Wikipedia:Reference desk/Archives/Science/2006 September 9

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September 9

Sandalwood characteristics

I am a hobbyist and would like to make a gavel out of sandalwood for presentation to a friend but I do not know if Sandalwood can stand knocking especially in a cold country. I have searched through the various relevant topics in Wikipedia as well as on the Internet, without success. Would appreciate some advice on this or some links from which I can obtain such information. Thank you. 218.186.8.12 01:54, 9 September 2006 (UTC)Kenneth Ang

Will your friend be using his gavel outdoors in the winter? In India, the government owns all Sandalwood trees, you'll have to deal with their infinite beaurocracatagcauauaucy to get your wood. Or, you could probably bribe someone.....

The friend in North America will be using the gavel during Lodge Meetings. Anyway if I have to go through endless beaurocracy just to get a piece of wood big enough to make a gavel, I'd rather not. All the same, it will be interesting to find out if Sandalwood will crack or split with constant knocking, as with gavels.

If that was the case, they might have made sandals from it, but no, sandalwood is from a different root. I have various items made of sandalwood, and it seems to split quite easily through drying out.--Shantavira 12:31, 15 September 2006 (UTC)

Mechanism of thermoception

What is the mechanism in which thermoception occurs? I remember it being "rapid coagulation of certain enzymes," to quote Dean Edell perhaps incorrectly or in the wrong context from my memory of two years ago. — [Mac Davis] (talk) (Desk|Help me improve)

That isn't really an accurate description. Research into mammalian thermosensation has advanced quite rapidly recently. Briefly, ion channels of the transient receptor potential (TRP) family, are found in the nerve endings of primary afferent fibers. When activated by a ligand that we perceive as hot (such as capsaicin) or cold (such as menthol) the channel opens and allows an influx of ions. This, in turn, causes an action potential which we interpret as "hot" or "cold". These same receptors appear to mediate the response to temperature itself also (as opposed to chemicals we perceive as hot or cold), though the exact mechanism of channel activation is currently unknown. TRP channels exhibit distinct thermal activation thresholds in mammals (>52 degrees C for TRPV2, >approximately 34-38 degrees C for TRPV3, >approximately 27-35 degrees C for TRPV4, <approximately 25-28 degrees C for TRPM8 and <17 degrees C for TRPA1). You can read more about this in the scholarly literature [1] [2] Rockpocket 06:04, 9 September 2006 (UTC)

The full text of Sven-Eric Jordt, David D McKemy and David Julius. Lessons from peppers and peppermint: the molecular logic of thermosensation Current Opinion in Neurobiology 2003, 13:487–492 is available on the net, and is a worthwhile review as a basis. Enzymes do not seem to be involved, nor any coagulation - in the ordinary "permanent" sense - unless the term "coagulation" was used rather unconventionally as a word to convey the idea of a (reversible) structural change in a protein. In that sense, temperature-related perturbation in protein structure, as opposed to chemical receptor interactions, may well be the basis for the ion channel changes, but details are lacking. Interestingly, we seem to have about 30 "coldness" nerves for every "warmth" nerve - why? --Seejyb 06:43, 9 September 2006 (UTC)

Dangerous Combination?

Hi, I would like to know please, if the Medications listed below, taken as a daily Regiment (45 Yr. Old Female) Pose any potential interactions, and or health risks? Any Feedback will be Greatly Appreciated. Thank You For Your Time And Concern.

Sincerely,
MmHm

• TEMAZEPAM
• TRAZADONE
• RITALIN
• LEXAPRO

• This is the kind of thing you should ask a doctor as indicated at the top of this page. - Mgm|^(talk) 09:00, 9 September 2006 (UTC)

A pharmacist could also answer your question over the phone. BenC7 09:16, 9 September 2006 (UTC)

Well, they are all different classes of medications and it would probably depend on the doses and underlying illness. Certainly, any one of them could have serious side effects depending on how they are used and the individual taking them. If the Lexapro is taken for depression, the trazodone for sleep, the temazepam for anxiety, and the Ritalin for ADHD, and a person has all four problems, then it seems reasonable. However, one problem might occur if the Ritalin is being used to make a person more awake during the day while the trazodone is being used at the same time for sleep, then there are probably better ways to get this benefit. As you must understand, it's simply not possible for anyone here to know enough about the clinical situation you are involved in to competently give you an answer. In the end, the prescribing doctor(s) are your best source of information. InvictaHOG 10:10, 9 September 2006 (UTC)

As always, it's always best to consult with your physician, because all drug interactions must always be considered in the context of the individual patients' health profile. However, there is an online source for checking documented drug interactions-- use at your own risk: Check Interactions - DrugDigest--Mark Bornfeld DDS 13:32, 9 September 2006 (UTC)

Physics problem - not homework

I must be doing something wrong working out this problem:

A 1200kg car goes around a corner banked at an angle of 14° travelling at 80km/h. Is a friction force needed to keep the car on the road? If so, how much?

