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December 4

Guppy

My guppy that i think is a female has a pointy think sticking out of its but lol and i know its not poop because its been there a long time what is it? thanks --Sivad4991 03:37, 4 December 2007 (UTC)

Can you describe this "pointy thing" with more detail? It would cut down on guessing and specious answers. 70.57.229.74 04:43, 4 December 2007 (UTC)

Have a look at this [1] page and see if it helps. Richard Avery 15:20, 4 December 2007 (UTC)

Processor Cooling

My heatsink has a fan on its right side, would it be beneficial to put a fan on the left side also (mounted onto the heatsink) or would it be better to put it on one of the other sides or top? Thanks —Preceding unsigned comment added by 76.167.132.90 (talk) 05:13, 4 December 2007 (UTC)

I would be most efficient if the airflow goes in the same direction, so put one on the other side with the same orientation as the original. However, are you sure that your processor need an extra fan? --antilived^{T | C | G} 09:47, 4 December 2007 (UTC)

Trying to overclock the processor as high as it goes, so I want to keep it as cool as possible without spending a lot of money on a cooling solution (like water cooling). Thanks for the reply —Preceding unsigned comment added by 71.106.34.15 (talk) 16:12, 6 December 2007 (UTC)

Little fishes

What kind of little fishes school at the surface of the water near the bank in a river in subtropical brackish water and appear to breath air? (At a distance of 10 feet or so this activity appears to be bubbles coming from the bottom.) Is this behavior because the water does not have enough oxygen or is this some type of social or other natural behavior of the fish? —Preceding unsigned comment added by 71.100.1.143 (talk) 05:31, 4 December 2007 (UTC)

Bubbles? Schooling in a single place? Sounds like they're spawning. SamuelRiv 08:27, 4 December 2007 (UTC)

Individual fishes remain separated by 4 to 6 inches. Stop at the slightest move I make although I'm a tremendous 20 feet away.

Many fish feed on insects at or just above the surface of the water. Shooting on along that thought, you might want to see our article about archerfish.

Atlant 14:08, 4 December 2007 (UTC)

They are not archering.

Some extra information would be helpful. How big are these 'little fishes', one or two centimetres? or smaller. Where, geographically, are you talking about? In the meanwhile, subtropical brackish water is likely to be low in oxygen if the water is warm. In these circumstances some species of fish do come to the surface to try and augment their blood oxygen level. This may account for the disturbance you have seen. Richard Avery 15:15, 4 December 2007 (UTC)

Lat. 27. Water Temp. 72 Air temp 82. They are 1 to 2 inches long.

A picture is worth a thousand words. Someguy1221 20:17, 4 December 2007 (UTC)

The wiki did not come to mind until I was home. I shall return to the spot when it warms up (has dropped to the low fourties over night) and take pictures galore.

one scientist's take on evolution

I just spent another useless hour googling for this: I remember once reading in an interview with some brain/intelligence researcher where he stated a piece of opinion that went something close to "The biggest evolutionary leap lies within mankind". He was talking about differences in intelligence and illustrating his opinion that the difference between the most gifted humans and averagely gifted humans is far greater than that between the average human and other primates. I have googled off my finger-tips several times over now, but I just can't seem to find it online who that researcher may have been? I dorftrottel I talk I 10:17, December 4, 2007

I remember hearing something about this on a science podcast once, maybe in relation to Artificial Intelligence (and the singularity) too in a Raymond Kurzweil kind of way, but it isn't him...I even tried to Google search your problem myself, as everyone tells me that I seem to be able to find out anything, but alas it is a real stumper! I will be interested to see if someone has the answer. Maybe when people in North America wake up. I keep thinking of James D. Watson! So sad. There was just that report in the news the other day about Chimpanzees beating college students at short-term memory tests too. Good luck! P.S. Not that people in North America are smarter, just that a majority of them read English and like to come to the the Wiki! Saudade7 13:02, 4 December 2007 (UTC)

Here's the short-term memory story. And an important note to that study was that the chimps were faster in their recall abilities, but no more accurate. So saying "they had better short-term memory" isn't precise enough to say exactly what the study concluded. And I highly doubt it was Watson. He usually just makes controversial claims about race and intelligence.--droptone 13:28, 4 December 2007 (UTC)

The chimps were faster at entering their responses - but no more accurate. That could be that the humans were being overly cautious or something. What was impressive was further down that article where they started to reduce the amount of time for which the numbers were flashed onto the screen. At four tenths of a second, the chimps were still doing quite well when the humans were failing utterly. That might mean that their visual system is more acute. I don't think these tests show anything about intelligence. SteveBaker 13:34, 4 December 2007 (UTC)

Just to say that I was just kind of throwing out ideas...I didn't read that chimp story very carefully, I just read the headline and skimmed. And I don't actually think that Watson said it, I was just saying that it made me think of him given his recent public comments when I was in London. I'm sorry if what I said sounded purposefully misleading or wrong. I really hope you find out. Take care. Saudade7 19:37, 4 December 2007 (UTC)

The BBC TV news showed some video of the chimps performing - DAMN! - they were fast! It was quite utterly amazing that such a complex task could be done that fast. They started off teaching the chimps the numbers 1..9 and scattering the numbers at random across a computer screen. The game was for the chimp to use a touch-screen to touch the numbers in ascending order (as each one is touched, it disappears). Then they'd flash the numbers up - for some amount of time - then write white squares over where the numbers had been. The game is the same, touch the white squares in the order of the (now concealed) numbers. Finally, they'd leave out some of the numbers - so you might have 1,2,4,6,7,8 and 9. That's quite a hard task when you only see the numbers up there for less than half a second. It was easy to see that the chimps were both faster (MUCH faster) and more accurate than the humans. (What's more, they were doing this for treats - and the chimp was casually eating with one hand and playing the game with the other!) But I'm still not convinced that this is a demonstration of intelligence - dexterity and 'photographic' memory - yes, but IQ, no. I could easily program a dumb old robot arm with a webcam to beat both chimps and humans...and such a machine would have no intelligence whatever. SteveBaker (talk) 01:55, 5 December 2007 (UTC)

I don't think it was supposed to be about IQ (nebulous as that is), what was supposed to be amazing was that Chimps outperformed humans in an area of cognition (is this the word I want or is it too specific? 'using their brains' is what I mean) and that this could happen was pretty dismissable until now. After all, you can program a computer to calculate arithmetic considerably faster than chimps and humans, but it would still be amazing if young chimps were faster and more accurate at arithmetic than humans. Skittle (talk) 09:57, 5 December 2007 (UTC)

Yeah - I agree. I think it would be surprising if there weren't quite a few mental skills that Chimps have that can beat us. I'm just dubious about attaching this "intelligence" tag to what they do. After all, what they are doing isn't so different than (say) dogs doing scent tracking - but we don't put that down to intelligence because it's clearly sensory and motor skills...well, so was the chimp test. SteveBaker (talk) 04:39, 6 December 2007 (UTC)

Thanks for the replies, will keep looking then. ¶ dorftrottel ¶ talk ¶ 07:48, December 5, 2007

Iranian nuclear video

In reports about Iran's nuclear program, the TV news often shows a clip where there's some sort of large ductwork on a floor with a gap where you can see an orange flame moving right-to-left. What is that apparatus doing? --Milkbreath 12:03, 4 December 2007 (UTC)

Can you find a link to a video on YouTube or YahooNews or something that shows this object? Saudade7 13:11, 4 December 2007 (UTC)

I found one on BBC World News, but it's not a direct link. You have to go here and click on "Pictures from inside an Iranian nuclear facility". The apparatus appears at 35 seconds in. --Milkbreath 14:54, 4 December 2007 (UTC)

Here's an attempt at a direct link:

mms://a113.v373744.c37374.g.vm.akamaistream.net/7/113/37374/1.0/clipdownloads.bbc.co.uk/realmedia/news/media/avdb/news/world/video/134000/nb/134442_16x9_nb.wmv

Thanks goes to Firefox plugin UnPlug. How do I make it an ordinary link, btw? —Bromskloss 15:40, 4 December 2007 (UTC)

I don't think you can make a direct link with something that doesn't start with "http://" etc. - this link has to have another program open to view it. It is kooky but it worked! I don't know what that thing is however. Good luck. Saudade7 19:32, 4 December 2007 (UTC)

They are using gas centrifuge technologies for doing the separation of the necessary isotopes. One assumes that this entails vaporizing the uranium and keeping it gaseous as it passes through successive enrichment stages. The boiling point of Uranium is around 4100 degrees C. So I guess that could easily be one of the centrifuge heaters...but who knows? Maybe the factory just gets kinda chilly in the winter? SteveBaker 15:54, 4 December 2007 (UTC)

I don't think so: The gas centrifugation is done with uranium hexafluoride which has a boiling point lower than water. 193.171.121.30 19:05, 4 December 2007 (UTC)

Remember that even though the media focuses primarily on the centrifuge facility (of which to my knowledge there is only one picture on the 'net of the insides), there are actually many facilities and plants required for their nuclear program. Anyway, I've seen some of those photos before from a trip made by the FARS news agency, and I believe it is of the Uranium Conversion Facility at Isfahan, at least judging from the color scheme and the orange staircases. See this group of slides for more pics. I don't know a huge amount about the many processes and equipment necessary to convert yellowcake into uranium hexafluoride, but some idea of some of the ways it is done can be gleaned from this document (a DOE-produced handbook of things not allowed to be exported to Iraq in 1996, specifically the chapter on uranium conversion technology). --24.147.86.187 (talk) 19:01, 9 December 2007 (UTC)

Emotional music

I'm trying to understand why most people have such a strong emotional response to film music (the kind you get in blockbusters and Disney movies). Why do we loose control of our emotions when hearing overwhelming violins and a few timbals? Not sparing myself for scientific experimentation, I rented a Hans Zimmer CD and I'm getting the expanding lungs, tingely heart thing as I type this so the film is not needed for the music to work. Why is it so effective? Keria 15:26, 4 December 2007 (UTC) and I have to add insistant wind instruments to the list.

In the case of music-for-film, it's easy to explain. Human memories are stored 'holistically' - we don't remember things the way a computer does by tucking one memory away in a little box with a label on it. Instead we remember by connecting every little bit of information with every other little bit. This makes it impossible to hear the music without (possibly subconsciously) recalling the movie it was attached to. This is sometimes very annoying...but it's how our brains work. Consequently, I cannot listen to the "Dance of the Sugar Plum Fairy" without thinking of chocolate with nuts and raisins in it because the tune was used for a particularly memorable series of UK television adverts a few decades ago. So I presume, the music is evoking the memory of (and emotions relating to) the movie. SteveBaker 15:47, 4 December 2007 (UTC)

By "film music" I only meant the type of music. I guess you could call it a certain type of classical music (the only example I can think of would be Carmina Burana). In the example of Zimmer, I haven't seen any of the films yet the music as a strong emotional impact. I'm pretty sure, for example, that it increases my heart rate, which feels like it's being crushed yet is all tingely at the same time; eyes go moist etc. This doesn't happen with most music. I can be excited and appreciate a good rock record but it hasn't the same direct emotional impact (maybe I'm wrong in calling it emotional). I guess this might happen with martial music too. Keria 15:59, 4 December 2007 (UTC)

This is a phenomenon that a lot of composers use, not just Hollywood composers. It is created by playing a chord of three notes (a triad), and then playing some other chords and notes that are dissonant to the original chord (called the root). This dissonance creates an uncomfortable feeling among the listeners. Eventually the composer then inserts a chord that will resolve or complete the root chord. This resolving chord may be a fifth or a seventh usually. This resolution to the dissonance creates a feeling of satisfaction and even euphoria for the listeners. For a more complete explanation of this, look at the wiki article called Seventh chord, with special attention to the section entitled "Dominant seventh". Saukkomies 16:09, 4 December 2007 (UTC)

It's not necessarily the music per se. You can listen to the same music on CD, radio or in a concert hall and not be affected by it to the same degree, or at all (although you might). It's the combination of the on-screen action with exactly the right music at exactly the right moment, that does the trick. This is not a new idea; for centuries, composers have been commissioned to write incidental music to plays (such as Grieg's music for Ibsen's Peer Gynt, Bizet's music for Alphonse Daudet's L'Arlésienne, Mendelssohn's music for A Midsummer Night's Dream, and hundreds of other examples). Stage managers cottoned on very early in the piece to the fact that audiences had a greater emotional reaction to the play when music appeared at judicious intervals to counterpoint the action; which would encourage patrons to come back and back, ie. put bums on seats. And of course, it's the entire basis of opera and modern day musicals, and try to imagine Swan Lake with dancing but no music. This doesn't help explain why it's so effective, but to show the idea has been around a lot longer than the movies. -- JackofOz (talk) 22:52, 4 December 2007 (UTC)

Level of inflammation determines speed of healing process?

Hi. Generally speaking, as an exercise question only. Suppose someone has a sprained foot. The body's natural healing process is to make the tissue surrounding the injury site inflamed. Thats called Inflammation. So, the patient takes Ibuprofen, a non-steroidal anti-inflammation drug. As I understand it, the body's purpose in making inflammation is to generate the replacement of injured tissue. The inflammation triggers this process, right? So, suppose patient A does take ibuprofen, and patient B doesn't (assuming the same kind of injury) I would imagine patient A will take longer to heal than patient B. Because patient A's inflammation will be less, and so the molecular replacement mechanism will be less intense, and stretch out over a longer period of time. Patient B will experience more pain, the inflammation will be more, but the injury will heal faster, because the repair signals are stronger. Right?

Thanks! —Preceding unsigned comment added by InverseSubstance (talk • contribs) 17:01, 4 December 2007 (UTC)

As noted at Inflammation#Inflammatory_disorders, not all inflammation is beneficial. Whether inflammation will help or hinder healing in any particular case is a medical question which should be directed to your doctor. The reference desk does not give medical advice. Dragons flight 19:47, 4 December 2007 (UTC)

There have actually been a number of studies on this, like this one, which found no significant increase in post-operative recovery with increasing dosages of anti-inflammatory drugs. Of course, these studies were operating only on approved dosage levels. Someguy1221 20:06, 4 December 2007 (UTC)

compass needle

what is the meaning of the phrase "needle point north to south" although a needle has two ends, how would we know which end is towards north and which is towards south?193.251.135.124 17:12, 4 December 2007 (UTC)

By convention, compasses are constructed such that the end that points north is marked in some way, often by being painted red. MrRedact 17:37, 4 December 2007 (UTC)

If I had to guess, I suspect that compasses were invented by people who lived in the Northern hemisphere and who didn't know that the South Pole even existed. For them, it pointed toward the North Pole - the back end pointed towards nothing in particular. SteveBaker 21:17, 4 December 2007 (UTC)

The compass was available well before most people had a concept of a globe in mind, and so it is doubtful whether those people even concieved of a "Pole" at all. I suspect there was a time when it was seen more as "one end points towards the cold lands and the other end points at the hot lands", at least in the early times. Dragons flight (talk) 21:25, 4 December 2007 (UTC)

For what it's worth, the compass was invented around 1000 and reached Europe around 1300. The idea of a Spherical Earth goes back to ancient times. More info on the general topic at History of navigation. The page on Christopher Columbus puts it, "the Earth had generally been believed to be spherical since the 4th century BCE by most scholars and almost all navigators". Pfly (talk) 21:59, 4 December 2007 (UTC)

Indeed. It's in our article, but in the interest of it becoming more widely known: Columbus' great idea was not that the world was round. His great idea was that the world was significantly smaller than it was then thought to be, and that he could thus sail all the way to Asia by going west. In this he was entirely mistaken, and was saved from mid-ocean starvation by running into the New World. Algebraist 22:26, 4 December 2007 (UTC)

{fact} Known certainly. Widely known and accepted by most scholars? I'd question the reality of that during the say the 12th century. Pre-renaissance there was a lot of old wisdom that wasn't exactly well known. Dragons flight (talk) 23:21, 4 December 2007 (UTC)

I too thought that statement was probably going too far -- but in a hurry I used it anyway -- the basic idea I was aiming for was that as the use of the compass spread through Europe, circa 1300-1400 or so, the people most likely to find them useful and practical would be navigators of the open seas (perhaps a rare breed at the time), who would probably already be familiar with celestrial navigation and methods of determining location that presumed a spherical planet. Just a minor tangent to the OP's question. Also, it amazes me that exploration voyages such as the Norse to Greenland and North America were done without the aid of compasses, relying on dead reckoning, measurements of latitude, and celestrial navigation. In any case, it may be difficult to determine how widespread the idea of a spherical Earth was in the late Middle Ages. The people most likely to make practical use the concept, sailors and navigators, tended to leave very little written record back then. Another grey area is in the three centuries between the compass's invention in China and its introduction to Europe. I know very little about what the Chinese and Muslim sailors of the Indian Ocean thought about the sphericity of the world -- though Medieval Muslim scholars were world's ahead, so to speak, than their European contemporaries on such things. But if we're talking about Europe, we're looking more at the 1300s and 1400s, by which time I think even among scholars -- at least scholars who cared to swell upon such topics -- the sphericity was becoming well established. Still I agree the statement on the Columbus fact was rather sweeping. Pfly (talk) 03:43, 5 December 2007 (UTC)

See Flat Earth. The early Christians were (as ever) dubious scholars, and no-one knows what the common people thought, but a recent study of medieval concepts of the sphericity of the Earth noted that "since the eighth century, no cosmographer worthy of note has called into question the sphericity of the Earth." And don't forget that the Polynesians achieved far greater (and much earlier) navigational feats than the Norse. Algebraist 16:55, 5 December 2007 (UTC)

ammonia

why ammonia is a gas even though it has three polar bonds? 122.163.139.129 19:12, 4 December 2007 (UTC)

One reason (or at least a devil's-advocate for your idea) is that the bond dipoles somewhat cancel each other, making the molecule as a whole less polar than "lots of N–H bonds" would suggest. DMacks 19:40, 4 December 2007 (UTC)

(ec) The polar bonding between ammonia is not nearly as strong as between water molecules. Firstly, oxygen is a much more electronegative than nitrogen, so the bonds are much more polar. Secondly, a water molecule has two lone pairs and two partially positively charged hydrogen atoms, whereas an ammonia molecule has one lone pair and three such hydrogens. Now, consider that a hydrogen bond can only be made between a lone pair on a partially negative atom (such as oxygen or nitrogen in these molecules), and a partially positive hydrogen. Since water has two pairs and two hydrogens, each water molecule can hydrogen bond to four other water molecules, and form a very strong nearly continuous lattice. (Indeed, at room temperature a water molecule is bonded to 3.6 other water molecules, on average.) An ammonia molecule can also make four hydrogen bonds, but the average over a large group cannot be four, as they contain disproportionately many hydrogen atoms to lone pairs. At best, a volume of pure ammonia could have each molecule make only one two hydrogen bonds. Combine this with that afformentioned weaker polarity, and the cohesive force holding ammonia molecules together is much weaker than in water. Someguy1221 19:42, 4 December 2007 (UTC)

The ammonia molecule is also closer to planar than a water molecule, which weakens its polarity further, thus weakening simple dipole-dipole interactions. I'll spare you the quantum mechanical reasoning for this. Someguy1221 19:47, 4 December 2007 (UTC)

Uhh, if I remember correctly, isn't ammonia sometimes a liquid? I remember, when we did experiments at my school, the ammonia was in the form of a liquid, at room temperature. Thanks. ~AH1^(TCU) 23:02, 4 December 2007 (UTC)

It can be liquid if stored at low temperatures and/or high pressures. It can also be dissolved in solution (ammonia is quite soluble in water), or dissolved as ammonium salts. It is also a product of many common chemical reactions. Someguy1221 (talk) 23:08, 4 December 2007 (UTC)

The "liquid ammonia" you used at school was almost certainly a solution of ammonia in water. You'll probably recall that the stuff smelled pretty strongly — that was the ammonia gas gradually evaporating out of the solution. —Ilmari Karonen (talk) 01:15, 8 December 2007 (UTC)

Gasoline-methanol blends?

From methanol:

The use of methanol as a motor fuel received attention during the oil crises of the 1970s due to its availability and low cost. ... As a result of its low price, some gasoline marketers over-blended.

How inexpensive can methanol be? How much would a gas station profit from over-blending? I mean, methanol has to be synthesized from simple organic molecules. The prices of these materials would also rise during an oil crisis because they are also fuels. Chemical synthesis adds to the costs of methanol. How could an over-blender profit from over-blending? If methanol is so cheap and abundant, why don't big companies build methanol burners to power their big factories? -- Toytoy 19:50, 4 December 2007 (UTC)

As of 2002 it cost 50 cents a gallon. However, this is the cost at very low levels of production (relative to global oil consumption). Someguy1221 19:56, 4 December 2007 (UTC)

The subsections on "production" and "automotive fuel" may also be enlightening. Methanol is not (primarily) derived from crude oil, and so its price isn't really tied to the 1970s oil crises. Over-blending builds the profit margin by substituting additional cheap materials for expensive ones. The section on "automotive fuel" (among other places in the article) notes that methanol is corrosive, damaging both metal parts and rubber seals. I'd think this a major reason that methanol burners aren't in vogue, and Someguy's note about production level's impact on cost is worth noting, too. Methanol may not be economically feasible if scaled up to crude oil demand levels.

