Wikipedia:Reference desk/Archives/Science/2007 January 22

January 22

Hypothetical

I read recently about a woman who was getting (or got by now) a uterus transplant. This made me wonder. If a testes transplant was performed and the recipient had a child afterwards, would the child share the genes of the recipient or the donor? --The Dark Side 03:28, 22 January 2007 (UTC)

I don't know if such a procedure exists, but I doubt it would result in a fertile male. I imagine the associated trauma of surgical removal and reattachment to a new host would destroy the ability to produce new sperm. I'm not sure what to make of the "uterus transplant" - can you link to your source? I am assuming the transplant occurred BEFORE the pregnancy, and that the fetus was not transplanted in. This all sounds a bit fishy, anyway. Nimur 03:49, 22 January 2007 (UTC)

The donor. - Nunh-huh 04:14, 22 January 2007 (UTC)

Yep, the donor. Unless there was a secondary "transplant" of the recipient's germ cells into the testes… but now this is becoming absurd, because what if we first "transplanted" the donor's nuclei into the germ cells of the recipient. Oh my, never mind me! − Twas Now 04:20, 22 January 2007 (UTC)

Just a heads up uterus transplant planned article. —The preceding unsigned comment was added by Cody.pope (talk • contribs) 05:22, 22 January 2007 (UTC).

Geez, that bot was fast. I went to sign the second I posted the first comment, got an ec when trying to repost and then bam! --Cody.Pope 05:24, 22 January 2007 (UTC)

Junior (film), anyone? Aaadddaaammm 20:41, 22 January 2007 (UTC)

Amp hours...?

What would be the amp hour rating of a 3000 farad capacitor or what is the conversion factor for farads to amp hours? -- Barringa 05:57, 22 January 2007 (UTC)

Can't it be worked out? Given that F=C/V and 1A=1C/s where F=Farad, C=Coulomb, V=Volt, and s = time in seconds, and from Ampere-hour that 1 Ampere-hour=3600C (3600 Ampere-seconds), in a 300V circuit, from F=C/V we get 3000=C/300, thus (300)3000=C/1, thus C=900000. 900000/3600=250 Ampere-hours. If someone could check my calculations and methodology that would be great :)--inks^T 08:41, 22 January 2007 (UTC)

Your arithmetic certainly follows ...so if I use it to create a table then I should be able to insert whatever number of farads or voltage I have and with a little more work be able to figure out how many farads at a certain voltage I need for any number of amp hours and the cost:

$110/cap	# of Caps (@ 2.7v each)	F	C	V	A	s	AH
$550.00	5	3000	36000	12	10	3600	10
$1,540.00	14	3000	108000	36	30	3600	30
$12,320.00	112	3000	900000	300	250	3600	250

-- Barringa 12:02, 22 January 2007 (UTC)

Stethography

How Stethograph can be used for recording of respiratory phases. How we can compare various graphs obtained eg. between Apnea and Dyspnea —The preceding unsigned comment was added by 220.227.116.220 (talk) 07:09, 22 January 2007 (UTC).

Is this like Spirometry? Rmhermen 22:34, 22 January 2007 (UTC)

Planetary positions in the future

Is there any website that marks the position of the planets in our solar system for the next few centuries? If, for example, I wanted to know whereabouts in their orbits Mars, Neptune etc. would be in 2100, is there anyway to find out? A Flash or Java map would be nice. 58.7.143.115 08:15, 22 January 2007 (UTC)

Although not a website, almost any commerical astronomical software will show you this - something like KStars, Starry Night or RedShift. Perhaps the best bet would be Celestia - a free planetarium for windows. --Neo 08:31, 22 January 2007 (UTC)

Celestia works on Macs too! -Cody.Pope 18:55, 22 January 2007 (UTC)

Thanks, this thing's great! (I wasnt logged in as OP) Battle Ape 02:14, 23 January 2007 (UTC)

There's also an ephemeris. JackofOz 02:59, 23 January 2007 (UTC)

Water Fuel

Let us assume we have a very high compression ratio engine.In the case of a diesel engine, the fuel(diesel) would ignite and expand and push the cylinder down due to high compression temperature. now,if we were to put something like WATER or liquid air, then would not that vapourize and push the cylinder down too?? —The preceding unsigned comment was added by 61.1.131.12 (talk) 13:34, 22 January 2007 (UTC).

