Science desk
< March 24	<< Feb \| March \| Apr >>	March 26 >

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

March 25

Mental illness rates by US state

I have always heard that the southern states, especially La., Ark, and Mississippi have the highest incidence of Chronic Mental Illness like Schizophrenia, Bipolar, Obsessive/ Compulsive and eating disorders. Is this true? or which states do typically have highest rates?

Sounds like Yankee propaganda. What state has the highest oncentration of psychiatrists? Edison 04:45, 25 March 2007 (UTC)[reply]

Off-hand, Edison, I would think Massachussetts. I don't have a statistic to back it (though I guess we could find one). Nimur 07:59, 25 March 2007 (UTC)[reply]

[1] Massachusetts ranks 1st in psychiatrists and 3rd in psychologists per Capita. Once again my unfounded, gut-instinct is proven correct by official-sounding government statistics. Nimur 08:02, 25 March 2007 (UTC)[reply]

I note for the sake of completeness that such a statistic may only indicate that Massachusetts has the best mental health care in the nation; you would need to look at statistics for diagnosis of illness rather than number of doctors, yes? Of course, the number of diagnoses is likely to be skewed upwards by the larger number of mental health professionals and by the high average personal income in the state (higher income in the U.S. usually translates to better access to medical care). Mass. is third in the nation for number of dentists per capita too; do they have the third-worst or third-best teeth in the nation? TenOfAllTrades(talk) 13:12, 25 March 2007 (UTC)[reply]

Here are some surveys, a couple of which might help you determine the answer to your question.[2] The raw data for at least some of these are publicly available, but you may need to do your own analysis of the raw data. I think perhaps your best bet here might be the Epidemiologic Catchment Area Survey, whose raw data is available here.[3] The good thing about the ECA is that it's designed to measure the actual incidence of various mental illnesses, as opposed to something like the Census of State and Federal Adult Correctional Facilities, which instead measures percentages of inmates who receive mental health services, which could paint a different picture. The advantage of the CSFACF is that data is available by every state, unlike the ECA, for which data is available only for the five "catchment areas". But one of the catchment areas is in North Carolina, which is fairly southern, so it should help test your hypothesis if you compare the North Caroline data with the data from the catchment areas in the other four locations in the country. At first glance, it looked like the best nationwide data for non-inmates would be the National Comorbidity Survey and the National Comorbidity Survey Replication. Unfortunately, although the NCS and NCS-R gather data from 48 states, the state is not one of the fields available in the publicly available data. MrRedact 15:20, 25 March 2007 (UTC)[reply]

Electromagnetic Spectrum

What are the different types and uses of radiation that make up the electromagnetic spectrum?

See: Gamma ray • X-ray • Ultraviolet • Visible spectrum • Infrared • Microwave • Radio waves →Ollie (talk • contribs) 03:43, 25 March 2007 (UTC)[reply]

And don't neglect audio frequency (baseband) waves, as in the Nathan Stubblefield article. And also sub-audible waves. Edison 04:43, 25 March 2007 (UTC)[reply]

Little nit pick: I don't think you meant to imply this, but audible waves are mechanical vibrations, not electromagnetic radiation. Light can indeed come in audio-range frequencies (SLF, ULF, VLF), but you wouldn't be able to hear it. -- mattb @ 2007-03-25T23:53Z

Perhaps you should take a look at the article on light, which encompasses all of the electromagnetic spectrum (though you may not usually think of radio waves as light, they are). -- mattb @ 2007-03-25T04:57Z

To be nit-picky and boring, many people don't think of radio waves as light because some definitions of light only include the visible (or near-visible) spectrum, so radio waves aren't light.. depending on which definition you care for. —Pengo 12:21, 25 March 2007 (UTC)[reply]

True, but given our current understanding of the quanta of light, I think it's pretty accurate to cover the entire electromagnetic spectrum under the term. Most physicists and research scientists I know seem to follow this logic. If EUV and far IR are usually called light, I don't see much reason why X-rays and EHF radio waves shouldn't be. -- mattb @ 2007-03-25T22:59Z