I am using the equations (tan θ = v²/rg and F_centripetal=mv²/r). Is there enough information in the question? BenC7 09:14, 9 September 2006 (UTC)

I would think the radius of the turn would also be needed, unless it cancels out in the calculations. StuRat 10:57, 9 September 2006 (UTC)

Assume a radius of 20m, another one of 200m, do the calcs, and if they aren't the same the problem is the problem, which it seems to be. --Seejyb 12:58, 9 September 2006 (UTC)

Our practical experience makes us worry that the car might go off the road to the outside of the corner. But in the artificial situation of no friction, the car could also slide off the road to the inside of the corner. Consider both possibilities. --Gerry Ashton 13:41, 9 September 2006 (UTC)

If you assume an infinite radius, the answer is yes, because the car would eventually slide down off the ramp. If you assume a very small radius, the answer is again yes, because the car would then immediately slide off the top edge. There needs to be a very specific radius for this question to make sense. I think? Maybe I'm being physically naive.  freshofftheufoΓΛĿЌ  15:25, 9 September 2006 (UTC)

To further explain my point: Since the answer is "yes" in both extreme situations, let's calculate the friction. Since a ramp with an infinite radius doesn't exert any force on a car that a straight ramp wouldn't, the amount of friction needed to keep it from sliding down is equal to the amount needed when the car is on the slope at stand-still. In case of a small radius, the only thing that you can calculate is that the amount of friction needed approaches infinity. The only other case to consider is the one where friction isn't required.  freshofftheufoΓΛĿЌ  15:31, 9 September 2006 (UTC)

Whether the track is banked or not, you still need the radius of the curve that the car is following.--Light current 21:15, 9 September 2006 (UTC)

Yes, but in that case, the answer is "yes" if the speed is over zero for every radius less than infinity.  freshofftheufoΓΛĿЌ  08:13, 10 September 2006 (UTC)

Although there is not enough information to say that the frictional force is x Newtons - we can work out a relationship showing how the frictional force varies as we change the radius of curvature. Use r = v² / (g tan θ) to work out the limiting case where no friction applies - i.e. that the normal reaction force from the road surface is sufficient to both balance the object's weight, and accelerate the object with centripetal acceleration of v²/r. For θ = 14º, g = 9.81 m/s², v = 22.22 m/s; r ~ 202 m. Lower than 202m and the object needs friction pointing up the slope, greater than 202m and the object needs friction pointing down the slope. By very rough back-of-the-envelope calcs (and I might have made a mistake), I think the frictional force is; F ~ 2848 - 575000/r F is in Newtons - and the positive direction is up the slope, r is in metres. Note that this is pretty approximate, and it's more accurate if you keep the thetas, m's, v's g's in the equation, rather than multiplying and simplifying as I've done. Note also, that if F = 0, the above equation gives r = 202m, as I had before.Richard B 21:10, 10 September 2006 (UTC)

cholesterol reducing spreads.

Hi, is it better to eat a cholesterol reducing spread (such as benecol) to lower your cholesterol level, or does the actual eating eating of the spread supply you with more cholesterol anyway so you are only reducing the cholesterol from the spread?

There are two cholesterol goals, keeping bad cholesterol low and good cholesterol high. Avoiding all cholesterol only handles the first part, while a product like Benecol has the potential to do both. StuRat 10:43, 9 September 2006 (UTC)

Flash cubes

Back when instant compact cameras were a novelty (mid-70s) some flash cube types required no battery but the camera was just shorting two leads connected to the respective cube face lamp. The lamps (behind the cube faces) contained a metal wool that ignited upon shorting the respective wires and produced the flash. I never understood the principle involved in igniting a ball of metal wool by shorting the wires leading into it. Anyone know?

