66 research outputs found
The DDO IVC Distance Project: Survey Description and the Distance to G139.6+47.6
We present a detailed analysis of the distance determination for one
intermediate Velocity Cloud (IVC G139.6+47.6) from the ongoing DDO IVC Distance
Project. Stars along the line of sight to G139.6+47.6 are examined for the
presence of sodium absorption attributable to the cloud, and the distance
bracket is established by astrometric and spectroscopic parallax measurements
of demonstrated foreground and background stars. We detail our strategy
regarding target selection, observational setup, and analysis of the data,
including a discussion of wavelength calibration and sky subtraction
uncertainties. We find a distance estimate of 129 (+/- 10) pc for the lower
limit and 257 (+211-33) pc for the upper limit. Given the high number of stars
showing absorption due to this IVC, we also discuss the small-scale covering
factor of the cloud and the likely significance of non-detections for
subsequent observations of this and other similar IVC's. Distance measurements
of the remaining targets in the DDO IVC project will be detailed in a companion
paper.Comment: 10 pages, 6 figures, LaTe
Beta Amyloid Deposition Is Not Associated With Cognitive Impairment in Parkinson's Disease
The extent to which Alzheimer neuropathology, particularly the accumulation of misfolded beta-amyloid, contributes to cognitive decline and dementia in Parkinson's disease (PD) is unresolved. Here, we used Florbetaben PET imaging to test for any association between cerebral amyloid deposition and cognitive impairment in PD, in a sample enriched for cases with mild cognitive impairment. This cross-sectional study used Movement Disorders Society level II criteria to classify 115 participants with PD as having normal cognition (PDN, n = 23), mild cognitive impairment (PD-MCI, n = 76), or dementia (PDD, n = 16). We acquired 18F-Florbetaben (FBB) amyloid PET and structural MRI. Amyloid deposition was assessed between the three cognitive groups, and also across the whole sample using continuous measures of both global cognitive status and average performance in memory domain tests. Outcomes were cortical FBB uptake, expressed in centiloids and as standardized uptake value ratios (SUVR) using the Centiloid Project whole cerebellum region as a reference, and regional SUVR measurements. FBB binding was higher in PDD, but this difference did not survive adjustment for the older age of the PDD group. We established a suitable centiloid cut-off for amyloid positivity in Parkinson's disease (31.3), but there was no association of FBB binding with global cognitive or memory scores. The failure to find an association between PET amyloid deposition and cognitive impairment in a moderately large sample, particularly given that it was enriched with PD-MCI patients at risk of dementia, suggests that amyloid pathology is not the primary driver of cognitive impairment and dementia in most patients with PD
JWST reveals a possible galaxy merger in triply-lensed MACS0647JD
MACS0647JD is a triply-lensed galaxy originally discovered with
the Hubble Space Telescope. Here we report new JWST imaging, which clearly
resolves MACS0647JD as having two components that are either merging
galaxies or stellar complexes within a single galaxy. Both are very small, with
stellar masses and radii . The brighter
larger component "A" is intrinsically very blue (), likely due
to very recent star formation and no dust, and is spatially extended with an
effective radius . The smaller component "B" appears redder
(), likely because it is older () with mild dust
extinction (), and a smaller radius . We
identify galaxies with similar colors in a high-redshift simulation, finding
their star formation histories to be out of phase. With an estimated stellar
mass ratio of roughly 2:1 and physical projected separation ,
we may be witnessing a galaxy merger 400 million years after the Big Bang. We
also identify a candidate companion galaxy C away, likely
destined to merge with galaxies A and B. The combined light from galaxies A+B
is magnified by factors of 8, 5, and 2 in three lensed images JD1, 2, and
3 with F356W fluxes , , (AB mag 25.1, 25.6, 26.6).
MACS0647JD is significantly brighter than other galaxies recently discovered
at similar redshifts with JWST. Without magnification, it would have AB mag
27.3 (). With a high confidence level, we obtain a photometric
redshift of based on photometry measured in 6 NIRCam filters
spanning , out to rest-frame. JWST NIRSpec
observations planned for January 2023 will deliver a spectroscopic redshift and
a more detailed study of the physical properties of MACS0647JD.Comment: 27 pages, 14 figures, submitted to Natur
Genetic variants in novel pathways influence blood pressure and cardiovascular disease risk.
Blood pressure is a heritable trait influenced by several biological pathways and responsive to environmental stimuli. Over one billion people worldwide have hypertension (≥140 mm Hg systolic blood pressure or ≥90 mm Hg diastolic blood pressure). Even small increments in blood pressure are associated with an increased risk of cardiovascular events. This genome-wide association study of systolic and diastolic blood pressure, which used a multi-stage design in 200,000 individuals of European descent, identified sixteen novel loci: six of these loci contain genes previously known or suspected to regulate blood pressure (GUCY1A3-GUCY1B3, NPR3-C5orf23, ADM, FURIN-FES, GOSR2, GNAS-EDN3); the other ten provide new clues to blood pressure physiology. A genetic risk score based on 29 genome-wide significant variants was associated with hypertension, left ventricular wall thickness, stroke and coronary artery disease, but not kidney disease or kidney function. We also observed associations with blood pressure in East Asian, South Asian and African ancestry individuals. Our findings provide new insights into the genetics and biology of blood pressure, and suggest potential novel therapeutic pathways for cardiovascular disease prevention
GA4GH: International policies and standards for data sharing across genomic research and healthcare.
The Global Alliance for Genomics and Health (GA4GH) aims to accelerate biomedical advances by enabling the responsible sharing of clinical and genomic data through both harmonized data aggregation and federated approaches. The decreasing cost of genomic sequencing (along with other genome-wide molecular assays) and increasing evidence of its clinical utility will soon drive the generation of sequence data from tens of millions of humans, with increasing levels of diversity. In this perspective, we present the GA4GH strategies for addressing the major challenges of this data revolution. We describe the GA4GH organization, which is fueled by the development efforts of eight Work Streams and informed by the needs of 24 Driver Projects and other key stakeholders. We present the GA4GH suite of secure, interoperable technical standards and policy frameworks and review the current status of standards, their relevance to key domains of research and clinical care, and future plans of GA4GH. Broad international participation in building, adopting, and deploying GA4GH standards and frameworks will catalyze an unprecedented effort in data sharing that will be critical to advancing genomic medicine and ensuring that all populations can access its benefits
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
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