O instrumento “CoRe” como atividade didática para acessar o conhecimento pedagógico do conteúdo de licenciandos

Este estudo situa-se no campo de formação de professores e utiliza o conceito de PCK - conhecimento pedagógico do conteúdo - como referencial teórico. Nossa pesquisa busca acessar indícios do PCK de um grupo de licenciandos que cursam uma disciplina do curso de licenciatura do Instituto de Química da Universidade de São Paulo. Investigou-se o PCK desses licenciandos a partir da discussão sobre o tema natureza da matéria realizada durante a elaboração do instrumento CoRe - representação de conteúdo (LOUGHRAN; MULHALL; BERRY, 2004). Efetuou-se a análise de conteúdo dos registros em áudio e vídeo, agrupando-se as ideias centrais em categorias descritas na literatura, a partir do modelo de PCK de Rollnick et al. (2008). Os resultados indicam que o processo de elaboração do CoRe foi capaz de revelar o PCK dos licenciandos em construção através da transformação dos conhecimentos sobre os estudantes, a pedagogia e sobre o contexto (SHUMAN,1986)

Coexistence of halloysite and kaolinite: a study on the genesis of kaolin clays of Campo Alegre Basin, Santa Catarina State, Brazil

Kaolin at Campo Alegre Basin, Santa Catarina State, Brazilwas formed from alteration of volcanic acid rocks. Halloysite clays dominate the clay fraction of the matrix of the kaolin body, whereas a poorly crystalline kaolinite is abundant in veins. Some primary blocky structures have high amounts of illite, in one mine, but in general, only low contents of illite-smectite, illite, chlorite-vermiculite, vermiculite and quartz were identified in the clay fraction of the samples. Toward the top of the mines, hematite and lepidocrocite appear in horizontal red and ochre colored levels and the amount of kaolinite increases compared to halloysite. The vertical zoning of alteration levels, the changes in mineralogy, the positive correlation between depth and Cation Exchange Capacity of the clays, the preservation of different types of rock textures in the kaolin bodies, the dominant tube morphology of the halloysite clays indicate a supergene genesis for the deposits. Criteria to distinguish between supergene and hypogene kaolin are discussed. Transmission Electron Microscopy of the cross sections of halloysite tubes showed polygonal forms that are ascribed to be transitional between kaolinite and halloysite. It is proposed that some of the kaolinite of these deposits be inherited from the dehydration of halloysite tubes

Exact Solutions of the Klein-Gordon Equation in the Presence of a Dyon, Magnetic Flux and Scalar Potential in the Specetime of Gravitational Defects

In this paper we analyse the relativistic quantum motion of a charged spin-0 particle in the presence of a dyon, Aharonov-Bohm magnetic field and scalar potential, in the spacetimes produced by an idealized cosmic string and global monopole. In order to develop this analysis, we assume that the dyon and the Aharonov-Bohm magnetic field are superposed to both gravitational defects. Two distinct configurations for the scalar potential, $S(r)$, are considered: $i)$ the potential proportional to the inverse of the radial distance, i.e., $S\propto1/r$, and $ii)$ the potential proportional to this distance, i.e., $S\propto r$. For both cases the center of the potentials coincide with the dyon's position. In the case of the cosmic string the Aharonov-Bohm magnetic field is considered along the defect, and for the global monopole this magnetic field pierces the defect. The energy spectra are computed for both cases and explicitly shown their dependence on the electrostatic and scalar coupling constants. Also we analyse scattering states of the Klein-Gordon equations, and show how the phase shifts depend on the geometry of the spacetime and on the coupling constants parameter.Comment: To be published in CQG. Minor comments adde

Desempenho do consórcio entre repolho e rabanete com pré-cultivo de crotalária, sob manejo orgânico.

Foram conduzidos dois experimentos no Sistema Integrado de Produção Agroecológica, em Seropédica, (RJ), durante dois anos consecutivos. O objetivo foi avaliar o desempenho do consórcio entre as culturas de repolho e rabanete com pré-cultivo de crotalária, sob manejo orgânico. Usou-se delineamento experimental de blocos ao acaso com sete repetições, em parcelas subdivididas, representando um fatorial 2 x 3, sendo o primeiro fator o pré-cultivo, com Crotalaria juncea e pousio (vegetação espontânea); e o segundo fator o sistema de cultivo (consórcio entre repolho e rabanete e os respectivos monocultivos). Não houve diferença significativa no tocante à produtividade do repolho ou rabanete, entre C. juncea e pousio, independentemente do tipo de manejo (monocultivos ou consórcio). O desenvolvimento do repolho não foi influenciado pela presença do rabanete, no consórcio entre essas espécies sob cultivo orgânico. O rabanete sob consórcio apresentou redução no diâmetro médio, massa média e produtividade de raízes, sem, contudo,desqualificar o padrão comercial das raízes colhidas. Considerando a média dos dois anos experimentais, o IEA atingiu 1,59, o que indicou a viabilidade do consórcio, otimizando práticas culturais, incluindo adubação,capina e irrigação

