200 research outputs found
Measurement of the t(t)over-bar production cross section in the dilepton channel in pp collisions at âs=8 TeV
The top-antitop quark (t (t) over bar) production cross section is measured in proton-proton collisions at root s = 8 TeV with the CMS experiment at the LHC, using a data sample corresponding to an integrated luminosity of 5.3 fb(-1). The measurement is performed by analysing events with a pair of electrons or muons, or one electron and one muon, and at least two jets, one of which is identified as originating from hadronisation of a bottom quark. The measured cross section is 239 +/- 2 (stat.) +/- 11 (syst.) +/- 6 (lum.) pb, for an assumed top-quark mass of 172.5 GeV, in agreement with the prediction of the standard model
X-ray emission from the Sombrero galaxy: discrete sources
We present a study of discrete X-ray sources in and around the
bulge-dominated, massive Sa galaxy, Sombrero (M104), based on new and archival
Chandra observations with a total exposure of ~200 ks. With a detection limit
of L_X = 1E37 erg/s and a field of view covering a galactocentric radius of ~30
kpc (11.5 arcminute), 383 sources are detected. Cross-correlation with Spitler
et al.'s catalogue of Sombrero globular clusters (GCs) identified from HST/ACS
observations reveals 41 X-rays sources in GCs, presumably low-mass X-ray
binaries (LMXBs). We quantify the differential luminosity functions (LFs) for
both the detected GC and field LMXBs, whose power-low indices (~1.1 for the
GC-LF and ~1.6 for field-LF) are consistent with previous studies for
elliptical galaxies. With precise sky positions of the GCs without a detected
X-ray source, we further quantify, through a fluctuation analysis, the GC LF at
fainter luminosities down to 1E35 erg/s. The derived index rules out a
faint-end slope flatter than 1.1 at a 2 sigma significance, contrary to recent
findings in several elliptical galaxies and the bulge of M31. On the other
hand, the 2-6 keV unresolved emission places a tight constraint on the field
LF, implying a flattened index of ~1.0 below 1E37 erg/s. We also detect 101
sources in the halo of Sombrero. The presence of these sources cannot be
interpreted as galactic LMXBs whose spatial distribution empirically follows
the starlight. Their number is also higher than the expected number of cosmic
AGNs (52+/-11 [1 sigma]) whose surface density is constrained by deep X-ray
surveys. We suggest that either the cosmic X-ray background is unusually high
in the direction of Sombrero, or a distinct population of X-ray sources is
present in the halo of Sombrero.Comment: 11 figures, 5 tables, ApJ in pres
Patient profiling for success after weight loss surgery (GO Bypass study): an interdisciplinary study protocol
Despite substantial research efforts, the mechanisms proposed to explain weight loss after gastric bypass (RYGB) and sleeve gastrectomy (SL) do not explain the large individual variation seen after these treatments. A complex set of factors are involved in the onset and development of obesity and these may also be relevant for the understanding of why success with treatments vary considerably between individuals. This calls for explanatory models that take into account not only biological determinants but also behavioral, affective and contextual factors. In this prospective study, we recruited 47 women and 8 men, aged 25â56 years old, with a BMI of 45.8âŻÂąâŻ7.1âŻkg/m2 from the waiting list for RYGB and SL at Køge hospital, Denmark. Pre-surgery and 1.5, 6 and 18 months after surgery we assessed various endpoints spanning multiple domains. Endpoints were selected on basis of previous studies and include: physiological measures: anthropometrics, vital signs, biochemical measures and appetite hormones, genetics, gut microbiota, appetite sensation, food and taste preferences, neural sensitivity, sensory perception and movement behaviors; psychological measures: general psychiatric symptom-load, depression, eating disorders, ADHD, personality disorder, impulsivity, emotion regulation, attachment pattern, general self-efficacy, alexithymia, internalization of weight bias, addiction, quality of life and trauma; and sociological and anthropological measures: sociodemographic measures, eating behavior, weight control practices and psycho-social factors. Joining these many endpoints and methodologies from different scientific disciplines and creating a multi-dimensional predictive model has not previously been attempted. Data on the primary endpoint are expected to be published in 2018
Sobrecarga de ferro transfusional em portadores de anemia falciforme: comparação entre ressonância magnÊtica e ferritina sÊrica
OBJETIVO: Identificar variĂĄveis preditoras de sobrecarga de ferro em portadores de anemia falciforme e correlacionar indicadores bioquĂmicos e imaginolĂłgicos.
MATERIAiS E MĂTODOS: Foi realizado estudo transversal envolvendo 32 portadores de anemia falciforme, que foram submetidos a dosagem sĂŠrica de ferro, ferritina e a ressonância magnĂŠtica do fĂgado. Foram realizadas cinco sequĂŞncias gradiente-eco e uma spin-eco. A intensidade de sinal foi obtida em cada sequĂŞncia pelas mĂŠdias das regiĂľes de interesse no fĂgado e musculatura paravertebral para obter a razĂŁo da intensidade de sinal (RIS) fĂgado/mĂşsculo. A partir da RIS foi obtida a concentração hepĂĄtica estimada de ferro (CHEF) pela fĂłrmula: e[5,808 - (0,877 Ă T2*) - (1,518 Ă PI)], onde T2* ĂŠ a RIS na sequĂŞncia com TE de 13 ms e PI ĂŠ a RIS da sequĂŞncia com ponderação intermediĂĄria. Os pacientes foram agrupados segundo o regime de transfusĂŁo de hemĂĄcias (regulares mensais versus esporĂĄdicas).
