Estudio por primeros principios de las propiedades estructurales y electrónicas de la multicapa CrN/GaN

In this work we perform first-principles calculations to investigate the structural and electronic properties of the 1x1 CrN/GaN multilayer. The calculations were executed in zincblende and wurtzite phase, since they are the ground states of chromium nitride CrN and gallium nitride GaN, respectively. However, we study the stability of the multilayer in the NaCl phase, in order to predict possible phase transitions. We found that the most favorable phase for the multilayer is the hexagonal wurtzite type, with possibility of passing to the NaCl phase by applying an external pressure. Our calculations indicate that the pressure of transition is 13,5 GPa. From the density of states, we found that the multilayer present a metallic behavior produced by the hybrid orbitals d-Cr and N-p that cross level Fermi.En este trabajo realizamos cálculos de primeros principios para investigar las propiedades estructurales y electrónicas de la multicapa 1x1 CrN / GaN. Los cálculos se ejecutaron en fase de zincblende y wurtzita, ya que son los estados fundamentales del nitruro de cromo CrN y el nitruro de galio GaN, respectivamente. Sin embargo, estudiamos la estabilidad de la multicapa en la fase de NaCl, para predecir posibles transiciones de fase. Descubrimos que la fase más favorable para la multicapa es el tipo de wurtzita hexagonal, con posibilidad de pasar a la fase de NaCl aplicando una presión externa. Nuestros cálculos indican que la presión de transición es de 13,5 GPa. A partir de la densidad de estados, encontramos que la multicapa presenta un comportamiento metálico producido por los orbitales híbridos d-Cr y N-p que cruzan el nivel de Fermi

Teoría de los precios. Avances en el debate contemporáneo

El propósito de este libro es mostrar a los estudiantes de economía un hecho fundamental: la teoría de los precios, hoy en día es un campo en debate sujeto a severos cuestionamientos desde cualquer punto de vista, Más aún, plantea la urgencia de incorporar este debate como una manera de entender los alcances y limitaciones que actualmente se ecuentran en cualquiera de los enfoques teóricos existentes, particularmente en aquél que aparece como dominante. El texto es una invitación a la búsqueda en un campo que, si bien no es tan notorio como otros en la economía política, resulta esencial en la formación de economistas con un sentido crítico y realista del "estado del arte" en su disciplina

Responsabilidad social y universidad

182 p.En esta colección se centra en la responsabilidad social que corresponde a las instituciones de educación superior. Así mismo , aporta al compromiso misional de la universidad de inculturar la doctrina social católica y el estudio, análisis, sensibilización y propuestas frente a las realidades culturales, políticas, económicas y sociales de Colombia. Esta obra está destinada a las comunidades académicas que orientan sus reflexiones a la proyección social de sus entes educativos.Prólogo Responsabilidad social universitaria 1· Humanizar el hábitat. Un ejemplo de responsabilidad social William Fernando Puentes González 2. Una introducción a la idea de justicia. Un debate contemporáneo ¿qué es una sociedad justa? Armando Rojas Claros 3. Acercamiento al personalismo de Emmanuel Mounier como propuesta ante la problemática de la sociedad actual Alexander Aldana Piñeros 4. La cortesía, expresión de la responsabilidad social Edilberto Cruz Espejo 5. Construcción de ciudadanía y de ciudadano: la formación del profesional incluyente Edgar Javier Garzón P. 6. Evaluación e impacto de un programa de formación humanística en instituciones educativas de la ciudad de Bogotá Katherin Hurtado Morales, Humberto Grimaldo Durán, Floralba Barrero Rivera y Alba Lucía Meneses Báez 7. Caritas in veritate: verdad y acción, un paso a la responsabilidad social en el mundo globalizado Elizabeth Duvanca Reyes 8. Doctrina Social de la Iglesia y desarrollo humano: ejemplo de responsabilidad social Giovanni Reyes Ortiz 9. La responsabilidad social universitaria desde el paradigma de la psicología comunitaria Nelly Ayala Rodríguez María Constanza del Portillo Obando María Victoria Neira Roa 10. Informática comunitaria y acciones de mejoramiento para la proyección social Jorge Fernando Bejarano Lobo 11. Responsabilidad social en la educación matemática Jacinto Eloy Puig Portal 12. Responsabilidad social. Recuento de experiencias Doris Carda de Bernal Bibliografí

