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B. H. Wang, Y. F. Woo, P. M. Hui
Subject area: Statistical physics and thermodynamics.
1996 Volume 65 Issue 8 Pages
2345-2348
Published: August 01, 1996
Released on J-STAGE: October 01, 1999
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A mean field theory is proposed for two-dimensional (2D) traffic flowmodels.The theory takes into account the effects of overpasses and asymmetricdistribution of cars. The present theory represents a quantitativeimprovement over the previously reported mean field theoryby takinginto account the effects of blockages of cars moving in the same direction.Simulation results for asymmetric distributions of cars in the presence ofoverpasses are also presented.
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Yoshimi Tanaka, Koji Fukao, Yoshihisa Miyamoto, Hatsumi Nakazawa, Ken ...
Subject area: Mechanics, elasticity, and rheology.
1996 Volume 65 Issue 8 Pages
2349-2352
Published: August 01, 1996
Released on J-STAGE: October 01, 1999
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The morphology on fracture surfaces of polymer gels has been studied. Two kinds of macroscopic morphology were found depending on the crack growth rate. One is similar to the well-known river pattern and is observed at large crack growth rates and the other looks like fish scales and is observed at small crack growth rates. The change of the pattern indicates the existence of a dynamic transition. The introduction of water into the cracks in the gels increased the characteristic dimension of the regular patterns.
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Nobumitsu Yokoi
Subject area: The physics of plasmas and electric discharges.
1996 Volume 65 Issue 8 Pages
2353-2356
Published: August 01, 1996
Released on J-STAGE: October 01, 1999
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The effect of plasma rotation on suppression of magnetohydrodynamic(MHD) turbulence is studied using a turbulent dynamo model.This dynamo model consists of the equations for the turbulent MHDenergy, its dissipation rate, and the cross helicity, which aresolved numerically. The temporal evolutions of the turbulent MHDenergy and the turbulent cross helicity are compared between stateswith and without poloidal plasma rotation. It is shown that theturbulent MHD energy is greatly suppressed through the turbulentcross-helicity effect in the presence of poloidal plasma rotation.The cross-helicity production mechanism is also discussed.
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Tadao Kasuya
Subject area: Electron states in condensed matter.
1996 Volume 65 Issue 8 Pages
2357-2360
Published: August 01, 1996
Released on J-STAGE: October 01, 1999
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The cyclotron masses observed by the de Haas-van Alphen effect in semimetallic LaSb and particularly in small flat pockets in LaB
6, are substantially smaller than those evaluated by band calculations. As a common mechanism for low-carrier-density-systems, the mass reduction mechanism by the exchange interaction was first studied for an electron gas based on a simple model including Wigner crystal type screening. This model reproduces the result of high-density expansion and extends the result to the much lower density region of the Wigner liquid. The model was applied to the band electrons by dividing the band state into a plane wave part and a core part within a muffin-tin-sphere. It is shown that the mass reduction effect is enhanced particularly in the case of a small Fermi surface with strong anisotropy, which is in good agreement with the results obtained for the above materials.
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Yasuhiro Saiga, Yusuke Kato, Yoshio Kuramoto
Subject area: Electron states in condensed matter.
1996 Volume 65 Issue 8 Pages
2361-2364
Published: August 01, 1996
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A new anisotropic t-J model in one dimension is proposed which has long-range hopping and exchange. This t-J model is only partially solvable in contrast to known integrable models with long-range interaction. In the high-density limit the model reduces to the XXZ chain with the long-range exchange.Some exact eigenfunctions are shown to be of the Jastrow type if certain conditions for an anisotropy parameter are satisfied. The ground state as well as the excitation spectrum for various values of the anisotropy parameter and filling are derived numerically.It is found that the Jastrow-type wave function is an excellent trial function for any value of the anisotropy parameter.
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Ryuta Yagi, Takahide Yamaguchi, Shun–ichi Kobayashi
Subject area: Electronic transport in condensed matter.
1996 Volume 65 Issue 8 Pages
2365-2366
Published: August 01, 1996
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In a two-dimensional network of small tunneling junctions, the electric force lines are confined within the system. Therefore, the existence of the edge imposes an important condition on the interaction between charges in the system. We demonstrate the effect of the edge on in the temperature dependence of the resistance. With decreasing temperature, the resistance increases faster in narrower networks, while the tunneling resistance and charging energy are kept constant. The difference was larger than that expected from the calculations based on creation energy of charges and anticharges.
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Yoshio Shinoda, Keisuke Tajima
Subject area: Magnetic properties and materials.
1996 Volume 65 Issue 8 Pages
2367-2369
Published: August 01, 1996
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The kinetics of the first-order magnetic phase transition in Dy single crystal has been studied by the X-ray diffraction technique through the observation of the discontinuous change of the c lattice parameter. The phase transition has been found to be incomplete just below the Curie temperature and two magnetic phases coexist in a narrow temperature range. This result can be explained qualitatively by the nucleation and growth theory which includes the elastic energy of the stable phase owing to the pinning by defects of the crystal or impurities.
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Tomohiko Miyazaki, Daijiro Yoshioka
Subject area: Magnetic properties and materials.
