4,133 research outputs found

    Field applications of entomopathogenic fungi against Rhagoletis cerasi

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    Two myco-insecticides, Naturalis-L (Beauveria bassiana) and PreFeRal®WG (Paecilomyces fumosoroseus), were applied against adult R. cerasi (Diptera: Tephritidae) in two orchards in north-western Switzerland in summer 2006. Both products were applied at a concentration of 5.75x104 CFU / ml. With four applications at seven day intervals the whole flight period of R. cerasi was fully covered. During this period (5th June – 6th July) the temperature averaged 19.2°C, total precipitation was 60 mm. Under these conditions Naturalis-L significantly reduced the number of damaged fruit (efficacy: 69-74%), whereas damage was not significantly reduced with PreFeRal®WG (efficacy: 27%). Fungus infested flies were found on the yellow sticky traps proving that the myco-insecticides worked as predicted. Climatic conditions were different in 2007: temperature averaged 15.9°C (16th May – 4th July), total precipitation was 281 mm. In 2007 only Naturalis-L was tested: with five applications an efficacy of 73% and 78% was obtained on the cherry varieties Langstieler and Dolleseppler, respectively. However, for the latest ripening and most infested variety Schauenburger only an efficacy of 18% was observed. In these cherries a high number of young larvae were found indicating that the efficacy was low at the end of the treatment period. In conclusion a control of R. cerasi with myco-insecticides seems possible. However, application regime still has to be improved and should not only be adapted to the flight period of R. cerasi, but also to the cherry varieties

    Dichotomous Hamiltonians with Unbounded Entries and Solutions of Riccati Equations

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    An operator Riccati equation from systems theory is considered in the case that all entries of the associated Hamiltonian are unbounded. Using a certain dichotomy property of the Hamiltonian and its symmetry with respect to two different indefinite inner products, we prove the existence of nonnegative and nonpositive solutions of the Riccati equation. Moreover, conditions for the boundedness and uniqueness of these solutions are established.Comment: 31 pages, 3 figures; proof of uniqueness of solutions added; to appear in Journal of Evolution Equation

    LHC Arc Dipole Status Report

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    The LHC, a 7 TeV proton collider presently under construction at CERN, requires 1232 superconducting (SC) dipole magnets, featuring a nominal field of 8.33 T inside a cold beam tube of 50 mm inner diameter and a magnetic length of 14.3 m. To achieve such high fields whilst retaining the well-proven fabrication methods of cables made with NbTi superconductors, it is necessary to operate the magnets at 1.9 K in superfluid helium. For reasons of space and economy, the two dipole apertures are incorporated into a single iron yoke and cryostat (two-in-one concept). The design considerations and the experimental results, which have led to the design adopted for series manufacture, are presented and discussed. The aims and status of the short model and full size prototype dipole programmes are subsequently reported. Finally, the major milestones of the schedule of the dipole magnets series manufacture are given and commented

    The LHC Magnet Programme: From Accelerator Physics Requirements to Production in Industry

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    The LHC is designed to provide, at a beam energy of 7 TeV, a nominal peak luminosity of 1034 cm-2s-1 with simultaneous collisions at two high-luminosity insertions. This objective is being achieved by pushing the technology of superconducting accelerator magnets and cryogenics to its state-of-the-art limits, and by upgrading the existing CERN accelerators and infrastructures. In this paper, the parameters of the main dipole (1232 units) and quadrupole (392 units) magnets stemming from the LHC design considerations are presented and discussed. Subsequently, the R & D program undertaken at CERN and with industry, to experimentally validate magnet design assumptions, to assess the merits of design variants and to procure and commission the heavy tooling necessary for series manufacture, is described and its main difficulties and results highlighted. Finally a report is given about the procurement strategy, and the progress in manufacturing

