898 research outputs found

    Configuration design studies and wind tunnel tests of an energy efficient transport with a high-aspect-ratio supercritical wing

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    The results of design studies and wind tunnel tests of high aspect ratio supercritical wings suitable for a medium range, narrow body transport aircraft flying near M=0.80 were presented. The basic characteristics of the wing design were derived from system studies of advanced transport aircraft where detailed structural and aerodynamic tradeoffs were used to determine the most optimum design from the standpoint of fuel usage and direct operating cost. These basic characteristics included wing area, aspect ratio, average thickness, and sweep. The detailed wing design was accomplished through application of previous test results and advanced computational transonic flow procedures. In addition to the basic wing/body development, considerable attention was directed to nacelle/plyon location effects, horizontal tail effects, and boundary layer transition effects. Results of these tests showed that the basic cruise performance objectives were met or exceeded

    Population spread of the introduced red imported fire ant parasitoid, Pseudacteon tricuspis Borgmeier (Diptera: Phoridae), in Louisiana

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    Predicting the spread of introduced species, such as natural enemies used in classical biological control programs, requires quantitative data on the rates of spread. Here, the pattern of spread of Pseudacteon tricuspis Borgmeier (Diptera: Phoridae), a parasitoid of the red imported fire ant (Solenopsis invicta Buren; Hymenoptera: Formicidae), was monitored at two widely separated release sites in Louisiana, USA. At both sites, P. tricuspis range expansion (measured as the mean radius of the range from four cardinal directions) was accelerating during the first four years post-release. This pattern contrasts with a linear pattern expected with simple diffusion. This suggests that population spread involved both a neighborhood diffusion and long-distance dispersal component. This is known as stratified or jump dispersal. Annual rates of spread were low in the first two years post-release (possibly owing to an Allee effect), increased rapidly in years 3-4, and slowed down or leveled off by years 5-6. Annual spread rates reached a peak of 15-25 km/yr, with the northward spread being about 40% greater than the spread in the other cardinal directions. High rates of spread in the latter years and directional bias in the spread of P. tricuspis may have been driven by prevailing winds and two northward-moving hurricanes. Spread of introduced species offers insight into factors affecting spread that is more difficult to evaluate for native species. © 2007 Elsevier Inc. All rights reserved

    Alpine Glacier Reveals Ecosystem Impacts of Europe’s Prosperity and Peril Over the Last Millennium

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    Information about past ecosystem dynamics and human activities is stored in the ice of Colle Gnifetti glacier in the Swiss Alps. Adverse climatic intervals incurred crop failures and famines and triggered reestablishment of forest vegetation but also societal resilience through innovation. Historical documents and lake sediments record these changes at local—regional scales but often struggle to comprehensively document continental-scale impacts on ecosystems. Here, we provide unique multiproxy evidence of broad-scale ecosystem, land use, and climate dynamics over the past millennium from a Colle Gnifetti microfossil and oxygen isotope record. Microfossil data indicate that before 1750 CE forests and fallow land rapidly replaced crop cultivation during historically documented societal crises caused by climate shifts and epidemics. Subsequently, with technology and the introduction of more resilient crops, European societies adapted to the Little Ice Age cold period, but resource overexploitation and industrialization led to new regional to global-scale environmental challenges

    Mdm1/Snx13 is a novel ER-endolysosomal interorganelle tethering protein

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    Although endolysosomal trafficking is well defined, how it is regulated and coordinates with cellular metabolism is unclear. To identify genes governing endolysosomal dynamics, we conducted a global fluorescence-based screen to reveal endomembrane effector genes. Screening implicated Phox (PX) domain-containing protein Mdm1 in endomembrane dynamics. Surprisingly, we demonstrate that Mdm1 is a novel interorganelle tethering protein that localizes to endoplasmic reticulum (ER)-vacuole/lysosome membrane contact sites (MCSs). We show that Mdm1 is ER anchored and contacts the vacuole surface in trans via its lipid-binding PX domain. Strikingly, overexpression of Mdm1 induced ER-vacuole hypertethering, underscoring its role as an interorganelle tether. We also show that Mdm1 and its paralogue Ydr179w-a (named Nvj3 in this study) localize to ER-vacuole MCSs independently of established tether Nvj1. Finally, we find that Mdm1 truncations analogous to neurological disease-associated SNX14 alleles fail to tether the ER and vacuole and perturb sphingolipid metabolism. Our work suggests that human Mdm1 homologues may play previously unappreciated roles in interorganelle communication and lipid metabolism

    Compilation of Selected Vegetable Crop Reports Dealing with Research and Demonstration Plots Located at the Muck Crops Branch, 1983

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    Spinach cultivar trials, 1982 ; Celery cultivar trials, 1982 / James M. Pisarczyk and Richard L. Hassell -- Potato cultivar trials, 1982 / James M. Pisarczyk -- Celery transplant study, 1982 / Richard L. Hassell -- Parsley 1982 variety trials ; Onion 1982 variety trials ; Broccoli variety trials, 1982 / Richard L. Hassell -- Carrot variety trials, 1982 / R. Mack Riedel and Richard C. Henne -- Control of early blight of celery with fungicides, 1982 ; Control of crucifer downy mildew with fungicide sprays, 1982 / Randall C. Rowe and Richard L. Hassell -- Synergistic interaction between species of lesion nematodes and Verticillium dahliae, 1982 / R. M. Riedel and R. C. Rowe -- Transplants vs. bare-root in controlling root-knot nematode / R. M. Riedel -- Rotations for control of root-knot nematode / R. M. Riedel and J. A. Chatfield -- Fertilizer guidelines for vegetable crops grown on muck soils in Ohio / William M. Brooks, E. C. Wittmeyer and Richard Hassel
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