403 research outputs found
Characterizations of solutions for Bayesian games
Bayesian equilibria are characterized by means of consistency and one-person rationality in combination with non-emptiness or converse consistency. Moreover, strong and coalition-proof Bayesian equilibria of extended Bayesian games are introduced and it is seen that these notions can be characterized by means of consistency, one-person rationality, a version of Pareto optimality and a modification of converse consistency. It is shown that, in case of the strong Bayesian equilibrium correspondence, converse consistency can be replaced by non-emptiness. As examples we treat Bayesian potential games and Bayesian congestion games.Game Theory;Bayesian Games;game theory
Doping dependent optical properties of Bi2201
An experimental study of the in-plane optical conductivity of
(Pb,Bi)(LaSr)CuO (Bi2201) is presented
for a broad doping and temperature range. The in-plane conductivity is analyzed
within a strong coupling formalism. We address the interrelationship between
the optical conductivity (), the single particle self energy,
and the electron-boson spectral function. We find that the frequency and
temperature dependence can be well described within this formalism. We present
a universal description of optical, ARPES and tunneling spectra. The full
frequency and temperature dependence of the optical spectra and single particle
self-energy is shown to result from an electron-boson spectral function, which
shows a strong doping dependence and weak temperature dependence.Comment: 20 pages, 9 figures. To appear in special focus issue
"Superconductors with Exotic Symmetries", New Journal of Physic
Infrared phonon activity in pristine graphite
We study experimentally and theoretically the Fano-shaped phonon peak at 1590
cm (0.2 eV) in the in-plane optical conductivity of pristine graphite.
We show that the anomalously large spectral weight and the Fano asymmetry of
the peak can be qualitatively accounted for by a charged-phonon theory. A
crucial role in this context is played by the particle-hole asymmetry of the
electronic -bands.Comment: 5 pages, 4 figures, 1 tabl
Direct observation of a Fermi liquid-like normal state in an iron-pnictide superconductor
There are two prerequisites for understanding high-temperature (high-T)
superconductivity: identifying the pairing interaction and a correct
description of the normal state from which superconductivity emerges. The
nature of the normal state of iron-pnictide superconductors, and the role
played by correlations arising from partially screened interactions, are still
under debate. Here we show that the normal state of carefully annealed
electron-doped BaFeCoAs at low temperatures has all the
hallmark properties of a local Fermi liquid, with a more incoherent state
emerging at elevated temperatures, an identification made possible using
bulk-sensitive optical spectroscopy with high frequency and temperature
resolution. The frequency dependent scattering rate extracted from the optical
conductivity deviates from the expected scaling
with
1.47 rather than = 2, indicative of the presence of residual elastic
resonant scattering. Excellent agreement between the experimental results and
theoretical modeling allows us to extract the characteristic Fermi liquid scale
1700 K. Our results show that the electron-doped iron-pnictides
should be regarded as weakly correlated Fermi liquids with a weak mass
enhancement resulting from residual electron-electron scattering from thermally
excited quasi-particles.Comment: 6+9pages, 3+9 figures To be published in Scientific Report
Optical determination of the relation between the electron-boson coupling function and the critical temperature in high T cuprates
We take advantage of the connection between the free carrier optical
conductivity and the glue function in the normal state, to reconstruct from the
infrared optical conductivity the glue-spectrum of ten different high-Tc
cuprates revealing a robust peak in the 50-60 meV range and a broad con- tinuum
at higher energies for all measured charge carrier concentrations and
temperatures up to 290 K. We observe that the strong coupling formalism
accounts fully for the known strong temperature dependence of the optical
spectra of the high Tc cuprates, except for strongly underdoped samples. We
observe a correlation between the doping trend of the experimental glue spectra
and the critical temperature. The data obtained on the overdoped side of the
phase diagram conclusively excludes the electron-phonon coupling as the main
source of superconducting pairing.Comment: Accepted for publication in Phys. Rev.
Hydrodynamics of plastic deformations in electronic crystals
We construct a new hydrodynamic framework describing plastic deformations in
electronic crystals. The framework accounts for pinning, phase, and momentum
relaxation effects due to translational disorder, diffusion due to the presence
of interstitials and vacancies, and strain relaxation due to plasticity and
dislocations. We obtain the hydrodynamic mode spectrum and correlation
functions in various regimes in order to identify the signatures of plasticity
in electronic crystal phases. In particular, we show that proliferation of
dislocations de-pins the spatially resolved conductivity until the crystal
melts, after which point a new phase of a pinned electronic liquid emerges. In
addition, the mode spectrum exhibits a competition between pinning and
plasticity effects, with the damping rate of some modes being controlled by
pinning-induced phase relaxation and some by plasticity-induced strain
relaxation. We find that the recently discovered damping-attenuation relation
continues to hold for pinned-induced phase relaxation even in the presence of
plasticity and dislocations. We also comment on various experimental setups
that could probe the effects of plasticity. The framework developed here is
applicable to a large class of physical systems including electronic Wigner
crystals, multicomponent charge density waves, and ordinary crystals.Comment: v1: 34pp, 7fig
A Multi Criteria Decision Analytic (MCDA) approach to combining evidence and patient preferences for cancer prevention and treatment: an application to prostate cancer screening
A 72-year-old man, edentulous in the maxilla for 20 years, presented himself at his dentist in 2006 with complaints concerning retention of his upper denture. The placement of implants was only possible if bone augmentation was undertaken; this was definitively rejected by the man. As an alternative, Muchor anchors were placed, but these did not provide an adequate solution to the retention problem. In the end, 2 palatal implants were placed, with magnetic anchoring. One year later, the man was very satisfied with this solution
The cleavage surface of the BaFe_(2-x)Co_(x)As_(2) and Fe_(y)Se_(1-x)Te_(x) superconductors: from diversity to simplicity
We elucidate the termination surface of cleaved single crystals of the
BaFe_(2-x)Co_(x)As_(2) and Fe_(y)Se_(1-x)Te_(x) families of the high
temperature iron based superconductors. By combining scanning tunneling
microscopic data with low energy electron diffraction we prove that the
termination layer of the Ba122 systems is a remnant of the Ba layer, which
exhibits a complex diversity of ordered and disordered structures. The observed
surface topographies and their accompanying superstructure reflections in
electron diffraction depend on the cleavage temperature. In stark contrast,
Fe_(y)Se_(1-x)Te_(x) possesses only a single termination structure - that of
the tetragonally ordered Se_(1-x)Te_(x) layer.Comment: 4 pages, 4 figure
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