Revision as of 16:22, 29 October 2006

Reference Desk

October 23

The "Wholly Grail".....

Let`s talk about the Wholly Grail if we could, for a bit. More specifically, Virtual Particles. You know, those "pesky" electron-positron pairs that are alleged to exist at this level. My understanding of these 'alleged' particles is that they don`t exist long enough to be REAL...i.e. they exist for shorter than a Plank second, therefore, don`t REALLY exist at all. This could bring Hawking Radiation into question. I have, I think, a VERY interesting follow-up to this but I`d like to 'hear' everyones` ideas about these 'alleged' existances first, for fear of sounding a fool. Please, no jokes! TY Dave 205.188.116.74 00:27, 23 October 2006 (UTC)

• Is your spelling of "Wholly" meant as some sort of pun? If so, I don't get it--64.12.116.74 01:17, 23 October 2006 (UTC)

• Also, may I suggest, if you want to sign with a name, sign '''name'''~~~~~, that way the name stands out more than with name ~~~~--64.12.116.74 01:22, 23 October 2006 (UTC)

I didn`t want to include a spiritual or religious connotaion. You can call it "Holy", if you want, but I`m strictly aiming towards science. There was no pun intended, to answer your question. I have no clue what the person is talking about in regards to "signing", sorry. Please keep to the main subject. Dave 205.188.116.74 01:29, 23 October 2006 (UTC)

I too am utterly confused about the title. Since when is wholly an adjective? As for the question itself (which, funnily enough, has no question mark anywhere), who ever said virtual particles were real? I'm sure by Plank second you mean Planck time, but virtual particles can exist much longer than the Planck time (it depends on their rest energy: the more energy they have, the less time they can "get away with it", according to the uncertainty principle for energy and time). Anyway, how does any of this "bring Hawing Radiation into question"? —Keenan Pepper 04:42, 23 October 2006 (UTC)

First, will you folks please drop the "Wholly" already? It`s amazing how often you JUMP on someone over a single word, completely forgetting/ignoring the question/comment! Sheesh! Second, who said it was a question?..."Let`s talk..." Third, I DID say, ""MY" understanding of...". Perhaps I was wrong there...forgot about energy/time. Fourth, assuming I was correct, just for an instant, perhaps a Plank second even,(the tiniest piece of Plank Time, thought you`d get that!) if virtual particles didn`t "last" long enough to be 'seen' by Gravity, then that would CERTAINLY put Hawking Radiation into question! I guess I`ll save my VERY interesting follow-up for when I have some more-interested listeners/readers. Any thoughts about Vacuum Genesis? Thanks, Dave 152.163.100.74 05:49, 23 October 2006 (UTC)

The Reference Desk is not a soapbox, bulletin board or chat channel. It is meant for asking questions to which you could not find an answer.  --Lambiam 10:42, 23 October 2006 (UTC)

• That question is crackpot physics. Hawking radiation is due to virtual particles. There's nothing 'holy grail'ish about virtual particles - they're a well-understood part of mainstream physics, unlike the question which doesn't seem to have understood any of the terms it's using: Planck time is an unrelated concept to virtual particles. You can have a virtual particle for as long or short time as you want. --83.145.46.141 14:06, 23 October 2006 (UTC)

How gyrocompasses work

After reading the gyrocompass article, I spent a long time trying to figure out how it works. The article describes 2 types of gyrocompasses: the first kind is filled with fluid, while the second kind has weights that pin down its gyroscope.

I pretty much understand how the first kind works. However, according to the article: "This friction force caused by the fluid results in a torque acting on the axis, causing the axis to turn in a direction orthogonal to the torque (that is, to precess) toward true North (to the North star)". Is the torque applied in the direction opposite to the direction the axis is travelling in? If so, how will this torque cause the axis to move toward the north star?

I have no idea how pinning down a gyroscope's axis will cause it to point north. Shouldn't it point east, because that's where the stars rotate around the celestial north pole as much as they do around the celestial south pole? Can someone explain what I'm missing here? --Bowlhover 01:52, 23 October 2006 (UTC)

The gyroscope's axis points north, the gyroscope spins around its axis. It points north because it is aligning it self with the earths rotation, the earth also rotates around an axis which points north. This might give you a broader insight: equatorial mount. Vespine 06:40, 23 October 2006 (UTC)

I know that, but how does it align itself with Earth's rotation? --Bowlhover 15:37, 23 October 2006 (UTC)

Because that is the only orientation where the gyroscope's axis will not experience a change to its angle due to the rotation of the earth. Hold a pencil vertically and then spin around with your arm out, if your friend looks at the pencil, it will look like it is pointing in the same direction while you are spinning. If you hold the pencil on an angle from vertical, the place where the pencil is pointing will change as you turn. You could do this with an actual gyroscope instead of a pencil and feel the actual force involved.Vespine 01:05, 24 October 2006 (UTC)

I don't think I've made myself clear enough. So, here is what I do and don't understand:

The gyroscope is spinning around its axis. Right now, its axis is pointing toward a certain part of the sky. Earth is changing its velocity by rotating, but the gyroscope tries to resist this change in velocity (due to Newton's first law of motion). As the result, the axis will point to the same piece of sky relative to the stars. This "piece of sky" will rotate around Polaris in a counter-clockwise direction, just like the stars do.

Since the gyroscope's axis is rotating around Polaris in a circle, it will rarely point directly north. As a result, torque has to be applied to decrease the size of this circle (i.e. force the axis toward Polaris). My question is: how will submerging the axis in a fluid force it toward Polaris? --Bowlhover 04:29, 24 October 2006 (UTC)

Mercury and Fillings

Can mercury from a 30 to 40-ish year old filling come out and be hazardous to you health? Deltacom1515 02:09, 23 October 2006 (UTC) 02:05, 23 October 2006 (UTC)

Current research and the accepted beliefs of dental health organizations hold that dental amalgam fillings do not harm your health. - Dozenist talk 02:10, 23 October 2006 (UTC)

Its not done me any haarm yet >Harr, Haa HAAA haarrr!! HHAAAAA!!! HAAAAAr haarrrr!. Where is that hatter? See mercury--Light current 02:13, 23 October 2006 (UTC)

It's believed to not be harmful. Although i'd say most people who've encountered mercury in a chem lab would have doubts about that statement. We actually have an article on this, take a look Dental amalgam controversy#Health effects generally --`/aksha 02:30, 23 October 2006 (UTC)

No one is disputing the effects of raw mercury. What is at question is the safety of amalgam in fillings. 8-)--Light current 02:39, 23 October 2006 (UTC)

.....amalgam's contain mercury. --`/aksha 02:56, 23 October 2006 (UTC)

Correct.... amalgamated with other metals and therefore not RAW! Read my original post again.--Light current 03:14, 23 October 2006 (UTC)

Yaksha, I certainly do not see mercury in a chem lab ever, but I work with amalgams frequently. To repeat, amalgam fillings are not considered harmful. - Dozenist talk 03:19, 23 October 2006 (UTC)

Salt is not harmful, even though pure chlorine and sodium are extremely harmful. Just because the original subsituents are harmful, does not mean the compound/alloy is. Generally, the more reactive (and therefore, usually the more dangerous) a chemical, the safer the compounds they create. If they release a lot of energy in a reaction, it is not easy to reverse the process. --liquidGhoul 12:09, 23 October 2006 (UTC)

The question was about "Can mercury from a 30 to 40-ish year old filling come out". Amalgam isn't meant to be harmful. It's believed the mercury doesn't do anything funny. But if the mercury came out? That's the point. And my comment about the chem lab was meant to be a joke. (Although i can't really imagine why a general chem lab wouldn't have some mercury somewhere, it's not that usual. Even my high school chem labs had it, never worked out why though, it's not like they ever let students near it...) The link to the Dental amalgam controversy was meant to be my answer. The article explains it all. --`/aksha 14:02, 23 October 2006 (UTC)

Archiving

This section has been moved to Misplaced Pages talk:Reference desk#Archiving. --hydnjo talk 00:20, 24 October 2006 (UTC)

Different roles for insects in a hive/nest

Hi - this might be a silly question, but can someone tell me the entomological term for the different types of members of, say, an ant nest - the soldiers, the workers, the queen - they're not separate species, of course; are they separate subspecies? - phenotypes? - breeds? - what's the correct word here? Thanks Adambrowne666 02:42, 23 October 2006 (UTC)

I don't know what they are. But i do know they're not seperate subspecies or breeds. It's not to do with genotype/phenotype either. Insects, especially community insects like bees and ants, commonly have permanent gene loss during development. So your queen and your soldier ant could have almost the same genes, it's just that the soldier ant losses a part of its genome permanently during development. Where as the queen keeps all the genes, obviously...since the queen does the reproducing. I'd assume different 'classes' in a nest are due to different genes lost, since all ants within one nest/community have very similar genetically. --`/aksha 02:55, 23 October 2006 (UTC)

They're called castes. - Nunh-huh 04:02, 23 October 2006 (UTC)

Effectively, they're just different genders. In a honeybee colony for example, the queen is female, the workers are infertile females (they have under developed ovaries, and can't mate, being inhibited by the influence of an existing queen) and the drones are males. The same is true of the ant colony (in this case, queen, worker, soldier respectivally). Martinp23 23:03, 23 October 2006 (UTC)

In fact that's true for bees, but not for ants. There are female and male soldiers, workers etc., but they are all infertile. --84.166.249.224 14:47, 29 October 2006 (UTC)

In case you're interested, there is only one queen in a honeybee colony, and she lays eggs which hatch into workers and drones. The difference between the two eggs is that the worker one is fertilised with sperm from a drone, and the drone egg isn't. Therefore, interestingly, the males have no father in a honeybee colony. To produce a queen, an egg is laid fertilised, like that for a worker, and is fed on an enriched diet of Royal Jelly, allowing her ovaries to fully develop. The queen mates once in her life with around a dozen drones from different colonies (who die after impregnating here) and she stores the sperm for the rest of her life (up to 5 years) within her body. </beekeeping lesson> :) Martinp23 23:03, 23 October 2006 (UTC)

Castes! Of course! Thank you very much. Adambrowne666 23:07, 23 October 2006 (UTC)

how may calories are in... me?

To start.... this is NOT A MEDICAL QUESTION. I do not intend to be eaten or eat myself. I am purely curious about this matter.

I am very curious about how many calories there are in me. I am a 5'1" 140lbs woman with a 32% body fat percentage. (I know, I know, I need to lose weight). This means that my "lean body mass" is appx 96 pounds. It would be easy enough to add together the calories of 96 pounds of say, ham, and 44 pounds of pure fat, but there is the issue of bones, hair, brains, teeth, fingernails etc. I am assuming that my organs will not be eaten (although it would be interesting to find out how many calories are in a human kidney or liver). So is there any way to find out what is the weight of my muscle, or non-soft-tissue? All help is appreciated.

PS: Is it legal to eat myself, say, if I am wearing a mask? What about a red mask? ;) 74.117.47.205 03:20, 23 October 2006 (UTC)

We have a dog and four cats and they seem to be trying (to eat themselves) on a daily basis and without masks. I don't know about the calorie part as they seem to neither lose nor gain weight.  ;-) --hydnjo talk 04:13, 23 October 2006 (UTC) addendum: If you want to do the math, one pound of fat equals about 3500 - 4000 calories (actually it's kilogram calories or kcals) and one pound of muscle (meat) equals about 1600 - 1900 calories (using the same colloquial term). Water makes up a significant part of your body weight (about 70 pounds in your case) so you'll need to subtract that out. Also, so as to confound your calculations even further, your 32% body fat percentage may include some of the water weight as does the muscle (meat) weight. All in all, your body properly preserved and so on. should provide enough sustenance for one person for several weeks however I would suggest including some vegetables and fruits for a balanced diet.  ;-) --hydnjo talk 04:50, 23 October 2006 (UTC)

I'm not sure what you are trying to get at. If all you care about is the total amount of energy within your body then a calorimeter should be used. Ideally, we put you into the "large" calorimeter and burn you alive and measure the total amount of heat release. Short of that, we use a cadevar in a body similar to yours and burn it instead. 202.168.50.40 04:27, 23 October 2006 (UTC)

Do bones have calories? What about hair, cartilage, eyeballs etc? I am not talking about my body as a whole, but rather the parts of my body that a human would consume if he were to eat me. 74.117.47.205 04:34, 23 October 2006 (UTC)

Since you weight 140 lbs, your body mass has about ${\displaystyle 5.70735888\times 10^{18}}$ joules of energy on it (E=mc²), which gives ${\displaystyle 1.36409151\times 10^{15}}$ kcal. Good luck on losing that. :) ☢ Ҡi∊ff⌇↯ 04:31, 23 October 2006 (UTC)

Umm, don't forget to subtract out the water and bone (hair, nails etc). --hydnjo talk 04:55, 23 October 2006 (UTC)

That's if you made her into an atom bomb... --Wirbelwindヴィルヴェルヴィント (talk) 05:23, 23 October 2006 (UTC)

Wow! I sure would like to get the concession rights for that one. Step right up ladies and gentlemen ... --hydnjo talk 05:46, 23 October 2006 (UTC)

Atom bombs work by exploiting the mass defect between different atoms to create its energy. Atom bombs are far less potent than the energy amount quoted above. That amount of energy (e=mc) could only be released if you annihilated every atom (e.g. with an anti-person).Richard B 23:13, 23 October 2006 (UTC)

Fat and muscle contain water, I dare say that the kcals figure quoted above includes that water, it isn't kcals of "dehydrated muscle or fat". So I don't think you subtract the water from the calculations.... As far as "edible" goes, most of the body would be and have some sort of nutricius value, as far as eyeballs, cartilage, kidneys, lungs, brains. About the only thing I think isn't digested is teeth and hair, you'd have trouble eating the bones, but you would digest them, if you were to grind them up for example.Vespine 00:42, 24 October 2006 (UTC)

Feral Horses of the World?

Hi, I've been trying to research feral horse populations, but haven't been able to find many, just the well-known ones. I.E. Sweden's Gotland Pony or North Carolina's Corolla "Wild" Horse/"Banker Horse". (The only true wild horse is the Przewalski's Horse.) Can anyone point me to a good site/book that lists feral horses of the world? If not, could I please put in a request for such an article? Thanks in advance:) —The preceding unsigned comment was added by StandardSmiley (talk • contribs) .

The horse section of feral suggests that there are hardly any real wild horses, so any horses in the wild are likely to be feral. Confusingly, the wild horse article uses the term 'equus ferus'. But I don't really know anything about the subject. I'm just doing your work for you, looking it up in Misplaced Pages. Note, btw, that feral horse simply redirects to 'horse'. As for requesting an article, you can do that at Misplaced Pages:Requested articles. I have never done that, so I don't know how successfull such a request might be. DirkvdM 08:21, 23 October 2006 (UTC)

The confusing thing is that a Latin word meaning "wild beast" has been given a rather more specialized meaning when applied to animals; specifically: domesticated animals having reverted to a "non-domestic lifestyle". Equus ferus is simply classical Latin for "wild horse". When your compatriot Pieter Boddaert introduced the scientific binomial name, the word in English just meant "wild", "savage".  --Lambiam 09:29, 23 October 2006 (UTC)

Chlorinated water and eye damage.

Would my eyes be damaged from exposure to chlorinated water for 20-30 minutes a day? I often swim with my eyes open, and haven't noticed any damage to my sight in the six months I've been swimming, but wanted to make sure. —The preceding unsigned comment was added by 202.10.86.63 (talk • contribs) .

I assume you've read the medical disclaimer, so I'll skip the lecture. Swimming pools are "chlorinated" with hypochlorite salts like sodium hypochlorite (a.k.a. chlorine bleach). A quick search on Google Scholar for cornea hypochlorite damage doesn't turn up anything worrying. It causes "irritation" (duh), but I don't see any mention of long-term damage. —Keenan Pepper 05:03, 23 October 2006 (UTC)

No your eyes will not be damaged. Mine were not and I swam in chlorinated water for dozens of hours each week every summer for a few decades. Eyes open. I loved swimming underwater. Don't do it much anymore, tho. WAS 4.250 16:11, 28 October 2006 (UTC)

Fissile material

After obtaining enough fissile material, what would one need to do to create a crude nuclear bomb (assuming one also had trained nuclear technicians to do so)? Like, what kind of steps would ahve to be taken? For the record, I'm not a terrorist, I'm just writing a thriller for NaNoWriMo. —The preceding unsigned comment was added by 58.7.219.86 (talk • contribs) . 01:17, 23 October 2006 (UTC)

It's not just obtaining the fissile material - it's seperating it from non-fissile material. Fissile uranium and plutonium make up less than 1% of all teh uranium and plutonium in all of nature. So, you have to run it through very long pipes (3 miles or more); the lighter (fissile) material comes out first, and that's what you put in your bomb. The problem is that in order to make it run through the pipes, you have to bond it with flurine to make it Uranium hexafluoride gas. However, Uranium hexafloride is *extremely* corrosive. In early WWII test, it ate through a 3 inch think glass pipe in 10 minutes; and a 3-inch steel pipe in two hours. The next trick: coat the inside of the pipe with Telfon and your corrosion problem is solved (This is why Teflon was a major war secret). After that, it's relatevely easy to build a uranium bomb. A plutonium bomb requires a lot mroe work though. Raul654 06:04, 23 October 2006 (UTC)

That's only if you are trying to enrich the material yourself. No terrorist has the facilities to enrich their own material; they'd either try to buy it or steal it. Both would be somewhat difficult; I'm inclined to think stealing it would be slightly easier though not much (buying it already requires somebody to have access to it and be willing to stake their own life on it, and you also have a high chance of either ripped off by the seller or by accidentally trying to buy it from a CIA agent). --Fastfission 00:36, 24 October 2006 (UTC)

Read the Nuclear weapon article. I'm afraid that's all the help we can provide right now (and it's substantial). I usually don't speak for other users but in this case I'll make an exception; none of us are terrorists. Perhaps you could add your manuscript to Wikibooks as a token of thanks for our research. --hydnjo talk 06:04, 23 October 2006 (UTC)

Yep, and nuclear weapon design. If you've got enough highly enriched uranium, the task is conceptually simple - just slam two bits of it together at a reasonably high speed - the easy way to do this is essentially whack one bit of uranium in a custom-built cannon and have the other bit at the end of the barrel. With a bit of experimentation, I reckon I and the local blokes down at the local welding shop would be able to do that. By contrast, if you're trying to use plutonium, it's a much, much harder task. You need to create a set of explosives that can "pinch" a sphere of plutonium into a super-compressed state, and then just as the compression reaches its maximum release a supply of neutrons that starts the reaction going - if you get the timing of the explosives or the neutrons wrong, you may get no bang at all, or a much smaller one. From the information to hand, it seems like North Korea's nuclear test was just such a "fizzle". --Robert Merkel 06:30, 23 October 2006 (UTC)

In The Fourth Protocol (film), you can see Pierce Brosnan assemble a nuclear bomb. Not too much detail, but it's a good film, so if you might ever want to watch it, now would be a good time. Btw, I like your disclaimer. I wonder what answers you would have gotten if you would have said you were a terrorist, since that would obviously have meant you weren't. Or would it? Let the double guessing begin. :) DirkvdM 08:05, 23 October 2006 (UTC)

Uranium bombs are easier to build - you just fire two sub-criticle masses at eachother, when they are close enough to make a criticle mass they explode, assuming enough neutrons are floating around in the environment. The WWII bomb had a 10% chance (if memory serves) of not working due to a lack of available neutrons.

Plutonium bombs need an initiator to supply a burst of neutrons at the right time to start the reaction (during implosion). The WWII bomb used a Berillium based initiator that is still classified (as of twenty years ago). Modern plutonium bombs use a minuture linear accelerator and target material for the initial neutron burst. Dallas67 10:25, 23 October 2006 (UTC)

The Little Boy gun-device also had neutron initiators. They wouldn't have left anything to such a high chance as 10%. --Fastfission 00:36, 24 October 2006 (UTC)

If you obtain enough fissile material you've gone 90% of the way to making a very crude nuclear weapon — fissile material will be the biggest and most difficult step for any non-state entity. You could create a pretty nasty explosion just by throwing a critical mass together any which way. It might not be on par with a kiloton-range weapon but it would be pretty impressive on a human scale. It really depends what you, the hypothetical user, are going for. If it is just a scary and deadly explosion you can get that without it being elegant from an engineering standpoint. The fancy implosions and all of that are for when you really want to get a VERY big explosion out of it; if you are content with something which is less than a kiloton in yield (which is still very large from a human point of view; the Oklahoma City bombing explosion was only .002 kt in yield) and radiologically messy you can cut a lot of complicated engineering corners. --Fastfission 00:36, 24 October 2006 (UTC)

On a related note: I've heard whispers of the theoretical possibility of a fustion bomb without a fission trigger, relying on super accurate implosion techniques. Does anyone have any information on this? Dallas67 02:11, 24 October 2006 (UTC)

That possiblity is discussed in Induced gamma emission and Sam Cohen and the book Imaginary Weapons. (Hafnium bomb) Current consensus says it doesn't work. --GangofOne 05:16, 24 October 2006 (UTC)

Might I point out that it violates the rules of NaNo to begin research before November starts? :(

Your uranium separation comments suggest that you are talking about the gaseous diffusion method of separating the 235 from 238. That takes a lot of space, money and time. Only nation states have those resources. Terrorists will either 'steal' the 235 or they will buy a flow forming machine and make thier own centrifuges. The centrifuge method of isotope separation is by far the cheapest and most space efficient way to do enrichment. The space aspect is important if you are trying to conceal the fact that you are doing it. The total number of centrifuges needed in a cascade system is dependent on the speed you can obtain with your centrifuges. Really good designers use magnetically levitated cans. Yes, there are tricks but then you would not need to show those on a movie. What you need to concentrate on showing is the fact that the centrifuge method of enrichment has changed the game totally and made terrorist nukes a very real PROBABILITY. They are cheap to build and easy to hide. That is scary! Forget calutrons and gaseous difussion. Today, that would me like using vacuume tubes to build a laptop.

Genetic tendancy towards AIDS amongst Black people?

It seems all statistics show that black people have a greater chance (up to 15 times!) more to get AIDS then a white person of European decent . Is this a genetic tendancy or some other reason? Has there been any scientific studies? —Preceding unsigned comment added by 68.235.225.150 (talk • contribs)

The question is flawed. There is absolutely no genetic basis for AIDS. Raul654 05:59, 23 October 2006 (UTC)

I believe Africans have a high rate of AIDs, did you mean that? See AIDS#Economic_impact and the graph there, for example. But no, AIDS isn't a genetic thing; it has to do with behavior, which might be impacted by upbringing, family, where someone grew up, etc. --Wirbelwindヴィルヴェルヴィント (talk) 06:09, 23 October 2006 (UTC)

I am seeing different responces from different people. It seems most black professors who have studied the subject claim that AIDS is in fact a genetic disease, while white scientists claim that it is not. I haven't been able to find any scientific studies. 68.235.225.150 06:25, 23 October 2006 (UTC)

Indeed. It is probably due to behavior. --Proficient 06:27, 23 October 2006 (UTC)

Okay... just like any disease, there is a genetic component to HIV infection, at least with regards to susceptibility, meaning that there is likely some degree of variation; I recall reading a paper about a number of African women appear to be entirely immune to the disease, probably because they carry a mutation in a gene that affects the expression of the glycoproteins that HIV attaches to. I cannot say whether any particular population is more or less susceptible to HIV infection, (and I have no doubt that the answer is complicated by the fact that the strains of HIV that are prevalent in Africa are not the strains more common to Europe and the Americas) but I would think that someone, somewhere, managed to get grant money for such a study. If you find an answer, let me know. – ClockworkSoul 06:38, 23 October 2006 (UTC)

For a start, i believe the question you're really asking is whether Black people are more suspectible to HIV, the virus which results in the syndrom called "AIDS".

The answer is, yes, black people more commonly get HIV and are more 'suspectible' to AIDS. But it has nothing to do with genes.

Let's start with HIV.

• HIV originated in poor parts of asia/africa area, and didn't enter western society for quite some years. Not surprisingly since people from those poorer parts don't often immigrate to the western world. In other words, HIV has had far longer to spread in africa, where it's all black people.

• no one knew what HIV was at first. When it hit the western world - the western world keeps medical records, has medical databases, has hospitals and doctors and the facilities. When people noticed a how bunch of gay guys suffering from immuno-deficient disorders, they had the resources to investigate. They worked out what it was, what caused it, and how it spread. I'm afraid africa doesn't have those luxuries. Since AIDS is a slow disease (you don't get sick and die immediately from contracting it), AIDS probably existed and had time to spread for ages in africa before it hit the western world and got identified. In africa, HIV has had the chance to integrate into the population so much that children are often born carrying the virus these days (because their mothers do), which further increases the rate of HIV in those countries.

• HIV is spread primarily as a sexually transmitted disease. Condoms are rare in african countries, people do not have a culture of using them. Rape is also common. It's also common for men to have many wives. All these things means VERY easy transmission of HIV. In the western world, people are on average more monogamous (sticking to one sexual partner), condoms are readily avaiable and used.

• HIV is not acute - you get it and have no symptons for ages. In africa, many people probably don't realize it when they contract HIV. In the western world, people can access a doctor very easily. If they just get a little sick, they go see a doctor. Blood tests are easy to do, and experienced doctors will notice the symptons and diagonose quicky. People can then take measures to not spread it. In Africa, people get sick a lot more often, and don't have access to doctors so easily.

• Even in western society, black people are more likely to get HIV. This is because black people tend to be of the poorer, low social-economic class. Poorer means less access to medical facilities. Low social economic class means less education about health, disease, spread of disease, and safe sex in terms of sexually transmitted diseases. Poorer also means living in areas of higher crime, basically meaning more cases of rape and so on. You'll find that black people iin general tend to have more health problems, because they're poor and of low social-economic groups. HIV is not an exception, it's pretty much the norm.

now moving on to aids. HIV can stay in the body for a period of time without causing any harm. Up to about 10 years without medical help. At some point, no one knows what the trigger is, HIV activates and the body starts showing the symptons. These symptons are what's called the "Acquired Immune Deficiency Syndrome" (acquired refering to how AIDS is aquired from the virus HIV). --`/aksha 03:42, 24 October 2006 (UTC)

One tiny point: AIDS is called "acquired" because it's acquired from other people (it's contagious), rather than being genetic. --Tardis 19:13, 23 October 2006 (UTC)

Uhh...isn't it "acquired" as oppossed to cognetial? ...uh...however you spell that word. The one which means you're born with something. --`/aksha 03:42, 24 October 2006 (UTC)

Congenital means, literally, present at birth. Babies with AIDS still "acquired" it; they just did so rather early in life. The opposite here is really genetic, because then it's just that your immune system is inherently broken. Or perhaps it was simply not known that AIDS could be congenital when it was named, since "acquired" and "congenital" usually are opposites in medicine. --Tardis 23:25, 24 October 2006 (UTC)

• Once aids starts to show, people are more or less doomed to die soon. There are drugs to slow this process down, so HIV can lie dormant in the body for a long time and the person will not start to suffer from AIDS. These drugs are expensive - not the kind of thing that's regularly found in Africa. The drugs are also most effective if the person starts taking them as soon as they get HIV. Once again, black people who are of the poor social-economic groups tend not to do this. Some don't realize they have HIV. Others can't afford the drugs. Others simply can't be bothered. Hence the HIV infected black people develope AIDS much more quickly.