Here's the U.S. allocated spectrum of 300 to 3000MHz and here's the chart from 1928. Here is a really cool but exceptionally geeky poster that you can actually order from NITA. (In logic that only Governments can explain the NTIA publishes the spectrum but the FCC allocates and regulates it.) --Tbeatty 05:36, 25 March 2007 (UTC)[reply]

What's "exceptionally geeky" about that? That's a great poster! Nothin' but cool about it! :-)

(There was another great one, published by some company that made tools for network monitoring, that showed all the Internet protocols and how they interrelated. Anybody remember it? There was a copy kicking around at a company I used to work for, that I meant to steal or at least jot down the provenance of, but I guess I never did.) —Steve Summit (talk) 13:42, 25 March 2007 (UTC)[reply]

Or, you could look at the overview article at Electromagnetic spectrum. -Arch dude 14:36, 25 March 2007 (UTC)[reply]

Crap. I spent half an hour searching for that chart. I even uploaded it to Wikipedia when I found it. File:Allochrt.pdf. I put it in the Frequency allocation article. --Tbeatty 23:04, 25 March 2007 (UTC)[reply]

kidney

are the two main types of cells of the renal medulla the chromaffin and postganglionic cell? anyone know where to get more information on this, seems the wiki article doesn't mention much.

The kidney has a number of cell types and lineages. In the medulla one will find many subtle gradations of epithelial cells in the different sections of the nephron, and the blood vessels. The bowman's capsule/glomerulus has specialized filtration equipment (beyond fenestrated epithelium and tightly regulated basement membrane) in the podocyte cell. The juxtaglomerular cells are very sensitive to endogenous pressors and control blood flow through the afferent arteriole. THis is far from an exhaustive list. The two types of cells you describe are not particularly relevant to the kidney. The chromaffin cell is specific (mostly) to the medulla of the suprarenal gland. Postganglionic cell refers to parasympathetic neurons which receive information from the preganglionic fibers. Postganglionic cell bodies are found within the ganglia themselves. ^tucker/_rekcut 15:05, 25 March 2007 (UTC)[reply]

sorry got the kidney bit mixed up...the andrenal medulla is what i want to know about.

Then look at the adrenal gland and adrenal medulla articles and you will find the answers. alteripse 20:19, 25 March 2007 (UTC)[reply]

Ergography

I am a second year MBBS student. I want to know that handgrip ( Mossos ergograph) is isometric excersice or isovolumetric excersice, and does it have any relation with blood pressure. I have performed experiment with 30 subjects, and found that systolic blood pressure increases after performing handgrip ergography, but diastolic pressure remains almost same, which is characteristics of isovolumetric excersice. But I strongly feel that handgrip excersice is isometric excercise (static excersice) where both systolic and diastolic bp should increase.

THANK YOU.

—Preceding unsigned comment added by 203.94.218.27 (talk • contribs) 11:31, 25 March 2007

The hand grips moves so it is not an isometric exercise. I don't know about isovolumetric exercise - is that where the muscle keeps the same volume? (which it always does in the short term!) When gripping a bar it does not move, so that would be isometric exercise. Not many muscles are involves - so are you sure that your subjects are not tensing up some other muscles too? I can't find an article on hand grips so perhaps this is an opportunity for you to write one! GB 21:50, 25 March 2007 (UTC)[reply]

helpppppppppppppppp

what's the difference between a mouse, a mice & a rat???????? —Preceding unsigned comment added by 124.7.67.85 (talk • contribs) 13:34, 25 March 2007

A mouse is a mouse (follow the link for more information).

'Mice' is the plural of mouse.

