Wikipedia:Reference desk/Archives/Science/2007 August 28

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August 28

When is the best time to change gear in a manual car?

In the question Wikipedia:Reference_desk/Archives/Miscellaneous/2007_August_18#transmissin_output_torque_.3D_engine_power, User:SteveBaker talked about obtaining the best 0-60 time in his Mini Cooper S by shifting to keep the engine at it highest torque output. I notice SteveBaker answers alot of questions on the reference desk so I have been reluctant to ask, but I can't work it out for myself -- Why is gearing ignored in his answer?

For example, I created some tables using these gear ratios I found on the net for a Mini Cooper S:

1st Gear 11.450
2nd Gear 7.181
3rd Gear 5.397
4th Gear 4.407
5th Gear 3.656
6th Gear 2.986

According to the graph he linked, in first gear the engine at 5500 RPM would be creating 150 ft-lbs of torque and turning the wheels at around 480.35 RPM (5500 RPM / 11.45) with 1717.5 ft-lbs of torque (150 ft-lbs * 11.45). If we shifted up now, the engine would be running at 3449.39 RPM (480.35 RPM * 7.181) and producing still around 150 ft-lbs of torque but our torque at the wheels has dropped to 1077.15 (150 ft-lbs * 7.181). Had we have stayed in first gear to nearer the redline, say 6500 RPM we would have been making only 140 ft-lbs at the engine but 1603 ft-lbs (140 ft-lbs * 11.45) at the wheels.

Help! Where am I going wrong?

Alan 78.32.138.240 00:12, 28 August 2007 (UTC)

I think what you say sounds good. As far as I can tell, you are correct. —Bromskloss 06:31, 28 August 2007 (UTC)

What you are missing is that if you stay in 1st gear for longer than I would, your torque in 1st is dropping rapidly as the RPM's increase - so whilst you'd be getting more torque in 2nd after you shift at redline, you'll have lost ground over someone who shifted earlier. SteveBaker 11:47, 28 August 2007 (UTC)

By my basic understanding, acceleration is determined by force at the wheels, force at the wheels is given by engine torque * gear ratio. Even if torque dropped to 130 ft-lbs at the flywheel, 130 * 11.450 is still more then 150 ft-lbs * 7.181. Maybe my confusion is coming from the use of the word torque for both "flywheel torque" and "driving wheels torque". Also see [1] which is linked from the article on Torque, specifically the section "A Simple Example" where he shows that by changing from 3rd to 2nd even though he produces less flywheel torque, it results in more force at the wheels. Alan. 78.32.138.240 12:29, 28 August 2007 (UTC)

Really? Decreasing torque as a result of staying in gear is OK, if shifting would have given you even less torque. (I assume shifting is instantaneous, as I believe we all do.) —Bromskloss 12:01, 28 August 2007 (UTC)

mathematically speaking: plot rear wheel torque vs car speed in all gears. you will get a bunch of peaks, one for each gear; but what's important is where the descending tail end of each gear crosses the ascending front end of the next gear. obviously, that's the shift point, in mph. in real life, you have to allow for a drop in rpms while shifting, so run it a bit higher. Gzuckier 15:57, 28 August 2007 (UTC)

That is exactly what I did and from 0-60 I can see no point where the Mini Cooper S generates more torque at the wheels in a higher gear (lower ratio) before hitting the redline. I am admitedly very much a beginner when it comes to automotive engineering but my theory is that, as the Cooper S is supercharged it has a very flat torque curve through-out the RPM range much like a naturally aspirated engine with a higher displacement - coupled with it's wide gear ratio means the curves do not overlap. Although if SteveBaker has had his Mini Cooper S on a drag strip I cannot argue with empirical evidence. Alan. 78.32.138.240 16:50, 28 August 2007 (UTC)

For 'drag strip' read 'nice, level, deserted freeway on-ramp'! I used an accellerometer to measure 0-60 times. Please bear in mind that mine is not a 'normal' MINI Cooper'S - its got a bunch of 'go faster' stuff, so my torque curve doesn't look like the one in that article. Also, in practice, an awful lot depends on how fast/smoothely you shift and how quickly the engine will drop RPMs as you shift - and (not least) whether you can keep a close enough eye on the tachometer while remaining on the road! It took months of practice and a computer program that I wrote to simulate the entire process in order to get the best 0-60 time out of my car - and without an accellerometer, you can't measure your times accurately enough to know whether you are getting better. SteveBaker 19:02, 28 August 2007 (UTC)

