4,162 research outputs found

    Existence of Multistring Solutions of the Self-Gravitating Massive W−W-Boson

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    We consider a semilinear elliptic system which include the model system of the W−W-strings in the cosmology as a special case. We prove existence of multi-string solutions and obtain precise asymptotic decay estimates near infinity for the solutions. As a special case of this result we solve an open problem posed in \cite{yan}Comment: 12 page

    Epitaxial growth and the magnetic properties of orthorhombic YTiO3 thin films

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    High-quality YTiO3 thin films were grown on LaAlO3 (110) substrates at low oxygen pressures (<10-8 Torr) using pulsed laser deposition. The in-plane asymmetric atomic arrangements at the substrate surface allowed us to grow epitaxial YTiO3 thin films, which have an orthorhombic crystal structure with quite different a- and b-axes lattice constants. The YTiO3 film exhibited a clear ferromagnetic transition at 30 K with a saturation magnetization of about 0.7 uB/Ti. The magnetic easy axis was found to be along the [1-10] direction of the substrate, which differs from the single crystal easy axis direction, i.e., [001].Comment: 14 pages, 4 figure

    Determination of Dynamic Shear Modulus of Soils from Static Strength

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    A correlation study between the dynamic shear modulus obtained from the resonant column technique and the static strength obtained from the undrained triaxial compression test is described. The materials studied were a uniform sand, a non-active fine silty clay and a highly-active bentonite clay treated with additives to increase the range for static and dynamic shear strength of the soils. It is noted that a linear relationship exists between the dynamic shear modulus, except for those soil specimens having very low strength, independent of test parameters. Using linear regression analysis, empirical equations for predicting the maximum dynamic shear modulus from the static strength have been obtained for the three different soils

    Direct observation of the proliferation of ferroelectric loop domains and vortex-antivortex pairs

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    We discovered "stripe" patterns of trimerization-ferroelectric domains in hexagonal REMnO3 (RE=Ho, ---, Lu) crystals (grown below ferroelectric transition temperatures (Tc), reaching up to 1435 oC), in contrast with the vortex patterns in YMnO3. These stripe patterns roughen with the appearance of numerous loop domains through thermal annealing just below Tc, but the stripe domain patterns turn to vortex-antivortex domain patterns through a freezing process when crystals cross Tc even though the phase transition appears not to be Kosterlitz-Thouless-type. The experimental systematics are compared with the results of our six-state clock model simulation and also the Kibble-Zurek Mechanism for trapped topological defects

    Global classical solutions for partially dissipative hyperbolic system of balance laws

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    This work is concerned with (NN-component) hyperbolic system of balance laws in arbitrary space dimensions. Under entropy dissipative assumption and the Shizuta-Kawashima algebraic condition, a general theory on the well-posedness of classical solutions in the framework of Chemin-Lerner's spaces with critical regularity is established. To do this, we first explore the functional space theory and develop an elementary fact that indicates the relation between homogeneous and inhomogeneous Chemin-Lerner's spaces. Then this fact allows to prove the local well-posedness for general data and global well-posedness for small data by using the Fourier frequency-localization argument. Finally, we apply the new existence theory to a specific fluid model-the compressible Euler equations with damping, and obtain the corresponding results in critical spaces.Comment: 39 page

    Asymmetry in fatigue and recovery in ferroelectric Pb(Zr,Ti)O3 thin-film capacitors

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    We investigate the fatigue and refreshment by dc-electrical field of the electrical properties of Pt/Pb(Ti,Zr)O3_3/Pt ferroelectric capacitors. We find an asymmetry in the refreshment, that is, the fatigued state can be refreshed by application of negative high dc-voltage to the top electrode, but no refreshment is measured by positive dc-voltage application. We also find that the fatigue can be prevented by driving the capacitor asymmetrically.Comment: 4 pages, 5 figure
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