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<div class="moz-cite-prefix">On 18/09/2012 16:05, John Clark wrote:<br>
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<div>True, all the information on how to make an egg is there in
the scrambled eggs but that does no good because I don't think
even Nanotechnology can get that information out and figure
out how to unscramble an egg. The egg has undergone turbulence
and that means tiny changes in initial conditions have led to
huge changes in outcome, we don't want that happening to
brains. So the big question is, does the brain preservation
method cause turbulence? I could very well be wrong because
I'm no expert but my intuition says that plastic infusion is
less likely to produce turbulence than freezing. <br>
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<br>
I understand what you mean, although turbulence is probably not the
best word here. What sensitive dependence on initial conditions
(chaos) does is to make noise more powerful, randomizing parts of a
system. Noise that just moves the system away from the original
state is not a problem itself. The problem is the noise that makes
it uncertain which original state the system had.<br>
<br>
What kind of noise do we expect to see in freezing or plastination?
In both there is the noise from dying. In freezing there is
biochemical change and physical change due to the freezing process,
in preservation there is the same due to the fixation, and then some
chemical reactions during storage. <br>
<ul>
<li>Freezing did cause a mess due to crystal formation and
cracking, and is still mechanically a bit nasty, but I don't
think (cryo-gurus please chime in) it causes regions to
scramble. They just turn to puzzles. </li>
<li>The biochemical changes of both processes are hard to judge,
but this is where I would be most worried: the brain is
dependent on a lot of biochemical states that might only partly
survive either treatment. This is where I really would like to
know how much happens in a synapse, in particular to whether
receptors remain bound to membranes and what G proteins do. </li>
<li>In freezing mobility of stuff goes down a lot quickly, while I
get the impression the fixation is a bit slower. Then there is
the problem of chemical change in fixed tissue: again I don't
know if anything diffuses much, but that is worth watching for.
</li>
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Not sure what the take home message is, beyond more research is
needed (or, if it has been done, more dissemination needed). <br>
<br>
<pre class="moz-signature" cols="72">--
Anders Sandberg,
Future of Humanity Institute
Oxford Martin School
Faculty of Philosophy
Oxford University </pre>
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