Supergravity Tensor Calculus in 5D from 6D

Supergravity tensor calculus in five spacetime dimensions is derived by dimensional reduction from the d=6 superconformal tensor calculus. In particular, we obtain an off-shell hypermultiplet in 5D from the on-shell hypermultiplet in 6D. Our tensor calculus still retains the dilatation gauge symmetry so that it becomes a trivial gauge fixing to make the Einstein term canonical in a general matter-Yang-Mills-supergravity coupled system.Comment: 38 pages, no figures, LaTeX, version to appear in PTP 104(2000),835-86

Off-shell d=5 Supergravity coupled to Matter-Yang-Mills System

We present an off-shell formulation of matter-Yang-Mills system coupled to supergravity in five dimensional space-time. We give an invariant action for the general system of vector multiplets and hypermultiplets coupled to supergravity as well as the supersymmetry transformation rules. All the auxiliary fields are kept un-eliminated so that the supersymmetry transformation rules remain unchanged even when the action is changed.Comment: 36 pages, no figures, LaTeX, version to appear in PTP 105(2001),323-35

ASCA Observation of the Lyman-limit Quasar PKS2145+067

X-ray observation of a famous Lyman-limit quasar PKS2145+067at z_em= 0.990 was carried with ASCA. The source showed a 2-10 keV flux of 1.3 E-11 erg cm^-2 sec^-1 (L_X = 2.5 E46 erg sec^-1 for H_0=50 km s^-1 Mpc^-1) described by a power-law spectrum with a photon index Gamma=1.63 +/- 0.04 . In the ASCA energy band, no excess absorption was detected implying the absorption column density at z_ ab=0.791 was less than 1.6 E21 cm^-2 if absorbing medium had a metal abundance of 0.5 solar. Comparison with previous Einstein and ROSAT observations shows that PKS2145+067 has increased its luminosity by a factor of 2--3 between 1991 and 1998.Comment: 15 pages, 3figures, Latex(PASJadd,sty, PASJ95.sty) accepted in PAS

"Indirect Network Effects and the Product Cycle: Video Games in the U.S., 1994-2002"

This paper examines the importance of indirect network effects in the U.S.video game market between 1994 and 2002. The diffusion of game systems is analyzed by the interaction between console adoption decisions and software supply decisions. Estimation results suggest that introductory pricing is an effective practice at the beginning of the product cycle, and expanding software variety becomes more effective later. The paper also finds a degree of inertia in the software market that does not exist in the hardware market. This observation implies that software providers continue to exploit the installed base of hardware users after hardware demand has slowed.

Anomalous magnetic properties near Mott transition in Kagom\'e lattice Hubbard model

We investigate the characteristics of the metallic phase near the Mott transition in the Kagom\'e lattice Hubbard model using the cellular dynamical mean field theory. By calculating the specific heat and spin correlation functions, we demonstrate that the quasiparticles show anomalous properties in the metallic phase close to the Mott transition. We find clear evidence for the multi-band heavy quasiparticles in the specific heat, which gives rise to unusual temperature dependence of the spin correlation functions.Comment: 2 pages, 3 figures, accepted for publication in J. Mag. Mag. Mater. (Proceedings of the ICM, Kyoto, Japan, August 2006

Detection of an X-Ray Hot Region in the Virgo Cluster of Galaxies with ASCA

Based on mapping observations with ASCA, an unusual hot region with a spatial extent of 1 square degree was discovered between M87 and M49 at a center coordinate of R. A. = 12h 27m 36s and Dec. = $9^\circ18'$ (J2000). The X-ray emission from the region has a 2-10 keV flux of $1 \times 10^{-11}$ ergs s$^{-1}$ cm$^{-2}$ and a temperature of $kT \gtrsim 4$ keV, which is significantly higher than that in the surrounding medium of $\sim 2$ keV. The internal thermal energy in the hot region is estimated to be $V n k T \sim 10^{60}$ ergs with a gas density of $\sim 10^{-4}$ cm$^{-3}$. A power-law spectrum with a photon index $1.7-2.3$ is also allowed by the data. The hot region suggests there is an energy input due to a shock which is probably caused by the motion of the gas associated with M49, infalling toward the M87 cluster with a velocity $\gtrsim 1000$ km s$^{-1}$.Comment: 12 pages, 3 figures, accepted to ApJ