138 research outputs found
Policy, Principle, or Values: An Exploration of Judicial Decision-Making
The article reveals the values underpinning judicial decisions in three cases in which the complexity and legal uncertainty divided the court and argues that the language of public policy is used to frame a decision based on judicial values
Resonant thermal transport in semiconductor barrier structures
I report that thermal single-barrier (TSB) and thermal double-barrier (TDB)
structures (formed, for example, by inserting one or two regions of a few Ge
monolayers in Si) provide both a suppression of the phonon transport as well as
a resonant-thermal-transport effect. I show that high-frequency phonons can
experience a traditional double-barrier resonant tunneling in the TDB
structures while the formation of Fabry-Perot resonances (at lower frequencies)
causes quantum oscillations in the temperature variation of both the TSB and
TDB thermal conductances and .Comment: 4 pages. 4 figure.
Relative sea-level change in Newfoundland, Canada during the past ∼3000 years
Several processes contributing to coastal relative sea-level (RSL) change in the North Atlantic Ocean are observed and/or predicted to have distinctive spatial expressions that vary by latitude. To expand the latitudinal range of RSL records spanning the past ∼3000 years and the likelihood of recognizing the characteristic fingerprints of these processes, we reconstructed RSL at two sites (Big River and Placentia) in Newfoundland from salt-marsh sediment. Bayesian transfer functions established the height of former sea level from preserved assemblages of foraminifera and testate amoebae. Age-depth models constrained by radiocarbon dates and chronohorizons estimated the timing of sediment deposition. During the past ∼3000 years, RSL rose by ∼3.0 m at Big River and by ∼1.5 m at Placentia. A locally calibrated geotechnical model showed that post-depositional lowering through sediment compaction was minimal. To isolate and quantify contributions to RSL from global, regional linear, regional non-linear, and local-scale processes, we decomposed the new reconstructions (and those in an expanded, global database) using a spatio-temporal statistical model. The global component confirms that 20th century sea-level rise occurred at the fastest, century-scale rate in over 3000 years (P > 0.999). Distinguishing the contributions from local and regional non-linear processes is made challenging by a sparse network of reconstructions. However, only a small contribution from local-scale processes is necessary to reconcile RSL reconstructions and modeled RSL trends. We identified three latitudinally-organized groups of sites that share coherent regional non-linear trends and indicate that dynamic redistribution of ocean mass by currents and/or winds was likely an important driver of sea-level change in the North Atlantic Ocean during the past ∼3000 years
Looking into the matter of light-quark hadrons
In tackling QCD, a constructive feedback between theory and extant and
forthcoming experiments is necessary in order to place constraints on the
infrared behaviour of QCD's \beta-function, a key nonperturbative quantity in
hadron physics. The Dyson-Schwinger equations provide a tool with which to work
toward this goal. They connect confinement with dynamical chiral symmetry
breaking, both with the observable properties of hadrons, and hence provide a
means of elucidating the material content of real-world QCD. This contribution
illustrates these points via comments on: in-hadron condensates; dressed-quark
anomalous chromo- and electro-magnetic moments; the spectra of mesons and
baryons, and the critical role played by hadron-hadron interactions in
producing these spectra.Comment: 11 pages, 7 figures. Contribution to the Proceedings of "Applications
of light-cone coordinates to highly relativistic systems - LIGHTCONE 2011,"
23-27 May, 2011, Dallas. The Proceedings will be published in Few Body
System
Masses of ground and excited-state hadrons
We present the first Dyson-Schwinger equation calculation of the light hadron
spectrum that simultaneously correlates the masses of meson and baryon ground-
and excited-states within a single framework. At the core of our analysis is a
symmetry-preserving treatment of a vector-vector contact interaction. In
comparison with relevant quantities the
root-mean-square-relative-error/degree-of freedom is 13%. Notable amongst our
results is agreement between the computed baryon masses and the bare masses
employed in modern dynamical coupled-channels models of pion-nucleon reactions.
