answer to 2), your eye can probably see the bulb (begin to) light up before it is bright enough to (noticeably) spread light to the surrounding surfaces, and your brain fills in the sequence by assuming that the light flows from the bulb (which appeared brightly first) to the surrounding surfaces.  freshgavinΓΛĿЌ  06:33, 20 April 2006 (UTC)

Also... in general, when a light illuminates a distant object you should be able to see only the light itself and the object. You shouldn't see the light passing between. If you do, it's because the light is bouncing off (and illuminating) something between. Outdoors, there is often water vapour in the air. For indoor concerts there may be deliberate smoke or mist for atmosphere. So when a floodlight it turned on, it looks as if you are seeing the light "pass through the air". In some cases the heat of the light will change the character of the things in the air close to them, as well. Notinasnaid 10:57, 20 April 2006 (UTC)

Thanks to all of you for your input. It was very thought provoking. In fact it provoked this follow up question: Suppose there exists one bright star adjacent to a large nebula one light year in width and several hundred light years away from earth. (I know a nebula is obviously a 3D phenomenon so "one light year in width" may appear odd. What I'm suggesting is merely that the light that passes through the nebula from the star would take one year to pass from one side to the other.) Suppose there are no other stars in the vicinity to provide anywhere near as much illumination as the one star mentioned. Now suppose the star goes super-nova. Would we then be able to see the speed of light "in action"? Would the nebula slowly darken, over the course of a year, begining at one side and ending one year later at the other?

One other question: Do there exist any "stray" stars in intergallactic space not belonging to any galaxy?Loomis51 23:23, 23 April 2006 (UTC)

• Yes. They're also called rogue stars or hypervelocity stars. There are also rogue globular clusters. [Note to self: Create rogue star article.] -- Filliam H Muffman 01:35, 25 April 2006 (UTC)
  • There are also stars observed in galaxy clusters that aren't clearly associated with any particular galaxy within it, particularly around the central galaxy but not bound to it. --Bth 11:16, 26 April 2006 (UTC)

Camparison of 1st magnitude star and light bulb

I'm trying to give a someone comparison of brightness. Approximately how far away would a 60-watt light bulb have to be to have the same aparant brightness as a first-magnitude star? Bubba73 (talk), 04:21, 20 April 2006 (UTC)

First of all, as I've recently learned (thanks to Jayant!) wattage is not a measure of brightness, it's a measure of electricity required. Nonetheless, it would appear to me that you could virtually stick the 60-watt bulb in your eye and it still wouldn't compare to the brightness of a first-magnitude star. Loomis51 04:41, 20 April 2006 (UTC)

A first-magnitude star isn't really all that bright, if I'm reading apparent magnitude and absolute magnitude correctly. However, intensity decreases with the square of the radius...that probably factors in somehow. I'm not a physicist, but that's my shot at it. Isopropyl 04:48, 20 April 2006 (UTC)

Right - wattage is the energy used, not the brightness. So suppose the light bulb is 1,000 lumens. How far away would that have to be to have the aparant brightness of a first magnitude star? Bubba73 (talk), 05:19, 20 April 2006 (UTC)

Well, I've found the figures I need to do the calculation, which I'll do tomorrow. Bubba73 (talk), 05:26, 20 April 2006 (UTC)

Since you're giving someone a comparison, why not turn on a 60-watt light bulb, look at it, go outside, and look at a first-magnitude star? I'd recommend Spica from Virgo, or Pollux from Gemini. --Bowlhover 15:49, 20 April 2006 (UTC)

Because I want to know at what distance the light bulb would have to be to be as bright as an aparant first magnitude star. I guess I could try different distances and approximately determine it, but I'd rather just calculate it. Bubba73 (talk), 17:26, 20 April 2006 (UTC)

In order to represent the brightness of a star in "human" units like lumens instead of "objective" units like watts, you need to know the spectrum of the objects involved. The reason that a 100-watt light bulb doesn't produce "100 watts of light" is that its emissions follow a blackbody spectrum (like most everything) and most of it isn't visible; moreover, it doesn't even quite radiate 100 watts of photons because it conducts some of its energy away through the air. But we can try a couple of very very rough approximations:

1. Just compare the total radiance of the two sources, neglecting conduction for the bulb and the differences in the spectra (which are not necessarily all that great; tungsten light bulbs can be run at up to 3000 K, and the Sun's photosphere is "only" 5800 K — but remember that we could be talking about a blue supergiant star at great distance from us, too).
2. Consider the maximum theoretical luminous efficiency as noted in the light bulb article, and compare that with the known luminous output of the light bulb (850 lumens, from the article).

For either of these we need the luminosity of your first-magnitude star at some distance. Let's suppose (very unphysically; this part is just bookkeeping, not physics) that the star is at the distance of the Sun but still appears first magnitude, so its luminosity (output at all wavelengths) is $100^{(-26.73-1)/5}L_{\bigodot }=3.096\times 10^{15}{\mbox{ W}}$.

1. This is obviously $5.16\times 10^{13}$ times the output of the bulb. The inverse square law says that to get equivalent brightnesses, we need a distance ratio of $7.183\times 10^{6}$, so the bulb should be at $1{\mbox{ AU}}/7.183\times 10^{6}=20.83{\mbox{ km}}$ distance.
2. Alternatively, rate the star (with $95{\mbox{ lm/W}}$) at $2.941\times 10^{17}{\mbox{ lm}}$, which is $3.46\times 10^{14}$ times the output of the bulb, giving $8042{\mbox{ m}}$ as the appropriate distance.

So "across town" (for some size of town) is probably the best we're going to be able to say without considering the luminosity function. Hope this helps. --Tardis 17:59, 20 April 2006 (UTC)

Yes it does. I have just done my calculations by a different route, and I got about 13 miles (20.6 km). Bubba73 (talk), 18:06, 20 April 2006 (UTC)

My calculation: I found on a website that the Sun is 10^24 times as bright as a 400 watt bulb. I took that to be approx 6.7 x 10^24 times as bright as a 60-watt bulb. That is a 62.06 difference in magnitude between the sun and bilb, putting the bulb's absolute magnitude at 66.86. Distance for that to have an aparant magnitude of 1 puts it 6.73 x 10(-13) parsecs away, 12.9 miles. Bubba73 (talk), 18:13, 20 April 2006 (UTC)

Google Calendar-Palm synchronization

The new Google Calendar is absolutely amazing, but of course a glaringly lacking feature is the ability to communicate with or syncrhonize with PDAs. I use my Palm Treo extensively, and despite the advantages of an online calendar like Google's there is no way I can switch to using it if it can't talk with my Palm. I Do you think that Google is working on a way to enable synchronization? Does anyone have any ad hoc solutions? I was thinking about synchronizing my Palm with Outlook instead, then exporting the data to GCal, but I'm not sure how the reverse would work. I think I could use Outlook to pick up the data from Google's Ical web page, but it would be a pain to manually re-synchronize every day and besides, I worry that just copying the entries back and forth would lead to errors, such as multiple copies of an event appearing each time the data are imported. Any ideas or suggestions? — Knowledge Seeker দ 06:57, 20 April 2006 (UTC)

Right now, I don't know of any solutions, but given the way additional utilities like Gmail Drive have been created by third-party users (not to mention the plethora of sites using Google Maps), my tendency would be to wait for a couple of months; I'm sure that Google knows that PDA sync is a big missing feature, and I'm equally sure there's a thousand good hackers who really want to sync Palms with Google calendar. I've had a multiple-copies of events problem with a Palm in the past (in fact, there were a couple of bad syncs, so I wound up with four copies of everything). Personally, I'd be tempted to see if a good solution isn't right around the corner, either from clever open-source hackers or Google itself. I know it's not the answer you're looking for, but I'd rather keep with the old system until June rather than risk screwing up all my schedule data. --ByeByeBaby 23:33, 20 April 2006 (UTC)

Optimal Resolution For Graphics Card

My old graphics card allows 1024 x 800 at 70 Hz, but down at 800 x 600 only 60 Hz. Now I thought that a lower resolution would be easier on the graphics card and allow a higher frequency - do graphics cards find higher resolutions easier to produce? --Username132 (talk) 07:15, 20 April 2006 (UTC)

Generally, a higher res will have a lower refresh rate, but there are exceptions. Maybe someone else can explain the exceptions. StuRat 08:02, 20 April 2006 (UTC)

The refresh rate is the rate the screen is refreshed. in LCD/TFT screens where only changes alter the image it is not very important in Cathode ray tubescreens it does matter since a low refresh rate can be visable to the eye in the form of a "flickering" image. Generally speaking a higher refresh rate is easier for your eyes. Monitors/video cards however have trouble displaying higher resolutions at high refresh rates. It is recommended to use a refresh rate of at least 75Hz on a CRT monitor. The actual digital signal of a Video card is converted to a analog one via the videocards RAMDAC video cards with a old/low quality ramdac might have trouble displaying high resolutions with a high refresh rate (higher datastream)But to sum op your question. No they should not find it easier.. try setting the refresh rate manually ;) --Magicmasta 12:44, 20 April 2006 (UTC)

Basically, 800x600 and lower resolutions are for some reason different than higher ones, and have been like that for a while, though it didn't always used to be that way. 640x480 and 800x600 are often limited to low refresh rates with new video cards/on new monitors and I don't really know why but I've always assumed it was because 800x600 and lower resolutions were no longer "priority resolution ranges" for monitor companies and so they don't bother programming them to perform with optimal settings. Notice that the color range is also limited with low-res settings, thought that may be because of a completely different reason.
There may be a technical reason that high-res monitors/video cards can't handle high-freq/high-color settings with low-resolutions, possibly to do with pixel size, but unfortunately I know little about electronics so I can't give you a straight answer : (.  freshgavinΓΛĿЌ  05:25, 21 April 2006 (UTC)

Quantum Electrodynamics

An electron (1) repels an electron (2) because one of them (1) emits a virtual photon which alters the other's path (2) and thus recoils (1). Why does it "know" when to emit the photon when encounters another electron? Also, is it that the electron created the virtual photon from nowhere? Can anyone also explain why an electron attracts a proton? Is it similar to the previous phenomenon? Thanks! - Just Love Science

It doesn't have to know "when" to trade a virtual photon. The way it actually works is that the probability for the repulsion of the two electrons is given by a sum of all possible ways for the virtual particle to get exchanged. This is an example of quantum weirdness, it's a general phenomenon in quantum theory: you get from the initial state to the final state by summing the amplitudes for all possible paths between. The electron scattering has to sum not only over all the ways to trade a photon, but also the ways to trade two photons, three photons, a photon that splits and recombines in the middle, etc, etc, etc. As for the difference with attractive forces (like between a proton and electron), there really isn't a difference. The minus sign from the charge ends up determining the direction of the momentum transfer, so it goes in the other direction, but it's still a virtual photon exchange. -lethe ^{talk +} 07:44, 20 April 2006 (UTC)

You might enjoy this article from the physics FAQ. -lethe ^{talk +} 07:51, 20 April 2006 (UTC)

Apollo Missions Purifying Agent

Given that the sodium salt of the purifying agent is cheaper and more commonplace why do you think it wasn't used on the Apollo missions?

I assume you mean the carbon-dioxide absorbing filters for the air, which IIRC used lithium hydroxide. I always thought that was to save every gram of weight possible -- 1 mole of sodium hydroxide weighs 40g, 1 mole of lithium hydroxide weighs 23 grams. i.e substituting lithium for sodium gives you the same CO₂ absorbtion capacity for 0.575 the mass. Malcolm Farmer 09:19, 20 April 2006 (UTC)

In addition to the weight issue, sodium hydroxide is extremely hygroscopic—it very readily absorbs water from the air. If you leave a pellet of sodium hydroxide (NaOH) on the lab bench, it will sit there absorbing water until it dissolves into a little puddle of concentrated NaOH solution. Obviously this would present handling problems, particularly in space. While LiOH is also hygroscopic, it is to a much lesser extent. So safety and ease of handling are a couple more reasons to use lithium hydroxide. TenOfAllTrades(talk) 13:26, 20 April 2006 (UTC)

Virtual LBW accurate ?

Well if you watch Cricket matches. You would possibly see a LBW appeal. Then the T.V. Broadcaster or the necessary concerned would show a virtual Field with no Batsman. And the Ball would be in motion to show whether it was really Leg Before Wicket (LBW).But is it 100% accurate ? Will it be able to take completely the wsing, the pitch , the wind etc. --Oasa 10:48, 20 April 2006 (UTC)

I don't think anyone would claim it's 100% accurate. I would imagine that issues like wind shouldn't be important, though, because the trajectory is presumably based on the video of the ball -- any effects like that would be already present in the data used for the extrapolation. But I don't know for sure how they come up with the projection. --Bth 11:02, 20 April 2006 (UTC)

I heard somewhere that, that technology was used to track missiles... so, i guess its pretty accurate...but if a batsman happens to come forward and hit the ball on full toss...the technology might fail in predicting the balls movement after if it had bounced... Jayant,17 Years, India • contribs 15:31, 20 April 2006 (UTC)

The system is called Hawk-Eye, and its accuracy is apparently "measured in milimetres"[1] (that claim comes from the people who make the software for it, so should perhaps be seasoned to taste.) -- AJR | Talk 23:55, 20 April 2006 (UTC)

Eggs

I feel very daft asking this, as I'm sure there is a very simple explanation: When chicken hens lay eggs, are they already fertilised (ie if you keep them in a warm place they will eventually hatch), or are they only fertilised later? If the latter is true, how (as the egg is enclosed in its shell and sealed off from the outside, save for very small pores for breathing)? And what is the biological point of hens laying unfertilised eggs with no rooster around (as I presume is the case in most commercial egg production factories), as they will not get any chicks out of them? — QuantumEleven | (talk) 11:27, 20 April 2006 (UTC)

The eggs are internally fertilized. That's what sex is for. Most aquatic organisms however, do external fertilization, like salmon for instance. English I presume? -- Mac Davis] ⌇☢ ญƛ. 11:54, 20 April 2006 (UTC)

More specifically, the fertilisation happens in the oviduct before the egg is surrounded by the yolk,albumen, shell, etc. As for the "biological point" of laying unfertilised eggs, I'm not sure, but given that the tendency exists it's certainly been bred for over millennia of domestication (and of course in general the trait only has to not be selected against once present -- there doesn't necessarily have to be a positive "point"). (Some info here but none on the "point" of laying unfertilised eggs. Semi-interestingly, searching for this brought up a vast amount of abstruse controversy about vegetarians about whether eggs are veggie-kosher and if so which sort.) --Bth 12:15, 20 April 2006 (UTC)

As a moment of wild speculation, I might guess that the purpose of laying unfertilised eggs is somewhat similar to the purpose of menstruation - to make sure that everything is in prime condition (dare I say it, "fresh") for fertilisation. Confusing Manifestation 12:18, 20 April 2006 (UTC)

Heh, you have edit conflicted me as I was adding that to my answer. --Bth 12:23, 20 April 2006 (UTC)

It is most certainly a trait which was specifically bred for -- there is very little evolutionary advantage that I can see in laying unfertilized eggs (though perhaps if you were expecting predators to steal a few, having "extra" eggs might decrease the likelihood of them getting one of the fertilized ones). In any case, in the case of modern chicken breeds (such as the Leghorn (chicken)), they have been specifically bred to be able to produce high volumes of unfertilized eggs. --Fastfission 15:36, 20 April 2006 (UTC)

Copulation in birds happens before the egg is laid. Without copulation, the egg is infertile. Birds and other animals, including reptiles and fish, can become "egg bound" if they do not pass eggs after ovulation; this may be a reason for the laying of infertile eggs. --Ginkgo100 04:02, 26 April 2006 (UTC)

White spots in nails

I sometimes have white spots in my nails. People say it's due to a lack of calcium, but I'm not sure whether that's true or not. What do you think?

Here's a nice article. [[2]] There are, apparently, zillions of possible causes. --Zeizmic 14:04, 20 April 2006 (UTC)

It is not a sign that you lack calcium. - Cybergoth 01:45, 21 April 2006 (UTC)

about jobs inbioinformatics in india

Sir , I want to know that can an computer engineer can enter in bioinformatics field.If so then how . Please guide me .

Sure. If you look at the bioinformatics article, you'll see all the other field that relate to it. Having some knowledge of statistics, DNA, protein folding and evolution will probably put you at an advantage. I know, though, that the Bioinformatics Master's course at my old university, Edinburgh University, really only expected knowledge of coputer science. I'd recommend looking at the department websites for universities in your area. — Asbestos | Talk (RFC) 15:38, 20 April 2006 (UTC)

Calculating the curve when one wheel is faster than the other

I'm writing a little program modelling a simple robot. The robot has two wheels, one on either side. It turns by making one wheel faster than the other. I'm just taking into account absolute speed — acceleration is instantaneous. If the left wheel is at speed x, and the right wheel at speed y, how do I calculate the robot's position and orientation at time t + 1?

Any advice would be really helpful! --Mary

Depends upon how far apart the wheels are.

Ok, set any distance: one unit. --Mary

Assume y>x without loss of generalization. Hence the robot translates along a straight line (in the direction of x in the last time step) with speed x. Also the wheel with speed y will try to rotate with an angular velocity (y-x)/d. Where d is the distance between the wheels. You can superpose these motions together to find the position at the next time step. Hope that helps. --coolmallu 16:45, 20 April 2006 (UTC)

Well, I worked it out using the info at http://rossum.sourceforge.net/papers/DiffSteer/. Rather complicated, but I think I got it. Thanks, --Mary

I didn't understand your comment that "acceleration is instantaneous". That's impossible, an infinite accel would require an infinite force or zero mass using F = ma. StuRat 17:30, 20 April 2006 (UTC)

Not it is not, all you do start the time when the robot is moving at top speed, then the accelleration is zero.

I think she means to use the simple approximation that the robot starts at rest at position 0, but then instantly starts off with the wheels going at speeds x and y, so you don't have to worry about the effects of gradual speeding-up. You could just consider starting with the robot already moving. Confusing Manifestation 18:15, 20 April 2006 (UTC)

She never said she was actually building the robot. It's just a computer model.  freshgavinΓΛĿЌ  05:12, 21 April 2006 (UTC)

Here's an answer - I think it's right, assuming there is no side-slipping allowed with these wheels: If x and y are constant, the robot must travel in a circle (a picture would be very useful here, but oh well). The inner wheel will trace out a circle of radius $r$, and the outer wheel will trace out a circle of radius $r+d$. Thus, in one full rotation of the robot, the inner wheel will have travelled $2*\pi r$ and the inner wheel will have travelled $2\pi (r+d)$. Dividing by the respective velocities yields the time taken for a complete rotation. From the nature of the motion, the times for the two wheels are equal, so $t=2\pi r/x=2\pi (r+d)/y$. Simplifying and solving for r, $r=d(x/(y-x))$. This is the radius of the robots path for a given d, x, and y. Hope that helped!

--Bmk 23:36, 24 April 2006 (UTC)bmk

bromine

how the bromine produced industrially?

Bromine is a chemical element, so it might be more appropriate to ask how it's extracted than how it's produced. Bromine#occurrence does have some details about the extraction methods. StuRat 17:15, 20 April 2006 (UTC)

The question was probably about the substance Br₂, which is produced from brine by electrolysis. —Keenan Pepper 17:26, 20 April 2006 (UTC)

Ironic since you can produce brine from bromine by extracting the "om". Grutness...wha? 02:42, 21 April 2006 (UTC) (OK, I'll shut up now)

I was just going to say RTFL Bromine, but gosh-golly it doesn't say. I got this from a USGS report:

Based upon USGS estimates of quantities produced during 2000, Arkansas continued to be the leading bromine-producing State, accounting for most U.S. production. Michigan was the only other State that produced bromine. Mining operations in both States extracted subsurface, bromine-rich natural brines by submersible pump for subsequent processing. --Zeizmic 17:17, 20 April 2006 (UTC)

Keratin

What is the chemical formual for keratin? Like, water is H2O, and the hydrogens connect to the oxygen at the 100 degree angle. 64.198.112.210 15:57, 20 April 2006 (UTC)

First off, Keratin isn't a molecule in the same sense that water is, it's a protein. Proteins are chains (sometimes balls of tangeld-up chains) of amino acids linked together. I can give you some clues on which elements it contains, though:

All amino acids contain Carbon, Hydrogen, Oxygen and Nitrogen, furthermore, keratin is a textbook example of a protein rich in Sulfur, 24% of it being made up from Cysteine, a Sulfur-containing amino acid. -Obli (Talk)^? 16:10, 20 April 2006 (UTC)

I mean chemical structure, sorry. And more like the pictures that you draw to show how molecules built, like the third part of the first picture in molecule. 64.198.112.210 16:01, 20 April 2006 (UTC)

As stated in my previous answer (which was answering the wrong question), Keratin is made up from numerous amino acids, the sequence of them detemining how they will attract each other and how the chain will bend. I found this picture of how amino acids interact, it's not the structure of keratin, but it shows the general makeup of a protein. -Obli (Talk)^? 16:23, 20 April 2006 (UTC)

Proteins have four levels of structure: primary, secondary, tertiary, and quarternary. For this reason, models of proteins tend to be very complex. Is there a specific reason you need the crystal structure of keratin? Perhaps the information might be found in other ways. Isopropyl 00:31, 21 April 2006 (UTC)

Three-dimensional structures of proteins (determined mostly by x-ray crystallography, sometimes by NMR methods) are deposited in the Protein Data Bank. That article also tells where one can find viewers. (I like pymol). Unfortunately, when one throws the keyword "keratin" at the database, no hits come up. If you are interested only in the amino acid sequence you will want to look at the Swiss-Prot sequence database. Dr Zak 02:33, 21 April 2006 (UTC)

Intermittent hormone therapy

I am trying to find information on: intermittent hormone therapy treatment for Prostate Cancer.

Thank you. -------

Are you talking about testosterone blockers ? StuRat 17:09, 20 April 2006 (UTC)

I always thought nowadays uses compounds that decrease the level of testosterone in the body. GnRH is the first hormone in the regulatory chain, then come FSH and LH, which in turn act on the level of steroid hormones. GNRH1 analog is another good keyword. And look out for the name of Ralph Hirschmann at the University of Pennsylvania. He had a hand in the research during his tenure at Merck. Dr Zak 22:50, 20 April 2006 (UTC)

According to Dr. Peter Scardino, who is the chairman of urology at New York's Sloan-Kettering Cancer Center, intermittent hormone therapy is intended to balance the benefits of hormonal control along with a reduction in unpleasant side-effects. As the name implies, it involves periods of hormone therapy alternating with periods where the drugs are interrupted. The hormones are resumed when levels of prostate-specific antigen (PSA) begin to rise.

Doctor Scardino seems less than impressed with this method, since the side effects of hormone therapy only begin to abate by the time the drugs must be resumed. Since the drug-free periods tend to shorten over time, the implication is also that interruption allows the cancer to progress more rapidly or even develop resistance to hormones more rapidly. Here's a link to his book: Dr. Peter Scardino's Prostate Book--Mark Bornfeld DDS 16:01, 21 April 2006 (UTC)

Really dumb java question

I can't seem to import correctly in my Main method. My main method is in package a. I have a number of classes in package a.b, including MyObject. When I say

package a;

import a.b.*;


public class Main {

    public static void main(String[] args) {
           
        MyObject o = new MyObject();      
    }
    
}

it says "Cannot find symbol: constructor MyObject() in location a.MyObject.
If I change the import line to

import a.b.MyObject;

it works fine. Note also that importing, say, Java.util.* works fine. I'm using the NeBeans IDE.

I know this is dumb, but I can't work out what's wrong. Any help? --Mary

Sounds like you have a name conflict between packages a and a.b. Perhaps there is a MyObject in each? Or else you moved classes around and have stale .class files. It also sounds like you changed the names for the question; I'd try making a new, clean test with just two classes in new packages, and then gradually make them look more like what you want the real code to be until the problem occurs (at which point the cause should be clearer). (Also, note that computer science questions are now supposed to go on the math desk.) --Tardis 18:12, 20 April 2006 (UTC)

I guess that was it. There were no other .java or .class files in the folder that I could see, but when I performed a 'Clean and Build' in NetBeans it worked. I guess I don't really understand where NetBeans is keeping its class files, but that seemed to solve it. Thanks! --Mary

Backing up DVDs

This may or may not be appropriate for this reference desk, but can anyone recommend a piece of widely available, layman-accessible software that I could use to make a few copies of my DVDs (I'm leaving for college and don't want to risk losing my entire collection). I haven't got any nefarious designs, but I expect it's probably illegal anyway. Any suggestions? Bhumiya (said/done) 17:34, 20 April 2006 (UTC)

Not a lawyer, of course, but as I understand US law (US from your user page), there's nothing illegal about simply copying a DVD for personal use; see fair use. If you decrypt the DVD's contents, you can run afoul of the DMCA, but that's not inherent to copying. The DMCA might also have something to say if you have to "circumvent" (whatever that means) other copy-protection on the disc. I believe that standard DVD burners like, say, Toast for OS X are capable of doing what you want, but I don't have a list of those handy... maybe optical disc authoring software and its links would help? --Tardis 18:30, 20 April 2006 (UTC)

You may want to check out the comprehensive guides on DVD-Backup from Doom9, accessible here. All the software you need can be found in the "downloads" section of the site. --Aramգուտանգ 19:09, 20 April 2006 (UTC)

The problem you will run into is that most commercial DVDs are dual-layer, and so hold more information than the single-layer DVDs that you probably have the equipment to burn. There are ways around this, but they're not perfect and not very simple. Henry^Flower 21:45, 20 April 2006 (UTC)

Impurities

What are the effects of impurities (like Arsenic,Antimoney,Bismuth) Copper. Please explain in detail?

What are the circumstances? Are you asking how these impurities are found in copper or how you would remove those impurities or what are the properties of impure copper metal, etc? --Chris 19:24, 20 April 2006 (UTC)

A/D converters

What are the characteristics of A/D converters in data acuisition?

THANK You

If you type "A/D converter" into the search box up there $\uparrow$, you will be taken to our article about Analog-to-digital converters, which tells you a lot about them. -- AJR | Talk 00:28, 21 April 2006 (UTC)

Allergy

I bought a Hot Tub last year for use in our Scottish Garden. The Tub was made in California by a reputable manufacturer and distributed in Scotland by a highly responsible specialist dealer. My wife and family, as well as several friends, use it regularly and enjoy it immensely. But me? Every time I use it I break out within hours with an incredibly itchy skin, mainly on my back but also on my arms and legs. I have consulted both the manufacturer and distributor and have had great support from them in trying alternatives to the stabilised chlorine granules they normally recommend. These alternatives have included non-chlorine monopersulfate granules. But alas, to no beneficial effect. I religiously clean the filter and monitor the PH, Alkalinity, and Water Hardness and dose them accordingly, and I always shower thoroughly after each Hot Tub. But of all my family and friends, I seem the only one affected. My question is this; Is there a way of treating the water so that I can enjoy the use of the Tub without the adverse side effects described above, or am I consigned for all time coming to be on the outside looking in? The others are quite happy with that latter situation as I make a very good Gin and Tonic for them to enjoy whilst bathing. My Hot Tub suppliers claim not to know of any other similar sufferers in Scotland. Sorry for the length of this whine but thanks in anticipation for any advice.195.93.21.42 18:46, 20 April 2006 (UTC)

Would you like some cheese with that whine? Hehehe. Could you be more specific as to what chemicals you are using to treat the water? There is obviously more than just chlorine that you could be reacting to. It may even be something as crazy as what material the hot tub is made out of. You may also want to consider seeking the advice of a physician, perhaps a dermatologist or allergy specialist. --Chris 19:20, 20 April 2006 (UTC)

I would think that bromide and ozonation would be two alternatives --WhiteDragon 19:41, 20 April 2006 (UTC)

Indeed, I use bromine tablets in my hot tub. Switching over from chlorine to bromine probably would require draining and refilling the tub, however. I believe that with ozonators, it is still necessary to use a sanitizing chemical, albeit in smaller quantities. --LarryMac 19:50, 20 April 2006 (UTC)

You could pay big bucks and convert to a saline spa. These are very mild with almost no irritation. We don't have an article on it, but basically the water is salted to 1/6 of seawater, and an electrolyser produces pure sodium hypochlorite. I've seen them, and they don't produce the halide by-products that are so nasty. --Zeizmic 20:19, 20 April 2006 (UTC)

My opinion is that if the manufacturers do not have any helpful suggestions you are probably out of luck. Talk to your Physician. Maybe you are hypersentitive to something else?

It does seem like an allergic reaction, and it could be quite beneficial to find out what exactly it is. Contacting your physician for an allergy test would be a wise course. If whatever is causing it is in one product, chances are good it's out there in other forms as well. (Basicly they test you for a large number of allergens, i believe by exposing your skin to tiny amounts, see if you have any uncommon response) SanderJK 22:41, 20 April 2006 (UTC)

Are you sensitive to the water temperature (ie. is the water too hot for you)? - Cybergoth 01:52, 21 April 2006 (UTC)

I suggest you dump the old water, carefully rinse the hot tub out, then refill it, but don't add chemicals. Then try it and see if you get the same reaction. This will tell you if it was something in the water causing the problem or perhaps just a reaction to hot water. I've often thought that a distillation process would allow the water to be cleaned without any nasty chemicals. This method would require an exterior tank to keep the distilled water separate from the dirty water, and would require lots of heat, but that wouldn't be so bad if you needed to heat the water anyway. Perhaps a timer could be set to run the distillation process right before you plan to use it. Time to file my patent ! StuRat 07:03, 21 April 2006 (UTC)

I think your skin is reacting to whatever the tub is made of or coated with. As a test, sit in a regular bathtub with the same temperature and add the same chemicals, but don't transfer water from the california hottub. Maybe some sort of coating on your hottub would help. Or a liner? WAS 4.250 10:12, 21 April 2006 (UTC)

Planet Orbits

On diagrams and pictures, all the planets seem to orbit on one level plane (with the exception of Pluto). Is this correct? Why do all the planets roughly orbit the sun on the same plane? I thought the effects of gravity worked on all planes.

Mainly because the accretion disk theory says that the planets form from a flattish blob of matter, rather than a spherical one. Pluto tends to be the odd one out in these things, which is why its status as a proper planet tends to be in dispute. Confusing Manifestation 20:02, 20 April 2006 (UTC)

As an aside, Pluto has lots of other problems too. It's not a gas giant despite the fact that it's on the outer part of the solar system, and it's actually part of the Kuiper Belt, which has many large objects, at least one of which is probably larger than Pluto. There's plenty of more information on those pages and several more I'm sure. EWS23 | (Leave me a message!) 20:13, 20 April 2006 (UTC)

Also take into account the theory of gravity - the planets will pull each other closer. They may have started on a tilted plane, but when they near each other in orbit, they will pull the plane of their orbits closer. Also, there is the spin of the sun. It is most likely not a coincidence that the planets orbit in the same plane that the sun spins. --Kainaw ^(talk) 20:52, 20 April 2006 (UTC)

And the planets all orbit in the same direction the Sun spins (except Pluto) right?

Yes, all planets in our solar system (including Pluto, actually) orbit in the same direction. Most of the planets also rotate in the same direction, but Venus, Uranus, and Pluto all exhibit retrograde rotation. Prograde and retrograde motion is a good read. EWS23 | (Leave me a message!) 00:39, 21 April 2006 (UTC)

If memory serves, Uranus is a weird one in that the direction of rotation is a bit of a guess. The best description of it is that it rolls around the orbit. The axis of rotation point directly toward the sun (or directly away from it - depending on your point of view). Since neither axis points "north", it is not easy to say which way it is rotating. --Kainaw ^(talk) 01:10, 21 April 2006 (UTC)

Well remembered. The page that I linked above says:

Uranus rotates nearly on its side relative to its orbit. It has been described as having an axial tilt of 82° and a negative rotation of −17 hours, or, equivalently, of having an axis tilted at 98° and a positive rotation. Since current speculation is that Uranus started off with a typical prograde orientation and was knocked on its side by a large impact early in its history, it is most commonly described as having the higher axial tilt and positive rotation.

EWS23 | (Leave me a message!) 03:30, 21 April 2006 (UTC)

A couple of other pages of relevance: ecliptic plane and invariable plane. --Bth 23:12, 20 April 2006 (UTC)

Ocean Trenches

I can't find how they are formed. How are they formed? I am in grade school so i don't know how all of this wikipedia works.

Read Oceanic trench and subduction. They might be a little heavy going for you, but try them and then ask again back here if there are things you don't understand.-gadfium 22:53, 20 April 2006 (UTC)

They form when one piece of the Earth ends up going under another through subduction, then there's a crack. -- Mac Davis] ⌇☢ ญƛ. 04:20, 21 April 2006 (UTC)

The hardest part is geting the scale of things to make sense in your mind. The continents (land) and oceans are just a thin film on a very hot slow rolling "boil" that over billions of years causes the thin surface light-in-weight rock to move like some thin film on the surface of water being boiled in a pot. The relative thinness of the surface of the Earth and the vast stretches of time involved in shaping it are hard to come to grips with for many people. WAS 4.250 09:55, 21 April 2006 (UTC)

We need a Wikly-pedia for late grade school to early highschool. I find that many of the science articles are somewhat ridiculously post-graduate. --Zeizmic 13:06, 21 April 2006 (UTC)

Hardly, most are barely under-graduate--152.163.100.74 20:50, 22 April 2006 (UTC)

Yeah...for anything above that, click the links at the bottom of the "heavier" articles :)

April 21

where do baby internet trolls come from?

surely the adult form doesn't find any time to reproduce, so where do the little ones come from?5r75r 00:10, 21 April 2006 (UTC)

The stork leaves them under cots -- AJR | Talk 00:38, 21 April 2006 (UTC)

Trolls are like prions; they twist innocents into their own shape.-gadfium 00:57, 21 April 2006 (UTC)

Funny thing - I was accused of being a troll just a couple days ago because I said Americans can be just as stupid as African "savages". Then, later, I said the United States can be (and has been) just as imperialistic as China. Since I disagree with the accepted notions that Africans are inferior to Americans (especially the white ones) and China's government is pure evil, I suddenly became a newborn troll. Now, I don't know what to do. Should I continue thinking for myself and becoming more and more of a troll - or should I dump my brain in the garbage and start making more palatable posts? --Kainaw ^(talk) 01:18, 21 April 2006 (UTC)

I was the one refuting your absurd accusations that Hawaii is under a military occupation equivalent to that of Tibet by China. However, I never called you a troll, although I do question whether you should be permitted out at night by yourself, LOL. StuRat 06:49, 21 April 2006 (UTC)

I did not intend to imply that you called me a troll. You are a well-respected Reference Desk user. It was an anonymous-coward who called me a troll. Because I feel that nobody else is interested, I will attempt to explain my theory of the Hawaii-Tibet relation on your talk page. Cool? --Kainaw ^(talk) 12:15, 21 April 2006 (UTC)

Must be a spontaneous mutation. - Cybergoth 01:54, 21 April 2006 (UTC)

Or just a dormant trait.  freshgavinΓΛĿЌ  05:04, 21 April 2006 (UTC)

I don't think there's anything wrong with saying that Americans can be just as stupid as Africans. Jonathan ^talk File:Canada flag 300.png 18:05, 26 April 2006 (UTC)

Everyone knows that internet trolls come from under internet bridges. M@$+@ Ju ~ ♠ 22:30, 21 April 2006 (UTC)

Are you sure the Chinese government is pure evil? It doesn't leave many categories to describe the many goverments featured in List of war crimes does it? Have you tried gas chromatography or mass spectrometry to confirm the degree of purity of the evilness? FT2 (Talk) 19:07, 26 April 2006 (UTC)

help me get into a med school!

