44,008 research outputs found

    Improving the performance of swift-water rescue quick release harnesses

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    This paper considered the effectiveness of empathic design modifications to quick release harness design. It was found that the critical element in effecting a rapid and efficient release was the tape length distal to the buckle/back-bar components. We have concluded that the length of tape pulled through the buckle and the loading of the buckle/ tri-glide are critical to ensure an effective release. Physical separation of tape and buckle mechanism when the harness is released is crucial to the effective release. We then considered the problems this may pose in multiple user situations such as ‘call out’ teams or training use and we propose that the adaptation utilised in the research harness to facilitate testing may provide a simple and low cost solution to the multiple user problem allowing easy adjustment of the harness to ensure the separation of buckle and tape on release. We conclude by outlining the design adaptations and recommendations for the training and use of the quick release harness and make recommendations for the training of QRH use

    The Role of Linguistics Studies on the Political Debate

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    The paper is to find out the linguistics role contribution towards the political debate event at the election party. The presidential debate\u27s primary purpose is to sponsor and produce debates for the United States presidential and vice-presidential candidates and to undertake research and educational activities relating to the debates. A leaders\u27 debate or presidential debate is a public debate held during a general election campaign, where the candidates expose their political opinions and public policy proposals, and criticism of them, to potential voters. They are normally broadcast live on radio, television and the internet. Increasing learners\u27 confidence, poise, and self-esteem. Providing an engaging, active, learner-centered activity. Improving rigorous higher-order and critical thinking skills. Enhancing the ability to structure and organize thoughts

    Momentum Flow Correlations from Event Shapes: Factorized Soft Gluons and Soft-Collinear Effective Theory

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    The distributions of two-jet event shapes contain information on hadronization in QCD. Near the two-jet limit, these distributions can be described by convolutions of nonperturbative event shape functions with the same distributions calculated in resummed perturbation theory. The shape functions, in turn, are determined by correlations of momentum flow operators with each other and with light-like Wilson lines, which describe the coupling of soft, wide-angle radiation to jets. We observe that leading power corrections to the mean values of event shapes are determined by the correlation of a single momentum flow operator with the relevant Wilson lines. This generalizes arguments for the universality of leading power corrections based on the low-scale behavior of the running coupling or resummation. We also show how a study of the angularity event shapes can provide information on correlations involving multiple momentum flow operators, giving a window to the system of QCD dynamics that underlies the variety of event shape functions. In deriving these results, we review, develop and compare factorization techniques in conventional perturbative QCD and soft-collinear effective theory (SCET). We give special emphasis to the elimination of double counting of momentum regions in these two formalisms.Comment: 25 pages revtex

    All-Orders Singular Emission in Gauge Theories

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    I present a class of functions unifying all singular limits for the emission of soft or collinear gluons in gauge-theory amplitudes at any order in perturbation theory. Each function is a generalization of the antenna functions of ref. [1]. The helicity-summed interferences these functions are thereby also generalizations to higher orders of the Catani--Seymour dipole factorization function.Comment: 5 pages, 1 figur

    Fully Unintegrated Parton Correlation Functions and Factorization in Lowest Order Hard Scattering

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    Motivated by the need to correct the potentially large kinematic errors in approximations used in the standard formulation of perturbative QCD, we reformulate deeply inelastic lepton-proton scattering in terms of gauge invariant, universal parton correlation functions which depend on all components of parton four-momentum. Currently, different hard QCD processes are described by very different perturbative formalisms, each relying on its own set of kinematical approximations. In this paper we show how to set up formalism that avoids approximations on final-state momenta, and thus has a very general domain of applicability. The use of exact kinematics introduces a number of significant conceptual shifts already at leading order, and tightly constrains the formalism. We show how to define parton correlation functions that generalize the concepts of parton density, fragmentation function, and soft factor. After setting up a general subtraction formalism, we obtain a factorization theorem. To avoid complications with Ward identities the full derivation is restricted to abelian gauge theories; even so the resulting structure is highly suggestive of a similar treatment for non-abelian gauge theories.Comment: 44 pages, 69 figures typos fixed, clarifications and second appendix adde

    Next-to-Leading Order Hard Scattering Using Fully Unintegrated Parton Distribution Functions

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    We calculate the next-to-leading order fully unintegrated hard scattering coefficient for unpolarized gluon-induced deep inelastic scattering using the logical framework of parton correlation functions developed in previous work. In our approach, exact four-momentum conservation is maintained throughout the calculation. Hence, all non-perturbative functions, like parton distribution functions, depend on all components of parton four-momentum. In contrast to the usual collinear factorization approach where the hard scattering coefficient involves generalized functions (such as Dirac δ\delta-functions), the fully unintegrated hard scattering coefficient is an ordinary function. Gluon-induced deep inelastic scattering provides a simple illustration of the application of the fully unintegrated factorization formalism with a non-trivial hard scattering coefficient, applied to a phenomenologically interesting case. Furthermore, the gluon-induced process allows for a parameterization of the fully unintegrated gluon distribution function.Comment: 22 pages, Typos Fixed, Reference Added, Minor Clarification Adde

    Interference Fragmentation Functions and the Nucleon's Transversity

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    We introduce twist-two quark interference fragmentation functions in helicity density matrix formalism and study their physical implications. We show how the nucleon's transversity distribution can be probed through the final state interaction between two mesons (π+π−\pi^+\pi^-, KKˉK\bar K, or πK\pi K) produced in the current fragmentation region in deep inelastic scattering on a transversely polarized nucleon.Comment: Final version to be published in Phys. Rev. Let

    An imaging K-band survey - I: The catalogue, star and galaxy counts

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    We present results from a large area (552\,\sqamin) imaging KK-band survey to a 5σ\sigma limit of K≃17.3K\simeq 17.3. We have optical-infrared colours of almost all the objects in the sample. Star-galaxy discrimination is performed and the results used to derive the infrared star and galaxy counts. KK-band ``no-evolution'' galaxy-count models are constructed and compared with the observed data. In the infrared, there is no counterpart for the large excess of faint galaxies over the no-evolution model seen in optical counts. However, we show that the KK counts can be remarkably insensitive to evolution under certain reasonable assumptions. Finally, model predictions for KK-selected redshift surveys are derived.Comment: MNRAS in press. 21 pages plain TeX; figs plus table 4 available via anonymous ftp from /pub/kgb/paper1/sissa.uu at ftp.ast.cam.ac.u
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