8,297 research outputs found

    \u3ci\u3eAgonopterix Alstroemeriana\u3c/i\u3e (Oecophoridae) and Other Lepidopteran Associates of Poison Hemlock \u3ci\u3e(Conium Maculatum)\u3c/i\u3e in East Central Illinois

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    Poison hemlock (Conium maculatum) (Apiaceae), a noxious Eurasian weed extensively naturalized throughout North America, is characteristically attacked by few insects. Over the past two decades, an introduced oecophorid caterpillar, Agonopterix alstroemeriana, has been reported infesting poison hemlock, its sole host in its area of indigeneity, in parts of the northeastern and western United States. We report for the first time evidence of established midwestern populations of this species. We also report poison hemlock as a host plant for the polyphagous lepidopterans Eupithecia miserulata, Trichoplusia ni, and Spilosoma virginica

    Pathology in Practice

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    Payload Operations Control Center (POCC)

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    The Spacelab payload operations control center (POCC) timeline analysis program which is used to provide POCC activity and resource information as a function of mission time is described. This program is fully automated and interactive, and is equipped with tutorial displays. The tutorial displays are sufficiently detailed for use by a program analyst having no computer experience. The POCC timeline analysis program is designed to operate on the VAX/VMS version V2.1 computer system

    Forecasting Crop Basis Using Historical Averages Supplemented with Current Market Information

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    This research compares practical methods of forecasting basis, using current market information for wheat, soybeans, corn, and milo (grain sorghum) in Kansas. Though generally not statistically superior, an historical one-year average was optimal for corn, milo, and soybean harvest and post-harvest basis forecasts. A one-year average was also best for wheat post-harvest basis forecasts, whereas a five-year average was the best method for forecasting wheat harvest basis. Incorporating current market information, defined as basis deviation from historical average, improved the accuracy of post-harvest basis forecasts. A naive forecast incorporating current information was often the most accurate for post-harvest basis forecasts.basis forecast, crop basis, current information, naive forecast, Marketing,

    INCORPORATING CURRENT INFORMATION INTO HISTORICAL-AVERAGE-BASED FORECASTS TO IMPROVE CROP PRICE BASIS FORECASTS

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    Being able to accurately predict basis is critical for making marketing and management decisions. Basis forecasts can be used along with futures prices to provide cash price projections. Additionally, basis forecasts are needed to evaluate hedging opportunities. Many studies have examined factors affecting basis but few have explicitly examined the ability to forecast basis. Studies have shown basis forecasts based on simple historical averages compare favorably with more complex forecasting models. However, these studies typically have considered only a 3-year historical average for forecasting basis. This research compares practical methods of forecasting basis for wheat, soybeans, corn, and milo (grain sorghum) in Kansas. Across most of the multiple-year forecast methods considered, absolute basis forecast errors were slightly higher for the harvest forecasts than the post-harvest forecasts. Using an historical 3-year average to forecast basis for wheat and soybeans was optimal as compared to other multiple-year forecasts. For corn and milo, a 2-year average was the optimal multiple-year forecast method. Incorporating current market information, such as current nearby basis deviation from an historical average, into a harvest basis forecast improves accuracy for only the 4 weeks ahead of harvest vantage point, but improves the accuracy of post-harvest basis forecasts (24 weeks after harvest) from nearly all vantage points considered.Marketing,

    Agent-Based Team Aiding in a Time Critical Task

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    In this paper we evaluate the effectiveness of agent-based aiding in support of a time-critical team-planning task for teams of both humans and heterogeneous software agents. The team task consists of human subjects playing the role of military commanders and cooperatively planning to move their respective units to a common rendezvous point, given time and resource constraints. The objective of the experiment was to compare the effectiveness of agent-based aiding for individual and team tasks as opposed to the baseline condition of manual route planning. There were two experimental conditions: the Aided condition, where a Route Planning Agent (RPA) finds a least cost plan between the start and rendezvous points for a given composition of force units; and the Baseline condition, where the commanders determine initial routes manually, and receive basic feedback about the route. We demonstrate that the Aided condition provides significantly better assistance for individual route planning and team-based re-planning

    Intermittent fluctuations in the Alcator C-Mod scrape-off layer for ohmic and high confinement mode plasmas

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    Plasma fluctuations in the scrape-off layer of the Alcator C-Mod tokamak in ohmic and high confinement modes have been analyzed using gas puff imaging data. In all cases investigated, the time series of emission from a single spatially-resolved view into the gas puff are dominated by large-amplitude bursts, attributed to blob-like filament structures moving radially outwards and poloidally. There is a remarkable similarity of the fluctuation statistics in ohmic plasmas and in edge localized mode-free and enhanced D-alpha high confinement mode plasmas. Conditionally averaged wave forms have a two-sided exponential shape with comparable temporal scales and asymmetry, while the burst amplitudes and the waiting times between them are exponentially distributed. The probability density functions and the frequency power spectral densities are self-similar for all these confinement modes. These results are strong evidence in support of a stochastic model describing the plasma fluctuations in the scrape-off layer as a super-position of uncorrelated exponential pulses. Predictions of this model are in excellent agreement with experimental measurements in both ohmic and high confinement mode plasmas. The stochastic model thus provides a valuable tool for predicting fluctuation-induced plasma-wall interactions in magnetically confined fusion plasmas.Comment: 17 pages, 10 figure

    Nature Versus Nurture: Luminous Blue Variable Nebulae in and near Massive Stellar Clusters at the Galactic Center

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    Three Luminous Blue Variables (LBVs) are located in and near the Quintuplet Cluster at the Galactic Center: the Pistol star, G0.120-0.048, and qF362. We present imaging at 19, 25, 31, and 37 {\mu}m of the region containing these three LBVs, obtained with SOFIA using FORCAST. We argue that the Pistol and G0.120-0.048 are identical ``twins" that exhibit contrasting nebulae due to the external influence of their different environments. Our images reveal the asymmetric, compressed shell of hot dust surrounding the Pistol Star and provide the first detection of the thermal emission from the symmetric, hot dust envelope surrounding G0.120-0.048. Dust and gas composing the Pistol nebula are primarily heated and ionized by the nearby Quintuplet Cluster stars. The northern region of the Pistol nebula is decelerated due to the interaction with the high-velocity (2000 km/s) winds from adjacent Wolf-Rayet Carbon (WC) stars. With the DustEM code we determine that the Pistol nebula is composed of a distribution of very small, transiently-heated grains (10-~35 {\AA}) and that it exhibits a gradient of decreasing grain size from the south to the north due to differential sputtering by the winds from the WC stars. Dust in the G0.120-0.048 nebula is primarily heated by the central star; however, the nebular gas is ionized externally by the Arches Cluster. Unlike the Pistol nebula, the G0.120-0.048 nebula is freely expanding into the surrounding medium. Given independent dust and gas mass estimates we find that the Pistol and G0.120-0.048 nebulae exhibit similar gas-to-dust mass ratios of ~310 and ~290, respectively. Both nebulae share identical size scales (~ 0.7 pc) which suggests that they have similar dynamical timescales of ~10^5 yrs, assuming a shell expansion velocity of v_exp 60 km/s.Comment: 18 pages, 7 figures, accepted to Ap
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