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The second eigenvalue of the Robin Laplacian is shown to be maximal for the disk among simply-connected planar domains of fixed area when the Robin parameter is scaled by perimeter in the form $\alpha/L(\Omega)$, and $\alpha$ lies between…

Spectral Theory · Mathematics 2019-03-05 Pedro Freitas , Richard S. Laugesen

Let $D \subset \mathbb{R}^d$ be a bounded, connected domain with smooth boundary and let $-\Delta u = \mu_1 u$ be the first nontrivial eigenfunction of the Laplace operator with Neumann boundary conditions. We prove $$ \max_{x \in D} ~u(x)…

Analysis of PDEs · Mathematics 2021-10-11 Stefan Steinerberger

We obtain results for the spectral optimisation of Neumann eigenvalues on rectangles in $\mathbb{R}^2$ with a measure or perimeter constraint. We show that the rectangle with measure $1$ which maximises the $k$'th Neumann eigenvalue…

Spectral Theory · Mathematics 2018-05-16 Michiel van den Berg , Dorin Bucur , Katie Gittins

This article is devoted the semiclassical spectral analysis of the Neumann magnetic Laplacian on a smooth bounded domain in three dimensions. Under a generic assumption on the variable magnetic field (involving a localization of the…

Spectral Theory · Mathematics 2023-07-03 Khaled Abou Alfa , Maha Aafarani , Frédéric Hérau , Nicolas Raymond

In quantum theory on curved backgrounds, Heisenberg's uncertainty principle is usually discussed in terms of ensemble variances and flat-space commutators. Here we take a different, preparation-based viewpoint tailored to sharp position…

General Relativity and Quantum Cosmology · Physics 2026-02-05 Thomas Schürmann

The aim of this article is to provide a simple and unified way to obtain the sharp upper bounds of nodal sets of eigenfunctions for different types of eigenvalue problems on real analytic domains. The examples include biharmonic Steklov…

Analysis of PDEs · Mathematics 2020-10-08 Fanghua Lin , Jiuyi Zhu

The paper deals with the homogenization of a magneto-elastodynamics equation satisfied by the displacement $u\_\varepsilon$ of an elastic body which is subjected to an oscillating magnetic field $B\_\varepsilon$ generating the Lorentz force…

Analysis of PDEs · Mathematics 2020-01-28 Marc Briane , Juan Casado-Diaz

For smooth bounded pseudoconvex domains in $mathbb{C}^{2}$, we provide geometric conditions on (the points of infinite type in) the boundary which imply compactness of the $\bar{\partial}$-Neumann operator. It is noteworthy that the proof…

Complex Variables · Mathematics 2007-05-23 Emil J. Straube

In order to generate a desired Kelvin (magnetic) force in a target subdomain moving along a prescribed trajectory, we propose a minimization problem with a tracking type cost functional. We use the so-called dipole approximation to realize…

Optimization and Control · Mathematics 2016-12-26 Harbir Antil , Ricardo H. Nochetto , Pablo Venegas

It is shown that in strongly magnetized neutron stars, there exist upper limits of magnetic field strength, beyond which the self energies for both neutron and proton components of neutron star matter become complex in nature. As a…

Astrophysics · Physics 2008-11-26 Somenath Chakrabarty

In this paper we consider magnetic Schroedinger operators on the two-dimensional unit disk with a radially symmetric magnetic field which explodes to infinity at the boundary. We prove a bound for the eigenvalue moments and a bound for the…

Spectral Theory · Mathematics 2020-05-20 Diana Barseghyan , Baruch Schneider

In a very interesting paper, Andr\'easson has recently proved that the gravitational mass of a spherically symmetric compact object of radius $R$ and electric charge $Q$ is bounded from above by the relation…

General Relativity and Quantum Cosmology · Physics 2019-04-03 Shahar Hod

In this work, optimal rigidity results for eigenvalues on K\"ahler manifolds with positive Ricci lower bound are established. More precisely, for those K\"ahler manifolds whose first eigenvalue agrees with the Ricci lower bound, we show…

Differential Geometry · Mathematics 2024-12-24 Jianchun Chu , Feng Wang , Kewei Zhang

We derive upper bounds to free-space concentration of electromagnetic waves, mapping out the limits to maximum intensity for any spot size and optical beam-shaping device. For sub-diffraction-limited optical beams, our bounds suggest the…

Optics · Physics 2020-07-08 Hyungki Shim , Haejun Chung , Owen D. Miller

In this paper we obtain several results concerning the optimization of higher Steklov eigenvalues both in two and higher dimensional cases. We first show that the normalized (by boundary length) $k$-th Steklov eigenvalue on the disk is not…

Differential Geometry · Mathematics 2019-10-09 Ailana Fraser , Richard Schoen

In this paper we study extremal behaviors of the mean to max ratio of the $p$-torsion function with respect to the geometry of the domain. For $p$ larger than the dimension of the space $N$, we prove that the upper bound is uniformly below…

Analysis of PDEs · Mathematics 2023-01-24 Luca Briani , Dorin Bucur

In 1996 Erdoes showed that among planar domains of fixed area, the smallest principal eigenvalue of the Dirichlet Laplacian with a constant magnetic field is uniquely achieved on the disk. We establish a quantitative version of this…

Spectral Theory · Mathematics 2023-05-15 Rohan Ghanta , Lukas Junge , Leo Morin

The magnetic field of a homogeneously magnetized cylindrical tile geometry, i.e. an angular section of a finite hollow cylinder, is found. The field is expressed as the product between a tensor field describing the geometrical part of the…

Computational Engineering, Finance, and Science · Computer Science 2020-04-27 K. K. Nielsen , R. Bjørk

By considering a certain univalent function in the open unit disk U, that maps U onto a strip domain, we introduce a new class of analytic and close-to-convex functions by means of a certain non-homogeneous Cauchy-Euler-type differential…

Complex Variables · Mathematics 2019-02-19 Serap Bulut

We consider the motion of electrons confined to a two dimensional plane with an externally applied perpendicular inhomogeneous magnetic field, both with and without a Coulomb potential. We find that as long as the magnetic field is…

Mesoscale and Nanoscale Physics · Physics 2016-08-05 C. A. Downing , M. E. Portnoi