Wikipedia:Reference desk/Science

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January 9

How to find a reference...?

How do you find a reference for or locate the manufacture of a Hall effect switch or sensor like one designated as an F41.5Gc? -- Barringa 08:32, 9 January 2007 (UTC)

Try Honeywell SS41. -- 71.100.10.48 02:55, 12 January 2007 (UTC)

Standard taper ground glass joints (glassware): ISO vs. US

I'm trying to understand the difference between US and ISO standard taper (ST) ground glass joints. Are they more or less the same? Both using a xx/yy notation to describe taper diameter and length in mm? Would a ISO ST 29/42 and US ST 29/42 be identical? --Alf 08:02, 9 January 2007 (UTC)

It is possible to work with both at the same time. The US stuf is longer, but has the same diameter at the wider side. The people blive that this is better, but only in an ideal enviroment.--Stone 09:12, 9 January 2007 (UTC)

Thanks for the clarification. If you have the time, do you think you could incorporate some of your knowledge about the difference of these two standards into the Ground glass joint#Conically-tapered joints article? --Alf 09:44, 9 January 2007 (UTC)

Sorry this was for US-long the US is shorter than the ISO but still combinable, as long as the rest of the joint is not in conflict with some parts of the glas aperatus.--Stone 10:52, 9 January 2007 (UTC)

Importance of academic degrees

How important are academic degrees nowadays? Are Ivy league degrees worth the money? —The preceding unsigned comment was added by 132.231.54.1 (talk) 12:54, 9 January 2007 (UTC).

It depends on the field and location. For example, a degree from The Citadel doesn't mean much, unless you live near Charleston, South Carolina. If you do, it is an easy way to get a nice job at most of the local companies. I am a software engineer - which requires a degree to get any respect. I'm switching professions to become a college professor, which requires a graduate degree to even be considered. So, you can see that academic degrees are important in some areas and the college you go to is also important in some areas. --Kainaw ^(talk) 13:52, 9 January 2007 (UTC)

Having an undergrad from a very well known university can definitely get your foot in the door. Most employers respond very positively to "Yale", "Harvard", "Berkeley", etc. as your place of origin. Once you drop down a bit from a world-reknown place, I am not sure that the name means as much to most people. With more advanced degrees I think it depends on what your ambitions are. You are not going to get called up to Wall Street if your business degree is not from some place well-known, but if you weren't aiming at that then it probably matters less. If you are trying to break into academia, having a PhD from a very well known program will definitely make sure you are on the short-list of serious job candidates wherever you apply, which won't automatically get you a job but it sure does help. That's my perception of it, anyway. In most cases the degrees just act to impress upon others what sort of serious candidate you are — you've still got to perform to be successful. --24.147.86.187 15:28, 9 January 2007 (UTC)

If the whole idea of going to university or college for its own sake doesn't strike you as at least somewhat intriguing, you may want to consider your ultimate reasons for going in the first place. Money, a job, a house, a spouse, kids...? Vranak 16:25, 9 January 2007 (UTC)

I chose to go to university so I could meet new people, go somewhere different, spend some time away from home, and learn something I haven't studied at school. The slightly increased chance of getting a job is just an added benefit.Hidden secret 7 19:34, 9 January 2007 (UTC)

Are there some things you can not do if you do not have a degree? Going to university or college is like an operating system for your computer. Going to Havard will probably all a lot of bells and whistles even if you do not graduate like it did for Bill Gates who's parents socialized with the head of IBM, etc. Contacts might be equally or more important than a degree going by the number of millionaires with an 8th grade education or less. Instead of doing basic research in a university/government sponsored lab you could create such a lab of your own Jim Walters. Having a degree - even an incomplete one, is under any circumstance probably better than not having one at all. Barringa 21:25, 9 January 2007 (UTC)

If you are going to do any great work in your life, it will probably not hinge on your having a degree. You might get a degree in the course of doing great work, but it's not like you will say to yourself after four years of college "Ah, I have my degree! Now my life begins!". Vranak

Having a degree is like having a car... you can't walk or ride a bicycle on some roads or get to where you are going as fast. 71.100.10.48 03:00, 12 January 2007 (UTC)

As Mark Twain said, "Never let your schooling interfere with your education." — Michael J 18:02, 21 January 2007 (UTC)

Cosmic inflation

I'm attempting to write an essay on cosmic inflation, but am having a little trouble understanding the jargon in the article - I've interpretated the majority of it, but I don't see anything explaining why inflation ceased - did the decaying vacuum energy simply reach its new, more stable minimum?

Thanks, 130.209.6.40 13:40, 9 January 2007 (UTC)

Didn't it slow down because of gravity attracting everything towards everything else, and now they think the whole thing is going to collapse on itself.Hidden secret 7 19:31, 9 January 2007 (UTC)

Your guess is pretty much correct. The inflaton (no, I haven't missed an i there) field reached a lower, stable potential. What sort of level is this essay supposed to be? And are you versed in quantum field theory?

To be honest, I don't think I have to be that deep - it's for a group report on Cosmology, and the other topics are "easy" things like the expansion of the universe, and the CMBR, so I think it's more hand-wavey than anything else. I've got it pretty much done, with a summary of the process, some of the objections to the HBB model it explains, and now I'm just looking for criticisms. I've only been able to find two in my references, but the Cosmic inflation article doesn't really seem to have any. I've got that it predicts the wrong value of Ω₀, and that the mechanism for why it stops isn't understood...but I'd really like more than that. Am I missing any crucial ones? I fear I'm in over my head... Icthyos 17:12, 10 January 2007 (UTC)

Other criticisms I can think of off the top of my head are: If inflation did happen why haven't we detected any cosmic strings? Why is there still a little bit of inflation going on today? Why is the energy of free space so much higher than that required by inflation? —The preceding unsigned comment was added by 86.145.254.48 (talk) 19:27, 11 January 2007 (UTC).

trivias about sounds...

^{Superscript text} _could you please help me to find some of the most interesting trivias about sounds?,got a hard time seeking for some,;p 203.215.116.127 15:22, 9 January 2007 (UTC)heartbreaker203.215.116.127 15:22, 9 January 2007 (UTC)

The russians discovered that people can hear a much higher pitch of sound if whatever is producing the sound is touching the person hearing it.Hidden secret 7 19:28, 9 January 2007 (UTC)

The Mosquito is quite an interesting sonic device, and there's also ultrasound, used for medical tests. StuRat 04:08, 10 January 2007 (UTC)

Why does catnip have that kind of effect on cats?

Hi all. I was wondering why catnip has that kind of effect on cats? I was reading up in your article, but could find no mention of what the actual mechanism was. Maybe one of you biology-savvy individuals could explain it better? Much help appreciated ! Xhin 15:28, 9 January 2007 (UTC)

The mechanism actually isn't very well understood, though some aspects of it are. The cat's receptor for nepetalactone is in the vomeronasal organ, located above the feline palate, and the response is similar to a sexual response, but the exact nerve pathways involved are not, I think, known. - Nunh-huh 18:14, 9 January 2007 (UTC)

Following on from Nunh-huh, at the vomeronasal organ (VNO) the nepetalactone is hypothesized to bind to one or more G-protein coupled receptors on the surface of sensory neurons which are found in the sensory layer of the organ. Via a signal transduction pathway (probably involving a G-protein and a transient receptor potential channel) an influx of calcium ions occurs creates an action potential along the axon of the neuron. The sensory neurons of the VNO project to a region of the olfactory bulb called the accessory olfactory bulb where multiple neurons (each apparently expressing a single receptor type) synapse at special neuropil called glomeruli. Here the neurons synapse with mitral cells which, in turn, project to various brain loci, including the amygdala, where the signals are integrated into behavioural signals. It is at this point the pathway enters a bit of a black box. However, there is some evidence of projections to the hypothalamus, which in turn regulates a neuroendocrine response via the pituitary. These hormones would mediate the "sexual response" noted above. That is "how" it is thought to work, "why" is currently unknown. Though one might speculate that the chemical probably hijacks the pathway normally influenced by a cat pheromone. The fact that it only elicits such a response in a proportion of cats - and that it is such a dramatic response - suggests that a genetic element might be involved that is enriched for in domesticated breeds. Rockpocket 08:31, 10 January 2007 (UTC)

Mewow! Perhaps you could add that to the catnip article?--Shantavira 09:02, 10 January 2007 (UTC)

Evolution of organs

How do organs evolve when the intermediary step to the organ seem to bring no advantage to the animal? For example, take the elephant ear. I understand how useful their large ears are in present-day elephants, but I don't see how ancestral elephants with slightly bigger ears have advantage over others. For example, how can an ancestral elephant with an ear that's one milimeter larger in diameter be more successful than other elephants with a one milimeter smaller ear? I can understand how other organs, such as eyes, vertebrae ears, limbs, etc. would have advantageous intermediary forms, but not in organs that seemingly don't have such advantage. Is it genetic drift, or something else? Thanks in advance for any insight.128.163.224.198 19:02, 9 January 2007 (UTC)

An elephant's ears are an important cooling system for the animal. Consider larger ears==>better cooling==>better survivability. Ear size differences among different species correlates with climate. But also, how do you know the change was milimeter at a time? Perhaps the gene that regulates ear growth became virtually non-functional via a point mutation, leading to massive overgrowth? DMacks 19:39, 9 January 2007 (UTC)

Oh, to add more, a better example would be the evolution of bird wings, rather than elephant ears. How can a partially developed wing be useful to the animal?128.163.224.198 19:06, 9 January 2007 (UTC)

They now believe the appearance of bird wings was spontanious, caused by the spread of recessive alelles through a population of reptiles. I can't remeber what this is called now, but you might be able to find out more looking up evolution, or archaeopteryx.Hidden secret 7 19:26, 9 January 2007 (UTC)

One possible mechanism: Small wings are good for improving traction while running, larger wings are better, absurdly large wings give the ability to glide and later fly (birds).

Another mechanism: small skin flaps between limbs are good for longer jumps. Larger skin flaps improve on this (flying squirrel). Very large skin flaps give the ability to fly (bat). --Carnildo 19:52, 9 January 2007 (UTC)

Feathers#Evolution says that feature probably evolved for insulation, not for flight, and then got "hijacked" for an entirely different purpose. So they wouldn't have to suddenly be flight-worthy all at once. Clarityfiend 20:56, 9 January 2007 (UTC)

So the elephants genes were mangled and their ears suddenly went mad? Does the fossil record support this? I don't have a museum in my house, but the internet might know.Hidden secret 7 20:06, 9 January 2007 (UTC)

For example, how can an ancestral elephant with an ear that's one milimeter larger in diameter be more successful than other elephants with a one milimeter smaller ear?

That's easy to explain. Think about heatsinks for CPU in ordinary PC. The earliest CPU for PC have no heatsink. The problem is that those CPU cannot exceed a certain rate of heat release without failure. The first heatsinks are tiny (compare with today), but they give the those CPU evolutionary advantages over those without heatsinks because they can run "hotter". The next heatsinks are slightly bigger and so even more evolutionary advantages. Over the years, the heatsink got bigger and bigger. But they hit an evolutionary roadblock. So the next mutation are heatsinks with fans. The first heatsink fans are small and weak. Then they evolve bigger and faster. So you see, every small steps in evolution gives the animal advantages. Every millimeter counts!!! 202.168.50.40

NOTE: I'm the topic creator, just answering with a different computer/IP address here. Back to the question; I can understand how "every millimeter counts", but in the case of elephant ears I question its impact as a whole. There might be other environmental pressures that trump whatever advantage a milimeter brings (or not really "trump", but make them almost insignificant that the "big ear genes" don't get passed down that many more than small ear genes). For a trait to be passed down at more frequency than others, it must have absolute advantage over others. So, say that there are vicious predators of ancestral elephants. In this case, elephants with longer and stronger legs will survive better and increase its genes in the population. But, those with a milimeter larger ears will not pass more genes because the biggest pressure in the species will select those with better predator-evasion physique, not, say, temperature regulation that the large ears bring. And remember, the ear is only a milimeter larger; while it is an advantage to the animal, it doesn't have that big of an advantage for its genes to be passed down more frequently due to other environmental pressures.

Take another practical example, this time relating to us humans. We acknowledge that better vision makes a better organism. So even though we say that better vision is an advantage, how come we don't have everyone with "super eyes" compared to previous generations? (Our vision as a species probably has stayed more or less the same over the millenias. Pure speculation, but I don't see how it doesn't make sense). That's because, I think, there are other outside factors that selects other things, but not so much the vision. Early hominids with better communication skills, intelligence, and stronger legs had better chance to group together and evade predators; there are those with better vision, but the vision that they have don't offer too much of an advantage (if they don't have the three factors I listed in the previous sentence) that their genes become more frequent in future populations (again, because environmental pressures selected other things beside better vision).

So the only scenario I can think of that allows gradual enlargment of the elephant ear is if the environmental pressure demands larger ears and less everything else. (I guess I just answered my question there :-) ) Is what I'm saying a part of any specific evolutionary theory, so I can look it up? 128.163.80.164 22:23, 9 January 2007 (UTC)

"Environment" means more than just the physical environment, of course; it can also mean "mating pressures" and other things which come under the rubric of sexual selection. As to your question about the "less everything else," what you are really getting at, I think, is that the need for big ears needs to be evolutionary such an advantage that not having them becomes a disadvantage. There are rather complicated statistical models describing how strong these sorts of pressures need to be either way, if I recall. Additionally it is worth remembering that things need not evolve together at all—independent evolution of certain traits can come together in a favorable way as well, and some traits need not even evolve perfectly at all. --24.147.86.187 03:33, 10 January 2007 (UTC)

NOTE: I'm the topic creator, just answering with a different computer/IP address here. You hit my point right on the head there. So, would my analysis be correct? And is there any specific, named theory that describes what I talk about (by that I mean the evolution of a specific trait vs. relevant outside pressure)? From my limited knowledge of evolution, what I described seems to make the most sense to me in the evolution of organs, so if anyone can point out to me other sources regarding it, I'd appreciate it. 128.163.174.129 21:24, 10 January 2007 (UTC)

The questions you are asking are typically grouped into a school of thought known as Irreducible complexity. I think you will find the best answers to your questions in that article, as well as Evidence_of_evolution#Evidence from comparative anatomy, Evidence_of_evolution#Vestigial organis and especially Evolution of the eye. -- dpotter 21:19, 9 January 2007 (UTC)

NOTE: I'm the topic creator, just answering with a different computer/IP address here. Thanks, Dpotter. Just to note, however, I believe that evolution and common descent are the best scientific explanation of speciation. I'm not too fond of IC, ID, Creationism or anything like that in terms of providing the best scientific explanation of diversity. My question here is not so much to question evolution in general, but is about my curiosity in the specific mechanisms of evolution that may have occured.128.163.80.164 22:23, 9 January 2007 (UTC)

No one has yet mentioned the OBVIOUS ONE!:) Elephant ears of course would have started evolving for the same reason as human ears, for better hearing!! Which has very obvious advantages, hearing predators and such.. Vespine 21:34, 9 January 2007 (UTC)

I've heard that it actually takes only a very small advantage to drive change. Vultur

To add to what others have said, there is lots of variation in any population; consider that it's not hugely unusual to find adult human males taller than 2m (6'6") or shorter than 1.65m (5'5") - a difference of more than 20% in height. Consider also that large animals have a smaller surface-area to volume ratio and so are more likely to struggle to dissipate heat (as in a simple model - heat is generated by every cell in the body -> roughly proporional to volume. Heat can be dissipated only by the skin around the edge of the animal). Elephant ears provide a cooling mechanism for the elephant. Larger ears allows an elephant to lose heat more quickly. What if that means that an elephant can run further/faster from predators without overheating? That will certainly give a large-eared elephant a definite advantage over smaller-eared ones and increase the survival rates. It needn't be millimeter changes in ear size - if human heights can vary by 20%, so could elephant ear sizes. So if the survival rates of large-eared elephants increases (even slightly), then there is a trend for large-ear genes to be passed on to offspring in favour of small-ear genes. Over many hundreds of generations, larger-eared elephants become the norm in the population Richard B 14:56, 15 January 2007 (UTC)

Chemistry Trouble

Hey, I'm revising for Chemistry and have just done a past paper for my AQA Chemistry A-Level. I've just tried the AQA website, and it's not working! My friends have also found it down. I was hoping that you'd be able to confirm whether I'm write for this question.

You're given the formula for the decomposition of Lead(II)Nitrate

2Pb(NO₃)₂ → 2PbO + 4NO₂ + O₂

and then told to work out the number of moles using the Ideal Gas Equation, being told that the sample was heated until decomposition was complete. Using the information provided you get 0.00361 mol (to 3 s.f.) (500K, 100kPa, 1.50x10^-4m³, T=8.31JK^-1mol^-1)

The followup question asks for the number of moles of NO₂ and then the mass.

How would you tackle this followup. I'm pretty confident but want to check!

Thanks, --86.137.233.160 19:50, 9 January 2007 (UTC)

I think you are not giving us some info. You are looking for moles of what? You obtained .00361 mol of what? And what was the info provided? Maybe a more word-for-word description of the problem is in order. --Bennybp 21:55, 9 January 2007 (UTC)

unfitness test

This isn't about medical advice, I am just interested in knowing weather it is normal when my pulse rate gets over 220 that it feels like someone is squeezing my trachaea, my whole body is pulsating as blood flows through it and air is forced our of my lungs every time my heart beats. Is this beacuse I am very unfit, or just the usual side effects of a high pulse rate?Hidden secret 7 20:02, 9 January 2007 (UTC)

I would suspect that the latter is a symptom of the former. Vranak

Do you know how on all those fitness machines, they say "See doctor before commencing any fitness program!"? I think that is good advice. --Zeizmic 23:35, 9 January 2007 (UTC)

If your heart rate gets above 220 often, you're probably unfit. Regardless, try to exercise more than you do now, and see a doctor if you're worried. --Bowlhover 03:10, 10 January 2007 (UTC)

It has never gone above 180 before, and I have started exercizing more, which is why it was so high. I did the same thing again today and it seems slightly better. I hope.Hidden secret 7 13:46, 10 January 2007 (UTC)

Typically in exercise, your target heart rate should be 65-85% of your "maximal" heart rate. To calculate your maximal rate, take 220 minus your age. A heart rate over 200 in an adult is indicative of ventricular tachycardia, a potentially fatal heart rythm. You should probably talk to your doctor about your exercise regimin or about being tested with a Holter monitor. Andrewjuren(talk) 07:48, 11 January 2007 (UTC)

I don't think I have that, I hope not :( Is there any way to tell without seeing a doctor :? And I am not an adult yet :)Hidden secret 7 18:35, 11 January 2007 (UTC)

Galinstan?

Where can I find information on the liquid metal Galinstan? The wiki article did not have the physical properties I was looking for. (Viscosity, thermal conductivity, etc.) —The preceding unsigned comment was added by 216.182.144.119 (talk)

An MSDS is often a good source for physical properties. There's a link to one at the end of the galinstan article. DMacks 20:34, 9 January 2007 (UTC)

Two Hybrid Screening In Yeast

When talking about yeast cells used in two-hybrid screening, is it appropriate to call the yeast cell a 'host', 'model' or something else? --Username132 (talk) 21:06, 9 January 2007 (UTC)

Two-hybrid screening --JWSchmidt 04:26, 10 January 2007 (UTC)

Sorry but I don't think the article answers my question. As it happens I'm working on that article and that's why I asked the question (for a subheading). --Username132 (talk) 21:38, 10 January 2007 (UTC)

The plasmids are introduced into the yeast cells by a process that is generally called transfection. After the plasmids have entered the cells, the cells are called "tranfected cells". The tranfected cells are subjected to selection conditions: growth in a defined culture medium that only allows tranfected cells to survive if those cells can form a functional transcription complex formed by the physical interaction of two "transfected proteins". "Transfected proteins" meaning that they are proteins expressed from the plasmids that were transfected into the cells. --JWSchmidt 04:26, 11 January 2007 (UTC)

Elemental form

Is 3Co in its elemental form? 141.158.99.155 21:29, 9 January 2007 (UTC)

Do you mean Co₃? A substance that's in its elemental form has only one element in its molecules; it's not a chemical compound. Co₃ has 3 cobalt atoms, so the short answer to your question is yes. --Bowlhover 03:05, 10 January 2007 (UTC)

How would a molecule not be a chemical compound? A real question might be whether Co₃ is a naturally-occurring allotrope of cobalt. DMacks 07:49, 11 January 2007 (UTC)

If you think about band theory and all that, then technically any metal in the form M_n is still in its elemental form where M = any metal and n = any number of atoms. Therefore Co is in it's elemental form whether it is written as 3Co (ie three moles of Cobalt) or Co₃. It is certainly not an allotrope.

And a compound usually has more than one type of atom, or, if it is a p block element, more than one atom (eg O₂, CO, S₈, GaN, LiCl etc)

Stui 21:21, 17 January 2007 (UTC)

How's it done?

How was this done? http://ebaumsworld.com/2006/03/magnet.html Thanks!! Reywas92^Talk_Sigs 21:52, 9 January 2007 (UTC)

That's an example of a superconductor. The black material is superconducting below a certain temperature. I assume that's liquid nitrogen poured onto it, this lowers the temperature and causes it to superconduct. When a material superconducts it does not admit any magnetic fields. The magnet will therefore not approach within a certain distance depending on its strength. This causes it to hover.
Contrary to popular belief this is not quite how bullet trains work. They mearly use very good conductors, not superconductors. I hope this helps. —The preceding unsigned comment was added by 81.153.52.250 (talk) 22:45, 9 January 2007 (UTC).

• Clarification: The term "bullet train" is usually used for fast conventional trains. This person is talking about maglev trains. --Anon, Jan. 10, 07:42 (UTC).

How does the superconductor and the piece of metal stay a fixed different from eachother? —The preceding unsigned comment was added by 138.29.51.251 (talk) 23:09, 9 January 2007 (UTC).

Two answers: (1) The magnet settles downward until the upwards repulsive force from the superconductor becomes equal to the downward force of gravity, just like whenever a weight is placed on a spring, for example. If that were all that was going on, however, the magnet would probably slide off to the side as if it rolled off a ball. But it doesn't, so there is more going on: (2) You probably noted that the magnet appeared to become "stuck" at a particular point and orientation in space above the superconductor. This is because these are "type 2 superconductor|"type 2"]] superconductors, which do not exclude the magnetic flux completely, but instead allow a few thin tubes of magnetic flux ("flux vortices") to go through. These tubes tend to get stuck ("pinned") at defects inside the superconductor, and since the flux is connected to the magnet (in a sense) this makes the magnet "get stuck" too. --mglg_(talk) 02:18, 10 January 2007 (UTC)

The article for more information is the Meissner effect. X [Mac Davis] (DESK|How's my driving?) 17:45, 10 January 2007 (UTC)

Reversible Gas Turbines

Kindly explain what is a reversible Gas Turbine —The preceding unsigned comment was added by 213.130.123.28 (talk) 10:33, 9 January 2007 (UTC).

Question moved here from the Mathematics reference desk.  --Lambiam^Talk 21:52, 9 January 2007 (UTC)

This extract from a research abstract considers one definition, where the turbine can turn in the opposite direction to normal -

Aircraft gas turbine engines, as now configured for ship propulsion, are unidirectional in output rotation and, therefore, require the added complexity of a reversing transmission or a reversible-pitch propeller. This study explores the feasibility of a novel reverse-turbine concept which is configured to adapt to existing free-power turbine engines without additional clutches or separate drive trains. This device, termed the 'isolated reverse turbine,' is sized for meeting that most demanding maneuver for a fixed-pitch propeller-driven frigate or destroyer, namely, the crash reversal maneuver. The reverse-turbine concept would replace the function of the reversing gear or the reversible-pitch propeller; it could also complement electrically actuated reverse transmissions by eliminating the need for braking resistors and switches.

A turbine operating in reverse would of course be a compressor, but the design characteristics of the two devices are somewhat different.81.153.220.80 12:56, 10 January 2007 (UTC)

Reversible implies that the turbine has an efficiency of 1; that is it loses no energy to frictional or viscous effects, and there is no entropy gain. Thus, the process (not the turbine) can be reversed without violating the second law of thermodynamics. It has nothing to do with running the turbine backwards. -anonymous6494 16:54, 10 January 2007 (UTC)

Based on Google hits on the term and the contexts in which the term appears, it doesn't seem that "reversible" is used in the sense of the word in thermodynamics. --71.175.23.226 18:08, 12 January 2007 (UTC)

I see hits for both, but for the sake of argument let's assume we are talking about running a turbine engine in reverse (i.e. as a compressor). The problem with such an engine is that the blades are designed with the direction of flow in mind, so simply running the turbine in reverse will not produce the desired result. An engine designed to do both could be built, of course at the expense of efficiency. It is likely that the reversible turbine would be less attractive (at such low efficiency) than another system, such as an electric motor and battery. anonymous6494 03:14, 13 January 2007 (UTC)

Google hits on the term suggest that reversible gas turbines are most commonly used for ship propulsion. At least in the context of this U.S. patent, a "reversible gas turbine" is one that can reverse the direction in which the output shaft rotates (however accomplished). It's not about running a turbine in reverse and using it as a compressor. --71.175.23.226 13:37, 13 January 2007 (UTC)

Measuring rainfall

Why is rain measured in mm than mL? The Updater 23:22, 9 January 2007 (UTC)

See Rain gauge. --Zeizmic 23:32, 9 January 2007 (UTC)

Kind of like how you wouldn't measure how much snow there is by its volume. I suppose one could measure rain and snow in terms of volume, but that wouldn't be practical. How high those things are from the ground lets us know, for example, how bad a flood or a blizzard is.128.163.80.164 00:33, 10 January 2007 (UTC)

More fundamentally, of course you could measure in litres say, and now you compare the amount of rainfall you had with your neighbour, who also collected rain, but you collected it in a can and your neighbour in a giant tub. Of course she would have more, if measured by volume. Your tiny can could not even hold one litre. So to make this comparable, you have to take the surface area into account over which the rain was collected. And then you get, for instance, as the measure an amount in litres per square metre, L/m², and since 1 L = 0.001 m³, that unit of measurement equals 0.001 m³/m³ = 0.001 m = 1 mm.  --Lambiam^Talk 01:16, 10 January 2007 (UTC)

By the way, what Lambiam just did is called dimensional analysis, and it's a great way to figure why we use the units we use for several things. — Kieff 02:20, 10 January 2007 (UTC)

Like measuring pressure in mm too. :?Hidden secret 7 13:49, 10 January 2007 (UTC)

Pressure measured in terms of length is a reference to gravitational potential energy: height times the acceleration of gravity times the density of the fluid referenced (typically water or mercury) has units of pressure. So for mercury the conversion is (13.534 g/cm³)(9.81 m/s²)=133 Pa/mm. --Tardis 17:41, 10 January 2007 (UTC)

Most conventional pressure measurements are either in hPa (mbar) or in mmHg/inHg, for the reasons explained above. Titoxd^(?!?) 17:44, 10 January 2007 (UTC)

Thanks for the info. The Updater

sideways in time

Thanks to such science fiction shows as Star Trek we have an understanding of the concept of back and forth in time. But what might "sideways" (left or right) or "diagonally" or "spirally" in time look like? Anyone care to speculate? —The preceding unsigned comment was added by 216.176.54.133 (talk) 23:40, 9 January 2007 (UTC).

"Sideways" doesn't exist in one dimension. If we consider time as some sort of timeline, it can only have "backward" and "forward" directions. — Kieff 23:50, 9 January 2007 (UTC)

Being a creature that occupies four dimensions, which I am aware of at least, I find it really difficult to imagine what one dimension would be like. ;) Have you seen the Back to the future movies?? I think they explain sideways in time fairly well, more the sequels then the original. Basically, time is like a tree, from any point in time, there are an almost infinite number of branches of possible 'futures' that could happen depending on chance and choice. going forward you can only travel down the branches that span from the trunk of the NOW you are in, travelling sideways, you could end up on a branch that branched off BEFORE the now you are in. For example, travel sideways in time to the 2007 where the allies didn't manage to develop nuclear weapons and the axis powers ultimately took over the world. Vespine 00:20, 10 January 2007 (UTC)

Imagining one dimension is easy, you can only go one way. Like time, in this universe, or driving through a tunnel. Imagining multidimensional time is much harder. Philc _T^E_C^I 18:28, 10 January 2007 (UTC)

The way the OP asked the question, it seems he's interested in continuous movement in time, not "jumping". What you described is just jumping to a different timeline altogether. Assuming many timelines side by side, travelling completely "sideways" in time would just move you around the same instant in time, but in different alternative universes. Travelling diagonally, then, would make you pass through a different universe in each subsequent instant forwards (or backwards) in time. That wouldn't be very useful to observe. Unless, of course, alternative universes close to each other had a gradual change. If that was the case, you could see people walking in the streets slowly turning into intelligent chicken-like beings as you travelled diagonally along the alternative universes. — Kieff 00:35, 10 January 2007 (UTC)

Which raises the question, would it be unethical to catch these chicken-like beings, bring them back to our universe, and sell them (after some culinary processing) as Alternative Fried Chicken?  --Lambiam^Talk 01:21, 10 January 2007 (UTC)

From the realm of science fiction or modern physics, moving sideways in time would imply going to another of the nearly infinite number of alternate universes. At each instant, universes should branch out from each possible quantum event. Drop a piece of buttered bread, and it lands butter side up in one universe and butter side down in another. Drop 50 coins and there are universes where all 50 land heads up and every other permutation. Robert A. Heinlein wrote some fun sci-fi about such things. Edison 05:44, 10 January 2007 (UTC)

There is a classic science fiction story whose name escapes me now, about a Catholic priest who travels to another planet where he discovers a civilization of intelligent, peaceful dinosaurs which he comes to admire. But their entire existence begins to undermine his faith that only humans can have souls. User:Zoe|(talk) 18:16, 10 January 2007 (UTC)

Ah, it's A Case of Conscience, by James Blish. User:Zoe|(talk) 18:36, 10 January 2007 (UTC)

How about imaginary time? Also, Stephen Hawking wrote in his book Black Holes and Baby Universes about that I think. Something about time always moves forward, never backward, but we can go at an angle, as in the special theory of relativity. I suppose it just depends on what you put on the other axis, and if time is one dimensional or not. --Bennybp 06:17, 10 January 2007 (UTC)

This is only peripherally relevant, but watching the 2004 movie Sideways is an excellent way of spending time. JackofOz 02:34, 11 January 2007 (UTC)

January 17

Source of salt in ocean water

What are the sources of saline in ocean water?209.6.248.169 00:37, 17 January 2007 (UTC)Ed

Have you checked our article on sea water? — Kieff 00:50, 17 January 2007 (UTC)

Escalator handrails

Why do the escalator handrails often move slightly slower than the steps, requiring you to change your handhold periodically or risk falling backwards ? StuRat 01:13, 17 January 2007 (UTC)

HAH! Sturat?? I can't believe it! or has someone hijacked your account?? I've wondered this too, have you read the escalator article ;) Nah just kidding, but I found this under the 'safety' section: Handrail speed sensors — located somewhere inside of the escalator unit. These sensors are usually optical, they are positioned to sense how fast the handrail is going. In case of a drive chain/belt breaking, in order to protect the drive and people on the escalator, if the sensor notices a speed difference between the handrail and the steps it will sound an alarm... So, supposedly, a different drive operates the hand rail and the stairs, fancy that, and the difference in speed we've noticed is not enough to trigger the sensor. Vespine 01:27, 17 January 2007 (UTC)

Actually *scratching head*, i've re read the above and I don't beleve my self anymore, that says in case of the drive belt breaking implying it IS the same.. Back to the drawing board. ....Vespine 01:29, 17 January 2007 (UTC)

Yea, I hadn't even considered that they would have separate drives, and assumed they used a gearing mechanism to account for the handrail going slightly farther in one revolution than the steps, if that is, in fact, the case. The question is, how could they be off by so much that it's obvious ? This seems to be a common occurrence, too. StuRat 02:53, 17 January 2007 (UTC)

I've been thinking more and I think it must be something to do with the elbows of the escalator... Consider this, the diameter of the hand rail is a good metre or more wider then the stairs them selves right? Now, rotating two rings of different diameters in unison is no problem but the stairs are not perfect rings, they are VERY exaggerated ovals, with a pretty severe kink on each end. So, visualise (looking from the bottom) what happens when the escalator bends up and bends back down at the top. When you get on at the bottom there is a flat bit where stair and hand rail parallel, then quite quickly it turns into a up sloping section. The radius of that change is much greater for the stairs then it is for the hand rail, then the two are parallel again until the top where it has to turn flat again, this time, the radius for the hand rail is much greater then for the stair. Haven't quite worked out how that directly affects the speed of the hand rail yet, but I bet it has something to do with it.. Vespine 04:30, 17 January 2007 (UTC)

You might be on to something there, on an "up" escalator (and who really needs a "down" escalator, anyway ?) I think that would cause the handrail to pull ahead of the steps at the bottom, then pull backwards relative to the steps at the top. However, since you aren't positioned perpendicular to the centerline of the steps anymore, but at perhaps a 30 degree angle "leaning forward", relative to that centerline, that might work out to be just about right. This is becoming a geometry question, perhaps I should repost on the math board ? Does anyone have the dimensions and radii of a typical escalator that I could use to do the math ? StuRat 20:19, 20 January 2007 (UTC)

, causing anyone who doesn't want to be pulled over to change their grip at both locations.

