Title:  On rotating star solutions to the Euler-Poisson equations

Abstract:  The Euler-Poisson equations are used in astrophysics to model the motion of gaseous stars. The so called rotating star solutions are density functions that satisfy the Euler- Poisson equations with a prescribed angular velocity configuration. They are one of the many efforts to try to characterize the equilibrium shape of fluids under self gravitation. Auchmuty and Beals in 1971 found a family of rotating star solutions by solving a variational free boundary problem. Recent interests in the astrophysics community require one to extend the picture to include a solid core together with its gravitational fields. In this talk, we will discuss an extension of the Auchmuty and Beals result in this direction. If time permits, we will also explore results on non-existence of solutions for fast rotation, and discuss the effects of gas equation of state.

Title:  A scattering map in two dimensions

Abstract:  We consider the scattering map introduced by Beals and Coifman and Fokas and Ablowitz that may be used to transform one of the Davey-Stewartson equations to a linear evolution. We give mapping properties of this map on weighted L 2 Sobolev spaces that mimic well-known properties of the Fourier transform. This is joint work with N. Serpico, P. Perry and K. Ott.

Title:  Uniform estimates in homogenization and applications

Abstract:  In a seminal paper of 1987, M. Avellaneda and F.H. Lin have introduced a powerfull method to show uniform Hölder and Lipschitz estimates for elliptic systems with oscillating coefficients. In this talk, I will investigate some consequences of these estimates for the large scale behavior of potentials and the asymptotics of boundary layers in homogenization. I will also address a generalization of the Lipschitz estimate to domains with oscillating boundary. The latter is a joint work with C. Kenig.

Title:  Eigenvalue Multiplicities of the Hodge Laplacian on Coexact 2-Forms for Generic Metrics on 5-Manifolds

Abstract:  In 1976, Uhlenbeck used transversality theory to show that on a closed Riemannian manifold, the eigenvalues of the Laplace-Beltrami operator are all simple for a residual set of C^r metrics. In 2012, Enciso and Peralta-Salas established an analogue of Uhlenbeck's theorem for differential forms, showing that on a closed 3-manifold, there exists a residual set of C^r metrics such that the nonzero eigenvalues of the Hodge Laplacian on k forms are all simple.  We continue to address the question of whether Uhlenbeck's theorem can be extended to differential forms by proving that for a residual set of C^r metrics, the nonzero eigenvalues of the Hodge Laplacian acting on coexact 2-forms on a closed 5-manifold have multiplicity 2.  We structure our argument around a study of the Beltrami operator, using techniques from perturbation theory to show that the Beltrami operator has only simple eigenvalues for a residual set of metrics.  We further establish even eigenvalue multiplicities for the Hodge Laplacian acting on coexact k-forms in the more general setting n=4m+1 and k=2m.

Title:  DeBranges' Proof of the Bieberbach Conjecture

Abstract:  See Bulletin Board on 7th Floor- POT for abstract

Title:  Sub-Exponential Decay Estimates on Trace Norms of Localized Functions of Schrodinger Operators

Abstract:  In 1973, Combes and Thomas discovered a general technique for showing exponential decay of eigenfunctions. The technique involved proving the exponential decay of the resolvent of the Schrodinger operator localized between two distant regions. Since then, the technique has been applied to several types of Schrodinger operators. Recent work has also shown the Combes–Thomas method works well with trace class and Hilbert–Schmidt type operators. In this talk, we build on those results by applying the Combes–Thomas method in the trace, Hilbert–Schmidt, and other trace-type norms to prove sub-exponential decay estimates on functions of Schrodinger operators localized between two distant regions.

Title:  On the ground state of the magnetic Laplacian in corner domains

Abstract:  I will present recent results about the first eigenvalue of the magnetic Laplacian in general 3D-corner domains with Neumann boundary condition in the semi-classical limit.  The use of singular chains show that the asymptotics of the first eigenvalue is governed by a hierarchy of model problems on the tangent cones of the domain. We provide estimations of the remainder depending on the geometry and the variations of the magnetic field. This is a joint work with V. Bonnaillie-Nol and M. Dauge.

Title:  Compressible Navier-Stokes equations with temperature dependent dissipation

Abstract:  From its physical origin, the viscosity and heat conductivity coe!cients in compressible fluids depend on absolute temperature through power laws. The mathematical theory on the well-posedness and regularity on this setting is widely open. I will report some recent progress on this direction, with emphasis on the lower bound of temperature, and global existence of solutions in one or multiple dimensions. The relation between thermodynamics laws and Naiver-Stokes equations will also be discussed. This talk is based on joint works with Weizhe Zhang.