333 research outputs found

    Quantum equivalence of sigma models related by non Abelian Duality Transformations

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    Coupling constant renormalization is investigated in 2 dimensional sigma models related by non Abelian duality transformations. In this respect it is shown that in the one loop order of perturbation theory the duals of a one parameter family of models, interpolating between the SU(2) principal model and the O(3) sigma model, exhibit the same behaviour as the original models. For the O(3) model also the two loop equivalence is investigated, and is found to be broken just like in the already known example of the principal model.Comment: As a result of the collaboration of new authors the previously overlooked gauge contribution is inserted into eq.(43) changing not so much the formulae as part of the conclusion: for the models considered non Abelian duality is OK in one loo

    Molecular phylogeny, diagnostics, and diversity of plant-parasitic nematodes of the genus Hemicycliophora (Nematoda: Hemicycliophoridae)

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    The genus Hemicycliophora (Nematoda: Hemicycliophoridae) contains 132 valid species of plant-parasitic nematodes, collectively known as ‘sheath nematodes’. Hemicycliophora spp. are characterized morphologically by a long stylet with rounded basal knobs and a cuticular sheath, present in juvenile and adult stages. Populations of 20 valid and 14 putative species of Hemicycliophora and Loofia from several countries were characterized morphologically using light (LM) and scanning electron microscopy (SEM) and molecularly using the D2-D3 segments of 28S rRNA and internal transcribed spacer (ITS) rRNA gene sequences. LM and SEM observations provided new details on the morphology of these species. PCR-restriction fragment length polymorphisms (PCR-RFLPs) of the D2-D3 of 28S rDNA were proposed for identification of the species. Phylogenetic relationships within populations of 36 species of the genus Hemicycliophora using 102 D2-D3 of 28S rDNA and 97 ITS rRNA gene sequences as inferred from Bayesian analysis are reconstructed and discussed. Ancestral state reconstructions of diagnostic characters (body and stylet length, number of body annuli, shape of vulval lip and tail), using maximum parsimony and Bayesian inference, revealed that none of the traits are individually reliable characters for classifying the studied sheath nematode. The Shimodaira–Hasegawa test rejected the validity of the genus Loofia. This is the most complete phylogenetic analysis of Hemicycliophora species conducted so far.Fil: Subbotin, Sergei A.. California Department of Food and Agriculture; Estados Unidos. Institute of Ecology and Evolution of the Russian Academy of Sciences; RusiaFil: Chitambar, John J.. California Department of Food and Agriculture; Estados UnidosFil: Chizhov, Vladimir N.. Institute of Ecology and Evolution of the Russian Academy of Sciences; RusiaFil: Stanley, Jason D.. Florida Department of Agriculture and Consumer Services; Estados UnidosFil: Inserra, Renato N.. Florida Department of Agriculture and Consumer Services; Estados UnidosFil: Doucet, Marcelo Edmundo. Universidad Nacional de Cordoba. Facultad de Cs.exactas Fisicas y Naturales. Centro de Zoologia Aplicada; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Cordoba. Instituto de Diversidad y Ecologia Animal; ArgentinaFil: Mcclure, Michael. University Of Arizona; Estados UnidosFil: Ye, Weimin. North Carolina Department of Agriculture & Consumer Services; Estados UnidosFil: Yeates, George.Fil: Mollov, Dimitre S.. University Of Minnesota; Estados UnidosFil: Cantalapiedra Navarrete, Carolina. Consejo Superior de Investigaciones Científicas. Instituto de Agricultura Sostenible; EspañaFil: Vovlas, Nicola. Istituto per la Protezione delle Piante; ItaliaFil: Van Den Berg, Esther. ARC-Plant Protection Research Institute; SudáfricaFil: Castillo, Pablo. Consejo Superior de Investigaciones Científicas. Instituto de Agricultura Sostenible; Españ

    Normal families of functions and groups of pseudoconformal diffeomorphisms of quaternion and octonion variables

