2,061 research outputs found

    Integrating Information Literacy into the Virtual University: A Course Model

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    published or submitted for publicatio

    FUTURES-BASED PRICE FORECASTS FOR AGRICULTURAL PRODUCERS AND BUSINESSES

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    The forecasting accuracy of five competing naïve and futures-based localized cash price forecasts is determined. The third-week's price each month from 1987-96 is forecasted from several vantage points. Commodities examine include those relevant to Midwest producers: the major grains, slaughter steers, slaughter hogs, several classes of feeder cattle, cull cows, and sows. Relative forecasting accuracy across forecast method is compared using regression models of forecast error. The traditional forecast method deferred futures plus historical basis has the greatest accuracy- even for cull cows. Adding complexity to forecasts, such as including regression models to capture nonlinear bases or biases in futures markets, does not improve accuracy.Demand and Price Analysis,

    IDENTIFYING ECONOMIC RISK IN CATTLE FEEDING

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    Closeout data from two western Kansas commercial feedlots are examined to determine how cattle prices, feed costs, and animal performance impact the variability of cattle feeding profits. The relative impacts of these factors are studied across sex, placement weight, and placement month using standardized beta coefficients. Feeder cattle prices have a greater impact on profit variability for spring and fall placements. The effect of animal performance on variability of cattle feeding profits is greater for fall placements. Results suggest that fed cattle and feeder cattle prices should be emphasized in managing the overall risk in cattle feeding because they are the largest contributors to profit variability.cattle finishing profitability, cattle performance, feedlot closeouts, standardized beta coefficients, Livestock Production/Industries,

    Three-Dimensional Spectral Classification of Low-Metallicity Stars Using Artificial Neural Networks

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    We explore the application of artificial neural networks (ANNs) for the estimation of atmospheric parameters (Teff, logg, and [Fe/H]) for Galactic F- and G-type stars. The ANNs are fed with medium-resolution (~ 1-2 A) non flux-calibrated spectroscopic observations. From a sample of 279 stars with previous high-resolution determinations of metallicity, and a set of (external) estimates of temperature and surface gravity, our ANNs are able to predict Teff with an accuracy of ~ 135-150 K over the range 4250 <= Teff <= 6500 K, logg with an accuracy of ~ 0.25-0.30 dex over the range 1.0 <= logg <= 5.0 dex, and [Fe/H] with an accuracy ~ 0.15-0.20 dex over the range -4.0 <= [Fe/H] <= +0.3. Such accuracies are competitive with the results obtained by fine analysis of high-resolution spectra. It is noteworthy that the ANNs are able to obtain these results without consideration of photometric information for these stars. We have also explored the impact of the signal-to-noise ratio (S/N) on the behavior of ANNs, and conclude that, when analyzed with ANNs trained on spectra of commensurate S/N, it is possible to extract physical parameter estimates of similar accuracy with stellar spectra having S/N as low as 13. Taken together, these results indicate that the ANN approach should be of primary importance for use in present and future large-scale spectroscopic surveys.Comment: 51 pages, 11 eps figures, uses aastex; to appear in Ap

    Improving White Dwarfs as Chronometers with Gaia Parallaxes and Spectroscopic Metallicities

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    White dwarfs (WDs) offer unrealized potential in solving two problems in astrophysics: stellar age accuracy and precision. WD cooling ages can be inferred from surface temperatures and radii, which can be constrained with precision by high-quality photometry and parallaxes. Accurate and precise Gaia parallaxes along with photometric surveys provide information to derive cooling and total ages for vast numbers of WDs. Here we analyze 1372 WDs found in wide binaries with main-sequence (MS) companions and report on the cooling and total age precision attainable in these WD+MS systems. The total age of a WD can be further constrained if its original metallicity is known because the MS lifetime depends on metallicity at fixed mass, yet metallicity is unavailable via spectroscopy of the WD. We show that incorporating spectroscopic metallicity constraints from 38 wide binary MS companions substantially decreases internal uncertainties in WD total ages compared to a uniform constraint. Averaged over the 38 stars in our sample, the total (internal) age uncertainty improves from 21.04% to 16.77% when incorporating the spectroscopic constraint. Higher mass WDs yield better total age precision; for eight WDs with zero-age MS masses \u3e= 2.0 M, the mean uncertainty in total ages improves from 8.61% to 4.54% when incorporating spectroscopic metallicities. We find that it is often possible to achieve 5% total age precision for WDs with progenitor masses above 2.0 M if parallaxes wit

