Wikipedia:Reference desk/Science

March 18

Thyroid Hormones

Why are thyroid hormones not used for weight loss in people with normal thyroid function? If one takes synthroid or cytomel, would that permanently effect his/her own production of thyroid hormones even after discontinuation of the pills(synthroid or cytomel)?

The main reason is that thyroid hormones are cardiotoxic -- they severely damage the heart. One of their effects is to enhance the body's sensitivity to the sympathetic nervous system. In doing so, the heart rate increases, predisposing individuals for cardiac arrhythmias. In addition, blood vessels constrict and elevate blood pressure. Both effects increase the workload of the heart, which can lead to heart failure. --David Iberri (talk) 19:21, 18 March 2007 (UTC)

narcotics

Is fentanyl the strongest??? Where can I find a chart of the strengths of the different kids of narcotics??

Lifestyle Change With Dramatic Results in One Year

Hello. A few years ago I remember reading an article in Reader's Digest about a middle-aged, potbellied balding lifelong smoker who decided to change his lifestyle and observe and document the results after exactly one year.

He even had before-and-after pictures: the "before" picture shows an overweight, flabby, pasty-complexioned, balding man in his mid-forties with glasses and a decent-sized paunch smiling sardonically, sitting down on a chair wearing red short-sleeved tights flexing his right biceps. The picture looked as ludicrous as it sounds. The accompanying article detailed his lifestyle: sedentary job, no exercise for God knows how long, smoker since age fifteen, 5'10" tall weighing 197 lbs., with a penchant for fast foods preferably in the super-size range.

The "after" photo showed the same man, this time in Speedo swim trunks, and by golly you wouldn't believe that this was the man who seemed destined to die of either a heart attack, stroke, cancer or some other such cause. He was standing and flexing the same right biceps, only this time there was a dumbbell gripped in his right hand and he was in the middle of doing a curl. His whole physique was nicely sculpted (not by Mr. Universe muscle-bound standards), from the top of his (still-balding) head, down to his taut and sinewy calves. Gone were the jowls on his bespectacled face; he was still smiling, but this time with more than a hint of pride showing on his glowing, finely-chiseled face. His complexion was now ruddy, and his jawline and cheekbones were well-defined.

Unfortunately, the article just gave a cursory description of his lifestyle change: stopped smoking, started eating right and exercising, both aerobically and with weight/resistance training. The point this article was trying to make was how dramatic, in just a year's time, the human body can change for the better if a lifestyle change is made and adhered to.

My question: does anyone out there have the details (well, more of them than was mentioned in that short Reader's Digest article) of how this guy did it, along with how he stayed motivated, how he overcame the many hurdles he surely must have encountered (including, without doubt, the pain of realizing the existence of muscles he never knew he had), what kind of exercises he started with, how he pushed himself to exercise progressively more without hurting or damaging anything, what kind of diet he followed, etc.....and most importantly, IF he was able to sustain this lifestyle change after that one year of keeping his nose to the grindstone so that it was a permanent change...or if the satisfaction of knowing that he could do it (that he in fact did it) proved enough of a reward for him to go back to his old, unhealthy comfortable ways?

My interest in this is more than academic; I will be turning fifty-one this year, and I have a lot in common with the "before" man right now. I'm not THAT flabby yet, but I'm getting there. My recent move to California from New York two years ago did a lot more than anything else to make me gain considerable weight. I would like to find out everything I possibly could about what this man did and how he did it --- because believe me, if you didn't know that this was the same man, you'd swear that those photos - spaced only one year apart - were of two different people.

Thanks in advance for any information you may be able to provide.

Ron 66.125.195.85 10:41, 18 March 2007 (UTC)

I have never heard of the the example you mention Ron. I can however say that changing ones physique is more a question of mind than body. My advise for anyone who wants to change his lifestyle is too take it one step at a time and to use self forcing practices. What I mean with self forcing is to put yourself into a position where you can't back out of your plan. Make plans,put them on paper make them visible to yourself and others and set goals. And try to meet these goals. Having other people around you doing the same will also help a great deal(imagine trying to stop smoking when the people around you aren't).

There are many websites (this one included) that can help you with practical advice on losing weight, gaining strength and increasing general fitness. I suggest you read those and ask around on fitness/weightlifting forums. You'll see that many people keep with their program because they like the results. They lose weight, get stronger, feel better. And on the oposite side when they don't keep to their self imposed program they feel bad, guilty even depressed. These positive and negative feedback systems are what keeps these people going.PvT 11:44, 18 March 2007 (UTC)

This may seem like an odd answer but I think geography has a lot to do with how long lifestyle changes take to come into effect. My opinion is that warmer climates will faciltate speedier recuperations. I have no citations and this edit may be swiftly reverted without explanation. Vranak

I think you might be right. In support of that hypothesis, people tend to weigh the most in winter, when it's coldest.[1] MrRedact 01:48, 21 March 2007 (UTC)

Have you tried contacting the people at Reader's Digest? As the name indicates, many of the articles in it (not the short bits like the joke pages or That's Outrageous! or whatever) are condensed versions of much longer print articles appearing elsewhere. You may be able to find the original article that way. This reference to the original article will appear in the print edition, so if you can dig up the actual old RD, you can get it that way, too. This might be a job for your friendly local dead-tree reference desk. --ByeByeBaby 07:37, 19 March 2007 (UTC)

Superconducting Super Collider

What happened to the partially dug part of the Superconducting Super Collider after the projects cancellation. Seeing as the tunnel system alone is potentially valuable for future large synchrotron projects surely? Or is there no benefit to a more powerful synchrotron than LHC? Philc _T^E_C^I 16:08, 18 March 2007 (UTC)

In short, politics plays a larger role than practical reasoning when it comes to multi-billion dollar science initiatives. The SSC is probably dead forever, and very probably due to a petty rift between the funding source and the potential users. Nimur 19:07, 18 March 2007 (UTC)

I live in Cedar Hill, Texas just a few miles from the site of the SSC. Part of the tunnel still exists - but they never did finish digging it - so it isn't a 360 ring - I think about a quarter of it was finished. That makes it pretty unsuitable for use for other synchrotron type applications. They used to run tours of the abandoned site - and they keep trying to come up with uses for the place - I think for a while it was used as a mushroom farm. But I very much doubt that any particle physics will ever be done there. SteveBaker 20:18, 18 March 2007 (UTC)

formula for an electric fan cooling a closed room

Is there a formula for figuring out how long it would take an electric fan to cool a closed room at a specific temperature. I have a temperature, the size of the room, the radius of the blades and the revolutions per minute. I'm trying to figure out how long a room can be cooled in the first hour it runs. If there is a formula, could you please advise?Thank you71.224.93.101 18:30, 18 March 2007 (UTC)

A fan wouldn't cool a closed room, it'd heat it up. -Wooty Woot? contribs 18:37, 18 March 2007 (UTC)

You might check out the heat equation, but it is of limited use since convection is the predominant mode of heat transfer in a room. You will need to make several questionably valid assumptions about laminar flow and an ideal source of cold air (i.e. fan in front of the refrigerator, or a cool outside window). Then you can apply those boundary conditions to this differential equation:

${\partial u \over \partial t}=k\left({\partial ^{2}u \over \partial x^{2}}+{\partial ^{2}u \over \partial y^{2}}+{\partial ^{2}u \over \partial z^{2}}\right)=k(u_{xx}+u_{yy}+u_{zz})\quad$

In practice, you will need something like a Finite Element Analysis simulator or some other computer package to solve this for a non-uniform shaped room.

A much much simpler equation is Newton's law of cooling. To apply this to a fan, you must again assume that the fan is blowing cold air from somewhere else (such as outside the room). However, it will conveniently give you a time-constant $\tau$ which is the closest way to answer your question. Nimur 19:12, 18 March 2007 (UTC)

In retrospect, I think these equations (and articles) might have scared you off more than helped you. Here is the first thing you need to know: fans do not cool anything, they only move air. If they are moving cool air into a hot room, that can have a cooling effect. (Thus the fan must be placed in front of a window or ice-box!) The rate of cooling depends on the temperature difference between the hot room and the cool air, as well as the amount of each.

You will have a tough time measuring how much air the fan moves, so you should make a first-approximation that it is moving air in a straight line. I can't think of a simple way to measure its speed. You might try some geometric calculations based on the pitch of the blade, the cross-sectional area of the fan, and the speed of rotation (try to imagine that you're conserving the volume of air). This will be messy and approximate, since no physical law requires conservation of volume in flowing air! Alternatively, you can look up linear flow rates from a catalog.

Once you have the amount of cool air in the room at any one time, you can apply Newton's cooling equation as linked above. Assume that the cold-source is the "constant" amount of cool air (though the actual particles are constantly moving). Solve for the time constant.

Alternatively, you could assume displacement of the room air, in a proportion of (fan flow rate)/(total room volume) per second. Calculate how long it would take to displace 99% of the room air (or any other arbitrary "final" cooled amount). Hope this helps,

Nimur 19:23, 18 March 2007 (UTC)

A fan running in a closed room would not cool the room. It would heat the room up an equal amount as an electric space heater drawing the same wattage. This sounds like someone gave you a trick question. Edison 04:46, 19 March 2007 (UTC)

Yes, as it has been repeatedly stated, the fan cannot cool anything. It can only move cool air in if there is an external source of cool air (open window, or an air-conditioning unit / ventilation system). Nimur 09:05, 19 March 2007 (UTC)

There is actually one way a fan can cool a closed room, via evaporative cooling. That is, if you aim a fan at a puddle in the room, this will cause the puddle to evaporate much more quickly than it otherwise would. And, as the water evaporates, the room cools (although the now more humid room may not feel cooler). The reason a fan blowing on you feels cool is the evaporative cooling of sweat it causes, as well as blowing cooler, dry air from the room on you and blowing the hot, humid air around your body away. StuRat 16:41, 19 March 2007 (UTC)

There is evaporative cooling, but can you prove that the cooling in a closed system is greater than the heating from the power dissipated by the fan? I once saw someone try to cool a machine in a closed room by aiming four 5 hirsepower fans at it, and the kilowatts of power dissipated by the fans made the heating worse. Can you prove that adding water to the system would have cooled the room, if it were a closed system? What happens when the air is saturated and the fans keep running? Edison 14:07, 20 March 2007 (UTC)

Trend and Pattern

I am analysing some biological data, and am having to comment on the trend and pattern in the data. I was wondering what exactly is the difference between a trend in data and pattern??? 89.241.4.129 19:32, 18 March 2007 (UTC)

I would say it is a matter of word choice. Perhaps trend is specifically within one graph (i.e. "data is a diagonal line with slope M", while pattern refers to the same trend across many different graphs of similar experiments?