A rat is a rat. TenOfAllTrades(talk) 13:39, 25 March 2007 (UTC)[reply]

Good thing you cleared that up. :-) —Steve Summit (talk) 13:48, 25 March 2007 (UTC)[reply]

Or Mouse and rat :@ HS7 15:05, 25 March 2007 (UTC)[reply]

Rats are generally larger than mice. Or, if you want a huge rat-like rodent, how about nutria ? StuRat 19:19, 25 March 2007 (UTC)[reply]

...and this rat is known to use a mouse. :-) StuRat 19:15, 25 March 2007 (UTC)[reply]

β

I really need some help with this as soon as possible. Yes it is homework, but I am supposed to look it up on the internet, and don't have a clue where to start, so I came here. I have to find out how someone would go about calibrating a device that measures distances accuratly using a βsource and a βdetector, and what results they would expect from calibrating it. Also can anyone tell me what it means by what results they would expect, I really haven't got a clue. This is really important work and I need proof that I have done something by tommorow. HS7 13:52, 25 March 2007 (UTC)[reply]

Well, the amount of beta radiation you detect would reduce as some function of the distance from the source. That's going to be due to the inverse square law - modified by the rate of absorption of beta radiation by the air. So I suppose you could take your beta source and place the detector some known distance from it and measure the amount of radiation. Then (since we don't know the exact relationship between amount of radiation and the range) the smart answer for this question would be to measure the amount of radiation measured at a variety of distances from the source and plot a graph (hint: use log-graph paper!) - from which you can do a curve-fit and deduce the rate of falloff of radiation with range - which you can use to deduce the range to an unknown position if you measure the radiation. The result of ought to be (drum roll please) an inverse square law because beta particles aren't blocked significantly by the air and almost everything like that obeys an inverse square dropoff rate for simple geometric reasons. SteveBaker 17:27, 25 March 2007 (UTC)[reply]

Still don't have a clue :( No, really I think I get most of it, but I don't know what an inverse square or log graph paper is :( What about measuring the distance, would a normal ruler be accurate enough :) HS7 18:34, 25 March 2007 (UTC)[reply]

The inverse square law article explains it. If you want to get a quick understanding of the law, do a google image search. Diletante 23:26, 25 March 2007 (UTC)[reply]

THe inverse square law says that the amount of radiation received by a detector with a given surface area is proportional to one divided by the square of the distance. So if you got X amount of radiation one meter from the source then you'd have X/2² units at two meters, X/10² at 10 meters and so on. If you plot a graph of amount of radiation versus the distance on ordinary graph paper, you'll get a nice curve - but it's hard to fit an equation to that curve. The traditional way to fit an equation to most kinds of curve is to plot the log of the amount of radiation against the range - which gives you a nice straight line. Measuring the slope of the line lets you figure out that this is indeed an inverse range squared kind of thing. These days, I suppose you might feed the raw data from your calibrations into a computer program to figure out the best fit equation - but I doubt that's what they are trying to teach you in class. As to whether you can use a ruler to measure the distances? Well, yes, you could - but then the graph you'd plot and the equation you'd estimate and the resulting ranges that you'd measure with the calibrated device - would only be as accurate as your initial measurement with the ruler. So if you planned on using this contraption to measure distances of a few meters to a precision of a few millimeters - then using a ruler would be fine - but if you needed much greater precision in the results - then your calibration would have to be done more carefully. Since you talk about "a device that measures distances accuratly" - I presume you are supposed to be getting accurate results - so maybe a ruler isn't good enough. But I can't say for sure because I'm not aware of how precise such a device would be in reality. SteveBaker 03:55, 26 March 2007 (UTC)[reply]

What plant is this?

I took the picture Image:Paprika.jpg and uploaded it a while ago. I thought it was a paprika plant, but it seems it's a citrus plant, not paprika. I've had both citrus and paprika plants in the past and now I'm unsure of which this one was. Does anyone know for sure? Entheta 14:25, 25 March 2007 (UTC)[reply]

Looks like a citrus to me, rather than a capsicum plant. Look at the lower pictures - you can see the leaves are more pointed on the paprika plant. GB 21:58, 25 March 2007 (UTC)[reply]

I've moved it to Image:Citrus plant.jpg as per the standard procedure. Nimur 07:17, 27 March 2007 (UTC)[reply]

physics

How does a heavy boat float on water? —Preceding unsigned comment added by 206.40.212.89 (talk • contribs)

There is an explanation in our article on buoyancy. Gandalf61 17:09, 25 March 2007 (UTC)[reply]

It's all about 'displacement'. Things float when the amount of water they push out of the way weighs as much at the object itself does. To figure out whether a heavy object will float, you need to divide it's weight by it's volume to obtain an average density - and compare that to the density of water. So whilst steel is much denser than water, and a huge steel ship is very heavy indeed, the hull encloses a lot of air too - so the average density of the ship is less than water.

