IMEF - Artigos publicados em periódicos

URI permanente para esta coleçãohttps://rihomolog.furg.br/handle/1/341

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Sixth form students ability to engage in computational modelling
(1994) Santos, Arion de Castro Kurtz dos; Ogborn, Jon
The paper presents the main conclusions of an exploratory study of the ability of Sixth form students in England to use some different approaches to computational modelling. The research involves a questionnaire survey of causal diagraming and mathematical knowledge, which aims at characterizing students' model building capability. Also, it includes an intensive study with pairs of students doing exploratory and expressive tasks using two modelling systems: IQON and STELLA. Data was gathered through written notes from observation, written answers given to questionnaires and data recorded in the computer. Overlapping questionnaires connected the survey and the intensive study, and comparisons between the use of causal diagrams and IQON were carried out. Results suggest that Sixth form students can undertake valuable work with both computational systems.
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Uma experiência em pequena escala sobre o potencial da modelagem semiquantitativa para a educação ambiental
(1995) Santos, Arion de Castro Kurtz dos; Kleer, Ana Alzira; Thielo, Marcelo Resende; Gravina, Maria Helena
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Modelagem como aprendizado e o papel do mestre em educação ambiental
(1997) Santos, Arion de Castro Kurtz dos
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A física utilizada na investigação de acidentes de trânsito
(1997) Kleer, Ana Alzira; Thielo, Marcelo Resende; Santos, Arion de Castro Kurtz dos
Visando o ensino de Física de uma maneira mais atrativa aos alunos de 2° e 3° graus, desenvolvemos um programa que permite utilizar alguns tópicos de Mecânica na Investigação de Acidentes de Trânsito. Como precisávamos conhecer o coeficiente de atrito, construímos um aparelho para tal e, utilizando dados a respeito de marcas de derrapagem, coeficientes de atrito para diferentes pontos, raios de curvas, etc. colhidos na BR-392 que liga as cidades de Rio Grande e Pelotas, pudemos testar o programa e, com o auxílio de bibliografia adequada, verificar a validade de nossas estimativas. Os resultados obtidos mostram que o programa IAT pode ser utilizado por estudantes e professores de Física, bem como por investigadores de trânsito, possibilitando o aprendizado da Física e auxiliando nas investigações de acidentes e na conscientização em relação à segurança no trânsito.
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Students modelling environmental issues
(1997) Santos, Arion de Castro Kurtz dos; Thielo, Marcelo Resende; Kleer, Ana Alzira
This work is based on a Brazilian project that aims to promote the use of a semi-quantitative tool with students (11 - 18 years old) in topics about local environmental problems. The paper presents the VISQ program, a network to analyse models, a set of tasks and three examples of models made by students. Results suggest that the VISQ program is suitable for use in Environmental Education as while working with the proposed tasks students thought at a system level becoming aware of some local environmental issues.
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Utilização da ferramenta computacional visq e a validação de modelos semiquantitativos
(1998) Santos, Arion de Castro Kurtz dos; Araújo, Ives Solano; Gonçalves, Geovane Pedra
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A modelagem semiquantitativa e o pensamento sistêmico sobre um problema ambiental (versão completa de artigo)
(1999) Santos, Arion de Castro Kurtz dos; Gonçalves, Geovane Pedra; Araújo, Ives Solano
O trabalho aqui relatado objetiva promover a utilização de uma ferramenta de modelagem semiquantiativa chamada visq (acrônimo para variáveis que interagem de modo semiquantitativo) por estudantes em tópicos sobre problemas ambientais locais. Os resultados sugerem que após o trabalho com o visq, os estudantes teriam evoluído de uma visão inicial fragmentada sobre poluição para uma visão sistêmica.
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The nucleon anapole form factor in chiral perturbation theory to sub-leading order
(2000) Maekawa, Claudio Masumi; Veiga, Jaime Sandro; Kolck, Ubirajara Van
The anapole form factor of the nucleon is calculated in chiral perturbation theory to sub-leading order. This is the lowest order in which the isovector anapole form factor does not vanish. The anapole moment depends on counterterms that reflect short-range dynamics, but the momentum dependence of the form factor is determined by pion loops in terms of parameters that could in principle be fixed from other processes. If these parameters are assumed to have natural size, the sub-leading corrections do not exceed ;30% at momentum Q;300 MeV.
