104,026 research outputs found

    Cosmic Strings, Zero Modes and SUSY breaking in Nonabelian N=1 Gauge Theories

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    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

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    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

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    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

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    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

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    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

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    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

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    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

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    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

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    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

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    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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