As for profits, I'll pull numbers out of a hat for example purposes. I'll use $3/gal gasoline and $1/gal methanol. Pure gas costs $3/gal. The gas station decides that no one will notice their little "this gas contains methanol" sticker and substitutes 5% methanol without adjusting the sale price. They're now charging $3/gal for what's only worth $2.90/gal, pocketing the extra 10 cents on every gallon. Unscrupulous Gas Station X then decided to overblend to 10% methanol, charging $3/gal for $2.80/gal product. UGSX can even drop their sale price below the regular blenders (to, say, $2.95/gal) and still haul in a higher profit margin -- at the expense of their customers' engines. — Lomn 20:08, 4 December 2007 (UTC)

I wasn't aware of methanol as a gasoline additive, but we do have an article on Methanol_fuel. If it's like ethanol, my understanding of it being bad for engines is that this is merely a myth. You'll still find plenty of old timers who're convinced it's harmful to the engine, but I don't think this is really true today, if it ever was. Friday (talk) 21:21, 4 December 2007 (UTC)

Methanol/ethanol are solvents the designers of 1970's and 1960's engines did not plan for, and in a vehicle of mine, the blended alcohol destroyed the plastic float in the carburetor. Myth? I don't think so. Edison (talk) 22:47, 4 December 2007 (UTC)

Ethanol most certainly does destroy some OLD engines. It has three properties that are bad:

1. It dissolves rubber. So any car older than about 25 years that still has it's original rubber seals in the fuel path is in trouble. Even 10% ethanol ("E10") is enough to do this - and I can tell you that the classic car club I run has seen a MASSIVE increase in problems with various rubber seals since E10 was introduced into Texas. Retrofitting with modern seals fixes the problem - but for those who absolutely must keep their cars completely original, this is a major blow.
2. Ethanol conducts electricity - gasoline doesn't. At 10% (E10) it doesn't seem to be a problem - but it's anticipated that if/when we go to E20 or E25 in a few years time, then some gas gauge 'sender units' will misread or fail completely - as will some electric fuel pumps that are cooled by the gasoline. Again - not a problem for modern cars - bad news for classics and clunkers.
3. The combustion by products of high-ethanol mixtures are pretty acidic and will attack non-synthetic engine oil. So switch to synthetic and your problems are over - except that a very few old cars (of which my '62 Mini is one) use engine oil to lubricate the gearbox and synthetic oils aren't so good at that job. How big a problem that will be - I have no clue.

So yeah - it's mostly not a big deal - but the dissolving of rubber seals is absolutely real - and I have the rotted out 2 year-old seals to prove it.

I haven't heard of polythene parts in carb floats being destroyed yet - and I'm inclined to think this is a myth - but since my Mini has one - I'm going to keep a close eye on it! The '62 Mini has a float chamber that regulates the flow into the carb with a plastic float. If it jams in one direction, the engine is starved of fuel and stops. If it jams in the other direction the gasoline is over-pressurised and squirts out of an overflow hole in the float chamber - landing on all sorts of hot engine parts...it's quite exciting really!

SteveBaker (talk) 01:38, 5 December 2007 (UTC)

For anyone interested in ethanol-petrol blends, there's been a lot of hype and controversy about this recently with the recent launch of a 10% blend combined with the governments plans to mandate the introductions of such blends. New Zealand has a large number of used import cars, largely from Japan (which is rather late to the ethanol blend 'party' and isn't going to require all new cars to be compatible with E10 until 2010 and I think doesn't have much or any use of ethanol blends at the moment [2]) and the average age of the vehicle fleet is something like 12 years. Most imports are not carried out by the manufacturers so there are complicated liabity and COI (it's obviously in the manufacturers interest to claim most imports are unsuitable) issues etc. In any case, most manufacturers are reluctant to certify many of their imported cars as being suitable for anything greater then E3 (3% ethanol) while the government wants E5 and E10 and believes many vehicles should be fine. Some links which may be of interest [3], [4] & [5], [6], [7], [8] & [9] Nil Einne (talk) 11:05, 5 December 2007 (UTC)

Is it safe to say that gasoline blends with 10% methanol OR ethanol are not harmful to modern cars? Friday (talk) 15:26, 5 December 2007 (UTC)

I would say that 10% ethanol is OK for any car made in the last 20 years. Given the potential liability issues, it's hard to imagine how E10 could be sold in the USA if that were not the case. Here in Texas, ALL gasoline is E10 these days. But Nil Einne's evidence says otherwise. 'Harmful' is a tough word to use here...if E10 were to cause your oil seals to degrade after (say) 200,000 miles - is that "harmful"? I have less confidence with saying that is the case for Methanol. Switching to sythetic motor oil (which is a good idea anyway) is a wise thing to do - but it doesn't seem to be 100% necessary. It'll be a few years before we know for sure. SteveBaker (talk) 04:34, 6 December 2007 (UTC)

telescope type

Hi. I saw a telescope in the glass display case facing outside a store window. I want to know what type of telescope it is: refractor, reflector, or catadioptric. Sorry, I don't have an image, but if you want I might be able to upload one taken earlier. This telescope is about 4 inches in objective diameter, although the tube is about half an inch thick. It seems to have an objective lens, although it is about a centimetre behind the front of the telescope. The eyepiece is at the back of the tube, but sticks out of the tube vertically, sort of like in a Newtonian, further in front than the back of the telescope, but at the back. The finder seems to be a red-dot or reflex, but I'm not sure. It is computer-controlled, and has no counterweight. It's a Celestron. I estimate the focal length at f/5, but I'm not sure. I'm usually sort of a telescope "expert", but now this one confuses me. This is why:

refractor characteristics

• objective lens
• eyepiece at the back of telescope
• relatively small total size

reflector characteristics

• eyepiece jutting perpendicular from main tube
• relatively short focal length
• in-tube mirror may be needed to place the eyepiece there

So, any ideas to what type it might be? About how much would it cost if it were new and regular price? Thanks. ~AH1^(TCU) 22:57, 4 December 2007.

The people at the store ought to at least know what model number is written on the thing, if not the detailed specification. If you can't go back there and ask them, why not telephone them and ask? --Anonymous, 23:10 UTC, December 4, 2007. (UTC)

Possibly a Maksutov-Cassegrain or similar design? They are relatively short for their aperture. (Because the light path is folded, the real focal ratio is slower than the length would suggest, i.e. slower than the f/5 you estimate.) -- Coneslayer (talk) 00:36, 5 December 2007 (UTC)

It is probably a four inch Matsukov or Schmidt-Cassegrain. Those are about 300-400 dollars. You should go to the Celetron website and look up the pictures Website or on the Meade site. Saudade7 00:49, 5 December 2007 (UTC)

To tell what sort it is, look at the front of the scope. If there's a plain sheet of glass, it's a reflector. If there's a round object supported by a sheet of glass, it's a catadioptric of some sort. If there's a round or rectangular object supported by one or more wires, it's a reflector. --Carnildo (talk) 01:11, 5 December 2007 (UTC)

I think it's their 4" Maksutov-Cassegrain (NexStar 4SE). The eyepiece and prism looks like it's built into the rear plate which hides the actual path out the center of the rear mirror. It's actually an f/13 scope. --DHeyward (talk) 17:56, 5 December 2007 (UTC)

Hi. Uhh, how could you try to find out what is is if you don't know what it looks like? First of all, the telescope actually isn't for sale, and it's more of a used items store than a telescope or department store. Well, I only know the telescope by looking at the images, and there is a lens visible but even when photographed head-on, it's hard to see anything other than the lens. I don't think it is a NexStar 4SE, for many reasons. First, the telescope tube is much closer to the mount than that. Second, the eyepiece doesn't just look close to the tube, the hole for the eyepiece atcually juts perpendicularly through the top of the tube, closer to the back than the front. Also, It was impossible to see someting that resembled that white circle in the centre of the lens, as only the front lens was visible at all when the telescope was photographed head-on. If you want, I could probably upload a photo sometime later today. Oh, and the photo might suit the article for Celestron, Telescope, and the one for whatever classification it is. Thanks. ~AH1^(TCU) 18:36, 5 December 2007 (UTC)

Hi. I uploaded the image so hopefully you might be able to tell what type it is.

Here's the image! There's a lens at the front. If you look closely the eyepiece juts from the tube.

Thanks. ~AH1^(TCU) 23:23, 5 December 2007 (UTC)

Okay, look at the end of the tube nearest the camera and you'll see a brand name: it appears to be NexStar. Look on the Celestron website and you'll see that they have two NexStar lines. The telescope in the photo looks very similar to the NexStar 114 SLT or the slightly larger NexStar 130 SLT. Presumably the telescope in the window is an older model that was replaced by one of these; of course the differences might be enough to significantly affect the price.

I note also that the telescope in the window is pointed the wrong way! That's the mirror end nearest the camera. --Anonymous, 00:14 UTC, December 6, 2007.

Hi. Um, the end nearest the camera actually has a hole, and a lens behind it. I know it's hard to see on this image, but my other images show that there is glass at the end of the tube closest to the camera. I can't see where it says NexStar, and I know that if it were a reflector, the end nearest the camera would be closed, but actually that end has glass, and you could see to the other end of the telescope if you looked at it head-on. Thanks. ~AH1^(TCU) 01:05, 6 December 2007 (UTC)

The lettering is at the top of the tube, above the double wavy line. As to the construction, obviously I haven't seen the actual thing, but that looks like a mirror mount, and the layout looks reversed compared to the images on the Celestron site and I cited. --Anon, 01:55 UTC, Dec. 6.

Hi. Actually, nevermind. I checked the Celestron's site using the Internet Archive's wayback machine. The telescope seems to be a model from about 5 years ago, a NexStar 114. The new telescope doesn't really look like this, but the NexStar 114 from back then looks almost identical, although I can't tell if it's a GT or an HC. The new version sells for over $450, but the old one was probably cheaper, although I can't tell because the old version didn't have its price listed. Well, thank you all for helping me solve this mystery. Thanks. ~AH1^(TCU) 00:22, 7 December 2007 (UTC)

Mystery Vegetable

I bought some interesting produce from a stall outside a little shop, and I've worked out what everything was except for one root vegetable (my favourite was realising that the weird knobbly black things were chestnuts with complete outers). This root vegetable is white and about 30 cm long, 10 cm in diameter (with little tapering until the very end where it has a root which was not included in the measurements I gave). When cut it smelled like radish, and when nibbled it tasted like radish and had the same texture. I assume it's in the same family as radish, possibly it's just called 'giant white radish'?

Anyway, does anyone have any idea what this vegetable is? Thanks. Skittle (talk) 23:09, 4 December 2007 (UTC)

Could it be a Daikon? --TeaDrinker (talk) 23:13, 4 December 2007 (UTC)

Fantastic! (The introduction actually uses the phrase giant white radish :P If I hadn't thought I was suggesting something ridiculous, I could have searched the phrase) Hooray! Thanks TeaDrinker. Now, to learn! Skittle (talk) 00:18, 5 December 2007 (UTC)

Redirects are cheap. Giant white radish.  ;-) Dragons flight (talk) 00:23, 5 December 2007 (UTC)

Yes, but alas, the poor mangel-wurtzel has to make do with beet.... - Nunh-huh 00:28, 5 December 2007 (UTC)

Maybe you mean a Mangelwurzel? DuncanHill (talk) 01:25, 5 December 2007 (UTC)

No, I meant mangel-wurzel, the spelling which actually appears in my dictionary. Unfortunately a "t" got caught up in it. It's nice to know we have an article on my favorite strange vegetable, but it would be nicer if the redirect went from the wrong spelling to the correct one, rather than vice versa. :) - Nunh-huh 01:49, 5 December 2007 (UTC)

Those chestnuts did not have "complete" outers. When the chestnut falls off of the tree, it has a prickly husk about the size of a baseball ( about 100mm in diameter.) This husk is so prickly that you must be quite careful when you pick it up from the ground. The husk contains several of the covered nuts that you found in the market. You should use those nuts immediately instead of keeping them. roast them or boil them, or eat them raw. They may (and probably do) have insect eggs that will hatch into larvae that become evident if you keep them for more than about two weeks. This is not a health problem, but it is an aesthetic issue. take a look at this:

those nuts came from several of those prickly things. When they are still green the husks can be picked up carefully with your bare hands. They turn brown after about three days. At that point you will need either some good garden gloves or a high pain tolerance. -Arch dude (talk) 01:38, 5 December 2007 (UTC)

Whenever I see discussion of chestnuts, and eating them, I feel inclined to remind American readers that the tree and nut commonly called "chestnut" in the US is actually Aesculus hippocastanum, "horse-chestnut" or "buckeye", and can make you sick if eaten. I for one believed for years that the "chestnuts" we collected as kids were the same things one could "roast over an open fire". Essentially all the American Chestnut trees were killed by the Chestnut blight of the early 20th century. Just a friendly word of warning. Pfly (talk) 04:01, 5 December 2007 (UTC)

Yes, do not under any circumstances eat a buckeye. My comments were with respect to the Chinese chestnut which is now grown in many places in the United States. I have personally encountered trees planted in about 1945 in Tennessee and in about 1960 in Virginia. if you encounter a "chestnut" in the wild in North America, do not eat it. -Arch dude (talk) 02:25, 6 December 2007 (UTC)

I've actually been puzzling over this. When I said 'complete outers' I meant it; the shiny brown things were inside a shrivelled black layer, but the shrivelled black layer contained only one of them. I'm now wondering if they were water chestnuts, but I don't have much experience with water chestnuts except in certain take-away meals. I tend to think of water chestnuts as having a different texture and flavour, but perhaps that is only in the preparation? I boiled these and they tasted like chestnuts and had the same texture as roast chestnuts. Skittle (talk) 09:42, 5 December 2007 (UTC)

How can this thread POSSIBLY be complete without mention of the noble 'Conker'?!

British schoolboys have been using horse chestnuts (aka conkers) to play the game of Conkers since time immemorial. There is something wonderful about opening that shrivelled spikey green/brown husk and finding a beautiful, shiney smooth conker inside. Conkers were played obsessively when I was a kid in the 1960's. Truly great conkers (six'ers and better) were traded and competed in exactly the way the Pokemon cards are - the difference being that you could find your conkers lying in the street. Truly great, legendary twenty'er conkers were practically worshipped. People would give their lunch money just to be allowed some practice swings with such heroic nuts. The dozens of arcane and mysterious techniques for hardening conkers were passed on from father to son, from elder brother to younger. Debate over which techniques were fair - which acceptable - which worked and which didn't would consume all of our waking hours! The string could be improvised from a shoelace in an emergency - but the perfect, softest sting and the exact way to knot it was another subject for endless debate. People perfected their swings, complete with follow-through - with the verve of pro-golfers. SteveBaker (talk) 04:23, 6 December 2007 (UTC)

Um, I'd rather you'd passed on any experience you had of water chestnuts and chestnuts, how they are different from a culinary point of view and whether what I bought more closely resembles one or the other. I was not buying conkers. Skittle (talk) 18:55, 6 December 2007 (UTC)

Good, it would be immoral to buy conkers, totally contrary to the spirit of the game. DuncanHill (talk) 01:20, 8 December 2007 (UTC)

December 5

Company

What is the worlds largest company?thanks --Sivad4991 (talk) 00:14, 5 December 2007 (UTC)

Exxon Mobil is the largest by revenue, PetroChina is the largest by market capitalization. MrRedact (talk) 00:28, 5 December 2007 (UTC)

Walmart by revenue (among public companies) and by number of employees. Dragons flight (talk) 00:28, 5 December 2007 (UTC)

• This page says it's Exxon this year, with Wal-Mart at #2. I believe Wal-Mart is usually #1, but the oil biz is having a great time lately. I find the distribution of industries in the top ten interesting/depressing:

1. OIL: Exxon Mobil
2. Wal-Mart
3. OIL: Royal Dutch Shell
4. OIL: BP
5. CARS: General Motors
6. OIL: Chevron
7. CARS: DaimlerChrysler
8. CARS: Toyota Motor
9. CARS: Ford Motor
10. OIL: ConocoPhillips

--Sean 14:03, 5 December 2007 (UTC)

What's so interesting and or depressing about it? I would fully expect the top companies to be those with scalable advantage and wide appeal. Since car mfg, retail, and energy fall nicely into those two categories, it's natural that they top the list. What would be depressing is if the list were topped by Halliburton... --Jmeden2000 (talk) 17:32, 5 December 2007 (UTC)

Dear Sean, I too thought that the list you provided was self-evidently depressing. Our planet is (and we are) doomed! Saudade7 23:25, 5 December 2007 (UTC)

downhill,luge weight balance

i have a heated battle going on with a friend of mine on how to make our street luges faster.I,being slightly smarter than him had the idea of using physics to my advantage.I was wondering what would be the optimum center of gravity point. i was thinking about a 70-30 ration with the 70 being towords the nose. or maybe a 80-20? —Preceding unsigned comment added by 67.8.167.136 (talk) 00:25, 5 December 2007 (UTC)

If you're trying to reduce friction, I don't think the weight distribution would matter much. The resistant force of rolling friction is proportional to the normal force, so the total rolling friction is going to be pretty much the same, regardless of how the weight is distributed. Stability considerations would probably outweigh any slight difference in rolling friction. And off the top of my head, I can't think of any other reason why a change in weight distribution would affect your speed. Certainly the force of gravity is the same regardless of where you are on the luge. Why do you think putting more of the weight toward the nose will make the luge faster? MrRedact (talk) 00:42, 5 December 2007 (UTC)

because of those little wooden race cars that i made in the boy scouts that went down a sloping track and when i put more weight in the front it went faster. —Preceding unsigned comment added by Gotnse (talk • contribs) 21:13, 5 December 2007 (UTC)

Conventional wisdom is to put the weight as far back as possible, so the weight will stay on the sloped part of the track for a fraction of a second longer. --Carnildo (talk) 22:49, 5 December 2007 (UTC)

I thought the reason was to grab additional gravitational potential energy by starting off with the weight being higher up the track so the heaviest part of the car falls a greater vertical distance. But for a street luge this doesn't seem terribly relevent since the shape of the track is unknown. Some of the other techniques used by Pinewood derby cars might be relevent. But in the end, I can't imagine that anything other than reducing the friction of the wheel bearings would have much effect. SteveBaker (talk) 04:01, 6 December 2007 (UTC)

Those are the same idea. While a car with its weight in rear and a car with its weight forward are both on the slope, each's center of mass will fall the same distance over time. When the cars hit the flats is when you notice that the one with its weight in rear is still accelerating. That is, it had more GPE to convert to KE. — gogobera (talk) 08:06, 6 December 2007 (UTC)

Grab a heavy dumbell, and go do a couple of runs! Of course, you'll want to do several with the weight in each position, so you can average your results to reduce your uncertainty. My guess, for the record, is in consensus with the above: it shouldn't matter where the center of mass is. — gogobera (talk) 07:04, 6 December 2007 (UTC)

In fact, if you've had a course in physics (mechanics), you can draw up a simplified cart with wheels and a center of mass between them. You'll find that the normal force on the front wheel is proportional to (1-l/L), where L is the distance between the wheels and l is the distance from the front wheel to the center of mass. The normal force on the rear wheel is proportional to (l/L). Therefore, the frictional force, f, which is the sum of the frictional forces on the two wheels, doesn't change with respect to where the center of mass is. That is, (1 - l/L + l/L) = 1. If your two axels are the same, that is. I'd concentrate on reducing friction (good lubricant?) and drag (streamlined profile).

If the course levels out at some point before the end, placing the CM as far to the rear as possible (as high above that level point) might let you squeeze out a couple more meters/sec. — gogobera (talk) 08:06, 6 December 2007 (UTC)

I get very nervous about applying the standard "laws" of friction in these kinds of practical situation - the real-world situation rarely matches the "high-school" friction law that says that the frictional force is proportional to the mass and that's all. We had a thread about this a while back and I ended up going to a lot of trouble to show skeptics that this 'law' is only an approximation of the truth (and in many cases, a TERRIBLE approximation).

