On Thu, 21 Oct 1999, Spike Jones wrote:
> If we are concerned with the Radioactive decay for cryonic preservation
> (now that I think about it, I believe it was Robert Bradbury that started
> this thread)
Me?!? I thought I was responding to one of your comments! Although this does follow from the dicussion back in August where were were discussing the radiation damage resulting from supernovas.
> then we also need to think about what effect typical ionizing
> radiation has on matter at liquid nitrogen temperatures.
Well, at LN2 temperatures you don't have very much chemical reaction taking place, so what will happen is the accumulation of "unusual" molecules. They will not be very different from the molecules that are normally found in the body (after all are exposed to radiation every day) but they will accumulate to higher levels than we normally encounter.
> The potassium
> decays would be predominantly in the skull, the bony material having
> much more patassium than the brain itself.
Actually in the brain you presumably have a high K level in solution since the neurons pump Na/K in and out to fire the neurons. I'm unsure whether cerebral-spinal fluid has a higher K concentration than blood in general though.
> I think that radiation would be of little consequence in comparison to
> the transmutation of elements resulting from beta decay. spike
As I showed in my discussion regarding DNA, you can probably tolerate a fair amount of transmutation (C->N) and since K goes to Ca that isn't going to hurt anything. Since the biological effectiveness of alpha radiation is so much greater, I'd put my bets on that as being a major player. But we need to know in fine detail the quantity of various radioactive isotopes in the body, their decay paths, the molecules they are in, etc. to know exactly what the downstream effects would be. Most of the C is in proteins and not in DNA and so the 14C decay may have more significant consequences for enzyme function than it will for DNA preservation.