RESULTADOS: Os grupos transfusionais foram comparados pelas variĂĄveis clĂnico-laboratoriais, sendo significativas as diferenças entre RIS, CHEF e ferritina sĂŠrica: o grupo que recebeu transfusĂľes regulares apresentou sobrecarga de ferro hepĂĄtico mais intensa.
CONCLUSĂO: A ressonância magnĂŠtica foi ferramenta eficiente para avaliação de sobrecarga hepĂĄtica de ferro em portadores de anemia falciforme
Measurement of Higgs boson production and properties in the WW decay channel with leptonic final states
Peer reviewe
Study of B Meson Production in p plus Pb Collisions at root s(NN)=5.02 TeV Using Exclusive Hadronic Decays
Peer reviewe
Measurement of the t(t)over-bar production cross section in pp collisions at root s=7 TeV in dilepton final states containing a tau
The top quark pair production cross section is measured in dilepton events with one electron or muon, and one hadronically decaying tau lepton from the decay t (t) over bar -> (l nu(l))((sic)(h)nu((sic)))b (b) over bar, (l = e, mu). The data sample corresponds to an integrated luminosity of 2.0 fb(-1) for the electron channel and 2.2 fb(-1) for the muon channel, collected by the CMS detector at the LHC. This is the first measurement of the t (t) over bar cross section explicitly including tau leptons in proton- proton collisions at root s = 7 TeV. The measured value sigma(t (t) over bar) = 143 +/- 14(stat) +/- 22(syst) +/- 3(lumi) pb is consistent with the standard model predictions
Search for dijet resonances in 7 TeV pp collisions at CMS
This is the Pre-print version of the Article. The official published version of the paper can be accessed from the link below - Copyright @ 2010 APSA search for narrow resonances in the dijet mass spectrum is performed using data corresponding to an integrated luminosity of 2.9ââpb-1 collected by the CMS experiment at the Large Hadron Collider. Upper limits at the 95% confidence level are presented on the product of the resonance cross section, branching fraction into dijets, and acceptance, separately for decays into quark-quark, quark-gluon, or gluon-gluon pairs. The data exclude new particles predicted in the following models at the 95% confidence level: string resonances, with mass less than 2.50 TeV, excited quarks, with mass less than 1.58 TeV, and axigluons, colorons, and E6 diquarks, in specific mass intervals. This extends previously published limits on these models.This work is supported by FMSR (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES (Croatia); RPF (Cyprus); Academy of Sciences and NICPB (Estonia); Academy of Finland, ME, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NKTH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF and WCU (Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLP-FAI (Mexico); PAEC (Pakistan); SCSR (Poland); FCT (Portugal); JINR (Armenia, Belarus, Georgia, Ukraine, Uzbekistan); MST and MAE (Russia); MSTD (Serbia); MICINN and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); TUBITAK and TAEK (Turkey); STFC (United Kingdom); DOE and NSF (USA)
Search for supersymmetry in events with b jets and missing transverse momentum at the LHC
A search for supersymmetry is presented using a sample of events with b jets and missing transverse momentum. The search uses a data sample of proton-proton collisions at a centre-of-mass energy of 7TeV, corresponding to an integrated luminosity of 35 pb(-1), collected with the CMS detector. A total of 0.33(-0.33)(+0.43) (stat.) +/- 0.13 (syst.) events is predicted, using control samples in the data, to arise from standard model processes, and one event is observed in the data. Upper limits are set at the 95% confidence level on the cross sections of benchmark supersymmetric models
Indications of suppression of excited ÎĽ states in Pb-Pb collisions at âsNN = 2.76TeV
This is the pre-print version of the Published Article which can be accessed from the link below.A comparison of the relative yields of ÎĽ resonances in the Îź+Îź- decay channel in Pb-Pb and pp collisions at a center-of-mass energy per nucleon pair of 2.76 TeV is performed with data collected with the CMS detector at the LHC. Using muons of transverse momentum above 4ââGeV/c and pseudorapidity below 2.4, the double ratio of the ÎĽ(2S) and ÎĽ(3S) excited states to the ÎĽ(1S) ground state in Pb-Pb and pp collisions, [ÎĽ(2S+3S)/ÎĽ(1S)]Pb-Pb/[ÎĽ(2S+3S)/ÎĽ(1S)]pp, is found to be 0.31-0.15+0.19(stat)Âą0.03(syst). The probability to obtain the measured value, or lower, if the true double ratio is unity, is calculated to be less than 1%
- âŚ