Sérgio Lifschitz

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We present algorithms for computing some distance functions between two (possibly intersecting) polygons, both in the convex and nonconvex cases. The interest for such distance functions comes from applications in robot vision, pattern recognition and contour fitting. We present a linear sequential algorithm and an optimal EREW·PRAM parallel algorithm for(More)
In the database area, elasticity of cloud computing has required data systems to increase and decrease their resources on demand. However, traditional benchmark tools for data systems are not sufficient to analyze some specificities of these systems in a cloud. New metrics for elasticity are needed to provide an indicator both from consumer and provider(More)
We propose an object-oriented framework for one of the most frequent and costly operations in parallel database systems: the parallel join. The framework independently captures a great variety of parameters, such as different load balancing procedures and different synchronization disciplines. The framework addresses DBMS flexibility, configuration and(More)
In this work, we used the PROV-DM model to manage data provenance in workflows of genome projects. This provenance model allows the storage of details of one workflow execution, e.g., raw and produced data and computational tools, their versions and parameters. Using this model, biologists can access details of one particular execution of a workflow,(More)
In this work we investigate the parallel evaluation of BLAST, the most popular tool for comparing biological sequences. Our goal is to study database distribution issues that, besides workload balancing, could improve the performance of a set of BLAST processes running in a workstation cluster. We consider different partitioning strategies within actual(More)
Postoperative wound breakdown is very common following the en bloc dissection of the vulva and inguinal/femoral lymph nodes for carcinoma of the vulva. To decrease the incidence of wound morbidity, techniques have been described for performing the inguinal/femoral lymphadenectomy through separate groin incisions. This approach leaves a bridge of tissue(More)
We study a dose-driven dynamic load balancing strategy to evaluate database recursive queries. This proposal aims at obtaining a good workload balance with full use of the available resources, with different kinds of skew considered. The strategy is intended for general recursive queries and preliminary computational results illustrate its ef-ciency when(More)
Mobile computing allows for the development of new and sophisticated database applications. Such applications require the reading of current and consistent data. In order to improve data availability, increase performance and maximize throughput, data replication is used. However, due to inherent limitations in mobile and other loosely-coupled environments,(More)