Wikipedia:Reference desk/Science

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October 28

Lipofuscin,dementia and age spots

What is the chemical formula of lipofuscin and is it the same chemical involved in dementia and age spots.

If known what causes its production?

Richard

The article on lipofuscin has some of the answers that you seek. Dismas|^(talk) 00:47, 28 October 2005 (UTC)

Lipofuscin can accumulate in many cell types but I do not think it is specifically associated with age spots; they seem to be due to uneven distribution of melanin. Some neurodegenerative disorders have been associated with lipofuscin accumulation. Lipofuscin is not a single chemical; here is a more detailed article about a major retinal lipofuscin associated with macular degeneration: Biosynthesis of a major lipofuscin fluorophore in mice and humans with ABCR-mediated retinal and macular degeneration. There have been attempts to find associations between Alzheimer's disease and lipofuscin, but I don't think links have been demonstrated. --JWSchmidt 04:53, 28 October 2005 (UTC)

white blood cells

Has there been any scientific studies that prove a positive reaction to building white blood cells in an aging male? For example: taking a certain vitamin?

Thank you,

Sandra Crosson

— Preceding unsigned comment added by 71.244.229.60 (talk • contribs)

Can you rephrase more clearly?

I don't understand what you mean by building: increasing the number of white cells or making them different in some way?

I don't understand what you mean by positive reaction: a detectable effect of building white blood cells or a detectable beneficial effect of building white blood cells?

Are you asking if taking a certain vitamin increases WBC count?

Are you asking if it is beneficial to increase the number of WBCs?

You are aware that too few WBCs are bad and too many WBCs are bad? That making more if you have too many is not necessarily beneficial? That there is no demonstrable advantage to having a WBC count of 9,000 per mm3 instead of 8,000 in a healthy person? alteripse 03:20, 28 October 2005 (UTC)

Restorative Dentistry

What does "recement" mean? It is in benefits lists for dental insurance, and used in the context of "recement crown", "recement inlay" or "recement cast".

--64.174.7.191 03:16, 28 October 2005 (UTC)

At a wild guess, try reading as "re-cement", or "apply cement to [a crown, inlay or cast] a second time". Notinasnaid 07:18, 28 October 2005 (UTC)

The word "recement" means exactly what it literally says. Dental restorations--that is to say, devices used to re-construct the shape and form of a damaged tooth (i.e., fillings, inlays, crowns, or veneers) often (but not always) need to be cemented to a tooth in order for them to be reliably retained in place. However, they don't always stay in place forever. The combined action of salivary dissolution and repetitive chewing force can cause disintegration of the luting cement over time, leading to loosening and displacement of the restoration. If there is no significant damage to the tooth by decay and the restoration still fits, it can be recemented in its proper position.

Whether a dental insurance policy pays a benefit for a recementation procedure depends on the provisions of the policy. However, most dental insurance carriers would much rather pay for a low-cost procedure such as a recementation than pay for an expensive replacement of an otherwise serviceable dental restoration. In the U.S., the insurance industry and the American Dental Association have collaborated on a set of procedure codes, and there are codes for recementation, giving the technique official recognition. --
Mark Bornfeld DDS
dentaltwins.com
Brooklyn, NY 18:49, 28 October 2005 (UTC)

GPS Protocols

No-where on the internet can I find any reference of an NMEA protocol to Garmin protocol converter. Does such a thing exist ? What I am actually seeking to do is to use my GPS receiver (NMEA protocol) to find my location on Google Earth (which only uses Garmin / Magellan inputs). Any joy anyone please ? Thanks so much--jrleighton 03:42, 28 October 2005 (UTC)

(moved from Wikipedia Talk:Reference desk by Garrett Albright 04:09, 28 October 2005 (UTC)

Interesting question. This document about the NMEA standard describes the NMEA protocol (for the benefit of the nautically challenged, NMEA is a standard interface for transferring navigational information between electronic devices on boats). It looks like it's implemented on stop of some very standard serial communications protocols, so it should be very straightforward to build a gadget that speaks and understands NMEA. As to speaking the Garmin/Magellan protocol, I don't know if the protocol is public. It probably wouldn't be difficult to reverse engineer, however. However, given that GPS units are incredibly cheap these days, by the time you've purchased all the components to build a converter it may have been cheaper just to buy an appropriate GPS; which is probably why you can't buy a Magellan protocol to NMEA protocol converter!--Robert Merkel 06:18, 28 October 2005 (UTC)

science / history

Why do different science disciplines not cross reference each other? Hence we seem to end up with only 20,000 years of human history but the globe being populated by man crossing land bridges that existed millions of years ago and no-one in the science community questions this.

• I'm not sure what the problem is with that. It is frequently accepted that man has been around a lot longer than modern history has records (which means history goes back around 5200 years), and that none of the early histories came down to us. What was happening before that is interesting, and studied as prehistory. What should the science community be questioning? Notinasnaid 08:02, 28 October 2005 (UTC)

Landbridges did not only exist "millions of years ago." The Bering land bridge, which connected Siberia and Alaska, was in existence 22,000 - 7,000 years ago, well within the "20,000 years of human history" that you have cited. I agree with Nitinasnaid: I don't think I understand your point. If it is that different scientific disciplines don't overlap and cross-reference one another, I think you are mistaken. Neuroscience and biochemistry are two good examples. So is geology, which borrows from physics, biology, and chemistry, among other disciplines. If your point is that the wisdom found in history and science are mutually exclusive, I have to disagree. -Parallel or Together? 08:12, 28 October 2005 (UTC)

I accept weather changes geography in much shorter time scales than geology, but everything I have read indicates Africa is the cradle of humanity but Australia has the oldest tracable records of mankind and links to Australia severed through continental drift, not climate change.

Modern Homo sapiens came to Australia between 40,000 and 60,000 years ago by land bridges and perhaps small-distance sea crossing (see Prehistory of Australia). On the other hand, Homo sapiens appeared in Africa around 200,000 years ago (see Human evolution). Humans may have migrated from Africa to Australia in that span of 140,000 years (this is the single-origin hypothesis). Or Homo sapiens may have independently evolved in different areas of the world from the local Homo erectus populations, who themselves had migrated out of Africa many thousands of years before (this is the multiregional hypothesis). Does this help or did I misunderstand you again? (if so, I apologize). -Parallel or Together? 09:13, 28 October 2005 (UTC)

Helpfull - Thank you.

You left out the alien contact hypothesis made famous by von Däniken. Aliens carried man all over the globe! If it wasn't for those meddling aliens, we would have gotten away with it too... Dominick ^(ŤαĿĶ)

Haha, you are right. This was a significant oversight on my part. Please forgive me. -Parallel or Together? 14:10, 28 October 2005 (UTC)

One thing that should be clarified is that the sub-species homo sapiens sapiens refers to modern humans, while the species homo sapiens also includes ancient humans, such as Homo sapiens idaltu. StuRat 17:01, 28 October 2005 (UTC)

White blood cell

How does the body get rid of WBC??? What i mean is that RBC are destroyed in the spleen and liver, so where are the WBC destroyed??? And also why do RBC do not have nucleus, by having one it can increase its lifespan, why not???

Thank you for you time...:)

The average life-span of neutrophils is about 11-16 days, most of which is spent maturing in the bone marrow. About 24 hours after they are released into the circulatory system, they undergo apoptosis and are phagocytized by other cells. As for RBCs, you probably know that some animals normally have circulating nucleated RBCS, but that most mammals, including humans, don't. Mammals have smaller end-vessels in their circulatory systems: small enough that RBCs must be able to be deformed (squeezed) to pass through them - easier if they are smaller and enucleate. In addition, an RBC with no nucleus can contain a higher hemoglobin concentration and therefore carry more oxygen. - Nunh-huh 16:53, 28 October 2005 (UTC)

Factorial

Could someone please explain how to calculate decimal factorials (ex. 7.35! or 3.9!)? I found the explanation at Factorial a bit confusing. Don Diego^(Talk) 16:16, 28 October 2005 (UTC)

• In general, you have to calculate the Gamma function for the argument plus one. This isn't particularly easy, so you're better off looking up the result in a table. --Bob Mellish 16:31, 28 October 2005 (UTC)

• Basically, to get n! you have to evaluate $\int _{0}^{\infty }x^{n}e^{-x}dx$. I doubt there's an easier way, except for certain specific values. —Keenan Pepper 17:11, 28 October 2005 (UTC)
  • Note that that's actually how you calculate (n-1)!. Incidently, Window's Calc.exe will cheerfully handle non-integer factorials. --Bob Mellish 19:03, 28 October 2005 (UTC)

No, that's n!. The gamma function is shifted by one, but the integral I gave is not.

—Keenan Pepper 19:29, 28 October 2005 (UTC)

• Ah yes, I see now. Sorry. --Bob Mellish 23:21, 28 October 2005 (UTC)

• • There are easier ways than evaluating the the integral directly. I have written a 15-line implementation of Lanczos approximation for the Gamma function in Python which is currently available at the Swedish Wikipedia. The Gamma function is implemented by pretty much any decent mathematics software, and there is also an online arbitrary-precision calculator at http://oldmill.uchicago.edu/~wilder/Code/hpgamma/. Not much hope calculating it by hand, though. Fredrik | talk 19:28, 28 October 2005 (UTC)

Ooooh - this caught my attention. I didn't know that there was such a thing as a "Lanczos approximation" outside of quantum mechanics! Another score +1 for the RD :-) --HappyCamper 03:54, 29 October 2005 (UTC)

Direction of data on CDs

Does the data on a CD start at the outside and go inward, like a vinyl record, or vice versa? Clockwise or counter-clockwise? What about DVDs? Are there any media that go the "wrong" way? —Keenan Pepper 17:15, 28 October 2005 (UTC)

It goes inside and out, as you can verify by looking at a blank CD-R and one that's partially full. As for the direction, that would be clockwise (assuming you're looking at the data side of the disc), as that's the direction a CD spins in a CD player. --Pidgeot (t) (c) (e) 18:40, 28 October 2005 (UTC)

There is also plenty more information on compact disc that's worth looking at :) ☢ Ҡieff⌇↯ 20:00, 28 October 2005 (UTC)

I've heard that Gamecube discs have the data track spiraling the opposite direction; I'm not sure if they record it from the outside in, or if the disc actually rotates in the opposite direction. --David Wahler (talk) 20:01, 28 October 2005 (UTC)

You wouldn't have to spin it backwards to record, you could just reverse the order of the bits when recording it. It would be interesting to find out if they do this though, it would certainly make piracy harder. --Quasipalm 21:20, 28 October 2005 (UTC)

A GameCube disc isn't all that different from a regular disc, they just use a proprietary filesystem and disc structure that a regular DVD drive can't read. It doesn't spin "the wrong way" around. (If it did, I'd imagine it would have been a nightmare to make the Panasonic Q work.) --Pidgeot (t) (c) (e) 21:48, 28 October 2005 (UTC)

You may be thinking of the X box, which by default reads data from the outside, inward. Nothing stops it from being compatible with standard CDs and DVDs, but the native Xbox read mode is backward from normal media.

birds

how many species of birds are there? - anon

Second paragraph of Bird. ;) —Keenan Pepper 19:32, 28 October 2005 (UTC)

Lymph Nodes

can someone please tell me how many Lymph Nodes are under you left arm.

Thanks Sue M.

Sue, there is no specific number of lymph nodes in the left armpit (these would be called left axillary nodes, by the way). The number differs from person to person, from very few (less than five) to more than thirty. One study (in women with breast cancer) showed an average of about 10 lymph nodes per axilla. - Nunh-huh 21:36, 28 October 2005 (UTC)

Potential Energy/ Kinetic Energy/ Conservation of Energy / Linear Momentum

What is the exact mathamatical relationship between momentum, initial momentum, final and change in energy? conservation of energy? thank you--152.163.101.12 21:08, 28 October 2005 (UTC)

• $p=mv$ (momentum is mass times velocity)
  
• $I=mv-mu$ (Impulse is change in momentum)
  
• $I=Ft$ (Impulse is force times time)
  
• $E=0.5mv^{2}$ (Energe is half mass times velocity squared)
  

• Conservation of energy is just "Energy cannot be created or destroyed", it can only be converted into other forms of energy. For example, an object falling loses gravitational potential energy and gains kinetic energy. Heat, sound, gravitational potential, elastic potential... the list goes on. But it's all conserved. Deskana 22:09, 28 October 2005 (UTC)

However, note that Einstein taught that energy alone is not always conserved, nor mass alone, but both are conserved in accordance with $E=mc^{2}$. Mass is regularly changed to energy, in the Sun, in nuclear reactors, in nuclear weapons, and in radioactive minerals. Energy can also theoretically be changed into mass, although we haven't found a way to do so yet. Of course, in normal (non-nuclear) reactions, the conservation of energy is perfectly valid. StuRat 00:54, 29 October 2005 (UTC)

Actually, energy gets converted to mass all the time—for instance, a pair of photons producing a particle-antiparticle pair. And if I recall correctly, even in ordinary energy transfers, a tiny amount of the energy causes the mass to increase by a tiny amount (even in heat transfers or chemical recations)...but I could be wrong about that. In any case, I think that for the purposes of the principle at least, mass can be regarded as a special form of energy, and conservation of energy still holds. Note that it may not hold on short time scales in quantum mechanics. — Knowledge Seeker দ 04:30, 29 October 2005 (UTC)

It actually does hold, always, provided you define "energy" in the right way. ;) More specifically, even on short time scales in quantum mechanics, physicists assume conservation of energy and allow virtual particles to have the "wrong" mass; this is often explained instead as an energy-time uncertainty principle, but that's probably less accurate. -- SCZenz 22:10, 29 October 2005 (UTC)

October 29

Porous Steel?

When Steel is boiled in water does it have pores which open up to absorb? Such as when traps are boiled in Walnut hulls or logwood dye and they take on a darker color. The question is does steel have pores?

The only increase in "pore" size you wuold have would be the expansion of the steel and thus the increase of intermolecular distances. So no, steel doesn't have pores. --Borbrav 00:30, 29 October 2005 (UTC)

Darkening of steel after boiling with plant extract would be a result of either staining or oxidation. alteripse 00:42, 29 October 2005 (UTC)

Always something new: Porous Steel. --JWSchmidt 23:20, 29 October 2005 (UTC)

Silverwing

If you've ever read the Silverwing series of books you know that there are two species referenced called the Silverwing and Brightwing bats. A lot of the other species seem to be based on real ones, so does anyone know what Silverwings and Brightwings could possibly be in real life? Thanks for the help! ♥♥purplefeltangel♥♥ 00:48, 29 October 2005 (UTC)

By the way, Silverwings are said to have short, broad silver wings and short tails, while Brightwings have long, narrow wings, bright fur, and "elegant" ears. ♥♥purplefeltangel♥♥ 06:53, 29 October 2005 (UTC)

It sounds like it could be a species of moth, perhaps even tropical moths. Does this help? --HappyCamper 11:52, 29 October 2005 (UTC)

Uh, they're bats. :D I'm asking what bat species they are. ♥♥purplefeltangel♥♥ 21:34, 29 October 2005 (UTC)

Quote from author here [www.kennethoppel.ca]:

"All my characters are based on real species of bats -- even Goth and Throbb! Shade's a silver-haired bat; Marina's a red bat, Goth is something called a spear-nosed bat, also known as the Vampyrum Spectrum. Cama Zotz is based on a real Mayan bat deity of the same name. I also wanted to pick names that seemed appropriate for flying creatures. So I used the names of some angels (Cassiel, Ariel), the names of special winds (Zephyr, Chinook, Scirocco -- you can look them up!) and mythic heroes (Icarus). As for Shade, his name just reminded me of shadows and twilight. Marina means "of the sea" -- she lives on an island as the story begins. And Goth is kind of shorthand for the word "gothic" -- which conjured up all sorts of images of vampires and dungeons"

There you go. Prodego ^talk 21:52, 29 October 2005 (UTC)

Do rats really eat feces?

More specifically, is dog poop really a significant food source for rats? Even more specifically, if I keep my collected dog poop (individually wrapped in do-do-bags) in an open container in my bushes in Florida and then I see a rat, is the poop likely to be a significant cause of the presence of the rat? Note that some city governments list dog feces cleanup as a critical rat-prevention tactic. They also indicate that rats "spread disease" but I think this fact is also disputed.

Rats are suspected of aiding in the spread of the bubonic plague during the Black Death pandemic... although this fact is indeed somewhat disputed. However, rats are technically cabaple of spreading disease, it is just not proven beyond a shadow of a doubt that they did so in this particular instance. And yes, rats eat their own feces[1] so they might also eat dog feces. -Parallel or Together? 12:35, 29 October 2005 (UTC)

I would say that if you find the bags have been chewed up with the feces strewn about the container, suspect the rats. If the bags remain undisturbed, I would probably not worry about it attracting the rats. Dismas|^(talk) 04:41, 30 October 2005 (UTC)

Actually, as I understand it, what is not certain is that the black death was bubonic plague, but the plague is spread by rats. Or, rather, strictly speaking, it's the fleas that live on the rats that infect humans (which is why it's a bad idea to kill rats when there's an outbreak - the fleas will switch to humans). But, more on the subject, coprophagy is a way for rodents to get all the nutritional value out of their food. In the case of rabbits, they have two different kinds of droppings; the ones you get to see are the second kind because the first is eaten. Apparently, dogs also do this, but not (necessarily) for the same reason. So I wonder if dog poo has the qualities (nutritional value) that a rat would be looking for. Then again, the rats might just be plain stupid and not realise that they're doing something useless. Shit happens, so to say. DirkvdM 06:36, 30 October 2005 (UTC)

What is the most intelligent insect?

Or has nobody really bothered to find out? Kid Apathy 13:20, 29 October 2005 (UTC)

While nobody knows for sure (as they keep dropping their number 2 pencils when taking standard IQ tests), I would hazard a guess and say bees. Social animals have an inherent need for greater intelligence to communicate with others in their group. In the case of bees, they are known to communicate the location of food via a "dance" performed in the hive. However, insect intelligence is thought to be almost entirely instinct, with very little capacity for true learning. This explains how such apparent intelligence can be packed into such a small brain. Instinctive behaviours require far less brain mass than learning. StuRat 13:26, 29 October 2005 (UTC)

Take a look at Mushroom bodies. If you want more, try this: Evolution, Discovery, and Interpretations of Arthropod Mushroom Bodies --JWSchmidt 23:11, 29 October 2005 (UTC)

Depends on how you define intelligence, of course, and that's a tricky one. Any definition will be anthropomorphic. By such a definition you'd be hard put to find any intelligence in insects at all. As StuRat says, insect 'intelligence' is basically instinct. Human intelligence is an ability to adapt to changing circumstances (learning). But this sort of intelligence is not what makes insects tick (no pun intended). There are different ways to be successful as a species. Intelligence is one of them, and it happens to be the one that homo sapiens has specialised in. Other methods are evolution and numbers. Insects as they are may produce so much offspring that some of them will find the right habitat to survive. On top of that, variation will lead to evolution. But humans don't have quite as much offspring and live much longer (making evolution work slower). So they use intelligence (which can be seen as a form of evolution in one individual).