For what it's worth, I've used an accelerometer (A Perfmeter Pro I think it was called), but I'm not sure I have a lot of confidence in their accuracy. The one I used depended on being perfectly level when the car is sitting there. But, a hard launch will jerk it around, possible causing it to move off-level, which could skew results for that run. I suppose as long as you confirm that it's still level once you've stopped, maybe this problem is reduced. But, to my knowledge, car magazines for example don't depend on such devices, presumably because they're willing to put in the cost and effort for more accurate means of measurement. But, maybe a typical accelerometer is plenty accurate for casual usage as long as it's used correctly. Mine was pretty easy to use incorrectly, tho. Friday (talk) 19:08, 28 August 2007 (UTC)

Mine's a G-Tech Pro - it compensates for being level because you tell it when you are stationary and it measures it's slope at that point. It seems to survive the worst jerks I can give it with my MINI - it beeps when it thinks you're at 60mph - and that agrees well with my GPS's speed estimate (but not with the car speedometer - which like most cars is deliberately off by a couple of mph). But in any case, I'm not looking for absolute numbers - just "did I do better than yesterday", and since I used this same freeway on-ramp (on my way to work after dropping my kid off at school - every day for many months) - all of the slope issues and other variables ought to cancel out. The things that don't cancel out are things like ambient air temperature (which affects the car's performance noticably) and the amount of gas in the gas tank (which is a not-inconsiderable weight difference in such a light car as the MINI). SteveBaker 21:24, 28 August 2007 (UTC)

katydids/diet

Your entry on katydids reports that larger, predatorial katydids have been known to eat small children. This is a joke, yes? My son, Andrew, is worried. Thanks for your clarification. —Preceding unsigned comment added by 72.133.249.135 (talk) 03:31, August 28, 2007 (UTC)

That was vandalism. Interestingly enough, added by an IP address registered in Wisconsin, same as yours! Someguy1221 03:51, 28 August 2007 (UTC)

It is ashame that someone would alegedly lible a reputable person, did they think it was funny, or a joke, "yes"., I don't find it funny.--Aaron hart 14:29, 28 August 2007 (UTC)

Apparently, not a lot of people think about the consequences of their actions, unfortunately. x42bn6 Talk Mess 15:44, 28 August 2007 (UTC)

Laser

So, we've all heard of those handheld green laser pointers that can burn through paper, but would shining a "normal" laser pointer through a telescope of magnificvating glass make it as powerfull (ya know, like when you do it with the sun?) 82.198.250.72 14:55, 28 August 2007 (UTC) 82.198.250.72 14:55, 28 August 2007 (UTC)

Probably not : a lens focuses the rays from the sun onto a point - but in the case of a laser there is really only one ray. That single ray does have width however so it will be possible to concentrate the narrow cylinder of light onto a point - in fact people have done this - creating flashes at the focus point (in air) where the atoms or whatever are heated very hot and ionised.87.102.90.8 15:16, 28 August 2007 (UTC)

I've never heard of this being done with a normal laser pointer (1mW) but it might be possible if focused enough. If you want to do this, you'll have to widen a lot your beam (because otherwise you'll be limited by diffraction) and then refocus it. Then, you'll have problems with the quality of your optics. You can't make your calculations with ray optics, you at least have to consider gaussian beams optics or a full simulation taking into account diffraction. It's difficult to focus much narrower than 1 micron^2. Might be easier with a green pointer of equivalent continuous power because those ones are pulsed (passive Q-switch) so it interacts a bit differently with matter. --81.67.15.32 18:09, 28 August 2007 (UTC)

In my optics lab we used lenses to focus lasers very similar to those laser pointers (the only difference was that ours were more coherent) into fiber-optic systems. The typical width of a laser from such a pointer is 1 mm, but fiber optic wires we used were about 10 micrometers wide. The Gaussian nature alone prevented us from making it much smaller than a few micrometers wide, though. Someguy1221 03:00, 29 August 2007 (UTC)