Frequency and Tapering

Greetings... Almost all resistive elements in the high power high frequency(oil cooled or forced air cooled) RF Load are inside a tapered housing... So does the dimensions of the tapered housing be changed for different frequencies or the resistive element will work efficiently for different frequencies for the same dimension housing???

-unsigned question

Dummy loads can be very broadband, the shape of the container has little to do with it. The volume will determine the amount of energy you can absorb in a short time, and the surface area, how much power you can dissapate over a long period. The shape of the resistor inside will limit the upper frequency. If it is coiled it will not work well in the microwave region. Also the kind of coupling joint can limit the frequency, as you will need a suitable interface to get poin into it. An N-type is good. GB 22:03, 25 March 2007 (UTC)[reply]

When you say "high frequency" are you using the word "high" in a general sense, or are you talking about the HF band (3-30 MHz)? If you're talking about the HF band, e.g. you're setting up an amateur radio transmitter, then the wavelengths involved are in the 10m to 100m range, so the shape of the housing isn't particulary important, because the dimensions of the housing are very small compared to the wavelengths involved. If you meant "high frequency" in a general sense, e.g. you're setting up a radar transmitter, then the ratio of wavelength to housing dimensions might be small enough that the housing is functioning as a wave guide, so its shape would make a difference. What frequencies are you dealing with, and how big is this housing you're talking about? MrRedact 00:51, 26 March 2007 (UTC)[reply]

Thanks for the response... I am talking of very high frequency in a very wide band range... 500 to 1000 MHz... The housing will be according to the dimensions of the resistor element used. The element used for such frequencies is about 10 inches in length and a dia. of 1-1.5 inches... What do you suggest for that ? Bhavikmehta2685 07:30, 28 March 2007 (UTC)[reply]

interpreting tensors

I'm a rank beginner on the subject of tensors, but from what little I understand the page on Euler equations is wrong in saying that

{\partial \rho {\mathbf {u} } \over \partial t}+\nabla \cdot ((\rho \mathbf {u} )\mathbf {u} )+\nabla p=0

is equivalent to

{\partial \rho u_{j} \over \partial t}+{\partial \rho u_{i}u_{j} \over \partial x_{i}}+{\partial p \over \partial x_{j}}=0,

presumably for all $i$ and $j$ . Shouldn't this be

{\partial \rho u_{j} \over \partial t}+\sum _{i=1}^{3}{\partial \rho u_{i}u_{j} \over \partial x_{i}}+{\partial p \over \partial x_{j}}=0

for $j=1,2,3$ or am I completely on the wrong track? 84.239.133.38 17:34, 25 March 2007 (UTC)[reply]

See Einstein notation.

I am not sure how it is relevant here. Do you mean that

\partial u_{i}

in the nominator and

\partial x_{i}

in the denominator count as different terms that imply summation in the Einstein notation? 84.239.133.38 21:46, 25 March 2007 (UTC)[reply]

It's not that they're different terms; it's just a type of notation, as explained at the page linked above. When two variables share the same subscript, in a single term, then a summation of the form you've written above is implied. The three equations you've written down are all equivalent, but this way you're saved from explicitly writing down the summation every time. It's a very convenient shorthand. Spiral Wave 23:56, 25 March 2007 (UTC)[reply]

Ok, thanks. 84.239.133.38 06:47, 26 March 2007 (UTC)[reply]

You might get better answers from the math heads on the Math Desk -- Diletante

This abbreviated tensor notation is called summation convention and the variable $i$ is called a dummy variable. GB 09:14, 26 March 2007 (UTC)[reply]

Apple tree

I planted an apple in the fall, will a tree grow, if not, why?Elatanatari 18:21, 25 March 2007 (UTC)[reply]

