189,713 research outputs found
PRICE DISCOVERY FOR STOCKER CATTLE FUTURES AND OPTIONS
No full textLow trading volume in the CME stocker cattle contracts has made hedgers and speculators reluctant to use the contracts. Traders need decision tools to discover prices or to evaluate quoted prices that may not contain all the information in the market. The number of head of stocker weight cattle sold on the spot market has increased in recent years while the practice of cross-hedging stocker weight cattle against the feeder cattle contract remains risky. A model explains the spread between feeder cattle and stocker cattle futures prices as a function of feed prices, live cattle prices, and seasonal factors. The volatility of spot stocker cattle prices is comparable to spot feeder cattle prices, supporting the idea of using feeder cattle implied volatility measures as estimates of stocker cattle futures implied volatility in option pricing models. The model and relations proposed should be useful for traders evaluating observed prices or placing limit orders for stocker futures and options.stocker cattle, cross-hedging, volatility, limit order, thin markets, Marketing,
ADOPTION OF BEST MANAGEMENT PRACTICES IN STOCKER CATTLE PRODUCTION
No full textThis study identifies current production and management practices of Oklahoma stocker cattle producers and analyzes factors affecting the adoption of best management practices (BMPs) using chi-square analysis. Results reveal that factors influencing the adoption of BMPs are operation size, dependency upon income from the operation, and specialization in stocker production.cattle, stockers, management, production, Livestock Production/Industries,
ENERGY SUPPLEMENTATION STRATEGIES FOR WHEAT PASTURE STOCKER CATTLE UNDER UNCERTAIN FORAGE AVAILABILITY
No full textEnergy supplementation provides a means of reducing production risk of growing stocker cattle on winter wheat pasture. This study addresses the issue of risk aversion and energy supplement input use. Differences in supplementation practices induced by risk aversion and the effects of cattle and feed market conditions are examined. Results show that supplementation practices are likely to be similar across producers, irrespective of their risk attitudes. Cattle and feed market conditions, however, markedly affect supplementation practices. These findings provide information for assisting stockmen in identifying efficient supplement strategies.Risk, Wheat pasture grazing, Numerical integration, Energy supplementation, Livestock Production/Industries,
GPP: Site-scale and global model outputs from P-model used for Stocker et al. (2019) Nature Geosci.
No full text<p><strong>Data from article Stocker et al. (in review) *Nature Geosci.*</strong></p>
<p>The datasets provided here include:</p>
<ul>
<li>Site-level GPP model results from the P-model (Wang et al., 2017)</li>
<li>Model outputs from global simulations with the P-model (Wang et al., 2017) as implemented for the study by Stocker et al. (2019)</li>
</ul>
<p>This data may be used to partly reproduce results presented in Stocker et al. (2019) <em>Nature Geosci</em>. "Partly" because we used data for our analysis that was not open access but was confidentially shared with us. This includes remote sensing-based GPP estimates from the BESS and VPM models. Other open access data that was used for the analysis may not be distributed under this DOI. This includes FLUXNET 2015 data and MODIS data.</p>
<p>For reproducing results of Stocker et al. (2019) regarding site-scale evaluations, run for example the scripts `plot_bias_all.R` and `plot_bias_problem.R`, available from <a href="https://github.com/stineb/soilm_global">Github</a> or <a href="http://doi.org/10.5281/zenodo.1423328">Zenodo</a>, using CSV files provided here (see comments in scripts). For more insight, including analysis of global simulation outputs, see RMarkdown file `si_soilm_global.Rmd`. This renders the supplementary information PDF document provided along with Stocker et al. (2019), which is available also on <a href="http://rpubs.com/stineb/si_soilm_global2">RPubs</a>.</p>
