Dr Deco
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Hello gcbryan:
This is a continuation of a thread started on July 16, 2009 by gcbryan
Nuclei
Regarding nuclei origin I think your point is that some of it is random, some can be determined by traditional means, and some of it is determined by exercise. Is that correct?
I am not certain what is ment by can be determined by traditional means. There is no way to see the nuclei in tissue even with some decompression to enlarge them since tissue is largely opaque. The nuclei are postulated to exist since the small pressures involved in diving could not generate nuclei in a fluid; seeds must be present. Seeds are present in all fluids: water, organic liquids, even lava.
These seeds originate, I believe, from thermal activity. All fluids will generate nuclei by thermal motion. [When temperature approaches boiling, you can see the nuclei as they are millimeters in diameter.] This idea was first elucidated by E.N. Harvey [somewhat like this] during WW II.
This same investigator recognized that nuclei could be enlarged with exercise to produce the microbubbles that grow with supersaturation. What was not known was this nuclei concentration is not the ground state [might we say]. If individuals sit for several hours, they can reduce the nuclei concentration to quite low levels. Astronauts in orbit do not walk and thus lose the nuclei in their legs and to a lesser degree their arms. This was my conclusion from my work at NASA, and it could explain why DCS in space is much lower than predicted from ground-based tests.
Exercise can enlarge nuclei or decompression bubbles even more when it creates a region of low pressure in tissue. This exercise immediately following a dive can be harmful.
Halftime Tissues
What I'm really looking for (in simple terms) is what your thoughts are regarding current decompression theory, what is clearly wrong, what is right and known for certain (if anything).
What is wrong with current models? For one thing, the compartment concept is better as a bookkeeping scheme than an actual model. There is probably only one tissue in a given region that causes pain, and the gas uptake and unloading are determined by blood flow [perfusion]. The compartments attempt to cover all bases by tracking everything. However, that it is an approximation that fails when dive conditions change considerably. Diving warm and decompression cold is one example as is lying down to sleep during off gassing. In these instances, we switch from faster to slower compartments.
More Models
What a better model would need to address such as perhaps linear off gassing with exponential on gassing or parallel compartment modeling vs. in series. What's important and what's not.
Linear off gassing probably does not occur unless a free gas phase has formed. These bubbles are present in saturation decompressions where the ascent rate is 4 feet/hour.
The addition of bubble nuclei in the more contemporary models is a nice advancement.
Dr Deco :doctor:
This is a continuation of a thread started on July 16, 2009 by gcbryan
Nuclei
Regarding nuclei origin I think your point is that some of it is random, some can be determined by traditional means, and some of it is determined by exercise. Is that correct?
I am not certain what is ment by can be determined by traditional means. There is no way to see the nuclei in tissue even with some decompression to enlarge them since tissue is largely opaque. The nuclei are postulated to exist since the small pressures involved in diving could not generate nuclei in a fluid; seeds must be present. Seeds are present in all fluids: water, organic liquids, even lava.
These seeds originate, I believe, from thermal activity. All fluids will generate nuclei by thermal motion. [When temperature approaches boiling, you can see the nuclei as they are millimeters in diameter.] This idea was first elucidated by E.N. Harvey [somewhat like this] during WW II.
This same investigator recognized that nuclei could be enlarged with exercise to produce the microbubbles that grow with supersaturation. What was not known was this nuclei concentration is not the ground state [might we say]. If individuals sit for several hours, they can reduce the nuclei concentration to quite low levels. Astronauts in orbit do not walk and thus lose the nuclei in their legs and to a lesser degree their arms. This was my conclusion from my work at NASA, and it could explain why DCS in space is much lower than predicted from ground-based tests.
Exercise can enlarge nuclei or decompression bubbles even more when it creates a region of low pressure in tissue. This exercise immediately following a dive can be harmful.
Halftime Tissues
What I'm really looking for (in simple terms) is what your thoughts are regarding current decompression theory, what is clearly wrong, what is right and known for certain (if anything).
What is wrong with current models? For one thing, the compartment concept is better as a bookkeeping scheme than an actual model. There is probably only one tissue in a given region that causes pain, and the gas uptake and unloading are determined by blood flow [perfusion]. The compartments attempt to cover all bases by tracking everything. However, that it is an approximation that fails when dive conditions change considerably. Diving warm and decompression cold is one example as is lying down to sleep during off gassing. In these instances, we switch from faster to slower compartments.
More Models
What a better model would need to address such as perhaps linear off gassing with exponential on gassing or parallel compartment modeling vs. in series. What's important and what's not.
Linear off gassing probably does not occur unless a free gas phase has formed. These bubbles are present in saturation decompressions where the ascent rate is 4 feet/hour.
The addition of bubble nuclei in the more contemporary models is a nice advancement.
Dr Deco :doctor:
