Stability of dyadic exchange: Experimental evidence for the impact of shared group membership.

Pair stability refers to the extent to which exchange occurs between the same actors over time. In a stable pair, actors know what to expect of one another and have a sense of predictability as to the outcome of the exchange. When actors are split into discrete groups, shared group membership contributes to formation of new ties and maintenance of existing ties due to the mechanism of attraction to similar others. Using the formal framework of biased net theory, we propose three hypotheses which link shared group membership with the odds of pair stability. These hypotheses are tested against data from an experiment (N = 180) in which participants were first split into two groups and then given a series of opportunities to share resources with one another. Results of the experiment are consistent with the hypotheses.

Modeling information diffusion in social media: data-driven observations.

Accurately modeling information diffusion within and across social media platforms has many practical applications, such as estimating the size of the audience exposed to a particular narrative or testing intervention techniques for addressing misinformation. However, it turns out that real data reveal phenomena that pose significant challenges to modeling: events in the physical world affect in varying ways conversations on different social media platforms; coordinated influence campaigns may swing discussions in unexpected directions; a platform's algorithms direct who sees which message, which affects in opaque ways how information spreads. This article describes our research efforts in the SocialSim program of the Defense Advanced Research Projects Agency. As formulated by DARPA, the intent of the SocialSim research program was "to develop innovative technologies for high-fidelity computational simulation of online social behavior ... [focused] specifically on information spread and evolution." In this article we document lessons we learned over the 4+ years of the recently concluded project. Our hope is that an accounting of our experience may prove useful to other researchers should they attempt a related project.

Experimental evaluation of baselines for forecasting social media timeseries.

Forecasting social media activity can be of practical use in many scenarios, from understanding trends, such as which topics are likely to engage more users in the coming week, to identifying unusual behavior, such as coordinated information operations or currency manipulation efforts. To evaluate a new approach to forecasting, it is important to have baselines against which to assess performance gains. We experimentally evaluate the performance of four baselines for forecasting activity in several social media datasets that record discussions related to three different geo-political contexts synchronously taking place on two different platforms, Twitter and YouTube. Experiments are done over hourly time periods. Our evaluation identifies the baselines which are most accurate for particular metrics and thus provides guidance for future work in social media modeling.

Sexual and gender minority undergraduates' relationships and strategies for managing fit in STEM.

Undergraduates with sexual and/or gender minority (SGM) identities, including lesbian, gay, bisexual, transgender, queer/questioning, pansexual, intersexual, asexual, or additional positionalities, often face an unwelcoming STEM microclimate. The STEM microclimate includes the places students experience, such as classrooms or labs, and the people, such as peers or professors, with whom they discuss their STEM program. While previous work offers a framework of microaggressions faced by SGM people, and the behavioral, cognitive, and emotional strategies they use to react to them, little is known about the strategies SGM students use to persist in the STEM microclimate. We analyze interviews with 29 SGM STEM undergraduates to uncover how they fit in STEM, their experiences that affect fit, how social capital in the form of influential others affects fit, and the strategies used to deal with microaggressions and cultivate a supportive network. Using thematic analysis, we find that students vary in their feelings of fit, with students with gender minority identities experiencing more frequent and more severe microaggressions than students with sexual minority identities (which are often less visible). We likewise find that students with racial minority identities report compounding issues related to identity. SGM students with social capital, or a network of people to whom they can turn in order to access advice and resources, believe they fit in better than those without such capital. To support their feelings of fit, students use defenses against discrimination, including micro-defenses, wherein they change how they present their self to avoid microaggressions and/or surround themselves with accepting people. This research highlights the role of microaggressions and social capital in affecting fit as well as the micro-defenses students use to defend against discrimination. Our introduction of the concept of micro-defenses provides a way to theorize about micro-interactional dynamics and the site at which students defend against microaggressions so they feel more welcome in STEM. Implications provide insight into how SGM students can be supported in STEM as well as the institutional changes STEM departments and campuses can make in order to better support and include SGM students.

The association between egocentric sexual networks and sexual meeting venues with PrEP conversation and encouragement for use among Latinx men who have sex with men.