Lattice model of gas condensation within nanopores

We explore the thermodynamic behavior of gases adsorbed within a nanopore. The theoretical description employs a simple lattice gas model, with two species of site, expected to describe various regimes of adsorption and condensation behavior. The model includes four hypothetical phases: a cylindrical shell phase (S), in which the sites close to the cylindrical wall are occupied, an axial phase (A), in which sites along the cylinder's axis are occupied, a full phase (F), in which all sites are occupied, and an empty phase (E). We obtain exact results at T=0 for the phase behavior, which is a function of the interactions present in any specific problem. We obtain the corresponding results at finite T from mean field theory. Finally, we examine the model's predicted phase behavior of some real gases adsorbed in nanopores

On the running coupling constant in QCD

We try to review the main current ideas and points of view on the running coupling constant in QCD. We begin by recalling briefly the classic analysis based on the Renormalization Group with some emphasis on the exact solutions of the RG equation for a given number of loops, in comparison with the usual approximate expressions. We give particular attention to the problem of eliminating the unphysical Landau singularities, and of defining a coupling that remains significant at the infrared scales. We consider various proposals of couplings directly related to the quark-antiquark potential or to other physical quantities (effective charges) and discuss optimization in the choice of the scale parameter and of the RS. Our main focus is, however, on dispersive methods, their application, their relation with non-perturbative effects. We try also to summarize the main results obtained by Lattice simulations in various MOM schemes. We conclude briefly recalling the traditional comparison with the experimental data.Comment: 75 pages, 8 figures. Corrected typos, added references, replaced 1 figure. Accepted for publication in Progress in Particle and Nuclear Physic

Produção de biossurfactante por linhagens de pseudomonas isoladas do solo rizosférico no Semiárido da Bahia, Brasil

The aim of this study was to select biosurfactant-producing bacterial strains from soils of plants in the semi-arid region of the state of Bahia, Brazil. The mineral salt medium (MSM) was used as base medium, changes being made in the glucose concentration, temperature, and pH during the optimization process. Two biosurfactant-producing bacterial strains were isolated from the soil of Actinocephalus sp. and belonged to the genus Pseudomonas. The emulsification indexes of these strains rose until 58%. They reduced surface and interfacial tensions of culture medium and crude oil to less than 33 mN/m and 3 mN/m, respectively. This study represented an unprecedented discovery of surfactant activity of the bacterial strains isolated from rhizospheric soils of plants from Northeast Brazilian semi-arid region.O objetivo deste estudo foi selecionar linhagens bacterianas produtoras de biossurfactante do solo rizosférico de plantas na região semiárida do estado da Bahia, Brasil. O meio salino mineral (MSM) foi usado como meio base, sendo realizadas mudanças na concentração de glicose, temperatura e pH durante o processo de otimização. Duas linhagens produtoras de biossurfactante foram isoladas do solo rizosférico de Actinocephalus sp. e pertencem ao gênero Pseudomonas. Os índices de emulsificação destas linhagens aumentaram até 58%. As linhagens de Pseudomonas reduziram as tensões superficial e interfacial do meio de cultura e do óleo cru para menos de 33 mN/m e 3 mN/m, respectivamente. Este estudo representou uma descoberta inédita da atividade surfactante de linhagens bacterianas isoladas de solo rizosférico de plantas da região semiárida, no Nordeste Brasileiro

Automatic diagnosis of the 12-lead ECG using a deep neural network

The role of automatic electrocardiogram (ECG) analysis in clinical practice is limited by the accuracy of existing models. Deep Neural Networks (DNNs) are models composed of stacked transformations that learn tasks by examples. This technology has recently achieved striking success in a variety of task and there are great expectations on how it might improve clinical practice. Here we present a DNN model trained in a dataset with more than 2 million labeled exams analyzed by the Telehealth Network of Minas Gerais and collected under the scope of the CODE (Clinical Outcomes in Digital Electrocardiology) study. The DNN outperform cardiology resident medical doctors in recognizing 6 types of abnormalities in 12-lead ECG recordings, with F1 scores above 80% and specificity over 99%. These results indicate ECG analysis based on DNNs, previously studied in a single-lead setup, generalizes well to 12-lead exams, taking the technology closer to the standard clinical practice

Infrared Properties of QCD from Dyson-Schwinger equations

I review recent results on the infrared properties of QCD from Dyson-Schwinger equations. The topics include infrared exponents of one-particle irreducible Green's functions, the fixed point behaviour of the running coupling at zero momentum, the pattern of dynamical quark mass generation and properties of light mesons.Comment: 47 pages, 19 figures, Topical Review to be published in J.Phys.G, v2: typos corrected and some references adde