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PubMedDate not supplied

MatrixExplorer: a dual-representation system to explore social networks.

MatrixExplorer is a network visualization system that uses two representations: node-link diagrams and matrices. Its design comes from a list of requirements formalized after several interviews and a participatory design session conducted with social science researchers. Although matrices are commonly used in social networks analysis, very few systems support the matrix-based representations to visualize and analyze networks. MatrixExplorer provides several novel features to support the exploration of social networks with a matrix-based representation, in addition to the standard interactive filtering and clustering functions. It provides tools to reorder (layout) matrices, to annotate and compare findings across different layouts and find consensus among several clusterings. MatrixExplorer also supports Node-link diagram views which are familiar to most users and remain a convenient way to publish or communicate exploration results. Matrix and node-link representations are kept synchronized at all stages of the exploration process.

Algorithms↗
PubMed1995

Gender differences in the relationship between social network support and mortality: a longitudinal study of an elderly cohort.

Despite well-recognized gender differences in patterns of social network support, few studies have explored whether the pathways by which social support affects mortality risk differ for men and women. In a 15-year follow-up study of elderly HMO members, we found that network size affected men's mortality risk indirectly, through their health status, while no such indirect effect was found for women. The data also suggested that network size had a direct protective effect on mortality risk for both men and women, with men gaining protection at a lower level of network size than women. These findings confirm the need for a gender-specific approach to further research on this subject, and suggest the need to measure variables that capture the different meaning and value of social network participation for men and women.

Aged↗
PubMed1992

Social network and activities in relation to mortality from cardiovascular diseases, cancer and other causes: a 12 year follow up of the study of men born in 1913 and 1923.

OBJECTIVE: The aim was to examine the relationship between social network and activities and causes of death. DESIGN: The study was a prospective cohort study of middle aged men examined in 1973 and followed for 12 years. SETTING: Gothenburg, Sweden. SUBJECTS: The subjects were 769 60 year old and 220 50 year old men who had participated in a health examination. MEASUREMENTS AND MAIN RESULTS: Main outcome measures were mortality from cardiovascular diseases, cancer and other causes. In multivariate analyses cardiovascular mortality was related to baseline blood pressure (p less than 0.001), smoking habits (p = 0.002), myocardial infarction or stroke (p less than 0.001), and a low level of social activities (p = 0.04). Cancer mortality was related to age (p = 0.003) and smoking habits (p = 0.001). Other causes of death were related to poor perceived health (p = 0.02) and a low level of home activities (p = 0.004). In univariate analyses the above risk factors were strongly related to all three causes of death. In addition cardiovascular mortality was related to age, a low level of home and outside home activities, few persons in the household, and poor perceived health. Cancer mortality was related to poor perceived health, few persons in the household, and a low level of social activities. Other causes of death were related to living alone, poor perceived health, and a low level of social and outside home activities. CONCLUSIONS: Well known risk factors for premature mortality like smoking, hypertension, and major cardiovascular disease are verified. Middle aged men with a good "social network" (here measured as a high level of social, home, and outside home activities) may be partly protected against non-cancer mortality.

Blood Pressure↗
PubMed2002

Being popular can be healthy or unhealthy: stress, social network diversity, and incidence of upper respiratory infection.

Diverse social contacts are generally associated with better health. However, diverse contacts can increase exposure to infectious agents. This should increase risk for disease, particularly among those whose host resistance is otherwise compromised (e.g., stressed individuals). In this prospective study, healthy college students who completed questionnaires assessing social network diversity and stressful life events were subsequently interviewed weekly for 12 weeks to track incidence of upper respiratory infections (URIs). URI episodes were defined by a symptom criterion and by clinically verified self-reported illness. Stress and diversity of social contacts interacted; diversity was associated with more illnesses among those with more stressful life events and slightly fewer illnesses among those with fewer stressful life events. Associations remained after controlling for neuroticism.

Adolescent↗
PubMedDate not supplied

[The condition of families of patients with schizophrenia in Italy: burden, social network and professional support].

