Wikipedia:Reference desk/Archives/Science/2006 September 7

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September 7

Value of chemical elements

I noticed that the value of germanium in 1997 and 2000 was provided in that article. That sparked the question: what is the best source for determining the current value of such commodities? Is there a reliable web source for finding this information. Much thanks in advance. I'd like to find a consistent source for updating this aspect of the chemical articles. LeyteWolfer 05:57, 7 September 2006 (UTC)

'Spot' markets/commodity markets deal with commonly traded elements. There is data available on rare elements, I saw it recently (osmium data I think, and from a US govt source (less certain abt this)), but I can't remember where. That doesn't help at all, does it? Rentwa 06:53, 7 September 2006 (UTC)

No, I'm afraid not, but thanks for trying. LeyteWolfer 22:22, 7 September 2006 (UTC)

The USGS Mineral Commodities Summaries, here [1] generally include average prices for the years of the reports. Geologyguy 20:05, 8 September 2006 (UTC)

Geologyguy, you, my friend, are a god amongst men. Thanks a lot. LeyteWolfer 18:22, 9 September 2006 (UTC)

Weight versus elevation.

As you go farther from the center of the Earth, your weight decreases due to a weaker acceleration. How much does your weight alter from the Earth from an increase or decrease in elevation? Say I move from a place of lower elevation to a place of an increase in 500 feet of elevation. About how many pounds theoretically did I lose in weight? -User:NealIRC 7 September 2006 2:05 (UT)

Try staring at Newton's inverse-square force law, and think about the radius of the Earth. Melchoir 02:00, 7 September 2006 (UTC)

It's more complex than one would think, since you can't view the mass of the Earth as a point mass at the center until you are tens of thousands of miles into space. Instead, the mass of each atom, whether solid, liquid (water), or gas (air), must be considered, along with your distance from each atom. I've heard that the force of gravity actually increases slightly when you gain a little bit of altitude, due to the added mass of air below you pulling you down and the reduced mass of air above you pulling you up. StuRat 02:28, 7 September 2006 (UTC)

If we can approximate the physical earth as a nested collection of spherically symmetrical homogeneous shells, then the point mass simplification is fully equivalent for Newtonian physics as long as you stay on the outside. --Lambiam^Talk 02:53, 7 September 2006 (UTC)

Melchior and Lambian are right. It's easy to calculate. Clarityfiend 04:05, 7 September 2006 (UTC)

No, because the atmosphere does count. While it's mass is far less, it is far closer, if you are, say 1 km off the ground, so still has a rather significant effect on the net gravitational effect. Only after you are completely outside the atmosphere would such as approximation become accurate. The density of the Earth is also far from constant, which makes the point-mass model less accurate. See shell theorem for more detail. StuRat 04:20, 7 September 2006 (UTC)

Actually, as long as the density profile is spherically symmetric, the point-mass model is still good. As for the atmosphere... anyone want to crunch numbers on the two competing effects? Melchoir 04:25, 7 September 2006 (UTC)

The atmosphere has no significant effect, since the gravitational force falls off as r squared. There just isn't enough mass close enough to do much. Also, the non-symmetric density of the Earth doesn't really affect things either. The fact is there is a point where, if all the mass of the Earth were concentrated there, you would feel the same gravitational pull. For purposes of the original question, that's good enough. The non-homogeneity might move it a few miles one way or another (the oblate spheroid shape of the Earth too), but who cares? Compared to the distance between the point and the surface, it's negligible. Unless you're looking for ultra-accuracy, Newton's equation will give you a pretty good answer.

Here's a few rough numbers for the effect of the atmosphere (using ballpark figures, but they will give a very loose upper limit). At 120 km up, according to the wikipedia article, an astronaut notices the atmosphere upon reentry, so let's use that. The density of air at sea level is 1.2 kg/m cubed (sorry, don't know how to do superscripts). So a half sphere surrounding our intrepid questioner would mass about 10 to the 15th kg if the density didn't drop off as you go up; for simplicity, I'm going to use that figure. I don't want to go through and have to integrate that, so let's use an average distance of say 1 km. Crunch the numbers and you get about 0.07 Newtons. That's making the terrible assumption that the gravitational force is all in one direction, which it isn't. Even with all the simplifications grossly inflating the force, that's really, really miniscule.

