Optically Induced Reorientation in Nematic Cylindrical Structures

Cyclindrical structures of nematics give rise to several opto-optical effects related to molecular reorientation. One of these effects is the formation of diffraction ring patterns similar to the ones observed in planar cells, but differing in shape. Another effect has been observed, namely a quasi-chaotic motion of rings with a very large angular spread; this motion can be obtained using a cw laser and high power densities. The phenomenon could be attributed to thermal motion, however, there are some features that cannot be explained by a purely thermal effect, e.g., a wavelength dependence of the threshold and the frequencies of the ring motion

The emergence of altruism as a social norm

Expectations, exerting influence through social norms, are a very strong candidate to explain how complex societies function. In the Dictator game (DG), people expect generous behavior from others even when they cannot enforce any sharing of the pie. Here we assume that people donate following their expectations, and that they update their expectation after playing a DG by reinforcement learning to construct a model that explains the main experimental results in the DG. Full agreement with the experimental results is reached when some degree of mismatch between expectations and donations is added into the model. These results are robust against the presence of envious agents, but affected if we introduce selfish agents that do not update their expectations. Our results point to social norms being on the basis of the generous behavior observed in the DG and also to the wide applicability of reinforcement learning to explain many strategic interactions

Multiple primary and secondary sources for chemically similar obsidians from the area of portada covunco, west-central Neuquén, Argentina

In west-central Neuquén Province, Argentina, in the area around Estancia Llamuco, west of Zapala, south of Las Lajas and north-east of Lago Aluminé, there are multiple primary and secondary sources of obsidian. Primary sources occur within the south-east extension of the Plio-Quaternary volcanic chain that runs from Copahue volcano through Pino Hachado. Secondary sources include river-bed gravels within the valleys of Arroyo Cochicó Grande and Río Kilca as far south as where this river joins with Río Aluminé, and the Quaternary fluvial-glacial sediments cut by the valley of Río Covunco as far east as Portada Covunco. Visually variable obsidians from these two secondary sources include homogeneous black and grey-translucent types, porphyritic and banded types, and an abundant quantity of oxidized red and black obsidian. However, all these visually distinct obsidians have similar and unique chemistry, with Ba between 220 and 340ppm, different from any other obsidians previously reported from Neuquén, which all have Ba>500ppm, as do obsidians from sources to the north in Mendoza and to the west in Chile. This chemical distinctive obsidian has been exploited and transported over a wide area, beginning prior to 4000 bp, and occurs in local archaeological sites, as well as sites ≥ 300km to the north-east in La Pampa Province, ~430km to the south in Chubut Province, and >75km to the west across the Andean drainage divide in Chile.Fil: Stern, C. R.. State University of Colorado at Boulder; Estados UnidosFil: Pereda, I.. No especifíca;Fil: Aguerre, Ana Margarita. Universidad de Buenos Aires. Facultad de Filosofía y Letras. Instituto de Arqueología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Optically Induced Modulation of a Laser Beam in Nematic Liquid Crystals Structures

In this paper we report the experimental results obtained when an He-Ne laser beam crosses an MBBA homeotropic sandwich structure and is modulated by the influence of another laser beam, in our case an Ar+ laser, crossing through the same region. We extend some results previously reported by us1 2 concerning the influence of the ratio of the diameters of the laser beams on the modulation characteristics. A theoretical model, based on the one reported in Ref6 , shows good agreement with the experimental results. If the Ar+ laser is intensity chopped, the resulting He-Ne diffracted image is also intensity modulated. The highest frequency observed has been 500 p. p. s

Les femmes et le liège - Réflexions sur le symbolisme de la hache à démascler et de la machine

Dans l´univers de la filière du liège, le rôle de la femme a été traditionnellement réduit à des tâches très concrètes dans la chaîne de production. Actuellement, certaines activités comme la levée du liège à la hache, restent toujours fermées aux femmes qui, en revanche, sont les principales protagonistes d’actions traditionnelles comme le triage des bouchons dans les usines. De nouveaux champs de l’industrie, de la recherche et du commerce apparaissent et se multiplient, qui ouvrent la voie à un avenir attirant pour cette ressource que constitue le liège, et dont les principaux promoteurs sont les femmes travaillant comme ouvrières, designers, responsables de laboratoire… ou tout simplement entrepreneuses. L´article que nous présentons propose de développer une campagne de communication portant sur le liège, à travers l’étude et la divulgation du rôle des femmes dans ce secteur, en étudiant leur façon de travailler et de se mettre en relation avec leurs homologues masculins. Nous avons choisi d’effectuer une étude historique comparative, en analysant les ressemblances mais aussi et surtout les dissemblances entre les manières de travailler des professionnels de sexe féminin de cette filière, et leur possible dépendance vis-à-vis de la façon de travailler des hommes

Acte d´investidura del Professor José Antonio Martín Pereda com a Doctor honoris causa de la Universitat Politècnica de Catalunya

Se recogen los discursos pronunciados en el acto de investidura como Doctor Honoris Causa de D. José Antonio Martín Pereda por la Universidad Politécnica de Cataluñ

Pilas y acumuladores comerciales (y II). Sistemas secundarios y especiales

Con este segundo capítulo se completa esta pequeña serie dedicada a pilas y acumuladores comerciales. Se abordan aquí con cierta extensión los sistemas especiales, de gran interés y poco conocidos generalmente. El resto del capítulo se dedica a acumuladores

Victimización infanto-juvenil en España: Una revisión sistemática de estudios epidemiológicos

Con el objetivo de conocer el estado de la investigación en España sobre la victimización de menores, se ha llevado a cabo una revisión sistemática de aquellas publicaciones que hayan proporcionado tasas de victimización de menores españoles, a partir de los propios reportes de éstos. Se realizó una búsqueda electrónica en las bases de datos Medline, PsycINFO, SciELO, Scopus y Latindex mediante terminología relativa a la infancia, la victimización y la procedencia geográfica de la muestra de estudio. Se seleccionaron 61 artículos, publicados entre el año 1994 y el 2010, en diversas revistas nacionales y, principalmente, sobre experiencias de victimización por iguales. Los trabajos españoles se centran, de forma mayoritaria, en una única forma de victimización, evaluada con instrumentos diversos y no adaptados a nuestro contexto sociocultural, lo que dificulta conocer la incidencia de otros tipos de violencia y la comparativa con trabajos internacionales

Assessing resilience in adolescence: The Spanish adaptation of the Adolescent Resilience Questionnaire

The concept and assessment of resilience have attracted considerable attention in recent years, but none of the instruments developed to measure resilience in adolescents have been adapted to the Spanish context. The Adolescent Resilience Questionnaire (ARQ) provides a comprehensive and multidimensional assessment of the resources associated with resilience in adolescents. This study analyzes the psychometric properties of the ARQ. Participants included a community sample of 1101 Spanish adolescents (53.5 % boys) aged 1217 years (M = 14.51; SD = 1.755). Results confirm the factor structure based on 12 scales. Internal consistency was generally adequate (between .60 and .84), although the unacceptable coefficient for the Empathy/Tolerance scale (α = .38) means that this scale needs to be revised for the Spanish context. Relationships between ARQ scales and psychopathology were in the expected direction and magnitude. Some gender differences were observed, with higher scores for boys on Confidence and Negative cognition. The Spanish version of the ARQ can help to identify personal characteristics associated with resilience and signs of positive engagement with family, peers, school, and the community. It can identify those adolescents most likely to show resilience in response to adversity, as well as those who may be vulnerable under situations of stress