I believe the "wool" was a flammable magnesium alloy which, when heated by the electrical current (like a filament), rapidly burned in the presence of oxygen from the air. This puts out a bright, but short-lived, flash of light. See flash (photography). StuRat 11:50, 9 September 2006 (UTC)

Is it possible that the battery was built into the film pack, so some people might not have noticed that the camera was equipped with a battery? --Gerry Ashton 13:43, 9 September 2006 (UTC)

There are a couple of related questions here; I'll take a stab at them.

First, it's actually remarkably easy to burn many metals under the right circumstances. A lot of metals are just waiting for a bit of activation energy so that they can oxidize. A nine-volt battery will easily and very rapidly heat a bit of wire from steel wool or a narrow strip of aluminum foil to incandescence and melting or oxidation. (Do be very careful if you try this one at home; small drops of molten metal are, obviously, dangerous.) Flash cubes contain lengths of very, very fine metal wire (typically some combination of the reactive metals magnesium and aluminum). When an electric current is supplied to the ends of the wire, it heats very rapidly due to its electrical resistance, to the point where the metal burns in a bright flash of light.

Conventional flash cubes, then, relied on a battery in the camera to supply that small spark of current that heated the wire in the cube to ignition. In the early 70s, battery-less flash cubes were introduced. Called Magicubes or X-Cubes, they relied on a piezoelectric crystal for their operation. When the flash was triggered, a tiny spring inside the flash was released mechanically; this spring drove a pin into a piezoelectric crystal, generating a pulse of current sufficient to ignite the flash. (It's very similar to the 'pushbutton' starters on modern gas barbecues.) These new contactless flash cubes were employed on cameras like the Kodak Pocket Instamatic 60; that linked web site has pictures of the cubes and an explanation of their function (scroll down).

I don't know of any flash cubes that were operated just by shorting the pins on the base of the cube; I agree with the original poster that such a setup seems unlikely to work (unless the flash cube contained an integral battery—something I've not heard of). The Magicubes had a mechanical trip (a little plunger extended up from the camera body into the cube to fire the flash) and lacked any electrical contacts. TenOfAllTrades(talk) 14:51, 9 September 2006 (UTC)

I've always wondered about that. I once bumped into someone in the dark (at a surprise party) causing a flash cube to fall to the floor and go off. Never knew how that was possible. Rmhermen 23:19, 9 September 2006 (UTC)

One could do it with some sort of capacitor, too. I have no clue if it ever was done that way, just that it could be done. Argyriou 16:52, 13 September 2006 (UTC)

clicking rat

Hi, I have a small albino rat, about 7 weeks old. She seems to be quite healthy (I think) aside from the fact that she exhibits a nearly continuous "clicking" sound. At first, I thought it mighth just be tooth-clicking, which I've read is a sign of contentment in rats, but nowadays she does it almost all the time, with a frequency of around 1 Hz. I'm no longer sure the sound is coming from her teeth - it almost seems like it's correlated with her breathing. She is taking some antibiotics for another issue earlier on that seems to have cleared up (she was sneezing a lot - but she doesn't any more). Any ideas? Feel free to forgo suggestions that I go and take her to the vet. I probably will anyways - just wondering if anyone has any advice or experience in the matter. Thanks! -bmk

I had a hamster probably 10 years ago that seemed to do the same thing, though not all the time. I assumed it was tooth-clicking.  freshofftheufoΓΛĿЌ  15:20, 9 September 2006 (UTC)

Perhaps he is developing a knack for echo location. A news story on TV showed a high school student who lost all eyesight at age 3 who navigates by making clicks with his mouth. He could detect a garbage can on the sidewalk in front of him, find a door, or detect where a person was by echolocation. He also skateboarded. Albino rats have poor vision in general, do they not? Rats are supposed to be able to hear sound frequencies far higher than we can, and the short wavelengths would provide better spacial resolution. A click generates a wide range of frequencies. Or maybe the rat has a sinus condition. Edison 05:12, 11 September 2006 (UTC)

LOL - I have heard that albino rats have poor vision, but I didn't think up such an imaginative (or optimistic) explanation. I hope that's the answer, but I suspect it was a respiratory thing, because it went away with a week long course of doxycyclin :) -bmk

SI unit

Why people created SI unit ??

