318 research outputs found

    The freshwater jellyfish Craspedacusta sowerbii Lankester, 1880 (Limnomedusa: Olindiidae) in Germany, with a brief note on its nomenclature

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    The freshwater jellyfish Craspedacusta sowerbii Lankester is distributed worldwide in temperate, freshwater habitats. However, such a successful, worldwide dispersion of the medusa and its minute, less obvious polyp is unique among the freshwater jellyfish species (Limnomedusae, Olinidiae). Although numerous reports were given shortly after its discovery, the interest did not cease over the years. In cooperation with the German Underwater Federation (Verband Deutscher Sporttaucher e. V.) additional data of freshwater jellyfish occurrences could be obtained. In combination with previously published discovery reports, these data provide an area- wide observation of the distribution of freshwater jellyfish within the Federal Republic of Germany, adding 21 to the previously known C. sowerbii locations. Indications are that there is a far more wide spread distribution of the medusa than thought and the potentially even wider distribution of the often times overlooked polyp

    A natural renormalizable model of metastable SUSY breaking

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    We propose a model of metastable dynamical supersymmetry breaking in which all scales are generated dynamically. Our construction is a simple variant of the Intriligator-Seiberg-Shih model, with quark masses induced by renormalizable couplings to an auxiliary supersymmetric QCD sector. Since all scales arise from dimensional transmutation, the model has no fundamental dimensionful parameters. It also does not rely on higher-dimensional operators.Comment: 9 pages; v2: typos correcte

    Holographic metastability

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    We show how supersymmetric QCD in a slice of AdS can naturally acquire metastable vacua. The formulation closely follows that of Intriligator, Seiberg and Shih (ISS), with an "electric" sector on the UV brane and a "magnetic" sector on the IR brane. However the 't Hooft anomaly matching that constrains the Seiberg duality central to ISS is replaced by anomaly inflow and cancellation, and the source of strong coupling is the CFT to which the theory couples rather than the gauge groups. The theory contains an anomaly free R-symmetry that, when broken by UV effects, leads to an O'Raifeartaigh model on the IR brane. In contrast to ISS, the R-symmetry breaking in the UV can be maximal, and yet the R-symmetry breaking in the IR theory remains under strict control: there is no need for retrofitting of small parameters.Comment: 20 pages, 2 figure

    Cultivation-Independent Analysis of the Bacterial Community Associated With the Calcareous Sponge Clathrina clathrus and Isolation of Poriferisphaera corsica Gen. Nov., Sp. Nov., Belonging to the Barely Studied Class Phycisphaerae in the Phylum Planctomycetes

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    Marine ecosystems serve as global carbon sinks and nutrient source or breeding ground for aquatic animals. Sponges are ancient parts of these important ecosystems and can be found in caves, the deep-sea, clear waters, or more turbid environments. Here, we studied the bacterial community composition of the calcareous sponge Clathrina clathrus sampled close to the island Corsica in the Mediterranean Sea with an emphasis on planctomycetes. We show that the phylum Planctomycetes accounts for 9% of the C. clathrus-associated bacterial community, a 5-fold enrichment compared to the surrounding seawater. Indeed, the use of C. clathrus as a yet untapped source of novel planctomycetal strains led to the isolation of strain KS4T. The strain represents a novel genus and species within the class Phycisphaerae in the phylum Planctomycetes and displays interesting cell biological features, such as formation of outer membrane vesicles and an unexpected mode of cell division

    Physics at the e+ e- Linear Collider

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    A comprehensive review of physics at an e+e- Linear Collider in the energy range of sqrt{s}=92 GeV--3 TeV is presented in view of recent and expected LHC results, experiments from low energy as well as astroparticle physics.The report focuses in particular on Higgs boson, Top quark and electroweak precision physics, but also discusses several models of beyond the Standard Model physics such as Supersymmetry, little Higgs models and extra gauge bosons. The connection to cosmology has been analyzed as well.Comment: 179 pages, plots and references updated, version to be published at EPJ

    Theory and Applications of X-ray Standing Waves in Real Crystals

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    Theoretical aspects of x-ray standing wave method for investigation of the real structure of crystals are considered in this review paper. Starting from the general approach of the secondary radiation yield from deformed crystals this theory is applied to different concreat cases. Various models of deformed crystals like: bicrystal model, multilayer model, crystals with extended deformation field are considered in detailes. Peculiarities of x-ray standing wave behavior in different scattering geometries (Bragg, Laue) are analysed in detailes. New possibilities to solve the phase problem with x-ray standing wave method are discussed in the review. General theoretical approaches are illustrated with a big number of experimental results.Comment: 101 pages, 43 figures, 3 table

    An NLO QCD analysis of inclusive cross-section and jet-production data from the ZEUS experiment

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    The ZEUS inclusive differential cross-section data from HERA, for charged and neutral current processes taken with e+ and e- beams, together with differential cross-section data on inclusive jet production in e+ p scattering and dijet production in \gamma p scattering, have been used in a new NLO QCD analysis to extract the parton distribution functions of the proton. The input of jet data constrains the gluon and allows an accurate extraction of \alpha_s(M_Z) at NLO; \alpha_s(M_Z) = 0.1183 \pm 0.0028(exp.) \pm 0.0008(model) An additional uncertainty from the choice of scales is estimated as \pm 0.005. This is the first extraction of \alpha_s(M_Z) from HERA data alone.Comment: 37 pages, 14 figures, to be submitted to EPJC. PDFs available at http://durpdg.dur.ac.uk/hepdata in LHAPDFv
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