4,358 research outputs found
Lunar response to the time-varying interplanetary magnetic field and application to the ALSEP magnetometer experiment
Mathematical model for predicting lunar response to time varying interplanetary magnetic fields and its applicability to interpretation of ALSEP magnetometer dat
Interaction of the solar wind with a planetary ionosphere
An electrodynamic model for an ionosphere-solar wind interaction is developed based on the existence of a low beta plasma below the anemopause. The currents for the interaction are driven by the solar wind motional electric field and induce a stagnation magnetic field at the anemopause. For Venus and Mars the lower region of the ionosphere near the electron density peak has the highest conductivity, and therefore the tangential component of the induction current flows substantially in this region. The current paths close in the anemopause, which is a solar wind current sheath analogous to the magnetopause. Both the fraction of the undisturbed solar wind motional electric field, which drives the induction current, and the required fraction of incident solar wind particles, crossing the anemopause to produce this current, are shown to be small
Electrostatic potential distribution of the sunlit lunar surface
Electrostatic potential distribution on sunlit lunar surfac
Method for estimating the electrical conductivity of the lunar interior
Estimation method for electrical conductivity of lunar interio
PROFIT PATTERNS IN THE U.S. AND THE WEST, 1992 AND 1997: WHAT COUNTY-LEVEL DATA REVEAL
We examine whether there are spatial relationships in U.S. production agriculture's profitability across regions and over time. We test the traditional view that factor markets (approximately) adjust to equalize agriculture's net returns over space and time using county-level data from the UDSA's Census of Agriculture, 1992 and 1997. We estimate Gini coefficients and calculate the Theil Entropy Measure (TMI) to examine changes in the concentration of returns over space and time, and to decompose the variation in inequality in returns due to between-region variation in returns. Although factor markets (approximately) adjust to equalize net returns over space and time, there is still considerable variability in returns within regions and within states. Use of county-level (Census of Agriculture) and farm-level data (ARMS Survey) to help highlight these differences. In general, farm-level Gini coefficients have remained fairly constant but show a mild increase in concentration since the 1996 FAIR Act. The TMI analysis reveals that in 1997 about 54 percent of the variation in total returns (net cash returns) was due to within-region variation, and about 46 percent was due to (average) between-region variation (compared to 53 and 47 percent in 1992). Total U.S. inequity of net cash returns increased from 0.14 in 1992 to 0.21 in 1997.Gini coefficient, Theil Entropy Measure, net cash returns, net cash and net farm income, farm structure, Agricultural Finance, Community/Rural/Urban Development, Q, Q140,
On the discovery of doubly-magic Ni
The paper reports on the first observation of doubly-magic Nickel-48 in an
experimental at the SISSI/LISE3 facility of GANIL. Four Nickel-48 isotopes were
identified. In addition, roughly 100 Nickel-49, 50 Iron-45, and 290 Chromium-42
isotopes were observed. This opens the possibility to search for two-proton
emission from these nuclei.Comment: 4 pages, 3 figures, accepted for publication in Phys. Rev. Let
Multiple conducting carriers generated in LaAlO3/SrTiO3 heterostructures
We have found that there is more than one type of conducting carriers
generated in LaAlO3/SrTiO3 heterostructures by comparing the sheet carrier
density and mobility from optical transmission spectroscopy with those from
dc-transport measurements. When multiple types of carriers exist, optical
characterization dominantly reflects the contribution from the high-density
carriers whereas dc-transport measurements may exaggerate the contribution of
the high-mobility carriers even though they are present at low-density. Since
the low-temperature mobilities determined by dc-transport in the LaAlO3/SrTiO3
heterostructures are much higher than those extracted by optical method, we
attribute the origin of high-mobility transport to the low-density conducting
carriers.Comment: 3 figures, supplemental materia
Proton drip-line nuclei in Relativistic Hartree-Bogoliubov theory
Ground-state properties of spherical even-even nuclei and
are described in the framework of Relativistic Hartree Bogoliubov
(RHB) theory. The model uses the NL3 effective interaction in the mean-field
Lagrangian, and describes pairing correlations by the pairing part of the
finite range Gogny interaction D1S. Binding energies, two-proton separation
energies, and proton radii that result from fully self-consistent RHB
solutions are compared with experimental data. The model predicts the location
of the proton drip-line. The isospin dependence of the effective spin-orbit
potential is discussed, as well as pairing properties that result from the
finite range interaction in the channel.Comment: 12 pages, RevTex, 10 p.s figures, submitted to Phys. Rev.
Parallel electron-hole bilayer conductivity from electronic interface reconstruction
The perovskite SrTiO-LaAlO structure has advanced to a model system
to investigate the rich electronic phenomena arising at polar interfaces. Using
first principles calculations and transport measurements we demonstrate that an
additional SrTiO capping layer prevents structural and chemical
reconstruction at the LaAlO surface and triggers the electronic
reconstruction at a significantly lower LaAlO film thickness than for the
uncapped systems. Combined theoretical and experimental evidence (from
magnetotransport and ultraviolet photoelectron spectroscopy) suggests two
spatially separated sheets with electron and hole carriers, that are as close
as 1 nm.Comment: Phys. Rev. Lett., in pres
Two-Dimensional Confinement of 3d1 Electrons in LaTiO3/LaAlO3 Multilayers
We report spectroscopic ellipsometry measurements of the anisotropy of the
interband transitions parallel and perpendicular to the planes of
(LaTiO3)n(LaAlO3)5 multilayers with n = 1-3. These provide direct information
about the electronic structure of the two-dimensional (2D) 3d^1 state of the Ti
ions. In combination with LDA+U calculations, we suggest that 2D confinement in
the TiO2 slabs lifts the degeneracy of the t_{2g} states leaving only the
planar d_xy orbitals occupied. We outline that these multilayers can serve as a
model system for the study of the t_{2g} 2D Hubbard model.Comment: 7 pages, 4 figures. Accepted for publication in Phys. Rev. Let
- …