In short, to standardize scientific calculations. For more information see International System of Units, especially the history section. - Dammit 14:50, 9 September 2006 (UTC)

Originally, during the French Revolution, a new, rational, system of measurement was created to unify measures in France. (France previously had many provincial systems.) Then it became popular for calculations. Peter Grey 01:17, 10 September 2006 (UTC)

It's much simpler. For a further elaboration, see my standardised answer on my user page. DirkvdM 08:10, 10 September 2006 (UTC)

Is it possible to see the change history of a definition

Is it possible to see the change history of a definition —Preceding unsigned comment added by 64.142.81.252 (talk • contribs)

What do you mean by 'definition' Do you mean the lede para?--Light current 17:52, 9 September 2006 (UTC)

Or do you mean etymology? If so, you need an etymological dictionary.--Shantavira 19:21, 9 September 2006 (UTC)

Or do you mean the history of a Wikipedia article? Just click the 'history' tab at the top. DirkvdM 08:33, 10 September 2006 (UTC)

This is a language question. What you're talking about is semantic change. A word's changing definition is generally only observable when it's documented. In comparative studies, it is possible to see a change in meaning of different morphemes. The English word black is cognate with the Russian word for white. AEuSoes1 08:38, 10 September 2006 (UTC)

Copper tubing

And other large bore metal tubing. How is it made?--Light current 17:51, 9 September 2006 (UTC)

Some are extruded... a slug of metal is pushed through a die, which forms it into a circular shape. To make a hollow pipe, the die is in the shape of a hole with approximately the outer diameter of the pipe, and the die has a solid center with approximately the inner diameter of the pipe. And yes, if you're wondering what holds the center of the die in place, it is connected to the outer part of the die via a 'fin' of sorts. The metal being extruded through the die splits to pass around that fin, then re-joins and cold-welds together, making a hollow tube. Have a look at the article on Extrusion. 192.168.1.1 20:24, 9 September 2006 (Huh?)

THanks. I was wondering about the central part. I have heard stories about 'floating' internal dies as well. Also its this rejoining that I dont understand. For instance how does it work. THere are'ent any seams visible on the finished pipes!. How come?--Light current 21:54, 9 September 2006 (UTC)

If enough pressure is put on metal, is will cold weld to other metal. See the link for an explanation. StuRat 00:25, 10 September 2006 (UTC)

Also, some large diameter thin tubing may be formed as a long, flat sheet, which is then bent to form a tube, and welded at the seam. This method can be used for heating ducts, for example (although many of those are rectangular). StuRat 00:25, 10 September 2006 (UTC)

Why would I want to heat ducks? Oh ducts! 8-). Sorry straight face 8-|--Light current 00:31, 10 September 2006 (UTC)

Some people do prefer a nice Cold Duck. :-) StuRat 03:21, 10 September 2006 (UTC)

I need to see how the m/c works really. Must visit a pipe factory.--Light current 00:40, 10 September 2006 (UTC)

If you do, make a schematic and add it to the extrusion article. I also have difficulty visualising this. DirkvdM 08:37, 10 September 2006 (UTC)

Many pipe extruders have a long spike that sticks through the extrusion orifice. The "other end" of the spike is attached somewhere in the manifold containind the metal, not too close to the orifice. The extruded metal can't occupy the space occupied by the spike and so the spike causes the void in the center. No seam. No cold welding. -- Fuzzyeric 01:07, 14 September 2006 (UTC)

West Nile Virus

is it a good strategy to infect myself with West Nile Virus now when I'm healthy and won't have anything more than a mild flu/cold from it? Then,I'll be immune FOREVERE! !! Jasbutal 20:31, 9 September 2006 (UTC)

Except for the part where you might die. No, it is not a good strategy. The best one would be to never contract West Nile fever. This way, you completely avoid the anorexia, nausea, vomiting, eye pain, headache, myalgia, diarrhea, rash, lymphadenopathy, and possibly, if it passes the blood-brain barrier, encephalitis, and spinal meningitis. Just not getting sick at all is the best "cure!" — [Mac Davis] (talk) (Desk|Help me improve)

what are you talking about!? No one between the ages of 20-60 years old dies of west nile unless they have a compromised immune system. The old and the young are the ones who die, with everyone else, you can barely even notice the symptoms. Jasbutal 20:55, 9 September 2006 (UTC)

The chances of you getting West Nile Virus are slim (depending on where you live), and I would take Mac Davis's advice and try not to get infected at all. And I don't think it's possible to get West Nile Virus on purpose...(?) —EdGl 00:08, 10 September 2006 (UTC)

There may be a low probability of dying from West Nile Disease if you are a healthy adult, but not a zero probability. So, it's a bad plan. StuRat 00:19, 10 September 2006 (UTC)

false. It's a bad plan if the probability of me dying later on in life from this virus doesn't outweigh the probability of me dying from it right now. Jasbutal 04:56, 10 September 2006 (UTC)