"I recall reading a paper about a number of African women appear to be entirely immune to the disease" they're not actually immune. There were reports of people in Africa who seemed to be infected with HIV and just carried it with them all their lives without realizing it. In other words, they lived long (long as in normal age for healthy people in their society) and normal lives despite having the virus. So for whatever unknown reason, despite being infected with HIV, the HIV never really activates in their body. So not exactly immune...more like being sick but just not dying. Which i guess is 'immunity' in one sense of the world. --`/aksha 13:54, 23 October 2006 (UTC)

The term for that is a carrier, with Typhoid Mary being perhaps the most infamous example. Another problem in Africa is the persistent myth that having sex with a virginal woman will cure the man of AIDS, while, in reality, it only spreads AIDS to the woman. Also, women in Africa are so dependent on men for survival that they must do whatever they are told, including having sex without a condom, even knowing that their man sleeps around. StuRat 19:20, 23 October 2006 (UTC)

Um, no there is a genetic component to susceptibility to AIDS. The HIV virus requires several proteins in order to attach to and infect a cell. One of these is the chemokine protein CCR-5. Patients who lack CCR-5 are relatively immune to infection by HIV!

why do i have a feeling that the only way someone can lack CCR-5 is if they don't have a functioning gene for it? --`/aksha 03:42, 24 October 2006 (UTC)

Does the CCR-5 gene do anything useful ? If not, we could wipe out AIDS by creating a virus that destroys that gene, then let the virus go free. StuRat 16:57, 24 October 2006 (UTC)

CCR5 discusses this in come detail. – ClockworkSoul 13:49, 25 October 2006 (UTC)

Come again ? Are those details about how HIV is spread ? :-) StuRat 22:34, 25 October 2006 (UTC)

Gamma rays

Why gamma ray is not a particle but a ray only? It is told that waves also behave as a particle, then why is it not true with gamma ray?

• It's not... Although the name is a bit confusing, gamma rays are simply the highest-energy example of electromagnetic radiation. Their particle is the photon. – ClockworkSoul 07:21, 23 October 2006 (UTC)

Make that the highest-energy range of EM. Just like visible light is an EM range, ranging from red to violet. Gamma rays, however, are not defined to have an upper limit. Something tells me that in reality there is a limit, but the article doesn't seem to say. DirkvdM 07:57, 23 October 2006 (UTC)

Cosmic Rays are supposed to have an even shorter wavelength.

But Cosmic rays are particles. ☢ Ҡi∊ff⌇↯ 15:14, 23 October 2006 (UTC)

At shorter and shorter wavelengths, dont these things appear more like high energy particles. All particles can be considered as waves and vice versa.--Light current 16:08, 23 October 2006 (UTC)

As Feynman said, they're particles, because you can hear the individual clicks they make in a Geiger counter. There's no such thing as half a gamma ray. —Keenan Pepper 19:36, 23 October 2006 (UTC)

But again, there's no such thing as a "particle" when one looks at the proper scale - gamma rays are just very high frequency/short wavelength light (with the attendent wave/particle duality involved). Virogtheconq 04:10, 24 October 2006 (UTC)

Application of Nature Cure for treatment psoriasis

Can you kindly explain whether Naturopathy can be successfully applied in the treatment of psoriasis of skin, where treatment by allopathy, siddhavaidya etc., have not yielded satisfactory results. If so. what are the sources (hospitals etc.,) available in Hyderabad? Regards Chandru —Preceding unsigned comment added by 59.144.66.3 (talk • contribs)

A very natural treatment is by doctor fish. I'm afraid this may not yet be available in Hyderabad.  --Lambiam 08:50, 23 October 2006 (UTC)

Some people have suggested that a change in diet can be helpful. Also, some preliminary evidence exists for positive results from topical application of some botanicals. --JWSchmidt 13:56, 23 October 2006 (UTC)

You are likely to get two very different kinds of answer to a question about naturopathy here, depending on whether the poster believes that naturopathy has any efficacy at all. I suspect that the majority of posters to this reference desk are in the latter group, but I may be wrong. I would not recommend wasting time on it myself. --ColinFine 15:09, 28 October 2006 (UTC)

alluvial sedimentary rock

what is an alluvial sedimentary rock? —Preceding unsigned comment added by Ali khoobani (talk • contribs)

Here "rock" is a mass noun. Alluvial sedimentary rock is an alluvial deposit consisting of rock.  --Lambiam 08:40, 23 October 2006 (UTC)

And I'll say it's a rock composed originally of alluvial deposits. :) --Zeizmic 12:43, 23 October 2006 (UTC)

heat

what generates the heat to melt the rock in the earth core? —Preceding unsigned comment added by Ali khoobani (talk • contribs)

According to the prevailing theory of planetary formation, planets are formed by dust and gas clustering together in increasingly larger clumps, finally collapsing together to form a planet-sized body. The heat generated by the kinetic energy lost in the impacts made the Earth melt. Since then it has only been cooling down. The generally accepted explanation is that the heat is simply left over from the Earth's initial formation; see Structure of the Earth.  --Lambiam 08:33, 23 October 2006 (UTC)

I sure wish I had cared more about global geophysics. Our article seems wrong about the source of heat for the earth. This is more in line with what I understand. --Zeizmic 12:40, 23 October 2006 (UTC)

I agree, the primary source of heat in the earth is radioactive decay. If the earth had no internal heat source it would have cooled down a lot more already. Misplaced Pages does have some articles that mention this - see Geothermal power, Age of the Earth and Uranium. JMiall 12:57, 23 October 2006 (UTC)

This played an interesting role in the history of science. Before radioactivity was understood, people such as Kelvin claimed that their physical science theories for rates of cooling of the Earth and rate of chemical fuel depletion in the Sun showed there had not been enough time for biological evolution to take place on Earth. A good example of why scientific claims should always begin with, "If my assumptions are correct...." --JWSchmidt 13:39, 23 October 2006 (UTC)

What about all the pressure on the earth's core? That's what I always assumed made the nickle and iron in the core liquid. - AMP'd 14:09, 23 October 2006 (UTC)

No, high pressure forces most materials to become solids. This is why the very core of the Earth is thought to be solid, even though the mantle is molten, and the core is even hotter. StuRat 19:01, 23 October 2006 (UTC)

So I had it backwards? - AMP'd 02:20, 24 October 2006 (UTC)

In general, yes, although there are exceptions, as some materials, like water, are actually less dense as a solid. StuRat 16:53, 24 October 2006 (UTC)

Radioactive decay is what generates the heat. since nothing can burn in the conventional sense, this is the only possible answer (I think).--Light current 14:53, 23 October 2006 (UTC)

Also, tidal forces from the Moon and Sun generate some heat in the interior, but likely far less than radioactivity. StuRat 18:57, 23 October 2006 (UTC)

Current researches about earth core neutrinos try to tell the percentage of heat caused by radioactivity. It could be only 30-40%. -- DLL 18:59, 23 October 2006 (UTC)

So what causes the other 60 -70 %?--Light current 00:21, 25 October 2006 (UTC)

I just saw a TV program on the Earth's magnetic field, which claimed the Earth's core is cooling at a rate of about 100 degrees (they didn't specify units) per billion years. How fast the initial heat (created by planet formation) would dissipate without radioactivity and gravitational tides was not exactly clear. When the mantle does solidify, in a few billion years, this will cause the magnetic field to cease, which, in turn, will cause the atmosphere and oceans to be driven off by the solar wind. StuRat 22:31, 25 October 2006 (UTC)

Unidentified Mushrooms

What mushrooms are in this image? It's a very good image, and I would like to put it in the appropriate area, but I don't know what kind of mushroom it is. Chanterelle, maybe? NauticaShades 07:49, 23 October 2006 (UTC)

They certainly look like it. I wouldn't eat them, though, unless they are printed on edible paper. Did you think of asking the photographer and uploader André Karwath aka Aka?  --Lambiam 08:16, 23 October 2006 (UTC)

Oh man, so many witticisms in one reply, I think I'm going into repartory arrest! Anchoress 09:47, 23 October 2006 (UTC)

Google has 280,000 hits for "repertory arrest", and it is my sad duty to report that a lot of them seem to be talking about cessation of breathing, eg. respiratory arrest. JackofOz 09:56, 23 October 2006 (UTC)

Dood, you need to bone up on your ironical vocab. I meant repArtory as a mangling of 'repartee'. I assure you that clever word play is not sufficient to induce respiratory arrest, in me anyway. ;-) Anchoress 10:19, 23 October 2006 (UTC)

Oh, I detected the irony and the humour alright, although I admit I thought it was a mangling of "repErtory" rather than of "repartee". What's it called when you laugh at a joke for completely the wrong reason? Dorkness, maybe? But I don't think it matters as long as you're having jolly fun with your chums. Anyway, we've discovered a further reason to be cautious when a doctor uses big words.  :-) JackofOz 19:58, 23 October 2006 (UTC)

I love collecting edible mushrooms, but that looks like a pile of several types. --Zeizmic 12:25, 23 October 2006 (UTC)

Looks like chanterelles to me. I wouldn't worry too much about eating them myself. I've heard more than one mycologist say that chanterelles don't resemble any poisonous fungi. (And are therefore recommended to inexperienced mushroom-pickers). --83.145.46.141 13:53, 23 October 2006 (UTC)

Um, ah, well, it all depends where you live. If you happen to live somewhere that the Jack o'lantern mushroom grows (and glows), you can make yourself sick as hell if you confuse the two pretty orange mushrooms. We really oughta give the same disclaimer for mycology here that we do for medical and legal advice... --jpgordon 17:17, 23 October 2006 (UTC)

They do look a lot like chanterelles, and the fact that someone bothered to pick and dry a whole pile of them does suggest that they might be an edible species. Of course, I'm saying this safe in the knowledge that I won't be eating those particular mushrooms. Still, I'd find the identification sufficiently plausible for adding something suitably equivocal, like "probably chanterelles", to the image description, especially since correctly identifying dried mushrooms by sight is generally much less safety-critical than identifying fresh ones — dried fungi, if you didn't dry them yourself, usually tend to come pre-labelled. (And yes, jpgordon's point is important — just because a particular edible species looks like nothing else that grows near you doesn't mean there isn't a poisonous look-alike growing in some other part of the world.) —Ilmari Karonen (talk) 14:56, 27 October 2006 (UTC)

Chemistry/ Heat curves

How much energy (kj) is required to convert a 15.5 g ice cube at -5.0 to water vapor at 180 degrees Celsius?

Yeah, I had those questions in school too. You'll want to divide the problem into a few steps:

1. Heating the ice to the temperature where it can melt
2. Melting the ice
3. Heating the water to the temperature where it can evaporate
4. Vaporising the water
5. Heating the vapour to the final temperature

—Bromskloss 13:15, 23 October 2006 (UTC)

Sodium Dodecyl Sulfate

I did a Chemical Engineering lab last week to investigate the surface tensions of various concentrations of solutions of sodium dodecyl sulfate, also known as sodium lauryl sulfate. One of the aims was to discover the maximum surface concentration at the liquid/gas interface, and the minimal area of a molecule of said compound. This was done using the maximum slope of a plot of surface tension against log of concentration. Does anybody know the correct value for either of these, so I can analyse the accuracy of my results in my lab report? I only need one correct value because there is a simple relationship between the two. I already tried to google it but no luck, and I can't access the library at the moment.

Thanks! 7Munkys 13:07, 23 October 2006 (UTC)

Bad horror-movie bacteria!

How the hell do you kill these things??? Just reading the article is personally scaring the crap out of me! I mean, it can take heat, cold, vacuum, radiation, dehydration, even acid! Do you lock them up in jar and watch them starve them over three years? Do you try to poke it with a sharp stick? What? I really want to know! I need to be able to sleep at night! 83.250.208.83 14:57, 23 October 2006 (UTC)

Just put it in the oven and bake it for a few hours at 300 degrees Celsius. I'm sure it can't take that much heat. --Bowlhover 15:34, 23 October 2006 (UTC)

I'd prefer a plasma arc, if in fact, those things actually exist! --Zeizmic 15:46, 23 October 2006 (UTC)

One should consider whether it is, in fact, pathogenic before getting worried about them. Also, just because it is an extremophile doesn't mean it will flourish in normal environmental conditions, given that it is suddenly confronted with both competition and predators. —The preceding unsigned comment was added by 192.91.171.42 (talk • contribs) .

Exactly. They're probably harmless to humans. And Strain 121 can kick their asses anyway. =P —Keenan Pepper 19:45, 23 October 2006 (UTC)

Don't waste time; break out the phasers and photon torpedoes. B00P 20:38, 23 October 2006 (UTC)

Being extremophilic, I doubt they've had much experience of antibiotics, so a good dose of those could probably kill it. Laïka 21:37, 23 October 2006 (UTC)

If you're afraid of foreign creatures which can stand high temperatures, does that make you an xenophobic in regards to extremophilics? --Fastfission 00:23, 24 October 2006 (UTC)

Very cool - are there other bacteria like these two? Aaadddaaammm 03:38, 24 October 2006 (UTC)

Lots of weird extremophiles are being discovered . Also, do you know the Archaea story? In 1977, biologist Carl Woese was working with bacterial cultures from deep underground when he discovered that they were not bacteria, with the result that today we say there are three types of life forms: prokaryotes (bacteria,) eukaryotes (protists, plants, animals,) and Carl Woese's archaea. Here's another: biologist Lynn Margulis proposes that all natural deposits of mineral ore are actually created by chemosynthetic deep-rock bacteria/archaea where different species metabolize each dissolved mineral from ground water while depositing the insoluable ore. Ever wonder why are there mines? It's because the Earth is like blue cheese! More like copper cheese, molybdenum cheese, etc. (Does this mean that we could pump seawater through bacterially-contaminated hot wet sand and later extract gold or platinum? Or how about Uranium?) --Wjbeaty 02:11, 25 October 2006 (UTC)

That's some pretty cool bacteria. --Proficient 02:30, 26 October 2006 (UTC)

Reishi and Birth Control Pills

Dear Misplaced Pages:

Good Day! My wife is taking some birth control pills but she's also taking some reishi mushroom for her health. Does reishi can hinder the effect of pills?

Thanks> Gerry

Please read the rules. "If requesting medical or legal advice, please consider asking a doctor or lawyer instead.--Russoc4 16:21, 23 October 2006 (UTC)

You could also ask your pharmacist. Make sure you can specify the specific pills used.  --Lambiam 16:25, 23 October 2006 (UTC)

The pill can be made ineffective if you experience vomiting or diarrhoea and this mushroom seems to have symptoms of gut clearing, so I would definitely check with a professional. Vespine 23:07, 23 October 2006 (UTC)

watershed management

how can watershed management be done? can you give an example of a place where this is being implemented?61.246.87.148 16:51, 23 October 2006 (UTC)abcd

I'm not sure what you mean. Do you mean management to prevent floods, to limit soil run-off, prevent water pollution, reserviors for irrigation and human consumption, sewage treatment, hydroelectric generation, etc. ? :-) StuRat 18:41, 23 October 2006 (UTC)

...or trying to get your kids to bed by 9pm?--Shantavira 08:48, 24 October 2006 (UTC)

Make sure they pee before turning in, or the bed could become a water shed. :-) StuRat 20:00, 24 October 2006 (UTC)

Alpha Helix

I am trying to do a quesstion for an university assignement and after looking through 3 text books, I am still puzzled. The question is as follows:

"The peptide chain below folds into an alpha helix. /an alpha helix is 0.54 nm long (5.4 Angstrom units) for every complete turn, and there are 3.6 amino acid residues per turn of the helix.

Lys pro val leu gly ala Ile ala asp leu val val gly leu glu ile leu ala val ala gly tyr ser"

I know this is kidna a homework question but I am officially stumped.

I am also to describe the nature of the protein (i.e. polar, non-polar, predominantly charged)

and finally,

If the hydrocarbon core of biological membranes is approximately 30 Angstroms, suggest a plausable function for the peptide.

Was there supposed to be a question already before you came to "I am also to"? If so, I couldn't find it! —Bromskloss 18:33, 23 October 2006 (UTC)

I apologise, it says I am to calculate the length of the helix. I got 3.45 nm.

• You might find it useful to read this article. It has more detail than do Misplaced Pages articles such as this one about how to make guesses about the functions of alpha helical domains.--JWSchmidt 22:14, 23 October 2006 (UTC)

You might want to visit the amino acid article and take a look at each individual amino acid in the peptide. Make a list of the charge and polar nature of each residue. For instance, the first residue is charged and polar. Look at the second residue very closely, as it will do something weird to the helix. Also, you basically answered one of your questions yourself: put the membrane thickness and helix length into the same units, and you might see a similarity.Tuckerekcut 23:07, 23 October 2006 (UTC)

Black Engineers

Hello. I was wondering, where could I find an article or a list of African American Mechanical Engineers? I searched this topic 3-4 times before, but couldn't find anything specific. Thank you for your time.

Thank you,
A Troubled User

See Category:African American inventors. StuRat 21:12, 23 October 2006 (UTC)

Crucell

Hie I am a wondering if you could possibly put up the Crucell's profile on wikipedia. Crucell is a leading Dutch Biotech company based in the city of Leiden. I am a press officer at Crucell so should you need some help compiling the profile, please feel to contact me on email removed

Thanks for the good work

Best regards

Bruce

We want money! --Zeizmic 21:20, 23 October 2006 (UTC)  :)

Of course, Misplaced Pages does not change editorial standards for pay. A good spot to list this would be Misplaced Pages:Requested articles. Standards for the inclusion of a corporation are noted at WP:CORP. Cheers, --TeaDrinker 23:12, 23 October 2006 (UTC)

a) That sounds like advertising, b) This isn't the request section, and c) I removed your email as per policy at the help desk. --Wirbelwindヴィルヴェルヴィント (talk) 23:14, 23 October 2006 (UTC)

C'mon, guys! That was unnecessarily rude and in bad faith. A simple Google search in Misplaced Pages shows that we already have 20 references to this company - among them the fact that they're part of the AMX index. So they clearly meet our WP:CORP criterium. — Sebastian (talk) 20:48, 25 October 2006 (UTC)

OK, I created the article: Crucell. — Sebastian (talk) 23:37, 25 October 2006 (UTC)

Algorithms

Just as articles need to be factual and accurate and subject to correction so do algorithms. So as not to break with the tradition of making encyclopedic articles as esoteric as possible is there an alternate place to post scientific and mathematical algorithms within the Misplaced Pages? Adaptron 21:38, 23 October 2006 (UTC)

Try Wikibooks. --JWSchmidt 22:19, 23 October 2006 (UTC)

Some can be posted here, like common sort algorithms. What does your do ? StuRat 23:13, 23 October 2006 (UTC)

I have many algorithms I am interested in posting but the current one involves the computation of sunset and sunrise from latitude and longitude. Except for one freely available from an online magazine I have yet to find any that are complete and error free. With a place set aside in the Misplaced Pages for publishing such algorithms I would hope such incompleteness or error would soon be eliminated. Adaptron 23:18, 23 October 2006 (UTC)

You've got a good idea for a new wiki there (WikiCode ?). I could post a few myself. What does everyone else think ? StuRat 23:39, 23 October 2006 (UTC)

If it doesn't belong in either WikiBooks or WikiSource, I would definitely be behind such an idea. It's a pity the Wikimedia Wiki-creation process is in a state of flux, or I'd suggest putting a proposal up right away. Confusing Manifestation 02:10, 24 October 2006 (UTC)

Here is a sunup/sundown computational algorithm in need of new wheels and a fresh coat of paint which it might acquire if left in a wiki instead of parked on the street.

Starting with the number of days since Nov. 17, 1858 or a modified Julian date of

JD = 2454032.24616, a computed event (sun up or down) set to UT = 0 or noon and an

estimated event set to UTO = 6 an iteneration is begun to compute the actual value

of UT.

(Note: addition of functions to convert degrees to radians may be necessary)

'initial values

Lat = latitude

lon = longitude

PI = 4 * Atn(1)

HORIZON = -50 / 60

while (abs(UT-UTO) > .0008

'compute the number of centuries since the epoch of Jan. 0, 2000.

T = (JD + UT / 24 - 2451545#) / 36525#

'compute the solar mean longitude

l = 280.46 + 36000.77 * T

'Compute the solar mean anomaly in degrees.

G = 357.528 + 35999.05 * T

'Compute the ecliptic longitude in degrees.

M = l + 1.915 * Sin(G) + 0.02 * Sin(2 * G)

'Compute the obliquity of the ecliptic in degrees.

E = 23.4393 - 0.013 * T

'Compute the equation of time.

ET = -1.915 * Sin(G) - 0.02 * Sin(2 * G) + 2.455 * Sin(2 * M) - 0.053 * Sin(4 * M)

'Compute the Greenwich Hour Angle in degrees.

GHA = 15 * UT - 180 + ET

'Compute the sun's declination in degrees.

DEC = arcsin(-Sin(E) * Sin(M))

'Compute the hour-angle at UT (the current estimate)

HA = arccos((Sin(HORIZON) - (Sin(Lat) * Sin(DEC)) / (Cos(Lat) * Cos(DEC))))

'Compute the time of sunrise, sunset, or twilight.

'RISESET is +1.0 for morning (rising) and -1.0 for evening (setting).

RISESET = 1#

UT = UT0 - (GHA + lon + (RISESET * HA)) / 15#

'The result is in hours.

'Continue until the UT and UT0 estimates are close together.

Wend

'print the computed event time.

print UT

Adaptron 08:42, 24 October 2006 (UTC)

Rate of lunar transit

What is the calculation or rate at which the moon 'crosses' the night sky? In other words, if you were watching a shadow on the ground cast purely by the moon's reflection, is there a calculable rate to ascertain how long it would take to travel an inch, or a foot?

The moon or a shadow cast by it is easier to imagine travelling in degrees, not feet or inches. Imagine a big tree and a little fence post, in one night the tree's shadow may travel dozens of feet while the fence post's only looks like it moves a couple of feet, the commonality is that both shadows travel the same number of degrees. The shadows turn, like the hands of a clock.

Obviously the 'turning' is caused by the earth spinning on its axis. The earth spins fully around once every 24 hours, meaning the moon looks like it is travelling 360 degrees every 24 hours, or 15 degrees an hour, (ignoring the much longer monthly period of the moon). If you do include the monthly revolution of the moon around the earth, it actually adds up, the moon travels forward by an extra 28th of a full revolution every day, or about 13 degrees, which is almost one hour, so every day the moon is almost an hour earlier.Vespine 22:47, 23 October 2006 (UTC)

Dear Vespine: Dynamite answer, in every fashion -- I'm very grateful for your help. Wolfgangus 01:17, 24 October 2006 (UTC)

I think the Moon lags behind the Sun; while it apparently travels from East to West like the Sun, it does so more slowly. See the picture at Lunar phase. This also explains why the path of the Moon's shadow during a solar eclipse travels West to East; see e.g. the animation at Solar eclipse of 2006 March 29. So "Moon rise" is a bit later each day. Using the value of 29.5 days for the synodic month, so that we have on the average 29.5−1 = 28.5 Moon rises in that period, the time from Moon rise to Moon rise is (29.5/28.5) × 24 hrs = 24.8 hrs = 24 hrs 50 mins. The overhead Moon traces out 360° in that period, which amounts to about 14°/hr = 0.25 rad/hr.  --Lambiam 06:49, 24 October 2006 (UTC)

Dear Lambiam: Thank you so much for the valued additional input. Now, if I may ask a question that perhaps begs the obvious: with all this in mind, does the Moon have a verified annual apsis and periapsis with the Earth? If so, how is it calculated?Wolfgangus 09:18, 24 October 2006 (UTC)

It has a perigee and apogee. I imagine this will be calculated assuming the Moon's orbit is a perturbed ellipse. Typical values for perigee is ~363000 km, and for apogee ~406000 km. Richard B 11:31, 24 October 2006 (UTC)

After edit conflict:

Stuff like this can even affect politics. After the Venezuelan coup attempt of 2002, there was controversy over when certain footage was shot. The Revolution Will Not Be Televised (documentary) had the shadows cast differently from another shot, so the argument was used that they were shot during different parts of the day. But how far apart those images were in time depends on the size of the building that cast the shadow. If cast by a tall building, the shadow would move very fast. DirkvdM 09:22, 24 October 2006 (UTC)

Sometimes I have my doubts about the relative 'greatness' of the internet, but this brief forum alone merits its tremendous caliber. Thanks so much to everyone for your help.Wolfgangus 22:47, 24 October 2006 (UTC)

Abnormal waves and tides

Is tidal data from ocean buoys available for download online? Adaptron 22:02, 23 October 2006 (UTC)

I don't think marine buoys are an effective means of measuring tide (which is an interaction with the shore). Other bouy data (NOAA data) can be obtained from the National Buoy Data Center. For tide information, you might try tides online (another NOAA service). --TeaDrinker 23:07, 23 October 2006 (UTC)

Sorry I meant ocean height (to include wave action) which includes changes caused by tides whether at the shore line or offshore. What I am ultimately after are the Fourier coefficients for all locations of measurement, either offshore or at the shoreline. Adaptron 23:28, 23 October 2006 (UTC)

Found it at harmonic_cons_defs Adaptron 23:42, 23 October 2006 (UTC)

October 24

Ivan Pavlov's Insomnia cure

Hello to all, I wanted to know about Ivan Pavlov's Insomnia condition, so far by other researches I found he developed some recipies or prescrpitions for his own condition, this help him to develope a new category of insomnia, is there anyone able to provide me with info about this prescriptios or recipies for insomnia treatment????

Sergio Mexico City

I'm drooling in anticipation of the answer. :-) StuRat 03:25, 24 October 2006 (UTC)

Beer, wine, or something else?

