Electric and magnetic fields effects on the excitonic properties of elliptic core-multishell quantum wires

The effect of eccentricity distortions of core-multishell quantum wires on their electron, hole and exciton states is theoretically investigated. Within the effective mass approximation, the Schrodinger equation is numerically solved for electrons and holes in systems with single and double radial heterostructures, and the exciton binding energy is calculated by means of a variational approach. We show that the energy spectrum of a core-multishell heterostructure with eccentricity distortions, as well as its magnetic field dependence, are very sensitive to the direction of an externally applied electric field, an effect that can be used to identify the eccentricity of the system. For a double heterostructure, the eccentricities of the inner and outer shells play an important role on the excitonic binding energy, specially in the presence of external magnetic fields, and lead to drastic modifications in the oscillator strength.Comment: 17 pages, 10 figure

Seismic vulnerability assessment of the old city centre of Seixal, Portugal

The seismic vulnerability assessment of old traditional masonry building stocks, in a seismic risk mitigation perspective, is truly essential not only for buildings with recognized historical and patrimonial value, but also, in relation to regular buildings. In this sense, this paper approaches the issue of the seismic vulnerability assessment of masonry buildings through the application of a simplified methodology to building stock of the old city centre of Seixal, Portugal. This methodology is based on a vulnerability index, suitable in the evaluation of damage and in the creation of large scale loss scenarios (economical and human). Over 500 buildings were evaluated in accordance with the referred methodology and the results obtained were then integrated into a Geographical Information System tool. The integration of this kind of vulnerability and loss results into a GIS tool allows that city councils or regional authorities make their decisions based on a global view of the site under analysis, which led to more accurate and faster decisions either in terms of risk mitigation strategies or rehabilitation plans. This tool can also assumes great importance in the construction of safety and rescue plans

Vulnerability assessment of urban building stock: a hierarchic approach

In the last decades the evaluation of the seismic risk are of rising concern, considered essential in the activity and definition of strategy planning and urban management. The evaluation of the seismic vulnerability of the existent building stock in the perspective of the seismic risk mitigation should not be placed only in relation to the isolated buildings of relevant historical and cultural importance, but also, in relation to the agglomerate of buildings in urban centres. The chronological construction process frequently results in characteristic heterogeneity of masonry and wall connection quality. In addition, buildings do not constitute independent units given that they share the mid-walls with adjacent buildings and the façade walls are aligned. This way, as post-seismic observations proved, buildings do not have an independent structural behaviour, but they interact amongst themselves, mainly for horizontal actions and so the structural performance should be studied at the level of the aggregate and not only for each isolated building. In most cases, for masonry structures there is no need for sophisticated dynamic analyses for seismic resistance verification or vulnerability assessment. This is even more relevant when an assessment at the level of a city centre is pursued. In this work, the results of evaluation of the vulnerability will be presented in accordance to three proposed methodologies based on a vulnerability index that consequently allows the evaluation of damage and creation of loss scenarios (economical and human) not only at the level of the building and its façade walls but also at the level of the aggregates. It will be discussed and evaluated the application of the referred methodologies and its integration in an SIG platform

Desenvolvimento e uso de um jogo didático "Corrida da Química" e sua implementação no ensino da química no 8º ano de escolaridade

A utilização de jogos didáticos no processo de ensino-aprendizagem da química é uma tendência recentemente proposta por vários autores. Esta abordagem pedagógica revela-se um útil instrumento para a promoção de aspectos relacionados com o desenvolvimento cognitivo, intelectual e criativo o que promove um acréscimo da motivação dos alunos para o processo de ensino. Consequentemente, considera-se que o uso destes instrumentos facilita a sociabilidade dos alunos, traduzindo-se num acréscimo das capacidades de interação pessoal, e contribui para promover o sucesso dos alunos na escola e na sociedade. Neste trabalho descrevem-se as etapas de construção de um jogo didático, intitulado “Corrida da Química” sendo este utilizado como suporte de aprendizagem da unidade didática “Reações Químicas". O processo de elaboração do jogo envolveu a construção dos vários componentes, nomeadamente: o tabuleiro do jogo (baseado na Tabela Periódica dos Elementos); os conjuntos de cartões; os modelos de equipamento de laboratório; modelos atómicos e peças de puzzle de modelos de iões. Serão apresentados os resultados da implementação de dois testes (teste inicial e teste final) que avaliaram o impacto do jogo no processo de aprendizagem permitindo concluir que este jogo contribuiu para uma melhoria do aproveitamento e uma participação mais ativa dos aluno