Wikipedia:Reference desk/Science

Reference Desk

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 Unanswered questions If you find that your question has been archived before being answered, you may copy your question from the Archives into a new section on the reference desk.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

May 18

average time of sunrise and sunset

On average, what time does the sun rise and set? I don't think it matters because it is an average, but my latitude is approx 35 north. Thanks. 152.163.100.74 01:07, 18 May 2006 (UTC)

Maybe this utility would help? --Chris 01:19, 18 May 2006 (UTC)

On average, it should be 6 a.m. / 6 p.m., as far as I can tell (daylight saving time and time zones nonwithstanding). — Knowledge Seeker দ 06:55, 18 May 2006 (UTC)

If you average it over the entire year and assume that your clocks are set to local solar time (which is rarely the same as the standard time in your time zone), then, yes. But even assuming this, at 35°N, the variation over the course of the seasons is considerable (several hours either way). The link given by Chris seems pretty good. — QuantumEleven 09:16, 18 May 2006 (UTC)

Also, the 6-to-6 average is a bit off because sunrise and sunset are measured from the first and last moment any part of the sun is visible, not when the center of the sun is visible. Consequently, days always average slightly longer than nights. — Lomn Talk 13:57, 18 May 2006 (UTC)

It's also very much off because daylight saving time is used in more than half of the year (this might not apply to your part of the world of course) so it's more like 6:30 and 18:30. But that's only if you live on exactly the central latitude longitude for your timezone, for example, E15° for CET/CEST; otherwise you have to subtract four minutes per every degree you are more to the east from that latitude longitude.

See the book Öveges József, Játékos fizikai kísérletek (Nemzeti Tankönyvkiadó, Budapest, 1995) – b_jonas 15:35, 18 May 2006 (UTC)

Nem mindenki beszél magyarul.. :) --BluePlatypus 20:08, 18 May 2006 (UTC)

combustion

what product is formed if incomplete combustion occurs in a car engine? —The preceding unsigned comment was added by 142.165.111.39 (talk • contribs) .

Many different substances — that's part of the problem. If it were just one substance we could focus all our resources on eliminating that one thing. You're probably looking for carbon monoxide but there's also nitrogen oxides and polycyclic aromatic hydrocarbons. —Keenan Pepper 02:18, 18 May 2006 (UTC)

Homework question I believe. Standard Grade Chemistry or something. Tsk tsk. The SG answer would be "Carbon Monoxide and oxides of nitrogen" however.

What, then, would the SG pundits consider to be the nitrogen oxide which represents complete combustion? Nitrogen dioxide only? I would have thought that the correct answer to this homework question would be simply "CO". Further questions might lead to why there are also oxides of nitrogen in the exhaust gas.G N Frykman 17:39, 18 May 2006 (UTC)

I'm doing GCSE chemistry, and we get told CO and NO_X. Philc _T^E_C^I 17:52, 18 May 2006 (UTC)

Ditto. But if your fuel sucks, you might get other stuff in there too, like sulfur oxides. --M1ss1ontomars2k4 | T | C | @ 23:54, 18 May 2006 (UTC)

I was merely giving the answer which I was taught, and is accepted in Scotland by the exam board. We were only taught "carbon monoxide and oxides of nitrogen". It doesnt specify which ones exactly. But the question doesnt ask what ALL the products are, just to name some. And as many go beyond the scope of Standard Grade/GCSE chemistry, I believe the given answer is suitable.

Why can birds sit on powerlines?

Why can birds sit on powerlines? -- Mac Davis] ⌇☢ ญƛ. 04:42, 18 May 2006 (UTC)

There is no voltage, i.e. potential difference, between the bird's legs; thus, no current passes through it. If it would touch another powerline or the ground at the same time, bad things would happen. –Mysid^(t) 04:56, 18 May 2006 (UTC)

Because powerlines are normally insulated --Fuhghettaboutit 06:07, 18 May 2006 (UTC)

Power-lines are bare, but anyone can sit on one as long as they don't complete an electrical circuit with another power-line or with a supporting pylon or earth. Passerines like to sit on power-lines because it is their nature to perch. --Shantavira 07:03, 18 May 2006 (UTC)

Power line electrocution is a killer for the big raptors. See this: [1] Power companies put a lot of effort into reducing the carnage. --Zeizmic 12:23, 18 May 2006 (UTC)

Can you explain why they would kill raptors but not other birds?ike9898 13:36, 18 May 2006 (UTC)

It's a matter of size: larger birds are more likely to contact different wires, or wire+pole, or wire+tree, or whatever other lethal combination. — Lomn Talk 13:55, 18 May 2006 (UTC)

Large birds are likely to develop more potential difference across their bodies when in the strong electric field around a high voltage power line. This is why maintenance men working on live OH 275kV etc lines wear equipotential conducting suits (so the electric field cant cause curernts to pass thro their bodies. Anyway, any birds you do see on the supergrid lines are usually sitting on the ground wire (the top one) Thats propbably cos they can feel the field if they fly any closer to the live conductors. 8-)--Light current 14:18, 23 May 2006 (UTC)

When a bird sits on a power-line, it is not grounded, as electricity rushes to the ground. If the bird happened to spread its wings and hit the pole, well, you'd have a fried bird. What I don't understand is, aren't power lines really, really hot? Can't electricity burn you?

If power lines were really, really hot, it would be a terrible waste of electricity. Some power is lost, but it depends on the resistance of the wire used which is kept low enough to reduce power loss to acceptable amounts, and the very high voltages also reduce power loss for particularly long wires. The power loss is a trade off between voltage/safety issues/cost of wires/extra weight of wires (requiring more support)/other things I've overlooked. Notinasnaid 19:12, 18 May 2006 (UTC)

Power lines are warm, from electrical resistance. They don't get very hot, though, because the hotter a wire is, the higher the resistance, leading to runaway heating and the wire catching fire.

Yes, electricity can burn you, but only if it's flowing through your body. For a bird sitting on a power line, there's nowhere for the electricity to go, so it doesn't fry the bird. --Serie 19:17, 18 May 2006 (UTC)

Not quite true. See my post above about electric fields--Light current 14:20, 23 May 2006 (UTC)

Ooh! I have a variant on this question. For trains that run on electrified rails, such as on the London Underground, there is a live rail. I travel on parts that are overground and so I see pigeons perching on these rails all the time. I often think that they must come close to electrocuting themselves (surely they would only need to briefly touch the ground while perching on the rail?), and ditto for the rats scurrying around on the underground parts of the system. But I've never seen this happen. Maybe it's this thing about the rails only being electrified in the area before and after a train, or is there another reason? Carcharoth 21:15, 18 May 2006 (UTC)

Ah. Following the link through electrified, I eventually found Railway electrification and the bits about the Third Rail and London Underground's Fourth Rail. Which is helping - but science-orientated explanations would be great. Carcharoth 21:23, 18 May 2006 (UTC)

And you'll notice that birds don't sit on the super high-power lines that span across more rural areas (the ones that make the loud buzzing sound). There is probably enough stray current to cause some damage, or at least prickle their feathers when they get close.  freshgavinΓΛĿЌ  06:43, 19 May 2006 (UTC)

It's actually because high tesnion power lines dont actually have the electricity inside the wire, the voltage is so high, it forms a field around the wire. That is also why the insulators are so big.

For the bird to get electrocuted, the current has to enter from one part of the body (a leg) and come out of another (another leg or the wing etc). But these two legs are 'shorted' by the conducting wire and hence, the potential difference between the points where the bird holds the wire is (nearly) zero. The current flowing thru the bird's body is in the inverse ratio of the resistances of the bird's body and the conducting wire and hardly any current flows thru the bird's body. Even if a human is to hang on to one live electric wire, negligible current would flow thru his body and nothing would happen to him. But the momeent and other part of the body touches the other wires or any path to the ground, a considerable current would flow and cause death or injury. Many birds die when they sit on one wire and peck on other wire, or when they spread their wings. -- Wikicheng 07:25, 19 May 2006 (UTC)

There's another effect. A bird is a capacitor, and there's alternate current in the wire. So the bird is charging and discharging repeatedly, and it leads to a current flowing throug its body, even if the bird is touching the wire with only one leg. Apparently it's so small that the bird isn't harmed (the corresponding resistance is R = 1/ωC; ω is 50-60 Hz, C is about 10 pF for a 10-cm bird, it gives R ~ 1 GΩ and I ~ 10 µA for a 10-kV line; IIRC a human can feel a current of about 1 mA, don't know about birds). Conscious 11:34, 19 May 2006 (UTC)

I would say that a bird makes a very poor (low Q) capacitor since its body resistace will be a few hundred ohms and the main current thro its body will be in phase with the voltage. THats what'll kill it-- not capacitive current!--Light current 14:24, 23 May 2006 (UTC)

But the voltage between bird's legs is much smaller than the voltage between the bird and the grounds. Conscious 06:22, 24 May 2006 (UTC)

Sleep

Moved from misc. 61.25.248.86 06:37, 18 May 2006 (UTC)
In high school, I used to sleep through half of my classes, but so did everyone else, so I didn't really care. After I breezed through that, I ended up sleeping a lot in University too. That was a little more problematic, and no matter how hard I faught to pay attention during lectures, a lot of the time I just couldn't keep my eyes open, and I eventually just started sleeping in a lot and going to later classes. Even now, while working, I feel incredibly tired in the morning, though I'm almost always standing up so I don't really get a chance to close my eyes (thank god).
I may be returning to school sometime soon, and I want to work a little harder this time, but I don't know how I can get over my sleepiness.
I've never really been that susceptible to agents like nicotine, THC, and caffeine, so although I recently started taking coffee in the mornings (I don't even like it) I don't really feel the effects of it. For some reason, drinking coffee or coke at night prevents me from falling asleep, though.
I generally get enough sleep (8-10 hours on working days) but it doesn't really seem to matter because I go through the whole day yawning and rubbing my eyes anyways. I am not any lazier than most people, but I know that working out in the morning will wake me up (I've tried it). My problem with that is that I don't understand why I have to resort to something so extreme (waking up before 5am!) when most people here don't seem to have any problems, even when having only slept 6 hours. Is there some kind of perpetual sleepiness condition that I might have? Anything that can help? 61.25.248.86 03:33, 18 May 2006 (UTC)

Sleep and Fatigue might link to something of use, but it's a long shot. Wikipedia is not really geared towards providing practical advice. Howard Train 05:21, 18 May 2006 (UTC)

I was posting under the impression that it might be some sort of known medical condition that could be treated. 61.25.248.86 06:35, 18 May 2006 (UTC)

You could try moving West a few time zones. The effect probably would only last for a few days though.-gadfium 06:50, 18 May 2006 (UTC)

In that case, your best bet is to have a visit with your physician. He will know best if it's some sort of medical condition or what kind of treaments might work. — Knowledge Seeker দ 06:53, 18 May 2006 (UTC)

Perhaps the quality of your rest is poor. Sleep apnea is one common condition it may be worth asking your doctor about. --Bad carpet 10:27, 18 May 2006 (UTC)

Insist that your doctor sends you to a sleep clinic. Apparently, many doctors still don't do this for sleep disorders. There are about a dozen possibilities (types of disorders), each with a different treatment. --Zeizmic 12:26, 18 May 2006 (UTC)

Maybe you need to sleep more, like go to sleep before 22:00 atleast, as I'm guessing you don't. And also, you said drinking caffine drinks at night seems to keep you awake, well as a bit of a no brainer, don't do that anymore. You can always try pep up pills of some sort. Philc _T^E_C^I 17:50, 18 May 2006 (UTC)

I strongly agree with others who suggest you visit a physician specializing in sleep disorders, since your extreme sleepiness is unusual for sleeping up to 10 hours a night. However, you might also try ginseng in the meantime. Many products containing this herb have a very low potency; your best bet is to try to find a concentrated form and make a tea of it. --Ginkgo100 18:47, 18 May 2006 (UTC)

You could try something physical like a 5k run to start the day or something, that keeps me wide awake for ages. Philc _T^E_C^I 19:54, 18 May 2006 (UTC)

Rust never sleeps. --DLL 20:55, 18 May 2006 (UTC)

What? Philc _T^E_C^I 18:40, 19 May 2006 (UTC)

Actually, I did move west... 13 hours west in fact. I didn't sleep at all the first day and it didn't help at all : 8! Also for that reason just "going to visit my physician" isn't really that easy. I don't trust the doctors here (they tend to overprescribe medicine in huge quantities and charge you hell for it too), and I don't have a physician anyways. I'd like to handle it by myself (I'm that kind of guy ... like I broke my fist on a wall and I just stuck it out).

I'm pretty sure the quality of my sleep is poor, I've always been a little bit of an insomniac. When I don't have work my sleeping pattern gradually shifts later and later until I end up sleeping after the sun rises, and it takes a lot of concious effort (and lying awake in my bed for hours) for me to keep my patterns from shifting.

If I sleep more, it keeps me from flat out falling asleep, but I never really stop yawning, and if I'm sitting down I always migrate to more sleep-like positions. Lately I've been waking up at 6am for work, and I find it quite easy to sleep at 10pm. It feels like I'm going into a much better, deeper sleep, but I can never seem to get the hang of waking up so early, and I always end up twice as awake in the evening as I was during the rest of the day. I kind of consider myself the ultimate anti-morning person. : 8.

I'm pretty sure taking a 5km run in the morning would work, but can you honestly say that you'd be able to do that 6 days a week, before 6am? I know that it might be the only solution for me though. 61.25.248.86 06:19, 19 May 2006 (UTC)

I'm not a doctor... Do you drink vitamins? ellol

Personally I would suggest exercise of almost any sort, at any time during the day (doesn't have to be the morning). One gets better quality sleep when they've been physically active during the day. Try biking to places you need to go to closer than 5 miles away rather than driving or taking the bus. - McCart42 02:27, 24 May 2006 (UTC)

PDF files to WORD files.

Hello, just recently i donwloaded lots of ebookz, most of them in pdf format. I found that reading from pdf files is really uninteresting. The way the pages scroll down, and everything else works is too uncomfortable for me to enjoy the reading. So is there any softwares avaliable for converting pdf files to word (".doc") files. Or alternatively, is there any way to copy all the text and images from a pdf files, as it is, to a word file? I tried to copy, but both cannot be copied simultaneously. So is there a solution for me? Thank You.

See Converting PDF files to Microsoft Word files. -- Mac Davis] ⌇☢ ญƛ. 09:00, 18 May 2006 (UTC)

This kind of conversion is only possible in certain circumstances and is generally not meant to happen. If a PDF was created from text (and has the proper permissions) you can select the text and copy it into Word, but you'll have to copy the pictures manually. If they were made by scanning in the text, you're completely out of luck.

Short answer: you can't.

Also, I don't understand what you mean by "uncomfortable to read" - you know that Adobe Acrobat reader (which I presume you're using) has options on how it should treat scrolling (for instance, by page, continuously...). Try playing around with these options instead, and try zooming in/out to make the text a comfortable size for reading. — QuantumEleven 09:11, 18 May 2006 (UTC)

Some people just don't like to read lengthy things on the computer screen. And if it is more than 10 pages you just gotta print it out! -- Mac Davis] ⌇☢ ญƛ. 11:40, 18 May 2006 (UTC)

That question recurs periodically. --DLL 20:53, 18 May 2006 (UTC)

If you have a later version of microsoft office, you can print to the Microsoft Office Document Imaging something something. Then, you can use the program to OCR the text back into msword. In theory, at any rate. --M1ss1ontomars2k4 | T | C | @ 23:51, 18 May 2006 (UTC)

Your problem isn't just Acrobat. I hardly think reading a word document would be much more enjoyable. If you refuse to print them out you could always buy an e-book type utility, many/most of which support Acrobat files, but if you had the money to buy one of those you probably wouldn't mind printing them out in the first place.  freshgavinΓΛĿЌ  06:36, 19 May 2006 (UTC)

I mention (purely hypothetically, of course) that open-source PDF readers are easily available, such as xpdf. You could, hypothetically, get the source code, and comment out the places where it won't let you do things (such as print the file) based on permissions. I looked at the code once (hypothetically) and it appeared fairly trivial to find these code snippets and circumvent them. Of course if you're in the United States there's that pesky DMCA—I think the prescribed penalty is breaking on the wheel. --Trovatore 16:26, 23 May 2006 (UTC)

"92% water"

I want to know how much water is in the flesh of a watermelon. Searching the wikipedia article and Google I see the figure 92% over and over again, but no where seems to say if this figure includes the rind and seeds or not. I'd like to know how much of a watermelon is water, excluding the rind and seeds. (This is to settle a bet) —Pengo 10:27, 18 May 2006 (UTC)

Is that 92% by volume or 92% by weight? Ohanian 11:10, 18 May 2006 (UTC)

Would have to be by weight; watermelon is much too airy to be 92% volume water. — Lomn Talk 13:53, 18 May 2006 (UTC)

If you're betting on it, then I'd suggest you take a watermelon and come up with a way to measure it by yourselves. By googling it seems that different percentages are mentioned, depending on the site and watermelon in question (typically 90–97%). No site mentions if the number is for the whole fruit or the flesh only, though. One site says that "The flesh of this succulent fruit is over 90 percent water" (italics by me), so if you trust them, at least it is over 90. –Mysid^(t) 15:29, 18 May 2006 (UTC)

One could puree a known mass of rindless, pipless watermelon flesh, boil it, and gently heat till dry. Assuming there is not a significant mass of other volatile compound boiling off, weighing the dry stuff would give you your own answer. -Seejyb 19:52, 18 May 2006 (UTC)

NBME Question bank - STEP1 USMLE

NBME Question bank - STEP1 USMLE hi, i am lookin for question bank series book, that is used to prepare for step 1 USMLE exam. Can any one let me the latest edition details along with the author name. If referenced to publications then can u please let me know the publisher name.

thanks.

Fish flatuence?

This might seem like a crazy question, but does anyone know whether fish produce flatuence or not?--Bjwebb (talk) 18:25, 18 May 2006 (UTC)

Google for "fish fart" and you'll quickly find this. --Kainaw ^(talk) 18:54, 18 May 2006 (UTC)

Hummingbird Nest

Last week a hummingbird built a nest in my backyard and laid a single egg. The next day it was gone. My questions: How rare is it for hummingbird to lay a single egg rather than two? Can a mother pick up an egg and carry it away after she has laid it?

It's possible something sinister happened to the nest. An adult hummingbird would have no way of moving the nest nor the egg. Mortality in baby birds is very high. --Ginkgo100 03:50, 19 May 2006 (UTC)

Carry an egg? Would that be an African or a European hummingbird? ;-) --Swift 05:10, 19 May 2006 (UTC)

Garden soil safety

I've just moved into my current house, and I would like to be sure that the vegetables I am planting in the back yard will be safe for my family to eat.

Plants grow very nicely in the soil, and it is full of earthworms and other small animals. My concern comes from the fact that when I dig, I find a certain amount of old trash, and pieces of glass, brick, and concrete, and that the neighborhood, Hampden, Baltimore, Maryland, was once the home of many old industrial sites.

I have also seen among the red earthworms a few bright yellow ones, looking not unlike the worm shown in this Nature article, "Don't eat yellow worms". The article suggests that this coloration may be a sign of high levels of arsenic or copper.

What is a sensible level of caution on this question? Is there a way to find out the history of a particular piece of land? All the soil testing services I have found are for pH, nutrients, or parasites; is there an easy way to have the soil tested for contaminants or toxicity?

Thank you; 128.220.220.95 18:59, 18 May 2006 (UTC)

This could be a community-wide ecological issue, not just your personal gardening problem. Plants, insects, birds could all be affected. I would contact my local university for advice (e.g. http://www.umbc.edu/biosci/ UBMC). Maybe they would see this as an opportunity for research, more than just pointing you in the right direction. --Seejyb 20:54, 18 May 2006 (UTC)

For city gardens, it might be best to do 'planter gardening' or raised beds. See a gardening book on this. That way you are assured of fresh, safe organic material. --Zeizmic 23:43, 18 May 2006 (UTC)

You could try contacting your local council or environment agency to see if they have any information on the safety/composition/pollution levels of the soil nearby. AllanHainey 13:54, 22 May 2006 (UTC)

Technology: Developement

Here's a question for all you tech people out there. If human developement is continuously improving computers, palm pilots, and everything else, why is it we are still stuck in an age where we rely on the most costly almost 80year old technology of four wheels on the ground? shouldnt we be in a more economical way of hovering either only a couple inches off the ground or couple miles above the ground and in a safe way. I know movies are just movies, but we should still be at an age where we move past prehistoric wheels?

And a question linking to the top: Why is it that oil and gas are still the dominant source of fuel in the world? Souldn't we be in an age of alternative fuels, to almost electrical technology that can allow us to constantly reuse and recharge? Thank you for your imput. --134.29.205.119 19:00, 18 May 2006 (UTC)

Infrastructure for production, storage and distribution of a new fuel system would be very expensive to install. Think about it: you would have to get rid of every gasoline/diesel/propane station and replace it with whatever, a hydrogen tank center or something. The fuel companies would hate that. And they would lose all their institutional knowledge. A changeover period of some years, maybe a decade, would be necessary. Do you remember when leaded fuel was outlawed in the 80s? That was a big deal for many people. This would be much more challenging. Refineries, fuel companies and governments have vested interests in retaining the current fossil fuel power method. However, cars become more fuel-efficient all the time, so every year our supply of fossil fuels will actually last longer. Vehicles also pollute in decreasing amounts with every new model. Now, if you want to become an elected legislator, and take your ideas to government, you can. There you will encounter stiff resistance in the form of lobbyists, other politicians, and just plain regular folks who downright don't like change. Change happens slowly. That's why laws like the Clean Air Act are important, because they force manufacturers to steadily improve their products. Eventually a target can be set that is impossible for an internal combustion engine to achieve, and then you will get your hovercars. But the executive has to take the plunge on that, and at present they aren't; they are actually moving back from it.--24.80.70.174 19:15, 18 May 2006 (UTC)

Why do you say "most costly"? Doesn't it seem like a hovercar (a HOVER...CAR) would be unimaginably more expensive than something very basic that's been streamlined and perfected over about a century? Also, there's the basic problems with floating in the first place. Anti-gravity has been studied for quite a while, and the closest we've gotten is the age-old trick of holding two magnets together. Maglev trains are good that way, except that they only float a little bit, and never leave their pre-defined tracks. Mass transit is, like all other things that start with "mass", rather more economical that individual transportation if everyone's going in the same direction, so it's got that going for it as well, but I don't think it's quite the answer you're looking for. There have also been efforts to combine cars with tiny airplanes, in fact Popular Science has an article on exactly that this month, but have you ever been to an air traffic control tower? I have. It's hectic as it is. Can you imagine putting the same retards (the same tens of millions of retards, compared to the relatively few commercial jets in the air) that get into fender benders on residential roads into planes that go five times as fast, a few hundred feet above the ground? It'd be chaos. Really, apart from the fact that it's in many cases impractical and unpopular to make such major changes, there's very little reason for it in the first place. Wheels are awesome. Engines are practical. And what could be cooler than combining effectively frictionless objects (wheels don't rub the ground, do they?) with a powerfully explosive liquid and a few tons of metal? It's just a shame we're running out of the second one. Black Carrot 22:19, 18 May 2006 (UTC)

About the hypothetical control tower operators you mentioned...it is, at least, an interesting thought of a realistic concept for skilled labour positions... -Tim Rhymeless (Er...let's shimmy) 03:47, 19 May 2006 (UTC)

In the 1970s, New Zealand supported many vehicles running on Compressed natural gas, with a substantial proportion of petrol stations installing the tanks for vehicles to refuel. It was probably Government subsidised, but it seemed to work rather well. It was much cheaper than petrol, but vehicles had somewhat less power. I ran a CNG-powered car for some years. Liquified petroleum gas was also available as a vehicle fuel, but less popular, as it was more expensive than CNG (still cheaper than petrol, and without the powerloss of CNG). When petrol prices declined in the mid 1980s, these alternative fuel systems largely disappeared in New Zealand, but I understand they're still in use in Argentina and Chile.-gadfium 08:53, 19 May 2006 (UTC)

It all comes down to a cost and benefit analysis. I spent several hours today making notes using a pencil on a piece of paper. Pencils are several hundreds of years old, paper several thousands. Why do I still use such 'primitive' technology? Why don't I use a laser pen on a smart pad which inputs my writing directly into a computer? Because the cost of doing it would be greater than the benefit I get out of doing it - very little, in fact, as the same information is written down either way, but the laser pen, smart pad and PC are vastly more expensive than by HB pencil and sheet of paper.

It works the same way with most of the examples you mentioned. Why don't we have flying cars? Because at our present technological level, the benefit we would get from flying cars (faster journeys) is far outweighed by the costs. A flying car would be far more expensive than a regular car (a jet aircraft engine, which is what we'd probably use, easily costs several tens of millions of dollars). The fuel consumption would be enormous (so, more cost, not to mention the environmental damage from the exhaust). The risk to the occupants is far greater (not just in terms of collision (as Black Carrot rightly points out), but if the engine fails, you tend to fall out of the sky and end up as a splotch on the landscape). With conventional cars, boy racers and their roaring machines are at least confined to the roads, with flying cars, you could well having them buzz your house at ten meters above you at 3am. I could go on... I think you get the idea.

Rather than private flying transport it's worked out that, for economic and safety reasons, airliners have been more successful than private planes. That said, there is finally a bit of action in what was the moribund private aviation market, centred around two areas; at the very low end amongst homebuilts, ultralights and the closely related light sport aircraft category. Further up, the prospective very light jet aircraft might put the "air taxi" within economic reach of a lot more people. So over the next few decades, while we may not have the flying car, private or small-scale charter flying may become a lot more popular assuming that safety and environmental issues don't shut it down again (particularly in the case of the VLJs, which chew quite a lot of fuel per passenger). --Robert Merkel 14:28, 19 May 2006 (UTC)

The bottom line: just because something is 'old' doesn't mean it shouldn't be used.

And to answer your second question, our article on future energy development should go some way towards explaining why all forms of energy production have their advantages and disadvantages. — QuantumEleven 08:57, 19 May 2006 (UTC)

Diaphragm (obscure science meanings)

I recently expanded the diaphragm disambiguation page, but some of the terms seem to lack articles, and some other terms need someone to explain them properly. Does anyone here know enough to expand on the battery use of the word diaphragm, or the more general anatomical term found in organisms other than humans (such as bryozoans and gasteromycetes). Also, I am now confused about how diaphragm relates to septa and septa (biology). Can anyone clarify the different meanings of these terms? There seems to be a fair bit of overlap.

Oh, and I know it is not science, but if anyone knows enough about engineering and architecture to explain diaphragm wall, that would be great as well! Carcharoth 20:22, 18 May 2006 (UTC)

It takes the place of the salt bridge that is used in the Galvanic cell. Hope this clears things up. --M1ss1ontomars2k4 | T | C | @ 23:47, 18 May 2006 (UTC)

That has helped. Thanks. Have a look at diaphragm and see if what I wrote was clear enough, at least for now. Unfortunately, there is confusion at the relevant articles:

• Galvanic cell
• Electrochemical cell
• Electrolytic cell

So hopefully someone will clear that up! THanks again. Carcharoth 01:49, 19 May 2006 (UTC)

Micrognathism

Does anyone know where I can find a photo, or at least a diagram showing micrognathism in humans? I've been having a bit of trouble finding anything readily online. -Tim Rhymeless (Er...let's shimmy) 21:38, 18 May 2006 (UTC)

I'm not sure what types of pictures you're looking for; if you're looking for more anatomical pictures or just pics of people with the syndrome. Anyhoo, I googled 'Micrognathism pictures' and found this site, a plastic surgery site it seems, with before/after pics. I suspect if I looked further I'd find more, the search returned a lot of sites that hadn't been anywhere near the top of the google results for just 'micrognathism'. You might have even better luck googling 'micrognathism "plastic surgery"' or 'micrognathism "cosmetic surgery"' because those sites usually have galleries of before/after photos.--Anchoress 22:47, 18 May 2006 (UTC)

Mosquito size

What is the size of the biggest mosquito ever? I killed one today, and want to be sure it was not the biggest available model. --Roundedge 21:43, 18 May 2006 (UTC)

"Size varies but is rarely greater than 15 mm (0.6 inch)" Mosquito. --Halcatalyst 15:43, 19 May 2006 (UTC)

Was it possibly a crane fly instead? Melchoir 23:04, 19 May 2006 (UTC)

Heart Regeneration

I have open on my lap this month's (that is to say, June's, because ever magazine I've ever received fell through a wormhole on the way) issue of Popular Science, and I'm looking at rather a curious article. It's centered around some of the most recent work of Hydra Biosciences, a company apparently dedicated to the dream of effective regeneration of dead and damaged tissue. My question is, what do you think of this? Does it sound like something we can look forward to in twenty years, or someone just trying to get attention? Black Carrot 21:55, 18 May 2006 (UTC)

For what it's worth, PopSci really is filled with pop-sci. According to today's technology, what the article discusses may be feasible in the future, which is much unlike cold fusion. Cold fusion, thermodynamically, doesn't make much sense. At least this does. --M1ss1ontomars2k4 | T | C | @ 23:44, 18 May 2006 (UTC)

speed of light

ok, so my perental told me when you approach the speed of light time slows down. i dont understand how or why. i got the following idea: first since time is an arbitrary concept agreed upon by human(i would like to know what exactly time is if im wrong, please) say speed wasnt measured int distance/time but, oh banannas for example. so the speed oflight would be say 300 banannas, 0 banannas being completely still. as an object increases banannas time begins to slow down; so at 150 banannas "time" is twice as long(for what though? the observer or the object?) so if at 1 bananna the object traveled 6 feet at 150 banannas 1 minute would become to, but the object is still goin at 150 banannas, so now it travels 12 feetin a "minute" because it has twice as much time to travel at the same speed. pretty much i would greatly appreciate someone telling me why is it impossible to reach the speed of light, the questions in the parenthese and wats wrong with my example --69.140.210.163 22:05, 18 May 2006 (UTC)Artem

My understanding is that as an object accelerates towards C, it's mass increases, and thus the amount of energy required to accelerate increases towards infinity. In other words, it would take an infinite amount of energy to accelerate to C. Raul654 22:07, 18 May 2006 (UTC)

Sorry to intrude, but you mean "its", not "it's". --M1ss1ontomars2k4 | T | C | @ 23:42, 18 May 2006 (UTC)

Let's try by analogy.

as you approach the speed of light, the rate of passage of time slows down.

as you reduce the clock rate of CPU, the rate of computation slows down.

but you will not noticed that the rate of time slows down.

but a computer program will not notice that the rate of computation slows down.

Unless you observe an external stationary processes (like your friend on earth).

Unless the computer program references an external real time clock.

The reason time slows down is because all (chemical/nuclear) reactions slows down as light "slows down".

