Estados localizados y cadenas fermiónicas con defecto

En este trabajo se realiza el estudio de un modelo de aislante topológico unidimensional descrito por un hamiltonino cuadrático de fermiones sin espín con acoplos de alcance finito cuyos extremos se conectan mediante el denominado defecto de la cadena. Se realiza una breve contextualización del origen del modelo en el marco de los modelos tight-binding y se definen las simetrías discretas de la cadena. Posteriormente, se presenta la resolución de los autoestados del hamiltoniano mediante el formalismo de los modos de Bogoliubov y se construyen los invariantes topológicos del sistema. Finalmente, se estudia numéricamente la dependencia con el defecto del espectro energético y los estados localizados con un caso concreto.<br /

Implementación en el H.C.U. Lozano Blesa de una técnica de rutina para la verificación de la constancia de dosis en aplicadores Leipzig usando una cámara pozo

En este trabajo se implementa una técnica de rutina para realizar la verificación posicional clínica que permita garantizar la constancia de dosis en los tratamientos de braquiterapia superficial con aplicadores Leipzig tipo V en el Hospital Clínico Universitario Lozano Blesa. Se obtienen los valores de referencia y sus tolerancias con los que comparar las medidas de las verificaciones rutinarias. Se caracterizan la isotropía, repetibilidad, reproducibilidad y sensibilidad de la técnica implementada con el inserto plástico diseñado y con la plantilla confeccionada como alternativa más accesible al inserto.<br /

Aplicación de la realidad virtual para la capacitación en materia de comunicación en crisis sanitarias

Este proyecto trata el desarrollo de una aplicación de Realidad Virtual para formar a los portavoces sanitarios sobre cómo realizar una correcta comunicación durante una crisis sanitaria. Este tipo de comunicación posee características particulares que demandan conocimientos específicos y generan un impacto significativo en la sociedad, lo cual las distingue de otros tipos de comunicaciones. La aplicación consta de una parte formativa y otra parte de entrenamiento. En la parte formativa, el usuario recibe la información de un formador virtual y podrá elegir sobre qué temas quiere obtener información interactuando con su voz. Los módulos formativos aprovechan las virtudes de la realidad virtual enriqueciendo la experiencia con estímulos visuales de madera inmersiva. Por otro lado, en la parte de entrenamiento el usuario puede practicar como realizar una comunicación en una sala de prensa virtual, Y al finalizar recibirá un feedback con resultados e indicaciones para mejorar

Attitude control research with educational nanosatellites

This paper introduces the three-axis attitude control of the ESAT platform. ESAT is a modular nanosatellite that implements the popular 10x10x10 cm CubeSat standard, designed for hands-on learning at different educational levels as well as professional training. ESAT features the full set of characteristic spacecraft subsystems (power, on-board data handling, attitude control, communications, and payload). The satellite can be disassembled to focus on each subsystem, one at a time, or used all together, and features a flexible ground segment. Courses using the ESAT platform are imparted in our university, as part of the last year of the master’s degree in Aerospace engineering, and in other institutions like the ESA Academy. They cover aspects ranging from subsystems design to testing and spacecraft operations. In addition, the platform is used in master’s thesis and research activities. Although the version that is currently being used in the courses allows only one-axis attitude control, the ESAT is in continuous development and two prototypes of the satellite have already been developed that allow three-axis control based on reaction wheels and/or magnetorquers, which is essential for the testing and verification of attitude determination and control algorithms. For this purpose, the ground support equipment has also been updated to be able to carry out the turns in three axes, with the development of new testbeds and a complete magnetic field simulator. The present work aims to show the new three-axis platform designs and its main functionalitie

Searching for WIMPs with TREX-DM: achievements and challenges

The TREX-DM detector, a low background chamber with microbulk Micromegas readout, was commissioned in the underground laboratory of Canfranc (LSC) in 2018. Since then, data taking campaigns have been carried out with Argon and Neon mixtures, at different pressures from 1 to 4 bar. By achieving a low energy threshold of 1 keV$_{ee}$ and a background level of 80 counts keV$^{-1}$ Kg$^{-1}$ day$^{-1}$ in the region from 1 to 7 keV$_{ee}$, the experiment demonstrates its potential to search for low-mass WIMPs. Two of the most important challenges currently faced are the reduction of both, background level and energy threshold. With respect to the energy threshold, recently a new readout plane is being developed, based on the combination of Micromegas and GEM technologies, aiming to have a pre-amplification stage that would permit very low energy thresholds, close to the single-electron ionization energy. With respect to the background reduction, apart from studies to identify and minimize contamination population, a high sensitivity alpha detector is being developed in order to allow a proper material selection for the TREX-DM detector components. Both challenges, together with the optimization of the gas mixture used as target for the WIMP detection, will take TREX-DM to explore regions of WIMP's mass below 1 GeV c$^{-2}$.Comment: LIDINE 2023: LIght Detection In Noble Element

In your phase: neural phase synchronisation underlies visual imagery of faces

Abstract: Mental imagery is the process through which we retrieve and recombine information from our memory to elicit the subjective impression of “seeing with the mind’s eye”. In the social domain, we imagine other individuals while recalling our encounters with them or modelling alternative social interactions in future. Many studies using imaging and neurophysiological techniques have shown several similarities in brain activity between visual imagery and visual perception, and have identified frontoparietal, occipital and temporal neural components of visual imagery. However, the neural connectivity between these regions during visual imagery of socially relevant stimuli has not been studied. Here we used electroencephalography to investigate neural connectivity and its dynamics between frontal, parietal, occipital and temporal electrodes during visual imagery of faces. We found that voluntary visual imagery of faces is associated with long-range phase synchronisation in the gamma frequency range between frontoparietal electrode pairs and between occipitoparietal electrode pairs. In contrast, no effect of imagery was observed in the connectivity between occipitotemporal electrode pairs. Gamma range synchronisation between occipitoparietal electrode pairs predicted subjective ratings of the contour definition of imagined faces. Furthermore, we found that visual imagery of faces is associated with an increase of short-range frontal synchronisation in the theta frequency range, which temporally preceded the long-range increase in the gamma synchronisation. We speculate that the local frontal synchrony in the theta frequency range might be associated with an effortful top-down mnemonic reactivation of faces. In contrast, the long-range connectivity in the gamma frequency range along the fronto-parieto-occipital axis might be related to the endogenous binding and subjective clarity of facial visual features

