Calculation of the optical conductivity for the Anderson impurity model using the slave boson technique

The optical conductivity of the Anderson impurity mode l has been calculated by emp l oying the slave boson technique and an expansion in powers of l i N, where N is the d egeneracy o f the f electron level . This method has been used to find the effective mass of the conduction electrons for temperatures above and below the Kondo tempera ture. For low temperatures, the mass enhancement is f ound to be large while a t high t emperatures, the mass enhancement is sma ll. The conductivity i s f ound to be Drude like with frequency dependent effective mass and scattering time for low independent effective mass and temperatures and scattering time f requency for high t emperatures. The behavior of both the effective mass and the conductivity is in qualitative agreement with experimental r esul t s .

The slave in Upper Canada (1919)

Inscribed on cover: Falconbridge 1919. Previous owner's name inscribed on front flyleaf and stamped on various pages. "Reprinted from the Journal of Negro History, vol. iv, no.4, October, 1919" - cover.

Slave-boson approach to the size-dependent transition from van der Waals to covalent bonding in Hg_n clusters

We use a microscopic theory to describe the dynamics of the valence electrons in divalent-metal clusters. The theory is based on a many-body model Harniltonian H which takes into account, on the same electronic level, the van der Waals and the covalent bonding. In order to study the ground-state properties of H we have developed an extended slave-boson method. We have studied the bonding character and the degree of electronic delocalization in Hg_n clusters as a function of cluster size. Results show that, for increasing cluster size, an abrupt change occurs in the bond character from van der Waals to covalent bonding at a critical cluster size n_c ~ 10-20. This change also involves a transition from localized to delocalized valence electrons, as a consequence of the competition between both bonding mechanisms.

An LMI approach to H∞ synchronization of second-order neutral master-slave systems

The H∞ synchronization problem of the master and slave structure of a second-order neutral master-slave systems with time-varying delays is presented in this paper. Delay-dependent sufficient conditions for the design of a delayed output-feedback control are given by Lyapunov-Krasovskii method in terms of a linear matrix inequality (LMI). A controller, which guarantees H∞ synchronization of the master and slave structure using some free weighting matrices, is then developed. A numerical example has been given to show the effectiveness of the method

The slave trade : should Britain pay compensation for the slave trade?

Estudia el comercio de esclavos, a través de barcos británicos, entre África y América en el siglo XVIII y el movimiento abolicionista como uno de los primeros movimientos modernos de protesta.Para ello utiliza los relatos de primera mano de personajes de la serie de televisión Raíces y fuentes históricas. Se adapta a la etapa clave 3 (key stage 3) de secundaria para historia del programa nacional de estudios.

The slave trade : 1440 to 1770.

Forma parte de una serie que estudia la historia del hombre negro y de sus logros en el contexto histórico mundial. Este texto explica el estado de las culturas africanas hacia 1400 cuando llegan comerciantes europeos al oeste del continente; el comienzo del mercado de esclavos desde África hasta América; la colonización británica; la empresa internacional del comercio de esclavos desde 1600 hasta 1800; los movimientos de protesta y resistencia y la construcción de nuevas vidas en América.