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991.
We study the Kondo screening of a single magnetic impurity inside a nonmagnetic quantum corral located on the surface of a metallic host system. We show that the spatial structure of the corral's eigenmodes leads to a spatially dependent Kondo effect whose signatures are spatial variations of the Kondo temperature T K. Moreover, we predict that the Kondo screening is accompanied by the formation of multiple Kondo resonances with characteristic spatial patterns. Our results open new possibilities to manipulate and explore the Kondo effect by using quantum corrals. 相似文献
992.
A rigorous ab initio derivation of the (square of) Dirac’s equation for a particle with spin is presented. The Lagrangian of the classical relativistic spherical top is modified so to render it invariant with respect conformal changes of the metric of the top configuration space. The conformal invariance is achieved by replacing the particle mass in the Lagrangian with the conformal Weyl scalar curvature. The Hamilton-Jacobi equation for the particle is found to be linearized, exactly and in closed form, by an ansatz solution that can be straightforwardly interpreted as the “quantum wave function” of the 4-spinor solution of Dirac’s equation. All quantum features arise from the subtle interplay between the conformal curvature acting on the particle as a potential and the particle motion which affects the geometric “pre-potential” associated to the conformal curvature itself. The theory, carried out here by assuming a Minkowski metric, can be easily extended to arbitrary space-time Riemann metric, e.g. the one adopted in the context of General Relativity. This novel theoretical scenario appears to be of general application and is expected to open a promising perspective in the modern endeavor aimed at the unification of the natural forces with gravitation. 相似文献
993.
994.
995.
We study the time reversal properties of time series by means of a ternary coding of the differentiated series. For the symbolic series obtained in this way we show that suitable pairs of ternary words have the same probability if the time series is reversible. This provides tests in which time reversibility is rejected if the estimated probabilities are significantly different. We apply one of these tests to the human heartbeat series extracted from 24 h Holter recordings of 19 healthy subjects. Data analysis shows a highly significant prevalence of irreversibility. Our symbolic approach to time reversal gives further support to the suitability of non-linear modeling of the normal heartbeat. 相似文献
996.
We consider the Neumann problem for the Hénon equation. We obtain existence results and we analyze the symmetry properties of the ground state solutions. We prove that some symmetry and variational properties can be expressed in terms of eigenvalues of a Steklov problem. Applications are also given to extremals of certain trace inequalities. 相似文献
997.
998.
Enrico M. Vitale 《Journal of Pure and Applied Algebra》2003,177(3):303-308
The categorical structure of H2 is shown to be a particular instance of the cokernel of a morphism between symmetric categorical groups. 相似文献
999.
Enrico Angeletti Roberto Baima Carlo Canepa Iacopo Degani Glauco Tonachini Paolo Venturello 《Tetrahedron》1989,45(24):7827-7834
Substituted benzaldehydes and acetophenone preferentially attack the γ position of gem-dichloro allyl anion, but show a significantly increased -selectivity if 12-crown-4 is present. This behaviour is discussed on the basis of theoretical computations. 相似文献
1000.