Determinants Of Membership Research Articles

The Star Formation History of the Young Open Cluster NGC 2244: Study of the Binary Fraction

A star formation history (SFH) is the stellar record of the various processes that shaped a galaxy and star clusters since its birth to its current physical state. Studying the young open cluster NGC 2244, and in particular its massive stellar population, can improve our understanding of its formation mechanism, stellar evolution, feedback, and provide a basis for a better understanding of the formation of extragalactic star clusters. In this contribution, we present the first steps towards the derivation of the SFH of NGC 2244. We discuss the first results concerning the membership determination and the observed binary fractions of O- and B-type stars among NGC 2244. Finally, an overview of the forthcoming steps is also presented.

Using GMM in open cluster membership: An insight

The unprecedented precision of Gaia has led to a paradigm shift in membership determination of open clusters where a variety of machine learning (ML) models can be employed. In this paper, we apply the unsupervised Gaussian Mixture Model (GMM) to a sample of thirteen clusters with varying ages (logt≈ 6.38-9.64) and distances (441-5183 pc) from Gaia DR3 data to determine membership. We use ASteca to determine parameters for the clusters from our revised membership data. We define a quantifiable metric Modified Silhouette Score (MSS) to evaluate its performance. We study the dependence of MSS on age, distance, extinction, galactic latitude and longitude, and other parameters to find the particular cases when GMM seems to be more efficient than other methods. We compared GMM for nine clusters with varying ages but we did not find any significant differences between GMM performance for younger and older clusters. But we found a moderate correlation between GMM performance and the cluster distance, where GMM works better for closer clusters. We find that GMM does not work very well for clusters at distances larger than 3 kpc.

Determinants of board membership in Publicly-Owned Enterprises

Board structure is considered one of the most important determinants of board effectiveness. This study examines the personal motives of individuals seeking board membership in Publicly-Owned Enterprises (POEs). Using the sequential mixed methods approach, thirteen in-depth interviews were conducted with current and former board members, and one hundred and thirty-seven (137) questionnaires were administered to key representatives and beneficiaries of POEs. The results indicate several factors that motivate board membership. We find that intrinsic motives, which we refer to as ‘personal benefits,’ and extrinsic motives, which we refer to as ‘social recognition,’ are the most important factors for joining POE board membership. The findings could be helpful in redesigning strategies and policies for appointing professional board members whose primary incentives for board membership are related to POE development rather than personal benefits and self-recognition.

Regional convergence in the European Union – Factors of growth between the great recession and the COVID crisis

In this paper, we provide a new look at convergence in the EU while focusing on development at the regional level between the Great Recession and the recent COVID crisis. We use the log t convergence test by Phillips and Sul (2007) to analyze convergence in income level among the European regions. We identified five convergence clubs rather than supporting the overall convergence hypothesis. Furthermore, we investigated the determinants of convergence club membership using logistic regression. Our results confirmed high inequality within the member states and a shifting geographic pattern of the top-performing regions, with the increasing prominence of the manufacturing core in southern Germany and the surrounding areas. We found a positive association between membership in higher clubs, research and patent activities, and specialization in manufacturing. We also confirmed the positive economic performance of capital cities and the main metropolitan areas.

Determinants of dairy cooperative membership among smallholder farmers in North-Western Ethiopia

Determinants of dairy cooperative membership among smallholder farmers in North-Western Ethiopia

Joint trajectories of physical activity, self-rated health and income in Finnish statutory retirees

