948 resultados para Classes de palavras
Resumo:
Participaram do estudo 180 adolescentes (90M e 90F) com idades variando entre 15 e 17 anos, alunos do ensino médio, pertencentes a diferentes classes sociais. Foram comparados gêneros e classes sócio-econômicas a respeito dos valores de beleza e de inteligência que adolescentes atribuem a si próprios e, numa situação hipotética e de forma mutuamente exclusiva, qual desses atributos foram mais valorizados para si mesmos e para possíveis parceiros. Os resultados mostraram que os rapazes de classe alta atribuíram-se maiores notas de inteligência. Adolescentes de ambos sexos pertencentes à classe baixa gostariam de possuir um maior nível de inteligência em detrimento da beleza, enquanto que adolescentes de classe alta preferem o equilíbrio entre beleza e inteligência. As moças valorizam mais a inteligência em seus parceiros que os rapazes, os quais valorizam mais a beleza em suas parceiras.
Resumo:
OBJETIVO: Avaliar e comparar a prevalência de fatores de riscos cardiovasculares em adolescentes escolares de diferentes classes econômicas. MÉTODOS: Foram avaliados 1.021 adolescentes. Os indivíduos foram pesados e tiveram sua altura e circunferência abdominal medidos, além da sua pressão arterial aferida. A prática de atividade física e condição socioeconômica foram relatadas. Os resultados foram avaliados pela utilização da frequência das variáveis e pelo teste do qui-quadrado. RESULTADOS: Observou-se menor prevalência de sedentarismo (p < 0,001) e maiores prevalências de obesidade abdominal (p = 0,038) e de sobrepeso (p = 0,010) entre adolescentes da classe econômica alta. Não houve diferença de prevalência de pressão arterial elevada entre adolescentes da classe econômica baixa e alta. Quando os fatores de risco cardiovasculares foram agregados, a prevalência também foi maior na classe econômica alta para um ou dois fatores de risco. CONCLUSÃO: Com exceção do sedentarismo e da pressão arterial elevada, a prevalência de fatores de risco para doenças cardiovasculares foi maior na classe econômica alta.
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In this work we consider the effect of a spatially dependent mass over the solution of the Klein-Gordon equation in 1 + 1 dimensions, particularly the case of inversely linear scalar potential, which usually presents problems of divergence of the ground-state wave function at the origin, and possible nonexistence of the even-parity wave functions. Here we study this problem, showing that for a certain dependence of the mass with respect to the coordinate, this problem disappears. (c) 2006 Elsevier B.V. All rights reserved.
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This paper deals with the classes S-3(omega, beta, b) of strong distribution functions defined on the interval [beta(2)/b, b], 0 < beta < b <= infinity, where 2 omega epsilon Z. The classification is such that the distribution function psi epsilon S-3(omega, beta, b) has a (reciprocal) symmetry, depending on omega, about the point beta. We consider properties of the L-orthogonal polynomials associated with psi epsilon S-3(omega, beta, b). Through linear combination of these polynomials we relate them to the L-orthogonal polynomials associated with some omega epsilon S-3(1/2, beta, b). (c) 2004 Elsevier B.V. All rights reserved.
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The training and the application of a neural network system for the prediction of occurrences of secondary metabolites belonging to diverse chemical classes in the Asteraceae is described. From a database containing about 604 genera and 28,000 occurrences of secondary metabolites in the plant family, information was collected encompassing nine chemical classes and their respective occurrences for training of a multi-layer net using the back-propagation algorithm. The net supplied as output the presence or absence of the chemical classes as well as the number of compounds isolated from each taxon. The results provided by the net from the presence or absence of a chemical class showed a 89% hit rate; by excluding triterpenes from the analysis, only 5% of the genera studied exhibited errors greater than 10%. Copyright (C) 2004 John Wiley Sons, Ltd.
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In this work the influence of two different iron sources, Fe(NO3)(3) and complexed ferrioxalate (FeOx), on the degradation efficiency of 4-chlorophenol (4CP), malachite green, formaldehyde, dichloroacetic acid (DCA) and the commercial products of the herbicides diuron and tebuthiuron was studied. The oxidation of 4CP, DCA, diuron and tebuthiuron shows a strong dependence on the iron source. While the 4CP degradation is favored by the use of Fe(NO3)(3), the degradation of DCA and the herbicides diuron and tebuthiuron is most efficient when ferrioxalate is used. on the other hand, the degradation of malachite green and formaldehyde is not very influenced by the iron source showing only a slight improvement when ferrioxalate is used. In the case of formaldehyde, DCA, diuron and tebuthiuron, despite of the additional carbon introduced by the use of ferrioxalate, higher mineralization percentages were observed, confirming the beneficial effect of ferrioxalate on the degradation of these compounds. The degradation of tebuthiuron was studied in detail using a shallow pond type solar flow reactor of 4.5 L capacity and 4.5 cm solution depth. Solar irradiation of tebuthiuron at a flow rate of 9 L h(-1), in the presence of 10.0 mmol L-1 H2O2 and 1.0 mmol L-1 ferrioxalate resulted in complete conversion of this herbicide and 70% total organic carbon removal. (c) 2005 Elsevier Ltd. All rights reserved.
