A study of breakdown limits in microstrip gas counters with preamplification structures

We have studied the charge and breakdown limits of Microstrip Gas Counters (MSGC's) with two different preamplification structures: the Gas Electron Multiplier (GEM) and the Parallel-Plate Avalanche Counter (PPAC). It was found that in both cases the breakdown limit was increased by 1-2 orders of magnitude compared to the bare MSGC and that this was due to the spreading of the primary electron cloud during pre-amplification. This spreading reduces the charge density in the final MSGC avalanche, permitting much higher total gains before streamers form. The real practical gain limitations in these two-stage detectors arose not from sparking, but from a loss of proportionality due to space charge effects.http://www.sciencedirect.com/science/article/B6TJM-3V8TV5X-34/1/126083510ba3bfd528bad96ccdbc08a

Comparação dos efeitos secundários agudos da Radioterapia por intensidade modulada com a Radioterapia tridimensional conformada no carcinoma de próstata

Introdução: Este trabalho tem como principal objectivo comparar os efeitos secundários agudos da Radioterapia por Intensidade Modulada (IMRT) e a Radioterapia Tridimensional Conformada (3 D-CRT) no carcinoma de Próstata; Materiais e métodos: Foram observados os processos clínicos de 30 doentes e analisados os efeitos colaterais da RT ocorridos no decurso do tratamento. Resultados: A percentagem de toxicidade aguda dermatológica foi superior no grupo tratado com 3D-CRT. Nenhum doente apresentou toxicidade aguda grave. Conclusões: O tamanho reduzido da amostra e a ausência de valores estatisticamente significativos, não permite concluir a influência da técnica de RT no desenvolvimento de efeitos secundários agudos.Introduction: This study has as main objective to compare the acute side effects for Intensity Modulated Radiotherapy (IMRT) and Tridimensional Conformal Radiotherapy (3D-CRT) in prostate cancer; Materials and methods: We observed the clinical files of 30 patients and analyzed the side effects of RT occurred in the course of treatment. Results: The percentage of acute dermatological toxicity was higher in the group treated with 3D-CRT. No patient showed severe acute toxicity. Conclusions: The small sample size and lack of statistically significant values, does not suggest the influence of RT on the development of acute side effects

On the physics and technology of gaseous particle detectors

Despite an already long and fruitful history, gaseous elementary-particle detectors remain today an important mainstay of high-energy and nuclear physics experiments and of radiation detection in general. In here we briefly describe some of the gaseous detector's main technologies and applications, along with some unsolved gas-discharge physics aspects of practical relevance.Comment: Submitted to Plasma Sources in Science and Technolog

Instrumentation for X-Ray Astronomy from High-Altitude Balloons: Recent Developments and Future Plans

We describe our current effort and future plans to develop new detectors and methods for studying hard x-ray emission from the Universe during balloon flights

Breakdown Limit Studies in High Rate Gaseous Detectors

We report results from a systematic study of breakdown limits for novel high rate gaseous detectors: MICROMEGAS, CAT and GEM, together with more conventional devices such as thin-gap parallel-mesh chambers and high-rate wire chambers. It was found that for all these detectors, the maximum achievable gain, before breakdown appears, drops dramatically with incident flux, and is sometimes inversely proportional to it. Further, in the presence of alpha particles, typical of the backgrounds in high-energy experiments, additional gain drops of 1-2 orders of magnitude were observed for many detectors. It was found that breakdowns at high rates occur through what we have termed an "accumulative" mechanism, which does not seem to have been previously reported in the literature. Results of these studies may help in choosing the optimum detector for given experimental conditions

A platform to integrate crowdsourced, physical sensor and official geographic information to assist authorities in emergency response

In this work, a prototype GIS-based platform to integrate Volunteered Geographic Information from various sources with other spatial data is presented, aiming at assisting civil protection authorities in emergency response situations. The platform is now in the implementation phase, and this paper covers some aspects about its development and preliminary results to demonstrate the potentialities of the approach proposed

"RESPONSABILIDADE Social: uma Abordagem Crítica a Partir do Estudo de Caso em uma Empresa do Setor Farmacêutico de Vitória"

Atualmente, responsabilidade social é um assunto presente nos discursos de muitas empresas e nos estudos de teóricos da administração e de diversas áreas do conhecimento humano, como a Economia, a Filosofia e a Sciologia. Este trabalho traz um estudo panorâmico sobre o tema, começando por seus diferentes conceitos e justificativas de adoção, passando por uma narrativa sobre a extensão de débito que a empresa capitalista possui tanto com a sociedade quanto com o meio ambiente. Apresenta os principais debates que cercam o tema, os instrumentos utilizados pelas empresas para expressarem sua responsabilidade social, além de várias críticas que o próprio mercado faz aos modelos de gestão da responsabilidade social por ele mesmo criados. Realiza um estudo de caso em uma empresa de pequeno porte, reconhecida pela comunidade local da Região Metropolitana de Vitória como socialmente responsável. Tem como objetivo geral o desenvolvimento de uma avaliação crítica da responsabilidade social a partir da prática da empresa pesquisada e, mais especificamente, verificar quais as concepções de responsabilidade social vigentes, analisar se as práticas da organização pesquisada ratificam ou contradizem a teoria e, também, verificar quais os aspectos envolvidos na adoção de uma proposta de responsabilidade social pela empresa

Oxygen depletion in giant planets with different formation histories

The atmospheric C/O ratio of exoplanets is widely used to constrain their formation. To guarantee that the C/O ratio provides robust information, we need to accurately quantify the amount of C and O in exoplanetary atmospheres. In the case of O, water and carbon monoxide are generally studied as the two key carriers. However, oxygen is a very reactive element and does not bind with carbon; depending on the temperature, it also binds to refractory elements. Estimating the amount of oxygen bound to refractory elements is therefore critical for unbiased estimates of the C/O ratio. In this work, we investigate the oxygen deficit due to refractory elements and its effects on the atmospheric C/O ratio of giant exoplanets as a function of their metallicity and equilibrium temperature. We model the composition of planetary atmospheres assuming chemical equilibrium and using as input physically justified elemental mixtures arising from detailed planet formation simulations. Our results show how the interplay between the atmospheric temperature and non-solar abundances of oxygen and refractory elements can sequester large fractions of oxygen, introducing significant biases in evaluating the C/O ratio when this effect is not accounted for. We apply our results to the case of Jupiter in the Solar System and show how the currently estimated water abundance points to a true oxygen abundance that is four times the solar one