691 research outputs found
Wide twin binaries are extremely eccentric: evidence of twin binary formation in circumbinary disks
The Gaia mission recently revealed an excess population of equal-mass "twin"
wide binaries, with mass ratio , extending to separations of at
least 1000 AU. The origin of this population is an enigma: twin binaries are
thought to form via correlated accretion in circumbinary disks, but the typical
observed protostellar disks have radii of AU, far smaller than the
separations of the widest twins. Here, we infer the eccentricity distribution
of wide twins from the distribution of their - angles, i.e., the angle
between the components' separation and relative velocity vectors. We find that
wide twins must be on extremely eccentric orbits. For the excess-twin
population at 400-1000 AU, we infer a near-delta function excess of
high-eccentricity system, with eccentricity . These
high eccentricities for wide twins imply pericenter distances of order AU
and suggest that their orbits were scattered via dynamical interactions in
their birth environments, consistent with a scenario in which twins are born in
circumbinary disks and subsequently widened. These results further establish
twin wide binaries as a distinct population and imply that wide twins can be
used as a probe of the dynamical history of stellar populations.Comment: accepted for publication in The Astrophysical Journal Lette
Measuring The Mass-Radius Relation of White Dwarfs Using Wide Binaries
Measuring the mass-radius relation of individual white dwarfs is an
empirically challenging task that has been performed for only a few dozen
stars. We measure the white dwarf mass-radius relation using gravitational
redshifts and radii of 137 white dwarfs in wide binaries with main sequence
companions. We obtain the space velocities to these systems using the main
sequence companion, and subtract these Doppler redshifts from the white dwarfs'
apparent motions, isolating their gravitational redshifts. We use Gaia data to
calculate the surface temperatures and radii of these white dwarfs, thereby
deriving an empirical gravitational redshift-radius relation. This work
demonstrates the utility of low-resolution Galactic surveys to measure the
white dwarf equation of state. Our results are consistent with theoretical
models, and represent the largest sample of individual white dwarf
gravitational redshift measurements to date.Comment: 12 pages, 9 figure
Clinical diagnostic utility of transcranial magnetic stimulation in neurological disorders. Updated report of an IFCN committee
The review provides a comprehensive update (previous report: Chen R, Cros D, Curra A, Di Lazzaro V,
Lefaucheur JP, Magistris MR, et al. The clinical diagnostic utility of transcranial magnetic stimulation:
report of an IFCN committee. Clin Neurophysiol 2008;119(3):504–32) on clinical diagnostic utility of
transcranial magnetic stimulation (TMS) in neurological diseases. Most TMS measures rely on stimulation
of motor cortex and recording of motor evoked potentials. Paired-pulse TMS techniques, incorporating
conventional amplitude-based and threshold tracking, have established clinical utility in neurodegenerative,
movement, episodic (epilepsy, migraines), chronic pain and functional diseases. Cortical hyperexcitability
has emerged as a diagnostic aid in amyotrophic lateral sclerosis. Single-pulse TMS measures are
of utility in stroke, and myelopathy even in the absence of radiological changes. Short-latency afferent
inhibition, related to central cholinergic transmission, is reduced in Alzheimer’s disease. The triple stimulation
technique (TST) may enhance diagnostic utility of conventional TMS measures to detect upper
motor neuron involvement. The recording of motor evoked potentials can be used to perform functional
mapping of the motor cortex or in preoperative assessment of eloquent brain regions before surgical
resection of brain tumors. TMS exhibits utility in assessing lumbosacral/cervical nerve root function,
especially in demyelinating neuropathies, and may be of utility in localizing the site of facial nerve palsies.
TMS measures also have high sensitivity in detecting subclinical corticospinal lesions in multiple
sclerosis. Abnormalities in central motor conduction time or TST correlate with motor impairment and
disability in MS. Cerebellar stimulation may detect lesions in the cerebellum or cerebello-dentatothalamo-
motor cortical pathways. Combining TMS with electroencephalography, provides a novel
method to measure parameters altered in neurological disorders, including cortical excitability, effective
connectivity, and response complexity
Processing and turnover of the Hedgehog protein in the endoplasmic reticulum
Autocatalytic processing of the Hedgehog ligand from its precursor protein relies on protein disulfide isomerase and ER-associated degradation
Maternal mortality and morbidity burden in the Eastern Mediterranean region : findings from the Global Burden of Disease 2015 study
Assessing the burden of maternal mortality is important for tracking progress and identifying public health gaps. This paper provides an overview of the burden of maternal mortality in the Eastern Mediterranean Region (EMR) by underlying cause and age from 1990 to 2015.
We used the results of the Global Burden of Disease 2015 study to explore maternal mortality in the EMR countries.
