Wikipedia:Reference desk/Archives/Science/2008 February 28

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February 28

Chemistry: vapor and ideal gas

Hi! I'm wondering why once you have a vapor which near condensation point, why it doesn't behave like an ideal gas. I recently learned about what an ideal gas is. But I'm just wondering why when it liquifies it doesn't behave like an ideal gas (like PV = nRT). Thanks! —Preceding unsigned comment added by 69.4.130.179 (talk) 08:32, 28 February 2008 (UTC)

The ideal gas model assumes that the gas molecules don't interact with each other. In a real gas close to its condensation point the molecules interact strongly. --71.146.162.148 (talk) 08:52, 28 February 2008 (UTC)

The van der Waals equation is useful for describing a vapor near its condensation point. It takes two parameters, representing the volume of the molecules (which would be zero for an ideal gas) and the attraction between molecules. Icek (talk) 12:23, 28 February 2008 (UTC)

algae

What is a good surface for algae (like from my fresh water fish tank) to grow on and what things could i do to help algae to grow faster.

thanks —Preceding unsigned comment added by 76.236.187.176 (talk) 01:21, 28 February 2008 (UTC)

are your fish algae eaters, because usually the growth is undesirable. Wisdom89 _{(T / ^C)} 02:15, 28 February 2008 (UTC)

Sunlight is of course needed for algae. I would suspect rough surfaces like rocks would help, also you need algae! There needs to be some algae present to start with. I think if you go to a pond/lake/rive etc and get some rocks/gravel and put that in the tank it would help growth a lot...--Shniken1 (talk) 03:15, 28 February 2008 (UTC)

Alga will grow on virtually any solid surface, witness many glass aquariums. More light and more nitrogenous matter in the water and you'll be up to your knees in no time. Richard Avery (talk) 08:42, 28 February 2008 (UTC)

It will grow almost anywhere, if you have tropical fish with warm water especially. Such a pain to remove it. (slightly off topic - Does anyone know of a product that could remove it without killing the fish?) TheGreatZorko (talk) 11:47, 28 February 2008 (UTC)

two methods - remove the nutrients, or use an algicide - both product exist. search for "algae control aquarium" or similar —Preceding unsigned comment added by 87.102.84.112 (talk) 11:55, 28 February 2008 (UTC)

There is a biological variation - add an algae eating fish/snail/shrimp + add plants to compete with the algae for nutrients NOTE the plants must not be edible by the fish/animals as this will just compound the problem..87.102.84.112 (talk) 12:32, 28 February 2008 (UTC)

Duckweed (or similar) works - it grows fast on the surface, removes nutrients, and cuts out light to below the water surface. There probably are many other ways..87.102.84.112 (talk) 12:32, 28 February 2008 (UTC)

Commercially available magnetic glass scrubbers are pretty effective for the tank walls. Nimur (talk) 18:22, 28 February 2008 (UTC)

Hi. To grow algae maybe cause global warming and then add water. Thanks. ~AH1^(TCU) 22:45, 28 February 2008 (UTC)

In the past I have periodically used an ion exchange resin pouch to remove nitrate. Use a nitrate test kit to quantify the quality of nitrate in the water. William Avery (talk) 13:04, 4 March 2008 (UTC)

decibel levels of human screaming

What is the range of decibels when human beings scream? This is regarding the section stub at the article Screaming, is there any data on pitch?Cholga^talK! 04:14, 28 February 2008 (UTC)

Sharapova? at 101.2 decibels [1] Julia Rossi (talk) 07:53, 28 February 2008 (UTC)

Alan Myatt - 112.8 DECIBELS. Clarityfiend (talk) —Preceding comment was added at 09:13, 28 February 2008 (UTC)

My mother-in-law, when she first met our kitchen mouse, surely has to break all records (and a few window panes)! Sandman30s (talk) 12:55, 28 February 2008 (UTC)

Robert Graves wrote a short novel called The Shout, which puts all other claims in the shade. The premise was that there was a man who could kill people just by the volume of his shout. -- JackofOz (talk) 22:27, 28 February 2008 (UTC)

In Günter Grass's book (Nobel price in litterature) die Blechtrommel the hero manage to break all the windows of Danzig by screaming. —Preceding unsigned comment added by 216.195.17.16 (talk) 03:19, 29 February 2008 (UTC)

Hi. A few years ago I saw on TV (forgot what show it is) about a Japanese contest or something like that, where contestants scream as loud as possible. I think one pan recorded a very high figure, not sure what it was exactly, but probably between 120 - 160 decibels. Also when I scream or yell it frequently reaches (my estimate) maybe 90 decibels at 2 metre distance :P . Hope this helps. Thanks. ~AH1^(TCU) 22:40, 28 February 2008 (UTC)

