Only Death Will Separate Us: The Role of Extramarital Partnerships among Himba Pastoralists

Extramarital partnerships are highly stigmatized in many societies and are typically excluded from studies of family dynamics and social support. Nevertheless, in many societies such relationships are common and can have important impacts on resource security and health outcomes. However, current studies of these relationships come mainly from ethnographic studies, with quantitative data extremely rare. Here we present data from a 10-year study of romantic partnerships among a community of Himba pastoralists in Namibia, where concurrency is common. The majority of married men (97%) and women (78%) currently reported having more than one partner (n = 122). Using multilevel models comparing marital and nonmarital relationships, we found that, contrary to conventional wisdom surrounding concurrency, Himba form enduring bonds with extramarital partners that often last decades and are very similar to marital ones in terms of length, emotional affect, reliability, and future prospects. Qualitative interview data showed that extramarital relationships were imbued with a set of rights and obligations that, while distinct from those of spouses, provide an important source of support. Greater inclusion of these relationships in studies of marriage and family would provide a clearer picture of social support and resource transfers in these communities and help to explain variation in the practice and acceptance of concurrency around the world.

Sexual Concurrency Among Adolescent Women With Multiple Partners: A Daily Diary Study

PURPOSE

Sexual partnerships that overlap in some period of time (i.e., concurrent) are a key factor in sexually transmitted infection (STI) transmission. Research examining concurrency among adolescents typically uses person-level, cross-sectional, and/or retrospective data, obscuring factors that manifest on any given occasion of concurrency. We used sexual diaries to examine: (1) daily prevalence of vaginal sex concurrency when two partners are reported by adolescent women; and (2) individual, relational, and behavioral attributes that impact the likelihood of sex with neither partner, with one partner or the other, or with both partners on any given day.

METHODS

Daily diaries were drawn from a large longitudinal cohort study examining sexual relationships, behaviors, and STIs among adolescent women. Participants contributed 280,844 partner-associated diary entries, of which (27.9%; n = 78,356) indicated multiple partners. All two-partner diary entries were retained for analysis (N = 323; Mage = 17.55; 90% African American). Random intercept mixed-effects multinomial logistic regression was used to evaluate the impact of predictor variables on odds of having sex with one or the other, both, or neither partner.

RESULTS

Most two-partner days (93.5%) involved no sex with either partner. Few reports (.2%) indicated same-day sexual concurrency. Older age, greater partner support, and higher sexual interest increased the likelihood of sex with both partners on the same day.

CONCLUSIONS

Individual, relational, and behavioral factors predict concurrency in ways that challenge assumptions that secondary partnerships constitute negligible relationships. Programs targeting partner concurrency in adolescents may find success tailoring messaging around these findings.

Sexual partnership concurrency and age disparities associated with sexually transmitted infection and risk behavior in rural communities in Kenya and Uganda

OBJECTIVES

We examined sex-specific associations of partner age disparity and relationship concurrency with Neisseria gonorrhoeae and/or Chlamydia trachomatis (NG/CT) infection, higher-risk relationships, and condom use as proxies for HIV risk.

METHODS

Data were collected in 2016 from 2179 adults in 12 communities in Uganda and Kenya. Logistic regression models examined associations of age disparity and relationship concurrency with NG/CT infection, condom use, and higher-risk (commercial sex and other higher-risk) relationships in the past 6 months, controlling for covariates.

RESULTS

Partner age and relationship concurrency were associated with NG/CT infection in women but not men. Relative to women in age-disparate relationships, women in both age-disparate and age-homogeneous relationships had higher odds of NG/CT infection (adjusted odds ratio [aOR]=3.82, 95% confidence interval [CI]: 1.46-9.98). Among men and women, partnership concurrency was associated with higher-risk partnerships. In addition, relative to those with a single age-homogeneous partner, those with concurrent age-homogeneous partners had higher odds of condom use (men: aOR=2.85, 95% CI: 1.89-4.31; women: aOR=2.99, 95% CI: 1.52-5.89). Concurrent age-disparate partnerships were associated with condom use among men only (aOR=4.02, 95% CI: 2.54-6.37).

CONCLUSION

Findings underscore the importance of targeted HIV prevention efforts for couples in age-disparate and concurrent relationships.

