4,895 research outputs found

    Psychiatric disorders and risk of subsequent dementia: Systematic review and meta-analysis of longitudinal studies

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    OBJECTIVES: Although psychiatric disorders have been found to be associated with increased risk of dementia, previous findings are mixed, and the nature of these relationships remains poorly understood. We examined longitudinal associations between depression, anxiety, post-traumatic stress disorders (PTSD), bipolar disorder (BPD), psychotic disorders and subsequent dementia. METHODS: We searched three databases for longitudinal, population-based studies investigating associations between psychiatric disorders and dementia (PROSPERO registration: CRD42020209638). We conducted narrative synthesis, and random-effects meta-analyses to obtain pooled estimates. We used meta-regression and stratified analyses to examine variation by sex, age-at-onset and follow-up time. RESULTS: Fifty-seven citations met eligibility criteria. Most studies focussed on depression (n = 33), which was associated with subsequent all-cause dementia (pooled relative risk [RR]: 1.96, 95% confidence interval [CI]: 1.59-2.43; I2  = 96.5%), Alzheimer's Disease (pooled RR: 1.9, 95% CI: 1.52-2.38; I2  = 85.5%), and Vascular Dementia (pooled RR: 2.71, 95% CI: 2.48-2.97; I2  = 0). Associations were stronger in studies with shorter follow-up periods and for severe and late-onset depression. Findings regarding anxiety were mixed, and we did not find evidence of an overall association (pooled RR: 1.18, 95% CI: 0.96-1.45; I2  = 52.2%, n = 5). Despite sparse evidence, psychotic disorders (pooled RR: 2.19, 95% CI: 1.44-3.31; I2  = 99%), PTSD and BPD were associated with subsequent dementia. CONCLUSIONS: People with psychiatric disorders represent high-risk groups for dementia, highlighting the importance of ongoing symptom monitoring in these groups. Findings regarding temporality and age-at-onset indicate that depression symptoms could reflect prodromal dementia for some individuals. Further longitudinal research is required to determine whether psychiatric disorders represent causal risk factors or early markers of dementia neuropathology

    Fully Polynomial Time Approximation Schemes for Stochastic Dynamic Programs

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    We present a framework for obtaining fully polynomial time approximation schemes (FPTASs) for stochastic univariate dynamic programs with either convex or monotone single-period cost functions. This framework is developed through the establishment of two sets of computational rules, namely, the calculus of K-approximation functions and the calculus of K-approximation sets. Using our framework, we provide the first FPTASs for several NP-hard problems in various fields of research such as knapsack models, logistics, operations management, economics, and mathematical finance. Extensions of our framework via the use of the newly established computational rules are also discussed

    On the eigenvalues of Cayley graphs on the symmetric group generated by a complete multipartite set of transpositions

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    Given a finite simple graph \cG with nn vertices, we can construct the Cayley graph on the symmetric group SnS_n generated by the edges of \cG, interpreted as transpositions. We show that, if \cG is complete multipartite, the eigenvalues of the Laplacian of \Cay(\cG) have a simple expression in terms of the irreducible characters of transpositions, and of the Littlewood-Richardson coefficients. As a consequence we can prove that the Laplacians of \cG and of \Cay(\cG) have the same first nontrivial eigenvalue. This is equivalent to saying that Aldous's conjecture, asserting that the random walk and the interchange process have the same spectral gap, holds for complete multipartite graphs.Comment: 29 pages. Includes modification which appear on the published version in J. Algebraic Combi

    Retrospective Analysis to Describe Associations Between Tumor Necrosis Factor Alpha Inhibitors and COPD-Related Hospitalizations

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    Background: Limited information exists on the impact of tumor necrosis factor inhibition on COPD exacerbations. This retrospective study characterized this impact among COPD patients with underlying autoimmune conditions, exposed to tumor necrosis factor inhibitors (TNFi) and/or non-biologic disease-modifying antirheumatic drugs (DMARDs).Patients and methods: Adult COPD patients with ≥1 diagnosis for rheumatoid arthritis (RA), psoriasis (PsO), psoriatic arthritis (PsA), or ankylosing spondylitis (AS) before or within 6 months following the index COPD diagnosis were identified from the Truven Health MarketScan® databases. Patients were required to have a second claim for RA, PsO, PsA, AS, or DMARD use (biologic or non-biologic) prior to or up to 6 months following the index date. Incidence of COPD-related hospitalizations and emergency room (ER) visits was evaluated in relation to treatment with TNFi and/or DMARDs and other potential risk factors.Results: The study cohort included 40,687 patients (untreated, 37.7%; non-biologic DMARD, 35.4%; TNFi + non-biologic DMARD, 18%; TNFi, 8.8%). The proportion of patients with a COPD-related hospitalization and the incidence of COPD-related hospitalization (per 100 person-years) were lowest in the TNFi cohort (8.6%; 3.54, 95% confidence interval [CI]: 3.16–3.95) and the TNFi + non-biologic DMARD cohort (8.4%; 2.85, 95% CI: 2.63–3.08). In multivariate models, treatment with TNFi + non-biologic DMARD reduced the risk of COPD-related hospitalization or ER visits by 32% relative to non-biologic DMARDs (hazard ratio: 0.68; 95% CI: 0.61–0.75).Conclusion: In real-world settings, TNFi monotherapy confers similar risk for COPD-related hospitalization or ER visits as a non-biologic DMARD. Decreased risk was found among those treated with both TNFi and a non-biologic DMARD