No, on many levels. On a practical level, if a diesel engine ingests water, you end up with a very broken engine. On a theoretical level, water cannot undergo combustion. Ultimately, if you compressed it enough I suppose the water would dissociate itself back into hydrogen and oxygen, which could be made to combust, but you would have to put in more energy to do the compression than you can get out of the combustion. --Robert Merkel

On a very, very theoretical level you might reach temperatures and pressures where fusion is possible. But then it would be a really interesting question what material your engine is made of - there is no material known to man that is able to withstand even conditions very far from those. TERdON 16:00, 22 January 2007 (UTC)

You mean a steam engine, which boils water into steam, and uses that pressure to push a piston? They were a staple of industry a century or so ago, but was rendered mostly obsolete by the internal combustion engine we know and love today. Cyraan 18:35, 22 January 2007 (UTC)

what i actually meant that the expansion of fuel(diesel) into combustion gases from liquid would drive the cylinder, then why not use water which would have the same effect??? —The preceding unsigned comment was added by 61.1.131.123 (talk) 03:42, 23 January 2007 (UTC).

You are possibly mixing up the compression, which is a physical process (and works for water) with the combustion. Diesel fuel is compressed, then it combusts, causing expansion. Since water cannot undergo that chemical reaction (it cannot combust), you could not obtain "the same effect." 171.64.91.48 21:19, 23 January 2007 (UTC)

Well we know that if ice(or water) is dropped on a hot pan,we would get an expansion effect.So it possible to design an engine that uses this principle?? —The preceding unsigned comment was added by 61.1.131.181 (talk) 11:07, 25 January 2007 (UTC).

Some say you can add some water to the combustion process in the correct ammount, at the correct time! Theres a slight catch, I've yet to find proof of concept if you dig really far youl just find alot of unlikley technology -- now granted I would love to test some of them, for better or worse (I've tried a few) But most of them have very specific requirments. If you mean can you run a car completly off of water, its a steam engine, and you need to rework the engine to do it. If you mean can you suplement the fuel in a ICE, yes you can. The thing most people dont keep in mind is that you have to account for everything in play, including the compression, the tempeture, the hot and cold spots (The cylinder does not heat up evenly) and the cooling effect that water will have. There is a chance of corosion too, engines were not built for water (Some vehicles are built to go through/under/over water but they are specificly designed(or moded) to do such!) If you truley want to test this, I suggest you get a little 4 cycle lawnmower engine, get some kind of mechanical load on it, get a 1 gallon or 1 liter bottle and fill it with fuel, see how long it takes for the engine to run dry. Then with direct port injection (which is the 'best method' if I'm remembering correctly) try some various nozzles, at diffrent pressures, and at diffrent times. I believe you want it sprayed right after the fuel is added but before its ignited, but not to much before or you may slow/stop the process, so maybe RIGHT before or exactly when the spark happens. Keep in mind the spark dosnt kick right away eighter, it takes (granted not that long) a little time for the entire fuel/air mixture to burn (of what does burn) and if you feel the need to get really fancy, mesure your exhaust of this little engine. But just remember you want a constant load, and probibly a fairly constant RPM for the tests. if and only if you find the best method, and the best method would I suggest you buy a working rust bucket, and do the same to that engine, try it before and after, see how much your milage/emmisions improve. From what I've read (but I dont believe all of it) Your car will run cool enough to touch, including the exhaust manifold, and the oil -- I suggest if you wana see you get a remote thermometer of some kind.

Blood conductivity.

What is the conductivity of blood? what is its value?

You may wish to review [1], and [2]. Conductivity of the blood changes, based mostly on the count of red bloodcells. This is often measured for stroke patients -> see [3] for an interesting method by which it is measured. Hipocrite - «Talk» 15:56, 22 January 2007 (UTC)

I remember reading something about how when you are shocked, the sodium in your blood allows your blood vessels to conduct electricity, and they're usually the path it follows. Cyraan 18:27, 22 January 2007 (UTC)

Crazy Voice

Why does your voice go pitchy and scratchy when you are sick? 216.253.128.27 16:11, 22 January 2007 (UTC)nicholassayshi (UTC)

Perhaps because of an excess buildup of phlegm in your throat, including around your larynx and subsequently, your vocal cords? Chickenflicker---♣ 16:23, 22 January 2007 (UTC)

Laryngitis t h b 02:35, 23 January 2007 (UTC)

References

I am having trouble entering references - especially a reference repeated later in an article. Will be grateful for advice.Osborne 16:43, 22 January 2007 (UTC)

I've never tried to get the hang of the reference templates, or I'd help you out. In any case, you might want to ask this sort of question over at the Wikipedia:Help desk; they're equipped to deal with questions about using Wikipedia tools. Cheers, TenOfAllTrades(talk) 17:07, 22 January 2007 (UTC)

You can find documentation of the referencing system here. --CBD 19:27, 22 January 2007 (UTC)

See Wikipedia:Footnotes. howcheng {chat} 20:28, 22 January 2007 (UTC)

DEBATE HELP ON GLOBAL WARMING

Hi, tomarrow I have a debate in science class and the teacher has just sent the email to letting me know that i am on the team that is against global warming as to say they do not believe in it. Does anyone have any tips for me?? I already have research so please help me in any way possible. Thanx

PS:If you want you could also give me a sample opening against global warming to start off the debate.

