Cuntz-Pimsner C*-algebras associated with subshifts

By using C*-correspondences and Cuntz-Pimsner algebras, we associate to every subshift (also called a shift space) $X$ a C*-algebra $O_X$, which is a generalization of the Cuntz-Krieger algebras. We show that $O_X$ is the universal C*-algebra generated by partial isometries satisfying relations given by $X$. We also show that $O_X$ is a one-sided conjugacy invariant of $X$.Comment: 28 pages. This is a slightly updated version of a preprint from 2004. Submitted for publication. In version 2 the Introduction has been changed, two remarks (Remark 7.6 and 7.7) have been added and the list of references has been update

Stereoselective Synthesis of Optically Active Aspartic Acid from Derivatives of Fumaric Acid and Maleic Acid

Stereoselective synthesis of optically active aspartic acid from derivatives of fumaric acid and maleic aci

Stereoselective Syntheses of Optically Active Amino Acids from Methyl Esters of Alpha-keto Acids

Stereoselective syntheses of optically active amino acids from methyl esters of alpha-keto acid

Role of shocked accretion flows in regulating the QPO of galactic black hole candidates

Using a generalized non-spherical, multi-transonic accretion flow model, we analytically calculate the normalized QPO frequency ${\bar {\bf {\nu}}}_{qpo}$ of galactic black hole candidates in terms of dynamical flow variables and self-consistently study the dependence of ${\bar {\bf {\nu}}}_{qpo}$ on such variables. Our results are in fairly close agreement with the observed QPO frequencies of GRS 1915+105. We find that ${\bar {\bf {\nu}}}_{qpo}$ is quite sensitive to various parameters describing the black hole accretion flow containing dissipative and non-dissipative shock waves. Thus the QPO phenomena is, {\it indeed}, regulated by `shocked' black hole accretion, and, for the first time, we establish a definitive connection between the QPO frequency and the properties of advective BH accretion flows. This information may provide the explanation of some important observations of galactic micro quasars.Comment: Final version accepted for publication in the Astrophysical Journal Letters (ApJL). A considerable part of the paper is almost completely re-written, though the results and the final conclussions are the same. One can now ignore the previous version. 8 pages with four black and white figures. For high resolution Fig. 3, please mail the author <[email protected]

Angular and Abundance Distribution of High-energy Gamma Rays and Neutrons Simulated by GEANT4 Code for Solar Flares

In the solar flare observed on June 3, 2012, high energy gamma-rays and neutrons were observed. The event includes a remarkable feature of a high neutron/gamma-ratio in the secondary particles. We have examined whether this high n/$\gamma$-ratio can be explained by simulation. As a result of simulations using the GEANT4 program, the high n/$\gamma$-ratio may be reproduced for the case that helium and other heavy ions were dominantly accelerated in the flare.Comment: submitted to the Proceeding of The 20th International Symposium on Very High Energy Cosmic Ray Interaction (ISVHECRI 2018, Nagoya, Japan), Europian Physics Journa

Sunlight supply and gas exchange systems in microalgal bioreactor

The bioreactor with sunlight supply system and gas exchange systems presented has proved feasible in ground tests and shows much promise for space use as a closed ecological life support system device. The chief conclusions concerning the specification of total system needed for a life support system for a man in a space station are the following: (1) Sunlight supply system - compactness and low electrical consumption; (2) Bioreactor system - high density and growth rate of chlorella; and (3) Gas exchange system - enough for O2 production and CO2 assimilation