2,436 research outputs found
Program Notes for a Recital on March 21, 2015
During a recital on March 21, 2015, pieces by Hindemith, Bruckner, Bolter, Barat, Villa-Lobos, Dvořák, and Davis were performed on the trombone. This document will take an in depth look at each of these pieces in order to discuss the history, significance, and performance practice required to give an effective recital. Each chapter will have a different focus, ranging from the theory behind the composition, the idiomatic use of the trombone, operatic plots, and techniques used to perform vocal music on the trombone
New Critical Behavior in Einstein-Yang-Mills Collapse
We extend the investigation of the gravitational collapse of a spherically
symmetric Yang-Mills field in Einstein gravity and show that, within the black
hole regime, a new kind of critical behavior arises which separates black holes
formed via Type I collapse from black holes formed through Type II collapse.
Further, we provide evidence that these new attracting critical solutions are
in fact the previously discovered colored black holes with a single unstable
mode.Comment: 13 pages, 4 figure
Anomalously large measured thermoelectric power factor in SrLaTiO thin films due to SrTiO substrate reduction
We report the observation that thermoelectric thin-films of La-doped SrTiO3
grown on SrTiO3 substrates yield anomalously high values of thermopower to give
extraordinary values of power factor at 300K. Thin-films of Sr0.98La0.02TiO3,
grown via pulsed laser deposition at low temperature and low pressure (450C,
10-7Torr), do not yield similarly high values when grown on other substrates.
The thin-film growth induces oxygen reduction in the SrTiO3 crystals, doping
the substrate n-type. It is found that the backside resistance of the SrTiO3
substrates is as low (~12ohm/square) as it is on the film-side after film
growth.Comment: 12 pages, 3 figures, pdf forma
Quasi-states, quasi-morphisms, and the moment map
We prove that symplectic quasi-states and quasi-morphisms on a symplectic
manifold descend under symplectic reduction on a superheavy level set of a
Hamiltonian torus action. Using a construction due to Abreu and Macarini, in
each dimension at least four we produce a closed symplectic toric manifold with
infinite dimensional spaces of symplectic quasi-states and quasi-morphisms, and
a one-parameter family of non-displaceable Lagrangian tori. By using McDuff's
method of probes, we also show how Ostrover and Tyomkin's method for finding
distinct spectral quasi-states in symplectic toric Fano manifolds can also be
used to find different superheavy toric fibers.Comment: 22 pages, 7 figures; v3: minor corrections, added remarks, and
altered numbering scheme to match published version. To appear in
International Mathematics Research Notice
Towards the Final Fate of an Unstable Black String
Black strings, one class of higher dimensional analogues of black holes, were
shown to be unstable to long wavelength perturbations by Gregory and Laflamme
in 1992, via a linear analysis. We revisit the problem through numerical
solution of the full equations of motion, and focus on trying to determine the
end-state of a perturbed, unstable black string. Our preliminary results show
that such a spacetime tends towards a solution resembling a sequence of
spherical black holes connected by thin black strings, at least at intermediate
times. However, our code fails then, primarily due to large gradients that
develop in metric functions, as the coordinate system we use is not well
adapted to the nature of the unfolding solution. We are thus unable to
determine how close the solution we see is to the final end-state, though we do
observe rich dynamical behavior of the system in the intermediate stages.Comment: 17 pages, 7 figure
Numerical evidence for `multi-scalar stars'
We present a class of general relativistic soliton-like solutions composed of
multiple minimally coupled, massive, real scalar fields which interact only
through the gravitational field. We describe a two-parameter family of
solutions we call ``phase-shifted boson stars'' (parameterized by central
density rho_0 and phase delta), which are obtained by solving the ordinary
differential equations associated with boson stars and then altering the phase
between the real and imaginary parts of the field. These solutions are similar
to boson stars as well as the oscillating soliton stars found by Seidel and
Suen [E. Seidel and W.M. Suen, Phys. Rev. Lett. 66, 1659 (1991)]; in
particular, long-time numerical evolutions suggest that phase-shifted boson
stars are stable. Our results indicate that scalar soliton-like solutions are
perhaps more generic than has been previously thought.Comment: Revtex. 4 pages with 4 figures. Submitted to Phys. Rev.
Grid-Enabling a Vibroacoustic Analysis Application
This paper describes the process of grid-enabling a vibroacoustic analysis application using the Globus Toolkit 3.2.1. This is the first step in a project intended to grid-enable a suite of tools being developed as a service-oriented architecture for spacecraft telemetry analysis. Many of the applications in the suite are compute intensive and would benefit from significantly improved performance. In this paper we show the advantage of using Globus to grid-enable a single tool in a vibroacoustic analysis flow, with the result that using as few as eleven nodes, that tool’s runtime improved by a factor of eight. While communication overhead does affect performance, these results also indicate that coordinated communication and execution scheduling as part of workflow management would be able to significantly improve overall efficiency. In the larger context, our experience also shows that the service-oriented architecture approach, using grid computing tools, can provide a more flexible system design, in addition to improved performance and increased utilization of resources. We also provide some lessons learned in using the Globus Toolkit
The road to deterministic matrices with the restricted isometry property
The restricted isometry property (RIP) is a well-known matrix condition that
provides state-of-the-art reconstruction guarantees for compressed sensing.
While random matrices are known to satisfy this property with high probability,
deterministic constructions have found less success. In this paper, we consider
various techniques for demonstrating RIP deterministically, some popular and
some novel, and we evaluate their performance. In evaluating some techniques,
we apply random matrix theory and inadvertently find a simple alternative proof
that certain random matrices are RIP. Later, we propose a particular class of
matrices as candidates for being RIP, namely, equiangular tight frames (ETFs).
Using the known correspondence between real ETFs and strongly regular graphs,
we investigate certain combinatorial implications of a real ETF being RIP.
Specifically, we give probabilistic intuition for a new bound on the clique
number of Paley graphs of prime order, and we conjecture that the corresponding
ETFs are RIP in a manner similar to random matrices.Comment: 24 page
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