21 research outputs found

    The Compton scattering of X-rays in the diagnosis of breast neoplasia

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    Neste trabalho foram realizadas medidas de espalhamento el√°stico e inel√°stico em tecidos mam√°rios normais e neopl√°sicos (benignos e malignos) usando uma energia de 17,44 keV (radia√ß√£o K? ¬¨- Mo) e um √Ęngulo de espalhamento de 90¬ļ (x = 0,99√Ö-1) com o objetivo de determinar as densidades eletr√īnicas (?e), n√ļmero at√īmico efetivo (Zef) e largura a meia altura (LMA) do pico de espalhamento inel√°stico destes tecidos. Tamb√©m foram estudadas por meio de simula√ß√Ķes computacionais imagens obtidas por t√©cnica de tomografia de espalhamento Compton. As metodologias experimentais foram verificadas atrav√©s da an√°lise de materiais de refer√™ncia. Os valores de densidades eletr√īnicas e n√ļmeros at√īmicos efetivos obtidos foram comparados com dados experimentais e te√≥ricos previamente publicados, mostrando uma boa concord√Ęncia com estes (diferen√ßas menores que 5%). Os valores de LMA obtidos indicam a possibilidade de uso deste par√Ęmetro para obter informa√ß√£o sobre composi√ß√£o dos tecidos e se mostraram correlacionados com os valores de Zef. Os resultados tamb√©m mostram que existem diferen√ßas de ?e, Zef e LMA entre os grupos de tecidos, as quais est√£o associadas √† composi√ß√£o e √† histologia dos tecidos investigados. Por fim, os resultados do estudo t√©cnica de imagem por espalhamento Compton permitiu avaliar a influ√™ncia de diferentes fatores relacionados ao feixe de radia√ß√£o, √† geometria e √† amostra, que determinam a qualidade das imagens obtidas.In this work we have been measured elastic and inelastic scattering from normal and neoplastic (benign and malignant) breast tissues using a photon energy of 17.44 keV (K? radiation ¬¨- Mo) and a scattering angle of 90¬ļ in order to determine the electron densities (?e), effective atomic number (Zef) and full width at half maximum (FWHM) of inelastic peak of these tissues. Compton scattering imaging techniques was also studied using computational simulation. The experimental methods were checked by analyzing of standard reference materials. The values of electron densities and effective atomic numbers obtained were compared with theoretical and experimental data previously published, showing good agreement between them (differences smaller than 5%). The values of FWHM indicate the possibility of using the FWHM for obtain information about the composition of tissues showing correlation with the values of Zef. The results also show that there are differences of ?e, Zef and FWHM between groups of tissues which are associated with the composition and histology of the investigated tissues. Finally, the results of the study of the Compton scattering imaging technique allowed assessing the influence of various factors, related to the radiation beam, geometry sample, which determine the image quality

    Neotropical freshwater fisheries : A dataset of occurrence and abundance of freshwater fishes in the Neotropics

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    The Neotropical region hosts 4225 freshwater fish species, ranking first among the world's most diverse regions for freshwater fishes. Our NEOTROPICAL FRESHWATER FISHES data set is the first to produce a large-scale Neotropical freshwater fish inventory, covering the entire Neotropical region from Mexico and the Caribbean in the north to the southern limits in Argentina, Paraguay, Chile, and Uruguay. We compiled 185,787 distribution records, with unique georeferenced coordinates, for the 4225 species, represented by occurrence and abundance data. The number of species for the most numerous orders are as follows: Characiformes (1289), Siluriformes (1384), Cichliformes (354), Cyprinodontiformes (245), and Gymnotiformes (135). The most recorded species was the characid Astyanax fasciatus (4696 records). We registered 116,802 distribution records for native species, compared to 1802 distribution records for nonnative species. The main aim of the NEOTROPICAL FRESHWATER FISHES data set was to make these occurrence and abundance data accessible for international researchers to develop ecological and macroecological studies, from local to regional scales, with focal fish species, families, or orders. We anticipate that the NEOTROPICAL FRESHWATER FISHES data set will be valuable for studies on a wide range of ecological processes, such as trophic cascades, fishery pressure, the effects of habitat loss and fragmentation, and the impacts of species invasion and climate change. There are no copyright restrictions on the data, and please cite this data paper when using the data in publications

    Highly-parallelized simulation of a pixelated LArTPC on a GPU

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    The rapid development of general-purpose computing on graphics processing units (GPGPU) is allowing the implementation of highly-parallelized Monte Carlo simulation chains for particle physics experiments. This technique is particularly suitable for the simulation of a pixelated charge readout for time projection chambers, given the large number of channels that this technology employs. Here we present the first implementation of a full microphysical simulator of a liquid argon time projection chamber (LArTPC) equipped with light readout and pixelated charge readout, developed for the DUNE Near Detector. The software is implemented with an end-to-end set of GPU-optimized algorithms. The algorithms have been written in Python and translated into CUDA kernels using Numba, a just-in-time compiler for a subset of Python and NumPy instructions. The GPU implementation achieves a speed up of four orders of magnitude compared with the equivalent CPU version. The simulation of the current induced on 10310^3 pixels takes around 1 ms on the GPU, compared with approximately 10 s on the CPU. The results of the simulation are compared against data from a pixel-readout LArTPC prototype