YMP 250Cray Y-MP/832


Three times the power and four times the memory of the Cray X-MP, this machine was next big thing in supercomputing.  The Y-MP retained software compatibility with the X-MP, but extended the address registers from 24 to 32 bits. High-density VLSI ECL technology was used and a new liquid cooling system was devised. The Y-MP ran the Cray UNICOS operating system.  The Y-MP could be equipped with two, four or eight vector processors, with two functional units each and a clock cycle time of 6 ns (167 MHz). Peak performance was thus 333 megaflops per processor. Main memory comprised 128, 256 or 512 MB of SRAM.

 The Y-MP was in use from 1989 to 1993.




 Structure of Proteins & DNA: Kinky DNA

John M. Rosenberg, University of Pittsburgh

Nearly everything that happens biologically from DNA happens because many different proteins somehow have the ability to isolate their activity at specific sites on the long helical strands that comprise DNA molecules. John Rosenberg uses the CRAY Y-MP to help understand these complex processes, usually called protein-DNA recognition.   Over more than 15 years, Rosenberg and his colleagues have carried on a sustained research effort aimed at understanding how protein-DNA recognition works in the case of a particular protein, Eco RI endonuclease. Using computational resources at the Pittsburgh Supercomputing Center, they have built a detailed model of the structure of Eco RI. Further computations also brought fundamental new understanding showing that a kink in DNA's structure is not inherent to DNA, as had been thought, but instead results from binding with Eco RI.


Death of a Hot Young Star: Modeling Gravitational Radiation from Stellar Core Collapse

Edward Seidel, Washington University, St. Louis

According to Einstein's general theory of relativity, a supernova could be a strong source of gravitational radiation.  It is one of the most massive objects we know of and it's a very violent process.  Working with Eric Myra of SUNY Stony Brook and Thomas Moore of Pomona College, Seidel developed a computer model that can predict gravitational emission from core collapse events--supernovae and black holes.  


The Tell-Tale Heart: Epicardial Potentials Solutions to the Inverse Problem in Electrocardiography

 Yoram Rudy, Barbara Messinger-Rapport & Howard Oster, Case Western Reserve University

Researchers at Case Western Reserve developed a technique to obtain epicardial potentials noninvasively.  Along with reducing the risk of open-heart surgery, this made it possible to use minimally-invasive, precise techniques like catheter ablation, in which electric current is applied through a fine plastic tube to destroy the abnormal tissue.  Using the CRAY Y-MP, Rudy and his colleagues were able to conduct theory-based simulations at the cellular level of how electrical impulses propagate in heart-muscle.  


The World According to GAUSSIAN: Developments in the Application of Molecular Orbital Theory

John A. Pople, Martin Head-Gordon & Douglas J. Fox 

Carnegie Mellon University

The Pople group used the recent enhancements to GAUSSIAN in developing a generalized methodology--a computational recipe--called "Gaussian-1 (G1) Theory." G1 is a composite method for accurately computing the total electronic and vibrational energy for a molecular system using (1) the Hartree-Fock ground -state geometry, (2) vibrational frequencies and (3) corrections to the electron-correlation energy.  The Pople group applied G! to a set of 31 experimentally-measured molecules and achieved their objective: energy results as accurate as experiment within two kilo calories per mole across the board.  


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