Peer Clusters Research Articles

Universal School-Based Substance Use Prevention Using Technology-Supported Cooperative Learning.

Substance use in adolescence is a significant public health issue, particularly in early-to-mid adolescence, which represents a window of risk in the etiology of substance abuse and dependence. Substance use during this development period often results from affiliation with deviant peers, who model, facilitate, and reinforce use. Existing school-based substance use prevention programs have historically aimed to build adolescent knowledge regarding the dangers of substance use and/or enhance peer refusal skills. Research finds that these programs have had some success in reducing substance use, but meta-analyses report that average effect sizes are small. In a small one-year cluster randomized trial (12 middle and high schools; N = 813 students; ClinicalTrials.gov: NCT04478240), cooperative learning (CL) was implemented with the support of specialized technology and evaluated for its ability to reduce deviant peer affiliation and, in turn, reduce substance use. CL is a structured approach to small-group learning that provides at-risk youth with the opportunity to build friendships with more prosocial youth, interrupting the process of deviant peer clustering. Multi-level modeling revealed intervention effects for deviant peer affiliation and alcohol use across the sample, while tobacco use was significantly reduced among non-White students; intervention effects for marijuana use were only marginally significant. Effects for dosage were found for all outcomes, suggesting that every lesson taught had a significant impact. We conclude that CL, delivered with the aid of specialized technology, represents a viable option for universal substance use prevention. Future research should attempt to combine this approach with evidence-based prevention curricula.

Multi-objective optimization based demand response program with network aware peer-to-peer energy sharing

Demand-side energy management programs, such as Demand Response (DR) and Peer-to-Peer (P2P) energy sharing, have recently begun to be implemented to optimize the integration of distributed clean energy resources and to leverage generation and demand-side flexibility in the distribution system. In general, if not optimally planned, P2P energy sharing may have a negative impact on power distribution utilities’ primary objectives, such as minimizing energy losses, flattening the load profile, and improving voltage regulation. The DR program is considered as one of the potential mechanisms to alleviate the possible adverse impact of P2P energy sharing while maintaining the interest of peers participating in decentralized energy sharing. The analysis of the impact of P2P energy sharing with varying peers’ physical locations involved utilizing the Voltage Sensitivity Factor (VSF). The influence on the distribution network is contingent upon the difference in VSF values among the individual peers engaged in energy sharing. This study introduced the k-Means algorithm for VSF-based peer clustering, thereby generating the merit order and realizing the network-aware P2P energy transactions for the selected scenarios. A multi-objective optimization model-based real-time pricing-based DR scheme has been formulated to address the adverse impact of P2P energy sharing. Furthermore, this study quantifies the impact of DR potentials, which vary from 5% to 45% in increments of 10%, on the Peak-to-Average Ratio (PAR), overall energy loss, and total energy cost reduction. The modified IEEE 33 bus system incorporating industrial, commercial, and residential consumers’ load profile of 24 h at selected buses has been considered to test and validate the proposition.

Costs and benefits of cooperative learning as a universal school-based approach to adolescent substance use prevention.

Substance use during early adolescence implies a greater likelihood of abuse and dependence in later adolescence or adulthood. In turn, substance abuse and dependence are linked to a variety of maladaptive long-term health-related outcomes that imply significant individual and societal costs. In this paper, we evaluated an approach to substance use prevention that relies on the vital role of peers, who comprise a key risk factor for adolescent substance use. This approach (i.e., cooperative learning, CL) focuses on interrupting the process of deviant peer clustering and providing at-risk youth with the opportunity to build social skills and cultivate friendships with low-risk youth. In addition to testing the efficacy of CL in reducing the number of students who become regular substance users, we also conducted a cost-benefit analysis. Using four waves of data from a cluster-randomized trial (N = 15 middle schools, 1890 students, 47.1% female, 75.2% White, 13.9% of students were receiving special education services), we found that significantly lower percentages of students in the intervention (CL) schools became regular users of tobacco, alcohol, and marijuana. We estimated that the reduction in substance use associated with the implementation of CL resulted in total lifetime benefits of between $1027 and $4621 per student (in 2019 dollars), or between $8.79 and $39.54 for each dollar invested in CL. Benefit/cost ratios would go up to $22.54-$101.39 per dollar invested with the continual implementation of CL, assuming retraining every 5 years. Implications and future research directions are discussed.

