EnTraP: A factorial randomised controlled trial embedded within world hip trauma evaluation eight COPAL investigating the effect of an enhanced trainee principal investigator package and digital nudge on recruitment rates

Background Randomised controlled trials (RCTs) often struggle with various aspects of participant recruitment, including engaging clinicians to recruit effectively, and subsequently fail to reach their target sample size. Studies evaluating interventions to improve recruitment aimed specifically at recruiters to the trial are limited in number. The RCTs embedded into the World Hip Trauma Evaluation (WHiTE) cohort study use Trainee Principal Investigators (TPIs) to help manage and drive recruitment at trial sites. No formalised training or support is provided by central trials units to the TPIs. Additionally, trial recruiters receive a generic automated email confirming randomisation to the trial with no other communication to influence or incentivise their behaviour to further recruit. The primary aim of this factorial trial was to evaluate the effectiveness of an educational intervention to TPIs and a positive reinforcement intervention via an email (digital) nudge on increasing recruitment. Secondary aims included feasibility of implementing the interventions and surveying TPIs on the educational package quality of content, delivery and ongoing support. Design This was a multicentre, open, cluster, 2x2 factorial RCT embedded in the WHiTE 8 COPAL RCT, in which research sites were randomised 1:1:1:1 to receive the enhanced TPI package, the digital nudge intervention, both, or neither. Results 1215 patients were recruited to the WHiTE 8 COPAL trial across 20 sites during the SWAT between August 2018 and March 2019. There was a statistically significant interaction between the interventions (IRR 2.09, 95% CI 1.64 to 2.68, p < 0.001). There was a statistically significant benefit on recruitment (IRR 1.23 95% 1.09 to 1.40, p=0.001) from utilizing an enhanced TPI education intervention. The digital nudge intervention had no significant impact on recruitment (IRR 0.89 95% CI 0.79 to 1.01, p=0.07). Within enhanced TPI package sites, the digital nudge had a beneficial effect, while in the standard practice TPI sites it had a detrimental effect. Feasibility analysis showed the median time to site digital nudge and enhanced TPI set up were one day and 17 days, respectively. 353 digital nudges were created taking an average of 12 min to construct, log the activity and then disseminate to recruiters. Median induction time for enhanced TPI was 32 min and 100% of the groups were extremely satisfied with the induction content, delivery and ongoing support. Discussion An education and support programme targeted at surgical TPIs involving a digital education package, 1:1 telephone induction and subsequent support package was effective in increasing recruitment in the first 6 months of trial commencement. There was no evidence for the effectiveness of the digital nudge intervention in isolation, although our results show that when combined with an education programme, it leads to enhanced effectiveness of that programme.

A Stringent Test of Magnetic Models of Stellar Evolution

Main-sequence stars with convective envelopes often appear larger and cooler than predicted by standard models of stellar evolution for their measured masses. This is believed to be caused by stellar activity. In a recent study, accurate measurements were published for the K-type components of the 1.62-day detached eclipsing binary EPIC 219511354, showing the radii and temperatures for both stars to be affected by these discrepancies. This is a rare example of a system in which the age and chemical composition are known, by virtue of being a member of the well-studied open cluster Ruprecht 147 (age~3 Gyr, [Fe/H] = +0.10). Here, we report a detailed study of this system with nonstandard models incorporating magnetic inhibition of convection. We show that these calculations are able to reproduce the observations largely within their uncertainties, providing robust estimates of the strength of the magnetic fields on both stars: 1600 ± 130 G and 1830 ± 150 G for the primary and secondary, respectively. Empirical estimates of the magnetic field strengths based on the measured X-ray luminosity of the system are roughly consistent with these predictions, supporting this mechanism as a possible explanation for the radius and temperature discrepancies.

SPECTROSCOPIC INVESTIGATIONS OF GALACTIC OPEN CLUSTER COLLINDER 394 – NEW RESULTS

Confident main-sequence (MS) members of the Collinder 394 open cluster are perfect objects to check the correctness of their distances, obtained from the GAIA GR2 (2018) catalogue. The differences in the distances to the open cluster Collinder 394, determined by photometry and from the GAIA parallaxes have raised doubts about the correctness of the latter. Therefore we used spectroscopically determined T eff and loggvalues for these stars from Usenko et al. (2019) and tried to solve the inverse problem: determine radii of these stars using the derived distances and calibrations “T eff - radius” for MS stars and compare with similar ones. For this purpose we used the calibrations from Torres et al. (2010), based on the nearest MS eclipsing binaries and compilations for MS stars from Mamajek (2018). As a result, we obtained relationships that connect T eff , logg, radii, masses, and distances for the confident Collinder 394 MS stars. We have confirmed the correctness of the GAIA DR2 (2018) distances for these stars and determined their radii and masses. The latter estimates turned out to be close to those of the evolutionary masses calculated by the PARSEC model