Ok, if you want to get into it further, you also have to assign a value to the intervening years, between dying now and when you are old with an impaired immune system. Also, there's a rather substantial probability that a cure will have been found before that happens. StuRat 09:54, 10 September 2006 (UTC)

Let's take an exaggerated example: you are currently 20 years old. If you voluntarily catch WNV now, you have a 40% chance of dying. If you don't, then you have a 50% chance of catching it involuntarily on your 60th birthday with a certainty of immediate death. Should you pass your 60th birthday, you will live until 80. What will you do? Of course, my figures are ridiculous, so feel free to come up with more accurate ones.-gadfium 05:56, 10 September 2006 (UTC)

Are you actually asking a question, or are you trying to educate RD?  freshofftheufoΓΛĿЌ  08:08, 10 September 2006 (UTC)

So I suppose the people who recommend against Jasbutal's vaccination idea also oppose the vaccination against small pox and other deadly diseases. After all, such vaccinations carry with them a small chance of dying. AEuSoes1 08:21, 10 September 2006 (UTC)

• You forget that the chance of dying from a vaccination is much lower than dying from the West Nile virus if you contract it. If I had to choose, I'd prefer the vaccin. - 87.209.70.231 14:12, 10 September 2006 (UTC)

heating my house

where can I find the prices of a btu of electricity vs a btu of natural gas (for whatever state)?

I want to do an analysis to see if it's cheaper to buy some space heaters and cut my gas service for this winter. Jasbutal 20:39, 9 September 2006 (UTC)

The prices vary from provider to provider, and since you don't seem to want to disclose a specific state, all we can do is estimate. Natural gas prices are certainly rising, and with the winter coming, heating costs are becoming more and more apparent. I'll do what I can to find some numbers for you, or maybe someone else might be able to answer first. --Russoc4 21:02, 9 September 2006 (UTC)

I should also add that forced air heaters and space heaters have different efficiencies when it comes to filling a house with heat. Space heaters are localized and are only intended for one room in use. Forced air heaters (usually) maintain the temperature in an entire house. --Russoc4 21:07, 9 September 2006 (UTC)

yea, I just wanted an approximation. I've got numbers now , just have to compute them: Jasbutal 21:12, 9 September 2006 (UTC)

http://www.eia.doe.gov/cneaf/electricity/epa/epat7p4.html

http://tonto.eia.doe.gov/dnav/ng/ng_sum_lsum_dcu_nus_m.htm

It's not worth it, by a big factor of 1.75 too. Jasbutal 21:21, 9 September 2006 (UTC)

electricity : $0.09/kwatthr = $0.09/(1000 J/s * 3600 s/hr * 1hr) = $2.5 * 10 ^ -8 per Joule

natural gas : $14.92/1000 ft^3 * 1 ft^3/1000 btu * 1Btu/1054.35J = $1.4 * 10 ^ -8 per Joule

Well, good job at figuring it out before us. Do try to refrain from using obscenities though. --Russoc4 21:26, 9 September 2006 (UTC)

sorry, I forgot this was the science desk Jasbutal 21:29, 9 September 2006 (UTC)

I am a bit confused about the 'obscenities,' as well as the somewhat seriousness of the comment. — [Mac Davis] (talk) (Desk|Help me improve)

it's a lot more casual over in Muskallaneous. Jasbutal 23:26, 9 September 2006 (UTC)

While it's quite true that it's more expensive to heat an entire home with electricity than with natural gas, there is another option: only heat the portion of the house you are actually using. Of course, you do need to heat the entire house enough to prevent the pipes from freezing, and I recommend using gas for this. However, if you only heat your bedroom to a comfortable temp at night, with an electric space heater, that should save you a fair amount of money. The daytime is trickier, as you're likely to move from room to room. However, you don't need to provide much heat to storage rooms. For most families, I'd think an automatic thermostat that turns the temp down to 40 at night, and up to 65 in the day, with supplemental heat from electric space heaters, might be the least expensive way to heat the home. The temp should also be turned down to 40 when everybody leaves the house for work or school. StuRat 00:00, 10 September 2006 (UTC)

There are also some safety issues with space heaters:

1) Don't ever use kerosene space heaters, they should be banned.

2) Don't let children use electric space heaters, as they can start a fire if paper is touched to the elements.

3) Get electric space heaters with tilt and overheat sensors, which turn off under those conditions.

4) Don't ever use a space heater with a frayed cord or a cord that overheats.

