1,174 research outputs found

    Investigation of environmental change pattern in Japan

    Get PDF
    The author has identified the following significant results. A detailed land use classification for a large urban area of Tokyo was made using MSS digital data. It was found that residential, commercial, industrial, and wooded areas and grasslands can be successfully classified. A mesoscale vortex associated with large ocean current, Kuroshio, which is a rare phenomenon, was recognized visually through the analysis of MSS data. It was found that this vortex affects the effluent patterns of rivers. Lava flowing from Sakurajima Volcano was clearly classified for three major erruptions (1779, 1914, and 1946) using MSS data

    Hurwitz spaces of quadruple coverings of elliptic curves and the moduli space of abelian threefolds A_3(1,1,4)

    Full text link
    We prove that the moduli space A_3(1,1,4) of polarized abelian threefolds with polarization of type (1,1,4) is unirational. By a result of Birkenhake and Lange this implies the unirationality of the isomorphic moduli space A_3(1,4,4). The result is based on the study the Hurwitz space H_{4,n}(Y) of quadruple coverings of an elliptic curve Y simply branched in n points. We prove the unirationality of its codimension one subvariety H^{0}_{4,A}(Y) which parametrizes quadruple coverings \pi:X --> Y with Tschirnhausen modules isomorphic to A^{-1}, where A\in Pic^{n/2}Y, and for which \pi^*:J(Y)--> J(X) is injective. This is an analog of the result of Arbarello and Cornalba that the Hurwitz space H_{4,n}(P^1) is unirational.Comment: 28 pages, amslatex, to appear in Mathematische Nachrichte

    Searching for hexagonal analogues of the half-metallic half-Heusler XYZ compounds

    Full text link
    The XYZ half-Heusler crystal structure can conveniently be described as a tetrahedral zinc blende YZ structure which is stuffed by a slightly ionic X species. This description is well suited to understand the electronic structure of semiconducting 8-electron compounds such as LiAlSi (formulated Li+^+[AlSi]−^-) or semiconducting 18-electron compounds such as TiCoSb (formulated Ti4+^{4+}[CoSb]4−^{4-}). The basis for this is that [AlSi]−^- (with the same electron count as Si2_2) and [CoSb]4−^{4-} (the same electron count as GaSb), are both structurally and electronically, zinc-blende semiconductors. The electronic structure of half-metallic ferromagnets in this structure type can then be described as semiconductors with stuffing magnetic ions which have a local moment: For example, 22 electron MnNiSb can be written Mn3+^{3+}[NiSb]3−^{3-}. The tendency in the 18 electron compound for a semiconducting gap -- believed to arise from strong covalency -- is carried over in MnNiSb to a tendency for a gap in one spin direction. Here we similarly propose the systematic examination of 18-electron hexagonal compounds for semiconducting gaps; these would be the "stuffed wurtzite" analogues of the "stuffed zinc blende" half-Heusler compounds. These semiconductors could then serve as the basis for possibly new families of half-metallic compounds, attained through appropriate replacement of non-magnetic ions by magnetic ones. These semiconductors and semimetals with tunable charge carrier concentrations could also be interesting in the context of magnetoresistive and thermoelectric materials.Comment: 11 pages, 6 figures, of which 4 are colou

    On surfaces with p_g=2, q=1 and K^2=5

    Full text link
    We consider minimal surfaces of general type with pg=2p_g = 2, q=1q = 1 and K2=5K^2 = 5. We provide a stratification of the corresponding moduli space and we give some bounds for the number and the dimensions of its irreducible components.Comment: 25 pages. To appear in Rendiconti del Circolo Matematico di Palerm

    Grain Dynamics in a Two-dimensional Granular Flow

    Full text link
    We have used particle tracking methods to study the dynamics of individual balls comprising a granular flow in a small-angle two-dimensional funnel. We statistically analyze many ball trajectories to examine the mechanisms of shock propagation. In particular, we study the creation of, and interactions between, shock waves. We also investigate the role of granular temperature and draw parallels to traffic flow dynamics.Comment: 17 pages, 24 figures. To appear in Phys.Rev.E. High res./color figures etc. on http://www.nbi.dk/CATS/Granular/GrainDyn.htm

