7,307 research outputs found

    The impact of new neutrino DIS and Drell-Yan data on large-x parton distributions

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    New data sets have recently become available for neutrino and antineutrino deep inelastic scattering on nuclear targets and for inclusive dimuon production in pp pd interactions. These data sets are sensitive to different combinations of parton distribution functions in the large-x region and, therefore, provide different constraints when incorporated into global parton distribution function fits. We compare and contrast the effects of these new data on parton distribution fits, with special emphasis on the effects at large x. The effects of the use of nuclear targets in the neutrino and antineutrino data sets are also investigated.Comment: 24 pages, 13 figure

    Huddle test measurement of a near Johnson noise limited geophone

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    In this paper, the sensor noise of two geophone configurations (L-22D and L-4C geophones from Sercel with custom built amplifiers) was measured by performing two huddle tests. It is shown that the accuracy of the results can be significantly improved by performing the huddle test in a seismically quiet environment and by using a large number of reference sensors to remove the seismic foreground signal from the data. Using these two techniques, the measured sensor noise of the two geophone configurations matched the calculated predictions remarkably well in the bandwidth of interest (0.01 Hz–100 Hz). Low noise operational amplifiers OPA188 were utilized to amplify the L-4C geophone to give a sensor that was characterized to be near Johnson noise limited in the bandwidth of interest with a noise value of 10−11 m/Hz⎯⎯⎯⎯⎯√10−11 m/Hz at 1 Hz

    Generic User Process Interface for Event Generators

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    Generic Fortran common blocks are presented for use by High Energy Physics event generators for the transfer of event configurations from parton level generators to showering and hadronization event generators.Comment: Physics at TeV Colliders II Workshop, Les Houches, France, May 2001 14 pages, 6 figure

    Implications of Hadron Collider Observables on Parton Distribution Function Uncertainties

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    Standard parton distribution function sets do not have rigorously quantified uncertainties. In recent years it has become apparent that these uncertainties play an important role in the interpretation of hadron collider data. In this paper, using the framework of statistical inference, we illustrate a technique that can be used to efficiently propagate the uncertainties to new observables, assess the compatibility of new data with an initial fit, and, in case the compatibility is good, include the new data in the fit.Comment: 22 pages, 5 figure

    Transport equations for the inflationary trispectrum

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    We use transport techniques to calculate the trispectrum produced in multiple-field inflationary models with canonical kinetic terms. Our method allows the time evolution of the local trispectrum parameters, tauNL and gNL, to be tracked throughout the inflationary phase. We illustrate our approach using examples. We give a simplified method to calculate the superhorizon part of the relation between field fluctuations on spatially flat hypersurfaces and the curvature perturbation on uniform density slices, and obtain its third-order part for the first time. We clarify how the 'backwards' formalism of Yokoyama et al. relates to our analysis and other recent work. We supply explicit formulae which enable each inflationary observable to be computed in any canonical model of interest, using a suitable first-order ODE solver.Comment: 24 pages, plus references and appendix. v2: matches version published in JCAP; typo fixed in Eq. (54

    Optical Microscopy and Atomic Force Microscopy Imaging of 2,4,6-Trinitrotoluene Droplets and Clusters on Mica

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    Optical and atomic force microscopy (AFM) were used to image 2,4,6-trinitrotoluene (TNT) on a cleaved mica (001) surface. The vapor deposition of TNT resulted in ellipsoidal drop formation on the mica surface. The growth rate of the drop diameter was found to be linear with vapor dosing time while the drop density followed a 1/r2 dependence, where r is the length of the major axis of the ellipsoid, for increasing dosing times. TNT platelets surrounded by a region depleted of drops were observed after 8 hours of dosing. The depleted region is attributed to a 10% shrinkage for liquid-solid transition for TNT and also from the enthalpy of fusion which causes the vaporization of small drops and clusters of TNT. Residues of TNT located in the depleted regions were characterized by AFM lift-off forces and were attributed to different morphologies of TNT that nucleated at different sites on the mica surface or dinitro- and trinitro-benzene derivatives which are common impurities in 2,4,6-trinitrotoluene

    Unique Residues Involved in Activation of the Multitasking Protease/Chaperone HtrA from Chlamydia trachomatis

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    DegP, a member of the HtrA family of proteins, conducts critical bacterial protein quality control by both chaperone and proteolysis activities. The regulatory mechanisms controlling these two distinct activities, however, are unknown. DegP activation is known to involve a unique mechanism of allosteric binding, conformational changes and oligomer formation. We have uncovered a novel role for the residues at the PDZ1:protease interface in oligomer formation specifically for chaperone substrates of Chlamydia trachomatis HtrA (DegP homolog). We have demonstrated that CtHtrA proteolysis could be activated by allosteric binding and oligomer formation. The PDZ1 activator cleft was required for the activation and oligomer formation. However, unique to CtHtrA was the critical role for residues at the PDZ1:protease interface in oligomer formation when the activator was an in vitro chaperone substrate. Furthermore, a potential in vivo chaperone substrate, the major outer membrane protein (MOMP) from Chlamydia, was able to activate CtHtrA and induce oligomer formation. Therefore, we have revealed novel residues involved in the activation of CtHtrA which are likely to have important in vivo implications for outer membrane protein assembly

    Koala cathelicidin PhciCath5 has antimicrobial activity, including against Chlamydia pecorum.

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    Devastating fires in Australia over 2019-20 decimated native fauna and flora, including koalas. The resulting population bottleneck, combined with significant loss of habitat, increases the vulnerability of remaining koala populations to threats which include disease. Chlamydia is one disease which causes significant morbidity and mortality in koalas. The predominant pathogenic species, Chlamydia pecorum, causes severe ocular, urogenital and reproductive tract disease. In marsupials, including the koala, gene expansions of an antimicrobial peptide family known as cathelicidins have enabled protection of immunologically naïve pouch young during early development. We propose that koala cathelicidins are active against Chlamydia and other bacteria and fungi. Here we describe ten koala cathelicidins, five of which contained full length coding sequences that were widely expressed in tissues throughout the body. Focusing on these five, we investigate their antimicrobial activity against two koala C. pecorum isolates from distinct serovars; MarsBar and IPTaLE, as well as other bacteria and fungi. One cathelicidin, PhciCath5, inactivated C. pecorum IPTaLE and MarsBar elementary bodies and significantly reduced the number of inclusions compared to the control (p<0.0001). Despite evidence of cathelicidin expression within tissues known to be infected by Chlamydia, natural PhciCath5 concentrations may be inadequate in vivo to prevent or control C. pecorum infections in koalas. PhciCath5 also displayed antimicrobial activity against fungi and Gram negative and positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA). Electrostatic interactions likely drive PhciCath5 adherence to the pathogen cell membrane, followed by membrane permeabilisation leading to cell death. Activity against E. coli was reduced in the presence of 10% serum and 20% whole blood. Future modification of the PhciCath5 peptide to enhance activity, including in the presence of serum/blood, may provide a novel solution to Chlamydia infection in koalas and other species

    Examination of direct-photon and pion production in proton-nucleon collisions

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    We present a study of inclusive direct-photon and pion production in hadronic interactions, focusing on a comparison of the ratio of gamma/pi0 yields with expectations from next-to-leading order perturbative QCD (NLO pQCD). We also examine the impact of a phenomenological model involving k_T smearing (which approximates effects of additional soft-gluon emission) on absolute predictions for photon and pion production and their ratio.Comment: 20 pages, 12 figures. Minor changes in wording and in figure
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