Elastic properties of the Non-Fermi liquid metal CeRu4Sb12Ce Ru_4 Sb_{12} and the Dense Kondo semiconductor CeOs4Sb12Ce Os_4 Sb_{12}

We have investigated the elastic properties of the Ce-based filled skutterudite antimonides CeRu$_{4}$Sb$_{12}$ and CeOs$_{4}$Sb$_{12}$ by means of ultrasonic measurements. CeRu$_{4}$Sb$_{12}$ shows a slight increase around 130 K in the temperature dependence of the elastic constants $C$$_{11}$, ($C$$_{11}$-$C$$_{12}$)/2 and $C$$_{44}$. No apparent softening toward low temperature due to a quadrupolar response of the 4$f$-electronic ground state of the Ce ion was observed at low temperatures. In contrast CeOs$_{4}$Sb$_{12}$ shows a pronounced elastic softening toward low temperature in the longitudinal $C$$_{11}$ as a function of temperature ($T$) below about 15 K, while a slight elastic softening was observed in the transverse $C$$_{44}$ below about 1.5 K. Furthermore, CeOs$_{4}$Sb$_{12}$ shows a steep decrease around a phase transition temperature of 0.9 K in both $C$$_{11}$ and$C$$_{44}$. The elastic softening observed in $C$$_{11}$ below about 15 K cannot be explained reasonably only by the crystalline electric field effect. It is most likely to be responsible for the coupling between the elastic strain and the quasiparticle band with a small energy gap in the vicinity of Fermi level. The elastic properties and the 4$f$ ground state of Ce ions in CeRu$_{4}$Sb$_{12}$ and CeOs$_{4}$Sb$_{12}$ are discussed from the viewpoint of the crystalline electric field effect and the band structure in the vicinity of Fermi level.Comment: 9 pages, 11 figures, regular pape

The Virgo High-Resolution CO Survey. II. Rotation Curves and Dynamical Mass Distributions

Based on a high-resolution CO survey of Virgo spirals with the Nobeyama Millimeter-wave Array, we determined the dynamical centers using velocity fields, and derived position-velocity diagrams (PVDs) along the major axes of the galaxies across their dynamical centers. We applied a new iteration method to derive rotation curves (RCs), which reproduce the observed PVDs. The obtained high-accuracy RCs generally show steep rise in the central 100 to 200 pc regions, followed by flat rotation in the disk. We applied a deconvolution method to calculate the surface-mass density (SMD) using the RCs based on two extreme assumptions that the mass distribution is either spherical or thin-disk shaped. Both assumptions give nearly identical results, agreeing with each other within a factor of two at any radii. The SMD distributions revealed central massive cores with peak SMD of 10^4 - 10^5 Msun pc^-2 and total mass within 200 pc radius of the order of about 10^9 Msun Correlation analysis among the derived parameters show that the central CO-line intensity is positively correlated with the central SMD, which suggests that the deeper is the gravitational potential, the higher is the molecular gas concentration in the nuclei regardless morphological types.Comment: PASJ 2003 in press, Latex 12 pages, 6 figures (Bigger gif/ps figures available at http://www.ioa.s.u-tokyo.ac.jp/radio/virgo2

On the Composition of Gauge Structures

A formulation for a non-trivial composition of two classical gauge structures is given: Two parent gauge structures of a common base space are synthesized so as to obtain a daughter structure which is fundamental by itself. The model is based on a pair of related connections that take their values in the product space of the corresponding Lie algebras. The curvature, the covariant exterior derivatives and the associated structural identities, all get contributions from both gauge groups. The various induced structures are classified into those whose composition is given just by trivial means, and those which possess an irreducible nature. The pure irreducible piece, in particular, generates a complete super-space of ghosts with an attendant set of super-BRST variation laws, both of which are purely of a geometrical origin.Comment: Few elaborations are added to section 4 and section 5. To be published in Journal of Physics A: Mathematical and General. 21 page