XRF Bremsstrahlung Shape

I've done my homework on the wikipedia X-Ray Fluorescence Spectroscopy and Bremsstrahlung articles, as well as some others, but I can't seem to find any sort of equation for the Bremsstrahlung itself. I don't care how many parameters it calls upon -- I just need to find some sort of legitimate baseline that works better than a basic interpolation fit. Any ideas? 146.139.76.94 14:06, 29 August 2007 (UTC)

http://rkb.home.cern.ch/rkb/PH14pp/node16.html (any good? - didn't check!)87.102.90.8 16:16, 28 August 2007 (UTC)

Have you tried searching the web itself for "Bremsstrahlung" already?87.102.90.8 16:17, 28 August 2007 (UTC)

I appreciate the link - although I can't seem to get a fittable equation out of the one in integral format. I've tried googling a range of related search topics, but none of the results actually show how the background Bremsstrahlung was fitted. 146.139.76.94 14:06, 29 August 2007 (UTC)

I'm afraid I don't understand/can't explain bremsstrahlung fully, and nobody else here seems to be clued up on it..

In the link I gave - it seemed to cover bremsstrahlung for an electron in an atomic field - this is the behaviour you are asking about I hope..

Assuming the link was in the right subject area but not detailed enough maybe the maths desk could help you more?

You said "I just need to find some sort of legitimate baseline that works better than a basic interpolation fit" - did that mean you want an expression for the whole spectra, or do you just need a relationship between highest bremsstrahlung energy and electron X-ray energy (latter is much easier)

I'll try to help further if you wish. though I'm currently confused how conservation of spin (selection rules) can be made to fit with the spectra obtained..If you can explain that to me I might be able to have a go at deriving the equation myself for you. ("Hope Springs Eternal")87.102.18.14 14:39, 29 August 2007 (UTC)

I'm guessing that you have a real spectra and need a theoretical bremsstrahlung curve so that you can subtract it to get a clean baseline...?87.102.18.14 14:43, 29 August 2007 (UTC) (Note - if you are doing x-ray fluoresence won't you be measuring the electron energy and not bremstrallung photon energy? - though the two are closely related)

By the way it's possible to quite easily remove the bremsstrahlung hump without knowing its equation using simple analysis (on a computer) - and just leaving the peaks on a flat baseline - maybe this is all you need?87.102.18.14 15:51, 29 August 2007 (UTC)

Area of Earth one can see.

Just say I were in the middle of a flat ocean, and I look 360 degrees around myself, how much of the surface area of the earth will I be able to see as a percentage of the total area of earth, and as just a figure? Assuming perfect vision. Phgao 15:44, 28 August 2007 (UTC)

The horizon article is a good place to start. If you know the distance you can see, you can figure out the area of the sphere within that distance. The Mathematics Desk might be a better place to discuss the details of these geometrical calculations. DMacks 16:00, 28 August 2007 (UTC)

(ec)According to Horizon#Distance_to_the_horizon, the true horizon is only 4.7 km away for a person 1.7 m tall. (You may be able to see farther due to refraction dependent upon atmospheric conditions.) Thus you can see an area of 69.4 km². The surface area of the earth is 510,065,600 km². Percentage-wise that's tiny: 1.37 x 10^-5 %. -- Flyguy649 ^talk _contribs 16:02, 28 August 2007 (UTC)

For a perfectly spherical earth, I think the answer is exactly ${\tfrac {h}{2(R+h)}}$, where R is the radius of the earth and h is the height of your eye above the surface. This agrees with Flyguy649's number for the special case of h = 1.7 m. -- BenRG 16:25, 28 August 2007 (UTC)

BenRG messed up somehow - that can't be the right answer - if you increase R, the distance you can see gets smaller - that's not right. When I plug in the numbers, I wind up with about 1 micron as the distance to the horizon!! SteveBaker 18:51, 28 August 2007 (UTC)

The area you see increases, but the fraction of the total area decreases. BenRG's answer is dimensionless, so it could never have been the area itself. —Bromskloss 19:10, 28 August 2007 (UTC)