Ohanian 22:18, 18 May 2006 (UTC)

For what it's worth, we do have an article on Special Relativity, which is the theory you're talking about. Black Carrot 22:33, 18 May 2006 (UTC)

can someone please clarify:

what causes the mass to increase? thanks again --69.140.210.163 23:28, 18 May 2006 (UTC)

Yeah, actually I need help on this too. --M1ss1ontomars2k4 | T | C | @ 23:42, 18 May 2006 (UTC)

---

Question: what causes mass to increase as an object approaches the speed of light?

Answer: Now assume that you are applying a constant force on an object.

  Remember that F = M * A

  You can rewrite that as   F = M * dV / dt

  Re write as  M = F * dt / dv  

  So what you have is Mass is Force times rate of change of time per velocity. 
  Now listen carefully. As an object approaches the speed of light, 
  it takes longer (more time) and longer to gain an extra/additional velocity 
  (say an additional 1 meter per second). 

  So dt / dv becomes larger and larger. 

  Therefore the Mass is getting larger and larger.

Ohanian 08:03, 19 May 2006 (UTC)

Unfortunately, the monkeys eat the bananas, and "banana time" ceases to exist. You should have tried apples instead. Carcharoth 00:47, 19 May 2006 (UTC)

According to the special relativity article, "Mass and momentum - when gaining momentum the apparent mass of an object increases as well as the energy (giving the famous E=mc2 equation.)" In other words, just as the relationship between time and distance warps at extremely high speed, so does the relationship between mass and energy. Black Carrot 01:59, 19 May 2006 (UTC)

Just to complicate things a little, light can apparently now travel [backwards], faster than the speed of light.--Shantavira 08:09, 19 May 2006 (UTC)

Sea urchins

how many teeth do sea urchins have.

I haven't checked yet, but does sea urchin help? --HappyCamper 23:57, 18 May 2006 (UTC)

You didn't want to guess five? :-) Carcharoth 00:42, 19 May 2006 (UTC)

Those teeth form an Aristotle's Lantern. But do not play discordianist theories here. --DLL 19:30, 19 May 2006 (UTC)

May 19

Does dioxygenyl act like a normal ion?

Can dioxgenyl (O₂⁺) bond with say, chlorine, to form something like O₂Cl?

Try Chlorine dioxide. Whether or not dioxygenyl is actually present as one of the intermediate steps in the chemical reaction is not clear. The reaction mixture shown is a strongly acidic solution, but I have no idea what the intermediate steps would be. Carcharoth 01:26, 19 May 2006 (UTC)

My guess is that the chlorine is positive. What I'm really asking is, do radicals essentially act like ions?

I seem to remember that this ion was vital in the discovery of inert gas compounds. See xenon. G N Frykman 18:18, 19 May 2006 (UTC)

Formula

In the kinetic theory of gases what is the formula of P?--82.148.105.112 03:40, 19 May 2006 (UTC)

P is pressure, force divided by area. See [2]. alteripse 04:10, 19 May 2006 (UTC)

So "what is this formula tells us about <1/2mv²> in the kinetic theory of gases or other formula similar to it"

Sorry, the question as asked is uninintelligible. Please restate in English and one of us may try to answer. alteripse 10:35, 19 May 2006 (UTC)

See our article kinetic theory, it contains the formula. Conscious 11:18, 19 May 2006 (UTC)

Still unanswered..NBME Question bank - STEP1 USMLE

hi,

NBME Question bank - STEP1 USMLE hi, i am lookin for question bank series book, that is used to prepare for step 1 USMLE exam. Can any one let me the latest edition details along with the author name. If it can be referenced to publications then can u please let me know the publisher name.

thanks.

Do not post the same question on multiple Reference desk pages, and be patient. If it is here, someone is bound to look at it. Google turns up a few pages, perhaps start from there? --Ouro 06:27, 19 May 2006 (UTC)

plants & water

Since recently, we have a Venus Flytrap and a Sarracenia in our home. Following wiki-instructions from the Venus Flytrap article, I am watering them only with distilled water, and happily they seem to be doing very well (touch wood). Yesterday my partner went shopping and mistakedly brought back a bottle of deionized water instead of distilled water. Can I also use this to water them or not? Thanks for info. --JoelAbend

Yes. See deionized water. --Shantavira 08:14, 19 May 2006 (UTC)

Just a slight caution. Deionized water can become fairly acidic when stored by absorbing CO2 from the air (I can't remember the exact process). Anyways, this sometimes causes problems with very sensitive equipment when deionized water is used. It probably isn't a concern for your plant, unless they are very sensitve to slight pH changes. --Chapuisat 14:01, 19 May 2006 (UTC)

Actually, I believe Venus Flytraps prefer acidic water, so if anything it would be an advantage. --Ginkgo100 19:45, 19 May 2006 (UTC)

center of mass of the Universe?

do we have a discussion of the "consensual" inertial frame of reference of the Universe somewhere, defined, I suppose, by the distribution of background radiation, and (possibly) by the center of mass of the Universe (which I realize may lie outside the Universe for geometrical reasons)? Are there any practical effects tied to the existence of such a de-facto preferred inertial system? Can we measure our speed relative to it? dab (ᛏ) 09:08, 19 May 2006 (UTC)

Yes, there's only one frame of reference where MBR has no dipole component. But if we assume that the Universe is homogenous on the large scale, its centre of mass if nowhere (or anywhere, if you like). Conscious 11:16, 19 May 2006 (UTC)

Surely the centre of mass of the universe would be where all of the unvierses gravity pulling on you is perfectly balanced, so that you never move. Philc _T^E_C^I 18:46, 19 May 2006 (UTC)

The usual definition of "center of mass" is problematic if the universe is infinite, which it appears to be. -- SCZenz 00:20, 20 May 2006 (UTC)

The Universe is not infintely big. Philc _T^E_C^I 17:22, 21 May 2006 (UTC)

precisely, and what can we say about the frame of reference where there is no dipole component? Is there a discussion of this somewhere on WP? What is our speed relative to it? dab (ᛏ) 20:19, 19 May 2006 (UTC)

380 km/s, according to Cosmic microwave background radiation. Melchoir 23:07, 19 May 2006 (UTC)

This is an area of disagreement within the physics community, though one with little practical impact. See Mach's principle for one side of the argument: that a local inertial reference frame is determined by the distribution of all matter in the universe. Another way of interpreting it is that Newton's second law is a definition rather than a law: that is, an inertial reference frame is one in which the second law holds. moink 20:28, 19 May 2006 (UTC)

"Disagreement" is the wrong word. There are certain issues where taking one philisophical perspective is most helpful for some problems, and another is helpful for others. -- SCZenz 00:20, 20 May 2006 (UTC)

You may also want to look at Philosophy_of_space_and_time#Absolutism_vs._relationalism moink 20:32, 19 May 2006 (UTC)

Fish out of water?

Can a fish out of water see? The refractive index of water is about 1.33 and air is about 0. That means the image shall form in front of the retina and the fish shall suffer from myopia.

How does an amphibian animal deal with this problem? -- Toytoy 09:59, 19 May 2006 (UTC)

The refractive index of air is about 1, not 0. Arbitrary username 20:42, 19 May 2006 (UTC)

I don't know about you, but I can see under water. Henry^Flower 10:15, 19 May 2006 (UTC)

Perhaps you mean to ask, "can a fish out of water pass an eye exam?" Which of course introduces a myriad of other problems. You are correct when you say that the eye's function in water vs in air is dramatically different and there are none (that I am aware of) that are suited well for both. I have heard of animals that posess a sub-eyelid that acts as a sort of contact lens to adjust the eye to underwater vision. I thought it was the Penguin, but a skim of that article doesn't turn up any clues. --Jmeden2000 14:31, 19 May 2006 (UTC)

The unique divided eyes of anablepidae, or 'four-eyed fishes', can see above and below the water line at the same time. Femto 14:56, 19 May 2006 (UTC)

The feature I mentioned is a Nictitating membrane, but it doesn't seem like many would suggest it functions to improve vision, but more as protection for the cornea.

"How does an amphibian animal deal with this problem?" You might be interested in this famous paper: "What the Frog's Eye Tells the Frog's Brain". Lettvin, JY, Maturana, HR, McCulloch, WS, & Pitts, WH (1959) Proceedings of the IRE, Vol. 47, No. 11 online --GangofOne 22:53, 19 May 2006 (UTC)

A flying fish has a flat cornea, so that in air it does not focus light. A normal convex cornea of course does not do this under water - nor does the flat one. Many fish focus by moving their spherical lens forwards and backwards. What do amphibians do? Dunno. Most of human focus occurs at the air/cornea interface, so that the lens does not have much to do. --Seejyb 22:03, 20 May 2006 (UTC)

a drop from 3.5 km

if I jump of a plain at a height of 3.5 km. with how many speed do i fall down?

Just one at a time. Cthulhu.mythos 10:49, 19 May 2006 (UTC)

As an alternative, you might have a look at Air resistance before doing your homework. Cthulhu.mythos 10:50, 19 May 2006 (UTC)

Or read terminal velocity. Conscious 11:07, 19 May 2006 (UTC)

The question looks very much like a homework problem. As stated, there is not enough information in the question to provide an accurate answer. For example, the drag coefficient of your body, which depends on its geometry, is not known. Maybe the question makes a simplifying assumption that air resistance has little or no effect. If that's the case, the question reduces to one of energy conversion (from gravitational potential energy to kinetic energy). --68.238.243.228 12:47, 19 May 2006 (UTC)

Jumping from a Plain at a height of 3.5 km would be quite a feat! Even the Great Plains are great only for their horizontal dimension, vertically they are quite uninteresting.

A giant was drunk enough to fall his entire height which was 3.5 km. Did it hurt ? Ex-plain and give the proper calculations. --DLL 19:25, 19 May 2006 (UTC)

Make it so that the answer is terminal velocity of the object. -- Mac Davis] ⌇☢ ญƛ. 07:20, 20 May 2006 (UTC)

Very roughly -- something about 60m/s (Here speed's limited with air resistance. Would you fall from height of 1km, 3 km or 8km, your speed would be about 60m/s. Conversely, if you'll fall from heights of about 5 m or 30 m, your velocity will be nearly the same as if there were no air). However, air resistance wouldn't allow you to remain alive after such fall... ellol 01:27, 23 May 2006 (UTC)

microeconomics-pricing in a competitive market

In a competitive market, the firm's price equals the minimum average total cost (ATC)How? If the marginal revenue is greater than the marginal cost, profit will increase, and vice versa. So if the MR is greater than the MC in a competitive market, why is the profit maximising level when they are equal? Dont you need the marginal revenue to be bigger than the marginal cost in order to make profit? — Preceding unsigned comment added by 192.115.60.109 (talk) 08:21, 19 May 2006 (UTC)

Congratulations on taking an entry-level economics course! You will not find a lot of success here in getting people to do very basic assignments. Our minds cloud over at the horrible memory of when we actually did our own homework, long ago. --Zeizmic 13:37, 19 May 2006 (UTC)

This is easiest to explain with calculus, but I'll refrain because I don't know if you know calculus, so here it goes: Profit equals revenue minus cost. The quantity of output at which the difference between revenue and cost is GREATEST (i.e. greatest profit) is the quantity at which marginal revenue and marginal cost are equal (if you know calculus, marginal revenue is the first derivative, or the slope, of the graph of revenue versus quantity output, and marginal cost is the slope of the graph of cost versus quantity output. Keep in mind that MARGINAL REVENUE DOES NOT EQUAL REVENUE, and the same for cost, because they are different things). J. Finkelstein 16:31, 19 May 2006 (UTC)

And take a look at the graphs at the article Profit maximization. J. Finkelstein 16:37, 19 May 2006 (UTC)

There, some people are very nice and have helped you with your homework (a little bit). In general, companies hate this, and whine about Commodification in their business. --Zeizmic 17:17, 19 May 2006 (UTC)

It's Sheep We're Up Against: keeping mutton as a lawnmower

Hi all,

I'm currently inquiring into the legality of this with town council, but it may be okay, so I figured I'd do some preliminary research: how much lawn would I need to have ... actually, let me broaden the question: what are the practical considerations when looking into having a sheep as an outdoor pet to act as a lawnmower during the summer months, and having it slaughtered in the fall for winter mutton? I have a double lot, which means about 1200 feet of grazing area. Breaking this down into sub-questions: How much land is necessary to sustain a single sheep? Are sheep okay solo, or do they get bored/depressed/weird if they don't have companionship? What are the medical requirements of having a sheep... cost for a vet visit, etc.? How much does a full-grown sheep weigh? I have a very large outdoor shed that's practically unused, so the plan would be to buy a little sheep, convert the shed into a barn area, fence in the whole property, and let the sheep live and graze all summer; in the fall, pay a slaughterhouse to "convert" it into meat. Is this a practical idea, or a fool's paradise? --MattShepherd 17:17, 19 May 2006 (UTC)

Ah, I grew up with the creatures. In my country, in moderate climate, as a very rough basic start for ordinary range meat sheep, 1 per 15000 to 22000 sq ft. That is, you should then not need additional feed. But type of grass/pasture, rotation and watering etc modifies that greatly. Farmers in the area could help you there. If you wish to keep the sheep on your lawn only, you are going to have to become a grass farmer, with maybe two paddocks, or accept that you would need to buy feed, and let the sheep keep the lawn closely cropped as a sort of fresh delicacy. For adult sheep you are looking at weights of 90kg to 180kg (200 to 400lb), unless you go for miniatures.

A sheep is ok solo, but you are going to become her/his friend. But then, of the small breed sheep like Southdowns you could put two on your grazing. I'd get a small breed, plan on feeding, but wouldn't plan on eating it! Like I wouldn't eat my dog or pet pig. It just gets that way. At the house that myself and a few friends rented while students, we had the bright idea of obtaining two ducks for snail control, and eventually a Christmas meal. Well, when that meal came out of the oven, no-one had an appetite, while a passing beggar had a windfall.

The vet issue stumps me, one obviously can't buy farmer-size bottles of medication as one would for 1000 sheep, so you would probably be taking your friend in to the vet's twice a year, and getting yourself a book on the signs of sheep well-being and illness. All in all, I think it would be a rewarding undertaking, and a wonderful learning experience. The best place to look for advice is from a local farmer, especially if your vet can recommend one. If you then buy one of his sheep, you may be able to return it if your undertaking turns out to be non-sustainable. --Seejyb 21:31, 19 May 2006 (UTC)

I'm no expert on sheep but I recently took a small night course on raising them. It was offered through the local university as an extended learning sort of thing where just anyone could sign up for the course whether they were students at the time or not. Course the university is well known for its agriculture studies, so if you live near MIT or some other mainly tech/business school, you may not have the same luck in finding such a course. But you could look into that and maybe learn more than you ever thought you'd learn about sheep in just a few nights. Dismas|^(talk) 01:24, 20 May 2006 (UTC)

How much land is necessary to sustain a single sheep? I once had a pet sheep that operated quite nicely on a 1/8 acre section (that's about 20 x 25 m). It all depends on the type of land you've got though, since this affects the stocking rate. Are sheep okay solo, or do they get bored/depressed/weird if they don't have companionship? Sheep are weird even with companions. They do get a bit bored, but as long as they've got something to keep them interested (my one seemed to like the odd old cardboard box). They also appreciate human comany every now and again, so going out to pet it is recommended. In other words, treat it like a pet, not like a lawn mower. How much does a full-grown sheep weigh? they can be lifted if you're strong, but they are fairly heavy, especially when they have a full fleece. At an estimate I'd say 100 lb (45 kg). You've got an apt name, BTW! :) Grutness...wha? 05:30, 20 May 2006 (UTC)

Also keep in mind that there will be lots of sheep dropping on your lawn, which can be unpleasant when you want to use it for recreational purposes (i.e. lazily lying around in the sun). You will also have to shear the sheep from time to time, as common sheep have been bred to grow a thick fleece. There may still be other races without the excessive buildup, though. --212.202.184.238 14:43, 20 May 2006 (UTC)

Those would be hair sheep breeds. Rmhermen 20:20, 21 May 2006 (UTC)

I was playing with it and it fell off? a little help

I was rubbing it the other day and for no reason at all it just fell off? I didn't think i was rubbing it that hard, will it be ok? I heard from a couple of my friends that it's perfectly normal, and that it's supposed to fall off? even that it's able to grow back. I kind of miss it, and wish it hadn't fallen off, will I be less of a person for going through life without it? Will not having it affect my masculinity at all? will i not want to eat meat anymore? how long does it take to grow back? can it be reattached? or is the area too sensitive for that kind of surgury? I mean I have extras, and from now on I'll never rub it so hard again. But still, I liked the one I had--Question asker 18:05, 19 May 2006 (UTC)

Dude, some of us are trying to ask serious questions about using sheep to mow our lawns here. I hear your style of dazzling wit is in high demand over at SomethingAwful, though. Go spread your genius there! --MattShepherd 18:21, 19 May 2006 (UTC)

I understand this is most likely to happen with really small ones.

IANAMD. Do not fret so much, it is quite normal at age 7 (however, if yours now fell out a bit early, there is still a good chance you may grow up normal) A new one will grow out, called an "adult" one. And this may continue for a few years still, eventually culminating in so-called "wisdom". But that needn't worry you now, if this was just a front one, you're still miles away from the wisdom stage. Until all the "adults" have grown out, you may have a problem with mastication. --Seejyb 22:15, 19 May 2006 (UTC).

Why is Foam White

I searched online, however was unable to locate any references. I was standing on my balcony overlooking the Thames and it is a muddy river with constant boat traffic. My question is this... why is the foam so incredibly white, both at the bow and stern? --Djymz 18:27, 19 May 2006 (UTC)

Some ideas... Foam isn't a good food for bacteria, mold, fungus - so none of that will flourish on the foam. Foam left in the sun bleaches easily. Foam is fragile, so the dirty outside is easy to chip off and expose the clean inside. --Kainaw ^(talk) 18:35, 19 May 2006 (UTC)

I think the questioner was refering to foamy water caused by a boat, not foam like styrofoam. --Chapuisat 18:47, 19 May 2006 (UTC)

And to try to suggest an answer, foamy water is full of tiny bubbles and this changes it from fairly transparent very reflective because the surface of these bubbles reflect the light. See Whitewater --Chapuisat 18:52, 19 May 2006 (UTC)

A soap bubble has colors because the light reflects off the inside and outside surfaces and interferes with itself constructively or destructively depending on its wavelength. Foam is many tiny bubbles oriented randomly, so the colors average out to make white light. Put another way, a ray of light that hits the foam is scattered in a random direction which doesn't correlate with its wavelength because the bubbles have random thicknesses. —Keenan Pepper 05:57, 20 May 2006 (UTC)

Perhaps foam is white for the same reason that clouds are white? Mist is white too. -- Mac Davis] ⌇☢ ญƛ. 07:19, 20 May 2006 (UTC)

Sounds right. The eye is too far away from the bubbles or the clouds to notice the individual colors, so we can only see the combined light.  freshgavinΓΛĿЌ  13:11, 20 May 2006 (UTC)

Advances in computer science

What would a programming language have to do to be truly new? I mean to truly do something which no other language had done before? Is this limited by what computer chips themselves can do? What I'm getting at is that it seems to me that comparisons between languages are comparisons between how they do things and how easily they do things (as well as things like which paradigm(s) they allow / encourage, what type system they use etc etc), not between what they actually can do.

Thanks --87.194.20.253 18:51, 19 May 2006 (UTC)

You may want to take a look at the series of articles: Theory of computation, Computability theory (computer science), Computational complexity theory, and Turing machine. EricR 19:05, 19 May 2006 (UTC)

I imagine a language where you could just tell the computer what you want to do, and it would figure out how to do it. For example, if you told it to solve the quadratic equation:

$ax^{2}+bx+c=0\,$

using the quadratic formula:

$x={\frac {-b\pm {\sqrt {b^{2}-4ac}}}{2a}}$

it would then ask the user for values a, b, and c, and handle the cases of no solution, one solution, two solutions, and imaginary solutions, without the programmer having to specifically code for each of those cases. It would also know how to avoid the potential division by zero error and print out the results automatically. StuRat 19:30, 19 May 2006 (UTC)

If you take Mathematica or Maple as "programming languages", then they can do this sort of thing, even though they're not very new. --Borbrav 20:47, 19 May 2006 (UTC)

"What would a programming language have to do to be truly new?" That's like asking What would a piece of art have to be like to be truly new? If we knew ahead of time, it wouldn't be truly new. Let your mind explode, and then write it; we're waiting. --GangofOne 22:33, 19 May 2006 (UTC)

"Is this limited by what computer chips themselves can do?" - No! Any mathematical question can be reformulated and programmed into a Turing complete programming language, almost by defition. Programming language development today centers around "productivity" - sure, you can write anything C/C++, but do you really want to spend all that time coding it in C/C++ when you can do it in {Java/Python/Perl/Ruby/etc} in a fraction the time? More specifically, programming for parallel computers (multi-processor, or multi-core machines) is *HARD* and the software tool simply don't exist (I should know this very well since I'm doing my PhD in parallel computing). Raul654 22:40, 19 May 2006 (UTC)

I consider quantum programming languages to be new, but they aren't going to run natively anytime soon. Melchoir 22:58, 19 May 2006 (UTC)

New doesn't always imply "good" or "beneficial". I think the better aim is to create something useful, not something new for newness sake. Dysprosia 02:14, 21 May 2006 (UTC)

LPG vs petrol

hi, everything i've read about LPG tells me that for running cars LPG is more economical, less polluting and is generally better for cars than petrol. in these days of global warming and i guess, "energy security" ( as i understand it, which i may not, gas, at least in Europe, comes from Russia) why don't governments promote it more heavily? at least in fuel-taxed societies, if the government increased taxes to pay for converting peoples cars, surely it would cut carbon emmissions over night? basically, i guess i'm actually asking, are there any cons to LPG that i don't know about? thanks 87.194.20.253 18:58, 19 May 2006 (UTC)

It still comes from russia, and it still burns to form carbon compounds. Due to the explosive nature of the fuel, containers have to be very thick and sturdy, in order to cut out all risk of a puncture. Philc _T^E_C^I 19:08, 19 May 2006 (UTC)

LPG is currently cheaper, but it is supply and demand; less people want the product, so it is cheaper. If enough people want it, the price will go up and match other energy sources. The hope of early adopters is that it will stay unpopular long enough for them to profit. Notinasnaid 19:12, 19 May 2006 (UTC)

It's not just about price, it's also about freedom. In the USA about 25 years ago I know that gas stations were forbidden to sell LPG by their franchise owner. IE if they offered LPG they couldn't buy gasoline from them. (It would undercut the gasoline business.) There weren't many LPG cars, but some. Some people converted their trucks and so forth. But here we have a case where a "free market" is subverted by the resource owners to maximize profit, not to maximize consumer demand. If LPG had been commonly available over the recent decades, other benefits would have included less dependence on the usual gang of foreign sources, that we are now fighting over, plus whatever hybrid technical delevopment that may have occurred, plus more choice for the individual. --GangofOne 22:27, 19 May 2006 (UTC)

There are also other disadvantages. Most cars are not originally sold as LPG, and if you make convert a car to LPG the gas tank will occupy much space from the trunk. Also, LPG is currently available at fewer gas stations than petrol, at least here. – b_jonas 09:28, 20 May 2006 (UTC)

And because of the danger of explosions (as mentioned by PhilC), many underground car parks, ferrys etc either ban or restrict LPG-powered vehicles. Check the laws in your area about this. — QuantumEleven 11:51, 22 May 2006 (UTC)

Around here (Rio de Janeiro) there is a lot of converted natural gas vehicles (which can run on both natural gas and gasoline, so there's no problem if there's no station nearby), because the natural gas is much cheaper than both gasoline and alcohol. While it's not LPG, it's a similar situation. --cesarb 12:29, 22 May 2006 (UTC)

getting a head start

hi, all the chat about evolution got me thinking (in a lateral sort of way), it's widely assumed (at least by me) that bi-lingual children, regardless of what languages they speak , are better at learning new languages than monolingual children becuase their concept of language is more refined from an earlier age (e.g. a french/english child would have an easier time learning arabic say, than someone from a monolingual background). is this the same for any other subject areas? if i teach my child long division at the age of three, will he go on to find nuclear science a walk in the park? or how about if i get him started on shakespeare, will he then go on to have mastery of the english language beyond his years? if not, what is it that makes language so special and, if so, aren't we shooting ourselves in the foot by starting school at the ripe old age of 5?87.194.20.253 19:14, 19 May 2006 (UTC)

Teaching as much as possible early on has advantages, but if you overdo it and make the child hate school and learning, this strategy may backfire completely. Learning a language as a way to communicate with friends or family members who speak that language doesn't seem like work, so isn't as likely to cause a backlash from the child. StuRat 19:23, 19 May 2006 (UTC)

It isn't facts that helps. For example, my white trash brother-in-law tried to impress me because his son at age 5 could count to ten using the names of the Nascar drivers in place of the actual numbers. However, he couldn't count to ten with actual numbers. So, knowing the Nascar drivers by number order isn't going to help him in any way in the future. However, if he had learned the foundation of how numbers relate to one another, how the basic math operators work with those numbers, and then how everything in the world relates to numbers... he would have a good headstart when all the other kids are still memorizing their addition tables. I have found over and over that it is the foundation of basic knowledge that sets the "smart" kids apart from the rest. In high school, I was dumbfounded when a classmate tried to tell me tha a tree was an insect because it wasn't an animal. Her foundation of separating plants from animals was never formed so she was destined to fail just about any biology class. --Kainaw ^(talk) 20:23, 19 May 2006 (UTC)

If you read Feynman's various memoirs you find that he doesn't mention his father drilling him on physics facts, but rather nature walks he took where he and his father discussed why various plants and animals did what they did. I believe he even mentions how a childhood friend scoffed at him because he didn't know the names of any of the local birds. Feynman points out that although his friend knew all their names, he didn't actually know anything else about them. Anyways, further anecdotal evidence that developing reasoning capabilities as a child is more important than learning sets of facts. — Laura Scudder ☎ 21:09, 19 May 2006 (UTC)

Read to the kid. All book knowledge comes through having language skills. Makes it clear that books are important. But only interesting ones--don't force it. Even better than books is actually DOING something. But early SCHOOL is a killer. One to one learning about relevant concepts, that seems the thing. (But what do I know?) --GangofOne 22:13, 19 May 2006 (UTC)

No. Cognitive development needs time to run its course. A three-year-old will never understand long division on any level, and atempting to teach it would be, as the educators say, "developmentally inappropriate". You could do serious harm by pushing such things too soon. As for why language develops sooner than abstract thought, well, that's a research question. Melchoir 22:52, 19 May 2006 (UTC)

That's not true, when you hold back abstract concepts from young children, all you do is teach them that understanding isn't as important as structure and memorization. There's no practical reason that you couldn't teach biophysical chemistry to a 3 year old, other than that such a child will be teased mercilessly every second of their life from their first day of elementry school all the way through grad school--71.249.0.202 23:20, 19 May 2006 (UTC)

Three-year-olds can't even understand that when you take ten marbles, toss them in the air, and let them settle, you still have ten marbles. Not even if you do it in front of their faces a hundred times; they'll just become distressed. Biophysical chemistry?! Forget it. And if by some perverse miracle you got a three-year-old to be able to pantomime long division, that would be memorization, because there's no way the poor child understands what's going on. Melchoir 23:32, 19 May 2006 (UTC)

Honestly, most students seem to lose interest in what they're doing by the time they're in thier late teens anyway, that's why 90% of the people in, let's say, a biophysical chemistry lecture, are sitting there with their eyes glazed over nodding their heads alot. Say what you want, but I think the 3 year old is more likely to show interest in it--71.249.0.202 23:38, 19 May 2006 (UTC)

Oh, absolutely, they'll show interest if you present the material in an age-appropriate fashion. I'm not sure what that is... they might have the motor skills by that time to manipulate ball-and-stick models, but they'd also try to eat them. Maybe they'd be amused by some safe chemical reaction that changes color? Melchoir 23:50, 19 May 2006 (UTC)

This all seems to presuppose that a 3 or 4 year old can't be a formal operational thinker, I can't really see why this would be the case, assuming you gave a toddler a crash course in calculus, matrix algebra, simple hermitian operators, and a little bit of inorganic chemistry, you could get through most of that before the child is even in 1st grade, assuming you started the instant they were capable of abstract reasoning, of course that child would probably have a nervous breakdown before it ever entered its teens--71.249.0.202 00:18, 20 May 2006 (UTC)

How absurd. Do you have experimental evidence of concrete operational 3 or 4 year olds that you're holding back from the scientific community? Melchoir 02:46, 20 May 2006 (UTC)

I don't see why no 3-year-old would ever be able to perfrm long-division. It's possible that they would have to record it in a special way, as they might have difficulty with the motor skills required to write it, but it's really a few simple operations repeated over and over. I think it could be done. Getting them to understand why they're doing what they are doing might be harder, but probably achievable. I was always annoyed with people who said children couldn't learn certain types of maths and things until a set age. For example, they refused to introduce us to negative numbers for ages, as apparently children can't understand them until a certain age. However I, along with a few others, was happily using them from the age of about 6, ever since we heard people talking about them. Multiplying and dividing with them was harder, because nobody would tell us properly about them for ages. The main problem I had as a child wasn't the inability to understand certain types of thing, but a lack of built-up experience that left me guessing what 'soda water' and 'rouge' might be in the experiments I read about. Without a knowledge of times tables, I couldn't perform harder maths quickly. I'm not sayig children should be intensively taught these rote-learning things, just that it always felt like the main difference between ages. Skittle 12:23, 20 May 2006 (UTC)

Yes, and no. It's quite possible to be ready for negative numbers at the age of six, assuming more basic operations and properties (like the commutative property of addition, and addition itself in the first place) are already understood. I have a pet peeve of my own in that area: people I trusted in math areas have been telling me for my entire life that division by zero is, plain and simple, impossible. In fact, it's meaningless. And yet, for two years now, I've been using limit notation to do exactly that without fear or hesitation. I could have learned at least the basics of limit manipulation, in fact, right after learning Algebra in middle school. However, there quite simply are limits to what the brain can handle at very, very early ages, like 3 years. It's not just motor operations, it's mental operations as well. I don't know whether long division is one of the things most 3-year-old couldn't handle, but I wouldn't be surprised if it was. Black Carrot 18:54, 20 May 2006 (UTC)

do neutrinos have mass?

elaborate please--71.249.0.202 20:55, 19 May 2006 (UTC)

See neutrino. — Laura Scudder ☎ 21:00, 19 May 2006 (UTC)

See title ^ I was hoping for more of a discussion though--71.249.0.202 21:02, 19 May 2006 (UTC)

I just thought that the article discussed it more thoroughly than we could. — Laura Scudder ☎ 21:10, 19 May 2006 (UTC)

Ok, let's try something more philosophical, a neutrino has angular momentum, which classically implies mass... but doesn't have to--71.249.0.202 23:27, 19 May 2006 (UTC)

Photons have angular momentum but no mass. -- SCZenz 23:37, 19 May 2006 (UTC)

That's why I said classically, not quantum mechanically, and I still seem to be failing at actually starting an interesting discussion about fermions--71.249.0.202 23:40, 19 May 2006 (UTC)

This isn't a discussion board. It turns into one, sometimes, but a good question usually helps jump-start things. Yes, neutrinos have mass. This is observed due to neutrino oscillations, and the Seesaw mechanism may be involved. What else would you like to know? -- SCZenz 00:16, 20 May 2006 (UTC)

Is this homework? ?_? --KJ 01:22, 20 May 2006 (UTC)

What sort of homework would that be?--4.236.165.94 02:15, 20 May 2006 (UTC)

Debate? --KJ

Hahah. Neutrinos have mass. Period. Ooops I just put three periods. :P That was an excessively lame joke... -- Mac Davis] ⌇☢ ญƛ. 07:17, 20 May 2006 (UTC)

Time

I've looked in time and not found anything relating to the question "Is time continuous or is it formed of discrete quanta". Any pointers to anything discussing this? -- SGBailey 21:33, 19 May 2006 (UTC)

I can't offer anything but I really want to know what the possible interpretations (I won't say answers) are too. Could I extend the question to cover matter and space too? Sorry to butt in without anything to offer but I think the whole thing's really interesting - you know, whether the concept of discrete quanta as you put it has any basis in reality or not. The way I see it, possible interpretations would have great potential bearing on the philosophy of science and maths - we go around counting things all day but are there really any things that would justify the abstraction? Thanks. --87.194.20.253 21:39, 19 May 2006 (UTC)

Time is continuous, the only things that are discrete are the things you can count. Like apples. yum yum. Philc _T^E_C^I 22:00, 19 May 2006 (UTC)

Says who? You would be equally able to state that matter is continuous, not discrete, but then someone discovered atoms. I doubt we could (ever?) count discrete time - if such is - as it is probably quantised at some tiny level like 10^-30 second. -- SGBailey 22:06, 19 May 2006 (UTC)

Isn't time, more specifically the second, defined in the precise terms of the harmonics of a cesium atom? Last I heard, cesium is a discrete unit, and since you're measuring the emmesions of said atom, you're measuring a photon, a discrete quanta if I've ever seen one--71.249.0.202 22:42, 19 May 2006 (UTC)

No, Our unit of time is defined that way, but that says nothing about the nature of time. The metre used to be defined as the length of a rod in Paris - that says nothing abiout the existance or otherwise of atoms. -- SGBailey 23:15, 19 May 2006 (UTC)

Well that's the problem, time isn't something you can measure directly or otherwise, you can only measure a process that's supposed to occur over the course of time, but that's a bit of a circular definition--71.249.0.202 23:23, 19 May 2006 (UTC)

I didn't say matter was continuous I said apples where, if you have two apples, even if you count to a million decimal places, you still have two apples or to be precise, 2.00000000000000000.... Philc _T^E_C^I 07:44, 20 May 2006 (UTC)

Most of what I've heard is that we wouldn't be able to measure units of time smaller than the Planck time, so we wouldn't be able to distinguish continuous time from discrete time of that quanta. There's also a Planck length. — Laura Scudder ☎ 22:13, 19 May 2006 (UTC)

I 'kind-of' like the concept of quantised time - it suggests that, in combination with quantised space, we could live in a giant 4-D array - The Matrix like. (I'm not saying this is how things are...) -- SGBailey 23:15, 19 May 2006 (UTC)

To answer the original question, you may like to read this discussion between philosophers and physicists on physicsforums [3]. -- Mac Davis] ⌇☢ ญƛ. 07:12, 20 May 2006 (UTC)

Yes, there is considerable speculation that space and time may be quantized at a tiny subatomic level. I don't have the issue with me, but a recent issue of Scientific American] had an article discussing this. I would not be surprise were it to be so. Perhaps there is nothing continuous in nature, nothing analog—the universe really may be digital. — Knowledge Seeker দ 08:09, 22 May 2006 (UTC)

roving a sheave block

I have 3 pulley blocks: 1x single, 1x dbl, 1x triple. The multiple blocks are sheaved side by side. What is the correct way to rove (run the rope through) the blocks to avoid them twisting? I am seeking a mechanical advantage of 6:1 for lifting. PS - The single pulley will be the tail out as it has a ratchet. Regards -JAG.

