Theory of periodic swarming of bacteria: application to Proteus mirabilis

The periodic swarming of bacteria is one of the simplest examples for pattern formation produced by the self-organized collective behavior of a large number of organisms. In the spectacular colonies of Proteus mirabilis (the most common species exhibiting this type of growth) a series of concentric rings are developed as the bacteria multiply and swarm following a scenario periodically repeating itself. We have developed a theoretical description for this process in order to get a deeper insight into some of the typical processes governing the phenomena in systems of many interacting living units. All of our theoretical results are in excellent quantitative agreement with the complete set of available observations.Comment: 11 pages, 8 figure

Lubricating Bacteria Model for Branching growth of Bacterial Colonies

Various bacterial strains (e.g. strains belonging to the genera Bacillus, Paenibacillus, Serratia and Salmonella) exhibit colonial branching patterns during growth on poor semi-solid substrates. These patterns reflect the bacterial cooperative self-organization. Central part of the cooperation is the collective formation of lubricant on top of the agar which enables the bacteria to swim. Hence it provides the colony means to advance towards the food. One method of modeling the colonial development is via coupled reaction-diffusion equations which describe the time evolution of the bacterial density and the concentrations of the relevant chemical fields. This idea has been pursued by a number of groups. Here we present an additional model which specifically includes an evolution equation for the lubricant excreted by the bacteria. We show that when the diffusion of the fluid is governed by nonlinear diffusion coefficient branching patterns evolves. We study the effect of the rates of emission and decomposition of the lubricant fluid on the observed patterns. The results are compared with experimental observations. We also include fields of chemotactic agents and food chemotaxis and conclude that these features are needed in order to explain the observations.Comment: 1 latex file, 16 jpeg files, submitted to Phys. Rev.

Erros mais comuns e fatores de risco na administração de medicamentos em unidades básicas de saúde Errores mas comunes y factores de riesgo en la administración de medicamentos en las unidades básicas de salud Common errors and risk factors in medicine administration at basic health units

Este estudo identificou e analisou as opiniões de enfermeiros e profissionais de enfermagem sobre os fatores de risco mais comuns à ocorrência dos erros na administração de medicamentos, as conseqüências, intervenções tomadas e medidas que minimizariam essa ocorrência. Para tanto, aplicou-se um instrumento para coleta de dados contendo questões sobre as opiniões de profissionais de enfermagem, atuantes em Unidades Básicas de Saúde de uma cidade do interior paulista. Os resultados indicaram que os fatores de risco associados ao próprio profissional foram a falta de atenção e dificuldade de entender prescrições médicas. As intervenções tomadas estão relacionadas à punição e educação e as propostas para minimizar as ocorrências dos erros foram a orientação e reciclagem dos profissionais envolvidos.<br>Este estudio, de carácter cuantitativo, identificó y analizó los factores de riesgo mas comunes para la aparición de errores durante la administración de medicamentos, las consecuencias y medidas que disminuían la ocurrencia de los mismos, según las opiniones de los profesionales de enfermería de las unidades básicas de salud de una cuidad del interior de São Paulo. Los factores de riesgo asociados al propio profesional fueron la falta de atención y dificultad para entender las prescripciones médicas. Las intervenciones tomadas frente al error fueron el castigo, y la educación. Dentro de las propuestas para disminuir las ocurrencias de errores para este grupo de personas fueron la orientación, y la educación de los profesionales involucrados.<br>The present study identified and analyzed the opinions of nurses and nursing professionals about the more common risk factors regarding errors in medicine administration as well as the consequences, interventions and measures to minimize this problem. Therefore, the authors applied an instrument of data collection with questions on the opinions of the nursing professionals who work at the Basic Health Units from a city of the state of São Paulo. Results showed that the risk factors associated to the professional were lack of attention and difficulty to understand medical prescriptions. The interventions were related to punishment and education and the proposals to minimize the occurrences were orientation and up-date of the involved professionals