11,469 research outputs found
Prognosis of Lung Cancer Mortality in West Germany: A Case Study in Bayesian Prediction. (REVISED, January 2000)
We apply a generalized Bayesian age-period-cohort (APC) model to a dataset on lung cancer mortality in West Germany, 1952-1996. Our goal is to predict future deaths rates until the year 2010, separately for males and females. Since age and period is not measured on the same grid, we propose a generalized APC-model where consecutive cohort parameters represent strongly overlapping birth cohorts. This approach results in a rather large number of parameters, where standard algorithms for statistical inference by Markov chain Monte Carlo (MCMC) methods turn out to be computationally intensive. We propose a more efficient implementation based on ideas of block sampling from the time series literature. We entertain two different formulations, penalizing either first or second differences of age, period and cohort parameters. To assess the predictive quality of both formulations, we first forecast the rates for the period 1987-1996 based on data until 1986. A comparison with the actual observed rates is made based on quantities related to the predictive deviance. Predictions of lung cancer mortality until 2010 both for males and females are finally reported
Comparing pertinent effects of antiferromagnetic fluctuations in the two and three dimensional Hubbard model
We use the dynamical vertex approximation (DA) with a Moriyaesque correction for studying the impact of antiferromagnetic fluctuations
on the spectral function of the Hubbard model in two and three dimensions. Our
results show the suppression of the quasiparticle weight in three dimensions
and dramatically stronger impact of spin fluctuations in two dimensions where
the pseudogap is formed at low enough temperatures. Even in the presence of the
Hubbard subbands, the origin of the pseudogap at weak-to-intermediate coupling
is in the splitting of the quasiparticle peak. At stronger coupling (closer to
the insulating phase) the splitting of Hubbard subbands is expected instead.
The -dependence of the self energy appears to be also much more
pronounced in two dimensions as can be observed in the -resolved
DA spectra, experimentally accessible by angular resolved photoemission
spectroscopy in layered correlated systems.Comment: 10 pages, 12 figure
Projective Quantum Monte Carlo Method for the Anderson Impurity Model and its Application to Dynamical Mean Field Theory
We develop a projective quantum Monte Carlo algorithm of the Hirsch-Fye type
for obtaining ground state properties of the Anderson impurity model. This
method is employed to solve the self-consistency equations of dynamical mean
field theory. It is shown that the approach converges rapidly to the ground
state so that reliable zero-temperature results are obtained. As a first
application, we study the Mott-Hubbard metal-insulator transition of the
one-band Hubbard model, reconfirming the numerical renormalization group
results.Comment: 4 pages, 4 figure
A continuous population of variable stars up to about 1.5 mag above the horizontal branch?
Increasing samples of pulsating variable stars populating the classical
instability strip from the horizontal branch to a few magnitudes brighter are
being found in several Local Group galaxies, irrespective of the galaxy
morphological type. We will review the observational scenario focusing in
particular on the Anomalous Cepheids and related objects.Comment: 5 pages, 2 figures, invited review in JENAM 2003, "Minisymposium:
Asteroseismology and Stellar Evolution", Communications in Asteroseismology,
in pres
- …