Wikipedia:Reference desk/Archives/Science/2007 October 21

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October 21

bamboo

Does the earth/soil that Bamboo grows in become depleted to the point that would classify it as non-sustainable? —Preceding unsigned comment added by 76.79.66.37 (talk) 00:09, 21 October 2007 (UTC)

It looks like translation from Dutch is taking place at our Crop rotation article. I don't see Bamboo on the list. However, either of those links might help you.--Mdwyer 05:52, 21 October 2007 (UTC)

Bamboo is essentially no different from any other crop. If it is being harvested, then the soil will eventually become depleted. If it is growing wild, or for decoration, it can sustain itself for many generations because the nutrients are being recycled.--Shantavira|^{feed me} 12:02, 21 October 2007 (UTC)

Female cats

Please respond from a past experience if you've had a similar situation to deal with. We have a female cat that is mostly indoors and plays by herself. She avoids wild cats and we keep her away from the occasional male cat. Could there be a cordial relationship between her and a female wild cat? —Preceding unsigned comment added by 61.17.221.186 (talk) 05:31, 21 October 2007 (UTC)

Just to clarify - are you asking us if we think that your cat is a lesbian? --Kurt Shaped Box 05:38, 21 October 2007 (UTC)

Wild cats are solitary creatures. Domestic cats are territorial and they don't welcome other cats unless they are brought up together. You will find more information at Cat#Cohabitation.--Shantavira|^{feed me} 09:34, 21 October 2007 (UTC)--Shantavira|^{feed me} 09:34, 21 October 2007 (UTC)

Do you mean "wild cat" as in feral cat or really a wildcat? I think it will differ quite a bit if you are talking about domesticated-but-feral or totally undomesticated cats. --24.147.86.187 14:48, 21 October 2007 (UTC)

I have to disagree (slightly) with Shantavira. Domestic cats (pet or feral) are social to some degree as studies of colonies of feral cats have shown. It is true that those cats which grow up together are the most likely to become buddies. However, it is possible to introduce adult cats to each other such that they become friendly or at least tolerate each other. Thus it is possible that a wild (feral) female cat could become friends with a female pet domestic cat. It depends on their individual personalities and the circumstances of their introduction.--Eriastrum 19:00, 21 October 2007 (UTC)

• You might also be interested in the Wikipedia article Homosexuality in animals. There's no info on cats, but the article does report on positive accounts of homosexuality among lions. --M@rēino —Preceding comment was added at 18:17, 22 October 2007 (UTC)

diffraction image

1. Can a diffraction grating make an image of a monochromatic light source?

2. (see Wikipedia:Reference_desk/Science#DVD-R Strange optical effect )When using a DVD-R to look at a poly-monochromatic light source the reflected image is many (~5) times bigger than the images I assume to be due to diffraction. Why is this?87.102.16.28 11:47, 21 October 2007 (UTC)

Plant question

Could somebody please tell me what plant species this is?: http://en.wikipedia.org/wiki/Image:Plantbathroom1.JPG http://en.wikipedia.org/wiki/Image:Plantbathroom2.JPG and if it would have been around in the Mesozoic era, and if it would have existed even before and survived the Permian–Triassic extinction event? Thank you. (PS: I seemed to have made a mess of uploading photos, sorry! am not sure exactly how to do this, if anyone can correct, please do, thanks.)--AlexSuricata 15:59, 21 October 2007 (UTC)

It looks like an asparagus fern. Ferns have been around a long time. According to Geologic time scale, they arose in the late Carboniferous, before the Permian. Whether that species was around then, I don't know. By the way, wait for the steam from your shower to dissipate before you try to take pictures in your bathroom, OK? --Milkbreath 16:16, 21 October 2007 (UTC)

It's not steam, it's the 1/2-second exposure time. You can't take exposures that long without a tripod, or at least resting the camera on something. The Olympus FE-120 has a built-in flash, right? You should use it. —Keenan Pepper 18:39, 21 October 2007 (UTC)

I agree with Milkbreath that the plant is probably "Asparagus Fern", however, it is not a fern. Despite its common name it is a much more modern flowering plant related to lilies. It used to be Asparagus plumosus, but the genus Asparagus has recently been split. The current botanical name for Asparagus Fern is Protasparagus plumosus.--Eriastrum 18:51, 21 October 2007 (UTC)

The asparagus fern would not have been around in the Mesozoic, so only its ancestors survived. Graeme Bartlett 01:10, 22 October 2007 (UTC)

Personally I'm somewhat doubtful that any species living today was around in the Mesozoic era. While some animals and plants have survived relatively unchanged for a long time, it doesn't mean that they are completely unchanged or are the same species. You might want to read living fossil Nil Einne 07:10, 22 October 2007 (UTC)

Why the electricity transmission voltage is generally multiples of 11?