Soda losing fizz!

This has annoyed me for quite some time now, so I am going to ask here. A friend of mine says that leaving a bottle of soda without the cap on will not reduce the amount of fizz in the bottle faster than if one was to screw/unscrew the cap every time one needed to refill. Have there been any studies on soda losing fizz? It is an economical issue, actually. Today I was going to the store with some bottles, and found that there was half a gallon in total of unfizzy soda left in the "empty" bottles. You CAN'T drink unfizzy soda, it's like torture of some kind. The only good thing about soda losing fizz is that it becomes something to clean the pipes with, albeit not very efficiently. Henning 22:46, 19 May 2006 (UTC)

Your friend is mistaken. While the bottle of soda is under pressure, carbon dioxide gas – the 'fizz' – is forced to remain dissolved in the soda. (The pressure in the bottle actually comes from a small amount of the dissolved carbon dioxide accumulating in the headspace of the bottle between the top of the liquid and the cap.) When you open the cap, that carbon dioxide (CO₂) gas escapes, and fresh CO₂ is free to come out of solution. That CO₂ will continue to come out as bubbles as long as the soda is open to the air.

Putting the cap back on the bottle allows CO₂ gas to build up in the bottle once again. Once it reaches a sufficiently high pressure, it will hold the remaining CO₂ in solution in the soda and preserve your remaining 'fizz'. The more times you open and close the soda, the less CO₂ will remain—but it's still better than just letting the CO₂ escape continuously. TenOfAllTrades(talk) 00:37, 20 May 2006 (UTC)

Also (and this is one of my great pet peeves) do *not* squeeze the bottle when you put the cap on. If you do, the CO2 in the soda will escape and re-fill the half-crushed bottle, thus causing the soda to go even more flat. Raul654 00:52, 20 May 2006 (UTC)

Ah, great! Thanks to both :) I will now venture forth in life with good knowledge of flattening soda. Henning 10:51, 20 May 2006 (UTC)

Unless the bottle is going to be shaken, in which case squeezing the bottle will minimise the ratteling which causes faster release of the fizz. The squeezing also makes sense if the bottle will be forced to keep that shape. I was taught the squeezing trick on a hiking trip where a squeezed bottle was then tied to the rucksack with a strap -- which makes it both easy to access and saves the fizz. --Swift 00:24, 21 May 2006 (UTC)

May 20

What phase of matter is a Frosty?

I need something to reply to that "soquid" nonsense. Is it a gel or an emulsion or what? —Keenan Pepper 01:34, 20 May 2006 (UTC)

Seems to me it's a liquid, with a high viscosity. -- Filliam H Muffman 02:28, 20 May 2006 (UTC)

The definition of a solid is that it retains it's shape whereas a liquid takes the shape of the container it is in. Even if refrigerated, a frosty will take the shape of its container (albeit slowly - as Muffman said, indicative of high viscosity). Thus, it is a liquid. Raul654 02:31, 20 May 2006 (UTC)

Don't be ridiculous. The Frosty is either: A) solid ice crystals in liquid flavoring or B) liquid flavoring in a solid...er...thing. I vote for "A", which would make it a sol, like paint. Not "sol" as in the other name for the sun, but "sol" as a colloid with solids mixed into a liquid. --M1ss1ontomars2k4 | T | C | @ 05:25, 20 May 2006 (UTC)

Sand will take the shape of the container it's in, but I don't see any claims that sand is a liquid. Notinasnaid 08:00, 20 May 2006 (UTC)

A single grain of sand is solid and will not take the shape of its container. For the same reason, a single steel ball-bearing is solid, but a ton of them poured into a swimming poll will take the shape of the pool. Raul654 08:04, 20 May 2006 (UTC)

I don't think that's relevant about sand not being a liquid. I think it isn't a liquid because even though it will take the shape of the container, that's only the bottom surface of the sand. The top surface might not be flat, but can form a cone or any shape that isn't too steep. As an analogy, put a large pile of chlotes (to be ironed) into a basket, and push it down somewhat. They will take the shape of the basket, that is, there won't be large gaps between the wall of the basket and the chlotes, but the top surface of the chlotes won't be flat. On the other hand, the surface of a liquid will always become flat and horizontal. – b_jonas 20:04, 21 May 2006 (UTC)

So, to demonstrate that a frosty is a liquid, you would have to first demonstrate that it is a single solid object rather than a collection of them. It seems easier to explain that the frosty is a loosely bound collection of solids (with some liquids acting as a binder). Notinasnaid 08:07, 20 May 2006 (UTC)

Guys, don't be silly. Everybody knows its a colloid—it is composed of more than one state of matter, and cannot be said to be any one phase. It is composed of crystals of different shapes, sizes, and constipates, bubbles, and liquids (from the melted crystals), suspended in a liquid. Asking what state of matter is a frosty is comparable to asking what state of matter is a pizza, without offense, you know. -- Mac Davis] ⌇☢ ญƛ. 07:04, 20 May 2006 (UTC)

Yeah, colloid, that sounds right. Much better than "soquid" anyway. —Keenan Pepper 08:21, 20 May 2006 (UTC)

I thought it was an interesting commericial. Boy are frosties good. The local Wendy's's frosty machine is broken :( -- Mac Davis] ⌇☢ ญƛ. 08:46, 20 May 2006 (UTC)

Are you certain it's a colloid? If you've seen the add, it seems like the ice crystals at least are way, way to big to fit within the range mentioned in that article, and it certainly isn't at all comparable to mayonaise and fog. Black Carrot 19:02, 20 May 2006 (UTC)

A good frosty doesn't have ice crystals big enough to see or feel. It's as smooth as mayonnaise. —Keenan Pepper 20:05, 20 May 2006 (UTC)

What would it be if it did? Black Carrot 21:59, 20 May 2006 (UTC)

It would probably still be colloid because no matter how big the crystals are, there's a good amount of water and syrup sticking them all together.  freshgavinΓΛĿЌ  11:33, 23 May 2006 (UTC)

Its an OIW (oil in water emulsion), and due to the solid state of the milk fat, a colloid. Technically its also a foam because it contains air bubbles. The "water" of the OIW is actually a mixture of water, ice, sugar, and (possibly) whatever else is in a frosty (otherwise they're dissolved in the fat). --Eh-Steve

See? See? I told you it was a colloid! A sol is a kind of colloid!

Domestication question

Okay, I've actually gotten into a discussion about this with some people and I want to ask it here: Do you think it would be possible to domesticate a giraffe? I mean, obviously it would be an outdoor animal --but I think they might be quite fun as pets or at the least an alternative farm animal like ostriches. Same for sea otters, although I don't think they'd be as easy to take care of (and I have no interest in eating them) --sure you could place them in a pool but the chlorine would probably not mix well --would they require a base amount of salinity? They're sooo cute! Okay, the first question is serious, not the one about otters. The latter just rock. -- Bobak 02:10, 20 May 2006 (UTC)

• Far as I can tell, river otters can be domesticated (see Ring of Bright Water if you want some lessons as to why you might not want to make a pet of one), but not sea otters -- you'd need something of an ocean, a lifetime supply of abalones, and one hell of a lot of kelp! Dunno about giraffes, but I did find a picture of someone named Jimbo riding one. I think the giraffe was stuffed, though. --jpgordon∇∆∇∆ 02:32, 20 May 2006 (UTC)
• Otters can be tame if they grow up in captivity. This is different from domestication, as they have not been bred to be this way, they're just raised by humans and are less wild. For example, at Wellington Zoo they have a small-clawed otter which is highly "domestic" as he was raised by humans (he was the runt of the litter and wouldn't have survived otherwise), meanwhile his brother has very different behaviour, having been raised by his mother, and he doesn't respond to humans the same way.

Back to the main question. Yes, I'm sure giraffes could be domesticated over many generations just like horses (a not too distant relative) have been. As for keeping them as pets, I'm sure you already could, if you had the space, just like zoos do. —Pengo 03:29, 20 May 2006 (UTC)

Do zoos count as really large backyards, the zookeepers the "owners" of sorts", and the animals "pets"? OK that was weird question, but I'd like to know what others think. --M1ss1ontomars2k4 | T | C | @ 05:22, 20 May 2006 (UTC)

In a word, no. People generally keep pets for companionship or for a practical function (such as cats to control rodent populations). Zoos keep animals for conservation, education, and entertainment, but not for companionship for the keepers (who are paid staff) or for a practical function. Also, almost all zoo animals are not domesticated. In other words, even if they are tame, they are still genetically wild animals identical to their relatives not in captivity. Truly domesticated animals such as dogs and livestock are different from their wild relatives, usually to the point they are considered different species. --Ginkgo100 21:12, 20 May 2006 (UTC)

There are giraffe preserves in which giraffes are more-or-less tamed/domesticated/conditioned to be used to humans. The most famous is probably "Giraffe Manor", founded by Betty Leslie-Melville, the Giraffe Lady, near Nairobi in the 1970s to preserve the Rothschild Giraffe. The giraffes poke their headsd through the second-story windows to "have breakfast" with the guests there. - Nunh-huh 05:39, 20 May 2006 (UTC)

Wow! Thanks for all the feedback. I really thought otters weren't going to work, but I guess they could too. Just reading the Wikipedia synopsis of Ring of Bright Water was depressing... I think I'll pass on it (sounds like the Old Yeller of otter movies). I remember seeing otters similar to the small-clawed otters at the Osaka Aquarium Kaiyukan (they were small and freshwater), I guess those would be possible. I guess I'll have to be a millionaire some day to raise them, though. As for giraffes, thanks for all the suggestions as well. Thanks for the reference to the Giraffe Lady, very interesting stuff! -- Bobak 19:26, 20 May 2006 (UTC)

Jared Diamond has some theories on the un-domesticatibility of most animals. See Guns, Germs and Steel. Rmhermen 20:11, 21 May 2006 (UTC)

As Pengo says Domestication of wild animals is different from taming them, compared to the former the latter is relatively easy. It is unlikely that there are any wild species which are now capable of domestication but haven't already been at least partially domesticated. AllanHainey 14:28, 22 May 2006 (UTC)

Viruses, etc

what is the difference between bacteriophages, viruses and retroviruses — Preceding unsigned comment added by 211.28.236.104 (talk)

Answers taken from the opening paragraph of the articles:

bacteriophages

A bacteriophage is a virus that infects bacteria.

viruses

A virus is a submicroscopic parasitic particle that infects cells in biological organisms.

retroviruses

A retrovirus is a virus which has a genome consisting of two RNA molecules, which may or may not be identical. It relies on the enzyme reverse transcriptase to perform the reverse transcription of its genome from RNA into DNA, which can then be integrated into the host's genome with an integrase enzyme.

—Pengo 03:22, 20 May 2006 (UTC)

Note that bacteriophages and retroviruses are all kinds of viruses. --M1ss1ontomars2k4 | T | C | @ 05:18, 20 May 2006 (UTC)

The Speed of Time

I've heard of a saying in physics that "time travels at the speed of light".What does it mean by that?

In Einsteinian physics, it is impossible for information (i.e. causal influence) to travel faster than the speed of light. Time and causal influence are closely related concepts; events that are causally connected (i.e. one is in the other's future time cone) are said to have a timelike separation. Thus causal influence -- "time" -- expands through space at the speed of light. -- EdC 06:51, 20 May 2006 (UTC)

The speed of time can only be said as going at one second per second. 1s/s. One second elapses each second. This is, of course quite silly, because speed is change in position over time. Time is not a physical concrete thing, and cannot change in position. -- Mac Davis] ⌇☢ ญƛ. 07:01, 20 May 2006 (UTC)

I beg to differ. Claiming that something travels doesn't necessarily imply it's a concrete matter-based substance; forces (like gravity) travel without manifesting physically. If you drive your warp-drive mustang to the convenience store, you're going to send out ripples in space-time at the speed of light, which is unfortunate because to travel as fast as they do in the TV show you're going to need to be sending out ripples quite a bit faster.  freshgavinΓΛĿЌ  12:51, 20 May 2006 (UTC)

Cockroaches

Are cockroaches known to cannibalise within their species or other species? -Tim Rhymeless (Er...let's shimmy) 06:29, 20 May 2006 (UTC)

How would a cockroach cannibalise anything that isn't a cockroach? Just being picky... Howard Train 06:19, 21 May 2006 (UTC)

Yes. I thought this was mentioned in the cockroach article, but it's apparently not. Do a google search for "cockroach cannibalism" and dozens of references turn up. While we're talking cockroaches, I'd never thought I'd feel sympathy for the things but this is the most evil thing I've ever heard of. If I didn't know better you'd almost count it as evidence for a malevolent deity...--Robert Merkel 08:18, 20 May 2006 (UTC)

Or as evidence towards creationism. How the hell do you evolve skills like that??  freshgavinΓΛĿЌ  12:38, 20 May 2006 (UTC)

Feel sympathy do you? Well that's your empathy talking. Cockroaches don't even feel pain. Sure, I'd be bad if it happened to you, but you have feelings and can think. -- Mac Davis] ⌇☢ ญƛ. 08:44, 20 May 2006 (UTC)

What makes you say they don't feel pain? I can't imagine a scientific test for this. —Pengo 09:09, 20 May 2006 (UTC)

Moral values are not absolute concepts, thus a discussion about what is evil and what is not, simply referring to "mystically produced" empathic feelings is absurd by definition. When it applies to the behaviour of animals it's even more ridiculous. This seems to be the cause of powerful predators (whatever methods they use) seen as evil and a possible cause for moral vegetarianism and veganism. --GTubio 10:45, 20 May 2006 (UTC)

Trouble with DRM

I've recently bought an Aigo A208-1G MP3 player. It is supposed to support DRM 9, but I downloaded the sample track from tesco but it wouldn't play - on my computer it made windows media player crash and on my mp3 it doesn't appear in the list of music (this is what happens to non-music files). Do you think it is the file, or my system that is the problem? Is there anywhere I can download a different drm 9 test from?--Bjwebb (talk) 10:49, 20 May 2006 (UTC)

Oh, I've just realised, it does appear in the list on my MP3 player, it just doesn't play - it skips to the next song.

I've managed to fix the problem by reinstalling media player and using it to transfer the file to my mp3, along with the license.--Bjwebb (talk) 13:10, 20 May 2006 (UTC)

Ratiocination in Evolution

On 19 May 2006, Rush Limbaugh said, "If the closest relatives of humans are chimpanzees, then why do they still exist?"

What is the best argument to counter such a query? I am very much baffled in light of the fact that humans and chimpanzees have inhabited the same regions throughout history.Patchouli 10:54, 20 May 2006 (UTC)

Unless we eradicate all other living things from the earth, we'll always have a closest relative. But in the case of the chimpanzees and other great apes, it's important to remember we didn't evolve from them, but instead share a common ancestor. Somewhere we split up, and both continued to evolve from that point on, taking on their own niche, with it's own habitat and food sources. How much those overlapped in the past i won't dare to guess. While the DNA match is high, humans and chimps really are quite different animals in many ways. SanderJK 11:27, 20 May 2006 (UTC)

I wasn't aware that there was any proof of human involvement in the disappearance of our other close ancestors. By that I mean that I don't believe we have proven homo sapiens caused the downfall of any of its close relatives, and so I don't see why anyone would assume that they would do the same to chimpanzees.  freshgavinΓΛĿЌ  11:33, 20 May 2006 (UTC)

As the chimpanzee article says; Biologists believe that the two species of chimpanzees are the closest *living* evolutionary relatives to humans. So, by definition, they still exist, and Limbaugh's question is a circular argument. The fossil record shows other species (both within and outside of genus homo) that were much closer in evolutionary terms to homo sapiens than chimpanzees, but they are now extinct - an example is Australopithecus. Gandalf61 11:41, 20 May 2006 (UTC)

Simply put, chimpanzees are our relatives, not our ancestors. They are better described as our distant cousins than as our grandparents. —Pengo 13:42, 20 May 2006 (UTC)

• Thank you.Patchouli 19:36, 20 May 2006 (UTC)

I'm not sure I understand the argument either. There's no reason to think someone's ancestor automatically can't coexist with their decendants. --BluePlatypus 22:19, 20 May 2006 (UTC)

If cakes are made out of eggs, why do we still have eggs? Skittle 22:51, 20 May 2006 (UTC)
good analogy.Patchouli 11:37, 21 May 2006 (UTC)

Because cakes cant have sex to make baby cakes, eggs don't grow into cakes, cakes did not evolve from eggs, eggs are essential to making every single cake, not just one initial master caker. Poor analogy, on so many levels. Philc _T^E_C^I 17:07, 21 May 2006 (UTC)

But it wasn't meant to be an analogy for the entire process of evolution; that would clearly be stupid. The purpose of an analogy is to take an aspect and simplify it to be more easily understood, not to be accurate. It was merely making the point that not all 'monkeys', 'chimpanzees', or whatever form the silly slogan is taking today evolved into humans. Of course, we all know that the argument is flawed on so many levels. Humans did not evolve from monkeys or modern apes, etc. But even if you make the assumption that they mean 'non-human primates' in general when they say 'monkeys'/'apes'/'chimpanzees', the cake analogy explains in an instinctive manner that just because something comes from something else, doesn't mean all the original thing has gone. If cakes evolved from eggs, it wouldn't be an analogy at all. I don't know what you expected :-\ And I don't know why it's orange. Skittle 22:03, 21 May 2006 (UTC)

• I arbitrarily chose orange to make it stand out. I think it is an analogy because it is simplification to ease comprehension which need not be accurate in every facet.Patchouli 23:52, 21 May 2006 (UTC)

But as pointed out, it's a false analogy, and even if Rush understands it he still would have not been informed that he's been caught deliberately mischaracterizing evolution. The takeaway lesson for someone who asks such a question should be "I don't know enough about evolution to talk about it in public, I'd better read something so I don't embarrass myself again like that in the future". We're not dealing with someone who has a habit of letting facts get in the way of his opinions..... - Nunh-huh 04:46, 22 May 2006 (UTC)

• I think Rush Limbaugh was knowingly and purposely using the query to mischaracterize evolution; he bent the facts in the Terry Shiavo case.Patchouli 13:29, 22 May 2006 (UTC)

Of course he was. You could easily fill a book with all the mischaracterizations, misleading statements, factual errors, self-contradictions and outright lies Rush has spouted over the years. Several such books have even been written. On the other hand, Rush isn't in the business of pursuading people through rational arguments, weighing pros and cons against each other from a premise to reach a conclusion. Rush is in the business of entertaining his listeners by reaffirming their existing views with amusing rhetoric and personality. He's quite brilliant at that. --BluePlatypus 06:35, 24 May 2006 (UTC)

If my closest relative is my brother, why does he still exist? Gdr 12:42, 24 May 2006 (UTC)

Fears of a protein famine

I remember reading about this in the 1980s (and our Quorn article mentions it too) - apparently the "big thinkers" decided in the 1950s that the world was headed for a global shortage of dietary protein (presumbaly due to some kind of cow shortage). Motivated by this, lots of folks tried producing protein from novel sources. I remember reading about some large organisation trying to produce protein by growing something (bacteria?) in an unwanted heavy fraction of mineral oil, only to be thwarted by the excessive levels of uric acid found in DNA and RNA (a problem solved by the makers of Quorn). Do we have an article about this supposed protein shortage, and about those novel alternative sources projects? It'd be a fascinating read. -- Finlay McWalter | Talk 13:39, 20 May 2006 (UTC)

Oh, I did find this (PDF). -- Finlay McWalter | Talk 13:42, 20 May 2006 (UTC)

"Unable To Deliver Document. Sorry. We are currently unable to deliver your document. The delivery URL has expired" Could you provide a reference to the paper you found? Cheers! Dr Zak 00:43, 21 May 2006 (UTC)

Global Warming

What percentage of global warmingis caused by polution from transport?

I think our article on Global warming has some information on the percentage increases in carbon dioxide gas emissions in recent times. It's a comprehensive article, so you may find the information in there that you want. -- Daverocks (talk) 14:32, 20 May 2006 (UTC)

#wikipedia-science plug

I've recently kicked off a science related chat room, which readers and writers on the Science reference desk may be interested in:

#wikipedia-science on freenode.net.

Come along and ask a question or join the discussion on #wikipedia-science. All welcome. —Pengo 13:59, 20 May 2006 (UTC) </plug>

I've always wanted one of these. Some of the discussions on this ref desk are great and it would be much enhanced as a live chat :) -- Daverocks (talk) 14:16, 20 May 2006 (UTC)

I tried to follow the link, but it didn't work. Is there something special I have to do? Black Carrot 21:59, 20 May 2006 (UTC)

Yes, the link points to an IRC channel. Since following the link didn't work, your browser doesn't understand what to do with a URI that begins with irc://. You will need to open the channel in your IRC client (see: List of IRC clients), direct your broser to send all IRC protocols to the client or get a broser that has an internal IRC client (Opera does). --Swift 00:41, 21 May 2006 (UTC)

SDS-PAGE electrophoresis

I analyze protein solutions with an electrophoresis system from Amersham called "PhastGel" (I've heard other people refer to them as 'mini-gels'). I'm not a molecular biologist and I just use this system because it is what was already available in my lab.

I never see 'real' molecular biologists use this type of system for electrophoresis. I'm pretty sure that this simple-to-use system has some weaknesses, but I don't know what they are. Basically I want to get an idea of what I am sacrificing by using this type of system, versus the type of system used by more sophisticated workers. ike9898 14:21, 20 May 2006 (UTC)

This article, http://www.pubmedcentral.gov/picrender.fcgi?artid=175959&blobtype=pdf lists some disadvantages on the PhastGel system. Mike _{(T C)} 15:50, 20 May 2006 (UTC)

Number of moles?

I need to determine the number of moles I used in a titration.

The gfm of NaOH is 40, and I used 38mL of it. Do I take 40 times 38...?

Please help! Thanks in advance!

You need to know the concentration (or "molarity") of the NaOH solution. The molar mass and the volume are not enough information. —Keenan Pepper 19:47, 20 May 2006 (UTC)

It is a .25M solution of NaOH.

That means each liter of the solution contains 0.25 moles of NaOH. You know how many liters you used, so you can easily figure out how many moles that is. —Keenan Pepper 22:10, 20 May 2006 (UTC)

Old radio "Bands"

I've checked the articel here on radio spectrum but can't seem to find an explanation for this: I found an old radio (vacuum tubes, etc) with different "bands" marked on the tuning dial (Weather, Foreign, Police and AM), but except for the "AM" dial (Which is written the same as it is now), I can't figure out what the other bands frequencies are, given their markings of things like "6.5" for the foreign on. Anyone with old radio info know what these bands corresponded to? Thanx. 68.39.174.238 19:11, 20 May 2006 (UTC)

They are most likely shortwave bands. The "6.5" is probably in MHz. Dysprosia 02:12, 21 May 2006 (UTC)

Have a look at [4]. If that doesn't give you all the information you wanted to know about shortwave receivers...--G N Frykman 19:55, 21 May 2006 (UTC)

Radio+Bath=???

This is partly inspired by the discussion above involving birds and power lines. I've heard all my life, from very reliable sources, that if you drop an electrical appliance into a bathtub while it's plugged in, and someone's in the tub, they'll be killed or seriously injured. How? Tap water is (if I'm not mistaken) almost infinitely less resistant of current than the human body, so according to my physics class, almost no current should pass through them. Besides, it would have to travel quite a bit out of its way to even reach them, if I'm understanding the circuit correctly: (one wire->resistant appliance of some kind->other wire) becomes (one wire->barely resistant water right next to it->other wire). Black Carrot 19:21, 20 May 2006 (UTC)

Pure water is a pretty good insulator. Salt water, and water with other kinds of impurities in it, is a pretty good conductor. Tap water tends to have impurities in it, many of which decompose into ions: see hard water. Also, person + water = somewhat salty water. moink 19:49, 20 May 2006 (UTC)

I'm not sure I buy that. There's still no reason a significant current would flow through you instead of the radio. —Keenan Pepper 20:03, 20 May 2006 (UTC)

I'm aware distilled water (which is expensive to get in sufficient quantities to fill a bathtub on a regular basis) doesn't conduct at all well. I'm also aware, from my AP Chemistry class, that it's the free-floating ions in the water that carry the actual current, by moving away from one wire and towards the other. That's why I figured it ("it" being the tap water, which is certain to be quite conductive in this sense) would be carrying the current in the first place. BTW, since you mention it, I can't help doubting that even the most foully sweaty person could possibly make a tubful of water strongly conductive on their own. It starts out that way. Black Carrot 21:02, 20 May 2006 (UTC)

Surely from the point where the live wire enters the water it can go two directions, or split and follow both: 1. back through the neutral wire to earth, or 2. through the large mass of water and human to earth. Which way it goes, and the split of the current depends on the relative resistance of the parallel paths. That depends surely on what is dissolved in the water, the temperature of the water, the connection between the bath and ground, and the resistance of the neutral return wire. Since people do get electrocuted this way, conditions favouring conduction through the water do occur, and it would be a brave or foolish person who trusts his life on the purity of his tap water, and adequately low resistence in the neutral return wire. Wet skin has a much lower resistance than dry skin. --Seejyb 22:57, 20 May 2006 (UTC)

From AP Chem, I learned that DI water doesn't do anything, but even the slightest trace of ions (like in tap water) will conduct electricity. --M1ss1ontomars2k4 ^{(T | C | @)} 04:01, 25 May 2006 (UTC)

When I first saw this post I thought, "That sounds like something the MythBusters should test," and then I wondered if they already had. Sure enough, here it is. (It was confirmed, for those of you who don't want to follow the wikilink.) EWS23 | (Leave me a message!) 07:11, 21 May 2006 (UTC)

Equation Balancing?

Can someone explain to me how to balance this equation in a double replacement reaction?

NaOH + C₆H₈O₇ = ?

It depends on the structure of the organic reactant, but one of the products is probably water. Balance it by making the number of atoms of each element the same on either side. —Keenan Pepper 19:39, 20 May 2006 (UTC)

So would it be NaOH + C₆H₈O₇ = C₆OH + NaH₈O₇? I haven't started on the numbers yet but is that being correctly replaced so far?

No, because C₆H₈O₇ isn't an ionic compound of C₆ and H₈O₇. It's citric acid, so it'll give up three hydrogen ions and leave a citrate. —Zero Gravitas 21:09, 20 May 2006 (UTC)

So it'd be more like NaOH + C₆H₈O₇ = H₃OH + C₆H₅O₇ something like that?

