Thermoelectric spin voltage in graphene

In recent years, new spin-dependent thermal effects have been discovered in ferromagnets, stimulating a growing interest in spin caloritronics, a field that exploits the interaction between spin and heat currents. Amongst the most intriguing phenomena is the spin Seebeck effect, in which a thermal gradient gives rise to spin currents that are detected through the inverse spin Hall effect. Non-magnetic materials such as graphene are also relevant for spin caloritronics, thanks to efficient spin transport, energy-dependent carrier mobility and unique density of states. Here, we propose and demonstrate that a carrier thermal gradient in a graphene lateral spin valve can lead to a large increase of the spin voltage near to the graphene charge neutrality point. Such an increase results from a thermoelectric spin voltage, which is analogous to the voltage in a thermocouple and that can be enhanced by the presence of hot carriers generated by an applied current. These results could prove crucial to drive graphene spintronic devices and, in particular, to sustain pure spin signals with thermal gradients and to tune the remote spin accumulation by varying the spin-injection bias

Entanglement entropy of two disjoint blocks in XY chains

We study the Renyi entanglement entropies of two disjoint intervals in XY chains. We exploit the exact solution of the model in terms of free Majorana fermions and we show how to construct the reduced density matrix in the spin variables by taking properly into account the Jordan-Wigner string between the two blocks. From this we can evaluate any Renyi entropy of finite integer order. We study in details critical XX and Ising chains and we show that the asymptotic results for large blocks agree with recent conformal field theory predictions if corrections to the scaling are included in the analysis correctly. We also report results in the gapped phase and after a quantum quench.Comment: 34 pages, 11 figure

Interplay of superconductivity and magnetism in strong coupling

A model is introduced describing the interplay between superconductivity and spin-ordering. It is characterized by on-site repulsive electron-electron interactions, causing antiferromagnetism, and nearest-neighbor attractive interactions, giving rise to d-wave superconductivity. Due to a special choice for the lattice, this model has a strong-coupling limit where the superconductivity can be described by a bosonic theory, similar to the strongly coupled negative U Hubbard model. This limit is analyzed in the present paper. A rich mean-field phase diagram is found and the leading quantum corrections to the mean-field results are calculated. The first-order line between the antiferromagnetic- and the superconducting phase is found to terminate at a tricritical point, where two second-order lines originate. At these lines, the system undergoes a transition to- and from a phase exhibiting both antiferromagnetic order and superconductivity. At finite temperatures above the spin-disordering line, quantum-critical behavior is found. For specific values of the model parameters, it is possible to obtain SO(5) symmetry involving the spin- and the phase-sector at the tricritical point. Although this symmetry is explicitly broken by the projection to the lower Hubbard band, it survives on the mean-field level, and modes related to a spontaneously broken SO(5) symmetry are present on the level of the random phase approximation in the superconducting phase.Comment: 16 pages Revtex, 5 figure

A survey of zoonotic pathogens carried by house mouse and black rat populations in Yucatan, Mexico

The house mouse (Mus musculus) and the black rat (Rattus rattus) are reservoir hosts for zoonotic pathogens, several of which cause neglected tropical diseases (NTDs). Studies of the prevalence of these NTD-causing zoonotic pathogens, in house mice and black rats from tropical residential areas are scarce. Three hundred and two house mice and 161 black rats were trapped in 2013 from two urban neighbourhoods and a rural village in Yucatan, Mexico, and subsequently tested for Trypanosoma cruzi, Hymenolepis diminuta and Leptospira interrogans. Using the polymerase chain reaction we detected T. cruzi DNA in the hearts of 4.9% (8/165) and 6.2% (7/113) of house mice and black rats, respectively. We applied the sedimentation technique to detect eggs of H. diminuta in 0.5% (1/182) and 14.2% (15/106) of house mice and black rats, respectively. Through the immunofluorescent imprint method, L. interrogans was identified in 0.9% (1/106) of rat kidney impressions. Our results suggest that the black rat could be an important reservoir for T. cruzi and H. diminuta in the studied sites. Further studies examining seasonal and geographical patterns could increase our knowledge on the epidemiology of these pathogens in Mexico and the risk to public health posed by rodents.Centro de Estudios Parasitológicos y de Vectore

Reflexiones universitarias. San Pedro Valencia: renovación urbana, saneamiento ambiental y emprendimientos turísticos. Otoño 2015

Los trabajos que aquí se presentan se elaboraron por las y los estudiantes como parte de las actividades del Proyecto de Aplicación Profesional (PAP) “San Pedro Valencia: renovación urbana, saneamiento ambiental y emprendimientos turísticos”, durante el periodo de Otoño de 2015. A lo largo del periodo los autores compartieron sus reflexiones en torno a su percepción sobre el contexto en el que actúa el PAP; sobre las alternativas posibles a la problemática detectada y lo que significa pensar una alternativa; sobre los sujetos con los que se ha interactuado a lo largo de la experiencia de trabajo y sobre el papel del profesionista y del ciudadano en un mundo como el que nos tocó vivir. La obra está compuesta por reflexiones personales de las y los estudiantes que, explorando estas temáticas, comparten sus aprendizajes y observaciones de forma vívida.ITESO, A.C

