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Search Results: 1 - 10 of 71815 matches for " Maria Bruna "
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Diffusion in spatially varying porous media
Maria Bruna,S. Jonathan Chapman
Physics , 2015,
Abstract: The problem of diffusion in a porous medium with a spatially varying porosity is considered. The particular microstructure analyzed comprises a collection of impenetrable spheres, though the methods developed are general. Two different approaches for calculating the effective diffusion coefficient as a function of the microstructure are presented. The first is a deterministic approach based on the method of multiple scales; the second is a stochastic approach for small volume fraction of spheres based on matched asymptotic expansions. We compare the two approaches, and we show good agreement between them in a number of example configurations.
Diffusion of finite-size particles in confined geometries
Maria Bruna,S. Jonathan Chapman
Physics , 2012,
Abstract: The diffusion of finite-size hard-core interacting particles in two- or three-dimensional confined domains is considered in the limit that the confinement dimensions become comparable to the particle's dimensions. The result is a nonlinear diffusion equation for the one-particle probability density function, with an overall collective diffusion which depends on both the excluded-volume and the narrow confinement. By including both these effects the equation is able to interpolate between severe confinement (for example, single-file diffusion) and unconfined diffusion. Numerical solutions of both the effective nonlinear diffusion equation and the stochastic particle system are presented and compared. As an application, the case of diffusion under a ratchet potential is considered, and the change in transport properties due to excluded-volume and confinement effects is examined.
Excluded-volume effects in the diffusion of hard spheres
Maria Bruna,S. Jonathan Chapman
Mathematics , 2010, DOI: 10.1103/PhysRevE.85.011103
Abstract: Excluded-volume effects can play an important role in determining transport properties in diffusion of particles. Here, the diffusion of finite-sized hard-core interacting particles in two or three dimensions is considered systematically using the method of matched asymptotic expansions. The result is a nonlinear diffusion equation for the one-particle distribution function, with excluded-volume effects enhancing the overall collective diffusion rate. An expression for the effective (collective) diffusion coefficient is obtained. Stochastic simulations of the full particle system are shown to compare well with the solution of this equation for two examples.
Diffusion of multiple species with excluded-volume effects
Maria Bruna,S. Jonathan Chapman
Mathematics , 2012, DOI: 10.1063/1.4767058
Abstract: Stochastic models of diffusion with excluded-volume effects are used to model many biological and physical systems at a discrete level. The average properties of the population may be described by a continuum model based on partial differential equations. In this paper we consider multiple interacting subpopulations/species and study how the inter-species competition emerges at the population level. Each individual is described as a finite-size hard core interacting particle undergoing Brownian motion. The link between the discrete stochastic equations of motion and the continuum model is considered systematically using the method of matched asymptotic expansions. The system for two species leads to a nonlinear cross-diffusion system for each subpopulation, which captures the enhancement of the effective diffusion rate due to excluded-volume interactions between particles of the same species, and the diminishment due to particles of the other species. This model can explain two alternative notions of the diffusion coefficient that are often confounded, namely collective diffusion and self-diffusion. Simulations of the discrete system show good agreement with the analytic results.
Helicobacter pylori and upper gastrointestinal diseases: A review  [PDF]
Bruna Maria Roesler, Elizabeth Maria Afonso Rabelo-Gon?alves, José Murilo Robilotta Zeitune
Health (Health) , 2014, DOI: 10.4236/health.2014.64039

Since its first isolation by Marshall and Warren, Helicobacter pylori (H. pylori) has been recognized to have a causal role in the upper gastrointestinal diseases development, especially in chronic gastritis, peptic ulcer disease, mucosa-associated lymphoid tissue (MALT lymphoma) and gastric adenocarcinoma. H. pylori is a spiral-shaped gram-negative flagellate bacterium that has a high genetic diversity, which is an important factor in its adaptation to the host stomach and also for the clinical outcome of the infection, an aspect that remains unclear. However, it is thought to involve a interplay among the virulence of the infecting strain, host genetics and environmental factors. This review chapter brings the principal characteristics of the diseases associated with H. pylori infection and summarizes some important characteristics concerning the virulence of bacterium strain, host genetics and external environment.

Optimization of the Cultivation of Donor Mesenchymal Stromal Cells for Clinical Use in Cellular Therapy  [PDF]
Vanessa Valim, Bruna Amorin, Annelise Pezzi, Maria Aparecida Lima da Silva, Ana Paula Alegretti, Lucia Silla
CellBio (CellBio) , 2014, DOI: 10.4236/cellbio.2014.31003
Abstract: Mesenchymal stromal cells(MSC)have shown their benefits in graft-versus-host disease(GVHD), with five unsettled matters: 1) MSCs expansion in medium with Fetal Bovine Serum(FBS)and its risk of xenoreaction; 2) The number of cells indicated for therapy that is relatively high, with the need to optimize the expansion, number and time wise; 3) The utilization of third party donors; 4) Culture passage number(P);and 5) Source of the cells. This study was designed to determine the superiority of the Platelet Lysates(PL)over FBS on the expansion of MSC, the optimal cell plating density and days between each pass, and to investigate if donor total nucleated cells(TNC)obtained from the washouts of discharged bags and filters of hematopoietic stem cell transplantation(HSCT)can be expanded to be used at clinical grade. TNC were removed, plated and after the first passage were cultivated in different concentrations with FBS or PL, and the number of days to reach 80% of confluence was observed. Next, cultures with the same plating density were fed either with PL or with FBS and after seven days counted to analyze how much they had grown in that period. The proliferation of mesenchymal stromal cells in the presence of PL and SFB was averaged 11.88 and 2.5 times, respectively, in a period of 7 days. The highest concentration of plating cells using PL took less time to reach confluence as compared with the three lower ones. This study suggests that the PL is the best choice as a supplement to expand MSC and to allow the proliferation of enough number of MSC at P2 for clinical use.