Thanks All

Chris —The preceding unsigned comment was added by 80.148.22.236 (talk) 17:50, 22 January 2007 (UTC).

Our article on Global warming controversy should be helpful. Please note, however, that the Scientific opinion on climate change is reasonably unanamous on this issue - there is little scientific doubt that Global warming is taking place - the real controversy is on the causes. You may also wish to review List of scientists opposing global warming consensus. Hipocrite - «Talk» 17:58, 22 January 2007 (UTC)

Whilst this is a very contentious issue you could frame the debate towards the impact on humanity rather than the science debate. It is far too common an angle that the issue is framed as a scientific-issue, when infact it is a political and social problem to overcome. The matter remains a question of how we organise society to react to the changing environment we live in. I would, if asked to do what you are asked, set about showing that the question of global warming's impact on humanity will be indifferent, not negative. I would point towards things that show adaption to environment (for instance in simple terms you could note the widely varying climates humanity thrives in), point towards the development of cleaner technologys and the improved efficiencies of the modern world Vs the industries of previous lives, increasing world wealth and reduced poverty. Global Warming is a big political issue and those who insist on framing it as one without resolution or one that is a matter of fact, when irregardless of science the question of global-warming (in human impact terms) is not classic science but within the realms of political and social sciences. ny156uk 19:01, 22 January 2007 (UTC)

Oh and sorry but you must also note that 'consensus' based science is questionable, particularly on issues that are extremely political such as this (this is not to deny the validity of the scientist's claims but to show that theoretically your side can point to the issues around science as the pursuit of a consensus instead of knowledge). ny156uk 19:04, 22 January 2007 (UTC)

Too bad the other side probably isn't going to do well unless you are at a university. Although I disagree with the... "low" approach, I suggest you follow the established techniques of making it a moral issue rather than a scientific one. I recorded quotes and detailed notes, including time of An Inconvenient Truth:

"There is a consensus of global warming."

"[Skeptics'] objective is to reposition global warming as a theory rather than fact."

(in a video of the Dr. Hanson, dated in the 70s for Congress I believe): "We already know everything we need to know [to stop global warming]"

"This is a moral issue."

Good luck, make sure in your research you look for excellent holdings of both sides in a debate, not just one. Sorry, I thought you were on the other team. I'll reanswer under. X [Mac Davis] (DESK|How's my driving?) 22:03, 22 January 2007 (UTC)

I might be too late, but here is a snippet from an article. [4] I read the whole article, and it basically says that when the earth was in a big cooling cycle from 1940-1970 everybody was screaming that an ice age was coming (and CO2 was still rising!). They came up with extrapolations and pseudo-correlations with sulphates in the atmosphere. Now we are in a warming cycle and the CO2 is still rising. So this article points out that there is a history of extrapolating something that could not be linear. --Zeizmic 22:52, 22 January 2007 (UTC)

You could admit that it's happening, but argue that the resources spent in slowing it down might be better spent elsewhere. Some countries, like Canada, might even benefit from global warming. In that case, their major cities (Toronto, Montreal, Quebec City, Ottawa) aren't on the ocean (with a few exceptions, like Vancouver), so flooding won't be a severe problem. The northern half of Canada is currently arctic tundra, and could become productive farmland. Furthermore, the Northwest passage may become navigable year-round, which could lead to the establishment of major seaports along that route. If you're in Tuvalu, on the other hand, your country will be totally submerged as a result of global warming. StuRat 21:28, 23 January 2007 (UTC)

In that case, I am in favor of using plain old simple facts without any twisting, cutting out, or lying (usually from lack of information). You wouldn't admit that it is happening, because it is happening. The debate that is worth looking at, is how much of it is anthropogenic, and how accurate models are. I know I have probably written far too much information on the subject at the reference desk before, such as here, but I would like to note on Zeizmic's quote that "there is a history of extrapolating something that could not be linear." "could not be linear" is the key phrase here, because delta-CO₂ and delta-T are related logarithmically, not linearly. If you're in the mood to read (you have to be if you don't want to die in the debate, since scientific law states that the skeptic has the "burden of proof") you can read [5][6][7]. It is a terribly difficult debate to win since you have little time, likely most of the voters have already made up their mind, and, "if your side of the debate takes 3 minutes to explain, you'll convince 'em; if it takes 3 hours to explain, you mine as well not spend you time trying." Too bad for us it takes 3 weeks to explain your skepticism. Good luck! X [Mac Davis] (How's my driving?) 04:17, 24 January 2007 (UTC)

Another angle touched on earlier is the social impact. It is not coincidence that the environmental movement and leftist movements are aligned even though there is no nothing that would link the two on their face. A debate angle would be to look at Global Warming as a pretext for political change. For example, Kyoto treaty is based on "carbon credits". This basically creates an exportable commodity for poor nations. It is a form of wealth transfer. The latest (and previous) IPCC reports that espouse the "science" behind global warming are written by political beauracrats, not scientists, and they naturally reflect the political goals of those beauracrats.

