Differential description and irreversibility of depolarizing light-matter interactions

The widely-used Jones and Mueller differential polarization calculi allow non-depolarizing deterministic polarization interactions, known to be elements of the $SO^+(1,3)$ Lorentz group, to be described in an efficient way. In this Letter, a stochastic differential Jones formalism is shown to provide a clear physical insight on light depolarization, which arises from the interaction of polarized light with a random medium showing fluctuating anisotropic properties. Based on this formalism, several "intrinsic" depolarization metrics naturally arise to efficiently characterize light depolarization in a medium, and an irreversibility property of depolarizing transformations is finally established

Polarimetric study of birefringent turbid media with three-dimensional optic axis orientation

Recent approaches to the analysis of biological samples with three-dimensional linear birefringence orientation require numerical methods to estimate the best fit parameters from experimental measures. We present a novel analytical method for characterizing the intrinsic retardance and the three-dimensional optic axis orientation of uniform and uniaxial turbid media. It is based on a model that exploits the recently proposed differential generalized Jones calculus, remarkably suppressing the need for numerical procedures. The method is applied to the analysis of samples modeled with polarized sensitive Monte Carlo. The results corroborate its capacity to successfully characterize 3D linear birefringence in a straightforward way

Depolarizing differential Mueller matrices

The evolution of a polarized beam can be described by the differential formulation of Mueller calculus. The nondepolarizing differential Mueller matrices are well known. However, they only account for 7 out of the 16 independent parameters that are necessary to model a general anisotropic depolarizing medium. In this work we present the nine differential Mueller matrices for general depolarizing media, highlighting the physical implications of each of them. Group theory is applied to establish the relationship between the differential matrix and the set of transformation generators in the Minkowski space, of which Lorentz generators constitute a particular subgroup

A case of atypical disseminated herpes simplex virus 1 with hepatitis in a liver transplant recipient: the need for dermatologic evaluation

Disseminated herpes simplex virus (HSV) is mainly seen in immunocompromised individuals. Atypical lesions can be present in both primary infection and reactivation disease. Compared with the general population, inmunocompromised hosts are at greater risk of increased persistency and severity of clinical manifestations, including severe systemic involvement such as esophagitis, meningitis, and hepatitis. Herein, we report the case of a liver transplant recipient with atypical disseminated herpes simplex virus-1 complicated by HSV-related hepatitis. Dermatological consultation and histological assessment were crucial for a correct diagnosis and treatment

