816 research outputs found
Decomposable symmetric mappings between infinite-dimensional spaces
Decomposable mappings from the space of symmetric k-fold tensors over E, OĂs,kE, to the space of k-fold tensors over F, OĂs,kF, are those linear operators which map nonzero decomposable elements to nonzero decomposable elements. We prove that any decomposable mapping is induced by an injective linear operator between the spaces on which the tensors are defined. Moreover, if the decomposable mapping belongs to a given operator ideal, then so does its inducing operator. This result allows us to classify injective linear operators between spaces of homogeneous approximable polynomials and between spaces of nuclear polynomials which map rank-1 polynomials to rank-1 polynomials. © 2007 Institut Mittag-Leffler.Fil:Lassalle, S. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina
Pratiques d'Ă©levage dans les exploitations bovines allaitantes conduites sur pĂąturage dans les Hauts de la RĂ©union
Dans les Hauts de la RĂ©union, lâĂ©levage bovin constitue la principale activitĂ© agricole. LâĂ©levage naisseur «professionnel» reprĂ©sente 8828 vaches mĂšres pour 497 exploitations. Ce sont des exploitations de taille modeste (18 vaches mĂšres en moyenne) dont les performances animales sont en-deçà de leurs homologues mĂ©tropolitaines. Lâobjectif de lâĂ©tude est dâanalyser les pratiques des Ă©leveurs naisseurs et dâen faire le lien avec les performances obtenues afin dâidentifier des voies dâamĂ©lioration potentielles. Pour cela, 10 Ă©leveurs ont fait lâobjet dâun suivi de 1999 Ă 2002, qui Ă©tait fondĂ© sur lâĂ©valuation des performances des animaux et sur lâenregistrement des pratiques des Ă©leveurs en particularisant lâallotement, la gestion du pĂąturage et la complĂ©mentation alimentaire. Cet article montre que les pratiques sont variĂ©es et conditionnĂ©es par des objectifs de production diffĂ©rents: stratĂ©gies de maximisation des performances ou du chargement, simplification de la conduite.Cattle farming is the main agricultural activity in the Highlands of the Reunion Island. "Professional" suckling farming represents 8828 cows for 497 farms. They are modest sized farms (18 cows on the average) whose animal performances are lower than their metropolitan counterparts. The aim of the study was to analyse the practices of the suckling farmers with the purpose of improving their management. We carried out herd monitoring on 10 farms from 1999 to 2002 within this framework. This monitoring was based on the measurement of animal performances and on the recording of the farmers' practices in terms of livestock and grazing management. This article presents the analysis carried out on 3 categories of practices: the allotment, grazing management and supplementation. There are various practices underlain by different socioeconomic objectives. Thus, strategies can be founded on the maximisation of the animal performances, the stocking rate or simplification of the management
On Poincare and logarithmic Sobolev inequalities for a class of singular Gibbs measures
This note, mostly expository, is devoted to Poincar{\'e} and log-Sobolev
inequalities for a class of Boltzmann-Gibbs measures with singular interaction.
Such measures allow to model one-dimensional particles with confinement and
singular pair interaction. The functional inequalities come from convexity. We
prove and characterize optimality in the case of quadratic confinement via a
factorization of the measure. This optimality phenomenon holds for all beta
Hermite ensembles including the Gaussian unitary ensemble, a famous exactly
solvable model of random matrix theory. We further explore exact solvability by
reviewing the relation to Dyson-Ornstein-Uhlenbeck diffusion dynamics admitting
the Hermite-Lassalle orthogonal polynomials as a complete set of
eigenfunctions. We also discuss the consequence of the log-Sobolev inequality
in terms of concentration of measure for Lipschitz functions such as maxima and
linear statistics.Comment: Minor improvements. To appear in Geometric Aspects of Functional
Analysis -- Israel Seminar (GAFA) 2017-2019", Lecture Notes in Mathematics
225
An (inverse) Pieri formula for Macdonald polynomials of type C
We give an explicit Pieri formula for Macdonald polynomials attached to the
root system C_n (with equal multiplicities). By inversion we obtain an explicit
expansion for two-row Macdonald polynomials of type C.Comment: 31 pages, LaTeX, to appear in Transformation Group
Islands of linkage in an ocean of pervasive recombination reveals two-speed evolution of human cytomegalovirus genomes
Human cytomegalovirus (HCMV) infects most of the population worldwide, persisting throughout the host's life in a latent state with periodic episodes of reactivation. While typically asymptomatic, HCMV can cause fatal disease among congenitally infected infants and immunocompromised patients. These clinical issues are compounded by the emergence of antiviral resistance and the absence of an effective vaccine, the development of which is likely complicated by the numerous immune evasins encoded by HCMV to counter the host's adaptive immune responses, a feature that facilitates frequent super-infections. Understanding the evolutionary dynamics of HCMV is essential for the development of effective new drugs and vaccines. By comparing viral genomes from uncultivated or low-passaged clinical samples of diverse origins, we observe evidence of frequent homologous recombination events, both recent and ancient, and no structure of HCMV genetic diversity at the whole-genome scale. Analysis of individual gene-scale loci reveals a striking dichotomy: while most of the genome is highly conserved, recombines essentially freely and has evolved under purifying selection, 21 genes display extreme diversity, structured into distinct genotypes that do not recombine with each other. Most of these hyper-variable genes encode glycoproteins involved in cell entry or escape of host immunity. Evidence that half of them have diverged through episodes of intense positive selection suggests that rapid evolution of hyper-variable loci is likely driven by interactions with host immunity. It appears that this process is enabled by recombination unlinking hyper-variable loci from strongly constrained neighboring sites. It is conceivable that viral mechanisms facilitating super-infection have evolved to promote recombination between diverged genotypes, allowing the virus to continuously diversify at key loci to escape immune detection, while maintaining a genome optimally adapted to its asymptomatic infectious lifecycle
A new multivariable 6-psi-6 summation formula
By multidimensional matrix inversion, combined with an A_r extension of
Jackson's 8-phi-7 summation formula by Milne, a new multivariable 8-phi-7
summation is derived. By a polynomial argument this 8-phi-7 summation is
transformed to another multivariable 8-phi-7 summation which, by taking a
suitable limit, is reduced to a new multivariable extension of the
nonterminating 6-phi-5 summation. The latter is then extended, by analytic
continuation, to a new multivariable extension of Bailey's very-well-poised
6-psi-6 summation formula.Comment: 16 page
Isometry theorem for the Segal-Bargmann transform on noncompact symmetric spaces of the complex type
We consider the Segal-Bargmann transform for a noncompact symmetric space of
the complex type. We establish isometry and surjectivity theorems for the
transform, in a form as parallel as possible to the results in the compact
case. The isometry theorem involves integration over a tube of radius R in the
complexification, followed by analytic continuation with respect to R. A
cancellation of singularities allows the relevant integral to have a
nonsingular extension to large R, even though the function being integrated has
singularities.Comment: Final version. To appear in Journal of Functional Analysis. Minor
revision
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