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| Author |
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| 25 new of 98 responses total. |
keesan
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response 64 of 98:
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Feb 4 13:33 UTC 2000 |
I did a search on 'eye color' with AltaVista. From the first source:
Reliable Answers on Eye Color by the MIT Guy 1
By JJ Brannon
[1]jjbrannon@aol.com
_________________________________________________________________
I was a student of Salvador Luria [Nobel Laureate for Genetics] at MIT.
Two brown-eyed parents can easily have a blue eyed child.
Two completely blue-eyed parents CANNOT have a fully brown-eyed child with
normal eye development except in certain extremely rare circumstances.
The gene for brown/blue eyes is EYCL3 found on Chromosome 15.
The gene for green/blue eyes is EYCL1 found on Chromosome 19.
Brown is the result of melanin deposits in the iris.
Green is the result of [this is debated] lipochrome deposits in the iris.
Blue-grey [and in some albinism, pink] is due to a lack of pigment in the iris
.
The underlayer, called the stroma, reflects light through its cells like
a mirror's silver back. How the pigment is distributed over the iris involves
other genes which produce flecks, rays, rings, partial diffusion or
full diffusion. This inheritance is very complicated and the genes have not
been well identified.
Here are some reliable sources:
http://www.ncbi.nlm.nih.gov/htbin-post/Omim/dispmim?227220
http://www.ncbi.nlm.nih.gov/htbin-post/Omim/dispmim?227240
http://www.gdb.org/gdb-bin/genera/genera/hgd/ObjectName/2662023?!sub=0
Francis Galton -- Davenport & Davenport -- Bryn & Winge -- Lenz -- Hughs
as discussed in
Human Genetics, Chapter 5, by Reginald Ruggles Gate [1952]
Heredity & Your Life, pp. 286-312, Boyd [1950]
_________________________________________________________________
References
1. mailto:jjbrannon@aol.com
2. http://sln2.fi.edu/tfi/units/life/forums/anatomy/anatomy.html
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prp
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response 65 of 98:
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Feb 4 20:16 UTC 2000 |
I was reading about the Apple Airport. It said among other things that
the card had a power output of x.x dBm. What is a dBm?
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russ
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response 66 of 98:
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Feb 4 22:54 UTC 2000 |
dBm is decibels relative to a milliwatt. 10 milliwatts = +10 dBm.
One microwatt = -30 dBm. (Decibels are a logarithmic scale, 10 dB
is a factor of ten. One dB is about 1.26.)
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rcurl
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response 67 of 98:
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Feb 5 05:17 UTC 2000 |
i.e., dB = 10*log(P2/P1), where log is base 10 and P2 and P1 are
two *powers* that you want to relate. A useful value to remember is
3 dB = close to a power ratio of 2. Some people try to apply dB to
voltage or current, but then one has to use dB = 20*log (E2/E1).
A related (and commonly used in control theory) terms is the dL -
the decilog, which is simply dL = 10*log(X2/X1) are two similar
quantities whose ratio you want to express over a large range.
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oddie
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response 68 of 98:
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Feb 7 05:10 UTC 2000 |
resp:64
Thank you very much Keesan. I will also have a look at those sources.
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prp
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response 69 of 98:
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Feb 7 19:55 UTC 2000 |
Ah, now if it had been dBmW, I might have had a chance of figuring
it out.
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russ
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response 70 of 98:
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Feb 8 03:50 UTC 2000 |
Every profession has its shorthand. dBm is almost certainly in lots
of glossaries, so if you'd looked you probably would have found it.
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rcurl
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response 71 of 98:
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Feb 8 05:34 UTC 2000 |
I think it is easier to ask in a conference devoted to such things.
Isn't that one of the purposes they serve?
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russ
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response 72 of 98:
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Feb 9 03:03 UTC 2000 |
Never said it wasn't, but learning to RTFM is also important.
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rcurl
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response 73 of 98:
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Feb 9 06:45 UTC 2000 |
That requires having the FM.
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keesan
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response 74 of 98:
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Oct 29 22:22 UTC 2000 |
What happens to oil (alkyd) paint at 30 degrees F, if anything? (Jim left
our primer out last night, sitting on a warmed concrete slab, so it may not
have gone quite to freezing). Why should you not apply it below 45 degrees?
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rcurl
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response 75 of 98:
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Oct 29 22:56 UTC 2000 |
It doesn't cure rapidly, meanwhile picking up dust (and leaves).
