Vanderzyden

Rufus,

Your responses tell me that you are not familiar with the second half of this thread. That link was discussed several pages back. Please go back and read from that point to here and your questions should be answered. If not, then ask pointed questions.


John

RufusAtticus

Well, I guess I'll just do the math myself. If I am wrong, Vander, please give us your calculations to correct me.

From Vander's link, the hydrostatic pressure difference between two levels of a liquid is

• delta_p = r*g*delta_h.

delta_p is the change in pressure
r is the density of the liquid
g is the acceleration due to gravity
delta_h is the change in height

Okay, now let's calculate the total pressure difference exerted on the walls of a container that is both filled with a liquid and submerged in it.

Pressure difference inside: delta_p1 = r*g*delta_h.

Pressure difference outside: delta_p2 = r*g*delta_h.

Net difference in pressure: delta_pnet = delta_p1 - delta_p2 = r*g*delta_h - r*g*delta_h = 0.

Q.E.D.

~~RvFvS~~

BTW: If I missed the post where you said what the dimensions of the fetus are please point it out to me. Otherwise, provide them. How is that for a pointed question?

[ November 06, 2002: Message edited by: RufusAtticus ]</p>

pz

Since Vanderzyden has been dodging Coragyps "simple" problem (If I laid a two-inch Schedule 40 mild steel pipeline from the deepest point in Lake Superior to a point six inches below the surface, how many hydraulic horsepower would be required to pump five gallons per minute from the lower end to the upper? And how much to pump from the upper to the lower?), I think at this point that it's reasonable to assume that he is incapable of doing it.

That's another Vanderzyden challenge that he has failed to meet. Is anyone keeping score?

Vanderzyden

No, Rufus. You do not understand that transmural pressure (the second half of your analyis) is not what we are considering in this design critique of the internal CV system. Perfusion (i.e. internal point-to-point) pressure is what we need to analyze. The effects of transmural pressure are negligible.

No calculations are necessary. However, your attempt grasp of simple concepts would be nice, and is easily achieved if only you would take the time. So, please go back and read.

If you reply in a similar fashion again in this topic, you will understand why I don't respond.

Thank you for your consideration,

John

pz

This is not a constructive reply. You have said that this is a simple calculation...so just do it. Poor Rufus is a mere biologist, so it isn't particularly interesting to say he got it wrong (especially since his answer looks OK to me). Just whip out that ol' calculation that shows that you really know your stuff. Fascinating. So do you think this would be the best tactic we should follow in response to you, when we see your uninformed mangling of basic concepts in biology?

Do you know what "irony" means?

RufusAtticus

And the internal point-to-point pressure is canceled out by the external point-to-point pressure. Transmural pressure is only neglibible if the outside is much more less dense than the inside, i.e. delta_pnet = (r_in-r_out)*g*delta_h ~= r_in*g*delta_h. However, in this situation the densities are the same. Thus it is not neglibible. However, if I am wrong, provide your calculations.

LOL. Try publishing any scientific work with that attitude. I asked you for you calculations. Can you provide them or not? If you can't, then your argument has zero basis.

I've kept up with this thread. And nowhere have you provided any calculations that prove that for fetal circulation (or a reasonable model of it) transmural pressure is neglibile.

Of course I will understand. You haven't done any calculations, and know that when you do they won't support your argument. Ergo, like any master crackpot, you descide to ignore critism rather then address it.

If you are so extremely skilled at fluid mechanics over us lowely biolgists, then it should be child's play to show us the calculations that prove your position and refute ours. I can only wonder why you have completely refused to and avoided the obvioius finishing move.

~~RvFvS~~

[ November 06, 2002: Message edited by: RufusAtticus ]</p>

Vanderzyden

That's a bit better. Now, tell me how it the transmural pressure "cancels" the perfusion pressure between, say, the left subclavian and the superior mesenteric artery (i.e. along the aorta).

Oh, "crackpot", did you say? You refuse to read the thread and also start the insults. One more time is all that's necessary to end our conversation.


John

Doubting Didymus

Vanderzyden, Why can't you just show us the calculations? For a physics layman like me, who is not capable of working out this problem for himself, it is very frustrating that you refuse to demonstrate your argument in any way that I can think about.

This is a simple request. You say that physical calculations support your pressure hypothesis. Please please produce them, else what are we to think, other that you can not do so?

RufusAtticus

The fluid pressure due to gravity inside the vessels are canceled by the fluid pressure due to gravity outside the vessels. See the above two posts of mine for my calculations. If my calculations are wrong, just show me the right ones. It is as simple as that.

Three quick characteristics of a crackpot.
<ol type="1">[*]Failure to provide support for claims.[*]Contradicting known and well supported research.[*]Ignoring and failing to address criticisms.[/list=a]

Hmm, sounds like you fit all three. Now if you don't want to be a crackpot, just give us your calculations. Of course, if you were capable of doing that you'd already done it. Too bad you seem unable to admit that to yourself and us.

Reading all posts in the forum is a requirement of my moderation duities, so I have read this thread. However, I can miss things. If you have provided calculations that support your claims, then tell me on what page they exist and I will appologize for missing them and considering you a crackpot. It's that simple. Otherwise, show me the math!

Ooooo, threatening to not listen to me will like so uncrackpot you.

Are you really ready for SCPL3?

~~RvFvS~~
BTW.1: I'm still waiting for you to tell me what the fetal dimensions are you mentioned earlier.

BTW.2: You do realize that by not posting calculations of you own you are effectively conceding that mine are correct.

[ November 06, 2002: Message edited by: RufusAtticus ]</p>

Rancid

Time travel is possible. I am an expert at this with years of study under my belt. The math involved is simple... but you have to take my word for it, for I will not actually show anybody any equations or research that I have done.

Sounds silly, doesn't it?

Please provide us with those calculations, Vanderzyden. It should only take a few minutes to prove your point.