Abstract Background Health behaviours, health and socioeconomic position, particularly income, are known to change during ageing. However, no previous study has examined how they develop together over statutory retirement transition. We aimed to examine this joint development and to identify determinants of distinct groups. Methods We examined former employees of the City of Helsinki, Finland, who retired statutorily 2000-2022 (n = 4384, 79% women). We used five repeated questionnaire surveys to examine the joint developmental patterns in key indicators of healthy ageing and wellbeing: self-rated health, leisure-time physical activity and household income. We used joint group-based trajectory analysis to identify latent developmental groups and average marginal effects to examine determinants of the trajectory group membership. Results We found four distinct groups describing the joint developmental patterns. Group 1 (23%) had consistently poor health, little physical activity, and low, although slightly increasing income levels. Group 2 (34%) had first good but then declining health, average physical activity, and low but slightly increasing income. Group 3 (13%) had good health and very high level of physical activity, but average and fluctuating income. Group 4 (30%) had first good but then declining health, stable rather low physical activity and sharply increasing and high income. People with obesity had 23% (95% CI 22-26) higher likelihood of belonging to the Group 1 as compared to people with normal weight. They were also more likely with low education. Conclusions Over a follow-up of more than 20 years, we identified distinct groups among statutory retirees regarding their development of physical activity, self-rated health and income. Public health interventions to improve well-being and narrow health inequalities during ageing need to consider this heterogeneity and target policies considering people with different developmental patterns in their well-being. Key messages • Changes in income did not develop jointly with changes in health. Most statutory retirees had relatively good health, despite the development in leisure-time physical activity and household income. • Decline in physical activity could reflect decreasing intensity. Social and health-related factors show associations with the trajectory memberships, reflecting the known inequalities in health.

A behavioural analysis of post-pandemic modality profiles for non-commuting trips in the greater Toronto Area

As restrictions implemented to curb the spread of COVID-19 are being lifted and daily life is returning to “normal”, there is a need to understand whether changes brought about by the pandemic will persist in the post-pandemic period. In particular, understanding how individuals’ modal preferences are expected to evolve can help the development of policies that anticipate future needs and improve resilience towards future pandemics. Using web-based survey data collected in July 2021, this paper presents a behavioural analysis into post-COVID-19 modality profiles among residents of the Greater Toronto Area. The focus of this study is non-commuting trips, which play an important role in individuals’ overall wellbeing, especially during the pandemic. Modality profiles were identified for three periods: pre-pandemic, pandemic, and post-pandemic using latent class analysis. A multinomial logistic regression model was also developed to investigate the determinants of post-pandemic profile membership. Among significant factors are socio-economic attributes and mobility tool ownership. Transition analysis between profiles suggests that a return to public transit to pre-pandemic levels can be expected. The pandemic also resulted in the increased prominence of private vehicles and active modes, which will also remain post-pandemic. In contrast, ride-sourcing and taxi services are likely to play a diminished role after the pandemic. Policies that promote the use of active modes are important in maintaining the increased role of walking and cycling and potentially attracting car users post-pandemic.

Trajectories of CVD medication after statutory retirement: contributions of pre-retirement sociodemographic, work and health-related factors: a register study in Finland

BackgroundCardiovascular diseases (CVDs) are prevalent in older people, but few studies focus on developmental patterns in CVD medication directly after transition to statutory retirement.We thus aimed to identify trajectories of CVD medication after retirement, and their sociodemographic, work and health-related determinants.MethodsWe used complete register data of former employees of the City of Helsinki, Finland. All who reached their statutory retirement in 2000–2013, with five-year follow-up data (n = 6,505, 73% women), were included. Trajectories of CVD medication were identified with group-based trajectory modelling using data from Finnish Social Insurance Institution’s reimbursement register. Sociodemographic, work and health-related determinants of trajectory group membership were analysed using multinomial logistic regression.ResultsSix trajectories of CVD medication were distinguished: "constant low" (35%), “late increase” (6%), “early increase” (5%), "constant high" (39%), "high and decreasing " (8%), and "low and decreasing” (7%). The majority (74%) of the retirees fell into the "constant low" and "constant high" categories. Lower occupational class and increased pre-retirement sickness absence were associated with the "constant high" trajectory. Further, those with lower educational attainment were more prone to be in the “early increase” trajectory.ConclusionsIndividuals in lower socioeconomic positions or with a higher number of pre-retirement sickness absence may be considered at higher risk and might benefit from early interventions, e.g. lifestyle interventions and interventions targeting working conditions, or more frequent monitoring.

Trajectories of kidney function and risk of mortality.