OH! I see, sorry I didn't realise BenRG was talking about the ratio of the area. That makes sense. My bad! SteveBaker 21:07, 28 August 2007 (UTC)

Now wait here. I'm getting something else. Did you neglect the curvature of the Earth at some point? —Bromskloss 17:59, 28 August 2007 (UTC)

Hmmm - let's derive this from first principles: Imagine a right triangle - one vertex at the center of the earth (C), another where your eye is (E), the third where your line of sight hits the horizon (H) where it is a tangent to the surface of the earth. The angle C-H-E is a right angle (because E-H is a tangent). The distance you can see is given by Pythagoras: (R+h)²=d²+R² (where 'd' is the distance you can see, 'R' is the radius of the earth and 'h' is the height of your eye above the surface of the earth). Rearranging, I get: d = sqrt((R+h)²-R²) which you can multiply out to give: d=sqrt(h²+2Rh) - Some people drop the h² part because it's negligable compared to 2Rh, so you wind up with d=sqrt(2Rh) - which is a reasonable approximation for small values of h. SteveBaker 18:43, 28 August 2007 (UTC)

(And plugging in the numbers - I get 4.656km for a 1.7m eye height - which is in good agreement with Flyguy649's answer). SteveBaker —Preceding unsigned comment added by SteveBaker (talk • contribs) 18:48, August 28, 2007 (UTC)

Sorry, I was wrong. I did it over again, and got exactly the same as BenRG, without any approximations. The area seen is $2\pi R^{2}h/(R+h)$, and if you divide by the area of the whole Earth ($4\pi R^{2}$) you get $h/(2(R+h))$. —Bromskloss 19:06, 28 August 2007 (UTC)

So you could see someone else of that height at almost 10 km away in the eye - assuming perfect vision. DirkvdM 06:13, 29 August 2007 (UTC)

How much of a difference does atmospheric refraction make? Could you see more of the earth if you were in a big desert (a hot one) than if you were at the antarctic (due to temperature gradients)? How much more? Capuchin 06:55, 29 August 2007 (UTC)

Yes - refraction through the air does extend the distance you can theoretically see by a small amount. Exactly at the horizon there is a deflection of about a half degree (at sunset, for example, when the bottom edge of the sun touches the horizon, in reality the sun is almost completely below the horizon and you can only see it because of diffraction). Translating this into extra distance is kinda tricky - but the difference isn't great. You can see a teeny-bit further at the poles than at the equator because the earth isn't quite spherical...but again, the effect is negligable. It's rather pointless to figure all of these subtle effects into the equation because you never have sufficiently perfect conditions for these things to matter - at sea, you are bobbing up and down - so your estimation of eye height is not accurate. On land, the ground is never flat enough for these calculations to have real meaning. The numbers we've already given are plenty good enough! SteveBaker 14:41, 29 August 2007 (UTC)

Pointless but interesting :) Capuchin 14:59, 29 August 2007 (UTC)

Hardly pointless! International treaties have been made and broken over such details as "how far into the ocean can I see from my watchtower?". How far from the coast is international water? Were these guys in sight of land or not? Modern GPS surely doesn't eliminate the problem, or else such incidents would easily be settled by consulting a hand-held display and pleasantly agreeing on coordinates. Nimur 17:02, 29 August 2007 (UTC)

Gull feathers - do they make better duvet filling than duck/goose/chicken feathers?

I was told this today by someone who used to make feather duvets. I don't know if she was joking or not but apparently, seagull feathers make the warmest duvet fillings of all - better than eiderdown. The only downside is that they're hard to gather and expensive (thinking about it, gulls have very thick coats, don't they?). Anyone have more info? I know some of the gull people here will be interested in this. --90.240.209.98 15:45, 28 August 2007 (UTC)

Generally down is better than feathers (in terms of warmness) I believe..You must have meant seagul down?87.102.90.8 16:24, 28 August 2007 (UTC)

Question - can it really be any better than any other 100% down filling?87.102.90.8 16:29, 28 August 2007 (UTC)