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The anapole form factor of the nucleon
(2000) Maekawa, Claudio Masumi; Kolck, Ubirajara Van
The anapole form factor of the nucleon is calculated in chiral perturbation theory in leading order. To this order, the form factor originates from the pion cloud, and is proportional to the non-derivative parity-violating pion–nucleon coupling. The momentum dependence of the form factor – and in particular, its radius – is completely determined by the pion mass.
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Nucleon-Nucleon interaction: central potential and pion-production
(2000) Maekawa, Claudio Masumi; Pupin, Joel Cesar; Robilotta, Manoel Roberto
We show that the tail of the chiral two-pion exchange nucleon-nucleon potential is proportional to the pion-nucleon (pN) scalar form factor and discuss how it can be translated into effective scalar meson interactions. We then construct a kernel for the process NN!pNN, due to the exchange of two pions, which may be used in either three-body forces or pion production in NN scattering. Our final expression involves a partial cancellation among three terms, due to chiral symmetry, but the net result is still important. We also find that, at large internucleon distances, the kernel has the same spatial dependence as the central NN potential and we produce expressions relating these processes directly.
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Algumas possibilidades de utilização dos princípios de sistemas de Forrester em tópicos de física, através da ferramenta de modelagem quantitativa STELLA
(2000) Santos, Arion de Castro Kurtz dos; Yoshihisa, Cho; Araújo, Ives Solano; Gonçalves, Geovane Pedra
Forrester, em 1971, lançou seus Princípios de Sistemas consolidando a utilização do computador na área de gerenciamento. Desde então, alguns pesquisadores têm tentado, com algum sucesso, trazer os Princípios de Sistemas para áreas como, por exemplo, Ecologia, Biologia, Química e Física. Esse artigo, baseado em material instrucional desenvolvido pelo projeto PROFECOMP-FURG e aplicado extensivamente a professores e alunos de nível universitário básico, propõe um possível modo de utilização dos Princípios de Sistemas de Forrester em alguns conteúdos de Física.
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Um experimento de modelagem dinâmica semiquantitativa com a utilização da técnica dos hexágonos
(2000) Santos, Arion de Castro Kurtz dos; Sampaio, Fábio Ferrentini; Ferracioli, Laércio
O presente artigo relata um pequeno experimento realizado com alunos de Mestrado sobre o desenvolvimento de modelos semiquantitativos utilizando o ambiente de modelagem VISQ e posteriormente STELLA. A concepção, elaboração e representação dos modelos incluiu uma fase conceitual utilizando a técnica dos hexágonos (ídones – combinação de idéia e ícone). Um modelo clássico, para elos não lineares acoplados, apresentado na obra de Forrester, foi utilizado como um parâmetro para definir a atividade e como um critério de validação. Os resultados sugerem que parece ser recomendável, antes de partir direto para o computador, passar por uma fase de desenvolvimento do modelo conceitual com ídones. Embora tenha sido muito simples o modelo desenvolvido com STELLA, quando comparado ao padrão de Forrester, os resultados mostraram que os estudantes foram capazes de construir um diagrama de fluxo tendo como base o modelo previamente desenvolvido em VISQ.
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Remarks on the duffin-kemmer-petiau theory and gauge invariance
(2000) Lunardi, José Tadeu Teles; Escobar, Bruto Max Pimentel; Teixeira, Randall Guedes; Salvador, Juan Segundo Valverde
Two problems relative to the electromagnetic coupling of Duffin-Kemmer-Petiau (DKP) theory are discussed: the presence of an anomalous term in the Hamiltonian form of the theory and the apparent difference between the Interaction terms in DKP and Klein-Gordon (KG) Lagrangians. For this, we first discuss the behavior of DKP field and its physical components under gauge transformations. From this analysis, we can show that these problems simply do not exist if one correctly analyses the physical components of DKP field.
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A modelagem computacional como uma possível estratégia para a educação ambiental fundamental
(2001) Santos, Arion de Castro Kurtz dos; Russo, Dulce Helena Souza; Araújo, Ives Solano; Almeida, Maria Teresa de Albernaz
O artigo apresenta alguns desenvolvimentos recentes associados ao projeto PROFECOMP – Desenvolvimento e Uso de Ferramentas Computacionais para o Aprendizado Exploratório de Ciências da FURG que em seus aspectos relativos ao tratamento de questões de Educação Ambiental é Sub-Projeto de um projeto maior específico do curso de Mestrado em Educação Ambiental. Dentre os resultados de pesquisa incluímos no presente artigo o desenvolvimento de um Autômato Celular, para o trabalho com o raciocínio em nível de objetos, e resultados de utilização do programa VISQ, para modelagem semiquantitativa, em particular uma utilização inovadora da ferramenta para a elicitação da representação do especialista e conseqüente construção de um instrumento fidedigno, bem como algumas recomendações para utilização com alunos do ensino fundamental.
