This book presents basic methods for numerical simulation of gravitational systems, demonstrating how to develop clear and elegant algorithms. It explains the fundamental mathematical tools needed to describe the dynamics of a large number of mutually attractive particles, and the techniques needed to model various known planetary and astrophysical phenomena.

Complex systems modeling and simulation approaches are being adopted in a growing number of sectors, including finance, economics, biology, astronomy, and many more. Technologies ranging from distributed computing to specialized hardware are explored and developed to address the computational requirements arising in complex systems simulations. The aim of this book is to present a representative overview of contemporary large-scale computing technologies in the context of complex systems simulations applications. The intention is to identify new research directions in this field and to provide a communications platform facilitating an exchange of concepts, ideas and needs between the scientists and technologist and complex system modelers. On the application side, the book focuses on modeling and simulation of natural and man-made complex systems. On the computing technology side, emphasis is placed on the distributed computing approaches, but supercomputing and other novel technologies are also considered.

This book constitutes the refereed post-conference proceedings of the 5th Russian Supercomputing Days, RuSCDays 2019, held in Moscow, Russia, in September 2019. The 60 revised full papers presented were carefully reviewed and selected from 127 submissions. The papers are organized in the following topical sections: parallel algorithms; supercomputer simulation; HPC, BigData, AI: architectures, technologies, tools; and distributed and cloud computing.

The 20th century saw tremendous achievements and progress in science and technology. Undoubtedly, computers and computer-related technologies acted as one of vital catalysts for accelerating this progress in the latter half of the century. The contributions of mathematical sciences have been equally profound, and the synergy between mathematics and computer science has played a key role in accelerating the progress of both fields as well as science and engineering. Mathematical sciences will undoubtedly continue to play this vital role in this new century. In particular, mathematical modeling and numerical simulation will continue to be among the essential methodologies for solving massive and complex problems that arise in science, engineering and manufacturing. Underpinning this all from a sound, theoretical perspective will be numerical algorithms. In recognition of this observation, this volume focuses on the following specific topics. (1) Fundamental numerical algorithms (2) Applications of numerical algorithms (3) Emerging technologies. The articles included in this issue by experts on advanced scientific and engineering computations from numerous countries elucidate state-of-the-art achievements in these three topics from various angles and suggest the future directions. Although we cannot hope to cover all the aspects in scientific and engineering computations, we hope that the articles will interest, inform and inspire members of the science and engineering community.

These are the proceedings of international conference on Numerical As trophysics 1998 (NAP98), held at National Olympic Memorial Youth Cen ter, in Tokyo, Japan in the period of March 10 - 13, 1998, and hosted by the National Astronomical Observatory, Japan (NAOJ). In the last decade numerical simulations have grown up as a major tool for astrophysics. Numerical simulations give us invaluable informa tion on complex systems and physical processes under extreme conditions which can be neither realized by experiments nor directly observed. Super computers and special purpose computers may work as very large telescopes and special purpose telescopes for theoretical astrophysics, respectively. Nu merical astrophysics ranks with other tool-oriented astronomy such as ra dio astronomy, infrared astronomy, ultraviolet astronomy, X-ray astronomy, and ')'-ray astronomy. This conference, NAP98, was planned to explore recent advances in astrophysics aided by numerical simulations. The subjects of the confer ence included the large-scale structure formation, galaxy formation and evolution, star and planets formation, accretion disks, jets, gravitational wave emission, and plasma physics. NAP98 had also sessions on numerical methods and computer science. The conference was attended by 184 sci entists from 21 countries. We enjoyed excellent talks, posters, videos, and discussions: there are 40 oral presentations, 96 posters and 16 video pre sentations. We hope that these proceedings and accompanying CD-ROM replay the friendly but inspiring atmosphere of the conference.

This volume contains working papers on astronomy and astrophysics prepared by 15 non-National Research Council panels in areas ranging from radio astronomy to the status of the profession.

This work focuses on the mechanism by which MreB contributes to the maintenance of cell shape in the gram-negative alpha-proteobacterium Caulobacter crescentus. The gene mreB encodes a protein that resembles actin, a eukaryotic cytoskeletal protein. Previously, it was shown that mreB is required to maintain a rod-like shape and localizes to a helical pattern near the cytoplasmic membrane. Here, we show that MreB is associated with regions of active growth in Caulobacter, as mutant strains that mislocalize MreB to the cell poles direct new growth at or near the poles. We present evidence to suggest that MreB contributes to the determination of proper length, width, and curvature through partially distinct mechanisms. The determination of proper width involves the essential proteins MreC and Pbp2, which are encoded in the mreB operon. While MreB and MreC are both required to position the cell wall transpeptidase Pbp2 along the lateral sidewalls and away from midcell, the two do not colocalize and each can maintain its localization in the absence of the other. When MreB is mislocalized to the poles, MreC and Pbp2 do not follow. These data argue against the idea that MreB provides a scaffold-like structure to localize enzymes that directly modify the cell wall. The determination of proper curvature, involves the intermediate filament-like protein, Crescentin. We identify a putative binding site on MreB for Crescentin or other curvature-mediating factors. We also show that the extent to which the subcellular localization of MreB changes over the cell cycle is correlated with cell size, indicating that MreB is involved in the coordination between elongation and division. In addition, we show that in vitro purified MreB spontaneously forms very stable polymers in the presence or absence of nucleotide. These polymers are globular or amorphous and only filamentous when placed on a highly positively charged surface of Poly-L-lysine. These in vitro data suggest that MreB is likely to be regulated at the disassembly step in the cell and that the cellular environment may influence the structure of MreB polymers. Lastly, we present biochemical evidence to support the existence of a disassembly factor in cytoplasmic Caulobacter extract. Together our data suggest that the maintenance of the crescent-rod cell shape in Caulobacter is the result of a complicated balance between MreB's dynamic subcellular localization, polymeric structure, and communication with cellular components.