Matrix Model Approach to d>2d>2 Non-critical Superstrings

We apply light-cone quantization to a $1+1$ dimensional supersymmetric field theory of large N matrices. We provide some preliminary numerical evidence that when the coupling constant is tuned to a critical value, this model describes a 2+1 dimensional non-critical superstring.Comment: 11 pages, 3 Encapsulated Postscript figures. uses psfig.sty (available from http://xxx.lanl.gov/ftp/hep-th/papers/macros

Stationary quantum Markov process for the Wigner function

As a stochastic model for quantum mechanics we present a stationary quantum Markov process for the time evolution of the Wigner function on a lattice phase space Z_N x Z_N with N odd. By introducing a phase factor extension to the phase space, each particle can be treated independently. This is an improvement on earlier methods that require the whole distribution function to determine the evolution of a constituent particle. The process has branching and vanishing points, though a finite time interval can be maintained between the branchings. The procedure to perform a simulation using the process is presented.Comment: 12 pages, no figures; replaced with version accepted for publication in J. Phys. A, title changed, an example adde

String Scattering from D-branes in Type 0 Theories

We derive fully covariant expressions for all two-point scattering amplitudes involving closed string tachyon and massless strings from Dirichlet brane in type 0 theories. The amplitude for two massless D-brane fluctuations to produce closed string tachyon is also evaluated. We then examine in detail these string scattering amplitudes in order to extract world-volume couplings of the tachyon with itself and with massless fields on a D-brane. We find that the tachyon appears as an overall coupling function in the Born-Infeld action.Comment: 14 pages, latex, no figures, minor correction, reference adde

Strength evaluation test of pressureless-sintered silicon nitride at room temperature

In order to study strength characteristics at room temperature and the strength evaluating method of ceramic materials, the following tests were conducted on pressureless sintered silicon nitride specimens: bending tests, the three tensile tests of rectangular plates, holed plates, and notched plates, and spin tests of centrally holed disks. The relationship between the mean strength of specimens and the effective volume of specimens are examined using Weibull's theory. The effect of surface grinding on the strength of specimens is discussed

Explosive Nucleosynthesis in Axisymmetrically Deformed Type II Supernovae

Explosive nucleosynthesis under the axisymmetric explosion in Type II supernova has been performed by means of two dimensional hydrodynamical calculations. We have compared the results with the observations of SN 1987A. Our chief findings are as follows: (1) $^{44}Ti$ is synthesized so much as to explain the tail of the bolometric light curve of SN 1987A. We think this is because the alpha-rich freezeout takes place more actively under the axisymmetric explosion. (2) $^{57}Ni$ and $^{58}Ni$ tend to be overproduced compared with the observations. However, this tendency relies strongly on the progenitor's model. We have also compared the abundance of each element in the mass number range $A= 16-73$ with the solar values. We have found three outstanding features. (1) For the nuclei in the range $A=16-40$, their abundances are insensitive to the initial form of the shock wave. This insensitivity is favored since the spherical calculations thus far can explain the solar system abundances in this mass range. (2) There is an enhancement around A=45 in the axisymmetric explosion compared with the spherical explosion fairly well. In particular, $^{44}Ca$, which is underproduced in the present spherical calculations, is enhanced significantly. (3) In addition, there is an enhancement around A=65. This tendency does not rely on the form of the mass cut but of the initial shock wave. This enhancement may be the problem of the overproduction in this mass range, although this effect would be relatively small since Type I supernovae are chiefly responsible for this mass number range.Comment: 32 pages, 12 figures, LaTe

The Concentration-Density Relation of Galaxies in Las Campanas Redshift Survey

We report the results of the evaluation of the ``concentration-density'' relation of galaxies in the local universe, taking advantage of the very large and homogeneous data set available from the Las Campanas Redshift Survey (Shectman et al. 1996). This data set consists of galaxies inhabiting the entire range of galactic environments, from the sparsest field to the densest clusters, thus allowing us to study environmental variations without combining multiple data sets with inhomogeneous characteristics. Concentration is quantified by the automatically-measured concentration index $C$, which is a good measure of a galaxy's bulge-to-disk ratio. The environment of the sample galaxies is characterized both by the three-space local galaxy density and by membership in groups and clusters. We find that the distribution of C in galaxy populations varies both with local density and with cluster/group membership: the fraction of centrally-concentrated galaxies increases with local galaxy density, and is higher in clusters than in the field. A comparison of the concentration-local density relation in clusters and the field shows that the two connect rather smoothly at the intermediate density regime, implying that the apparent cluster/field difference is only a manifestation of the variation with the local density. We conclude that the structure of galaxies is predominantly influenced by the local density and not by the broader environments characterized by cluster/field memberships.Comment: 11 pages, 4 figures, ApJ in press, uses psfig.st