À descoberta de sofware para explorar a programação linear no ensino secundário

A Programação Linear, PL, tem como objectivo a resolução de problemas de optimização com restrições em que todas as funções envolvidas são lineares. Diversos problemas da vida real podem ser formulados como problemas de PL como, por exemplo, os problemas de planeamento e de transportes. A Programação Linear é um dos temas obrigatórios de algumas disciplinas de Matemática do Ensino Secundário, sendo importante que se trabalhem com os alunos problemas que traduzam situações reais, ou suas adaptações. Como estes problemas nem sempre são fáceis e rápidos de resolver, a utilização de ferramentas tecnológicas na sua resolução reveste-se de enorme importância. Existem diversos programas de computador como o Solver do Microsoft Office Excel, o WinQSB, o Programación Lineal e o Winplot, de fácil utilização pelos alunos, que possibilitam a exploração gráfica, no caso bidimensional, ou analítica dos problemas de PL. O uso deste software permite que os alunos resolvam uma maior diversidade de problemas e se centrem mais na análise e interpretação de resultados. Neste artigo, ilustra-se, resumidamente, a forma de resolver problemas de PL com o software mencionado e discute-se as suas potencialidades e limitações

INFLUENCE OF EMOTIONAL DETERMINANTS ON THE FOOD CHOICES OF THE PORTUGUESE

Food choices are influenced by many factors, such as emotional. When people eat, driven by emotional factors, they often lose control, which may lead to eating disorders. Therefore, this work aimed at studying the influence that emotional determinants had on people’s food choices. It was undertaken a descriptive cross-sectional study by means of a questionnaire on a non-probabilistic sample of 1314 participants. The data was collected among a sample of the Portuguese population and measured if people´s food choices were influenced by emotional determinants.The results revealed that the participants’ food choices were, in general, slightly influenced by emotional determinants (mean scores between –0.5 and 0.5, on a scale from –2 to +2). There were found significant differences in all of the variables under study. The participants, who already experienced an episode of binge-eating, were the ones that obtained the highest mean score (0.63±0.79), meaning that in this case those participants’ food choices were influenced by emotional determinants. These results support the premise that emotional determinants are influenced by the characteristics of each individual and also the existence of a positive association between emotional eating and the presence of eating disorders, especially, binge-eating

Linear programming knowledge in first stage higher education courses

In this work we will describe an experimental study with approximately fifty Portuguese students of the 2nd year of the BSc Degree of Biomedical Engineering as well as Chemical and Biological Engineering Higher Education Courses. The aims of this study are to identify which knowledge of Linear Programming (LP) taught in High School the students acquired and still remember, which tools they used in that stage of education when learning the theme of LP and their opinion about the significance of LP in daily life problem resolution. We also propose to investigate if the students are able to use WinQSB software to solve LP problems. In addition, we intend to identify not only the versatility of this software but also the opinion of the students about the resolution of LP problems with WinQSB, as well as their main difficulties during this experience

O Observatório Astronómico da Escola Politécnica : modelos virtuais para a sua preservação

O último observatório de ensino de interesse histórico em Portugal, que data do final do século XIX, é um dos edifícios mais carismáticos dos Museus da Universidade de Lisboa. Após um século de uso intensivo, o Observatório Astronómico da Escola Politécnica necessita de obras estruturais antes de ser devolvido integralmente à fruição pública. Recentemente, um grupo de estudantes desta Universidade foi envolvido na construção de modelos 3D virtuais para recriar o edifício do Observatório e alguns objetos das suas coleções. A qualidade dos modelos potencia a sua utilização como instrumento de divulgação de uma peça relevante do património histórico-científico da Universidade de Lisboa. Este artigo descreve as várias abordagens adoptadas e compara-as entre si.The Astronomical Observatory of the Lisbon Polytechnic School is the last teaching observatory of historical interest in Portugal. Created in the late nineteenth century, it survives intact in its original design. Given its singularity in the context of scientific heritage, the quality and beauty of its architecture, as well as its privileged location in the Botanical Garden, the Observatory has the potential to become the Museum’s focal point for the promotion of astronomy and its history. After 100 years of intense use, however, the Observatory is highly degraded and needs structural restoration before it can be fully returned to public fruition. Recently, three professors of the Faculty of Sciences of the University of Lisbon decided to involve a group of students in the construction of virtual 3D models to recreate the Observatory building and collections. This article describes the methods used to produce the models and presents a comparison between them

