257 research outputs found

    Management of Potato Leafhopper, Empoasca fabae (Homoptera: Cicadellidae), on Alfalfa with the Aid of Systems Analysis

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    Efficient management of the potato leafhopper (Homoptera: Cicadellidae) on alfalfa requires a procedure for dealing with the complexities of the ecological and economic system. We developed a mathematical model to represent this agroecosystem and demonstrated how systems analysis can help to make management more efficient and less risky. Our management policies were based on two criteria: annual income calculated from the nutrient yields of three harvests, and level of carbohydrate reserve in the taproots at the end of the season, We determined the dynamic economic thresholds for controlling the leafhoppers as immigrants on each of the cuttings of alfalfa. During development of the thresholds we tested a variety of control tactics, including timing of harvests, We found that, for adult immigrants on the second crop, the economic thresholds increase exponentially as stem height increases, Tactics associated with these thresholds included insecticide treatments and early cutting of the second harvest. The results indicated that temperature pattern has an important effect on the economic thresholds and risk. Evaluation of the model and its results through sensitivity analysis, validation, and a comparison with current recommendations showed that the model can be a useful tool in research and managemen

    The Mineralization Front of the Eastern Oyster is Cellular

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    Abstract of Technical Paper Presented at the 101st Annual Meeting National Shellfisheries Association Savannah, Georgia March 22–26, 200

    Towards Biomimetic Ceramic Coatings: Cellular Aspects of Oyster Shell Biomineralization

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    Abstract of Technical Paper Presented at the 101st Annual Meeting National Shellfisheries Association Savannah, Georgia March 22–26, 200

    Deposition of nanocrystalline calcite on surfaces by a tissue and cellular biomineralization

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    Disclosed are articles comprising layered nanocrystalline calcite and methods for forming nanocrystalline calcite layers and compositions comprising nanocrystalline calcite layers

    Deposition of nanocrystalline calcite on surfaces by a tissue and cellular biomineralization

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    Disclosed are articles comprising layered nanocrystalline calcite and methods for forming nanocrystalline calcite layers and compositions comprising nanocrystalline calcite layers

    The Arctic Ocean Seasonal Cycles of Heat and Freshwater Fluxes: Observation-Based Inverse Estimates

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    This paper presents the first estimate of the seasonal cycle of ocean and sea ice heat and freshwater (FW) fluxes around the Arctic Ocean boundary. The ocean transports are estimated primarily using 138 moored instruments deployed in September 2005–August 2006 across the four main Arctic gateways: Davis, Fram, and Bering Straits, and the Barents Sea Opening (BSO). Sea ice transports are estimated from a sea ice assimilation product. Monthly velocity fields are calculated with a box inverse model that enforces mass and salt conservation. The volume transports in the four gateways in the period (annual mean ± 1 standard deviation) are −2.1 ± 0.7 Sv in Davis Strait, −1.1 ± 1.2 Sv in Fram Strait, 2.3 ± 1.2 Sv in the BSO, and 0.7 ± 0.7 Sv in Bering Strait (1 Sv ≡ 106 m3 s−1). The resulting ocean and sea ice heat and FW fluxes are 175 ± 48 TW and 204 ± 85 mSv, respectively. These boundary fluxes accurately represent the annual means of the relevant surface fluxes. The ocean heat transport variability derives from velocity variability in the Atlantic Water layer and temperature variability in the upper part of the water column. The ocean FW transport variability is dominated by Bering Strait velocity variability. The net water mass transformation in the Arctic entails a freshening and cooling of inflowing waters by 0.62 ± 0.23 in salinity and 3.74° ± 0.76°C in temperature, respectively, and a reduction in density by 0.23 ± 0.20 kg m−3. The boundary heat and FW fluxes provide a benchmark dataset for the validation of numerical models and atmospheric reanalysis products

    Hadron Production in Ultra-relativistic Nuclear Collisions: Quarkyonic Matter and a Triple Point in the Phase Diagram of QCD

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    We argue that features of hadron production in relativistic nuclear collisions, mainly at CERN-SPS energies, may be explained by the existence of three forms of matter: Hadronic Matter, Quarkyonic Matter, and a Quark-Gluon Plasma. We suggest that these meet at a triple point in the QCD phase diagram. Some of the features explained, both qualitatively and semi-quantitatively, include the curve for the decoupling of chemical equilibrium, along with the non-monotonic behavior of strange particle multiplicity ratios at center of mass energies near 10 GeV. If the transition(s) between the three phases are merely crossover(s), the triple point is only approximate.Comment: 28 pages, 9 figures; submitted to Nucl. Phys. A; v2 to eliminate obsolete figs. inadvertently attached at the end of the paper; v3: final version accepted for publicatio
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