And finally the issue comes down to money. Scientists that study events that can doom civilization and destroy life as we know it get a lot of money to investigate what it is and how to stop it. Scientists that investigate a natural phenomena that has been going on for millenia with just gradual effects on civilization don't get a lot money. So it stands to reason that scientists that need money for research will always be studying phenomena that will destroy civilization. THis isn't a slight on scientists, but rather a Darwinian outcome. Scientists that believe Global Warming is a giant, serious problem simply outlive those that don't because they receive plenty of money while the skeptics have to find a different subject if they want to eat. A good read for background is the Authors note in "State of Fear"[8] titled "Why politicized science is dangerous." It is a scary thought that scepticism in science is met with derision especially about such a poorly understand phenomena such as weather. It was only 8 months ago that the climate experts predicted a catastropihic hurricane season in the U.S. due to global warming. In hindsight the scientists now say the catastrophic hurricane season was suppressed by a global warming induced El Nino. They might as well blame voodoo. The thing to look for next is the subtle lexicon change as the average temperature and sea level rise doesn't materialize. It will change from "Global Warming" to "Climate Change" and the hysteria will simply move to weather related catastrophes that are part of our natural, ever changing world. One more thing: Water vapor is by far the most important greenhouse gas. It is not known whether warming will increase cloud cover and reflect more energy into space (cooling phenomenon) or whether the increased water vapor will cause more greenhouse warming (heating effect). This is pretty fundamental since the earth is largely covered by water and water is the largest greenhous gas. All the concentration on man-made CO2 seems a bit overblown when this most fundamental piece of the puzzle is unknown. --Tbeatty 05:19, 24 January 2007 (UTC)

In the US under the Republicans, saying you wanted to study global warming was likely to get your funding cut, since they didn't want to hear about it. I hadn't seen a prediction of a disastrous hurricane season last year due to global warming, what I had heard was that hurricane seasons, on average, would gradually get worse over the next century. That's not the same thing at all. Blips in either direction are to be expected. There may possibly be unknown factors which will kick in to limit global warming, but we haven't seen any evidence of that yet and don't know if they would kick in early enough to prevent drastic climate changes, if they kick in at all. Also, factors that could make things worse, like less reflective ice at the poles and glaciers, will also play a role. StuRat 20:44, 24 January 2007 (UTC)

Not true at all about the funding as it is mostly controlled by bureaucrats. You only have to look at the cover of Al Gore's movie showing a hurricane eminating from a smokestack to see the linkage. The prediction from Scientists was a higher than average season though smaller than 2006. Global warming was cited by many as the reason for higher than normal. Tbeatty 03:05, 25 January 2007 (UTC)

Somebody mixing up weather and climate perhaps? Hm? :) It can get really silly. 72.188.92.255 11:07, 26 January 2007 (UTC)

Strange phenomenon with digital camera

I'm not sure if this belongs here or in Wikipedia:Reference desk/Computing, but I'll try anyway.

I have a Canon PowerShot S3 IS digital camera, and have noticed a strange phenomenon with it. When I'm photographing very bright light sources, they cause a vertical, straight blue line to appear on the LCD display, in a place where the line intersects the light sources. This line is vertical relative to the LCD display itself, not to the physical world - if I rotate the camera, the blue line rotates in the picture. It's only in the LCD display - it does not appear in the actual photograph. What in the world is causing this? JIP | Talk 18:22, 22 January 2007 (UTC)

Same camera, same thing. It's mentioned in the manual, but without an explanation. If I understand the issue correctly, this page explains it as an overload in a pixel on the CCD, which causes it to leak charge into adjacent pixels. I'm not sure why this happens only when viewing on the LCD, but I'm guessing it's because the camera has to take a rapid series of frames, which means it has to accept more light in a shorter period of time, and the anti-blooming might not be fully enabled in order to keep that framerate up. That is a pure guess though, I'd like to hear if anyone with real knowledge can share what's happening. -- Consumed Crustacean (talk) 19:08, 22 January 2007 (UTC)

I am pretty sure you nailed it. The image in the viewfinder or on the back LCD is generated by leaving the shutter on the camera open permanently. This causes a bloom effect since the CCD doesn't have time to discharge between each frame. Since the actual picture is taken by closing the shutter, clearing the CCD, and then snapping the shutter for a very brief period, it avoids this kind of artifact. --66.195.232.121 19:14, 22 January 2007 (UTC)

I have a related problem with an Aiptek Pencam SD. Whenever a bright light such as a headlight or reflection from the sun, etc. is sent toward the lens the remaining video signal sent to the computer turns black and magenta (as in black and white) and is displayed that way on the monitor and written that way to the harddrive. My educated guess is that in this case the overvoltage, voltage saturation or bloom problem is not delt with by the firmwear and rectified only by reset in preparation for the next frame. -- Barringa 19:27, 22 January 2007 (UTC)

Antibiotics question

I was bitten by a Rottweiler yesterday so am now on a course of antibiotics and realised that I have very little idea about how they work, unfortunately the article doesn't help a great deal. I have loads of questions...