A Comprehensive Metabolic Profile of Cultured Astrocytes Using Isotopic Transient Metabolic Flux Analysis and 13C-Labeled Glucose

Metabolic models have been used to elucidate important aspects of brain metabolism in recent years. This work applies for the first time the concept of isotopic transient 13C metabolic flux analysis (MFA) to estimate intracellular fluxes in primary cultures of astrocytes. This methodology comprehensively explores the information provided by 13C labeling time-courses of intracellular metabolites after administration of a 13C-labeled substrate. Cells were incubated with medium containing [1-13C]glucose for 24 h and samples of cell supernatant and extracts collected at different time points were then analyzed by mass spectrometry and/or high performance liquid chromatography. Metabolic fluxes were estimated by fitting a carbon labeling network model to isotopomer profiles experimentally determined. Both the fast isotopic equilibrium of glycolytic metabolite pools and the slow labeling dynamics of TCA cycle intermediates are described well by the model. The large pools of glutamate and aspartate which are linked to the TCA cycle via reversible aminotransferase reactions are likely to be responsible for the observed delay in equilibration of TCA cycle intermediates. Furthermore, it was estimated that 11% of the glucose taken up by astrocytes was diverted to the pentose phosphate pathway. In addition, considerable fluxes through pyruvate carboxylase [PC; PC/pyruvate dehydrogenase (PDH) ratio = 0.5], malic enzyme (5% of the total pyruvate production), and catabolism of branched-chained amino acids (contributing with ∼40% to total acetyl-CoA produced) confirmed the significance of these pathways to astrocytic metabolism. Consistent with the need of maintaining cytosolic redox potential, the fluxes through the malate–aspartate shuttle and the PDH pathway were comparable. Finally, the estimated glutamate/α-ketoglutarate exchange rate (∼0.7 μmol mg prot−1 h−1) was similar to the TCA cycle flux. In conclusion, this work demonstrates the potential of isotopic transient MFA for a comprehensive analysis of energy metabolism

Environmental risk assessment in a contaminated estuary: an integrated weight of evidence approach as a decision support tool

Environmental risk assessment of complex ecosystems such as estuaries is a challenge, where innovative and integrated approaches are needed. The present work aimed at developing an innovative integrative methodology to evaluate in an impacted estuary (the Sado, in Portugal, was taken as case study), the adverse effects onto both ecosystem and human health. For the purpose, new standardized lines of evidence based on multiple quantitative data were integrated into a weight of evidence according to a best expert judgment approach. The best professional judgment for a weight of evidence approach in the present study was based on the following lines of evidence: i) human contamination pathways; ii) human health effects: chronic disease; iii) human health effects: reproductive health; iv) human health effects: health care; v) human exposure through consumption of local agriculture produce; vi) exposure to contaminated of water wells and agriculture soils; vii) contamination of the estuarine sedimentary environment (metal and organic contaminants); viii) effects on benthic organisms with commercial value; and ix) genotoxic potential of sediments. Each line of evidence was then ordinally ranked by levels of ecological or human health risk, according to a tabular decision matrix and expert judgment. Fifteen experts scored two fishing areas of the Sado estuary and a control estuarine area, in a scale of increasing environmental risk and management actions to be taken. The integrated assessment allowed concluding that the estuary should not be regarded as impacted by a specific toxicant, such as metals and organic compounds hitherto measured, but by the cumulative risk of a complex mixture of contaminants. The proven adverse effects on species with commercial value may be used to witness the environmental quality of the estuarine ecosystem. This method argues in favor of expert judgment and qualitative assessment as a decision support tool to the integrative management of estuaries. Namely it allows communicating environmental risk and proposing mitigation measures to local authorities and population under a holistic perspective as an alternative to narrow single line of evidence approaches, which is mandatory to understand cause and effect relationships in complex areas like estuaries.info:eu-repo/semantics/publishedVersio

