53,623 research outputs found

    Presence of the “Threatened” \u3ci\u3eTrimerotropis Huroniana\u3c/i\u3e (Orthoptera: Acrididae) in Relation to the Occurrence of Native Dune Plant Species and the Exotic \u3ci\u3eCentaurea Biebersteinii\u3c/i\u3e

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    Trimerotropis huroniana Wlk. is a “Threatened” species in Michigan and Wisconsin with a distribution limited to open dune systems in the northern Great Lakes region of North America. Pitfall traps were utilized in the Grand Sable Dunes of Pictured Rocks National Lakeshore, MI, along with an herbaceous plant survey, to identify the relationship of T. huroniana with native dune plant species, Ammophila breviligulata Fern. (American beachgrass, Poaceae), Artemisia campestris L. (field sagewort, Asteraceae), and the exotic invasive plant Centaurea biebersteinii DC. [=Centaurea maculosa, spotted knapweed, Lamarck] (Asteraceae). The absence of C. biebersteinii resulted in an increased likelihood of capturing T. huroniana. This was most likely due to the increased likelihood of encountering A. campestris in areas without C. biebersteinii. The occurrence of A. breviligulata was independent of C. biebersteinii presence. A significant positive linear relationship occurred between the percent cover of A. campestris and the traps that captured T. huroniana. There was no significant relationship between A. breviligulata percent cover and the traps that captured T. huroniana. The occurrence and distribution of T. huroniana is closely related to the presence and abundance of A. campestris. Habitat conservation and improvement for T. huroniana should include increases in A. campestris populations through the removal of C. biebersteinii

    Object oriented studies into artificial space debris

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    A prototype simulation is being developed under contract to the Royal Aerospace Establishment (RAE), Farnborough, England, to assist in the discrimination of artificial space objects/debris. The methodology undertaken has been to link Object Oriented programming, intelligent knowledge based system (IKBS) techniques and advanced computer technology with numeric analysis to provide a graphical, symbolic simulation. The objective is to provide an additional layer of understanding on top of conventional classification methods. Use is being made of object and rule based knowledge representation, multiple reasoning, truth maintenance and uncertainty. Software tools being used include Knowledge Engineering Environment (KEE) and SymTactics for knowledge representation. Hooks are being developed within the SymTactics framework to incorporate mathematical models describing orbital motion and fragmentation. Penetration and structural analysis can also be incorporated. SymTactics is an Object Oriented discrete event simulation tool built as a domain specific extension to the KEE environment. The tool provides facilities for building, debugging and monitoring dynamic (military) simulations

    Predicting Emerald Ash Borer, \u3ci\u3eAgrilus Planipennis\u3c/i\u3e (Coleoptera: Buprestidae), Landing Behavior on Unwounded Ash

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    Detection of emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), an invasive forest pest, is difficult in low density populations war- ranting continual development of various trapping techniques and protocols. Understanding and predicting landing behavior of A. planipennis may assist in the further development of trapping techniques and improvement of trapping protocols for widespread survey programs in North America. Three multiple regression models were developed using ash tree vigor and crown light exposure to predict the landing behavior of A. planipennis. These models were then used to predict the landing density of A. planipennis at separate sites and in separate years. Successful prediction of A. planipennis capture density at the test sites was limited. Even though the multiple regression models were not effective at predicting landing behavior of A. planipennis, tree characteristics were used to predict the likelihood of A. planipennis landing. Trees predicted as having high likelihood of landing had 3.5 times as many A. planipennis adults/m2 on stem traps than trees predicted as having low likelihood of landing. While the landing density of A. planipennis may not be efficiently predicted, the utility of these predictions may be in the form of identifying trees with a high likelihood of A. planipennis landing. Those high likelihood trees may assist in improving existing detection programs and techniques in North American forests

    Inverse Medea as a Novel Gene Drive System for Local Population Replacement: A Theoretical Analysis

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    One strategy to control mosquito-borne diseases, such as malaria and dengue fever, on a regional scale is to use gene drive systems to spread disease-refractory genes into wild mosquito populations. The development of a synthetic Medea element that has been shown to drive population replacement in laboratory Drosophila populations has provided encouragement for this strategy but has also been greeted with caution over the concern that transgenes may spread into countries without their consent. Here, we propose a novel gene drive system, inverse Medea, which is strong enough to bring about local population replacement but is unable to establish itself beyond an isolated release site. The system consists of 2 genetic components—a zygotic toxin and maternal antidote—which render heterozygous offspring of wild-type mothers unviable. Through population genetic analysis, we show that inverse Medea will only spread when it represents a majority of the alleles in a population. The element is best located on an autosome and will spread to fixation provided any associated fitness costs are dominant and to very high frequency otherwise. We suggest molecular tools that could be used to build the inverse Medea system and discuss its utility for a confined release of transgenic mosquitoes

    Performance of Particle Flow Calorimetry at CLIC

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    The particle flow approach to calorimetry can provide unprecedented jet energy resolution at a future high energy collider, such as the International Linear Collider (ILC). However, the use of particle flow calorimetry at the proposed multi-TeV Compact Linear Collider (CLIC) poses a number of significant new challenges. At higher jet energies, detector occupancies increase, and it becomes increasingly difficult to resolve energy deposits from individual particles. The experimental conditions at CLIC are also significantly more challenging than those at previous electron-positron colliders, with increased levels of beam-induced backgrounds combined with a bunch spacing of only 0.5 ns. This paper describes the modifications made to the PandoraPFA particle flow algorithm to improve the jet energy reconstruction for jet energies above 250 GeV. It then introduces a combination of timing and p_T cuts that can be applied to reconstructed particles in order to significantly reduce the background. A systematic study is performed to understand the dependence of the jet energy resolution on the jet energy and angle, and the physics performance is assessed via a study of the energy and mass resolution of W and Z particles in the presence of background at CLIC. Finally, the missing transverse momentum resolution is presented, and the fake missing momentum is quantified. The results presented in this paper demonstrate that high granularity particle flow calorimetry leads to a robust and high resolution reconstruction of jet energies and di-jet masses at CLIC.Comment: 14 pages, 11 figure

    Spatial characterization of acid rain stress in Canadian Shield Lakes

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    The lake acidification in Northern Ontario was investigated using LANDSAT TM to sense lake volume reflectance and also to provide important vegetation and terrain characteristics. The purpose of this project was to determine the ability of LANDSAT to assess water quality characteristics associated with lake acidification. Results demonstrate that a remote sensor can discriminate lake clarity based upon reflection. The basic hypothesis is that seasonal and multi-year changes in lake optical transparency are indicative of sensitivity to acidic deposition. In many acid-sensitive lakes optical transparency is controlled by the amount of dissolved organic carbon present. Seasonal changes in the optical transparency of lakes can potentially provide an indication of the stress due to acid deposition and loading

    Resolving an Individual One-Proton Spin Flip to Determine a Proton Spin State

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    Previous measurements with a single trapped proton or antiproton detected spin resonance from the increased scatter of frequency measurements caused by many spin flips. Here a measured correlation confirms that individual spin transitions and states are detected instead. The high fidelity suggests that it may be possible to use quantum jump spectroscopy to measure the p and \pbar magnetic moments much more precisely.Comment: 4 pages, 7 figure
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