Reliability evaluation of III-V concentrator solar cells

Concentrator solar cells have been proposed as an interesting way of reducing the cost of photovoltaic electricity. However, in order to compete with conventional solar modules it is necessary not only to reduce costs but also to evaluate and increase the present reliability. Concentrator solar cells work at higher temperature, solar radiation and current stress than conventional solar cells and a carefully reliability analysis is needed. In this paper a reliability analysis procedure, that is being developed, is presented

Design of Polymeric Nanocapsules for Intranasal Vaccination against Mycobacterium Tuberculosis: Influence of the Polymeric Shell and Antigen Positioning.

Tuberculosis (TB) is the leading cause of death from a single infectious microorganism and Bacillus Calmette Guerin (BCG), the only authorized vaccine, does not confer protection against pulmonary TB. Based on the hypothesis that mucosal protection could help to prevent the infection at the site of entrance, the objective of this work was to develop an intranasal vaccine against Mycobacterium tuberculosis (Mtb), the microorganism that causes TB. Our approach consisted of the use of polymeric nanocapsules (NCs) with an oily core and a polymer shell made of chitosan (CS) or inulin/polyarginine (INU/pArg). The immunostimulant Imiquimod, a Toll-like receptor-7 (TLR-7) agonist, was encapsulated in the oily core and a fusion protein, formed by two antigens of Mtb, was absorbed either onto the NC surface (CS:Ag and INU:pArg:Ag) or between two polymer layers (INU:Ag:pArg) in order to assess the influence of the antigen positioning on the immune response. Although CS NCs were more immunostimulant than the INU/pArg NCs in vitro, the in vivo experiments showed that INU:pArg:Ag NCs were the only prototype inducing an adequate immunoglobulin A (IgA) response. Moreover, a previous immunization with BCG increased the immune response for CS NCs but, conversely, decreased for INU/pArg NCs. Further optimization of the antigen and the vaccination regime could provide an efficacious vaccine, using the INU:pArg:Ag NC prototype as nanocarrier

Towards the characterization of individual users through Web analytics

We perform an analysis of the way individual users navigate in the Web. We focus primarily in the temporal patterns of they return to a given page. The return probability as a function of time as well as the distribution of time intervals between consecutive visits are measured and found to be independent of the level of activity of single users. The results indicate a rich variety of individual behaviors and seem to preclude the possibility of defining a characteristic frequency for each user in his/her visits to a single site.Comment: 8 pages, 4 figures. To appear in Proceeding of Complex'0

Sequential P3 effects in a Posner’s spatial cueing paradigm: Trial-by-trial learning of the predictive value of the cue

The neurocognitive consequences of correct or incorrect spatial prediction in a sequential S1–S2 paradigm were assessed. Sequential dependence on previous trial outcome (valid or invalid) was assessed by late Event-Related Potentials (ERPs) and behavioural responses. Two different experiments were performed, situating the target in the vertical (Experiment 1) or in the horizontal (Experiment 2) meridian. RTs and late positivities (P3a and P3b) were recorded. ERPs showed that posterior positivity (probably a P3b) was greater in invalid–valid trials than in valid–valid trials but lower than in valid– invalid trials. However, at the frontal electrodes, late positivity (probably a P3a) only appeared in valid–invalid trials, indicating that invalid trials are analyzed as novel-like stimuli. The P3b results suggest trial-by-trial learning of the predictive value of the cue, which needs to be updated as indicated by the pattern of P3b amplitudes: valid–invalid > invalid–valid > valid–valid.Ministerio de Educación y Ciencia (España)Junta de Andalucí

Continuous and Localized Mn Implantation of ZnO

We present results derived from continuous and localized 35 keV (55)Mn(+) ion implantations into ZnO. Localized implantations were carried out by using self-ordered alumina membranes as masks leading to ordered arrays of implanted volumes on the substrate surfaces. Defects and vacancies in the small implantation volumes of ZnO were generated due to the implantation processes besides the creation of new phases. Rapid thermal annealing was applied in the case of continuous implantation. The samples were characterized by HRSEM, GIXRD, Raman spectroscopy and RBS/C. Magnetic characterization of the samples pointed out appreciable differences among the samples obtained by the different implantation methods. This fact was mainly attributed to the different volume/surface ratios present in the implanted zones as well as to the increase of Mn atom concentrations along the grain frontiers in the nanostructured surfaces. The samples also showed a ferromagnetic transition phase at temperature value higher than room temperature

A Step Closer to Elastogenesis on Demand; Inducing Mature Elastic Fibre Deposition in a Natural Biomaterial Scaffold