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Aspects of habitat use patterns of humpback whales in the Abrolhos bank, Brazil, breeding ground
(2001) Martins, Cristiane Cavalcante Albuquerque; Morete, Maria Emilia; Coitinho, Márcia Helena Engel; Freitas, Ana Cristina; Secchi, Eduardo Resende; Kinas, Paul Gerhard
The Abrolhos Bank (off the State of Bahia, northeastern Brazil) is the most important breeding and calving ground for humpback whales, Megaptera novaeangliae, in the western South Atlantic. The area is shallow with a mean depth of 30m and a group of five islands (the Abrolhos Archipelago) is located in the northern portion of the Bank. Data collected from 1992 to 1998 were analysed to identify possible different habitat use patterns by different humpback whale group types. An analysis of variance found differences in the mean water depths where different group types were recorded: single whales, 18.9m (se = 0.505); pairs, 18.6m (se = 0.386); competitive groups, 19.1m (se = 0.573); mother-calf pairs, 15.8m (se = 0.373); mother-calf-principal escort, 14.9m (se = 0.489); and competitive group with mother-calf pair, 16.4m (se = 0.889). With the exception of competitive groups, those containing calves (mother-calf alone or mother-calf-principal escort) occurred in significantly shallower water than non-calf groups (Tukey test, p<0.05). In addition, groups containing calves were found significantly more often nearer the Archipelago (within 4 nautical miles) than other groups (two-sample Kolmogorov-Smirnov test, D = 0.139; 2 = 18.516, p<0.05). Accordingly, a spatially stratified management scheme is recommended in order to protect mother-calf pairs from possible harassment by whale watching operations in the area.
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Photo-identification of humpback whales, Megaptera novaeangliae, off the Antarctic peninsula: 1997/98 to 1999/2000
(2001) Dalla Rosa, Luciano; Secchi, Eduardo Resende; Kinas, Paul Gerhard; Santos, Marcos César de Oliveira; Martins, Marcio; Zerbini, Alexandre Novaes; Bethlem, Cláudia
During three Summer seasons (1997/98-1999/00), photographic sampling of humpback whales was conducted by Projeto Baleia/Brazilian Antartic Programme in Waters of the Antartic Peninsula. Whales photographed totalled: 63 (1997/1998), 70 (1998/1999) and 21 (1999/2000). Of these, 74,6% (n=47), 87,1% (n=61) and 100% (n=21), respectively, were represented by photographs categorised as quality 1 (excellent) or 2 (moderate). Inter-annual comparisons showed two matches: a whale photographed on 27 January 1998 in the Gerlache Strait was resighted on 11 January 1999 in the same region; the second on 3 February 1998 in the Gerlache Strait was resighted on 25 January 1999 at almost the same coordinates. These matches indicate that humpback whales may show fidelity to feeding grounds off the Antartic Peninsula. Intra-annual comparisons showed two matches: a whale photographed on 22 January 1998 close to the King George Island and another on 27 January 1998 in the Bismarck Strait were resighted together on 7 March 1998 in the Gerlache Strait. Average índices of fluke colouration obtained for 1997/1998 and 1998/1999 were 2.39 (n=44) and 2.60 (n=53), respectively. Total average índex, including photographs from the three period, resulted in 2.54 (n=116). All values are significantly different from those obtained by Rosenbaum ET AL. (1995) for western and eastern Australia (p<0.001) and similar to that found for Colombia (p>0.05) (non-parametric test of Kolmogorov-Smirnov). These results reinforce the view that humpback whales feeding in the western side of the Antartic Peninsula probably originate from eastern South Pacific breeding grounds.