I have thought of this question for a long time, but haven't got a satisfactory answer anywhere. Why is the AC electricity supply voltage always in multiples of 11. For example, in US/European countries, it is 110V; in some Asian countries, it is 220V. The high voltage supply lines are generally 110kV, 220kV, 66kV etc. In general, if you observe the AC transmission voltage, it will be in multiples of 11. —Preceding unsigned comment added by Kanwar rajan (talk • contribs) 16:05, 21 October 2007 (UTC)

This question has been asked here at least 3 times before - see Wikipedia:Reference desk archive/Miscellaneous/November 2005#Electricity voltage, Wikipedia:Reference desk/Archives/Science/2006 December 6#value of voltage in power supply and Wikipedia:Reference desk archive/Science/May 2006 part 2#High voltage power supplies for the answers. Laïka 16:16, 21 October 2007 (UTC)

Added those to Wikipedia:Reference desk/FAQ. Note that it's only 110V in the US. The EU had 220 and 240 V and standardised to 230V. DirkvdM 17:52, 21 October 2007 (UTC)

It's not even 110 volts in the US; it's usually 117 VAC ± some amount and we commonly refer to it as "120". Today, at my house and according to two different DVMs of unknown callibration, the mains power is reading 121.4 and 121.7. 'Guess the power company is in cahoots with the light bulb company, ehh?

Atlant 18:57, 21 October 2007 (UTC)

...especially the "long life" bulbs you can buy at Wal-Mart and manufactured by GE. More like 30 to 300 hours instead of the 1300 sold as. 71.100.9.205 19:19, 21 October 2007 (UTC)

Leaky coax antenna and Cable

I had a question regarding a previous post where it stated that someone had a college radio station that used leaky coax cable and it was limited to just the buildings. Did the buildings have to have leaky coax or any other cable put into the buildings to make this work? —Preceding unsigned comment added by 67.127.97.65 (talk) 16:19, 21 October 2007 (UTC)

As I recall, it was simply laid onto the roofs of the buildings. But it was a long time ago! We were broadcasting on 998kHz/300m AM....oh - but wait - this is Wikipedia.! There is an article about it: UKC Radio...Wow!SteveBaker 18:01, 21 October 2007 (UTC)

So, in order to get the coax antenna to work, if first must have coax cable laid out around this center you want to get reception in, is that correct? —Preceding unsigned comment added by 68.120.228.255 (talk) 01:07, 22 October 2007 (UTC)

and also in the interior of the space that you want to cover, if its a large area. From Steve's experience the signal only travels a dozen or so meters from the cable. You should be able to cover a cave, pipe or tunnel with one run of coax. Graeme Bartlett 01:14, 22 October 2007 (UTC)

Would it not work if it were from one antenna to another antenna if both are leaky coax antennas? —Preceding unsigned comment added by 67.122.136.43 (talk) 19:36, 22 October 2007 (UTC)

Green bins and gulls

Hi. I've been wondering, if a town or municipality adopted the green bin policy, where compostable trash goes to farmers' fields instead of landfills and garbage cans, what would happen to all the gulls who partially epend on the trash for food, as well as the other animals who depend on it partially (eg. rats, mice, ants, raccoons, foxes, etc)? Would they die off, or have to find other sources of food? For example, I know the gull population around most school properties are quite dense. My main question is, if the green bins decreased the amount of food garbage in garbage cans, landfills, etc, would the gull population increase or decrease in density around schools and parks? I know racoons can often poke around in garbage cans, but putting all the food scraps in the green bin, which can often be closed with a latch, might solve the problem. Similarily, would the raccoon population increase or decrease in areas such as schools where there is often a lot of litter, or would they have to move out of cities and towns which have adopted this policy where there is not enough food? What about rats and otehr animals? Where would each animal gather the most in population density across the municipality? Also, where do the squirrels get all those peanuts an acorns? Thanks. ~AH1^(TCU) 16:30, 21 October 2007 (UTC)

