4,199 research outputs found
Strong impact of light induced conical intersections on the spectrum of diatomic molecules
We show that dressing of diatomic molecules by running laser waves gives rise
to conical intersections (CIs). Due to presence of such CIs, the rovibronic
molecular motions are strongly coupled. A pronounced impact of the CI on the
spectrum of molecule is demonstrated via numerical calculation for weak
and moderate laser intensity, and an experiment is suggested on this basis. The
position of the light induced CI and the strength of its non-adiabatic
couplings can be chosen by changing the frequency and intensity of the used
running laser wave. This offers new possibilities to control the photo-induced
rovibronic molecular dynamics.Comment: 4 pages, 7 figure
Depressive Deficits in Recognition: Dissociation of Recollection and Familiarity
Dysphoric and nondysphoric students (48 women and 24 men) participated in an experiment that was designed to separate automatic and controlled uses of memory in a modified recognition paradigm. First, they judged the relation of target words to paired words. Later they made recognition decisions on target items alone or in the context of the original paired item. The use of L.L. Jacoby\u27s (1991) process dissociation procedure revealed depressive deficits in estimates of recollection but not in estimates of familiarity. The paired test improved recollection for all subjects and showed a trend in the direction of increased familiarity. These outcomes support approaches to depressive cognition that emphasize impaired cognitive control
Spatial data modeling by means of Gibbs Markov random fields based on a generalized planar rotator model
We introduce a Gibbs Markov random field for spatial data on Cartesian grids
which is based on the generalized planar rotator (GPR) model. The GPR model
generalizes the recently proposed modified planar rotator (MPR) model by
including in the Hamiltonian additional terms that better capture realistic
features of spatial data, such as smoothness, non-Gaussianity, and geometric
anisotropy. In particular, the GPR model includes up to infinite number of
higher-order harmonics with exponentially vanishing interaction strength,
directional dependence of the bilinear interaction term between nearest grid
neighbors, longer-distance neighbor interactions, and two types of an external
bias field. Hence, in contrast with the single-parameter MPR model, the GPR
model features five additional parameters: the number of higher-order terms
and the parameter controlling their decay rate, the exchange
anisotropy parameter , the further-neighbor interaction coupling
, and the external field (bias) parameters (or ). We present
numerical tests on various synthetic data which demonstrate the effects of the
respective terms on the model's prediction performance and we discuss these
results in connection with the data properties.Comment: 29 pages, 9 figure
A parsimonious, computationally efficient machine learning method for spatial regression
We introduce the modified planar rotator method (MPRS), a physically inspired
machine learning method for spatial/temporal regression. MPRS is a
non-parametric model which incorporates spatial or temporal correlations via
short-range, distance-dependent ``interactions'' without assuming a specific
form for the underlying probability distribution. Predictions are obtained by
means of a fully autonomous learning algorithm which employs equilibrium
conditional Monte Carlo simulations. MPRS is able to handle scattered data and
arbitrary spatial dimensions. We report tests on various synthetic and
real-word data in one, two and three dimensions which demonstrate that the MPRS
prediction performance (without parameter tuning) is competitive with standard
interpolation methods such as ordinary kriging and inverse distance weighting.
In particular, MPRS is a particularly effective gap-filling method for rough
and non-Gaussian data (e.g., daily precipitation time series). MPRS shows
superior computational efficiency and scalability for large samples. Massive
data sets involving millions of nodes can be processed in a few seconds on a
standard personal computer.Comment: 42 pages, 15 figure
Are steady magnetospheric convection events prolonged substorms?
Magnetospheric modes, including substorms, sawtooth events, and steady magnetospheric convection events, have in the past been described as different responses of the magnetosphere to coupling with the solar wind. Using previously determined event lists for sawtooth events, steady magnetospheric convection events, and substorms, we produce a statistical study of these event types to examine their similarities and behavior in terms of solar wind parameters, auroral brightness, open magnetospheric flux, and geomagnetic indices. A superposed epoch analysis shows that individual sawteeth show the same signatures as substorms but occur during more extreme cases of solar wind driving as well as geomagnetic activity. We also explore the limitations of current methods of identifying steady magnetospheric convection events and explain why some of those events are flagged inappropriately. We show that 58% of the steady magnetospheric convection events considered, as identified by criteria defined in previous studies are part of a prolonged version of substorms due to continued dayside driving during expansion phase. The remaining 42% are episodes of enhanced magnetospheric convection, occurring after extended periods of dayside driving
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