869 research outputs found
Detecting the Companions and Ellipsoidal Variations of RS CVn Primaries: I. sigma Geminorum
To measure the properties of both components of the RS CVn binary sigma
Geminorum (sigma Gem), we directly detect the faint companion, measure the
orbit, obtain model-independent masses and evolutionary histories, detect
ellipsoidal variations of the primary caused by the gravity of the companion,
and measure gravity darkening. We detect the companion with interferometric
observations obtained with the Michigan InfraRed Combiner (MIRC) at Georgia
State University's Center for High Angular Resolution Astronomy (CHARA) Array
with a primary-to-secondary H-band flux ratio of 270+/-70. A radial velocity
curve of the companion was obtained with spectra from the Tillinghast Reflector
Echelle Spectrograph (TRES) on the 1.5-m Tillinghast Reflector at Fred Lawrence
Whipple Observatory (FLWO). We additionally use new observations from the
Tennessee State University Automated Spectroscopic and Photometric Telescopes
(AST and APT, respectively). From our orbit, we determine model-independent
masses of the components (M_1 = 1.28 +/- 0.07 M_Sun, M_2 = 0.73 +/- 0.03
M_Sun), and estimate a system age of 5 -/+ 1 Gyr. An average of the 27-year APT
light curve of sigma Gem folded over the orbital period (P = 19.6027 +/- 0.0005
days) reveals a quasi-sinusoidal signature, which has previously been
attributed to active longitudes 180 deg apart on the surface of sigma Gem. With
the component masses, diameters, and orbit, we find that the predicted light
curve for ellipsoidal variations due to the primary star partially filling its
Roche lobe potential matches well with the observed average light curve,
offering a compelling alternative explanation to the active longitudes
hypothesis. Measuring gravity darkening from the light curve gives beta < 0.1,
a value slightly lower than that expected from recent theory.Comment: Accepted to ApJ, 11 pages, 6 figures, 8 table
Attending to design when developing complex health interventions: A qualitative interview study with intervention developers and associated stakeholders
Background Guidance and frameworks exist to assist those developing health interventions but may offer limited discussion of ‘design’, the part of development concerned with generating ideas for and making decisions about an intervention’s content, format and delivery. The aim of this paper is to describe and understand the views and experiences of developers and associated stakeholders in relation to how design occurs in health intervention development. Methods Semi-structured interviews were conducted with 21 people who had developed complex interventions to improve health and/or who were relevant stakeholders (e.g. funders and publishers of intervention development work), regarding their views, experiences and approaches to intervention design. Sampling was purposive in terms of maximising diversity. A thematic inductive analysis was conducted. Results Approaches to design varied substantially between intervention developers. This contrasted with consistency in other activities undertaken during development, such as literature review. Design also posed more challenges than other parts of development. We identified six ‘modes’ of design: informed; negotiated; structured; delegated; ‘my baby’; and creative partnership. In understanding the differences between these different modes, and the challenges posed by intervention design, we identified three key themes: enabling creativity during the design process; working with different types of knowledge; and ‘stabilising’ (developing clear shared understandings of) the intervention development to enable design. Conclusions Design has received less attention than other activities undertaken when developing interventions to improve health. Developers take a variety of approaches to design and often find it challenging. Guidance for intervention development in health has tended to see design as proceeding in a predictable and controlled manner from acquired knowledge. Our study suggests that design rarely reflects this rational ideal. Future guidance on intervention development in healthcare should support developers to work effectively with different types of knowledge, to help design progress more smoothly and to maximise creativity
Organizational theory for dissemination and implementation research