    Fatty acids synthesized by oral treponemes in chemically defined media

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    OMIZ-W68, a chemically defined medium that contains no long-chain fatty acids and yet supports in vitro proliferation of a wide range of fastidious oral anaerobes, is described. The type strains of Treponema denticola, Treponema lecithinolyticum, Treponema maltophilum, Treponema pectinovorum, Treponema socranskii, and an as yet unpublished canine Treponema species could be propagated indefinitely in this medium with sugar supplements for the saccharolytic species. Analysis of the cellular fatty acids (CFA) of these treponemes by gas chromatography demonstrated the synthesis of C14, C15, C16, and C17 fatty acids (linear-, iso-, and anteiso-forms) in various proportions, but neither hydroxy- nor unsaturated fatty acids. However, between 0% and 40% of the eluted material could not be identified. The proportions of CFAs differed not only between species but also between the eight strains of Treponema denticola investigated. Replacing OMIZ-W68 by a derivative minimal essential medium (OMIZ-M/TDCDK) developed for Treponema denticola had little effect on the CFA profiles. In contrast, the CFA profiles of treponemes grown in OMIZ-W68 showed at best minor similarity to the strains from the Moore library of the Virginia Polytechnic Institute, which had been grown in media containing serum, peptones, and yeast extrac

    Potential and Limits of Pesticide Free Apple Growing by a Self-Regulating Orchard Set-Up: Project Presentation and First Experiences

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    Different research groups have already proven that flowering plants in orchards can enhance beneficial arthropods. Even within the tree rows different beneficial can be supported by selected plant species. In most experimental work done to stabilize the apple production system only single interaction effects were tested. However until now, no research group has quantified the additive effects of multiple measures on systembiodiversity and on the production economy. Our experiment combines all known measures of indirect pest and disease control measures in a near-to practical production model orchard without the use of any pesticide (not even organic ones). The orchard is split in 4 blocks: in two of them bio-control measures e.g. application of Granulosis Virus against codling moth (C. Pomonella) are applied; in the other two blocks no bio-control is applied. Standard commercial organic and integrated orchards with the disease-susceptible cultivar Gala in the vicinity of the model orchard are assessed by the same methods and serve as reference. Our intermediate results reveal that the self-regulating orchard developed already in the 2nd and 3rd leaf a clearly higher flora and fauna biodiversity compared to the reference orchards. The same happened in relation to the specific fruit beneficial e.g. the populations of aphid predators. In the self-regulating orchard they were capable to keep the aphid damages – in particular of the powdery apple aphid (D. plantaginea) - on trees and fruits under a commercially relevant level although the initial abundance of aphid colonies in spring was by far over the common threshold value. It is planned to continue the experiment until 2016

    Internationale Chemie-Olympiade

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    Prospects for energy and luminosity at LEP2

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    The use of body-wave spectra in the determination of seismic-source parameters

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    Teleseismic determinations of body-wave (P, S) spectra, interpreted in terms of the Brune (1970) seismic-source model, are used to estimate the parameters seismic moment (M_o) and source dimension (r) for three large, shallow, strike-slip earthquakes occurring on nearly vertical fault planes and for which the same parameters can be determined from field (F) data. These earthquakes are (1) the Borrego Mountain, California, earthquake (April 9, 1968) for which [M̅_o(P) = 10, M̅_o(S) = 6.6, and M_o(F) = 3.6] × 10^(25) dyne-cm and [r̅(p) = 14, r̅(S) = 23, and L/2(F) = 17] km; (2) the Mudurnu Valley, Turkey, earthquake (July 22, 1967) for which [M̅_o(P) = 9.1, M̅_o(S) = 8.5, and M_o(F) = 7.4] × 10^(26) dyne-cm, and [r̅(P) = 39, r̅(S) = 48, and L/2(F) = 40] km; and (3) the Dasht-e-Bayāz, Iran, earthquake (August 31, 1968) for which [M̅_o(P) = 4.8, M̅_o(S) = 8.6, and M_o(F) = 18] × 10^(26) dyne-cm, and [r̅(P) = S1, r̅(S) = 48, and L/2(F) = 40] km. The Brune (1970) model is well-calibrated with respect to the determination of these parameters for the earthquakes considered. A minimum estimate for the radiated energy can be expressed in terms of M_o and r; this estimate is low by a factor of 10 with respect to the estimate obtained from energy-magnitude relations for these three earthquakes. The stress drops of these events are of the order of 10 bars
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