I have found it possible to ignore the differential in the velocity of the handrail versus the velocity of the stair treads, although at the terminus of the stairs I am sometimes at a 30 degree angle with respect to the accepted vertical when I hold on tenaciously to the handrail and do not change grip. Edison 06:42, 17 January 2007 (UTC)

This must be fun to watch ! StuRat 20:19, 20 January 2007 (UTC)

After years of riding those things, I think it is just a maintenance issue. There is probably no direct mechanical connection between the two, and it looks like (when they are opened up) that different motors are involved. --Zeizmic 13:04, 17 January 2007 (UTC)

Howstuffworks has this diagram which shows the handrail going around a loop that is similar in shape to the loop traveled by the steps but offset vertically. An electric motor drives the steps, and the steps drive is in turn connected to the handrail drive by a drive belt. If this drive belt broke then the handrail would stop while the steps continued to move - hence the need for a handrail speed sensor. I imagine is it difficult to synrchronise the speeds of the two drives precisely. On some escalators the motion of the handrail is noticeably uneven, which could be due to the drive belt slipping. Gandalf61 13:40, 17 January 2007 (UTC)

You mean they actually travel at differant speeds? I never noticed it! I'll see if I can next time I "go up". | AndonicO ^{Talk · Sign Here} 20:16, 17 January 2007 (UTC)

You will never ride an escalator the same way after seeing this: [1] alteripse 00:22, 19 January 2007 (UTC)

Economical Nutrition (+ side question)

I've found I need to save (for my education) a lot more than I had originally anicipated. I currently have 4600 euro and I need 12000 euro by September. I pay rent of 175 (about the cheapest I'm likely to find in this country so pretty irreducable) and 78 euro health insurance per month. If I can save 250 per week for 28 weeks (best case senario of extending my work contract which is actually due to expire in June) then I'll have an additonal 7000 euro. This leaves me a food budget of 23.57 euro per week. Could someone suggest the most economical foods in terms of nutrition (both vitamins and energy), particularly in the Netherlands?

I don't know about the Netherlands, but food in the US is usually much cheaper, and also healthier, if you buy it unprocessed. For example, you can get a big cylinder of oats (for making oatmeal), for about 1/10th the price of the premixed oatmeal in little bags with added sugar, flavorings, and assorted chemicals. I like to buy bananas and slice them up in the oatmeal to make breakfast for about US$0.50. Spaghetti is also quite cheap and the sauce can have lots of vitamins. Salads are healthy and cheap, too, just buy whichever vegetables are on sale that week. You can also make soups from potatoes and vegetables. Cheap protein is a bit harder to find, perhaps peanut butter sandwiches or tunafish sandwiches are your best bet. StuRat 03:21, 17 January 2007 (UTC)

For nutrition at low cost, you'd do well with a primarily vegetarian diet, with vegetable sources of protein (including minerals and fibre) supplemented by dairy, eggs, and perhaps fish. Pay particular attention to legumes and whole grains, focal foods in vegetarian systems such as described in Diet for a Small Planet based on the essential amino acids. Add some locally-grown or plentiful imported fresh fruit for the range of vitamins, and you've got the basics covered. Unprocessed "whole" foods will give you better nutrition at lower cost than processed (e.g. peanuts vs. peanut butter), but you'll have to take into account the need to cook, involving expenses of time, effort, fuel, and some basic equipment. For shopping, check your vicinity for farmers' markets and food co-ops that sell direct from the producer to the consumer, or markets in immigrant neighborhoods for non-native items such as hummus. You can also contact your health services provider for nutritional advice, that may include low-cost or free counseling.-- Deborahjay 15:42, 20 January 2007 (UTC)

This begins to make me look pretty pathetic but does anyone know of extra things I might be able to do (again, in the Netherlands) during spare time to earn more money? Even more tragically, my only example is the film Dancer In The Dark, where the lady get's these sewing needles that she has to put into the cardboard holders that are then hung on those racks in shops - I can do that! My current job is in these crazy rotating shifts which means I can't commit to a normal second job (it's almost like they designed it to be like that). --83.84.74.28 01:39, 17 January 2007 (UTC)

Can you sell blood or plasma there ? StuRat 03:23, 17 January 2007 (UTC)

I don't think you can. Do they pay enough in America to cover the nutritional cost of replacing it? In England you get a couple of biscuits and a cup of tea... --83.84.74.28 20:10, 22 January 2007 (UTC)

I've never been to Europe, so I can only add information I know from the U.S. Pinto beans and corn are not expensive either, and those together will give you enough protein to stay healthy. Over here, pinto beans are extremely cheap. Rice is fairly cheap too, since a large bag will go a long way. Lemons are a great source of vitamin C and not a bad flavoring for many foods, though I'm not sure how available lemons are in the Netherlands. Good luck! --Wirbelwindヴィルヴェルヴィント (talk) 03:58, 17 January 2007 (UTC)

In 1972 I was able to eat for $1 US per day, and today I believe it would be possible to eat for $3 per day. Buy groceries in bulk and cook. Dried beans, dried pasta, flour, rice, cornmeal, canola oil, fruit, much peanut butter, some canned vegetables, meat and fruit occasionally, . Edison 06:49, 17 January 2007 (UTC)

I echo Edison above; rice, beans, and whatever is on sale or 2-for-1. I don't think peanut butter is all the rage in the Netherlands though. :-) | AndonicO ^{Talk · Sign Here} 20:20, 17 January 2007 (UTC)

Three of us ate literally 40 pounds (18 kilograms) of peanut butter in one 9 month school year. Avoid buying restaurant or vending machine food or beverages if money is an issue, since groceries cost maybe 1/3 as much. Edison 16:00, 18 January 2007 (UTC)

Rather than seek yet another conventional job, you might consider cutting housing costs and living expenses by finding a situation that provides room and board in exchange for services: house- and pet-sitting, child care (perhaps with a premium for bilingual homework help), aid to an elderly or disabled shut-in. Investigate options for cooperative and shared housing. Your school may have advice for students on grants and loans, but also check your municipality's or county services to low-income residents. Good luck! -- Deborahjay 15:50, 20 January 2007 (UTC)

And you guys thought it wasn't a great idea... ;) — Kieff 15:58, 20 January 2007 (UTC)

Thanks for the advice everyone. Some suggestions will need some looking into. It's nice to know you all care :) --83.84.74.28 20:10, 22 January 2007 (UTC)

Unnatural Star Creation

Hello. This is probably a weak question, but I wanted to know if stars could possibly be formed by human means, and, if they could, if perhaps humans could use them for energy? (Read "The Last Question" a while ago and I just started thinking about it) Thanks for any comments! Robinson0120 01:40, 17 January 2007 (UTC)

Not with current technology, but there's nothing indicating that it's completely impossible. Possibly infeasible considering the required resources, but who knows? To harness the energy said future humans might use a Dyson sphere, an Alderson disk, or something similar. -- Consumed Crustacean (talk) 02:10, 17 January 2007 (UTC)

Many things we take for granted today were similarly infeasible in 1807. Edison 06:50, 17 January 2007 (UTC)

I seem to remember that Jupiter’s mass is relatively close to the point at which it could have formed a star. If you could some how increase Jupiter’s size by a little (say push Mars into it) it might very well form a star. Of course doing this would kill us all. Also, we already do use a star for energy. See Solar power. Creating a new star would serve no purpose then. I should also mention that the mass cutoff point for a star precludes one from creating a “mini-star.” S.dedalus 07:10, 17 January 2007 (UTC)

Jupiter is almost 3000 times as massive as Mars, and according to its article, it would need to be 75 times as massive as it is to become a star. So, we'd need to find something a little more massive to push Jupiter over the threshold. But if we can develop the technology to put enough mass in one place, there's no reason we can't make an artificial star. Dave6 09:16, 17 January 2007 (UTC)

In response to Dave6’s coment above. Actually according to this [2] you would only need to increase Jupiter’s mass by about 16%. Perhaps the Jupiter article should be corrected? You’re right of course that Mars still wouldn’t do it however. Hmm. . . Pushing Saturn into Jupiter might create a star however if New Scientist is to believed. S.dedalus 20:17, 17 January 2007 (UTC)

Ups, my mistake OGLE-TR-122b is only 16% larger. However it’s mass is still above the 75 Jupiter-masses. How about pushing all the gas giants in our solar system together? That might work. ;-) S.dedalus 22:45, 17 January 2007 (UTC)

The idea of turning Jupiter into a star has been explored in fiction - see 2010: Odyssey Two - although it was achieved by non-human technology. Gandalf61 10:48, 17 January 2007 (UTC)

In a manner of speaking, man creates a star every time he detonates a nuclear bomb... it's just that they're very short-lived. Vranak

The only nuclear weapons which utilize nuclear fusion, as stars do, are fusion bombs (i.e. H-Bombs). The process is similar, though I'm not sure that H-Bombs use the the proton-proton chain and the CNO cycle which occur in stars. Not to mention the size/gravity differences. -- Consumed Crustacean (talk) 17:20, 17 January 2007 (UTC)

So if Jupiter gets hit by more comets, we would live (or die) in a binary star system? Or would the sun eventually suck the "Jupiter star" into itself? | AndonicO ^{Talk · Sign Here} 21:02, 17 January 2007 (UTC)

It would take a lot more than just comets. If the lowest estimate for the minimum size of a brown dwarf is correct, you could turn Jupiter into a short-lived star by dropping Saturn into it, or maybe by adding the entire Oort cloud. --Carnildo 21:43, 17 January 2007 (UTC)

Alright, thanks. I figured there would probably be some way to do so; I might have heard about the Jupiter thing a little while ago (even though we probably wouldn't use it for the reasons stated above). Thanks for the information, all! Robinson0120 22:14, 17 January 2007 (UTC)

Believe it or not Jupiter actually makes up more then 50% of the mass in our solar system. Even if you collided the whole solar system into Jupiter (Except for the sun it self of course) you wouldn't have more then twice the mass of jupiter to begin with. Vespine 05:53, 18 January 2007 (UTC)

Sounds like an engineering nightmare. I guess we won’t be creating new stares any time soon! S.dedalus 07:50, 18 January 2007 (UTC)

Humans create stars every year when they put little no-talents into movies and promote the shows. Edison 16:01, 18 January 2007 (UTC)

It depends on exactly what your definition of a star is:) Would it help if the material was at a higher density instead of a higher mass:)Hidden secret 7 18:38, 22 January 2007 (UTC)

Physics question

Our teacher has set us a hard question this week. I know you dont do homework, but maybe you could give me some pointers. Our teachers is a bit strange in the questions he gives us ,but could you please help thanks

OK the question is: A man is standing on the top of everest and we assume the outside temperature is -30C, and there is a sheer drop down to earth from where hes standin, then if he was to urinate over the side, upto what distance would the stream remain liquid. Bertie

There is no answer to that. Too many other variables. X [Mac Davis] (DESK|How's my driving?) 02:05, 17 January 2007 (UTC)

And also he didn't specify what distance he want, the distance the urine stream travel or the height drop until it freezes, neither does he specify the pressure, the amount, the composition, the temperature and the angle of the urine stream, nor wind speed, humidity of the environment etc. etc. etc. So ask him about those variables and see what happens... :-p --antilived^{T | C | G} 03:14, 17 January 2007 (UTC)

The question is just another way of asking [1] how long does it take urine to go from body temperature to freezing in a temperature of -30C, and [2] how far would gravity take it in that time. It's the first part that's hard. If it helps, normal urine osmolality is 50 to 1400 mOsm/kg. - Nunh-huh 05:37, 17 January 2007 (UTC)

You would have to know how long it would take to freeze, assume no air/wind resitstance, and then take the time it took to freeze and the acceleration due to gravity (10m/s^2) and then its easy. Rya Min 02:28, 17 January 2007 (UTC)

I seem to recall reading that you can tell if it's -50F or below because your spit will freeze and shatter when it lands at those temps. StuRat 03:28, 17 January 2007 (UTC)

To the original poster: Is this question for marks at all? I remember my Physics teacher giving several weird questions "to chew on" overnight.--JDitto 03:44, 17 January 2007 (UTC)

Trick question. Everest is already part of the earth. And if you do the calculation of time to go from body temperature to freezing, keep in mind the freeze point is dependant on altitidue. Also keep in mind the dry adiabatic lapse rate. From the altitude of Mt. Everest and the given temperature, you can find the difference between standard temp and pressure. Calculus is your friend. --Tbeatty 06:25, 17 January 2007 (UTC)

Qualitatively, the stream would break up into droplets which would reach their Terminal velocity quickly, then it would freeze into droplets like lead in a Shot tower. There would be some Sublimation (chemistry) as they dropped from the mountain to the land below. The high speed would facilitate heat loss, but I cannot think of a straightforward calculation. Edison 06:57, 17 January 2007 (UTC)

Among all the unknowns, the most important one is the speed with which the stream or droplets loose heat to the environment. While tiny droplets will freeze almost instantly, large drops or a wide stream require more time. The stream will start to cool immediately, but will the stream start to freeze already before it would break up into droplets? How do we find out how wide the stream is? Measure it with a caliper? :) Our article Urination offers no clue. And what is the freezing point of urine? There is a formula for the freezing-point depression, but I don't immediately see how to apply it. Is this for a graduate course on Applications of Cryophysics in Mountaineering?  --Lambiam^Talk 10:25, 17 January 2007 (UTC)

Ah! I would expect this is a "chewing on" question. Maybe he (or she, I suppose) wants you to think about how to go about solving it! What variables should you need? You don't necessarily have to solve it to get a constant. Don't forget air pressure! How do we find out how wide a stream is? I know Mythbusters measured that one. Does air humidity belong in the equation? X [Mac Davis] (DESK|How's my driving?) 12:33, 17 January 2007 (UTC)

One author of a book said that, on an expedition to Greenland, he and his comrades threw up a bucket of hot water. Result: it came down as ice. I don't know how much of a differance there is between urine and water. | AndonicO ^{Talk · Sign Here} 21:07, 17 January 2007 (UTC)

I'd just work out how long it would take for 37C -> 0C in this situation, then use this number to calculate how far anything would travel in this time in freefall, and hope it doesn't get to terminal velocity. Aaadddaaammm 03:06, 19 January 2007 (UTC)

zetasizer in small sizes

Are zetasizers available in miniature size (as in microcameras so as to fix in human body for detection)? Or can they be made for research? If yes company to be approached? 02:43, 17 January 2007 (UTC)

The internet doesn't seem to know what a zetasissor is, even if you spell it zetascissor, maybe you can clarify a little? Vespine 04:17, 17 January 2007 (UTC)

" Zeta Scissor: Mas poderosa que la shotgun, ademas que es facil y rapido de usar se obtiene muchos puntos con ella mas que la Laser, si escuchastes bien mas puntos que la laser esta belleza avienta una navaja en forma de media luna y no tiene contratiempos al igual que el laser y la heavy machine gun." Did you know that ? -- DLL ^{.. T} 19:11, 17 January 2007 (UTC)

The above somewhat rendered into English by Babel fish: "Zeta Scissor: But powerful that shotgun, ademas that is facil and fast to use obtains many points with her but who the Laser, if escuchastes well but points that the laser this beauty throws a knife in form of average moon and does not have misfortunes like the laser and heavy machine gun." Clear? Edison 16:05, 18 January 2007 (UTC)

Are you thinking of particle sizing by using the zeta potential? i.e. a "zeta sizer"? There are companies that make equipment for this: here's one company based about 10 miles from where I live [3] Don't know if they make micro scaleimplantable versions... Malcolm Farmer 00:46, 19 January 2007 (UTC)

  : Thanks Malcolm,..i was actually looking for the same thing, a nano sized zetasizer, to fit it  
    inside a host...the way doctors put minicameras during surgeries.
    Please do suggest about the companies which can device it... User: Manju.setti 

hydroelectricity and fishees

I just read in this website that fish can easily swim through hydroelectric dam turbines turning at 81.8 rpms. Is this true? Those giant turbines are spinning more than once every second! --JDitto 03:38, 17 January 2007 (UTC)

Remember a fish in water is VERY different from your hand in the air. When the turbine is spinning it is displacing the water with the fish IN the water. As the water gets pushed through/by the turbine, the fish is IN that water and would get pushed out with it, I'm sure a dolphin or shark might get messed up, but a regular fish would be small enough just to get pushed out with the water. I don't think it's unreasonable. Vespine 04:13, 17 January 2007 (UTC)

Hydroturbines do kill fish, even small ones[4]. There is active development of new turbine designs to reduce fish mortality[5]. --Duk 06:38, 17 January 2007 (UTC)

I have seen large fish chopped in pieces by such a turbine. I expect small (or lucky) fish come out slightly perturbed (and a bit let down) after their adventure through the turbine. Edison 07:00, 17 January 2007 (UTC)

What I hear from friends who do salmon passage (through large dams) studies on the Columbia River is the principle danger is the dramatic changes in pressure rather than the turbines. It may be different for smaller hydroplants. --TeaDrinker 08:24, 17 January 2007 (UTC)

Change in pressure? So the pressure inside gets so strong that it crushes the fish inside? --JDitto 05:15, 18 January 2007 (UTC)

Remember, the liquid passing through a hydro dam's generator can't change in volume (much), so if we're to extract any energy from the liquid, it must be through a reduction in pressure. The liquid's pressure is very high going into the turbine and much lower exiting the turbine; the fish have a tough time accommodating to this very sudden change.

Atlant 14:58, 18 January 2007 (UTC)

pixel counter

Is there any software (hopefully free) that can calculate the number of pixels in an image of a certain color? --hello, i'm a member | talk to me! 04:37, 17 January 2007 (UTC)

In some image formats, that will be difficult because the exact color of each pixel is not stored in the file. So, it may change from one renderer to another. Also, what do you mean by "a certain color"? If two pixels are off by 1/256th of a shade of red, are they the same color? Our human eyes would probably say so, but a computer would say they are different. --Kainaw ^(talk) 07:59, 17 January 2007 (UTC)

You asked this question somewhere else, yes? And you were given a number of answers... --24.147.86.187 15:21, 17 January 2007 (UTC)

sea snake reproduction?

how do sea snakes reproduce? Do they have to return to dry land to lay eggs, or are they live bearing? --Krsont 05:15, 17 January 2007 (UTC)

• It depends, apparently. Some give birth to live young (ovoviviparous), while others are egg-laying (oviparous), and thus must return to land. See Elapidae for details. -- MarcoTolo 05:20, 17 January 2007 (UTC)

Heartbeat sounds

Is it common for any person to feel or hear their pulse from the scalp or the head when healthy.--Biggie 08:18, 17 January 2007 (UTC)

Well, it's not possible to hear your pulse from any external part of the body. It is also not common to be able to "feel" your pulse anywhere normally, except perhaps in your neck during high-intensity physical activity, or in your eardrums. BenC7 11:48, 17 January 2007 (UTC)

Just yesterday I could feel it and hear it... and see it! However I personally attribute this to me having erratic blood pressure. My intraocular pressure is quite feelable, phosphenes are generated on the heartbeat, and I can feel the heartbeat in my eyes. I could also hear it pulsing in my ear. I'm perfectly healthy, as far as my doctor and I know. Except for maybe that. Hope I don't die. X [Mac Davis] (DESK|How's my driving?) 12:29, 17 January 2007 (UTC)

All right Thank you very much for the info--Biggie 20:05, 17 January 2007 (UTC)

This question asks for medical advice. The Reference Desk cannot offer competent professional advice on questions of this kind. If you have concerns about a potentially serious medical problem, please immediately contact a qualified medical professional.

No, this question does not ask for medical advice. It asks for medical information. They are not the same. - Nunh-huh 03:26, 18 January 2007 (UTC)

I can also hear my heart beating sometimes, and see it &c:) I think I am healthy, but my blood pressure is a bit odd and I can usually only hear it when I have just walked up lots of stairs  :( And I can feel it in the sides of my head:( I think this is normal, but I have never been anyone else, so I wouldn't know:]Hidden secret 7 19:19, 18 January 2007 (UTC)

I can hear my heartbeat often at night when lying in bed with my ear against my pillow. I'd say it's pretty normal ("normal" being a very broad range) --Psud 12:06, 25 January 2007 (UTC)

50/60 Hz Microwave oven

Can a microwave oven designed for 60HZ WORK PERFECTLY IN 50HZ SUPPLY ,IF VOLTAGE IS TAKEN CARE OF ? Will its performance & life be affected ?

Pranav samel

From my experience, electric appliances built for 60Hz work fine with 50Hz electricity, except they run a little slower. The exception is electric clocks built for use in the U.S. because they base their time on the 60Hz rate and thus only go 5/6 as fast when plugged into a 50Hz socket. howcheng {chat} 17:12, 17 January 2007 (UTC)

Doubtful. Unless the transformer in the microwave is designed to handle the lower frequency, the slower cycle will cause the core to saturate, turning it from an inductive load to a short circuit. In layman's terms, your microwave will blow a fuse or catch fire. --Carnildo 21:49, 17 January 2007 (UTC)

Also (depending on how the AC is converted to DC in the machine), the DC voltage produced may be lower than what is required, due to the lower frequency and hence the oven may not work properly -- WikiCheng | Talk 07:47, 18 January 2007 (UTC)

Some digital clocks get their timing pulse from the source power, so it might run slow. Maybe that would compensate for the lower oven voltage. Edison 17:52, 18 January 2007 (UTC)

Late 1800 supernaturalism

"The discovery consists," he says, "in subjecting the vapors of volatile liquids to the action of concentrated sun-light, or to the concentrated beam of the electric light." The vapors of certain nitrites, iodides, and acids are subjected to the action of the light in an experimental tube, lying horizontally, and so arranged that the axis of the tube and that of the parallel beams issuing from the lamp are coincident. The vapors form clouds of gorgeous tints, and arrange themselves into the shapes of vases, of bottles and cones, in nests of six or more; of shells, of tulips, roses, sunflowers, leaves, and of involved scrolls. "In one case," he tells us, "the cloud-bud grew rapidly into a serpent's head; a mouth was formed, and from the cloud, a cord of cloud resembling a tongue was discharged." Finally, to cap the climax of marvels, "once it positively assumed the form of a fish, with eyes, gills, and feelers. The twoness of the animal form was displayed throughout, and no disk, coil, or speck existed on one side that did not exist on the other." Professor Tyndall

Is this possible, and what if any would be the practical application thereof? Thank you81.144.161.223 11:55, 17 January 2007 (UTC)

Does this refer to the Tyndall effect? [[John Tyndall] was a sucessor to Michael Faraday as leading scientist of the Royal Society. He was a careful observer, and a famous debunker (spontaneous generation). Please provide the source for your quote so it can be better evaluated. I find the "spiritualist" H. Blavatsky (p127)attributes that quote to Tyndall, in Blavatsky's book "Isis Unveiled" [6], which contains what appears to be a lot of nonsense. It is hard to believe Tyndall was tripping like that unless he found some "magic mushrooms." Maybe the vapors of the heated metals had affected his brain. Blavatsky does not say where in Tyndall's writings he found the quote. The first edition of Blavatsky was 1877, and he says Tyndall's discovery was "not so long ago," so that is a clue to look in the 1870's.Edison 18:12, 18 January 2007 (UTC)

Non-circular pupil

In an optical system what would be the effects of a non-circular pupil? How will the bokeh be changed? What would it be like to see through a sheep's eye? --antilived^{T | C | G} 11:58, 17 January 2007 (UTC)

The pupil shape affects resolution properties as well as the bokeh (the shape of the blur from an out-of-focus point source). The bokeh will in general look like an image of the pupil. The pupil of a typical camera is in fact subtly non-circular due to the finite number of blades in the aperture iris. If you look carefully at an image with an isolated out-of-focus point source, you may be able to see that it looks slightly polygonal, in the same way that the lens reflections seen when sunlight hit the lens do (these are also images of the pupil). If your pupil is oval or slit-like, let's say tall and narrow, then the resolution (the sharpness of the in-focus image) will be different in the horizontal and vertical directions. If your lens is good (or your aperture small), so that the resolution is limited by diffraction, then vertical resolution will be better than horizontal. If the lens is less good, so that resolution is limited by lens aberrations rather than diffraction, then the opposite situation might occur, with horizontal resolution being better than vertical. If you want to know what the world looks like through a long, narrow pupil, just squint! (Or, better, cut a very narrow slit in a piece of paper and hold it in front of your eye - that way your eyelashes won't complicate matters.) --mglg_(talk) 17:27, 17 January 2007 (UTC)

A look at our article on astigmatism may also be of interest to you. Grutness...wha? 07:17, 18 January 2007 (UTC)

You can actually see the effect if you look at a "'scope" (Cinemascope or Panavision) film. In that case, the "pupil" is still circular, but the optical system compresses things from side-to-side. The result is that out-of focus lights appear as vertical elipses rather than circles.

Atlant 15:02, 18 January 2007 (UTC)

How will the amount of light be changed? eg. If an oval pupil that's f/5.6 vertically and f/2.8 horizontally what will happen on the image plane? Thanks. --antilived^{T | C | G} 23:21, 18 January 2007 (UTC)

The amount of light transmitted is proportional to the pupil's area, which for an elliptical pupil is proportional to the product of its long and short diameters. An (f/5.6)x(f/2.8) elliptical pupil will transmit twice as much light as a circular f/5.6 pupil, but half as much as a circular f/2.8 pupil. In other words, the same amount as a circular f/4 pupil. -- 169.230.94.21 23:12, 22 January 2007 (UTC)

Autoclaves

Hi

I have been trying to find out some basic information about non-medical autoclaves, for example those used in laminate glass screen technology, areospace industries, formula 1 racing, etc. I want to know the following:

What is an autoclave? How do they work? What are their main uses outside of sterilisation? How is high pressure air or gas used within the process?

I have searched all the usual places on the web and done general searches through Google, but can't find anything general enough. Wikipedia (which, by the way, I think is great!) only really talks about medical autoclaves.

Any information you could provide would be gratefully received!

Thanks KiwiTS 12:46, 17 January 2007 (UTC) KiwiTS

See the article autoclave for more information. An autoclave is basically just an oven. The autoclave heats up, usually to about 121°C, which kills all the bacteria in the chamber (and in any objects which might be in that chamber) with heat sterilization. However, heat alone in a dry environment doesn't penetrate living tissue very well (a good example of this is the sauna, which can reach temperatures above the boiling point of water, and yet are considered a fine place to have a quick rest), and so steam is added to the equation to better conduct that heat into anything put in the chamber (a steam room as hot as a sauna would rapidly kill a human). However, there is another glitch, what if you want to sterilize water or an aqueous solution? This is where pressure comes in. The chamber is also pressurized so that even at 121 degrees, it won't boil and evaporate/boil over and make a mess. As for "What are their main uses outside of sterilisation?", I suppose they could be used for heat-assisted lamination of water-containing things...? To be honest, I can't think of anything other than sterilization that would be easier and cheaper to do in an autoclave than by some other method. Tuckerekcut 16:24, 17 January 2007 (UTC)

Here we go: Aerated autoclaved concrete. Tuckerekcut 16:25, 17 January 2007 (UTC)

I should point out in case it wasn't obvious from what tuckerercut said that autoclaves are used for sterilisation in many circumstances not just medical. Biologists doing research use autoclaves all the time for example Nil Einne 16:41, 18 January 2007 (UTC)

There are many industrial uses of autoclaves. For sterilising medical goods/ supplies an autoclave using ethylene oxide can be used. Years ago I worked in the rubber goods industry, where rubber products were cured in a steam autoclave. I suspect this also used the steam pressure to reduce the volume of any air pockets and improve adhesion of the component materials of the rubber items. A modern use of an autoclave is to produce composite material assemblies such as aircraft tailplanes and other structures. Many modern aircraft use composite assemblies to reduce weight/ improve performance. Think of an autoclave as a very large pressure cooker like you would see in a kitchen. The heat and pressure act to speed chemical linking of molecules into a final, more useful form. A mild form of this is used to cure acrylic resin used in creating dental bridges and dentures :) (207.188.64.234 16:22, 31 January 2007 (UTC))

the free website for science

hi guys i wonder is there any free website for learning science like chemistry, physics, and biology for those who didnt heard of it.thanks 14chung 12:48, 17 January 2007 (UTC)

my grade is 7th grade in singapore and i need basics... wikipedia is hard to understand thanks14chung 15:48, 17 January 2007 (UTC)

Err...wikipedia? If it's a structured course you need, try the courses at wikiversity, they're grrrrrrrreat. yandman 13:02, 17 January 2007 (UTC)

'they're grrrrrrrreat' - I love it; maybe they should adopt a new slogan Wikiversity: As supported by Tony the Tiger! --Neo 13:31, 17 January 2007 (UTC)

Depending on your level you could use anything from enchantedlearning.com to MIT OCW. Could you give us information to help us, such as grade in school? X [Mac Davis] (DESK|How's my driving?) 14:03, 17 January 2007 (UTC)

You can try this and this for a start. -- WikiCheng | Talk 14:09, 17 January 2007 (UTC)

Those are both excellent sites. X [Mac Davis] (DESK|How's my driving?) 14:24, 17 January 2007 (UTC)

Old Age in fish

Why,in the evolutionary sense, do certain fish reach senescense? What possible genetic advantage is there to surviving beyond breeding age? The only possibilty I can come up with is that these pensioners become selectively cannibalistic. That is, they then eat or kill offspring of thier genetic rivals. I know in some amphibian species, cannabalistic individuals DO, somehow distinguish between thier siblings and others. Is that what we believe these olds timers are upto?216.209.138.128 13:01, 17 January 2007 (UTC)

You know, not every phenomenon in the natural world needs to be closely explained by genetic theory. It's a rather narrow view to look at the whole wide world as being nothing more than a medium for gene propagation. Vranak

Well, you know, calling that view narrow is a bit narrow it self in my opinion, gene propagation is after all why the living world exists the way it does. Thinking somehow that this view de values or cheapens life is what I would call narrow. Everything has a reason, even if it is not obvious or intuitive, nothing happens without a reason. That doesn't mean that life isn't ammazing and wonderful! The way I would approach the above question is to turn it around and instead say "What possible genetic advantage is there to dying once beyond breeding age"?? Many fish survive in shoals, they get hunted by relentless predators their whole life and the only way the species survives is by sheer number of individuals. Having a life span past just the breeding age means that if there are any individuals that are lucky enough to survive past breeding age they pad out the numbers. Further, if an old non breeding fish gets eaten, then a young a breeding fish has been spared and the shoal has a greater survivability. Vespine 21:41, 17 January 2007 (UTC)

My narrow view has evolved out of years of trying to pigeon-hole every behaviour as either gene or meme propogation. At a certain point you begin to realize that such a simplified view of life is more a product of human vanity, thinking we can know everything, than actual correspondence to the real world.

