Leaky modes of waveguides as a classical optics analogy of quantum resonances

A classical optics waveguide structure is proposed to simulate resonances of short range one-dimensional potentials in quantum mechanics. The analogy is based on the well known resemblance between the guided and radiation modes of a waveguide with the bound and scattering states of a quantum well. As resonances are scattering states that spend some time in the zone of influence of the scatterer, we associate them with the leaky modes of a waveguide, the latter characterized by suffering attenuation in the direction of propagation but increasing exponentially in the transverse directions. The resemblance is complete since resonances (leaky modes) can be interpreted as bound states (guided modes) with definite lifetime (longitudinal shift). As an immediate application we calculate the leaky modes (resonances) associated with a dielectric homogeneous slab (square well potential) and show that these modes are attenuated as they propagate.Comment: The title has been modified to describe better the contents of the article. Some paragraphs have been added to clarify the result

Superpositions of bright and dark solitons supporting the creation of balanced gain and loss optical potentials

Bright and dark solitons of the cubic nonlinear Schrodinger equation are used to construct complex-valued potentials with all-real spectrum. The real part of these potentials is equal to the intensity of a bright soliton while their imaginary part is defined by the product of such soliton with its concomitant, a dark soliton. Considering light propagation in Kerr media, the real part of the potential refers to the self-focusing of the signal and the imaginary one provides the system with balanced gain-and-loss rates.Comment: 6 figures, 17 pages, LaTeX file. The manuscript has been re-organized (abstract, introduction and conclusions rewritten), and it now includes an appendix with detailed calculations of some relevant results reported in the paper. New references were adde

Dynamical Equations, Invariants and Spectrum Generating Algebras of Mechanical Systems with Position-Dependent Mass

We analyze the dynamical equations obeyed by a classical system with position-dependent mass. It is shown that there is a non-conservative force quadratic in the velocity associated to the variable mass. We construct the Lagrangian and the Hamiltonian for this system and find the modifications required in the Euler-Lagrange and Hamilton's equations to reproduce the appropriate Newton's dynamical law. Since the Hamiltonian is not time invariant, we get a constant of motion suited to write the dynamical equations in the form of the Hamilton's ones. The time-dependent first integrals of motion are then obtained from the factorization of such a constant. A canonical transformation is found to map the variable mass equations to those of a constant mass. As particular cases, we recover some recent results for which the dependence of the mass on the position was already unnoticed, and find new solvable potentials of the P\"oschl-Teller form which seem to be new. The latter are associated to either the su(1,1) or the su(2) Lie algebras depending on the sign of the Hamiltonian

Completeness and Nonclassicality of Coherent States for Generalized Oscillator Algebras

The purposes of this work are (1) to show that the appropriate generalizations of the oscillator algebra permit the construction of a wide set of nonlinear coherent states in unified form; and (2) to clarify the likely contradiction between the nonclassical properties of such nonlinear coherent states and the possibility of finding a classical analog for them since they are P-represented by a delta function. In (1) we prove that a class of nonlinear coherent states can be constructed to satisfy a closure relation that is expressed uniquely in terms of the Meijer G-function. This property automatically defines the delta distribution as the P-representation of such states. Then, in principle, there must be a classical analog for them. Among other examples, we construct a family of nonlinear coherent states for a representation of the su(1,1) Lie algebra that is realized as a deformation of the oscillator algebra. In (2), we use a beam splitter to show that the nonlinear coherent states exhibit properties like anti-bunching that prohibit a classical description for them. We also show that these states lack second order coherence. That is, although the P-representation of the nonlinear coherent states is a delta function, they are not full coherent. Therefore, the systems associated with the generalized oscillator algebras cannot be considered `classical' in the context of the quantum theory of optical coherence.Comment: 26 pages, 10 figures, minor changes, misprints correcte

LA INTERVENCION SOCIOEDUCATIVA, UNA MODALIDAD DE EDUCACION AMBIENTAL CASO: ANALISIS DE LA REVISTA IMPULSO AMBIENTAL Y MATERIALES DIDACTICOS DE LA SEMARNAT

La comunicación en todas sus facetas y formas de expresión implica necesariamente el intercambio de información a través de códigos previamente establecidos. Por medio de la comunicación se transmiten mensajes que buscan influir en el cambio de actitudes de los participantes en ésta. También es susceptible de análisis a partir de las modificaciones y agregados que va teniendo como parte del desarrollo de la disciplina. La comunicación a partir de los elementos teóricos y metodológicos que posee, permite analizar el mundo y explicarlo de mejor forma. Un caso concreto es la comunicación ambiental, la tesis muestra como la comunicación ambiental se integra a intervenciones socioeducativas. Y como a partir de las estrategias de la intervención se comprende la comunicación ambiental que genera cambios de actitud en la relación ser humano-naturaleza. En esta investigación se retoma la experiencia obtenida en el desempeño profesional en la Secretaría de Medio Ambiente y Recursos Naturales (SEMARNAT) dependiente del Gobierno Federal, una de cuyas funciones es la capacitación y divulgación del conocimiento ecológico y educación ambiental. Divulgación que se realiza en principio con el material didáctico y contenidos de la revista Impulso Ambiental, realizados por el Centro de Educación y Capacitación para el Desarrollo sustentable (CECADESU)

El rol de la eficacia colectiva en el desempeño y bienestar de los trabajadores. Un estudio de caso en el sector de hostelería

Catorzenes Jornades de Foment de la Investigació de la FCHS (Any 2008-2009)The objective the work of the same one is to analyze the relation between collective effectiveness and the psycho-social well-being of the employees and its performance. Following the Heuristic Model of Healthful Organization and from the Social Theory Cognitiva de Bandura (1997, 1999, 2001), test the hypothesis of the positive effect of the collective effectiveness will be put on engagement of the employees and their performance (intra and extra-roll) in a company of services of the tourist sector of the province of Castellón. The sample is formed by a total of 25 workers (42 %hombre and 58% women) grouped in areas on watch (42%) and restoration (26%). Los results they show that it exists a positive relation between the collective effectiveness and the performance (intra and extra-roll) and a positive relation between collective effectiveness and engagement.El objetivo de este trabajo es analizar la relación entre eficacia colectiva y bienestar psicosocial de los empleados y su desempeño. Siguiendo el Modelo Heurístico de Organización Saludable y desde la Teoría Social Cognitiva de Bandura (1997, 1999, 2001), se pondrá a prueba la hipótesis del efecto positivo de la eficacia colectiva sobre el engagement de los empleados y su desempeño (intra y extrarol) en una empresa del sector de hostelería de la provincia de Castellón. La muestra está formada por un total de 25 trabajadores (42%hombre y 58% mujeres) agrupados en áreas de servicio (42%) y restauración (26%).Los resultados muestran que existe una relación positiva entre la eficacia colectiva y el desempeño (intra y extra-rol) y una relación positiva entre eficacia colectiva y engagement

¿Cómo experimentan placer los animales? Una aproximación desde Aristóteles

En este artículo analizo el papel del placer en el comportamiento animal según aristóteles, poniendo en relación la doctrina del placer de la etica a nicómaco con textos del de anima y el de motu animalium. Los animales son vivientes que interiorizan susIn this article I study the role of pleasure in animals' behaviour according to aristotle, trying to relate the doctrine of pleasure of the nicomachean ethics with some texts of the de anima and motu animalium. Animals are living beings which internaliz