Finally, you'd get a 1% decrease in weight when you are about 30 km further up (roughly - I only have the Windows calculator to work with). Clarityfiend 05:02, 7 September 2006 (UTC)

Again assuming spherical symmetry, the atmosphere does not contribute to the gravitational acceleration experienced by a body on the surface. In general, for a body at distance R from the centre, only the part within a sphere of radius R around the centre contributes to the net gravitational effect. --Lambiam^Talk 09:48, 7 September 2006 (UTC)

On the other hand, whether you are close to the equator or near the poles makes a more important difference in your weight because of the centrifugal force. A quick calculation yields that if you are at latitude φ, the g acceleration you actually feel is reduced by approximately 8.544*10^-4 m s^-2 * cos² φ. This means that if you travel from the poles to the equator, your weight will change by, say, 7 grams. If you travel only within the country it can barely be more than one or two grams. That's however still comparable to the difference you get from the altitude difference above. – b_jonas 08:43, 7 September 2006 (UTC)

The gravitational force is inversely related to the distance squared. So if the distance doubles, the gravitational force is reduced to 1/4. More in general, you should divide the two distances. Assuming Earth can be treated as a point mass at the centre of the actual Earth (so at a distance of about 6000 km), then if you go up 1 km, the distance increases by 6001/6000 = 1,00016666, so the gravitational force decreases to (6000/6001)² = 0,999666 of what it was. Earth's gravity says "an increase in altitude from sea level to the top of Mount Everest (8,850 metres) causes a weight decrease of about 0.28%". Let's do the math again, this time with the more accurate radius of 6372,8 km. (6372,8/(6372,8+8,85))² = 0,997228346. That's a decrease of about 0,0028. Or 28%. So either we're both right or we're both wrong or this is some weird coincidence. :) So if you weigh 100 kg (which I hope not), your weight will decrease by 280 grams when standing on top of mount Everest. That's about the weight of a meal.

500 feet is about 150 m, so that would then be something like a few grammes of weight 'loss'. You do the math. DirkvdM 09:14, 7 September 2006 (UTC)

That's not a meal for a 100 kg person, more like an appetizer. :-) StuRat 09:18, 7 September 2006 (UTC)

Well, Acceleration due to gravity suggests a number of corrections: latitude-dependent centrifugal force (0.03 m/s^2), equatorial bulge (0.02 m/s^2), free air correction (3*10^-6 1/s^2 (i.e. m/s^2 per meter of elevation), Bouger correction (additional attraction due to a local slab of ground above sea level) (1*10^-6 1/s^2) (for altitudes below sea level, the Bouger correction is subtractive). This method is valid for altitudes near sea level. As is noted in Gravimetry, even on the surface, the Earth's gravity varies.

For intermediate distances (a few kilometers to several radii) various multipole contributions are non-trivial. For longer distances, the multipole components become negligible and one is left with Newton's law of universal gravitation.

For vastly more information about gravity, see the gravitation portal. -- Fuzzyeric 00:20, 14 September 2006 (UTC)

Carbon dioxide

With the growing scare in some social circles of the changing temperature on earth, carbon dioxide is constantly brought up as a greenhouse gas that needs to be cut down on. My question is would it be possible to somehow suck (extract) carbon dioxide from the atmosphere and put it in a solid state? - Tutmosis 01:23, 7 September 2006 (UTC)

Try Carbon dioxide sink#Artificial sequestration and Carbon capture and storage. Melchoir 01:27, 7 September 2006 (UTC)

There's way too much in the air for us to ever remove a significant portion with machinery. However, natural removal of carbon dioxide could be increased by increasing the number of land and/or sea plants. For example, algae growth could be encouraged by adding iron to iron-poor sea water. StuRat 02:22, 7 September 2006 (UTC)

I think that's been tried (dumping iron in the sea that is). I think I read about it in Discover magazine; can't remember exactly, but I think it didn't work out too well. (P.S. I think therefore I'm really not certain.) Clarityfiend 04:11, 7 September 2006 (UTC)

You are uncertain, therefore you are. DirkvdM 10:39, 7 September 2006 (UTC)

Yes it has been tried, with mixed interpretations regarding the outcome. More information and links to some of the studies can be found in the articles on Iron fertilization and Iron fertilizing (it has been suggested to merge the two articles). ---Sluzzelin 09:38, 7 September 2006 (UTC)

• There's an easy natural way of removing carbondioxide from the air which has the nice side effect of producing oxygen. It's called trees and if less of those were cut down and more of them were planted, things might be looking up... =- Mgm|^(talk) 07:23, 7 September 2006 (UTC)

See Carbon dioxide sink#Enhancing natural sequestration for that. Not just trees, but plants in general. But their presence alone doesn't do the trick. They need to grow to absorb carbon. So we need fast growing vegetation. Trees are a bad choice for that. Weeds would be better. Of course a useful weed (feel it coming?) would be best. Hemp is a good one. It grows extremely fast and has many uses. Burning it would undo the effect, so that's a bummer for the potheads. But it is also a good source for fibers. Actually, it used to be grown extensively throughout the world for that purpose (for the sailing industry for example), but got discredited because of its 'medicinal properties' (actually, DuPont pushed that to get rid of the competition for their plastic, but that's a differnt story). It also consumes a lot of Nitrogen, which is present in pig poo, of which we have an excess here in the Netherlands, so we would be an excellent choice for doing this (yeah, right, great excuse I hear you think, but its a different variety of the plant I'm talking about here). Another use is for oil, which can also be used as a fuel. That way it gets burned and the CO2 is released back into the atmosphere, anulling the effect, but if it is seen as an alternative to fossil fuels, no CO2 is added the atmospehere - the net result is zero. It's an oil so it should fit into the existing infrasturcture quite well. And the oil company that seems to be most into alternative fuels, Shell oil, is also Dutch, so I wonder if they're looking ito this. DirkvdM 10:39, 7 September 2006 (UTC)