Be careful, you can't just eliminate the sodium. A hydroxide ion would bond with one hydrogen to form water. The sodium cations would bond with the citrate to give sodium citrate, so the unbalanced equation is:

NaOH + C₆H₈O₇ = Na₃C₆H₅O₇ + H₂O

The rest is just stoichiometry. A balanced equation doesn't necessarily have to start with one of each reactant... —Zero Gravitas 21:53, 20 May 2006 (UTC)

So the balanced equation is 3NaOH + C₆H₈O₇ = Na₃C₆H₅O₇ + 3H₂O

Is that right?

Yep, looks right to me. —Zero Gravitas 04:04, 21 May 2006 (UTC)

Specific heat of Hydrogen Plasma

I read that the specific heat of hyprogen gas goes up with temperature. When it gets hot enough for the hydrogen to change into plasma does this tren in rising specific heat continue, or is there a whole diferent ball park estimate for a "relitivly" low temperature plasma specific heat. I think I read some thing about the specific heat changing due to the diassosation of H2 into H1 so maybe this levels off, no?

This is a really good question and I'm surprised no one has answered it yet. I know it has to do with the number of degrees of freedom, which should be higher for the plasma than for the monatomic gas (I think...), but I can't say how that will affect the specific heat. I haven't even taken thermodynamics yet! Could someone knowledgeable please answer this question? —Keenan Pepper 19:14, 22 May 2006 (UTC)

I don't know about $\partial c/\partial T$ (the "trend"), but the specific heat for the plasma should be higher than for the gas because there's more particles to heat (the dissociated hydrogen, then later (hotter) the protons and electrons separately, although the plasma will not in general be completely ionized). If this is the only effect, then the specific heat would increase forever as the last little bits of the gas ionized. But there are probably other factors eventually. --Tardis 21:20, 22 May 2006 (UTC)

CD-RWs

How do rewriteable CDs work? I assume that recordable ones simply laser away the unwanted material, leaving behind the correct sequence of pits and bumps. But rewriteable ones must be able to create bumps also. How do they do this? Daniel (‽) 19:28, 20 May 2006 (UTC)

The article CD-RW says how they work. What in particular do you want explained? —Keenan Pepper 19:34, 20 May 2006 (UTC)

volcanos

i may not know excalty what causes volcanos to erupt. but i understand that the pressure builds up to a a point where it cant be contained anymore. so heers my idea, why not manulay release the pressure every so often so the pressure cant build up to a destructive point. ie by say drilling into the volcano away from populated areas?--Colsmeghead 21:19, 20 May 2006 (UTC)

Well, there are a few reasons for why not. First, you would have to drill DEEP. The further away from populated areas you want the vent, the deeper. Imagine the lava/magma/whatever the heck inside the earth's crust, a few kilometers down or so (see volcano for that, I don't remember the distance. It only rises in a rather steep "/\" depending on where you are. That means, it isn't realistic at all to even start thinking about drilling. Drilling is also not a good idea because if you want to drill far down and close to the magma, it gets hot. If it gets hot, things can be dangerous, and your tools could very well melt away. In most cases, I think it's much more economic and realistic to just move people out of the way, ALTERNATIVELY creating lava shafts and routes, leading any eruption away from populated areas. Then there are those cities that are very close to big ones (see Vesuvio). It's a good idea, but in the end it can't be done with today's technology. Henning 23:18, 20 May 2006 (UTC)

well i didnt mean down into the earth but rather into the mountianside--Colsmeghead 10:27, 21 May 2006 (UTC)

Let's imagine that there is no magma in a volcano until it begins to erupt, only cold lava, ashes, &c. Magma people live very deep. --DLL 17:39, 21 May 2006 (UTC)

Every volcano lies somewhere between two extremes. At one end are volcanos whose magma is very fluid (e.g. Hawaii); it easily flows out the top and rolls down the sides. The only real danger with that kind of volcano is being right in the path of the lava, and since it doesn't move very fast, this is rarely a problem. The other extreme are volcanos with magma that is very viscous and solidifies as soon as it reaches air. This means that wherever it reaches the surface the magma freezes and creates a plug that prevents more magma from flowing. However, the magma behind it keeps trying to move forward dispite this obstruction. This causes pressure behind it to build and eventually the blockage ruptures and the volcano erupts in a large explosion. This is the kind of volcano that tends to be very destructive. You couldn't effectively release this pressure by drilling because as soon as you got past one obstruction you'd find that the magma behind it would solidify and create a new obstruction. In practice, the only way for large quantities of material to get out of a volcano like this is for it to be moving so quickly that it doesn't have time to solidify; in other words, such volcanos require explosive eruptions to dissipate magma. The difference between these two kinds of volcanos is based primarily on the chemical composition of their magmas, so there isn't much you can do with an explosive volcano to make it tamer. Dragons flight 18:26, 21 May 2006 (UTC)

Even though we can't do it, this seems to be a popular science fiction idea. You might have read The Little Prince by Antoine de Saint-Exupéry, in which the Little Prince explains how he cleans his volcanos every day so that they burn with a steady flame, but that the volcanos on the earth are too large to do this. Another novel is A Földrengések Szigete by Fehér Klára, in which the heroes actually drill a hole in a mountain to avoid a great catastrophe. (Sorry for any spoilers.) – b_jonas 19:30, 21 May 2006 (UTC)

botany:physiology of bacteria

the study of bacteria bacteriology --Seejyb 23:06, 20 May 2006 (UTC)

NaHCO3, water and an acid

One of the oldest ones from science class. NaHCO3 in water turns into Na+ and HCO3-. Add an acid, and the HCO3 reacts with the H+ in the acid. AFAIK, pH means percent of Hydrogen ions, ie H+. The question is simple: Will the reaction become more violent the higher pH my acid has? Henning 23:11, 20 May 2006 (UTC)

Yes. —Keenan Pepper 00:38, 21 May 2006 (UTC)

Nit: pH isn't the percent of hydrogen ions, it's -log [H⁺]. --David Iberri (talk) 03:35, 21 May 2006 (UTC)

You've both fallen for a very old trick. The reaction will become more violent the lower the pH. And I do believe that the "p" of pH originated from the German for percentage. G N Frykman 08:51, 21 May 2006 (UTC)

No it did not. See pH. --Heron 09:26, 21 May 2006 (UTC)

Now I am utterly confused. The acid becomes more alkaline the higher the pH. I have seen alkaline metals react with water, and they seem to react violently enough. So untill Frykman gives reason to his claim, I'm going to go with the answer that Keenan was the first to give. :) Thanks! Henning 10:51, 21 May 2006 (UTC)

In the reaction between sodium hydrogencarbonate and a dilute acid, the sodium ions do absolutely nothing. It bears no relation to the reaction between alkali metals and water. The more H+ ions there are per unit volume, the faster will be the reaction between them and the hydrogencarbonate ions (giving carbon dioxide and water). The pH scale is slightly odd in that the lower the number, the greater the concentration of H+ ions. I said that you had fallen for an old trick - in many exams, the question is asked - which has a higher pH, a strong acid or a weak acid? And the answer is the weak acid. In a similar way, a weak alkali has a lower pH than a strong alkali. To summarise - a low pH indicates lots of H+ ions which will give a fast reaction with sodium hydrogencarbonate. G N Frykman 11:38, 21 May 2006 (UTC)

Thanks, that does make a bit of sense. So, a pH of 6 indicates a WEAK acid, a pH of 2 is a STRONG(er) acid? Similar, a pH of 8 is a WEAK alkali, a pH of 12 is a STRONG(er) alkali? A WEAK alkali interacts more violently with the H+ than a strong alkali, and a STRONG acid interacts more violently than both a weak acid, a weak alkali and a strong alkali? Henning 16:16, 21 May 2006 (UTC)

In determining whether an acid is strong or weak, it's more important to look at pKa than pH in solution (pKa is constant for a given acid, while pH varies depending on the acid's concentration). Clarifying your first statement, an acid whose pKa is 2 is stronger than an acid whose pKa is 6. pKb is a similar dissociation constant used to indicate the strength of bases: a base whose pKb is 8 is stronger than a base whose pKb is 12. --David Iberri (talk) 17:17, 21 May 2006 (UTC)

Spot on, Henning! But you're not likely to notice much difference comparing the reactions of a strong acid and a weak acid just in the basic neutralisation reaction (acid + base) except that weak acids produce a marginally smaller temperature rise. Where it does become obvious is in the reactions of acids in which a gas is given off, and they are: acid + metal (eg magnesium); acid + carbonate (eg calcium carbonate) and the one you started with, acid + hydrogencarbonate. In all of these the speed of fizzing is dramatically slower with weaker acids, such as ethanoic acid, compared with the typical strong acid, hydrochloric acid. David Iberri - I was trying to keep it simple. Direct comparisons of pH can be made as long as the acids are of equal concentration. G N Frykman 17:25, 21 May 2006 (UTC)

IANAC (Chemist). Referring to the original question: I thought the rate of a reaction depends on the activity of both substances, in this case H⁺ and HCO₃^-. In other words, I'd expect the rate to be limited by either the amount of HCO₃^- or the amount of H⁺. Decreasing the pH (increasing the H⁺ activity) would normally increase the reaction rate, until the reaction goes as fast as the HCO₃^- concentration allows. Then increasing the H⁺ beyond that (decreasing the pH) would not give a more violent reaction. Or am I wrong, does the concentration of NaHCO₃ not influence the rate?

What "p" stands for: the pH article gives a number of "explanations", but as I read the original paper, Sörenson didn't state precisely why he chose "P", except that he wrote "10¯P". See the extract from S.P.L. Enzyme Studies II. The Measurement and Meaning of Hydrogen Ion Concentration in Enzymatic Processes. Biochemische Zeitschrift, 21, 131-200 (1909): "The value of the hydrogen ion concentration will accordingly be expressed by the hydrogen ion based on the normality factor of the solution used, and this factor will have the form of a negative power of 10. . . . CP . . means the number of gram atoms of hydrogen ions per liter, is less than 1 in all cases treated in this paper and can thus be placed equal to 10¯P. For the number P, I have chosen the name "hydrogen ion exponent" and the written expression PH." It would be strange if Sörenson would choose "P" to refer to a percentage, when he is writing about the negative of a Power (German: Potenz) to the base 10 of a number. --Seejyb 17:50, 21 May 2006 (UTC)

I think this reaction is first-order in both H⁺ and HCO₃^-, which means the rate is proportional to the product of their concentrations, so the rate wouldn't be limited by either one. That's a total guess though. P.S. Sorry for not reading the question through the first time. Obviously the reaction is stronger with stronger acid, which corresponds to lower pH. =P —Keenan Pepper 19:09, 22 May 2006 (UTC)

May 21

Server Park

what is the definition of a computer "server park"?—The preceding unsigned comment was added by 12.164.252.227 (talk • contribs) .

Isn't a server park the same as a Server_farm? --Swift 00:57, 21 May 2006 (UTC)

It sounds like the place the servers in a server farm would go on their day off. However, while Google has 1.7 million hits on "server farm" it also has 28 thousand for "server park". This page appears to use both interchangeably [5]. Coming soon: "server sweatshop". Notinasnaid 11:27, 22 May 2006 (UTC)

Eat my hair

Since hair is protein, can you eat it, and would it be nutritious? Also, what is the best way of cooking it? Im serious! 8-)--Light current 00:44, 21 May 2006 (UTC)

I remember hearing a story about a girl who would eat her hair, and accumulated a large hairball in her stomach. It's called trichophagia. Seems like you shouldn't do it. Dysprosia 02:10, 21 May 2006 (UTC)

And the resultant product is a "hairball", or if you're not a cat, a "trichobezoar". Keratin is basically insoluble, so there's no way for you to digest it. - Nunh-huh 07:29, 21 May 2006 (UTC)

So you would need to convert it into something soluble- then you could eat it?--Light current 12:17, 21 May 2006 (UTC)

That 'fur' enough! 8-)) Perhaps it needs preparing in a proper manner.--Light current 03:23, 21 May 2006 (UTC)

I propose you the following scheme: cut your hair off, burn it, then use the ash to fertilize cucumbers. ellol 06:11, 21 May 2006 (UTC)

• You can eat hair, but your body won't digest it. However, blood can be eaten and digested.Patchouli 11:33, 21 May 2006 (UTC)

Even though you can't digest it as is, Cannibalism#Modern cannibalism claims that there are edible products made from human hair. – b_jonas 19:16, 21 May 2006 (UTC)

I have trichotillomania! Kilo-Lima|^(talk) 19:44, 21 May 2006 (UTC)

OK. Well I guess Id better clear the larder of all those hanks!--Light current 19:47, 21 May 2006 (UTC)

Papain digests keratin - hair and nails. Eventually you'll have a soft soggy mess. Whether the result is edible I know not, nor do I wish to, I think. --Seejyb 23:20, 21 May 2006 (UTC)

Cortical Arousal

Can you explain cortical arousal? Especially as it pertains to hypnosis?

Cortical arousal is controlled in large part by the reticular activating system (RAS), a network of centers in the brainstem that regulate how effectively cortical neurons respond to stimuli. During arousal, two centers in the RAS, the locus coeruleus and raphe nuclei, bathe the brain in norepinephrine and serotonin, respectively, increasing the effectiveness with which neurons of the cortex respond to stimuli. I'm not sure how hypnosis fits into that picture, but I suspect it has to do with habituation to a persistent stimulus. --David Iberri (talk) 03:31, 21 May 2006 (UTC)

Acetic Acid

I'm doing highschool chemistry and I need to know what the chemical formula for acetic acid is to balance an equation. The wikipedia article says it's CH₃COOH. I don't think that's what I'm looking for. Can someone help me out here? Thanks.

That indeed is acetic acid's chemical formula. What makes you think it's not what you're looking for? --David Iberri (talk) 03:20, 21 May 2006 (UTC)

Well there's more than one of each C,H, and O. Shouldn't it be something like C₂H₄O₂? Or something like that?

That's the molecular formula. CH₃COOH is a "condensed structural formula" which also gives you some idea how the atoms are connected. —Keenan Pepper 04:26, 21 May 2006 (UTC)\

(After edit conflict)

You're right that there are more than one atom each of C, H, and O in acetic acid, but the molecular formula C₂H₄O₂ isn't the only way to represent that. The formula CH₃COOH conveys the exact same information: in CH₃COOH, you count two Cs, four Hs, and two Os, making it equivalent to CH₃COOH. The benefit of the latter formula is that it gives you clues about the structure of the molecule represented. In particular, COOH is the common representation for a carboxylic acid functional group, while CH₃ is the common representation for a methyl group. So from glancing at CH₃COOH, one can reasonably guess the structure of the molecule. The C₂H₄O₂ formula provides no such structural clues (aside from what can be gathered by calculating degrees of unsaturation) and is therefore ambiguous: does C₂H₄O₂ refer to acetic acid or to its isomer ethen-1,2-diol? --David Iberri (talk) 04:48, 21 May 2006 (UTC)

I...have no idea, actually. I'm in highschool chemistry and am currently doing titration. So C₂H₄O₂ actually does work? I really just need it to balance an equation. Thank you for the feedback BTW

Yes, C₂H₄O₂ is fine. — TheKMan^talk 05:01, 21 May 2006 (UTC)

It's fine for stoichiometric purposes (balancing an reaction). But since it's ambiguous with respect to what the compound *is* (as David says) it's not a very useful way of writing the reaction, because you don't know what the reaction is - which is usually the main point of writing the thing up to begin with. --BluePlatypus 06:59, 21 May 2006 (UTC)

Whether you condense it further from CH3COOH is up to you and really depends on the application you're talking about. If you use CH3COOH it's clearly an acid, but if you say C2H4O2 there's ambiguity, as BluePlatypus said. --M1ss1ontomars2k4 | T | C | @ 23:45, 21 May 2006 (UTC)

Charge of an electron

This IS a homework question, but i am a bit at loss at the answer. 'Given that the charge on an electron is 1.6 * 10^-19 C. which of the following amounts of charge are possible?'

a)6.4 * 10^-19 C

b)5.6 * 10^-19 C

c)6.0 * 10^-6 C

My answer was a, (1.6*4 =6.4). The book says that c is also possible- im not sure how this can be. Please help me (Thanks in advance)

Well, just to make sure we're all on the same page, have you looked closely at the exponents? Melchoir 07:51, 21 May 2006 (UTC)

Sorry, Melchoir, I'll proceed with your thought. If c) is actually 6.0 * 10^-6, you should note that this value is 10^13 times greater than the charge of an electron. To make sure that the value c) is a multiple of 1.6 * 10^-19, you would need at least 13 digits. But you have only two digits, and it means, that the value may actually be in the range from 5.95*10^-6 to 6.044*10^-6. This range covers a great many multiples of charge of the electron. So, of course, c) is possible. ellol 08:31, 21 May 2006 (UTC)

Let me guess, you're an engineer? ;P -- Mac Davis] ⌇☢ ญƛ. 08:42, 21 May 2006 (UTC)

I'm a student who hopes to become a physicist, so you are mistaken here :).

There are no exact numbers in physics(contrary to mathematics) and each value has some error. A physicist must "feel" the values, may be, as well as an engineer. If you wanna become a physicist you'll (besides other things) need to know by heart constants, such as Planck's_constant or charge of the electron, etc, -- in order to be able to make quick estimations. ellol 09:28, 21 May 2006 (UTC)

Ooh, I'm all over that. 1 and −1. Do I get a prize? Melchoir 09:40, 21 May 2006 (UTC)

Theoretical physicists are not considered :-) Yeah, I meant only experimenters. ellol 10:08, 21 May 2006 (UTC)

Electron charge should not be measured in degrees Celsius. -- Mac Davis] ⌇☢ ญƛ. 08:40, 21 May 2006 (UTC)

But it could be measured in coulombs... G N Frykman 09:22, 21 May 2006 (UTC)

Ok thanks all for your help, i understand now.

Electron charge should not be measured in centimeters. — Knowledge Seeker দ 09:24, 21 May 2006 (UTC)

But it may be measured in speeds of light. Howard Train 13:25, 22 May 2006 (UTC)

You have the choice between C and Java. --DLL 17:31, 21 May 2006 (UTC)

Static electricity

When you get a shock of static electricity, the reason is presumably that your body has acquired a surplus or deficit of electrons compared to the environment. How would one go about to estimate the number of electrons that is transferred in such a shock? Does somebody have an idea of the approximate number? When walking on synthetic carpets etc., do we usually acquire a positive or negative charge? --Vibo56 12:24, 21 May 2006 (UTC)

No ,when you get a shock, its because charge has passed through your body causing the muscles to contract. THe amount of current passing depends upon the voltage, the resistance of the static generator, and the body's internal reistance (which is about 700R).

As to charge build up, I would try the Faradays ice pail experiment with the victim standing in the pail. The pail needs to be insulated from earth. THe victim would not actually get a shock because current would not pass thro the body (hopefully). Then by knowing the capacitance of the pail and its final voltage after charge transfer, one can calcualte the amount of charge passed.8-)--Light current 12:36, 21 May 2006 (UTC)

There are some calculations done by Mr Static here. The answer in his case was a positive charge of about 3 x 10^-8 coulombs, which is about 2 x 10¹¹ electrons. --Heron 13:39, 21 May 2006 (UTC)

Thanks a lot, Heron, that was exactly what I was looking for. The value of 3 x 10^-8 coulombs appears to be per step, the graph might suggest a charge buildup about 20 times larger. --Vibo56 13:58, 21 May 2006 (UTC)

Construction of Houses and Apartments

Currently in Iran, homes in cities and towns are built using steel, metal rods, and cement. In the United States, only skyscrapers are built using cement.

Why is it that homes in even major American cities such as Los Angeles are built using wood? Is there an advantage with respect to cost or something else? Can't cement better withstand earthquakes?Patchouli 13:31, 21 May 2006 (UTC)

Properly engineered, a wood construction is very resistant to earthquake damage, and it's much cheaper to build an earthquake-safe construction from timber frame than from masonry. Timber constructions flex enough to avoid damaging themselves, and generally fail gradually; masonry constructions don't flex, and so fail dramatically. Plus timber framed constructions are much lighter, so there's less moving mass that the structure has to absorb. In California houses are (hopefully) bolted to their foundations (to stop the house falling off the slab), walls and roofs are secured together (particularly to prevent the roof falling off, which would squish one side of the house) and walls (particularly in the basement) are braced with sheets of hardboard to prevent a shearing of walls. To properly reinforce a masonry construction to earthquake safe standards requires great amounts of metal and bolting, and often the attention of a structural engineer. The efficacy of this approach is shown by the fatality levels in comparable earthquakes - the 6.9 Loma Prieta earthquake shook the entire San Francisco Bay Area, with most of the regions 8 million people within 70 miles of the epicenter. Yet only 63 people died, and two thirds of them died in when the Cypress Street Viaduct collapsed - so no more than 21 people died in other places. Compare that with the 2003 earthquake in Bam, which at 6.6 was considerably less powerful and struck an area with only a few hundred thousand people - yet 26,271 people died. In San Francisco there are some older masonry buildings which were constructed before current building code was introduced. By law these have large signs outside which read "This is an unreinforced masonry construction: such structures are known to be unsafe during earthquakes". Similarly, during the last quake in Napa, I believe only one person was killed - when the brick fireplace/chimney in his (otherwise timber) house failed, and fell on him. Timber and shingle is a very good material with which to build homes in a quake zone. -- Finlay McWalter | Talk 13:53, 21 May 2006 (UTC)

• First, I conclude that skyscrapers need tremendous attention from structural engineers. Next, I am led to think that in a non-quake zone, it is better to build homes with steel and cement because then they are less prone to catch fire. Regardless of this fact, perhaps timber frames are used in those zones to save money.Patchouli 14:25, 21 May 2006 (UTC)

There's a number of other reasons, although saving money is a good reason to use wood - why would you want to spend more money?

• Home renovation is popular in the United States, and it's much more difficult to modify a concrete structure than a wooden one. Concrete would have to be chipped out, and the rebar cut using steel cutting tools. Designing reinforcement is more difficult than framing carpentry, and creating it again requires the use of welding and steel cutting equipment. It's even more difficult to hang a picture on a concrete structure -- I know because I live in an apartment with outside and between-suite walls of concrete, but internal wooden walls. And guess where my pictures are?
• Formwork is needed for a poured concrete structure; constructing this is specialized, skilled work and requires a lot of -- you guessed it -- wood. So a concrete structure first gets a temporary wooden structure, which is then replaced with concrete. You can see how this is wasteful.
• In the United States, fire fighting and fire prevention is of sufficient quality that flammability simply isn't an important consideration. According to our article on houses, 67% of Americans live in a house, which, given 122 million housing units is roughly 82 million houses. This fascinating report on fire losses in the US says there were 300 thousand house fires in 2004. This sounds like a lot, but it's only 0.37% of the houses. In other words, on average, a house in the US can be expected to have a fire once every 272 years. Furthermore, the average damage is only $16,400 where the median value of a house is $119,600. Assuming the contents of a house are worth 10% of the total value, and assuming a house sustains only very minor damage in a house fire (say $2,000) or is totally destroyed, only 1 out of 9 houses would be totally destroyed.
• Concrete structures can have issues in wet and in particular cold climates. The freeze-thaw cycle can damage concrete, reinforcement can rust, and freezing inhibits the concrete curing process, which means that houses could only be constructed in the summer. Iran obviously has a much warmer temperature than much of the United States.
• Finally, concrete is heavy, and a house built of it usually needs more involved structural engineering than a house made out of wood. Concrete is really not a very good building material -- it's about as strong as uncooked spaghetti. But it's cheap, and we can use a lot of it, and reinforce it with steel to make reinforced concrete, which has some merits. --ByeByeBaby 16:57, 21 May 2006 (UTC)

• These are very good explanations.Patchouli 18:01, 21 May 2006 (UTC)

Also, while uncommon, concrete houses are not unknown in the U.S. Various energy-efficiency designs use concrete construction - thermal mass, earth-sheltered, etc. Some areas with hurricane and tornado risks also have some concrete houses - Habitat for Humanity favors this type of construction. Using interlocking styrofoam forms, which may also preposition the rebar makes this construction much simpler and avoids the issues of building removable wooden forms. This is said to be a fast-growing market in the U.S.[6]. Rmhermen 18:51, 21 May 2006 (UTC)

On the topic that a wooden house is more resistant to earthquakes than a brick house, see also [7]. (By the way, here in Budapest where earthquakes are very rare, there are almost no wooden houses.) – b_jonas 19:10, 21 May 2006 (UTC)

Building wooden houses in Iran would presumably be very expensive, they do not have forests to chop down for timber. All countries outside of the tropics and the world's northern forest zone would have the same problem. The logical building materials would be stone, bricks, and mortar. Only the rich would use reinforced concrete for building a private house, but when governments are involved in housing projects, with architects and engineers all involved, it's use seems logical - low maintainance requirements, durability and fire resistance would be factors favouring concrete over wood. The concrete high-rise structures I have seen being built don't have concrete walls; there is a reinforced concrete "skeleton", floors often made of prestressed beams overlain with a screed; exterior walls of brickwork and interior walls of composite board. What do the European countries make houses of - e.g. Scandinavia vs Spain? In practice, how many storeys high can an all-wood house be? --Seejyb 22:00, 21 May 2006 (UTC)

Well, as you guessed - Spain traditionally uses stone/bricks/adobe, whereas Scandinavia traditionally builds fully-timbered (log-houses) or wooden houses. Once you get down to Denmark and Germany there are less forests and to conserve wood, people built Half-timbered houses. And south of the Alps it's pretty much all non-wood. Modern wooden houses can be pretty high, the highest one (a recent construction) is claimed to be a 5-story building in Trondheim. I've personally seen modern 3-story apartment buildings in Scandinavia which were wood. (You wouldn't think it looking from the outside though). But those are an exception, not the rule. In general modern buildings are of course built in modern materials even in Scandinavia just as everywhere else. --BluePlatypus 23:50, 21 May 2006 (UTC)

Paralysis causes loss of feeling?

Does paralysis cause loss of sense of feeling in the affected limbs? Can a person feel pain, heat, pressure where he is paralysed?

"Doctor, Doctor, I can't feel my legs!" "That's because we've chopped your arms off." Often, but not always; it would depend how the paralysis is caused. Spinal cord trauma will typically interrupt both motor and sensory fibres to the affected areas, but a stroke in the motor cortex might leave sensation undamaged. -- EdC 15:56, 21 May 2006 (UTC)

In other words, paralysis doesn't cause anything. It's the underlying cause of the paralysis that determines whether sensation is affected. One example of paralysis with some sensory sparing is anterior cord syndrome (ack, redlink -- try this), in which only the anterior (front, ventral) portion of the spinal cord is damaged. An oversimplified explanation is that the fibers carrying motor information are located in the anterior region of the spinal cord, while the sensory fibers are carried in the posterior region and are therefore preserved in anterior cord syndrome. Also, since different types of sensory information are carried in different parts of the spinal cord, the type of sensory information affected by an injury depends upon the injury itself. For example, in anterior cord syndrome, typically only fine touch and conscious body sense is preserved, while pain and temperature information is lost. (See dorsal column-medial lemniscus pathway and anterolateral system if you're interested in the details.) Hope that helps, David Iberri (talk) 16:46, 21 May 2006 (UTC)

Perfect, exactly what I was looking for. Thanks for the help! --82.146.104.90 17:29, 21 May 2006 (UTC)

working model related to astronomy

how to make a simple low cost working model of anyhing related to astronomy??

hmmm... Sounds like homework... Philc _T^E_C^I 17:09, 21 May 2006 (UTC)

A disc with a big blob in the middle, and a smaller blob on the outside? Star and planet?--Light current 17:51, 21 May 2006 (UTC)

It shouldn't be that difficult to upgrade that to a basic orrery, depending on the level of education the project is set for. GeeJo ^(t)⁄_(c) • 20:46, 21 May 2006 (UTC)

Quite! But you cant get much simpler than that!--Light current 20:58, 21 May 2006 (UTC)

Yeah. Piece of dark paper and punch some holes in it. Hold it up to the sun and you have a cheap-ass planetarium.  freshgavinΓΛĿЌ  15:37, 22 May 2006 (UTC)

Thats not really a model tho is it? Imean mine can be made to rotate by sticking a pencil thro the centre 8-)--Light current 15:56, 22 May 2006 (UTC)

about svchost.exe

There is a process called svchost.exc in my computer that downloads data when the Internet connection is on even though I am not downloading any file or any website. Is it a virus that has installed in svchost.exe or is it something like - the system itself is downloading essential software from Microsoft? What is that? Is there any thing wrong or is there anything to worry here?

I'm assuming the ".exc" is a typo. Svchost.exe is an integral part of microsoft windows, and there is usually serveral instances running. I believe it can by hijacked by viruses, though. You might check this by turning off automatic Windows updates. If svchost.exe still wants to contact the internet, there might be a problem. --Vibo56 18:12, 21 May 2006 (UTC)

There are web sites that explain various standard Windows processes. The easy way to find those sites is to google for "svchost.exe", here is one: [8].

Whenever I see a process in my task list that I'm not familiar with, I google the filename and the word 'virus', which has so far always given me the information I need. Despite the fact that most of the programs have turned out to be harmless, I find using the word 'virus' in the search is useful because it returns results where other people have asked about the safety of the process. Furthermore, I find that most antivirus sites maintain listings of native operations that might seem suspicious to users. Also, while a great many sites describing standard OS programs are quite detailed (so much so that it's sometimes difficult to figure out whether or not they're safe), I find the antivirus sites' descriptions seem to be quite succinct and easy-to-understand.--Anchoress 07:11, 22 May 2006 (UTC)

In addition, consider that there are viruses and worms which disguise themselves as apparently harmless processes (e.g., "svchosts.exe"). If the name "svchost.exc" is not a typo, chances are you indeed fell on a virus. Cthulhu.mythos 09:37, 22 May 2006 (UTC)

Microsoft's page "explaining" svchost.exe is here. It also mentions a command that can be run to show specifically which services are associated with an instance of svchost.exe. I am currently on a Windows 2000 box, so I can not test this. Also, the page refers specifically to XP Pro, so the command might not exist in XP Home, however the description of the program is still valid.