FCLQC: fast and concurrent lossless quality scores compressor

BACKGROUND

Advances in sequencing technology have drastically reduced sequencing costs. As a result, the amount of sequencing data increases explosively. Since FASTQ files (standard sequencing data formats) are huge, there is a need for efficient compression of FASTQ files, especially quality scores. Several quality scores compression algorithms are recently proposed, mainly focused on lossy compression to boost the compression rate further. However, for clinical applications and archiving purposes, lossy compression cannot replace lossless compression. One of the main challenges for lossless compression is time complexity, where it takes thousands of seconds to compress a 1 GB file. Also, there are desired features for compression algorithms, such as random access. Therefore, there is a need for a fast lossless compressor with a reasonable compression rate and random access functionality.

RESULTS

This paper proposes a Fast and Concurrent Lossless Quality scores Compressor (FCLQC) that supports random access and achieves a lower running time based on concurrent programming. Experimental results reveal that FCLQC is significantly faster than the baseline compressors on compression and decompression at the expense of compression ratio. Compared to LCQS (baseline quality score compression algorithm), FCLQC shows at least 31x compression speed improvement in all settings, where a performance degradation in compression ratio is up to 13.58% (8.26% on average). Compared to general-purpose compressors (such as 7-zip), FCLQC shows 3x faster compression speed while having better compression ratios, at least 2.08% (4.69% on average). Moreover, the speed of random access decompression also outperforms the others. The concurrency of FCLQC is implemented using Rust; the performance gain increases near-linearly with the number of threads.

CONCLUSION

The superiority of compression and decompression speed makes FCLQC a practical lossless quality score compressor candidate for speed-sensitive applications of DNA sequencing data. FCLQC is available at https://github.com/Minhyeok01/FCLQC and is freely available for non-commercial usage.

The Impact of Relationship Stressors on Trust and Prorelationship Behavior Within Adolescent Romantic Relationships: A Systems Approach

PURPOSE

Trust is an essential component of romantic relationships. It is not understood how youth respond to a relationship stressor, which may impact trust, such as perceiving to be at risk for a sexually transmitted infection or their partner has other sex partners. We used a system science approach to examine feedback between trust and prorelationship behaviors within adolescent relationships.

METHODS

A prospective cohort of clinic-recruited young women (N = 122), aged 16-19 years, completed daily questionnaires on partner-specific feelings and risk perceptions for 18 months. Relationship stressor defined as either perceiving the risk of sexually transmitted infection from a partner or partner had other sex partners. Prorelationship behaviors were more time spent with partner, sex with partner, and/or gift from partner. Time-lagged generalized estimating equation models were used to examine whether a relationship stressor is associated with a decrease in trust and whether prorelationship behaviors changed following the stressor.

RESULTS

Experiencing a stressor was associated with threefold increased odds of having a decrease in trust in the same week (odds ratio [OR] = 3.30, 95% confidence interval [CI]: 2.30-4.72). Trust increased significantly the week following the stressor (OR = 2.09, 95% CI: 1.54-2.85). An increase in trust relative to the week of the stressor was associated with a 65% increase in prorelationship behavior in the week following the stressor (OR = 1.65, 95% CI: 1.20-2.26).

CONCLUSIONS

Data uniquely show that trust is impacted following a relationship stressor and that youth increase prorelationship behaviors following a drop in trust. The findings suggest that adolescents prioritize maintaining trust, which may impact engagement in protective health behaviors.

Impact of concurrency on the performance of a whole exome sequencing pipeline

Background

Current high-throughput technologies—i.e. whole genome sequencing, RNA-Seq, ChIP-Seq, etc.—generate huge amounts of data and their usage gets more widespread with each passing year. Complex analysis pipelines involving several computationally-intensive steps have to be applied on an increasing number of samples. Workflow management systems allow parallelization and a more efficient usage of computational power. Nevertheless, this mostly happens by assigning the available cores to a single or few samples’ pipeline at a time. We refer to this approach as naive parallel strategy (NPS). Here, we discuss an alternative approach, which we refer to as concurrent execution strategy (CES), which equally distributes the available processors across every sample’s pipeline.

