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UV Distributed Bragg reflectors were fabricated by a two-step thermal oxidation process over porous silicon multilayers (PS-ML), which were prepared by room-temperature electrochemical anodization of silicon wafers. The optical behavior of the PS-ML before and after oxidation was studied by reflectance measurements. It was observed an UV shift from 430 to 300 nm in the peak of the reflectance spectrum after oxidation of the PS-ML. This was attributed to the presence of silicon oxide over the surface of the silicon filaments. Such oxide also reduced the refractive index of each porous silicon monolayer. The bandgap of the PS-ML was calculated by the Kubelka-Munk approximation, which showed an increase in the bandgap from 3.11 to 4.36 eV after the thermal oxidation process. It was suggested that the observed optical response could opens the possibility of fabrication of UV optoelectronic devices based entirely in the silicon technology.

AbstractRöpke is considered one of the most prominent Ordoliberal economists. The objective of this work is to analyse the dissemination of Röpke’s works, within Spain, through diverse institutions: Instituto de Estudios Políticos, Revista de Occidente, Sociedad de Estudios y Publicaciones, CSIC and Fundación Villalonga. Most of these works appeared between 1946 and 1963. From 1976, after the Franco Dictatorship, some of his books were reissued. Grouped by topics, the main lines of argument exposed by Röpke are perceived as: Monetary Policy, Social Policy, International and European Economic Order, and the performance of small and medium-sized companies, within the economy. [ABSTRACT FROM AUTHOR]

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Las técnicas de laboratorio de análisis hormonales han experimentado grandes progresos en las últimas décadas, actualmente se pueden realizar determinaciones hormonales con gran precisión y automatización, sin embargo, existen muchos elementos que es necesario tener en consideración al momento de interpretar un examen hormonal. El elegir el examen adecuado para la condición que estamos estudiando, el conocer sus limitaciones y potenciales falsos positivos y negativos es parte del conocimiento que es fundamental tener como clínicos. En este artículo se pretende entregar una breve revisión de las principales determinaciones hormonales, orientado a aspectos que puedan ser de utilidad al médico no especialista en su práctica clínica.

El ultrasonido endoscópico (EUS) ha revolucionado el diagnóstico y el manejo de muchas patologías de la vía digestiva, particularmente la patología pancreática, convirtiéndose en un examen prácticamente imprescindible en el abordaje diagnóstico y terapéutico de un paciente con un problema de páncreas. Es necesario dejar en claro que el método no es único y que para lograr una sensibilidad alta y cumplir el objetivo de realizar lo más adecuado, debe sumarse a otros métodos de acuerdo a cada caso, como la ecografía, la tomografía axial computarizada (TAC), la resonancia magnética (MRI) en sus diferentes modalidades, y las pruebas del laboratorio clínico microbiológico y patología. En este artículo se revisarán algunos casos de enfermedades evaluadas con este método, que muestran por qué el EUS, es una herramienta clave para el médico de urgencias y de consulta externa, el internista, el cirujano, el médico del servicio hospitalario y el personal de salud en general, al momento de definir, clasificar y orientar el manejo de determinadas patologías en el tubo digestivo. El EUS es una importante ayuda y no debe ser extraña al personal médico, debe tenerla presente junto a las demás pruebas diagnósticas en patología pancreática. Se señalarán los aspectos más relevantes en cada caso y las indicaciones del EUS.

During the last few years, an important element in the improvement of the molecular biology techniques has been the necessity for availability of high quality and functionality DNA. Several DNA extraction procedures with different results in both performance and quality, have been proposed. In this study our objective was to determine the most reliable extraction method that balances DNA quantity, and to assess the sample quantification of the fluorometric DNA quantification methods. For this, blood extracted by venopunction from 20 healthy volunteers was used to obtain DNA from buffy coat, and 4 commercial DNA extraction kits were assessed as well as two fluorometric DNA quantification methods with protocols of different complexity. Results suggest that manual methods achieve higher quality and larger yields of DNA. DNA purity obtained with the 4 extraction kits evaluated through the 260/280 and 260/230 ratio showed that the Qiacube kit fulfilled the criteria established in this work, followed very close by the Flexigene kit. On the other hand, the fluorometric DNA methods used in the samples quantification showed a higher variability when using QuantiFlour method, obtaining better results probably due to the simplicity of this protocol. [ABSTRACT FROM AUTHOR]