5) Don't ever run the cord under carpet, as that will allow heat to build up.

6) Make sure any extension cords are rated to handle the space heater's wattage (typically 1500 watts).

7) Place space heaters far from any flammable materials, like blankets.

StuRat 00:12, 10 September 2006 (UTC)

...and wear a hat. But coming back to the original question, the price per unit of energy should be shown on your utility bills. In the UK it has to be there by law.--Shantavira 08:19, 10 September 2006 (UTC)

Rats wanting to be held

According to the article Pet rat, pet rats often (or, at least sometimes) position themselves near the cage doors, wanting to be held by their human owners. Is there really any scientific proof for this? Is it likely that rats actually want to be held? Could there not be another reason for their behaviour (e.g. wanting to escape)? The article also says that some rats enjoy riding through the house sitting on their owner's shoulder. Is this idea proven? Perhaps the rats position themselves on the shoulders, merely being too afraid climbing on the sweater? In general, common belief and this article says (assumes?) that rats enjoy (human) social interaction: my general question, thus, is if this really is true, or if it is merely a human wish. --Andreas Rejbrand 21:10, 9 September 2006 (UTC)

The phrase is "wanting to be held", not "wanting to be hold". StuRat 23:42, 9 September 2006 (UTC)

• I suspect you haven't spent any time with rats. They are very affectionate, they distinguish between different people, they seek out pleasure (like high viewpoints giving them free rides). Now, obviously, one cannot scientifically prove they "want" anything, since rat-mind-readers aren't any more available than human ones are, but they certainly express what appear to be preferences. --jpgordon^∇∆∇∆ 21:31, 9 September 2006 (UTC)

Well, actually, I have spent quite some with pet rats (http://english.rejbrand.se/rejbrand/djur.asp). But yet I cannot say I am sure about the hypotheses. --Andreas Rejbrand 22:12, 9 September 2006 (UTC)

It is near impossible to "prove" anything about animal behaviour. You could ask, how do we know dogs actually enjoy human interaction? How do we know that them retreiving a ball or a frisbee is enjoyable, and that there is not another reason for their behaviour? The answer is that, when given an opportunity, behaviour without an obvious inherent biological purpose that animals freely choose to do is what we define as behaviour they "enjoy", based on the premise that that is what humans do. Whether there is another function for such behaviour is open to interpretation, in the same way human behaviour is. Consider why people go to the gym, play sport, or even have sex for enjoyment. The answer is: because our body rewards our brain with positive inputs in reponse to these activities. And this is because it makes evolutionary sense to reward and encourage behaviour that is constructive to survival and discourage behaviour that isn't. So if you take "enjoyment" in that context, it is clear rats do enjoy human interaction, but the reason for that is open to speculation. Rockpocket 22:32, 9 September 2006 (UTC)

Wanting to be held is a mammalian/bird thing, as the young of pretty much every species desire contact. Many "pet" mammals and birds retain this characteristic into adulthood. While this is mainly true of social species, some not-social species, like cats, also retain this characteristic. StuRat 23:47, 9 September 2006 (UTC)

Do you ever sit at your cage door, wanting to be held? (Someone had to ask.) DirkvdM 08:44, 10 September 2006 (UTC)

In my case, I really am just trying to escape. :-) StuRat 09:49, 10 September 2006 (UTC)

Similar questions could be asked about humans. Do they really want to go throught the same routine everyday (even every holiday for some)? Or do they just not know any better? DirkvdM 08:44, 10 September 2006 (UTC)

Let me rephrase my question slightly: does a rat sitting on a shoulder feel pleasure (as the article claims) or fear (e.g. of falling down)? Does a rat sitting near the cage door want to be held by a human, or does it want to escape? --Andreas Rejbrand 10:54, 10 September 2006 (UTC)

My reason for asking is merely that I want the best for my rats, combined with a bit of scientific interest. --Andreas Rejbrand 10:55, 10 September 2006 (UTC)

What they want might not be what's best for them. Suppose they want to escape. Would they be able to survive? They might have to compete with other (wild) rats and domesticated rats wouldn't stand a chance. If you want what is best for domesticated rats maybe you should not have bought them (if that's what you did), thus creating a demand for the breeding of more domesticated rats. Assuming they don't want to be kept in captivity, that is. But maybe they don't mind at all, if they don't know otherwise. That is actually quite probable. There is still the natural drive that all animals have. Look at how wild rats live and try to create circumstances that gives your rats an opportunity to live such a life. DirkvdM 13:33, 10 September 2006 (UTC)

