111 research outputs found
Heterozygous prothrombin 20210G-A mutation, associated with hyperhomocysteinemia, and homozygous methylenetetrahydrofolate reductase 677C-T mutation, in a patient with portal and mesenteric venous thrombosis
No full textWe herein report a 34-year-old man who was investigated for severe abdominal pain. Portal vein thrombosis (PVT) and mesenteric vein thrombosis (MVT) were diagnosed. An association with two predisposing factors for thrombosis was noted: (1) heterozygous factor II 20210G-A mutation and (2) homozygous methylenetetrahydrofolate reductase (MTHFR) 677C-T mutation with hyperhomocysteinemia. Our case is of particular interest because the patient reported herein, is homozygote for the MTHFR 677C-T mutation, while the only two other cases reported in the literature with similar gene mutations, were heterozygotes for the mutation. © 2004 The European Hematology Association All rights reserved.ALKARAWI MA, 1990, HEPATO-GASTROENTEROL, V37, P507; BLUM U, 1995, RADIOLOGY, V195, P153; Brown K, 1998, BRIT J HAEMATOL, V103, P42, DOI 10.1046-j.1365-2141.1998.00935.x; Chamouard P, 1999, GASTROENTEROLOGY, V116, P144, DOI 10.1016-S0016-5085(99)70238-6; Deloughery TG, 1996, CIRCULATION, V94, P3074; denHeijer M, 1996, NEW ENGL J MED, V334, P759, DOI 10.1056-NEJM199603213341203; De Stefano V, 2000, SEMIN THROMB HEMOST, V26, P305, DOI 10.1055-s-2000-8473; FALCON CR, 1994, ARTERIOSCLER THROMB, V14, P1080; Hainaut P, 2002, THROMB RES, V106, P121, DOI 10.1016-S0049-3848(02)00096-8; Lee R, 2003, HEMATOL ONCOL CLIN N, V17, P85, DOI 10.1016-S0889-8588(02)00090-4; Marie I, 2000, GASTROENTEROLOGY, V118, P237, DOI 10.1016-S0016-5085(00)70442-2; Ocal IT, 1997, MOL DIAGN, V2, P61, DOI 10.1016-S1084-8592(97)80012-4; Ridker PM, 1997, CIRCULATION, V95, P1777; Silingardi M, 2000, THROMB HAEMOSTASIS, V84, P358; Souto JC, 1998, THROMB HAEMOSTASIS, V80, P366; Taher A, 2001, THROMB HAEMOSTASIS, V86, P723107
Duodenal mucosa-associated lymphoid tissue lymphoma successfully treated by radiation therapy
No full textDuodenal mucosa-associated lymphoid tissue (MALT) lymphoma is very rare, and little is known about its clinical characteristics, endoscopic and endosonographic features, and treatment. We hereby report a case of duodenal MALT lymphoma successfully treated by radiation therapy (RT). The patient was referred to us with epigastric pain and positive fecal occult blood testing. His symptoms failed to resolve with eradication therapy for a Helicobacter pylori infection that was diagnosed by a gastric biopsy performed elsewhere. Endoscopy at our institution revealed hypertophy of the duodenal folds with erosions involving a third of the circumference few centimeters beyond the ampulla of Vater. Histopathologic and immunophenotypic features were consistent with a MALT lymphoma. There was no evidence of a H. pylori infection by gastric biopsy and urea breath test. Computed tomography scan of the abdomen and pelvis was normal. Endoscopic ultrasound showed thickening of the duodenal wall and hypoechoic infiltration into the submucosal layer. The patient was treated with RT with a complete response. Two and a half years later, he remains in complete clinical, endoscopic, and histopathologic remission. This case illustrates the importance of RT in patients with duodenal MALT lymphoma whose disease did not respond to H. pylori eradication. Copyright Clearance Center.Chaudhary N, 2006, DIGEST DIS SCI, V51, P775, DOI 10.1007-s10620-006-3205-0; Inagaki H, 2004, AM J SURG PATHOL, V28, P1560, DOI 10.1097-00000478-200412000-00003; Kawai T, 1998, J GASTROENTEROL, V33, P97, DOI 10.1007-s005350050051; Kim JS, 1999, SCAND J GASTROENTERO, V34, P215; Leone N, 2002, EUR J GASTROEN HEPAT, V14, P893, DOI 10.1097-00042737-200208000-00016; Lepicard A, 2000, AM J GASTROENTEROL, V95, P536; Martinelli G, 2005, J CLIN ONCOL, V23, P1979, DOI 10.1200-JCO.2005.08.128; Nagashima R, 1996, GASTROENTEROLOGY, V111, P1674, DOI 10.1016-S0016-5085(96)70032-X; Nakamura S, 2000, CANCER, V88, P286, DOI 10.1002-(SICI)1097-0142(20000115)88:2286::AID-CNCR73.0.CO;2-Z; Nakamura S, 2001, GASTROINTEST ENDOSC, V54, P772, DOI 10.1067-mge.2001.119602; Ochi M, 2006, SCAND J GASTROENTERO, V41, P365, DOI 10.1080-00365520500331224; Ohtsuka T, 1999, SURG TODAY, V29, P557; Patel VG, 2004, AM SURGEON, V70, P613; Raderer M, 2003, ONCOLOGY-BASEL, V65, P306, DOI 10.1159-000074641; Schechter NR, 1998, J CLIN ONCOL, V16, P1916; Toshima M, 1999, INTERNAL MED, V38, P957, DOI 10.2169-internalmedicine.38.957; Tsang RW, 2001, INT J RADIAT ONCOL, V50, P1258, DOI 10.1016-S0360-3016(01)01549-8; WANG HH, 1995, GASTROINTEST ENDOSC, V41, P258, DOI 10.1016-S0016-5107(95)70352-7; XIANG Z, 2004, HEPATO-GASTROENTEROL, V5, P73212
An implementation of neural simulation-based inference for parameter estimation in ATLAS
