116 research outputs found

    Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

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    A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

    Measurement of D*+/- meson production in jets from pp collisions at sqrt(s) = 7 TeV with the ATLAS detector

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    This paper reports a measurement of D*+/- meson production in jets from proton-proton collisions at a center-of-mass energy of sqrt(s) = 7 TeV at the CERN Large Hadron Collider. The measurement is based on a data sample recorded with the ATLAS detector with an integrated luminosity of 0.30 pb^-1 for jets with transverse momentum between 25 and 70 GeV in the pseudorapidity range |eta| < 2.5. D*+/- mesons found in jets are fully reconstructed in the decay chain: D*+ -> D0pi+, D0 -> K-pi+, and its charge conjugate. The production rate is found to be N(D*+/-)/N(jet) = 0.025 +/- 0.001(stat.) +/- 0.004(syst.) for D*+/- mesons that carry a fraction z of the jet momentum in the range 0.3 < z < 1. Monte Carlo predictions fail to describe the data at small values of z, and this is most marked at low jet transverse momentum.Comment: 10 pages plus author list (22 pages total), 5 figures, 1 table, matches published version in Physical Review

    Search for supersymmetry in final states with jets, missing transverse momentum and one isolated lepton in sqrt{s} = 7 TeV pp collisions using 1 fb-1 of ATLAS data

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    We present an update of a search for supersymmetry in final states containing jets, missing transverse momentum, and one isolated electron or muon, using 1.04 fb^-1 of proton-proton collision data at sqrt{s} = 7 TeV recorded by the ATLAS experiment at the LHC in the first half of 2011. The analysis is carried out in four distinct signal regions with either three or four jets and variations on the (missing) transverse momentum cuts, resulting in optimized limits for various supersymmetry models. No excess above the standard model background expectation is observed. Limits are set on the visible cross-section of new physics within the kinematic requirements of the search. The results are interpreted as limits on the parameters of the minimal supergravity framework, limits on cross-sections of simplified models with specific squark and gluino decay modes, and limits on parameters of a model with bilinear R-parity violation.Comment: 18 pages plus author list (30 pages total), 9 figures, 4 tables, final version to appear in Physical Review

    HPLC-MS method for simultaneous quantification of the antiretroviral agents rilpivirine and cabotegravir in rat plasma and tissues

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    The antiretroviral agents rilpivirine (RPV) and cabotegravir (CAB) are approved as a combined treatmentregimen against human immunodeficiency virus (HIV). To fully understand the biodistribution of these agentsand determine their concentration levels in various parts of the body, a simple, selective and sensitive bioanalytical method is essential. In the present study, a high performance liquid chromatography method with mass spectrometry detection (HPLC-MS) was developed for simultaneous detection and quantification of RPVand CAB in various biological matrices. These included plasma, skin, lymph nodes, vaginal tissue, liver, kidneysand spleen, harvested from female Sprague Dawley rats. The suitability of the developed method for each matrixwas validated based on the guidelines of the International Council for Harmonisation of Technical Requirementsfor Registration of Pharmaceuticals for Human Use (ICH) on bioanalytical method validation. Analytes wereextracted from biological samples employing a simple one-step protein precipitation method using acetonitrile.Samples were analysed using an Apex Scientific Inertsil ODS-3 column (4.6 mm × 250 mm, 5 µm particle size),maintained at 40 ◦C, on a HPLC system coupled with a single quadrupole MS detector. RPV was detected at amass-to-charge ratio (m/z) of 367.4 and CAB at 406.3. Separation was achieved using isocratic elution at 0.3 mL/min with a mixture of acetonitrile and 0.1% (v/v) trifluoroacetic acid in water (81:19, v/v) as the mobile phase.The run time was set at 13 min. The presented method was selective, sensitive, accurate and precise for detectionand quantification of RPV and CAB in all matrices. The developed and validated bioanalytical method wassuccessfully employed for in vivo samples with both drugs simultaneously

    Development and Evaluation of Dissolving Microarray Patches for Co-administered and Repeated Intradermal Delivery of Long-acting Rilpivirine and Cabotegravir Nanosuspensions for Paediatric HIV Antiretroviral Therapy

