1,163 research outputs found

    On the asymptotic magnitude of subsets of Euclidean space

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    Magnitude is a canonical invariant of finite metric spaces which has its origins in category theory; it is analogous to cardinality of finite sets. Here, by approximating certain compact subsets of Euclidean space with finite subsets, the magnitudes of line segments, circles and Cantor sets are defined and calculated. It is observed that asymptotically these satisfy the inclusion-exclusion principle, relating them to intrinsic volumes of polyconvex sets.Comment: 23 pages. Version 2: updated to reflect more recent work, in particular, the approximation method is now known to calculate (rather than merely define) the magnitude; also minor alterations such as references adde

    Electronic structure and superconductivity of Europium

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    We have calculated the electronic structure of Eu for the bcc, hcp, and fcc crystal structures for volumes near equilibrium up to a calculated 90 GPa pressure using the augmented-plane wave method in the local-density approximation. The frozen-core approximation was used with a semi-empirical shift of the f-states energies in the radial Schro¨\ddot{o}dinger equation to move the occupied 4f valence states below the Γ1\Gamma_1 energy and into the core. This shift of the highly localized f-states yields the correct europium phase ordering with lattice parameters and bulk moduli in good agreement with experimental data. The calculated superconductivity properties under pressure for the bcc\it bcc and hcp\it hcp structures are also found to agree with and follow a TcT_c trend similar to recent measurement by Debessai et al.1^1Comment: 8 page

    Introduction to tandem mirror physics

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    Neutral top-pion and lepton flavor violating processes

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    In the context of topcolor-assisted techicolor(TC2) models, we study the contributions of the neutral top-pion πt0\pi^{0}_{t} to the lepton flavor violating(LFV) processes liljγl_{i}\to l_{j}\gamma and liljlklll_{i}\to l_{j}l_{k}l_{l}. We find that the present experimental bound on μeγ\mu\to e\gamma gives severe constraints on the free parameters of TC2TC2 models. Taking into account these constraints, we consider the processes liljlklll_{i}\to l_{j}l_{k}l_{l} generated by top-pion exchange at the tree-level and the one loop level, and obtain Br(μ3e)2.87×1014Br(\mu\to 3e)\simeq 2.87\times 10^{-14}, 1.1×1015Br(τ3e)Br(τ2eμ)4.4×10151.1\times 10^{-15}\leq Br(\tau\to 3e)\simeq Br(\tau\to 2e\mu)\leq 4.4 \times 10^{-15} , 3.1×1015Br(τ2μe)Br(τ3μ)1.5×10143.1\times 10^{-15} \leq Br(\tau\to 2\mu e)\simeq Br(\tau\to 3\mu)\leq 1.5 \times 10^{-14} in most of the parameter space.Comment: latex files,16 pages, 6 figures. Submitted to Phys. Rev.

    Non-commutative desingularization of determinantal varieties, I

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    We show that determinantal varieties defined by maximal minors of a generic matrix have a non-commutative desingularization, in that we construct a maximal Cohen-Macaulay module over such a variety whose endomorphism ring is Cohen-Macaulay and has finite global dimension. In the case of the determinant of a square matrix, this gives a non-commutative crepant resolution.Comment: 52 pages, 3 figures, all comments welcom

    The institutional shaping of management: in the tracks of English individualism

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    Globalisation raises important questions about the shaping of economic action by cultural factors. This article explores the formation of what is seen by some as a prime influence on the formation of British management: individualism. Drawing on a range of historical sources, it argues for a comparative approach. In this case, the primary comparison drawn is between England and Scotland. The contention is that there is a systemic approach to authority in Scotland that can be contrasted to a personal approach in England. An examination of the careers of a number of Scottish pioneers of management suggests the roots of this systemic approach in practices of church governance. Ultimately this systemic approach was to take a secondary role to the personal approach engendered by institutions like the universities of Oxford and Cambridge, but it found more success in the different institutional context of the USA. The complexities of dealing with historical evidence are stressed, as is the value of taking a comparative approach. In this case this indicates a need to take religious practice as seriously as religious belief as a source of transferable practice. The article suggests that management should not be seen as a simple response to economic imperatives, but as shaped by the social and cultural context from which it emerges

    Autoantibodies against EPCR are found in antiphospholipid syndrome and are a risk factor for fetal death

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    The antiphospholipid syndrome (APS) is associated with thrombosis and fetal death but the pathologic mechanisms are poorly understood. Since endothelial protein C receptor (EPCR) plays a role in the anticoagulant system and in placental development, we hypothesized that anti-EPCR autoantibodies may be involved in clinical manifestations of APS and in fetal loss. The levels of immunoglobulin M (IgM) and IgG anti-EPCR autoantibodies were analyzed by enzyme-linked immunosorbent assay (ELISA) in 43 patients with APS and 43 controls. Anti-EPCR levels were higher in APS patients than in controls. Interestingly, one of the IgM anti-EPCR autoantibodies inhibited the generation of activated protein C on endothelium. Since markedly high anti-EPCR levels were found in women with fetal death, 87 patients with a first episode of unexplained fetal death were subsequently analyzed and their anti-EPCR levels were compared with 87 matched controls. We found that anti-EPCR autoantibodies constitute an independent risk factor for a first fetal death episode: the adjusted odds ratios (ORs) for anti-EPCR autoantibodies above the 95th percentile were 23.0 (95% confidence interval [CI], 2.0-266.3) for IgM and 6.8 (95% CI, 1.2-38.4) for IgG. Anti-EPCR autoantibodies can be detected in APS patients and are independent risk factors for fetal death

    Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

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    A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

    Measurement of D*+/- meson production in jets from pp collisions at sqrt(s) = 7 TeV with the ATLAS detector

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    This paper reports a measurement of D*+/- meson production in jets from proton-proton collisions at a center-of-mass energy of sqrt(s) = 7 TeV at the CERN Large Hadron Collider. The measurement is based on a data sample recorded with the ATLAS detector with an integrated luminosity of 0.30 pb^-1 for jets with transverse momentum between 25 and 70 GeV in the pseudorapidity range |eta| < 2.5. D*+/- mesons found in jets are fully reconstructed in the decay chain: D*+ -> D0pi+, D0 -> K-pi+, and its charge conjugate. The production rate is found to be N(D*+/-)/N(jet) = 0.025 +/- 0.001(stat.) +/- 0.004(syst.) for D*+/- mesons that carry a fraction z of the jet momentum in the range 0.3 < z < 1. Monte Carlo predictions fail to describe the data at small values of z, and this is most marked at low jet transverse momentum.Comment: 10 pages plus author list (22 pages total), 5 figures, 1 table, matches published version in Physical Review

    Search for the Invisible Decay of Neutrons with KamLAND

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    The Kamioka Liquid scintillator Anti-Neutrino Detector (KamLAND) is used in a search for single neutron or two neutron intra-nuclear disappearance that would produce holes in the s\it{s}-shell energy level of 12^{12}C nuclei. Such holes could be created as a result of nucleon decay into invisible modes (invinv), e.g. n3νn \to 3\nu or nn2νnn \to 2\nu. The de-excitation of the corresponding daughter nucleus results in a sequence of space and time correlated events observable in the liquid scintillator detector. We report on new limits for one- and two-neutron disappearance: τ(ninv)>5.8×1029\tau(n\to inv)> 5.8\times 10^{29} years and τ(nninv)>1.4×1030\tau (nn \to inv)> 1.4 \times 10^{30} years at 90% CL. These results represent an improvement of factors of \sim3 and >104>10^4 over previous experiments.Comment: 5 pages, 3 figure
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