• Do the antibiotics move round the body randomly and just bump into bacteria by chance or is there any 'pooling' of antibiotics into the same kind of places that bacteria favour / mulitply ?
• Do antibiotics bind onto the bacteria and kill them and are then 'used up', or do they then fall off and move on to the next bacteria?
• Why can't I take all my antibiotics in one go rather than over a week? Is this to avoid killing off all the 'friendly bacteria' in my body or are there side effects unrelated to bacteria?
• How exact is the targeting of antibiotics i.e. will they only attach onto specific bacteria types or are they continually binding on to the wrong bits of my body and only a few of them 'get through'?
• Does the immune system ignore antibiotics or am I in some way continually processing them to get rid of them?
• Are the answers to all these questions different for each antibiotic?
• Would I know this kind of thing already had I done more biology at school?

thanks, JMiall 18:28, 22 January 2007 (UTC)

A lot of good questions. First off, each antibiotic will behave differently within the human body and at the bacterial target.

1. Absorption of oral antibiotics generally follows drug absorption rules: the molecule size & charge will determine when & where the drug passes into the blood stream. These properties, in addition to passive/active transport and relevant drug metabolism pathways will determine the Distribution (pharmacology) and Clearance (medicine).
2. Antibiotics can work to prevent bacterial protein synthesis, cell wall formation, and a variety of other physiological functions; some even work as a sort of pore that basically punch holes in the bacterial wall. The mechanism of action in the bacterium may or may not inactivate the antibiotic for further attacks. Antibiotics are largely inactivated by our own metabolic pathways, though.
3. In basic pharmacokinetic studies, a therepeutic dose is dtermined for optimal efficacy with limited side effects and toxicity. A single huge dose may overshoot that range and just make you sick while not allowing enough time for the drug to work as directed. Regular, smaller doses will maintain a serum level of the drug over an extended period that will increase the treatment's efficiency while avoiding many of the side effects, which can include killing off your commensal bacteria. -- Scientizzle 19:26, 22 January 2007 (UTC)

There are hundreds of antibiotics in eight major families, if you want info on the one you are using, then you'll have to look it up specifically of ask about it specifically, because the answers to these questions is different for different antibiotics, but to answer your questions in order:

1.Do the antibiotics move round the body randomly and just bump into bacteria by chance or is there any 'pooling' of antibiotics into the same kind of places that bacteria favour / mulitply ?

-The antibiotics pretty much just move around randomly. Most travel in the blood, and thus are only able to travel where the blood travels (thus some can't travel to the csf or to ischemic areas efficiently).

2.Do antibiotics bind onto the bacteria and kill them and are then 'used up', or do they then fall off and move on to the next bacteria?

-most antibiotics kill/stop bacteria by mimicking something the bacterium uses as "food". In this process, the antibiotic is either incorporated into some structure in the bacterium or blocks some enzyme from doing its thing. When/if the bacterium dies, it will most likely be eaten by a phagocyte, which is likely to destroy the antibiotic. Thus they are, for the most part, used up. A non-trivial amount of antibiotic will, however, spontaneously "fall off" the bacteria (before or after it dies) and be recycled.

3.Why can't I take all my antibiotics in one go rather than over a week? Is this to avoid killing off all the 'friendly bacteria' in my body or are there side effects unrelated to bacteria?

-bacteria and human cells are different, but have similar ways of going about things. Thus a lot of antibiotics act on the human analogues to bacterial processes, just to a lesser extent. Another way of saying this is that the human cells are hurt by the antibiotics too, and in the same ways, just not as much. At high doses, however, the damage to human cells can be much more extensive. Some antibiotics also have side-effects unrelated to their antibacterial properties (rifamycins come to mind). Also, getting these chemicals out of your body puts strain on the liver and kidneys, which can be overwhelming in the case of an overdose.

4.How exact is the targeting of antibiotics i.e. will they only attach onto specific bacteria types or are they continually binding on to the wrong bits of my body and only a few of them 'get through'?

-They have very specific targets, which vary depending on antibiotic type.

5.Does the immune system ignore antibiotics or am I in some way continually processing them to get rid of them?

-The immune system usually ignores them, but some antibiotics can cause allergic reactions (indeed, some are likely to). But a different system (usually cytochrome P450) does process to encourage excretion by the kidneys (again, usually).

6.Are the answers to all these questions different for each antibiotic?

-YES, different not just for different chemicals, but also for different modes of administration.