In any event, you should be sure to (download if necessary and) run some malware detection programs, such as AdAware and Spybot, to check your system. --LarryMac 13:49, 22 May 2006 (UTC)

plasma containment

What is the cheapest way to confine magnetically a cool, by fusion standards, plasma with a temeperature of 100 000 K? This is not for fusion, but needs to be confined magnetically. Thanks. 24.137.78.34 18:44, 21 May 2006 (UTC)

It depends on the scale. Any significantly large quantity of plasma would require the same sort of equipment (a tokamak or stellarator) regardless of the use you're putting the plasma to. I thought I'd recalled reading about an undergrad producing a small-scale reactor for a project and on searching, found this story. I'm not sure about teh temperatures that the plasma reached in the apparatus though. GeeJo ^(t)⁄_(c) • 20:39, 21 May 2006 (UTC)

Thanks alot.24.137.78.34 11:21, 22 May 2006 (UTC)

Cashews

After eating (about 24 hours) nearly two pounds of Cashews in about the same amount of time my lips began to crack and peel in fairly large sections of skin. Is this due to the resin or oil from the Cashew shell still clinging to the meat of the nut or from the salt the Cashews are covered with? -- PCE 18:44, 21 May 2006 (UTC)

IMHO it's the salt--you need to drink some water. But after eating anything that's two pounds' worth you should be drinking water anyway. --M1ss1ontomars2k4 | T | C | @ 23:42, 21 May 2006 (UTC)

Yeah, the salt. --Mac Davis 00:16, 22 May 2006 (UTC)

You should nt eat so many in 24 hrs!--Light current 00:20, 22 May 2006 (UTC)

Your lips and mouth have had an unusual duration of exposure to cashew nuts, so you may be experiencing toxic effects which are not normally seen. Salt may be the culprit, but would you get the same (with extensive skin peeling) from eating peanuts? I think not. So: local allergy? local toxicity? An unprocessed whole cashew nut is pretty toxic, with skin blisters being a major symptom of contact. Peeling or dehusking a cashew is downright dangerous. I have not looked further into this, but the the possible culprits could be: anacardic acid, cardol, urushiol (as you say, the resin or oil). Or something else? The reaction you had it sometimes seen with drugs such as anti-inflammatories - one of the chemicals in the cashew has an effect on similar enzymes. Could inadequate cleaning leave active toxin behind, in small enough amounts not to cause symptoms with normal consumption? All speculation, but to simply write off your experience as salt may not be scientific - though it would suit cashew nut producers to blame the salt. --Seejyb 03:33, 22 May 2006 (UTC)

Really, I don't think it's an allergic or toxic reaction. Cracking and peeling is the normal and usual reaction to dry lips, and salt can do that, as can cold/dry air. It can happen quite fast. --BluePlatypus 04:46, 22 May 2006 (UTC)

The Urushiol that Seeyjb mentions is also found in my old nemesis Poison ivy, so I wouldn't completely discount a slight allergic reaction. --LarryMac 13:36, 22 May 2006 (UTC)

Thanks everyone for your comments. Although I had some hot coffee during the same period my tongue has also become extra sensitive just like that following a mouth full of hot coffee. Furthermore I had a lot of gas and what look to be similar "sheet’s of skin as opposed to mucus as the stool and I'm sure the salt alone could not have been responsible for that. I've had no dizziness or other symptoms associated with poison versus an organic acid or some type of caustic. Thanks again. -- PCE 06:40, 22 May 2006 (UTC)

By the way, if you are thinking about health, you might like to consider that 2 pounds of cashew nuts contains around 5200 calories, probably twice what you need in a day. I derived this from information on the site [The World's Healthiest Foods]. Notinasnaid 10:23, 22 May 2006 (UTC)

World's Oldest Joke: Doctor, Doctor, it hurts when I do this. Doctor: Well, don't do it! --Zeizmic 19:56, 22 May 2006 (UTC)

No response... I think he's dead. - R_Lee_E (talk, contribs) 19:55, 22 May 2006 (UTC)

Not dead - just delayed in my return from the store to purchase the ingredients for my next consumer risk experiment... Macadamia nuts. ---- PCE 23:29, 22 May 2006 (UTC)

You should try one of your experiments with fruit instead. 8*) No avocados though. - R_Lee_E (talk, contribs) 01:37, 23 May 2006 (UTC)

What's wrong with avocados? -- PCE 18:41, 23 May 2006 (UTC)

crosse' s acari how is it possible?

hai i just read about anderw crosse who was a scientist and accidentaly discovered an organism which lives on no substance , imean it consumes no food for its survival and this thing really doesnt use any growth culture and any life supporting media for itself and its birth also is misterious

well thats all i know about this organism and i also have an copy of "sem" scan please help me i really wanna know my mail id: <email removed> (Kilo-Lima|^(talk) 19:48, 21 May 2006 (UTC))

Well, there're always breatharians. GeeJo ^(t)⁄_(c) • 20:21, 21 May 2006 (UTC)

No it is not possible (it'd violate the 2nd law of thermodynamics), Crosse was mistaken. --BluePlatypus 22:44, 21 May 2006 (UTC)

To be fair, Crosse never thought that that was the explanation, instead believing that it was an experimental error (as our article on him points out.) So he wasn't really mistaken, just careless.GeeJo ^(t)⁄_(c) • 03:12, 22 May 2006 (UTC)

It is theoretically possible that given a source of energy (e.g. light) and the ability to dissipate waste heat, that an organism could sustain itself without taking in any additional food (though it would be unable to grow). Some plants and mosses can approximate this for moderate time scales (i.e. weeks), and some bacteria can shut themselves down for millenia, but I'm not sure there are any known organisms that can truly live in a sealed environment indefinitely. As to the experiment in question, I would suggest reading Andrew Crosse as a good place to start. Dragons flight 22:56, 21 May 2006 (UTC)

The illustration at rexresearch.com is a drawing of what the eminent scientists in London saw under their microscope. It is a mite. Nothing new, and no great mystery. How they got there could possibly be explained if someone was patient enough to reconstruct the experimental scenario. They could have been inside the "stone" or "cloth" he used in his experiment, or quite possibly fell off his head or clothes as he was examining his contraption. They are hardy little fellows, and feed, inter alia, on dust and bits of old skin. Apparently Mary Shelley was in the audience when Crosse gave his presentation, so that the electrically animated mites may have given us a more entertaining story than Crosse's --Seejyb 23:54, 21 May 2006 (UTC)

Odontodes

Just created a page odontodes, left a message on my talk page asking for someone to 'check' it and got directed here (see User talk:HappyVR). As I mentioned there I'm not a biologist and hence not entirely confident in my abilities to write such a page - I've done it anyway. I've also got three references that might be useful for citation (they're on my user page User:HappyVR). I doubt this is the sort of thing that gets looked at very often so I thought I should get it checked to prevent someone being misinformed if I've made a mistake... Thanks.HappyVR 22:08, 21 May 2006 (UTC)

Thanks for being bold and creating this stub! I touched on it a little, adding two of your refs, and will do more when I have time. I changd the name to odontode because article titles should generally be singular. I also tagged it with {{biology-stub}}. It would fit developmental biology, evolutionary biology, or anatomy, but I decided to go general. --Ginkgo100 22:59, 21 May 2006 (UTC)

1/3 meter

The following was moved from Talk:Main Page. - dcljr (talk)

Is there anything that is 1/3 of a meter, which would be the equivalent of a foot?

No. Such things don't exist. BrokenSegue 22:12, 21 May 2006 (UTC)

The whole point of the metric system is that everything is in powers of ten. Having "1/3 of a meter" would defeat the purpose of the meric system. —Cuiviénen^T|C, Sunday, 21 May 2006 @ 23:15 UTC

Actually, 1/3 of a metre is about 13 inches, and that's more than and not equivalent of a foot. --199.71.174.100 04:42, 22 May 2006 (UTC)

The question seemed to be whether SI has a unit roughly that size. The closest would be the decimeter, which is about 4 inches. But SI wasn't designed to have "equivalents" to other measurement systems. --Dhartung | Talk 04:51, 22 May 2006 (UTC)

For mental calculations from feet to metres, and vice versa, I use 1 ft = 0.3m = 30cm. It should be 30.48cm, but it works ok for everyday (shortish) measures. A common ruler, with 0 to 12 inch imperial markings, also goes from 0 to 30cm, if it has a metric side. Maybe the .3m is confused with 1/3m ? --Seejyb 21:16, 23 May 2006 (UTC)

Actually yes, 1/3 of a meter can be expressed as 33.33333333333333333333333333... centimeters (sorry, I don't know how to get that line on top of the first .3 to show that it repeats forever). However this is certainly not equivalent to a foot. I believe you're mixing apples and oranges (the metric system with the imperial system). 1/3 of a yard is a foot. Not 1/3 of a meter (which although relatively comparable, is certainly not the same unit of meausrement as a yard). Loomis51 20:43, 24 May 2006 (UTC)

May 22

How long it takes to photosynthesise

I would like to know the answer to the question "How long does it take for a plant to photosynthesise six molecules of carbon dioxide and six molecules of water into one molecule of glucose and six molecules of oxygen (a balanced photosynthesis equation), provided all factors are at their peaks?" I have asked everywhere and cannot get an answer, is it even possible to answer the question? Thank you. --Daniel 21:14, 22 May 2006 (UTC)

• That would depend on the proximity the molecules have to each other, but I can tell you right away, it's a ridiculously short time. It would be more useful to think in moles instead of loose molecules. - Mgm|^(talk) 20:56, 23 May 2006 (UTC)

How to remove a fluorine based organic grease from aluminum

I am interested in looking for a solvent or another approach to remove a fluorine based organic grease (Christo-lube MCG 101) from aluminum walls. The approach cannot damage the aluminum walls as they serve a purpose of a vacuum chamber.

Suggest a fluorine based solvent - a perfluoroalkane or perfluoroether. - this method shouldn't damage the walls at all.HappyVR 06:29, 22 May 2006 (UTC)

Would dry ice (CO2) pellet blasting work? Most solvents are pretty toxic and difficult to dispose of safely. --Seejyb 19:32, 22 May 2006 (UTC)

re organofluoro compound removal - the right solvent should just dissolve the grease (might need warming/swirling for some time though) - then it can be distilled off the grease easily - and reused - you even should get the grease back - needs a rotary evaporator or similar though.

Don't know - have you heard of super-critical carbon dioxide extraction - requires high pressures - but as you have a vacuum chamber maybe it will be ok for high pressure as well (probably not I'm clutching at straws here) - Is any damage acceptible eg minor abrasion etc, what about heating the chamber whilst under vac to attempt to volatalise the crease (catching it in a cold trap?). Sorry I can't help more.HappyVR 17:59, 23 May 2006 (UTC)

Just checked your compound (it's a perfluoropolyether I wasn't familar with the trade name) - I can't give an answer about dry ice (CO2) pellet blasting work? - actually this is totally new to me - does a compressed gas blow the pellets at the aluminium? I've never tried anything like this - my guess is that it might not work well but you never know - if you try it out I'd be interested to find out how well it worked (use my talk page if you have time)- as a last resort hot water (a lot) will remove it just as hot water will remove conventional petroleum greases. Good luck with it.HappyVR 18:10, 23 May 2006 (UTC)

Definition File

What is the meaning of definition file?

Technical term: it's a data file used by some particular program to check other data against. For example, anti-virus programs compile extensive virus definitions (markers, characteristics) to which they compare what they find while scanning files on your computer. --Halcatalyst 02:34, 23 May 2006 (UTC)

Plotting graphs for excel through visual basic

Hi. Is there a way to plot graphs through visual basic? The data and everything is already in excel, and it's all read into arrays in visual basic. It's Excel 2003 and Visual Basic 6. Thanks. - 150.203.2.85 07:26, 22 May 2006 (UTC)

Yes. You don't say where you want the graphs to appear. If you want them within Excel then you can call excel commands from VB. If you want graphs on your own form then there are a lot of different components you can put on your form that can produce graphs. You could try the OWC chartspace. If Excel 2003 is anything like 2000 the documentation is really bad but with a bit of work this can be used to produce better graphs than excel (multiple charts in one chartspace etc). JMiall 22:19, 22 May 2006 (UTC)

Evolution?

This article Wast Performs Roach was brought up a few questions ago and I'm still scratching my head about it. When I was a kid I couldn't explain how eyes came about through evolution, but eventually I learned a little more about how sensory organs worked and it started to make sense to me. I am completely baffled by this wasp and roach relationship though. I can imagine a wasp suddenly gaining the ability to burrow into a roach to eat it, or to lay its eggs, but I can't fathom how this could transgress into a mind-control waza if the wasp hadn't been conciously thinking about what it was doing. Since it obviously did evolve such skills, how does one explain it?  freshgavinΓΛĿЌ  09:38, 22 May 2006 (UTC)

What other sources do you have other than the article? Is the wasp even real? I don't see how it could do so. Also, I think a cockroach has only a cluster of neurons for a brain, and it is more of a network neural system like cnidarians have. I forget what its called. This site may help [9] title inspires the utmost intrigue. If all the facts are straight: It is like a mud-dauber wasp making a nest for this type of wasp. The only thing peculiar is the forcing of the roach to walk. Of course it is probably significantly limited control, and the wasp may only actually be steering the roach, while it is trying to run away. -- Mac Davis] ⌇☢ ญƛ. 10:00, 22 May 2006 (UTC)

Here's a much more comprehensive article (an essay actually) about the wasp by the same author: The Wisdom of Parasites. Actually, I thought it was more curious that the wasp steered the roach at all. How would the wasp know how to get to the roach's nest? It could be using the roach as a security pass or something but I still think the whole mind control thing is strange. Never mind that thought, it goes to the wasp's nest. The roach doesn't seem to be running away, though. Apparently it stops obediently when it reaches the layer, and doesn't resist when the wasp inserts her eggs. That's understandable because the second sting from the wasp takes out its ability to resist. It seems to have a reasonable level of control over the roach.  freshgavinΓΛĿЌ  10:08, 22 May 2006 (UTC)

Ironically when a human being realizes he is being controlled like that we offer him a phenothiazine. If it works, he is no longer "controlled"-- or at least doesnt feel like he is. So is a phenothiazine an anti-parasite drug or does it just alter perception of similar parasites? A new horror movie anyone? alteripse 10:54, 22 May 2006 (UTC)

I have a meeting shortly, so I cannot Google this, but it is very similar... There is a parasite that has evolved into a complex system. From memory: The parasite eggs are eaten by an ant. They move through the ant's system and to its brain. This causes the ant to lose control of normal actions and, instead, hang off the top of long blades of grass. Rabbits come by and eat the grass (and ants). The eggs hatch in the rabbit's intestines and come out when it poops. A certain snail loves to eat the rabbit poop, so it stops by. The parasite wiggles into the snail's shell. This irritates the snail, so it puts a mucus ball around the parasite and ejects it. As the parasite dies in the mucus shell, it lays more eggs. The ants love to munch on the mucus balls, which starts the whole process again. --Kainaw ^(talk) 12:31, 22 May 2006 (UTC)

Sigh. That's about enough to make me believe in God. God with a really strange sense of humor.  freshgavinΓΛĿЌ  12:36, 22 May 2006 (UTC)

This reminds me of another parasite that makes use of both birds and snails. This particular parasite (or perhaps its eggs, I forget) can survive within bird droppings. Once the droppings are dropped, the parasite can make its way into the soil, where it is picked up by snails.

Once inside the snails, a remarkable thing happens. The parasite travels up the snail's nervous system, and somehow compels the snail to climb plants or grass as high as it can. A side effect of this is that the eyestalks of the snail pulse rapidly--an amazing sight--and they also change colors. Birds are attracted to the exposed snail (or maybe slug, again I forget) and eat it, beginning the cycle anew. --Tachikoma 14:35, 22 May 2006 (UTC)

I should note that while these are condidered far too complex for dumb evolution, it isn't as complex as it appears. In the example I gave, the evolution of the parasite took advantage of existing systems. The rabbit was already esting the grass. The snail was already climbing around on the rabbit poop. The ants were already eating the snail mucus. So, a snail parasite would occasionaly get into the snail mucus and eaten by the ant. No big deal. Eventually, one of those parasites causes a weird behaviour in the ant - it climbs up a stalk of grass. This single action greatly increases that parasites genes' chance of survival to the next generation. Instead of being left inside an ant that eventually dies somewhere, the parasite goes into a rabbit and is deposited where the snails crawl around. So, there was only one evolutionary step - ant control. The rest already existed (due to previous eveolutionary steps, of course). --Kainaw ^(talk) 14:47, 22 May 2006 (UTC)

Ah yes, I didn't clarify myself that the behaviors could be explained by the reproductive success of whatever organism happened to do something a bit different. But it's still fascinating. --Tachikoma 14:53, 22 May 2006 (UTC)

Even if all those intermediate steps had already existed, the fact remains that one fateful day, a ginormous coincidence occurred that began the cycle for the first time, and it never stopped.  freshgavinΓΛĿЌ  15:30, 22 May 2006 (UTC)

I need to look up the math guy who said, "A coincidence is not surprising. They happen all the time. Absense of a coincidence is what is truly amazing." I'd like to get the quote correct and attribute it to him. --Kainaw ^(talk) 16:09, 22 May 2006 (UTC)

Nobody beats Douglas Adams on coincidences:

Now it is such a bizarrely improbable coincidence that anything so mind-bogglingly useful could have evolved purely by chance that some thinkers have chosen to see it as the final and clinching proof of the non-existence of God.

The argument goes something like this: "I refuse to prove that I exist," says God, "for proof denies faith, and without faith I am nothing."

"But," says Man, "The Babel fish is a dead giveaway, isn't it? It could not have evolved by chance. It proves you exist, and so therefore, by your own arguments, you don't. QED."

"Oh dear," says God, "I hadn't thought of that," and promptly vanished in a puff of logic.

"Oh, that was easy," says Man, and for an encore goes on to prove that black is white and gets himself killed on the next zebra crossing.  freshgavinΓΛĿЌ  16:48, 22 May 2006 (UTC)

A possible way for the wasp's behavior to evolve: Presumably the wasp already had a stinger, like all hymenopterans, and was stinging its prey to feed its young. Stinging the prey in a certain spot would create a tremendous survival advantage if it meant the prey didn't die right away. (Dead prey tends to rot, meaning it won't be available for the wasp larva for long.) Of all the millions of wasp-stings to cockroaches, it only takes one to sting in the right place. (This presupposes that placement of the sting is a purely instinctual, not learned, behavior, and therefore the behavior can be passed along in the genes.) Leading the roach to a safe place surely came later. --Ginkgo100 19:30, 22 May 2006 (UTC)

Home Made Carbon Dioxide (CO2)

How would I efficiently and cheaply create a quick source of CO2 for trapping mosquitoes? (Only things that I can make at home please). Thanks, --DanielBC 10:38, 22 May 2006 (UTC)

• How about baking soda and vinegar? [10] - Mgm|^(talk) 10:47, 22 May 2006 (UTC)

How about farting? Of course, the problem here is to get a good aim at them... Cthulhu.mythos 10:50, 22 May 2006 (UTC)

How much CO2 is ther in the average fart?--Light current 12:36, 22 May 2006 (UTC)

About 9% of a fart is CO2 [11]. The average male farts 15-17 times a day, for a total volume of 0.6 liters (there is variation from 0.2 liters up to 2 liters; source: The Ultimate Book of Farting). So an average human male farts 50 milliliters of CO2 a day (women half that because they do it less). Exhalation produces a hundred times more CO2 per day, more if you engage in some physical activity. And how bored do I have to be to research this? Weregerbil 14:03, 22 May 2006 (UTC)

IAL. I read somwhere that women do it the same amount (or is it more?)-- they just disguise it better! Actually, that info could be added to the farting artcle- it wasnt there when I looked. 9-) --Light current 14:07, 22 May 2006 (UTC)

I don't have the info in front of me, but I have seen in several places that women actually do fart less; anecdotally, I wonder if the reason may be differing hormone levels and constituents between men and women? It is common for a woman to expel varying quantities of gas at different times of her menstrual cycle, perhaps it's related to progesterone?--Anchoress 23:51, 22 May 2006 (UTC)

No its becuase they dont swallow as much air as men! I cant think of a reason why this would be tho! 9-)--Light current 00:53, 23 May 2006 (UTC)

Just breathe. Or burn something. – b_jonas 11:13, 22 May 2006 (UTC)

Breathing is what attracts the mosquitos to your body in the first place. Burning things]] works too, especially those special "antimosquito" citronella candles. The baking sonda and vinegar idea above is not a bad idea, nut the reaction won't last too long. Another alternative is to get a big block of dry ice. It's pure CO2, so when the mosquitos "smell" it, they will try to land on it and instantly freeze to death. --Chris 14:49, 22 May 2006 (UTC)

Per b_jonas, burning something is definitely a quick and easy way to produce CO2. Please do it outside, and well away from combustible materials that you don't want to be a part of your experiment. (Many commercially sold mosquito traps employ this strategy. They burn propane to produce CO2, which attracts mosquitos; the mosquitos are then captured and/or killed in various ways.)

You can also buy dry ice – solid, frozen carbon dioxide – fairly readily. It will set you back a couple of bucks or less per kilogram. Handle carefully; it's cold! One kilogram of dry ice, warmed to room temperature, is about five hundred liters of gas. TenOfAllTrades(talk) 14:52, 22 May 2006 (UTC)

Look up mosquito and 'mosquito attractant' on Google. You will find that CO2 just gets them interested, and other things are needed. From a Canadian who's been to Mosquito Hell, and back, you will also find that those various 'squito suckers' are a big waste of money. You are draining the ocean with a thimble! --Zeizmic 22:28, 22 May 2006 (UTC)

Thankyou all, yes unfortunatly I don't want to go out into the mosquitoe ridden world and fart. Maybe that's just me. Zeizmic, yeah we are in a similar situation with mosquitoes. I know the various things we need to make a trap, but we need to attract them to the trap and I was hopeing that somebody could help for a way of getting CO2 for a while (to attract them to a trap). How feasible is dry ice Chris? How expensive is it? I wouldn't think that could be maintained as a longer term solution. --DanielBC 06:21, 23 May 2006 (UTC)

We used to promote plant growth in the aquarium by yeast-n-sugar fermentation (leading to a steady supply of alcoholic waste material) but that would probably be too slow for your purpose, and a hassle to maintain. A slow drip of conc citric acid into a tall container of CaCO3 (e.g. eggshells) in a citric acid solution yields a steady supply, controllable by the drip rate. If the vessel had tall sides the CO2 would collect inside it, or you could tube it to your trap (as we eventually did for the aquarium). The only reason I mention citric acid is because we found that easy to work with for our purpose, being stored as crystals. Dry ice inside an open vacuumflask, with a funnellike cardboard hood around the top, did work to catch mozzies that have slipped thru the door and windows netting - they suffocate before they freeze, I think, because many weren't inside the flask at all. A supply is a problem, we got ours from the local canteen for free. --Seejyb 22:09, 23 May 2006 (UTC)

Siren

What is a siren and how does it work?

Awesome question! Siren. Please note that this is an encyclopedia with EVERYTHING in it, just type in "siren" in the search. -- Mac Davis] ⌇☢ ญƛ. 11:48, 22 May 2006 (UTC)

Oh, we have everything now? I guess there's nothing left to do, then.... EWS23 | (Leave me a message!) 20:00, 22 May 2006 (UTC)

Of course we have Everything. And Anything and Nothing too. --Halcatalyst 02:13, 23 May 2006 (UTC)

You forgot something... I can't tell you what though. — The Mac Davis] ⌇☢ ญƛ. 05:08, 23 May 2006 (UTC)

Looks like we don't have everyone yet. But uncyclopedia does... transwiki?  freshgavinΓΛĿЌ  05:16, 23 May 2006 (UTC)

How to hydrolise Cellulose, CMC and other

I want to know how to do: 1. the chemical hydrolise(acid hydrolyse) of cellulose, Carboxymethyl cellulose (CMC), hydroxyethyl cellulose HEC)and CMC&HEC based Hydrogel. I have to do a complete (100%) hydrolise of them. 2. I want to know, too, which is the best method to analyse and control the % of hydrolyse and to measure from quantitative point of view the reaction products (glucose, carboxymethyl glucose etc)? I have tried the hydrolise of CMC, HEC and CMC& HEC Hydrogel with sulfuric acide 97% having first a swelling phase at 37 °C for 1 hour and then diluting 10 times with water and incubation at 90-100°C for 3 other hours. The results are not good: I arrived till 25 % of Hydrolyse. Mesuring with HPLC and spectrophotometer at 540 nm.Please help me. 22 May 2006 Xh.D (Ph.D Student, Italy)

how is a football made

what type of plastic material is used to make a football and how?

See Football (ball), if it's not in there just let us know. :) Henning 18:25, 22 May 2006 (UTC)

Reason for 25°C "Standard Temperature"

Working through a calculation of electrical conductance of tap water, I noted that most tables are for a temperature of 25°C. Where and when would 25°C have been a standard ambient temperature? --Seejyb 18:26, 22 May 2006 (UTC)

It's about the temperature of an air-conditioned room. —Keenan Pepper 18:46, 22 May 2006 (UTC)

My dad's chemistry textbooks used 20°C, which is a little too cool for most people's comfort; more contemporary ones seem to use 25°, which is a little too warm. I think in both cases they're just chosen to be nice round numbers; someone thought 22° would be too hard to remember or seem too specific or something. --Trovatore 19:40, 22 May 2006 (UTC)

I was taught that STP (standard temp and pressure) was 20 Celsius and 1 Atm. Thats in UK!--Light current 22:31, 22 May 2006 (UTC)

There are a bunch of different so-called standard conditions for temperature and pressure. (They're tabulated in that linked article.) The reasons for the different standards are based in historical baggage, tradition, and convenience.

0 °C makes a good standard temperature because you can easily maintain it with a water/ice bath. 20 and 25 °C have the appeal of being close to a comfortable room temperature. 15 °C...well, someone else will have to explain that one, but it probably had a good reason, too. I'd be tempted to suggest the adoption of 26.85 °C just because it works out to a round 300 kelvin.

101.325 kPa is used as standard pressure because it's equal to the old standard atmosphere—760 mmHg (torr). 100.000 kPa is used because it's a nice round number. TenOfAllTrades(talk) 23:54, 22 May 2006 (UTC)

• The original question was about tap water. As far as I know, no public water system heats or cools tap water. Wouldn't the temperature then depend mostly on the temperature of the water supply? (And the standard then on an average?) --Halcatalyst 01:04, 23 May 2006 (UTC)

• Er, the question was about the tables that Seejyb was consulting. He happened to be doing a measurement on tap water, but that's moot. Besides, once you get the water sample back to the lab for testing, it's going to be up to room temperature anyway. TenOfAllTrades(talk) 05:23, 23 May 2006 (UTC)

posterior cervix

i need information on how a very posterior facing cervix may complicate child birth

I recommend you contact an obstetrician or nurse-midwife. --Ginkgo100 19:33, 22 May 2006 (UTC)

Footballs

after having looked at the new official world cup footballs, for the up and coming

this summer at [12] and [13], I was wondering, how does the shapes that a ball is constructed from affect the roundness of a ball, how is this ball rounder, what have they done to prove their claims that it is rounder, and seeing as it has an underlying structure of very large pentagonal shapes, how is it rounder, when surely the larger shapes decrease the roundness of a ball. Finally surely the difference in play of this ball and previous constructions is minimal as the ground will never be perfectly flat, so the path of the ball still cannot be relied on. Philc _T^E_C^I 19:04, 22 May 2006 (UTC)

I think the point of it is to travel through the air well, rather than on the ground. The difference from previous balls can't be minimal, since that would mean Adidas are just trying to cash in. Henry^Flower 22:17, 22 May 2006 (UTC)

The larger tiles will only make the ball less round if they are as flat as the smaller (traditional) ones. I don't know how they are made, but if they are molded around a sphere before being cut, the fewer seams will help it hold its shape. --Swift 00:10, 23 May 2006 (UTC)

Weird language problem

What's that disease or brain damage thing called where people have sentences that go like "I will monkey crayon sinople travel kitten walk the dog." Where they have a string of random words in the middle of the sentence or whatever? I think they said it in Muse mgazine, but I don't knwo where mine is. 64.198.112.210 19:45, 22 May 2006 (UTC)

You may be talking about word salad, which occurs with some types of aphasia. —Zero Gravitas 19:55, 22 May 2006 (UTC)

More specifically, you may be thinking of Wernicke's aphasia, or a phrase like "receptive aphasia" or "fluent aphasia". "Word salad" is a psychiatric symptom; the others are neurological diseases. - Nunh-huh 22:34, 22 May 2006 (UTC)

Hence the old psych joke that using the wrong words is simply getting your Wernicke's in a twist. Grutness...wha? 03:34, 23 May 2006 (UTC)

Then what's it called when nobody can understand what you're saying even when you have no brain damage?  freshgavinΓΛĿЌ  05:10, 23 May 2006 (UTC)

It's called vandalism. For example, an anon user has recently inserted random words to a reference desk question to create a completely nonsensical question. – b_jonas 09:25, 23 May 2006 (UTC)

Genetic Engineering

Can you alter the genetic order of the egg cell or the sperm cell before copulation, if you have the knowledge about the history or the lineage of the family, to avoid the future disease will infect the offspring?

Genetic engineering, genetic modification (GM), and the now-deprecated gene splicing are terms for the process of manipulating genes, usually outside the organism's normal reproductive process.

It involves the isolation, manipulation and reintroduction of DNA into cells or model organisms, usually to express a protein. The aim is to introduce new characteristics or attributes physiologically or physically, such as making a crop resistant to a herbicide, introducing a novel trait, or producing a new protein or enzyme. Examples can include the production of human insulin through the use of modified bacteria, the production of erythropoietin in Chinese Hamster Ovary cells, and the production of new types of experimental mice such as the OncoMouse (cancer mouse) for research, through genetic redesign.

Since a protein is specified by a segment of DNA called a gene, future versions of that protein can be modified by changing the gene's underlying DNA. One way to do this is to isolate the piece of DNA containing the gene, precisely cut the gene out, and then reintroduce (splice) the gene into a different DNA segment. Daniel Nathans and Hamilton Smith received the 1978 Nobel Prize in physiology or medicine for their isolation of restriction endonucleases, which are able to cut DNA at specific sites. Together with ligase, which can join fragments of DNA together, restriction enzymes formed the initial basis of recombinant DNA technology.

Is this possible?