Results

Theoretically, we show that the CES results, under loose conditions, in a substantial speedup, with an ideal gain range spanning from 1 to the number of samples. Also, we observe that the CES yields even faster executions since parallelly computable tasks scale sub-linearly. Practically, we tested both strategies on a whole exome sequencing pipeline applied to three publicly available matched tumour-normal sample pairs of gastrointestinal stromal tumour. The CES achieved speedups in latency up to 2–2.4 compared to the NPS.

Conclusions

Our results hint that if resources distribution is further tailored to fit specific situations, an even greater gain in performance of multiple samples pipelines execution could be achieved. For this to be feasible, a benchmarking of the tools included in the pipeline would be necessary. It is our opinion these benchmarks should be consistently performed by the tools’ developers. Finally, these results suggest that concurrent strategies might also lead to energy and cost savings by making feasible the usage of low power machine clusters.

Characterizing Men Who Have Sex with Transgender Women in Lima, Peru: Sexual Behavior and Partnership Profiles

HIV prevalence is high among transgender women (TW), but how HIV is transmitted to this population is not well understood. This analysis aims to characterize sexual partners of TW (PTW) to understand how their behavior contributes to HIV risk among TW. We examined baseline data from TW, PTW, and men who have sex with men (MSM) from a treatment-as-prevention study in Lima, Peru. Individual and partnership characteristics were compared across groups, and Poisson regression was used to calculate prevalence ratios for associations between sexual concurrency and potential correlates. We found that 81% of PTW had no cisgender male partners. Prevalence of alcohol dependency, concurrency, and condomless anal intercourse was high and HIV testing was low compared to the other groups. Our results suggest that PTW are a distinct population from MSM and TW, engage in behavior associated with HIV transmission, and are likely not well reached by HIV prevention interventions.

A qualitative study of attitudes towards, typologies, and drivers of concurrent partnerships among people of black Caribbean ethnicity in England and their implications for STI prevention

BACKGROUND

Partner concurrency, (having sexual partnerships overlapping in time), especially when condoms are not used, can facilitate sexually transmitted infections (STI) transmission. In Britain, STI diagnoses rates and the reporting of concurrency are higher among black Caribbeans than other ethnic groups. We explored attitudes towards, drivers, characteristics, and contexts of concurrent partnerships, and their implications for STI risk among black Caribbeans in England.

METHODS

Purposive sampling, by sex and age-groups, was used to recruit participants (overall n = 59) from five sexual health clinics and community settings in London and Birmingham, England. Audio-recorded four focus group discussions (n = 28 participants), and in-depth interviews (n = 31) were conducted (June 2014-December 2015). Transcribed data were thematically analysed using Framework Analysis.

RESULTS

'Main plus' and 'non-main' concurrency were identified in this population. Main plus concurrency involves an individual having a main partner with whom s/he has a "relationship" with, and the individual and/or their partner secretly or explicitly have other non-main partners. In contrast, non-main concurrency entails having multiple, non-committed partners overlapping in time, where concurrency is usually taken as a given, making disclosure to partners irrelevant. While main partnerships were usually long-term, non-main partnerships ranged in duration from a single event through to encounters lasting several months/years. Condomless sex was common with ex/long-term/married/cohabiting partners; whereas condoms were typically used with non-main partners. However, condom use declined with partnership duration and familiarity with partners. Awareness of partners' concurrency facilitated condom use, STI-testing, and partner notification. While unresolved feelings, or sharing children with ex-partners, usually facilitated main plus concurrency; non-main concurrency was common among young, and single people. Gender norms, notions of masculinity, and sexual desires influenced concurrency. Black Caribbean popular music, social media, peer pressure, and relationship norms among black Caribbeans were also perceived to encourage concurrency, especially among men and young people.

CONCLUSIONS

Concurrency among black Caribbeans is shaped by a complex interaction between emotional/psychological, interpersonal, sociocultural, and structural factors. Concurrency type, its duration, and awareness influence sexual health choices, and thus STI risk in this population. Collecting these data during clinic consultations could facilitate offering partner notification methods tailored to concurrency type. Gender- and age-specific, culturally-sensitive interventions addressing STI risks associated with concurrency are needed.