1996 Volume 65 Issue 8 Pages
2370-2373
Published: August 01, 1996
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An antiferromagnetic Heisenberg model on a 1/5-depleted two-dimensional square lattice, a model of CaV_4O_9, is investigated by variational Monte Carlo simulation.A prototype of a trial wave function is obtained byprojecting out the doubly occupied statesfrom the Schwinger-boson mean-field solution.Then variational Monte Carlo simulation is performed forup to 40 × 40 sites (including 320 vacant sites).The optimized state has the lowest energy, -0.5510J, ever reported.For this state, energies of a dimer bond and a plaquette bond, the staggered magnetization, static structure factor, andexcitation spectrum are calculated.It is shown that the Néel order survives and there is no gapat isotropic coupling.
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Toshiya Inami, Yoshitami Ajiro, Tsuneaki Goto
Subject area: Magnetic properties and materials.
1996 Volume 65 Issue 8 Pages
2374-2376
Published: August 01, 1996
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High-field magnetization of two hexagonal layered compounds RbFe(MoO_4)_2 and CsFe(SO_4)_2 is measured. In the magnetization curves of both compounds, a plateau-like structure with one-third of the saturated moment is observed. This anomaly is analyzed in terms of the magnetization process of a two-dimensional triangular lattice Heisenberg antiferromagnet with weak Ising-type anisotropy.
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Hidetoshi Fukuyama, Naoto Nagaosa, Masako Saito, Tetsuhiro Tanimoto
Subject area: Magnetic properties and materials.
1996 Volume 65 Issue 8 Pages
2377-2380
Published: August 01, 1996
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Based on the phase Hamiltonian representation of a spin-1/2 Heisenberg two-leg ladder system coupled antiferromagnetically, which has a spin gap if clean, it is shown that a non-magnetic impurityreplacing a spin inducesa staggered spin modulation.This results in the long range order of antiferromagnetismin the presence of three-dimensional coupling between the ladders.This will be in accordance with a recent experimental observation byAzuma et al. on Sr(Cu
1-xZn
x)_2O_3.
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Mitsuru Fujii, Satoshi Fujimoto, Norio Kawakami
Subject area: Magnetic properties and materials.
1996 Volume 65 Issue 8 Pages
2381-2384
Published: August 01, 1996
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We study an integrable spin chain with an alternating array of spins S=1/2, 1 in external magnetic fields using the Bethe ansatz exact solution. The calculated magnetization curve has a cusp at a critical magnetic field H=H
C, at which the specific heat shows a divergence property.We also calculate finite-size corrections to the energy spectrum, and obtain the critical exponents of correlation functionsusing conformal field theory (CFT). Low-energy properties of the model are described by two c=1 U(1) CFTs at H
C and one c=1 U(1) CFT at H>HC.
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Manfred Sigrist, Akira Furusaki
Subject area: Magnetic properties and materials.
1996 Volume 65 Issue 8 Pages
2385-2388
Published: August 01, 1996
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Low-temperature thermodynamic properties of the spin-\frac12Heisenberg ladder system with non-magnetic impurities are discussedusing an effective Hamiltonian for the impurity-induced spins in thebackground of a spin liquid with a gap.It is shown that the uniform susceptibility shows Curie-like behaviorin high-, intermediate-, and low-temperature regimes, with threedifferent Curie constants. The ratio of specific heat to temperature, C/T, is divergent in the low-temperature limit, reflectinga singular distribution of the effectivecouplings among the impurity spins.
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Susumu Sasaki, Azusa Matsuda, C. W. Chu
Subject area: Magnetics resonances and relaxations in condensed matter; MÖssbauer effect.
1996 Volume 65 Issue 8 Pages
2389-2392
Published: August 01, 1996
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We report on a study of carbon thirteen (
13C) NMR spectra in a superconducting fulleride K
3C
60. It is found that the specra are reproduced as powder patterns of anisotropic NMR shifts. By analyzing the NMR shifts, the ratio of isotropic hyperfine coupling (A
isospin) of conduction electrons to anisotropic one (A
axspin) is obtained experimentally for the first time (A
isospin/A
axspin=0.78). The substantial isotropy is consistent with the crystal structure of the C
60 molecule. The contribution of carbon p π -orbitals to A
axspin is found to be dominant.
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Yuji Furukawa, Azusa Iwai, Ken–ichi Kumagai, Andrey Yakubovsky
Subject area: Magnetics resonances and relaxations in condensed matter; MÖssbauer effect.
1996 Volume 65 Issue 8 Pages
2393-2396
Published: August 01, 1996
Released on J-STAGE: October 01, 1999
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Using
31P-nuclear magnetic resonance (NMR), low-energy spin excitations are investigated in both (VO)_2P_2O_7 and VO(HPO_4)0.5H_2O, in which V
4+ (S=1/2) ions take ladder and dimer (isolated pair) configurations, respectively. Temperature (T) dependences of Knight shift (K) and nuclear spin-lattice relaxation time (T_1) in the two compounds show a thermally activated behavior originating from the spin gap formation in the low energy spin excitation. The most distinct difference appears in the T-dependence of (T_1TK)
-1 at low temperature, i.e., the T-independent behavior in the dimer system and the large decrease below the order of the spin gap in the ladder system. These experimental results suggest that the spin gap Δ is independent of wave vector q in the case of the dimer system, while Δ depends on q for the spin ladder system. Resonance frequency dependence of T_1 in the temperature regions of both T < Δ and T > Δ is also discussed.