Sturat also mentions bees, but my bet is on ants. Here, however, the intelligence is not in the individuals, but in the 'hive' (what's that called with ants?). Individually, ants are pretty stupid (even working against each other), but as a group they can move mountains (well, create mounds, anyway). DirkvdM 07:05, 30 October 2005 (UTC)

Bees, ants, yes, but Jiminy Cricket is no fool either. David Sneek 09:19, 30 October 2005 (UTC)

• I think we'd have to define intelligence first, and whether or not we recognize collective or emergent intelligence (which is how the social insects would win) or whether or not we are considering individual intelligence. Ants and bees on the individual level are doing nothing more than following a fairly preset series of commands — it's just that those commands, spread among a few thousand individuals, can create some pretty neat results. I'm not sure how you'd measure individual intelligence in insects (problem solving?) and I'm not sure anyone has tried to. --Fastfission 15:26, 30 October 2005 (UTC)

One could say that humans are also a collection of (by themselves) stupid cells that only display intelligence when they cooperate. Our cells are just stuck together, whereas ants have the freedom to move around by themselves. But they also have to stick to the collective to survive. Which is sort of a communist (or fascist) society. Which is why communism and fascism will never work; the constituent parts are just too individualistic. Fyi :) . DirkvdM 08:08, 31 October 2005 (UTC)

I would say ants are likely to be the most 'intelligent', though that is fairly broad as there are hundreds of species. As some species have developed agriculture (of fungi & captured aphids), slavery & warfare. These are pretty strong indicators of intelligence in humans, though not - for the last 2 - of social conscience or morality.AllanHainey 15:25, 31 October 2005 (UTC)

Related question: Has an insect exhibited tool use? --Fangz 20:57, 31 October 2005 (UTC)

The Portia spider appears to be quite cunning. Some of its behavious are practically mamalian. It's quite creepy if you've ever seen them in action. Vonspringer 04:26, 1 November 2005 (UTC)

A division question

I'm having trouble dividing $3x^{4}+5x^{3}-2x^{2}+6x+3$ by $x+2$. Could someone please show me how so that I can solve the problem and then apply the method I've learned to other, similar problems? Thanks, anon.

That's called synthetic division. See that article for details. StuRat 17:18, 29 October 2005 (UTC)

On second thought, a better introduction to the material is located at Polynomial long division. StuRat 17:23, 29 October 2005 (UTC)

The 'do your own homework' thing has made students smarter, I see. :) DirkvdM 07:08, 30 October 2005 (UTC)

Telnet option 200?

Half curiosity, half pragma (implementing my own telnet option parser for a new MUD codebase), but what does telnet option 200 (C8 in hex) signify for MUDs and MUD clients? Google draws a blank, and it's an 'unofficial' option as far as RFCs and their ilk are concerned. So does anyone know what this does, or shall it be consigned to the pit of obscurity?

The only reference I could find to it is [2], where you can also see another mysterious telnet option: 170. I also found about options 85 (Mud Compression Protocol, v1), 86 (Mud Compression Protocol, v2), 90 (Mud Sound Protocol), and 91 (Mud Extension Protocol). Which client or server is sending you option 200? --cesarb 00:12, 30 October 2005 (UTC)

I'm seeing it come up on IRE muds, when Rapture is sending the initial option communication, along with 86 (COMPRESS2) and asking if EOR is OK (can't recall the number off hand. Probably nothing, because MUSHclient just says no to number 200, but it's a curiosity. --Sam Pointon 10:53, 30 October 2005 (UTC)

WWII German Enigma Machine

The WWII German Enigma machine is based on what mathematical models? In other words, what is the primary mathematical basis of the Enigma? Do you know of any websites that provide a discussion of its mathematical basis?--158.80.0.2 19:12, 29 October 2005 (UTC)

• How's about The Cryptographic Mathematics of Enigma from the NSA? --jpgordon∇∆∇∆ 20:09, 29 October 2005 (UTC)

biology

why are plants green?

1. Chlorophyll, the chemical they use to absorb energy from sunlight, is green. -- SCZenz 22:07, 29 October 2005 (UTC)

Another way to explain that is that chlorophyll absorbs and transduces light of the reddish wavelengths most efficiently, and it reflects most light of green wavelengths. alteripse 22:17, 29 October 2005 (UTC)

Plants are all "green with envy" that animals get to move around and they don't. StuRat 16:47, 30 October 2005 (UTC)

Transverse meridional/"great-ellipse" arcradius?

Consider the loxodromic equations:

   $VLeg$ = The "vertical" (Δlatitude) "leg";
   $HLeg$ = The "horizontal" (adjusted Δlongitude) "leg";

    $Azg$ = Graticular (spherical) azimuth;

   $HyP_{g}$ = Loxodromic hypotenuse;

$VLeg=\cos \!\left\{Azg\right\}\times HyP_{g}=|\Delta Latitude|;$

$HLeg=\sin \!\left\{Azg\right\}\times HyP_{g}={\frac {VLeg\times |\Delta Longitude|}{\operatorname {arccosh} \!\left\{\sec \left\{Lat_{2}\right\}\right\}-\operatorname {arccosh} \!\left\{\sec \left\{Lat_{1}\right\}\right\}}};$

For the spherical loxodrome:

$Azg=\arctan \!\left\{{\frac {HLeg}{VLeg}}\right\};$

$HyP_{g}={\sqrt {VLeg^{2}+HLeg^{2}}};$

For the ellipsoidal loxodrome (referring here to an oblate ellipsoid [$a>b$]):

    $a,b$ = equatorial, polar radii;

$\operatorname {M} \!\left\{Lat\right\}=\!\left\lbrack {\frac {a}{b^{2}}}\right\rbrack ^{2}\operatorname {N} \!\left\{Lat\right\}^{3}\quad {\mbox{(Meridional arcradius/radius of curvature)}};$

$=k_{1}\,\!$?

$\operatorname {N} \!\left\{Lat\right\}=\!{\frac {a^{2}}{\sqrt {(a\times \cos \!\left\{Lat\right\})^{2}+(b\times \sin \!\left\{Lat\right\})^{2}}}}\quad {\mbox{(Normal/transverse equatorial arcradius)}};$

$=k_{2}\,\!$?

$a\times \operatorname {HyP} _{e}\!\left\{Lat\right\}$	$={\sqrt {(VLeg\times \operatorname {M} \!\left\{Lat\right\})^{2}+(HLeg\times \operatorname {N} \!\left\{Lat\right\})^{2}}},$
	$={\sqrt {(\cos \!\left\{Azg\right\}\times HyP_{g}\times \operatorname {M} \!\left\{Lat\right\})^{2}+(\sin \!\left\{Azg\right\}\times HyP_{g}\times \operatorname {N} \!\left\{Lat\right\})^{2}}},$
	$={\sqrt {(\cos \!\left\{Azg\right\}\times \operatorname {M} \!\left\{Lat\right\})^{2}+(\sin \!\left\{Azg\right\}\times \operatorname {N} \!\left\{Lat\right\})^{2}}}\times HyP_{g},$
	$=\operatorname {O} \!\left\{Azg:Lat\right\}\times HyP_{g};$

The ellipsoidal loxodromic azimuth has its own relationship set:

$\sin \!\left\{Azg\right\}\times \operatorname {N} \!\left\{Lat\right\}$	$={\sqrt {\operatorname {O} \!\left\{Azg:Lat\right\}^{2}-(\cos \!\left\{Azg\right\}\times \operatorname {M} \!\left\{Lat\right\})^{2}}},$
	$=\operatorname {O} \!\left\{Azg:Lat\right\}\times {\sqrt {1-(\cos \!\left\{Azg\right\}\times {\frac {\operatorname {M} \!\left\{Lat\right\}}{\operatorname {O} \!\left\{Azg:Lat\right\}}})^{2}}},$
	$=\operatorname {O} \!\left\{Azg:Lat\right\}\times \sin \!\left\{Aze\!\left\{Lat\right\}\right\};$

Likewise,

$\cos \!\left\{Azg\right\}\times \operatorname {M} \!\left\{Lat\right\}=\operatorname {O} \!\left\{Azg:Lat\right\}\times \cos \!\left\{Aze\!\left\{Lat\right\}\right\};$

Hence,

$\sin \!\left\{Aze\!\left\{Lat\right\}\right\}=\sin \!\left\{Azg\right\}\times {\frac {\operatorname {N} \!\left\{Lat\right\}}{\operatorname {O} \!\left\{Azg:Lat\right\}}};$

$\cos \!\left\{Aze\!\left\{Lat\right\}\right\}=\cos \!\left\{Azg\right\}\times {\frac {\operatorname {M} \!\left\{Lat\right\}}{\operatorname {O} \!\left\{Azg:Lat\right\}}};$

$\tan \!\left\{Aze\!\left\{Lat\right\}\right\}=\tan \!\left\{Azg\right\}\times {\frac {\operatorname {N} \!\left\{Lat\right\}}{\operatorname {M} \!\left\{Lat\right\}}}={\frac {HLeg\times \operatorname {N} \!\left\{Lat\right\}}{VLeg\times \operatorname {M} \!\left\{Lat\right\}}};$

The point of all this, is that it calls into question the validity of the classically prescribed arcradius at a given latitude, in a given direction:

$\operatorname {O} \!\left\{Azg:Lat\right\}$	$={\sqrt {(\cos \!\left\{Azg\right\}\times \operatorname {M} \!\left\{Lat\right\})^{2}+(\sin \!\left\{Azg\right\}\times \operatorname {N} \!\left\{Lat\right\})^{2}}},$
	$={\frac {\operatorname {O} \!\left\{Azg:Lat\right\}}{\sqrt {\cos \!\left\{Azg\right\}^{2}+\sin \!\left\{Azg\right\}^{2}}}},$
	$={\frac {1}{\sqrt {\left[{\frac {\cos \!\left\{Azg\right\}\times \operatorname {M} \!\left\{Lat\right\}}{\operatorname {M} \!\left\{Lat\right\}\times \operatorname {O} \!\left\{Azg:Lat\right\}}}\right]^{2}+\left[{\frac {\sin \!\left\{Azg\right\}\times \operatorname {N} \!\left\{Lat\right\}}{\operatorname {N} \!\left\{Lat\right\}\times \operatorname {O} \!\left\{Azg:Lat\right\}}}\right]^{2}}}},$
	$={\frac {1}{\sqrt {\left[{\frac {\cos \!\left\{Aze\!\left\{Lat\right\}\right\}}{\operatorname {M} \!\left\{Lat\right\}}}\right]^{2}+\left[{\frac {\sin \!\left\{Aze\!\left\{Lat\right\}\right\}}{\operatorname {N} \!\left\{Lat\right\}}}\right]^{2}}}},$
	$=\operatorname {O_{e}} \!\left\{Aze\!\left\{Lat\right\}:Lat\right\};$

At a given point, an azimuth is an azimuth: Whether it is loxodromic or orthodromic only identifies the "behavior" of the line it represents--an azimuth of 73.263° means, at a given point, a direction of 73.263° from due north, PERIOD (end of discussion). Right?

Now consider the prescribed, accepted equation of the arcradius:

   $Azg$ = Graticular (spherical), orthodromic azimuth at Lat;

   $Aze$ = Elliptical, orthodromic azimuth at Lat;

$\operatorname {P} \!\left\{Aze:Lat\right\}={\frac {1}{{\frac {\cos \!\left\{Aze\right\}^{2}}{\operatorname {M} \!\left\{Lat\right\}}}+{\frac {\sin \!\left\{Aze\right\}^{2}}{\operatorname {N} \!\left\{Lat\right\}}}}};$

If one calculates a minuscule (ellipsoidal geodetic/orthodromic) distance and divides it by the spherical angular distance ("ADg", found via the "spherical cosines for sides" equation), it will nearly equal O_e{$Aze:Lat$}, not P{$Aze:Lat$}!
Consider this example (where $a=6378.136$, $b=6356.75$):

 $Lat_{1}=33.682045083^{\circ };$

 $Lat_{2}=33.682045085^{\circ };$

   $\Delta Long=\ \ 0.000000003^{\circ };$

$ADg=\ \ 0.00000000986412851^{\circ },$

 $=\ \ 0.00000000017216152034{\mbox{ rad}}\,\!;$

 $Azg=78.30189780458^{\circ };$

 $Aze=78.35474883236^{\circ };$

$Distance=\ \ 0.00000109899218359{\mbox{ km}}\,\!;$

${\frac {Distance}{ADg}}=\mathbf {6383.49487983} {\mbox{ km}};$

Now compare:

$\operatorname {O_{e}} \!\left\{Aze:Lat\right\}=\mathbf {6383.49487983} {\mbox{ km}}=\operatorname {O} \!\left\{Azg:Lat\right\};$

 $\operatorname {P} \!\left\{Aze:Lat\right\}=\mathbf {6383.49} {\mathit {759558}}{\mbox{ km}};$

This should demonstrate that O_e{$Aze:Lat$} is the arcradius at ($Aze,Lat$), not P{$Aze:Lat$}, shouldn't it? If O_e{Aze:Lat} is not THE arcradius, then what type of arcradius is it? And if P{$Aze:Lat$} is THE arcradius, then how does it relate to a minuscule distance?

I can't believe this concept is unknown—maybe archaic/obscure and/or just forgotten (or, more likely, known/recognized by another name—?).
Given that "original research" is a Wikipedia no-no, I would like to know if this concept/equation is recogized—or, if indeed this is OR, worthy of a paper at PlanetMath or some such site! P=) ~Kaimbridge~ 23:46, 29 October 2005 (UTC)

Don't take this the wrong way, but: what exactly have you been huffing? Kid Apathy 23:43, 29 October 2005 (UTC)

To put it more politely, the supporting math is fine, but please start with an English description of what you are trying to prove, in layman's terms. StuRat 16:44, 30 October 2005 (UTC)

(comment and reply moved from my talk page—shouldn't the the discussion stay here?) ~Kaimbridge~ 20:36, 30 October 2005 (UTC)

Hmm...very interesting question...What is the context of the original problem? --HappyCamper 01:49, 30 October 2005 (UTC)

Well, the "arcradius" itself is the problem! P=)
I know about geodetic formulation and its "conformal" nature, requiring an "auxiliary sphere" (I have copies of Sodano's and Vincenty's classic papers--as well as others--but I prefer Saito's straight-forward Gaussian Quadrature, all of which are given in Richatd Rapp's Geometric Geodesy, Part II <Ohio State Univ.>). Since great-circle distance equals the (arc)radius times the angular distance, it follows that the (arc)radius equals the distance divided by the angular distance. So, on an ellipsoid, the smallest possible geodetic distance divided by its corresponding graticular/spherical angular distance equals the arcradius at that latitude, in the direction of the geodetic line. Try it on a meridian (which is a "simple" ellipse): Calculate a minuscule distance and divide it by ΔLat (which, in this case, equals the graticular angular distance)—it will nearly equal M{Lat}/O{0:Lat}.
Now, before you get ahead of the discussion and think "hey, wait a minute, I know what he is up to...he thinks he found a geodetic formula using just Lat/Long, not requiring an auxiliary sphere and all its complications...but he doesn't realize...". But, yes, I do realize this wouldn't find the traditionally defined, conformal geodetic distance, but it does find the graticular geodetic distance—what I call the "parageodetic" distance—which is the elliptical distance on a spherical globe: That is, calculate the angular distance between the two points on the spherical globe, then, staying constrained to the graticule (which, by its origin, is always spherical, thus "graticular"/spherical), find the average elliptical arcradius along that great-circle segment and multiply the two together (in the same way you would multiply the average value of M{Lat} <between $Lat_{1}$ and $Lat_{2}$> by ΔLat to find the distance along a meridian <between $Lat_{1}$ and $Lat_{2}$>). Think of the antipodal case: The geodetic distance will always be north-south, along a meridian, as that is "conformally" the shortest distance (i.e., if you theoretically pulled a string from a point on the equator, along the equator, to the other side, the string would "lift" until it is north-south, when it reaches its antipodal point), whereas the parageodetic distance would be the elliptical distance along any great circle (also known as a "transverse meridian") between and including a common, vertical meridian and the common, horizontal equator. There is a popular geodetic approximation ("Andoyer's Approximation") that is actually a parageodetic approximation!
But I realize that the "parageodetic"—as far as I know—would be considered waaaaay out into original research land, so I'm not attempting to go anywheres near there! P=)
The idea of O{Azg:Lat}/"omniversal"/"transverse neridional" arcradius (at least in some form), however, I don't think is OR (especially if it is presented right). I suspect that it may just be a mostly forgotten concept, given all of the advances in geodetic formulation for finding the "shortest" (i.e., conformal) geodesic. Either that, or P{Aze:Lat} is supposed be the "omniversal"/"transverse neridional" arcradius in some other reference form (e.g, "reduced", "parametric", etc.), with some way to convert it to the more apparent O_e{Aze:Lat}—thus the question to the RD.
As for all of the loxodromic intro, that is meant to be an attempt at presenting O{Azg:Lat}'s derivation. ~Kaimbridge~ 15:46, 30 October 2005 (UTC)

chemical structure of rubber (natural and synthetic)

I have been loking around for the chemical structure of Natural Rubber and Synthetic Rubber but seem to be having no luck. Any webistes or books that anyone knows of and has some information of the chemical structure of rubber would be of great use to me.

Thank you

• Our synthetic rubber article has some info. - Mgm|^(talk) 11:12, 30 October 2005 (UTC)

Latitude CPx Probelms, BSOD and more

This is what happens.

1. Laptop boots up fine, Connects to internet via 56k/LAN modem 2. Laptop runs for a while, then all the sudden, it flickers to a BSOD(Blue screen of death. The blue screen that has Windows error messages.) Then the comptuer instantly shuts down, like a force down, then starts rebooting, and go to the screen, where it checks for fragmentation (Something close to that) If I leave the Laptop off for a while, then i can turn it back on, and it will work fine, then goes back to step 2.

Then soemone told me to clean out the heat sink, and fins of the fan. I did, and i put the whole computer back togeather, and plug it in. I turn it on, and the Lights blink (CAPS Num, Scrool lock)they blink a couple times then it turns off. Nothing on the screen, nada. Did i just screw up my hard drive or something? Any Ideas on what's wrong?