No full textNeural simulation-based inference (NSBI) is a powerful class of machine-learning-based methods for statistical inference that naturally handles high-dimensional parameter estimation without the need to bin data into low-dimensional summary histograms. Such methods are promising for a range of measurements, including at the Large Hadron Collider, where no single observable may be optimal to scan over the entire theoretical phase space under consideration, or where binning data into histograms could result in a loss of sensitivity. This work develops a NSBI framework for statistical inference, using neural networks to estimate probability density ratios, which enables the application to a full-scale analysis. It incorporates a large number of systematic uncertainties, quantifies the uncertainty due to the finite number of events in training samples, develops a method to construct confidence intervals, and demonstrates a series of intermediate diagnostic checks that can be performed to validate the robustness of the method. As an example, the power and feasibility of the method are assessed on simulated data for a simplified version of an off-shell Higgs boson couplings measurement in the four-lepton final states. This approach represents an extension to the standard statistical methodology used by the experiments at the Large Hadron Collider, and can benefit many physics analyses
Measurement of the top-quark pole mass in dileptonic events at TeV with the ATLAS experiment
No full textA measurement of the top-quark pole mass is presented in ~events with an additional jet, , produced in collisions at TeV. The data sample, recorded with the ATLAS experiment during Run 2 of the LHC, corresponds to an integrated luminosity of 140 . Events with one electron and one muon of opposite electric charge in the final state are selected to measure the differential cross-section as a function of the inverse of the invariant mass of the system. Iterative Bayesian Unfolding is used to correct the data to enable comparison with fixed-order calculations at next-to-leading-order accuracy in the strong coupling. The process (), where top quarks are taken as stable particles, and the process (), which includes top-quark decays to the dilepton final state and off-shell effects, are considered. The top-quark mass is extracted using a fit of the unfolded normalized differential cross-section distribution. The results obtained with the and calculations are compatible within theoretical uncertainties, providing an important consistency check. The more precise determination is obtained for the measurement: GeV, which is in good agreement with other top-quark mass results.A measurement of the top-quark pole mass is presented in events with an additional jet, + 1-jet, produced in pp collisions at TeV. The data sample, recorded with the ATLAS experiment during Run 2 of the LHC, corresponds to an integrated luminosity of 140 fb. Events with one electron and one muon of opposite electric charge in the final state are selected to measure the + 1-jet differential cross-section as a function of the inverse of the invariant mass of the + 1-jet system. Iterative Bayesian Unfolding is used to correct the data to enable comparison with fixed-order calculations at next-to-leading-order accuracy in the strong coupling. The process , where top quarks are taken as stable particles, and the process , which includes top-quark decays to the dilepton final state and off-shell effects, are considered. The top-quark mass is extracted using a χ fit of the unfolded normalized differential cross-section distribution. The results obtained with the 2 → 3 and 2 → 7 calculations are compatible within theoretical uncertainties, providing an important consistency check. The more precise determination is obtained for the 2 → 3 measurement: GeV, which is in good agreement with other top-quark mass results.[graphic not available: see fulltext]A measurement of the top-quark pole mass is presented in events with an additional jet, , produced in collisions at TeV. The data sample, recorded with the ATLAS experiment during Run 2 of the LHC, corresponds to an integrated luminosity of . Events with one electron and one muon of opposite electric charge in the final state are selected to measure the differential cross-section as a function of the inverse of the invariant mass of the system. Iterative Bayesian Unfolding is used to correct the data to enable comparison with fixed-order calculations at next-to-leading-order accuracy in the strong coupling. The process (), where top quarks are taken as stable particles, and the process (), which includes top-quark decays to the dilepton final state and off-shell effects, are considered. The top-quark mass is extracted using a fit of the unfolded normalized differential cross-section distribution. The results obtained with the and calculations are compatible within theoretical uncertainties, providing an important consistency check. The more precise determination is obtained for the measurement: which is in good agreement with other top-quark mass results
Probing the Higgs boson CP properties in vector-boson fusion production in the channel with the ATLAS detector
