The formation of spiral arms and rings in barred galaxies

In this and in a previous paper (Romero-Gomez et al. 2006) we propose a theory to explain the formation of both spirals and rings in barred galaxies using a common dynamical framework. It is based on the orbital motion driven by the unstable equilibrium points of the rotating bar potential. Thus, spirals, rings and pseudo-rings are related to the invariant manifolds associated to the periodic orbits around these equilibrium points. We examine the parameter space of three barred galaxy models and discuss the formation of the different morphological structures according to the properties of the bar model. We also study the influence of the shape of the rotation curve in the outer parts, by making families of models with rising, flat, or falling rotation curves in the outer parts. The differences between spiral and ringed structures arise from differences in the dynamical parameters of the host galaxies. The results presented here will be discussed and compared with observations in a forthcoming paper.Comment: 16 pages, 13 figures, accepted in A&A. High resolution version available at http://www.oamp.fr/dynamique/pap/merce.htm

La “discapacidad” en debate: Puntos de tensión entre la vivencia comunitaria y la experiencia escolar

versión electrónicaInvestigación de corte etnográfico, realizada en Iztapalapa, Distrito Federal, México. Presenta algunos hallazgos preliminares sobre la relación entre familia, escuela y comunidad con respecto a las formas de concebir y atender la “discapacidad”. Esta investigación parte de la lógica de que la “discapacidad” es una construcción sociocultural, por lo cual en el texto el término aparecerá entrecomillado, dando cuenta de que es un constructo relativo y en interacción con el entorno. Las observaciones y entrevistas se realizaron en escenarios comunitarios: mercados, fiestas populares, domicilios particulares, Centros de Atención Múltiple y otros espacios colectivos. A partir del trabajo de campo se presentan algunos hallazgos organizados en una categoría de análisis denominada Discapacidad: diferentes lecturas desde la escuela y la comunidad. Tomando como referencia teórica la construcción sociocultural de la discapacidad se concluyó que la tensión que experimentan algunas familias de niños que asisten a escuelas de educación especial deriva de la persistencia del modelo clínico patologizante que se filtran de la escuela y otras instituciones médicas, pero que contrasta y encuentra resistencias con prácticas comunitarias que se muestran más receptivas de las diferencias.Beca de doctorado CONACY

Biodiversity study of Southern Biscayne Bay and Card Sound 1968-1973

A multi-disciplinary investigation was conducted in southern Biscayne Bay and Card Sound from 1968 to 1973. The purpose of the investigation was to conduct an integrated study of the ecology of southern Biscayne Bay with special emphasis on the effects of the heated effluent from the Turkey Point fossil fuel power plant, and to predict the impact of additional effluent from the planned conversion of the plant to nuclear fuel. The results of this investigation have been discussed in numerous publications. This report contains the unpublished biology data that resulted from the investigation. (PDF contains 44 pages

Alternative method for the metrological characterization of spur gears in the sub-millimeter range using optical equipment

The aim of this work is to develop a software that allows the inspection of spur gear manufactured in the sub-millimeter range. The measurements are made using a digital optical machine and using an analysis proprietary software implemented in Matlab®, which is able to handle images, captured using the digital optical machine. The software allows to evaluate the profile and pitch deviations as establish in the ISO/TR 10064-1:1992 standar

On the potential contribution of rooftop PV to a sustainable electricity mix: the case of Spain

This work evaluates the potential contribution of rooftop PV to the future electricity mix. Several sustainable scenarios are considered, each comprising different shares of centralized renewables, rooftop PV and storage. For each generation scenario, the storage capacity that balances the net hourly demand is determined, and the portfolio combination that minimizes the cost of supplying electricity is obtained. The analysis is applied to mainland Spain, using public information and detailed granular models, both in time (hourly resolution) and space (municipal level). For the Spanish case, when the flexibility of hydro and biomass generation is taken into account, the least-cost portfolio involves rather modest storage capacities, in the order of daily rather than seasonal values. This shows that a sustainable, almost emissions-free electricity system for Spain is possible, at a cost that can be even lower than current wholesale market prices.Comment: 7 tables & 11 figures in the main body (24 pages), and 13 pages for the supplementary material, wit

EL MALTRATO INFANTIL: CARACTERIZACIÓN Y MODELOS EXPLICATIVOS.

MONOGRAFÍ

Meeting the Need for K-8 Teachers for Classrooms with Culturally and Linguistically Diverse Students: The Promise and Challenge of Early Field Experiences

The writers present the findings of their study focused on teacher learning through early fieldwork experiences to address the problem of teachers working with a culturally and linguistically diverse student population. Data were analyzed from an archive collected from approximately 500 students enrolled in six undergraduate child development courses at three state university campuses located in urban areas of California. Findings suggest that early field experiences provide participants with opportunities for career goal clarification, and the context of field experience is significant and may lead to outcomes beyond the initial goal of the experience

Biometric presentation attack detection: beyond the visible spectrum

The increased need for unattended authentication in multiple scenarios has motivated a wide deployment of biometric systems in the last few years. This has in turn led to the disclosure of security concerns specifically related to biometric systems. Among them, presentation attacks (PAs, i.e., attempts to log into the system with a fake biometric characteristic or presentation attack instrument) pose a severe threat to the security of the system: any person could eventually fabricate or order a gummy finger or face mask to impersonate someone else. In this context, we present a novel fingerprint presentation attack detection (PAD) scheme based on i) a new capture device able to acquire images within the short wave infrared (SWIR) spectrum, and i i) an in-depth analysis of several state-of-theart techniques based on both handcrafted and deep learning features. The approach is evaluated on a database comprising over 4700 samples, stemming from 562 different subjects and 35 different presentation attack instrument (PAI) species. The results show the soundness of the proposed approach with a detection equal error rate (D-EER) as low as 1.35% even in a realistic scenario where five different PAI species are considered only for testing purposes (i.e., unknown attacks

The link between water access and subjective well-being: some methods and proposals.

The study of happiness or subjective well-being has traditionally been studied within the disciplines of psychology or sociology. Although economics has contemplated happiness in research terms, it has only recently been studied in any depth. In this paper we offer several proposals in order to investigate the relationship between water access and happiness, suggesting some situations that would merit further research. Moreover, we have included some methodological notes in order to achieve this objective. This relationship can be useful in two ways. Firstly, it can favour the contemplation of water access as a human right. Secondly, it can serve as a framework for the decision-making process carried out by Governments and NGOs in developing countries.