Deep Stops Increases DCS

[igor p]

I don't think so. The colors are relative so they don't show big and small. They show relative supersaturations in profiles of the same run time. Remember, it's a comparative exercise. How do profiles handle supersaturation compared to the other profiles. If all the colors between two profiles were the same, they would handle supersaturation the same. The differences in color show relative differences in how they handle supersaturation.

Again, absent the NEDU hard data points (A2 deep stop 5% DCS risk; A1 shallow stop 1.6% DCS risk) I would think you'd both be looking at the deep stops toward the left of the heat maps and all the "Red" in A1 and say "Wow, that's not good." It's only because we know what profile was actually better that the comparison is meaningful. And as a comparison its appropriate.

The problem is "relative".
It show 10kPa difference as red (hypotetically) and in another place 100kPa as green. I know what you want to show but that is inapropriate for the purpose. Shows differences wrong.

 

[Dr Simon Mitchell]

Looking at Baker graph I think Ross's graph is correct. Or I missed something...

Yes, you did.

All Baker's tissue state parameters appear as vertical lines. If you are going to refer to "supersaturation pressure", it must apply to a specific depth because the definition of supersaturation is:

Or more simply:

Pss = Ptiss - Pamb

Supersaturation pressure can only be defined at a specific depth. Ross's depiction defines it as crossing depths. You will see his "tissue gradient" also disagrees with Baker.

Since he is clearly lining up to try to discredit things I have said in presentations on this matter, I think it is important he gets off to an accurate start. Not a particularly good effort so far. I also worry about his basic understanding of these quite fundamental issues given he sells a related life support product in which he performed the calculations.

VR3 was nothing to do with us - they just wanted sell more products. It was longer than real VPM-B/E. So you have not dived VPM-B.

The idea of incorporating VPM in the VR3 was to increase deep stops (or are you going to try to deny that too?). You may recall that is the point I was trying to make. I believed in deep stops.

As an aside, you are really stretching credibility to suggest VR Technologies adopted the VPM name with no input or permission from you.

But Simon, you told us the nedu study convinced you in 2006, and most likely you knew about its progress before then. So... something still does not fit right.

No, you told us the nedu study convinced me in 2006. I have made no comment on the timing. It is irrelevant anyway (see above). I purchased my VPM VR3 before I knew anything about the outcome of the NEDU study. Occam's razor suggests that the simplest explanation for something is usually the correct on. Why not just accept that I believed in deep stops but changed my mind when new evidence emerged? Why imply these implausible conspiracy theories to the effect that (for some unspecified reason) I have hated the deep stop concept every since it was first proposed? Have you any idea how silly all this sounds?

Really? David seems to think its OK now.

I don't see where he says that. And parenthetically, I find your repetitive citations of David's opinion as though he supports you to be mildly amusing since this entire thread is dedicated to you attempting to trash his work.

But how interesting that you suddenly seem to understand these important differences... now - when it suits you. Your youtube "presentation", is devoid of such distinctions and uses that to incorrectly make conclusions that are not there.

What on earth are you talking about? My presentation that appeared on you tube used the exact same definition of supersaturation that I am advocating here. Go and watch it again. Nothing I have said is inconsistent with what was said in that presentation.

Simon M

 

[UWSojourner]

The problem is "relative".
It show 10kPa difference as red (hypotetically) and in another place 100kPa as green. I know what you want to show but that is inapropriate for the purpose. Shows differences wrong.

Read my post at the bottom. When supersaturations get "small", the colors adjust based on a higher value. You can see that is the case. Just look at C16. It has no Red in it. That is because the supersaturation remained relatively low throughout the dive.

But in any case, in those compartments that are more heavily supersatured, Red means "highest", not "danger". You keep trying to assign some absolute value to the colors when the colors are meant to draw out relative similarities/differences in the way profiles handle supersaturation.

 

[igor p]

Read my post at the bottom. When supersaturations get "small", the colors adjust based on a higher value. You can see that is the case. Just look at C16. It has no Red in it. That is because the supersaturation remained relatively low throughout the dive.

