5,174 research outputs found
Strong converse rates for classical communication over thermal and additive noise bosonic channels
We prove that several known upper bounds on the classical capacity of thermal
and additive noise bosonic channels are actually strong converse rates. Our
results strengthen the interpretation of these upper bounds, in the sense that
we now know that the probability of correctly decoding a classical message
rapidly converges to zero in the limit of many channel uses if the
communication rate exceeds these upper bounds. In order for these theorems to
hold, we need to impose a maximum photon number constraint on the states input
to the channel (the strong converse property need not hold if there is only a
mean photon number constraint). Our first theorem demonstrates that Koenig and
Smith's upper bound on the classical capacity of the thermal bosonic channel is
a strong converse rate, and we prove this result by utilizing the structural
decomposition of a thermal channel into a pure-loss channel followed by an
amplifier channel. Our second theorem demonstrates that Giovannetti et al.'s
upper bound on the classical capacity of a thermal bosonic channel corresponds
to a strong converse rate, and we prove this result by relating success
probability to rate, the effective dimension of the output space, and the
purity of the channel as measured by the Renyi collision entropy. Finally, we
use similar techniques to prove that similar previously known upper bounds on
the classical capacity of an additive noise bosonic channel correspond to
strong converse rates.Comment: Accepted for publication in Physical Review A; minor changes in the
text and few reference
Discontinuity in the Environment, Firm Response and Dynamic Capabilities
This paper identifies and focuses on a specific type of environmental development called discontinuity. Discontinuities in the forms of rapid technological innovations, regulatory reforms, institutional overhauls, and socio-cultural developments are the source of opportunities and threats to the firm. Firm responds to these discontinuities in specific ways in sustaining its existence at different points of time. This paper conceptualizes discontinuity and identifies its natures; explores the possible types of responses by the firm, and their enablers. The capability of sensing, seizing and re-shaping are captured to establish the linkages in the framework of interrelations. It posits a set of propositions based on conceptual development and illustration of two cases.
Modification of the Unitarity Relation for sin2beta-Vub in Supersymmetric Models
Recently, a more than 2sigma discrepancy has been observed between the well
measured inclusive value of Vub and the predicted value of Vub from the
unitarity triangle fit using the world average value of sin2beta. We attempt to
resolve this tension in the context of grand unified SO(10) and SU(5) models
where the neutrino mixing matrix is responsible for flavor changing neutral
current at the weak scale and the models with non-proportional A-terms (can be
realized simply in the context of intersecting D-brane models) and investigate
the interplay between the constraints arising from B_{s,d}-\bar B_{s,d}
mixings, epsilon_K, Br(tau -> mu gamma), Br(mu -> e gamma) and a fit of this
new discrepancy. We also show that the ongoing measurement of the phase of Bs
mixing will be able to identify the grand unified model. The measurement of
Br(tau -> e gamma) will also be able to test these scenarios, especially the
models with non-proportional A-terms.Comment: 20 pages, 4 figures. Minor corrections, references adde
Weld sequence optimization: the use of surrogate models for solving sequential combinatorial problems
The solution of combinatorial optimization problems usually involves the consideration of many possible design configurations. This often makes such approaches computationally expensive, especially when dealing with complex finite element models. Here a surrogate model is proposed that can be used to reduce substantially the computational expense of sequential combinatorial finite element problems. The model is illustrated by application to a weld path planning problem
EFFICIENCY ANALYSIS OF HOSPITALS IN THE GREAT PLAINS: AN URBAN-RURAL COMPARISON
This study examined the efficiency of a sample of hospitals in the Great Plains using a nonparametric approach. Technical efficiency was less than either allocative or scale efficiency. Urban hospitals are relatively more efficient than rural hospitals with respect to all efficiency measures. Private hospitals are more efficient than others.Health Economics and Policy,
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