2,892 research outputs found
Dynamics of localization in a waveguide
This is a review of the dynamics of wave propagation through a disordered
N-mode waveguide in the localized regime. The basic quantities considered are
the Wigner-Smith and single-mode delay times, plus the time-dependent power
spectrum of a reflected pulse. The long-time dynamics is dominated by resonant
transmission over length scales much larger than the localization length. The
corresponding distribution of the Wigner-Smith delay times is the Laguerre
ensemble of random-matrix theory. In the power spectrum the resonances show up
as a 1/t^2 tail after N^2 scattering times. In the distribution of single-mode
delay times the resonances introduce a dynamic coherent backscattering effect,
that provides a way to distinguish localization from absorption.Comment: 18 pages including 8 figures; minor correction
Critical Assessment of Outcomes in Acute Aortic Dissection (Type A) at a Community Hospital: A 10 year review
Nonlinear Sigma Model for Disordered Media: Replica Trick for Non-Perturbative Results and Interactions
In these lectures, given at the NATO ASI at Windsor (2001), applications of
the replicas nonlinear sigma model to disordered systems are reviewed. A
particular attention is given to two sets of issues. First, obtaining
non-perturbative results in the replica limit is discussed, using as examples
(i) an oscillatory behaviour of the two-level correlation function and (ii)
long-tail asymptotes of different mesoscopic distributions. Second, a new
variant of the sigma model for interacting electrons in disordered normal and
superconducting systems is presented, with demonstrating how to reduce it,
under certain controlled approximations, to known ``phase-only'' actions,
including that of the ``dirty bosons'' model.Comment: 25 pages, Proceedings of the NATO ASI "Field Theory of Strongly
Correlated Fermions and Bosons in Low - Dimensional Disordered Systems",
Windsor, August, 2001; to be published by Kluwe
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Harnessing the Creative Potential of Consumers: Money, Participation and Creativity in Idea Crowdsourcing
Given the growing importance of innovation and consumer engagement, many firms are strongly interested in finding ways to encourage their consumers to generate creative new product ideas for them in their crowdsourcing initiatives. To that end, managers often use monetary rewards – one of the most commonly used managerial tools to stimulate desired behaviors. A critical question in this respect is whether the use of monetary rewards is effective in stimulating creativity and, if so, how large those rewards should be. This study aims to answer these questions. The results of an experiment suggest that introducing monetary rewards does not contribute to the number of new product ideas generated by a single consumer or the novelty of his/her ideas, and when the reward is relatively small it can even be harmful. Monetary rewards, however, are effective in encouraging widespread participation in crowdsourcing initiatives and improving the appropriateness of the new product ideas. As a whole, these findings take us a step further toward better understanding the motivational mechanisms of consumer creativity in new product ideation
A randomized double-blind trial of an interventional device treatment of functional mitral regurgitation in patients with symptomatic congestive heart failure-Trial design of the REDUCE FMR study
The Carillon Mitral Contour System has been studied in 3 nonrandomized trials in patients with symptomatic congestive heart failure and functional mitral regurgitation. The REDUCE FMR study is a uniquely designed, double-blind trial evaluating the impact of the Carillon device on reducing regurgitant volume, as well as assessing the safety and clinical efficacy of this device. Carillon is a coronary sinus-based indirect annuloplasty device. Eligible patients undergo an invasive venogram to assess coronary sinus vein suitability for the Carillon device. If the venous dimensions are suitable, they are randomized on a 3:1 basis to receive a device or not. Patients and assessors are blinded to the treatment assignment. The primary end point is the difference in regurgitant volume at 1 year between the implanted and nonimplanted groups. Other comparisons include clinical parameters such as heart failure hospitalizations, 6-minute walk test, Kansas City Cardiomyopathy Questionnaire (KCCQ), and other echocardiographic parameters. An exercise echo substudy will also be included
Imaging in population science: cardiovascular magnetic resonance in 100,000 participants of UK Biobank - rationale, challenges and approaches
PMCID: PMC3668194SEP was directly funded by the National Institute for Health Research
Cardiovascular Biomedical Research Unit at Barts. SN acknowledges support
from the Oxford NIHR Biomedical Research Centre and from the Oxford
British Heart Foundation Centre of Research Excellence. SP and PL are
funded by a BHF Senior Clinical Research fellowship. RC is supported by a
BHF Research Chair and acknowledges the support of the Oxford BHF Centre
for Research Excellence and the MRC and Wellcome Trust. PMM gratefully
acknowledges training fellowships supporting his laboratory from the
Wellcome Trust, GlaxoSmithKline and the Medical Research Council
Haloperidol differentially modulates prepulse inhibition and p50 suppression in healthy humans stratified for low and high gating levels
Schizophrenia patients exhibit deficits in sensory gating as indexed by reduced prepulse inhibition (PPI) and P50 suppression, which have been linked to psychotic symptom formation and cognitive deficits. Although recent evidence suggests that atypical antipsychotics might be superior over typical antipsychotics in reversing PPI and P50 suppression deficits not only in schizophrenia patients, but also in healthy volunteers exhibiting low levels of PPI, the impact of typical antipsychotics on these gating measures is less clear. To explore the impact of the dopamine D2-like receptor system on gating and cognition, the acute effects of haloperidol on PPI, P50 suppression, and cognition were assessed in 26 healthy male volunteers split into subgroups having low vs high PPI or P50 suppression levels using a placebo-controlled within-subject design. Haloperidol failed to increase PPI in subjects exhibiting low levels of PPI, but attenuated PPI in those subjects with high sensorimotor gating levels. Furthermore, haloperidol increased P50 suppression in subjects exhibiting low P50 gating and disrupted P50 suppression in individuals expressing high P50 gating levels. Independently of drug condition, high PPI levels were associated with superior strategy formation and execution times in a subset of cognitive tests. Moreover, haloperidol impaired spatial working memory performance and planning ability. These findings suggest that dopamine D2-like receptors are critically involved in the modulation of P50 suppression in healthy volunteers, and to a lesser extent also in PPI among subjects expressing high sensorimotor gating levels. Furthermore, the results suggest a relation between sensorimotor gating and working memory performance
Antimicrobial resistance profiles of Shiga toxin-producing Escherichia coli O157 and Non-O157 recovered from domestic farm animals in rural communities in Northwestern Mexico
Characterization of complex networks: A survey of measurements
Each complex network (or class of networks) presents specific topological
features which characterize its connectivity and highly influence the dynamics
of processes executed on the network. The analysis, discrimination, and
synthesis of complex networks therefore rely on the use of measurements capable
of expressing the most relevant topological features. This article presents a
survey of such measurements. It includes general considerations about complex
network characterization, a brief review of the principal models, and the
presentation of the main existing measurements. Important related issues
covered in this work comprise the representation of the evolution of complex
networks in terms of trajectories in several measurement spaces, the analysis
of the correlations between some of the most traditional measurements,
perturbation analysis, as well as the use of multivariate statistics for
feature selection and network classification. Depending on the network and the
analysis task one has in mind, a specific set of features may be chosen. It is
hoped that the present survey will help the proper application and
interpretation of measurements.Comment: A working manuscript with 78 pages, 32 figures. Suggestions of
measurements for inclusion are welcomed by the author
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