Search

Superstars exist in classrooms and workplaces. Superstars can intimidate others and create a negative performance shock, or they can encourage others by inspiring everybody to "step up their game." In this study, we examine two effects: the impact of head-to-head competition with a superstar (direct) effect and the influence of a superstar presence on players' performance (indirect) effect. We find that the direct superstar effect in theory and in the data is always negative. The indirect superstar effect is neutral in theory, but depends on the intensity of the superstar in the data: if the skill gap between the superstar and the rest is small (large), there is a positive (negative) indirect effect. [ABSTRACT FROM AUTHOR]

• Social Context biases the ability to detect risk in emerging adults. • Ventral prefrontal and dorsomedial cortices show differential activity during risk discrimination. • Brain activity patterns show a social/non-social organization dependent on social context. • Functional connectivity between these social/non-social areas predicts the performance in a motorcycle simulation. The human brain contains social areas that become active when interacting with another human. These are located in the ventral prefrontal and mediodorsal cortices, adjacent to areas involved in reward processing and cognitive control. Human behaviour is strongly influenced by the social context. This is particularly evident when observing greater risk propensity in the presence of a peer, particularly during adolescence and emerging adulthood. We explored the widely held view that enhanced risk propensity is the consequence of weak cognitive control. We used brain activity, estimated from EEG recordings in a sample of 114 emerging adult dyads whilst performing a risk perception task, to predict risk behaviour in a subsequent driving simulation task. Being with a peer reduced the ability to discriminate riskiness in images of traffic scenes, biased responses towards the perception of no-risk, and increased the rate of accidents in the driving simulation. Risk perception involved three sets of clusters showing activity only when being with a peer, only when being alone, and in both social contexts. Functional connectivity between the clusters accounted for the later driving simulation performance depending on the peer's presence. In the light of our findings, greater risk-taking, when a peer is present, seems to be triggered by the activation of a different, less efficient brain network for risk-processing. [ABSTRACT FROM AUTHOR]

Many studies have examined the diffusion of health care innovation but less is known about the diffusion of health care fraud. In this paper, we consider the diffusion of potentially fraudulent Medicare home health care billing in the United States during 2002–16, with a focus on the 21 hospital referral regions (HRRs) covered by local Department of Justice (DOJ) anti-fraud "strike force" offices. We hypothesize that patient-sharing across home health care agencies (HHAs) provides a mechanism for the rapid diffusion of fraudulent strategies. We measure such activity using a novel bipartite mixture (or BMIX) network index, which captures patient sharing across multiple agencies and thus conveys more information about the diffusion process than conventional unipartite network measures. Using a complete population of fee-for-service Medicare claims data, we first find a remarkable increase in home health care activity between 2002 and 2009 in many regions targeted by the DOJ; average billing per Medicare enrollee in McAllen TX and Miami increased by $2127 and $2422 compared to just an average $289 increase in other HRRs not targeted by the DOJ. Second, we establish that the HRR-level BMIX (but not other network measures) was a strong predictor of above-average home health care expenditures across HRRs. Third, within HRRs, agencies sharing more patients with other agencies were predicted to increase billing. Finally, the initial 2002 BMIX index was a strong predictor of subsequent changes in HRR-level home health billing during 2002–9. These results highlight the importance of bipartite network structure in diffusion and in infection and contagion models more generally. • In some regions, Medicare home health care billing rose > 3-fold over 2002–2009. • A theoretical model linking home health agencies billing to their regional network. • Novel bipartite measure for the regional network of home health agencies. • The bipartite network measure strongly predicts regional home health billing. • There is evidence of peer-associations in agencies billing and treatment practices. [ABSTRACT FROM AUTHOR]