It might or it might not, it depends how lucky you are, and what weather you have :) 172.215.71.82 18:31, 25 March 2007 (UTC)[reply]

And, all commercial apples are cloned by grafting from the original, say, McIntosh or Gala, tree because apples don't "breed true". If you get apples they won't be what you planted. There's a story that an apple merchant carried around a name for when he came across the right apple, hence "Delicious". Keep an eye out, you may be the next Granny Smith. --Saintrain 19:49, 25 March 2007 (UTC)[reply]

The two most important factors are soil type and climate. So, where do you live? Vranak 03:42, 26 March 2007 (UTC)[reply]

Apple seeds don't germinate when you just bury an entire apple. The way those kinds of fruit seed spread is by being eaten by some animal that chews up the apple and swallows the seeds. The seeds pass through the gut unharmed and are deposited onto the ground in a convenient gooey pile of manure a good distance from the parent tree. Which is just the right thing for the seeds to use as a source of nutrients and moisture as they germinate. So it's likely to take some 'creative' effort to grow an apple tree from seed even if you have a species that'll breed true. SteveBaker 03:44, 26 March 2007 (UTC)[reply]

It is very likley that an animal would eat the seed. Ants and birds would eat it if they had the chance. Only a few seeds will ever sprout. GB 09:16, 26 March 2007 (UTC)[reply]

Expanding on Saintrain above, if apples are like oranges (bad analogy? :) ) the hardiest rootstock has crappy fruit. So good fruit cuttings are grafted to the hardy root stock. Where I live, you can buy citrus but it's all grafts to a common, hardy rootstock. Fruit trees that grow from the fruit will generally not survive in the soil because of insects and other things that make it inhospitable. --Tbeatty 06:45, 27 March 2007 (UTC)[reply]

Charges of cations/anions influencing chemical behaviour?

Going over observations of reactions between cations and anions, I noticed there was indeed a loose pattern among ions of the same charges, such as 2- ions exhibiting somewhat similar reactions with cations and the 1- ions reacted in a pattern also, but different from the 2- ions. I'm just wondering if it is possible that the charges of the ions play a role in how they react with anions and how big of an influence it has if there is any.

For reference, the anions tested were: SO4 (sulfate), CO3(carbonate), Cl(chlorine), and I(iodide). Sodium sulfate, sodium carbonate, sodium chloride, and sodium iodide are tested separately with barium nitrate, then nitric acid is added to the result. Then silver nitrate is added to fresh samples of the anions, then nitric acid is added to the result. And finally, silver nitrate is added to fresh samples of the anions (similar to before), but ammonia is added instead of nitric acid.

My speculation of the influences of charges on ion reaction behavior arose from looking over the observations of the reactions above. 75.2.147.8 19:29, 25 March 2007 (UTC)[reply]

What happens in your case is often due to an insoluable salt being formed from the anion and cation. The reactions with the acid (nitric acid) affect the anions that have a weak acid - eg carbonate - in this case it also forms a gas. So why is barium carbonate and barium sulphate, and silver halides insoluable? It will be due to the energy of forming the salt compared witht he energy of having the ions hydrated in a water solution. The size of the ion is important too. and in the case of silver the presence of extra orbitals for the ammonia to attach to makes it respond differently to barium. GB 09:26, 26 March 2007 (UTC)[reply]

Occupational Statistics

How would I be able to find out the total number of doctors, medical students, nurses, and etc. in countries? Thank you. Cduffner 20:43, 25 March 2007 (UTC)[reply]

Geckoes of the Kalahari

I published a work entitled "Amphibians and Reptiles of Botswana" in Gaborone in 1987. It was linked to Britannica online- I don't know if it still is. Since I have been living out or garbage-cans (which I call dust-bins) since I graduated from the University of Oxford in November 1990 (in absentia), I have not had much research opportunity.

I was reminded today of a gecko, "eyes of iron", I believe, and forgot which taxon it was designated by myself. I think Homopholis wahlbergi. This raised several nagging questions- one, the genus of the gecko found by a Frenchman reportedly from Lake Ngami, which I reported on in the above publication.

