102 research outputs found

    N=2 supersymmetric Yang-Mills theory and the superparticle: twistor transform and kappa-symmetry

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    Lagrangian and Hamiltonian dynamics of de Azcarraga-Lukierski N=2 massive superparticle is considered in the framework of twistor-like Lorentz-harmonic approach. The emphasis is on the study of the interaction with external Abelian gauge superfield. The requirement of preservation of all gauge symmetries of the free model including kappa-symmetry yields correct expressions for the superfield strength constraints and determines the form of nonminimal interaction. We also show that for de Azcarraga-Lukierski N=2 massive superparticle the pullback of field strength 2-superform to the superworld line is not integrable in contrast to the massless superparticle.Comment: 16 pages, LaTe

    Anti- Schistosomular Activity of Human Monocytes/Macrophages in Response to Interleukin-3 and Granulocyte-Macrophage Colonystimulating Factor Stimulation

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    Human monocytes, co-incubated for 7 days in culture with GM-CSF or IL-3 but not with IFN-γ, exerted a variable schistosotnulicidal effect on Schistosoma mansoni parasites when grown in 96-well round-bottomed plates but not in flat-bottomed plates. Addition of LPS or IFN-γ or both, for the last 48 h did not enhance the cidal effect. Addition of LPS but not IFN-γ to the pre-incubated cells with GM-CSF or IL-3 markedly stimulated TNF-α production by the cells but not their cidal activity. The variable cidal effects obtained with the monocytes/macrophages from different donors suggest that these effects may be genetically predetermined and are possibly linked to blood group markers or to MHC class I or II antigens

    Weyl-Conformally-Invariant Lightlike p-Brane Theories: New Aspects in Black Hole Physics and Kaluza-Klein Dynamics

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    We introduce and study in some detail the properties of a novel class of Weyl-conformally invariant p-brane theories which describe intrinsically lightlike branes for any odd world-volume dimension. Their dynamics significantly differs from that of the ordinary (conformally non-invariant) Nambu-Goto p-branes. We present explicit solutions of the Weyl-invariant lightlike brane- (WILL-brane) equations of motion in various gravitational models of physical relevance exhibiting various new phenomena. In D=4 the WILL-membrane serves as a material and charged source for gravity and electromagnetism in the coupled Einstein-Maxwell-WILL-membrane system; it automatically positions itself on (``straddles'') the common event horizon of the corresponding matching black hole solutions, thus providing an explicit dynamical realization of the membrane paradigm in black hole physics. In product spaces of interest in Kaluza-Klein theories the WILL-brane wraps non-trivially around the compact (internal)dimensions and still describes massless mode dynamics in the non-compact (space-time) dimensions. Due to nontrivial variable size of the internal compact dimensions we find new types of physically interesting solutions describing massless brane modes trapped on bounded planar circular orbits with non-trivial angular momentum, and with linear dependence between energy and angular momentum.Comment: 28 pages, published versio

    Genome Sequence of Stenotrophomonas maltophilia PML168, Which Displays Baeyer-Villiger Monooxygenase Activity

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    Stenotrophomonas maltophilia PML168 was isolated from Wembury Beach on the English Coast from a rock pool following growth and selection on agar plates. Here we present the permanent draft genome sequence, which has allowed prediction of function for several genes encoding enzymes relevant to industrial biotechnology, including a novel flavoprotein monooxygenase

    Negative Even Grade mKdV Hierarchy and its Soliton Solutions

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    In this paper we provide an algebraic construction for the negative even mKdV hierarchy which gives rise to time evolutions associated to even graded Lie algebraic structure. We propose a modification of the dressing method, in order to incorporate a non-trivial vacuum configuration and construct a deformed vertex operator for sl^(2)\hat{sl}(2), that enable us to obtain explicit and systematic solutions for the whole negative even grade equations

    Hiding and Confining Charges via "Tube-like" Wormholes

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    We describe two interesting effects in wormhole physics. First, we find that a genuinely charged matter source may appear neutral to an external observer - a phenomenon opposite to the famous Misner-Wheeler "charge without charge" effect. This phenomenon takes place when coupling a bulk gravity/nonlinear-gauge-field system to a charged lightlike brane as a matter source. The "charge-hiding" effect occurs in a wormhole solution which connects a non-compact "universe", comprising the exterior region of Schwarzschild-(anti-)de-Sitter (SdS) or purely Schwarzschild black hole beyond the Schwarzschild horizon, to a Levi-Civita-Bertotti-Robinson-type (LCBR) "tube-like" "universe" via a wormhole "throat" occupied by the brane. In this solution the whole electric flux produced by the brane is expelled into the "tube-like" "universe" and the brane is detected as neutral by an observer in the non-compact "universe". Next, we find a truly charge-confining wormhole solution when we couple the bulk gravity/nonlinear-gauge-field system to two oppositely charged lightlike branes. The latter system possesses a "two-throat" wormhole solution, where the "left-most" and the "right-most" "universes" are two identical copies of the exterior region of SdS black hole beyond the Schwarzschild horizon, whereas the "middle" "universe" is of LCBR "tube-like" form with geometry dS_2 x S^2. It comprises the finite-extent intermediate region of dS_2 between its two horizons. Both "throats" are occupied by the two oppositely charged lightlike branes and the whole electric flux produced by the latter is confined entirely within the middle "tube-like" "universe". A crucial ingredient is the special form of the nonlinear gauge field action, which contains both the standard Maxwell term as well as a square root of the latter. This theory was previously shown to produce a QCD-like confining dynamics in flat space-time.Comment: 26 pages, 2 figures; v.2 several references added, missing constant factors in few equations inserted, acknowledgement added, results unchanged; v.3 28 pages, several clarifying remarks, references and acknowledgements added, version to appear in International Journal of Modern Physics

    Ocean acidification shows negligible impacts on high-latitude bacterial community structure in coastal pelagic mesocosms

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    The impact of ocean acidification and carbonation on microbial community structure was assessed during a large-scale in situ costal pelagic mesocosm study, included as part of the EPOCA 2010 Arctic campaign. The mesocosm experiment included ambient conditions (fjord) and nine mesocosms, with pCO2 range from ~145 to ~1420 μatm. Samples collected at nine time points (t-1, t1, t5, t7, t12, t14, t22, t26 to t28) in seven treatments (ambient fjord (~145), 2×~185, ~270, ~685, ~820, ~1050 μatm) were analysed for "free-living" and "particle associated" microbial community composition using 16S rRNA amplicon sequencing. This high-throughput sequencing analysis produced ~20 000 000 16S rRNA V4 reads, which comprised 7000 OTUs. The main variables structuring these communities were, sample origin (fjord or mesocosms) and the filter size fraction (free-living or particle associated). The community was significantly different between the fjord and both the control and elevated 2 mesocosms (which were not significant different) after nutrients were added to the mesocosms; suggesting that the addition of nutrients is the primary driver of the change in mesocosm community structure. The relative importance of each structuring variable depended greatly on the time at which the community was sampled in relation to the phytoplankton bloom. The size fraction was the second most important factor for community structure; separating free-living from particle-associated bacteria. When free-living and particle-associated bacteria were analysed separately at different time points, the only taxon pCO2 was found to significantly affect were the Gammaproteobacteria after nutrient addition. Finally, pCO2 treatment was found to be significantly correlated (non-linear) with 15 rare taxa, most of which increased in abundance with higher CO2
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