3,637 research outputs found
Improved Ways to Compare Simulations to Data
Theoretical models for structure formation with Gaussian initial fluctuations
have been worked out in considerable detail and compared with observations on
various scales. It is on nonlinear scales \lsim 10 \ h^{-1}\ {\rm Mpc} that
the greatest differences exist between models that have been
normalized to agree on the largest scales with the COBE data; here especially
there is a need for better statistical tests which are simultaneously {\it
robust}, {\it discriminatory}, and {\it interpretable}. The era at which galaxy
and cluster formation occurs is also a critical test of some models. Needs for
the future include faster and cleverer codes, better control of cosmic variance
in simulations, better understanding of processes leading to galaxy formation,
better ways of comparing observational data with models, and better access to
observational and simulation data.Comment: 9 pages, self-extracting uuencoded postscript, encoded with uufile
Small employers and expanded health insurance coverage
New England states have been national leaders in developing and enacting health insurance programs. But as the new laws play out on real ground, various constituencies are seeing real or perceived devils in the detail of the expansion laws. For one group in particular—small employers—efforts to extend coverage have become a two-edged sword.Health care reform ; Small business ; Insurance, Health
Suppression of synchrotron radiation due to beam crystallization
With respect to a "hot", non-crystallized beam the synchrotron radiation of a
cold crystallized beam is considerably modified. We predict suppression of
synchrotron radiation emitted by a crystallized beam in a storage ring. We also
propose experiments to detect this effect.Comment: LaTeX, 3 pages, 1 figure, To be published in Eur. Phys. J. A,
December 199
Accelerating Dust Temperature Calculations with Graphics Processing Units
When calculating the infrared spectral energy distributions (SEDs) of
galaxies in radiation-transfer models, the calculation of dust grain
temperatures is generally the most time-consuming part of the calculation.
Because of its highly parallel nature, this calculation is perfectly suited for
massively parallel general-purpose Graphics Processing Units (GPUs). This paper
presents an implementation of the calculation of dust grain equilibrium
temperatures on GPUs in the Monte-Carlo radiation transfer code Sunrise, using
the CUDA API. The GPU can perform this calculation 69 times faster than the 8
CPU cores, showing great potential for accelerating calculations of galaxy
SEDs.Comment: 7 pages, 2 figures, accepted to New Astronomy. Minor updates to text
and performance based on feedback from refere
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