41,053 research outputs found
First principle electronic, structural, elastic, and optical properties of strontium titanate
We report self-consistent ab-initio electronic, structural, elastic, and
optical properties of cubic SrTiO perovskite. Our non-relativistic
calculations employed a generalized gradient approximation (GGA) potential and
the linear combination of atomic orbitals (LCAO) formalism. The distinctive
feature of our computations stem from solving self-consistently the system of
equations describing the GGA, using the Bagayoko-Zhao-Williams (BZW) method.
Our results are in agreement with experimental ones where the later are
available. In particular, our theoretical, indirect band gap of 3.24 eV, at the
experimental lattice constant of 3.91 \AA{}, is in excellent agreement with
experiment. Our predicted, equilibrium lattice constant is 3.92 \AA{}, with a
corresponding indirect band gap of 3.21 eV and bulk modulus of 183 GPa.Comment: 11 pages, 6 figures,Accepted for publication in AIP Advances (2012
Dying with Dignity : Is This a Universal Concept?
Peer reviewedPublisher PD
Errors on the inverse problem solution for a noisy spherical gravitational wave antenna
A single spherical antenna is capable of measuring the direction and
polarization of a gravitational wave. It is possible to solve the inverse
problem using only linear algebra even in the presence of noise. The simplicity
of this solution enables one to explore the error on the solution using
standard techniques. In this paper we derive the error on the direction and
polarization measurements of a gravitational wave. We show that the solid angle
error and the uncertainty on the wave amplitude are direction independent. We
also discuss the possibility of determining the polarization amplitudes with
isotropic sensitivity for any given gravitational wave source.Comment: 13 pages, 4 figures, LaTeX2e, IOP style, submitted to CQ
Deceleration of the solar wind in the Earth foreshock region: ISEE 2 and IMP 8 observations
The deceleration of the solar wind in the region of the interplanetary space filled by ions backstreaming from the Earth bow shock was studied using a two spacecraft technique. This deceleration, which is correlated with the "diffuse" but not with the "reflected" ion population, depends on the solar wind bulk velocity: at low velocities (below 300 km/sec) the velocity decrease is about 5 km/sec, while at higher velocities (above 400 km/sec) the decrease may be as large as 30 km/sec. Along with this deceleration, the solar wind undergoes a deflection of about 1 deg away from the direction of the Earth bow shock. The energy balance shows that the kinetic energy loss far exceeds the thermal energy which is possibly gained by the solar wind, therefore, at least part of this energy must go into waves and/or into the backstreaming ions
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