7,922 research outputs found

    Dual Identities inside the Gluon and the Graviton Scattering Amplitudes

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    Recently, Bern, Carrasco and Johansson conjectured dual identities inside the gluon tree scattering amplitudes. In this paper, we use the properties of the heterotic string and open string tree scattering amplitudes to refine and derive these dual identities. These identities can be carried over to loop amplitudes using the unitarity method. Furthermore, given the MM-gluon (as well as gluon-gluino) tree amplitudes, MM-graviton (as well as graviton-gravitino) tree scattering amplitudes can be written down immediately, avoiding the derivation of Feynman rules and the evaluation of Feynman diagrams for graviton scattering amplitudes.Comment: 43 pages, 3 figures; typos corrected, a few points clarified

    Multi-gluon helicity amplitudes with one off-shell leg within high energy factorization

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    Basing on the Slavnov-Taylor identities, we derive a new prescription to obtain gauge invariant tree-level scattering amplitudes for the process g*g->Ng within high energy factorization. Using the helicity method, we check the formalism up to several final state gluons, and we present analytical formulas for the the helicity amplitudes for N=2. We also compare the method with Lipatov's effective action approach.Comment: 25 pages, quite a few figures, an appendix added, typos correcte

    A prospective, randomized trial to compare tacrolimus and prednisone with and without mycophenolate mofetil in patients undergoing renal transplantation: first report.

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    PURPOSE: Between September 20, 1995 and September 20, 1996, 120 patients were entered into a prospective, randomized trial comparing tacrolimus and prednisone with (61) and without (59) 2 gm. mycophenolate mofetil daily to determine whether mycophenolate mofetil was associated with a lower incidence of rejection. MATERIALS AND METHODS: Mean recipient age plus or minus standard deviation was 50.8+/-14.1 years (range 18.8 to 84.1). Mean donor age was 34.3+/-21.7 years (range 0.01 to 76). Of the donors 18 (15%) were older than 60 years. Mean cold ischemia time was 30.9+/-8.4 hours (range 14.2 to 49). Median followup was 8.6+/-0.5 months. RESULTS: The 6-month actuarial patient survival was 95%, 92% in the double therapy group and 98% in the triple therapy group (not significant). The 6-month actuarial graft survival was 88%, 84% in the double therapy group and 92% in the triple therapy group (not significant). The overall incidence of rejection and steroid resistant rejection was 34.2 and 4.2%, respectively. There was a strong trend toward less rejection in the mycophenolate mofetil group than in the double therapy group (26.2 versus 42.4%). Crossover was common, and was 42.6% from triple to double therapy and 18.6% from double to triple therapy. The reasons for discontinuation of mycophenolate mofetil were gastrointestinal toxicity, primarily diarrhea, or less commonly hematological toxicity, primarily neutropenia or thrombocytopenia. Gastrointestinal toxicity was ameliorated by separating the doses of tacrolimus and mycophenolate mofetil by 2 to 4 hours, and reducing the dose to 1 gm. daily. CONCLUSIONS: Mycophenolate mofetil appears to be a useful third agent with tacrolimus in patients undergoing renal transplantation, and is associated with a reduction in the rate of rejection and a low incidence of steroid resistant rejection. There is a high incidence of gastrointestinal toxicity associated with the 2 gm. daily dose but this complication is relatively straightforward to manage

    General Split Helicity Gluon Tree Amplitudes in Open Twistor String Theory

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    We evaluate all split helicity gluon tree amplitudes in open twistor string theory. We show that these amplitudes satisfy the BCFW recurrence relations restricted to the split helicity case and, hence, that these amplitudes agree with those of gauge theory. To do this we make a particular choice of the sextic constraints in the link variables that determine the poles contributing to the contour integral expression for the amplitudes. Using the residue theorem to re-express this integral in terms of contributions from poles at rational values of the link variables, which we determine, we evaluate the amplitudes explicitly, regaining the gauge theory results of Britto et al.Comment: 30 pages, minor misprints correcte

    The complete mitochondrial genome of the foodborne parasitic pathogen Cyclospora cayetanensis

