47,920 research outputs found
Black holes and wormholes in AdS branes
In this work we have derived a class of geometries which describe black holes
and wormholes in Randall-Sundrum-type brane models, focusing mainly on
asymptotically anti-de Sitter backgrounds. We show that by continuously
deforming the usual four dimensional vacuum background, a specific family of
solutions is obtained. Maximal extensions of the solutions are presented, and
their causal structures are discussed.Comment: 7 pages, 4 figures. Published version in Physical Review
Group theoretic dimension of stationary symmetric \alpha-stable random fields
The growth rate of the partial maximum of a stationary stable process was
first studied in the works of Samorodnitsky (2004a,b), where it was
established, based on the seminal works of Rosi\'nski (1995,2000), that the
growth rate is connected to the ergodic theoretic properties of the flow that
generates the process. The results were generalized to the case of stable
random fields indexed by Z^d in Roy and Samorodnitsky (2008), where properties
of the group of nonsingular transformations generating the stable process were
studied as an attempt to understand the growth rate of the partial maximum
process. This work generalizes this connection between stable random fields and
group theory to the continuous parameter case, that is, to the fields indexed
by R^d.Comment: To appear in Journal of Theoretical Probability. Affiliation of the
authors are update
Secure, performance-oriented data management for nanoCMOS electronics
The EPSRC pilot project Meeting the Design Challenges of nanoCMOS Electronics (nanoCMOS) is focused upon delivering a production level e-Infrastructure to meet the challenges facing the semiconductor industry in dealing with the next generation of ‘atomic-scale’ transistor devices. This scale means that previous assumptions on the uniformity of transistor devices in electronics circuit and systems design are no longer valid, and the industry as a whole must deal with variability throughout the design process. Infrastructures to tackle this problem must provide seamless access to very large HPC resources for computationally expensive simulation of statistic ensembles of microscopically varying physical devices, and manage the many hundreds of thousands of files and meta-data associated with these simulations. A key challenge in undertaking this is in protecting the intellectual property associated with the data, simulations and design process as a whole. In this paper we present the nanoCMOS infrastructure and outline an evaluation undertaken on the Storage Resource Broker (SRB) and the Andrew File System (AFS) considering in particular the extent that they meet the performance and security requirements of the nanoCMOS domain. We also describe how metadata management is supported and linked to simulations and results in a scalable and secure manner
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The influence of physical and chemical linkage on the properties of nanocomposites
It has been shown by several groups that the mechanical and electrical behavior of composites changes quite substantially, and often beneficially, when the filler particle size is less than 100 nm in diameter. There is also good reason to believe that the interface between the embedded particulates and the polymer matrix holds the key to understanding the bulk phenomena observed. Materials based on an SiO2-polyolefin system have been formulated with functionalized particulates so as to affect the physical and chemical linkages. The agents used to achieve this include amino-silane, hexamethyl-disilazane and triethoxyvinylsilane. The emerging picture of the interface is supported by detailed dielectric spectroscopy and internal space charge assessment. The nature of the internal structure has been related to the bulk properties observed such as the breakdown strength, voltage endurance, and the measurement of internal charges resulting from interfacial polarization
Nonlinear photon transport in a semiconductor waveguide-cavity system containing a single quantum dot: Anharmonic cavity-QED regime
We present a semiconductor master equation technique to study the
input/output characteristics of coherent photon transport in a semiconductor
waveguide-cavity system containing a single quantum dot. We use this approach
to investigate the effects of photon propagation and anharmonic cavity-QED for
various dot-cavity interaction strengths, including weakly-coupled,
intermediately-coupled, and strongly-coupled regimes. We demonstrate that for
mean photon numbers much less than 0.1, the commonly adopted weak excitation
(single quantum) approximation breaks down, even in the weak coupling regime.
As a measure of the anharmonic multiphoton-correlations, we compute the Fano
factor and the correlation error associated with making a semiclassical
approximation. We also explore the role of electron--acoustic-phonon scattering
and find that phonon-mediated scattering plays a qualitatively important role
on the light propagation characteristics. As an application of the theory, we
simulate a conditional phase gate at a phonon bath temperature of K in the
strong coupling regime.Comment: To appear in PR
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