Time and position aware resource search algorithm for the mobile peer-to-peer network using ant colony optimisation

The progressive growth of wireless mechanisms and the wide popularity of intelligent devices are attracting particular attention to peer-to-peer mobile ad hoc networks (P2P MANET). Increasing the efficiency to search the resources became an important research topic in the P2P MANETs. Most existing research gives more emphasis on position-based clustering techniques and does not give preference to time. Due to not giving any preference to time, the existing approaches are not so appropriate to improve the efficiency to search the resources in P2P MANETs. This paper suggests a navel resource search approach that first uses position-aware peer clustering strategy. Then, using an ant colony optimisation method with pheromones, it chooses the preeminent neighbour's peer that is of time-aware neighbouring peer's resource preferences and the time-aware neighbouring peer's availability. Based on the results of the experiment, this approach outweighs other approaches in terms of search delay, overhead traffic, and search success rate.

A Cooperative Peer Clustering Scheme for Unstructured Peer-to-Peer Systems

A Cooperative Peer Clustering Scheme for Unstructured Peer-to-Peer Systems

A Cooperative Peer Clustering Scheme for Unstructured Peer-to-Peer Systems

A Cooperative Peer Clustering Scheme for Unstructured Peer-to-Peer Systems

P2P Data Dissemination for Real-Time Streaming Using Load-Balanced Clustering Infrastructure in MANETs With Large-Scale Stable Hosts

In order to reduce the network overhead in data dissemination between large-scale stable users in mobile ad-hoc networks (MANETs), clustering is a typical method by partitioning the peers into a hierarchical infrastructure. In the article, a peer-to-peer data dissemination mechanism for real-time streaming based on the hierarchical infrastructure in MANETs will be proposed. First, a distinct strategy of peer clustering is adopted to maximize network capacity and meet peer traffic demand. The peer clustering problem is formulated as a 0/1 integer linear programming (ILP). Then, an approximation algorithm is proposed to determine the feasible solution of the 0/1 ILP. Second, in order to provide timely data dissemination among peers, another method for estimating propagation delay is proposed, where we use the estimated value and the actual historical value simultaneously to alleviate the incorrect problem of the estimated value. Third, based on the quality of service (QoS) requirement of the service, a different distributed data scheduling algorithm between peers is designed, which effectively utilizes the limited bandwidth of the network. The simulation results show that the proposed mechanism obtains a higher network capacity and higher data received rate than the previous works.

Diversity on British boards and personal traits that impact career progression from AIM towards FTSE 100

This study proposes a new approach to examining executive remuneration and manager characteristics disaggregated by market index peer clusters and analyses personal attributes that differentiate managers across companies of different market caps (proxied my market indices such as FTSE 100, FTSE 250, FTSE SmallCap, and AIM). Our sample is composed of biographical data on 790 executive directors from 125 UK financial firms covering a 2004-2016 time period. The results show that network and education are the most important factors for career progression. On average, FTSE 100 executive directors are three times better connected and two times better educated than FTSE SmallCap and AIM board members. The larger the firm, the more diverse the board with more international (non-British) and female directors (even though male executives mostly dominate). The higher position is associated with greater age, while new executives tend to be younger and better connected. We highlight a change in the new managers’ skill-set after the financial crisis which may presumably be explained by risk aversion. New directors appointed after 2008 are, on average, older and better educated. Even though after the crisis we document that all the boardrooms, except FTSE SmallCap, appear to have become more gender diverse, the female presence in the boards is scarce and the highest number of women was mainly employed during the financial crisis. After 2008, British boards have become less nationality diverse. Thus, for the purpose of maintaining companies’ competitive advantage in increasingly diverse markets, it requires further attention from policy regulators.

Cooperative learning effects on peer relations and alcohol use in middle school

We tested a prevention approach aimed at reducing growth in alcohol use in middle school using four waves (2 years) of data from a cluster randomized trial (N = 15 middle schools, 1890 students, 47.1% female, 75.2% White). Our approach exposed students to a broad cross-section of peers through collaborative, group-based learning activities in school (i.e., cooperative learning). We hypothesized that the increased social contact created by cooperative learning would promote greater peer relatedness, interrupting the process of deviant peer clustering and, in turn, reducing escalations in alcohol use. Our results supported these hypotheses, suggesting that the social nature of cooperative learning, and the emphasis on group work and collaboration, can provide social and behavioral as well as academic benefits for students.

Dynamic pathways between rejection and antisocial behavior in peer networks: Update and test of confluence model.

