Sub-Wavelength Profile 2-D Leaky-Wave Antennas With Two Periodic Layers

A fast and accurate analysis and synthesis technique for high-gain sub-wavelength 2-D Fabry-Perot leaky-wave antennas (LWA) consisting of two periodic metallodielectric arrays over a ground plane is presented. Full-wave method of moments (MoM) together with reciprocity is employed for the estimation of the near fields upon plane wave illumination and the extraction of the radiation patterns of the LWA. This yields a fast and rigorous tool for the characterisation of this type of antennas. A thorough convergence study for different antenna designs is presented and the operation principles of these antennas as well as the radiation characteristics are discussed. Moreover, design guidelines to tailor the antenna profile, the dimensions of the arrays as well as the antenna directivity and bandwidth are provided. A study on the radiation efficiency for antennas with different profiles is also presented and the trade off between directivity and radiation bandwidth is discussed. Numerical examples are given throughout to demonstrate the technique. A finite size antenna model is simulated using commercial software (CST Microstripes 2009) which validates the technique.

Power Stored and Quality Factors in Frequency Selective Surfaces at THz Frequencies

A study of the external, loaded and unloaded quality factors for frequency selective surfaces (FSSs) is presented. The study is focused on THz frequencies between 5 and 30 THz, where ohmic losses arising from the conductors become important. The influence of material properties, such as metal thickness, conductivity dispersion and surface roughness, is investigated. An equivalent circuit that models the FSS in the presence of ohmic losses is introduced and validated by means of full-wave results. Using both full-wave methods as well as a circuit model, the reactive energy stored in the vicinity of the FSS at resonance upon plane-wave incidence is presented. By studying a doubly periodic array of aluminium strips, it is revealed that the reactive power stored at resonance increases rapidly with increasing periodicity. Moreover, it is demonstrated that arrays with larger periodicity-and therefore less metallisation per unit area-exhibit stronger thermal absorption. Despite this absorption, arrays with higher periodicities produce higher unloaded quality factors. Finally, experimental results of a fabricated prototype operating at 14 THz are presented.

Near-field enhancement for infrared sensor applications

A detailed investigation on planar two dimensional metallodielectric dipole arrays with enhanced near-fields for sensing applications was carried out. Two approaches for enhancing the near-fields and increasing the quality factor were studied. The reactive power stored in the vicinity of the array at resonance increases rapidly with increasing periodicity. Higher quality factors are produced as a result. The excitation of the odd mode in the presence of a perturbation gives rise to a sharp resonance with near-field enhanced by at least an order of magnitude compared to unperturbed arrays. The trade-off between near-field enhancement and thermal losses was also studied, and the effect of supporting dielectric layers on thermal losses and quality factors were examined. Secondary transmissions due to the dielectric alone were found to enhance and reduce cyclically the quality factor as a function of the thickness of the dielectric material. The performance of a perturbed frequency selective surface in sensing nearby materials was investigated. Finally, unperturbed and perturbed arrays working at infrared frequencies were demonstrated experimentally. (C) 2011 Society of Photo-Optical Instrumentation Engineers (SPIE). [DOI: 10.1117/1.3604785]

Genome Expression Profiling-Based Identification and Administration Efficacy of Host-Directed Antimicrobial Drugs against Respiratory Infection by Nontypeable Haemophilus influenzae

Therapies that are safe, effective, and not vulnerable to developing resistance are highly desirable to counteract bacterial infections. Host-directed therapeutics is an antimicrobial approach alternative to conventional antibiotics based on perturbing host pathways subverted by pathogens during their life cycle by using host-directed drugs. In this study, we identified and evaluated the efficacy of a panel of host-directed drugs against respiratory infection by nontypeable Haemophilus influenzae (NTHi). NTHi is an opportunistic pathogen that is an important cause of exacerbation of chronic obstructive pulmonary disease (COPD). We screened for host genes differentially expressed upon infection by the clinical isolate NTHi375 by analyzing cell whole-genome expression profiling and identified a repertoire of host target candidates that were pharmacologically modulated. Based on the proposed relationship between NTHi intracellular location and persistence, we hypothesized that drugs perturbing host pathways used by NTHi to enter epithelial cells could have antimicrobial potential against NTHi infection. Interfering drugs were tested for their effects on bacterial and cellular viability, on NTHi-epithelial cell interplay, and on mouse pulmonary infection. Glucocorticoids and statins lacked in vitro and/or in vivo efficacy. Conversely, the sirtuin-1 activator resveratrol showed a bactericidal effect against NTHi, and the PDE4 inhibitor rolipram showed therapeutic efficacy by lowering NTHi375 counts intracellularly and in the lungs of infected mice. PDE4 inhibition is currently prescribed in COPD, and resveratrol is an attractive geroprotector for COPD treatment. Together, these results expand our knowledge of NTHi-triggered host subversion and frame the antimicrobial potential of rolipram and resveratrol against NTHi respiratory infection.