    The WiggleZ Dark Energy Survey: Survey Design and First Data Release

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    The WiggleZ Dark Energy Survey is a survey of 240,000 emission line galaxies in the distant universe, measured with the AAOmega spectrograph on the 3.9-m Anglo-Australian Telescope (AAT). The target galaxies are selected using ultraviolet photometry from the GALEX satellite, with a flux limit of NUV<22.8 mag. The redshift range containing 90% of the galaxies is 0.2<z<1.0. The primary aim of the survey is to precisely measure the scale of baryon acoustic oscillations (BAO) imprinted on the spatial distribution of these galaxies at look-back times of 4-8 Gyrs. Detailed forecasts indicate the survey will measure the BAO scale to better than 2% and the tangential and radial acoustic wave scales to approximately 3% and 5%, respectively. This paper provides a detailed description of the survey and its design, as well as the spectroscopic observations, data reduction, and redshift measurement techniques employed. It also presents an analysis of the properties of the target galaxies, including emission line diagnostics which show that they are mostly extreme starburst galaxies, and Hubble Space Telescope images, which show they contain a high fraction of interacting or distorted systems. In conjunction with this paper, we make a public data release of data for the first 100,000 galaxies measured for the project.Comment: Accepted by MNRAS; this has some figures in low resolution format. Full resolution PDF version (7MB) available at http://www.physics.uq.edu.au/people/mjd/pub/wigglez1.pdf The WiggleZ home page is at http://wigglez.swin.edu.au

    Crop Updates 2005 Oilseeds

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    This session covers fifteen papers from different authors: 1. ACKNOWLEDGEMENTS, Douglas Hamilton, FARMING SYSTEMS DEVELOPMENT OFFICER CROP AGRONOMY AND NUTRITION 2. Canola workshop at Crop Updates 2005, Oilseeds WA, John Duff, EXECUTIVE OFFICER OILSEEDS WA 3. Comparison of IT and TT canola varieties in geographic zones of WA, 2003-4, Graham Walton and Hasan Zaheer, Department of Agriculture 4. Farmer scale canola variety trials in WA, 2004, Graham Walton, John Duff, Neil Harris and Heather Cosgriff, Oilseeds WA 5. Oilseed crops for industrial uses, Margaret C. Campbell, Centre for Legumes in Mediterranean Agriculture (CLIMA), Graham Walton,Department of Agriculture 6. Weed control opportunities with GM canola, Bill Crabtree, Independent Consultant, Northam 7. Soil and tissue tests for the sulfur requirements of canola, R.F. Brennan and M.D.A. Bolland, Department of Agriculture 8. Tests to predict the potassium requirements of canola, R.F. Brennan and M.D.A. Bolland, Department of Agriculture 9. Genotypic variation in potassium efficiency of canola, P.M. Damon and Z. Rengel, Faculty of Natural and Agricultural Sciences, UWA 10. Atrazine contamination of groundwater in the agricultural region of Western Australia, Russell Speed1, Neil Rothnie2, John Simons1, Ted Spadek2 and John Moore1;1Department of Agriculture, 2Chemistry Centre (WA) PESTS AND DISEASES 11. Controlling aphids and Beet western yellows virus in canola using imidacloprid seed dressing, Brenda Coutts and Roger Jones; Department of Agriculture 12. Managing sclerotinia in canola, Neil Harris, Dovuro Seeds Western Australia 13. Slugs, the trail of destruction in canola, Neil Harris, Dovuro Seeds Western Australia 14. Blackleg risk assessment and strategies for risk management in canola during 2005 and beyond, Moin Salam, Ravjit Khanguraand Art Diggle, Department of Agriculture 15. Modelling: BRAT – Blackleg Risk Appraisal Tool, Moin Salam, Ravjit KhanguraDepartment of Agricultur

    Call to action for global access to and harmonization of quality information of individual earth science datasets

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    Knowledge about the quality of data and metadata is important to support informed decisions on the (re)use of individual datasets and is an essential part of the ecosystem that supports open science. Quality assessments reflect the reliability and usability of data. They need to be consistently curated, fully traceable, and adequately documented, as these are crucial for sound decision- and policy-making efforts that rely on data. Quality assessments also need to be consistently represented and readily integrated across systems and tools to allow for improved sharing of information on quality at the dataset level for individual quality attribute or dimension. Although the need for assessing the quality of data and associated information is well recognized, methodologies for an evaluation framework and presentation of resultant quality information to end users may not have been comprehensively addressed within and across disciplines. Global interdisciplinary domain experts have come together to systematically explore needs, challenges and impacts of consistently curating and representing quality information through the entire lifecycle of a dataset. This paper describes the findings of that effort, argues the importance of sharing dataset quality information, calls for community action to develop practical guidelines, and outlines community recommendations for developing such guidelines. Practical guidelines will allow for global access to and harmonization of quality information at the level of individual Earth science datasets, which in turn will support open science

    The state of the Martian climate

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    60°N was +2.0°C, relative to the 1981–2010 average value (Fig. 5.1). This marks a new high for the record. The average annual surface air temperature (SAT) anomaly for 2016 for land stations north of starting in 1900, and is a significant increase over the previous highest value of +1.2°C, which was observed in 2007, 2011, and 2015. Average global annual temperatures also showed record values in 2015 and 2016. Currently, the Arctic is warming at more than twice the rate of lower latitudes
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