944 research outputs found
Emergence of turbulence in an oscillating Bose-Einstein condensate
We report on the experimental observation of vortices tangle in an atomic BEC
of Rb-87 atoms when an external oscillatory perturbation is introduced in the
trap. The vortices tangle configuration is a signature of the presence of a
turbulent regime in the cloud. We also show that this turbulent cloud has
suppression of the aspect ratio inversion typically observed in quantum
degenerate bosonic gases during free expansion. Instead, the cloud expands
keeping the ratio between their axis constant. Turbulence in atomic superfluids
may constitute an alternative system to investigate decay mechanisms as well as
to test fundamental theoretical aspects in this field.Comment: accepted for Phys. Rev. Let
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From Rodeos to Indie Rock: The Economic and Fiscal Impacts of Selected Cultural Events in Denton, Texas
This report discusses the economic and fiscal impacts of selected cultural events in Denton, Texas
Route to turbulence in a trapped Bose-Einstein condensate
We have studied a Bose-Einstein condensate of atoms under an
oscillatory excitation. For a fixed frequency of excitation, we have explored
how the values of amplitude and time of excitation must be combined in order to
produce quantum turbulence in the condensate. Depending on the combination of
these parameters different behaviors are observed in the sample. For the lowest
values of time and amplitude of excitation, we observe a bending of the main
axis of the cloud. Increasing the amplitude of excitation we observe an
increasing number of vortices. The vortex state can evolve into the turbulent
regime if the parameters of excitation are driven up to a certain set of
combinations. If the value of the parameters of these combinations is exceeded,
all vorticity disappears and the condensate enters into a different regime
which we have identified as the granular phase. Our results are summarized in a
diagram of amplitude versus time of excitation in which the different
structures can be identified. We also present numerical simulations of the
Gross-Pitaevskii equation which support our observations.Comment: 6 pages, 3 figure
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Assessment of the Potential Fiscal Impacts of Existing and Proposed Transit-Oriented Development in the Dallas Area Rapid Transit Service Area
This report by the University of North Texas Center for Economic Development and Research gives an assessment of the fiscal impacts of transit-oriented development associated with development of the Dallas Area Rapid Transit (DART)light rail system. This analysis considers development near existing and planned light rail stations. The findings support the conclusion that the transit-oriented developments associated with DART Rail stations offer substantial fiscal impacts for local taxing entities
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The Healthcare Services Industry in Tarrant County: Industry Overview and Projected Employment Growth in Specified Occupations
The purpose of this report, by the University of North Texas Center for Economic Development and Research, is to offer an assessment of the current status of the healthcare services industry in Tarrant County. Also, to forecast demand for training in these specified occupations over the next several years
Controlled Anisotropic Deformation of Ag Nanoparticles by Si Ion Irradiation
The shape and alignment of silver nanoparticles embedded in a glass matrix is
controlled using silicon ion irradiation. Symmetric silver nanoparticles are
transformed into anisotropic particles whose larger axis is along the ion beam.
Upon irradiation, the surface plasmon resonance of symmetric particles splits
into two resonances whose separation depends on the fluence of the ion
irradiation. Simulations of the optical absorbance show that the anisotropy is
caused by the deformation and alignment of the nanoparticles, and that both
properties are controlled with the irradiation fluence.Comment: Submitted to Phys. Rev. Lett. (October 14, 2005
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The Current and Potential Economic and Fiscal Impacts of Texas' Moving Media Industry
This report compares the film industry incentive programs of other states with the Texas incentive program and examines their respective economic and fiscal impacts. In Texas, the economic impact of the moving media industry approached $345 million in 2007. This report also identifies strategies proposed to enhance Texas' future competitive position in the moving media industry
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Economic and Fiscal Impacts of DFW International Airport's Disadvantaged, Minority- and Women-Owned Business Enterprise: Detailed Findings and Updates
This report, by the University of North Texas Center for Economic Development and Research, updates the 2004/2005 analyses of the regional economic activity generated by Disadvantaged, Minority- and Women-Owned Business Enterprise (DMWBE) contractors and vendors operating at Dallas/Fort Worth International Airport (DFW Airport)
Three-vortex configurations in trapped Bose-Einstein condensates
We report on the creation of three-vortex clusters in a
Bose-Einstein condensate by oscillatory excitation of the condensate. This
procedure can create vortices of both circulation, so that we are able to
create several types of vortex clusters using the same mechanism. The
three-vortex configurations are dominated by two types, namely, an
equilateral-triangle arrangement and a linear arrangement. We interpret these
most stable configurations respectively as three vortices with the same
circulation, and as a vortex-antivortex-vortex cluster. The linear
configurations are very likely the first experimental signatures of predicted
stationary vortex clusters.Comment: 4 pages, 4 figure
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