333 research outputs found
Quantum equivalence of sigma models related by non Abelian Duality Transformations
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)
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
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 or .Comment: 55 pages, 53 reference
Disappearance of plasmaspheric hiss following interplanetary shock
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 Tm-containing cryogenic detector
A search for resonant absorption of solar axions by Tm nuclei was
carried out. A newly developed approach involving low-background cryogenic
bolometer based on TmAlO crystal was used that allowed for
significant improvement of sensitivity in comparison with previous Tm
based experiments. The measurements performed with g crystal during
days exposure yielded the following limits on axion couplings:
GeV and
.Comment: 7 pages, 5 figure
Comparing electron precipitation fluxes calculated from pitch angle diffusion coefficients to LEO satellite observations
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
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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Synthesis of the isotopes of elements 118 and 116 in the 249Cf and 245Cm+48Ca fusion reactions
The decay properties of {sup 290}116 and {sup 291}116, and the dependence of their production cross sections on the excitation energies of the compound nucleus, {sup 293}116, have been measured in the {sup 245}Cm({sup 48}Ca,xn){sup 293-x}116 reaction. These isotopes of element 116 are the decay daughters of element 118 isotopes, which are produced via the {sup 249}Cf+{sup 48}Ca reaction. They performed the element 118 experiment at two projectile energies, corresponding to {sup 297}118 compound nucleus excitation energies of E* = 29.2 {+-} 2.5 and 34.4 {+-} 2.3 MeV. During an irradiation with a total beam dose of 4.1 x 10{sup 19} {sup 48}Ca projectiles, three similar decay chains consisting of two or three consecutive {alpha} decays and terminated by a spontaneous fission (SF) with high total kinetic energy of about 230 MeV were observed. The three decay chains originated from the even-even isotope {sup 294}118 (E{sub {alpha}} = 11.65 {+-} 0.06 MeV, T{sub {alpha}} = 0.89{sub -0.31}{sup +1.07} ms) produced in the 3n-evaporation channel of the {sup 249}Cf+{sup 48}Ca reaction with a maximum cross section of 0.5{sub -0.3}{sup +1.6} pb
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