Serial correlation in dynamic panel data models with weakly exogenous regressor and fixed effects

Our paper wants to present and compare two estimation methodologies for dynamic panel data models in the presence of serially correlated errors and weakly exogenous regressors. The ¯rst is the ¯rst di®erence GMM estimator as proposed by Arellano and Bond (1991) and the second is the transformed Maximum Likelihood Estimator as proposed by Hsiao, Pesaran, and Tahmiscioglu (2002). Thereby, we consider the ¯xed e®ects case and weakly exogenous regressors. The ¯nite sample properties of both estimation methodologies are analysed within a simulation experiment. Furthermore, we will present an empirical example to consider the performance of both estimators with real data. JEL Classification: C23, J6

Arguments towards a humanization of science

Identificando a rutura no desenvolvimento da ciência entre o contexto de descoberta e o contexto de justificação, julgamos poder entender melhor a dominação do ensino transmissivo da ciência em contexto escolar e melhor argumentar para a sua superação. Por outro lado, o argumento que aqui defendemos para recuperar, para o contexto de sala de aula, a fortíssima chama cultural que a ciência transporta nos seus conceitos, leis e teorias, bem como no seu próprio processo de desenvolvimento, tem uma tradição enraizada na cultura portuguesa que exploramos.ABSTRACT By identifying the rupture in the development of science between the context of discovery and the context of justification, we believe can better understand the domination of transmissive teaching of science in schools and argue for overcoming it. The argument is to recover for the classroom the very strong cultural flame that science carries in its concepts, laws and theories as well as in its own developmental processes. We explore the tradition rooted in Portuguese culture

the socio-cultural animator in a science based society

An education promoting scientific literacy (SL) that prepares the citizens to a responsible citizenship has persisted as an argument across discussions on curricula design. The ubiquity of science and technology on contemporary societies and the ideological requirement of informed democratic participation led to the identification of relevant categories that drive curriculum reforms towards a humanistic approach of school science. The category ‘Science as culture’ acquires in the current work a major importance: it enlightens the meaning of scientific literacy. Looking closely to the French term, culture scientifique et tecnologique, turns science simultaneously into a cultural object and product that can be both received and worked at different levels and within several approaches by the individuals and the communities. On the other hand, nonformal and informal education spaces gain greater importance. Together with the formal school environment these spaces allow for an enrichment and diversification of learning experiences. Examples of nonformal spaces where animators can develop their work may be science museums or botanical gardens; television and internet can be regarded as informal education spaces. Due to the above mentioned impossibility of setting apart the individual or community-based experiences from Science and Technology (S&T), the work in nonformal and informal spaces sets an additional challenge to the preparation of socio-cultural animators. Socio-scientific issues take, at times, heavily relevance within the communities. Pollution, high tension lines, spreading of diseases, food contamination or natural resources conservation are among the socio-scientific issues that often call upon arguments and emotions. In the context of qualifying programmes on socio-cultural animation (social education and community development) within European Higher Education Area (EHEA) the present study describes the Portuguese framework. The comparison of programmes within Portugal aims to contribute to the discussion on the curriculum design for a socio-cultural animator degree (1st cycle of Bologna process). In particular, this study intends to assess how the formation given complies with enabling animators to work, within multiple scenarios, with communities in situations of socio-scientific relevance. A set of themes, issues and both current and potential fields of action, not described or insufficiently described in literature, is identified and analysed in the perspective of a qualified intervention of animators. One of these examples is thoroughly discussed. Finally, suggestions are made about curriculum reforms in order, if possible, to strongly link the desired qualified intervention with a qualifying formation