Contribui es de Sabina Spielrein à psicanálise
Bruna Holst,Maria Lúcia Tiellet Nunes
Barbarói , 2012,
Abstract: Através da descoberta e revela o de documentos em 1977, a psicanalista Sabina Spielrein passou de longo período de esquecimento ao reconhecimento como um dos pilares do surgimento e propaga o da Psicanálise na Europa. Entretanto, sua história de vida, repleta de drama e supera o, ainda se sobrep e ao legado teórico que Spielrein proporcionou para a comunidade psicanalítica. Sua principal heran a da teoria e técnica construídas por Freud deu-se através de suas preposi es acerca do que, posteriormente, veio a ser conceituado como puls o de morte; Spielrein também é responsável por importantes teoriza es sobre o desenvolvimento da linguagem nas crian as. O objetivo deste ensaio bibliográfico é resgatar a história de vida desta psicanalista e discutir a teoria por ela formulada sobre linguística, teoria essa que somente foi descoberta anos depois de sua morte. Abstract Through the discovery and disclosure of documents in 1977, Sabina Spielrein arises from a long period of oblivion to now be recognized as one of the pillars of the emergence and spread of psychoanalysis in Europe. Her full of drama and overcoming life story overlaps the theoretical legacy that Spielrein provided to psychoanalytic community. Her main legacy to Freud s theory and technique was her prepositions about what later came to be conceptualized as the death drive Spielrein was also responsible for major theories about the understanding of children s language development. The aim of this paper is to review her life story and provide a discussion about her linguistics theory, which has only been discovered years after her death.
Bruna Letícia Thomas,Eliane Maria Foleto
Revista Eletr?nica do Curso de Direito da UFSM , 2013, DOI: 10.5902/198136948401
Abstract: O presente artigo aborda o desenvolvimento das áreas Protegidas no país, a partir da evolu o das legisla es ambientais que as estabelecem. Desta forma, esta pesquisa desenvolveu-se a partir de leituras, pesquisas científicas e debates no laboratório Hidrogeo acerca da temática áreas Protegidas e os meios legais vinculadas a ela, como o Código Florestal de 1934 e 1965, a Política Nacional do Meio Ambiente e o Sistema Nacional de Unidades de Conserva o da Natureza, entre outras. Assim, percebe-se que a evolu o da legisla o ocorreu concomitantemente com mudan as relacionadas aos estudos ambientais, melhorando estes espa os de prote o e sua eficácia em garantir a sustentabilidade e equilíbrio ambiental
Fotoetnografia: a importancia da fotografia para o resgate etnográfico Paulo César Boni, Bruna Maria Moreschi
Paulo César Boni,Bruna Maria Moreschi
Doc On-Line : Revista Digital de Cinema Documentário , 2007,
Abstract: This paper describes the use of photography in an ethnographical approach. It traces historically the growing importance of image in anthropological studies. It lists photographers and anthropologists, including Brazilians who employ photography to retrieve people and social groups. Based on available bibliography and on newly-published texts cited in the body of this work, it concludes that, throughout time, photography is increasingly being incorporated as a source for ethnographical research.
Maria Augusta Justi Pisani,Gilda Collet Bruna
Engevista , 2011,
Abstract: The floods in urbanized areas damage systemically the Brazilian municipalities during the highraining periods. The economic lost that the nation face with this phenomenon are not yet measured, althoughthrough the impacts’ extension it is possible to observe that they are affecting the South and Southeastregions during this decade. Disasters within the urban tissue are complex, as they turn the various types ofrisks in a mess, mixing the natural risks with the social ones and also with the technological and biologicalrisks. If society occupies inadequate areas like the floodplains of the rivers and change the hydrologicalregime of the river basins, they pay a higher price, both with the public works to control these floods, andwith the losses generated with floods and their aftermath. So, controlling a flood means intervene in severalprocesses and involved elements, trying to minimize their effects. The recognition and monitoring of areassubject to risk are indispensable tools to for avoiding or reducing the undesired effects and the measures thatassist the management of flooded areas are: maintenance, structural and non structural measures.This article objective is to study the potentialities of the non structural measures to combat the accidentsrelated to floods, through a local research. These measures can be adopted by the architects and urban planners and engineering professionals and collaborate in a systemic and efficient form to decrease these natural disasters damages and frequency.The first methodological procedure used for this research was the survey of actions and public worksimplemented in European, Asian and American cities during the last decade and analyze the probabilityof adapting these works to the Brazilian reality. These research findings are important subsidies for thepublic policies and urban projects development so that they minimize the urban floods, thus helping thesustainable development.
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