Dynamical constants for electromagnetic fields with elliptic-cylindrical symmetry

Taking into account the characteristics of a free scalar field in elliptic coordinates, a new dynamical variable is found for the free electromagnetic field. The conservation law associated to this variable cannot be obtained by direct application of standard Noether theorem since the symmetry generator is of second order. Consequences on the expected mechanical behavior of an atomic system interacting with electromagnetic waves exhibiting such a symmetry are also discussed.Comment: 17 pages, 5 figures, revised version, animated graphs provided at http://www.fisica.unam.mx/research/movie

Frank-Condon principle and adjustment of optical waveguides with nonhomogeneous refractive indices

The adjustment of two different selfocs is considered using both exact formulas for the mode-connection coefficients expressed in terms of Hermite polynomials of several variables and a qualitative approach based on the Frank-Condon principle. Several examples of the refractive-index dependence are studied and illustrative plots for these examples are presented. The connection with the tomographic approach to quantum states of a two-dimensional oscillator and the Frank-Condon factors is established.Comment: 8 pages, 4 figures, published version (layout of figures changed, typos corrected, references added

Consenso Mexicano de Hepatitis Alcohólica

La hepatitis alcohólica es una condición frecuente en la población mexicana, se caracteriza por insuficiencia hepática aguda sobre crónica, importante reacción inflamatoria sistémica y fallo multiorgánico, que en la variante grave de la enfermedad implica una elevada mortalidad. Por lo anterior, la Asociación Mexicana de Gastroenterología y la Asociación Mexicana de Hepatología conjuntaron un equipo multidisciplinario de profesionales de la salud para elaborar el primer consenso mexicano de hepatitis alcohólica. El consenso fue elaborado con la metodología Delphi, emitiendo 37 recomendaciones. La enfermedad hepática relacionada con el consumo de alcohol comprende un amplio espectro, que incluye esteatosis, esteatohepatitis, fibrosis en diferentes grados, cirrosis y sus complicaciones. La hepatitis alcohólica grave se define por una función modificada de Maddrey ≥ 32 o por un puntaje de MELD (Model for End- Stage Liver Disease) igual o mayor a 21. Actualmente no existe un biomarcador específico para el diagnóstico. La presencia de leucocitosis con neutrofilia, hiperbilirrubinemia (> 3 mg/dL),AST > 50 U/L ( 1.5-2 pueden orientar al diagnóstico. La piedraangular del tratamiento es la abstiencia junto con el soporte nutricional. Los esteroides estanindicados en la forma grave, en donde han resultado efectivos para reducir la mortalidad a28 días. El trasplante hepático es en la actualidad la única opción con que se cuenta parasalvar la vida de pacientes que no responden a los esteroides. Ciertos fármacos, como la N-acetilcisteína, el factor estimulante de colonias de granulocitos y la metadoxina, pueden seruna terapia adyuvante que puede mejorar la supervivencia de los pacientes

The Mexican consensus on alcoholic hepatitis

Alcoholic hepatitis is a frequent condition in the Mexican population. It is characterized by acute-on-chronic liver failure, important systemic inflammatory response, and multiple organ failure. The severe variant of the disease implies elevated mortality. Therefore, the Asociación Mexicana de Gastroenterología and the Asociación Mexicana de Hepatología brought together a multidisciplinary team of health professionals to formulate the first Mexican consensus on alcoholic hepatitis, carried out utilizing the Delphi method and resultingin 37 recommendations. Alcohol-related liver disease covers a broad spectrum of patholo-gies that includes steatosis, steatohepatitis, different grades of fibrosis, and cirrhosis and itscomplications. Severe alcoholic hepatitis is defined by a modified Maddrey’s discriminant func-tion score ≥ 32 or by a Model for End-Stage Liver Disease (MELD) score equal to or above 21.There is currently no specific biomarker for its diagnosis. Leukocytosis with neutrophilia, hyper-bilirubinemia (>3 mg/dl), AST > 50 U/l ( 1.5-2 can guide thediagnosis. Abstinence from alcohol, together with nutritional support, is the cornerstone oftreatment. Steroids are indicated for severe disease and have been effective in reducing the28-day mortality rate. At present, liver transplantation is the only life-saving option for patientsthat are nonresponders to steroids. Certain drugs, such as N-acetylcysteine, granulocyte-colonystimulating factor, and metadoxine, can be adjuvant therapies with a positive impact on patientsurvival

Nondiffracting beams: travelling, standing, rotating and spiral waves

A reformulation of nondiffracting beams, based on more general (travelling wave) solutions of the nonparaxial wave equation, is presented. Zero order nondiffracting beams are found to be radial standing waves arising from counterpropagating zero order Hankel waves of the first and second kind, while higher order nondiffracting beams are formed from counter-rotating spiral waves which are described by Hankel functions of the corresponding order. The resulting physical picture is more general than the well-known integral representation of Bessel functions and we expect it to have implications for studies of the applications of nondiffracting beams. Generic descriptions of the transverse profiles of the electric field, applicable to experimental configurations for realising nondiffracting beams, follow directly from this formulation. Finally, the existence of classes of periodically nondiffracting beams, possessing finite angular momentum and having the characteristics of rotating and spiral waves, is predicted

3-D Optical forces and transfer of orbital angular momentum from multi-ringed light beams to spherical microparticles

Experimental evidence of transfer of orbital angular momentum of multiringed beams to dielectric particles has been reported recently [e.g., J. Opt. B 4, S82 (2002); Phys. Rev. Lett. 91, 093602 (2003)]. Here we present a detailed theoretical examination of the forces involved in trapping and transferring orbital angular momentum to microparticles due to a multiringed light beam, particularly a Bessel beam. Our investigation gathers, in a more general way, the trapping forces for high-index and low-index dielectric transparent particles, as well as for reflective metallic particles, as a function of particle size and position relative to the dimensions of the rings of the beam. We find that particles can be trapped in different regions of the beam intensity profile according to their size and that an azimuthal force component opposite to the beam helicity may appear under certain circumstances, depending on the relative size and radial equilibrium position with respect to the beam for high-index spheres. (C) 2004 Optical Society of America.</p