84 research outputs found
New sub-millimeter limits on dust in the 55 Cancri planetary system
We present new, high-sensitivity sub-millimeter observations towards 55
Cancri, a nearby G8 star with one, or possibly two, known planetary
companion(s). Our 850 m map, obtained with the SCUBA instrument on the
James Clerk Maxwell Telescope, shows three peaks of emission at the 2.5 mJy
level in the vicinity of the star's position. However, the observed peaks are
25\arcsec--40\arcsec away from the star and a deep -band optical image
reveals faint point sources that coincide with two of the sub-millimeter peaks.
Thus, we do not find evidence for dust emission spatially associated with 55
Cancri. The excess 60 m emission detected with ISO may originate from one
or more of the 850 m peaks that we attribute to background sources. Our
new results, together with the HST/NICMOS coronographic images in the
near-infrared, place stringent limits on the amount of dust in this planetary
system, and argue against the existence of a detectable circumstellar dust disk
around 55 Cnc.Comment: 11 pages, 2 PostScript figures, to appear in The Astrophysical
Journal Letter
Dust in the 55 Cancri planetary system
The presence of debris disks around 1-Gyr-old main sequence stars
suggests that an appreciable amount of dust may persist even in mature
planetary systems. Here we report the detection of dust emission from 55
Cancri, a star with one, or possibly two, planetary companions detected through
radial velocity measurements. Our observations at 850m and 450m imply
a dust mass of 0.0008-0.005 Earth masses, somewhat higher than that in the the
Kuiper Belt of our solar system. The estimated temperature of the dust grains
and a simple model fit both indicate a central disk hole of at least 10 AU in
radius. Thus, the region where the planets are detected is likely to be
significantly depleted of dust. Our results suggest that far-infrared and
sub-millimeter observations are powerful tools for probing the outer regions of
extrasolar planetary systems.Comment: 8 pages and 2 figures, to appear in the Astrophysical Journa
Spectrum of HLA associations: the case of medically refractory pediatric acute lymphoblastic leukemia
Although studies of HLA and disease now date back some 50 years, a principled understanding of that relationship has been slow to emerge. Here, we examine the associations of three HLA loci with medically refractory pediatric acute lymphoblastic leukemia (pALL) patients in a case–control study involving 2,438 cases and 41,750 controls. An analysis of alleles from the class I loci, HLA-A and HLA-B, and the class II locus DRB1 illuminates a spectrum of extremely significant allelic associations conferring both predisposition and protection. Genotypes constructed from predisposing, protective, and neutral allelic categories point to an additive mode of disease causation. For all three loci, genotypes homozygous for predisposing alleles are at highest disease risk while the favorable effect of homozygous protective genotypes is less striking. Analysis of A–B and B–DRB1 haplotypes reveals locus-specific differences in disease effects, while that all three loci influence pALL; the influence of HLA-B is greater than that of HLA-A, and the predisposing effect of DRB1 exceeds that of HLA-B. We propose that the continuum in disease susceptibility suggests a system in which many alleles take part in disease predisposition based on differences in binding affinity to one or a few peptides of exogenous origin. This work provides evidence that an immune response mediated by alleles from several HLA loci plays a critical role in the pathogenesis of pALL, adding to the numerous studies pointing to a role for an infectious origin in pALL
An Unbiased Survey of 500 Nearby Stars for Debris Disks: A JCMT Legacy Program
We present the scientific motivation and observing plan for an upcoming
detection survey for debris disks using the James Clerk Maxwell Telescope. The
SCUBA-2 Unbiased Nearby Stars (SUNS) Survey will observe 500 nearby main
sequence and sub-giant stars (100 of each of the A, F, G, K and M spectral
classes) to the 850 micron extragalactic confusion limit to search for evidence
of submillimeter excess, an indication of circumstellar material. The survey
distance boundaries are 8.6, 16.5, 22, 25 and 45 pc for M, K, G, F and A stars,
respectively, and all targets lie between the declinations of -40 deg to 80
deg. In this survey, no star will be rejected based on its inherent properties:
binarity, presence of planetary companions, spectral type or age. This will be
the first unbiased survey for debris disks since IRAS. We expect to detect ~125
debris disks, including ~50 cold disks not detectable in current shorter
wavelength surveys. A substantial amount of complementary data will be required
to constrain the temperatures and masses of discovered disks. High resolution
studies will likely be required to resolve many of the disks. Therefore, these
systems will be the focus of future observational studies using a variety of
observatories to characterize their physical properties. For non-detected
systems, this survey will set constraints (upper limits) on the amount of
circumstellar dust, of typically 200 times the Kuiper Belt mass, but as low as
10 times the Kuiper Belt mass for the nearest stars in the sample
(approximately 2 pc).Comment: 11 pages, 7 figures (3 color), accepted by the Publications of the
Astronomical Society of the Pacifi
Dust Populations in the Iconic Vega Planetary System Resolved by ALMA
The Vega planetary system hosts the archetype of extrasolar Kuiper belts, and
is rich in dust from the sub-au region out to 100's of au, suggesting intense
dynamical activity. We present ALMA mm observations that detect and resolve the