7.Would I know this kind of thing already had I done more biology at school?

-It depends on what level school you are talking about. I majored in microbiology and graduated with a casual knowledge of antibiotics in general (enough to answer these questions, but not much more). it wasn't until med school that I actually learned about how each individual antibiotic functioned. I went to school in the US. Tuckerekcut 22:41, 22 January 2007 (UTC)

Well I went to school in the UK so I suppose I mean A-Level biology rather than university or medical school. Anyway, thanks for the answer, very helpful. JMill 23:19, 22 January 2007 (UTC)

Ask the pharmacist for the package insert for the drugs you're on. Most of these questions are answered there. If not, try the Physicians' Desk Reference. t h b 02:33, 23 January 2007 (UTC)

About that 10-day dose:

Most antibiotics kill almost all of the bacteria after a short time. Usually, you are cured in one day, in the sense that the bacterial population is reduced to a very small percentage of its base in that time is no longer large enough to cause any clinical effect. You spend another day or so recovering, so you are still sick for this time. So why continue with the (sometimes very expensive) antibiotics for ten days? After all, antibiotics have negative effects on your system. There are two related reasons. First, you need to kill off the rest of the bacteria. If you do not, then they can come back after you quit taking the antibiotics. Second, the bacteria that remain after the initial kill-off are the ones that are more resistant to the antibiotic. If you stop taking the antibiotic too soon, the ones that do come back will be harder to kill, and your doctor will need to prescribe another antibiotic. This is why the label tells you to take the antibiotic for the full ten days. Related to this, If you fail to kill off all of the bacteria, then some of these resistant bacteria will end up in the environment and may infect someone else. The cumulatiove effect is to increase the incidence of bacteria that are resistant to that antibiotic. Therefore: Keep taking the antibiotic! If you do not, then you are helping to create a resistant strain, and the first target for the resistant strain is you. So, you keep taking the antibiotic. it kills off most of the bacteria. Your immune system then manages to kill off the rest, achieving a 100% kill, Victory for you, and victory for public health. If you quit taking the antibiotic after 5 days, your immune system will probably eventually win against the residual population, but some of the bacteria may escape into the environment with their resistant genes. -Arch dude

Yes! Thank you for addressing this! One of my pet peeves is when people don't follow the directions that come with antibiotics. This also includes taking antibiotics for viral infections (the flu doesn't need antibiotics, people!) and taking antibiotics that haven't been prescribed for your illness. My sister-in-law drives me insane because she "saves" the remaining pills after she feels better and takes them in the future if she feels ill. She too stubborn to listen to a biologist (me) explain exactly why what she's doing is causing more harm than good... -- Scientizzle 15:59, 23 January 2007 (UTC)

Hydrogen Vehicles on a Mass Transit Scale

It is my understanding that some hydrogen powered cars only give off water as a by-product. Presuming this comes out of an exhaust-system (like current fumes) I am interested in this effect on large roads. If we have roads with 50,000 cars using them per day (no idea if that amount is too high/too low) and each is dropping a small amount of water as discharge (for arguments sake 1ml per mile travelled) will we have high-transit roads that are constantly 'wet' or 'damp/moist'? I'm just interested whether this is plausible or whether i'm expecting far too much discharge and not taking into account other factors. ny156uk 19:09, 22 January 2007 (UTC)

Most likely its evaporation would help keep the pavement cooler. Barringa 19:39, 22 January 2007 (UTC)

Water drips out of the tailpipes of ordinary cars now, as a product of combustion. Edison 21:32, 22 January 2007 (UTC)

Probably only for a few minutes while the tailpipe is cold and you get condensation. Once it heats up you'd just get steam out of either tailpipe, which would never touch the road. StuRat 20:56, 23 January 2007 (UTC)

Water vapor is a larger component of greenhouse gases than carbon dioxide. It seems counterintuitive that Hydrogen powered vehicles would have less of an impact on Global Warming than other combustion based vehicles. --Tbeatty 05:19, 28 January 2007 (UTC)

What kind of wood??

What kind of wood would make a great book cover and book back (instead of cardboard)? Something inexpensive, natural and easy to cut to a size 6 inches by 9 inches by one half (or one third) inch. I don't like plywood because it's too "modern" and artificial. I want something that has a more natural or primitive feel.--142.108.107.36 21:29, 22 January 2007 (UTC)

Balsa is an inexpensive, lightweight wood. Hipocrite - «Talk» 21:30, 22 January 2007 (UTC)

Might be too soft for this purpose. Any kind of pure wood is going to be "natural" compared to a composite_wood like plywood. Friday (talk) 21:33, 22 January 2007 (UTC)

Is there any particular color you're looking for? What sort of budget do you have in mind? User:Zoe|(talk) 21:38, 22 January 2007 (UTC)

