Insulator-to-metal transition in vanadium supersaturated silicon: variable-range hopping and Kondo effect signatures

We report the observation of the insulator-to-metal transition in crystalline silicon samples supersaturated with vanadium. Ion implantation followed by pulsed laser melting and rapid resolidification produce high quality single-crystalline silicon samples with vanadium concentrations that exceed equilibrium values in more than 5 orders of magnitude. Temperature-dependent analysis of the conductivity and Hall mobility values for temperatures from 10K to 300K indicate that a transition from an insulating to a metallic phase is obtained at a vanadium concentration between 1.1 × 10^(20) and 1.3 × 10^(21) cm^(−3) . Samples in the insulating phase present a variable-range hopping transport mechanism with a Coulomb gap at the Fermi energy level. Electron wave function localization length increases from 61 to 82 nm as the vanadium concentration increases in the films, supporting the theory of impurity band merging from delocalization of levels states. On the metallic phase, electronic transport present a dispersion mechanism related with the Kondo effect, suggesting the presence of local magnetic moments in the vanadium supersaturated silicon material.

En torno a la imagen literaria de Alfonso V de Aragón: Fortún García de Ercilla y su traducción castellana del De dictis de Antonio Beccadelli. Edición y estudio

Alfonso V of Aragon (1396-1458), who won from his contemporaries the title “the Magnanimous”, became one of the most brilliant fifteenth century monarchs, not only because of being a shrewd politician and king of one of the main kingdoms in the Iberian Peninsula, but also due to his cultural activity. Thanks to him the Aragonese territories were extended throughout the Mediterranean up to Naples, where he established a magnificent court that turned into maybe the most remarkable centre of intellectual vitality and development of Humanism. His patronage attracted a considerable number of leading poets of the period, as well as the most important Italian humanists. The presence of so many writers and outstanding scholars, together with the academic environment that the monarch encouraged, promoted an enormous literary production in four languages: Latin, Spanish, Catalan and Italian. Additionally, the valuable library gathered by the king and the Academy founded in order to spread knowledge illustrate part of his intellectual concerns. This way, through his love to literature and generosity to men of letters, Alfonso the Magnanimous boosted the culture of that time. The principal protagonist in the cultural activities of the circle of erudites formed around the sovereign was Antonio Beccadelli, called Panormita (1394-1471). He, one of the most prominent personalities of Italian Humanism, assumed the role of main royal advisor. His work De dictis et factis Alphonsi regis (The sayings and deeds of king Alfonso), which will be studied in our dissertation, became a very popular text about Alfonso’s personality, as a kind of biography based on anecdotes of the Magnanimous’ life by way of exempla to be imitated. The success of these episodes lasted for a long time and they are appreciated even nowadays. The work was valued as specula principum and had great impact in sixteenth century, when De dictis was republished several times and translated from Latin into Spanish. One of these translations, the one by Fortún García de Ercilla, caught our interest since it is in a manuscript signed by Ercilla himself and this version is still unpublished...

El teatro cómico de Enrique García Álvarez

Enrique García Álvarez (Madrid, 1883-1931) belonged to the group of writers who stood out in the late nineteenth century and early twentieth in what was known as “género chico”, label used to oppose this kind of theater to the dramaturgy considered serious. It was composed of brief and comic works whose intention was to generate a fun time for the spectators. Our author was one of the leading representatives and his numerous creations appeared profusely in the posters of the theaters per hour. In the twentieth century, he adapted to the new forms imposed on the scene. Despite his enormous fame at the time, nowadays Enrique García Álvarez remains completely unknown, not only in the eyes of the general public but also to the more knowledgeable circles of our literature. Studies of his dramatic work are almost nonexistent and basically limited to their collaborations with other authors who had more luck as Arniches or Muñoz Seca. The purpose of this thesis is, therefore, to complete a thorough study of the figure and production of Enrique García Álvarez, as well as its impact on the literature. The opening chapter is a reconstruction of the life and work of the author. In the following chapters, we proceeded to the analysis of structural features such as theme, time, space, and characters of his dramatic world. At the end of these pages, we have included a photographic appendix that illustrates some moments of his personal and professional career. We have also developed appendices to classify his librettos chronologically, by collaborator and by genre...