We aimed to identify patterns within the rate of kidney function decline, determinants of these patterns and their association with all-cause mortality risk in the general population. Participants aged ≥ 45 years with at least one assessment of creatinine-based estimated glomerular filtration rate (eGFR) taken between 1997 and 2018 were selected from a population-based cohort study. Analyses were performed using several distinct latent class trajectory modelling methods. Cumulative incidences were calculated with 45 years of age as the starting point. In 12062 participants (85922 eGFR assessments, mean age 67.0 years, 58.7% women, median follow-up 9.6 years), four trajectories of eGFR change with age were identified: slow eGFR decline [rate of change in mL/min/1.73m2 per year (RC), -0.9; 95% CI, -0.9 to -0.9; reference group], intermediate eGFR decline (RC, -2.5; 95% CI, -2.7 to -2.5) and fast eGFR decline (RC, -4.3; 95% CI, -4.4 to -4.1), and an increase/stable eGFR (RC, 0.3; 95% CI, 0.3 to 0.4). Women were more likely to have an increase/stable eGFR [odds ratio (OR), 1.94; 95% CI, 1.53 to 2.46] whereas men were more likely to have a fast eGFR decline (OR, 1.86; 95% CI, 1.33 to 2.60). Participants with diabetes, cardiovascular disease (CVD) or hypertension were more likely to have an intermediate or fast eGFR decline. All-cause mortality risks (cumulative incidence at age of 70 years) were 32.3% (95% CI, 21.4 to 47.9, slow eGFR decline), 6.7% (95% CI, 3.5 to 12.4, intermediate eGFR decline), 68.8% (95% CI, 44.4 to 87.8, fast eGFR decline) and 9.5% (95% CI, 5.5 to 15.7, increase/stable eGFR). Sex, hypertension, diabetes and CVD were identified as trajectory membership determinants. Having fast eGFR decline was associated with the highest risk of all-cause mortality, highlighting the need for extensive monitoring and prevention of kidney function decline in individuals at risk of having fast eGFR decline.

Heterogeneity of preferences and breeders’ willingness to pay for improved livestock system in Benin, West Africa

The productivity of livestock, including small ruminants, in Benin, is very low, and their management practices in terms of feeding, health and reproduction do not ensure their optimal production. This research aimed to assess the willingness of sheep and goat keepers to pay for an improved breeding system. Data collection from 118 sheep and 375 goat breeders selected in six agroecological zones of Benin was undertaken using the choice experiments. The mixed logit model revealed heterogeneity in the preferences of small ruminant keepers for breeds, feeding practices, health treatments and reproductive control. This heterogeneity of preferences was confirmed by the latent class logit model results, which revealed the existence of four classes of sheep breeders and three classes of goat breeders. Irrespective of species, small ruminant breeders were generally willing to use herbal medicine or combine it with modern veterinary medicine and adopt Sahelian breeds or crossbreeds (Sahelian x Djallonke). They were not willing to adapt neither zero grazing nor controlled reproduction. The combination of the coefficient estimates of the latent class logit model and the determinants of class membership showed that herders in southern Benin with small and monospecific herds were the most willing to introduce changes in their breeding system.

CODEX: Role of velocity substructure in the scaling relations of galaxy clusters

Context. The use of galaxy clusters as cosmological probes relies on a detailed understanding of their properties. They define cluster selection and ranking linked to a cosmologically significant cluster mass function. Previous studies have employed small samples of clusters, concentrating on achieving the first calibrations of cluster properties with mass, while the diversity of cluster properties has been revealed via detailed studies. Aims. The large spectroscopic follow-up on the CODEX cluster sample with SDSS and NOT enables a detailed study of hundreds of clusters, lifting the limitations of previous samples. We aim to update the spectroscopic cluster identification of CODEX by running the spectroscopic group finder on the follow-up spectroscopy results and connecting the dynamical state of clusters to their scaling relations. Methods. We implemented a reproducible spectroscopic membership determination and cleaning procedures, based on the redMaPPer membership, running the spectroscopic group finder on the follow-up spectroscopy results and cleaning the membership for spectroscopic outliers. We applied the Anderson-Darling test for velocity substructure and analysed its influence on the scaling relations. We also tested the effect of the X-ray-to-optical centre offset on the scaling relations. Results. We report on the scaling relations between richness, X-ray luminosity, and velocity dispersion for a complete sample of clusters with at least 15 members. Clusters with velocity substructure exhibit enhanced velocity dispersion for a given richness and are characterized by 2.5 times larger scatter. Clusters that have a strong offset in X-ray-to-optical centres have comparable scaling relations as clusters with substructure. We demonstrate that there is a consistency in the parameters of the scaling relations for the low- and high-richness galaxy clusters. Splitting the clusters by redshift, we note a decrease in scatter with redshift in all scaling relations. We localize the redshift range where a high scatter is observed to z < 0.15, which is in agreement with the literature results on the scatter. We note that the increase in scatter for both high- and low-luminosity clusters is z < 0.15, suggesting that both cooling and the resulting active galactic nucleus feedback are at the root of this scatter.