I know a lot of the scholarly types visit this place so i was wondering, i want to get into medical school so i can grow up to be rich and famous. the question is, what do you think is the best way top get into a med school? im not very smart. easily confused. and not very motivated. although im sporting a 2.9 gpa in my 5th year as an undergrad so not too shabby. im one of those not very motiveated ppl who neevr fit the cookie cutter nerd mold. and i dont like scinece or biology or math very much. but im a real social out going guy who loves to party and lives off his parents considerable finances so i should have no trouble overcoming my shortcomings. plus i have a convertable bmw and im only 26 years old. not to mention i love to network and have lots of people skillz. could do mad well in the business world but i want to help people. question is. how would my parents money best be spent in helping me get into medical school on my own merit? i dont like tutors mind you their some boring no life book nerd who never get good results anyway. and i do poor on placemnts. question, help me get into med school. also i hate lecturs and lavs bunch of bullshit book learning never got anyone street smarts in medical school--Iwantasportscar 00:18, 21 April 2006 (UTC)

Consider not going to med school unless you can make yourself study for the MCAT. Isopropyl 00:24, 21 April 2006 (UTC)

you think i could hire someone else to take the test for me. i mean the mcat ppl dont really know what i look like anyway how are they going to know who really took the test or not--Iwantasportscar 00:31, 21 April 2006 (UTC)

I agree. No offence, but if you just want to be "rich and famous", try to find a profession in which people don't die if you screw up. If you "dont like scinece or biology or math very much", you probably won't enjoy a medical job anyway. —Keenan Pepper 00:30, 21 April 2006 (UTC)

Also, if you fail your MCAT, you likely will be sued for malpractice multiple times. So, you will never get rich, but you may get famous for your ineptitude. You should consider advice a Norwegian woman told me when I was in Tromsø: Being successful in America is easy. Just go to medical school and be a doctor. If you are too stupid to be a doctor, go to law school and be a lawyer. If you are too stupid to be a lawyer, just be a politician. --Kainaw ^(talk) 01:24, 21 April 2006 (UTC)

I think Iwantasportscar really wants to be a writer, and this question is a little exercise. (See also the previous question.) Clearly you have enough talent to get published on USENET --GangofOne 01:42, 21 April 2006 (UTC)

You could always sell your BMW and buy a hot-dog mobile. You'd be relatively rich (fifty grand in your pocket) and somebody would probably take a picture of you and put you in the paper for being a moron and driving in a hot-dog mobile, thus making you sub-famous for a few days.  freshgavinΓΛĿЌ  05:02, 21 April 2006 (UTC)

I apologize but are you serious about this question? If you are as you describe, going to Med school will NOT make you rich and famous. It doesn’t sound like you really have the passion, desire or discipline required for Med School. You have to love what you do and do it well.

Maybe you could ask a real doctor? "Wow you are the dumbest fucking idiot ever. Instead of your stupid ws.arin.net why don't you try ip2location.com. As for the location in Virginia--that is WHERE VERIZON is headquartered! Put the IP that I used at work into ip2location.com and it comes up LOS ANGELES. You dumb fuck. Speaking of idiots...you are using AOL. And what is your obsession with me? Are you so jealous? Did you aspire to be a doctor but failed? I look forward to you agreeing with me that you are the dumbest fucking idiot ever. I had to say that twice because maybe it didn't get through your thick skull. More about me: I make about 270K per year, and live in a million dollar home. All at the age of 31! :) User:ER MD 10:46, 31 March 2006" (UTC)[3] --GangofOne 19:49, 21 April 2006 (UTC)

Hey, I think I knew you in college! Ginkgo100 03:56, 25 April 2006 (UTC)

An old adage says that the most reliable two ways to become a millionaire are to marry a millionaire – or divorce one. Since female millionaires are less common than male millionaires, and you clearly want the laziest way, may I suggest emigrating to Canada, Holland or South Africa, all of which countries have a Western style culture and permit gay marriage, and therefore will give you the best percentage odds of success in your quest. FT2 (Talk) 19:02, 26 April 2006 (UTC)

Schizoaffective disorder

Do shizoaffectives have cycles of mania and depression like bipolar people do?

There are apparently two types, "bipolar schizoaffective disorder" and "depressive". Why don't you take a look at the schizoaffective disorder article? - Cybergoth 02:48, 21 April 2006 (UTC)

Old people

Why do old (70+) women develop facial hair? I know they've always had facial hair, but some old ladies are about as hairy as pubscent boys. A Clown in the Dark 01:14, 21 April 2006 (UTC)

Lack of estrogen after menopause. Men with estrogen treatment stop growing as much facial hair. --Kainaw ^(talk) 01:20, 21 April 2006 (UTC)

I believe the ratio of testosterone to estrogen controls facial hair growth, among other things. StuRat 06:40, 21 April 2006 (UTC)

Anatomy

Acidosis occurs when arterial blood pH drops below what?

7.35. I recommend you read Acidosis. A Clown in the Dark 01:49, 21 April 2006 (UTC)

Actually, you've got causality a bit mixed up there. Acidemia is when plasma pH is less than 7.35. Acidosis is the underlying disorder that caused the acidemia. --David Iberri (talk) 03:04, 21 April 2006 (UTC)

Anatomy

The predominant extracellular cation is the what?

What is Sodium? - Cybergoth 01:58, 21 April 2006 (UTC) ("I'll take Anatomy for 400, Alex")

Correct goth, Potassium would also be accepted. :P -- Mac Davis] ⌇☢ ญƛ. 04:24, 21 April 2006 (UTC)

I certainly hope Alex would know enough to respond, "No, sorry" to potassium. THe predominant extracellular cation is sodium. The predominant intracellular cation is potassium. That's the whole point of the question! - Nunh-huh 04:32, 21 April 2006 (UTC)

Orca distribution

According to Wikipedia "The orca is the second-most widely distributed mammal in the world, after the human." but surely rats must be a candidate for this title? Thank you

This is due to it huge area that the orca has. The ocean is a big place. Some kind of insect would probably come after, or other kinds of whales. -- Mac Davis] ⌇☢ ญƛ. 04:28, 21 April 2006 (UTC)

Insects aren't mammals.-gadfium 06:39, 21 April 2006 (UTC)

But they are animals. Oh, on the page it says animal. -- Mac Davis] ⌇☢ ญƛ. 11:28, 21 April 2006 (UTC)

Aeration treatment

I want to know about the "aeration treatment" which is extensively used in water treatment systems. If anyone can answer to the following question regarding the aeration systems,it will be a great help for anyone who searching information about that.

1. How does the aeration affect in treating sewage or waste water?

(What will happen to the waste water in the aeration process?)

1. Specifications of the aerators used in various occations?
2. How does it reduce the BOD & COD level of waste waters?

IF anyone can publish an article about this, It would be great..!!! (Sithara from Sri Lanka)

Basically, it gives the microorganisms in the water all the oxygen that they use up while breaking down (oxidising) the wastes. Biological Oxygen Demand is a measure of how much oxygen is used up by organisms as they try to consume the waste, the end result of aeration should be reduction of the BOD as the wastes have been removed. Sewage treatment should answer your questions. Malcolm Farmer 19:27, 21 April 2006 (UTC)

Basic mechanical reference.

Doubtless, you are aware of how mindbogling an array there is of guages, types and other descriptions of basic items like screws and threads and wires sizes and so on. Is there any central location (web or print) that has all of it in an easily cross-referenced format? I plan to make excel files eventually, unless someone has them. Thanks! Feel free to respond directly. (email excluded)

Dunno if there's a counterpart on the web, but as far as print goes, you can buy a copy of the current edition of "Machinery's Handbook". Erik Oberg, Franklin D. Jones, Holbrook L. Horton, and Henry H Ryffel are the authors, the publisher is Industrial Press, Inc., New York. It's 2,640 pages, and the ISBN is (at least for the 26th Edition) 0-8311-2625-6.

A much cheaper version is the "Pocket Reference" booklet written by Thomas J. Glover, and published by Sequoia Publishing, Littleton, CO. ISBN 1-885071-00-0 —The preceding unsigned comment was added by 216.163.128.130 (talk • contribs) 13:50, 21 April 2006.

I have no idea if you care, but there's a biological equivalent: Registry of Standard Biological Parts. Isopropyl 04:53, 21 April 2006 (UTC)

Body decomposition rate

How long does a body in a fancy tomb take to decompose, versus a body buried simply in a casket in the earth? And does the casket affect the rate? Thank you. PatrickJ83 05:12, 21 April 2006 (UTC)

I don't know about the rate, but the casket and surrounding concrete vault will most definitely slow decomposition by keeping water and organisms out. Embalming also greatly retards the decomp rate. StuRat 06:34, 21 April 2006 (UTC)

The decomposition rate is determined by things other than how "fancy" the tomb is: temperature, humidity, acidity, being eaten or not by whatever from bacteria to dogs, method of body preparation. Burial of executed criminals in no casket at all in north european peat bogs was extemely preservative of the bodies. WAS 4.250 09:32, 21 April 2006 (UTC)

Thank you, but do u think it takes, say, 50 years for the soft tissue to decompose in a 'fancy' tomb above ground and maybe 10 years in a coffin in the Earth? This is under normal circumstances, no preserative beat bogs or anything. Without embalming. Thanks PatrickJ83 17:43, 21 April 2006 (UTC)

It depends. Louisiana or Montana or Nevada? Humdity and temperature matter. How safe from flys and worms. Buried in clay could be safe from worms, above ground could be fly food. How decomposed is "decomposed"? I recommend you take a piece of meat and put it somewhere and look at every day or so. Maybe even write down your observations. Maybe even have a few pieces of meat; one outside, one in the dark, one in the light... WAS 4.250 18:14, 21 April 2006 (UTC)

Would a piece of meat really be a good experiment to contrast with a human body? I would have to bury the piece in a coffin in the ground and then bury another piece of meat in a marble tomb, HA! Anyway I digress. The reason I asked this question in the first place is because I was reading in a magazine about a newish trend of people buying above-ground tombs for themselves instead of being buried in the ground as they think it's more noble. But does this slow down decomposition rate? Would a body buried in a marble tomb in a church take, say, 100 years to decompose to skeletal remains? That's really what my question boils down to. Thanks you guys! PatrickJ83 21:34, 21 April 2006 (UTC)

A better subject for your experiment would be a whole animal carcass, rather than just a piece of meat. Ginkgo100 04:00, 25 April 2006 (UTC)

I've seen news reports on coffins for sale in Japan that have dehumidifiers, interior lighting, and even air conditioning, so be careful when referring to "fancy" coffins.  freshgavinΓΛĿЌ  05:58, 26 April 2006 (UTC)

A text book on forensic autopsy might help, the decomposition of the human cadaver under a wide range of circumstances is a very well studied subject..... sadly most of all in the context of establishing the circumstances of death of a body. FT2 (Talk) 18:57, 26 April 2006 (UTC)

Why does some chewing gum disintegrate in your mouth?

Example: Altoids Sour Apple Chewing Gun disintegrates in your mouth after chewing it for 5 - 15 mins.

Description of phenomenon: The Gum looses all flavor and it begins to get really soft as you chew it...the texture and the elasticity is gone. It them becomes like a glob of paste and disintegrate in your mouth.

Possible answer found on on HighBeam Research but did not have full access to read the article (Chemistry and Industry, May 2, 2005): "Chewing gum can be a disappointing experience of short-lived flavour or grainy texture, largely due to the method of manufacture. There are two basic processes: the first is to mechanically mix gum base compounds/polymers. This tends to produce a nice texture, but can destroy encapsulated flavours, The second method is to compress discrete gum base particles, a process that is gentler on the additives but can result in gum that disintegrates too easily on chewing."

Question: Can some elaborate or confirm if the explanation is true?

I like that stuff! I think its because there are almost no purposeful elasticity agents in the gum. Its not really gum, its just sugary soury stuff that is like a chewy sweet tart. Most gums have stuff like chicle or plastic-like substances to make them elastic, for the pleasing feeling for the chewer. Sort of how people love chocolate for one reason that it melts just under your mouth's temperature. Mmmmm. -- Mac Davis] ⌇☢ ญƛ. 11:33, 21 April 2006 (UTC)

Not exactly your question, but certainly related: http://www.straightdope.com/classics/a2_201.html —Keenan Pepper 14:53, 21 April 2006 (UTC)

Fantastic. Now we can work on that other important question, "Does your chewing gum lose its flavor (on the bed-post overnight)?" Confusing Manifestation 12:34, 22 April 2006 (UTC)

Speed of Heat through Space

My question is .." Does heat travel through space at the same speed as Light (close to 300,000 Kilometers per second)?" if it does can I have a reason Thanks Tony Stevenson

Someone else will no doubt have better information on this than me, but ISTR that both heat and light are radiant energy by-products of electromagnetic radiation and therefore travel through vacuum at the same rate. Grutness...wha? 09:17, 21 April 2006 (UTC)

Heat in the form of thermal radiation and all light is EM radiation, not a byproduct. But note that heat can take many different forms, not all of which are radiative. Light on the other hand is, well, light, and is always radiative. However, in a vacuum the only transfer of heat is via photons, so yes, through space heat and light are identical in almost every respect (aside from visibility to humans and a reasonable difference in energy per photon). --Tardis 18:23, 21 April 2006 (UTC)

Thanks for the answer, I still don't understand why the heat from the sun in the morning takes a while to heat the earth.. if an atomic bomb was to be let off in space would a spaceman say 600,000 kilometers away be burnt to a cinder in 2 seconds? surely he would see the light before being burnt?

The time taken to heat up in the morning is nothing to do with the speed of the heat. After all, the heat already left the sun, and has arrived by dawn. The time taken is because there is only so much heat available, and because there is an awful lot to heat up. Notinasnaid 10:15, 21 April 2006 (UTC)

Assuming the spaceman is not hindered by anatomical difficulties that regulates the speed of which he observes, but instead acts like a neutral, single-photon sensitive sensor, an answer can be given that hopefully isn't very bad. The explosion takes place, and photons will be emitted spherically. Now, after two seconds, ONE photon is destined to arrive at the spaceman before the others, or along with a couple of others. He will detect this photon. Within very little time, other photons will also arrive. Remember that photons will one by one clash into the spaceman, and heat him up until being burnt dead (assuming that is the effect of a nuclear bomb at 600,000 km). The answer to the question is then that yes, he will detect light before being burnt. However, another answer, equally true, says that AS HE DETECTS the first photon, a part of him, even if only an electron or something, will be affected ("burnt"). If you like, he is burnt, but on a very, very small level, because as soon as a photon hits him, energy is transferred, and heat is created on a very, very tiny level. The difference between this and actually having the hole man burn up, is just a matter of how many photons are needed to clash into all of him. Likewise, your earth is heated up as soon as a photon hits, but the more photons arrive over a longer duration, the more heat it gets. 213.161.190.228 10:34, 21 April 2006 (UTC) Henning

Just to give a sense of scale, any normal nuke at that range will have little to no effect; that distance is nearly one hundred Earth radii. A human (taken to have a ridiculously large presented surface area of 2 square meters) will intercept approximately 4 mJ of radiation of various kinds from a multi-megaton explosion at a range of $6\times 10^{8}{\mbox{ m}}$. This energy, if evenly distributed, will raise the person's temperature by some 15 nK -- entirely insignificant. There might still be some concerns from, say, gamma irradiation damage, especially since there's very little material present to convert the initial reaction radiation into lower-energy forms (like molecular motion or thermal photons), but I suspect that a man on the Moon would be quite safe from all effects of nuclear explosion taking place very nearly on the opposite side of the Moon's orbit (but in line-of-sight; not talking about Earth as a shield here). --Tardis 18:23, 21 April 2006 (UTC)

It is a good answer but not the one I wanted to read... so I lose the bet.. Thanks again Tony

Heat can be transmitted in two ways: One is convection/conduction, where the heat is transmitted in the form of the motion of atoms and molecules. In that case the theoretically fastest speed it could move at would be the speed of sound in that medium, although it's usually much slower. The second way (and the way the heat of the sun gets here) is through infrared radiation (which, when absorbed by molecules turns into kinetic energy), in that case the heat moves at the speed of light. As for why it takes a while to heat up the earth, that's the same answer as for why it takes a while to heat up a pot on a stove. Note that in the morning/evening, the light is coming in at an angle, and there's less incident light, and more of it is getting absorbed by the atmosphere and not making it down to ground-level. Which is also why we have seasons and why it's colder near the poles. --BluePlatypus 12:14, 21 April 2006 (UTC)

We're dealing with separate phenomena here. The reason that it takes a while for the Earth to warm up is because of its specific heat. The way that heat is transferred to the Earth by the Sun is not by direct conduction (as there is very little matter in between) but by electromagnetic radiation. The amount of energy delivered is inversely proportional to the wavelength of the light. Tying this to the atomic bomb thing, the reason you don't die when you're so far away from the bomb is because intensity decreases with the square of the radius; doubling the distance cuts the intensity to a quarter. Also, bombs propogate shock waves as fast as possible through their surrounding media, approximately the speed of sound. Isopropyl 13:58, 21 April 2006 (UTC)

...But note in case of confusion that shock waves exist only when dealing with matter: A bomb in space would produce no shock wave. — Asbestos | Talk (RFC) 20:19, 21 April 2006 (UTC)

In a pure vacuum, heat would radiate at the speed of light, and there would be no convection or conduction of heat. Space, however, isn't quite a pure vacuum, so, while most heat would radiate at the speed of light (as infrared radiation), some would be absorbed by matter in space, and later radiated back. So, there would be some lagging heat which could arrive considerable later. I'm not sure if the amount of lagging heat would be significant or not. StuRat 22:08, 21 April 2006 (UTC)

palaeanthropus palestiensis

My Harpers Bible Dictionary refers to eight giant human skeletons from around 100,000 years ago being found in a cave on Mt Carmel and calls them Palaeanthropus Palestinensis. I am unable to find any further info on them, could someone direct me onwards. Thamks Hatch

Never heard of it before, but some research suggests that "Palaeanthropus" is considered a simple synonym of "homo sapiens". http://www.jewishvirtuallibrary.org/jsource/Archaeology/carmel.html talks about the caves of Carmel. The cave may well be "Skhul". http://www.archaeologyinfo.com/homosapiens.htm talks a lot about it, but doesn't talk of giants: "the site is an extremely important one" "The site has been dated from 120 kyr up to 40 kyr by various methods" "This led to the false impression of large cranial capacity". Notinasnaid 10:28, 21 April 2006 (UTC)

It was made up, there never were any race or species of "giant" humans. -- Mac Davis] ⌇☢ ญƛ. 12:23, 21 April 2006 (UTC)

Start here: Mount Carmel, Israel and here WAS 4.250 12:39, 21 April 2006 (UTC)

How do I obtain a list of the richest person in Microsoft Access?

Let's say I have a database of people on earth that has following data fields:

• Continent: Asia, N America, ...
• Country: Australia, ..., Zaire, ...
• Province or State: ...
• City: ...
• Name: ...
• Net worth: ...

I want to know who is the richest person in each country's each province. And I also want to know where can I find him/her (which city). I think I can create a query like this:

Continent	Country	Province	City	Name	Net worth
Group by	Group by	Group by	do nothing	do nothing	Max

However, in Microsoft Access, you can only do:

Continent	Country	Province	City	Name	Net worth
Group by	Group by	Group by	Group by	Group by	Max

It results in a very long list also grouped by cities and names. I end up to have a list of the richest Johns, Marys, Toms, ... in each seaside little town. Can I fix it with some SQL commands? -- Toytoy 13:04, 21 April 2006 (UTC)

yea you can and i could help you with the commands. im just a little confused about exactly what you want, could you elaborate a little bit- like what tables you already have and what the different fields are. --modesty 17:04, 21 April 2006 (UTC)

I would switch to SQL mode in the query window and cut those extra 'group by' statements, that's what's throwing it off. Access usually accepts hand made SQL as well as anything.

One way you could do this is: (you seem to have some Access knowledge, so I'm skipping all the little details of building queries, linking and so on - let me know, and I'll add them in)

• First run a query, with Continent, Country and Province set to Group by, and Net Worth to Max. Don't include the City or Name fields at all. Save the query, I'll call it Max_Worth, which gives you the maximum net worth in every province -- with no name or city information.
• Second, start a new query. Add the base table, plus the Max_Worth query. Link the Continent, Country and Province fields from the base table and the Max_Worth query. Next, link the Net Worth field from the base table with the last field in the query; it'll be called something like MaxOfNetWorth. Add all the fields in the base table to the query; have all of them set to Group By.

That should give you a list of every field that matches the maximum net worth for their particular province, with all of the information you need. --ByeByeBaby 03:29, 22 April 2006 (UTC)

Could a planet succesfully orbit a black hole?

My understanding of black holes is that they are essentially stars that have mass so great that light/matter can't escape it's gravity. So essentially they work like vacuum cleaners sucking up anything that crosses within their gravitational threshold. Presumably this also would mean that their mass would continue to grow as would their gravitational attraction as they "hoover up stuff". All that said, could a planet (or planets) orbit a black hole safely as our planets orbit the Sun? Or would they gradually be pulled towards the black hole and consumed because of it's ever increasing mass?

I would imagine that the process of a star becoming a black hole would no doubt destroy any orbitting planets of the star, but even so I'm still curious in the hypothetical case. Thanks in advance. Gallaghp 15:21, 21 April 2006 (GMT)

By the divergence theorem, a spherically symmetric object of a given mass has the same external gravitational field regardless of its radius. If the Sun were replaced by a black hole with the same mass, all the planets would continue to orbit the same way. —Keenan Pepper 14:50, 21 April 2006 (UTC)

Yeah, that's the common but somewhat incorrect perception. Black holes aren't vacuum cleaners, their gravity works just like that of any other stellar body up until the Schwarzschild radius. That radius is much smaller than the average planetary orbit, so any object could orbit a black hole just as easily as any other stellar object. The thing about a black hole (but not limited to them) is that most of them probably have an accretion disc with matter that's been drawn into orbit. In that disc they'll bump into eachother and the energy loss to friction will lead to them falling in eventually. But the rules for orbiting a black hole are the same for any other object. (Except for within the Schwartzchild radius). --BluePlatypus 14:53, 21 April 2006 (UTC)

Actually, Gallaghp's question seems perfectly rational to me. I'm not sure that the two answers above me noticed that the question was asking whether a black hole's mass (and thus the Schwarzschild radius) continues to increase, which would thus endanger any orbiting planet. In the general sense, I would assume that the answer is 'yes, the mass will continue to increase and so...'. However, if, say, the Earth were to turn into a black hole, its mass would increase no faster than if it just stayed being the earth (with random meteorites adding to its mass). In fact, it would probably increase in mass slower, as the Schwarzschild radius would be inside the original radius of the earth (so some debris which would have hit the Earth would miss the black hole). — Asbestos | Talk (RFC) 20:15, 21 April 2006 (UTC)

In order to form a traditional astronomical black hole, it would have to be super-massive, which means it would have a much larger gravity well than a typical star and pull in passing objects from much farther away. However, I can imagine a period after which all nearby matter had been pulled in, and the black hole could then capture a passing planet (not sure why a planet would be just flying around the universe, but let's ignore that for now). This would be quite difficult to detect, since not only would there be no light given off, but the gamma ray jets associated with the accretion disk would also be absent. A gravitational lens effect could still be detected, however, on objects behind the black hole from our POV. StuRat 21:39, 21 April 2006 (UTC)

Actually I'm pretty sure that the capture of a planet by a black hole would release an enormous amount of energy. Some of it would be released as light when the planet was destroyed, outside the event horizon, by the tidal forces; that should heat up the matter to the point that it would give off quite a lot of light, unless the black hole were truly huge. Given a black hole so large that a planet could slip past the event horizon without being vaporized first (anyone care to figure out how big that would be?) I would still expect a massive energy release, but it might be in the form of gravititational waves, which are pretty hard to detect. --Trovatore 22:18, 21 April 2006 (UTC)

I don't think you are taking "capture" to mean the same thing I meant. I meant the planet would orbit in a stable manner, perhaps at a rather extreme distance, like billions, or even trillions, of miles. StuRat 01:01, 22 April 2006 (UTC)

Oh, I see. Sure, I don't see any reason that couldn't happen. Of course some of the planet's energy has to be dissipated the first time it approaches, or it'll just fly off again, but I suppose there are ways that could happen. --Trovatore 01:15, 22 April 2006 (UTC)

As I understand it, a light object on a nonintercepting course with another far more massive object, in space, will do one of the following things:

• If the speed of the light object is much less than the orbital speed at that distance, the light object will spiral inward and eventually collide with the massive object.

• If the speed of the light object is somewhat less than the orbital speed at that distance, the light object will spiral inward toward the massive object until the speed is sufficient for a stable orbit, and the light object will then enter that stable orbit.

• If the speed of the light object is exactly the orbital speed at that distance, the light object will immediately fall into a stable orbit. This, however, is extremely unlikely.

• If the speed of the light object is slightly more than the orbital speed at that distance, the light object will spiral outward until the speed is sufficient for a stable orbit, and the light object will then enter that stable orbit.

• If the speed of the light object is much more than the orbital speed at that distance, the light object will slingshot around the massive object in a parabolic path and then continue on it's way. In an extreme example, the deflection is so slight that the path of the light object appears to be a straight line.

So, 3 or the 5 cases would result in a stable orbit, eventually, again assuming there is no accretion disk in the way of all this happening. StuRat 01:39, 22 April 2006 (UTC)

No, in the simple case (no energy transfer), there is no "spiraling". The light object coming "from infinity", or more to the point having a speed at least equal to the escape velocity, will trace out a hyperbolic (or parabolic) orbit past the heavy object, and escape to infinity, unless the perigee of that orbit is smaller than the radius of the heavy object, in which case it will crash.

To get any other pattern, energy somehow has to be transferred between the two objects, or between the light object and other bodies in the system (moons, accretion disk, etc). I think this might be a plausible mechanism for energy transfer between the planet and the black hole: Tidal forces could act on the planet, changing its spin and therefore its angular momentum, and the angular momentum of the hole would have to change to balance the books, with a concomitant change in its rotational kinetic energy. But the precise calculations would get into general relativity and are quite beyond me. --Trovatore 01:53, 22 April 2006 (UTC)

I disagree. This isn't the way satellites behave and I don't believe it's the way planets behave either. If orbits were that unstable, nothing would remain in orbit for long. StuRat 19:39, 23 April 2006 (UTC)

No, it is the way satellites behave, essentially. The difference is that satellites are gravitationally bound to their primaries; that is, they do not have enough kinetic energy to escape. But a body coming "from infinity" always has enough energy to escape, because it had it to start with. Unless, as I said, that energy can be transferred to some other body.

Satellites don't "spiral" either. Their orbits, rather than the hyperbolas or parabolas traced out by bodies coming from infinity, are ellipses. They fall in to the point of nearest approach (perigee), and fall out to the farthest point (apogee), and repeat; unless there's an energy transfer, the perigee and apogee does not change from orbit to orbit. --Trovatore 19:48, 23 April 2006 (UTC)

One little postscript: According to our apsis article, in context, rather than "perigee", I should have been using "perinigricon". I think that's going to be one of my new "I just like saying" words, to add to "chupacabra" and "Tucumcari". --Trovatore 21:15, 23 April 2006 (UTC)

http://en.wikipedia.org/wiki/Methuselah_(planet) - If neutron stars, why not Black Holes? - G3, 07:00, 25 April 2006 (UTC)

Another postscript, for the record: What I write above is correct in the Newtonian case and will work as long as you don't get too close to the black hole. It appears that matters are somewhat different if you get within a few Schwarzchild radii of the hole, owing to relativistic effects. See #Black hole horizon problems below. (In the archives, might be in a different week, not sure.) --Trovatore 02:52, 26 April 2006 (UTC)

Vacuum Extraction

Hello, I've heard of a procedure I'd like to find out more about, apparently Vacuum Extraction is "a new method of non intrusive exploratory digging without the risks associated with normal digging. In the USA legislation has been passed preventing mechanical digging due to costs associated with litigation following damage caused to underground pipes and cables. The method of exploration starts with high pressure water making a hole of up to 8 cms and a vacum system that draws out the debris The cable avoidance ground radar identifies hazards before damage occurs. The waste is held in a tank to be used as back fill or disposed of at water treatment plants if necessary." All I've been able to find on google under Vacuum Extraction relates to a medical procedure used in childbirth so I wonder if this is known by another name. Can anyone help me find out more about this method of digging? Thanks. AllanHainey 14:33, 21 April 2006 (UTC)

Vacuum excavation? It seems to give a lot of hits. --BluePlatypus 14:45, 21 April 2006 (UTC)

This method sounds like it would have some limitations, especially when dealing with underground water. Only 32 feet/10 meters of water can be supported by a pure vacuum, so a hole with water at more than that depth (or any depth of water continuously leaching in from the sides faster than the vacuum can remove it) would be an impassable obstacle. As a practical matter, the pump impeller would cavitate and fail at far shallower depths. A traditional drill would have no trouble with the water, and could actually benefit from the cooling. I would also think sharp chunks of quartz and such would damage the vacuum, or at least wear it out quickly. StuRat 21:06, 21 April 2006 (UTC)

We call this 'daylighting' over in the boonies of Ontario. It's only for shallow excavations around existing pipes and such. There is no reason to go deep. --Zeizmic 23:56, 21 April 2006 (UTC)

You don't necessarily have to suck from the surface. You could always pump compressed air or liquid down to push the dirt out. Alternately, you could build the pump into the drill head, and again push from the bottom rather than pulling from the top. Of course, as Zeizmic says, this technique is really only used or likely to be useful for shallow work. If you're going to go deeper than pipes or cables are buried, then you can switch to conventional drilling equipment once you've got the first few meters of hole opened up. TenOfAllTrades(talk) 03:24, 22 April 2006 (UTC)

Martial Arts feats

I have seen buddist monks, martial artists, and other assorted people stand on very sharp things (i.e. a sharp edge of a katana) and not be cut by them. Similarly, I have seen people stand on a single sheet of rice paper without breaking it.

Is it some kind of trick, or are they really able to do it? Is they are, how? I'm not into 'Ki' or 'Qui' or whatever the popular word is for it now; I would prefer a scientific explanation above all else.

Thanks! 68.52.56.111 15:30, 21 April 2006 (UTC)

Hmm, I know it's possible to support your weight on a lot of sharp things together, like a bed of nails, but not a single sharp thing by itself. Were they standing on a whole bunch of katana, or just one? Also, if a sheet of rice paper is curved just the right way, it might spread the forces out and support the weight of a person. By the way, it's spelled qi in pinyin. —Keenan Pepper 15:40, 21 April 2006 (UTC)

Similar to this monk. Unfortunately, I can't answer your question. Thank me for being useless. --Chris 16:48, 21 April 2006 (UTC)

I was actually present when a guy (martial artist, cannot attest to the style though) stood with his feet on two katanas. How do I explain this...eh...he stood where the two blades of the katanas were both hitting his feet, as if he were standing on two telephone wires that were next to (parallel to) each other. So I guess the force could have been spread out along both of the katanas. I cannot verify the sharpness of the katanas to you, but he had what I assumed was a Aikido, Iaido, or Kenjutsu (or the like) practioner do a tameshigiri on some rolled up bamboo poles with both of them before he stood on them. Maybe that's the secret to it - he had something in the mats to secretly blunt the swords. However, if the guy was on the up and up, I would like to know how he did it. Thanks. 68.52.56.111 18:45, 21 April 2006 (UTC)

Some thoughts:

• The bamboo was probably struck at high speed with the swords, while his feet were only slowly placed on them. Thus, a much greater force was applied to the bamboo. Perhaps, even impact force was applied to the bamboo by the high speed.

• The bamboo might have also been considerably softer than it appeared, say if it had been soaked in something to make it pliable and/or cut most of the way through.

• He may have had thick callouses on his feet, making them much tougher than they appeared.

StuRat 20:50, 21 April 2006 (UTC)

Seperating Chemicals

I noticed that in my first aid kit there are electolyte tablets that have 220 mg of NaCl, 15mg of KCl, and 18mg of CaCO2. Just out of curiosity, how would I got about seperating these 3, especially the NaCl from the KCl? --Chris 16:48, 21 April 2006 (UTC)

The CaCO₂ is easy. Just dissolve the tablet in water and it will precipitate out, especially if the pH is raised. Separating Na⁺ from K⁺ is much harder. Chromatography and ion exchange come to mind... —Keenan Pepper 17:10, 21 April 2006 (UTC)

[This http://www.corrosion-doctors.org/Biographies/DavyBio.htm] is interesting. It indicates that Humphry Davy developed a method back around the beginning of the 19th century to separate potassium from sodium. It used the fact that sodium perchlorate is soluble in 97% ethanol whereas potassium perchlorate is not. (You're going to need perchloric acid, ethanol, and patience....)

A technique used commmercially is called recrystallization. Again, it relies on manipulating the relative solubilities of the potassium and sodium salts. Starting with a room-temperature saturated solution of sodium and potassium chlorides, add your mixture of salts and heat to high temperature; mix until no more powder dissolves. The solubility of NaCl in water is very nearly constant regardless of temperature, whereas the solubility of KCl increases substantially when the water is heated. Consequently, adding your powder to the hot solution will dissolve KCl and leave powder enriched in NaCl.

Step two is to filter this solution to collect your NaCl-enriched powder from the hot solution. Step three is to cool the solution back to room temperature. The excess dissolved KCl will precipitate; you can collect it by filtration. TenOfAllTrades(talk) 03:18, 22 April 2006 (UTC)

I assume it's CaCO3 that's meant? --BluePlatypus 17:27, 21 April 2006 (UTC)

Hmm, right, wonder why I didn't notice that. CO₂²⁻ would be the impossible ion carbonite. —Keenan Pepper 17:36, 21 April 2006 (UTC)

Yes, CO₂²⁻. Carbonate... sorry. --Chris 21:10, 21 April 2006 (UTC)

History of psychiatry

Hello, I've been wondering about one specific topic : the evolution of the concept of late schizophrenia. European nosology (early 20th) used a specific concept : "psychose hallucinatoire chronique" (PHC) that is still widely used in France for instance. Modern nosology only uses the concept of late schyzophrenia...so here are my questions :

• is late schyzophreia an accurate replacement concept for PHC ?
• how to explain that despite the DSM-4 and CIM-10, that specific concept of PHC is still used ?

So if you guys have any link / reference article / answer / suggestion... it would be greatly appreciated !

Alkaline seafood dishes

Is lutefisk the only alkaline seafood dish? I remember reading somewhere that most cultures developed acidic seafood dishes (e.g. Western fish with lemon, Japanese sushi with vinegar...) because that converts the amines like cadaverine and putrescine into their ammonium salt forms and thereby reduces the rotten fish smell. How come the Scandinavians didn't catch on to this? —Keenan Pepper 17:18, 21 April 2006 (UTC)

Perhaps not the only, but probably the most alkaline. :) Lutefisk isn't rotten and doesn't smell much though, that's Surströmming. They do eat acidic fish too, in the form of pickled herring. Between the salting, smoking, drying, drying-with-lye, pickling and fermenting.. I think they pretty much used up every form of preservation available to them. My guess is that if they had had vinegar, they would've pickled the herring instead of fermenting it. --BluePlatypus 17:42, 21 April 2006 (UTC)

Seahorses!

Hi. I am doing a project on seahorses in my marine biology class. I was wondering what the digestive, skeletal, and circulatory systems were for seahorses. Can someone help me out? Thanks for your time!

I hate to sound so much like the others...but try searching for 'Seahorses' on Wikipedia, perhaps?

-I already did, but it didn't say anything about the systems...thanks anyway.

Try this Google search --LarryMac 19:35, 21 April 2006 (UTC)

18 months back I visited a seahorse farm in Port Lincoln, South Australia, and afterwards did some of my own research on the syngnathidae. The folks at syngnathid.org were really helpful (so I now know sea horses have only one “kidney”, without glomeruli, on the right side – wow!). The site is dedicated to info about these creatures, mainly related to their breeding in captivity, with the aim of conserving wild populations. Collectively they have thorough knowledge of the sea horses' normal and pathological structure and function. Try asking on that site; people who are fanatic about conservation (in a good and necessary sense) are usually good for asking questions of, since their main weapon is education. --Seejyb 20:42, 21 April 2006 (UTC)

Lucid Dreaming

Is it possible to induce lucid dreaming with a tape recording that says "YOU ARE DREAMING" over and over?

