L2/R2, could they be nonsensical?

As this is maybe a first point of agreement between Fleury and myself I promised to make of it a post.

In a recent comment he wrote:

The question of cell vortices and stream lines is nonsensical.

I totally agree with that. The absence of L2/R2 visualization make them nonsensical. And the « stream lines » seem probably nonsensical to me and are certainly not yet supported by evidence.
Let’s see why I connected them. Err… I didn’t connected them, Fleury made the connexion. And he’s the same that claim the four vortices and the « stream lines ».

Let’s see the story board with a luxury of links.

In #1 of my discussion on EPMAG I pointed to the fact that in the introduction only two vortices are presented, by the only author of the paper, that is Vincent Fleury. And I pointed out that there was no mention of the four vortices claimed later on in his website:

So, the model is based on the presence of two vortices, schematically presented at fig 2. Later, Fleury presented us four vortices, each causing the budding necessary to form a limb. But this late hypothesis, implicating four vortices, isn’t presented in this paper. I haven’t see it in another of Fleury’s papers; so it goes as unpublished, not yet peer-reviewed, as well as unsupported by data.

In the comments of this post, Fleury answered: (emphasis added here)

Oh, sorry I forgot, the 4 vortices are in the organogenesis paper, if you can read,a nd also in the Phys Rev paper.

So, can I read or not? I gave it another run, but didn’t found any mention of four vortices of cells. And asked for precision.

Oh, where exactly?

Fleury’s reply was in his always charming manner: (emphasis added here)

completely ridiculous, nonsensical, wrong, defamatory etc.

if you cannot even spot the four vortices in Fig 6 of the paper “An elasto plastic model of avian gastrulation” you have nothing to do in science and your pseudo review of my paper is just nothing

Well, in fig 6 there are « stream lines » shown, not the four expected vortices, so I gave it another try:

a) you don’t want to help by saying where exactly the four vortices are shown, mentioned in “An Elasto-Plastic…” Not kind of you. But I do understand, the last time you tried to show them you produced an horrible mistake.
Let me help you with: “It requires a huge cellular motion which has the shape of two vortices converging towards the posterior pole an along the antero-posterior (AP)”. Remember? You wrote that!

Not a good idea, the outcome being: (emphasis added here)

a) you don’t want to help by saying where exactly the four vortices are shown,

the answer to that was clear enough:

if you cannot even spot the four vortices in Fig 6 of the paper “An elasto plastic model of avian gastrulation” you have nothing to do in science and your pseudo review of my paper is just nothing”

if you do not understand that two dipoles head on generate 4 vortices, as shown in Fig 6 of that paper,

your brain is off

If your fingers are not, please put here the figure in question, I give you permission.

So, Fleury established the connexion between the « stream lines » of fig 6 and the four vortices, two of them being the L2/R2 I’m trying to locate. Clearly, twice, affirmatively and suspecting that if one is not able to make the connexion his brain is off. This was on october 19.

I presented fig 6 and discussed it. His reply is certainly quite scientific and with brain on ON position. And he offered confirmation. That is, to be clear to people that wouldn’t follow links: « oh dear how “beeeep” »

Then, suddenly, the question became nonsensical.

  1. The guy first tried to locate them making a mistake.
  2. Then he pretended that the four vortices were present in the paper.
  3. No, no cell vortices presented in EPMAG, but he say so…

  4. Then he considered that my inability to see the connection between « stream lines » and cells’ vortices was due to « brain off ».
  5. As an answer to the remark that he messed up considering the result (« stream lines ») to be the cause (cells’ movements) he simply replied « oh dear how “beeeep” »
  6. Now the question is nonsensical.

We progress. But, he should have told me at first! Two months ago.

And, if he really thinks the question is nonsensical, why did he tried to answer it producing nonsensical drawings? Pretending he have presented the four cell vortices in EPMAG? And making the confusion between « stream lines » and « cell vortices » (IMO, another mistake).
What made him change his mind?
If the question is really nonsensical should he ask for a corrigendum at Organogenesis as he seems to consider that he discussed it in EPMAG?
Maybe by the same occasion he could ask to reconsider the « sandwich » composition as recently it have changed, from a stiff membrane (ECM in the text)/cells layer/stiff membrane(ECM in the text), to something different:

The structure of the sandwich does not matter. The structure of the top plate has no importance, there may even be no top plate at all, the system may aswell be a simple mix of an extra cellular matrix and cells.

Is it, also, a nonsensical question to ask WTF the description of the « sandwich » is doing in the paper if it doesn’t matter?
And this is an open question to physicist, if there are any around, other then Fleury: I always read about Poiseuille flow as being the flow of a viscous fluid in a channel. Would it apply to a viscous fluid, fluid by analogy, not constrained by an upper membrane as in the new « sandwich » definition?


9 Réponses

  1. Sir

    you should stop, you understand truly nothing :
    in thin shells, viscous dissipation is dominated by the gradient of speed across the small thickness distance. Between two plates, its Poiseuille flow, when there is a single plate it is a Couette Flow, but the flow is shear-driven in almost exactly the same fashion except that in the first case the lubrication approximation is correct at order (1/h2) while in the second it is correct at order 1/h
    the blastula beeing a 100 times larger than thick, the Poiseuille flow is correct at order 1/10000 while the Couette flow is correct at order 1/100.

    Your comments are so negative. You do not even try to understand deeply the problem.
    Now your question about streamlines and vortices is nonsensical. My theory calculates the flow field everywhere. In cells and out cells, everywhere. If you follow a cell, for example, by marking it with a fluorescent dye, what you see are trajectories, if you mark something else, say some protein in between cells, you will evidence the speed of that thing.
    Of course trajectories make vortices, if the flow (streamlines) revolves in vortices, but there is a mismatch between the two, which I explained when you did the error of overlapping trajectories with fluid flows, because stream lines are the curves tangent to the velocity field (i.e., integrals of trajectories with normalized tangent vectors) while trajectories are trajectories ascribed to follow the vector field with the correct vector magnitude.