Between voluntarism and compulsion: Membership in mutual health insurance societies in Swedish manufacturing, c. 1900

AbstractMembership in mutual health insurance societies spread among industrial workers in the late nineteenth century. We study determinants of such membership among male workers in Swedish manufacturing by using matched employer–employee data from three industries covering all workers (i.e. members and non‐members, N > 12 000) and firms around 1900. We find remarkably high rates of membership overall, and especially among married workers. The association between marital status and health insurance suggests that selection into health insurance societies was ‘propitious’ rather than ‘adverse’. Many workers became members well before the age of 40 years, when their health began to deteriorate, and this coincided with the average age of first marriage for men, occurring in their late twenties. Being married and having membership was more marked in firms with voluntary membership and was important for the viability of the mix of voluntary and compulsory health insurance societies emerging in Nordic countries around 1900. Findings support the idea that health insurance can attract high levels of membership under voluntary schemes and suggest why it took so long before statutory health insurance covering sickness absence and workplace accidents was introduced in Sweden.

A machine-learning-based tool for open cluster membership determination in Gaia DR3

Context. Membership studies characterising open clusters (OCs) with Gaia data – most of them using Gaia Data Release 2 (DR2) – have so far been limited at the faint end to magnitude G = 18 due to astrometric uncertainties. Aims. Our goal is to extend current OC membership lists with faint members and to characterise the low-mass end. These low-mass members are important for many applications, in particular for ground-based spectroscopic surveys. Methods. We use a deep neural network architecture to learn the distribution of highly reliable OC member stars around known clusters. We then use the trained network to estimate new OC members based on their similarities in a high dimensional space, their five-dimensional astrometry, and information from the three photometric bands. Results. Due to the improved astrometric precision of Gaia Data Release 3 (DR3) with respect to DR2, we are able to homogeneously detect new faint member stars (G > 18) for the known OC population. Conclusions. Our methodology can provide extended membership lists for OCs down to the limiting magnitude of Gaia, which will enable further studies to characterise the OC population; such as estimation of their masses and dynamics. These extended membership lists are also ideal target lists for forthcoming ground-based spectroscopic surveys.

Adolescent determinants of life-course leisure-time vigorous physical activity trajectories: a 27-Year longitudinal study

BackgroundAdolescence is regarded as formative years for building the foundations for life-long health and well-being, and adolescent determinants of physical activity (PA) development is particularly interesting. Novel approaches for the study of PA development, such as group-based trajectory modelling, opens for the possibility of identifying different patterns in the relationship among several known determinants of PA. This study aimed to explore how demographic, psychological and social factors in early adolescence determine membership in four distinct leisure-time vigorous physical activity (LVPA) trajectories from 13 to 40 years.MethodsThis study is based on data from the Norwegian Longitudinal Health Behaviour Study, following a cohort born in 1977 from Western Norway. Four trajectories identified using latent class growth analysis, based on self-reposted LVPA (n = 1103, 45.5% women) measured ten times from age 13 to age 40 and 17 different adolescent determinants, were used in a multivariate multinomial logistic regression.ResultsWe found that gender (male), VPA intentions the next year and athletic identity associated with belonging to the two trajectories reporting the highest levels of LVPA in adolescence, while VPA intentions in ten years were associated with belonging to the active trajectory compared to the decreasingly active and low active trajectories Enjoyment increased the odds of belonging to the increasingly and decreasingly active trajectories compared to the low active trajectory. In addition, two of the social determinants, mother’s PA and emotional support from father, were associated with belonging to the increasingly active trajectory when compared to the low active trajectory. Higher family income increased the odds of belonging to the increasingly active compared to the decreasingly active trajectory.ConclusionsBoth demographic, psychological, and social factors were identified as determinants of LVPA trajectory membership, and the findings support previous research related to the importance of intentions, but also indicate that enjoyment, role modelling and emotional support in PA can be of great importance to LVPA promotion among adolescents.

