This paper is concerned with an extension and reinterpretation of previous results on the variational characterization of eigenvalues in gaps of the essential spectrum of self-adjoint operators. We state two general abstract results on the existence of eigenvalues in the gap and a
continuation principle. Then these results are applied to Dirac operators in order to characterize simultaneously eigenvalues corresponding to electronic and positronic bound states.
Cette revue est la version écrite d’un exposé sur quelques résultats (d’après des travaux en collaboration avec J. Dolbeault, M. Loss, G. Tarantello and A. Tertikas) concernant les propriétés de symétrie des fonctions extrémales pour les inégalités de Caffarelli-Kohn-Nirenberg
To study the asymptotic properties of entropy estimates, we use a unified expression, called the -entropy. Asymptotic distributions for these statistics are given in several cases when maximum likelihood estimators are considered, so they can be used to construct confidence intervals and to test statistical hypotheses based on one or more samples. These results can also be applied to multinomial populations.
Nous présentons dans cette note une nouvelle façon d’aborder les questions d’existence de solutions faibles pour certains problèmes d’interaction fluide-structure. Dans l’état actuel, cette approche permet de traiter le cas de solides rigides ou très faiblement déformables, immergés dans un fluide visqueux incompressible ou dans un fluide visqueux compressible dont l’évolution est isentropique.
Les équations de Dirac-Fock sont l’analogue relativiste des équations de Hartree-Fock. Elles sont utilisées dans les calculs numériques de la chimie quantique, et donnent des résultats sur les électrons dans les couches profondes des atomes lourds. Ces résultats sont en très bon accord avec les données expérimentales. Par une méthode variationnelle, nous montrons l’existence d’une infinité de solutions des équations de Dirac-Fock “sans projecteur", pour des systèmes coulombiens d’électrons dans...
We first discuss a class of inequalities of Onofri type depending on a parameter, in the two-dimensional Euclidean space. The inequality holds for radial functions if the parameter is larger than . Without symmetry assumption, it holds if and only if the parameter is in the interval .
The inequality gives us some insight on the symmetry breaking phenomenon for the extremal functions of the Caffarelli-Kohn-Nirenberg inequality, in two space dimensions. In fact, for suitable sets of parameters (asymptotically...
The purpose of this paper is to study a model coupling an incompressible viscous fiuid with an elastic structure in a bounded container. We prove the existence of weak solutions à la Leray as long as no collisions occur.
A non-homogeneous Hardy-like inequality has recently been found to be closely related to the knowledge of the lowest eigenvalue of a large class of Dirac operators in the gap of their continuous spectrum.
K. M. Wong and S. Chen [9] analyzed the Shannon entropy of a sequence of random variables under order restrictions. Using -entropies, I. J. Taneja [8], these results are generalized. Upper and lower bounds to the entropy reduction when the sequence is ordered and conditions under which they are achieved are derived. Theorems are presented showing the difference between the average entropy of the individual order statistics and the entropy of a member of the original independent identically distributed...
En esta comunicación se establece una medida de la entropía contenida en un proceso puntual mediante el concepto de entropía de orden α y tipo β introducida por Sharma and Mittal (1975); quedando, de este modo, generalizada la entropía de McFadden. Una vez que se estudian las propiedades relativas a la tasa de cambio de la Entropía, se demuestra que el proceso de Poisson es el de Entropía máxima dentro de la clase de los procesos puntuales estacionarios.
The main goal of this paper is to investigate how to estimate sampling design variances of modelbased and model-assisted small area estimators in a complex survey sampling setup. For this purpose the Spanish Labour Force Survey is considered. Sample and aggregated data are taken from the Canary Islands in the second trimester of 2003 in order to obtain some small area estimators of ILO unemployment totals. Several problems arising from the application of standard small area estimation procedures...
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