21,174 research outputs found
Classifying vortices in S= 3 Bose-Einstein condensates
Motivated by the recent realization of a Cr Bose-Einstein condensate,
we consider the phase diagram of a general spin-three condensate as a function
of its scattering lengths. We classify each phase according to its ``reciprocal
spinor,'' using a method developed in a previous work. We show that such a
classification can be naturally extended to describe the vortices for a spinor
condensate by using the topological theory of defects. To illustrate, we
systematically describe the types of vortex excitations for each phase of the
spin-three condensate
Temperature dependence of the average electron-hole pair creation energy in Al0.8Ga0.2As
The temperature dependence of the average energy consumed in the creation of an electron-hole pair in the wide bandgap compound semiconductor Al 0.8Ga0.2As is reported following X-ray measurements made using an Al0.8Ga0.2As photodiode diode coupled to a low-noise charge-sensitive preamplifier operating in spectroscopic photon counting mode. The temperature dependence is reported over the range of 261 K-342 K and is found to be best represented by the equation ε AlGaAs 7.327-0.0077 T, where εAlGaAs is the average electron-hole pair creation energy in eV and T is the temperature in K. © 2013 © 2013 Author(s)
Inside the Economist's Mind: The History of Modern Economic Thought, as Explained by Those Who Produced It
This is the front matter from a book of interviews to be published by Blackwell. The book is coedited by W. A. Barnett and P. A. Samuelson. The front matter includes the Table of Contents, Coeditor Preface by W. A. Barnett, Coeditor Foreword by Paul A. Samuelson, and History of Thought Introduction by E. Roy Weintraub. The front matter highlights some of the more startling and controversial statements contained in the interviews and puts the interviews into context relative to the history of modern economic thought. The interviews reprinted in this book include: (1) Wassily Leontief interviewed by Duncan Foley. (2) David Cass interviewed jointly by Steven Spear and Randall Wright. (3) Robert E. Lucas interviewed by Bennett T. McCallum. (4) Janos Kornai interviewed by Olivier Blanchard. (5) Franco Modigliani interviewed by William Barnett and Robert Solow. (6) Milton Friedman interviewed by John Taylor. (7) Paul A. Samuelson interviewed by William A. Barnett. (8) Paul Volcker interviewed by Perry Mehrling. (9) Martin Feldstein interviewed by James Poterba. (10) Christopher Sims interviewed by Lars Peter Hansen. (11) Robert Shiller interviewed by John Campbell. (12) Stanley Fischer interviewed by Olivier Blanchard. (13) Jacques Drèze interviewed by Pierre Dehez and Omar Licandro. (14) Tom Sargent interviewed by George Evans and Seppo Honkapohja. (15) Robert Aumann interviewed by Sergiu Hart. (16) James Tobin and Robert Shiller interviewed by David Colander.history of economic thought, Samuelson, macroeconomics, microeconomics, policy, interviews
N/P GaAs concentrator solar cells with an improved grid and bushbar contact design
The major requirements for a solar cell used in space applications are high efficiency at AMO irradiance and resistance to high energy radiation. Gallium arsenide, with a band gap of 1.43 eV, is one of the most efficient sunlight to electricity converters (25%) when the the simple diode model is used to calculate efficiencies at AMO irradiance, GaAs solar cells are more radiation resistant than silicon solar cells and the N/P GaAs device has been reported to be more radiation resistant than similar P/N solar cells. This higher resistance is probably due to the fact that only 37% of the current is generated in the top N layer of the N/P cell compared to 69% in the top layer of a P/N solar cell. This top layer of the cell is most affected by radiation. It has also been theoretically calculated that the optimized N/P device will prove to have a higher efficiency than a similar P/N device. The use of a GaP window layer on a GaAs solar cell will avoid many of the inherent problems normally associated with a GaAlAs window while still proving good passivation of the GaAs surface. An optimized circular grid design for solar cell concentrators has been shown which incorporates a multi-layer metallization scheme. This multi-layer design allows for a greater current carrying capacity for a unit area of shading, which results in a better output efficiency
Predictors of pre- and post-competition affective states in male martial artists: a multilevel interactional approach