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Hideo Iwase, Masahiko Isobe, Yutaka Ueda, Hiroshi Yasuoka
Subject area: Magnetics resonances and relaxations in condensed matter; MÖssbauer effect.
1996 Volume 65 Issue 8 Pages
2397-2400
Published: August 01, 1996
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The Knight shift (K) and the spin-lattice relaxation rate (1/T
1) at the V site of CaV
2O
5 have been measured by means of the pulsed-NMR technique in order to investigate the magnetic properties. By analyzing the temperature dependence of the spin susceptibility extracted from the Knight shift, it was clarified for the first time that the ground state of the spin system in CaV
2O
5 is a spin singlet state. Moreover, the energy gap between the ground state and the excited state was estimated to be about 500, K from the activation-like behavior of χ and 1/T
1. These results clearly indicate the existence of the spin gap in this material.
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Min–Kun Bae, Kazuhiro Hara, Hirotaka Okabe, Shoichi Kai, Yoshihi ...
Subject area: Dielectric properties and materials.
1996 Volume 65 Issue 8 Pages
2401-2403
Published: August 01, 1996
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Utilizing an atomic force microscope (AFM), we observed thecleavage surface of triglycine sulfate [TGS;(NH
2CH
2COOH)
3H
2SO
4]cleaved near Curie point in the atmosphere. Adoptingthe constant height mode in the repulsive force region, the contrast of lenticular domain patterns reversed forthe opposite direction scans parallel to the cleavage direction.The change in the contrast may result from the difference inthe frictional force due to the structure of the ferroelectricdomains on the cleavage surface.
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Hatsumi Nakazawa, Ken Sekimoto
Subject area: Biophysics.
1996 Volume 65 Issue 8 Pages
2404-2407
Published: August 01, 1996
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A theoretical model is presented for sorting of the polarity of actin filamentsin the presence of actin-activated ATP-hydrolysis of two-headed myosin (heavy meromyosin, HMM). In methyl-cellulose aqueous solution, actin filaments form a nonpolar bundlelike aggregate. Upon addition of HMM and ATP to this, the HMM-driven mutual sliding of the actin filaments is known to lead togradual segregation of the filaments according to their polarity directions, as well as to contraction of the length of the bundle.We found crucial role of frictional drag between the actin filaments, which is not mediated by active sliding forceof the two-headed myosins.We show why regions of actins withsorted polarity emerge and how they undergo coarsening in the presence of frictional drag between filaments.
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Demetris P. K. Ghikas, Sotiris N. Raptis
Subject area: Mathematical methods in physics.
1996 Volume 65 Issue 8 Pages
2409-2416
Published: August 01, 1996
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Applying the Painleve Test (P. T.) for Partial Differential Equations to the Hamilton-Jacobi equation of two-degree-of-freedom Hamiltonian Systems, a hierarchy of highly nonlinear equations satisfied by the potential function of these systems is derived. Using these equations as conditions for integrability we identify for a number of potentials of polynomial type (Henon-Heiles, Quartic and Sextic) critical parameter values for which the corresponding Hamiltonian Systems are Painleve Integrable (P. I.), (in the sense that they pass the P. T.). For a polynomial potential function which is not P. I. the conditions give precisely the parameter value for which the system has regular behavior (in terms of regular Poincare plots). Applying the first and simplest nonlihear equation to the Restricted Circular Three Body Problem (a non-polynomial potential function) we have an indication of the known stability region determined by the parameter μ where the critical value 0.0385 is impressively revealed. A direct attempt to solve the first equation of the hierarchy gave the obvious solution of a rotational invariant potential function and a new class of potentials which give regular scattering behavior. It is conjectured that other nontrivial solutions of this simple equation would give nontrivial classes of potential functions with regular behavior.
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A. C. Bryan, A. E. G. Stuart
Subject area: Mathematical methods in physics.
1996 Volume 65 Issue 8 Pages
2417-2422
Published: August 01, 1996
Released on J-STAGE: October 01, 1999
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The regularized long wave equation (RLW) was proposed as a model of the dynamics of long nonlinear surface waves with small amplitudes. The standard model in this domain is the Korteweg-de Vries equation (KdV) and it has been shown that these equations are predictively equivalent to the order of approximation used in their derivations. On the other hand, numerical computations indicate that the RLW has no multisoliton solutions and it is generally conjectured that it is not a soliton equation. In this paper we prove that the equation has no analytic two-soliton solutions.
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Hideaki Ujino, Miki Wadati
Subject area: Mathematical methods in physics.