A quick googling finds some poor kids' mum screaming at 129 dB. Doesn't look terribly scientific though. Weregerbil (talk) 10:02, 29 February 2008 (UTC)

determination of urea

Give the report on how urea can be determined quatitatively using the diacetyl monoxime method —Preceding unsigned comment added by 82.206.143.13 (talk) 12:57, 28 February 2008 (UTC)

Hi. This question sounds very much as if it is a homework question - something which the reference desk will not answer. If you try it and tell us where you get stuck, then we can help. -mattbuck (Talk) 13:25, 28 February 2008 (UTC)

Search for "diacetyl monoxime method" using Wikipedia's search box and you'll get some useful results. --Bowlhover (talk) 13:29, 28 February 2008 (UTC)

Osteo-Odonto-Keratoprosthesis

Osteo-Odonto-Keratoprosthesis ???? any ideas —Preceding unsigned comment added by 12.171.224.124 (talk) 15:32, 28 February 2008 (UTC)

A keratoprosthesis is an artificial cornea. Osteo = bone; odonto = tooth. I can't imagine why one would make a bone-tooth-cornea-prosthesis, except as conceptual art. - Nunh-huh 17:12, 28 February 2008 (UTC)

After a bit of research, it appears that it is a type of prosthetic lens cornea which is surrounded by a thin layer of the patient's own bone (specifically, a tooth). This is done in cases where graft rejection has previously occurred, since having your own bone tissue surrounding the prosthetic lens cornea reduces its antigenicity. If you're looking at getting this procedure done, you should probably consult a physician/surgeon: despite it being a 40 year old concept, it's still considered "experimental". Here is a recent (2001) review by the UK NHS: [2]. (EhJJ)^TALK 17:28, 28 February 2008 (UTC)

And a news story about its use [3] Bazza (talk) 13:08, 29 February 2008 (UTC)

Mutation notation

From some article "mutant constructs encoding the I81_V85del, M266fsX4 and R325X SPRED1 proteins" - I understand the last notation - amino acid R replaced by X at position 325 but I'm less certain about the first two. A little help? —Preceding unsigned comment added by 145.29.21.165 (talk) 15:38, 28 February 2008 (UTC)

I may be mistaken, but my educated guess is "I81_V85del" is a deletion from I81 to V85. "M266fsX4" has something to do with a frameshift. (EhJJ)^TALK 16:58, 28 February 2008 (UTC)

I81_V85del = a deletion (del) from residue 81 (isoleucine) to 85 (valine)

M266fsX4 = a frame shifting change with methionine in position 266 as the first affected amino acid, with the new reading frame ending in a stop codon at position 4.

R325X = mutation resulting in a change from arginine to an undetermined amino acid at position 325.

The discussion of mutation notation here may be helpful to you. - Nunh-huh 17:07, 28 February 2008 (UTC)

(ec) I assume the article is this one, which contains some expanded information: We identified seven different mutations in SPRED1: three nonsense mutations (leading to R64X, K322X and R325X), two frameshift mutations (leading to M266fsX4 and S383fsX21), one missense mutation (leading to S149N) and one in-frame deletion (leading to I81_V85del). Recommended nomenclature for mutations can be looked up here. I81_V85del does indeed mean that amino acids 81 (which was an isoleucine, I) through 85 (which was a valine, V) have been deleted. M266fsX4 means a frame shift mutation that scrambles the meaning of amino acids 266 (which was a methionine, M) onwards, and creating a stop codon 4 amino acids later; the protein product thus has 265 correct amino acids followed by 4 nonsense amino acids. The notation R325X is called a nonsense mutation, but effectively means that amino acid 325 (which was an arginine, R) has been replaced by a stop codon, which causes the protein product to be truncated at this position. (Note that this is different from Nunh-huh's answer above.) --mglg_(talk) 17:19, 28 February 2008 (UTC)

Misunderstood

How can it possibly be true that there is no such insect as a spider??? —Preceding unsigned comment added by 79.122.82.130 (talk) 16:41, 28 February 2008 (UTC)

Spiders are arachnids (Class Arachnida), not insects (Class Insecta). They both belong, however, to the Phylum Arthropoda--the joint-legged animals. Insects have three body parts and six legs, while spiders have two body parts and eight legs.--Eriastrum (talk) 16:47, 28 February 2008 (UTC)

Looking for a name of

an insect (or not) that looks like a bunch of white fibers or white hair. Size is about 1 or 2 cm. —Preceding unsigned comment added by 89.0.140.163 (talk) 14:24, 28 February 2008 (UTC)