OBJECTIVE: This study aimed to describe: a) the interventions received by patients with schizophrenia attending Italian mental health services (MHS); b) the relatives' burden and social network and the professional support received by the families. DESIGN: The study has been carried out in 30 MHS, randomly selected and stratified by geographic areas and population density. 25 patients with a DSM-IV diagnosis of schizophrenia and 25 relatives were recruited in each MHS. Family burden was evaluated in relation to: a) geographic area; b) interventions received by the patients; c) social and professional support received by the families. MAIN OUTCOME MEASURES: a) patients: Brief Psychiatric Rating Scale (BPRS) and Disability Assessment Interview (AD); b) key-relatives: Family Problems Questionnaire (QPF) and Social Network Questionnaire (QRS); c) interventions received by the patients and their families: Scheda di Rilevazione degli Interventi--Pattern of Care Schedule (SRI). RESULTS: Data on 709 patients and their key-relatives were collected. In the two months preceding the data collection, 35% of patients attended rehabilitative programmes; 80% of the families were in regular contact with the MHS and 8% received family psychoeducational interventions. Family burden was higher in Southern than in Central and Northern Italy. This difference disappeared when rehabilitative interventions and family support were provided. CONCLUSIONS: This study highlights that the situation of the families of patients with schizophrenia is more burdensome in Southern Italy and is greatly influenced by the type of interventions provided by the MHS.

Adolescent↗
PubMed1999

Logit models and logistic regressions for social networks: II. Multivariate relations.

The research described here builds on our previous work by generalizing the univariate models described there to models for multivariate relations. This family, labelled p*, generalizes the Markov random graphs of Frank and Strauss, which were further developed by them and others, building on Besag's ideas on estimation. These models were first used to model random variables embedded in lattices by Ising, and have been quite common in the study of spatial data. Here, they are applied to the statistical analysis of multigraphs, in general, and the analysis of multivariate social networks, in particular. In this paper, we show how to formulate models for multivariate social networks by considering a range of theoretical claims about social structure. We illustrate the models by developing structural models for several multivariate networks.

Humans↗
PubMed2004

Social network correlates of self-reported non-fatal overdose.

The leading cause of death among heroin users is drug overdose. The present study examined the relationship between history of self-reported drug overdoses and social network characteristics among cocaine and opiate users. Data were from cross-sectional surveys administered from March 2001 through February 2003 as part of follow-up of an experimental network oriented HIV prevention intervention. A total of 838 participants with histories of cocaine and opiate use completed the survey. Several social network variables were found to be significantly associated with drug overdose in the prior 2 years, including larger number of network members who were injection drug users and a larger number of conflictual ties among the network members. Even after controlling for age, gender, frequency of injection drug and alcohol use, and health status, network variables continued to have a strong association with history of recent overdose. These data suggest that large drug networks should be targeted for drug overdose prevention interventions.

Adult↗
PubMed1999

Social network characteristics associated with risky behaviors among runaway and homeless youth.

Runaway and homeless youth are at high risk for substance abuse and unsafe sexual behavior. Our study describes the personal social networks of these youth and examines network characteristics associated with risky behaviors. In 1995 and 1996, we interviewed a purposive sample of youth aged 14 through 21 who were living in Washington, DC and were identified on the streets or through shelters or other service agencies (N = 327). Although we found that most youth reported current social relationships, a significant minority (26%) did not. Youth without a social network were significantly more likely to report current illicit drug use, multiple sex partners, and survival sex than youth with a network. For youth with a network, the networks were small, strong in affective and supportive qualities, comprised primarily of friends, typically included an alcohol or illicit drug user, and usually were not a source of pressure for risky behaviors. Our results indicate that networks had risk-enhancing and risk-decreasing properties in that network characteristics were associated in both positive and negative directions with risky behaviors.

Adolescent↗
PubMed2000

Influences of socioeconomic status, social network, and competence on subjective well-being in later life: a meta-analysis.

Meta-analysis is used to synthesize findings from 286 empirical studies on the association of socioeconomic status (SES), social network, and competence with subjective well-being (SWB) in the elderly. All three aspects of life circumstances are positively associated with SWB. Income is correlated more strongly with well-being than is education. The quality of social contacts shows stronger associations with SWB than does the quantity of social contacts. Whereas having contact with friends is more strongly related to SWB than having contact with adult children, there are higher associations between life satisfaction and quality of contact with adult children when compared with quality of friendships. Moderating influences of gender and age on the effects of SES, social network, and competence on SWB are also investigated.

Aged↗
PubMed1982

Social networks, beliefs, and the decision to seek medical care: an analysis of congruent and incongruent patterns.

