7,634 research outputs found

    Simultaneous Kummer congruences and E\mathbb{E}_\infty-orientations of KO and tmf

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    Building on results of M. Ando, M.J. Hopkins and C. Rezk, we show the existence of uncountably many E\mathbb{E}_\infty-String orientations of real K-theory KO and of topological modular forms tmf, generalizing the A^\hat{A}- (resp. the Witten) genus. Furthermore, the obstruction to lifting an E\mathbb{E}_\infty-String orientations from KO to tmf is identified with a classical Iwasawa-theoretic condition. The common key to all these results is a precise understanding of the classical Kummer congruences, imposed for all primes simultaneously. This result is of independent arithmetic interest.Comment: final versio

    Reconstruction methods for acoustic particle detection in the deep sea using clusters of hydrophones

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    This article focuses on techniques for acoustic noise reduction, signal filters and source reconstruction. For noise reduction, bandpass filters and cross correlations are found to be efficient and fast ways to improve the signal to noise ratio and identify a possible neutrino-induced acoustic signal. The reconstruction of the position of an acoustic point source in the sea is performed by using small-volume clusters of hydrophones (about 1 cubic meter) for direction reconstruction by a beamforming algorithm. The directional information from a number of such clusters allows for position reconstruction. The algorithms for data filtering, direction and position reconstruction are explained and demonstrated using simulated data.Comment: 7 pages, 13 figure

    Contribution of the nucleon-hyperon reaction channels to K^- production in proton-nucleus collisions

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    The cross sections for producing K^- mesons in nucleon-hyperon elementary processes are estimated assuming one-pion exchange and using the experimentally known pion-hyperon cross sections. The results are implemented in a transport model which is applied to calculation of proton-nucleus collisions. In significant difference to earlier estimates for heavy-ion collisions the inclusion of the nucleon-hyperon cross section roughly doubles the K^- production in near-threshold proton-nucleus collisions

    Integration of Acoustic Neutrino Detection Methods into ANTARES

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    The ANTARES Neutrino Telescope is a water Cherenkov detector currently under construction in the Mediterranean Sea. It is also designed to serve as a platform for investigations of the deep-sea environment. In this context, the ANTARES group at the University of Erlangen will integrate acoustic sensors within the infrastructure of the experiment. With this dedicated setup, tests of acoustic particle detection methods and deep-sea acoustic background studies shall be performed. The aim of this project is to evaluate the feasibility of a future acoustic neutrino telescope in the deep sea operating in the ultra-high energy regime. In these proceedings, the implementation of the project is described in the context of the premises and challenges set by the physics of acoustic particle detection and the integration into an existing infrastructure.Comment: 6 pages, 5 figures, to appear in the proceedings of the International ARENA Workshop, May 28-30th, 2006, University of Northumbri

    Measurement of pH. Definition, Standards, and Procedures

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    The definition of a “primary method of measurement” [1] has permitted a full consideration of the definition of primary standards for pH, determined by a primary method (cell without transference, Harned cell), of the definition of secondary standards by secondary methods, and of the question whether pH, as a conventional quantity, can be incorporated within the internationally accepted system of measurement, the International System of Units (SI, Système International d’Unités). This approach has enabled resolution of the previous compromise IUPAC 1985 Recommendations [2]. Furthermore, incorporation of the uncertainties for the primary method, and for all subsequent measurements, permits the uncertainties for all procedures to be linked to the primary standards by an unbroken chain of comparisons. Thus, a rational choice can be made by the analyst of the appropriate procedure to achieve the target uncertainty of sample pH. Accordingly, this document explains IUPAC recommended definitions, procedures, and terminology relating to pH measurements in dilute aqueous solutions in the temperature range 5–50 °C. Details are given of the primary and secondary methods for measuring pH and the rationale for the assignment of pH values with appropriate uncertainties to selected primary and secondary substances

    Identification of novel Cyclooxygenase-2-dependent genes in Helicobacter pylori infection in vivo

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    <p>Abstract</p> <p>Background</p> <p><it>Helicobacter pylori </it>is a crucial determining factor in the pathogenesis of benign and neoplastic gastric diseases. Cyclooxygenase-2 (Cox-2) is the inducible key enzyme of arachidonic acid metabolism and is a central mediator in inflammation and cancer. Expression of the <it>Cox-2 </it>gene is up-regulated in the gastric mucosa during <it>H. pylori </it>infection but the pathobiological consequences of this enhanced Cox-2 expression are not yet characterized. The aim of this study was to identify novel genes down-stream of Cox-2 in an <it>in vivo </it>model, thereby identifying potential targets for the study of the role of Cox- 2 in <it>H. pylori </it>pathogenesis and the initiation of pre- cancerous changes.</p> <p>Results</p> <p>Gene expression profiles in the gastric mucosa of mice treated with a specific Cox-2 inhibitor (NS398) or vehicle were analysed at different time points (6, 13 and 19 wk) after <it>H. pylori </it>infection. <it>H. pylori </it>infection affected the expression of 385 genes over the experimental period, including regulators of gastric physiology, proliferation, apoptosis and mucosal defence. Under conditions of Cox-2 inhibition, 160 target genes were regulated as a result of <it>H. pylori </it>infection. The Cox-2 dependent subset included those influencing gastric physiology (<it>Gastrin, Galr1</it>), epithelial barrier function (<it>Tjp1, connexin45, Aqp5</it>), inflammation (<it>Icam1</it>), apoptosis (<it>Clu</it>) and proliferation (<it>Gdf3, Igf2</it>). Treatment with NS398 alone caused differential expression of 140 genes, 97 of which were unique, indicating that these genes are regulated under conditions of basal Cox-2 expression.</p> <p>Conclusion</p> <p>This study has identified a panel of novel Cox-2 dependent genes influenced under both normal and the inflammatory conditions induced by <it>H. pylori </it>infection. These data provide important new links between Cox-2 and inflammatory processes, epithelial repair and integrity.</p
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