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

Cannabinoid Receptors as Regulators of Neutrophil Activity in Inflammatory Diseases

Cannabinoids are compounds present in Cannabis sativa (phytocannabinoids), endogenously produced (endocannabinoids) or synthesized, that bind to G protein-coupled receptors named cannabinoid receptors B1 and B2. They were first described as psychotropic compounds; however, cannabinoids are also potent immunoregulatory agents. Cannabinoids can modulate neutrophil activity in sterile and infectious inflammatory diseases. Concerning sterile inflammatory diseases as arthritis, ischemic diseases, and colitis, the use of CB2 agonist impairs the intracellular signaling pathways involved in the production of inflammatory mediators and expression of adhesion molecules. As a consequence, neutrophils did not release metalloproteinases either to adhere to endothelial cells, resulting in reduced tissue damage. A similar anti-inflammatory CB2 agonist mechanism of action in sepsis and mycobacterial infection models is observed. However, it is not clear if inflammation resolution promoted by cannabinoid treatment during infection is also related to microbial viability. Despite the growing literature showing the effects of cannabinoids on neutrophils, there are still some gaps that should be filled before proposing cannabinoid-based drugs to treat neutrophil-dependent diseases

Social Work Towards a Quality of Life and Well Being Subjective

The quality of life understood as satisfaction related to resources, values, norms, expectations, perceptions and capabilities is a central issue in the public health agenda for sustainable local development (García, 2013). Some studies on quality of life provide significant gender differences regarding transportation, employment and recreation (Baldi & Garcia, 2010). Furthermore, when pondering as a perceptual system resources around the individual and in reference to the parent group, it is considered a style of personal well - being that is geared to social integration (Barranco, Delgado, Meli, & Quintana, 2010). But quality of life is correlated with anxiety and depression in medical situations of uncertainty and deteriorating health (Machado, Anarte, & Ruiz, 2010). That is, the quality of life is the result of the perception of scarcity of resources rather than the hopes generated from personal abilities. Opportunities seem to boil down to a minimum and thus the responsibility of self increases and an improvement in expectations is observed through the links between the members of a social, family or school group. Grimaldo (2010) found eight alluding to the quality of life dimensions. This is the economic well - being, interpersonal relationship, family situation, neighborhood context, social capital and health. Therefore, the quality of life is a web of expectations that are based on a figurative nucleus to influence the decisions of resource allocation (Carreon & Garcia, 2013).This work was proposed to establish a correlative model to discuss the importance of other variables in the investigation of the quality of life. Once the relationships between the factors derived from the literature review were specified, it conducted a cross sectional study with a non - probabilistic sample of 245 students. When the validity and reliability of the instrument measured was obtained: life satisfaction, expected capabilities, expectations of opportunity, trust relationships, perception of justice, assessment of the environment, standards of context and perceived resources, a structural model was tested [X 2 = 12,35 (12 gl); p = 0.000; GFI = 0.975; RMR = 0.000] in which the perceived availability of resources indirectly correlated to life satisfaction through standards context (γ = 0.52). The results were compared with findings reported in the state of knowledge