I used to have a similar BSoD problem on my laptop where it would show the BSoD for about half a second and then force-down/reboot. This was nowhere near enough time to capture the error messages displayed. I thought of using a camcorder to record the screen, but the BSoDs were too sporadic for me to catch it. However, Windows did record the technical details to hard disk, and Windows told me it was a problem with a device driver. Further investigation led me to discover that this was my audio driver. My audio driver tends to have problems in other places, too.

So my guess is that there might be a link between your modem driver and the BSoD. And about your second (more serious) problem, well, it's a bit late to tell you this unfortunately, but in general you shouldn't take apart laptops. Even the professionals can make critical mistakes doing it. Everything is very compact and fragile, and it can be almost impossible to put back together a laptop successfully after taking it apart. Desktops are much, much easier because everything is neatly placed and substantially spaced out to fiddle with. It doesn't look like your laptop is even getting to BIOS; the Num, Caps and Scroll Lock lights flash as a basic circuit thing, but it doesn't seem to be progressing. Try pressing/holding F12 while turning it on, this usually activates the BIOS menu on most systems while it's going through. It's worth a try, however, I doubt it would work, and I'm sorry to tell you the news but the future for your laptop doesn't look good. -- Daverocks 13:04, 30 October 2005 (UTC)

Well it may be too late for my poor laptop, but this was a Goverment laptop, and i put XP on it, so how come 1-2 months after i start using, it, it starts having these problems? 69.181.206.232 17:48, 30 October 2005 (UTC)

Seems to be fixed. Had soem error with RAM think it overheated. But either way seems to be fixed.Lordned 19:32, 30 October 2005 (UTC)

October 30

LCD monitor problems

Hello, all. Before I purchased my new laptop, my old laptop was giving me quite a lot of problems. What happened is that sometimes, the LCD display would show some sort of "snow", but differently. If you had, for example, three white pixels aligned horizontally, a magenta pixel would appear next to the third pixel. Also, if there was a black pixel below and left of another pixel, that pixel would appear lime green (my guess is hexadecimal #00FF00). I don't use it anymore, but I've always wondered what was causing the problem. All the connections were properly plugged (I checked them myself several times), and I've heard somewhere that it could have been because of a property of LCDs, but I didn't get more explanations. Is that possible? If it is, what was causing it? Titoxd^(?!?) 03:47, 30 October 2005 (UTC)

Maybe a stuck pixel? Take a look, but it doesn't seem to explain why the pixel is faulty. -- Daverocks 12:09, 30 October 2005 (UTC)

Also, most LCD monitors warn of occasional random pixels, due to limits of the technology. That said, it sounds like your case may go beyond the normal range. StuRat 16:37, 30 October 2005 (UTC)

No, neither one seems to fit this problem. If you switched a window, producing a different combination of pixels, some of the magenta pixels would appear normal, and some of the normal would appear green or viceversa. It probably is one of those cases not covered by the six sigmas. Titoxd^(?!?) 01:06, 31 October 2005 (UTC)

Bridge type identification

I tried this on Talk:Bridge but didn't get a response. Can someone tell me - what sort of bridge is the Tasman Bridge? Concrete arch? More pics here. -- Chuq 04:42, 30 October 2005 (UTC)

I'm not sure about the construction technique, but by the look of it, I think it is a Box girder bridge. smurrayinaHauntedHouse...Boo!^{(User), (Talk)} 09:06, 30 October 2005 (UTC)

Prestressed concrete, including the columns. Not an arch. Do you need more info? --Commander Keane 14:55, 30 October 2005 (UTC)

Let's see...It is a beam bridge (as opsoded to an arch). It's not a box girder, it's I beams, specifically 14 precast, prestessed concrete ones (24 in. wide at the top of each).--Commander Keane 16:21, 30 October 2005 (UTC)

Coloured glass

Inspired by the biology question above, why is it that when I look at a tainted window on the outside it has the same colour as when I look at it from indoors? If the colour on the outside is a reflection of that wavelength, then on the inside I'd have to see white light without that wavelength, so the complementary colour. On second thoughts, I'd have to do this test with the lights out on the inside. Would that be the cause of it, that I see the reflection of the lights inside? But they're much weaker than sunlight, so that sounds unlikely. DirkvdM 07:21, 30 October 2005 (UTC)

Practically, you don't "see" the color of the glass, you see the color of the objects behind the glass. If I wear dark brown glasses, everything I see is tinted in dark brown color. I see dark brown dogs and dark brown cats.

Let's say the sunlight has R-G-B components (highly simplified) and your glass absorbs all green light:

• Case 1: You're inside:

sunlight (RGB) → light hits an outside object (scattering; RGB) → glass → filtered light (RB) → your eyes (RB)

• Case 2: You're looking from the outside to the inside (above):

sunlight (RGB) → glass → filtered light (RB) → light hits an inside object (scattering; RB) → glass (filtered again; RB) → your eyes (RB)

The complementary colour (G) is absorbed. You don't see it. You may see the direct reflct of the sun, but the color of the light reflected from the outer surface of the glass is not necessarily the color of the glass (affected by multiple factors). -- Toytoy 08:42, 30 October 2005 (UTC)

Ah, so it's a matter of absorption in stead of reflection. Makes sense. But where does the energy go? Is it turned into heat (sounds unlikely)? Or, another option I now think of, is the frequency changed? DirkvdM 08:14, 31 October 2005 (UTC)

Under the normal condition, most of the absorbed light energy turns into heat. If you place a blackened steel plate under the tropical sun at noon for a period of time, you can cook an egg on it. The heat in steel transfers to the egg very quickly. If you place a black plastic board under the sun, it will not cook the egg. Moreover, the object can always transfer the heat elsewhere. So the temperature will not rise indefinitely.

However, if you're in a typical living room, the artificial lighting is too weak to heat anything. (Fluorescent lamps: Too little infrared. Incandescent bulbs: Can only heatup nearby things.) If you're in a movie studio, these kilowatt lights can easily burn something if you fail to take reasonable care.

Frequency change is very unlikely if you're not talking about nonlinear optics. -- Toytoy 12:58, 31 October 2005 (UTC)

Or blackbody radiation? User:Omegatron/sig 19:54, 3 November 2005 (UTC)

It should be noted that there are varieties of glass that reflect different colours differently. I have no idea what goes into them, but a local glassware company called Iittala makes various glass objects in a color they call "rose-olive", which looks greenish in reflected light but purple when seen against the light. A reasonably good image can be found at [3] (front left), but the effect is much more striking when seen in reality. In many photos on the web, such as [4], the glass simply looks lime green due to excessive reflected studio lighting. —Ilmari Karonen 16:00, 31 October 2005 (UTC)

• These probably work by selectively reflecting (rather than absorbing) certain colours. If you look at light reflected off the glass, it look one colour, say green. If you look at light through the glass, it looks like the complimentary colour (magenta). Dichroic filters work the same way. You generally make this sort of effect by putting some kind of optical coating on the glass. --Bob Mellish 16:31, 31 October 2005 (UTC)

Statistic on death worldwide, due to Malaria, from an admissible source (WHO preferred)

I am looking for a single figure on deaths worldwide due to Malaria (I believe the figure is about 1 million) from an admissible source, such as the WHO. I've looked on their site, but cannot find a stated figure for 2004 or estimated for 2005. Many thanks! --08:58, 30 October 2005 (UTC)

The first paragraph of the WHO malaria site says "more than one million people...a year." Hope that helps. - Akamad 19:50, 30 October 2005 (UTC)

Thank you! A more specific figure would be cool, but that'll do in the absence of one! Thanks again --19:57, 30 October 2005 (UTC)

Yeah I imagine getting accurate numbers would be difficult, this WHO document (PDF) puts the number of deaths betwen 0.7 and 3 million (page 13). Akamad 02:57, 31 October 2005 (UTC)

Wow - that's great! I can just discuss the difficulty in gaining accurate numbers. Thanks again for your help! --08:06, 1 November 2005 (UTC)

Enthalpy

What is the ΔH_c of Methanol and Hexane? smurrayinaHauntedHouse...Boo!^{(User), (Talk)} 10:24, 30 October 2005 (UTC)

• For methanol, by calculation, I get −726.8 kJ/mol. I don't have Δ_fH for hexane handy at the moment so I can't do the calculation there. You can find measured values at the Linstrom, Peter J.; Mallard, William G. (eds.); NIST Chemistry WebBook, NIST Standard Reference Database Number 69, National Institute of Standards and Technology, Gaithersburg (MD) . Physchim62 (talk·RfA) 16:47, 30 October 2005 (UTC)

Water on Earth

Has all of the freshwater on earth already been drunk before by animals and humans? That is, is all drinking water purified urine? Jazz1979 10:45, 30 October 2005 (UTC)

Nearly certainly, considering that land animals have been around for the past several hundred million (a billion even? Don't listen to me, I'm not a geologist nor a biologist) years. Look at it this way - something that's passed through so many kidneys has to be clean, right? -Sam Pointon 12:19, 30 October 2005 (UTC)

I think the general idea is that life has been on Earth for over 3 billion years -- although most of that time life was just simple organisims like bacteria. Given that idea, I would say that almost all of the water on the surface of the planet has been used by some organisim or another, although probably not by humans (a realitvley young species).

But it's not just your drinking water here, you breath in water vapor with every breath, so you're drinking that ex-urine too.  ;-) --Quasipalm 16:15, 30 October 2005 (UTC)

"You are made of star dust !" - Carl Sagan

"You are made of dinosaur poop !" - Me - StuRat 16:29, 30 October 2005 (UTC)

If there's some water somewhere on Earth that has escaped contact with life (a real eternal permafrost?) then it's quite unlikely that you will get in contact with it. By the way, the purification is most likely done by evaporation; cloud creation over seas > rain over land > your drinking water. But does this mean that all the seas are concentrated piss? DirkvdM 08:22, 31 October 2005 (UTC)

In a way, but things like urea and uric acid are also broken down by other processes in the oceans. That might be one reason for the higher concentrations of "impurities" in the oceans, such as salts, however. I'm not sure if it would be significant relative to the contribution of impurities from other sources, however. StuRat 00:02, 1 November 2005 (UTC)

Most of the salt in the oceans is from rocks and underwater caves that were joined into the ocean, salinating it at some point or another. Most of our salt comes from unadulterated salt mines that haven't joined the main oceans. The salts of living things came from these places and were incorporated by them metabolizing the salts. I think a very, very small fraction of the salt in the ocean came from living things because living things tend to recycle their own substances (human->cow->grass->human/cow/animals/feces/etc). Rarely do other creatures absorb salt and compounds from pure sources.--Screwball23 ^talk 04:24, 2 November 2005 (UTC)

But then where did those salt deposits ome from in the first place? Dried up seas? But before that, where does salt come from? DirkvdM 09:30, 2 November 2005 (UTC)

Salt is a chemical compound with an anion and cation. Sodium chloride is but one of the types of salts out there. Most salts contain a halogen and an alkali metal but think of them simply as a metal and a nonmetal bonded. If you want to know where the salt on earth came from, you must remember that the salt on earth is as old as the earth itself, and was present when the earth was still molten-hot. As for which came first, the salt or the seas, the answer is the salt. The salt chemically bonds faster than a hydrogen-oxygen reaction, so salt was bonded faster from gaseous compounds. The salt was melted into liquid-hot magma and was going around the earth until it cooled. It cooled into a solid and later, water cooled to a liquid, and water naturally dissolved the salt. However, most of that salt was in underground pockets while the water only existed on the coolest surfaces of the earth, so the oceans became more salty as time progressed. The salt-mines are just pockets of salt in our bedrock that happen to be near the surface or were not dissolved by the seas.--Screwball23 ^talk 15:20, 2 November 2005 (UTC)

Carbon redux

For context, see #Carbon, above.

Okay, I'm curious... how is carbon used in dentistry? ‣ᓛᖁ♀ᑐ 13:00, 30 October 2005 (UTC)

I believe dental drill bits are often diamond dust coated. (Note that the article on dental drills didn't exist when I wrote that list, so I decided to just link to dentistry and let the reader puzzle it out. I've since started the article; corrections and improvements are welcome.)

The list actually happens to be quite comprehensive, as it includes three different carbon allotropes plus organic compounds. Probably not what the teacher expected, though. —Ilmari Karonen 13:29, 30 October 2005 (UTC)

I don't have a clue how elemental carbon would be used in dentistry, at least the way it is practiced in the United States. This is a stretch, but some water purification systems in dental equipment may contain activated charcoal filters.

Of course, carbon is part and parcel of all organic life, which pertains to dentistry, as it does to all the health professions. Dental burs ("drill bits") may be composed of carbon steel, and are tipped with tungsten carbide. But elemental carbon? I don't think so... --
Mark Bornfeld DDS
dentaltwins.com
Brooklyn, NY 21:37, 30 October 2005 (UTC)

Laptops and Notebook Computers

Why don't laptops and notebooks have VGA screens?

• What do you understand by "VGA"? Viewed as a standard size in pixels, most laptop computers have a better-than-VGA screen, just like most desktop computers. Notinasnaid 13:44, 30 October 2005 (UTC)

• If you're asking why they have LCD rather than CRT screens, it is because of the size difference between the two. --Fastfission 14:38, 30 October 2005 (UTC)

I get a 1600x1200 resolution on my laptop, which is well beyond VGA. StuRat 16:26, 30 October 2005 (UTC)

The VGA standard resolutions were set forth by IBM and the release of the IBM PS/2 in 1985. The Article VGA Explains the resolutions. VGA is small and old. VGA was superceded by a fast growing industy to be named sVGA. Which, since it was a lot vendors haggling, and bragging, is not so well defined as VGA.

1. VGA (or Cathode Ray Tubes CRTs )screens are heavy compared to LCD or Liquid Crystal Displays.
2. Some early portable computes had CRT displays. ( most notably, the Osborne 1, and the IBM PC Portable, but quickly became obsolute, when the company or competition adopted LCD displays ) Artoftransformation 09:47, 2 November 2005 (UTC)

Spanning tree

Not really sure where to put this but the following anon 84.59.113.235 has created three articles on spanning trees that look like complete gibberish. Can someone expand them into encylopedic stubs? Theresa Knott (a tenth stroke) 17:04, 30 October 2005 (UTC)

How about a link so we can find it ? -> spanning tree. StuRat 20:47, 30 October 2005 (UTC)

Do you mean the mathematics or the network protocol article or both ? StuRat 20:51, 30 October 2005 (UTC)

She meant the articles in Category:Spanning tree. --R.Koot 21:13, 30 October 2005 (UTC)

I see what you mean, those 3 articles do need work. StuRat 21:55, 30 October 2005 (UTC)

I'll see if I can expand them a little after my exam week. --R.Koot 23:23, 30 October 2005 (UTC)

Methane

Hello, this is related to another question I saw on another page. My question is I know that the chemical methane is added to the nicotine leaves to aid in burning. Would the leaves be able to burn or burn well without this chemical and how is it that the smoke doesn't blow up since it is a dangerous chemical when someone lights up? Also, what other chemicals besides methane are added to the niotine leaves not the paper to make it burn and burn slowly?

It has to do with the concentration of methane. Too low of a concentration just provides a nice even burn. At a higher concentration you can get an explosion. At the highest concentrations you no longer get explosions due to a lack of available oxygen, interestingly enough. StuRat 20:42, 30 October 2005 (UTC)

Potassium nitrate is added to cigarette tobacco in many countries to make it burn faster and to make it harder to extinguish. There used to be special cigarettes for sea fishermen which had a particulerly high potassium nitrate content and which were virtually unextinguishable even in a gale! Physchim62 (talk·RfA) 10:15, 31 October 2005 (UTC)

Without the methane and excluding the paper would the dried tobacco leaves be able to burn or are they dependent on the methane to burn?

You can certainly burn tobacco without added chemicals, as smoking predates all those additives by centuries. A pipe was typically used, which retains much of the heat of combustion and offers some protection from wind and moisture which might tend to extinguish the tobacco. StuRat 23:53, 31 October 2005 (UTC)

I thought the Indians used cigars (putting the burning end in the mouth). The thickness of the cigar would probably help in keeping it burning. DirkvdM 09:22, 1 November 2005 (UTC)

What about other chemicals like ethylene or butane are those added to cigarettes and do those also aid in the burning of the tobacco leaves? Also how are these things added, I read about how tobacco companies shred the dried leaves then they add the top dressing as they called it by spraying it on, but that also includes strange things such as chocolate and honey and coffee, how do these things along with the chemicals remain on and not make the leaves soggy and the chemicals not be watered down so they work effectively?

Anything highly flammable would help them burn better. As for getting soggy, the leaves are cured before being made into cigs. One method of curing is to heat the leaves to drive off excess moisture. StuRat 17:46, 1 November 2005 (UTC)

This question goes back to the original question about methane. You mentioned that a very low concentration of methane helps slowly burn without being dangerous, how much would be considered a low concentration and what concentration leve does it get dangerous?

Lungs

What is the anatomical position of the lungs?

In the chest in most of us. If you are writing a xenobiology report for your home planet, you can say that humanoids have lungs within the thorax that take up most of the space within. They are cephalad from the diagphragm and caudad from the neck. They surround the mediastinum. And please emphasize in your report that humanoids taste really bad. alteripse 18:53, 30 October 2005 (UTC)

That somebody doesn't know where their lungs are just takes my breath away. StuRat 20:36, 30 October 2005 (UTC)

<sigh> lame jokes make me gasp Theresa Knott (a tenth stroke) 22:25, 30 October 2005 (UTC)

If you don't think that's shocking, according to the November, 2005 American issue of Playboy, "20% of Americans think the sun orbits the earth. 17% know the earth orbits the sun but think it does so every 24 hours, not every 365 days." No, I don't know where they got their data. Dismas|^(talk) 22:37, 30 October 2005 (UTC)

95% of those who answered everything correctly didn't notice that they are visitors from Europe, Africa, Asia, Oceania or South America. :) Playboy rules! Now give me a playmate. -- Toytoy 06:35, 31 October 2005 (UTC)

I think they got them from the NSF's Science and Technology Indicators surveys. Note the charts to the left; sadly, Europeans don't do significantly better or worse than Americans---more Europeans think lasers work by focusing sound waves, whereas more Americans think that the earliest humans lived at the same time as the dinosaurs. grendel|khan 18:01, 31 October 2005 (UTC)

Bad survey technique. Those guys were distracted by the pictures. alteripse 00:36, 31 October 2005 (UTC)

Still, it was a rather titillating survey. StuRat 23:49, 31 October 2005 (UTC)

With out stupid people there would be no smart people--Eye 22:53, 31 October 2005 (UTC)

Or vice versa. DirkvdM 09:24, 1 November 2005 (UTC)

Integration of Second Derivative

I have that ma=-(k squared)/(x to the third). And you have that a is the second derivative of x with respect to time. I need to fine x of t, x(t). How do I do the integral of a second derivative to get x of t? Confused. Please help.

