95,954 research outputs found

    Communications

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    Learning on the Halfshell

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    Approximating C1,0C^{1,0}-foliations

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    We extend the Eliashberg-Thurston theorem on approximations of taut oriented C2C^2-foliations of 3-manifolds by both positive and negative contact structures to a large class of taut oriented C1,0C^{1,0}-foliations, where by C1,0C^{1,0} foliation, we mean a foliation with continuous tangent plane field. These C1,0C^{1,0}-foliations can therefore be approximated by weakly symplectically fillable, universally tight, contact structures. This allows applications of C2C^2-foliation theory to contact topology and Floer theory to be generalized and extended to constructions of C1,0C^{1,0}-foliations.Comment: 52 pages, 5 figures. Final version with updated references, corrections and terminolog

    Exposing the dressed quark's mass

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    This snapshot of recent progress in hadron physics made in connection with QCD's Dyson-Schwinger equations includes: a perspective on confinement and dynamical chiral symmetry breaking (DCSB); a pre'cis on the physics of in-hadron condensates; results on the hadron spectrum, including dressed-quark-core masses for the nucleon and Delta, their first radial excitations, and the parity-partners of these states; an illustration of the impact of DCSB on the electromagnetic pion form factor, thereby exemplifying how data can be used to chart the momentum-dependence of the dressed-quark mass function; and a prediction that F_1^{p,d}/F_1^{p,u} passes through zero at Q^2\approx 5m_N^2 owing to the presence of nonpointlike scalar and axial-vector diquark correlations in the nucleon.Comment: 10 pages, 4 figures, 2 tables. Contribution to the Proceedings of the 4th Workshop on Exclusive Reactions at High Momentum Transfer, Thomas Jefferson National Accelerator Facility Newport News, Virginia, 18-21 May 201

    Motion in a Bose condensate: IX. Crow instability of antiparallel vortex pairs

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    The Gross-Pitaevskii (GP) equation admits a two-dimensional solitary wave solution representing two mutually self-propelled, anti-parallel straight line vortices. The complete sequence of such solitary wave solutions has been computed by Jones and Roberts (J. Phys. A, 15, 2599, 1982). These solutions are unstable with respect to three-dimensional perturbations (the Crow instability). The most unstable mode has a wavelength along the direction of the vortices of the same order as their separation. The growth rate associated with this mode is evaluated here, and it is found to increase very rapidly with decreasing separation. It is shown, through numerical integrations of the GP equation that, as the perturbations grow to finite amplitude, the lines reconnect to produce a sequence of almost circular vortex rings.Comment: Submitted to J. Phys. A: Math. Gen.; Corrected reference

    Going the same 'weigh': spousal correlations in obesity in the UK

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    The obesity epidemic has received widespread media and research attention. However, the social phenomenon of obesity is still not well understood. Data from the 2004 and 2006 waves of the British Household Panel Survey (BHPS) show positive and significant correlations in spousal body mass index (BMI). This paper explores three mechanisms of shared individual characteristics, social influence and shared environment to explain this correlation. A number of econometric specifications are used to investigate the role of observed individual characteristics, own health, spouse health, social influence, contextual effects and unobserved individual effects on the influence of these three hypotheses on the correlation in spousal BMI. Results indicate that social influence and shared individual characteristics, which may arise through assortative matching, both contribute to correlation in spousal BMI

    An approach to market analysis for lighter than air transportation of freight

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    An approach is presented to marketing analysis for lighter than air vehicles in a commercial freight market. After a discussion of key characteristics of supply and demand factors, a three-phase approach to marketing analysis is described. The existing transportation systems are quantitatively defined and possible roles for lighter than air vehicles within this framework are postulated. The marketing analysis views the situation from the perspective of both the shipper and the carrier. A demand for freight service is assumed and the resulting supply characteristics are determined. Then, these supply characteristics are used to establish the demand for competing modes. The process is then iterated to arrive at the market solution

    Cardiovascular Effects of Vibration Semiannual Report, 1 Aug. 1965 - 28 Feb. 1966

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    Vibration induced cardiovascular changes in anesthetized dog
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