The Galactic Branches as a Possible Evidence for Transient Spiral Arms

With the use of a background Milky-Way-like potential model, we performed stellar orbital and magnetohydrodynamic (MHD) simulations. As a first experiment, we studied the gaseous response to a bisymmetric spiral arm potential: the widely employed cosine potential model and a self-gravitating tridimensional density distribution based model called PERLAS. Important differences are noticeable in these simulations, while the simplified cosine potential produces two spiral arms for all cases, the more realistic density based model produces a response of four spiral arms on the gaseous disk, except for weak arms -i.e. close to the linear regime- where a two-armed structure is formed. In order to compare the stellar and gas response to the spiral arms, we have also included a detailed periodic orbit study and explored different structural parameters within observational uncertainties. The four armed response has been explained as the result of ultra harmonic resonances, or as shocks with the massive bisymmetric spiral structure, among other. From the results of this work, and comparing the stellar and gaseous responses, we tracked down an alternative explanation to the formation of branches, based only on the orbital response to a self-gravitating spiral arms model. The presence of features such as branches, might be an indication of transiency of the arms.Comment: 17 pages, 9 figures. Accepted for publication in MNRA

EL «Ensayo encaminado a resolver un problema en la doctrina del azar»

El trabajo consta de una introducción biográfica en el que se recogen las pocas cosas que se conocen de la vida de Thomas Bayes. A continuación se tratan los antecedentes del problema de la probabilidad inversa y se comenta el Ensayo. Se recogen también tres aplicaciones añadidas al trabajo original de Thomas Bayes por Richard Price. Se incluyen las opiniones que el Ensayo ha suscitado a algunos eminentes estadísticos. [ABSTRACT] This work starts with a biographical introduction inc1uding a few things known of Thomas Bayes life. It is followed by the background to the inverse probability problem and the comments about the Essay. Three applications added to the original job of Thomas Bayes by Richard Price are included. Several opinions about the Essay given by some scientific figures are embodied at the end of the paper

Macro- and micro-modeling of crack propagation in encapsulation-based self-healing materials : application of XFEM and cohesive surface techniques

Encapsulation-based materials are produced introducing some small healing fluid-filled capsules in a matrix. These materials can self-heal when internal cracks intercept and break the capsules. If the healing agent is released, the crack can be sealed. However, this is not always the case. These capsules need to be designed with the adequate shape and material to be properly broken. This paper presents two application models based on the combination of eXtended Finite Element Method (XFEM) elements and Cohesive Surfaces technique (CS) to predict crack propagation. Two types of encapsulated systems are considered: a concrete beam in a three-point bending test, and a micro-scale model of a representative volume element of a polymer subjected to a uniaxial tensile test. Despite both systems rely on different capsule shapes and different constituent materials, the models predict a similar non-linear response of the overall material strength governed by the coupled effect of the interface strength and the capsule radii-to-thickness ratio. Furthermore, even if an inadequate material and geometry combination is used, it is found that the mere presence of capsules might achieve, under certain conditions, an interesting overall reinforcement effect. This effect is discussed in terms of clustering and volume fraction of capsules

A critical accounting project for Latin America? Objects of knowledge or ways of knowing

This article explores the basis of a critical accounting project in Latin America and suggests a critique inspired by the decolonial project to reinvigorate critical accounting. The paper draws on Santos’ (2009) sociology of absences to explore the epistemic assumptions present in interpretive and critical accounting studies focusing on Latin America to achieve these aims. The analysis reveals that the critical accounting studies analyzed often mobilize Anglo-Euro-Centric logics that limit the ability of Latin America to think itself and impede the dialogue on equal terms between contemporaries, as suggested by the decolonial project. The paper presents avenues for critical accounting research in Latin America, assessing the effects of the Anglo-European institutionalization of modes of doing research for Latin America and calling for authenticity, more attention to the existence of alternative ways of knowing in the global South and for the creation of protected spaces that care for those alternatives and grant an equal exchange of ideas.The Spanish Ministry of Science & Innovation provided financial support for this research (Grant RTI2018-099920-B-I00). A previous draft of this paper was presented at the Qualitative Research and Critical Accounting (QRCA) 2019 Conference, at an special issue webminar in September 2020 and at research seminars in Durham University Business School and ESSEC Business School. We are very grateful for the comments made by Yves Gendron, Giovanna Michelon, Daniel Martínez and Hector J. Sarmiento to previous drafts, two anonymous reviewers and the editors of this special issue. Of course, the views and remaining mistakes are obviously the authors’ exclusive responsibility. We are immensely indebted to Conny Beck for her encouragement to submit our manuscript to this special issue

USO DE DEXMEDETOMIDINA EN ANESTESIA GENERAL PARA DISMINUCION DE REQUERIMIENTO DE NARCOTICOS EN PACIENTES CON FARMACODEPENDENCIA

La dependencia a una sustancia ingerida de manera recurrente por un individuo presenta un reto en la administración de la anestesia; ya que al producirse la adaptación del organismo a la droga, con el transcurso del tiempo, la misma dosis tiende a disminuir el efecto. Diversos estudios demuestran que personas farmacodependientes durante un procedimiento anestésico consumen mayores cantidades de narcóticos; es por ello que el presente estudio, demuestra una disminución del uso de narcóticos tras la administración de dexmedetomidina durante la anestesia general balanceada en pacientes con farmacodependencia sometidos a procedimiento anestésico-quirúrgico electivo o de urgencia. Se realizó un estudio longitudinal, descriptivo, experimental y prospectivo. Se seleccionaron pacientes con farmacodependencia que cubrieran los siguientes criterios: 16 a 45 años de edad; estado físico ASA I, II y III; que requirieran procedimiento anestésico-quirúrgico de forma electiva o de urgencia con anestesia general balanceada, los cuales previa aceptación se dividieron en dos grupos, el primer grupo fue el principal en el cual se aplicó Dexmedetomidina a dosis de 0.5 mcg/Kg en infusión aforada en 50 ml de solución fisiológica al 0.9%, 30 minutos antes del procedimiento anestésico y el segundo grupo fue al que se le dio tratamiento convencional de anestésicos sin dexmedetomidina. Estos pacientes fueron monitorizados y evaluados durante el periodo preanestésico, transanestésico y postanestésico para la identificación de incidencias y/o complicaciones previo llenado de hoja de recolección de datos. Dicho estudio muestra una disminución marcada del requerimiento de narcótico durante una anestesia general balanceada tras la administración de dexmedetomidina, siendo estadisticamente no significativa, requiriendo la realización de estudios posteriores para obtener una muestra de población mayor que apoye lo demostrado en el presente trabajo

epsilon-Contaminated priors in contingency tables

An r x s table is used for different approaches to statistical inference. We develop a Bayesian procedure to test simple null hypotheses versus bilateral alternatives in contingency tables. We consider testing equality of proportions of independent multinomial distributions when the common proportions are known. A lower bound of the posterior probabilities of the null hypothesis is calculated with respect to a mixture of a point prior on the null and an epsilon-contaminated prior on the proportions under the alternative. The resulting Bayes tests are compared numerically to Pearson's chi(2) in a number of examples. For the examined examples the lower bound and the p-value can be made close. The obtained results are generalized when the common proportions vector under the null is unknown or has a known functional form