This article focuses on the impact of congruent and incongruent patterns of symptom specific beliefs and social network advice on the decision to seek medical care for symptoms. Data from 769 individuals who reported symptoms in the Los Angeles Health Survey are used to examine this issue. Further, the role of more general health orientations and social network influences in the decision to seek care is examined under these congruent and incongruent conditions. It is concluded that the more general factors, which have little effect on the aggregate, may play a role in decision making when beliefs and advice are incongruent. Further, it is concluded that reports of beliefs and advice about specific symptoms that have been given after the decision has been made to seek care may be valid and not the result of retrospective reconstruction.

Attitude to Health↗
PubMed1997

Weapon carrying among black adolescents: a social network perspective.

OBJECTIVES: This report describes the salience of social networks to the phenomena of adolescent weapon carrying. METHODS: A random-walk network sampling design was used to survey 113 adolescents about topics, including weapon carrying. RESULTS: In a probability sample of 12- to 15-year-olds, 20.9% reported ever carrying a weapon. Carriers were eight times as likely as noncarriers to report weapon carrying by an older associate, and 19 times as likely to report weapon carrying by a peer. A significant dose-response effect was present. CONCLUSIONS: This evidence supports the interpretation that modeling of weapon carrying by personal network members is important for its initiation and maintenance in adolescence.

Adolescent↗
PubMed1994

[Family ecology, social networks and suicidal behavior in the school milieu].

This article sums up the outcome of a research project conducted in Montreal schools in 1987 and 1988, and focusing on how family ecology and social networks relate to strong suicidal tendencies among teenagers. Two groups were involved in the study: one with 78 suicidal persons, the other with 72 non-suicidal persons. Teenagers in each group were interviewed separately. All subjects reported high lack of attention from at least one of the two parents. Results also show that parents of suicidal teens experience permanent break-ups less frequently in comparison to the other group. However, families of suicidal teens tend to experience deeper changes in the structure of the family unit following an initial separation. With respect to moving, there are no significant differences, whether in the number of moves or the important people, have access to as many different kinds of support and report the same number of conflicts. In all these comparisons, however, suicidal teenagers do name a proportionately higher number of adults. This leads the authors to hypothesize that a higher rate of parental separation among non-suicidal teens could represent a protective factor rather than a vulnerability factor, as is usually suggested. In terms of social networks, the fact that suicidal teens seek out adults to a greater degree could impede on their socializing with peers and, therefore, on their social integration.

Adolescent↗
PubMedDate not supplied

Specificity and substitution in the social networks of the elderly.

A set of hypotheses is developed with regard to the way that life cycle, cultural, and structural factors serve to delimit and specify the psychological desires satisfied through interaction with the various categories of others in an elderly person's social network. A second set of hypotheses focuses upon the extent to which the absence of the social category of persons most relevant for the satisfaction of a particular desire can be compensated for by persons from another category. Data are presented which largely support both sets of hypotheses. The findings point to the importance of diversity in the social networks of the aged. Although some substitution of relationships may take place, in the present study no one type of relationship, whether with a spouse, adult children, siblings, confident friends, or organizational acquaintances, was able to satisfy all three of the psychological desires considered.

Adaptation, Psychological↗
PubMed1995

Survey of the social networks of people with severe mental health problems.

The social functioning of people with severe mental health problems is an indicator of general physical and emotional well-being. There exists a wealth of literature on the topic from the professional carer's perspective but relatively little from the perspective of the clients themselves. Thirty clients were interviewed in order to explore their understanding of the nature and value of the social networks in which they were currently involved. Despite having participated in a variety of rehabilitation interventions, these clients remained insecure and lacking in confidence. They had few friends beyond members of their immediate family and were generally leading lonely, friendless existences without the capacity to establish new relationships. Although this study suggests that clients often have grandiose plans for the future, mental health nurses may best meet their needs by helping to sustain existing relationships and using them at all levels of therapeutic intervention, rather than attempting to nurture new relationships for which clients are unready and the failure of which may result in a relapse in clients' mental health status.

Adult↗
PubMed2002

Rural-urban differences in sociodemographic, social network and lifestyle factors related to mortality of middle-aged Japanese men from the Komo-Ise cohort study.

