621 research outputs found

    Portfólios e a avaliação do conhecimento sobre natureza da ciência em um contexto histórico

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    Analisamos os portfólios elaborados por uma licencianda durante sua participação em um curso de formação inicial de professores de química, cuja temática central era Natureza da Ciência (NC). Avaliamos o conhecimento sobre NC da licencianda a partir de suas reflexões sobre sua vivência em um estudo de caso envolvendo uma controvérsia sobre um fato histórico (julgamento da outorga do prêmio Nobel de Química de 1918 a Fritz Haber pela síntese da amônia em escala industrial). A análise aponta que o caso histórico contribuiu para a compreensão de características sobre ciência, e o portfólio permitiu uma avaliação contextualizada e detalhada desses conhecimentos

    Evolução Cinemática das Porções Internas do Cinturão Dom Feliciano, Região de Piratini, RS

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    Dois episódios cinemáticos afetando rochas da associação de arco magmático precoce (AAM I) do Cinturão Dom Feliciano foram reconhecidos na área de Piratini: um fluxo tectônico mais antigo de orientação NW-SE seguido por um fluxo de orientação NE-SW. O fluxo tectônico precoce transversal ao alongamento do cinturão é registrado por zonas de cisalhamento sub-horizontais e subverticais. O fluxo tangencial é caracterizado por deformação de alta temperatura no estado sólido afetando gnaisses dioríticos da associação de arco magmático precoce. Estruturas de escala microscópica dessa deformação foram em grande parte obliteradas por migmatização e/ou injeções graníticas sin- a tardi-tectônicas. Os padrões de fluxo, tanto o de deformação no estado sólido quanto o magmático, sugerem movimento do bloco superior para NW. A zona de cisalhamento transcorrente NW-SE é caracterizada por uma movimentação levogira sob condições metamórficas da fácies anfibolito afetando gnaisses granodioríticos da AAM I. A trama resultante foi parcialmente rearranjada por crescimento estático da maioria dos minerais que foram subsequentemente recristalizados durante reativação dessas zonas de cisalhamento sob condições decrescentes de temperatura. A deformação tardia é caracterizada por fluxo paralelo ao orógeno (NE-SW) em (i) uma zona de cisalhamento transcorrente de escala regional associado com um expressivo magmatismo sincinemático, e (ii) ao longo de diversas zonas de cisalhamento discretas e subordinadas, retrabalhando as rochas ígneas pré-existente. Indicadores cinemáticos consistentes, nas zonas de cisalhamento discretas de pequena escala, sugerem sentido de cisalhamento dextrogiro. Essa deformação desenvolvida sob condições metamórficas retrogressivas da fácies anfibolito superior a xisto verde inferior foi provavelmente controlada pelo resfriamento dos granitoides sincinemáticos

    Green manure legumes affect seasonal soil and leaf CO2 exchange rates in an olive rainfed orchard

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    Management methods that decrease requirement for agricultural chemicals are needed to reduce adverse environmental impacts. Moreover, they can play an important role in atmospheric C02 emission and fixation. We propose green manure legumes to reduce erosion, soil compaction and nitrate pollution, to improve biodiversity, soil carbon sink and fertility, to save fossil fuels and to increase yield and the nutritional value of food products. The research was carried out near Mirandela, Northeast Portugal, on a 15- year commercial olive orchard (Olea europaea L. cv. Cobrançosa), grown under rainfed conditions

    Repeatability and reproducibility of multiparametric magnetic resonance imaging of the liver

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    As the burden of liver disease reaches epidemic levels, there is a high unmet medical need to develop robust, accurate and reproducible non-invasive methods to quantify liver tissue characteristics for use in clinical development and ultimately in clinical practice. This prospective cross-sectional study systematically examines the repeatability and reproducibility of iron-corrected T1 (cT1), T2*, and hepatic proton density fat fraction (PDFF) quantification with multiparametric MRI across different field strengths, scanner manufacturers and models. 61 adult participants with mixed liver disease aetiology and those without any history of liver disease underwent multiparametric MRI on combinations of 5 scanner models from two manufacturers (Siemens and Philips) at different field strengths (1.5T and 3T). We report high repeatability and reproducibility across different field strengths, manufacturers, and scanner models in standardized cT1 (repeatability CoV: 1.7%, bias -7.5ms, 95% LoA of -53.6 ms to 38.5 ms; reproducibility CoV 3.3%, bias 6.5 ms, 95% LoA of -76.3 to 89.2 ms) and T2* (repeatability CoV: 5.5%, bias -0.18 ms, 95% LoA -5.41 to 5.05 ms; reproducibility CoV 6.6%, bias -1.7 ms, 95% LoA -6.61 to 3.15 ms) in human measurements. PDFF repeatability (0.8%) and reproducibility (0.75%) coefficients showed high precision of this metric. Similar precision was observed in phantom measurements. Inspection of the ICC model indicated that most of the variance in cT1 could be accounted for by study participants (ICC = 0.91), with minimal contribution from technical differences. We demonstrate that multiparametric MRI is a non-invasive, repeatable and reproducible method for quantifying liver tissue characteristics across manufacturers (Philips and Siemens) and field strengths (1.5T and 3T)

    Fitting the integrated Spectral Energy Distributions of Galaxies

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    Fitting the spectral energy distributions (SEDs) of galaxies is an almost universally used technique that has matured significantly in the last decade. Model predictions and fitting procedures have improved significantly over this time, attempting to keep up with the vastly increased volume and quality of available data. We review here the field of SED fitting, describing the modelling of ultraviolet to infrared galaxy SEDs, the creation of multiwavelength data sets, and the methods used to fit model SEDs to observed galaxy data sets. We touch upon the achievements and challenges in the major ingredients of SED fitting, with a special emphasis on describing the interplay between the quality of the available data, the quality of the available models, and the best fitting technique to use in order to obtain a realistic measurement as well as realistic uncertainties. We conclude that SED fitting can be used effectively to derive a range of physical properties of galaxies, such as redshift, stellar masses, star formation rates, dust masses, and metallicities, with care taken not to over-interpret the available data. Yet there still exist many issues such as estimating the age of the oldest stars in a galaxy, finer details ofdust properties and dust-star geometry, and the influences of poorly understood, luminous stellar types and phases. The challenge for the coming years will be to improve both the models and the observational data sets to resolve these uncertainties. The present review will be made available on an interactive, moderated web page (sedfitting.org), where the community can access and change the text. The intention is to expand the text and keep it up to date over the coming years.Comment: 54 pages, 26 figures, Accepted for publication in Astrophysics & Space Scienc

    Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment

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    This paper describes an analysis of the angular distribution of W->enu and W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with the ATLAS detector at the LHC in 2010, corresponding to an integrated luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and the missing transverse energy, the W decay angular distribution projected onto the transverse plane is obtained and analysed in terms of helicity fractions f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw > 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour, are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017 +/- 0.030, where the first uncertainties are statistical, and the second include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables, revised author list, matches European Journal of Physics C versio
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