Would an alcoholic beverage fermented from coffee be considered a beer or a wine? I would intuitively say "beer", but I can't give a good reason for it. Does anyone know if such a drink exists? Bhumiya (said/done) 01:25, 24 October 2006 (UTC)

Coffee does not have (or has negligible amounts) of carbohydrates in it, so there's nothing to ferment into alcohol. --Pyroclastic 01:44, 24 October 2006 (UTC)

You can, however, get coffee stout :) GeeJo ⁄_(c) • 01:46, 24 October 2006 (UTC)

That stuff is God-awful. StuRat 03:22, 24 October 2006 (UTC)

Heresy! Respect the Gods X (SUPERDESK|Help me improve) 07:38, 24 October 2006 (UTC)

It is not uncommon to add flavours to alcoholic beverages, so why not coffee? (Apart from the fact that it might taste horrible.) Whether it is called beer or wine depends on what the basic ingredient is - grain or fruit, although the distinction is a bit blurred (and grain is actually a fruit). Note that if you add fruit to beer it's still beer, like with kriek. DirkvdM 09:33, 24 October 2006 (UTC)

I believe it's called Kahlúa, but that's not fermented from the coffee, just flavored with it.

Atlant 17:00, 24 October 2006 (UTC)

And there are drinks like Irish coffee which have alcohol and taste like coffee. But no, I don't think you can ferment coffee. Maybe if it wasn't dried and roasted and sat after harvesting in a vat for awhile? Then that might not taste the same as coffee at all. --Wirbelwindヴィルヴェルヴィント (talk) 17:51, 24 October 2006 (UTC)

Wet coffee grounds definitely mold, but the fluid that runs off is sure nothing I would ever choose to drink. StuRat 19:45, 24 October 2006 (UTC)

I was thinking more along the lines of fermenting the brewed beverage itself after the addition of sugar and yeast. I think it would turn into something resembling a wine, but I don't know how the caffeine and acid would affect the fermentation. Perhaps this calls for an experiment. Bhumiya (said/done) 01:31, 25 October 2006 (UTC)

Beware, experimental fermented beverages can be poisonous. StuRat 03:43, 25 October 2006 (UTC)

Of course they are, that is what we ferment them for. DirkvdM 07:26, 25 October 2006 (UTC)

I doubt simple fermentation of sugar would be likely to produce anything poisonous. My brother and I once did the same thing with sweet tea. Distillation, on the other hand... Bhumiya (said/done) 00:51, 26 October 2006 (UTC)

The distinct coffee flavour is largely due to the roasting, so indeed, it would taste nothing like coffee. I tasted a raw coffee been once and it made me wonder how people came up with the idea of coffee in the first place. Maybe from a burned bush? DirkvdM 07:26, 25 October 2006 (UTC)

I once bought some caffeine gum, to keep me awake while driving. They apparently just filled it with powdered coffee grounds, and it tasted like it, too. Yuk ! StuRat 22:09, 25 October 2006 (UTC)

Bugs Bunny and shotguns

Having learned virtually everything I've ever needed to know from Warner Bros. cartoons, I was wondering about an effect ol' Bugs pulls off occasionally. If you were to jam your finger(s) into the barrel(s) of a firearm, would they cause the gun to be destroyed? Would the force be directed backwards or would you still get killed? Not that I'm planning on trying this at home or anything (I assume you'd lose your fingers and I need to count for a living), but you never know what places life will take you and I'd rather lose two fingers than, say, my head. There's some neat stuff at Physics of firearms about guns exploding by being fired underwater, but that's not quite the same thing. Matt Deres 02:45, 24 October 2006 (UTC)

I would think this might work on a cheap gun, like the proverbial Saturday night special, which has a weak, thin barrel incapable of handling the additional back pressure. The fingers and hand of the person plugging the gun would definitely be destroyed in any event, and the shards of the exploding gun barrel might hit him, as well. StuRat 03:09, 24 October 2006 (UTC)

MythBusters covered this in Season 3, see "Finger in a Barrel". --Canley 03:49, 24 October 2006 (UTC)

Basically, in that episode of Mythbusters, the dummy was killed (or would have been killed if it was a real person) when the gun fired. There was absolutely no damage whatsoever to the gun. The mythbusters even tried sealing off the barrel by soldering a large, iron cylinder into it. This time the barrel peeled back, but the cylinder was still fired out at a lethal speed. --Bowlhover 04:05, 24 October 2006 (UTC)

Right, but they probably used a decent gun. If you start with such a piece of junk that it's almost ready to explode on it's own, it doesn't take much to make it happen. StuRat 16:40, 24 October 2006 (UTC)

If you need your fingers to count, I would suggest abstaining from experiments with firearms. Or using Warner Bros. cartoons as a physics reference. And yes, your head is more important. - Samsara (talk • contribs) 09:21, 24 October 2006 (UTC)

One could just switch to octal, at least for the first two experiments.

Atlant 17:04, 24 October 2006 (UTC)

About the practical side of this. Just in case I'd ever come eye to eye with someone pointing a gun at me (however unlikely), if I could get my hand come close enough to the gun to put my finger in the barrel, that is not what I would do. I'd push the gun aside, possibly even take it from the gunowner. Faster, safer and more effective. Sorry to spoil this academic discussion with practical considerations. :) DirkvdM 09:42, 24 October 2006 (UTC)

I would stay away from the bunny, and go with the coyote! --Zeizmic 16:54, 24 October 2006 (UTC)

Relativity Paradox

I don't have much time to type this in but here is a quick and dirty relativity paradox.

Imagine a small black hole (in 2D space) with a circular event horizon with a radius of 1km. Therefore the circumference of the event horizon is 3.1416 * 2 * 1km = 6.28km

Now imagine a 10km (rest length) train travelling at near the speed of light entering the event horizon and going round and round in the event horizon. Because of the lorentz contraction, the 10km train is contracted to 5km so it would fit in the event horizon.

This is ridiculous that a 10km train can fit in a circular 6.28km event horizon "train track". What happens when the train slows down? The head of the train will crash into the tail of the train. Ridiculous!!! 202.168.50.40 02:53, 24 October 2006 (UTC)

I think I'm missing something, or the above is a little poorly explained. I don't quite see what the black hole is for in this example, why not just say a train track with a radius of 1km? And is the train crashing into its own tail really that ridiculous? Vespine 03:47, 24 October 2006 (UTC)

Why is it ridiculous for a train's head to collide with its tail? It's possible, isn't it?

Also, when the head of the train stops, the end of the train won't know about it until at least 33 microseconds later (10 km/299 792.458). (The real value is much longer, because the information actually travels at the speed of sound.) So for the first 33 micro-seconds, the end of the train would travel in exactly the same way as it used to. This will compress the train, squashing its unfortunate occupants to death... --Bowlhover 04:00, 24 October 2006 (UTC)

The train does not need to stop instantaneously. It can very very slowly slow down. Also, I put in the black hole to prevent the need for the train to exert a constant force, to cause a change in the velocity vector needed to get the train to go around an actual train track. 202.168.50.40 05:16, 24 October 2006 (UTC)

• Doesn't the black hole prevent the train from slowing down? - Mgm| 08:01, 24 October 2006 (UTC)

Also, it'd be unable to support itself in orbit at the event horizon - it'd end up in the sigularity - and if you were looking from far outside the event horizon, you wouldn't observe the train crossing the event horizon - you'd probably just see it increasingly redshifted. Richard B 12:13, 24 October 2006 (UTC)

I'm not sure this problem is well-posed, or is a paradox, but if we're going to bring black holes into the matter remember that in GR geometry isn't what you're used to. For instance, I believe (although I might have it backwards) that the circumference as measured by a (stationary) measuring tape at the event horizon is in fact greater than ${\displaystyle 2\pi r}$, where r is the radius of the black hole as measured by a distant observer. (This means that the distant observer describes the tape as being length-contracted even though it's not moving!) It only gets weirder if you allow the tape (or the train) to fall into the event horizon... --Tardis 15:45, 24 October 2006 (UTC)

You cant go round ad round in the event horizon. You are either inside it or outside it. If inside you wlii eventually rech the singularity. Isuppose you could orbit around safely if outside it--Light current 15:57, 24 October 2006 (UTC)

This must be some new meaning of "safely" with which I'm unfamiliar. (Apologies to D. Adams.) --Trovatore 19:42, 24 October 2006 (UTC)

What do you mean? THat you cant orbit around a BH safely?--Light current 22:30, 26 October 2006 (UTC)

Smoking Question

Disclaimer: I am writing a novel! Be assured I have no intention of forcing this upon a real human being or doing it to myself. The situation is that, due to a horrible trauma in one of my main character's pasts, he's decided he deserves to be punished. He's mentally unstable, and has OCD. He's afraid to die, because he'll have to face the person he harmed. So his punishment of choice is to smoke a certain number of cigarettes(thank the OCD...I don't know the number yet, but let's say 5) in a 30-minute(or so) period, then go without for 7.5 hours(somewhere around there), then repeat over and over. He's been doing this(or somethign similar) for 7-8 years. My question is, what would this feel like? I've gotten some descriptions of withdrawal from smoker friends, but none of them have any idea if this would feel the same way or not. Thanks for helping! Tigger89 03:18, 24 October 2006 (UTC)

If your main character doesn't get lung cancer, it'll likely feel pretty good to be addicted. Quitting smoking permanently is hard. But quitting for 7,5 hours--that should be pretty easy. --Bowlhover 03:44, 24 October 2006 (UTC)

I can share with you my experience, but you're really not specific enough so I'm not sure if I can answer it correctly. I smoked for about 6 years, when I used to drink or played pool, I sometimes smoked a lot, not quite chain smoking 5 in 30 minutes, but maybe half a pack in an hour or two. However, keep in mind that I also more or less quit cold turkey. And I didn't smoke hourly etc, so it fits your character fairly well. From my personal experience, no, the withdrawal isn't stronger in between the binges, so to speak, even after 5-6 years. However, I also smoke slower, 7-9 minutes for a cigarette, I think, so I definately couldn't smoke 5 in 30 minutes. So it shouldn't be any different than the withdrawal from a normal smoker, but that's just from my personal experiences.

However, I just have one question. Why is a person who's afraid to die smoking 3/4 of a pack a day? --Wirbelwindヴィルヴェルヴィント (talk) 03:47, 24 October 2006 (UTC)

The 3/4 pack a day thing...I really don't know, but I just know that's what he does. He started it when he was 15~, so maybe being a messed up teenager had something to do with it? Tigger89 04:27, 24 October 2006 (UTC)

• Talk about unstable. If he's afraid of dying, he shouldn't be smoking that much. - Mgm| 07:59, 24 October 2006 (UTC)

If you use 5 cigarettes in 30 minutes, as Wirbelwind hinted at, for 30 minutes this character will be a furious smoker, almost cartoonishly so. The 8 or so hours between these tar-manias will be immaterial vis-a-vis withdrawal symptoms. From personal experience, I would say physical withdrawal symptoms don't begin for about 24 hours. Cravings in those 24 hours, yes; but true physical withdrawals beyond mental cravings, no. Additionally, chain-smoking in that way is one way to really punish your lungs, meaning when you tie together a string of cigarettes, you feel a unique, rather nasty congestion in your chest, as well as in your mouth. This character's hands will certainly stink (perhaps only an OCD hand-washer could rinse the stench off), and he should have brown, distinct stains where he holds the cigarette -- an often telltale sign in World War Two that a man was a spy; only they had access to enough cigarettes to put stains on the fingers.Wolfgangus 09:34, 24 October 2006 (UTC)

Defibrillator voltage, intensity and energy?

I have read so far the defibrillator article at Misplaced Pages but i am still unable to understand

• why doctors use the term Joule (as energy) in the sense to give to the patient an electrical discharge instead of using more appropiate electrical terms such as volts or intensity?
• What is the relationship of energy (joule) to volts and amperes given to the patient?.
• What are the maximum and minimum volts and amperes (intensity) reached by a defibrillator?
• Can a defibrillator be used to charge (electrically speaking) an car's uncharged battery?--HappyApple 03:38, 24 October 2006 (UTC)

Joule as you correctly identified is a measure of energy, neither electrical term such as volts or current. The relationship is V x I = P: Volts times Amps equals Watts. Watts are a measure of power, while energy is power applied over time. i.e. Joules = (Watts) x (seconds).

The maximum volts and amperes reached by a defibrillator seems not to be common knowledge, it is mentioned in the article that electrical burns are possible from insufficient contact with the electrodes so that suggest that the power is significant, since this power is achieved through capacitors it also suggest that the discharge is rather quick, which would also suggest that a defibrillator would not make a good car battery charger. A car battery requires a long slow low current charge, the defibrillator does the exact opposite..Vespine 04:44, 24 October 2006 (UTC)

Our Defibrillator page doesn't seem to have this info:( For some detail, check the inforesearchtizement for one manufacturer's equipment. DMacks 05:34, 24 October 2006 (UTC)

Ooo, if poor contact causes burns, what happens when there is good contact? Doesn't the heat just get produced in some other part of the body? —Bromskloss 07:42, 24 October 2006 (UTC)

Yes the heat gets produced in some other part of the body, but when the contact is good, the same amount heat is spread out over a much larger area and isn't enough to cause burns.Vespine 14:33, 24 October 2006 (UTC)

Also, there should less resistence if there is good contact. Therefore, the total heat produced should be reduced dramatically. StuRat 16:36, 24 October 2006 (UTC)

If the defibrillator delivers its full payload of energy under all conditions, then under all conditions n Joules (watt-seconds) of energy are deposited in the recipient's body. But with good contact, it isn't all dumped at the very surface of the skin, heating the skin to the burning point. Instead, it's much more-uniformly dissipated throughout the entire conduction path where the overall heating effect amounts to practically nothing. (4.185 joules of energy will heat one gram of water one degree C, so you can see that the overall heating effect of the impulse is pretty small, even at, say, 200 W-S.)

Atlant 17:11, 24 October 2006 (UTC)

If I have time tomorrow and no one else has answered definately, I'll look at it. But I found the 2005 American Heart Association Guidelines. From skimming, the human body is about 80 ohms, studies show that 30-40 A is probably optimal. The defibrillator resistance is around 50 ohms, and that's all I saw. I'll look at it more tomorrow. --Wirbelwindヴィルヴェルヴィント (talk) 08:22, 24 October 2006 (UTC)

Volts are the same as the unit Joules per coulomb. Amperes are the same as coulombs per second Richard B 11:18, 24 October 2006 (UTC)

enzymes

How many enzymes are needed for a human to stay alive. If memory serves me right, it is 500. I don't know for sure, though. --JDitto 04:06, 24 October 2006 (UTC)

I've never heard an estimate, but it would depend on how you classify enzymes. For example, do you count PKA as a single enzyme or a family of them? How about the PKCs? CaMKs? Hemoglobins? Acetylcholine receptors? You get the idea. --David Iberri (talk) 04:54, 24 October 2006 (UTC)

One list of enzymes is available at Misplaced Pages:MeSH_D08. --Arcadian 05:58, 24 October 2006 (UTC)

• When you take into account the amount of enzymes you need for even a single step in some cell transport processes, I find it hard to believe 500 is enough. I think it's far more, but I can't give a definitive number. - Mgm| 07:58, 24 October 2006 (UTC)

So there's no definite list? Oh, man I don't think I have the time to count them all... --JDitto 22:46, 24 October 2006 (UTC)

From the enzyme article: Enzymes are known to catalyze about 4,000 biochemical reactions.. Of course, many enzymes participate in multiple reactions, but the 500 number still seems quite low. Has anybody thought to look at list of enzymes and/or Category:Enzymes? – ClockworkSoul 13:43, 25 October 2006 (UTC)

Why Does My Wife Kill Battery-Powered Wristwatches and Computer Hard Drives?

My wife kills battery-powered wristwatches in one to six weeks. We tried 8 different brands. She kills computers in three weeks to four months of daily use. She has done this for the last thirty years. We experimented with a wristwatch that had died and which began running again when she took it off. It quit working immediately upon being placed on her skin. The watch quit running a few seconds after being placed against her clothing. The watch began running again when it was placed more than eighteen inches from her body. My wife's cousin knew another lady who killed battery-powered wristwatches in a few weeks. In a medical test for metals retained in the body performed about 10 years ago, my wife tested perfectly metal-free. I had aluminum and copper and mercury and magnesium. Might this datum be related to her watch-killing phenomenon? Is watch-killing a common phenomenon? Is this related to a person's EM field? Can this watch-killing emanation be neutralized by some electronic device, similar to how sound waves can be neutralized with an electronic device? Does this watch-killing emanation have other aspects? What other methods might be used to neutralize this emanation? Would this emanation seem to be harmful to other people? Please comment. Marlin

That sounds really really odd. Though humans do generate an EM field (as do all living things), it's not very strong - certainly not strong enough to cause electrical interference (the body will couple with antennas, but that's an unrelated phenomenon). This seems more like a cause of really really bad luck, or something. I've actually never heard of such a phenomenon before, other than apocryphal bad-luck stories. Virogtheconq 06:00, 24 October 2006 (UTC)

At some point, you have to ask which is more painful to replace :).--Tbeatty 06:07, 24 October 2006 (UTC)

I used to wear my father's presumed dead pocket watch during carnaval. To my surprise it started running again, and accurately at that. After carnaval it died again, to be revived again next carnaval. Of course, that's a matter of moving the watch about, and actually the opposite of what your wife experiences, so this story is probably not relevant here. Sorry about that. :) DirkvdM 09:51, 24 October 2006 (UTC)

And now for something more relevant. Does the computer's hardware die (and which bit then?), or the OS? Does she install all sorts of stuff on it? If it's a hardware thing it might possibly be static discharge. Does she wear clothes that 'charge her up'? Do you get a discharge when you touch her? (No, I don't mean that.) DirkvdM 09:53, 24 October 2006 (UTC)

Sounds like my aunt, who is the only person I know who has this effect on anything electronic, mostly computers. Once we tested the phenomenon, she tried to dial-up with a modem and her daughter tried the same thing, and every time her daughter tried it worked. Weird. I would love to have an explanation for this. Her 'problem' is not as consistent or powerful as your wife's though; finally my aunt has found a laptop that seems to be behaving itself for the last few years. Could be due to a specific EM frequency that interferes with certain devices, as we are all beings of energy emitting a frequency ourselves. I wonder if it is linked to intelligence, as she is the cleverest person I know. BTW I've read somewhere that our EM should be in sync with the solar EM, or it leads to health problems - could anyone verify this? Sandman30s 12:10, 24 October 2006 (UTC)

Perhaps it's a static electricity thing. Maybe your wife wears insulating shoes/slippers and drags here feet when she walks, building up a static charge that's hard on sensitive electronic components. You might want to buy "ruggedized" computers and watches, which may have some degree of EM shielding, so aren't quite as sensitive to that type of thing. StuRat 16:27, 24 October 2006 (UTC)

Hey, don't steal my answers. :) DirkvdM 07:32, 25 October 2006 (UTC)

Try this experiment: give your computer a very long monitor cord, long keyboard cord, and long mouse cord. Then let your wife use the computer while ten or twenty feet away from the computer case itself. If her body is somehow affecting the computer hardware, this may stop the failure. --Wjbeaty 02:00, 25 October 2006 (UTC)

About watch-killing: these reports are fairly common, see From the way most people describe the effect, "watch killing" is totally outside of conventional science. Human bodies don't have a significant electrical field that could have an effect on a watch battery. So, if it really does happen, the explanation would contain a scientific revolution (sort of like discovering a genuine version of "subspace fields" from Star Trek.) --Wjbeaty 02:00, 25 October 2006 (UTC)

Could be just odds: Someone in the world *has* to win the zillion dollar lottery, and someone in the world has to break everything they touch. --Zeizmic 16:52, 24 October 2006 (UTC)

Perhaps she's a Stepford Wife and it's a result of the EMI that she produces?

Atlant 17:18, 24 October 2006 (UTC)

There is this Wal-mart that I go to that always charges me and whenever I reach for anything, I get shocked. I don't know why it happens and why it doesn't happen to people I go with either. So it's probably some sort of body chemestry, the way you walk, the clothing you wear, something to that nature. Of course, I don't break electronics often, as I'm usually the one who gets asked to fix computers and it works when I use it and they're like, "what did you do?" and I'm like, "Nothing." Also, when my ex-suitemate and I walked around anywhere, lights would go out very very often. Anywhere from garages to malls to you name it. I'm not saying it's supernatural powers, but I think there's something that amplifies or react to what's already there, which might be something as simple as more iron in the blood or how conductive you are etc. Maybe if you're not very conductive, you build up a charge and that affects things. I have no idea how it happens scientifically, or it's just very whacky coincidence. --Wirbelwindヴィルヴェルヴィント (talk) 17:45, 24 October 2006 (UTC)

My grandfathr had to carry a pocket watch, because every wristwatch failed. I think it may have because he worked hard outdoors and had particularly corrosive or salty sweat. Computers have sometimes failed, at lease in decades past, because of static electricity from users (generally female) who wear nylons, or wool, and are insulated by plastic shoes. A sizeable static charge can build up. Data processing rooms had controlled humidity to reduce static buildup. I can't believe anyone has a sufficient electrical field around their body (other than static discharge) to magnetize a watch. In my experience, I had to get within a foot of a conductor carrying several hundred amps to affect a watch.Edison 22:04, 24 October 2006 (UTC)

application

can provide me the uses of molecular markers in relation to fruits and vegetables?

• It would help if you gave a little more information about what you're trying to do. Have you googled for molecular markers or read our article about them? - Mgm| 07:55, 24 October 2006 (UTC)

Touch lamps

How do those touch lamps that you can touch and they light on work? Body capacitance claims it is the body's natural EM field, but that sounds hardly right. X (SUPERDESK|Help me improve) 07:54, 24 October 2006 (UTC)

how about this Xcomradex 08:17, 24 October 2006 (UTC)

A friend of mine built one based on capacitance for his computron. —Bromskloss 08:50, 24 October 2006 (UTC)

This question came up here before. The body of the lamp is charged and discharged repeatedly. The time it takes to charge and discharge is easy to measure and stays pretty much the same. When you touch it, your body changes the time it takes for the lamp to charge/discharge, allowing the lamp to know it is being touched. --Kainaw 15:21, 24 October 2006 (UTC)

How much energy does it waste with this constant charging/discharging?

One can charge and discharge an ideal capacitor (a capacitor with no leakage or series resistance) endlessly while wasting no power. But practically speaking, the complete controller probably wastes less than a watt; the gizmos are small and can be built entirely into lamp sockets, so they certainly can't be dissipating much power or they'd get hot.

Atlant 17:24, 24 October 2006 (UTC)

science

give information about nutriton

Welcome to Misplaced Pages. You can easily look up this topic yourself. Please see nutrition. For future questions, try using the search box at the top left of the screen. It's much quicker, and you will probably find a clearer answer. If you still don't understand, add a further question below by clicking the "edit" button to the right of your question title. --Shantavira 08:57, 24 October 2006 (UTC)

Great answer, hi-five! X (SUPERDESK|Help me improve) 18:41, 24 October 2006 (UTC)

Can I steal it? --Zeizmic 22:03, 24 October 2006 (UTC)

• Sigh* okay. X (SUPERDESK|Help me improve) 22:17, 24 October 2006 (UTC)

Receive information about nutrition from Shantavira's response. :)! --Proficient 23:56, 29 October 2006 (UTC)

Sitting up while asleep

I have never sleepwalked, but ever since I was a child I have often found myself sitting upright in my sleep, sometimes several times in a night. Sometimes I simply open my eyes to find myself sitting up, and other times I seem to be vaguely aware of sitting up as though "half-asleep". I'm not sure if it prevents me from getting the rest I need, but it might be bad for my back since I don't have good posture when I'm asleep...I'm not really worried enough to consult an expert though. I just want to know if anyone has heard of this before. I guess I am also curious about the causes of weird sleep behaviour - why me, what causes me to do this? --Grace 11:38, 24 October 2006 (UTC)

This sounds as though it is a harmless precursor to sleepwalking. Check out the last external link on that page. It would also be worth mentioning to your doctor.--Shantavira 12:26, 24 October 2006 (UTC)

I do stuff like that, although not as often as you. I never got it checked out though, I never cared that much. I will say, though, that I am far more likely to exhibit those types of behaviours when I'm very busy/stressed. Anchoress 12:41, 24 October 2006 (UTC)

Premature rigor mortis ? :-) StuRat 16:02, 24 October 2006 (UTC)

See parasomnia for more information. X (SUPERDESK|Help me improve) 17:56, 24 October 2006 (UTC)

audio timescaling

Can you tell me if pitch synchronous granular synthesis is equivalent to pitch synchronous overlap and add (psola) method? THNX! --Ulisse0 14:59, 24 October 2006 (UTC)

"Please don't double post" is at the top of the page. Your question was answered on the computing desk. X (SUPERDESK|Help me improve) 22:16, 24 October 2006 (UTC)

I'm sorry.. You're right but I didn't know whether was the fittest desk .. --Ulisse0 17:25, 25 October 2006 (UTC)

Unexpected Item In The Bagging Area

When my mum and I went to pick up a few groceries recently at our local ASDA supercentre, we decided to use the automatic checkout system where you scan your own items. We had to get the assistant to scan her ID card and pin at least four times! What is wrong with these machines? If we were going to steal something, we wouldn't put it in the bagging area, and these machines are so flaky that even if we did, the ASDA lady would just swipe her card and we'd get away with it anyway. At one point the machine told us to remove the unexpected item and as soon as we did, it told us that we'd removed an item and to put it back! --Username132 (talk) 17:08, 24 October 2006 (UTC)

The computer "knows" how much each item should weigh (based on its SKU number). After an object is scanned, the computer expects the total weight in the bagging area to increase by that much. But very light objects can fool it, especially if the scale, err, "bagging area" is already burdened by heavy objects.

Atlant 17:28, 24 October 2006 (UTC)

Yes, there's just no way the same scale can handle a 50 lb bag of dog food and yet still know when a greeting card is placed on it, and still have a reasonable price tag. They just need to trust their customers better. Perhaps they could have a "preferred customer card" (for those who have never tried to rip the store off) and only allow them to use the automatic check-out. StuRat 19:06, 24 October 2006 (UTC)

These automatic checkout machines still need work, that's true. Maybe RFID will provide the solution, where you'll be able to just put all your purchases into a shopping cart, walk through a scanner, and all the items in your cart will be recognised by the system. — QuantumEleven 11:44, 25 October 2006 (UTC)

Despite the problems, I prefer self-checkout, for many reasons:

• I can verify each price and complain when I'm overcharged.

• I can pack things as I want them, so the freezer items go together, for example.

• I'm not going to accidentally scan an item twice and not notice it, as a cashier might.

• I'm not going to confuse my groceries with the previous customers or next customers, as cashiers have done, even when using the little plastic divider (although those are frequently missing, too).

• I'm not going to put a greeting card down in the leaked milk from the previous customer, as a cashier would.