<p>The present datasets are prepared by script `prepare_data_openaccess.R ` on <a href="https://github.com/stineb/soilm_global">Github</a> or <a href="https://zenodo.org/record/1286966#.W6TFipMzbUI">Zenodo</a>.</p>
<p><strong>Data description</strong></p>
<p><em>Site-level data</em></p>
<p>Data is provided as CSV files:</p>
<ul>
<li>`gpp_daily_fluxnet_stocker18natgeo.csv`: Daily data for full time series (not including MODIS GPP)</li>
<li>`gpp_8daily_fluxnet_stocker18natgeo.csv`: Data aggregated to 8-day periods corresponding to MODIS dates (including MODIS GPP)</li>
<li>`gpp_alg_daily_fluxnet_stocker18natgeo.csv`: Data filtered to periods with substantial soil moisture effects ("fLUE droughts" following Stocker et al. (2018a))</li>
<li>`gpp_alg_8daily_fluxnet_stocker18natgeo.csv`: Data aggregated to 8-day periods and filtered to periods with substantial soil moisture effects.</li>
</ul>
<p>Each column is a variable with the following name and units (not all variables are available in all files):</p>
<ul>
<li>`site_id`: FLUXNET site ID </li>
<li>`date`: Date of measurement, units: YYYY-MM-DD</li>
<li>`gpp_pmodel` and `gpp_modis`: Simulated GPP from the P-model and MODIS (see Stocker et al. (2018b), Methods, RS models), units: g C m-2 d-1 (mean across 8 day periods in respective files)</li>
<li>`aet_splash`: Simulated actual evapotranspiration from the SPLASH model (Davis et al., 2017), units: mm d-1</li>
<li>`pet_splash`: Simulated potential evapotranspiration from the SPLASH model (Davis et al., 2017), units: mm d-1</li>
<li>`soilm_splash`: Soil moisture simulated by the SPLASH model (Davis et al., 2017), normalised to vary between zero and one at the maximum water holding capacity, unitless.</li>
<li>`flue`: fLUE estimate from Stocker et al. (2018). Estimates soil moisture stress on light use efficiency from flux data, unitless.</li>
<li>`beta_a`, `beta_b`, and `beta_c`: Empirical soil moisture stress, used as multiplier to simulated GPP as described in Stocker et al. (2018b), unitless.</li>
</ul>
<p><em>Global P-model simulation outputs</em></p>
<p>GPP and soil moisture output is provided as NetCDF files for simulations s0, and s1b (see Stocker et al. (2018b)). All meta information is provided therein. Files for simulation s1b are names as follows (for outputs from other simulations replace s1b with other simulation name). The fraction of each gridcell covered by land (not open water or ice) is given by separate file `s1b_fapar3g_v2_global.fland.nc`.</p>
<ul>
<li>`s1b_fapar3g_v2_global.d.gpp.nc`: Daily GPP from simulation s1b.</li>
<li>`s1b_fapar3g_v2_global.d.wcont.nc`: Daily soil moisture from simulation s1b (is identical in other simulations, therefore not provided.)</li>
</ul>
<p>Due to limited total file size allowed for uploads to Zenodo, only outputs from s1b are provided here. Other outputs may be obtained upon request addressed to [email protected]. </p>
<p><strong>References</strong></p>
<p>Davis, T. W. et al. Simple process-led algorithms for simulating habitats (SPLASH v.1.0): robust indices of radiation, evapotranspiration and plant-available moisture. Geoscientific Model Development 10, 689–708 (2017).<br>
Hufkens, K. khufkens/gee_subset: Google Earth Engine subset script & library. (2017). doi:10.5281/zenodo.833789Running, S. W. et al. A Continuous Satellite-Derived Measure of Global Terrestrial Primary Production. Bioscience 54, 547–560 (2004).<br>
Stocker, B. et al., Quantifying soil moisture impacts on light use efficiency across biomes, New Phytologist, doi: 10.1111/nph.15123 (2018a).<br>
Stocker, B. et al., Satellite monitoring underestimates the impact of drought on terrestrial primary productivity, Nature Geoscience (2019).<br>
Wang, H. et al. Towards a universal model for carbon dioxide uptake by plants. Nat Plants 3, 734–741 (2017).<br>
</p>
soilm_global: Code for Stocker et al. (2019) Nature Geosci.
