335 research outputs found

    Description of superdeformed nuclei in the interacting boson model

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    The interacting boson model is extended to describe the spectroscopy of superdeformed bands. Microscopic structure of the model in the second minimum is discussed and superdeformed bosons are introduced as the new building blocks. Solutions of a quadrupole Hamiltonian are implemented through the 1/N1/N expansion method. Effects of the quadrupole parameters on dynamic moment of inertia and electric quadrupole transition rates are discussed and the results are used in a description of superdeformed bands in the Hg-Pb and Gd-Dy regions.Comment: 18 pages revtex, 9 figures available upon reques

    Solution of the Kwiecinski evolution equations for unintegrated parton distributions using the Mellin transform

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    The Kwiecinski equations for the QCD evolution of the unintegrated parton distributions in the transverse-coordinate space (b) are analyzed with the help of the Mellin-transform method. The equations are solved numerically in the general case, as well as in a small-b expansion which converges fast for b Lambda_QCD sufficiently small. We also discuss the asymptotic limit of large bQ and show that the distributions generated by the evolution decrease with b according to a power law. Numerical results are presented for the pion distributions with a simple valence-like initial condition at the low scale, following from chiral large-N_c quark models. We use two models: the Spectral Quark Model and the Nambu--Jona-Lasinio model. Formal aspects of the equations, such as the analytic form of the b-dependent anomalous dimensions, their analytic structure, as well as the limits of unintegrated parton densities at x -> 0, x -> 1, and at large b, are discussed in detail. The effect of spreading of the transverse momentum with the increasing scale is confirmed, with growing asymptotically as Q^2 alpha(Q^2). Approximate formulas for for each parton species is given, which may be used in practical applications.Comment: 18 pages, 6 figures, RevTe

    Prevalence and 1-year incidence of frailty among women with and without HIV in the Women's Interagency HIV Study

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    A previous cross-sectional analysis of 2028 women in the Women’s Interagency HIV Study (WIHS), who were on average 39 years old, found a frailty prevalence of 17% and 10% in women with or at risk for HIV, respectively [1]. To our knowledge, the only two longitudinal studies of frailty among people with HIV were conducted in the Multicenter AIDS Cohort Study (MACS), which includes only men [2,3]. Data on the distribution of frailty components are limited, and have not been reported for HIV-seropositive people in the United State

    The impact of musculoskeletal ill health on quality of life and function after critical care : a multicentre prospective cohort study

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    Physical disability is a common component of post-intensive care syndrome, but the importance of musculoskeletal health in this population is currently unknown. We aimed to determine the musculoskeletal health state of intensive care unit survivors and assess its relationship with health-related quality of life; employment; and psychological and physical function. We conducted a multicentre prospective cohort study of adults admitted to intensive care for > 48 h without musculoskeletal trauma or neurological insult. Patients were followed up 6 months after admission where musculoskeletal health state was measured using the validated Musculoskeletal Health Questionnaire score. Of the 254 participants, 150 (59%) had a musculoskeletal problem and only 60 (24%) had received physiotherapy after discharge. Functional Comorbidity Index, Clinical Frailty Scale, duration of intensive care unit stay and prone positioning were all independently associated with worse musculoskeletal health. Musculoskeletal health state moderately correlated with quality of life, rs = 0.499 (95%CI 0.392–0.589); anxiety, rs = -0.433 (95%CI -0.538 to -0.315); and depression, rs = -0.537 (95%CI -0.631 to -0.434) (all p < 0.001). Patients with a musculoskeletal problem were less physically active than those without a problem (median (IQR [range]) number of 30 min physical activity sessions per week 1 (0–3.25 [0–7]) vs. 4 (1–7 [0–7]), p < 0.001, respectively). This study found that musculoskeletal health problems were common after intensive care unit stay. However, we observed that < 25% of patients received physical rehabilitation after discharge home. Our work has identified potential high-risk groups to target in future interventional studies

    Propagating two-dimensional magnetic droplets

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    Propagating, solitary magnetic wave solutions of the Landau-Lifshitz equation with uniaxial, easy-axis anisotropy in thin (two-dimensional) magnetic films are investigated. These localized, nontopological wave structures, parametrized by their precessional frequency and propagation speed, extend the stationary, coherently precessing "magnon droplet" to the moving frame, a non-trivial generalization due to the lack of Galilean invariance. Propagating droplets move on a spin wave background with a nonlinear droplet dispersion relation that yields a limited range of allowable droplet speeds and frequencies. An iterative numerical technique is used to compute the propagating droplet's structure and properties. The results agree with previous asymptotic calculations in the weakly nonlinear regime. Furthermore, an analytical criterion for the droplet's orbital stability is confirmed. Time-dependent numerical simulations further verify the propagating droplet's robustness to perturbation when its frequency and speed lie within the allowable range.Comment: 16 pages, 11 figure

