915 research outputs found

    Charmonium properties from lattice QCD + QED: hyperfine splitting, J/ψJ/\psi leptonic width, charm quark mass and aμca_{\mu}^c

    Get PDF
    We have performed the first nf=2+1+1n_f = 2+1+1 lattice QCD computations of the properties (masses and decay constants) of ground-state charmonium mesons. Our calculation uses the HISQ action to generate quark-line connected two-point correlation functions on MILC gluon field configurations that include u/du/d quark masses going down to the physical point, tuning the cc quark mass from MJ/ψM_{J/\psi} and including the effect of the cc quark's electric charge through quenched QED. We obtain MJ/ψMηcM_{J/\psi}-M_{\eta_c} (connected) = 120.3(1.1) MeV and interpret the difference with experiment as the impact on MηcM_{\eta_c} of its decay to gluons, missing from the lattice calculation. This allows us to determine ΔMηcannihiln\Delta M_{\eta_c}^{\mathrm{annihiln}} =+7.3(1.2) MeV, giving its value for the first time. Our result of fJ/ψ=f_{J/\psi}= 0.4104(17) GeV, gives Γ(J/ψe+e)\Gamma(J/\psi \rightarrow e^+e^-)=5.637(49) keV, in agreement with, but now more accurate than experiment. At the same time we have improved the determination of the cc quark mass, including the impact of quenched QED to give mc(3GeV)\overline{m}_c(3\,\mathrm{GeV}) = 0.9841(51) GeV. We have also used the time-moments of the vector charmonium current-current correlators to improve the lattice QCD result for the cc quark HVP contribution to the anomalous magnetic moment of the muon. We obtain aμc=14.638(47)×1010a_{\mu}^c = 14.638(47) \times 10^{-10}, which is 2.5σ\sigma higher than the value derived using moments extracted from some sets of experimental data on R(e+ehadrons)R(e^+e^- \rightarrow \mathrm{hadrons}). This value for aμca_{\mu}^c includes our determination of the effect of QED on this quantity, δaμc=0.0313(28)×1010\delta a_{\mu}^c = 0.0313(28) \times 10^{-10}.Comment: Added extra discussion on QED setup, some new results to study the effects of strong isospin breaking in the sea (including new Fig. 1) and a fit stability plot for the hyperfine splitting (new Fig. 7). Version accepted for publication in PR

    BKB_K using HYP-smeared staggered fermions in Nf=2+1N_f=2+1 unquenched QCD

    Full text link
    We present results for kaon mixing parameter BKB_K calculated using HYP-smeared improved staggered fermions on the MILC asqtad lattices. We use three lattice spacings (a0.12a\approx 0.12, 0.090.09 and 0.06  0.06\;fm), ten different valence quark masses (mms/10msm\approx m_s/10-m_s), and several light sea-quark masses in order to control the continuum and chiral extrapolations. We derive the next-to-leading order staggered chiral perturbation theory (SChPT) results necessary to fit our data, and use these results to do extrapolations based both on SU(2) and SU(3) SChPT. The SU(2) fitting is particularly straightforward because parameters related to taste-breaking and matching errors appear only at next-to-next-to-leading order. We match to the continuum renormalization scheme (NDR) using one-loop perturbation theory. Our final result is from the SU(2) analysis, with the SU(3) result providing a (less accurate) cross check. We find BK(NDR,μ=2GeV)=0.529±0.009±0.032B_K(\text{NDR}, \mu = 2 \text{GeV}) = 0.529 \pm 0.009 \pm 0.032 and B^K=BK(RGI)=0.724±0.012±0.043\hat{B}_K =B_K(\text{RGI})= 0.724 \pm 0.012 \pm 0.043, where the first error is statistical and the second systematic. The error is dominated by the truncation error in the matching factor. Our results are consistent with those obtained using valence domain-wall fermions on lattices generated with asqtad or domain-wall sea quarks.Comment: 37 pages, 31 figures, most updated versio

    Short term outcomes of total arterial coronary revascularization in patients above 65 years: a propensity score analysis

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>Despite the advantages of bilateral mammary coronary revascularization, many surgeons are still restricting this technique to the young patients. The objective of this study is to demonstrate the safety and potential advantages of bilateral mammary coronary revascularization in patients older than 65 years.</p> <p>Methods</p> <p>Group I included 415 patients older than 65 years with exclusively bilateral mammary revascularization. Using a propensity score we selected 389 patients (group II) in whom coronary bypass operations were performed using the left internal mammary artery and the great saphenous vein.</p> <p>Results</p> <p>The incidence of postoperative stroke was higher in group II (1.5% vs. 0%, P = 0.0111). The amount of postoperative blood loss was higher in group I (908 ± 757 ml vs. 800 ± 713 ml, P = 0.0405). There were no other postoperative differences between both groups.</p> <p>Conclusion</p> <p>Bilateral internal mammary artery revascularization can be safely performed in patients older than 65 years. T-graft configuration without aortic anastomosis is particularly beneficial in this age group since it avoids aortic manipulation, which is an important risk factor for postoperative stroke.</p

