16,480 research outputs found

    Oxygen clamps in gold nanowires

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    We investigate how the insertion of an oxygen atom in an atomically thin gold nanowire can affect its rupture. We find, using ab initio total energy density functional theory calculations, that O atoms when inserted in gold nanowires form not only stable but also very strong bonds, in such a way that they can extract atoms from a stable tip, serving in this way as a clamp that could be used to pull a string of gold atoms.Comment: 4 pages; 4 figure

    Diluted manganese on the bond-centered site in germanium

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    The functional properties of Mn-doped Ge depend to large extent on the lattice location of the Mn impurities. Here, we present a lattice location study of implanted diluted Mn by means of electron emission channeling. Surprisingly, in addition to the expected substitutional lattice position, a large fraction of the Mn impurities occupies the bond-centered site. Corroborated by ab initio calculations, the bond-centered Mn is related to Mn-vacancy complexes. These unexpected results call for a reassessment of the theoretical studies on the electrical and magnetic behavior of Mn-doped Ge, hereby including the possible role of Mn-vacancy complexes

    Collider limits on new physics within micrOMEGAs4.3

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    Results from the LHC put severe constraints on models of new physics. This includes constraints on the Higgs sector from the precise measurement of the mass and couplings of the 125GeV Higgs boson, as well as limits from searches for other new particles. We present the procedure to use these constraints in micrOMEGAs by interfacing it to the external codes Lilith, HiggsSignals, HiggsBounds and SModelS. A few dedicated modules are also provided. With these new features, micrOMEGAs_4.3 provides a generic framework for evaluating dark matter observables together with collider and non-collider constraints.Comment: 23 page

    Desenvolvimento de Cryptolaemus montrouzieri (Coleoptera: Coccinellidae) alimentado com ovos de Ceratitis capitata (Diptera: Tephritidae).

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    O objetivo deste trabalho foi avaliar o desenvolvimento de C. montrouzieri criado em uma dieta composta apenas por ovos de C. capitata para possibilitar um método de criação desta joaninha com baixo custo, de modo a obter este inimigo natural em quantidades suficientes para utilização em programas de manejo integrado de pragas

    Effect of Insecticides Sprayed on Leaves and Applied via Soil to Aphis illinoisensis Shimer, 1866 (Hemiptera: Aphididae) on Grapevines

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    High infestations by the grapevine aphid Aphis illinoisensis (Hemiptera: Aphididae) have been observedin vineyards in southern Brazil, retarding plant growth and causing premature berry drop. This studyevaluated the effect of insecticides on the control of the species in two experiments carried out in agreenhouse. The first control experiment for A. illinoisensis was conducted with seedlings of Vitis viniferavar. ‘Cabernet Franc’ to assess the effect of azadirachtin (Azamax®) at dosages of 2.4 and 3.6 mL a.i.(active ingredient)/100 L of water, with reapplication seven days after the first application (DAFA). Tocompare its effect, the neonicotinoids imidacloprid (Provado 200 SC®) and thiamethoxam (Actara 250WG®) were sprayed at dosages of 8 mL or g a.i./100 L of water in foliar application without reapplication.The second experiment compared the effect on A. illinoisensis by spraying these neonicotinoids at dosagesof 8 mL or g a.i./100 L in foliar applications and of 0.05 mL or g a.i./100 L applied in the soil. Evaluationswere performed at 0, 1, 5, 7, 10 and 14 DAFA. Imidacloprid and thiamethoxam effectively controlled A.illinoisensis in both forms of application [soil and foliar], while azadirachtin at the dosage of 3.6 ml a.i./100L reapplied seven days after the first application provided 55.7% control. In conclusion, A. illinoisensis canbe controlled effectively by employing neonicotinoids in the soil, while azadirachtin can be an alternativeto reduce infestation pressure

    Some non genetic effects on pre and pos-weaning weights of Canchim calves.

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    Some non genetic effects on pre and pos-weaning weights of Canchim calves

    Effective Monopoles within Thick Branes

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    The monopole mass is revealed to be considerably modified in the thick braneworld paradigm, and depends on the position of the monopole in the brane as well. Accordingly, the monopole radius continuously increases, leading to an unacceptable setting that can be circumvented when the brane thickness has an upper limit. Despite such peculiar behavior, the quantum corrections accrued -- involving the classical monopole solution -- are shown to be still under control. We analyze the monopole's peculiarities also taking into account the localization of the gauge fields. Furthermore, some additional analysis in the thick braneworld context and the similar behavior evinced by the topological string are investigated.Comment: 7 pages, 1 figur
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