19,665 research outputs found

    The return of the bursts: Thermonuclear flashes from Circinus X-1

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    We report the detection of 15 X-ray bursts with RXTE and Swift observations of the peculiar X-ray binary Circinus X-1 during its May 2010 X-ray re-brightening. These are the first X-ray bursts observed from the source after the initial discovery by Tennant and collaborators, twenty-five years ago. By studying their spectral evolution, we firmly identify nine of the bursts as type I (thermonuclear) X-ray bursts. We obtain an arcsecond location of the bursts that confirms once and for all the identification of Cir X-1 as a type I X-ray burst source, and therefore as a low magnetic field accreting neutron star. The first five bursts observed by RXTE are weak and show approximately symmetric light curves, without detectable signs of cooling along the burst decay. We discuss their possible nature. Finally, we explore a scenario to explain why Cir X-1 shows thermonuclear bursts now but not in the past, when it was extensively observed and accreting at a similar rate.Comment: Accepted for publication in The Astrophysical Journal Letters. Tables 1 & 2 merged. Minor changes after referee's comments. 5 pages, 4 Figure

    Dirac operators and the Very Strange Formula for Lie superalgebras

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    Using a super-affine version of Kostant's cubic Dirac operator, we prove a very strange formula for quadratic finite-dimensional Lie superalgebras with a reductive even subalgebra.Comment: Latex file, 25 pages. A few misprints corrected. To appear in the forthcoming volume "Advances in Lie Superalgebras", Springer INdAM Serie

    Effect of substrate surface topography on forensic development of latent fingerprints with iron oxide powder suspension

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    This is a pre-print version of the article. The official published version can be accessed from the link below - Copyright @ 2010 Wiley-BlackwellLatent fingerprint deposition and effectiveness of detection are strongly affected by the surface on which prints are deposited. Material properties, surface roughness, morphology, chemistry and hydrophobicity can affect the usefulness or efficacy of forensic print development techniques. Established protocols outline appropriate techniques and sequences of processes for broad categories of operational surfaces. This study uses atomic force microscopy and scanning electron microscopy to investigate a series of surfaces classified as smooth, non-porous plastic. Latent prints developed with iron oxide powder suspension are analysed on a range of scales from macro to nano to help elucidate the interaction mechanisms between the latent fingerprint, development agent and underlying surface. Differences between surfaces have a strong effect, even within this single category. We show that both average roughness and topographical feature shape, characterised by skew, kurtosis and lay, are important factors to consider for the processing of latent fingerprints. Copyright (C) 2010 John Wiley & Sons, Ltd.This work is part-funded by the UK Home Office project 7088762

    Euclidean TSP with few inner points in linear space

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    Given a set of nn points in the Euclidean plane, such that just kk points are strictly inside the convex hull of the whole set, we want to find the shortest tour visiting every point. The fastest known algorithm for the version when kk is significantly smaller than nn, i.e., when there are just few inner points, works in O(k11kk1.5n3)O(k^{11\sqrt{k}} k^{1.5} n^{3}) time [Knauer and Spillner, WG 2006], but also requires space of order kckn2k^{c\sqrt{k}}n^{2}. The best linear space algorithm takes O(k!kn)O(k! k n) time [Deineko, Hoffmann, Okamoto, Woeginer, Oper. Res. Lett. 34(1), 106-110]. We construct a linear space O(nk2+kO(k))O(nk^2+k^{O(\sqrt{k})}) time algorithm. The new insight is extending the known divide-and-conquer method based on planar separators with a matching-based argument to shrink the instance in every recursive call. This argument also shows that the problem admits a quadratic bikernel.Comment: under submissio

    Interrogating narratives of heritage in place

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    In South Westland, New Zealand, despite the remoteness of its relatively intact and diverse geomorphic and biophysical systems, social and cultural values are significant. These values, however, are not recognised in its designation as a world heritage area. This paper uses narratives from different sources and an interrogative process, to reveal not only a range of approaches to heritage, expressed or implied by different stakeholder groups, but also the paradoxical nature of interrelationships among people, place and heritage. It allows tentative conclusions to be made about the significance of the lack of an explicit management strategy for the world heritage area as a whole, and about the need for heritage, whether regarded instrumentally as natural or cultural, to be reconceptualised as a cultural construct