The maternal mortality ratio in the EMR decreased 16.3% from 283 (241-328) maternal deaths per 100,000 live births in 1990 to 237 (188-293) in 2015. Maternal mortality ratio was strongly correlated with socio-demographic status, where the lowest-income countries contributed the most to the burden of maternal mortality in the region.
Progress in reducing maternal mortality in the EMR has accelerated in the past 15 years, but the burden remains high. Coordinated and rigorous efforts are needed to make sure that adequate and timely services and interventions are available for women at each stage of reproductive life
Alcohol use and burden for 195 countries and territories, 1990-2016 : a systematic analysis for the Global Burden of Disease Study 2016
Background Alcohol use is a leading risk factor for death and disability, but its overall association with health remains complex given the possible protective effects of moderate alcohol consumption on some conditions. With our comprehensive approach to health accounting within the Global Burden of Diseases, Injuries, and Risk Factors Study 2016, we generated improved estimates of alcohol use and alcohol-attributable deaths and disability-adjusted life-years (DALYs) for 195 locations from 1990 to 2016, for both sexes and for 5-year age groups between the ages of 15 years and 95 years and older. Methods Using 694 data sources of individual and population-level alcohol consumption, along with 592 prospective and retrospective studies on the risk of alcohol use, we produced estimates of the prevalence of current drinking, abstention, the distribution of alcohol consumption among current drinkers in standard drinks daily (defined as 10 g of pure ethyl alcohol), and alcohol-attributable deaths and DALYs. We made several methodological improvements compared with previous estimates: first, we adjusted alcohol sales estimates to take into account tourist and unrecorded consumption; second, we did a new meta-analysis of relative risks for 23 health outcomes associated with alcohol use; and third, we developed a new method to quantify the level of alcohol consumption that minimises the overall risk to individual health. Findings Globally, alcohol use was the seventh leading risk factor for both deaths and DALYs in 2016, accounting for 2.2% (95% uncertainty interval [UI] 1.5-3.0) of age-standardised female deaths and 6.8% (5.8-8.0) of age-standardised male deaths. Among the population aged 15-49 years, alcohol use was the leading risk factor globally in 2016, with 3.8% (95% UI 3.2-4-3) of female deaths and 12.2% (10.8-13-6) of male deaths attributable to alcohol use. For the population aged 15-49 years, female attributable DALYs were 2.3% (95% UI 2.0-2.6) and male attributable DALYs were 8.9% (7.8-9.9). The three leading causes of attributable deaths in this age group were tuberculosis (1.4% [95% UI 1. 0-1. 7] of total deaths), road injuries (1.2% [0.7-1.9]), and self-harm (1.1% [0.6-1.5]). For populations aged 50 years and older, cancers accounted for a large proportion of total alcohol-attributable deaths in 2016, constituting 27.1% (95% UI 21.2-33.3) of total alcohol-attributable female deaths and 18.9% (15.3-22.6) of male deaths. The level of alcohol consumption that minimised harm across health outcomes was zero (95% UI 0.0-0.8) standard drinks per week. Interpretation Alcohol use is a leading risk factor for global disease burden and causes substantial health loss. We found that the risk of all-cause mortality, and of cancers specifically, rises with increasing levels of consumption, and the level of consumption that minimises health loss is zero. These results suggest that alcohol control policies might need to be revised worldwide, refocusing on efforts to lower overall population-level consumption.Peer reviewe
New genetic loci link adipose and insulin biology to body fat distribution.
Body fat distribution is a heritable trait and a well-established predictor of adverse metabolic outcomes, independent of overall adiposity. To increase our understanding of the genetic basis of body fat distribution and its molecular links to cardiometabolic traits, here we conduct genome-wide association meta-analyses of traits related to waist and hip circumferences in up to 224,459 individuals. We identify 49 loci (33 new) associated with waist-to-hip ratio adjusted for body mass index (BMI), and an additional 19 loci newly associated with related waist and hip circumference measures (P < 5 × 10(-8)). In total, 20 of the 49 waist-to-hip ratio adjusted for BMI loci show significant sexual dimorphism, 19 of which display a stronger effect in women. The identified loci were enriched for genes expressed in adipose tissue and for putative regulatory elements in adipocytes. Pathway analyses implicated adipogenesis, angiogenesis, transcriptional regulation and insulin resistance as processes affecting fat distribution, providing insight into potential pathophysiological mechanisms
Measuring progress and projecting attainment on the basis of past trends of the health-related Sustainable Development Goals in 188 countries: an analysis from the Global Burden of Disease Study 2016
The UN’s Sustainable Development Goals (SDGs) are grounded in the global ambition of “leaving no one behind”. Understanding today’s gains and gaps for the health-related SDGs is essential for decision makers as they aim to improve the health of populations. As part of the Global Burden of Diseases, Injuries, and Risk Factors Study 2016 (GBD 2016), we measured 37 of the 50 health-related SDG indicators over the period 1990–2016 for 188 countries, and then on the basis of these past trends, we projected indicators to 2030
Global, regional, and national incidence, prevalence, and years lived with disability for 328 diseases and injuries for 195 countries, 1990–2016: a systematic analysis for the Global Burden of Disease Study 2016
As mortality rates decline, life expectancy increases, and populations age, non-fatal outcomes of diseases and injuries are becoming a larger component of the global burden of disease. The Global Burden of Diseases, Injuries, and Risk Factors Study 2016 (GBD 2016) provides a comprehensive assessment of prevalence, incidence, and years lived with disability (YLDs) for 328 causes in 195 countries and territories from 1990 to 2016
Global, regional, and national under-5 mortality, adult mortality, age-specific mortality, and life expectancy, 1970–2016: a systematic analysis for the Global Burden of Disease Study 2016
BACKGROUND: Detailed assessments of mortality patterns, particularly age-specific mortality, represent a crucial input that enables health systems to target interventions to specific populations. Understanding how all-cause mortality has changed with respect to development status can identify exemplars for best practice. To accomplish this, the Global Burden of Diseases, Injuries, and Risk Factors Study 2016 (GBD 2016) estimated age-specific and sex-specific all-cause mortality between 1970 and 2016 for 195 countries and territories and at the subnational level for the five countries with a population greater than 200 million in 2016.
