Coleção de Artigos Acadêmicos
URI permanente para esta coleçãohttps://repositorio.insper.edu.br/handle/11224/3227
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26 resultados
Resultados da Pesquisa
Artigo Científico Estimation of the tissue composition of the tumour mass in neuroblastoma using segmented CT images(2004) FABIO JOSE AYRES; M. K. Zuffo,; Rangayyan, R. M.; Boag, G. S.; O. Filho, V.; Valente , M.Neuroblastoma is the most common extra-cranial, solid, malignant tumour in children. Advances in radiology have made possible the detection and staging of the disease. Nevertheless, there is no method available at present that can go beyond detection and qualitative analysis, towards quantitative assessment of the tissues composition of the primary tumour mass in neuroblastoma. Such quantitative analysis could provide important information and serve as a decision-support tool to the radiologist and the oncologist, result in better treatment and follow-up and even lead to the avoidance of delayed surgery. The problem investigated was the improvement of the analysis of the primary tumour mass, in patients with neuroblastoma, using X-ray computed tomography (CT) images. A methodology was proposed for the estimation of the tissue content of the mass: it comprised a Gaussian mixture model for estimation, from segmented CT images, of the tissue composition of the primary tumour. To demonstrate the potential of the method, the results are presented of its application to ten CT examinations of four patients. The method provides quantitative information, and it was observed that the tumour in one of the patients reduced from 523 cm3 to 81 cm3 in volume, with an increase in calcification from about 20% to about 88% of the tumour volume, in response to chemotherapy over a period of five months. Results indicate that the proposed technique may be of considerable value in assessing the response to therapy of patients with neuroblastoma.Artigo Científico Gabor filters and phase portraits for the detection of architectural distortion in mammograms(2006) Rangayyan, Rangaraj M.; FABIO JOSE AYRESSegmentation of the tumor in neuroblastoma is complicated by the fact that the mass is almost Always heterogeneous in nature; furthermore, viable Architectural distortion is a subtle abnormality in mammograms, and a source of overlooking errors by radiologists. Computer-aided diagnosis (CAD) techniques can improve the performance of radiologists in detecting masses and calcifications; however, most CAD systems have not been designed to detect architectural distortion. We present a new method to detect and localise architectural distortion by analysing the oriented texture in mammograms. A bank of Gabor filters is used to obtain the orientation field of the given mammogram. The curvilinear structures (CLS) of interest (spicules and fibrous tissue) are separated from confounding structures (pectoral muscle edge, parenchymal tissue edges, breast boundary, and noise). The selected core CLS pixels and the orientation field are filtered and downsampled, to reduce noise and also to reduce the computational effort required by the subsequent methods. The downsampled orientation field is analysed to produce three phase portrait maps: node, saddle, and spiral. The node map is further analysed in order to detect the sites of architectural distortion. The method was tested with 19 mammograms containing architectural distortion. In a preliminary experiment, a sensitivity of 84% was obtained at 7.8 false positives per image.Artigo Científico Coordinating collaborative joint efforts with suppliers: the effects of trust, transaction specific investment and information network in the Dutch flower industry(2006) DANNY PIMENTEL CLARO; PRISCILA BORIN DE OLIVEIRA CLARO; Hagelaar, GeoffreyArtigo Científico Building collaborative relationships with distributors in the dutch potted flower and plant industry(2005) DANNY PIMENTEL CLARO; Omta, OnnoArtigo Científico Coordinating B2B cross-border supply chains: the case of the organic coffee industry(2004) DANNY PIMENTEL CLARO; PRISCILA BORIN DE OLIVEIRA CLAROArtigo Científico How to manage a long-term buyer-supplier relationship successfully? The impact of network information on long-term buyer-supplier relationships in the Dutch potted plant and flower industry(2004) DANNY PIMENTEL CLARO; PRISCILA BORIN DE OLIVEIRA CLARO; Omta, Onno S. W. F.Artigo Científico Finding a maximum skewness portfolio - a general solution to three-moments portfolio choice(2004) GUSTAVO MONTEIRO DE ATHAYDE; Flôres Junior, Renato GalvãoArtigo Científico Full Dollarization: The Case of Panama(2001) GINO ABRAHAM OLIVARES LEANDRO; Goldfajn, IlanArtigo Científico Convergence clubs among brazilian municipalities(2004) Andrade, Eduardo; Laurini, Márcio; Madalozzo, Regina Carla; Pereira, Pedro L. VallsArtigo Científico Rising human capital but constant inequality: the education composition effect in Brazil(2006) NAERCIO AQUINO MENEZES FILHO; Fernandes, Reynaldo; Picchetti, PauloEste artigo examina o impacto da composição educacional da força de trabalho e dos retornos à educação sobre a dispersão dos salários dos homens no Brasil nos últimos 20 anos. Ele aplica uma regressão quantifica sobre um polinômio de idade, tendência e interações usando dados das PNADs entre 1977 e 1997. Os resultados indicam que o aumento da escolaridade da população brasileira não provocou uma queda da desigualdade porque as mudanças na composição educacional contribuíram para um aumento da desigualdade. As simulações indicam que o efeito de composição vai contribuir para uma queda substancial da desigualdade no futuro próximo.
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