464 research outputs found

    Charmonium spectroscopy and mixing with light quark and open charm states from nF=2 lattice QCD

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    We study the charmonium spectrum including higher spin and gluonic excitations. We determine an upper limit on the mixing of the eta_c ground state with light pseudoscalar flavour-singlet mesons and investigate the mixing of charmonia near open charm thresholds with pairs of (excited) D and anti-D mesons. For charm and light valence quarks and nF=2 sea quarks, we employ the non-perturbatively improved Sheikholeslami-Wohlert (clover) action. Excited states are accessed using the variational technique, starting from a basis of suitably optimised operators. For some aspects of this study, the use of improved stochastic all-to-all propagators was essential.Comment: 23 pages, v2: references updated, correction of an ambiguous statement, minor typos corrected, some figures update

    Charm quark system at the physical point of 2+1 flavor lattice QCD

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    We investigate the charm quark system using the relativistic heavy quark action on 2+1 flavor PACS-CS configurations previously generated on 323×6432^3 \times 64 lattice. The dynamical up-down and strange quark masses are set to the physical values by using the technique of reweighting to shift the quark hopping parameters from the values employed in the configuration generation. At the physical point, the lattice spacing equals a−1=2.194(10)a^{-1}=2.194(10) GeV and the spatial extent L=2.88(1)L=2.88(1) fm. The charm quark mass is determined by the spin-averaged mass of the 1S charmonium state, from which we obtain m_{\rm charm}^{\msbar}(\mu = m_{\rm charm}^{\msbar}) = 1.260(1)(6)(35) GeV, where the errors are due to our statistics, scale determination and renormalization factor. An additional systematic error from the heavy quark is of order αs2f(mQa)(aΛQCD)\alpha_s^2 f(m_Q a)(a \Lambda_{QCD}), which is estimated to be a percent level if the factor f(mQa)f(m_Q a) analytic in mQam_Q a is of order unity. Our results for the charmed and charmed-strange meson decay constants are fD=226(6)(1)(5)f_D=226(6)(1)(5) MeV, fDs=257(2)(1)(5)f_{D_s}=257(2)(1)(5) MeV, again up to the heavy quark errors of order αs2f(mQa)(aΛQCD)\alpha_s^2 f(m_Q a)(a \Lambda_{QCD}). Combined with the CLEO values for the leptonic decay widths, these values yield ∣Vcd∣=0.205(6)(1)(5)(9)|V_{cd}| = 0.205(6)(1)(5)(9), ∣Vcs∣=1.00(1)(1)(3)(3)|V_{cs}| = 1.00(1)(1)(3)(3), where the last error is on account of the experimental uncertainty of the decay widths.Comment: 16 pages, 12 figure

    Nucleotide sequence of cDNA encoding the precursor of the 23 kDa photosystem II protein of tomato

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43431/1/11103_2004_Article_BF00019216.pd

    Excitations of single-beauty hadrons

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    In this work we study the predominantly orbital and radial excitations of hadrons containing a single heavy quark. We present meson and baryon mass splittings and ratios of meson decay constants (e.g., fBs/fBf_{B_s}/f_B and fBsâ€Č/fBsf_{B_s'}/f_{B_s}) resulting from quenched and dynamical two-flavor configurations. Light quarks are simulated using the chirally improved (CI) lattice Dirac operator at valence masses as light as Mπ≈350M_\pi \approx 350 MeV. The heavy quark is approximated by a static propagator, appropriate for the bb quark on our lattices (1/a∌1−21/a \sim 1-2 GeV). We also include some preliminary calculations of the O(1/mQ)O(1/m_Q^{}) kinetic corrections to the states, showing, in the process, a viable way of applying the variational method to three-point functions involving excited states. We compare our results with recent experimental findings.Comment: 23 pages, 18 figures, 17 tables; slight title change (Ed. killjoy); reference added; version to appear in Phys Rev