$ma=-{k^{2} \over x^{3}}$

This is a differential equation, since $a=d^{2}x/dt^{2}$.

Try repeated Separation of variables and integration.

Separated, this is:

— Sverdrup 18:47, 30 October 2005 (UTC)

Actually, I don't think you can apply that trick, at least not easily, for second derivatives. I'll explain momentarily. -- SCZenz 22:42, 30 October 2005 (UTC)

Well, I got distracted, but I'll explain now. First of all, $d^{2}x\neq (dx)^{2}$, but anyway let's try to apply the trick twice and see what happens. We have, with f(x) = -k²/(mx³),

${\frac {d^{2}x}{dt^{2}}}=f(x)$

Thus

${\frac {d}{dt}}({\frac {dx}{dt}})=f(x)$

Which gives

${\frac {1}{f(x)}}d{\dot {x}}=dt$

You might hope that your variables are now separated, but in fact ${\dot {x}}$ = dx/dt is a function of both x and t so they aren't. I don't know of a way to apply the trick to second derivatives. Maybe someone who knows more math than me can comment further. -- SCZenz 07:52, 31 October 2005 (UTC)

Long time since I did this, so almost certainly wrong:

${\frac {d^{2}x}{dt^{2}}}={\frac {dv}{dt}}=({\frac {dx}{dt}})({\frac {dv}{dx}})$

By basic chain rule. So you then have 1/2 m v^2 on one side and the integral with respect to x on the other. Physically, think of it as calculating the kinetic energy gained/lost as you move a distance under a given force. You can then get x(t) by direct integration, if you do some clever square rooting and rearranging.--Fangz

Interesting. Should've thought about it longer, it felt quite wrong actually. I recognize what Fangz does though, that must be how I solved this kind of problem in my mechanics classes. Hmm. I really need to study this a bit more. Sorry for the bad advice. — Sverdrup 19:15, 31 October 2005 (UTC)

This is basically good, but needs a slight clarification...( PLEASE! Someone tell me how to write an intergral sign??!)

If we take that last equation and integrate all parts...

$I2(frac{d^{2}x}{dt^{2}}=$Now I see the problem!

$ma=-k^{3}/x^{3}.a=a(t)m=K,k^{3}=K$

rewrite it as $a(t)x^{3}=(k^{3}/m)$Ahahaha!

Now Integrate all the parts using the varible t. ( Hint: you must substitute for a as fuction of t (See the first hint in this section...)

Apply Fangz trick twice and you'll get the answer straight-away. However, Wikipedia is not the place to ask for assistance for homework problems ... linas 04:28, 1 November 2005 (UTC)

Well, wikipedia isn't the place to get people to do homework for you. But I don't think there is anything wrong with people discussing homework problems here, so long as you understand any ideas suggested, not just copy down the answer wholesale. If it's just discussing approaches, then it's part of the learning process, and there is nothing wrong with that. It's identical to asking your teacher for a hint, asking schoolmates, or looking up material in the library or a textbook.--Fangz 17:43, 1 November 2005 (UTC)

global warming

why is the % of carbon dioxide in the atmosphere so small?

Take a look at the article Earth's atmosphere. The atmosphere was primarily composed of carbon dioxide and water vapour. As the planet cooled, the water vapour condensed into oceans and seas, and the water in turn dissolved most of the carbon dioxide. The evolution of photosynthesizing plants resulted in further reduction in CO₂ levels. -- Canley 22:31, 30 October 2005 (UTC)

Long ago the evil chloroplast-bearing plants took over the earth and consumed all the CO2, emitting all this corrosive oxygen. If we all breathe hard enough, maybe we can reverse this state of affairs, lower the O2 level, and raise the CO2 level again. alteripse 03:28, 31 October 2005 (UTC)

No worries, we've already invented cars to do that for us. Aren't we clever? DirkvdM 08:35, 31 October 2005 (UTC)

In addition, in case you are wondering, the significance of this with regards to the current global warming situation is that we don't need to worry about destroying the world, or indeed all of life, only ourselves and our current civilisations.

Indeed. Destroying the Earth is harder than you may have been led to believe. grendel|khan 18:08, 31 October 2005 (UTC)

That's about destroying the Earth as a planet. But even 'just' destroying all life on Earth would be a job that's way beyond the present capabilities of mankind. There's always at least some bacterium that will survive, from where things could start all over again. But even exploding all available nuclear weapons (strategically placed, with this purpose in mind) would constitute little more than a major blip in the evolution of life on Earth, I assume. It would take much less to ruin things for ourselves, though. And not just for our offspring, but also for our generation. An increase of the average temperature with a few degrees is expected for the not too far future and if you look at a map of the average temperatures on Earth, that would mean habitats shifting towards the poles by hundreds or thousands of kilometers. At least, the temperature bit of the habitat. Other aspects of the habitat will likely not be found at the new location, so many species will get extinct. This sort of thing has happenend before, but never at this speed. Evolution takes time and most species cannot adapt that fast. Mankind can help where foodcrops are concerned, but the adaption will also take time - eg farmers need to learn about new crops, also in poor countries where spreading the needed info will not work very efficiently. So mass starvation will result (which will also affect those safely in the West). The again, if those farmers in poor countries would get the help they need to survive, that might give those countries the boost they have needed for so long. But I wouldn't count on this happening. Also, local temperature change may (and often will) be much greater than the world average. And temperature change is just one thing. Rainfall patterns will also change. Everything will get messed up. Globaly and at an incredible speed. Be afraid. Be very afraid. DirkvdM 09:40, 1 November 2005 (UTC)

Hospital

What is a hospital district?

• It's the district covered or serviced by a hospital. So if were sick or injured in the Union County Hospital District in Illinois, you would be taken to the Union County Hospital. -- Canley 05:02, 31 October 2005 (UTC)

October 31

Solution

How do I find the mass of a solution given the mass of the solute?

You need the concentration of the solution. Perhaps molarity or molality, depending on what the homework problem is asking. Titoxd^(?!?) 02:19, 31 October 2005 (UTC)

You also need to understand the principle of conservation of mass. Note that volume is not conserved. Physchim62 (talk·RfA) 10:18, 31 October 2005 (UTC)

I don't think it is entirely certain that mass is conserved when something is dissolved. In most cases, probably, indeed I expect that's what our questioner requires, but what if you are trying to dissolve calcium carbonate in a weakly acidic solution?--137.205.18.131 13:57, 31 October 2005 (UTC)

Remember that mass is conserved in a closed system - in this case you need to take into account the liberation of the carbon dioxide. If you don't, well, obviously mass isn't conserved. --216.191.200.1 14:18, 31 October 2005 (UTC)

"For every chemical problem, there is a chemical solution." - StuRat 02:44, 1 November 2005 (UTC)

UTS of indented prestressing steel wire

As per different standards of indented prestressting steel wires, it is seen that as the diameter of wire increases Ultimate Tensile Strength (UTS) decreases. As an example minimum UTS of 4mm dia wire is 1715 N/sqmm while that of 5mm dia wire is 1570 N/sqmm.

When enquired from different manufacturing agencies, it is learnt that while drawing from same parent material, by cold drawn process, Breaking load decreases which is not in the same propotion as that of diameter. Since UTS = Breaking Load/Area, it varies.

Why the Breaking Load of these steel wires does not decrease in same propotion as that of diameter of the steel wire? Is there any molecular changes involved in it, if so what is that?

MALOY NANDI

It's not directly related to the diameter. Nor is there any kind of molecular change cause by an increase or decrease in diameter. See Strength of materials, and also check out Solid Mechanics on the Wikibooks site. Proto t c 09:53, 31 October 2005 (UTC)

Then why does UTS decreases with increase in diameter of Plain Drawn Steel Wire?

MALOY NANDI

It's to do with its Young's modulus, and the relationship of stress and strain. The relationship is different for every material. Read the article on the Wikibooks site. Proto t c 12:30, 31 October 2005 (UTC)

From the Australian Standards, the brekaing load for 7mm and 5mm wire is proportional to diameter squared. Also, the 7mm wire has a higher UTS than the 5mm wire. Are you sure you are just talking about wire and not strands and bars? I'd like to discuss this further.--Commander Keane 18:05, 31 October 2005 (UTC)

As per Indian Standard Code (which are practically photocopy of British Standard), minimum Ultimate Tensile Strength (UTS) of different sizes of steel prestressing wires are as following –

Dia of wire UTS (N/mm2)

• 2.5 mm 2010
• 3.0 mm 1865
• 4.0 mm 1715
• 5.0 mm 1570
• 7.0 mm 1470
• 8.0 mm 1375

It is seen from above table that UTS of a plain drawn steel wire decreases with increase in diameter of the wires. What is the reason for this variation if parent material remains same, with no change in chemical properties?

It is understood from the discussion with different manufactures (TATA Steel), during cold drawing process Breaking Load decreases, but not in same proportion, with decrease of diameter of wire. What is the reason behind it and what changes are taking place within the hard drawn steel?

MALOY NANDI

I don't know mate. I'll look into it, but it might take me a couple of weeks. I agree that your values closely match the Australian Values (although we have some variation, ie we can have 7 mm wire with UTS of 1800 MPA or 1870 MPa or 1950 MPa.) My guess (which might be wrong) is that the larger (surface area)/(volume) ratio for smaller wire allows better cooling of the wire during manufacure. The larger diameter wire has a smaller (surface area)/(volume) ratio - and the steel in the middle of the wire stay molten while the outer steel is already cool. This creates internal strains which reduce the strength of the wire. Only a guess though. --Commander Keane 06:35, 3 November 2005 (UTC)

There is no heat process involved in cold drawing process. Larger dia wire (e.g. 8mm) is passed through various dies of smaller diameter to get smaller dia wires (e.g. 4mm/5mm etc.). Resultingly UTS of wire increases.

MALOY NANDI

I give up. You can try emailing someone at your nearest university.--Commander Keane 16:25, 3 November 2005 (UTC)

Electron mass

I understand the electron mass is the best measured particle mass, to an accuracy of some 10 digits. I am wondering if there have been any attempts to test whether the mass is in fact a constant, or if it is changing over time (if the mass changed significantly over cosmological times, there could conceivably be a change in the 10th digit over a few decades or so). And, which property is actually measured in this precise number of e mass: is it the relation to the proton mass? Which definition of the kg is intended when they say m=0.510998918(44) MeV/c**2 ? Would a change in elementary particle mass that leaves the ratio of e to p masses intact even be registered, or would that be equivalent to a change in the gravitational constant? Baad 08:12, 31 October 2005 (UTC)

The accuracy of the measurement, according to the particle data group, has improved by a factor of 5 since 1999 and by a factor of 50 since 1987 [5]. Thus if there were changes in those last few digits over decades we wouldn't have seen them. All the measurements listed since 1987 are easily consistent within 2 sigma (i.e., close enough that they don't indicate any inconsistency), and presumably before that even fewer digits of precision are available.

The most accurate measurements are made relative to the mass of a carbon-12, which is defined to have a mass of 12 atomic mass units. The measurements in electron volts are less accurate, because the conversion involves the elementary charge, which is not as accurately known as the masses themselves. Proton mass measurements are independant and have the same limitation [6]. They're not measuring the electron mass over the proton mass at all.

As for your question about whether a change that kept the ratio intact could be registered, that would depend on what else changed—assuming all particle masses scaled in the same way but other laws of physics left intact, the changes would still register because some of the mass in carbon-12 is determined by the nuclear binding energy (and thus by the nuclear force), so its mass wouldn't scale in quite the same way as the proton or electron. (In fact, if you only changed the masses of elementary particles, the proton mass wouldn't change much at all, because almost all of its mass comes from the strong force and not from the masses of its constituent quarks.) Let me know if you have more questions. -- SCZenz 08:37, 31 October 2005 (UTC)

interesting... but, on second thoughts, I assume changing e or p masses are not an issue anyway, since they would register in the H/He emission lines of ancient galaxies? Or are these independent of particle mass? Baad 09:05, 31 October 2005 (UTC)

They depend strongly on the electron mass, but only a little on the proton mass. -- SCZenz 09:09, 31 October 2005 (UTC)

ah, but on third thoughts, since the known 'contemporary' frequencies are presupposed to estimate the Hubble constant, that's not true; if the masses changed, we'd be wrong about the age of the Universe, but we couldn't tell. Baad 09:14, 31 October 2005 (UTC)

There's more than one source for the age of the universe; having something odd like that screw up our ideas without us realizing it would be very difficult to set up in a self-consistent way. -- SCZenz 09:19, 31 October 2005 (UTC)

well, the age of the Universe is certanily not known to ten digits' accuracy :) so if the mass of the electron changed, say, 10% over the last ten billion years, I doubt that we would be able to detect it. Baad 09:53, 31 October 2005 (UTC)

The problem is that electron mass is tied up with a number of other things - according to certain theories, it is a result of deeper principles. (maybe. I'm fairly uncertain here) Even the possibility of electron mass changing would mess up a great number of things. --Fangz 20:52, 31 October 2005 (UTC)

If I got this correctly, nobody has an inkling of why particle masses are what they are. People have ideas of why they are massive at all, but no known principle would prevent an electron to have a mass of 0.6 instead of 0.5 MeV. The whole particle zoo is completely descriptive, even the three 'generations' are unexplained, for all we know (I think...) there could be five or nineteen. particle masses shifting over time would thus in a certain sense be a relief, because it would rid us of the obligation to explain their seemingly random values. We would of course have to come up with an explanation of why and how they shift. This is, at least, what you get from the Standard Model. I have no idea what sort of advanced ideas may be brewing in GUT territory. 23:31, 31 October 2005 (UTC)

Indeed, these are all open questions. There are also a lot of theories between the Standard model and Grand Unified Theory, such as Supersymmetry, large extra dimensions, and technicolor (physics). Most of them don't explain why particle masses are what they are, although String theory has a mechanism for doing exactly that—if only they could calculate anything, and find which string theory to use! ;)-- SCZenz 23:50, 31 October 2005 (UTC)

I vaguely remember reading about some confusing atomic spectral data from extremely distant quasars (unresolved distant galaxies) indicating that the fine structure (or hyperfine structure??) structure seems to have changed, as compared to what it is in modern times. I don't know if other astronomers confirmed this or not, and am not clear of what the other interpretations are. However, changing fine structure indicates that either the electron mass or the electron charge or both are changing. Theories to explain this will be all over the map; it will be at least decades if not half-a-century to narrow things down for "extreme physics" questions like this. FWIW, the variation of Kaluza-Klein theory as practiced by Paul Wesson et al. has masses changing by about 10% over about 10 billion years. Here's the fun bit: in their theory, the origin of mass is due to geometry of the 5D KK space, and all sorts of funny things result: for example, mass change is equivalent to Hubble expansion. Note also, changing fine-structure consts does change biochemistry, among other things ... linas 04:45, 1 November 2005 (UTC)

I am intrigued that the order of magnitude you quote (10% over about 10 billion years) should correspond verbatim to what I've forwarded for the sake of argument above.... Anyway, I suppose your quasar article is what I was looking for, so if you have the reference, please let me know. I'd also be interested in the "mass change is equivalent to the Hubble expansion" reference. Baad 12:37, 1 November 2005 (UTC)

Enzymes

Why are enzymes inactivated at low temperatures???

See enzymes. Proto t c 09:41, 31 October 2005 (UTC)

Enzyme activity depends of kinetic energy and the movement of molecules. At low temperature there is less movement and less enzyme activity. If you totally prevent molecular movement you can stop enzyme activity. Sadly, neither the enzyme article nor even the Enzyme Kinetics article describes the effect of temperature on enzymes activity. There is a tiny bit at Rate of enzyme mediated reactions. Here is some more information (about half way down the page). A few more details. --JWSchmidt 14:22, 31 October 2005 (UTC)

Flu jab

Why can't you take the flu jab when you are sick?

Because it gives you a very mild case of the flu, and if you're already sick, it can be exacerbated into a more serious case as your body's defenses are weakened. Proto t c 09:43, 31 October 2005 (UTC)

Not quite. For most people, it doesn't make you sick. The two reasons are (1) liability and safety, and (2) the theoretical concern that effectiveness may be reduced. If a person is sick, he can be sick in many ways and there are many different outcomes (from full recovery, to complicated illness, to death). Although it is extremely unlikely that this type of intervention would change the course of a current illness, the doctor caring for the patient and the person or organization or corporation providing or making the flu shots do not want another variable added in to the illness and especially do not want the flu shot blamed for the outcome of the illness. A lesser reason is that during the acute phase of another viral infection, the immune response to a flu shot might be altered in such that the long term protection response may be lessened. This is mainly a theoretical concern and has not been proven or even well-studied. alteripse 12:17, 31 October 2005 (UTC)

I assume that "flu jab" is a British term meaning influenza vaccination. Some anti-viral vaccines contain active viruses - almost always a virus strain that does not cause illness. Other anti-viral vaccines contain inactivated virus or purified viral proteins. The purpose of flu vaccination is to expose the body to flu virus proteins that will stimulate the immune system to protect the body against future infection by flu virus. Generally, you want to be vaccinated several weeks before being exposed to a flu virus that could make you get sick. Once you have the flu, your body is already being exposed to the proteins of the flu virus and your immune system is responding to defend you. Adding a flu vaccine to your body would not be of any significant additional advantage. The flu virus that is making you sick is itself acting like a very efficient vaccine in the way it stimulates your immune system. The problem is that it takes about a week for your immune system to respond enough to win its battle against the virus infection. If you were vaccinated before being infected by a flu virus, then the immune system of your body will contain things like memory B cells that will make it easier for your body to react quickly to defend against the infection. --JWSchmidt 13:58, 31 October 2005 (UTC)

Chlorophyll

Why is chlorophyll green in colour??? I mean why it has to be green to be able to absorb light?

(From the article) Chlorophyll absorbs mostly in the blue and to a lesser extent red portions of the electromagnetic spectrum, thus its intense green color. This applies to plant chlorophyll. Chlorophyll does not always have to be green - there are also purple bacteria, which use bacteriochlorophyll, which absorbs infrared light. Proto t c 09:48, 31 October 2005 (UTC)

The long answer is that (a) it absorbs more or less the right band of energy - the green colour is light that is not absorbed, and well, green light isn't very common on earth, (b) it coincidentally works chemically with photosynthesis, (c) it just happens to hold the right balance between cost of synthesis and and efficiency for most plant life, and (d) it happened to be picked early on by evolution, and there is no real selective pressure to change it. At least, that's my not-very-rigorous opinion. --Fangz

Light in the green wavelength is exactly as common as light in any other visible wavelength. Tempshill 22:15, 31 October 2005 (UTC)

1) "it just happens to hold the right balance between cost of synthesis and and efficiency for most plant life" This does not sense as far as i can tell. If the cost is the synthesis of chlorophyll, and it can absorb many photons, why is the efficiency relevant?