Carbon was/is stored in a solid state in coal, and in a liquid state in oil. The problem is we're releasing that stored carbon. If we could just stop and wait a few million years, maybe more will be laid down... I wonder if, like coal, any solid form we found would be a good fuel, and thus potentially released by later generations? Skittle 10:57, 7 September 2006 (UTC)

I understand that diamonds will burn, under the proper circumstances, in case using $100 bills for toilet paper has lost all it's novelty. :-) StuRat 01:47, 9 September 2006 (UTC)

pray mantis

how do you identify the gender of a pray mantis insect

It's called a praying mantis. StuRat 01:33, 7 September 2006 (UTC)

Preying mantis might be better considering the following discussion. DirkvdM 10:51, 7 September 2006 (UTC)

Well, they are carnivores (insectivores, to be specific), so they do prey on other insects, but the name is due to their stance, which resembles the common praying stance for people. It's name is an interesting example of anthropomorphitization.StuRat 17:13, 7 September 2006 (UTC)

I believe if you know the species (which is very hard to do), then size plays a major role. I think females are much larger. --liquidGhoul 01:41, 7 September 2006 (UTC)

Size is the best way — [Mac Davis] (talk) (Desk|Help me improve)

Is it true that the female mantis sometimes eats the male after the dirty deed? Or is that a myth? That would be one rather final way of determining the male. Clarityfiend 04:08, 7 September 2006 (UTC)

The article's talk page has a bit of discussion on that. Given the commonness (is that a word?) of the story, the article really ought to address it one way or the other. Melchoir 04:18, 7 September 2006 (UTC)

As always, a great place to go for this kind of stuff is The Straight Dope. Do they have an answer for this one? Yes, they do. EWS23 (Leave me a message!) 05:08, 7 September 2006 (UTC)

Yuck! Thank god I'm not a praying mantis. Clarityfiend 05:53, 7 September 2006 (UTC)

Clarityfiend, you must have missed the article on precisely this topic in Tuesday's Science Times (a regular weekly feature of the New York Times). ---CH 07:52, 7 September 2006 (UTC)

I'm a typing man-tis, ready to figuratively bite off the heads of those who want to impregnate Wikipedia with their POV and lousy prose. Clarityfiend 16:36, 7 September 2006 (UTC)

Possibly I'm being pedantic, but size is only a partial answer, because it's only helpful when used as a comparative. If you had just one specimen of a particular type of praying mantis, (or, for that matter, several hundred all the same size) you wouldn't be able to tell if it was (they were all) male or female. Any other ideas? --Dweller 09:44, 7 September 2006 (UTC)

That's why I said you need to know the species, and obviously their sizes. The females are usually considerably large enough to differentiate. If you get a small praying mantis, it may just be a small species, not neccessarily a male. --liquidGhoul 09:49, 7 September 2006 (UTC)

Vivisection! — [Mac Davis] (talk) (Desk|Help me improve)

Water Ananlysis

Hi, I want to test drinking water with ref. to Hardness, Chloride content & free chlorine content pls. provide me the procedure for same however it should be volumetric analysis...

Thanks & Regards,

Anant BendigeriPatil. +919881271587.

Hmm, I can help you with the water hardness. Obtain samples, say 50ml, add 10ml ammonia and solochrome black indicator, and titrate with c. 0.01M EDTA. n(EDTA) will equal n(Ca) [a reasonable indicator of hardness]. BenC7 10:32, 7 September 2006 (UTC)

Cyclone/Tornado

I was wondering what the difference between a cyclone and a tornado is.Do cyclones have a funnel like tornadoes do?Andreamiller 10:43, 7 September 2006 (UTC)

This is an ancyclopedia. See cyclone and tornado. The main differences (I believe) are size and duration and the fact that cyclones start over sea. DirkvdM 10:54, 7 September 2006 (UTC)

Thanks,I did actually read both the articles.But my main question was whether cyclones had a funnel or not.Serenacw 10:58, 7 September 2006 (UTC)

No, in the usual sense of the word, a cyclone is a hurricane, which has an eye in the center, not a funnel. However, the word "cyclone" is misused to mean tornado in parts of the US. StuRat 12:02, 7 September 2006 (UTC)

To be fully correct (from cyclone):

Cyclones are responsible for a wide variety of different meteorological phenomena such as tropical cyclones and tornadoes.

