468 research outputs found
Voters punish politicians for misinformation that portrays them in a favourable light, but not for inaccurate information that attacks their opponents.
What impact does inaccurate information have on political campaigning? Outlining the results of three studies on the role of misinformation in politics, Michael D. Cobb finds that voters react to positive and negative information in very different ways. While negative misinformation, such as using false figures to attack a political opponent, tends to linger in the minds of voters even after it is retracted; there is no such effect when positive information about a politician is debunked. Indeed, voters appear to actively punish politicians in the aftermath of positive misinformation
State-level corruption scandals do little to change voters’ minds about political parties.
Political corruption scandals seem to have become commonplace in American politics and the state-level is no exception. But do such scandals hurt the affected party at the ballot box? In new research which examines the effects of corruption scandals in North Carolina, Michael D. Cobb and Andrew J. Taylor find that voters are generally unable to identify the scandalous politician or their party. They argue that corruption scandals do little to affect a party’s vote, and that citizens tend to base their voting choices on other matters
Simplex Solutions for Optimal Control Flight Paths in Urban Environments
This paper identifies feasible fight paths for Small Unmanned Aircraft Systems in a highly constrained environment. Optimal control software has long been used for vehicle path planning and has proven most successful when an adequate initial guess is presented flight to an optimal control solver. Leveraging fast geometric planning techniques, a large search space is discretized into a set of simplexes where a Dubins path solution is generated and contained in a polygonal search corridor free of path constraints. Direct optimal control methods are then used to determine the optimal flight path through the newly defined search corridor. Two scenarios are evaluated. The first is limited to heading rate control only, requiring the air vehicle to maintain constant speed. The second allows for velocity control which permits slower speeds, reducing the vehicles minimum turn radius and increasing the search domain. Results illustrate the benefits gained when including speed control to path planning algorithms by comparing trajectory and convergence times, resulting in a reliable, hybrid solution method to the SUAS constrained optimal control problem
An Ensemble of Bayesian Neural Networks for Exoplanetary Atmospheric Retrieval
Machine learning is now used in many areas of astrophysics, from detecting
exoplanets in Kepler transit signals to removing telescope systematics. Recent
work demonstrated the potential of using machine learning algorithms for
atmospheric retrieval by implementing a random forest to perform retrievals in
seconds that are consistent with the traditional, computationally-expensive
nested-sampling retrieval method. We expand upon their approach by presenting a
new machine learning model, \texttt{plan-net}, based on an ensemble of Bayesian
neural networks that yields more accurate inferences than the random forest for
the same data set of synthetic transmission spectra. We demonstrate that an
ensemble provides greater accuracy and more robust uncertainties than a single
model. In addition to being the first to use Bayesian neural networks for
atmospheric retrieval, we also introduce a new loss function for Bayesian
neural networks that learns correlations between the model outputs.
Importantly, we show that designing machine learning models to explicitly
incorporate domain-specific knowledge both improves performance and provides
additional insight by inferring the covariance of the retrieved atmospheric
parameters. We apply \texttt{plan-net} to the Hubble Space Telescope Wide Field
Camera 3 transmission spectrum for WASP-12b and retrieve an isothermal
temperature and water abundance consistent with the literature. We highlight
that our method is flexible and can be expanded to higher-resolution spectra
and a larger number of atmospheric parameters
2013-14 Guest Artist Series: American Brass Quintet
Kennesaw State University School of Music presents the American Brass Quintet.https://digitalcommons.kennesaw.edu/musicprograms/1385/thumbnail.jp
2011-2012 Collaborative Spotlight: The American Brass Quintet
Past Collaborative Spotlight Concerts 2011 - Duo Pianists Leonard and Shenhttps://spiral.lynn.edu/conservatory_otherseasonalconcerts/1017/thumbnail.jp
Accurate Machine Learning Atmospheric Retrieval via a Neural Network Surrogate Model for Radiative Transfer
Atmospheric retrieval determines the properties of an atmosphere based on its
measured spectrum. The low signal-to-noise ratio of exoplanet observations
require a Bayesian approach to determine posterior probability distributions of
each model parameter, given observed spectra. This inference is computationally
expensive, as it requires many executions of a costly radiative transfer (RT)
simulation for each set of sampled model parameters. Machine learning (ML) has
recently been shown to provide a significant reduction in runtime for
retrievals, mainly by training inverse ML models that predict parameter
distributions, given observed spectra, albeit with reduced posterior accuracy.
Here we present a novel approach to retrieval by training a forward ML
surrogate model that predicts spectra given model parameters, providing a fast
approximate RT simulation that can be used in a conventional Bayesian retrieval
framework without significant loss of accuracy. We demonstrate our method on
the emission spectrum of HD 189733 b and find good agreement with a traditional
retrieval from the Bayesian Atmospheric Radiative Transfer (BART) code
(Bhattacharyya coefficients of 0.9843--0.9972, with a mean of 0.9925, between
1D marginalized posteriors). This accuracy comes while still offering
significant speed enhancements over traditional RT, albeit not as much as ML
methods with lower posterior accuracy. Our method is ~9x faster per parallel
chain than BART when run on an AMD EPYC 7402P central processing unit (CPU).
Neural-network computation using an NVIDIA Titan Xp graphics processing unit is
90--180x faster per chain than BART on that CPU.Comment: 16 pages, 4 figures, submitted to PSJ 3/4/2020, revised 1/22/2021.
Text restructured and updated for clarity, model updated and expanded to work
for range of hot Jupiters, results/plots updated, two new appendices to
further justify model selection and methodolog
Far Ultraviolet Absolute Flux of alpha Virginis
We present the far ultraviolet spectrum of alpha Virginis taken with EURD
spectrograph on-board MINISAT-01. The spectral range covered is from ~900 to
1080 A with 5 A spectral resolution. We have fitted Kurucz models to IUE
spectra of alpha Vir and compared the extension of the model to our wavelengths
with EURD data. This comparison shows that EURD fluxes are consistent with the
prediction of the model within 20-30%, depending on the reddening assumed. EURD
fluxes are consistent with Voyager observations but are ~60% higher than most
previous rocket observations of alpha Vir.Comment: 13 pages, 4 figures. Submitted to The Astrophysical Journa
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