1996 Volume 65 Issue 8 Pages
2423-2439
Published: August 01, 1996
Released on J-STAGE: October 01, 1999
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The Hi-Jack symmetric polynomials, which are associated with thesimultaneous eigenstates for the first and second conserved operators of thequantum Calogero model, are studied. Using the algebraic properties of theDunkl operators for the model, we derive the Rodrigues formula for the Hi-Jacksymmetric polynomials. Some properties of the Hi-Jack polynomials and the relationships with the Jack symmetric polynomials and with the basis given bythe QISM approach are presented.The Hi-Jack symmetric polynomials are strong candidatesfor the orthogonal basis of the quantum Calogero model.
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Jorge Fujioka, Aurea Espinosa
Subject area: Mathematical methods in physics.
1996 Volume 65 Issue 8 Pages
2440-2446
Published: August 01, 1996
Released on J-STAGE: October 01, 1999
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The stability of the bright-type algebraic solitary-wave solutions of two extended nonlinear Schrödinger (NLS) equations, recently obtained by Hayata and Koshiba (HK) [Phys. Rev. E 51 (1995) 1499], is investigated by means of the averaged Lagrangian variational technique. Concerning the first equation (a quadratic-cubic NLS eq.), the variational analysis shows that the exact solution found by HK is stable, as solitary-wave initial conditions which deviate from the HK solution evolve into oscillatory functions whose envelopes remain close to the exact solution, if certain stability conditions are satisfied. Concerning the second equation (a cubic-quintic NLS eq.), the variational analysis indicates that in this case the exact solution is unstable, as solitary-wave initial conditions which are higher than the exact solution lead to a blowup within a finite distance, whereas initial pulses which are lower than the exact solution are completely dispersed.
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Genzou Matsui
Subject area: Classical and quantum physics: mechanics and fields.
1996 Volume 65 Issue 8 Pages
2447-2454
Published: August 01, 1996
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A periodic Toda Lattice with impurity is investigated numerically. It isfound that there exist “resistant” periodic solutions for some specialvalues of the impurity mass. When perturbation and total energy becomesufficiently large, chaos is generated. However the resistant periodicsolutions do not disappear and two of them divide the chaos region into threesubregions which have different natures. Spatial coexistence of stationarychaos and nonstationary chaos is observed. Consequently, the existence ofsuch resistant periodic solutions suggests that solitonlike excitationspropagate without collapsing in media which include impurities.
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Kouichi Jimbo
Subject area: Electronic structure of atoms and molecules: theory.
1996 Volume 65 Issue 8 Pages
2455-2458
Published: August 01, 1996
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In the sheet plasma experiment, plasma potentials decreased but negative hydrogen ion currents increased toward the outside. The negative hydrogen ions are pushed inside by the electric field and are not coming out from the plasma unless an equilibrium exists somehow. A relation between negative hydrogen ion currents and plasma potentials is well explained by the one-dimensional Saha equation, from which the electron temperature 1.3, eV is obtained. This value is very close to the electron temperature 1, eV of the Langmuir method. A reasonable negative hydrogen ion density is also calculated from the equation. We conclude that electrons, hydrogen atoms and negative hydrogen ions are in equilibrium.
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Jun Onoe, Hirohide Nakamatsu, Takeshi Mukoyama, Rika Sekine, Hirohiko ...
Subject area: Electronic structure of atoms and molecules: theory.
1996 Volume 65 Issue 8 Pages
2459-2462
Published: August 01, 1996
Released on J-STAGE: October 01, 1999
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Bond overlap population has been applied to study the relativistic effects (contraction or expansion) on the bond length of CuH and AuH diatomic hydride molecules, using the nonrelativistic and relativistic DV-Xα molecular orbital methods. The relativistic bond length changes are estimated by comparing the dependence of the nonrelativistic and relativistic bond overlap population on the interatomic distance. The results thus obtained for the diatomic molecules are in good agreement with those estimated with the bonding energy calculations. The similar approach has been applied to the Au
2 and Pb
2 diatomic molecules. We have found that the positive and negative signs of the relativistic change in the bond overlap population at an experimentally determined bond length are useful to estimate whether the bond length is relativistically contracted or expanded.
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Yoichiro Furutani, Atsushi Fukuyama, Taro Hayashi
Subject area: Electronic structure of atoms and molecules: theory.
1996 Volume 65 Issue 8 Pages
2463-2471
Published: August 01, 1996
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We propose and analyze the two-temperature model of compressedatoms, immersed in a dense plasma, which is composed of an ion core inits ground state (T=0) and a clad electron gas at finitetemperatures. They are out of thermal equilibrium. The profiles ofthe electron density and the screening function within the atom arecalculated numerically on the basis of the variationalThomas-Fermi-Dirac-Weizsäcker equation. A limit of validity of themodel is also discussed.
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Shinobu Nakazaki, Masayuki Okahara, Yukikazu Itikawa
Subject area: Atomic and molecular collision processes and interactions.
