Repeatability of the subjective refraction

Actualment, l’error refractiu és considerat un problema de salut a nivell mundial. Un examen refractiu precís és vital per obtenir la millor agudesa visual possible i portar a terme correctament altres exàmens visuals. Principalment, hi han tres tipus de error refractiu; miopia, hipermetropia i astigmatisme. D’altra banda, trobem la presbícia la qual consisteix en una disminució fisiològica de la capacitat d’acomodació. La mostra d’aquest estudi consisteix en 10 pacients els quals es troben en un rang d’edat entre els 18 i els 30 anys. Només pacients sense patologies oculars han sigut examinats a l’estudi. Altrament, l’examen refractiu consisteix en un examen subjectiu partint d’un autorefractómetre binocular (WAM-5500). L’examen subjectiu s’inicia monocularment i després binocularment amb els equilibris biocular i binocular. En relació a l’anàlisi estadístic, abans d’utilitzar els test de SSPS statistics versió 22.00, hem transformat el valor d’esfera i astigmatisme a l’espai ortonormal per comparar els resultats correctament. En tots els casos un p-valor de 0.05 ha sigut considerat estadísticament significant i, s’ha considerat un 95% d’interval de confiança. L’anàlisi estadístic d’aquest estudi conclou, amb un p-valor>0.05 en el test de Wilcoxon Signed-rank, que hi ha concordança entre les dues mesures. En contraposició, les dades han resultat seguir una distribució no normal. L’objectiu i la importància d’aquest estudi és conèixer la repetibilitat d’aquest mètode de mesura de la refracció

Scattering approach to fidelity decay in closed systems and parametric level correlations

This paper is based on recent work which provided an exact analytical description of scattering fidelity experiments with a microwave cavity under the variation of an antenna coupling [K\"ober et al., Phys. Rev. E 82, 036207 (2010)]. It is shown that this description can also be used to predict the decay of the fidelity amplitude for arbitrary Hermitian perturbations of a closed system. Two applications are presented: First, the known result for global perturbations is re-derived, and second, the exact analytical expression for the perturbation due to a moving S-wave scatterer is worked out. The latter is compared to measured data from microwave experiments, which have been reported some time ago. Finally, we generalize an important relation between fidelity decay and parametric level correlations to arbitrary perturbations.Comment: 20 pages, 2 figures, research article, (v2: stylistic changes, ref. added

Influence of Nb-doping on the structural and electrical properties of lanthanum molybdates, La5.4MoO11.1

Nowadays, hydrogen is receiving a great deal of attention as an energy carrier. Commonly, it is obtained by hydrocarbons reforming, such as natural gas, coal and biomass. However, the resulting hydrogen needs to be purified to remove by-products and impurities, increasing the production costs. An alternative for hydrogen production is proton-conducting ceramics, where hydrogen separation takes place via a chemical potential gradient across the membrane.1, 2 In this work, Nb-doped La6MoO12--based compounds have been investigated as part of a new family of materials very competitive as SOFC electrolyte and hydrogen separation membranes.3 These materials, La5.4Mo1-xNbxO11.1-x/2 (x = 0.05, 0.10, 0.15 y 0.20) were synthesized by the freeze-drying precursor method and calcination conditions have been optimized to obtain single phases. A complete characterization has been carried out using X-Ray powder diffraction and scanning and transmission electron microscopy. The total conductivity was determined by complex impedance spectroscopy at different atmospheres. Different polymorphs are obtained as a function of the cooling rate and the dopant amount. The samples cooled by quenching are cubic with a fluorite-type structure (Fm3 ̅m) and the ones cooled at 50 y 0.5 ºC•min-1 are rhombohedral (R1 and R2 polymorphs). For niobium contents higher than x = 0.10 the R1 polymorph is stabilised at cooling rates equal or inferior to 50 ºC•min-1. For all three series, the incorporation of niobium into La5.4MoO11.1 increases the conductivity, reaching the best values for x=0.10 and the sample obtained by quenching.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Human activity recognition from object interaction in domestic scenarios

This paper presents a real time approach to the recognition of human activity based on the interaction between people and objects in domestic settings, specifically in a kitchen. Regarding the procedure, it is based on capturing partial images where the activity takes place using a colour camera, and processing the images to recognize the present objects and their location. For object description and recognition, a histogram on rg chromaticity space has been selected. The interaction with the objects is classified into four types of possible actions; (unchanged, add, remove or move). Activities are defined as recipes, where objects play the role of ingredients, tools or substitutes. Sensed objects and actions are then used to analyze in real time the probability of the human activity performed at a particular moment in a continuous activity sequence.Peer ReviewedPostprint (author's final draft

Effect of preparation conditions on the polymorphism and transport properties of lanthanum molybdates

