54,755 research outputs found

    What is an epitheliome, anyway?

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    Look right! A retrospective study of pedestrian accidents involving overseas visitors to London

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    Introduction: Research within the European Union has shown international visitors to have a higher injury mortality than residents. Traffic accidents are the leading cause of injury-related death among overseas visitors and evidence suggests overseas visitors are at a greater risk of being involved in road traffic accidents than the resident population. Little information looks specifically at pedestrian injuries to overseas visitors. Pedestrian deaths account for 21% of all UK road deaths. Methods: A retrospective database review of London helicopter emergency medical service (HEMS) missions was undertaken to examine the number and type of missions to overseas visitors, specifically examining pedestrian incidents. Results: Of 121 missions to overseas visitors, 74 (61%) involved the visitor as a pedestrian struck by a vehicle. Thirty-five pedestrians (47%) were struck by a bus and 20 by a car (27%). Fourteen patients (19%) had an initial Glasgow coma scale score of 3–8, suggesting severe head injury and half of all patients required prehospital intubation (38/74, 51%). Mortality was 16% (12/74%) and 62 patients (84%) survived to hospital discharge. Of 39 patients admitted to the Royal London Hospital, the average injury severity score (ISS%) was 23.0 (ISS >15 denotes severe trauma) with a mean inpatient stay of 17.9 days. Conclusion: During the 7-year period studied, 61% of HEMS missions to overseas visitors involved a pedestrian being struck by a vehicle, compared with 16% of missions to UK residents. For HEMS missions, serious trauma to pedestrians is disproportionally more common among the visitor population to London

    Quarkonium spin structure in lattice NRQCD

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    Numerical simulations of the quarkonium spin splittings are done in the framework of lattice nonrelativistic quantum chromodynamics (NRQCD). At leading order in the velocity expansion the spin splittings are of O(MQv4)O(M_Q v^4), where MQM_Q is the renormalized quark mass and v2v^2 is the mean squared quark velocity. A systematic analysis is done of all next-to-leading order corrections. This includes the addition of O(MQv6)O(M_Q v^6) relativistic interactions, and the removal of O(a2MQv4)O(a^2 M_Q v^4) discretization errors in the leading-order interactions. Simulations are done for both S- and P-wave mesons, with a variety of heavy quark actions and over a wide range of lattice spacings. Two prescriptions for the tadpole improvement of the action are also studied in detail: one using the measured value of the average plaquette, the other using the mean link measured in Landau gauge. Next-to-leading order interactions result in a very large reduction in the charmonium splittings, down by about 60% from their values at leading order. There are further indications that the velocity expansion may be poorly convergent for charmonium. Prelimary results show a small correction to the hyperfine splitting in the Upsilon system.Comment: 16 pages, REVTEX v3.1, 5 postscript figures include

    Tadpole renormalization and relativistic corrections in lattice NRQCD

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    We make a comparison of two tadpole renormalization schemes in the context of the quarkonium hyperfine splittings in lattice NRQCD. Improved gauge-field and NRQCD actions are analyzed using the mean-link u0,Lu_{0,L} in Landau gauge, and using the fourth root of the average plaquette u0,Pu_{0,P}. Simulations are done for ccˉc\bar c, bcˉb\bar c, and bbˉb\bar b systems. The hyperfine splittings are computed both at leading and at next-to-leading order in the relativistic expansion. Results are obtained at lattice spacings in the range of about 0.14~fm to 0.38~fm. A number of features emerge, all of which favor tadpole renormalization using u0,Lu_{0,L}. This includes much better scaling behavior of the hyperfine splittings in the three quarkonium systems when u0,Lu_{0,L} is used. We also find that relativistic corrections to the spin splittings are smaller when u0,Lu_{0,L} is used, particularly for the ccˉc\bar c and bcˉb\bar c systems. We also see signs of a breakdown in the NRQCD expansion when the bare quark mass falls below about one in lattice units. Simulations with u0,Lu_{0,L} also appear to be better behaved in this context: the bare quark masses turn out to be larger when u0,Lu_{0,L} is used, compared to when u0,Pu_{0,P} is used on lattices with comparable spacings. These results also demonstrate the need to go beyond tree-level tadpole improvement for precision simulations.Comment: 14 pages, 7 figures (minor changes to some phraseology and references

    Precision Charmonium Spectroscopy From Lattice QCD

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    We present results for Charmonium spectroscopy using Non-Relativistic QCD (NRQCD). For the NRQCD action the leading order spin-dependent and next to leading order spin-independent interactions have been included with tadpole-improved coefficients. We use multi-exponential fits to multiple correlation functions to extract ground and excited SS states. Splittings between the lowest SS, PP and DD states are given and we have accurate values for the SS state hyperfine splitting and the χc\chi_c fine structure. Agreement with experiment is good - the remaining systematic errors are discussed.Comment: 23 pages uuencoded latex file. Contains figures in late

    NRQCD results on the MILC extra coarse ensemble

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    We present preliminary results using NRQCD to describe heavy quarks on the MILC 2+1 flavour dynamical extra coarse ensemble. We calculate the spectra of low lying states in bottomonium to complement earlier results on the finer MILC ensembles. We then exploit the coarseness of the lattices to calculate charm propagators using NRQCD. These are used to examine the charmonium spectrum and to calclate the mass of the BcB_c using NRQCD. Finally we look breifly at the BdB_d and BsB_s systems using the imporoved staggered formalism to describe the light valence quarks.Comment: 6 pages, Talk presented at Lattice 2005 (Heavy Quarks), Dublin, 25-30 July 200

    BB and BcB_c mesons with NRQCD and Clover actions

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    We present preliminary results from our study of the heavy-light spectrum and decay constants. For the heavy quark, we use NRQCD at various masses around and above the bb quark mass. For the first time, the heavy quark action and the heavy-light current consistently include corrections at second order in the non-relativistic expansion, as well as the leading finite aa corrections. The light quarks are simulated using a tadpole-improved Clover action at various masses in the strange and cc quark region.Comment: 6 Pages LaTex. Axis files of figures included. Joint writeup of two talks presented at LATTICE96(heavy quarks
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