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PubMedDate not supplied

Preventing adolescent drug abuse and high school dropout through an intensive school-based social network development program.

Purpose. The hypothesis tested was that experimental subjects, relative to controls, would demonstrate significant increases in school performance and decreases in drug involvement at program exit (5 months) and at follow-up (10 months). Design. A two-group, repeated-measures, intervention trial was the design used. Setting. The study involved four urban Northwest high schools. Subjects. Participants included 259 youth at high risk of potential school dropout, 101 in the experimental group and 158 in the control group. Intervention. The Personal Growth Class experimental condition was a one-semester, five-month elective course taken as one of five or six regular classes. It had a 1:12 teacher-student ratio, and integrated group support and life-skills training interventions. The control condition included a regular school schedule. Measures. School performance measures (semester GPA, class absences) came from school records. Drug use progression, drug control, and adverse consequences were measured by the Drug Involvement Scale for Adolescents. Self-esteem, school bonding, and deviant peer bonding were measured using the High School Questionnaire: Inventory of Experiences. All multi-item scales had acceptable reliability and validity. Results. As predicted, trend analyses revealed significantly different patterns of change over time between groups in drug control problems and consequences; in GPA (but not attendance); and in self-esteem, deviant peer bonding, and school bonding. The program appeared to stem the progression of drug use, but group differences only approached significance. Conclusion. Program efficacy was demonstrated particularly for decreasing drug control problems and consequences; increasing GPA and school bonding; and desired changes in self-esteem and deviant peer bonding. Program effects on progression of drug use were less definitive.

Adolescent↗
PubMed1993

Empirical evidence for the Social Stress Model of Substance Abuse.

The Social Stress Model of Substance Abuse builds upon and integrates knowledge from numerous psychosocial theories and models. According to this model, the likelihood of an individual engaging in drug abuse is a function of the stress level and the extent to which it is offset by stress modifiers such as social networks, social competence, and resources. This article synthesizes current empirical evidence for this model. Thirty-five primary research studies are described, with special attention to the four psychosocial constructs inherent in the model: stress, social networks, social competence, and resources. Consistencies and inconsistencies in the findings, a critique of key methodological issues, and suggestions for future research are provided.

Humans↗
PubMed1990

Social support and quitting smoking for good. Is there an association? Results from the population study, "Men born in 1914," Malmö, Sweden.

The objective in this study was to analyse whether there is independent association between social network, social support, social influence and quitting smoking for good. The study sample (n = 621) comprised a random half of all male Malmö residents born in 1914, of which 500 (80.5%) participated. A new instrument based on a model with carefully defined and well differentiated concepts was used to measure different aspects of social network, social support and social influence. In logistic regression analysis, emotional support (an important aspect of social support) had an association to quitting smoking for good (odds ratio 3.1, 95% confidence interval 1.9-5.4), when adjustments were made for social class, marital status (spousal support), alcohol consumption, physical activity, smoking of spouse and different medical conditions. Emotional support reflects the individuals' opportunity for care, encouragement of personal value and feelings of confidence and trust. This may contribute to a deeper understanding of mechanisms behind smoking cessation and could be of importance in the field of health promotion, but also for improvement of the long-term results of smoking cessation programs and in our clinical work with patients who smoke.

Aged↗
PubMed2004

Modelling disease outbreaks in realistic urban social networks.

Most mathematical models for the spread of disease use differential equations based on uniform mixing assumptions or ad hoc models for the contact process. Here we explore the use of dynamic bipartite graphs to model the physical contact patterns that result from movements of individuals between specific locations. The graphs are generated by large-scale individual-based urban traffic simulations built on actual census, land-use and population-mobility data. We find that the contact network among people is a strongly connected small-world-like graph with a well-defined scale for the degree distribution. However, the locations graph is scale-free, which allows highly efficient outbreak detection by placing sensors in the hubs of the locations network. Within this large-scale simulation framework, we then analyse the relative merits of several proposed mitigation strategies for smallpox spread. Our results suggest that outbreaks can be contained by a strategy of targeted vaccination combined with early detection without resorting to mass vaccination of a population.

Contact Tracing↗
PubMedDate not supplied

Correlates of health-related quality of life in patients with heart failure.

BACKGROUND: The purpose of this study was to explore health-related quality of life (HRQOL) in patients with advanced heart failure undergoing heart transplantation evaluation. The overall aim of the study was to determine whether patients' demographic characteristics, functional status, neuroticism, social network, social support, spirituality, and time since symptom onset are related to the physical and mental components of a patient's HRQOL. METHODS: A descriptive, correlational design was used. Patients (N = 61) were recruited from 2 university-affiliated, outpatient, heart failure programs. Data were collected from chart review, a 6-minute walk, and patient-completed instruments. HRQOL, including physical and mental health components, was assessed with use of the Medical Outcomes Study 36-Item Short Form Health Survey (SF-36). RESULTS: Demographic characteristics, functional status, neuroticism, social network, social support, spirituality, and time since symptom onset explained 26% of the variability in the physical health component of HRQOL and 44% of the variability in the mental health component of HRQOL in patients with advanced heart failure. In analyzing the data for the most parsimonious model, New York Heart Association classification, 6-minute walk distance, and neuroticism explained 49% of the variability in the mental health component of HRQOL. CONCLUSIONS: New York Heart Association classification, 6-minute walk distance, and neuroticism are related to the mental health component of HRQOL and can be easily included in the assessment of patients with heart failure who are undergoing heart transplantation evaluation. The findings of the current study require replication but may be used to identify patients with heart failure who are potentially at risk for reduced HRQOL.