2) it happened to be picked early on by evolution, and there is no real selective pressure to change it. This does not seem right either. There are accessory pigments in plants that are not green. Carotenoids and xanthophyls are red and yellows, hence the autumn colours. It seems evolution has and does use other variations if needed. Also chorophyll a and b have different, non overlapping absorbtion spectrums suggesting that the absorbtions characteristics are not fixed and someone has already mentioned the bacterio chlorophylls that are purple and absorb mostly in the infra red ONLY. David D. (Talk) 22:46, 31 October 2005 (UTC)

In fact, green light is, in a sense, more common than other colors. The peak of the sun's black-body spectrum, around 500 nm, is in the "green" range, although the sun emits enough light at other wavelengths to make its apparent color yellowish white. —Ilmari Karonen (talk) 01:07, 1 November 2005 (UTC)

Well, these are just my guesses. If you lot have better ideas, I'm happy to hear them.

This does not sense as far as i can tell. If the cost is the synthesis of chlorophyll, and it can absorb many photons, why is the efficiency relevant?

Evolutionarily, the plant is solving a cost-profit problem. Suppose a 'better' pigment would cost X more in terms of energy, and resources (e.g. minerals, water...), but help the plant absorb a higher proportion of photons, and so a higher proportion of light energy. The plant evolutionarily 'chooses' depending on whether the gain outweighs the cost. It may just happen that for the majority of environments, chlorophyll is simply the best solution.--Fangz 02:18, 1 November 2005 (UTC)

Or it may simply be that photosynthesis is a hard problem. There are very few basic types of photosystems in use on Earth, and at least all the really good ones appear to have evolved from a common ancestor. It may be that, in the time life has existed on Earth, green just happens to be the best evolution has been able to come up with so far. —Ilmari Karonen (talk) 10:38, 1 November 2005 (UTC)

The only cost/benefit that I can think of does not relate to the chorophyll. Each photosytem that absorb photons has hundreds of pigment molecules, including carotenoids. Photons absorbed in the spectrum transfer energy to the reaction center and excite the electron to an electron acceptor molecule. Since one reaction center has coopted many pigments it is rare that the supply of electrons is so limited that even the green light has to be harvested. There are exceptions such as shade tolerant plants that see a few speckles of sunlight, their leaves are often very dark green (almost black). Their existance would argue that the need for more photons is not limiting full sun plants and hence losing the green photons does not enter the cost benefit analysis. The only cost I can think of for absorbing green is that the plants heat too much from the inefficient transfer of energy to the photosystem reaction center (energy is lost as heat which is bad for a leaf). However, if that was a real cost it would be the blue end of the spectrum a plant would want to reflect since those photons are higher energy than the green photons. In fact, some plants do have waxes on their leaves to reflect blue light to reduce the heating. In summary, the best argument for a cost benefit argument is the overheating problem from harvesting too many photons but this seems to relate to the plant as a whole NOT to the synthesis of chlorophyll. In general there is no need for a better pigment as there are several pigments than can be combined to adjust the total absorbtion to suit the plants specific environment. David D. (Talk) 12:21, 1 November 2005 (UTC)

• Let's not forget that it is entirely possible chlorophyll is not the optimal solution. It may be that this is not what works best, but what has worked well enough for life to evolve to this point. Evolution is an ongoing process, so it is entirely possible that something may replace chlorophyll as the dominant plant photorecptor someday. Johntex\^talk 20:27, 3 November 2005 (UTC)

Water

Does water/moist conditions promote hair growth?

No. Unless it contains a lot of testosterone, and you drink it. Proto t c 09:44, 31 October 2005 (UTC)

Perhaps what you are thinking about is the lengthening of hair. Hair does seem to become longer when it is wet or humid. It doesn't grow or become longer, it only stretches temporarily.--Screwball23 ^talk 04:29, 2 November 2005 (UTC)

hair

What is the purpose of pubic hair growing around the reproductive organ of both man and woman?

See puberty and pubic hair. Proto t c 09:44, 31 October 2005 (UTC)

I would say two purposes:

Lubrication. Places where rubbing occurs could lead to abrasions. Hairs reduce the friction. To test this, rub two hands together, then put some hair between them and rub again. It should be easier afterwards. Armpit hair serves the same purpose.

Age marker. Body hair is a way to mark that a person is of reproductive age, which is an important thing for any species to be able to distinguish. This explains why young children don't have body hair. Of course, there are many other age markers as well.

StuRat 16:59, 31 October 2005 (UTC)

I would have to disagree with the lubrication remark. There are fluids both the male and female body release to accomplish lubrication. We might call it pre-ejaculatory fluid. Therefore StuRat, I believe your friction argument has no bearing here. As for it being an age marker: that's just more of an unrelated side-effect. In my opinion it has more to do with heat loss. One reason why the hair on our heads has remained throughout evolution has to do with the fact that we lose a large amount of heat out of the top our heads. This is one reason why beanies are so effective. I think this point carries over to our genitals as well. Also, major arteries run through the armpits out into the arm, so I believe my heat loss argument also applies to armpit hair. Remember, at one point in time our ancestors were completely covered in hair, even at birth. Once we started wearing animal furs/clothes to endure the ice-age and the cold northern winters, over millions of years body hair became more of a nuisance rather than a nessecity. It is possible that in another million years or so our bodies will be completely devoid of hair. So long story short: it is simply a way to minimize heat loss. - Cobra Ky (talk, contribs) 19:41, 31 October 2005 (UTC)

I don't believe in the heat loss explanation - if that was true, then an external scrotum and pubic hair would work at cross purposes. Everything2 has an explanation - which you may or may not decide to trust. http://everything2.com/index.pl?node=pubic%20hair --Fangz 20:48, 31 October 2005 (UTC)

Well, reading more into it, there are several resources that confirm the friction argument. But there are also just as many resources that confirm the heat loss argument. Here is just one. Which surprises me that there is no mention of it in our wikipedia article on pubic hair. But there is mention of heat loss in our hair article. My opinion still stands, but I do retract my statements about the friction argument having no bearing. - Cobra Ky (talk, contribs) 20:58, 31 October 2005 (UTC)

This is hearsay, but I recall an American Red Cross pamphlet on survival swimming that claimed the places on the human body where most heat loss occurs are the head, armpits, and groin. Human hair in those locations might be particular to the insulation property of hair. Tempshill 22:13, 31 October 2005 (UTC)

Still, the importance of hair on the head is much greater because it contains the only vital organ outside the torso. And it's not even covered by any substantial amount of fat, so, if it's cold and the head is not covered, loads of heat is pumped up there to prevent instant death. "If your feet are cold put on a hat". It's true, I've tried it. Then again, survival is evolutionary pointless if you dick freezes off (ouch!). DirkvdM 09:55, 1 November 2005 (UTC)

That last mentioning about a frost-bitten penis isn't really very helpful. If heat around the penis was very important, you might have seen hairy penis shafts. Or better yet, hair around the urethral orifices. That would definitely contain heat. It would also create more infections and would lead to wet, cold hairs. It might also create much displeasure during mating. That is probably disgusting to many people, demonstrating that the sexual selection involved would probably be enough social stigma to avoid sexual reproduction of that individual. The heat loss of the penis is great considering that it is an appendage out of the main body, open to the environment, much like a finger. The pubis is actually above the penis, making it very useless for most heating. The testicles, alternatively, favor cold temperatures for maturation of the sperm, leading to the re-thinking of the heat argument. Why would they have hair if heat loss was so important?

The heat loss around the armpits and hair are very good answers, but thinking alternatively, the reason there is so much more heat loss in a pool from these locations would be because the hair causes a build-up of heat.

The reason why we have heat loss may not be the reason why we have hair, it may be that because we have hair, we have heat loss in these regions. We have a great amount of heat loss from many parts of our bodies, but these regions are naturally areas of great heat loss. The brain uses 20% of our metabolic energy. That creates a great amount of heat to be lost, especially in cold weather, when it could easily be contained. The head encapsulates and protects its heat through the use of hair, so I will concede to that, agreeing that the head loses much heat and has hair for that reason.

Secondly, the armpits have hair--and are in a very active joint, so they do have a great amount of hair loss, but they also have large sweat glands. Those regions sweat profusely, showing that they do not need that heat. If they needed the heat, why would they have such large sweat glands? The reason we have large sweat glands (sweating is everywhere) in that area would probably be because the area is a joint and needs to reduce abrasion and could use further lubrication. We could have great friction and would have to callouse the skin around our inner arms in order to function with active arm movement if no hair was there.

The same goes for the pubic hair around the groin. If humans didn't have all that pubic hair around their groin, they would have rough friction between their legs and worse still, their private parts. Consider what friction there would be if a human male had no hair on his scrotum. The constant rubbing against the legs would cause enormous damage, torsion, scraping, and extreme heat in that area. So remember guys, that hair is a God-send. The hair is vital to avoiding friction and creating lubrication in joints, but is not necessary for the head, as it is not a joint but a region of great heat loss. In answer to the criticism, "well, the groin has a great amount of hair and it is losing a lot of heat", I must remind you that the reduction of friction reduces heat too. A joint without hair is a hotter one, disproving the heat loss argument.

The best reason for the pubis we know of at puberty would probably be sexual selection. It demonstrates maturation just as beard growth for males or breast growth for females.--Screwball23 ^talk 02:41, 4 November 2005 (UTC)

Note that the age marker theory is the only one which explains why children lack such hair. Heat loss is actually more of a problem in children, due to their higher surface to mass ratio, so hairiness in children would be a widespread trait if the primary purpose of body hair was heat retention. If body hair was primarily for heat retention we would also expect far more in ethnic groups native to colder climates, and little or none in those native to tropical climates. Also note that facial hair in men is both an age marker and a gender marker. As for the lubrication theory, I wasn't only talking about during sex. Legs rubbing against genitals during walking could produce a rash if no hair was present. Underwear somewhat reduces this problem, however. StuRat 23:38, 31 October 2005 (UTC)

The theories StuRat made were right. Everyone else is thinking too much about the modern-day. There is no real convenience of having pubic hair in your pants rubbing comfortably. How can that convenience evolve? The reason we have hair around our genitals is most definitely sexual selection. No matter what conditions, whether you are blind, in the dark, or messing with someone of the same sex, you can feel the genitals, see/feel the pubic hair and know "Aha! This is a woman! -Then- Aha! This is a mature woman!" If you know that your sexual partner has pubic hair, that person is also capable of having sexual intercourse for the purpose of procreation. In terms of evolution, it stayed because it is necessary for that purpose. Early humans might have mated with younger immature individuals to no avail and produced no offspring. Those that did find the pubic hair did get a good shot at reproducing. If an individual has no pubic hair today, you know that they are incapable of having children because they lack the inherent hormones to begin sexual reproduction. The abrasion theory works perfectly because the groin is a very dynamic pivot point. Movement is going on between all the muscles and joints in the groin. The abrasion is very common and relief must come from hair and sweat glands, of which there is more hair.--Screwball23 ^talk 04:14, 2 November 2005 (UTC)

Does trebble cause more hearing loss than bass?

Which causes more hearing loss, high-pitched or low-pitched sounds? Or, does it not matter? I recently bought earphones that have much more pronounced trebble, but the other night I had ringing ears after using them for an extended period. It made me wonder... --Quasipalm 14:11, 31 October 2005 (UTC)

It depends on how you measure it:

• An equivalent decibel loudness will cause equivalent damage.

• An equivalent energy will cause more damage in the treble range, since treble sounds require less energy per decibel to produce. This means the same energy range will provide a louder sound in the treble range.

You may be encountering the second problem. I suggest you use the equalizer to turn the treble down/bass up to counter this tendency. StuRat 15:43, 31 October 2005 (UTC)

Moreover, be very careful with earphones. It is very easy to set the volume too high. If you already get an instant effect (the ringing ears), then imagine what will happen if you use them regularly all your life. I imagine you might eventually go deaf (to some degree). Earphone#Dangers mentions this but is not specific about the volume levels required for permanent deafness. DirkvdM 10:28, 1 November 2005 (UTC)

Thanks for the replies. I read a bit about the actual levels required for hearing loss on Hearing_loss#Noise_Exposure. I usually use my earphones on the subway -- they are closed-air so they block out the loud trains, so I figure it's a wash.  ;-) --Quasipalm 14:25, 2 November 2005 (UTC)

"treble sounds require less energy per decibel to produce"

Since when? User:Omegatron/sig 19:58, 3 November 2005 (UTC)

axiom of regularity

The axiom of regularity

Axiom of regularity (or axiom of foundation): Every non-empty set x contains some element y such that x and y are disjoint sets.

Disjoint: Maths (of two sets) having no members in common (Collins Dictionary)

This makes no sense to me. How can x and y have no common elements if x contains y. Surely y is a common element.

Danny Ryan

See our article at Axiom of regularity. It really means alot less than you think it does. As a set, x and y share no elements. (If you choose the right y) I.e. y doesn't contain some element that is already contained in x. Which, in a simple set, is fairly obvious if y isn't itself a set.--Fang

Consider the set x={ {1,2} , 3}. x contains two elements, 3 and {1,2}. Both of them are disjoint with y, since they contain no common elements. {1,2} contains 1 and 2, while x does not. 3 is a number and so doesn't contain any elements. According to regularity, all sets work like this. For an example of a (hyper-)set that does not satisfy regularity, consider z={{{{....}}}}. Note that z={z}, so the set and its element are not disjoint. Regularity ensures that sets don't have infinite nests of subsets. -Lethe | Talk 15:25, 31 October 2005 (UTC)

physics

how do i get contacted with physics sicentist so that i can solve my queries regarding physics problems. i am pursuing my phd in this field and i want answers that i am facing it difficult to be answered. — Preceding unsigned comment added by 202.92.68.98 (talk • contribs) 08:36, 31 October 2005 (UTC)

are you serious? You are pursuing a phd in physics, and you are not in contact with any physicists? that sounds pretty hopeless to me. 83.77.216.101 15:40, 31 October 2005 (UTC)

If you are serious and not an advocate of an original theory (the world abounds with people claiming to have proven Einstein wrong, etc.), you may be more likely to receive a response if you establish a username and say more about yourself. -Walter Siegmund 16:15, 31 October 2005 (UTC)

Why don't you post a query now? Dominick ^(ŤαĿĶ) 16:05, 31 October 2005 (UTC)

If you really are pursuing a PhD in physics, try a faculty advisor. You can also try posting the questions here. StuRat 16:40, 31 October 2005 (UTC)

I happen to be a physicist, and I check this page and answer questions regularly. Since I'm only pursuing my Ph.D. in this field myself, if you manage to really stump me I can ask my advisor, a noted physics scientist. So you've made your contact already, and you should post your questions! :) -- SCZenz 07:07, 1 November 2005 (UTC)

You could also solve the physics problem: What is the orbital proximity of Persons at State and National Universities, with PhDs. Start with a list of the 10 closest State Universities. Find their Faculty online. Check which ones have PhDs. ( I would recommend not contacting Professors Emitrius. ) Make a comprehensive list of the closest 25 Phds in Physics. Email them one by one for the most of a month. My College Physics professor said "If in order to make progress we must leave reality, by all means LETS LEAVE REALITY." -Stephen Brooks, Diablo Valley College, Pleasant Hill, CA. He had the red books, i.e. Richard Feynman's Lectures on Physics . Find a local library and spend a few weeks on reading the books. I am certainally glad I did, and I am impressed by the way that Wikipedia has presented both of these articles. You can also post your problems here, so that the last poster and I can quibble over the answers, and make them as clear and easy to understand as possible. Artoftransformation 08:58, 2 November 2005 (UTC). ( Note: after 4 minutes of viewing SCZenz page, I could just walk over to Southside and have a RootBeer with him. From his diagram of the Higgs boson...If we disagree, Id recommend you believe him. )

Charles Darwin and Edward Blyth?

Doing some reading on talkorigins.org led me to trueorigins.org and a few of their articles. There seems to be a creationist idea that Darwin nicked the idea of natural selection from Edward Blyth, who was a creationist. I ask because the Wikipedia article on Blyth (see above) mentions this. How legit is this? I hesitate to believe a darn word the creationists say, which is why I bring this up. grendel|khan 18:13, 31 October 2005 (UTC)

Darwin was certainly influenced by creationists like Blyth (here is a website that claims Blyth as a creationist). However, the challenge would be to point to a published article that existed before those of Darwin and Wallace that coherently expressed the idea of a fundamental role for natural selection in the origin of new species. Blyth wrote things like, "The original form of a species is unquestionably better adapted to its natural habits than any modification of that form." (see) Darwin was able to escape from this kind of thinking about species as fixed forms. --JWSchmidt 18:53, 31 October 2005 (UTC)

Darwin wans't quite the first to come up with the idea of evolution, he just wrote a book about it that really got the discussion going. Not surprising considering how obvious evolution is if you just look around and use your brain. Actually, Darwin's father was a Darwinist avant la lettre (which is of course a strang way of putting it because he was also called Darwin :) ). By the way, evolution doesn't preclude creationism. DirkvdM 10:34, 1 November 2005 (UTC)

I wonder exactly what you mean. You made a statement that was extremely arrogant and it simply doesn't make sense. You said that "evolution [is obvious] if you just look around and use your brain." which is very arrogant and foolish. The first is that you make it seem as if you looked around and discovered evolution. You didn't. You sat back and listened to a teacher tell you what you know and never thought twice about it. It probably didn't change your schema of the world drastically and was never even observed with great consideration. You say evolution is obvious. The answer is that it is obvious NOW. We now have the hindsight to see millions of tons of fossils and a large amount of documented speciation links through genetic populations across the world. We have large numbers of scientists who identify the most minute details of species and were able to find that speciation was more than just a hunch. These were serious scientific works and now you state arrogantly that "uh-duh! It is so simple!" but in fact, it took a great amount of proof across species. We have the good fortune to have verifiable proof through the works of Darwin to apply what we learned from the breeding of pigeons to the geographic isolation and subsequent changes in animals to large species, including ourselves. Humans had been breeding animals for as long as they domesticated them, and I'm sure you probably never even thought how those breeds were differentiated from their ancestors.

The reason I must focus on your statement is that there are too many people who use science, which is supposed to serve 'as a candle in the dark' or 'the absense of an ideology' and turn it into a dogmatic subject. That is the reason why creationism is striking itself in so many places. People simply don't understand evolution well enough to fend off the creationists or at least explain their knowledge. When that is coupled with arrogance, people fight creationism with great force but little reasoning. They simply say "use your brain" when they didn't and create a dichotomy of ideas, both of which are completely founded on faith, of which neither one has much scientific thinking behind it.