Anyway, you left out one thing: an animal can help propogate its genes by dying, in order free up limited resources for its offspring and relatives. Vranak

back on topic: *do* fish actually survive past breeding age, as assumed by the question asker? I would have thought they continue breeding every year until they die. Even in humans, getting so old that you can't have children anymore is probably a very recent phenomenon; "wild" huntergathers rarely live(d) past 40. --Krsont 16:05, 19 January 2007 (UTC)

ecosystems

the way the human population is made up of different races.....

is a walrus in the same category(UTC)(how do i say it...isit population or community or what??)as the seals??? --203.124.2.17 13:19, 17 January 2007 (UTC) is this info i found on the net correct?? [[7]]

How to read a taxoboxEarless Seals
Grey seal
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Carnivora Suborder: Pinnipedia Family: Phocidae

Walrus
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Carnivora
Suborder:	Caniformia
Superfamily:	Pinnipedia
Family:	Odobenidae Allen, 1880
Genus:	Odobenus

Wikipedia is a helpful guide to many things, this included. If you'll look to your right you'll see two information boxes found at the earless seal (true seal) and walrus articles respectively. Under the part that says "scientific classification" is what we want to look at. Biologists try and fit every plant and animal and even bacteria, and sometimes virus into these categories. You can see that both of these animals fall under the Kingdom: Animalia, which means they are animals. Phylum: Chordata means that both of these animals have a backbone. Class: Mammalia means both of these animals are mammals. Order: Carnivora means that both of these animals eat meat and not plants. The next word says "Pinnipedia" and that is where they stop being the same. Being in the same family or order means that the animals are fairly closely related. X [Mac Davis] (DESK|How's my driving?) 14:13, 17 January 2007 (UTC)

... but they are not the same species, so they are not as closely related as the different races of humans. The biological relationship between walruses and seals is more like that between humans and chipanzees. Gandalf61 14:25, 17 January 2007 (UTC)

Actually, they belong to different families, not just different species, whereas chimpanzees and humans belong to the same family Hominidae. The relationship between true seals and walruses is more like that between humans and monkeys. -- mglg_(talk) 17:45, 17 January 2007 (UTC)

In an ecological context, populations consist of members of the same species in the same general area, while communities consist of interacting or potentially interacting populations of different species. Walruses in some area will make up a population. The walruses and seals in an area will be members of a community. Guettarda 22:10, 17 January 2007 (UTC)

If you're looking for an analog with human races, perhaps a color phase might be the closest. A subspecies is a bit more of a difference than human races, I think. StuRat 06:40, 18 January 2007 (UTC)

Humans we tend to think that everything in nature has to have a reason, but maybe not. Species aren’t finished products. To use an analogy if a Martian came from space and saw a car he or she would ask what are the exhaust are gases for. Or why does a computer give of heat.

Not Injecting coffee

Why we cannot inject cafeine on the vein? Would it kill us?.Mr.K. 14:30, 17 January 2007 (UTC)

From Caffeine:

An acute overdose of caffeine, usually in excess of 400 milligrams (more than 3-4 cups of brewed coffee), can result in a state of central nervous system overstimulation called caffeine intoxication. Some people seeking caffeine intoxication resort to insuffilation (snorting) of caffeine powder, usually finely crushed caffeine tablets. This induces a faster more intense reaction. The symptoms of caffeine intoxication may include restlessness, nervousness, excitement, insomnia, flushing of the face, increased urination, gastrointestinal disturbance, muscle twitching, a rambling flow of thought and speech, irregular or rapid heart beat, and psychomotor agitation. In cases of much larger overdoses mania, depression, lapses in judgment, disorientation, loss of social inhibition, delusions, hallucinations, psychosis, rhabdomyolysis, and death may occur.

In cases of extreme overdose, death can result. The median lethal dose (LD₅₀) of caffeine is 192 milligrams per kilogram in rats. The LD₅₀ of caffeine in humans is dependent on weight and individual sensitivity and estimated to be about 150 to 200 milligrams per kilogram of body mass, roughly 80 to 100 cups of coffee for an average adult taken within a limited timeframe that is dependent on half-life. Though achieving lethal dose with caffeine would be exceptionally difficult with regular coffee, there have been reported deaths from overdosing on caffeine pills, with serious symptoms of overdose requiring hospitalization occurring from as little as 2 grams of caffeine.

Treatment of severe caffeine intoxication is generally supportive, providing treatment of the immediate symptoms, but if the patient has very high serum levels of caffeine then peritoneal dialysis, hemodialysis, or hemofiltration may be required.

LD₅₀ would be, by the way the concentration at which a toxin kills 50% of a population. I'm not sure he's asking for "medical advice." He's asking a question about something medically-related. X [Mac Davis] (DESK|How's my driving?) 14:54, 17 January 2007 (UTC)

"Can I inject myself..." is a question that the reference desks will not answer. Hipocrite - «Talk» 14:57, 17 January 2007 (UTC)

Well good, because I didn't answer it! X [Mac Davis] (DESK|How's my driving?) 15:01, 17 January 2007 (UTC)

Ok, I have reformulated the question. Again: I am not trying to do it. I just want to know why some drugs can be taken in tea, injected, and so on, and others cannot.Mr.K. 15:46, 17 January 2007 (UTC)

If your question asks us if something will kill you, our answer will be "it might, talk to a doctor." If you would like to know about drug delivery you should read the article on it, the sources it references, and come back with a more specific question. Hipocrite - «Talk» 15:47, 17 January 2007 (UTC)

Caffeine can be and is injected into veins. As a medication, caffeine is used intravenously in newborn infants to stimulate breathing. It is safe and well-tolerated. There are no indications for intravenous caffeine outside of the newborn period that I know of. If there were a reason to do it medically, it could certainly be done. InvictaHOG 17:34, 17 January 2007 (UTC)

ThanksMr.K. 18:20, 17 January 2007 (UTC)

This is not accurate. The injectible medication referred to is Caffeine citrate. Hipocrite - «Talk» 20:19, 17 January 2007 (UTC)

Thanks for that too Hipocrite.

Only in the sense that "crack" is not cocaine. It is caffeine and it is injected, so I think it satisfies the initial question. InvictaHOG 13:48, 18 January 2007 (UTC)

Weather

The weather info on Weather.com and NOAA is very different. Why?129.112.109.252 19:49, 17 January 2007 (UTC)

Weather forecasting isn't an exact science, different groups can come to different conclusions about what they think the weather will be like. That article has a lot of information. Vespine 21:17, 17 January 2007 (UTC)

eel

What types of eel are safe to ingest, as opposed to those that are toxic and therefore not safe to ingest?

From the article: Freshwater eels (unagi) and marine eels (Conger eel, anago) are commonly used in Japanese cuisine. Unadon is a very popular but rather expensive food. Eels are used in Cantonese and Shanghai cuisine too. The European eel and other freshwater eels are eaten in Europe, the United States, and other places around the world. A traditional East London food is jellied eels. The Basque delicacy angulas consists of deep-fried elvers.[8]. Eel blood is toxic. The toxic protein it contains is destroyed by cooking. The toxin derived from eel blood serum was used by Charles Robert Richet in his Nobel winning research which discovered anaphylaxis (by injecting it into dogs and observing the effect). X [Mac Davis] (DESK|How's my driving?) 22:23, 17 January 2007 (UTC)

Here in South Africa we eat Kingklip. Sandman30s 13:53, 18 January 2007 (UTC)

Not really an eel, there's the hagfish. Its skin is used to make "eel skin" wallets, and hagfish are eaten in Korea. --125.189.164.34 15:54, 18 January 2007 (UTC)

Unidentified Sea Creature

Anyone have an idea what this is? They kind of look like very small pippies, they were found on the beach and are 3-4mm long. I have no idea what they are attached to, it kind of looks like plastic, but could be biological (calcium carbonate?). I posted this on WT:TOL, but got no response. Thanks. --liquidGhoul 06:17, 16 January 2007 (UTC)

I can't get the image to load, but my internet has been playing up, is it just me?Vespine 22:59, 17 January 2007 (UTC)

Looks like a group of young bivalves growing on a piece of plastic tubing to me. --Kurt Shaped Box 23:49, 17 January 2007 (UTC)

That's exactly what it looks like to me. X [Mac Davis] (DESK|How's my driving?) 00:15, 18 January 2007 (UTC)

Thanks guys. --liquidGhoul 01:42, 18 January 2007 (UTC)

Sex demarkation in llamas?

What are all the differences between adult male and female llamas (or mammals in general)? What are the most obvious differences besides of course the genitals?--Sonjaaa 23:01, 17 January 2007 (UTC)

This source implies there is little or no sexual dimorphism. X [Mac Davis] (DESK|How's my driving?) 00:17, 18 January 2007 (UTC)

Thanks!!--Sonjaaa 15:00, 19 January 2007 (UTC)

Carnivorous bird species as housepets?

Just been thinking about this now - people have been keeping carnivorous mammals, reptiles and fish as pets for a long time. Why is it that very few people keep pet carnivorous birds? --Kurt Shaped Box 23:46, 17 January 2007 (UTC)

See Falconry. --Zeizmic 23:51, 17 January 2007 (UTC)

I was meaning 'pet' in the more conventional sense - i.e. keeping as a companion animal in one's own home. I know that a few people keep owls and vultures in this way but it's far from common. --Kurt Shaped Box 23:54, 17 January 2007 (UTC)

Owls and penguins are the only carnivorous birds I've seen kept as pets in the sense of purely companion pets and not working pets. Owls are very messy and make a lot of noise at night. Penguins are illegal to be kept as pets in most places - but it happens. I feel that the carnivorous bird's need to hunt makes it hard to keep them satisfied as pets - which is why falcons are trained to return after hunting, not tamed into losing the need to hunt. --Kainaw ^(talk) 00:16, 18 January 2007 (UTC)

Are owls any messier or noisier than your average macaw or cockatoo? I suppose that they're not quite as entertaining or interesting-looking... --Kurt Shaped Box 01:39, 18 January 2007 (UTC)

Some owls do not make any noise, but most do. They are much messier however, their crap is full of skeletons and such, and they will also regurgitate a lot. Birds are very intelligent, and taking an intelligent carnivore from the wild, and having it not hunt, can cause lots of problems. They have extremely stong feet and sharp beaks. Cats and dogs are not nearly as intelligent as large birds. When I was young, we cared for an injured kestral, and it was not fun finding food for it. We eventually fed it lamb chops, but for a long time, we were out catching large grasshoppers for it to eat. If we had it for a long time, there would be a need for a supplement, as their prey is extremely varied in the wild, and feeding it one thing would result in deficiencies. --liquidGhoul 01:48, 18 January 2007 (UTC)

Carnivorous pets like dogs and cats were of course domesticated thousands of years ago, in fact dogs are thought to be the very first domesticated animal. I suppose no one thought it was worth domesticating a carnivorous bird, or maybe they tried and couldn't benefit enough to make it worth their wile? I guess it is interesting why there are no examples at all.. Vespine 02:07, 18 January 2007 (UTC)

Yeah, I'd have thought that it might be useful to keep a raptor around for ratting and mousing (maybe before domestic cats became ubiquitous). --Kurt Shaped Box 08:01, 18 January 2007 (UTC)

I feel that cats do work well. I live near the water. If I walk along the marsh, there are plenty of mice and bunnies (we call them alligator food). I never see a mouse or bunny near my house. I believe it is because there are two cats that my neighbor feeds (I chucked rocks at them until they learned to stay away from me). In fact, I rarely see a squirrel either - but I attribute that to the excessive number of blue jays and cardinals that wage gang warfare in my backyard all summer long. --Kainaw ^(talk) 08:06, 18 January 2007 (UTC)

'Gravity' increase if earth stopped spinning

On the earth we are pulled down by gravity, but since the earth revolves then particularly at the equator we are at the same time pulled up by.....forgotten the name of the force. If the earth stopped spinning, then how much would the net 'gravity' increase by?

Depends of your latitude. People at the equator would feel a greater change than people at the poles (who would feel nothing different). See acceleration due to gravity for more explicit info on this question. — Kieff 00:07, 18 January 2007 (UTC)

Didn't we have this question a week or two ago? Anyway, the centrifugal force produces an acceleration of v²/r, which at the equator works out to about 1/300 of the acceleration due to gravity. In other words, people at the equator would weigh roughly 0.3% more. --Anonymous, January 18, 2007, 00:16 (UTC).

Of course, we shouldn't forget that the Earth – like just about any other rotating astronomical body of appreciable size – has an equatorial bulge. Because the Earth is spinning, it has been stretched about its middle from a perfect sphere into an oblate spheroid. Consequently, the Earth's surface is about 21 km further from the Earth's centre when measured at the equator versus at the poles.

That article contains a useful discussion (see equatorial bulge#Differences in gravitational acceleration) of the relative sizes of those two factors (oblateness and accleration caused by rotation) and their contribution to a lower apparent force of gravity at the equator. The question is, if the earth stopped spinning, would its shape relax back to a (nearly) perfect sphere? If so, then you'd also need to take that contraction into account. TenOfAllTrades(talk) 02:25, 18 January 2007 (UTC)

Probably, but I think that'd take quite a long while. It's a lot of mass to be rearranged. — Kieff 02:32, 18 January 2007 (UTC)

Except in the case of oceans, where the water could be rearranged quite quickly, with a great deal of sloshing in the process. Since the oceans aren't 21 km deep anywhere, I imagine the oceans would completely move from the equator and a good deal of the tropical zone, and slosh towards the poles, where the water might become several kilometers deeper, completely submerging Antarctica. This makes for some interesting speculation. StuRat 05:23, 18 January 2007 (UTC)

That'd make a good storyline (excuse?) for a Hollywood special effects movie. Just add a few intrepid scientists, military men and nerds trying to prevent a disaster as huge tidal waves threaten to swamp all the world's coastal zones as the earth gradually stops spinning (due to an asteroid strike at the beginning?)... --Kurt Shaped Box 06:36, 18 January 2007 (UTC)

More to the point, the atmosphere would do the same. The ex-equatorial landmasses (indeed, the whole of the tropics) would be left poking out into space. –EdC 14:31, 18 January 2007 (UTC)

I think that for any mass such as the earth, if it stopped rotating but remained the same shape (which it would not; it would fly apart if stopped suddenly, and if it had never rotated it would be more of a sphere and have no equatorial bulge) the gravity does not change if it is rotating or stationary. The weight will change, but that is because of the elimination of centrifugal force. The equation for gravitational attraction does not include a rotational term, just the gravitational constant, the distance, and the masses. The weight is a superposition of gravitational attraction less centrifugal force. Edison 16:39, 18 January 2007 (UTC)

The local apparent gravity is in fact dependent on the rotation of the earth; you have the actual gravity which is always radial, and then you have the centrifugal acceleration which is always directed directly away from the earth's axis. (On the equator, this is straight up; at the poles it's due south/north, horizontal, and nearly 0 in magnitude; elsewhere it's toward the equator and pitched up by your colatitude.) This means that "down" is not only weakened but redirected; it doesn't point at the center of the earth. As such, if you stop the Earth rotating (somehow, and gradually) you change which direction is considered down and thus which things are level. In short, the entire temperate zones would take on a slope toward the poles, and it is this effect which would drive the de-oceaning and de-airing of the tropics. Of course, there is still some air at 21km altitude, and I don't know how fast the crust (riding on semi-liquid mantle as it is) would react compared to the air and water, but the effect could be real. --Tardis 04:11, 20 January 2007 (UTC)

January 18

Energy and Radiation

If a hydrogen bomb where to be set off in a tube that could magnetically confine the blast and exit it out behind the tube all except of course the neutrons then how much energy would be needed. Second how much shielding would I need to trap most of the escaping neutrons?67.125.158.217 01:12, 18 January 2007 (UTC)

Note that while a magnetic field will (or can) contain charged particles, it won't stop neutral particles (mostly neutrons) or electromagnetic radiation. In other words, all the gamma rays, x-rays, ultraviolet radiation, visible light, infrared energy, etc. will still come spilling out. This link suggests that for a moderately-sized nuclear weapon detonated in the lower atmosphere, some 35% of the total energy yield of the nuke will show up as heat, light, and soft x-rays; another 5% of the energy will be in the form of hard gamma rays and energetic neutrons. TenOfAllTrades(talk) 02:34, 18 January 2007 (UTC)

Taking that energy and putting it into some kind of shielding,

• for a 100 kiloton bomb;
• there will be 40 kilotons of heat and radiation;
• which is about 1.5·10¹⁴ J;

Which is enough energy to vapourize about 150 tons of lead. Your shielding is going to need to be really durable.... TenOfAllTrades(talk) 02:41, 18 January 2007 (UTC)

So with current materials how durable can I get?

Are you implying you're actually going to set off a hydrogen bomb in a tube? --Wooty Woot? contribs 06:07, 18 January 2007 (UTC)

Make the walls of the tube really, really thick and hope that the thing doesn't shatter under pressure? Ought to make an interesting Youtube video, however it turned out though. --Kurt Shaped Box 06:43, 18 January 2007 (UTC)

It would be more popular if it did blow up. ;-) On a more serious note, this would be a good question for mythbusters, if it wasn't a nuke we're talking about. | AndonicO ^{Talk · Sign Here} 12:13, 18 January 2007 (UTC)

I've always thought this was one of the more-clever jokes in Mars Attacks! -- you know, the scene where the Martian captures the H-bomb inside his gadget, breaths in the result, and then speaks in a very high-piched helium voice Ack. Ack ack ack, ack!. I've always wondered how many people "got" the joke?

Atlant 15:10, 18 January 2007 (UTC)

Escape Velocity

If a craft was launched from the surface of the earth at escape velocity and could travel through the air without burning up how could someone ensure that the travellers inside the craft would not get crushed?

The Escape velocity article states it is a little over 10km/s, (that's 10 thousand meters a second) a human finds acceleration over 3g uncomfortable, that's 30m a second per second, manned rockets are usually limited to that acceleration. Fighter pilots can experience up to 10g for brief periods. Colonel John Paul Stapp survived 46g (still only roughly 460m/s per second) but that's commonly considered fatal in all but minute doses/periods of time. Even at that rate you would need more then 20 seconds and 5km to reach speed. Acceleration is acceleration, you can't negate the force except by slowing down the acceleration. You could make it more then 3g if the occupants were unconscious and maybe suspended in some sort of viscous fluid. What if you had a slingshot type device which accelerated them along the ground first for a while then curved up, only releasing them then at sufficient velocity, that would be more likely to leave the occupants intact. Vespine 02:36, 18 January 2007 (UTC)

Vespine, your previous argument still applies to the centripetal acceleration at the curved part of your slingshot device. The centripetal acceleration will actually exceed its own vertical component, so the situation is not improved. Thus the slingshot device would need to be even taller than the 5km you calculated above, under the same assumptions. --mglg_(talk) 02:45, 18 January 2007 (UTC)

Actually, if air resistance really is ignored, then we don't need to curve up. Just launch the thing horizontally in an obstacle-free direction such as out over the ocean. You still need a multi-km acceleration path, but a horizontal one is less absurd. In reality, air resistance would kill that approach because of the very long time it would take to get out of the atmosphere. --mglg_(talk) 02:54, 18 January 2007 (UTC)

Keep in mind that "escape velocity" is really a very artificial measure; one never needs to attain earth's escape velocity to escape the earth's pull. What you really need is to produce earth's escape energy. 100 miles above the surface the effective "escape velocity" is much lower. So just take your time escaping gravity, and avoid getting crushed :) --bmk

Since this is a theoretical gadget, I would place the passengers in a very very long tube with a viscous damping mechanism, such that the whole assembly was accelerated to escape velocity quickly, but the passengers accelerate more slowly to limit their acceleration to a survivable one of, say, 10 G. From Escape velocity: "On the surface of the Earth, the escape velocity is about 11.2 kilometres per second." (This is 25,000 miles/hour, compared to typical orbital velocity of 17000 mph for a 150 mile altitude.) To go from 0 to 11,200m/s in 1 second would be 1143 G for the total apparatus, from (11200meters/sec)/(9.8 meters/sec). The tube would have to be long enough that the passengers accelerated 1/114 as much as the tube. Like I said, a very, very long theoretical tube. If the launch was 10 seconds for the vessel to reach escape velocity, then it would experience 114 G and the passengers would have to experience about 1/11 as much acceleration, somewhat more plausible. If 114 seconds of launch were allowed, then the passengers would experience 10 G without any special doodads other than a well cushioned seat and perhaps an inflatable suit such as fliers wear for high G maneuvers. Realistically, rocket scientists have claimed that the Jules Verne "Moon gun" projectile, emerging from the barrel at escape velocity, beside squashing the passengers to pulp, would hit such dense air it would lose velocity and fall to the ground. So it is necessary for a ballistic projectile hurled into space to reach its final velocity up where the air is thin. Sci-fi writer long ago speculated about a mass driver built on Mt. Everest, so the projectile would leav it at high speed at 29,000 feet. Is the air there thin enough it could continue into space and retain escape velocity when it left the atmosphere? NASA rockets save their highest acceleration until they are at extreme altitude so they do less work pushing through dense air. Since we are building only theoretical launchers, I could also have a huge dense mass in front of the passengers, whose attraction cancelled the g force due to acceleration. Then the overall apparatus could go from 0 to 11,200 meters/second in .01 seconds, as if fired from a cannon. The G force on the total apparatus would be 1,120,000G. The G force on the passenger would average 0. (Not responsible for any tidal forces which are greater on the passenger's nose than on the back of his head tending to pull him asunder.) The apparatus would work best with flat passengers (the problem did not specify human passengers). Not responsible for any destruction to the Earth from the equal and opposite reaction. Edison 17:15, 18 January 2007 (UTC)

Apollo 11

My little brother is doing some book report on Neil Armstrong, and he claims that the Apollo 11 mission planned a spacewalk (not a moonwalk). My mom also claimed that the video of Neil Armstrong climbing down the ladder is a fake, because there were no cameras that they could use to even record video outside the lander until Armstrong reached the surface. Is there a grain of truth in either of these statements? -- AMP'd 02:14, 18 January 2007 (UTC)

Nope. The Apollo Lunar Module was designed with television in mind, and had a camera mounted on the exterior of the descent stage to capture Armstrong's steps. Our article on the Apollo TV cameras has lots of detail; the camera you're interested in is the first one listed in that article.

Your mother is correct in one regard. Neil Armstrong is NOT the person you see in the famous shot of the man getting off the lunar landing. Often that clip is combined with the audio of Armstrong saying "One small step..." quote. However, the person in the Lunar landing shot is the 2nd astronaut Buzz Aldrin. Aldrin talks at length about the journey in his book (which I highly recommend.) Armstrong had walked across the moon and captured the moment that Aldrin descended. Jeff Carr 03:23, 20 January 2007 (UTC)

The name of the book I was thinking of is "Men from Earth". I had to look it up as it's not on his wikipedia page. Jeff Carr 03:28, 20 January 2007 (UTC)

See also Apollo moon landing hoax for more details about – and explanations for – various 'errors' made by NASA in faking the moon landing. TenOfAllTrades(talk) 02:48, 18 January 2007 (UTC)

Awesome! Now to prove my mom wrong. -- AMP'd 03:17, 18 January 2007 (UTC)

If she's still not convinced, the website [9] has very deeply researched refutations of all the usual hoax claims. Maelin (Talk | Contribs) 04:50, 18 January 2007 (UTC)

Also note that if no cameras were yet set up outside the capsule, they would only need to go out and set them up, then repeat the "first steps" 15 minutes later for the cameras. I suppose this is "fake", in a sense, but it doesn't make much difference to me. StuRat 03:50, 18 January 2007 (UTC)

Note that many famous historic photos are actually ":staged" in this way - most famously, the Iwo Jima flag-raising during WWII. Grutness...wha? 07:23, 18 January 2007 (UTC)

Famously, but incorrectly. The photo of the second Iwo Jima flag raising was not staged. See [10]. - Nunh-huh 07:47, 18 January 2007 (UTC)

Apollo 15, 16 and 17 included "spacewalks" (some only involved sticking head and arms out of the capsule) to retrieve experiments from the outside of the capsule during the flights to and from the moon. I don't believe that the earlier missions ever included these in their plans. Rmhermen 16:08, 18 January 2007 (UTC)

TV cameras had been used on the moon long before Apollo 11. Three unmanned Ranger craft had sent back pictures before they impacted in 1964 and 1965. Five unmanned Surveyor program craft had sent back pictures and tested the soil from 1966 through 1968. No really new or exotic technology was required, and it was very easy to have a camera already on the outside of the lunar lander to televise the first step. It was an obvious thing to put on the mission. Although Apollo 11 was not intended to and did not do a spacewalk or EVA other than walking on the moon, Apollo 11 had about everything needed to do a spacewalk. They could have put on the moon suits, exited from the LEM, and tethered themselves outside with a rope. But the moonsuits had no thrusters for maneuvering, like the little thruster gun Ed White used on the Gemini 4 space walk and used by astronaut Michael Collins on the Gemini 10, or the AMU used on Skylab 3, or the Manned Maneuvering Unit and Safer units used on the Space shuttle. The Apollo 11 astronauts could have stayed outside for hours, and could have improvised ways of moving the spacewalker around by making a long pole out of shovels and tripods, or rigging ropes as handholds if they had to do something to the outside, like remove something stuck to the retrorocket or pulling on something that did not deploy, such as was done on one of the Skylab missions. On a Skylab mission, they also had an astronaut in the Apollo craft reach outside and pull on a solar panel which did not deploy on the Skylab, which is another trick the Apollo 11 could have done: use the Apollo thrusters to manuever the astronaut who is firmly held onto by someone in the craft while he reaches out the open hatch. They were pretty good at improvising, as shown on Apollo 13. Some astronauts have said that if they had been on the crew of the doomed shuttle Columbia and knew there was a fatal hole in the wing, they would have improvised a way to do an EVA and attempted to repair it, or to pack the cavity with a bag of water which would freeze and perhaps prevent the fatal reentry burnup. Edison 17:45, 18 January 2007 (UTC)

synosphere in fly ash

Does the fly ash generated by burning of bitumenous coal in Power plant boilers contents "synosphere" ? What are its characteristics & where is it used ?

"Synosphere" appears on Google only as a manufacturer of a PDA docking station. So if the company stays out of power plant furnaces, they should not show up in the fly ash. Does the word you are interested in have a slightly different spelling?Fly ash has lots of uses as an ingredient in concrete. I do not see anything in the article Fly ash which looks like "synosphere". Why do you expect to find such an ingredient in fly ash? Edison 18:34, 18 January 2007 (UTC)

Fly ash contains a lot of spherical particles, but nothing known to Google as "synospheres". But if you Google for "fly ash" and "spheres" or "microspheres", and you'll find thousands of articles. I'd guess the amount of the spheres produced depends on the non-carbon content of the coal. I recall UK adverts back in the early 1970s about "PFA" (pulverised fuel ash): this was produced by the kiloton by burning powdered coal in power stations, and the producers were keen to sell a waste product for use as a major ingredient in concrete... another thought arises from the name you use, and the possible source you mention: are you thinking perhaps of some kind of fullerene? (in that case, negligable amounts are produced if the coal is burning with sufficient oxygen for complete combution) Malcolm Farmer 00:15, 19 January 2007 (UTC)

Suppose someone were to set off a hydrogen bomb on the surface of the moon...

...what would the explosion and immediate aftermath look like? As there's no atmosphere, there'd be no mushroom cloud, so what exactly would happen to all the flame/ash/debris etc?