Wiktionary says:

• Trend - Inclination in a particular direction; tendency; general direction; as, the trend of a coast.
• Pattern - arrangement of objects, facts etc. which has a mathematical, geometric, statistical etc. relationship

Nimur 19:52, 18 March 2007 (UTC)

Pig Gametes

Hi there, I'm having a spot of trouble finding what I need. I'm looking for what male and female gametes in pigs are called and I seriously can't find it. If you could help that, would be great.

Much appreciated. —The preceding unsigned comment was added by 71.229.138.46 (talk) 21:03, 18 March 2007 (UTC).

In most animals, the male gametes are spermatazoa (sperm) and the female gametes are oocytes (eggs). I don't know if there's a special name for pig gametes... My recent pig research has led me to the Pig Factsheet from the Pork Information Gateway (P.I.G.). Hope this helps, Nimur 01:00, 19 March 2007 (UTC)

LEP vs Tevatron

The LEP article states that "To date, LEP is the most powerful accelerator of elementary particles ever built." Now, I also know that LEP could only accelerate particles to 45GeV, and the most energetic collison it produced onl just topped 104 GeV. Whereas the Tevatron could accelerate particles to 1TeV, and produces collisions of up to 1.96TeV. Are these statments inconsistent, or is there some subtle distance between the energies of particles and the power of the accelerator, or is someone being perdantic with the definiton of elementary particles, seeing as tevatron accelerates protons and antiprotons, which's position as elementary particles is subject to debate seeing as they are constructed of smaller particles, however, they cannot be broken down. Philc _T^E_C^I 21:13, 18 March 2007 (UTC)

Actually, although you can't see free quarks, protons can be 'broken down' and form new hadrons. It is the quarks and gluons inside the protons which actually interact, so the centre of mass energy of the proton-antiproton collision (1.96Tev) is not the energy of the reaction, which is less. However as there are three valence quarks, a third gives an approximate guide to the magnitude of the energy of the quarks, which would still be higher than at LEP. The statement definitely refers to protons not being elementary, but is possibly misleading as elementary particles within the proton are accelerated along with the proton.Jameskeates 13:32, 19 March 2007 (UTC)

So is the statement true or not,should it be changed to most powerful lepton accelerator as opposed to elementary particle accelerator. Philc _T^E_C^I 14:57, 19 March 2007 (UTC)

I beleive the statement is true, the proton is not an elementary particle. Whether it's useful to have it in the article or not, I don't know. But that's for the article's talk page.Jameskeates 15:36, 19 March 2007 (UTC)

I think it should just be taken out, it's misleading. [Mαc Δαvιs] (How's my driving?) ❖ 16:16, 19 March 2007 (UTC)

High blood pressure - can it be alleviated by controlled blood-letting?

My grandma (who suffers from high BP) asked me this today (no, she's not thinking of trying it - it was just a hypothetical question). If a person's blood pressure is too high, would it be possible to return it to and keep it within acceptable limits by occasional, precise bloodletting? If not, why not? This has got me curious now... --Kurt Shaped Box 21:50, 18 March 2007 (UTC)

• I don't think it is. If the pressure is too high because the blood is pumped 'too hard', the pressure will return when new blood cells have been formed. If the pressure is high because of clothed arteries, only operation on the arteries is going to alleviate it. And if the blood letting is not as precise as you hoped, the pressure will fall far below an acceptable limit. I'm therefore doubtful it would have a positive effect. - Mgm|^(talk) 22:42, 18 March 2007 (UTC)

(edit conflict)

No. I felt very strongly that blood pressure would go down, so I did a study at the red cross office in our hospital. Every nurse there agreed with me - BP would go down. To everyone's surprise, blood pressure goes up after giving 1 pint of blood. In some people, it goes up a lot. --Kainaw ^(talk) 22:44, 18 March 2007 (UTC)

That's the baroreceptor reflex at work. Decreasing blood volume (as occurs during phlebotomy) does transiently lower blood pressure, but the baroreceptor reflex acts so swiftly that blood pressure is rapidly brought back to its initial value. In individuals with normal blood pressure, the baroreceptor reflex would bring the blood pressure back to normal (120/80 mmHg). But in individuals with chronic hypertension, the set point of the baroreceptor reflex is elevated, so that a drop in blood pressure will be rapidly brought back to the initial hypertensive values. There's no way, save a defective baroreceptor reflex, that controlled bloodletting (ie, not a massive hemorrhage) will acutely lower blood pressure. However, I'd bet that a prolonged course of bloodletting, in which individuals are repeatedly drained, will transiently depress blood pressure so frequently that the set point of the baroreceptor reflex will be decreased, causing blood pressure to drop. I'm sure this has been tested in dogs somewhere, anyone care to check PubMed? Cheers, David Iberri (talk) 23:02, 18 March 2007 (UTC)

Maybe drinking more and thereby diluting their blood would help?

Dilution would be relatively rapidly corrected (via a decrease in vasopressin secretion), so that would be a pretty transient effect. Plus there's the danger of water intoxication by drinking so much water that you become dramatically hypoosmolal, which is a risk factor for neurological and other problems. --David Iberri (talk) 00:52, 20 March 2007 (UTC)

What about cutting yourself then drinking your own blood? would that help-- or would it just show that you have 'vampiristic' (is that a word?) tendencies? —The preceding unsigned comment was added by 88.109.124.137 (talk) 01:29, 20 March 2007 (UTC).

I believe the term for that is autovampirism. --Carnildo 23:38, 20 March 2007 (UTC)

Memory Retrieval Technology

What exactly is the status of being able to retrieve memories from one's head via technology, and save them as, say, a .avi file on my computer (ala Minority Report)? I can't imagine it's very far... Here7ic 22:45, 18 March 2007 (UTC)

Considering we still don't know how the brain really works, we're still pretty far. And I doubt my mind would resort to a Microsoft container format. --Wirbelwindヴィルヴェルヴィント (talk) 22:51, 18 March 2007 (UTC)

Perhaps AVC would be better for you?? Here7ic 23:21, 18 March 2007 (UTC)

Not enough is known about the storage mechanism to perform any real raw extraction. I'm inclined to believe that human memories are stored in wiki format, with vast amounts of metadata embedded into every element. Nimur 01:09, 19 March 2007 (UTC)

Point well stated. Here7ic 00:23, 21 March 2007 (UTC)

March 2007 issue of SA had a good article that is also available in its entirety online for free. Someday we will have digital memories. Today for some. -- atropos235 ✄ (blah blah, my past) 05:44, 19 March 2007 (UTC)

Blood test

When did it become possible to determine the gender of the unknown donor of a blood sample (by US scientists)? I want to know if it was possible in 1955 and/or 1966. - Mgm|^(talk) 22:54, 18 March 2007 (UTC)

I didn't know it was possible now. Is it possible to detect trace amounts of sex hormone or is there some other technique? I have never heard of this ability. Nimur 01:14, 19 March 2007 (UTC)

We can do DNA tests on a sample NOW; you only need to look for X and Y chromosomes. - Mgm|^(talk) 11:24, 19 March 2007 (UTC)

It has been possible since the discovery of the significance of the Barr body (present in females only) in 1949. This would show up best in WBCs when stained with methylene blue, but can also sometimes be apparent in the usual CBC stain, Wright's stain. - Nunh-huh 01:35, 19 March 2007 (UTC)

Note, most sex hormones are found in both males and females anyway. The difference is in the level. Nil Einne 09:40, 21 March 2007 (UTC)

• Thanks. - Mgm|^(talk) 11:24, 19 March 2007 (UTC)

Alum

What is alum and hhow does it grow crystals????????????????? -Olivia Cole,10,IL

Did you read the Alum article? The section you are interested is most likely the Potassium Alum section. Alum is a double salt, made from Potassium, Aluminium, sulphate ions and water. It occurs naturally as a mineral. It has been known since ancient times. It is ised in dyeing. Aluminium is named after Alum. There is one Potassium atom for every Aluminium atom. The chemical formula is KAl(SO₄)₂(H₂O)₁₂. Alum dissolves more in hot water than cold, so if you dissolve as much as you can in hot water, and then let it cool there will be too much alum in the water. If you add a tiny alum crystal to the supersaturated solution, the crystal will grow rapidly. When the alum is insolution the sulphate, aluminium and potassium ions are wandering all over the place in the water. However when they turn into a crystal they are neatly arranged in a particular pattern. GB 23:33, 18 March 2007 (UTC)

March 19

CO2 recovery and reuse

How difficult would it be to create a mechanical or chemical process to take CO2 out of the exhaled breath and reuse it to make soda water? —The preceding unsigned comment was added by 71.100.1.200 (talk) 02:35, 19 March 2007 (UTC).

Bubbling CO2 through solutions will cause it to dissolve, this can be observed by exhaling through a straw into a solution of bromothymol blue in a neutral solution of water. (do not do this without the aid of someone experienced in chemistry) This process isn't very complete though, rebreathers rely on a scrubber to remove the CO2 from the breathing gas, typically soda lime. Once it's bound chemically, there is probably some path that would convert it into relatively pure HCO3 sol'n, but it would cost way more than creating soda water the ol' fashioned way. -- atropos235 ✄ (blah blah, my past) 04:39, 19 March 2007 (UTC)

Sub-Lightspeed Craft

If a spacecraft where built and had the capabilities to travel at half the speed of light how much shieling would it need? For example in the Project Daedalus article there is a link that describes how Daedalus would need an erosion shield for travelling at twelve to sixteen percent the speed of light, they go further to say it would probably be made out of Berillium. So to restate the question how thick would a berillium shield have to be for a craft traveling at 50 percent the speed of Light? —The preceding unsigned comment was added by 68.120.225.214 (talk) 04:18, 19 March 2007 (UTC).68.120.225.214 04:19, 19 March 2007 (UTC)

Simply put, Project Daedalus is a fictitious foray by a non-technical group of space enthusiasts. The engineering and scientific claims are not necessarily realistic. To give a straightforward answer like "30 cm of beryllium shield" would be silly - it would assume that somebody has gone through the difficult engineering and design process for a non-existent spacecraft, making the necessary tradeoffs and compensating for a minimum level of safety. In a practical sense, it is impossible to make engineering assessments about technologies which are so distant from the present state of the art. (Present craft do not travel at even a remote fraction of that speed, so there is no way we could compare our designs against it in a meaningful way). Nobody can possibly forsee the actual required specs for a craft which is many many generations beyond present-day space vehicles. In the mean-time, you might look at the Atmospheric reentry to learn about real shielding on actual spacecraft. On a more philosophical note, some of these scientific studies, such as SETI, are not meant to actually yield conclusive answers about anything, but are more of a way to stretch our way of thinking. They shouldn't be taken at face value - in fact, any level of scientific analysis that goes into them makes it blisteringly self-evident that such projects are impossible (in the foreseeable future). Nimur 08:53, 19 March 2007 (UTC)

Granting Nimur's comments as true for actually building such a craft, it can still be fun and informative to do back-of-the-envelope calculations for this kind of thing. For example, you could take the density of matter in the interstellar medium, and calculate the explosive power of each of those atoms hitting your craft at at 1/2 c and see how far you can get with a given shield. --TotoBaggins 13:12, 19 March 2007 (UTC)

My idea is to clamp onto an metallic asteroid or even a small moon, and keep that in front of the spacecraft both as a shield and a source of material for a linear accelerator (which would eject particles at the speed of light for propulsion). It might not be as effective per meter as beryllium, but you would have many kilometers of this material between the occupants and particles. StuRat 15:52, 19 March 2007 (UTC)

in the Discovery channel they had a episode (cant remember the name of the show) in which they show a forcefeild generator. yes its a real one however the only problem with it is that it takes a machine the size of a bedroom to generate the energy to protect a can of soda. its acctually more like a plasma shield and had a blueish green look to it it was pretty awsome. Maverick423 17:05, 19 March 2007 (UTC)

Thank You all for the answers you have given me but I think it is sad to say that Daedalus is out of our time reach. I look at the rapid progress of technology and doubt almost nothing as far as how far technology can progress.67.127.164.153 03:04, 20 March 2007 (UTC)

direction of rotation for IC engine

What is the convention for the direction of rotation for an internal combustion engine?