In this work, La6MoO12-based compounds were investigated as part of a new family of materials very competitive as hydrogen separation membranes [1,2]. La5.4MoO11.1 was synthesized by the freeze-drying precursor method and the calcination conditions were optimized in order to obtain single phases. Several cooling rates were applied and different polymorphs were obtained: a simple cubic fluorite symmetry (Fm-3m) for the sample cooled by quenching, and two different rhombohedral (R-3) space groups for the samples cooled at 50 ºC•min-1 and 0.5 ºC•min-1 (see Figure below). For the quenched sample, the Rietveld refinement was satisfactory in a Fm-3m space group. For the other two compositions no structural model was available and were indexed in a R-3 space group, however some small reflections were not given any intensity by the model used. Transmission electron microscopy confirmed the presence of superstructures for those samples. All ceramic materials were obtained with relative densities close to 100% after sintering at 1500 ºC. Stability studies demonstrated that all three polymorphs were stable in oxidizing and reducing conditions at 800 ºC for 48 hours. The three samples present a significant proton contribution to the conductivity at temperatures lower than 800 ºC. These results were confirmed by thermogravimetric analysis. The highest conductivity values were observed for the samples prepared by quenching. The three polymorphs display a small p-type electronic contribution to the overall conductivity in oxidizing conditions and n-type electronic one in very reducing conditions, much more significant for the samples cooled by quenching and at 50 ºC•min-1.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Inserción global, desarticulación y competitividad en el sector electromecánico mexicano: un análisis estructural

En este artículo se analiza el funcionamiento dual del sector electromecánico mexicano en el período 1994-2008, diferenciando del resto las actividades globalizadas. Al estimar la productividad laboral de 52 clases industriales, se halla un crecimiento de la heterogeneidad estructural sobre todo en el lapso 1994-2001, concomitante de la progresiva concentración de las mejoras técnicas y organizativas en un número reducido de empresas filiales de transnacionales del ensamblaje automotriz. Otro resultado obtenido mediante la utilización de una técnica diferencial-estructural es la ausencia de un cambio estructural significativo. Finalmente, la aplicación de una extensión de la metodología para evaluar la competitividad —elaborada por la Comisión Económica para América Latina y el Caribe (cepal)— a una segunda base de datos en que se reclasifican 1.345 productos del comercio exterior, permite contrastar estas transformaciones con el dinamismo de las redes globales de producción en que se insertan las empresas líderes del sector en México

Propuestas en el trabajo educativo para fomentar la transversalidad de la enseñanza

Castellà: El objetivo de este trabajo es buscar una nueva manera de impartir clases en el primer ciclo de la ESO, más concretamente y debido a la experiencia vivida en un IES de Barcelona, en el primer ciclo de secundaria. Presentamos un análisis concreto sobre el IES mencionado, estudiando las características de las aulas, los horarios y su distribución, el profesorado, los métodos de atención a la diversidad, los procesos de evaluación utilizados y los recursos. Finalmente mostramos el resultado de una encuesta realizada en dos de las cuatro líneas de primero de ESO. Presentamos diversas pedagogías y metodologías reconocidas y utilizadas en otras escuelas. Estudiamos sus características, ventajas y mecanismos frente a la atención a la diversidad. Hablamos de la importancia de dar a elegir al alumno según sus capacidades e intereses para facilitar su desarrollo, con el objetivo principal de formar gente competente. Partiendo del estudio anterior y basándonos en el aprendizaje basado en proyectos, el trabajo cooperativo y las inteligencias múltiples explicamos nuestra propuesta. Redefinimos el rol del tutor asignándole más responsabilidades y aumentando su implicación en el aula, además de asignarle un rol de coordinador y director del proyecto propuesto. Proponemos un nuevo horario que facilite la implantación de nuestra propuesta y mostramos la necesidad de un trabajo colaborativo en el quipo directivo y docente del IES. Proponemos como ejemplo un trabajo cooperativo para trabajar de manera transversal diversas materias facilitando a cada alumno la elección del campo que más le interesa o mejor se ajusta a sus capacidades innatas. Buscamos dividir la clase en diferentes roles con trabajos cooperativos para conseguir un mismo objetivo; hacer un proyecto. Especificaremos los diferentes métodos evaluativos que usamos en la propuesta u sus objetivos

Is it possible to upgrade in global value chains? A comparison between industrial policy in Mexico and the Asian experience

This article analyzes the industrial policy implemented in Mexico as a result of the trade liberalization, highlighting its role in the configuration of an industrial specialization pattern that revolved around inbond assembly activities and whose main feature was manufactured goods with low value added and little local technological knowledge. By contrast, a synthesis of public measures whit broughr about the upgrading of manufacturing activities in Taiwan gives rise to a debate about the relevance of the State as a promoter of productive development adn questions the possibilities of developing countries to move up within international manufacturing linkages