Sneha Malde

Abstract:

Water as an intraluminal negative contrast medium produces improved image quality with reduced artefact. However, rapid absorption of oral water in the bowel relative to speed and timing of image capturing has limited its clinical application. These findings predate advances in multidetector-row computed tomography (CT). To re-evaluate differences in image quality, we studied image clarity and luminal distention between the same group of patients who received both a pancreas protocol CT (PPCT) that uses oral water and a conventional positive oral contrast scan. We reviewed 66 patients who had previously undergone both a PPCT and an oral contrast abdominal CT. CT images were independently reviewed by two board-certified radiologists who scored degree of hollow viscus distention and visualization of mural detail using a Likert 5-point scale. Results were evaluated by using the Wilcoxon-signed rank test. Student's t test was applied to evaluate the differences in radiation dosage and Spearman's correlational test was used to evaluate interrater correlation between the radiologists. In comparing the mean radiation dosage, there was no statistical difference between the two protocols, and there was good interrater association with ratios of 0.595 and 0.51 achieved for the PPCT and conventional oral scan, respectively. The Wilcoxon signed-rank test showed statistical differences in the stomach (P < 0.001) for both clarity (P < 0.001) and distention (P < 0.001), the duodenum for both clarity (P < 0.001) and distention (P = 0.02), and the ileum for distention (P = 0.02) with the PPCT having a better median score for organ clarity in the stomach and duodenum and better luminal distention in the stomach, equal distention in the duodenum, and slightly worse distention in the ileum. For the remainder of the bowel and organs evaluated, there was no statistically significant difference in the ratings between the two protocols. Using present CT scan technology, water can be an effective contrast medium causing better or equal distention in the bowel and better or equal clarity than routine barium contrast. This calls for a need to reconsider the use of water as a contrast medium in clinical practice.

Abstract:

The decays Bc+→J/ψDs+ and Bc+→J/ψDs*+ are observed for the first time using a dataset, corresponding to an integrated luminosity of 3 fb-1, collected by the LHCb experiment in proton-proton collisions at center-of-mass energies of √s=7 and 8 TeV. The statistical significance for both signals is in excess of 9 standard deviations. The following ratios of branching fractions are measured to be B(Bc+→J/ ψDs+)B(Bc+→J/ψπ+)=2.90±0.57±0.24, B(Bc+→J/ψDs*+)B(Bc+→J/ψDs+)=2.37±0.56±0. 10, where the first uncertainties are statistical and the second systematic. The mass of the Bc+ meson is measured to be mBc+=6276.28±1. 44(stat)±0.36(syst) MeV/c2, using the Bc+→J/ψDs+ decay mode. © 2013 CERN.

Abstract:

The time-dependent CP asymmetry in Bs0→J/ψK+K - decays is measured using pp collision data at √s=7 TeV, corresponding to an integrated luminosity of 1.0 fb-1, collected with the LHCb detector. The decay-time distribution is characterized by the decay widths ΓL and ΓH of the light and heavy mass eigenstates of the Bs0-B̄s0 system and by a CP-violating phase s. In a sample of 27 617 Bs0→J/ψK+K- decays, where the dominant contribution comes from Bs0→J/ψ decays, these parameters are measured to be s=0.07±0.09(stat) ±0.01(syst) rad, Γs≡(ΓL+Γ H)/2=0.663±0.005(stat)±0.006(syst) ps-1, and ΔΓs≡ΓL-ΓH=0. 100±0.016(stat)±0.003(syst) ps-1, corresponding to the single most precise determination of s, ΔΓs, and Γs. The result of performing a combined analysis with Bs0→J/ψπ+π- decays gives s=0.01±0.07(stat)±0.01(syst) rad, Γs= 0.661±0.004(stat)±0.006(syst) ps-1, and ΔΓs=0.106±0.011(stat)±0.007(syst) ps -1. All measurements are in agreement with the Standard Model predictions. © 2013 CERN. Published by the American Physical Society under the terms of the http://creativecommons.org/licenses/by/3.0/ Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

Abstract:

First observations of the BS0→ψ(2S)η, B0→ψ(2S)π+π- and BS0→ψ(2S)π+π- decays are made using a dataset corresponding to an integrated luminosity of 1.0 fb-1 collected by the LHCb experiment in proton-proton collisions at a centre-of-mass energy of √s=7 TeV. The ratios of the branching fractions of each of the ψ(2S) modes with respect to the corresponding J/ψ decays are where the third uncertainty corresponds to the uncertainties of the dilepton branching fractions of the J/ψ and ψ(2S) meson decays. © 2013 CERN.

Abstract:

The first observation of the decay Bs0→D̄0K -π+ is reported. The analysis is based on a data sample, corresponding to an integrated luminosity of 1.0 fb-1 of pp collisions, collected with the LHCb detector. The branching fraction relative to that of the topologically similar decay B0→D̄0π +π- is measured to be B(Bs0→D ̄0K-π+)B(B0→D ̄0π+π-)=1.18±0.05(stat) ±0.12(syst). In addition, the relative branching fraction of the decay B0→D̄0K+π- is measured to be B(B0→D̄0K+π-)B(B0→D ̄0π+π-)=0.106±0.007(stat) ±0.008(syst). © 2013 CERN. Published by the American Physical Society under the terms of the http://creativecommons.org/licenses/by/3.0/ Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.