On the simple random-walk models of ion-channel gate dynamics reflecting long-term memory

Several approaches to ion-channel gating modelling have been proposed. Although many models describe the dwell-time distributions correctly, they are incapable of predicting and explaining the long-term correlations between the lengths of adjacent openings and closings of a channel. In this paper we propose two simple random-walk models of the gating dynamics of voltage and Ca2+-activated potassium channels which qualitatively reproduce the dwell-time distributions, and describe the experimentally observed long-term memory quite well. Biological interpretation of both models is presented. In particular, the origin of the correlations is associated with fluctuations of channel mass density. The long-term memory effect, as measured by Hurst R/S analysis of experimental single-channel patch-clamp recordings, is close to the behaviour predicted by our models. The flexibility of the models enables their use as templates for other types of ion channel

Um método construtivista para a avaliação em saúde A Constructivist method for health evaluation

Este texto realiza uma investigação sobre métodos potencialmente mais adequados para a avaliação de serviços e programas a partir das questões apresentadas pela política de desinstitucionalização em saúde e pelas limitações da avaliação ortodoxa. Percorremos diferentes concepções de avaliação de programas e serviços e identificamos na proposta de avaliadores de quarta geração (Guba & Lincoln, 1989) potencial capaz de superar alguns destes impasses e questões. Finalmente propomos a aproximação do Método Paidéia (Campos, 2000-a) à abordagem de Avaliação de Quarta Geração, procurando estabelecer coerência entre avaliação e sistema de gestão participativa.<br>This paper realizes an investigation about the most adequate methods to evaluate services and programs based in questions placed by the health politics of deinstitutionalization and by the limitations of the orthodox evaluation. We explore different concepts of programs and services evaluation and identify a potential to excel some of these issues in the proposal of the fourth generation method (Guba & Lincoln, 1989). Finally we propose an approximation of the Paidéia method (Campos, 2000-a) to the fourth generation method, trying to connect evaluation to participative management system