RESUMO A solução de sistemas de equações lineares, representados por Ax = b, é fundamental em diversas aplicações científicas e em engenharia. Ao se reduzir o profile da matriz A, pode-se reduzir a ocupação de espac¸o e o tempo de processamento da resolução de tais sistemas de equações lineares. Neste trabalho, propomos um algoritmo generalizado para encontrar vértices pseudoperiféricos para o algoritmo heurístico de Snay. Baseados em experimentos realizados em 36 instâncias contidas nas bases de matrizes Harwell-Boeing e SuiteSparse, verificou-se que o n´umero de vértices pseudoperiféricos selecionados pelo algoritmo de Snay pode ser adequado para instâncias pequenas, mas é insuficiente para obter resultados razo´aveis em instâncias que não são pequenas. Neste artigo, recomendamos a seleção de até 26% (0,3%) de vértices pseudoperiféricos em relação ao tamanho da instância, quando o algoritmo heurístico de Snay é aplicado em instâncias menores que 3.000 (maiores que 20.000) vértices.

ABSTRACT The solution of linear systems represented by Ax=b is fundamental in many numerical simulations in science and engineering. Reducing the profile of A can reduce the storage requirements and time processing costs of solving such linear systems. In this work, we propose a generalized algorithm for finding pseudo-peripheral vertices for Snay’s heuristic. In experiment performed on 36 instances contained in the Harwell-Boeing and SuiteSparse matrix collections, it has been found that the number of pseudo-peripheral vertices selected in Snay’s heuristic may be suitable for small instances, but it is insufficient to obtain reasonable results in instances that are not small. This paper recommends to select up to 26% (0.3%) of pseudo-peripheral vertices in relation to the instance size when applied to instances smaller than 3,000 (larger than 20,000) vertices.

Propolis has been the subject of several recent studies, with the aim of elucidating its biological and pharmacological properties. Propolis has a well-known antimicrobial activity as well as antioxidant, antitumoral, antiinflammatory, and regenerative properties, but literature about its effects on the immune response is scarce. The goal of this work was to evaluate the propolis effect on macrophage activation by oxygen (H2O2) and nitrogen (NO) metabolite determination. Propolis was produced by africanized honeybees and hydroalcoholic solutions were prepared at different concentrations. Peritoneal macrophages were obtained from male BALB/c mice and culture cells were stimulated in vitro with propolis or interferon-gamma (IFN-gamma). In the in vivo assay, the animals were sacrificed after propolis treatment and cells were stimulated with IFN-gamma. We also investigated the co-stimulant action of propolis associated with IFN-gamma on macrophages. The results show that propolis induces a discreet elevation in H2O2 release and a mild inhibition of NO generation, depending on concentration. Propolis had no co-stimulant activity, diminishing IFN-gamma action on H2O2 and NO production. Data suggest that propolis acts on host non-specific immunity by macrophage activation.