And is it only the direction of rotation of the starting (electric starter motor, pull start or other) that determines this?

Thanks 139.163.138.10 04:53, 19 March 2007 (UTC)

You can't spin an ICE in a different direction than it was designed for, the cams will not open and close the valves at the correct time, nor will any of the devices (alternator, coolant pump, oil pump) connected to the engine with the fan belt work correctly when spun backwards. I'm not sure if there's a convention to the direction, but my Corolla's engine spins counter-clockwise when viewing it from the flywheel side of the engine. -- atropos235 ✄ (blah blah, my past) 05:40, 19 March 2007 (UTC)

Given that there are IC engines that will run backwards perfectly well then I think you might need to qualify your answer. Almost all would rotate backwards, they just wouldn't run. In a 4 stroke the valve events would be all wrong, you'd be unlikely to get it to run backwards, unless it had special timing gear and a special oil pump.

For car engines most run anticlockwise from the flyweel end, but historically many manufacturers have ignored it, including Honda for many years. Greglocock 06:46, 19 March 2007 (UTC)

Right, there's nothing fundamental about internal combustion engines (encompassing a very broad range of machine designs) that prevents them from rotating or even operating in either direction (nor anything that requires them to have a rotating shaft, for that matter). Many specific rotating-shaft ICE designs are built to only run in one direction, but I've seen (older) diesels that will actually run in reverse, though poorly. Sometimes the reason that the engine only runs in one direction is because it is optimized for efficiency that way. Of course the reasons for choosing any ICE design feature will vary depending on the application and the specific type of engine under consideration. -- mattb @ 2007-03-19T07:09Z

It seems to me that the sorts of IC engines used in model airplanes (those engines having no valves) would probably be perfectly happy to run backwards, although they wouldn't be of much use while operating in that mode. And, BTW, with the exception that its cooling fan probably would be less efficient, the alternator on a modern car engine would work perfectly fine running backwards.

Atlant 12:50, 19 March 2007 (UTC)

More PSU Shocks

I recently reported that I received an electric shock while simultaneously touching my PSU and a radiator, even though the PC was off. Today, I touched a PSU from a completely different (and two week old) computer and another radiator in the same house, and while the PSU was unplugged from the mains no less, I received a similar shock (although slighltly lesser in intensity), to that which I received a few weeks ago. What is going on? --Seans Potato Business 06:05, 19 March 2007 (UTC)

I would guess that it was you that shocked the computer in this case, not vice versa. -- mattb @ 2007-03-19T06:08Z

Maybe it's a recurring phenomenon with you because of some behavior or environmental circumstance. What sort of shoes are you wearing when working on computers? Do you drag your feet on carpeted floors (this can build a lot of charge!) Do you properly ground yourself to the chassis (at least by discharging yourself to the case, or if you really want to be a nerd, you can actually use a ground bracelet). This might prevent shocks in the future, it seems like you are particularly susceptible. Nimur 09:00, 19 March 2007 (UTC)

Putting aside the issue of shocks from static electricity, you need to know that PSUs have substantial electrical filters to prevent the egress and ingress of radio frequency interference (RFI) from/to the computer. These filters connect substantial capacitors from the chassis of the computer (and the "ground"/"earthed" terminal of the line cord) to both the hot/live power line wire and the neutral/return power line wires. The end result is that if you don't properly ground/earth the computer, the case will be floating at about 1/2 the line voltage and yes, you'll get shocked every time you connect yourself between the computer's case and something that is earther (such as your radiator). You may also get shocks from the monitor or any other part connected to the computer's case.

Properly ground/earth your computer.

Atlant 12:55, 19 March 2007 (UTC)

Can I improvise an earth by connecting the case to the radiator with a peice of wire/jumper cable? I dont want to go through the rigmarole of trying (and failing) to get the house properly wired since it's apparently not a legal requirement where I'm living. It's apparently not uncommon in the Netherlands. I rent one room and will be out of there in a few months tops, to go to university. Thanks for the advice so far. :) Seans Potato Business 16:12, 19 March 2007 (UTC)

It's probably a bad idea to have exposed wiring (grounded or otherwise) randomly attached between your computer and the radiator. I think the safest course is to have a professional electrician (or your landlord) take a look at the problem. Barring that, you should probably close up your computer case entirely and try not to touch it. You might have a serious issue at hand, you should avoid adding stray wires. Nimur 18:54, 19 March 2007 (UTC)

The rewiring suggestion is not applicable to my situation. I don't wish to go into why. It's surely a better idea to have an exposed earth connection than none at all. Seans Potato Business 21:30, 19 March 2007 (UTC)

Do not ever test for electricity by seeing when you get a shock, since electrocution is possible. Hardware stores and Radio Shack sell inexpensive digital voltmeters. The radiator would normally be grounded (earthed) through the cold water pipe to this planet most of us inhabit. But that is not guaranteed. There can be insulating fittings in pipe connections, and water meters insulate the building pipes from the water main ground unless an electrician has properly made a substantial and solid ground jumper around the water meter. Electric water heaters often leak AC to the water pipes and water supply. I saw a case where a bathtub was electrically energized by a thermostat wire which was exposed and touching a drain pipe. So it is possible that the couputer is somehow grounded, through a modem or phone line or broadband cable ground, and the current is going from an energized radiator to the ground on the computer chassis. Or as you assume the computer could be what is energized, through the power system or from an energized signal wire ground. Have someone knowledgable about electricity test with a voltmeter. A piece of metal pipe going into the ground is a pretty good reference groung for testing purposes. I have learned to doubt the solidness of various supposed grounds you find inside a structure, since there are an infinite number of ways for homeowners and hacks to miswire things. Running a "ground wire" from a computer to a radiator is not recommended, since you have no solid assurance that the radiator is actually grounded. Edison 14:22, 20 March 2007 (UTC)

If I use my voltmeter to compare the red wire from my PSU with the radiator, and it reads 5v, then must the radiator be earthed? --Seans Potato Business 01:29, 21 March 2007 (UTC)

Perhaps, but the trouble is that it's very hard to evaluate the "quality" of the earth that the radiator is providing. A good earth connection (ground) today might turn into a poor connection as things corrode or the plumbing is modified. Another concern is that if you flow any substantial electrical current (even the leakage current from your computer's PSU) into the radiator, over time, galvanic corrosion can occur elsewhere in your plumbing. It's less of a problem with ordinary AC mains current than with DC, but it's still bad practice. Edison gave the best advice: provide a real earth ground connected to a grounding rod. Failing that, you might be able to obtain an "isolation transformer" or isolating UPS and operate your computer from that.

Atlant 12:40, 21 March 2007 (UTC)

molecular vibrations

I may be the expert you are looking for (Author "Vibrating Molecules, 1971) This is a very large field, so I will welcome any guidance that can be offered. Peter Gans e-mail as userer name at hyperquad dot co dot uk Retired lecturer, Leeds University, UK petergansPetergans 07:59, 19 March 2007 (UTC)

Welcome! I see you've created an account already. If you'd like to contribute, you can edit any page by clicking the "EDIT" tab at the top. You might want to look at Molecular vibration to start. Feel free to hang around the Reference Desk as well. I've added a standard greeting at your user talk page so you can find some quick links to introductory material (how to contribute, how to edit, etc). Nimur 09:10, 19 March 2007 (UTC)

reticular fibers

is it possible for reticular fibers to have parenchymal function?

According to the article on reticular fibers, "Networks of these fibers make up [... the] parenchyma of liver, testis and lung." I'm not a med student, so I don't have a good grasp on what that means. -- atropos235 ✄ (blah blah, my past) 16:26, 19 March 2007 (UTC)

yeah i saw that but have doubts since i haven't read anything like that elsewhere...

Quick comment, if you don't want your IP address shown (as you keep removing the automatic {unsigned} tag from each post you write), you can create an account which will hide it. -- atropos235 ✄ (blah blah, my past) 21:58, 19 March 2007 (UTC)

Liquid conversion

Many drinks on the internet are posted in CL and I was wondering what that is converted into on 1 OZ ? It certainly cannot be 1-1 can it or maybe it is? —The preceding unsigned comment was added by 70.50.185.202 (talk) 16:06, 19 March 2007 (UTC).

"CL" could mean centiliter, though it would properly appear as "cL" or "cl". According to Google:

one centiliter = 0.338140226 US fluid ounces

one US fluid ounce = 2.95735297 centiliters

-- atropos235 ✄ (blah blah, my past) 16:15, 19 March 2007 (UTC)

Yes, they mean centiliter. Conveniently, one cL is almost exactly 1/3 fl. oz.; there are three centiliters to the fluid ounce. TenOfAllTrades(talk) 16:21, 19 March 2007 (UTC)

Or of course if you mean Imperial fluid ounces (which are a bit smaller than US), it's 0.35195008 fl.oz. --Anon, March 20, 2007, 22:15 (Imperial), um, (UTC).