Any colour. Something easy to buy in bulk or cut to the appropriate dimensions. Will not fall apart if cut thin. Easy to work with. Inexpensive but still looks OK when sanded/polished.--142.108.107.36 22:03, 22 January 2007 (UTC)

How about cedar? User:Zoe|(talk) 22:30, 22 January 2007 (UTC)

Cedar is a bad idea. It is expensive, brittle, very very slivery, and is unusually sensitive temperature and humidity variations (shrinkage, cracking). It's still my favourite wood tho. ;-) Anchoress 01:14, 23 January 2007 (UTC)

Why not just good ol common pine? It's not the most common building material for no reason. Vespine 01:04, 23 January 2007 (UTC)

I agree with pine, although a finer wood might be nice. Rosewood or ash. I'm a big fan of rock maple, but it would be too difficult to plane yourself. If you could have it cut to the thickness you desire by someone with the right machinery, it would be great. Of course there's also oak, which is very strong and you could even just buy some tongue and groove oak floorboards and trim them to size. Anchoress 01:14, 23 January 2007 (UTC)

Responding to my own post. Reading the Rosewood (timber) article, I'm reminded of something; all the typical musical instrument woods (maple, mahogany, rosewood etc) would be good choices because they are known to be strong even when thinly planed. However, in addition to that, you may be able to get a piece already planed and sanded from a luthier. A scrap or second. It would be cheaper, thinner, and already planed for you. Anchoress 01:17, 23 January 2007 (UTC)

A google for wooden book covers Returns 13 million results, including: [9] [10] [11] [12] -Arch dude 02:08, 23 January 2007 (UTC)

Incendiary laser pointer: Star Wars junior?

An Associated Press story [13] claims that an unattended laser pointer set furnishings in an office on fire. I own a laser pointer and not only does it have a momentary pushbutton to operate it so it could not be left on, but it says "Class IIIa laser product. Max output<5mW." How is it possible for 5 milliwatts from a laser pointer to set something on fire? This one does not even make the skin feel warm if directed at a spot. It would, by definition take 200 seconds to deliver one Joule of energy; how long would that take to raise say a gram of paper or cloth to the point of combustion (Fahrenheit 451?), Are there super powerful laserpointers available? Why? It would be easier for a medical laser used for burning things off tissue to start such a fire, but wouldn't such a device also have a momentary switch to prevent injuries or fires? Edison 21:31, 22 January 2007 (UTC)

Take a look at Wicked Lasers. — Kieff 21:42, 22 January 2007 (UTC)

If you had 100 5mw pointers and focused them on paper with a lens or mirrors would their power combine to form a spot that was heated or lit by 500mw? and if so wouldn't it be a lot cheaper than $5000. (Ponters can be had individually for a dollar.) -- Barringa 21:53, 22 January 2007 (UTC)

"Wicked Lasers" is overpriced and gimmicky - it would be better to buy a laser from a respectable manufacturer. For $5000 you could buy a new 25 W (not mW) CO2 laser. Alternatively, you could build one yourself - look at Sam's laser FAQ, for example. --Philosophus ^T 00:46, 25 January 2007 (UTC)

Let's see, 500 mw. The taillight on my old bicycle uses 0.5 amps at 6 volts, so it is 3 watts, or 6 times the power of the $500 super laser assembly. Yet I have never heard of a trail of incendiary destruction resulting from it. Edison 22:17, 22 January 2007 (UTC)

The article on Lasers and possibly Laser safety may be of use. The important thing to note about lasers is that they're fairly efficient, and they can focus their light into a very small spot. This is like using a magnifying lens to burn a piece of paper; the same amount of light may be falling on the paper overall, but you're taking some of that light and concentrating it on a very small spot. -- Consumed Crustacean (talk) 23:24, 22 January 2007 (UTC)

Note that the article doesn't actually claim that the laser beam started the fire; as with any electrical device, it's possible it simply shorted out and caught fire. Consider lithium batteries...

Atlant 23:54, 22 January 2007 (UTC)

What Bird Is This

I can't seem to find out what kind of bird it is. A parrot of some type? I took the picture in discovery cove in Florida. Please let me know on my talk page. Ard0 ^{(Talk - Contribs)} 21:43, 22 January 2007 (UTC)

It's definitely a lutino bird (note the red eyes and the lack of pigment in the beak), which makes it difficult to determine the species. It's definitely a parrot though. --Kurt Shaped Box 02:19, 23 January 2007 (UTC)

Is a lutino related to an albino ? StuRat 20:49, 23 January 2007 (UTC)

Yeah, as far as I know (I'm surprised that there's no article on it). It's a pigmentation aberration that occurs in some bird species (it's fairly common in pet parrots) that results in a completely yellow bird with red eyes and a pale skin/beak. I'm not really sure of the biological basis behind it - anyone know? --Kurt Shaped Box 22:22, 23 January 2007 (UTC)