Mealybug?--Eriastrum (talk) 16:43, 28 February 2008 (UTC)

The larvae (caterpillars) of some moths are covered with white hairs. For example, the flannel moth caterpiller [4], which has stinging hairs--so watch out! Some of the wooly bear caterpillars have white hairs as well. These are in the families Megalopygidae and Arctiidae.--Eriastrum (talk) 19:21, 28 February 2008 (UTC)

No. Sorry. Look at the picture. —Preceding unsigned comment added by 89.0.52.106 (talk) 12:28, 29 February 2008 (UTC)

Looking for a name of a creature

Looks exactly like this seed without the long 'tail'

I'm looking for a name of an insect / a spider or any other from of life that looks like a bunch of white fibers. It's size is about 1-2 cm. It looks a very primitive form of life So I don't think it is a spider or an insect. It's structure resembles a spider. When you put something next to it, it will jump on it. I saw two of it on my room today.—Preceding unsigned comment added by 89.0.140.163 (talk • contribs)

if this is NOT your questino why would you change the title and add your question instead of creating a new one —Preceding unsigned comment added by 79.122.82.130 (talk) 19:56, 28 February 2008 (UTC)

Done. What is it?—Preceding unsigned comment added by 89.0.140.163 (talk • contribs)

Down feather next to grain of sand.

Do you have any pet birds? My parrot produces a lot of little down feathers (as seen on right) that look like that and often stick to things due to their static charge.(EhJJ)^TALK 22:10, 28 February 2008 (UTC)

Are you sure it's a spider? I've noticed some very light white spiderlike fluff sometimes on my kacket or outside. Could be perhaps some type of seed or jacket feather. It will float up in the air if I put it over the rectangular furnace home heating vent. It flies with a small wave of air. However if it is a spider and does move with absoludely no air currents, then please do not touch it or it may bite. However if it has more than eight legs it's most likely not a spider. Hope this helps. Thanks. ~AH1^(TCU) 22:33, 28 February 2008 (UTC)

It doesn't look like a feather and I have no birds at home. I'm pretty sure it's not a spider. Maybe it's a seed. But it reacts to motions... —Preceding unsigned comment added by 89.0.52.106 (talk) 12:24, 29 February 2008 (UTC)

Hmmm you live in Israel so I guess you don't use a feather/down duvet either? I had something similar, I was trying to work out what the heck it was, it seemed to be living based on the way it was moving but eventually I realised it was probably just a piece of down or feather from my duvet that was moving in the wind Nil Einne (talk) 12:52, 29 February 2008 (UTC)

Just in case, have a look at the jumping spider link, [[5]] they can be very small. Richard Avery (talk) 18:57, 29 February 2008 (UTC)

Maths\Geometry\Thaumaturgic triangle

What is understood under a Thaumaturgic triangle? Is is more a theosophy and/or a Math issue? example

Thanks and greez, 88.64.94.148 (talk) 17:11, 28 February 2008 (UTC)

Yes, it's mysticism, not math. The thaumaturgic triangle is a triangle inscribed inside a circle. It is said by some modern-day witches to be used in demon-summoning ceremonies, and is given many innovative interpretations.. - Nunh-huh 17:17, 28 February 2008 (UTC)

We have articles on thaumaturgy and triangles. Historically, a lot of believers in the occult have placed high significance on geometric shapes for reasons that never really made much sense to me. Nimur (talk) 18:18, 28 February 2008 (UTC)

Eggs

Oh, and one final tip that most people don't know; if you want silky smooth scrambled eggs, that are suprememly tender, after mixing your eggs with whatever you are going to mix them with, pour them trough a fine-mesh wire strainer to remove the little protien strings found in the egg. What exactly are those filthy protein strings? --Seans Potato Business 21:18, 28 February 2008 (UTC)

They are probably referring to the chalaza -- 128.104.112.47 (talk) 22:41, 28 February 2008 (UTC)

Identify this bird?

Hi. Sometimes I notice this bird's song, especially in the warmer months. What brought me to attention was that today I noticed this bird singing for a few minutes this morning (at -20C temperatures!). Its song is a rather high-pitched and singsong "wree-oou" or sometimes "wroou-WHEE" and occasionally chirping. In sping and summer I've noticed these birds singing to each other. I know this bird only by song but I think I might have seen it but I'm not sure. I live in southern Ontario. Any ideas what bird this might be? Thanks. ~AH1^(TCU) 22:16, 28 February 2008 (UTC)