Since I cannot even afford regular warm meals (probably Ivy League graduates can), I have little of my own data available. This internet link was sponsored by Aeqion.de, Joel Klink, Bertheaustr. 4, Goettingen.

Sincerely,

R. D. Auerbach, herpetologist

M.Sc. Oxon.

Former Freedom-fighter,

A. N. C. (then under O. Tambo).

P.S. I am more interested in the possibility of harnessing the protein b12 to a C.V.F. homologue to hunt varmints through the complement cascade-system, a fantastic product of my idiocy.

Sorry to hear about your financial trouble. Perhaps you could authorize a reprint of your book ? According to this site only 1200 copies were printed and they now sell for some $250 each, so you could certainly justify a reprint: [4]. Now, what was your actual question ? Did you want to know about Homopholis wahlbergi ? According to this site it's common name is Wahlberg's Velvet Gecko/African Velvet Gecko: [5]. StuRat 02:01, 26 March 2007 (UTC)[reply]

Popcorn

Can someone either please explain to me what I am interpreting wrong or how is this possible: I just saw on my "Natural taste microwavable popping popcorn" that: per 33g or 1/3 of a bag (there are around 10 bags in this package), there is 160 calories. This means that in one of these bags (which after the microwave produce enough popcorn to fill around one "big cup of popcorn in theaters") there is 480g!? From what I know, which is confirmed in popcorn, popcorn is supposed to have low calories. Can someone please clarify this for me. 65.95.22.227 23:38, 25 March 2007 (UTC)[reply]

I assume you meant to say "there is 480cal!?".

I have here a bag of "Pop·Secret® Premium Popcorn", with "Movie Theater Butter". One bag is 99g, so we're talking about the same size bag, although this brand's 1/3 bag serving boasts 180 calories.

The clue is in the "Movie Theater Butter" part. The next line in the Nutrition Facts box says "Calories from Fat 110", and I don't think there's much fat in popcorn. So it's looking like at least 60% of the calories (and probably more) are just from the butter.

In case you didn't know: popcorn is mostly a substrate. :-) --Steve Summit (talk) 00:53, 26 March 2007 (UTC)[reply]

Popcorn is quite healthy and low calorie when plain, but can be horrid once they soak it with saturated fat and salt. Rather than buying those microwave packets, buy plain popcorn kernels and get a $20 air popper. You can then add butter and salt to taste, and hopefully keep the amount reasonable. Another bonus is that the cost is lower and the popcorn is also less likely to burn. StuRat 01:47, 26 March 2007 (UTC)[reply]

Popcorn is horrid when soaked with fat and salt? Excuse me, but I would rather have my popcorn soaked in fat and salt over plain popcorn. Do you know how that tastes? It tastes like cardboard! And popcorn grown for the purpose of tasting the actual corn instead of the butter and salt, is not much better either. I can't resist, but: popcorn is one of the least healthy things a starving man could eat, over something toxic. [Mαc Δαvιs] (How's my driving?) ❖ 07:05, 26 March 2007 (UTC)[reply]

StuRat's sentence implies that popcorn soaked in fat and salt is nutritionally horrid, not that it tastes horrid. Personally, I've gotten used to a low-fat, low-salt diet, and air-popped popcorn with no added salt or fat at all has grown to taste pretty good to me. It is possible to grow to like it. MrRedact 07:32, 26 March 2007 (UTC)[reply]

Air popped with a little sugar and salt is relatively healthier, although I'm not a fan of mixing sugar and salt. I'd rather have the bad buttery popcorn. --Wirbelwindヴィルヴェルヴィント (talk) 07:48, 26 March 2007 (UTC)[reply]

For those who need to limit sodium but aren't worried about sugar, fat, and calories, caramel popcorn is a good option. Be sure to brush those teeth afterwards, though, as that's a recipe for tooth decay. StuRat 15:25, 26 March 2007 (UTC)[reply]

Or try a healthy dose of raw broccoli, which has a crunchy delicious texture! Nimur 07:31, 27 March 2007 (UTC)[reply]