98 research outputs found

    Search for Tensor, Vector, and Scalar Polarizations in the Stochastic Gravitational-Wave Background

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    The detection of gravitational waves with Advanced LIGO and Advanced Virgo has enabled novel tests of general relativity, including direct study of the polarization of gravitational waves. While general relativity allows for only two tensor gravitational-wave polarizations, general metric theories can additionally predict two vector and two scalar polarizations. The polarization of gravitational waves is encoded in the spectral shape of the stochastic gravitational-wave background, formed by the superposition of cosmological and individually unresolved astrophysical sources. Using data recorded by Advanced LIGO during its first observing run, we search for a stochastic background of generically polarized gravitational waves. We find no evidence for a background of any polarization, and place the first direct bounds on the contributions of vector and scalar polarizations to the stochastic background. Under log-uniform priors for the energy in each polarization, we limit the energy densities of tensor, vector, and scalar modes at 95% credibility to Ω0T<5.58×10-8, Ω0V<6.35×10-8, and Ω0S<1.08×10-7 at a reference frequency f0=25 Hz. © 2018 American Physical Society

    Biotechnological approaches for plant viruses resistance: from general to the modern RNA silencing pathway

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    Prevalence of Age-Related Macular Degeneration in Europe: The Past and the Future

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    Purpose Age-related macular degeneration (AMD) is a frequent, complex disorder in elderly of European ancestry. Risk profiles and treatment options have changed considerably over the years, which may have affected disease prevalence and outcome. We determined the prevalence of early and late AMD in Europe from 1990 to 2013 using the European Eye Epidemiology (E3) consortium, and made projections for the future. Design Meta-analysis of prevalence data. Participants A total of 42 080 individuals 40 years of age and older participating in 14 population-based cohorts from 10 countries in Europe. Methods AMD was diagnosed based on fundus photographs using the Rotterdam Classification. Prevalence of early and late AMD was calculated using random-effects meta-analysis stratified for age, birth cohort, gender, geographic region, and time period of the study. Best-corrected visual acuity (BCVA) was compared between late AMD subtypes; geographic atrophy (GA) and choroidal neovascularization (CNV). Main Outcome Measures Prevalence of early and late AMD, BCVA, and number of AMD cases. Results Prevalence of early AMD increased from 3.5% (95% confidence interval [CI] 2.1%–5.0%) in those aged 55–59 years to 17.6% (95%

    On the progenitor of binary neutron star merger GW170817

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    On 2017 August 17 the merger of two compact objects with masses consistent with two neutron stars was discovered through gravitational-wave (GW170817), gamma-ray (GRB 170817A), and optical (SSS17a/AT 2017gfo) observations. The optical source was associated with the early-type galaxy NGC 4993 at a distance of just ∌40 Mpc, consistent with the gravitational-wave measurement, and the merger was localized to be at a projected distance of ∌2 kpc away from the galaxy's center. We use this minimal set of facts and the mass posteriors of the two neutron stars to derive the first constraints on the progenitor of GW170817 at the time of the second supernova (SN). We generate simulated progenitor populations and follow the three-dimensional kinematic evolution from binary neutron star (BNS) birth to the merger time, accounting for pre-SN galactic motion, for considerably different input distributions of the progenitor mass, pre-SN semimajor axis, and SN-kick velocity. Though not considerably tight, we find these constraints to be comparable to those for Galactic BNS progenitors. The derived constraints are very strongly influenced by the requirement of keeping the binary bound after the second SN and having the merger occur relatively close to the center of the galaxy. These constraints are insensitive to the galaxy's star formation history, provided the stellar populations are older than 1 Gyr

    Relationship of patient characteristics and inpatient rehabilitation services to 5-year outcomes following spinal cord injury: A follow up of the SCIRehab project

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    Objective: To examine associations of patient characteristics and treatment quantity delivered during inpatient spinal cord injury (SCI) rehabilitation with outcomes at 5 years post-injury and compare them to the associations found at 1 year post-injury. Design: Observational study using Practice-Based Evidence research methodology in which clinicians documented treatment details. Regression modeling was used to predict outcomes. Setting: Five inpatient SCI rehabilitation centers in the US. Participants: Participants were 792 SCIRehab participants who were >12 years of age, gave informed consent, and completed both a 1-year and 5-year post-injury interview. Outcome measures: Outcome data were derived from Spinal Cord Injury Model Systems (SCIMS) follow-up interviews at 5 years post-injury and, similar to the 1-year SCIMS outcomes, included measures of physical independence, societal participation, life satisfaction, and depressive symptoms, as well as place of residence, school/work attendance, rehospitalization, and presence of pressure ulcers. Results: Consistent with 1-year findings, patient characteristics continue to be strong predictors of outcomes 5-years post-injury, although several variables add to the prediction of some of the outcomes. More time in physical therapy and therapeutic recreation were positive predictors of 1-year outcomes, which held less true at 5 years. Greater time spent with psychology and social work/case management predicted greater depressive symptomatology 5-years post-injury. Greater clinician experience was a predictor at both 1- and 5 -years, although the related positive outcomes varied across years. Conclusion: Various outcomes 5-years post-injury were primarily explained by pre-and post-injury characteristics, with little additional variance offered by the quantity of treatment received during inpatient rehabilitation
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