Measurement of pi^0 photoproduction on the proton at MAMI C

Differential cross sections for the gamma p -> pi^0 p reaction have been measured with the A2 tagged-photon facilities at the Mainz Microtron, MAMI C, up to the center-of-mass energy W=1.9 GeV. The new results, obtained with a fine energy and angular binning, increase the existing quantity of pi^0 photoproduction data by ~47%. Owing to the unprecedented statistical accuracy and the full angular coverage, the results are sensitive to high partial-wave amplitudes. This is demonstrated by the decomposition of the differential cross sections in terms of Legendre polynomials and by further comparison to model predictions. A new solution of the SAID partial-wave analysis obtained after adding the new data into the fit is presented.Comment: 13 pages, 12 figures, 1 tabl

Helicity-dependent cross sections and double-polarization observable E in η photoproduction from quasifree protons and neutrons

Precise helicity-dependent cross sections and the double-polarization observable E were measured for η photoproduction from quasifree protons and neutrons bound in the deuteron. The η → 2γ and η → 3π0 → 6γ decay modes were used to optimize the statistical quality of the data and to estimate systematic uncertainties. The measurement used the A2 detector setup at the tagged photon beam of the electron accelerator MAMI in Mainz. A longitudinally polarized deuterated butanol target was used in combination with a circularly polarized photon beam from bremsstrahlung of a longitudinally polarized electron beam. The reaction products were detected with the electromagnetic calorimeters Crystal Ball and TAPS, which covered 98% of the full solid angle. The results show that the narrow structure observed earlier in the unpolarized excitation function of η photoproduction off the neutron appears only in reactions with antiparallel photon and nucleon spin (σ1/2). It is absent for reactions with parallel spin orientation (σ3/2) and thus very probably related to partial waves with total spin 1/2. The behavior of the angular distributions of the helicity-dependent cross sections was analyzed by fitting them with Legendre polynomials. The results are in good agreement with a model from the Bonn-Gatchina group, which uses an interference of P11 and S11 partial waves to explain the narrow structure

High-statistics measurement of the η→3π0 decay at the Mainz Microtron

The largest, at the moment, statistics of 7 x 10(6) eta -> 3 pi(0) decays, based on 6.2 x 10(7) eta mesons produced in the gamma p -> eta p reaction, has been accumulated by the A2 Collaboration at the MainzMicrotron, MAMI. It allowed a detailed study of the eta -> 3 pi(0) dynamics beyond its conventional parametrization with just the quadratic slope parameter a and enabled, for the first time, a measurement of the second-order term and a better understanding of the cusp structure in the neutral decay. The present data are also compared to recent theoretical calculations that predict a nonlinear dependence along the quadratic distance from the Dalitz-plot center

Measurement of the π0→e+e-γ Dalitz decay at the Mainz Microtron

The Dalitz decay π0→e+e-γ has been measured in the γp→π0p reaction with the A2 tagged-photon facility at the Mainz Microtron, MAMI. The value obtained for the slope parameter of the π0 electromagnetic transition form factor, aπ=0.030±0.010tot, is in agreement with existing measurements of this decay and with recent theoretical calculations. The uncertainty obtained in the value of aπ is lower than in previous results based on the π0→e+e-γ decay

Individual and population screening of varices needing treatment by a simple, safe and accurate test

Background: Several tests have been developed to screen varices needing treatment (VNT) in different screening settings. We aimed to develop simple estimators to quantify VNT risk and spare endoscopy while missing <5% of VNT, adapted to different screenings in the main etiologies.Methods: 2,368 patients with chronic liver disease were included. The main VNT predictors were platelets, prothrombin index (PI) and LSM. Their interactions led to score construction, LIP: (LSM*45)/(PI*platelets), and BLIP: BMI-adjusted LIP in NAFLD. Scores were categorized either for population (VNT sensitivity >= 95%) or individual (negative predictive value >95%) VNT screening.Results: 1) Scores diagnosing VNT. AUROCs were, PLER: 0.767 Anticipate: 0.773 (p=0.059 vs pre-vious), LIP: 0.779 (p=0.136), PLEASE: 0.789 (p=0.196). 2) Population screening performance was in increasing order (with missed VNT rate), Baveno6 criteria: 23.9% (2.5%), Anticipate: 24.5%, p=0.367 vs previous (3.3%), PLER: 27.3%, p<0.001 (3.6%), LIP: 33.4%, p<0.001 (4.2%), PLEASE: 35.2%, p=0.006 (3.6%). In NAFLD, LIP: 38.6%, BLIP: 40.8%, p=0.038. 3) Individual screening per-formance was, expanded Baveno6 criteria: 42.7%, LIP: 54.1%, p<0.001. In NAFLD, performance was, NAFLD-cirrhosis criteria: 66.7%, BLIP: 74.6%, p<0.001.Conclusion: LIP combined simplicity, performance and safety in each etiology. In NAFLD, BMI-adjusted LIP outperformed other tests.(c) 2023 Elsevier Masson SAS. All rights reserved

