Species survival and scaling laws in hostile and disordered environments

In this work we study the likelihood of survival of single-species in the context of hostile and disordered environments. Population dynamics in this environment, as modeled by the Fisher equation, is characterized by negative average growth rate, except in some random spatially distributed patches that may support life. In particular, we are interested in the phase diagram of the survival probability and in the critical size problem, i.e., the minimum patch size required for surviving in the long time dynamics. We propose a measure for the critical patch size as being proportional to the participation ratio (PR) of the eigenvector corresponding to the largest eigenvalue of the linearized Fisher dynamics. We obtain the (extinction-survival) phase diagram and the probability distribution function (PDF) of the critical patch sizes for two topologies, namely, the one-dimensional system and the fractal Peano basin. We show that both topologies share the same qualitative features, but the fractal topology requires higher spatial fluctuations to guarantee species survival. We perform a finite-size scaling and we obtain the associated scaling exponents. In addition, we show that the PDF of the critical patch sizes has an universal shape for the 1D case in terms of the model parameters (diffusion, growth rate, etc.). In contrast, the diffusion coefficient has a drastic effect on the PDF of the critical patch sizes of the fractal Peano basin, and it does not obey the same scaling law of the 1D case.Comment: 20 pages, 5 Figure

Two stochastic optimization algorithms applied to nuclear reactor core design

Two stochastic optimization algorithms conceptually similar to Simulated Annealing are presented and applied to a core design optimization problem previously solved with Genetic Algorithms. The two algorithms are the novel Particle Collision Algorithm (PCA), which is introduced in detail, and Dueck’s Great Deluge Algorithm (GDA). The optimization problem consists in adjusting several reactor cell parameters, such as dimensions, enrichment and materials, in order to minimize the average peak factor in a three-enrichment-zone reactor, considering restrictions on the average thermal flux, criticality and sub-moderation. Results show that the PCA and the GDA perform very well compared to the canonical Genetic Algorithm and its variants, and also to Simulated Annealing, hence demonstrating their potential for other optimization applications

An optimization model for metabolic pathways

This article is available open access through the publisher’s website through the link below. Copyright @ The Author 2009.Motivation: Different mathematical methods have emerged in the post-genomic era to determine metabolic pathways. These methods can be divided into stoichiometric methods and path finding methods. In this paper we detail a novel optimization model, based upon integer linear programming, to determine metabolic pathways. Our model links reaction stoichiometry with path finding in a single approach. We test the ability of our model to determine 40 annotated Escherichia coli metabolic pathways. We show that our model is able to determine 36 of these 40 pathways in a computationally effective manner. Contact: [email protected] Supplementary information: Supplementary data are available at Bioinformatics online (http://bioinformatics.oxfordjournals.org/cgi/content/full/btp441/DC1)

La méthodologie Paideia dans la formation en santé

L’article rend compte d’une recherche-intervention menée dans un cours de formation continue proposé aux professionnels de soins primaires du système de santé brésilien. Le cours a adopté comme référentiel pédagogique le « soutien Paideia », une méthodologie qui associe théorie et pratique, partant des problèmes concrets pour développer la capacité de réflexion et d’action des sujets (Campos, 2000). Le but de la recherche a été d’analyser les effets de l’usage de ce cadre méthodologique sur la formation et la pratique des professionnels, en prenant en compte la subjectivité. À partir de l’analyse d’un cas clinique suivi pendant le cours et des focus groups, nous avons identifié le développement de nouvelles connaissances, postures et compétences, essentielles à l’approche de la subjectivité. Les professionnels ont développé leur capacité de réflexivité critique et une posture plus ouverte à l’écoute et au partage des décisions avec les patients. Ils ont développé des savoirs et des compétences pour le travail interprofessionnel et en équipe, aussi bien que pour la gestion du travail dans le contexte des soins primaires. Nous avons conclu également que l’articulation entre réflexion et intervention peut contribuer à produire des changements chez les sujets, dans leurs pratiques et dans les services de santé.The article reports an intervention study conducted during a continuing education course for primary health care professionals working in the Brazilian health system. The course adopted as a teaching reference the ‘Paideia support’, a methodology which combines theory and practice, using concrete problems to develop the subjects’ capacity for reflection and action (Campos, 2000). The aim of the study was to analyse the effects of this methodological framework on the training of the professionals involved and on their professional practice, with an emphasis on subjectivity. From the analysis of a clinical case followed during the course and “focus groups”, we identified the development of new knowledge, skills and stances, which are essential for the subjectivity approach. The professionals developed their critical-reflexivity, their listening skills and their ability to involve patients in the decision-making process. They gained knowledge and skills for use in group and inter-professional work, as well as for the management of work in the context of primary health care. We also concluded that this linkage between reflection and action can help to bring about changes in people, their practices, and also in health services

Evaluación del sonido del patrón de deglución en pacientes con trastorno temporomandibular

Objectives: The impairment of the temporomandibular joint and masticatory muscles has a negative impact on functions of the stomatognathic system, such as swallowing. Thus, an atypical swallowing pattern may contribute to the development of temporomandibular disorder (TMD). The aim of the present study was to evaluate acoustic aspects of swallowing and determine the occurrence of atypical swallowing dynamics. Methods: Sixty-two individuals [16 males (25.8%) and 46 females (74.2%); mean age 39.84 (± 9.40); 47 with TMD and 15 without TMD] were evaluated using an ultrasound detector during the swallowing of three consistencies: liquid, pasty and solid. The acoustic signals were recorded and subsequently analyzed using the DeglutiSom® software. Results: The majority of the sample (81%) with TMD presented atypical swallowing biodynamics, with a significantly greater frequency of food residuals for the three consistencies. The signal suggestive of aspiration was more frequent with the liquid consistency (37% of the group). Conclusion: There is a relation between TMD and an atypical swallowing pattern, which underscores the need for the multidisciplinary evaluation of individuals with this disorder.info:eu-repo/semantics/publishedVersio

Percepções dos agentes comunitários de saúde em um município do interior de São Paulo acerca da vigilância sanitária e atenção básica

O objetivo deste estudo foi compreender a relação entre a Vigilância Sanitária e a Atenção Primária, especificamente na Estratégia de Saúde da Família, em um município do interior de São Paulo. Buscou-se a percepção, dos Agentes Comunitários de Saúde (ACS), suas ações, as potencialidades e fragilidades relacionadas a essa interação. Trata-se de uma pesquisa de natureza qualitativa, desenvolvida a partir de entrevistas semiestruturadas com Agentes Comunitários de Saúde. Os dados foram tratados com base no conteúdo temático das entrevistas e organizados em categorias: o trabalho do ACS e a integralidade da atenção à saude; a concepção de Vigilância Sanitária; dificuldades e facilidades para o desenvolvimento de ações articuladas. Os resultados demonstraram que as percepções dos ACS, quanto às práticas e ações de Vigilância Sanitária no contexto das suas ações na Estratégia de Saúde da Família, remetem quase que exclusivamente para as questões regulatórias e de fiscalização, em detrimento das ações de promoção e proteção da saúde. Porém, identificou-se que algumas ações de Vigilância Sanitária são realizadas no âmbito da Atenção Primária, porém não são percebidas pelos agentes como tal. Portanto, é fundamental que essa discussão seja oportunizada no âmbito do Sistema Único de Saúde, buscando estratégias para uma maior integração entre a Vigilância Sanitária e a Atenção Básica