4 citations · 8 across the 19 of their papers we have counts for
6 papers · 1 filter
Spectral Asymptotics of a Singular Harmonic Oscillator with Aharonov--Bohm Flux
Bernard Helffer, Ayman Kachmar, François Nicoleau
Motivated by a recent article of R. Vanlaere (2026), we investigate the spectral asymptotics of a singular harmonic oscillator arising from the radial reduction of the magnetic Sch…
Eigenvalues of the linearized Navier-Stokes operator near locally Couette laminar flows
Yaniv Almog, Bernard Helffer
We consider the spectrum of the Orr-Sommerfeld operator, which is obtained from the linearized Navier-Stokes (LNS) operator near a laminar flow in an infinite two-dimensional chann…
A Local-to-Global Propagation Principle for Dirichlet-to-Neumann Maps
Thierry Daudé, Alberto Enciso, Bernard Helffer +2
We establish four local-to-global propagation results for Dirichlet--to--Neumann maps. Our first two results are proved in the general setting of smooth compact Riemannian manifold…
Pleijel's theorem for a class of degenerate elliptic operators
Rupert L. Frank, Bernard Helffer
We prove an asymptotic upper bound on the number of nodal domains of eigenfunctions of a class of degenerate elliptic operators. Our proof yields the same constant as in Pleijel's…
A Sharp Regularity Threshold for Uniqueness in Riemannian Calderón-type Problems
Thierry Daudé, Alberto Enciso, Bernard Helffer +2
We prove a sharp regularity threshold for uniqueness in two anisotropic Calderón-type inverse problems in dimension . The main setting is the Riemannian Schrödinger problem…
A fresh look at the Peierls-Onsager substitution
Horia D. Cornean, Bernard Helffer, Radu Purice
We formulate a general version of the Peierls-Onsager substitution for a finite family of Bloch eigenvalues under a local spectral gap hypothesis, via strongly localized tight-fram…