The effect of proton damage on the X-ray spectral response of MOS CCDs for the swift X-ray telescope

The effect of non-ionising energy loss(NIEL) of protons in charge-coupled devices is to displace silicon atoms and any dopant materials present from their lattice positions to form lattice defects which in turn can trap electrons [1]. A CCD operating as a photon counter for x-ray spectroscopy relies on the efficient transfer of charge from one region to another. The number of defects produced will reduce the charge transfer efficiency (CTE) and hence degrade the spectral resolution of the energy distribution of interest [2]. The Swift X-ray Telescope will be equipped with a single EPIC MOS CCD22 as developed for the XMM project [3]. It is the aim of this study to determine the effect of the radiation environment on the performance of the CCD and its impact on the scientific objective of the x-ray telescope, to probe the x-ray afterglow of Gamma Ray Bursts (GRBs)

Cerium neodymium oxide solid solution synthesis as a potential analogue for substoichiometric AmO 2 for radioisotope power systems

The European Space Agency (ESA) is sponsoring a research programme on the development of americium oxides for radioisotope generators and heater units. Cubic AmO2-(x/2) with an O/Am ratio between 1.65 and 1.75 is a potentially suitable compound for pellet sintering. C-type (Ia-3) Ce1-xNdxO2-(x/2) oxides with 0.5 &lt; x &lt; 0.7 could be used as a surrogate for some Ia-3 AmO2-(x/2). A new Ce1-xNdxO2-(x/2) production process has been investigated where a nominally selected x value of 0.6 was targeted: Ce and Nd nitrates and oxalic acid were added drop-wise into a vessel, where they continuously reacted to create oxalate precipitates. The effect of temperature (25 °C, 60 °C) of the reactants (mixed at 250 revolutions per minute) on oxalate particle shape and size were investigated. Oxalates were calcined at 900 °C to produce oxide particles. Oxalate particle properties were characterised as these are expected to influence oxides particle properties and fuel pellet sintering.</p

Dimensão econômica de sistemas de integração lavoura-pecuária

Os sistemas de integração lavoura-pecuária (ILP) têm sido propostos como solução tecnológica para atender critérios de sustentabilidade, mas tal assertiva tem-se baseado principalmente em indicadores agronômicos e ambientais. Neste trabalho, explorou-se a perspectiva econômica da ILP. Os benefícios econômicos potenciais desses sistemas podem refletir-se em economia de escopo (diminuição do custo, em razão da produção de múltiplos produtos) ou nos efeitos de redução de risco pela diversificação. Além disso, eles podem envolver menor variabilidade produtiva e maior produtividade. A mensuração acurada das interações entre os componentes lavoura e animal (pastagem) é etapa-chave a ser perseguida. A tomada de decisão em prol de sistemas diversificados vis-à-vis sistemas especializados deve ser feita de acordo com os preços relativos. A ILP compete com sistemas especializados de pecuária, mas não apresenta taxas de retorno competitivas em comparação a sistemas especializados com soja. A elevada demanda por capital da ILP, particularmente para a aquisição de animais em recria para a engorda, explica as menores taxas de retorno da ILP e é vista como uma das principais restrições para a ampla adoção de sistemas mistos. O desenho de mecanismos de financiamento inovadores será essencial para promover e acelerar a adoção em larga escala da tecnologia

Long-term results of treatment for craniopharyngioma in children

Results of the treatment of 27 children with craniopharyngioma are reported. A subfrontal pterional approach was used in 55.6% of cases, a transsphenoidal and a transcallosal or transcortical approach in 25.9% and 18.5% of cases, respectively. Radical removal was the goal of surgery and was achieved in 70.8% of cases treated as primary surgery. The operative mortality was 3.7% and was due to hypothalamic failure. Most (81.4%) patients were followed up, for a mean of 7 years. Patients were evaluated according to a functional evaluation scale and outcome categories proposed by us. The scale takes account of tumor (recurrences and their eventual evolution); visual functions; endocrine functions (mainly hypothalamic), attainment of endocrine balance and drug regimen; headache; and psychosocial function. Recurrences were observed in 17.6% of patients treated with radical surgery and in 42.8% of those treated with limited surgery plus radiotherapy. A progressive amelioration of visual, endocrine and neuropsychosocial functions from the intervention to follow-up was observed in the majority of patients. Complete tumor excision was associated in 85% of cases with a low score on the functional scale, reflecting a high functional performance. Adequate substitution therapy maintained endocrine balance in 81% of patients. Since the intervention a progressive decrease in the number and dosages of medications has been observed. The majority of patients were again able to lead a normal social life. Small stature, obesity, headache, and emotional and sexual disturbances were frequent cause of long-term disability even despite adequate drug regimens. The functional evaluation scale we propose is a simple and effective tool that can be easily used during routine evaluation of patients with craniopharyngioma