Abstract Background Even under optimal internal organizational conditions, implementation can be undermined by changes in organizations’ external environments, such as fluctuations in funding, adjustments in contracting practices, new technology, new legislation, changes in clinical practice guidelines and recommendations, or other environmental shifts. Internal organizational conditions are increasingly reflected in implementation frameworks, but nuanced explanations of how organizations’ external environments influence implementation success are lacking in implementation research. Organizational theories offer implementation researchers a host of existing, highly relevant, and heretofore largely untapped explanations of the complex interaction between organizations and their environment. In this paper, we demonstrate the utility of organizational theories for implementation research. Discussion We applied four well-known organizational theories (institutional theory, transaction cost economics, contingency theories, and resource dependency theory) to published descriptions of efforts to implement SafeCare, an evidence-based practice for preventing child abuse and neglect. Transaction cost economics theory explained how frequent, uncertain processes for contracting for SafeCare may have generated inefficiencies and thus compromised implementation among private child welfare organizations. Institutional theory explained how child welfare systems may have been motivated to implement SafeCare because doing so aligned with expectations of key stakeholders within child welfare systems’ professional communities. Contingency theories explained how efforts such as interagency collaborative teams promoted SafeCare implementation by facilitating adaptation to child welfare agencies’ internal and external contexts. Resource dependency theory (RDT) explained how interagency relationships, supported by contracts, memoranda of understanding, and negotiations, facilitated SafeCare implementation by balancing autonomy and dependence on funding agencies and SafeCare developers. Summary In addition to the retrospective application of organizational theories demonstrated above, we advocate for the proactive use of organizational theories to design implementation research. For example, implementation strategies should be selected to minimize transaction costs, promote and maintain congruence between organizations’ dynamic internal and external contexts over time, and simultaneously attend to organizations’ financial needs while preserving their autonomy. We describe implications of applying organizational theory in implementation research for implementation strategies, the evaluation of implementation efforts, measurement, research design, theory, and practice. We also offer guidance to implementation researchers for applying organizational theory
NGTS-28Ab:a short period transiting brown dwarf
We report the discovery of a brown dwarf orbiting a M1 host star. We first identified the brown dwarf within the Next Generation Transit Survey data, with supporting observations found in TESS sectors 11 and 38. We confirmed the discovery with follow-up photometry from the South African Astronomical Observatory, SPECULOOS-S, and TRAPPIST-S, and radial velocity measurements from HARPS, which allowed us to characterize the system. We find an orbital period of ∼1.25 d, a mass of 69.0+5.3-4.8 MJ, close to the hydrogen burning limit, and a radius of 0.95 ± 0.05 RJ. We determine the age to be >0.5 Gyr, using model isochrones, which is found to be in agreement with spectral energy distribution fitting within errors. NGTS-28Ab is one of the shortest period systems found within the brown dwarf desert, as well as one of the highest mass brown dwarfs that transits an M dwarf. This makes NGTS-28Ab another important discovery within this scarcely populated region.</div
Spirometric phenotypes from early childhood to young adulthood : a Chronic Airway Disease Early Stratification study
Acknowledgements Cohort-specific acknowledgements are presented in the supplementary material. We also acknowledge collaboration with the EXPANSE consortium (funded by the EU H2020 programme, grant number 874627). We thank Elise Heuvelin, European Respiratory Society, Lausanne, Switzerland, for her assistance on the current project.Peer reviewedPublisher PD
Outcomes for Implementation Research: Conceptual Distinctions, Measurement Challenges, and Research Agenda
An unresolved issue in the field of implementation research is how to conceptualize and evaluate successful implementation. This paper advances the concept of “implementation outcomes” distinct from service system and clinical treatment outcomes. This paper proposes a heuristic, working “taxonomy” of eight conceptually distinct implementation outcomes—acceptability, adoption, appropriateness, feasibility, fidelity, implementation cost, penetration, and sustainability—along with their nominal definitions. We propose a two-pronged agenda for research on implementation outcomes. Conceptualizing and measuring implementation outcomes will advance understanding of implementation processes, enhance efficiency in implementation research, and pave the way for studies of the comparative effectiveness of implementation strategies
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RAISE study protocol: a cross-sectional, multilevel, neurobiological study of resilience after individual stress exposure