Synchronization of coupled oscillators

Tese de mestrado em Física (Física Estatística e Não Linear), apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2010In this work we begin by introducing the Kuramoto model, constructing its solutions in the thermodynamic limit and showing the close connection between statistical physics and dynamical systems that lead to the main theoretical insights. The systematic study of a finite population of self sustained oscillators began in the first decade of this century. Unlike most of the papers we have found, we are not interested in the synchronization transition in itself but rather in phase locked patterns and their relation with frequency distribution among oscillators. The problem of stability, as we have already mentioned, experienced great advances in recent years. In a brief discussion we only address the problem of stability of the simplest solution allowed by the Kuramoto model: the incoherent solution. After that we introduce chimera states, first noticed by Kuramoto and his colleagues ([17] and references therein), in which the introduction of a non local coupling gives origin to a split in a region with synchronised oscillators and other with asynchronous one. Then we proceed by exploring the literature and the results with a finite number of oscillators, field explored with persistence only since mainly 2004 [29]. But here we are yet in Kuramoto framework which is abandoned, in a rigorous terminology, when we pursuit structured and not all-to-all coupling. Although we could introduce the same mean fields quantities if well defined in each situation, this did not help us in making sense of the results and is not an help in any analytical work. In our analysis of a ring of coupled oscillators we construct a space that allows us to relate the stable solutions with the eigenvectors of the laplacian of the graph in which we work.Neste trabalho começamos por introduzir o modelo de Kuramoto e realizar a construção das suas soluções no limite termodinâmico, mostrando a relação estreita entre física estatística e sistemas dinâmicos que levaram aos desenvolvimentos mais significativos. O estudo sistemático das populações de osciladores com um número finito de elementos começaram na primeira década deste século. Ao contrário de muitos trabalhos nesta área, não estamos interessados no processo de sincronização em si mas antes em padrões de fases que surgem em sincronia e sua relação com a distribuição das frequências próprias entre osciladores. O problema da estabilidade das soluções teve grandes desenvolvimento nos últimos anos. Numa breve análise apenas atendemos ao problema da estabilidade da mais simples solução do modelo de kuramoto: a solução incoerente. Depois introduzimos as quimeras, estados de sincronização descobertos por Kuramoto e que resultam da introdução de acoplamento não local, resultando numa separação entre uma zona de sincronia e uma zona assíncrona num mesmo sistema. Prosseguimos analisando a literatura e os resultados conhecidos com um número finito de osciladores, um campo explorado de forma sistemática apenas após, grosso modo, 2004. Abandonamos o modelo de Kuramoto quando passamos ao estudo de um número finito de osciladores e introduzimos acoplamentos estruturados saindo do acoplamento de todos com todos. Nesta situação as quantidades de campo médio, na origem do êxito do modelo de Kuramoto, ficam sem utilidade evidente, ainda que caso a caso se possam ainda definir e trabalhar. A nossa análise num círculo onde os osciladores acoplam entre primeiros vizinhos e construímos um espaço onde podemos visualizar a relação entre as soluções estáveis e os vectores próprios do operador Laplaciano do grafo associado

Pre-service teachers ideas of collaborative work when using a wiki to construct a lab notebook

Due to the potential benefits of the wikis, they are increasingly gaining popularity in educational settings. In the educational context they have been used for various purposes such as managing research projects, publishing course materials and completing writing assignments. This type of Web 2.0 tool provides a number of useful functions, such as creation of content by multiple users, tracking history of users’ actions, comparison between different editions and roll-back to earlier versions of the wiki, allowing teachers to monitor learners’ co-authoring process. Because of these functions, wikis have been claimed as facilitators of collaborative writing, group discussion and interaction. However, wikis are not inherently collaborative. After a brief review of the relevant literature on the importance of interaction in the learning process this communication presents some preliminary results on the use of wikis by pre-service elementary school teachers. The implementation of virtual lab notebooks hosted within a wiki environment in the scope of a course on biology is described. Students´ perceptions regarding the implementation of the wiki are explored, namely its challenges and potential benefits. In order to achieve this goal, participants were asked to write a reflexive essay about their use of the wiki. A content analysis on this data followed. An additional goal is to understand the kind of interaction promoted by the wiki. For this purpose, the individual contributions to the wiki that occurred during the learning process were analyzed and categorized. Follow-up interviews were conducted to gain insight into students’ decisionmaking process. The results are discussed in view of identifying factors that may lead to a more successful integration of the wikis in science lessons and to improve pre-service teachers’ confidence in using Web 2.0 tools for pedagogical purposes.info:eu-repo/semantics/publishedVersio

A novel approach to understanding CoViD-19: exploring the interplay of SARS-CoV-2 and CTL response

Facing a global challenge with over 6.9 million fatalities, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of CoViD-19, demands novel and comprehensive approaches to understand its complex dynamics. This paper introduces a non-integer order model, capturing the intricate interplay between SARS-CoV-2 and the host's cytotoxic T lymphocytes (CTLs) response. Our work reveals a unique parameter space, in which an endemic state of SARS-CoV-2 and a CTL response-free equilibrium can coexist -- a crucial finding in our quest to decipher this pervasive virus. We further explore the basic reproduction number, assessing how different model parameters can potentially inhibit or fuel the infection's progression. Through extensive numerical simulations, we scrutinize the impact of varying the order of the fractional derivative and employing diverse CTL proliferation functions. This study significantly enriches our understanding of CoViD-19 immunopathology, offering invaluable insights that could guide future research and therapeutic strategies

Evaluation of the cytotoxic potential of adhesives, with two on the market: Scotchbond Universal and Optibond Solo Plus, and an adhesive in the experimental phase: T1