No full textThe CP properties of the Higgs boson are studied in the vector-boson fusion production mode. The analysis exploits the decay mode of the Higgs boson into two -leptons using 140 fb of proton-proton collision data at TeV collected by the ATLAS experiment at the Large Hadron Collider. Results are obtained using the Optimal Observable method. CP-violating interactions between the Higgs boson and electroweak gauge bosons are considered in the effective field theory framework, with the interaction strength described in the HISZ basis by , and in the Warsaw basis by , , and . No deviations relative to the Standard Model are observed, and limits are obtained on the strength parameters. The parameter is constrained to the interval [] at the 95% confidence level while is constrained to [], when considering both linear and quadratic effects of physics beyond the Standard Model.The CP properties of the Higgs boson are studied in the vector-boson fusion production mode. The analysis exploits the decay mode of the Higgs boson into two τ-leptons using 140 fb of proton-proton collision data at TeV collected by the ATLAS experiment at the Large Hadron Collider. Results are obtained using the Optimal Observable method. CP-violating interactions between the Higgs boson and electroweak gauge bosons are considered in the effective field theory framework, with the interaction strength described in the HISZ basis by , and in the Warsaw basis by , , and . No deviations relative to the Standard Model are observed, and limits are obtained on the strength parameters. The parameter is constrained to the interval [−0.012, 0.044] at the 95% confidence level while is constrained to [−0.24, 0.83], when considering both linear and quadratic effects of physics beyond the Standard Model.[graphic not available: see fulltext]The CP properties of the Higgs boson are studied in the vector-boson fusion production mode. The analysis exploits the decay mode of the Higgs boson into two -leptons using 140 fb of proton-proton collision data at TeV collected by the ATLAS experiment at the Large Hadron Collider. Results are obtained using the Optimal Observable method. CP-violating interactions between the Higgs boson and electroweak gauge bosons are considered in the effective field theory framework, with the interaction strength described in the HISZ basis by , and in the Warsaw basis by , , and . No deviations relative to the Standard Model are observed, and limits are obtained on the strength parameters. The parameter is constrained to the interval [] at the 95% confidence level while is constrained to [], when considering both linear and quadratic effects of physics beyond the Standard Model
Beam-induced backgrounds measured in the ATLAS detector during local gas injection into the LHC beam vacuum
No full textInelastic beam-gas collisions at the Large Hadron Collider (LHC), within a few hundred metres of the ATLAS experiment, are known to give the dominant contribution to beam backgrounds. These are monitored by ATLAS with a dedicated Beam Conditions Monitor (BCM) and with the rate of fake jets in the calorimeters. These two methods are complementary since the BCM probes backgrounds just around the beam pipe while fake jets are observed at radii of up to several metres. In order to quantify the correlation between the residual gas density in the LHC beam vacuum and the experimental backgrounds recorded by ATLAS, several dedicated tests were performed during LHC Run 2. Local pressure bumps, with a gas density several orders of magnitude higher than during normal operation, were introduced at different locations. The changes of beam-related backgrounds, seen in ATLAS, are correlated with the local pressure variation. In addition the rates of beam-gas events are estimated from the pressure measurements and pressure bump profiles obtained from calculations. Using these rates, the efficiency of the ATLAS beam background monitors to detect beam-gas events is derived as a function of distance from the interaction point. These efficiencies and characteristic distributions of fake jets from the beam backgrounds are found to be in good agreement with results of beam-gas simulations performed with theFluka Monte Carlo programme
A measurement of the high-mass production cross-section at TeV with the ATLAS detector and constraints on new particles and couplings