Sounds like an experiment! Melchoir 21:21, 21 April 2006 (UTC)

It would work for me, I know in light sleep, I can hear what is going on while I am sleeping at times. Good experiemnt. See if the Lucidity Institute has done it before. -- Mac Davis] ⌇☢ ญƛ. 03:24, 22 April 2006 (UTC)

I would think something like a taped conversation or animal sounds would be more likely to start a dream. Physical sensations also seem able to cause a dream, like a bandage (or "plaster", for the Brits) once made me dream I had a leach on my arm. StuRat 04:55, 22 April 2006 (UTC)

The point is not to start a dream, but to start a lucid dream (which the OP helpfully linked above). Melchoir, as I recall, this isn;t so good, as your brain will eventually tune out the sounds of the tape if its keeps hearing the same thing. People who use tapes usually try to time the voices to come on when they expect to be in REM sleep, somewhere around 90 minutes after you fall asleep. If you look online, you'll find all the common methods (looking and your hands and stuff) that are pretty tried-and-true. — Asbestos | Talk (RFC) 23:05, 22 April 2006 (UTC)

Government Suppression

Is there any eveidence besides reviewing endless lists of patents, to understand, or gain information about, how the government exercises an ability to suppress technological innovations, certain inventions, or scientific data to control the public more than it should. I'm not trying to be some conspiracy theorist, but I have already found astonishing evidence about things I can barely believe in relation to the vagueness listed above. Anyone can go and read some writing about or by tom bearden to see a little bit of what i mean. I can understand the implications of monopolies blah blah and all that. but when something has the potential to beifit all of mankind in profound ways then why else does this seeming oppression prevail?

and does anyone know what this means: e=±((square root symbol) since i couldn't find it)α(multiplied by something that looks like an h with the stem(top part)crossed through with a small line)finally multiplied next by c (the speed of light of course) lastly maybe someone can give me a vague explanation of non-linear optic effect

Retrieved from "http://en.wikipedia.org/wiki/Wikipedia:Reference_desk/Miscellaneous"

This has been taken up over at Misc. --Zeizmic 23:48, 21 April 2006 (UTC)

Absolute pitch

I _need_ an absolute pitch. It can be developped. Has anyone got any idea about how to/the best way to attain this target? Thanks. —The preceding unsigned comment was added by 85.50.33.189 (talk • contribs) 21:53, 21 April 2006 (UTC)

You're one up on me if you have information that absolute pitch can be learned; I always thought you pretty much have it or you don't. Certainly, you can learn some tricks for approximating absolute pitch (for example, learning how particular notes feel in your throat), but I don't think that's quite the same thing.

Absolute pitch is a mixed blessing for a singer anyway; good relative pitch is much more useful IMO. Absolute pitch can be a particular handicap to an ensemble singer, as it can make it difficult for him to match pitch with the rest of the group. --Trovatore 22:33, 21 April 2006 (UTC)

Holy cow batman! We actually have an article on Absolute pitch! --Zeizmic 23:52, 21 April 2006 (UTC)

It is entirely possible to learn absolute pitch. The problem is that it is generally considered impossible after the age of Five. This is not true for all people, but is a good standard to go by. Unless you are asking on behalf of your child or a younger person who falls into the "under age Five" category, I would assume that you are over such age, and not in that category, so it may be impossible for absolute pitch to be attained. yaninass2 04:55, 22 April 2006 (UTC)

It's not as difficult as you think. For me, I can always sing a C to myself, without reference. Using that alone, I can simply relatively pitch other notes. It's not like you need to be able to recognise every note. I think I read about studies which showed that if people listened to a particular song many, many times, then whenever they sung the song to themselves, they would sing it in the correct key, without reference. However, that was only after a lot of listens. So I'm pretty sure it can be learnt through intense practice. As far as I can remember, that's how I seemed to develop it. -- Daverocks (talk) 05:27, 22 April 2006 (UTC)

Yup. From years and years and years of tuning my guitars, I know the pitch of 440Hz by "instinct". -- Branden 20:43, 24 April 2006 (UTC)

April 22

Cannabis cultivation

I have recently become interested in botany and I was wondering - in regards of the cannabis plant - how do I distinguish the female from the male? Regards, Gardar Rurak 02:13, 22 April 2006 (UTC)

Erowid should have all the answers you need on their Cannabis cultivation page, specifically these two illustrated articles linked from it. Also, you may be interested in our Cannabis (drug) cultivation article. --Aramգուտանգ 02:59, 22 April 2006 (UTC)

• And just why do you want to know? A Clown in the Dark 03:05, 22 April 2006 (UTC)

Perhaps he's investigating traditional methods of making hemp rope, and wants to make sure there's no THC in the final product, so he needs to know which ones are female so he can discard them :) Remember, assume good faith. --Aramգուտանգ 03:23, 22 April 2006 (UTC)

Yes - I'm starting a hemp shop selling hemp-tshirts and hemp-slippers and I need to sort out the products of the evil one. Thanks or the reply, it's very informative. Gardar Rurak 03:45, 22 April 2006 (UTC)

Yes, and I'm sure you will burn the evil ones. Of course, to ensure proper fire safety, you will need to burn them in small quantities. These small quantities should be in wrapping papers to properly contain the fire, and you will need to pull air over the marijuana by inhaling at one end of each unit for proper combustion. Your devotion to fire safety is admirable ! StuRat 04:45, 22 April 2006 (UTC)

If he really wants to make hemp rope, he should read the hemp article. The proper way to make hemp would be to cultivate the right variety and to use the right part of the plants. this would ensure the final product contains no THC far better then using only males plants (not to mention he won't be very successful if he discards all female plants since he will need to grow more plants which he can't do if he destroys one sex). However it is common practice to remove male plants to increase the amount of THC. If he wishes to do so I really couldn't give a damn but he should be honest or at least not lie about his intentions. If he does wish to lie, and you wish to help him, at least come up with a more plausible lie that actually makes sense. Nil Einne 05:22, 22 April 2006 (UTC)

If you're worrying about male and female plants, maybe you've already been around cannabis too long. Peter Grey 04:52, 22 April 2006 (UTC)

Take it easy... I got an answer to my question and everything was all dandy. Look, I live in a society where it is legal and acceptable to grow these plants for personal use so I see no reason why I should lie about it which was indeed never my intention. I realize sarcasm is not easily communicated through text and may not be as prevalent in other cultures as a form of humour - that is regrettable and for this I do apologize. I have previously made my own beer, wine and alcohol - now I want to try this - it does not mean that I am an alcoholic or a pothead - in fact I rarely even drink coffee much less alcohol or pot. Still, as a hobby it's a lot more interesting than sitting on your ass watching sitcoms or collecting stamps all day. You can judge me all you want - that's your business. Gardar Rurak 06:45, 22 April 2006 (UTC)

Since you are out of the Nasty States, you can grow small amounts for personal use (or you have a medical permit). I had fun with that for a while. There are lots of seed shops. Get the best hybrid you can afford. Put the seeds in little peat seed cups to start. Lighting is the toughest thing to get right. You also have to go through 2 generations to get a good crop, by eliminating the males, and taking cuttings from the females. I don't smoke, and followed the recipes for heating in olive oil, but shortly I started reacting with migraines, and gave it up. --Zeizmic 12:51, 22 April 2006 (UTC)

Price of medicines

I noticed this in the U.S.-Australia Free Trade Agreement#Pharmaceutical Benefits Scheme 2 article:

The scheme involves subsidy of the price of certain "listed drugs", with the result that consumer prices for many common medications are a great deal cheaper than elsewhere in the world.

It sounds to me like this claim is most definitely wrong. AFAIK, while the price of these common medications are cheaper then in the US and in other countries without subsidy schemes, the prices are comparable (definitely not a great deal cheaper) then the prices in other countries with similar agencies that subsidy and negoiate for cheaper drugs, e.g. NZ, UK etc. Can anyone confirm this? Nil Einne 05:01, 22 April 2006 (UTC)

Stars on the southern cross - why do some have 7 points and one has 5 points?

I have been researching the stars of the southern cross, and was wondering why,when you draw these stars on things such as the Australian flag, are the four main stars (Alpha crucis, Beta crucis, Gamma crucis, Delta crucis) represented as 7 pointed stars, and the smaller (epsilon crucis) is represented as a 5 pointed star?? I am guessing it has something to do with double stars and red dwarfs, but I was wondering if there are conventions for this and where I can find info about the rules when drawing a star? Thanks for your help!!

I would guess it's just a way to differentiate between the brighter and dimmer stars. StuRat 08:30, 22 April 2006 (UTC)

The seven points on the stars on the Australian flag represent the number of states and territories present at Federation (six states, and one point representing all territories). I'm not sure what the 5-point star is meant to represent, and I'm not aware of any specific conventions for drawing stars. Our article on Flag of Australia has a lot of information you might find useful. -- Daverocks (talk) 08:35, 22 April 2006 (UTC)

The 6 states and the territories are represented by the 7-pointed large Federation Star (or Commonwealth Star) beneath the Union Jack, not by the stars in the Southern Cross itself. To quote the article:

• "The number of points on the stars of the Southern Cross on today's Australian flag differs from the original design in that the stars varied between five and nine, reflecting the relative brightness of each in the night sky. The British Admiralty, to increase ease of manufacture, standardised the Southern Cross by giving the four biggest stars seven points and five for the faintest Epsilon Crucis. The Commonwealth Star originally had only 6 points, representing the six federating colonies. However, this changed in 1908 when a seventh point was added to symbolise the Territory of Papua." JackofOz 09:03, 22 April 2006 (UTC)

All a bit silly really. As everyone knows, the main four stars only hav five points each (and you can ignore the fifth one :). As far as the Aussie flag is concerned though, as Jack (there's an ironic name, considering the topic) points out, the points represent the states and territories. Originally Alpha Crucis was given nine points, Beta eight, and so on down to epsilon with five. When the flag was altered in 1908, the four larger stars had the number standardised to seven. The number of points on the smallest star remained at five, possibly for ease of manufacture rather than any more esoteric reason. You might also like to check out the Flags of the world website, which has considerably more information. BTW, Australia is not the only country which has an unusual number of points on its stars for the purposes of representing subnational regions. Malaysia and the Marshall Islands are two others which spring to mind which also do this. Grutness...wha? 10:27, 22 April 2006 (UTC)

Grutness, I hate to disabuse my trans-Tasman cousins, but you seem to have somewhat confused the New Zealand flag and the Australian flag.

• The NZ flag has four stars in the shape of the Southern Cross. All four stars have 5 points.
• The Aussie flag has six stars. The smallest star Epsilon crucis has 5 points, and all of the remaining stars have 7 points.
• The Aussie Southern Cross comprises 5 stars: four of 7 points and Epsilon crucis.
• There is a separate Commonwealth Star that appears beneath the Union Jack (I could almost call it the Union JackofOz)
• The stars in the SC do not represent anything other than themselves.
• The only star on the flag that represents the states and territories is the Commonwealth Star. JackofOz 03:00, 23 April 2006 (UTC)

Please read what I wrote. I mentioned that when the Australian flag was changed, the four largest stars of crux had the number of points changed to seven. The Commonweatlth Star was also changed from six to seven points at that time. Since the question referred to the stars of Crux without reference to the Commonwealth star (which is symbolic and has no astronomical significance) I did not refer to it in my answer. The reason for the change of all these stars was to represent the seven regions of Australia (the six states and the territories). Perhaps if the Aussies had chosen a recognisably different flag in the early years of the 20th century rather than one attempting to copy a flag that has been used in New Zealand since the 1860s, the confusion wouldn't have arisen ;) Grutness...wha? 09:43, 24 April 2006 (UTC)

I did read what you wrote, which was what prompted my response. True, the question referred only to the Southern Cross and not to the Commonwealth Star. But it did say "why do some have 7 points and one has 5 points" and it did specifically mention the Australian flag. Since the New Zealand flag has no stars of 7 points, clearly the question had nothing to do with the New Zealand flag and was was referring only to the Australian flag. Nevertheless, you wrote: "As everyone knows, the main four stars only hav five points each". This statement would be true only if you were talking about the NZ flag. But you never stated you were talking about the NZ flag, which is why I thought you must have been confusing it with the Australian flag. I still think that.

It is not true that "The reason for the change of all these stars was to represent the seven regions of Australia (the six states and the territories)". Please re-read my italicised quote above from the Wikipedia article on the Oz flag. The reason for the change to the stars in the Southern Cross was "ease of manufacture". The only star that has ever represented the states or territories is the Commonwealth Star. If you disagree with any of these statements, you're free to change the article, but expect such changes to be quickly reverted unless you can provide references.

Re the design itself, and its frequent confusion with the NZ flag, I couldn't agree more that a new design is well and truly overdue. Of course, both flags would need to change, because if we change and NZ doesn't, people will still look at the NZ flag and think it's the Oz flag (and vice-versa). And if we change first, don't you Kiwis dare copy us !!  :--) JackofOz 10:03, 26 April 2006 (UTC)

oh dear. The original title, as stated in the heading, did not mention Australia (although it was mentioned later in the repeating of the question). But it would be nice if you could work out what a smiley refers to. And if the Wikipedia article states that the only reason for the change was ease of manufacture, then it is wrong. The number of stars was brought into alignment at the time the Commonweath Star was increased to a seven-point star. As such, they were changed to seven points primarily because the Commonwealth Star was changed. Ease of manufacture was a reason - but it it had been the primary reason then the number of points would have been either six or five - a far easier number of points for a flag maker to manufacture that seven. thereofore, the reason why they are seven point stars rather than some other number is because of the states and territories.

Personally I wish the Federation Flag hadn't been so politically charged at the time of confereation. It would have made a far more attractive national flag. Grutness...wha? 08:21, 27 April 2006 (UTC)

work, energy and power

How much is the power required to raise 300 liters of water per minute through a height of 6 m using a pipe of diameter 2.4 cm if acceleration due to gravity is 10m/s*s ?

Per guidelines that are up at the top of the page, we don't answer homework questions here. Otherwise, it would be a homework help desk. What forumlae and knowledge can you apply? Did your teacher tell you anything in class about hints to solve it? I'll hint you some. You'll need to know the weight of the water through w=mg. Check the water article for its mass, and convert. Apply the formulas at work and power. Your angle is 90 degrees. The pipe diameter doesn't matter, its there to fool you. Good luck ;) -- Mac Davis] ⌇☢ ญƛ. 07:19, 22 April 2006 (UTC)

Pipe diameter is important if you're worried about frictional losses. All else being the same, it takes less effort to move water through a large-diameter pipe than a small-diameter one. --Serie 22:37, 25 April 2006 (UTC)

Light

A spherical soap bubble of radius 2cm attached to the outside of a spherical bubble radius 4cm. What is the radius of curvature of the common suraface?

Per guidelines up at the top of the page we don't answer homework questions here, otherwise it would turn into a homework help desk. See this for help. -- Mac Davis] ⌇☢ ญƛ. 07:21, 22 April 2006 (UTC)

If the header is anything to go by, the answer is about 300,000 km/s. Grutness...wha? 10:35, 22 April 2006 (UTC)

Bound charge density

Can anybody tell me what is the bound charge density for a uniformly polarized sphere.Is it zero?Thanks!

Need more info. Solid sphere? Hollow? Conductor/insulator? Isopropyl 15:54, 22 April 2006 (UTC)

For a solid sphere.Thanks.

Well, you should look up bound charge (which redirects to polarization but does discuss it properly). Then you should think about what "uniformly polarized" means, and apply the formulas. But make sure to consider the surface of the sphere separately, if you care about the surface: assuming that there is nothing outside the sphere, the polarization is certainly not uniform when there's a sphere on one side of you and vacuum on the other! --Tardis 19:30, 22 April 2006 (UTC)

Centre of Gravity

this might sound adsurd to ask but why is a 4 legged stool more stable than a 3 legged stool? I think it has something to do with the centre of gravity.

That depends on how you define "stable". If you have an identical stool and you mount four legs on it rather than three, it will be less stable. The reason for this is that a tripod (three legs) is always stable on nearly any surface (try it!). A four-legged stool will always have one leg free in the air on any surface except a perfectly flat one (assuming the four legs are equally long). — QuantumEleven 14:07, 22 April 2006 (UTC)

It does indeed depend on what you mean by stable. Quantum's answer assumes that it means "not wobbly", whereas I think the questioner means "unlikely to fall over", which is different. With the latter definition, the stability of an object can be defined as the angle by which you need to tilt it before it falls over. This is the angle at which the object's centre of gravity ceases to be above the object's footprint. The further the COG has to shift sideways before it falls outside the footprint, the larger this angle and therefore the more stable the object. A three-legged stool has a triangular footprint, while a four-legged stool has a square one. Take two stools of the same seat size, one with three legs and the other with four, and draw their footprints - a triangle and a square. You will find that the distance from the centre of the triangle to the nearest point on any edge is shorter than the corresponding distance for the square. So, the COG of the three-legged stool has less far to travel to the edge of its footprint than the COG of the four-legged stool. In turn, this means that the three-legged stool has to tip through a smaller angle than the four-legged one before it falls over. This makes it more less stable. --Heron 17:18, 22 April 2006 (UTC)

That's an excellent response, although I think you meant to say that the 3 leg stool is "less stable", at the end. Another "stability" concern is the ability to resist tipping over if one or more legs collapses. With a 3 leg stool, losing any one leg will cause it to collapse. With a 4 leg stool, if the CG remains above the triangle formed by the remaining 3 legs, which is basically a 50/50 shot, then it will remain upright. 5 or more legs would make it even more stable (with 5 legs, any two legs could fail without causing the stool to collapse). So why don't stools typically have more legs ? That would add expense and weight and chair legs don't collapse all that often. Also note that the wobble problem with more than 3 legs is easily fixed with rubber feet on the stool, which will, in effect, adjust the height of each leg (within limits), to compensate for a lumpy floor. 3 leg stools also typically spread the legs out farther than 4 leg stools, to compensate for the "tippiness" inherent in a 3 leg design. The inherent instability of 3-wheel ATVs (all terrain vehicles) actually led to them being banned in many places due to fatal rollover crashes. 4-wheel ATVs are much safer. StuRat 18:27, 22 April 2006 (UTC)

Minor point: a uniform stool with five legs in a regular pentagon arrangement would fall over if two adjacent legs were lost. --Tardis 19:50, 22 April 2006 (UTC)

Well, yes. But you could have a regular square stool, with the fifth leg in the center. GeeJo ^(t)⁄_(c) • 14:12, 23 April 2006 (UTC)

Which would be essentially just as stable as a 4-legged stool.  freshgavinΓΛĿЌ  05:50, 26 April 2006 (UTC)

I disagree. If such a stool lost two adjacent outside legs, you would still have a tripod supporting it, especially if the legs broke off and thus their weight is no longer counted toward the CG of the stool. Note, however, that it would be an off-center 90-45-45 triangular base, not a 60-60-60 base. But, if you were careful how you sat on it, you could still make it work. StuRat 18:24, 26 April 2006 (UTC)

Photon mass

Photons are massless, but according to E=MC^2, if photons' mass is 0, 0 times the speed of light squared is also zero. how about its energy? photons have energy i think? (2nd part of question moved to next section below.)

Photons have some amount of mass; see photon. As for atoms, see electron configuration for an overview of orbital theory. Isopropyl 13:51, 22 April 2006 (UTC)

The E=mc² equation is actually a simplification of Einstein's result. You can start at Energy-momentum relation for more details. Essentially, there is another term that relates to momentum and not just mass; this is where the energy of a photon is represented. (Despite having a zero rest mass, photons do indeed have momentum.) TenOfAllTrades(talk) 13:53, 22 April 2006 (UTC)

hmm, photons aren't massless for one thing--152.163.100.74 20:32, 22 April 2006 (UTC)

Photons are quite massless; I don't know where you and Isopropyl are getting that. Melchoir 20:40, 22 April 2006 (UTC)

Photons are exactly massless. The formula E=mc² relates the energy with mass of a massive particle in its rest frame where its momentum is vanishing. However in the case of a zero mass particle, this rest frame simply doesn't exist (a photon never has zero momentum)which forbids one from applying this formula to the photon. For a photon propagating with pulsation w then its energy is given by E= hcw² with h the Planck constant LeYaYa 21:22, 22 April 2006 (UTC)

What's pulsation? If you mean angular frequency, the formula is

$E=\hbar c\omega .\,$

If you mean ordinary frequency, the formula is

$E=hc\nu .\,$

Nothing is squared. Melchoir 21:58, 22 April 2006 (UTC)

All of the posters above are correct, but are defining "mass of a photon" differently. Photons have zero rest mass, but nonzero relativistic mass. While it can be argued that talking about the "rest mass" or "relativistic mass" of an object (like a photon) that moves at C isn't terribly meaningful, it's useful if you want answers to questions like this one.--Christopher Thomas 03:01, 24 April 2006 (UTC)

Atomic Model

My chemistry teacher says that electrons orbit around the nucleus, and my physics teacher says taht it would lose energy if it does. How does the atomic model actually work?

I've split your question in two, hope you don't mind (makes it easier to answer). Have you read our excellent article on atoms? The short answer is that "electrons orbiting around a nucleus" (in the manner of planets around a sun) was a model of the atom used a long time ago (I seem to recall that it was developed by Niels Bohr, but I could be wrong), and while it's not technically correct per se (your physics teacher is correct, electrons orbiting a nucleus would lose energy and spiral in), it's a useful model for much of chemistry, as, below a certain level of complexity, it can explain effects observed in chemistry perfectly well (in school, it usually lasts until the last years of high school). As for what 'really' happens in an atom, things get a bit hairy... electrons behave in very strange ways, a bit like particles and a bit like waves (check out wave-particle duality if you're interested). Because of the Heisenberg uncertainty principle, we can never know exactly where an electron is, only that it's somewhere near the nucleus. Take a look at the picture at the top of atom - the dark regions (called orbitals) around the nucleus (the dot in the middle) are the regions where the electrons of a Helium atom are most likely to be found, but we don't know where in that region they are at any one time.

You'd be right to think that this is all very odd - it is. Also, I've greatly simplified things, if you're interested in more detail, ask again, and I'm sure someone with better knowledge of the subject will be able to help you. Have you tried asking your two teachers to sort out their apparent contradiction...? :) — QuantumEleven 14:04, 22 April 2006 (UTC)

As indicated above, the "real" answer (where real is the best current understanding, not an ultimate truth) is very complex, as well as counterintuitive making it hard to understand. Your chemistry teacher is using a model of the atom that is sufficient to explain most of chemistries dealings with atoms and electrons, probably the Bohr model, without burdening the class with the hard math and strange effects of quantum mechanics. Your physics teacher appears to have started on explaining quantum mechanics, and has indeed touched one of the primary reasons the theory was developed in the first place, because before it no satisfying atomic model existed. SanderJK 14:29, 22 April 2006 (UTC)

I would assume that the physics proffesor in question is probably explaining simple waves, accelerating charges around a point mass, etc... probably EM waves, but no quantum mechanics at all. am I right? and the bit about electrons falling into a nucleus is probably just a throw away example about moving charges generating waves? something about how if the classical model of the atom were correct atoms would just generate bright EM flashes then disappear into nothingness?--152.163.100.74 20:40, 22 April 2006 (UTC)

Actually, the planetary model is insufficient for chemistry. How can it explain bonding? A decent chemistry class will have much to say about quantum-mechanical orbitals. Melchoir 19:52, 22 April 2006 (UTC)

Well, it's true that the electrons would lose energy if they orbited the atom - if you described them as moving charged particles in the classical physics context. However, classical physics don't work on the atomic scale. You need quantum physics for that. Now, from the quantum physics viewpoint, the electrons do orbit the nucleus moving in what's called 'orbitals' - unlike in classical physics they can't have any energy, only certain discrete energy levels which each correspond to a pattern of motion. Motion in this sense is a bit strange concept though. - The electrons have momentum and angular momentum and so on, but they don't "move" in the classical sense of following some trajectory. Rather, all you have is a "probability cloud", that is a given probability that the electron will be at some point in space. So in summary, yes they orbit the nucleus, but they don't do it in any way which is similar to what we usually mean by 'orbit' as in planets. --BluePlatypus 16:18, 22 April 2006 (UTC)

your general chem proffesor is just teaching you the classical atomic model, and your physics proffesor is doing the same thing, short answer, the classical model was wrong, they don't teach you that in general chem, because general chem is basically just a test to see what percentage of the premeds actually have the patience to get through a chemistry course, most don't, just accept that everything they teach you between your first semester of general chem, and your second semester of organic is basically over simplified material designed to catch up students who may not have ever taken high school chemistry, or come from regions of the country with inferior public education systems--152.163.100.74 20:37, 22 April 2006 (UTC)

In general most things in science have more subtle (or detailed or complex) explanations as you learn more. So you start out simple, then learn it wasn't quite right, and get better (but still not 100%) answers. if you continue to a PhD you'll be the one researching the answers.

The question here centers around the term "orbit". Usually we think of this in terms of classical mechanics, an object orbits, this requires a force, energy is lost in the system, the system winds down. Thats classical mechanics, and this was in fact not a trivial problem. It was the main problem with the "orbiting electron" solar-system type models.

In fact a more accurate model is that when you look at energy within an atom, you have to look at it via quantum mechanics not classical mechanics. In quantum mechanics, the electron is no longer seen as a solid particle, nor does it lose energy unless it moves out of its energy state, or shell. It's no longer a solid object circling, instead its a probabalistic wave-particle whose location is described by equations not by simple X-Y-Z co-ordinates. The "orbit" of an electron in quantum mechanics is a shorthand easy way to say the "energy-state" of that electron, and it doesn't lose energy so long as it doesn't change state.

Your chemistry teacher doesn't need you to know these complexities, so he is simplifying it. Your physics teacher is trying to touch on them without confusing people. Hence you get 2 different views. FT2 (Talk) 03:07, 26 April 2006 (UTC)

What experiments can I run of a polluted water sources (e.g collected from a heavily polluter river)?

At the beginning, i would like to say sorry to all users that i ask the question such directly since i am in hurry, please forgive my rudeness. Question:

Can any Wikipedia users give me some suggestions of experiments or test that i can do unto a pulluted water sources in a simple secondary school laboratry. My teachers do have some suggestion to me:

Listed below: 1.dissolved oxygen 2.quantity of chlorin ion,phosphate,magnesium ion

However, my teacher told us that if we can run extra experiments that beyond his suggestion list, then we can possiblely score a higher marks in this assessment. By this reasons, i am here to please for your helps to suggest some others experiments that i can carry out. If it don't touble you please also give the steps and equipments require for your sugested experiment. Please remenber that my school's laboratry is not quite well equiped.Thanks~

Timmy Ho From Hong Kong

A simple litmus test can give you the relative pH of the water. It's not too difficult and the supplies are cheap. Isopropyl 15:52, 22 April 2006 (UTC)

You could boil off the water and mass the remaining material. Really cheap and easy. Leonardo 16:16, 22 April 2006 (UTC)

Shake it vigorously, and watch for the formation of suds. These are a good indication of certain types of pollutants, such as phosphates. Compare how long it takes the suds to dissipate with an unpolluted control sample. StuRat 18:03, 22 April 2006 (UTC)

weight on planets

suppose you weigh 50 kilograms, or about 110 pounds.What would you weigh on Mars.

The same, if your scales were calibrated correctly. --Heron 17:23, 22 April 2006 (UTC)

No, you'd have the same mass if your scales were calculated correctly. You'd still have a mass of 50 kilograms, as a kilogram is a unit of mass, but you'd no longer weigh 110 pounds, due to the lower gravity. Our article on Weight has a handy table of interplanetary conversion factors, and a weight of 110 pounds on Earth (I'm assuming this part -- if you weigh 110 pounds on, say, Jupiter, the answer is different) would weigh 0.377 times as much on Mars which is about 41.5 pounds. Our Weight article has a very good description of the difference between weight and mass, if you're confused about that bit. --ByeByeBaby 17:54, 22 April 2006 (UTC)

(Edit conflict) That's not true. Weight refers to the force exerted by gravity, so that changes on different planets. The confusion here is because 50 kilograms is a unit of mass, which does not change from planet to planet. So if you weigh 110 pounds, according to this page, on Mars you would weigh 41.5. (In proper metric units, you used to weigh about 490 newtons, and now weigh about 180. It's a bit confusing that many places using metric units refer to peoples' "weights" in units of mass.) -- SCZenz 17:56, 22 April 2006 (UTC)

My answer was deliberately oblique because I didn't want to do the questioner's arithmetic for him. Besides, I was making the semi-serious point that scales on Mars should either read mass in kilograms, or force in newtons. Imagine you're a cook in a Martian colony. You would want a kilogram of potatoes to register "1 kg" on the scale, not "377 g". After all, you want to know how many stomachs they are going to fill, not how heavy they feel. If the scales corrected did not correct for the difference in gravity, then recipes would all have to be different depending on the planet you were on. (Or they could all be translated into moles, which would be even weirder.) Our attempt to colonise the galaxy would collapse in confusion, I tell you! --Heron 18:47, 22 April 2006 (UTC)

If you weigh 110 pounds, you belong either in school or in the kitchen; since neither institution is available on Mars, the question is moot. (runs away) Melchoir 20:06, 22 April 2006 (UTC)

If we're getting into terminological exactitude, bear the following in mind. When a person says "I weigh 100 kgs on Earth but only 37.7 kgs on Mars", they're really saying:

• My mass is 100 kgs (everywhere in the universe).
• My weight here on Earth at sea level is 100 kgs weight.
• My weight on Mars would be 37.7 kgs weight". JackofOz 02:30, 23 April 2006 (UTC)

If we're really getting into terminological exactitude, bear the following in mind. When a person says "My mass is 100 kgs (everywhere in the universe).", they're really saying:

• I have certainty that the laws of physics as presently understood can be safely extrapolated to all places and contexts of all kinds, both known or unknown.
• I can ignore relativity, or I never travel, or I confuse rest mass with mass :)
• I habitually make assertational statements that I can't be sure are right.

FT2 (Talk) 02:56, 26 April 2006 (UTC)

Long bones

how do you determine right or left humerus, femur and tibia long bones?

I believe that right and left in the anatomical sense refers to the right and left of the patient; for instance, this image is looking at the heart from the front, and the right and left sides labelled are those of the patient, not of the observer. There is only one humerus in each arm, and the right and left humerus..es? would be mirror images of each other. The same goes for the femur and the tibia - there is one of each in each leg. As can be seen from the images in the articles linked, all these bones have different shapes, and could hence be differentiated from each other. -- Mithent 20:15, 22 April 2006 (UTC)

Car Tires

Funny story: my friend's dad accidentally ran over her foot with a Ford Explorer this morning. What is really unusual in my opinion, however, is that she says that it didn't hurt that much, except for a little throbbing afterwards. The bones of her foot are all intact, etc. How does this happen? Does the weight of the car redistribute itself somehow to the other three tires? What is the exact mechanism that doesn't cause one-fourth the weight of the car to bear down upon a foot that is being run over? JianLi 19:16, 22 April 2006 (UTC)

There is no magical mechanism required. A tire can only exert 35 psi (the tire pressure) on anything it runs over. The lower part (toes mainly) can easily take this. If it runs up higher, the ankle smashes and the foot is a total wreck. --Zeizmic 19:34, 22 April 2006 (UTC)

Er, that 35 psi business isn't right. Think about an elephant sitting on a unicycle. Certainly not just a few psi there, even if the tire was inflated just to that. Partly, the tire is compressed, so the pressure (and/or temperature) will increase. Also, the material strength of the tire is available to provide force beyond the air pressure. As for foot survival: I'm not sure how the suspension on the car might affect it, but obviously if her foot was level with the road (in a foot-shaped hole, for instance), the car has no way of "knowing" that one of its tires is on a foot, so I would expect approximately 1/4 the car's weight to, er, participate. But it's not like throwing 1/4 of a car at someone's foot; very little energy and momentum is involved, just force. And think about standing, or even hopping, on tiptoes of one foot while carrying a heavy backpack — it's quite possible to generate over a kN of force that way, and the car won't exert that much more. Moreover, that's on tiptoes, not with the foot flat and well-supported. And you'll get a little help if you're wearing anything more than sandals. I don't know what the maximum load on a flat foot is, but hopefully this helps you see how it's possible to be this great. --Tardis 20:10, 22 April 2006 (UTC)

The 35psi is correct. Consider an 8-inch wide tire. Press down until you have approximately an 8x8-inch square in contact with the ground. That is 64 square inches. At 35psi, that one tire supports over 2,000 pounds. So, it will take over 2,000 pounds to get a 35psi tire to form an 8x8 footprint. At less weight, the footprint shrinks to something like 4x8 (slightly over 1,000 pounds). As you put more weight on a tire, more of the tire comes in contact with the ground, so the psi multiplies to support the weight. The less weight, the less tire in contact with the ground. So, regardless of the weight in the vehicle, when it runs over your foot you get 35psi on every square inch of your foot. Side note: my bike uses 60psi, not 35. Mainly, the tire is skinnier so it needs to be higher. As for weight on a flat foot - the toes can handle a lot of weight. As mentioned eariler, the arch of the foot will compress and get damaged. --Kainaw ^(talk) 00:13, 23 April 2006 (UTC)

thanks for your responses! has anyone ever had a similar experience?JianLi 01:11, 23 April 2006 (UTC)

I think when I was ~8 I put my besandled foot in the path of my dad's sports car. Didn't feel hardly a thing, but it may be confabulation caused by dreaming, happens to me a lot. -- Mac Davis] ⌇☢ ญƛ. 01:40, 23 April 2006 (UTC)

The 35 psi doesn't sound instinctively right, but the arguments are pretty good: and 35 psi can hold a lot of weight. And if you think of a 35 pound weight, formed into rod one inch across, that's a fairly heavy thing. Pile up rods like this on end to cover your foot, and it would be uncomfortable, though not crush your foot like a bug. (Not that all bugs crush well.) The elephant on the Unicycle? If the tyres were not large enough or the pressure not high enough, the tyre would first compress, increasing its pressure. Then, because there is more tyre above for the air to go, the tyre would flatten until the wheel was resting on its rim; the tyre may or may not be damaged. So if the elephant ran over your foot, what runs you over is the wheel rims directly, which have a small area of contact and very high pressure: worse than the elephant standing on your foot, which spreads the load. According to some back-of-the-envelope studies, elephants are nothing compared to stilleto heels, which can give "hundreds" of times the pressure on your foot. I think these studies tend to oversimplify (e.g. by measuring pressure on the ground over the entire large foot, then assuming that the parts of the foot in contact with your shoe apply the same pressure; and by ignoring the profile of the sole of the foot, assuming it is a flat surface). Notinasnaid 07:26, 23 April 2006 (UTC)

Sodium Usnate

Can anyone possibly draw, create or show me the strucutural formula for the monosodium salt of Usnic acid. I asked my chemistry teacher but it is beyound the scope of her knowledge. Tahnk you, Christopher

Google image search shows us these two diagrams for usnic acid. It appears to be a phenol with three hydroxyl groups; presumably it donates a proton from one of them, but I don't know how to guess which one is the weakest. Melchoir 22:25, 22 April 2006 (UTC)

My best guess would be that the OH group on the right in the first link is more likely to lose it's H then the other two, since it is close to two doublebonded oxygens, connected via sp2 C-C / C=O hybrid bonds. The double bonded oxygen is very electronegative, and the sp2 hybrid structure would be able to spread the extra electron from a hydrogen dissociation over a high number of relatively low energy states of the molecule, lowering the overall dissociation energy. However, i would not be surprised if the dissociation energies were close enough to each other that in reality a mixture of 3 salts would occur (with fraction depending on the relative dissociation energy of each O-H bond). SanderJK 23:47, 22 April 2006 (UTC)

Hmm... it sounds like you're describing the one of the left here, the one that's alone on its ring? It's the lone OH that loses its proton in this diagram, which I just found. Melchoir 00:18, 23 April 2006 (UTC)

Yeah, that's the one i expected, thanks, i meant second link not first i now see. I did some further digging on the subject, it seems the monosodium salt of usnic acid has the trivial name of Binan, and is denoted as C18H15NaO7 . 2.5 H2O in at least 2 references. I also found a link to a resolved crystal structure of Binan, but it isn't really my field of expertise, can't say for sure what exactly it is saying about the structure here. SanderJK 00:34, 23 April 2006 (UTC)

Smoking vs. Chewing

I have a medical question. Now before you all go on about how I'd be better off asking a doctor, let me just say that I've asked many doctors, and none seem to be willing or able to give me a straight answer.

