481 research outputs found

    The potential use of lures for thrips biological control in greenhouses: practice and theory

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    Exploiting the response of thrips pest species to odours has long been a goal for improving thrips pest management including biological control. Applications of attractants could include improved monitoring, push-pull (in conjunction with a repellent odour), lure and kill, and lure and infect technologies, and surveillance for invasive organisms. We have recently discovered that 4-pyridyl carbonyl compounds can elicit responses from a range of thrips species (Thrips tabaci, T. major, T. obscuratus and Frankliniella occidentalis) in the laboratory, in glasshouses and in open field bioassays. Some of these compounds can increase the trap capture of these thrips species in both commercial greenhouses and broad acre commercial crops where these species are considered pests. However, our understanding of the mechanisms eliciting this response in thrips is still only rudimentary. Greater knowledge of the underlying behavioural mechanisms, including the intrinsic and extrinsic factors that may affect these responses, as well as optimal trap design and configuration, and odour formulation, will be essential if semiochemical-based approaches are to be integrated into thrips management programme

    Hybrid gap plasmon GaAs nanolasers

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    Compact semiconductor lasers with sub-wavelength-scale dimensions rely heavily on materials with low surface recombination due to the large surface area to volume ratios of their nano-cavities. Furthermore, the reliance on semiconductor nanostructures has led to predominantly bottom-up fabrication approaches, which has hindered scalable and practical applications. In this letter, we present lithographically constructed hybrid gap plasmon nanolasers using the gain of bulk GaAs operating at room temperature. The nanolasers are built on GaAs suspended membranes with InGaP passivation layers. Laser resonators are defined only by patterning gold on top of these GaAs membranes, thus eliminating the need to etch the semiconductor for optical confinement, which would intro duce additional surface recombination. An analysis of the modal gain and losses in these devices suggests that threshold carrier densities in the range of 4-5×1018 cm -3 are necessary - potentially achievable with current densities as low as 6-8 kA cm-2

    SU(2) Yang-Mills Theory with extended Supersymmetry in a Background Magnetic Field

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    The vacuum structure of N=2 (and N=4) SUSY Yang-Mills theory is analyzed in detail by considering the effective potential for constant background scalar- magnetic fields within different approximations. We compare the one-loop approximation with- or without instanton improved effective coupling with the one-loop result in the dual desription. For N=2 we find that non-perturbative monopole degrees of freedom remove the non-trivial minima present in the (improved) one-loop potential in the strong-coupling regime. The combination of Yang-Mills and dual desription leads to a self-consistent effective potential over the full range of background fields.Comment: 15 pages, Revtex, 3 figures, References added, section two shortened, some minor remarks and corrections adde

    Demonstrating various quantum effects with two entangled laser beams

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    We report on the preparation of entangled two mode squeezed states of yet unseen quality. Based on a measurement of the covariance matrix we found a violation of the Reid and Drummond EPR-criterion at a value of only 0.36\pm0.03 compared to the threshold of 1. Furthermore, quantum state tomography was used to extract a single photon Fock state solely based on homodyne detection, demonstrating the strong quantum features of this pair of laser-beams. The probability for a single photon in this ensemble measurement exceeded 2/3

    Passiflora fissurosa, uma nova espécie de Passifloraceae para o Amazonas, Brasil

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    Passiflora fissurosa M.A.D.Souza sp. nov., atĂ© o momento conhecida apenas da Reserva Florestal Adolpho Ducke, no Amazonas, Brasil, Ă© descrita e ilustrada. Foi inserida no SubgĂȘnero Passiflora, Superseção Passiflora, Seção Laurifoliae e SĂ©rie Laurifoliae, por apresentar folhas simples e inteiras, pecĂ­olo biglandular, brĂĄcteas foliĂĄceas, livres, maiores que 1 cm, pertencendo ao grupo de espĂ©cies com as duas sĂ©ries externas da corona subiguais. Morfologicamente Ă© semelhante a P. nitida, que difere pelo opĂ©rculo horizontal-encurvado com margem ereto-divergente, anel nectarĂ­fero presente, lĂ­men vertical e ovĂĄrio glabro. A designação do epĂ­teto deve-se Ă  caracterĂ­stica do ritidoma, suberoso e profundamente fissurado, caracterĂ­stica somente encontrada em P. phellos, tambĂ©m pertencente Ă  SĂ©rie Laurifoliae, mas do grupo de espĂ©cies com a primeira sĂ©rie da corona menor que a segunda.Passiflora fissurosa M.A.D. Souza sp. nov., presently known only from the Adolpho Ducke Forest Reserve in Amazonian Brazil, is described and illustrated. P. fissurosa belongs in the subgenus Passiflora, Supersection Passiflora, Section Laurifoliae and Series Laurifoliae, with simple, entire leaves, a biglandular petiole, free foliaceous stipules larger than 1 cm, in the group of species with the outer two series of the corona sub-equal. Morphologically it resembles P. nitida, which differs by the horizontal curved with erect-divergent margin operculum, the presence of a nectariferous ring, vertical limen and glabrous ovary. The epithet is derived from the characteristic of the bark, which is corky and profoundly fissured, which is showed only by P. phellos of the Laurifoliae group which has the first series of the corona smaller than the second

    Quantum walks: a comprehensive review

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    Quantum walks, the quantum mechanical counterpart of classical random walks, is an advanced tool for building quantum algorithms that has been recently shown to constitute a universal model of quantum computation. Quantum walks is now a solid field of research of quantum computation full of exciting open problems for physicists, computer scientists, mathematicians and engineers. In this paper we review theoretical advances on the foundations of both discrete- and continuous-time quantum walks, together with the role that randomness plays in quantum walks, the connections between the mathematical models of coined discrete quantum walks and continuous quantum walks, the quantumness of quantum walks, a summary of papers published on discrete quantum walks and entanglement as well as a succinct review of experimental proposals and realizations of discrete-time quantum walks. Furthermore, we have reviewed several algorithms based on both discrete- and continuous-time quantum walks as well as a most important result: the computational universality of both continuous- and discrete- time quantum walks.Comment: Paper accepted for publication in Quantum Information Processing Journa

    Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

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    A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

    Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment

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    This paper describes an analysis of the angular distribution of W->enu and W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with the ATLAS detector at the LHC in 2010, corresponding to an integrated luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and the missing transverse energy, the W decay angular distribution projected onto the transverse plane is obtained and analysed in terms of helicity fractions f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw > 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour, are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017 +/- 0.030, where the first uncertainties are statistical, and the second include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables, revised author list, matches European Journal of Physics C versio
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