Membership Lists for 431 Open Clusters in Gaia DR2 Using Extreme Deconvolution Gaussian Mixture Models

Open clusters are groups of stars that form at the same time, making them an ideal laboratory to test theories of star formation, stellar evolution, and dynamics in the Milky Way disk. However, the utility of an open cluster can be limited by the accuracy and completeness of its known members. Here, we employ a “top-down” technique, Extreme Deconvolution Gaussian Mixture Models (XDGMMs), to extract and evaluate known open clusters from Gaia DR2 by fitting the distribution of stellar parallax and proper motion along a line of sight. Extreme deconvolution techniques can recover the intrinsic distribution of astrometric quantities, accounting for the full covariance matrix of the errors; this allows open cluster members to be identified even when presented with relatively uncertain measurement data. To date, open cluster studies have only applied extreme deconvolution to specialized searches for individual systems. We use XDGMMs to characterize the open clusters reported by Ahumada & Lapasset and are able to recover 420 of the 426 open clusters therein (98.1%). Our membership list contains the overwhelming majority (>95%) of previously known cluster members. We also identify a new, significant, and relatively faint cluster member population and validate their membership status using Gaia eDR3. We report the fortuitous discovery of 11 new open cluster candidates within the lines of sight we analyzed. We present our technique, as well as its advantages and challenges, and publish our membership lists and updated cluster parameters.

NGC 1605a and NGC 1605b: An Old Binary Open Cluster in the Galaxy

This work communicates the discovery of a binary open cluster within the Galaxy. NGC 1605 presents an unusual morphology with a sparse stellar distribution and a double core in close angular proximity. The 2MASS and Gaia-EDR3 field-star decontaminated color–magnitude diagrams (CMDs) show two distinct stellar populations located at the same heliocentric distance of ∼2.6 kpc, suggesting that there are two clusters in the region, NGC 1605a and NGC 1605b, with ages of 2 Gyr and 600 Myr, respectively. Both Gaia parallax and PM distributions are compact and very similar indicating that they are open clusters (OCs) and share the same kinematics. The large age difference, 1.4 Gyr, point to a formation by tidal capture during a close encounter and the close spatial proximity and similar kinematics suggest an ongoing merger event. There is some prominent tidal debris that appears to trace the cluster's orbits during the close encounter and, unexpectedly, some of them appear to be bound structures; this may suggest that in addition to the evaporation, the merging clusters are being broken apart into smaller structures by the combination of the Galactic disk, the Perseus arm, and mutual tidal interactions. In this sense, the newly found binary cluster may be a key object in the observational validation of theoretical studies on binary cluster pairs formation by tidal capture as well as in the formation of massive clusters by merging, and tidal disruption of stellar systems.

Orbital Parameters and Binary Properties of 37 FGK Stars in the Cores of Open Clusters NGC 2516 and NGC 2422

We present orbits for 24 binaries in the field of open cluster NGC 2516 (∼150 Myr) and 13 binaries in the field of open cluster NGC 2422 (∼130 Myr) using results from a multiyear radial-velocity (RV) survey of the cluster cores. Six of these systems are double-lined spectroscopic binaries. We fit these RV variable systems with orvara, a MCMC-based fitting program that models Keplerian orbits. We use precise stellar parallaxes and proper motions from Gaia EDR3 to determine cluster membership. We impose a barycentric RV prior on all cluster members; this significantly improves our orbital constraints. Two of our systems have periods between five and 15 days, the critical window in which tides efficiently damp orbital eccentricity. These binaries should be included in future analyses of circularization across similarly-aged clusters. We also find a relatively flat distribution of binary mass ratios, consistent with previous work. With the inclusion of TESS light curves for all available targets, we identity target 378–036252 as a new eclipsing binary. We also identify a field star whose secondary has a mass in the brown dwarf range, as well as two cluster members whose RVs suggest the presence of an additional companion. Our orbital fits will help constrain the binary fraction and binary properties across stellar age and across stellar environment.

