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991.
Joachim Toft 《Bulletin des Sciences Mathématiques》2002,126(2):115-142
We study continuity properties for a family {sp}p?1 of increasing Banach algebras under the twisted convolution, which also satisfies that a∈sp, if and only if the Weyl operator aw(x,D) is a Schatten-von Neumann operator of order p on L2. We discuss inclusion relations between the sp-spaces, Besov spaces and Sobolev spaces. We prove also a Young type result on sp for dilated convolution. As an application we prove that f(a)∈s1, when a∈s1 and f is an entire odd function. We finally apply the results on Toeplitz operators and prove that we may extend the definition for such operators. 相似文献
992.
The differential cross-sections for the emission of M shell fluorescent X-rays from Th by 5·95 keV photons at eight angles
ranging from 50° to 120° have been measured. The differential cross-section is found to decrease with increase in the emission
angle showing anisotropic spatial distribution of M shell fluorescent X-rays. The present results contradict the predictions
of the calculations of Cooper and Zare [1] that the atomic inner shell vacancy states produced in photoionization are not
aligned but confirm those of Fluggeet al [2] and Scofield [3] that the vacancy states withJ > 1/2 are aligned. The integral M shell fluorescent emission cross sections have been determined from the measured angular
distribution coefficients and compared with theoretical integral cross-sections calculated by using theoretical values of
M subshell photoionization cross-sections, fluorescence yields and coster kronig transition probabilities available in literature.
The experimental and theoretical values of integral crosssections show a reasonable agreement. 相似文献
993.
We give sufficient conditions for essential selfadjointness of operators associated with classical Dirichlet forms on Hilbert spaces and of potential perturbations of Dirichlet operators. We also study the smoothness of generalized solutions of elliptic equations corresponding to the Dirichlet operators.Supported by the Alexander von Humboldt Foundation. 相似文献
994.
W. A. Kirk 《Journal of Fixed Point Theory and Applications》2007,2(2):195-207
This is a survey of recent results on best approximation and fixed point theory in certain geodesic spaces. Some of these
results are related to fundamental fixed point theorems in topology that have been known for many years. However the metric
approach is emphasized here.
Dedicated to Edward Fadell and Albrecht Dold on the occasion of their 80th birthdays 相似文献
995.
Sr4Al14O25:RE3+(RE=Eu,Ce,Tb)中稀土离子的发光性质 总被引:4,自引:0,他引:4
采用高温固相反应合成了Sr4Al14O25:RE^3 (RE=Eu,Ce,Tb)样品,研究了其中Eu^3 ,Ce^3 和Tb^3 的光谱性质,以及Ce^3 与Tb^3 共掺时的能量传递现象;发现Eu^3 ,Ce^3 和Tb^3 占有两个格位,与Eu^2 在此基质中的情况相似;在Tb^3 的发射光谱中同时观察到了来自^5D3与^5D4的发射,表明两能级间无辐射跃迁过程不显著;Ce^3 对Tb^3 有敏化作用。 相似文献
996.
Fengde Chen Zhong Li Xiaoxing Chen Jitka Laitochová 《Journal of Computational and Applied Mathematics》2007
In this paper, we consider a modified delay differential equation model of the growth of n-species of plankton having competitive and allelopathic effects on each other. We first obtain the sufficient conditions which guarantee the permanence of the system. As a corollary, for periodic case, we obtain a set of delay-dependent condition which ensures the existence of at least one positive periodic solution of the system. After that, by means of a suitable Lyapunov functional, sufficient conditions are derived for the global attractivity of the system. For the two-dimensional case, under some suitable assumptions, we prove that one of the components will be driven to extinction while the other will stabilize at a certain solution of a logistic equation. Examples show the feasibility of the main results. 相似文献
997.
Haïm Brezis Jean Van Schaftingen 《Calculus of Variations and Partial Differential Equations》2007,30(3):369-388
We obtain boundary estimates for the gradient of solutions to elliptic systems with Dirichlet or Neumann boundary conditions
and L
1–data, under some condition on the divergence of the data. Similar boundary estimates are obtained for div–curl and Hodge
systems. 相似文献
998.
Since its introduction by Loday in 1995, with motivation from algebraic K-theory, dendriform dialgebras have been studied quite extensively with connections to several areas in Mathematics and Physics. A few more similar structures have been found recently, such as the tri-, quadri-, ennea- and octo-algebras, with increasing complexity in their constructions and properties. We consider these constructions as operads and their products and duals, in terms of generators and relations, with the goal to clarify and simplify the process of obtaining new algebra structures from known structures and from linear operators. 相似文献
999.
Lars Kadison 《Annali dell'Universita di Ferrara》2005,51(1):209-231
We reduce certain proofs in [16, 11, 12] to depth two quasibases from one side only, a minimalistic approach which leads to
a characterization of Galois extensions for finite projective bialgebroids without the Frobenius extension property. We prove
that a proper algebra extension is a leftT-Galois extension for some right finite projective left bialgebroid over some algebraR if and only if it is a left depth two and left balanced extension. Exchanging left and right in this statement, we have a
characterization of right Galois extensions for left finite projective right bialgebroids. Looking to examples of depth two,
we establish that a Hopf subalgebra is normal if and only if it is a Hopf-Galois extension. We characterize finite weak Hopf-Galois
extensions using an alternate Galois canonical mapping with several corollaries: that these are depth two and that surjectivity
of the Galois mapping implies its bijectivity.
Sunto Riduciamo alcune prove di [16,11,12] a quasibasi di profondità due da un lato solo, un approccio minimalistico che conduce ad una caratterizzazione di estensioni di Galois per bialgebroidi proietivi finiti senza la proprietà di estensione di Frobenius. Dimostriamo che un'algebra che sia un'estensione propria è un'estensioneT-Galois sinistra per qualche bialgebroide finito proiettivo a sinistra su qualche algebraR se, e solo se, è un'estensione di profondità due a sinistra e bilanciata a sinistra. Scambiando destra e sinistra nell'enunciato, otteniamo una caratterizzazione di estensioni di Galois destre per bialgebroidi finiti proiettivi a destra. Guardando ad esempi di profondità due, otteniamo che una sottoalgebra di Hopf è normale se, e solo se, è un'estensione Hopf-Galois. Caratterizziamo le estensioni Hopf-Galois deboli finite usando un'applicazione canonica di Galois alternativa ottenendo parecchi corollari: queste sono di profondità due e la suriettività dell'applicazione di Galois implica la sua biiettività.相似文献
1000.
A scheme for teleporting an arbitrary and unknown three-particle state from a sender to either one of two receivers is proposed. The quantum channel is composed of a two-particle non-maximally entangled state and two three-particle non-maximally entangled W states. An arbitrary three-particle state can be perfectly teleported probabilistically if the sender performs three generalized Bell-state measurements and sends to the two receivers the classical result of these measurements, and either one of the two receivers adopts an appropriate unitary transformation conditioned on the suitable measurement outcomes of the other receiver. All kinds of unitary transformations are given in detail. 相似文献