So, a tornado is a form of / caused by a cyclone in the formal sense. All cyclones have a rotation, though not all will have "funnels" in the usual sense. And of course, Stu is absolutely correct about colloquial usage tending towards tropical cyclone. — Lomn | Talk 13:26, 7 September 2006 (UTC)

Molecule Diagrams

What are some good programs for drawing 2D molecules (especially organic ones)? What is generally used for Wikipedia? How about 3D molecules? Thanks --Russoc4 14:01, 7 September 2006 (UTC)

See the "Drawing molecules" section above. --Andreas Rejbrand 15:17, 7 September 2006 (UTC)

Oops...sorry. --Russoc4 16:19, 7 September 2006 (UTC)

donations to medical science

I am 80 years of age female (4 children)widow and have had several surgeries. at this time i have 6 incurable conditions in my brain. i think that would make my body a good prospect for worthwhile study. i asked my doctor how to do that and he said my drivers license. surely not! so i am asking help to find out how to donate my body to medical science at my graduation to heaven !

my email is (E-MAIL REMOVED) and my mail address is (ADDRESS REMOVED).

if you cannot help me, please suggest another place at whick i can inquuire for help. thank you

signed.................elaine harbour

Dear Elaine,

I think that your doctor was referring to the "donor" checkbox that many U.S. licenses have on them (in California, it is a little pink sticker; in Massachusetts, it is printed onto the license itself). Each state does it a little differently.

I've Googled around Oklahoma's donor options and haven't found one that works through the DMV though. The two best places to contact might be a company called LifeShareRegistry, which is specifically for organ donation but might know about other donor arrangements, and Oklahoma State University's Center for Health Sciences Body Donation Program. Both of these places could probably point you in the right direction in respects to Oklahoma's specific donor procedures. I commend you on your desire to aid medical science. Thank you. --Fastfission 14:37, 7 September 2006 (UTC)

Of course Elaine thinks she's going to get emailed or written to, so she's not actually likely to come back here (and would probably struggled to find her way back here if she wanted tó, if she's a Wikipedia noob). --Username132 (talk) 18:34, 7 September 2006 (UTC)

So who's going to be the good Samaritan and email her the link to her comment?  freshofftheufoΓΛĿЌ  02:32, 8 September 2006 (UTC)

• I'll do it if I can track down the email adress in the history. - Mgm|^(talk) 07:40, 8 September 2006 (UTC)

This diff. Delete it if you don't need it anymore.  freshofftheufoΓΛĿЌ  12:54, 8 September 2006 (UTC)

Why [is] glass transparent?

fixed by LeyteWolfer 17:08, 7 September 2006 (UTC)

See transparency and glass--Light current 17:12, 7 September 2006 (UTC)

Because if it weren't I wouldn't be able to read this. DirkvdM 18:59, 7 September 2006 (UTC)

And we all know the rules of the universe were written so that Dirk could do what he wants to do, when he wants to do it. ;o) EWS23 (Leave me a message!) 19:23, 7 September 2006 (UTC)

Haha! It's the anthropic principle. -- SCZenz 02:06, 8 September 2006 (UTC)

Indeed. We use glass because it's transparent. – b_jonas 21:11, 8 September 2006 (UTC)

Glass *Isn't* transparent. Use a Thermal IR camera to look around, and you'll find that glass is shiny and opaque, like a mirror. Now garbage bags, plastic shopping bags, etc., those this are totally transparent.

A partial answer is that the band gap structure of glass doesn't have absorbances in the visible spectrum. See also absorption spectrum. The absorption spectrum is related to the (frequency dependent) refractive index, which describes the effect using the phrase "radiation from oscillating material charges will modify the incoming wave". Note that for very high indices of refraction, the Fresnel equations predict that a large fraction of incoming light will be reflected (as does glass in the mid-IR). -- Fuzzyeric 00:31, 14 September 2006 (UTC)

Sailors' Dead Winds

What are the things called where sailors would get stuck with out trade winds for days?

• Perhaps you are referring to the Doldrums? --Nebular110 17:54, 7 September 2006 (UTC)

• Doldrums. LeyteWolfer 17:54, 7 September 2006 (UTC)

No, that's a specific region where that phenomenon often occurs, but the question was for the name of the phenomenon. The answer is at the tip of my tongue, but can't break that barrier so to say. :) Then again, the question is specifically about the trade winds, so that's confusing. Anyway, that excludes the doldrums, because that is the area around the equator where there are no trade winds (if I understand it correctly). DirkvdM 19:11, 7 September 2006 (UTC)

I'd imagine the original poster was probably referring to the doldrums or the horse latitudes. If there's a word for the actual occurence of getting stuck there, as Dirk suggests, I haven't heard of it. EWS23 (Leave me a message!) 19:27, 7 September 2006 (UTC)

I'd say becalmed would be a fairly accurate description. GeeJo ^(t)⁄_(c) • 20:25, 7 September 2006 (UTC)

To be in the doldrums is to be becalmed surely?--Light current 02:37, 8 September 2006 (UTC)

Probably. But to be becalmed is not necessarily to be in the doldrums, particularly if you happen to be 1000 miles away at the time. JackofOz 04:04, 8 September 2006 (UTC)