The confluence model theorizes that dynamic transactions between peer rejection and deviant peer clustering amplify antisocial behavior (AB) within the school context during adolescence. Little is known about the links between peer rejection and AB as embedded in changing networks. Using longitudinal social network analysis, we investigated the interplay between rejection, deviant peer clustering, and AB in an ethnically diverse sample of students attending public middle schools (N = 997; 52.7% boys). Adolescents completed peer nomination reports of rejection and antisocial behavior in Grades 6-8. Results revealed that rejection status was associated with friendship selection, and adolescents became rejected if they were friends with others who were rejected. Youth befriended others with similar levels of AB. Significant patterns of peer influence were documented for AB and rejection. As hypothesized, rejected youth with low AB were more likely to affiliate with others with high AB instead of similarly low AB. In contrast, nonrejected youth preferred to befriend others with similarly high or low AB. Results support an updated confluence model of a joint interplay between rejection and AB as ecological conditions that lead to self-organization into deviant clusters in which peer contagion on problem behaviors operates.

Comparison of US County-Level Public Health Performance Rankings With County Cluster and National Rankings

Health departments can be grouped together based on sociodemographic characteristics of the population served. Comparisons within these groups can then help with monitoring and improving the health of their populations. To compare county-level percentile rankings on outcomes of smoking, motor vehicle crash deaths, and obesity within sociodemographic peer clusters vs nationwide rankings. This cross-sectional, population-based study of demographic and health data from the 2014 Behavioral Risk Factor Surveillance System and the 2016 Robert Wood Johnson Foundation County Health Rankings data set was conducted at 3139 of 3143 US counties and county-equivalents. Four locations were excluded due to incomplete data. Data analysis was conducted between January and August 2017. Random forest algorithms were used to identify sociodemographic characteristics most associated with the outcomes of interest. These characteristics were race and ethnicity, educational attainment, age, marital status, employment status, sex, and health insurance status. k-means clustering was used to cluster counties based on these sociodemographic characteristics and the percentage of the county classified as rural. County-level smoking prevalence, motor vehicle crash death rate, and obesity prevalence. County percentile rankings on the outcomes of interest were compared in the national context and the within-cluster context. A total of 318 856 967 individuals (mean [SD] individuals per county, 101 579.2 [326 315]; 161 911 910 women [50.8%]) were represented by the 3139 counties used in this analysis. Eight distinct sociodemographic clusters throughout the United States were found. Cluster-specific percentile rankings for both smoking prevalence and motor vehicle crash death rates improved more than 70 percentile points for several counties in the rural, American Indian cluster compared with the nationwide percentiles. Conversely, the young, urban, middle to high socioeconomic status cluster included counties with cluster-specific percentile rankings that declined by 60 percentile points or more compared with the nationwide rankings for all 3 outcomes of interest. Comparing county health outcomes on a nationwide or statewide basis fails to adequately account for sociodemographic context. Clustering counties by sociodemographic factors related to the outcome of interest allows a better understanding of other factors that may be shaping the prevalence of health outcomes. These groupings may also aid learning exchange.

Peer influence processes as mediators of effects of a middle school substance use prevention program

BackgroundPeer influence processes have been linked to escalation in substance use during the middle school years, particularly among at-risk youth. In this study, we report on an approach to prevention that attempts to counteract peer influence by interrupting the process of deviant peer clustering, in which socially marginalized youth self-aggregate and reinforce delinquent behavior, including substance use. We aimed to interrupt this process by implementing collaborative, group-based learning activities in school (i.e., cooperative learning). MethodsIn a cluster randomized trial in the Pacific Northwest (N = 1460 7th-grade students in 15 schools), we tested whether cooperative learning can reduce alcohol and tobacco use, and whether these effects are mediated by reductions in the amount of alcohol and tobacco use among one's friends. Intervention schools were provided with training in cooperative learning, and data were collected in September/October 2016 (baseline) and March 2017 (follow-up). ResultsResults indicated that cooperative learning significantly lowered rates of growth in alcohol (β = −0.60 [−0.36|−0.84]; p < .001) and tobacco use (β = −0.58 [−0.21|−0.94]; p = .01) between baseline and follow-up in intervention schools as compared to control schools. These effects were mediated by reductions in the prevalence of alcohol and tobacco use, respectively, among self-selected friends. ConclusionsCooperative learning was able to significantly reduce the prevalence of both alcohol and tobacco use in friendship networks during the school year. The lower prevalence of alcohol and tobacco use among friends, in turn, reduced individual use at follow-up.This study was registered as trial NCT03119415 in ClinicalTrials.gov.

Enlisting Peer Cooperation in the Service of Alcohol Use Prevention in Middle School.

This article reports on a cluster randomized trial of cooperative learning (CL) as a way to prevent escalation in alcohol use during middle school (N=1,460 seventh-grade students, age 12-13, seven intervention and eight control schools). We hypothesized that CL, by bringing students together in group-based learning activities using positive interdependence, would interrupt the process of deviant peer clustering, provide at-risk youth with prosocial influences, and in turn, reduce escalations in alcohol use. Results indicated that CL significantly reduced growth in deviant peer affiliation and actual alcohol use, and effects for willingness to use alcohol were at the threshold of significance (p=.05). CL also attenuated the link between willingness to use alcohol and later alcohol use.