• Since one cashier now watches over 4 lanes, instead of one, there's the potential for this practice to reduce lines. I say "potential", however, because they are just as likely to fire 7/8 of their cashiers and have the lines be twice as long.

StuRat 21:55, 25 October 2006 (UTC)

Chemistry

Write the usual group configuration notation for each d-block group. How do the group numbers of those groups relate to the number of outer s and d electrons?

Aha! I think someone is trying to get away with not doing their homework themselves! :-) If you ask about the principle, rather than request the solution of your particular problem, you are much more likely to get an answer. As can be seen somewhere among the vast amounts of text in the beginning of this page, people here won't do your homework, but can perhaps help you learn how to do it yourself. (Also, it's a good thing to sign your comments with "~~~~".) —Bromskloss 16:14, 24 October 2006 (UTC)

This isn't homework. dudewhoaskedthequestion 11:43, 24 October 2006 (UTC)

Sure as hell sounds exactly like it. See electron orbital and the table to the right. X (SUPERDESK|Help me improve) 17:55, 24 October 2006 (UTC)

you owned me

Low testosterone and high hemoglobin/iron test

I have been on testosterone for 6 months because it was very low (way lower than norm). My dr. suggested I take a topical cream version which worked great. My problem is my iron was to high and getting higher each time I took a test. I gave blood as often as they would allow. My hemoglobin stayed high and got steadily higher which put me in a higher risk of heart attack or stroke. So the dr. as of this moment, is taking me off testosterone cream and wants to send me to another dr. that deals with this kind of thing. Can anyone explain in easy lay terms what is going on? How can a 46 yr. old man have second to the lowest testosterone level a dr. has ever seen and a high iron/hemoglobin count in the blood? I am 30 lbs. overweight and 6'5" tall. I am not sedentary, but work in an office long hours and travel a lot.

Any information would be great, but please only reply to this question if you know by experience or knowledge.

thank you, richard

If your elevated hemoglobin was only after you'd been using the testosterone, it's pretty much expected: testosterone will often cause an increased hemoglobin. So it may simply be an issue of working out an appropriate dosage. This is something that your doctor should be able to clarify. Presumably you are being sent to an endocrinologist for evaluation of your low testosterone. - Nunh-huh 22:41, 24 October 2006 (UTC)

I assume your doctor will send you to an endocrinologist, who can answer your questions and will not tell you that you have the "second lowest testosterone" he has ever seen. Your height suggests gonadotropins and maybe karyotype should be checked unless your parents were extremely tall; there may be other issues to be addressed. Good luck. alteripse 22:52, 24 October 2006 (UTC)

first sex

on 17 april 2007 i m going to married and till today i did not seen any nude girl so i am very much worried how i do a safe sex and how i find that she had the hymen tell me detail about the sexual intercourse

Although I doubt this is a serious question, read the articles on safe sex, hymen, and sexual intercourse. Click on any links you are not familiar with. Be warned though, there's some scary stuff out there. :yikes!: If you want to see a nude girl than go to nude. Or type it in google. X (SUPERDESK|Help me improve) 17:52, 24 October 2006 (UTC)

Enough internet access to ask a question on Misplaced Pages, but never seen a naked woman? That's like half the content of the internets... -- Scientizzle 19:36, 24 October 2006 (UTC)

You don't even need to search on the internet. You can see naked women on wikipedia right here. 211.28.178.86 12:49, 25 October 2006 (UTC)

Whats ur age?

Maybe he means nude girls in reality, i.e. not merely an image of one. --WikiSlasher 11:31, 27 October 2006 (UTC)

Where Art Though Contact Lens

If I rub my eye, sometimes my contact lens dissapears off somewhere under my eyelid and after much trauma comes back out, often folded. Where does it go and what happens to it on its journey? --Username132 (talk) 17:00, 24 October 2006 (UTC)

Mine also like to go for a "morning swim", somwhere under the eyelids, when I first put them in. StuRat 18:56, 24 October 2006 (UTC)

Don't rub your eye! But seriously, some people have perfectly spherical eyes, which leaves nothing for the lens to catch on to. Most people have slightly conical eyes and the curvature of the lens is happiest there. --Zeizmic 21:01, 24 October 2006 (UTC)

You might consider trying rigid gas permeable lenses. They're a bitch to get used to but they're far better behaved in my experience. EdC 21:23, 24 October 2006 (UTC)

vacuolated glandular endometrial cells

i have apparently got vacuolated glandular endometrial cells in my pap smear results - does anyone understand the pathology of these? Are they inevitably cancerous, or precancerous, or just a bit odd? I have to wait at least a month for a colposcopy, hence the need to ask here.

Thanks,

Scared 81.153.246.135 17:58, 24 October 2006 (UTC)

The article on Pap smear does not give much information about false positive results. I found an article that talks about "vacuolated to dense variable cytoplasm" in endocervical glandular epithelium during pregnancy and in the postpartum period. "In 9/11 cases, subsequent cervical smears on multiple occasions were negative." In this study, the pap smear false-positive rate was 44.8%. Results from one pap smear are fairly meaningless; there needs to be follow-up testing. --JWSchmidt 03:45, 25 October 2006 (UTC)

Thanks JWSchmidt - I hadn't found that article on pubmed - interesting. Looks like these cells can appear during/after pregnancy and then disappear so are probably hormone-related. In my case they've appeared without pregnancy so if anyone has any others leads please let me know. Searching for vacuolated glandular cells has taught me more than I want to know about sheep, flounders, algae and regularly-cycling women but I'm still in the dark as regards non-regularly cycling women!

Scared

Defibrillators and stupid people...

Anyone got any tragi-comic stories about idiots misusing defibrillators for kicks and giggles and the results thereof? There was a story in the news a couple of years ago about a doctor who decided (as a show of bravado) to place the paddles against his own temples and administer a jolt. I think he died, or at least spent a very long time in a coma. --Kurt Shaped Box 21:47, 24 October 2006 (UTC)

You might find it interesting to read about the War of the currents where Thomas Edison (no relation) had his people electricute animals from dogs up through an elephant to show AC electricity, especially at high voltage, was more lethal than DC. One of his assistants placed the dog on the energized metal plates and got the jolt, but lived to tell about it. Defibs were researched and promoted by electric companies to save workers who got electricuted, before they became a hospital fixture. Many electrical workers have been jolted by various AC and DC sources and lived to tell about it. Many did not survive. It's hard to picture anyone thinking it would be fun to get or give a high voltage, high current shock. Edison 22:15, 24 October 2006 (UTC)

Never underestimate the power of human stupidity, especially when alcohol or the words "I was only having a laugh" are involved. Defibrillators bring people back to life, remember? You see it in TV medical dramas all the time. I wonder how many of the people that know this also know that defibrillators can kill if used improperly? This story isn't funny at all, as an innocent person ended up dead but it does show that these incidents do occur - . --Kurt Shaped Box 22:35, 24 October 2006 (UTC)

Even worse are the words, "watch this..." alteripse 22:53, 24 October 2006 (UTC)

"Don't worry - it's not loaded..."? "God says..."? --Kurt Shaped Box 22:58, 24 October 2006 (UTC)

How dangerous is it actually to undergo defibrillation? We may suppose that the patient is healthy (and thus of course not really in need of it) so as not to confuse causes of death or so. You really can die, you say? —Bromskloss 22:28, 24 October 2006 (UTC)

Very recently, here in Austin, Texas, a portable defib was applied to a high school football player who'd collapsed, and indeed saved his life. However, the Doctor's misuse of the defib calls to mind actors such as Jon-Erik Hexim, who put prop pistols loaded with blanks to their temples for "kicks and giggles" -- yet were not so fortunate as to score a leisurely coma.Wolfgangus 23:00, 24 October 2006 (UTC)

How's about the guys who find pieces of unexploded ordnance from whatever war was their last war and start messing around with them, assuming that they're duds? There was a story on the Darwin Awards site (can't seem to find it now) about a Vietnamese guy who found an old landmine and started stomping on it to impress his buddies in the bar, with predictable results. --Kurt Shaped Box 23:33, 24 October 2006 (UTC)

Where to buy sulphur

Are there any websites the sell pure elemental sulphur in small quantities (100-1000g)?

• Sure! , for example, $7.40 for 500g. Just do a Google search for "chemical sales' -- there are lots of sources. --jpgordon 22:22, 24 October 2006 (UTC)

You can also buy it at many agricultural stores. I don't know what farmers use it for, but it is usually there. --liquidGhoul 23:34, 24 October 2006 (UTC)

Brimstones "Я" Us ? :-) StuRat 03:33, 25 October 2006 (UTC)

Brimstones ya us? DirkvdM 07:41, 25 October 2006 (UTC)

See Toys "R" Us. --Tardis 15:19, 25 October 2006 (UTC)

October 25

Function of small intestine

I met a fellow last night who has had all his small intestine removed. He says he feels ok and can eat anything he wants. What is therefore the function of the small intestine?--Light current 00:18, 25 October 2006 (UTC)

Did you ask him what his bowel movements are like? As I understand it, he'll have diarrhoea every time he uses the toilet because his gut is now not long enough to absorb the majority of the moisture/grease from the food he eats. --Kurt Shaped Box 00:21, 25 October 2006 (UTC)

He didnt mention bowel movements but implied all as normal and he felt really fit!--Light current 00:24, 25 October 2006 (UTC)

Could just be one of those wierd strokes of luck, then (either that, or your buddy is trying to make light of things). There was once someone who got shot in the side of the head, lost almost 50% of his brain and still made a full recovery. Anyone know if that guy has a WP article? I saw a documentary on TV not so long back about him - I think he was Indian. --Kurt Shaped Box 00:32, 25 October 2006 (UTC)

Maybe he only had part of his small intestine removed. I didnt like to probe him too deeply in public 8-)--Light current 00:36, 25 October 2006 (UTC)

I believe the small intestine primarily removes nutrients from the food and passes them on to the body, while the large intestine primarily removes water. So, if his entire small intestine was removed he would have trouble getting his nutrients. If only a portion was removed, then his ability to absorb nutrients would only be reduced by that portion. Eating more food (and making sure it was nutritious) could compensate, in such a case. StuRat 03:30, 25 October 2006 (UTC)

Yes thinking about it, he cant have all of it removed or he'd be dead. What you say makes sense. 8-)--Light current 04:35, 25 October 2006 (UTC)

I believe there are people who've had almost their entire digestive system removed (due to cancer, for instance). They can still survive by getting their nutrition via an IV drip. Not pleasant, but preferable to death, for most people. StuRat 05:45, 25 October 2006 (UTC)

The small intestine has three parts, with different purposes. The duodenum receives digestive enzymes and chemicals from the gallbladder and pancrease, which mainly break down macronutrients, especially lipids, into manageable chunks, this section also neutralizes stomach acid. The jejunum pretty much is just a tube in which chemical digestion occurs and nutrients are absorbed. The ileum fulfills the same rolls, and also selectively absorbs vitamin B-12 and bile salts, and makes sure that the colon does not get overrun by bacteria by small intestreleasing lymphocytes. Water is absorbed mostly in the large intestine, so removal of the small intestine would not necessarily cause chronic diarrhea, though it probably often does. However, even with all of that, most of the jejunum and ileum can be removed without too much of a change in diet, because absortion of most nutrients can happen just about anywhere in the system. Tuckerekcut 21:43, 25 October 2006 (UTC)

Thats good to know!

--Light current 21:50, 25 October 2006 (UTC)

On a semi-related topic, there are people who have had their stomachs removed (I know of a group of cousins with a genetic tendency to stomach cancer) who seem to survive, needing only to eat less and more often. —Daniel (‽) 22:11, 25 October 2006 (UTC)

Latent heat

What is the explanation of latent heat of fusion or evaporation. Where does this energy actually go?--Light current 00:23, 25 October 2006 (UTC)

It takes energy to break the inter-molecular bonds.

Atlant 00:37, 25 October 2006 (UTC)

So its potential energy given to the substance?--Light current 00:39, 25 October 2006 (UTC)

I would say it's thermal energy converted into a higher energy state for the molecules. This heat energy would be returned during condensation. StuRat 03:15, 25 October 2006 (UTC)

Yeah but its not ordinary heat energy because the temperature doesnt rise whilst the latent energy is going in. So how is this extra energy stored? Is it bonding energy as Atlant says?--Light current 03:21, 25 October 2006 (UTC)

Seems like StuRat confused you a bit. The energy it takes to break molecular bonds is thermal energy, that is, heat. But there is indeed no change in temperature. This is why you distingish between "heat" and "latent heat" - the latter does not change the temperature, but it's still a form of heat. This is why temperature alone isn't enough to quantify the internal energy of the substance. --BluePlatypus 11:55, 25 October 2006 (UTC)

evaporation? in particular: "... as the faster-moving molecules escape, the remaining molecules have lower average kinetic energy, and the temperature of the liquid thus decreases. This phenomenon is also called evaporative cooling. ". Xcomradex 10:43, 25 October 2006 (UTC)

Same process, slightly different circumstances. The temperature of the liquid changes in that case because some of the energy required to break the bonds and evaporate is being drawn from liquid. But the temperature of the liquid and evaporated gas combined remains the same. --BluePlatypus 11:55, 25 October 2006 (UTC)

That's not quite true — the temperature of the combined system really can go down (especially if the escaping molecules "just manage it", so they're not moving very quickly). Of course, assigning a temperature to evaporating water is itself dodgy, since that system is not in thermodynamic equilibrium. The point is that water under no water vapor has an excess of energy (from the unnaturally complete degree to which the molecules are associated) relative to systems in equilibrium that seem to have the same temperature. So when some of the water evaporates, we discover that its "real" temperature is lower, corresponding to the state without the excess energy. --Tardis 15:15, 25 October 2006 (UTC)

Global population of gorillas?

Approximately what is the global population of gorillas? The article doesn't say. 68.37.115.8 00:28, 25 October 2006 (UTC)

The 2004 estimate was about 5000. --liquidGhoul 01:11, 25 October 2006 (UTC)

Note that of the most famous variety, the Mountain Gorilla, there are only 380 left. DirkvdM 07:48, 25 October 2006 (UTC)

I didn't realize there were so few gorillas. --00:02, 30 October 2006 (UTC)

Volume of semen during ejaculations

I've measured the volume of my ejaculations and they usually vary between 4cc and 6cc. Isn't the average volume of an ejaculation supposed to be 10ccs? Does this mean that I'm less fertile than other men? I'm getting a bit worried about this but I'd feel stupid going to the doctors about it. --84.69.92.172 00:59, 25 October 2006 (UTC)

Do you have a measuring cylinder?--Light current 01:03, 25 October 2006 (UTC)

Yes. I know that sounds weird but I started checking it out after a woman said that my ejacualtions were weak. --84.69.92.172 01:05, 25 October 2006 (UTC)

Short answer: Most likely, no. Less semen is not an indication that you are less fertile. Maybe someone else would like to give the long answer.--Russoc4 01:05, 25 October 2006 (UTC)

Someone said here a few weeks a go that the more protein you eat the greater the volume is! 8-)--Light current 01:08, 25 October 2006 (UTC)

Almost right. I said that, since excess protein is used to create sperm, your sperm production will go up if you eat more protein. However, since the majority of seminal fluid is not sperm, but rather water, a reduction in the amount of sperm won't necessarily have a noticeable effect on the total volume. However, low sperm production does lead to a lowered sex drive, which could result in fewer ejaculations. In this case, each individual ejaculation could actually be larger in volume. StuRat 03:11, 25 October 2006 (UTC)

Someone said something about eating loads of asparagus too. No idea if it works or not - I can't stand the stuff, in spite of its alleged benefits. --Kurt Shaped Box 01:10, 25 October 2006 (UTC)

Ah-ha! Snopes' article on the band 10CC says the average is only about 3 cc anyway. Confusing Manifestation 02:36, 25 October 2006 (UTC)

1. Each ejaculate contains 3-10 million sperm cells or so. I don't know the exact figures, to be honest, but I think it's around that range. I highly doubt 3 million sperm cells are going to make you infertile.

2. The only thing I have heard about asparagus is that it makes semen taste and smell horrible to people who can detect the enzyme (if you eat asparagus and can smell an awful smell in your urine afterwards, you can).

3. I don't think it's extra protein, else if someone has no extra protein, they won't produce any ejaculate, which I don't think is true.

Yes, during periods of starvation, both male and female reproductive systems shut down, as part of the starvation response. StuRat 17:11, 25 October 2006 (UTC)

4. And as for the strength, there are excercises to strengthen it. I read a long time ago about a hot and cold home remedy for weak ejaculations. Something about alternating hot and cold somewhere by your genitals. But I have never tried, and I don't know if it's a myth or not.

5. Also, frequent ejaculations can make it weaker, I believe.

--Wirbelwindヴィルヴェルヴィント (talk) 05:50, 25 October 2006 (UTC)

I'd just like to point out that there really isn't much "extra" protein in the body. The pool of free amino acids in the body is only about 100mg in total. This amount is very strictly regulated by the urea cycle. Excess protein is very quickly degraded into aminos and turned into urea. There are plenty of proteins in semen, both intra- and extracellular, but semen is in no way an "overflow conduit" for excess protein, thats what urine is for. Also, sperm makes up a very small percentage of the volume of semen, most of the liquid comes from the seminal vesicles and prostate and BU glands, so volume is not a good indicator for number of sperm. Stimulating a cremaster reflex at the moment of ejaculation with a cold compress to the scrotum can help push all of the fluid out at the same time (by putting pressure on the perineum, there is little to no mobile fluid in the vas deferens themselves), but will not increase the overall volume. Finally, 6mL is typical for an adult, at least that's the "goal" volume for at least one sperm bank in my area. Tuckerekcut 21:31, 25 October 2006 (UTC)

It sounds like you misinterpretted my comments. I did not say that any excess protein is automatically changed into sperm, but rather I said that a certain amount of excess protein (beyond what is needed for life-critical functions) is needed for sperm production. Thus, an extremely low protein diet will lead to a substantial reduction in sperm count. StuRat 21:41, 25 October 2006 (UTC)

Fermenting blood to create an alcoholic beverage?

I'm sure that most people here have heard the urban legend that Jaegermeister is made from fermented deer's blood. I'm curious - would it actually be possible to ferment animal blood to make booze? --Kurt Shaped Box 01:37, 25 October 2006 (UTC)

Is there fermentation without sugar (or starch to turn into sugar)? Unless you are insulin-dependent diabetic, I don't think you'll have enough sugar in your blood to get any good results. Maybe the legend is based on diabetic deer. --Kainaw 01:41, 25 October 2006 (UTC)

Of course you could add sugar to the blood and ferment that. DirkvdM 07:56, 25 October 2006 (UTC)

Nope, never heard that legend. Seems a bit weird given how many people drink herbal-flavored distilled liquor. (E.g. Hungarian Unicum or Scandinavian Aquavit) Well anyway, it's possible to ferment into alcohol anything that has sugar in it. But blood doesn't have much sugar in it (even if you're diabetic). Grape juice, a popular object of fermentation, has over 100 times the sugar (by weight) that blood has. You'd be better of milking the deer and fermenting that. The Mongolians actually do that out of horse milk, see Kumis. --BluePlatypus 11:41, 25 October 2006 (UTC)

Though blood may have a small % of sugar. With a diferential mearsuring from 4% - 7%. It is possible to compound those sugar parts into a small volume. Having boiled blood to stabelize the environment for fermentaion I realized that all the blood tissue turns solid so addition water is needed. The water that remained when the clotted tissue is strained away contained sugar. It should be possible to rinse many gallons through one gallon of water. Or reduce the original batch by boiling off excess water (having myself condensed and carmalized the sugar to an imesurable state excess of 25%+). This extraction process has not been fermented long scale yet. The results will need studding. 11/13/08

Fermentation notes: Fermentation is slow or nothing. With a sugar level of 14% in 1/2quart volume. I added a small amount of Dried Malt Extract (DME). This addition was to support the yeast's nutritional needs. Later observation has shown a slow decrease in sugar. It may have been benificial to run a malt enzime to break down any sugar complexes in the blood sugar if they are in a complex form. Odor is pleasent. No visual defects. Sugar reading 12.5% 1/13/09

No, it was deer shit ;-) Sorry, this urban legend sounds just too brainless--Baruch ben Alexander - ☠☢☣ 04:52, 31 January 2010 (UTC)

Endangered large cats

What large cats are endangered? --68.37.115.8 01:47, 25 October 2006 (UTC)

There's a complete list (not just cats) at List of endangered animal species. I think the answer is roughly "all of them". -- Rick Block (talk) 02:20, 25 October 2006 (UTC)

thanks

Of the species mentioned in our article Big cat, the following are found on this list of endangered animal species:

• Tiger (Panthera tigris)
• Snow Leopard (Uncia uncia)
• Iberian Lynx (Lynx pardinus)

 --Lambiam 15:35, 25 October 2006 (UTC)

There are many more, e.g. the whole genus Parantica. Since they carry the common name "Tiger", I'm wondering if the information in Big cat is accurate. — Sebastian (talk) 20:37, 25 October 2006 (UTC)

Cotton

How does Damp Cotton Absorb Sulfuryl Chloride gas used in radical chlorination (what chemical reactions occur)?

So you've got cotton, "dampness", and sulfuryl chloride. What are the chemical formulas/structures of those things? What are some characteristic reactions of them (nucleophile, electrophile, acid, base, oxidant, reductant, radical initiator, radical quencher)? Can you think of a way any pair could react? DMacks 04:31, 25 October 2006 (UTC)

Also note that adding water to cotton will greatly increase the reaction surface area over plain water and a gas. StuRat 05:40, 25 October 2006 (UTC)

Electrolytes

How can you tell what is a strong or weak Electrolyte when you are given a chemical formula / compound(s)? Is there certain elements that define this? certain rules? (maybe like solubility rules ) And are most (strong) bases weak electrolytes and most (strong) acids are strong electrolytes? etc. In addition, the Strong electrolyte"For strong electrolytes, a single reaction arrow shows that the reaction occurs completely in one direction, in contrast to the dissociation of weak electrolytes, which both ionize and re-bond in significant quantities" how would you know when it would be both ionizes and re-bonds (or doesn't) if you just had the compounds' names? (sorry if i'm a little incoherrent)--Agester 04:20, 25 October 2006 (UTC)

The electrolytic strength of a compound is the degree to which it dissociates into ions in solution, which is always an equillibrium. So the strength/weakness is relative. Whether a strong acid/base is also a strong electrolyte depends on how it works. E.g. nitric acid dissociates very much into nitrate and hydrogen ions and is therefore a strong electrolyte. But ammonia, a strong base, will form ammonium ions from the hydrogen ions in solution, which has no effect on the solution's ionic strength. So it can correspond to both the solubility and the pKa, but not necessarily. --BluePlatypus 11:26, 25 October 2006 (UTC)

I understand what you said. However, how would you be able to know which is stronger or weaker electrolyte? For example H₂SO₄ is a strong electrolyte but H₂SO₃ maybe a weak electrolyte. What defines their difference with respect to electrolyte properties? --Agester 23:56, 25 October 2006 (UTC)

The best way is to look at the bond holding the H atom to the rest of the acid. If the remainder - what will eventually form the or - contains some highly electronegative elements, the chances are that the bond to the H atom will be severely polarised and weakened, leading to a larger Ka value. Look at the Ka values of chloroethanoic acid, dichloroethanoic acid and trichloroethanoic acid to see what I mean.--G N Frykman 07:38, 26 October 2006 (UTC)

hmm... i see. I appreciate your help and everything and i understand it. However, I haven't learnt about pKa in my class yet so it's still a little unclear for me (I did read the pKa article and it would help me greatly if we were taught this when we were discussing what is a strong and weak electrolyte). Once again thanks for helping! However, i guess the only way for me to know is memorize what is a strong and weak electrolyte! 8( --Agester 00:51, 27 October 2006 (UTC)

Sense of Color In Animals

Is it true that some animals sense only black and white images not color images? Thanks!

Yes. its true. 202.168.50.40 05:17, 25 October 2006 (UTC)

Although grayscale might be a more accurate description than black and white. StuRat 05:35, 25 October 2006 (UTC)

Still more accurate might be 'light intensity'. DirkvdM 07:59, 25 October 2006 (UTC)

Also consider, for example, lepidoptera - butterflies - who ID flowers in the ultraviolet spectrum; the patterns and colors in the UV wavelength are drastically different than how we see them.Wolfgangus 05:54, 25 October 2006 (UTC)

This is known as chromacy. Humans are trichromats, because we see 3 "primary colors" (three sections of the "visible" spectrum) and mix them together to create our rainbow. As wolfgangus reports, some butterflies are tetra- or pentachromats, with four or five primary colors to work with. I have heard that there is some kind of shrimp that sees the world in eight primary colors, thus "octochromacy". Monochromacy is a more technical name for what you called "black and white" vision (with the additional explanations above). According to our article monochromat, sea mammals are monochromats, but not many other animals are. Dogs, as with most other land mammals, are dichromats, which have vision comparable to a color blind person. They can see colors, but not as many as the average human. See dichromat for further explanation. Tuckerekcut 13:05, 25 October 2006 (UTC)

The shrimp that you are thinking of is the mantis shrimp, which has the most advanced color vision in the animal kingdom. – ClockworkSoul 13:33, 25 October 2006 (UTC)

Let's not forget tetrachromats. --Kjoonlee 16:32, 26 October 2006 (UTC)

Thanks to Tuckererkcut - a far more comprehensive explanation, which taught me a number of things as well.Wolfgangus 13:46, 25 October 2006 (UTC)

400Hz Frequency Apllied to Copper Conductors.

Hi,

Can anyone tell me how the use of 400Hz frequency affects the cable characteristics used on a 230V 63Amp supply. I believe that the increase in frequency increases the inductive reactance, decreases the capacitive reactance by up to a factor of 8. This then in turn affects the resistance of the cable by increasing it by a factor of 8. If this is the case how would one go about estimating the approximate cable sizes required for such an installation.

Thank you very much.

As part of your project, see Skin effect. Then grab a good electromagnetics textbook and a computer modelling and graphics program which can solve for the current distribution as a function of frequency and current. Have fun. Edison 17:25, 25 October 2006 (UTC)

I believe 400Hz is a common supply frequency for aircraft--Light current 15:22, 26 October 2006 (UTC)

Cable sizes are usually worked out on current. You dont need to worry about frequency IMO.--Light current 15:23, 26 October 2006 (UTC)

As the frequency increases, more of the current flows along the outer portion. Once again, read Skin effect.Edison 22:52, 29 October 2006 (UTC)

"scientific" name for grass. . .

