1,080 research outputs found

    Estimation of hand and finger kinematics using inertial sensors

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    A new dataglove is developed and presented. Inertial sensors are placed on various hand and finger segments to estimate the hand pose

    Theory of a quodon gas. With application to precipitation kinetics in solids under irradiation

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    Rate theory of the radiation-induced precipitation in solids is modified with account of non-equilibrium fluctuations driven by the gas of lattice solitons (a.k.a. quodons) produced by irradiation. According to quantitative estimations, a steady-state density of the quodon gas under sufficiently intense irradiation can be as high as the density of phonon gas. The quodon gas may be a powerful driver of the chemical reaction rates under irradiation, the strength of which exponentially increases with irradiation flux and may be comparable with strength of the phonon gas that exponentially increases with temperature. The modified rate theory is applied to modelling of copper precipitation in FeCu binary alloys under electron irradiation. In contrast to the classical rate theory, which disagrees strongly with experimental data on all precipitation parameters, the modified rate theory describes quite well both the evolution of precipitates and the matrix concentration of copper measured by different methodsComment: V. Dubinko, R. Shapovalov, Theory of a quodon gas. With application to precipitation kinetics in solids under irradiation. (Springer International Publishing, Switzerland, 2014

    Many Body Correlation Corrections to Superconducting Pairing in Two Dimensions.

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    We demonstrate that in the strong coupling limit (the superconducting gap Δ\Delta is as large as the chemical potential μ\mu), which is relevant to the high-TcT_c superconductivity, the correlation corrections to the gap and critical temperature are about 10\% of the corresponding mean field approximation values. For the weak coupling (Δμ\Delta \ll \mu) the correlation corrections are very large: of the order of 100\% of the corresponding mean field values.Comment: LaTeX 12 page

    Charge and Orbital Ordering and Spin State Transition Driven by Structural Distortion in YBaCo_2O_5

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    We have investigated electronic structures of antiferromagnetic YBaCo_2O_5 using the local spin-density approximation (LSDA) + U method. The charge and orbital ordered insulating ground state is correctly obtained with the strong on-site Coulomb interaction. Co^{2+} and Co^{3+} ions are found to be in the high spin (HS) and intermediate spin (IS) state, respectively. It is considered that the tetragonal to orthorhombic structural transition is responsible for the ordering phenomena and the spin states of Co ions. The large contribution of the orbital moment to the total magnetic moment indicates that the spin-orbit coupling is also important in YBaCo_2O_5.Comment: 4 pages including 4 figures, Submitted to Phys. Rev. Let

    Statistical Outliers and Dragon-Kings as Bose-Condensed Droplets

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    A theory of exceptional extreme events, characterized by their abnormal sizes compared with the rest of the distribution, is presented. Such outliers, called "dragon-kings", have been reported in the distribution of financial drawdowns, city-size distributions (e.g., Paris in France and London in the UK), in material failure, epileptic seizure intensities, and other systems. Within our theory, the large outliers are interpreted as droplets of Bose-Einstein condensate: the appearance of outliers is a natural consequence of the occurrence of Bose-Einstein condensation controlled by the relative degree of attraction, or utility, of the largest entities. For large populations, Zipf's law is recovered (except for the dragon-king outliers). The theory thus provides a parsimonious description of the possible coexistence of a power law distribution of event sizes (Zipf's law) and dragon-king outliers.Comment: Latex file, 16 pages, 1 figur

    Toeplitz Quantization of K\"ahler Manifolds and gl(N)gl(N) NN\to\infty

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    For general compact K\"ahler manifolds it is shown that both Toeplitz quantization and geometric quantization lead to a well-defined (by operator norm estimates) classical limit. This generalizes earlier results of the authors and Klimek and Lesniewski obtained for the torus and higher genus Riemann surfaces, respectively. We thereby arrive at an approximation of the Poisson algebra by a sequence of finite-dimensional matrix algebras gl(N)gl(N), NN\to\infty.Comment: 17 pages, AmsTeX 2.1, Sept. 93 (rev: only typos are corrected

    Atom-optics hologram in the time domain

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    The temporal evolution of an atomic wave packet interacting with object and reference electromagnetic waves is investigated beyond the weak perturbation of the initial state. It is shown that the diffraction of an ultracold atomic beam by the inhomogeneous laser field can be interpreted as if the beam passes through a three-dimensional hologram, whose thickness is proportional to the interaction time. It is found that the diffraction efficiency of such a hologram may reach 100% and is determined by the duration of laser pulses. On this basis a method for reconstruction of the object image with matter waves is offered.Comment: RevTeX, 13 pages, 8 figures; minor grammatical change

    Geodesic distance for right invariant Sobolev metrics of fractional order on the diffeomorphism group

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    We study Sobolev-type metrics of fractional order s0s\geq0 on the group \Diff_c(M) of compactly supported diffeomorphisms of a manifold MM. We show that for the important special case M=S1M=S^1 the geodesic distance on \Diff_c(S^1) vanishes if and only if s12s\leq\frac12. For other manifolds we obtain a partial characterization: the geodesic distance on \Diff_c(M) vanishes for M=R×N,s<12M=\R\times N, s<\frac12 and for M=S1×N,s12M=S^1\times N, s\leq\frac12, with NN being a compact Riemannian manifold. On the other hand the geodesic distance on \Diff_c(M) is positive for dim(M)=1,s>12\dim(M)=1, s>\frac12 and dim(M)2,s1\dim(M)\geq2, s\geq1. For M=RnM=\R^n we discuss the geodesic equations for these metrics. For n=1n=1 we obtain some well known PDEs of hydrodynamics: Burgers' equation for s=0s=0, the modified Constantin-Lax-Majda equation for s=12s=\frac 12 and the Camassa-Holm equation for s=1s=1.Comment: 16 pages. Final versio

    Large negative velocity gradients in Burgers turbulence

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    We consider 1D Burgers equation driven by large-scale white-in-time random force. The tails of the velocity gradients probability distribution function (PDF) are analyzed by saddle-point approximation in the path integral describing the velocity statistics. The structure of the saddle-point (instanton), that is velocity field configuration realizing the maximum of probability, is studied numerically in details. The numerical results allow us to find analytical solution for the long-time part of the instanton. Its careful analysis confirms the result of [Phys. Rev. Lett. 78 (8) 1452 (1997) [chao-dyn/9609005]] based on short-time estimations that the left tail of PDF has the form ln P(u_x) \propto -|u_x|^(3/2).Comment: 10 pages, RevTeX, 10 figure

    Diagonalization of the neutralino mass matrix and boson-neutralino interaction

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    We analyze a connection between neutralino mass sign, parity and structure of the neutralino-boson interaction. Correct calculation of spin-dependent and spin-independent contributions to neutralino-nuclear scattering should consider this connection. A convenient diagonalization procedure, based on the exponetial parametrization of unitary matrix, is suggested.Comment: 21 pages, RevTex
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