No full text<p>Code accompanying paper Stocker et al. (2019) <em>Nature Geosci</em>. For further information, see README and si_soilm_global.Rmd.</p>
Optimal Grazing Termination Date for Dual-Purpose Winter Wheat Production
No full textDual-purpose winter wheat (fall-winter forage plus grain) production is an important economic enterprise in the southern Great Plains. Grazing termination to enable grain production is a critical decision. The objective is to determine the optimal grazing termination date for dual-purpose wheat. The value of knowing the occurrence of first hollow stem (FHS), a wheat growth threshold for grazing termination, is also determined. Results indicate that for most price situations grazing should be terminated at or before FHS. Marginal wheat returns from extended grazing were negative and the value of FHS information ranges from 10 per acre.dual-purpose, first hollow stem, plateau function, stocker cattle, value of information, wheat, Agribusiness, Agricultural Finance, Crop Production/Industries, Farm Management, Land Economics/Use, Livestock Production/Industries, Production Economics, Q12, Q16,
Developmental Regulation of Small-Conductance Ca²⁺-Activated K⁺ Channel Expression and Function in Rat Purkinje Neurons
No full textCalcium transients play an important role in the early and later phases of differentiation and maturation of single neurons and neuronal networks. Small-conductance calcium-activated potassium channels of the SK type modulate membrane excitability and are important determinants of the firing properties of central neurons. Increases in the intracellular calcium concentration activate SK channels, leading to a hyperpolarization of the membrane potential, which in turn reduces the calcium inflow into the cell. This feedback mechanism is ideally suited to regulate the spatiotemporal occurrence of calcium transients. However, the role of SK channels in neuronal development has not been addressed so far. We have concentrated on the ontogenesis and function of SK channels in the developing rat cerebellum, focusing particularly on Purkinje neurons. Electrophysiological recordings combined with specific pharmacological tools have revealed for the first time the presence of an afterhyperpolarizing current (I_{AHP}) in immature Purkinje cells in rat cerebellar slices. The channel subunits underlying this current were identified as SK2 and localized by in situ hybridization and subunit-specific antibodies. Their expression level was shown to be high at birth and subsequently to decline during the first 3 weeks of postnatal life, both at the mRNA and protein levels. This developmental regulation was tightly correlated with the expression of I_{AHP} and the prominent role of SK2 channels in shaping the spontaneous firing pattern in young, but not in adult, Purkinje neurons. These results provide the first evidence of the developmental regulation and function of SK channels in central neurons
GPP at FLUXNET Tier 1 sites from P-model
No full textGross primary production, simulated by the P-model for each FLUXNET 2015 Tier 1 site. The model was driven by site-specific meteorological forcing and MODIS FPAR, extracted for the pixel corresponding to the site location.
The CSV files contain simulated GPP values from different model setups conducted with the P-model and used for the publication Stocker et al. Geosci. Mod. Dev. (in review). One file is given for each temporal aggregation level (daily, 8-daily, annual, spatial [= mean annual value by site], and mean seasonal cycle [= mean per day-of-year]. Each file contains output from all model setups presented in Stocker et al. (2019), as given by column setup.
The data differs slightly for each file:
Daily gpp_pmodel_fluxnet2015_stocker19gmd_daily.csv:
sitename: A character specifying the site ID following the naming given by FLUXNET 2015.
date: YYYY-MM-DD), date_start (in _8daily, YYYY-MM-DD specifying the first day of the respective 8-day period), year (in _annual, YYYY), doy (in __meanseason, specifying the day-of-year),
gpp: Simulated gross primary production, in units of g C m-2 d-1
setup: A character specifying the model setup name used in Stocker et al. (2019). See also below.
8-daily gpp_pmodel_fluxnet2015_stocker19gmd_8daily.csv:
sitename: A character specifying the site ID following the naming given by FLUXNET 2015.
date_start : YYYY-MM-DD specifying the first day of the respective 8-day period
gpp: Simulated gross primary production, in units of g C m-2 d-1
setup: A character specifying the model setup name used in Stocker et al. (2019). See also below.
Annual gpp_pmodel_fluxnet2015_stocker19gmd_annual.csv:
sitename: A character specifying the site ID following the naming given by FLUXNET 2015.
year: YYYY
gpp: Simulated gross primary production, in units of g C m-2 yr-1
setup: A character specifying the model setup name used in Stocker et al. (2019). See also below.
Spatial gpp_pmodel_fluxnet2015_stocker19gmd_spatial.csv:
sitename: A character specifying the site ID following the naming given by FLUXNET 2015.
gpp: Simulated gross primary production, in units of g C m-2 yr-1
setup: A character specifying the model setup name used in Stocker et al. (2019). See also below.
Mean seasonal cycle gpp_pmodel_fluxnet2015_stocker19gmd_meanseason.csv:
sitename: A character specifying the site ID following the naming given by FLUXNET 2015.
doy: day-of-year
gpp: Simulated gross primary production, in units of g C m-2 d-1
setup: A character specifying the model setup name used in Stocker et al. (2019). See also below.
</p
George Patrick Stocker
No full textStocker standing by and looking at portrait of William Nathan Gladson. On verso: Dean G. P. Stocker. Engineering dean, 1936-48, Emeritus.George Patrick Stocker (1883-1961) was Head of the University of Arkansas Department of Civil Engineering from 1919-1948, and Dean of the College of Engineering from 1936-1948. A photograph and summary are included about Dean Stocker on page 108 in: Image and Reflection: A Pictorial History of the University of Arkansas by Ethel C. Simpson, published by the University of Arkansas Press, 1990
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