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The recent discovery of a Gunn–Peterson (GP) trough in the spectrum of the redshift 6.28 SDSS quasar has raised the tantalizing possibility that we have detected the reionization of the universe. However, a neutral fraction (of hydrogen) as small as 0.1% is sufficient to cause the GP trough, hence its detection alone cannot rule out reionization at a much(More)
The normal parameters are a non–linear transformation of the cosmological parameters whose likelihood function is very well–approximated by a normal distribution. This transformation serves as an extreme form of data compression allowing for practically instantaneous calculation of the likelihood of any given model, as long as the model is in the parameter(More)
We present a method for reducing cosmological data to constraints on the amplitudes of modes of the dark energy density as a function of redshift. The modes are chosen so that 1) one of them has constant density and 2) the others are non-zero only if there is time-variation in the dark energy density and 3) the amplitude errors for the time-varying modes(More)
ACKNOWLEDGEMENTS First, I would like to thank my advisor, Prof. Scott Mahlke, for his continuous guidance and support. His encouragement, enthusiasm, and energy have kept me going at many critical moments of frustration during graduate school. He is always ready to discuss ideas and come up with interesting ways to tackle research problems. This(More)
Forty years ago Gene Amdahl published a figure of merit for parallel computation, which proved extremely controversial. The controversy still rages today, although those that have looked closely at this figure of merit conclude that it is correct, but perhaps misinterpreted. In this paper we will look at a small variation on that law that suggests computer(More)
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