Ear bleeding

(NOTE: This is a medical question, but I am not asking for medical advice; merely curiosity.) A number of the more fantastic TV shows and films I've seen show bleeding ears (from the canal, not the lobe) as part of particularly gruesome death scenes. However, I've never actually heard of it being a symptom of any disease, and my fairly in depth first-aid book carries no mention of bleeding ears, while the only mention on Wikipedia is ear bleeding caused by over vigourous ear-wax removal. So, are there any diseases or accidents, other than direct damage to the ear itself, which would cause this? Laïka 16:59, 19 March 2007 (UTC)

I'm guessing some kind of trauma to the brain or a burst eardrum might cause ear-bleeding. Otherwise TV shows would be a bit strange. "What happened to him, doc?" "Vigourous ear-wax removal, the silent killer." "Dear God!" -GhostPirate 17:09, 19 March 2007 (UTC)

When I had an infected tooth I bled from my ear. Anchoress 17:23, 19 March 2007 (UTC)

Wonderful soundbite! ---Sluzzelin talk 17:26, 19 March 2007 (UTC)

Thanks. My cat's breath smells like cat food. Anchoress 21:26, 19 March 2007 (UTC)

• Our article on Bleeding states "Externalised bleeding from the ear may indicate brain trauma if there has been a serious head injury...". Bleeding from the ear is also mentioned in Cholesteatoma. Johntex\^talk 20:00, 19 March 2007 (UTC)

In most TV shows, bleeding from the ear is meant to represent a posterior basal skull fracture. Leaking CSF from the ear would represent an anterior basal skull fracture, but doesn't look as dramatic.... - Nunh-huh 03:35, 20 March 2007 (UTC)

Ok, thanks for that! Laïka 08:13, 20 March 2007 (UTC)

I suspect (without evidence) that the movie makers like it because it's easier to trickle some fake blood out of someone's ear/nose/mouth and produce the impression of serious injury than it is to have their makeup people produce a really convincing external wound and tie the actor up in makeup for hours while they apply it. SteveBaker 14:38, 20 March 2007 (UTC)

Treadmills

While in the gym yesterday, I spent a half hour on a treadmill and it very apparent that the effort (which equates, I guess, to "work done" or calories burned) running X miles on a treadmill appears to be much less than for an equal distance running on a pavement. Discounting variation in terrain on road running, what I would like to know is, what is the major contributing reason for comparative ease of running on a treadmill? I can think of four significant possibilities:

• Enforced pace maintenance when running on the treadmill
• Cushioned running surface on the treadmill
• Lack of wind resistance when running on the treadmill
• Lack of leg energy used to "push forward" on the treadmill

I would guess that these are listed in order of least to most influential, but would welcome any pointers to expert analysis, particulary regarding the actual difference in leg energy expended in running on the spot compared with running forwards. Finally, is there any data available on the total amount of calories I would burn per mile of treadmill running v road running. Thanks. Rockpocket 19:16, 19 March 2007 (UTC)

Those are good possibilities, and if you were holding the handlebars of the treadmill, I will also propose reduced arm movement on the treadmill. − Twas Now ( talk • contribs • e-mail ) 19:36, 19 March 2007 (UTC)

• I would suggest that outside, no ground is perfectly level. You are going up and down hills or at least slight gradients. Not true on a treadmill. —The preceding unsigned comment was added by 74.134.146.52 (talk) 19:54, 19 March 2007 (UTC).

Scientifically, the main reason may be the treadmill base acting as a linear spring. There has been tons of studies looking at how to make springy running shoes, but they all flopped... --Zeizmic 20:13, 19 March 2007 (UTC)

• Pure speculation on my part, but I wonder if some treadmill manufacturers deliberately miscalibrate the system to make you feel happier about how much work you have done? Johntex\^talk 20:15, 19 March 2007 (UTC)
• I think Zeizmic's explanation is the correct one. The baseboard of a treadmill (the surface underneath the moving belt) is generally a rather springy plywood board. This gives a lower-shock impact (which is easier on the tendons of the ankle and knee) and gives a bit of energy return. That lower impact is the design goal - it cuts injuries, and makes the treadmill suitable for those recovering from injury (it's common for athletes who are recovering from injury to be told to walk or run on a treadmill, but forbidden from running on an asphalt or concrete surface). The energy return (the bounce-back from that springy surface) is a side effect of that, and indeed it will lessen the effort of a given run (although by how much I'm not sure). A very similar effect (with the same underlying design-goal) will be experienced when running on a nice rubber-crumb running-track. Darryl Revok 11:22, 20 March 2007 (UTC)

Incidentally, the energy usage of a treadmill can be increased by using an inclined treadmill, or by just increasing the pace. StuRat 13:09, 20 March 2007 (UTC)

forget the treadmill grab a bike. i lost 50 pounds in one month by bike riding every day for about 5 hours (not all at once) and i still ate like a pig =) but maybe the mountains had something to do with that. so if thats the case just make your treadmill incline to its highest point and trust me you will get a pretty good work out. Maverick423 15:19, 20 March 2007 (UTC)

Speaker wiring question

This weekend I helped my friend set up a home theatre system. The reciever is a Yamaha RX-V2500 like this one. We hooked up seven Definitive Technology speakers for the main room, no problem. On the "B speaker" connections, we rigged up a pair of Infinity outrigger speakers like these out in the back-yard. They also work fine, except that they don't provide enough coverage for the whole back-yard. We would like to add a second pair of speakers to the back-yard.

The question is, can we hook up a second set of these outdoor speakers in series to the first set? Thanks for your help. Johntex\^talk 19:55, 19 March 2007 (UTC)

If you meant in parallel, then yes, you can. However, the same power will be distributed over the speakers so each one might not be as loud. --Wirbelwindヴィルヴェルヴィント (talk) 22:54, 19 March 2007 (UTC)

Thanks for your reply. I actually did mean in series. Because of the way the wiring runs, it would be convenient to run the wire from the receiver to the first set of speakers (as they are wired currently) and then to take wire from each of the first speakers to the second pair. Would that work?

Part of the problem is just that the Infinity speakers are quieter than the Definitive Technology speakers. What my friend wants to do is to have both A + B on a once, so that the same music can be playing in the house and outside on the patio. However, the receiver does not have a seperate volume for A vs B. A volume that is good for the B speakers is deafeningly loud for the A speakers. We thought about putting a seperate volume control onto the B speakers, and we shopped for one. However, all the ones we saw at our Radio Shack would not accomodate the size wire we are using. I don't remember the gauge, but the wire itself is pretty thick and it is well protected for outdoor use. Having already purchased and run the thick wire, we are reluctant to replace it with cheaper, thinner wire that would fit into one of these volume control boxes.

So, is it possible to connect speakers in series, or is there a better solution? Johntex\^talk 23:04, 19 March 2007 (UTC)

Please check the specifications in the manual for the amp, and see if the series impedance (the sum of the individual impedances) is within the allowance for the amp. The amp is more of a concern than the speakers or the wire. Edison 04:45, 20 March 2007 (UTC)

First up, putting a second set of speakers in series is /safer/ than in parallel, so far as your amp goes. BUT you will make the original set quieter, in fact there is a very good chance that you'll end up with less noise outside than before. I wouldn't recommend putting speakers in parallel unless you understand the specs very well, or your amp has good output circuit protection. I wouldn't risk it. Really the best thing is to go and find another amp, then T the input to the first amp into the second amp, or take the line out signal from the first amp into the second one. Greglocock 07:36, 20 March 2007 (UTC)

Affordable solar panels

I'm an eco-conscious individual who rents his appartment (in Boston, MA) and whose wallet isn't too fat. I'm thinking of sticking a small solar panel on my roof to generate electricity, probably to sell it back to the grid. Is this feasable nowadays? And how much initial investment would such a thing (both the panel and hooking up to the grid, however you do that) cost?

Thanks,
Mike, 19:58, 19 March 2007 (UTC)

• It is feasible, but how feasible it is depends on many things. Climate is one, government rebates are another. The time to pay-back an investment in solar energy is typically 4-10 years, depending primarily on these fators. Our article on Solar power has a lot of info. Johntex\^talk 20:03, 19 March 2007 (UTC)

• And also see Deployment of solar power to energy grids. Johntex\^talk 20:06, 19 March 2007 (UTC)

If you're in Boston, you're probably getting energy from NSTAR, and as far as I can tell, they don't really do green energy :/ - that is, I don't think they don't have any programs to encourage or enable environmentally minded people like yourself to take initiative. Good luck though - I know you can connect solar systems into your house mains, but I wouldn't expect to get paid for it - could be wrong though. --18.214.0.135 04:14, 20 March 2007 (UTC)

Buying power back may be automatic. That is, the present meter might run backwards when you provide power. I'd aim to meet, but not exceed, the total power needs of the tenant. This means you would produce excess power on sunny days but not enough on cloudy days and at night. On the other hand, even if they don't buy back the excess, you can still provide it to your tenants as a plus ("reduced electricity bills during the day, due to solar cells on the roof") and possibly charge higher rent, as a result. This would be particularly valuable if you live in an area with insufficient power availability which has brown-outs or black-outs when all the air conditioners are on in summer. It does take quite a bit of power to run A/C, though, so you would need large solar panels. If not, at least they can run a fan when the A/C dies during a power outage. You might also want to consider passive solar heating. For example, conventional or vertical blinds, facing the Sun, which are white on one side and black on the other would allow the tenant to use the solar heating, but only when they want it. StuRat 13:03, 20 March 2007 (UTC)

Not particularly sure what the climate is like in Boston but if you use a fair amount of hot water, you may also want to consider a solar heated hot water system. Such systems tend to be more efficient then just generating electricity for obvious reasons. Of course, this would require plumbing and the like so may be too expensive for you Nil Einne 14:17, 20 March 2007 (UTC)

Electronics Express and walmart have the lowest prices on solar panels. walmart sells a panel that generates 12 volts for 9.99 and electronic express sells a 2X2 grid for 150.00 think that grid generates 240 volts. just rechecked *its been a while since i checked the site* no more 2x2 grids but they got a 18 volt panel for 16.00. however none of that wont do you any good if you got not light =P here is the link to the prices [2] and the link to the site[3] hope this helps you out with what your looking forMaverick423 15:24, 20 March 2007 (UTC)

Ok, thanks for the replies everyone! -Mike, 17:02, 20 March 2007 (UTC)

Mutation in nectariens

can someone explain how the mutation in the nectarines happens? why?—Preceding unsigned comment added by 83.135.36.133 (talk • contribs) 12:34, 2007 March 19

Well, the nectarine article says the fruit was grown in England as early as 1616, but that the history is "unclear". This source suggests they "probably originated in China over 2,000 years ago and were cultivated in ancient Persia, Greece and Rome." A few more details emerge here. -- MarcoTolo 23:10, 19 March 2007 (UTC)

The mutation is in the peach gene g (glabrous, "without hairs, smooth.") The mutation appears to be spontaneous, singular (i.e. just one mutation is all it takes), and is recessive (perhaps in Blake MA, "The JH Hale peach as a parent in peach crosses" Proc Am Soc Hortic Sci, 1933). -- MarcoTolo 23:23, 19 March 2007 (UTC)

earth and space science

fraction of difference between two fixed temperatures is called what?

