Weak Type Endpoint Estimates for Multilinear θ-type Calderon-Zygmund Operators

In this paper, the author discusses the multilinear singular integrals with certain θ-type Calderdn- Zygmund operators and obtain the boundedness from weak H^1 （R^n） to weak L^1 （R^n）.     

Absolutely Continuous Spectrum for Random Schrödinger Operators on Tree-Strips of Finite Cone Type

A tree-strip of finite cone type is the product of a tree of finite cone type with a finite set. We consider random Schrödinger operators on these tree-strips, similar to the Anderson model. We prove that for small disorder, the spectrum is almost surely, purely, absolutely continuous in a certain set.     

Anderson Localization for Time Periodic Random Schrödinger Operators

Abstract

We prove that at large disorder, Anderson localization in Z ^d is stable under localized time-periodic perturbations by proving that the associated quasi-energy operator has pure point spectrum. The formulation of this problem is motivated by questions of Anderson localization for non-linear Schrödinger equations.     

Error Estimates for Orthogonal Matching Pursuit and?Random Dictionaries

In this paper we investigate the efficiency of the Orthogonal Matching Pursuit algorithm (OMP) for random dictionaries. We concentrate on dictionaries satisfying the Restricted Isometry Property. We also introduce a stronger Homogenous Restricted Isometry Property which we show is satisfied with overwhelming probability for random dictionaries used in compressed sensing. For these dictionaries we obtain upper estimates for the error of approximation by OMP in terms of the error of the best n-term approximation (Lebesgue-type inequalities). We also present and discuss some open problems about OMP. This is a development of recent results obtained by D.L. Donoho, M. Elad and V.N. Temlyakov.     

Musielak-Orlicz-Bumps and Bloom Type Estimates for Commutators of Calderón-Zygmund and Fractional Integral Operators on Generalized Zygmund Spaces Via Sparse Operators

Analysis Mathematica - We study continuity properties for commutators of Calderón-Zygmund and fractional integral operators between generalized Zygmund spaces of L log L type, in the variable...     

Lifshits Tails for Random Schrödinger Operators with Nonsign Definite Potentials

This paper is devoted to the study of Lifshits tails for random Schr?dinger operator acting on of the form , where H ₀ is a -periodic Schr?dinger operator, λ is a positive coupling constant, are i.i.d and bounded random variables and V is the single site potential with changing sign. We prove that, in the weak disorder regime, at an open band edge, a true Lifshits tail for the random Schr?dinger operator occurs under a certain set of conditions on H ₀ and on V. Submitted: April 17, 2007. Accepted: December 13, 2007.     

Some Estimates of Higher Order Riesz Transform Related to Schrödinger Type Operators

In this paper we consider the Schrödinger type operators \(H_2=(-\Delta)^2 +V^2\), where the nonnegative potential V belongs to the reverse Hölder class \(B_{q_{_1}}\) for \(q_{_1}\geq \frac{n}{2}, n\geq 5\). The L ^p and weak type (1, 1) estimates of higher order Riesz transform \(\nabla^2H^{-\frac{1}{2}}_2 \) related to Schrödinger type operators H ₂ are obtained. In particular, \(\nabla^2H^{-\frac{1}{2}}_2 \) is a Calderón-Zygmund operator if V?∈?B _2n or \(V\in B_\frac{n}{2}\) and there exists a constant C such that V(x)?≤?Cm(x,V)².     

L~p Estimates for Hyperbolic Singular Integral Operators

In this paper, we prove Lp-boundedness of hyperbolic singular integral operators for kernels satisfying weakened regularity conditions, where 1相似文献   

Weak Type Estimates for a Kind of Singular Integral Operators Along Radial Surfaces

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Multi-weight, Weighted Weak Type Estimates for the Multilinear Calderón-Zygmund Operators

Let m be an integer and T be an m-linear Calderón-Zygmund operator, u, v1,..., vm be weights. In this paper, the authors give some sufficient conditions on the weights (u, vk) with 1 ≤ k ≤ m, such that T is bounded from Lp1(Rn, v1) × ··· × Lpm(Rn, vm) to Lp,∞(Rn, u).     