Myocardial edema after ischemia/reperfusion is not stable and follows a bimodal pattern: Imaging and histological tissue characterization

It is widely accepted that edema occurs early in the ischemic zone and persists in stable form for at least 1 week after myocardial ischemia/reperfusion. However, there are no longitudinal studies covering from very early (minutes) to late (1 week) reperfusion stages confirming this phenomenon. This study sought to perform a comprehensive longitudinal imaging and histological characterization of the edematous reaction after experimental myocardial ischemia/reperfusion. The study population consisted of 25 instrumented Large-White pigs (30 kg to 40 kg). Closed-chest 40-min ischemia/reperfusion was performed in 20 pigs, which were sacrificed at 120 min (n = 5), 24 h (n = 5), 4 days (n = 5), and 7 days (n = 5) after reperfusion and processed for histological quantification of myocardial water content. Cardiac magnetic resonance (CMR) scans with T2-weighted short-tau inversion recovery and T2-mapping sequences were performed at every follow-up stage until sacrifice. Five additional pigs sacrificed after baseline CMR served as controls. In all pigs, reperfusion was associated with a significant increase in T2 relaxation times in the ischemic region. On 24-h CMR, ischemic myocardium T2 times returned to normal values (similar to those seen pre-infarction). Thereafter, ischemic myocardium-T2 times in CMR performed on days 4 and 7 after reperfusion progressively and systematically increased. On day 7 CMR, T2 relaxation times were as high as those observed at reperfusion. Myocardial water content analysis in the ischemic region showed a parallel bimodal pattern: 2 high water content peaks at reperfusion and at day 7, and a significant decrease at 24 h. Contrary to the accepted view, myocardial edema during the first week after ischemia/reperfusion follows a bimodal pattern. The initial wave appears abruptly upon reperfusion and dissipates at 24 h. Conversely, the deferred wave of edema appears progressively days after ischemia/reperfusion and is maximal around day 7 after reperfusion.

Preparation of manganese oxide - graphite electrodes by electrophoretic deposition

Manganese oxide is a promising active material for supercapacitors (SCs) with pseudocapacitance due to its high capacitance and its environmentally friendly character. This paper deals with the preparation of electrodes for supercapacitors consisting of manganese oxide supported onto graphite by electrophoretic deposition. Manganese oxide powders were characterized and dispersed in water by controlling the colloidal and rheological behavior in order to obtain stable suspensions. Optimized manganese oxide suspensions were deposited onto graphite electrodes by electrophoretic deposition. The deposited mass per unit area in the electrodes was optimized by controlling the applied current density and the deposition time. It has been demonstrated that the introduction of a binder helped to improve the adherence to graphite; otherwise the deposit thickness obtained by EPD is limited and no films can be obtained by simply dipping. These conditions allowed us to obtain more homogeneous deposits with higher specific energy than without binder.

Association of myocardial T1-mapping CMR with hemodynamics and RV performance in pulmonary hypertension

Early detection of right ventricular (RV) involvement in chronic pulmonary hypertension (PH) is essential due to prognostic implications. T1 mapping by cardiac magnetic resonance (CMR) has emerged as a noninvasive technique for extracellular volume fraction (ECV) quantification. We assessed the association of myocardial native T1 time and equilibrium contrast ECV (Eq-ECV) at the RV insertion points with pulmonary hemodynamics and RV performance in an experimental model of chronic PH. Right heart catheterization followed by immediate CMR was performed on 38 pigs with chronic PH (generated by surgical pulmonary vein banding) and 6 sham-operated controls. Native T1 and Eq-ECV values at the RV insertion points were both significantly higher in banded animals than in controls and showed significant correlation with pulmonary hemodynamics, RV arterial coupling, and RV performance. Eq-ECV values also increased before overt RV systolic dysfunction, offering potential for the early detection of myocardial involvement in chronic PH.

Efficacy and safety of out-of-hospital intravenous metoprolol administration in anterior ST-segment elevation acute myocardial infarction: insights from the METOCARD-CNIC trial

We seek to examine the efficacy and safety of prereperfusion emergency medical services (EMS)–administered intravenous metoprolol in anterior ST-segment elevation myocardial infarction patients undergoing eventual primary angioplasty. This is a prespecified subgroup analysis of the Effect of Metoprolol in Cardioprotection During an Acute Myocardial Infarction trial population, who all eventually received oral metoprolol within 12 to 24 hours. We studied patients receiving intravenous metoprolol by EMS and compared them with others treated by EMS but not receiving intravenous metoprolol. Outcomes included infarct size and left ventricular ejection fraction on cardiac magnetic resonance imaging at 1 week, and safety by measuring the incidence of the predefined combined endpoint (composite of death, malignant ventricular arrhythmias, advanced atrioventricular block, cardiogenic shock, or reinfarction) within the first 24 hours. From the total population of the trial (N=270), 147 patients (54%) were recruited during out-of-hospital assistance and transferred to the primary angioplasty center (74 intravenous metoprolol and 73 controls). Infarct size was smaller in patients receiving intravenous metoprolol compared with controls (23.4 [SD 15.0] versus 34.0 [SD 23.7] g; adjusted difference –11.4; 95% confidence interval [CI] –18.6 to –4.3). Left ventricular ejection fraction was higher in the intravenous metoprolol group (48.1% [SD 8.4%] versus 43.1% [SD 10.2%]; adjusted difference 5.0; 95% CI 1.6 to 8.4). Metoprolol administration did not increase the incidence of the prespecified safety combined endpoint: 6.8% versus 17.8% in controls (risk difference –11.1; 95% CI –21.5 to –0.6). Out-of-hospital administration of intravenous metoprolol by EMS within 4.5 hours of symptom onset in our subjects reduced infarct size and improved left ventricular ejection fraction with no excess of adverse events during the first 24 hours.