Diversity, solidarity and the construction of the ingroup among (post)colonial migrants in The Netherlands, 1945–1968

ABSTRACT Concerns about the impact of immigration (‘diversity’) on welfare states (‘solidarity’) are widespread among political economists. This article presents an alternative theoretical framework for understanding their relationship. Using social and cultural theory, I argue that it is tautological to suggest that diversity and solidarity covary; both emerge out of the same ideological and material efforts to construct an ‘ingroup.’ I probe this theory with a historical case study of the inclusion of (post)colonial migrants in the Netherlands from 1945 to 1968. Complementing secondary literature with original archival research, I show key state and non-state agents of the emergent Dutch welfare state constructing racial categories by fixing ‘Westernness’ or ‘rootedness’ as a salient determinant of ingroup membership, locating (post)colonial migrants in relation to it, and distributing entry, citizenship and social rights accordingly. An elusive metric of cultural proximity, ‘Westernness’ was under construction at the same time as it was in use, as state officials, social workers, and private charities negotiated its meaning with the public. The article not only compels European welfare scholarship to acknowledge race and racism in its recent past, but also builds theory regarding the influence of identity on redistributive outcomes.

Investigation of open cluster NGC 7789 using GAIA EDR3 data

We present the membership determination of the NGC 7789 open cluster located at Cassiopeia. Based on the astrometric data from Gaia Early Data Release 3 (positions, parallaxes, and proper motions) are considered to derive cluster members of the open cluster. The Hierarchical Density-Based Spatial Clustering of Applications with Noise and Gaussian Mixture Model techniques in determining the frequency and degree of a star’s membership in a cluster were being utilized in the study. We calculate the parallax and distance of the NGC 7789 cluster center to be 0.1994 ± 0.11 mas and 18637 ± 333110 pc respectively. The cluster center is calculated to be α = 359° 16' 56.44'', δ = 56° 42''38.46 ' and proper motion to be µα = −1.386 ± 0.68 mas/yr and µδ = −1.052 ± 0.37 mas/yr. We also utilized the Automated Stellar Cluster Analysis tool and obtained: log(age) = ~9.20, distance modulus (m-M)v =0.6516, reddening E(B V)=0.26±0.28, and metallicity [Fe/H] = −0.26, respectively. The stars in NGC 7789 show very little movement on proper motion and might be caused by fainter observations.

The new detection of blue straggler stars in 50 open clusters using Gaia DR3

Context. The particularly abundant presence of blue straggler stars (BSS) in Galactic open clusters offers favorable conditions for detailed studies on the statistical properties and the origin of the blue straggler population. With the help of Gaia DR3, the number of identified open clusters continuously increases, and the determination of star cluster members is more reliable. Aims. We performed a more thorough search for BSS in newly found open clusters based on Gaia data. Methods. We implemented a uniform membership determination for over one thousand newly identified open clusters with larger sky coverage based on the astrometric and photometric data from Gaia DR3. The membership probabilities of stars were assigned by the pyUPMASK algorithm. Then we estimated the physical parameters of these clusters by isochrone fitting on their CMDs and picked out BSS in the specific region of these CMDs. Results. We identified 138 BSS that had not been reported before in 50 open clusters. Conclusions. Compared with recent catalogs that present more than 1500 BSS in 339 open clusters, our new catalog increased the number of BSS in Galactic open clusters by about 10%, and the number of open clusters with BSS by nearly 17%. In the future, more accurate abundance measurements are anticipated to better probe the origin of BSS in open clusters.