${\cfrac {\Delta T}{T}}$ ? This sounds like carnot engine efficiency, but I might be misinterpreting your question fragment. Nimur 23:15, 19 March 2007 (UTC)

Or it could be just ${\Delta T}$, from ${\Delta T}={\cfrac {T_{1}}{T_{2}}}$ [Mαc Δαvιs] (How's my driving?) ❖ 05:45, 20 March 2007 (UTC)

$\Delta T$ would generally indicate a difference, not a fraction: $T_{2}-T_{1}$. -- mattb @ 2007-03-20T13:19Z

What is the complete breakdown for X55 Cr Mo V14?

I can find Cr (Chromium) and Mo (Molybdenum). These are used in selling knives as the materials the knife is made of.

Thanks,

Chris

V could be vanadium, which is used in some high-temperature stainless steels. From preliminary search, this means that the Chromium + Molybdenum + Vanadium total percentage is 14%. I can't find information on the X55. See our steel article or Stainless_steel#Types_of_stainless_steel... there's similar nomenclature in the latter article. It seems that steel standards are proprietary and expensive: this handbook costs >$500US! Nimur 23:08, 19 March 2007 (UTC)

out feet

Was wondering what may cause feet to be facing to the sides with respect to the movement of the person and what effects may this bring

—The preceding unsigned comment was added by Bastard Soap (talk • contribs) 21:39, 19 March 2007 (UTC).

No idea what causes it but my mum used to tell me off if she saw me walking at "ten to two". I happen to notice that the majority of people who walk like this have a rather 'lazy' looking posture, whereas I tend to walk a little more forest-gump like (???). ny156uk 21:56, 19 March 2007 (UTC)

Could be for stability. When I took fencing lessons, I was taught that my feet should be at 90 degrees to each other. Clarityfiend 22:35, 19 March 2007 (UTC)

This is called pronation of the feet, and may be due to flat feet. Here is a web article about it. If you are a runner, you should try to avoid this, as it has negative ergonomic effects and can adversely affect your speed. Nimur 22:55, 19 March 2007 (UTC)

(Insert standard medical disclaimer here). The illustration looks more like femoral retroversion to me. What effects this may have depends largely upon the age of the individual in question (i.e. its normal in infants, but may be somewhat concerning in adults). There is a good review of lower limb issues in children in the journal American Family Physician from August of 2003 (link). -- MarcoTolo 23:02, 19 March 2007 (UTC)

I heard an aunt describing a course to improve elderly people's balance in which they were told to walk like this for the improved stability. Aaadddaaammm 08:06, 20 March 2007 (UTC)

Also, I personally seem to have my feet attached to my legs in such a way that I either walk with my feet facing slightly outwards, or my knees facing slightly in. Seriously, if I extend my legs straight out with my knees facing up, my feet face out. Since, like Ny156uk, my mum told me off for walking with my feet facing outwards, I walk with my knees facing in. It hasn't seemed to lead to any problems, other than shoes wearing out in an uneven pattern, but I would advice anyone else in this situation to consult with an appropriate doctor to determine which manner of walking would be best before they settle into a pattern and their bones form to accomodate it! I assume this can't be too uncommon. <OT>I suppose I got a slight wiggle to my walk for my troubles, which is no bad thing, but I also got mocked by PE teachers for my running style.</OT> Skittle 17:22, 20 March 2007 (UTC)

Some martial arts and yoga often have you place your feet parallel rather than like the illustration. This always seemed unnatural to me. Any thoughts on this? —Pengo 13:28, 23 March 2007 (UTC)

science

What is the chemical symbol for sodium chloride and what is its compound's molecular weight?24.148.188.8 23:20, 19 March 2007 (UTC)

Did you look at our article on sodium chloride? --Wirbelwindヴィルヴェルヴィント (talk) 23:26, 19 March 2007 (UTC)

Focal point of an earthquake

What is the point on Earth's surface directly above the focus of an earthquake?

The epicenter. Did you check earthquake? Nimur 23:34, 19 March 2007 (UTC)

I'm not familiar with "focus," I learned it was "origin" or "hypocenter." [Mαc Δαvιs] (How's my driving?) ❖ 05:44, 20 March 2007 (UTC)

All three terms mean the same thing in this context. Note that this contrasts with the popular use of "epicenter" (of some other sort of phenomenon) to mean its origin or focus, and also with the use of "hypocenter" to mean the point on the Earth's surface directly below a nuclear explosion (otherwise called "ground zero"). --Anonymous, March 20, 2007, 22:19 (UTC).

March 20

Medical term needed

what is the equivalent Medical term for the tamil disease "Akki" — Preceding unsigned comment added by 122.164.132.63 (talk • contribs)

Herpes? [4] --David Iberri (talk) 01:52, 20 March 2007 (UTC)

(EC)This site claims that akki is Herpes simplex. -- MarcoTolo 01:54, 20 March 2007 (UTC)

Magnavox MWD2205 4 Head VCR/DVD Player Issues

I lost my manuel, and I am trying to find out if there is a tracking button on the player or the remote so that I can fix the tracking on a VHS tape. —The preceding unsigned comment was added by Andreagambler (talk • contribs) 03:28, 20 March 2007 (UTC).

• Owner's manual here; [5] --BenBurch 07:35, 20 March 2007 (UTC)

MONTREAL PROTOCOLS

By Who was the protocol developed ??

What are the major gudielines and how are they monitored ??

are there any consequences ?? —The preceding unsigned comment was added by 59.101.237.5 (talk) 10:07, 20 March 2007 (UTC).

Montreal Protocol. It is usually easier to check the article before posting here. —The preceding unsigned comment was added by 128.12.131.62 (talk) 10:27, 20 March 2007 (UTC).

Body colour changes due to diet

A while back I knew this person who had some sort of device with two metal prongs that they put in a glass of water. They claimed that it was silver and putting silver into the water. Also they claimed that if they drank too much they could turn grey. Sorry to be vage but thats all I have. Can anyone shed some light on this? I've heard they if humans drink too much carrot juce they'd turn orange but this really puzzeled me. Thanks! Think outside the box 12:19, 20 March 2007 (UTC)

That's not too vague. Both are true. Excess consumption of colloidal silver causes argyria. StuRat 12:40, 20 March 2007 (UTC)

Wow! I should warn them. Thanks for that StuRat Think outside the box 13:03, 20 March 2007 (UTC)

We have a sugar + colourings + additives + orange juice drink called Sunny Delight in the UK. It was really popular amongst kids about ten years ago. I remember reading in the paper about a kid who turned orange after drinking pretty much nothing else but Sunny Delight. As for the colloidal silver, take a look at Stan Jones - probably the most notable grey/blue skinned man in the world. --Kurt Shaped Box 13:06, 20 March 2007 (UTC)

Too much carrot or carrot juice can result in an orangey tinge to the skin. It appears to be something that may occur, especially when a infant switches to solids. Do a google for orange skin or carotenemia Nil Einne 14:10, 20 March 2007 (UTC)

Carrots contain carotinoids, which are pigments, also responsible for autumn leaves and beetroots :) A lot of flamingo's food contains carotinoids, which is why they are pink :) If it works for them, it is likey to work with other animals too :) HS7 14:17, 20 March 2007 (UTC)

This isn't quite the same, but a lack of iron leads to paler skin :) HS7 14:32, 20 March 2007 (UTC)

We have Sunny Delight in the US too and everytime a girl drinks too much and becomes orange she gets a five second blurb on the news. [Mαc Δαvιs] (How's my driving?) ❖ 15:28, 20 March 2007 (UTC)

Hilariously, people here went through a phase of thinking that Sunny Delight was some sort of 'health drink'. There were a few stories in the press about it making kids' teeth fall out too... ;) --Kurt Shaped Box 16:02, 20 March 2007 (UTC)

That's the way they advertise it, sadly. Dump a bunch of corn syrup in, add 1% juice and dump seven packets of ascorbic acid into it and you have a 100% VITAMIN C SPORTS DRINK THAT'S COOL AND HEALTHY! -Wooty Woot? contribs 23:10, 20 March 2007 (UTC)

That's 'cause it is :) [Mαc Δαvιs] (How's my driving?) ❖ 18:15, 21 March 2007 (UTC)

CRO

how a cro can be used to measure L,C,and self capacitance of an inductor?

You'd really need a signal generator as well. Beyond that, all that's necessary is an impedance bridge and some simple linear algebra. -- mattb @ 2007-03-20T13:23Z

What is a cro? A raucous bird with its final consonant amputated? A (something) (something) oscillator? A cathode ray oscilloscope? Something that goes with Magnon? Edison 14:09, 20 March 2007 (UTC)

An oscilloscope could obviously measure the change in electric current over time (given a known source voltage and source resistance). This would allow you to calculate the L and R components of the inductor. (A square-wave or pulse generator might make this easier by allowing you to create a repetitive waveform.) For self-capacitance, I think you'll need to identify the resonant frequency and this means the use of an appropriate signal generator. Presumably, this is a homework question so I'll leave it to you to work out the details of test-circuit arrangement and mathematics.

Atlant 15:58, 20 March 2007 (UTC)

Yeah, you could manage without a signal generator, perhaps by generating a step function of sorts with a good switch ('twould need to have nearly no contact bounce). Even so, methinks this is less precise than methods using a signal generator. -- mattb @ 2007-03-20T21:50Z

I assume you want to measure separately, some inductance, some capacitance, and then the self capacitance of an inductor. There are some equations to help on this:

e = L di/dt

i = C dv/dt

f= 1/(2pi* sqrt LC)

So if you applied aknown di/dt to an inductor and measured the voltage, you could find the inductance.

Also, if you provided a steady current to a capacitor and measured its dv/dt you could calculate its caopacitance.

The third is a little more tricky, becuyase you have all 3 elements in the equivalent cct. Inductance, capacitance and resistance. Agree with Atlant, you need to find the inductance and then the self resonant frequency. You can then calculate the self capacitance.

8-)) —The preceding unsigned comment was added by 88.109.124.137 (talk • contribs).

Well, thinking a bit about what mattb was saying, I guess I was presuming some sort of electrical "impulse" generator, even if it was only a switch connecting the voltage source. A storage 'scope would be handy, allowing the observation of single-shot events. Otherwise, some sort of relaxation oscillator would be useful so you can have repetitive events. (In some old 'scopes, the horizontal trace signal was externally available and could be used!) Given an impulse, I guess you could evaluate the self-resonant frequency based on provoking ringing of the inductor; we used to test "flyback" transformers (television Horizontal output transformers) in that way. Then one could apply the various formulae.

Atlant 12:46, 21 March 2007 (UTC)

Blonde Hair/Blondes

a quastion on genetics. Do pepole with blonde hair(real ones) have to posses other blonde facial hair : as eyebrows , beards and so on ? —The preceding unsigned comment was added by 82.81.145.66 (talk) 16:15, 20 March 2007 (UTC).