    Space-Time Clustering and Correlations of Major Earthquakes

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    Earthquake occurrence in nature is thought to result from correlated elastic stresses, leading to clustering in space and time. We show that occurrence of major earthquakes in California correlates with time intervals when fluctuations in small earthquakes are suppressed relative to the long term average. We estimate a probability of less than 1% that this coincidence is due to random clustering.Comment: 5 pages, 3 figures. Submitted to PR

    Constraining the quantum gravity polymer scale using LIGO data

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    We present the first empirical constraints on the polymer scale describing polymer quantized GWs propagating on a classical background. These constraints are determined from the polymer-induced deviation from the classically predicted propagation speed of GWs. We leverage posterior information on the propagation speed of GWs from two previously reported sources: 1) inter-detector arrival time delays for signals from the LIGO-Virgo Collaboration's first gravitational-wave transient catalog, GWTC1, and 2) from arrival time delays between GW signal GW170817 and its associated gamma-ray burst GRB170817A. For pure-GW constraints, we find relatively uninformative combined constraints of ν=0.96+0.15−0.21×10−53 kg1/2\nu = 0.96\substack{+0.15 \\ -0.21} \times 10^{-53} \, \rm{kg}^{1/2} and μ=0.94+0.75−0.20×10−48 kg1/2⋅s\mu = 0.94\substack{+0.75 \\ -0.20} \times 10^{-48} \, \rm{kg}^{1/2} \cdot s at the 90%90\% credible level for the two polymer quantization schemes, where ν\nu and μ\mu refer to polymer parameters associated to the polymer quantization schemes of propagating gravitational degrees of freedom. For constraints from GW170817/GRB170817A, we report much more stringent constraints of νlow=2.66+0.60−0.10×10−56\nu_{\mathrm{low}} =2.66\substack{+0.60 \\ -0.10}\times 10^{-56}, νhigh=2.66+0.45−0.10×10−56\nu_{\mathrm{high}} = 2.66\substack{+0.45 \\ -0.10}\times 10^{-56} and μlow=2.84+0.64−0.11×10−52\mu_{\mathrm{low}} = 2.84\substack{+0.64 \\ -0.11}\times 10^{-52}, μhigh=2.76+0.46−0.11×10−52\mu_{\mathrm{high}} = 2.76\substack{+0.46 \\ -0.11}\times 10^{-52} for both representations of polymer quantization and two choices of spin prior indicated by the subscript. Additionally, we explore the effect of varying the lag between emission of the GW and EM signals in the multimessenger case.Comment: Invited contribution to "Focus issue on Quantum Gravity Phenomenology in the Multi-Messenger Era: Challenges and Perspectives" to appear in Classical and Quantum Gravity, 18 pages, 6 figures, Part of the COST Action CA18108: Quantum gravity phenomenology in the multi-messenger approac

    Lidar technology measurements and technology: Report of panel

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    Lidar is ready to make an important contribution to tropospheric chemistry research with a variety of spaceborne measurements that complement the measurements from passive instruments. Lidar can now be considered for near-term and far-term space missions dealing with a number of scientifically important issues in tropospheric chemistry. The evolution in the lidar missions from space are addressed and details of these missions are given. The laser availability for space missions based upon the technical data is assessed

    Evidence of Dynamical Spin Shielding in Ce from Spin-Resolved Photoelectron Spectroscopy

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    Using Fano effect measurements upon polycrystalline Ce, we have observed a phase reversal between the spectral structure at the Fermi edge and the other 4f derived feature near a binding energy of 2 eV. The Fano effect is the observation of spin polarized photoelectron emission from nonmagnetic materials, under chirally selective excitation, such as circularly polarized photons. The observation of phase reversal between the two peaks is a direct experimental proof of Kondo shielding in Ce, confirming the predictions of Gunnarsson and Shoenhammer, albeit with a small modification
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