Emergence of Hierarchy on a Network of Complementary Agents

Complementarity is one of the main features underlying the interactions in biological and biochemical systems. Inspired by those systems we propose a model for the dynamical evolution of a system composed by agents that interact due to their complementary attributes rather than their similarities. Each agent is represented by a bit-string and has an activity associated to it; the coupling among complementary peers depends on their activity. The connectivity of the system changes in time respecting the constraint of complementarity. We observe the formation of a network of active agents whose stability depends on the rate at which activity diffuses in the system. The model exhibits a non-equilibrium phase transition between the ordered phase, where a stable network is generated, and a disordered phase characterized by the absence of correlation among the agents. The ordered phase exhibits multi-modal distributions of connectivity and activity, indicating a hierarchy of interaction among different populations characterized by different degrees of activity. This model may be used to study the hierarchy observed in social organizations as well as in business and other networks.Comment: 13 pages, 4 figures, submitte

Gastric Antral Vascular Ectasia (GAVE) and Hereditary Hemorrhagic Telangiectasia (HHT): Two Different Conditions, One Treatment

info:eu-repo/semantics/publishedVersio

Immunization and Aging: a Learning Process in the Immune Network

The immune system can be thought as a complex network of different interacting elements. A cellular automaton, defined in shape-space, was recently shown to exhibit self-regulation and complex behavior and is, therefore, a good candidate to model the immune system. Using this model to simulate a real immune system we find good agreement with recent experiments on mice. The model exhibits the experimentally observed refractory behavior of the immune system under multiple antigen presentations as well as loss of its plasticity caused by aging.Comment: 4 latex pages, 3 postscript figures attached. To be published in Physical Review Letters (Tentatively scheduled for 5th Oct. issue

Colite a CMV Mimetizando Tumor Rectal num Doente com VIH Não Diagnosticado

Introduction: Cytomegalovirus (CMV) is the most common opportunistic agent in HIV-infected patients. It can affect the entire gastrointestinal tract, but frequently involves the oesophagus and the colon. Case Report: We report the case of a 70-year-old female, ultimately diagnosed with HIV infection, whose inaugural clinical manifestation was CMV colitis with endoscopic findings resembling a rectal tumour in which initial histological evaluation was not able to provide a proper diagnosis. Discussion/Conclusion: Since clinical presentation is variable and histopathological yield without immunohistochemical analysis is poor, recognizing CMV infection in the absence of known risk factors may be difficult. It is crucial to consider this entity with suspicious lesions or when initial evaluation, either clinical or histopathological, is inconclusive, thus avoiding potentially debilitating and superfluous treatment or life-threatening complications.info:eu-repo/semantics/publishedVersio

Exatidão de classificações automáticas de uma imagem LANDSAT 5 TM para a região cafeeira de Machado, MG.

O presente trabalho avalia a acurácia de dois classificadores automáticos disponíveis no Sistema de Informação Geográfica SPRING para o mapeamento de uso e ocupação da terra da região cafeeira de Machado, MG. Foram utilizados os classificadores: Battacharya, ?por região?; e o Máxima Verossimilhança (Maxver), ?pixel a pixel? para a imagem Landsat 5 TM e como referência foi utilizada a imagem do satélite Spot 4 classificada visualmente e validada em campo. Ambos algoritmos demonstraram baixo rendimento para a região. Posteriormente às classificações, foram criadas matrizes de erro, comparando as classificações automáticas com a visual. O desempenho das classificações foi avaliado pelos índices de exatidão Global, Kappa e Tau. O baixo desempenho das classificações pode ser explicado pela região cafeeira de Machado possuir um relevo muito movimentado, proporcionando regiões sombreadas e lavouras cafeeiras contíguas a fragmentos de vegetação nativa, os quais apresentam resposta espectral semelhante

Análise de marmoreio de contra-filé através de imagens obtidas por Tomografia de Ressonância Magnética.

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Nano-Aptamer for Breast Cancer Imaging: Initial Considerations.

The application of aptamers especially in the use of drug delivery systems (DDSs) has the potential to develop in vivo nanoparticles for theranosis (therapy+diagnosis). With the advent of medical imaging and radiotherapeutics, this area of research developing the next era of radiopharmaceuticals is both attractive and promising. Overall, nano-radiopharmaceuticals have the potential to solve several problems regarding the in vivo stability of aptamers. This paper discusses a study in the development and proof-of-concept of nano-aptamers and supporting its use as a nano-radiopharmaceutical for the treatment of breast cancer and other potentially related disease states

Sexagem de Aves Silvestres sem Dimorfismo Sexual via Tomografia Por Ressonância Magnética Nuclear.

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