outer dust belt from the star for the first time. The interferometric
visibilities show that the belt can be fit by a Gaussian model or by power-law
models with a steep inner edge (at 60-80 au). The belt is very broad, extending
out to at least 150-200 au. We strongly detect the star and set a stringent
upper limit to warm dust emission previously detected in the infrared. We
discuss three scenarios that could explain the architecture of Vega's planetary
system, including the new {ALMA} constraints: no outer planets, a chain of
low-mass planets, and a single giant planet. The planet-less scenario is only
feasible if the outer belt was born with the observed sharp inner edge. If
instead the inner edge is currently being truncated by a planet, then the
planet must be 6 M and at au to have cleared
its chaotic zone within the system age. In the planet chain scenario, outward
planet migration and inward scattering of planetesimals could produce the hot
and warm dust observed in the inner regions of the system. In the single giant
planet scenario, an asteroid belt could be responsible for the warm dust, and
mean motion resonances with the planet could put asteroids on star-grazing
orbits, producing the hot dust.Comment: 18 pages, 3 figures, Accepted for publication in Ap
Impact of vaccination on the association of COVID-19 with cardiovascular diseases:An OpenSAFELY cohort study
Infection with SARS-CoV-2 is associated with an increased risk of arterial and venous thrombotic events, but the implications of vaccination for this increased risk are uncertain. With the approval of NHS England, we quantified associations between COVID-19 diagnosis and cardiovascular diseases in different vaccination and variant eras using linked electronic health records for ~40% of the English population. We defined a 'pre-vaccination' cohort (18,210,937 people) in the wild-type/Alpha variant eras (January 2020-June 2021), and 'vaccinated' and 'unvaccinated' cohorts (13,572,399 and 3,161,485 people respectively) in the Delta variant era (June-December 2021). We showed that the incidence of each arterial thrombotic, venous thrombotic and other cardiovascular outcomes was substantially elevated during weeks 1-4 after COVID-19, compared with before or without COVID-19, but less markedly elevated in time periods beyond week 4. Hazard ratios were higher after hospitalised than non-hospitalised COVID-19 and higher in the pre-vaccination and unvaccinated cohorts than the vaccinated cohort. COVID-19 vaccination reduces the risk of cardiovascular events after COVID-19 infection. People who had COVID-19 before or without being vaccinated are at higher risk of cardiovascular events for at least two years.</p
The degree of segmental aneuploidy measured by total copy number abnormalities predicts survival and recurrence in superficial gastroesophageal adenocarcinoma
Background: Prognostic biomarkers are needed for superficial gastroesophageal adenocarcinoma (EAC) to predict clinical outcomes and select therapy. Although recurrent mutations have been characterized in EAC, little is known about their clinical and prognostic significance. Aneuploidy is predictive of clinical outcome in many malignancies but has not been evaluated in superficial EAC. Methods: We quantified copy number changes in 41 superficial EAC using Affymetrix SNP 6.0 arrays. We identified recurrent chromosomal gains and losses and calculated the total copy number abnormality (CNA) count for each tumor as a measure of aneuploidy. We correlated CNA count with overall survival and time to first recurrence in univariate and multivariate analyses. Results: Recurrent segmental gains and losses involved multiple genes, including: HER2, EGFR, MET, CDK6, KRAS (recurrent gains); and FHIT, WWOX, CDKN2A/B, SMAD4, RUNX1 (recurrent losses). There was a 40-fold variation in CNA count across all cases. Tumors with the lowest and highest quartile CNA count had significantly better overall survival (p = 0.032) and time to first recurrence (p = 0.010) compared to those with intermediate CNA counts. These associations persisted when controlling for other prognostic variables. Significance: SNP arrays facilitate the assessment of recurrent chromosomal gain and loss and allow high resolution, quantitative assessment of segmental aneuploidy (total CNA count). The non-monotonic association of segmental aneuploidy with survival has been described in other tumors. The degree of aneuploidy is a promising prognostic biomarker in a potentially curable form of EAC. © 2014 Davison et al
Re-evaluating syndicalist opposition to the First World War
It has been argued that support for the First World War by the important French syndicalist organisation, the Confédération Générale du Travail (CGT) has tended to obscure the fact that other national syndicalist organisations remained faithful to their professed workers’ internationalism: on this basis syndicalists beyond France, more than any other ideological persuasion within the organised trade union movement in immediate pre-war and wartime Europe, can be seen to have constituted an authentic movement of opposition to the war in their refusal to subordinate class interests to those of the state, to endorse policies of ‘defencism’ of the ‘national interest’ and to abandon the rhetoric of class conflict. This article, which attempts to contribute to a much neglected comparative historiography of the international syndicalist movement, re-evaluates the syndicalist response across a broad geographical field of canvas (embracing France, Italy, Spain, Ireland, Britain and America) to reveal a rather more nuanced, ambiguous and uneven picture. While it highlights the distinctive nature of the syndicalist response compared with other labour movement trends, it also explores the important strategic and tactical limitations involved, including the dilemma of attempting to translate formal syndicalist ideological commitments against the war into practical measures of intervention, and the consequences of the syndicalists’ subordination of the political question of the war to the industrial struggle