Event-driven industrial robot control architecture for the Adept V+ platform

Modern industrial robotic systems are highly interconnected. They operate in a distributed environment and communicate with sensors, computer vision systems, mechatronic devices, and computational components. On the fundamental level, communication and coordination between all parties in such distributed system are characterized by discrete event behavior. The latter is largely attributed to the specifics of communication over the network, which, in terms, facilitates asynchronous programming and explicit event handling. In addition, on the conceptual level, events are an important building block for realizing reactivity and coordination. Event-driven architecture has manifested its effectiveness for building loosely-coupled systems based on publish-subscribe middleware, either general-purpose or robotic-oriented. Despite all the advances in middleware, industrial robots remain difficult to program in context of distributed systems, to a large extent due to the limitation of the native robot platforms. This paper proposes an architecture for flexible event-based control of industrial robots based on the Adept V+ platform. The architecture is based on the robot controller providing a TCP/IP server and a collection of robot skills, and a high-level control module deployed to a dedicated computing device. The control module possesses bidirectional communication with the robot controller and publish/subscribe messaging with external systems. It is programmed in asynchronous style using pyadept, a Python library based on Python coroutines, AsyncIO event loop and ZeroMQ middleware. The proposed solution facilitates integration of Adept robots into distributed environments and building more flexible robotic solutions with event-based logic.

EPypes: a framework for building event-driven data processing pipelines

Many data processing systems are naturally modeled as pipelines, where data flows though a network of computational procedures. This representation is particularly suitable for computer vision algorithms, which in most cases possess complex logic and a big number of parameters to tune. In addition, online vision systems, such as those in the industrial automation context, have to communicate with other distributed nodes. When developing a vision system, one normally proceeds from ad hoc experimentation and prototyping to highly structured system integration. The early stages of this continuum are characterized with the challenges of developing a feasible algorithm, while the latter deal with composing the vision function with other components in a networked environment. In between, one strives to manage the complexity of the developed system, as well as to preserve existing knowledge. To tackle these challenges, this paper presents EPypes, an architecture and Python-based software framework for developing vision algorithms in a form of computational graphs and their integration with distributed systems based on publish-subscribe communication. EPypes facilitates flexibility of algorithm prototyping, as well as provides a structured approach to managing algorithm logic and exposing the developed pipelines as a part of online systems.

Differential sexual network connectivity offers a parsimonious explanation for population-level variations in the prevalence of bacterial vaginosis: a data-driven, model-supported hypothesis

BACKGROUND

The prevalence of bacterial vaginosis (BV) and vaginal microbiota types varies dramatically between different populations around the world. Understanding what underpins these differences is important, as high-diversity microbiotas associated with BV are implicated in adverse pregnancy outcomes and enhanced susceptibility to and transmission of sexually transmitted infections.

MAIN TEXT

We hypothesize that these variations in the vaginal microbiota can, in part, be explained by variations in the connectivity of sexual networks. We argue: 1) Couple-level data suggest that BV-associated bacteria can be sexually transmitted and hence high sexual network connectivity would be expected to promote the spread of BV-associated bacteria. Epidemiological studies have found positive associations between indicators of network connectivity and the prevalence of BV; 2) The relationship between BV prevalence and STI incidence/prevalence can be parsimoniously explained by differential network connectivity; 3) Studies from other mammals are generally supportive of the association between network connectivity and high-diversity vaginal microbiota.

CONCLUSION

To test this hypothesis, we propose a combination of empirical and simulation-based study designs.

Peer norms moderate the association between mental health and sexual risk behaviors among young men living in Dar es Salaam, Tanzania

BACKGROUND

Young men living in Dar es Salaam's informal settlements face environmental stressors that may expose them to multiple determinants of HIV risk including poor mental health and risky sexual behavior norms. We aimed to understand how these co-occurring risk factors not only independently affect men's condom use and sexual partner concurrency, but also how they interact to shape these risk behaviors.

METHODS

Participants in the study were male members of 59 social groups known as "camps" in Dar es Salaam, Tanzania. We assessed moderation by changes in peer norms of the association between changes in symptoms of anxiety and depression and sexual risk behaviors (condom use and sexual partner concurrency) among 1113 sexually active men. Participants nominated their three closest friends in their camp and reported their perceptions of these friends' behaviors, attitudes, and encouragement of condom use and concurrency. Anxiety and depression were measured using the HSCL-25, and condom use and sexual partner concurrency were assessed through self-report.