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A first estimate of franciscana (Pontoporia blainvillei) abundance off southern Brazil
(2001) Secchi, Eduardo Resende; Ott, Paulo Henrique; Crespo, Enrique; Kinas, Paul Gerhard; Pedraza, Susana; Bordino, Pablo
The franciscana, Pontoporia blainvillei, is endemic to the western South Atlantic Ocean and is perhaps one of the most threatened small cetacean species in this region. This paper presents a first abundance estimate for the coastal waters of Rio Grande do Sul State (southern Brazil) and Uruguay. In March 1996, an aerial survey was conducted along the Rio Grande do Sul State coast. Thirty-four franciscanas (29 groups) were recorded leading to a mean density estimate of 0.657 individuals/km2 (95% CI: 0.516 to 0.836) for the study area (435km2) after applying a correction factor for submerged dolphins. This corresponds to an estimated abundance of 286 franciscanas (95% CI: 225 to 364). The study area represents only 0.7% of the suggested distribution of the stock. The paper discusses possible management implications of this study in the light of reported incidental mortality estimates for this region. Further surveys covering a larger area are recommended in order to obtain more reliable abundance estimates for the stock.
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Resultados parciais de um estudo com alunos do ensino fundamental de Rio Grande, sobre problemas ambientais, tendo como base a modelagem semiquantitativa
(2001) Almeida, Maria Teresa de Albernaz; Santos, Arion de Castro Kurtz dos
O desenvolvimento de modelos semiquantitativos, através do programa VISQ, que têm como base a Dinâmica de Sistemas, permitiu, com a utilização de técnicas e ferramentas de elicitação de conhecimento, o desenvolvimento de modelos sobre problemas ambientais. Com um número adequado de variáveis, obtidas em trabalhos anteriores realizados na região, utilizando o conhecimento do especialista, foram desenvolvidos dois modelos: um sobre a questão da contaminação por lixo e outro por esgoto. Os modelos foram validados e após utilizados para a construção de um questionário que pretendeu traçar o perfil de conhecimento de 120 alunos do ensino fundamental. O presente trabalho apresenta resultados parciais sobre um dos modelos desenvolvidos, o instrumento de coleta de dados e o padrão de respostas dos estudantes.
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Ultraviolet line spectra of metal-poor star-forming galaxies
(2001) Leitherer, Claus; Leão, Joao Rodrigo Souza; Heckman, Timothy Martin; Lennon, Daniel J.; Pettini, Max; Robert, Carmelle
We present synthetic ultraviolet spectra of metal-poor star-forming galaxies that were calculated with the Starburst99 package. A new spectral library was generated from Hubble Space Telescope observations of O stars in the Large and Small Magellanic Clouds. The corresponding mean metallicity of the synthetic spectra is approximately The spectra have a resolution of 1 and cover the spectral 14 Z_. A. range 1200È1600 A. . A set of model spectra was calculated for a standard initial mass function and star formation history and is compared to synthetic spectra at solar metallicity. We Ðnd that the spectral lines are generally weaker at lower metallicity, as expected from the lower elemental abundances. Stellar wind lines, however, show a more complex behavior : the metallicity dependence of the ionization balance can be important in trace ions, like N4` and Si3`. Therefore, the strength of N V j1240 and Si IV j1400 does not scale monotonically with metallicity. We compare our new models to ultraviolet spectra of NGC 5253 and MS 1512-cB58, two star-forming galaxies with one-fourth solar metallicity at low and high redshifts, respectively. The new library provides signiÐcantly better Ðts to the observations than earlier models using the Z library. We discuss the potential of utilizing stellar photospheric and _ wind lines to estimate the chemical composition of star-forming galaxies. The new metal-poor synthetic spectra are available via the Starburst99 Web site.
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Parity-violating photoproduction of pion on the delta ressonance
(2001) Zhu, Shi-Lin; Maekawa, Claudio Masumi; Holstein, Barry; Ramsey-Musolf, Michael
We analyze the degree to which parity-violating ~PV! electroexcitation of the D(1232) resonance may be used to extract the weak neutral axial vector transition form factors. We find that the axial vector electroweak radiative corrections are large and theoretically uncertain, thereby modifying the nominal interpretation of the PV asymmetry in terms of the weak neutral form factors. We also show that, in contrast with the situation for elastic electron scattering, the axial N!D PV asymmetry does not vanish at the photon point as a consequence of a new term entering the radiative corrections. We argue that an experimental determination of these radiative corrections would be of interest for hadron structure theory, possibly shedding light on the violation of Hara’s theorem in weak, radiative hyperon decays.