Showing papers by "Osaka University published in 1972"

An algorithm for computing the capacity of arbitrary discrete memoryless channels

Abstract: A systematic and iterative method of computing the capacity of arbitrary discrete memoryless channels is presented. The algorithm is very simple and involves only logarithms and exponentials in addition to elementary arithmetical operations. It has also the property of monotonic convergence to the capacity. In general, the approximation error is at least inversely proportional to the number of iterations; in certain circumstances, it is exponentially decreasing. Finally, a few inequalities that give upper and lower bounds on the capacity are derived.

Crystal Structures of Three Crystalline Forms of Poly(vinylidene fluoride)

Abstract: The crystal structures of three forms of poly(vinylidene fluoride) were studied by X-ray diffraction method. Although the structure of form I has been determined to be a fully extended planar zigzag by Lando, et al. [orthorhombic; a=8.58 A, b=4.91 A, and c(fiber axis)=2.56 A; space group Cm2m(C2v14)], an alternately-deflected molecular structure was postulated in order to release the steric hindrance between the fluorine atoms along the chain. A satistically disordered packing of such deflected chains satisfies the observed fiber period and improves appreciably the structure factor agreement. Form II is monoclinic [pseudo-orthorhombic; a=4.96 A, b=9.64 A, c(fiber axis)=4.62 A, and β=90°; space group P21/c(C2h5)], and its cell contains two molecular chains. The molecular conformation is essentially the TGTG type (internal rotation angles, 179° and 45°), and the glide plane of the molecular chain coincides with the c glide plane of the lattice. It is suggested that form III is monoclinic [a=8.66 A, b=4.93 A, c(fiber axis)=2.58 A, and β=97°; space group C121(C23)], and the structural features similar to that of form I.

One-Dimensional Anisotropic Heisenberg Model at Finite Temperatures

Abstract: The thermodynamics of the one-dimensional Heisenberg-Ising model for I.JI<1 as well as of the X-Y-Z model is reduced to a set of non-linear integral equations under some plausible assumptions. It is remarkable that the number of unknown functions involved in them becomes finite when rr/cos-1.J is a rational number for the Heisenberg-Ising model and when Kz/t; is a rational number for the X-Y-Z model (where coupling constants J"', Ju and J. are parametrized by f;, l, and J. as J:c=J. en (2t;,l) and Jy=J. dn (2t;,l); 12l20, K!22C20, and K 1 is the complete elliptic integral· of the first kind of modulus l). The validity of our theory has been confirmed by the high-temperature expansion of the free energy through the second term for a general value of .J and through the fourth term for .J=!.

Molecular Conformation and Packing of Poly(vinylidene fluoride). Stability of Three Crystalline Forms and the Effect of High Pressure

Abstract: The formation of three crystalline forms of poly(vinylidene fluoride) was studied in detail by using an apparatus for heat treatments under high pressure up to 5000 atm. Form II consisting of TGTG-type molecular chains was the most stable under atmospheric pressure, and form I, composed of planar zigzag-type chains, was formed under special conditions, such as tension, high pressure, etc. Form III may be an intermediate modification between I and II. Based upon these experimental facts, as well as the potential energy calculations of the intra- and intermolecular interactions in the crystal lattices due to the van der Waals and electrostatic forces, the relation between the conditions of formation of the three forms and their structures was examined. The planar zigzag-type conformation (in forms I and III) is considered to be less stable than the TGTG type (form II) because of the steric hindrances and electrostatic dipole interactions. In spite of the difference in the intramolecular potential energy between these two molecular conformations, the stabilities of the three crystalline forms are not so very different because of the more favorable intermolecular interaction in form I.

Direct phase detecting system.

Abstract: A system for extracting the phase components of an optical traveling wave field has been constructed. This system consists of the Mach-Zehnder interferometer to capture the wave field as the hologram, a photoelectronic scanning system, and an analog computing circuit. The detected phase signal is immediately displayed on a cathode ray tube as continuous-tone patterns. The method has been confirmed through the experimental results.

Calculation of Electronic Structure of Fe Base bcc Ferromagnetic Alloys in the Coherent Potential Approximation

Abstract: The electronic structure of Ni base ferromagnetic alloys with Co, Fe, Mn and Cr is discussed on the basis of the coherent potential approximation combined with the Hartree-Fock approximation for the electron-electron interaction. Calculations are carried out by use of a tight-binding single band model. With consistent choices of parameters the concentration dependences of the average magnetic moment of each constituent atom, the saturation magnetization, and the density of states at the Fermi level are calculated. The significance and limit of the coherent potential approximation for calculating the electronic structure of the ferromagnetic alloys are discussed in some detail.

A Microscopic Theory on the Phase Transitions in NH 4 Br —An Ising Spin Phonon Coupled System—

Abstract: CsCl type NH 4 Br crystal has been treated as an Ising spin-phonon coupled system to explain the phase transitions associated with the orientational order of NH 4 + ions. The appearance of two ordered phases is explained as essentially due to the fact that the direct interaction between NH 4 + ions stabilizes parallel ordering while the indirect interaction through phonons stabilizes the antiparallel ordering. Based on a microscopic hamiltonian describing the spin-phonon coupled system, several experimental results have been analized such as (i) anomalous lattice expansions (ii) orientational order parameters (iii) spontaneous displacement of Br - ions (iv) P - T phase diagram (v) X-ray critical diffuse scattering. Semiquantitative agreements are obtained. Especially the property of correlated fluctuations of displacement of Br - ions seems to give a support on the validity of the microscopic model used.