    Process evaluation results from a school- and community-linked intervention: the Trial of Activity for Adolescent Girls (TAAG)

    Get PDF
    Process evaluation is a component of intervention research that evaluates whether interventions are delivered and received as intended. Here, we describe the process evaluation results for the Trial of Activity for Adolescent Girls (TAAG) intervention. The intervention consisted of four synergistic components designed to provide supportive school- and community-linked environments to prevent the decline in physical activity in adolescent girls. Process evaluation results indicate that the intervention components were delivered from intervention staff to teachers with high fidelity (84–97%) to the protocol and with lower fidelity (range: 18–93%) from teachers to students. Physical activity programs for girls, a unique feature of the TAAG intervention, increased from a mean of 10 programs per school to a mean of 16 and 15 in years 1 and 2, respectively, in intervention schools, with no change in control schools. These findings suggest that a multicomponent school- and community-based physical activity intervention can be delivered with fidelity and result in a middle school environment that supports physical activity for girls

    Validation of 3 Food Outlet Databases: Completeness and Geospatial Accuracy in Rural and Urban Food Environments

    Get PDF
    Despite interest in the built food environment, little is known about the validity of commonly used secondary data. The authors conducted a comprehensive field census identifying the locations of all food outlets using a handheld global positioning system in 8 counties in South Carolina (2008–2009). Secondary data were obtained from 2 commercial companies, Dun & Bradstreet, Inc. (D&B) (Short Hills, New Jersey) and InfoUSA, Inc. (Omaha, Nebraska), and the South Carolina Department of Health and Environmental Control (DHEC). Sensitivity, positive predictive value, and geospatial accuracy were compared. The field census identified 2,208 food outlets, significantly more than the DHEC (n = 1,694), InfoUSA (n = 1,657), or D&B (n = 1,573). Sensitivities were moderate for DHEC (68%) and InfoUSA (65%) and fair for D&B (55%). Combining InfoUSA and D&B data would have increased sensitivity to 78%. Positive predictive values were very good for DHEC (89%) and InfoUSA (86%) and good for D&B (78%). Geospatial accuracy varied, depending on the scale: More than 80% of outlets were geocoded to the correct US Census tract, but only 29%–39% were correctly allocated within 100 m. This study suggests that the validity of common data sources used to characterize the food environment is limited. The marked undercount of food outlets and the geospatial inaccuracies observed have the potential to introduce bias into studies evaluating the impact of the built food environment

    The Glial Regenerative Response to Central Nervous System Injury Is Enabled by Pros-Notch and Pros-NFκB Feedback

    Get PDF
    Organisms are structurally robust, as cells accommodate changes preserving structural integrity and function. The molecular mechanisms underlying structural robustness and plasticity are poorly understood, but can be investigated by probing how cells respond to injury. Injury to the CNS induces proliferation of enwrapping glia, leading to axonal re-enwrapment and partial functional recovery. This glial regenerative response is found across species, and may reflect a common underlying genetic mechanism. Here, we show that injury to the Drosophila larval CNS induces glial proliferation, and we uncover a gene network controlling this response. It consists of the mutual maintenance between the cell cycle inhibitor Prospero (Pros) and the cell cycle activators Notch and NFκB. Together they maintain glia in the brink of dividing, they enable glial proliferation following injury, and subsequently they exert negative feedback on cell division restoring cell cycle arrest. Pros also promotes glial differentiation, resolving vacuolization, enabling debris clearance and axonal enwrapment. Disruption of this gene network prevents repair and induces tumourigenesis. Using wound area measurements across genotypes and time-lapse recordings we show that when glial proliferation and glial differentiation are abolished, both the size of the glial wound and neuropile vacuolization increase. When glial proliferation and differentiation are enabled, glial wound size decreases and injury-induced apoptosis and vacuolization are prevented. The uncovered gene network promotes regeneration of the glial lesion and neuropile repair. In the unharmed animal, it is most likely a homeostatic mechanism for structural robustness. This gene network may be of relevance to mammalian glia to promote repair upon CNS injury or disease
    corecore