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    Purpose Whilst signifcant progress has been made to defeat HIV infection, the efcacy of antiretroviral (ARV) therapyin the paediatric population is often hindered by poor adherence. Currently, two long-acting (LA) intramuscular injectablenanosuspensions of rilpivirine (RPV) and cabotegravir (CAB) are in clinical development for paediatric populations. However, administration requires access to healthcare resources, is painful, and can result in needle-stick injuries to the end user.To overcome these barriers, this proof-of-concept study was developed to evaluate the intradermal delivery of RPV LA andCAB LA via self-disabling dissolving microarray patches (MAPs).Methods Dissolving MAPs of two conformations, a conventional pyramidal and a bilayer design, were formulated, withvarious nanosuspensions of RPV and CAB incorporated within the respective MAP matrix. MAPs were mechanically robustand were capable of penetrating ex vivo skin with intradermal ARV deposition.Results In a single-dose in vivo study in rats, all ARV MAPs demonstrated sustained release profles, with therapeuticallyrelevant plasma concentrations of RPV and CAB detected to at least 63 and 28 d, respectively. In a multi-dose in vivo study,repeated MAP applications at 14-d intervals maintained therapeutically relevant plasma concentrations throughout theduration of the study.Conclusions These results illustrate the potential of the platform to repeatedly maintain plasma concentrations for RPVand CAB. As such, these MAPs could represent a viable option to improve adherence in the paediatric population, one thatis capable of being painlessly administered in the comfort of the patient’s own home on a biweekly or less frequent basis

    Reducing heterotic M-theory to five dimensional supergravity on a manifold with boundary

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    This paper constructs the reduction of heterotic MM-theory in eleven dimensions to a supergravity model on a manifold with boundary in five dimensions using a Calabi-Yau three-fold. New results are presented for the boundary terms in the action and for the boundary conditions on the bulk fields. Some general features of dualisation on a manifold with boundary are used to explain the origin of some topological terms in the action. The effect of gaugino condensation on the fermion boundary conditions leads to a `twist' in the chirality of the gravitino which can provide an uplifting mechanism in the vacuum energy to cancel the cosmological constant after moduli stabilisation.Comment: 16 pages, RevTe

    Measurement of tau polarization in W->taunu decays with the ATLAS detector in pp collisions at sqrt(s) = 7 TeV

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    In this paper, a measurement of tau polarization in W->taunu decays is presented. It is measured from the energies of the decay products in hadronic tau decays with a single final state charged particle. The data, corresponding to an integrated luminosity of 24 pb^-1, were collected by the ATLAS experiment at the Large Hadron Collider in 2010. The measured value of the tau polarization is Ptau = -1.06 +/- 0.04 (stat) + 0.05 (syst) - 0.07 (syst), in agreement with the Standard Model prediction, and is consistent with a physically allowed 95% CL interval [-1,-0.91]. Measurements of tau polarization have not previously been made at hadron colliders.Comment: 10 pages plus author list (25 pages total), 4 figures, 4 tables, revised author list, matches published EPJC versio

    Readiness of the ATLAS liquid argon calorimeter for LHC collisions

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    The ATLAS liquid argon calorimeter has been operating continuously since August 2006. At this time, only part of the calorimeter was readout, but since the beginning of 2008, all calorimeter cells have been connected to the ATLAS readout system in preparation for LHC collisions. This paper gives an overview of the liquid argon calorimeter performance measured in situ with random triggers, calibration data, cosmic muons, and LHC beam splash events. Results on the detector operation, timing performance, electronics noise, and gain stability are presented. High energy deposits from radiative cosmic muons and beam splash events allow to check the intrinsic constant term of the energy resolution. The uniformity of the electromagnetic barrel calorimeter response along eta (averaged over phi) is measured at the percent level using minimum ionizing cosmic muons. Finally, studies of electromagnetic showers from radiative muons have been used to cross-check the Monte Carlo simulation. The performance results obtained using the ATLAS readout, data acquisition, and reconstruction software indicate that the liquid argon calorimeter is well-prepared for collisions at the dawn of the LHC era.ATLAS Collaboration, for complete list of authors see http://dx.doi.org/10.1140/epjc/s10052-010-1354-y</p

    X-Ray Detection of a Pre-Supernova Evolution for the SN 1993J Progenitor

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    We report on the first detection of a pre-supernova (SN) evolution in the X-ray regime. The results are based on ROSAT observations of SN 1993J ranging from six days to five years after the outburst. The X-ray observations are used to probe the SN shell interaction with the ambient circumstellar matter (CSM). After exploring various scenarios that might explain the observed X-ray lightcurve with a t^-0.27 rate of decline, we present a coherent picture in terms of the interaction of the SN shock front with the CSM deposited by the progenitor's stellar wind. During the observed period, the SN shell has reached a radius of 3x10^17 cm from the site of the explosion, corresponding to ~10^4 years in the progenitors stellar wind history. Our analysis shows that the mass-loss rate of the progenitor has decreased constantly from \dot{M} = 4x10^-4 to 4x10^-5 M_sun/yr (v_w/10 km/s) during the late stage of the evolution. Assuming a spherically symmetric expansion, the circumstellar matter density profile is found to be significantly flatter (\rho_csm \propto r^-1.63) than expected for a constant mass-loss rate and constant wind velocity profile (r^-2). The observed evolution either reflects a decrease in the mass-loss rate, an increase in the wind speed or a combination of both, indicating that the progenitor likely was making a transition from the red to the blue supergiant phase during the late stage of its evolution.Comment: 5 pages, 3 figures, accepted for publication in the Astrophysical Journal Letter
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