1996 Volume 65 Issue 8 Pages
2472-2478
Published: August 01, 1996
Released on J-STAGE: October 01, 1999
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Electron-impact excitation of Ar
7+ isstudied theoretically with the R-matrix method.Excitation cross sectionsare calculated for the transitions from the ground state (3s) to the3p, 3d, 4s, 4p and 4d excited states at the impact electronenergies from threshold to 110 eV, allowing for coupling betweenthe lowest eleven states.All the cross sections show complicated resonancestructure. Differential cross sections (DCSs) are also calculated for the3s → 3p, 3d, 4s transitions both at the resonance andat the off-resonanceenergies. The DCS at the off-resonance position shows dominance ofbackward scattering.This is examined in more detail with the calculation of forward-backward asymmetry parameter. At the resonance, DCS changes its shape.This is shown at several selected resonant peaks. Thepresent theoretical cross sections well reproduce experimental dataavailable for the 3s → 3p transition.
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Mohamed A. K. El Adawi, El Sayed F. El Shehawey, Safaa A. Shalaby, Moh ...
Subject area: Fluid dynamics.
1996 Volume 65 Issue 8 Pages
2479-2484
Published: August 01, 1996
Released on J-STAGE: October 01, 1999
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Linear stability theory is applied to the problem of the natural convection that occurs in an inclined fluid layer with uniformly distributed internal heat sources and subjected to the action of a normal ac electric field. It is assumed that the two plates between which the fluid layer is confined are maintained at constant and equal temperature. Both the dielectric constant and density of the fluid are assumed to be functions of temperature. The power series method is used to obtain the eigenvalue equation which is then solved numerically to obtain the stable and unstable solutions.
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Nobutake Itoh
Subject area: Fluid dynamics.
1996 Volume 65 Issue 8 Pages
2485-2493
Published: August 01, 1996
Released on J-STAGE: October 01, 1999
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Linear stability analysis of the rotating-disk flow is made with a very simple model of disturbance equations consisting of the parallel-flow approximation and an additional term associated with the curvature of flow field. Numerical solutions of the resulting eigenvalue problem indicate the existence of two instabilities and reveal their entirely different mechanisms. One is the well-known cross-flow instability and the other is the instability due to the curvature of external streamlines, which was recently predicted to occur in three-dimensional boundary layers on a swept wing. The streamline-curvature mode is in fact identical with the classical one called `parallel' or `type 2' instability in atomospheric literature.
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Chi–Chuan Hwang, Jun–Liang Chen, Li–Fu Shen
Subject area: Fluid dynamics.
1996 Volume 65 Issue 8 Pages
2494-2501
Published: August 01, 1996
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Effects of insoluble surfactant on the dynamic rupture of a thin free filmare investigated. The integral method is applied to derive the strong nonlinearevolution equations. Then the numerical method is used to analyze the nonlinearrupture process. The results show that the Marangoni effect due to theconcentration gradient of insoluble surfactant delays the rupture process.Furthermore, the rupture time predicted by the evolution equations derived bythe integral theory is always longer than that predicted by the evolutionequations derived by the long-wave expansion method. Besides, it is shown thatthe stronger the Marangoni effect becomes, the larger the difference between therupture time predicted by both above two models becomes.
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J. Qian
Subject area: Fluid dynamics.
1996 Volume 65 Issue 8 Pages
2502-2505
Published: August 01, 1996
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Experimental values of the Kolmogorov constant Ko, translated from the experimentally measured one-dimensional (1-D) energy spectra of high-Reynolds-number turbulence, depend upon which form of the turbulence energy spectrum is used over the small scale range captured in the experiments. Most published experimental values of Ko ranges from 1.3 to 2.1, and are based upon a simple form of the energy spectrum which neglects the bump phenomenon. When improved forms of the energy spectrum, which take into account the bump phenomenon, are used, it is found that the experimental values of the Kolmogorov constant are between 0.9 and 1.5, much lower than most published experimental values.
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G. Dasgupta, N. Ghosh, N. Nandi, A. K. Chatterjee, S. Acharyya
Subject area: Kinetic and transport theory of fluids; physical properties of gases.
1996 Volume 65 Issue 8 Pages
2506-2513
Published: August 01, 1996
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The column calibration factor (CCF) F
s of a column (Roos and Rutherford 1969) has been accurately estimated to yield the thermal diffusion factor α
T's of Kr
80--Kr
86, Xe
129--Xe
136, CO
28--CO
29, CH
416--CH
417 and N
228--N
229 respectively at two different experimental temperatures. The probable temperature dependence of α
T's are used to obtain the force parameters ε
ij/k and σ
ij of the respective molecules. Again, the α
T's as obtained from lnq
max and F
s are compared with the experimental α
T's by the existing method involved with column shape factors as well as theoretical α
T's based on elastic and inelastic collisions among the molecules. The comparison of the estimated force parameters with the reported ones finally suggests the technique of predicting α
T's as a function of temperature is extremely useful.
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Minoru Fukui, Hirokazu Oikawa, Yoshihiro Ishibashi
Subject area: Kinetic and transport theory of fluids; physical properties of gases.
1996 Volume 65 Issue 8 Pages
2514-2517
Published: August 01, 1996
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Simulation has been performed for traffic flow in two-dimensional cellular automaton models including cars with unequal velocities: the northbound cars with a normal speed and the eastbound cars with a high speed. For the eastbound high speed cars, two models are considered. In the model I, the intrinsic velocity is defined for all eastbound cars. In the model II, the maximum velocity, acceleration and deceleration of the cars are taken into account. It has turned out that two new phases appear between the free-moving phase and the global jamming phase in both models. One is the one-sided blocking phase where the northbound cars block the high speed eastbound cars. Another is the mutual blocking phase where the cars on both roads are mutually blocked. The mean velocity of the cars and the size of the local jam are obtained.
