53,268 research outputs found
Material Dependence of the Wire-Particle Casimir Interaction
We study the Casimir interaction between a metallic cylindrical wire and a
metallic spherical particle by employing the scattering formalism. At large
separations, we derive the asymptotic form of the interaction. In addition, we
find the interaction between a metallic wire and an isotropic atom, both in the
non-retarded and retarded limits. We identify the conditions under which the
asymptotic Casimir interaction does not depend on the material properties of
the metallic wire and the particle. Moreover, we compute the exact Casimir
interaction between the particle and the wire numerically. We show that there
is a complete agreement between the numerics and the asymptotic energies at
large separations. For short separations, our numerical results show good
agreement with the proximity force approximation
Beam Dynamics Studies and Design Optimisation of New Low Energy Antiproton Facilities
Antiprotons, stored and cooled at low energies in a storage ring or at rest
in traps, are highly desirable for the investigation of a large number of basic
questions on fundamental interactions. This includes the static structure of
antiprotonic atomic systems and the time-dependent quantum dynamics of
correlated systems. The Antiproton Decelerator (AD) at CERN is currently the
worlds only low energy antiproton factory dedicated to antimatter experiments.
New antiproton facilities, such as the Extra Low ENergy Antiproton ring (ELENA)
at CERN and the Ultra-low energy Storage Ring (USR) at FLAIR, will open unique
possibilities. They will provide cooled, high quality beams of extra-low energy
antiprotons at intensities exceeding those achieved presently at the AD by
factors of ten to one hundred. These facilities, operating in the energy regime
between 100 keV down to 20 keV, face several design and beam dynamics
challenges, for example nonlinearities, space charge and scattering effects
limiting beam life time. Detailed investigations into the low energy and long
term beam dynamics have been carried out to address many of those challenges
towards the design optimisation. Results from these studies are presented in
this contribution, showing some examples for ELENA.Comment: 6 pages, 4 figures, 12th International Conference on Low Energy
Antiproton Physics, LEAP 2016. Submitted to JPS Conference Proceeding
Ultracold atoms at unitarity within quantum Monte Carlo
Variational and diffusion quantum Monte Carlo (VMC and DMC) calculations of
the properties of the zero-temperature fermionic gas at unitarity are reported.
The ratio of the energy of the interacting to the non-interacting gas for a
system of 128 particles is calculated to be 0.4517(3) in VMC and 0.4339(1) in
the more accurate DMC method. The spherically-averaged pair-correlation
functions, momentum densities, and one-body density matrices are very similar
in VMC and DMC, but the two-body density matrices and condensate fractions show
some differences. Our best estimate of the condensate fraction of 0.51 is a
little smaller than values from other quantum Monte Carlo calculations
The “New” Ticket to Work and Self-Sufficiency Program: Enhancing Economic Self-Sufficiency of Beneficiaries through Work Opportunities and Public/Private Partnership
Discusses the history of the Social Security Administration’s Vocational Rehabilitation and describes the intents and functioning of the Ticket to Work and work Incentives Improvement Act of 1999. This publication is based on federal Social Security and Supplemental Security Income (SSI) laws, regulations and policy. Following Sections I and II pertaining to historical context and evolution of SSA and the Ticket, information presented regarding the operations and structure of the Ticket to Work and Self-Sufficiency Program is based exclusively on the new 2008 regulations
Supporting Career Development and Employment: A Skill Development Practicum
This practicum workbook was designed to aid benefits planners and advocates in supporting the employment decision making process for individuals with disabilities. The first portion of the workbook discusses approaches for understanding interests, preferences, abilities and support needs; impact of choices on financial well-being and independence; supporting the service provider selection process; developing comprehensive work plans; and, quality assurance strategies to evaluate services and supports provided. The workbook concludes with a case application
Simulated evaluation of faceted browsing based on feature selection
In this paper we explore the limitations of facet based browsing which uses sub-needs of an information need for querying and organising the search process in video retrieval. The underlying assumption of this approach is that the search effectiveness will be enhanced if such an approach is employed for interactive video retrieval using textual and visual features. We explore the performance bounds of a faceted system by carrying out a simulated user evaluation on TRECVid data sets, and also on the logs of a prior user experiment with the system. We first present a methodology to reduce the dimensionality of features by selecting the most important ones. Then, we discuss the simulated evaluation strategies employed in our evaluation and the effect on the use of both textual and visual features. Facets created by users are simulated by clustering video shots using textual and visual features. The experimental results of our study demonstrate that the faceted browser can potentially improve the search effectiveness
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