Globular Cluster Candidates in the Sagittarius Dwarf Galaxy

Recently, new Sagittarius (Sgr) dwarf-galaxy globular clusters were discovered, which opens the question of the actual size of the Sgr globular cluster population, and therefore on our understanding of the Sgr galaxy formation and accretion history of the Milky Way. Based on Gaia EDR3 and SDSS IV DR16 (APOGEE-2) data sets, we performed an analysis of the color–magnitude diagrams (CMDs) of the eight new Sgr globular clusters found by Minniti et al. from a sound cleaning of the contamination of Milky Way and Sgr field stars, complemented by available kinematic and metal abundance information. The cleaned CMDs and spatial stellar distibutions reveal the presence of stars with a wide range of cluster membership probabilities. Minni 332 turned out to be a younger (<9 Gyr) and more metal-rich ([M/H] ≳ −1.0 dex) globular cluster than M54, the nuclear Sgr globular cluster; as could also be the case of Minni 342, 348, and 349, although their results are less convincing. Minni 341 could be an open cluster candidate (age < 1 Gyr, [M/H] ∼ −0.3 dex), while the analyses of Minni 335, 343, and 344 did not allow us to confirm their physical reality. We also built the Sgr cluster frequency (CF) using available ages of the Sgr globular clusters and compared it with that obtained from the Sgr star formation history. Both CFs are in excellent agreement. However, the addition of eight new globular clusters with ages and metallicities distributed according to the Sgr age–metallicity relationship turns out in a remarkably different CF.

Astrometric Observations of a Near-Earth Object Using the Image Fusion Technique

The precise astrometric observation of small near-Earth objects (NEOs) is an important observational research topic in the astrometric discipline, which greatly promotes multidisciplinary research, such as the origin and evolution of the solar system, the detection and early warning of small NEOs, and deep-space navigation. The characteristics of small NEOs, such as faintness and fast moving speed, restrict the accuracy and precision of their astrometric observations. In the paper, we present a method to improve the accurate and precise astrometric positions of NEOs based on image fusion technique. The noise analysis and astrometric test from the observed images of the open cluster M23 are given. Using the image fusion technique, we obtain the sets of superimposed images and original images containing reference stars and moving targets, respectively. The final fused image set includes background stars with high signal-to-noise ratios and ideal NEO images simultaneously and avoids the saturation of background stars. Using the fused images, we can reduce the influence of telescope tracking and NEO ephemeris errors on astrometric observations, and our results indicate that the accuracy and precision of NEO Eros astrometry are improved obviously after we choose suitable image fuse mode.

Sensitivity of Some Sweet Cherry (Prunus Avium L.) Genotypes To Late Spring Frosts During Different Phenological Stages Following Bud Burst

Sweet cherry (Prunus avium L.) is one of the economically important fruit crops worldwide. However, late spring frosts occurring in some years can significantly impact sweet cherry productivity through organ and tissue destruction caused by frost damage, and very little is known about frost tolerance or susceptibility of new cultivars. Differential thermal analysis (DTA) was, therefore, used to examine the exothermic characteristics (temperatures at which 50% of the flower buds were killed - mLTE values) of the flower buds belonging to members of the genus Prunus - 6 Prunus avium cultivars ('Noir de Guben', 'Bigarreau Gaucher', 'Merton Late', 'Merton Bigarreau', 'Van' and wild genotype). In the study, mLTE values of flowers of six cherry cultivars were determined at different floral bud developmental stages such as side green, green tip, open cluster, first white and full bloom under laboratory-based freeze assays for consecutive two years. The mLTE values of flower buds changed according to both different floral bud developmental stages and sweet cherry cultivars. In our findings, the mLTE values of flower buds in all cultivars generally occurred at higher temperatures in the open cluster stage, whereas the mLTE values of the flower buds in the first white stage occurred at lower temperatures, and therefore, these results are not only controversial in terms of previous frost tolerance studies, but also the first findings to be reported in literature. Considering the two-year average, the temperatures causing mLTE values for flower buds was -1.58 to -3.74°C at the side green stage, -0.94 to -3.51°C at the green tip stage, -0.41 to -1.96°C at the open cluster stage, -2.30 to -11.52°C at the first white stage and -2.37 to -9.80°C at the full bloom stage in the range of six cultivars. In laboratory-based freezing experiments, the 'Van' cultivar were least affected by low temperatures, followed by 'Bigarreau Gaucher' cultivar and wild genotype. 'Merton Late' cultivar, on the contrary, was the most sensitive cultivar to low temperatures, followed by 'Noir de Guben' and 'Merton Bigarreau'. These results can be valuable in predicting possible frost damage at different developmental stages of the flower buds in sweet cherry.