827 research outputs found

    Feasibility of diffusion weighted MR imaging in differentiating recurrent laryngeal carcinoma from radionecrosis

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    AbstractPurposeTo assess the feasibility of apparent diffusion coefficient (ADC) generated from diffusion weighted magnetic resonance imaging as a non invasive technique to differentiate tumor recurrence from radionecrosis in patients with laryngeal carcinoma.Materials and methodsTwenty one patients suspected of tumor recurrence underwent MRI including diffusion weighted imaging (DWI) (b 0 and 1000). ADC maps were generated and ADC values were measured at the lesion sites and the normal laryngeal tissues, and were compared with the histopathological results.ResultsThe mean ADC of tumor recurrence {1.04±0.34×10−3mm2/s (SD)} was significantly lower (p<0.0001) than the mean ADC of the normal laryngeal tissues in the same patient (1.48±0.099×10−3mm2/s) while the mean ADC of radionecrosis (1.79±0.41×10−3mm2/s) was significantly higher (p<0.04) than the mean ADC of the normal laryngeal tissues (1.49±0.095×10−3mm2). The mean ADC of tumor recurrence is significantly lower (p<0.0001) than the mean ADC of radionecrosis with 1.16×10−3mm2/s is the best cut value for differentiating tumor recurrence from radionecrosis.ConclusionADC can differentiate tumor recurrence from radionecrosis in laryngeal carcinoma

    Mise en Ă©vidence d’un SĂ©nonien gypseux sous la sĂ©rie phosphatĂ©e du bassin des Ouled Abdoun: Un nouveau point de dĂ©part pour l’origine des zones dĂ©rangĂ©es dans les mines Ă  ciel ouvert de Khouribga, Maroc

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    In the Ouled Abdoun sedimentary basin (Morocco), the phosphatic series is composed of regular interbedded phosphatic and marly limestone layers. Exploitation of the phosphate in some deposits in this basin collides frequently with problems bound to the existence, in the phosphatic series, of disturbed areas (sterile bodies) qualified as derangements by the mining engineers of the Office Cherifian Phosphate Group (OCP). Their presence in the phosphatic layers causes two kinds of problems: (1) since the whole phosphatic sequence is overlain by a Quaternary cover, we do not know their volume proportion in the phosphatic layers, and therefore the reserves estimations can be wrong (2) they are generally hard, so they complicate the phosphate extraction. Indeed, in an area containing sterile bodies, boring grid may always be tightened and boreholes filled with dynamite. The required borehole tools and use of explosives are time consuming and therefore increase drastically the cost of phosphate extraction. Their localisation would permit the mining engineers to get around them during the exploitation. Several geophysical works have carried out in the achieved in Khouribga area to localize and delimit these sterile bodies. Electric resistitivy was established as a suitable geophysical parameter to map them, but the slowness and difficulty of data collection hinders the application of these geophysical methods to the whose phosphatic deposits area (about 25000 ha). Their application in all the Ouled Abdoun basin requires the comprehension of the origin of the sterile bodies, in order to specify their formation process and to predict consequently their spacial distribution in each phosphatic deposit. Our study concerns to sedimentological and diagenetic analysis of disturbed aereas and their immediate vicinity. It made it possible to identify for the first time the existence of an evaporitic series intensely karstified at the top of the Senonian, under the phosphatic series. The senonian karsts are undoubtedly at the origin of the derangements, which are defined as the collapsing phenomena at the base of underground cavities. These bodies have a polyphase structuring and a genesis that is the consequence of on several processes (fracturing, infiltration, dissolution, collapse). Their installation began from the end of Senonian, and continues up to the Quaternary.[fr] Dans le bassin sĂ©dimentaire des Ouled Abdoun (Maroc), la sĂ©rie phosphatĂ©e est formĂ©e d’une intercalation rĂ©guliĂšre de niveaux phosphatĂ©s et marno-calcaires sur environ 50m de puissance. Localement, cette rĂ©gularitĂ© est perturbĂ©e par la prĂ©sence frĂ©quente de structures communĂ©ment appelĂ©s «dĂ©rangements». Il s’agit de masses non stratifiĂ©es, stĂ©riles, qui perturbent et alourdissent les travaux d’exploitation des couches phosphatĂ©es. Les Ă©tudes gĂ©ophysiques expĂ©rimentales, rĂ©alisĂ©es dans les zones dĂ©rangĂ©es de la sĂ©rie phosphatĂ©e, ont dĂ©montrĂ© la possibilitĂ© de les cartographier sous couvertures Ă  l’échelle dĂ©camĂ©trique. Leur gĂ©nĂ©ralisation sur toute la superficie du bassin des Ouled Abdoun, nĂ©cessite une comprĂ©hension du phĂ©nomĂšne Ă  l’origine de ces structures. Notre Ă©tude concerne l’analyse sĂ©dimentologique et diagĂ©nĂ©tique des zones dĂ©rangĂ©es et de leur voisinage immĂ©diat. Elle a permis d’identifier pour la premiĂšre fois l’existence d’une sĂ©rie Ă©vaporitique intensĂ©ment karstifiĂ©e au sommet du SĂ©nonien, sous la sĂ©rie phosphatĂ©e. Les karsts sĂ©noniens sont incontestablement Ă  l’origine des dĂ©rangements ou fontis que l’on dĂ©fini comme Ă©tant des phĂ©nomĂšnes de collapses Ă  l’aplomb de cavitĂ©s souterraines. Ces fontis ont une structuration polyphasĂ©e et une genĂšse au dĂ©pend de plusieurs processus (fracturation, infiltration, dissolution, effondrement). Leur mise en place a dĂ©butĂ© dĂšs la fin du SĂ©nonien et s’est poursuivie jusqu’au quaternaire

