Absolute Ages and Distances of 22 GCs using Monte Carlo Main-Sequence Fitting

The recent Gaia Data Release 1 of stellar parallaxes provides ample opportunity to find metal-poor main-sequence stars with precise parallaxes. We select 21 such stars with parallax uncertainties better than $\sigma_\pi/\pi\leq0.10$ and accurate abundance determinations suitable for testing metal-poor stellar evolution models and determining the distance to Galactic globular clusters. A Monte Carlo analysis was used, taking into account uncertainties in the model construction parameters, to generate stellar models and isochrones to fit to the calibration stars. The isochrones which fit the calibration stars best were then used to determine the distances and ages of 22 globular clusters with metallicities ranging from -2.4 dex to -0.7 dex. We find distances with an average uncertainty of 0.15 mag and absolute ages ranging from 10.8 - 13.6 Gyr with an average uncertainty of 1.6 Gyr. Using literature proper motion data we calculate orbits for the clusters finding six that reside within the Galactic disk/bulge while the rest are considered halo clusters. We find no strong evidence for a relationship between age and Galactocentric distance, but we do find a decreasing age-[Fe/H] relation.Comment: 17 pages, 8 tables, 6 figures, accepted in Ap

Betting and Belief: Prediction Markets and Attribution of Climate Change

Despite much scientific evidence, a large fraction of the American public doubts that greenhouse gases are causing global warming. We present a simulation model as a computational test-bed for climate prediction markets. Traders adapt their beliefs about future temperatures based on the profits of other traders in their social network. We simulate two alternative climate futures, in which global temperatures are primarily driven either by carbon dioxide or by solar irradiance. These represent, respectively, the scientific consensus and a hypothesis advanced by prominent skeptics. We conduct sensitivity analyses to determine how a variety of factors describing both the market and the physical climate may affect traders' beliefs about the cause of global climate change. Market participation causes most traders to converge quickly toward believing the "true" climate model, suggesting that a climate market could be useful for building public consensus.Comment: All code and data for the model is available at http://johnjnay.com/predMarket/. Forthcoming in Proceedings of the 2016 Winter Simulation Conference. IEEE Pres

Development of a space stable thermal control coatings for use in large space vehicles

The preparation and evaluation of zinc orthotitanate and of several new pigments and the environmental testing and evaluation of these pigments and of coatings made from them constitute the bulk of the work accomplished. New pigments were prepared and EPR spectra of pigments and their precursor compounds studied. Results of extensive testing of commercially-available, strippable, protective coatings are reported; Owens-Illinois 650 glass resin has been stabilized against progressive mechanical failures; and definite improvements have been noted. A zinc oxide pigmented lithium silicate paint has demonstrated very good ultraviolet stability

Development of space stable thermal control coatings for use on large space vehicles

The evaluation and environmental testing of zinc orthotitanate pigments for use as space stable thermal control coatings on large space vehicles are discussed. Electron paramagnetic resonance spectra of the pigments and their precursor compounds are examined. A continuing study of the spectral intensity of mercury-argon and mercury-xenon sources in reported. Results of long term environmental testing of commercially available, strippable, protective coatings are discussed

Assessment of Management Effectiveness for the Strategic Assessment of the Great Barrier Reef Region

[Extract] As part of the strategic assessment of the Great Barrier Reef World Heritage Area and adjacent coastal zone, the Great Barrier Reef Marine Park Authority is required to assess the effectiveness of its management arrangements to protect the values that underpin matters of national environmental significance within the Great Barrier Reef Region.Title page: Prepared for the Great Barrier Reef Marine Park Authority (GBRMPA) -- 19 March 2013 -- UniQuest Project No: C0094

Epidemics in Networks of Spatially Correlated Three-dimensional Root Branching Structures

Using digitized images of the three-dimensional, branching structures for root systems of bean seedlings, together with analytical and numerical methods that map a common 'SIR' epidemiological model onto the bond percolation problem, we show how the spatially-correlated branching structures of plant roots affect transmission efficiencies, and hence the invasion criterion, for a soil-borne pathogen as it spreads through ensembles of morphologically complex hosts. We conclude that the inherent heterogeneities in transmissibilities arising from correlations in the degrees of overlap between neighbouring plants, render a population of root systems less susceptible to epidemic invasion than a corresponding homogeneous system. Several components of morphological complexity are analysed that contribute to disorder and heterogeneities in transmissibility of infection. Anisotropy in root shape is shown to increase resilience to epidemic invasion, while increasing the degree of branching enhances the spread of epidemics in the population of roots. Some extension of the methods for other epidemiological systems are discussed.Comment: 21 pages, 8 figure

Forks in the Road

This Essay outlines a simple heuristic that will enable public and private policymakers to focus on the most important climate change mitigation strategies. Policymakers face a dizzying array of information, pressure from advocacy groups, and policy options, and it is easy to lose sight of the forest for the trees. Many policy options are attractive on the surface but either fail to meaningfully address the problem or are unlikely to be adopted in the foreseeable future. If policymakers make the right decision when confronting three essential choices or forks in the road, though, the result will be 60% to 70% reductions in greenhouse gas emissions, an amount that will keep widely-adopted climate mitigation goals in reach. The three options are decarbonization of the electrical grid, electrification of the motor vehicle fleet, and electrification of buildings. International, national, and subnational officials, philanthropists, corporate executives, advocacy group leaders, and households all have the ability to prioritize these three options in their regulatory, purchasing, and other actions. If they choose these three decarbonatization options, many other mistakes can be made without jeopardizing the achievement of widely adopted emissions targets. If they make the wrong choice, however, few combinations of other viable options can achieve the necessary reductions. In the face of a growing consensus that immediate, major emissions reductions are required, the forks in the road heuristic can provide policymakers with the framework necessary to make smart decisions and ignore the noise surrounding climate law and policy