NEDU Study

[Diver0001]

Then what did you mean by that?

R..

 

[UWSojourner]

My beef with all this, is like I expressed to Bruce - when is this creeping of unnecessary extra deco time going to stop? There is no valid reason for it.

The NEDU study does not call for any extra deco time. The implication of the study is the following:

Given the SAME decompression time, shallower stop models (like GF) are likely more efficient at distributing that time than a deep stop model (like VPM-B). SAME time, lower DCS risk.

There is no call for longer times. Just a recommendation to use a model that redistributes the time you do spend decompressing toward shallower stops.

That's the NEDU study.

However, there are also interesting studies observing bubbles in divers. Those bubble-count studies have also confirmed that deep stop profiles produce more bubbling in divers. And in response to those studies divers have extended their shallow deco time to get their post-dive bubbling down. So, yes, times might be getting longer, but with good reason -- to reduce the amount of bubbling a diver experiences.

 

[Kevrumbo]

C'mon Ross . . ."at long last, have you no sense of decency?"

Hi,

I have met all those people except one...

Andrew Ainslie used to be our CCR X1 and X-Link tester... He and I talked often about his diving and feedback on VPM-B and the programs. He never once mentioned a single problem to me or anyone... And then one day, a year after he shifted to a different computer brand... he suddenly remembered 13 incidents..... I don't believe it, and neither should you. But we have all his dive logs, so I asked him to point out which ones gave trouble, so we can all take a look.... still waiting.. . .
..

Geez Ross, now denying former product testers . . .and especially someone who was an apologist and friend to you?:

Ross

We've been friends for many years, and it saddens me to watch you get into this battle.

You are way, way out of your depth and your description of Simon as agenda driven just doesn't bear scrutiny.

Simon is a world renowned scientist, and has always been one of the most cautious, circumspect people that I know. There is no way that he would risk his stellar reputation in a pissing match on a board like this unless the evidence was squarely on his side.

Furthermore, all of his comments have been measured, cautious and acknowledging that research, by its very nature, results in a changing set of views about the most likely way that the world works. While all you do is desperately cling to the perfection of a 20 year old hypothesis.

Science doesn't work the way you want. It works the way that Simon describes.

I don't understand most of the papers he alludes to. But give me a break, nor do you. We are incredibly fortunate to have someone like Simon on these boards helping us to understand these things. And what agenda could he possibly have? His task is to get papers through the peer review system. Agendas rarely survive the spotlight of the peer review system, at least in the top journals.

I know you love VPM. But it's just one theory. It's a simplification of a horribly complex physiological system. And hardl anyone studies this physiology because no one gives a ****. Other than a handful of astronauts and high altitude pilots, a few thousand commercial divers and a few thousand dumbassed recreational divers like the ones on this board, no one does this stuff. Dengue fever has probably hurt a lot more people than dcs, and dcs is given little attention as a result.

So, thank god for Simon for two reasons: 1) for studying this tiny little corner of medical science with such diligence and 2) for being willing to come to boards like this and explain it to numbskulls like us, even when under attack from amateurs like you and me.

I'm sure this will win me no kudos from you, Ross, but it needed to be said.

Regards

Andrew

Re: Andrew Ainslie
Deep stops debate (split from ascent rate thread) - Page 4

 

[scubadada]

C'mon Ross . . ."at long last, have you no sense of decency?"
(Geez Ross, now denying former product testers . . .and especially someone who was an apologist and friend to you?):

Ross

We've been friends for many years, and it saddens me to watch you get into this battle.

You are way, way out of your depth and your description of Simon as agenda driven just doesn't bear scrutiny.

Simon is a world renowned scientist, and has always been one of the most cautious, circumspect people that I know. There is no way that he would risk his stellar reputation in a pissing match on a board like this unless the evidence was squarely on his side.

Furthermore, all of his comments have been measured, cautious and acknowledging that research, by its very nature, results in a changing set of views about the most likely way that the world works. While all you do is desperately cling to the perfection of a 20 year old hypothesis.