Changes in rumen bacterial communities from cattle receiving immature oak (Quercus pyrenaica) leaves determined by fluorescence in situ hybridization and real-time PCR

Contributed to: 6th INRA-RRI Symposium. Gut Microbiome: Functionality, interaction with the host and impact on the environment (Clermont-Ferrand, Francia, Jun 18-20, 2008).In the hill areas of northern Spain intoxication of beef cattle occur recurrently in the spring when the animals graze in Pyrenean oak (Quercus pyrenaica) areas and consume immature oak leaves (OL). These leaves are rich in hydrolyzable tannins that are inhibitory to the growth and activity of many rumen microorganisms and may cause poisoning in animals if sufficiently large amounts are consumed. The aim of the study was to investigate the impact of the administration of hydrolyzable tannin-rich oak leaves on the rumen bacterial communities in cattle. Three ruminally cannulated Brown Swiss bulls were fed grass hay for an adaptation period before a progressive feed restriction 10-day period. Afterwards, they were offered daily 14 g dry matter (DM) of grass hay/kg metabolic weight (LW0.75), and 14 g DM of OL/kg LW 0.75 were administered through the cannula for 6 days. Then, all bulls received again grass hay. In situ determinations of OL and alfalfa hay (AH) degradation by rumen microbes and rumen samplings for microbial population studies (real time PCR - total rumen contents - and fluorescence in situ hybridization, FISH - rumen fluid -) were performed before and after the feed restriction, after 5 days of OL administration, and 4 days after stopping the administration. Inter-individual differences in bacterial profile were observed initially. Proportions of Gram-positive bacteria, Prevotella-Bacteroides, and other bacterial groups relative to total Eubacterial count (GP:Bac:Others) in the rumen fluid were 28:16:56 in animal 1, 30:9:61 in animal 2, and 27:6:67 in animal 3. The effect of feed restriction and OL administration on the studied microbial groups was similar in the three animals. Total eubacterial counts (Eub) were reduced by the feed restriction, but members of Bac and Streptococcus groups (by FISH) maintained or even increased their numbers. After 5 days of OL administration, Eub were recovered, the numbers of Streptococci were reduced and those of Bac did not change, whereas GP were stimulated, specially in bulls 2 and 3 (over 3-fold increase). These animals showed signs of intoxication and a lower microbial degradation of OL and AH in the rumen, did not ingest any hay and presented a 3-fold higher abundance of Streptococci in the rumen fluid after the OL administration than bull 1. On the contrary, the latter animal consumed all the offered hay and showed lower proportions of the Streptococcus bovis group relative to total eubacteria in total rumen contents (by real time PCR: 0.03 vs 1.13 and 0.99 %) than the intoxicated animals. Four days after stopping the OL administration, proportions of GP: Bac:Others were again different not only between animals but also from the initial values: 35:37:28 in animal 1, 20:58:22 in animal 2, and 17:19:64 in animal 3. The administration of tannin-rich oak leaves affected the composition of the bacterial population in the rumen, but their effects depended probably on the individual microbial profile. Further research is necessary to understand the role of the ruminal microbiota to prevent intoxications in cattle unadapted to the intake of tannin-rich plants.Peer reviewe

Preliminary study of the changes in rumen bacterial populations from cattle intoxicated with young oak (Quercus pyrenaica) leaves

7 pages, 3 tables, 4 figures.Intoxication of grazing cattle occurs repeatedly when they consume large amounts of young oak leaves (OL), that are rich in hydrolysable tannins (HT), due to a shortage of other feed resources. The HT are antimicrobial, although some rumen bacteria can resist or degrade them into potentially toxic or harmless metabolites. To study the effect of the administration of HT-rich OL (Quercus pyrenaica) after a severe feed restriction on the rumen bacterial community and monitor the variations in some bacterial groups that are potentially able to resist or metabolize tannins, 3 ruminally cannulated bulls were initially fed grass hay and then subjected to a severe 8-day feed restriction period, before receiving OL for 6 days. Then, the animals were offered again grass hay for 12 more days. Rumen contents were sampled throughout the experiment. Quantitative real-time PCR and terminal restriction fragment length polymorphism (T-RFLP) were used to monitor the bacterial dynamics. Animal 1 was not intoxicated and showed lower relative abundances of Streptococcus bovis initially and after the OL administration than animals 2 and 3, which showed acute signs of intoxication. The genus Prevotella increased its abundance with the OL administration, whereas Selenomonas ruminantium was reduced. The bacterial T-RFLP profile of animal 1 clustered initially separately from the animals 2 and 3 and was less affected by the feed restriction period. These results showed that the effect of the consumption of HT-rich OL after a severe feed restriction is highly variable in cattle and might rely on the individual composition of the microbiota colonizing the rumen.This work was supported by the Ministry of Education and Science (MEC, project AGL2004-06076-C02-01). P. G. Toral gratefully acknowledges receipt of a predoctoral grant from the Spanish National Research Council (CSIC, I3P Programme).Peer reviewe