Dead Calm

Handwashing

Can I hand wash clothes using regular (designed for washing machine) detergent, so long as I wear rubber gloves? --Username132 (talk) 18:26, 7 September 2006 (UTC)

I suppose you could, but liquid dish washing detergent works better for hand washing laundry. StuRat 18:48, 7 September 2006 (UTC)

Wouldn't that fade or otherwise damage the clothes? --Username132 (talk) 19:12, 7 September 2006 (UTC)

No, dishwashing detergent is much more gentle on clothes than laundry detergent, and some is even labeled "for use with delicate hand washables". The only concern might be that it would be less effective at removing serious stains, so I'd use a stain spray for that. StuRat 06:04, 8 September 2006 (UTC)

Yes you can, and personally I think laundry should be washed with laundry soap, and dishes should be washed with dish soap, and not vice-versa. :-) Anchoress 18:51, 7 September 2006 (UTC)

I have done that regularly when travelling. I supose it's not too good for the hands, so don't do it too often. Actually, in Cuba I got these areas of hardened skin that the doctor detected when I visited her for something else. It was easily soved with some ointment (can't remember what), but she told me to better not wash by hand. An overcautious doctor, I suppose. Funny StuRat mentions dishwashing detergent, because I use that for everything but my laundry (and my body). So I can now do away with the clotheswashing detergent as well? Less practical for travelling, though because it's a fluid and therefore too heavy. DirkvdM 19:16, 7 September 2006 (UTC)

You can use dishwashing detergent as emergency body soap and/or shampoo, too, but you need to dilute it with water first, or it's difficult to rinse off. I've used it myself when I ran out of the normal stuff, and it worked fine. StuRat 03:37, 10 September 2006 (UTC)

When traveling, I have used bath soap to wash clothes, and that works okay, too. It also doesn't really require gloves. Marco polo 19:43, 7 September 2006 (UTC)

Couldnt you do it by just having a bath with your clothes on?--Light current 01:41, 8 September 2006 (UTC)

Yes, but you're not going to enjoy the next thirty minutes in the dryer very much.--192.168.1.1 05:19, 8 September 2006 (UTC)

Actually, I met soneone who travelled with one set of clothing who did just that. In the tropics it can be wonderful to walk around in wet clothes. DirkvdM 07:07, 8 September 2006 (UTC)

Portal to define pictures of plants or animals

Hello, is here in the english Wikipedia a Portal to define pictures of unknown plants or animals, like in the german Wikipedia? Greetings --Ruestz 19:00, 7 September 2006 (UTC)

You could also upload to Wikimedia Commons (which is a better place to put photos because from there they can be accessed from any wiki project) and then place them at http://commons.wikimedia.org/wiki/Category:Unknown_species. try to put them in the most specific category you can find. Alternatively, ask at the most relevant talk page. By the way, the word is not 'define' but 'determine'. Wie auf Deutsch glaube ich, 'determinieren', nicht? DirkvdM 19:27, 7 September 2006 (UTC)

People usually just ask here, or on Wikipedia talk:WikiProject Tree of Life. There's no definitive place as far as i know. —Pengo ^{talk · contribs} 14:25, 9 September 2006 (UTC)

Thank You for the informations --Ruestz 22:32, 9 September 2006 (UTC)

Kuiper belt

The article states the majority of Kuiper belt objects were found after 1992, but it does not elaborate on why that is the case. Could someone please answer that, and place it in the article; as I feel the context would be helpful. - RoyBoy ⁸⁰⁰ 19:49, 7 September 2006 (UTC)

I'd speculate its because either:

• The technology required to see them was not yet available

• No-one looked in the right place at the right time with the right telescope

The reasons why someone didn't find/do something before anyone else is usually speculative and thus may be why it isn't in the article. Still, if anyone can source it... Rockpocket 01:31, 8 September 2006 (UTC)

I'd guess the Hubble Telescope, launched in 1990 and upgraded/corrected with COSTAR in 1993, was the source of this new data, as it was a major improvement over Earth-based optical telescopes. StuRat 05:53, 8 September 2006 (UTC)

I suspect that the Hubble isn't used explicitly for KBO surveys—it's field of view is too narrow and telescope time is too precious to go trolling for asteroids. It's possible that some might be discovered serendipitously while examining other objects. The HST can be used for examining these objects in (more) detail once they have been discovered, however. TenOfAllTrades(talk) 12:31, 8 September 2006 (UTC)

David C. Jewitt and Jane Luu discovered the first Kuiper Belt object in 1992 using a telescope in the Mauna Kea Observatory. Looks like people simply started looking for more. One of the larger KBOs, 90482 Orcus, can be seen in photographs from 1951 but nobody noticed it for fifty years (you can't just look at a photo and go "ha, a new planet!" You need to painstakingly compare many photographs from different times and detect tiny movements of very faint blobs to tell stars and moving rocks apart. You need to know what you are looking for.)