So if (to pick a purely hypothetical example) you had soft rubber tyres on these things - then changing the weight over the wheel alters how much the tyre deforms under the weight - and the continual flexing and unflexing of the tyre as it rotates eats energy and slows you down (this is one reason why you get worse gas mileage in your car with under-inflated tyres). If that were the case here (and this is only an example) - then moving the weight to the center of the luge might eliminate the flexing (a net win) - or distribute it more equally so that more tyres flex (making matters worse). If this 'flexional' loss were not a linear function of the weight over the wheel, there could very well be a reason to move the weight for or aft. Now, I may well be completely wrong - since probably street-luges use hard nylon wheels - but all sorts of parts of the luge might flex like that - you may have much more complex things going on than we can easily imagine. That's not to say that I know the answer - only that an over-simplistic treatment of the problem may produce seriously incorrect conclusions. I think our OP needs to do some controlled tests. SteveBaker (talk) 18:26, 6 December 2007 (UTC)

The factors that I remember being decisive from my days in the Cub Scouts: 1) Lubricate axles. 2) Streamline the shape. 3) Even more than the above, make sure the axles are perfectly straight & perpendicular to the direction of travel. Anything else will have the wheels dragging against the ends of the axle. Of course, I'm not sure how much of the above is applicable to downhill luge. jeffjon (talk) 14:56, 6 December 2007 (UTC)

Cold Chills

I have been trying to start the page for Cold Chills Does anyone know why we get chills when we listen to music that affects us deeply or when we have certain thoughts? Thanks,--DatDoo (talk) 02:06, 5 December 2007 (UTC)

We already have a shiver page; we probably don't need one for cold chills. We certainly don't want one called "Cold Chills", because that's incorrectly capitalized. - Nunh-huh 04:01, 5 December 2007 (UTC)

My bad brah...I wasn't really sure how to CAPTALIZE it. do you know how to change??? The shivers page has no info on getting chills from music or inspiration or anything like that.--DatDoo (talk) 04:26, 5 December 2007 (UTC)

The solution would be to add that information to that page, not start another page! Yes, Cold Chills could easily be moved to cold chills, or if you want, I'll delete it at your request and you can add any information you want to shiver. - Nunh-huh 04:30, 5 December 2007 (UTC)

I think the OP is not talking about the medical condition but about what the German Romantics (poets, philosophers, biologists etc.) called the "Heilige Schauer" or "Holy Shiver". I wonder if we already have a page on it...Nope - so it is free for you to build/write! Immanuel Kant, Johann Gottfried Herder, Friedrich Schiller, Johann Gottlieb Fichte, Friedrich Wilhelm Joseph Schelling, Johann Wolfgang von Goethe, Wilhelm von Humboldt, even Georg Wilhelm Friedrich Hegel all wrote things but you will probably need to read some German. Good luck. (By the way, if you Google it, the first hit where the guy is relating it to only courage in battle and sports...he's wrong. It's more subtle that that. It's about the Sublime). Saudade7 23:45, 5 December 2007 (UTC)

The OP isn't describing the reflex response of shivering which "is a bodily function in response to early hypothermia in warm-blooded animals". DatDoo is instead referring to that emotionally triggered response which also results in goose bumps but without the cold stuff. hydnjo talk 05:20, 6 December 2007 (UTC) addendum: Accordingly, the cold chill article has been started to address this difference. hydnjo talk 05:29, 6 December 2007 (UTC)

Poorly Defined Triple/Critical Points?

I have seen a number of examples on wikipedia and even in journals of triple points given as "triple point temperature" as in Tetrafluoromethane. What use is this without the pressure of the triple point? Shniken1 (talk) 03:47, 5 December 2007 (UTC)

...left as an exercise to the reader? ;-) Someguy1221 (talk) 04:21, 5 December 2007 (UTC)

...Probably under standard pressure if it is left undefined. Or if the article is talking about an environment in that environment 213.107.86.173 (talk) 21:22, 11 December 2007 (UTC)

Unconscious sleep?

Are we unconscious when we are asleep? —Preceding unsigned comment added by Cockysht (talk • contribs) 11:38, 5 December 2007 (UTC)

Is there any reason why Unconsciousness which is a link from Unconscious doesn't help? Seems pretty straightforward to me... Nil Einne (talk) 12:22, 5 December 2007 (UTC)

I'd have to say no. They're two different things. To be unconscious means that you can't be roused. --Milkbreath (talk) 12:31, 5 December 2007 (UTC)

Not necessarily. A person who faints is unconscious but can usually be aroused pretty quickly. Being asleep (which sometimes happens involuntarily, like when watching TV) and being unconscious for other reasons (eg. fainting) are two different ways of being non-conscious. -- JackofOz (talk) 13:41, 5 December 2007 (UTC)

(after e/c) I'd have to say yes. You are not conscious when asleep so.... But (like so many questions) it's probably just a question of definition. The OED doesn't say anything about "can't be roused" for "unconscious", indeed it defines sleep as "The unconscious state or condition regularly and naturally assumed by man and animals, during which the activity of the nervous system is almost or entirely suspended". But the OED is not a medical dictionary, which would no doubt be much more specific.--Shantavira|^{feed me} 13:44, 5 December 2007 (UTC)

"Unconsciousness" / "being unconscious" is a physical state e.g. being in a coma. The "Unconscious", on the otherhand, is an area of one's psyche that is not directly accessible to thought or introspection...e.g. in Freud's psychoanalytical theories. One is physiological; the other is psychical. (Which is not to say that Freud and I aren't materialists). Saudade7 23:57, 5 December 2007 (UTC)

Yes because we are 'not knowing' (the meaning of unconscious)--TreeSmiler (talk) 02:23, 6 December 2007 (UTC)

Ah, but do you not know, or do you just not remember? Hard to be sure. I'm fairly certain there have been times I have been asleep, but still able to think and be aware that I'm thinking (not dreaming), and even remember what I was thinking about when awakened shortly afterwards. --Trovatore (talk) 02:27, 6 December 2007 (UTC)

You are not aware of the outside world: therefore you are 'unconscious'--TreeSmiler (talk) 02:29, 6 December 2007 (UTC)

That's a rather restrictive interpretation. If you're aware of anything, external or not, that constitutes consciousness, in the sense that we're most interested in (for example, in the question of whether a machine can be conscious, we don't really care whether the machine's perceptions correspond to any external reality, but only whether the machine has perceptions of any sort). Anyway I strongly suspect that's what the original poster was asking: Are we aware while sleeping? --Trovatore (talk) 02:35, 6 December 2007 (UTC)

I quote from our article:

Consciousness is a characteristic of the mind generally regarded to comprise qualities such as subjectivity, self-awareness, sentience, sapience, and the ability to perceive the relationship between oneself and one's environment. It is a subject of much research in philosophy of mind, psychology, neuroscience, and cognitive science.--TreeSmiler (talk) 02:42, 6 December 2007 (UTC)

Do you disagree with this definition?

Note that it's not, strictly speaking, a definition; it tells you something about consciousness, but does not precisely demarcate what is and what is not consciousness. Nevertheless, it's pretty accurate -- it's a list of a bunch of things that can be called consciousness. It doesn't imply that they all have to be present for a state of mind to be considered conscious -- any one of them is sufficient. --Trovatore (talk) 02:46, 6 December 2007 (UTC)

Is DNA unique to Earth?

What the arguments (or evidence if it exists), for and against the idea that extra-terrestrial life will be made up of DNA os we know it? Do we expect some variance, or a completely new system of life? What are the scientific implications of being able to interact with life not made up of DNA? Fenton Bailey (talk) 12:54, 5 December 2007 (UTC)

Today, no one can say for sure. If the panspermia theory is true, DNA arrived here from "out there" already in operational condition, so we may eventually find DNA other places as well. If DNA evolved here on earth, it may still exist in other places if it is a "pretty-good" encoding scheme (as it seems to be); in this situation, it (or something very much like it) may have independently evolved on other life-bearing planets as well. It's also possible life elsewhere evolved other, completely-different coding schemes for their equivalent of a genome that doesn't involve anything like a four-base double helix. For example, if we are eventually replaced on this planet by self-replicating artificial intelligences, they are unlikely to use DNA as a storage medium.

Atlant (talk) 13:21, 5 December 2007 (UTC)

I am afraid this calls for speculation. In anycase would the basic building blocks / storage of alien life even have any greater impact when it came down to interaction or communiction? You require sapience for communication anyway, as for interaction it very much depends on exactly what you intend to interact with. It is a very open set of questions with very speculative answers. Lanfear's Bane | t 13:23, 5 December 2007 (UTC)

• It would be interesting to know if anyone has developed a theoretical genome encoding not based on DNA or RNA (which works, chemically). Such an alternative would answer the question of whether DNA/RNA are the only way to do it. The fact that all the diverse life on Earth is DNA/RNA-based makes me wonder whether it's unique in some way. --Sean 13:49, 5 December 2007 (UTC)

There have been theories about using proteins for storing information.--Stone (talk) 13:58, 5 December 2007 (UTC)

Looking back on the history of mankind the most important consequence of an alternative biochemistry of aliens would be that you can't eat them! Humans are only able to do a limited set of transformations in organic molecules and therfore digestion and reusing the molecules of aliens will not work. Bacteria are by far more capable and the would recycle the organic molecules.--Stone (talk) 13:56, 5 December 2007 (UTC)

We have no good reason to expect that extra-terrestrial life will be based on DNA. Jack Cohen and Ian Stewart warn against this sort of restrictive and unimaginative thinking in their book Evolving the Alien. We don't even have a good reason to expect that extra-terrestrial life will be made of matter. However, there is a point beyond which extra-terrestrial life-forms may be so "alien" that we cannot meaningfully interact with them or even recognise them as living beings at all. Gandalf61 (talk) 16:23, 5 December 2007 (UTC)

Keep in mind that even if aliens do have DNA, it may be in a different form than is commonly found on Earth. See DNA#Alternative double-helical structures for other ways DNA can be structured other than the familiar double-helix. Also, some organic molecules tend to be left- or right-handed for life formed on Earth. For example, sugars tend to be right-handed, and proteins and amino acids tend to be left-handed. But alien life may have the opposite handedness for some or all of those things, which could make it hard for us to get nutrition from each other's foods. See Chirality (chemistry)#Chirality in biology. So, even if the aliens have DNA, they may still be rather unlike us in other details.

But, regarding your main question, it wouldn't surprise me at all if advanced aliens had transfered their minds from organic brains into mechanical/electronic devices. It would allow them to survive without aging and they could "sleep" during the long interstellar voyages to other worlds. As for interacting with them, well, it might take some time, but some form of communication should be possible, though we may never totally understand each other. -- HiEv 18:47, 5 December 2007 (UTC)

It's also interesting that adenine, a precursor to the nucleoside adenosine, is found all over the solar system and is feasibly created in widespread interstellar dust clouds. It's cool to learn that the buidling blocks of known life can be found well outside planet Earth... — Scientizzle 21:34, 5 December 2007 (UTC)

There are several reasons for suspecting alien life to be chemically similar to life on Earth, and it mostly revolves around what is easiest to do, chemically. Amino acids, nucleic acids, and other simple organic molecules are "easy" to make in many anoxic environments, and some have even been found naturally in space. Further, any presently plausible life form has to compartmentalize itself to confine chemicals inside or outside, and in Eukaryotes, in different intracellular compartments as well. The "easy" way to do this is with water and an amphipathic lipid. This can be done outside of water, but not with anything that's remotely likely to form in an Earthlike environment. So with all of this, it's not to say that alien life is necessarily similar, or even that it's likely to be, but rather that on the conditions of planet earth, our current almost certainly the easiest way for life as we know it to happen. Someguy1221 (talk) 19:05, 5 December 2007 (UTC)

• I recommend this recent article in Scientific American. In addition to chirality (noted above), and changes in amino acids (which could be done with DNA, just not the sort of DNA that we have), this is the proposal that I find the most intriguing: arsenic instead of phosphorus. The result would be stunningly similar to DNA, except that the creatures would find phosphorus to be just as poisonous as we find arsenic. --M@rēino 19:21, 5 December 2007 (UTC)

Taxonomy

Is there a classification of animals and plants strictly according to the chemicals and the amounts their body can produce? —Preceding unsigned comment added by 71.100.1.143 (talk) 14:13, 5 December 2007 (UTC)

I'm not aware of such. It may not be a very useful way to classify- down at the molecular level, a lot of what's going on inside you, and inside, say, corn, is the same. Friday (talk) 16:05, 5 December 2007 (UTC)

On the other hand it may render relationships such a predator and prey more obvious.

It would be too hard to classify like that too. How could we classify dinosaurs with this system? Our classification system is based on common ancestry, which provides insight to how the animals evolved, and how recent a common ancestor existed between two or more living beings. 64.236.121.129 (talk) 18:22, 5 December 2007 (UTC)

Certainly to hard for manual classification. Automated techniques on the other hand such as Optimal classification need only a list of entities and their chemicals.

Junk DNA Part 2

I was wondering if the what's referred to as junk DNA could be the coding for genes that we carry but do not express? Could they be for example some of the genes that your great grandmother maybe had green eyes or your grandfather was really good in math and science, but these traits were not expressed in you, however, they are carried and could be expressed in your child? —Preceding unsigned comment added by 68.120.83.149 (talk) 15:22, 5 December 2007 (UTC)

Yes and no. So-called Junk DNA is not usually in a form which translates to protein. DNA which codes for a protein has three base pair combinations called codons which code for specific amino acids (which combine in folded chains to form protein). So while much of the junk DNA used to code for something, mutations have accumulated in it so it no longer works (in the sense there are no recognizable codons anymore). The term "junk" however should not be taken to mean it is useless. There is also some reason to think the non-coding sections alter the expression of genes. Other hypotheses have suggested it acts as spacers or buffers to add robustness to mutation. There is more extensive discussion on the junk DNA article. --TeaDrinker (talk) 17:43, 5 December 2007 (UTC)

Might I ask a question to the answer; with such variation in sheer size between DNA between different species, how does Evolution treat and discuss this? 81.93.102.185 (talk) 18:15, 5 December 2007 (UTC)

Four paragraph discussion in an online book, with some references. Some interesting articles: Cell size as a link between noncoding DNA and metabolic rate scaling, Economy, speed and size matter: evolutionary forces driving nuclear genome miniaturization and expansion.
--JWSchmidt (talk) 19:53, 5 December 2007 (UTC)

Do you mean the article Evolution, or the field of evolution? Assuming you mean the latter, there are various theories based in evolution regarding the existence and utility of junk/noncoding DNA (see those articles for many of them.) It is also known that birds, for example, tend to have less noncoding DNA than most mammals and reptiles. For example, chickens have about as many genes as humans, however the human genome is nearly three times the size of the chicken genome (see here). It was thought that evolutionary pressure is stronger on birds to lose any unimportant noncoding DNA because evolution strongly favors lighter designs for flight, but more recent research suggests that the reduction in genome size may have happened during dinosaur evolution because smaller genomes meant smaller cells and an elevated metabolism. See JWSchmidt's comment above and Dinosaurs provide clues about the shrunken genomes of birds". It could be that a smaller genome in dinosaurs created the possibility of bird evolution. Also, as the article notes, non-flying birds today have more noncoding DNA than flying birds, so having more noncoding DNA probably has benefits too (as I mentioned above). Does that answer your question? -- HiEv 20:07, 5 December 2007 (UTC)

Human eye size

I have studies many people's faces, including my own, and one eye is always bigger than the other. In certain people this feature is more visible than in others. I want to know what causes this irregularity or asymmetry. I know that when I was little, I used to lay on my side while watching TV. Obviously this would have an effect on what eye the body considers more important, and then would adjust its size or position? Also, could it be that if you see closely the whole time (like reading, computer, etc.), the one eye might go back into the cage, and the other might become more pop-eyed? And that if you see far the whole time (like on farms or the countryside) that your eyes might be more equal in size? Just like a binoculars? Please tell me a) what you think subjectively about this, b) what scientific research was done about this and what science says about this, and c) what you think objectively about this (ie give your unbiased opinion based on the facts). — Adriaan (T★C) 15:38, 5 December 2007 (UTC)

If you are concerned about buphthalmos, please seek professional medical advice. As for body symmetry, human bodies are not normally symmetrical. There are many studies that have shown better symmetry is linked to attractiveness. That implies that a lack of symmetry is common. -- kainaw™ 16:00, 5 December 2007 (UTC)

An interesting exercise that is very easy for those with Photoshop or equivalent is to take a photo of oneself (or anyone) where the subject is looking straight at the camera, and to create 2 faces: one with the left half mirrored, and one with the right half mirrored. The hair can be cropped or masked so it looks like the normal hairdo. The two faces often look like utterly different people. Edison (talk) 20:26, 5 December 2007 (UTC)

This is also the reason people find photos of themselves to be such terrible likenesses (NOBODY thinks their drivers license photo looks like them). We are used to seeing ourselves in the mirror - but that produces an image that's flipped left/right compared to a photograph. Just as mirroring a face renders it less recognisable - failing to mirror it when you're used to seeing it mirrored is also every-so-slightly "wrong".

Many years ago, before there were PC's, I was writing a paint program for television studios and we had a very early colour document scanner. We had great fun stealing photographs of people's families from their offices, scanning them and very-subtly "damaging" them to make the people look every so slightly wrong. Since we had no colour printers back then, we had to use a hideously expensive gadget we had for taking large-format polaroid photos of a special CRT - but we could then re-insert the 'damaged' versions back into their frames. The trick was to 'damage' them just enough so they didn't look quite like the real person - but not so much that their owner could tell what we'd done. Mirroring the face was one trick we discovered - and moving one eye or one ear just a tiny fraction away from it's original position such as to make the faces just a little bit less symmetrical. Rotating the nose just a few degrees clockwise or anticlockwise, repositioning the hair out a quarter inch further down to create a 'low-brow' forehead also has a dramatic effect. Since the technology to scan, edit and print photos was unheard of back then, none of the victims could quite believe what had happened. Anyway - you can do very subtle things to a human face and make it wildly ugly or completely unrecognisable...it's another one of those ways in which humans see things in a manner that is completely unexpected.

SteveBaker (talk) 20:57, 5 December 2007 (UTC)

Interestingly, there has been some genuine peer-reviewed research into the effect of facial and body symmetry – or asymmetry – on perceived health and attractiveness. A number of researchers have found evidence that we find more symmetric faces more attractive. Our article on symmetry (physical attractiveness) has a number of interesting links. TenOfAllTrades(talk) 21:57, 5 December 2007 (UTC)

Something odd I saw on Discovery Channel

I'm hoping somebody can refresh my memory on this. I saw something on the Discovery Channel about 6 years ago about somebody working at Princeton who conducted this odd study where he placed analogue random number generator devices around various parts of the world that reported their histograms on an hourly basis; and he found that whenever there were catastrophic world events (such as 9/11), the histograms indicated that the random number generators were not being as equiprobable as you would expect from a random number generator. I think the point of the study was to investigate the claim that human moods could alter technology. It struck me as rather "out there", but since it was a peer-reviewable, falsifiable study that anyone could reproduce, I don't think it was unscientific per se. Anyway, I hope someone can refresh my memory as to the details; all I remember is that it was conducted by someone at Princeton. Is there an entire community of people who study this phenomenon in a scientific approach? --75.165.55.66 (talk) 16:57, 5 December 2007 (UTC)

Sounds like Global Consciousness Project. -- Finlay McWalter | Talk 17:00, 5 December 2007 (UTC)

Maybe this is it. (Actually, Princeton Engineering Anomalies Research Lab.) --Milkbreath (talk) 17:09, 5 December 2007 (UTC)

Not to be confused with the (interesting but fictitious) Hundredth Monkey Effect.--Shantavira|^{feed me} 18:08, 5 December 2007 (UTC)

If it's true - and if it can be reliably demonstrated then it's a little surprising that they haven't claimed their million dollars yet. SteveBaker (talk) 20:41, 5 December 2007 (UTC)

The Princeton Engineering Anomalies Research (PEAR) lab and the Global Consciousness Project (GCP) are actually somewhat related, though the PEAR lab has since shut down. Also, there are many criticisms of the methodology used, questions about some of the results, and attempts to reproduce some of the results have had a tendency to fail. While the research is interesting, and has claimed some results, the overall results have generally been overstated in the media and public discussions. The PEAR researchers have been offered the James Randi Educational Foundation $1 million prize if they could reproduce their results twice under controlled conditions (as SteveBaker mentioned above), and they have repeatedly refused to even attempt it (see here for example). All of this makes me doubt the results they have claimed.