Being a Girl Mathematician: Diversity of Positive Mathematical Identities in a Secondary Classroom

The construction of positive mathematical identities (MIs) is a complex and central issue in school mathematics, where girls are usually “counted out” of the field. This study explores positive MIs (high achiever and positive relationship with mathematics) of 3 girls. We employed a nested model of identity based on a case study approach (i.e., female mathematics students nested within a cluster of students nested within a mathematics classroom). The results highlight diversity in how these girls experienced mathematics: They valued different forms of doing mathematics (independent and collaborative; wider and complex; and straightforward, procedure-oriented mathematics), showed different forms of engagement (detachment, protagonist and challenging, and compliant and support-seeker), and narrated different MIs (efficient, different, and responsible). The study also explores and discusses the roles of mathematical practice and belonging to different peer clusters in these different forms of identification.

The social exigencies of the gateway progression to the use of illicit drugs from adolescence into adulthood

BackgroundThere is limited empirical integration between peer clustering theory and the Gateway framework. The goal of the present study was to test the hypothesis that friendship associations partly predict gateway escalations in the use of drugs from adolescence to adulthood. MethodThis longitudinal study analyzed 3 waves of data from a community sample of 711 male and female participants without a history of illicit drug use reporting drug use at age 17, 22, and 27. Substance use assessments including tobacco, alcohol, cannabis, onset and abuse/dependence tendency of illicit drugs other than cannabis (i.e., cocaine, methamphetamine, and opiates), and friends' reported use of illicit drugs. Structural equation modeling was used to test the hypothesized model. ResultsParticipants' cannabis use level at age 17 was positively associated with perceived friends' drug use at age 22, which in turn predicted participants' onset of illicit drug use between ages 22 and 27. Moreover, progression of tobacco use throughout age 17 to 22 was associated with an increased onset of illicit drug use between ages 22 and 27. Apart for an effect of cannabis use at age 22 on abuse and dependence tendency to various drugs at age 28, results were similar. ConclusionsDuring this period of development, the availability and selection of drug-using friends contributes to the progression to potentially more rewarding and damaging illicit drugs. These findings suggest the need to attend to the peer ecology in prevention and support the common practice of using abstaining peers in treatment for drug dependence.

The Influence of Social Network Characteristics on Peer Clustering in Smoking: A Two-Wave Panel Study of 19- and 23-Year-Old Swedes.

ObjectivesThe present study examines how the composition of social networks and perceived relationship content influence peer clustering in smoking, and how the association changes during the transition from late adolescence to early adulthood.MethodsThe analysis was based on a Swedish two-wave survey sample comprising ego-centric network data. Respondents were 19 years old in the initial wave, and 23 when the follow-up sample was conducted. 17,227 ego-alter dyads were included in the analyses, which corresponds to an average response rate of 48.7 percent. Random effects logistic regression models were performed to calculate gender-specific average marginal effects of social network characteristics on smoking.ResultsThe association of egos’ and alters’ smoking behavior was confirmed and found to be stronger when correlated in the female sample. For females, the associations decreased between age 19 and 23. Interactions between network characteristics and peer clustering in smoking showed that intense social interactions with smokers increase egos’ smoking probability. The influence of network structures on peer clustering in smoking decreased during the transition from late adolescence to early adulthood.ConclusionsThe study confirmed peer clustering in smoking and revealed that females’ smoking behavior in particular is determined by social interactions. Female smokers’ propensity to interact with other smokers was found to be associated with the quality of peer relationships, frequent social interactions, and network density. The influence of social networks on peer clustering in smoking decreased during the transition from late adolescence to early adulthood.

VITAL: Structured and clustered super-peer network for similarity search

VITAL is a novel P2P indexing structure that provides on top of exact search a similarity search of multidimensional vectors. It is designed to scale to millions of peers and billions of shared documents and to adapt to high network dynamics. To exploit peer heterogeneity, VITAL is a super-peer (SP) network where every peer is an SP candidate and a simple election protocol is run to select SPs. On the other hand, every SP locally monitors its “vital” signs of memory, processing, and bandwidth and initiates the SP election protocol based on its capacity and load limits. In addition, the SP overlay is structured as CAN distributed hash table to guarantee both the correctness and responsiveness of the query protocol. A novel data replication model is introduced, where every peer clusters its shared documents to local clusters (LCs) and each LC summary is published at few SPs to achieve content-based clustering and firework query propagation. Every peer establishes TCP connections with many SPs that maintain its LC summaries. VITAL has no central component and does not require global knowledge, however it requires identifying a set of global cluster (GC) centriods to be disjointly managed by the elected SPs. In addition, CAN zone overloading is seamlessly applied to relief overwhelmed SPs and it provided an extra layer of physical proximity clustering. The scalability analysis shows that peer index requires less than 3 % of extra storage and a query (on average) can be satisfied by visiting 1.6 % of the number of established TCP connections.