Not anytime soon. alteripse 20:10, 22 May 2006 (UTC)

UK law allows parents to test embryos for genetic diseases and abort the embryo if the condition is found. The law was recently changed to allow this to be done even if the likelihood of the genetic defect causing the syndrome is below 100%. The rationale is that if e.g. the disease is a caused by a single recessive gene, then only 1 out of 4 pregnancies will be affected, so the next pregnancy will likely be OK. EdC 22:23, 22 May 2006 (UTC)

I thought the rational was "Oh noes! Imperfect babies! Costing money and upsetting their parents!", but maybe that's just me.... Skittle 23:39, 22 May 2006 (UTC)

I think that's unfair. The regulations were relaxed to allow screening out embryos which would have a 90% chance of developing eye cancer. If one is selecting which embryo to implant, it makes rather good sense to select the one that will grow up with two eyes. - Nunh-huh 23:51, 22 May 2006 (UTC)

But also note that selective elimination of a defective embryo is not what the inquirer asked about. The answer to his question is a simple "not for the foreseeable future" or a much more detailed listing of all the scientific, practical, ethical, and political barriers to be overcome before his scenario could be a reality. alteripse 02:27, 23 May 2006 (UTC)

Yes, you answered the actual question perfectly. I was just responding to a response. - Nunh-huh 03:02, 23 May 2006 (UTC)

Indeed. If one is selecting which embryo to implant. (deleted a little rant I was going to put) And of course, you aren't 'selecting the one that will grow up with two eyes', you are choosing to implant the ones that do not have a currently detectable high genetic risk of developing eye cancer. There is a difference, and I fear an often overlooked one. Skittle 16:49, 23 May 2006 (UTC)

Water protecting against bullets

How much water does one need to stop a bullet? From 5.56 up to 12.7, travelling normal bullet speeds. Would 1 meter be enough to stop most, you think? If not stop the bullet completely, at least a percentage reduction in velocity. Henning 20:40, 22 May 2006 (UTC)

I remember this being tested in Mythbusters, even a .50 was stopped within a meter if I recall correctly. - Dammit 20:48, 22 May 2006 (UTC)

The MythBusters episode in question found that slower rounds maintained underwater lethality longer than faster ones (I think as a result of sustaining less damage upon initial impact with the water). — Lomn Talk 21:04, 22 May 2006 (UTC)

Ah, these are nice answers. Thanks for swift clearance. :) Henning 21:42, 22 May 2006 (UTC)

Are slower rounds usually heavier? If so is it a case of momentum v kinetic energy?--Light current 21:55, 22 May 2006 (UTC)

According to the Mythbusters article, it's because the faster rounds shattered/deformed on impact with the water, where the slow ones sustained little damage and just slowed down. I'd like to remind the original questioner that the disclaimer about Wikipedia Help Desk not being reliable for legal, medical or dental advice also applies on not relying on our data to stop bullets, either. --ByeByeBaby 00:18, 23 May 2006 (UTC)

Why? You must be talking ballistics! 8-)--Light current 00:48, 23 May 2006 (UTC)

It depends a lot on the the size of the bullet and it's velocity and the mass. A more massive bullet will tend to retain momentum longer and go farther. A bullet with a large cross sectional area will tend to lose momentum faster. This means a long skinny bullet will tend to go farther, and a short fat one will not. A streamlined shape will go farther than one not so streamlined (I think there are bullets called wadcutters that are not streamlines at all. A faster bullet will tend to go farther, but is is not a linear progression, a bullet twice as fast will lose velocity 4 times faster. Of course one that deforms easier will slow down faster than one that does not, so durability is an issue too.

Ballshot? --Halcatalyst 00:57, 23 May 2006 (UTC)

I see you talk my language! 8-))--Light current 01:03, 23 May 2006 (UTC)

There are guns that can fire underwater, but they have to be specially designed to shoot long, heavy pieces of metal. —Keenan Pepper 03:10, 23 May 2006 (UTC)

My dream.

I am unsure if I can post this here, but anyway. The other night there I had a dream I was in a bed, which was supposed to be in my aunts house. Now the room WASNT my aunt's house, but in my dream it was. Now, at the start of the dream I woke up and found myself attached to a drip, which seemed to be supplying me with blood and some kind of intravenous medicine, which was a yellowy orange opaque liquid. I think it was supposed to be an antibiotic.

Now, where was i? I woke up and noticed this drip. SoI got out of the bed and switched off at the socket the machine which was giving me the blood/medicine, but at that, at the tube which went into my vein (in my upper arm rather than my elbow joint), I appaered to get some kind of hypodermic haematoma. like from where the tube was, a red mark, blood, spread outwards under the skin. I then removed the tube and the haemorraging disappeared.

Does anyone know what this might mean? I woke up shortly after that.

Thank you.

It means you should stop mainlining the stuff!--Light current 21:25, 22 May 2006 (UTC)

I think only you can say what this means to you, since it is your brain and your life. Someone who knows you very well might be able to guess, but you have to wonder if you want to share something so potentially personal with them until you know what it means. To start you off, try thinking about how you felt during this dream, what certain things made you think of, why you did what you did. It could even just be that you're worried about something to do with hospitals or medicine, but without knowing you and your life, how can anyone guess? Skittle 21:29, 22 May 2006 (UTC)

thank you for your quick replies. I thought there were "stock answers" for certain dreanms. I dont think it is to do with paranoia regarding medicine etc as I am interested in a career in medicine and am not afraid of hospitals etc. Thank you again anyway.

There can't really be any stock answers because there isn't any agreement that dreams have meaning in the first place, let alone what that meaning might be. But one school of interpretation would use the occasion of the dream to ask you the following questions about your life: What is there about your aunt, or the aunt-like portion of yourself, that gives you nutrition and succor? What is there about Sol, or the Sol-like portion of yourself, that cuts off that support? What was the emotional tone of the dream? Was it upsetting, or matter-of-fact? Were you upset to be connected to the IV, or upset to be disconnected, or unconcerned either way? Was Sol's action a deprivation or a rescue? - Nunh-huh 22:30, 22 May 2006 (UTC)

No its not Sol!!! Its 'So I' 8-)--Light current 22:33, 22 May 2006 (UTC)

So substitute "you" for Sol <g>. - Nunh-huh 22:48, 22 May 2006 (UTC)

Yeah thats right!--Light current 22:50, 22 May 2006 (UTC)

Just so you're clear, when Nunh-huh said, "there isn't any agreement that dreams have meaning," he meant it. You can take a look at Dream interpretation if you want. There isn't much there, though. As best I can tell from the dreams I remember, they aren't any more "windows into my soul" than my waking thoughts are. I suppose they would be if I was seriously repressed, like most of Freud's patients. Anyway, I'd recommend basic self-awareness long before I'd support something like dream interpretation. Unless you think you're psychic, though; that's the other (rather more ancient) school of thought, that our dreams predict the future. Black Carrot 01:37, 23 May 2006 (UTC)

A really easy way I find for attaching logic to dreams is just considering how it could possibly relate to the events of the day before. Sometimes the connections are really vague, but they're almost always there, if you give the brain some room for interpretation. For example, a dream about going to the zoo with your long dead aunt and the zookeeper is your teacher and he makes you write down the statistics of every animal you see. Most likely in the past day, you saw a TV show about animals, you learned how to say the word "aunt" in Hangul, and your teacher told you to smarten up and do your homework. There are studies that show that the brain sometimes creates strange stories (or our mind fills in the blanks to make sense of sequences of information) in order to promote original thought. If you think of dreams that way, you see that there's no real meaning to dreams, although you can extract reason from them.  freshgavinΓΛĿЌ  04:58, 23 May 2006 (UTC)

Dreams, flat out, don't have any meaning. Your subconscious is not trying to tell you anything! I know from lucid dreaming experience: nearly all my dreams are lucid dreams and I consciously have full control. If I'm dreaming, and my conscious has full control, how can my subconscious continue to conjure up things that "mean" something? If your conscious was trying to tell you something, it would be easier to figure out— it would not put you in a conundrum. When your subconscious tells you something it damn well does! Ever got burned before! You didn't have to think about if you should leave your hand there or take it out! — The Mac Davis] ⌇☢ ญƛ. 05:06, 23 May 2006 (UTC)

Sure dreams have 'meaning', just not necessarily very useful meaning. I know that when my Mum dreams about being chased by elephants she's been worrying about weight-loss again, when I dream about my teeth falling out I'm worrying about money, when I dream about rushing ahead of natural disasters to rescue my brothers it's time to visit home again. These things you probably already know, so they're not that useful unless you don't have time to think about how you're feeling. I consider disaster dreams as a reminder that I haven't been to see my family for too long; if I thought about it at the time, I would probably already know that. And they aren't hard to figure out unless you deliberately try not to; you made them, you decypher them. Lucid dreaming is slightly different, although it's the same you making the decisions and you're not always as lucid as you might think. Skittle 16:40, 23 May 2006 (UTC)

People who insist they have lucid dreams always amaze me... what about a dream was EVER outside your control? People just have dreams about being in control... Although it does raise an interesting question, if you could somehow force your dreams to be about purely conscious thoughts and repress any subconscious emergence, would you be forced to dream in your dream to ever get to the bottom of your mind?

Say what? Black Carrot 01:48, 24 May 2006 (UTC)

No I fully understand that there is a lot of research in the area of lucid dreaming, and it is intriguing, but what i don't see is anyone looking to figure out how its so different than every other kind of dream. After all, you are ALWAYS in control of your dream, it's kind of hard to argue that something happening PURELY in your head is conscious or unconscious. In my opinion, people are just getting better at seeding their minds with material for dreams, and then when the time comes they recollect that the dream was purely deliberate. Kind of like saying you control gravity by making it pull stuff toward the earth... dreaming is ALWAYS in your head it's just come under different interpretation when studied like this.

Whether you can believe in lucid dreaming depends on whether you believe in monism or dualism, or variations of those.  freshofftheufoΓΛĿЌ  04:00, 24 May 2006 (UTC)

Sharp pain in the chest

Hi, I'm 19 years old. I know that Wikipedia isn't a source for medical advice and I don't want to be hypochondriac but it's more of curiosity than of preoccupation. I sometimes feel a short strike of sharp pain in the center of the chest, sometimes it driffs a bit to the right and sometimes in the other direction. If I'm nervous it seems to become a little more common and other young people have told me to experience something similar so... what does causes that? thanks very much.

Sounds like wind to me, but please go see a doctor!(just to make sure)--Light current 22:22, 22 May 2006 (UTC)

It's a good thing to write all these things down for the next visit to the doctor. --Zeizmic 22:30, 22 May 2006 (UTC)

I had something similar around that ages, it turned out that the muscles on my chest were slightly too short (due to fast growth I guess). Remember ofcourse that the answers here are not by experts and if you think it could be something more serious you should consult your doctor. - Dammit 22:46, 22 May 2006 (UTC)

I forth the motion... With toe pain there are relatively few possibilities but with chest pain whatever it is is most likely not something to keep from the person who can actually save your life. ---- PCE 22:55, 22 May 2006 (UTC)

An occasional brief twinge of pain, especially if it is occuring in the context of chest wall movement, is more likely to be musculo-skeletal (say, Tietze's Syndrome or costochondritis) than cardiac in origin, but on the other hand there are heart valve problems that can give a similar sensation, so it's a good idea to be examined to determine if you have any murmurs that may indicate other problems, especially if you are playing sports. - Nunh-huh 22:56, 22 May 2006 (UTC)

I had extremely sharp chest pains a while back. Turned out that I had really bad gas. The point - there aren't enough nerves in the abdomen to go around. So, a pain in one place tends to hurt in another. I've wondered if a heart attack can feel like bad gas. --Kainaw ^(talk) 00:04, 23 May 2006 (UTC)

Yes, it can. See also myocardial infarction#Symptoms. TenOfAllTrades(talk) 00:10, 23 May 2006 (UTC)

I've also had similar pains since I was a child, though very infrequent. Always in the chest but it felt like it was "attached" to my lungs, because there was a slight restriction in breathing. It only ever lasted for a couple minutes, and though I worried a little I soon forgot. It was also always during periods of low activity. I think I asked my (GM) doctor about it a long time ago, but as it was so infrequent and there were no present symptoms, he basically said that it wasn't something to worry about unless it started becoming frequent. I got the feeling he didn't really take me seriously, though.  freshgavinΓΛĿЌ  04:47, 23 May 2006 (UTC)

I too have had these, but for very short durations (from less than a second to two seconds). I am 17 years, and these pains have been coming on and off for some months now, with great irregularity. What frightens me is that I DO have a heart murmur, but my doctor has told me there's little to actually worry about. I should soon get another check at a different doc, I strongly advice you to do the same. I too feel like a hypocondriac, but in your situation, and mine, it should be well reasoned. Henning 11:53, 23 May 2006 (UTC)

Thank you very much to all for your responses. I also have a slight heart murmur but I have noticed that my brothers also have it, so I guess it's normal. I think my situation is similar to Henning's, both in the frequency and duration, but since I feel physically very strong and can do sport without any problem, I will just forget about this (unless symptoms become worse :) ). Thanks again to all.

Why not give your doctor a treat anyway? They like to see fit young bodies from time to time. Must make a change from all us old fogies! 8-)--Light current 13:24, 23 May 2006 (UTC)

Untitled Question

Can somebody explain to me how to write and balance the following equation in a double replacement reaction?

NaOH + C₆H₈O₇ = ?

Thanks in advance!

This is a very hard one. I think you do it by the following: Pay attention in class. Take good notes. Read the textbook. Do your own homework. --Kainaw ^(talk) 00:05, 23 May 2006 (UTC)

Look higher on this very page, since we answered the exact same question two days ago. And then tell your teacher to tell the rest of their class to stop asking homework questions on the Reference Desk. Or at least coordinate with your classmates better. --ByeByeBaby 00:15, 23 May 2006 (UTC)

May 23

Electrolysis of Baking Soda

If I electrolysize a solution of baking soda (NaHCO₃), do I get O2 and H2 or CO2 and H2 at the anodes and cathodes? Thanks. --Chris 01:35, 23 May 2006 (UTC)

O₂ and H₂. The oxidation state of carbon in carbonate, hydrogen carbonate, carbonic acid, and carbon dioxide is the same, so it's not involved in the electrochemistry. —Keenan Pepper 03:35, 23 May 2006 (UTC)

Hmm...good point. Thanks! --Chris 16:31, 23 May 2006 (UTC)

I think Baking Soda dissolved in water becomes ionized Sodium Carbonate and Carbonic Acid. The Carbonic Acid decomposes into water and CO2. It takes a bit of time for this to stabilize, but once that happens electrolysing the solution will cause some CO2 to evolve at the anode as the Sodium Carbonate breaks up into the Carbonate ion and Sodium ion. —The preceding unsigned comment was added by 12.10.127.58 (talk • contribs) .

Hmmm, close, but not quite. NaHCO₃ in water exists as Na⁺ (sodium ions) and HCO₃^- (hydrogen carbonate ions). Na⁺ could be reduced to sodium metal at the cathode, but that's never going to happen because H₂ is much more easily produced. In HCO₃^-, the oxidation state of carbon is +4 and it's not going to get any higher (because the next electron is a tightly bound core electron). The HCO₃^- will be in equlilbrium with gaseous CO₂, as it always is, but that doesn't have anything to do with the electrolysis. (Someone please correct me if I got anything wrong.) —Keenan Pepper 20:33, 23 May 2006 (UTC)

True... but... CO₂ does actually form at the anode due to the heat of resistance of the electrolysis cell, but this is nothing to do with electrolysis. It forms from the thermal decomposition of HCO₃^-, which is only found at the anode because it is -ve. --Eh-Steve

I see...so definately H2 at the cathode, and maybe O2 and CO2 at the anode, but not because of the electricity? All I'm really looking for is the hydrogen. Thanks. --Chris 15:25, 24 May 2006 (UTC)

Global Warming- should we worry?

Does human activity on earth (burning fossil fuels etc) really make any difference to long term global temperatures? Or are the sun, volcanoes etc far more important. --Light current 01:49, 23 May 2006 (UTC)

You wouldn't, by any chance, have read State of Fear lately? You might be interested in the article on the book. -- Rick Block (talk) 02:22, 23 May 2006 (UTC)

...or, you might want to read about the opinions of competent scientists in our article on global warming. Crichton is sometimes entertaining, but any serious scientist can tell you he's just a hack. Sorry, Rick. :D TenOfAllTrades(talk) 04:18, 23 May 2006 (UTC)

If it makes me rich and famous, I won't complain about being called a hack by poor people with flakey white hair.  freshgavinΓΛĿЌ  04:41, 23 May 2006 (UTC)

I'll have you know that my hair is lush, brown, and flake-free. But I'm mostly a biochemist by trade, not a climate scientist. TenOfAllTrades(talk) 05:15, 23 May 2006 (UTC)

And you're poor!  freshgavinΓΛĿЌ  09:34, 23 May 2006 (UTC)

He is NOT a hack. Bastardization strikes again. Have you read the book, or looked at his works cited lists and appendices? Although it is a work of fiction, all the facts are right (except for the technologies the antagonists use). I recommend Light current read State of Fear. The fact is, we are not sure if humans can significantly (depends on your definition) alter the (entire) Earth's climate through increased CO2 emissions. We don't know if the sun, volcanos, or etc are far more important. We don't know. On the news I know they make everything seem like we know, but they're wrong. The debate is still going on, and still will until we get tired of talking about it publicly as much as right now. Why politicized science is bad. Scaremongering. — The Mac Davis] ⌇☢ ญƛ. 04:48, 23 May 2006 (UTC)

Actually, it's not really a question of which is more important, humans or other natural phenomena. Rather, it is the question whether the human impact is big enough to cause significantly adverse effects on the global climate. Not everyone agrees, but the scientific consensus is pretty much that the recent steady climate change is due to human activity and that the trend will continue. As for the debate, Crichton's book can hardly be considered any more of a contribution to this debate than the Da Vinci Code is to religion. Not that they should sit, untouchable in their ivory towers, but on such complex issues, shouldn't we give more credibility to the experts. --Swift 09:13, 24 May 2006 (UTC)

I'd still urge Light current to read peer-reviewed scientific literature, rather than Harper-Collins edited science fiction. Your mileage may vary. TenOfAllTrades(talk) 05:15, 23 May 2006 (UTC)

With all due respect, TenOfAllTrades, have you actually read a peer-reviewed paper? As the only native english speaker in my research group, I read almost every paper we generate, and let me tell you - those things are mostly incomprehensible. If you don't have (at least) a bachelor's in the area, you'd be lost in 2 paragraphs, if that. So recommending he read peer reviewed papers is an EXTRAORDINARILY bad suggestion. Raul654 16:36, 23 May 2006 (UTC)

MacDavis and I have been sparring over this issue for awhile :) I'm afraid that as far as scientific credibility goes, Crichton doesn't come off very well. I have read State of Fear, and browsed through some of his references, and find that his take on the issue is very one-sided - yes, he uses some real facts, but ignores many others which would go against his conclusion. I'll admit that it makes for a good story, but it's not a fair representation of the scientific consensus. Take a look at climate change and global warming - as unpleasant as the news may be, the debate about whether humans cause climate change is essentially over, we do. This is not scaremongering, it's facing up to the facts (the many graphs in the latter article help to illustrate the point). The question remains now what to do about it, and burying our head in the sand won't make the problem go away. — QuantumEleven 08:31, 23 May 2006 (UTC)

TenOfAllTrades, you're right—scientific literature is definitely much better than any work of fiction, although it does not appeal to the masses as well. I personally read much more scientific literature than fiction book. QuantumEleven, his ignoring of other things is certainly debatable, and it has been debated on several talk pages. I believe Anthropogenic Global Warming Hypothesis (AGW) to be now somewhat based on scaremongering, and has gone politicized. It is illegal to use certain kinds of cell phones in gas stations because of the irrational fear of the radiation heating gas nearby (I was told this by a radio technician, and it is not perfectly quoted, I warn). The US government spent hundreds of millions on clearing up general radiation scares from powerlines, microwaves, and cell phones. Its electromagnetic radiation, not nuclear radiation! It seems clear to me that we are not sure if increased CO₂ emissions are currently having a global effect in the significant altering of the Earth's climate. What part do you think differently of? You think it is totally clear that CO₂ increase attributable to a global warming? I am quite well read on paleoclimetology, I'm not just some guy that read Crichton's book and is convinced by his pretty bad bias (but it might be the truth, as a "counter"). — The Mac Davis] ⌇☢ ญƛ. 11:01, 23 May 2006 (UTC)

Uh, nuclear radiation IS electromagnetic radiation, but the frequency (and energy) is so much higher than that you get from power lines, it becomes dangerous. So it would be more accurate to say powerlines give off radio waves, not gamma waves.

No, nuclear radiation is not the same as electromagnetic radiation. Well, some of it is. Gamma radiation is indeed high-energy EM-radiation but alpha and beta aren't. --Swift 08:54, 24 May 2006 (UTC)

Mentioning mobile phone bans and radiation scares in the same breath as global warming is something of a non sequitur. Power line scares have no epidemiology to back them up; any reported symptoms are easily explainable as instances of the placebo effect or selection bias. Mobiles bans in petrol stations have some remote validity - radio waves can induce current in nearby conductors, causing sparks - except that mobiles have nowhere near enough power; ignition is more likely from exploding batteries or loose contacts (in which case ban all electronic equipment). Global warming, on the other hand, has the support of nearly the entirety of the climatological community. Personally, I can't but see the global warming "debate" from an engineer's perspective: greenhouse gasses make the world warm, so more greenhouse gasses will make the world warmer. To me, the burden of proof is on the global warming deniers to supply a theory where increased greenhouse gas levels do not affect the climate. EdC 12:47, 23 May 2006 (UTC)

No it is not a non-sequiter. It demonstrates how fearmongering is a more powerful tool than the truth. The verdict is not in on CO2 and global warming and probably will not be for a long time until the politicization of the subject is swept away.

I tend to look at it the same way as EdC. We know carbon dioxide is a greenhouse gas as much as we know anything; that's the very thing which has made Earth lovely and warm so that we could live as we do. We know that more carbon dioxide makes it hotter. We know that human activities are releasing more carbon dioxide into the atmosphere than they are locking back into trees/shells/etc. So where's the argument? And as far as the mobile phones in garages goes, I have it from someone in the industry that the bans stem from one explosion which seemed to be tracable to a man receiving a call on his phone. Nobody really knew how it could cause it, but something sparked. However, this isn't verifiable. Skittle 16:32, 23 May 2006 (UTC)

Answering Mac Davis' question on whether it is totally clear that CO2 increase attributable to a global warming: No, this is science -- nothing can be proven. The consensus, however, is that the correlation between the alleged cause and the measured effect is good enough to pass the test of science. For many the final straw was when the National Geographic had a special on global warming. Now the debate seems to be mainly on what the effect will be.

I wasn't sure if I should include the following bit on human effect, but in a crowd of vague quotes from radio technicians on cellphone legislatiure, I figured this anecdote wouldn't be the topic's weakest point. A friend of mine doing her M.Sc. in oceanography has done some research on the connection between climate data and pandemics. One of her preliminary results showed a correlation between major pandemics and some unexplaned non-negligeble fluctuations in CO2 levels. Her conclusion was that the large scale decrease in population caused a substantial enough a change in human activity to affect climate. So, yes. Even pre-industrial civilisations may have had measurable affects on the globe. --Swift 09:40, 24 May 2006 (UTC)

The science community's role is not to tell truths. It is to study and give warnings when necessary. Now the global warning has been made.

The global warming shall be a reality when other communities find it proper to their agenda. Politicians, voters, capitalists, engineers are thinking about it, e.g. in California, which is hot already (meaning hot oven). I declare the GW open! --DLL 18:37, 23 May 2006 (UTC)

I think the engineers already know it's happening. Yay for truth by concensus. Skittle 19:20, 23 May 2006 (UTC)

• This is the exact kind of fear mongering that so called mainstream "scinetists" use to try and trick people into believing in other absurd things like, evolution, environmentalism, genetics, satan, dentistry, the big bang, and the moon, I'm not buying into any of this nonsense, you go Mikey C!User:Peter cotton tail20:42, 23 May 2006 (UTC)

What about the long term carbon cycle. Does that have any effect?--Light current 22:14, 23 May 2006 (UTC)

Transgenics, Genetically Engineered Organisms.

I searched "Ananda Chakrabarty" in Wikipedia, and I was shocked not to find an informational site about him. He was a microbiologist that filed for a patent on a bacterium, psuedomonas, capable of digesting the components of crude oil. He was the first to file a patent for a transgenic. Frankly, I think this was a huge discovery. In fact, he even had to go through a court battle for this genetically engineered organism.

http://www.oyez.org/oyez/resource/case/1125/

This site is excellent in explaining the court battle. (copy and pasted):

"Diamond v. Chakrabarty 447 U.S. 303 (1980) Docket Number: 79-136 Abstract

Decided:

June 16, 1980

Argued:

March 17, 1980

Subjects:

Economic Activity: Patents Facts of the Case

After genetically engineering a bacterium capable of breaking down crude oil, Ananda Chakrabarty sought to patent his creation under Title 35 U.S.C. Section 101, providing patents for people who invent or discover "any" new and useful "manufacture" or "composition of matter." On appeal from an application rejection by a patent examiner the Patent Office Board of Appeals affirmed, stating that living things are not patentable under Section 101. When this decision was reversed by the Court of Customs and Patent Appeals, Diamond appealed and the Supreme Court granted certiorari. Question Presented

Is the creation of a live, human-made organism patentable under Title 35 U.S.C. Section 101? Conclusion

Yes. In a 5-to-4 decision, the Court explained that while natural laws, physical phenomena, abstract ideas, or newly discovered minerals are not patentable, a live artificially-engineered microorganism is. The creation of a bacterium that is not found anywhere in nature, constitutes a patentable "manufacture" or "composition of matter" under Section 101. Moreover, the bacterium's man-made ability to break down crude oil makes it very useful. "

Isn't this an important bit of scientific information that should be present in Wikipedia?

This man made it possible for others to recieve patents for genetically engineered organisms.

Even MSN has an article on him: http://encarta.msn.com/media_701765369/Ananda_Chakrabarty.html even though it isn't in much detail as it should be, I think Wikipedia should create an article explaining his contributions to the world and the important court case.

We do have an article on the court case at Diamond v. Chakrabarty. We should indeed have an article on him. You could start it yourself (you'd have to get an account to be able to create the article), or add it to the appropriate section of Requested articles.-gadfium 03:05, 23 May 2006 (UTC)

• If you can find the time to write up your own entry, instead of copy-pasting, you could also make a submission to WP:AFC. - Mgm|^(talk) 20:38, 23 May 2006 (UTC)

• He is not well known as a person -- he is known almost entirely through the case, which we do have a (not very informative) page on, as noted. --Fastfission 19:15, 24 May 2006 (UTC)

Ester Based Drilling Fluids

Drilling fluid or drilling mud is any of a number of liquid and gaseous fluids and mixtures of fluids and solids (as solid suspensions, mixtures and emulsions of liquids, gases and solids) used in operations to drill boreholes into the earth. Synonymous with "drilling mud" in general usage, although some prefer to reserve the term "drilling fluid" for more sophisticated and well-defined "muds." Classifications of drilling fluids has been attempted in many ways, often producing more confusion than insight. One classification scheme, given here, is based only on the mud composition by singling out the component that clearly defines the function and performance of the fluid: (1) water-base, (2) non-water-base and (3) gaseous (pneumatic). Each category has a variety of subcategories that overlap each other considerably (www.slb.com)

There is a new innovation in drilling fluid which use ester as the base. What is ester based drilling fluid? What are the advantages of using ester based drilling fluid compared to the conventional drilling fluid?

--170.38.99.56

Enhanced oil recovery question

The objective of EOR process is to recover the tremendous quantity of unrecoverable oil in known deposits.

The recent discussion on EOR is to use air injection. How does the air injection works to enhance oil recovery? What are the advantages and disadvantages?

--170.38.99.56

Please refer to the instructions at the top of this page, which – in part – state that you should

Do your own homework. If you need help with a specific part or concept of your homework, feel free to ask, but please do not post entire homework questions and expect us to give you the answers.

We would be glad to provide what assistance we can, provided you work within the above guideline. TenOfAllTrades(talk) 04:21, 23 May 2006 (UTC)

Question

Duuuuhhhhhhhhhhhhhhhhhhhhhh............. IS it ok if ME askz a question for ouy guys?? THank you>,? O Mneed to eat some fish, ;;; — The Mac Twat] ⌇☢ ญƛ. 05:11, 23 May 2006 (UTC)

Mac Davis, do you know, what is 2*2=4 equal to? ellol 07:15, 23 May 2006 (UTC)

Excuse you! Its "The Mac_Davis" — The Mac Davis] ⌇☢ ญƛ. 10:00, 23 May 2006 (UTC)

Very funny,  freshgavin. I'm laughing so hard. — The Mac Davis] ⌇☢ ญƛ. 10:47, 23 May 2006 (UTC)

The Ultimate Speed Limit

I've heard that the Special Theory of Relativity's Ultimate Speed Limit not only applies to material objects, but to influences and disturbances of any sort.I don't understand.How can it, I mean how can such a rule like that, possibly apply to anything that exists, not just matter and substances?60.241.147.187 09:57, 23 May 2006 (UTC)

The "speed of light" limit, is for objects with a mass greater than zero. The speed of light is the limit, because a photon's rest mass is zero, and it takes an infinitesimally small amount of force to move it: any force propels it to c, because it is weightless. Actions and disturbances are akin to energy—they are completely intangible. They don't actually.. exist. It is a property of the system, not a substance with an independent existence. You might as well ask "what is length made of?" or "what is momentum made of?" This is why the velocity limit only applies to masses, and it would take an infinite amount of energy to propel a mass to the speed of light. — The Mac Davis] ⌇☢ ญƛ. 10:07, 23 May 2006 (UTC)

I think you read his question wrong, he was asking why c applies to everything, not just the speed of objects of mass. It's probably best to think of the SToR's ultimate speed (c) as just c, and not the "speed of light". Then it's easier to say that nothing can pass the speed of c, not light, not the influence of gravity, not the disturbances in space and time. It'd take someone with a little better understanding than me to explain how gravity and time are limited to c, but I think one way to imagine it easily is if someone inserted a planet right beside earth instantly. You probably wouldn't feel the gravity from the new planet for a fraction of a second, as the influence of it's mass would be travelling more or less at c.  freshgavinΓΛĿЌ  11:06, 23 May 2006 (UTC)

I think the simplest way to elaborate on this is to say space has limitations in that nothing can propagate throught it faster than light. Of course when you start talking about quantum mechanics, some of this gets pretty fuzzy.