. . .no, not canabus but the grass in your lawn. That name is needed for my son's class and he has not been able to find it anywhere. I know there are many kinds of grass but he was to find the scientific name for "grass" in general. Please help. . . I tried to find it here but had no idea how to start correctly. I did try a little but came up with nothing. Thank you so much, Mary McVey (I am using a friend's computer)

• Take a look at the lawn article. You will find what you need there. :) – ClockworkSoul 17:22, 25 October 2006 (UTC)

• As a hint, try clicking on the links in the first proper sentence in that article. Skittle 22:48, 25 October 2006 (UTC)

Amazing stuff, grass (even if we exclude the cannabis variety). Not only very useful to humans, for our lawns, food, construction, musical instruments and paper. But also, it's extremely simple and successful (the most successfull plant family even?). Yet it has only evolved very recently; for 99.8% of the evolution time span there was no grass. I wonder if there was something similar that grass replaced. Surely if something so simple can be so successfull, evolution would have come up with something similar sooner, right? DirkvdM 13:57, 26 October 2006 (UTC)

Grasses (or grass like plants) have been around for quite a long time, dinousaurs ate them. Also, evolution doesn't 'know' that something is going to be successful. And generally, whether or not something is a 'success' depends a lot on other factors. We have been amazingly successful 'til now (at least compared to many of the larger mammals) but it took evolution a long time to come up with us... Nil Einne 14:24, 26 October 2006 (UTC)

Yeah, but we're complex. Grass is simple, and I suppose that is part of its strength. DirkvdM 09:34, 27 October 2006 (UTC)

Insulation R-values

I have noticed a difference in R-values between similar products in Australia and Canada. 90 mm fibreglass insulation in Canada has a fairly standard rating of R-12 but a 90 mm product in Australia only goes up to R-2. Is there a different standard applied or is the manufacturing process that different? Any feedback would be appreciated. Thanks 209.89.148.249 19:17, 25 October 2006 (UTC)

Insulation materials are often characterised by their R value. In countries like Australia, which use metric measures, the units of R are m²K/W. An R=2 insulation material passes 0.5 watts per square metre with a 1 degree temperature difference. In countries using imperial measure, R is based on imperial units and a 50mm rockwool batt would have an R of around 40. --Zeizmic 22:57, 25 October 2006 (UTC)

Temperature - Kinetic Energy Relationship

I can't find a cogent equation anywhere to relate the energy difference between two states with temps T1 and T2. Any help? Thanks

First, find out the specific heat capacity of the material. Then multiply it by the difference between T1 and T2. Multiply this result by the mass of the material. --Bowlhover 20:45, 25 October 2006 (UTC)

Thanks! I'd forgotten that

Self-dissolving Miracle-Gro

What is the opposite of evaporation? Well OK, that's too easy - it is just condensation, but that _may_ not be what I'm looking for. I've got a packet of Miracle-Gro which is a popular plant fertilizer. You can buy it in a number of forms, but in this case it a box containing a plastic bag of blue crystals (looking rather like copper sulphate crystals, but I guess its more than that). You dissolve a spoonful in water before watering your houseplants every couple of weeks. Now, after opening the bag and leaving it around for about a year or so (my plants have a poor, impoverished and generally undernourished life - hey they are lucky to get watered), the blue crystals appear to absorb moisture from the atmosphere, to the point where they self-dissolve to form an aqueous solution in the folds of the plastic bag.

This strikes me as slightly unusual. Plenty of solids absorb water from the atmosphere, but AFIK few do so to such an extent that they become a liquid. So what is this process called? -- Solipsist 21:33, 25 October 2006 (UTC)

Sounds like they are deliquescent. DMacks 22:05, 25 October 2006 (UTC)

Yeah. They Stu stew in their own juice! 8-)--Light current 22:56, 25 October 2006 (UTC)

Taste and aging

Are you born with the all the taste buds you'll ever have or do they continually regenerate, like hair? What causes the loss of taste as you grow older? Clarityfiend 22:15, 25 October 2006 (UTC)

Possibly because elder people tend to take more medications, which may in turn produce that side effect. I'm not completly sure though. Hello32020 22:41, 25 October 2006 (UTC)

It is not the tastebuds that die along the way to getting old, it is the olfactory receptor neurons that do. One's sense of smell, along with mouthfeel, texture, and gustatory system sensations are the main contributers to taste. X (SUPERDESK|Help me improve) 07:16, 26 October 2006 (UTC)

And yes, they regenerate. Dismas| 19:09, 26 October 2006 (UTC)

green leaves all over the ground

In my area (eastern Iowa, USA), fresh green leaves, rather than yellow, red, and brown, are littering the ground. There are still plenty of green leaves on the trees as well as some colored ones. I've never seen this happen before. We've had fairly normal winds. The fall season has been abnormal, with very warm alternating with downright cold. What gives?

Also, what causes the leaves to separate from the tree in the first place? I read somewhere it's not because the leaves dry up, but rather that the leaves dry up because of some process in the tree that more or less casts them off. Is there anything to that? --Halcatalyst 22:23, 25 October 2006 (UTC)

Try the Color change in leaves article. It says, among other things, "In late summer, the veins that carry fluids into and out of the leaf are gradually closed off as a layer of special cork cells forms at the base of each leaf. As this cork layer develops, water and mineral intake into the leaf is reduced, slowly at first, and then more rapidly. It is during this time that the chlorophyll begins to decrease." I'm sure we should have something else on the process somewhere. Skittle 22:45, 25 October 2006 (UTC)

The process is called senescence, but our article isn't that great with it. You are right, the plant does not just dry up. A lot of energy goes into creating the cells of a leaf, so they take as much of that back as possible. The reason the leaves change colour is that the chlorophyll is one of the things the plant takes back for energy. This removes the green colour. Since the most abundant colour is gone, the next most abundant becomes visible. The plant obviously doesn't want to lose its leaves beofre it takes out all the nutrients, so the process of abscission is next, and only occurs once the plant is finished with the leaf. Abscission also occurs with fruit, but in the opposite direction. The plant pumps in the nutrients, and once that is done, it will remove the fruit. --liquidGhoul 01:23, 26 October 2006 (UTC)

That, however, does not yet answer the question. Why do the trees not take the chlorophyl out of the leaves? Are there two disitinct processes for that and the abscission? Might senescence be controlled by temperature and abscission by time? That would explain it. DirkvdM 14:12, 26 October 2006 (UTC)

I couldn't tell you why this has suddenly occured for those trees. My bet would be that there was some kind of stress which caused the trees to shed their leaves. I doubt it is global warming, but it could easily be some sort of pollution. The triggering of abscission comes from the end of senescence. A healthy, green, leaf is constantly creating a hormone called auxin. As the leaf goes through senescence, the auxin levels decrease, which begins a series of steps which eventually leads to abscission. I think the beginning of senescence comes from day length, but it is probably very complicated (as all things living are), so there will be other factors. --liquidGhoul 15:03, 26 October 2006 (UTC)

I probably should know be able to explain the basics but but I've kind of forgotten most of it. However this article appears to cover the basics and the links are helpful. However it doesn't really answer your main question. But as you may have gotten from you reading, senescence and abscission (as with most plant processes) are rather complex processes involving multiple hormones and multiple signalling pathways and it's not actually something we have a complete understanding of yet. Nil Einne 14:42, 26 October 2006 (UTC)

Btw, here in Amsterdam, most trees are still largely green, which is very abnormal for this time of year. However, the leaves that have fallen aren't green, so we seem to have more intelligent trees. :) Don't know what kind of trees they are, though, which will of course be the most important thing here. DirkvdM 14:12, 26 October 2006 (UTC)

reverse casimer effect??

I read somewhere that someone claimed that the casimer effect couldbe changed to be repulsive rather than attractive how can that be if the plates push together because of the zero point energy pushing on the outside of the plates, you cannot add to the zero point energy so how can this work. This is based on the NASA webbsite that describes the casimer effect much like air pressure, less between the plates so more pushing on the outside so they push together, how can you reverse this? FRed

Funny, I thought it was called the Casimir effect!--Light current 22:53, 25 October 2006 (UTC)

The plates would have to be close to massless, and extremely far apart for the effect to be "reversed," and is fairly implausible. X (SUPERDESK|Help me improve) 07:13, 26 October 2006 (UTC)

The idea of a reverse Casimir effect was discussed in the context of speculations whether very advanced technology worm holes might allow for time travel. Apart from giving fodder to SF authors this is of interest in research on general relativity: Due to the grandfather paradox causality would break down if it turned out that the laws of physics allow for time travel and if only under most exotic circumstances. In reasoning for the chronology protection conjecture it was said that a worm hole cannot be stable enough to send something into the past, and the counter-argument was given by Kip Thorne et al. that negative Casimir pressure might be used to keep it open. As I forgot the details I googled for Thorne and Casimir. You might find these links interesting: This science column from Analog Science Fiction and Fact that explains Thorne et al.'s work for the laymen and these notes on the homepage of Thorne's collaborator Matt Visser. Simon A. 13:03, 29 October 2006 (UTC)

October 26

When They Test You For Genital Herpes, Do They Take A Blood Test?

Like, how do they do it? Danke.100110100 01:04, 26 October 2006 (UTC)

IIRC, generally it's a blood test. Samples of an open sore can be tested, but that (obviously) requires that one already have a suspicious open sore on your genitals. DMacks 05:08, 26 October 2006 (UTC)

I'm not sure but I think this user might have a rather poor understanding of the human circulation system and may think you need to take blood from the genital region. You don't, the blood will usually come from the arm as always Nil Einne 13:58, 26 October 2006 (UTC)

A blood test for HSV2 (genital herpes) does exist, and tests for the antibody (the thing you producde to fight it). Alternative methods include swabs of the genitals, and pcr amplification of the material found. The latter I have seen only in academic studies. --TeaDrinker 19:27, 26 October 2006 (UTC)

There are several ways to test for genital herpes infection. One method of testing is a viral culture from a smear or swab of a vesicle (blister). That test is not perfect; it will be positive in about 70% of active lesions. Direct fluorescent antibody testing of a smear of vesicle fluid is about 90% sensitive. Polymerase Chain Reaction (PCR) testing is very sensitive but is also very expensive and therefore not typicaly used for routine clinical diagnosis. Blood tests are useful in two situations in regards to genital herpes infection. First, in a person who is experiencing what appears to be their first herpes outbreak, blood tests obtained when the rash breaks out and about 2 weeks later will demonstrate an increase in antibodies to Herpes Simplex Virus (HSV), thus strongly supporting the assumption that the herpes virus casued the original outbreak. The second situation in which blood tests can be useful is to rule herpes out as the cause of a chronic recurring genital rash. If a serum antibody test is negative for herpes, that strongly suggests that herpes is not the cause.

Microscope Lenses

My teacher gave a very bizarre and un-scientific sounding explanation for how lenses work within optical microscopes. They were talking about reflective lenses, giving a diagram of a curved lens reflecting directly away from it, resulting in a larger image on the same plane as the original. After what I already know, and reading Microscope and Lenses, I can see that they use refractive lenses on common optical microscopes. My question is this: Is it possible to magnify things reflectively, and is it used anywhere? One example that I can think of is Reflector telescope (which seems like the reverse of the described process), but would actual microscopes use such things? The Uglymancer 01:23, 26 October 2006 (UTC)

As far as I know, no microscope uses reflection to increase magnification, but I could be wrong. I do know that binoculars use reflection in part of the optical path in order to have a long light path contained within a short physical housing. See the article on porro prism and the article on binoculars for more. 192.168.1.1 6:50, 24 Rocktober 2006 (PST)

Is it possible to magnify things reflectively, and is it used anywhere? -- youbetcha, see Dallas67 04:39, 26 October 2006 (UTC)

The optics used in the steppers used to "print" the patterns on integrated circuits are mostly reflective (because the wavelengths used keep getting shorter and shorter, and there aren't good transmissive materials for these wavelengths). Steppers actually use reducing optics rather than magnifying optics, but they still prove the point. The really interesting stuff is coming up though; we're crossing the boundary into what used to be called "soft X-rays" but now are called (less scarely) "extreme ultraviolet"; these will need "grazing reflective optics" where the light is reflected at very shallow angles. I think you can find more about X-ray mirrors if you follow some links from our Chandra X-ray Observatory article or here.

Atlant 23:23, 27 October 2006 (UTC)

Help with relativity

I am trying to help my daughter with all of her homework and we are never going to be finished with all of it, so I need alittle help. One of her questions that we both can't figure out is,"You have learned about the Newton's concepts of motion, force and energy, and Einstein's theories of special and general relativity add a new twist as how the working s of nature are perceived. Comment on a feature of one of the theories that interests you. Use your imagination and come up with an idea how it might have real life application or even used in a science fiction story."Please help she really needs this grade. Every time you all have always hit the nail on the head with the questions. THANKS!!!!!!!!—Preceding unsigned comment added by 205.188.116.74 (talk • contribs)

You want us to tell your daughter what interests her and use her imagination? I'm not sure we can help with this part. Look at the articles on astronomy, generaly relativity, special relativity and newtonian physics. There are plenty of applications from astronomy to medicine. --Tbeatty 02:50, 26 October 2006 (UTC)

Since this question requires imagination, we can't exactly help without practically completing it for you. Try the articles on Classical mechanics, Special relativity and General relativity if you need some reading material. -- Consumed Crustacean (talk) 02:53, 26 October 2006 (UTC)

Because we're all a bunch of guys that don't have any imagination.X (SUPERDESK|Help me improve) 07:10, 26 October 2006 (UTC)

Nah, we have active (some would say over-active) imaginations. But even when we're pondering physics, I doubt we're imagining the same things as someone who's had the same level of science and worldly experience and been in the same science class as your daughter. DMacks 08:49, 26 October 2006 (UTC)

Or her teacher. Pffst, stupid assignment. —Bromskloss 10:01, 26 October 2006 (UTC)

I wouldn't say it's a stupid question. It's perhaps not really a physics question but it is IMHO a good question. It requires one to actually think and understand the concepts rather then just parroting something which is good since too many students can only parrot. No one said your answer has to be the same as the teachers or anyone else's. Provided you demonstrate an actual understanding of the concepts and an ability to think, I would assume you would be given your marks. This isn't a right or wrong answer question... BTW we do have imaginations. I'm thinking how old is your daugther? Over the age of consent I hope? I'm imagining what she looks like...... Er you probably don't want to hear the rest. (Okay I made this up but I'm sure there are some wikipedians thinking it). Nil Einne 13:49, 26 October 2006 (UTC)

BTW I got this from the reference desk a while back "it would be really kewl if your parents went on a trip to a nearby blackhole for 2 weeks then you will be 20 years older than your parents when they return --RedStaR 20:55, 27 September 2006 (UTC)". While it's talking about black holes, in actual fact if your parents were travelling at or close to the speed of the light they could easily end up younger then you as time would be travelling much slower for them (see Time dilation). This obviously has implications for SF... Nil Einne 13:48, 26 October 2006 (UTC)

How would helping high school children with homework, help them when they have to write their exam all on their own? It's the same with study groups - you don't write exams in groups. Also, if the answer requires imagination, the only way to develop imagination is 'try it yourself' and not ask for help. As Einstein added the fourth dimension into Newton's classical laws of physics, perhaps your daughter should do some research on time travel or time paradoxes - right into the realm of science fiction where imagination has no boundary. Sandman30s 12:02, 26 October 2006 (UTC)

Hmm, time travel, black holes as portals thru time and space, parallel dimensions...I'm sure something interesting is out there. StuRat 00:11, 27 October 2006 (UTC)

chemical reactions

how could i know what chemical products can be produced in a reaction simply by knowing the reactants (and apart from memorizing them)? for example, for the thermal decomposition of hydrated copper (ii) sulphate crystals...is sulphuric acid formed and copper oxide and hydrogen gas? how can i tell, simply by looking at it?

One important thing to do is to write down a reaction for whatever you propose and see if it can be balanced. If you can't make it balance, it's probably not something that happens:) After that, it comes down to proposing lots of likely things. That means knowing the general kinds of reactions that happen, not memorizing a lot of specifics. For example, you perhaps know that many acids are compounds that can release H+ in solution, and you can probably even recognize many such compounds by their name or formula without explicitly memorizing every acidic compound explicitly. For the situation here, here's a hint: many hydrates can undergo a common reaction by virtue of their being hydrates. DMacks 08:41, 26 October 2006 (UTC)

Well, apart from some simple and relatively well-known cases, as in classic inorganic chemistry, you can't actually tell exactly how stuff is going to react. That's what chemists know and what they're needed for. But the knowledge itself doesn't follow any simple rule. It's a mix of stuff learned by heart (and generalizing it) simple but approximate rules and intuition, more or less. It's basically a large part of what chemistry is all about, so I can't really suggest more than just "learn chemistry". --BluePlatypus 14:08, 26 October 2006 (UTC)

In the example you mention, a small amount of chemical experience will suggest that the water in the crystals is not very strongly held there, whereas the other ionic bonds in the copper sulphate are much stronger. So heating hydrated copper(II) sulphate (at a moderate temperature, anyway) will cause there to be a thermal decomposition reaction, merely producing steam and a white solid known as anhydrous copper sulphate. If hydrogen was going to be given off, it would require there to be a redox reaction, and simply heating a solid isn't likely to do this. I'm afraid that experience with experiments will enable you to predict the outcome of unfamiliar reactions much more easily. --G N Frykman 22:04, 26 October 2006 (UTC)

Geography

I have some topics on which i am not getting any information. i have searched a lot but not getting what i need, so i need ur help for this.

And your specific question would be .... ??? JackofOz 10:53, 26 October 2006 (UTC)

i have some topics on which i am not getting any information. they havee asked to choose any one realms of the earth.i have taken earth. then they have asked to find

• the diversity of enviroment that exists in the world which supports life.
• ollect stories,legends,festivals,poetry,sayings,rituals,associated to water
• write a report on how mans interaction with nature has resulted in different hazardous situation such as:- deforestation and soil erosion causing floods and droughts water scarcity in rural and urban areas.

if u would just tell me from where i can get this information and the sites i would really be gratefull to you. thx.

This is a very large research project. Looks like dozens of hours of work, and 20-40 pages. I would take time to invest in research techniques, such as using Google, or libraries. Good luck! --Zeizmic 11:44, 26 October 2006 (UTC)

Or Misplaced Pages of course: biodiversity, water, deforestation, soil erosion, flood and drought might be good starting points (haven't looked at them myself - that's your job). DirkvdM 14:27, 26 October 2006 (UTC)

Derivation and Use of Clausius-Clapeyron relation

Hi everyone. From the article Clausius-Clapeyron relation, I'm confusing about its derivation. It says that

Along the coexistence curve, we also have dμI = dμII.  

And after that we use the ${\displaystyle d\mu =-sdT+vdP}$ relation to give the final formula. My question is that we use two points in the coexistence (phase-equilibrium) curve to derive the formula. Those two points describe the same situations where there are two phase appeared in equilibrium in the system. Hence, the Clausius-Clapeyron equation should be used only for describing a change between two points along the phase-equilibrium curve.

But commonly we use it to refer about latent heat for describing phase transition. We try to describe two situations between a point at equilibrium (two phase) and a point outside the equilibrium curve (only one phase). So why is the equation valid in this case? I know I'm missing some important concept here. Thanks everyone for your attention. -- 131.111.164.228 11:13, 26 October 2006 (UTC)

It's derived at equillibrium between the two phases and describes the relation between the latent heat of the phase change and the associated changes in temperature, pressure and volume. The latent heat of the phase change is what it's all about. If you want to study the change between states that aren't in equillibrium, then you set up a thermodynamic cycle. --BluePlatypus 14:00, 26 October 2006 (UTC)

As far as I know, the Clausius-Clapeyron equation gives an approximation to the slope of the coexistence curve--that's it. ("Equillibrium" is a tricky word because thermodynamic equillibrium is a separate concept from phase equillibrium.) It says nothing about states of single phase, nor does it even describe the coexistence curve properly--firstly, it's a linear equation (which most coexistence curves are not); secondly, it only describes the transition between two out of three possible phases. In other words, I am questioning the validity of your last paragraph. Ckerr

It is not an approximation at all. It is exact. Nor is it a linear equation. It's a PDE. Now, if you chose to integrate that as if it wasn't, which some people certainly do, then it becomes an approximation. But it's not one present in the equation itself. --BluePlatypus 21:00, 26 October 2006 (UTC)

The points I and II are actually the same point on a PT diagram; they are different points on a VT, or PS, or VS diagrams. You do not take two different points on a melting curve on a PT diagram, you just take one point (which gives you the temperature at which your element would melt under given pressure, provided the pressure does not change in the process). Now you would like to know what is the melting curve slope at that point. Here the Clausius-Clapeyron equation becomes useful. You see, that single point in a PT diagram becomes an infinite number of points when you go to the VT diagram. Indeed, under given P and T, when you are on the melting curve, you can vary the fraction of phase I in the mixture continuously between 0 and 100%. This changes V (as the specific volumes of the two phases differ, generally speaking), without changing either P or T or mju (but changing S). The Clausius-Clapeyron equation is then derived from the fact that mju stays constant. The two points used in the derivation are at the same P and T; simply, one is 100% phase I, 0% phase II; and the second one is 0% phase I, 100% phase II. The slope is thus defined at a point (PT) proper, not at two close points. Hope this helps. Dr_Dima

Thank you all very much -- 131.111.164.110 09:24, 30 October 2006 (UTC)

Expert In Opacity Needed

Hey. The article Opacity (optics) is in need of a rewrite from an expert. I'm not one. However, if anyone has any assistance that they can render, it would be appreciated! Scalene 11:34, 26 October 2006 (UTC)

• You could always post a message on Misplaced Pages talk:WikiProject Physics. They may be able to help you. – ClockworkSoul 13:51, 26 October 2006 (UTC)

I rewrote it, although I'm not claiming it's complete (or that I'm an expert). Feel free to remove the help tags if I've done a good job with it. I also proposed a merge, if anyone's interested in helping with that. --Tardis 15:33, 26 October 2006 (UTC)

Added a paragraph. Some important things are still missing (self-absorption, relation to line profiles, absorption mechanisms, etc...). Which level are we aiming at: high school? undergraduates? experts in adjacent fields? --Dr_Dima

All levels. A Misplaced Pages article should start out with an intro that those with the least background can understand, then build up to the most complex theory, at the end. StuRat 23:50, 26 October 2006 (UTC)

Eiinstein's theories

I am trying to solve a problem but I am stumped, please help. How can you add a new twist as how the workings of nature are perceived when using Einstein's theories? and how might it have real life applications? Thanks!!!

—The preceding unsigned comment was added by 205.188.116.74 (talk) at 00:58, 27 October 2006.

Your question is vague - Albert Einstein worked on many theories throughout his life, which are you referring to? However, in any case, you should do your own homework (see the top of this page). — QuantumEleven 13:07, 26 October 2006 (UTC)

See the same question above. The user is simply repeating the question with less info thinking he or she can con us in to helping. However our answer is the same Nil Einne 13:41, 26 October 2006 (UTC)

A good try though ! If this is a different user trying to get the homework done from us, see Misplaced Pages:Reference_desk/Science#Help_with_relativity -- Wikicheng 13:46, 26 October 2006 (UTC

I am doing my own homework, and I am not pertending to be someone else in order to get you to help. All I was asking is to help out, but as usual you have one or two of you trying to be smart about a question. I will not ask another question from you and the donations that come from the Miller Foundation will also be ceased. Thanks anyway.

I sincerely hope that until you grow up you will not be allowed to handle any significant amount of money. Cryonic Mammoth 16:52, 26 October 2006 (UTC)

This question I actually feel negatively towards. It evokes some anger response in me. That's scary. Please try before you ask here. This is a very easy question, and we would answer it, but I know I wouldn't feel like I answered it much at all without at least a page. X (SUPERDESK|Help me improve) 04:28, 27 October 2006 (UTC)

If you don't mind my asking, to exactly which Miller Foundation are you referring, and over how much of their funding do you have direct control? There's the Miller Foundation, the Brittaney Miller Foundation, the Rush-Miller Foundation... Try to be more explicit in your vague, unsubstantiated threats. Black Carrot 21:06, 27 October 2006 (UTC)

research project

i have to find info on sampling and randomisation but i cannot find anything on representitive sample any search engine i use comes back with no information

Please sign your posts and don't add a space as the first character because it screws up text. I suggest you use a different search engine. Google finds quite a bit of stuff with representitive sample. Of course, it helps a LOT if you spell it right and search for representative sample instead but Google will usually make you aware when you spell a word wrong (and as I said you get useful stuff however you spell it). Alternatively use a spell checker. BTW, sampling on Google also give a lot of useful links as does randomisation and the alternative (predominantly US) spelling randomization. So really I don't know what search engines you tried but you should add google to your list. I also found useful wikipedia articles with these searches and using the wikipedia search would probably find the same article... Nil Einne 14:15, 26 October 2006 (UTC)

Randomisation? DirkvdM 14:30, 26 October 2006 (UTC)

Well actually Sampling (statistics) is probably what the above reader needs, but I was trying to encourage him/her to actually search Nil Einne 14:46, 26 October 2006 (UTC)

Focus and focal point

Quick question for the physics people: Is the focal point of a parabolic mirror located at the same point as the geometric focus of the parabola? Thanks, Zagalejo 14:18, 26 October 2006 (UTC)

Yes. Virogtheconq 14:39, 26 October 2006 (UTC)

It's not a proof, but it may help to remember that each point on a parabola is as far from the focus as from the directrix; it's therefore reasonable that the image of the focus in a parabolic mirror would be the directrix (many different images, in fact, from each point on the mirror). Since all the shortest-distance (perpendicular) lines from the directrix are parallel, light emitted from the focus is redirected into a parallel beam (the definition of the focal point). (It makes no real difference whether it's truly parabolic or is a circular paraboloid, except that in the former case the focus is a line, not a point.) --Tardis 15:06, 26 October 2006 (UTC)

Cool, thanks all. Zagalejo 23:41, 26 October 2006 (UTC)

Blind Dreams

What do people dream about if they have been blind all their lives? Is it purely sounds and textures? Paul venter 14:29, 26 October 2006 (UTC)

Good one. If the visual cortex is intact, I suppose they will have visual aspects to their dreams. But if it is never used (for lack of input), it might degenerate. Don't know, though. Of course, this would also depend on the cause of the blindness - I just assumed it was in the eyes, but if the visual cortex were deficient from birth they could never imagine colour, I suppose. DirkvdM 14:35, 26 October 2006 (UTC)

might be useful and both of which I found from (most alternatives also work). Short answer - usually yes if they're not congenitially blind, probably not if they are. Of course, although I haven't read the 2004 paper, I'm somewhat skeptical whether you could establish whether a congenitially blind person has visual dreams. Without any knowledge of what vision is like, how will they know if they are seeing something? Food for thought. Nil Einne 14:53, 26 October 2006 (UTC)

If they "knew" what shapes things were without touching them, that would be a way to know they were seeing them. There was an interesting sci-fi book where almost everyone was blind. One girl could see, so knew about things before she felt them, and everyone else thought she must be psychic. StuRat 23:43, 26 October 2006 (UTC)

One could check for activity in the visual cortex. That doesn't necessarily mean that they see the way we do, but of course the same goes for anyone else. I only assume that other people see things roughly the way I do (in a literal sense, I mean). That when I see the colour red, they will have a similar sensation. But of course I can never really know that. DirkvdM 09:38, 27 October 2006 (UTC)

You know, by a common definition of "psychic" (aka extrasensory perception), she would be. She has a sense they don't have, don't understand, and can't really even imagine. I've heard people claim that claivoyance is the "sixth sense", one with a corresponding sensory organ, which we just haven't tracked down yet. Of course, it'd be more than the sixth, even among the traditional senses, but the point is the same. Black Carrot 20:51, 27 October 2006 (UTC)

And, as a matter of fact, you can know that. Not yet, sure, but once we've actually got some clue how the brain works (cross your fingers), it should be fairly straightforward to demonstrate whether or not we process basic visual information the same. For instance, the retina has been thoroughly studied, and at least one stage (the photoreceptors themselves) has a fairly conclusive answer: there's quite a bit of similarity in the distributions of red, green, and blue photoreceptors from person to person, but some variation, which may or may not be accounted for by the brain itself. Black Carrot 20:55, 27 October 2006 (UTC)

One thing to keep in mind that not everybody who is defined as "blind" has absolutely no vision at all. Many do have some vision. --Robert Merkel 09:37, 28 October 2006 (UTC)

That's "legally blind", which is a rather silly legal term. They should be called "low vision" to distinguish between them and the truly blind. StuRat 16:09, 28 October 2006 (UTC)

See no evil ... ? DirkvdM 08:13, 29 October 2006 (UTC)

Vitrectomy aftermath

I assume the vitreous humor regrows after a Vitrectomy, but does anyone know how long it takes? My guess is the fluid would come back within a day or two, but the fibrous network may take some time after that - does it require leaving some of the humor behind as a seed, or will it all come back naturally? Virogtheconq 14:47, 26 October 2006 (UTC)

The vitreous does not regenerate spontaneously. To maintain the proper shape of the eye, chemically stable, optically clear, sterile viscous fluid is infused in its place. —Preceding unsigned comment added by Jodahy (talk • contribs)

The article also says that a gas is used and diffuses out gradually, meaning that eventually the humor returns. Obviously that won't happen spontaneously, but I'm interested in the timescale on which it happens. Virogtheconq 13:26, 27 October 2006 (UTC)

s and d orbitals

What does the s and d areas in the peroidic table have to do with orbital notation? 216.253.128.29 16:10, 26 October 2006 (UTC)nicholassayshi

• This picture might help you out a little bit.