Science doesn't work the way you want. It works the way that Simon describes.

I don't understand most of the papers he alludes to. But give me a break, nor do you. We are incredibly fortunate to have someone like Simon on these boards helping us to understand these things. And what agenda could he possibly have? His task is to get papers through the peer review system. Agendas rarely survive the spotlight of the peer review system, at least in the top journals.

I know you love VPM. But it's just one theory. It's a simplification of a horribly complex physiological system. And hardl anyone studies this physiology because no one gives a ****. Other than a handful of astronauts and high altitude pilots, a few thousand commercial divers and a few thousand dumbassed recreational divers like the ones on this board, no one does this stuff. Dengue fever has probably hurt a lot more people than dcs, and dcs is given little attention as a result.

So, thank god for Simon for two reasons: 1) for studying this tiny little corner of medical science with such diligence and 2) for being willing to come to boards like this and explain it to numbskulls like us, even when under attack from amateurs like you and me.

I'm sure this will win me no kudos from you, Ross, but it needed to be said.

Regards

Andrew

Deep stops debate (split from ascent rate thread) - Page 4

Thanks @Kevrumbo I did not initially realize that you said that 3 1/2 years ago until I clicked on the link

 

[Dr Simon Mitchell]

These basic facts still remain:

* The nedu did not test proper deep stops or our tech models,

* The nedu test did not "protect its fast tissue" as claimed,

* The nedu test does not have "similar supersaturation patterns" to a tech or deeper stop models, as claimed.

Those most basic components of the anti-VPM/anti-deep stop argument, do not exist. The central premise of their connection to tech argument, is simply not there.

Only on Planet Ross.

The scientific logic that connects the NEDU study to VPM was first discussed in the NEDU study report where (using integral supersaturation) they compared their profiles to 500,000 other possible profiles, some of which inevitably emulated VPM. A more specific comparison with VPM was presented by Dr Doolette (the NEDU study lead author) here:

Deep stops debate (split from ascent rate thread) - Page 20

.....and in the presentation that UWSojourner linked to earlier.

Finally, the connection between more typical tech dive profiles prescribed by VPM has been promulgated by UWSojourner, using essentially the same integral supersaturation approach as Dr Doolette, for example, here:

Deep Stops (rebreather dive charts)

All of these comparisons have concluded the same thing.

There is an obvious thread of scientific methodology and logic throughout this sequence and you can deny it as much as you like, but there certainly is science to connect the NEDU study and VPM.

So why do they keep exaggerating for no apparent good reason? Its not needed or justified from a deco perspective, so I can only assume its for mundane reasons. Its more than double time now, so any reasons for deco profile stress has long since been left behind.

Where or when is all this unnecessary time creeping going to stop?

As UWSojourner has pointed out, you are conflating two separate debates. The principle discussion is about the efficiency of deep stops approaches to decompression. That is, if you have a fixed amount of time to spend decompressing, what is the best way of distributing that stop time across the range of decompression stop depths?

A separate discussion which has arisen along the way is the use of extended oxygen stop time to reduce risk (and using choice of gradient factors to drive this). You have consistently rubbished this notion despite the fact that the scientist who you seem most happy with (Neal Pollock) has dedicated a lot of his time recently to demonstrating that it appears to work (in as much as VGE counts indicate decreased risk).

I put it to you that you are unqualified to comment on this matter, and you have no idea whatsoever whether your deprecation of this idea could potentially result in harm to divers who might listen to you. You have no idea of the true incidence of DCS in technical diving. You don't measure it and it is not like every diver who gets sick thinks, "Oh, I have DCS, I better call Ross Hemingway and tell him". In contrast, I have been the expedition doctor for 9 major expeditions involving between 12 and 40 technical divers diving twice daily for 1 - 2 weeks. These divers talk to me about their problems (although even in this setting I am sure there are some who still conceal them) and I can tell you that the incidence of DCS (mostly mild) in this setting is far higher than YOU think it is. As the person who has to advise and sometimes actively care for the divers in these remote location, this focuses my attention on risk reduction. Padded shallow oxygen stops is one strategy which we think works. The data are not definitive (yet), but it makes biological sense and I think you should be very careful about the statements you make in relation to this matter.

