232 research outputs found
The UCSD Radio-Selected Quasar Survey for Damped Lyman alpha System
As large optical quasar surveys for damped Lya become a reality and the study
of star forming gas in the early Universe achieves statistical robustness, it
is now vital to identify and quantify the sources of systematic error. Because
the nature of optically-selected quasar surveys makes them vulnerable to dust
obscuration, we have undertaken a radio-selected quasar survey for damped Lya
systems to address this bias. We present the definition and results of this
survey. We then combine our sample with the CORALS dataset to investigate the
HI column density distribution function f(N) of damped Lya systems toward
radio-selected quasars. We find that f(N) is well fit by a power-law f(N) = k_1
N^alpha_1, with log k_1 = 22.90 and alpha_1 = -2.18. This power-law is in
excellent agreement with that of optically-selected samples at low N(HI), an
important yet expected result given that obscuration should have negligible
effect at these gas columns. However, because of the relatively small size of
the radio-selected sample, 26 damped Lya systems in 119 quasars, f(N) is not
well constrained at large N(HI) and the first moment of the HI distribution
function, Omega_g, is, strictly speaking, a lower limit. The power-law is steep
enough, however, that extrapolating it to higher column densities implies only
a modest, logarithmic increase in Omega_g. The radio-selected value of Omega_g
= 1.15 x 10^-3, agrees well with the results of optically-selected surveys.
While our results indicate that dust obscuration is likely not a major issue
for surveys of damped Lya systems, we estimate that a radio-selected sample of
approximately 100 damped Lya systems will be required to obtain the precision
necessary to absolutely confirm an absence of dust bias.Comment: 12 pages, 9 Figures. Accepted to ApJ April 11, 200
Sitting Time and Waist Circumference Are Associated With Glycemia in U.K. South Asians: Data from 1,228 adults screened for the PODOSA trial
OBJECTIVE-To investigate the independent contributions of waist circumference, physical activity, and sedentary behavior on glycemia in South Asians living in Scotland. RESEARCH DESIGN AND METHODS-Participants were 1,228 (523 men and 705 women) adults of Indian or Pakistani origin screened for the Prevention of Type 2 Diabetes and Obesity in South Asians (PODOSA) trial. All undertook an oral glucose tolerance test, had physical activity and sitting time assessed by International Physical Activity Questionnaire, and had waist circumference measured. RESULTS-Mean +/- SD age and waist circumference were 49.8 +/- 10.1 years and 99.2 +/- 10.2 cm, respectively. One hundred ninety-one participants had impaired fasting glycemia or impaired glucose tolerance, and 97 had possible type 2 diabetes. In multivariate regression analysis, ay (0.012 mmol.L-1.year [95% CI 0.006-0.017]) and waist circumference (0.018 mmol.L-1.cm(-1) [0.012-0.024]) were significantly independently associated with fasting glucose concentration, and age (0.032 mmol.L-1.year(-1) [0.016-0.049]), waist (0.057 mmolL(-1).cm(-1) [0.040-0.074]), and sitting time (0.097 mmol.L-1.h(-1).day(-1) [0.036-0.158]) were significantly independently associated with 2-h glucose concentration. Vigorous activity time had a borderline significant association with 2-h glucose concentration (-0.819 mmol.L-1.h(-1).day-1 [-1.672 to 0.034]) in the multivariate model. CONCLUSIONS-These data highlight an important relationship between sitting time and 2-h glucose levels in U.K. South Asians, independent of physical activity and waist circumference. Although the data are cross-sectional and thus do not permit firm conclusions about causality to be drawn, the results suggest that further study investigating the effects of sitting time on glycemia and other aspects of metabolic risk in South Asian populations is warrante
Associations between diffusion MRI microstructure and cerebrospinal fluid markers of Alzheimer's disease pathology and neurodegeneration along the Alzheimer's disease continuum
INTRODUCTION: White matter (WM) degeneration is a critical component of early Alzheimer's disease (AD) pathophysiology. Diffusion-weighted imaging (DWI) models, including diffusion tensor imaging (DTI), neurite orientation dispersion and density imaging (NODDI), and mean apparent propagator MRI (MAP-MRI), have the potential to identify early neurodegenerative WM changes associated with AD. METHODS: We imaged 213 (198 cognitively unimpaired) aging adults with DWI and used tract-based spatial statistics to compare 15 DWI metrics of WM microstructure to 9 cerebrospinal fluid (CSF) markers of AD pathology and neurodegeneration treated as continuous variables. RESULTS: We found widespread WM injury in AD, as indexed by robust associations between DWI metrics and CSF biomarkers. MAP-MRI had more spatially diffuse relationships with Aβ42/40 and pTau, compared with NODDI and DTI. DISCUSSION: Our results suggest that WM degeneration may be more pervasive in AD than is commonly appreciated and that innovative DWI models such as MAP-MRI may provide clinically viable biomarkers of AD-related neurodegeneration in the earliest stages of AD progression