La aplicación del principio de transparencia en los procesos de selección en la contratación estatal colombiana a través del Secop

El Principio de Transparencia aplicado a los procesos de selección en la contratación estatal colombiana a través del SECOP es un rito confesional, es decir, debe estar presente tanto y desde la licitación pública como y hasta en la contratación directa, pues ese ‘derecho de acceso de los ciudadanos a la información pública y la transparencia de la actuación política y administrativa que a través de él se asegura son considerados hoy con toda razón (…) elementos esenciales para la formación de una opinión pública libre y garantías imprescindibles para el buen funcionamiento de las instituciones y para el ejercicio de los derechos fundamentales sobre los que descansa todo sistema democrático’

Evaluación de las propiedades clinimétricas de la escala POSAS y su aplicación en pacientes de la Fundación del Quemado en Bogotá

•Objetivos: Se tradujo, adaptó y evaluaron las propiedades clinimétricas de la escala POSAS en pacientes con cicatrices hipertróficas (CHT) y queloides (CQ) cómo secuelas de quemadura, que fueron manejados con Z plastias en la Fundación del Quemado en Bogotá (Colombia), entre Junio de 2015 a Abril de 2016. •Métodos: Estudio de evaluación de las propiedades clinimétricas de una escala. Se hizo una traducción y adaptación transcultural siguiendo el método de traducción-retrotraducción. Se aplicó el instrumento adaptado a cincuenta y dos pacientes (n=52) antes y después de la intervención quirúrgica. Se evaluó la validez, confiabilidad, sensibilidad al cambio y la utilidad de la escala. •Resultados: Se hallaron diferencias significativas en los puntajes obtenidos del Observador y del Paciente, antes y después de la intervención quirúrgica (p<0.000); a excepción de prurito. La escala POSAS demostró ser altamente confiable para la Escala del Observador y del Paciente (α = 0.912 y 0.765). Hubo alta correlación en las evaluaciones de dos observadores para las variables ordinales de la Escala del Observador (r>0.6). La concordancia entre las evaluaciones de dos observadores para las variables categóricas de la Escala del Paciente fue buena para la evaluación antes de la intervención para pigmentación y relieve (κ>0.61). Se demostró que el instrumento es capaz de detectar cambios clínicos en el tiempo (p<0.0000), a excepción de prurito (p= 0.271). •Conclusiones: La escala POSAS demostró ser un instrumento válido, confiable y útil para evaluar la calidad de la cicatriz en pacientes con CHT y CQ cómo secuelas de quemadura.

Tendencia editorial UR Número 6

El Boletín Tendencia Editorial es un proyecto que nació en 2010 con motivo de la Feria Internacional del Libro de Bogotá para construir y hacer visibles diferentes saberes desde la academia y la edición. Para 2014, el cambio de periodicidad coincidió con uno de los eventos más importantes para la edición universitaria, la Feria Internacional del Libro de Guadalajara donde anualmente se realiza el encuentro de Editores Universitarios Latinoamericanos, el proyecto pasó de su fase nacional a ser pensado en red. Las líneas temáticas traspasan fronteras locales y convocan, en un mismo espacio, las voces de los gestores y especialistas, cuya labor y experiencia permiten cada día mejorar la edición universitaria, lo que posibilita acabar con el mito que concibe a la Universidad como ente ajeno a la sociedad, cuando en realidad esta es la forjadora de líderes, investigadores y emprendedores.

Propuesta de creación de la Reserva Natural Municipal El Chuval en el Municipio de El Retén, Magdalena, Colombia

Colombia se ha comprometido a nivel internacional a realizar acciones que conduzcan al país hacia el desarrollo sostenible, específicamente a proteger los recursos naturales. En línea con esta apuesta, la presente investigación propone la construcción de la Reserva Natural El Chuval, en el municipio El Retén, Magdalena. Para la construcción de dicha Reserva se realiza un diagnóstico que indica las principales características del Chuval, se identifican posibles riesgos para la conservación de sus valores ambientales, y se complementa el análisis con una propuesta de manejo que se enmarca en la metodología de Agendas Ambientales Locales desarrollada por la ONU. Pese a que el municipio es consciente de la relevancia ambiental del Chuval, aún no se han tomado decisiones definitivas para proteger esta zona, razón por la cual, la presente investigación busca llenar un vacío en el ordenamiento territorial del municipio, que fortalezca la protección de la Ciénaga Grande de Santa Marta.

Maleta pequeña y relatos cortos: Crónicas de un viajero

Este trabajo de grado es un conjunto de crónicas que carácter experiencial, desde las cuales se narran las historias que viven los turistas en sitios inhóspitos como el desierto de la Tatacoa y la selva del Amazonas. Estos textos están orientados a mostrar el desarrollo del periodismo de turismo en Colombia.