627 research outputs found

    Interferometric detection of a single vortex in a dilute Bose-Einstein condensate

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    Using two radio frequency pulses separated in time we perform an amplitude division interference experiment on a rubidium Bose-Einstein condensate. The presence of a quantized vortex, which is nucleated by stirring the condensate with a laser beam, is revealed by a dislocation in the fringe pattern.Comment: 4 pages, 4 figure

    Testing quantum correlations in a confined atomic cloud by scattering fast atoms

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    We suggest measuring one-particle density matrix of a trapped ultracold atomic cloud by scattering fast atoms in a pure momentum state off the cloud. The lowest-order probability of the inelastic process, resulting in a pair of outcoming fast atoms for each incoming one, turns out to be given by a Fourier transform of the density matrix. Accordingly, important information about quantum correlations can be deduced directly from the differential scattering cross-section. A possible design of the atomic detector is also discussed.Comment: 5 RevTex pages, no figures, submitted to PR

    Quantifying the impact of variability in railway bridge asset management

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    Bridge asset management is often a challenging and complicated task due to the diversity, multitude and variation of bridge configurations. Much research has been carried out in the field of asset management which has resulted in a wealth of models to help with the decision making process. However, often these models oversimplify the process, resulting in a decision making tool that trivialises the complexity of the decisions. The purpose of this study was to ascertain what the main sources of variability are in the process and then quantify the impact of them in terms of the Whole Life-Cycle Cost (WLCC). The study focuses on human-induced variability to ensure the results are directly influenceable by bridge portfolio managers. The sources of variability identified include misdiagnoses of defects as well as imperfect repairs and variability in costs, all of which are aspects that bridge portfolio managers are exposed to. The sources of variability are quantified and then incorporated into an existing railway bridge WLCC model, established in a previous study, which uses a flexible Petri-Net (PN) approach which is able to incorporate the complex logic and probabilistic aspects. The model itself is able to replicate some of the more complicated decisions which have to be made in bridge asset management, especially those which influence the decisions around rehabilitation. The resulting model, enhanced with the probabilistic variability, is able to reveal the impact of variability on the asset condition, WLCC and even understand where operational complexities are occurring within the system. Incorporating human-induced variability into any model will inevitably increase the financial and operational burden predicted by the model, however, recognising and modelling these aspects is a crucial step in providing bridge portfolio managers a more robust and accurate decision making tool which can more accurately replicate the real world system

    ff-minimal surface and manifold with positive mm-Bakry-\'{E}mery Ricci curvature

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    In this paper, we first prove a compactness theorem for the space of closed embedded ff-minimal surfaces of fixed topology in a closed three-manifold with positive Bakry-\'{E}mery Ricci curvature. Then we give a Lichnerowicz type lower bound of the first eigenvalue of the ff-Laplacian on compact manifold with positive mm-Bakry-\'{E}mery Ricci curvature, and prove that the lower bound is achieved only if the manifold is isometric to the nn-shpere, or the nn-dimensional hemisphere. Finally, for compact manifold with positive mm-Bakry-\'{E}mery Ricci curvature and ff-mean convex boundary, we prove an upper bound for the distance function to the boundary, and the upper bound is achieved if only if the manifold is isometric to an Euclidean ball.Comment: 15 page

    Application of Pulsed Field Gel Electrophoresis to Determine Îł-ray-induced Double-strand Breaks in Yeast Chromosomal Molecules

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    The frequency of DNA double-strand breaks (dsb) was determined in yeast cells exposed to Îł-rays under anoxic conditions. Genomic DNA of treated cells was separated by pulsed field gel electrophoresis, and two different approaches for the evaluation of the gels were employed: (1) The DNA mass distribution profile obtained by electrophoresis was compared to computed profiles, and the number of DSB per unit length was then derived in terms of a fitting procedure; (2) hybridization of selected chromosomes was performed, and a comparison of the hybridization signals in treated and untreated samples was then used to derive the frequency of dsb

    National predictors of influenza vaccine uptake in pregnancy: the FluMum prospective cohort study, Australia, 2012–2015

