Simulación Monte Carlo del comportamiento ferroeléctrico de películas de PZT empleando un Hamiltoniano DIFFOUR dependiente de la presión

In this work the polarization and hysteresis response of Lead Zirconate Titanate (PZT) ferroelectric thin films was studied in relation to the variation on temperature, stress, electric field and the content of non-ferroelectric impurities by using a MontEn este trabajo, se estudió la respuesta de polarización e histéresis de las películas finas ferroeléctricas de titanato de zirconato de plomo (PZT) en relación con la variación de temperatura, tensión, campo eléctrico y el contenido de impurezas no ferr

GESTIÓN TURÍSTICA DEL PATRIMONIO CULTURAL: EL CASO DE ETNIA MATLATZINCA EN EL ESTADO DE MÉXICO

This paper describes the implementation of a tourism management strategy for endogenous resources in the village called San Francisco Oxtotilpan, in the state of Mexico. It is a Matlatzinca community that has natural resources framed in a vast cultural richness, which has been maintained through the preservation of customs and traditions. A case study was carried out, with a focus on the action research methodology, with the purpose of identifying participatory heritage management processes in the implementation of rural tourism strategies. The application of a collaborative program, in which the inhabitants of the community participate, gave legitimacy to the actions carried out.En la presente investigación se describe la aplicación de una estrategia de gestión turística de los recursos patrimoniales en el poblado de San Francisco Oxtotilpan, Estado de México. Se trata de una comunidad matlatzinca que cuenta con recursos naturales enmarcados en una vasta riqueza cultural, que se han mantenido a través de la preservación de sus costumbres y tradiciones. Se desarrolló un estudio de caso, con un enfoque centrado en la metodología de investigación–acción, con el objetivo de identificar los procesos de gestión patrimonial participativa en la implementación de estrategias de turismo rural. La aplicación de un programa colaborativo, protagonizado por los habitantes de la comunidad otorgó legitimidad a las acciones desarrolladas

Algunas soluciones exactas para una ecuación de Klein Gordon

In solving practical problems in science and engineering arises as a direct consequence differential equations that explains the dynamics of the phenomena. Finding exact solutions to this equations provides importan information about the behavior of physical systems. The Lie symmetry method allows tofind invariant solutions under certain groups of transformations for differential equations.This method not very well known and used is of great importance in the scientific community. By this approach it was possible to find several exactinvariant solutions for the Klein Gordon Equation uxx − utt = k(u). A particularcase, The Kolmogorov equation uxx − utt = k1u + k2un was considered.These equations appear in the study of relativistic and quantum physics. The general solutions found, could be used for future explorations on the study for other specific K(u) functions.Al resolver problemas prácticos en ciencia e ingeniería surge como consecuencia directa las ecuaciones diferenciales que explican la dinámica de los fenómenos. Encontrar soluciones exactas a estas ecuaciones proporciona información importante sobre el comportamiento de los sistemas físicos. El método de simetría de Lie permite encontrar soluciones invariantes bajo ciertos grupos de transformaciones para ecuaciones diferenciales. Este método, poco conocido y utilizado, es de gran importancia en la comunidad científica. Mediante este enfoque, fue posible encontrar varias soluciones exactas invariables para la ecuación de Klein Gordon uxx - utt = k (u). Un caso particular, se consideró la ecuación de Kolmogorov uxx - utt = k1u + k2un. Estas ecuaciones aparecen en el estudio de la física relativista y cuántica. Las soluciones generales encontradas podrían utilizarse para futuras exploraciones en el estudio para otras funciones específicas de K (u)

Propuestas para una reforma laboral democrática

Este trabajo, presenta trece propuestas complementarias sobre los temas centrales de la reforma laboral: la contracción individual y colectiva, con si variable de "subcontratación"; la transparencia con la proposición concreta de creación del registro nacional de contratos y sindicatos; los salarios y la jornada laboral, temas clave en el proyecto de país de la izquierda democrátic

Cu^II/Cu^I decorated N-doped carbonaceous electrocatalysts for the oxygen reduction reaction

The oxygen reduction reaction (ORR) that for instance takes place at the cathode of fuel cells is one of the most examined model reactions of energy conversion. The ORR presents sluggish reaction kinetics, thus limiting the overall efficiency of these cells. Pt-based catalysts are still the widest choice though they exhibit important drawbacks such as long-term instability and intolerance to methanol crossover. In this context, engineering transition metals in the form of nano- and subnano-sites on carbonaceous supports has the potential of becoming an alternative to scarce noble metal-based catalysts. Herein, we describe a simple synthetic route towards CuII/CuI decorated N-doped carbonaceous ORR electrocatalysts. CuII/CuI nanosites are obtained by calcination in air of an ionic liquid derived noble carbonaceous support impregnated with copper(ii) acetate. The strong interaction between the copper and the noble support foster the co-formation of CuII/CuI nanosites. Larger amounts of copper(ii) acetate translate into larger amounts of CuI and lower Tafel slopes. The material with 4 wt% of copper catalyzes the selective reduction of oxygen through a 4-electron transfer pathway and exhibits a lower Tafel slope than commercial platinum, a minimal overpotential, and a higher limiting current density. Moreover, all materials show promising durability and high methanol stability, which makes them promising to replace noble metals for the ORR

