3,073 research outputs found

    Non-Leptonic B Decays into K-Resonances

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    We estimate the non-leptonic B decays B→(ψ,ψâ€Č,χ1c)+KiB \rightarrow (\psi ,\psi^\prime , \chi_{1c})+K^i, where KiK^i are various K-meson resonances. We use the model of Isgur, Wise, Scora and Grinstein in the context of heavy quark effective theory, to calculate the hadronic matrix elements. Our estimates show that a substantial fraction of B→XsψB \rightarrow X_s \psi results in higher resonances of K-meson and besides B→K(K∗)ψB \rightarrow K(K^*) \psi, a considerable fraction of B→Xs(ccˉ)B \rightarrow X_s (c\bar c) goes to B→(K,K∗)+(ψâ€Č,χ1c)B \rightarrow (K,K^*)+( \psi^{\prime},\chi_{1c}).Comment: 9 pages, late

    CLEO-c hot topics

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    Selected recent results and future prospects for the CLEO-c experiment at CESR are reviewed. The topics covered include measurements of leptonic and semileptonic charm decays made with data collected at the ψ(3770) resonance and results from a scan of the center-of-mass energy range from 3970 to 4260 MeV addressing the details of open-charm production and properties of the Y (4260) state observed last year by BaBar

    Reliability Testing of AlGaN/GaN HEMTs Under Multiple Stressors

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    We performed an experiment on AlGaN/GaN HEMTs with high voltage and high power as stressors. We found that devices tested under high power generally degraded more than those tested under high voltage. In particular, the high-voltage-tested devices did not degrade significantly as suggested by some papers in the literature. The same papers in the literature also suggest that high voltages cause cracks and pits. However, the high-voltage-tested devices in this study do not exhibit cracks or pits in TEM images, while the high-power-tested devices exhibit pits

    Analytical approximation for the sphere-sphere Coulomb potential

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    A simple analytical expression, which closely approximates the Coulomb potential between two uniformly charged spheres, is presented. This expression can be used in the optical potential semiclassical analyses which require that the interaction be analytic on and near the real r-axis.Comment: 4 pages including 3 figures and 1 tabl

    Numerical framework for transcritical real-fluid reacting flow simulations using the flamelet progress variable approach

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    An extension to the classical FPV model is developed for transcritical real-fluid combustion simulations in the context of finite volume, fully compressible, explicit solvers. A double-flux model is developed for transcritical flows to eliminate the spurious pressure oscillations. A hybrid scheme with entropy-stable flux correction is formulated to robustly represent large density ratios. The thermodynamics for ideal-gas values is modeled by a linearized specific heat ratio model. Parameters needed for the cubic EoS are pre-tabulated for the evaluation of departure functions and a quadratic expression is used to recover the attraction parameter. The novelty of the proposed approach lies in the ability to account for pressure and temperature variations from the baseline table. Cryogenic LOX/GH2 mixing and reacting cases are performed to demonstrate the capability of the proposed approach in multidimensional simulations. The proposed combustion model and numerical schemes are directly applicable for LES simulations of real applications under transcritical conditions.Comment: 55th AIAA Aerospace Sciences Meeting, Dallas, T

    Real-Gas Effects and Phase Separation in Underexpanded Jets at Engine-Relevant Conditions

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    A numerical framework implemented in the open-source tool OpenFOAM is presented in this work combining a hybrid, pressure-based solver with a vapor-liquid equilibrium model based on the cubic equation of state. This framework is used in the present work to investigate underexpanded jets at engine-relevant conditions where real-gas effects and mixture induced phase separation are probable to occur. A thorough validation and discussion of the applied vapor-liquid equilibrium model is conducted by means of general thermodynamic relations and measurement data available in the literature. Engine-relevant simulation cases for two different fuels were defined. Analyses of the flow field show that the used fuel has a first order effect on the occurrence of phase separation. In the case of phase separation two different effects could be revealed causing the single-phase instability, namely the strong expansion and the mixing of the fuel with the chamber gas. A comparison of single-phase and two-phase jets disclosed that the phase separation leads to a completely different penetration depth in contrast to single-phase injection and therefore commonly used analytical approaches fail to predict the penetration depth.Comment: Preprint submitted to AIAA Scitech 2018, Kissimmee, Florid

    Advancing Clinical Practice through Integration of Congenital Cytomegalovirus (cCMV) Testing with Newborn Hearing Screening at Mayo Clinic

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    Although cCMV is the leading non-genetic cause of childhood hearing loss in the United States, neither targeted nor universal screening protocols have been well established to identify cCMV in newborns. Moreover, until cCMV testing is universal, clinical protocols need to account for the complexities of individualized care in partnership with interprofessional care teams. This work addressed an immediate clinical practice need to identify cCMV with subsequent hearing monitoring of babies who test positive for cCMV. This effort focused on three primary objectives to: 1) define interprofessional, team-based approach to facilitate care pathways; 2) develop a clinical workflow for all babies who refer on inpatient hearing screening to be tested for cCMV by 21 days of age; 3) develop a hearing monitoring plan for all babies who test positive for cCMV. The development and integration of our interprofessional, team-based approach to institute cCMV testing by 21 days of age on all babies who refer inpatient newborn hearing screening and subsequent monitoring is described. Our observed referral rate was lower than predicted (2.7%) from existing literature with only one positive cCMV outcome noted in the two-year span. This study demonstrates the feasibility of a hearing-targeted cCMV testing paradigm in our clinic practice
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