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How to design an effective membership probability is an important component for Gaussian mixture model (GMM) of point set registration. In order to improve the robustness of point set registration, in this paper, a new representation is proposed for membership probability of Gaussian mixture model, by utilizing two types of feature descriptor, i.e. shape context or fast point feature histograms. Moreover, for each point of the model point set, a dynamic programming (DP) algorithm is developed to search for the optimal candidate points from the target point set. Compared to the state-of-the-art approaches, the proposed approach is more robust to deformation, outlier, occlusion, and rotation. Experimental results on several widely used 2D and 3D data demonstrate the effectiveness and feasibility of the proposed algorithm.

We report the discovery of VMC J021140.41-735320.4, a faint ($J=19.9$ mag) and extremely red ($J-K_s=3.0$ mag, $W1-W2=0.45$ mag, $J-W2=4.7$ mag) high proper motion object in front of the Magellanic Bridge region. It is even redder in the near-infrared than the reddest L7 dwarfs ($J-K_s \gtrsim 2.8$ mag) found in the survey of Schneider et al. (2017) and its colours do also not match exactly those of other peculiar red L7.5 dwarfs. Therefore, we consider its photometric distance estimate of about 73 pc as uncertain. A preliminary combined proper motion and parallax solution involving 20 epochs from the Visible and Infrared Survey Telescope for Astronomy (VISTA) survey of the Magellanic Clouds (VMC), the VISTA hemisphere survey (VHS), and the Wide-field Infrared Survey Explorer (WISE) yields $\mu_{\alpha}\cos{\delta}=+74.3\pm3.4$ mas/yr, $\mu_{\delta}=+22.3\pm3.4$ mas/yr, and $\pi=21.0\pm7.1$ mas. Applying the BANYAN tool (http://www.exoplanetes.umontreal.ca/banyan/) to these results we find a $\approx$68% membership probability of this object in the AB Doradus young moving group (YMG). With its trignometric distance of $\approx$48 pc, VMC J021140.41-735320.4 has a similar absolute magnitude of $M_{K_s}\approx13.4$ mag as the planetary mass companion of another AB Doradus YMG member candidate, 2MASS J22362452+4751425. Follow-up classification spectroscopy and astrometric monitoring are recommended., Comment: 2 pages, 1 figure, published in RNAAS (abstract not included in original paper)

We analyze the membership probability of young stars belonging to nearby moving groups with $\textit{Gaia}$ DR2 data. The sample of 1429 stars were identified from 'The Catalog of Suspected Nearby Young Moving Group Stars'. Good-quality parallax and proper motion values were retrieved for 890 stars from $\textit{Gaia}$ DR2 database. The analysis for membership probability is performed in the framework of LACEwING algorithm. From the analysis it is confirmed that 279 stars do not belong to any of the known moving groups. We estimated the $\textit{ U, V, W}$ space velocity values for 250 moving group members, which were found to be more accurate than previous values listed in the literature. The velocity ellipses of all the moving groups are well constrained within the "good box", a widely used criterion to identify moving group members. The age of moving group members are uniformly estimated from the analysis of $\textit{Gaia}$ Color-Magnitude Diagram with MIST isochrones. We found a spread in the age distribution of stars belonging to some moving groups, which needs to be understood from further studies., Comment: 14 Pages, 5 Figures, 4 Tables, Accepted for publication in AJ

We present results of a UBVIC variability survey in the young open cluster NGC 2244. In total, we found 245 variable stars. Most of them, 211 stars, are variables with irregular variations. Furthermore, 23 periodic variables were found. We also detected four candidates for δ Scuti stars and seven eclipsing binaries. Based on the mid-infrared Spitzer and WISE photometry and near infrared JHKS 2MASS photometry, we classified 104 young stellar sources among our variables: 1 Class I object, 1 Class I/flat spectrum object, 4 flat spectrum objects, 91 Class II objects, and 7 transition disc objects. This classification, together with r′i′Hα IPHAS photometry and JHK UKIDSS photometry, were used for identification of pre-main sequence stars among irregular and periodic variables. In this way, 97 CTTS candidates (96 irregular and one periodic variable), 68 WTTS candidates (54 irregular and 14 periodic variables), and 6 Herbig Ae/Be stars were found. For 223 variable stars we calculated membership probability based on proper motions from Gaia DR2 catalogue. Majority of them, 143 stars, are cluster members with probability greater than 70 per cent. For only 36 variable stars the membership probability is smaller than 20 per cent.