Good question. I wonder if the down of the gulls of the high Arctic (e.g. the Glaucous Gull) has superior insulating properties? Gulls are generally *very* hardy birds, so maybe there's something to it. Heh, I wonder if a penguin down duvet would be any good? --Kurt Shaped Box 16:37, 28 August 2007 (UTC)

It's possible, but you would need to research which particular species of gull, and you would need an awful lot of them. I've no doubt penguin down is also an excellent insulator when supplemented with a layer of fat.--Shantavira|^{feed me} 17:42, 28 August 2007 (UTC)

The person tasked with collecting the gull down has my deepest sympathy. They should get those bear bile guys to do it. --Kurt Shaped Box 21:50, 28 August 2007 (UTC)

experiment to determine planck's constant

hi

can someone suggest an experiment to determine planck's constant (apart from the common photoelectric effect one)? thanks. —Preceding unsigned comment added by 202.63.233.12 (talk) 15:54, August 28, 2007 (UTC)

Seaching the web for "planck constant determination" throws up several different methods eg http://ww.google.co.uk/search?q=planck+constant+determination&hl=en87.102.90.8 16:22, 28 August 2007 (UTC)

ANTI-GRAVITY WORKSPACE

This question is really aimed I guess for an Astronaut, being that they are a well documented breed of workhorse, I'm going to assume there is a wiki-individual that knows something to the matter. ?Being in an Anti-Gravity environ, the lack of stress on the body, what types of effects does this have on the mindframe of a worker?(can they work longer than 8 hours? is time an issue? on time off, do you still work just to do something? how much sleep is needed? who evaluates fatigue?) In the same sense of T.H.White's explanations on how things came to be from observations in the wild kingdom. I'm going to theorize the pressures of the battle regalia of Samurai/Knight class warriors. Pressures stressed on body, flare up a driving force to focus intently on whatever it is you are doing. Like all the mail a knight would have to wear, and his visibility from helmet visor, and/or Samurai scary mask, covers much of the face and vision., and yet the extreme warrior gets the job done. Or the today's and Victorian English Gentleman and Gentlewomen, with the extreme stresses on body with tight corsets and neckties. Putting pressure on a human body, the physical part, does in fact amplify the mental performance. And yet, the exact reverse, no pressure at all., hence my question on anti-gravity. This may fall under the catagory of Corporate Mass Psychology, there's a term for that, I just forgot what it was. Thank you. 216.100.216.5 16:57, 28 August 2007 (UTC)Jacob V

I've tried to parse your stream-of-consciousness "question", and have a couple comments. 1.) Astronauts work in zero (or near-zero) gravity, not Anti-gravity. 2.) Anti-gravity doesn't actually exist outside of theory and science fiction. 3.) The psychophysical problems with living in the Weightlessness article. -- JSBillings 17:23, 28 August 2007 (UTC)

Strictly, it's not even 'zero g' - there is almost as much gravity up there as there is down here. The correct term is 'free fall'. Astronauts and the craft they are in is falling - hence they don't FEEL the gravity. But it's definitely still there! The only time humans have truly experienced zero g was during the moon shots when the astronauts were at the exact point between earth and moon where the two gravity wells cancelled out...and even then, they were experiencing the force of gravity from the sun. SteveBaker 18:26, 28 August 2007 (UTC)

I would suggest also that the notion of encumbrance increasing effectiveness is flawed, at least as presented. A suit of armor doesn't make someone a better swordsman, it just makes him harder to kill. Additionally, much of the encumbrance you mention (such as corsets and neckties) contributes no meaningful weight, which is the only change when moving to weightlessness. A suit of armor is still incredibly restrictive when weightless -- just look at spacesuits! — Lomn 18:18, 28 August 2007 (UTC)

Plus, a lack of gravity does not negate mass's inertia. So, if you're wearing a half-ton suit of armor in space, you still need to be strong enough to get it moving and to slow it down, move your arms and legs. -- JSBillings 18:24, 28 August 2007 (UTC)

Our bodies evolved to work efficiently at 1g. I would expect there to be in almost all cases some deterioration to functions in any other environment without artificial support. Capuchin 07:40, 29 August 2007 (UTC)