True, indeed. Yet my original question has not been answered. In fact, I believe no human really know the answer. But the authors of the Fancy rat page must have learned these "facts" somewhere. --Andreas Rejbrand 16:27, 10 September 2006 (UTC)

I refer you to my answer above, it depends on how you define "pleasure". Most definitions are subjective in terms of animal behaviour ("gratification", "satisfation", "enjoyment") However, one definition is "one's will, desire, or choice". If the rats freely choose to ride on your shoulder - it is their choice - then we could say they make "make known their pleasure". Strictly we should no use terms such as these in describing animals, its a type of anthropomorphism. However, if we take our definitions of enjoyment/pleasure as i described above, then its not so innapropriate. Rockpocket 20:22, 10 September 2006 (UTC)

LED usage

Why did it take so long for LEDs to be used in traffic lights, road signs and for vehicle lights?--Light current 22:39, 9 September 2006 (UTC)

There must have been some change in the technology, as they now seem to be much brighter than they originally were. StuRat 23:30, 9 September 2006 (UTC)

Hi briteness LEDs have been available for some time (>10yrs) but its only recently I ve started seeing them used in these apps. Could it be to do with the cost?--Light current 00:08, 10 September 2006 (UTC)

Yes. Until recently, LED's in the specific colors required for traffic signals were extremely expensive. Both the reduction in manufacturing cost, and also the increase in utility (electric) costs have made LED signal faces very cost effective. Early LED's did not have the proper yellow and green colors to conform to the ITE standards. Also, a typical incandescent traffic light bulb is 160 watts. An LED face draws from 10 to 25 watts, making the return on investment much better. 192.168.1.1 01:01 10 September 2006 (UTC)

Whats ITE?--Light current 05:24, 10 September 2006 (UTC)

Suppose (a very rough estimate) that on average every 100 household neighbourhood has one intersection with 10 lights (four or more for the cars, same for pedestians and possbly some for cyclists). Suppose a saving of 100 W per light. That's 10 W per household. 24/7. A typical lightbulb comsumes 50W, about 20% of the time (at night). So it is an energy saving equivalent to one less lightbulb per house. Nothing big, but not bad either. DirkvdM 09:01, 10 September 2006 (UTC)

Lightcurrent: Sorry, I should have put that in. ITE = Institute of Transportation Engineers. www.ite.org

DirkvdM: Actually for the agency paying the bills, it is a huge savings. Given a typical intersection with three vehicle heads on each mast arm, for a total of 12 heads, and eight more pedestrian heads, there will always be 20 faces lit at any time. Traffic signals operate 24 hours a day. The energy savings is a pretty big deal, 160W x 20 versus 15W x 20. We're paying around ten cents per KWHour (if I recall correctly), and we've just slashed our operating cost to around a tenth of what it was with incandescent bulbs. Then there's the labor savings. Incandescent bulbs were regularly replaced in a formal re-lamping program. The LED faces will last for up to ten years without requiring re-lamping at all. My agency operates around eighty signals, so for us the decision to upgrade to LED's makes economic sense. --192.168.1.1 17:23 11 September 2006 (UTC)

Ah yes, any labour savings usually make a huge impact. But for the electricity cost my story wasn't all that different, except that I approached it from a differnt angle, not the total cost (for what area?) but the cost per household, which scales better (just multiplky by the numebr of households). Also you're talking about much bigger intersections, of which there aren't that many. So they sound inpressive but the more ubiquitous smaller intersections make a bigger diiference. That is a common mistake, to focus on the big things, but life consists more of the l;ittel things. Take the New York WTC attack. That made people fear terrorism, because thousands died. But because it was pretty much a one-off thing it's peanuts. Cars kill as many people in the US every few months. Every few months. And that's just the US. Worldwide the deathtoll is about half a million people per year. That is what people should fear, not terrorism. A common mistake, but a costly one. DirkvdM 17:34, 10 September 2006 (UTC)

The simplest intersection with pedestrian lights will have to have 8 of those plus 4 light for traffic so 12 lights total. (more than Dirk's 10, less than 192.'s 20.) But I don't think we can assume that intersections of two two-lane roads with traffic lights are the most common kind of lighted intersection as multi-lane roads are much more likely to have traffic lights. Rmhermen 03:21, 11 September 2006 (UTC)