Dust depletion, chemical uniformity and environment of CaII H&K quasar absorbers
CaII 3934,3969 absorbers, which are likely to be a subset of damped Lyman
alpha systems, are the most dusty quasar absorbers known, with an order of
magnitude more extinction in E(B-V) than other absorption systems. There is
also evidence that CaII absorbers trace galaxies with more ongoing
star-formation than the average quasar absorber. Despite this, relatively
little is known in detail about these unusual absorption systems. Here we
present the first high resolution spectroscopic study of 19 CaII quasar
absorbers, in the range 0.6=0.2A. Their general
depletion patterns are similar to measurements in the warm halo phase of the
Milky Way and Magellanic Clouds ISM. Dust depletions and alpha-enrichments
profiles of sub-samples of 7 and 3 absorbers, respectively, are measured using
a combination of Voigt profile fitting and apparent optical depth techniques.
Deviations in [Cr/Zn]~0.3+-0.1dex and in [Si/Fe]>~0.8+-0.1dex are detected
across the profile of one absorber, which we attribute to differential dust
depletion. The remaining absorbers have <0.3dex (3sigma limit) variation in
[Cr/Zn], much like the general DLA population, though the dustiest CaII
absorbers remain relatively unprobed in our sample. A limit on electron
densities in CaII absorbers, n_e<0.1cm^-3, is derived using the ratio of
neutral and singly ionised species, assuming a MW-like radiation field. These
electron densities may imply hydrogen densities sufficient for the presence of
molecular hydrogen in the absorbers. The CaII absorber sample comprises a wide
range of velocity widths, v_90=50-470km/s, and velocity structures, thus a
range of physical models for their origin, from simple discs to galactic
outflows and mergers, would be required to explain the observations.Comment: Minor revision after publication proofs to ensure arXiv version of
paper matches MNRAS published versio
Gender differences in the association between adiposity and probable major depression: a cross-sectional study of 140,564 UK Biobank participants
<b>Background</b><p></p>
Previous studies on the association between adiposity and mood disorder have produced contradictory results, and few have used measurements other than body mass index (BMI). We examined the association between probable major depression and several measurements of adiposity: BMI, waist circumference (WC), waist-hip-ratio (WHR), and body fat percentage (BF%).<p></p>
<b>Methods</b><p></p>
We conducted a cross-sectional study using baseline data on the sub-group of UK Biobank participants who were assessed for mood disorder. Multivariate logistic regression models were used, adjusting for potential confounders including: demographic and life-style factors, comorbidity and psychotropic medication.<p></p>
<b>Results</b><p></p>
Of the 140,564 eligible participants, evidence of probable major depression was reported by 30,145 (21.5%). The fully adjusted odds ratios (OR) for obese participants were 1.16 (95% confidence interval (CI) 1.12, 1.20) using BMI, 1.15 (95% CI 1.11, 1.19) using WC, 1.09 (95% CI 1.05, 1.13) using WHR and 1.18 (95% CI 1.12, 1.25) using BF% (all p <0.001). There was a significant interaction between adiposity and gender (p = 0.001). Overweight women were at increased risk of depression with a dose response relationship across the overweight (25.0-29.9 kg/m2), obese I (30.0-34.9 kg/m2), II (35.0-39.9 kg/m2) and III (≥40.0 kg/m2) categories; fully adjusted ORs 1.14, 1.20, 1.29 and 1.48, respectively (all p < 0.001). In contrast, only obese III men had significantly increased risk of depression (OR 1.29, 95% CI 1.08, 1.54, p = 0.006).<p></p>
<b>Conclusion</b><p></p>
Adiposity was associated with probable major depression, irrespective of the measurement used. The association was stronger in women than men. Physicians managing overweight and obese women should be alert to this increased risk
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Access to justice during the COVID-19 pandemic in the UK
The COVID-19 pandemic has presented many challenges for our legal system. The courts have had to adapt to the unprecedented change in circumstances. One of the most dramatic changes to occur was the introduction of remote court hearings. This report, jointly authored by the Open University and Northumbria University, seeks to explore this transition and the impact it has had on access to justice.