Despite the increasing availability of pre-exposure prophylaxis (PrEP), Latinx men who have sex with men (LMSM) are not receiving PrEP-related information. To understand the influence of LMSM sexual networks on PrEP-related conversations and encouragement to use PrEP, this cross-sectional egocentric network study characterized the PrEP-related communication of 130 LMSM egos with 507 sexual partners (alters). Participants were recruited using respondent-driven sampling methods from a Miami-Dade County community-health organization. Egocentric-level data were collected from 2018-2019 and analyzed using multilevel modeling. Of egos, 30% reported using PrEP. Closeness between participants and sexual partners played a role in PrEP conversation and encouragement. Participants believed they would have less success convincing sexual partners to use PrEP if partners were older. Participants perceived higher likelihood to talk about PrEP or success in encouraging alters to use PrEP if, relative to meeting sexual partners on Grindr, they met at a friend's party, gay-centric community event, or school/work. Given that increased closeness and in-person sexual partner meeting venues are associated with PrEP information dissemination and encouragement, social network-based interventions can capitalize on PrEP navigators who run network visualizations, and with this information develop a longitudinal plan to increase PrEP conversation and encouragement as needed for each network.

The Association Between Homophily on Illicit Drug Use and PrEP Conversations Among Latino Men Who Have Sex with Men Friends: A Dyadic Network and Spatially Explicit Study.

Despite the wide availability of PrEP, Latino men who have sex with men (LMSM) continue to experience access barriers. Novel HIV prevention research strategies to increase PrEP uptake and adherence among the high incidence populations, such as LMSM who misuse drugs, include social network analyses. This study identified the associations of drug use homophily within LMSM friendship networks and PrEP promotion conversations and described the physical overlap between geographic drug risk areas with conversations of PrEP promotion. Respondent-driven sampling was used to recruit 10 sociocentric networks. Quadratic assignment procedure (QAP) correlations and multiple regression QAPs were used to identify influences of drug use homophily, and geocoding and visualizations to describe drug use polygons and PrEP conversations. Friendship relationships in which both friends used cocaine or marijuana were more likely to report PrEP-related conversations in the past six months. The likelihood of talking about PrEP in the next six months was higher among dyads with cocaine use homophily and ecstasy use homophily, while lower among dyads with marijuana use homophily. Participants reported using marijuana and cocaine throughout Miami-Dade County while ecstasy polygons were mostly in urban areas. The majority of drug polygons associated with PrEP conversations were located in north and central Miami. Future interventions can consider enrolling entire sociocentric friendship groups, configuring friendship networks to connect those without PrEP information to those with information, and incorporating peer leaders.

Why Re-Invent the Wheel? Social Network Approaches Can Be Used to Mitigate SARS-CoV-2 Related Disparities in Latinx Seasonal Farmworkers.

Latinx seasonal farmworkers are essential workers and are at elevated risk for SARS-CoV-2 in the United States. Risk factors for SARS-CoV-2 are unique to this population and include crowded living conditions, isolated social networks, and exploitative working environments. The circumstances and cultural values of Latinx seasonal farmworkers pose a unique challenge to public health authorities working to contain the spread of SARS-CoV-2. This community is in dire need of urgent public health research to identify opportunities to prevent SARS-CoV-2 transmission: social network methods could be the solution. Using previously collected and new information provided by a team of experts, this commentary provides a brief description of Latinx seasonal farmworker disparities that affect tracking and treating SARS-CoV-2 in this important group, the challenges introduced by SARS-CoV-2, and how social network approaches learned from other infectious disease prevention strategies can address these disparities.

The Association Between Social and Spatial Closeness With PrEP Conversations Among Latino Men Who Have Sex With Men.

