Arbitrary decomposition of a Mueller matrix

Mueller polarimetry involves a variety of instruments and technologies whose importance and scope of applications are rapidly increasing. The exploitation of these powerful resources depends strongly on the mathematical models that underlie the analysis and interpretation of the measured Mueller matrices and, very particularly, on the theorems for their serial and parallel decompositions. In this Letter, the most general formulation for the parallel decomposition of a Mueller matrix is presented, which overcomes certain critical limitations of the previous approaches, particularly the unnecessary exigency that the Mueller matrices of all parallel components have to be normalized in order to have equal transmittances for unpolarized light. In addition, the obtained results lead to a generalization of the polarimetric subtraction procedure and allow for a formulation of the arbitrary decomposition that integrates, in a natural way, the passivity criterion

El crédito comercial y la crisis crediticia: un análisis descriptivo en Europa; Reino Unido y España

El uso de crédito comercial como forma de financiar el corto plazo ha aumentando en los últimos años, las grandes empresas utilizan más días del que necesitan para realizar los pagos a las pequeñas empresas, lo que provoca fatales consecuencias financieras para los proveedores. Estos problemas financieros no son nuevos, pero con la restricción pronunciada del crédito los problemas se agudizan debido a que el uso masivo del crédito comercial repercute negativamente en los proveedores cuya insolvencia y riesgo de quiebra aumentan. En este trabajo se revisan de forma descriptiva el uso del crédito comercial en la crisis crediticia. Las principales contribuciones de la ponencia son dos. En primer lugar, mostrar las consecuencias financieras por la utilización del crédito comercial y, concretamente, en la crisis crediticia, y cómo el gobierno de Reino Unido desarrolla políticas públicas de pago para reducir el efecto negativo de los impagados. En segundo lugar, estudiar y comparar la situación de los países europeos en términos de pago a los proveedores y, en particular, el caso de Reino Unido, pero también el caso Español.The use of trade credit as a short-term financing is increasing in the last years; large firms use more days to pay small firms than they need, which causes financial fatal consequences to suppliers. These financial problems are not new, but with the credit crunch they are coming up because the massive use of the trade credit impacts negatively on suppliers whose insolvency and bankruptcy risks increase. In this paper we review in a descriptive way the use of trade credit in the credit crunch. The main contributions of the paper are two. Firstly, we show the financial consequences of the use of trade credit, and specifically in credit crisis, and how UK government develop public payment policies to reduce the negative effect of delete payments. Secondly, we study and compare the situation of European countries in terms of payment to suppliers, and in particular the case of UK, but also Spanish case

Algorithm for the numerical calculation of the serial components of the normal form of depolarizing Mueller matrices

The normal form of a depolarizing Mueller matrix constitutes an important tool for the phenomenological interpretation of experimental polarimetric data. Due to its structure as a serial combination of three Mueller matrices, namely a canonical depolarizing Mueller matrix sandwiched between two pure (nondepolarizing) Mueller matrices, it overcomes the necessity of making a priori choices on the order of the polarimetric components, as this occurs in other serial decompositions. Because Mueller polarimetry addresses more and more applications in a wide range of areas in science, engineering, medicine, etc., the normal form decomposition has an enormous potential for the analysis of experimentally determined Mueller matrices. However, its systematic use has been limited to some extent because of the lack of numerical procedure for the calculation of each polarimetric component, in particular in the case of Type II Mueller matrices. In this work, an efficient algorithm applicable to the decomposition of both Type II and Type I Mueller matrices is presented

Is the Voter Model a model for voters?

The voter model has been studied extensively as a paradigmatic opinion dynamics' model. However, its ability for modeling real opinion dynamics has not been addressed. We introduce a noisy voter model (accounting for social influence) with agents' recurrent mobility (as a proxy for social context), where the spatial and population diversity are taken as inputs to the model. We show that the dynamics can be described as a noisy diffusive process that contains the proper anysotropic coupling topology given by population and mobility heterogeneity. The model captures statistical features of the US presidential elections as the stationary vote-share fluctuations across counties, and the long-range spatial correlations that decay logarithmically with the distance. Furthermore, it recovers the behavior of these properties when a real-space renormalization is performed by coarse-graining the geographical scale from county level through congressional districts and up to states. Finally, we analyze the role of the mobility range and the randomness in decision making which are consistent with the empirical observations.Comment: 13 pages, 13 figure

p75 and Trk oncoproteins expression is developmentally regulated in the inner ear of human embryos

2 páginas, 1 figura, 1 tabla.-- et al.Peer Reviewe

Physical significance of the determinant of a Mueller matrix

The determinant of a Mueller matrix M plays an important role in both polarization algebra and the interpretation of polarimetric measurements. While certain physical quantities encoded in M admit a direct interpretation, the understanding of the physical and geometric significance of the determinant of M (detM) requires a specific analysis, performed in this work by using the normal form of M, as well as the indices of polarimetric purity (IPP) of the canonical depolarizer associated with M. We derive an expression for detM in terms of the diattenuation, polarizance and a parameter proportional to the volume of the intrinsic ellipsoid of M. We likewise establish a relation existing between the determinant of M and the rank of the covariance matrix H associated with M, and determine the lower and upper bounds of detM for the two types of Mueller matrices by taking advantage of their geometric representation in the IPP space