Household sustainable consumption: an evaluation of environmental aawareness materials

European Union (EU) has been putting increasing emphasis on sustainable use and management of natural resources, especially since the adoption in 2001 of the EU Sustainable Development Strategy and the Sixth Environment Action Programme. Some objectives and priority areas for action are the achievement of a significant overall reduction in the volumes of waste generated through waste prevention initiatives, better resource exploitation efficiency and a shift towards more sustainable production and consumption patterns. There is wide global recognition that unsustainable patterns of consumption have serious social and environmental impacts. ‘Changing consumption patterns’, as identified by Chapter 4 of Agenda 21, remains a challenging, yet significant component of the drive to achieve sustainable development. Sustainable consumption does not mean about consuming less, it is about consuming differently, consuming efficiently, and having an improved quality of life. It also means sharing between the rich and the poor. The change of these consumption patterns could only be achieved through the use of correct and efficient environmental awareness/education campaigns. The purpose of the study is to conduct a state of the art of environmental awareness materials related with European household sustainable consumption. The search materials were compared and evaluated in terms of: aims; type of materials; target public; applicability and contents. The results of our research demonstrated that internet is a powerful tool and can contribute to the awareness of the general public about these issues. The problem of internet downloaded materials is the lack of their quality evaluation before them as available on the web. Weaknesses were found in terms of technical, scientific quality and their ability for learning-teaching. Some of them are very rudimentary, contributing little to the general public’s awareness. Also their interactivity could be better if taking into account the currently power of web base tools.info:eu-repo/semantics/publishedVersio

A subordinated stochastic process model

We introduce a new stochastic model for non-decreasing processes which can be used to include stochastic variability into any deterministic growth function via subordination. This model is useful in many applications such as growth curves (children’s height, fish length, diameter of trees, etc.) and degradation processes (crack size, wheel degradation, laser light, etc.). One advantage of our approach is the ability to easily deal with data that are irregularly spaced in time or different curves that are observed at different moments of time. With the use of simulations and applications, we examine two approaches to Bayesian inference for our model: the first based on a Gibbs sampler and the second based on approximate Bayesian computation (ABC)

A propósito do PIB: do crescimento para a sustentabilidade

Congresso realizado na Universidade de Évora, de 14-6 de abril de 2014O produto interno bruto (PIB) foi considerado uma das grandes invenções do século XX. As críticas que entretanto suscitou já conduziram, mais do que à formulação de complementaridades ou correcções, à proposta da sua abolição liminar. Apesar de se manter central na análise económica e definição de políticas, multiplicam-se as tentativas de afirmação de uma lógica alternativa, com a sustentabilidade como motivação e objectivo. A contestação da pretensa objectividade e auto-suficiência do PIB remete, por um lado, para a relatividade dos valores, desde logo para a designada ideologia do crescimento, e, por outro, para a escala da análise. Trata-se tanto de reconhecer a finitude dos recursos disponíveis, que compromete a ideia do crescimento infinito ou ‘sustentável’, como de convocar uma lógica sistémica que situe a economia, e, por maioria de razões, a finança, dentro da sociedade e esta dentro do ambienteGross domestic product (GDP) was deemed one of the great inventions of the 20th century. The criticisms the measure has since attracted have already led to the formulation of complementary or corrective versions rather than proposing its outright abolition. Despite remaining central to economic analysis and the definition of policies, attempts to affirm an alternative logic have proliferated with sustainability as their core underlying motivation and objective. The challenges to the intended objectivity and self-sufficiency of GDP on the one hand relate to the relativity of its values, from the outset the ideological dimension to growth, and, on the other hand, to the scale of analysis. This involves not only due recognition of the finitude of the resources available, and inherently compromising any idea of unending ‘sustainable’ growth, but also evoking a systemic logic that places the economy and, for an overwhelming number of reasons, finance within the scope of society that, in turn, remains within its own environmental boundaries.info:eu-repo/semantics/publishedVersio