In our area you can find very well fed raccoons, foxes, rats, mice and ants living on nothing more than left over dog and cat food. Any place people eat outdoors is another great source like bus stops, employee lunch tables (or the employee/customer bicycle rack which some employees and customers prefer). 71.100.9.205 19:22, 21 October 2007 (UTC)

The gulls would probably just move on somewhere else where food was more readily available. There's a landfill a few miles from my house that's in the process of being sealed. Apparently, the number of gulls at the next landfill along (30 miles or so) has almost doubled. I hypothesized that my town was going to be overrun with flocks of aggressive, starving gulls once they started covering up the refuse with plastic and earth but so far, it doesn't seem to have happened like that at all. The usual 'town gulls' are still here, of course - continuing to do what they do (how sad is it that I can now recognize individual gulls by location of favourite perch, plumage variations and scars/old injuries/deformities?). I guess that there must've been two separate flocks with different habits all along. --Kurt Shaped Box 19:49, 21 October 2007 (UTC)

artifiial eye Interface

If I wanted to interface an electronic circuit such as a CCD array to the human ocular nervous system what kind of interface would I need? I know that I would probably have say like a surface with "hair" on the back of the CCD chip that sent out nerve pulses individually for each pixel and where nerves could attach but then would I have to use genetic engineering to get the nerves to attach to each "hair" and even still what material would I use to make the "hairs" so that the genetically engineered nerves would attach and stay attached like the granular surface of metal joint replacement? (...or will Mother Nature throw me to the ground and squat on me for thinking these thoughts?) Clem 19:37, 21 October 2007 (UTC)

It has been somewhat done with varying degrees of success. See Visual prosthetic, although it doesn't give many technical details. --Bennybp 22:26, 21 October 2007 (UTC)

Why would you need genetic engineering? The 'hairs' would have to send out the same signals that whatever you're replacing (the retina, I assume) normally send out, and the nerves should connect. Afaik. I'm no expert in this field. That is, assuming those nerves regenerate. Is that what you were referring to? DirkvdM 07:27, 22 October 2007 (UTC)

I'm assuming that if a nerve ending is disconnected from a receptor that it might regenerate and reconnect... but not to an artificial ocular nerve ending unless the disconnected nerve was somehow genetically reengineered to cause or to allow it to reconnect to the artificial "hair" nerve ending instead, or as well. Clem 10:39, 22 October 2007 (UTC)

I don't know much about genetic engineering, but can you do that in already existing living tissue, and on that location? Anyway, genetic engineering seems a lot more difficult than mechanical engineering of the 'hairs'. Or maybe a layer of living tissue could be attached to the artificial eye interface before implantation. And amybe that might be genetically engineered, so you get your way after all. :) DirkvdM 17:22, 22 October 2007 (UTC)

It's not a matter of genetics. You really can't replicate the precise interface between eye and brain - it's too complicated, too weird (compared to a CCD camera array at least) - and may even be wildly different between any two individuals. You'd have to connect it up any old how to the nerve endings and rely on the brain to re-learn how to see using the new device. Part of the problem though is that the eye doesn't send "pixels" to the brain - it sends higher level concepts like "there is a 32 degree diagonal light/dark transition moving left-to-right at 10 degrees of arc per second". Since our electronics won't be doing that, the brain proper has to do work that would normally be done by the layers of neurons on the back of the retina. So it's unlikely that your eyesight would ever be as good as a real human eyeball. But having said that, people have managed to "see" with something as crude as a grid of a few thousand little pins strapped to the back of their hand - one pin for each pixel. It's amazing how the brain can learn that stuff. SteveBaker 20:27, 22 October 2007 (UTC)

Wow, do you have a link for that? I'd really be interested to learn more about that.

But it depends on what exactly you are replacing. If it's just the retina, then the interpretation done by the eye will remain intact. DirkvdM 06:34, 23 October 2007 (UTC)

geomagnetism

these r some terms "1.magnetic poles,2.geomagnetic poles,3.geographical poles,4.physical poles,"and i m finding my self nowhere among them.do some tell me wat is the basic differences in them in easy words?Roar2lion 20:56, 21 October 2007 (UTC)

Wikipedia has Geographical pole, Magnetic pole, North Magnetic Pole, South Magnetic Pole. --JWSchmidt 21:04, 21 October 2007 (UTC)

Geomagnetic Pole redirects to magnetic pole, which suggests they mean the same. But I suppose 'geomagnetic' refers to Earth, not the poles of other astronomical bodies, so the redirect isn't entirely correct. I changed the page to reflect this. Not sure about the layout, but at least it's clearer now. DirkvdM 07:47, 22 October 2007 (UTC)