As far as ability to work goes, microgravity is far better than no gravity. Microgravity makes heavy things easier to lift (although inertia does become an issue with really heavy items), but doesn't cause the annoyances of zero gravity, like not being able to walk and having your tools float away when you set them "down". While inertia can be overcome by moving massive objects extremely slowly, at some point it becomes too slow to be practical. StuRat 04:48, 30 August 2007 (UTC)

I remember a scene in fiction where a man annoyed by a cat picked it up and placed it high in the middle of the room, where, thanks to microgravity, it would take twenty minutes to hit the floor. The cat, having been subjected to this treatment before, resigned itself and took a nap. Anyone know what story that was? —Tamfang 07:29, 2 September 2007 (UTC)

Sounds like a good story (that would have to be like 1 millionth of a g). StuRat 02:15, 3 September 2007 (UTC)

White House

Why is it called white house? Is it because they only allow white presidents? 211.28.78.74 18:02, 28 August 2007 (UTC)

Read the article White House before making ridiculous assumptions. -- Kainaw^(what?) 18:05, 28 August 2007 (UTC)

that article is incomplete. just says http://wiki.riteme.site/wiki/White_House#Naming_conventions which says nothing about the origins of name?

The article states (under Naming Conventions): "...it is also speculated that the name of the traditional home of the President of the United States may have derived from Martha Custis Washington's home, White House Plantation in New Kent County, Virginia...". It is my opinion that that is SOMETHING about the origins of the name. -- Kainaw^(what?) 18:14, 28 August 2007 (UTC)

Yes i did read that part, but it is speculation, which shouldnot be in there. You should remove it. I want to know the truth, what is the real reason. Why would you call it "white" house? Has it got to do with American Foreign Policy? 211.28.78.74 18:26, 28 August 2007 (UTC)

The phrase in the article is properly cited and there is no need to remove it. You are correct that speculation on the part of Wikipedia editors shouldn't be in articles, but this is not an example of such speculation. There is no conspiracy or secret agenda behind the naming of the White House. — Lomn 19:38, 28 August 2007 (UTC)

Given that when it was named, only whites were allowed to vote anyways, they would see no need to point this out. It is like referring to it as the "Human Palace" on the off chance great apes get the vote some day. Eran of Arcadia 19:53, 28 August 2007 (UTC)

Just a minor point of politeness -- I know you probably didn't intend it, but the analogy comparing Whites::Nonwhites and Humans::Apes is somewhat offensive. -- JSBillings 20:07, 28 August 2007 (UTC)

It seems fairly clear that Eran was refering to how people perceived things at the time, not how things actually are. Skittle 14:05, 29 August 2007 (UTC)

(de-indent) Not true, strictly speaking. While race was abolished as a condition for suffrage in 1870, many states permitted multiracial voting from inception. — Lomn 20:05, 28 August 2007 (UTC)

But don't forget the poll tax though Nil Einne 20:20, 28 August 2007 (UTC)

There were plenty of voting restrictions to be sure. However, "only whites were allowed to vote anyway" is flat-out false. — Lomn 20:47, 28 August 2007 (UTC)

After reading the article, it seems that they called it the "White House" just as another name amongst others, such as the "President's Castle", even before it was burned to the ground and rebuilt. Could it possibly be that it was called the "White House" because.... it was painted white? -- JSBillings 20:13, 28 August 2007 (UTC)

That question is as absurd as asking "Why is the Casa Rosada called like that? Is it because they only allow pink presidents?" Titoxd^{(?!? - cool stuff)} 20:15, 28 August 2007 (UTC)

While I'm not challenging the idea the question is absurd, to be fair no one ever really called themselves pink AFAIK (ever if many people are more accurately called pink then anything else) whereas people did and do call themselves white. So it's not really the same thing IMHO (but reread the first part of my response). Nil Einne 20:23, 28 August 2007 (UTC)

Yeah, but the original question was gasping at straws to make a political statement out of an insignificant fact... Titoxd^{(?!? - cool stuff)} 22:55, 28 August 2007 (UTC)

This question doesn't really have anything to do with science does it Nil Einne 20:24, 28 August 2007 (UTC)