But in any case, in those compartments that are more heavily supersatured, Red means "highest", not "danger". You keep trying to assign some absolute value to the colors when the colors are meant to draw out relative similarities/differences in the way profiles handle supersaturation.

This aproach hides true differences and important data (significent differences) and show unimportant relative data.

 

[UWSojourner]

Theis aproach hides true differences and important data (significent differences) and show unimportant relative data.

It's hard to imagine what's "hidden"? You can see moment by moment for each compartment what they are doing relative to each other. And remember again, it's important because we KNOW the outcome of A2 and A1 in the NEDU study. I don't doubt that other comparative measures can be used - ISS, risk functions, etc. -- but this was, after all, just trying to do one thing. It was trying to visually compare the "complex on gassing and off gassing patterns" between the profiles.

But, at least you're now saying "I don't like the charts" rather than "The charts have errors". I guess I'll call this progress

 

[UWSojourner]

A difference of 13 kPa? ( 0.13 bar, 0.128 ATA)
Our codes correctly addresses the H20 in breathing air, and other gasses in tissue comartments. It is a deco program - based on peer reviewed codes and models.

I believe your decompression schedules use the VPM-B code that was published. You'll see the Pressure_Other_Gases variable in the code.

But when you made your "supersaturation" charts, you pulled the N2 and He pressures, subtracted Ambient and called that "supersaturation". And then used that calculation to conclude the heat map had errors. This was just incorrect.

But why the difference? 13 kPa is the same as the difference between 1 Bar and 1 ATA. These are often confused and used incorrectly. I'm pretty certain, that will be exactly the issue.

You picked the unit of measure (kPa) not me. The 13.6 kPa I added back in is 136mb. 1 bar is 1000mb; 1ATA is 1013.25mb. That's a difference of 13.25mb, only about 1/10th of the issue.

 

[igor p]

I believe your decompression schedules use the VPM-B code that was published. You'll see the Pressure_Other_Gases variable in the code.

But when you made your "supersaturation" charts, you pulled the N2 and He pressures, subtracted Ambient and called that "supersaturation". And then used that calculation to conclude the heat map had errors. This was just incorrect.



You picked the unit of measure (kPa) not me. The 13.6 kPa I added back in is 136mb. 1 bar is 1000mb; 1ATA is 1013.25mb. That's a difference of 13.25mb, only about 1/10th of the issue.

Ok. He just e-mailed me he found and corrected bug in graphing tool. He wanted to tell it himselfe, but unfortunately he is not alowed to post it. Just sent out new version of his programs.

 

[tridacna]

Ok. He just e-mailed me he found and corrected bug in graphing tool. He wanted to tell it himselfe, but unfortunately he is not alowed to post it. Just sent out new version of his programs.

Why is he not allowed to post it?

 

[igor p]

Why is he not allowed to post it?

Someone probably felt being personaly attacked, actualy dont know who was more personaly attacked Bruce or that person....and from whome.... but lets leave that being. Not completely correct by my judgement but it is not me to judge.

Well discussion seem silent.

I am interested if someone understood method Bruce used in his corelation....seem noone did from what I read. Have confirmation from Bruce it seem so from what he rrad.

 

[UWSojourner]

I am interested if someone understood method Bruce used in his corelation....seem noone did from what I read.

Nobody understood? You sound like the girlfriend who was just told her boyfriend no longer wanted to see her. She exclaims, "You don't understand me!" And the boyfriend says, "Actually I do understand. I understand that you're frickin' nuts!"

Here's what I read:

Leadduck Post - the conclusion of the Wienke's paper should have been that all the models were useless in explaining the data, including his.

Doolette Post

• most of what is written in the Wienke paper(s) is unclear
• none of the models fit the data better than simply assigning identical risk to all dives within certain depth ranges
• the paper contributes nothing to the debate about whether deep stops or shallow stops are more efficient
• For more information (detailed) about Doolette's understanding see posts 800, 801, 809, and 816.

Mitchell Post

• claims of nothing but nominal DCS in deep stop models are simply wrong.
• unethical to make misleading claims about DCS incidence while marketing a product
• inconsistent peer review
• reminds readers that Wienke does have a financial interest in the topic and that it was undisclosed as a conflict in the paper

I think it's safe to say someone understood.