The orbital names are s,p,d,f- in that order. On the periodic table, each atom is written with its electron configuration, showing which electron orbitals are filled.

For more info, look at the article on Electron configuration. It is explained there in more detail. Laurən 16:25, 26 October 2006 (UTC)

• A little more specific info, spdf designate the different shapes of the orbitals, also. Laurən 19:15, 26 October 2006 (UTC)

I also am trying to understand elctron configuration in orbitals. How does that image present electrons relatve to the nucleus? Are those the varied directions the electrons will appear from that orbital (with the nucleus being in the center). or is that a visual representation of one electron? More simply put, I am confused about the visual representaion of electron(s) and/or nucleus in those images of the orbitals. 69.150.209.15 19:22, 26 October 2006 (UTC)

Those are representations of the 3D region where an electron in a given orbital is likely to be found around a centrally-located nucleus. We can't actually locate a specific electron at a specific position, and electrons really are free to be located anywhere at all, even miles away. But we can talk about, over time, the where they "usually" are, a "probability density". So an electron in an s orbital is generally found in a spherically-symmetric region around a nucleus, whereas an electron in a p orbital is generally found in a dumbell-shaped region along a certain axis through the nucleus. DMacks 19:40, 26 October 2006 (UTC)

Basically, that happy little diagram where the electrons moved around the nucleus like planets around the sun was wrong. It's just a really simple way of showing it. And for the rest, DMacks pretty much has it covered. --AstoVidatu 21:55, 26 October 2006 (UTC)

I seem to remember from college chemistry that s,p,d and f stand for "secondary, primary, diffuse, and fine," perhaps from the appearance of spectral lines. So what is g?Edison 00:01, 27 October 2006 (UTC)

"g" is the letter after "f":) No, seriously...see Electron shell#Subshells. DMacks 01:42, 27 October 2006 (UTC)

Warm-bloodedness in birds and mammals.

Did warm-bloodedness evolve in a common ancestor of birds and mammals (was the most recent common ancestor of birds and mammals warm-blooded), or did it evolve independantly in the two groups? Would it be possible to determine this by comparing the mechanisms birds and mammals use to maintain thermal homeostasis? grendel|khan 17:07, 26 October 2006 (UTC)

Good question. There are many cases of convergent and parallel evolution, but our articles don't list this one. Cryonic Mammoth 17:14, 26 October 2006 (UTC)

Good question indeed. Looking up "endothermy evolution birds mammals" in google gives plenty of good hits. There seems to be quite a bit of argument going on about the details of warm-bloodedness evolution, but most seem to agree that the primary thermoregulation mechanisms are already present in reptiles. It's just the metabolism rate in reptiles that's not high enough. Dementios

Hmm... I'm not sure about birds and mammals, but homeothermy of a degree is found in fish (particualrly some kinds of Tuna and Lamniform sharks (see Salmon shark)). This is believed to have arisen independentally. --TeaDrinker 19:58, 26 October 2006 (UTC)

I think the current concensus is that they evolved it seperately (at least that is what we are being taught in uni). It is unknown, though seems to be actively argued, whether dinosaurs were warm blooded. However, I think mammals diverged from reptiles just after the amphibians, so there is a big gap there. --liquidGhoul 22:25, 26 October 2006 (UTC)

I was taught that they were not. That a lot of the similarities between birds and mammals (like the heart for example) are covergent evolution. Common ancester between birds and mammals go as far back as the reptiles, so i'd think not. With fish, it's defintely convergent evolution. Things like Tuna and sharks are slightly endothermic for completely different reasons. Where as things like whales are endothermic because they're not fish at all =). --`/aksha 01:50, 27 October 2006 (UTC)

Colour of semen

I have noticed my semen is a little less opaque and yellower than that of others. Does this mean something about sperm count, or tell anything else about my health? I have not yet tried to get my wife pregnant but we are considering that before the end of the year. I've never pointed that out and I strongly doubt she noticed it. Please let me know if this is a bad thing because I'll need to bring it up.

First, see a doctor for medical advice. Second, semen takes on a yellow tint as you age. It also turns yellow if you haven't had an orgasm in a long time. It also turns yellowish with a high sperm count. It also turns yellow in the presence of many common infections. So, yellow semen is just a symptom. You need to see a doctor to figure out what the cause of the symptom is. --Kainaw 19:02, 26 October 2006 (UTC)

Check your lighting, it easily appears yellow sometimes if it is in a "warm" color light. X (SUPERDESK|Help me improve) 04:51, 27 October 2006 (UTC)

I can't help but ask... what was your method of comparison? Rockpocket 06:42, 28 October 2006 (UTC)

Plane Crash

Which seats in a big airliner do you think are safer depending on the different types of crashes? It does happen quite often that a plane crashes and it is announced that "189 people died, and 3 survived" or sentences of that sort they never specify where the lucky ones were sitting. I was thinking more towards the tail of the plane, dont know why, it seems stronger somewhat but then that last Kentucky one only the co-pilote got dragged out of the burning plane by the fire brigade if I remember correctly. Any thoughts or statistics? Thank you. Keria 19:55, 26 October 2006 (UTC)

IIRC, you want to sit either near the tail, since that part usually absorbs the least amount of shock on impact, or you want to be around the wings, since that's the strongest part of the airframe. --BluePlatypus 20:53, 26 October 2006 (UTC)

Where is the fuel tank usually located? Might want to avoid sitting on top of that. --Kurt Shaped Box 23:02, 26 October 2006 (UTC)

I have heard, albeit not from a source that would know directly, that most deaths in plane crashes are from smoke inhalation and fire. Thus the best places to sit might be near the exits. Tuckerekcut 23:07, 26 October 2006 (UTC)

I have heard that the safest is by the wings, I believe from documentaries on National Geographic etc. It is both the strongest part of the plane as well as right by the exits. --Wirbelwindヴィルヴェルヴィント (talk) 23:30, 26 October 2006 (UTC)

Since you asked for statistics, I'd like to point out that since the odds of you dying in an airplane crash are lower than 1 in 5000 - over your entire lifetime, and your odds of dying on any given trip are roughly 1 in 6 million, your best bet in choosing a seat is to look at something like SeatGuru to choose the most comfortable seat -- particularly since your odds of being uncomfortable on any given flight approach 1 in 1. --ByeByeBaby 00:01, 27 October 2006 (UTC)

FYI the fuel tanks in most commercial airliners are in the wings. Larger aircraft such as the Boeing 747 also have tanks in the lower half of the fuselage. 192.168.1.1 5:21PM, 26 Rocktober 2006 (PST)

One look at controlled impact demonstration should change your mind about sitting above the wings. Xcomradex 01:41, 27 October 2006 (UTC)

Heh, it seems to be a total mess anyway, no matter where you sit. Hmm, all the passengers seem to be asleep, and the little one has apparently turned around, planting their face in the seat. :-) —Bromskloss 12:27, 27 October 2006 (UTC)

ByeByeBaby: These are odd statistics you are quoting there. Your two numbers only fit together if the average person does 6 mio / 5,000 = 1200 flight in his entire live. Do people really fly that much? Simon A. 13:17, 29 October 2006 (UTC)

No matter where you sit, the inside of the plane is likely to be a mess after any impact, since it's not designed to handle the same load conditions the structure is. I don't think it really matters where you'll be sitting since everything's going to get tossed around anyways - in that case, it'd probably be better to be seated close to the emergency exits, so avoid the previously-mentioned asphyxiation scenario. Virogtheconq 01:55, 27 October 2006 (UTC)

When we start falling I'll go lock myself in the toilets at the back. Thank you. Keria 08:55, 27 October 2006 (UTC)

There was a BBC documentary on this recently and the final conclusion someone drew was "We don't really know" because every plane crash is different. So those shots Xcomradex linked to are no indication at all. But two considerations were that near the wings the structure of the plane is extra reinforced and that it helps to sit near an exit. Especially that last bit seemed to be important. Also, bend forward before the plane crashes, so you won't slam into seat before you quite as hard, and try to immobilise your limbs so they won't go flapping about (your muscles can't possibly couteract the forces excerted on your body by a plane crash). Maybe wrap your arms aroun your legs. Oh, and if you land in water, inflate the life jacket at the moment you leave the plane, not before because it will hinder your movements in the melee of people scrambling over each other after the crash - the main reason to sit near an exit. DirkvdM 10:06, 27 October 2006 (UTC)

I don't have it handy, but a report I read from the FAA some time back said that sitting near an exit didn't guarantee you'd be able to use it. During even a mild crash, the fuselage telescopes slightly, resulting in compression forces which made it impossible to open the exits. One test showed that they had to tow the aircraft body forward for some distance to fully relieve the stresses and enable the exits to open. Additionally, in a severe crash, the fuselage will rupture in many places, creating new exits. 192.168.1.1 8:46, 27 Rocktober 2006 (PST)

On the other hand, given that there's a roughly equal probability of a "new exit" opening somewhere in the fuselage, then it's still somewhat safer to sit near the exits, since at least in the case you're not seated near one of the fissures there's still a chance of escape. Virogtheconq 01:36, 28 October 2006 (UTC)

The Science magazine?

Could anyone tell me how can I get the issues of the Science magazine, please? I live in Alexandria in northern Egypt.

--62.139.172.44 21:24, 26 October 2006 (UTC)

Go here for information on ordering an individual article/issue, and here to get information on subscribing. --AstoVidatu 21:59, 26 October 2006 (UTC)

Personal print subscriptions at $139 but digital subscriptions are only $99 and may be a much better deal oveseas to reduce shipping costs, delays, and losses. Most American and European universities and hospitals pay for free online access to Science at ] for all students and faculty. If you belong to a school or similar institution with a library, ask the librarian if they have access. Another possibility would be to search online for American library associations that send duplicate copies of scientific and medical journals overseas to poorer institutions, although you may not get complete sets and the issues may be months or a year old. alteripse 23:38, 26 October 2006 (UTC)

Well, if you go to a library, you might just as well read the paper issue there. :) That can be any major public library. And surely, Alexandria must have a good library. DirkvdM 10:11, 27 October 2006 (UTC)

Basic Physics: Force Question

A car and driver at m=3,000lb total moves at exactly v=60mph along a level, straight highway heading west to Vegas for five minutes. Is it true that during that time, the car has no west-bound force (f=m*a), because its acceleration is zero? Seems strange if that's true. --12.104.14.109 22:39, 26 October 2006 (UTC)

Yes it's true that the total force is zero. However there will still be forces acting on it. Friction will act eastwards so as to retard (slow down) the motion. Therefore the engine will have to provide a force to overcome this. These forces are equal and opposite, so the add up to zero. Theresa Knott | Taste the Korn 22:51, 26 October 2006 (UTC)

How can the total force be zero? The car is travelling westward at 60 mph. If the engine's power output exactly matches the force of friction, than the car won't go anywhere. The engine has to overcome friction, and move the car. (Maybe I'm missing something obvious here--if that's the case, please tell me!) --Bowlhover 04:11, 27 October 2006 (UTC)

Oh yes, once the car is moving, it only needs to overcome friction to maintain its speed. It only needs to accelerate at the very beginning of the journey. --Bowlhover 04:16, 27 October 2006 (UTC)

In physics terms, net force --> net acceleration through Newton's second law, F=m*a. If the car is moving at constant velocity, there is no acceleration. If there is no acceleration, there is no total (or net) force. --M1ss1ontomars2k4 04:24, 27 October 2006 (UTC)

You are missing Newton's first law of motion. If it is travelling at 60 mph, with no friction, it will continue to travel at 60 mph forever till another force acts upon it. Thus, to maintain speed, engines have to put enough force to cancel out friction (including the air). --Wirbelwindヴィルヴェルヴィント (talk) 05:24, 27 October 2006 (UTC)

You are probably getting confused with kinetic energy, which is very much dependend on the mass and velocity. --Wirbelwindヴィルヴェルヴィント (talk) 23:34, 26 October 2006 (UTC)

Could be a trick question involving the earth's rotation. A toilet in a 3,000 lb RV still flushes counterclockwise when it's moving at 60 mph. It is a Coriolis force that causes the rotation. --Tbeatty 03:04, 27 October 2006 (UTC)

Huh? What does this have to do with Earth's rotation? Also, toilets definitely do not flush counterclockwise because of the Coriolis effect. See http://www.snopes.com/science/coriolis.htm. Even dropping a feather into the toilet will affect the water's velocity thousands of times more strongly than Earth's rotation can. --Bowlhover 04:11, 27 October 2006 (UTC)

October 27

Where to Purchase Digestive Enzymes

I would appreciate if anyone would know where I could purchase these digestive enzymes:

Papain (Papaya), Bromelain (Pineapple), Ficin (Figs) and Actinidin (Kiwi). I am looking for a tablet or powdered form that is mostly the enzyme and tthe concentration for each enzyme is about the same, for comparison.

The problem I am finding is that the Health Stores only carry Papain and Bromelain and some of the biochemical companies sell only industrial size.

Would any universities carry them?

Thank you.

JDC

What country are you in? Are you at school? When i worked in a school lab we used to get most of our enzymes from normal school suppliers. SigmaAldrich carry pretty much everything but they will not sell to the public :-( Theresa Knott | Taste the Korn 00:14, 27 October 2006 (UTC)

The obvious question is: Why not eat the actual fruit to get all the good stuff, instead of hoping that whatever powder they give you actually contains what they claim ? StuRat 03:29, 27 October 2006 (UTC)

• Well, Bromelain is easy, as is papain, as you say. You can get ficin here (about a hundred bucks for 25g), among other places; not sure where you can get pure actinidin in small quantities, but there's a commercial preparation of it called Zylax being sold over the net. --jpgordon 17:22, 28 October 2006 (UTC)

Pectodictyon

What is this genus (of algae, apparently), and why aren't any descriptions of it available online? NeonMerlin 02:17, 27 October 2006 (UTC)

• Well, it's a genus within the family Hydrodictyaceae. – ClockworkSoul 04:46, 27 October 2006 (UTC)

Airships

I was reading the article on airships and finally made it to the artile discussing Orbital or high altitude airships. I was wondering if it is possible for a ballon or airship design to exist in a vacuum, wouldn't it explode? Also I read about JP areospace I think they have the right idea if it's possible but the ion drive is a bit farout. Is it possible with an airship in airless space to be driven with a rocket?67.126.141.80 04:44, 27 October 2006 (UTC)

An airship in a vacuum wouldn't explode (unless it was already close to exploding in air), but it wouldn't provide any lifting power. It would fall like a rock. How do you think a balloon works? Here's the relevant part from the first paragraph of the Airship article: ...primarily by means of a cavity (usually quite large) filled with a gas of lesser density than the surrounding atmosphere. If there is no surrounding atmosphere, it can't possibly work. —Keenan Pepper 05:02, 27 October 2006 (UTC)

A balloon can certainly exist in a vacuum: for example, the Echo satellites were balloons. It simply has to be constructed of a material that can withstand the temperatures it will encounter, which are likely to vary more in outer space than in the atmosphere. It's true that the same amount of gas inside will exert a stronger pressure on the balloon when it's in vacuum, and that could make it explode, but the simple solution to this is to use a smaller amount of gas inside.

Yes, you could drive a balloon in space by attaching it to a rocket, or to an ion drive. But it would not be functioning as an airship, because an airship floats in the air and in space it would not be floating on anything. On the other hand, if it was in orbit, it wouldn't need to.

--Anonymous, 05:05 UTC, October 27.

What? How could it possibly float if there is no air around it. No air is less dense than anything. --liquidGhoul 05:11, 27 October 2006 (UTC)

That's what I said, it would NOT be floating. --Anon, 22:43.

An airship in a vacuum would feel a greater amount of pressure on it than in an atmosphere, but good design will keep that under control. Bigelow Aerospace has successfully deployed some prototypes in orbit of inflatable modules (ultimately) designed for use in human-habitable stations, so it's quite doable. As to whether or not it would still qualify as an airship, that's a question of semantics, but it wouldn't get any sort of power from its internal gas - it would have to use a rocket or some traditional means of space propulsion to move. Virogtheconq 06:37, 27 October 2006 (UTC)

See Echo satellite for an article about early communication satellites which were giant balloons in space. Edison 12:27, 27 October 2006 (UTC)

composite materials

I need to do a Chemistry report and presentation. Hence, I need info about the meaning of composite materials, examples and components of composite materials, comparing and contrasting properties of composite materials, and justifying the properties of composite materials. If the information is received earlier, it would be better. Thank you. --61.6.47.6 06:24, 27 October 2006 (UTC)

Have you tried looking at composite material? It has everything you need right there. Virogtheconq 06:31, 27 October 2006 (UTC)

Sexual Dysfunction

Is there a cure for sexual dysfunction? How to solve premature ejaculation in males? What are the long term side effects of it? The male patient is 23 yrs old and has symptoms of the above? How long does one generally manintain his virginity? How does one define a virgin? Advise...

Although we are lucky enough to have several medical professionals who post to the boards, we discourage questions that require medical speculation or advice. After you read premature ejaculation, you might want to have 'the patient' contact a medical professional. Anchoress 09:08, 27 October 2006 (UTC)

How long can one maintain his sex drive? Till what age particularly the males?

See also Virgin, Sexual dysfunction, and Sex drive. Many people, male and female, retain a certain libido through old age, although typically diminished compared to when they were teenagers.  --Lambiam 10:51, 27 October 2006 (UTC)

There's a saying about male potency: 20 years old, triweekly. 50 years old, try weekly. 70 years old, try weakly. Edison 12:30, 27 October 2006 (UTC)

On loveline Dr. Drew sometimes talks about this premature ejaculation medicine that is in the works... something like an extremely short acting prozac. Xcfrommars 20:24, 27 October 2006 (UTC)

What is the age generally males have sex? Particularly in the west ?

Do you mean the first time they have sex? And what do you mean by "sex" - intercourse, masturbation, fellatio ... JackofOz 11:22, 30 October 2006 (UTC)

Communication Engineering

What is the difference between noise and distortion in communication?

Have you looked at our articles Noise and Distortion? In general, noise is a disturbance that is added to the signal, like hiss on an old grammophone record. Distortion can be any change in the signal shape, such as when a sound is muffled (high-frequency cut-off) or you turn up an amplifier too much.  --Lambiam 10:29, 27 October 2006 (UTC)

Simply put, distortion means a bad signal, while noise means no signal (or a random signal if you wish). Turn on the tv and take out the cable. The 'snow' you see is noise. DirkvdM 11:29, 27 October 2006 (UTC)

Ignore the above; it is noise. Actually "noise" can be used with two meanings: (1) additive disturbances, typically undesirable because they interfere with a proper transmission of the signal; (2) the same for a "zero" signal, so all that is left is "pure" noise.  --Lambiam 14:29, 27 October 2006 (UTC)

Electrical noise can be defined as an unwanted signal which is always present in a communication system. its presence tends to impede the reception of the wanted signal and is usually the limiting factor in its detection.

#

from Noise, F.R Connor, Pub. Edward Arnold 1973. ISBN 0 7131 3306 6. Chapter 1 para 1 --Light current 19:10, 27 October 2006 (UTC)

Noise is added to the signal from an external source, distortion is a modification of the signal through a non-linear function. --OpusPenguin 03:57, 28 October 2006 (UTC)

Yeah thats a nice defn, and one that I agree with apart from the fact that noise can be generated in the Rx. But do we have a valid source for that statement?--Light current 04:01, 28 October 2006 (UTC)

Hey, don't ignore me. Let me make some more noise. :)

Noise is 1) a random signal that 2) is unrelated to the intended signal. Or, as the noise article puts it, "an unwanted by-product of other activities". It also mentions the tv noise, but another good example is film grain. And I like the ad example, although that is not really random, just unrelated. I'm not as sure about the meaning of distortion, but I think noise is just one possible form of distortion. The distortion article, however, seems to contradict this. DirkvdM 09:38, 28 October 2006 (UTC)

Yes but an unwanted by product can also be distortion components. So the page is not accurate.--Light current 13:06, 28 October 2006 (UTC)

high frequency gravitational waves truth or myth

I have read about high frequency gravitational waves that should in theory have a number of effects such as propulsion and peterbation of objects, I have found a few webpages that deal with the subject that seem legitimate http://www.iop.org/EJ/abstract/0264-9381/22/10/046 http://www.iop.org/EJ/article/0264-9381/22/10/046/cqg5_10_046.pdf This one is from an institute used to study gravitational waves called LIGO http://www.ligo.caltech.edu/docs/G/G030067-00/G030067-00.ppt So are these waves a myth, a theory or can we just not make them yet? Rupert

Have you looked at Gravitational wave? In theory, whenever you wiggle your nose, it will generate gravitational radiation. However, despite strenuous efforts, scientists have not yet directly observed gravitational waves, not even from binary systems with black holes or neutron stars, much less from anything we can do.  --Lambiam 10:22, 27 October 2006 (UTC)

First of all, any gravitational wave would have the effects you mention, although the higher the frequency the more noticable the effect. As Lambian mentions the logistics of us creating them prevent us. It is almost certain that they do exist, but due to the weakenss of gravity they are very hard to detect. I can't remember how LIGO looked for them, but any terrestrial attempts are futile as the effect is almost certain to be lost amongst the vibrations of the planet. There is a mission planned that will use (I think) three satellites in orbit around the Sun with lasers pointing between them. If any gravitational waves move between them they should cause a blueshift in the lasers which could be detected. I hope I've been of some help.

All attempts at detection as far as I know are based on laser interferometry. The the satellite system, LISA looks promising. X (SUPERDESK|Help me improve) 04:31, 28 October 2006 (UTC)

Colour of dreams

A question that always evokes an interesting response, if not an intelligent answer, from people that I ask :) Do you dream in colour, or monochrome? Sandman30s 14:22, 27 October 2006 (UTC)

Colour. --liquidGhoul 14:27, 27 October 2006 (UTC)

Usually colours that are as vivid or more than in reality. Sometimes I have image-less dreams, or with dim and mute, almost monochromatic colours.  --Lambiam 14:34, 27 October 2006 (UTC)

Colour. Although I read somewhere that we all dream in colour, some people are just not capable of remembering in colour. :-)) Or they were trained to believe from a young age that some (or all) people dream in b/w, and that's what they've programmed themselves to remember. Anchoress 14:41, 27 October 2006 (UTC)

Generally I dream in colour, besides the odd exception. I've had a couple of grayscale dreams, or dreams which I remember being as such, but they were in the dark where I'd expect to see little if any colour in real life. I've also had a couple extremely abstract dreams that seemed to be purely black/white (ie. white letters on a black background, nothing else). There was also one which wasn't in grayscale but was all in shades of purple. -- Consumed Crustacean (talk) 15:37, 27 October 2006 (UTC)

Canadians dream in colour, Americans in color! This was the gist of my 1 min research on this issue: Recent experimental dream studies by Kahn et al. (11) have suggested that most, if not all, dreams are experienced in color, but that memory traces of the color perceptions are "bleached" progressively after awakening through various psychic mechanisms which are as yet unclear. --Zeizmic 15:44, 27 October 2006 (UTC)

And English people. This faq has always puzzled me. Why shouldn't people dream in colour if they see in colour? What would surely be remarkable is dreaming in shades of grey (or sepia, or anything else).--Shantavira 17:21, 27 October 2006 (UTC)

Places, people, situations and words are first remembered in dreams ; colors less, smells lesser (personal research). -- DLL 17:48, 27 October 2006 (UTC)

I remember seeing stuff, feeling buoyancy, the touch of the ground, and the wind, but I can't remember if what I saw was in colour or black-and-white. --Kjoonlee 18:41, 27 October 2006 (UTC)

Can't remember if what I heard was in stereo either. :( --Kjoonlee 18:42, 27 October 2006 (UTC)

Color. Black Carrot 20:35, 27 October 2006 (UTC)

Many people remember a time when most TV was watched in black and white, either because it was broadcast that way or because color TV sets were too expensive. Go back just a few more years and most movies were black and white as well. I suggest that if people ever did commonly dream in black and white, the reason is very likely that they were conditioned by these media to form images that way. Remember, dreams are largely based on real experiences, and those could include watching TV or movies. --Anonymous, 22:55 UTC, October 27.

I have never dreamed in black and white, although many times I lose one or more of the senses. X (SUPERDESK|Help me improve) 04:28, 28 October 2006 (UTC)

My mother said that the night after we had bought a colour tv, she dreamt in colour for the first time. Probably a better way to put that is to say that she dreamt about colour. Whether I dream in colour, I haven't a clue. I've never noticed or paid attention to it and considering that my normal vision is in colour, I would probably have noticed if any dream were not in colour, so I suppose they are. DirkvdM 09:47, 28 October 2006 (UTC)

Like I said, interesting :) Some people go almost into a daydream state, racking their mind for what their dreams look like. I like the dim and mute and sepia etc. descriptions. Usually means your dream is hazy because the conscious mind can't tap into the subconscious at will. When anything colourful becomes hazy, colours merge or blend into something not quite monochromatic but close. You should never dream in black and white btw unless you live in a b&w world. The media conditioning answer is convincing, but surely your dream will at some point include the tv's colourful surroundings? Sandman30s 11:48, 30 October 2006 (UTC)

Earthing/Grounding

What are the merits and demerits of using rod earthing or plate earthing in household electricity?Which one is better?amrahs 17:30, 27 October 2006 (UTC)

I'd imagine a plate would be significantly more expensive to install and may have initial settling issues but would have a much lower resistance to the general mass off earth due to its much larger contact area. Plugwash 17:41, 27 October 2006 (UTC)

If you're building a new house, I'd recommend you install a Ufer ground instead of a rod or plate ground. Ufer ground example. 192.168.1.1 11:50, 27 Rocktober 2006 (PST)

I believe this is only necessary if you are building something totally isolated from a town water system, like a farmhouse or a cottage. --Zeizmic 19:57, 27 October 2006 (UTC)

The main purposes of grounding are: lightning protection, and protection against downed high-voltage power lines. A good ground will provide a high-current path which keeps the occupants of the house from becoming part of the electric circuit. Ground is only used as part of energy transmission system if you're out in the wilderness and using a power line, and in that case the Utility company provides the grounding equipment. --Wjbeaty 02:20, 28 October 2006 (UTC)

""If requesting electrical wiring advice, please consider asking an electrical contractor or electrical engineer instead. That said, follow your local electrical code. Electricity is totally unforgiving of naivete or misunderstandings. Do not improvise methods based on "common sense." A short rod you stick in the ground by hand is about useless, as would be a small plate. In my part of the U.S. in normal soil conditions ground rods are generally used. Stainless steel rods are driven into rhe ground in about four foot sections. The first one has a sharp point. The following ones screw onto the first one. A driving cap is screwed onto the back while an electric or pneumatic driver drives it down. Sometimes 10 feet suffice, sometimes 30 feet is needed. The ground resistance is tested until it is down to the required level. Multiple rods a certain number of feet apart may be combined to lower the total resistance. Water pipes are not always sufficient, especially if there may be plastic anywhere in the system coming to the house. Allowable ground resistence depends on the available fault current and codes. If rock is hit, retry a few feet away or get a drilling rig. A plate system would have to be somehow deep enough to avoid damage from gardening etc and deep enough to stay moist, since ground resistance would increase in dry soil. The area where the plate system is would have to be marked or fenced off so no one ever damages it, as by trenching. It would somehow have to allow drainage. This plates might corrode away in a few years. The ground resistance of a deep rod is related to a hemispheric shell model. A plane would seem to lack the same area as a rod, at first blush, so you would have to excavate a large area. A commercial radio tower may have a series of radial cables buried to establish a ground . A substation in addition to a system of ground rods, may have a network of cables below the gravel to limit step and touch potentials in the event of a fault. In mountainous country, they have to improvise, such as grounds in springs or wells. Edison 16:28, 28 October 2006 (UTC)

measurement by vernier

how to use vernier caliper?

Go to vernier caliper and you can see one being used to measure a coin. --Kainaw 18:06, 27 October 2006 (UTC)

You probably mean Vernier scale. Vernier caliper redirects to caliper. BTW do you agree that it should rather redirect to Vernier scale? — Sebastian (talk) 22:09, 27 October 2006 (UTC)

I tried this instead of a redirect; what do you think? ike9898 03:55, 28 October 2006 (UTC)

If it is a vernier caliper, it is pretty easy. Just sandwich the movable tooth and fixed as close to the object as possilbe and read the ruler. I don't have one with me, and haven't used a caliper for a few months—reading it might be harder than that. X (SUPERDESK|Help me improve) 04:27, 28 October 2006 (UTC)

Tooth Transplant

Is it possible to get such a thing as a tooth transplant? Would I be able to get it done on the (UK) NHS as I am 17 and suffer from enamel hypoplasia.

Yours, Christopher

Assuming it was technically feasible (which I doubt), then, If you needed more than one tooth replacing, there would be a practical problem of getting a matching set to fit, unless they were all taken from a corpse with the same size mouth as yours. However, implants I believe are possible at about £2000 per tooth. 8-).--Light current 19:27, 27 October 2006 (UTC)

I'm no orthodontist, but wouldn't it be possible for the you to get a fake tooth implant instead of the real deal? If you haven't finished puberty you're probably close, so there would be no issue with the rest of the mouth outgrowing the fake tooth. (OK actually that last part makes little sense but my suggestion stands.) Hyenaste  19:58, 27 October 2006 (UTC)

About now as far as I know it is impossible to get real, living teeth transplanted. However, among other things, the future looks good for growing teeth. Turner's hypoplasia only affects one tooth, is this the case with you? Don't worry though, you can definitely get new teeth. My dad's teeth were pretty bad looking before he got some operations in Thailand. X (SUPERDESK|Help me improve) 04:24, 28 October 2006 (UTC)

Research is working on finding ways of transplanting or creating real teeth in place of missing ones, but at the moment implants are the closest things we have. - Dozenist talk 15:49, 28 October 2006 (UTC)

Walls

Do walls really need mortar? If so, why?--Light current 19:23, 27 October 2006 (UTC)

Walls don't need mortar, bricks do. But only if you want them to hold together. --BluePlatypus 19:25, 27 October 2006 (UTC)

OK do bricks/stones need mortar to make a wall and why?--Light current 19:28, 27 October 2006 (UTC)

So seagulls can't easily knock down the wall. --Zeizmic 19:50, 27 October 2006 (UTC)

Well if you have superglue, then you can use that to hold the bricks together. Otherwise, the bricks will just fall down every time there's a windstorm. --Bowlhover 19:59, 27 October 2006 (UTC)

Not true! Dry stone walls can last in wild windswept areas for centuries!--Light current 20:44, 27 October 2006 (UTC)

It all depends how massive the bricks/blocks/stones are. Plenty of walls, barns, and pyramids are built without mortar. Many single-skin walls built with mortar are actually quite easy to push over.--Shantavira 20:13, 27 October 2006 (UTC)

Mortar is just one of many ways to get blocks of stone or brick to stay together. Other methods include having overlapping pieces (like Legos) or just relying on mass and geometry to hold them together (as in Egyptian pyramids). Mortar seems to have a disadvantage that it doesn't last as long as the bricks or stones, so can shorten the life of a wall, relative to one held together by some other method. Mortar-free walls may also benefit from being able to expand and contract with changing temperatures, without building up stresses which result in cracks. Of course, anything connected to such walls also needs to be free to move, or the cracks will occur there. StuRat 20:38, 27 October 2006 (UTC)

Quite. It's certainly possible to do construction without mortar. Often such work demands much more skill from the craftsman, however. Each stone has to be carved to match the stone below. The aqueduct of Segovia is a Roman aqueduct built entirely without mortar that is nearly two thousand years old. TenOfAllTrades(talk) 20:49, 27 October 2006 (UTC)

So why do we actually use mortar in all modern masonry buildings?--Light current 20:53, 27 October 2006 (UTC)

Mass production concerns. It takes too long to assemble a wall from pieces that must be fit together like a puzzle - it's far cheaper and faster to manufacture bricks or quarry rocks and slap them together with some mortar.

Yeah but whats the mortar for???--Light current 21:48, 27 October 2006 (UTC)

It functions as an adhesive. AFAIK, the mortar penetrates the pores in bricks/rough surface on rocks before it cures, basically forming a bridge between otherwise separate pieces. 192.91.147.34 22:00, 27 October 2006 (UTC)

If it acts as an adhesive, what is its tensile strength? Concrete seems to have the lowest tenslie strength of any construction material ] --Light current 23:41, 27 October 2006 (UTC)

No, not just that. Economical concerns. You need a thicker wall, using more work and more material, to build a wall that doesn't need mortar. Also, it's almost impossible to make the wall wind-proof. Why would you spend more money on a worse wall? Just because something is possible doesn't make it economical or practical. Note, by the way, that just about nothing at all is built out of stone blocks today, even with mortar. When stone is used, it's just a facade to make things look nice. In the 19th century you'd have a stone or plaster facade with bricks beneath, but today even that is too exensive. Today it'd be a wall of girders and cinder-blocks or a concrete beneath. --BluePlatypus 21:45, 27 October 2006 (UTC)

It's ironic. In the middle ages they plastered bricks to make a smooth surface and today we hide the smooth surface of concrete with bricks. DirkvdM 10:07, 28 October 2006 (UTC)

Hence faster and cheaper. 192.91.147.34 22:00, 27 October 2006 (UTC)

Windproofing is easily provided by outside render or inside plaster. Why must stone walls fit together like a puzzle?--Light current 21:47, 27 October 2006 (UTC)

A really rough explanation would be that without good contact on all surfaces (fitting together like a puzzle), there's not enough static friction to maintain the stability of the wall. There are also practical engineering concerns relative to proper transmission of forces on the wall to the places most able to handle the stress. 192.91.147.34 22:02, 27 October 2006 (UTC)

I have seen it said that mortar isn't there so much to hold the bricks together as to hold them apart. That is, the important thing is that it adjusts its shape (before it dries) to the exact shape of each brick, so they fit together better than if they were just stacked, and then the weight of the bricks works to hold the wall together. Of course this is an exaggeration; the mortar does contribute some adhesive power as well. But not a lot -- which is why masonry construction is not recommended in earthquake zones. It doesn't have a lot of tensile strength, so the walls are subsceptible to being shaken apart. --Anonymous, 23:00 UTC, October 27.

I think Anonymous has provided the most satisfying (to me) answer yet. It makes perfect sense! Spreading the load seems very important. I wonder how many bricklayers know the answer?--Light current 23:52, 27 October 2006 (UTC)

For a house, you can't underestimate the importance of a weather shield from acid rain. The inside would accumulate water and cause mold (without a sealant, such as mortar). High-rises use a granite face, but each segment is sealed with silicone. You could put silicone as a mortar, but that's expensive, and only done for glass bricks. As well, in some circumstances, a well-mortared brick wall has considerable resistance to in-plane shear during an earthquake. --Zeizmic 01:46, 28 October 2006 (UTC)

Did I not already say that an external render could keep out the rain?--Light current 18:59, 28 October 2006 (UTC)

Wouldn't construction be a lot easier and faster if bricks had a standardised profile such that they would interlock, so you could just stack them? Sort of like Lego. Anyone can build a wall with that. No need to apply mortar or wait for it to dry. Possibly with a thin layer of plastic on the brick's surface to add friction and make a wall wind proof, although I doubt that would be necessary. Actually, doesn't something like that already exist? DirkvdM 10:07, 28 October 2006 (UTC)

That's a good question, and deserves it's own posting:

Why aren't large interlocking bricks practical for construction ?

(See discussion above.) StuRat 15:59, 28 October 2006 (UTC)

A Lego style brick wall, like the stone blocks fitted together by the Incas, is just the sort of thing used for retaining walls. The cast blocks interlock, and are used to cover an exposed dirt bank, like next to a sidewalk where the lawn is elevated a few feet. But they are not even close to waterproof. Water drains easily through the interfaces between the bricks. A tightly stacked brick wall would do the same, unless a rubber gasket, expanding foam or some such was installed between the bricks as a seal. The dimensional stability of such a gasketed wall would be questionable, since the gasket would compress over time. Cathedrals and castles were usually been built of large stone blocks without mortar. The stones have to be precisely shaped, or carved to match the irregularities of the one below as in Inca construction. The thickness of the stone blocks is great enougn to lessen the wind blowing through and moisture migration. Brick walls usually are far less thich, with a saving of materials. For stone blocks of jails, splines like cannonballs were sometimes placed in carved recesses in the stones between courses to make sure a stone could never be moved relative to its neighbors. Mortar acts as an adhesive to enhance the integrity of the wall and help prevent it being pushed over by external forces, but an old wall will often stay intact "by force of habit" even if the bricks are no longer stuck adhesively together.. The mortar is waterproof, or at least water resistant when new. A driven rain would come right through a stacked brick wall, so you could not have wood, plaster or drywall as an inside wall covering. If you had a stone or brick floor, the water would trickle down the wall and go away eventually. The mortar is softer than the brick, by design. The proportion of Portland cement in the mortar must not be too high, so that as the wall settles and moves tiny distances in settling, the mortar gives rather than the brick. After several decades, enough mortar will have washed away that Tuckpointing is needed, in which some crumbly mortar is chisled or ground away and fresh mortar troweled into the gap. A "struck joint" is done when the brick wall is first made, by using a pointing trowel to compress the mortar into the joint 1/4 inch or so. "Buttering the joint" is a poor tuckpointing practice of just filling in that gap with more mortar, which degrades the appearance of the wall.Edison 16:57, 28 October 2006 (UTC)

I don't know what sort of limit you've applied to "large," but I've built a couple retaining walls before using interlocking bricks (I don't recall the exact size, but it was somewhere around half a cubic foot) without mortar. My guess for larger projects is again economics: concrete is cheaper for large projects, since once a form is built (which isn't a lot of effort, depending on the shape) it really just needs to be poured, whereas the effort for bricks scales pretty much linearly with size. However, since the inital effort for concrete forming/pouring is somewhat time-intensive, I'm guessing for smaller projects brickwork is a tad more efficient (and more stylish in today's culture). There's also something to be said for the portability of concrete in a slushy form, compared to the ginormous rigid volume occupied by a massive brick. Virogtheconq 17:02, 28 October 2006 (UTC)

I said lego, but I meant something more like a profile, so that at any point the water would have to go up, which it won't if it's rain). The tight fit of the incas and the mediaeval churches was a lot of work, but with today's technology, surely we can make bricks that are exact copies of each other (within a very small tolerance, I mean). If such bricks are thus tightly packed, the joins would be no less watertight than the brick itself (unless they are coated, when they would be even more watertight). Btw, I didn't mean large bricks. They could be the same size as standard bricks. The advantage is that anyone can build such a wall, at a speed of just a few seconds per brick. A 3x3 m wall contains about 500 bricks and would take about half an hour to build. Now that's fast, and with the high cost of labour that would mean a huge saving, especially if you don't need to hire a professional. DirkvdM 08:50, 29 October 2006 (UTC)

In a region with freezing and thawing, water between the brick courses would expand when it froze, de-stabilizing the structure. Mortar could keep the moisture out. Edison 22:59, 29 October 2006 (UTC)

Bricks are somewhat porous, so don't they have the same problem (internally)? Anyway, my assumption was that we could make bricks with very narrow tolerance margins, so any water seeping through (if any, given the surface tension of water) would only form a flimsy layer. Also, a wall made of loose bricks might be more flexible, although I'm not sure if that doesn't contradict the aforementioned assumption. DirkvdM 10:36, 30 October 2006 (UTC)

Colon Cancer

I've got a vegetarian here trying to convince me that red meat can lead to colon cancer. This I've confirmed (at least, I've confirmed there exist doctors who believe it) online, but he further claims that it's caused by a buildup of actual undigested red meat in the person's colon, and that the average middle-aged (presumably American, since that's where we are) male has "several pounds of undigested red meat" in their colon. Should I be buying this? Black Carrot 19:30, 27 October 2006 (UTC)

According to Meat consumption and risk of colorectal cancer: A meta-analysis of prospective studies there is an association between red meat eating and increased risk of colon cancer. Eating 120 g/day of red meat was associated with an approximately 20-40% increased risk. --JWSchmidt 20:09, 27 October 2006 (UTC)

Yes, there is a risk, but no, that's not the reason. I've heard that said before, though, by some nutrition nut on TV, perhaps Gary Null. However, I do understand that a lack of fiber in the diet can leave some partially digested food stuck to the sides of the intestinal wall. I doubt if it's "several pounds", and this would include various foods, not just red meat. A healthy diet will include lots of fiber and minimize the consumption of meat (red and otherwise), as such meat is high in bad fats and bad cholesterol. Fish and vegetable fats and cholesterol are actually good for you, though, so eat plenty of those (like olive oil and avocados). StuRat 20:25, 27 October 2006 (UTC)

If anyone tells you your bowels are lined with undigested food, please label all past and future health and science advice from that person as absolutely worthless. Surgeons look at bowels every day. All it takes to clean you completely out is one bottle of mag sulfate. The bowels are so cleaned out you can shine a light through the walls. The obsession with whether your bowels are really moving everything through is classic American folk medicine, like the French with their livers and the Malaysians with koro. alteripse 21:30, 27 October 2006 (UTC)

Trying giving up all meat for a week or two, then see how you feel. If your guts feel cleaner, if you have more energy, if your bowel movements are easier, it might be something worth keeping up over the long run. Nevermind what doctors, scientists, and vegetarian health nuts have to say. -- Chris 23:36, 27 October 2006 (UTC)

Yeah, doctors and scientists have no idea what they're talking about. I can be serious though in saying "vegetarian health nuts have no idea what they are talking about." "Several pounds" sounds like another "figure not looked up, but made up"—have you ever seen the inside of a sigmoid colon? It isn't that big. Grab a several-pound ham and decide if you could fit it in there. Another activity would be to ask him what kind of undigested material would be in his colon if he ate several pounds of corn—if we're talking about food items that are not digested very well, then vegetable products and rocks are probably top on the list. X (SUPERDESK|Help me improve) 04:19, 28 October 2006 (UTC)

You could easily fit several pounds of meat into the sigmoid - it's able to distend to an amazing degree. However, as has been stated, anyone who is familiar with colonoscopy can tell you that pounds of meat are not in the average colon. I mean, thousands of colonoscopies are done every day in which the colonic walls are directly visualized and meat is not found. InvictaHOG 15:20, 28 October 2006 (UTC)

BTW, the question just stated "colon" (the entire large intestine), so why are we restricting the answer to the sigmoid colon only ? StuRat 15:55, 28 October 2006 (UTC)

I feel that the phrase "vegetarian health nut" is perjorative, and has no place on this reference desk. We vegetarians think very carefully about what we eat, and our longevity proves that we have some sensible ideas. --G N Frykman 08:42, 28 October 2006 (UTC)

I suppose it depends on the interpretation. If taken to mean "all vegetarians are nuts", then I agree. If taken to mean "this person is a nut, and also happens to be a vegetarian", then that's not so bad. StuRat 15:40, 28 October 2006 (UTC)

Well, looking back over the comments, it seems to take three forms - The first was the original comment about the guy on TV, who might well have been a nut, the second was a later comment about "scientists, doctors, and vegetarian health nuts", which looks like it was meant to be more playful than anything else, and the third was Mac Davis commenting on the shameful prevalence of urban legends in our society. Not that it much matters, but since you brought up the question, I figured I'd mention that the answer is right there. Regarding my friend, he's not really a health nut. And I'm not yet convinced he's wrong. The restriction of the answer to the "sigmoid colon", which I've just discovered is a rather small chamber right at the end of the real colon, seems a bit odd. Or is that a normal way of referring to it? Looking a the picture, I could actually imagine quite a bit of stuff gunking up the large intestine itself, without preventing flow entirely, especially having been forced to sit through all those videos of gunked-up heart tubes. Perhaps even several pounds of stuff, though I'm not good at estimating weight. Also, (the pictures, not the article) seems to suggest that there really is a surprising amount just sitting there being gross, though I'm not sure that's a reliable source of info. So, I'd like to restate my question slightly. 1) Given the entirety of the large intestine, how much non-useful (since I realize some slime is good for you) gunk does a normal person have, 2) How much is made up of undigested food, 3) Which foods would contribute to that (we currently have corn and meat as potential contributors), 4) Does it impair functioning, 5) If it isn't a buildup of rotting food that does it, how does meat contribute to cancer, and 6) How did you arrive at your answer? I eagerly await your further replies. Black Carrot 18:45, 28 October 2006 (UTC)

How much clearer can we make it? There is no build-up. Every day, thousands of surgeons and gastroenterologists look directly at, through, and in people's colons. There is no "build-up" that is sitting there without moving through each day as you defecate. All it takes to make you clean from one end to the other is a single dose of a cathartic, the same way people are prepared for surgery or colonoscopy. And we are not just talking about the sigmoid colon, but the entire small and large intestines. Anyone who tells you otherwise is full of crap (paradoxically, so to speak). The second issue, which is whether meat-based diets incur a higher risk of colon cancer, is an entirely separate issue that does not involve visible "build-up" anywhere. Anywhere. alteripse 04:00, 29 October 2006 (UTC)

It's not clear how meat causes cancer. Here is one article on it: . Another possibility is simple replacement. That is, people who eat large quantities of meat tend to eat fewer fruits, vegetables, whole grains, etc., and thus miss out on the cancer protection effects of those foods. StuRat 03:36, 29 October 2006 (UTC)

Re the replacement theory, that wouldn't mean that meat causes cancer, would it. It would be the absence of other necessary dietary ingredients that's the problem, not the presence of meat per se. No? JackofOz 09:10, 31 October 2006 (UTC)

the word for when stuff feels nice

hello, hope you can help, its driving me mad. what is the word for the study of when tangible objects feel nice. not in a dodgy wierdo way, but when car doors clunk well, switches switch securely, and hand tool type things are nice and heavy. my computer mouse feels plastic and rubbish; my new bottle opener is made of some grippy metal feels sort of well balanced. its not ergonomics, but is something like that............ please, thankyou, lovely people, etc simon

That was the word I was going to use. It's also "farfignuten" in German and "consay engineering" in Japanese (I have no clue how either is spelled). BTW, this question belongs on the Language Ref Desk. StuRat 20:28, 27 October 2006 (UTC)

You mean Kansei Engineering?

Yes, that it. I've never seen it in print before now. StuRat 23:38, 27 October 2006 (UTC)

Is it just me, or does that article not say anything concrete? It is as if our article on Mezcal would go like: "Mezcal is a potion that can make people happy. Since it was introduced, the world has become a better place."  --Lambiam 00:38, 28 October 2006 (UTC)

Yeah, that article is a little weak. ike9898 04:41, 28 October 2006 (UTC)

Well engineered. Neat! Nice! 8-)--Light current 20:48, 27 October 2006 (UTC)

Solid, smooth, cool 8-)--Light current 21:44, 27 October 2006 (UTC)

Tactile? Clarityfiend 21:45, 27 October 2006 (UTC)

Did you check the article on "haptic"? — Sebastian (talk) 21:55, 27 October 2006 (UTC)

Or for that matter, the synonym of septic? X (SUPERDESK|Help me improve) 04:11, 28 October 2006 (UTC)

Sometimes, I've heard the things you mentioned described as being satisfying. ike9898 04:39, 28 October 2006 (UTC)

I know the feeling. The word 'snug' also comes to mind. Something that fits snugly in your hand or a (backpack) buckle that clicks without the need to use much force, but doesn't rattle either, meaning it's a perfect fit. But 'heavy' is also an important word here. Like a Mac mouse. Or a door that refuses to slam, but instead makes a civilised 'clonk' sound, the way doors of heavy expensive cars do. You don't need to close it explicitly, just give it a push (momentum) and it continues on its way and when it closes encounters the 'padding' of first the lock and then the weather strip - neither too hard nor too soft. Just 'snug'. But that's too general a word. 'Solid' also comes close, but both words are too general. DirkvdM 12:04, 28 October 2006 (UTC)

"Phat" or "Da bomb." Edison 17:00, 28 October 2006 (UTC)

So that's why some people call their girlfriends "phat"? --Wirbelwindヴィルヴェルヴィント (talk) 17:24, 28 October 2006 (UTC)

That stands for "Pretty, Hot, And Tempting". StuRat 07:56, 29 October 2006 (UTC)

dynamic motion

A girl running at a constant speed of 2.3 m/s in a straight line throws a ball directly upward at 4.4 m/s. How far will she travel before the ball drops back into her hands? Ignore air friction.—Preceding unsigned comment added by 24.99.59.96 (talk • contribs)

Do your own homework. If there's a specific concept you need help grasping, we can aid you. We won't your homework questions for you, though. -- Consumed Crustacean (talk) 20:49, 27 October 2006 (UTC)

Word. Since it probably won't occur to you to politely rephrase the question in a more general form, or better yet, since it's a fairly standard physics problem, search for it yourself, here's where you can find the answer: Equations_for_a_falling_body. Black Carrot 21:10, 27 October 2006 (UTC)

How long does it take for the ball to accelerate from 4.4 m/s, to 0, and to 4.4 m/s again? And how far can the girl run in that period of time? --Bowlhover 22:27, 27 October 2006 (UTC)

In US English, that's "How long does it take for the ball to decelerate from 4.4 m/s, to 0, and accelerate back to 4.4 m/s again ?". Note that the girl's motion does not matter, since the ball takes on the exact same motion. StuRat 23:06, 27 October 2006 (UTC)

I don't think it's a US v british thing, it's a science v common usage thing. The scientific defination of acceleration is "change in velocity" speeding up, slowing down, changing direction are all accelerations. Theresa Knott | Taste the Korn 23:12, 27 October 2006 (UTC)

Yes, but it's customary in the US to refer to negative accel as decel. It sounds as strange to us to say "accelerate down to zero" as it would be for you to say "heat the solution down to absolute zero" or "pay the customer -$15". StuRat 23:26, 27 October 2006 (UTC)

Acceleration/deceleration in whose frame of reference? Granted this is a more simple situation, but there are many cases where an object will be appearing to slow down from one person's viewpoint, yet speed up from another person's viewpoint. Acceleration in a scientific context, like, say, you might find on a science reference desk, is merely the rate of change of momentum with respect to time, a vector quantity. For a fixed-mass object, it's the rate of change of velocity w.r.t. time, also a vector - with magnitude and direction, where direction is often denoted by a + or -. In this situation (due to approximation for this type of science question), the acceleration is a constant, the ball is accelerating downwards due to a constant force - gravity. Note that in forming the equations of motion, you do not have to treat the slowing down to zero speed and speeding back up to 4.4 m/s as separate parts of the trajectory. Richard B 00:33, 28 October 2006 (UTC)

StuRat, the question asks "how far will she travel before the ball drops back into her hands". So the girl's motion does matter. --Bowlhover 23:30, 27 October 2006 (UTC)

I should clarify my statement. The girl's motion does not matter in determining how long it will be until she will catch the ball. However, her motion does matter in determining the distance she will travel in that time. StuRat 06:17, 28 October 2006 (UTC)

Air resistance (plus a small gust of wind) will cause the ball to lose forward speed and clunk her on the head. Then she will run home and do her own homework. Edison 17:05, 28 October 2006 (UTC)

Wow, you sure told him. Good thing he didn't say "ignore air friction", or you'd look a little silly. Black Carrot 18:20, 28 October 2006 (UTC)

Do your own homework.But I will give the concepts

1. Consider the Initial Upward Velocity of the ball as b
2. We know that v=u+at . And re arranging you get t=(v-u)/a In this case, v=0 and a=-g and u=b
3. So time needed for the ball to come to rest when thrown upward is t=(0-b)/-g=b/g
4. So time needed for the ball to come again to the ground is time=2b/g
5. Time is 2*4.4/9.8
6. The horizontal velocity of the girl is 2.3
7. Velocity = Displacement/Time
8. Displacement = Velocity x Time
9. Distance covered = Displacement = 2.3 x 2 x 4.4 / 9.8 = 2 metres

I have not checked whether the ball will fall to the ground or fall in her hands.