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Ritoku Ando, Masaru Masuzaki, Hiroshi Morita, Ken–ichi Kobayashi ...
Subject area: The physics of plasmas and electric discharges.
1996 Volume 65 Issue 8 Pages
2518-2521
Published: August 01, 1996
Released on J-STAGE: October 01, 1999
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The production of a broadband microwave pulse from the interaction of an intense relativistic electron beam (IREB) with a plasma was studied experimentally. The beam-to-plasma density ratio (n
b/n
p) is an important parameter for the beam-plasma interaction. We found that there was an optimum value for n
b/n
p at which the power density was maximized. The optimum n
b/n
p was found to be --0.01, when varied in a range from 0.1 to 0.001. A brief consideration for the radiation intensity will be presented in this paper.
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Frank Verheest, Peter Meuris
Subject area: The physics of plasmas and electric discharges.
1996 Volume 65 Issue 8 Pages
2522-2525
Published: August 01, 1996
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Oblique low-frequency electromagnetic waves are treated in magnetizedplasmas with an arbitrary composition. The nonlinear evolution isdescribed by a Korteweg--de Vries equation, valid at all angles ofpropagation except strictly parallel propagation, for which a differentapproach is needed.
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Taira Suzuki
Subject area: Mechanical and acoustical properties of condesed matter.
1996 Volume 65 Issue 8 Pages
2526-2531
Published: August 01, 1996
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The quantum theory of dislocation dynamics has been worked out in order to interrelate the dislocation mobility and the strength of solid materials such as bcc iron and covalent-bonding silicon crystals. The theory is a continuation of the study on fcc copper, which has been published in 1995. The dislocation mobility in these materials is described in terms of resonant transfer of dislocations induced by a perturbation due to an externally applied shear stress. The present work has been able to derive successfully the yield strength from the dislocation mobility in all the materials investigated so far.
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Kêichiro Aizu
Subject area: Equations of state, phase equilibria, and phase transitions.
1996 Volume 65 Issue 8 Pages
2532-2535
Published: August 01, 1996
Released on J-STAGE: October 01, 1999
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Before this paper, ferroelectricity generated by undulated-prototypic to ferroic transition was abbreviated as U-ferroelectricity. This paper deals with U-ferroelectricity of type I and of f=2 (f denotes faintness index). A case study is made. The prototypic phase when homogeneous is assumed tetragonal. The order parameters are two real variables, Q
α and Q
β. The free energy function can be expanded into a power series in electric field, as Ψ=Φ-EΦ
′-(1/2)E
2Φ
′′-…, which defines Φ, Φ
′, etc. A theory is given; it clarifies that the combination of the following term within Φ (not Φ
′) and the following δ undulation is responsible for the generation of U-ferroelectricity:Term [Q
β(∂
xx2-∂
yy2)Q
α-Q
α(∂
xx2-∂
yy2)Q
β]and δ =Ucos (ĥx+\hat{θ})+U
′cos (ĥy+\hat{θ}
′).
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Hirotsugu Kobayashi, Makoto Katori
Subject area: Equations of state, phase equilibria, and phase transitions.
1996 Volume 65 Issue 8 Pages
2536-2542
Published: August 01, 1996
Released on J-STAGE: October 01, 1999
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We introduce a new model which shows the self-organizedcriticality (SOC). We call it the exclusive diffusion model, since if two or more than two particles are put on a site, they exclusivelydiffuse to different nearest-neighbor sites. It can be regarded as a modified process of the two-state model introduced byManna. By numerical simulations we evaluated the particle densities and various critical exponents in the SOC states for the squarelattice and the simple cubic lattice. The particle density of the exclusive diffusion model is differentfrom the value reported by Manna for the two-state model in twodimensions, while it is concluded that this model and the two-state model belong to the same universality class.We show that the mean-field approximation, which we proposed for thesandpile models in a previous paper, is also applicable to theexclusive diffusion model.
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Takashi Nishikawa, Yukio Yasui, Yoshiaki Kobayashi, Masatoshi Sato
Subject area: Thermal properties of condensed matter.
1996 Volume 65 Issue 8 Pages
2543-2547
Published: August 01, 1996
Released on J-STAGE: October 01, 1999
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Experimental studies on physical properties of the two dimensional strongly correlated electron system La
1.17-xSr_xVS
3.17 have been carried out.In the x region around 0.17, where the V-valency is --+3, the system is considered to be in a Mott insulating phase.With increasing x up to the region >~0.3, it becomes essentially metallic.Measurements of the thermal dilatation and the ultrasonic velocity have presented experimental evidence that a certain type of lattice distortion is involved in the phase transition observed previously by magnetic studies for samples with x--0.17.The electronic specific heat coefficient γ seems not to be enhanced as the system approaches the metal-insulator phase boundary from the metallic side.