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    Objective: Ascertain predictors of inactivated influenza vaccine (IIV) uptake in pregnancy in mother–infant pairs from six Australian sites over four consecutive influenza seasons (2012–2015). Methods: Prospective observational cohort study calculating proportions of unvaccinated and vaccinated pregnancies. Multivariable logistic regression calculating adjusted odds ratios (aOR) and 95% confidence intervals (95%CI) to determine demographic, pregnancy and birth characteristics as predictors of IIV uptake in pregnancy. Results: Uptake of IIV was 36% (n=3,651/9,878) with only 3–4% during the first trimester. Validation of IIV receipt was obtained for 77% of vaccinated participants. Predictors of IIV uptake in pregnancy were: healthcare provider recommendation to have IIV during pregnancy (aOR 7.04 [95%CI 5.83-8.50]): GP (aOR 4.12 [95%CI 3.43-4.98]), obstetrician (aOR 4.41 [95%CI 3.45-5.64]), midwife (aOR 1.88 [95%CI 1.51-2.36]); previous IIV within 12 months of their current pregnancy (aOR 2.87 [95%CI 2.36-3.50]); and pertussis vaccination during the current pregnancy (aOR 4.88 [95%CI 4.08-5.83]). Conclusions and implications for public health: Healthcare provider discussions with pregnant women about the risks associated with influenza infection during pregnancy and early infancy and evidence about the safety and effectiveness of IIV are required. Recommending and offering IIV in pregnancy needs to be included in these discussions to improve uptake.Lisa McHugh, Kerry-Ann F. O’Grady, Terry Nolan, Peter C. Richmond, Nicholas Wood, Helen S. Marshall, Stephen B. Lambert, Mark D. Chatfield, Kirsten P. Perrett, Paula Binks, Michael J. Binks, Ross M. Andrew

    Search for a W' boson decaying to a bottom quark and a top quark in pp collisions at sqrt(s) = 7 TeV

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    Results are presented from a search for a W' boson using a dataset corresponding to 5.0 inverse femtobarns of integrated luminosity collected during 2011 by the CMS experiment at the LHC in pp collisions at sqrt(s)=7 TeV. The W' boson is modeled as a heavy W boson, but different scenarios for the couplings to fermions are considered, involving both left-handed and right-handed chiral projections of the fermions, as well as an arbitrary mixture of the two. The search is performed in the decay channel W' to t b, leading to a final state signature with a single lepton (e, mu), missing transverse energy, and jets, at least one of which is tagged as a b-jet. A W' boson that couples to fermions with the same coupling constant as the W, but to the right-handed rather than left-handed chiral projections, is excluded for masses below 1.85 TeV at the 95% confidence level. For the first time using LHC data, constraints on the W' gauge coupling for a set of left- and right-handed coupling combinations have been placed. These results represent a significant improvement over previously published limits.Comment: Submitted to Physics Letters B. Replaced with version publishe

    Search for the standard model Higgs boson decaying into two photons in pp collisions at sqrt(s)=7 TeV

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    A search for a Higgs boson decaying into two photons is described. The analysis is performed using a dataset recorded by the CMS experiment at the LHC from pp collisions at a centre-of-mass energy of 7 TeV, which corresponds to an integrated luminosity of 4.8 inverse femtobarns. Limits are set on the cross section of the standard model Higgs boson decaying to two photons. The expected exclusion limit at 95% confidence level is between 1.4 and 2.4 times the standard model cross section in the mass range between 110 and 150 GeV. The analysis of the data excludes, at 95% confidence level, the standard model Higgs boson decaying into two photons in the mass range 128 to 132 GeV. The largest excess of events above the expected standard model background is observed for a Higgs boson mass hypothesis of 124 GeV with a local significance of 3.1 sigma. The global significance of observing an excess with a local significance greater than 3.1 sigma anywhere in the search range 110-150 GeV is estimated to be 1.8 sigma. More data are required to ascertain the origin of this excess.Comment: Submitted to Physics Letters

    Measurement of the Lambda(b) cross section and the anti-Lambda(b) to Lambda(b) ratio with Lambda(b) to J/Psi Lambda decays in pp collisions at sqrt(s) = 7 TeV

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    The Lambda(b) differential production cross section and the cross section ratio anti-Lambda(b)/Lambda(b) are measured as functions of transverse momentum pt(Lambda(b)) and rapidity abs(y(Lambda(b))) in pp collisions at sqrt(s) = 7 TeV using data collected by the CMS experiment at the LHC. The measurements are based on Lambda(b) decays reconstructed in the exclusive final state J/Psi Lambda, with the subsequent decays J/Psi to an opposite-sign muon pair and Lambda to proton pion, using a data sample corresponding to an integrated luminosity of 1.9 inverse femtobarns. The product of the cross section times the branching ratio for Lambda(b) to J/Psi Lambda versus pt(Lambda(b)) falls faster than that of b mesons. The measured value of the cross section times the branching ratio for pt(Lambda(b)) > 10 GeV and abs(y(Lambda(b))) < 2.0 is 1.06 +/- 0.06 +/- 0.12 nb, and the integrated cross section ratio for anti-Lambda(b)/Lambda(b) is 1.02 +/- 0.07 +/- 0.09, where the uncertainties are statistical and systematic, respectively.Comment: Submitted to Physics Letters
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