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>      "John" from Brown University, and Peter Hazeltine. John never has a
> clue, and Peter subscribes to the worst bullshit possible. How did you get
> in this? These guys obviously have never been diving. How about it: let's
> say I have pure O2 only for a dive, like in a LAR 5 rebreather, but I drop
> my gun, and it falls in sixty feet of water. I can see it on the sand. If I
> hold my breath, is it ok for me to drop down and pick it up? You know the
> answer to that, Mr. Pyle, but these two ignorant fucks do not, or they would
> not be making assholes of themselves in public. 

Hmmm...  I suspect they both do know the answer to that, but I think 
we're all having a tough time figuring out what the question is. What is 
the original point that you're referring to?  If I remember correctly, 
the (valid) question was raised about whether total volume of N2 absorbed 
(which can vary from person to person) was also an important 
consideration in addition to the PN2 (=depth/time dose). I don't know the 
answer to that, do you? Everybody is so focused on partial pressures, 
that they forget other factors can come into play.  

A related concern is the solubility of a gas.  N2 is MUCH more soulble
than He.  So at a given partial pressure, there would be many more N2
molecules available for bubble growth than there would He molecules. I 
believe the general consensus is that DCI is caused by gas-phase bubbles 
in the blood and tissues, not elevated levels of dissolved gas partial 
pressures.  The reason the eleveted partial pressures are important is 
that they affect rates of bubble growth and shrinkage. But the partial 
pressures are certainly not the only thing tht affects bubble growth and 
shrinkage.

So my question to you is, what did John or Peter say that made you think
they didn't understand that alveolar partial pressures were a function of
inspired gas fractions and ambient pressure? 

Aloha,
Rich

P.S. As for your spear gun, the answer is easy.  Go to the surface, flush 
the loop with air, drop down to about 45 feet on the rebreather, shut the 
input supply, hold your breath, go get your gun, come back to shallow 
water, then flush the loop with O2.  This isn't rocket science.

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