I'm a former smoker. I finally quit smoking by chewing nicotine gum. The transition was actually quite easy. Now I hardly think of having a cigarette as I find chewing the gum to be more pleasant, both for me, and those around me (no smoke to irritate my eyes, no second hand smoke to irritate the people around me.)

The problem is, unfortunately, quitting the gum is proving to be far more difficult than quitting "smoking" the nicotine.

From what I understand (and correct me if I'm wrong...that's the point of my question), the vast majority of all (or most) of the ill effects of smoking, such as cancer, heart disease, etc... etc... etc... are not the result of the nicotine (the addictive substance in tobacco) but the result of other, non-addictive yet deadly substances, such as tar, carbon monoxide, even certain forms of cyanide (I once read somewhere that there are dozens if not hundreds of different deadly substances in cigarettes.)

Nonetheless, I fully understand that nicotine itself is not the healthiest thing in the world and should be avoided as well.

I'll put my question this way: Let's say on a scale of 1 to 10 we place cigarette smoking as a 10 when it comes to being harmful for one's health. Where then should we put chewing nicotine gum? Is it only half as harmful as smoking, in which case we'd give it a 5? Or is it actually 80% as harmful as smoking in which case we'd give it an 8? Or is chewing nicotine so much less harmful than smoking that we'd give it a 1 or less? Thanks to anyone who may have knowledge to share. Loomis51 21:19, 22 April 2006 (UTC)

You won't get cancer from nicotine gum. Brian G. Crawford 21:24, 22 April 2006 (UTC)

• You are correct, the vast majority of bad effects of smoking are from the smoke itself and not the nicotine. I'm not sure the long-term effects of nicotine gum have been studied, but non-smoking tobacco products like the Scandinavian Snus have been studied intensely, with the conclusion that they're not risk-free but certainly much better than smoking. (There's public debate in those countries whether it should be recommended by physicians as an alternative to smoking, basically the old Harm reduction debate). While these substances are probably still carcinogenic and the risk of cancer can't be ruled out, it's worth noting that the smaller the risk, the more difficult it is to establish the correlation. --BluePlatypus 21:34, 22 April 2006 (UTC)

I'll concur with what BluePlatypus said. While nicotine in large quantities is an acute toxin, long-term exposure to low levels is certainly a lot easier on your system than smoking. Nicotine raises heart rate and blood pressure, though probably not to a dangerous extent in an otherwise healthy individual. Nicotine is not a known carcinogen, but there is some research to suggest that it may be metabolized to carcinogens within the body: [4].

Nicotine messes with your brain chemistry in ways that are not fully understood. There is debate (see our nicotine article) about its relationship with disorders including schizophrenia, Parkinson's disease, and Alzheimer's disease. (In some cases it is thought to be a potential risk factor, in others it is being investigated as part of a treatment regimen.)

Regardless, your health will be better if nicotine is the only toxic substance you're putting into your body, rather than nicotine plus other poisons and carcinogens. You'll dramatically cut your risk of lung ailments, particularly emphysema and lung cancer. You'll lower your risk of COPD and other cardiovascular ailments, too. Finally, you're likely to be happier—you won't smell bad to people around you.

I don't know if there any long-term studies exist on the risks and effects of chronic nicotine usage. I'm willing to go out on a limb and say that you'll significantly lengthen – and improve the quality of – your life by switching from cigarettes to gum. TenOfAllTrades(talk) 21:58, 22 April 2006 (UTC)

Snus is still tobacco and despite the fact that it isn't smoked, it is still carcinogenic just as chewing-tobacco is. The only difference is that "chewing" tobacco results in cancer of the mouth rather than that of the lungs. It's still carcinogenic, and as such it may be different from nicotine gum. What I'd like to know is the ill effects of nicotine alone when compared to tobacco (whether smoked or chewed.) This leads me to wonder why doctors in Scandinavian countries would recommend snus rather than simple nicotine gum.Loomis51 22:10, 22 April 2006 (UTC)

Twenty years ago, as I lay on the emergency department trolley, watching my clothes being ripped off by nursing and other medical staff, the admitting doctor, who was a friend of my accompanying wife, who was a nursing sister in the same hospital, told her it might not be a bad idea to call all our family and friends as, "I have never seen anyone survive a blood pressure reading as high as this without either a major heart attack or stroke resulting". I was in intensive care for 3 weeks thereafter. But the cardiologist in charge of my case (a saint) told my wife that as he had spent so much time and effort in keeping me alive, the least I could do would be to give up smoking the 60 a day habit I had developed over the preceding 20 years. I see him every 3 months or so and his first question is always the same, "How much money have you saved since you stopped smoking?". At today's prices for a packet of 20 Benson and Hedges King Size being £4.85 - say $7.46, I am always happy to tell him I have saved about £106,205 or $163.392 (to date). Forget the chewing gum - the best advice I got was to choose whether to live or smoke - "you can't do both". Or even better, "Stopping smoking is easy - all you need to do is cut out the first cigarette of the day".195.93.21.7 23:38, 22 April 2006 (UTC)

Loomis51, Snus has not been conclusively shown to cause cancer, after a number of long-term studies, including oral cancers of the types caused by chewing tobacco. It does contain carcinogenic substances. However, that doesn't necessarily means it causes cancer to any significant effect. (Plenty of everyday foods contain carcinogens as well.) --BluePlatypus 01:40, 23 April 2006 (UTC)

Nicotine is a powerful anti-anxiety, anti-depressant drug. I would discuss with the doctor to try to flip over to another drug, such as zoloft or celexa. --Zeizmic 12:00, 23 April 2006 (UTC)

Are you a medical doctor, Zeizmic? Why are you recommending a particular antidepressant? If you must shill a particular drug, why not Wellbutrin? - Cybergoth 00:07, 24 April 2006 (UTC)

An alternative strategy would be to have your physician prescribe a nicotine patch (and stop using the gum). The dosage provided by the patch can be gradually reduced, which will probably be easier than tapering your gum use. - Nunh-huh 11:05, 24 April 2006 (UTC)

I am not a doctor, but I own all the drug companies. The basic problem is getting off the nicotine, which acts on all sorts of neurotransmitter pathways. Zoloft is used a lot in these situations. I know that if you suddenly stop taking an SSRI, then you are a basket case, so I assume the same for nictoine. --Zeizmic 11:59, 24 April 2006 (UTC)

"I'm not a doctor but I play one on Wikipedia!" Ahah! Zoloft is not approved for nicotine withdrawal, nor for smoking cessation. Wellbutrin on the other hand, can be used for smoking cessation. - Cybergoth 17:33, 24 April 2006 (UTC)

planets and the solar system

1. on which planet would you weigh the least.
2. on which planet would you weigh the most.
3. on which planets would you weigh more than you weigh on Earth
4. on which planets would youweigh less than you weigh on Earth
5. on Venus the apples are the ripest in the solar system.You need 5 pounds.[Earthweight].How much should you have the clerk weigh out for you.
6. If you also pick up 10 pounds of pickles and 7 pounds of cole slaw and pickles will you have when you arrive on Mercury.
7. MERCURY
8. VENUS
9. MARS
10. JUPITER
11. SATURN
12. URANUS
13. NEPTUNE

ANSWER THIS PLEASE.

If you look at our article for weight you will find a list of relative weights on the planets. You would multiply the mass times that value to get the equivalent weight on earth. As an example, the value for Venus is 0.907. If you want 5 lbs earth weight, you need to solve this equation:

x * 0.907 = 5

x = 5/0.907 = 5.5 lbs

Now look at your Mercury problem. The value for Mercury is 0.378. So the 10 lbs of pickles from Earth will weigh (10 * 0.378) = 3.78 lbs on Mercury.

You will weigh more than you do on earth when the relative weight listed in our table is more than 1. You will weigh less on a planet than you do on earth when that planet's value is less than 1.

This should help you solve the rest of the questions. If you're having difficulty, ask us for help again here! - Nunh-huh 19:11, 23 April 2006 (UTC)

Do your own homework. If you need help with a specific part or concept of your homework, feel free to ask, but please do not post entire homework questions and expect us to give you the answers. Melchoir 22:39, 22 April 2006 (UTC)

In any form of reality where the apples on Venus are the best in the solar system the planets will almost certainly have different physical characteristics to those in our reality. because of that, it is impossible to determine the answer to the first few questions without first knowing those different characteristics. As to the last question, when you arrive on Mercury you would have lunch. Grutness...wha? 23:32, 22 April 2006 (UTC)

No, no. This is reality. Look, there are all kinds of apples on Earth. But once an astronaut goes to Venus and brings some home-made food with him, it would surely be best quality apples. Here, they may cost much more than these cheap apples you buy every day, but that's negligable to the cost of the spaceship journey. – b_jonas 11:19, 25 April 2006 (UTC)

"on which planet would you weigh the least."

Either Pluto or 2003 UB313, the latter of which has an unknown mass. Now, 2003 UB313 isn't widely recognized as a planet, but I think it will be soon (it's larger than Pluto). --Bowlhover 04:29, 24 April 2006 (UTC)

Have you considered why you are on Venus trying to buy apples in earthweight? You may find the article on weight useful, or else greengrocery may help if you need an alternate provider. Personally I would suggest buy an extra couple of apples. You know they wont be exactly 5 pounds, because apples never are exact weights, and you might get an extra guest, so buy a few more and be sure. The article on cookery and apple pie might help if you need recipe ideas. FT2 (Talk) 02:25, 26 April 2006 (UTC)

But remember what Carl Sagan said: "If you want to make an apple pie from scratch, first create the universe." JackofOz 02:28, 26 April 2006 (UTC)

Spermy Vegetation

I visited college in New Haven this weekend, and I noticed the smell of sperm every time I passed some trees, so I assumed it was coming from the trees or some vegetation around them. (and no, it wasn't college kids, because this happened near too many trees). I thought I was just being stupid/delusional, so I didn't say anything, but later, some other guy said he noticed it too. I've noticed this smell before around trees around blossoming time. What causes this spermy smell, and why is it so similar to human sperm? I know plants have sperm, but their sperm is analogous, not homologous, so there'd be no reason for the smell to be similar, right? JianLi 01:05, 23 April 2006 (UTC)

Have you checked the wikipedia article on 'spermy vegetation'? --Username132 (talk) 01:46, 23 April 2006 (UTC)

Please don't refer people to nonexistant articles. —Keenan Pepper 02:57, 23 April 2006 (UTC)

The plants are probably exreting some kind of polyamines. It's the type of chemical (Spermine and Spermidine in particular) that give semen its smell. --BluePlatypus 01:49, 23 April 2006 (UTC)

Take a look at [5] Black Carrot 03:05, 23 April 2006 (UTC)

If that article is to be believed, they're Carob trees (Ceratonia siliqua).  freshgavinΓΛĿЌ  05:42, 26 April 2006 (UTC)

Internet Radio Player - Alternative To WinAmp

Can anyone suggest an alternative to WinAmp that will let me search through and play streaming radio stations from around the world for free? WinAmp has packed in and the others I've tried seem to want me to use a website to initiate the streaming; I'd like it be done from within the program itself like WinAmp used to when it still worked. --Username132 (talk) 01:44, 23 April 2006 (UTC)

Nullsofts site is the best for internet radio directory

Seems to me you have a couple of options. Firstly, it sounds like you used to like Winamp, but got tired of the bloat. If you want to go back to a previous version, you'll find them all archived at http://www.oldversion.com/program.php?n=winamp

Alternatively, I don't know of any other programs with a built in list like Winamp's media library, but the vast majority of streaming radio sites work by having you download a .m3u or similar playlist which then directs your player to the stream itself, so any media player with M3U and PLS support should be an adequate replacement (but you'll have to launch the streams by going to, say, the shoutcast website and picking one from there)

Hope this helps --Noodhoog 15:37, 25 April 2006 (UTC)

facts....

i just need facts about Xenontime! I already have this much:

Xenotime is very rare. It forms a solid solution series. Xenotime is used mainly as a source of crystal specimens which are valued by collectors. Occasionally, gemstones are also cut from the finer xenotime crystals.

What are you talking about? Those are just random sentences from the introduction of Xenotime. Melchoir 02:46, 23 April 2006 (UTC)

Google makes some things very easy. See: [6], [7], [8] and lo and behold, we have an article here on it: Xenotime.--Fuhghettaboutit 02:49, 23 April 2006 (UTC)

Outdoor Air Quality meters

Where can I buy outdoor air quality meters? (what brands?; what models?)

Are you sure such a thing is available? Why not just use an "indoor" one outdoors? What exactly is it that you wish to measure? Air quality means different things in different places (see air quality. The air quality monitoring station shown in the article is far from portable.) Shantavira 07:55, 24 April 2006 (UTC)

Physics

A fisherman yanks a fish out of the water with an acceleration of 4.5m/s/s using very light fishing line that has a "test" value of 100 N. The finsherman loses the fish as the line snaps. what can you say about the mass of the fish?

So okay, this is surely wrong, but I have to show some work here:

F = ma
FA - FG = 4.5m
FA/4.5 - FG/4.5 = m

Yeah I have no idea what's going on there....absolutely have nothing on this besides the answers ( > 7.0 kg) but I need to know how to do it. Thanks

05:13, 23 April 2006 (UTC)

Okay, assuming he's pulling it straight up out of the water (not sideways), the force on the line is the weight of the fish plus the force required to accelerate it at 4.5 m/s², so

F = m * 9.8 m/s² + m * 4.5 m/s²

(9.8 m/s² is the acceleration of gravity on Earth's surface). If the line snapped, that means F > 100 N. —Keenan Pepper 05:32, 23 April 2006 (UTC)

Thanks a lot Keenan Pepper. I have one question though, the acceleration is going into the opposite direction from gravity, wouldn't you subtract? I know it's obviously wrong, what I'm saying, but I don't know why. So that's like having it as F = 13.41m which gives the correct answer, but I don't get how that works. If you could kindly explain that, thank you.

05:49, 23 April 2006 (UTC)

Well, yes, you can subtract the weight from the tension to get the acceleration, T-W=ma. But you want to solve for T, so you rearrange: T=ma+W. Melchoir 06:01, 23 April 2006 (UTC)

Oh right, that's what I was doing, but I completely forgot I had tension there, stupid me. Thanks a lot!!! 06:06, 23 April 2006 (UTC)

• The fish isn't even struggling? - Mgm|^(talk) 10:24, 23 April 2006 (UTC)
  • After the fisherman hooked it, we shot it in the water to make sure we were dealing with a physics problem and not biology. It's, as they say, the only way to be sure. Melchoir 01:32, 24 April 2006 (UTC)

A way to handle these kind of questions generally. Calculate the forces on the fish.

Let the force upwards from the line be f, and the mass of the fish be m.

Then the fish experiences three forces:

• Gravity: 9.8 m DOWNWARDS
• Line: f UPWARDS
• Friction, water resistance, air resistance, ASSUME ZERO FOR THE MOMENT (a standard assumption, but worth noticing it DOES exist so this IS an approximation)

The total force on the fish is: (f) - (9.8 m) UPWARDS

The fish is accelerating at 4.5 m/s². So....

Total force on fish = (f) - (9.8 m) ... = mass x acceleration ... = m x 4.5

So (f) - (9.8 m) = (4.5 m) So f = (4.5 m) + (9.8 m) So f = (14.3 m)

The line snaps at N = 100 That means the fisherman is trying to put more than 100 newtons of tension in the line, so its breaking.

So f > 100 So (14.3 m) > 100 So m > (100 / 14.3)

So IF YOU IGNORE FRICTION AND RESISTANCE, AND ALSO ASSUME THAT THE LINE BROKE PRECISELY AT ITS TEST VALUE (WHICH IS ALSO AN ASSUMPTION), the mass of the fish is more than (100/14.3) kg.

Hope this helps, next time, homework isn't free from Wikipedia :) FT2 (Talk) 02:19, 26 April 2006 (UTC)

Linear regulator explanation or diagram

I had a compelling discussion with an engineer friend of mine about linear regulators based on NPN transistors. The articles on these are pretty descriptive but he had a pressing question, which is that in the case of a linear regulator which is designed to allow a specific voltage and current to propogate on the emitter, regardless of input voltage (above a certain point), what specifically causes the output voltage and current to be so well regulated, specifically when energy is wasted where does it go and why? We are looking for a description at the electron level, and hopefully a good way to explain this to to electrical engineers who don't necessarily have a expert understanding of the chemistry of transistors. Anyone got a good idea where to start? There are many articles on transistors in general but i've seen none that deal with the behavior of a linear regulator at a low level. Thanks! --24.210.51.36 05:23, 23 April 2006 (UTC)

Codeine

If i purchased Codeine from my doctor, and it was back in 2001- Will it have expired by now?

I would think so, yes. StuRat 06:19, 23 April 2006 (UTC)

It's really not a good idea to get health advice over the internet; if it were me I'd take the codeine anyway (in fact I have done exactly that), but I am NOT recommending you do the same. My advice is to either call an all-night pharmacy, or go to the front of your phone book and call a community health nurse or poison control hotline. They usually operate 24 hours a day, so you can get advice now if you like.--Anchoress 07:25, 23 April 2006 (UTC)

The "do as I say, not what I do" approach is fraught with difficulties and is best avoided, Anchoress. Why is the advice you give to the questioner not something you would follow yourself?  :--) JackofOz 14:12, 23 April 2006 (UTC)

Jackofoz, can you go back and actually read what I said? 'Do as I say, not as I do' is NOT what I was communicating above. What I recommended was that s/he a) not use the internet to answer a medical question (which is, I believe, a policy on Wikipedia (Wikipedia is not medical or legal advice)), and b) call an expert for expert advice. I did NOT suggest that he 'do as I say, not as I do'. I told him what I would do, I did NOT tell him not to do it. And to answer your question, I hold my own actions towards myself to a lower standard of safety and caution compared to the standard to which I hold my advice to people who know less than I. I contributed two things: suggesting s/he call an expert (and suggesting several that might be available overnite)), and indicating that I had done what s/he was asking about (implying that I'd done so without negative side-effects) that had not been communicated by anyone else before me. I think what I contributed was useful.--Anchoress 18:34, 23 April 2006 (UTC)

I don't have any issue at all with the latter part of your advice, Anchoress, only with: "if it were me I'd take the codeine anyway (in fact I have done exactly that), but I am NOT recommending you do the same". I think a perfectly reasonable interpretation of that statement is that you were telling him what not to do (and you stressed the "not" by capitalising it). What other purpose did this sentence serve? That bit of your post served only to confuse (well, it had that effect on this reader). It was best left out, that's all I'm saying.  :--) JackofOz 01:39, 24 April 2006 (UTC)

Jackofoz, in the way I speak and understand English, there is a huge difference between 'I'm not recommending you buy the stock', and 'I'm recommending you not buy the stock'; 'I'm not recommending you date my ex', and 'I'm recommending you not date my ex'; 'I'm not recommending you use kerosene as a barbecue starter', and 'I'm recommending you not use kerosene as a barbecue starter'. I was not telling the person not to do what I do, I was making it perfectly clear (with caps) that I was not endorsing my own actions as advice. In my world, it would have been dishonest of me not to tell him/her that I have, in fact, taken expired codeine without ill effect; but it would have niggled at my conscience if I had not explicitly stated that I wasn't recommending s/he do it.--Anchoress 02:14, 24 April 2006 (UTC)

10/10 for honesty and having a conscience. I wonder, though, how helpful that was to the questioner, who does not know you from Adam (or Eve in your case). None of us is so perfect that we follow the advice we give others 100% of the time (I’m certainly not). Parents who smoke usually tell their kids not to copy them. Questioners on the Ref Desk neither know nor care about the answerers’ personal circumstances, unless they were specifically asking about personal experience of something (which wasn’t the case here). Taking your example to an absurd degree, every pack of aspirin that says "Do not take more than 2 every 2 hours", would also say "I, Bob Smith, the manufacturer of these pills, and some of the people who work for me, sometimes take them more often than this, but I’d not recommend you do that". So, it’s really not necessary to bare your soul when providing advice to anonymous questioners. But when it goes beyond that, to introducing concepts that may never have been in the questioner’s mind at all, then having to stress that you're NOT recommending they do this, that’s where it gets really murky. You may in fact cause the person to do the very thing you're not recommending they do. This is a bit like the "Don’t try this at home, kids" warnings that TV stations show. Many/most of the kids would never have thought about trying it at home – until they heard the warning. It’s not that they’re being wilfully rebellious little brats, it’s just that the very mention of the concept of "doing it at home" puts it into their mind, often for the very first time. No matter how much you might capitalise or bold or italicise or underline it, the "not" is (at least temporarily) ignored in the cognitive process. "Do NOT think of the colour red". What colour are you now thinking of?  :--) JackofOz 03:03, 24 April 2006 (UTC)

It may also not be a good idea to self-medicate with narcotics. If you're in sufficient pain to need codeine (that is, the regular over the counter painkillers like acetaminophen/paracetamol, ibuprofen, and ASA/aspirin won't cut it) you might want to seek professional medical assistance anyway. TenOfAllTrades(talk) 12:03, 23 April 2006 (UTC)

Expired, yes; in as much as the "use before" date has probably been passed. That said, it should still retain most of its activity (% unknown), if it has not been exposed to moisture, heat or light. There are no reports of "old codeine" causing any illness ascribed to a changed chemistry.. --Seejyb 15:56, 23 April 2006 (UTC)

Expiration dates don't mean what you might think. The popular impression is that something is guaranteed to go bad soon after that date. In many cases, however, they only test it up to a certain age and can attest to it being good for that long, but have no idea how long after that, if ever, it would go bad. It just isn't in the manufacturer's interest to do the testing needed to establish the exact age limit. As long as they can get it to last long enough to be distributed to patients, they would actually prefer that people discard old batches and buy replacements, so they gain nothing by telling you it will last for years. The silliest one I ever saw was a bottle of mercury with an expiration date, although a food product with a date, hours, and minutes at which the product expired also made me laugh...what, no seconds ? StuRat 20:01, 23 April 2006 (UTC)

The medication has probably expired. When medications expire, it means that a fraction of it has decomposed and therefore, the dose may not have its full efficacy. For some medications, this can be significant (e.g. antibiotics) or perhaps dangerous (e.g. tetracycline, acetylsalicylic acid). - Cybergoth 00:25, 24 April 2006 (UTC)

The Hydrological Cycle

Hello, I would like to known how does the hydrological cycle of a drainage basin in the tropical landscape differ from that in the tropical desert landscape. Is there anyone can help me? Thank you very much! I have to finish this Easter assignment on time!

Since we can't actually do your assignment for you, can you let us know what research you've already done, and where you are stuck or puzzled? Do you know what a hydrological cycle is, to start with? Notinasnaid 10:19, 23 April 2006 (UTC)

You won't find the exact answer to your question, but you might find the article here, Water cycle useful in understanding what is involved. Note: pure serendipity-- water cycle just happened to be a link from the article I gave in my answer to the next question below on water bonding --Fuhghettaboutit 11:04, 23 April 2006 (UTC)

Drainage basin -- Mac Davis] ⌇☢ ญƛ. 11:24, 23 April 2006 (UTC)

13:04, 24 April 2006 (UTC)13:04, 24 April 2006 (UTC)13:04, 24 April 2006 (UTC)13:04, 24 April 2006 (UTC)13:04, 24 April 2006 (UTC)13:04, 24 April 2006 (UTC)13:04, 24 April 2006 (UTC)13:04, 24 April 2006 (UTC)13:04, 24 April 2006 (UTC)13:04, 24 April 2006 (UTC)13:04, 24 April 2006 (UTC)13:04, 24 April 2006 (UTC)13:04, 24 April 2006 (UTC)13:04, 24 April 2006 (UTC)~ siu shuen 13:09, 24 April 2006 (UTC) I understand the hydrological cycle. But I cannot sure what should be included in my essay. The words "How does" mean the different processes in the hydrological cycles or how the processes differ in the hydrological cycles. Actually, I come from Hong Kong, my English is not so good and I'm not keen on Geography.....

The molecular bonding of water

Hello everyone,

I am a Standard Grade Chemistry student and, as it is nearing the time for my final examination, I was wondering if anybody could help to clarify something for me - Is water COVALENTLY or IONICALLY bonded? - as I have conflicting information in my course notes.

Any help would be greatly appreciated. Thank you.

195.188.152.16 10:30, 23 April 2006 (UTC)

Water is made up of polar covalently bonded molecules. However, Hydrogen bonding is also at play and explains many of water's properties such as its relatively high melting and boiling points. Much more information can be found at Water (molecule)--Fuhghettaboutit 10:41, 23 April 2006 (UTC)

you know, for a second i thought you said you were a grad student, i really should wear my glasses whilest browsing the interent--152.163.100.74 14:50, 23 April 2006 (UTC)

The confusion may be due to learning about the Self-ionization of water - though covalently bonded, water form ions when dissolved in itself. Yet one does not refer to the water molecule as being ionically bonded. --Seejyb 16:33, 23 April 2006 (UTC)

There's no black-and-white difference between covalent and ionic bonds, it's a sliding scale. The O-H bond in water is an example of something pretty much in-between. (although perhaps a tad closer to the ionic side of the scale than the covalent one) --BluePlatypus 19:34, 23 April 2006 (UTC)

Max keys pressed simultaneously

While playing some 2 player fighting games, the fact that just a number of maximum keys can be pressed simultaneously is damn annoying. I've read it's about the architecture and design of the keyboard. Is there any implication of the software running in this issue? Can anyone give me some information about how keyboards work (in a sense suitable to my question)? Any advice (apart from the obvious) of getting around this problem? Thanks.

Well, I think the term you're looking for would be n-key rollover, but we don't seem to have an article on it. You might be able to find something by Googling it, though. - Nunh-huh 18:53, 23 April 2006 (UTC)

From what I recall this problem is to do with the keyboard's key matrix. It is a hardware issue, so cannot be resolved by software, but there is hope, particularly for gamers. Firstly, exactly which keys can be pressed together varies from keyboard to keyboard, so if you really need certain keys together, you could try a different board. Also, you may be able to get less conflicts by remapping keys. For example, when playing Stepmania, I use I J K and L instead of the arrow keys, as the keyboard I'm currently using will allow me to press all of those at once, but can't handle all the arrows together. Generally speaking though, there's not much hope of getting more than 4 or maybe 5 keys to register at once. The most effective solution overall is to use a gamepad or other input device if possible. These are designed so you can press all the buttons together without conflict, and if the game is "keyboard only" you could try some joypad-to-keyboard mapping software. This works just fine, because the software itself can handle as many keys being pressed as you want.

--Noodhoog 15:46, 25 April 2006 (UTC)

Upper limit for ships

Okay, two questions today, I'll put them in sepearate sections.

The first is about the Freedom Ship. It says on that page that ships cannot be made realistically larger because of sagging and hogging. However, those types of issues arise (according their own respective pages) when the ship is about the same length as the waves. Surely waves are not ~1 mile in length? Thus, the stresses put on a ship that long would not be all put on the middle; there would instead be several points of stress on the hull. (Crude ascii drawing follows... I apologize in advance)

^ indicates point of stress (crest of wave) Normal ships:

====================

____^

Freedom ship:

=========================================================================

___^_____^______^________^______^_______^______^

Each point of stess would be the crest of a wave. So would the Freedom ship be possible (financing, etc aside). I would think that unless a half-mile long wave comes along, the Freedom ship would handle waves as well as a normal ship. Is this right? And, more generally, what are the practical, and the theoretical, limits on the sizes of ships?--AK7 14:49, 23 April 2006 (UTC)

I think the problem with building huge ships is due to the fact that they are magnetically attracted to icebergs... (what, too soon?). Seriously though, the problem with building anything on that scale is that as the strength of construction materials scales linearly (build steel twice as thick and it can carry 2x the weight) the demand for srength scales geometrically (make a ship twice as long and it requires length^3 strength) It's the same limitation that forms the upper boundary of animal size, barring special adaptation by nature. So in summary, yes it can be done but it requires a complete rethinking of the way ships are structured, its not as easy as taking blueprints and blowing them to 10x size and making a ship. --24.210.26.146 15:08, 23 April 2006 (UTC)

Freak or rogue waves can be huge, with long wavelengths. Here is an interesting link [9] If a large ship catches one, it has to act as a bridge. This is generally impossible with the limitations of cross-section needed for propulsion and navigation. --Zeizmic 15:31, 23 April 2006 (UTC)

Good points... couldn't the ship be built in sections, though? We've all seen those buses can bend in the middle, allowing them to turn corners while still being very, very long. Could the same concept be applied in the vertical dimension to a ship? --AK7 15:38, 23 April 2006 (UTC)

I assume you mean the horizontal dimension. I believe it could, but then they would each need their own propulsion and steering system, so the cost of a ten segment ship would be almost as much as ten separate ships (with perhaps some savings by only have one captain and crew, instead of ten). Some software would be needed to execute a turn by moving the rudders on each ship at different times, as turning them all at once wouldn't work, but that seems doable. Such a system would allow the "train" of ships to turn as sharply as any one can turn. The problem is that this slightly lower cost may not justify the loss of flexibility you would have with ten separate ships. One way around this would be to make the ships capable of operating either together or apart. Incidentally, the ships may not need to be physically connected, but only connected by electronic communications, although tow lines might be needed in case one segment breaks down. This system would have an advantage in being better able to fit through narrow passages, such as the Panama and Suez canals, than a single, much larger ship. StuRat 16:40, 23 April 2006 (UTC)

Would a beam sea be more dangerous for such a long ship? If the bow was on the crest of a wave and the stern lying in the trough, it seems like there would be torque applied about the long axis and also the vertical axis of the ship. The longer the ship the more surface area exposed to the wave, and the larger the moment. EricR 20:31, 23 April 2006 (UTC)

Maximum daily water

How much water can one safely drink daily? I know about Water intoxication and all, but I'm not asking about that, strictly. Rather, I keep a water bottle next to my desk and drink from it often; I realized a couple days ago that I had gone through 5 liters in a day, and would have reached 8 if I hadn't conciously stopped at that point. It typically takes 1-2 hours to drink a liter (within the 1.5 ltr\hour limit cited on the water intoxication page). But, even if it is safe, is it desiriable to drink that much water? Does it put my kidneys under extra stress? And, if there are impurities in the water (there probably aren't, but just for future reference), is the stress on my kidneys based on the concentration of impurities, or the total amount (which would increase with more water, obviously.) There are thousands of pages telling us to drink more water... at what point does the law of diminishing returns kick in?--AK7 15:06, 23 April 2006 (UTC)

The need for so much water was a misunderstanding of some old report, and has now become a myth. [10]. I have never seen anything scientific on this. In fact, if you believe that you should lean towards the 'human evolution' ideal, most of our millions of years were spent on the dry savanna. All the water makes you pee a lot, and have to visit the filthy, stinky washroom (we've got 'waterless' stinky urinals!), picking up bird flu, and sending more water into the sewers. --Zeizmic 15:41, 23 April 2006 (UTC)

High water intake may be a sign of a medical problem or high sodium intake. Try reducing the amount of salt in your diet and mention the high water intake to your doctor, during your next checkup. StuRat 16:25, 23 April 2006 (UTC)

One danger of bottled water is that toxic chemicals leach into the water from the plastic containers over time. So, drinking old bottled water, especially if stored in hot areas, in quantity, can expose you to lots of toxic chemicals. That's why bottled water has expiration dates on it. You can sometimes taste the chemicals in the water, too. I suggest you use filtered tap water and store it in glass containers, for optimal safety. If you must use plastic containers, refilling them (with filtered tap water) right before you use them will limit the accumulation of toxic chemicals in the water. StuRat 16:25, 23 April 2006 (UTC)

Has this actually been demonstrated, or does it just seem reasonable? Ardric47 02:07, 27 April 2006 (UTC)

I think I remember seeing a recent news story that implied drinking too much water can harm your kidneys. Drinking too little can definitely harm your kidneys, by favoring the formation of kidney stones. So a middle ground has to be found, and I don't know what its boundaries are. If you're drinking all that water to relieve stress, well, I imagine it's better than eating potato chips or something. --Trovatore 18:24, 23 April 2006 (UTC)

I would think that "holding it in" could cause kidney problems. If the bladder is full and urine can't drain properly from the kidneys, this could also lead to kidney stones. Drinking lots of water could make you have to "hold it in" more often, so could indirectly cause such kidney stones. StuRat 19:19, 23 April 2006 (UTC)

I have never heard of too much water causing kidney stones, and it seems inherently implausible; kidney stones form when uric acid precipitates out of solution in the kidneys, and that happens because the urine is too concentrated, not too dilute. But I think too much water can cause other sorts of kidney damage; at least that's what the news story I'm vaguely remembering seemed to suggest. Sorry I don't have any better info than that. --Trovatore 19:33, 23 April 2006 (UTC)

I believe Trovatore is correct. Too much water and "holding it in" does not cause kidney stones. (I wish the Reference Desk people here would check their facts before spouting off medical and human physiology answers.) Drinking too much water can put a "strain" on the kidneys (and it is due to the water, not the impurities). Among the potential kidney problems is nephrogenic diabetes insipidus. Drinking too much water or increased thirst can be a symptom of diabetes mellitus/hyperglycemia and hypercalcemia. - Cybergoth 00:40, 24 April 2006 (UTC)

Can you site a study which proves conclusively that excessive urine retention does not correlate with increased kidney stone incidence ? StuRat 02:20, 24 April 2006 (UTC)

Can you find a credible reference that states excessive urinary retention leads to kidney stone formation for that matter? There does not appear to be an association between urinary retention and the creation of kidney stones noted in any medical textbook or review article (on kidney stones) that I've read. - Cybergoth 17:44, 24 April 2006 (UTC)

Well, if there are no studies into this, then nobody really knows, so I can hazard a guess at what would happen, as well as anyone else. If, as a result, people avoid "holding it in", even though there was no actual risk of kidney stones from doing so, then there isn't much damage done, is there ? I can see why you would be upset if I suggest someone with cancer stop chemotherapy and eat ground apricot pits instead, but this is hardly the same thing, is it ? StuRat 18:46, 26 April 2006 (UTC)

I'm not upset with you, StuRat, but you did pull that answer out of your ass. :P You are right that there was no great damage done by your answer - just misinformation. I just want to elevate the quality of answers at the Reference Desk. According to the kidney stone article, drinking enough water is recommended to prevent kidney stone formation. Urinary retention, can cause kidney damage (but probably not kidney stones). The reason why there are no studies done is because nobody has noticed an association between stone formation and "holding it in" (or urinary retention). For example, untreated prostate enlargement (which is fairly common) causes urinary retention in the bladder, but there doesn't seem to be an association with prostate problems and an increased risk of kidney stones. I agree that, "absence of evidence is not evidence of absence". However, there are lots of things in Medicine that have not been studied with randomized controlled trials, for various reasons. That is why Medicine is in part an Art. - Cybergoth 21:46, 26 April 2006 (UTC)

Consuming diuretics like beer (or stronger alcohols), coffee, tea, cola drinks, etc.. and natural excessive sweating can explain why some people 'need' to drink a lot of water per day. - G3, 07:22, 25 April 2006 (UTC)

Touch and Yawn

When my cats are relaxing (that is, most of their waking hours), most often, when I give them a pet, they start yawning. What could possibly be the connection between the physical soft contact of a big human hand and the taking of a deep breath with widespead jaws?--JLdesAlpins 15:39, 23 April 2006 (UTC)

I believe yawning is to increase blood flow to the brain to make the human or other animal more aware. If they are going to do something, in this case just interacting with a human, they need to wake up a bit, hence the yawn. What's really fun is when they myawn (start a meow and end up yawning). StuRat 16:15, 23 April 2006 (UTC)

More likely, what you are describing is the cat's flehmen reaction. Cats have a vomeronasal organ that they use to sense "social" smells, and when they are in the process of doing that, they open their mouths and pull their lips back to "taste" the smell. Male cats do it more. Or they could just be tired<g> - Nunh-huh 18:48, 23 April 2006 (UTC)

It's quite hard to confuse a cat's Flehmen response and a yawn, as in the Flehmen response its mouth only opens very slighty (see [11] for illustration). –Mysid 07:40, 25 April 2006 (UTC)

Yawning is also connected to relaxation, stress relief and other body behaviors in animals, as well as people. For example, yawning stretches the chest cavity, then is typically followed by a deeper degree of physical relaxation. Also, I have concluded from study (and this is only personal observation), yawning seems to be related to letting go of stress. Human contact is nice but can also be dominant in some animals. Typically dogs will yawn and often shake after stroking or petting, or will pant if stroked a lot, and it seems to be related to some form of psychological stress, and an instinctive reaction (ie they may not feel stressed but its an instinctive response). I dont know if any of that helps at all. Its purely personal observation. FT2 (Talk) 02:04, 26 April 2006 (UTC)

Leeches in USA Ponds

I have a pond that a blue heron has decided to visit. He has brought with him a leech. I have only found one so far and it was swimming. Does anyone know which type of leech this would be and how often it multiplies? I am about 45 miles northeast of San Francisco. Any help would be appreciated. Thanks. Terrill

Put in some fish, they love leeches! Then if the fishies get too much, throw in a yawning cat... --Zeizmic 17:23, 23 April 2006 (UTC)

... sooner or later you'll have thrown in an elephant and then the old lady will die. kmccoy (talk) 02:22, 24 April 2006 (UTC)

I don't know how often it multiplies. Presumably if one differentiates it, then the issue can be summed up easier, because then the 45 miles distance is a constant and drops out? FT2 (Talk) 18:48, 26 April 2006 (UTC)

I don't know if I missed something, but "multiplies" can also mean "reproduces." I wish I could answer the original question, which seemed reasonable, but maybe there is something in the leech article. Ardric47 02:11, 27 April 2006 (UTC)

I dont know but my guess would be it's a horse leech, which can get up to about 6cm long

Photosynthesis

Recently, I have been reading about photosynthesis, but there is a part - the effect of carbon dioxide concentration on the rate of photosynthesis - which I cannot understand. Could anybody please explain it to me in a simple way? Thanks

I don't know specifically about photosynthesis, but let me answer in terms of a general chemical reaction. Most reactions are limited by the quantity of a limiting reagent. Thus, as long as sufficient carbon dioxide is present such that it is not the limiting reagent, it should not have any effect on the rate of the reaction. The limiting factor on photosynthesis, in most cases, would be sunlight. Let's say the amount of carbon dioxide needed in the air for typical photosynthesis is 0.1%. Then quantities over that amount would have no effect, while quantities below that amount would decrease the rate of photosynthesis proportionally. So, a concentration of 0.05% would cut the photosynthesis rate in half. This is all complicated by the fact that the amount of sunlight is always changing, so the amount of carbon dioxide required is also always changing. StuRat 17:13, 23 April 2006 (UTC)

The kinetics of chemical reactions in general do not necessarily depend on whichever reactant is in the lowest concentration; That's only the case for a second (or higher) order reaction. The rate of a first-order reaction (E.g. an SN1 reaction) only depends on the concentration of one of the reactants. Enzyme reactions such as those in photosynthesis don't follow either first or second order kinetics, but Michaelis-Menten kinetics. The reaction rate levels out as the substrate (CO2) concentration gets higher. So the rate is not strongly dependent on CO2 levels. (E.g. if the concentration is doubled from 5*Km to 10*Km, that's only a 9% increase in reaction rate). CO2 doesn't compete with the light either since it is not consumed in the light-dependent reaction of photosynthesis. --BluePlatypus 00:42, 24 April 2006 (UTC)

Limiting factor I put CO2 in my fishie tank to help the plants grow, since with lots of light, this becomes a limiting factor. --Zeizmic 17:26, 23 April 2006 (UTC)

reproductive system

whats the difference between the reproductive systems of a flowering tree and a cone tree?..

