There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

Fast parallel algorithms for short-range molecular dynamics

抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

J. Appl. Cryst.の発刊に際して

/pdf/convex-analysisnoer-san-nojin-zhan-nituite-5dl2rbmoyr.pdf

Convex Analysisの二,三の進展について

We study the percolation aspects of diffusional "Coble" creep on heterogeneous grain boundary networks, assuming free grain boundary sliding. A novel percolation threshold is obtained for the honeycomb lattice when two representative types of grain boundaries are randomly distributed, p(cc)=0.5416+/-0.0036. The creep viscosity diverges near the percolation threshold with power-law exponents t=1.69+/-0.09 and s=1.88+/-0.12, different from the standard conduction and rigidity percolation exponents. The moments of both the force and flux distributions all conform to finite-size scaling at p(cc), but with new exponents. These new scaling behaviors seen in the creeping system are proposed to arise from the unique coupling of both force and flux balances in the network.

Percolation of diffusional creep: a new universality class.

Castable silicon-based compositions have enhanced toughness and related properties compared to silicon. The silicon-based compositions comprise silicon at a concentration greater than 50% by weight and one or more additional elements in structure comprising a cubic silicon phase and an additional phase which may impart toughness through mechanisms related to plastic flow or crack interaction with interfacial boundaries.

Silicon-rich alloys

Bipolar current electrodeposits a nanocrystalline grain size. Polarity Ratio relates the absolute value of time integrated amplitude of negative polarity and positive polarity current. Grain size can be controlled in alloys of two or more components, one of which being a metal, and one of which being most electro-active. Typically the more electro-active material is preferentially lessened in the deposit during negative current. The deposit is relatively crack and void free. Grain size is typically a function of deposit composition, which is typically a function of Polarity Ratio. Specified grain size can be achieved by selecting a corresponding Polarity Ratio. Coatings can be in layers, each having a grain size, which can vary layer to layer and also in a graded fashion. A finished article may be built upon a substrate of electro-conductive plastic, or metal, including steels, aluminum, brass. The substrate may remain, or be removed.

Method for producing alloy deposits and controlling the nanostructure thereof using negative current pulsing electro-deposition

Coble creep in heterogeneous materials: The role of grain boundary engineering

Grain boundary engineering (GBE) studies have demonstrated significant materials properties enhancements by modifying the populations and connectivity of different types of grain boundaries within the grain boundary network. In order to facilitate rigorous design and optimization of grain boundary networks, we develop theoretical tools that are based upon a spectral representation of grain boundary network statistics. We identify the connection between a local length scale, embodied by triple junctions, and a global length scale, associated with the grain boundary network configuration as a whole. We define the local state space for triple junctions, A ( 3 ) , and enumerate its symmetries. We further define the design space for grain boundary networks, M H ( 3 ) , characterize its important geometric properties, and discuss how its convexity permits grain boundary network design. We also investigate the extent to which the control of texture alone allows one to probe the full design space.

Christopher A. Schuh

Papers

Percolation of diffusional creep: a new universality class.

Silicon-rich alloys

Method for producing alloy deposits and controlling the nanostructure thereof using negative current pulsing electro-deposition

Coble creep in heterogeneous materials: The role of grain boundary engineering

The triple junction hull: Tools for grain boundary network design