Henry M. Tufo

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The microbial mats of Guerrero Negro (GN), Baja California Sur, Mexico historically were considered a simple environment, dominated by cyanobacteria and sulfate-reducing bacteria. Culture-independent rRNA community profiling instead revealed these microbial mats as among the most phylogenetically diverse environments known. A preliminary molecular survey of(More)
We develop a fast direct solver for parallel solution of “coarse grid” problems, Ax = b, such as arise when domain decomposition or multigrid methods are applied to elliptic partial differential equations in d space dimensions. The approach is based upon a (quasi-) sparse factorization of the inverse of A. If A is n×n and the number of processors is P , the(More)
33 The Center for Astrophysical Thermonuclear Flashes at the University of Chicago—a collaboration between scientists primarily at Chicago and Argonne National Laboratory—studies the longstanding problem of thermonuclear flashes on the surfaces of compact stars (such as neutron stars and white dwarfs) and in the interior of white dwarfs (such as Type Ia(More)
In this paper, we examine parallel filesystems for shared deployment across multiple Linux clusters running with different hardware architectures and operating systems. Specifically, we deploy PVFS2, GPFS, Lustre, and TerraFS in our test environment containing Intel Xeon, Intel x86-64, and IBM PPC970 systems. We comment on the feature sets of each(More)
As the characteristic propagation speed is innnite for unsteady incompressible ows, solving for the pressure operator is the most computationally challenging phase of ow simulation. EEcient solution is dependent upon the availability of fast solvers for sparse linear systems. In this paper we develop an Schwarz preconditioner using overlapping subdomains(More)
We present simulations and performance results of nuclear burning fronts in supernovae on the largest domain and at the finest spatial resolution studied to date. These simulations were performed on the Intel ASCI-Red machine at Sandia National Laboratories using FLASH, a code developed at the Center for Astrophysical Thermonuclear Flashes at the University(More)