I doubt anyone here will be able to improve on the article on faster-than-light travel and communication; suffice it to say that in general relativity anything that can go faster than light can go back in time, and time travel really messes up the maths. -- EdC 12:33, 23 May 2006 (UTC)

Shine a very powerful visible laser beam at the moon's surface and you observe the spot of light produced there. Now you quickly vibrate your laser source from side to side over a very small angle such that the beam still hits the moon. How fast can you get that spot to move? Is it limited to c? 8-)--Light current 12:42, 23 May 2006 (UTC)

You can get the spot to "move" infinitely fast, so the answer to your second question is no. You can shine a light in two different places on the moon, and it doesn't mean that anything is travelling instantly.  freshgavinΓΛĿЌ  13:44, 23 May 2006 (UTC)

Except information ?--Light current 13:50, 23 May 2006 (UTC)

What is information? It's some little changes of energy, of matter, and all this stuff can't be transmitted faster than c! ellol 14:35, 23 May 2006 (UTC)

Look it up at information --Light current 14:55, 23 May 2006 (UTC)

To address "information" and the "laser spot on the moon" -- yes, a small movement of a laser source on Earth can cause the endpoint of the beam on the moon to "move" faster than light. However, what does this accomplish? In and of itself, information is still restricted to light speed, because no outside observer can draw information until the reflection of the beam, at its various points, has reached him at light speed. — Lomn Talk 14:58, 23 May 2006 (UTC)

The one that's always gotten me is this: You've got a very long solid pole (one light-year in length, for argument's sake). You push one end. Does the other end of the pole only move one year later? --Kickstart70-T-C 16:43, 23 May 2006 (UTC)

Yes. It's a non-obvious answer, because on earth, we are used to the idea of very small poles where you push one end and the other "instantaniously" moves. A light year is a *very* long distance (3 trillion kilometers, I think). Remember, as best we know, even gravity is limited to the speed of light. So pushing one end of the poll means that the force you impart into one end of the poll will be transmitted (probably as a compression wave) to the other end of the poll, and some velocity less than the speed of light (probably substantially less too). Raul654 16:50, 23 May 2006 (UTC)

Awareness of the push propogates at the sound speed in the pole material, typically a few km per second in most solid material. Hence much slower than the speed of light. Dragons flight 17:06, 23 May 2006 (UTC)

Right. And Kickstart, you'd probably get a kick out of Bell's spaceship paradox. ---CH 09:58, 24 May 2006 (UTC)

And even when the opposite end of the pole finally moved, you wouldn't actually see it move until 1 year later.  freshofftheufoΓΛĿЌ  17:23, 23 May 2006 (UTC)

Its a good job no ones got a solid 'pole' one light year in length. The mind boggles!--Light current 23:06, 23 May 2006 (UTC)

The moon laser puzzles me; I don't understand how one can say that the light on the moon moves. The direction in which the photons from earth travel to the moon changes as the laser on earth is moved. Where they hit on the moon is determined by the direction in which they were moving on leaving the laser source, thereafter they just go straight on (gravity and refraction etc ignored). Once the get to the moon they dont't move, they just get reflected from where the landed. There seems to me nothing on the moon that is moving, except that different photons are hitting different places at different times. That is surely not a lateral movement of any single photon? --Seejyb 23:44, 23 May 2006 (UTC)

The dot itself moves faster than C, as a result of the group velocity of the photons. Or, to put it different, if you had a bunch of people stand one meter apart and each of them start doing an Audience wave at almost the same instant, the wave could move well over C, but (a) nothing of mass is moving at C or greater, and (b) the people would have to be told ahead of time when to stand (thus, information cannot move faster than C) Raul654 02:50, 24 May 2006 (UTC)

I guess you could just call it perceived motion, just like the Bionic Man was perceived moving 10x faster than the average man, though of course it was just a crappy 1970s camera trick.  freshofftheufoΓΛĿЌ  06:08, 24 May 2006 (UTC)

No, it has nothing to do with group velocity (which travels along the wave, i.e. the direction of the laser beam). As Seejyb guessed, it is just different photons hitting different parts of the Moon. Look back at the question posed by LightCurrent and you will see a smiley. I interpreted it as a tounge in cheek marker since the question is not about motion, but rather (in Freshgavin's words) about perceived motion.

Raul654's audience wave analogy is unfortunately also wrong since the wave propogates by people rising when their neighbours do -- an example of a propogation of information (the speed of which is determined by the reaction time of the audience). A more fitting analogy would be to give the audience alarm clocks with instructions to rise up when they sounded. The clocks would be timed so that the audience would create a wave, but which travelled much faster than the audience could have created by passing on the instructions to the persons beside them. In this case, no information is transmitted through the wave signal, the information has already been planted in the alarm clocks. --Swift 10:10, 24 May 2006 (UTC)

ROCKET FINS

Today in Science Class I recieved an assignment which has us create a rocket. I have already finished the rocket but I require information on how to place the fins and where. Could anybody help me? Thanx!--Devol4 10:31, 23 May 2006 (UTC)

Always put the fins on the end. (haha, get it?) — The Mac Davis] ⌇☢ ญƛ. 10:45, 23 May 2006 (UTC)

Oh, very droll! Sum0 22:25, 23 May 2006 (UTC)

Googling for "rocket fins" and clicking on the first result brings up this page. –Mysid^(t) 11:09, 23 May 2006 (UTC)

That link doesn't tell him where to put the fins, though it does give some construction hints. Devol4, I'm assuming you're creating a rocket with a single booster on the end of it. If the wings are too far from the power source, they won't have any stablizing ability on the craft and it will spiral out of control. Some planes have wings in the middle, but that's because they're being pulled by a force instead of pushed, so it stabalizes in a different way. As long as the fins aren't going to get torched by the rocket, you should put them right at the end.  freshgavinΓΛĿЌ  11:20, 23 May 2006 (UTC)

RBC'S

RBC's are still alive and metabolizing glucose inside an SST tube prior to spinning the tube. Is this correct? (I say yes and stops after spinning, others say no because it settles at the bottom.) Please help

Please don't use ALL CAPS! It makes it look like you are yelling and can be very irritating. 222.158.163.169 12:24, 23 May 2006 (UTC)

Yes, RBC's are still alive and metabolizing glucose in inside an SST tube, both prior to centrifugation and afterwards, but at room temperature, their metabolism is a lot slower than at body temperature. Donor blood in the blood bank is centrifugated before storage, and the RBC's are still alive and metabolising after several weeks of storage at 4 degrees in the blood bank. --vibo56 12:55, 23 May 2006 (UTC)

If the blood is drawn into a fluoride tube (gray top), the metabolism is slowed, but rapid separation is optimal. alteripse 14:21, 23 May 2006 (UTC)

Sweaty drugs

I have mild hyperhidrosis (kinda-hidrosis?) and I was just reading the article on it to see how it could be treated. All of the treatments they list there are really heavy, and seem to involve long trials, have horrible side effects, and are most likely very expensive. Since my case is only very mild (I can control it by not moving too much, changing clothes a couple times a day, frequent showers) and it only effects me in the middle of summer, does anyone know of any mild treatments? Something like vitamin pills, salted drinks, or maybe cheap non-prescription drugs? (keep in mind I am not in North America and my access to very cutting-edge stuff is a little limited) 222.158.163.169 12:29, 23 May 2006 (UTC)

It affects everyone on the middle of summer! Buy a large personal fan! (and take off all your clothes) 8-)--Light current 12:49, 23 May 2006 (UTC)

Ay, that's not very nice Light current! 222.158.163.169, like the "How to ask a question" guidelines at the top of this page suggest, you might want to speak with a doctor, rather than turn to a group of anonymous Wikipedians. Good luck on this. --Swift 10:23, 24 May 2006 (UTC)

Lost My Indiglo

The electroluminescent backlight on my Oregon Scientific alarm clock/barometer only lights up around the edge. Has the electroluminscence panel reached the end of its working life? How does this happen - it isn't explained in the article. --Username132 (talk) 13:37, 23 May 2006 (UTC)

The glass on the front could have separated from the EL panel. At any rate, I think it's time to get a new...er...thingy...that you've got. --M1ss1ontomars2k4 ^{(T | C | @)} 03:56, 25 May 2006 (UTC)

J.Smith (talk · contribs)

Hello, i am an anonymous role account of another wikipedian, my password is swordfish. please inspect my account to confirm that i am a benign role account and am not hiding anything malicious--J.Smith 13:53, 23 May 2006 (UTC)

User_talk:J.Smith Blocked -Quasipalm 15:12, 23 May 2006 (UTC)

It's a really bad idea to post your password. I suspect that your account will now be used maliciously by those who know your password. StuRat 15:36, 23 May 2006 (UTC)

Pretty much the most malicious thing you can do to an account is post your password. I'm not sure what the purpose of that message was but he's super-banned anyways.  freshofftheufoΓΛĿЌ  16:07, 23 May 2006 (UTC)

Random Pixel Message

What is it called where you have a page of seemingly random pixels, but if you look at them out of focus you see a message that appears to float half a centimetre above the page. —The preceding unsigned comment was added by Bjwebb (talk • contribs) .

Single Image Random Dot Stereogram? Femto 14:08, 23 May 2006 (UTC)

Or Autostereogram, although the common name is Magic Eye picture -- Ferkelparade π 14:11, 23 May 2006 (UTC)

personalised google home page

In the case of my yahoo, if I subscribe to a news feed inside my yahoo, both heading and description of news feeds appear. But in the case of personalised google home page, only headlines appear. What should I do for both heading and description to appear?

I think the only way of doing this is to add your feeds to Google Reader then add the Google Reader module to your homepage. Clicking on a headline should pop the item up in a bubble; if it doesn't, click Edit and select "Items open: as bubbles". Matt Eason 14:58, 24 May 2006 (UTC)

Connecting a single solar cell to a home's power supply

Let's say I bought a single Sharp NT-S5E1U 185 Watt Solar Module solar cell. If I installed this on my roof, is there a way I could plug it into my house electricity system without any construction? What would be awesome is if there is something I could build / buy that would allow me to plug the output of one of these badboys into a regular outlet. Is this possible? I'm renting, so I can't do anything crazy with the power system. -Quasipalm 15:01, 23 May 2006 (UTC)

See distributed generation. I dont think its quite as simple as you imagine 8-|--Light current 15:11, 23 May 2006 (UTC)

After you put is all together, solar power costs about $1 per kilowatt-hour, as opposed to the usual of 4-5 cents. I'm putting a solar light on a detached cottage sauna, just because it is fun, and I don't want to dig a power cable (don't want to zap the porcupines!) --Zeizmic 17:45, 23 May 2006 (UTC)

How does solar power cost anything? Once installed the sun does not charge anything for shining, so where is the cost?

He's using the total cost of ownership i guess, because if for example, for arguments sake, the solar panel cost 1000(currency) to buy/install and in it's lifetime generated 1000kw/h of energy each would effectively cost 1(currency). It's when and only when the total energy generated is worth more than that of the solar panel that the energy really becomes free. -Benbread 18:16, 23 May 2006 (UTC)

Then there's the cost of the batteries because you can't really run your house on solar alone since the sun goes away at dusk. You need to store the energy somewhere. So that increases the cost. And, as far as I know, the batteries have to be replaced after ~20 years. But I'm not certain of that. Dismas|^(talk) 04:42, 24 May 2006 (UTC)

To answer the original question, yes you can - you just need a converter. See [Guerilla Solar]. Rmhermen 00:34, 25 May 2006 (UTC)

House cat behavior

I know house cats typically bring home "presents" i.e. little dead animals, but I'm wondering if it's typical for cats to eviscerate the animal and then arrange certain organs on the doorstep. I'm not *exactly* sure what the organs are, but it usually looks like the stomach, intestines, heart, liver, and one ear of a baby rabbit. They're all cleanly cut out and more or less undamaged. My cat (well--I suspect; I have no idea what else it could be and never entered my mind that it would be anything other than my cat) does this every other week or so, and rarely will he bring back a whole animal. I've been wondering about this for a while... Thanks for any help!

Category : cats. Category : animal behavior. Category : dissection ? --DLL 18:23, 23 May 2006 (UTC)

that cat sounds like its been infected by satan, that can happen if you let your animal watch too much tv, try and exorcismPeter cotton tail 20:54, 23 May 2006 (UTC)

I second the suggestion from Peter. It might be time to contact some able priests. But for giggle's sake... can you take a picture? Henning 21:03, 23 May 2006 (UTC)

I'm afraid that's quite normal. Each of our two has a favourite place for displaying the corpse, which by the time they've finished usually consists of the back end of a mouse and a little pile of viscera. Henry^Flower 22:06, 23 May 2006 (UTC)

Your cat is trying to teach you to hunt and eat the prey yourself. He knows you're a slow learner, so he's taking extra care to display the samples in an enticing manner. —Ilmari Karonen (talk) 08:27, 24 May 2006 (UTC)

Is that really true? --Username132 (talk) 18:38, 24 May 2006 (UTC)

I doubt it. Unless Harvestman has a very odd relationship with his mog, he's the daddy and the cat is the baby. Baby displays his hunting prowess to get daddy's approval, but he doesn't try to teach him. Henry^Flower 19:08, 24 May 2006 (UTC)

I'll try and take a picture next time I see it... I figured I was in for possession jokes, but oh well. It just seems a little bit more calculated then "leftovers"; but perhaps that's all it is.

Leftovers cleverly displayed so as to not look quite like leftovers - a gift for you. --hydnjo talk 18:48, 24 May 2006 (UTC)

Generic blood pressure medicines

I've been on Lisinopril for a while, but my doctor has changed me to diovan because of side effects. He said that there were about five drugs like it. Diovan doesn't have a generic, and the simular drug cozaar doesn't have a generic either. Are there drugs similar to diovan and cozaar that have generic equivalents? Bubba73 (talk), 18:11, 23 May 2006 (UTC)

We are not drs here, ask another one. Economically speaking : maybe doctors get less incentives when prescribing generics. --DLL 18:21, 23 May 2006 (UTC)

Nope, the common incentive to prescribe generics is less paperwork. alteripse 00:39, 24 May 2006 (UTC)

Diovan is an Angiotensin II receptor antagonist. There are many options in that drug category. Not all have generic equivalents (yet). In general, the older ones are less effective, but have generic equivalents. The newer ones are more effective, without generic equivalents. Also, there is a new fad for combo-drugs. So, if you take more than one class of drugs, you might be able to get it all in one pill. --Kainaw ^(talk) 18:34, 23 May 2006 (UTC)

In general, doctors don't get incentives for prescribing any medications. Talk to your doctor or your insurance company about your concerns; if there is a drug with similar effectiveness, he may be able to substitute. However, I don't believe any of the ARBs are yet available in generic form in the United States, though perhaps I am mistaken. — Knowledge Seeker দ 19:45, 23 May 2006 (UTC)

I got the Diovan filled today. It is "preferred" by my insurance comany (along with Cozzar and Hyzaar), but I can't find a generic listed. Bubba73 (talk), 20:03, 23 May 2006 (UTC)

I don't know if doctors get incentives for prescribing particular medications. I hope not. However, even if that's the case, it doesn't mean that they are not influenced by drug companies' marketing efforts. Newer drugs may be more effective (or have data that can be interpreted to make them look more effective), but older drugs have been tried on many, many more "guinea pigs". Once in a while, we have unfortunate experiences like Baycol and Vioxx. So don't automatically assume newer is better.

Molecular weight profile of a mixture of proteins or peptides

I am interested in determining the range of molecular weights in a solution of partially hydrolyzed protein. Which technique would be more powerful for this application, SDS-PAGE or size exclusion chromatography? I realize that either would work, but I'll bet one would have some advantages. ike9898 18:49, 23 May 2006 (UTC)

• I'd go with SDS-PAGE. It has several advantages. You only need a very small sample and when you get the result you can easily determine the weight (if you used a marker). If you use size exclusion chromatography, the size of the proteins in a specific fraction would depend on the flow, the eluent, pH, the conformation of the protein (not all proteins are going to be in the same state) and the gel used. To even get a proper separation would be a lot harder with the chromatography. The few times, I used it, it took ages to determine the optimum conditions. After the proteins have eluded, you still have to determine if they're pure and determine their size. Exclusion chromatography only separates, you wouldn't know the exact weight of the components after separation; only the weight relative to the other proteins. - Mgm|^(talk) 20:24, 23 May 2006 (UTC)
  • Is there any sort of lower MW limit for SDS-PAGE separation? If this technique isn't good for separating really small peptides, do you have another suggestion? ike9898 20:38, 23 May 2006 (UTC)

Physics question

Dear Wikipedians:

Why do things overwater appear blurry to swimmers underwater? And why wearing pairs of goggles make overwater things clear to the underwater swimmers again?

Thanks!

206.172.66.11 19:28, 23 May 2006 (UTC)

We've had several questions like this quite recently. Are you the same person or is it just coincidence? Anyway, the answer has to do with refractive index. —Keenan Pepper 20:14, 23 May 2006 (UTC)

wat kind of frog?

what kind of frog do you need in order to make a dinosaur cloned?Peter cotton tail 20:45, 23 May 2006 (UTC)

• how do you find the amber? isn't it hard to find? do they ever find cavemen and dinosaurs burried together? could you clone both? did people ever keep dinosaurs as pets like on old TV shows? or were they too hard to domesticate?Peter cotton tail 20:45, 23 May 2006 (UTC)

Jurassic Park is fiction and it will remain that way until there are major advances in genetic engineering. —Keenan Pepper 21:07, 23 May 2006 (UTC)

You would'nt start with a frog, and the answer depends on what species of dinosaur you want to clone. For an avian dinosaur, I'd start with another avian dinosaur. And if you were to get hold of any Triceratops DNA, by definition, any bird will do, but I'd suggest an ostrich. --vibo56 21:45, 23 May 2006 (UTC)

(Non-avian) dinosaurs became extinct 65 million years ago. Homo sapiens did not evolve until a few hundred millennia ago. At the time of the dinosaurs, human ancestors resembled shrews. We therefore would not expect that humans and dinosaurs ever would be found buried together or that humans could keep dinosaurs as pets. — Knowledge Seeker দ 22:46, 23 May 2006 (UTC)

As far as frogs and dinosaurs are concerned, according to the evolutionary trees currently in use, we are more closely related to dinosaurs than frogs are, having at least descended from reptiles (amazingly, we may be more closely related to them than some reptiles such as tortoises). If you were looking for a close relation to dinosaurs to start with, try an ostrich. even then, cloning a dinosaur from an ostrich would be about as likely as cloning a squirrel from a human. Grutness...wha? 03:03, 24 May 2006 (UTC)

Linux taking advantage of Windoze device drivers

Dear Wikipedians:

What is preventing Linux from taking advantage of Windoze device drivers to access hitherto "impossible" hardware such as Winmodems and Winprinters? (And for that matter, every single hardware device that Windoze can use, which includes all the hardware devices currently on market, and new ones as they come out on the market).

After all, most Linux systems runs on x86, the exact same hardware platform that Windoze runs on. So if Windoze can drive the x86 CPU to talk to all the hardware devices to make them work, why can't Linux do the same thing?

If there is a framework created for Linux that allows it to access all the .dll, .vxd, etc. device files in the same way Windows can, wouldn't that solve the "achilles heel" problem of hardware compatibility of Linux once and for all? Wouldn't such a framework be vastly superior to having to painstakingly reverse-engineer each specific hardware device driver per se, often failing becuause hardware manufacturers refuse to release the specs.

206.172.66.11 20:46, 23 May 2006 (UTC)

There are so many things wrong with this idea I can't possibly list them all.

1. Though they can both run on the x86 architecture, the designs of the Linux and Windows kernels are so different it's ridiculous to ask that Windows drivers run inside the Linux kernel. To name just one of the incompatibilities, Windows kernel stacks are something like 12k or 16k while Linux kernel stacks have been 8k and there's a big push to move to 4k which would greatly simplify things (because it's one page). That's just begging for disaster.

1. The Linux kernel makes no promise of binary compatibility. Even native Linux kernel modules can't be run in a kernel compiled with different options, you have to recompile them to be compatible. If you don't even have the source to the driver, you're screwed.

1. If people become dependent on proprietary drivers, there is no incentive to develop free software drivers and hardware manufactures get the impression that it's "okay" and might even say they "support" Linux because it happens to work with this horrible klugde.

1. Even if proprietary Windows drivers happen to work in the Linux kernel, they can't be legally distributed together because the licenses are incompatible. This is a big problem for distributors and users alike. —Keenan Pepper 21:04, 23 May 2006 (UTC)

Although I agree with Keenan Pepper that this is not a desirable approach, it is used in certain projects, such as ndiswrapper and Captive ntfs. --vibo56 21:26, 23 May 2006 (UTC)

I agree. 2, 3 and 4 are reasons against proprietary drivers for linux available only as a binary. – b_jonas 19:48, 24 May 2006 (UTC)

SCM

SCM and trading

• i don't know what that means, are you trying to convert me to satanism?Peter cotton tail 21:02, 23 May 2006 (UTC)

• Get away from me! *makes cross with hand* ;) --M1ss1ontomars2k4 ^{(T | C | @)} 03:52, 25 May 2006 (UTC)

What are you talking about?Yanwen 21:44, 23 May 2006 (UTC)

Supply Chain Management? That would be getting the stages of production and service etc coordinated. 5 Stages: Plan - Source - Make - Deliver - Manage Returns. --Seejyb 21:48, 24 May 2006 (UTC)

Is it possible to see clearly underwater by wearing spectacles instead of goggles?

Inspired by the preceding question, as well as this one and this one: The reason we do not see clearly underwater is that the refractive index of the cornea is almost equal to that of the surrounding water, so that we lose the refraction at the interface between air and cornea. Is it possible to correct this by wearing spectacles underwater, (i.e. with water between the lenses and the eyes)? It would be kinda nice, goggles tend to get foggy... And if it indeed is possible, what lens strength would you need? --vibo56 21:07, 23 May 2006 (UTC)

http://www.liquivision.ca/fluidgogglesfeatures.html —Keenan Pepper 21:12, 23 May 2006 (UTC)

Thanks, gotta get one of those... --vibo56 21:49, 23 May 2006 (UTC)

Thanks a trrrrrrrrrrrrrrrrrrrrrrrrrrrillion, that was the EXACT answer I was looking for 206.172.66.172 00:10, 24 May 2006 (UTC)

Or you could just get some defog for your SCUBA mask. There are commercial preparations, or you can use a dish soap solution, or your own saliva. They all work. And you can even get a prescription in your mask. --Ginkgo100 23:59, 24 May 2006 (UTC)

Leukocytes

In my book, basophils and macrophage come under the same heading, but esinophils come under their own - why don't they all come under the same, being granulocytes? --Username132 (talk) 23:01, 23 May 2006 (UTC)

Under what heading do basophils and macrophages fall? — Knowledge Seeker দ 23:06, 23 May 2006 (UTC)

Macrophages are not granulocytes. Strictly, they're not even leukocytes. They are derived from monocytes, which are leukocytes, but not granulocytes. Granulocytes come in three varieties, neutrophils, eosinophils and basophils. Macrophages might reasonably be grouped with mast cells, both being tissue cells. And mast cells have been thought to be derived from basophils (although I'm not sure if this still is considered to be correct). See mast cell. --vibo56 23:47, 23 May 2006 (UTC)

Ivy cuttings

Can Ivy be grown from cuttings?

Some kid pulled off a bunch of ivy from my walls and I'm trying to repair the damage - is there anything I can do short of waiting till fall and planting the berries? 71.199.123.24 23:31, 23 May 2006 (UTC)

Dont do anything. Ivy grows so quickly that before you can turn around, it'll be all over the place again! 8-)--Light current 23:52, 23 May 2006 (UTC)

This is the only way I've ever propagated ivy, I've never seen someone plant berries/seeds: Take end shoots, 4 nodes (sets of leaves) long. Strip off bottom 2 sets and lay them in potting soil, at 30 degrees to level, as you would vine cuttings. You can lay quite a lot of cuttings next to each other in a trench or long plant container. 2 sets of leaves stick out, two nodes covered. No roting pwder needed. Keep well watered (or cover with plastic), but not standing in water. Within 2-3 weeks you'll have roots forming between the buried nodes (other plant form roots at the nodes). If you have to "test", a very gentle tug reveals that they are starting to cling inside the soil = rooting) and at 4-6 weeks you can plant them out. As Light current said, if the original ivy has not been completely rooted out, it grows back in 2-3 weeks as a field of light green new shoots and leaves, and no need for making new plantings. Water the area where the remnant stems and roots are. One can use the time to clean the wall of dead tendrils, stalks and dirt, and fix unwanted holes or cracks the ivy may have exploited. --Seejyb 21:13, 24 May 2006 (UTC)

Ducklings...

What is it, specifically in the brain/psyche that that causes humans to find ducklings cute? I have never met a single person who doesn't go 'AWWWWW!' when they see/hold a duckling. There must be an evolutionary reason why seeing one triggers that response in us. Thanks.

Same thing that causes women to do the same thing when they see babies!--Light current 00:29, 24 May 2006 (UTC)

That does sound familiar now I think about it. There was an article years and years ago in something like New Scientist magazine that suggested a link between the way that people perceive human babies and the way they perceive ducklings. Apparently there is some instinct that their apperance triggers in us. Anyone have any more info? --84.68.240.254 00:49, 24 May 2006 (UTC)

Looking up "Kindchenschema" in the German WP (horrible stub, btw) yields an interwiki link to Cuteness, which has some pointers. --212.202.184.238 01:17, 24 May 2006 (UTC)

See neoteny for the features that comprise "cuteness". alteripse 02:42, 24 May 2006 (UTC)

It's because ducks resemble platypuses. And everyone loves those. :) --BluePlatypus 17:29, 24 May 2006 (UTC)

Mmmmm, platypus. Tastes like chicken! --LarryMac 17:37, 24 May 2006 (UTC)

It's called the "cute response" (refer to Biology, by Campbell, Reese, and that other guy). It's built-in so we don't eat our babies. --M1ss1ontomars2k4 ^{(T | C | @)} 03:51, 25 May 2006 (UTC)

"Tastes like chicken..."

Why do so many "non-standard" meats (e.g. cat, dog, rat, snake, etc.) supposedly 'taste like chicken', anyway? --84.68.240.254 23:54, 23 May 2006 (UTC)

Because they all taste foul (fowl)? 8-))--Light current 00:16, 24 May 2006 (UTC)

I doubt it's based on the actual flavor, I think it started as some sort of joke. For etymology, the Language desk is the best choice. Black Carrot 01:41, 24 May 2006 (UTC)

I agree that it's kind of a joke, possibly from the observed flavour of frogs legs, which do taste rather similar to chicken. I also remember there being some kind of reference to this in The Matrix.  freshofftheufoΓΛĿЌ  05:51, 24 May 2006 (UTC)

There's actually a (non-helpful) stub about this: Tastes like chicken. —Zero Gravitas 06:09, 24 May 2006 (UTC)

Well, it's certainly a meme today. Although my personal theory is that it's due to the fact that compared to the other meats we tend to eat (beef/mutton/pork), chicken has a relatively low-key taste. Depending on how it's prepared, the chicken flavor can at times disappear almost completely. So I always assumed that by "tastes like chicken", they meant a kind of nonintense flavor. Which figures - if something did have an intense flavor they wouldn't describe it as tasting like something else to begin with. --BluePlatypus 06:14, 24 May 2006 (UTC)

I have it on reasonably good authority that cat tastes more like rabbit than chicken. --Kurt Shaped Box 06:26, 24 May 2006 (UTC)

Ah, that's nice. I've recently eaten a very delicious rabbit meal (rabbit stuffed with stuffed dove actually). I'll have to try cats than, as they're easy to aqquire :). – b_jonas 19:43, 24 May 2006 (UTC)

• I think it was supposed to convince fussy eaters to eat something a little more adventurous. If it tastes like something they know (chicken), they're more likely to try it. Unfortunately, I can't back any of this up. - Mgm|^(talk) 08:28, 24 May 2006 (UTC)

I though thar rabbit was supposed to taste like chicken 8-) - never (knowingly) had it. --Light current 14:56, 24 May 2006 (UTC)

The rabbit I tried recently did in fact taste like chicken at first bite, but then turned out to have a much more "wild" flavor. Me gusta. --NoahElhardt 20:46, 24 May 2006 (UTC)

The frog I tried recently tasted a bit like chicken, but the fibers were skinnier, so the meat was smoother. --M1ss1ontomars2k4 ^{(T | C | @)} 03:50, 25 May 2006 (UTC)

May 24

Atmospheric gas spectrographic image

Is there an online site where you can view a composite spectrographic image of the gases in the Earth's atmosphere? -- PCE 00:23, 24 May 2006 (UTC)

Computer processing question

I am looking for a processor / server that can process a 4 Gbps serial input stream, decommute the data by reading the headers, strip out packets, and rout the data to different IP address.

Thanks

Good luck!--Light current 00:27, 24 May 2006 (UTC)

The Cell processor. From all the hype, it can do anything! You might have to wait a while, though. --Zeizmic 01:55, 24 May 2006 (UTC)

I know far more about the cell than I care to (one of the three guys whose name appears on the patent application is an almnunus of my research group; my research group is getting one of the first ones shipped to the US). For hardcore signal processing and routing, it has good potential. For pretty much anything else - especially anything complicated to program - it's a nonstarter. Raul654 02:11, 24 May 2006 (UTC)

You may be able to find a specialized router that can do this. – b_jonas 19:38, 24 May 2006 (UTC)

Flower Names

Please provide me with the English names of any of the following nine flowers. I have also posted them on my user page; you can also go there and edit the page.

