Permitting Sale of Insurance By Bank Holding Company Subsidiaries: A Revised Analytic Framework

The authors examine the history of the Bank Holding Company Act and the 1970 Amendments, particularly as they relate to the authorized nonbanking activity of insurance sales. After discussing present Federal Reserve Board attitudes toward bank holding company applications to engage in insurance activities, the authors identify inherent weakness in the Board\u27s current policies and suggest a revised framework for analysis of such application

Permitting Sale of Insurance By Bank Holding Company Subsidiaries: A Revised Analytic Framework

The authors examine the history of the Bank Holding Company Act and the 1970 Amendments, particularly as they relate to the authorized nonbanking activity of insurance sales. After discussing present Federal Reserve Board attitudes toward bank holding company applications to engage in insurance activities, the authors identify inherent weakness in the Board\u27s current policies and suggest a revised framework for analysis of such application

Application of ERTS-A data to agricultural practices in the Mississippi Delta region

There are no author-identified significant results in this report

Two regimes for effects of surface disorder on the zero-bias conductance peak of tunnel junctions involving d-wave superconductors

Impurity-induced quasiparticle bound states on a pair-breaking surface of a d-wave superconductor are theoretically described, taking into account hybridization of impurity- and surface-induced Andreev states. Further a theory for effects of surface disorder (of thin impurity surface layer) on the low-bias conductance of tunnel junctions is developed. We find a threshold $n_c$ for surface impurity concentration $n_S$, which separates the two regimes for surface impurity effects on the zero-bias conductance peak (ZBCP). Below the threshold, surface impurities do not broaden the ZBCP, but effectively reduce its weight and generate impurity bands. For low $n_S$ impurity bands can be, in principle, resolved experimentally, being centered at energies of bound states induced by an isolated impurity on the surface. For larger $n_S$ impurity bands are distorted, move to lower energies and, beginning with the threshold concentration $n_S=n_c$, become centered at zero energy. With increasing $n_S$ above the threshold, the ZBCP is quickly destroyed in the case of strong scatterers, while it is gradually suppressed and broaden in the presence of weak impurity potentials. More realistic cases, taking into account additional broadening, not related to the surface disorder, are also considered.Comment: 9 pages, 7 figure

On the effect of far impurities on the density of states of two-dimensional electron gas in a strong magnetic field

The effect of impurities situated at different distances from a two-dimensional electron gas on the density of states in a strong magnetic field is analyzed. Based on the exact result of Brezin, Gross, and Itzykson, we calculate the density of states in the whole energy range, assuming the Poisson distribution of impurities in the bulk. It is shown that in the case of small impurity concentration the density of states is qualitatively different from the model case when all impurities are located in the plane of the two-dimensional electron gas.Comment: 6 pages, 1 figure, submitted to JETP Letter

Quasiclassical negative magnetoresistance of a 2D electron gas: interplay of strong scatterers and smooth disorder

We study the quasiclassical magnetotransport of non-interacting fermions in two dimensions moving in a random array of strong scatterers (antidots, impurities or defects) on the background of a smooth random potential. We demonstrate that the combination of the two types of disorder induces a novel mechanism leading to a strong negative magnetoresistance, followed by the saturation of the magnetoresistivity $\rho_{xx}(B)$ at a value determined solely by the smooth disorder. Experimental relevance to the transport in semiconductor heterostructures is discussed.Comment: 4 pages, 2 figure

Photocurrent in nanostructures with asymmetric antidots

The steady current induced by electromagnetic field in a 2D system with asymmetric scatterers is studied. The scatterers are assumed to be oriented cuts with one diffusive and another specular sides. Besides, the existence of isotropic impurity scatterers is assumed. This simple model simulates the lattice of half-disk which have been studied numerically recently. The model allows the exact solution in the framework of the kinetic equation. The static current response in the second order of electric field is obtained. The photogalvanic tensor contains both responses to linear and circular polarization of electromagnetic field. The model possesses non-analyticity with regards to the rate of impurity scattering.Comment: 9 pages, 6 figure

Quasiclassical magnetotransport in a random array of antidots

We study theoretically the magnetoresistance $\rho_{xx}(B)$ of a two-dimensional electron gas scattered by a random ensemble of impenetrable discs in the presence of a long-range correlated random potential. We believe that this model describes a high-mobility semiconductor heterostructure with a random array of antidots. We show that the interplay of scattering by the two types of disorder generates new behavior of $\rho_{xx}(B)$ which is absent for only one kind of disorder. We demonstrate that even a weak long-range disorder becomes important with increasing $B$. In particular, although $\rho_{xx}(B)$ vanishes in the limit of large $B$ when only one type of disorder is present, we show that it keeps growing with increasing $B$ in the antidot array in the presence of smooth disorder. The reversal of the behavior of $\rho_{xx}(B)$ is due to a mutual destruction of the quasiclassical localization induced by a strong magnetic field: specifically, the adiabatic localization in the long-range Gaussian disorder is washed out by the scattering on hard discs, whereas the adiabatic drift and related percolation of cyclotron orbits destroys the localization in the dilute system of hard discs. For intermediate magnetic fields in a dilute antidot array, we show the existence of a strong negative magnetoresistance, which leads to a nonmonotonic dependence of $\rho_{xx}(B)$.Comment: 21 pages, 13 figure