First off, I should mention that I was reasoning from an Amsterdam perspective. For a city like Eindhoven, that is built for cars, it will be different. But in most places, the bigger the roads, the fewer there will be of them, so I suppose the calculation will be different but the outcome roughly the same. DirkvdM 08:15, 11 September 2006 (UTC)

Eye burns

How quickly do frostbite/heat burns dissipate when on the eye? Can you lose parts of it if you aren't careful? — [Mac Davis] (talk) (Desk|Help me improve)

Can you get frostbite in the eyes? maybe, if you splash cryogenic liquid in. [3]--Light current 00:42, 10 September 2006 (UTC)

In Antarctica, as well as other places, it is so cold and dry I bet you can. I was thinking of LN2 actually. — [Mac Davis] (talk) (Desk|Help me improve)

I dont remember hearing of any of the Antarctic explorers getting frostbite in the eyes. Other parts of the body - yes. THe simple answer is to wear protective goggles when you pour it.--Light current 01:22, 10 September 2006 (UTC)

The skin around the eyes can certainly get frostbitten, but under extremely cold conditions your eyes will water profusely as a way (I must assume) to keep them from getting too cold and freezing over.  freshofftheufoΓΛĿЌ  08:03, 10 September 2006 (UTC)

The brain is always maintained at operating temperature, irrespective of how cold it is, because else you'd die. Maybe the eyes are so importatnt that they get the same treatment. Just a guess. DirkvdM 09:11, 10 September 2006 (UTC)

I suppose you could get a frostbitten eye by pouring liquid nitrogen on one. My suggestion: don't do that. Similar comment for putting a cigarette out in your eye, I suggest an ashtray, instead. StuRat 09:44, 10 September 2006 (UTC)

I must admit that what you say does sometimes make a lot of sense. DirkvdM 13:35, 10 September 2006 (UTC)

Though, I don't think real frostbite would actually occur with LN, because that takes time, and it is usually the result of the body slowly removing all blood from the region under extreme cold. You'd probably just freeze your eyes momentarily, and then they'd get all swollen and nasty.  freshofftheufoΓΛĿЌ  09:37, 11 September 2006 (UTC)

EMP's

why should I be worried about http://en.wikipedia.org/wiki/Electromagnetic_pulse ??

My PC is in a faraday cage, as is almost all important electronic equipment. right? Jasbutal 23:25, 9 September 2006 (UTC)

Well, an EMP could signify that a nuclear device has been detonated in the area, news of which... would probably worry me, I don't know about you though... --Mnemeson 23:29, 9 September 2006 (UTC)

You really don't need to worry about it, who told you that? — [Mac Davis] (talk) (Desk|Help me improve)

What about the wires into your PC-- are they filtered well enough to stand EMP?--Light current 00:09, 10 September 2006 (UTC)

you do all realize that if you bank with a modern corporation, your account is just a file on a computer...right? I'm not worried about money, or people, or nukes, or whatever, i'm worried about my dang money. Jasbutal 04:54, 10 September 2006 (UTC)

A communist's wet dream, an idea used in several films - wipe all banks clean and mankind will start with a clean slate. Any new money will have to be distributed evenly if there is no way anyone can prove how much money they had. I wonder if the same principle applies to companies and even nations. Of course rich countries have more and better production facilities and other physical goodies, so they can easily assume the top dog position again, but any differences in virtual property (money) will have disappeared. Right? Also, suppose not just money, but proof of ownership of a factory is deleted? Would that be possible and how migh ownership be distributed then? DirkvdM 09:19, 10 September 2006 (UTC)

you're scaring me dirk!! What can be done about the EMP threat!? back up everything on notarized papers? Jasbutal 18:25, 10 September 2006 (UTC)

That actually happened in the Soviet Union back in the 70s, I think it was. They massively revalued the ruble and introduced a new series of banknotes. People had to line up to exchange the old ones for the new ones, but they had to be able to explain how they had come by the old ones legitimately, otherwise they couldn't get the new ones, and the old ones became useless after a short while. Tough titties for a lot of people. JackofOz 21:04, 10 September 2006 (UTC)

Same in the EU with the introduction of the euro. If you wanted to exchange more than a certain amount of money (around the equivalent of 5.000 euro, I believe) you had to 'source it', so to say. A big blow to the bigger black marketeers. DirkvdM 08:18, 11 September 2006 (UTC)

banks will have there records backuped at multipe seccure sites round the country, and big banks have proberly gots lots of precautions for any problem including emp strikes--Colsmeghead 21:18, 14 September 2006 (UTC)