914 research outputs found

    Electronic properties of ternary quasicrystals in one dimension

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    The one-electron properties of a certain class of one-dimensional ternary quasicrystals are investigated. In particular, we show in detail the presence of a special kind of critical states called marginal critical states in these QCs. By the use of a real-space renormalization-group method, it is shown that the scaling properties of marginal critical states are characterized by stretched exponentials. These states are virtually localized, so that their presence may make a QC less conductive.Comment: 19 pages, 9 figures, 2 tables, uses REVTeX. (V3) Title, abstract, and introduction have been modified. To appear in Phys. Rev.

    Coherent State Path Integral for Bloch Particle

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    We construct a coherent state path integral formalism for the one-dimensional Bloch particle within the single band model. The transition amplitude between two coherent states is a sum of transition amplitudes with different winding numbers on the two-dimensional phase space which has the same topology as that of the cylinder. Appearance of the winding number is due to the periodicity of the quasi-momentum of the Bloch particle. Our formalism is successfully applied to a semiclassical motion of the Bloch particle under a uniform electric field. The wave packet exhibits not only the Bloch oscillation but also a similar breathing to the one for the squeezed state of a harmonic oscillator.Comment: 10 pages, Revtev

    Classification of one-dimensional quasilattices into mutual local-derivability classes

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    One-dimensional quasilattices are classified into mutual local-derivability (MLD) classes on the basis of geometrical and number-theoretical considerations. Most quasilattices are ternary, and there exist an infinite number of MLD classes. Every MLD class has a finite number of quasilattices with inflation symmetries. We can choose one of them as the representative of the MLD class, and other members are given as decorations of the representative. Several MLD classes of particular importance are listed. The symmetry-preserving decorations rules are investigated extensively.Comment: 42 pages, latex, 5 eps figures, Published in JPS

    Energy-Saving Technological Change in Japan

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    The energy-dependence of Japan's economy declined considerably following the first oil crisis in 1973. This paper examines what caused the sharp drop in the use of energy per unit of gross national product (GNP) observed in the 1970s and 1980s, using a simple neo-classical growth model with energy as a third production input. Two possible candidates are investigated: (i) the substitution effect due to changes in the relative price of energy, and (ii) energy-saving technological progress. The findings are as follows. First, the substitution effect alone is weak and alone cannot account for the decline in the energy-GNP ratio. Second, the estimated level of energy-saving technology more than tripled between 1970 and the late 1980s, and the model with energy-saving technological progress is able to explain the drop in the energy-GNP ratio well.Relative Energy Price, Energy-saving Technological Progress

    Universalities in One-electron Properties of Limit Quasi-periodic Lattices

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    We investigate one-electron properties of one-dimensional self-similar structures called limit quasi-periodic lattices. The trace map of such a lattice is nonconservative in contrast to the quasi-periodic case, and we can determine the structure of its attractor. It allows us to obtain the three new features of the present system: 1) The multi-fractal characters of the energy spectra are {\it universal}. 2) The supports of the f(α)f(\alpha)-spectra extend over the whole unit interval, [0,1][0, 1]. 3) There exist marginal critical states.Comment: 4 pages, 2figure

    Sound modes broadening for Fibonacci one dimensional quasicrystals

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    We investigate vibrational excitation broadening in one dimensional Fibonacci model of quasicrystals (QCs). The chain is constructed from particles with two masses following the Fibonacci inflation rule. The eigenmode spectrum depends crucially on the mass ratio. We calculate the eigenstates and eigenfunctions. All calculations performed self-consistently within the regular expansion over the three wave coupling constant. The approach can be extended to three dimensional systems. We find that in the intermediate range of mode coupling constants, three-wave broadening for the both types of systems (1D Fibonacci and 3D QCs) depends universally on frequency. Our general qualitative conclusion is that for a system with a non-simple elementary cell phonon spectrum broadening is always larger than for a system with a primitive cell (provided all other characteristics are the same).Comment: 2o pages, 15 figure

    A Substance p Agonist Acts as an Adjuvant to Promote Hapten-Specific Skin Immunity

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    Because substance p (SP) has been reported to be released from cutaneous sensory nerve endings after hapten application, we determined whether SP participates in contact hypersensitivity (CH) induction by using a SP agonist, GR73632 or ή-Aminovaleryl [Pro9, N-Me-Leu10[-substance P7–11 and a SP antagonist, spantide I. When injected intradermally, SP agonist enhanced CH induced by conventional, but not optimal, sensitizing doses of hapten. By contrast, SP antagonist inhibited the induction of CH by optimal sensitizing doses of hapten. Moreover, SP agonist promoted CH induction and prevented tolerance when hapten was painted on skin exposed to acute, low-dose ultraviolet-B radiation. Intradermally injected SP agonist altered neither the density nor the morphology of epidermal Langerhans cells, implying that SP agonist enhanced the generation of hapten-specific immunogenic signals from the dermis. It is proposed that SP is a natural “adjuvant” that promotes the induction of CH within normal skin. Although exogenous SP agonist can prevent impaired CH and tolerance after ultraviolet-B radiation, the susceptibility of native SP to local neuropeptidases renders the neuropeptide unable to prevent the deleterious effects of ultraviolet-B radiation on cutaneous immunity
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