Antonio Javier Chamorro Fernández

Stress–energy–momentum tensors in higher order variational calculus

Abstract Given a variational problem defined by a natural Lagrangian density L ω on the k-jet extension Jk(Y/X) of a natural bundle p:Y→X over an n-dimensional manifold X, oriented by a volume element ω, a stress–energy–momentum tensor T(s) is constructed for each section s∈Γ(X,Y) from the multimomentum map μ Θ :Γ(X,Y)→ Hom R ( X (X),Ω n−1 (X)) associated to any Poincare–Cartan form Θ and to the natural lifting of vector fields X (X) to the bundle Y→X. The characterization made for T(s) gives an intrinsic expression of this tensor as well as a generalization of the classical Belinfante–Rosenfeld formula. This tensor satisfies the typical properties of a stress–energy–momentum tensor: Diff(X)-covariance, Hilbert formula, conservation law, etc. Furthermore, it plays the expected role in the theory of minimal gravitational interactions.

Stress–energy–momentum tensors for natural constrained variational problems

Abstract Under certain parameterization conditions for the “infinitesimal admissible variations”, we propose a theory for constrained variational problems on arbitrary bundles, which allows us to introduce in a very general way the concept of multi-momentum map associated to the infinitesimal symmetries of the problem. For natural problems with natural parameterization, a stress–energy–momentum tensor is constructed for each “admissible section” from the multi-momentum map associated to the natural lifting of vector fields on the base manifold. This tensor satisfies the typical properties of a stress–energy–momentum tensor (Diff( X )-covariance, Belinfante–Rosenfeld type formulas, etc.), and also satisfies corresponding conservation and Hilbert type formulas for natural problems depending on a metric. The theory is illustrated with several examples of geometrical and physical interest.

Proyecto Wernicke-SEMI: estudio multicéntrico y retrospectivo sobre la encefalopatía de Wernicke

espanolLa encefalopatia de Wernicke (EW) es una patologia neuropsiquiatrica aguda o subaguda debida al deficit de tiamina y que clasicamente se caracteriza por la presencia de confusion mental, oftalmoplejia y ataxia de la marcha. Existen numerosas areas de incertidumbre desde los puntos de vista epidemiologico, clinico, diagnostico y terapeutico, motivos por los que se ha disenado un estudio multicentrico dentro del grupo de trabajo de Alcohol y Alcoholismo de la Sociedad Espanola de Medicina Interna (SEMI) que trate de dilucidar estos aspectos. EnglishWernicke Encephalopathy is an acute or subacute neuropsychiatric disease due to thiamine deficiency, which has been classically defined by the triad of confusional state, ophthalmoplegia and gait disturbance. Due to the fact that there are many areas of uncertainty regarding epidemiologic, diagnostic and therapeutic aspects of this disease, the Alcohol and Alcoholism Working Group of the Spanish Society of Internal Medicine (SEMI) has promoted a multicenter study to analyze these points.

Gauge-invariant covariant Hamiltonians

Given an Ehresmann connection γ on a fibered manifold p:E→M, a covariant Hamiltonian density Hγ is then associated to each Lagrangian density L on J1E. Assume E is the bundle of connections of a principal bundle and that L is gauge invariant. Our goal in this paper is to determine conditions on γ under which Hγ is also gauge invariant. The general conclusion is that there is no gauge-invariant Ehresmann connection but there is plenty of such connections providing gauge-invariant covariant Hamiltonians. The relevant cases of U(1) bundles and SU(2) bundles are discussed in detail.

Adenopatía supraclavicular como forma de presentación de un carcinoma de cérvix asociado al complejo esclerosis tuberosa con linfangioleiomiomatosis

espanolLa linfangioleiomiomatosis es una proliferacion del tejido muscular broncovascular que recientemente se ha definido como una expresion incompleta de la entidad �complejo esclerosis tuberosa�, una facomatosis a la que se asocian diversas neoplasias. Presentamos un caso de carcinoma de cervix con metastasis supraclaviculares y cervicales, asociado a linfangioleiomiomatosis en el contexto de un �complejo esclerosis tuberosa�. EnglishLymphangioleiomyomatosis is a proliferation of the bronchovascular smooth muscle, which has been defined recently as an incomplete expression of the �Tuberous Sclerosis Complex� entity, a phacomatosis related to several neoplasms. We introduce a case of adenocarcinoma of the cervix with supraclavicular and neck metastases, associated with symphangioleiomyomatosis in the context of �Tuberous Sclerosis Complex