Remarks on the Cwikel–Lieb–Rozenblum and?Lieb–Thirring Estimates for Schr?dinger Operators on?Riemannian Manifolds

Let M be a general complete Riemannian manifold and consider a Schr?dinger operator −Δ+V on L ²(M). We prove Cwikel–Lieb–Rozenblum as well as Lieb–Thirring type estimates for −Δ+V. These estimates are given in terms of the potential and the heat kernel of the Laplacian on the manifold. Some of our results hold also for Schr?dinger operators with complex-valued potentials.     

New Korovkin Type Theorem for Non-Tensor Meyer–König and Zeller Operators

In this paper, we introduce a certain class of linear positive operators via a generating function, which includes the non-tensor MKZ operators and their non-trivial extension. In investigating the approximation properties, we prove a new Korovkin type approximation theorem by using appropriate test functions. We compute the rate of convergence of these operators by means of the modulus of continuity and the elements of modified Lipschitz class functions. Furthermore, we give functional partial differential equations for this class. Using the corresponding equations, we calculate the first few moments of the non-tensor MKZ operators and investigate their approximation properties. Finally, we state the multivariate versions of the results and obtain the convergence properties of the multivariate Meyer–König and Zeller operators.     

Weak-type Endpoint Estimates for Multilinear Singular Integral Operators

In this paper, the authors discuss a class of multilinear singular integrals and obtain that the operators are bounded from H^1(R^n) to weak L^1(R^n). Using this result, we can directly prove a main theorem in [5].     

Integrated Density of States for Ergodic Random Schrödinger Operators on Manifolds

We consider the Riemannian universal covering of a compact manifold M = X/ and assume that is amenable. We show the existence of a (nonrandom) integrated density of states for an ergodic random family of Schrödinger operators on X.     

Absence of Continuous Spectral Types for Certain Non-Stationary Random Schrödinger Operators

We consider continuum random Schrödinger operators of the type H = – + V₀ + V with a deterministic background potential V₀. We establish criteria for the absence of continuous and absolutely continuous spectrum, respectively, outside the spectrum of – + V₀. The models we treat include random surface potentials as well as sparse or slowly decaying random potentials. In particular, we establish absence of absolutely continuous surface spectrum for random potentials supported near a one-dimensional surface (random tube) in arbitrary dimension.submitted 07/04/04, accepted 19/08/04     

Admissibility for Nonhomogeneous Linear Estimates on Multivariate Random Regression Coefficients and Parameters

61..IntroductionLetA,BaretwomatriceslthesignA>odenotesthatAisanon-negativedefinitesquarematrixFA>BdenotesA-B>OIA>odenotesthatAisaPoSitivedefinitesquarematrix;A>BdenotesA-B>OFp(A)denotesthelinearspaceextendedbycolumnvectorsofAFA denoteSMcore-PenrosegeneralinversionofA,i.e.A satisfies:AA A=A,A AA =A ,A AandAA botharesymmetriclA-denotesthesignu-"generalinversionofA,i.e.A-satisfies:AA-A=A3Adenotestherow-drawingstraightvectorofA;A@BdenotestheKrcrneckerpreductofAandB3tr(A)denot…     

Heat Kernel Estimates for Schrödinger Operators on Exterior Domains with Robin Boundary Conditions

We study Schrödinger operators with Robin boundary conditions on exterior domains in ? ^d . We prove sharp point-wise estimates for the associated semigroups which show, in particular, how the boundary conditions affect the time decay of the heat kernel in dimensions one and two. Applications to spectral estimates are discussed as well.     

Hardy Type Estimates for Riesz Transforms Associated with Schrdinger Operators on the Heisenberg Group

Let Hnbe the Heisenberg group and Q=2n +2 be its homogeneous dimension. In this paper, we consider the Schrdinger operator-?Hn+V, where ?Hn is the sub-Laplacian and V is the nonnegative potential belonging to the reverse Ho ¨lder class Bq1 for q1≥ Q/2. We show that the operators T1= V(-?Hn +V)-1 and T2=V1/2(-?Hn +V)-1/2 are both bounded from H1L(Hn) into L1(Hn). Our results are also valid on the stratified Lie group.