Introduction: This paper describes the protocol for an ongoing project funded by the Royal Society, the Resilience After Individual Stress Exposure (RAISE) study; which aims to examine the factors and mechanisms that facilitate resilient functioning after childhood adversity (CA). Methods and analysis: We aim to recruit up to 200 participants. We will use dimension reduction techniques (principal component analysis) on standard-normally transformed individual parameters of mental health, social functioning and CA to calculate a composite measure of adaptive (ie, ‘resilient’) psychosocial functioning. To examine the neuroimmune responses to stress and their relationship with the brain and social environment, we will use a well validated functional MRI task; the Montreal imaging stress task and venepuncture. We will run group or dimensional comparisons in multiple levels of biological and psychological outcomes, as well as mediation and moderation analyses to study how key biological systems (ie, the hypothalamic–pituitary–adrenal axis and the immune system) interrelate and interact with brain function and social influences in order to facilitate resilient functioning after CA. We hypothesise that resilient functioning will be facilitated by reduced morning cortisol and cytokine levels before and after the stressor and improved neural responses to such stress, as well as increased gray matter volume in the hippocampus and prefrontal cortex, enhanced inhibitory control and emotion regulation, and more friendship and family support. Ethics and dissemination: This study has been reviewed and given favourable opinion by the National Research Ethics Service, NRES Committee East of England-Cambridge Central and external reviewers from the Royal Society (RGF\R1\180064 and RGF\EA\180029). The results of the RAISE study will be disseminated through (1) publications in scientific peer reviewed journals, (2) presentations on relevant scientific conferences and meetings, (3) publications and presentations for the general public and (4) through social media
Vitamin D levels in children and adolescents with chronic tic disorders: a multicentre study
This study investigated whether vitamin D is associated with the presence or severity of chronic tic disorders and their psychiatric comorbidities. This cross-sectional study compared serum 25-hydroxyvitamin D [25(OH)D] (ng/ml) levels among three groups: children and adolescents (3-16 years) with CTD (n = 327); first-degree relatives (3-10 years) of individuals with CTD who were assessed for a period of up to 7 years for possible onset of tics and developed tics within this period (n = 31); and first-degree relatives who did not develop tics and were ≥ 10 years old at their last assessment (n = 93). The relationship between 25(OH)D and the presence and severity of tics, as well as comorbid obsessive-compulsive disorder (OCD) and attention-deficit/hyperactivity disorder (ADHD), were analysed controlling for age, sex, season, centre, latitude, family relatedness, and comorbidities. When comparing the CTD cohort to the unaffected cohort, the observed result was contrary to the one expected: a 10 ng/ml increase in 25(OH)D was associated with higher odds of having CTD (OR 2.08, 95% CI 1.27-3.42, p < 0.01). There was no association between 25(OH)D and tic severity. However, a 10 ng/ml increase in 25(OH)D was associated with lower odds of having comorbid ADHD within the CTD cohort (OR 0.55, 95% CI 0.36-0.84, p = 0.01) and was inversely associated with ADHD symptom severity (β = - 2.52, 95% CI - 4.16-0.88, p < 0.01). In conclusion, lower vitamin D levels were not associated with a higher presence or severity of tics but were associated with the presence and severity of comorbid ADHD in children and adolescents with CTD
The First Post-Kepler Brightness Dips of KIC 8462852
We present a photometric detection of the first brightness dips of the unique variable star KIC 8462852 since the end of the Kepler space mission in 2013 May. Our regular photometric surveillance started in October 2015, and a sequence of dipping began in 2017 May continuing on through the end of 2017, when the star was no longer visible from Earth. We distinguish four main 1-2.5% dips, named "Elsie," "Celeste," "Skara Brae," and "Angkor", which persist on timescales from several days to weeks. Our main results so far are: (i) there are no apparent changes of the stellar spectrum or polarization during the dips; (ii) the multiband photometry of the dips shows differential reddening favoring non-grey extinction. Therefore, our data are inconsistent with dip models that invoke optically thick material, but rather they are in-line with predictions for an occulter consisting primarily of ordinary dust, where much of the material must be optically thin with a size scale <<1um, and may also be consistent with models invoking variations intrinsic to the stellar photosphere. Notably, our data do not place constraints on the color of the longer-term "secular" dimming, which may be caused by independent processes, or probe different regimes of a single process
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