    Core reconstruction in pseudopotential calculations

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    A new method is presented for obtaining all-electron results from a pseudopotential calculation. This is achieved by carrying out a localised calculation in the region of an atomic nucleus using the embedding potential method of Inglesfield [J.Phys. C {\bf 14}, 3795 (1981)]. In this method the core region is \emph{reconstructed}, and none of the simplifying approximations (such as spherical symmetry of the charge density/potential or frozen core electrons) that previous solutions to this problem have required are made. The embedding method requires an accurate real space Green function, and an analysis of the errors introduced in constructing this from a set of numerical eigenstates is given. Results are presented for an all-electron reconstruction of bulk aluminium, for both the charge density and the density of states.Comment: 14 pages, 5 figure

    Interatomic potentials for atomistic simulations of the Ti-Al system

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    Semi-empirical interatomic potentials have been developed for Al, alpha-Ti, and gamma-TiAl within the embedded atomic method (EAM) by fitting to a large database of experimental as well as ab-initio data. The ab-initio calculations were performed by the linear augmented plane wave (LAPW) method within the density functional theory to obtain the equations of state for a number of crystal structures of the Ti-Al system. Some of the calculated LAPW energies were used for fitting the potentials while others for examining their quality. The potentials correctly predict the equilibrium crystal structures of the phases and accurately reproduce their basic lattice properties. The potentials are applied to calculate the energies of point defects, surfaces, planar faults in the equilibrium structures. Unlike earlier EAM potentials for the Ti-Al system, the proposed potentials provide reasonable description of the lattice thermal expansion, demonstrating their usefulness in the molecular dynamics or Monte Carlo studies at high temperatures. The energy along the tetragonal deformation path (Bain transformation) in gamma-TiAl calculated with the EAM potential is in a fairly good agreement with LAPW calculations. Equilibrium point defect concentrations in gamma-TiAl are studied using the EAM potential. It is found that antisite defects strongly dominate over vacancies at all compositions around stoichiometry, indicating that gamm-TiAl is an antisite disorder compound in agreement with experimental data.Comment: 46 pages, 6 figures (Physical Review B, in press

    Micro-manufacturing : research, technology outcomes and development issues

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    Besides continuing effort in developing MEMS-based manufacturing techniques, latest effort in Micro-manufacturing is also in Non-MEMS-based manufacturing. Research and technological development (RTD) in this field is encouraged by the increased demand on micro-components as well as promised development in the scaling down of the traditional macro-manufacturing processes for micro-length-scale manufacturing. This paper highlights some EU funded research activities in micro/nano-manufacturing, and gives examples of the latest development in micro-manufacturing methods/techniques, process chains, hybrid-processes, manufacturing equipment and supporting technologies/device, etc., which is followed by a summary of the achievements of the EU MASMICRO project. Finally, concluding remarks are given, which raise several issues concerning further development in micro-manufacturing

    Advanced Methods for Dose and Regimen Finding During Drug Development: Summary of the EMA/EFPIA Workshop on Dose Finding (London 4-5 December 2014)

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    Inadequate dose selection for confirmatory trials is currently still one of the most challenging issues in drug development, as illustrated by high rates of late-stage attritions in clinical development and postmarketing commitments required by regulatory institutions. In an effort to shift the current paradigm in dose and regimen selection and highlight the availability and usefulness of well-established and regulatory-acceptable methods, the European Medicines Agency (EMA) in collaboration with the European Federation of Pharmaceutical Industries Association (EFPIA) hosted a multistakeholder workshop on dose finding (London 4-5 December 2014). Some methodologies that could constitute a toolkit for drug developers and regulators were presented. These methods are described in the present report: they include five advanced methods for data analysis (empirical regression models, pharmacometrics models, quantitative systems pharmacology models, MCP-Mod, and model averaging) and three methods for study design optimization (Fisher information matrix (FIM)-based methods, clinical trial simulations, and adaptive studies). Pairwise comparisons were also discussed during the workshop; however, mostly for historical reasons. This paper discusses the added value and limitations of these methods as well as challenges for their implementation. Some applications in different therapeutic areas are also summarized, in line with the discussions at the workshop. There was agreement at the workshop on the fact that selection of dose for phase III is an estimation problem and should not be addressed via hypothesis testing. Dose selection for phase III trials should be informed by well-designed dose-finding studies; however, the specific choice of method(s) will depend on several aspects and it is not possible to recommend a generalized decision tree. There are many valuable methods available, the methods are not mutually exclusive, and they should be used in conjunction to ensure a scientifically rigorous understanding of the dosing rationale
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