The "urban legend" of its name [2] went that after the British burned it in 1814, it was stained black from the soot, and after it was rebuilt, it had to be painted white, so it came to be called the "white house." In truth, the stone it was built from was porous and tended to absorb moisture and spall during freeze-thaw cycles, so the exterior was painted white from the day it was built. Furthermore, after the celebrated burning, it was demolished down to the basement level except for parts of the south face, and rebuilt with new stone. It was first officially called the "White House" on presidential stationary during the Theodore Roosevelt presidency. Edison 02:00, 29 August 2007 (UTC)

It's a house. It's white. DirkvdM 06:14, 29 August 2007 (UTC)

One might go so far as to make the political interpretation that it is a house and not a palace because America is a Republic with a President, not an aristocracy with a monarch. Our presidents are private citizen and they live in a house. Nimur 17:20, 29 August 2007 (U

Wasn't it originally called the Presidential Palace? —Tamfang 07:26, 2 September 2007 (UTC)

I think I agree to what Edison explained on how the "White House" name came about. By the way, Presidents are public personalities because they are public servants.

Yes, and many, including the current President, have thoroughly serviced both the US electorate and the world at large. StuRat 04:37, 30 August 2007 (UTC)

I don't think any more political statements are needed after the troll's initial question, but... please leave it to the "world at large" to decide whether they feel "thoroughly serviced"... --Ibn Battuta 23:24, 30 August 2007 (UTC)

Many have been. Whether they liked it is a different matter. DirkvdM 06:25, 31 August 2007 (UTC)

Does ice conduct electricity?

I ask because I work at a facility which has just purchased an AED. When using an AED, the victim must not be in a puddle, and must have as dry a chest as is possible. Our policy also includes moving victims off ice (we have an ice rink), which seems ridiculous if ice doesn't conduct electricity. – Mike.lifeguard | ^talk 19:50, 28 August 2007 (UTC)

But the thin film of water that forms when you place your feet over the ice, due to conduction and radiation, does conduct electric charges. Titoxd^{(?!? - cool stuff)} 20:17, 28 August 2007 (UTC)

Neither pure ice nor pure water conduct electricity very well - it's the stuff in the water that changes that:

• Ultra pure water: 5 x 10^-6 S/m
• Drinking water: 0.005 – 0.05 S/m
• Sea water: 5 S/m
• Ice: 6x10^-6 S/m

But ice is weird stuff and it conducts across surface defects rather than through the bulk of the stuff. Weird. SteveBaker 21:02, 28 August 2007 (UTC)

Unidentified Fixed Object

This

Can anyone tell me what this is?

I saw this thing under a light microscope at low magnification (something like 100X if I remember correctly). Some background if it helps: My friend and I were preparing a karyotype for fun. I collected some of his blood, went through the whole procedure, and I came across this thing on one of the slides. —LestatdeLioncourt 21:24, 28 August 2007 (UTC)

It looks vaguely like the cellulose skeleton of a plant cell wall but that is a guess. Graeme Bartlett 22:50, 28 August 2007 (UTC)

Well, it seems awfully hard to believe - but it looks suspiciously like a Stent of some kind. Quite how you'd manage to extract one from someone's blood stream is kinda hard to imagine. If that's correct then whoever you yanked this out of REALLY needs to seek medical help ASAP! SteveBaker 22:51, 28 August 2007 (UTC)

I agree that it looks man-made (like a stent). I would blame contamination from lab materials before assuming that something came out of your friend's bloodstream. -- Kainaw^(what?) 23:01, 28 August 2007 (UTC)

Can you estimate the size and describe the shape more? How does it appear to you when you fiddle with the focus? just describe anything that might not be obvious from the picture. -- Diletante 00:52, 29 August 2007 (UTC)

I'm not sure about the size, but if it helps those little dots here and there are T lymphocytes. By the way, I'm leaning towards the contamination theory; I don't really think this was acutally there in his blood. I'd just like to know what it could be. Aren't stents too big? I don't know if anyone noticed, but I find its membrane's pattern very interesting (you can see it most clearly on the right side). —LestatdeLioncourt 06:32, 29 August 2007 (UTC)~