    Structure function of a damped harmonic oscillator

    Full text link
    Following the Caldeira-Leggett approach to describe dissipative quantum systems the structure function for a harmonic oscillator with Ohmic dissipation is evaluated by an analytic continuation from euclidean to real time. The analytic properties of the Fourier transform of the structure function with respect to the energy transfer (the ``characteristic function'') are studied and utilized. In the one-parameter model of Ohmic dissipation we show explicitly that the broadening of excited states increases with the state number without violating sum rules. Analytic and numerical results suggest that this is a phenomenologically relevant, consistent model to include the coupling of a single (sub-)nuclear particle to unobserved and complex degrees of freedom.Comment: 23 pages, 5 figures, RevTex4, minor changes following referee's comments and by PRC: the definite article in the original title has been droppe

    Carbon Isotopes Near Drip Lines in the Relativistic Mean-Field Theory

    Get PDF
    We have investigated the ground-state properties of carbon isotopes in the framework of the relativistic mean-field (RMF) theory. RMF calculations have been performed with the non-linear scalar self-coupling of the σ\sigma meson using an axially symmetric deformed configuration. We have also introduced the vector self-coupling of the ω\omega meson for the deformed mean-field calculations. The results show that the RMF predictions on radii and deformations are in good agreement with the available experimental data. It is shown that several carbon isotopes possess a highly deformed shape akin to a superdeformation. The single-particle structure of nuclei away from the stability line has been discussed with a view to understand the properties near the neutron drip line. Predictions of properties of carbon isotopes away from the stability line are made.Comment: Revtex, 29 pages, 11 postscript figures include

    Calpain system regulates muscle mass and glucose transporter GLUT4 turnover

    Get PDF
    The experiments in this study were undertaken to determine whether inhibition of calpain activity in skeletal muscle is associated with alterations in muscle metabolism. Transgenic mice that overexpress human calpastatin, an endogenous calpain inhibitor, in skeletal muscle were produced. Compared with wild type controls, muscle calpastatin mice demonstrated normal glucose tolerance. Levels of the glucose transporter GLUT4 were increased more than 3-fold in the transgenic mice by Western blotting while mRNA levels for GLUT4 and myocyte enhancer factors, MEF 2A and MEF 2D, protein levels were decreased. We found that GLUT4 can be degraded by calpain-2, suggesting that diminished degradation is responsible for the increase in muscle GLUT4 in the calpastatin transgenic mice. Despite the increase in GLUT4, glucose transport into isolated muscles from transgenic mice was not increased in response to insulin. The expression of protein kinase B was decreased by approximately 60% in calpastatin transgenic muscle. This decrease could play a role in accounting for the insulin resistance relative to GLUT4 content of calpastatin transgenic muscle. The muscle weights of transgenic animals were substantially increased compared with controls. These results are consistent with the conclusion that calpain-mediated pathways play an important role in the regulation of GLUT4 degradation in muscle and in the regulation of muscle mass. Inhibition of calpain activity in muscle by overexpression of calpastatin is associated with an increase in GLUT4 protein without a proportional increase in insulin-stimulated glucose transport. These findings provide evidence for a physiological role for calpains in the regulation of muscle glucose metabolism and muscle mass

    Delta degrees of freedom in antisymmetrized molecular dynamics and (p,p') reactions in the delta region

    Get PDF
    Delta degrees of freedom are introduced into antisymmetrized molecular dynamics (AMD). This is done by increasing the number of basic states in the AMD wave function, introducing a Skyrme-type delta-nucleon potential, and including NN↔NΔNN\leftrightarrow N\Delta reactions in the collision description. As a test of the delta dynamics, the extended AMD is applied to (p,p′') recations at Elab=800E_{\rm lab}=800 MeV for a 12^{12}C target. It is found that the ratio and the absolute values for delta peak and quasielastic peak (QEP) in the 12^{12}C(p,p′') reaction are reproduced for angles \Theta_{\rm lab} \agt 40^\circ, pointing to a correct treatment of the delta dynamics in the extended AMD. For forward angles the QEP is overestimated. The results of the AMD calculations are compared to one-step Monte Carlo (OSMC) calculations and a detailed analysis of multi-step and delta potential effects is given. As important side results we present a way to apply a Gallilei invariant theory for (N,N′') reactions up to Elab≈800E_{\rm lab} \approx 800 MeV which ensures approximate Lorentz invariance and we discuss how to fix the width parameter ν\nu of the single particle momentum distribution for outgoing nucleons in the AMD calculation.Comment: 28 pages, revtex, 12 figures included, figures are also available upon request as postscript files from the authors (e-mail: [email protected]), submitted to Phys. Rev.
    • …
    corecore