ESTGV - DMAT - Artigo em revista científica, não indexada ao WoS/Scopus
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- O ABC do Geometer's SketchpadPublication . Duarte, Isabel; Cavaleiro, JoãoO Geometer’s Sketchpad, sendo um software de geometria dinâmica permite-nos abordar conceitos de geometria de uma maneira inovadora.
- Calculadoras Gráficas na MatemáticaPublication . Duarte, Fernando; Duarte, Isabel; Dias, TeresaAlguns dos objectivos gerais do programa de Matemática do Ensino Secundário são: Interpretar fenómenos e resolver problemas recorrendo a funções e seus gráficos; Exprimir o mesmo conceito em diversas formas e linguagens; Analisar situações da vida real, identificando modelos matemáticos que permitam a sua interpretação e resolução; Formular generalizações a partir de experiências, estando em todos eles presente a dimensão gráfica, sendo por isso indispensável o uso da calculadora gráfica.
- Comparison of decision rules to mediate negotiations with incomplete informationPublication . Sarabando, Paula; Dias, LuísDecisions in society resulting from negotiation among two parties are often inefficient (in terms of Pareto efficiency) as the parties fail to identify an agreement that would make both better off. A third party mediating the negotiation can increase the chances of reaching a Pareto efficient alternative. However, in most practical situations the mediator does not have a precise model of the parties’ preferences, and therefore cannot identify which alternatives are efficient. This paper assesses the performance of decision rules that a mediator can apply in multi-issue bilateral negotiation analysis given ordinal information about the importance of the issues and the value of the potential alternatives in each issue. We assume the preferences of the parties can be modelled by an additive multiattribute value function, but without assuming the precise parameters of this model are known. We study three mediation criteria: maximising the sum of the values, maximising the product of the excesses, or maximising the minimal proportion of potential. Monte-Carlo simulation is used to assess how good the alternative chosen by each decision rule is, and to provide guidelines about the use of these rules in a context of selecting a subset of promising alternatives.
- Conflitos Conjugais e a EstatísticaPublication . Henriques, Carla; Duarte, FernandoNesta sessão pretendíamos "jogar" com a Estatística, criando um cenário fictício que possibilitasse a aplicação de algumas técnicas da inferência estatística
- Controlo de Robots RedundantesPublication . Duarte, FernandoUm robot redundante é um sistema que pode apresentar várias (ou, até, uma infinidade de) configurações para uma determinada posição do órgão terminal no espaço cartesiano. Assim, sob o ponto de vista cinemático, estes mecanismos introduzem uma grande versatilidade pois permitem a resolução de tarefas minimizando esforços, evitando eventuais obstáculos e eliminando singularidades indesejáveis. Embora estes robots apresentem as vantagens referidas, a utilização destes mecanismos ainda é pouco frequente. De facto, o controlo destes sistemas envolve modelos matemáticos sofisticados, aumentando a sua complexidade com o número de graus de liberdade.
- Critérios de diagnóstico da Síndrome de Brugada. Podemos melhorar?Publication . Santos, Luís Ferreira; Pereira, Telmo; Rodrigues, Bruno; Correia, Emanuel; Moreira, Davide; Nunes, Luís; Costa, António; Elvas, Luís; Machado, José Carlos; Castedo, Sérgio; Henriques, Carla; Matos, Ana; Santos, OliveiraDiagnosis of Brugada syndrome (BS) currently requires documentation of a characteristic repolarization pattern (type 1 Brugada ECG). Mutations in the SCN5A gene, which codes for sodium channel Na(v) 1.5, are found in 38% of familial cases of BS. Sodium current dysfunction negatively affects the cardiac fast response action potential, particularly in atrial and ventricular myocytes and in the fast-conducting Purkinje system.