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    Cyclospora cayetanensis is a human-specific coccidian parasite responsible for several food and water-related outbreaks around the world, including the most recent ones involving over 900 persons in 2013 and 2014 outbreaks in the USA. Multicopy organellar DNA such as mitochondrion genomes have been particularly informative for detection and genetic traceback analysis in other parasites. We sequenced the C. cayetanensis genomic DNA obtained from stool samples from patients infected with Cyclospora in Nepal using the Illumina MiSeq platform. By bioinformatically filtering out the metagenomic reads of non-coccidian origin sequences and concentrating the reads by targeted alignment, we were able to obtain contigs containing Eimeria-like mitochondrial, apicoplastic and some chromosomal genomic fragments. A mitochondrial genomic sequence was assembled and confirmed by cloning and sequencing targeted PCR products amplified from Cyclospora DNA using primers based on our draft assembly sequence. The results show that the C. cayetanensis mitochondrion genome is 6274 bp in length, with 33% GC content, and likely exists in concatemeric arrays as in Eimeria mitochondrial genomes. Phylogenetic analysis of the C. cayetanensis mitochondrial genome places this organism in a tight cluster with Eimeria species. The mitochondrial genome of C. cayetanensis contains three protein coding genes, cytochrome (cytb), cytochrome C oxidase subunit 1 (cox1), and cytochrome C oxidase subunit 3 (cox3), in addition to 14 large subunit (LSU) and nine small subunit (SSU) fragmented rRNA genes

    THE RHYTHM OF FAIRALL 9. I. OBSERVING THE SPECTRAL VARIABILITY WITH XMM-NEWTON AND NuSTAR

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    © 2016. The American Astronomical Society. All rights reserved. We present a multi-epoch X-ray spectral analysis of the Seyfert 1 galaxy Fairall 9. Our analysis shows that Fairall 9 displays unique spectral variability in that its ratio residuals to a simple absorbed power law in the 0.5-10 keV band remain constant with time in spite of large variations in flux. This behavior implies an unchanging source geometry and the same emission processes continuously at work at the timescale probed. With the constraints from NuSTAR on the broad-band spectral shape, it is clear that the soft excess in this source is a superposition of two different processes, one being blurred ionized reflection in the innermost parts of the accretion disk, and the other a continuum component such as a spatially distinct Comptonizing region. Alternatively, a more complex primary Comptonization component together with blurred ionized reflection could be responsible

    Mapping genetic determinants of host susceptibility to Pseudomonas aeruginosa lung infection in mice.

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    Background: P. aeruginosa is one of the top three causes of opportunistic human bacterial infections. The remarkable variability in the clinical outcomes of this infection is thought to be associated with genetic predisposition. However, the genes underlying host susceptibility to P. aeruginosa infection are still largely unknown. Results: As a step towards mapping these genes, we applied a genome wide linkage analysis approach to a mouse model. A large F2 intercross population, obtained by mating P. aeruginosa-resistant C3H/HeOuJ, and susceptible A/J mice, was used for quantitative trait locus (QTL) mapping. The F2 progenies were challenged with a P. aeruginosa clinical strain and monitored for the survival time up to 7 days post-infection, as a disease phenotype associated trait. Selected phenotypic extremes of the F2 distribution were genotyped with high-density single nucleotide polymorphic (SNP) markers, and subsequently QTL analysis was performed. A significant locus was mapped on chromosome 6 and was named P. aeruginosa infection resistance locus 1 (Pairl1). The most promising candidate genes, including Dok1, Tacr1, Cd207, Clec4f, Gp9, Gata2, Foxp1, are related to pathogen sensing, neutrophils and macrophages recruitment and inflammatory processes. Conclusions: We propose a set of genes involved in the pathogenesis of P. aeruginosa infection that may be explored to complement human studie

    First observation of psi(2S)-->K_S K_L

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    The decay psi(2S)-->K_S K_L is observed for the first time using psi(2S) data collected with the Beijing Spectrometer (BESII) at the Beijing Electron Positron Collider (BEPC); the branching ratio is determined to be B(psi(2S)-->K_S K_L) = (5.24\pm 0.47 \pm 0.48)\times 10^{-5}. Compared with J/psi-->K_S K_L, the psi(2S) branching ratio is enhanced relative to the prediction of the perturbative QCD ``12%'' rule. The result, together with the branching ratios of psi(2S) decays to other pseudoscalar meson pairs (\pi^+\pi^- and K^+K^-), is used to investigate the relative phase between the three-gluon and the one-photon annihilation amplitudes of psi(2S) decays.Comment: 5 pages, 4 figures, 2 tables, submitted to Phys. Rev. Let
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