576 research outputs found

    Comparison of topologies on *-algebras of locally measurable operators

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    We consider the locally measure topology t(M)t(\mathcal{M}) on the *-algebra LS(M)LS(\mathcal{M}) of all locally measurable operators affiliated with a von Neumann algebra M\mathcal{M}. We prove that t(M)t(\mathcal{M}) coincides with the (o)(o)-topology on LSh(M)={T∈LS(M):T∗=T}LS_h(\mathcal{M})=\{T\in LS(\mathcal{M}): T^*=T\} if and only if the algebra M\mathcal{M} is σ\sigma-finite and a finite algebra. We study relationships between the topology t(M)t(\mathcal{M}) and various topologies generated by faithful normal semifinite traces on M\mathcal{M}.Comment: 21 page

    Front propagation in geometric and phase field models of stratified media

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    We study front propagation problems for forced mean curvature flows and their phase field variants that take place in stratified media, i.e., heterogeneous media whose characteristics do not vary in one direction. We consider phase change fronts in infinite cylinders whose axis coincides with the symmetry axis of the medium. Using the recently developed variational approaches, we provide a convergence result relating asymptotic in time front propagation in the diffuse interface case to that in the sharp interface case, for suitably balanced nonlinearities of Allen-Cahn type. The result is established by using arguments in the spirit of Γ\Gamma-convergence, to obtain a correspondence between the minimizers of an exponentially weighted Ginzburg-Landau type functional and the minimizers of an exponentially weighted area type functional. These minimizers yield the fastest traveling waves invading a given stable equilibrium in the respective models and determine the asymptotic propagation speeds for front-like initial data. We further show that generically these fronts are the exponentially stable global attractors for this kind of initial data and give sufficient conditions under which complete phase change occurs via the formation of the considered fronts

    Walker solution for Dzyaloshinskii domain wall in ultrathin ferromagnetic films

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    We analyze the electric current and magnetic field driven domain wall motion in perpendicularly magnetized ultrathin ferromagnetic films in the presence of interfacial Dzyaloshinskii-Moriya interaction and both out-of-plane and in-plane uniaxial anisotropies. We obtain exact analytical Walker-type solutions in the form of one-dimensional domain walls moving with constant velocity due to both spin-transfer torques and out-of-plane magnetic field. These solutions are embedded into a larger family of propagating solutions found numerically. Within the considered model, we find the dependencies of the domain wall velocity on the material parameters and demonstrate that adding in-plane anisotropy may produce domain walls moving with velocities in excess of 500 m/s in realistic materials under moderate fields and currents.Comment: 6 pages, 2 figure

    Instabilities and disorder of the domain patterns in the systems with competing interactions

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    The dynamics of the domains is studied in a two-dimensional model of the microphase separation of diblock copolymers in the vicinity of the transition. A criterion for the validity of the mean field theory is derived. It is shown that at certain temperatures the ordered hexagonal pattern becomes unstable with respect to the two types of instabilities: the radially-nonsymmetric distortions of the domains and the repumping of the order parameter between the neighbors. Both these instabilities may lead to the transformation of the regular hexagonal pattern into a disordered pattern.Comment: ReVTeX, 4 pages, 3 figures (postscript); submitted to Phys. Rev. Let

    Practical formula for the shear viscosity of Yukawa fluids

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    A simple practical formula for the shear viscosity coefficient of Yukawa fluids is presented. This formula allows estimation of the shear viscosity in a very extended range of temperatures, from the melting point to ≃100\simeq 100 times the melting temperature. It demonstrates reasonable agreement with the available results from molecular dynamics simulations. Some aspects of the temperature dependence of the shear viscosity and diffusion coefficients on approaching the fluid-solid phase transition are discussed.Comment: 7 pages with 3 figure and 1 tabl

    Translation of Muratov, E. A. 1966. Kroveparazit roda \u3ci\u3eNuttallia\u3c/i\u3e Franca ot domovoi myshi (\u3ci\u3eMus musculus\u3c/i\u3e Lin.) [= A blood parasite of the genus \u3ci\u3eNuttallia\u3c/i\u3e from the house mouse, \u3ci\u3eMus musculus\u3c/i\u3e]. \u3ci\u3eDokl. Tadzhik SSR\u3c/i\u3e 9(5): 34-47

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    Translation number 27, College of Veterinary Medicine, University of Illinois, Urbana, Illinois, United States (4 pages) Translation of Muratov, E. A. 1966. Kroveparazit roda Nuttallia Franca ot domovoi myshi (Mus musculus Lin.) [= A blood parasite of the genus Nuttallia from the house mouse, Mus musculus]. Dokl. Tadzhik SSR 9(5): 34-47 Translated from Russian to English by Frederick K. Plous, Jr., and edited by Norman D. Levin
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