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Tadao Kasuya
Subject area: Electron states in condensed matter.
1996 Volume 65 Issue 8 Pages
2548-2558
Published: August 01, 1996
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Physical mechanism in Kondo insulator with nearly homogeneous energy gap is studied based on the model for the valence fluctuation regime in which the mixing band electron is of localized character and the first excited state is a s-wave exciton. This model is applied to new experimental studies by the inelastic neutron scattering in SmB
6 and YbB
12, as well as their alloys. Therefore, the present model is based on the effective one site Kondo state model. The Luttinger theorem is also critically studied on this stand point. Detailed q-dependence of the s-wave exciton peak in SmB
6 is calculated based on the present model. Good agreement is obtained even though there is no adjustable parameter. In particular, two peak structure along both [111] and [011] directions with the intensity ratio of 3:1, as well as the sharp q dependences are explained very well. Anomalous behaviors in the alloy systems are also well explained based on the present model.
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Hisashi Kondo, Toru Moriya
Subject area: Electron states in condensed matter.
1996 Volume 65 Issue 8 Pages
2559-2563
Published: August 01, 1996
Released on J-STAGE: October 01, 1999
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Antiferromagnetic and metal to insulator transitions in the ground state of a two dimensional half-filled Hubbard model with the nearest neighbor and the second nearest neighbor transfers (-t and t
′, respectively) are studied by using the Hartree-Fock approximation. The results indicate that the phase diagram depends on the band structure or t
′/t ratio; a discontinuous transition between the paramagnetic metallic (PM) and the antiferromagnetic insulator (AI) phases takes place for t
′/t=0.2, while continuous transitions from PM to AM (antiferromagnetic metal) and then to AI phases take place for t
′/t=0.5. The results are compared with those of the Gutzwiller approximation and discussed in the light of the other existing theories. The general importance of considering antiferromagnetism in this problem is emphasized.
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Katsuyuki Matsunaga, Nobutaka Narita, Isao Tanaka, Hirohiko Adachi
Subject area: Electron states in condensed matter.
1996 Volume 65 Issue 8 Pages
2564-2570
Published: August 01, 1996
Released on J-STAGE: October 01, 1999
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The electronic states of F-centers in alkali halides with NaCl-type structure have been investigated using the discrete variational (DV) Xα cluster method. The electronic transition accompanied by optical absorption is examined on the basis of Slater's transition state concept. The photo-absorption energies of F-centers computed for the compounds with relatively small anions agree well with experimental data, but those for iodides and bromides exhibit much lower values than the observed values. We have also investigated the change in the absorption energy by the atom displacement. By the inward displacement of 1st neighbor cations, the absorption energies are decreased to approach the experimental values. The relaxation of the 1st neighbors estimated from the computation exhibits fairly small values in fluorides, while large values in iodides and bromides. The effect of lattice relaxation around an F-center is discussed in connection with the bonding nature of the F-center level.
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Yuichi Nemoto, Terutaka Goto, Shintaro Nakamura, Hideaki Kitazawa
Subject area: Electron states in condensed matter.
1996 Volume 65 Issue 8 Pages
2571-2576
Published: August 01, 1996
Released on J-STAGE: October 01, 1999
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The elastic constants of Kondo compound CePd
2Al
3 with a hexagonal crystal structure have been investigated by the ultrasonic measurement. In the present single crystal we have observed absence of long range order down to 0.5, K in applying field up to 120, kOe. The elastic softening of the transverse C
66 mode is ascribed to the quadrupolar response for the crystalline field state of CePd
2Al
3. The low temperature softenings of the longitudinal C
33 and C
11 modes below the Kondo temperature T
K-- 20, K are dominated by the Kondo singlet state.
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Shinichi Suzuki, Takuhiro Ogawa, Yoshikazu Suzumura
Subject area: Electron states in condensed matter.
1996 Volume 65 Issue 8 Pages
2577-2584
Published: August 01, 1996
Released on J-STAGE: October 01, 1999
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By making use of the periodic Anderson model with both the electron-phonon interaction and the transverse hopping, we examine the density of states at zero temperature for strongly correlated d electrons in DCNQI-Cu salt which undergoes a metal-insulator transition followed by three-fold periodicity of both a lattice distortion and a local spin. A slave-boson method is applied to the model expressed in terms of a hole picture in order to treat the local constraint strictly. There are both the coherent (band) component and the incoherent (localized) component in the metallic state. In the insulating state, all the electrons at the site with the local spin are incoherent and a small amount of both components remains at other sites.
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Kouichi Jouda, Satoshi Tanaka, Kouichi Ichikawa, Osamu Aita
Subject area: Electron states in condensed matter.
1996 Volume 65 Issue 8 Pages
2585-2589
Published: August 01, 1996
Released on J-STAGE: October 01, 1999
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3d X-ray photoemission, valence band X-ray photoemission and 5p → 3d X-ray emission spectra of PrF
3 and NdF
3 are investigated. The charge transfer energy, the effective hybridization and Coulomb interactions are evaluated by the theoretical analysis of these spectra. It is shown that all the experimental results are well reproduced by the theoretical calculation with a set of parameter values for each compound.It is found that parameter values of the charge transfer energy and effective hybridization systematically decrease in going from LaF
3 to NdF
3.
