37,873 research outputs found
Semiparametric Bayesian Time-Space Analysis of Unemployment Duration
In this paper, we analyze unemployment duration in Germany with official data from the German Federal Employment Office for the years 1980-1995. Conventional hazard rate models for leaving unemployment cannot cope with simultaneous and flexible fitting of duration dependence, nonlinear covariate effects, trend and seasonal calendar time components and a large number of regional effects. We apply a semiparametric hierarchical Bayesian modelling approach that is suitable for time-space analysis of unemployment duration by simultaneously including and estimating effects of several time scales, regional variation and further covariates. Inference is fully Bayesian and uses recent Markov chain Monte Carlo techniques
A Laplace Transform Method for Molecular Mass Distribution Calculation from Rheometric Data
Polydisperse linear polymer melts can be microscopically described by the
tube model and fractal reptation dynamics, while on the macroscopic side the
generalized Maxwell model is capable of correctly displaying most of the
rheological behavior. In this paper, a Laplace transform method is derived and
different macroscopic starting points for molecular mass distribution
calculation are compared to a classical light scattering evaluation. The
underlying assumptions comprise the modern understanding on polymer dynamics in
entangled systems but can be stated in a mathematically generalized way. The
resulting method is very easy to use due to its mathematical structure and it
is capable of calculating multimodal molecular mass distributions of linear
polymer melts
Tilted-mirror semiconductor lasers
Broad-area GaAs heterostructure lasers with a tilted mirror were demonstrated for the first time, with the tilted mirror fabricated by etching. These lasers operate in a smooth and stable single lateral mode with a high degree of spatial coherence. The suppression of filamentation manifests itself in a high degree of reproducibility in the near-field pattern
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Role of government policy in nutrition-barriers to and opportunities for healthier eating
Observation of Entanglement Between Itinerant Microwave Photons and a Superconducting Qubit
A localized qubit entangled with a propagating quantum field is well suited
to study non-local aspects of quantum mechanics and may also provide a channel
to communicate between spatially separated nodes in a quantum network. Here, we
report the on demand generation and characterization of Bell-type entangled
states between a superconducting qubit and propagating microwave fields
composed of zero, one and two-photon Fock states. Using low noise linear
amplification and efficient data acquisition we extract all relevant
correlations between the qubit and the photon states and demonstrate
entanglement with high fidelity.Comment: 5 pages, 3 figure
The nature of Ho magnetism in multiferroic HoMnO3
Using x-ray resonant magnetic scattering and x-ray magnetic circular
dichroism, techniques that are element specific, we have elucidated the role of
Ho3+ in multiferroic HoMnO3. In zero field, Ho3+ orders antiferromagnetically
with moments aligned along the hexagonal c direction below 40 K, and undergoes
a transition to another magnetic structure below 4.5 K. In applied electric
fields of up to 1x10^7 V/m, the magnetic structure of Ho3+ remains unchanged.Comment: 4 pages, 3 figures Manuscript accepted for publication in Phys. Rev.
Lett. 200
Low-energy models for correlated materials: bandwidth renormalization from Coulombic screening
We provide a prescription for constructing Hamiltonians representing the low
energy physics of correlated electron materials with dynamically screened
Coulomb interactions. The key feature is a renormalization of the hopping and
hybridization parameters by the processes that lead to the dynamical screening.
The renormalization is shown to be non-negligible for various classes of
correlated electron materials. The bandwidth reduction effect is necessary for
connecting models to materials behavior and for making quantitative predictions
for low-energy properties of solids.Comment: 4 pages, 2 figure
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