For that you need to use a formula involving tangential values. I joined in Medical College 10 years ago. Since then I have not used these formulas. Hence I am not able to recollect the second formula that is also used to calculate the range of artillery fire, military tanks etc. ANy doubts, please leave a message in my talk page  Doctor Bruno  20:21, 28 October 2006 (UTC)

Title of doctor.

Are the following people allowed to use the title of doctor in the United Kingdom?

Dentists (with the degree BDS) Chiropractors (with the degree MChiro) Nurses (whith say Ph.Ds but practice as nurses) Podiatrists (with Bachelors degrees)

Thank you

• Dentists are doctors but their titles are 'Mister' (meaning surgeon).
• I dont think you'ld get many PhDs acting as nurses!
• I dont think podiatrists are classed as medical doctors.
• Opticians are doctors
• Chiropractors --- Im not sure, probably not

--Light current 22:35, 27 October 2006 (UTC)

• The dentist one puzzled me as my first dentist called himself Mr but my next one and the whole surgery went by Doctor. So, like medical doctors with MCh degrees who call themselves Mister, they ARE entitled to use Doctor?
• Well, I know this is fictional, but there was a nurse in ER who had a Ph.D. I wasnt sure where this matter stood
• thank you
• There are 2 new Chiropractors in town with BSc and MChiro degrees and go by "Practice Doctors" and have doctor in front of their name.

Christopher

Yes all surgeons in UK whether dental or otherwise call themselves 'Mister' (a throwback to the days when barbers used to do it).--Light current 22:45, 27 October 2006 (UTC)

That comment about nurses is pretty derogatory. Nursing is a tough profession and I'm sure I could find you handfuls of nurses with phds. Aaadddaaammm 02:42, 28 October 2006 (UTC)

• I dont think you'ld get many PhDs acting as nurses! How is that derogatory?--Light current 03:02, 28 October 2006 (UTC)

A search for "nurse phd" gives 3,850,000 pages through google. Many different programs are evidently available to gain a phd in nursing. Aaadddaaammm 03:59, 28 October 2006 (UTC)

So?--Light current 04:28, 28 October 2006 (UTC)

Opticians are doctors in the UK? In the U.S., Opthalmologists are MDs and optometrists have Doctor of Optometry degrees but opticians are technicians which may not even have a university degree. --OpusPenguin 03:12, 28 October 2006 (UTC)

Yes I believe so.--Light current 03:28, 28 October 2006 (UTC)

Anyone can use the title "Doctor" in the UK, it is not illegal to adopt that title. As has been mentioned many times on this 'desk, most British medical practitioners are not "real doctors" in the historical sense of the word, as they do not have a doctorate (like an MD). Most are Bachelors of Medicine and call themselves doctor by convention only. Its a self-imposed, honourific title that is now synonymous with their profession, but historically it means something very different. Same goes for dentists and podiatrists. Ironically enough, in your example, the only "real" doctors are the nurses with PhDs.

In the UK its only illegal to use the title to defraud, so you can go around calling yourself "Doctor Light current" if you wish, as long as in doing so, you do not try to use the title to imply you offer medical skills, services or authority. The only people that can use the title "Doctor" to offer medical services are those registered with the GMC or equivilant. Rockpocket 06:39, 28 October 2006 (UTC)

Well anyone with a PhD calls themselves Doctor in the UK. And medical doctors, who dont, do!--Light current 13:34, 28 October 2006 (UTC)

True, but only "medical doctors" are registered with the General Medical Council, hence their real title is a "registered medical practitioner". The only real "medical doctors" are those with an MD or a PhD and MB BChir/MB BCh/MB ChB/BM BS/MB BS et al. Rockpocket 18:30, 28 October 2006 (UTC)

So going by the MBBS article, it appears that UK medical doctors can start practicing medicine five or six years out from high school, is that right? Whereas in the States you need a four-year undergrad degree, four-year MD, plus a residency. Presumably we pay for all that extra education in our medical bills. Not that I personally am in any position to complain about that :-) I'm just wondering whether we get anything for it. Are our doctors smarter than UK ones? Better able to diagnose and treat unusual complaints? Has any objective comparison been made of the standard of care? --Trovatore 18:47, 28 October 2006 (UTC)

Actually I think its 7 yrs total un UK : 3 yrs medicine + surgery, then 4 yrs on the job to get the other qual. I think in the UK we get our Masters Degrees in these extra 4 yrs, but I could be wrong. Therefore

Are our (US) doctors smarter than UK ones? --

A.No.

But a masters degree does not entitle one to call oneself Doctor (as in Ph.D)

--Light current 20:29, 28 October 2006 (UTC)

Its an interesting question. I happen to work in bio-medicine and interact with med students and youngish doctors from both countries. While its not a case of one being smarter than the other, in my experience, there certainly is a difference. Firstly, in general, US medics tend to be better educated (because they have a wider tertiary education) and thus appear more learned. They also tend to be more "focussed", for want of a better word. This is because many decide to become a medic when they are older and thus more mature and also because the cost of completing an MD is the US is astronomical compared to the UK. Its not all pro-US though, the motivation of the UK medics tend to be more Hippocratic. I detect a financial motivation much more in the US students (though i suspect that is both a cultural thing and also because the financial outlay is so great.)

That said, however, this is based on observing the individuals during their training process. Inevitably, the cream rises and chaff is separated during their training, and, when you compare the fully trained medical professionals, i don't really think there is a major difference. Even if there is, its hard to control for the difference in medical systems between the two countries. If you took the British medical community and gave them the resources the private sector afford the US community, who is to say what the standard of care would be? Similarly for US doctors working within the NHS. Rockpocket 20:49, 28 October 2006 (UTC)

October 28

Helium

According to the Helium article, it the 2nd most abundant element in the universe, but not really very abundant at all on Earth. Why? Is simply because molecular helium tends to rise in the atmosphere and escape into space? Or is there some deeper reason for scarcity of He on Earth? ike9898 03:40, 28 October 2006 (UTC)

Earth's gravity is not strong enough to hold on to a hydrogen/helium atmosphere. Before life even originated, the hydrogen/helium atmosphere was blown off by the Sun's solar wind. Right now though, the helium generated by radioactive decay does escape into space (as you said). The heterosphere actually has a lot of helium. --Bowlhover 03:49, 28 October 2006 (UTC)

It is also chemically very inert so it can't get trapped like other light atoms like Hydrogen. Hydrogen is very abundant because it is trapped as much heavier water. it would be interesting to also see how much Helium is "trapped" in radioactive atoms that undergo alpha particle decay. --OpusPenguin 03:50, 28 October 2006 (UTC)

observing stars other than the sun

I know that it is possible to take pictures of the sun that actually some 'detail', that is, they show 'surface ripples' rather than just a featureless disk of light. My question is, with any existing equipment (including the Hubbel telescope), could you produce an image of a star, other than the sun, that actually shows some of this detail? If not, would this be possible with any instrument that could be built within, say, the next 25 years? ike9898 04:36, 28 October 2006 (UTC)

Yes, it is possible. For example, here are 3 pictures of the surface of Betelgeuse. I don't know if any other star's surface has been imaged, though; I'll be curious to find out. --Bowlhover 04:54, 28 October 2006 (UTC)

The fourth picture on that page looks curiously close to something done with Crayola colored pencils. Hyenaste  23:34, 28 October 2006 (UTC)

Easy, with the right budget. If the scientific world had the budget of the military such telescopes (and better) would have been commonplace now. We'd have permanent stations on other planets and all that star trek stuff. But in the real world, you'd have to wait a few years, for the Herschel Space Observatory or a few more for the James Webb Space Telescope. Not sure how much detail they will show, though. There are also plans to send multiple telescopes into space somewhere in the 2020's, that work in unison, thus getting the resolution of a much bigger telescope (albeit not the light sensitivity). With that, we could even study the surface of planets orbiting stars (provided they are not too far away). DirkvdM 12:25, 28 October 2006 (UTC)

Gel-based ice packs - removing dried contents?

I've left an ice pack in the back of my car for a while, and not only has it burst, it's dried out. The remaining contents are some kind of crystalline-type stuff, and where they've "set" in the carpet they're damned difficult to remove. Does anybody know a) what the stuff is, and b) any suggestions for removing it more effectively than water? --Robert Merkel 05:23, 28 October 2006 (UTC)

It would depend on the ice pack, but for the one I found first on Google, you can vacuum it, and it's also water soluable. What brand was your ice pack? I believe there are more than one gel used for them. --Wirbelwindヴィルヴェルヴィント (talk) 06:03, 28 October 2006 (UTC)

It really depends on the brand. Some are water-soluble, some aren't, some are toxic, some are less toxic. I'd be careful when cleaning it up. Virogtheconq 07:05, 28 October 2006 (UTC)

Questions about salt water

I am writing about salt water. Questions:

• Is salt water suitable for bathing (on a consistent basis)? Will soap and shampoo lather in salt water?

• Is salt water be suitable for cleaning benches, cooking implements, and crockery?

• Aside from the problems of installing dual reticulation where it doesn't presently exist, would there be issues in transporting salt water to homes (i.e., in corrosion of pipes/machinery - but I think most reticulation pipes are concrete or plastic, not metal...)? BenC7 07:06, 28 October 2006 (UTC)

If there is no problem of corrosion on the way to the homes, there would be huge problems within the home. Most taps, piping etc. are made of metal. --liquidGhoul 07:20, 28 October 2006 (UTC)

Soap is rather ineffective in salt water, which is why it makes sense to pre-rinse clothes you've been sweating in before you wash them (sweat is salty). There is a special kind of soap for salt water that I tried once, but I wasn't impressed at all. Apart from the soap not working properly, if you rinse something with salt water and let it dry, some of the drying will be through evaporation, leaving a salt layer, which will not be desirable in most cases. DirkvdM 12:39, 28 October 2006 (UTC)

Some soaps do fairly well. The "Joy" brand of detergent is a favorite among sailors, and being one myself I can personally attest to it working fairly decently in seawater. Not that there's much you'd want to clean in salt-water apart from dishes. --BluePlatypus 18:12, 28 October 2006 (UTC)

All (nice) salt water beaches have fresh water showers. Salt is yucky on the skin. The new trend is for saline swimming pools, but this concentration is much less than ocean water. --Zeizmic 14:40, 28 October 2006 (UTC)

Soap does not lather in saltwater. I've heard that Ivory is best - but that is likely because it floats so it is hard to lose it when bathing in the ocean. As for transport, saltwater can be effectively transported. The University of Hawaii is expanding a project that transports cold saltwater from deep in the ocean to the surface where it is used to cool buildings before being sent back to the depths of the ocean again. --Kainaw 15:11, 28 October 2006 (UTC)

In places where fresh water is scarce, one approach is to bathe or wash clothes or dishes in salt water, but then rinse in fresh water, to eliminate the salt water residue. Food may also be cooked in salt water. Note that salt water from the sea has life forms and debris in it, too, which can clog pipes. Filtering the water helps, but the filters will soon clog, as well. One approach is to clean the pipes using a "pig", a large slug rammed down the pipe to scrape the sides clean, on a regular basis. StuRat 15:26, 28 October 2006 (UTC)

Food can be cooked in salt water? What? Doesn't the food (say, rice) absorb a lot of the salt, making the food extremely salty? BenC7 01:34, 29 October 2006 (UTC)

Yea, it wouldn't work for some foods that absorb lots of water; like pasta, rice, and hot cereal. But you could boil meat, fowl, fish, potatoes, eggs, etc. in salt water without making them too terribly salty. StuRat 03:07, 29 October 2006 (UTC)

looking for the name of a thing used to view still photos moved by a crank

Hello,

Could somebody please help me with the name of a picture viewing machine, widely prevalent in India in the 1960s and 70s (maybe earlier and in other places too) where a record used to be played on a grammophone and kids looked through peepholes, 5 or 6 of them around a cylindrical (or polygonal) base. inside were pictures pasted on a coaxial polygon which rotated as the operator turned a crank. the whole thing rested on a table or tripod and could be packed and carried on the head.

will a picture along with the name be too much to ask for?

i have tried bioscopes but the images i'm getting on the net are not the ones i mean.

thanks in advance for the trouble.

regards

Kushal, Chennai, India

a zoetrope. Xcomradex 10:01, 28 October 2006 (UTC)

A Mutoscope is probably closer to what you're thinking of.

Atlant 21:26, 28 October 2006 (UTC)

Yes thats what I was thinking, but I called it an orthoscope. (which doesnt exist)--Light current 21:48, 28 October 2006 (UTC)

Papain, Bromelain, Ficin and Actindin

I am doing an experiment where I am seeing what enzyme will tenderize meat the fastest. I need a concentration/percentage that is very close. For example, if the sample of papain contains 97% of papain as the main ingredient,then ficin should be very close to that amount.

I would appreciate if anyone would know where I could purchase these digestive enzymes:

Papain (Papaya), Bromelain (Pineapple), Ficin (Figs) and Actinidin (Kiwi). Preferrably in powder form, since it would be hard to know the amount of the enzyme in each piece of fruit.

The problem I am finding is that the Health Stores only carry Papain and Bromelain and some of the biochemical companies sell only industrial size.

Would any universities carry them?

Thanks,

JDC

This was already responded to on the 27th. If you want to study the activity of the enzymes, you'll need to get them in an active form, usually frozen or (sometimes) freeze dried. Your school may be able to arrange a purchase of small amounts of the enzyme from Sigma-Aldrich (which is where I go for most of my various enzymatic needs). Good luck! – ClockworkSoul 14:00, 28 October 2006 (UTC)

Neutrinos and Antineutrinos

Hello, I was reading the Misplaced Pages article on the neutrino and noticed the mention that it might be the same particle as the antineutrino. There wasn't a very good explanation as to why this would be so that I could find, so I was wondering if someone could give an explanation. Thanks! Andromeda321 16:00, 28 October 2006 (UTC)

This is difficult ton understand without some background in particle physics and special relativity. Assuming that you know a little bit about it, I'll give it a try: According to the principle of C-symmetry, every elementary particle has a corresponding antiparticle, which has the same mass, but differs from the former in that all charge-like quantum numbers have opposite sign. A electron, for example, has only electromagnetic charge, of value -1, and its antiparticle, the positron hence has electric charge +1. An up quark has electric charge +2/3 and colour charge red, green or blue, and an anti up quark hence electric charge -1/3 and colour charge antired, antigreen or antiblue. Now take the photon, which has no charge with respect to any of the fundamental interaction electromagnetism, weak interaction and strong interaction. Reversing the sign of 0 (no charge) gives 0, so there is no contradiction in assuming that it is indistinguishable from its antiparticle: as it turns out the photon is its own antiparticle. Now, is the same true for the neutrino, which also has no electric or strong charge? The weak interaction has the strange feature of CP violation: it can distinguish between a neutrino "spinning clockwise" (having helicity -1) and one "spinning anticlockwise". Now oe wonders whether the difference between neutrino and antineutrino is really due to them being different particles or only because they have different helicity. One possibility is called Dirac neutrino, the other one Majorana neutrino. This difference becomes meaningless when the neutrino is massless because then it travels at the speed of light, and its helicity is the same in all frames of reference, while now, that we know that neutrinos have mass, one can imagine "overtaking" them by a Lorentz boost and see how they interact as seen from that fram of reference. About here, my memory of my particle physics course taken years ago gets a bit too fuzzy and I better stop and let somebody else continue. Simon A. 16:36, 28 October 2006 (UTC)

Variables

Hi there

is there a simple and clear way of understanding dependent variables and independent variables? I am 49 years of age, studying for a Single Hons Degree in Psychology, but Research Methods defeats me - especially understanding what these variables are and how to use them. Have had discussions with fellow students and a one to one session with a student taking his Phd. Am tearing my hair out, given so many examples but do not understand any of them. Please somebody help this thick old woman!!!!!!!!! Carole D

Did you try reading dependent variable and independent variable? Independent variables are ones you set for experiements. For example, if you want to use placebo, that's an independent variable. The result from using placebo, is the dependent variable. --Wirbelwindヴィルヴェルヴィント (talk) 17:28, 28 October 2006 (UTC)

Suppose you want to test the hypothesis that people who study more obtain better grades for their exams. You know that students spend on the average 25 hours or so per week on their study, but some spend much less time and some spend more time. So you randomly select a group of students, and find out for each: (A) how much time per week they studied, and (B) what grade they got. These two data are variables. So for each student you have two variables: X = hours/week and Y = grade. The hypothesis is that Y depends on X: a higher value of X gives rise to a higher value for Y. Then, for the purpose of testing your hypothesis, Y is called the dependent variable. (Maybe it turns out that the hypothesis is rejected, and that the value of Y does not depend on X. Still, for your test, it is the dependent variable.) The other variable, X, is the independent variable.

In this example there is only one independent variable. But perhaps you have also collected data about how long the students sleep each night, because you also think that you need enough sleep to get good grades. Then you have two independent variables.

See for more information also Variable#In applied statistics, Control variable, and Experimental design.  --Lambiam 17:36, 28 October 2006 (UTC)

control system

even though i could get lot of information about control system but the subjects which are in continution to it like Discrete Control System,Optimal control system, Adaptive Control System,Computer Adied Designe Of Control System , i am unable to get information about these subjects. can you suggest me how to get the notes of these subjects.

202.63.109.234 16:52, 28 October 2006 (UTC)imran (A.C.E.T)

Those sound like master and Ph.D. level topics, as I am an engineering student and the senior level courses only go up to systems and control. Your best bet is at a university library. --Wirbelwindヴィルヴェルヴィント (talk) 17:30, 28 October 2006 (UTC)

I agree. It is really a vast field, and you should try to find texts corresponding to your needs, interests, and background. I assume you are familiar with the material on Control Systems at Wikibooks. Perhaps our articles on Digital Control, Control theory, Real-time control, Optimal control, Adaptive control, Control engineering, and MATLAB, also following promising links in the "See also" and "External links" sections, give you some material to mull over in the meantime, and suggest some pointers to follow.  --Lambiam 17:58, 28 October 2006 (UTC)

how to create an artificial force field

respected sir, im an engineering student and i would like to know how to create an artificial force field. for many good reasons keeping in view the defence system of every country.by using artificial force fieldis it possible to convert the energy grabbed by the object to the potential energy of the system and can be re imparted energy to thre object.its a very typical question.so i would be needing ur help to get out of this problem.hope to seek the answer soon. —The preceding unsigned comment was added by Punitmalpani007 (talk • contribs) .

Did you read our page on force fields? There is a section called "Research and development" that answers your question. And please sign your stuff with 4 tildes, or ~~~~. --Wirbelwindヴィルヴェルヴィント (talk) 17:33, 28 October 2006 (UTC)

In a practical sense, there's no real way to create a force field that might repel/capture objects on a scale that could defend a country (at least for the next twenty years or so). The energy requirements for (see magnetic levitation for a not-very-applicable example) are just too darn high. If you're more interested in the theory of trapping matter, laser trapping might be a good article to look at too. Virogtheconq 20:45, 28 October 2006 (UTC)

Weight

I'm thinking about making yeast bread, but I like to buy my food by price-per-unit-weight. How much mass does yeast consume in producing carbon dioxide, assuming the standard practice of letting the dough double in volume? What would be the most cost-effective way to do this? Black Carrot 18:52, 28 October 2006 (UTC)

I think you can safely assume that the yeast consumes a negligible amount of the sugars in the hour or two that it is actively fermenting.

Atlant 21:30, 28 October 2006 (UTC)

Agreed. The gases which are given off by the yeast and exit the bread (after the "bread squeeze" phases) would be the only source of lost mass in the bread. I'm thinking that weight would be under one gram. StuRat 02:45, 29 October 2006 (UTC)

Complete proteins

I have often heard that soy is the only vegetable source of complete protein; however, I have also heard this claim made for certain grains such as buckwheat, quinoa, and amaranth. I found a ref for quinoa, but am having trouble for the others. Does anybody know of any reliable sources that can tell me once and for all which, if any, vegetable proteins are complete? --Ginkgo100 20:58, 28 October 2006 (UTC)

To clarify, I am also looking for a ref for soy, because all I can find on the Internet is commercial bodybuilder website. --Ginkgo100 21:00, 28 October 2006 (UTC)

If you don't find your answer elsewhere, then you might want to try to find a copy of Diet for a Small Planet by Frances Moore Lappé; this book discusses which foods combine well together to provide complete nutrition.

Atlant 21:32, 28 October 2006 (UTC)

For clarification, may we assume in a dietary context a "complete protein" is one which contains all essential amino acids? alteripse 14:40, 29 October 2006 (UTC)

Valence Electrons

How many valence electrons does oxygen have? 71.97.11.77 21:25, 28 October 2006 (UTC)nicholassayshi

Six. Why do you ask? Theresa Knott | Taste the Korn 21:51, 28 October 2006 (UTC)

It doesn't say in the web site. 71.97.11.77 22:08, 28 October 2006 (UTC)nicholassayshi

Here's how you find out: Look at the table for valence shells. Find the number of electrons in element (8 for oxygen). So 8 minus the number of electrons in shell one is 8-2 = 6. So you have a full first shell, with 6 electrons left. The 6 remaining electrons is less than the max of the second shell, thus it doesn't go to a third shell, thus the valence shell is the second shell, with 6 electrons. Hope that makes remotely some sort of sense. --Wirbelwindヴィルヴェルヴィント (talk) 22:40, 28 October 2006 (UTC)

Shimmering tarmac on a hot day

Who can explain to me why, when you look along a tarmac or asphalt road on a hot day, you see a shimmering, mirrored effect in the distance. I presume its heat related and is the same effect that produces shimmering in the desert, but what is the exact mechanism? Thanks. Rockpocket 21:26, 28 October 2006 (UTC)

See Mirage; that article is pretty complete and speaks directly to your question.

Atlant 21:33, 28 October 2006 (UTC)

Amazing. Thank you, i never realised that was what the word 'mirage' referred to. Rockpocket 21:36, 28 October 2006 (UTC)

October 29

Cell Cycle of a Human Brain Cell, Human Liver Cell, and a Yeast Cell

How long is the cell cycle of a human brain cell, a human liver cell and a yeast cell? Thanks very much!--208.65.244.21

Brain cells last for your entire life. Liver cells probably live for a couple of weeks, but I'm not sure. Yeast cells don't reproduce by mitosis or binary fission; they reproduce by budding. --Bowlhover 01:56, 29 October 2006 (UTC)

There is some dispute about neuron lifetimes I think. Neurogenesis X (SUPERDESK|Help me improve) 08:00, 29 October 2006 (UTC)

And remember, regardless of how long the cell itself lasts, or appears to last, the actual chemicals (proteins, etc) they are composed of are continually being replaced. --jjron 10:52, 29 October 2006 (UTC)

science-fiction weapon

Hi. I was wondering if someone could give me a list of all the future weapon that are currently been researched(doesn't have to be complete). Not new model, but new things that you might expect in a science-fiction movie like raygun or forcefield. Thanks

Rail gun, coil gun, particle weapons, frangible ammunition: . 07:40, 29 October 2006 (UTC)

Directed-energy weapon has a lot of links. —Keenan Pepper 08:28, 29 October 2006 (UTC)

Iron and Steel ingredients

I was trying to find out what the proportions are of iron ore,coke,and limestone were needed to produce a tonne of iron. Then what was needed to make this into steel .

Iron is a chemical element, meaning it contains nothing else but iron, however, there are various formulations with differing levels of impurities, like pig iron and wrought iron. Are you asking about what is needed to smelt iron ore to produce one of these ? Steel, on the other hand, is various alloys of iron and other elements. To answer the question on the ingredients in steel and the components needed to produce it, we would need to know which type of steel you mean, for example, surgical stainless steel. StuRat 12:20, 29 October 2006 (UTC)

Please do your own homework.

Welcome to the Misplaced Pages Reference Desk. Your question appears to be a homework question. I apologize if this is a misinterpretation, but it is our aim here not to do people's homework for them, but to merely aid them in doing it themselves. Letting someone else do your homework does not help you learn nearly as much as doing it yourself. Please attempt to solve the problem or answer the question yourself first. If you need help with a specific part of your homework, feel free to tell us where you are stuck and ask for help. If you need help grasping the concept of a problem, by all means let us know..

Use the blast furnace formula, then include the Molar masses of the substances, then factor down to 1 t of product. It's not really a chemistry question, rather one of Maths. Englishnerd 14:12, 29 October 2006 (UTC)

Maps of the universe

A special satalite was lanched to make a Cosmic Ray map of the universe. Havw any othe maps of the universe been made based on the spectrum and presence of the elements? Adaptron 15:47, 29 October 2006 (UTC)

Energy Dinsity

I would like to find out the energy dinsity per gram and kilogram of wood,petrol,natural gas,butter and coal.justin chung 29/10/06

I believe that you mean "density." Start by reading the article calorie.

B00P 16:15, 29 October 2006 (UTC)

Did you try our article on energy density? Everything you need is there except for butter. --Wirbelwindヴィルヴェルヴィント (talk) 16:18, 29 October 2006 (UTC)

"Energy dinsity" = How loud and annoying a form of energy is. For example, rap music played on a 2000W mega-bass car radio (so everyone in the area hears it) would rank very high in "energy dinsity". :-) StuRat 16:22, 29 October 2006 (UTC)

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