Global burden of 369 diseases and injuries in 204 countries and territories, 1990–2019: a systematic analysis for the Global Burden of Disease Study 2019
Background: In an era of shifting global agendas and expanded emphasis on non-communicable diseases and injuries along with communicable diseases, sound evidence on trends by cause at the national level is essential. The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) provides a systematic scientific assessment of published, publicly available, and contributed data on incidence, prevalence, and mortality for a mutually exclusive and collectively exhaustive list of diseases and injuries. Methods: GBD estimates incidence, prevalence, mortality, years of life lost (YLLs), years lived with disability (YLDs), and disability-adjusted life-years (DALYs) due to 369 diseases and injuries, for two sexes, and for 204 countries and territories. Input data were extracted from censuses, household surveys, civil registration and vital statistics, disease registries, health service use, air pollution monitors, satellite imaging, disease notifications, and other sources. Cause-specific death rates and cause fractions were calculated using the Cause of Death Ensemble model and spatiotemporal Gaussian process regression. Cause-specific deaths were adjusted to match the total all-cause deaths calculated as part of the GBD population, fertility, and mortality estimates. Deaths were multiplied by standard life expectancy at each age to calculate YLLs. A Bayesian meta-regression modelling tool, DisMod-MR 2.1, was used to ensure consistency between incidence, prevalence, remission, excess mortality, and cause-specific mortality for most causes. Prevalence estimates were multiplied by disability weights for mutually exclusive sequelae of diseases and injuries to calculate YLDs. We considered results in the context of the Socio-demographic Index (SDI), a composite indicator of income per capita, years of schooling, and fertility rate in females younger than 25 years. Uncertainty intervals (UIs) were generated for every metric using the 25th and 975th ordered 1000 draw values of the posterior distribution. Findings: Global health has steadily improved over the past 30 years as measured by age-standardised DALY rates. After taking into account population growth and ageing, the absolute number of DALYs has remained stable. Since 2010, the pace of decline in global age-standardised DALY rates has accelerated in age groups younger than 50 years compared with the 1990–2010 time period, with the greatest annualised rate of decline occurring in the 0–9-year age group. Six infectious diseases were among the top ten causes of DALYs in children younger than 10 years in 2019: lower respiratory infections (ranked second), diarrhoeal diseases (third), malaria (fifth), meningitis (sixth), whooping cough (ninth), and sexually transmitted infections (which, in this age group, is fully accounted for by congenital syphilis; ranked tenth). In adolescents aged 10–24 years, three injury causes were among the top causes of DALYs: road injuries (ranked first), self-harm (third), and interpersonal violence (fifth). Five of the causes that were in the top ten for ages 10–24 years were also in the top ten in the 25–49-year age group: road injuries (ranked first), HIV/AIDS (second), low back pain (fourth), headache disorders (fifth), and depressive disorders (sixth). In 2019, ischaemic heart disease and stroke were the top-ranked causes of DALYs in both the 50–74-year and 75-years-and-older age groups. Since 1990, there has been a marked shift towards a greater proportion of burden due to YLDs from non-communicable diseases and injuries. In 2019, there were 11 countries where non-communicable disease and injury YLDs constituted more than half of all disease burden. Decreases in age-standardised DALY rates have accelerated over the past decade in countries at the lower end of the SDI range, while improvements have started to stagnate or even reverse in countries with higher SDI. Interpretation: As disability becomes an increasingly large component of disease burden and a larger component of health expenditure, greater research and developm nt investment is needed to identify new, more effective intervention strategies. With a rapidly ageing global population, the demands on health services to deal with disabling outcomes, which increase with age, will require policy makers to anticipate these changes. The mix of universal and more geographically specific influences on health reinforces the need for regular reporting on population health in detail and by underlying cause to help decision makers to identify success stories of disease control to emulate, as well as opportunities to improve. Funding: Bill & Melinda Gates Foundation. © 2020 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 licens
Global age-sex-specific fertility, mortality, healthy life expectancy (HALE), and population estimates in 204 countries and territories, 1950-2019 : a comprehensive demographic analysis for the Global Burden of Disease Study 2019
Background: Accurate and up-to-date assessment of demographic metrics is crucial for understanding a wide range of social, economic, and public health issues that affect populations worldwide. The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 produced updated and comprehensive demographic assessments of the key indicators of fertility, mortality, migration, and population for 204 countries and territories and selected subnational locations from 1950 to 2019.