On second thought, doesn't 'North Magnetic Pole' refer to one pole of other astronomical bodies too? DirkvdM 08:05, 22 October 2007 (UTC)

The 'geo' prefix in geomagnetic pole is just to distinguish it from other magnetic poles which do not happen to be associated with planetary bodies. Eldereft 20:35, 23 October 2007 (UTC)

The Greek word geo means 'Earth'. And afaik, the prefix is always used in that sense. DirkvdM 09:05, 24 October 2007 (UTC)

We have the (geo)magnetic poles (where a compass points), the rotational axis of the earth and the axis about which that first rotational axis precesses over a period of 25,800 years. (The gyroscope animation in the precession article shows the difference between the last two rather nicely.) There are also the two points on the surface of the earth that mankind has arbitarily decided to label 90 degrees of latitude north and 90 degrees of latitude south. Which ones have which names though? SteveBaker 15:02, 22 October 2007 (UTC)

The rotational axis of the Earth gives the physical/geographic poles, which are at ± 90°; Santa Claus lives at +90°. Precession of the equinoxes has no particular cartographical significance, though it does mean that your astrological sign is wrong. Eldereft 20:35, 23 October 2007 (UTC)

Cold beverages?

Why do people prefer to drink most beverages cold, even if not in a very hot environment? Is there any kind of physiological basis to this preference? Thank you very much for your time!

24.88.103.234Timothy —Preceding comment was added at 22:25, 21 October 2007 (UTC)

I would suggest that since most drinking water is not heated, the ability to drink hot liquids would not have much of an evolutionary advantage, except for geologically active regions with hot springs. Confusing Manifestation 22:32, 21 October 2007 (UTC)

You've never been to Europe and been served room-temperature beer, have you? Americans have the biggest craze for cold beverages in my experience. Delmlsfan 22:37, 21 October 2007 (UTC)

Because they're delicious? --ffroth 23:32, 21 October 2007 (UTC)

The coldness induces an almost numbing effect to the mouth. Acceptable 00:12, 22 October 2007 (UTC)

That explains abominations like Bud Light and XXXX, for sure ;-) --Stephan Schulz 00:18, 22 October 2007 (UTC)

Aussies like their beer even colder. And they have special stubby holders (no article? Jack, here lies a task for you) to make sure it stays cold (google images). However, drinking cold drinks doesn't really cool you down. It cools you down inside, but your torso needs to stay a constant temperature. So your body starts generating heat to get the torso back to the right temperature. So you actually heat up. So what I did in the land of Oz was take the beer out of its stubby holder and use it to cool my wrists, which did cool me down. After a while, when the beer had warmed up enough, I drank it. The Aussies declared me nuts. And right they were, just not in this case. :) DirkvdM 08:04, 22 October 2007 (UTC)

Around here(CA/USA) they are called Can/Bottle Cozies... and I thought there was an article for them somewhere near that name, but be damned if I can find it. Dureo 11:50, 22 October 2007 (UTC)

I've seen it spelled 'Koozie' (which gets you a bazillion ghits for companies that sell customised koozies/cozies) - but I can't find an article with that name either. It's getting hard to find common household items that don't have articles about them so I can't help feeling we're just not looking in the right place. If someone does find an article, let's #REDIRECT the heck out of it! SteveBaker 14:50, 22 October 2007 (UTC)

Ah, my link now redirects to drink cozy - both the article and the redirect have been created by TotoBaggins today, it appears. Probably a passer-by here. Btw, we now have a stub on the stubby holder. I suggest we leave it like that (hold that stub). :) DirkvdM 17:33, 22 October 2007 (UTC)

Mountain Laurels

Is Texas mountain laurel the same sort of plant as the "mountain laurel" with white flowers in North Carolina? —Preceding unsigned comment added by Vultur (talk • contribs) 23:48, 21 October 2007 (UTC)

Welcome to Wikipedia. Try searching for "Mountain Laurel" in the Search box to the left. You'll find it will immediately bring you to the article for Kalmia latifolia (the latin name for Mountain Laurel). You'll notice that at the top of the page, there's a link to the Texas Mountain Laurel article, Texas Mescalbean. You can see from the articles that the two plants come from different Order and Families, so they are definitely two distinct plants. -- JSBillings 13:21, 22 October 2007 (UTC)