No full textThe production cross-section of high-mass -lepton pairs is measured as a function of the dilepton visible invariant mass, using 140 fb of TeV proton-proton collision data recorded with the ATLAS detector at the Large Hadron Collider. The measurement agrees with the predictions of the Standard Model. A fit to the invariant mass distribution is performed as a function of -jet multiplicity, to constrain the non-resonant production of new particles described by an effective field theory or in models containing leptoquarks or bosons that couple preferentially to third-generation fermions. The constraints on new particles improve on previous results, and the constraints on effective operators include those affecting the anomalous magnetic moment of the -lepton.The production cross-section of high-mass τ-lepton pairs is measured as a function of the dilepton visible invariant mass, using 140 fb of TeV proton-proton collision data recorded with the ATLAS detector at the Large Hadron Collider. The measurement agrees with the predictions of the Standard Model. A fit to the invariant mass distribution is performed as a function of b-jet multiplicity, to constrain the non-resonant production of new particles described by an effective field theory or in models containing leptoquarks or Z′ bosons that couple preferentially to third-generation fermions. The constraints on new particles improve on previous results, and the constraints on effective operators include those affecting the anomalous magnetic moment of the τ-lepton.[graphic not available: see fulltext]The production cross-section of high-mass -lepton pairs is measured as a function of the dilepton visible invariant mass, using 140 fb of TeV proton-proton collision data recorded with the ATLAS detector at the Large Hadron Collider. The measurement agrees with the predictions of the Standard Model. A fit to the invariant mass distribution is performed as a function of -jet multiplicity, to constrain the non-resonant production of new particles described by an effective field theory or in models containing leptoquarks or bosons that couple preferentially to third-generation fermions. The constraints on new particles improve on previous results, and the constraints on effective operators include those affecting the anomalous magnetic moment of the -lepton
Search for a new pseudoscalar decaying into a pair of bottom and antibottom quarks in top-associated production in =13 TeV proton–proton collisions with the ATLAS detector
No full textA search for a pseudoscalar produced in association with a top-quark pair, or in association with a single top quark plus a boson, with the pseudoscalar decaying into -quarks (), is performed using the full Run 2 data sample using a dileptonic decay mode signature. The search covers pseudoscalar boson masses between 12-100 GeV and involves both the kinematic regime where the decay products of the pseudoscalar are reconstructed as two standard -tagged small-radius jets, or merged into a large-radius jet due to its Lorentz boost. No significant excess relative to expectations is observed. Assuming a branching ratio BR()=100%, the range of pseudoscalar masses between 50 and 80 GeV is excluded at 95% confidence level for a coupling of the pseudoscalar to the top quark of 0.5, while a coupling of 1.0 is excluded at 95% confidence level for the masses considered, with the coupling defined as the strength modifier of the Standard Model Yukawa coupling.A search for a pseudoscalar produced in association with a top-quark pair, or in association with a single top quark plus a boson, with the pseudoscalar decaying into b-quarks (), is performed using the full Run 2 data sample using a dileptonic decay mode signature. The search covers pseudoscalar boson masses between 12 and 100 GeV and involves both the kinematic regime where the decay products of the pseudoscalar are reconstructed as two standard -tagged small-radius jets, or merged into a large-radius jet due to its Lorentz boost. No significant excess relative to expectations is observed. Assuming a branching ratio , the range of pseudoscalar masses between 50 and 80 GeV is excluded at 95% confidence level for a coupling of the pseudoscalar to the top quark of 0.5, while a coupling of 1.0 is excluded at 95% confidence level for the masses considered, with the coupling defined as the strength modifier of the Standard Model Yukawa coupling.A search for a pseudoscalar produced in association with a top-quark pair, or in association with a single top quark plus a boson, with the pseudoscalar decaying into -quarks (), is performed using the full Run 2 data sample using a dileptonic decay mode signature. The search covers pseudoscalar boson masses between 12-100 GeV and involves both the kinematic regime where the decay products of the pseudoscalar are reconstructed as two standard -tagged small-radius jets, or merged into a large-radius jet due to its Lorentz boost. No significant excess relative to expectations is observed. Assuming a branching ratio BR()=100%, the range of pseudoscalar masses between 50 and 80 GeV is excluded at 95% confidence level for a coupling of the pseudoscalar to the top quark of 0.5, while a coupling of 1.0 is excluded at 95% confidence level for the masses considered, with the coupling defined as the strength modifier of the Standard Model Yukawa coupling
Measurement of double-differential charged-current Drell-Yan cross-sections at high transverse masses in collisions at 13 TeV with the ATLAS detector