In a Scientific American May 1996 article Jewitt and Luu say that since the initial find a bunch of research groups have joined the effort and found a steady stream of KBOs. Weregerbil 08:46, 8 September 2006 (UTC)

When you mention Jewitt and Luu and 1992, you probably mean (15760) 1992 QB1. But that wasn't the first KBO found. As that article points out, Pluto was first, in 1930, and Charon second in 1978. QB1 was the third. -- Plutortalkcontribs 12:08, 8 September 2006 (UTC)

I think there is a distinction between "KBO found and known to be a KBO" and "discovering something which we now consider a KBO but was at the time considered a planet and a moon". --Fastfission 14:50, 8 September 2006 (UTC)

Indeed. In the last fifteen or twenty years there have been several major advances which have made searching for KBOs much easier. The computer hardware and software for automated image analysis (trying to find the one bright speck that isn't a star or known object) has gotten both better and cheaper. CCDs have become much cheaper and much improved in quality, allowing sky surveying without the messy intermediate steps involving photographic plates. Finally, several medium-large aperture telescopes (0.9 meters and up) have been configured for automated sky surveys in the last fifteen years—nobody's been looking very hard for KBOs until recently. TenOfAllTrades(talk) 12:31, 8 September 2006 (UTC)

Note also that Jewitt and Luu spent five years from the start of their search until success, having to acquire telescope time for this (low-priority) search and using very primitive tools to compare photographs. So, around 1990, it takes five years to find such an object. This includes, in a not well defined way, the effects of funding availabitily, telescope availability, telescope power, computation power, storage requirements, et al. -- Fuzzyeric 00:35, 14 September 2006 (UTC)

One lung breathing

In the show Malcolm in the Middle, the character Stevie has (I think) only one lung and breathes a deep breath after every word. Is this medically correct? Reywas92 19:50, 7 September 2006 (UTC)

Stevie is chronically short of breath because he has severe asthma. I can't comment on the medical plausibility of his case, other than to say that if it were a fair clinical picture, Stevie would represent the more severe end of the chronic asthma spectrum.... TenOfAllTrades(talk) 21:50, 7 September 2006 (UTC)

• I doubt that is possible, Reywas92. One long is not enough to provide the body with the oxygen it needs and he would need to be on constant additional oxygen which he's not. - Mgm|^(talk) 07:36, 8 September 2006 (UTC)

Actually, one lung is enough to provide a person with the oxygen they need. Pneumonectomy (removal of one entire lung) is a surgical procedure for treating advanced lung cancer. Patients with one lung are limited to a modest level of physical activity, but otherwise can lead mostly normal lives. They don't need constant additional oxygen and are not confined to a wheel chair, like Stevie. --Ed (Edgar181) 13:07, 8 September 2006 (UTC)

Yeah, it's possible. Before modern antibiotics, tuberculosis was often treated by artificially collapsing one lung for a few days to create an environment unhospitible to the bacteria. With the plethora of new strains of resistant Tb, you may hear about this procedure in the future too...Tuckerekcut 04:25, 10 September 2006 (UTC)

The Guinness World Record: Bruce Geiling (born June 7, 1923) lost his right lung to cancer on April 10, 1969, and is still leading a healthy life on August 14, 2004. Neal 14:55, 10 September 2006 (UTC). ^ thats my grandpa. He pasted on to heaven on November 27, 2007.

Can guinea pigs eat lettuce?

I read that iceberg lettuce is bad for guinea pigs. Is this true? Reywas92 19:52, 7 September 2006 (UTC)

Iceberg lettuce is pretty low in nutritional value—it's mostly "crunchy water". Neither guinea pigs nor humans get much out of the stuff; we only eat it because it's a convenient vehicle for salad dressings.

In larger quantities, the high water content and (probably) nitrates in the lettuce can cause various sorts of digestive upsets. Small amounts probably won't do any harm, but they're not beneficial either.

Consider something dark green and leafy, instead: kale, dandelion leaves, spinach, clover, or parsley. TenOfAllTrades(talk) 22:00, 7 September 2006 (UTC)

• We used to give our guinea pig nl:witlof. Unfortunately, there doesn't seem to be an English article on the stuf... - Mgm|^(talk) 07:35, 8 September 2006 (UTC)
  • That's Belgian endive. feydey 13:42, 8 September 2006 (UTC)
    • Witloof was a redirect to endive. I've created witlof as one, too. -- Plutortalkcontribs 12:01, 11 September 2006 (UTC)

Yes. I don't know the mechanism behind it, but iceberg lettuce causes diarrhea and/or non-normal feces in guinea pigs and other animals. First hand info, I'm afraid - stick with romaine leffuce.  :-P As an aside, my daughter recently caught a caterpillar and when it refused some of the leafy stuff from outside, we stuck some iceberg lettuce in the terrarium for it - it also had loose feces. Not sure why *I* keep eating it... Matt Deres 19:28, 10 September 2006 (UTC)

How can I, as a white man get natty dreadlocks without having to pay for them?

