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Abstract
The collaborative virtual worlds can be used to achieve different purposes according to the intended use. The design of 3D collaborative virtual environments for learning has been an important research field for several years. However, the research in this specific field has shown that in most of the cases, the environments do not have appropriate technical characteristics. The design of the educational collaborative virtual environments goal is to produce environments that encourage users to achieve effective learning. In this sense, the current study presents a design model for development of 3D Educational Collaborative Virtual Environments. This model is based on the engineering software techniques and methods. It is supported by a spiral cycle that allows us to develop applications. The process is divided into a set of activities that are being carried out throughout each cycle, producing several work products, with the aim to provide each team member a set of guidelines and tools necessary for to make intelligent decisions about what they do. The model is composed by five steps, namely: Conception, Analysis, Design, Implementation and Evaluation. Each step contains a set of diagrams to support the developer team in their tasks. With this model, the applications are developed in a series of incremental releases, that is, the final system is constructed, based on the refined prototype. These steps include activities that enable to quantify the quality of Educational Collaborative Virtual Environments (ECVE). It is based on the Quantitative Evaluation Framework developed by Escudeiro (Escudeiro, 2007) and allow us to have a degree of freedom in the selection of quality criteria. Thus, we can obtain a single quantitative value of quality for any domain in analysis, i.e., we can adapt it in any domain and valence.

Abstract
Self-efficacy refers to the beliefs in the ability to organise and implement the action plans needed to achieve a certain result and the feeling of control over the behaviours and environment. It determines the initiation, maintenance and cessation of strategies or behaviours, being a good predictor of eating behaviour. Despite its potential in terms of research, prognosis and evaluation of interventions, we are unaware of instruments to assess global features of food self-efficacy validated for the Portuguese population. The aim of this work is to develop and validate a scale to assess general features of food self-efficacy ("Escala de Auto-Eficácia Alimentar Global"). We evaluated a sample of 276 higher education students, and the analysis was performed separately for the subsamples of females and males. The items were created through the adaptation of the six items of the self-efficacy subscale of the "Inventário Clínico de Auto-Conceito" (Serra, 1986). The analysis led to the maintenance of five of the six items initially considered. The scale shows an unifactorial structure, and the proportion of total variance explained by the principal components extracted is higher than 64%. It also shows good internal consistency, with values of Cronbach's alpha above 0.85. The study of relations with other measures showed evidence of its convergent and discriminant validities. The "Escala de Auto-Eficácia Alimentar Global" may prove to be an useful tool for the prognosis and the evaluation of interventions related to the change in eating habits.

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Large-scale integration of distributed energy resources in low voltage distribution grids will have a serious impact on power system operation. The development of the microgrid concept is presented as a solution to overcome some of the negative impacts of massive microgeneration deployment. It has paved the way for an active network management approach within the smart grid paradigm. The microgrid concept is able to address the integration of geographically dispersed energy resources, thus avoiding significant technical problems that may affect the security of operation. (C) 2012 John Wiley & Sons, Ltd.