Perceptions of friendship, peers and influence on adolescent smoking according to tobacco control context: a systematic review and meta-ethnography of qualitative research

BackgroundA relationship between smoking and interpersonal influences has been well established within the literature. There have been cultural shifts in denormalisation and a reduction in tobacco smoking in many countries. Hence there is a need to understand social influences on adolescents’ smoking across smoking normalisation contexts.MethodsThe search was conducted in July 2019 and updated in March 2022 within 11 databases and secondary sources. Search terms included schools, adolescents, smoking, peers, social norms and qualitative research. Screening was conducted by two researchers independently and in duplicate. Study quality was assessed using the eight-item Evidence for Policy and Practice Information and Co-ordinating Centre (EPPI-centre) tool for the appraisal of qualitative studies. Results were synthesised using a meta-narrative lens for meta-ethnography and compared across smoking normalisation contexts.ResultsForty one studies were included and five themes were developed, mapping onto the socio ecological model. The social processes by which adolescents take up smoking differed according to a mixture of school type, peer group structure and the smoking culture within the school, as well as the wider cultural context. Data available from smoking denormalised contexts, described changes in social interactions around smoking to cope with its stigmatisation. This was manifested through i) direct peer influence, whereby subtle techniques were employed, ii) group belonging whereby smoking was less likely to be seen as a key determinant of group membership and smoking was less commonly reported to be used as a social tool, and iii) popularity and identity construction, whereby smoking was perceived more negatively in a denormalised context, compared with a normalised context.ConclusionsThis meta-ethnography is the first study to demonstrate, drawing on international data, that peer processes in adolescent smoking may undergo changes as smoking norms within society change. Future research should focus on understanding differences across socioeconomic contexts, to inform the adaptation of interventions.

Individual-level determinants of current trade union membership and previous trade union membership in European countries

AbstractThis article aimed to explore the individual-level determinants of current and previous trade union memberships and to question if certain patterns are prevalent among European countries. Accordingly, repeated logit models across 15 European countries are applied drawing on the ninth round of the European Social Survey data. Variables are selected primarily considering the supply–demand theory, which explains the union membership based on the idea that employees are seeking to maximise the utility through cost and benefit analysis. In this context, this article offers a comprehensive analysis of the determinants of trade union membership with findings suggesting that personal, occupational and workplace characteristics affect current membership while occupational and workplace characteristics have effects with inverse directions on current membership and previous membership.

Unbound stars hold the key to young star cluster history

Aims.Gaia delivers the positions and velocities of stars at an unprecedented precision. Therefore, for star clusters, there exists much higher confidence in whether a specific star is a member of a particular cluster or not. However, membership determination is still especially challenging for young star clusters. At ages 2−10 Myr, the gas is expelled, ending the star formation process and leading to their expansion, while at the same time, many former members become unbound. As a first step, we aim to assess the accuracy of the methods commonly used to distinguish between bound and unbound cluster members; after identifying the most suitable technique for this task, we wish to understand which of the two populations is more suited to provide insights into the initial configuration and the dynamical history of a cluster starting from its currently observed properties. Methods. Here, we perform N-body simulations of the dynamics of such young star clusters. We investigate how cluster dynamics and observational limitations affect the recovered information about the cluster from a theoretical perspective. Results. We find that the much-used method of distance and velocity cutoffs for membership determination often leads to false negatives and positives alike. Often observational studies focus on the stars remaining bound. However, bound stars quickly lose the memory of the pre-gas expulsion phase due to their ongoing interaction with their fellow cluster members. Our study shows that it is the unbound stars that hold the key to charting a cluster’s dynamic history. Backtracking unbound stars can provide the original cluster size and determine the time of gas expulsion – two parameters that are currently still poorly constrained. This information is lost in the bound population. In addition, former members are often better indicators for disc lifetimes or initial binary fractions. We apply the backtracking analysis, with varying success, to the clusters: Upper Scorpius and NGC 6530. For highly substructured clusters such as Upper Scorpius, backtracking to the individual subcluster centres will provide better results in future.