A Limited Sero-Surveillance of Foot and Mouth Disease in Sheep in Egypt

The present work was carried out to evaluate the current status of Foot and Mouth Disease (FMD) in sheep in Egypt. Blood-sera of sheep (N.= 100) located in different areas of 5 Governorates; Menofia, Giza, Fayoum, Beni-Sueif and Menia, were collected and serologically tested during 2010. Fifty samples of saliva and oesopharyngeal fluid were collected and examined virologically. Serum neutralization test and enzyme linked immunosorbant assay (ELISA) indicated that 16 % of the tested sera were positive to FMD-antibodies against type O1 and A. PrioCHECK blocking ELISA was achieved and indicated that 100% of detected FMD antibodies were due to infection. Trials of virus isolation in baby mice and calf kidney cell culture indicated that both types of FMD virus (O1 & A) are existed and persisted in Egyptian sheep. It could be recommended that great importance should be practiced of sheep vaccination with the local bivalent FMD vaccine to restrict the spread of infection and to control FMD

On the energy-momentum tensor in non-commutative gauge theories

We study the properties of the energy-momentum tensor in non-commutative gauge theories by coupling them to a weak external gravitational field. In particular, we show that the stress tensor of such a theory coincides exactly with that derived from a theory where a Seiberg-Witten map has been implemented (namely, the procedure is commutative). Various other interesting features are also discussed.Comment: 3 page

Superspace formulations of the (super)twistor string

The superspace formulation of the worldvolume action of twistor string models is considered. It is shown that for the Berkovits-Siegel closed twistor string such a formulation is provided by a N=4 twistor-like action of the tensionless superstring. A similar inverse twistor transform of the open twistor string model (Berkovits model) results in a dynamical system containing two copies of the D=4, N=4 superspace coordinate functions, one left-moving and one right-moving, that are glued by the boundary conditions. We also discuss possible candidates for a tensionful superstring action leading to the twistor string in the tensionless limit as well as multidimensional counterparts of twistor strings in the framework of both `standard' superspace and superspace enlarged by tensorial coordinates (tensorial superspaces), which constitute a natural framework for massless higher spin theories.Comment: Rev Tex, 13 pages, no figure

The geometry of N=4 twisted string

We compare N=2 string and N=4 topological string within the framework of the sigma model approach. Being classically equivalent on a flat background, the theories are shown to lead to different geometries when put in a curved space. In contrast to the well studied Kaehler geometry characterising the former case, in the latter case a manifold has to admit a covariantly constant holomorphic two-form in order to support an N=4 twisted supersymmetry. This restricts the holonomy group to be a subgroup of SU(1,1) and leads to a Ricci--flat manifold. We speculate that, the N=4 topological formalism is an appropriate framework to smooth down ultraviolet divergences intrinsic to the N=2 theory.Comment: 20 pages, LaTe

Search for charged-lepton-flavour violation in Z-boson decays with the ATLAS detector

Published online: 1 July 2021Leptons with essentially the same properties apart from their mass are grouped into three families (or flavours). The number of leptons of each flavour is conserved in interactions, but this is not imposed by fundamental principles. Since the formulation of the standard model of particle physics, the observation of flavour oscillations among neutrinos has shown that lepton flavour is not conserved in neutrino weak interactions. So far, there has been no experimental evidence that this also occurs in interactions between charged leptons. Such an observation would be a sign of undiscovered particles or a yet unknown type of interaction. Here the ATLAS experiment at the Large Hadron Collider at CERN reports a constraint on lepton-flavour-violating effects in weak interactions, searching for Z-boson decays into a τ lepton and another lepton of different flavour with opposite electric charge. The branching fractions for these decays are measured to be less than 8.1 × 10−6 (eτ) and 9.5 × 10−6 (μτ) at the 95% confidence level using 139 fb−1 of proton–proton collision data at a centre-of-mass energy of s√=13TeV and 20.3 fb−1 at s√=8TeV. These results supersede the limits from the Large Electron–Positron Collider experiments conducted more than two decades ago.G. Aad ... D. Duvnjak ... P. Jackson ... A. X. Y. Kong ... J. L. Oliver ...H. Potti ... T.A. Ruggeri ... K. Sato ... A. S. Sharma ... M.J. White ... et al. (ATLAS Collaboration

Gravity, Twistors and the MHV Formalism

We give a self-contained derivation of the MHV amplitudes for gravity and use the associated twistor generating function to define a twistor action for the MHV diagram approach to gravity. Starting from a background field calculation on a spacetime with anti self-dual curvature, we obtain a simple spacetime formula for the scattering of a single, positive helicity linearized graviton into one of negative helicity. Re-expressing our integral in terms of twistor data allows us to consider a spacetime that is asymptotic to a superposition of plane waves. Expanding these out perturbatively yields the gravitational MHV amplitudes of Berends, Giele & Kuijf. We go on to take the twistor generating function off-shell at the perturbative level. Combining this with a twistor action for the anti self-dual background, we obtain a twistor action for the MHV diagram approach to perturbative gravity. We finish by extending these results to supergravity, in particular N=4 and N=8.Comment: 39 pages, 3 figures. Minor typos corrected, some clarification adde

A new flavonol glycoside and biological activities of <i>Adenanthera pavonina</i> L. leaves

<div><p><i>Adenanthera pavonina</i> is a plant belonging to family Fabaceae. The 95% ethanol extract (EtOH) of the dried powdered leaves of the plant and successive extracts with solvents of increasing polarities were prepared. Fractionation of the successive aqueous EtOH extract on polyamide column and purification of the isolated compounds on Sephadex LH20 led to the isolation of a new methoxy flavonol glycoside named as quercetin 3-<i>O</i>-α-dirhamnopyranosyl-(1‴ → 2″,1″″ → 6″)-β-glucopyranoside-4′-methoxy (<b>1</b>), as well as kaempferol-3-<i>O</i>-α-dirhamnopyranosyl-(1‴ → 2″,1″″ → 6″)-β-glucopyranoside (<b>2</b>), isovitexin (<b>3</b>), quercetin-3-<i>O</i>-rhamnopyranosyl(1‴ → 4″)-β-glucopyranoside (<b>4</b>), quercetin-3-<i>O</i>-β-glucopranoside-4′-<i>O-</i>rhamnopyranoside (<b>5</b>), kaempferol-3-<i>O</i>-α-rhamnopyranosyl(1‴ → 2″)-β-glucopyranoside (<b>6</b>), quercetin-3-<i>O</i>-rhamnopyranosyl(1‴ → 2″)-β-glucopyranoside (<b>7</b>), quercetin-3-<i>O</i>-β-glucopyranoside (<b>8</b>), kaempferol (<b>9</b>) and quercetin (<b>10</b>). Structures of the isolated compounds were established by spectroscopic analysis. Antioxidant activities of EtOH extract, successive extracts and compounds <b>1</b> and <b>2</b> were evaluated. The ethyl acetate (EtOAc) extract and EtOH extract showed 62.67% and 49.30% free radical scavenging activity, respectively. Cytotoxic activities of the EtOH extract and compounds (<b>1</b>) and (<b>2</b>) were evaluated. The EtOH extract showed a significant cytotoxic activity against Hep G-2 (IC₅₀ = 2.50 μg) as compared with cisplatin (IC₅₀>10 μg).</p></div