Large-scale patterns of turnover and basal area change in Andean forests

General patterns of forest dynamics and productivity in the Andes Mountains are poorly characterized. Here we present the first large-scale study of Andean forest dynamics using a set of 63 permanent forest plots assembled over the past two decades. In the North-Central Andes tree turnover (mortality and recruitment) and tree growth declined with increasing elevation and decreasing temperature. In addition, basal area increased in Lower Montane Moist Forests but did not change in Higher Montane Humid Forests. However, at higher elevations the lack of net basal area change and excess of mortality over recruitment suggests negative environmental impacts. In North-Western Argentina, forest dynamics appear to be influenced by land use history in addition to environmental variation. Taken together, our results indicate that combinations of abiotic and biotic factors that vary across elevation gradients are important determinants of tree turnover and productivity in the Andes. More extensive and longer-term monitoring and analyses of forest dynamics in permanent plots will be necessary to understand how demographic processes and woody biomass are responding to changing environmental conditions along elevation gradients through this century

Age-standardized incidence and mortality rates of oral and pharyngeal cancer in Puerto Rico and among Non-Hispanics Whites, Non-Hispanic Blacks, and Hispanics in the USA

<p>Abstract</p> <p>Background</p> <p>In the American region, Puerto Rico (PR) has the highest incidence of oral and pharyngeal cancer (OPC), but racial/ethnic differences have never been assessed and compared with other groups in the United States of America (USA). We compared the age-adjusted incidence and mortality rates of OPC between PR and among USA Hispanics (USH), Non-Hispanic Whites (NHW), and Non-Hispanic Blacks (NHB) to assess the burden of this cancer in PR.</p> <p>Methods</p> <p>Analysis of the age-standardized rates (per 100,000) was performed using the direct method with the world standard population (ASR(World)) from 1998–2002. Annual percent change (APC) and Relative Risks (RR) were calculated using the Poisson regression model.</p> <p>Results</p> <p>The incidence ASR(World) for men in PR was constant (APC ≈ 0.0%), in contrast, a decrease was observed among NHW, NHB, and USH men, although only USH showed statistical significance (APC = -4.9%, p < 0.05). In women, the highest increase in incidence (APC = 5.3%) and the lowest decrease in mortality (APC = -1.4%) was observed in PR. The ratio of the ASR(World) showed that in all racial/ethnic groups, men had approximately 2–4 fold increased incidence and mortality risk of OPC than women (p < 0.05). Men in PR had a higher mortality risk (p < 0.05) of OPC as compared to USH, NHW, and NHB; but among women, PR showed a significant excess of mortality only as compared to USH (est. SRR = 1.82, 95% CI = 1.41, 2.33).</p> <p>Conclusion</p> <p>The overall higher incidence of OPC in men in PR as compared to USH, NHB, and NHW could be explained by the effect of gene-environment interactions. Meanwhile, the higher mortality from OPC in PR suggests limitations in the health-care access within this population. Further research is warranted to elucidate these findings.</p

Guía Mexicana de Práctica Clínica de Inmunoterapia 2011

Existen varias guías internacionales para la práctica clínica de in- munoterapia, que aplican solo parcialmente en México. La primera guía mexicana de inmunoterapia data de 1998

Treatment with tocilizumab or corticosteroids for COVID-19 patients with hyperinflammatory state: a multicentre cohort study (SAM-COVID-19)

Objectives: The objective of this study was to estimate the association between tocilizumab or corticosteroids and the risk of intubation or death in patients with coronavirus disease 19 (COVID-19) with a hyperinflammatory state according to clinical and laboratory parameters. Methods: A cohort study was performed in 60 Spanish hospitals including 778 patients with COVID-19 and clinical and laboratory data indicative of a hyperinflammatory state. Treatment was mainly with tocilizumab, an intermediate-high dose of corticosteroids (IHDC), a pulse dose of corticosteroids (PDC), combination therapy, or no treatment. Primary outcome was intubation or death; follow-up was 21 days. Propensity score-adjusted estimations using Cox regression (logistic regression if needed) were calculated. Propensity scores were used as confounders, matching variables and for the inverse probability of treatment weights (IPTWs). Results: In all, 88, 117, 78 and 151 patients treated with tocilizumab, IHDC, PDC, and combination therapy, respectively, were compared with 344 untreated patients. The primary endpoint occurred in 10 (11.4%), 27 (23.1%), 12 (15.4%), 40 (25.6%) and 69 (21.1%), respectively. The IPTW-based hazard ratios (odds ratio for combination therapy) for the primary endpoint were 0.32 (95%CI 0.22-0.47; p < 0.001) for tocilizumab, 0.82 (0.71-1.30; p 0.82) for IHDC, 0.61 (0.43-0.86; p 0.006) for PDC, and 1.17 (0.86-1.58; p 0.30) for combination therapy. Other applications of the propensity score provided similar results, but were not significant for PDC. Tocilizumab was also associated with lower hazard of death alone in IPTW analysis (0.07; 0.02-0.17; p < 0.001). Conclusions: Tocilizumab might be useful in COVID-19 patients with a hyperinflammatory state and should be prioritized for randomized trials in this situatio