Plan de trabajo y cronograma para la ejecución de actividades

Propuesta técnica que incluye el desarrollo de seis actividades que comprometen la entrega de resultados a través de siete productos principales. Las actividades entorno al cumplimiento del convenio son i) Construir la línea base de información secundaria disponible sobre biodiversidad para la cuenca del río Claro, Antioquia, que incluya, entre otros, datos sobre ecología, genética, uso, conservación, distribución, uso de hábitat, impactos e información espacial, procesos ecológicos; ii) Desarrollar un taller con actores clave en la gestión de la biodiversidad en la cuenca del río Claro, para la validación y robustecimiento de la línea base de información, así como para la identificación de vacíos de información y priorización de especies de interés, ecosistemas y temáticas, con miras a la construcción de agendas de investigación a largo plazo; iii) Construir propuestas de diseño de muestreo de la biodiversidad a diferentes niveles: especies, poblaciones, comunidades, ecosistemas, paisaje, ajustadas a las características socioecológicas de la cuenca del río Claro, para el establecimiento de plataformas de monitoreo, que incluyan además el recurso hídrico de la cuenca del río Claro, la diversidad subterránea, epígea y asociada al ecosistema cárstico; iv) Realizar al menos dos pre-salidas a la cuenca del río Claro, para el reconocimiento de las ventanas o localidades de trabajo y ajuste de las propuestas de diseño de muestreo, así como para la definición de aspectos logísticos; v) Evaluar el estado del conocimiento sobre la ecología del Jaguar ( Panthera onca ) en la cuenca del río Claro y generar una propuesta de muestreo no invasivo para conocer el estado de la diversidad genética de la especie en la región; vi) Articular la red de actores y expertos en grandes felinos para la construcción colectiva de herramientas de gestión y conservación para el Jaguar (Panthera onca).Bogotá, ColombiaCiencias Básicas de la Biodiversida

Nociones generales de muestreo aplicadas a las ciencias de la salud

El artículo tiene por objetivo describir nociones generales demuestreo aplicadas a las ciencias en el área de la salud, analizandodefiniciones, fórmulas, procedimientos y datos. Enestudios probabilísticos, la población objeto de estudio estádeterminada por la muestra a través de un plan de muestreo.En un proceso estadístico son importantes las unidades primarias,secundarias y terciarias de muestreo. Igualmente, eltipo de muestreo puede ser aleatorio simple, sistemático estratificadoo por conglomerados. Los siguientes criterios requierenclaridad y fundamentación: tamaño de la población,nivel de confianza, error relativo, efecto del diseño, efecto deldiseño ajustado, parámetro de interés, varianza estimada ytasa de no respuesta, permitiendo disminuir costos y tiempo,además de inducir resultados y hallazgos desde la muestraen función de la población. Para analizar un estadístico oparámetro desde un resultado inferencial, se requiere de unexperto en matemáticas o estadística, con conocimiento entécnicas para recolectar, analizar e interpretar la información,razones que permiten al investigador una mayor validez yconfiabilidad de los resultados obtenidos de la investigación

Statistical Methods in Recent HIV Noninferiority Trials: Reanalysis of 11 Trials

Background: In recent years the ‘‘noninferiority’ ’ trial has emerged as the new standard design for HIV drug development among antiretroviral patients often with a primary endpoint based on the difference in success rates between the two treatment groups. Different statistical methods have been introduced to provide confidence intervals for that difference. The main objective is to investigate whether the choice of the statistical method changes the conclusion of the trials. Methods: We presented 11 trials published in 2010 using a difference in proportions as the primary endpoint. In these trials, 5 different statistical methods have been used to estimate such confidence intervals. The five methods are described and applied to data from the 11 trials. The noninferiority of the new treatment is not demonstrated if the prespecified noninferiority margin it includes in the confidence interval of the treatment difference. Results: Results indicated that confidence intervals can be quite different according to the method used. In many situations, however, conclusions of the trials are not altered because point estimates of the treatment difference were too far from the prespecified noninferiority margins. Nevertheless, in few trials the use of different statistical methods led to different conclusions. In particular the use of ‘‘exact’ ’ methods can be very confusing. Conclusion: Statistical methods used to estimate confidence intervals in noninferiority trials have a strong impact on th

Impact of biological agents on postsurgical complications in inflammatory bowel disease: A multicentre study of Geteccu

Background: The impact of biologics on the risk of postoperative complications (PC) in inflammatory bowel disease (IBD) is still an ongoing debate. This lack of evidence is more relevant for ustekinumab and vedolizumab. Aims: To evaluate the impact of biologics on the risk of PC. Methods: A retrospective study was performed in 37 centres. Patients treated with biologics within 12 weeks before surgery were considered “exposed”. The impact of the exposure on the risk of 30-day PC and the risk of infections was assessed by logistic regression and propensity score-matched analysis. Results: A total of 1535 surgeries were performed on 1370 patients. Of them, 711 surgeries were conducted in the exposed cohort (584 anti-TNF, 58 vedolizumab and 69 ustekinumab). In the multivariate analysis, male gender (OR: 1.5; 95% CI: 1.2–2.0), urgent surgery (OR: 1.6; 95% CI: 1.2–2.2), laparotomy approach (OR: 1.5; 95% CI: 1.1–1.9) and severe anaemia (OR: 1.8; 95% CI: 1.3–2.6) had higher risk of PC, while academic hospitals had significantly lower risk. Exposure to biologics (either anti-TNF, vedolizumab or ustekinumab) did not increase the risk of PC (OR: 1.2; 95% CI: 0.97–1.58), although it could be a risk factor for postoperative infections (OR 1.5; 95% CI: 1.03–2.27). Conclusions: Preoperative administration of biologics does not seem to be a risk factor for overall PC, although it may be so for postoperative infections