1,228 research outputs found
Localized mode interactions in 0-pi Josephson junctions
A long Josephson junction containing regions with a phase shift of pi is
considered. By exploiting the defect modes due to the discontinuities present
in the system, it is shown that Josephson junctions with phase-shift can be an
ideal setting for studying localized mode interactions. A phase-shift
configuration acting as a double-well potential is considered and shown to
admit mode tunnelings between the wells. When the phase-shift configuration is
periodic, it is shown that localized excitations forming bright and dark
solitons can be created. Multi-mode approximations are derived confirming the
numerical results.Comment: 4 pages, to appear in Phys. Rev.
Kinetic pathways of the Nematic-Isotropic phase transition as studied by confocal microscopy on rod-like viruses
We investigate the kinetics of phase separation for a mixture of rodlike
viruses (fd) and polymer (dextran), which effectively constitutes a system of
attractive rods. This dispersion is quenched from a flow-induced fully nematic
state into the region where the nematic and the isotropic phase coexist. We
show experimental evidence that the kinetic pathway depends on the overall
concentration. When the quench is made at high concentrations, the system is
meta-stable and we observe typical nucleation-and-growth. For quenches at low
concentration the system is unstable and the system undergoes a spinodal
decomposition. At intermediate concentrations we see the transition between
both demixing processes, where we locate the spinodal point.Comment: 11 pages, 6 figures, accepted in J. Phys.: Condens. Matter as
symposium paper for the 6th Liquid Matter Conference in Utrech
Incongruity, incongruity resolution, and mental states: The measure and modification of situational awareness and control
The research reported here describes the process of induction of various mental states. Our goals were to measure and to manipulate both the behavioral and the neurological correlates of particular mental states that have previously been demonstrated to be either beneficial or deleterious to in-flight performance situations. The experimental paradigm involved developing a context of which the participants were aware, followed by the introduction of an incongruity into that context. The empirical questions involved how the incongruity was resolved and the consequent effects on mental state. The dependent variables were measures of both the short-term ERP changes and the longer-term brain mapping indications of predominant mental states. The mission of NASA Flight Management Division and Human/Automation Integration Branch centers on the understanding and improvement of interaction between a complex system and a human operator. Specifically, the goal is improved efficiency through better operative procedures and control strategies. More efficient performance in demanding flight environments depends on improved situational awareness and replanning for fault management
Nematic-Isotropic Spinodal Decomposition Kinetics of Rod-like Viruses
We investigate spinodal decomposition kinetics of an initially nematic
dispersion of rod-like viruses (fd virus). Quench experiments are performed
from a flow-stabilized homogeneous nematic state at high shear rate into the
two-phase isotropic-nematic coexistence region at zero shear rate. We present
experimental evidence that spinodal decomposition is driven by orientational
diffusion, in accordance with a very recent theory.Comment: 17 pages, 6 figures, accepted in Phys. Rev.
Chloroplast ultrastructure of sugar beet (Beta vulgaris L.) cultivated in normal and elevated CO2 concentrations with two contrasted nitrogen supplies
Why Do Employers (Fail to) Hire People with Disabilities? : A Systematic Review of Capabilities, Opportunities and Motivations.
Purpose To increase the number of people with disabilities in employment, we need to understand what influences employers’ hiring decisions. In this systematic review, we map out factors affecting employers’ hiring decisions about people with disabilities. Methods This study is a systematic review that applies the COM-B model to identify factors that contribute to employers (not) hiring people with disabilities. The COM-B model proposes that employers will perform hiring behavior (B) if they have the capability (C), opportunity (O) and motivation (M) to do so. We also investigate if factors have a negative, positive or no effect. We report in accordance with the PRISMA guidelines. Results In a review of 47 studies, we find 32 factors. Most of these factors are barriers. The most frequently mentioned barriers are employers’ (1) expectations that people with disabilities are unproductive, (2) expectations that people with disabilities cost a lot of money, and employers’ (3) lack of knowledge about disabilities. The most researched facilitators for employers to hire people with disabilities include (1) the motivation to help others, (2) working in a large organization, and (3) expecting a competitive advantage. The effect of factors can differ depending on contextual circumstances, including the type of organization, the type of disability and different policies. Conclusions We conclude that hiring decisions are influenced by an array of different barriers and facilitators. The effect of these factors can differ across organizations and disability types. Our study of factors affecting hiring can be used by scholars, policy makers, and organizations to create interventions to increase the hiring of people with disabilities
Stability transitions for axisymmetric relative equilibria of Euclidean symmetric Hamiltonian systems
In the presence of noncompact symmetry, the stability of relative equilibria
under momentum-preserving perturbations does not generally imply robust
stability under momentum-changing perturbations. For axisymmetric relative
equilibria of Hamiltonian systems with Euclidean symmetry, we investigate
different mechanisms of stability: stability by energy-momentum confinement,
KAM, and Nekhoroshev stability, and we explain the transitions between these.
We apply our results to the Kirchhoff model for the motion of an axisymmetric
underwater vehicle, and we numerically study dissipation induced instability of
KAM stable relative equilibria for this system.Comment: Minor revisions. Typographical errors correcte
Cavitation-induced force transition in confined viscous liquids under traction
We perform traction experiments on simple liquids highly confined between
parallel plates. At small separation rates, we observe a simple response
corresponding to a convergent Poiseuille flow. Dramatic changes in the force
response occur at high separation rates, with the appearance of a force plateau
followed by an abrupt drop. By direct observation in the course of the
experiment, we show that cavitation accounts for these features which are
reminiscent of the utmost complex behavior of adhesive films under traction.
Surprisingly enough, this is observed here in purely viscous fluids.Comment: Submitted to Physical Review Letters on May 31, 2002. Related
informations on http://www.crpp.u-bordeaux.fr/tack.htm
A review of implant provision for hypodontia patients within a Scottish referral centre
Background: Implant treatment to replace congenitally missing teeth often involves multidisciplinary input in a secondary care environment. High quality patient care requires an in-depth knowledge of treatment requirements.
Aim: This service review aimed to determine treatment needs, efficiency of service and outcomes achieved in hypodontia patients. It also aimed to determine any specific difficulties encountered in service provision, and suggest methods to overcome these.
Methods: Hypodontia patients in the Unit of Periodontics of the Scottish referral centre under consideration, who had implant placement and fixed restoration, or review completed over a 31 month period, were included. A standardised data collection form was developed and completed with reference to the patient's clinical record. Information was collected with regard to: the indication for implant treatment and its extent; the need for, complexity and duration of orthodontic treatment; the need for bone grafting and the techniques employed and indicators of implant success.
Conclusion: Implant survival and success rates were high for those patients reviewed. Incidence of biological complications compared very favourably with the literature
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