Michael Pitman

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This paper describes a novel spatial-force decomposition for N-body simulations for which we observe O(sqrt(p)) communication scaling. This has enabled Blue Matter to approach the effective limits of concurrency for molecular dynamics using particle-mesh (FFT-based) methods for handling electrostatic interactions. Using this decomposition, Blue Matter(More)
This paper presents strong scaling performance data for the Blue Matter molecular dynamics framework using a novel n-body spatial decomposition and a collective communications technique implemented on both MPI and low level hardware interfaces. Using Blue Matter on Blue Gene/L, we have measured scalability through 16,384 nodes with measured time per(More)
We describe the dynamic behavior of a 1-stearoyl-2-oleoyl-phosphatidylethanolamine (SOPE) bilayer from a 20 ns molecular dynamics simulation. The dynamics of individual molecules are characterized in terms of (2)H spin-lattice relaxation rates, nuclear overhauser enhancement spectroscopy (NOESY) cross-relaxation rates, and lateral diffusion coefficients.(More)
by the IBM Blue Gene team: F. Allen, G. Almasi, W. Andreoni, D. Beece, B. J. Berne, A. Bright, J. Brunheroto, C. Cascaval, J. Castanos, P. Coteus, P. Crumley, A. Curioni, M. Denneau, W. Donath, M. Eleftheriou, B. Fitch, B. Fleischer, C. J. Georgiou, R. Germain, M. Giampapa, D. Gresh, M. Gupta, R. Haring, H. Ho, P. Hochschild, S. Hummel, T. Jonas, D. Lieber,(More)
Rhodopsin, the G protein-coupled receptor primarily responsible for sensing light, is found in an environment rich in polyunsaturated lipid chains and cholesterol. Biophysical experiments have shown that lipid unsaturation and cholesterol both have significant effects on rhodopsin's stability and function; omega-3 polyunsaturated chains, such as(More)
Cholesterol's preference for specific fatty acid chains is investigated at the atomic level in a 20 ns molecular dynamics computer simulation of a lipid bilayer membrane consisting of cholesterol and 1-stearoyl-2-docosahexaenoyl-sn-glycero-3-phosphocholine (SDPC) in a 1:3 ratio. These simulations reproduce experimental measurements suggesting that(More)
An unresolved question about GPCR function is the role of membrane components in receptor stability and activation. In particular, cholesterol is known to affect the function of membrane proteins, but the details of its effect on GPCRs are still elusive. Here, we describe how cholesterol modulates the behavior of the TM1-TM2-TM7-helix 8(H8) functional(More)
We present the Active Storage Fabrics (ASF) model for storage embedded parallel processing as a way to address petascale data intensive challenges. ASF is aimed at emerging scalable system-on-a-chip, storage class memory architectures, but may be realized in prototype form on current parallel systems. ASF can be used to transparently accelerate host(More)
We present a 118-ns molecular dynamics simulation of rhodopsin embedded in a bilayer composed of a 2:2:1 mixture of 1-stearoyl-2-docosahexaenoyl-phosphatidylcholine (SDPC), 1-stearoyl-2-docosahexaenoyl-phosphatidylethanolamine (SDPE), and cholesterol, respectively. The simulation demonstrates that the protein breaks the lateral and transverse symmetry of(More)