Weak universal critical behaviour of the mixed spin-(1/2, S) Ising model on the union jack (centered square) lattice: integer versus half-odd-integer spin-S case

The mixed spin-(1/2, S) Ising model on the union jack (centered square) lattice is investigated by establishing the mapping relationship with its corresponding eight-vertex model. An interplay between the nearest-neighbour interaction, the competing next-nearest-neighbour interaction and the single-ion anisotropy gives rise to a rather complex critical behaviour displayed in the reentrant phase transitions, the weak universal critical behaviour, as well as, a presence of first- and second-order phase transitions. The most interesting finding to emerge from the present study relates to a variation of the weak-universal critical exponents along the line of bicritical points, which is being twice as large for the mixed spin-(1/2, S) systems with the integer spin-S atoms as for the ones with the half-odd-integer spin-S atoms.Comment: 9 pages, 12 figure

Vicinal Surface with Langmuir Adsorption: A Decorated Restricted Solid-on-solid Model

We study the vicinal surface of the restricted solid-on-solid model coupled with the Langmuir adsorbates which we regard as two-dimensional lattice gas without lateral interaction. The effect of the vapor pressure of the adsorbates in the environmental phase is taken into consideration through the chemical potential. We calculate the surface free energy $f$, the adsorption coverage $\Theta$, the step tension $\gamma$, and the step stiffness $\tilde{\gamma}$ by the transfer matrix method combined with the density-matrix algorithm. Detailed step-density-dependence of $f$ and $\Theta$ is obtained. We draw the roughening transition curve in the plane of the temperature and the chemical potential of adsorbates. We find the multi-reentrant roughening transition accompanying the inverse roughening phenomena. We also find quasi-reentrant behavior in the step tension.Comment: 7 pages, 12 figures (png format), RevTeX 3.1, submitted to Phys. Rev.

Dynamical Properties of the Frustrated Ising Models and the Relation with the Ising Percolation Models

Characteristic properties of three kinds of dynamics (evolution on continuous time, heat bath method and Metropolis method) are discussed in the Ising model with three spins as a simple example by solving the master equation directly. The key problem to consider the relationship between dynamical properties such as "damage spreading" and properties of the corresponding Ising percolation model are pointed out

配向カーボンナノチューブ／ポリエチレン複合フィルムの電磁波減衰特性

博士（工学）doctoral創造科学技術大学院静岡大学甲第1110号ET

Morphological, ecological and molecular characterization of the enigmatic planispiral snail genus Adeuomphalus (Vetigastropoda : Seguenzioidea)

Adeuomphalus Seguenza, 1876 is a little known genus among the skeneimorph vetigastropods, with very few specimens previously reported alive from the deep sea. We examined newly collected and museum-stored specimens from upper to lower bathyal depths in the Atlantic, Mediterranean, Pacific and Indian Oceans and recognize seven recent species in the genus: A. ammoniformis Seguenza, 1876, A. densicostatus (Jeffreys, 1884), A. trochanter Waren & Bouchet, 2001, A. sinuosus (Sykes, 1925) n. comb., A. guillei n. sp., A. elegans n. sp. and A. collinsi n. sp., along with a fossil species, A. bandeli (Schroder, 1995) from the Lower Cretaceous, Poland. These species are characterized by a minute and colourless shell with almost perfectly planispiral whorls, an orthocline aperture, distinct radial ribs and a deeply concave apex and base. At least three species are confirmed to be radula-less, while A. guillei n. sp. has a simplified (3 2 1 2 3) rhipidoglossate radula. Anatomical investigations of A. collinsi n. sp. and A. trochanter revealed the following traits: a monopectinate ctenidium, blunt and tapering cephalic tentacles with sensory papillae, a cylindrical snout, a simple right neck lobe, a large foot with the anterior corners drawn out into finger-like projections, a smooth ESO-tentacle and a single, micropapillate epipodial tentacle on each side of the foot; absence of pigmented eyes, eye lobes, cephalic lappets and subocular peduncles. Three species collected by submersibles in the vicinity of hydrothermal vents co-occurred with carnivorous sponges of the family Cladorhizidae; a parasitic mode of life is suggested based on the lack of the radula and the peculiar, tube-like shape of the snout. Separate and combined phylogenetic analyses of mitochondrial (COI and 16S rRNA) and nuclear (histone H3 and 18S rRNA) gene sequences revealed six monophyletic groups in Seguenzioidea: Seguenziidae, Chilodontidae, Calliotropidae, Cataegidae, Spinicalliotropis and skeneimorph seguenzioids. Three included skeneimorphs (A. elegans n. sp., Xyloskenea sp. and Ventsia tricarinata) were ambiguously grouped together with long branches and low statistical supports, possibly suggesting a vast, undiscovered phylogenetic diversity of the group. Taxonomic composition, morphological characteristics and evolutionary history are discussed for the skeneimorphs and five other groups in the superfamily