The Open University Policy Clinic is part of the Open Justice Centre. Open Justice provides free legal advice and education to members of the public in a variety of legal areas. In 2019, Open Justice established the Policy Clinic to undertake research on behalf of organisations and charities, aiming to influence policy and law reform. The Northumbria Student Law Office was set up in 1981 and offers free legal advice to members of the public on a range of different areas. The Policy Clinic within the Student Law Office was set up in the 2018/2019 academic year with the aim to undertake research influencing policy and law reform.
We began our research by gathering data from a sample of 80 Crown Courts and 77 County Courts. In addition to this, we conducted fieldwork in the Court of Protection. This involved all members of the team requesting access as public observers to remote hearings. In total, 25 hearings were attended. There was also a review of existing literature surrounding remote hearings. This report will identify the themes arising from our research that have a direct influence on access to justice. We will discuss the findings from our research alongside the existing data, and comparisons will be made between these two data sets. We believe this report is particularly important as we enter a post-COVID-19 world and questions are being raised as to whether the changes that have occurred during the pandemic should be implemented permanently. The aim of this report is to gain an insight into the effect of the pandemic and to assess the practicality of online courts
The Fourteenth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the extended Baryon Oscillation Spectroscopic Survey and from the second phase of the Apache Point Observatory Galactic Evolution Experiment
The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) has been in
operation since July 2014. This paper describes the second data release from
this phase, and the fourteenth from SDSS overall (making this, Data Release
Fourteen or DR14). This release makes public data taken by SDSS-IV in its first
two years of operation (July 2014-2016). Like all previous SDSS releases, DR14
is cumulative, including the most recent reductions and calibrations of all
data taken by SDSS since the first phase began operations in 2000. New in DR14
is the first public release of data from the extended Baryon Oscillation
Spectroscopic Survey (eBOSS); the first data from the second phase of the
Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE-2),
including stellar parameter estimates from an innovative data driven machine
learning algorithm known as "The Cannon"; and almost twice as many data cubes
from the Mapping Nearby Galaxies at APO (MaNGA) survey as were in the previous
release (N = 2812 in total). This paper describes the location and format of
the publicly available data from SDSS-IV surveys. We provide references to the
important technical papers describing how these data have been taken (both
targeting and observation details) and processed for scientific use. The SDSS
website (www.sdss.org) has been updated for this release, and provides links to
data downloads, as well as tutorials and examples of data use. SDSS-IV is
planning to continue to collect astronomical data until 2020, and will be
followed by SDSS-V.Comment: SDSS-IV collaboration alphabetical author data release paper. DR14
happened on 31st July 2017. 19 pages, 5 figures. Accepted by ApJS on 28th Nov
2017 (this is the "post-print" and "post-proofs" version; minor corrections
only from v1, and most of errors found in proofs corrected
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