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A Mass-Flux Scheme View of a High-Resolution Simulation of a Transition from Shallow to Deep Cumulus Convection
In this paper, an idealized, high-resolution simulation of a gradually forced transition from shallow, nonprecipitating to deep, precipitating cumulus convection is described; how the cloud and transport statistics evolve as the convection deepens is explored; and the collected statistics are used to evaluate assumptions in current cumulus schemes. The statistical analysis methodologies that are used do not require tracing the history of individual clouds or air parcels; instead they rely on probing the ensemble characteristics of cumulus convection in the large model dataset. They appear to be an attractive way for analyzing outputs from cloud-resolving numerical experiments. Throughout the simulation, it is found that 1) the initial thermodynamic properties of the updrafts at the cloud base have rather tight distributions; 2) contrary to the assumption made in many cumulus schemes, nearly undiluted air parcels are too infrequent to be relevant to any stage of the simulated convection; and 3) a simple model with a spectrum of entraining plumes appears to reproduce most features of the cloudy updrafts, but significantly overpredicts the mass flux as the updrafts approach their levels of zero buoyancy. A buoyancy-sorting model was suggested as a potential remedy. The organized circulations of cold pools seem to create clouds with larger-sized bases and may correspondingly contribute to their smaller lateral entrainment rates. Our results do not support a mass-flux closure based solely on convective available potential energy (CAPE), and are in general agreement with a convective inhibition (CIN)-based closure. The general similarity in the ensemble characteristics of shallow and deep convection and the continuous evolution of the thermodynamic structure during the transition provide justification for developing a single unified cumulus parameterization that encompasses both shallow and deep convection
S-D mixing and production in annihilation and B decay and its radiative transitions
The large decay rate observed by Belle for , which is
comparable to , might indicate either an unexpectedly
large S-D mixing angle or the leading role of the
color-octet mechanism in D-wave charmonium production in B decay. By
calculating the production rate of in the continuum
annihilation at GeV with these two possible approaches (i.e.
the large S-D mixing and the color-octet mechanism), we show that the
measurement for this process at Belle and BaBar may provide a clear cut
clarification for the two approaches. In addition, the radiative E1 transition
ratio may dramatically change from 0.04 (for ) to 200 (for ) due to the large S-D
interference effect, thus the E1 transition measurement of at BES
and CLEO-c will also be very useful in clarifying this issue.Comment: final version to appear in Phys.Rev.D, discussion on uncertainties
associated with the color-octet matrix elements is added, 16 pages, 2 figure
Quantum discord amplification induced by quantum phase transition via a cavity-Bose-Einstein-condensate system
We propose a theoretical scheme to realize a sensitive amplification of
quantum discord (QD) between two atomic qubits via a cavity-Bose-Einstein
condensate (BEC) system which was used to firstly realize the Dicke quantum
phase transition (QPT) [Nature 464, 1301 (2010)]. It is shown that the
influence of the cavity-BEC system upon the two qubits is equivalent to a phase
decoherence environment. It is found that QPT in the cavity-BEC system is the
physical mechanism of the sensitive QD amplification.Comment: 5 pages, 3 figure
Soliton transverse instabilities in nonlocal nonlinear media
We analyze the transverse instabilities of spatial bright solitons in
nonlocal nonlinear media, both analytically and numerically. We demonstrate
that the nonlocal nonlinear response leads to a dramatic suppression of the
transverse instability of the soliton stripes, and we derive the asymptotic
expressions for the instability growth rate in both short- and long-wave
approximations.Comment: 3 pages, 3 figure
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