11,289 research outputs found

    Indigenous and introduced species of the Bemisia tabaci complex in sweet potato crops from Argentina

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    La batata (Ipomoea batatas (L.) Lam) es uno de los cultivos más importantes en el mundo. Recientemente se observó una severa sintomatología viral en cultivos de la región pampeana argentina, en la que están identificados begomovirus y crinivirus, ambos transmitidos exclusivamente por mosca blanca. El objetivo de este estudio fue identificar las especies de B. tabaci en cultivos de batata en Colonia Caroya, mediante el análisis de secuencias mitocondriales de la citocromo oxidasa subunidad I (mtCOI). Se identificaron dos haplotipos (especies crípticas) ya descriptos en el mundo: New World2 (especie nativa) y MEAM1 (especie introducida). Los resultados indican la presencia de ambas especies, las cuales son potenciales vectores de begomovirus y crinivirus en batata en Argentina.Sweet potato (Ipomoea batatas (L.) Lam) is one of the most important crops worldwide. Recently, the appearance of severe viral symptoms has been observed in sweet potato crops in the pampas region of Argentina and both begomovirus and crinivirus, exclusively transmitted by whiteflies, have been identified. The aim of this study was to identify B. tabaci species from sweet potato crops in Colonia Caroya by analysing mitochondrial cytochrome c oxidase subunit I (mtCOI) sequences. Two previously described haplotypes were identified: New World2 (indigenous species) and MEAM1 (introduced species). The results indicate the presence of both species, which are potential vectors of begomovirus and crinivirus in Argentina.Fil: Alemandri, V.. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Patología Vegetal; ArgentinaFil: Martino, Julia Andrea. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Patología Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Di Feo, Liliana del Valle. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Patología Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Truol, G.. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Patología Vegetal; Argentin

    On q-Deformed Supersymmetric Classical Mechanical Models

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    Based on the idea of quantum groups and paragrassmann variables, we presenta generalization of supersymmetric classical mechanics with a deformation parameter q=exp2πikq= \exp{\frac{2 \pi i}{k}} dealing with the k=3k =3 case. The coordinates of the qq-superspace are a commuting parameter tt and a paragrassmann variable θ\theta, where % \theta^3 = 0. The generator and covariant derivative are obtained, as well as the action for some possible superfields.Comment: No figures, 14 pages, Latex, revised versio

    On the description of non-unitary neutrino mixing

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    Neutrino oscillations are well established and the relevant parameters determined with good precision, except for the CP phase, in terms of a unitary lepton mixing matrix. Seesaw extensions of the Standard Model predict unitarity deviations due to the admixture of heavy isosinglet neutrinos. We provide a complete description of the unitarity and universality deviations in the light neutrino sector. Neutrino oscillation experiments involving electron or muon neutrinos and anti-neutrinos are fully described in terms of just three new real parameters and a new CP phase, in addition to the ones describing oscillations with unitary mixing. Using this formalism we describe the implications of non-unitarity for neutrino oscillations and summarize the model-independent constraints on heavy neutrino couplings that arise from current experiments.Comment: 28 pages, 8 figures, typos corrected, modified bounds on non-unitarity parameters, new figs 3 and

    A non-resonant dark-side solution to the solar neutrino problem

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    We re-analyse spin-flavour precession solutions to the solar neutrino problem in the light of the recent SNO CC result as well as the 1258--day Super-Kamiokande data and the upper limit on solar anti-neutrinos. In a self-consistent magneto-hydrodynamics approach the resulting scheme has only 3 effective parameters: Δm2\Delta m^2, μB\mu B_\perp and the neutrino mixing angle θ\theta. We show how a rates-only analysis for fixed μB\mu B_\perp slightly favours spin-flavour precession (SFP) solutions over oscillations (OSC). In addition to the resonant solution (RSFP for short), there is a new non-resonant solution (NRSFP) in the ``dark-side''. Both RSFP and NRSFP lead to flat recoil energy spectra in excellent agreement with the latest SuperKamiokande data. We also show that in the presence of a neutrino transition magnetic moment of 101110^{-11} Bohr magneton, a magnetic field of 80 KGauss eliminates all large mixing solutions other than the so-called LMA solution.Comment: 12 pages, 3 postscript figures, using elsart.cls. Published versio

    Classical realization of two-site Fermi-Hubbard systems

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    A classical wave optics realization of the two-site Hubbard model, describing the dynamics of interacting fermions in a double-well potential, is proposed based on light transport in evanescently-coupled optical waveguides.Comment: 4 page

    Visualization of Coherent Destruction of Tunneling in an Optical Double Well System

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    We report on a direct visualization of coherent destruction of tunneling (CDT) of light waves in a double well system which provides an optical analog of quantum CDT as originally proposed by Grossmann, Dittrich, Jung, and Hanggi [Phys. Rev. Lett. {\bf 67}, 516 (1991)]. The driven double well, realized by two periodically-curved waveguides in an Er:Yb-doped glass, is designed so that spatial light propagation exactly mimics the coherent space-time dynamics of matter waves in a driven double-well potential governed by the Schr\"{o}dinger equation. The fluorescence of Er ions is exploited to image the spatial evolution of light in the two wells, clearly demonstrating suppression of light tunneling for special ratios between frequency and amplitude of the driving field.Comment: final versio

    AE Aurigae: first detection of non-thermal X-ray emission from a bow shock produced by a runaway star

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    Runaway stars produce shocks when passing through interstellar medium at supersonic velocities. Bow shocks have been detected in the mid-infrared for several high-mass runaway stars and in radio waves for one star. Theoretical models predict the production of high-energy photons by non-thermal radiative processes in a number sufficiently large to be detected in X-rays. To date, no stellar bow shock has been detected at such energies. We present the first detection of X-ray emission from a bow shock produced by a runaway star. The star is AE Aur, which was likely expelled from its birthplace by the encounter of two massive binary systems and now is passing through the dense nebula IC 405. The X-ray emission from the bow shock is detected at 30" to the northeast of the star, coinciding with an enhancement in the density of the nebula. From the analysis of the observed X-ray spectrum of the source and our theoretical emission model, we confirm that the X-ray emission is produced mainly by inverse Compton upscattering of infrared photons from dust in the shock front.Comment: Accepted for publication in the Astrophysical Journal with number ApJ, 757, L6. Four figure
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