4,327 research outputs found
Fundamental Aspects of Quantum Brownian Motion
With this work we elaborate on the physics of quantum noise in thermal
equilibrium and in stationary non-equilibrium. Starting out from the celebrated
quantum fluctuation-dissipation theorem we discuss some important consequences
that must hold for open, dissipative quantum systems in thermal equilibrium.
The issue of quantum dissipation is exemplified with the fundamental problem of
a damped harmonic quantum oscillator. The role of quantum fluctuations is
discussed in the context of both, the nonlinear generalized quantum Langevin
equation and the path integral approach. We discuss the consequences of the
time-reversal symmetry for an open dissipative quantum dynamics and,
furthermore, point to a series of subtleties and possible pitfalls. The path
integral methodology is applied to the decay of metastable states assisted by
quantum Brownian noise.Comment: 13 pages, 4 figures, RevTeX, submitted to Chaos special issue "100
Years of Brownian Motion
A high-entropy wind r-process study based on nuclear-structure quantities from the new finite-range droplet model FRDM(2012)
Theoretical studies of the nucleosynthesis origin of the heavy elements in
our Solar System (S.S.) by the rapid neutron-capture process (r-process) still
face the entwined uncertainties in the possible astrophysical scenarios and the
nuclear-physics properties far from stability. In this paper we present results
from the investigation of an r-process in the high-entropy wind (HEW) of
core-collapse supernovae (here chosen as one of the possible scenarios for this
nucleosynthesis process), using new nuclear-data input calculated in a
consistent approach, for masses and -decay properties from the new
finite-range droplet model FRDM(2012). The accuracy of the new mass model is
0.56 MeV with respect to {\sc AME2003}, to which it was adjusted. We compare
the new HEW r-process abundance pattern to the latest S.S. r-process residuals
and to our earlier calculations with the nuclear-structure quantities based on
FRDM(1992). Substantial overall and specific local improvements in the
calculated pattern of the r-process between and Bi, as
well as remaining deficiencies are discussed in terms of the underlying
spherical and deformed shell structure far from stability.Comment: 8 pages, 4 figure
SPINON BASIS FOR (sl2^)_k INTEGRABLE HIGHEST WEIGHT MODULES AND NEW CHARACTER FORMULAS
In this note we review the spinon basis for the integrable highest weight
modules of sl2^ at levels k\geq1, and give the corresponding character formula.
We show that our spinon basis is intimately related to the basis proposed by
Foda et al. in the principal gradation of the algebra. This gives rise to new
identities for the q-dimensions of the integrable modules.Comment: 9 pages, plain TeX + amssym.def, to appear in the proceedings of
`Statistical Mechanics and Quantum Field Theory,' USC, May 16-21, 199
Detection of risk factors for obesity in early childhood with quantile regression methods for longitudinal data
This article compares and discusses three different statistical methods for investigating risk factors for overweight and obesity in early childhood by means of the LISA study, a recent German birth cohort study with 3097 children. Since the definition of overweight and obesity is typically based on upper quantiles (90% and 97%) of the age specific body mass index (BMI) distribution, our aim was to model the influence of risk factors and age on these quantiles while as far as possible taking the longitudinal data structure into account. The following statistical regression models were chosen: additive mixed models, generalized additive models for location, scale and shape (GAMLSS), and distribution free quantile regression models. The methods were compared empirically by cross-validation and for the data at hand no model could be rated superior. Motivated by previous studies we explored whether there is an age-specific skewness of the BMI distribution. The investigated data does not suggest such an effect, even after adjusting for risk factors. Concerning risk factors, our results mainly confirm results obtained in previous studies. From a methodological point of view, we conclude that GAMLSS and distribution free quantile regression are promising approaches for longitudinal quantile regression, requiring, however, further extensions to fully account for longitudinal data structures
Quantum Mechanical Propagators in Terms of Hida Distributions
We review some basic notions and results of White Noise Analysis that are
used in the construction of the Feynman integrand as a generalized White Noise
functional. After sketching this construction for a large class of potentials
we show that the resulting Feynman integrals solve the Schroedinger equation
How (Not) to Discourage the Unscrupulous Copyist
This article explores how the U.S. and Japanese courts implement the doctrine of equivalents when determining patent infringement. The doctrine of equivalents is a balance of, on one hand, the public\u27s interest to know the metes and bounds of the patent, and on the other hand, the private interest of the patentee to be granted a sufficient scope for the granted patent. After comparing and contrasting the implementation of the doctrine in Japan and the United States, I propose a new method that places the burden on the patent practitioner, before infringement proceedings begin, to determine the proper scope of the paten
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