Effect of orally administered NDGA on liver weights (A) and triglyceride content (B) in high-fructose fed (HFrD) hypertriglyceridemic rats.

<p>Groups of rats were maintained on a chow-diet (n = 4) or HFrD (n = 12) for 8 weeks and, subsequently, HFrD fed rats were divided into two groups: one was orally gavaged with NDGA (n = 6) at a dose of 125 mg/kg BW twice a day for 5 days and the other group received vehicle (n = 6) (control). Liver samples were subsequently weighed (A) and quantified for TG content (B), as described in the Materials and Methods. Values are mean ± SE. * <i>P</i><0.05; ** <i>P<0</i>.<i>01</i>; *** <i>P<0</i>.<i>001</i>. Raw data and statistics are listed in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0138203#pone.0138203.s001" target="_blank">S1 Dataset</a>.</p

Study of eta and eta' photoproduction at MAMI

Published VersionThe reactions &gamma;p&rarr;&eta;p and &gamma;p&rarr;&eta;&prime;p are measured from their thresholds up to the center-of-mass energy W=1.96&thinsp;&thinsp;GeV with the tagged-photon facilities at the Mainz Microtron, MAMI. Differential cross sections are obtained with unprecedented statistical accuracy, providing fine energy binning and full production-angle coverage. A strong cusp is observed in the total cross section for &eta; photoproduction at the energies in the vicinity of the &eta;&prime; threshold, W=1896&thinsp;&thinsp;MeV (E&gamma;=1447&thinsp;&thinsp;MeV). Within the framework of a revised &eta;MAID isobar model, the cusp, in connection with a steep rise of the &eta;&prime; total cross section from its threshold, can only be explained by a strong coupling of the poorly known N(1895)1/2&minus; state to both &eta;p and &eta;&prime;p. Including the new high-accuracy results in the &eta;MAID fit to available &eta; and &eta;&prime; photo production data allows the determination of the N(1895)1/2&minus; properties

Cover & Contents

The double polarization observable E and the helicity dependent cross sections σ1/2 and σ3/2 were measured for η photoproduction from quasifree protons and neutrons. The circularly polarized tagged photon beam of the A2 experiment at the Mainz MAMI accelerator was used in combination with a longitudinally polarized deuterated butanol target. The almost 4π detector setup of the Crystal Ball and TAPS is ideally suited to detect the recoil nucleons and the decay photons from η→2γ and η→3π0. The results show that the narrow structure previously observed in η photoproduction from the neutron is only apparent in σ1/2 and hence, most likely related to a spin-1/2 amplitude. Nucleon resonances that contribute to this partial wave in η production are only N 1/2- (S11) and N 1/2+ (P11). Furthermore, the extracted Legendre coefficients of the angular distributions for σ1/2 are in good agreement with recent reaction model predictions assuming a narrow resonance in the P11 wave as the origin of this structure

Measurement of the ω → π 0 e + e − and η → e + e − γ Dalitz decays with the A2 setup at the Mainz Microtron

The Dalitz decays η→e+e−γ and ω→π0e+e− have been measured in the γp→ηp and γp→ωp reactions, respectively, with the A2 tagged-photon facility at the Mainz Microtron. The value obtained for the slope parameter of the electromagnetic transition form factor of η, Λ−2η=(1.97±0.11tot)GeV−2, is in good agreement with previous measurements of the η→e+e−γ and η→μ+μ−γ decays. The uncertainty obtained in the value of Λ−2η is lower than in previous results based on the η→e+e−γ decay. The value obtained for the ω slope parameter, Λ−2ωπ0=(1.99±0.21tot)GeV−2, is somewhat lower than previous measurements based on ω→π0μ+μ−, but the results for the ω transition form factor are in better agreement with theoretical calculations, compared to earlier experiments