BACKGROUND: US Latino men who have sex with men (LMSM) are a group at highest risk for HIV. One driver of HIV among LMSM is inadequate access to pre-exposure prophylaxis (PrEP) information. The social network theory of homophily suggests that sharing similar sociodemographic factors could influence PrEP conversations within networks. This study aimed to determine how the effects of homophily across sociodemographic, immigration, cultural, and PrEP-related factors are associated with PrEP-related communication. SETTING: This study was conducted in Miami-Dade County, FL. METHODS: Data collected between August 2018 and October 2019 included 10 sociocentric friendship groups of 13 LMSM (N = 130). Participants were recruited using respondent-driven sampling by a community-based organization in Miami. We used the multiple regression quadratic assignment procedure to identify the effects of homophily and relationship characteristics on PrEP-related conversations using R software. RESULTS: More frequent PrEP-related conversations were associated with dyadic friendships characterized by homophily on knowledge of PrEP effectiveness, heterophily on depressive symptom severity, home addresses proximity, friend closeness, and interaction frequency. Past PrEP-related conversation frequency also increased based on heterophily on the Latino cultural value of familism (ie, emotional support to family). Racial homophily, heterophily on severity of depressive symptoms, home addresses proximity, friendship closeness, and frequency of interactions increased likelihood to encourage a friend to use PrEP. DISCUSSION: Social and spatial closeness and homophily play a role in PrEP-related conversations. Information from social networks contextualized in geographic settings can be elucidated to contribute toward the design of novel opportunities to end HIV.

Social Capital From Professional Engineering Organizations and the Persistence of Women and Underrepresented Minority Undergraduates.

Professional engineering organizations (PEOs) have the potential to provide women and underrepresented and minoritized (URM) students with social capital (i.e., resources gained from relationships) that aids their persistence in their engineering undergraduate programs and into the workforce. We hypothesize that women and URM students engineering students who participate in PEOs are more likely to persist in their engineering major and that PEOs contribute to their persistence by providing them access to insider information that supports their persistence. Each year for five years we administered surveys with closed- and open-ended items to examine the association between participating in PEOs and the persistence of a cohort of engineering majors from 11 diverse universities. We used logistic regression and thematic analysis to analyze the data. URM students who participated in PEOs and other engineering related activities were more likely to persist to the second year than URM students who did not (adjusted odds ratio = 2.18, CI: 1.09, 4.37). Students reported that PEOs contributed to their persistence by enabling them to network, reduce gender and race/ethnic isolation, and access professional resources. URM students should be encouraged to participate in PEOs beginning in their first year to increase their integration in their major, which we have found to increase their persistence.

PrEP Use and PrEP Use Disclosure are Associated with Condom Use During Sex: A Multilevel Analysis of Latino MSM Egocentric Sexual Networks.

Pre-exposure prophylaxis (PrEP) is integral to HIV prevention; however, the influence of PrEP use and PrEP use disclosure on condom use is unclear among Latinx men who have sex with men (LMSM). This study explored associations of LMSM PrEP use and use disclosure on consistent dyadic condom use in the past 6 months. Participants were 130 HIV-negative PrEP and non-PrEP using LMSM ages 20-39 years. Two-level logistic regression models assessing individual- and dyadic-level predictors on condom use were fitted using R. Participants reported a mean of four sexual partners (n = 507 dyads). Participants who reported using PrEP or having more sexual partners were more likely to use condoms; however, participants who reported disclosing PrEP use were less likely to use condoms. Future longitudinal studies should characterize approaches to increase informed personal health choices and conversations about PrEP, condom use, and other HIV risk-reduction strategies using network methodologies.

RESUMEN: La pastilla PrEP es un nuevo método profiláctico para prevenir el contagio del VIH. Aun no se ha determinado la manera en que el consumo de PrEP y las conversaciones sobre el uso de PrEP puedan influenciar en el uso de condones entre los hombres Latinos que tienen relaciones sexuales con otros hombres (HLSH). Este estudio exploró las asociaciones entre el uso y la divulgación del uso de PrEP con el uso de condones durante las relaciones sexuales que los HLSH tuvieron en los últimos 6 meses. En este estudio participaron un total 130 HLSH que eran VIH-negativos usuarios. Los participantes podían ser usuarios o no usuarios de PrEP, pero todos debían tener entre 20 y 39 años. Estimamos modelos de regresión logística de dos niveles, utilizando el programa R, para identificar factores individuales y diádicos asociados con el uso de condones. Los participantes reportaron un promedio de cuatro parejas sexuales (n = 507 diadas). Encontramos que los participantes que reportaron usar PrEP o tenían un promedio mayor de parejas sexuales tenían una mayor probabilidad de haber usando condones. Sin embargo, la probabilidad de haber usados condones se redujo en los participantes que comunicaron a sus parejas sexuales que usaban PrEP. Es necesario implementar otros estudios longitudinales para entender como diseñar estrategias basadas en redes sociales que promuevan conversaciones sobre PrEP y el uso de condones.