(Combining ideas from two different questions here...) --Kurt Shaped Box 06:52, 18 January 2007 (UTC)

High altitude nuclear explosion might give a hint. I'm not really certain, though the article is neat regardless ;) -- Consumed Crustacean (talk) 06:58, 18 January 2007 (UTC)

I suppose the explosion would go on until stopped by gravity, since there in no friction. | AndonicO ^{Talk · Sign Here} 12:20, 18 January 2007 (UTC)

There would still be a cloud - made up of surface material - how impressive would depend on the height of the bomb from the surface - or how far sub-surface. Rmhermen 16:01, 18 January 2007 (UTC)

I would expect that the sudden liberation of energy would look very much like a strike on the surface by a high speed (20 km-30km/sec) rock. It would produce a flash, throw up ejecta, and leave a crater. TNT equivalent says a 1 megaton nuke on the ground creates a 0.5 km crater, tiny compared to many on the moon. This is 4.184 × 10^15 joules according to Tonne of TNT. [11] says the meteor crater in Arizona was created by a 30 meter diameter meteor, the equivalent of a 50 megaton nuke explosion, and it is 1 km in diameter. Coincidentally, this is the size of the Tsar Bomba the largest bomb ever exploded. [12] is a story of a meteor impact on the moon, supposedly observed (photographed) in 1953, which resulted from a 300 meter asteroid and created a 1 to 2 km crater, in an explosion equivalent to a 1/2 megaton explosion. The numbers do not match, perhaps because of different assumed speeds and impact angles, (or because they are wild ass guesses). Edison 18:54, 18 January 2007 (UTC)

Are you saying the Tsar Bomba was dropped in Arizona? :-) |AndonicO ^{Talk · Sign Here} 20:56, 18 January 2007 (UTC)

That would have ben considered an unfriendly act at the time. Edison 06:19, 19 January 2007 (UTC)

It would still be considered so. :-) | AndonicO ^{Talk · Sign Here} 11:54, 19 January 2007 (UTC)

We also know what a high-speed impact with an airless, low-gravity body looks like from the Deep Impact mission - see this image. This impact was not in the megaton range - it was equivalent to just 4.5 tons of TNT, according to the article - but I imagine a megaton explosion would just be bigger and brighter. Gandalf61 12:35, 19 January 2007 (UTC)

Putting a man on Mars

Would they realistically call the manned mission to Mars program anything other than 'Ares'? --81.79.81.144 07:37, 18 January 2007 (UTC)

I don't know; they might even call it Mars, since he was also a god (almost the same as Ares from the Greek side of mythology). | AndonicO ^{Talk · Sign Here} 12:21, 18 January 2007 (UTC)

I'm sure Ares would get a mentioned somewhere (cf. the "Athena Science Payload" on the Mars Exploration Rovers). However - assuming NASA would be the agency who ran the mission - history would suggest a more bombastic mission name would be chosen. Rockpocket 08:08, 19 January 2007 (UTC)

What do you mean by "bombastic"? The moon was Apollo, another greek deity. | AndonicO ^{Talk · Sign Here} 11:56, 19 January 2007 (UTC)

Maybe they should send a woman too, so the trip is less boring. Edison 14:15, 19 January 2007 (UTC)

renewable energy

I can't seem to find a place source that says renewable energy resources are a good idea. They are, aren't they? --24.76.228.161 07:55, 18 January 2007 (UTC)

• Yes, they are. Try it the other way around. I'm positive you can find sources that say it's a bad idea to continue using fossil fuels. - 131.211.210.10 09:24, 18 January 2007 (UTC)

Thanks, fellow IP dude. --24.76.228.161 09:37, 18 January 2007 (UTC)

Hey there well i am currently conducting experimants on my own version of renewable energy it looks very promising now if only i can get enough money for a patent =( but yea there are sources out there that provide that however i wont say what im using till i get a patent =(Maverick423 20:51, 18 January 2007 (UTC)

New inventions in the last 40 years

Someone just asked me if I can think of any new (radical) inventions in the last 40 years. For the life of me I couldn't think of any. Remember that you have to disregard refinements or miniaturizations of existing inventions. For example you can't say "cellphone" as it uses microwave technology and miniaturized chips. Computers are just faster/smaller but all still use von Neumann architecture. I suspect quantum computing would be a new invention but it isn't mainstream yet. Sandman30s 09:08, 18 January 2007 (UTC)

So what? "cellphone" may be using microwave technology and miniaturized chips, but their application is still new as no one thought about using them that way before. Besides, most inventions are based on things we already know. I'd be hard-pressed to find anything that qualifies by your standard. - 131.211.210.10 09:23, 18 January 2007 (UTC)

Exactly, that is my problem too. Unlike true inventions such as the printing press, train (industrial revolution), car, aeroplane and computer (revolution); it seems we are slowing down as far as truly radical inventions go. Not that it's obvious to most. Technology seems to be changing ever faster on the contrary. In truth, technology is just getting more efficient or smaller. When are we going to see the next revolution? Sandman30s 13:41, 18 January 2007 (UTC)

I think the current revolution is in design and smart, eco-friendly engineering. Vranak

I would challenge the definition yet again. Classifying the printing press was a world-changing invention is very similar to classifying the cell-phone as a world-changing invention. There was paper and ink before the printing press was invented, much as there was portable RF communication much before 'modern' cellphones were invented. It's the *use* of existing technology in a novel way that makes for what you would seem to call a 'radical' invention. --66.195.232.121 15:50, 18 January 2007 (UTC)

Not just paper and ink but printing including moveable type existed way before the Guttenberg printing press. The Chinese were doing it since the 11th century Nil Einne 16:26, 18 January 2007 (UTC)

Depends of how you define "invention". A physical device? What about Internet, does that qualify? — Kieff 09:26, 18 January 2007 (UTC)

It would qualify except that it was "invented" over 40 years ago. It originated from arpanet in the 60's. Sandman30s 13:41, 18 January 2007 (UTC)

ARPANET became operational in 69, 38 years ago. :) — Kieff 08:00, 19 January 2007 (UTC)

Packet switching and other arpanet components were invented during the 60's, more than 40 years ago :) Sandman30s 12:39, 19 January 2007 (UTC)

Well, the internet itself is just the network isn't it? What about the World Wide Web/Hypertext on its own? That was invented in c. 1990. --Neo 15:01, 18 January 2007 (UTC)

If you classify http as an invention. I suppose you could define www as a world changing phenomenon. Then again would you class any type of software as inventions? Sandman30s 12:39, 19 January 2007 (UTC)

What about Wikipedia? It is a fairly recent "invention". --V. Szabolcs 21:36, 18 January 2007 (UTC)

It is software. See previous point. Sandman30s 12:39, 19 January 2007 (UTC)

No, it is software + a community! :) And.. what about (other) social "inventions"? Are they not considered inventions? --V. Szabolcs 07:30, 22 January 2007 (UTC)

If you are asking for a new technology invented in the last 40 years, I was going to say optical data storage, but our optical disc article says that the analogue optical disc was patented in 1961. Maybe if you qualify it with digital optical data storage. Our article on disruptive technology might give you some other ideas. Gandalf61 13:50, 18 January 2007 (UTC)

What I am failing to see is why taking a wagon and replacing the steam engine someone added with an internal combustion engine is more of an "invention" than taking a telephone and removing its analog components, its rotary dial, its wired connection and power supply and replacing them with battery power, digital component, wireless connections and touchpads? I don't think I agree with your history of inventiveness any more than your examples. Rmhermen 15:58, 18 January 2007 (UTC)

Because the combustion invention was a radical world-changing invention that threw out the steam engine. Sandman30s 12:39, 19 January 2007 (UTC)

I think MRI satisfies your standards. --bmk

Oh, and also Polymerase Chain Reaction --bmk

Actually, by that ridiculous standard of "invention" PCR doesn't really cut it; if I recall it is just a "combination" of certain techniques which had been worked out in the 1960s. I don't have a copy of Rabinows Making PCR on me at the moment but I recall this being central to controversy over authorship (some of the anti-Mullis people claimed that he hadn't really "invented" anything, just put a few new things together in a novel way, which of course counts as an invention under most people's definitions). Also, if you were being contrarian you could say that MRIs just exploit nuclear magnetic resonance, which was discovered many years ago indeed. You'd have a pretty dopey understanding of invention though if you used that sort of standard — turns out nothing was really invented! --140.247.240.75 18:34, 18 January 2007 (UTC)

Arguably, whatever is patented and provides royalties to its inventor is an invention. Other inventions are just given away for the public good. That some of its components or operating principles were preexisting is no different from claiming that fabricated stone tools were not inventions because they were an improvement on rocks found in naturally occurring useful shapes, or the Incandescent light bulb was not an 1870's invention because Volta made a copper wire glow in 1800. Among things I did not see 40 years ago, I find cell phones to be new and amazing inventions, from an era of looking for a pay phone and enough coins to make a call when my office paged me. The pager was an improvement over having to call in periodically to check for messages. The scanner is an amazing invention, as is character recognition, the photo quality home printer, the color plasma tv for homes, the MP3 player, digital cameras, flash memories which can store 128 meg in a thumb drive, digital camcorders, PDAs, videogames, Digital matrix encoded surround sound, gene sequencers, PCR, CAT scans, cloning, MRI, sonograms, digitally guided endoscopic brain surgery, Humalog, Lispro and Humulin insulin, selective serotonin reuptake inhibitors, and above all HeadOn (apply directly to the forehead: the ability to advertise a homeopathic product without making any medical claims whatever, and getting people to buy it.) Edison 19:16, 18 January 2007 (UTC)

All you're doing by defining an invention as something patentable is putting the definition into the hands of the people who write patent laws. This is a rather dubious definition of invention because 1. patent laws allow a lot of things to be called "inventions" that most people would be leery of (business practices, for example), and 2. not all inventions are covered by patents, as trade secrecy is sometimes a better economic alternative. --24.147.86.187 00:35, 19 January 2007 (UTC)

Please reread the part where I said "Other inventions are just given away for the public good" In no way did I say only patented things are inventions. Things kept as trade secrets are indeed another big class of inventions. Edison 06:22, 19 January 2007 (UTC)

Well GOOGLE HAS A LOT TO SAY ON THE TOPIC, and so does Wikipedia, apparently. Anchoress 06:32, 19 January 2007 (UTC)

Ok people my intention was not to start a debate on the definition or standards of inventions. I am stating that I am not impressed with any current technology as it is all an improvement of existing core technology. Electricity was a radical invention that changed the world, as was nuclear energy. I disagree that the combustion engine was not new, it changed the world, as did the Wright Bros flight engine. The invention of antibiotics changed the world. Are we close to a revolutionary invention that will change the world or is man on a "downward" spiral towards the incessant need for economically inspired improvements? Sandman30s 07:30, 19 January 2007 (UTC)

Just wait for the fusion power plant to become operational. It will surely change the world. And if mankind is not able to build it soon enough, it will too change the world into a second medieval age. --V. Szabolcs 08:45, 19 January 2007 (UTC)

Agreed. Add to this quantum technology. Superconducting in mainstream usage. Mainstream nanotechnology could be a moot point. And of course anything that revolutionizes space travel. I wonder when mankind would move on from a type 0 civilization to a type 1? Sandman30s 12:39, 19 January 2007 (UTC)

Here's the problem: you've created a set of conditions that has never existed at any time in human history. Everything is a modified version of something that came before it. Your example of the combustion engine supplanting the steam engine is quite telling. How different do you think they are? Steam engines have cylinders, pistons, and cranks. A modern internal combustion engine operates in essentially the same manner except that the work is done directly ("internally") by the expanding gas, rather than indirectly by the expanding steam. And have steam engines been thrown out? Nah, we just modified them a bit and called the steam turbines.

Part of the problem might simply be perspective - you've seen how modern inventions get tweaked and recalled and modified endlessly, but for 'historical' inventions you've been deceived by lazy teachers who can say "James Watt invented the steam engine" while apparently not knowing that he only modified an existing design that had been modified for decades before him.

James Burke did an excellent series thirty years ago called "Connections" that examined this error in thinking in depth. It's available on DVD these days and well worth the watch even today. Matt Deres 00:35, 23 January 2007 (UTC)

• Blue laser technology. Combat UAVs like the armed Predator. Mieciu K 14:04, 24 January 2007 (UTC)

Tonsilitis and the common cold

Is there a connection between cold and tonsilitis? It often seems that people with colds develop tonsilitis. Could it be an opportunisitic infection, or is it the cold virus itself which causes symptoms similar to tonsilitis? —LestatdeLioncourt 13:51, 18 January 2007 (UTC)

Here's one possible explanation. The palatine tonsils are part of the surveillance arm of the immune system. Just like lymph nodes, they tend to swell when responding to infection (mostly due to B cell proliferation). --David Iberri (talk) 16:20, 18 January 2007 (UTC)

Makes sense. But I believe it's the T cells that are more active in the immune response against viral infections. —LestatdeLioncourt 17:12, 18 January 2007 (UTC)

Of course I totally overlooked the "common cold" part of your question. :-) --David Iberri (talk) 17:21, 18 January 2007 (UTC)

If you want to read some incorrect, speculative 'original research' on the issue, check out the Reference Desk talk page. Vranak

Someone please apply that darned medical advice template. But from longtime personal experience, a viral infection (cold, flu) which persists seems to irritate the mucosa and the drainage seems to irritate the tonsils, perhaps making them more subject to bacterial infection. Repeatedly I have had colds which went on and on, were replaced by bacterial sinus infections or tonsillitus, and finally I developed a strep infection which was cured with antibiotics. Coincidencce? I don't THINK so!Edison 19:21, 18 January 2007 (UTC)

Please don't apply the medical advice template. None was asked for, and none was supplied. - Nunh-huh 19:27, 18 January 2007 (UTC)

Asking questions regarding pathology is not asking for medical advice. The difference is vast. —LestatdeLioncourt 19:46, 18 January 2007 (UTC)

Mine swell up terribly everytime I am sick and are "very large" according to one doctor I had seen about it. X [Mac Davis] (DESK|How's my driving?) 21:38, 18 January 2007 (UTC)

Acetylcholine

While researching the effects of nicotine on small cell carcinoma, I found a reference to acetylcholine, which was identified as "a neurotransmitter" that may also stimulate cell growth in tumors. I could not find anything further on acetylcholine's function in the nervous system. Could someone please add this? Hcbowman 15:41, 18 January 2007 (UTC)

Acetylcholine is the major neurotransmitter at the neuromuscular junction and a couple other sites in the brain (eg, basal forebrain). Acetylcholine should already contain this. --David Iberri (talk) 16:12, 18 January 2007 (UTC)

Mea culpa. Typo when I searched. Thanks! Hcbowman 18:50, 18 January 2007 (UTC)

Blue moon in February?

When would be the next year that there would be a full moon on the evening of January 31st and a full moon on the evening of February 29th (or is that even possible)?

Time

I don't see any reason why it would be impossible which suggests it will occur Nil Einne 16:33, 18 January 2007 (UTC)

On 31 January 2048 there is a full moon at 0:16 ET and another on 29 Feburary at 14:39 ET. That doesn't quite meet your criteria, but I suspect that is about the nearest you will get to a blue moon in February. (I have given ET rather than UT as we do not know the value of delta T so far in advance.)--Shantavira 16:47, 18 January 2007 (UTC)

I take it then that by ET you mean ET rather than, say, ET. Note that the original poster did not specify a time zone and might be assuming his/her local time zone, which we weren't given. --Anonymous, January 18, 2007, 18:26 (UTC).

Why does cuticle skin come off so easily?

That is, the skin on the sides of the nail, not on the top. I almost always have cuticle issues. Much help appreciated ! Xhin 18:23, 18 January 2007 (UTC)

See Nail biting. I believe they make bitter tasting products to be placed on the cuticles to remind one not to bite them, if that is the issue. Picking at them with the other fingernails may just be a nervous habit of self stimulation. Edison 19:26, 18 January 2007 (UTC)

Skin is made up of layers of cells covered with a (relatively) thick, horny layer of keratin. This keratin protects against abrasion, but does slough off rather easily. On most of the skin, the keratin is constantly falling off and being replaced. The nail itself is also made of keratin, but this keratin is thicker and has a high sulfur content, making it harder. Once the nail desiccates, it becomes clear and resists tearing. The part of the nail usually referred to as the cuticle, the eponychium, is made up of the same, high-sulfur keratin as the nail itself, however, since this layer is very thin, it is much more fragile. For most people, this "cuticle" never fully desiccates, and is easily torn. When the eponychium fully dries, it becomes brittle and flakes of easily. Tuckerekcut 00:53, 19 January 2007 (UTC)

Depending on your sex and style this may not be a viable option for you, but I find that - for some reason - keeping my nails coated with nail polish makes my cuticles more manageable and less likely to develop pickable ridges. Anchoress 00:56, 19 January 2007 (UTC)

I went through a period of horrible hangnails, but after drastically improving my diet, my cuticles are now beautiful and healthy. Vranak

Group and phase velocities...

Could someone explain the difference between the two, for a beat wave produced by two waves of similar frequency? I've read the articles, but to me, the definitions didn't shed any light. Which one is the velocity of the "larger" amplitude, which moves along the whole group (some might say :P) of waves (I'm tempted to pick this as group velocity because of the name, but I'm unsure), and which is the velocity of the individual waves inside this envelope?

Thanks, Icthyos 18:59, 18 January 2007 (UTC)

See Dispersion (optics) which has a somewhat understandable explanation, in addition to Phase velocity and Group velocity. The graphic demo at [13] may help. I wish it had been around when I took the engineering course in fields and waves. Edison 19:35, 18 January 2007 (UTC)

We've had this question a few times! It is difficult to understand. Here's a good one we had in August 2006.[14] X [Mac Davis] (DESK|How's my driving?) 21:35, 18 January 2007 (UTC)

So, the group velocity is the velocity of the wave that I mentally "sketch" onto what is caused by the varying amplitudes of the higher frequency waves? And the phase velocity is that of the "component" waves that make up the envelope? With the analogy of the AM radio transmission: the phase velocity is the speed of sound, since it is the wavelength of the light wave that is being modulated, and the group velocity is the speed of sound?

Thanks, that was a great help. (...unless what I just posted was wrong. Then I'll entirely reverse my thinking!) Icthyos 23:31, 18 January 2007 (UTC)

request information on radiation posion

Hey guys

well basicly I want to make a request on radiation Poison

i have read the articles however there is one problem yes the symptoms are stated and all but does anyone know how it FEELS to be in the proximity of radiation or to touch something radio active. in other words do you feel heat from something radio active? do you feel a weird nausia feeling while you are reciving a radio active dose (regardless of its potency) what does a person feel before the symptoms arise and when you are acctually reciveing the dose is what i want to knowMaverick423 19:06, 18 January 2007 (UTC)

See our article on radiation poisoning for a discussion of symptoms associated with various doses. Note that even for lethal doses, symptoms can take minutes or hours to appear. (Very high doses will be followed by nausea within a few minutes.) You have to get up to about a hundred times the lethal dose of ionizing radiation to 'feel' the damage as it occurs (immediate disorientation followed by coma).

Radioactive materials may be warm to the touch, but what you feel is simply heat produced by radioactive decay, rather than the ionizing radiation itself. TenOfAllTrades(talk) 19:35, 18 January 2007 (UTC)

OMG thank you so much this is exactly the kind of information i was looking for! someone should add this to the article for future refrence. i mean yea the article says this and that about the effects (after) you come in contact but they dont mention anything about the time during your inital contact! thanks again TenOfAllTrades Maverick423 20:30, 18 January 2007 (UTC)

one more question

hey its me again well basicly i want to know (that i dont belive i saw in the article) what is the range of radiation? is it always imminate close or touching distance or can you be like a mile away from it and still get posioned (not including the mention of nuclear bombs i know that one already) but just basicly the radation itself with no propellents to move it far away just the range of the most / or a highly radioactive material sitting on a table with out nothing stopping the radiation from spreading. how far can that radiation reach? Maverick423 20:46, 18 January 2007 (UTC)

Different types of radiation have different ranges. alpha rays are stopped in a very short distance by air. gamma rays OTOH can go much farther. Theresa Knott | Taste the Korn 20:54, 18 January 2007 (UTC)

are we talking in terms of miles for gamma rays or feet meters?. Maverick423 20:56, 18 January 2007 (UTC)

They are blocked by meters of concrete and several centimeters of lead. They certainly will be stopped by air. This is why we didn't detect gamma ray bursts until we had satellites. But I don't know how much air is needed. Theresa Knott | Taste the Korn 21:22, 18 January 2007 (UTC)

Alpha particles are helium nuclei and can be stopped by a piece of paper, beta particles are electrons/positrons and can be stopped by a piece of aluminum foil, gamma rays are photons in the gamma range, and takes 6 inches of concrete to decrease their intensity by 50%. Alpha radiation is unharmful to the outside of a person since it is absorbed within micrometers of the skin. In order of potency the list goes: alpha, beta, gamma. X [Mac Davis] (DESK|How's my driving?) 21:29, 18 January 2007 (UTC)

Thanks much for the information guys you are all great!! Maverick423 21:40, 18 January 2007 (UTC)

oh and dont worry these arnt work related or anything after all i finished school 2 years ago they are just questions burning in my mind. when u see movies where radiation is involved you see people trying to get as far away from the radiation as possable or they look like they get hit by something sometimes when they see a radio active substance come into contact with their hands or jus from simply looking at the matiral . this is what got me asking these two questions and i am thankful that you all anwsered them =) thanks again!Maverick423 21:43, 18 January 2007 (UTC)

Not mentioned above is that even when radiation is not being stopped by something, its intensity diminishes in proportion to the square of the distance, so if you are initially 1 foot from a gamma source and you move out to 50 feet away, that is 50 times farther and 50 squared is 2500, so the radiation is 1/2500 of what it was. This is just for geometric reasons -- the same amount of radiation is spread out over a spherical region with 2500 times the area -- and also applies to things like light and sound. --Anonymous, January 18, 2007, 22:58 (UTC).

...in a vacuum. Even in low pressure that doesn't hold close. X [Mac Davis] (DESK|How's my driving?) 23:18, 18 January 2007 (UTC)

Yes but it will always drop off at least by that much. Theresa Knott | Taste the Korn 23:43, 18 January 2007 (UTC)

Some radiation can go very far distances indeed. Cosmic rays can travel millions of miles (most of which in a vacuum, though) and still be very highly energetic. --24.147.86.187 01:40, 19 January 2007 (UTC)

This may seem picky, but the distinction is the basis of 20th century physics - cosmic rays do not lose 'energy' as they travel through the vacuum, although they do lose 'intensity' as ${\frac {1}{r^{2}}}$. --18.214.1.72 02:02, 19 January 2007 (UTC)

After an atomic blast, the radiation carried in fallout particles (formerly the ground, houses, people, trees, etc near the blast) can travel hundreds of miles downwind in a deadly plume. The radiation from such a particle may fall off as described by the inverse square law, but that law does not describe bomb fallout or particles released from a nuke accident such as Chernobyl. Edison 06:27, 19 January 2007 (UTC)

Great info guys thanks a ton. if only wikipedia was available when i acctually had homework to do lol that would of been great. in anyways thanks alot you all!! Maverick423 17:08, 19 January 2007 (UTC)

Time and thought

One thought that occurred to me today was that our psychological perception of time must be dependent on how "fast" we think, so to speak. Now I know that there are objective ways of defining time intervals (e.g. the second and the oscillations of Cesium's electrons), but in the end isn't what really gives meaning to the flow of time how fast we perceive it (à la relative motion)? If we thought slower, would events unfold at a slower rate according to our perception? Conversly, would we experience a "faster" flow of time if we had superior mental processing abilities? —LestatdeLioncourt 21:26, 18 January 2007 (UTC)

Just want to fix a bit of your reasoing here: if we thought slower, we'd perceive events and time as faster, and not slower. You wouldn't keep up with external time. — Kieff 23:54, 18 January 2007 (UTC)

You're right. It should be the other way around. My mistake. —LestatdeLioncourt 09:26, 19 January 2007 (UTC)

You may find our article on Time#Psychology informative and useful in finding other sources. Hipocrite - «Talk» 21:34, 18 January 2007 (UTC)

I have heard that outstanding athletes (e.g. Wayne Gretzky), who presumably have superior mental abilities (at least with regards to their particular sport) actually experience crucial events in a game at a lower speed than usual. Vranak

This concept is explored in a number of fiction works, usually by means of explicitly "speed-up" drugs or special abilities. I always wondered if it's possible to artificially speed up our thoughts (without other effects), and what problems that could bring us. — Kieff 23:54, 18 January 2007 (UTC)

Totally relevant. Vitriol 01:26, 19 January 2007 (UTC)

Somewhere in the Lensman series there is a description of the "speed of thought" being faster than the speed of light! In fact, human thought processes are slower than we tend to notice. Books such as The Astonishing Hypothesis discuss experiments that have measured how long it takes for people to respond to sensory stimuli and become consciously aware of them. Ultimately, the "speed of thought" depends on how quickly metal ions can diffuse through water at body temperature and the overall size of the brain. The electrical signals that carry information in the brain depend on the diffusion of charged ions through pores in the membranes of neurons. --JWSchmidt 02:28, 19 January 2007 (UTC)

Elderly relatives have insisted to me that the older they get, the faster time sems to pass. When they were young, a year lasted a long time. When they are elderly, the years go by zip zip zip. A baby seems to grow up quicker than when the observer was young. If their thought process slowed down, that could account for time seeming to go faster per the above. Edison 06:31, 19 January 2007 (UTC)

I've noticed this same phenomenon, but my garden theory is that we perceive life "ratiometrically". When we were little, the eleven months between now and Christmas represented, say, 25% of our life and so seemed like a long, long time. Now, it represents less than 2% of my life, so it seems rather quicker. Plus, I spend so much time on Wiki that it all passes like a blur anyway... Atlant 12:42, 19 January 2007 (UTC)

A lot of our senses are logarithmically scaled. We notice change, not absolute value. If you double the intensity of a light, you'll feel a certain increase. Once you're accustomed with that intensity, a second doubling (so now it's 4x) gives the same perceptual increase of intensity. So perhaps that's exactly how it goes with time: we just need more passed time to feel the same way than we did before. Life is logarithmic. That phrase has a nice ring to it, doesn't it? — Kieff 13:50, 19 January 2007 (UTC)

Here is an experiment you can conduct. I have done it many times and it works great for me. Get a quartz watch, digital of with hands, does not matter. make sure if it's digital that it reads out the seconds. Stare at the watch looking at the seconds going by and concentrate trying to speed up your "internal thoughts". This may take some practice but one can learn to do it. While one is speeding up ones thoughts, one can actually "observe" the speed up the seconds ticking by changing. It really works. Zeno333 08:17, 20 January 2007 (UTC)

January 19

Attacked by aliens

In reality, what defensive measures does humanity have in place in the event that the earth gets attacked by hostile extraterrestrials? I'd be amazed if the possibility has never even been considered by the US/Russians seeing as though we've been advertising our presence and the location of our planet for the past century or so by emitting radio waves into space. We've even sent spacecraft out of the solar system containing information that explicitly states how to find our homeworld. --84.65.149.111 00:03, 19 January 2007 (UTC)

Will Smith. Seriously, however, a commonly held correlary to the Fermi paradox is that if there was an alien civilization that had the technology to invade us, they would have perfected interstellar travel. Since we have not even perfected intrastellar travel, it is highly unlikey we could stand against an alien invasion, regardless of preparation. Hipocrite - «Talk» 00:13, 19 January 2007 (UTC)

Moreover if an alien species has perfected interstellar travel, why would they want to subjectate the human race? I don't see why aliens wouldn't have a sense of decency. Vranak

Maybe they think like us (we've not exactly got the best track record when it comes to dealing with civilizations less advanced than our own on earth)? Maybe they want the resources, the slave labour and the lebensraum? Maybe they want to 'save our souls'? --84.65.149.111 00:37, 19 January 2007 (UTC)

I would think that a species that had developed such high technology would also have a highly-developed sensibilities and ethics. This has certainly been the case in human history; as technology improves, so does morality. Vranak

Has it? The 20th Century was the cruelest and bloodiest in human history. It doesn't look like the 21st is going to be much better the way things are going. As technology improves, we just find ways of using it to kill people more efficently. --84.65.149.111 00:50, 19 January 2007 (UTC)

I understand your pessimism, but consider some of the tortures that used to be commonplace but are now unthinkable: brazen bull, Pear of Anguish, Hanging, drawing, and quartering. Vranak

High technology does not correlate with high values. The Soviet Union developed incredibly sophisticated military technology under a system of slave labor. They couldn't keep people fed but they could make ICBMs. High technology is no guarantee of civility, there is no correlation at all. And I don't think any of those tortures you named were "commonplace". The only one which seems to have been used with any regularity was the latter, and even that was reserved for a very small number of offenses. And I'm not sure that getting ones limbs blown off by artillery is any more humane. Napalm does not feel better than being boiled in oil. --24.147.86.187 02:04, 19 January 2007 (UTC)

I am thinking from a historical perspective, not a geographical one. Anyway, the tortures I listed require someone being right there with their victim, condoning a continuing anguish. An arm blown off by an artillery shell is certainly gruesome and inhumane, but it's not like the person firing the cannon means to do it. Burning someone at the stake or cruxifying them hardly leaves any doubt as to intent. Vranak

This thought has occurred to me before, and I thought, what if we gave medieval European countries nuclear weapons? Even if we also gave them the knowledge of radiation poisoning, I bet Europe would have been a nuclear wasteland in a month. Imaninjapirate^{talk to me} 23:17, 20 January 2007 (UTC)

I don't know whether to point out the impossibility of this proposition (unless you know something about time travel we don't), or to say that humans were never so stupid as to pointlessly obliterate themselves. Vranak

Why is it often assumed that alien technology, if it exists, exists for aggressive and hostile purposes? JackofOz 00:30, 19 January 2007 (UTC)

Because if everyone assumed that the aliens were peaceful, they could attack us and we'd never expect it? I know for certain that if a fleet of alien spacecraft entered the solar system on a course for earth, every single ICBM on the planet would be locked on and waiting - just in case - even if they were broadcasting messages of peace beforehand. --84.65.149.111 00:41, 19 January 2007 (UTC)

The Earth won't get attacked. Signals from early transmissions of Walker, Texas Ranger will have gone quite far into space by now, and they are doing a fine job as a deterrent. Readro 00:45, 19 January 2007 (UTC)

Even if we were attacked, we wouldn't be enslaved. Slavery in a modern civilization is very inefficient, even if you don't consider the enormous amount of training required to adapt us to their technology/language/culture. So we'd just be disposed of - feel better now? Clarityfiend 07:11, 19 January 2007 (UTC)

I recommend you all to read some Stanislaw Lem novels. It could help to imagine aliens who are really different, not like us just with slightly different organs or skin color. The idea that they need our resources is just a setup for some stupid action movies. In reality, considering the scarcity of life in the universe, why would the aliens need to travel hundreds and thousands of light years just to battle us, when there are a lot of uninhabited planets on the way to be conquered more easily without a war. --V. Szabolcs 08:35, 19 January 2007 (UTC)

This question has been on many minds for decades now, popularized by War of the Worlds since the 50's. If we are invaded our technology and defence would be far inferior to the invaders, as they would already be a spacefaring race. Even Star Trek scenarios of grandiose space battles are very unlikely as the level of technology would be hugely different if you consider the odds... the universe is billions of years old and modern man is barely 2,000 years old, imagine what a 100,000 year old race would have achieved? What about a million-year old race? Highly advanced and probably evolved or transcended into beings of energy or whatever your imagination can muster. The question is, would it be likely they would want to invade and exterminate us like bugs? This depends on a number of factors. Are they genetically aggressive or expansionist? Do they need to expand for living space? Do they need natural resources or worlds that can support life? My personal hope is that there is some sort of galactic council of aliens and they are waiting for us to evolve so that we can be invited to join the council. Probably some sort of non interference policy being adhered to. Maybe we are being monitored (UFO's). So much more to say but so little time to type. Sandman30s 08:44, 19 January 2007 (UTC)

Who says aliens are advanced? They might be some form of microscopic life form that no one will ever notice. Stupid science-fiction films are to blame for misinforming (probably) millions of people. They should make a good movie for once... | AndonicO ^{Talk · Sign Here} 12:05, 19 January 2007 (UTC)

Infinite universe. Infinite number of stars. Infinite number of stars with orbiting planets. Infinite number of life-bearing planets. Infinite number of life-bearing planets with intelligent life. Infinite number of advanced civilizations. QED. ;) --Kurt Shaped Box 12:23, 19 January 2007 (UTC)

We would send Sheriff Bush out to defend us, Mano-a-thingo. My money would be on the thingos, though.