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Yasuyuki Aoki, Takashi Sambongi, Francis Levy, Helmut Berger
Subject area: Electronic transport in condensed matter.
1996 Volume 65 Issue 8 Pages
2590-2593
Published: August 01, 1996
Released on J-STAGE: October 01, 1999
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Thermopower and electrical resistivity of Hf /Te
2 and ZrTe
2, semi-metals with layered structure, were measured. The results on Hf /Te
2 are compared with the Hall coefficient by Klipstein et al. The electronic properties of Hf /Te
2 are interpreted in terms of a simple 2-band model. By analogy, the properties of ZrTe
2 are understood similarly.
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Takayuki Mizuno, Mikio Eto, Kiyoshi Kawamura
Subject area: Electronic transport in condensed matter.
1996 Volume 65 Issue 8 Pages
2594-2601
Published: August 01, 1996
Released on J-STAGE: October 01, 1999
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The Friedel sum rule is extended to express the electron numberaccumulated within an asymmetric potential wellin terms of the phases of transmission andreflection amplitudes of a double-barrier potential, in the presence of a bias voltage and charging effects.It is applied to study non-equilibrium transport propertiesin asymmetric double-barrier systems.The current-voltage characteristics dependson the sign of the bias voltage, which is caused by the different accumulation of chargesin the quantum well.Our self-consistent calculation shows the hysteresisin the current-voltage characteristicswhich agrees with the experimental observation.
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Jian–Xin Zhu, Z. D. Wang, Qianghua Wang
Subject area: Electronic transport in condensed matter.
1996 Volume 65 Issue 8 Pages
2602-2605
Published: August 01, 1996
Released on J-STAGE: October 01, 1999
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Based on a phenomenological model and taking into account the mutual inductance, we study the external magnetic flux dependence of persistent currents in a system of two electrically isolated mesoscopic rings. The possibility of a ground state with spontaneous magnetic flux trapped in the system is addressed. The analogy of the flux state in normal-metal rings and their superconducting counterparts is also discussed.
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Taro Nagao
Subject area: Electronic transport in condensed matter.
1996 Volume 65 Issue 8 Pages
2606-2609
Published: August 01, 1996
Released on J-STAGE: October 01, 1999
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Numerical simulations are performed on the electron transport throughrandom arrays of antidots in a magnetic field. Using the linear response theory, we reproduce two features which were clearly observed in experiments, that is, (1) disappearance of a peak in the magnetoresistivityof random antidot arrays and (2) anisotropy of the magnetoresistivities of anisotropically random arrays. Further we illustrate that the anisotropy isclosely related to the characteristic diffusion of the electron.
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Masakazu Ito, Masaki Mito, Tatsuya Kawae, Masako Hitaka, Kazuyoshi Tak ...
Subject area: Magnetic properties and materials.
1996 Volume 65 Issue 8 Pages
2610-2613
Published: August 01, 1996
Released on J-STAGE: October 01, 1999
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Magnetic susceptibility measurement has been carried out on the Haldane system (CH
3)
4NNi(NO
2)
3 containing non-magnetic Zn
2+ and magnetic Cu
2+ impurity ions. For each impure system, magnetic susceptibility is described by the sum of two contributions; one is from the Haldane state and the other is a paramagnetic contribution. The latter contribution increases proportionally with impurity concentration. For 1D system shortened by Zn
2+ impurity ions, the paramagnetic contribution obeys the Curie law, and its absolute value of the susceptibility is found to amount nearly 40\VBS model where the spin with its value S=1/2 appears at the both edges of 1D segments. In the case for the system with Cu
2+ impurity ions, the paramagnetic contribution is much smaller than the results for the Zn
2+ impure systems. This reduction of the magnetic moment of Cu
2+ ion for S=1/2 is qualitatively different from the case for the enhanced moment of Cu
2+ ion in the anisotropic S=1 Heisenberg antiferromagnet NENP.
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Shijo Nishigori, Hiroshi Goshima, Takashi Suzuki, Toshizo Fujita, Go N ...
Subject area: Magnetic properties and materials.
1996 Volume 65 Issue 8 Pages
2614-2623
Published: August 01, 1996
Released on J-STAGE: October 01, 1999
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Specific heat of single crystal of CeNiSn has been measured between 1.3 and 60, K and analyzed together with that of polycrystals of CeRhSb, CeNi
1-xPt
xSn (x=0.03, 0.06, 0.12 and 0.20) and CeNi
1-yCo_ySn (y=0.03 and 0.10). The magnetic specific heat divided by temperature C
m/T of CeNiSn and CeRhSb exhibits a maximum and substantially decreases at low temperatures indicating the energy gap opening in the heavy quasiparticle band. The Kondo temperatures T
K were estimated to be 51, K for CeNiSn and 89, K for CeRhSb by fitting the magnetic entropy S
m. Using the reduced temperature ˜{T}=T/T
K, C
m/T was plotted in C
m/˜{T} versus ˜{T}. The plot reveals the obvious relation between the energy gap formation and the Kondo effect.
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