3,073 research outputs found
Non-Leptonic B Decays into K-Resonances
We estimate the non-leptonic B decays , where 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 results in higher resonances
of K-meson and besides , a considerable fraction of
goes to .Comment: 9 pages, late
CLEO-c hot topics
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 Ï(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
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
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
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
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
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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