Atlant 12:47, 19 January 2007 (UTC)

The US, Russia, and this week China have sent up missiles and destroyed satellites, just to show they can. These coiuntries could take down spy satellites to blind their opponents, weather satellites to deny that modern benefit, and communication satellites (the horror!). The Bush administration does not look favorably on China having that capability, but I'm not sure what remedy he will apply. Stop paying out debts to them or stop buying all our manufactured goods from them maybe. So if they attacking space aliens would stay in simple orbits and not deploy any countermeasures, they could get whacked. Edison 21:10, 19 January 2007 (UTC)

Have you already thought that aliens could like to keep us as pets? Mr.K. 21:42, 19 January 2007 (UTC)

In the very unlikely event that an intelligent alien race could and would come to our planet, and in the unlikely chance they would attack us for no apparent reason, I have no doubt that we could defend our selves very effectively no mater there level of technology. This is because the laws of physics still work the same all over the galaxy. For instance earths nuclear weapons can be built just as strong as any alien nukes could. No mater whether you have ray guns or not a nuke is still an extremely powerful deterrent. Actually I would be more afraid of humans destroying the aliens than vice versa. S.dedalus 23:18, 19 January 2007 (UTC)

There's no reason to think that a civilization that advanced doesn't have extremely advanced point-defence capabilities. -- Consumed Crustacean (talk) 23:44, 19 January 2007 (UTC)

Perhaps, however considering how little armor and materials have developed over the entire coarse of human history I think it is statistically unlikely that even the most advanced of races would be shielded from the effects of a Tsar Bomba. Also I think most carbon based life forms would be adversely effected by that much radiation. Because of the finite speed of light, interstellar travel is also apt to be very slow. This would give us another tactical advantage as reinforcements might take centuries to arrive, and logical communication would be all but impossible. In any case, I’m not saying there’s not a chance of invasion but I suspect ET’s would try to talk first. S.dedalus 06:45, 20 January 2007 (UTC)

Good point. We launch the missiles, they shoot them down in the upper atmosphere with particle beam technology, the things break up and scatter radioactive material over half the globe. If it was a computer game, the 'BAD END' screen would come up at this point... --Kurt Shaped Box 22:04, 20 January 2007 (UTC)

Live by the sward. Die by the sward. ;-) S.dedalus 03:51, 21 January 2007 (UTC)

Animal Tracks

It has finally snowed here in Monmouth County, New Jersey. But just a dusting. I went to bring the trash out and noticed strange animal, possibly bird tracks on my driveway. Here are two photos: [15] [16]. They are quite large, 2 or 3 inches across. Any ideas? --Russoc4 00:21, 19 January 2007 (UTC)

Ski polls? They aren't a bird, birds have at least one claw facing back. --liquidGhoul 03:00, 19 January 2007 (UTC)

I see a curved mark facing backwards in at least some of the prints. StuRat 01:40, 20 January 2007 (UTC)

Hehe, you might want to read the above post. :) --liquidGhoul 03:01, 19 January 2007 (UTC)

What post? Edison 06:34, 19 January 2007 (UTC)

Aliens...still, they are really weird. The closest I can find is here [17], third row, third from the left. No clue what it is though. --71.250.199.10 14:51, 19 January 2007 (UTC)

The alien post. Don't worry, my joke didn't work :( --liquidGhoul 16:02, 19 January 2007 (UTC)

Anamorphic widescreen

If I watch an 'anamorphic widescreen' DVD on a TV with a 16:9 aspect ratio, what difference would I see from watching an ordinary widescreen DVD? Would the 'anamorphic' picture fill more of the screen (i.e. produce smaller black bars)? Or would both DVDs take up the same amount of space on the TV screen, but with the anamorphic one offering a clearer image? I've been wondering about this. Thanks!

Anamorphic and aspect ratio are two different things. A movie filmed in 16:9 will play with no black bars on a 16:9 TV, a movie filmed wider, like 2.2:1, will have black bars, anamorphic or not. The anamprphic will have a better picture however. Vespine 02:49, 19 January 2007 (UTC)

A compressed virtual disc

"'Moved to Computing desk

Amplitude of EM waves

The energy of an electromagnetic wave is related only to its frequency (or wavelength), as given by E = h×nu. I hadn't thought until recently about the amplitude of the wave. I would have thought that a wave with a larger amplitude would have more energy than a smaller wave of the same frequency and wavelength. Can this situation exist? What controls the amplitude of EM waves? Or, do all EM waves have the same amplitude? --BenC7 02:02, 19 January 2007 (UTC)

Actually, E = hv gives the energy of a photon, not of the electromagnetic wave. Take a look at radiant energy. Basically, you can think of amplitude as the "amount" of photons of a wave, each photon carrying a bit of energy proportional to their frequency. — Kieff 02:30, 19 January 2007 (UTC)

Hmm, perhaps I should rephrase. Clearly, constructive and destructive interference will change the amplitude of a wave at a particular point in space. But what about a single wave? For example, does a single gamma ray (or one photon, if you want to think of it that way) have the same amplitude as a single radio wave? --BenC7 10:57, 19 January 2007 (UTC)

Heats of combustion of common alkanols

In a recent experiment at school I calculated the molar enthalpies of combustion of four common alkanols: methanol, ethanol, 1-propanol and 1-butanol. Butanol seemed to be somewhat of an outlier as the result I obtained was ten times what I got for the other alkanols. I was just wondering where I can find information listing molar enthalpies of combustion of common alkanols and what the reason is for differences between each alkanol in terms of heat of combustion? thanks Wbchilds 03:32, 19 January 2007 (UTC)

You obviously need to redo your calculations. This famous practical is supposed to show that there is a regular rise in molar enthalpies of combustion, which is ascribed to each one having an extra -CH₂- group. --G N Frykman 07:20, 19 January 2007 (UTC)

I love you more than....

Ok fairly frivolous question but bare with me. As inspired by Sarah Silverman's funny song, I'm making up a list of things that love things which are scientific or academic in nature. The best way to explain is to give you a couple of examples I already have:

I love you more than:

hydrogen loves oxygen (currently my favourite one)
positive loves negative
protons love electrons
entropy loves increasing

I'm sure you get the idea. I also thought 'black holes love light' but that's a bit, I don't know, dirty sounding ;). So no stupid ones, I'm sure we could make a list a million long of really crap things like "Balls love rolling down a hill becuase of gravity", but that's not really clever or anything, so I'm looking for as clever or cute as you can think of, any ideas? I promise these will be used for good not evil, thanks in advance. p.s. no this isn't homework!;)Vespine 04:01, 19 January 2007 (UTC)

(from a health point of view)...more than:

cavities love sugar

plaque loves teeth

dentin loves bonding agent

gum loves braces

I recognize that I may be the only one that finds this amusing. - Dozenist talk 04:16, 19 January 2007 (UTC)

Mice Love Rice? -- 我♥中國 04:44, 19 January 2007 (UTC)

Sorry to rain on your parade, Vespine, but I am not at all sure that hydrogen does love oxygen, certainly not in any exclusive sense. Sure, the relationship starts with a bang, but that whole water molecule thing is a ménage à trois. Plus hydrogen has some very intimate extra-molecular relationships - see hydrogen bonding. As soon as hydrogen sees a more attractive partner or a bit of electricity, it abandons poor old oxygen (hydrolysis, electrolysis). In fact, hydrogen will bond with more or less anything that will take its electron or give it one - see Hydrogen compounds. So maybe this isn't such a good example after all ! Gandalf61 08:03, 19 January 2007 (UTC)

I wasn't trying to imply hydrogen won't bond with anything but oxygen, but it takes more energy to break the chemical bonds in water than to make them. Vespine 01:28, 20 January 2007 (UTC)

Heh i dont know but i like this its cute. so Gandalf61 says that hydrogen is a cheat eh. he couldnt be more right. bad hydrogen heh. maybe hydrogen is just misunderstood maybe it needs to experiance more love ok thats enough of that. as for a love thingy how about

Hydrogen, you ignorant slut!. Clarityfiend 23:03, 19 January 2007 (UTC)

stains love shirts food love floors cars love speed Maverick423 16:53, 19 January 2007 (UTC)

WE ALL LOVE THE INTERNET! Ovation plz. Vitriol 22:21, 19 January 2007 (UTC)

Fat kid loves cake? :> -Obli (Talk)^? 22:45, 19 January 2007 (UTC)

Odd color perception with a tone of violet

There's a particular tree around here from the genus Tibouchina (Tibouchina multiflora, in particular) which flowers have a color similar to this violet\purple tone. But, I'm not quite sure why, the color has a completely different effect on me than any other.

It really burns my vision, in the sense that I see afterimages and sometimes trails of the petals for quite a while afterwards. Another curious thing is that the color seems to "blur" everything else, and leaks out to the rest of my vision (particularly when I see several petals scattered on the floor.) It's like the color blinds all others. It also seems to be the last color I can perceive with my photopic vision (it's as if I could see it with the corners of my eyes.) It's quite an interesting feeling overall. It can be distracting, but nothing worth worrying about.

So, I was wondering what could this be... I wanted to know if there is such thing as color hypersensitivity? Maybe my cone cells and rod cells are all affected by high energy photons of the violet light in a different way? Or maybe the petals are particularly good reflector of an usually invisible part of the spectrum, which I happen to be a more sensitive to?

Well, I don't know. Any ideas of what's this? I asked other people if they have the same thing, but I couldn't find anyone else who admitted perceiving this tone differently from the others. Even the ophthalmologist I go routinely never heard of this sort of thing. — Kieff 10:40, 19 January 2007 (UTC)

The way you describe it as burning an afterimage into your sight probably indicates that photons of this particular frequency for some reason have an abnormal effect on the reformation of the rhodopsin molecule in your photoreceptor cells (the article Retinal explains the process). Maybe you have an abnormal form of the molecule, due to some genetic mutation? Does any of your parents/grandparents report the same hypersensitivity? —LestatdeLioncourt 11:25, 19 January 2007 (UTC)

I already theorized it could be genetic. If so, then it's either recessive, since my parents deny any such effect, or a specific mutation of myself. Since violet photons are more energetic than the others in the visible spectrum, maybe a slightly different molecule is having a whole new reaction against this higher energy? — Kieff 11:58, 19 January 2007 (UTC)

It's much more probable that a point mutation resulted in a slightly different, less efficient version of your opsin (in the sense that high-energy excitation prevents it from reassuming cis form), than for you to have synthesized a whole new molecule and developed a whole new method of perceiving color. The mutation doesn't have to be inherited, either. It could have taken place in the gametes of your parents, in which case it would more likely be dominant, and none of your parents would have it (see the mutation article, which might be helpful). If you can't find anyone in your family with a similar condition, then this is the more likely scenario. —LestatdeLioncourt 13:37, 19 January 2007 (UTC)

I think so... But it'd be nice to know of anything of the sort on record, and to look more into it. — Kieff 14:00, 19 January 2007 (UTC)

We are not able to provide you with medical advice. If you are concerned for your health or safety, you should seek professional medical attention. Hipocrite - «Talk» 13:22, 19 January 2007 (UTC)

I think Kieff is just trying to understand the biochemical/genetic origin of his peculiar condition. Based on how he describes it, it doesn't seem to be a medical condition warranting professional medical attention. —LestatdeLioncourt 13:37, 19 January 2007 (UTC)

Oh please, I'm well aware of the RD policies, but what I'm asking is not medical advice, at all, I'm not concerned or anything. I just want to know if anyone out there ever heard of this sort of thing, and just so I can look more into it. And I've been to an ophtamologist already, he never heard of anything like this, and didn't seem to be very interested on it either. — Kieff 13:30, 19 January 2007 (UTC)

Kieff your not the only one that has this experiance. I too have it even right now while i was typing and reading i still see the after image of the color that you displayed. It can be quite annoying and kinda hazardis when your driving. I personally dont know what this condition is called but i do know that im the only one in my family to have such problems with colors like this. so it cant be genetic. I do however wear Glasses if that can explain anything (although i doubt thats the problem) however i had this problem even before the glasses. well in anyways i also want to know what this is calledMaverick423 15:51, 19 January 2007 (UTC)

I don't have such a strong effect as you describe, but this shade does seem to be rather more insidious than your average colour. Daniel (‽) 21:21, 19 January 2007 (UTC)

Well, the color in a monitor doesn't do anything to me, and I don't think it should. The monitor is sending red and blue photons giving me the violet perception, but still they're not violet photons. — Kieff 02:25, 20 January 2007 (UTC)

Great White shark and sea lion

The article about the Great white shark states that "[..] This tactic allows the animal to avoid combat with dangerous prey, such as sea lions". I can't imagine how a sea lion can be dangerous for such a huge and well armed shark. Any ideas? Thanks. --Taraborn 10:53, 19 January 2007 (UTC)

That was probably vandalism; I've seen tons of footage of sharks attacking sea lions. | AndonicO ^{Talk · Sign Here} 12:09, 19 January 2007 (UTC)

Perhaps it's trying to express the concept "Prey which can themselves potentially do damage to the shark"? I'd imagine a sea lion is more dangerous to the shark than, say, j-random 1/2-metre fish.

Atlant 12:52, 19 January 2007 (UTC)

Some sharks, but not Whites. Their hide is as tough as aluminum siding. Pretty much the only animals that can do damage to whites are people, orcas (and maybe other toothed whales if they were interested), and other whites. Anchoress 13:04, 19 January 2007 (UTC)

So, do you think that a great black-backed gull defeat a great white in combat on land? :) --Kurt Shaped Box 13:24, 19 January 2007 (UTC)

If you attached the gull to a jackhammer or a harpoon, definitely. Anchoress 13:48, 19 January 2007 (UTC)

On land, unless the great white is related to the lungfish, the gull wouldn't have to do anything. All hail the mighty gull. (Deduct 20 points.) Clarityfiend 16:00, 19 January 2007 (UTC)

Even if it was, the gull could just go for the eyes (they're good at going for eyes) and incapacitate it - no aluminium siding there. --Kurt Shaped Box 18:41, 19 January 2007 (UTC)

Radioactive poisoning and possible cures

Dear Sir/Madam

Please name some radioactive isotopes that if consumed can poison and kill a person?

Also, are there any possible or hypothetical cures for radioactive poisoning?

Please submit an answer as soon as possible as it is for a school research project and the deadline approaching fast!

Thank You 222.165.183.45 13:00, 19 January 2007 (UTC)

You probably aren't going to find anyone on Wikipedia willing to do that much work for you. Why don't you start by reading some of the Wikipedia articles in THIS SEARCH and come back with some specifics? Editors on WP are more friendly and helpful when you 'show your work', so to speak, and let us help you fill in the blanks. Also, I took the liberty of fixing the wikimarkup and moving your signature. Hope that was OK.Anchoress 13:09, 19 January 2007 (UTC)

Polonium 210? The isotope of choice if, for example a government or government agency (allegedly) wishes to make an example out of a well-known dissident... --Kurt Shaped Box 13:16, 19 January 2007 (UTC)

Look at the half life of the isotope and take only isotopes with a half life of less than a year and you are on the safe side. If you want to be really sure take alpha emitting substances or even better transuran isotopes which do multiple emissions during the decay path! Most of the stuf is not readily available!--Stone 13:49, 19 January 2007 (UTC)

And for the cure look at the star trek medical advisary hompage, you will get plenty of antiradiation pills from Leonard McCoy or Beverly Crusher.--Stone 13:51, 19 January 2007 (UTC)

Although not a cure per se, see potassium iodide. Laïka 14:08, 19 January 2007 (UTC)

Bone marrow transplant? Though if you're unfortunate enough to be contaminated internally with alpha-emitters, the only real 'cure' is to place a pistol to your own head and pull the trigger whilst you still have the strength to do so. --Kurt Shaped Box 14:36, 19 January 2007 (UTC)

Well then as far as radiation poisioning, the only thing that i know that can cure that is a long visit to a hospital and alot of prayers. sure there are some cures out there but they are not fast enough or probable enough to get you fully cured. once damage is done to your body from radiation its either live or die. I have seen cases where the only thing doctors can do is just watch the patient slowly die. as far as a radioactive isotope try americium (sorry cant spell that one right so someone correct it plz - done — Kieff) in any ways you will find that that element is located in most fire detectors in the house! yes you heard right! you can even pull down your fire dectector and read the back of it and it will state on most of them "this detector contains americium a radioactive isotope". go ahead and check it! also if you want to find out how radiation works try going to www.howstuffworks.com and search for radiation and everything you want to know about it. Maverick423 16:18, 19 January 2007 (UTC)

Remember kids - do not under any circumstances eat the contents of a smoke detector, no matter how tasty they may appear... ;) --Kurt Shaped Box 18:45, 19 January 2007 (UTC)

I saw a TV program a few years back where a kid tried to make a nuclear reactor using smoke detectors and I think it was lithium batteries. I can't remember the details, can anyone else? Theresa Knott | Taste the Korn 00:59, 20 January 2007 (UTC)

Ah here it is - David Hahn. 01:02, 20 January 2007 (UTC)

Radioactivity, radiation poisoning, radioactive decay... We have lots of articles on the subject already, take a look! — Kieff 18:36, 19 January 2007 (UTC)

If the radioactive isotopes happen to be heavy metals, perhaps chelation therapy could be used. StuRat 01:08, 20 January 2007 (UTC)

Could some sort of nanotechnology be developed that can prevent most radiation damage, or rebuild afterward:) What about rewriting someones DNA so they can prevent the damage themselves, although this could be considered unethical for some reason:)Hidden secret 7 13:48, 21 January 2007 (UTC)

I don't think that anything you did to the DNA would affect the body's reaction to radiation - it's about physical cell damage from high energy particles. Imagine that a watermelon represents a cell from somewhere in your body. Pretend that you are The Jackal from "The Day of the Jackal". Blast the melon with a shotgun at close range for an idea of what an alpha particle does to a cell. Use a .22 pistol for a beta particle and a pellet gun for gamma. --Kurt Shaped Box 23:01, 21 January 2007 (UTC)

DNA is also the way it is for a reason. Strengthening it externally somehow would cause "difficulties" in cell division and DNA replication. --Wooty Woot? contribs 23:04, 21 January 2007 (UTC)

Also, remember that mutations in DNA are an important element in evolution. Any species which had unalterable DNA would not evolve and would eventually die out to competitors which did evolve. StuRat 06:38, 22 January 2007 (UTC)

If our DNA didn't mutate, we could do it ourselves and evolve as we wanted:)Hidden secret 7 18:46, 22 January 2007 (UTC)

Arun S. Bagh

what is the name of the sign used just above the Angstroms's short-form "A"

See the second paragraph of Å --bmk 15:43, 19 January 2007 (UTC)

Hydrogen storage and burning

Can hydrogen leak out from the walls of a typical, plastic 500-mL water bottle? Also, is it safe to ignite a bottle-full of hydrogen using a match? --Bowlhover 17:27, 19 January 2007 (UTC)

I have seen this before. it appears that when burned in a bottle all that happens is that the fire crawls up the bottle its a pretty awsome sight! as far as safty is involved well it was performed in a school when i saw it so it might be safe as long as you take proper measures.Maverick423 17:40, 19 January 2007 (UTC)

If the bottle were completely full of hydrogen, the match would extinguish due to a lack of oxygen. I'm not sure I would try this though, due to the chance of finding the right ratio of hydrogen and oxygen, and blowing yourself to smithereens. After all, you are dealing with rocket fuel. If curiosity gets the best of you, I'd be sure to fill the bottle by first filling it with water, then bubbling the hydrogen in to ensure only hydrogen is in the bottle, and always keeping the bottle sealed and/or upside down. I'm not sure about the gas going through the bottle, I'm not sure. You could experiment by weighing the bottle on a sensitive balance, then waiting for a while (overnight) and doing it again. Presumably if hydrogen escapes (or another gas enters) you will see a rise in weight. -anonymous6494 17:43, 19 January 2007 (UTC)

Pressure builds up inside the weak water bottle, bottle bursts, oxygen gets in, boom. -- Consumed Crustacean (talk) 17:54, 19 January 2007 (UTC)

Never attempt such an experiment without observing all the safety procedures which would be followed in a well run school lab, such as eye protection, adequate distance from the thing and maybe bulletproof glass between you and it (see how Mythbusters handles explosions). A small amount of hydrogen is capable of an explosion which would sound like a cannon. I saw/heard/felt such a demo at a chemistry department open house when a balloon about 10" diameter full of hydrogen was ignited, which might have held 2 to 3 liters. It literally shook the room. It probably burned faster than a pop bottle full of hydrogen would. A half liter bottle with an explosive ratio of H2 and air or O2 ignited by a spark would be a different story. The ignition in a plastic bottle probably often occurs with a mixture too rich or lean to be at the peak of the explosive mixture ratio. Beware the temptation to think that if some chemical reaction makes a nice "pop," then bigger will be more satisfying. Remember the Challenger and the Hindenberg. Edison 21:03, 19 January 2007 (UTC)

As Edison notes, be very careful with this sort of experiment. If your bottle contains pure hydrogen, combustion will only occur at the opening of the container, at the point where the hydrogen can mix with available oxygen. The combustion will occur at a fairly moderate rate, and all will be well.

However, if you uncap the container and wait for a while (a short while) then the (denser) oxygen in the air will fall into the bottle and displace some of the rising (less dense) hydrogen gas. The net effect will be to mix the hydrogen with oxygen, resulting in a mixture which will burn rapidly (explosively!) if ignited. In the experiment Edison describes (involving a balloon full of hydrogen gas) hydrogen from the balloon is forcefully and rapidly mixed with air as the balloon bursts, resulting in rapid combustion. I've seen this demo too; it's quite impressive. I recommend using a match or other ignition source attached to a long stick, otherwise the explosion could be deafening.

Over a reasonably short period of time, hydrogen won't leak through the walls of a plastic bottle, however it may escape by following the threads around the bottle's cap. TenOfAllTrades(talk) 02:24, 20 January 2007 (UTC)

Thanks everybody. For my first attempt at burning hydrogen, I'll probably tape the bottle to a wall, light a candle beneath it, and run for cover. I might deliberately add some oxygen to the bottle to make the fire more spectacular.

Don't worry about hydrogen escaping through the bottle's top, because I will add some water and invert it. Also, TenofAllTrades, how long is a reasonable amount of time? A month or two?

By the way, this is not a school lab. That's why I'm asking for the safety precautions here. --Bowlhover 05:01, 20 January 2007 (UTC)

vegetables cooking

What cooks faster at the same tempature, frozen vegetables or raw vegetables?

Raw. They need less energy to cook. — Kieff 18:28, 19 January 2007 (UTC)

Remember, though, that many frozen vegetables sold in the states at least are "pre-cooked", these may "re-heat" quicker than cooking fresh. --Cody.Pope 18:53, 19 January 2007 (UTC)

And even if not, the freezing process breaks down the vegetables. I don't know if that process is enough to counteract the extra time (not much, BTW) it would take for the frozen veggies to catch up to the raw. Anchoress 18:57, 19 January 2007 (UTC)

Tritium oxide

Since tritium is radioactive and tritium oxide is similar to water, would an ice cube of tritium oxide melt itself over time? 66.214.220.134 19:30, 19 January 2007 (UTC)

Not if you keep it cold enough. Tritium has a fairly long half-life, at 12.32 years, and based on that and the decay energy, I'm sure someone can figure out how much warmer than ambient temperature a tritium ice cube would be. What is certain to happen is that the ice cube will decompose over time into helium and oxygen gas as the tritium decays. --Carnildo 20:30, 19 January 2007 (UTC)

The size of the block would be critical, as well. Beyond a certain size, there would be no amount of cooling that could be provided at the surface which would keep the interior frozen, much as the core of the Earth remains molten due to radioactivity (as well as tidal forces). StuRat 01:00, 20 January 2007 (UTC)

Thermal Nuclear Rocket

I am unclear about the last bit at the end of the Nuclear Thermal Rocket article about risks. Do these rockets release fallout at all I would think they do but how much?68.120.226.193 20:26, 19 January 2007 (UTC)

A properly-designed nuclear-thermal engine will release no more fallout than any other nuclear reactor. --Carnildo 20:32, 19 January 2007 (UTC)

Which is to say, "none" for all intents and purposes. --24.147.86.187 00:46, 20 January 2007 (UTC)

So if its where launched from an isolated area fine but one of these rockets fying over a city probabely a bad idea?

Well the biggest worry is that it'll pull a Challenger and spread the core materials over a wide area. Disintegrating rockets can spread debris over a very wide area, and depending on what stage of lift-off it came apart in, it could spread the debris over an area very different from where it took off from. But you could probably minimize these risks in a variety of ways (different types of fuel pellets, containment vessels, plotting very specific trajectories) and make them manageable. The real difficulty is the political will and the public distrust of official statements on radiation matters (the US gov. has a pretty bad track record in this respect), among other things. --24.147.86.187 18:44, 20 January 2007 (UTC)

Would fallout be reduced if the rocket where launched from a high altitude in case of explosion?

fallout would be the same as the rocket would be the same size, but it would spread out over a larger area, and be affected by wind more:)Hidden secret 7 18:00, 21 January 2007 (UTC)

Unless, of course, it was only producing αradiation, which could only travel a short distance from the rocket:( I am not sure what it would produce as I am not a rocket:)Hidden secret 7 18:03, 21 January 2007 (UTC) Thanks for all the answers.68.120.81.177 06:09, 22 January 2007 (UTC)

January 20

What does RCSWI mean?

I have a card from a Psychotherapist that has RCSWI along with Ph.D. and MSW. I know what the latter two mean but I cannot seem to find out what RCSWI means. Can anyone help me?72.153.131.41 01:31, 20 January 2007 (UTC)

Rape Crisis Social Work Intern --CBD 15:34, 20 January 2007 (UTC)

Paracetemol

Is paracetemol completed metabolised by the liver, or does it remain in the body? The Paracetemol#Metabolism section helped a bit though, very sciency :/ Thanks, RHB ^{Talk - Edits} 01:59, 20 January 2007 (UTC)

The vast majority of paracetamol (acetaminophen, for those to the west of the Pond) is indeed metabolized in the liver. About five percent gets excreted in a chemically unchanged form; see [18]. Most of the rest (about 90%) gets combined with glucuronide and sulphate and excreted; another five percent of a typical dose ends up oxidized to benzoquinoneimine: the toxic species in a paracetamol overdose. (The liver can normally detoxify benzoquinoneimine by combining it with glutathione and further matabolizing it; in an overdose the liver's supply of glutathione is depleted, resulting in an accumulation of benzoquinoneimine and toxicity.) TenOfAllTrades(talk) 02:15, 20 January 2007 (UTC)

Accented beats in music

How much louder are the accented beats (on 1 and 3 say) than the other beats in dB?

There is no standard; you should just make them noticed over surrounding, If the note has a marcato accent over it, you should play them louder than surrounding unaccented notes. If it doesn't there still is no standard, however you should not make it that significantly noticeable. X [Mac Davis] (DESK|How's my driving?) 05:36, 20 January 2007 (UTC)

The question doesn't make sense and indicates a basic misunderstanding of the concept of accent. Metric accents ("on 1 and 3 say") are distinguished only by their position in the rhythmic structure and are often softer than other notes. Even dynamic accents, the only kind which are necessarily louder, can be louder by any amount, from the just noticeable difference to the entire dynamic range of the instrument or ensemble. —Keenan Pepper 19:51, 20 January 2007 (UTC)

RF Load

Greetings, I am building a RF Load as a part of engineering sylabus. I want to know why the resistive element is kept in a exponentially tapered housing. Why exponential? How will it vary the resistance in the resistive element? — Preceding unsigned comment added by 203.187.198.33 (talk • contribs)

You dont say what freq you are operating at, but I dont think theres any need to make the housing exponential in shape. (think of Waveguide loads for example -threy arent exponetially varying in dia. However, since the RF energy flows through the dielectric rather than the conductors, any absorbing elements should be placed in this path such that the energy enters them sideways.. ie the load resistors should be wired radially from the centre conductor to the screen. It is prefereable to use many(low inductance) load resistors spread around the circumference of the screen to absorb all the energy. Resistors placed in the cenetral conductor will appaer inductive and will not give a good 'match' to the source. xxxx —The preceding unsigned comment was added by 88.109.209.79 (talk) 02:22, 21 January 2007 (UTC).

Thank you for your swift reply. I understand what you have mentioned. But the question still remains. If you say exponentially tapered housing is not necessary then why all manufacturers use it? I have tried to contact the manufacturers but haven't got any reply yet.

(Cant resist this one) Exp matching sections act as impedance transformers, though why you would need one in a well designed load, I dont really know. Do you have any pics or diagrams of the loads you describe.?--Light current 05:13, 21 January 2007 (UTC)

OTOH, having thought about this, I think if the load resistor was axial in the centre conductor, and the outer shield dia was to taper (conically) from the cable dia down to zero (where the other end of the load resistor is connected), then this would probably give a good match. THis would be because the line imepdance gets lower and lower as the wave travels towards the earthing point due to the changing dimensions.

However, I do not know if any commercially produced loads use this technique. Maybe the very high power water or oil cooled ones do. —The preceding unsigned comment was added by Light current (talk • contribs) 17:26, 21 January 2007 (UTC).

(Moved from my talk) Thanks a lot for that stuff on RF Load. Yes, you are right. Conical tapering is used in high powered Loads that are oil cooled.

--Light current 05:46, 22 January 2007 (UTC)

I vaugely seem to remember some (RF?) components that were shaped like 2 cones joined together at their open ends. THis could hve been for:

• increasing diameter of the both inner and outer (at constant impedance (50R)) to allow for large dia of resistor cf inner of cable.
• decreasing dia of outer towards earth to give decreasing impedance towards the apex of the cone wher the other end of the resistor is terminated.

I cant remember where I ve seen these things! Pictures would be nice. --Light current 16:04, 22 January 2007 (UTC)

Aha! the almost complete answer to the question! [19] --Light current 21:34, 22 January 2007 (UTC)

Thanks for the continued interest. I am not able to get the equations for the tapering? Related to frequency I am sure but how exactly I cannot fathom? I would put snaps of the tapered loading, only I dont how to put pictures. Am a new user so you'll have to help with that too

Hmm. Did you not look at the reference I linked in my last post above? It gives the formulae--Light current 15:49, 23 January 2007 (UTC)

Thanks a lot.. I did overlook the link before but now i got it. Anyway do tell how to put up pictures here for u to see??

Head on collision between atoms and thermodynamic temperature

Ok, so temperature is the average kinetic energy of atoms. What if there are 2 atoms with the exact same speed collide perfectly head on at slow speed (ie. not enough to break the atom or fuse them together), would the atoms stop and appearantly lose kinetic energy? --antilived^{T | C | G} 10:45, 20 January 2007 (UTC)

Nope. If they're capable of reacting chemically, then they might form a chemical bond; two hydrogen atoms will do this, for example. If there's no chemical reaction, then they'll just bounce off each other. If you roll two billiard balls towards one another, you'll see the same phenomenon—the momentum and kinetic energy of the system will both be conserved. TenOfAllTrades(talk) 10:54, 20 January 2007 (UTC)

OK, guess I forgot that the third law applies to atoms is well... :p --antilived^{T | C | G} 11:03, 20 January 2007 (UTC)

To clarify - the temperature of a substance is a measure of the average energy of its atoms or molecules; for an ideal gas, we assume that there are no intermolecular forces and that collisions between one molecule and another and between molecules and the walls of the container are perfectly elastic; with these assumptions, we can use the kinetic theory of gases to determine that the temperature of an ideal gas is proportional to the average kinetic energy of its atoms or molecules. Note that if the gas is not monatomic, some of this kinetic energy will be rotational energy. The assumption of perfectly elastic collisions is required so that the total kinetic energy of the atoms/molecules is conserved in inter-molecular collisions. Note that this is not a consequence of Newton's third law, because Newton's third law also applies to inelastic collisions. We can show experimentally that real gases behave as if they were ideal gases under most conditions, but the ideal gas model does not work at high pressures and low temperatures. Gandalf61 13:42, 20 January 2007 (UTC)

Vocal loading

I show show all the signs of overloaded vocal cords. I have a relatively low pitched voice (for a male), and though I was quite a mumbler when I lived back home, since I've been overseas, I have to clearly pronunciate myself in English, not to mention that I'm speaking another language half the time, one that doesn't give many allowances for "mumbled speech". This causes extra strain on my vocal muscles, even to the extend that I get very tired after a day of simply talking. Another one of the symptoms listed for vocal loading is a limited vocal range. When I was young I had a decent singing voice, I could hit all the notes, even if it wasn't the most beautiful voice to listen to. After puberty my vocal range completely dissapeared and I can no longer sing even easy songs without fading out on slightly high or low parts (becaues I'm already singing at a lower octave).