Methods: 8078 country-years of vital registration and sample registration data, 938 surveys, 349 censuses, and 238 other sources were identified and used to estimate age-specific fertility. Spatiotemporal Gaussian process regression (ST-GPR) was used to generate age-specific fertility rates for 5-year age groups between ages 15 and 49 years. With extensions to age groups 10–14 and 50–54 years, the total fertility rate (TFR) was then aggregated using the estimated age-specific fertility between ages 10 and 54 years. 7417 sources were used for under-5 mortality estimation and 7355 for adult mortality. ST-GPR was used to synthesise data sources after correction for known biases. Adult mortality was measured as the probability of death between ages 15 and 60 years based on vital registration, sample registration, and sibling histories, and was also estimated using ST-GPR. HIV-free life tables were then estimated using estimates of under-5 and adult mortality rates using a relational model life table system created for GBD, which closely tracks observed age-specific mortality rates from complete vital registration when available. Independent estimates of HIV-specific mortality generated by an epidemiological analysis of HIV prevalence surveys and antenatal clinic serosurveillance and other sources were incorporated into the estimates in countries with large epidemics. Annual and single-year age estimates of net migration and population for each country and territory were generated using a Bayesian hierarchical cohort component model that analysed estimated age-specific fertility and mortality rates along with 1250 censuses and 747 population registry years. We classified location-years into seven categories on the basis of the natural rate of increase in population (calculated by subtracting the crude death rate from the crude birth rate) and the net migration rate. We computed healthy life expectancy (HALE) using years lived with disability (YLDs) per capita, life tables, and standard demographic methods. Uncertainty was propagated throughout the demographic estimation process, including fertility, mortality, and population, with 1000 draw-level estimates produced for each metric. Findings: The global TFR decreased from 2·72 (95% uncertainty interval [UI] 2·66–2·79) in 2000 to 2·31 (2·17–2·46) in 2019. Global annual livebirths increased from 134·5 million (131·5–137·8) in 2000 to a peak of 139·6 million (133·0–146·9) in 2016. Global livebirths then declined to 135·3 million (127·2–144·1) in 2019. Of the 204 countries and territories included in this study, in 2019, 102 had a TFR lower than 2·1, which is considered a good approximation of replacement-level fertility. All countries in sub-Saharan Africa had TFRs above replacement level in 2019 and accounted for 27·1% (95% UI 26·4–27·8) of global livebirths. Global life expectancy at birth increased from 67·2 years (95% UI 66·8–67·6) in 2000 to 73·5 years (72·8–74·3) in 2019. The total number of deaths increased from 50·7 million (49·5–51·9) in 2000 to 56·5 million (53·7–59·2) in 2019. Under-5 deaths declined from 9·6 million (9·1–10·3) in 2000 to 5·0 million (4·3–6·0) in 2019. Global population increased by 25·7%, from 6·2 billion (6·0–6·3) in 2000 to 7·7 billion (7·5–8·0) in 2019. In 2019, 34 countries had negative natural rates of increase; in 17 of these, the population declined because immigration was not sufficient to counteract the negative rate of decline. Globally, HALE increased from 58·6 years (56·1–60·8) in 2000 to 63·5 years (60·8–66·1) in 2019. HALE increased in 202 of 204 countries and territories between 2000 and 2019
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