RESULTS

Perceptions of decreasing condom use among friends (descriptive norms) and decreasing encouragement of condom use were associated with lower levels of condom use. Perceptions of increasing partner concurrency and acceptability of partner concurrency (injunctive norms) among friends were associated with higher odds of concurrency. Changes in perceived condom use norms (descriptive norms and encouragement) interacted with changes in anxiety symptoms in association with condom use such that the negative relationship was amplified by norms less favorable for condom use, and attenuated by more favorable norms for condom use.

CONCLUSIONS

These results provide novel evidence of the interacting effects of poor mental health and risky sexual behavior norms among a hard to reach population of marginalized young men in Dar es Salaam. Our findings provide important information for future norms-based and mental health promotion interventions targeting HIV prevention in this key population.

Sexual Partner Concurrency Among Partners Reported by MSM with Recent HIV Infection

We examined concurrency among sexual partners reported by men who have sex with men (MSM) with recent (acute or early) HIV infection in San Diego, California (2002-2015). Partners overlapping in time in the past 3 months were considered concurrent. Logistic generalized linear mixed models were used to identify factors associated with concurrency at the partner-level. 56% (388/699) of partners were concurrent to ≥1 other partner. The odds of concurrency were higher among partners >10 years younger than the participant (vs. within 10 years of age) [adjusted odds ratio (AOR) = 2.22, 95% confidence interval (CI) 1.09-4.52], longer term partners (AOR per month = 1.02, 95% CI 1.01-1.03), and partners met online (AOR = 1.56, 95% CI 0.98-2.48). Concurrency is common among partners of recently HIV-infected MSM. Tailored HIV prevention strategies for MSM with older partners, longer term partners, and partners met online may help minimize the potential impact of concurrency on HIV transmission.

Gender asymmetry in concurrent partnerships and HIV prevalence

The structure of the sexual network of a population plays an essential role in the transmission of HIV. Concurrent partnerships, i.e. partnerships that overlap in time, are important in determining this network structure. Men and women may differ in their concurrent behavior, e.g. in the case of polygyny where women are monogamous while men may have concurrent partnerships. Polygyny has been shown empirically to be negatively associated with HIV prevalence, but the epidemiological impacts of other forms of gender-asymmetric concurrency have not been formally explored. Here we investigate how gender asymmetry in concurrency, including polygyny, can affect the disease dynamics. We use a model for a dynamic network where individuals may have concurrent partners. The maximum possible number of simultaneous partnerships can differ for men and women, e.g. in the case of polygyny. We control for mean partnership duration, mean lifetime number of partners, mean degree, and sexually active lifespan. We assess the effects of gender asymmetry in concurrency on two epidemic phase quantities (R₀ and the contribution of the acute HIV stage to R₀) and on the endemic HIV prevalence. We find that gender asymmetry in concurrent partnerships is associated with lower levels of all three epidemiological quantities, especially in the polygynous case. This effect on disease transmission can be attributed to changes in network structure, where increasing asymmetry leads to decreasing network connectivity.

Influence of concurrency, partner choice, and viral suppression on racial disparity in the prevalence of HIV infected women

In 1992, Watts and May introduced a simple dynamical systems model of the spread of HIV based on disease transmission per partnership including the length of partnership duration. This model allowed for the treatment of concurrent partnerships, although it was hampered by the assumption of an important latent phase which generated a non-autonomous system. Subsequent models including concurrency have been based on networks, Monte Carlo, and stochastic simulations which lose a qualitative understanding of the effects of concurrency. We present a new autonomous deterministic model of the effect of concurrent sexual partnerships that allows for an analytical study of disease transmission. We incorporate the effect of concurrency through the newly derived force of infection term in a mathematical model of the transmission of HIV through sexual contact in a population stratified by sexual behavior and race/ethnicity. The model also includes variations in population mixing (partner choice) and non-uniform Highly Active Anti-Retroviral Treatment (HAART) leading to viral suppression. We use this mathematical model to understand the non-uniform spread of HIV in women who were infected through heterosexual contact. In addition, an analytical study shows the importance of continued condom use in virally suppressed MSM. Numerical simulations of the reproduction number as a function of concurrency, viral suppression level, and mixing show a reservoir of disease present in both heterosexual and MSM populations. Statistical analysis of parameter values show that viral suppression level, mixing and progression to AIDS without viral suppression have a strong correlation (either positive or negative) with the number of HIV positive women. Concurrency and assortative mixing are shown to be essential to reproduce infection levels in women, as reported by 2010 data from the Center for Disease Control (CDC).

