From: Eugene Leitl (eugene.leitl@lrz.uni-muenchen.de)
Date: Mon Feb 28 2000 - 19:18:38 MST
Jim Hart writes:
> "What we have here is a failure to communicate".
"Some men, you just can't reach".
> >(assuming a
> >nondissipative, deterministic physical process despite dramatic
> >evidence to the contrary
>
> Freezing is largely nondissipative. Cracked and displaced
No. Disagree strongly here. Though not having to bear burden of proof,
provided things go as expected I will nevertheless document this
extensively. You can't improve a process if you don't have a quality
metric.
> surfaces, furthermore, leave around a large amount of information
> on matching surfaces, like a jigsaw puzzle. Thus for freezing
I do not regard the cracks a problem at all. Nor do I share this
peculiar specialist blindness.
> damage Merkle's analysis may be too *pessimistic*: we can often use
^^^^^^^^^^^^^^^^
This is a joke, no?
> pattern matching rather than the computationally more expensive
> cryptanalysis/machine learing techniques. Ischemic damage
The cryptoanalysis analogy is btw perfectly valid if you attempt to
reconstruct the real thing by monitoring operation (say, using 10^9
nanoprobes in vivo), especially if including manipulative measures
(exciting subsystems and analyzing their activity dynamics).
It's just that a lot of people will die, perhaps all of us here
present, if we wait for the advent of this technology (if it indeed
arrives, which is far from being guaranteed). Nor is sustainability of
patient storage guaranteed. As in every small market, customer (your)
attitude matters.
> is another matter. It involves quite dissipative chemical
> reactions. There is good reason to believe that freezing
> damaging will be vastly easier to correct than ischemic damage.
Disagree here also. Ischaemic damage is synergistic, however, because
it inhibits or prevents altogether the loading of tissue with
cryoprotectants. Such a small issue, eh?
If you thought that typical cryonics patients look bad, don't even try
to look at straight freeze. Ugh.
> The good news is that hypothermic conditions, for example
> hypothermic surgery, have been observed to prevent ischemia
> for hours at a time. Unfortuneately good hypothermic
Yes, there are magic drugs, and there are advanced methods (partial
liquid ventilation with fluorocarbons, which uses the lung as
efficient heat exchanger allowing cooling rates better than invasive
measures like peritoneal lavage).
Such new drugs and novel methods are not widely deployed in medical
practice, and will not be used on patients considered hopeless or
already dead. Suspensions under controlled conditions are _not_ the
norm. Your stainless steel bracelet does not guarantee salvation.
> conditions are often absent. Prevention of ischemic damage
> needs much further study and higher priority in cryonics procedures.
No, ischaemia is being adequately addressed, also (especially,
considering the resources) by the mainstream. Brain vitrification is
not.
> Another piece of good news (for cryonics!) is that ischemic damage
> is a very common event, for example stroke, that the brain
> has to some extent evolved to protect against, for example
> through redundant storage of long term memories. Brain
> damage from stroke is usually the result of loss of function
> of parts of the brain the function of which is to retrieve
> and process long term memories, rather than loss of the long
> term memories themselves. So after even a major stroke
> lasting for days the information is usually still there.
Stroke=focal damage. Ichaemia is global stroke. But again, ischaemia
itself is not a primary source of damage, if patient in optimal
settings, including premedication. Even postmedication stretches the
window a lot, and we're not talking merely structural preservation but
viability. I am not concerned about viability, the usual gold
standard, but structural conservation only.
> These are all testable claims and it would be great to
> discuss studies on hypothermia, stroke, etc. rather than
> continue to speculate. There also needs to be more
I have to tried minimizing speculation on my part. However, I've seen
that a lot of my arguments are being either ignored, dismissed or
misunderstood. I am beginning to see the origins of that often voiced
source of irritation.
> cross-disciplinary learning between computer scientists and
> cryobiologists.
Alas, so far information flow has been negligeable.
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