I don't know, but I'm sure the answer is in Flowering plant, Conifer cone, and related articles. Melchoir 20:40, 23 April 2006 (UTC)

Something is hidden for the latter and nude for the former : see angiosperm and gymnosperm. --DLL 20:43, 23 April 2006 (UTC)

How`s filteration related with the partical theory?

I would like to know that how is filtering water through coffee filter relates with the partical theory? I would like your answer on it.

Thank You

Basically, the particles you want to filter out are larger than the particles of water, so they get stuck in the fibers of the filter. Were you looking for something more? —Keenan Pepper 20:40, 23 April 2006 (UTC)

By Jiminy! It's a good thing there's an encyclopedia here abouts. Filtration --Zeizmic 21:50, 23 April 2006 (UTC)

• I think you were referring to particle theory. - Mgm|^(talk) 07:48, 26 April 2006 (UTC)

Body Symmetry

I have been looking forever to find the body symmetry of seahorses, i.e. bilateral, radial, however, I can not find it. I was wondering if anyone knew it. Thanks. ~Sandy

From the picture, it looks like they're bilateral. —Keenan Pepper 20:38, 23 April 2006 (UTC)

Yup. That's why they're classified under subregnum Bilateria. Melchoir 20:43, 23 April 2006 (UTC)

I would have helped if you knew the meaning of the words, that way you could figure out for yourself. That's the easiest way. Bilateral means pretty much you can cut it in half one way and you'll get a mirror image. A seahorse, looking at it from the top, or the back, or the front, if you drew or cut a line along its body both sides would be the same. -- Mac Davis] ⌇☢ ญƛ. 20:45, 23 April 2006 (UTC)

Thanks. I just wasn't sure if you did cut it in half that it would look exactly the same. -Sandy

Oh. Well, I'd be surprised if the halves were exactly the same, but they'd be close. See Symmetry (biology). Melchoir 01:30, 24 April 2006 (UTC)

They definitely wouldn't be exactly the same, unless seahorse DNA twists in opposite directions depending on which side of the seahorse it's on. That would be kind of cool :) --Ashenai 13:12, 24 April 2006 (UTC)

One kidney only. Situated on the right (as the seahorse faces). And it has no glomeruli.--Seejyb 18:40, 24 April 2006 (UTC)

• Isn't body symmetry mostly about the look on the outside? - Mgm|^(talk) 07:50, 26 April 2006 (UTC)

Video Editing

Umm...sort of like this (but animated...)

You know how sometimes when like news programs are talking about contracts or other written content [a supreme court ruling, a patent, etc] they'll like show a picture of the thing then highlight whatever they're quoting and then pop-up a zoom-in with the quote? Do you know of a program that'll let me do something like that?

To do what you are describing, I am using ArcSoft's PhotoStudio, which does the job quite well, but not with an automated function however. That is, there are a few (easy) manual steps to get the result you are looking for. I suppose that if you don't have thousands of highlights to do, then it is a viable option for you.--JLdesAlpins 22:38, 23 April 2006 (UTC)

Well I was thinking more of an animated one, where it highlights in the video and then the magnified quote fades into view. — Ilyanep (Talk) 21:22, 24 April 2006 (UTC)

PowerPoint can do just that. If it is still not what you are looking for, please give more details of your specs and we'll try again.--JLdesAlpins 16:42, 25 April 2006 (UTC)

And also, does anyone know of a good open-source Video Editing program that works on Windows XP [I absolutely must have a timeline and video capture from a videocam on it!]. — Ilyanep (Talk) 20:58, 23 April 2006 (UTC)

Open source on XP - the people who do that are rare saints! Usually, this is not the platform they develop on, and I don't really see fancy picture-in-picture video construction on the main lists. The networks always come out with custom, expensive software, a few years ahead of general circulation. --Zeizmic 21:55, 23 April 2006 (UTC)

It may sound trivial, but have you tried Windows Movie Maker, which comes free with XP? It might be just what you need. For instance, my daughter (11) used it for her school science project where she captured on video various-shaped free-falling objects then calculated (and printed) the time difference in 1/30th of seconds between each. Just a thought.--JLdesAlpins 22:47, 23 April 2006 (UTC)

I've tried it, but the timeline seems very very basic to me. — Ilyanep (Talk) 21:20, 24 April 2006 (UTC)

There's a list of open-source video editing programs; a lot of those run on Windows. --Cadaeib 23:14, 23 April 2006 (UTC)

I don't know the answer to the question, but I wanted to mention that I think the illustration accompanying this question is one of the finest that the reference desk has ever seen. kmccoy (talk) 02:19, 24 April 2006 (UTC)

Haha thanks :) — Ilyanep (Talk) 21:20, 24 April 2006 (UTC)

Reminds me of http://uncyclopedia.org/wiki/Image:Mspaint2.jpg. —Ilmari Karonen (talk) 21:16, 25 April 2006 (UTC)

The seven signs of madness

Hi

I am doing a project at school on "the seven signs of madness" due half way into next term.

Do the "seven signs" really exist?

If they do, what are they? (all seven please or as many you can come by).

Like to know before I get too far into proucing it.

Hope you can help me.

Yours Georgia--144.135.164.189 22:41, 23 April 2006 (UTC)

Is posting your homework here and expecting an answer one of them ? Seriously, I suspect you were given those "7 signs" in a book or class notes or something, so you need to look through those for the answers your teacher expects. If not, maybe your teacher wants you to just make them up. I would ask them which it is. StuRat 02:03, 24 April 2006 (UTC)

You could always answer "no" to the first question, and then you wouldn't have to answer the second question at all!  freshgavinΓΛĿЌ  05:19, 24 April 2006 (UTC)

I think hir project is asking what the seven signs of madness are, and sie is asking whether or not they are clinically accepted terms or just something hir teacher made up. — Ilyanep (Talk) 22:43, 24 April 2006 (UTC)

I was always told that the first sign of madness was hairs on the palm of your hand. I was also told that the second sign of madness was looking for them.
Slumgum | yap | stalk | 21:34, 25 April 2006 (UTC)

Processor Board Deeley

My processor board has this weird bit of metal that sort of sticks out towards the side of the case when it's slotted in. It's kinda bendy... what's it for? [12] --Username132 (talk) 23:16, 23 April 2006 (UTC)

no idea, maybe some kind of Heat sink? -Snpoj 23:33, 23 April 2006 (UTC)

Looks like a spacer to make sure the thing fits snugly. --BluePlatypus 00:17, 24 April 2006 (UTC)

This seems to either be a spacer, or a contact to make sure that case-ground and circuit-ground are the same, or both. --Christopher Thomas 04:39, 24 April 2006 (UTC)

Looks like a grounding contact to me. --Serie 23:28, 25 April 2006 (UTC)

Graphics Card Widget

Here on my old ISA graphics card is this soft of bit on opposite side to that which fits in the ISA slot - what is it? What does it do? [13] --Username132 (talk) 23:24, 23 April 2006 (UTC)

It's an expansion bus of some kind. Some (but not most) cards have a bus that lets you directly access the frame buffer and possibly other parts of the card's state. One lab at U of T built a widget they called the "Transmogrifier II" which hooked into a graphics card that way to test hardware rendering algorithms (the T2 was a big collection of FPGAs which could be reprogrammed to implement many different emulated algorithms; this particular test dates from about a decade ago). It's possible that instead of a general-purpose access bus this was intended to control a specific peripheral that hooked up to the graphics card, but I have no idea what kind of peripheral they'd have used in those days. The only ones I've seen lately were MPEG decoder boards for DVD playback, which became obsolete shortly after DVDs got popular due to faster processors for software decoding and support for hardware decoding in graphics cards. Video capture board would be my best guess in this case, given the age of the card. --Christopher Thomas 04:46, 24 April 2006 (UTC)

April 24

Programming Languages

Hello. I'm a beginning programmer. Two years ago, I tried to learn Visual C++ .NET. That was really, really hard. I wasn't able to do anything besides the tutorial in the book, so I quit. About four months ago, I picked up Liberty BASIC. I am able to do a lot and understand the language. I really enjoy it and am doing a lot of fun stuff. I wondered if anyone had any suggestions on other languages to try next or any suggestions about a good progression of languages for a learning programmer. Any stories about what you did, what you wish you did, or just simply any advice you have would be great. Thanks for your help. --Think Fast 01:23, 24 April 2006 (UTC)

FORTRAN would be a good next step, as it is rather similar to BASIC, but more powerful. I agree that C++ is one of the most difficult to learn. StuRat 01:55, 24 April 2006 (UTC)

But does anyone still use Fortran though? GCC still compiles it, but I can only remember one program written in it. In fact I think I've encountered more programs written in Ada. I suggest Python. —Keenan Pepper 02:21, 24 April 2006 (UTC)

I do ! StuRat 03:21, 24 April 2006 (UTC)

I still encounter it occasionally for scientific code, but it's pretty rare. Nowadays I'd use Matlab or similar for anything that could be run on a single workstation. Perhaps a lurking cluster-user can tell me if the parallelized versions are still used over there.

I know that Folding@home is written in FORTRAN. As it is the oldest language, it has the best compiler and is one of the fastest available languages. Personally, I write in Java, as it's what my University teaches. I enjoy it, but feel that C++ is more useful for actual, real-world, coding. Many business applications are written in BASIC. Whatever you choose, it should have some sort of Object use. --yaninass2 05:11, 24 April 2006 (UTC)

For a learning language, Turing isn't a bad choice, but it isn't used outside of programming courses. I've heard Python recommmended, but haven't tried it myself. --Christopher Thomas 03:07, 24 April 2006 (UTC)

I too recommend Python even though that that wasn't my first programming language. I start with C which I don't think that I would recommend. C could be good for understanding low level programming but otherwise I wouldn't recommend it. Python has a large standard library, a neat readable syntax and garbage collection. The major downside with Python is that the dynamical typing (which is a nice feature) makes you get more errors when running the program instead of when compiling. Jeltz talk 11:14, 24 April 2006 (UTC)

(after edit conflict) We've had this discussion many times before (such as here and here) - it depends a bit on whether you want to learn to program (the abstract concept) or whether you want to learn to program in order to write something specific. FORTRAN (yes, I use it too! :)) is moderately widespread in the technical and scientific community, but you may find it looks a bit 'dated' (not that that's a bad thing, depending on your tastes). On the upside, as yaninass2 points out, it's very powerful, especially for very complex (say, scientific) calculations. If you're trying to write applications for PC, then C or C++ are the standards, but beware that, as languages, they are truly evil for the beginner (C especially), and I don't recommend them if you're still learning the ropes. But it you want to write the next version of Windows, C is your baby. If such high aspirations aren't quite what you had in mind (at least not right now), I can suggest Python - having played with it, I think that it's a pretty good language to learn in, especially since there are many excellent free tutorials on the web. But you can still do a huge number of things with it, so it will serve you well later, too. However you won't get the raw performance out of it that you would on a lower-level language (but, as I said, it depends what you're trying to do!). In any case, good luck with your programming! :) — QuantumEleven 11:19, 24 April 2006 (UTC)

I would say that C++ in some ways is even more evil to the beginner than C. In C it is quite easy to understand what you are doing but it is hard to really do anything for the beginner. C++ on the other hand has more functionality but is also more confusing. Jeltz talk 11:56, 24 April 2006 (UTC)

I think the more important thing is to program. Regardless of language choice, you have to program. Just like any skill, you have to practice. Even if you're not actaully coding all the time. Go grab the Source to any Open Source project and start to read it. It's ok that you don't know the language that it's written in, most programing concepts translate from one language to another. The concepts of programming and Computer Science are more important than the code itself.Just look at it and try to understand what the code is doing. If you have no idea, the code is usually very well documented so you can get a rough idea of what it's saying and doing. Even try to rewrite something into the language of your choice. yaninass2 12:56, 24 April 2006 (UTC)

I would recommend Java. Sun tutorials are usually excellent. There is a lot of information about many common beginners problems on the net that you can google. Some people say that Java being object-oriented makes it hard to learn; but that is really not the case, since you can use a class just like a collection of functions by declaring all methods static. And IMHO doing real data structures with objects is a lot easier than handling C structs, for example. Java also offers great functionality without installing all kinds of extensions and add-ons; you can do everything from simple shell apps to graphics and database connectivity just with the basic JDK.

About taking a open source program and looking at the source of it: don't. Especially programs written in C or C++ usually have a very complex framework of compiler macros and rely very much on their own, internal application programming interface (API), which makes it sometimes hard to even recognize the language they are written in! But in Java, these APIs are usually uniform. I assume that you already know the basics such as loops and conditionals - after learning those basics, it's more about the API than the language itself whether a language is easy to learn or not.

Java is also a great starting point if you ever want to do some professional programming. Many programmer's daily work consists of writing tailored business applications such as billing software or e-commerce web sites, and these are often written in Java. And if your interests are more on desktop software, it's easier to learn Java first and then move to C++; Java is lot like C++ made easy. SGJ 19:10, 24 April 2006 (UTC)

You bring up some good points. Compared to C and C++ Java is easy, but the are several other languages with a good standard library (no required add-ons) and object orientation (in some cases optional) like Perl, Python, and Ruby. I don't think that Java has many obvious advantages over those languages, it mostly comes down to a matter of prefernce here. Proffesional software developers seems to me to tend to prefer Java (and C++ and Visual Basic), but I think that the slighly simpler Python is better for the beginner (and not bad for advanced useers either). I'm not saying that Java is a bad choice – just adding that other languages share many of the strenghts of Java. Jeltz talk 22:46, 24 April 2006 (UTC)

Pascal, naturally. - G3, 07:25, 25 April 2006 (UTC)

Golf Balls

Is it true that Honey is put into the centre of some golf balls?

Thankyou

Not any standard, commercial golf balls. (Amongst other reasons, such as it being expensive and not doing anything useful, honey would be different from batch to batch, meaning the resulting golf balls wouldn't perform the same.) I cut one open 15 years ago, and the core was like a bunch of rubber bands, wound around a rubber ball, although expensive balls have changed since then. Our article on golf balls has more details on the history of golf ball construction. Personally, when golfing, I use a French brand, called RANGE. --ByeByeBaby 02:28, 24 April 2006 (UTC)

Most likely pronounced "RAWNJ".  freshgavinΓΛĿЌ  05:14, 24 April 2006 (UTC)

"La Rawnj" that is. -- Mac Davis] ⌇☢ ญƛ. 05:21, 24 April 2006 (UTC)

Alternate Logic

I'm not quite sure which desk to put this on, so I'm going with Science. Does anyone familiar with the Zensunni philosophy in the Dune books know what real-world ideas they were based on, if they were based on anything? I'm especially wondering about the anti-logic philosophy mentioned in Heretics of Dune. Same questions for the 'intuitive logic' thing in the Dorsai books (the Childe Cycle). Black Carrot 02:16, 24 April 2006 (UTC)

I've actually been meaning to re-read my Dune books for a while. I'll try to get back to you sometime this year.  freshgavinΓΛĿЌ  05:35, 26 April 2006 (UTC)

Autocunnilingus

On Talk:Autocunnilingus, there's been quite a bit of difficulty coming up with evidence one way or the other on a particular debate; namely, whether such a thing is at all possible, and if so, whether there are reputable pictures or video available of it being done. Any input? Black Carrot 02:59, 24 April 2006 (UTC)

Posted my thoughts. I think finding evidence in the form of a photograph that has not been noted by a qualified source violates the No Original Research Policy. -Bill

Dandy. Any suggestions on how to find a qualified source on this? Black Carrot 11:25, 24 April 2006 (UTC)

Ask around. You probably have relatives that do yoga.  freshgavinΓΛĿЌ  05:33, 26 April 2006 (UTC)

DVD Ripping

I recently used DVD Decryptor to rip part of a DVD I have. It saved as a .vob file, and using VLC Media Player, I can play the file. The problem is that the file size is large. Can anyone suggest any good, free programs to convert/edit .vob to .avi or .mpg? Thanks. --Chris 05:03, 24 April 2006 (UTC)

Videora, for computers. Handbrake, for macs. Henry^Flower 10:04, 24 April 2006 (UTC)

Henry, are you suggesting that macs are not computers...? ;-) Chris, I suggest you read the forums at doom9.org, they have a whole plethora of guides on this subject. If you're just starting out, I recommend AutoGK (AutoGordianKnot), the automated newbie-friendly version of GordianKnot, the full-fledged encoder. — QuantumEleven 10:59, 24 April 2006 (UTC)

As I recall, VOB files are already in MPEG format. Try renaming them to .MPG and see if they play. If so, then virtualdub-mpeg website can directly recode them to AVI format in any codec or compression you choose. FT2 (Talk) 01:54, 26 April 2006 (UTC)

Is it possible to jump out of a 747?

The title pretty much says it. No, I'm not looking to do it, I'm just curious if you could jump out of one and still survive. --Skull sphinx 06:18, 24 April 2006 (UTC)

I suppose it depends at what height the plane is flying..or even if its flying...anyone could jump out of a plane when its on the runway and still survive... and of course, it also depends on whether you have a parachute or not.. Jayant,17 Years, India • contribs 06:23, 24 April 2006 (UTC)

Getting the door open may be rather difficult. As far as I recall the door won't open while in flight. Of course, if you rob everyone on the plane first, you could be the next D. B. Cooper.  :-) Dismas|^(talk) 06:35, 24 April 2006 (UTC)

I wouldn't say anyone could jump from the plane and survive... if you take the normal exit and there is no Jetway to step on to you will be in for a rather harrowing experience, and you could easily die from the stop at the end of the 25' fall if you land wrong on the Tarmac. --66.195.232.121 14:21, 24 April 2006 (UTC)

And your chances are even worse if you tried this from the upper deck of a Airbus A380. :) — QuantumEleven 14:36, 24 April 2006 (UTC)

Not a direct answer, but interesting: JAT Yugoslav Flight 364. Notinasnaid 09:42, 24 April 2006 (UTC)

"Is it possible to jump out of a 747?" While in flight? Almost impossible. Dismas is right, the pressure differential between the cabin and the outside at cruise altitude is so high that even if you were an olympic weightlifter you probably wouldn't have the strength to overcome it (airliner doors need to be pulled inward before they rotate outward, see [14]). You could create your own door with, say, a bomb - but that entails a whole raft of other problems.

Assuming you did find a way to leave the 747 in flight, could you survive the fall? It's very unlikely, but possible. You would probably black out from the low pressure, but are unlikely to die until you impact the ground. People have survived falls from very great heights without parachutes, but only under very special conditions. You need to land in something that would break your fall sufficiently gently - soft snow (and hope you don't get buried in too deep) or somesuch. The River Tiber (in reference to a recent popular book ;-) ) won't do. The link Notinasnaid provided is an example of a person surviving the plunge, and there are a handful of other accounts. — QuantumEleven 12:41, 24 April 2006 (UTC)

I think the answers above are pretty much correct. If you manage to get out of the plane you could survive but don't count on it, very few have survived. I think that falling over land would increase your chances (especially if there is snow). I don't think that water ever is soft enough, and even if it is you will most likly drown when you hit the surface of the water already unconsious from lack of oxygen. The article about Free-fall mentions three other known cases where people have survived falls at terminal velocity. Jeltz talk 11:22, 24 April 2006 (UTC)

Also a parachute could improve the chances of surviving the landing. – b_jonas 11:05, 25 April 2006 (UTC)

Being a pedant about the question the answer has to yes, because nowhere is it stated the plane is in motion, or in the air. --Blowdart 12:38, 25 April 2006 (UTC)

I'm sure i heared that the early test models of the 747s were fitted with an in flight escape exit. I belive the early test models of the A380 were too. So yes with a parachute and the correct exit installed you could do it in flight but on a production airliner with no special modifications it would be very hard. Plugwash 13:01, 25 April 2006 (UTC)

Early morning dilemma

When I arrive at my office I can either walk up four 6" steps or up a direct ramp which is about six times as long as the steps. I intuitively walk up the ramp as this looks easier than climbing the steps, but whenever I choose the steps it feels like they're less work, perhaps because the effort is expended over a shorter distance. Logic tells me I'm doing exactly the same amount of work whichever option I choose. Which would you choose and why? Shantavira 08:10, 24 April 2006 (UTC)

Well, you do the same amount of mechanical work either way, but if by "work" you mean total muscular energy expended, then surely one option is costlier than the other. It would depend on the details of your personal gait, but in general, I would guess that the ramp requires you to burn fewer calories, simply because your velocity doesn't change as much when you use it. Melchoir 08:24, 24 April 2006 (UTC)

Yes, that's an interesting point about the change of velocity, which I don't notice in practice. I shall try both options at an increased velocity and see how they feel. Shantavira 09:36, 24 April 2006 (UTC)

Another factor is that the ramp will cause you to lean slightly backwards, which causes you to expend more energy to move forward. This would actually help when walking down the ramp, though. I suggest you compare walking down the steps and ramp. I suppose I should also point out that if climbing 4 steps seems like a significant amount of work to you, you may need the exercise to get in better shape. Always taking steps (or ramps) instead of elevators and escalators can be good exercise, and taking the stairs is frequently quicker than waiting for an elevator anyway. StuRat 11:21, 24 April 2006 (UTC)

You are using different muscles, so the two would feel different, irrespective of work done "physics-wise". Have you checked if the distance - as would be measured by pedometer - is the same? --Seejyb 19:07, 24 April 2006 (UTC)

C operator overloading doubt

I must write a program in C, which of course doesn't support that feature. The thing is... operator overloading would be extremelly useful since the program performs lots of operations of complex numbers, already defined in a "tool" file written by me. How can I make a*b-sqrt(a^2/2) (for example) intelligible if I have to use a lot of functions? How C programmers got around this problem? Thank you for your time.

You could just make a function named sqrtCmplx, or something like that, but the other functions, equivalent to *, -, ^, and /, would indeed be ugly. BTW, I would think you could find an include file with complex number functions somewhere, rather than write your own, but since you've already done this part, I suppose it doesn't matter now. StuRat 12:54, 24 April 2006 (UTC)

You will likely need to break the expression up into multiple lines to make it easy to follow with all the new function names. As for making it readable, just include the simple version in a comment, to explain what is being done. StuRat 13:00, 24 April 2006 (UTC)

I think you'll find that if you use a lot of functions, then they become more intelligible with time. I agree that breaking down will help. Just more typing, it isn't more cryptic really. Notinasnaid 13:10, 24 April 2006 (UTC)

If your compiler supports the C99 standard, your expression could simply be written a*b-csqrt(a*a/2), if you use the complex types from the [complex.h] header. 84.239.128.9 18:53, 24 April 2006 (UTC)

Thank you all very much.

Evolutionary Questions

What is the evolutionary fuction purpose of sleep? It seems like sleep would be a huge disadvantage as it would leave one open to predators. How & why did sleep evolve then? Also, what is the evolutionary purpose of yawning? 199.201.168.100 12:34, 24 April 2006 (UTC)

Check out our articles on sleep and yawn - they should answer both questions. If there is something you don't understand, feel free to come back here and ask again! :) — QuantumEleven 12:40, 24 April 2006 (UTC)

I believe sleep developed because animals are specialized to be either diurnal or nocturnal. Diurnal animals (like us) are rather helpless at night without artificial light so spend the time recuperating and using as little energy as possible, during sleep. (An exception is during full moons, when we have enough light so we can go hunting at night, and hence the urge to go kill something during a full moon.) Nocturnal animals are similarly helpless during the day, in that they can be easily spotted by predators, so they sleep then. Some animals have taken the sleep concept a bit further, like cats, and sleep most of the time to limit energy consumption further. StuRat 13:12, 24 April 2006 (UTC)

Animals that saved energy by lowering their metabolism rate in a daily cycle were more successful than animals that didn't; apparently specializing for either dark or light was more successful. Once sleep existed in animals, animals that utilized this state for various internal functions (healing, reorganizing mental data, mental rehearsing of situations, etc) were more successful at surviving and reproducing than those whose genes less well utilized the sleep cycle. WAS 4.250 18:12, 24 April 2006 (UTC)

On sleep leaving animals open to predators, I don't think that's very much so. I mean, animals obviously defend themselves against this, either by sleeping in an alert way and getting awake as soon as they hear any noise, or by hiding in a hole or some other safe place when they sleep. – b_jonas 11:00, 25 April 2006 (UTC)

The brain is extremely active during sleep. It appears something important to the brain is going on, although research into exactly what is ongoing. --Ginkgo100 03:55, 26 April 2006 (UTC)

Another Evolutionary Question

Why can't I get laid? 199.201.168.100 12:34, 24 April 2006 (UTC)

Because you spend your time asking questions at the Wikipedia Ref Desk instead of going out and attempting to impress members of your target sex. — QuantumEleven 12:38, 24 April 2006 (UTC)

...and it also helps to make friends with them first. Shantavira 13:04, 24 April 2006 (UTC)

Perhaps you have a back problem? Try sitting down with your legs flat on the floor, and then lean your torso back slowly until it rests on the floor as well. Use your arms for support. Dysprosia 14:38, 24 April 2006 (UTC)

People get what they want when they tell lots of people what they want and they actively offer what those other people want. Different people want different things. Be clear about who you are and want you want. Listen carefully to what is communicated back both verbally and nonverbally. Some people want an illusion leading some to say lie to get laid; but most people just like a comfortable presentation to go along with the substance - like a meal at a restaurant looking good as well as tasting good and being nutritious. And remember, you have competition to out bid. (as do they) WAS 4.250 18:02, 24 April 2006 (UTC)

That is one of the best answers I've ever read here. I think. Grutness...wha? 03:19, 25 April 2006 (UTC)

And if what WAS says doesn't work either, it may be that you're unsuccessful in getting laid because you haven't considered attempting to lay, or it may be because you are not a chicken, and never will be.  freshgavinΓΛĿЌ  05:29, 26 April 2006 (UTC)

Heat generated by resting human body.

It appears to me that regardless of the ambient temperature my body generates substantial heat when I sleep. Is this an understood bodily function?

Your body is only attempting to keep itself at a more-or-less constant temperature (approx. 37°C) - you are a mammal, and mammals are warm-blooded. I would guess that your ambient temperature is very rarely at or above 37°C, so for any ambient temperature lower than that, your body is obviously a net generator of heat. This happens whether you sleep or not. We have a pretty good article on thermoregulation, which should answer most of your questions. If anything isn't clear, feel free to come back for more clarification! :) — QuantumEleven 14:30, 24 April 2006 (UTC)

Yes, it is well understood. If you too wish to understand, start here: Basal metabolic rate. WAS 4.250 17:53, 24 April 2006 (UTC)

Thank you very much. I apologize for not searching more diligently; the referenced articles are excellent. --BellCurve 20:26, 24 April 2006 (UTC)

Nutritional value of hemp seed

The information you provide about nutritional value of hemp seeds(http://en.wikipedia.org/wiki/Hemp) states that 100g of hemp seeds contain 2277.5 IU of vitamin D. This seems extremely hight. I have tried to verify this information and cannot find any data to support it. Can you provide your source of this information? Thank you, Kathy

I have placed a note in the article for someone to provide a citation or correct this. I have copied your question to Talk:Hemp - which is the discussion page for the Hemp article, which is where the editors of this article are most likely to see it. Thryduulf 15:16, 24 April 2006 (UTC)

Gender Differences

On a first note, this question probably is going to offend someone out there, and I would apologise dearly if this is so, but I am no troll and only relating of something I have always noticed. How is it that so many modern females may excell far better than the opposite sex in their school studies, yet still produce so few works of true distinguishing excellence in their future careers? And I am not merely speaking of the scientific careers that have long leaned in favour of men, either- even some careers commonly associated with women in school curricula such as the liberal arts, are still dominated in the wider world by men! It is reported that the genders score equally well on IQ tests, but how is it that it always, as seemed to me, far easier to fulfil the higher intellectual curiosities of women than that of equally educated men? Even when given more or less similar opportunities such unusual traits would still sometimes develope. I would be deeply grateful if someone may find a way of understanding these differences. Luthinya 15:00, 24 April 2006 (UTC)

Do you have any sources for actual statistics on this? It would probably help to show some real numbers, so one could trust the claim. - unsigned

Just as human males are geneticly taller on average than females, so too males are genetically more agressive and competitive than female humans, while females are genetically more cooperative. Different social structures reward different traits just as differnt sports reward different traits. WAS 4.250 17:46, 24 April 2006 (UTC)

A possible explanation is the suggestion that women have less capacity for abstract thought, which is required to make truly original and breakthrough achievements. For example, my cognitive psychology textbook in college presented women's inferior capability to rotate 3D images in their heads as fact. In a fairly recent interview, I've also heard a Cambridge University professor state that "women don't have creative minds", although the rest of the interview suggested that he may be quite biased. It's just a possibility to consider, but I can try to find out what the textbook was and where I heard the interview if you need sources for any research you're doing. In the meantime, you may want to have a look at our gender differences aticle if you haven't already. --Aramգուտանգ 18:44, 24 April 2006 (UTC)

"Abstract thought" is not the same as spatial reasoning. That statement is a crude generalization, and "Women don't have creative minds" even moreso. In the rush to find cognitive reasons for this perceived disparity, I think people are discounting a cultural and/or emotional one: to really excel in a field, a person needs a certain degree of dedication, and it could be that more women than men choose to sacrifice this degree of dedication in favor devoting more time to family life. Ginkgo100 03:50, 25 April 2006 (UTC)

I (independantly and unjustly) attribute it to two things, one of them being sexism. It's not hard to imagine the difficulties a woman would have had trying to breach the upper levels of intellectual society in the time of Newton or da Vinci, though I don't believe it's nearly as large a factor now as it was before the 20th century.
I also believe, with some evidence, that strong right-brain tendancies are more common in males than in females. Whether that really means anything is another argument, but certain "symptoms" such as left-handedness clearly indicate that women are much more left-brain dominant. If you believe in the all the right/left-brain mumbo-jumbo, then it gives you a nice way to explain why there are more well-known male eccentrics, famous male painters, gay hairdressers, and white-moustached scientists than females.  freshgavinΓΛĿЌ  02:42, 25 April 2006 (UTC)

One factor (among several) is that males tend to have more diverse abilities (a greater standard deviation than females), so males do tend to be a little over-represented among the most- (and least-) capable members of society. Peter Grey 05:30, 25 April 2006 (UTC)

A real problem is that when you look at it from afar, things like "intelligence" and "success" and "ability" seem such obvious terms. But when you look close up, they become very 'fuzzy'. As an old teacher of mine used to say, sharks have been round a few hundred million years. They probably won't consider humans a successful species until about 300 million A.D. or so. Questions such as 'What is intelligence?' are very problematic in this sense, and the articles on intelligence and emotional intelligence will lead you to some of the debate. In the realm of the questions you are asking, a parallel question might be phrased, is it "more successful" in a "future career" to to be more commonly liable to sexual harrassment and workplace bullying, and to die younger from stress, as men do, and then to claim greatness for having bought career progress at such heavy cost? Success is a very arbitrary term. men and women are not only wired slightly differently, but strike slightly different balances between such things as social prestige, family, inward and outward directed motivation, and so on. What success, at what cost, by what standards, ignoring what else, and how? Thats what your question misses and where you may find more of an answer. FT2 (Talk) 19:11, 25 April 2006 (UTC)

Tri-beveled needles & Anti-Coring

Hello, I work for a medical supply company, and I am currently doing a presentation on needles. I was wondering what Tri-beveled means as well as Anti-coring. Any help would be greatly appreciated.

Colleen

For anti-coring, think of an apple corer. An apple corer is like a tube that punctures the apple and holds the apple core inside of it when it is withdrawn. Often it would be undesirable for a medical needle to behave like this; you want it to puncture, but not let tissue enter the needle itself. This also comes up in the context of syringes used for gas chromatography; a needle that takes a core can ruin what used to be a gas tight seal.

I don't know about tri-beveled. Try the manufacturer's tech support. ike9898 16:33, 24 April 2006 (UTC)

An anti-coring needle is designed to minimise the punching out of a piece of material (e.g. human tissue) which can then get stuck in the shaft of the needle, either blocking it, or depositing unwanted material at the site of injection, or leaving a punched out hole in the tissue after being withdrawn. The most commonly used medical example is the Tuohy needle, used for epidural anaesthesia.

A triple-ground, tri-bevel hypodermic needle is one with a bevel which has been ground or honed in three different planes. This is to try to achieve a compromise between cutting ability, rigidity of the cutting tip (a long bevel cuts easily but can bend or curl over at the tip), ease of introducing and advancing the needle (a short bevel feels "blunter" and the needle advances less easily), and distance from the tip of the needle to the start of the tubular shaft. This last factor is important since one does not want the tip of the needle protruding far beyond the tubing part through which the user may wish to draw blood or give an injection.