No. Body hair is often a different colour from head hair. Indeed, most natural blondes will have darker body hair. Rockpocket 17:23, 20 March 2007 (UTC)

Spelling note: Hair is blond, not "blonde". A blonde is a woman with blond hair. A man with blond hair is a blond (no "e"). --Trovatore 17:28, 20 March 2007 (UTC)

If anyone's curious, Blond#Etymology.2C_spelling.2C_and_grammar explains some of the spellings. -- Diletante 17:51, 20 March 2007 (UTC)

There is a illness in which a person has their whole body hairs white or blond. cant recall the name but i know its because they lack pigment in their bodys which if exposed to to much sunlight can cause some painful and sometimes deadly sideeffects. Maverick423 17:37, 20 March 2007 (UTC)

Albino. Clarityfiend 17:49, 20 March 2007 (UTC)

Interesting to hear that natural blond(e)s often have darker body hair, Rockpocket. It would be enlightening to know more about the genetics of that. For example, I know that while the genes that code for red hair on the head are generally recessive to everything other than blond hair, the linked gene(s?) for red 'Grown-up hair' appear to be dominant. How does the blond head/ dark body fit? Skittle 18:17, 20 March 2007 (UTC)

The answers to those questions aren't known, Skittle. The only gene that has a number of commonly found alleles that are strongly associated with human hair colour is the MC1R gene. Loss-of-function alleles are strongly associated with red hair. In most non-human mammals, MC1R is agonised (activated) by melanocortin hormones (proteins derived from pro-opiomelanocortin) to produce black/brown eumelanin pigments. An alternative agonist of MC1R is Agouti signalling peptide (ASP), when it binds to MC1R the protein "switches" the cascade to produce red/yellow phaeomelanin. So in non-human mammals, by controlling the production of ASP and melanocortins (either in a autocrine, paracrine or endocrine fashion), the animals can make yellow/red or black brown hair. You can see how spatial control of these proteins could result in different hair in different parts of the body. Infact, this mechanism is known to control the dark back/light belly colouration seen in many animals.

So, it was tempting for pigmentation biologists to hypothesize that the same type of system controlled variable pigmentation in humans. However, there proved to be a problem with this theory. Firstly blond hair in humans is actually a form of "light" eumelanin rather than phaeomelanin (which produces red hair in humans). Its not entirely clear why this type of eumelanin appears blond, but its thought that variation in the structure of the pigment-complex alters its pigmentary properties. But this is why both blondes and brunettes often tan well, while red-heads don't. Also, ASP doesn't appear to be involved in human pigmentation at all, instead human MC1R appears to have a level of endogenous activity which is ramped up on binding to melanocortins, but not "switched" by an alternative agonist. The production of phaeomelanin (red hair) in humans results on the reduction of the endogenous activity caused by loss-of-function mutations. So, the genetics of dark/blond hair are not known at the moment. Neither is the exact mechanism behind the difference in head hair/ body hair colour in humans, but there are clues. Its thought likely that paracrine hormone production is involved, since body hair production increases, darkens and thickens as we become sexually mature and body hair is almost always darker than head hair in blondes, never lighter.

I'll leave you with an interesting finding from the human MC1R red-hair studies: it was found that there was a corrolation between being a heterozygote ("carrier") for a loss-of-function MC1R allele and having gingerish facial and/or pubic hair, when head hair was not red. I, myself, have a "touch of red" when I grow a beard (I'll spare you the details of my pubes). So I genotyped myself and, true enough, I have one allele that is associated with red-hair and one that functions normally. Why this heterzyogote effect applies only to the body is unclear, but a similar genetic heterozygosity (in yet known genes) may account for differences in blondes also. But, moral of the story: if both you and your partner do not have red hair, but do have ginger pubes, then the chances of you having a red-hair child is significantly increased. End of public service announcement (with apologies for the length of this reply). Rockpocket 19:17, 20 March 2007 (UTC)

Thanks. That was a little beyond my biology, but I got the gist, and I think I'll have to reread, looking things up. Oh, and the last bit was sort of what I was refering to above. Skittle 20:45, 20 March 2007 (UTC)

Just to make sure u are talking about facial hair. it is clear to me that the blond color don't appear on the whole body hair , but mostly blond pepole also have blond eyebrows and blonde beards , I never saw a blonde (convining enough) that has black eyebrows so I'll repeat the quastion , does blonds always have blond eyebrows and other facial hair. btw the thank you for the spelling remark , the reason for the mistake I guess is the fact that I don't live in a country where English is the native language .

Its all depends on how you define the colour "blond". True, I have never seen a natural blonde with black eye brows or beards, but there are plenty with darker eyebrows and beards than their hair colour. A lot of blond men will have reddish beards also. My wife is a natural blonde and has what I would call "light brown" eyebrows (she doesn't have a beard). That said, her eyebrows do tend to turn more blond in colour when she has been exposed to the sun for a period of time. Rockpocket 20:27, 20 March 2007 (UTC)

No, I have very blond hair and my eyebrows are quite dark. In fact, the carpet matches the drapes. On top of that, my beard is reddish brown (russet?). − Twas Now ( talk • contribs • e-mail ) 05:06, 21 March 2007 (UTC)

There's quite a lengthy article in a recent edition of Science covering this very topic.

Atlant 12:54, 21 March 2007 (UTC)

Just to complicate things- I used to have blond hair, but it has been slowly turning brown for the last 18 years, and I still have very light coloured hair on my arms, legs and moustashe, whilst the rest of my hair is much darker :) HS7 19:22, 21 March 2007 (UTC)

Splitting Hairs

I have very thick wavy hair and have the constant problem of split ends. It seems that no matter what I do, I just have a whole bunch of them. Then it got me thinking: Is there a genetic benefit for humans to have this condition? And while we are at it, was there a genetic benefit to have straight hair whereas in Africa, to have curly hair? —The preceding unsigned comment was added by Juliet5935 (talk • contribs) 18:15, 20 March 2007 (UTC).

In early humans (long long time ago when we still followed the rules of selective reproduction) hair could play two roles. It could provide a benefit, such as providing warmth is cold regions or shielding from the sun in hot regions. Also, it may be used for sexual attraction. In modern times, pretty much all humans reproduce with no regard for genetic fitness, so it doesn't matter anymore. --Kainaw ^(talk) 19:34, 20 March 2007 (UTC)

Whoa, there. Saying that "pretty much all humans reproduce with no regard for genetic fitness, so it doesn't matter anymore" is simply not true. It is true that what made one fit in previous generations no longer does so today--nearsighted people don't get eaten by the nearest tiger--but as long as there are variations among people, some will be genetically "fitter" for their environment and more likely to leave more offspring. The environment may have changed, and the rules of selection may be different, but just because they don't follow your notion of fitness doesn't mean they don't exist. grendel|khan 15:19, 21 March 2007 (UTC)

I pointed out "genetic fitness". The two primary factors that correlate to the number of children per woman are financial means and education level. Those with the most poverty and least education have the most children. Those with the least poverty and most education have the least children. It is a stretch to claim that genes are a major factor in poverty and education. --Kainaw ^(talk) 16:29, 21 March 2007 (UTC)

good control theory book?

I'm looking for a good book on Control theory, particularly PID controllers and their tuning. (I know the basics about these subjects, but would like to know more.) Something nicely practical, not merely abstrusely theoretical. Anyone got any recommendations? --Steve Summit (talk) 18:17, 20 March 2007 (UTC)

swollen legs

Hi, my mum's lower extremities(legs) ve been swollen for the past 5days now and she claims the problem is from her heart,she said her heart is not pumping well,that's why her legs are swollen.But i dont get it,please how is the swollen effect connected to the heart? couldnt it be edema nor blood cloth?please i need some clarifications on this and also the cause of the problem.(Note- is not a medical advice,is just to clarify my curiosity.) thanks

For starters, you can read up on congestive heart failure and interstitial fluid. Anchoress 18:44, 20 March 2007 (UTC)

Of course, she should definitely see a doctor in any case (I'm assuming my writing that doesn't violate the medical advice rules). $\sim$ Lenoxus " * " 19:03, 20 March 2007 (UTC)

See Eclampsia - often due to high blood pressure. Pregnant women are particularly prone to this. It's quite dangerous. But "See A Doctor" is the only advice we're allowed to give. SteveBaker 20:27, 21 March 2007 (UTC)

Daily intake of nuts

I've seen this so many times but now that I'm looking I can't find it. What's the recommendation for daily intake of nuts for health? Is it a handful, 30g, what? Anchoress 18:51, 20 March 2007 (UTC)

I can't find a simple answer from the USDA... here is information for the total meat/nut/bean consumption, but not specifically nuts. Nimur 19:32, 20 March 2007 (UTC)

Thank you very much for that link; I will bookmark it for use with other projects. What I'm looking for is the advice on nuts only (not legumes or other proteins) with regards to the beneficial qualities of nuts' omegas, other good fats, and other micronutrients. Anchoress 19:54, 20 March 2007 (UTC)

I don't recall ever having seen a campaign for "nuts". Unfortunately these days, a lot of dietary information seems commercially driven: meat, milk, eggs they all have "foundation" seem to go on about "recommended portions" but the truth is, there isn't one single food group which can't be substituted out of a diet, which may very much be the case for nuts. I personally don't eat a lot of nuts and I bet a lot of people don't ever eat nuts, in fact, there are people who are fatally allergic to nuts. So my guess is, there simply is no accurate recommended daily intake of nuts, as long as you don't exceed any other intakes such as 'oil' or 'salt' or whatever else. Vespine 21:57, 20 March 2007 (UTC)

You can get more than the recommended daily intake of nuts here at the reference desks...or were you talking about those nuts? Clarityfiend 02:16, 21 March 2007 (UTC)

Yeah I know, I think I've already OD'd today. Anchoress 02:31, 21 March 2007 (UTC)

Here is a ref from 2001:[6] that says an ounce (30g) of buts five or more times a week reduces risk of coronary artery disease by 25 to 39% (assuming you aren't allergic, of course).Edison 13:47, 21 March 2007 (UTC)

Yeah, that's exactly the kind of thing I was looking for. Thank you!!! Anchoress 18:26, 21 March 2007 (UTC)

surely it would reduce the risk even if you were allergic :] HS7 19:19, 21 March 2007 (UTC)

blood type and sub antibodies

I have Leukemia CML type. I was given a card that states I am:

Blood Group O  RH positive
Antibodies: anti-K-1

It is the anti-K-1 part that I do not understand the significance of.)

I am hoping some one will be able to explain to me what the importance of the anti-K-1 antibodies means.

Thank You, LL —The preceding unsigned comment was added by 74.13.56.147 (talk) 19:01, 20 March 2007 (UTC).

