627 research outputs found

    Exact Solutions to the Sine-Gordon Equation

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    A systematic method is presented to provide various equivalent solution formulas for exact solutions to the sine-Gordon equation. Such solutions are analytic in the spatial variable xx and the temporal variable t,t, and they are exponentially asymptotic to integer multiples of 2π2\pi as x±.x\to\pm\infty. The solution formulas are expressed explicitly in terms of a real triplet of constant matrices. The method presented is generalizable to other integrable evolution equations where the inverse scattering transform is applied via the use of a Marchenko integral equation. By expressing the kernel of that Marchenko equation as a matrix exponential in terms of the matrix triplet and by exploiting the separability of that kernel, an exact solution formula to the Marchenko equation is derived, yielding various equivalent exact solution formulas for the sine-Gordon equation.Comment: 43 page

    A Purified Capsular Polysaccharide Markedly Inhibits Inflammatory Response during Endotoxic Shock

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    Capsular material of the opportunistic fungus Cryptococcus neoformans is mainly composed of a polysaccharide named glucuronoxylomannan (GXM). In this study, the effects of GXM were analyzed in an in vivo experimental system of LPS-induced shock. Endotoxic shock was induced in mice by a single intraperitoneal injection of LPS from Escherichia coli. GXM treatment reduced the mortality of mice at early stages. Mice treated with LPS alone showed markedly increased plasma levels of TNF-α, IL-1β, and IL-6, whereas mice treated with GXM too showed significantly lower plasma levels of these cytokines. This effect was related to a marked suppression of Akt and IkBα activation. Importantly, the inhibitory effect of GXM on pro-inflammatory cytokine secretion was reproduced by treatment with Wortmannin, an inhibitor of the Akt transcription pathway. Our results indicate that GXM has a beneficial effect on endotoxic shock, resulting in a significant increase in rate of survival by dampening the hyper-inflammatory response

    Topological Phenomena in the Real Periodic Sine-Gordon Theory

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    The set of real finite-gap Sine-Gordon solutions corresponding to a fixed spectral curve consists of several connected components. A simple explicit description of these components obtained by the authors recently is used to study the consequences of this property. In particular this description allows to calculate the topological charge of solutions (the averaging of the xx-derivative of the potential) and to show that the averaging of other standard conservation laws is the same for all components.Comment: LaTeX, 18 pages, 3 figure

    Merleau-Ponty and neuroaesthetics: Two approaches to performance and technology

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    This is an Author's Accepted Manuscript of an article published in Digital Creativity, 23(3-4), 225 - 238, 2012. Copyright @ 2012 Taylor & Francis, available online at: http://www.tandfonline.com/10.1080/14626268.2012.709941.Assisted by the rapid growth of digital technology, which has enhanced its ambitions, performance is an increasingly popular area of artistic practice. This article seeks to contextualise this within two methodologically divergent yet complimentary intellectual tendencies. The first is the work of the philosopher Merleau-Ponty, who recognised that our experience of the world has an inescapably ‘embodied’ quality, not reducible to mental accounts, which can be vicariously extended through specific instrumentation. The second is the developing field of neuroaesthetics; that is, neurological research directed towards the analysis, in brain-functional terms, of our experiences of objects and events which are culturally deemed to be of artistic significance. I will argue that both these contexts offer promising approaches to interpreting developments in contemporary performance, which has achieved critical recognition without much antecedent theoretical support

    Evaluation of a novel point-of-care cryptococcal antigen test on serum, plasma, and urine from patients with HIV-associated cryptococcal meningitis.

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    BACKGROUND: Many deaths from cryptococcal meningitis (CM) may be preventable through early diagnosis and treatment. An inexpensive point-of-care (POC) assay for use with urine or a drop of blood would facilitate early diagnosis of cryptococcal infection in resource-limited settings. We compared cryptococcal antigen (CRAG) concentrations in plasma, serum, and urine from patients with CM, using an antigen-capture assay for glucuronoxylomannan (GXM) and a novel POC dipstick test. METHODS: GXM concentrations were determined in paired serum, plasma, and urine from 62 patients with active or recent CM, using a quantitative sandwich enzyme-linked immunosorbent assay (ELISA). A dipstick lateral-flow assay developed using the same monoclonal antibodies for the sandwich ELISA was tested in parallel. Correlation coefficients were calculated using Spearman rank test. RESULTS: All patients had detectable GXM in serum, plasma, and urine using the quantitative ELISA. Comparison of paired serum and plasma showed identical results. There were strong correlations between GXM levels in serum/urine (r(s) = 0.86; P < .001) and plasma/urine (r(s) = 0.85; P < .001). Levels of GXM were 22-fold lower in urine than in serum/plasma. The dipstick test was positive in serum, plasma, and urine in 61 of 62 patients. Dipstick titers correlated strongly with ELISA. Correlations between the methods were 0.93 (P < .001) for serum, 0.94 (P < .001) for plasma, and 0.94 (P < .001) for urine. CONCLUSIONS: This novel dipstick test has the potential to markedly improve early diagnosis of CM in many settings, enabling testing of urine in patients presenting to health care facilities in which lumbar puncture, or even blood sampling, is not feasible

    Do parkinsonian patients have trouble telling lies? The neurobiological basis of deceptive behaviour

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    Parkinson's disease is a common neurodegenerative disorder with both motor symptoms and cognitive deficits such as executive dysfunction. Over the past 100 years, a growing body of literature has suggested that patients with Parkinson's disease have characteristic personality traits such as industriousness, seriousness and inflexibility. They have also been described as ‘honest’, indicating that they have a tendency not to deceive others. However, these personality traits may actually be associated with dysfunction of specific brain regions affected by the disease. In the present study, we show that patients with Parkinson's disease are indeed ‘honest’, and that this personality trait might be derived from dysfunction of the prefrontal cortex. Using a novel cognitive task, we confirmed that patients with Parkinson's disease (n = 32) had difficulty making deceptive responses relative to healthy controls (n = 20). Also, using resting-state 18F-fluorodeoxyglucose PET, we showed that this difficulty was significantly correlated with prefrontal hypometabolism. Our results are the first to demonstrate that the ostensible honesty found in patients with Parkinson's disease has a neurobiological basis, and they provide direct neuropsychological evidence of the brain mechanisms crucial for human deceptive behaviour
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