It's quite frustrating! I try to conciously decrease the volume of my voice, and at times I will even press on my neck while talking in order to reduce the vibrations/slightly decrease the tone of my voice, but that doesn't really do anything at all. Does anyone know of a way I can get beyond this vocal loading? If I could just somehow increase the efficiency of my speech voice, or increase the strength of my vocal muscles without tiring them out. 222.158.163.22 12:15, 20 January 2007 (UTC)

This is a bit of a personal medical question, so we can't really do much for you (see the preamble at the top). But I've had the same problem when I was choir singing. Gargling with salt water helps, but you should see a voice coach to stop doing what you are doing to the chords. Nevertheless, I had to give up choir singing. :( --Zeizmic 13:07, 20 January 2007 (UTC)

From personal experience, I suggest you schedule a consultation with a laryngologist (or ENT, i.e. ear, nose, and throat specialist), a physician who will examine your vocal cords for structural damage and other abnormalities. Ruling out these, you may be referred to a speech therapist who will evaluate how you use your voice and provide remedial exercises. In my case, a course of this sort of therapy succeeded in resolving an actual case of vocal cord nodules that might otherwise have been treated by surgery - and the latter might not have prevented recurrence anyway. Be sure to mention your particular vocal activity (everyday as well as singing) to the doctor and therapist. -- Deborahjay 16:03, 20 January 2007 (UTC)

Further: consider that like any medical condition that can become more serious, catching it in its early stages improves your chances for a less-invasive, more successful treatment. A related therapy worth investigating is the Alexander technique, though this is along the lines of treatment and not a substitute for diagnosis. Otherwise, as a vocalist you may benefit from voice coaching, particularly breathing techniques that will help you learn to produce sound more effectively without undue strain on your vocal cords. -- Deborahjay 17:16, 20 January 2007 (UTC)

Sorry, I'm not a vocalist, I didn't mean to put across that message. And it's nothing serious, really. If I speak to someone from my hometown my voice naturally relaxes a level (and I start mumbling again), and I feel no stress in my vocal cords while talking any more. It's been 3 years and it hasn't gotten any worse or better (it's not painful or anything, I just can't belt at all), so I was just wondering if there was any way I could personally train my voice, without resorting to something like therapy. 222.158.23.50 04:48, 21 January 2007 (UTC)

Arun arun arun

1. what is the fullform of AAA used in dry batt
2. what are the names of black and white keys of piano or synthesizer?
3. what is the name of suicide by cutting wrist?

— Preceding unsigned comment added by 221.134.58.145 (talk • contribs)

1) I don't think it means anything. There are C and D batteries, as well as many others.

2) Major scale is the closest answer I can give you

3) Exsanguination, I think. — Kieff 13:22, 20 January 2007 (UTC)

1) I'm guessing one A stands for alkaline. -Obli (Talk)^? 13:28, 20 January 2007 (UTC)

No, it doesn't. AAA refers to the size only. See battery (electricity). They are not necessarily alkaline batteries. The keys on a piano keyboard don't have names, but the notes they play do. See musical keyboard.--Shantavira 14:04, 20 January 2007 (UTC)

The words "Naturals" and "Accidentals" are used for the white and black keys respectively. See Musical keyboard. I found the article by looking for Key, and then, under "Music" heading, for Key (instrument), and thence to "See also musical keyboard". --Seejyb 21:23, 20 January 2007 (UTC)

Well, no, actually: for example, a C-flat would be played on a white key (B), a C-double-sharp on a white key (D), and both are accidentals, given, say, a key of E-flat for the C-flat, and D-sharp minor for the C-double-sharp. I have fixed the musical keyboard article accordingly. White keys and black keys are absolutely not called "naturals" and "accidentals", at least not by any trained musician. Antandrus (talk) 02:47, 21 January 2007 (UTC)

They are supposed to be natural and accidental based on C Major. --Kainaw ^(talk) 12:37, 21 January 2007 (UTC)

As a group, the white keys are known as "the white keys", and as a group, the black keys are known as "the black keys". Individual keys do have individual names (I must respectfully disagree with Shantavira about this). When I touch "middle C" on a piano, I am touching a physical object. The note made by depressing that key is called "C". JackofOz 03:56, 22 January 2007 (UTC)

Metal identification and care

I recently moved into a new home, with a gas stove included, and would like help in identifying the "splash plate" underneath the stove burners. This is designed to be removable so it can be cleaned, which I've done. Initially the metal was completely black. This would have led me to think it was cast iron, except that it appears to be too light and didn't show a speck of rust, even when soaked in water. Here comes the odd part, merely soaking it in water changed the color from black to roughly the color of steel. Now this seems quite strange to me, I've never heard of a metal losing it's patina simply by soaking it in water. I didn't add any dishwashing detergent, but some might have gotten on it from when I did some dishes above the soaking plate, by hand. At any rate, I was quite happy, it looked like I only needed to soak the metal in water to get rid of that jet black coating. But, then when I pulled the plate out of the water and left it to dry, it first developed a greyish-blue patina, then turned jet black again, within a day. So much for that approach.

My first question is what metal I have here. I don't think it's steel or iron, as noted above. Aluminum (aluminium, for you Brits) is lightweight, but I believe it oxidizes to form white spots. Magnesium is also lightweight, but flammable, so I doubt if they would use that. Chromium, or at least a chrome plating, would be shinier, I think. I'm thinking perhaps it's tin or nickel plating. Does this behavior sound correct for either ?

My next question is how to keep it from turning that horrid black color. The previous resident just wrapped it in aluminum foil, and I may end up doing the same unless anybody has any other ideas. The oven/stove combo is made by Electrolux, it's brand is Tappan, and it's model is Meadowbrook, if that helps. I'm guessing it's pretty old, perhaps as old as the 1920's, as that's when the house was built. StuRat 19:01, 20 January 2007 (UTC)

Is it magnetic? Could the "patina" actually be some kind of coating? Im think the colour may have something to do with the surface being microscopically rough and the water filling in the holes so to speak. Although come to think of it, that usually makes a material become darker when wet. Theresa Knott | Taste the Korn 09:10, 21 January 2007 (UTC)

A magnet does stick to it, yes, so it's likely steel underneath. I've concluded it's got a thick layer of chrome plating, too. It doesn't have the shiny look I associate with chrome plating, which threw me off at first, but chrome plating apparently loses that shininess with time and heat, as per the next response. The lack of rust would indicate that the chrome plating hasn't yet eroded through, however. StuRat 06:32, 22 January 2007 (UTC)

I'm guessing it's probably thin steel with a Teflon coating, although I've never noticed a color change from soaking those in water.

[For electric stoves, which you don't have, and which I bring up only because I'm an idiot who wasn't paying attention,] You can buy replacement stove pans in many stores, of a universal design that (in the U.S., anyway) fits most "ordinary" [electric] stove burners. I generally see these in two styles: chrome-plated steel and Teflon-coated. The chrome-plated ones wear out after a while: the chrome pits through, the steel begins to rust, they get less and less shiny and more and more difficult to clean. Presumably the Teflon-coated ones are supposed to be "better" at this. But I believe (unsourced, original-research opinion alert:) that this is fallacious: for one thing, Teflon coatings eventually wear off, too, and for another, black is a horrible color for stove pans. Since it absorbs heat, the pans get wickedly hot, and any spilled food just gets baked on more strongly.

I've decided that the right approach to [electric] stove-pan cleanliness is to (a) use the chrome-plated ones, which reflect heat instead of absorbing it and are therefore likely to be more efficient to boot, and (b) simply replace them every year or two when they start getting dingy-looking -- they're really not that expensive. (You spend much more time than they're worth trying to clean them when they're corroded, or painstakingly wrapping aluminum foil over them, which of course looks dreadfully tacky.)

—Steve Summit (talk) 16:06, 21 January 2007 (UTC) [edited 00:43, 23 January 2007 (UTC)]

I would guess I have the chrome plated steel. I will look for replacement parts. Each plate is for two burners, is this standard ? I agree that the aluminum foil looked tacky, that's why I removed it (the previous resident had left it that way). BTW, why don't they use stainless steel ? Doesn't that hold up to the high temps ? StuRat 06:21, 22 January 2007 (UTC)

I'm sorry, I wasn't thinking, and I didn't pay attention to the fact that you said you had a gas stove, and consequently my answer is rubbish. The "universal" pans I described are for electric stoves; gas stoves don't have them. (And they're for individual burners, never two-burner combinations.) —Steve Summit (talk) 00:43, 23 January 2007 (UTC)

Sleep and long-term memory

I've noticed something disappointing and strange about my memory. I have always done better than nearly anyone else in my classes in history. On tests covering a week or two of material, I almost always end up on top gradewise. But when I get to exams, although I study as much as--and probably more than--most people, my average is usually far worse in relation to other students than is my short-term test average. I also notice that I have trouble remembering facts from the last year, whereas some students who didn't do as well in last year's class remember dates, names, and similar info from that class now better than I. This is really irritating, so I've spent some time thinking about possible causes. One is that I'm just taking more classes at once than most of my friends and therefore focusing on too much at once, so my memory is, in a way, spread thin. Another idea that came to mind, and one I'd like to verify, is that because I have so much work and stay up so late getting it done, my lack of sleep (usually 4 or less hours of sleep per night) is affecting my long-term memory. I don't know what made me think this. Is that at all a plausible idea? I can't think of anything else. I don't smoke pot often or anything, and I usually have a very good memory and have, for instance, been able to memorize a song's lyrics after just a listen or two and not forget them for many years. Any other possible explanations? Any suggestions? Thanks a lot. Sashafklein 19:28, 20 January 2007 (UTC)

Yes, this is a very plausible idea. Sleep is the time for memories and other information to be consolidated within the brain, so getting half the recommend amount of sleep (eight hours) can't be good for your long-term memory. Please, do yourself a big favor and take a nap right now. :) Vranak

I believe what we memorize (or, more specifically, what goes into our readily accessible "high priority memory") is decided by how important we think something is. Those song lyrics are important to you and history is probably not. You may be able to trick your brain into giving history a higher priority by putting history facts to the tunes of songs you like. Another common method is to repeatedly expose yourself to the thing you want to memorize, as with flash cards. Be sure to repeat this throughout the year to keep the memories "fresh", otherwise your brain decides "I haven't used that bit of info for a while, so it can't be all that important, let's push that memory way into the back room". StuRat 20:58, 20 January 2007 (UTC)

Both of these suggestions are mentioned in the article on Long-term memory (if you remember for a week that is long-term memory). It looks as if StuRat's advice on repetition should work wonders for you - the article has a link to Spaced repetition - and Vranak's suggestion is echoed in the reference to Sleep and learning. So there, the thoughts of two respected editors and all those linked articles seems like the way to go. --Seejyb 21:42, 20 January 2007 (UTC)

I'm going to stick with sleep, because I really do like history, and I'd like to hope my brain doesn't disagree with me. I guess I'll just try to sleep more. Sashafklein 21:43, 20 January 2007 (UTC)

I have a similar but different problem. I forget everything after a long deep sleep whenever I have not had enough sleep and my mind and body begin to shut down by practically putting me in a comma. When I wake up I can not seem to remember the project I was working on or if I do where exactly I left off, especially any completion plans I had for when I woke up. Unless I remember to write down everything before I go to sleep (which the overpowering need for immediate sleep may prevent) I'm totally lost when I wake up as to what I need to do. Keeping constant notes of what I am doing is the only guard against complete and total loss against waking up with no idea of whatever has gone before. [BTW - sometimes I even forget I have made any notes and do not even look for them when I wake up.] -- Barringa 03:34, 21 January 2007 (UTC)

I don't think that's specific to sleep, if you took an 8 hour break without sleeping you would likely also forget where you were when you went back to work. I have the same problem, so either try to find a good "stopping point" (where one task was completed and the next not yet started) or would have to leave myself detailed notes on what parts of the task were done and what parts were not. StuRat 04:40, 21 January 2007 (UTC)

Unfortunately when the need for sleep comes on me its is sudden or instant. Since I multiplex tasks its rare when I have no tasks I'm in the middle of and when this rare occurance does happen its usually close to the time when I've woken up and completed every task and not lilkely to be "called" back to sleep. Also my waking hour vary to such an extreme degree there is not way of projecting. -- Barringa 08:13, 22 January 2007 (UTC)

Are you elderly by any chance ? Those sleep patterns are identical to my father's, he falls asleep mid-conversation at random times of the day. (Small children do the same thing, but you're obviously not a small child.) I think I'll post a question on this at the bottom of this question. StuRat 22:58, 23 January 2007 (UTC)

This is a natural memory trait common among actors. I can read a script a couple time and recite my lines rather well for a few days. Ask me lines from a play I was in last month and I'd be lucky to remember anything from it. I've often been told that if you have to memorize lines, you'll always have trouble. If you have an actor's memory, you'll do well. --Kainaw ^(talk) 12:42, 21 January 2007 (UTC)

If someone read a few lines of the older play, could you then remember what was after that, and after that &c :)Hidden secret 7 18:48, 22 January 2007 (UTC)

No. When the play is flushed it is gone. (I can't avoid dropping names in the next comment, so please forgive.) It often happens during filming, but it usually hard to tell. Sam Jackson had to recite the same line three times in Pulp Fiction (the Bible scripture). Each time he said it with slightly different words. I asked him about it and he said that he is constantly asked to recite that line and he can't remember it, so he asks the fans to recite it to him "just for fun". --Kainaw ^(talk) 04:41, 23 January 2007 (UTC)

Sleep patterns in the elderly

I've noticed that some of the elderly fall asleep at seemingly random times, when engaged in activities which would keep a middle-aged person awake, like talking or riding in a car. This seems like a mild form of narcolepsy. It's not total narcolepsy in that they still have some control over when they go to sleep, but far less than younger people do. For example, a middle-aged person might start feeling tired but be able to finish their current tasks, get ready for bed, and then go to bed. This process could be stretched over several hours if they have a lot to do. With at least some of the elderly, however, they have a few minutes at best between when they first feel tired and fall asleep, not enough time to finish their current task, get ready for bed, and physically get into bed. They frequently fall asleep where they are sitting, as a result. By contrast, someone with narcolpesy may fall asleep with no warning at all. The elderly also seem to have more shallow sleep and wake up often. So, the question is, what causes these changes in sleep patterns among the elderly ? StuRat 22:58, 23 January 2007 (UTC)

Why do we steadily lose high frequency hearing ?

I know that it happens, from the teens onward, but my question is why ? If there is enough of an evolutionary advantage for high frequency hearing to have developed in kids, why is it not also as important for adults ? At first I was thinking this high frequency hearing loss was due to listening to loud music, but I believe I may have been wrong on that. Therefore, I need to find another explanation. If it happened only in the elderly (specifically, after the end of the reproductive years), it would be easier for me to understand. StuRat 20:45, 20 January 2007 (UTC)

I expect the higher frequency hairs in the cochlea are damaged more readily. Right now we think it happens because of cumulative damage from hearing any noise, or any noise above 70 dBa (100 was the old number). X [Mac Davis] (DESK|How's my driving?) 21:14, 20 January 2007 (UTC)

Possibly this was all lies, but my teacher told me, a long time ago, it was because the eardrum became less taut over time. As to evolutionary advantage: if hearing is going to lose a certain amount of range, and a certain range is required, I would think it would make sense for children to have unnecessarily acute hearing so that when they lose the higher ranges they are left with enough. Ie. if you need to be able to hear as high as 'b', and you're going to lose 'x', children should be able to hear 'b +x'. The first part of this answer comes from unreliable teachers, and the last part is original research ('what I think'), so don't rely on it or anything. Skittle 22:55, 20 January 2007 (UTC)

I find Mac Davis's explanation very convincing. Hair cells in your cochlea could be to blame. --Kjoonlee 04:00, 21 January 2007 (UTC)

Atoms & subatomic particles

Can atoms and/or sub atomic particle be viewed under a microscope? I have been trying to get this info for years - ever since I learned about atoms & subatomic particles in elementary school, but have, somehow, not been able to find it.

Thanks, Janet Akpobome

Images of structures at atomic level can be generated using devices such as a Scanning tunneling microscope and an Atomic force microscope. Remember this is not "seeing under a microscope", as we normally think of. If you read the "See also" articles at the bottom of those pages, you would get a wider picture of this field of Nanotechnology. --Seejyb 22:09, 20 January 2007 (UTC)

The phenomenon of "seeing" an object is a result of many photons being emitted from an object's constituent atoms and entering the eye to produce an image. The concept of sight is somewhat difficult to define when the size of the object is comparable to the wavelength of the light being used to see the object. --bmk

Generally speaking, under an optical microscope you cannot differentiate individual atoms, much less subatomic particles. --24.147.86.187 23:33, 20 January 2007 (UTC)

I did find the Gold Foil experiment and the Oil-drop experiment interesting when I was taking a physics course. Those have some relevance with seeing electrons (although you can't see them with a microscope, you can still prove their existance). --Wirbelwindヴィルヴェルヴィント (talk) 08:38, 21 January 2007 (UTC)

An atomic force microscope feels the atoms in much the same way that a blind person feels the dots of braille. I can't think of an analogy for the scanning tunneling microscope :-( Theresa Knott | Taste the Korn 09:03, 21 January 2007 (UTC)

Also see Field ion microscope (and the "See alsos" on that page).

Atlant 00:40, 22 January 2007 (UTC)

Number of farads per square foot or pound...?

What is the largest capacitor commercially available and what portion of a square foot does in occupy or in the alternative how much does it weight? Also if you know the cost, that too. -- 71.100.10.48 22:30, 20 January 2007 (UTC)

Supercapacitors can be over 2600 farads

Even though I did not find this claim documented in the article that was not the question. 2600 Farads can be achieved using 2600,000,000 1 microfarad capacitors. The question is the largest number of farads per square foot or pound. BTW - please provide your user name or IP when responding. -- 71.100.10.48 03:16, 21 January 2007 (UTC)

Chasing links from Supercapacitor to "Maxwell" to their corporate web site to their product page

[20], I get 3.81 Wh/Kg for the big ones. -Arch dude 18:11, 21 January 2007 (UTC)

The total capacitance in Farads is not the be-all and end-all with respect to energy storage in capacitors. The voltage rating is critically important, since the energy stored varies as the square of the voltage. A 1 Farad 20 volt capacitor would store

$E_{\mathrm {stored} }={1 \over 2}CV^{2}Joules$

=200 Joules of eneregy. A .5 Farad 40 volt capacitor would store 400 Joules. Keeping the dielectric material the same and the area of the capacitor plates the same, doubling the thickness would in general double the voltage withstand ability of the device, while cutting the capacitance in half, per :$C\approx {\frac {\varepsilon A}{d}};A\gg d^{2}$. As above this would double the energy stored. If the dielectric were made 10 times as thick, the voltage rating would in general go to 200 volts, the capacitance would decrease to 0.1 Farad, and the energy stored would increase to 2000 Joules. Edison 15:52, 22 January 2007 (UTC)

Heat

what is heat? —The preceding unsigned comment was added by 68.74.79.7 (talk • contribs).

The article on Heat may be a good place to start. You can search for topics yourself using the seach box on the left side of the screen. Feel free to ask another question if the article is not clear or you still have questions. Thanks and best wishes, --TeaDrinker 01:56, 21 January 2007 (UTC)

Energy in transit according to the article listed above. This sounds about right to me. Vranak

In short though, it's just energy. I'm not even sure I agree with the transit part. --Wirbelwindヴィルヴェルヴィント (talk) 08:27, 21 January 2007 (UTC)

First, remember e=mc²; matter is energy. Second, one does not feel heat unless it is in transit into them. Vranak

I guess an important conceptual detail is that heat and temperature are different, though related, quantities. Heat is the energy, and temperature is the average energy per molecule (often times, the "average kinetic energy of the molecules of a gas"). In this way, something small (with few molecules) can have a very high temperature, but not have much stored heat energy. A good example is "flying sparks," which glow white-hot with temperatures probably in the thousands of degrees Celsius, but with so little actual heat that they are harmless to most things they land on (keyword - most :) Nimur 21:25, 21 January 2007 (UTC)

water body

If an average human body was completely ridded of bones, organs, muscles, etc, how much water could the empty body hold? assuming it was filled until it was firm, not until it popped. —The preceding unsigned comment was added by 129.123.214.24 (talk) 04:13, 21 January 2007 (UTC).

Approximately the same weight in water as the person weighed before their unfortunate run-in with you. StuRat 04:26, 21 January 2007 (UTC)

Minus the weight of the skin, which takes up 13% of the body weight (http://hypertextbook.com/facts/2001/IgorFridman.shtml). --Bowlhover 05:00, 21 January 2007 (UTC)

So... What would be the average density of the human body? --Kjoonlee 05:41, 21 January 2007 (UTC)

And the average volume? --Kjoonlee 05:42, 21 January 2007 (UTC)

Average density of the human body is about 1.1g per cm cubed, or slightly higher then that of water. Which is why if you are in a pool and exhale as much as you can you will typically sink slowly. So the average volume is just under one cm cubed for every gram of weight, or just under ten cm cubed for every kilogram. Vespine 06:08, 21 January 2007 (UTC)

Surely you mean 1000 cm^3 for every kilogram. --Wirbelwindヴィルヴェルヴィント (talk) 08:21, 21 January 2007 (UTC)

Surely I do, 10cm x 10cm x 10 cm is 1000 cm^3, I had 10 centimeters cubed rather then 1000 cubed centimeters in my head... Vespine 23:37, 21 January 2007 (UTC)

gallon challenge

is it possible to drink a gallon of milk within half an hour without throwing up? —The preceding unsigned comment was added by 129.123.214.24 (talk) 04:13, 21 January 2007 (UTC).

... or yogurt? Yes! -- Barringa 04:17, 21 January 2007 (UTC)

Don't know about milk, but you might want to read Water intoxication, which states that downing as little as 3 litres (0.79 gal) in a single sitting may prove fatal, as one woman has already proven recently. Clarityfiend 05:55, 21 January 2007 (UTC)

I believe this is extremely dangerous to do, as water intoxication will definitely set in and you will become sick. Throwing up is not an issue when either you die or need to be admitted to the ER. X [Mac Davis] (DESK|How's my driving?) 07:22, 21 January 2007 (UTC)

In general, remember that throwing up in these situations is good. Your body is trying to protect itself, and it normally does a pretty good job. Any time you try to "trick" your body, for example by trying to avoid throwing up even as you're downing excessive amounts of some toxic substance, is a time you've got to be worried that you might be tricking yourself right into your grave. (All too many college students belatedly rediscover this fact after extreme episodes of binge drinking.) —Steve Summit (talk) 15:53, 21 January 2007 (UTC)

I don't know about a gallon of milk, but I frequently consume a half-gallon jug with my meals in about 15-20 minutes. (Of course, I don't drink the milk all at once. I eat some, sip some milk, eat some more, etc.) — Michael J 18:48, 21 January 2007 (UTC)

Each human has their own unique tolerance to lactose levels. The amount you can consume without indigestion (or toxicity) will vary based on your previous diet, your health, and perhaps even genetic predisposition. You might try to eat a cup of yogurt to aid your digestion: though you will have more lactose, commercial yogurt often contains Lactobacillus acidophilus bacteria to assist your natural digestion of dairy. Of course, avoid self-harm by exercising common-sense limits. Nimur 21:30, 21 January 2007 (UTC)

After a couple of decades of eating cereal every day, I finally developed a strong aversion to all milk products. After about a year off dairy, I started eating ice cream again. After two, I'm back to a fair amount of butter and milk. So it seems your body can get overloaded with lactose over a long enough time, but it will 'reset' after a reasonable break. Vranak

The osmolality of milk ranges around 480 to 590 mosm/kg. It's not at all the same as drinking water. - Nunh-huh 22:47, 21 January 2007 (UTC)

It can be done - 2 kids on my swim team did. -- Sturgeonman 18:45, 23 January 2007 (UTC)

Supercapacitor research...?

I'm looking for any program that sponsors research into the use of supercapacitors for use as:

1.) an energy storage device for vehicles under 750 watts, and

2.) for capture and storage of random power generated by ultra high voltage sources, i.e, static electricity and in particular lightning.

-- Barringa 04:15, 21 January 2007 (UTC)

A related field is Photovoltaics or solar power. In a sense, most solar-powered vehicles use a battery (or capacitor) bank to store charge. To my knowledge, most of these are necessarily less than 750 Watts, because solar panels (on today's market) are usually less than this range (that would be between 5 to 10 industrial-strength panels, which would totally cover a very large vehicle). Consider the Stanford University Solar Car ? —The preceding unsigned comment was added by Nimur (talk • contribs) 21:34, 21 January 2007 (UTC).

The potential of solar power is 1000 watts per square meter. With sufficiently large value capacitors or batteries solar panels need not be on the vehicle but instead used to feed the grid from many locations. The advantage of capacitors for vehicles is in regenerative braking and other high power, short time span recharge instances where batteries are unable to recharge or discharge at the same rate or power level for the duration that capacitors can. This advantage also applies to capture of lightning and static electricity. Until solar panels are 100% efficient keep them on the farm. ☺ Barringa 08:46, 22 January 2007 (UTC)

It's not strictly related to your question, but you may be interested in the media buzz surrounding EEStor. --Robert Merkel 11:15, 24 January 2007 (UTC)

Length of an hour...?

Why is an hour 1/24th of a day and night and how long would a Moon or Mars hour be? -- Barringa 04:21, 21 January 2007 (UTC)

The article on hour contains an extensive history of the hour which contains answers to your question. The article on Mars states that the Martian day lasts about 1.028 Earth days - I'll let you do the units. The Moon is a little more complicated since it is orbiting the Earth. However, (correct me if I'm wrong), since the Moon is tidally locked with the earth, the sun should transit the lunar sky with the same period as the earth, so I would say a lunar hour is the same as an Earth hour. --bmk

The Moon is tidally locked, which means its day is the same length as its orbital period. They're both 27.3 Earth days, according to the Moon article. --Bowlhover 04:54, 21 January 2007 (UTC)

A day is (basically) a physical phenomenon: an earth day would be the same even if there were no humans. (to a close approximation.) An hour is a social phenomenon: 1/24 of a day, by social convention. The correct definition of "hour" for Mars was the subject of a lot of debate a few years back, and until we have a Mars colony, the debate is acedemic: the colonists will decide. For the moon, so far we have used the earth hour. The Lunar "day" is too long to use as a sleep-wake cycle, so moon colonists will almost certainly use Earth days and earth hours.

Osmosis

I was given the task of:

"Design an investigation to find out the effect of different concentrations of salt solution on the turgidity of cylinders of potato"

But how on earth can I test the "turgidity" of the potato cylinders? Thanks —The preceding unsigned comment was added by 203.198.23.69 (talk) 07:25, 21 January 2007 (UTC).

Assuming you look up what "turgidity" is, it seems that you need to setup an experiment to consistently measure each of the potato cylinders you put in various salt solutions. --Porqin 07:45, 21 January 2007 (UTC)

This is a common school experiment. See our article on osmosis and for example:

• http://cyro.cs-territories.com/gcse_biology/bioosmpot.html
• http://en.wikibooks.org/wiki/Transwiki:Osmosis_demonstration
• http://sps.k12.ar.us/massengale/potato_osmosis_bi_lab.htm
• http://www.echeat.com/essay.php?t=28497

Note that teachers have access to the internet too so read the essays above, understand them, then write you own report. Do not copy and paste from them. Theresa Knott | Taste the Korn 08:51, 21 January 2007 (UTC)

Better yet, read them, do the experiment, write your own report, and cite the papers in your report. This tells the teacher that you did some literature search, which is an important part of any science project or experiment. It's not cheating, but rather the opposite. If you can make one of the experiments better (cheaper, easier, more precise, more repeatable) then you have a GREAT report: just state openly that you started with an expetrimental design you found in your literature search and what you did to make it better. -Arch dude 17:42, 21 January 2007 (UTC)

Nuclear

I have some questions about some ideas I have on how it could be possible to make a "sun" here on Earth. I would like to talk to someone live if possible because i don't know the lingo or have the mathmatical skills to work out the problems on my own?Evilsmurf213 09:58, 21 January 2007 (UTC)

Well, you can't literally make a "sun" on Earth, because the Sun is a vast ball of hot plasma many, many times larger than the Earth. It is possible to replicate, on a smaller scale, some of the thermonuclear reactions that power the sun. This happens in an uncontrolled fashion in a thermonuclear bomb. Doing it in a controlled and safe way is very difficult, and doing it in a useful way that generates more power than you put into the reaction in the first place is very, very difficult. To get an idea of the technical difficulties involved, see our excellent article on fusion power. Gandalf61 10:17, 21 January 2007 (UTC)

They did it in Spider Man 2 with tritium fusion. Tritium is a hydrogen isotope. How the movie presented it would be quite impossible, however the concept of a sun-like ball of plasma may be possible. Fusion power can give you more information on that. X [Mac Davis] (DESK|How's my driving?) 10:37, 21 January 2007 (UTC)

Today's best-guess implementations focus on magnetic confinement of the plasmas. Great effort has been spent on the theoretical requirements of such a machine; but many features such as controlling the confinement, the extreme environment (pressure, heat, high-currents), and massive electric currents and magnetic fields make this approach infeasible with 2007 technology. Nimur 21:40, 21 January 2007 (UTC)

Current technology can sustain a controlled fusion reaction for short periods. The Joint European Torus can achieve it for a few seconds, and ITER (under construction) is designed to generate 500 MW of fusion power for up to 500 seconds. What seems to be beyond current technology is to do this in an energy-efficient way, so that you can draw significantly more power from the reaction that you put into it. Gandalf61 00:03, 22 January 2007 (UTC)

The rusting of Iron compunds

Hello there,

I can not find anywhere the answer to the following question I came over in some past exam papers. Why does a tin-plated iron, when it is scratched at a certain point and the iron is exposed, rust at that point? But, why does a zinc-plated iron that is scratched hardly get any rusting?

Thank you —The preceding unsigned comment was added by 198.54.202.250 (talk) 10:17, 21 January 2007 (UTC).

It might have to do with how zinc has a lower reduction potential than iron. As a result, zinc oxidizes more easily than iron, and thus oxidizing agents will oxidize the zinc first, slowing down the oxidizing of the iron. On the other hand, tin has a higher reduction potential than iron, so the iron will get oxidized first. --Spoon! 12:29, 21 January 2007 (UTC)

See Galvanic anode . Tbeatty 15:03, 21 January 2007 (UTC)

Would the same apply to why rather use alluminium rivets two join two pieces of iron than copper rivets?

Copper is also very soft and malleable, so I don't know if I would trust it in a load-bearing rivet. Though aluminum is light-weight, it is significantly stronger (especially in the form of an industrial alloy). Nimur 21:42, 21 January 2007 (UTC)

Boltzmann distribution

I'm confused by the pages relating to the boltzmann distribution. Can someone clarify what the assumptions are in the model that is used as a basis for the distribution. (I thought it was that each energy state is equally likely and each distinct energy state is counted once?)87.102.44.44 12:41, 21 January 2007 (UTC)

science project question

i have made a fire alarm based on the priciple of the expansion of a bi metallic strip , i was wondering if i could make a smoke alarm out of it because you have to hold a candle under the bi mettalic strip for this to work(the one i made and i think it kinda stupid)212.72.15.225 15:09, 21 January 2007 (UTC)

Before we proceed, does your simple fire alarm work? If so, excellent! As a first step, something that actually works (even if it's not perfect, and even if it seems a little "stupid") is much, much more important than a theoretically better design that, however, does not work.

Smoke alarms are quite a bit trickier than heat detectors. Many of the real ones are based on an exotic radioactive reaction which is obviously out of the question for a school science project. However, another (simpler) kind of smoke detector works based on the smoke particles interfering with a beam of light. You can read much more about real smoke alarms in our smoke detector article.