Influence of corona charging in cellular polyethlene film

[En] Cellular polymers have recently attracted attention for their property of exhibiting a piezoelectric constant when they are electrically charged. The electrostatic charge generated in the voids by the internal discharges creates and internal macrodipole which is responsible for the piezoelectric effect. Charging by corona discharge is the most used method for cellular polymers. Many works has been published on polypropylene and polyethylene films mainly focused on the required expansion process or on the results obtained for raw cellular materials electrically activated. Our work is based on commercial polyethylene cellular films which have been physically characterized and electrically activated. The effect of thermal treatment, physical uniaxial or biaxial stretching and corona charging was investigated. The new method of corona charging improved the piezoelectric constant under other activation conditions.This work has been developed under the project Intelligent Materials with Mechanical and Electrical Properties interaction (E-MAT)" which has been submitted for funding with reference number IMDEEA/2011/13 to the call of Technological Centers of IMPIVA Network 2011, Strategic development program (action 1, R+D projects) financed by the Generalitat Valenciana through the Instituto de la Mediana y Pequena Empresa Valenciana (IMPIVA) and the European Regional Development Fund (ERDF).Ortega Braña, GE.; Llovera Segovia, P.; Magraner Bella, F.; Quijano Lopez, A. (2011). Influence of corona charging in cellular polyethlene film. Journal of Physics: Conference Series. 301:1-4. doi:10.1088/1742-6596/301/1/012054S14301Fukada, E. (2000). History and recent progress in piezoelectric polymers. IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 47(6), 1277-1290. doi:10.1109/58.883516Sessler, G. M., & Hillenbrand, J. (1999). Electromechanical response of cellular electret films. Applied Physics Letters, 75(21), 3405-3407. doi:10.1063/1.125308Hillenbrand, J., & Sessler, G. M. (2000). Piezoelectricity in cellular electret films. IEEE Transactions on Dielectrics and Electrical Insulation, 7(4), 537-542. doi:10.1109/94.868074Paajanen, M., Välimäki, H., & Lekkala, J. (2000). Modelling the electromechanical film (EMFi). Journal of Electrostatics, 48(3-4), 193-204. doi:10.1016/s0304-3886(99)00065-0Gerhard-Multhaupt, R. (2002). Less can be more. Holes in polymers lead to a new paradigm of piezoelectric materials for electret transducers. IEEE Transactions on Dielectrics and Electrical Insulation, 9(5), 850-859. doi:10.1109/tdei.2002.1038668Wegener, M., & Bauer, S. (2005). Microstorms in Cellular Polymers: A Route to Soft Piezoelectric Transducer Materials with Engineered Macroscopic Dipoles. ChemPhysChem, 6(6), 1014-1025. doi:10.1002/cphc.200400517Hillenbrand, J., Behrendt, N., Mohmeyer, N., Altsadt, V., Schmidt, H.-W., & Sessler, G. M. (s. f.). Charge retention in biaxially-oriented polypropylene films containing various additives. 2005 12th International Symposium on Electrets. doi:10.1109/ise.2005.1612375Xiaoqing Zhang, Sessler, G. M., & Hillenbrand, J. (s. f.). Optimization of Piezoelectric Properties of Cellular Polypropylene Films by Repeated Expansion. 2005 12th International Symposium on Electrets. doi:10.1109/ise.2005.161231

Generalized Jones matrix method for homogeneous biaxial samples

International audienceThe generalized Jones matrix (GJM) is a recently introduced tool to describe linear transformations of three-dimensional light fields. Based on this framework, a specific method for obtaining the GJM of uniaxial anisotropic media was recently presented. However, the GJM of biaxial media had not been tackled so far, as the previous method made use of a simplified rotation matrix that lacks a degree of freedom in the three-dimensional rotation, thus being not suitable for calculating the GJM of biaxial media. In this work we propose a general method to derive the GJM of arbitrarily-oriented homogeneous biaxial media. It is based on the differential generalized Jones matrix (dGJM), which is the three-dimensional counterpart of the conventional differential Jones matrix. We show that the dGJM provides a simple and elegant way to describe uniaxial and biaxial media, with the capacity to model multiple simultaneous optical effects. The practical usefulness of this method is illustrated by the GJM modeling of the polarimetric properties of a negative uniaxial KDP crystal and a biaxial KTP crystal for any three-dimensional sample orientation. The results show that this method constitutes an advantageous and straightforward way to model biaxial media, which show a growing relevance for many interesting applications

Generalized Jones matrices for anisotropic media

The interaction of arbitrary three-dimensional light beams with optical elements is described by the generalized Jones calculus, which has been formally proposed recently [Azzam, J. Opt. Soc. Am. A 28, 2279 (2011)]. In this work we obtain the parametric expression of the 3×3 differential generalized Jones matrix (dGJM) for arbitrary optical media assuming transverse light waves. The dGJM is intimately connected to the Gell-Mann matrices, and we show that it provides a versatile method for obtaining the macroscopic GJM of media with either sequential or simultaneous anisotropic effects. Explicit parametric expressions of the GJM for some relevant optical elements are provided

Mueller matrix differential decomposition for direction reversal: application to samples measured in reflection and backscattering

Mueller matrix differential decomposition is a novel method for analyzing the polarimetric properties of optical samples. It is performed through an eigenanalysis of the Mueller matrix and the subsequent decomposition of the corresponding differential Mueller matrix into the complete set of 16 differential matrices which characterize depolarizing anisotropic media. The method has been proposed so far only for measurements in transmission configuration. In this work the method is extended to the backward direction. The modifications of the differential matrices according to the reference system are discussed. The method is successfully applied to Mueller matrices measured in reflection and backscattering