While my crap work internet wont let me look at any of my birding sites I do know that the boreal forest areas of Ontario see about 300 different species of bird throughout the year. So without a bit more info it is going to be a tough call. Do you happen to remember where the bird likes to spend its time (trees, bushes, grassy areas)? That would help to narrow it down :) 161.222.160.8 (talk) 23:08, 28 February 2008 (UTC)

(ec) Hi right back atcha. You aren't giving us much to go on, I guess you know. Is the phrase repeated? How many times? Is it loud? Does it seem to be coming from up in a tree or down on the ground or where? Can you decribe the vocal quality—flute-like, raspy, hoarse, liquid, wheezy, etc.? Our article Bird vocalization is worth a look, especially "Identification and systematics", and there are some common bird calls free at Cornell. --Milkbreath (talk) 23:10, 28 February 2008 (UTC)

Hi. I'm guessing it maybe in tree because I said so (and where else could it go, other than maybe the metal-cold power lines or perhaps a bush/hedge on a snow-covered cold winter's morning)? I live in an urban area but there are lots of bushes and forests and fields nearby. I've seen hundreds of sparrows in the trees and feeding on seed in and near trees, bushes, and rooftops in winter, but if I remember correctly the sparrows I see usually chirp and have markings on their chest but I don't really think this is a sparrow. Its song sounds very singsong, and sort of flutelike I guess. With the wree-oou the first note is higher in the second, and I think the second note is usually longer than the first. I'm guessing the two notes together last maybe 1-2 seconds. It repeats on a predictable basis until it stops and/or flies away, maybe once every 5-15 seconds. I'm not sure but I think I remember when they sing to each other it sounds like: "Wroou-wree? Wree-woou! ... whroou-wree? Wree-woou!" I'm thinking from maybe 10-80 m away it is maybe 20-50 decibels. I heard this today shortly after sunrise, and it was a clear, bright, sunny day, but very cold (wind chill -27C!). I think on warmer days I've heard it maybe a few hours after sunrise on mainly sunny mornings. If you're wondering which one of the 5 great lakes I live nearest to when I heard this, probably Lake Ontario. I heard it this morning around 7am (local time). I tried looking through a bird identification book for eastern North America but I'm still not sure what it is. Any ideas? Thanks. ~AH1^(TCU) 23:36, 28 February 2008 (UTC)

Thanks. I'm looking at the Black-capped Chickadee. The song is in the article under "Vocalization". It's two notes, first note higher, monotonously repeated, clear, and loud. If that ain't it, we can try again. --Milkbreath (talk) 00:00, 29 February 2008 (UTC)

Hi. I can't really download the song right now but the descriptions seem just about right. So I think this might be the one I'm looking for. Nayway I'm also finding http://identify.whatbird.com quite helpful and faster than any book (but it appears to be on the blacklist page for some reason) although it wouldn't be good for identifying it if I only know its song. Thanks. ~AH1^(TCU) 01:24, 29 February 2008 (UTC)

Hi. This morning I heard the bird again at around 7 in the morning. Again, it was mainly clear except for some cirrostratus clouds near where the sun rose, blocking out the sun for a minute. I think the call was close to one second long. I also heard a crow-like call, as if they were calling to each other, one higher and one lower. One had 5 caws and the other one 4, I don't remember which was which. I also heard a similar call to the one in interest, except it sounds like the first note only, but cut short. I may have also heard some brief chirping after that. The 9 caws in total were about 3 seconds long. One similarity about this time to last time was that it was at 7 in the morning, the day before a winter storm. This time it was -10C outside. Thanks. ~AH1^(TCU) 16:34, 2 March 2008 (UTC)

It sounds like you're hearing several different species of bird. The only thing that goes caw is a crow. A one-note song is a rarity, and makes me think blue jay messing around. Neither of those chirps. Birds of different species do not respond to each other's songs vocally. Of course, it could be a mockingbird making all those noises, but it seems a tad cold for him, and they like to be seen, flashing their wings on the ground and perching in the open to sing. Have you listened to any of the bird noises I pointed to? They would be good for comparison, like "sounds a little like this one, but weaker", or whatever. --Milkbreath (talk) 20:56, 2 March 2008 (UTC)

Jays are also mimics—not quite as good as mockingbirds, but they can make all sorts of odd noises. -- Coneslayer (talk) 16:33, 3 March 2008 (UTC)

Hi. I listened to the song here, and I think that sounds exactly like the one I heard, but I thought that the one I heard had perhaps a slightly longer interval between the calls, and that it hurt my head less than the song I played. Only the first 10 seconds or so (of the learnbirdsongs website, not the one on Wikipedia which I couldn't download) actually sounded like what I heard, although I might have heard the latter sounds in summer. Thanks. ~AH1^(TCU) 22:32, 3 March 2008 (UTC)