2,969 research outputs found

    Aspirin-Exacerbated Asthma

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    <p/> <p>This review focuses on aspirin-exacerbated asthma (AEA). The review includes historical perspective of aspirin, prevalence, pathogenesis, clinical features and treatment of AEA. The pathogenesis of AEA involves the cyclooxygenase and lipooxygenase pathway. Aspirin affects both of these pathways by inhibiting the enzyme cycooxygenase-1 (COX-1). Inhibition of COX-1 leads to a decrease in prostaglandin E2 (PGE2). The decrease in PGE2 results in an increase in cysteinyl leukotrienes by the lipooxygenase pathway involving the enzyme 5-lipooxygenase (5-LO). Leukotriene C4 (LTC<sub>4</sub>) synthase is the enzyme responsible for the production of leukotriene C4, the chief cysteinyl leukotriene responsible for AEA. There have been familial occurences of AEA. An allele of the LTC<sub>4 </sub>synthase gene in AEA is known as allele C. Allele C has a higher frequency in AEA. Clinical presentation includes a history of asthma after ingestion of aspirin, nasal congestion, watery rhinorrhea and nasal polyposis. Treatment includes leukotriene receptor antagonists, leukotriene inhibitors, aspirin desinsitaztion and surgery. AEA is the most well-defined phenotype of asthma. Although AEA affects adults and children with physician-diagnosed asthma, in some cases there is no history of asthma and AEA often goes unrecognized and underdiagnosed.</p

    Visual Mining of Epidemic Networks

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    We show how an interactive graph visualization method based on maximal modularity clustering can be used to explore a large epidemic network. The visual representation is used to display statistical tests results that expose the relations between the propagation of HIV in a sexual contact network and the sexual orientation of the patients.Comment: 8 page

    Yang-Mills theory for bundle gerbes

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    Given a bundle gerbe with connection on an oriented Riemannian manifold of dimension at least equal to 3, we formulate and study the associated Yang-Mills equations. When the Riemannian manifold is compact and oriented, we prove the existence of instanton solutions to the equations and also determine the moduli space of instantons, thus giving a complete analysis in this case. We also discuss duality in this context.Comment: Latex2e, 7 pages, some typos corrected, to appear in J. Phys. A: Math. and Ge

    Bifurcation, chaos, and voltage collapse in power systems

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    A model of a power system with load dynamics is studied by investigating qualitative changes in its behavior as the reactive power demand at a load bus is increased. In addition to the saddle node bifurcation often associated with voltage collapse, the system exhibits sub- and supercritical Hopf bifurcations, cyclic fold bifurcation, and period doubling bifurcation. Cascades of period doubling bifurcations terminate in chaotic invariant sets. The presence of these new bifurcations motivates a reexamination of the saddle-node bifurcation as the boundary of the feasible set of power injections.published_or_final_versio
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