Leucism? Found in the See Also section of Albino. Skittle 00:07, 24 January 2007 (UTC)

I added a redirect from lutino to leucism. StuRat 20:10, 24 January 2007 (UTC)

Technically speaking, lutinos are not leucistic, they are instead a type of albino. Albinism results in a lack of melanin (due to a defect in the tyrosinase mediated melanogenesis pathway). In mammals this results in a white appearance (as the only neural crest derived pigment producing cell mammals have is the melanocyte). The situation differs in birds, reptiles and amphibians, however. These animals have other pigments (many birds have yellow carotenoids, for example) and lower vertebrates have a whole range of pigments produced in a number of different chromatophores. So when you get an albino by removing the melanin, the other pigments remain. In the case of lutinos, the albino phenotype is yellow, not white. Leucism is a general term that describes a reduction in pigmentation that is not cell type specific (in other words, leucistic animals will lose all types of pigment, not just melanin). I've changed the redirect accordingly. Rockpocket 22:09, 24 January 2007 (UTC)

sun's energy

what is sun's energy and what does it do?

Are you asking about the energy output of the sun? Not that it means much, but our article on the Sun gives a figure of 3.827×10²⁶ watts. That's quite a few lightbulbs. As to what it does – it doesn't do anything in particular. As far as human interests are concerned, it provides light and heat to all the planets of our solar system. Vranak

"What is the sun's energy?": It is mainly heat created by massive nuclear fusion reactions. "What does it do?": Basically on a fundamental level it radiates away from the sun. Vespine 00:03, 23 January 2007 (UTC)

The part of the Sun's energy that Earth receives is, of course, electromagnetic radiation. --Bowlhover 01:16, 23 January 2007 (UTC)

The sun's energy is the ultimate source of life on this earth. It makes life possible for everything. t h b 02:45, 23 January 2007 (UTC)

The first thing I think of when I see that question is the radiation budget.[14][15] X [Mac Davis] (DESK|How's my driving?) 16:22, 23 January 2007 (UTC)

time

Is it true that the passage of time is not absolute, but relative? We all know, of course, that if some omnipotent being (God, a kid with a super-genie who owes him a favour, what have you) decides to move EVERYTHING in the universe "five feet to the left", no-one would be able to tell. If the same made doubled the size of EVERYTHING (the size of atoms, the spaces between, the forces acting on them etc) it would similarly be undectable, right?

Now, what happens if someone decides to speed up or slow down EVERYTHING in the universe. By everything, I mean all processes in the universe. Before, it took 2 seconds to move a certain distance, now it takes 1. A certain chemical reaction used to take 14 miliseconds, now it takes 7. The speed of light is not the same anymore, etc etc.

Would anyone be able to notice?

Duomillia 23:58, 22 January 2007 (UTC)

No, nobody would notice anything. All the (now slower) clocks would still record the same times as they used to for all (now slower) phenomena. It is debatable whether such a change is even conceptually meaningful, that is, whether there is any sense in which anything would in fact have changed. --169.230.94.21 00:59, 23 January 2007 (UTC)

Well and when you consider omnipotence as a possibility then you might as well throw any real scientific understanding out of the window. If an omnipotent being wanted to turn everyone into a rabbit without them knowing, it could do it (ergo the definition of omnipotence).--24.147.86.187 01:28, 23 January 2007 (UTC)

Variable speed of light looks like a helpful article. Melchoir 02:20, 23 January 2007 (UTC)

True, but could an omnipotent being turn him/her self into a rabbit without realising it? Duomillia 02:24, 23 January 2007 (UTC)

The question is incoherent (and more philosophical than scientific). If 'an omnipotent being' (hereafter referred to as 'God' for brevity) could rabbit-himself without knowing it, arguably he wouldn't be all-knowing, and thus cannot be God, for God by definition knows everything. But if he can't do it, he's not all powerful, and thus not God either. Thus you can see that this is simply a variant of the can God make a square circle question.--inks^T 02:54, 23 January 2007 (UTC)

Does that question boil down to, is "God" capable of surrendering his omnipotence? Duomillia 03:00, 23 January 2007 (UTC)

I don't think so (but that's just my take on the matter). The former is "can God do X", where X is a logical impossibility, and that's the problem. To me, this question is not incoherent and is quite different to the original. Presumably once he's renounced his power he is no longer God and can't get it back again, it would be a one-way street. --inks^T 04:19, 23 January 2007 (UTC)

I would notice it. t h b 02:44, 23 January 2007 (UTC)

Unlike a remote part of space it is doubtful that God or your genie can change the past. Without the ability to change the past any change in rate of change, etc. could be compared and noticed now. -- Barringa 04:11, 23 January 2007 (UTC)

The only way to perceive a full scale delta t would be to observe time from outside time. But if you say that you're already outside the realm of science and into "speculation." 16:17, 23 January 2007 (UTC)