This study shows the application of a system to monitor the state of damage of railway wheel steel specimens during rolling contact fatigue tests. This system can make continuous measurements with an evaluation of damage without stopping the tests and without destructive measurements. Four tests were carried out to train the system by recording torque and vibration data. Both statistical and spectral features were extracted from the sensors signals. A Principal Component Analysis (PCA) was performed to reduce the volume of the initial dataset, then, the data were classified with the k-means algorithm. The results were then converted into probabilities curves. Metallurgical investigations (optical micrographs, wear curves) and hardness tests were carried out to assess the trends of machine learning analysis. The training tests were used to train the proposed algorithm. Three validation tests were performed by using the real-time results of the k-means algorithm as a stop condition. Metallurgical analysis was performed also in this case. The validation tests follow the results of the training test and metallurgical analysis confirms the damage found with the machine learning analysis: when the membership probability of the cluster corresponding to the damage state reaches a value higher than 0.5, the metallurgical analysis clearly shows the cracks on the surface of the specimen due to the rolling contact fatigue (RCF) damage mechanism. These preliminary results are positive, even if reproduced on a limited set of specimens. This approach could be integrated in rolling contact fatigue tests to provide additional information on damage progression.

We present a study of 7 southern open clusters based on UBVRI CCD photomety (Johnsons-Cousins system) and Gaia DR2 data. Dias 4, Dias 6 and four other clusters had UBVRI photometric observations determined for the first time. From the observational UBVRI data we obtained photometric membership probability estimates and, using the proper motions from the UCAC5 catalog, we also determined the kinematic membership. From Gaia DR2 astrometric data we determine the stellar membership using proper motions and parallaxes, taking into account the full covariance matrix. For both independent sets of data and membership we apply our non subjective multidimensional global optimization tool to fit theoretical isochrones to determine the distance, age, reddening, metallicity and binary fraction of the clusters. The results of the mean proper motions, distances and ages are in agreement, but the ones obtained from Gaia DR2 data are more precise in both membership selection and estimated parameters. In the case of NGC 6087, the Cepheid S Nor, member of the open cluster, was used to obtain an independent distance estimate, confirming the one determined by our fitting method. We also report a serendipitous discovery of two new clusters in the extended field near what was originally Dias 4., Accepted for publication in Monthly Notices of the Royal Astronomical Society

The association between life-course socio-professional trajectories and mortality has already been discussed in the literature. However, these socio-professional trajectories may be subject to informative censoring due to death. This loss to follow-up which is related to an individual’s survival, should not be ignored and thus, it is of interest to model jointly these professional trajectories and their survival. The main focus has been made on continuous, binary or ordinal variables while much less attention has been paid to nominal categorical data. Therefore, an extension to the joint modelling of longitudinal nominal data and survival under a likelihood-based approach is proposed. A generalized linear mixed model is considered for modelling the longitudinal nominal data, in addition to two cause-specific proportional hazards model for the survival competing risks data. The association between longitudinal and survival outcomes is captured by assuming a multivariate Gaussian distribution for the joint distribution of the random effects of two sub-models. The proposed joint model provides a robust framework for estimating longitudinal membership probabilities, accounting for informative censoring caused by individual’s death. Simulations are carried out to assess the performance of this joint model comparing with the results of the separate longitudinal and competing risks analysis. A disadvantage of joint models is that they are computationally intensive. To overcome this problem, an approach mimicking a meta-analysis strategy of individual participant data is suggested. The relevance of this approach is then illustrated on a large sample of the French salaried population, which contains all employment records between 1976 and 2002.

Nearby young moving groups provide unique samples of similar age stars for testing the evolution of physical properties. Incomplete and/or incorrect group membership classifications reduce the usefulness of the group, which we assume to be coeval. With near-infrared spectra of two candidate members of the TW Hya Association, 2MASS J12354615$-$4115531 (TWA 46) and 2MASS J12371238$-$4021480 (TWA 47), we test their membership by adding radial velocity measurements to the literature. We find that 2MASS J12354615$-$4115531 is a close spectroscopic binary system with a center-of-mass radial velocity of -6.5$\pm$3.9 km s$^{-1}$. This radial velocity and a $\textit{Gaia}$ parallax produces a TWA membership probability of 41.9$\%$ using the Banyan $\Sigma$ tool for 2MASS J12354615$-$4115531. The spectrum of 2MASS J12371238$-$4021480 shows that it appears to be a single star with a radial velocity consistent with the TW Hya Association and a membership probability of 99.5$\%$. The reduced probability of TWA 46 as a true member of TWA highlights the importance of high-resolution, near-infrared spectra in validating low-mass moving group members., Comment: 10 pages, 4 figures, 2 tables