From non-preemptive to preemptive scheduling using synchronization synthesis

We present a computer-aided programming approach to concurrency. The approach allows programmers to program assuming a friendly, non-preemptive scheduler, and our synthesis procedure inserts synchronization to ensure that the final program works even with a preemptive scheduler. The correctness specification is implicit, inferred from the non-preemptive behavior. Let us consider sequences of calls that the program makes to an external interface. The specification requires that any such sequence produced under a preemptive scheduler should be included in the set of sequences produced under a non-preemptive scheduler. We guarantee that our synthesis does not introduce deadlocks and that the synchronization inserted is optimal w.r.t. a given objective function. The solution is based on a finitary abstraction, an algorithm for bounded language inclusion modulo an independence relation, and generation of a set of global constraints over synchronization placements. Each model of the global constraints set corresponds to a correctness-ensuring synchronization placement. The placement that is optimal w.r.t. the given objective function is chosen as the synchronization solution. We apply the approach to device-driver programming, where the driver threads call the software interface of the device and the API provided by the operating system. Our experiments demonstrate that our synthesis method is precise and efficient. The implicit specification helped us find one concurrency bug previously missed when model-checking using an explicit, user-provided specification. We implemented objective functions for coarse-grained and fine-grained locking and observed that different synchronization placements are produced for our experiments, favoring a minimal number of synchronization operations or maximum concurrency, respectively.

Individual and Partner-Level Factors Associated with Condom Non-Use Among African American STI Clinic Attendees in the Deep South: An Event-Level Analysis

The US HIV/AIDS epidemic is concentrated in the Deep South, yet factors contributing to HIV transmission are not fully understood. We examined relationships between substance use, sexual partnership characteristics, and condom non-use in an African American sample of STI clinic attendees in Jackson, Mississippi. We assessed condom non-use at last intercourse with up to three recent sexual partners reported by participants between January and June 2011. Participant- and partner-level correlates of condom non-use were examined using generalized estimating equations. The 1295 participants reported 2880 intercourse events, of which 1490 (51.7 %) involved condom non-use. Older age, lower educational attainment, reporting financial or material dependence on a sex partner, sex with a primary partner, and higher frequency of sex were associated with increased odds of condomless sex. HIV prevention efforts in the South should address underlying socioeconomic disparities and structural determinants that result in partner dependency and sexual risk behavior.

Young Men's Social Network Characteristics and Associations with Sexual Partnership Concurrency in Tanzania

Social network influence on young people's sexual behavior is understudied in sub-Saharan Africa. Previous research identified networks of mostly young men in Dar es Salaam who socialize in "camps". This study describes network characteristics within camps and their relationship to young men's concurrent sexual partnerships. We conducted surveys with a nearly complete census of ten camp networks (490 men and 160 women). Surveys included name generators to identify camp-based networks. Fifty seven percent of sexually active men (n = 471) reported past year concurrency, measured using the UNAIDS method. In a multivariable model, men's individual concurrency was associated with being a member of a closer knit camp in which concurrency was the normative behavior. Younger men who had older members in their networks were more likely to engage in concurrency. Respondent concurrency was also associated with inequitable personal gender norms. Our findings suggest strategies for leveraging social networks for HIV prevention among young men.

Interdependent effects of cohesion and concurrency for epidemic potential

PURPOSE

Network diffusion depends on both the pattern and timing of relations, but the relative effects of timing and structure remain unclear. Here, we first show that concurrency (relations that overlap in time) increases epidemic potential by opening new routes in the network. Because this is substantively similar to adding contact paths, we next compare the effects of concurrency by observed levels of path redundancy (structural cohesion) to determine how the features interact.

