Massive Gravity in de Sitter Space via Gravitational Higgs Mechanism

In this paper we discuss massive gravity in de Sitter space via gravitational Higgs mechanism, which provides a nonlinear definition thereof. The Higgs scalars are described by a nonlinear sigma model, which includes higher derivative terms required to obtain the Fierz-Pauli mass term. Using the aforesaid non-perturbative definition, we address appearance of an enhanced local symmetry and a null norm state in the linearized massive gravity in de Sitter space at the special value of the graviton mass to the Hubble parameter ratio. By studying full non-perturbative equations of motion, we argue that there is no enhanced symmetry in the full nonlinear theory. We then argue that in the full nonlinear theory no null norm state is expected to arise at the aforesaid special value. This suggests that no ghost might be present for lower graviton mass values and the full nonlinear theory might be unitary for all values of the graviton mass and the Hubble parameter with no van Dam-Veltman-Zakharov discontinuity. We argue that this is indeed the case by studying full nonlinear Hamiltonian for the relevant conformal and helicity-0 longitudinal modes. In particular, we argue that no negative norm state is present in the full nonlinear theory.Comment: 22 pages, comments and references added. Phys.Rev.D versio

Jacobi Structures in R3\mathbb{R}^3

The most general Jacobi brackets in $\mathbb{R}^3$ are constructed after solving the equations imposed by the Jacobi identity. Two classes of Jacobi brackets were identified, according to the rank of the Jacobi structures. The associated Hamiltonian vector fields are also constructed

Quality management in socioeducational action

Nowadays. the quality of the services offered to citizens is of the almost importance. All public services ,ust be efficacious and excellent. The organisations and professionals who participate in socio educotiollal-action are greatly concerned with quality. Stimulating intemal qualiry management of services will boost process building and will make it possible to bring in tire necessary improvements in order to cater to social demands.En la actualidad es imprescindible plantearse la calidad de los servicios que se ofrecen a la ciudadanía. A cualquier servicio público hay que exigirle eficacia y excelencia. Organismos y profesionales que intervienen en la acción socioeducativa, tienen una gran preocupación por la calidad. Estimular la gestión de la calidad interna de los servicios potenciará el establecimiento de procesos que permitirán introducir las mejoras necesarias para dar respuestas a les demandas sociales.

Wavefront curvature sensing for the human eye

In this paper we present a curvature wavefront sensor for the eye. The layout proposed is novel, whilst the algorithm used has been adapted from previously published work [Roddier, F.; Roddier, C. Appl. Opt. 1991, 30, 1325–1327]. The design of the set-up incorporates two field lenses that, together with a beam separator, define the distance Δz between the two sampled planes. We present a feasibility study to use this particular combination of optical configuration and retrieval algorithm in the eye. We present calibration curves and results from three real eyes