1,340 research outputs found

    Factorization, charming penguins, and all that

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    We discuss few selected topics related to the calculation of hadronic amplitudes relevant for two-body non-leptonic B decays.Comment: LaTeX, 9 pages, 1 eps figure included, uses psfig.sty. Talk given by M.C. at Beauty '97, UCLA, USA, October 13-17, 199

    Direct CP Violation in B->phi K_s and New Physics

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    In the presence of large New Physics contributions to loop-induced b->s transitions, sizable direct CP violation in B-> phi K decays is expected on general grounds. We compute explicitly CP-violating effects using QCD factorization and find that, even in the restricted case in which New Physics has the same penguin structure as the Standard Model, the rate asymmetry can be of order one. We briefly discuss a more general scenario and comment on the inclusion of power-suppressed corrections to factorization.Comment: 3 page

    Design of experiments for non-manufacturing processes : benefits, challenges and some examples

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    Design of Experiments (DoE) is a powerful technique for process optimization that has been widely deployed in almost all types of manufacturing processes and is used extensively in product and process design and development. There have not been as many efforts to apply powerful quality improvement techniques such as DoE to improve non-manufacturing processes. Factor levels often involve changing the way people work and so have to be handled carefully. It is even more important to get everyone working as a team. This paper explores the benefits and challenges in the application of DoE in non-manufacturing contexts. The viewpoints regarding the benefits and challenges of DoE in the non-manufacturing arena are gathered from a number of leading academics and practitioners in the field. The paper also makes an attempt to demystify the fact that DoE is not just applicable to manufacturing industries; rather it is equally applicable to non-manufacturing processes within manufacturing companies. The last part of the paper illustrates some case examples showing the power of the technique in non-manufacturing environments

    Inhomogeneous Superconductivity in Comb-Shaped Josephson Junction Networks

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    We show that some of the Josephson couplings of junctions arranged to form an inhomogeneous network undergo a non-perturbative renormalization provided that the network's connectivity is pertinently chosen. As a result, the zero-voltage Josephson critical currents IcI_c turn out to be enhanced along directions selected by the network's topology. This renormalization effect is possible only on graphs whose adjacency matrix admits an hidden spectrum (i.e. a set of localized states disappearing in the thermodynamic limit). We provide a theoretical and experimental study of this effect by comparing the superconducting behavior of a comb-shaped Josephson junction network and a linear chain made with the same junctions: we show that the Josephson critical currents of the junctions located on the comb's backbone are bigger than the ones of the junctions located on the chain. Our theoretical analysis, based on a discrete version of the Bogoliubov-de Gennes equation, leads to results which are in good quantitative agreement with experimental results.Comment: 4 pages, 2 figures, revte

    High-fidelity simulations of gravity currents using a high-order finite-difference spectral vanishing viscosity approach

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    This numerical work investigates the potential of a high-order finite-difference spectral vanishing viscosity approach to simulate gravity currents at high Reynolds numbers. The method introduces targeted numerical dissipation at small scales through altering the discretisation of the second derivatives of the viscous terms in the incompressible Navier-Stokes equations to mimic the spectral vanishing viscosity (SVV) operator, originally designed for the regularisation of spectral element method (SEM) solutions of pure advection problems. Using a sixth-order accurate finite-difference scheme, the adoption of the SVV method is straightforward and comes with a negligible additional computational cost. In order to assess the ability of this high-order finite-difference spectral vanishing viscosity approach, we performed large-eddy simulations (LES) of a gravity current in a channelised lock-exchange set-up with our SVV model and with the well-known explicit static and dynamic Smagorinsky sub-grid scale (SGS) models. The obtained data are compared with a direct numerical simulation (DNS) based on more than 800 million mesh nodes, and with experimental measurements. A framework for the energy budget is introduced to investigate the behaviour of the gravity current. First, it is found that the DNS is in good agreement with the experimental data for the evolution of the front location and velocity field as well as for the stirring and mixing inside the gravity current. Secondly, the LES performed with less than 0.4% of the total number of mesh nodes compared to the DNS, can reproduce the main features of the gravity currents, with the SVV model yielding slightly more accurate results. It is also found that the dynamic Smagorinsky model performs better than its static version. For the present study, the static and dynamic Smagorinsky models are 1.8 and 2.5 times more expensive than the SVV model, because the latter does not require the calculation of explicit SGS terms in the Navier-Stokes equations nor spatial filtering operations

    Contribution of 3H-thymidine labelling index and flow cytometric S-phase in predicting survival of patients with non-Hodgkin's lymphoma.

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    The 3H-thymidine labelling index (3H-dT LI) of cell suspensions from fresh material and the flow cytometric S-phase (FCM-S) of nuclei recovered from paraffin blocks were determined on the same pathologic lymph node specimen for 190 non-Hodgkin's lymphomas (NHLs). FCM-S was defined by a planimetric method and by an optimization procedure. Poor correlation coefficients were observed among the three cell kinetic variables. All three cell kinetic variables were significant indicators of 8-year survival and median survival time. The life-regression procedure evidenced a significant relative contribution of 3H-dT LI and FCM-S, thus suggesting a different biologic meaning of the two cell kinetic variables. This finding was further supported by evidence that simultaneous use of 3H-dT LI and FCM-S can identify groups of patients with different survival better than when either modality is used alone. Multivariate analysis indicated that the risk groups as defined by cell kinetic variables are predictors of survival even in the presence of established factors such as histology and stage
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