METHODS

We establish that concurrency increases exposure analytically and then use simulation methods to manipulate concurrency over observed networks that vary naturally on structural cohesion. This design allows us to compare networks across a wide concurrency range holding constant features that might otherwise conflate concurrency and cohesion. We summarize the simulation results with general linear models.

RESULTS

Our results indicate interdependent effects of concurrency and structural cohesion: although both increase epidemic potential, concurrency matters most when the graph structure is sparse, because the exposure created by concurrency is redundant to observed paths within structurally cohesive networks.

CONCLUSIONS

Concurrency works by opening new paths in temporally ordered networks. Because this is substantively similar to having additional observed paths, concurrency in sparse networks has the same effect as adding relations and will have the greatest effect on epidemic potential in sparse networks.

Predictors of perceived male partner concurrency among women at risk for HIV and STI acquisition in Durban, South Africa

BACKGROUND

Women in sub-Saharan Africa continue to be at greater risk for HIV acquisition than men. Concurrency, viz. multiple sexual partnerships that overlap over time, has been studied as a possible risk factor for HIV transmission. The aim of this study was to identify predictors of perceived male partner concurrency among sexually active, HIV negative women.

METHODS

Socio-demographic and behavioural data from women enrolled in a biomedical HIV prevention clinical trial were assessed in relation to perceived male partner concurrency using the Chi squared test. Univariate and multivariate logistic regression was performed to assess the independent predictors of perceived male partner concurrency. Kaplan-Meier survival estimates were obtained for HIV and STI incidence in relation to male partner concurrency. A Cox Proportional Hazards model was used to assess the association between perceived male partner concurrency and HIV and STI incidence.

RESULTS

The results revealed that 29 % of women reported their male partners to be in concurrent sexual relationships, 22 % reported partners that were not engaging in concurrency, whilst 49 % reported not knowing their partners concurrency status. Older women, having never married, experiencing economic abuse, and women reporting individual concurrency, were found to be significant predictors of perceived male partner concurrency in the studied population. Perceived male partner concurrency was not found to be a significantly associated with incident HIV and STI infections in this analysis.

CONCLUSIONS

The study provides insight into predictors of perceived male partner concurrency among women at high risk for STI and HIV acquisition. These results may inform the design of behavioural and biomedical interventions, to address the role of multiple sexual partnerships in HIV prevention.

Attitudes Towards Power in Relationships and Sexual Concurrency Within Heterosexual Youth Partnerships in Baltimore, MD

Sexual concurrency may increase risk for HIV/STIs among youth. Attitudes about gender roles, including power balances within sexual partnerships, could be a driver. We examined this association among Baltimore youth (N = 352), aged 15-24. Data were collected from February, 2011 to May, 2013. We examined whether index concurrency in male-reported partnerships (N = 221) and sex partner's concurrency in female-reported partnerships (N = 241) were associated with youth's attitudes towards relationship power. Males with more equitable beliefs about power were less likely to report index concurrency. Females with more equitable beliefs were more likely to report sex partner's concurrency. The relationship was significant in main and casual partnerships among females and main partnerships among males. The strongest associations were detected among middle-socioeconomic status (SES) males and low-SES and African American females. Implementing interventions that recognize the complex relationship between socioeconomic context, partner dynamics, gender, and sexual behavior is an important step towards reducing HIV/STI risk among youth.

A preliminary evaluation of a community-based campaign to increase awareness of concurrency and HIV transmission in African American and African-Born communities

We evaluate an innovative grassroots community-based campaign in Seattle, WA focused on educating African American and African-born communities about concurrent partnerships and HIV transmission. Respondents completed a short self-administered questionnaire on a handheld personal digital assistant to evaluate the reach, acceptability and preliminary efficacy of the campaign. Of those who remembered seeing the campaign materials (82 %), social networks were the most common source of exposure (80 %). Respondents rated campaign materials very visually attractive (86 %), very interesting (91 %), and very important for themselves (90 %) and their community (93 %). Respondents reported that the campaign increased their knowledge about concurrency (84 %), changed their attitudes about it (77 %), and 65 % said it was likely or very likely that they would change their behavior as a result. This inexpensive grassroots campaign demonstrated extensive reach in the local black community and was able to move beyond individual exposure and into social networks.

