4,818 research outputs found
High precision microlensing maps of the Galactic bulge
We present detailed maps of the microlensing optical depth and event density
over an area of 195 sq. deg towards the Galactic bulge. The maps are computed
from synthetic stellar catalogues generated from the Besancon Galaxy Model,
which comprises four stellar populations and a three-dimensional extinction map
calibrated against the Two-Micron All-Sky Survey. The optical depth maps have a
resolution of 15 arcminutes, corresponding to the angular resolution of the
extinction map. We compute optical depth and event density maps for all
resolved sources above I=19, for unresolved (difference image) sources
magnified above this limit, and for bright standard candle sources in the
bulge. We show that the resulting optical depth contours are dominated by
extinction effects, exhibiting fine structure in stark contrast to previous
theoretical optical depth maps. Optical depth comparisons between Galactic
models and optical microlensing survey measurements cannot safely ignore
extinction or assume it to be smooth. We show how the event distribution for
hypothetical J and K-band microlensing surveys, using existing ground-based
facilities such as VISTA, UKIRT or CFHT, would be much less affected by
extinction, especially in the K band. The near infrared provides a substantial
sensitivity increase over current I-band surveys and a more faithful tracer of
the underlying stellar distribution, something which upcoming variability
surveys such as VVV will be able to exploit. Synthetic population models offer
a promising way forward to fully exploit large microlensing datasets for
Galactic structure studies.Comment: 8 pages, submitted to MNRA
Space Velocities of L- and T-type Dwarfs
(Abridged) We have obtained radial velocities of a sample of 18 ultracool
dwarfs (M6.5-T8) using high-resolution, near-infrared spectra obtained with
NIRSPEC and the Keck II telescope. We have confirmed that the radial velocity
of Gl 570 D is coincident with that of the K-type primary star Gl 570 A, thus
providing additional support for their true companionship. The presence of
planetary-mass companions around 2MASS J05591914-1404488 (T4.5V) has been
analyzed using five NIRSPEC radial velocity measurements obtained over a period
of 4.37 yr. We have computed UVW space motions for a total of 21 L and T dwarfs
within 20 pc of the Sun. This population shows UVW velocities that nicely
overlap the typical kinematics of solar to M-type stars within the same spatial
volume. However, the mean Galactic (44.2 km/s) and tangential (36.5 km/s)
velocities of the L and T dwarfs appear to be smaller than those of G to M
stars. A significant fraction (~40%) of the L and T dwarfs lies near the Hyades
moving group (0.4-2 Gyr), which contrasts with the 10-12% found for
earlier-type stellar neighbors. Additionally, the distributions of all three
UVW components (sigma_{UVW} = 30.2, 16.5, 15.8 km/s) and the distributions of
the total Galactic (sigma_{v_tot} = 19.1 km/s) and tangential (sigma_{v_t} =
17.6 km/s) velocities derived for the L and T dwarf sample are narrower than
those measured for nearby G, K, and M-type stars, but similar to the
dispersions obtained for F stars. This suggests that, in the solar
neighborhood, the L- and T-type ultracool dwarfs in our sample (including brown
dwarfs) is kinematically younger than solar-type to early M stars with likely
ages in the interval 0.5-4 Gyr.Comment: Accepted for publication in Ap
Predicting convective blueshift and radial-velocity dispersion due to granulation for FGK stars
To detect Earth-mass planets using the Doppler method, a major obstacle is to
differentiate the planetary signal from intrinsic stellar variability (e.g.,
pulsations, granulation, spots and plages). Convective blueshift, which results
from small-scale convection at the surface of Sun-like stars, is relevant for
Earth-twin detections as it exhibits Doppler noise on the order of 1 m/s. Here,
we present a simple model for convective blueshift based on fundamental
equations of stellar structure. Our model successfully matches observations of
convective blueshift for FGK stars. Based on our model, we also compute the
intrinsic noise floor for stellar granulation in the radial velocity
observations. We find that for a given mass range, stars with higher
metallicities display lower radial-velocity dispersion due to granulation, in
agreement with MHD simulations. We also provide a set of formulae to predict
the amplitude of radial-velocity dispersion due to granulation as a function of
stellar parameters. Our work is vital in identifying the most amenable stellar
targets for EPRV surveys and radial velocity follow-up programmes for TESS,