METHODS: We have evaluated how well civil registration systems captured deaths using a set of demographic methods called death distribution methods for adults and from consideration of survey and census data for children younger than 5 years. We generated an overall assessment of completeness of registration of deaths by dividing registered deaths in each location-year by our estimate of all-age deaths generated from our overall estimation process. For 163 locations, including subnational units in countries with a population greater than 200 million with complete vital registration (VR) systems, our estimates were largely driven by the observed data, with corrections for small fluctuations in numbers and estimation for recent years where there were lags in data reporting (lags were variable by location, generally between 1 year and 6 years). For other locations, we took advantage of different data sources available to measure under-5 mortality rates (U5MR) using complete birth histories, summary birth histories, and incomplete VR with adjustments; we measured adult mortality rate (the probability of death in individuals aged 15-60 years) using adjusted incomplete VR, sibling histories, and household death recall. We used the U5MR and adult mortality rate, together with crude death rate due to HIV in the GBD model life table system, to estimate age-specific and sex-specific death rates for each location-year. Using various international databases, we identified fatal discontinuities, which we defined as increases in the death rate of more than one death per million, resulting from conflict and terrorism, natural disasters, major transport or technological accidents, and a subset of epidemic infectious diseases; these were added to estimates in the relevant years. In 47 countries with an identified peak adult prevalence for HIV/AIDS of more than 0·5% and where VR systems were less than 65% complete, we informed our estimates of age-sex-specific mortality using the Estimation and Projection Package (EPP)-Spectrum model fitted to national HIV/AIDS prevalence surveys and antenatal clinic serosurveillance systems. We estimated stillbirths, early neonatal, late neonatal, and childhood mortality using both survey and VR data in spatiotemporal Gaussian process regression models. We estimated abridged life tables for all location-years using age-specific death rates. We grouped locations into development quintiles based on the Socio-demographic Index (SDI) and analysed mortality trends by quintile. Using spline regression, we estimated the expected mortality rate for each age-sex group as a function of SDI. We identified countries with higher life expectancy than expected by comparing observed life expectancy to anticipated life expectancy on the basis of development status alone.
FINDINGS: Completeness in the registration of deaths increased from 28% in 1970 to a peak of 45% in 2013; completeness was lower after 2013 because of lags in reporting. Total deaths in children younger than 5 years decreased from 1970 to 2016, and slower decreases occurred at ages 5-24 years. By contrast, numbers of adult deaths increased in each 5-year age bracket above the age of 25 years. The distribution of annualised rates of change in age-specific mortality rate differed over the period 2000 to 2016 compared with earlier decades: increasing annualised rates of change were less frequent, although rising annualised rates of change still occurred in some locations, particularly for adolescent and younger adult age groups. Rates of stillbirths and under-5 mortality both decreased globally from 1970. Evidence for global convergence of death rates was mixed; although the absolute difference between age-standardised death rates narrowed between countries at the lowest and highest levels of SDI, the ratio of these death rates-a measure of relative inequality-increased slightly. There was a strong shift between 1970 and 2016 toward higher life expectancy, most noticeably at higher levels of SDI. Among countries with populations greater than 1 million in 2016, life expectancy at birth was highest for women in Japan, at 86·9 years (95% UI 86·7-87·2), and for men in Singapore, at 81·3 years (78·8-83·7) in 2016. Male life expectancy was generally lower than female life expectancy between 1970 and 2016, an
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