From: Jeff Davis (jdavis@socketscience.com)
Date: Tue Dec 14 1999 - 14:54:14 MST
On Mon, 13 Dec 1999 12:41:47 -0800 (PST)
Eugene Leitl <eugene.leitl@lrz.uni-muenchen.de> writes:
>When we're talking about kilogees, remember car accident trauma. The
>brain, despite floating, does not seem to tolerate orders of magnitude
>more than ~10 g.
I must confess that this is the sort of hard empirical reality that
challenges one to pay attention to details.
I think the problem is impact/shock loads, and point loading (as well as
sudden torsional loads, as gene mentions).
>From the design of the mechanism, I think it is clear that spinning up the
centrifuge implies a gradually increasing g loading. (Clearly my example
from my last post of 1000 gees for 1 second does not lend itself to
"gradually increasing g loading").
In an auto accident where the head suffers an impact, the loading occurs
abruptly and at a point (and if the line of action is not aligned with the
center of mass, is accompanied by a wicked torque). This results in a
shock wave eminating from that point, going through the brain, and
depending on damping rate, being reflected (with no small degree of
complexity) from the interior surface of the brain pan, back through the
brain. Conceptualize the difference between this and a gradual build up of
g load. No shock wave.
As I mentioned before, the moulded body support distributes the stresses
associated with point loads.
>Also, fluorocarbons have roughly twice the density of water
>(yoicks!). I see trouble both for the lung as a whole, and the
>alveolae. Lots of petechiae.
Or worse, gross lung rupture. Yes, this is a deal killer. Gotta find a
fluid that is closer to body density. Which shouldn't be all that hard
actually. If the electrolytes are balanced to prevent edema, something
like saline should do. If you are looking for a longer duration, something
to provide blood gas exchange, you'll need to be more particular. Hmmmm.
Do you suppose blood sans platelets would do the trick? The density,
electrolytes, and blood gas transport characteristics are right.
--------------------------------------------------
By the way,...I want to thank gene for his part in this thread. As always,
he tends to clean up the signal,...whatever little bit of it there may be.
As for spike. Shame on you, spike! All these wonderful gizmos, and all
you can think of is a few pitiful guppies? What about the Hamsteroids of
China Lake? And don't they have tours for the public every so often?
Couldn't you have, with a benign wink to his mother, pulled little Billy or
Joey off to the side and said, "Do you know what a centrifuge is? Everyone
knows that to become an astronaut you have to ride in a centrifuge? Would
you like to become an astronaut some day, Billy?(or Joey?), etc." Then we
would have some hard data, dammit! But all you ever think about is your
security clearance, your career, and staying out of jail. Wimp! And you
call yourself an extropian.
Best, Jeff Davis
"Everything's hard till you know how to do it."
Ray Charles
This archive was generated by hypermail 2.1.5 : Fri Nov 01 2002 - 15:06:04 MST