CHEOPS, and the upcoming PLATO mission.Comment: 11 pages, 5 figures, 3 tables. Submitted, under revie
The incidence and risk factors for new onset atrial fibrillation in the PROSPER study
Aims Atrial fibrillation/flutter (AF) is the most common arrhythmia in older people. It associates with reduced exercise capacity, increased risk of stroke, and mortality. We aimed to determine retrospectively whether pravastatin reduces the incidence of AF and whether any electrocardiographic measures or clinical conditions might be risk factors for its development. Methods and results The PROspective Study of Pravastatin in the Elderly at Risk (PROSPER) was a randomized, double-blind controlled trial that recruited 5804 individuals aged 70-82 years with a history of, or risk factors for, vascular disease. A total of 2891 were allocated to pravastatin and 2913 to placebo; mean follow-up was 3.2 years. Electrocardiograms (ECGs), which were recorded at baseline, annually thereafter, and at run-out, were processed by computer and reviewed manually. In all, 264 of 2912 (9.1%) of the placebo group and 283 of 2888 (9.8%) of the pravastatin-treated group developed AF [hazard ratio 1.08 (0.92,1.28), P = 0.35)]. Multivariate analysis showed that PR and QTc intervals, age, left ventricular hypertrophy, and ST-T abnormalities were related to development of AF after adjustment for many variables including alcohol consumption, which itself was univariately predictive of developing AF. Previous myocardial infarction on the ECG was not a risk factor. A history of vascular disease was strongly linked with developing AF but not diabetes and hypertension. Conclusion Pravastatin does not reduce the incidence of AF in older people at risk of vascular disease, at least in the short-medium term. Risk factors for AF include older age, prolongation of PR or QTc intervals, left ventricular hypertrophy, and ST-T abnormalities on the EC
Establishing the values for patient engagement (PE) in health-related quality of life (HRQoL) research: an international, multiple-stakeholder perspective
PurposeActive patient engagement is increasingly viewed as essential to ensuring that patient-driven perspectives are considered throughout the research process. However, guidance for patient engagement (PE) in HRQoL research does not exist, the evidence-base for practice is limited, and we know relatively little about underpinning values that can impact on PE practice. This is the first study to explore the values that should underpin PE in contemporary HRQoL research to help inform future good practice guidance. MethodsA modified ‘World Café’ was hosted as a collaborative activity between patient partners, clinicians and researchers: self-nominated conference delegates participated in group discussions to explore values associated with the conduct and consequences of PE. Values were captured via post-it notes and by nominated note-takers. Data were thematically analysed: emergent themes were coded and agreement checked. Association between emergent themes, values and the Public Involvement Impact Assessment Framework were explored. ResultsEighty participants, including 12 patient partners, participated in the 90-min event. Three core values were defined: (1) building relationships; (2) improving research quality and impact; and (3) developing best practice. Participants valued the importance of building genuine, collaborative and deliberative relationships—underpinned by honesty, respect, co-learning and equity—and the impact of effective PE on research quality and relevance. Conclusions An explicit statement of values seeks to align all stakeholders on the purpose, practice and credibility of PE activities. An innovative, flexible and transparent research environment was valued as essential to developing a trustworthy evidence-base with which to underpin future guidance for good PE practice.Peer reviewe
Recommended from our members
Black carbon physical and optical properties across northern India during pre-monsoon and monsoon seasons
Black carbon (BC) is known to have major impacts on both climate and human health and is therefore of global importance, particularly in regions close to large populations that have strong sources. The size-resolved mixing state of BC-containing particles was characterised using a single-particle soot photometer (SP2). The study focusses on the Indo-Gangetic Plain (IGP) during the pre-monsoon and monsoon seasons. Data presented are from the UK Facility for Airborne Atmospheric Measurements BAe-146 research aircraft that performed flights during the pre-monsoon (11 and 12 June) and monsoon (30 June to 11 July) seasons of 2016.