The problem of multimodal concurrent serial order in behavior

The "problem of serial order in behavior," as formulated and discussed by Lashley (1951), is arguably more pervasive and more profound both than originally stated and than currently appreciated. We spell out two complementary aspects of what we term the generalized problem of behavior: (i) multimodality, stemming from the disparate nature of the sensorimotor variables and processes that underlie behavior, and (ii) concurrency, which reflects the parallel unfolding in time of these processes and of their asynchronous interactions. We illustrate these on a number of examples, with a special focus on language, briefly survey the computational approaches to multimodal concurrency, offer some hypotheses regarding the manner in which brains address it, and discuss some of the broader implications of these as yet unresolved issues for cognitive science.

Sampling dynamic networks with application to investigation of HIV epidemic drivers

We propose a method for randomly sampling dynamic networks that permits isolation of the impact of different network features on processes that propagate on networks. The new methods permit uniform sampling of dynamic networks in ways that ensure that they are consistent with both a given cumulative network and with specified values for constraints on the dynamic network properties. Development of such methods is challenging because modifying one network property will generally tend to modify others as well. Methods to sample constrained dynamic networks are particularly useful in the investigation of network-based interventions that target and modify specific dynamic network properties, especially in settings where the whole network is unobservable and therefore many network properties are unmeasurable. We illustrate this method by investigating the incremental impact of changes in networks properties that are relevant for the spread of infectious diseases, such as concurrency in sexual relationships. Development of the method is motivated by the challenges that arise in investigating the role of HIV epidemic drivers due to the often limited information available about contact networks. The proposed methods for randomly sampling dynamic networks facilitate investigation of the type of network data that can best contribute to an understanding of the HIV epidemic dynamics as well as of the limitations of conclusions drawn in the absence of such information. Hence, the methods are intended to aid in the design and interpretation of studies of network-based interventions.

The racial disparities in STI in the U.S.: Concurrency, STI prevalence, and heterogeneity in partner selection

Background

There is a large and persistent racial disparity in STI in the U.S. which has placed non-Hispanic-Blacks at disproportionately high risk. We tested a hypothesis that both individual-level risk factors (partner number, anal sex, condom use) and local-network features (concurrency and assortative mixing by race) combine to account for the association between race and chlamydia status.

Methods

Data from the Longitudinal Survey of Adolescent Health Wave III were used. Chlamydia status was determined using biomarkers. Individual-level risk behaviors were self-reported. Network location variables for concurrency and assortative mixing were imputed using egocentrically sample data on sexual partnerships.

Results

After controlling for demographic attributes including age, sex, marital status, education and health care access there remained a strong association between race and chlamydia status (OR = 5.23, 95% CI] 3.83–7.15], p < .001 for Non-Hispanic Blacks with Non-Hispanic Whites as the reference category). The inclusion of individual-level risk factors did not alter the association between race and chlamydia(OR = 5.23 for Non-Hispanic Blacks). The inclusion of concurrency and assortative mixing by race substantially reduced the association between race and chlamydia status (OR = 1.87, 95% CI [0.89–3.91] p > .05 for Non-Hispanic Blacks).

Strong association between the prevalence of bacterial vaginosis and male point-concurrency

OBJECTIVE

The prevalence of bacterial vaginosis (BV) differs considerably between different populations, and individual-level risk factors such as number of sex partners seem unable to explain these differences. The effect of network-level factors, such as the prevalence of partner concurrency (the proportion of sexual partnerships that overlap in time as opposed to running sequentially) on BV prevalence has not hitherto been investigated.

STUDY DESIGN

We performed linear regression to assess the relationship between the prevalence of male concurrency and prevalence of BV in each of 11 countries for which we could obtain comparable data. The data for concurrency prevalence were taken from the WHO/Global Programme on AIDS (GPA) sexual behavioural surveys. BV prevalence rates were obtained from a systematic review of the global patterning of BV.

RESULTS

We found a strong relationship between the prevalence of male concurrency and BV prevalence (Pearson's R(2)=0.57; P=0.007).

CONCLUSIONS

The findings of a strong ecological-level association between BV and partner concurrency need to be replicated and augmented with different types of studies such as multilevel prospective studies tracking the incidence of BV and associated individual, partner and network level risk factors.