Look at the tip of one of your thicker needles, you will see the 3 planes: The bevel closest to the hub is at a relatively flat angle in relation to the shaft of the needle (that would be the start of a long bevel). About halfway to the tip of the needle you will see a change in plane (angle of bevel), with two additional ground planes (bevels) starting, one on each side of the main initial bevel, and rotated slightly, so that the very tip of the cutting edge looks triangular, not round or flat. This is the standard grind for hypodermic needles, also called a diamond bevel, or lancet. A well-made standard needle would be expected to have such a bevel (i.e. it shows compliance with accepted standards, and is not a "special feature"), and deviations from this would mostly be for special uses. --Seejyb 20:29, 24 April 2006 (UTC)

Cryogenics

What was the first country to use cryogenic technology?—The preceding unsigned comment was added by 207.28.159.13 (talk • contribs) .

I'm not sure; have you looked at Cryogenics? Andrewjuren(talk) 20:49, 24 April 2006 (UTC)

Distribution of mass in Earth

Hey. So, it seems to be correct that the further into Earth you get, the less gravity is there to pull on you. Therefore, at the correct center, there's a theoretical nil-gravity. My question related to that comes from that the core must be under pressure in order to be so warm and stuff, from the particles above. Does anyone know, in theory, the distribution of MASS in earth? There are all the nice pictures with half or three quarter of a globe, showing what parts are what, but I don't see any explanations for the mass. 213.161.189.107 17:26, 24 April 2006 (UTC) Henning

The article Structure of the Earth has some information on the density, but not much. You might get better results if you include the phrase "radial density profile" in your search. For example, I found: http://arxiv.org/pdf/astro-ph/9909038 —Keenan Pepper 18:02, 24 April 2006 (UTC)

I have trouble understanding the question, and my main thing is geophysics, etc. Perhaps after you have looked at the above references, we can point you to some other links. --Zeizmic 02:12, 25 April 2006 (UTC)

The Human Genome

Where can I find the exact sequences for the human genome, and not just a description of the project?

Just to make sure you're clear, there is no such thing as the "exact" human genome sequence. The genetic sequence varies by individual, otherwise we'd all be clones. To search for sequences within the human genome, look at the External links section of the Human Genome Project. Andrewjuren(talk) 20:44, 24 April 2006 (UTC)

The ensembl site has these, but you need to know what you are looking for. To me it's like heiroglyphics. Can one say that it will be long before all the data becomes information, or do I misinterpret the situation? --Seejyb 20:56, 24 April 2006 (UTC)

It's like hieroglyphics to me too, but fortunately, I understand a little of both genomics and reading hieroglyphs. :) - Mgm|^(talk) 07:58, 26 April 2006 (UTC)

Visit our article on the Human Genome Project and look through the external links. There are links to Project Gutenberg's raw text dumps of the entire genome; each chromosome is presented as one 'book'. For an annotated genome, try poking around at Ensembl. (Follow the link and click on Homo sapiens; click on a chromosome and zoom in from there.) TenOfAllTrades(talk) 20:49, 24 April 2006 (UTC)

POOP IS GOOD

My Question is why is poop brown? Because I poop alot and its always brown but sometimes its a sand color, and what determines the shape of poop? Thanks for any help. —The preceding unsigned comment was added by 68.239.192.119 (talk • contribs) .

If you had read the article on feces, you would know that they get their brown color from bile and dead red blood cells. —Keenan Pepper 20:43, 24 April 2006 (UTC)

Human feces is a better place to start. WAS 4.250 21:03, 24 April 2006 (UTC)

The shape of "poop" is obviously determined by it's passage through the anus, and the texture and consistancy are determined by the character of the present material.  freshgavinΓΛĿЌ  02:21, 25 April 2006 (UTC)

Think of toothpaste. It is the fact you squeeze it out through the hole in the tube that gives it its shape. (Now how will you keep from smiling when next brushing?) Shenme 02:51, 25 April 2006 (UTC)

Are you sure about that? I'd been under the impression that it was because of the shape of the rectum. It seems too firm to have been reshaped only moments before. Black Carrot 01:52, 26 April 2006 (UTC)

I understand but could not confirm that the curved shape human feces often has is a result of the curved shape of the rectum. --Ginkgo100 03:27, 26 April 2006 (UTC)

Actually, it probably depends, like Black Carrot says (I wonder if that name is a reference to this topic), on how firm the module is. I'd say both the rectum and the anus are factors in determining the post-expulsion shape.  freshgavinΓΛĿЌ  05:24, 26 April 2006 (UTC)

Brain Map showing Broca's Region

I'm looking for a simple sketch or drawing of the brain showing basic areas including Broca's Region. Is there a site I can find this and download it?—The preceding unsigned comment was added by 172.185.95.29 (talk • contribs) .

See the article on Broca's area. Andrewjuren(talk)

You might also be interested in Brodmann areas (though see [15] for better images). Broca's area comprises areas 44 and 45. Cheers, David Iberri (talk) 00:36, 25 April 2006 (UTC)

Polarized Objects

Most people are firmiliar with Static Electricity, and most people know about most of it's concepts, right? Well, after looking up a problem in my homework today (Find a definition using any source) I could not find any definition for a popular term "Polarized Objects" anywhere, I have looked in many dictionaries, but it is nowhere to be found. --68.61.181.253 21:04, 24 April 2006 (UTC)Rachel needs Help!

I am uncertain of what you mean by "polarized object". Perhaps you are referring to a dipole? Or perhaps about polarization? -- Andrewjuren(talk) 21:08, 24 April 2006 (UTC)

In electrostatics, any section of any object may be polarized; if an object is characterized by a large amount of polarization, or is uniformly polarized, one could say that it was a polarized object. But such polarization is typically a transient thing in response to an electric field; the analog to a permanent magnet, the electret, is very rare. But maybe that's what you want after all? You might also simply mean "charged object". --Tardis 21:50, 24 April 2006 (UTC)

Can you calculate orbits' stregnth?

I found out about the gravitational formula:

$Force=Gravitationalconstant\times {Massofobject1\times Massofobject2 \over distance^{2}}$

So I calculated the force between the Earth and the Moon (1.89 X 10²⁰ N); the force between the Earth and the Sun (3.55 X 10²² N); and the force between the sun and Alpha Centauri, the nearest star (1.76 X 10¹⁷ N).

Since the Earth/sun force is greater than the Earth/moon force, does that mean that the orbit between the Earth and the Sun is stronger than the orbit between the Earth and the Moon? Or does the force get bigger with bigger objects? Jonathan ^talk File:Canada flag 300.png 22:11, 24 April 2006 (UTC)

Um... "stronger orbit" and "weaker orbit" are not phrases used in celestial mechanics, so I'm not sure what you mean. Could you clarify your question? Melchoir 22:17, 24 April 2006 (UTC)

There is certainly more force exerted between the Earth and the Sun, as you've found out.. are you asking whether it would be harder to knock the Earth out of the Sun's orbit than the Moon out of the Earth's? The actual size of the object shouldn't really matter in any of this as far as I know, it's just that heavier objects tend to be larger. -- Mithent

Right, the important exceptions to this tendency being degenerate stars, which actually get smaller as they gain mass. Melchoir 22:44, 24 April 2006 (UTC)

The orbit is "stronger" in that you need more energy to tear the Earth off the Sun than to tear the Moon off the Earth. This is, however, determined by the potential energy, not by the force. Conscious 08:34, 25 April 2006 (UTC)

Conscious is right; the idea of the "strength" of an orbit is most analogous to how tightly bound the objects are. To go into the mathematical nitty-gritty, the potential energy is given by $U=-Gm_{1}m_{2}/r$ (where U is the potential energy, G is the gravitational constant, and $m_{1}$ and $m_{2}$ are the two masses, separated by a distance r). The negative of this is the work you'd need to do against the gravitational force to separate the two objects to "infinity" (but you can think of this as "arbitrarily far away" if infinity bothers you; incidentally, if you've had any exposure to calculus, because gravity is a conservative force this is just the integral of the gravitational force formula). For the Earth-Sun system this works out to $\approx 5.3\times 10^{33}$ J; for Earth-Moon $\approx 7.7\times 10^{28}$ J. So you'd need seventy thousand times as much energy to separate the Earth from the Sun as you would to separate the Moon from the Earth. --Bth 09:21, 25 April 2006 (UTC)

Since an orbiting object already carries kinetic energy, you only need to provide 50% of that amount. In fact, if you apply it in the satellite's frame of reference, you only need 8.6%. Now, since there's nothing to push against out in space, and the various bodies are moving with respect to one another, there's no Correct Frame from which to measure the energy, and a more physically relevant measure of the "strength" of an orbit is the impulse it takes to break it. As in, how much rocket fuel would it take? But then to go from energy to impulse you'll have to divide by a speed, which will throw off the scaling relationships yet again. Melchoir 10:01, 25 April 2006 (UTC)

Thanks for all the answers, but maybe I should rephrase my question: I just want to know what these numbers mean:

Earth/Moon: (1.89 X 10²⁰ N)

Earth/Sun: (3.55 X 10²² N)

Sun/AC: (1.76 X 10¹⁷ N)

I thought maybe I could use this formula to calculate and compare various orbit's strength. And yes, what I meant by stronger orbit was harder to knock something out of its orbit. Jonathan ^talk File:Canada flag 300.png 16:13, 25 April 2006 (UTC)

All that those forces mean is given by Newton's second law; they're just mass times acceleration. The numbers are great for getting an idea of the ridiculous forces at work in the sky, but I'm not sure if comparing them against each other has much of a meaning. Melchoir 16:55, 25 April 2006 (UTC)

The formula you quote at the beginning, is the formula for the force two point objects (bodies) exert upon each other. So for example, the earth exerts a force of 1.89 X 10²⁰ N on the sun, and the sun exerts a force of 1.89 X 10²⁰ N on the earth. This force, not coincidentally, is also the force needed to keep them in an orbit about each other, which is why they have come to orbit at the exact distance they do - because its the distance where the force needed to orbit is the same as the force they exert on each other.

The "how hard to knock out of an orbit" is a different question. As you peturb an orbit it becomes more and more eccentric, and irregular, or unstable. any amount of force applied to one or the other will affect their orbit. To "knock them out of orbit" however, the easiest way to think of it is, how much work would it take, to completely separate them, to make them move completely apart and not remain in an orbit of any kind. The velocity needed for that is called escape velocity, same as for spaceships, and so a better answer is a matter of the energy required to do so, so it will be measured in Joules not Newtons. In other words, rather than measuring the force needed to change an orbit (because any force changes an orbit anyhow), scientists prefer to ask what is the amount of work (or energy) that must be added to the system to cause the two to be able to achieve separation. FT2 (Talk) 18:59, 25 April 2006 (UTC)

OK, so the short answer is: The Force between two object and the orbit between two objects are two different things? Jonathan ^talk File:Canada flag 300.png 17:08, 26 April 2006 (UTC)

How to plot simple graphics in X-windows

How do I get a 13 year old student to plot a simple graphics on X-windows on linux? He wanted to be able to plot y=sin(X*2*PI/200) on a window in X-windows. At the moment he is using gnuplot to plot it but we wonder how to do it directly to a window without using gnuplot. Can it be done in C ? Python? Ohanian 23:05, 24 April 2006 (UTC)

To my knowledge, there is no easier way to plot graphs on X than gnuplot. --Kainaw ^(talk) 00:08, 25 April 2006 (UTC)

I'm not sure if I know one, but I hope there is. Gnuplot, for all it's good sides, is not exactly a paradigm of user-friendliness. --BluePlatypus 00:28, 25 April 2006 (UTC)

Probably want Octave or Maxima. - 128.32.48.131 01:44, 25 April 2006 (UTC)

For my son, we found a Java function plotting program. Did all the sin functions, etc. --Zeizmic 01:48, 25 April 2006 (UTC)

An excellent age to begin programming for the X Window System. To answer your question, the lowest level interface to the X protocol is Xlib, a C library. There are a number of tutorials on Kenton Lee's X Window System site. Someone who could use a C compiler and gnuplot could probably copy one of the sample programs and alter it to graph a function.

There are a number of widget toolkits built on top of Xlib, with bindings for various languages. Widgets are for building GUIs, but most would also allow for drawing graphics primitives (the points and lines that make up your graph) directly to an X window. Another way to render graphics on a linux box would be to use OpenGL and bypass the X server (if the Direct Rendering Infrastructure is available.) Have fun. EricR 02:25, 25 April 2006 (UTC)

April 25

Fractals and turbulance

Is there a link between fractals and turbulance? Turbulant patterns seem to be fractal but turbulance is supposed to be chaotic, is this true?

Well, Fractal, Chaos Theory and Turbulence all link to one another. And yes, I believe there's a strong connection. Black Carrot 01:26, 25 April 2006 (UTC)

Fractals and turbulance are both examples of chaos, at least in the mathematical sense. Peter Grey 05:34, 25 April 2006 (UTC)

As I recall, VOB files are already in MPEG format. Try renaming them to .MPG and see if they play. If so, then virtualdub-mpeg website can directly recode them to AVI format in any codec or compression you choose. FT2 (Talk) 01:53, 26 April 2006 (UTC)

Do fish have lips?

does anybody know? I'm trying to settle a bet.

If you are referring to an opening around the mouth, yes, fish have lips. If you are referring to a ring of muscles around the mouth opening, most fish have lips. Some have hardened beak-like openings for smashing coral. If you are referring to a thin area of skin with excessive nerve endings, most fish do not have lips. If you simply mean a colored region around the mouth, many of the tropical fish have brightly colored lips - some are even pink. Of note: the product "fish lips" I've found in Asian markets is actually just shark skin (at least that is what the merchants have told me). --Kainaw ^(talk) 01:15, 25 April 2006 (UTC)

My attempts to kiss fish have been somewhat unsuccessful; however, this could possibly be due to a lack of desire on the part of the fish, rather than any deficiency they may have in the lip department. Phileas 06:51, 25 April 2006 (UTC)

Perhaps you should take advice from Peter Griffin (assuming you've see the "I've had sex with all these fish" episode). --Kainaw ^(talk) 13:05, 25 April 2006 (UTC)

the date of creation

I have calculated the times of more than a dozen comets and they trace back to one year, this was 7205 years ago. I also found this was the same date the bible has hidden since St Jerome wrote the Vulgate in about 384 AD.These are some of the comets Haley-95 orbits of 75.63 years. Hale/Bopp had 3 orbits of 2398.66666 years, Swift-Tuttle(109p) orbited 55 times of 130.745 years, and Schwassmann-Wachmann(73p) will orbit 1327 times by next month with an orbit time of 5.42963 years. I have other proof that the earth is but 7205 years old.

Homosayswhat? Black Carrot 01:22, 25 April 2006 (UTC)

Bigotsayswhat? - 18:15, 25 April 2006 (UTC)

On a more generous note, have you tried calculating where all of those comets were 7205 years ago? If they appear to have originated from the same point, that could be a scientific discovery worth publishing. Good luck! Melchoir 01:29, 25 April 2006 (UTC)

Oh yes. I remember it like it was 7205 years ago. I was just getting up for a morning bowl of raisin bran and I couldn't find the damn light. Then a lovely fellow - Oh, what was his name? Something like Yahoo or No Way or Yahweh - anyway, he just said "Let there be light" and I heard him flip a switch and the light turned on. I acted very impressed, but I remembered changing the bulb just a couple days earlier. I asked him to join me anyway. I was feeling very foggy from a hard day's night. I mentioned it to him and he said he'd make a song out of it later when he got around to learning the drums. Then, he gave me a couple pills and the foggy void separated into a clear view of the heavenly sky above and a firm earth below my feet. I poured him a bowl and he got all weird about it. He kept separating the piles of bran into little mounds with oceans of milk between them. He pushed the raisins in and commented how they bobbed around like little fish. I agreed, but it was getting rather trying about this time. Anyway, to make a long story short, I asked him if he remembered the date of creation. "Sure," he said. It was exactly 6.3 billion years before that. He remembered it just like it was 6.3 billion years ago. He was just getting up for a morning bowl of raisin bran... --Kainaw ^(talk) 01:30, 25 April 2006 (UTC)

7,205 years ago, yes. And on a Thursday. I never could get the hang of Thursdays. -- Filliam H Muffman 02:05, 25 April 2006 (UTC)

Actually... assuming our unsigned friend calculated the orbits on the same day that Mr. Black Carrot replied, then the earth started on a Wednesday (5199 BCE). I'm a little confused about his calculations though. What does the origin of comets have to do with the age of the earth? I'd rather give him the benefit of the doubt and have him come back and explain his theories.  freshgavinΓΛĿЌ  02:16, 25 April 2006 (UTC)

• To suitly emphazi, that's 5199 BCE if you use a year zero, 5200 BCE if you don't. -- Filliam H Muffman 02:53, 25 April 2006 (UTC)

Damn. And I feel bad for attempting to block you from using a H2G2 quote too.  freshgavinΓΛĿЌ  05:16, 26 April 2006 (UTC)

What exactly are the times of more than a dozen comets? Peter Grey 05:37, 25 April 2006 (UTC)

Like the times of exactly a dozen comets, but more! -- SCZenz 07:07, 25 April 2006 (UTC)

Ha, ha. Maybe this belongs in Wikipedia:Reference desk/Pseudoscience. --Andrewjuren(talk) 07:39, 25 April 2006 (UTC)

Congratulations you've managed to calculate the age of recorded history. Now use your awesome powers of deduction to resolve your date of Creation with the fact that Radio Carbon-14 dating which breaks down to Carbon-12 at a fixed rate, and is renewed in living organisms dates bones and plants over 10,000 years. Not to mention several other radioactive isotopes which also have fixed rates of radioactive decay have dated rocks at around 4,000,000,000 years of age. --Tollwutig 14:24, 25 April 2006 (UTC)

Strings

Are thre anti-strings? —The preceding unsigned comment was added by 207.255.31.124 (talk • contribs) .

Your question needs more context before we can answer it. What are you talking about? —Keenan Pepper 02:55, 25 April 2006 (UTC)

If you're asking whether string theory includes antimatter states, the answer is yes. -lethe ^{talk +} 03:11, 25 April 2006 (UTC)

But there are not any "anti-strings," like how we see antimatter and matter annihilating. -- Mac Davis] ⌇☢ ญƛ. 04:24, 25 April 2006 (UTC)

The woodwind section is often very anti-string, if that's any help. Grutness...wha? 03:20, 25 April 2006 (UTC)

They're really just acting that way to hide the uncontrollable physical attraction. Melchoir 03:27, 25 April 2006 (UTC)

Aluminum- going from an ion to an atom

How many electrons does aluminum gain by going from an ion to an atom? —The preceding unsigned comment was added by 67.150.42.98 (talk • contribs) 03:19, 25 April 2006.

If you want to know how many electrons an aluminum ion will gain, you should look at it in reverse: how many electrons does an aluminum atom loose to become an ion? Because it is in group III of the periodic table, it has three valence electrons that are readily removed from the atom. When this happens, it becomes a Al³⁺ ion, so the answer is three. Hope this helps.--Chris 03:23, 25 April 2006 (UTC)

Bauxite

How is bauxite turned into a metal? —The preceding unsigned comment was added by 67.150.42.98 (talk • contribs) 03:29, 25 April 2006.

Bayer process Melchoir 03:33, 25 April 2006 (UTC)

And then Hall-Héroult process. Melchoir 03:33, 25 April 2006 (UTC)

thanks!--Ll10398 03:45, 25 April 2006 (UTC)lily

Properties of Aluminum

What are 10 different properties that make aluminum than other metals? —The preceding unsigned comment was added by 67.150.42.98 (talk • contribs) 03:36, 25 April 2006.

Ahem: Do your own homework. If you need help with a specific part or concept of your homework, feel free to ask, but please do not post entire homework questions and expect us to give you the answers. Melchoir 03:37, 25 April 2006 (UTC)

Are you writing an essay about aluminum or something? Did everyone in your class get their own element? Anyway, I'm sure there are at least ten interesting properties in the article Aluminium, so don't bother us anymore unless you really search and still can't find what you're looking for. —Keenan Pepper 03:51, 25 April 2006 (UTC)

Research is useful...--Tollwutig 14:27, 25 April 2006 (UTC)

would like to know anything about Arlington Chem Co. circa 1890s.

I would like to find out anything about Arlington Chem Co. circa 1890s if anyone knows anything I would be grateful.

start here WAS 4.250 15:56, 25 April 2006 (UTC)

"John Andrus (1841-1934) was born in Pleasantville, New York, graduated from Wesleyan University and soon moved from teaching school to pursuing his talents as an investor and businessman. His primary operating business, the Arlington Chemical Company, manufactured typical medicines of the late 1800s and distributed them worldwide." [16] WAS 4.250

Physics Dilemma

I have a question that's based on theory of physics.

Suppose you have a person of a certain weigh in a bucket where he/she is pulling themselves up by tugging on the other rope. So that's a pulley, he/she is on one side in the bucket, and the rope is over the pulley, and then they pull the other end, just to clarify.

So, my physics teacher told me that if the person was to pull at the force of gravity on the person going up, that the person would go up in a constant speed, no acceleration. So, if the tugging action is equal to the weight, it moves up in a constant speed. But how would you pull yourself have way up for example, and then stay in that position? What force is keeping you balanced? She told it was the same force, except that the rope was exerting the force up when it was moving, and then when it was motionless, that the same force was being directed into a different direction. Class was over and I didn't get the last bit.

So if someone could explain this well as they can it would be greatly appreciated. Thanks a lot.

C-c-c-c 05:11, 25 April 2006 (UTC)

If all the forces on a body sum to zero, then it doesn't accelerate; this is universally true whether the body is moving or not. If you're not accelerating, then the rope/bucket must be exerting an upward force equal in magnitude to your weight. It'll never be in any other direction.

On a different note, "force of gravity" is misleading. Sitting in the bucket, you don't have to pull the other side of the rope down with a force equal to your own weight; you only need to exert half of that force. This example is actually touched on at Mechanical advantage. Melchoir 05:35, 25 April 2006 (UTC)

Thanks, but I was wondering if you could explain the idea behind that, why would it be half your weight? I've never seen any of those equations in the link you put up. Thanks again.

C-c-c-c 05:47, 25 April 2006 (UTC)

Hmm, interesting. I haven't thought about this problem before. Assume that you are standing in a bucket. There is a rope tied to the bucket, looped over a fixed pulley, and which passes by you again on its way down. You're holding on to the rope.

For our example, all forces will be in the vertical direction; assume negative forces point down. The force of gravity on you (your weight) will be -m·g: your mass m times the gravitational acceleration g.

If you pull on the rope with a force f, you'll be directly exerting that force to lift your body. In addition – and this is the important trick – the rope (in tension) will be exerting an additional force f. To remain steady, the forces acting on you must sum to zero, so:

0 = -m·g + f + f

f = (1/2)·m·g

Conceptually, you could also think of it has being a bucket with a rope looped over a pulley where both ends of the rope are tied to the bucket. (Here, your arms just act as the knot that ties the other end of the rope down.) Your weight is supported by two ropes; each rope holds half the weight. TenOfAllTrades(talk) 06:05, 25 April 2006 (UTC)

Wow! That actually makes sense! And it's so simple too, but not obvious at all at first. Thanks a lot!C-c-c-c 06:18, 25 April 2006 (UTC)

what's definition of tension?

in the question above why's it 0 = =mg + f + f & not mg - (f+f) because the tension is opposite direction of gravity rite? what's tension exactly how would u define it. also its always opposite of gravity rite? or no? can some1 explain thanks 06:37, 25 April 2006 (UTC)

• Tension is the force experienced when a rope is pulled, and is equal and opposite at the ends. If something is hanging from a rope, then tension is balancing the vertical force of gravity. Try a free body diagram of a section of the rope. Peter Grey 06:52, 25 April 2006 (UTC)

Psychiatrist's view of a religious person

Assume for a moment that people believing in a god isn't a common thing. Instead it's the kind of thing that may make someone proclaim, "That there is crazy talk!". With that in mind what would a psychiatrist's diagnosis be of a person who believes in an omniscient and omnipotent god who nobody has ever been able to prove exists? Dismas|^(talk) 08:02, 25 April 2006 (UTC)

There are people who believe in aliens amongst us, but mostly they're just living otherwise normal lives. In your scenario, people believing in a god might be regarded as eccentric, but not requiring treatment unless they believe their god requires them to, for example, kill all non-believers.-gadfium 08:09, 25 April 2006 (UTC)

It would depend on the patient's behavior. Example: saying Heaven is better than Earth is not considered "crazy"; but trying to go there now on purpose because it is better (by suicide) is considered crazy. WAS 4.250 15:38, 25 April 2006 (UTC)

Under the DSM-IV, probably "delusional disorder". The current definition of the symptom is a "fixed false belief, excluding those that are part of a religious movement". If you remove that religious caveat, you have a delusion, a symptom of psychosis, and the diagnosis would depend on the presense or absense of other symptoms (such as hallucinations). In the absense of other symptoms, probably "delusional disorder" would win the day. - Nunh-huh 18:13, 25 April 2006 (UTC)

Of course, the other opposite question arises. Mystics would consider that not being aware of more than the consensus reality we see around us, is somewhere between ignorance, delusion and illusion too. FT2 (Talk) 18:42, 25 April 2006 (UTC)

Fortunately, mystics can't civilly commit anyone, so their opinion matters mainly to themselves. - Nunh-huh 20:07, 25 April 2006 (UTC)

Thanks for the replies, everyone! Dismas|^(talk) 01:40, 26 April 2006 (UTC)

Insane Psychiatrist

Is it true that an insane person isn't allowed to study psychiatry/psychology? --Username132 (talk) 11:32, 25 April 2006 (UTC)

That is not true. WAS 4.250 15:38, 25 April 2006 (UTC)

Recently I came across a study which suggested that an above-average percentage of those studying psychology is made up of mentally instable persons, however you define that; a number mentioned was 60%, whatever that is worth. I have also been told that the curriculum is made up so as to not appeal to that type of person who wants to get in because he is obsessed with his own disorders, at least at my university. Apparently they try to bore them out :D --Dr. Zarkov 17:27, 25 April 2006 (UTC)

For what it's worth, I'm currently applying for a master's degree program in clinical psychology, and so far there's been no mention of psychological screening for applicants. --Ginkgo100 03:18, 26 April 2006 (UTC)

I'd be very skeptical of this rumor. It has urban legend written all over it. Bhumiya (said/done) 04:46, 26 April 2006 (UTC)

• You might not be allowed to practice phsychiatry, but I don't see why they should stop insane people from studying it. - Mgm|^(talk) 08:03, 26 April 2006 (UTC)

This is NOT true. My girlfriend is majoring in psychology. 12.183.203.184 04:20, 27 April 2006 (UTC)

Netherlands And Rising Sea Levels

Based on the threat of rising sea levels and the Dutch government's plan to give some land to the sea in coming decades, would you agree that property in The Netherlands would be a bad investment? Culturewise, what where would be the next best place? Belgium? -Username132 (talk) 08:06, 25 April 2006 (UTC)

I have not heard about this, but I suppose waterfront property may not be the best investment. Nevertheless, as we have seen in Vancouver, BC, Canada, when space is limited, prices go WAY UP, so investment would be a good thing. As for the culture... that's hardly a scientific question. Andrewjuren(talk) 08:21, 25 April 2006 (UTC)

The threat is unknown. Sea level is largely dependent on local pressure, temperature, salinity, etc. Some parts of the ice on Earth are melting, some are freezing, some are not doing anything, and some are just moving. -- Mac Davis] ⌇☢ ญƛ. 10:44, 25 April 2006 (UTC)

Sorry, MacDavis, I have to disagree with you there. The threat is definitely there, take a look at sea level and sea level rise, especially the first graph on both pages. Sea level change is global (because water is a liquid and so spreads itself out evenly), and it is definitely rising, there is no debate about this - satellites can measure sea level to an accuracy of a millimeter, and data collected over the past decades shows a steady rise of about 3mm a year (see here). There are several low-lying islands in the Pacific which have seen their land area greatly reduced over the last fifty years because of this. The question is how much it will rise, but even the lowest estimates put a significant strain on the Dutch sea defences over the next decades. — QuantumEleven 11:44, 25 April 2006 (UTC)

While it is a concern, do not forget that the Netherlands is already for over 50% below sea level, and dykes, levies and dunes have kept it dry in the past few centuries with only one major flooding(The one in zeeland in 1953). Most prognosis for the rise of sea level talk about 30cm to 70cm until 2100, something that should be manageable, although quite costly. Do not confuse this with the other waterworks project currently going on, which is to create basins for the 3 major rivers because altered weather has increased the chances of flooding from those. However, i'm not sure i'd advice anyone to invest in property in the Netherlands, since 60 years of housing shortages have pushed house and land prices to very high levels. As for what are related cultures, i'd guess that Belgium, Germany and the scandivian countries would probably be closest. SanderJK 11:56, 25 April 2006 (UTC)

This is getting slightly offtopic, but you might be wise to look at this article before you think too hard about buying investment property anywhere...--Robert Merkel 05:05, 26 April 2006 (UTC)

Refering To A Research Group

During my reading I've read of a research group refered to as the "Pabo group", being lead by someone called 'Pabo'. I need to refer to three papers published by

DAVID J. SEGAL, BIRGIT DREIER, ROGER R. BEERLI, AND CARLOS F. BARBAS III

Birgit Dreier, Roberta P. Fuller, David J. Segal, Caren V. Lund, Pilar Blancafort, Adrian Huber, Beate Koksch, and Carlos F. Barbas III

Birgit Dreier, Roger R. Beerli, David J. Segal, Jessica D. Flippin, and Carlos F. Barbas III

Segal and Drier occur in all instances, but some of the work was carried out at more than one laboratory. So can I refer to a specific group? --Username132 (talk) 09:36, 25 April 2006 (UTC)

Hrm. I'd say something like "Segal, Dreier and collaborators (Segal et al XXXX, Dreier et al YYYY, Dreier et al ZZZZ) [did whatever they did]" where XXXX etc are years (if YYYY=ZZZZ then use YYYYa and YYYYb). If I needed to refer to the same work repeatedly I'd do "Segal, Dreier and collaborators (Segal et al XXXX [SXX], Dreier et al YYYY [DYY], Dreier et al ZZZZ [DZZ])" at the first appearance and use the abbreviations I'd established thereafter to refer to whichever paper was relevant for the point I was making, probably treating the abbreviation as I would the names written out in full (eg, "DZZ showed [some exciting result]" for "Dreier et al (ZZZZ) showed ..."). But that's because I'm used to (the astronomy variant of) Chicago-style science citation; I don't know how similar that is to biochem. I'd be wary of deciding that they were "the Someone group" unless they're already widely referred to as that and/or one of the people is very clearly much more senior. --Bth 12:25, 25 April 2006 (UTC), not logged in

Scientific publications list the group leader as the corresponding author, who is typically marked with an asterisk. Dr Zak 20:20, 25 April 2006 (UTC)

yes and no - it depends on the type of scientific publication - there are many different formats for referencing and citation. Psychological journals use APA, for example, which is different from the method you mention. Grutness...wha? 02:24, 26 April 2006 (UTC)

If there is one person marked out to whom correspondence should be sent, would it be correct to assume that they were the group leader? -Username132 (talk) 05:04, 27 April 2006 (UTC)

Microprocessor Programming

I am currently syuding microprocessor programming.We can multiply two numbers by repeated addition of one number; other number of times.But then how does the scientific calculator do decimal multiplication and all as the numbers dont consist of integers??Ex 2*3=2+2+2 or 3+3 but 2.3*5.6???

A calculator will store decimal numbers as either fixed point or floating point. These are special ways to store information about a number. Fixed point allows a certain fixed number of decimal places, while floating point stores an exponent and mantissa. If a microprocessor chip does not include direct support for floating point, it is a huge project to create it, but the principles are fairly simple, so long as you understand what the arithmetic rules would be for arithmetic on two numbers in exponent and mantissa form. Notinasnaid 12:25, 25 April 2006 (UTC)

Multiplication algorithms are executed by Arithmetic logic units. WAS 4.250 15:30, 25 April 2006 (UTC)

Repeated addition is about the worst method of multiplication. Long multiplication is very simple in binary and this is the method most computers use for normal multiplication. It can be implemented in either hardware or software (software being the norm on some very low end microcontrollers hardware on anything else)

As for non-integer types the basic idea is you multiply the mantissas and add the exponents. then if nessacery you normalise.

e.g. in decimal (most computers would do this in binary but the principles stay the same) 2.3*5.6 = 23*10^-1*56*10^-1=23*56*10^-2 Plugwash 15:42, 25 April 2006 (UTC)

The answer is it depends on the calculator. It's important to distinguish between integer/fixed point/floating point representation, binary/decimal representation, and for decimal the encoding of digits (BCD, Densely Packed Decimal, Chen-Ho encoding). For instance, a floating point number may be stored with a binary integer significand and densely packed decimal integer exponent. Also keep in mind that a number may be represented in one form, but arithmetic may be performed in another, see: Intel BCD opcodes.

If you are looking at a scientific calculator, you are probably dealing with some kind of floating point decimal and IBM has a great site with links about decimal representations and arithmetic. EricR 16:32, 25 April 2006 (UTC)

The representation of a number can undergo many changes prior to and after the multiplication. I once saw a computer program that converted numbers back and forth between ASCII, BCD, and binary as the data passed between subroutines written by diferent people and this was just for small integers! A handcrafted program in assembly I saw went right from the keyboard-key-identify-buffer-contents passed by the keyboard-control chip to binary integer representation it sent to a multiplication-register in the CPU chip. (ok, ok, "right from" condenses a lot of get interupt, get byte & store, type detail...) WAS 4.250 18:30, 25 April 2006 (UTC)

Anyone run a website?

That is not computer related (and is in English). If you have a counter on the front page, I would like to know what statistics you have on the various operating systems that computers visiting your website run. I write a blog, but have contaminated the stats by visiting it myself. Presumably your site will not be contaminated to any large degree, if you don't visit it often or have a large number of visitors. Thanks heaps.

The last data we seem to have on Wikipedia can be found here, but this is over two years old - Wikimedia hasn't has the stats accessible for some time. However, this might be interesting for you, on a global web perspective: Usage share of web browsers. -- Mithent 13:36, 25 April 2006 (UTC)

I have a website [[17]] that uses a free counter by sitemeter.com. An example of statistics it generates from hits from my page are here [[18]]. - Cybergoth 21:48, 25 April 2006 (UTC)

Thanks Cybergoth, that's exactly what I'm after. Didn't realise visitors could see other webcounters stats, very handy. Bladerunner is in my top 3 films, although I haven't ever seen The Directors Cut, never will, think it will ruin my enjoyment of the film. 218.101.92.181 22:36, 25 April 2006 (UTC)

I have a tracker on my site from eXtreme Tracking, but I'm pretty sure my results are skewed due to small sample size and a selected population [geeks mostly :P]. You can see it here though. — Ilyanep (Talk) 23:27, 25 April 2006 (UTC)

I never knew that you could view site stats for another site, now I know that you can seek out (ie google) specific sites running extreme tracking (high levels of resolution) and see what sort of bias the site is getting. Yes lynanep, you do seem to have a geek bias, Linux users are about 4 times the proportion at your site than another site which is a blog about someone's thoughts. I was in a round about way wanting to know Linux market share (of web browsers) and the other site gives 0.65%. That means the only way is up.218.101.92.181 01:08, 26 April 2006 (UTC)

Bohrs radius in Plancks units.

Dears,

In line 34 of the sub-article "Plancks units and the invariant scaling of nature" of the main-article of "Plancks units" is after the normal equation of Bohrs radius used in NIST's CODATA and Wikipedia article about Bohrs radius an other equation in Plancks units namely:

a0 = mp.lp / (me.alpha)

whereby mp and lp are Plancks mass and length, me is the electron mass and alpha is 1/137.

My question is where does this equation come from and what is its derivation from the "normal" equation?

