6,162 research outputs found
Solitary waves and their stability in colloidal media: semi-analytical solutions
Spatial solitary waves in colloidal suspensions of spherical dielectric
nanoparticles are considered. The interaction of the nanoparticles is modelled
as a hard-sphere gas, with the Carnahan-Starling formula used for the gas
compressibility. Semi-analytical solutions, for both one and two spatial
dimensions, are derived using an averaged Lagrangian and suitable trial
functions for the solitary waves. Power versus propagation constant curves and
neutral stability curves are obtained for both cases, which illustrate that
multiple solution branches occur for both the one and two dimensional
geometries. For the one-dimensional case it is found that three solution
branches (with a bistable regime) occur, while for the two-dimensional case two
solution branches (with a single stable branch) occur in the limit of low
background packing fractions. For high background packing fractions the power
versus propagation constant curves are monotonic and the solitary waves stable
for all parameter values. Comparisons are made between the semi-analytical and
numerical solutions, with excellent comparison obtained.Comment: Paper to appear in Dynamics of Continuous, Discrete and Impulsive
Systems, Series
Data management study, volume 5. Appendix E - Contractor data package quality assurance /QA/ Final report
Manufacturing verification tests for quality assurance and control data management on Voyager spacecraf
Variable Selection and Model Averaging in Semiparametric Overdispersed Generalized Linear Models
We express the mean and variance terms in a double exponential regression
model as additive functions of the predictors and use Bayesian variable
selection to determine which predictors enter the model, and whether they enter
linearly or flexibly. When the variance term is null we obtain a generalized
additive model, which becomes a generalized linear model if the predictors
enter the mean linearly. The model is estimated using Markov chain Monte Carlo
simulation and the methodology is illustrated using real and simulated data
sets.Comment: 8 graphs 35 page
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Sensory dominance and multisensory integration as screening tools in aging
Multisensory information typically confers neural and behavioural advantages over unisensory information. We used a simple audio-visual detection task to compare healthy young (HY), healthy older (HO) and mild-cognitive impairment (MCI) individuals. Neuropsychological tests assessed individuals' learning and memory impairments. First, we provide much-needed clarification regarding the presence of enhanced multisensory benefits in both healthily and abnormally aging individuals. The pattern of sensory dominance shifted with healthy and abnormal aging to favour a propensity of auditory-dominant behaviour (i.e., detecting sounds faster than flashes). Notably, multisensory benefits were larger only in healthy older than younger individuals who were also visually-dominant. Second, we demonstrate that the multisensory detection task offers benefits as a time- and resource-economic MCI screening tool. Receiver operating characteristic (ROC) analysis demonstrated that MCI diagnosis could be reliably achieved based on the combination of indices of multisensory integration together with indices of sensory dominance. Our findings showcase the importance of sensory profiles in determining multisensory benefits in healthy and abnormal aging. Crucially, our findings open an exciting possibility for multisensory detection tasks to be used as a cost-effective screening tool. These findings clarify relationships between multisensory and memory functions in aging, while offering new avenues for improved dementia diagnostics
A Quantitative Comparison of Opacities Calculated Using the Distorted- Wave and -Matrix Methods
The present debate on the reliability of astrophysical opacities has reached
a new climax with the recent measurements of Fe opacities on the Z-machine at
the Sandia National Laboratory \citep{Bailey2015}. To understand the
differences between theoretical results, on the one hand, and experiments on
the other, as well as the differences among the various theoretical results,
detailed comparisons are needed. Many ingredients are involved in the
calculation of opacities; deconstructing the whole process and comparing the
differences at each step are necessary to quantify their importance and impact
on the final results. We present here such a comparison using the two main
approaches to calculate the required atomic data, the -Matrix and
distorted-wave methods, as well as sets of configurations and coupling schemes
to quantify the effects on the opacities for the and ions.Comment: 10 pages, 2 figure
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Potential sinks for geologic storage of carbon dioxide generated by power plants in North and South Carolina
Duke Energy
Progress Energy
Santee Cooper Power
SCANA CorporationBureau of Economic Geolog
Nuclear magnetic resonance measurements reveal the origin of the Debye process in monohydroxy alcohols
Monohydroxy alcohols show a structural relaxation and at longer time scales a
Debye-type dielectric peak. From spin-lattice relaxation experiments using
different nuclear probes an intermediate, slower-than-structural dynamics is
identified for n-butanol. Based on these findings and on diffusion
measurements, a model of self-restructuring, transient chains is proposed. The
model is demonstrated to explain consistently the so far puzzling observations
made for this class of hydrogen-bonded glass forming liquids.Comment: 4 pages, 4 figure
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