The whole mesh Deformation Model for 2D and 3D image segmentation

In this paper we present a novel approach for image segmentation using Active Nets and Active Volumes. Those solutions are based on the Deformable Models, with slight difference in the method for describing the shapes of interests - instead of using a contour or a surface they represented the segmented objects with a mesh structure, which allows to describe not only the surface of the objects but also to model their interiors. This is obtained by dividing the nodes of the mesh in two categories, namely internal and external ones, which will be responsible for two different tasks. In our new approach we propose to negate this separation and use only one type of nodes. Using that assumption we manage to significantly shorten the time of segmentation while maintaining its quality

Scotin, a novel p53-inducible proapoptotic protein located in the ER and the nuclear membrane

p53 is a transcription factor that induces growth arrest or apoptosis in response to cellular stress. To identify new p53-inducible proapoptotic genes, we compared, by differential display, the expression of genes in spleen or thymus of normal and p53 nullizygote mice after γ-irradiation of whole animals. We report the identification and characterization of human and mouse Scotin homologues, a novel gene directly transactivated by p53. The Scotin protein is localized to the ER and the nuclear membrane. Scotin can induce apoptosis in a caspase-dependent manner. Inhibition of endogenous Scotin expression increases resistance to p53-dependent apoptosis induced by DNA damage, suggesting that Scotin plays a role in p53-dependent apoptosis. The discovery of Scotin brings to light a role of the ER in p53-dependent apoptosis

Stopping rules effect on a derivative-free filter multistart algorithm for multilocal programming

Fundação para a Ciência e a Tecnologia (FCT

Numerical experiments with nonconvex MINLP problems

We present a methodology to solve nonconvex Mixed-Integer Nonlinear Programming problems, that combines the Branch-and-Bound and simulated annealing type methods, which was implemented in MATLAB. A set of benchmark functions with simple bounds and different dimensions was used to analyze its practical behaviour. We exhibit computational results showing the good performance of the method.Fundação para a Ciência e a Tecnologia (FCT

A derivative-free filter driven multistart technique for global optimization

A stochastic global optimization method based on a multistart strategy and a derivative-free filter local search for general constrained optimization is presented and analyzed. In the local search procedure, approximate descent directions for the constraint violation or the objective function are used to progress towards the optimal solution. The algorithm is able to locate all the local minima, and consequently, the global minimum of a multi-modal objective function. The performance of the multistart method is analyzed with a set of benchmark problems and a comparison is made with other methods.This work was financed by FEDER funds through COMPETE-Programa Operacional Fatores de Competitividade and by portuguese funds through FCT-Fundação para a Ciência e a Tecnologia within projects PEst-C/MAT/UI0013/2011 and FCOMP- 01-0124-FEDER-022674

Interrupted searches in the BBMCSFilter context for MINLP problems

The BBMCSFilter method was developed to solve mixed integer nonlinear programming problems. This kind of problems have integer and continuous variables and they appear very frequently in process engineering problems. The objective of this work is to analyze the performance of the method when the coordinate searches are interrupted in the context of the multistart strategy. From the numerical experiments, we observed a reduction on the number of function evaluations and on the CPU time

Previsão do comportamento termo-reológico de fluidos viscoelásticos durante o escoamento em canais de geometria complexa

Pretende-se com o presente estudo aprofundar o conhecimento e apurar a sensibilidade necessária para lidar mais eficientemente com problemas reais, nomeadamente nas áreas de Extrusão e da Injecção. Para tal, simula-se numericamente o escoamento de fluidos incompressíveis, em estado estacionário no interior de um canal onde existem obstáculos cilíndricos à passagem do fluido. A análise é efectuada em três sistemas com configurações distintas, reduzidos, por considerações geométricas, a problemas bidimensionais e usando três fluidos distintos. Juntamente com as equações de Navier-Stokes utilizam-se duas leis materiais distintas para descrever o comportamento material do fluido: a lei de potência e o modelo de Maxwell (UCM). Para executar as simulações recorre-se ao programa de dinâmica de fluidos Polyflow - ferramenta computacional que discretiza as equações de Navier-Stokes pelo método de elementos finitos. Simulam-se situações de Extrusão em cada um dos três sistemas e de Injecção no sistema com estrangulamentos mais acentuados. Na situação de Extrusão, simulada para os dois fluidos viscosos o efeito da dissipação viscosa na temperatura do fluido é significativo. Para o fluido viscoelástico concluiu-se que os resultados obtidos são análogos ao do fluido Newtoniano. Na situação de Injecção, simulada com o fluido reofluidificante, não foram obtidos resultados com significado físico. No decurso das simulações ocorreram problemas de convergência relacionados com o parâmetro n da lei de potência, energia de activação e condutividade térmica do fluido. O problema é ultrapassado, no primeiro caso recorrendo ao método de Picard, e através de um processo evolutivo nos restantes casos