I know that black ppl's hair naturally forms into dreadlocks if they don't brush or wash it for a long time. Is this true for white people too? How long would it take for the dreads to form if I decided never to touch my hair with anything again (it's already past shoulder length)? Some people might say it's gross to never wash your hair but I heard that the hair starts cleaning itself naturally after a while anyway.

I don't want salon dreads. I can't afford them.

It's not whether or not you wash your hair, it's whether or not you comb it. Here's an article called How To Make Dreadlocks and How To Make Dreadlocks - tips. Maybe that will help. Anchoress 21:34, 7 September 2006 (UTC)

Just completely ignore your hair.. I mean wash it and stuff, but don't hair care it, and it will matt. When it's matted just pull the matt into strands as thick as you want your dreads. Philc _T^E_C^I 21:37, 7 September 2006 (UTC)

So can Chinese people get dreadlocks than? It doens't sound right. — [Mac Davis] (talk) (Desk|Help me improve)

Sure, if they have hair that isn't straight. "It doesn't sound right" because you're not used to it, but I'm sure there are at least a few. ColourBurst 18:41, 8 September 2006 (UTC)

I once met a guy who after hiking through the Tasmanian bush for a few days noticed he couldn't get a comb through his hair. So it was either cut the hair or develop dreadlocks. he chose the latter. I believe something similar happened to Keith Richard.

Yup, it's a matter of not combing your hair. I just wonder if you can 'sculpture' the dreadlocks. What if a dreadlock develops you don't like? Some look messy, others look neat, is there a trick to that? And bums nowadays often have dreadlocks, which makes sense, so it doesn't make sense that that would be a recent phenomemon. So did they have them in previous centuries too? DirkvdM 07:19, 8 September 2006 (UTC)

I haven't combed/brushed my hair in years, and I don't have light, straight hair. I also don't generally "treat" it, just shampoo and the monthly conditioner or so. I had a roommate up until a couple of months ago with huge dreads, and although he washed them, I don't think he did very often. Something like, "When I start to smell it too, that's when I wash".  freshofftheufoΓΛĿЌ  07:28, 8 September 2006 (UTC)

One of us has a nephew who just put toothpaste in his hair. dreadful it was, but it was quite dreadlockish. -- DLL ^{.. T} 16:26, 9 September 2006 (UTC)

What if you don't brush your teeth for a long time? Will you get dreadful teeth then? I suppose so. DirkvdM 08:02, 10 September 2006 (UTC)

Yes. --Proficient 04:52, 11 September 2006 (UTC)

Sodium vs sodium chloride in foods

When a food label in the US (FDA regulated) claims sodium content, do they really mean sodium chloride as in traditional edible salt or is this the mass of any digestible form of sodium in the food? As a follow-up, does the human body use sodium or sodium chloride specifically to regulate hydration? When reading over the articles, it's hard to tell if terms are used loosely. p.s. this isn't homework, I swear! --Jmeden2000 21:31, 7 September 2006 (UTC)

As to the first question, my guess is they really mean sodium, but it's just a guess. The second question I can answer a bit more definitively: When sodium chloride is dissolved in water (as it will be in your body) it dissociates almost completely. So what counts is sodium ion, Na⁺; your body has no way of knowing if it was part of sodium chloride or some other sodium salt. --Trovatore 21:39, 7 September 2006 (UTC)

THe main source of sodium in the diet must be sodium chloride. I cant think of any other sodium salts that we eat in any quantity.--Light current 22:24, 7 September 2006 (UTC)

edit conflict: yeah they mean total sodium content, from salt, baking soda preservatives etc. because it's all sodium in the end. the sodium ion is important, for example in the Na+/K+-ATPase. not to say chloride isn't important too. and i think they measure sodium due to its role in heart disease, but i'm unsure. Xcomradex 22:29, 7 September 2006 (UTC)

and just for light current: sodium bicarbonate, sodium benzoate, monosodium glutamate... Xcomradex 22:29, 7 September 2006 (UTC)

Apart from monosodium glute a mate (used as flavor enhancer). How much sodium bicarb and sodium bezoate do we eat?--Light current 22:33, 7 September 2006 (UTC)

• sodium benzoate: FDA maximum of 0.1% w/w
• sodium bicarbonate: from cookbooks seems about one teaspoon (5g)/ cake

bear in mind we don't usually put a lot of salt on meals in w/w terms. but is still probably the major source, due to its ubiquity. Xcomradex 23:08, 7 September 2006 (UTC)

1gm NaCl contains 0.4 gm sodium--Light current 23:31, 7 September 2006 (UTC)

it does, but remember we don't put 1g salt on a 100g steak. Xcomradex 01:06, 8 September 2006 (UTC)

I dont put any on. But there again I dont eat steak.--Light current 01:08, 8 September 2006 (UTC)