Boy Boer Breda the Netherlands

It's a simple set of substitutions. Starting from the Bohr radius $a_{0}={4\pi \epsilon _{0}\hbar ^{2} \over m_{e}e^{2}}$, we substitute in the fine structure constant $\alpha ={e^{2} \over 4\pi \hbar c\epsilon _{0}}$ to get $a_{0}={\hbar \over m_{e}c\alpha }$. Now, from the definitions of the Planck units $m_{P}={\sqrt {\hbar c \over G}}$ and $l_{P}={\sqrt {\hbar G \over c^{3}}}$ we get $m_{P}l_{P}={\sqrt {\hbar c \over G}}{\sqrt {\hbar G \over c^{3}}}={\sqrt {\hbar ^{2} \over c^{2}}}={\hbar \over c}$, which we substitute in to get $a_{0}={m_{P}l_{P} \over m_{e}\alpha }$ as you wanted. --Bth 14:37, 25 April 2006 (UTC), still not logged in

Ah, you beat me to it. Here's the same in Gauss units: $a_{0}={\hbar ^{2} \over m_{e}e^{2}}={\hbar \over m_{e}c}\times {\hbar c \over e^{2}}={\hbar \over m_{e}c\alpha }={m_{p}l_{p} \over m_{e}\alpha }$ Conscious 14:48, 25 April 2006 (UTC)

I have to say, I'm rather dubious about the claim in the Planck units article that this definition of $a_{0}$ is somehow fundamental, dimensionless, etc. -- the mass of the electron still sneaks in as a parameter, which isn't a combination of the five constants used as the basis of the system. Indeed, the equation explicitly uses the mass $m_{P}$ which is such a combination. --Bth 07:15, 26 April 2006 (UTC)

Electron acceptors for photosystems

Okay, I give up on trying to find this. Does anyone know if potassium ferricyanide is an electron acceptor for photosystems I and II, or only photosystem I? I believe that phenyl quinone is an acceptor for only photosystem II, though I could be wrong. Thanks in advance, if anyone can tell me! -- Mithent 13:54, 25 April 2006 (UTC)

I'm not sure what you're asking? If K3Fe(CN)6 can oxidize PS I/II? That would depend entirely on the redox state of the enzyme. There's plenty of experimental data on the redox potentials of PS I and II out there. --BluePlatypus 20:25, 25 April 2006 (UTC)

Calculating escape velocity - simpler method

In Y.Perelman's book 'physics for entertainment, he shows a much simpler way of calculating the escape velocity. It goes somewhat like this:

Stand on a hill of height say h metres. Throw a ball horizontally with a velocity v. The ball will fall towards earth. In 1 second, the ball would have fallen 4.9 meters [s=ut+(1/2)at^2]. If it is still h metres from the surface of earth (i.e. if it has fallen just enough to follow the curvature of earth), then v is the escape velocity.

I don't remember the exact argument and I am not able to derive it. I try and end up with a velocity of about 7.9 km/sec. Can anybody tell me where I am going wrong ? Do you know how he derives it ? Wikicheng 19:41, 25 April 2006 (UTC)

It sounds like that v is actually the circular-orbit velocity, not the escape velocity. As you've discovered, the two differ by a factor of sqrt(2). But to order of magnitude, an estimate of one is an estimate of the other. Melchoir 19:49, 25 April 2006 (UTC)

Also, for good accuracy you'll need to consider an infinitessimal time instead of "1 second", because that standard gravitational acceleration expression applies at finite time only when the velocities are small (so the orbit is effectively parabolic). --Tardis 19:51, 25 April 2006 (UTC)

Even if I use the time of 0.1 sec, I still get about 7.9 km/s. Looks like Melchoir's is right. 7.9*sqrt(2)=11.2 approx. Anyone who has read this in the above mentioned book? -- Wikicheng 20:12, 25 April 2006 (UTC)

Black hole horizon problems

I get the feeling that these are a common misunderstanding-driven question, but oh well.

1. Objects falling into a black hole will redshift out of visibility, and appear to slow to a stop as they approach the event horizon. If it takes an infinite amount of time (as viewed from far away) for anything to actually fall in, how is the black hole ever observed to grow (or even to really form, for that matter)?
2. Similarly, if I recall correctly, an object falling into a black hole will have its entire rest mass released as lost gravitational potential energy. Since rest mass is invariant, shouldn't the object be able to observe its own energy loss -- down, even, to 0 energy at the event horizon?
3. I saw recently (at photon sphere) that the circular orbital velocity at 1.5 radii is c; obviously the escape velocity is less than c there. So is it yet another GR revelation that with sufficiently intense gravity, the ratio of orbital velocity to escape velocity crosses 1?

GR is really too much; thanks for any clarification. --Tardis 20:08, 25 April 2006 (UTC)

For #3, isn't the escape velocity always less than any orbital velocity? —Keenan Pepper 20:54, 25 April 2006 (UTC)

Never mind me, I don't know what I'm talking about. —Keenan Pepper 21:02, 25 April 2006 (UTC)

Point 3 is really strange; I'd like to hear about that too. That must mean that (differently from the Newtonian case) the speed required to escape to infinity from near a black hole depends on direction. Which of course in the extreme case is obvious; if your perinigricon is below the event horizon, you ain't coming out.

What happens when perinigricon is near the event horizon, but above it? Are you accelerated to relativistic speeds? Do you lose significant energy to gravitational radiation, which might drop you below the event horizon on a trajectory that you thought was safe, if you hadn't taken that energy loss into account? --Trovatore 22:36, 25 April 2006 (UTC)

The physics outside a black hole are actually qualitatively not too different from the Newtonian case. There's still a conserved energy and angular momentum, and you can construct a one-dimensional potential that describes the radial motion of a test particle. The major difference is that this potential no longer has an infinite centrifugal barrier at r=0; instead it goes to negative infinity at r=2. (G=M=c=1) If the particle has an angular momentum greater than sqrt(12), the potential has a maximum somewhere between r=3 and r=6.

So no particle can escape with a peringricon less than r=3, which is apparently called the photon sphere. If you cross that photon sphere in the wrong direction, you're not coming out unless you light the fires. (And, of course, if you cross r=2 you're not coming out no matter what.) Melchoir 23:24, 25 April 2006 (UTC)

A more qualitative way of putting this is, "closer than the photon sphere, moving tangentially around the hole pushes you in, instead of out". You get very interesting optical effects too, due to the way light rays curve (the black hole looks like it takes up more than half the sky, with your view of the universe looking like a ball). --Christopher Thomas 21:46, 26 April 2006 (UTC)

As to the first two points, my extremely limited understanding is as follows:

1) We need a consistent definition of "fall in" here, I think. Crossing the event horizon counts, as far as I can see. As such, when something hits it, even if it takes an infinite time for us to observe the falling-in, it's already part of the mass of the black hole from the POV of the gravitational effects of the hole. AIUI, if it weren't for the infinite redshift part, a black hole would maintain the appearance of the last sphere of star material to cross into it during formation indefinitely. (But of course we've never actually observed any of this directly.)

I had thought of this explanation; the problem I have with it is that the black hole could then become asymmetric if, say, everything were to fall in on one side. That seems to violate the no hair theorem. --Tardis 15:47, 26 April 2006 (UTC)

2) This is one of those things that boils down to "the far-away and falling-in viewpoints see the same physics from very different perspectives". IIRC, it's been shown that for a black hole with minimal tidal forces (eg the supermassive ones in galactic cores) the observer crossing into the black hole barely notices the point of crossing the event horizon, so it seems they wouldn't get to notice their energy dropping to zero. However, they are now in a situation where all their possible worldlines contain a singularity in the future. But from the perspective of an external observer, what happens to them is forever inaccessible, shrouded by the event horizon, and so their mass has just become part of that of the black hole.

Most of that probably makes no sense, and anything that does make sense is probably wrong. --Bth 07:35, 26 April 2006 (UTC)

Physics of cutting

It says on the article on cutting, that an object can be cut with an appropriately hard tool with such a force, that the resultant stress exceeds the strength of the material in question - "The simplest applicable equation is stress = force/area".

Is it possible to arrive at a lower limit for the said area? I.e. to the point, where you are cutting just one atom wide? (and at arbitary length)

One could use the equation stated above to calculate the minimum energy requirements to cut through an object, supposing that you could use an impossibly sharp tool. In such a case, would there be other factors to consider, in addition to strength of the material and the area being cut?

This is my curiosity working again. Thanks for any responses. Santtus 20:58, 25 April 2006 (UTC)

Material properties such as strength are based in continuum mechanics, and don't apply on length scales not much larger than atoms. Moreover, it's very hard to define an area of contact when the edge is essentially one-dimensional, so the concepts of pressure and stress are not very applicable at all. Still, it would be possible to cut with a monolayer, although the knife would be quickly blunted by abrasion even if it were harder than the substrate -- one line of atoms cannot have the strength (hardness) associated with the bulk material. If the knife survived, it would indeed require very little force to make the cut. The difficulty might be expected to depend on whether one was cutting "between" atoms or "through" them with an edge that small, but the amount of energy required to shift and/or compress the material by half a bond length would probably be negligible compared to the energy required to break the bond. --Tardis 21:55, 25 April 2006 (UTC)

Thanks! So I'll be looking at bond energy and similar concepts, maybe measured in J/mol, or something like that. I'll look around. With few other numbers I can convert it into J/m^2 of cross section of area cut with the "perfect knife". I got suddenly interested of how far the current technology is from the "perfect" in that area, and I wanted to calculate that myself. Maybe I'll get a somewhat accurate estimate now. Santtus 00:15, 26 April 2006 (UTC)

And then you can get to work on a prototype of those laser whips they had in Johnny Mnemonic.  freshgavinΓΛĿЌ  05:00, 26 April 2006 (UTC)

Remember that a lot of the effort involved in cutting, say, cheese is friction between the substrate and the sides of the knife. This is one reason (along with uniformity of slice thickness) why some cheese slicers use wires, and it might affect your judgment of what counts as a "perfect knife". --Tardis 16:14, 26 April 2006 (UTC)

Can electricity be converted to kinetic energy??

I heard that electromagnetic energy can be converted into kinetic energy and move things around. If this is true how come background Em from things like powercables and TVS etc dont hit us all throughout the day?

Jonothan pritchard 23:00

The best way to convert electricity into kinetic energy is probably with an electric motor. Johntex\^talk 22:03, 25 April 2006 (UTC)

If you are asking why the EM energy emitted by power cables and TVs don't move anything, it is just that the waves emitted are too weak to move anything. But they do hit us. Powerful EM waves inside Microwave ovens can heat things up. Haven't you heard the argument that EM waves emitted by mobile phones are dangerous ? Being in the vicinity of high tension power cables for a long time is supposedly dangerous too --Wikicheng 22:43, 25 April 2006 (UTC)

Also take into account that most of the EM waves (sunlight/starlight/space radiation) are slamming down on you from above at about 299,792,458m/s. By comparison, very little comes from earth-bound items (unless you happen to be near a nuclear explosion). I'll never fully understand why physicists are absolutely certain that wave after wave of billions of electromagnetic particles slamming into you every millisecond of the day has absolutely no effect on your momentum. It seems logical that the high excess of EM waves coming from above would result in an overall momentum downward. --Kainaw ^(talk) 23:23, 25 April 2006 (UTC)

Actually, it's closer to 299,702,547m/s, unless you live in a vacuum bubble. Coincidentally, radiation from earth bound sources also strikes you at the same speed. Hm....? When it comes to sunlight, personally, I'd be most concerned at sunrise... perhaps that's why I stumble so much when I wake up early compared to later in the day. Andrewjuren(talk) 23:41, 25 April 2006 (UTC)

Actually, I do live a vacuum bubble, void of facts, statistics, and responsibility. That is why it is so easy to answer all the questions here. Regardless, my point was the quantity of EM coming from above compared to the quantity of EM coming from Earth. Everything I've read has claimed that even in the dead of night, the EM from Earth is insignificant compared to the EM coming from above. That did just spark a memory - is the Earth bright or dark? Most think that it has a bright side and a dark side - but that is because we only see visible light. With all our radios, televisions, cell phones... even in the dark we emit a hell of a lot of EM waves. So, for a radio-seeing being, it would be rather bright all the time. Of course, that has absolutely nothing to do with this question. --Kainaw ^(talk) 23:47, 25 April 2006 (UTC)

Not to mention the infrared energy that is given off naturally.  freshgavinΓΛĿЌ  04:52, 26 April 2006 (UTC)

See light pressure: sunlight on something facing directly into it is 4.6 μPa. So (being very generous with the size of the person and very conservative with their mass) there'd be something like 10 billionths of your weight added onto you while, say, sunbathing at noon. Entirely irrelevant, regardless of the direction it's applied. --Tardis 13:46, 26 April 2006 (UTC)

Synthesizer how-to

I have just downloaded a soft synth. Can anyone recommend me a good source of information of using (general) soft synthesizers? Thanks.

See our article on Software synthesizers. -- Andrewjuren(talk) 00:16, 26 April 2006 (UTC)

Soft synths are standardized so as to be supported by the largest number of programs possible. If you're running Windows, the soft synth is probably a VSTi, Macs are usually audiounits. Most programs either want you to put the softsynth file in their plugin folder, or you can specify a directory or set of directories to scan for soft synths. The software one would use soft synths with is called a Music sequencer. So the sequencer sends the data like note, duration, velocity and tons of other midi-like data to the soft synth, which returns audio. FL Studio is one of the most powerful, and one of my favorite sequencers. TheDapperDan 02:22, 26 April 2006 (UTC)

Try Musical Keys --Chris 02:26, 26 April 2006 (UTC)

Physics Textbook

Hi, my physics teacher mentioned a textbook a while back but I can't remember the name (something and Johnson's) that he recommended. It's probably a university level one since I'm in AP, if anyone knows what I'm talking about or has info on any good textbooks it be great. thanks 23:17, 25 April 2006 (UTC)

Hm, try here. Andrewjuren(talk) 00:14, 26 April 2006 (UTC)

Mac OS X

How easy is it to learn the Mac interface for a fairly advanced Windows User?

I'm asking because I want to get the Macbook pro when Mac OS 10.5 comes out, so that I can get boot camp and boot both Windows and Mac OS on the same computer [which would be mega-awesome considering some things you can do so much easier with a mac and because their hardware is better manufactured in my opinion. Plus, I like their user interfact. The only reason I never got a Mac was because they used to be very incompatable].

Also, what are other people's opinions of the Macbook Pro? Would it maybe just be better to skip this and get a good laptop when Vista comes out? — Ilyanep (Talk) 23:25, 25 April 2006 (UTC)

• As for the interface question: it's not very hard. Mac OS X is pretty easy to use and in many ways is similar to Windows XP. If you use it for a few days you'll get the hang of it. I siwtch between the two regularly without much confusion (except that for certain things, such as non-English characters, Mac OS X is a million times easier). --Fastfission 23:35, 25 April 2006 (UTC)

Max OS is similar to Linux desktops (KDE/Gnome) which are similar to Windows. Everyone steals the good ideas from everyone else. However, your idea that dual-booting a computer would be "mega-awesome" is flawed. Consider this: You are in Mac and you need to run a Windows program. You must reboot. You are then in Windows and you need to run a Mac program. You must reboot. It is far better to have some sort of embedded system. A popular one is VMWare (install Windows inside of Mac). Since I have plenty of computers at my disposal, I have a Win2003 box sitting in a corner and I rdesktop it when I need Windows. --Kainaw ^(talk) 23:50, 25 April 2006 (UTC)

I don't see myself switching between apps very often. On a computer, I'm usually either in game/goof off mode [Windows] or office/internet/homework mode [Mac]. Most design would somehow continue going on on Windows [as my copies of Photoshop, Flash, etc. are all Windows], and some things might become Mac-only [calendar management through iCal and GCal, etc.] If I were someone who made frequent use of both at the same time, I'd agree with you.

An annoyance I might see is having to configure wireless networking twice. But c'est la vide. Thanks for the answers. — Ilyanep (Talk) 23:54, 25 April 2006 (UTC)

Mac OS X is probably the easiest OS to learn, and it ripens the more you explore. There are a lot more applications you can download than you think. Boot Camp is better than nothing, and I think they will soon be able to have you switch between Windows and Mac OS X like application switching, or user switching. Usually I just want to see what is in the exe file, or something like that. If you get Apple Pages you can view .docs well, and with Apple Keynote, you see .ppts well. -- User:Mac_Davis 00:13, 26 April 2006 (UTC)

That's cool. I'll probably get iWork (Pages + Keynote) because it seems useful (looks like very nice presentations and documents there) -- although probably not Office (I can just use oo.o if i ever need a bread and butter office). All the rest will probably be freeware and downloaded, because I don't have money to buy a $2.5k laptop and then rebuy my expensive library of software :P which is why having Windows as a fallback is very nice (plus games).

I'd love to see a fast switch between OSes. And hopefully I can learn Mac OS X quickly, because I'm sure I'd feel quite set back after being an advanced user of Windows (been using it since 1994, as a 3-year-old). — Ilyanep (Talk) 01:19, 26 April 2006 (UTC)

See [19]. Parallels lets you run WIndows within the Mac OS, so you have both running simultaneously. It's free in beta, will be about $50 when it is commercially released [20] - 05:39, 26 April 2006 (UTC)

The thing is that you get a performance hit because you're running a windows app on top of windows dlls on top of mac os dlls. — Ilyanep (Talk) 12:07, 26 April 2006 (UTC)

Another question: If I have a Windows XP disc but it's an original XP [no SP2] disc, will it work with Boot Camp? If not, is there a way I can get an XP/SP2 disc from Microsoft? Perferably from the internet for free. — Ilyanep (Talk) 01:32, 26 April 2006 (UTC)

You should be able to download SP2 from Windows Update for free. The issue here is that your copy of Windows XP was probably authorised to run on your existing PC only. You'll have to ring Microsoft and arrange for the authorisation to be cancelled so you can authorise your Mac to run it. --Canley 03:17, 26 April 2006 (UTC)

In fact, bundled copies of Windows cannot be moved to another computer. This is part of the deal: in return for being a fraction of the retail price, they go to landfill with the computer. If of course the spare Windows XP disk was a retail copy, never installed, that doesn't apply, so I don't want to jump to conclusions. Notinasnaid 11:29, 26 April 2006 (UTC)

Oh no no no, it's a different retail disc copy of Windows XP that has long since been removed from the original computer. I also found how to slipstream SP2 onto a disc along with XP — Ilyanep (Talk) 12:05, 26 April 2006 (UTC)

April 26

For you Physics People

Question: When you are running and want to stop quicikly, must decelerate quickly. a) What is the origin of the force that causes you to stop? b) Estimate the maximum rate of deceleration of a person running at top speed to come to rest.

Does anyone know what they are asking for in part A? I don't quite get it, I mean I understand the question but I'm having a hard time visualizing how this would work. Any help would be appreciated thanks.

01:06, 26 April 2006 (UTC)

• The force is mostly friction between your feet and the ground, although there is some small contribution from air resistance as well, I suppose. (ESkog)^(Talk) 01:07, 26 April 2006 (UTC)
• Unless you hit a wall, in which case it's more of a normal force. Melchoir 02:04, 26 April 2006 (UTC)

To help you visualize the answer, imagine yourself running top speed, and then imagine what you would do to try to stop yourself. Most... humans extend one of their feet (most likely right foot for righties) and slam it down putting a lot of pressure on the one leg. By slamming your foot down, you are transferring your kinetic energy into the earth (the same energy transfers when objects crash), and since the earth is essentially stationary (relative to you running) and heavy enough so as not to be moved much by such a relatively small amount of energy, it will eventually take all of your previous kinetic energy and you will come to a stop.
If you stop by taking a few heavy steps as opposed to sliding your feet along the ground (like the way a hockey skater stops) then friction shouldn't be the major force, though there certainly is some friction force involved too.
Though the question may seem to be worded awkwardly, the origin of the force that stops you is the Earth.  freshgavinΓΛĿЌ  04:46, 26 April 2006 (UTC)

The major part is played by friction, even if you slam your foot down. If the surface on which you are running is smooth, no matter how hard you slam, you still will not be able to stop quickly. You are basically trying to prevent your body from continuing to move forward, by applying a backward force, using the friction between your feet and the earth. Even when the hockey player slides to a stop, he uses friction. If there was not friction, a moving body will not stop, unless it hits something else. I wouldn't be wrong in stating that all moving bodies in contact with other bodies slow down mainly due to friction between the bodies. (Ignoring other obvious cases like a direct collision and influence of other forces like gravity, magnetism etc) -- Wikicheng 13:49, 26 April 2006 (UTC)

About part b)- To calculate the rate of deceleration you'll have to use this formula: v=u-(a*t). Where, v=final velocity (in this case 0, beacuse the man is coming to a stop), u=initial velocity, -a=decelaration (+a for acceleration), t=time. If you know the amount of time taken by the man to stop and the initial velocity of the man, you can calculate the rate of deceleration (a). If you know the distance the man covered before he came to a stop, you can use the following formula: v^2=u^2-2aS, where S is the distance, v=0, if you know u(initial velocity) then you can find the rate of decelaration. (Note: ^ is to the power and * is multiplication sign).--DIGIwarez 15:54, 26 April 2006 (UTC)

Problem with Rope having a Mass

Suppose the cord is a heavy rope of mass 1.0 kg. Calculate the acceleration of each box and the tension at each end of the cord.

I can't for the life of me get the diagram on here, I've tried for the last half hour and I get "The file is corrupt or has an incorrect extension. Please check the file and upload again". I'll try describing with a bit of drawing on my part. I don't know how to do this because of the 1 kg rope, and most likely without it either. But we've never done any with ropes having a mass.

-----                             |-----|
m2=  |T2    T2    Cord  T1      T1|     |FP 40N(force of pull)
12kg |-->  <---++++++++--->    <--|m1=  |--->
     |       MC = 1.0kg           |10kg |
-----|                            |-----|
    

This is just the free body diagram:

The thing actually looks like:

    Rope
BOX------BOX 

in which the boxes are connected with the rope, and are in contact, unlike the top picture.

Thanks for any response.

02:53, 26 April 2006 (UTC)

I took the liberty of fixing your formatting. If you want preformatted text, you have to put a space at the beginning of each line. —Keenan Pepper 03:21, 26 April 2006 (UTC)

Thanks a lot for that. 03:34, 26 April 2006 (UTC)

Is there gravity? Are the boxes sliding around on an air table, or out in space, or is there friction from something...? Melchoir 03:42, 26 April 2006 (UTC)

The boxes are on the table and the question makes no mention of friction or gravity, but I believe it wouldn't need gravity because it's asking for movement along the x-axis, it shouldn't make a difference I would assume. 03:48, 26 April 2006 (UTC)

Well, it looks like all the elements accelerate equally. You can find that acceleration by considering the whole system as a single body with whatever total mass. Then determine, algebraically, the forces on all the elements of the system as a function of the tensions, and set those forces equal to the forces required to move them under Newton's second law.

By the way, if you don't like to deal with massive ropes, you can think of the rope itself as a box made of rope! You're only asked for the tension at either end, so conceptually there's a very short, massless rope that connects the rope-box to the box on the left, and another very short, massless rope that connects the rope-box to the box on the right. These new imaginary ropes will be under different tensions; you're asked to find them. Melchoir 04:01, 26 April 2006 (UTC)

So would you have a different answer for the tension if you didn't consider the rope a box itself? how would you do the question then? Thanks again. 04:11, 26 April 2006 (UTC)

No, the laws of physics are blind to the difference between boxes and ropes. (Well, they are up until you get to engineering mechanics.) A rope, like anything else with mass, accelerates if and only if a net force acts on it. I'm just saying that whatever conceptual model helps you solve the problem, go with it. Melchoir 04:21, 26 April 2006 (UTC)

Except that you can't push with a rope. (Or at least not normally. I once used a rope that had been soaked in water and frozen to push my physics teacher.) --Serie 22:35, 26 April 2006 (UTC)

A rope with mass means that there will be a linear tension distribution throughout the rope. Think of a heavy rope just hanging vertically. --Zeizmic 12:13, 26 April 2006 (UTC)

Assuming no friction and no stretching:

Once the ropes are fully extended (under tension), all the boxes and ropes will accelerate at the same rate. Call that 'a'. There will be tensions in the ropes too, marked in as T1 and T2. So we can calculate the forces on each object:

Forces on m1:

• m1 has forces of FP RIGHT and t1 LEFT. So the total force is (FP - T1) RIGHT
• It has mass m1 and the forces make it accelerate at 'a'.
• So F=ma ==> (FP - T1) = m1 x a

Forces on cord:

• cord has forces T1 RIGHT and T2 LEFT. So the total force is (T1 - T2) RIGHT
• It has mass MC and the forces make it accelerate at 'a'.
• So F=ma ==> (T1 - T2) = MC x a

Forces on m2:

• m2 has forces of T2 RIGHT only.
• It has mass m2 and the forces make it accelerate at 'a'.
• So F=ma ==> (T2) = m2 x a

Solving these equations:

• We have been TOLD that FP = 40, m1 = 10, MC = 1 and m2 = 12
• So if we substitute these numbers in, we get:

• (FP - T1) = m1 x a ==> (40 - T1) = 10 a
• (T1 - T2) = MC x a ==> (T1 - T2) = 1 a = a
• (T2) = m2 x a ==> T2 = 12 a

1. You now have 3 equations in 3 unknowns.
2. Rearrange the 1st and 3rd equations to get T1 and T2 in terms of 'a'
3. Substitute these into the 2nd equation to get an equation that has one unknown, 'a'.
4. Solve it to find 'a', the acceleration of the objects
5. Substitute again to find T1 and t2, the tension at each end of the cord.

FT2 (Talk) 00:10, 27 April 2006 (UTC)

Global Heating

In discussions of Global Warming, I am curious why there is so little focus on heat (as opposed to temperature). Temperature is important of course, but the transition of ice at 0°C to water at 0°C requires a lot of heat, implying that the polar ice caps, for example, are buffering the temperature rise. Then the question arises, if the total heat content of the planet is increasing, where will all that heat go when the ice has melted? Is this unimportant with the Greenhouse Effect? Is that heat just a very small part of the picture? Or is there enough ice that it's not an issue (yet)? Peter Grey 04:48, 26 April 2006 (UTC)

I have no idea. That said, I'm going to guess that measurements focus on temperature changes because they can be directly measured, while heat fluxes cannot. Behind the scenes, when one models climate change, I assume that latent heats and so forth are duly taken into account. And, to add the obligatory joke answer: because Global Heating sounds like an appliance manufacturer. Or maybe they lay gas pipelines? Who knows. Melchoir 05:02, 26 April 2006 (UTC)

Global warming is an issue because of expansion of the ocean. Think of it this way. An ocean might be 1000 m deep. If water expands 0.1%, that's 1 m. Goodbye Florida (joke). But yes, melting polar icecaps are heat sinks. But they only need to melted once and they're gone. I assume that the energy needed to melt them is relatively small. Lets do a small calculation on the back of a napkin. To Melt 1 million square kilometres with a depth of 100 m over 100 years. That's 10^6 x 10^6 x 100 = 10^14 cubic metres. 100 years = 10^2 x 4*10^2 x 2.5*10^1 x 4*10^3 = 4*2.5*4 (40) times 10^8 = 4*10^9 seconds. Dividing, 10^14 / 4*10^9 = 2.5*10^5 cubic metres a second. That's quite a bit. But that's only 2.5*10^5 / 10^12 = 2.5*10^-7 m = less than a micron per second. And no, I don't have a calculator on me as you guessed! 153.111.60.15 07:50, 26 April 2006 (UTC)

Without factoring in latent heats and heat capacities of various reactions and reservoirs, these numbers mean nothing. Melchoir 21:36, 26 April 2006 (UTC)

A related question, would this mean that once most of the Earth's ice has melted, we should expect the temperature to increase at a faster rate? Peter Grey 00:52, 27 April 2006 (UTC)

My theory on obesity and height

For a while now, I have come to the conclusion that shorter women are more likely to be obese/overweight than taller women. Of course, this can easily be proved/disproved if I had gender/age/height/weight for a random sample of people in a Western country with obesity issues. What are peoples thoughts? Does anyone have any actual research on this or stats? Thanks. BTW, I'm looking at, say age 30-40. 153.111.60.15 07:29, 26 April 2006 (UTC)

Maybe its just that taller people dont look overweight even if they are... as i understand being obese depends on the genetics and how much they exersice... not necessarily on the height of a person... (i am not completely sure about that last point) Jayant,17 Years, India • contribs 10:39, 26 April 2006 (UTC)

I think Jayant's point about perception is sound. A quick Google brings up two studies:

Height-Related Changes in Body Mass Index: A Reappraisal gives a slight positive correlation between body mass index (a popular measure of whether someone's overweight) and height for men (ie taller men are "fatter") and a slight negative correlation for women (which fits User:153's belief). That's for data from people coming out of the Israeli army just over the age of 20, so it may not be that similar to 30-40 year olds in other contexts.

These guys from FSU (warning: pdf doc) examine a wide range of populations and generally find a negative correlation for both men and women (again in line with the User:153's theory). But they use it to argue that a blanket application of BMI is therefore not a good way to determine whether someone's overweight, rather than that shorter women are more likely to be overweight.

Note that in both cases the correlation coefficients, while statistically significant, are small in absolute terms -- the effects are there, but they aren't all that large. --Bth 11:42, 26 April 2006 (UTC)

Turbine engineering

How is it possible to maintain a seal between the shaft of high pressure turbine and the chamber it is enclosed in?

Turbines are a complex bit of engineering. I know that we always have trouble with the monster turbines. I suggest you brush up on your Google skills. --Zeizmic 12:17, 26 April 2006 (UTC)

PVC substitutes

I am wondering what materials may be used in place of PVC in its main applications (Namely construction, housing, toys, cars and medical use). Thanks in advance. ...

Polyethylene and polypropylene for toys, cars, diapers and medical use I believe. I would imagine most types of relatively harmless polymers could be used for any of those categories. -Snpoj 11:37, 26 April 2006 (UTC)

Wrong question. The right question to ask is "Why is PVC used in so many applications despite its being so poorly suited to the purpose at hand?" The answer is that in the process of alkali electrolysis sodium hydroxide is the sought-after product. Chlorine is producted in equal amounts and is really an unwanted byproduct. Converting it into PVC is one way to dispose of what really is a waste product. Dr Zak 11:45, 26 April 2006 (UTC)

You could use pretty much anything non-toxic for toys. For medical use biocompatibility is of primary concern, common polymers used in hospitals (for IV tubes and the like) include polyethylene (PE) and silicone. In construction, I can't think of any alternatives that are used (particularly with a high volume area like construction, price is a mjor factor in choosing a material). There is lumber made from recycled plastics, but that doesn't replace a PVC application. Polymethylmethacrylate (PMMA) is a strong, fair enivronmentally material that is used for greenhouses and architecturally. The plastics used in cars include polyurethane (PU), polypropylene (PP), acrylonitrile butadiene styrene (ABS), polycarbonate (PC), and PVC. Generally, PU, PS, ABS, and PC are the most commonly subsituted polymers for PVC. --Chapuisat 14:42, 26 April 2006 (UTC)

I always think of something to add write after posting a reply. I should have mentioned that all polymers have advantages and drawbacks, many of the alternatives to PVC (such as ABS) also use hazardous chemicals. Polymer engineering hasn't always been the most environmentally friendly field, but over the last decade or so I think it has improved quite a bit. --Chapuisat 14:48, 26 April 2006 (UTC)

Leather and latex. Oh, constructions purposes. My bad. --Blowdart 17:39, 26 April 2006 (UTC)

Redirect From Incorrect Spelling?

Is it appropriate to make a redirect from for example, Pyramidine (incorrect spelling) to Pyrimidine? -Username132 (talk) 10:36, 26 April 2006 (UTC)

It usually is, yes, though someone's already done that one. This was more of a question for the help desk, though, since it's about editing Wikipedia rather than a specific question about science. -- Mithent 11:05, 26 April 2006 (UTC)

It usually is, yes, but somebody has already done so. Ask at the help desk next time, but how you do it is: #REDIRECT[[Page name you redirecting to]] -- Mac Davis] ⌇☢ ญƛ. 12:22, 26 April 2006 (UTC)

Did you guys plan that or something? --Chapuisat 13:40, 26 April 2006 (UTC)

Sorry, I did go to the help desk, and didn't realise I could post there. I just saw the humanities, science options etc. and thought I had no other choice. Btw, the somebody who did it was me, I just wanted to make sure I was doing the right thing. --Username132 (talk) 15:12, 26 April 2006 (UTC)

long term memory

characteristics of long term memory

1 The ability to receive and store information during observation. 2 The ability to trace and recall information stored in long term

 memory.

3 Like sensory storage, long term memory has a large capacity. 4 Long term memory is usually well organised. 5 It is a relatively permanent form of memory. 6 The information is sifted,coded and stored and thus form a

 components or part of all experience that can be remembered.

7 Information is rearranged when new material is added. 8 The process is not static, but dynamic. 9 Information obtained through any of the senses can be stored. 10 New meterial can be arranged meaningfully together with the old

  meterial.

11 Familar meterial or information is easier to process or arranged

  than unfamiliar material.

DESCRIBE AN EVENT OR WRITE A STORY (ROUGHLY 200 WORDS) ABOUT SOMETHING THAT YOU HEARD ABOUT OR EXPERIENCED YOURSELF ABOUT A YEAR AGO. NOW ANALYSE YOUR PIECE OF WRITING IN TERMS OF THE ELEVEN CHARACTERISTIC OF LONG-TERM MEMORY AND TRY TO DETERMINE THE DEGREE TO WHICH YOUR WRITING SATISFIES THOSE CRITERIA.

• Please read the instructions at the top of the page. This page is to ask questions, not to set assignments. I wonder what your short term memory is like...- 131.211.210.13 12:45, 26 April 2006 (UTC)
• Ok, I did that: I wrote a story of roughly 200 words, and analysed it. Thank you for the suggestion. Notinasnaid 14:16, 26 April 2006 (UTC)

can you tell me how to install windows XP in a newly brought system

Media:Example.ogg

Take your newly purchased copy of Windows XP (not one reused from an older computer, unless it was purchased retail), put it in the CD drive, and boot. The system will boot from the CD and install Windows XP after a few questions. Notinasnaid 14:14, 26 April 2006 (UTC)

If the computer is set-up to boot from CD, you will see "press any key to boot from CD"; you'll then have a window of a couple of seconds in which to press a key, so make sure you're paying attention. If you don't see this message on the screen, come back for more help. -Username132 (talk) 15:09, 26 April 2006 (UTC)

Virtual Memory

I've heard in the past that your virtual memory should be set to 1.5x your physical memory. I just upgraded from 512mb RAM to 1024mb RAM, but it doesn't look like my virtual memory went up. Can anyone with 512 or 1024 RAM let me know how their settings are in WinXP SP2? Thanks. --Chris 15:49, 26 April 2006 (UTC)

You can set your VM to whatever you want; so long as you don't find that you're running out (angry dialogs and crashing applications), you're fine. You don't get any benefit from having "extra". But for what it's worth, the system I'm currently using (though it's not Windows) happens to have approximately equal amounts physical and virtual: about 1GB each. If you have the hard drive space to spare, set it to 2GB or more if the system will let you, and then you won't worry about it. But if you want to conserve space, and haven't had any trouble, just leave it alone. --Tardis 16:19, 26 April 2006 (UTC)

This is known to be very poor advice, regularly criticized on IT forums. Read virtual memory to understand what VM does. Basically, your computer will use X amount of memory to work, the exact amount varying depending what you are doing. It uses all the RAM it can, the rest is made up using VM. So in fact the more physical memory you have, the less VM you need and vice versa!

As a rough rule of thumb, unless you're doing complex processing (video editing, photoshop etc), and given how cheap physical memory is today, I'd use this for a rule of thumb with Windows XP: as you have, use between 512 MB and 1024 MB of physical memory (not less than 256 MB), and then set virtual memory to use a set (fixed) size of around minimum 512 MB and maximum 1536 MB (if your hard drive allows it). The fixed size stops Windows having to extend the file quite so often. That should fix it up nicely.

