2,703 research outputs found
Creating a functional musician: a performance workshop model
This paper examines the innovative re-alignment of one Australian tertiary music program in response to economic imperatives and a rapidly evolving marketplace. A 'functional musician' is technically sound, versatile, adaptive, collaborative, empathetic, creative, and capable of adapting to most professional situations. Conservatoire training models designed to produce classical musicians specialising in performance or education do not necessarily meet industry needs in twenty-first century Australia. Following changes to the secondary school music curriculum, undergraduate students are arriving at University with different musical skills. Responding to these changes, the University of Southern Queensland has adapted its tertiary classical music degree programs to create a new 'workshop model' for Music Practice courses to produce employable music graduates with adaptable skills suitable for the diverse Australian musical sector.
The new model had its initial implementation in semester 1 (February-June) 2012. Data was collected from two student surveys and from student reflective journals; it is intended that these form the beginning of a longitudinal survey. Analysis of the initial data indicates the workshop model is successful in many of its aims, but shows some areas needing refinement
Lyman-alpha transfer in primordial hydrogen recombination
Cosmological constraints from the cosmic microwave background (CMB)
anisotropies rely on accurate theoretical calculations of the cosmic
recombination history. Recent work has emphasized the importance of radiative
transfer calculations due to the high optical depth in the HI Lyman lines.
Transfer in the Lyman-alpha line is dominated by true emission and absorption,
Hubble expansion, and resonant scattering. Resonant scattering causes photons
to diffuse in frequency due to random kicks from the thermal velocities of
hydrogen atoms, and also to drift toward lower frequencies due to energy loss
via atomic recoil. Past analyses of Lyman-alpha transfer during the
recombination era have either considered a subset of these processes, ignored
time dependence, or incorrectly assumed identical emission and absorption
profiles. We present here a fully time-dependent radiative transfer calculation
of the Lyman-alpha line including all of these processes, and compare it to
previous results that ignored the resonant scattering. We find a faster
recombination due to recoil enhancement of the Lyman-alpha escape rate, leading
to a reduction in the free electron density of 0.45% at z=900. This results in
an increase in the small-scale CMB power spectrum that is negligible for the
current data but will be a 0.9 sigma correction for Planck. We discuss the
reasons why we find a smaller correction than some other recent computations.Comment: 16 pages, 7 figures, matches PRD accepted version. Fixed bug in
numerical transport code, resulting in slightly reduced effect on
recombination histor
VADER: A Flexible, Robust, Open-Source Code for Simulating Viscous Thin Accretion Disks
The evolution of thin axisymmetric viscous accretion disks is a classic
problem in astrophysics. While models based on this simplified geometry provide
only approximations to the true processes of instability-driven mass and
angular momentum transport, their simplicity makes them invaluable tools for
both semi-analytic modeling and simulations of long-term evolution where two-
or three-dimensional calculations are too computationally costly. Despite the
utility of these models, the only publicly-available frameworks for simulating
them are rather specialized and non-general. Here we describe a highly
flexible, general numerical method for simulating viscous thin disks with
arbitrary rotation curves, viscosities, boundary conditions, grid spacings,
equations of state, and rates of gain or loss of mass (e.g., through winds) and
energy (e.g., through radiation). Our method is based on a conservative,
finite-volume, second-order accurate discretization of the equations, which we
solve using an unconditionally-stable implicit scheme. We implement Anderson
acceleration to speed convergence of the scheme, and show that this leads to
factor of speed gains over non-accelerated methods in realistic
problems, though the amount of speedup is highly problem-dependent. We have
implemented our method in the new code Viscous Accretion Disk Evolution
Resource (VADER), which is freely available for download from
https://bitbucket.org/krumholz/vader/ under the terms of the GNU General Public
License.Comment: 58 pages, 13 figures, accepted to Astronomy & Computing; this version
includes more discussion, but no other changes; code is available for
download from https://bitbucket.org/krumholz/vader
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