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The square root of the heat operator $\sqrt{\partial_t-\Delta}$, can be realized as the Dirichlet to Neumann map of the heat extension of data on $\mathbb R^{n+1}$ to $\mathbb R^{n+2}_+$. In this note we obtain similar characterizations for…

Analysis of PDEs · Mathematics 2015-11-11 K. Nyström , O. Sande

For a class of non-selfadjoint $h$--pseudodifferential operators with double characteristics, we give a precise description of the spectrum and establish accurate semiclassical resolvent estimates in a neighborhood of the origin.…

Analysis of PDEs · Mathematics 2011-05-25 Michael Hitrik , Karel Pravda-Starov

We prove qualitatively sharp heat kernel bounds in the setting of Fourier-Bessel expansions when the associated type parameter $\nu$ is half-integer. Moreover, still for half-integer $\nu$, we also obtain sharp estimates of all kernels…

Classical Analysis and ODEs · Mathematics 2014-10-29 Adam Nowak , Luz Roncal

We consider a class of fourth order uniformly elliptic operators in planar Euclidean domains and study the associated heat kernel. For operators with $L^{\infty}$ coefficients we obtain Gaussian estimates with best constants, while for…

Analysis of PDEs · Mathematics 2018-07-04 Gerassimos Barbatis , Panagiotis Branikas

We obtain heat kernel estimates for a class of fourth order non-uniformly elliptic operators in two dimensions. Contrary to existing results, the operators considered have symbols that are not strongly convex. This rises certain…

Analysis of PDEs · Mathematics 2022-11-22 Gerassimos Barbatis , Panagiotis Branikas

We prove global subelliptic estimates for systems of quadratic differential operators. Quadratic differential operators are operators defined in the Weyl quantization by complex-valued quadratic symbols. In a previous work, we pointed out…

Analysis of PDEs · Mathematics 2010-01-13 Karel Pravda-Starov

We obtain pointwise lower bounds for heat kernels of higher order differential operators with Dirichlet boundary conditions on bounded domains in $\R^N$. The bounds exhibit explicitly the nature of the spatial decay of the heat kernel close…

Spectral Theory · Mathematics 2011-10-18 Narinder S Claire

Let $L = -{\rm div}( A(x) \cdot \nabla ) + V(x)$ be a second-order uniformly elliptic operator on $\mathbb{ R }^{n}$ $(n\geq 3)$, where $A(x)$ is a real symmetric matrix satisfying standard ellipticity conditions, and $V$ is a nonnegative…

Functional Analysis · Mathematics 2025-05-09 Honglei Shi , Pengtao Li , Kai Zhao

In this article, using methods from geometric analysis and theory of heat kernels, we derive qualitative estimates of automorphic cusp forms defined over quaternion algebras. Using which, we prove an average version of the holomorphic QUE…

Number Theory · Mathematics 2017-08-22 Anilatmaja Aryasomayajula , Baskar Balasubramanyam

The covariant technique for calculating the heat kernel asymptotic expansion for an elliptic differential second order operator is generalized to manifolds with boundary. The first boundary coefficients of the asymptotic expansion which are…

High Energy Physics - Theory · Physics 2008-11-26 Ivan G. Avramidi

We find a Gaussian off-diagonal heat kernel estimate for uniformly elliptic operators with measurable coefficients acting on regions $\Omega\subseteq\real^N$, where the order $2m$ of the operator satisfies $N<2m$. The estimate is expressed…

Spectral Theory · Mathematics 2007-05-23 Mark P. Owen

Under structural conditions which are almost optimal, we derive a quantitative version of boundary estimate then prove existence of solutions to Dirichlet problem for a class of fully nonlinear elliptic equations on Hermitian manifolds.

Analysis of PDEs · Mathematics 2021-06-29 Rirong Yuan

In this article we study some Kramers-Fokker-Planck operators with a polynomial potential $V(q)$ of degree greater than two having quadratic limiting behavior. This work provides an accurate global subelliptic estimate for KFP operators…

Analysis of PDEs · Mathematics 2019-05-29 Mona Ben Said

A representation theorem for non-semibounded Hermitian quadratic forms in terms of a (non-semibounded) self-adjoint operator is proven. The main assumptions are closability of the Hermitian quadratic form, the direct integral structure of…

Functional Analysis · Mathematics 2022-07-11 Alberto Ibort , José G. Llavona , Fernando Lledó , Juan Manuel Pérez-Pardo

For a class of non-selfadjoint semiclassical pseudodifferential operators with double characteristics, we study bounds for resolvents and estimates for low lying eigenvalues. Specifically, assuming that the quadratic approximations of the…

Analysis of PDEs · Mathematics 2009-02-23 Michael Hitrik , Karel Pravda-Starov

We consider the standard thermodynamic processes with constraints, but with additional uncertainty about the control parameters. Motivated by inductive reasoning, we assign prior distribution that provides a rational guess about likely…

Statistical Mechanics · Physics 2014-04-03 Preety Aneja , Ramandeep S. Johal

This work is concerned with the development of a space-time adaptive numerical method, based on a rigorous a posteriori error bound, for the semilinear heat equation with a general local Lipschitz reaction term whose solution may blow-up in…

Numerical Analysis · Mathematics 2018-02-23 Irene Kyza , Stephen Metcalfe

We develop the machinery of boundary triplets for one-dimensional operators generated by formally self-adjoint quasi-differential expression of arbitrary order on a finite interval. The technique are then used to describe all maximal…

Functional Analysis · Mathematics 2013-04-25 Andrii Goriunov , Vladimir Mikhailets , Konstantin Pankrashkin

The present work is devoted to the problem of boundary stabilization of the semilinear 1-D heat equation with nonlocal boundary conditions. The stabilizing controller is finite-dimensional, linear, given in an explicit form, involving only…

Optimization and Control · Mathematics 2020-04-21 Ionut Munteanu

Some mathematical models of applied problems lead to the need of solving boundary value problems with a fractional power of an elliptic operator. In a number of works, approximations of such a nonlocal operator are constructed on the basis…

Numerical Analysis · Computer Science 2019-05-28 Petr N. Vabishchevich