Aportaciones de un estudio etnográfico sobre la participación de las familias a la formación crítica del profesorado en una escuela inclusiva

El artículo que se presenta enfatiza la importancia de la formación crítica del profesorado para una escuela inclusiva a través de la investigación etnográfica. Más específicamente, el objetivo es dar a conocer y explicar cuáles son las aportaciones que percibe el profesorado cuando participa en una investigación etnográfica sobre las relaciones familia-escuela. El estudio se lleva a cabo desde la observación participante, entrevistas semi-estructuradas, análisis de documentos e interacción virtual en ocho escuelas de la Comunidad Autónoma de Aragón (España). Los resultados muestran cómo los profesores se hacen conscientes de sus prácticas y de su fundamentación teórica en relación con el contexto con el que interactúan. Los procesos de reflexión y el contraste con diferentes formas de acción parecen contribuir al cuestionamiento y a la reconstrucción de sus prácticas. El estudio destaca la importancia de los procesos de interacción que se generan durante la investigación etnográfica y más específicamente a través de la devolución de los informes de investigación para la formación de profesorado.

Comportamentos agressivos entre pares e padrões de vinculação: um estudo com jovens adolescentes

O presente estudo, desenvolvido com 237 jovens de três escolas do distrito de Évora, teve como objetivos caracterizar e analisar os comportamentos relacionados com situações de bullying (vitimação, do agressão e observação); e analisar a existência de eventuais relações entre padrões de vinculação e comportamentos agressivos entre pares. Utilizaram-se dois questionários de auto-relato, nomeadamente o QEVE – Questionário de Exclusão Social e Violência Escolar (Martins, 2003), que mede os comportamentos de agressão, vitimação e observação; e o IVIA – Inventário sobre Vinculação para a Infância e a Adolescência (Carvalho, Soares & Baptista, 2006), que analisa um conjunto de comportamentos e representações da vinculação na infância e na adolescência. Ambos os instrumentos mostraram boas qualidades psicométricas. Os resultados mostraram uma clara prevalência de situações de observação, relativamente às situações de agressão e de vitimação. Em todas estas situações, os comportamentos relacionados com a Exclusão Social e Agressão Verbal são os mais frequentes, comparativamente aos comportamentos relacionados com a Agressão Física. Os rapazes apresentaram médias mais elevadas em todas as escalas; os estudantes com menor percepção de suporte social na escola eram os que evidenciavam mais comportamentos de vitimação. No que se refere aos padrões de vinculação, os resultados mostraram que a vinculação segura parece funcionar como um fator protetor para a vitimação e para a agressividade. A partir dos resultados obtidos, serão analisadas pistas para uma intervenção psicoeducativa.

Progesterone actions in protein phosphorylation in the central nervous system

O presente trabalho propõe-se esclarecer o papel que a progesterona e os seus metabolitos exercem no sistema nervoso central. Nos últimos anos, com a descoberta da síntese local de esteróides no cérebro, a progesterona, assim como outras hormonas sexuais, ganharam uma relevância crescente em fenómenos tais como plasticidade neuronal e neuroprotecção. Ainda que já se comece a entender o papel de muitas hormonas no cérebro, tal como o estrogénio, o papel da progesterona continua menos conhecido. Deste modo, o nosso trabalho centrou-se na elucidação dos efeitos da progesterona em fenómenos de sobrevivência celular, plasticidade neuronal/sináptica. Graças à colaboração com um grupo pioneiro em estudos sobre hormonas sexuais neuroactivas, o presente trabalho fornece uma importante contribuição ao entendimento do papel desta hormona no sistema nervoso central. Este trabalho fornece novos dados, relativamente ao papel da progesterona e dos seus metabolitos reduzidos na regulação de vias de sinalização associadas com sobrevivência celular, tal como Akt/PI3K e ERK. Também é analisado o efeito do tratamento hormonal na expressão e estado de fosforilação da proteína Tau, sendo ainda motivo de estudo cinases e fosfatases envolvidas nestes mecanismos.