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keesan
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response 76 of 98:
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Oct 30 17:18 UTC 2000 |
We will not worry then, as the porch warms up rapidly the next morning and
these boards are only being painted to act as a vapor barrier, and the plastic
on the porch should keep out the dust and leaves.
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oddie
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response 77 of 98:
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Nov 25 07:21 UTC 2000 |
This was asked in the agora item on candy, retailing and suchlike, but
to prevent drift I'll repeat it here:
Why are saturated fats solid but unsaturated fats liquid (in general)?
My recollection from chem class is that dispersion forces are greater
for some reason in straight carbon chains, but I haven't a chemistry
book on hand at the moment so I can't check this.
On a possibly related note, what happens to butter when one melts it
and then allows it to cool again? It changes color and texture, but
why, chemically?
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keesan
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response 78 of 98:
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Nov 25 18:38 UTC 2000 |
Heating butter and cooling it separates a layer of fat (on top) from a layer
of other things that dissolve in water and reflect more light. The top layer
is what Indians call ghee. It is less likely to burn than the dissolved or
suspended matter, and it keeps longer since many microorganisms cannot live
in pure fat (they need water and minerals and oxygen, which is blocked by the
fat). One method of preserving foods is to pour melted lard or butter or
olive oil into the top of the jar of hot food. You can bake the whole thing
in the oven for a while to sterilize it.
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rcurl
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response 79 of 98:
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Nov 27 06:42 UTC 2000 |
Unsaturated fats have a lower melting point than saturated fats, in
general, for the same carbon number. Yes, it is because the dispersion
forces are greater for the saturated fats. A mechanical way to look at it
is that the rigidity of the double bonded carbons, which also introduces a
"kink" into the fatty acid, interfers with alignment of the molecules and
hence with crystallization.
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oddie
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response 80 of 98:
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Dec 3 07:16 UTC 2000 |
Thank you both.
I had heard of ghee but never knew what it really was. Today I looked up
hydrocarbons in my chemistry textbook (by someone called Steven Zumdahl,
if anyone's interested) but didn't find anything on b.p. and m.p. (I
suspect I overlooked it, but as I know the answer in about as much detail
as the book would probably give it hardly matters). Thanks again.
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rcurl
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response 81 of 98:
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Dec 3 21:55 UTC 2000 |
You probably didn't overlook it - elementary texts usually don't get
into the physics of phase changes except to note they occur, and maybe
some values as melting point is used to identify compounds.
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keesan
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response 82 of 98:
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Dec 3 22:15 UTC 2000 |
The best ghee is said to come from water buffaloes. Water buffaloes are also
found in Kosovo, where there are flat wet areas, and a fermented clotted cream
is made from the milk. I don't know how the war affected the animals.
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dannyboy
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response 83 of 98:
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Nov 8 13:26 UTC 2001 |
As for why saturated fats are generally solid, as opposed to unsaturated ones,
it is basically to do with the shape of them. The straight chain alkanes can
sit together more closely, resulting in higher Van-Der Vaals forces
(instantaneous dipole-induced dipole). There may also be hydrogen bonding
effects which are influenced by the double bonds.
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keesan
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response 84 of 98:
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Feb 3 03:44 UTC 2003 |
Jim asks if ozone can pass through steel, as in refrigerator motors. He heard
that hydrogen can pass through steel.
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rcurl
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response 85 of 98:
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Feb 3 07:33 UTC 2003 |
No, ozone cannot pass through steel. Why? There isn't much ozone around.
Yes, hydrogen has dissolve in steel - leading to embrittlement.
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gull
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response 86 of 98:
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Feb 3 15:46 UTC 2003 |
Most motors are vented to get rid of heat, though, so ozone can escape
that way if there's any arcing going on.
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russ
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response 87 of 98:
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Feb 3 22:40 UTC 2003 |
The question in #84 betrays two misconceptions:
1.) There's no ozone in a refrigerator's cooling system.
Refrigerator motors are induction motors, which cannot create
ozone. The commutator sparking of brush-type motors makes
ozone; induction motors have no commutators or brushes.
2.) The creation of ozone requires free oxygen. There is
essentially no oxygen in a refrigerator's system.
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rcurl
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response 88 of 98:
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Feb 4 07:13 UTC 2003 |
3.) ozone is very reactive and would have been depleted by reaction
first IF any could have been formed.
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