Regarding the GCP, they claim that "global consciousness" somehow affects their randomly generated numbers, but instead it looks to me like they are cherry picking their data. For example, during the 2004 Indian Ocean earthquake that caused tsunami damage in 20 countries and cost over 200,000 lives, the CGP didn't show any significant difference (see the mean composite of all eggs graph here). In their own analysis of the event (seen here) they show almost nothing during that time of statistical significance (which they show as the blue line with "P=0.05" (5%) on their graphs; note also the arbitrary selection of where they start and end showing data, which affects significance). The only graph on that page that shows a significant change on the day of and following the quake is the final one, but that is merely a chart of the number of hits on their website. However, with things like this, it's usually the case that the hits are remembered and the misses are forgotten, which makes the evidence seem stronger than it really is. -- HiEv 21:03, 5 December 2007 (UTC)

Yes, I heard these guys (The Princeton Engineering Anomalies Research (PEAR) lab and the Global Consciousness Project (GCP)) on a few old Art Bell shows maybe a year or two ago (while I was doing dishes - always a good crazy show to clean house to); I think you'd have to subscribe to their show-downloads (like 6 bucks a month) on Coast to Coast but then you could download all 8-12 hours of the interviews. I am pretty sure they were on with Art and not the new guy George Noory who, as an interviewer, is a tad too fluffy, ADHD, and religious for my tastes. Saudade7 00:10, 6 December 2007 (UTC)

The existance of the Randi's $1 million prize is a great way to debunk a wide range of paranormal claims. Few people can come up with a believable reason to turn down a million dollars for a couple of day's work - and an underfunded college research group certainly cannot. So as long as the prize is still on offer, we may be reasonably confident that not one of these paranormal claims can be trusted. People who refuse to even try the test must not only be unable to demonstrate their effect - but also KNOW that they can't...nobody turns down a million dollars. SteveBaker (talk) 03:45, 6 December 2007 (UTC)

Buddha did :D -Shniken1 (talk) 04:06, 6 December 2007 (UTC)

Well, the issue with the Randi challenge (and the reason I guess he's so sure he'll never pay it off) is that as soon as something is provable and repeatable, it's not 'paranormal' in any real sense anymore. Personally, I agree with Randi that self-professed psychics and healers, etc. are either charlatans or deluded individuals, but anyone looking for the million bucks should accept the fact that they're just not going to "beat the system", because the system always moves. It reminds me of an essay by Bertrand Russell where he mentions that the reason many philosophers seem so weird and nonsensical is because as soon as something is proved empirically it becomes science and if it is proved theoretically it becomes mathematics. All that can be left has to be a little wacky. Matt Deres (talk) 18:16, 7 December 2007 (UTC)

No, winning the challenge does not invalidate the challenge. It only has to be "paranormal" as far as Randi is concerned at the beginning of the test. In at least one case (possibly more) he has offered to remove the word "paranormal" from the challenge due to people who said they refused to take the challenge because they didn't want to be associated with the paranormal and that they didn't think their claims were paranormal. Despite the offer to solve the potential applicant's objection, they still refused to be tested. In other words, that argument is just an excuse to avoid taking the tests. -- HiEv 05:39, 9 December 2007 (UTC)

December 6

F-35 questions

Looking at the recently released information of the F-35 engine failure in May, is it possible to install a ram air turbine on the F-35? Also, why is there no trainer version? And why no two-seat version? --Blue387 (talk) 01:10, 6 December 2007 (UTC)

You would probably do better asking over at the F-35 talk page, but if I was to guess I would say "weight concerns". Astronaut (talk) 01:59, 6 December 2007 (UTC)

I would actually say the science desk is the better place to ask, as it's much more heavily trafficked than most talk pages. Someguy1221 (talk) 04:06, 6 December 2007 (UTC)

Agreed. Talk pages are for discussing the article, not the topic of the article. -- HiEv 12:11, 6 December 2007 (UTC)

I don't think it's weight. They could quite easily take out a few hundred pounds of fuel to compensate - you don't need long range capability for training missions. No - the real reason is that it costs a lot of money to design, build and certify a two-seat version of a plane that's intended to be single-seat-only in actual mission usage. They might only ever make a dozen of the two seat version - which means there is no economy of scale. In the past, there was little choice in the matter since you had to have some way to teach people to fly the darned thing. On the F22 program, they planned some two seat varients - but cut them from the program to save money. For both the F22 and F35, it was decided that flight simulator technology was sufficiently good that pilots could go straight from other aircraft types (F16, F18) for which two-seat variants exist to flying solo in an F35 - with only simulator time used for the transition. Since they need good simulators anyway - it's much cheaper to do that than to design and build two-seaters that are effectively useless for actual missions. I was the lead graphics engineer for the F22 and F35 simulators - and it was quite a proud moment to understand the that simulators have attained to become so well accepted by the military. Incidentally, civil airlines are routinely allowed to have pilots transition from one aircraft type to another using "zero flight time training" (ie simulation) - and they've been doing that for at least 20 years. So the pilot on your next flight could easily be on his first ever trip in that kind of an aircraft! SteveBaker (talk) 03:30, 6 December 2007 (UTC)

I believe it's possible to get a complete type rating from simulator time alone. In a recent "Flying" magazine article, one of the regular contributors (a surgeon by trade) who only flies a twin engine Beechcraft, received his Boeing 737 type rating without leaving the ground. (Type ratings are all that is required for turbine and airplanes greater than 12,500 lbs beyond the "Airplane, multi-engine, land" rating. So to go from a twin engine, six seat, propeller Beechraft to a 4 engine boeing 747 is a type rating. No airline would let you fly it, but you can get the legal ability to do it and all you need is sim time). --DHeyward (talk) 04:14, 6 December 2007 (UTC)

Yes - from a multi-engine rating, I think it's possible. It's been a long time since I last did civilian simulation - but that's a much easier job than simulating a modern fighter. The fidelity of even a 20 year old 737 simulator is really close to 100% and training on a simulator is so much cheaper and safer than flying a real plane that flight hours logged in a sim are actually more valuable than on the actual aircraft. In the simulator you can toss up fault conditions, singly and in combination, fly at night and in fog, you can bring in other aircraft on converging or colliding courses and practice at airports from all around the world without going there...all manner of things that you can't possibly do in a real plane. SteveBaker (talk) 04:55, 6 December 2007 (UTC)

No two seat version, because that's what the F-22 is for. The F-35 is a smaller, STOVL version of the F-22 essentially. The F-35 is a smaller, navy fighter, while the F-22 is a larger airforce fighter. 64.236.121.129 (talk) 14:32, 6 December 2007 (UTC)

But there isn't a two seat version of the F22 either - that was to have been the F22B but it was cancelled in 1996 or so (probably when they saw how good our simulator was!) SteveBaker (talk) 18:08, 6 December 2007 (UTC)

Actually, the F-35 is a multi-service fighter (with distinct Air Force, Marine, and Navy versions) intended to fill a role separate from that of the F-22. For the Air Force, the F-35 fills a role akin to that of the F-16, while the Navy and Marines will use it to replace F-18s (though not the E/F Super Hornets). Only the Marine variant has STOVL capability. — Lomn 15:48, 6 December 2007 (UTC)

Anyway, not having seen a discussion of the RAT specifically, here's what I've dug up: The F-35 uses an IPP, or Integrated Power Package for auxiliary and emergency power, which seems to negate the need for a RAT. The article linked notes that the F-35 is moving towards "more-electrical" components like this one to save weight, improve reliability, and improve packing efficiency (that is, you don't have to put it where it can deploy into the airstream). I haven't run across the details of the May engine failure, though, so I can't offer much as to the specific implications for that incident. — Lomn 16:04, 6 December 2007 (UTC)

atomic number

how do they know how many protons are in an atom? How did Mendeleev know the atomic masses of the elements in his periodic table?70.171.229.76 (talk) 03:00, 6 December 2007 (UTC)

They have little teeny eyes

For seeing little teeny things

Like you need little teeny license plates for bees

With apologies to whoever it was that Larry Niven copied it from. --Trovatore (talk) 02:54, 6 December 2007 (UTC)

...oh, by the way, it actually is a good question, and I don't know the answer off the top of my head. It just made me think of the song. --Trovatore (talk) 03:03, 6 December 2007 (UTC)

The number of protons has to equal the number of electrons in an electrically neutral atom. So the question is really "how do they know how many electrons there are in an atom". Sadly, I don't know the answer to that either - but I bet it's a lot easier to answer! SteveBaker (talk) 03:05, 6 December 2007 (UTC)

Mass is easy. They used scales! They do a titration or something to know how much stuff there is and then weigh it. That mass divided by number molecules is the mass of the molecule. The number of protons would have been determined first ionising the atoms completely and finding their mass/charge ratio in a mass spectrometer Shniken1 (talk) 03:35, 6 December 2007 (UTC)

The periodic table was invented before the concept of an electron as a discrete particle. They didn't have mass spec or the ability to fully ionize heavy atoms. The original periodic table was based on shared chemical properties and increasing mass, not number of protons. For example, unreactive gases (e.g. noble gases) formed one column. They did have a rudimentary concept of valence based on how chemicals combined, so they could place alkali metals and halogens in their columns, etc. But the largest determining factor in the overall ordering of the original table was mass. Dragons flight (talk) 05:12, 6 December 2007 (UTC)

My point is that you can't use mass alone because you can't tell the difference between the mass of a proton and a neutron with any degree of precision. So if they had been using mass alone, they wouldn't have been able to tell the difference between (say) Pb²⁰⁵ and Tl²⁰⁵ (that's a bad example because lead-205 is very rare - I'm sure there are better examples) - and they'd have been unable to set things out neatly using mass alone. You need to look at how the elements react together to get an idea for valences - which in turn relates to the number of electrons/protons. However, you can almost guess where each element belongs in the table by examining it's properties - metals on the right, non-metals on the left. Reactivity rates increasing across the rows, similar chemistry down the columns... that's the kind of thing that would let you know if you had two elements in the wrong order...not mass. SteveBaker (talk) 17:57, 6 December 2007 (UTC)

Perhaps a better example would be tellurium and iodine, which have atomic masses 127.6 and 126.9, respectively. Sorting by mass puts them in the wrong order (compared to atomic number) due to a high natural abundance of the heavier tellurium isotopes, and indeed I believe they were originally switched on early attempts at periodic tables. However, examining their chemistry clearly shows that iodine is a halogen and belongs in group 7. --Bob Mellish (talk) 19:07, 6 December 2007 (UTC)

Mendeleev would have had no notion of isotopes or anyway to get elements in any masses other than the naturally occuring mixture. Natural masses gives you the right ordering for all but 3 naturally occuring elements. His insight was actually to arrange groups and predict gaps where elements hadn't been discovered based on chemical properties, but figuring out the overall ordering is easy on the basis of mass alone. Dragons flight (talk) 19:03, 6 December 2007 (UTC)

According the Wikipedia's article on Dmitri Mendeleev, he created the table from known atomic masses and properties (discovered by other scientists). In fact, his table was capable of predicting the masses of not yet discovered elements. You can read more about Mendeleev's Periodic Table. (EhJJ) 03:46, 6 December 2007 (UTC)

By shooting electrons onto a sample of the element in question, one obtains x-rays. The spectrum of these x-rays is composed of a continuous portion (bremsstrahlung) and characteristic lines. By measuring the characteristic lines the effective nuclear charge can be determined (the charge affecting the innermost (1s) electrons, generating energy levels similar as in the hydrogen atom, but at higher energies). The effective nuclear charge is approximately Z-1, where Z is the number of protons (and if this is not accurate enough, neighboring elements in the periodic system have always an effective nuclear charge differing by approximately 1, so you can make the measurements for many elements until you have a complete series up to the element in question). Icek (talk) 05:07, 6 December 2007 (UTC)

Another method is using the Geiger-Marsden experiment: The number of deflected particles from a "monochromatic" (all particles have got the same energy) alpha source is proportional to the nuclear charge if everything else (like the thickness of the foil in atomic layers) is equal. Icek (talk) 05:20, 6 December 2007 (UTC)

To determine relative atomic masses you make careful measurements of the relative masses of different elements as they participate in a range of different chemical reactions, then you apply the law of multiple proportions (that's not a great WP article, because it reads like a chunk from a textbook, but it does illustrate the law with various numerical examples). Chemists like John Dalton were determining relative atomic masses at the beginning of the 19th century, many years before anyone even postulated the existence of protons, neutrons or electrons. Gandalf61 (talk) 13:43, 6 December 2007 (UTC)

I'd like to draw attention to the fact that this edit providing the majority of the multiple proportions article appears to have copied it from this book, which is under cc-by. I'm not an expert at how to give the appropriate attribution, but something clearly needs to be done about it. --Tardis (talk) 16:41, 6 December 2007 (UTC)

How does the nuclear binding energy (mass defect) compare to the difference between proton and neutron masses? HRMS can pretty easily distinguish between different element combinations that have the same integral mass ("number of nucleons"), so given a nuclear mass with enough precision, could one determine what specific combination of protons and neutrons gives it? DMacks (talk) 18:29, 7 December 2007 (UTC)

For ²H, nuclear binding energy is about twice the ¹p⁺ vs ¹n⁰ mass difference, I guess this isn't gonna work in many cases:( Yup, two minutes in the library saves a lot longer and megabucks of lab-work. DMacks (talk) 18:33, 7 December 2007 (UTC)

ring finger

Why is it hard to stick only your ring figer up. or to do that thing from star trek where your fingers look like \\// .thanks--Sivad4991 (talk) 03:02, 6 December 2007 (UTC)

It's odd - but some people have problems with that and some don't. I can do both of those very easily. Another one is the ability to raise one eyebrow and not the other. Yet another is to have one big toe point upwards and the other downwards - then to switch them both - then to alternate rapidly between the two such that one toe is always up and the other down. I think it's simply that these are things that we never normally need to do - and therefore get very little practice at. I kinda suspect that if you don't do them as a kid, some neural pathways don't form - then it's very tough to learn how to do it as an adult. I know my son couldn't do the "Live long and prosper" Vulcan salute thing when he was 10 years old - but managed to learn how to do it. There are some of these things (like rolling your tongue into a tube) that have actually been studied rather carefully - but I have to say that the results aren't exactly convincing. SteveBaker (talk) 03:14, 6 December 2007 (UTC)

Another one, most people can pat their head and rub their stomach, but can't do the opposite. —Preceding unsigned comment added by Shniken1 (talk • contribs) 03:30, 6 December 2007 (UTC)

From ring finger, "It is the weakest of the fingers on the hand, as it shares a flexor muscle with the middle and little fingers. It is the only finger that cannot be fully extended by itself separately." This is as much as I suspected, "something wierd about muscles." Someguy1221 (talk) 04:08, 6 December 2007 (UTC)

fully extend - no but 'stick it up' - yes. SteveBaker (talk) 04:43, 6 December 2007 (UTC)

Place one hand on the underside of your forearm about 60% of the way toward the hand. Now open and close your other hand. You should feel the muscle base pulling the tendons that go up through your hand to manipulate your figures. (Your fingers are essentially moved by wires anchored in your forearm.) The muscles that move adjacent fingers are partly connected so when you attempt to close or extend one finger you often end up manipulating adjacent fingers. It is possible with training to significantly increase the degree of independent movement. Such training is a common element of some dance styles, particularly those from the Indian subcontinent. Dragons flight (talk) 05:22, 6 December 2007 (UTC)

I used to have problems moving my fingers independently but playing the piano helped me to 'train them to move independently although my ring finger and little finger still want to move together a bit. The same goes for playing a different tune with the right and left hands, it's very difficult but practice makes perfect. As for the patting your head and rubbing your stomach, I can do it both ways round although it takes some practice and coordination! Some people can also wiggle their ears but I've never been able to do that. I think a lot of the reason is that muscles are very weak unless they actually get used, as most people have no need to wiggle their ears or precisely control their little finger, we perhaps 'forget' or don't learn how to use them in the first place? GaryReggae (talk) 11:59, 6 December 2007 (UTC)

variable frequency drive

at the inverter section, what will happen if one of the igbt's component short out or opens? —Preceding unsigned comment added by 70.251.116.191 (talk) 04:08, 6 December 2007 (UTC)

What exactly are you talking about? Power supplies? Amplifiers maybe? It's hard to tell! SteveBaker (talk) 04:41, 6 December 2007 (UTC)

Any short in a transistor in the bridge circuits of a variable-frequency drive will usually blow a fuse (and maybe the "other" transistor in that half-bridge). It's harder to assess what will happen for an "open"; an already-running motor may keep running, but will commonly overheat. A stopped motor probably won't start on the remaining two phases. In either case, a good VFD will recognize that something is wrong and shut down.

Atlant (talk) 13:15, 6 December 2007 (UTC)

Overloading an IGBT is very likely to vaporise it and the surrounding circuitry, so that you will not be able to determine what caused the failure. Good luck if you are operating without protection. Graeme Bartlett (talk) 20:32, 6 December 2007 (UTC)

Vaporize? Not if it's fused properly. And I speak from direct experience here.

Atlant (talk) 23:49, 6 December 2007 (UTC)

cosmic microwave background radiation

Are the photons of CMBR gravitationally lensed? —Preceding unsigned comment added by 203.192.230.107 (talk) 08:39, 6 December 2007 (UTC)

Cosmic microwave background radiation mentions this and cites a published article from 2006. --JWSchmidt (talk) 14:17, 6 December 2007 (UTC)

I do belive they are but the mass distribution between here and the edge of the observable universe is approximately even so it all almost cancels out with a few anomalies.Thomashauk (talk) 21:36, 11 December 2007 (UTC)

Faraday cages

I've read some Wikipedia articles related to Faraday cages. I'm not sure if I have understood correctly but, do they mean it is impossible to build a Faraday cage that cancels every incoming electromagnetic wave (because each skin depth nullifies a definite range of frequencies)? --Taraborn (talk) 11:57, 6 December 2007 (UTC)

A given Faraday cage is effective over a range of frequencies. At the high frequency end, it's (usually) pretty simple: the size of the openings, if any, must be quite small compared to the wavelength you're trying to exclude; the rule of thumb is to keep openings smaller than a quarter wavelength. At the low frequency end, I'm not quite sure, but it seems to me that there's no problem excluding the electric field but that the exclusion of the magnetic field requires increasingly good conductivity as the frequency goes lower and lower (because the Faraday cage must conduct an opposing current, creating an opposing magnetic field). A superconductive Faraday cage would probably exclude the magnetic field right down to DC (see the Meissner effect), but non-superconductors must have a practical lower limit (combined with an attenuation factor).

I'm not sure "skin depth" comes into play directly, though.

Obviously, I hope someone comes along who can offer a more-concrete answer to your question.

Atlant (talk) 13:24, 6 December 2007 (UTC)

Thank you for your response. Let's see if somebody else has something to add. --Taraborn (talk) 14:52, 6 December 2007 (UTC)

Skin depth comes into play with the low frequency end. If your shield has only a few skin depths of thickness then some fields will penetrate, so for audio frequencies you may have to use thick layers of metal. Graeme Bartlett (talk) 20:38, 6 December 2007 (UTC)

Plasmon frequency again?--TreeSmiler (talk) 02:37, 7 December 2007 (UTC)

Purple sky

A few days ago, the sky turned purple, during the day. Why is this? It was not sunset.

(Sorry to link to this place but it was exactly what was seen). Photo from flickr 147.197.229.134 (talk) 14:36, 6 December 2007 (UTC)

Purple is a mixture of red and blue. Towards dawn or dusk, the sunlight is red but the sky away from where the sun is shining is blue. Generally, these colours stay in their own parts of the sky and don't bother each other - but just the right kind of a layer of thick cloud between you and the sunset can diffract and mix the light together - resulting in reddish sunlight and blue from the sky being mixed into this purplish colour. SteveBaker (talk) 16:54, 6 December 2007 (UTC)

This photo was quite obviously taken at night (buildings are dark with indoor lights coming through the windows). My guess is that it's a photograph of lightning. (EhJJ) 20:26, 6 December 2007 (UTC)

I'm the photographer of that photo (my site logs pointed me here!), and I can tell you it was taken at 4pm on the 4th December, in mid-Norfolk, UK. It was dusk at the time - and certainly no lightning! I took a similar photo at a similar time almost a year ago too: link to more purple sky.--DeKay01 (talk) 22:07, 6 December 2007 (UTC)

So why did our questioner say "It was not sunset"?? On December 4th in London, sunset time is 3:58pm and the photo was taken at 4pm. At sunset, no other explanation is needed than the one I gave above - red+blue=purple. QED. SteveBaker (talk) 23:42, 6 December 2007 (UTC)

I interpreted the questioner to mean that the photo is an example of what he saw, but perhaps not exactly what he saw. The IP seems to come from the Univerity of Hertfordshire and my UK geography is woefully lacking - is that near mid-Norfolk, where our photographer was? --LarryMac | Talk 23:52, 6 December 2007 (UTC)

A similar picture taken of a lightning strike. (EhJJ) 01:28, 7 December 2007 (UTC)

Seems to me like SteveBaker is probably right about the reason. Sorry if it seemed like I was jumping to a conclusion, but it looks a lot like this photograph (right) that I took a few months ago; the image the OP linked is in no way taken in the middle of the day. (EhJJ) 01:28, 7 December 2007 (UTC)

The photo the OP linked to was mine, taken at 4pm on the 4th December. However, the OP seems to be using it as an example of what he saw - so he may well have seen the same sort of thing earlier in the day. Mid-Norfolk is about 100 miles N/NE of Hertfordshire. --DeKay01 (talk) 07:40, 7 December 2007 (UTC)

Obviously, the further north you go, the earlier sunset will be - and the longer it will last. The 3:58pm sunset time on Dec 4th was what I looked up for London. Also, sunset is defined as the time the upper rim of the sun drops below the horizon - there will be a lot of red light in the sky for a long period before that. The amount of cloud cover serves to diffuse the light - so it might not be obvious to people observing the effect that they are actually looking at the consequences of the sun starting to set. I think the OP may merely be surprised that the sky was actually turning red (behind the clouds) so early in the day. SteveBaker (talk) 16:33, 7 December 2007 (UTC)

How well do battery electric cars perform under cold and hot temperatures?

Topic says it all. 64.236.121.129 (talk) 15:56, 6 December 2007 (UTC)

I find very little discussion of significant problems with nominal temperature extremes. I would hypothesize that, should efficiency problems be severe enough, it would be no big deal to heat or cool the battery compartment along with the passenger compartment. — Lomn 16:14, 6 December 2007 (UTC)

My understanding of lead-acid batteries is that they have trouble delivering a large current in cold temperatures (think of starting your car on a cold day), but the cold temperatures do not cause permanent damage. Hot temperatures, on the other hand, do not cause immediate problems, but do shorten the lifetime of the battery. I don't know about other battery types in this regard. -- Coneslayer (talk) 16:39, 6 December 2007 (UTC)

(old answer deleted - I didn't notice "electric cars"!) SteveBaker (talk) 16:57, 6 December 2007 (UTC)

As far as cold temperatures are concerned, you get mixed messages. This page claims that there are no problems and quotes a study done by REV Consultants. The REV Consultants page explains that the test was on a battery heating system to keep the battery from getting too cold. So, you have one person saying that batteries work just fine in the cold and another marketing a battery heating system so they don't get too cold. -- kainaw™ 17:20, 6 December 2007 (UTC)

If you'll accept a practical example, the battery pack in the Toyota Prius hybrid car is air-cooled using a fan. So Toyota's designers clearly considered that higher temperatures were bad for the long-term health of the battery. The problem on the cold side is that aqueous electrolytes all have some freezing point and the amount of charge in a battery can affect that; for example, for a lead-acid battery, the electrolyte becomes more- and more-pure water as the battery is discharged, leading to the possibility of the battery freezing at a mere 0°C if the battery is dead flat.

