73 research outputs found
Jet energy measurement with the ATLAS detector in proton-proton collisions at root s=7 TeV
The jet energy scale and its systematic uncertainty are determined for jets measured with the ATLAS detector at the LHC in proton-proton collision data at a centre-of-mass energy of âs = 7TeV corresponding to an integrated luminosity of 38 pb-1. Jets are reconstructed with the anti-kt algorithm with distance parameters R=0. 4 or R=0. 6. Jet energy and angle corrections are determined from Monte Carlo simulations to calibrate jets with transverse momenta pTâ„20 GeV and pseudorapidities {pipe}η{pipe}<4. 5. The jet energy systematic uncertainty is estimated using the single isolated hadron response measured in situ and in test-beams, exploiting the transverse momentum balance between central and forward jets in events with dijet topologies and studying systematic variations in Monte Carlo simulations. The jet energy uncertainty is less than 2. 5 % in the central calorimeter region ({pipe}η{pipe}<0. 8) for jets with 60â€pT<800 GeV, and is maximally 14 % for pT<30 GeV in the most forward region 3. 2â€{pipe}η{pipe}<4. 5. The jet energy is validated for jet transverse momenta up to 1 TeV to the level of a few percent using several in situ techniques by comparing a well-known reference such as the recoiling photon pT, the sum of the transverse momenta of tracks associated to the jet, or a system of low-pT jets recoiling against a high-pT jet. More sophisticated jet calibration schemes are presented based on calorimeter cell energy density weighting or hadronic properties of jets, aiming for an improved jet energy resolution and a reduced flavour dependence of the jet response. The systematic uncertainty of the jet energy determined from a combination of in situ techniques is consistent with the one derived from single hadron response measurements over a wide kinematic range. The nominal corrections and uncertainties are derived for isolated jets in an inclusive sample of high-pT jets. Special cases such as event topologies with close-by jets, or selections of samples with an enhanced content of jets originating from light quarks, heavy quarks or gluons are also discussed and the corresponding uncertainties are determined. © 2013 CERN for the benefit of the ATLAS collaboration
Measurement of the inclusive and dijet cross-sections of b-jets in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector
The inclusive and dijet production cross-sections have been measured for jets
containing b-hadrons (b-jets) in proton-proton collisions at a centre-of-mass
energy of sqrt(s) = 7 TeV, using the ATLAS detector at the LHC. The
measurements use data corresponding to an integrated luminosity of 34 pb^-1.
The b-jets are identified using either a lifetime-based method, where secondary
decay vertices of b-hadrons in jets are reconstructed using information from
the tracking detectors, or a muon-based method where the presence of a muon is
used to identify semileptonic decays of b-hadrons inside jets. The inclusive
b-jet cross-section is measured as a function of transverse momentum in the
range 20 < pT < 400 GeV and rapidity in the range |y| < 2.1. The bbbar-dijet
cross-section is measured as a function of the dijet invariant mass in the
range 110 < m_jj < 760 GeV, the azimuthal angle difference between the two jets
and the angular variable chi in two dijet mass regions. The results are
compared with next-to-leading-order QCD predictions. Good agreement is observed
between the measured cross-sections and the predictions obtained using POWHEG +
Pythia. MC@NLO + Herwig shows good agreement with the measured bbbar-dijet
cross-section. However, it does not reproduce the measured inclusive
cross-section well, particularly for central b-jets with large transverse
momenta.Comment: 10 pages plus author list (21 pages total), 8 figures, 1 table, final
version published in European Physical Journal
Intracutaneous suture versus transcutaneous skin stapling for closure of midline or horizontal skin incision in elective abdominal surgery and their outcome on superficial surgical site infectionsâINTRANS: study protocol for a randomized controlled trial
Measurement of the cross-section for b-jets produced in association with a Z boson at root s=7 TeV with the ATLAS detector ATLAS Collaboration
A measurement is presented of the inclusive cross-section for b-jet production in association with a Z boson in pp collisions at a centre-of-mass energy of root s = 7 TeV. The analysis uses the data sample collected by the ATLAS experiment in 2010, corresponding to an integrated luminosity of approximately 36 pb(-1). The event selection requires a Z boson decaying into high P-T electrons or muons, and at least one b-jet, identified by its displaced vertex, with transverse momentum p(T) > 25 GeV and rapidity vertical bar y vertical bar < 2.1. After subtraction of background processes, the yield is extracted from the vertex mass distribution of the candidate b-jets. The ratio of this cross-section to the inclusive Z cross-section (the average number of b-jets per Z event) is also measured. Both results are found to be in good agreement with perturbative QCD predictions at next-to-leading order
Perineal Metastatic Crohn's Disease: A Case Report and Review of the Literature
Metastatic Crohn's disease is an uncommon complication of Crohn's disease defined as granulomatous inflammation not contiguous with inflammatory disease in bowel. We report on the presentation and management of a 36-year-old man, who had undergone panproctocolectomy 11 years ago, with complex fistulous disease in his perineum, which demonstrated granulomas histologically after resection. We review six similar case reports. Optimal treatment would appear to be by surgical debridement
A statistical comparison of silver and SYPRO Ruby staining for proteomic analysis.