Over the IGP, BC mass concentrations were greater (1.95 µg m−3) compared to north-west India (1.50 µg m−3) and north-east India (0.70 µg m−3) during the pre-monsoon season. Across northern India, two distinct BC modes were recorded; a mode of small BC particles (core diameter <0.16 µm and coating thickness <50 nm) and a mode of moderately coated BC (core diameter <0.22 µm and coating thickness of 50–200 nm). The IGP and north-east India locations exhibited moderately coated black carbon particles with enhanced coating thicknesses, core sizes, mass absorption cross sections, and scattering enhancement values compared to much lower values present in the north-west. The coating thickness and mass absorption cross section increased with altitude (13 %) compared to those in the boundary layer. As the monsoon arrived across the region, mass concentration of BC decreased over the central IGP and north-east locations (38 % and 28 % respectively), whereas for the north-west location BC properties remained relatively consistent. Post-monsoon onset, the coating thickness, core size, mass absorption cross section, and scattering enhancement values were all greatest over the central IGP much like the pre-monsoon season but were considerably reduced over both north-east and north-west India. Increases in mass absorption cross section through the atmospheric column were still present during the monsoon for the north-west and central IGP locations, but less so over the north-east due to lack of long-range transport aerosol aloft. Across the Indo-Gangetic Plain and north-east India during the pre-monsoon and monsoon seasons, solid-fuel (wood burning) emissions form the greatest proportion of BC with moderately coated particles. However, as the monsoon develops in the north-east there was a switch to small uncoated BC particles indicative of traffic emissions, but the solid-fuel emissions remained in the IGP into the monsoon. For both seasons in the north-west, traffic emissions form the greatest proportion of BC particles.
Our findings will prove important for greater understanding of the BC physical and optical properties, with important consequences for the atmospheric radiative forcing of BC-containing particles. The findings will also help constrain the regional aerosol models for a variety of applications such as space-based remote sensing, chemistry transport modelling, air quality, and BC source and emission inventories
Evaluation of children's centres in England: strand 2 - baseline survey of families using children's centres in the most disadvantaged areas
This is the final version of the report. Available from the Department for Education via the link in this recorThe evaluation of children’s centres in England is a large scale, six year study that looks at Sure Start children’s centres (SSCCs) in the most disadvantaged areas of England. These are centres that were set up in the first two phases of the programme.
The evaluation, from a survey of families who were using children’s centres when their child was 9- to 18-months-old, will provide a very detailed picture of children’s centre services. This includes how effective they are when they use different approaches in their management and when delivering services and activities for parents and children. It also looks at the cost of delivering different types of services
Assessing health-related quality of life (HRQoL) in survivors of out-of-hospital cardiac arrest : A systematic review of patient-reported outcome measures
Aim: High quality evidence of out-of-hospital cardiac arrest (OHCA) survivors' health-related quality of life (HRQoL) can measure the long-term impact of CA. The aim of this study was to critically appraise the evidence of psychometric quality and acceptability of measures used in the assessment of HRQoL in cardiac arrest survivors. Methods: Systematic literature searches (2004-2017) and named author searches to identify articles pertaining to the measurement of HRQoL. Data on study quality, measurement and practical properties were extracted and assessed against international standards. Results: From 356 reviewed abstracts, 69 articles were assessed in full. 25 provided evidence for 10 measures of HRQoL: one condition-specific; three generic profile measures; two generic index; and four utility measures. Although limited, evidence for measurement validity was strongest for the HUI3 and SF-36. However, evidence for reliability, content validity, responsiveness and interpretability and acceptability was generally limited or not available in the CA population for all measures. Conclusions: This review has demonstrated that a measure of quality of life specific to OHCA survivors is not available. Limited evidence of validity exists for one utility measure - the HUI3 - and a generic profile - the SF-36. Robust evidence of the quality and acceptability of HRQoL measures in OHCA was limited or not available. Future collaborative research must seek to urgently establish the relevance and acceptability of these measures to OHCA survivors, to establish robust evidence of essential measurement and practical properties over the short and long-term, and to inform future HRQoL assessment in the OHCA population. (C) 2017 Elsevier B.V. All rights reserved.Peer reviewe
Interpersonal touch interventions for patients in intensive care: A design-oriented realist review
Aim: To develop a theoretical framework to inform the design of interpersonal touch interventions intended to reduce stress in adult intensive care unit patients.