A Theory of the Cooperative Jahn-Teller Effect —Crystal Distortions in Cu 1-x Ni x Cr 2 O 4 and Fe 1-x Ni x Cr 2 O 4 —

Abstract: A theory of the cooperative Jahn-Teller effect is developed for the purpose of discussing the spontaneous crystal distortions in mixed chromites, Cu 1- x Ni x Cr 2 O 4 and Fe 1- x Ni x Cr 2 O 4 The static Jahn-Teller effect only is taken into account The theory separates the self-energy of each ion having a degenerate orbital level from those energies which contribute to the cooperative phenomenon; the former energy represents the effect of a local distortion which persists in the cubic phase The theory also distinguishes between the contributions of the Jahn-Teller coupling with the bulk strains and with relative displacements of ions The theory explains successfully various features of the phase diagrams of the mixed chromites such as the concentration dependences of the transition temperatures and the magnitudes of the distortions, the appearance of an orthorhombic phase, etc The temperature dependence of elastic moduli is also discussed to point out that it will yield additional informations, pa

Lipids in the nervous system of different species as a function of age: brain, spinal cord, peripheral nerve, purified whole cell preparations, and subcellular particulates: regulatory mechanisms and membrane structure.

Abstract: Publisher Summary The importance of lipid metabolism in health and disease has made a better knowledge of lipid metabolism and enzymology necessary. The lipid composition of whole organs and isolated subcellular particulates has become of great importance to those who study cell membranes. Membranology has become the common meeting ground for many chemists and biologists with different types of specialized training and experience. The lipid composition of the major organs of some species of higher animals has been defined with considerable accuracy. The study of subcellular articulates requires their isolation and characterization as well as their lipid analysis. This chapter presents the data that is relevant to the changes with age and species variations of the lipid composition of the nervous system. It also presents a scheme for membrane biosynthesis and a model for membrane structure; it considers the factors that determine the lipid class composition of membranes.

Role of microexudate carpet in cell division.

Abstract: THE growth rate of cells isolated from higher organisms depends largely on population density. At low cell densities, cells have a low probability of growing in usual culture conditions (reviewed in ref. 1). Cell growth can be sustained in sparse cultures using X-irradiated feeder layers or conditioned medium. Feeder layers are thought to enhance growth by producing “conditioned factor”, which seems to be restricted to the vicinity of feeder cells2–4, and is hardly diffusible into culture medium. Conditioned factor was supposed to be a kind of pericellular substance such as microexudate, which was detected by Rosenberg5 by using ellipsometry. While similar substances have been observed for several types of cultured cells6,7, little has been known about their chemical, morphological and biological properties. We have examined the microexudate carpet by electron microscopy after improving the sectioning technique for monolayer cultures of chick embryo cells.

PHASE TRANSFORMATIONS OF PURE Mg2SiO4 INTO A SPINEL STRUCTURE UNDER HIGH PRESSURES AND TEMPERATURES

Abstract: A double-stage split-sphere apparatus has been developed for a series of phase-transformation studies at high pressures up to about 300kb and at high tempepatures of around 1000°C. First, the coesite-stishovite transition curve has been determined to calibrate the pressures at high temperatures. Then the olivine-distorted spinel transition in pure Mg2SiO4 has been investigated in the temperature range from 700 to 1200°C and at pressures above 100kb. The spinel phase of pure Mg2SiO4 has been finally synthesized at 1000°C at pressures higher than 220kb. Mg-rich spinels in the system Fe2SiO4-Mg2SiO4 have also been synthesized in order to complete the phase diagram at 1000°C.

Structural genes of ATP-dependent deoxyribonuclease of Escherichia coli.

Abstract: RECOMBINATION-deficient (Rec−) mutants of E. coli express pleiotropic alterations of various phenotypes such as increased ultraviolet light sensitivity, altered patterns of DNA degradation after irradiation, inability to support growth of certain λ phage mutants and many others in addition to reduced recipient ability in mating with Hfr bacteria1. Yet the primary function of any one of the genes responsible for these alterations has not been elucidated. In this paper, the characteristics of recB and recC mutants having temperature-sensitive functions are described. Particular attention is paid to the properties of the ATP-dependent deoxyribonuclease which is known to be missing in recB and recC mutants2–5.

Heat Capacity of [Cr4(OH)6(en)6](SO4)3·10H2O from 1.4 to 200 K and Spin Interaction

Abstract: The heat capacity was measured between 1.4 and 200 K. The magnetic contribution was determined by subtracting the lattice contribution from the overall heat capacity with the aid of effective frequency distribution function. The magnetic heat capacity showed two peaks at 2.3 K and at about 20 K. These features are satisfactorily accounted for by assuming a spin Hamiltonian of the form, \(\mathscr{H}{=}-J(\textbf{\itshape S}_{1}{\cdot}\textbf{\itshape S}_{3})-j[(\textbf{\itshape S}_{1}{\cdot}\textbf{\itshape S}_{2})+(\textbf{\itshape S}_{2}{\cdot}\textbf{\itshape S}_{3})+(\textbf{\itshape S}_{3}{\cdot}\textbf{\itshape S}_{4})+(\textbf{\itshape S}_{4}{\cdot}\textbf{\itshape S}_{1})]-J_{24}(\textbf{\itshape S}_{2}{\cdot}\textbf{\itshape S}_{4})\). The closest agreement between theory and experiment was obtained for J =-42.6 k , j =-22.8 k and J 24 =-7.6 k . The sign of the parameters indicates that all the spin interactions are antiferromagnetic. It was concluded that one need not introduce any higher-order ...