Perceived group cohesion versus actual social structure: A study using social network analysis of egocentric Facebook networks

Research on group cohesion often relies on individual perceptions, which may not reflect the actual social structure of groups. This study draws on social network theory to examine the relationship between observable structural group characteristics and individual perceptions of group cohesion. Leveraging Facebook data, we extracted and partitioned the social networks of 109 participants into groups using a modularity algorithm. We then surveyed perceptions of cohesion, and computed group density and size using social network analysis. Out of six linear mixed effects models specified, a random intercept and fixed slope model with group size as a predictor of perceived group cohesion emerged as best fitting. Whereas group density was not linked to perceived cohesion, size had a small negative effect on perceived cohesion, suggesting that people perceive smaller groups as more cohesive. We discuss the potential of social network analysis, visualization tools, and Facebook data for advancing research on groups

Acquaintances or Familiar Strangers?:How Similarity and Spatial Proximity Shape Neighbour Relations within Residential Buildings

While scholars have long established that city dwellers choose with whom to develop relationships on the basis of social proximity, spatial proximity remains the basis for neighbour relations involving greetings, social conversation, and the exchange of services. Few studies have systematically compared the respective roles of spatial and social proximity in neighbour relations. In this paper, we investigate these two factors through statistical analysis of four social network datasets representing relationships within four rented apartment buildings in Geneva, Switzerland. Using a measure of distance that takes into account how the layout and materiality of buildings shape relationships through accessibility, visibility and audibility, we compare the effects of spatial proximity with the effects of individual determinants and similarity. Our study also breaks new ground by comparing weak ties–between people who interact regularly–and “invisible ties”, or ties to familiar strangers. Our study confirms that spatial proximity increases the likelihood of weak ties and questions the underlying mechanisms. It also shows that in addition to sociability, familiarity and anonymity are constitutive dimensions of neighbouring, even at the scale of buildings.</p

As iron sharpens iron: A mentoring approach to labour market integration for humanitarian migrants

Integration of humanitarian migrants into the labour market is crucial for the long-term success of EU Member States. Previous research suggests that mentoring may be a viable labor market integration strategy. This paper tests the impact of mentoring among Arabic speaking humanitarian migrants in Germany, Greece and Italy. Results show that respondents who were mentored exhibited an increased probability of being employed, particularly when there was an educational component to the mentoring or when meaningful interpersonal connections were formed. This study provides first-hand evidence that mentoring promotes gainful employment as well as elucidates the pathways of its success

Whom do we lose? The case of dissimilarity in personal networks

Previous research finds that individuals tend to form ties with similar others much more often than with dissimilar others. However, we know relatively little about tie loss and to what extent this is driven by (dis)similarity. In this paper, we argue that ties to persons who are dissimilar with regard to gender, age, ethnicity, and education are lost faster than ties to similar persons – and we test three explanations for this faster decay of ties with dissimilar others: lack of meeting opportunities, preferences for similarity, and lower network embeddedness. To test these explanations, we analysed two waves of the Survey on the Social Networks of the Dutch (SSND, 2007, 2014). These SSND-waves contain comprehensive longitudinal panel data on ego networks of 441 respondents, who were interviewed about a wide range of relationships, their alters’ sociodemographic characteristics, where and when they met their alters, as well as how and whether they maintain these relationships. We modelled tie loss by event history analyses. Results show that ties to persons who were dissimilar are more likely to be lost faster, and that tie loss occurs mostly in the early years of a relationship. However, meeting opportunities, preferences for similarity, and network embeddedness are unable to explain why ties to dissimilar others are lost faster. We conclude that dissimilarity is a powerful driver of tie loss, and that more arguments and research are needed to fully understand the underlying mechanisms

Freak Waves in Random Oceanic Sea States

Freak waves are very large, rare events in a random ocean wave train. Here we study the numerical generation of freak waves in a random sea state characterized by the JONSWAP power spectrum. We assume, to cubic order in nonlinearity, that the wave dynamics are governed by the nonlinear Schroedinger (NLS) equation. We identify two parameters in the power spectrum that control the nonlinear dynamics: the Phillips parameter $\alpha$ and the enhancement coefficient $\gamma$. We discuss how freak waves in a random sea state are more likely to occur for large values of $\alpha$ and $\gamma$. Our results are supported by extensive numerical simulations of the NLS equation with random initial conditions. Comparison with linear simulations are also reported.Comment: 7 pages, 6 figures, to be published in Phys. Rev. Let

Taking stock and re-examining the role of science communication

Eight science communication research projects have been funded by the European Commission since 2018. These projects are a response to one of the European Commission's 'Science with and for Society' (SwafS) funding calls ¿ 'SwafS-19: Taking stock and re-examining the role of science communication.' Together these projects have received almost ¿10 million in research funding, and each has been affected to some extent by the COVID-19 global pandemic. This paper provides an overview of the eight projects, how they adapted to the challenges caused by the pandemic, and the subsequent implications for science communication policy and research funding

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements