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Current Colloquia & Seminars

  1. Euler/Navier Stokes (Part 1): Vortex dynamics and relative equilibria

    Location: MSRI: Online/Virtual
    Speakers: Taoufik Hmidi (Université de Rennes I)

    To participate in this seminar, please register here: https://www.msri.org/seminars/25657

    Abstract: In the first part of the talk I will give a general survey on vortex motion in nonlinear transport models appearing in geophysical flows. Particular interest will concern the construction of periodic solutions for Euler and shallow water quasi-geostrophic equations SWQG and to exhibit the main feature  of  their bifurcation diagrams. In the last part of the talk I will discuss the existence of a Cantor family of  quasi-periodic solutions to SWQG equation using KAM theory. 

    Updated on Feb 17, 2021 07:22 AM PST
  2. Euler/Navier Stokes (Part 2): Geometric constraints on the blowup of solutions of the Navier-Stokes equation

    Location: MSRI: Online/Virtual
    Speakers: Evan Miller (McMaster University)

    To participate in this seminar, please register here: https://www.msri.org/seminars/25657

    Abstract: In this talk, I will discuss several regularity criteria that provide geometric constraints on the possible finite-time blowup of solutions of the Navier-Stokes equation. This approach, based on the strain formulation of the Navier-Stokes regularity problem, not only gives geometric criteria for blowup in terms of the eigenvalues of the strain matrix, but also improves previous geometric regularity criteria involving the vorticity. Finally, I will discuss finite-time blowup for a model equation for the self-amplification of strain that respects these geometric constraints.


    Updated on Feb 17, 2021 07:23 AM PST
  3. Fellowship of the Ring, National Seminar: How short can a module of finite projective dimension be?

    Location: MSRI: Online/Virtual
    Speakers: Mark Walker (University of Nebraska)

    To attend this seminar, you must register in advance, by clicking HERE.

    Abstract: This is joint work with Srikanth Iyengar and Linquan Ma. I will discuss the question:

    For a given Cohen-Macaulay local ring R, what is the minimum non-zero value of length(M), where M ranges over those R-modules having finite projective dimension?

    In investigating this question, one is quickly led to conjecture that the answer is e(R), the Hilbert-Samuel multiplicity of R. It turns out that this can be established for rings having Ulrich modules, or, more generally, lim Ulrich sequences of modules, with certain properties. Moreover, there is a related conjecture concerning length(M) and the Betti numbers of M, and a conjecture concerning the Dutta multiplicity of M, which can also be established when certain Ulrich modules (or lim Ulrich sequences) exist.

    Updated on Feb 22, 2021 07:13 AM PST