Optical and CO Radio Observations of Poor Cluster Zwicky 1615.8+3505

The cluster Zwicky 1615.8+3505 is considered to be a dynamically young poor cluster. To investigate the morphology and star-formation activity of galaxies under the environment of a dynamically young poor cluster, we have performed V, R, and I surface photometry, optical low-resolution spectroscopy, and 12CO (J=1-0) line observations for member galaxies. Our data show that more than 90% of the observed galaxies show regular morphologies and no star-formation activities, indicating that the environment does not affect these galaxy properties. Among sixteen galaxies observed, only NGC 6104 shows a significant star-formation activity, and shows a distorted morphology, indicating a tidal interaction. This galaxy contains double knots, and only one knot possesses Seyfert activity, though the sizes and luminosities are similar to each other; we also discuss this feature.Comment: LaTeX manuscript (text.tex, use PASJ style files), four PS figures (fig[a-d].ps), and three PASJ style files. text.tex, figb.ps, and figd.ps are up-dated. To be appeared in The Publications of the Astronomical Society of Japan, Vol. 51, No. 3 (1999 June issue

There are no abnormal solutions of the Bethe−-Salpeter equation in the static model

The four-point Green's function of static QED, where a fermion and an antifermion are located at fixed space positions, is calculated in covariant gauges. The bound state spectrum does not display any abnormal state corresponding to excitations of the relative time. The equation that was established by Mugibayashi in this model and which has abnormal solutions does not coincide with the Bethe$-$Salpeter equation. Gauge transformation from the Coulomb gauge also confirms the absence of abnormal solutions in the Bethe$-$Salpeter equation.Comment: 11 pages, late

The Dog on the Ship: The "Canis Major Dwarf Galaxy" as an Outlying Part of the Argo Star System

Overdensities in the distribution of low latitude, 2MASS giant stars are revealed by systematically peeling away from sky maps the bulk of the giant stars conforming to ``isotropic'' density laws generally accounting for known Milky Way components. This procedure, combined with a higher resolution treatment of the sky density of both giants and dust allows us to probe to lower Galactic latitudes than previous 2MASS giant star studies. While the results show the swath of excess giants previously associated with the Monoceros ring system in the second and third Galactic quadrants at distances of 6-20 kpc, we also find a several times larger overdensity of giants in the same distance range concentrated in the direction of the ancient constellation Argo. Isodensity contours of the large structure suggest that it is highly elongated and inclined by about 3 deg to the disk, although details of the structure -- including the actual location of highest density, overall extent, true shape -- and its origin, remain unknown because only a fraction of it lies outside highly dust-obscured, low latitude regions. Nevertheless, our results suggest that the 2MASS M giant overdensity previously claimed to represent the core of a dwarf galaxy in Canis Major (l ~ 240 deg) is an artifact of a dust extinction window opening to the overall density rise to the more significant Argo structure centered at larger longitude (l ~ 290 +- 10 deg, b ~ -4 +- 2 deg).Comment: 4 pages, 4 figure

Nonlinear behavior of geometric phases induced by photon pairs

In this study, we observe the nonlinear behavior of the two-photon geometric phase for polarization states using time-correlated photons pairs. This phase manifests as a shift of two-photon interference fringes. Under certain arrangements, the geometric phase can vary nonlinearly and become very sensitive to a change in the polarization state. Moreover, it is known that the geometric phase for $N$ identically polarized photons is $N$ times larger than that for one photon. Thus, the geometric phase for two photons can become two times more sensitive to a state change. This high sensitivity to a change in the polarization can be exploited for precision measurement of small polarization variation. We evaluate the signal-to-noise ratio of the measurement scheme using the nonlinear behavior of the geometric phase under technical noise and highlight the practical advantages of this scheme.Comment: 10 pages, 10 figure

Metal-to-insulator transition in anatase TiO2 thin films induced by growth rate modulation

We demonstrate control of the carrier density of single phase anatase TiO2 thin films by nearly two orders of magnitude by modulating the growth kinetics during pulsed laser deposition, under fixed thermodynamic conditions. The resistivity and the intensity of the photoluminescence spectra of these TiO2 samples, both of which correlate with the number of oxygen vacancies, are shown to depend strongly on the growth rate. A quantitative model is used to explain the carrier density changes.Comment: 13 pages 3 figure

Heegaard genus, cut number, weak p-congruence, and quantum invariants

We use quantum invariants to define a 3-manifold invariant j_p which lies in the non-negative integers. We relate j_p to the Heegard genus, and the cut number. We show that j_$ is an invariant of weak p-congruence.Comment: to appear in JKTR. 8pages 1 figur