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Grex > Agora41 > #144: First second-hand smoke, now second-hand cellphone? | |
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gull
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First second-hand smoke, now second-hand cellphone?
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May 2 14:06 UTC 2002 |
A Japanese researcher got curious about the electromagnetic radiation caused
by cell phone users inside commuter train cars, and has calculated that it
could exceed safe exposure guidelines. Interesting theory, but I'd like to
see it backed up with some actual field strength measurements. It may
actualy vary quite a bit from moment to moment, since a cell phone adjusts
its power output based on signal strength.
http://www.newscientist.com/news/news.jsp?id=ns99992238
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| 38 responses total. |
rcurl
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response 1 of 38:
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May 2 15:22 UTC 2002 |
Based on *received* signal strength? Then it would boost its power up
to high in a metal train car, which partially shields the phone from
the tower. It would also not be as simple as the article tends to make
it, as there would be radio "hot" and "cold" spots in the car.
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gull
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response 2 of 38:
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May 2 16:15 UTC 2002 |
Not necessarily. I get higher signal strength inside my metal car than I do
in the middle of the concrete office building I work in.
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rcurl
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response 3 of 38:
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May 2 18:01 UTC 2002 |
Concrete buildings are reinforced with steel rods/mesh. Pretty good
Faraday shield. But my statement in #1 applies to #2 as it depends
where you are in both a car or a building.
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bdh3
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response 4 of 38:
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May 4 07:36 UTC 2002 |
re#3: Its called 'rebar'.
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rcurl
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response 5 of 38:
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May 4 15:45 UTC 2002 |
If you want to play contractor....
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bdh3
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response 6 of 38:
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May 6 06:23 UTC 2002 |
Its called 'rebar' in the Home Depot insert in the newspaper - hardly
targeted towards contractors.
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brighn
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response 7 of 38:
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May 6 13:59 UTC 2002 |
Larson used the word "rebar" in a Far Side cartoon. (Two cavemen standing next
to a smoldering chicken-wire frame of a cave, one saying: "Boy, you wiped out,
Kumba...Nothing left but rebar.")
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rcurl
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response 8 of 38:
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May 6 16:06 UTC 2002 |
It started as a contractor term, adopted by everyone as it sounds sexy.
A lot of words come into our vocabulary that way. People like to swing
the lingo as it makes them (they think) sound knowledgeable. Ask them
to describe the types and uses of the many varieties of "rebar" and
they will be struck dumb.
Take a look at what it's called on a professional site
(http://www.asf-rebar.com/charts_specs.htm): "ASTM Standard Reinforcing
Bars".
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scg
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response 9 of 38:
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May 6 18:26 UTC 2002 |
If the purpose of communication is to be understood, using the commonly
understood terminology is helpful. If somebody says rebar maybe it sounds
sexy to you, but to most of us it sounds like metal bars used to reinforce
concrete. If somebody starts talking about ASTM Standard Reinforcing Bars,
chances are the average listener won't have a clue what they're talking about.
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brighn
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response 10 of 38:
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May 6 18:39 UTC 2002 |
#8> Just because a word starts out as professional lingo doesn't mean it needs
to stay that way forever and always.
,
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gull
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response 11 of 38:
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May 6 19:01 UTC 2002 |
Speaking of which, I got to wondering something yesterday. Those swivel
joints on the drive axles of front-wheel-drive cars....why are they called
"constant velocity joints"? What's constant about their velocity?
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rcurl
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response 12 of 38:
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May 7 00:32 UTC 2002 |
They the drive and driven shafts turn at the same velocity (rpm),
independent of the angle between them (within allowable limits).
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mdw
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response 13 of 38:
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May 7 00:35 UTC 2002 |
They used to call them "Universal Joints".
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rcurl
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response 14 of 38:
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May 7 00:45 UTC 2002 |
One still should get it right, then. I referred to "reinforced with steel
rods/mesh". Welded wire mesh is not "rebar", and those in the industry
know that "rerod" is equibalent to "rebar". So what I said was correct
but avoids "jargon". (I've been wondering why I care... 8^} I think
it was because #4 was an ignorant attempt at correction. Oh well....
who cares anyway? It still forms an electromagnetic shield in concrete
buildings.)
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rcurl
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response 15 of 38:
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May 7 00:49 UTC 2002 |
Re #13: a universal joint is NOT a constant velocity joint. See, for example,
http://www.4wdonline.com/A.hints/Universal.html.
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mdw
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response 16 of 38:
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May 7 00:53 UTC 2002 |
Ah - so they're slightly more complicated are they? Interesting...
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rcurl
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response 17 of 38:
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May 7 01:14 UTC 2002 |
It was a little harder finding a diagram of a CV joint. There is a rather
poor one at
http://www.hewett.norfolk.sch.uk/curric/techweb/epscweb/mech1.htm#coupling
The limit would be using a piece of hose as a flexible coupling, but that
is not a very rigid coupling, which is needed for power and force
transmission.
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gull
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response 18 of 38:
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May 7 13:11 UTC 2002 |
Ah, okay, that site clears it up. I hadn't realized that a universal
joint's speed varied through its rotation when it was at an angle.
Universal joints sure are more durable than CVs, though. I found a torn CV
boot on my car recently and my mechanic told me I might as well get the
whole driveaxle replaced, because once the boot is torn the CV is usually
damaged almost immediately from the grease being contaminated. Universal
joints on rear wheel drive cars seem to last the life of the vehicle with no
grease boots at all.
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jp2
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response 19 of 38:
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May 7 13:15 UTC 2002 |
This response has been erased.
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gelinas
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response 20 of 38:
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May 7 14:43 UTC 2002 |
"Old World", "New World", "Third World". "First World" is a back-formation
from "Third World", so there is NO "Second World".
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jp2
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response 21 of 38:
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May 7 14:51 UTC 2002 |
This response has been erased.
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jp2
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response 22 of 38:
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May 7 14:53 UTC 2002 |
This response has been erased.
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flem
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response 23 of 38:
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May 7 16:45 UTC 2002 |
I don't have handy the references, but it's my understanding that #21 is
mostly wrong. In particular, Switzerland would not be considered third world.
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jp2
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response 24 of 38:
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May 7 16:50 UTC 2002 |
This response has been erased.
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