Department of

Mathematics


Seminar Calendar
for Harmonic Analysis and Differential Equations Seminar events the year of Tuesday, February 19, 2019.

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More information on this calendar program is available.
Questions regarding events or the calendar should be directed to Tori Corkery.
     January 2019          February 2019            March 2019     
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Tuesday, January 22, 2019

1:00 pm in 347 Altgeld Hall,Tuesday, January 22, 2019

Singular limits of sign-changing weighted eigenproblems

Derek Kielty   [email] (Illinois Math)

Abstract: Eigenvalue problems with positive weights are related to heat flow and wave propagation in inhomogeneous media. Sign-changing weights have ecological interpretations, and generate spectra that accumulate at both positive and negative infinity. This talk will discuss recent results on limits of such eigenvalue problems when a negative portion of the weight is made arbitrarily large.

Tuesday, March 19, 2019

1:00 pm in 347 Altgeld Hall,Tuesday, March 19, 2019

The Steklov and Laplacian spectra of Riemannian manifolds with boundary

Alexandre Girouard   [email] (Université Laval)

Abstract: The Dirichlet-to-Neumann map is a first order pseudodifferential operator acting on the smooth functions of the boundary of a compact Riemannian manifold M. Its spectrum is known as the Steklov spectrum of M. The asymptotic behaviour (as j tends to infinity) of the Steklov eigenvalues s_j is determined by the geometry of the boundary of M. Neverthless, each individual eigenvalue can become arbitrarily big if the Riemannian metric is perturbed adequately. This can be achieved while keeping the geometry of the boundary unchanged, but it requires wild perturbations in arbitrarily small neighborhoods of the boundary. In recent work with Bruno Colbois and Asma Hassannezhad, we impose constraints on the geometry of M on and near its boundary. This allows the comparison of each Steklov eigenvalue s_j with the corresponding eigenvalues l_j of the Laplace operator acting on the boundary. This control is uniform in the index j. The proof is based on a generalized Pohozaev identity and on comparison results for the principal curvatures of hypersurfaces that are parallel to the boundary.

Tuesday, August 27, 2019

1:00 pm in Altgeld Hall,Tuesday, August 27, 2019

To Be Announced

Stathis Charalampidis