It's really not clear from the description exactly how big this thing is. If that's a 100x magnified image and those dots are lymphocytes then this thing would have to be a fraction of a millimeter across - so I guess my stent suggestion is not it. It sure looks artificial though - but maybe there is some kind of natural structure that looks like this. Weird. SteveBaker 14:25, 29 August 2007 (UTC)

It looks vaguely diatomish to me. DuncanHill 19:25, 29 August 2007 (UTC)

I'd like y'alls to really work on this one more. You've got me wondering. If a Diatom of some sort, how does it live in the bloodsystem? t-cells, on attack? Could it be some sort of metalic crystalisation of sodiom of sorts? Or again the plant theory?-some bacteria of sorts? Come on people! bear down. Ask a scientist! --Jacob Vi am the kwisatz haderach 21:16, 29 August 2007 (UTC) —Preceding unsigned comment added by Specialagent777 (talk • contribs)

If this was "for fun," then what was your lab procedure? If you are working with a set of slides or cover slips that had previoiusly been used for diatoms and not scrupuluosly cleaned, or on a bench that was contaminated, or in a labe with some dust fo the right sort, this object might have gotten into you sample. My swimming pool filter uses "diatomaceous earth," which is essentially finely ground chalk and which (I guess) may have such structures in it. -Arch dude 00:10, 30 August 2007 (UTC)

Well the first part of the procedure (culturing) was carried out in an aseptic environment (it had better be, cuz it was in a blood-drawing room), but later on (centrifugation, hypotonic treatment, fixation, etc...) the chances of outside contamination was very high, because we were working in the same compartment that they were doing all the bacterial cultures in. The lab technician who was there said he hadn't seen anything like it in his 15 years of lab work, so I doubt it was due to contamination from the compartment we were working in. The slides were also brand new and previously chilled in a sterile cup. —LestatdeLioncourt 22:18, 30 August 2007 (UTC)

If you were 'shooting up' 'bad drugs' the 'product' might be 'tamped' with some 'white stuff' eg chalk - but then you'd know if you were doing that wouldn't you.. Seriously though (I HOPE) The probability of external diatom contamination is quite high - if for instance you - "use a lot of chalk"..87.102.14.233 08:27, 30 August 2007 (UTC)

Another suggestion is that it is the wing off an insect, perhaps a mosquito or fly. It is broken off on the lower end and complete on the upper rounded side. Initially I thought it must have been a cut out piece of seagull feather, but the line around the edge argues against this. Diatom occurred to me, but its nothing like the diatoms I have seen, that tend to have spikes on them. Graeme Bartlett 10:51, 30 August 2007 (UTC)

It doesn't look at all like a fly wing. (I've looked at very, very many!) At high mag, they have a regular pattern of "hairs" that all point in the same direction. And epithelial cells in general are hexagonal in shape (to maximize cell-cell contacts). Flyguy649 ^talk _contribs 13:58, 30 August 2007 (UTC)

Another thing is skin (reminds me of snake skin) - what exactly is the length of this thing? —Preceding unsigned comment added by 87.102.14.233 (talk) 11:11, August 30, 2007 (UTC) Also too big, plus (above) diatoms don't have seems (or do they?)87.102.14.233 11:14, 30 August 2007 (UTC)

The idea that it is a wing or scale appears to me to be based on the idea that the object is flat. The bad focus on the lower left and upper right indicate to me that this is more of a tube than a flat object. It isn't really even a round tube. It has rather sharp corners, making it rectangular. The roundness of the top isn't very round if you follow the edges up to it. It is nearly squared off as well - just appearing rounded due to the lost focus. -- Kainaw^(what?) 13:22, 30 August 2007 (UTC)

Could it be a thread or a bit of gauze? Some type of cotton fiber?--69.118.235.97 15:43, 30 August 2007 (UTC)

If you look very close it seems that it is woven, and that threads approach the edge from behind wrap around and continue to be woven. Could this possble be some new kind of blown celluloce cigarete filter???--Aaron hart 03:50, 31 August 2007 (UTC)

You know you need to quit...when you have cigarettes floating in your blood. Someguy1221 03:53, 31 August 2007 (UTC)