You might be able to build a simple optical (light-based) smoke detector, using a light source and a photodetector. You can get a simple photodetector kit; they're another popular science project. You would want to arrange a photodetector and a light source on opposite ends of a mostly closed box. Then, you would want to adjust the photodetector so that it's very sensitive, so that it can barely decide whether to be "on" or "off". Then, you might be able to get it to detect smoke blown into the box, since the smoke would scatter some of the light and keep it from hitting the photodetector. Or, you could arrange it so that the light source normally did not shine directly on the photodetector, but the smoke caused some of the light to scatter and hit the photodetector. (That's evidently how the real ones work.)

In either case, it would probably have to be pretty thick smoke, and I don't know how you'd actually go about generating that smoke for testing, but it might work. (Ask for some help here: it would be really ironic if you accidentally started a fire and burned your house down while trying to generate smoke to test your home-made smoke detector with.) Good luck! —Steve Summit (talk) 15:40, 21 January 2007 (UTC)

Expanding on Steve Summit's thoughts:

• Photoelectric detectors don't look "through" the smoke and expect the smoke to dim the passing light; this wouldn't be sensitive enough. Instead, they shine the light through empty space and the detector looks in at the passing light beam from the side. When no smoke is present, the light passes by invisibly and no light is scattered towards the detector. But when smoke is present, the smoke particles and the Tyndall effect cause some of the light to be scattered back towards the detector. Designed carefully, the detector won't see very much light at all when there's no smoke present and quite a bit when smoke is present.

• But the real key to making a sufficiently-sensitive detector that doesn't care about slight changes in light level and slight electrical changes in the circuit is probably to use a pulsing light source and to amplify those variations in light seen by the phototransistor and maybe even synchronously detect the variations in light intensity. That is, use an LED as your light source and drive it from an oscillator that makes it flash at a certain frequency. Then design the amplifier to amplify just that frequency and (maybe) watch for fluctuations that are exactly timed with your pulsing light source.

• Also, you can get aerosol cans of "test smoke"; local fire departments use this stuff to test smoke detectors and they can probably tell you where to get it. If you tell them about your school project, they might even give you a can or two.

Atlant 01:06, 22 January 2007 (UTC)

Wouldn't it be easier just have two phototransistor pointing at slightly different places, one visible to reflection of the LED when there's smoke while the other doesn't and just use an opamp to compare the two signals? Or something like a PICAXE to compare and sound the alarm using a simple programme? --antilived^{T | C | G} 02:53, 22 January 2007 (UTC)

hmm i got ur ideas , will do just that and ill try and fix a spraying device that will get acttivated along with the fire alarm to put off the fire

thanks 212.72.19.74 11:11, 22 January 2007 (UTC)

Meteor (?) near Geneva

This afternoon, around 2 PM local time, I saw what looked like a meteor while walking just east of Saint-Genis, France, just over the border from Geneva, Switzerland. It was south of me, moving roughly east-northeast. There were actually three distinct objects, all very bright and moving near each other, easily visible despite it being daytime. They looked kind of like the pictures of fragments of the Space Shuttle Columbia disaster (although they didn't leave trails), but there was nothing else visible in the sky to imply that it was debris from any kind of accident. Is there any news anywhere about what this might have been? If a meteor, how large and close would it have to be to be visible in the daytime like that? References preferred, but speculation is ok provided it's more educated speculated than I could make. ;) -- SCZenz 17:30, 21 January 2007 (UTC)

I saw something just like that over east kent a few months ago:) At the time I thought it could be a crashing aeroplane, or a UFO:) There are lots of things falling all the time, and of course something very small but close would appear brighter than something huge but far away:( You could ask at your local airport, see if they saw it too:)Hidden secret 7 17:50, 21 January 2007 (UTC)

It was likely very close—it was moving quite fast, and I certainly could believe it went just over the mountains, but obviously I didn't really have the proper reference points to judge. But I didn't think meteors made it to low altitude very often; it would still have to have been large at first. -- SCZenz 18:01, 21 January 2007 (UTC)

I have no clue what you saw, but what amused me was the "just over the border from Geneva" part. It's almost 280km from Geneva to Saint-Genis! You must come from a country where huge distances are the norm. ---Sluzzelin 21:15, 21 January 2007 (UTC)

Oops, I had the wrong Saint-Genis. It should have been [Saint-Genis-Pouilly]. -- SCZenz 14:39, 22 January 2007 (UTC)

I suspect it was a meteor that split into 3 parts, and was much farther away then you think. They probably did burn up in the atmosphere, as most do, after they went out of view. StuRat 05:58, 22 January 2007 (UTC)

Probably space junk! Most meteors arrive at very steep angles. It's a matter of probability: if you take pot-shots at a sphere, you'll tend to hit the "center," and only very few impacts will occur at the "outer edge." On the other hand, most manmade space junk is falling out of orbit and arriving with a nearly horizontal trajectory.--128.95.172.173 02:01, 24 January 2007 (UTC)

Speed of light and Relativity

I am a class 10 student so if i say anything wrong don't get cross

from what i understand Einstein's law of relativity says that nothing can travel faster than light.. it says something like if something approaches the speed of light, its mass will become infinite so it will take infinite energy to take it close to the speed of light...

^^ If I am wrong please correct me.

however, in the article http://en.wikipedia.org/wiki/Lightspeed (Speed of light) it says that:

"The blue glow in a nuclear reactor is Cherenkov radiation, emitted as a result of electrons travelling faster than the speed of light in water" - it is basically saying that electrons travel faster than the speed of light. my question is that since electrons are travelling faster than the speed of light (as mentioned by the article) isn't this a violation of Einstein's law or is the article wrong? Could you please explain in detail.. thanx

~~ MasterChief —The preceding unsigned comment was added by 202.84.36.64 (talk) 17:41, 21 January 2007 (UTC).

Relativity uses the speed of light in a vacuum:( In air, water, glass &c light slows down:) Therefore other particles such as electrons, which travel at close to the 'speed of light in a vacuum' are travelling faster than the light does in water:)Hidden secret 7 17:46, 21 January 2007 (UTC)

To amplify on Hidden secret's answer, the speed of light travelling through some medium (material) is equal to the speed of light in a vacuum divided by the medium's index of refraction. In water (index of refraction = 1.33), for example, light travels at 3·10⁸ m/s / 1.33, or about 2.3·10⁸ m/s. Small particles travelling faster than 2.3·10⁸ m/s (which is perfectly legal under relativity theory) and slower than 3·10⁸ m/s (which is the limit imposed by relativity) will show the glow of Cerenkov radiation. TenOfAllTrades(talk) 18:54, 21 January 2007 (UTC)

Ornithopters again.

A few days ago the only answer to a question about the size to weight ratio of an ornithopter was that it was very difficult to work out. So I have decided to try a different way of asking.

1 Does anyone know anyone that could help me with this?

2 Can anyone give me any advice on how to work it out? If I can get a little bit or information from a few people, I might be able to work out the rest myself.

3 Can anyone tell me how I can calculate the ratio from a smaller version, multiplying each value by a cetrain amount?

4 &c.Hidden secret 7 17:42, 21 January 2007 (UTC)

You could do tests with identical ornithopters (perhaps rubber band powered) at three scales, say 1X, 2X, and 4X, then plot the excess weight each can carry as a proportion of the weight of each test ornithopter. Next, run a curve through those test points and extrapolate the curve. You will find a scale at which the ornithopter won't be able to support any excess weight. You can then run some calcs to determine the projected weight the ornithopter could carry at each scale. StuRat 05:42, 22 January 2007 (UTC)

Unless you find a reference desk user who has not contributed to the Ornithopter article, one doubts if you are going to get much more in Wikipedia. The external links in that article, such as the University of Toronto ornithopter project and The Ornithopter Zone, look more promising, with pages for forums and questions. --Seejyb 08:36, 22 January 2007 (UTC)

Photons

According to E=mc², the energy is equal to the mass x the speed of light in a vacuum squared, but what if something that has no mass, such as a photon, is introduced to the equation. Shouldn't that come out to be E=0? That couldn't be true because a photon is a small packet of energy. Please explain what I'm missing here. :-) Imaninjapirate^{talk to me} 18:05, 21 January 2007 (UTC)

The popular equation is only part of the story. The full equation is $E={\sqrt {p^{2}c^{2}+m^{2}c^{4}}}$ (where E, m, and c you already defined and p is the momentum). For a massive object at rest, this reduces to E=mc². But for photons (which can never be at rest because they always move at the speed of light) it reduces to E = pc, which is never zero. -- SCZenz 18:17, 21 January 2007 (UTC)

Ah, I see, thanks for the clarification. :-) Imaninjapirate^{talk to me} 18:28, 21 January 2007 (UTC)

how do get momentum though? both relativistic and no relativistic momentum requires rest mass?--137.205.79.218 00:47, 22 January 2007 (UTC)

Interesting. I didn't know the full equation either. --Proficient 01:34, 22 January 2007 (UTC)

The de Broglie hypothesis states that $p={\frac {h}{\lambda }}$, where h is the Planck constant and λ is the wavelength. For a photon of visible light, λ =~ 500 nm, so momentum = 1.325 × 10^-27 . Therefore, E in this case is about 3.972 × 10^-19 joules. This formula works for any wavelength of light. Laïka 11:10, 22 January 2007 (UTC)

Photons have no rest mass, true. But they're not at rest either. The above posts about momentum are correct, but another way of looking at it is to consider a hollow box with perfectly reflective interior that contains some (at least two) photons whose momenta add to 0. The resulting object has more mass than the box alone precisely in accord with $E=mc^{2}$ applied to the photons' energy. However, the two effects (energy corresponding to mass and to momentum) don't stack because in the short formula m is relativistic mass while in the long formula it's invariant mass; these two are the same for an object at rest, but (again) photons don't do that. Alternatively, see the photon article's discussion of weird mass addition rules. --Tardis 22:40, 22 January 2007 (UTC)

Biology

Why is it difficult to formulate a simple definition of life? —The preceding unsigned comment was added by 72.89.196.47 (talk) 19:48, 21 January 2007 (UTC).

Because life isn't simple! In school we use MRS NERG - movement, respiration, sensitivity, nutrition, excretion, reproduction, growth. If it does all of those it's alive. Theresa Knott | Taste the Korn 20:00, 21 January 2007 (UTC)

But is it not alive if it doesn't meet all of them? Somehow I think in there lies the rub... --24.147.86.187 01:30, 23 January 2007 (UTC)

I recall an episode of Star Trek: The Next Generation that addressed this issue. When a crew member tried to define life, Data pointed out that fire met all the given criteria. Vranak

Formulating a simple definition for life is not difficult. What is difficult is coping with it. — Kieff 21:32, 21 January 2007 (UTC)

Fire fails the sensitivity test. A fire will move towards a forest if it's blown that way, but it doesn't know there is a good "food" source there. It's not alive. Theresa Knott | Taste the Korn 22:36, 21 January 2007 (UTC)

Well, a fire is certainly sensitive to a stiff breeze. I think selectivity might be a more accurate term. Vranak

Not wanting to get side-tracked here, but many phytoplankton are free floating as well. I don't know that selectivity/sensitivity to food is key to life. --TeaDrinker 02:12, 22 January 2007 (UTC)

It would be remiss to let this issue go without looking at what our article on life has to say:

[Life is] carbon-and-water-based, are cellular with complex organization, undergo metabolism, possess a capacity to grow, respond to stimuli, reproduce and, through natural selection, adapt in succeeding generations.

If I had to pick one fundamental property off that list, it would be adaptation. Failing to adapt means death. Vranak

Well, viruses and the prions which cause mad cow disease might be said to adapt and reproduce, but do just about nothing else that would define them as alive. Sunspots can exhibit many of the signs of life, as well (movement, growth, reproduction). Defining life as "carbon and water based" may exclude many alien forms of life. StuRat 05:21, 22 January 2007 (UTC)

Hard call on whether prions are reproducing. They certainly act as templates to change a conformation of other good proteins, but would you consider that reproduction since they are acting on a protein that was produced by another organism? Do prions adapt? There are no changes at the sequence level just conformation changes. Viruses on the other hand definitley reproduce their DNA or RNA although they need the help of another organism and obviously adapt. David D. (Talk) 07:22, 22 January 2007 (UTC)

For that matter, how about chain letters, especially the online variety, which can grow and mutate and reproduce, with the more successful mutations surviving and the less successful dying out. So, are they alive ? (Sure, they need people to survive, but don't many living parasites also need hosts ?) StuRat 22:34, 23 January 2007 (UTC)

See, that's my point. For the most part of our history, we regarded life as a magical, mysterious thing. We even thought only live things could generate organic molecules. Nowdays, from a strictly scientific point of view, life is but a collection of atoms moving about in a certain curious way. There's nothing physically or chemically special about it anymore, and that's why most definitions of life fail: because people are not willing to give up the idea that life is "special" and fundamentally defined by a single, special aspect (oh yeah, see soul for the most popular one.) Movement, respiration, sensitivity, nutrition, excretion, reproduction, growth. By this definition, early "pre-life" on Earth wouldn't be alive. They were just chemical replicators, without feeling, senses or respiration. You may ask yourself, is this reproduction? I say yes, it is, because their numbers increased by their own means. Was the capture and processing of random chemical substances nutrition and excretion? Opinions will divide this case, but I also think yes, it is nutrition and excretion. Isn't it basically the same thing that happens with modern life? Just because we're complex wrappers for basic molecular behaviors doesn't mean we're any better than initial life on Earth. We're more complex, but that's it. So in a way, I believe we are, in fact, just unwilling to decide ourselves. We want life to be special, we want it well defined on its own, when it is, in fact, just another spectrum of the natural workings of our Universe, like so many other things we've encountered so far. If I had to come up with a definition of life, it would just be something like "an unitary, chemically isolated entity of matter that has the ability of chemical self-assembly and self-replication." A virus wouldn't be alive, since it is unable of self-assembly or self-replication (it needs to hijack something that does.) A prion wouldn't be alive either, it can just modify existing entities. Nor would be a crystal, because its units are not chemically isolated. (is there any form of modern life that's not isolated?) The important thing is, if you want to come up with a definition, it has to be a line that divides everything in two groups. The subjects won't change because of the definition, so whatever definition you pick is largely irrelevant, but at least you made up your own mind about what to call them, and that's as good as it gets. Just make a decision and deal with it. — Kieff 10:09, 22 January 2007 (UTC)

Lots of living things don't meet these criteria:) Men can't reproduce, and many people choose not to but are still alive:) Some things don't adapt, but haven't become extinct:) And they think life doesn't have to be carbon based, we just haven't found anything that isn't yet:) Just because something hasn't been done, it doesn't meen it is impossible:]Hidden secret 7 18:58, 22 January 2007 (UTC)

"Lots of living things don't meet these criteria" -> you're using "living things" against a definition of living things, without presenting yours (in fact, it looks like you're assuming you have one that is implicitly "the right one")... The point of my definition is that our cells are alive. We're just a collection of cells, so we're obviously alive as well. The question now is, what defines a multicellular organism? This is also important, but at least you've got the basics of "life" covered. — Kieff 21:52, 22 January 2007 (UTC)

You can eat it, or throw it away...

I have an apple that has turned to a giant bruise and is started to leak liquid that smells like vinigar. Can I mash it up and incorporate it into banana bread? --Seans Potato Business 20:16, 21 January 2007 (UTC)

What have you to lose by just giving it a try? Make a small batch and see what it's like. ny156uk 20:30, 21 January 2007 (UTC)

Taste a bit - If as I imagine it will taste vile then you will have your answer.87.102.33.178 20:51, 21 January 2007 (UTC)

If it were me, I'd just cut out the affected area. Vranak

That would leave me with the stalk! :) --Seans Potato Business 22:03, 21 January 2007 (UTC)

How expensive are apples in the place that you live? In most places, one bad apple is usually an acceptable, replaceable loss. Consider composting the bruised apple, (so that nothing is wasted) and buy a fresh one. Nimur 21:48, 21 January 2007 (UTC)

Throw it into the garden. Apples seem to be a blackbird's favourite food - whatever condition they're in. --Kurt Shaped Box 22:07, 21 January 2007 (UTC)

Blackbirds! They have leaves and soil to eat. What about me?! Could it potentially make me ill? Even if the are things in there fermenting it, they're adapted to survive in cold apples right, and I'm a warm person? --Seans Potato Business 22:32, 21 January 2007 (UTC)

Hmm botulism bacteria are adapted to live in poorly canned corned beef tins. They are dangerous to humans, not because they attack the body directly but because , while living in the can , they make a toxin. Theresa Knott | Taste the Korn 22:41, 21 January 2007 (UTC)

I've eaten badly bruised apples many times. They never seem to have done me any harm. Ditto for brown bananas - they look nasty and are a bit mushy but they taste fine. --Kurt Shaped Box 22:50, 21 January 2007 (UTC)

Well I've done it now. I've pushed the button and there's nothing left to do but wait... and wait... (will report back) --Seans Potato Business 23:13, 21 January 2007 (UTC)

What did it taste like? Theresa Knott | Taste the Korn 23:23, 21 January 2007 (UTC)

It's not disimilar from my usual banana bread. Sweet, a bit tougher than usual (but I don't measure the time (or even the ingredients accurately) so my results vary a lot anyway. The mixture didn't rise as much as I'd have liked but maybe there wasn't enough baking powder. As always, I had the problem where a skin forms as the outside of the bread cooks first and then the inside mixture expands and bursts out like some sort of cancer, trying to reach the back of the oven (not a very asthetically pleasing bread). I think being toucher makes it easier to cut small slices though. It's quite moist. I'm rather pleased with it... and if I don't get ill or die then all the better. :) --Seans Potato Business 00:07, 22 January 2007 (UTC)

Please stop eating the bread and throw it away. Thanks. Hipocrite - «Talk» 04:26, 22 January 2007 (UTC)

Heh...heh...heh...they think I'm CRAZY. But I know better. It is not *I* who am crazy. It is not I who am MAD! Didn'tcha hear 'em? Didn'tcha see the CROWDS? Oh my beloved apple loaf...how I love to lick your creamy center! HOOOWWWWWW... ...and your oh-so-nutty chocolate covering! You're not like the others...you like the same things I do! Waxed paper...boiled football leather...dog breath...We're not hitchhiking anymore! We're RIDING! --Seans Potato Business 11:09, 22 January 2007 (UTC)

Seans, I appreciate your enthusiasm, but we like to keep an air of decorum here at the Reference Desk. When things descend into whimsy and joking, it drives people away ^{See last September/October}. Thanks. Vranak

Sorry... --Seans Potato Business 07:26, 23 January 2007 (UTC)

Feed it to your least favorite son 69.150.209.15 21:19, 22 January 2007 (UTC)

When the gulls are eating together

What do those cackles, squawks and gabbling noises mean when they're all close together eating? --84.71.105.35 22:17, 21 January 2007 (UTC)

Probably just general chit-chat. You wouldn't be overly concerned about the details of an Italian family sitting down for a boisterous meal, and I see little reason that gulls' squawking and gabbling would be much different. Vranak

Sometimes they seem to squwak at others telling them to "back-off, this is my food" if food is scarce, but otherwise it seems to mean "Food!! Food HERE!!!"... Or maybe just the imagination of a bored school boy watching gulls eating food scraps... :p --antilived^{T | C | G} 02:44, 22 January 2007 (UTC)

Antihypertensive Foods?

Are their any foods or supplements that naturally act as a mild antihypertensive? -Quasipalm 22:45, 21 January 2007 (UTC)

Did you read the article you linked to? See http://en.wikipedia.org/wiki/Antihypertensive#Herbals_provoking_hypotension although do note that the list lacks citations. Theresa Knott | Taste the Korn 22:51, 21 January 2007 (UTC)

adrenal glands

what is affected if the adrenal glands are removedDrizzit1966 i think it is the urinary system but a friend says the reproductive system. who is right? -- Kelly

Have you seen our article on the adrenal gland? It does play a role in the reproductive system in that it produces several sex hormones, that's about the biggest link out of those two. Primarily though, it produces the bodies corticosteroids and adrenaline, which is neither urniary or reproductive. Vespine 02:52, 22 January 2007 (UTC)

I believe most glands are categorized in the endocrine system, even if they serve functions in other processes. Nimur 03:47, 22 January 2007 (UTC)

The effects are described in the article on Addison's disease. You will have to follow the links to understand most of the terminology used, and the few I have followed do explain the terms adequately, so you should get your information. Both kidney function and reproduction are affected, though the latter is not discussed in the article, except to mention that pregnancy may lead to a lethal Addisonian crisis. --Seejyb 05:55, 22 January 2007 (UTC)

Hypothetical

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

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

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

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

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

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

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

Amp hours...?

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

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

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

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

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

Stethography

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

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

Planetary positions in the future

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

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

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

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

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

Water Fuel

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

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

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

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

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

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

Blood conductivity.

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

You may wish to review [21], and [22]. Conductivity of the blood changes, based mostly on the count of red bloodcells. This is often measured for stroke patients -> see [23] for an interesting method by which it is measured. Hipocrite - «Talk» 15:56, 22 January 2007 (UTC)

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

Crazy Voice

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

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

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

References

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

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

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

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

DEBATE HELP ON GLOBAL WARMING

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

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

Thanks All

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

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

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

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

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

"There is a consensus of global warming."

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

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

"This is a moral issue."

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

I might be too late, but here is a snippet from an article. [24] I read the whole article, and it basically says that when the earth was in a big cooling cycle from 1940-1970 everybody was screaming that an ice age was coming (and CO2 was still rising!). They came up with extrapolations and pseudo-correlations with sulphates in the atmosphere. Now we are in a warming cycle and the CO2 is still rising. So this article points out that there is a history of extrapolating something that could not be linear. --Zeizmic 22:52, 22 January 2007 (UTC)

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

In that case, I am in favor of using plain old simple facts without any twisting, cutting out, or lying (usually from lack of information). You wouldn't admit that it is happening, because it is happening. The debate that is worth looking at, is how much of it is anthropogenic, and how accurate models are. I know I have probably written far too much information on the subject at the reference desk before, such as here, but I would like to note on Zeizmic's quote that "there is a history of extrapolating something that could not be linear." "could not be linear" is the key phrase here, because delta-CO₂ and delta-T are related logarithmically, not linearly. If you're in the mood to read (you have to be if you don't want to die in the debate, since scientific law states that the skeptic has the "burden of proof") you can read [25][26][27]. It is a terribly difficult debate to win since you have little time, likely most of the voters have already made up their mind, and, "if your side of the debate takes 3 minutes to explain, you'll convince 'em; if it takes 3 hours to explain, you mine as well not spend you time trying." Too bad for us it takes 3 weeks to explain your skepticism. Good luck! X [Mac Davis] (How's my driving?) 04:17, 24 January 2007 (UTC)

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

And finally the issue comes down to money. Scientists that study events that can doom civilization and destroy life as we know it get a lot of money to investigate what it is and how to stop it. Scientists that investigate a natural phenomena that has been going on for millenia with just gradual effects on civilization don't get a lot money. So it stands to reason that scientists that need money for research will always be studying phenomena that will destroy civilization. THis isn't a slight on scientists, but rather a Darwinian outcome. Scientists that believe Global Warming is a giant, serious problem simply outlive those that don't because they receive plenty of money while the skeptics have to find a different subject if they want to eat. A good read for background is the Authors note in "State of Fear"[28] titled "Why politicized science is dangerous." It is a scary thought that scepticism in science is met with derision especially about such a poorly understand phenomena such as weather. It was only 8 months ago that the climate experts predicted a catastropihic hurricane season in the U.S. due to global warming. In hindsight the scientists now say the catastrophic hurricane season was suppressed by a global warming induced El Nino. They might as well blame voodoo. The thing to look for next is the subtle lexicon change as the average temperature and sea level rise doesn't materialize. It will change from "Global Warming" to "Climate Change" and the hysteria will simply move to weather related catastrophes that are part of our natural, ever changing world. One more thing: Water vapor is by far the most important greenhouse gas. It is not known whether warming will increase cloud cover and reflect more energy into space (cooling phenomenon) or whether the increased water vapor will cause more greenhouse warming (heating effect). This is pretty fundamental since the earth is largely covered by water and water is the largest greenhous gas. All the concentration on man-made CO2 seems a bit overblown when this most fundamental piece of the puzzle is unknown. --Tbeatty 05:19, 24 January 2007 (UTC)

Strange phenomenon with digital camera

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

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

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

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

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

Antibiotics question

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

About that 10-day dose:

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

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

Hydrogen Vehicles on a Mass Transit Scale

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

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

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

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

What kind of wood??

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

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

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

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

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

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

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

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

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

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

A google for wooden book covers Returns 13 million results, including: [29] [30] [31] [32] -Arch dude 02:08, 23 January 2007 (UTC)

Incendiary laser pointer: Star Wars junior?

An Associated Press story [33] claims that an unattended laser pointer set furnishings in an office on fire. I own a laser pointer and not only does it have a momentary pushbutton to operate it so it could not be left on, but it says "Class IIIa laser product. Max output<5mW." How is it possible for 5 milliwatts from a laser pointer to set something on fire? This one does not even make the skin feel warm if directed at a spot. It would, by definition take 200 seconds to deliver one Joule of energy; how long would that take to raise say a gram of paper or cloth to the point of combustion (Fahrenheit 451?), Are there super powerful laserpointers available? Why? It would be easier for a medical laser used for burning things off tissue to start such a fire, but wouldn't such a device also have a momentary switch to prevent injuries or fires? Edison 21:31, 22 January 2007 (UTC)

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

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

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

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

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

Atlant 23:54, 22 January 2007 (UTC)

What Bird Is This

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

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

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

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

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

sun's energy

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

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

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

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

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

The first thing I think of when I see that question is the radiation budget.[34][35] X [Mac Davis] (DESK|How's my driving?) 16:22, 23 January 2007 (UTC)

time

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

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

Would anyone be able to notice?

Duomillia 23:58, 22 January 2007 (UTC)

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

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

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

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

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

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

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

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

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

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

Seagulls

Lately I have been walking by the river every week or so. There are groups of vertical supports sticking out of the water where piers once existed. One group always has a bunch of seagulls, one per pole. The other groups of supports generally have no gulls or just one or two. Why would they pick that particular group of poles over another group? Why do 80% of the gulls stick together in a group and the rest go off alone? t h b 02:40, 23 January 2007 (UTC)

I blame society and making the outcasts stay alone seperate from others... or giving the rich and powerful ones more room from the overcrowded masses. Either way I still blame society :p. --antilived^{T | C | G} 06:00, 23 January 2007 (UTC)

It seems to me that gulls establish a pecking order by fighting over the 'best' perches (with 'best' being decided by some strange gull logic that's beyond me - sometimes it's the highest perch, which does make sense, sometimes not). Ever see a gull swooping down and trying to displace another gull from its perch? The gulls that successfully fight off their aerial attackers get to stand where they want - the others don't and have to make do with what's available. The lower down the pecking order you go, the less choice. There's an age aspect to it too - a juvenile (brown) gull will almost never challenge an adult for a perch and will nearly always surrender a perch to an adult. This is all intraspecific, of course. Between different species, it's decided by size - a black-headed gull will always move out of the way for a great black-backed gull, for instance. Is there anything different about the poles preferred by the gulls? Is the water shallower beneath those ones in particular? If so, perhaps it means that they can see the seabed (and anything interesting on the seabed) from there? --Kurt Shaped Box 13:25, 23 January 2007 (UTC)

Can we please stick to verifiable facts that someone else has observed? Hipocrite - «Talk» 13:27, 23 January 2007 (UTC)

When you say it like that, it sounds like second-hand testimony is more valuable than firsthand experience. Vranak

Perhaps one support shakes with each incoming wave while the other is more steady ? StuRat 20:41, 23 January 2007 (UTC)

I don't observe any fighting over resources, they all seem to be just sitting, and it's along the brackish river, so there is no perceivable difference except maybe the area they are on is close to the garbage pier, but they don't appear to go to the garbage pier. t h b 12:22, 24 January 2007 (UTC)

Ducks

There is a group of ducks that lives near the river. They are usually on one of several grass lawn areas, pecking something out of the grass to eat. One lawn is made of artificial grass. This weekend they were on the artificial lawn eating something. What in the world could they have been eating from artificial turf? t h b 02:42, 23 January 2007 (UTC)

Food strewn by the homeowners? Seeds blown from plants in neighbouring yards? Alternatively, stop watching all of these birds (re: Wikipedia:Reference_desk/Science#Seagulls… it can't be good for your health!. − Twas Now 02:50, 23 January 2007 (UTC)

I'd go with the idea of seeds from trees, like those "whirligigs" that spin as they fall. StuRat 20:34, 23 January 2007 (UTC)

The artificial turf is on a pier. Something might have blown there but they were digging around for at least an hour. I don't think anybody was feeding them, it was a cold day and few people were about. t h b 02:59, 23 January 2007 (UTC)

Could bugs live in artificial turf? Vespine 03:15, 23 January 2007 (UTC)

It could be bugs, but what would the bugs be doing there? Trying to avoid ducks? − Twas Now 03:20, 23 January 2007 (UTC)

That's it. Ducking ducks. -- Barringa 04:14, 23 January 2007 (UTC)

Maybe they were getting nesting material. Ducks do nest, don't they? Clarityfiend 05:12, 23 January 2007 (UTC)

Can we please stick to verifiable facts that someone else has observed? Hipocrite - «Talk» 13:29, 23 January 2007 (UTC)

Oddly enough, there don't appear to be any scientific studies of what ducks pick off of AstroTurf lawns. Perhaps a lobbyist is working on getting funding for just such a valuable study as we speak. StuRat 20:36, 23 January 2007 (UTC)

Dammit! This is all George Bush's fault. Clarityfiend 02:20, 24 January 2007 (UTC)

They did appear to be digging and eating, just as they do on the natural lawns. I will go look if they are there again. However, they crap a lot and I don't really want to crawl around in it. t h b 12:25, 24 January 2007 (UTC)

Experiments for time dilation

Are there any experiments someone can do at home to see effects of time dilation? I highly doubt there are, but I just think that if there is one I can do, and it works, it would probably be the coolest thing ever. :-) Imaninjapirate^{talk to me} 04:15, 23 January 2007 (UTC)

You could try gravitational Time dilation of General relativity by observing the difference in time kept by identical clocks; one on the roof and one in the basement. -- Barringa 04:49, 23 January 2007 (UTC)

However, the difference in gravitation, and the difference in time, will be far outweighed by the inaccuracy of the clock. You'll almost certainly need a pair of atomic clocks to make it work.-Robert Merkel 05:00, 23 January 2007 (UTC)

Or you need to excite some atoms, have them release gamma rays, and absorb those rays from the top of the building. See the Pound-Rebka experiment. I don't think this could be done as a home experiment, though. --Bowlhover 13:29, 23 January 2007 (UTC)

Well, you can't do this at home, but if you take two synchronized clocks, and leave one at home, then fly around the world in fast airplanes, I believe you might be able to measure the difference. --bmk

Indirectly, the accuracy of anything that uses GPS positioning, such as an in-car navigation system, demonstrates the effects of time dilation. Without compensating for time dilation and other relativistic effects, GPS position fixes would be out by as much as 15 metres (see GPS#Relativity) and - woah, you've just missed your turning ! Gandalf61 17:15, 23 January 2007 (UTC)

I don't think it's possible, unless you have a few spare million dollars. :-) | AndonicO ^{Talk · Sign Here} 13:27, 24 January 2007 (UTC)

String theory

Is the wave like orbit of the electron around the atom, wave-particle duality,wavelength of particles in motion given by lambda = plancks const/momentum all evidence of STRING theory? —The preceding unsigned comment was added by 61.1.131.141 (talk)

No. The electron is not in a "orbit" in the sense of planetary motion at all. See atomic orbital. DMacks 06:12, 23 January 2007 (UTC)

String theory is a quantum theory, so it is consistent with all of the quantum phenomena that you mention. However, none of these known phenomena provide direct and conclusive evidence for string theory - as our article says: String theory remains to be confirmed. No version of string theory has yet made an experimentally verified prediction that differs from those made by other theories. Gandalf61 14:57, 23 January 2007 (UTC)

You're basically asking "is quantum physics evidence of string theory" which isn't much of a question. You might as well ask "is the rotation of the earth around the sun evidence of general relativity." No, it is something that GR needs to be able to explain in order to be a reasonable theory of gravitation; string theory needs to be able to explain the nature of quantum phenomena in order to be a theory of it. --24.147.86.187 16:06, 23 January 2007 (UTC)

(edit conflict) Scientists do not look for evidence of theories, that would be a type of bias; theory is meant to describe what is already there, and predict what will happen in given situations. The quantum phenomena that you mention are things that string theory attempts to describe. "Is a wave like orbit of the electron around the atom." I know what you mean, and you're kind of close. When a particle has not been measured, it remains a wave instead of a particle, the wave function has not collapsed. The wave is described as representing the possible states of the particle using imaginary numbers. X [Mac Davis] (DESK|How's my driving?) 16:10, 23 January 2007 (UTC)

Steroids

Are steroids like prednisone anyway related to anabolic steroids? —The preceding unsigned comment was added by 76.167.159.75 (talk)

They are both steroids. Can you be more specific? − Twas Now ( talk • contribs • e-mail ) 06:46, 23 January 2007 (UTC)

Yes, they are both steroids, so how are they related? Why are they both called steroids when they produce such different effects? What do they have in common?

