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

Description of Four-Body Breakup Reaction with the Method of Continuum-Discretized Coupled-Channels

We present a method for smoothing discrete breakup $S$-matrix elements calculated by the method of continuum-discretized coupled-channels (CDCC). This smoothing method makes it possible to apply CDCC to four-body breakup reactions. The reliability of the smoothing method is confirmed for two cases, $^{58}$Ni($d$, $p n$) at 80 MeV and the $E1$ transition of $^6$He. We apply CDCC with the smoothing method to $^6$He breakup reaction at 22.5 MeV. Multi-step breakup processes are found to be important.Comment: 19 pages, 7 figures, published in Progress of Theoretical Physic

The X-ray Structure of A399 and A401: A Pre-Merging Cluster Pair

We present {\em ASCA} results of the pair clusters A399 and A401. The region between the two clusters exhibits excess X-rays over the value expected with a simple superposition of the two clusters. We see, however, no temperature rise at the merging front; the temperature is near the average of those in the inner regions of the two clusters. These indicate that the two clusters are really interacting but it is not strong at present. The inner regions of the two clusters show no radial variations of temperature, abundance and absorption values. We set upper-limits of mass deposition rate of cooling flow to be $\dot{M}<35\;\rm M_{\odot}yr^{-1}$ and $\dot{M}<59\;\rm M_{\odot}yr^{-1}$ for A399 and A401, respectively. A hint of azimuthal variation of the temperature is also found.Comment: 17 pages, 13 postscript figures, 2 external tables, accepted for publication in PAS