    Decomposition of the QCD String into Dipoles and Unintegrated Gluon Distributions

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    We present the perturbative and non-perturbative QCD structure of the dipole-dipole scattering amplitude in momentum space. The perturbative contribution is described by two-gluon exchange and the non-perturbative contribution by the stochastic vacuum model which leads to confinement of the quark and antiquark in the dipole via a string of color fields. This QCD string gives important non-perturbative contributions to high-energy reactions. A new structure different from the perturbative dipole factors is found in the string-string scattering amplitude. The string can be represented as an integral over stringless dipoles with a given dipole number density. This decomposition of the QCD string into dipoles allows us to calculate the unintegrated gluon distribution of hadrons and photons from the dipole-hadron and dipole-photon cross section via kT-factorization.Comment: 43 pages, 14 figure

    Peripheral artery disease and physical function in women with and without HIV

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    Objectives: Peripheral artery disease (PAD) is associated with decreased physical function and increased mortality in the general population. We previously found that PAD is common in middle-aged women with and without HIV infection, but its association with functional decline is unclear. We examine the contribution of PAD to functional decline in the Women’s Interagency HIV Study, controlling for traditional cardiovascular risk factors and HIV-related factors. Methods: Analysis included 1839 participants (72% with HIV) with measured ankle – brachial index (ABI) and 4 m gait speed. ABI values categorized PAD severity. Linear models with repeated measures estimated the association of PAD severity with log-transformed gait speed after controlling for demographic, behavioral, and metabolic risk factors, and HIV/hepatitis C virus status. Results: Median age was 50 years and more than 70% were Black. Compared with normal ABI, there was a dose – response relationship between increasing PAD severity and slower gait speed in univariable analyses: 6% slower gait speed for low-normal ABI [95% confidence interval (CI): 4 – 9%], 10% for borderline PAD (95% CI: 6 – 13%), 14% for mild PAD (95% CI: 9 – 18%), and 16% for moderate – severe PAD (95% CI: 5 – 25%). PAD severity remained associated with slower gait speed in multivariable analyses. HIV/hepatitis C virus co-infection was independently associated with 9% (95% CI: 4 – 14%) slower gait speed compared with those with neither infection. Among women with HIV, neither CD4þ cell count nor HIV-RNA level was associated with gait speed. Conclusion: In middle-aged women with and without HIV infection, greater PAD severity is associated with progressively slower gait speed. Early detection of subclinical PAD may decrease the risk of lower extremity functional impairment and its long-term health consequences

    Association of Adherence to a Healthy Diet with Cognitive Decline in European and American Older Adults

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    Aim: To examine the association between a healthy diet, assessed by the Healthy Diet Indicator (HDI), and cognitive decline in older adults. Methods: Data from 21,837 participants aged ≥ 55 years from 3 cohorts (Survey in Europe on Nutrition and the Elderly, a Concerted Action[SENECA], Rotterdam Study [RS], Nurses’ Health Study [NHS]) were analyzed. HDI scores were based on intakes of saturated fatty acids, polyunsaturated fatty acids, mono- and disaccharides, protein, cholesterol, fruits and vegetables, and fiber. The Telephone Interview for Cognitive Status in NHS and Mini-Mental State Examination in RS and SENECA were used to assess cognitive function from multiple repeated measures. Using multivariable-adjusted, mixed linear regression, mean differences in annual rates of cognitive decline by HDI quintiles were estimated. Results: Multivariable-adjusted differences in rates in the highest versus the lowest HDI quintile were 0.01 (95% CI –0.01, 0.02) in NHS, 0.00 (95% CI –0.02, 0.01) in RS, and 0.00 (95% CI –0.05, 0.05) in SENECA with a pooled estimate of 0.00 (95% CI –0.01, 0.01), I 2 = 0%. Conclusions: A higher HDI score was not related to reduced rates of cognitive decline in European and American older adults

    Detector Description and Performance for the First Coincidence Observations between LIGO and GEO

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    For 17 days in August and September 2002, the LIGO and GEO interferometer gravitational wave detectors were operated in coincidence to produce their first data for scientific analysis. Although the detectors were still far from their design sensitivity levels, the data can be used to place better upper limits on the flux of gravitational waves incident on the earth than previous direct measurements. This paper describes the instruments and the data in some detail, as a companion to analysis papers based on the first data.Comment: 41 pages, 9 figures 17 Sept 03: author list amended, minor editorial change
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