3,551 research outputs found
The East End, the West End, and King's Cross: On Clustering in the Four-Player Hotelling Game
We study experimentally a standard four-player Hotelling game, with a uniform density of consumers and inelastic demand. The pure strategy Nash equilibrium configuration consists of two firms located at one quarter of the ``linear city'', and the other two at three quarters. We do not observe convergence to such an equilibrium. In our experimental data we find three clusters. Besides the direct proximity of the two equilibrium locations this concerns the focal mid-point. Moreover, we observe that whereas this mid-point appears to become more notable over time, other focal points fade away. We explain how these observations are related to best-response dynamics, and to the fact that the players rely on best-responses in particular when they are close to the equilibrium configuration.Location model, Nonconvergence, Focal point, Best-response dynamics
Energy-Momentum Complex in M\o ller's Tetrad Theory of Gravitation
M\o ller's Tetrad Theory of Gravitation is examined with regard to the
energy-momentum complex. The energy-momentum complex as well as the
superpotential associated with M\o ller's theory are derived. M\o ller's field
equations are solved in the case of spherical symmetry. Two different
solutions, giving rise to the same metric, are obtained. The energy associated
with one solution is found to be twice the energy associated with the other.
Some suggestions to get out of this inconsistency are discussed at the end of
the paper.Comment: LaTeX2e with AMS-LaTeX 1.2, 13 page
General relations of heavy quark-antiquark potentials induced by reparameterization invariance
A set of general relations between the spin-independent and spin-dependent
potentials of heavy quark and anti-quark interactions are derived from
reparameterization invariance in the Heavy Quark Effective Theory. It covers
the Gromes relation and includes some new interesting relations which are
useful in understanding the spin-independent and spin-dependent relativistic
corrections to the leading order nonrelativistic potential.Comment: 11 pages, TUIMP-TH-93/54, CCAST-93-3
Target mass number dependence of subthreshold antiproton production in proton-, deuteron- and alpha-particle-induced reactions
Data from KEK on subthreshold \bar{\mrm{p}} as well as on and
\mrm{K}^\pm production in proton-, deuteron- and -induced reactions
at energies between 2.0 and 12.0 A GeV for C, Cu and Pb targets are described
within a unified approach. We use a model which considers a nuclear reaction as
an incoherent sum over collisions of varying numbers of projectile and target
nucleons. It samples complete events and thus allows for the simultaneous
consideration of all final particles including the decay products of the
nuclear residues. The enormous enhancement of the \bar{\mrm{p}} cross
section, as well as the moderate increase of meson production in deuteron and
induced compared to proton-induced reactions, is well reproduced for
all target nuclei. In our approach, the observed enhancement near the
production threshold is mainly due to the contributions from the interactions
of few-nucleon clusters by simultaneously considering fragmentation processes
of the nuclear residues. The ability of the model to reproduce the target mass
dependence may be considered as a further proof of the validity of the cluster
concept.Comment: 9 pages, 4 figure
A relativistic parton cascade with radiation
We consider the evolution of a parton system which is formed at the central
rapidity region just after an ultrarelativistic heavy ion collision. The
evolution of the system, which is composed of gluons, quarks and antiquarks, is
described by a relativistic Boltzmann equations with collision terms including
radiation and retardation effects. The equations are solved by the test
particle method using Monte-Carlo sampling. Our simulations do not show any
evidence of kinetic equilibration, unless the cross sections are artificially
increased to unrealistically large values.Comment: 14 pages, 4 figure
On the dependence between UV luminosity and Lyman-alpha equivalent width in high redshift galaxies
We show that with the simple assumption of no correlation between the
Ly-alpha equivalent width and the UV luminosity of a galaxy, the observed
distribution of high redshift galaxies in an equivalent width - absolute UV
magnitude plane can be reproduced. We further show that there is no dependence
between Ly-alpha equivalent width and Ly-alpha luminosity in a sample of
Ly-alpha emitters. The test was expanded to Lyman-break galaxies and again no
dependence was found. Simultaneously, we show that a recently proposed lack of