Design: Realist review with an intervention design‐oriented approach.
Methods: We searched CINAHL, MEDLINE, EMBASE, CENTRAL, Web of Science and grey literature sources without date restrictions. Subject experts suggested additional articles. Evidence synthesis drew on diverse sources of literature and was conducted iteratively with theory testing. We consulted stakeholders to focus the review. We performed systematic searches to corroborate our developing theoretical framework.
Results: We present a theoretical framework based around six intervention construction principles. Theory testing provided some evidence in favour of treatment repetition, dynamic over static touch and lightening sedation. A lack of empirical evidence was identified for construction principles relating to intensity and positive/negative evaluation of emotional experience, moderate pressure touch for sedated patients and intervention delivery by relatives versus healthcare practitioners
Spatial ecology of loggerhead turtles: Insights from stable isotope markers and satellite telemetry
This is the final version. Available on open access from Wiley via the DOI in this recordAim
Using a combination of satellite telemetry and stable isotope analysis (SIA), our aim was to identify foraging grounds of loggerhead turtles (Caretta caretta) at important rookeries in the Mediterranean, examine foraging ground fidelity, and across 25 years determine the proportion of nesting females recruiting from each foraging region to a major rookery in Cyprus.
Location
Mediterranean Sea.
Methods
Between 1993 and 2018, we investigated the spatial ecology of loggerhead turtles from rookeries in Cyprus and Greece using satellite telemetry (n = 55 adults) and SIA of three elements (n = 296).
Results
Satellite telemetry from both rookeries revealed the main foraging areas as the Adriatic region (Cyprus: 4% of individuals, Greece: 55%), Tunisian Plateau (Cyprus: 16%, Greece: 40%) and the eastern Mediterranean (Cyprus: 80%, Greece: 5%). Combining satellite telemetry and SIA allowed 64% of all nesting females to be assigned to; the Adriatic region (Cyprus: 2%, Greece: 38.5%), Tunisian Plateau (Cyprus: 47%, Greece: 38.5%) and the eastern Mediterranean (Cyprus: 51%, Greece: 23%), which are markedly different to proportions obtained using satellite telemetry. The proportion of the Cyprus nesting cohort using each foraging region did not change significantly, with the exception that individuals foraging in the Adriatic region are only present in the Cyprus nesting population from 2012. Repeat satellite tracking (n = 3) and temporal consistency in isotope ratios (n = 36) of Cyprus females, strongly suggest foraging ground fidelity over multiple decades.
Main conclusions
This study demonstrates the advantages of combining satellite telemetry and SIA to investigate spatial ecology at a population level. The importance of the Tunisian Plateau for foraging is demonstrated. This study indicates that females generally show high fidelity to foraging grounds and shows a potential recent shift to foraging in the Adriatic region for Cyprus females, while the importance of other regions persists across decades, thus providing baselines to develop and assess conservation strategies.Natural Environment Research Council (NERC
- …