Two structures are observed close to the kinematic threshold in the Ξ 0 b π − mass spectrum in a sample of proton-proton collision data, corresponding to an integrated luminosity of 3.0 fb − 1 , ...recorded by the LHCb experiment. In the quark model, two baryonic resonances with quark content b d s are expected in this mass region: the spin-parity J P = ( 1 / 2 ) + and J P = ( 3 / 2 ) + states, denoted Ξ ' − b and Ξ * − b . Interpreting the structures as these resonances, we measure the mass differences and the width of the heavier state to be m ( Ξ ' − b ) − m ( Ξ 0 b ) − m ( π − ) = 3.653 ± 0.018 ± 0.006 MeV / c 2 , m ( Ξ * − b ) − m ( Ξ 0 b ) − m ( π − ) = 23.96 ± 0.12 ± 0.06 MeV / c 2 , Γ ( Ξ * − b ) = 1.65 ± 0.31 ± 0.10 MeV , where the first and second uncertainties are statistical and systematic, respectively. The width of the lighter state is consistent with zero, and we place an upper limit of Γ ( Ξ ' − b ) < 0.08 MeV at 95% confidence level. Relative production rates of these states are also reported.
The B−→D+K−π− decay is observed in a data sample corresponding to 3.0 fb−1 of pp collision data recorded by the LHCb experiment during 2011 and 2012. Its branching fraction is measured to be ...B(B−→D+K−π−)=(7.92±0.23±0.24±0.42)×10−5 where the uncertainties are statistical, systematic and from the branching fraction of the normalisation channel B−→D+π−π−, respectively. An amplitude analysis of the resonant structure of the B−→D+K−π− decay is used to measure the contributions from quasi-two-body B−→D∗0(2400)0K−, B−→D∗2(2460)0K−, and B−→D∗J(2760)0K− decays, as well as from nonresonant sources. The D∗J(2760)0 resonance is determined to have spin~1.
Introduction The influence of adult socioeconomic status, co-habitation, gender, smoking, coffee and alcohol intake on risk of Helicobacter pylori infection is uncertain. Methods Subjects between ...aged 40–49 years were randomly invited to attend their local primary care centre. Participants were interviewed by a researcher on smoking, coffee and alcohol intake, history of living with a partner, present and childhood socioeconomic conditions. Helicobacter pylori status was determined by 13C-urea breath test. Results In all, 32 929 subjects were invited, 8429 (26%) were eligible and 2327 (27.6%) were H. pylori positive. Helicobacter pylori infection was more common in men and this association remained after controlling for childhood and adult risk factors in a logistic regression model (odds ratio OR = 1.15; 95% CI: 1.03–1.29). Living with a partner was also an independent risk factor for infection (OR = 1.30; 95% CI: 1.01–1.67), particularly in partners of lower social class (social class IV and V—OR = 1.47; 95% CI: 1.19–1.81, compared with social class I and II). Helicobacter pylori infection was more common in lower social class groups (I and II—22% infected, III—29% infected, IV and V—38% infected) and there was a significant increase in risk of infection in manual workers compared with non-manual workers after controlling for other risk factors (OR = 1.18; 95% CI: 1.03–1.34). Alcohol and coffee intake were not independent risk factors for infection and smoking was only a risk factor in those smoking >35 cigarettes a day. Conclusions Male gender, living with a partner and poor adult socioeconomic conditions are associated with increased risk of H. pylori infection.
Polymeric foams are used extensively as the core of sandwich structures in automotive and aerospace industries. Normally, several experiments are necessary to obtain the required properties to model ...the response of crushable foams using finite element analysis (FEA). Hence, this research aims to develop a simple and reliable calibration process for extracting the physical parameters which are required by the material model available in the commercial FE package Abaqus. To do this, a set of experimental tests, including uniaxial compression, uniaxial tension and shear punch tests, is proposed. All the experimental tests were also simulated, and generally, good correlations between experiments and numerical models were obtained. The validity of the overall approach was finally demonstrated using an indentation test in which the foam was subjected to a more complex mixed mode loading. During these indentation tests, digital image correlation was used to observe full-field strain distribution in the foam under the indenter. Good agreement between the experimental results and the numerical predictions was found for load–displacement response, failure mode and strain distribution.