Simon M

 

[Storker]

What we have at the moment, is one overly interested Dr. who bypasses the proper review process, and takes the message direct to the public... So now its about trust in one person only to represent all of science.

Are you accusing @Dr Simon Mitchell of unethical conduct?

R..

No.

Not any more, you mean. Good for you that you edited the paragraph that R. quoted out of your post, because you certainly did so before you made that edit.

 

[huwporter]

1/ The VPM-B+7 that is used in the diagrams above, does not exist, no one can make it, you cannot buy it. It's something that was created by Kevin for this purpose only. It's a stretched out exaggeration, and used to make a non-existent comparison. We are not allowed to just make stuff up.

A VPM-B+7 profile is virtually identical to the profile from VPM-B+5 for a roughly 20% longer bottom time. Ross, can you explain why a profile that is apparently absolutely fine for one bottom time suddenly becomes "made up", "exaggerated" and "non-existent" when applied to a slightly shorter bottom time?

Demonstration:

(Miniscule differences only caused by rounding to whole minutes.)

You didn't answer this question the last time this came up, I'm just really intrigued as to why you declare that VPM-B+5 is fine and conservative, but VPM-B+5 for a slightly longer bottom time suddenly turns in to something crazy and made up that apparently actively hurts you...

Limits on the parameters of VPM ?

That's been discussed rapidly there, I did not succeed in running the original fortran code as it broke my IDE at the time and could not deal with that at that time. I might look further into it someday... Surely one could plug in the right parameters in one of the various C implementations of VPM.

Or just run the profile for a ~20% longer bottom time...

 

[Dr Simon Mitchell]

Ross,

I note from the text quoted by Diver0001 ("one overly interested Dr") that you are back to the strategy of attempting to portray me as a lone voice. This is so easy to disprove in multiple ways, but since it comes up repetitively I wanted to pick up on this comment as an example:

The nedu test did not "protect its fast tissue" as claimed,

Could you please watch the video (minute 33:14) here:


...and tell me where you think Dr Doolette is wrong in his claim that the NEDU deep stops profile protected the fast tissues in comparison to the shallow stops profile, and where his opinion differs from mine?

Thanks,

Simon M

 

[nadwidny]

Thanks @Kevrumbo I did not initially realize that you said that 3 1/2 years ago until I clicked on the link

He didn't. The post was Ainslie's

 

[Schwob]

Ross,

I note from the text quoted by Diver0001 ("one overly interested Dr") that you are back to the strategy of attempting to portray me as a lone voice. This is so easy to disprove in multiple ways, but since it comes up repetitively I wanted to pick up on this comment as an example:



Could you please watch the video (minute 33:14) here:


...and tell me where you think Dr Doolette is wrong in his claim that the NEDU shallow stops profile protected the fast tissues in comparison to the slow tissues, and where his opinion differs from mine?

Thanks,

Simon M

Not that it means much in the midst of what just really ever increasingly appears to be Ross' persistent obfuscation campaign, imho horribly abusing this wonderful web resource here. But hey, considering that we seem to be entering a new age of government sponsored and created alternative facts anyway, maybe thats the new normal... Even so, I just cannot help but to state (and yes, that is just one (more) persons opinion)

After careful consideration, I and the 100 hydraulic pins in "Dr. Doolette's chamber" attest to there being absolutely nothing wrong with his presentation in this video, nor with the facts presented, the logic employed or the conclusions drawn. Really, what could any reasonably thinking person possibly see wrong with what is stated in that video? Certainly a scientific oriented person could not. Of course there could always be arguments along the line of "this is outside of my belief system, therefore it is heresy". But come one were beyond this here. This is based on good science, good test data, ... this is good stuff...