The aims of this study were to examine (a) the effects of competition-related and competition-extraneous concerns on affective states; (b) the relationships of primary and secondary appraisal with affective states and (c) the main and moderating effects of personality traits on pre- and post-competition affects. Thirty-nine male elite martial artists were assessed on 12 affective states, concerns and dimensions of primary and secondary appraisal at five random times a day across 1 week before and 3 days after a competition. On the competition day, they were assessed 1 h before and immediately after the contest. Competitive trait anxiety, neuroticism and extraversion were measured at the start of the study. The competition was the most significant and stressful event experienced in the examined period and had a pervasive influence on athletes' affective states. All examined appraisal and personality factors were somewhat associated with pre- and post-competition affective states. Competitive trait anxiety was a key moderator of the relationship between cognitive appraisal and affective states. This study supports the idea that cognitive appraisal and situational and personality factors exert main and interactive effects on athletes' pre- and post-competition affects. These factors need to be accounted for in planning of emotion regulation interventions
Frictional quantum decoherence
The dynamics associated with a measurement-based master equation for quantum
Brownian motion are investigated. A scheme for obtaining time evolution from
general initial conditions is derived. This is applied to analyze dissipation
and decoherence in the evolution of both a Gaussian and a Schr\"{o}dinger cat
initial state. Dependence on the diffusive terms present in the master equation
is discussed with reference to both the coordinate and momentum
representations.Comment: 18 pages, 7 figure
Cyclotron motion and magnetic focusing in semiconductor quantum wells with spin-orbit coupling
We investigate the ballistic motion of electrons in III-V semiconductor
quantum wells with Rashba spin-orbit coupling in a perpendicular magnetic
field. Taking into account the full quantum dynamics of the problem, we explore
the modifications of classical cyclotron orbits due to spin-orbit interaction.
As a result, for electron energies comparable with the cyclotron energy the
dynamics are particularly rich and not adequately described by semiclassical
approximations. Our study is complementary to previous semiclassical approaches
concentrating on the regime of weaker fields.Comment: 14 pages, 8 figures included, version to appear in Phys. Rev.
Atmospheric transmission computer program CP
A computer program is described which allows for calculation of the effects of carbon dioxide, water vapor, methane, ozone, carbon monoxide, and nitrous oxide on earth resources remote sensing techniques. A flow chart of the program and operating instructions are provided. Comparisons are made between the atmospheric transmission obtained from laboratory and spacecraft spectrometer data and that obtained from a computer prediction using a model atmosphere and radiosonde data. Limitations of the model atmosphere are discussed. The computer program listings, input card formats, and sample runs for both radiosonde data and laboratory data are included
First Principles Study of the Electronic and Vibrational Properties of LiNbO2
In the layered transition metal oxide LiNbO the Nb () ion is
trigonal-prismatically coordinated with O ions, with the resulting crystal
field leading to a single band system for low energy properties. A
tight-binding representation shows that intraplanar second neighbor hopping
meV dominates the first neighbor interaction ( meV). The
first and third neighbor couplings are strongly modified by oxygen
displacements of the symmetric Raman-active vibrational mode, and
electron-phonon coupling to this motion may provide the coupling mechanism for
superconductivity in Li-deficient samples (where K). We calculate all
zone-center phonon modes, identify infrared (IR) and Raman active modes, and
report LO-TO splitting of the IR modes. The Born effective charges for the
metal ions are found to have considerable anisotropy reflecting the degree to
which the ions participate in interlayer coupling and covalent bonding. Insight
into the microscopic origin of the valence band density, composed of Nb
states with some mixing of O states, is obtained from examining
Wannier functions for these bands.Comment: 12 pages, 7 figures; Updated with reviewer comments; Updated
reference
Maximum Entanglement in Squeezed Boson and Fermion States
A class of squeezed boson and fermion states is studied with particular
emphasis on the nature of entanglement. We first investigate the case of
bosons, considering two-mode squeezed states. Then we construct the fermion
version to show that such states are maximum entangled, for both bosons and
fermions. To achieve these results, we demonstrate some relations involving
squeezed boson states. The generalization to the case of fermions is made by
using Grassmann variables.Comment: 4 page
- …