No full textThis paper presents a first measurement of the cross-section for the charged-current Drell-Yan process above the resonance region, where is an electron or muon. The measurement is performed for transverse masses, , between 200 GeV and 5000 GeV, using a sample of 140 fb of collision data at a centre-of-mass energy of = 13 TeV collected by the ATLAS detector at the LHC during 2015-2018. The data are presented single differentially in transverse mass and double differentially in transverse mass and absolute lepton pseudorapidity. A test of lepton flavour universality shows no significant deviations from the Standard Model. The electron and muon channel measurements are combined to achieve a total experimental precision of 3% at low . The single- and double differential -boson charge asymmetries are evaluated from the measurements. A comparison to next-to-next-to-leading-order perturbative QCD predictions using several recent parton distribution functions and including next-to-leading-order electroweak effects indicates the potential of the data to constrain parton distribution functions. The data are also used to constrain four fermion operators in the Standard Model Effective Field Theory formalism, in particular the lepton-quark operator Wilson coefficient This paper presents a first measurement of the cross-section for the charged-current Drell-Yan process pp → W → ℓν above the resonance region, where ℓ is an electron or muon. The measurement is performed for transverse masses, , between 200 GeV and 5000 GeV, using a sample of 140 fb of pp collision data at a centre-of-mass energy of = 13 TeV collected by the ATLAS detector at the LHC during 2015–2018. The data are presented single differentially in transverse mass and double differentially in transverse mass and absolute lepton pseudorapidity. A test of lepton flavour universality shows no significant deviations from the Standard Model. The electron and muon channel measurements are combined to achieve a total experimental precision of 3% at low . The single- and double differential W-boson charge asymmetries are evaluated from the measurements. A comparison to next-to-next-to-leading-order perturbative QCD predictions using several recent parton distribution functions and including next-to-leading-order electroweak effects indicates the potential of the data to constrain parton distribution functions. The data are also used to constrain four fermion operators in the Standard Model Effective Field Theory formalism, in particular the lepton-quark operator Wilson coefficient .[graphic not available: see fulltext]This paper presents a first measurement of the cross-section for the charged-current Drell-Yan process above the resonance region, where is an electron or muon. The measurement is performed for transverse masses, , between 200 GeV and 5000 GeV, using a sample of 140 fb of collision data at a centre-of-mass energy of = 13 TeV collected by the ATLAS detector at the LHC during 2015-2018. The data are presented single differentially in transverse mass and double differentially in transverse mass and absolute lepton pseudorapidity. A test of lepton flavour universality shows no significant deviations from the Standard Model. The electron and muon channel measurements are combined to achieve a total experimental precision of 3% at low . The single- and double differential -boson charge asymmetries are evaluated from the measurements. A comparison to next-to-next-to-leading-order perturbative QCD predictions using several recent parton distribution functions and including next-to-leading-order electroweak effects indicates the potential of the data to constrain parton distribution functions. The data are also used to constrain four fermion operators in the Standard Model Effective Field Theory formalism, in particular the lepton-quark operator Wilson coefficient $c_{\ell q}^{(3)}.
Charged-hadron and identified-hadron (K0 S, , −) yield measurements in photonuclear Pb+Pband p+Pbcollisions at √ sNN = 5.02TeV with ATLAS
No full textThis paper presents the measurement of charged-hadron and identified-hadron (K0 S, , −) yields in photonuclear collisions using 1.7nb−1 of √ sNN = 5.02TeV Pb+Pb data collected in 2018 with the ATLAS detector at the Large Hadron Collider. Candidate photonuclear events are selected using a combination of tracking and calorimeter information, including the zero-degree calorimeter. The yields as a function of transverse momentum and rapidity are measured in these photonuclear collisions as a function of charged-particle multiplicity. These photonuclear results are compared with 0.1nb−1 of √ sNN = 5.02TeV p+Pbdata collected in 2016 by ATLAS using similar charged-particle multiplicity selections. These photonuclear measurements shed light on potential quark-gluon plasma formation in photonuclear collisions via observables sensitive to radial flow, enhanced baryon-to-meson ratios, and strangeness enhancement. The results are also compared with the Monte Carlo DPMJET-III generator and hydrodynamic calculations to test whether such photonuclear collisions may produce small droplets of quark-gluon plasma that flow collectively
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