92 research outputs found
Brain tissue segmentation using q-entropy in multiple sclerosis magnetic resonance images
The loss of brain volume has been used as a marker of tissue destruction and can be used as an index of the progression of neurodegenerative diseases, such as multiple sclerosis. In the present study, we tested a new method for tissue segmentation based on pixel intensity threshold using generalized Tsallis entropy to determine a statistical segmentation parameter for each single class of brain tissue. We compared the performance of this method using a range of different q parameters and found a different optimal q parameter for white matter, gray matter, and cerebrospinal fluid. Our results support the conclusion that the differences in structural correlations and scale invariant similarities present in each tissue class can be accessed by generalized Tsallis entropy, obtaining the intensity limits for these tissue class separations. In order to test this method, we used it for analysis of brain magnetic resonance images of 43 patients and 10 healthy controls matched for gender and age. The values found for the entropic q index were 0.2 for cerebrospinal fluid, 0.1 for white matter and 1.5 for gray matter. With this algorithm, we could detect an annual loss of 0.98% for the patients, in agreement with literature data. Thus, we can conclude that the entropy of Tsallis adds advantages to the process of automatic target segmentation of tissue classes, which had not been demonstrated previously.Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)FAPESPCNP
Singular open book structures from real mappings
We prove extensions of Milnor's theorem for germs with nonisolated
singularity and use them to find new classes of genuine real analytic mappings
with positive dimensional singular locus \Sing \psi \subset
\psi^{-1}(0), for which the Milnor fibration exists and yields an open book
structure with singular binding.Comment: more remark
Monilófitas da Estação Ecológica do Panga, Uberlândia, Estado de Minas Gerais, Brasil: Dennstaedtiaceae, Dryopteridaceae, Gleicheniaceae, Hymenophyllaceae e Lindsaeaceae
Variabilidade dos índices de colheita de nutrientes em genótipos de feijoeiro e sua relação com a produção de grãos
Biostimulation of inoculation with Glomus proliferum and application of humic acid in the in vitro growth of Lunularia cruciata
Fine-root production in two secondary forest sites with distinct ages in Eastern Amazon
Avaliação dos efeitos do aspartame sobre a ingestão alimentar, os parâmetros físicos, bioquímicos e histopatológicos em ratos Wistar
Avaliação dos coeficientes de digestibilidade dos aminoácidos do grão de trigo e seus subprodutos para frangos de corte utilizando diferentes metodologias
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