The reason why creationism (as we know it) originated is because after the Origin of Species, where Darwin really did his good work in explaining how species evolve, he went on to write the Descent of Man, which was not a very popular read for many people because it was founded on less solid evidence, less fossils, and finally, because it ashamed the human race to be known of as the descendants of monkeys. That sparked the controversy. The Origin of Species was subsequently looked at as a work of nonsense because it angered many to know that they were evolved from apes. The culture shock took time to come to grips with, but evolution is the more prevalent theory now. The other reason why evolution of humans was solidified was because scientists got more fossil evidence, so people "used their brains", went out there and proved it. I doubt you did any of that. The main reason why creationism is going up now in American classrooms is because the theory is not being taught well enough and people do not think twice about their positions. If people "used their brains" they would use proof and not just accept things, avoiding the whole "debate" (which is purely political, not scientific).

Don't accept things as "obvious". Use your brain.--Screwball23 ^talk 15:57, 2 November 2005 (UTC)

This is a spinoff from the main thread. Below is an earlier entry of mine in which I stated that I used the term creationism when I really meant creation (so "evolution doesn't preclude creation"). Also, I said Darwin's father was a Darwinist, which is also wrong. I just said it because it sounded funny. Sorry about that. What I meant is that he was aware of the notion of evolution. And many with and before him, which was my point. The reason for that was not all the fossils which were largely (though not quite exclusively!) found at a later time or the later detailed theorising. I simply meant the basic idea of evolution which is obvious when you think about it. I said something like the following before in another thread a little while ago.

Offspring are like their parents but not exactly the same That's it. That's all the info you need. The rest is thought. Well, you still need to have some notion of reality, namely that 'fitter' individuals (the ones that fit in better with their environment) will have a better chance of surviving, being fit and having offspring. But in the case of, say, deer, that is made so obvious (in the males) that the notion can't escape you. Actually, given how people these days are less in contact with nature might actually be a cause for people losing understanding of evolution. Anyway, the best adapted individuals will survive and pass on their 'good' qualities. Combine that with the variation and you get evolution. It's so obvious (indeed, once you've thought about it) that I find it hard to explain. But especially farmers will have understood. They used breeding, which is basically controlled evolution.

But to realise this you have to stop and think, which is what my remark about 'using your brain' was about. But that could easily be taken the wrong way, as you apparently did. Then again, I meant that in history many people must have stopped and thought an realised this. Which is also what I meant. Of course there are more complex issues, such as species counteradapting to each other - if cohabiting species change they change each other's environment, so the others have to adapt to that, etc. But the basic principle of evolution is extremely simple. Once you've thought about it. And many must have done so in the history of mankind. I wonder when the first such thoughts sprang to people's minds. Was it a result of breeding cattle and such (even hunting dogs?) or was that developed from an understanding of evolution?

You say that creationism is on the rise in the US because evolution is not taught well enough. Then maybe that should be done first by stripping it from its complication, like I tried to do above (not too well, though, I'm afraid). Simply ask kids the question how breeding works. Inspire them to think for themselves. Ask the right questions and they'll take it from there (well, some anyway). By the way, we're not descendants of apes (which misinformed teacher taght you that :) ). We are apes. DirkvdM 08:17, 3 November 2005 (UTC)

A little comparison to illustrate the above. The basic principle of evolution is much simpler than, say, that of gravity. That two objects attract each other is not obvious at all (and when it is obvious they do, it's for a different reason, like magnetism). So it took a long time for that notion to get thought through (still, well before Darwin, though). And even the less obvious notion that the Earth is round was already discovered by the Greeks. But for that you have to live by the sea to see its curvature and have some understanding about the qualaites of water. So, come to think of it, didn't the Greeks have a theory of evolution. Surely there must have been some ancient Greek who came up with the notion of evolution. DirkvdM 08:37, 3 November 2005 (UTC)

I disagree with that as well. The ancient Greeks were not largely evolutionists either. At that time, creationism seemed to make more sense because they hadn't been looking at a large array of species with the detailed and interested view of scientists looking for how change happens over time. In fact, evolution in general would be much harder to prove than gravity. Gravity, which is the force of attraction between two bodies that exists between all things was easy to think of when the planets were further identified and their respective orbits were seen circling larger bodies. The idea that "some ancient Greek [surely must have came up with the notion]" is giving a large amount of credit to individuals in society. There aren't a great number of free-thinkers out there who can think of one single difficult theory like that alone on an isolated Greek island. In fact, the accumulation of knowledge about evolution happened largely because of the growth of fossilized remains. Similarly, evolution requires great proof. There is debate in the scientific community as to what constitutes a species, but scientists have been able to isolate populations of a certain species and let them breed separately, and when the two were reunited, they usually chose not to mate with each other. This is still not solid proof of evolution because they are not really "species" much like there are anthropologists who debate race among humans.

To expand further on the idea that children aren't being taught evolution well enough, many evolutionists are very happy to announce that a belief in evolution increases with greater education, meaning that children need to think it out for themselves over time and often do come to the thought of evolution. However, they had to be taught this very well over a long time. Many had to rethink their faiths and their schema of the world greatly. You make it sound very simple because you probably never had to. You were taught one pattern and one idea about your origins and your life and never had to "use your brain" to really think it out. Breeding and genetic variation are very good examples, but in order to say definitively evolution does exist required a lot more evidence and solid facts than you give credit for. You continually compare yourself to a higher individual or a free-thinker much like that Greek you made up, but in fact, you must remember, you didn't discover evolution. You had the evidence and the knowledge accumulated for you and you had to use that to learn the truth. I largely doubt your sure-fire thought that evolution is "obvious". The same goes for your approach to teaching it to children. You say, tell them to see it for themselves. You can't say you saw evolution. You can't just say "believe it like I did" right away and say "it is extremely obvious". Another thing of interest is the immediate separation you make, almost like religious denominations. "well, some [will take it] anyway". That means you want some to just believe something because you say so and would separate yourself from the others, telling them to "go look and you can see evolution", practically ignoring any criticism of your ideology. That isn't science. A scientist would defend his theories. To say "some will learn it, the rest will have to go look for it" is not scientific or educational. That is dogmatic in a sense. Again, don't take what you know of in such an arrogant form. The ideas of evolution are the result of an "evolution" of theories and evidence that eventually led to more concrete knowledge. It isn't a process you can go out and demonstrate to the class. It is indeed not obvious, but more of a learned and complicated branch of knowledge. It is among the fundamentals of science, crucial to our understanding of living things, but is not very "basic". Even the basic models have experienced scientific thought--gradualism, punctuated equilibrium, and genetic variation--all added and combined to make the theory bigger and better, so it wasn't an unmoving and stable idea that you can "see for yourself". Don't confuse science with dogma and don't think the education system is doing such an adequate job if we can see great confusion among school districts across the country.--Screwball23 ^talk 17:17, 3 November 2005 (UTC)

While the Theory of Evolution, and science in general, don't eliminate the possibility of creationism, say in the form that "God created the big bang", they do eliminate the version of creationism listed in the Bible, Torah, Koran, etc.

In short, when creationism is sufficiently vague, it can't be tested and refuted. However, when it is specific enough to be verified, it can be disproven. For example, accounts of the creation of the Earth being several thousand years ago can be disproven in many, many ways. Those include radioactive decay, continental drift, magnetic reversals, biodiversity levels, etc. StuRat 17:04, 1 November 2005 (UTC)

I'm sorry, I used the wrong term, I meant 'creation'. 'Creationism' is much more specific. Btw, all your arguments can be wiped off the table with the argument that God created those illusions to test our faith :) . That is, all but the first. DirkvdM 09:37, 2 November 2005 (UTC)

That is very true. A belief that evolution was put there to "tempt mankind" into secular humanism would ruin the relationship between science and religion entirely. That would make all we know of through evolutionary science a type of pseudo-science because of a greater master plan. Unfortunately, this view is directly connected to religion and would encompass presumptions for which there are no experiments. That would only disprove macroevolution (the evolution of different higher species) but wouldn't stop microevolution, which can be proven very well now. That would be a very slippery ideology and would accomplish all that creationists are angry about--the descent of man from ape-like ancestors. Such a view is assuming a different nature to the Divine One and is a simple dismissal of all that evolutionary science and anthropology has taught us. It's an interesting idea.--Screwball23 ^talk 19:23, 2 November 2005 (UTC)

• After the reception of Origin of Species, a handful of "heirs" came out of the woodwork to claim priority. There is little evidence that Darwin took anything substantial from them -- his main influences, both in the genesis, formation, and articulation of his theory, came from sources which he cited excessively. I don't know the details of the Blyth question in particular, but the fact that the main link given to support the line in the article is from an anti-Darwinian Creationist article, I removed it as being fairly POV. If it is something of relevant historical consequence it should not be hard to find a legitimate source. In any event, it would be worth noting that Darwin's theory was one about speciation -- the emergence and differentiation of species of animals, not just that sick animals die off more than healthy ones. --Fastfission 03:28, 3 November 2005 (UTC)

BIODIESAL FUEL MANUFACTURING

I have a high interest in both the environmental and financial benefits of converting used cooking oils into biodeisal. Problem is that I have no idea of where to begin in researching relative equipment, necessary chemicals for the procedure, and overall cost of initial set up. Also to consider is the different environmental laws to be met dependant upon the different states. Help!!! Chris --**--

I believe an experiment was done where two people drove cross-country using a conventional engine with only minor modifications and using cooking oil from restaurants as fuel. The only processing they performed was to filter the cooking oil. StuRat 20:13, 31 October 2005 (UTC)

That is known as using Straight Vegetable Oil. It's really not a good idea in an engine you value because in using SVO varnishes form that coat the engine. Biodiesel, which is processed vegetable or other oils, is expected to be free from those problems. To the original asker, our biodiesel article gives the overview, but if you check through the links at the bottom, you'll find much of the best information available online for what is needed to make biodiesel. Particularly good websites include http://www.biodieselcommunity.org/ http://www.journeytoforever.org/biodiesel.html and the forums at http://www.biodieselnow.com/ for questions. Also read our articles Biodiesel production and Biodiesel recipe for more detailed overview of making the stuff. Some of those links include detailed tutorials on how to make your own homebrew. This article is one of the article's references, and contains a lot of detailed information on the numbers behind setting up a biodiesel production plant. - Taxman ^Talk 23:15, 31 October 2005 (UTC)

The articles on biodiesel give a good starting point, and, depending where you live, there are probably associations not too far from you that do this. Where do you live? Trollderella 22:44, 31 October 2005 (UTC)

Given that he refers to state laws but doesn't mention the country, my guess is the USA. DirkvdM 10:38, 1 November 2005 (UTC)

Yes; that is correct. I am in the states, but more exact, I'm Military (Air Force) at Andrews AFB. So a concern on environmental laws would cover Maryland, Virginia, Delaware ... Been in 20+ years, so who knows where/what governing EPA laws I'll have to be concerned about next. Gotta say though, initially saw an overveiw of how Biodiesal is made on Dish Network "Dirtiest Jobs". Never dreamed there was a website like this, and I want to Thank You All very much for the information. MSgt Christopher Dow

The Australian rat, the most sexually active animal

Im doing a research on the most sexually active animals on the face of the earth. It has come to my attention that a certain wild rat in Australia is the MOST sexually active as during the mating season, the male rat goes on a mating rampage where it does not stop to eat or drink but goes on mating for weeks until it dies of hunger and dehydration. may i know the nam of this particular rat? thank you very much.

Mel Gibson ? StuRat 22:56, 31 October 2005 (UTC)

There is show on TV in Australia tonight, Sex in the Bush, that deals with this (on the ABC). Its promo includes the text "Male marsupial mice literally copulate themselves to death". I don't know if this is a coicidence (ie: you have seen this promo), but I'll watch the show anyway and try to get the exact name of this mouse. --Commander Keane 08:51, 1 November 2005 (UTC)

LOL, nice one StuRat. :-) Akamad 10:54, 1 November 2005 (UTC)

The mouse was on Wikipedia all along: Antechinus. Indeed, the article mentions its "sex-crazed rampage". It was mentioned on that show I watched.--Commander Keane 12:41, 1 November 2005 (UTC)

"The mouse was on Wikipedia all along"? was that the symptom of it being sex-starved or the causation? Johntex\^talk 19:41, 3 November 2005 (UTC)

I think that's a question we all ask ourselves at some point... User:Omegatron/sig 20:19, 3 November 2005 (UTC)

November 1

sea water what is the boiling poing?

I once did the calculation for water with salt added to find out if that would make potatoes cook faster, and the result was something barely over 100 C (just a tenth of a degree or something). I assume sea water won't be much different, so my guess is something like 100.1 C.

what colour is water

I've had many a debate about this and have read different explainations. So i thought I'd see what you guys thought. What colour is water ??? The dictionary describes it as a colourless, odourless liquid. if this is true why are oceans green and blue. This has been explained away by saying that blue oceans typically contain zooplankton and green oceans contain more degrees of photoplankton. -- freddy

I agree. Pure water is colorless. The blue color in lake water and blue-green color in seawater are due to impurities. StuRat 00:25, 1 November 2005 (UTC)

• Pure water is slightly blue, because there's an (weak) overtone of the O-H stretch absorption resonance in the red. (Pure heavy water - deuterium oxide - is colourless because the O-D stretch is at a longer wavelength). Scattering almost certainly plays a part, too. But these are very weak effects and most of the colour in the oceans is due to sealife. --Bob Mellish 00:33, 1 November 2005 (UTC)

  Indeed so. For more details, see [7]. —Ilmari Karonen (talk) 00:45, 1 November 2005 (UTC)

  Also, note that much of the blue color seen on the surface of the sea is simply reflected from the sky (which is blue due to scattering). On an overcast day, the sea generally looks rather gray too. —Ilmari Karonen (talk) 00:50, 1 November 2005 (UTC)

I'm glad somebody mentioned the sky. One might say air is clear, but with enough of it, and at a distance, it is clearly blue. I'm speaking of the air we breath ofcourse, and the blue sky we see as a result of it. The same analogy can be used to deduce the color of water. A handful of water may appear to be clear, but with enough of it, even free of any impurities, it may in fact take on a blue hue. I would have to agree with Bob Mellish. - Cobra Ky (talk, contribs) 03:21, 1 November 2005 (UTC)

Note that the sky isn't actually necessarily blue. See our article on Rayleigh scattering for an explanation of why the sky usually appears blue, but why thicker slabs of air (as seen at sunset, for example) can appear other colours. (See also green flash for a really neat atmospheric phenomenon.) Lastly, check out Mie theory for an examination of how suspended particulate matter (volcanic dust, industrial pollution) can also colour the sky. (Oops—I shouldn't forget diffuse sky radiation, too.) The apparent blue colour of the sky isn't due solely to intrinsic 'colour' of the air, but a combination of scattering effects, the nature of the source of illumination (the Sun), and the sensitivity of the photoreceptors in our eyes. TenOfAllTrades(talk) 03:51, 1 November 2005 (UTC)

Wind Strength

What methods do meteorologists use to measure wind strength?

They use an anemometer? --cesarb 02:26, 1 November 2005 (UTC)

And here I thought that device was used to measure the number of sea anemones in an area. StuRat 02:36, 1 November 2005 (UTC)

An anemometer measures wind speed, so a wind's strength is just its peak gust speed.--Commander Keane 05:43, 1 November 2005 (UTC)

Flash Drive

Would i be able to download a DVD players and save it to a Flash drive and then save it to another computer?

You certainly can, there are many legally availbale DVD players online, a bunch of them a listed here. Download the installation file and copy it to which ever computer you wish to install it on. Akamad 02:25, 1 November 2005 (UTC)

Runge-Kutta Method

I understand how to use Runge-Kutta methods to solve a first order differential equation, but I'm not sure how to adapt it to a second order equation like the harmonic oscillator. I'd assume you'd break the second order equation into two first order equations, (and I have solved this problem using Euler's method) but I don't know how to adapt the more accurate RK procedure to two coupled equations.

Anyone know of any good references either in print or online to help me learn it? Thanks. Vonspringer 04:08, 1 November 2005 (UTC)

I know I was supposed to learn this last semester, but I'd have to go grab my textbook to give you the details. I believe if you're only interested in a numerical (as opposed to analytic) solution, the trick is to turn the second-order equation into a system of first-order equations. So if you have y''=2*y, you can turn this into the system {u=y'; u'=2*y}. Does that make sense? I'll try to remember to bring Heath's text in tomorrow. —HorsePunchKid→龜 07:44, 1 November 2005 (UTC)

"Local Mode" showing on my Nokia phone

Hi,

I have a cheap Nokia phone (don't know the model) which has suddenly frozen with the words "Local Mode" showing. It can't be turned on or off. Some internet searching shows that this is something to do with testing and/or transfering files, or something, but I can't find out how to unfreeze the phone. Any thoughts? Thanks!

If you're using a data cable (e.g. a USB cable that plugs into the phone), follow this advice: "In my experience for many 8310/6510's just disconecting and reconnecting the data cable is not always sufficient as the words "Local mode" remain displayed. If this is the case simply remove the USB power cable for a second and plug it back in." If you are not using a data cable, then I believe that the phone's flash has been corrupted, take it into any phone shop and they should be able to flash it for you. If you want to know the model of the phone, take out the battery, it'll be written on the white sticker underneath. Good luck! --08:29, 1 November 2005 (UTC)

RED HAT ENTERPRISE LINUX

WHAT IS RED HAT ENTERPRISE AND WHY IS IT AN OPTION

WHAT IS RED HAT ENTERPRISE LINUX?

Red Hat Linux is a particular distribution of the GNU/Linux operating system. It is a relatively popular choice for server administrators who want a cheap, unix-like operating system but who still want paid tech support as an option. —HorsePunchKid→龜 07:38, 1 November 2005 (UTC)

Planetary sling shot

Space craft that go beyond Mars are quite often accelerated using a sling shot effect, by passing close by some heavenly body. Of course they will get accelerated when they approach it, but after that they have to escape the gravitational pull to continue, which would annihilate the effect. So how does this work? I imagine it has something to do with either the change in direction or approaching the planet (or whatever) 'from behind' (relative to its motion), thus not using the gravitational pull but the speed of the planet. DirkvdM 10:47, 1 November 2005 (UTC)

amakuru mu kirundi

I've been to Burundi, but the only local language I made an attempt at was Kiswahili, so what does this mean? DirkvdM 09:10, 2 November 2005 (UTC)

There are three types of orbital motion, parabolic, (ballistic trajectory) elliptical, and hyperbolic. By approaching a planet in a hyberbolic orbit, we don't accelerate from the gravity of the planet, but we acquire the velocity or twice the velocity of the planet's motion. If the planet was stationary, all we would do is change direction. Since the planet is moving, we acquire the velocity of the planet while accelerating around it in the hyperbolic orbit. A good explanation is here. [8]Dominick ^(ŤαĿĶ) 12:48, 1 November 2005 (UTC)

The key is that the spacecraft steals some angular momentum from the planet. Since the planet is so much bigger than the spacecraft, the planet's speed changes negligibly, but the spacecraft gets a big boost. If the planet were stationary than the trick would only change the spacecraft's direction. — Laura Scudder | Talk 16:37, 1 November 2005 (UTC)

• This requires a bit longer answer.