Background studies and shielding effects for the TPC detector of the CAST experiment

Sunset solar axions traversing the intense magnetic field of the CERN Axion Solar Telescope (CAST) experiment may be detected in a Time Projection Chamber (TPC) detector, as X-rays signals. These signals could be masked, however, by the inhomogeneous background of materials in the experimental site. A detailed analysis, based on the detector characteristics, the background radiation at the CAST site, simulations and experimental results, has allowed us to design a shielding which reduces the background level by a factor of ~4 compared to the detector without shielding, depending on its position, in the energy range between 1 and 10 keV. Moreover, this shielding has improved the homogeneity of background measured by the TPC.Comment: 14 pages, 5 figures, accepted in New Journal of Physic

Preliminary field screening of maize landrace germplasm from northeastern Mexico under high temperatures

Northeastern Mexico has a wide variety of maize landraces that have not been characterized, and landraces vari¬eties may be a good source of new allelic diversity for useful traits. This study evaluated 28 accessions from Tam¬aulipas, in Northeast Mexico, chosen by phenology and for agronomic characteristics to represent the diversity of germplasm in the collection and agro-ecosystems of this area. They were evaluated under high temperature in the field as a basis for an efficient use of this maize germplasm in a breeding program; in particular we investigated changes in agronomic characteristics affected by high temperatures in all growing seasons. Results indicated that in late planting dates air temperatures become excessively high during the flowering period and growing season; in these conditions a loss in grain yield can be sustained. In this study, the loss initially manifests itself as a reduc¬tion in grain yield (> 32%) because of fewer grains per ear (>26%). Landrace maize accessions C-3030, C-3049, C-3015, Pob. I, Pob. II, ZEM-148 and C-4050 were identified with high relative yield and yield components traits under high temperature conditions. These accessions have greater agronomic stability, and also are potential donors of genes to improve maize tolerance to high temperature

Transmembrane and truncated (SEC) isoforms of MUC1 in the human endometrium and Fallopian tube

The cell surface mucin MUC1 is expressed by endometrial epithelial cells with increased abundance in the secretory phase of the menstrual cycle, when it is found both at the apical cell surface and in secretions. This suggests the presence of a maternal cell surface glycoprotein barrier to embryo implantation, arising from the anti-adhesive property of MUC1. In previous work, we demonstrated alternatively spliced MUC1 variant forms in tumour cells. The variant MUC1/SEC lacks the transmembrane and cytoplasmic sequences found in the full-length variant. We now show that MUC1/SEC mRNA is present in endometrial carcinoma cell lines, endometrial tissue and primary cultured endometrial epithelial cells. The protein can be detected using isoform-specific antibodies in uterine flushings, suggesting release from endometrium in vivo. However, on the basis of immunolocalisation studies, MUC1/SEC also remains associated with the apical epithelial surface both in tissue and in cultured cells. Transmembrane MUC1 and MUC1/SEC are both strikingly localised to the apical surface of tubal epithelium. Thus MUC1 may contribute to the anti-adhesive character of the tubal surface, inhibiting ectopic implantation. The mechanism by which this barrier is overcome in endometrium at implantation is the subject of ongoing investigation

Alteraciones estructurales del tejido óseo en ratas tratadas con tetratiomolibdato de amonio

El tetratiomolibdato (TTMo) se sintetiza en los pre–estómagos de los rumiantes por reaccióndel molibdeno con los sulfuros producidos por reducción bacteriana de los elementosazufrados de la dieta. TTMo sería el responsable tanto del bloqueo de la absorción del cobrecomo de su posterior utilización tisular, provocando una deficiencia secundaria del mismo.El objetivo del trabajo fue verificar el efecto del TTMo de amonio sobre la histología dehuesos largos en este modelo experimental con el fin de aportar información acerca de la fragilidadósea que presentan los rumiantes con molibdenosis. Se utilizaron 30 ratas Wistar desexo macho, de 80 a 90 días de edad, agrupadas en forma aleatoria en lotes testigos y tratados,conformados con 15 animales cada uno. Estos últimos recibieron 54 mg/l de TTMo conel agua de bebida durante 100 días y, teniendo en cuenta el contenido de Cu y Mo de la dietay la cantidad de agua y alimento consumido, el lote tratado fue sometido a un desafío de 40ppm de Mo. Los animales mostraron sintomatología clínica claramente compatible con unadeficiencia secundaria de Cu por molibdenosis. Las lesiones más importantes observadas enel tejido óseo de los animales tratados consistieron en engrosamiento del cartílago de crecimiento,con masas de condrocitos hipertróficos y falta de distribución ordenada de células enforma columnar. El tejido subperióstico mostró un incremento de espesor y hemorragias entoda la extensión de diáfisis y metáfisis. También se observó falta de reemplazo del cartílagoy hueso inmaduro por tejido óseo maduro, acompañado por abundante producción de tejidofibroso, alterándose así la estructura ósea normal. Tales lesiones pudieron ser provocadaspor reacciones tisulares de expansión transversal metafisiaria por una mayor deformabilidadósea frente al desafío de cargas que el hueso debió soportar