By the way, the unit sign of "gram" is g. gm is "mostly obsolete" when referring to grams, unless you were actually talking about giga-meters.  freshofftheufoΓΛĿЌ  02:24, 8 September 2006 (UTC)

Gm is used for Gigameters. StuRat 00:42, 10 September 2006 (UTC)

THanks for that 8-)--Light current 02:25, 8 September 2006 (UTC)

Sodium is what's used for hydration. Chloride is the most important anion in the body because it is the most common. However, the sodium is what's regulated and the chloride usually just follows! InvictaHOG 09:56, 8 September 2006 (UTC)

Follow up

First of all thank you to all who answered, this has been most informative. I would like to add another sub question: how do you suppose all animals developed a heavy reliance on sodium if it is so rare to occur in plants? (as per the sodium article). Surely primitive mammals were not digging salt mines or evaporating sea water... So where in the food chain does it all come from? --Jmeden2000 17:22, 8 September 2006 (UTC)

Salt lick. --Serie 19:34, 8 September 2006 (UTC)

While life evolved in the ocean, where there is plenty of salt, I agree that it does seem odd that, once animals moved onto land where salt is scarce, they weren't able to evolve to better match this low salt diet. I would have to conclude that it's just extremely difficult to break this dependency. StuRat 21:42, 8 September 2006 (UTC)

thats right sturat. the sodium ions are used to produce a concentration gradient across the cell membrane, which then allows essential compopunds such as amino acids to be brought into the cell and concentrated by active transport, with the change in sodium concentration making the whole process positive in entropy terms. the system is of such a fundamental importance, i'd doubt whether the necessary genetic variation could exist for evolution to occur. Xcomradex 22:39, 8 September 2006 (UTC)

I thought it might be useful to add sodium sturate in a regular diet. -- DLL ^{.. T} 15:21, 9 September 2006 (UTC)

Mutism

I recently watched a TV drama in which one of the main characters got in some kind of accident and lost her hearing. She chose to start using sign language exclusively because she couldn't hear the sound of her voice and was ashamed about the way she assumed it would sound. That said she did talk occasionally during the show, with a very nasal voice, the kind one might usually associate with a person unable to hear from birth. I'm not sure how realistic the drama is supposed to be, but I'd be a little shocked if there was such a big misconception as that. Do (could) people who become deaf (suddenly?) lose the ability to speak in a fashion that they were able to before they became deaf? I couldn't find any mention of it at speech disorder or deaf culture.  freshofftheufoΓΛĿЌ  22:21, 7 September 2006 (UTC)

I've heard radio-interviews with people who lost their hearing and their speech was completely 'normal' and melodious to my ears. Singing, where the frequencies and modulations have to be more accurate, is a different thing; I distinctly remember listening to a woman who had lost her hearing years ago sing Amazing Grace, and it was hard to recognize the melody. Percussionist Evelyn Glennie almost entirely lost her hearing at the age of twelve and speaks like a hearing Scottish person too, as can be heard in the documentary film Touch The Sound. ---Sluzzelin 05:59, 8 September 2006 (UTC)

The problem with that, I guess, is that deafness usually isn't absolute, and at least some of the people you mentioned might have some awareness of the sounds coming from inside their bodies (Evelyn Glennie's article notes that she has "very limited hearing"). Failing that, it seems that at the very least it may not be expected for someone to lose the ability to speak properly along with their hearing, though I wonder if there are exceptions. I actually quite liked the drama so I kind of want it to not be a complete farce!  freshofftheufoΓΛĿЌ  07:11, 8 September 2006 (UTC)

This is also why singers (and instrumentalists for that matter) need feedback through a monitor on stage. If they can't hear their own voice they can't sing in tune. I wonder if classical singers before a full orchestra (which can be a lot louder than a rock band) use this too. I don't recall ever seeing it. DirkvdM 07:25, 8 September 2006 (UTC)

No they dont. THey can belt it out at much higher levels than pop singers so they can hear themslves ok. Also the orch tends to come down under the singer a bit.--Light current 07:38, 8 September 2006 (UTC)

(Edit conflict) You're right. And a further difference to the TV drama, is that most people lose their hearing gradually, allowing them to closely monitor and correct changes in their speech. Googling "traumatic mutism" or "post-traumatic mutism" leads you to some neurological websites discussing this phenomenon. In the cases I found, mutism was explained psychologically and not linked to the loss of sense of hearing.---Sluzzelin 07:34, 8 September 2006 (UTC)

Ok ok, but I'm losing the original question. I don't think there was any post-traumatic mutism or anything like that, the show explained her "nasal speech" to the extent that it was only a concequence of her loss of hearing, which in turn was caused by some sort of car accident I think. Anyway, I think it's pretty clear that this drama was a little bit scrubbier than I initially thought. Loss of tone recognition doesn't really explain either why she would suddenly sound nasal. Oh well, thanks guys!  freshofftheufoΓΛĿЌ  12:03, 8 September 2006 (UTC)