If you do intense work on photoshop or video work (not just DIVX coding!), eg professionally, then get more RAM (1-2 GB is not uncommon) a fast modern dual core processor, a solid and stable motherboard (eg ASUS which I use and have never had a problem with) and a huge hard drive (Seagate's 'Barracuda' range currently offer the best price/quality/warranty/speed balance). FT2 (Talk) 19:58, 26 April 2006 (UTC)

Running a local server... issues

I'm using Mac OS X Tiger, and I'm running a personal web server (Apache) off of my local machine which I use while writing PHP. Normally this is fine -- I point the page to the local address (http://mycomputer.local/~myusername/) and it runs fine. However just today it has, without me changing the settings, redirected from mycomputer.local to the local IP that my university has assigned for my computer's internet access. In fact, if I type in the address as http://127.0.0.1/~myusername/ it will automatically substitude it with http://net-23295456.myuniversity.edu/~myusername/. Some of my scripts execute fine, despite this, but some give me a 404 error. What gives? --Fastfission 16:22, 26 April 2006 (UTC)

• The more I tinker with this... I think the latter "net-2323" bit still goes to my local computer. Yet it sometimes will, sometimes won't run a script. I haven't had this issue before. I've tried restarting the web server, restarting the computer, disconnecting and reconnecting it to the internet, using different browsers, resetting my cache, clearing the dynamic DNS, etc., to no respite. Argggg. --Fastfission 17:06, 26 April 2006 (UTC)

• Actually, now it's only failing whenever I try to open a new locally hosted script in a javascript window, and try to pass GET arguments to it in the URL. What the hell. If I don't try to pass arguments, it executes the script just fine. Why is my computer being such a pill? --Fastfission 17:13, 26 April 2006 (UTC)

What is the ServerName set to in apache? EricR 17:36, 26 April 2006 (UTC)

• Nevermind, I figured it out! Not a big deal, I was confused about something, please ignore. --Fastfission 01:30, 27 April 2006 (UTC)

Direct ancestor of Homo sapiens?

I'm trying to trace an approximate timeline between modern humans and the dawn of life. For example, who are the direct ancestors of Homo sapiens? Would it be erectus? And what is the ancestior of primates, e.g. the "protoprimate"? and then the ancestor of all mammals, before mammals branched out into all the different kinds we know today. And so on and so forth to the earliest known life forms from which presumably all life evolved. For example is Tiktaalik a possible ancestor of humans? Or a cynodont? etc. What's the most accurate line as we know it?--Sonjaaa 16:57, 26 April 2006 (UTC)

Well you can't think of lines as just being straight shots, first of all. They get all mixed up with themselves and look more like bushes than trees. Secondly, we don't have straight genealogies available anyhow. Anything could be a "possible" ancestor of humans if you are talking about as far back as Tiktaalik. Take a look at our evolution of homo sapiens article for an overview of what is known and what can be said about it. --Fastfission 17:04, 26 April 2006 (UTC)

Also look up Y-chromosomal Adam and Mitochondrial Eve, Most recent common ancestor, and Last universal ancestor. FT2 (Talk) 20:08, 26 April 2006 (UTC)

Also, a good article to get acquainted with some of the conceptual difficulties making sense of this sort of genetics is Troy Duster's "Deep Roots and Tangled Branches". --Fastfission 01:32, 27 April 2006 (UTC)

Who designed Monobook?

Who designed the Monobook skin, initially, for Wikipedia? We need this in relation to a media outlet's request. -- Zanimum 17:38, 26 April 2006 (UTC)

User:Gwicke. --James S. 18:06, 26 April 2006 (UTC)

But I believe he based the design (and may have used some of the collateral, such as images and styles) on a weblog skin (I'm afraid I forget which). -- Finlay McWalter | Talk 18:11, 26 April 2006 (UTC)

Are centipedes arachnids?

This spider book I'm reading mentiones that scorpions, mites, and centipedes are all arachnids. But according to Wikipedia, centipedes belong to the Subphylum Myriapoda, while arachnids belong to the Subphylum Chelicerata. Can someone explain this to me? Maybe scientists can't agree where centipedes belong? Jonathan ^talk File:Canada flag 300.png 17:44, 26 April 2006 (UTC)

Wikipedia's articles place Class Chelipoda (centipedes) in Subphylum Myriapoda, as do some other sources (try Googling "Myriapoda"), but I found a source placing them in Arachnida (Hawaii Biologial Survey). Another source ranked Myriapoda as a class, equal to Arachnida (Kendall Bioresearch Services). So it appears there's no firm consensus where they belong, but placing them in Arachnida seems outdated at best. --Ginkgo100 18:13, 26 April 2006 (UTC)

Wikibooks has a dichotomous key for arthopods, the place where centipedes and arachnids are thought to diverge. You can read it here. The key is based on morphological features (antennae, number of feet, etc.) which is popular among some biologists, while other prefer genetic sequence analysis or using other types of distiguishing features. That may be why there is not an agreement on the exact phylogenetic tree. You may also enjoy looking at the wikispecies entry on centipedes. --Andrewjuren(talk) 19:21, 26 April 2006 (UTC)

Different prongs on electrical plugs

The lamp on my desk has a plug with two flat parallel prongs. One of them is wider than the other, and I believe it to be a Type A Nema 1-15. see Domestic AC power plugs and sockets. My question is, why do the prongs differ from one another? In my youth common electrical plugs had prongs that were identical in shape. They carry alternating current, so what is going on electrically at the two prongs are the same, and one is not "hot" and the other "neutral" at least in any electrical sense, it seems to me. Electrons are moving alternately into and out of each prong during the cycles. I've taken graduate courses in E&M, but still wonder at this...--DonSiano 18:21, 26 April 2006 (UTC)

You are mostly correct. However, although the electricy is alternating current, one pole remains roughly neutral (relative to ground) while the other alternates on average 120V (relative to ground). Keep in mind that I am discribing the voltage of the plug relative to ground, not the current running though an appliance. -- Andrewjuren(talk) 18:54, 26 April 2006 (UTC)

I have 'unconsciously internalized' this from somewhere: Polarized plugs have a wide neutral prong and can only plug one way into a receptacle. In a properly wired lamp, the polarized plug ensures that the hot wire energizes the metal tab at the bottom of the socket, which is less exposed to fingers than is the threaded shell. --Zeizmic 19:46, 26 April 2006 (UTC)

Radishes

Really random but I need to know for my A2 Biology coursework, are radishes leguminous nitrogen fixing plants or non-leguminous nitrogen fixing plants? I have looked on this site and others and cannot find an answer! I would really appreciate it if you could get back to me asap on this as my coursework needs to be handed in shortly and I've nearly done the rest of the project!

Thank you for your assisstance!

Dee x x x

You should at least have looked at radish, legume and Nitrogen Fixation before asking us to do your homework. (though I think the answer to the question you posed is "no"). Malcolm Farmer 19:10, 26 April 2006 (UTC)

PCL6

I am trying to investigate the contents of packets being sent to an HP IP printer using PCLXL (now called PCL6). Upon viewing a packet capture of the data I find very little, if any, information that is readable/useful. I have a white paper on PCL6, but I find it to be less that helpful. If anyone could provide some insight on what steps to take to extract the print data please let me know. Ideally I would like to have some sort of break down of field sizes and possible values, but it looks to me like the data need to first be converted into some other format.

Below is an example of the data that goes across the network when printing a file. It is compiled from several packets and derived with the "Follow TCP Stream" functionality in Ethereal. I didn't include all the output to help keep it short. In addition, some data that could be used to identify me has been removed. If it would be helpful to have the full capture please let me know.

.%-12345X@PJL SET STRINGCODESET=UTF8 @PJL JOB NAME="Document" @PJL COMMENT "HP LaserJet 2420 PCL 6 (60.42.108.11); Microsoft Windows XP 5.1.2600.1; Unidrv 0.3.1296.4" @PJL COMMENT "Username: REMOVED; App Filename: Document; 4-21-2006" @PJL SET JOBATTR="JobAcct1=REMOVED" @PJL SET JOBATTR="JobAcct2=REMOVED" @PJL SET JOBATTR="JobAcct3=REMOVED" @PJL SET JOBATTR="JobAcct4=REMOVED" @PJL SET JOBATTR="JobAcct5=REMOVED" @PJL DMINFO ASCIIHEX="0400040101020D101001153230303630343231313532363133" @PJL SET USERNAME="REMOVED" @PJL SET DUPLEX=OFF @PJL SET ECONOMODE=OFF @PJL SET RET=MEDIUM @PJL SET RESOLUTION=600 @PJL SET BITSPERPIXEL=2 @PJL ENTER LANGUAGE=PCLXL ) HP-PCL XL;3;0;Comment Copyright(c) 1999 Microsoft Corporation .X.X...........A........H...(...&...LETTER.%C.d.d..*u....?...?.+w....j...-x...-|......Lk...,{....c....y...........B.....,{.....c........MS PCLXLFont 001..O.....P.........p.....P..GT...d.....P.........@... .`...P.`cvt .......l...0fpgm...........pgdir............head...... ....8maxp...... D... prep...... d.....0...P.0................&...............i.......i.....................i.....................D...|.......Z.....R.R...D......./...........W.~................... .".A.P.o...L.u.\.....7.L.n.p...X...................c.c.........-.\...........@.W.......r...]...g.....!.w.....M.....+.L.e.....|.C.............].h.....5.G.!.\.M.....-.x...........................,.I.............?.......).9.I.o.......#...o...2.@.z.....1.U.W.........~.~.....F.B................./.O.V.).o...r...,.1.1.d.i.........+.....................&....... ... .s.......C._...........a...^.m.........

And it goes on...

Thanks for your time. --Daniel

Get the source for ghostscript, it includes a PCL driver, study that and you can figure it out. Try printing a simpler document, like a single letter 'a', and see what gets sent over ethernet and see if you can figure out the translation. Try asking in the right newsgroup. See Printer Command Language and various links to documents attached thereunto. --GangofOne 18:59, 26 April 2006 (UTC)

What you are seeing there is a fairly simple PCL stream, or the start of one. After the setup commands, it begins to download a font, which will go on for quite a long time. The specification for this print language should have the information you need to break it down - but be sure it is exactly the right specification, as HP updated it regularly. Parsing the full range of PCL is hard work - I'm not sure what you are trying to achieve with this analysis? If how to write PCL, don't do it that way! Notinasnaid 20:20, 26 April 2006 (UTC)

Thank you for your input. Starting with the "specification" for PCL, this is actually my problem. I have been unable to locate any specifcation that would allow me to adequately parse through bytes and retrieve meaningful data. I don't need to parse ALL of the stream, just the data intended for printing. The end goal of the analysis is the extract data for input into another program. My goal is not to write PCL. As for sending a "simple" text document across the wire and view the traffic, this is it. Actually, this is it, or rather almost it. My first attempt was the word "hello" sent across all by itself. This stream was for a document reading "hellohellohello...." The data is obviously encoded in some format, I just don't know, and can't figure out exactly what it is.

I'd expect there's a good chance of seeing the "hello" somewhere down towards the very end, after the font downloads. PCL has the potential to be simple, unlike some other printer formats which simply take a binary bitmap. It is the ability to download fonts which makes simple printing possible: otherwise, the requirement to match a font would make it compulsory to print a page as a bitmap. Though some print methods will still turn out an entire page bitmap in PCL (e.g. GhostScript's PCL driver). Traditionally the format of PCL was something like

stream: [ plain text | escape sequence ] *
escape sequence: escape character , arbitrary characters, length defined by context

If the real question is: where is the latest PCL specification, the answer might be "HP keep it proprietary and only license it" ... and that would make sense because HP don't want the whole world to copy their printer technology. But that would be a guess. A good way to find people who might know is to post on the PCL article's talk page. But there is an encouraging find: in Usenet I found the comment "You can order the PCL specifications including PCL 6/XL from HP. But it can sometimes be a little problematic, as it seams not all sales people at HP know this ;) But it is possible, I succeded." Notinasnaid 07:09, 27 April 2006 (UTC)

Leaves in Georgia

In my Science class, our teacher gave us a project that is due May 10,2006. We have to find 15 different leaves, seal them in wax paper, give the accurate name and tree where found,etc... I needed help because the leaf examples have been located on your site in another part of a state and I need different leaves inside Covington Georgia. Area code:30016. I would greatly appreciate it if you guys can please locate some leaves in this area and send me a reply!

danielandtay@GA411.org

You could go to the library, check out one of the Peterson's guides or similar tree identification book, go to a forest preserve or large park, look up the trees in the book, and then do the picking, sealing, etc. Dismas|^(talk) 21:06, 26 April 2006 (UTC)

Let me point out that there are two ways to do this, either start with the leaves you found, then try to identify them, or start with a list of leaves in your area, then look for each. You might want to focus on leaves with highly distinctive shapes, like maple leaves, as they are easier to identify. Also, if you have a guide book with you when you pick the leaves, you can also check the tree height, bark, etc., against the descriptions in the guide. StuRat 21:51, 26 April 2006 (UTC)

library's for chumps. Do as Calvin did and sell the earth for alien leaves. -Snpoj 21:53, 26 April 2006 (UTC)

Solar Power Cars

Could a car whose surface area is covered in solar pannels produce enough electricity to run? If not, how efficent do the S. Pannels need to become before this can be possible? The current efficency rate is ~15% 199.201.168.100 21:13, 26 April 2006 (UTC)

Try Solar car. Melchoir 21:15, 26 April 2006 (UTC)

Short answer is, "never as well as a car with a gasoline engine". Even perfectly efficient solar panels give you 1 kW/m^2 under direct sunlight at high noon (or about 1.3 HP per square yard, for Americans reading this). So, an ordinary-sized car with perfect solar panels would give you somewhere around 10 horsepower under ideal conditions. Generally 100 horsepower is considered the minimum for an ordinary car. --Christopher Thomas 21:53, 26 April 2006 (UTC)

If a tree falls in the woods, does it make a sound?

Why is this a popular question? Clearly sound waves are produced, so it becomes nothing more than a petty arguement over the definion of sound. Sort of like if "If all humans became extinct, would puppies still be 'cute'?" 199.201.168.100 21:13, 26 April 2006 (UTC)

It's said to be a koan (although I'm not sure where it comes from; it's not in The Gateless Gate). The point is not to have a petty argument about semantics, the point is to think deeply about the role of the observer in all forms of experience and perhaps get closer to enlightenment. —Keenan Pepper 21:21, 26 April 2006 (UTC)

I agree with Keenan. This is not a purely scientific question. But, some might argue it's relevance to Observer effect. Like, if you don't look at an electron, is it really there? Or for that matter, is it ever really anywhere? --Andrewjuren(talk) 21:50, 26 April 2006 (UTC)

"Some" might only be me. --Andrewjuren(talk) 21:50, 26 April 2006 (UTC)

Do Your Own (Dharmic) Homework! Snide comments on the RD from people like me are no substitute for proper meditation on koans and the meaning of 'mu'. --Sam Pointon United FC 21:27, 26 April 2006 (UTC)

Today we have a simple answer. Once upon a time, people didn't know as much about physics, and they didn't actually know the answer, and it would require a lot more thinking. Peter Grey 23:34, 26 April 2006 (UTC)

It is simple if sound is clearly defined; under the primary definitions, the answer appears to be no. — Knowledge Seeker দ 04:51, 27 April 2006 (UTC)

See Mysticism for more. This is a famous "pointing out" exercise. Its intention is not to exercise the intellect, but to throw a question at it that helps it think "outside the box". The question was never intended literally as a physics quiz. FT2 (Talk) 00:16, 27 April 2006 (UTC)

This long predates western knowledge of zen and it is not mystical. It is more related to the philosophical arguments (after Berkeley) about whether things exist apart from our perception of them. I suspect you could find some 19th century English or American usage of this particular version of it. alteripse 00:55, 27 April 2006 (UTC)

A few years ago in a philosophy class, I heard an interesting answer: It does not, because "sound" is defined to be something like "that which we can hear." Personally, I prefer a less biased definition, though. Ardric47 02:48, 27 April 2006 (UTC)

Sound is defined as the disturbance of mechanical energy that propagates through matter as a wave. If the question is taken from a purely scientific point of view, the answer is a resounding yes.  freshgavinΓΛĿЌ  04:25, 27 April 2006 (UTC) resounding. *wink*

That is one definition, yes, although not the primary definition either at Wiktionary or at Merriam-Webster. Following the primary definitions (auditory perceptions or sensations), then quite clearly the tree does not make a sound if no one is around to perceive it. It depends how you wish to define sound. — Knowledge Seeker দ 04:51, 27 April 2006 (UTC)

And that pun is resoundingly lame :) 12.183.203.184 04:31, 27 April 2006 (UTC)

The way I typically interpret this riddle is that it's something that simply can't be proven one way or another. While you can talk about stuff like defining sound, etc., the bottom line is that you can't prove whether a tree makes a sound if no one is around to hear it because any proof would involve someone actually being around to hear it. Obviously as scientists we know that it must make a sound (or not, depending on how you define sound), but this is simply an argument that's impossible to win against a skeptic. EWS23 | (Leave me a message!) 05:00, 27 April 2006 (UTC)

No, the definition of sound is in fact the important thing. Proving that the tree did the thing with the air vibrating that people can usually hear if they're close by is easy, at least as a thought experiment: the sound decays into heat as it's absorbed by the forest. In other words, while we may meaningfully argue that perception is an important property of the world and helps define it, no one seriously argues that the lack of observers actually affects the physical occurrence (including what anyone present would have labelled as sound) except for certain real but wholly unrelated issues of measurement in quantum mechanics.

Look at archaeology for a science that never involves "being there to see it"; did the Egyptians really build the Pyramids, or do we just suppose that because big rocks are arranged in neat shapes, had we been there, we might have seen someone working on it? It's silly to be skeptical about things that obviously did in fact happen, even if no one saw them. After all, if someone shows up and points out that they in fact cut the tree down and quite clearly haerd it fall, why not label it as hearsay and continue to refuse the sound, and everything else you're not currently watching, existence? And then keep going and posit that you may in fact be only imagining that the world exists... This too has been done, but the original question presupposes that trees do in fact fall in forests, so it's wrongheaded to apply the unanswerable questions in the philosophy of existence itself to the question. --Tardis 07:27, 27 April 2006 (UTC)

Well, there is a school of thought that the only thing you can be absolutely sure of is cogito ergo sum, and that anything else could simply just be the the work of some evil scientist or something like The Matrix. That wasn't really where I was going with my original post (though heading toward those lines, I suppose); I was just saying that if you neglect the cogito ergo sum argument, there are quite a few things that you can physically prove to a casual observer, but the tree falling in the forest example isn't one of them. (I guess what I'm going for here is that I was taking more of a philosophical interpretation of the famous riddle than a scientific one.) EWS23 | (Leave me a message!) 08:34, 27 April 2006 (UTC)

Last Question for today

If all humans suddenly became extinct, would puppies still be cute? 199.201.168.100 21:13, 26 April 2006 (UTC)

No, but the reason is one that you wouldn't have guessed. I happen to operate a dead man's switch that, in the event of my own incapacitation, will release an army of robot laser cats to obliterate the world puppy population. They know why. Melchoir 21:29, 26 April 2006 (UTC)

I presume there would be some time between your death, and when the switch activates, as well as some time between the switch's activation and the time the cats finish their work. Durring this time, would the puppies be cute? 12.183.203.184 22:57, 26 April 2006 (UTC

No, because I have an army of neutrino triggered nanorobots that hop like fleas from dog to dog, and which are transmitted by birth. So every puppy has one. At the time I die (and I will die no later than the last human), a neutrino-modulated signal will be released which before I even draw my last breath will activate all nanorobots and almost immediately turning every puppy on the planet into grey goo. During this process I can assure you that a hundred million rapidly-melting puppies in crisis will be anything but cute. FT2 (Talk) 00:22, 27 April 2006 (UTC)

Excellent, now my army is free to pursue other ends... Melchoir 00:28, 27 April 2006 (UTC)

Adult dogs react emotionally to puppies. If that falls under your definition of 'cute', then they're still cute. If 'cute' is only a cultural concept of humans, then it ceases to have meaning if humans become extinct. Unless whoever made us extinct thinks puppies are cute. The cuteness of kittens, of course, is objective fact. Peter Grey 00:34, 27 April 2006 (UTC)

The answer is undefined. Humans won't be confirmed extinct until the World Conservation Union deems them to be, and I have a feeling that the leftover puppies won't be willing to do all the paperwork.  freshgavinΓΛĿЌ  04:21, 27 April 2006 (UTC)

Alternate Launching techniques

This was a type of launch platform used in an episode of Star Trek: Enterprise. Would this work in today's times, and if not why not.

File:Enterprise first flight.png

Chuck 22:05, 26 April 2006 (UTC)

What is it? How does it operate? We can't really tell these things from a picture. Isopropyl 22:43, 26 April 2006 (UTC)

Without seeing it in action, I can't be sure, but that looks like a maglev/linear motor track with a ski jump curve on the end. It's a pretty popular alternative launch system in science fiction: accelerate the spacecraft down the ramp until it reaches orbital velocity, then use the ski jump curve to turn a little bit of that velocity into altitude. The spacecraft then fires its engine once it reaches apogee halfway around the world to circularize the orbit. It would be possible to build one today, but it would be extremely expensive.

As a bit of science-fiction trivia, Mount Wilson is a popular place to put this sort of launcher. --Serie 22:58, 26 April 2006 (UTC)

Is this on Earth? It's effectiveness would depend on the local gravity and atmospheric density. As I understand it, building one is technically feasible, but you also have to consider whether it's economically feasible, given that the actual designs of the linear and curved sections will be limited by the how much acceleration whatever you're launching can survive. Peter Grey 00:24, 27 April 2006 (UTC)

Theres actually some interwting science about these kind of things. First, read up on escape velocity. Basically, if we could ignore the atmosphere, then any object travelling under escape velocity will remain on (or return to) earth, and any object over escape velocity will either escape from earth (if pointing above the horizon) or hit earth (if pointing down). It does not matter if the object is pointing up, at an angle, or horizontal. If you ignore atmospheric effects, the ONLY question is, if it is pointing above the horizon (nothing in the way!) and above escape velocity, it escapes, otherwise it returns or crashes to earth. Its that simple. Direction has nothing to do with it. Its purely the potential energy needed to escape earth, and the kinetic energy given to it by escape velocity, and which is bigger than the other.

HOWEVER... if you take into account the atmosphere, the atmosphere applies friction and air resistance to moving objects, strongly slowing them down. Imagine walking into a strong wind. The atmosphere is denser near the ground. So it pays to get above the lower atmosphere as fast as possible, to minimize the loss of energy. A horizontal track would work, but would have to launch a vehicle faster to allow for this loss, than a vertical or tilted take-off. And so yes, this design is feasible. Robert Heinlein's book The Moon is a Harsh Mistress describes one of these and some of the science. FT2 (Talk) 00:33, 27 April 2006 (UTC)

Wow...great answers. Thanks everyone! --Chuck 02:07, 27 April 2006 (UTC)

You often hear about jump launches like this as being good solutions for launching RAMJETs or other high-speed craft that can't operate properly at low speed. After accelerating down a long maglev (or similar) track (a very wide circle track might work even better) the craft launches off the final ramp and the engines engage. The main problem with this is that if the track isn't circular, you will almost certainly be subject to very high g-forces from acceleration, and engaging the engines after flying off a ramp probably isn't the most comfortable experience either.  freshgavinΓΛĿЌ  04:16, 27 April 2006 (UTC)

It's the acceleration on the tightly curved ramp at the end that would keep me from getting on this thing. If the device were launching objects without their own propulsion into orbit, and had them moving at escape velocity (many thousand mph) by the time they reach the curve, there would be preposterous force on both the track and projectile, whether the curvature is circular or not. The only way to practically build something like this is to lay the entire track (or at least the highest-speed portions) on a straight line. As noted above, even a horizontal track would work, provided there are no mountains in the way. ×Meegs 06:30, 27 April 2006 (UTC)

baseball problem

A 0.145kg baseball travellng at 30m/s strikes the cathcesr mitt bringing the ball to a stop. The glove recoils back 11cm. What is the average force applied by the ball on the glove?

Confused since the distance (11cm) is after the ball is at rest. then I don't enough info to do it, but yeah if someone could show me thanks. C-c-c-c 22:44, 26 April 2006 (UTC)

F = ma

A = 30/t

D = 11 = VT + .5AT^2

Two equations, two unknowns. Solve for F&T. 12.183.203.184 22:53, 26 April 2006 (UTC)

To address the fundamental problem, try spending some more time visualizing the situation before deciding you don't understand it. Clearly the glove didn't move 11cm after it was at rest. Melchoir 23:07, 26 April 2006 (UTC)

Although, actually, there's a second problem with the question. To determine the time-averaged force, you'd have to know the time it took to stop the ball, which you're not given. So you can really only determine the space-averaged force. One way is to assume a constant force, as 12.183.203.184 suggests. Melchoir 23:23, 26 April 2006 (UTC)

For the heck of it I did v2^2 = v1^2 + 2ad with V1 being 30m/s and V2 0 and I get twice the correct answer.

v2^2 = v1^2 + 2ad
(v2^2-v1^2)/(d) = a
(0 - 30^2)/(0.11) = a

a = -8181.81m/s^2
F = ma
F = 0.145(-8181.81)
F = -1186.36

The answer I was given was 588.6. Anyone know why this happens? Thanks. --- C-c-c-c 01:46, 27 April 2006 (UTC)

When you know you're off by a factor of 2, that's a good time to step back through your work and determine where you dropped it. Melchoir 01:52, 27 April 2006 (UTC)

I think your equation is off by two. VT +1/2 AT^2 = D

How much does a flea weigh?

What is a ballpark figure for the weight (or mass) of a typical flea, say for concreteness a hungry adult Pulex irritans? The relevance of this itching question is that the article Planck mass states (without source) that "the Planck mass is on a scale more or less conceivable to humans, as it is roughly the mass of some fleas." The article Flea sheds no light on the issue. I put this question on the talk page of Flea, but in more than a month there has been no reaction – no-one wants to talk about fleas. Lambiam^Talk 22:40, 26 April 2006 (UTC)

(Heh, after reading just your first sentence, I was about to answer "oh, about a Planck mass". Guess that doesn't cut it?) Melchoir 23:34, 26 April 2006 (UTC)

This page indicates that females can consume up to 14 μL of blood per day, amounting to about 150 times their body mass. Assuming a density of blood of a bit more than 1 g/cm³ (close enough for our purposes) 14 μL of blood would weigh about 15 mg. Divided by 150, that's a weight per flea of about 100 μg—I don't know if that would be the dry or full weight, however. Given a Planck mass of about 21 μg, I'd say we're getting well into the realm of 'close enough'. TenOfAllTrades(talk) 00:32, 27 April 2006 (UTC)

Rail gun

Is it possible with todays technology that a actual mass driver such as a railgun could be built? If it was then what would it be made out of and how could the required amount of energy be produced to send a vehicle speeding out of our atmosphere at escape velocity? —The preceding unsigned comment was added by 68.120.231.85 (talk • contribs) 23:25, 26 April 2006.

No, it's not currently possible. One problem is that a projectile (like a rocket) needs to move slower in the thick lower atmosphere to avoid burning up. However, I can imagine a setup where you give a conventional rocket a bit of a push-start with such a device. Some other technology, like compressed air, would also allow you to give a rocket a head start and thus save on fuel it needs to keep onboard. This would allow for much lighter, smaller rockets. It's also far easier to store large quantities of energy as compressed air than as electricity, and electromagnetic interference isn't an issue. StuRat 02:10, 27 April 2006 (UTC)

Also see mass driver, rail gun, and coil gun. StuRat 02:26, 27 April 2006 (UTC)

Thank you that actually was the answer I was looking for. Patrick Kreidt

April 27

Hydrogen as energy source/fuel

Hydrogen is praised as the fuel of the future for it's non-polluting properties, but nowhere have I found how much energy is required in producing a given quantity of energy in hydrogen. The process of hydrogen production can't be better than 100% efficient, and if it uses oil or coal we are just transferring the problem from the end-consumer to the producer. I would like to know something about the efficiency of hydrogen production, and the method(s) used. Researching this subject and publishing the results may clarify the situation, and your efforts would be sincerely appreciated. Henry Boessl —The preceding unsigned comment was added by 63.22.138.50 (talk • contribs) 01:02, 27 April 2006.

You're correct that it takes a considerable amount of energy to produce hydrogen gas. And, of course, there aren't vast quantities of it sitting around like petroleum and coal (although not as huge quantities as there once were). However, hydrogen is a reasonably good way to store and distribute energy. Compared with coal, for example, it can be shipped through pipes and used in cars, while coal isn't suitable for either purpose. So, burning coal and using the energy to produce hydrogen, say by the electrolysis of water, allows you to distribute hydrogen for fuel cells or direct combustion in cars and eventually for other purposes, like home heating. Another advantage is that the pollution created by the coal is at the power plant, and very little pollution is released from the car. By placing the power plants away from dense population centers you can thus reduce pollution in populated areas. Another competing temporary way to store energy is as electricity stored in batteries in the car. At present, however, batteries don't carry much energy relative to their weight, so this may give hydrogen gas the advantage. Energy produced by other non-portable sources, like nuclear, hydro, geothermal, etc., may also be converted into hydrogen gas. I don't see it being worthwhile to convert other portable energy sources, such as petroleum, to hydrogen gas, however. The advantage of moving the pollution away from cities doesn't seem to be worth the energy loss incurred in such a conversion. StuRat 01:32, 27 April 2006 (UTC)

Hydrogen can be produced by reducing steam with coke (the latter being produced from coal). That does make CO2, but possibly less than you'd produce by burning gasoline to power a car to go the same distance. (I say "possibly" because I don't really know; anyone who does know should feel invited to jump in here.) If that's true then total greenhouse emissions could be reduced; even if it isn't, it's still a way to use coal, which the US has a lot of, to power cars. It's surely better than burning it for electricity and then hydrolyzing water.

The only solution I can think of, though, that uses hydrogen to let us keep driving while eliminating greenhouse emissions is to make it using nuclear power. (Yes, the full cycle of nuclear power production does currently produce some greenhouse gases, but that's because mining, construction, etc use fossil fuels; they could be switched over to nuclear-generated hydrogen as well.)

But there is an issue that hasn't yet drawn a lot of attention, but will have to be dealt with if the hydrogen thing really gets going: Hydrogen could cause ozone depletion (hope I don't have to explain why :-). Just how serious the problem is, or how hard it would be to keep the hydrogen from leaking, I don't know if anyone really knows. --Trovatore 02:15, 27 April 2006 (UTC)

Electroysis to breath underwater?

Please help

I am still in grade school and very interested in electricity, and i've read a few books on electricity and i cant seem to really understand if anything answers my question; Is it possible to make an underwater breathing apparatus using materials such as an electrolysis device with like a mouth piece or something that 1 person could use and operate, like a scuba tank, so they could breath underwater? And would it be safe?

Thank-you in advance for you help. --216.197.232.142 03:43, 27 April 2006 (UTC)Gus

I imagine it is technically feasible with an adequate power source, but you would need to think through a few more points, like where is the hydrogen going to go, and how do you safely handle pure oxygen. I think a more interesting question is the that 1 person could use part, whether or not it would be less massive/bulky/dangerous than a simple tank of compressed oxygen. Peter Grey 05:21, 27 April 2006 (UTC)

The power source is probably the biggest problem. If you were going to carry a lead battery to power your electrolysis, it would probably outweigh an equivalent air tank by a large factor (but how large, I don't know). -lethe ^{talk +} 05:24, 27 April 2006 (UTC)

You're right. Basically, the energy density of a lead battery is not very good; the energy you got out of 1 kg of battery is enough to electrolyse only a small fraction of 1kg of water. To do the calculation yourself, you need to know the energy density of a lead-acid battery and how much energy it takes to electrolyse water; both statistics shouldn't be too hard to find. It's unlikely that any conventional power source is likely to be dense enough to pull this off; the latest and most efficient thing in "conventional" submarines is powering them with fuel cells, which is essentially electrolysis in reverse! Nuclear-powered submarines have fuel with enormous energy density, so they indeed use the scheme you describe (as well as devices to remove carbon dioxide, carbon monoxide, and other contaminants from the atmosphere) to provide breathable air on their very long voyages.

--Robert Merkel 06:28, 27 April 2006 (UTC)

Maybe I can make a rough stab at the math. From [21] I get that, say, 1 kg of water would require $1.59\times 10^{7}{\mbox{ J}}$ to dissociate into an atmosphere (in other words, into your helmet or so). From this, you'd get 889 grams of oxygen. That much energy at, say, the 1.6 eV per electron in a silver-oxide battery, is $6.19\times 10^{25}$ electrons. You get two per reaction, and each reaction involves 297 amu of reacting material (not counting catalysts, but in theory they can be amortized over many reactions). So that's 15.3 kg of reactant to "power" 889 grams of oxygen (factor of 17.2). You're probably better off just carrying the oxygen; while the oxygen tank adds some weight, the battery structure and electronics and electrolysis equipment would add a good bit too. --Tardis 07:12, 27 April 2006 (UTC)

Followup: As Peter Grey touched on, can you, in fact, create a breathable mixture solely from hydrogen and oxygen (and compounds of the two)? If not, this device would presumably have to process and recycle the diver's exhaled air just as the submarines. ×Meegs 08:02, 27 April 2006 (UTC)

Dimensionally prove the simple pendulum equation!

Sir, there is the prove of simple pendulum equation or formula but there is no dimensional analysis of this formula to check weather it is correct dimensionally or not, For just studing for college--80.231.14.119 06:58, 27 April 2006 (UTC)

What? Melchoir 07:02, 27 April 2006 (UTC)

Er, if it's been proven, you don't need to do dimensional analysis. Dimensional analysis finds bugs, but proof precludes them (notwithstanding any bugs in the proof!), so the analysis would be redundant. Why would you want it specifically? --Tardis 07:14, 27 April 2006 (UTC)

Sir i want for studing for college.i know its all right proof but for my personal studies i want proof of Dimensional analysis. If u write for me i am very thank ful to you--80.231.14.119 07:31, 27 April 2006 (UTC)

Since it's so insanely easy we may as well do it for you. You haven't specified which formula you want, so I'm going to do the period for the small angle approximation, $T_{0}=2\pi {\sqrt {l \over g}}$.

$T_{0}$ is a time, so it has dimensions of T. $2\pi$ is a dimensionless constant. $l$ is a length, dimensions of L. $g$ is an acceleration, dimensions of LT^-2. So, $l \over g$ has dimensions of L/(LT^-2) = T², and its square root therefore has dimensions of T, as required.

If it's some other formula you wanted have a go at it yourself. --Bth 07:37, 27 April 2006 (UTC)

Thanks sir i am very very thankful ,remmember that this is the only site which help me in studies! whole google search not give me such type of intresting site Sir--80.231.14.119 07:46, 27 April 2006 (UTC) Give the drawbacks to use the time period of pendulum as a time standard--80.231.14.119 07:54, 27 April 2006 (UTC)

OK, see, if you're going to get us to do your homework, you have to work hard at pretending that it's not. Quoting the next question in such obvious "this is a question" form is a dead giveaway. I'm sorry I helped you now. --Bth 08:15, 27 April 2006 (UTC)

"Give the drawbacks to use the time period of pendulum as a time standard"if any--80.231.14.119 08:23, 27 April 2006 (UTC)

Erm, you seem to have misunderstood - please read the rules at the top of the page, we are here to help with concepts and try and answer general questions, but we strongly object to doing your homework for you. Your question "Give the drawbacks to use the time period of pendulum as a time standard, if any" smells very strongly of homework, so we won't help you, as it won't do you any good to have others do your work for you. Please come back when you have finished your homework. — QuantumEleven 08:32, 27 April 2006 (UTC)

photons

Anything that moves at light speed has infinite mass.The photon has no mass.How does this explain RADIATION PRESSURE?

Anything with a rest mass cannot reach light speed in the first place, because to do so would require infinite energy. Anything with a zero rest mass can only travel at light speed. Photons still have energy (equal to Planck's constant times their frequency), and it's the transfer of that energy that ultimately accounts for radiation pressure. --Bth 08:24, 27 April 2006 (UTC)

Hepatits School Project

I need to find out specific numbers of the incidents and deaths for most of the countries of the world. If anyone can help please I really need it. Thanks

For every single country in the world there are some incidents and deaths from the disease Hepatitis. I require the specific number for each country. Anything Helps!! --204.218.240.30 08:20, 27 April 2006 (UTC)