    Measurements of fiducial and differential cross sections for Higgs boson production in the diphoton decay channel at s√=8 TeV with ATLAS

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    Measurements of fiducial and differential cross sections are presented for Higgs boson production in proton-proton collisions at a centre-of-mass energy of s√=8 TeV. The analysis is performed in the H → γγ decay channel using 20.3 fb−1 of data recorded by the ATLAS experiment at the CERN Large Hadron Collider. The signal is extracted using a fit to the diphoton invariant mass spectrum assuming that the width of the resonance is much smaller than the experimental resolution. The signal yields are corrected for the effects of detector inefficiency and resolution. The pp → H → γγ fiducial cross section is measured to be 43.2 ±9.4(stat.) − 2.9 + 3.2 (syst.) ±1.2(lumi)fb for a Higgs boson of mass 125.4GeV decaying to two isolated photons that have transverse momentum greater than 35% and 25% of the diphoton invariant mass and each with absolute pseudorapidity less than 2.37. Four additional fiducial cross sections and two cross-section limits are presented in phase space regions that test the theoretical modelling of different Higgs boson production mechanisms, or are sensitive to physics beyond the Standard Model. Differential cross sections are also presented, as a function of variables related to the diphoton kinematics and the jet activity produced in the Higgs boson events. The observed spectra are statistically limited but broadly in line with the theoretical expectations

    Part 2: CT characterisation of pancreatic neoplasm: tumour mimics

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    There are numerous pancreatic and peripancreatic conditions that can mimic pancreatic neoplasms. Many of these can be confidently diagnosed on computed tomography (CT), while others will require further imaging. Knowledge of these tumour mimics is important to avoid misclassification of benign conditions as malignant and to avoid unnecessary surgery. Mimics can be grouped as parenchymal, vascular, biliary and peripancreatic. These are discussed and illustrated in this review

    Search for squarks and gluinos in events with isolated leptons, jets and missing transverse momentum at s√=8 TeV with the ATLAS detector

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    The results of a search for supersymmetry in final states containing at least one isolated lepton (electron or muon), jets and large missing transverse momentum with the ATLAS detector at the Large Hadron Collider are reported. The search is based on proton-proton collision data at a centre-of-mass energy s√=8 TeV collected in 2012, corresponding to an integrated luminosity of 20 fb−1. No significant excess above the Standard Model expectation is observed. Limits are set on supersymmetric particle masses for various supersymmetric models. Depending on the model, the search excludes gluino masses up to 1.32 TeV and squark masses up to 840 GeV. Limits are also set on the parameters of a minimal universal extra dimension model, excluding a compactification radius of 1/R c = 950 GeV for a cut-off scale times radius (ΛR c) of approximately 30

