Design of a Ku-Band High-Purity Transducer for the TM01 Circular Waveguide Mode by Means of T-Type Junctions

© 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other worksA new mode transducer for converting the TE10 rectangular waveguide mode to the TM01 circular waveguide mode is presented. The novel topology is based on two T type junctions with in-phaseexcitation at their input rectangular ports. The first one is an H-plane T-junction in rectangular waveguide. The second one differs from the standard E-plane T-junction in the excitation, which is carried out by modes excited with fields having the same in-phase polarization at the input rectangular ports, and has the output port in circular waveguide. This configuration exploits the symmetry of the modes under consideration to achieve a high-purity conversion, controlling the propagating circular waveguide TE11 mode to a maximum level of -42 dB in the whole operation band. The design bandwidth is 2 GHz centered at 12 GHz with a return loss level higher than 28 dB. In addition, the transducer can be divided in a main body plus a cover for easing the manufacturing. In order to verify the proposed geometry, a back-to-back arrangement has been measured connecting two similar aluminum transducers with four different angles between their rectangular ports (0◦, 45◦, 90◦, and 180◦). The excellent experimental results validate the novel transducer with a measured converting efficiency higher than 98.2% in a 16.7% relative frequency bandwidthThis work was supported by the Spanish Government (Agencia Estatal de Investigación) under Grant (ADDMATE) TEC2016-76070-C3-1/2-R (AEI/FEDER/UE

Mechanically reconfigurable linear phased array antenna based on single-block waveguide reflective phase shifters with tuning screws

This work presents the design and prototyping of a reconfigurable phased array in Ku band (16 to 18 GHz) implemented in waveguide technology. The design is based on the use of a novel seamless waveguide module integrating four reconfigurable phase shifters to adjust the relative phase shift between the unitary elements of a linear array, which are illuminated uniformly by a corporate waveguide feeding network. The phase shifters are implemented by a 90º hybrid coupler in waveguide technology where two of its ports are loaded with a tunable reactive load, implemented in this proof of concept with a tuning screw. The four phase shifters have been manufactured in a single part using direct metal laser sintering, avoiding the losses related to bad electric contacts and misalignments associated to multipart devices. This also simplifies the assembly of the full phased array, leading to a modular approach with three parts whose design can be addressed separately. The experimental results for the complete array antenna show great performance and demonstrate that the main-lobe of the radiation pattern can be effectively scanned continuously between the angles - 25º and 25º, with a high efficiency in the whole design band thanks to the proposed waveguide implementationThis work was supported by the Spanish Government, Agencia Estatal de Investigación, Fondo Europeo de Desarrollo Regional: AEI/FEDER, UE, under Grant TEC2016-76070-C3-1-

La potencialidad de la nube para el trabajo de campo en geografía: el Parque Nacional de la Sierra de Guadarrama

Depto. de Didáctica de las Ciencias Experimentales , Sociales y MatemáticasFac. de EducaciónFALSEsubmitte

Especificación de un modelo para el estudio de la percepción de utilidad

A model is a data management, production and transfer system organized in explanatory trends of past, current and future relationships. The emphasis on each suggests decision making and strategy execution. The objective of this work was to specify a model for of the perception of utility. An exploratory and cross-sectional study was conducted with a selection of 186 students from a public university in central Mexico, considering their participation in the system of professional practices and social service in local organizations. The validity of the instrument that found a one-dimensional variable that explained 43% of the variance was established, but the research design limited the results to the research scenario, suggesting the extension of the work

S-Adenosylmethionine revisited: its essential role in the regulation of liver function

Dietary methionine is mainly metabolized in the liver where it is converted into S-adenosylmethionine (AdoMet), the main biologic methyl donor. This reaction is catalyzed by methionine adenosyltransferase I/III (MAT I/III), the product of MAT1A gene, which is exclusively expressed in this organ. It was first observed that serum methionine levels were elevated in experimental models of liver damage and in liver cirrhosis in human beings. Results of further studies showed that this pathological alteration was due to reduced MAT1A gene expression and MAT I/III enzyme inactivation associated with liver injury. Synthesis of AdoMet is essential to all cells in the organism, but it is in the liver where most of the methylation reactions take place. The central role played by AdoMet in cellular function, together with the observation that AdoMet administration reduces liver damage caused by different agents and improves survival of alcohol-dependent patients with cirrhosis, led us to propose that alterations in methionine metabolism could play a role in the onset of liver disease and not just be a consequence of it. In the present work, we review the recent findings that support this hypothesis and highlight the mechanisms behind the hepatoprotective role of AdoMet