Voz y creencias de los estudiantes de primer curso del Grado de Educación Primaria sobre sus motivaciones para elegir profesión docente

La mejora de los procesos de enseñanza-aprendizaje está determinada por diferentes factores, pero consideramos que uno fundamental es el compromiso ético, consecuentemente, el desarrollo de la identidad profesional docente, y como determinante de los dos el motivo que le ha llevado a un estudiante del título de maestro a elegir esa carrera, aspecto que pretendemos conocer en el presente trabajo. El estudio tiene como informantes 38 autobiografías de estudiantes de primer curso del título de grado de Educación Primaria de la Universidad de Jaén, utilizando como metodología el análisis de relatos autobiográficos a través de la Teoría de la Acción Fundamentada. Las narrativas fueron seleccionadas atendiendo a la variedad, riqueza y grado de profundidad alcanzado en los aspectos que atienden a la temática formulada en el problema de investigación. Los estudiantes afirman que han optado por cursar el grado especificado, atendiendo a cuatro tipos de razones; bien por contacto con los niños a través de contacto con la educación o mediante experiencias de voluntariado, lo que les ha llevado a despertar su vocación docente; bien a través de la influencia de amigos, que les han aconsejado realizar los estudios de maestro porque es un trabajo seguro y bien remunerado. Estos estudiantes suelen pertenecer a la clase media-baja; otro tipo de estudiantes han accedido a esta carrera porque la nota media que tenían no les permitía optar a otra titulación; un cuarto grupo ha accedido a los estudios de magisterio por “la experiencia trasmitida de padres y familiares que trabajan en la educación” o por “la incidencia de sus profesores”, que les han ayudado a desarrollar su identidad profesional con el transcurso del tiempo. Por las aportaciones de los estudiantes, se puede considerar que el grupo primero, voluntariado y contacto con la educación, así como aquellos que han querido ser maestro por la experiencia vivida junto a sus profesores representa las señas de identidad más genuinas de la identidad profesional docente

Influencia de los solventes en la identificación de los contaminantes prioritarios del aire de Cúcuta.

Estudios epidemiológicos han puesto de manifiesto que el mayor factor de contaminación de la atmósfera urbana son las partículas en suspensión, conocidas como material particulado (PM), que incluye las partículas suspendidas totales (PST) y partículas de la fracción respirable entre las cuales tenemos al PM 10  (partículas con diámetro aerodinámico inferior a10 µm) conocidas como partículas finas y el PM2.5  conocido como material particulado ultrafino. La contaminación atmosférica producida por el material particulado (PM) es un problema mundial, el cuál es generado por las actividades industriales y tubos de escape de vehículos de motor.Estudios de fraccionamiento del material particulado orgánico (PM2.5 ) del aire, han identificado hidrocarburos policíclicos aromáticos (HAP) mutagénicos y carcinogénicos, que pueden causar daño oxidativo del ADN y pueden conducir a efectos cardiovasculares y reproductivos.Esta investigación tiene como objetivo mostrar la importancia de utilizar diferentes solventes en la extracción de la materia organica del PM2.5 (HAP) del aire de nuestras ciudades. Se muestran los HAP extraídos con elsistema DCM-Etanol-Tolueno y se comparan con los HAP extraídos con los solventes tradicionales Acetona y Diclorometano. La identificación de los HAP considerados como contaminantes prioritarios (CP) y reconocidos por su afectación a la salud de la población se realizó, mediante cromatografíade gases con detector FID. Los HAP (CP) encontrados en la ciudad de Cúcuta son:  Benzo[a]antraceno,Criseno,Benzo[k]fluoranteno ,Benzo[b] fluoranteno ,Benzo[a] Pireno, Indeno[1,2,3-cd] pireno y Dibenzo[a,h] antraceno