47,699 research outputs found

    Seasonal and Vertical Distributions of Planthoppers (Homoptera: Fulgoroidea) Within a Black Walnut Plantation

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    Information on the seasonal and vertical distributions of 34 species (eight families) of planthoppers was obtained from window trap collections in a North Carolina black walnut plantation in 15 and 1978. The most commonly collected species were Acanalonia conica (Acanaloniidael. Liburniella ornata (Delphacidae), Oliarus ecologus (Cixiidae), and O. quinquelineatus

    Nectria galligena as the cause of a collar rot disease in organically grown Topaz apple trees

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    Symptoms resembling collar rot were detected in organically managed Topaz trees aged 3-10 years, occur-ring one to several years after planting of the orchard. Trees were killed within the same growing season in which symptoms were first observed. The disease commonly progressed as a complete covered canker at the base of the tree trunk. Isolation attempts were negative for Phytophthora and other Oomycetes, but con-sistently yielded Nectria galligena. The possibility of latent (endophytic) infections of N. galligena as the cause of delayed collar rot symptoms is briefly discussed

    Diplodia seriata, cause of black fruit rot in organically grown apples in Holland, Belgium and Northern Germany

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    A fruit rot resembling Gloeosporium infections but appearing on fruits prior to harvest was noticed in organic apple orchards in Holland, Belgium and Northern Germany in 2007. Infections were most commonly observed on ‘Elstar’, but other cultivars were also affected. Fruit colonisation progressed in two steps, whereby a latent stage of sunken black lesions in immature fruits gave rise to a rapidly spreading firm brown rot upon fruit ripening. Isolation experiments from both stages consistently yielded a single species of fungus identified as Diplodia seriata, formerly known under the teleomorph name Botryosphaeria obtusa. Lesions of D. seriata were also seen on leaves as necrotic light brown spots surrounded by a purple halo, and occasionally on small twigs as cankers. Fruit mummies on apple twigs were heavily colonised by D. seriata and are thus likely to carry inoculum for fruit infections during late summer or in the following growing season

    Study to investigate and evaluate means of optimizing the Ku-band combined radar/communication functions for the space shuttle

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    The performance of the space shuttle orbiter's Ku-Band integrated radar and communications equipment is analyzed for the radar mode of operation. The block diagram of the rendezvous radar subsystem is described. Power budgets for passive target detection are calculated, based on the estimated values of system losses. Requirements for processing of radar signals in the search and track modes are examined. Time multiplexed, single-channel, angle tracking of passive scintillating targets is analyzed. Radar performance in the presence of main lobe ground clutter is considered and candidate techniques for clutter suppression are discussed. Principal system parameter drivers are examined for the case of stationkeeping at ranges comparable to target dimension. Candidate ranging waveforms for short range operation are analyzed and compared. The logarithmic error discriminant utilized for range, range rate and angle tracking is formulated and applied to the quantitative analysis of radar subsystem tracking loops

    Z Pole Observables in the MSSM

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    We present the currently most accurate prediction of Z pole observables such as sin^2 theta_eff, Gamma_Z, R_b, R_l, and sigma^0_had in the Minimal Supersymmetric Standard Model (MSSM). We take into account the complete one-loop results including the full complex phase dependence, all available MSSM two-loop corrections as well as the full SM results. We furthermore include higher-order corrections in the MSSM Higgs boson sector, entering via virtual Higgs boson contributions. For Gamma(Z -> neutralino{1} neutralino{1}) we present a full one-loop calculation. We analyse the impact of the different sectors of the MSSM with particular emphasis on the effects of the complex phases. The predictions for the Z boson observables and M_W are compared with the current experimental values. Furthermore we provide an estimate of the remaining higher-order uncertainties in the prediction of sin^2 theta_eff.Comment: 53 pages, 20 figures, journal versio

    COPTRAN - A method of optimum communication systems design

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    Single set of mathematical expressions describes system cost and probability of error of data transmission in terms of four basic parameters in the link equation. A Lagrange multiplier sets up equations whose solutions yield the optimum values for system design considerations and weight and cost values
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