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951.
Letn2. The authors establish theL
2(
n
)-boundedness of singular integrals with variable rough Calderón-Zygmund kernels associated to surfaces satisfying some conditions.The research is supported in part by the NNSF and the SEDF of China. 相似文献
952.
LetT B(H) be a bounded linear operator on a complex Hilbert spaceH. Let 0 (T) be an isolated point of (T) and let
be the Riesz idempotent for 0. In this paper, we prove that ifT isp-hyponormal or log-hyponormal, thenE is self-adjoint andE
H=ker(H–0)=ker(H–0
*.This research was supported by Grant-in-Aid Research 1 No. 12640187. 相似文献
953.
Yurij M. Berezansky 《Integral Equations and Operator Theory》2002,44(3):255-289
The article is devoted to two generalizations of the classical power moment problem, namely: 1) instead of representing the moment sequence by
n
, a representation by polynomialsP
n
(), 1, connected with a Jacobi matrix, appears; 2) in the representation, instead of
n
, the expression n
figures, where is a real generalized function (i.e., we investigate some infinite-dimensional moment problem).The work is partially supported by the DFG, Project 436 UKR 113/39/0 and by the CRDF, Project UM1-2090. 相似文献
954.
The sub-optimal Hankel norm approximation problem is solved under the assumptions that the system is given in terms of a triple of operators (–A, B, C), where–A is the infinitesimal generator of an exponentially stable, analytic semigroup on the Hilbert spaceZ,B L (
m
,Z
where –1<0,C L is obtained in terms of the system parameters–A, B, C. (Z,
p
), and the system is approximately controllable. An explicit parameterization of all solutions 相似文献
955.
Let ƒ and g be real-analytic functions near the origin in ℝ2. Given 1 < p < ∞, we obtain a characterization of the set of positive numbers ∈ and δ that ensures
for some small neighborhood K of the origin. A notion of stability is introduced in relation to Ap weights and a counterexample is presented to show that the two-dimensional weighted problem, unlike its analog in dimension
one, is not stable. 相似文献
956.
We present a characterization of the open unit ball in a separable infinite dimensional Hilbert space by the property of automorphism
orbits among the domains that are not necessarily bounded. This generalizes the recent work of Kim and Krantz [6]. Key new
features of this article include: a lower bound estimate of the Kobayashi metric and distance near a pluri-subharmonic peak
boundary point of the domains in Banach spaces, an effective localization argument, and an improvement of weak-type convergence
of sequences of biholomorphic mappings of domains in Banach spaces. 相似文献
957.
958.
N.J. Curro 《Journal of Physics and Chemistry of Solids》2002,63(12):2181-2185
We discuss the crossover of the form of the Cu Nuclear magnetic resonance (NMR) spin echo decay at the onset of Cu wipeout in lanthanum cuprates. Experimentally, the echo decay undergoes a crossover from Gaussian to exponential form below the temperature where the Cu NMR intensity drops. The wipeout and the change in behavior both arise because the nuclei experience spatially inhomogeneous spin fluctuations at low temperatures. We argue that regions where the spin fluctuations remain fast are localized on length scales of order 1-2 lattice spacings. The inhomogeneity is characterized by the local activation energy Ea(r); we estimate the functional form of Ea(r) for points where Ea>(r)∼0. 相似文献
959.
In a category with injective hulls and a cogenerator, the embeddings into injective hulls can never form a natural transformation,
unless all objects are injective. In particular, assigning to a field its algebraic closure, to a poset or Boolean algebra
its Mac-Neille completion, and to an R-module its injective envelope is not functorial, if one wants the respective embeddings to form a natural transformation.
Received January 21, 2000; accepted in final form August 10, 2001.
RID="h1"
RID="h2"
RID="h3"
ID="h1"The hospitality of York University is gratefully acknowledged by the first author.
ID="h2"Third author partially supported by the Grant Agency of the Czech Republic under Grant no. 201/99/0310, and the hospitality
of York University is also acknowledged.
ID="h3"Partial financial assistance by the Natural Sciences and Engineering Councel of Canada is acknowledged by the fourth
author. 相似文献
960.