• 
  Flower1;dandelion
• 
  Flower2;daisy
• 
  Flower3;carnation (Dianthus caryophyllus)
• 
  Flower4;snap dragon
• 
  Flower5;carnation (Dianthus caryophyllus)
• 
  Flower6; some kind of Limonium spp. (aka "Sea lavender" or "statice")
• 
  Flower7
• 
  Flower8; Alstroemeria (Peruvian lily)
• 
  Flower9;Queen Anne's Lace

Patchouli 00:38, 24 May 2006 (UTC)

How about a hint like UK, US, Canada, Europe, etc? alteripse 00:47, 24 May 2006 (UTC)

I live in southern California, United States.Patchouli 01:21, 24 May 2006 (UTC)

I'm no flower expert but my thoughts might narrow down your search for you... Flower 1 looks like a Dandelion but I can't really tell for sure from the picture. 3 & 5 appear to both be Carnations. 4 is either some sort of orchid or snap dragon. Probably an orchid though. And 9 looks like Queen Anne's Lace. Dismas|^(talk) 04:32, 24 May 2006 (UTC)

1. 2 looks like a daisy, no? #1 could also be a daisy. (The leaf, rather than the flower, would allow us to decide dandelion vs daisy). - Nunh-huh 06:40, 24 May 2006 (UTC)

1. 1 and 2 look like Gerber Daisies, while 4 is definitely a Snapdragon. Nrets 15:07, 24 May 2006 (UTC)

• Flower 1 and flower 2 are extremely similar. Flower 1 has a series of shorter petals surrounding the stamen in addition to the larger petals whereas flower 2 doesn't.Patchouli 15:49, 24 May 2006 (UTC)

• Flower 1 appears to be a yellow composite (a very large group of similar flowers). You'd need more information than just the blossom (such as leaf shape, details of the flower, possibly the root type) to narrow it down any further. --Serie 20:07, 24 May 2006 (UTC)

• I agree on 3, 4(def not an orchid), & 5. I've labeled 6 and 8 - not sure on #7. Could #9 also be just a carrot flower? --NoahElhardt 20:55, 24 May 2006 (UTC)

Wikipedia has no entry for carrot flower. Maybe you mean wild carrot which is the same as Queen Anne's lace.Patchouli 21:58, 24 May 2006 (UTC)

I meant domestic carrot. Your normal everyday garden carrot. (or just plain carrot if you will) That's the flower. Maybe. But Queen Anne's lace is very closely related, and if you found it growing wild than that is probably what it is. --NoahElhardt 03:03, 25 May 2006 (UTC)

regrowing limbs

Please correct me if I'm mistaking, but I'm pretty sure the human body esentially is totally new after some months because all the cells have been replaced. Is that right? So why can't a person regrow their arm, leg, etc. after they are chopped/bitten/sliced/vaporized off? schyler 01:50, 24 May 2006 (UTC)

See Stem cells at a guess! 8-)--Light current 02:11, 24 May 2006 (UTC)

I know I kind of stuck it on the end, but I wanted to know why stem cells can't regrow entire limbs. schyler 02:39, 24 May 2006 (UTC)

Because there are certain genes that only operate at very early embryonic stages and these are especially the ones that produce limbs (see HOX genes). alteripse 02:40, 24 May 2006 (UTC)

"The liver is among the few internal human organs capable of natural regeneration of lost tissue; as little as 25% of remaining liver can regenerate into a whole liver again." from Liver. I always thought that was pretty amazing. - R_Lee_E (talk, contribs) 02:53, 24 May 2006 (UTC)

The fact that the liver can regenerate seems to indicate that regeneration was common in the early stages of evolution and a trait that was retained due to the ever present need for its retention due to cell destruction as the result of bad stuff our ancestors ate (like Cashew husks and Avocado something) - just like some lizards have retained the ability to regenerate tails most likely due to the ever present consumption of tails by less than stealthy predators. But I speculate and know nothing absolutely for sure. -- PCE 07:18, 24 May 2006 (UTC)

I can't find the exact journal in which I was reading about the recent studies to find ways to do exactly that, but certainly scientists are working on it. A simple Google seach comes up wiith these recent stories: NYT: Missing Limb? Salamander May Have Answer, Wired News: Lost Limb? Worm May Hold Answers, Guardian: £10m to study how to regrow damaged limbs, etc etc. People are working quite hard on this. — Asbestos | Talk (RFC) 13:59, 24 May 2006 (UTC)

Numbered lists in word

Earlier this month, I asked ( http://en.wikipedia.org/wiki/Wikipedia:Reference_desk_archive/Science/May_2006#Numbered_lists_in_Word ) about numbered lists in microsoft word and how to get them autonumbered when I want them autonumbered but otherwise left alone by word.

I think I have found a solution to this problem: Turn "Autonumber as you type" off; select the text you want numbered and use "Format | bullets and numbereing"; Selectthe newly numbered text and copy it to the clipboard; paste it into Wordpad; Copy it to the clipboard from wordpad; Paste back into Word.

This appears to give the desired numbered text where the numbers are part of the text rather than Word magic. -- SGBailey 08:06, 24 May 2006 (UTC)

Remember that good technology is undistinguishable from magic. This "word2text" method is OK, I use it to save summaries. Word allows shifting between tables and tabulated text. Maybe a macro could produce the same ? --DLL 12:07, 25 May 2006 (UTC)

A macro would definitely do it, but you can also just save the whole file as a .txt file, close it, and when the file opens, the numbers will be plain text.

Area on sphere

how do one find the area of a square drawn on a sphere?

Simple answer, you cant, a square is 2D and a sphere is 3D, so you can not draw a square on a sphere. Stefan 09:38, 24 May 2006 (UTC)

It might be better to say that a sphere is a surface (a two dimensional Riemannian manifold) with constant positive curvature, while the plane is a surface (two dimensional manifold) with constant zero curvature. ---CH 10:03, 24 May 2006 (UTC)

Well there's a way to do triangles (it's in my friends multivariable calculus book), but I dunno about squares. --M1ss1ontomars2k4 ^{(T | C | @)} 03:48, 25 May 2006 (UTC)

as in an object with 4 sides, and their interior angle does not add up to 360 degrees. HOw do you find the area?

See Theorema egregium. ---CH 10:03, 24 May 2006 (UTC)

If you are asking how to find the area of some shape on a sphere, then perhaps we can give you a helpful answer - but in order to do so, you have todefine the shape 'exactly'. For example we could start analysing the area of a square projected onto the surface of a sphere. This isn't a square, it has curved edges. So back to you... -- SGBailey 10:25, 24 May 2006 (UTC)

BTW, did you know that an equilateral "triangle" on a sphere touching the points lat=0,long=0; lat=0,long=90; lat=90,long=any has three 90 degree corners and has an area of 1/8 of the sphere? -- SGBailey 10:25, 24 May 2006 (UTC)

You will have to express the sides of the "square" mathmatically to determine the boundaries of the double integral that will give you the area. You will probably want to solve it in spherical coordinates. You are going to have to know some calculus for this one. --Swift 11:11, 24 May 2006 (UTC)

actually, the whole thing goes like this, i am tryin' the find the area of this...

A square with the side of 10 cm, and draw loci (10cm) on each corners (quarter of a circle in a square to give the "square")

This is NOT a homework question, i just want a head start of what to do. If you do not understand what i said, tell me and i'll create an image from Paint. many thanks!

I do not understand! OK one more 'simple' answer to your to 'simple' question, between a very very very small bit more than 100 square cm to about maybe 200 square cm.

A little bit more complicated answer, as I see it this can not be answered with the data you have given, the answer depends on the radius of the sphere. If the radius of the sphere is 'close' to infinity the area will be very close to 100 square cm, if the radius of the sphere is as small as it can be (I think sqrt(50)) before the sphere 'fall' through the square it will be around maybe 150-200 square cm. But again you do not want 'simple' answers, to get a real answer you need to give more info. I guess what you want is not a answer, but a formula f(r,s)=..... where r is the radius of the sphere and s is the side of the 'square' and the result is the area of the 'square'. But sorry I will not even try to do that math. :-) (maybe I should learn wikipedia math symbols instead ....) Stefan 14:33, 24 May 2006 (UTC)

According to Square (geometry), a hemispere would be a valid "squareon a sphere" with side length = 0.25*sphere circumference and area=0.5*sphere area. Indeed presumably a hemisphere is an instance of every regular polygon with the same area and side length = 1/N * circumference. I note that this is a "valid" (?) 2 sided polygon and even a valid (?) one sided polygon! -- SGBailey 16:12, 24 May 2006 (UTC)

I don't get this. Perhaps drawing that picture would help clear things up. --Swift 08:33, 25 May 2006 (UTC)

Is this about spherical geometry?Yanwen 20:58, 24 May 2006 (UTC)

Excuse me if I'm missing something obvious here, but M1ss1ontomars2k4 says: Well there's a way to do triangles (it's in my friends multivariable calculus book), but I dunno about squares. So, find the area of a right-angled triangle (or sphere-surfaced equivalent) with shorter sides both length 10cm, and double it. Grutness...wha? 05:46, 25 May 2006 (UTC)

Grutness, You are missing something. On a sphere triangles etc don't scale like that. -- SGBailey 11:59, 25 May 2006 (UTC)

Microsoft IRC?

Is there a IRC channel related to Microsoft? Computerjoe's talk 15:04, 24 May 2006 (UTC)

When I was an IRCer, I remember a few channels on efnet.net along the lines of #fuckbillgates.  freshofftheufoΓΛĿЌ  05:13, 25 May 2006 (UTC)

Lifespan of safety razor: affected by length of hair/stubble shaved?

I feel like this is a silly question, but I really can't find an answer anywhere else. I shave my head, which is a great thing except that I go through a LOT of razor cartridges (I use the HeadBlade, BTW). Recently, I've been wondering if it causes more "wear" on a safety razor cartridge to cut longer hair than shorter hair... in other words, would I double the lifespan of a safety razor by shaving only every second day, or is two-day growth "twice as hard" on a razor as one-day growth?

I acknowledge that this is a bit of an odd question, but I'm genuinely stumped. There are a few factors here, like whether hair starts thin and thickens as it grows, and whether razors "slice through" or "cut along" the hair, which at a level this small I'm not sure about. --MattShepherd 15:34, 24 May 2006 (UTC)

Why not shave only once every 2 days. Then your blades would last at least twice as long! 8-)--Light current 16:37, 24 May 2006 (UTC)

That's exactly what I'm asking. Does cutting two-day growth cause exactly as much wear on the blade as cutting one-day growth? Or does the larger/thicker mass of hair negate any two-day shaving advantage?

Yes probably- maybe less because you dont have to go over it as much! But since youre only doing it every 2 days, your blades last twice as long! My theory, based on face shaving, is that, with longer hairs, they have more inertia and cant get out of the way of the blade quickly. Therfore, they are cut on the first pass. Shorter hairs whilst being stiffer, are harder to cut.--Light current 00:57, 25 May 2006 (UTC)

Dunno. You could find out the scientific way- perform a controlled experiment comparing the lifespans of your razors under different conditions. Black Carrot 20:21, 24 May 2006 (UTC)

I notice you're the same person who asked about the sheep powered lawn mower, so my suggestion, stop trying to sheer your lawnmower with a disposable razor--64.12.116.74 20:56, 24 May 2006 (UTC)

Or teach your sheep to graze on your beard. alteripse 23:26, 24 May 2006 (UTC)

Extremely thin teacher

Hello. I'm curious about a good teacher I have at university whose extreme thinness makes him look likes his starving, the most impressive part is his face where the skull shape can be seen perfectly, the same applies to the backbones: they can be seen through a woollen jersey. I'm pretty sure he's not an anorexic nor has Taenia solium. Somebody pointed out that there was an illness that didn't allow the victim to regenerate tissues... Any ideas? Thanks in advance. --GTubio 15:44, 24 May 2006 (UTC)

He may be an alcoholic -- or possibly have over active thyroid. You dont say how he moves fast or slow? 8-(--Light current 16:34, 24 May 2006 (UTC)

Also see cachexia, weight loss, and wasting. - Cybergoth 20:35, 24 May 2006 (UTC)

Or, you know, he may just be a Pod Person, happens all the time--64.12.116.74 21:00, 24 May 2006 (UTC)

Or he may simply have one of the forms of congenital or acquired lipodystrophy, conditions in which body fat is absent from parts or all of the body. alteripse 23:25, 24 May 2006 (UTC)

Geometrical construction

Thinking about the "area on sphere" discussion a couple of points above here, Are there articles in wikipedia detailing how to construct various shapes using ruler and compasses? -- SGBailey 16:08, 24 May 2006 (UTC)

The oddly-named Compass and straightedge article is probably ther closest to what you're looking for, found at the Construction disambiguation. There wouldn't be a set of many methods of construction, however, as Wikipedia is not a how-to book. Perhaps someone could create one on Wikibooks? — Asbestos | Talk (RFC) 16:38, 24 May 2006 (UTC)

Etching PCBs

Is it possible to etch PCBs in a solution of copper sulphate (say) or other electrolyte by using a sort of reverse electroplating method? If so, why, apparently, is it not used?--Light current 16:24, 24 May 2006 (UTC)

There is such a thing as electrolytic etching. But I do not think it's useful for PCBs. You'll get an oxide layer on the surface, which eventually will become passivated. So it won't remove material from the suface, and probably won't break the conduction. With the opposite process, you're starting with copper sulphate in solution, and on reduction, the copper becomes solid. However, when you oxidize the copper in water, the most immediately available reductant is the water protons. So you form hydrogen gas and copper oxides, which are not soluble. --BluePlatypus 17:26, 24 May 2006 (UTC)

Does galv-etch look like that? I used to do PCBs with good ol' FeCl3 — it's been many years but I remember the smell like it was yesterday :-) Weregerbil 17:36, 24 May 2006 (UTC)

My idea is to try to avoid FeCl3 etc. Wondered if electro -etching would do it!--Light current 01:01, 25 May 2006 (UTC)

raw egg peeler

what chemical reaction will the egg and a vinegar have?

Eggshell is mostly calcium carbonate and vinegar is a solution of acetic acid. That's all you need to know. —Keenan Pepper 18:31, 24 May 2006 (UTC)

The CaCO₃ and vinegar will react to produce CO₂. --M1ss1ontomars2k4 ^{(T | C | @)} 03:34, 25 May 2006 (UTC)

Biologists/Catfish/Plecs/Omega eye

Hi. I'm currently in the process of creating a page for 'Omega eye' or 'Omega iris' - I haven't created it yet it's in the planning stage. It should be a short article just explaining the term plus references. I have all the info I need except:

Does the 'omega iris' structure occur in other animals than suckermouth catfish?
and
Amongst catfish is this iris structure confined to the family Loricariidae ?

Thanks.HappyVR 18:21, 24 May 2006 (UTC)

• I don't kow what exactly an omega iris in catfish looks like, but goats and sheep have irises which look like thetas. ;-) --Fastfission 19:10, 24 May 2006 (UTC)

Another Javascript question...

So far my javascript questions have gotten very quick and prompt answers here, for which I am quite grateful. Here's one more...

I'd like to know if it is possible to use Javascript to simply read from a different webpage URL. That is, I'd like a function which could read the contents of a web page, or something along these lines, and then, say, insert it into a form element on the page which is holding the code.

I can do everything except read the page. One way I tried was to try and have the script create a new window with a URL, grab the document elements from that new window, and close the window. It didn't work -- I couldn't grab the document elements, it kept saying they had no properties.

I don't know if this is a DOM issue or a scoping issue or what -- it seems like something Javascript should be able to do via the browser, but I haven't found a way to do it yet. Googling and browsing the Javascript manual turned up no likely candidates. Is it possible, or does it require some sort of bulky applet? --Fastfission 19:06, 24 May 2006 (UTC)

For security reasons, Javascript is not allowed to read data from another site. If it is from the same site, you can open the new page in a frame or window and view the innerHtml of the document object (or the document.body object). --Kainaw ^(talk) 23:07, 24 May 2006 (UTC)

You can also use XMLHttpRequest, the technology underlying AJAX. EdC 23:37, 24 May 2006 (UTC)

• OK -- innerHTML seems to do at least some of the work I want, though some tinkering will still be needed to make this work right. Thanks! --Fastfission 01:58, 25 May 2006 (UTC)

PLANTS

Hello,

I would like to know if plants release carbon dioxide at night.

Thankyou

Yes. --Ginkgo100 00:12, 25 May 2006 (UTC)

Why? — The Mac Davis] ⌇☢ ญƛ. 05:01, 25 May 2006 (UTC)

Take a look at the image of plant cell structure. Plant cells have mitochondria, which consume O₂ and produce CO₂. They also have chloroplasts, which consume CO₂ and produce O₂. In the daytime, activity of the chloroplasts outbalances the activity of the mitochondria. At night, it's the other way around. --vibo56 10:13, 25 May 2006 (UTC)

Journal paper with a one-word abstract

Years ago I read about a research paper with a one-word abstract. I don't recall what the paper was about, but it seems to be either a math or physics paper. The title of the paper poses a question and the abstract answers it in the negative with "no."

I assume the paper was not made up, but I don't really know. Does anyone know of a paper like that?

Doesn't sound familiar, but it does remind me of the paper "Electron Band Structure in Germanium, My Ass" (Google will give many results for this). Confusing Manifestation 01:02, 25 May 2006 (UTC)

Hajdukovi´c, D., and H. Satz, 1992, "Does the one-dimensional Ising model show intermittency?," preprint CERNTH-.6674/92 and BI-TP 92/43. [14]

How about the Philosophy professor that asked "Why?" and was handed a paper that answered "Why not?".  freshofftheufoΓΛĿЌ  05:06, 25 May 2006 (UTC)

five a day

with all this stuff goign round that we need to eat heathly and that we should eat 5 fruit or veg a day but why can u only count fruiut juice once, no matter how much u drink?

I'm no expert, but I think that variety of fruit and veg is just as important as quantity. And it doesn't just affect juice - you can't eat 35 apples a week and count that as five a day either. Not only does your body need a bit of everything, but also there exist interactions between different components of nutrition - i.e. Nutrient A helps you get the most out of Nutrient B. I believe an example of this is you need Vit C to help you get the most out of iron. Also the thing with fruit juice is that for all the smoothies which are just untreated fruit, there's the Sunny D's of this world, which you wouldn't want to overdose on. --The Gold Miner 21:05, 24 May 2006 (UTC)

It's not true that you just count fruit juice once; 8 ounces of fruit or vegetable juice = 1 serving.--Anchoress 21:08, 24 May 2006 (UTC)

That is normally correct, but sometimes liquids don't count. Studies on fruit/vegetable intake are commonly skewed by the idiocy of the participants. So, they are very particular about items that count. They try to limit liquids. Luckily, I work on hypertension studies, but I work with people who do the dietary studies. They constantly have the following scenario: "How many fruits did you have today?" "Three." "And what where they?" "A cherry coke, an orange soda, and a pack of grape gum." "How about vegetables?" "Two." "What were they?" "Ketchup and mustard." --Kainaw ^(talk) 23:04, 24 May 2006 (UTC)

Pfft. Everybody knows that ketchup is made from fruits.

The other problem with fruit juice is that it is often sweetened and extended with high fructose corn syrup derivatives, and you are getting the same wonderful health benefits as if you ate spoonfuls of sugar from the sugar bowl. Much "fruit juice" should simply be labeled "Sugar Water". alteripse 23:23, 24 May 2006 (UTC)

A disadvantage of fruit juice is that it contains no fiber, unlike actual fruits and vegetables. And without fiber, you would be very, very uncomfortable (and at risk for colon cancer). --Ginkgo100 00:11, 25 May 2006 (UTC)

I guess it depends on where you're from, but where I live, a beverage cannot be labelled 'fruit juice' if it contains *anything* other than fruit juice. It has to have another name, like fruit beverage or fruit cocktail. Of course, this can escape the notice of people who either don't want to give up their Tang, or don't know any better, but we're not talking about the relative stupidity of people, we're talking about what qualifies as part of RDI for fruit/veg. Also, the RDI for fruit/veg is for the phytochemicals and other nutrients, not for the fibre (lettuce and watermelon contain almost no fibre either), and while some nutritionists make a point of suggesting that a person's entire intake of fruit/veg not be juice, most places that list guidelines for RDI do not place juice on a lower rung of acceptability than other forms.--Anchoress 00:18, 25 May 2006 (UTC) Addendum I guess I should add though that if the person is diabetic or borderline, fruit juice probably *would* be discouraged because of its effect on blood sugar.--Anchoress 00:39, 25 May 2006 (UTC)

Schwassman-Wachmann

What's the danger that the comet/asteroid pieces of Schwassman-Wachmann will hit the Earth tomorrow? Is there reason for concern or is it just another one of overblown internet stories? --Shadarian 21:43, 24 May 2006 (UTC)

Overblown internet story. --Serie 22:45, 24 May 2006 (UTC)

If you're interested in more details, an astronomer talks about the nonsense of the story here. — QuantumEleven 08:25, 25 May 2006 (UTC)

OK, we are tomorrow, but it is not 21:43 yet! --DLL 10:45, 25 May 2006 (UTC)

fusion vs. fission?

Would someone post a synopsis (or short answer) to the following:

         How do emmisions from a fusion reaction compare to emmisions from a fission reaction.
                                      Thanks, *email removed*

• One produces hard radiation, the other produces helium--64.12.116.74 22:12, 24 May 2006 (UTC)

• Fusion = melting together of nuclei of small atoms
• Fission = splitting of nuclei of large atoms.Patchouli 22:17, 24 May 2006 (UTC)

You could read fusion power and nuclear power for some information. Basically, the spent fuel from a fusion reactor is just a tiny, tiny quantity of helium. The plant itself will become radioactive; however, because you have a choice of what materials the plant is built from you can choose ones which, even if bombarded by radiation, don't remain dangerous for very long (think years of decades rather than millenia). You don't have such a choice with a fission reactor, because the fuel itself is the major component of the dangerous waste. (though there are research efforts to use thorium fuel instead of uranium; spent thorium fuel is dangerous for much less time than spent uranium fuel). --Robert Merkel 22:25, 24 May 2006 (UTC)

Also see aneutronic fusion, a way to almost eliminate the hazardous and wasteful neutron radiation. —Keenan Pepper 23:55, 24 May 2006 (UTC)

I removed the email address. --M1ss1ontomars2k4 ^{(T | C | @)} 03:32, 25 May 2006 (UTC)

Crows and seagulls as food?

Does anyone know what crow or seagull meat tastes like? Are these birds regularly on the menu in any part of the world? Some of them are massive and look like they have a lot of meat on them, yet I never heard of anybody eating them.

Crows are sometimes hunted (and more rarely eaten) in the U.S. but seagull are protected species here. I have never "eaten crow" myself, except in the figurative sense. Rmhermen 00:19, 25 May 2006 (UTC)

Tastes like chicken (foul) 8-))--Light current 00:49, 25 May 2006 (UTC)

It is quite well known (though not necessarily true) that crow/raven is eaten in some Western areas of China. You can assume, though, that they are not street crows, and are probably relatively clean. Scavengers are generally leaner than fully domesticated animals, so you can imagine that the meat would be tougher than chicken. I imaging the difference between chicken and crow would be not dissimilar to the difference between cow and horse (sometimes eaten raw in Japan).  freshofftheufoΓΛĿЌ  04:59, 25 May 2006 (UTC)

We have an old nice recipe book here (in France). One starts like : "Prenez trois jeunes corbeaux, prêts à s'envoler ..." Take three young crows, ready to take flight ... : obviously, if you take them in the nest, the flesh is palatable. Either ... --DLL 10:43, 25 May 2006 (UTC)

May 25

too hot vs too cold

hi, i'm currently sharing a house with 4 others in the UK. I, having been raised by frugal parents in the north (scotland) feel more comfortable in a cold house (i.e. no central heating), however my cohabitants, raised in the tropics of the south east of england, start moaning about the cold once the temperature drops below 25c. ignoring then minor inconveniences such as the melting ice caps, is it healthier to be cold or hot or doesn't it matter? i'm obviously not talking about a choice between the sahara or the arctic, but say, 15 degrees vs 20, or 10 vs 15.. thanks! 87.194.20.253 00:05, 25 May 2006 (UTC)

I think it's a fairly complex question. On the one hand, being cold, even by a couple of degrees, over a long period of time can suppress your immune system; but on the other hand being a little bit chilly burns (a few) more calories. Moreover: the colder it is in your home compared to the outside temp the more humid it'll be, which will be better for your skin. However, humidity encourages the growth of microbes like mold. I understand that being too warmly clothed/blanketed is strongly associated with susceptibility to crib death, but I don't know if that extends to warm ambient temperatures or if it's just swaddling. I grew up in a chilly home too (18-22 during the day and 14-16 at night, furnace turned off from May to October), so I completely empathise with your POV. AFAIAC, thermostat nudging should be a misdemeanor.--Anchoress 01:51, 25 May 2006 (UTC)

Whatever happened to "toughing out" the weather anyway?  freshofftheufoΓΛĿЌ  04:55, 25 May 2006 (UTC)

At that temperature range, it doesn't matter. We're not talking about hypothermia here. — The Mac Davis] ⌇☢ ญƛ. 05:03, 25 May 2006 (UTC)

Feynman Problem

The following is from Surely You're Joking, Mr Feynman!. Does anyone care to venture the answer?

The problem is this: You have an S-shaped lawn sprinkler--an S-shaped
pipe on a pivot--and the water squirts out at right angles to the axis
and makes it spin in a certain direction. Everybody knows which way it
goes around; it backs away from the outgoing water. Now the question is
this: If you had a lake, or swimming pool--a big supply of water--and
you put the sprinkler completely under water, and sucked the water in,
instead of squirting it out, which way would it turn? Would it turn the
same way as it does when you squirt water out into the air, or would it
turn the other way?

JianLi 00:34, 25 May 2006 (UTC)

According to the Feynman sprinkler article, scientists have tried this experiment using air instead of water, and it doesn't spin at all! --Cadaeib (talk) 01:54, 25 May 2006 (UTC)

This makes sense to me [sort of]. Imagine the regular sprinkler: water that exits it is moving at a high speed, and since it's moving normal to the lever arm, it has an angular momentum. Since angular momentum is conserved, the sprinkler must pick up equal and opposite angular momentum. Now picture the Feynman sprinkler. It's sucking in water that was stationary; hence, no angular momentum to begin with. Then, as it gets sucked into the sprinkler, there's no transfer of angular momentum. Nothing happens. -- Filliam H Muffman 03:10, 25 May 2006 (UTC)

Not so much that the water was stationary to begin with but that it was stationary at the beginning and the end of the process (when only considering the angular momentum). You could just as easily imagine a water sucking machine that expells water out the end of it, which would naturally move in the direction it was sucking. The underwater sprinkler, on the other hand, catches the water it sucks in, and thus there is no overall angular momentum.  freshofftheufoΓΛĿЌ  04:50, 25 May 2006 (UTC)

rocks

I have there types of rocks that I am trying to find out if they are metamorphic, sedimantary, or igneous can you please help me? The three rocks that I have are minerals and they are as followed:

1. umangite 2. goyazite 3.aragonite

Could you please tell me or help me to figure out what they are?

Thanks Eliza Marie

Well, we have stubby articles on two of these which don't spell things out but do leave clear hints. <mineral.galleries.com> spells things out a little more clearly for at least one of them, though here A search on the same site lists umangite as a natural source of copper selenide and goyazite as strontium aluminum phosphate hydroxide. That alone may give a clue... Grutness...wha? 05:58, 25 May 2006 (UTC)

antimony

We had plumber over today to do some soldering. I don't think the house was well ventilated. Does soldering with tin and antimony solder release toxic concentrations of antimony? KeeganB

You're fine. It's a myth that antimony is toxic, because there used to be a nasty compound of antimony around. I've done a lot of plumbing soldering, and there are few fumes. The nastiest thing one can do is electronics soldering, and suck in all that good rosin fume. More info: [15]--Zeizmic 12:04, 25 May 2006 (UTC)

convert hydrogen into BTU's

I am trying to find out how much hydrogen it takes to be equivalent to one US gallon of gasoline. I need to convert this amount of hydrogen into BTU's. Example: 1 gallon of gasoline = 124,000 BTU’s

Try higher heating value. Also see British thermal unit and gallon for information on converting from SI units to whatever collection of rods and hogsheads Americans still use. --Robert Merkel

see Heat of combustion

Just to be pendantic, it also depends what you do with the hydrogen. Are you going to burn it? Make it undergo nuclear fusion? Annihilate it with an equal amount of antimatter? The amount of energy you get out in each case is different :) — QuantumEleven 08:21, 25 May 2006 (UTC)

I wouldn't say that's pedantic at all. But since he's using it in comparison to gasoline, I'd say he's probably working in the context of cars. Therefore, we're probably talking about the combustion of hydrogen, but the question is whether the car is powered by a combustion engine or fuel cell. See hydrogen vehicle. splintax ^(talk) 10:30, 25 May 2006 (UTC)

What is the evolutionary rationale for 'men' (masculine gender)?

What is the evolutionary rationale for ‘men’ (masculine gender)? – They don’t give birth, but they increase with their genom the genetic variation. That's be-cause when organisms reproduce sexually, some genetic "shuffling" occurs, bringing together new combinations of genes. This shuffling is important for evolution because it can introduce new combinations of genes every genera-tion. But why do men not have babies either? – Is it that hermaphrodites, dou-bling the numbers of babies, would lead to overpopulation, giving the relative high age mammals reach? Therefore ‘men’ are welcome to increase genetic variation, but not the number of babies: quality not quantity. Having reached the level of mammals the animals are already quiet robust. And in this line of questions, why is it that there are about 50% men and 50% women? - Less than 50% of men would reduce the total genetic variation exposed by men. This would result in the mating process to a reduction of genetic variation, making men an obstacle to optimal evolution.

Why do you put men in quotes? You could just as easily say why do we need women? The sperm is equally important as the egg! I expect you want a scientific answer. I like this one [16], because I thought of it myself before learning of the book. — The Mac Davis] ⌇☢ ญƛ. 05:49, 25 May 2006 (UTC)

See Evolution of sex Raul654 05:54, 25 May 2006 (UTC)

I don't think they were questioning the importance of the sperm relative to the egg, simply why men didn't bare young as well, since that would double the number of potential babies. Skittle 09:50, 25 May 2006 (UTC)

Instead of picturing the world as it is now, consider the time before land animals. When our ancestors were aquatic, the female spurted out one set of gametes and the male the other. When you see it this way, you realize that no one sex is really giving birth -- both are putting their gametes out in the open where they can fuse. Fast forward to land animals, and the sperm and egg still needed to meet together in an aqueous environment, and so sex evolved. Some species, such as reptiles, then laid the fertilized egg outside the body, others, like mammals, kept it inside the female during all of gestation. But as you can see, this is just the result of evolutionary chance: both sexes are creating the fertilized egg, but the female happens to store it in her body until birth. — Asbestos | Talk (RFC) 11:45, 25 May 2006 (UTC)

Cellulose hydrolysis

From time I am facing one problem. I am trying to do 1. the acid hydrolyse of cellulose, Carboxymethyl cellulose (CMC), hydroxyethyl cellulose HEC)and CMC&HEC based Hydrogel. I have to do a complete (100%) hydrolise of them. 2. I want to know, too, which is the best method to analyse and control the % of hydrolyse and to measure from quantitative point of view the reaction products (glucose, carboxymethyl glucose etc)? I've tried the hydrolise of CMC, HEC and CMC& HEC Hydrogel with sulfuric acide 97% having first a swelling phase at 37 °C for 1 hour and then diluting 10 times with water and incubation at 90-100°C for 3 other hours. The results are not good: I arrived till 25 % of Hydrolyse. Mesuring with HPLC and spectrophotometer at 540 nm.Please help me. 25 May 2006 Xh.D (Ph.D Student, Italy)

Dimming and SADness

Does anyone know of any work relating the climatological phenomenon of global dimming with increased clinical depression due to the seasonal affective disorder? If global dimming, according to the Maldives trial, can account for a 10% reduction in sunlight in poluted areas, that surely must have an effect on the mental health of the population. Are there any studies referencing increased prevalence of depression in industrial areas, of which sunlight may be a significant factor? — Gareth Hughes 10:44, 25 May 2006 (UTC)

I think you are grasping at straws for this correlation. The dimming was at 5% and is now improving (hence global baking). A small latitude change in location is much greater. I have a SAD element to my depression, and it is triggered by the very large sunlight dimming in the fall, for the northern areas. --Zeizmic 11:44, 25 May 2006 (UTC)

Bears in Africa

Are there wild bears in Africa? Lapinmies 11:19, 25 May 2006 (UTC)

The Atlas Bear, now extinct, was the only bear native to Africa. — Gareth Hughes 11:37, 25 May 2006 (UTC)