The trick to thinking of this situation easily is to use frames of reference. Imagine you are standing on a road, looking south, and a car comes toward you at a speed of 50 (mph or km/h, whatever units they use where you live). You throw a ball directly toward the front of the car, at a speed of 40, and step out of the way. They are closing at a relative speed of 90... that is, in the car's frame of reference, the ball is moving south at a speed of 90. We assume that the car and the ball are perfectly elastic bodies, that is, the ball does not waste energy in denting the car or anything like that. Then the ball will bounce back from the car at a speed of 90 in the opposite direction, north. But that's 90 relative to the car... so in your frame of reference it's now going at 140! Don't try this at home!

Now consider the same situation, only this time you turn away from the car and throw the ball north at a speed of 20 (before stepping aside), so that the car catches up with it. The car is moving north at 50, so in the car's frame of reference the ball is moving south at 30. Hitting the car, it bounces north at 30 in the car's frame of reference... which is 80 in yours. Same idea as the first experiment, although the speed change is less dramatic in this case.

In both cases, if you measure closely you will find that the car has slowed a little, as the ball stole some of its momentum. This shows up as a change in the speeds of the two frames of reference relative to each other. But for purposes of understanding the experiment, this can be pretty much ignored.

The car example is one-dimensional. For planets and spacecraft, you have to think in at least two dimensions. Here is how it looks in the planet's frame of reference: The spacecraft approaches from a distance and falls toward the planet on an off-center path. The planet's gravity causes it to follow a hyperbolic orbit. The symmetry of this shape means that the spacecraft departs at the same speed as it was approaching originally, but in a different direction. The effect is very much as if the spacecraft had simply bounced off the planet, even though it is being pulled by the planet's gravity, and not pushed by the (electromagnetic) forces involved in bouncing a ball.

Okay now, in your frame of reference, the planet is moving along its orbit. For simplicity, say it comes up almost directly behind she spacecraft, like the second car/ball example. Then in your frame of reference, the spacecraft may end up moving in very much the same direction as before, but considerably faster. The details of the before and after directions are actually more complicated and not the sort of thing you can do in your head; for one thing, it depends on how close the spacecraft comes to the planet. But this gives the general idea.

(Typically the planet and spacecraft will be moving in the same direction, like the second car example; this is because the Earth's own orbit, which is also in the same direction, determines which orbits can be reached at reasonable cost.)

You asked if it is "not using the gravitational pull but the speed of the planet". You should now see that it is using the gravitational pull in order to use the speed of the planet. It has stolen a tiny bit of momentum from the planet (and, in the same interaction, some of its angular momentum as well).

--Anonymous, 00:17 UTC, November 2, 2005

So, if I get it right, what it comes down to is that the spacecraft steals some of the momentum of the planet (which, for all practical purposes has an infintitely larger mass). Dominick's link was quite helpful (if a bit too mathematical - I prefer understanding things on a more 'philosophical' level). Thanks. DirkvdM 09:10, 2 November 2005 (UTC)

Psychoactive Drugs

I was wondering if any societies, past or present take psychoactive drugs to control any unwanted behaviors?--207.119.216.109

Societies don't take drugs. People do. If you are asking if there are any societies in which individuals are encouraged to take psychoactive drugs to control unwanted behavior, the answer is of course: ours. Nearly all psychoactive drugs except antidpressants are prescribed for unwanted behavior. alteripse 16:00, 1 November 2005 (UTC)

Ritalin is a good example. I suspect you meant to ask about psychoactive drugs which are illegal in the West, such as cocaine. Is that correct ? StuRat 16:50, 1 November 2005 (UTC)

Of course there is also a third category, non-prescribed (ie recreational) drugs that are legal in the West today, but those are pretty much a rarity, alcohol, nicotine and cafeine being exceptions. In modern pressure cooker society laziness is rather unwanted behaviour and cafeine helps remedy that. DirkvdM 09:18, 2 November 2005 (UTC)

Ritalin is the best example of a drug imposed on children through society. These days, many American children are expected to be protiges and big-time pros at skills through the guidance of their parents. This stress and immediate stress on schoolchildren has manifested itself in a new industry in the United States--the Leap ahead movement involving Leapfrog, tutors, college coaches, the Kaplan/Princeton Review courses, and an enormous amount of marketing to college-savvy parents who want their children to all grow up as great experts and masters of the world. Ritilin is pressured on many children who do not have ADD because school administrators--especially those in small schools--pressure parents to advance their children with psychoactive drugs. The millions of American schoolchildren wouldn't be on ritalin if American society didn't place such immediate demands on children to behave in the rigid institutionalized school system. If you are interested in fictional dystopias with drug use, the Giver and Brave New World were excellent books describing what drug-altered societies would look like.--Screwball23 ^talk 19:40, 2 November 2005 (UTC)

Chemistry

What happens when an alcohol burns? If the reaction is exothermic or endothermic or not.Please also explain the bond in the alcohol, how it is broken and how products are formed.

• Do your own homework, start by looking at exothermic and endothermic and at the pages that are linked. You might want to look at alcohol as well. Physchim62 (talk·RfA) 18:50, 1 November 2005 (UTC)

Dont forget combustion Theresa Knott (a tenth stroke) 23:40, 1 November 2005 (UTC)

Technical Terms

I have a BA in English. I work as a technical writer. I've been using your site as a tech. dictionary with a good deal of success! and appreciate all that you offer. But, today I came across the need to read a definition of:

Tab delimited Pipe delimited

and neither were located on your site. Can you recommend where else I can obtain a definition?

Who is your closest competition for offering explanation of technical issues/concepts/terms?

Thanks, Peggy McLean, VA

• Both refer to file or data formats. "Tab delimited" means items are separated by tab characters (ASCII code 9). So the file might look like "10<tab>20<tab>5.5<tab>100" etc., to represent the numbers 10, 20, 5.5, 100 in that order. "Pipe delimited" means the same thing but separated with the pipe "|" character (ASCII code 124). So the same file would be "10|20|5.5|100". Tab delimited files are common for spreadsheets and the like. I don't know what type of program would use pipe delimited. --Bob Mellish 19:02, 1 November 2005 (UTC)

Pipe delimited text is common for many data formats (HL7 for one). It is simply a matter of choosing a character that will likely not be used in the data itself. The choice of commas and tabs always struck me as rather dumb since both are common in user-data. Kainaw 19:10, 1 November 2005 (UTC)

There is a Wikipedia article on this at Delimited. I will add redirects so that this can be found using the search terms you used. -- Canley 01:56, 2 November 2005 (UTC)

The Archives of the Internet

I would like to see the history of the internet. If I could see a group of websites and look at their archives, I could learn quite a few things of interest. I would like to see how certain websites changed, or how many ads there were on the most popular webpages back in the 80s and how campaign webpages change as an election progresses, and maybe even see dead websites, or ones that are not updated often. Is there a place where I can see the archives of the internet? I looked at archives.org and I was disappointed. I wasn't able to search very easily at that site. Are there any others? Where can I view these archived websites?--Screwball23 21:21, 1 November 2005 (UTC)

Why don't you log in as a user? This isn't a requirement but you seem to be expending some effort to appear logged in. --hydnjo talk 21:57, 1 November 2005 (UTC)

OK then. It seems that you are logged in and just not sig linked. Sorry, I was confused. --hydnjo talk 00:36, 2 November 2005 (UTC)

Archive.org isn't intended to show you "the internet of a certain date", but rather what a specific site looked like on a certain date. It is, however, the only major archive service I know of for the web - there are no single "archives of the internet", because the internet is not a centralised collection of information.

Note also that there were no webpages in the 80s; you could try reading the Usenet archives at groups.google.com, perhalps... Shimgray | talk | 22:10, 1 November 2005 (UTC)

• Try the Way Back Machine it will show you what websites looked like at various points in time. Good luck! Johntex\^talk 22:44, 1 November 2005 (UTC)

• You won't find any records of web sites from the 1980s anywhere; the Internet was around then, but the Web is only part of it, and wasn't started until 1990. See those two links and also History of the Internet. --Anonymous, 22:20 UTC, November 1, 2005

I always thought of the internet and computers in the late '80s. You're right. The World Wide Web wasn't in the '80s. That was interesting to know.--Screwball23 ^talk 03:18, 2 November 2005 (UTC)

The most popular websites now

What are the most popular websites people visit in the US? Is it much different across the world? What about the number of google searches people do everyday? Is there a list of the most popular google searches? How has that changed with time?--Screwball23 21:25, 1 November 2005 (UTC)

Why don't you log in as a user? This isn't a requirement but you seem to be expending some effort to appear logged in. --hydnjo talk 21:59, 1 November 2005 (UTC)

Actually, he was logged in. He just hasn't made his name clickable. --Pidgeot (t) (c) (e) 23:57, 1 November 2005 (UTC)

Ah, Ok thanks. --hydnjo talk 00:31, 2 November 2005 (UTC)

• Try Alexa Internet. Good luck! Johntex\^talk 22:48, 1 November 2005 (UTC)

November 2

pharmacokinetics?

I am wondering what the impact of renal failure, genetics or ethnicity and hypoalbuminemia is on absorption, distribution, metabolism and excretion of drugs?--24.235.133.63 00:18, 2 November 2005 (UTC)

1. Renal failure slows the excretion of those drugs that are eliminated from the body by urinary excretion rather than metabolism. It has less effect on absorption, distribution and metabolism (with certain exceptions for each category).
2. Genetics accounts for small differences in rates of metabolism for many drugs, large differences for a few. Few genetic differences are of major clinical significance. Genetic differences of absorption, distribution, and excretion are less important, assuming major organ systems are properly working.
3. Ethnicity is a subset of genetic differences. All items are as described above for genetics.
4. Hypoalbuminemia affects those drugs that bind to albumin. It can accelerate metabolism, restrict apparent distribution volume, and accelerate renal excretion.

Now, don't you feel a little embarrassed queuing up with the seventh graders to have your homework done? I hope you aren't taking care of patients any time soon. alteripse 02:00, 2 November 2005 (UTC)

And on behalf of the world's *patients* I sincerely hope you (the anonymous med student, not Alteripse) aren't looking after us any time soon. Sheesh. Haven't you heard of the damn textbook? --Robert Merkel 02:56, 2 November 2005 (UTC)

solubility

how can differences in solubility be used to separate a mixture of solids?

how can differences in solubility be used to solve homework questions? --R.Koot 02:36, 2 November 2005 (UTC)

• Try reading solubility and precipitation (chemistry). If you can get one substance to dissolve while the other one doesn't, you can filter off the nonsoluble substance and separate the mixture. - Mgm|^(talk) 21:19, 2 November 2005 (UTC)

Applying imaginary numbers type -- Mathematics

What occupations require the use of imaginary numbers referred to as "i" (i^0, i^1, i^2, i^3, etc)?

Electrical engineering do, to analyze circuits. They're also important in signal processing. There are other fields, probably, too. Dysprosia 02:48, 2 November 2005 (UTC)

Like math teaching? alteripse 03:08, 2 November 2005 (UTC)

Of course! But that's probably not what the question-asker had in mind, I think ;) Dysprosia 04:40, 2 November 2005 (UTC)

Researcher in physics, computer science (quaternions are of some use in computer graphics). --R.Koot 03:18, 2 November 2005 (UTC)

Quantum mechanics. Really, all of physics. e^ix is a convenient shorthand for sines and cosines if nothing else -- SCZenz 03:24, 2 November 2005 (UTC)

Economics! In fact, the famous Mandelbrot set was the result of Benoit Mandelbrot's studies into the fluctuations of the price of cotton over the centuries. --jpgordon∇∆∇∆ 03:31, 2 November 2005 (UTC)

Engineering, of course. Or really anything that applies analysis. — Sverdrup 23:36, 2 November 2005 (UTC)

Chemistry - PAN

A PAN is a polyatomic negative ion or a polyatomic nonmetal group. What does this mean (in English please)? Also, what are the 7 Home Base PANs?

Polyatomic negative ion, or a radical, is a molecule made of several atoms that does not have its electic charges balanced. An example is hydroxide (OH), with a charge of -1. The other ones, I'm not sure, I'm not a chemist). Titoxd^(?!?) 03:27, 2 November 2005 (UTC)

I haven't heard that term before, but there are a number of polyatomic negative ions important in biology: PO4, SO4, HCO3, NO3. Here is a link that gives many more: [9] alteripse 04:15, 2 November 2005 (UTC)

I haven't heard the term either: PAN in chemistry usually refers to polyacrylonitrile. The above ions should be PO₄^3-, SO₄^2-, HCO₃^- and NO₃^-: many more examples can be found in Category:Anions. All the atoms in the above anions are nonmetals. Physchim62 (talk·RfA) 06:21, 2 November 2005 (UTC)

Parasite

What is the name of the parasite that turns ants into zombies thay get ate by rabbits that releases it's eggs in rabbit feces that snails eat that cough up a snot/parasite ball that is ate by an ant which is turned into a zombie that get ate by rabbits that....

The concept of this ant is an intellectual spore disseminated by the Museum of Jurassic Technology [10]. It gradually expands to take up more and more of your waking thoughts. At a certain point it will induce you to root around in the dirt until you unearth a computer cable, at which point you will clamp your jaws permanently around it with no desire to eat or drink ever again. As your desiccated body disintegrates the spores of the idea penetrate the cable and are disseminated to other unsuspecting victims. alteripse 10:32, 2 November 2005 (UTC)

• I think Trematoda is what you are lookign for. 10:36, 2 November 2005 (UTC)

Could it be the Lancet Fluke dicrocoelium dendriticum [11] zombification of the ant? Dominick ^(ŤαĿĶ) 15:18, 2 November 2005 (UTC)

Looks like a near-perfect match to me. I suspect the resemblance between this story and the MJT version above is no coincidence. alteripse 16:03, 2 November 2005 (UTC)

Temperature variation of air.

Why is flowing air always cooler than static air? Is it an apparent phenomenon or is it due to the change in energy of the air molecules? --StratOnLSD 11:48, 2 November 2005 (UTC)

Moving air is capable of allowing for evaporation from the skin more easily than still air, thus cooling the skin. This is because of two reasons: firstly the air is continually replenished and replaced by drier air, and secondly moving air has lower pressure, thanks to Bernoulli's principle (See vapour pressure). -- Ec5618 12:01, 2 November 2005 (UTC)

Flowing air is cooler only to your skin, not to a thermometer. Flowing air removes the air you have warmed and replaces it with cooler air. It can also accelerate perspiration or moisture loss in some circumstances, which is also cooling. alteripse 11:58, 2 November 2005 (UTC)

An interesting note is that at high temperature and high humidity, wind (moving air) will actually feel warmer than still air. This is because as humidity rises, your body can no longer use evaporation as a means of cooling, and moving air then feels more like a heater than an air-conditioner. --Quasipalm 14:17, 2 November 2005 (UTC)

On hot days in Perth (eg above 40°C = 104°F), even though the humidity can be as low as 20%, the wind is hot on the skin. It's not to do with humidity in that case.--Commander Keane 06:16, 3 November 2005 (UTC)

The reason for which would be that this is air that is hotter than the body temperature. If the air stands still a layer of air is formed around the body that is closer to the body temperature. So when the air moves that layer is replaced with the hotter air. Conversely, if the temperature of the air is below body temperature that will help the body to release its heat, thus cooling it down. By the way, an airconditioner works by cooling the air down. A better comparison would be a fan, which also works by moving air past your body. DirkvdM 10:06, 3 November 2005 (UTC)

Titration/Volumetric Analyisis

Hi, could you please tell me what titration or volumetric analysis is used for in industry and in every-day life?(could you please keep the answer to a gcse chemistry level please) Thanks for the help, fv--217.22.182.30 14:56, 2 November 2005 (UTC)

You really should do your own homework. Take a look at titration and run a google search for volumetric analysis.--Screwball23 ^talk 19:27, 2 November 2005 (UTC)

November 3

Construction of Hale Telescope at Palomar Observatory

In November, 1947, the 200" mirror was transported by flat-bed truck(s) to Palomar Mountain. What was transpoted to the future observatory site, in a similar manner, in 1943 or 1944 or, maybe 1945? I lived in Oceanside, CA at the time and remember somethig (my memory tells me it was the mirror, but now I know it wasn't)reqiring the overhead electrical wires on Hill Street and Mission Avenue to be raised, or temporarily removed, to allow passage of the--what? My guess, now, is that it must have been the tubular housing for the telescope. Do you know what it was? I would like very much to know.

I don't have a ready answer, but the details of the construction are recounted in a highly acclaimed history of the project, The Perfect Machine: Building the Palomar Telescope by Ronald Florence. ISBN 0060926708

--Tabor 00:28, 3 November 2005 (UTC)

Poking around on the Caltech site, I found this image; it's described as "[a] huge disk of concrete and steel [that] was used [to] balance the telescope in the 1940's before the mirror was finished". It's likely that this would have been built offsite and brought in - and if it was used as a balance for the telescope, then it probably is about the same size and weight as the mirror. This page suggests that the telescope tube was on site in about 1937-8. Shimgray | talk | 01:13, 3 November 2005 (UTC)

long division symbol

My college professor swears that there is another name for the long division symbol. I have been frantically searching the internet for the answer. Every site says that there is no specific name but is a vinculum. Is there another name for the long division symbol that you know of? Help!

If he knows of one, the best way to find it out is to ask him. Mention that you've found sites, like this that say it has no name other than "long division symbol". - Nunh-huh 00:32, 3 November 2005 (UTC)

There are a number of variations on the symbols for division, but I'm thinking that the original poster is talking about the one that looks like a right parenthesis ")" with a line extending rightward from its top... right? The horizontal line might indeed be called a vinculum, but normally that word refers to a similar line with other meanings. But as to the parenthesis... in Florian Cajori's A History of Mathematical Notations it is called a lunar sign. Sometimes in short division the quotient is placed to the right and set off by a left parenthesis, like this: 16)512(32. Cajori calls this parenthesis a lunar sign as well. --Anonymous, 05:12 UTC, November 3, 2005

Mars

Where is Mars located? Name:Aidan McCarthy Age:8

Hi, Aidan!