Interstellar polarimetric data of the six open clusters Hogg 15, NGC 6611, NGC 5606, NGC 6231, NGC 5749 and NGC 6250 have been used to estimate the membership probability for the stars within them. For proper-motion member stars, the membership probability estimated using the polarimetric data is in good agreement with the proper-motion cluster membership probability. However, for proper-motion non-member stars, the membership probability estimated by the polarimetric method is in total disagreement with the proper-motion cluster membership probability. The inconsistencies in the determined memberships may be because of the fundamental differences between the two methods of determination: one is based on stellar proper-motion in space and the other is based on selective extinction of the stellar output by the asymmetric aligned dust grains present in the interstellar medium. The results and analysis suggest that the scatter of the Stokes vectors q(%) and u(%) for the proper-motion member stars depends on the interstellar and intra-cluster differential reddening in the open cluster. It is found that this method could be used to estimate the cluster membership probability if we have additional polarimetric and photometric information for a star to identify it as a probable member/non-member of a particular cluster, such as the maximum wavelength value (\lambda_max), the unit weight error of the fit (\sigma_1), the dispersion in the polarimetric position angles (\epsilon), reddening (E(B-V)) or the differential intra-cluster reddening (\Delta E(B-V)). This method could also be used to estimate the membership probability of known member stars having no membership probability as well as to resolve disagreements about membership among different proper-motion surveys., Comment: 11 pages, 3 figures, 5 tables, accepted for publication in MNRAS

Objective Common mental disorders are a major concern in working populations due to their high prevalence and as a barrier to remaining healthy and productive at work. Patients with common mental disorders often suffer from comorbidities, which may limit their functioning at work. We assessed the longitudinal impact of multimorbidity, defined as two or more co-occurring chronic health conditions, on work functioning among workers who had returned to work after sick leave due to a common mental disorder. Methods Prospective cohort study of 156 workers followed for one year after return to work from sick leave due to a common mental disorder. A multimorbidity score was computed by counting severity-weighted chronic health conditions measured at baseline. Work functioning was measured at baseline and at 3, 6 and 12 months follow-up with the Work Role Functioning Questionnaire. Work functioning trajectories were identified using latent class growth analysis to investigate the effect of multimorbidity on the course of work functioning scores. Results A total of 44% workers had multimorbidity. Four work functioning trajectories were identified: one (12% of the workers) showed increasing work functioning scores during follow-up, whereas the other three trajectories showed stable low, medium and high scores (23%, 41% and 25% workers, respectively). Multimorbidity did not predict membership probability in any trajectory. However, within the increasing score trajectory, levels of work functioning were lower among those with a high baseline multimorbidity score; each one unit increase in multimorbidity implied a reduction of 1.4 points in the work functioning score (p > 0.001). Conclusions Multimorbidity has a negative impact on workers’ perception of work functioning after returning to work from a sick leave due to a common mental disorder.

This paper investigates the spatial distribution of cattle breeders in Texas to quantify how climate factors influence cattle breed selection. A multivariate probit model is employed to examine the county-level binary choices of Bos taurus, Bos indicus and composite breeds derived from cattle breed association membership data. The estimation results suggest that summer heat stress is a significant factor for breed selection: positive for Bos indicus and negative for Bos taurus and composite breeds, with the average marginal effects on breed membership probability being 9.7 %, −26.5 % and −7.9 %, respectively. The intensity of the summer heat impacts can lead to noteworthy changes in spatial distributions of Texas cattle breeds in the event of climate change.

We present an analysis of the WISE photometric data for 829 stars in the Sco-Cen OB2 association, using the latest high-mass membership probabilities. We detect infrared excesses associated with 135 BAF-type stars, 99 of which are secure Sco-Cen members. There is a clear increase in excess fraction with membership probability, which can be fitted linearly. We infer that 41+-5% of Sco-Cen OB2 BAF stars to have excesses, while the field star excess fraction is consistent with zero. This is the first time that the probability of non-membership has been used in the calculation of excess fractions for young stars. We do not observe any significant change in excess fraction between the three subgroups. Within our sample, we have observed that B-type association members have a significantly smaller excess fraction than A and F-type association members.

We use new data from Gaia DR2 to confirm that the young L1 $\gamma$ candidate member of the TW Hya association (TWA) is now a bona fide member with a model-dependent mass estimate of ~15 $M_{Jup}$. The ambiguous M9 $\gamma$ candidate member 2MASS J12474428---3816464 also gets a higher Bayesian membership probability for TWA membership as a result of Gaia DR2 data and a new radial velocity measurement, but it remains unclear whether it is a true member of TWA or if it is an unrelated young interloper, because it is separated by 4.6 km/s from the locus of TWA members in UVW space.