Atlant (talk) 17:28, 6 December 2007 (UTC)

Doesn't the Prius have a Nickel-Metal Hydride battery? Heat is definitely bad for NiMH batteries it reduces cycle live (hence the reason you're supposed to keep them cool and why fast chargers can be bad) and increases self discharge. On the other hand, performance does drop with temperature and although you can use them below freezing you generally can't charge them. At least according to [10] (which discusses several batteries types) Nil Einne (talk) 12:40, 11 December 2007 (UTC)

Yes, NiMH for the "hybrid" battery in the stock, current-production Prius. (Plug-in mods vary all over the spectrum from Lead-Acid to Lithium Ion.) The Prius also contains a conventional 12V lead-acid cell for ordinary 12V needs, but I certainly didn't intend to imply that the Prius's main energy-storage battery was lead-acid, I just used that chemistry as the most-obvious example of a battery that has problems in the cold.

Atlant (talk) 13:54, 11 December 2007 (UTC)

Floppy McDonald's Fries

How can one make fries floppy like at McDonalds? I know they're supposed to be crispy or whatever, but I like them when they're floppy. What goes "wrong" to make 'em good 'n' floppy? --Seans Potato Business 16:18, 6 December 2007 (UTC)

Less frying time gets you softer fries. More time makes em cripsy. Friday (talk) 16:24, 6 December 2007 (UTC)

For home fryer use, a single fry is a good way to make floppy fries. For crispy-but-not-burned, a double fry is advocated -- once to cook, and once at a higher temp to crisp. Professional jobs use a different method, but I forget what it is offhand. — Lomn 16:32, 6 December 2007 (UTC)

It is called Blanching. --Mdwyer (talk) 20:21, 10 December 2007 (UTC)

BTW, as far as I'm aware most fries you can purchase are pre-fried so you usually only need to do this with fries that you cut yourself (although I'm sure you can get fries which are not pre-fried). Similarly for that matter most commercial fries are pre-fried too, the actual McDonalds/whatever chain only has to fry them once Nil Einne (talk) 12:32, 11 December 2007 (UTC)

I suspect that some floppy fast-food fries are the result of them sitting under a heat lamp for a while before they are served. -- Coneslayer (talk) 16:37, 6 December 2007 (UTC)

Does Ball Lightning have an charge?

Can it be affected by magnetic fields? 64.236.121.129 (talk) 18:32, 6 December 2007 (UTC)

Since the nature of ball lightning remains unknown, no definitive answer can be given to these questions. — Lomn 19:00, 6 December 2007 (UTC)

It's not at all clear that ball lightning is in fact a real phenomenon. They have not been produced artificially - and the conditions under which they are supposed to have arrived in nature is poorly described. There is no reasonable way in which a ball of electrical charge could be stable for seconds to minutes as claimed. I'm utterly horrified at our article Ball lightning which shows a short movie clip of "Ball lightning seen here following a car" which is quite obviously a reflection of the sun on a wet road that appears to be chasing the car because the camera is in a moving helicopter. If they were indeed real (and I'd put the probability down at one in a hundred that they are) then if they are (as claimed) electrical in nature - then magnetic fields ought to affect them...but as I said...they are about as real as UFO's aren't. SteveBaker (talk) 19:03, 6 December 2007 (UTC)

The article seems to indicate that they are real, and the skeptics are in the minority now. Maybe they just aren't completely understood yet. 64.236.121.129 (talk) 19:10, 6 December 2007 (UTC)

I think there's room for discussion as to what constitutes "real". Are there some phenomena that are real? Absolutely. Is there any one phenomenon that we can identify as "ball lightning" to the exclusion of all others, apart from arbitrarily saying "This is 'ball lightning'"? Perhaps not. If the latter holds, then I think it's fair to say "Ball lightning isn't real", even if there are phenomena that partially resemble descriptions of ball lightning. — Lomn 19:41, 6 December 2007 (UTC)

A load of ball (lightning) or not? [11]--TreeSmiler (talk) 03:13, 7 December 2007 (UTC)

There is a lot of difference between that (which is a ball of burning silicon gas/particles) and ball lightning. Sure, you can get small balls of burning gas under rather special laboratory conditions...nothing too remarkable about that. It's the claims for electrical effects that are dubious. SteveBaker (talk) 16:27, 7 December 2007 (UTC)

I just remembered the name of the phenomenon of burning gas balls that I've been wracking my brain trying to remember since the start of this thread! See Will-o'-the-wisp - little balls of methane that spontaneously ignite after bubbling up from rotting vegetation in marshland. The reason for ignition of the gas is poorly-understood - but once ignited, there is not much mystery. I strongly suspect that something like Bubble fusion is involved - not necessarily actual fusion but a dramatic increase in temperature as bubbles collapse. Since the methane is very unstable in air, it wouldn't take much of a spark to set it off. But it's still not ball lightning - just a more reasonable phenomenon that might explain many of the supposed sightings. SteveBaker (talk) 16:47, 7 December 2007 (UTC)

Ah, and that's where we differ. I'd say it is ball lightning, since that is the term used to describe it. That this term includes the word 'lightning' which implies it has a lot in common with normal lightning is just an historical accident, revealing what people used to think they were. After all, we can talk about Will-o'-the-wisps being 'real' without implying there's any 'will' behind them or that there are little people with lamps guiding travellers to their doom. It's the old thing of not discarding data points that don't fit, but also not necessarily buying the explanations people offer for them. If a lot of people report seeing ball lightning which appears to respond to electrical fields, then that needs to be noted. It might be that it's all an illusion, in which case learning that is good. It might be that it's something else, in which case you've avoided throwing knowledge away. After all, rains of fish were once dismissed as fanciful. Skittle (talk) 18:39, 7 December 2007 (UTC)

Can palms grow in Switzerland and the UK?

Cabbage trees (aka "Torbay Palms") growing in Torquay, England

Hi! I once read that palms can naturally occur in the southernmost parts of Switzerland and in south of England. Is that true? --escondites 18:37, 6 December 2007 (UTC)

From the article Arecaceae (you can find the link in Palm): "The northernmost palm is Chamaerops humilis, which reaches 44°N latitude in southern France, where the local Mediterranean climate is milder than other places as far north." -- kainaw™ 18:48, 6 December 2007 (UTC)

Well, yes...and no. So-called "Cabbage trees" are reasonably cold-tolerant and can be grown in the south-west of England in places with an especially good microclimate such as Torquay. They look an awful lot like palm trees and are sometimes called "Torbay Palms" (although technically, they are not palms at all). Switzerland is considerably further south - so in low-lying areas, it ought to be possible to grow them there too. I don't think true, honest-to-goodness palms do actually grow in England though - but I can't speak for Switzerland. SteveBaker (talk) 18:56, 6 December 2007 (UTC)

Here (http://www.thepalmcentre.co.uk/palms.htm) suggests yes some forms of palm can. Is true ny156uk (talk) 22:44, 6 December 2007 (UTC)

Trachycarpus fortunei has been cultivated in gardens and parks of the Swiss canton of Ticino for hundreds of years - the ones skirting the promenade along the Lago Maggiore, for example, belong to Locarno's touristic trademark. For the past 30 years or so, they have started to grow wild and naturally as an introduced species in the Ticino too. Biologists have studied this trend and linked it to climate change. I remember reading about it in Swiss papers a couple of years ago. International press centre biodiversity research has some information in English. ---Sluzzelin talk 00:50, 7 December 2007 (UTC)

Palms do grow in parts of Cornwall. Bananas can be grown there too, and indeed were in the war. DuncanHill (talk) 00:55, 7 December 2007 (UTC)

Trebah has palms, see [12] for some pics and binomials. DuncanHill (talk) 00:57, 7 December 2007 (UTC)

But can they grow "naturally", i.e. in competition with native species, in southern England? ---Sluzzelin talk 01:03, 7 December 2007 (UTC)

England I dunno, Cornwall I'd say yes, in some places. DuncanHill (talk) 01:06, 7 December 2007 (UTC)

Please forgive me, I meant Great Britain. ---Sluzzelin talk 01:10, 7 December 2007 (UTC)

You are forgiven (on production of one saffron cake), tho' I'm still not happy with your spelling preferences in -ise/-ize :)DuncanHill (talk) 01:20, 7 December 2007 (UTC)

Uh, what are you guys apologizing and forgiving about? Cornwall is in southern England, which is part of England, which is part of Great Britain. --Anon, 01:27 UTC, December 7, 2007.

There's a bit of a 'Free Cornwall' movement. Maybe we should just all split into subcountries and see how that improves things... Free Cotswolds! 79.69.14.132 (talk) 02:08, 7 December 2007 (UTC)

Scilly Isles Also Scotland [13]

—Preceding unsigned comment added by TreeSmiler (talk • contribs) 02:26, 7 December 2007 (UTC)

What's the largest supermassive black hole that we know of?

^Topic 64.236.121.129 (talk) 18:57, 6 December 2007 (UTC)

http://www.google.com/search?q=largest+black+hole suggests the core of galaxy M87, at 3 billion solar masses. — Lomn 19:49, 6 December 2007 (UTC)

Hmm, that's not the largest. Q0906+6930 is larger at 16 billion solar masses, but I don't think it's the largest we know of. 64.236.121.129 (talk) 20:54, 6 December 2007 (UTC)

Mosquitoes the size of birds

Most places with significant numbers of mosquitoes also have tall tales of the exploits of their extra-large mosquitoes -- carrying off small dogs, biting people through the walls of houses, and the like. Which area really has the world's largest mosquitoes? --67.185.172.158 (talk) 19:50, 6 December 2007 (UTC)

A number of references cite mosquitoes of the Toxorhynchites genus as the largest mosquitoes. Toxorhynchites larvae are known to feed on the larvae of other mosquito species. The adults are gentle and peace-loving (well, for mosquitoes)—they don't suck blood, but rather live on plant nectar. I don't know what the full range of all Toxorhynchites species might be – our article lists at least forty or fifty species – but Toxorhynchites rajah comes from East Malaysia. This page has pictures of this mosquito in various stages of development. TenOfAllTrades(talk) 20:03, 6 December 2007 (UTC)

Ah—the Walter Reed Biosystems Unit indicates that the genus Toxorhynchites is very widespread: [14]. (There's also a great picture there—note the bent proboscis and long legs.) —Preceding unsigned comment added by TenOfAllTrades (talk • contribs) 20:12, 6 December 2007 (UTC)

Isn't the daddy long legs (UK edition) technically a mosquito? It's certainly fairly large for an insect and I know that some people are terrified of them. Makes a fairly loud (for an insect) thudding noise when it collides with windows and walls too. --Kurt Shaped Box (talk) 22:50, 6 December 2007 (UTC)

You can hear stag beetles flying towards you in the dusk before you can see them. I guess they would make a fair noise hitting glass. Lanfear's Bane | t 23:41, 6 December 2007 (UTC)

A friend of mine discovered that with the (very large) cockroaches in North Africa, much to his terror one night. English 'roaches just skitter around, you see... --Kurt Shaped Box (talk) 19:20, 7 December 2007 (UTC)

I don't think so. The article includes the phrase Unlike mosquitoes..., and lists mosquito eater as one of their alternative names. Skittle (talk) 00:21, 7 December 2007 (UTC)

Hmmm. Yes, you are correct. Same order, not the same family. Sorry about that. --Kurt Shaped Box (talk) 19:20, 7 December 2007 (UTC)

The so-called "Hexham Grey" seems to be in the running if we're talking about mozzies (Ozzies call them "mozzies", it seems) that bite people. --Milkbreath (talk) 20:03, 7 December 2007 (UTC)

worlds largest mosquitoes? Politicians.

Mammal lips

What is the purpose of the split in the top lips of many mammals? —Preceding unsigned comment added by 84.66.155.90 (talk) 20:46, 6 December 2007 (UTC)

There is cartilage there that allows muscles to have good control of the upper lip. It is called the philtrum. -- kainaw™ 21:26, 6 December 2007 (UTC)

Presumably it is so there is enough skin to stretch when you perform certain mouth movements? Like all the lines in your hand that just seem (to me at least) to be crease-lines because you don't always have your hands in such a way that maximises the amount of surface-area the skin needs to cover. I'm sure someone will confirm this is just gibberish if indeed it is. ny156uk (talk) 22:43, 6 December 2007 (UTC)

The heart

I was reading my bodybuilding magazine and I read that aerobic exercise strengthens the heart and makes the left ventricle thicker, I had previously thought that they said steroids was bad because steroids do that also, so is it really that bad? —Preceding unsigned comment added by 76.167.132.90 (talk) 23:56, 6 December 2007 (UTC)

We actually have a short article just on this (Left ventricular hypertrophy). Muscles naturally enlarge when they strengthen (see Muscle hypertrophy). Anabolic steroids, which are taken illicitly to this effect, are dangerous for their other influences on the human body (see Anabolic steroids#Adverse effects). Someguy1221 (talk) 00:18, 7 December 2007 (UTC)

Actually, I take that partially back. Our own articles disagree over whether LVH is a "bad thing." I'll be researching it now...Someguy1221 (talk) 00:30, 7 December 2007 (UTC)

Ok, I think I have it now. This paper shows that steroid-free exercise-induced LVH is accompanied by a clear increase in cardiac performance, one that is not seen in LVH caused by hypertension (the only alternate cause of LVH discussed in that article). Further, this paper indicates that LVH caused by steroid use is accompanied by decreases in certain aspects of cardiac performance. So LVH itself is not inherently good or bad, as our LVH article suggests, but the impact of LVH plus other, possibly unidentified changes in the heart, is very dependent on the cause of LVH. I hope this answers your question. Someguy1221 (talk) 00:44, 7 December 2007 (UTC)

One (somewhat comic) side-effect of exercise-induced LVH is that it causes you to have a different cardiac rhythm to normal people, which makes jittery paramedics fear something very nasty has happened to your heart. It's not unheard of for marathon runners (who encounter a paramedic for minor stuff like treating cuts and abrasions from a fall) to be whisked off to a cardiac care unit, while loudly protesting that they feel fine and really would rather carry on with the race. -- Finlay McWalter | Talk 01:01, 7 December 2007 (UTC)

I believe the 'nasty side effects' being referred to are hypertension, cardiovascular disease, coronary artery disease and the most horrific of all for our male counterparts, testicular atrophy, the latter of which you would usually not encounter in someone who had achieved left ventricular hypertrophy via aerobic exercise. Cyclonenim (talk) 00:23, 31 December 2007 (UTC)

December 7

Need to burp!

I wonder if this counts as a medical question. Whenever I have a stomach full of gas, I have a hard time burping it out, so it ends up being very uncomfortable and painful until it finally happens.

What are best ways to stimulate burping? — Kieff | Talk 00:57, 7 December 2007 (UTC)

With babies you pat them on the back for a while, maybe it can have the same effect on you? —Preceding unsigned comment added by 128.101.53.177 (talk) 01:08, 7 December 2007 (UTC)

Eno's Fruit Salts. DuncanHill (talk) 01:25, 7 December 2007 (UTC)

Yes it does. This could actually be a medical condition (a feind of mine had similar condition). Please see a doctor.--TreeSmiler (talk) 03:17, 7 December 2007 (UTC)

As far as my understanding of our policies is concerned: a) we can tell you how to induce burping, but b) we can't tell you if it's healthy to do so in your case. If this (epigastric discomfort) is a problem for you, you should see a physician or other health care worker, as it may be a sign of a serious condition (or it could just be gas, but since it's causing you grief, why not look into a solution with a doctor that will stop the gas from forming, rather than finding ways of relieving it?) (EhJJ) 04:15, 7 December 2007 (UTC)

Just as with the question "How do you get to Carnegie Hall?", the answer is "Practice!". Drink something highly carbonated such as seltzer. Learn to relax the muscles in your throat and contract the muscles in your abdomen. Seriously. You can train yourself. People who have had their larynx surgically removed learn to swallow air and burp it out to simulate the buzzing of their now-missing vocal cords; you can probably Google up more info regarding how they train themselves. And then there's the contest in Revenge of the Nerds...

Atlant (talk) 14:08, 7 December 2007 (UTC)

Dear Reference Desk: Does telling someone how to make it worse count as medical advice? I'm uncertain. SteveBaker (talk) 16:16, 7 December 2007 (UTC)

Questioner: Remove the opening sentences and just leave your question. "What are best ways to stimulate burping?" is in no way a request for medical advice. Adding personal history confuses some people and makes it difficult for them to see the question. As with any abnormality, you should seek professional medical advice to ensure that you are healthy. Answering the question - as with babies, patting someone on the back and rubbing the center of the back in circles helps with burping. -- kainaw™ 17:28, 7 December 2007 (UTC)

Wikipedia talk:Reference desk

Hydrogen Peroxide

Does anyone know what the heck is that white gunk you get from hydrogen peroxide you put on any unsterile surface (i.e. sink, tub, bathroom floor), or on raw meat? --Agester (talk) 01:19, 7 December 2007 (UTC)

Beyond "white", tell us something about this "gunk". Is it a solid, liquid? Does it dissolve if you pour some water on it? Does it disappear after sitting for a while? Is it foamy (H₂O₂ decomposes to H₂O and O₂ and this reaction is strongly catalyzed by several common biological materials). DMacks (talk) 02:41, 7 December 2007 (UTC)

It sounds like bleached scum. Graeme Bartlett (talk) 21:22, 7 December 2007 (UTC)

Not quite too sure what it is. But it seems very similar to the foamy stuff if you put hydrogen peroxide in a open cut / wound. I figured it might be the dead bacteria, because when i put it in a clean bowl that i just washed it doesn't build up that foamy stuff, but if i accidentally drip some in my sink it'll foam up similar to it being applied to a cut. And if it isn't assumed I'm talking about the hydrogen peroxide you can get in your local pharmacy for antiseptic uses. --Agester (talk) 01:09, 8 December 2007 (UTC)

The hydrogen peroxide article mentions that the human body, most animals and nearly all aerobic bacteria use catalase, which is an enzyme that speeds the reaction 2H₂0₂-->2H₂0+0₂. I assume you use your sink (bathroom one) to brush your teeth and your tub to wash, right? And there's always bacteria there just growing on the water left over and any biological material. So all this bio-matter in those places has catalase, which decomposes the hydrogen peroxide, which gets caught up in any sort of proteinaceous stuff on the surfaces, creating a foam. Same on the meat---it's like the frothing when it is poured on an open wound.Aquaman590 (talk) 00:38, 9 December 2007 (UTC)

Malt liquor

Is malt liquor sweet? Heegoop, 7 December 2007 (UTC)

Our article on malt liquor doesn't really answer the question, aside from mentioning that sugar is sometimes added. I would guess that it would depend on the particular brew, as it is essentially beer with a little more alcohol (like they sell in Canada and Europe). As a scientist, I'd like to suggest a simple experiment :P (EhJJ) 04:20, 7 December 2007 (UTC)

The article says sugar is sometimes added before fermentation, "to boost the beverage's alcoholic strength". Adding sugar before fermentation has somewhat the opposite effect to adding it afterward, because the yeast use up all the sugar present and turn it into alcohol. —Keenan Pepper 06:17, 7 December 2007 (UTC)

Malt liquor is really little other than distilled beer, and as a brewer I can tell you that beer can be made sweet or not so. Depending on mash temperatures (the temperatures at which the malt is steeped), sugars in the grain are broken down to various degrees. At some temperatures you end up with much of the sugar of the kind yeast likes, and little of the stuff yeast can't easily digest; and at other temperatures, the opposite. Any sugars the yeast doesn't digest to ethanol+CO₂ increase the sweetness of the finished product. Psud (talk) 10:09, 7 December 2007 (UTC)

What?!? Maybe this is a difference in terminology between different places, but around here, what we call "malt liquor" is beer that's a bit stronger than typical beers. It is most emphatically not distilled! It's still just beer. The article Malt liquor also does not mention distillation. If it's distilled, it's not beer. Friday (talk) 16:38, 7 December 2007 (UTC)

Ooops. Brain not switched on (never is at 10:00Z). The stuff I was talking about is properly called "Whiskey". Oh well. We call malt liquor "barley wine" here. Being beer, nothing more, nothing less, it can be naturally somewhat sweet, or its sweetness can be increased by adding lactose (which sacromyces cerviseaSaccharomyces cerevisiae can't digest) or an artificial sweetner. It's all up to the brewer. ----Psud (talk) 13:09, 8 December 2007 (UTC)

As with anything that's brewed, the amount of sugar left at the end of fermentation depends on how much you put in at the outset and how long the fermentation went on. Fermentation stops when either the yeast runs out of sugar to convert - or it poisons itself with it's own alcohol production (or maybe if someone stops it prematurely by messing up the temperature or something). So there are a range of possible outcomes here. Obviously, the manufacturers can also alter the final sweetness by adding more sugar after fermentation is complete. So it's not true to say that because something sweet went in at the outset, that the result will be sweet...but "it depends". SteveBaker (talk) 16:11, 7 December 2007 (UTC)

How much sugar went in; how long it fermented for; and how fermentable the sugars are:

• Starting with unfermentable sugars makes the result sweeter
• Adding unfermentable sugars after fermentation makes the result sweeter
• Killing or filtering the yeast then adding fermentable sugars after fermentation makes the result sweeter
• Adding artificial sweeteners makes the result sweeter
• Stopping fermentation early is wrong and bad and only suitable for childrens' drinks, but does make for a sweeter, lower alcohol drink

--Psud (talk) 13:23, 8 December 2007 (UTC)

• You might be thinking of Malt beverage, which is a little different from malt liquor. In the United States, makers of Alcopops such as Mike's Hard, Zima, etc. refer to the drinks as "flavored malt beverage" or "premium malt beverage". These drinks are very different from malt liquors, which more often taste like smooth beers, as Steel Reserve and Hurricane High Gravity Lager do. Also, don't forget Low-end fortified wine like Mad Dog and Thunderbird -- these are often sold in the same section as the malt liquor, and most of them are very sweet to cut the harsh taste. --M@rēino 19:01, 7 December 2007 (UTC)

Gene transfer a mutation?