large equivalent width, UV bright galaxies (Ando et al. 2006) can be explained
by a simple observational effect, based on too small survey volumes.Comment: 7 pages, 3 figures, 2 tables, accepted in MNRA
Cardiac evaluation of candidates for kidney transplantation: value of exercise radionuclide angiocardiography
In view of the high incidence and mortality of coronary artery disease (CAD) in patients with kidney transplantation, a systematic cardiac evaluation was prospectively performed in 103 uraemic patients eligible for transplantation. After clinical examination, 28 patients with symptoms of CAD or diabetes mellitus were referred directly for coronary angiography, whereas the remaining 75 patients had rest and exercise radionuclide angiocardiography for evaluation of possible asymptomatic CAD. Among them, left ventricular ejection fraction was below 40% at rest or fell during exercise by at least 5 EF% in 12 patients; coronary angiography in nine showed CAD in four and hypertensive heart disease in five. In the remaining 63 (of 75) patients without severe resting left ventricular dysfunction or exercise ischaemia, the follow-up of 28 ±7 months revealed no clinical manifestation of CAD. Overall incidence of CAD in symptomatic and asymptomatic patients during a follow-up of 27 months after cardiac evaluation was 20 and 25% in non-diabetic and diabetic candidates for kidney transplantation, respectively (P = n.s.). Thus, clinical examination combined with exercise radionuclide angiocardiography in patients without signs or symptoms of heart disease had a high predictive accuracy for presence or absence of late manifestations of CAD. Exercise radionuclide angiocardiography is therefore a useful method for screening kidney transplantation candidates for asymptomatic CA
Profile and width of rough interfaces
In the context of Landau theory and its field theoretical refinements,
interfaces between coexisting phases are described by intrinsic profiles. These
intrinsic interface profiles, however, are neither directly accessible by
experiment nor by computer simulation as they are broadened by long-wavelength
capillary waves. In this paper we study the separation of the small scale
intrinsic structure from the large scale capillary wave fluctuations in the
Monte Carlo simulated three-dimensional Ising model. To this purpose, a
blocking procedure is applied, using the block size as a variable cutoff, and a
translationally invariant method to determine the interface position of
strongly fluctuating profiles on small length scales is introduced. While the
capillary wave picture is confirmed on large length scales and its limit of
validity is estimated, an intrinsic regime is, contrary to expectations, not
observed.Comment: 18 pages, 4 Postscript figures, LaTeX2e, formulation of sec.3.2
improved, 1 reference adde
Information criteria for inhomogeneous spatial point processes
The theoretical foundation for a number of model selection criteria is
established in the context of inhomogeneous point processes and under various
asymptotic settings: infill, increasing domain, and combinations of these. For
inhomogeneous Poisson processes we consider Akaike information criterion and
the Bayesian information criterion, and in particular we identify the point
process analogue of sample size needed for the Bayesian information criterion.
Considering general inhomogeneous point processes we derive new composite
likelihood and composite Bayesian information criteria for selecting a
regression model for the intensity function. The proposed model selection
criteria are evaluated using simulations of Poisson processes and cluster point
processes.Comment: 6 figure
On the Stereochemistry of the Cations in the Doping Block of Superconducting Copper-Oxides
Metal-oxygen complexes containing Cu,- Tl-, Hg-, Bi- and Pb-cations are
electronically active in superconducting copper-oxides by stabilizing single
phases with enhanced , whereas other metal-oxygen complexes deteriorate
copper-oxide superconductivity. Cu, Tl, Hg, Bi, Pb in their actual oxidation
states are closed shell or inert pair ions. Their electronic
configurations have a strong tendency to polarize the oxygen environment. The
closed shell ions with low lying
excitations form linear complexes through hybridization polarizing
the apical oxygens. Comparatively low excitation energies
distinguish from other closed shell
ions deteriorating copper-oxide superconductivity, {\it e.g.} .Comment: 5 pages, uses REVTEX. To be published in: J. Superconductivity, Proc.
Int. Workshop on "Phase Separation, Electronic Inhomogenities and Related
Mechanisms for High T_c Superconductors", Erice (Sicily) 9-15 July 199
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