Activities of Daily Living↗
PubMed2004

Risk perceptions, condom use, and sexually transmitted diseases among adolescent females according to social network position.

BACKGROUND AND OBJECTIVES: Adolescent females are frequently treated as a homogenous group but could differ on their sexually transmitted disease (STD) risk because of individual attitudes and exposure through sexual networks. GOAL: The goal of this study was to determine if risk perceptions, condom use, and STD prevalence differs within sexual networks. STUDY DESIGN: Three hundred three adolescent females participating in a longitudinal study of adolescent STD risk perceptions and condom use were categorized as "core," "bridge," and "periphery" in a sexual network according to their and their main sex partner's risk information. Regression analysis determined differences in risk perceptions by network location. RESULTS: We demonstrated an inverse relationship between STD risk perceptions and network location. Adolescents with higher risk perceptions were more likely to use condoms, irrespective of network location. CONCLUSION: Female adolescents are a heterogeneous group exhibiting different risk perceptions. Different intervention strategies for adolescents at higher risk could be necessary. Interventions designed to raise risk perceptions could be associated with condom use, even for those adolescents at greatest risk.

Adolescent↗
PubMed2002

Contact tracing and epidemics control in social networks.

A generalization of the standard susceptible-infectious-removed stochastic model for epidemics in sparse random networks is introduced which incorporates contact tracing in addition to random screening. We propose a deterministic mean-field description that yields quantitative agreement with stochastic simulations on random graphs. Both the stochastic simulations and the mean-field equations show secondary epidemics if the contact tracing is not performed with sufficient strength. We also analyze the role of contact tracing in epidemics control in small-world networks and show that its effectiveness grows as the rewiring probability is reduced.

Journal Article↗
PubMed2005

Cooperation, social networks, and the emergence of leadership in a prisoner's dilemma with adaptive local interactions.

Cooperative behavior among a group of agents is studied assuming adaptive interactions. Each agent plays a Prisoner's Dilemma game with its local neighbors, collects an aggregate payoff, and imitates the strategy of its best neighbor. Agents may punish or reward their neighbors by removing or sustaining the interactions, according to their satisfaction level and strategy played. An agent may dismiss an interaction, and the corresponding neighbor is replaced by another randomly chosen agent, introducing diversity and evolution to the network structure. We perform an extensive numerical and analytical study, extending results in M. G. Zimmermann, V. M. Eguíluz, and M. San Miguel, Phys. Rev. E 69, 065102(R) (2004). We show that the system typically reaches either a full-defective state or a highly cooperative steady state. The latter equilibrium solution is composed mostly by cooperative agents, with a minor population of defectors that exploit the cooperators. It is shown how the network adaptation dynamics favors the emergence of cooperators with the highest payoff. These "leaders" are shown to sustain the global cooperative steady state. Also we find that the average payoff of defectors is larger than the average payoff of cooperators. Whenever "leaders" are perturbed (e.g., by addition of noise), an unstable situation arises and global cascades with oscillations between the nearly full defection network and the fully cooperative outcome are observed.

Journal Article↗
PubMed2006

Cultural propagation on social networks.

In this work we present a model for the propagation of culture on networks of different topology and by considering different underlying dynamics. We extend a previous model proposed by Axelrod by letting a majority govern the dynamics of changes. This in turn allows us to define a Lyapunov functional for the system.

Journal Article↗
PubMed2006

Preferential attachment in the growth of social networks: the internet encyclopedia Wikipedia.

We present an analysis of the statistical properties and growth of the free on-line encyclopedia Wikipedia. By describing topics by vertices and hyperlinks between them as edges, we can represent this encyclopedia as a directed graph. The topological properties of this graph are in close analogy with those of the World Wide Web, despite the very different growth mechanism. In particular, we measure a scale-invariant distribution of the in and out degree and we are able to reproduce these features by means of a simple statistical model. As a major consequence, Wikipedia growth can be described by local rules such as the preferential attachment mechanism, though users, who are responsible of its evolution, can act globally on the network.

Journal Article↗
PubMed1983

Autoerotic asphyxial deaths and social network response.

A study of 132 autoerotic asphyxial deaths revealed that family members and friends, in addition to experiencing shock over the sudden aspect of the death, frequently were the ones to discover the decedent's body and were confused by the sexual nature of the death. Clinicians are urged to be alert for signs of such potentially lethal sexual activity among the young people they see, and to be prepared to assist bereaved family members.

Adolescent↗