Would horizontal gene transfer be considered a mutation for the organism that receives the transferred gene? I'm confused. I stumbled across a PNAS article which seemed to refer to it as a "mutational process," [15] but sometimes the two terms may be observed contrasting with eachother (e.g., [16] , scroll down to the section that says "evolutionary genetics in bacteria"). Thanks! Schmitty120 (talk) 01:33, 7 December 2007 (UTC)

One could argue the semantics of describing the effect of horizontal gene transfer as a mutation. From a strictly technical point of view, it could be considered mutational. For instance, if the gene integrated into the recipient genome it would result in a "mutation" of the genetic insertion site. Likewise, of you wish to use the term to describe the phenotype affected then the recepient could be described as having a "mutant phenotype" and it follows that must have occured by a mutational process. In the link where you suggest it is used in a contrasting manner, I think the use of the term "mutational process" is really a shorthand for "classical mutational processes in vertical gene transfer" (meaning indels and point mutations) in contrast to horizontal gene transfer and recombination. I don't think in calling them "mutations" (or not) the author is attempting to make a point about whether they are involved in the evolutionary process (or not). It is fairly well established that both types of genetic changes have driven evolution (at least in bacteria, see Horizontal gene transfer#Evolutionary theory). Rockpocket 08:15, 7 December 2007 (UTC)

Neurobiology: Effects of decreased membrane capacitance

My script says that Myelination reduces the leakage current and decreases the axon's membrane capacitance. By this the speed of signal propagation is increased. However, I do not see which effect decreasing the membrane capacitance has on the speed of signal propagation in addition to reducing the leakage current. Can somebody please explain this to me? Falk (talk) 08:27, 7 December 2007 (UTC)

We are propagating a potential difference up the axon. By $Q=CV$, we see that for this potential to stay constant, there must be a buildup of charge difference on each side of the membrane, and to get this charge difference there must be an ion flow toward the membrane, which takes time. By reducing capacitance, the necessary charge difference becomes lower. Otherwise, we could say $I=CdV/dt$, in which case reducing the capacitance for a given ion current (the rate of flow of ions we'll assume is constant) increases our voltage propagation speed $dV/dt$. SamuelRiv (talk) 13:27, 7 December 2007 (UTC)

Cold Car Experiment

Two identical cars are started, and their heaters turned on, on a cold wintry morning. One car is encased in half an inch of ice; the other car was covered and is clean. In which car will the internal air temperature rise faster? We've come up with several hypotheses:

a) The icy car will warm faster, because it is insulated with an extra layer of ice.

b) The clean car will warm faster, because the ice on the icy car conducts heat away from the windows faster than air could, due to ice's higher thermal conductivity.

c) It depends on how close the ice is to the freezing/melting point, since

d) It depends on the air temperature or velocity outside -- if the air is significantly colder than the freezing point of water, it will cool the windows faster than melting water.

e) More than one of the above are true, and the problem is too complex to definitively answer.

Your thoughts? jeffjon (talk) 14:07, 7 December 2007 (UTC)

Assuming the outside air temperature is the same as the temperature of the ice (which is reasonable) and that it's a lot colder than zero centigrade (ie well below freezing): I think the one covered in ice will win - ice is a reasonably good insulator - but not as good as air. However, with air, as soon as you heat it up just a bit, it drifts upwards to be replaced with new, cold air. Hence any heat that leaks out of the second car is lost immediately. With first car, with an icy jacket, the heat you radiate goes into warming up the ice - at least until it reaches it's melting point - and that warmth is retained close to the surface of the car. Since the rate of heat loss is proportional to the square of the temperature difference (Newtons law of cooling), the ice-encased car will do better.

If the air around the second car was retained close to the car though (eg if it had a loose car-cover thrown over it) then the superior insulation value of air would win out.

SteveBaker (talk) 15:55, 7 December 2007 (UTC)

I agree with Steve. There would be several minutes of ambient temperature air coming out of the vents until the engine warmed up, then the ice-encased car would have less heat loss due to convection, leading to a faster rise from the assumed below zero C interior temp and temp of the ice. Of course if it were warm outside, then the ice-free car would warm up faster. Edison (talk) 23:55, 7 December 2007 (UTC)

Not so fast. If one car is literally encased in half an inch of ice, then you can't get in to start it at all. It will just sit there cold while the other warms up! :-P More seriously... should any thought be given to the blanket of ice essentially acting as a heat sink - for the engine if nothing else? I agree with the theory that the ice will act as an insulator, but the interior of most cars is composed of cloth, plastics, and foams - surely that degree of internal insulation would minimize any difference to heat loss caused by the ice? Matt Deres (talk) 15:52, 8 December 2007 (UTC)

You can't refer to the car's own insulation, as it's the same between the two cars, and insulationA + insulationB is better than insulationA + nothing. --Psud (talk) 16:54, 8 December 2007 (UTC)

I understand that (I think). I'm just saying that the effect of insulation B isn't going to be much compared to the effect of insulation A and in fact might be completely overshadowed by the heat sink effect. Just a guess on my part, though; I assume Steve is probably correct. Matt Deres (talk) 22:02, 8 December 2007 (UTC)

Let us not forget that if the car were encased in ice, the HVAC air intake would be blocked. The heater core itself would warm up faster because there'd be no airflow through it, but the cabin temperature would not, for the same reason.--Scheinwerfermann (talk) 16:30, 8 December 2007 (UTC)

This sounds like a question for Mythbusters.  :-D -- HiEv 06:11, 9 December 2007 (UTC)

Hovercar?

Think these would ever be viable? How would one break or slow down in one? 64.236.121.129 (talk) 14:19, 7 December 2007 (UTC)

Presumably by reversing the means of propulsion (a fan or whatever). If you can figure out how to make it go forward, you can figure out how to make it slow down. And I would think they would break the same way regular cars do—when it's least convenient, and at great expense. -- Coneslayer (talk) 14:23, 7 December 2007 (UTC)

I reckon they'd be too expensive in fuel. Hovering is very energy intensive, especially when compared to rolling. As to braking, consider an already existing vehicle that can hover - the helicopter. Helicopters brake by vectoring their thrust forward, a hover car would presumably do the same. --Psud (talk) 14:39, 7 December 2007 (UTC)

I think by the time the technology is good enough and reliable enough and they are cheap enough to be somewhat popular, there will be other, far better forms of transportation people will use instead. Recury (talk) 14:41, 7 December 2007 (UTC)

Actually, I like the idea of travel by rocket - a short high acceleration burn; a ballistic arc; a short high acceleration burn to stop. Fun and quick whether across town or across continents! --Psud (talk) 14:45, 7 December 2007 (UTC)

Hovering as in hovercraft? The trouble with hovercraft is that they are very unmanouverable - you don't have friction with the ground - hence you have no brakes. Redirecting thrust to slow you down means that you can't slow down any faster than you can accellerate and if there is even the slightest deviation from aiming the thrust dead straight, there is a tendency for the craft to spin or slip sideways. Stopping at traffic signals would be tough. Energy-efficiency-wise, they aren't so good either. The lack of friction with the ground is a net win - but it's very expensive to maintain the hover thrust - so you end up needing more power than with a car. It's nice to be able to travel over water and to not need paved roads (it would be nice if all of our roads could be turned into lawns - or farmed for grain!). Hovercraft are impractical for other reasons: If your lift motor fails, you can't push the vehicle off the road - if your thrust motor (which is also doing the braking remember!) fails then you have a dangerously uncontrolled vehicle on the streets. At stop lights, or in heavy traffic, everyone has to land and lift off again because, again, there is no way to keep a hovercraft stationary. Even the slightest breeze would be enough to blow you onto the sidewalk if you continued to hover.

Using propellors to direct thrust has another set of problems in that the 'blow back' from the rear of the craft will tend to knock pedestrians off their feet and blow out windows! Also, if two or more hovercraft are manouvering close together (again, think busy city streets with people turning, parking, stopping and starting) - then there are lots of dangerous cross-winds induced by one craft turning that would tend to blow other craft sideways.

All in all, hovercraft just aren't really practical in tight areas. Great for lakes and open grassland and such though. SteveBaker (talk) 15:43, 7 December 2007 (UTC)

• my hovercraft is full of eels --M@rēino 19:07, 7 December 2007 (UTC)

You can buy a hovercar today: the M200G Volantor or the Moller Skycar M400. Rockpocket 19:19, 7 December 2007 (UTC)

That's not really true. They are offered to sell one of their prototypes - on the condition that you basically use it as a museum piece and promise not to fly it - but the price was so high, I don't think they actually managed to find a buyer. You can't actually buy a working, flyable, usable flying/hovering car from them - it's always "a few years away"...which is why Moller are being dragged through the courts over it by their investors. SteveBaker (talk) 19:48, 7 December 2007 (UTC)

Also those are flying cars. That's a bit different. A hovercar doesn't lift off the ground by too much, while a flying car can fly very high. 64.236.121.129 (talk) 19:57, 7 December 2007 (UTC)

"The computer system also prevents the machine from flying higher than 10 feet (3 m) above the ground." - sounds like a hover car to me. I didn't say you should buy one, just that could could buy either of those functional prototypes if you had enough money. It would then be up to you to find somewhere to use it legally. ;) Rockpocket 01:14, 8 December 2007 (UTC)

No, no, no! You can't buy a flying/hovering car that you can actually use - at least not from Moller. The company only ever had ONE flying/hovering car for sale - it was their first prototype - and nobody bought it. BUT you had to sign some kind of legal document promising that you would only use it for display purposes and NEVER attempt to fly it. So if you had a HECK of alot of money (it was in the millions of dollars), you could own a car that was theoretically capable of flying/hovering - but you couldn't actually use it. Check the Moller FAQ if you don't believe me. SteveBaker (talk) 03:33, 8 December 2007 (UTC)

Yes, yes, yes! I can't find anything in the FAQ that says you would be legally restricted from attempting to use it, could you elaborate? This suggests the auction was for a car that is "suitable for test and evaluation only." That sounds like you could happily attempt to "hover" your $3.5M "car" under the guise of an evaluation/test, as long as the local air authorities could be convinced to permit it. Rockpocket 21:39, 8 December 2007 (UTC)

Chemical(s) responsible for Pine/Christmas Tree Scent

Can anybody inform me of the name(s) of the chemical(s) responsible for the fragrance associated with Christmas/Pine trees? --Mark PEA (talk) 16:00, 7 December 2007 (UTC)

I presume pine oil. Someguy1221 (talk) 17:54, 7 December 2007 (UTC)

Most fragrances are very complex mixtures of chemicals - I doubt there is one particular one that produces the "Pine tree" smell. SteveBaker (talk) 19:44, 7 December 2007 (UTC)

Okay, thanks for the answers. I thought maybe there would be some research into the constiuents of pine oil but I can't seem to find any without digging deep. --Mark PEA (talk) 23:51, 7 December 2007 (UTC)

There is certainly scientific literature on this because I have seen it. I think that many of the priciple aroma compounds are monoterpenes such as pinene. ike9898 (talk) 13:12, 8 December 2007 (UTC)

Indeed, the igredients have been identified. [17]. 57% alpha-pinene, 8% beta-pinene, 26% carene, 6% limonene and 3% other hydrocarbons. I don't know if the article identifies the other hydrocarbons, as the only online version I could find was here, and I don't have a subscription to that service. Someguy1221 (talk) 22:38, 8 December 2007 (UTC)

Testosterone Question

I read something about testosterone and how bodybuilders have to keep using more and more each time they use it to get the same effect. Does that mean, that when your off of synthetic testosterone, the testosterone that is body makes is less effective then it used to be before you started using synthetic testosterone? (assuming your body is making the same amount of testosterone as it did before you started using synthetic testosterone) —Preceding unsigned comment added by 71.106.34.15 (talk) 17:18, 7 December 2007 (UTC)

This is a phenomenon known as downregulation, which occurs when any receptor is overstimulated by a ligand. I've never answered a question here before, so maybe someone else can put more effort into it and explain it better. See also: Desensitization (medicine), Drug tolerance, Physical dependence. --Mark PEA (talk) 23:49, 7 December 2007 (UTC)

With testosterone it's more complex than mere downregulation. In fact, when you massively flood your system with artificial testosterone, your endogenous production is completely knocked out. This is what causes rather extreme withdrawl symtoms for several weeks after going cold turkey from steroids, as your body takes that long to regain normal production levels. Additionally, your body will initiate processes to convert excess testosterone into other hormones, including estrogen (if I recall correctly). I'm not sure if these two processes in combination are the complete reason for any apparent drug resistance seen in steroid abusers. Someguy1221 (talk) 23:57, 7 December 2007 (UTC)

Just a little correction, most people dont know this, especially the media and the people that give steroids a bad rep. Educated steroid users (not the little 17 year old kids, im talking about the people that do research and are parts of different steroid or bodybuilding forums), take drugs such as clomid,nolvadex, etc.. or shoot some HGC to restore natural testosterone production, they dont go cold turkey. If they were dumb enough to not use these drugs to restore natural testosterone fuction, they would lose most the muscle they gained and be depressed, and thats not the case with educated users. —Preceding unsigned comment added by 76.167.132.90 (talk) 03:13, 9 December 2007 (UTC)

Autothermal Reforming and Modelling Software

Okay, this is possibly a little specialised but I'm losing track of what reasonable values are for things and nobody else around me seems to be doing better with the software. I'm modelling autothermal reforming of methane with oxygen and steam using PRO/II (pro2), which has to be the most irritating piece of software ever coded. Putting 16152.7060 kmol/hr of my reactants into a Gibbs reactor, at some temperatures the reactor is giving out 3,000 million kJ/hr in heat. At some lower temperatures it requires nearly 300 million kJ/hr heat to be put in. Now, pro2 being as erratic as it is (and given the weird way the duty is varying with the pressure), I'm suspicious of these values. Are they, in fact, reasonable?

Thanks for any help. I've just reached the stage where I'm so frustrated with the software I can't think clearly about the actual process. Skittle (talk) 17:31, 7 December 2007 (UTC)

I really have no knowledge whatsoever of your problem domain. So I'll respond anyway (that's what teh Intarweb is for!). 3,000 million kJ/hr is 833 megawatts, which is pretty close to the electrical output of Three Mile Island's remaining nuclear reactor. Do you anticipate that what you're trying to do should have energetics on the same scale as a power plant? -- Coneslayer (talk) 17:44, 7 December 2007 (UTC)

Hmm, thanks. I wasn't really expecting to get nuclear power plant levels of heat :) Although, it would provide excellent heat integration opportunities. That was the sort of reality check I needed; I was starting to doubt the size of a kilojoule. So, pro2 screws up again. Hooray! Skittle (talk) 18:05, 7 December 2007 (UTC)

BTW, Google is good for quick unit conversions... 3000 million kJ/hour in watts is what I used. -- Coneslayer (talk) 18:29, 7 December 2007 (UTC)

Yes, but without someone who isn't me to tell me 'that's like a power plant', I couldn't be sure I wasn't just being stupid :) Skittle (talk) 18:31, 7 December 2007 (UTC)

We all came from the sun?

Would it be a fair statement to say that we all came from the sun? The matter in our bodies came from the sun, and the energy that sustains us also came from the sun in one form or another. 64.236.121.129 (talk) 19:37, 7 December 2007 (UTC)

That assumes (incorrectly in my opinion) that absolutely no matter from outside the solar system or matter that existed in the ooze that became the solar system made it to Earth. -- kainaw™ 19:44, 7 December 2007 (UTC)

That's true, but how much matter from outside the solar system contributed to the ooze? 64.236.121.129 (talk) 19:47, 7 December 2007 (UTC)

The matter in our bodies did not come from the sun. It came from the Earth (and the stuff on the Earth's surface) and thus (ignoring meteorites and so on as negligable), it came from the cloud of gas and dust that collapsed into the solar system. Some or all (not sure which) of this cloud came from a previous supernova, so we come from a star, but not from the sun in any literal sense. See formation and evolution of the solar system. Algebraist 20:16, 7 December 2007 (UTC)

No, little of you came from the Sun. Much of your body consists of hydrogen (either in the water that comprises much of your body, or in the many compounds that comprise the solid bits), which was formed in the aftermath of the big bang. Almost all of the remaining atoms were made in a sun, but not our Sun. Right now the Sun is turning hydrogen into helium; much later in its life it'll make a few heavier elements. The atoms that comprise your body (bar the aforementioned hydrogen) were made by old suns that have since exploded, the wreckage of which condensed to form the planetary nebula from which the Sun, the Earth, and the rest of our solar system formed. Our Nucleosynthesis article is a good place to start. -- Finlay McWalter | Talk 20:12, 7 December 2007 (UTC)

"Us from the sun"? No way…planets and sun all came from a common origin, not one from the other. See Solar System#Formation. DMacks (talk) 20:14, 7 December 2007 (UTC)

As for the energy that sustains us, virtually all of this comes from the sun. The energy contribution of extra-solar sources is truly negligable in comparison. Some primitive organisms, however, obtain their energy from geothermal sources, which certainly didn't originate from the sun. Someguy1221 (talk) 20:17, 7 December 2007 (UTC)

It would perhaps be better to say that we came from A sun - but not from THE sun. Everything we are made from came from the remnents of one or more dying stars someplace. SteveBaker (talk) 03:35, 8 December 2007 (UTC)

As Carl Sagan puts it "We are made of star stuff". I'd say "some suns" rather than "A sun". And of course, those suns were made of the generation of stars before them, with each generation of stars made of heavier elements than the one before. --Psud (talk) 13:30, 8 December 2007 (UTC)

Gravity fields, mass, volume, density

Lets say we have two objects. Jupiter, and Mini Jupiter. Jupiter, is the planet Jupiter. Both have exactly the same mass. However, Mini Jupiter has a radius of only 500 miles. As such, Mini Jupiter has less volume, but is much more dense. How do their gravity fields compare? Which is stronger? Which is larger? 64.236.121.129 (talk) 19:45, 7 December 2007 (UTC)

You can use simple Newtonian gravity and the shell theorem to figure this out. Outside the radius of Jupiter, the gravitational fields are identical. Inside the radius of Jupiter, Jupiter's own field weakens, its strength now directly proportional to the radius (if you assume Jupiter's density is irrespective of radius, so this is a very very bad assumption. It's assumed for simple physics problems, and I don't know the actual density vs. radius of Jupiter). MiniJupiter's gravity, on the other hand, keeps getting stronger right up until you reach it's edge. Inside of here, it also decreases as you approach the center, under the same bad assumption for density. So MiniJupiter will have stronger gravity inside Jupiter's outer radius, and outside of that radius, they will have equal gravity. Someguy1221 (talk) 19:59, 7 December 2007 (UTC)

Are living beings mostly comprised of water and carbon?