    Search for squarks and gluinos with the ATLAS detector in final states with jets and missing transverse momentum using √s=8 TeV proton-proton collision data

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    A search for squarks and gluinos in final states containing high-p T jets, missing transverse momentum and no electrons or muons is presented. The data were recorded in 2012 by the ATLAS experiment in s√=8 TeV proton-proton collisions at the Large Hadron Collider, with a total integrated luminosity of 20.3 fb−1. Results are interpreted in a variety of simplified and specific supersymmetry-breaking models assuming that R-parity is conserved and that the lightest neutralino is the lightest supersymmetric particle. An exclusion limit at the 95% confidence level on the mass of the gluino is set at 1330 GeV for a simplified model incorporating only a gluino and the lightest neutralino. For a simplified model involving the strong production of first- and second-generation squarks, squark masses below 850 GeV (440 GeV) are excluded for a massless lightest neutralino, assuming mass degenerate (single light-flavour) squarks. In mSUGRA/CMSSM models with tan ÎČ = 30, A 0 = −2m 0 and ÎŒ > 0, squarks and gluinos of equal mass are excluded for masses below 1700 GeV. Additional limits are set for non-universal Higgs mass models with gaugino mediation and for simplified models involving the pair production of gluinos, each decaying to a top squark and a top quark, with the top squark decaying to a charm quark and a neutralino. These limits extend the region of supersymmetric parameter space excluded by previous searches with the ATLAS detector

    Evidence for the Higgs-boson Yukawa coupling to tau leptons with the ATLAS detector

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    Results of a search for H → τ τ decays are presented, based on the full set of proton-proton collision data recorded by the ATLAS experiment at the LHC during 2011 and 2012. The data correspond to integrated luminosities of 4.5 fb−1 and 20.3 fb−1 at centre-of-mass energies of √s = 7 TeV and √s = 8 TeV respectively. All combinations of leptonic (τ → `ÎœÎœÂŻ with ` = e, ”) and hadronic (τ → hadrons Îœ) tau decays are considered. An excess of events over the expected background from other Standard Model processes is found with an observed (expected) significance of 4.5 (3.4) standard deviations. This excess provides evidence for the direct coupling of the recently discovered Higgs boson to fermions. The measured signal strength, normalised to the Standard Model expectation, of ” = 1.43 +0.43 −0.37 is consistent with the predicted Yukawa coupling strength in the Standard Model

    Measurement of the top pair production cross section in 8 TeV proton-proton collisions using kinematic information in the lepton plus jets final state with ATLAS

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    A measurement is presented of the ttˉt\bar{t} inclusive production cross-section in pppp collisions at a center-of-mass energy of s=8\sqrt{s}=8 TeV using data collected by the ATLAS detector at the CERN Large Hadron Collider. The measurement was performed in the lepton+jets final state using a data set corresponding to an integrated luminosity of 20.3 fb−1^{-1}. The cross-section was obtained using a likelihood discriminant fit and bb-jet identification was used to improve the signal-to-background ratio. The inclusive ttˉt\bar{t} production cross-section was measured to be 260±1(stat.)−23+22(syst.)±8(lumi.)±4(beam)260\pm 1{\textrm{(stat.)}} ^{+22}_{-23} {\textrm{(syst.)}}\pm 8{\textrm{(lumi.)}}\pm 4{\mathrm{(beam)}} pb assuming a top-quark mass of 172.5 GeV, in good agreement with the theoretical prediction of 253−15+13253^{+13}_{-15} pb. The ttˉ→(e,ÎŒ)+jetst\bar{t}\to (e,\mu)+{\mathrm{jets}} production cross-section in the fiducial region determined by the detector acceptance is also reported.Comment: Published version, 19 pages plus author list (35 pages total), 3 figures, 2 tables, all figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/TOPQ-2013-06
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