Our analysis provides insight into numerous aspects of baryon structure; e.g.,
relationships between the nucleon and Delta masses and those of the
dressed-quark and diquark correlations they contain.Comment: 25 pages, 7 figures, 4 table
State sampling dependence of the Hopfield network inference
The fully connected Hopfield network is inferred based on observed
magnetizations and pairwise correlations. We present the system in the glassy
phase with low temperature and high memory load. We find that the inference
error is very sensitive to the form of state sampling. When a single state is
sampled to compute magnetizations and correlations, the inference error is
almost indistinguishable irrespective of the sampled state. However, the error
can be greatly reduced if the data is collected with state transitions. Our
result holds for different disorder samples and accounts for the previously
observed large fluctuations of inference error at low temperatures.Comment: 4 pages, 1 figure, further discussions added and relevant references
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Quantum optics in the phase space - A tutorial on Gaussian states
In this tutorial, we introduce the basic concepts and mathematical tools
needed for phase-space description of a very common class of states, whose
phase properties are described by Gaussian Wigner functions: the Gaussian
states. In particular, we address their manipulation, evolution and
characterization in view of their application to quantum information.Comment: Tutorial. 23 pages, 1 figure. Updated version accepted for
publication in EPJ - ST devoted to the memory of Federico Casagrand
Generation of entangled coherent states via cross phase modulation in a double electromagnetically induced transparency regime
The generation of an entangled coherent state is one of the most important
ingredients of quantum information processing using coherent states. Recently,
numerous schemes to achieve this task have been proposed. In order to generate
travelling-wave entangled coherent states, cross phase modulation, optimized by
optical Kerr effect enhancement in a dense medium in an electromagnetically
induced transparency (EIT) regime, seems to be very promising. In this
scenario, we propose a fully quantized model of a double-EIT scheme recently
proposed [D. Petrosyan and G. Kurizki, {\sl Phys. Rev. A} {\bf 65}, 33833
(2002)]: the quantization step is performed adopting a fully Hamiltonian
approach. This allows us to write effective equations of motion for two
interacting quantum fields of light that show how the dynamics of one field
depends on the photon-number operator of the other. The preparation of a
Schr\"odinger cat state, which is a superposition of two distinct coherent
states, is briefly exposed. This is based on non-linear interaction via
double-EIT of two light fields (initially prepared in coherent states) and on a
detection step performed using a beam splitter and two photodetectors.
In order to show the entanglement of a generated entangled coherent state, we
suggest to measure the joint quadrature variance of the field. We show that the
entangled coherent states satisfy the sufficient condition for entanglement
based on quadrature variance measurement. We also show how robust our scheme is
against a low detection efficiency of homodyne detectors.Comment: 15 pages, 9 figures; extensively revised version; added Section
The Similarity Hypothesis in General Relativity
Self-similar models are important in general relativity and other fundamental
theories. In this paper we shall discuss the ``similarity hypothesis'', which
asserts that under a variety of physical circumstances solutions of these
theories will naturally evolve to a self-similar form. We will find there is
good evidence for this in the context of both spatially homogenous and
inhomogeneous cosmological models, although in some cases the self-similar
model is only an intermediate attractor. There are also a wide variety of
situations, including critical pheneomena, in which spherically symmetric
models tend towards self-similarity. However, this does not happen in all cases
and it is it is important to understand the prerequisites for the conjecture.Comment: to be submitted to Gen. Rel. Gra
Collective perspective on advances in Dyson-Schwinger Equation QCD
We survey contemporary studies of hadrons and strongly interacting quarks
using QCD's Dyson-Schwinger equations, addressing: aspects of confinement and
dynamical chiral symmetry breaking; the hadron spectrum; hadron elastic and
transition form factors, from small- to large-Q^2; parton distribution
functions; the physics of hadrons containing one or more heavy quarks; and
properties of the quark gluon plasma.Comment: 56 pages. Summary of lectures delivered by the authors at the
"Workshop on AdS/CFT and Novel Approaches to Hadron and Heavy Ion Physics,"
2010-10-11 to 2010-12-03, hosted by the Kavli Institute for Theoretical
Physics, China, at the Chinese Academy of Science
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