Debonding between the skins and the core in a sandwich structure is a critical failure mode in automotive applications; once debonding occurs, the load carrying capacity of a sandwich structure ...drastically decreases. In the present paper, the effect of using three core materials, with different cell characteristics, on the interfacial strength between the foam cores and a CFRP skin is investigated through mechanical testing and numerical modelling. A key finding is that foams with a coarse cellular structure favour a high resin uptake at the interface during the manufacturing process, which results in a stronger interfacial bonding between the foam and the CFRP. During Mode I loading, the thick resin layer at the interface postpones crack initiation and kinking in the core, whilst under Mode II, this resin layer delays the collapse in compression of foam cells under the crack tip. Thus, the importance of including this thick resin layer in the FE modelling was demonstrated. Finally, as the CZM was shown to be unable to predict the unstable crack propagation within the core, an alternative approach has been suggested which has the significant benefit of not requiring experimental testing of the interface between the skin and the core.
Display omitted
•Coarse cell foams favour a high resin uptake at the interface during manufacturing.•Under Mode I loading, this resin layer postpones crack initiation.•Under Mode II loading, it delays the collapse of foam cells under the crack tip.•Importance of including this hybrid layer in FEA is demonstrated for the first time.•A more accurate alternative FEA approach is proposed to model skin-core debonding.
The difference in total widths between the Bc+ and B+ mesons is measured using a data sample corresponding to an integrated luminosity of 3.0 fb−1 collected by the LHCb experiment in 7 and 8 TeV ...centre-of-mass energy proton–proton collisions at the LHC. Through the study of the time evolution of Bc+→J/ψπ+ and B+→J/ψK+ decays, the width difference is measured to beΔΓ≡ΓBc+−ΓB+=4.46±0.14±0.07 mm−1c, where the first uncertainty is statistical and the second systematic. The known lifetime of the B+ meson is used to convert this to a precise measurement of the Bc+ lifetime,τBc+=513.4±11.0±5.7 fs, where the first uncertainty is statistical and the second is systematic.
Summary
Background Screening for Helicobacter pylori reduces dyspepsia and dyspepsia‐related costs in positive individuals.
Aims To assess effect of knowledge of H. pylori status on ...healthcare‐seeking in negative individuals.
Methods H. pylori‐negative subjects in a community screening programme were randomized to placebo triple therapy or informed of their negative H. pylori status. Dyspepsia‐related resource data were extracted from primary care records at 2 years, and National Health Service reference costs were applied to calculate the total cost per subject. Proportions of individuals incurring any cost were compared using a relative risk (RR) and 95% confidence interval (CI). Differences in costs were compared using an independent sample t‐test.
Results A total of 1353 H. pylori‐negative individuals were randomized to placebo whilst 1355 were informed of their infection status. In the placebo arm, 212 (16%) subsequently incurred any dyspepsia‐related cost compared to 172 (13%) informed of their infection status (RR of incurring cost = 0.81; 95% CI: 0.67–0.97). Those informed of their infection status incurred lower costs (mean saving per individual = £11.02; 95% CI: −£3.52 to 25.56).
Conclusions H. pylori‐negative individuals informed of infection status sought health care for dyspepsia less often than those who were unaware. Population screening may reduce dyspepsia‐related costs in uninfected, as well as infected individuals.
Adhesively bonded composite–composite single-lap joints, with cross-ply GFRP adherends, have been cyclically loaded to initiate disbonding at either end of the overlap length. Disbond initiation and ...growth have been monitored using a combination of
in situ photography (the joint is transparent) and a single chirped fibre Bragg grating (CFBG) sensor embedded within one composite adherend (with the low-wavelength end of the sensor adjacent to the cut end) and not in the adhesive bondline. Sensors having the same spectral bandwidth (20
nm) and lengths in the range 15–60
mm have been tested. The experimental results have been modelled using a combination of finite-element analysis and commercial software for predicting FBG spectra, and the predictions are in very good agreement with the experimental results. In all cases, it has been shown that the position of the disbond front can be located using the CFBG sensors with a precision of about 2
mm.
PDF
