7,786 research outputs found
Effective potential for nonrelativistic non-Abelian Chern-Simons matter system in constant background fields
We present the effective potential for nonrelativistic matter coupled to
non-Abelian Chern-Simons gauge fields. We perform the calculation using a
functional method in constant background fields to satisfy Gauss's law and to
simplify the computation. Both the quantum gauge and matter fields are
integrated over. The gauge fixing is achieved with an -gauge in the
limit. Divergences appearing in the matter sector are regulated via
operator regularization. We find no corrections to the Chern-Simons coupling
constant and the system experiences conformal symmetry breaking to one-loop
order except at the known value of self-duality. These results agree with
previous analysis of the non-Abelian Aharonov-Bohm scattering.Comment: 17 pages in Tex (phyzzx), UdeM-LPN-TH-94-200, CRM-219
Micromagnetic simulations of sweep-rate dependent coercivity in perpendicular recording media
The results of micromagnetic simulations are presented which examine the
impact of thermal fluctuations on sweep rate dependent coercivities of both
single-layer and exchange-coupled-composite (ECC) perpendicular magnetic
recording media. M-H loops are calculated at four temperatures and sweep rates
spanning five decades with fields applied normal to the plane and at 45
degrees. The impact of interactions between grains is evaluated. The results
indicate a significantly weaker sweep-rate dependence for ECC media suggesting
more robustness to long-term thermal effects. Fitting the modeled results to
Sharrock-like scaling proposed by Feng and Visscher [J. Appl. Phys. 95, 7043
(2004)] is successful only in the case of single-layer media with the field
normal to the plane.Comment: 7 pages, 14 figure
Design, development and evaluation of Stanford/Ames Extra-Vehicular Activity (EVA) prehensors
A summary is given of progress to date on work proposed in 1983 and continued in 1985, including design iterations on three different types of manually powered prehensors, construction of functional mockups of each and culminating in detailed drawings and specifications for suit-compatible sealed units for testing under realistic conditions
Design, development and evaluation of Stanford/Ames EVA prehensors
Space Station operations and maintenance are expected to make unprecedented demands on astronaut EVA. With Space Station expected to operate with an 8 to 10 psi atmosphere (4 psi for Shuttle operations), the effectivness of pressurized gloves is called into doubt at the same time that EVA activity levels are to be increased. To address the need for more frequent and complex EVA missions and also to extend the dexterity, duration, and safety of EVA astronauts, NASA Ames and Stanford University have an ongoing cooperative agreement to explore and compare alternatives. This is the final Stanford/Ames report on manually powered Prehensors, each of which consists of a shroud forming a pressure enclosure around the astronaut's hand, and a linkage system to transfer the motions and forces of the hand to mechanical digits attached to the shroud. All prehensors are intended for attachment to a standard wrist coupling, as found on the AX-5 hard suit prototype, so that realistic tests can be performed under normal and reduced gravity as simulated by water flotation
Effect of Desiccation, pH, Heat, and Ultraviolet Irradiation on Viability of \u3ci\u3eBaculovirus penaei\u3c/i\u3e
Tolerance of Baculovirus penaei virus to desiccation, pH, heat, and ultraviolet irradiation (uv), as well as its survival in 32 ppt sea water, was investigated using larval Penaeus vannamei in a bioassay. Test shrimp were sampled from 36 to 264 hr after food-borne exposure to treated B. penaei and examined for patent infections (polyhedral inclusion bodies detectable in fresh preparations of hepatopancreas) with light microscopy. B. penaei was completely inactivated within 30 min after exposure to pH 3, whereas exposure to pH 11 extended the prepatency period (period before infection is apparent) but did not inactivate the virus. B. penaei was inactivated by 10-min exposures to temperatures of 60–90°C. Ultraviolet irradiation for 40 min at a wavelength of 254 nm when B. penaei was 5 cm from the light source inactivated the virus (measured as a cumulative uv dosage of 7.08 × 106 μW ⋅ sec/cm2). Desiccation for 48 hr also inactivated the virus, and that method is the most practical to halt or prevent infections in some aquaculture facilities. B. penaei free from its host survived 32 ppt sea water at 22°C for 7 days and at 5°C for at least 14 days
Gauge Invariance in Chern-Simons Systems
We show explicitly that the question of gauge invariance of the effective
potential in standard scalar electrodynamics remains unchanged despite the
introduction of the Chern-Simons term. The result does not depend on the
presence of the Maxwell term in the Chern-Simons territory.Comment: 10 pages, Plain Tex, DF/UFPB-14/9
TorchAmi: Generalized CPU/GPU Implementation of Algorithmic Matsubara Integration
We present torchami, an advanced implementation of algorithmic Matsubara
integration (AMI) that utilizes pytorch as a backend to provide easy
parallelization and GPU support. AMI is a tool for analytically resolving the
sequence of nested Matsubara integrals that arise in virtually all Feynman
perturbative expansions. In this implementation we present a new AMI algorithm
that creates a more natural symbolic representation of the Feynman integrands.
In addition, we include peripheral tools that allow for import and labelling of
simple graph structures and conversion to torchami input. The code is written
in c++ with python bindings provided.Comment: 23pg, 5 figs. Code reference include
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