Regulation of mammalian liver methionine adenosyltransferase

S-adenosylmethionine (SAM) is an essential metabolite in all cells. SAM is the most important biological methyl group donor and is a precursor in the synthesis of polyamines. Methionine adenosyltransferase (MAT; EC 2.5.1.6) catalyzes the only known SAM biosynthetic reaction from methionine and ATP. In mammalian tissues, three different forms of MAT (MAT I, MAT III and MAT II) have been identified that are the product of two different genes (MAT1A and MAT2A). Although MAT2A is expressed in all mammalian tissues, the expression of MAT1A is primarily restricted to adult liver. In mammals, up to 85% of all methylation reactions and as much as 48% of methionine metabolism occurs in the liver, which indicates the important role of this organ in the regulation of blood methionine. Recent evidence indicates that not only is SAM the main biological methyl group donor and an intermediate metabolite in methionine catabolism, but it is also an intracellular control switch that regulates essential hepatic functions such as liver regeneration and differentiation as well as the sensitivity of this organ to injury. Therefore, knowledge of factors that regulate the activity of MAT I/III, the specific liver enzyme, is essential to understand how cellular SAM levels are controlled

The confining-Higgs phase transition in U(1)-Higgs LGT

Abstract We simulate the compact U(1)-Higgs model in a four-dimensional lattice. We present a numerical study for the behaviour around the region where the transition between the confining and Higgs phases disappears. The transition line is found to be first order and to end in a second-order point. We measure the critical exponents of the endpoint obtaining the mean field ones within errors

Aplicación de las tecnologías de la información geográfica en el diseño de itinerarios para la educación en paisaje en el ámbito de los Parques Nacionales

El proyecto pretende acercar los distintos tipos de paisajes a los estudiantes a partir de un itinerario y realizar una explicación a través de diversas actividades, que estarán disponibles online, de forma que se puedan trabajar los parques tanto de forma virtual como real. Los medios con los que contamos se basan en el trabajo realizado en el PIMCD anterior (PIMCD 224/2015 La potencialidad de la nube para el trabajo de campo en Geografía: El Parque Nacional de la Sierra de Guadarrama), centrado sobre el PN Sierra de Guadarrama, cuya metodología y recursos pedagógicos empleados serán enriquecidos y reutilizados en este proyecto en el que se continuará empleando las tecnologías de la información geográfica para el diseño de itinerarios geográficos que pongan al alcance de los docentes los paisajes de los Parques Nacionales, en el primer centenario de la Ley que crea su figura (primera Ley de Parques Nacionales se promulga en 1916). Tomando como punto de partida el concepto de paisaje que acuerda el Convenio Europeo del Paisaje (CEP) y las premisas didácticas que el mismo expone relativas a la inscripción de los aprendizajes necesarios, somos conscientes de la multiplicidad de recursos de que hoy disponemos para contribuir positivamente a desarrollar la sensibilidad y el sentido ético de los estudiantes y el profesorado hacia los paisajes en general y los espacios naturales protegidos en particular. Multiplicidad que responde tanto a la creciente disponibilidad de recursos web e información geográfica que ofrece la nube, como a la accesibilidad a nuevos dispositivos como GPS, tabletas o smartphones, que han supuesto una generalización en el acceso a información georreferenciada. Partiendo de esta realidad, nuestro proyecto se vertebra en dos líneas preferentes. Por un lado, acercar esta diversidad de nuevas tecnologías y la información geográfica o geoinformación al profesorado y alumnado, ofreciendo recursos que sirvan para el aprendizaje de su manejo dentro y fuera del aula y, por otro, mejorar el conocimiento de los valores naturales y culturales de distintos espacios singulares y sus paisajes, fomentando una conciencia social conservacionista tal y como contempla entre sus objetivos principales la Red de Parques Nacionales de España