18,803 research outputs found
The effects of restraint on uptake of radioactive sulfate in the salivary and gastric secretions of rats with pyloric ligation
The effects of restraint on the amount of nondialysable radioactive sulfate in the gastric wall and the gastric juice and saliva were investigated. It was found that restraint provokes a significant decrease in salivary radioactive sulfate. This, in turn, is responsible for the decrease of sulfate in the gastric contents observed under these conditions in rats with pyloric ligation. Esophageal ligation associated with this prevents passage of saliva and lowers the amount of radioactive sulfate in the gastric juice. Restraint causes then an increase in the amount of sulfate in the gastric juice, the value observed being very much lower than that of rats with a free esophagus. At the level of the gastric wall, the change observed during restraint does not reach a significant threshold
One step multiderivative methods for first order ordinary differential equations
A family of one-step multiderivative methods based on Padé approximants to the exponential function is developed.
The methods are extrapolated and analysed for use in PECE mode.
Error constants and stability intervals are calculated and the combinations compared with well known linear multi-step combinations and combinations using high accuracy Newton-Cotes quadrature formulas as correctors.
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Investigation of tidal displacements of the Earth's surface by laser ranging to GEOS-3
An analysis of laser ranging data from three stations was carried out in an attempt to measure the geometric Earth tide. Two different approaches to the problem were investigated. The dynamic method computes pass to pass apparent movements in stations height relative to short arcs fitted to several passes of data from the same station by the program GEODYNE. The quasi-geometric method reduces the dependence on unmodelled satellite dynamics to a knowledge of only the radial position of the satellite by considering two station simultaneous ranging at the precise time that the satellite passes through the plane defined by two stations and the center of mass of the Earth
Suppression of Giant Magnetoresistance by a superconducting contact
We predict that current perpendicular to the plane (CPP) giant
magnetoresistance (GMR) in a phase-coherent magnetic multilayer is suppressed
when one of the contacts is superconducting. This is a consequence of a
superconductivity-induced magneto-resistive (SMR) effect, whereby the
conductance of the ferromagnetically aligned state is drastically reduced by
superconductivity. To demonstrate this effect, we compute the GMR ratio of
clean (Cu/Co)_nCu and (Cu/Co)_nPb multilayers, described by an ab-initio spd
tight binding Hamiltonian. By analyzing a simpler model with two orbitals per
site, we also show that the suppression survives in the presence of elastic
scattering by impurities.Comment: 5 pages, 4 figures. Submitted to PR
Giant Backscattering Peak in Angle-Resolved Andreev Reflection
It is shown analytically and by numerical simulation that the angular
distribution of Andreev reflection by a disordered normal-metal --
superconductor junction has a narrow peak at the angle of incidence. The peak
is higher than the well-known coherent backscattering peak in the normal state,
by a large factor G/G_0 (where G is the conductance of the junction and
G_0=2e^2/h). The enhanced backscattering can be detected by means of ballistic
point contacts.Comment: Instituut-Lorentz, Leiden, The Netherlands, 4 pages, REVTeX-3.0, 3
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Phase coherent transport in hybrid superconducting structures: the case of d-wave superconductors
We examine the effect of d-wave symmetry on zero bias anomalies in
normal-superconducting tunnel junctions and phase-periodic conductances in
Andreev interferometers. In the presence of d-wave pairing, zero-bias anomalies
are suppressed compared with the s-wave case. For Andreev interferometers with
aligned islands, the phase-periodic conductance is insensistive to the nature
of the pairing, whereas for non-aligned islands, the nature of the zero-phase
extremum is reversed.Comment: 10 Pages, Revtex. 11 postscript figures available on reques
Solar cell research, phase 2 Semiannual report
Radiation effects on properties of lithium solar cell
Ultraviolet spectroscopy of old novae and symbiotic stars
The IUE spectra are presented for two old novae and for two of the symbiotic variables. Prominent emission line spectra are revealed as a continuum whose appearance is effected by the system inclination. These data provide evidence for hot companions in the symbiotic stars, making plausible the binary model for these peculiar stars. Recent IUE spectra of dwarf novae provide additional support for the existence of optically thick accretion disks in active binary systems. The ultraviolet data of the eclipsing dwarf novae EX Hya and BV Cen appear flatter than for the noneclipsing systems, an effect which could be ascribed to the system inclination
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