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In this work we discuss some exactly solvable Klein-Gordon equations. We basically discuss the existence of classes of potentials with different nonrelativistic limits, but which shares the intermediate effective Schroedinger differential equation. We comment about the possible use of relativistic exact solutions as approximations for nonrelativistic inexact potentials. (c) 2005 Elsevier B.V. All rights reserved.
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Previous analyses of mitochondrial (mt)DNA and allozymes covering the range of the Iberian endemic golden-striped salamander, Chioglossa lusitanica, suggested a Pleistocene split of the historical species distribution into two population units (north and south of the Mondego river), postglacial expansion into the northernmost extant range, and secondary contact with neutral diffusion of genes close to the Mondego river. We extended analysis of molecular variation over the species range using seven microsatellite loci and the nuclear P-fibrinogen intron 7 (beta-fibint7). Both microsatellites and beta-fibint7 showed moderate to high levels of population structure, concordant with patterns detected with mtDNA and allozymes; and a general pattern of isolation-by-distance, contrasting the marked differentiation of two population groups suggested by mtDNA and allozymes. Bayesian multilocus analyses showed contrasting results as populations north and south of the Douro river were clearly differentiated based on microsatellites, whereas allozymes revealed differentiation north and south of the Mondego river. Additionally, decreased microsatellite variability in the north supported the hypothesis of postglacial colonization of this region. The well-documented evolutionary history of C. lusitanica, provides an excellent framework within which the advantages and limitations of different classes of markers can be evaluated in defining patterns of population substructure and inferring evolutionary processes across distinct spatio-temporal scales. The present study serves as a cautionary note for investigations that rely on a single type of molecular marker, especially when the organism under study exhibits a widespread distribution and complex natural history. (C) 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95, 371-387.
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The construction of two classes of exact solutions for the most general time-dependent Dirac Hamiltonian in 1+1 dimensions was discussed. The extension of solutions by introduction of a time-dependent mass was elaborated. The possibility of existence of a generalized Lewis-Riesenfeld invariant connected with such solutions was also analyzed.
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In this work we solve exactly a class of three-body propagators for the most general quadratic interactions in the coordinates, for arbitrary masses and couplings. This is done both for the constant as the time-dependent couplings and masses, by using the Feynman path integral formalism. Finally, the energy spectrum and the eigenfunctions are recovered from the propagators. © 2005 Elsevier Inc. All rights reserved.
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The great diversity of materials that characterizes the urban environment determines a structure of mixed classes in a classification of multiespectral images. In that sense, it is important to define an appropriate classification system using a non parametric classifier, that allows incorporating non spectral (such as texture) data to the process. They also allow analyzing the uncertainty associated to each class from the output alues of the network calculated in relation to each class. Considering these properties, an experiment was carried out. This experiment consisted in the application of an Artificial Neural Network aiming at the classification of the urban land cover of Presidente Prudente and the analysis of the uncertainty in the representation of the mapped thematic classes. The results showed that it is possible to discriminate the variations in the urban land cover through the application of an Artificial Neural Network. It was also possible to visualize the spatial variation of the uncertainty in the attribution of classes of urban land cover from the generated representations. The class characterized by a defined pattern as intermediary related to the impermeability of the urban soil presented larger ambiguity degree and, therefore, larger mixture.
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The primary objective of this study is to evaluate by means of remote sensing and GIS, the landscape evolution around the Jaguari and Jacareí River Dam, located in the eastern section of the State of São Paulo, Brazil. For this purpose we used LANDSAT 5/YM and CBERS-2/CCD images from 1984/1985 and 2006, respectively, considering the following classes of land use: forest, cultivated forest, agriculture, urban areas and water bodies. The two selected dates reflect important changes in the region such as the installation of the dam and subsequent urbanization of parts of its margins and the enlargement of the Fernão Dias Federal Highway, which contributed to an increase of areas of anthropic activities in the studied region. The results also indicate an increase in areas covered by native and planted forests, thus confirming a similar trend in other areas of the State of São Paulo.