To examine rural-urban differences in the relationships of sociodemographic, social network, and lifestyle factors to mortality in middle-aged men, we used the data from a community based prospective cohort study, the Komo-Ise study. The subjects were all men aged 40-69 years living in Komochi Village, the rural group (n=2,295), or the downtown district of Isesaki City, the urban group (n=3,334), as of 1993. They completed a self-administered questionnaire in 1993 and were followed for all-cause deaths until 2000. The Cox proportional hazards model was used to compute relative risks (RRs) with 95% confidence intervals (CIs). Low educated men and men without a spouse in the rural group had an increased risk of mortality (RR=4.4; 95%CI: 1.1-18.2, RR=2.4; 95%CI: 1.2-4.5). Men who did not enjoy good fellowship with their neighbors in the rural group had a decreased risk of mortality (RR=0.58; 95%CI: 0.35-0.97). Mortality risks were significantly higher in urban men not participating in hobbies, club activities or community groups (RR=1.6; 95%CI: 1.1-2.4). These variables remained significant risk factors, even after controlling for all sociodemographic, social network, lifestyle, and health status variables. Educational level, marital status and relation to neighborhoods showed significant rural-urban differences.

Adult↗
PubMed2003

Individual, contextual, and social network factors affecting exposure to HIV/AIDS risk among older residents living in low-income senior housing complexes.

This study examines the influence of individual, contextual (building location and characteristics), and social network characteristics on HIV prevalence and risk behavior among people older than 50 years of age living in low-income senior housing in two cities, Hartford, Connecticut and Chicago, Illinois. The authors' study focuses on older residents of six buildings located in impoverished neighborhoods with high rates of HIV transmission through injection drug use and unprotected sexual activity, including the exchange of sex for drugs and money. The article is organized into three sections. First, the authors explore the HIV prevalence, distribution, and risk behaviors that may contribute to new infections among the buildings' older residents in general. These practices include unprotected sexual intercourse, sex with commercial sex workers, casual or multiple partners, regular use of alcohol and/or illicit drugs, and other high-risk activities that expose older residents to HIV, sexually transmitted diseases, and other negative health consequences. Next, the authors examine the relationship between building and neighborhood characteristics, the internal social organization of buildings, and the risk behaviors of individual residents by building residency. Finally, the authors use a social network analysis to identify possible entry points and transmission routes for HIV infection through drug and sexual exchanges between and among building residents and visitors. This approach also reveals variations in building structures that may facilitate the diffusion of HIV prevention efforts.

Acquired Immunodeficiency Syndrome↗
PubMed2003

The emergent properties of a dolphin social network.

Many complex networks, including human societies, the Internet, the World Wide Web and power grids, have surprising properties that allow vertices (individuals, nodes, Web pages, etc.) to be in close contact and information to be transferred quickly between them. Nothing is known of the emerging properties of animal societies, but it would be expected that similar trends would emerge from the topology of animal social networks. Despite its small size (64 individuals), the Doubtful Sound community of bottlenose dolphins has the same characteristics. The connectivity of individuals follows a complex distribution that has a scale-free power-law distribution for large k. In addition, the ability for two individuals to be in contact is unaffected by the random removal of individuals. The removal of individuals with many links to others does affect the length of the 'information' path between two individuals, but, unlike other scale-free networks, it does not fragment the cohesion of the social network. These self-organizing phenomena allow the network to remain united, even in the case of catastrophic death events.

Animals↗
PubMed1988

Social networks of disease spread in the lower Illinois valley: a simulation approach.

This study illustrates the use of disease modeling and simulation techniques to the study of the spread of disease within and between social networks. A Reed-Frost type model of disease spread is used to construct a simulation of the spread of tuberculosis within three prehistoric populations of the Lower Illinois River Valley during Middle Woodland, Late Woodland, and Mississippian times. A high and low population size was modeled for each time period. Late Woodland model 2 (low population estimate) is the only model that experienced pathogen extinction with host survival. The rest of the models experienced rapid and severe host population decline. The results of the simulation suggest that a social network size of between 180 and 440 persons is required under the conditions of this model for host-pathogen coexistence (i.e., endemicity) to occur. The severe population decline experienced by these populations suggests that tuberculosis as modeled here could not have existed in these populations. Future refinements of modeling and simulation techniques can provide additional insights into how disease spreads among social contacts.

History, Ancient↗