104,336 research outputs found
Cosmic Strings, Zero Modes and SUSY breaking in Nonabelian N=1 Gauge Theories
We investigate the microphysics of cosmic strings in Nonabelian gauge
theories with N=1 supersymmetry. We give the vortex solutions in a specific
example and demonstrate that fermionic superconductivity arises because of the
couplings and interactions dictated by supersymmetry. We then use supersymmetry
transformations to obtain the relevant fermionic zero modes and investigate the
role of soft supersymmetry breaking on the existence and properties of the
superconducting strings.Comment: 12 pages, RevTex, submitted to Phys. Rev.
Computer aided processing using laser measurements
The challenge exists of processing the STS and its cargo through KSC facilities in the most timely and cost effective manner possible. To do this a 3-D computer graphics data base was established into which was entered the STS, payloads, and KSC facilities. The facility drawing data are enhanced by laser theodolite measurements into an as-built configuration. Elements of the data base were combined to study orbiter/facility interfaces payload/facility access problems and design/arrangement of various GSE to support processing requirements. With timely analysis/design utilizing the 3-D computer graphics system, costly delays can be avoided. Better methodology can be analyzed to determine procedures for cost avoidance
Enhanced backscatter of optical beams reflected in turbulent air
Optical beams propagating through air acquire phase distortions from
turbulent fluctuations in the refractive index. While these distortions are
usually deleterious to propagation, beams reflected in a turbulent medium can
undergo a local recovery of spatial coherence and intensity enhancement
referred to as enhanced backscatter (EBS). Using a combination of lab-scale
experiments and simulations, we investigate the EBS of optical beams reflected
from corner cubes and rough surfaces, and identify the regimes in which EBS is
most distinctly observed.Comment: 10 pages, 8 figure
Halogenation of microcapsule walls
Procedure for halogenation of confining walls of both gelatin and gelatin-phenolic resin capsules is similar to that used for microencapsulation. Ten percent halogen content renders capsule wall nonburning; any higher content enhances flame-retardant properties of selected internal phase material. Halogenation decreases permeability of wall material to encapsulated materials
Space environmental effects: Construction and utilization of a system to measure low thermal strain in one meter graphite epoxy tubes
A system for measuring the expansion of low coefficient of thermal expansion (CTE) materials was constructed around a H.P. 5526-A laser measuring system. The vacuum CTE measurements in the -150 F to +120 F range were made over a 6 month period on a graphite epoxy tube yielding CTE values of 2.5 to one fifty-millionth/F above ambient and 2 + or - one ten-millionth F below ambient temperature. To assure that the below ambient, approximately 10 microns high open loop nature of the delta L/L vs. T curves was not apparatus related, similar size quartz tubes (A and B) were checked and found to have only a 2 micron (negligable for quartz) open loop component. These two quartz tubes, A and B, had ambient CTE values 20% and 45% respectively higher than the average handbook value. The overnight microcreep diminished an order of magnitude during the first several cycles after the system had been reopened
Magnifying superlens in the visible frequency range
In this communication we introduce a new design of the magnifying superlens
and demonstrate it in the experiment.Comment: 3pages, 1 figur
Concepts relating magnetic interactions, intertwined electronic orders and strongly correlated superconductivity
Unconventional superconductivity (SC) is said to occur when Cooper pair
formation is dominated by repulsive electron-electron interactions, so that the
symmetry of the pair wavefunction is other than isotropic s-wave. The strong,
on-site, repulsive electron-electron interactions that are the proximate cause
of such superconductivity are more typically drivers of commensurate magnetism.
Indeed, it is the suppression of commensurate antiferromagnetism (AF) that
usually allows this type of unconventional superconductivity to emerge.
Importantly, however, intervening between these AF and SC phases, intertwined
electronic ordered phases of an unexpected nature are frequently discovered.
For this reason, it has been extremely difficult to distinguish the microscopic
essence of the correlated superconductivity from the often spectacular
phenomenology of the intertwined phases. Here we introduce a model conceptual
framework within which to understand the relationship between antiferromagnetic
electron-electron interactions, intertwined ordered phases and correlated
superconductivity. We demonstrate its effectiveness in simultaneously
explaining the consequences of antiferromagnetic interactions for the
copper-based, iron-based and heavy-fermion superconductors, as well as for
their quite distinct intertwined phases.Comment: Main text + 11 figure
Pneumatic separator gives quick release to heavy loads
Pneumatic separator, using applied pressure, quickly releases restraining devices securing heavy loads. With minor modifications this separator can be used as a coupling device
Quantum kinetic theory VII: The influence of vapor dynamics on condensate growth
We extend earlier models of the growth of a Bose-Einstein condensate to
include the full dynamical effects of the thermal cloud by numerically solving
a modified quantum Boltzmann equation. We determine the regime in which the
assumptions of the simple model are a reasonable approximation, and compare our
new results with those that were earlier compared with experimental data. We
find good agreement with our earlier modelling, except at higher condensate
fractions, for which a significant speedup is found. We also investigate the
effect of temperature on condensate growth, and find that this has a
surprisingly small effect.
The discrepancy between theory and experiment remains, since the speedup
found in these computations does not occur in the parameter regime specified in
the the experiment.Comment: Fourteen pages, TeX source with 11 figures. Changes : Extended
section on formalism to include a derivation of the ergodic Boltzmann
equation that we use, and a fuller explanation of the numerical methods.
Explained more fully the possible errors with the experimental data. Added
section detailing the source of possible errors in this formulation. Added
comparison of our work with the manuscript cond-mat/0001323, and some
analysis of the fits to the MIT growth curve
Classical Region of a Trapped Bose Gas
The classical region of a Bose gas consists of all single-particle modes that
have a high average occupation and are well-described by a classical field.
Highly-occupied modes only occur in massive Bose gases at ultra-cold
temperatures, in contrast to the photon case where there are highly-occupied
modes at all temperatures. For the Bose gas the number of these modes is
dependent on the temperature, the total number of particles and their
interaction strength. In this paper we characterize the classical region of a
harmonically trapped Bose gas over a wide parameter regime. We use a
Hartree-Fock approach to account for the effects of interactions, which we
observe to significantly change the classical region as compared to the
idealized case. We compare our results to full classical field calculations and
show that the Hartree-Fock approach provides a qualitatively accurate
description of classical region for the interacting gas.Comment: 6 pages, 5 figures; updated to include new results with interaction
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