^Topic 64.236.121.129 (talk) 19:49, 7 December 2007 (UTC)

The average organism is said to be about 70% water. In a sense, living organisms are just aqueous chemical reactors. There are some insects that are considerably less that 70% water (as low as 15% if I recall correctly) as an adaptations for dry environments. There are also plants that contain significantly higher than 70% water. As for carbon, well, carbon is a main constituent of every major chemical group in a living organism. Reading from my years old biochemistry notes, living organisms are 1-3% carbohydrates (made mostly of carbon, oxygen, and hydrogen), 2-3% lipids (mostly carbon and hydrogen), 15% protein (mostly carbon, nitrogen, hydrogen, and oxygen), and 7% nucleic acids (mostly carbon, oxygen, nitrogen, hydrogen, and phosphorus). Carbon, oxygen, hydrogen, and nitrogen constitute 96% of living matter (I believe this number is by mass). Someguy1221 (talk) 20:08, 7 December 2007 (UTC)

The Carbon page tells us that that element "is ubiquitous in all known lifeforms, and in the human body it is the second most abundant element by mass (about 18.5%) after oxygen." DMacks (talk) 20:11, 7 December 2007 (UTC)

See also an elemental breakdown at: [18]. Maybe someone who remembers their chemistry class a little better could figure out how much water might be present based on the H & O content. jeffjon (talk) 21:19, 7 December 2007 (UTC)

Large trees have more carbon than water. Inside the tree is dead wood which contains a massive amount fo carbon but no water. David D. (Talk) 23:41, 7 December 2007 (UTC)

I call that cheating. Someguy1221 (talk) 23:54, 7 December 2007 (UTC)

Maybe but lets not let people think that a whole tree is 70% water. David D. (Talk) 03:05, 9 December 2007 (UTC)

Jellyfish are on the other end of the spectrum with up to 98% water. —Preceding unsigned comment added by 84.187.84.147 (talk) 03:52, 8 December 2007 (UTC)

UK telephone extension wiring

I bought a standard UK telephone extension kit (Homebase), wired it up according to the simple instructions, and plugged it into the master socket. (There are no other extensions.) I have two handsets, an old one (maybe ten years old or more) and a new one. Plugging either handset into either socket on its own works just fine: both handsets will ring and give me a dialtone. Plugging the new handset into the master socket and the old one into the extension works just fine too. However, when I set up the configuration I want, with the old one in the master socket and the new one on the extension, the old handset works but the new one is dead. The old handset seems to be somehow blocking the extension. Any ideas how to solve this? Will I have to get another new handset or can the old one be fixed?--Shantavira|^{feed me} 20:10, 7 December 2007 (UTC)

The description you have given of the problem seems to mean that there is a difference between the two sockets. They should be the same. Me, I would double-check my wiring job, with reference to this site and this one. --Milkbreath (talk) 00:12, 8 December 2007 (UTC)

See Ringer equivalence number. This may ring some bells (or not)--TreeSmiler (talk) 01:11, 8 December 2007 (UTC)

REN matters when you have a lot of phones - but it shouldn't be a problem with just two - and it certainly shouldn't matter if you just swap them over. It kinda sounds like a dodgy connection of some kind or another. SteveBaker (talk) 03:39, 8 December 2007 (UTC)

Do you have any6 extra phone wire? Coil it up and connect the old phone to the master through the extension wire. I suspect the ring circuit inside the old phone clamps the ring voltage so that it doesn't get to the extension. Putting more wire between the master socket and the old phone may fix it. --DHeyward (talk) 05:19, 8 December 2007 (UTC)

How many wires did you connect when installing the extension lead: 2,3 or 4?--TreeSmiler (talk) 07:11, 8 December 2007 (UTC)

Four.--Shantavira|^{feed me} 09:59, 8 December 2007 (UTC)

Maternal depressions effects on the Family

What are the effects of maternal depression on the spouse and children, especially teenagers? —Preceding unsigned comment added by 75.131.194.201 (talk) 21:24, 7 December 2007 (UTC)

Wikipedia has postnatal depression. A starting point in the research literature: Do Parenting and the Home Environment, Maternal Depression, Neighborhood, and Chronic Poverty Affect Child Behavioral Problems Differently in Different Racial-Ethnic Groups?
--JWSchmidt (talk) 00:49, 8 December 2007 (UTC)

Photographs

If I point a camera at a brick wall, I see straight lines of bricks running left and right. I really don't understand how this is possible. Since the far corners of the wall are farther away from the camera than the brick directly in front of the camera, they should logically be both out of focus and smaller than the center. I believe our eye corrects for this because it projects the image on a curved surface, but the film in a camera is flat, so this shouldn't affect it. How does this work? 72.155.209.101 (talk) 21:44, 7 December 2007 (UTC)

The focus is due to the depth of focus (dependant on the aperture). In short there can potentially be a wide range of distance that remains in focus. David D. (Talk) 23:38, 7 December 2007 (UTC)

It does get out of focus, if you're shooting with 85mm f/1.2 at 1m away from the wall, or try some macro photography. Point and shoot cameras usually has enough DOF (which is also dependant on the focal length is well) to get pretty much everything in focus. --antilived^{T | C | G} 01:41, 8 December 2007 (UTC)

That's not what I am saying. There is a focal plane, here represented by the wall - DOF does not factor in if the object is flat. Try shooting a grid; if I'm right, the corners squares will be smaller than the center squares and not on the focal "plane" (since they are farther away from the lens). Even if I have your 85mm f/1.2 pointed at this hypothetical wall, the wall would all be in focus, since it is flat. However, the far corners of the wall are farther away from the lens than the part directly in front of the camera. Thus, rather than a focal plane, should we not be seeing a focal sphere, where the points in focus lie at equal distance from the camera? And since the points farther away from the camera are, well, farther away, should they not be rendered smaller? 72.155.209.101 (talk) 02:32, 8 December 2007 (UTC)

(edit conflict) It all depends on the projection. Normal camera lenses are designed to give a rectilinear projection, which has the desirable property that the resulting image looks "right" (as in undistorted) when displayed on a flat surface (such as a piece of paper or a computer screen) — assuming the viewing distance and angle are correct. (Fortunately, our brains also tend to mostly ignore the small distortions that result from viewing such images from a wrong distance or angle, as long as the mismatch isn't too severe.) Essentially, this is because the rectilinear projection is exactly what you'd get if you, say, held up a flat transparent sheet in front of your face and traced the scene onto it as you saw it.

However, the rectilinear projection does have some disadvantages, particularly in wide-angle photography. One is that it can't possibly produce a field of view wider than 180°, and even at much lower fields of view (say, anything over 60°) it tends to look distorted unless projected on a very large canvas and/or viewed from a very close distance. Another problem is that, contrary to what you might expect, if you rotate the camera the image will not simply scroll left or right — rather, horizontal lines will appear to rotate. This is the price one has to pay for keeping straight lines straight, and is related to the effect known as the corner illusion (or I thought it was, but I can't find an article on it — perhaps I'm misremembering the name). There are alternative projections, commonly used in panoramic photography, which avoid this at the cost of making some straight lines appear curved. —Ilmari Karonen (talk) 02:38, 8 December 2007 (UTC)

Molecular solution

From [19], a distinction is made between a solution and a molecular solution. I have never heard of this before, but I am not a chemist. Can anyone clarify this? If this is important, maybe we should have an article on molecular solution ?--Filll (talk) 23:12, 7 December 2007 (UTC)

They seem to be referring to ionic organometallic compounds. Unlike an inorganic salt, these compounds don't fully dissociate in solution, and instead form complexes of several carbanions and metallic ions. However, I've never heard this term used to describe it. Someguy1221 (talk) 23:27, 7 December 2007 (UTC)

December 8

Final cause of death in cancer

I never understood why cancer was so deadly. Yes, you do have an abnormal growth/tumor growing somewhere in your body, but I don't see why that would eventually cause death. If there was a tumor within a blood vessel that directly caused a stroke or heart attack, then the cause of death in that case is quite obvious. But in "normal cancer" (if such a thing exists), what is usually the final cause of death?

I asked myself that same question a year or two ago, and the answer I came up with after a bit of research is nobody really knows. They don't do autopsies on cancer deaths, and the oncology community seems to be concentrating on getting rid of the cancer to the exclusion of finding out exactly how it kills. Some ideas are that the tumor sometimes, of course, impinges on something vital like the pancreas and you die from the trauma to the vital part. Brain tumors are obviously going to kill you by compressing the brain. But the main deadly effect of a tumor seems to be that it disrupts your chemistry. Tumors produce all sorts of nasty chemicals as though they were a gland, which accounts for the weight loss that accompanies them. But nobody as far as I could find out has determined exactly which chemicals do what when. I remember thinking at the time that there might be a way to live with cancer if we could counteract that process, but what do I know? --Milkbreath (talk) 01:54, 8 December 2007 (UTC)

Take a look at metastasis. In many cases, a primary tumor can be surgically removed, but once cancer cells start to spread away from the primary tumor there is a greater chance that the cancer cells will not be stopped by treatment before they disrupt the function of a vital organ. For example, see melanoma and Surgical Excision of Metastatic Malignant Melanoma Involving the Tricuspid Valve.
--JWSchmidt (talk) 02:54, 8 December 2007 (UTC)

A study of 506 terminal cancer patients (J Med. 1975;6(1):61-4) found the cause of death was:

• Infection (36%, and was a contributing factor an an additional 68%)
• hemorrhagic and thromboembolic phenomena (18%, and were contributory factors in an additional 43%)
• Respiratory failure (19%, and a contributory factor in an additional 3%)
• Organ failure after invasion by neoplastic cells (10%, and was a contributing factor an an additional 5%)
• Cardiovascular insufficiency (7%, and a contributory factor in an additional 3%)
• Cachexia (1% and as contributory factor in another 0.4%)

That was done over 35 years ago, so the distribution may have since changed, but it is nevertheless indicative of how tumors disrupt the normal function of our organs by diverting resources away to feed their growth. This results in organ malfunction as the tumor invades, vascular malfunction as blood vessels are grown to feed the tumor and starve the tissues. As the patient loses weight because the tumor takes all their nourishment, they begin to get weaker which leaves the more prone to infection, and the immune system cannot fight infection as well. Rockpocket 03:03, 8 December 2007 (UTC)

Indeed, a more recent study suggests infection is better controlled these days and has been overtaken by the other causes, in J Thromb Haemost. 2007 Mar;5(3):632-4 the authors report: "Of 4,466 patients enrolled on study, 141 (3.2%) patients died during the period of observation ... A majority of patients died of progression of underlying cancer (n=100, 70.9%). Among non-cancer causes of death, thrombosis and infection were the leading contributors (n=13, 9.2% for each). Thromboembolic events contributing to death included myocardial infarction (n=3), stroke (n=2), cardiac arrest (n=2), ischemic bowel (n=1) and VTE (n=5). Infectious events contributing to death included sepsis (n=10), pneumonia (n=2), and bacterial meningitis (n=1). Other causes of death included respiratory failure (n=5), aspiration pneumonitis (n=2) and bleeding complications (n=2). Cause of death was reported as unknown in 5 patients." Rockpocket 03:16, 8 December 2007 (UTC)

Ummm - A study of 506 terminal cancer patients (J Med. 1975;6(1):61-4) found the cause of death was: Infection (36%, and was a contributing factor an an additional 68%). Now, 36% + 68% = 104%. Shome mishtake shurely? DuncanHill (talk) 07:45, 8 December 2007 (UTC)

Maybe they meant 68% of the remaining deaths? I can't find this paper. J Med. Which journal of medicine? Someguy1221 (talk) 08:06, 8 December 2007 (UTC)

Mmmmm. Good point. Perhaps I paraphrased incorrectly and they meant, as Someguy suggests, 68% of the other deaths. The article is PMID 1056415 Rockpocket 21:03, 8 December 2007 (UTC)

How to solve Physics Problem by Using Kinetic Energy Principle?

So, a ball weighing 2.6 kg falls from a state of rest 55 cm. It then lands on a spring that decompresses 15 cm. Assuming the acceleration of gravity is (-)9.8 m/s and that there is no air resistance, what is the k value of the spring?

OK, so according to KE Principle:

Wnet=deltaKE or Wnet=KE'-KE

Since the ball is at rest in the beginning and end, the right side of the equation equals zero:

Wnet=0

We also know that W=Fd

Fnetd=0

So the net forces is that of the spring, which is described as Fs=-kx, and the force of gravity, which is desribed as Fg=mg,

(-kx+mg)d=0

At this point I am kind of unsure what d is supposed to represent, but I guess d=.7 m. m=2.6 kg, x= (-).15 m, g=(-)9.8:

.7(.15k+2.6*-9.8)=0

k=(25.48/.15)~170

By using the Law of Energy Conservation (E=E'), I got a value that was about 10 times this, and I am certain I did that work right.

I also tried:

d1(-kx)+d2(mg)=0, where d1 is the distance over the force of the spring was applied and d2 is the distance over the force of gravity was applied.

(.15*.15k)+(.7*2.6*-9.8)=0

.0225k=17.836

k~790

Closer, but the answer is still twice that.

Any advice would be greatly appreciated. —Preceding unsigned comment added by 24.125.31.205 (talk) 05:31, 8 December 2007 (UTC)

Your first method is not what you're trying to solve: You're working out the force, not the energy. I would just work out the V of the ball when it was at rest, using $V=mgh=2.6\cdot 9.8\cdot 0.7=17.836$. Hooke's law say $U={\frac {1}{2}}kx^{2}$, substituting in the variables you get $17.836={\frac {1}{2}}k\cdot 0.15^{2}$, simple algebra re-arranging gives $k={\frac {17.836\cdot 2}{0.15^{2}}}=1585.42$. You just forgot to multiply the energy stored in the spring by 2 when you're finding k. --antilived^{T | C | G} 09:14, 8 December 2007 (UTC)

Electric Shavers

In TV commercials, those guys just keep shaving every which way but I wanna know if that is really possible. I mean with a regular razor you cant shave against the grain right? So with an electric razor is it possible? If yes, why? And if not, then what are the consequences of shaving against the grain? —Preceding unsigned comment added by 202.83.169.98 (talk) 07:33, 8 December 2007 (UTC)

I shave against the grain. My face is fine...Someguy1221 (talk) 08:07, 8 December 2007 (UTC)

Shaving#Electric shaving. Moving against the grain can help force the hairs into the small holes that give access to the moving blades. --JWSchmidt (talk) 15:01, 8 December 2007 (UTC)

Some say that (blade) shaving against the grain forces the hair beneath the skin and leads to ingrown hairs, but it doesn't bother me (and leads to a much closer shave). —Steve Summit (talk) 17:07, 8 December 2007 (UTC)

I have very heavy, thick whiskers. Although I have a full beard, I shave my neck and upper cheeks every day, and I use a regular two-bladed disposable razor most of the time. If I did NOT shave against the grain, I'd not be able to have a clean shave, but would have uncomfortable stubble left behind. If I use an electric razor I never get as close a shave as a simple cheap Bic disposable razor. I've never discovered the advantage of using an electric razor. Why would I want to buy an expensive razor that requires electricity to run and doesn't shave as close? Saukkomies 19:18, 8 December 2007 (UTC)

Less time/mess? If I had to bother lathering up every morning, I'd probably have a long, droopy moustache in addition to a long, scruffy beard... ;) --Kurt Shaped Box (talk) 19:22, 8 December 2007 (UTC)

Who lathers up? Heh. I never have used any kind of shaving cream or anything like that. I just find that shaving as soon as possible after I shower in the morning that my skin is moist and warm enough from the shower that I do not need to put anything on my skin to prepare to shave. I do make sure to wash the skin that is going to be shaved while in the shower - freshly washed skin helps the razor to work better. But lathering is such a drag! I agree with you Kurt, if I had to lather to shave, I'd give it up altogether. As it is, I spend perhaps 30 seconds on the entire shaving process each morning - and there is no mess to clean up since the whiskers get washed immediately down the drain when I rinse the razor off in the flowing water. Keep in mind that my whiskers are exceptionally thick and dense, and I am also quite prone to razor burn. But I have very positive results from simply shaving right after I shower, not using shaving cream, going against the grain, and using a regular double bladed non-electric razor. Saukkomies 19:34, 8 December 2007 (UTC)

The rotary electric shavers cut in different directions around the circumpherence of each 'pad' anyway - I don't think it matters that much which direction you move the body of the shaver. (But then, I havn't shaved in 10 years...so what do I know?) SteveBaker (talk) 00:02, 9 December 2007 (UTC)

I went electric(al) because I like it. I find it easy, no lathering and no need to buy a cartridge (razor) every fortnight. Non-electric razors are quite expensive here in Argentina. Well, that's my call.

As Steve points out, electric shavers cut in different directions. I'd usually make a series of movements: against the grain, then circular (clock/counterclockwise) moves, etc. Pallida  Mors 23:54, 9 December 2007 (UTC)

Hermaphrodites

What are hermaphrodites? How are they born?--61.2.17.179 (talk) 08:59, 8 December 2007 (UTC)--61.2.17.179 (talk) 08:59, 8 December 2007 (UTC)

Hermaphrodite. If you have a more specific question, feel free to ask it. Someguy1221 (talk) 09:07, 8 December 2007 (UTC)

There happens to be a wonderful article here on human hermaphroditism. (But stay away from the bottom quarter if you don't like yucky things!) Someguy1221 (talk) 09:21, 8 December 2007 (UTC)

I didn't see anything "yucky" there. It was just a description of a different culture's relationship to gender and sex. Not that I'd want to live there, but Western cultures sure don't have it all figured out either! Saudade7 14:51, 8 December 2007 (UTC)

Unknown type of digital or optical distortion

The camera was handheld but in the past whenever I have seen a blur it has included the whole picture. I though digital cameras exposed the whole scene at once rather than scanning the picture maybe like an old TV camera would do. What method of taking the picture and/or what action could cause this type of digital or optical distortion?

Multimillionaire (talk) 11:52, 8 December 2007 (UTC)

Light coming from the bicycle into your camera being refracted due to the difference in density of air in that area. Just a wild guess though, might be wrong :P. Oidia (talk) 11:58, 8 December 2007 (UTC)

Is this the entire photo, or is it the corner of a larger photo? --Psud (talk) 13:45, 8 December 2007 (UTC)

Its the whole photo. Multimillionaire (talk) 22:39, 8 December 2007 (UTC)

The date in the corner suggests it is an entire photo. I'd say you weren't holding the camera/cellular phone still when taking it. The distortion is circular in nature with intensity increasing towards the bottom left hand corner. I'd say you pivoted the camera when shooting. --Ouro (blah blah) 14:08, 8 December 2007 (UTC)

Identify squirrel species

Squirrels of this kind are very common where I live. What species is this? [20] [21] - Sikon (talk) 13:19, 8 December 2007 (UTC)

Where do you live? (That's important). It is some type of tassel-eared squirrel. Not a Kaibab Squirrel squirrel though. Saudade7 14:54, 8 December 2007 (UTC)

Novosibirsk, Russia. - Sikon (talk) 16:32, 8 December 2007 (UTC)

Could be a Eurasian red squirrel. --Milkbreath (talk) 17:35, 8 December 2007 (UTC)

I agree - in winter they have grey fur over their bodies with the red fur remaining over head and paws - that's something you don't see in other squirrels (as far as I know). (The [[Red Squirrel article was the first thing I ever edited on Wikipedia!) SteveBaker (talk) 23:57, 8 December 2007 (UTC)

Blacksmithing messes with my hair

Good morning Wikipedians!

I spent the afternoon yesterday (Saturday) working over a coke fuelled forge. The coke proved excessively hard to light, and so we employed barbecue briquettes to get the fire going. I ended up with a fair bit of ash in my hair, and my hair felt tangled and matted. When I got home, I rinsed (but didn't wash) my hair. But my hair remains tangled feeling, and I'm thinking I probably need to wash it to get it back to something like normal.

Other probably relevant things I noted were:

• There was a bit of sulpher in the fire, evidenced by yellow deposits which formed on the coke and sulpherous smell when I rinsed my hair. I'm pretty sure the sulpher came from the briquettes, as there was no evidence of it once the fire was burning only coke.
• There was a fair bit of sweat in my hair
• A diffuse white flame burned over the fuel in the forge while it was burning briquettes and coke at the same time
• My hair is about 15cm long measured from scalp to tip of a handful of hair
• The forge has no hood over it, so my hair was exposed to radiant heat, but there is no evidence that it was scorched at all.

