5,839 research outputs found
Cosmic bulk viscosity through backreaction
We consider an effective viscous pressure as the result of a backreaction of
inhomogeneities within Buchert's formalism. The use of an effective metric with
a time-dependent curvature radius allows us to calculate the luminosity
distance of the backreaction model. This quantity is different from its
counterpart for a "conventional" spatially flat bulk viscous fluid universe.
Both expressions are tested against the SNIa data of the Union2.1 sample with
only marginally different results for the distance-redshift relation and in
accordance with the CDM model. Future observations are expected to be
able to discriminate among these models on the basis of indirect measurements
of the curvature evolution.Comment: 18 pages, 6 figures, comments and references added, accepted for
publication in GR
Self-localized impurities embedded in a one dimensional Bose-Einstein condensate and their quantum fluctuations
We consider the self-localization of neutral impurity atoms in a
Bose-Einstein condensate in a 1D model. Within the strong coupling approach, we
show that the self-localized state exhibits parametric soliton behavior. The
corresponding stationary states are analogous to the solitons of non-linear
optics and to the solitonic solutions of the Schroedinger-Newton equation
(which appears in models that consider the connection between quantum mechanics
and gravitation). In addition, we present a Bogoliubov-de-Gennes formalism to
describe the quantum fluctuations around the product state of the strong
coupling description. Our fluctuation calculations yield the excitation
spectrum and reveal considerable corrections to the strong coupling
description. The knowledge of the spectrum allows a spectroscopic detection of
the impurity self-localization phenomenon.Comment: 7 pages, 5 figure
Sympathetic cooling route to Bose-Einstein condensate and Fermi-liquid mixtures
We discuss a sympathetic cooling strategy that can successfully mitigate
fermion-hole heating in a dilute atomic Fermi-Bose mixture and access the
temperature regime in which the fermions behave as a Fermi liquid. We introduce
an energy-based formalism to describe the temperature dynamics with which we
study a specific and promising mixture composed of 6Li and 87Rb. Analyzing the
harmonically trapped mixture, we find that the favourable features of this
mixture are further enhanced by using different trapping frequencies for the
two species.Comment: 4 pages, 2 figure
Saturn IB Stage Launch Operations
The prelaunch and launch activities are described as they pertain to the S-IB (booster) stage of the 1.6 mi11ion-pound thrust Uprated Saturn Launch Vehicle. The typical over-all schedule for an Uprated Saturn Launch is presented, culminating in the launch, and concluding with analysis of the data returned. The launch vehicle is described, with a precis of the stages and the role each has in the performance of the mission. The paper is concerned with the testing performed to bring the composite parts of the launch vehicle to flight readiness status, with emphasis on the booster stage
Trap-assisted tunnelling and Shockley-Read-Hall lifetime of extended defects in In.53Ga.47As p+n junction
Several In.53Ga.47As p+n junctions with various extended defect densities (EDDs) have been grown by metalorganic vapor phase epitaxy (MOVPE), by carefully controlling the growth conditions. After fabrication, T-dependent J-V, C-V and double DLTS (DDLTS) are performed to extract the electrical field dependence of the extended defect levels. From this characterization, it is derived that the extended defects dominate the electrical field enhancement factor Gamma regardless of the value of the EDD and significantly increases the leakage current under reverse bias (i.e., decrease the Shockley-Read-Hall lifetime). These impacts are strongly connected to a "band-like" density of states of extended defects E2 at E-C-0.32 eV by comparing the DDLTS and T-dependent J-V characteristics. On the other hand, the reference sample (without EDs) surprisingly exhibits an even stronger field dependence with lower leakage current. Nevertheless, no straightforward candidate point defects can be found in this sample and the possible explanation are discussed
A resource-based analysis of the Gonzaga University men’s basketball program
In recent years, the Resource-Based View (RBV) of firms has been applied to strategic management in the context of sport. Numerous studies have examined the relationship between human resource management and athletic performance, as well as success in sport sponsorship. Other studies employed the RBV in the context of professional sports franchises and a major NCAA athletic program. This paper builds on previous research by using the RBV to show how the effective management of a strategic resource has led to a sustained competitive advantage for the Gonzaga University men’s basketball program. The key resource of the Gonzaga program is identified and evaluated in the context of the RBV, and the strategic decisions made to manage that resource and ultimately create a sustainable competitive advantage are discussed
Long-Range Capital Improvement Planning
Capital improvement planning provides a regular program for budgeting and fiscal planning. A 6-year plan provides the luxury of reflection rather than stamping out fires in the heat of disaster
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