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Richard Clark wrote:
On Wed, 20 Aug 2008 10:23:11 -0700, Jim Lux wrote: The very last study, on the very last page with the second paragraph offers: "For an effectively transmitted power of 0.25 W, the maximum averaged SAR values in both cubic and arbitrary-shaped volumes are, respectively, about 1.72 and 2.55 W kg-1 for 1g and 0.98 and 1.73 W kg-1 for 10 g of tissue." The last study gives us more exposure data (the discussion of which inevitably scatters in the rhetorical wind of debate). I can only wonder if the reader can draw a conclusion from this quoted sentence that can be expressed in temperature rise. There's enough data to do this, only intelligence remains to perform. that's pretty simple.. Assume that the tissue has the specific heat of water. 1 Joule will raise the temperature of 1 gram of water about 1/4 degree C.. That's a rise of 0.015 degree/second, or 10 degrees in 10 minutes. In reality, you won't see that much rise, because bloodflow carries some of the heat away, and so does convection. Thanx Jim. Exactly. If this proves anything, it proves that those who are not worried about stepping out into the sun, but fear exposure to their cell phone, they will always be worried about their cell phones. Actually, it's not quite *that* simple.. The simple analysis is just for thermal effects. One has to also ask whether there are significant "athermal" effects. These can come from several potential sources. First, one can consider whether the radiation itself can do anything.. well, the photon energy at microwave frequencies is so low that it's orders of magnitude below any known chemical reaction's activation energy. Or, one can consider E or H field effects. If the E field is high enough, it can depolarize a neural membrane, for instance, and cause false neural impulses. That would be an acute effect. One also needs to consider peak vs average effects. One could probably power a defibrillator from a cellphone battery quite nicely, and that can dump a few hundred joules at just the right time to cause some serious problems. Again, though, that's an acute, not exposure/chronic effect. |
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