    Equivariant map superalgebras

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    Suppose a group Γ\Gamma acts on a scheme XX and a Lie superalgebra g\mathfrak{g}. The corresponding equivariant map superalgebra is the Lie superalgebra of equivariant regular maps from XX to g\mathfrak{g}. We classify the irreducible finite dimensional modules for these superalgebras under the assumptions that the coordinate ring of XX is finitely generated, Γ\Gamma is finite abelian and acts freely on the rational points of XX, and g\mathfrak{g} is a basic classical Lie superalgebra (or sl(n,n)\mathfrak{sl}(n,n), n>0n > 0, if Γ\Gamma is trivial). We show that they are all (tensor products of) generalized evaluation modules and are parameterized by a certain set of equivariant finitely supported maps defined on XX. Furthermore, in the case that the even part of g\mathfrak{g} is semisimple, we show that all such modules are in fact (tensor products of) evaluation modules. On the other hand, if the even part of g\mathfrak{g} is not semisimple (more generally, if g\mathfrak{g} is of type I), we introduce a natural generalization of Kac modules and show that all irreducible finite dimensional modules are quotients of these. As a special case, our results give the first classification of the irreducible finite dimensional modules for twisted loop superalgebras.Comment: 27 pages. v2: Section numbering changed to match published version. Other minor corrections. v3: Minor corrections (see change log at end of introduction

    Proton-pump inhibitors

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    Proton-pump inhibitors (PPIs) are a class of drugs that profoundly suppress gastric acid secretion, and thus have become the treatment of choice for gastro-oesophageal reflux disease and peptic ulcer disease. PPIs are considered safe and effective. It is essential that clinicians understand the appropriate use of PPIs, given the significant economic burden of inappropriate prescribing and safety concerns. Long-term safety concerns and possible drug interactions have led to a more conservative approach to PPI use. Some of these concerns may have been overstated, but they serve to highlight the need for ongoing vigilance because even a small increased risk of an adverse event may translate to a large number, considering that the use of PPIs is widespread. This review focuses on the use of oral PPIs in the ambulatory setting, and recent concerns regarding the adverse effects of PPIs.Keywords: proton-pump inhibitors, PPIs, gastro-oeseophageal reflux disease, GORD, PU

    CANDIDATE GENES ASSOCIATED WITH POLYCYSTIC OVARY SYNDROME IN ASIAN POPULATIONS: A RESEARCH REVIEW

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    Polycystic ovary syndrome (PCOS) is a complex genetic condition and is a highly prevalent heterogeneous syndrome of clinical and biochemicalandrogen excess. The disease has genetic as well as environmental involvements. The normal menstrual cycle results from a coordination of hormonal secretion and signaling within the hypothalamic pituitary-ovarian axis. Alterations in the normal cycle or irregularity in menstrual cycle result inamenorrhea, abnormal uterine bleeding, etc. The main causes are PCOS, hormonal imbalance, drugs, nutritional deficiency, personality, some geneticfactors, and many more. Women with PCOS are often resistant to the biological effects of insulin and, as a consequence, may have high insulin levels. Women with PCOS are at risk for type 2 diabetes, high cholesterol, and high blood pressure. Obesity also appears to worsen the condition. The impactof the syndrome on an individual varies significantly based on several factors such as the severity of the components, comorbidities, and life courseconsiderations. In addition, each individual experiences the syndrome in the context of her own reproductive health, metabolic, and quality-of-lifeconcerns. Hirsutism, obesity, and infertility are common complaints. This review article gives a detailed account on the association of candidate genesassociated with PCOS in South Asian population.Keywords: Anti-mullerian hormone, Growth/differentiation factor 9, The bone morphogenetic protein, Follicle-stimulating hormone, Follistatin,Cytochrome p450, Polymerase chain reaction-restriction fragment length polymorphism

    Effective unidirectional pumping for steady-state amplification without inversion

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    We discuss an opportunity to achieve amplification without inversion in three-level cascade scheme using an effective unidirectional pumping via bidirectional incoherent pump. Analytical solution to the population and the coherence are obtained in the steady-state regime. With a proper choice of the parameters, obtained here, the possibility for amplification without inversion is presented.Comment: 8 Pages, 7 figure
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