- Derivation and validation of the SLE Disease Activity Score (SLE-DAS): a new SLE continuous measure with high sensitivity for changes in disease activityPublication . Jesus, Diogo; Cristina Bico Rodrigues de Matos, Ana; Henriques, C.; Zen, Margherita; Larosa, Maddalena; Iaccarino, Luca; Da Silva, José António Pereira; Doria, Andrea; Inês, Luís SousaObjectives To derive and validate a new disease activity measure for systemic lupus erythematosus (SLE), the SLE Disease Activity Score (SLE-DAS), with improved sensitivity to change as compared with SLE Disease Activity Index (SLEDAI), while maintaining high specificity and easiness of use. Methods We studied 520 patients with SLE from two tertiary care centres (derivation and validation cohorts). At each visit, disease activity was scored using the Physician Global Assessment (PGA) and SLEDAI 2000 (SLEDAI-2K). To construct the SLE-DAS, we applied multivariate linear regression analysis in the derivation cohort, with PGA as dependent variable. The formula was validated in a different cohort through the study of: (1) correlations between SLE-DAS, PGA and SLEDAI-2K; (2) performance of SLEDAI-2K and SLE-DAS in identifying a clinically meaningful change in disease activity (ΔPGA≥0.3); and (3) accuracy of SLEDAI-2K and SLE-DAS time-adjusted means in predicting damage accrual. Results The final SLE-DAS instrument included 17 items. SLE-DAS was highly correlated with PGA (r=0.875, p<0.0005) and SLEDAI-2K (r=0.943, p<0.0005) in the validation cohort. The optimal discriminative ΔSLE-DAS cut-off to detect a clinically meaningful change was 1.72. In the validation cohort, SLE-DAS showed a higher sensitivity than SLEDAI-2K (change ≥4) to detect a clinically meaningful improvement (89.5% vs 47.4%, p=0.008) or worsening (95.5% vs 59.1%, p=0.008), while maintaining similar specificities. SLE-DAS performed better in predicting damage accrual than SLEDAI-2K. Conclusion SLE-DAS has a good construct validity and has better performance than SLEDAI-2K in identifying clinically significant changes in disease activity and in predicting damage accrual.
- Discrete-time fractional variational problemsPublication . Bastos, N. R. O.; Ferreira, R. A. C.; Torres, D. F. M.We introduce a discrete-time fractional calculus of variations on the time scale (hℤ)a,a∈ℝ,h>0. First and second order necessary optimality conditions are established. Examples illustrating the use of the new Euler-Lagrange and Legendre type conditions are given. They show that solutions to the considered fractional problems become the classical discrete-time solutions when the fractional order of the discrete-derivatives are integer values, and that they converge to the fractional continuous-time solutions when h tends to zero. Our Legendre type condition is useful to eliminate false candidates identified via the Euler-Lagrange fractional equation. © 2010 Elsevier B.V. All rights reserved.
- Do consumers judge a book by its cover? A study of the factors that influence the purchasing of booksPublication . Leitão, Luís; Amaro, Suzanne; Henriques, Carla; Fonseca, PaulaResearch addressing the critical success factor of books and how people choose them is scarce. This study examines the factors that influence consumers when purchasing fictional books and explores whether there are differences between purchasing books for personal use or as gifts. Furthermore, it also studies mpulsiveness regarding the purchase. A quantitative empirical analysis was conducted based on 487 valid responses obtained through an online questionnaire. The results of this study show that approximately one third of books are purchased as gifts, women buy and read more books than men and higher educated and older consumers tend to read and buy more books. The purchase is less impulsive when the book is a gift and women are more impulsive, when buying for themselves. In the decision-making process, the features most valued in a book are: the "Title”, "Synopsis”, “Subject covered in book”, “Recommendation of family and friends” and “Books with discount/on sale”. Twenty-four items were considered based on these features and the same factor structure was found for both buying books for personal use and as gifts. Consumers tend to value more the “Recommendation of family and friends” when buying a book for themselves rather than as a gift. However, “Author and book recognition” is more important to the consumer when the book is purchased as a gift. The findings of this study provide important insights regarding consumer preferences, which will be useful for marketers to define strategies. Moreover, by comparing the factors that influence people to buy books for themselves as opposed to buying them as gifts, bookstores can strive to satisfy consumer demands, by conceiving and implementing new ideas in order to increase their book sales.
- Estudar Funções Utilizando o Cabri GéomètrePublication . Duarte, IsabelHá indicações metodológicas nos programas do 3º Ciclo do Ensino Básico e do Ensino Secundário para a utilização em sala de aula, sempre que possível, de computadores, pelo que se torna de grande relevância a participação dos professores em sessões relacionadas com a utilização destas tecnologias. O Cabri Géomètre é um software de geometria dinâmica que permite a exploração dos objectos da geometria e das suas relações. Este programa permite também tratar as construções geométricas em coordenadas cartesianas, o que nos vai permitir estudar famílias de funções.