Mars is currently about forty-five million miles from Earth, on the side of us away from the sun. Here's a diagram showing the solar system from "above"; Mars is the red dot in the upper right corner, whilst we're the blue one just beside it.

For astronomical information on where Mars is, go here and enter your location; it'll be able to produce a sky chart showing you where Mars can be seen, right now, from where you are. (Over most of the USA, it's currently in the sky to the east) Shimgray | talk | 01:21, 3 November 2005 (UTC)

Where Mars can be seen in the sky depends on the time of day because the Earth rotates around its axis, and thus the stars and planets seem to move along the sky just as the Sun seemingly moves along the sky during the day. Actiually, Mars can also be overhead during the day, but you just don't see it because the Sun is so much brighter. The same goes for the stars - they're always there, but you can't see them during the day. So over one specific night Mars seemingly moves in unison with the stars. But if you check over different nights, you'll see it moves relative to the stars. The reason for that is that the Earth and Mars also revolve around the Sun (the lines in Shimgray's first link are the orbits they follow). But they do this at different speeds. So at one moment they may be at the same side of the Sun, which is when you'll be able to see Mars in the night sky. And because Mars is in an orbit further from the Sun than Earth, it will be roughly on the opposite side of the Sun, as seen from the Earth. It is said to be in opposition then. The table at Mars#Appearance, second column, shows that in four days, Mars will be in opposition, which is the best moment to see it. It is then (and roughly now already) on the opposite side from where we see the Sun (hence the name 'opposition'), so when the Sun sets in the West, Mars rises in the East. Around midnight it will be roughly overhead (just as the Sun is at midday) and at daybreak it will set in the West, when the Sun rises in the East. About one year from now, it will be on the other side of the Sun (the last column), and then you can't see it. 'Conjunction' means that it is in roughly the same place in the sky as the Sun. So then, at midday, it will be right up there overhead, next to or even behind the Sun. It'll be there. You just can't see it. DirkvdM 10:44, 3 November 2005 (UTC)

'Dirty Dozen' - Forensic Entomologists

Ok, so I've got Greenberg, Neal Haskell, Meek, Lee Goff, Paul Catts, Hall, Lord, Ralph Williams, and Ted Adkins. Can someone give me the names I'm missing? (Not just the last three entomologists, but first names for the ones I have.) Pretty please? DuctapeDaredevil 03:49, 3 November 2005 (UTC)

Brain damage

How come the brain can't repair itself? It doesn't make sense that nerves cells can't reproduce.

One reason I can think of is that brain cells differ from other cells in that they're not functional as 'newborns'. They derive their function from their specific connections with other nervecells. You can just produce red blood cells and inject them inot the bloodstream and they'll do their job. I can imagine that if a new muscle cell is made, it will just attach itself in a standard way. But a brain cell doesn't attach in a standard way and then function. It derives it's function from how it is attached. So it can't just be replaced. A new brain cell could only take the place of a dead one if it were to go through the exact same learning experience, which will of course never happen. So the specific memory aspect can't be restored, but that's still no reason for nerve cells no to reproduce. So I haven't really answered your question. Sorry. One answer might be that the brain starts out with an overwhelming overkill of cells to eliminate the need. The neuron article oddly doesn't seem to address this. But I believe that it has recently been found that neurons do repoduce. Anyone now? DirkvdM 10:57, 3 November 2005 (UTC)

I think the previous answer is on the right track. That is, nerve cells can reproduce, but can't really replace the dead ones, since the connections the cells had are now lost. This is why stroke victims and others with brain damage must frequently relearn language and other skills, as new cells learn the old pathways again. Why haven't we evolved a better backup system for brain damage ? Well, any duplicate system would be quite complicated, such as a redundant brain somewhere with all duplicate pathways, and would likely cause more problems than it would solve. We do have a few redundant organs, like kidneys, lungs, eyes, and ears; but most of our other organs are similarly singular. Those which do serve a redundant purpose also serve an addition function. That is, your body does better using both kidneys, lungs, eyes, or ears than with only one. StuRat 15:06, 3 November 2005 (UTC)

The nervous system is a huge network. The skeleton, for example, is a large network of cartilage and calcium phosphate (among other substances). If a connection is lost as in a broken bone, a cast could straighten or "teach" the networks the proper directions, but it couldn't replace a large quantity of the bone. Similarly, the brain does demonstrate great plasticity in that it can teach certain regions of the brain information usually restricted to another if that other region is damaged. The networks can sprout alternatively from neurons, so new axons do form. However, much of our nervous systems are developed when we are very young babies so the myelination and proper networking is usually considered complete at a young age. As we become older, our brains lose their ability to branch out and create many new neurons. The specialization of our cells leads to a very fixed number of neurons and networks, so the branching and connections between neurons will be very flexible but our ability to regenerate many new neurons is not.--Screwball23 ^talk 16:34, 3 November 2005 (UTC)

Bacterial Antigens

Can anyone provide a high-level list of the different types of bacterial antigens?

• The Antigen article lists 3 types of antigens:

1. Immunogen - Any substance that provokes the immune response when introduced into the body. An immunogen is always a macromolecule (protein, polysaccharide). Its ability to provoke the immune response depends on its foreignness to the host, molecular size, chemical composition and heterogeneity (e.g. different amino acids in a protein).
2. Tolerogen - An antigen that invokes a specific immune non-responsiveness due to its molecular form. If its molecular form is changed, a tolerogen can become an immunogen.
3. Allergen - An allergen is a substance that causes the allergic reaction. It can be ingested, inhaled, injected or comes into contact with skin.

However, these could be from any source, not just from bacteria, so I'm not sure that is what you are looking for.

Bacteria have proteins, Polysaccharide, and other molecules in their cell walls which can antigens. If a bacteria is ruptured, so that proteins from the interior are releases into the bloodstream, then any of these internal proteins could also become antigens. (An antigen is basically anything that evokes an immune response). There are many types of proteins, but I am not aware of a classification scheme specific to their role as antigens. One could create a high level list by including every macromolecule that is found in bacteria: cell wall proteins, cell wall polysacharides, enzymes, etc., but this list would be a somewhat subjective as to what is included. Johntex\^talk 19:22, 3 November 2005 (UTC)

Southern Summer Solstice

Hello, I am trying to find the angle of the sun in Cairns at sunrise and sunset during the southern summer solstice.

Thank you, Gavin Silverthorne --203.51.205.128 11:32, 3 November 2005 (UTC)

There's a Sun Angle calculator here which might help, in conjunction with these sunset and sunrise times from the Bureau of Meteorology:

CAIRNS   Lat=-16°55'00"  Long=+145°46'00"
TIMES OF SUNRISE AND SUNSET 
(for ideal horizon & meteorological conditions)
Time zone: +10.00 hours
21/12/2005  Rise 0541  Set 1849

--Canley 23:53, 3 November 2005 (UTC)

Corn cob

What is the scientific reason behind the fact that the number of columns of seeds in a corn cob is always even ?

Many plants exhibit regular patterns in the growth of their leaves, seeds, and buds. The sunflower, for example always grows new seeds at the end of a spiral growing outward. Stems branch out in regular patterns as well in certain plants. The seeds on a corn cob would probably be the result of a regular phyllotaxis of the seeds. That would show why they grow in their regular patterns but the even numbers is more mathematical. The phyllotaxis of many plants does follow regular mathematical precision, which has been graphed and mapped by many scientists, but I'm not sure on the specific reason. Check and see.--Screwball23 ^talk 16:17, 3 November 2005 (UTC)

Electro Ceramics

Does porosity have any advantages on ferroelectricity & pyroelectricity & piezoelectricity? and what are those advantages? That would be very kind of you to answer me, with the best regards, F.KashaniNia

A name of a reaction

What is the reaction called that happens when an acid is turned to an alkali using sodium hydroxide?

Lucas 12

• Hi Lucas, welcome to Wikipedia. Please read Neutralization. You may also want to see Acid and Base and Sodium Hydroxide. Best, Johntex\^talk 19:05, 3 November 2005 (UTC)

Zinc

Is Zinc difficult to extract from its ore?

Lucas 12

• According to our article on Zinc: "Zinc metal is produced using extractive metallurgy. Zinc sulfide (sphalerite) minerals are concentrated using the froth flotation method and then usually roasted using pyrometallurgy to oxidise the zinc sulfide to zinc oxide. The zinc oxide is leached in sulfuric acid and the resulting solution is purified using zinc dust. The metal is then extracted by electrowinning as cathodic deposits. Zinc cathodes can be directly cast or alloyed with aluminum. Another process to produce zinc is flash smelting, a pyrometallurgical process. Then zinc oxide is obtained, usually producing zinc of lesser quality than the hydrometallurgical process. Zinc oxide treatment has much fewer applications, but high grade deposits have been successful in producing zinc from zinc oxides and zinc carbonates using hydrometallurgy." Johntex\^talk 21:00, 3 November 2005 (UTC)

tidal energy

How easily can tidal energy be adapted tot he lifestyles of average canadians?

• Our article on tidal power includes a chart which mentions proposed tidal power projects in Canada. You may also be interested in wave power, hydroelectricity, and maybe even alternative fuel and Hubbert peak theory. Johntex\^talk 21:07, 3 November 2005 (UTC)

Earth sciences, naming and history.

I have talked a little about this on the talkpage of Earth science, the question is basically: Who named this science and why? The reason I ask, is because I think this is bad naming and here is why:

• Geo-logy basically means the same thing as earth-science. Science is Latin for "knowledge", logy is Greek for "Word", both words have been used widely to describe professions that "study things". Ge(o) means The Earth, and is Greek also. Imagine using a name like terralogy and geology, not as synonyms. It is perplexing.
• From a historic view, I think, geology is obviously supposed to be the "all-embracing term for the sciences related to the planet Earth." Geology may have started with the study of rocks, but the study of rocks gave us understanding of the inside workings of the Earth, that had been hidden from us. Then we see, how the inner part of the Earth interacts with the outer part, which we have studied somewhat longer, because of accessibility. This all effects the Earth, the fusion inside it and the weather outside it. Realization of this, should have expanded the definition of Geology, not made it a subcategory. A subcategory of itself infact :P

Geology (earth science) is fairly new to us, so I guess this is to be expected, but no one seems to know why the naming is like this or the reason behind it. Hope someone can help, thanks. --Friðrik Bragi Dýrfjörð 20:33, 3 November 2005 (UTC)

Geo does not mean Planet Earth. It means a piece of earth (ie: a rock or some soil). Therefore, geology is the study of rocks and soil. Earth Science (which I used to hear referred to as Natural Science) is the set of sciences that study the planet (such as meteorology). Kainaw 21:38, 3 November 2005 (UTC)

According to the Geology article, it means "the earth". Just as in Geography (notice, Earth is written with capital E). So I do think you are wrong. Please, also note, that Earth science is also called geoscience. --Friðrik Bragi Dýrfjörð 23:45, 3 November 2005 (UTC)

Geo comes from the Greek work ge (the "o" is used for the conjunction with the suffix). It means rock or soil. The Greek word Gaea means "planet Earth". While both start with a "g" and have an "e" in them, they are not similar in a Greek sense (even "Greek" has a "g" and "e" in it). So, it is a bit of a stretch to assume ge and Gaea are interchangeable.

Ignorance about ge has led many to think that it is the Greek word for our planet. (I said ignorance, not stupidity. I mean that many people just don't know Greek.) So, geo has been abused with improper words, such as geoscience. It is similar to the use of virii. With a basic understanding of Latin, you would know that virii is in no way a plural form of virus. If enough people use it incorrectly, the incorrect use will become correct. For example, the word "ain't" is now in most dictionaries even though any English teacher will tell you that it is incorrect. Kainaw 00:33, 4 November 2005 (UTC)

Thank you very much, this will also help me with a problem in my language. I checked dictionary.com, and is says there, "[Medieval Latin gelogia, study of earthly things ...]", so I still think this is very confusing. Surely, "study of earthly things" sounds as broad as "earth sciences". Perhaps I am being too picky :-) --Friðrik Bragi Dýrfjörð 01:33, 4 November 2005 (UTC)

Frequency of eye colors in the US

Hi there! I'm looking for information on relative frequency of eye colors in the USA, specifically the pacific northwest if that information is available. For example, what are the 10 most common eye colors? In what order? This is tricky, as my research has shown me that eye color is often a racial trait, in the sense that people of one descent might be much more likely to have one eye color than people from elsewhere. I've read the Eye color article, as well as googled all over, but if this information is available somewhere, I'd love to have it. If anyone has any ideas on where to look further, I'm happy to do the work, I just want the info and have run out of search ideas. Thanks! - CHAIRBOY (☎) 23:23, 3 November 2005 (UTC)

hexagons

I am looking for the formula to determine the size of a hexagon that could be stacked to cover a particular sphere size

Your question is too vague. What do you mean by "stacked to cover"? You could take one hexagon and wrap it around a sphere. You could take a grid of them. To make a real sphere without warping them, you'd need pentagons too (like a Bucky Ball). Kainaw 23:40, 3 November 2005 (UTC)

• When Kainaw mentions a "Bucky Ball", he is referring to Fullerene. Our article on Fullerene states

"In mathematics, a fullerene is a trivalent convex polyhedron with pentagonal and hexagonal faces. Using Euler formula, one can easily prove that there are exactly 12 pentagons in a fullerene. The smallest fullerene is C₂₀, the dodecahedron. There are no fullerenes with 22 vertices. The number of fullerenes C_2n grows rapidly with increasing n = 12,13, ... For instance, there are 1812 non-isomorphic fullerenes C₆₀ but only one of them, the buckminsterfullerene alias truncated icosahedron, has no pair of adjacent pentagons."

The term "Euler formula" is referring to one of the formulas of Leonhard Euler. However there are several at Euler function (disambiguation) and it is not immediately obvious to me how any of them relate to this quesiton. As Kainaw says, some clarification of your question would be helpful.

If you are trying to ask "For a sphere of a given size and a certain number of hexagon's how big would the hexagons need to be to cover the sphere?"

If so, then you might like to know that the surface area of a sphere of radius r is: $A=4\pi r^{2}\,$

The area of a regular hexagon of side length $a\,\!$ is given by $A={\frac {3}{2}}a^{2}\cot {\frac {\pi }{6}}={\frac {3{\sqrt {3}}}{2}}a^{2}\simeq 2.59808a^{2}.$

The area of a regular pentagon with side length a is given by $A={\frac {5a^{2}}{4}}\cot {\frac {\pi }{5}}={\frac {a^{2}}{4}}{\sqrt {25+10{\sqrt {5}}}}\simeq 1.72048a^{2}$

You might be able to derive a formula to figure out from this how big the hexagons and pentagons would need to be, given the size of your sphere. Keep in mind that the length of the side of the hexagon will be the same as the length of the side of the pentagon.

If what you want to know is specific to the case of the dodecahedron, then that article shows that the area A and the volume V of a regular dodecahedron of edge length a are:

$A=3{\sqrt {25+10{\sqrt {5}}}}a^{2}$

$V={\begin{matrix}{1 \over 4}\end{matrix}}(15+7{\sqrt {5}})a^{3}$

See also [[[Polyhedron]], Polygon, and Geodesic dome. Good luck, Johntex\^talk 00:43, 4 November 2005 (UTC)

paternity about ABO blood groups

case with mismatching ABO blood antigen in parents and one of their offspring the father is O+ ,mother is A+ and the daughter is B+ if it is possible I want to know the chances and possibilities is it mutation , or what because the girl lock gust like her father.

Universe Expansion and Contraction

I just read an article concerning the possible discovery of a supermassive blackhole at the center of our galaxy. And that sparked my curiosity about wether our galaxy is expanding or contracting?

I know that all galaxies of the universe are moving away from each other, Expanding, at equal speeds, and that as a whole the universe is in fact expanding. But then there are blackholes, such as at the center of our galaxy, that are so dense with matter that the gravitational force is pulling in surrounding planets and stars like a cosmic whirpool. This would be a form of galactic contraction, right?

Also where does the matter and energy go? Scientists say that it completely disappears, because no light can escape a blackhole. Could these be the sites of new universes, turning the dimensions inside out to create new alternate, and invisible (to us) worlds?

I would enjoy any guesses or information you may have.

thanks- brian

In this area of physics, you will find all kinds of nutty theories (I even wrote a whole paper to disprove that gravity exists). The universe is assumed to be expanding because we are moving away from most things and most things are moving away from us. If everyone is moving apart, it must be expanding. The issue is: how do we know we are moving apart?

Where does the matter and energy go? Well, matter and energy are different forms of the same thing (like ice and water). That's how we get nuclear power. So, where does the goop go? The latest theories are that it is broken up and emitted as X-ray energy around the edge of the black hole.

Also, the black hole doesn't suck everything up. Matter that is far enough away will be affected by it, but not sucked up. Kainaw 00:52, 4 November 2005 (UTC)

I'm not completely sure what Kainaw means, by "broken up and emitted as X-ray energy", but I think he might be referring to Hawking radiation, which I neglected to mention in my answer below. That's yet another answer about what happens to stuff in black holes, it eventually comes back out. (However, for a black hole with more than the mass of the sun, "eventually" means something like 10⁵⁰ times the current age of the universe.) -- SCZenz 01:23, 4 November 2005 (UTC)

There are three separate issues you bring up. One is the expansion of the universe, which you can read about in the Dark energy article; it's actually mostly unrelated to the behavior of black holes and the dynamics of the galaxy, so I won't discuss it further for now. (But of course I'll give it a shot if you ask more questions.)

The second is whether the galaxy is contracting because of the big black hole in the middle. The answer, I believe, is that if it is it's doing so extremely slowly. Most of the stars in our galaxy are in stable orbits around the center, and won't collapse into the center any more than the earth will fall into the sun.

The third is what happens to stuff that goes into a black hole. One answer is that, from the view of an outside observer in the universe, things falling into a black hole will take an infinite amount of time to even fall through the event horizon; it's strange, but true. Thus, wherever the stuff that falls into a black hole goes, it isn't there yet. Another answer is that it just sits at the center, as part of the singularity. A third answer would be that, well, we have no idea and there's no way to find out. It's hard for physicists to make predictions about things we can't possibly verify experimentally.

I hope that helps. Ask more if you've got more questions or need something clarified. -- SCZenz 01:20, 4 November 2005 (UTC)

Upload and download content on a website

Hi -

I'm creating a new website, and I want to have a section where people can upload and download source code and files, kind of like SourceForge.net. Are there any free resources/templates/guides or whatever that can show me how I could do this?

Thanks! Mary

GNU Savane is the software that the GNU Savannah [12], GNU's SourceForge-alike, uses. — mendel ☎    #    01:21, 4 November 2005 (UTC)