811 research outputs found

    Physical health and the onset and persistence of depression in older adults: an eight-wave prospective community based study.

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    Background. Poor physical health has long been recognized to be one of the most important risk factors for depression in older adults. Since many aspects of physical health can be targeted for improvement in primary care, it is important to know whether physical health problems predict the onset and/or the persistence of depression. Methods. The study is based on a sample which at the outset consisted of 327 depressed and 325 non-depressed older adults (55-85) drawn from a larger random community-based sample in the Netherlands. Depression was measured using the Center for Epidemiologic Studies Depression scale (CES-D) at eight successive waves. Results. From all incident episodes, the majority (57%) was short-lived. These short episodes could generally not be predicted by physical health problems. The remaining incident episodes (43%) were not short-lived and could be predicted by poor physical health. Chronicity (34%) was also predicted by physical health problems. Conclusions. The study design with its frequent measurements recognized more incident cases than previous studies; these cases however did have a better prognosis than is often assumed. The prognosis of prevalent cases was rather poor. Physical health problems were demonstrated to be a predictor of both the onset and the persistence of depression. This may well have implications for prevention and intervention

    Asymptotic tunneling conductance in Luttinger liquids

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    Conductance through weak constrictions in Luttinger liquids is shown to vanish with frequency ω\omega as c1ω2+c2ω2/g2c_1 \omega^2 + c_2 \omega^{2/g - 2}, where gg is a dimensionless parameter characterizing the Luttinger liquid phase, and c1c_1 and c2c_2 are nonuniversal constants. The first term arises from the ^^ Coulomb blockade' effect and dominates for g<1/2g < 1/2, whereas the second results from eliminating high-energy modes and dominates for g>1/2g > 1/2.Comment: Latex file + one appended postcript figur

    Resonant Photon-Assisted Tunneling Through a Double Quantum Dot: An Electron Pump From Spatial Rabi Oscillations

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    The time average of the fully nonlinear current through a double quantum dot, subject to an arbitrary combination of ac and dc voltages, is calculated exactly using the Keldysh nonequilibrium Green function technique. When driven on resonance, the system functions as an efficient electron pump due to Rabi oscillation between the dots. The pumping current is maximum when the coupling to the leads equals the Rabi frequency.Comment: 6 pages, REVTEX 3.0, 3 postscript figure

    Coordinated analysis of age, sex, and education effects on change in MMSE scores

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    Objectives. We describe and compare the expected performance trajectories of older adults on the Mini-Mental Status Examination (MMSE) across six independent studies from four countries in the context of a collaborative network of longitudinal studies of aging. A coordinated analysis approach is used to compare patterns of change conditional on sample composition differences related to age, sex, and education. Such coordination accelerates evaluation of particular hypotheses. In particular, we focus on the effect of educational attainment on cognitive decline.Method. Regular and Tobit mixed models were fit to MMSE scores from each study separately. The effects of age, sex, and education were examined based on more than one centering point.Results. Findings were relatively consistent across studies. On average, MMSE scores were lower for older individuals and declined over time. Education predicted MMSE score, but, with two exceptions, was not associated with decline in MMSE over time.Conclusion. A straightforward association between educational attainment and rate of cognitive decline was not supported. Thoughtful consideration is needed when synthesizing evidence across studies, as methodologies adopted and sample characteristics, such as educational attainment, invariably differ. © 2012 The Author

    Kidney Transplantation in Primary Oxalosis: Data From the EDTA Registry

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    This paper reports the results of 98 first kidney transplantations in patients with oxalosis as the primary renal disease as recorded by the EDTA Registry. There were 79 patients who received a cadaveric (CAD) graft and 15 patients with a living related donor (LRD) graft; the type of donor was not recorded for four patients. Initial graft survival appeared to be better after LRD as compared to CAD grafts but at 3 years the poor survival was similar with 23% for LRD and 17% for CAD grafts. CAD graft survival did not differ between children and adults and was not affected by the waiting time on dialysis. A slight improvement was observed in grafts performed in the years 1983-1986 as compared to grafts performed in earlier years. The causes of failure reported were mainly rejection (33%) and recurrence of primary renal disease (31%). In view of the poor results related to recurrence of oxalosis in the graft, the potential ofcombined kidney and liver transplantation is discusse

    Critical properties of two-dimensional Josephson junction arrays with zero-point quantum fluctuations

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    We present results from an extensive analytic and numerical study of a two-dimensional model of a square array of ultrasmall Josephson junctions. We include the ultrasmall self and mutual capacitances of the junctions, for the same parameter ranges as those produced in the experiments. The model Hamiltonian studied includes the Josephson, EJE_J, as well as the charging, ECE_C, energies between superconducting islands. The corresponding quantum partition function is expressed in different calculationally convenient ways within its path-integral representation. The phase diagram is analytically studied using a WKB renormalization group (WKB-RG) plus a self-consistent harmonic approximation (SCHA) analysis, together with non-perturbative quantum Monte Carlo simulations. Most of the results presented here pertain to the superconductor to normal (S-N) region, although some results for the insulating to normal (I-N) region are also included. We find very good agreement between the WKB-RG and QMC results when compared to the experimental data. To fit the data, we only used the experimentally determined capacitances as fitting parameters. The WKB-RG analysis in the S-N region predicts a low temperature instability i.e. a Quantum Induced Transition (QUIT). We carefully simulations and carry out a finite size analysis of TQUITT_{QUIT} as a function of the magnitude of imaginary time axis LτL_\tau. We find that for some relatively large values of α=EC/EJ\alpha=E_C/E_J (1α2.25)1\leq \alpha \leq 2.25), the LτL_\tau\to\infty limit does appear to give a {\it non-zero} TQUITT_{QUIT}, while for α2.5\alpha \ge 2.5, TQUIT=0T_{QUIT}=0. We use the SCHA to analytically understand the LτL_\tau dependence of the QMC results with good agreement between them. Finally, we also carried out a WKB-RG analysis in the I-N region and found no evidence of a low temperature QUIT, up to lowest order in α1{\alpha}^{-1}Comment: 39 pages, 18 postscript figures, to appear in Phys. Rev.
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