An ant-based approach to cluster peers in P2P database systems

Peer-to-Peer (P2P) systems with distinct advantages such as scalability, robustness and low cost have developed quickly in recent years. The resource search problem, that is to find out a peer having a desired resource, is a fundamental problem to be initially solved in most P2P applications. P2P systems can also be categorized under database systems. One of the most important problems of P2P database systems is the query processing algorithms. Even a rather small improvement over these algorithms can have a significant impact on the performance of a P2P database system. One of the most effective methods to reduce query processing cost is peer clustering. Hence, clustering peers with similar contents makes the queries directed to the appropriate cluster and thus to be efficiently answered. In this paper, we present a new peer clustering algorithm for P2P database systems that uses ant-based clustering algorithms. We have adjusted ant-based clustering algorithm to peer clustering problem. Performance evaluation of the algorithm shows its strength in clustering peers in P2P database systems to be of a higher quality and accuracy compared to the existing systems, to have a relatively short running time and to quickly converge to an optimum. Moreover, our algorithm achieves a high scalability to the increasing problem size.

A Brief Measure of Peer Affiliation and Social Acceptance (PASA): Validity in an Ethnically Diverse Sample of Early Adolescents

The purpose of this study was to conduct a multiagent–multimethod analysis of the validity of a brief measure of deviant peer affiliations and social acceptance (PASA) in young adolescents. Peer relationships are critical to child and adolescent social and emotional development, but currently available measures are tedious and time consuming. The PASA consists of a youth, parent, and teacher report that can be collected longitudinally to study development and intervention effectiveness. This longitudinal study included 998 middle school students and their families. We collected the PASA and peer sociometrics data in Grade 7 and a multiagent–multimethod construct of deviant peer clustering in Grade 8. Confirmatory factor analyses of the multiagent–multimethod data revealed that the constructs of deviant peer affiliations and social acceptance and rejection were distinguishable as unique but correlated constructs within the PASA. Convergent, discriminant, concurrent, and predictive validity of the PASA was satisfactory, although the acceptance and rejection constructs were highly correlated and showed similar patterns of concurrent validity. Factor invariance was established for mother reports and for father reports. Results suggest that the PASA is a valid and reliable measure of peer affiliation and of social acceptance among peers during the middle school years and provides a comprehensive yet brief assessment of peer affiliations and social acceptance.

Adolescent deviant peer clustering as an amplifying mechanism underlying the progression from early substance use to late adolescent dependence

Early substance use co-occurs with youths' self-organization into deviant peer groups in which substance use is central to social interaction. We hypothesized that the social dynamics of deviant peer groups amplify the risk of progressing from early use to later dependence, and that this influence occurs over and above escalations in use that typically accompany early substance use and membership in deviant groups. Our study used a longitudinal, multimethod dataset consisting of 998 adolescents and their families. Participants were recruited from middle schools in a large metropolitan area in the Pacific Northwest. The sample was 47.3% female and ethnically diverse (42.3% European American, 29.1% African American, and 28.6% other, including biracial). We examined deviant peer clustering as a mediator between early substance use and later dependence, controlling for proximal levels of use, SES, early antisocial behavior, and parental monitoring. Tobacco, alcohol, and marijuana use were assessed at ages 12, 13, and 16-17. Past-year nicotine, alcohol, and marijuana dependence (DSM-IV) was assessed at age 19. Youth and parent reports and observational data were used to assess deviant peer clustering at age 16-17, and youth reported on antisocial behavior and parental monitoring at ages 12 and 13. Early substance use predicted increased likelihood of dependence on tobacco, alcohol, and marijuana by late adolescence. Deviant peer affiliation mediated these links, even when accounting for proximal levels of substance use. Early substance use not only promotes escalations in use across adolescence but also provides entry into a deviant social context that contributes to increased risk of dependence. Our results emphasize the importance of identifying and intervening in early substance use before it becomes an organizing factor in friendship selection and interaction. Deviant peer clusters are clearly an important avenue for intervention when seeking to interrupt the progression to substance dependence.