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    This paper is devoted to the specific class of pseudoconformal mappings of quaternion and octonion variables. Normal families of functions are defined and investigated. Four criteria of a family being normal are proven. Then groups of pseudoconformal diffeomorphisms of quaternion and octonion manifolds are investigated. It is proven, that they are finite dimensional Lie groups for compact manifolds. Their examples are given. Many charactersitic features are found in comparison with commutative geometry over R\bf R or C\bf C.Comment: 55 pages, 53 reference

    Disappearance of plasmaspheric hiss following interplanetary shock

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    Abstract Plasmaspheric hiss is one of the important plasma waves controlling radiation belt dynamics. Its spatiotemporal distribution and generation mechanism are presently the object of active research. We here give the first report on the shock-induced disappearance of plasmaspheric hiss observed by the Van Allen Probes on 8 October 2013. This special event exhibits the dramatic variability of plasmaspheric hiss and provides a good opportunity to test its generation mechanisms. The origination of plasmaspheric hiss from plasmatrough chorus is suggested to be an appropriate prerequisite to explain this event. The shock increased the suprathermal electron fluxes, and then the enhanced Landau damping promptly prevented chorus waves from entering the plasmasphere. Subsequently, the shrinking magnetopause removed the source electrons for chorus, contributing significantly to the several-hours-long disappearance of plasmaspheric hiss

    New limits on the resonant absorption of solar axions obtained with a 169^{169}Tm-containing cryogenic detector

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    A search for resonant absorption of solar axions by 169^{169}Tm nuclei was carried out. A newly developed approach involving low-background cryogenic bolometer based on Tm3_3Al5_5O12_{12} crystal was used that allowed for significant improvement of sensitivity in comparison with previous 169^{169}Tm based experiments. The measurements performed with 8.188.18 g crystal during 6.66.6 days exposure yielded the following limits on axion couplings: gAγ(gAN0+gAN3)1.44×1014|g_{A\gamma} (g_{AN}^0 + g_{AN}^3) \leq 1.44 \times 10^{-14} GeV1^{-1} and gAe(gAN0+gAN3)2.81×1016|g_{Ae} (g_{AN}^0 + g_{AN}^3) \leq 2.81 \times 10^{-16}.Comment: 7 pages, 5 figure

    Comparing electron precipitation fluxes calculated from pitch angle diffusion coefficients to LEO satellite observations

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    Particle precipitation is a loss mechanism from the Radiation Belts whereby particles trapped by the Earth’s magnetic field are scattered into the loss cone due to wave‐particle interactions. Energetic electron precipitation creates ozone destroying chemicals which can affect the temperatures of the polar regions, therefore it is crucial to accurately quantify this impact on the Earth’s atmosphere. We use bounce‐averaged pitch angle diffusion coefficients for whistler mode chorus waves, plasmaspheric hiss and atmospheric collisions to calculate magnetic local time (MLT) dependent electron precipitation inside the field of view of the Polar Orbiting Environmental Satellites (POES) T0 detector, between 26‐30 March 2013. These diffusion coefficients are used in the BAS Radiation Belt Model (BAS‐RBM) and this paper is a first step towards testing the loss in this model via comparison with real world data. We find the best agreement between the calculated and measured T0 precipitation at L* > 5 on the dawnside for the > 30keV electron channel, consistent with precipitation driven by lower band chorus. Additional diffusion is required to explain the flux at higher energies and on the dusk side. The POES T0 detector underestimates electron precipitation as its field of view does not measure the entire loss cone. We demonstrate the potential for utilizing diffusion coefficients to reconstruct precipitating flux over the entire loss cone. Our results show that the total precipitation can exceed that measured by the POES > 30 keV electron channel by a factor that typically varies from 1 to 10 for L* = 6, 6.5 and 7

    Attempt to produce element 120 in the 244 Pu + 58 Fe reaction

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    An experiment aimed at the synthesis of isotopes of element 120 has been performed using the 244 Pu( 58 Fe,xn) 302−x 120 reaction. No decay chains consistent with fusion-evaporation reaction products were observed during an irradiation with a beam dose of 7.1 × 10 18 330-MeV 58 Fe projectiles. The sensitivity of the experiment corresponds to a cross section of 0.4 pb for the detection of one decay
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