This appears to be medical short-hand for the Kell antigen system. You should surely verify with your doctor. You might want to get a more general idea from our blood type article. Nimur 19:35, 20 March 2007 (UTC)

I think it is the Anti-Kell₁ antibody. See Hemolytic disease of the newborn (anti-Kell). It is normally in infants. --Kainaw ^(talk) 19:41, 20 March 2007 (UTC)

METAR report

I have a METAR report that ends in RMK 6AC140 NOSIG. What does the 6AC140 mean? Thanks.

Do you mean the weather-related METAR? If so, does the article offer any useful info? Anchoress 21:59, 20 March 2007 (UTC)

Look, that answer is really not helpful. I'm asking because the article does not provide me with the answer, and I've been unable to find the exact information online. If you can point me to some information which does, that would be appreciated. —The preceding unsigned comment was added by 129.78.64.102 (talk) 23:44, 20 March 2007 (UTC).

Well now that I know that you mean the METAR I linked to, and you did read the article, I do have more info I could point you to, but I don't expend energy assisting people who don't accept my good faith efforts to help them in the spirit in which they were given. Apologies in advance for being off-topic and snarky. Undoubtedly someone else will be able to find the info I found to answer your question. Anchoress 01:03, 21 March 2007 (UTC)

May I remind you of the large block of text at the top of the page which asks users to "search first". Asking me to do the same and then claiming to have the necessary information and simultaneously withholding it from me, punishes me for actually following procedure and is contrary to WP:AGF. Do as you wish.

You're right, that was rude of me, and I'm sorry. In my defense, I have a horrible headache and probably shouldn't be posting at all. Anchoress 03:31, 21 March 2007 (UTC)

No harm, no foul.

What's the full METAR? I think there are some sites that can translate. Splintercellguy 00:02, 21 March 2007 (UTC)

Yes, but they do not necessarily translate everything, and its likely that not all remarks will be translated either. —The preceding unsigned comment was added by 129.78.64.102 (talk) 00:06, 21 March 2007 (UTC).

Hmm, I'm no expert, but googling "6AC140" yields METARs with similar string portion as yours. Splintercellguy 01:24, 21 March 2007 (UTC)

You don't get it. I want to know what 6AC140 translates to, not just METARS with that reported. For example, NOSIG in the above example means that no significant change is expected. What does 6AC140 mean? —The preceding unsigned comment was added by 129.78.64.102 (talk) 02:15, 21 March 2007 (UTC).

Okay, trying here. From this page, it has this line in the table for remarks:

6pppp - 6 hour precipitation in .01 inches

Perhaps this is what you want? I try to please :). Splintercellguy 04:20, 21 March 2007 (UTC)

Thanks, but I don't think that's it. The pppp signifies four similar characters, (eg VVVVSM is designates four characters for visibility plus an SM to denote statute miles) -- it's not very good syntax, but it's what they use. It still doesn't explain what the AC is and AC140 is five characters.

The only reference so far I can find to AC in METAR syntax is a reference to the could genus (ie alto cumulus). I'm still looking, though. --Cody.Pope 04:58, 21 March 2007 (UTC)

Thanks. I noticed that too, but it doesn't seem to fit.

Aight, I can't be totally sure, but is you look at this list of METARs and cross reference it with this list of cloud types, you'll notice that whenever a block of #XX### appears, as a remark, the XX matches to some type of cloud type. I can't tell you what the numbers mean, however. Hope that helps, it sure was interesting learning about METAR cause until right now, I knew NOTHING about it. So if you're about to fly a plane, don't trust what I just said (if I find more, I'll post it). --Cody.Pope 05:20, 21 March 2007 (UTC)

Actually, I think you're on to something. I think the last three characters are the flight level of the cloud. I still don't know what the first digit is for, though.

Ok, so if we buy the cloud type and flight level argument, you'll also notice that when multiple #₁XX#₂#₃#₄ blocks appear, #₁ of the first block is always smaller than #₁ of the next block -- so perhaps it's a distance in some-unit(?) till you encounter that cloud type along the flight path? --Cody.Pope 05:36, 21 March 2007 (UTC)

There could be multiple flight paths, could there not?

Ah yes, there could be. Some kind of directional marker? --Cody.Pope 06:12, 21 March 2007 (UTC)

6AC140 is very strange. AC is not in FAR/AIM handbook in METAR section. Could it be a plain language remark? I don't see AC as a weather code because it's too similiar to aircraft. That said, could it mean 6 aircraft 14,000 ft? I;ve never seen that in a METAR but it could indicate weather baloons or something related to the metar station. What was the METAR station that issued it and what was the full line? --Tbeatty 06:00, 21 March 2007 (UTC)

Perhaps, but I think we've narrowed down the XX portion as a cloud type, I've now found a bunch of METAR reports (from multiple locations) with the aforementioned patterns (ie #₁XX###, with #₁ increasing in each progressive block). --Cody.Pope 06:11, 21 March 2007 (UTC)

6 = Second lowest broken cloud layer. AC = altocumulus 140 = 14,000 ft. Closest I can find. Here is a good source. --Tbeatty 06:42, 21 March 2007 (UTC)

Yes, I thought that it may have been the cloud overage in oktas on the way home. Thanks to all!

Body heat - How's it done?

I'm curious as to the process by which warm-blooded animals actually create internal heat. I guess it's a chemical system of some kind but I'd like to know how it's done.Cuzzi 22:16, 20 March 2007 (UTC)

Read up on the process in the homeothermic article. Anchoress 22:24, 20 March 2007 (UTC)

You might also want to read up on the citric acid cycle and electron transport--VectorPotential^Talk 00:47, 21 March 2007 (UTC)

Thanks, folks. So - would the quick answer be that heat is a bi-product of the conversion of nutrients into energy?Cuzzi 01:18, 21 March 2007 (UTC)

Yeah. :-) That was going to be my answer but I thought you wanted something more detailed. Internal combustion engine. Anchoress 01:22, 21 March 2007 (UTC)

(EC) Well, "by-product" generally implies that something is an peripheral process, where as homeothermic (warm-blooded) metabolism depends on the elevated temperature to a large degree. If you said "body heat is a function of the conversion of nutrients into energy" you'd be pretty safe. -- MarcoTolo 01:25, 21 March 2007 (UTC)

One of the byproducts is carbon dioxide, amongst other things. For example.Vespine 04:09, 21 March 2007 (UTC)

I think the more important aspect, is that metabolism is the primary function, and that when the production of ATP(ie metabolism) stops, *that* is when you release heat by dissipating the energy built up by electron transport--VectorPotential^Talk 21:40, 21 March 2007 (UTC)

March 21

Bullet velocities and wound types

This question has been bugging me for some time, and I could never find the answer, so I'll ask here:

When a human is shot in the torso with a 9mm bullet from a handgun, what causes more damage to the body; the laceration of the bullet passing through the tissue, or the blunt trauma which creates internal bleeding, bruising, etc.? And does this change with other types of ammo, eg. 5.56, 7.62, .50 Cal? Thanks guys, --71.197.149.164 00:17, 21 March 2007 (UTC)

See the article on stopping power. There is also have a stub at wound ballistics, but it's not very thorough yet. Nimur 01:28, 21 March 2007 (UTC)

The subject you are dealing with here is terminal ballistics, that and the above articles seem to have a lot of overlap. Bullets in the 9mm range generally don't cause a lot of 'blunt force' or mechanical type damage unless they are hollow point. People under the influence of drugs like pcp, and even just very strongly willed people, such as those with special forces training can function quite normally with several bullet wound, as long as you can 'block out the pain'. Unless the bullet actually hits your spine, brain or heart, it's generally the bleeding and 'shock' and stuff that eventually kills you. Apparently it isn't actually that uncommon for someone to faint from shock when they are being shot at, even if they aren't hit by a bullet. Vespine 02:40, 21 March 2007 (UTC)

As for the second part, yes of course, bullet type, speed and mass has a massive impact of what happens if a person is hit. Typically the more mass in the bullet the more damage it will cause. Continuing from my post above, a 9mm bullet is considered survivable if you get treatment and you are not hit in the spine, heart or brain, definitely that is not true for a .50 Cal, I imagine anything but a hit to the extremities would be fatal. Vespine 04:13, 21 March 2007 (UTC)

It depends on a lot of things. Mainly, damage is related to how much energy can be imparted from the moving bullet to the body in the quickest amount of time. Hollow points are designed to expand when they hit fluid. This tends to slow them down very rapidly and the energy is transferred very rapidly from the bullet to the body. This limits how far it penetrates, though, so there is a tradeoff. The ideal self protection round would be a very heavy bullet that expanded when it entered the body and stopped with 0 velocity in the spine. Military rounds such as the 5.56mm NATO ball and 9mm ball round are designed to wound consistent with the goals of warfare. Police in the U.S. usually use a .40 cal hollow point which is designed to rapidly stop (i.e. very lethal) someone without overpenetration. --Tbeatty 07:11, 21 March 2007 (UTC)

Thank you very much, I am quite satisfied. 71.197.149.164 16:40, 21 March 2007 (UTC)

lisps(speech impediments)

I would like to know if the lisp (speech impediment) is hereditary? — Preceding unsigned comment added by 69.112.118.126 (talk • contribs) 01:48, 21 March 2007 (UTC)

Physical lisps (as opposed to learned behaviour) are normally caused by physical issues. Thumb-sucking and missing teeth are usually attirbuted, but so can hereditary facial features. So, for the most part, it is not hereditary, but can be. --Kainaw ^(talk) 02:19, 21 March 2007 (UTC)

Travel to the Asteroid Belt

How long would it take to travel to the asteroid belt using minimal energy and current means? Say, the inner edge. I can't find a good distance for it anywhere.-- ×××jijin+machina | Chat Me!××× -- 06:56, 21 March 2007 (UTC)

• I think here is got it at about 4 months going 32,400mph http://www.spacetoday.org/SolSys/ThePioneers.html -- ×××jijin+machina | Chat Me!××× -- 07:02, 21 March 2007 (UTC)

That would be if you were just passing by. If you wanted to stop there, you'd have to decelerate, so it would take a good deal longer. Clarityfiend 08:19, 21 March 2007 (UTC)

You could decelerate once you got there, but that use much more fuel. Think outside the box 11:01, 21 March 2007 (UTC)

Our article on Hohmann transfer orbit says that it is "almost always the most economical way to get from one circular orbit to another". It also gives a formula for the time taken for the transfer. Plugging in the numbers, and assuming that the inner edge of the astreoid belt is at about 2 AU, I get a transfer time from earth orbit to the asteroid belt of about 340 days - say 11 months. Gandalf61 11:29, 21 March 2007 (UTC)

Enzymes

Does anyone know who discovered enzymes? Mattyatty 13:45, 21 March 2007 (UTC)

From Enzyme: As early as the late 1700s and early 1800s, the digestion of meat by stomach secretions[2] and the conversion of starch to sugars by plant extracts and saliva were known. However, the mechanism by which this occurred had not been identified.[3] [...] In the 19th century, when studying the fermentation of sugar to alcohol by yeast, Louis Pasteur came to the conclusion that this fermentation was catalyzed by a vital force contained within the yeast cells called "ferments" [...] In 1878 German physiologist Wilhelm Kühne (1837–1900) coined the term enzyme, which comes from Greek ενζυμον "in leaven", to describe this process. The word enzyme was used later to refer to nonliving substances such as pepsin, and the word ferment used to refer to chemical activity produced by living organisms. Does that answer your question? grendel|khan 15:15, 21 March 2007 (UTC)

Permanent magnets drain

is it true that if a permanent magnet held against another permanent magnet with the same poles facing for a long period of time they will lose their charge ? is there any exception to this ? and would this ocur in a system where both poles face each other very often but then move away from each other? clockwork fromage —The preceding unsigned comment was added by 216.113.96.124 (talk) 15:00, 21 March 2007 (UTC).