Communication abstract: Proceedings of the 5th International Congress of CiiEM - Reducing inequalities in Health and Society, held at Egas Moniz’ University Campus in Monte de Caparica, Almada, from June 16th to 18th, 2021.This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.In vitro studies evaluating the cytotoxic potential of substances released from dental adhesives are lacking. The purpose of this study was to compare the cytotoxicity of the extracts of dental adhesives Scotchbond Universal and Optibond Solo Plus, and an adhesive in the experimental phase: T1. 3T3 mouse fibroblast cells and MG-63 osteoblast-like cells from human osteosarcoma were exposed for 24 h to serial extract dilutions. Cytotoxicity was determined using an MTT assay. For both cell lines, the cytotoxicity order obtained, of the unfiltered adhesive extracts, was T1 (less cytotoxic) < Optibond Solo Plus < Scotchbond Universal (most cytotoxic).info:eu-repo/semantics/publishedVersio

Análise comparativa da performance mastigatória entre doentes portadores de prótese parcial removível acrílica e esquelética

Objectives: To perform a comparative analysis of the masticatory performance between patients with acrylic versus metal removable partial dentures. Methods: 20 subjects participated in this study: 10 with a bimaxillary acrylic removable partial denture (PA group) and 10 with a bimaxillary metal removable partial denture (PE group). The subjects were aged between 49 and 79 years old and included 12 females and 8 males. A system of 7 granulometric sieves was employed, and an artificial food was elaborated. Each participant chewed 20 cubes of the artificial food: 10 cubes in a first masticatory cycle of 20 strokes and 10 cubes in a second masticatory cycle of 40 strokes. After chewing, each patient disposed of the food into a container. A particle size analysis, using a sieves system, was performed to determine the geometric mean particle diameter (GMD). The sample's results were submitted to the Kolmogorov-Smirnov and Shapiro-Wilk normality tests. The student t- test was then performed to compare the mean GMD in the PA and PE groups, considering a significance level of 0.05. Results: Statistically significant differences were verified between the mean GMD of the PA group and the PE group, both for the 1st masticatory cycle (p <0.001) and for the 2nd masticatory cycle (p <0.001). The PA group's mean GMD values were higher than those of the PE group in the two masticatory cycles. Conclusion: A difference was verified in the masticatory performance between patients with acrylic versus metal removable partial dentures.info:eu-repo/semantics/publishedVersio

O estudo de aula na Formação Inicial: Desenvolvimento de processos colaborativos

O Estudo de Aula tem sido usado na formação contínua de professores um pouco por todo o mundo. Contudo, a sua utilização na formação inicial de professores ainda é pouco estudada. Em Portugal, têm tido lugar algumas investigações no ensino das ciências sobre a implementação do Estudo de Aula na formação inicial, sendo neste âmbito que o nosso trabalho se enquadra. Os estudos têm demonstrado potencialidades do processo no desenvolvimento do conhecimento pedagógico de conteúdo (PCK) dos futuros professores, na promoção dos processos colaborativos, na mudança de foco das ações do (futuro) professor para as atividades e aprendizagens dos alunos. São ainda reportadas aprendizagens nos professores cooperantes participantes no processo. O Content Represention Knowledge (CoRe), que inicialmente foi mais usado para explorar o PCK de professores experientes, tem vindo a ser utilizado, no âmbito da formação inicial de professores, com o objetivo de promover o desenvolvimento do PCK. O CoRe permite uma maior integração da teoria e da prática, aceder a aspetos mais tácitos dos professores cooperantes e assim exibir conhecimento pedagógico e didático muitas vezes não explicitado. Investigamos, utilizando uma análise narrativa, o efeito do uso do CoRe num Estudo de Aula centrado no sistema cardiovascular desenvolvido no âmbito da Prática de Ensino Supervisionada no 2.º CEB de uma escola de Lisboa, centrando a nossa análise no envolvimento da Professora Cooperante. Apresentamos evidências que mostram um processo genuinamente colaborativo envolvendo todos os participantes. A professora cooperante mostra ganhos no entendimento do processo formativo relativamente à sua prática usual.Abstract Lesson study has been used in in-service teachers' training worldwide. However, its use in initial teachers' training is still poorly studied. In Portugal, some investigations have taken place about the implementation of lesson studies in initial teachers' training, and it is in this context that our work fits. The studies have demonstrated the potential of the process in developing pedagogical content knowledge (PCK) of future teachers, promoting collaborative processes, and moving future teachers' sole focus away from teacher actions toward student learning. Studies also evidence learning for participating mentors. Content Representation Knowledge (CoRe), which was initially used to explore the PCK of experienced teachers, has been used in the context of initial teacher education to promote the development of the PCK. CoRe allows for greater integration of theory and practice, accessing more tacit aspects of mentor teachers and thus displaying pedagogical and didactic knowledge that is often not made explicit. Using narrative analysis, we investigated the effect of the use of CoRe in a lesson study focused on the cardiovascular system developed within the scope of the supervised teaching practice in the sixth grade of a school in Lisbon, focusing our analysis on the involvement of the mentor teacher. We present evidence that shows a genuinely collaborative process involving all participants. The mentor teacher shows gains in the understanding of the training process in relation to her usual practice.info:eu-repo/semantics/publishedVersio