    Flows exist, they form vortices, and there even is a saddle point, as predicted by my theory-model whatever you feel like calling it I do not care. It’s cool anyway.

    All what you say is complete rubbish, I am sorry to say it loud and clear, you make a fool out of yourself. Completely, For God sake, or rather Science sake please stop. STOP.

  2. By the way, Kees Weijer and co workers at Dundee do the job very finely, they show the fluorescence trajectories in one picture, and they show the streamlines in another
    Please put here the picture of the saddle point which I asked you several times to put, and you will see that there are streamlines making vortices, and so cells have trajectories in the shape of whorls.
    I do not understand why you do not want to put this figure, if you believe it has nothing to do with my point.
    It was on my website, though.

  3. après réflexion, I think the viscous thin layer free surface flow is also called Poiseuille flow. Makes no difference

  4. Well, I did the error?
    What’s that then, on A of this figure?. That was on your website and you called that cellular flows. Remember?

    Once more, where are they? Can you show them?

  5. Oh, you should contribute to correct the Wikipedia’s entry about Couette flow:

    In fluid dynamics, Couette flow refers to the laminar flow of a viscous liquid in the space between two surfaces, one of which is moving relative to the other.

    You are certainly right:

    Between two plates, its Poiseuille flow, when there is a single plate it is a Couette Flow,…

  6. après réflexion, the same goes for Poiseuille’s law:

    Poiseuille’s law is the physical law concerning the voluminal laminar stationary flow Φ of an incompressible uniform viscous liquid (so called Newtonian fluid) through a cylindrical tube with constant circular cross-section.

    You are certainly right:

    après réflexion, I think the viscous thin layer free surface flow is also called Poiseuille flow. Makes no difference

  7. […] time questioning his assertions. Not from my point of view, from the one of other physicists. [#1, […]

  8. Sir

    you truly understand very little if not nothing.

    I gave you a complete answer, perfectly understandable accurate, and directly applicable to your concern. You did not understand it. There is no way you can comment my work, at any level.

    However, once more I give you a full answer :

    The laplacian of the speed contains two terms, an in plane one, and a « across plane one » (see my paper)

    due to the thinness of the blastula, only the across plane matters.

    This comes from the derivative of the profile of velocity across the plane. This profile is parabolic for a two plates problem, half-parabolic for a single palte problem.

    It makes absolutely no difference whether it is a poiseuille flow between two plates, or a poiseuille flow with no upper plate for the model, it is just a prefactor of 2, the gastrulation simply proceeds more rapidly with a single plate.

    see for example


    as I told you, the one « plate » problem, is one half of the « two plates problem »

    That’s all. Instead of appreciating what I do, understanding it and maybe deriving interesting and important conclusions, you scorn, ironise, etc.

    Think that my work, will eventually, be ripped off. Let me shrug my shoulders, again.

    You make a fool of yourself.


    If I understand well this dispute at this stage

    You agree that the blastula is very thin

    You agree that there is a special region which contracts (Kollers sickle), becoming a rod almost centred on the intial sickle (hence there is a forward (rostral) and a backwards (caudal) deformation around a neutral point

    You agree that the Poiseuille flow for flows along or between plates applies (I prefer the two plates view, because, despite what you say, there is friction on the other side, try to push water through a serynge in the micron size)

    You agree that there is a saddle point

    You agree that there is a small flow oriented caudally, and one larger oriented rostrally.

    Therefore, you agree with all hypothesis and almost all conclusions of my model. You still disagree for the crack, that’s ok, time will tell.

    Now, what IS unpublished, I admit it, is how the vortex lifts the epiblast. I sent you the evidence you threw it to the dustbin and said « you are not in a hurry »

    If you are not in a hurry, please suspend all your pointless comments, until what you do not want even to read is submitted. Everytime you will write « there is no evidence » will be defamation. You had the evidence in hand.

    Finally, I wish to say, that, eventually, you did understand something to the model : that friction plays a role, that maybe changing the friction would make a completely different physics, and possibly, a completely different animal. That’s exactly what all this is about. Unfortunately, the 1 plate or 2 plate case make no difference (simple prefactor) and my theory stands, as it has stood against all your brutal and pitiful accusations for months

    maybe indeed, if there is more friction on the top, you make an animal more slowly, or a more elongated one, or whatever, but that’s physics. Now you know.

    You must stop, now, Vekris, it’s high time.

    Vincent Fleury

    about :
    And why you don’t just connect to Wikipedia to correct those two entries?

    I do not know how this work, but I will do it right now if I can.

  9. Well, that’s great. Correct URL 🙂 Thank you. And Thank you for adding to Wikipedia (see, it was simple, a blog is simpler).

    Now, I have a more correct description of what you think that happens at the epiblast level and the analogy with hydrodynamics.

    Doesn’t make it true, but clearer and it will be more easy to compare with experimental data.

    At least you seem to not fully support anymore the description of the « sandwich » model presented at fig. 3,4, and in text:

    We assume that the blastodisc [sic] is a composite structure, namely a “sandwich”: Extra-Cellular Matrix/ cellular layers/Extra-Cellular Matrix. This composite structure is created by apicobasal asymmetry of cells inherited from dorso-ventral anisotropy of the ovocyte. The ECM is supposed to be a strong collagenous membrane which bears most of the mechanical load.

    That’s a first step.

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