Permanent magnets vary in how "hard" they are. "Soft" magnetic materials can be easily depolarized/repolarized by an external magnetic field whereas "hard" materials are harder to depolarize/repolarize. Essentially, there's a minimum magnetic field needed to change the polarization of any given permanent magnet. Some things help cause repolarization: Heat (see Curie point) and ordinary mechanical shock and vibration (which jostel the individual atoms and allows them to flip to conform to the new magnetic field).

It's unlikely that two identical magnets unvibrated and at ambient temperature would depolarize each other.

Atlant 16:04, 21 March 2007 (UTC)

so theoricaly, if a device relied on magnetic as its source of power it would never run out right? clockwork fromage

The problem with that, assuming you want to use electricity, is that an electric generator has to rotate, whereas a magnet will only move things one way by itself :( HS7 19:18, 21 March 2007 (UTC)

Energy must be conserved. If you tried to extract a meaningful amount of power from the apparatus as you described, the magnets would rapidly demagnetize. They are not an infinite source of energy. In simple problems, they can be treated as constant sources of magnetic flux but in reality they will run out of energy if you extract it. Nimur 19:50, 21 March 2007 (UTC)

Normal permanent magnets could not be "drained" in such a fashion; they are in a lower energy state when they are magnetized than otherwise. I think you would just never find a way to extract anything from them. --Tardis 21:34, 21 March 2007 (UTC)

Magnets are not like batteries - they don't store or produce energy - so they don't "run down" in the sense that a battery might. However, they can get demagnitised under various complicated situations. The idea that you could build a motor that used the 'power' of magnets is an old one - but this won't work - magnets simply aren't like that. However, that doesn't stop various 'nut jobs' from imagining that this is possible. SteveBaker 20:22, 21 March 2007 (UTC)

In spite of everything written above, magnets really do get weaker if you store them with an open magnetic circuit (or, worse, with a closed-the-wrong-way magnetic circuit, like the original poster was describing). This effect can be practically significant. Many types of permanent magnet motor cannot be disassembled without ruining the magnet. (When the motor is assembled, other parts of the motor short out the magnetic field.) This is also the reason why permanent magnets are sometimes stored with an iron "keeper" across the poles.

And yes, conservation of energy holds. No perpetual motion. —The preceding unsigned comment was added by 24.91.135.162 (talk) 20:42, 21 March 2007 (UTC).

Refrigerators

How do the doors on refrigerators seal? Most modern fridges have that rubber gasket and when you close the door there is that signature "thoop" sound. But there doesn't seem to be a mechanism of any sort for a physical lock. Do the gaskets have magnets in them to hold the door shut? Dismas|^(talk) 16:26, 21 March 2007 (UTC)

Try it...take a piece of metal that sticks to a magnet and see if it sticks to the seal. DMacks 17:56, 21 March 2007 (UTC)

I'm fairly sure that most of these have a magnetic strip that runs the length of the seal. I've seen some high-end refrigerators that maintain negative pressure in the cabinet, but your home fridge probably isn't doing this. Note that in days past, mechanical latches were used to hold the door shut. -- mattb @ 2007-03-21T17:58Z

It's ferromagnetic [Mαc Δαvιs] (How's my driving?) ❖ 18:10, 21 March 2007 (UTC)

There should be a rubber strip around the edge of the inside of the door (as seen in this photo). If you cut it open (not a good idea unless you're throwing out the fridge anyway!), you can the magnet; it looks and feels like a long piece of smooth, flexible black rubber. The magnet serves two purposes: not only does it keep the fridge door shut, but it keeps the rubber strip pressed right up against the frame of the fridge, ensuring an airtight seal which increases efficiency and hygiene and keeps smells inside the fridge. Laïka 18:18, 21 March 2007 (UTC)

Cooking wine & spoilage

How long can a (large) bottle of red wine with screw-top last (with the top on) once opened? Would there be any valued added in putting some salt in it, as is done with commercial cooking wine? Thanks --64.56.107.126 16:49, 21 March 2007 (UTC)

genetic epidemiology questions

Hello, I was asked a question in the exams regarding genetic epidemiology please verify if my attempted solution is correct. please pardon if the question itself is incomplete , im quoting them from memory

• question1:

how many affected individuals with gene DD? given P(DD)= 1 P(Dd)=P(dd)= 0,0001.

couldn't solve this. perhaps this question is incomplete and it would be nice if you could insert the missing parameters and give a sample solution.

• question2:

given p(A)=.7 ,and there are 100 individuals what is fAa? (fAa is the conditional probability that an individual is affected given he has the genotype Aa)

attempting to solve: p(a) =1-.7= .3 assuming hardy weinberg equilibirium: p(Aa)= 2*.3*.7=.42

p(affected|Aa)= P(affected and Aa)/p(Aa) = .001/.42 =.0024

• question3:

given p(AA and affected)=.08, p(A)=.2 calculate p(affected and AA)?

attempting to solve: perhaps the question is wrong, maybe one needs to calculate p(affected|AA).

p(AA)= .2*.2=.04

p(affected|AA)= P(affected and AA)/p(AA)= .08/.04 = 2

probably a wrong answer, how can conditional probability greater than 1? -

Thank you very much for patiently reading through this list of questions. Iam perplexed, lecture notes are of little use, any help would be wonderful.

Thanks in advance.

212.201.73.208 17:05, 21 March 2007 (UTC)

Vasopressin and caffeine

i ave just read articles on Vasopressin and i was wondering if there might be a relation between long term caffeine intake and the brain chemical fonction of Vasopressin like agressivity to other males and bonding to sexual partners clockwork fromage —The preceding unsigned comment was added by 216.113.99.149 (talk) 17:48, 21 March 2007 (UTC).

I think you're a little ahead of the game. I don't believe such a link has been established, which doesn't mean it doesn't exist. However, the caffeine article states the over use and intoxication effects of caffeine, which has been around for a long time, and none of it seems to mention aggression or relationship issues. Vespine 21:58, 21 March 2007 (UTC)

There is known to be cross-talk between caffiene induced and vasopressin induced release of intracellular Ca2+ stores, somewhere at, or upstream of, an endoplasmic reticular Ca2+-ATPase. However, knowing there is a molecular interaction between the two signalling pathways is very different from knowing their behavioural consequences. Rockpocket 22:05, 21 March 2007 (UTC)

Nucleur Bombs

Hello,

On the British Vanguard am i right in thinking that there are 48 warheads on each sub and that each warhead in 100x more powerful than the bomb dropped on Hiroshima?

If so what would happen if they were all targeted in the middle of, say, London. What would be the scale of damage?

Thanks, --12345 wiki 20:29, 21 March 2007 (UTC)

Submarines of the Vanguard class can each carry 16 missiles, each missile can have up to 8 warheads, each warhead is either 100 kilotons or 475 kilotons - depending on which type of warhead is selected. The Hiroshima bomb was between 13 and 16 kilotons. So the sub carries 128 wardheads - each of which could be around 30 times the power of the Hiroshima bomb. Just one of those warheads would be more than enough to reduce the whole of central London to rubble. SteveBaker 21:34, 21 March 2007 (UTC)

I always wonder about threats to drop a zillion nukes on some specific site...like here, would 127 more do much more damage other than a deeper hole and more fallout? DMacks 21:40, 21 March 2007 (UTC)

(afer edit conflict)According to the article, it had 12 missile tubes capable of firing the trident missile which has a maximum payload of 3.8 megatons, the bomb dropped on Hiroshima was 13 kilotons.. It's hard to speculate the extent of the damage caused by a weapon like this and a description is probably impossible for a human to even fathom. Imagine this, a circle in the middle of London maybe 3 kilometres in radius is a crater in the ground, a circle 8 km in radius most buildings are levelled and even 20km windows are blown out, there is moderate damage to buildings and there are still fatalities. The nuclear explosion article is quite good. Now I am become death, the destroyer of worlds. As for the multiple nuke scenario, I don't think the "blasts" would add up, but there would definitely be an effect on fall out. The radioactive material comes from the blast it self, so more blasts, more radioactive material. I'm sure the big glass crater in the ground would reduce the amount of material gicked up in each subsequent blast but it would still add. Vespine 21:47, 21 March 2007 (UTC)

You're right about the 48 warheads (that's what Nuclear weapons and the United Kingdom says), but not about their yield. That article indicates the British bombs are similar to (or perhaps derivatives of) the US W76 warhead, which has a yield of 100 kilotons. The Fat Man (Nagasaki) bomb was around 21 kilotons, and Little Boy (Hiroshima) 16 kilotons (max). So Vanguard's warheads are maybe six times as powerful as Hiroshima. There's really no military need to make ones larger than that: you'd just end up digging a deeper hole. Atomic bombings of Hiroshima and Nagasaki says the area of total destruction at Hiroshima was about 2 miles across - lets guess that a 100kt bomb maybe destroys 3 miles across (like anything, more power gives diminishing returns) - that's around 9 square miles. That's per warhead. Now you wouldn't just launch all your warheads to one location, or all at one time - they'd all blast one another (what the nice nuclear men call "fratricide"). So you'd launch them over a space of a couple of hours, and you'd spread out their targetting so their effects would be maximised. 48x9 is about 400 square miles, or around 2/3s of Greater London would (in some evil-optimal scenario) be entirely destroyed. But really this is total overkill - five or six explosions, spread across the central section of the city, would be enough to horribly devastate it and kill maybe a million people. That's why Britain feels it needs only one sub at sea at a time - even accounting for losses due to (largely non-existent) missile defenses, those 48 warheads around enough to kill at least ten million people in any enemy country. I really cant for the life of me figure out why the US thinks it need 14 Ohio class subs (each with more tridents and far more warheads than the Vanguard boats) and why the Russians think they need 10 Borei class submarines. Darryl Revok 21:51, 21 March 2007 (UTC)