Bistability through triadic closure

We propose and analyse a class of evolving network models suitable for describing a dynamic topological structure. Applications include telecommunication, on-line social behaviour and information processing in neuroscience. We model the evolving network as a discrete time Markov chain, and study a very general framework where, conditioned on the current state, edges appear or disappear independently at the next timestep. We show how to exploit symmetries in the microscopic, localized rules in order to obtain conjugate classes of random graphs that simplify analysis and calibration of a model. Further, we develop a mean field theory for describing network evolution. For a simple but realistic scenario incorporating the triadic closure effect that has been empirically observed by social scientists (friends of friends tend to become friends), the mean field theory predicts bistable dynamics, and computational results confirm this prediction. We also discuss the calibration issue for a set of real cell phone data, and find support for a stratified model, where individuals are assigned to one of two distinct groups having different within-group and across-group dynamics

The effectiveness of teamwork training on teamwork behaviors and team performance : A systematic review and meta-analysis of controlled interventions

The objective of this study was to conduct a systematic review and meta-analysis of teamwork interventions that were carried out with the purpose of improving teamwork and team performance, using controlled experimental designs. A literature search returned 16,849 unique articles. The meta-analysis was ultimately conducted on 51 articles, comprising 72 (k) unique interventions, 194 effect sizes, and 8439 participants, using a random effects model. Positive and significant medium-sized effects were found for teamwork interventions on both teamwork and team performance. Moderator analyses were also conducted, which generally revealed positive and significant effects with respect to several sample, intervention, and measurement characteristics. Implications for effective teamwork interventions as well as considerations for future research are discussed

What Happens When the Party is Over?:Sustaining Physical Activity Behaviors after Intervention Cessation

Although extensive research suggests that behavior change interventions can improve physical activity (PA) over the course of an intervention, the maintenance of these improvements beyond intervention termination is less clear. The purpose of this study was to determine, through meta-analysis, whether behavior change interventions produce sustained improvements in PA after interventions conclude. Studies were retrieved from a recent (2019) meta-analysis of 224 interventions. Studies that measured PA at baseline, post-intervention, and a follow-up timepoint were included in this updated review. We examined the effects of these interventions in terms of changes in PA from baseline to post-intervention, baseline to follow-up, and post-intervention to follow-up (relative to control groups). We also examined whether the inclusion of theory and behavior change techniques (BCTs) within interventions as well as the length of time between PA assessments moderated these effects. Thirty-nine interventions (17% of interventions from the previous review) from 31 studies were included in the meta-analysis. Significant improvements in PA were found from baseline to follow-up (d = 0.32). In general, these effects resulted from significant increases in PA from baseline to post-intervention (d = 0.46), followed by significant decreases from post-intervention to follow-up (d = −0.18). Effect sizes did not vary between theory-based and no-stated-theory interventions. The positive effects from baseline to post-intervention and negative effects from post-intervention to follow-up were more pronounced as the length of time between assessments increased. In conclusion, behavior change interventions improve PA over the course of the intervention; however, these improvements are generally not sustained after the intervention concludes.</p

An evaluation of case study teaching materials on hazards: based on the current aims of geographical education

Hazards are an integral part of people-environment relationships. The impact of hazards locally and globally has become increasinglymore severe. particularly in the previous two decades. This is largely as a result of unwise human intervention in natural systems. The study of hazards at secondary school level affords valuable opportunities for learning about people-environment issues. This in turn, can promote a greater awareness of environmental problems. One of the most important current aims of Geographical Education is the development of critical thinking skills in pupils. Such skills are vital for equipping pupils with the necessary tools to understand and participate in solving the world's increasing human and environmental problems. The development of a critical faculty in pupils is best achieved by the use of learner-based participatory teaching strategies where pupils are involved in problem solving activities. Research has shown that British and South African Geography curricula reflect current thinking in Geographical education and learning theory. The 1992 Junior Secondary Geography Syllabus in line with these trends. includes a section for study on hazards. Hazards are presented primarily as case studies in modern Geographical texts. which is seen as one of the most effective ways of teaching hazards. Research however suggests that South African textbooks have certain shortcomings. notwithstanding the importance placed on textbooks by teachers in this country. This study investigated the extent to which case study teaching materials on hazards are optimising opportunities available for effective learning within an Environmental Paradigm. An evaluation methodology, which is believed to have value for use by other researchers, was developed to suit the specific requirements of the study. The study findings reveal a poor realisation of the current aims of Geographical Education and learning theory, regarding the South African teaching materials. Recommendations are made improvements in the development and use of local case teaching materials. Guidelines for the development of for study local materials are provided from case studies in British texts and from methods developed by the researcher

Severe convective storm risk in the Eastern Cape Province of South Africa

This study investigates the temporal, spatial and impact characteristics of severe convective storm hazard and risk in the Eastern Cape Province of South Africa. Using historical data on severe convective storms dating from 1897, patterns of the hazard threat and risk to various geographic populations were investigated. A conceptual framework that emphasises the combined role hazard and vulnerability play in defining risk was used for the study. A methodology for ranking the severity of the storms in the historical dataset, based on recorded damage/impact, was specifically developed for the study. It is intended that this methodology will have a potentially wider application and may be adapted to a range of hazard impact and risk studies in South Africa and internationally. The study was undertaken within the context of the South African Disaster Management Act of 2002. Findings of the study show that severe convective storms can occur throughout the province, but there are clearly demarcated areas of higher frequency and concentration. The impact of storms is particularly severe on impoverished and vulnerable rural populations in the eastern parts of the province, where there is an urgent need for building capacity in disaster risk management. A major outcome of the study is the production of a severe convective storm hazard/risk map of the Eastern Cape, which it is hoped will be of benefit to a number of stakeholders in the province, particularly disaster management, but also the South African Weather Service, agricultural organisations, development/planning authorities, educational authorities and risk insurers. It is hoped that this map and the study in general will assist in guiding the operational responses of the various authorities, especially in terms of those interventions aimed at disaster risk reduction in the Eastern Cape

Does error control suppress spuriosity?

In the numerical solution of initial value ordinary differential equations, to what extent does local error control confer global properties? This work concentrates on global steady states or fixed points. It is shown that, for systems of equations, spurious fixed points generally cease to exist when local error control is used. For scalar problems, on the other hand, locally adaptive algorithms generally avoid spurious fixed points by an indirect method---the stepsize selection process causes spurious fixed points to be unstable. However, problem classes exist where, for arbitrarily small tolerances, stable spurious fixed points persist with significant basins of attraction. A technique is derived for generating such examples

Teamwork training in sport:A pilot intervention study

The purpose of this study was to test the efficacy of a novel team building intervention that targets teamwork in sport. Using a 10-week pilot nonrandomized controlled intervention design, 12 interdependent sports teams comprising 187 athletes were assigned to one of two conditions: an experimental condition in which teams participated in two teamwork training sessions at Weeks 2 and 6 of the study (6 teams, 94 athletes) or a no-training control condition (6 teams, 93 athletes). Teamwork was measured at Weeks 1, 5, and 10 of the study. Overall, significant improvements in teamwork were shown for the experimental teams from baseline to Week 5; these effects were maintained through Week 10 of the study. In contrast, no significant changes in teamwork were observed for teams in the control condition over these 10 weeks. The results provide evidence that teamwork training can enhance the extent to which members of a sports team work effectively together