Elastic fibres play a key role in bodily functions where fatigue resistance and elastic recovery are necessary while regulating phenotype, proliferation and migration in cells. While in vivo elastic fibres are created at a late foetal stage, a major obstacle in the development of engineered tissue is that human vascular smooth muscle cells (hVSMCs), one of the principal elastogenic cells, are unable to spontaneously promote elastogenesis in vitro. Therefore, the overall aim of this study was to activate elastogenesis in vitro by hVSMCs seeded in fibrin, collagen, glycosaminoglycan (FCG) scaffolds, following the addition of recombinant human tropoelastin. This combination of scaffold, tropoelastin and cells induced the deposition of elastin and formation of lamellar maturing elastic fibres, similar to those found in skin, blood vessels and heart valves. Furthermore, higher numbers of maturing branched elastic fibres were synthesised when a higher cell density was used and by drop-loading tropoelastin onto cell-seeded FCG scaffolds prior to adding growth medium. The addition of tropoelastin showed no effect on cell proliferation or mechanical properties of the scaffold which remained dimensionally stable throughout. With these results, we have established a natural biomaterial scaffold that can undergo controlled elastogenesis on demand, suitable for tissue engineering applications

Innovaciones en torno a la disminución de presencialidad en el proceso docente

El presente trabajo constituye una reflexión a partir de las experiencias desarrolladas en la Universidad de Oriente acerca de la factibilidad del perfeccionamiento de los estudios regulares de pregrado desde el punto de vista de disminución de la presencialidad. Este perfeccionamiento se ha desarrollado a partir de la combinación de sesiones presenciales con la metodología propia de la enseñanza a distancia. En un proceso docente en que están presentes un aula real y una virtual, en las cuales, el colectivo estudiantil desarrolla sus actividades de manera significativa a través de proyectos, estudios de casos o solución de problemas; según corresponda a la especialidad que se cursa y donde el profesor presencial además cumplirá el rol de tutor. El principal aporte logrado está en haber desarrollado una estrategia para la utilización de la Computación y TIC en el Proceso Docente Educativo que se desarrolla en los cursos presenciales de nuestra universidad a partir de las experiencias desarrolladas básicamente en las carreras de ingeniería de perfil eléctrico desde el curso académico 2000-2001 en el desarrollo de sitios Web educativos, materiales docentes multimedia, cursos en línea y las metodologías y modelos desarrollados en el transcurso de esas experiencias.Eje: Educación universitaria: Experiencias uso NTICRed de Universidades con Carreras en Informática (RedUNCI

Focal-plane generation of multi-resolution and multi-scale image representation for low-power vision applications

Comunicación presentada al "XXXVII Infrared Technology and Applications" celebrado en Orlando (USA) el 25 de Abril del 2011.Early vision stages represent a considerably heavy computational load. A huge amount of data needs to be processed under strict timing and power requirements. Conventional architectures usually fail to adhere to the specifications in many application fields, especially when autonomous vision-enabled devices are to be implemented, like in lightweight UAVs, robotics or wireless sensor networks. A bioinspired architectural approach can be employed consisting of a hierarchical division of the processing chain, conveying the highest computational demand to the focal plane. There, distributed processing elements, concurrent with the photosensitive devices, influence the image capture and generate a pre-processed representation of the scene where only the information of interest for subsequent stages remains. These focal-plane operators are implemented by analog building blocks, which may individually be a little imprecise, but as a whole render the appropriate image processing very efficiently. As a proof of concept, we have developed a 176x144-pixel smart CMOS imager that delivers lighter but enriched representations of the scene. Each pixel of the array contains a photosensor and some switches and weighted paths allowing reconfigurable resolution and spatial filtering. An energy-based image representation is also supported. These functionalities greatly simplify the operation of the subsequent digital processor implementing the high level logic of the vision algorithm. The resulting figures, 5.6m W@30fps, permit the integration of the smart image sensor with a wireless interface module (Imote2 from Memsic Corp.) for the development of vision-enabled WSN applications.This work is partially funded by the Andalusian regional government (Junta de Andalucía-CICE) through project 2006-TIC-2352 and the Spanish Ministry of Science (MICINN) through project TEC 2009-11812, co-funded by the European Regional Development Fund, and also supported by the Office of Naval Research (USA), through grant N000141110312.Peer Reviewe

Estimation of some geohydrological properties in a set of monitoring wells in Mexicali Valley, B.C., Mexico

[EN] With the aim of studying the response of the water level related to variations in barometric pressure and the action of theoretical Earth tide, in a set of monitoring wells in the Mexicali Valley; are propose and implement analysis techniques in the time and frequency domain to obtain as result from the calculation of transfer functions and harmonic analysis, values of barometric efficiency and sensitivity to Earth tide, with which under conditions of theoretical static-confined response, was possible to obtain estimates of some geohydrological and geophysical properties as: porosity, specific storage, and compressibility. In five wells considered in this paper were obtained estimates of the properties of the aquifer in a state before and after an earthquake. This work has enabled a better understanding of the parameters that control the processes that occur in the study area[ES] Con el objetivo de estudiar la respuesta del nivel del agua relacionada a las variaciones de la presión barométrica y a la acción de la marea terrestre teórica, en pozos de monitoreo en el Valle de Mexicali. Técnicas de análisis en los dominios del tiempo y la frecuencia son planteadas e implementadas, para obtener como resultado del cálculo de funciones de transferencia y análisis de armónicos, valores de eficiencias barométrica y de sensibilidad a la marea terrestre, con los cuales bajo condiciones de respuesta confinada–estática teórica, fue posible obtener estimaciones de algunas propiedades geohidrológicas y geofísicas como: porosidad, almacenamiento específico, y compresibilidad. En cinco pozos considerados en este trabajo se obtuvieron estimaciones de las propiedades del acuífero en un estado previo y posterior a un sismo. Este trabajo ha permitido un mejor conocimiento de los parámetros que controlan los procesos que suceden en la zona de estudioLos autores agradecen sinceramente los comentarios y sugerencias realizadas por cada uno de los revisores. Este trabajo ha sido financiado por recursos otorgados por el Consejo Nacional de Ciencia y Tecnología, CONACYT, México, a través de la beca para estudios de posgrado No. 234622, Mario Alberto Fuentes Arreazola.Fuentes-Arreazola, MA.; Vázquez-González, R. (2016). Estimación de algunas propiedades geohidrológicas en un conjunto de pozos de monitoreo en el Valle de Mexicali, B.C., México. Ingeniería del Agua. 20(2):87-101. https://doi.org/10.4995/ia.2016.4389SWORD87101202Agnew, D. C. (2012). SPOTL: Some programs for ocean-tides loading. Technical Report, Scripps Institution of Oceanography, La Jolla, California, USA.Álvarez-Rosales, J. (1999). Aspectos generales sobre geohidrología en Cerro Prieto, B. C., México. Geotermia,15(1), 05-10.Bendat, J. 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Some basic stress diffusion solutions for fluid-saturated elastic porous media with compressible constituents. Reviews of Geophysics, 14(2), 227-241, doi:10.1029/RG014i002p00227Roeloffs, E. A. (1988). Hydrological precursors to earthquakes: A review. Pure and Applied Geophysics, 126(2), 177-209, doi:10.1007/BF00878996Rojstaczer, S. (1988a). Determination of fluid flow properties from the response of water levels in wells to atmospheric loading. Water Resources Research, 24(11), 1927-1938, doi:10.1029/WR024i011p01927Rojstaczer, S. (1988b). Intermediate period response of water levels in wells to crustal strain: sensitivity and noise level. Journal of Geophysical Research, 93(B11), 13619-13634, doi:10.1029/JB093iB11p13619Rojstaczer, S., Agnew, D. C. (1989). The influence of formation materials properties on the response of water levels in wells to Earth tides and atmospheric loading. Journal of Geophysical Research,94(B9), 12403-12411, doi:10.1029/JB094iB09p12403Rojstaczer, S., Riley, F. S. (1990). Response of the water level in a well to Earth tides and atmospheric loading under unconfined conditions. Water Resources Research,26(8), 1803-1817, doi:10.1029/WR026i008p01803Schatz, J. F. (1982). Physical processes of subsidence in geothermal reservoirs. Report No. TR82-39, Terratek, Salt Lake City, Utah, and Lawrence Berkeley Laboratory, Report LBL-14605, 136p.Solinst. (2011). Levelogger series, user guide. Solinst LTD, Canada. 72p.Somerton, W. H. (1980). Some physical properties of Cerro Prieto cores. Geothermics,9(1-2), 159-168, doi:10.1016/0375-6505(80)90029-2Van Der Kamp, G., Gale, J. E. (1983). Theory of earth tide and barometric effects in porous formations with compressible grains. Water Resources Research, 19(2), 538-544, doi:10.1029/WR019i002p00538Vázquez-González, R. (1999). Condiciones geohidrológicas del acuífero somero en la zona del campo geotérmico de Cerro Prieto. Geotermia,15(1), 11-1