My first thought was that it was the sweat that turned my hair into a tangled mess, but I expected that to be fixed by a rinse. Any ideas, or suggestions for how to prevent the same in future? --Psud (talk) 15:02, 8 December 2007 (UTC)

We may need a bit more information. Since it sounds like washing (as opposed to rinsing) your hair is a big deal for you, I'm guessing you don't do it every day -- and perhaps you go for long periods without washing your hair. If so, your hair will have a lot more of its natural oils in it than many/most of us are used to. Also, it's possible that you have some unusual (to me) hairdo, such as dreadlocks or a mohawk, perhaps requiring added substances to keep it in place. All of these possibilities increase the number of unusual reactions that could have taken place between your hair and the heat/fumes/ash given off by the forge. —Steve Summit (talk) 16:58, 8 December 2007 (UTC)

Hair washing isn't a big deal, I just didn't have any shampoo handy. Hairstyle is fairly conventional. No "product" to hold it in place. Hair was washed 3 days ago (usually wash it weekly(, but have gone for up to 3 months without washing hair - but that's another story)). --Psud (talk) 17:42, 8 December 2007 (UTC)

Ash is very alkaline and can react with oil in the hair to make soap. Also if you overheated your hair it could be frizzed and weakened, so that it will easily tangle and break. Give the hair a good brushing to remove the broken bits, and dust, and to help untangle it! Graeme Bartlett (talk) 21:41, 8 December 2007 (UTC)

Have you tried a liberal dose of conditioner? Vranak (talk) 22:41, 8 December 2007 (UTC)

I fixed my hair with a washing and far more conditioning than I would normally use. I take it from lack of comments suggesting the possibility that the copious quantities of sweat wasn't the cause. Speaking of sweat, for anyone who hasn't tried it, blacksmithing is an odd thermal experience - ambient air temperature away from the forge was 33°C (~92F), the radiant heat of the forge heated all of me above the top of my leather apron causing me to sweat profusely, all of me below the top of the apron was cooled by the sweat but not particularly heated by the forge, so I felt incredibly hot from the shoulders up, and was shivering below that. --Psud (talk) 11:59, 9 December 2007 (UTC)

Laptops

Which laptop is the best for home usage:

  1) Acer
  2) HP
  3) Compaq
  4) Dell
  5) Sony Vaio 

In terms of specifications{Speed and hard disk capacity} and the regularity of usage..... —Preceding unsigned comment added by Garb wire (talk • contribs) 15:07, 8 December 2007 (UTC)

You could get all different specifications of laptop from those companies. Some Acer laptops are better than some HP laptops and some HP laptops are better than Acer laptops. What exactly is "home usage"? You sound like you'd be fine with one of the cheapest (internet browsing, typing letters). I'm guessing that someone who needed a more powerful computer (image/video editing, first-person shooter players) would not have asked the question you just did. If you confirm what it is you want to do with the machine, someone else will confirm that you only need something cheap. --Seans Potato Business 15:16, 8 December 2007 (UTC)

Apple. But Really, you should ask this on the Wikipedia:Reference desk/Computing page, this one is just for Science. The People on the Computer page are incredibly smart and helpful. Good Luck. Saudade7 15:31, 8 December 2007 (UTC)

And so he did :) --Ouro (blah blah) 20:24, 8 December 2007 (UTC)

Did Saudade7 just call us all stupid and unhelpful? I feel...somehow abused.  :-) SteveBaker (talk) 23:51, 8 December 2007 (UTC)

Tough one. But seeing as some of us also do participate at the Computing RefDesk, I'd say you shouldn't feel too bad ;) --Ouro (blah blah) 06:43, 9 December 2007 (UTC)

Flame from engine exhaust

In the film Grease, you see flames coming from one of the cars two exhausts. What's that all about? --Seans Potato Business 15:12, 8 December 2007 (UTC)

I've heard of hot rodders making modifications specifically for this purpose. I don't remember details, but the gist is that they inject something flammable into the exhaust system near the end, at the flip of a switch. I don't remember if they also need a spark there or if the exhaust ignites it. Alright, here is a link to a commercial vendor of modern kits for this. They explain how their kit works.. Oh, they're fiddling with the engine to pass unburned fuel through rather than injecting new fuel at that point, then they ignite it with a spark. Hmm, not sure how I feel about that. But, it's all only for looks anyway. You will also see naturally produced exhaust flames from cars like dragsters whose only "exhaust system" are a couple feet of headers, which just open right to the air. In that case, they're not doing anything on purpose to produce the flames, but they get them anyway. Friday (talk) 16:59, 8 December 2007 (UTC)

I don't think such a device would be legal in the UK. There are strict regulations regarding emissions. Does that not apply in the US? —Preceding unsigned comment added by Seans Potato Business (talk • contribs) 17:53, 8 December 2007 (UTC)

I imagine it's not legal in many parts. But, not every place in the US does emissions testing. And, if you don't hit the button during the test I imagine you'd have normal emissions. Friday (talk) 17:57, 8 December 2007 (UTC)

As I understand it, testing is done everywhere but the strictness of the test depends on the level of urbanization. The only exemptions I know of are for the poor. It is illegal to modify any emissions control devices. --DHeyward (talk) 19:53, 8 December 2007 (UTC)

These guys: http://www.eatmyflames.com will sell you a kit to do that for around $50. They are of course illegal in most places around the world. They generally require that you remove the catalytic convertor from your exhaust - so it's 100% certain that you aren't going to pass emissions testing even if you don't turn it on during the test. SteveBaker (talk) 23:48, 8 December 2007 (UTC)

Formula One Car Speed

I'm researching the properties of carbon fiber. Could anybody tell me how much force the carbon fiber shell on a Formula One car must withstand? SevenFiveOne (talk) 15:20, 8 December 2007 (UTC)

Here is a document from the FIA that seems to have some info. Sections 3.17 and 16.1 look promising. From what I saw, the shell isn't considered so much part of the impact protection, so the specs for that deal only with deflection caused by the airstream. --Milkbreath (talk) 16:33, 8 December 2007 (UTC)

I the car has good aerodynamics (as it really ought to if it's a Formula 1 car) then there should be very little aero forces on the shell. The strength of the car comes from it's internal metal frame. So I don't think there is much stress on the carbon fibre parts anyway. SteveBaker (talk) 20:22, 8 December 2007 (UTC)

Hydrogen Cars - Potential Future Issue?

understand the only 'output' out of the exhaust for hydrogen cars is water. I was interested whether this might cause a potential problem in the future for high-usage roads like motorways. If there are, say, 10,000 cars an hour going through 1 mile of road all expelling a small amount of water - well would that mean the roads might always be wet/damp thus making braking distances longer? I guess the ouput of one hydrogen car wouldn't be much but with 1000s would it become more of a problem? ny156uk (talk) 16:35, 8 December 2007 (UTC)

Such problems might indeed be a problem, for instance with cold weather, but they will also easily be solved. Think for instance about tyres/asphalt with better water disposal qualities, or simply putting the exhaust on the side or in the middle and building draining facilities at those spots in the roads. - Dammit (talk) 16:43, 8 December 2007 (UTC)

If there is also waste heat, maybe they could use it to evaporate the waste water? No idea if they really do this, just speculating.. Friday (talk) 17:21, 8 December 2007 (UTC)

Of course, the water does come out as vapor. (Indeed, the fact that the water resulting from virtually any combustion reaction comes out as vapor rather than liquid water represents a significant form of waste heat in itself, and accounts for the distinction between HHV and LHV.)

So the first result of large-scale use of hydrogen-fueled cars would be an increase in the humidity immediately surrounding busy motorways. In cold weather, or on a morning following a chilly night when the pavement is still cold, I can easily imagine this resulting in significant condensation on the roadway surface. It would be an interesting back-of-the-envelope calculation (which I am nevertheless not going to undertake just now) to try to quantify this effect. —Steve Summit (talk) 17:48, 8 December 2007 (UTC)

As an aside, water vapor is a greenhouse gas as well. How come this isn't a concern? --DHeyward (talk) 19:55, 8 December 2007 (UTC)

Because the amount of water the atmosphere can hold is a factor of temperature. Once the humidity gets high enough for that temperature, the water just rains back down. It doesn't have the long-term cumulative effects that other greenhouse gasses have. -- HiEv 06:42, 9 December 2007 (UTC)

We should point out that regular gasoline cars generate a lot of water in their exhausts too - perhaps not as much as a hydrogen car - but even so - it's quite a bit. Just watch your car exhaust with the engine running on a cool day and you'll see water dripping out of the end. I really don't think you'd even notice the change over in terms of water production. Water vapour is only a problem as a greenhouse gas if it makes it up into the upper atmosphere. The water vapor from car exhausts is mostly going to wind up like the water that evaporates from rivers, lakes and oceans - forming clouds. Louds do trap sunlight - but they also reflect it away out into space. SteveBaker (talk) 20:19, 8 December 2007 (UTC)

Temperature and Breathing rate

If someone fell into a pool of freezing water and remained there for an hour, would they still survive? And if they did, would temperature somehow be connected to it? Thanks, Valens Impérial Császár 93 17:00, 8 December 2007 (UTC)

They would almost certainly not survive, and of course temperature would have everything to do with it. See hypothermia. —Steve Summit (talk) 17:14, 8 December 2007 (UTC)

There are people who have swum in freezing water - but even with a lot of preparation and vigerously exercising - they can't survive for long. You hear stories of people falling overboard from arctic fishing boats who died from hypothermia in less than two minutes. So evidently a lot depends of preparation - but I don't think it's possible to survive an hour. Your body simply can't generate enough heat to maintain a minimal body temperature with that much loss of heat. SteveBaker (talk) 20:08, 8 December 2007 (UTC)

According to our hypothermia article, there are reports of children being resuscitated after two hours (!!), but those cases are certainly exceptional. (But they're why I said "almost certainly" instead of "certainly".)

Also according to our article, you're "not dead from hypothermia until you're warm and dead". The interesting thing about hypothermia is that it involves (or, depending on how you define things, it is) a natural, biological, hibernative or suspended animation state. But it's very tricky for humans to revive from. There's a story of 16 hale Danish sailors who sometime in the 1980s were rescued alive after bobbing in the North Atlantic for ninety minutes or so after their ship sank out from underneath them. While being fed and warmed in the galley or sick bay of the rescuing vessel, all 16 of them dropped dead. :-( —Steve Summit (talk) 20:57, 8 December 2007 (UTC)

December 9

inverse sqaure law for vortices

for a traveling vortex of air, does the amount of pressure it produces decay occording to inverse square law [half the distance, four times the force] or along another line, if so what amount does the amount of pressure transported by the vortex decay by over distance?

Robin —Preceding unsigned comment added by 80.6.37.199 (talk) 00:03, 9 December 2007 (UTC)

I think this is a rather complicated effect. It's unlikely to be inverse-square because you get those amazing Vortex ring guns - or the more reasonable Air bazooka or Vortex ring toys that propel a stable vortex over large distances with seemingly little energy loss. SteveBaker (talk) 00:22, 9 December 2007 (UTC)

It is a complicated effect, however they do loose momentum over distance, and thus exert less pressure, doews anyone have any idea on the equasion or know the way it works?

Robin —Preceding unsigned comment added by 80.6.37.199 (talk) 00:42, 9 December 2007 (UTC)

Aspherical Lenses

Why are aspherical lenses so much harder to make? than spherical ones What's the optimum lens shape? --antilived^{T | C | G} 09:04, 9 December 2007 (UTC)

lenses with circular symmetry can be roughly made by spinning the glass against a grinder as in a lathe, but aspherical lenses are a more complicated shape! Graeme Bartlett (talk) 11:44, 9 December 2007 (UTC)

There isn't a single 'optimum lens shape' - it depends on the task you wish the lens to perform. For example, if you have one of those 'Laser line level' gadgets (especially one of the cheaper ones) that produces a fan-shaped beam of laser light - inside you'll find a cylindrical lens. On the other hand, most contact lenses are spherical - unless used for treating Astigmatism - in which case a non-spherical lens of some kind will be needed. SteveBaker (talk) 13:16, 9 December 2007 (UTC)

By optimum I mean one that has the least aberration. Spherical lenses has spherical aberration, so how about a parabolic lens, or some other shapes? Also, can't you just make the grinder aspherical is well and you can start grinding aspherical lenses in the exact same fashion? --antilived^{T | C | G} 04:55, 10 December 2007 (UTC)

The point is that there is no shape of lens that is optimal (aberration-free) for all conditions and applications. So, for instance, if you work out the best possible shape of a lens for imaging a person standing 20 metres away onto a camera film, then that lens will not be the best possible shape for imaging someone standing 25 metres away. The amount of spherical aberration isn't a fixed quantity for a given (spherical) lens, it also varies depending on exactly what you are using the lens for.

Lens grinding is a complex topic, but in the traditional method for grinding a spherical lens surface, the glass blank is ground against a tool with a hollow spherical interior surface. It doesn't just rotate around one point (like on a lathe), but moves sideways and rotates at the same time. A pair of exterior and interior spherical surfaces are the only surfaces which fit together like this, where they can touch each other at all points in any orientation and position.

The reason you can't just spin it like a lathe is that you end up scoring circular striations in the glass if it can't move and rotate at the same time. Though some modern aspheric grinding systems can place the cutting tool so accurately that they do work like a lathe, grinding away a tiny bit of the glass at a time. --Bob Mellish (talk) 05:42, 10 December 2007 (UTC)

My Mobile Phone Underwent Strange Situation!

My nokia model 3310 (oldest known version) has now got a strange problem! It's accepting any other sim except my sim! If I'm putting my sim it was saying "simcard rejected"! At the same time it was accepting every other sim i tried in it! Same is the case with my sim card! It was working in all other models like sony errickson, motorola, LG, etc, but it was not accepted in any of the nokia model.."simcard rejected"! What might be the reason? & solution? Temuzion (talk) 09:57, 9 December 2007 (UTC)

Must say I'm stumped! I've been using this model of mobile phone since 2001 and nothing like this has happened to me (although I've got one N3310 acting very weird too). Did you do anything just before you experienced these problems (drop the phone, change the battery, tamper with it in any way, receive any strange/unusual SMS/picture message) or did it just happen suddenly? I like the way you spelled sony errickson ;) Cheers, Ouro (blah blah) 10:36, 9 December 2007 (UTC)

I'd expect it to be a problem with your sim card. I expect it's possible to have a sim card fault that your phone cares about but others don't. I don't know where you are, but in Australia the phone company owns the sim card, so I suggest you go to your mobile service provider and tell them that their sim card is faulty. They should replace it. --Psud (talk) 12:07, 9 December 2007 (UTC)

This happened to me once, and was because I had been swapping simcards with people a lot, as well as removing and reinserting the sim a lot because the phone was glitchy. Basically, the sim got scratched in a way that was specific to my phone, because it was the connectors on my phone that did the scratching. I was never able to get that sim and that phone to work together again, so I think you may have to choose between them and replace the other. Needless to say, I now remove the sim very carefully if it's necessary. Skittle (talk) 13:02, 9 December 2007 (UTC)

If I'm reading you correctly, it sounds like you could have abbreviated your situation as, "No phone accepts my SIM card," in which case the answer seems obvious: there's a problem with your SIM card. Your phone is probably fine, you just need to get your SIM card fixed. -- HiEv 00:01, 10 December 2007 (UTC)

But my sim is active in all other models except nokia range! May be nokia software is rejecting the sim! & one more thing! I just dropped my phone twice in the last month & another thing is thatI took the message offer by which I got 500 free messages to be sent to any mobile & by that offer I m using the sms service extensively! & previously once the problem rose when dealing with sms only! But none of the components can be avoided b'coz both are working but in but in diffrent models..so ultimately what should I do? Temuzion (talk) 03:05, 10 December 2007 (UTC)

If it were me nowadays, I would take my sim to get a backup made at one of the places that does that (Carphone Warehouse? I imagine most phone places do it), then see if the backup works in the phone. This is because I suspect something has physically happened to your sim that is specific to the way it connects with the nokia. Getting a physically different sim would solve this problem. If it still doesn't work, something much odder must have happened. In that case I'd get a new phone, unless you don't mind swapping your number and re-inputting your phonebook and losing the pictures saved to your sim in which case you could get a new sim. Skittle (talk) 04:36, 10 December 2007 (UTC)

Journal Article Database

Can anyone suggest a good free-to-use journal database (is there such a thing? I'm sort of spoiled by my memories of computer labs at school...they always seem to have access to those kind of things)? I'm writing a short research paper, and I'd like to flesh out my works cited with a few off-line resources. Love,70.181.41.1 (talk) 16:33, 9 December 2007 (UTC)

Pubmed is free and pretty good. Does not cover some plant journals. An excellent non-free, but often available at libraries, database is Web of Science. David D. (Talk) 16:40, 9 December 2007 (UTC)

Thanks. I'll make a note of that (the PubMed is going to be fun to dig around in, I appreciate it). I should be more specific. I'm writing a quick five page overview of lunar formation, focusing on the strengths and weaknesses of the giant impact hypothesis. The reference links from the article were helpful, but I feel like some off-line citations will give it an air of respectability. 70.181.41.1 (talk) 16:59, 9 December 2007 (UTC)

You may also want to take a look at scholar.google.com. I've had luck with articles linked from their database, when going to the journal's website doesn't work. I'm not sure if perhaps Google is a subscriber (much like your library was at school) or what, exactly, but it seems to work often. (EhJJ) 18:43, 9 December 2007 (UTC)

What's your field? Physics preprints are almost always nowadays posted at the ArXiv. SamuelRiv (talk) 19:01, 9 December 2007 (UTC)

How much does solar energy cost to produce ?

How much does solar energy cost to produce? —Preceding unsigned comment added by 68.218.19.20 (talk) 17:20, 9 December 2007 (UTC)

(Added title to question) SteveBaker (talk) 17:34, 9 December 2007 (UTC)

For the time being solar energy is free. --Ouro (blah blah) 18:31, 9 December 2007 (UTC)

I assume they mean the capital costs, etc., of a power system which converted solar energy to electricity. --24.147.86.187 (talk) 21:47, 9 December 2007 (UTC)

It's not just capital costs either - eventually they fail and have to be replaced. In a large scale installation, the panels need to be cleaned to remove dust and dirt that would otherwise reduce their efficiency. However, it's not going to be anything like as expensive as maintaining any other kind of power station. The biggest problem is the capital cost. SteveBaker (talk) 23:21, 9 December 2007 (UTC)

Indeed. Not only is solar energy not free in practice, it's so not free that in general, it can't really compete with fossil fuels yet. That is, the equipment required to capture and use that "free" energy is so expensive per unit of energy captured that it's usually cheaper to use "conventional" sources instead. (The situation is changing, but slowly.) —Steve Summit (talk) 23:38, 9 December 2007 (UTC)

Well, it all depends on how much solar energy you're producing. Small solar panels, like ones for solar powered calculators, sell for under $10. But solar power plants, like these, can cost quite a bit more. This solar power tower, for example, cost about $40 million (USD) to build. So, your question is like, "How much does a motor powered vehicle cost?" It depends on whether you're talking about a scooter or a helicopter and if you're including other things, like long term maintenance. -- HiEv 00:42, 10 December 2007 (UTC)

But even there, in a calculator, is an example of the problem in microcosm. You can buy a AA battery for about 50c - so for a $10 solar cell, you can get 20 batteries. The little 4-function calculators that come with solar cells use so little current that they'll easily run for a year of normal use on one battery - so if you'd spent your $10 on batteries instead, it would take maybe 20 years for you to finally discover that you'd have been better off using a solar cell. The trouble is that nobody keeps a calculator for 20 years because they break, get lost or are outmoded. What's worse is that if you'd invested your $10 in the stock market (with an average return of about 5% per annum), then your interest would be 50c per year - which means that you could keep yourself in batteries for the rest of your life for the price of those solar cells. Sure, you can quibble with the numbers (I don't think calculator solar cells cost anything like $10) - but you get the point. It's not always obvious that "free" electricity is something you can afford to buy. SteveBaker (talk) 03:50, 10 December 2007 (UTC)

But (I have to have this but) there's the additional costs that come into play. Say you went with the batteries, and not the solar cell, it would be good to count in the costs of disposal of the batteries and/or their recycling. I know it's usually something negligible or something that the usual calculator user never ever ponders on or cares about, but still, somebody has got to take care of the refuse. There's also the costs (to the environment) of the production of those umpteen batteries vs the costs (to the environment) of solar cell manufacture. If we're discussing everything, then it should be everything. --Ouro (blah blah) 06:59, 10 December 2007 (UTC)

I think the $10 figure for a calculator solar cell is too pricey, by an order of magnitude or so. Cheap solar-powered calculators are a giveaway item at conferences and such. Here's a calculator for $2.75, retail, in single quantity. Here are calculators for as little as $1.09 in quantity. The solar cell itself must be under a dollar. -- Coneslayer (talk) 12:43, 10 December 2007 (UTC)

Does Cefdinir dehydrate you, or am I getting seriously windburnt?

This question has been removed. Per the reference desk guidelines, the reference desk is not an appropriate place to request medical, legal or other professional advice, including any kind of medical diagnosis, prognosis, or treatment recommendations.

Since you've found our article on cefdinir already, there's not much more we can add. The volunteers at the Reference Desk aren't qualified to diagnose your condition—and even if they were, it's difficult to do a proper examination over the internet. You should speak to a trained and licensed professional – your physician or pharmacist – about your concerns. TenOfAllTrades(talk) 19:43, 9 December 2007 (UTC)

Oh, sorry. I'll ask the doctor at my followup. MalwareSmarts (talk) 19:55, 9 December 2007 (UTC)

NASA's COBE (Cosmic Background Explorer) Satellite

COBE produced an Infra-Red picture, that was unveiled by Eli Dwek at a meeting.

Where and when was this meeting?

Was it, for example, at the Conference held in College Park, MD - in April 1995? Anyone know? - I'm Peter Lamont. —Preceding unsigned comment added by Astrocat0-1 (talk • contribs) 18:52, 9 December 2007 (UTC)

December 10

Fan curve calculation

I'm looking for a fan curve (pressure-volume) for a particular fan - I've been told it's an "RB21 AVON" - and failing that, I've been told to find a "fan formula" so that it be calculated. Is there such a formula (with diameter, air density, and some other coefficients), or are these determined empirically? 150.101.23.102 (talk) 00:26, 10 December 2007 (UTC)

I've only ever seen this done empirically, with a device that measures volume/area/time of air coming out of the fan. Certainly far easier than solving some convoluted aerodynamics equation. Someguy1221 (talk) 00:39, 10 December 2007 (UTC)

Well, I've possibly found a more complicated formula - see here (measuring method, no anchor, about 1/3 down) - but that still looks like more of a "how to use a test rig to plot the curve" than a full CFD with fan parameters. 150.101.23.102 (talk) 01:02, 10 December 2007 (UTC)

Actually, assuming that I did have to perform a CFD analysis on it, what software would I be looking for? 150.101.23.102 (talk) 01:33, 10 December 2007 (UTC)

LED blinking with 555

How many LED's can I control with a 555 timer? It has a nominal output current of 200 mA, if a LED needs 20 mA — I believe this is a realistic value, correct me if it is not — I'll be able to supply 10 LED's. Am I right? Thanks in advance for your help. 217.129.241.169 (talk) 01:47, 10 December 2007 (UTC)

In theory, yes, but look at your datasheet for more accurate information. But I don't think it has any current limiting mechanism built-in so you will still need to have a resistor in series. --antilived^{T | C | G} 04:51, 10 December 2007 (UTC)

Yes, I'll obviously need to insert resistor in series with the LED's, my doubt was just related with the driving capacity of the 555. Meanwhile I saw a project similar to mine and it used a 555 to drive 20 LED's. Thanks! 217.129.241.169 (talk) 13:31, 10 December 2007 (UTC)