4,895 research outputs found
Psychiatric disorders and risk of subsequent dementia: Systematic review and meta-analysis of longitudinal studies
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
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
Given a finite simple graph \cG with vertices, we can construct the
Cayley graph on the symmetric group 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
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
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
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 and at the credible level for the two polymer
quantization schemes, where and 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 , and , 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
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
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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