Innovative teaching knowledge stays with users.

Programs seeking to transform undergraduate science, technology, engineering, and mathematics courses often strive for participating faculty to share their knowledge of innovative teaching practices with other faculty in their home departments. Here, we provide interview, survey, and social network analyses revealing that faculty who use innovative teaching practices preferentially talk to each other, suggesting that greater steps are needed for information about innovative practices to reach faculty more broadly.

Research and Practice Communications Between Oral Health Providers and Prenatal Health Providers: A Bibliometric Analysis.

Objectives We aimed to examine scholarly collaboration between oral health and prenatal providers. Oral disease is a silent epidemic with significant public health implications for pregnant women. Evidence linking poor oral health during pregnancy to adverse pregnancy and birth outcomes requires oral health and prenatal providers to communicate on the prevention, treatment and co-management matters pertaining to oral health issues among their pregnant patients. The need for inter-professional collaboration is highlighted by guidelines co-endorsed by the American College of Obstetricians and Gynecologists and the American Dental Association, stressing the importance of oral health care during pregnancy. Methods To assess if interdisciplinary communication occurs between oral health and prenatal disciplines, we conducted a network analysis of research on pregnancy-related periodontal disease. Results Social Network analysis allowed us to identify communication patterns between communities of oral health and prenatal professionals via scientific journals. Analysis of networks of citations linking journals in different fields reveals a core-periphery pattern dominated by oral health journals with some participation from medicine journals. However, an analysis of dyadic ties of citation reveals statistically significant "inbreeding" tendencies in the citation patterns: both medical and oral health journals tend to cite their own kind at greater-than-chance levels. Conclusions Despite evidence suggesting that professional collaboration benefits patients' overall health, findings from this research imply that little collaboration occurs between these two professional groups. More collaboration may be useful in addressing women's oral-systemic health concerns that result in adverse pregnancy outcomes.

Bearing the burden: deployment stress among army national guard chaplains.

Military Chaplains are a critical component of behavioral health and spiritual support in combat operations. Support of combat operations has taken a toll on these caregivers. The purpose of this study was to explore the impact of deployment on the psychosocial and health characteristics and reintegration of Army National Guard (ARNG) chaplains. Seventy-four ARNG chaplains participated in an anonymous, online survey. Results were categorized into two mutually exclusive groups, combat deployed and non-combat deployed. Although both groups tended to present similar results, Combat deployed group chaplains were significantly more likely to be of higher rank, have served in a pastoral role in the ARNG longer, and present with higher scores for combat exposure, resilience, and alcohol use. Further, five and seven participants, respectively, the majority of whom were from the combat deployed group, endorsed "frequently" or "a great deal" to negative religious coping. These endorsements of abandonment may relate back to Reserve component specific deployment concerns.

A social network analysis of treatment discoveries in cancer.

Controlled clinical trials are widely considered to be the vehicle to treatment discovery in cancer that leads to significant improvements in health outcomes including an increase in life expectancy. We have previously shown that the pattern of therapeutic discovery in randomized controlled trials (RCTs) can be described by a power law distribution. However, the mechanism generating this pattern is unknown. Here, we propose an explanation in terms of the social relations between researchers in RCTs. We use social network analysis to study the impact of interactions between RCTs on treatment success. Our dataset consists of 280 phase III RCTs conducted by the NCI from 1955 to 2006. The RCT networks are formed through trial interactions formed i) at random, ii) based on common characteristics, or iii) based on treatment success. We analyze treatment success in terms of survival hazard ratio as a function of the network structures. Our results show that the discovery process displays power law if there are preferential interactions between trials that may stem from researchers' tendency to interact selectively with established and successful peers. Furthermore, the RCT networks are "small worlds": trials are connected through a small number of ties, yet there is much clustering among subsets of trials. We also find that treatment success (improved survival) is proportional to the network centrality measures of closeness and betweenness. Negative correlation exists between survival and the extent to which trials operate within a limited scope of information. Finally, the trials testing curative treatments in solid tumors showed the highest centrality and the most influential group was the ECOG. We conclude that the chances of discovering life-saving treatments are directly related to the richness of social interactions between researchers inherent in a preferential interaction model.