Some remarks on the attractor behaviour in ELKO cosmology

Recent results on the dynamical stability of a system involving the interaction of the ELKO spinor field with standard matter in the universe have been reanalysed, and the conclusion is that such system does not exhibit isolated stable points that could alleviate the cosmic coincidence problem. When a constant parameter $\delta$ related to the potential of the ELKO field is introduced in the system however, stable fixed points are found for some specific types of interaction between the ELKO field and matter. Although the parameter $\delta$ is related to an unknown potential, in order to satisfy the stability conditions and also that the fixed points are real, the range of the constant parameter $\delta$ can be constrained for the present time and the coincidence problem can be alleviated for some specific interactions. Such restriction on the ELKO potential opens possibility to apply the ELKO field as a candidate to dark energy in the universe, and so explain the present phase of acceleration of the universe through the decay of the ELKO field into matter.Comment: 17 pages, section III with minor changes and section IV rewritten with a new analysi

A web-based hydroinformatic platform for water quality modelling in a river basin

This paper presents a hydroinformatic platform specifically designed for a Portuguese north-western river basin (river Cávado) in order to define, simulate and analyze hydrodynamics and water quality management scenarios. The software solution was designed to be operated in a web environment, taking advantage of the integration capabilities of this software environment and the user friendliness of web interfaces

Simulation of biomass gasification in circulating fluidized bed reactor by aspen plus

Biomass is the fourth largest source of energy in the world. Many consider it to be the best option, with the greatest potential as an alternative energy supply which meets energy requiremen ts, for ensuring future fuel supply. Biomass energy resources are potentially the world's largest and most sustainable energy source, a renewable resource comprising 220 billion oven-dry tons (about 4500 EJ) of annual primary production [1]. lt is currently assumed that 5% of this energy could be mobilized to produce energy, i.e. a total of 225 EJ representing an energy equivalent ofmore than 5 billion tons ofoil equivalent, accounting for almost 50% ofthe world's total primary energy demand at present [2]. Hydrogen production is one of the most promising alternative energy technologies . The majority of experts consider that hydrogen has a significant role to play as an important energy carrier in the future energy sector [3]. Howe ver, it is a secondary form of energy that, like electricity, must be manufactured. A promising way to generate hydrogen is by thermochemical conversion of biom ass to synthe sis gas , consisting of a mixture of H2, CO, C0 2, CH.i, 0 2, N2 and tar. ln order to maximize H2 yield, an Or steam circulating fluidized bed (CFB) gasification process was proposed. For this purpose a computer simulation model was developed using the commercial chemical process simulator ASPEN Plus.N/

Ferramenta de modelação desenvolvida em ambiente web para apoio à gestão de albufeiras

A utilização das tecnologias de informação e comunicação no caso específico da gestão de recursos hídricos, em que a incerteza associada aos processos hidrológicos determina um grau de dificuldade acrescido, revela-se essencial. Desta forma, o desenvolvimento de ferramentas que permitam a consulta de dados de redes de monitorização hidrológica, de previsões meteorológicas e de resultados de simulação em ambientes de múltiplas plataformas, fixas ou móveis, é uma das tarefas fundamentais para a incorporação das tecnologias de informação nos processos correntes de gestão de recursos hídricos. No presente trabalho apresenta-se uma ferramenta, desenvolvida para ambiente web, que permite consultar informação e operar modelos hidráulicos de simulação de barragens e respetivas albufeiras. A interface é adaptável a cada caso de estudo e poderá ser desenvolvida com diferentes tipos de software de modelação hidrológica e hidrodinâmica, considerando as necessidades estabelecidas pelo conjunto dos seus utilizadores. A partir da interface é possível estabelecer as condições de fronteira definidas para cada modelo, aplicar o modelo e visualizar os resultados de simulações dinâmicas. A aplicabilidade da ferramenta desenvolvida é demonstrada em exemplos de implementação em diversas albufeiras situadas no rio Guadiana (Empreendimento de Fins Múltiplos de Alqueva, Portugal

The respiratory chain inhibitor rotenone affects peroxisomal dynamics via its microtubule-destabilizing activity

This is the author accepted manuscript. The final version is available from Springer Verlag via the DOI in this record.Peroxisomes and mitochondria in mammalian cells are closely linked subcellular organelles, which maintain a redox-sensitive relationship. Their interplay and role in ROS signalling is supposed to impact on age-related and degenerative disorders. Whereas the generation of peroxisome-derived oxidative stress can affect mitochondrial morphology and function, little is known about the impact of mitochondria-derived oxidative stress on peroxisomes. Here, we investigated the effect of the mitochondrial complex I inhibitor rotenone on peroxisomal and mitochondrial membrane dynamics. We show that rotenone treatment of COS-7 cells alters peroxisome morphology and distribution. However, this effect is related to its microtubule-destabilising activity rather than to the generation of oxidative stress. Rotenone also induced alterations in mitochondrial morphology, which – in contrast to its effect on peroxisomes - were dependent on the generation of ROS but independent of its microtubule-active properties. The importance of our findings for the peroxisome-mitochondria redox relationship and the interpretation of in cellulo and in vivo studies with rotenone, which is widely used to study Parkinson’s disease, are discussed.We would like to acknowledge the support of T. A. Schrader, N. A. Bonekamp and J. Jordan (University of Castilla-La Mancha, Albacete, Spain). This work was supported by the Biotechnology and Biological Sciences Research Council (BB/K006231/1, BB/N01541X/1 to M.S.), the Portuguese Foundation for Science and Technology and FEDER/COMPETE (SFRH/BPD/37725/2007 to M.G.L), the University of Aveiro, PT and CLES, University of Exeter, UK. M.S. is supported by a Marie Curie Initial Training Network (ITN) action PerFuMe (316723)

Sistema de informação para avaliação das afluências de águas interiores à zona costeira do Concelho de Matosinhos

No presente artigo apresenta-se um Sistema de Informação (SI) desenvolvido para caracterizar as águas interiores afluentes ao litoral do concelho de Matosinhos e para suporte ao desenvolvimento de modelos matemáticos que permitam avaliar as áreas de influência e magnitudes das respectivas descargas. O SI foi construído com base em informação existente e em informação complementar obtida através de campanhas pontuais de medição nos locais de descarga. O sistema desenvolvido será utilizado quer na caracterização da qualidade da água quer na construção de modelos matemáticos de simulação da hidrodinâmica e qualidade da água