Silver staining has been the method most commonly employed for high sensitivity staining of proteins following two-dimensional gel electrophoresis. Whilst this method offers detection in the nanogram range it does have major drawbacks including a lack of linearity, nonstoichiometric staining of proteins, a lack of compatibility with the microchemical preparation of proteins for identification by mass spectrometric techniques, and a highly subjective assessment of the staining endpoint. SYPRO Ruby is a relatively new, ruthenium complex-based stain which is reported to offer advantages over silver, particularly in overcoming the limitations cited above. We describe a series of experiments where several protein staining procedures commonly employed are compared. To enable optimization of the in situ digestion procedure, a statistical approach has been undertaken. The effects of a variety of staining, digestion, and analysis protocols on the downstream processing of a test radiolabeled protein were studied. The data confirms that as well as offering sensitivity similar to silver, SYPRO Ruby staining is reproducible, linear, and offers a higher level of compatibility with the identification of proteins by mass spectrometry
Boltâs Farm Cave System dans le Cradle of Humankind (Afrique du Sud) : un exemple dâapproche multidisciplinaire dans lâĂ©tude des sites Ă primates fossiles
Le Cradle of Humankind en Afrique du Sud prĂ©sente des sites qui sont tous classĂ©s au titre de patrimoine mondial de lâhumanitĂ© par lâUNESCO depuis 1999 (Thackeray, 2016). Ces sites ont livrĂ© des restes dâhominidĂ©s et/ou de primates non-humains (Cercopithecoidea). Robert Broom est le premier Ă rechercher des fossiles dans le Boltâs Farm Cave System (ou BFCS), et ceci dĂšs 1936. Les recherches nây deviennent rĂ©guliĂšres que depuis 2006 avec la crĂ©ation du HRU (Hope (Human Origins and Past Environment) Research Unit). BFCS est surtout connu pour avoir livrĂ© des restes de grands fĂ©lins. Pourtant, certains fossiles de Cercopithecoidea dĂ©couverts Ă BFCS sont des rĂ©fĂ©rences en palĂ©oprimatologie comme BF42 (Cercopithecoides williamsi) et BF43 (Parapapio broomi). Waypoint 160 Ă BFCS a livrĂ© les plus anciens restes de primate non-humain du Cradle of Humankind qui sont datĂ©s du PliocĂšne infĂ©rieur. Pour obtenir plus dâinformations sur le contexte gĂ©ologique et le palĂ©oenvironnement, des fouilles sont menĂ©es depuis 2011 dans certains loci et viennent remplacer les prospections menĂ©es par les membres du HRU. Lâenjeu est dâobtenir le maximum de donnĂ©es sur la palĂ©odiversitĂ©, notamment la microfaune qui doit ĂȘtre extraite des brĂšches par des techniques de prĂ©paration Ă lâacide, sur les conditions de fossilisation et de prĂ©servation des fossiles, ainsi que de pouvoir replacer ces fossiles dans le temps.The Cradle of Humankind in South Africa, recognized as World Heritage by UNESCO since 1999, contains fossil sites which have yielded hominid remains and/or non-human primates (Cercopithecoidea). Robert Broom was the first to prospect for fossils at Bolt's Farm Cave System (or BFCS), and this since 1936. Research only became regular in 2006 with the creation of the HRU (Hope (Human Origins and Past Environment) Research Unit). BFCS is best known for yielding remains of large cats. Yet some fossils of Cercopithecoidea discovered at BFCS are considered to be references in palaeoprimatology: BF42 (Cercopithecoides williamsi) and BF43 (Parapapio broomi). Waypoint 160 at BFCS yielded the oldest remains of nonhuman primates in the Cradle of Humankind which are dated to the Pliocene. For more information about the geological and palaeoenvironmental context, excavations were conducted since 2011 in some loci based on the surveys carried out by members of HRU. The present challenge is to obtain the maximum amount of data concerning palaeobiodiversity, including the microfauna which must be extracted from the breccia by acid preparation techniques, study of the conditions of fossilization and the preservation of fossils, as well as the determination of the ages of the fossils
Evaluation of efficacy- versus affinity-driven agonism with biased GLP-1R ligands P5 and exendin-F1
The glucagon-like peptide-1 receptor (GLP-1R) is an important regulator of glucose homeostasis and has been successfully targeted for the treatment of type 2 diabetes. Recently described biased GLP-1R agonists with selective reductions in ÎČ-arrestin versus G protein coupling show improved metabolic actions in vivo. However, two prototypical G protein-favouring GLP-1R agonists, P5 and exendin-F1, are reported to show divergent effects on insulin secretion. In this study we aimed to resolve this discrepancy by performing a side-by-side characterisation of these two ligands across a variety of in vitro and in vivo assays. Exendin-F1 showed reduced acute efficacy versus P5 for several readouts, including recruitment of mini-G proteins, G protein-coupled receptor kinases (GRKs) and ÎČ-arrestin-2. Maximal responses were also lower for both GLP-1R internalisation and the presence of active GLP-1R-mini-Gs complexes in early endosomes with exendin-F1 treatment. In contrast, prolonged insulin secretion in vitro and sustained anti-hyperglycaemic efficacy in mice were both greater with exendin-F1 than with P5. We conclude that the particularly low acute efficacy of exendin-F1 and associated reductions in GLP-1R downregulation appear to be more important than preservation of endosomal signalling to allow sustained insulin secretion responses. This has implications for the ongoing development of affinity- versus efficacy-driven biased GLP-1R agonists as treatments for metabolic disease
The influence of peptide context on signaling and trafficking of glucagon-like peptide-1 receptor biased agonists
Signal bias and membrane trafficking have recently emerged as important considerations in the therapeutic targeting of the glucagon-like peptide-1 receptor (GLP-1R) in type 2 diabetes and obesity. In the present study, we have evaluated a peptide series with varying sequence homology between native GLP-1 and exendin-4, the archetypal ligands on which approved GLP-1R agonists are based. We find notable differences in agonist-mediated cyclic AMP signaling, recruitment of ÎČ-arrestins, endocytosis, and recycling, dependent both on the introduction of a His â Phe switch at position 1 and the specific midpeptide helical regions and C-termini of the two agonists. These observations were linked to insulin secretion in a beta cell model and provide insights into how ligand factors influence GLP-1R function at the cellular level
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