By virtue of being in the chemical family of steroids. No really, that's it...the molecules have a similar structure; nothing at all to do with biological effect. The structure is not specific enough to assign major medical properties to "all steroid chemicals". DMacks 08:15, 23 January 2007 (UTC)

I believe the confusion is that when people say "steroid", they usually mean "anabolic steroid". --Kainaw ^(talk) 08:27, 23 January 2007 (UTC)

When doctors prescribe say, topical steroids people always freak out a little bit  :) X [Mac Davis] (DESK|How's my driving?) 16:04, 23 January 2007 (UTC)

I wonder how many people are secretly coating themselves in topical steriods in an attempt to bulk up their muscles? Probably the same ones who call "Smiling Bob" for their free trial of "male enhancement" supplements. --Kainaw ^(talk) 10:07, 24 January 2007 (UTC)

Working Out

I'm currently trying to lose weight, and my personal trainer tells me not to have protein shakes after we workout. Does this sound right? He said don't take any protein now, we will overload on protein after you lose the weight. But I am still damaging the muscle when we workout, so shouldnt I drink protein shakes? —The preceding unsigned comment was added by 76.167.159.75 (talk)

You don't need to consume a lot of protein in order to build or repair muscles. Most Westerners eat too much protein, and therefore for us things like protein shakes are just empty calories. You should focus on eating a balanced diet that has a high nutrient value per calorie. That being said, I am not sure about what yourpersonal trainer said about no protein? That's not right. Protein helps you feel full, so you're less likely to overeat. Nutritious protein also contributes to your overall health. Good luck! Anchoress 06:29, 23 January 2007 (UTC)

If you are trying primarily to lose weight, you are probably doing low intensity workouts for long periods of time (or should be) and using a type of muscle (slow witch / oxidative) that doesn't really need any upkeep besides a steady nutritive flux. Your trainer is right to limit calories, be they from carbohydrate, fat, or protein. ^tucker/_rekcut 12:26, 23 January 2007 (UTC)

Why do animals cock their heads?

Why do animals cock their heads when they're confused or interested in something? Sometimes my cat will tilt her head 90° to the left or right when she's looking at me or following a bug on the wall. What for? —Angr 06:34, 23 January 2007 (UTC)

I don't know about your cat, but not all animals have binocular vision. See also parallax view. Anchoress 06:37, 23 January 2007 (UTC)

Hmm.. according to Binocular vision, predatory animals like cats do tend to have it; and as you can see from her picture here, her eyes are positioned on the front of her head, not on the sides. I've heard that parallax is the reason why cats sometimes sway their heads from side to side when looking at something (especially something they're about to pounce on), but the head-cocking thing is different. I get the impression she does it when she's wondering what's going on, though that could just be anthropomorphism on my part. —Angr 06:58, 23 January 2007 (UTC)

It might also have to do with hearing. Lots of times we cock our heads to get a different bead on a sound - distinguish direction, hear better, etc. Anchoress 07:04, 23 January 2007 (UTC)

Don't humans do it too? Vitriol 14:42, 23 January 2007 (UTC)

I certainly do. Vranak

My inside budgie always cocks his head when I'm talking to him. --Kurt Shaped Box 23:21, 23 January 2007 (UTC)

I believe Anchoress is right. Dogs will cock their heads when the sound is coming from in front of them in order to change the position of their ears and better catch the sound. --Joelmills 18:27, 23 January 2007 (UTC)

Sound localization#Binaural cues. Melchoir 19:27, 23 January 2007 (UTC)

I dunno. I was babysitting one time and the 1-year-old cocked his head to look at something - there were no unusual sounds from that direction. Clarityfiend 22:37, 23 January 2007 (UTC)

Parallax distance judgement works best when the subject is in the vision plane of the eyes. Try it sometime: go to the top of a hill, and see how steep it looks. Now, tilt your head sideways -- the hill should look far less steep, and closer to the actual slope. --Carnildo 23:12, 23 January 2007 (UTC)

Prana-bindu

In the Dune novels the Bene Gesserit are taught a fictional training style know as Prana-bindu. It apparently allows them to control any muscle is there body independently. My question is, is this level of control even possible? And, are there any real world martial arts or other disciplines that practice similar abilities. Thanks! S.dedalus 07:15, 23 January 2007 (UTC)

For brevity, I will be very general. There are two rather interesting parts of your brain that sit side by side. One is a layer that receives information from nerves all over your body. The other is a layer that sends signals to all the parts of your body. What is rather cool about them is that the brain cells are arranged on those layers in a very similar pattern to the way the human body is arranged. The proportions are different though. For example, in the receiving part the fingertips are huge compared to the arms because you sense more with your figertips than your arms. In the sending part, the legs are huge and the feet are rather small and often appear to be lacking toes. That is because you have a lot of control over the muscles in your legs, but very little over your feet and toes. With all of that description, you can see why I'm being so overly general. But, understanding how it works, you can see that to gain control over a new muscle will involve either losing control over another muscle or somehow forming new brain cells to add to the existing ones. It is my opinion that children are capable of quickly creating new cells or training currently unused ones. Adults have pretty mush got their brain set up and find it difficult to learn a new trick. I was just reminded of watching an old lady try to use a cell phone. She had to hold the phone in one hand and use just one finger on the other to press each button one at a time - slowly. Imagine her trying to learn the thumb-numbing practice of texting. --Kainaw ^(talk) 08:25, 23 January 2007 (UTC)

To clarify Kainaw's comment, learning is not a matter of gaining new brain cells, but rather it involves making connections between existing brain cells (in obscenely simple terms). − Twas Now ( talk • contribs • e-mail ) 08:45, 23 January 2007 (UTC)

Sensory (left) and motor (right) homunculi.

This is slightly unrelated to your original question, but is in keeping with Kainaw's comments: "the receiving part the fingertips are huge compared to the arms because you sense more with your figertips than your arms". Cortical homunculi show a map of the human body based on the amount of sensorimotor cortex dedicated to that body part (the sensorimotor cortex is the portion of the brain directly responsible for sensation and movement). In the image, the left figure shows a sensory mapping (i.e., the larger parts are most sensitive), and the right figure shows a motor mapping (i.e., the larger parts have more fine control). − Twas Now ( talk • contribs • e-mail ) 19:58, 23 January 2007 (UTC)

Can't people already control all their muscles:) What would be the point of having something if you can never use it:?Hidden secret 7 15:58, 23 January 2007 (UTC)

I thought he meant the ability to have conscious control over any single skeletal muscle. X [Mac Davis] (DESK|How's my driving?) 16:02, 23 January 2007 (UTC)

Controlling any muscle in the body independently is rather a tall order: muscles are connected to one another, so moving one is going to move others. Vranak

Thanks for all your help. Yes, the section on Prana-bindu mentions the ability to “bend the last joint in her little toe while remaining otherwise motionless.” The ability also apparently extends to controlling muscle groups that are not usually consciously controlled, such as the heart muscles. S.dedalus 20:31, 23 January 2007 (UTC)

Alkanes and their Boiling Points

Hi, I was given the graph where the number of carbon atoms are plotted against their boiling points (Alkanes), and it turns out to be a curve instead of a straight line. Why is that? Aren't they meant to be increasing proportionally? I couldn't find anything on WIKIPEDIA and my teacher challenged me to find a detailed IB / AS level answer, many thanks! — Preceding unsigned comment added by 218.102.23.128 (talk • contribs)

Van der Waals' forces are the cause that the alkanes stay together. If the thermal motion excedes this force the stuff boils. The Van der Waals' force is dependent on the surface area of the alkane. The surface area grows slower than the mass (volume). One with the power of two the other power of three. This might help you to find good references for the problem.--Stone 09:42, 23 January 2007 (UTC)

This paper proposes various empirical mathematical models for the boiling points of alkanes, and includes this explanation: If you plot the boiling point for the first few normal-alkanes against MW [molecular weight], it rapidly increases because the London forces increase with MW and these are the forces holding the molecules together in a liquid... But, as the chain gets longer the molecule can fold back on itself and some of the London forces are directed towards itself so the dependence of boiling point on MW diminishes. I guess this might be correct, but it could also be a post hoc rationalisation - you should try to find other sources to confirm this explanation. Gandalf61 10:09, 23 January 2007 (UTC)

Stars in the southern sky

I've been able to see the stars in the northern sky from a perfectly black ocean or a high desert mountain top, and the southern sky from a remote bush location in southern africa. I have the completely relative perception that there are more stars in the southern sky, but I wonder if that can be true? Of course, there are different constellations, and certain elements of the northern hemisphere star map can't be seen in the south, and vice versa. I've read that there are certain vast galaxies in the southern sky, but I suppose we see them as individual stars, if we see them at all. The map of the earth has more land mass in the north and more water in the south. My question is, is the 'sky' more or less filled with the same number of visable starts all around us, from anywhere on earth we can get a clear and unpolluted view, or is there any reason that the southern sky really is filled with just more visible stars and a generally more spectacular and universal vista? Thanks if you have an interesting answer.

Somewhere in my past I picked up that there are appox 3,000 stars visible in the north and 5,000 visible in the south. I have no idea where I got that from and Google isn't helping. --Kainaw ^(talk) 10:54, 23 January 2007 (UTC)

Interesting question. Googling "more stars visible" and "southern hemisphere" brings up several confirmations, such as this one. All the stars we see are within our own galaxy, and apparently the centre of the galaxy is better placed for viewing from the southern hemisphere.--Shantavira 13:09, 23 January 2007 (UTC)

Almost all the stars and other astronomical objects that can be seen with the naked eye are within our own galaxy. There are just a few objects visible with the naked eye that are outside of our galaxy, such as the Magellanic Clouds, the Andromeda Galaxy and, under exceptionally good conditions, the Triangulum Galaxy. Gandalf61 13:55, 23 January 2007 (UTC)

It is widely regarded that the southern hemisphere is better viewing then the north. The main reason is that the densest part of out galaxy: The Galactic center is positioned at a declination of about -20 degrees. This makes it higher in the sky from southern rather then northen latitudes. There are also several other spectacular objects such as the Magellanic clouds and Omega Centauri which are only viewable from the south, why those are south and not north, I just thought it was dumb luck. Vespine 21:55, 23 January 2007 (UTC)

Silicon Oil

I am making an oil cooled RF Load as a part of my project. I am thinking of using Silicon Oil as the coolant. Can anybody tell me the electrical properties of Silicon Oil, please?

As the large notices at the top of the page say, this is an encyclopaedia. The answers you are looking for are here. yandman 14:15, 23 January 2007 (UTC)

What about transformer oil? Also can you not tell us what power and at what frequency you are dealing with. THis would make it easier for us to help you!

See Transformer oil. See also Material Safety Data sheets for any insulating fluid you choose. A generation ago the Heathkit company sold the Cantenna [36] for ham radio operators to use as an artificial load for transmitter testing. It was a looked like a big paint can with resistors inside. The instructions said to fill it with transformer oil. The source above says they ship a can of oil with their recycled Cantennas. They might sell the oil alone. I suppose some hams just asked nicely at the testing/maintenance department of the local electric utility, who buy the stuff by the drum or by the train tank car load. Do not even consider just draining or siphoning oil from a transformer. See also [37] for home brew 1 KW wet dummy loads. See also [38] re: transformer oil sources. Utilities once used mineral oil in transformers to cool and insulate the transformer windings and core. It had to be tested with a high voltage tester to make sure the moisture content and acid content was excruciatingly low, because any moisture would reduce the insulating quality and cause flashovers. It was flammable. Askarel/Pyranol/PCB was used instead of oil as a nonflammable (or less flammable) coolant and insulator until the 1970's, but electrical arcing would convert it into dioxin, very bad stuff. Old utility transformer oil (mineral oil) was likely to be somewhat contaminated with PCB because the same tanks and filter presses were used for both oils. Utilities went through a frenzy of testing and elmininating PCB, but some transformers may still be PCB contaminated. Motor oil is not recommended as a substitute. The replacement for Askarel was silicone fluid, which had many of the same advantages as Askarel, but could reportedly explode if it had much moisture in it and there was an arcing fault in the transformer. So dry silicone oil is a great insulator and a good heat transfer medium, but explosive if contaminated with moisture and exposed to high temperature and electrical arcing. It is far less of a biohazard than Askarel or petroleum oil. Online I do not see any references to the usability of silicone oil in a cantenna, so you would need to do further research into the feasibility. For safety, be aware that under extreme heat or in the presence of arcing, transformer oil can break down and release combustible gasses. If there is sufficient oxygen in the enclosure, in the presence of a flame or spark these can detonate and rupture the container, followed by an intense oil fire. The fluid expands when heated. Part of your design can be looking at the specific heat of the fluid you use to see how much it will heat up over how long (neglecting radiation out) and its expansion coefficient to see how much that would make it expand. It could come squirting out a relief valve on the top, so provide for that with containment under the can. Your RF load must somehow make provision to transfer the heat of the power dissipated to the surrounding atmosphere by some means. That is an essential part of the design. Youi might wind up rating your RF load at so many watts for so many minutes like tha Cantenna. A thermometer or thermocouple might be used to sense the oil temp and the resistor temp, with an alarm. If the resistor is partly out of the fluid or in the wrong position there will be local overheating and an danger of fire or explosion. Remember that the device is basically a powerful heating element in a fuel tank. Small oil filled poletop transformers may transfer the heat by internal convection and by radiation and conduction to the air from the cylindrical can itself, or higher wattage units may have radiators on the outside. Substation transformers have pumps connected to the radiators and fans to cool them. On a really bad day, they train fires hoses on the steaming transformers, creating a problem with moisture creeping in. Water cooling was tried, with internal or external cooling tubes and circulating water. This introduces additional obvious mechanical complexity. The internal tubes sometimes leaked. The transformer fluid absorbs oxygen and moisture if exposed to the atmosphere; a dry nitrogen blanket is often placed above the oil level in a transformer. Filling a container to the brim and sealing it will be a problem because of the expansion of the fluid when heated; some utility transformers had a conservator tank above the transformer to make sure the oil could expand but the trnansformer stayed full. The conservator had a pressure vent for air to go in and out. Electrical transformers filled with oil must be in special fire resistant transformer vaults if indoors. Transformers and oil filled circuit breakers are provided with pressure relief. You are probably aware that the resistance and inductance at DC or audio frequencies will not be the same at RF or microwave frequencies. Good luck with your design. Edison 16:35, 23 January 2007

Thanks a lot!!!

Stem Cell Research Global Funding

I have searched on the 'pedia for a while, in addition to interrogating google, and I have not been able to find any data on how much funding SCR has gotten in countries other than the US of A. Except once, a few days ago. I didn't favorite it and I was on a public computer and don't have access to the history, but I know it's out there somewhere. So if someone could possibly assist me in my search, or even give me a chart, of the funding stem cell research has gotten, by country, that would be great :). -- GofG _|^|_| Contribs 16:39, 23 January 2007 (UTC)

This probably isn't sufficient for your needs, but this might help. It shows every country's permissibility toward stem cell research. I might make the assumption that, based on a country's level of permissibility and GDP, one can make general conclusions as to how much they fund the research. For example, Japan is rich and permissive, so they would contribute a larger portion of their GDP (say 0.05%) to stem cell research, while a restrictive country like Germany might contribute only 0.001%. On the other hand, Iceland is more permissive than the U.S., but the U.S. might still contribute the same amount or more, since they have much more money at their disposal. Generalities… maybe useless for your purposes. − Twas Now ( talk • contribs • e-mail ) 18:28, 23 January 2007 (UTC)

Ambient Infrared/Ultraviolet

About how much ambient infrared (near and far) and ultraviolet light exists that, say, a sci-fi-type organism that can only see infrared and ultraviolet light (but for some odd reason not visible light) would be able to see on Earth? What kind of change would occur from day to night, and what kind of differences would artificially lit environments have to naturally lit environments (from the extremes of being in a room shielded from natural light that's still lit to being outside with no artificial light, for example)? To anyone that takes the time to read this and respond, thanks!~ 67.83.72.38 17:28, 23 January 2007 (UTC)

Sunlight provides lots of near-UV and lesser amounts of the higher energy UVs (UV-A and UV-B) and essentially all UV-C is blocked by the ozone layer. Surprisingly, there's not all that much near-IR floating around (as you prove every time you use your TV clicker to mute the commercials; its pretty wimpy infrared LED is bright enough to be seen by the TV even if you're not pointing the clicker right at it.)

And UV and IR vision does exist. For UV vision, see the Claude Monet article for a reference (near the bottom) to his changed vision after he had his cataracts (and eye lenses) removed; this may also be the rather-terrestrial explanation for the character in the sci-fi story K-PAX. Our article doesn't mention it, but honey bees are widely assumed to be able to see in UV as well. And for far-IR vision, see pit viper.

Atlant 17:50, 23 January 2007 (UTC)

"Bee's purple" X [Mac Davis] (How's my driving?) 22:58, 23 January 2007 (UTC)

measurement standard of blade sharpness

Is there a standardized measurement for blade sharpness. ie scalpl, razor, kitchen knife?

I have not been able to finad an ASTM, ANSI, DIN or other standard for this measurement

Thanks Conrad A. Smith Moonraker72 21:18, 23 January 2007 (UTC)

Interesting, I used to work in a tool shop and we would have different things sharpened by a professional sharpening service, router, planer and saw blades, I've never heard of a standard for sharpness. That does not mean one doesn't exist. Vespine 21:40, 23 January 2007 (UTC)

Often times blades are rated by minimum thickness in µm. X [Mac Davis] (How's my driving?) 23:47, 23 January 2007 (UTC)

Perhaps 10 years ago I read of a man who had devised a new knife sharpening doodad and had devised a sharpness test, but I don't remember what the test was. Seems like ASTM would have devised something, like measuring the pressure required to cut a standard piece of paper. My youthful sharpening efforts usually resulted in someone saying "Wow, that knife is so sharp it would cut warm butter," so that would be the easiest test. Edison 00:05, 24 January 2007 (UTC)

Better than mine, all I got was "Wow, that knife is so sharp it could cut melted butter." X [Mac Davis] (How's my driving?) 03:53, 24 January 2007 (UTC)

Interesting question. I can see no reason why there shouldn't be an objective test for sharpness, but Googling "blade" and "measure how sharp" produces only one hit, which is an interesting one, though there are no further hits for his "Anago Sharpness Tester".--Shantavira 09:43, 24 January 2007 (UTC)

Wouldn't it be a lot simpler to just search for "sharpness tester"? I did that and turned up [39] Apparently it measures sharpness in force required to cut a test sample. I also got [40], which is kind of goofy but interesting. Night Gyr (talk/Oy) 11:20, 24 January 2007 (UTC)

Burled wood

I have this wood burl that is about 6 by 9 by 4 that I wanted to display but I can't figure out what kind of objects or surfaces to make that will render the greatest surface area. One idea is a series of ever decreasing size bowls or maybe knife or gun handles. Where can I find some examples of what has been made out of burled wood and how it was done? -- Barringa 21:41, 23 January 2007 (UTC)

Google for images of "wood turning burl bowl". You will see lots of examples. You will need a wood lathe and perhaps some unique tools to make nested bowls. Rmhermen 23:36, 23 January 2007 (UTC)

Tame budgies falling asleep when spoken to softly...

The topic on animals cocking their heads in response to sound reminded me of this. When I talk softly and quietly to my budgie when he's in his cage (with my face close to his), after a while I notice him starting to get sleepy - his eyelids droop, he fluffs his feathers up, he starts clicking his beak (as tired budgies do). Sometimes he even tucks his head into his back and falls fast asleep for a couple of hours. I've noticed that he does the same if I sing softly to him, or even make a low-pitched rumbling noise in the back of my throat. All the budgies I've kept as pets have done this, so it's not something particular to this bird. Anyone have any idea why I have the ability to send budgerigars to sleep (no, it's not because I'm a boring person - before anyone says it ;) )? --Kurt Shaped Box 23:32, 23 January 2007 (UTC)

The alpha bird in the flock is present and taking care of them, so what's to worry about? Time to catch some Zzzzs... I think you'll find this actually a pretty common parrot behavior.

Atlant 00:40, 24 January 2007 (UTC)

I would guess you are producing something close to the sounds it's parent(s) made, which it finds relaxing. StuRat 06:54, 24 January 2007 (UTC)

Yes, I'm pretty pretty sure it's not boredom;-) --Shantavira 08:49, 24 January 2007 (UTC)

January 24

non-venomous snakes

Which snakes are non-venomous, like Garter Snake for example? I doing a video about girls dancing in naked with non-venomous snakes. I did read the article about the non-venomous snakes but, it said some snakes like Boomslang are venomous. Can someone tell me which snakes are non-venomous?

See Snake and Venomous snakes, and check library books to be sure. Some can be easily confused with others; the first Ball python I saw looked like this one [41] and reminded me of an American copperhead. Any snake can deliver a painful bite. Edison 00:14, 24 January 2007 (UTC)

Thank you for your help.

The easiest way to do it is usually to locate which snakes are venomous and work backwards from there. Even easier if you are talking about a specific region — it is pretty easy to tell which snakes in North America are poisonous, for example (vipers and the coral snake, and that's about it). --24.147.86.187 02:14, 24 January 2007 (UTC)

Videos of girls dancing naked with snakes? Tell me when you're done taping, I want to buy one! None of my snakes could dance. X [Mac Davis] (How's my driving?) 03:54, 24 January 2007 (UTC)

Buy a video, a girl, or a snake?Edison 05:03, 24 January 2007 (UTC)

Snakes on a dame! --Zeizmic 12:58, 24 January 2007 (UTC)

Zinc and HCl reaction with copper catalyst

Can anyone tell me what the effect of a catalyst, preferably copper, would have on the reaction of HCl and Zn? Further I would like to know how I could prove this in an experiment?

Thank you so much —The preceding unsigned comment was added by 198.54.202.250 (talk)

By definition, adding a catalyst to a reaction will accelerate it. What effect some specific material would have (does it catalyze a certain reaction, and by how much) is the question. To "prove this in an experiment", well that just mean you try it and see what happens (Zn+HCl, with and without a certain catalyst added). I have no idea how copper would affect this particular reaction. DMacks 01:45, 24 January 2007 (UTC)

Catalysts lower the activation energy of a reaction, making this barrier easier to overcome. Notice that copper (Cu) is not in the equation. That is because it is not consumed by the reaction. Basically, it goes in one end as copper, and comes out the other as copper! The chemical equation to this reaction is as follows:

Zn _(s) + 2HCl _(aq) → ZnCl_{2 (aq)} + H_{2 (gas)}

− Twas Now ( talk • contribs • e-mail ) 04:23, 24 January 2007 (UTC)

Electricution by speakers

My amp outputs 100W for each speaker. from reading the article on speakers, i understand that its simply an electrical signal. why is it if i grab the 2 wires to each speaker with my fingers i dont get electricuted? 100w should be more than enough to give me a jolt, no?

The voltage is probably less then 50 v pk. not enough to cause any appreciable current unless you stuck the wires thro your skin and into the blood stream (dont!)--Light current 03:22, 24 January 2007 (UTC)

Most speakers are 8 ohms. Simply speaking, 100 watts into 8 ohms gives 28 volts. Although if it's a stereo amp, that's probably 50 watts/channel, for only 14 volts. Definitely not enough to shock you, although if you got your fingers wet and cranked some punchy music up real loud, you might be able to feel a little tingle.

If it were possible to shock yourself with ordinary audio amplifiers and speakers, they would require much more substantial wiring, with protective insulation at the connections. The fact that no such special wiring is required is one clue that the voltages involved are generally regarded as safe.

—Steve Summit (talk) 03:36, 24 January 2007 (UTC)

You would be much more likely to burn yourself, like me. X [Mac Davis] (How's my driving?) 03:50, 24 January 2007 (UTC)

This is not a subject I am highly knowledgeable about, but I think it is the voltage which determines whether or not you get shocked, not wattage. − Twas Now ( talk • contribs • e-mail ) 04:27, 24 January 2007 (UTC)

Of course with a tstepup transformer it would be quite possible to electrocute someone with the output of a stereo amplifier. There was a case where someone did just that. (And we all know AC is more deadly than DC.) Edison 05:05, 24 January 2007 (UTC)

It's a combination or amps and volts that's dangerous. The electric shock article has descriptions of the dangers. 05:15, 24 January 2007 (UTC)

True, although it's really milliamps and volts. (In particular, a 15 amp, 120 volt circuit is no more or less dangerous in terms of electrocution hazard than 20 amps, or 1 amp, or 100 amps.) —Steve Summit (talk) 13:49, 24 January 2007 (UTC)

Sound energy

is the total sound energy calculated as Amplitude X Frequency? is sound energy the same as "volume"? is there a relationship (equation) between amplitude, frequency, and volume.. kind of like the way voltage, current, and power are related? — Preceding unsigned comment added by 209.53.181.151 (talk • contribs)

From sound energy density:

$E=\xi ^{2}\cdot \omega ^{2}\cdot \rho =v^{2}\cdot \rho ={\frac {a^{2}\cdot \rho }{\omega ^{2}}}={\frac {p^{2}}{Z\cdot c}}={\frac {I}{c}}={\frac {P_{ac}}{c\cdot A}}$

You might also be looking for sound intensity. X [Mac Davis] (How's my driving?) 03:57, 24 January 2007 (UTC)

Buying Copper?

Where can I purchase blocks of high purity metals, such as copper?

Ebay is the best place to look first! :) X [Mac Davis] (How's my driving?) 04:22, 24 January 2007 (UTC)

There are companies such as Alfa Aesar that sell very pure chemicals for scientific use. Alfa Aesar will sell you pure copper in many different forms. —Bkell (talk) 06:17, 24 January 2007 (UTC)

Homosexual transexual

There are humans who are transexual. There are humans who are homosexual. But are there any homosexual transexuals? - posted unsigned.

Yes - I can remember a lesbian transexual interviewed on talk radio a number of years ago, and happen to know another myself. --Neo 09:38, 24 January 2007 (UTC)

Of course. Between FTMs and MTFs you can find all sorts of attractions. I haven't seen any FTMs interested in men though. Night Gyr (talk/Oy) 11:14, 24 January 2007 (UTC)

rf load

why the tapered housing is needed in rf load? and what the dimensions of housing? means what is the distance between the housing wall and resistor?i m designing rf load for frequency up to 3 ghz and power rating up to 600watts.

How to find technical bibliography of biology professor

I have searched the internet for the technical bibliography of Professor Steven Rose a neurobiologist. I found a page that included a listing of his papers from 2000-2006 but I need his earlier papers. Any suggestions of how I could find this. I thought of posting on the talk page of the Steven Rose article but its empty so I doubt anyone is watching it. -- GrahameKing 08:13, 24 January 2007 (UTC)

Go into a public research library (such as the ones at a good university) and ask at their reference desk. They will have access to databases like Web of Science. That may not get you everything, but it should get you most of the publications in major journals.

I don't suppose you've considered just emailing Professor Rose and asking him?--Robert Merkel 11:23, 24 January 2007 (UTC)

Send me your e-mail address (go to my user page; then e-mail this user); I'll send you back a ref list for S. Rose. ike9898 14:04, 24 January 2007 (UTC)

Cooking with gas.

Is there any difference from the cook's point of view when you cook with town gas, natural gas or LPG? thanks 203.109.174.164 10:57, 24 January 2007 (UTC)

Essentially no. Town gas is usually natural gas, though is sometimes doped with LP if the natural gas feed is temporarily inadequate to satisfy the demand (on a minute-by-minute basis). Thus a substitution often happens without the notice of cooks or other gas users. However, when LP gas is used, it must be mixed with air to have the same heating properties as natural gas. LPG alone has more energy per unit volume than natural gas. ^tucker/_rekcut 11:54, 24 January 2007 (UTC)

national geographic

in the 1999 issue of nation geographic on biodiversity there is a diagram representing the species of organisms and their numbers and proportions , the problem is that i no longer have that issue with , i was wondering if any one could suggest any way to get this diagram or would anyone be kind enough to scan that image for me .

regardsMi2n15 12:02, 24 January 2007 (UTC)

Have you tried your local library? Or, try a friend. There's always someone who saves all their national geographics. I don't think scanning a diagram would fly with wikipedia's copyright policy. Night Gyr (talk/Oy) 12:05, 24 January 2007 (UTC)

Dead body reflexes

I'm looking for the word that refers to a reflex action that comes from a dead body. Hope someone has the answer. thanks for your help. marie Martin

Liquids that are safe to drink?

The article on water intoxication says that even plain old water is toxic if ingested in large enough amounts. Are there any liquids that are safe to drink, meaning that they don't induce chemical intoxication regardless of the amount ingested? JIP | Talk 14:44, 24 January 2007 (UTC)

Aside from chemical toxicity, a major concern is the osmolality of the solution. For that reason, a 0.9% NaCl solution would be just fine. Can't think of any other examples offhand. --David Iberri (talk) 14:54, 24 January 2007 (UTC)

choir boys

Do choir boys' voices break later than normal boys'?

The articles Puberty#Voice_change and Human_voice are relevant, but I can't find much on this issue in either one. I've not heard that regular singing changes when a boy's voice would change, but I really don't know. One factor that might make it seem like they change later- boys whose voices have not yet changed may be selected for singing because of this. In other words, if the boy's choir seems high-voiced, maybe it's because the boys whose voices have already changed aren't in the boy's choir anymore. Friday (talk) 15:24, 24 January 2007 (UTC)

Safety Critical Decision Making

Wiks have the potential to provide a "big brain" perspective on any topic.

How does one use a Wiki to enhance safety critical decision making when numerous single accountable individuals make up the formal decision hierarchy?

The dilema is how does one maintain accountability while leveraging the big brain?

SpaceSafetyGuy 15:29, 24 January 2007 (UTC)

Wow. Was that english? You can create your wiki, semi-protect it, and disable account creation, so that only people whose accounts you have created for them can edit. In this way, you'll know who said what (history). An example yandman 15:41, 24 January 2007 (UTC)