The literature on the $\lambda$ Boo stars has grown to become somewhat heterogenous, as different authors have applied different criteria across the UV, optical and infrared regions to determine the membership status of $\lambda$ Boo candidates. We aim to clear up the confusion by consulting the literature on 212 objects that have been considered as $\lambda$ Boo candidates, and subsequently evaluating the evidence in favour of their admission to the $\lambda$ Boo class. We obtained new spectra of $\sim$90 of these candidates and classified them on the MK system to aid in the membership evaluations. The re-evaluation of the 212 objects resulted in 64 members and 103 non-members of the $\lambda$ Boo class, with a further 45 stars for which membership status is unclear. We suggest observations for each of the stars in the latter category that will allow them to be confidently included or rejected from the class. Our reclassification facilitates homogenous analysis on group members, and represents the largest collection of confirmed $\lambda$ Boo stars known., Comment: 40 pages, 2 tables (spanning 4 pages), 0 figures. Accepted for publication in PASA. (The MN style file was used for convenience in manuscript preparation, only.)

Using deep exposures (~10^5 s) with the ROSAT HRI, we have performed flux-limited surveys for X-ray sources in the vicinity of the Hyades-age open stellar clusters NGC 6633 and IC 4756, detecting 31 and 13 sources respectively. Our primary aim is to search for so-far unrecognised cluster members. We propose identifications or classifications (cluster member, field star, extragalactic field object) for the X-ray sources, based on published membership lists, and on X-ray:optical flux ratios and optical colour--magnitude diagrams. Results of simulating the expected X-ray-emitting source populations are compared with the ROSAT measurements and with the expected capabilities of the XMM mission. The simulations provide a novel method of comparing the activity levels of NGC 6633 and IC 4756 with that of the Hyades. The measurements and simulations confirm that cluster members are the major class of X-ray emitter in these fields at flux levels f_x > 10^{-14}/erg/cm^2/s (0.1--2.4 keV), contributing ~40 per cent of the total X-ray sources. We find 6 possible new members in NGC 6633, and 4 candidates in IC 4756; all require further observation to establish membership probability.

We present mean absolute proper motions of 112 open clusters, determined using the data from the Tycho2 Catalogue. For 28 clusters, this is the rst determination of proper motion. The measurements made use of a large number of stars (usually several tens) for each cluster. The total number of stars studied in the elds of the 164 open clusters is 5016, of which 4006 were considered members. The mean proper motions of the clusters and membership probability of individual stars were obtained from the proper motion data by applying the statistical method proposed by Sanders (1971).

87 stars in the NGC 6913 field with both UBV and Vilnius photometry are selected to be the sample. The membership probability of the stars is greater than 50%. The correlation among Vilnius photometry, UBV photometry and reddening in the cluster is reviewed. It is found that the photometry in the Vilnius X, Y and Z bands can be used to make rough spectral classification. The values of E( B-V ) are well correlated with the Vilnius colors of X-Y, Y-Z, Z-V and V-S in NGC 6913. The ratio of ( V-S )/( Y-Z ) of the MPCM (Most Possible Cluster Members) is a constant (1.30 ∼ p0.06), and has no effect on the values of E( B-V ), ( B-V ) 0 and V 0 . Comparing with the observational data of all the stars of NGC 6913 region, we propose that the value of ( V-S )/( Y-Z ) can probably be used to select the preliminary candidates of one open cluster. In addition, 12 variable stars are discovered in the NGC 6913 region, in which star #155 has a variation with an amplitude of 4.25 mag.

Open clusters become a powerful astrophysics laboratory once the essential problem of stellar membership has been solved. In this paper different methods to compute membership probabilities using kinematical variables, mainly proper motions, are presented.

This study examined the longitudinal link between clique membership status and the development of psychopathology in 451 children followed annually from age 9 to 12 years. Classroom clique membership status was identified through social network analysis, and internalizing and externalizing problems were assessed using peer nominations. Controlling for concurrent experiences of social preference and dyadic friendships, a high clique membership probability was found to be related to low levels of internalizing problems and to an increase in externalizing problems across 4 years. This link between clique membership and an increase in externalizing problems was found for boys only. © Taylor & Francis Group, LLC.

Astrometric cluster membership probabilities have been derived from proper motion of the open cluster NGC 2301. A comparison with previous investigations is presented.