Virtual Machine Support for Many-Core Architectures: Decoupling Abstract from Concrete Concurrency Models

The upcoming many-core architectures require software developers to exploit concurrency to utilize available computational power. Today's high-level language virtual machines (VMs), which are a cornerstone of software development, do not provide sufficient abstraction for concurrency concepts. We analyze concrete and abstract concurrency models and identify the challenges they impose for VMs. To provide sufficient concurrency support in VMs, we propose to integrate concurrency operations into VM instruction sets. Since there will always be VMs optimized for special purposes, our goal is to develop a methodology to design instruction sets with concurrency support. Therefore, we also propose a list of trade-offs that have to be investigated to advise the design of such instruction sets. As a first experiment, we implemented one instruction set extension for shared memory and one for non-shared memory concurrency. From our experimental results, we derived a list of requirements for a full-grown experimental environment for further research

A Concurrency-Agnostic Protocol for Multi-Paradigm Concurrent Debugging Tools

Today's complex software systems combine high-level concurrency models. Each model is used to solve a specific set of problems. Unfortunately, debuggers support only the low-level notions of threads and shared memory, forcing developers to reason about these notions instead of the high-level concurrency models they chose. This paper proposes a concurrency-agnostic debugger protocol that decouples the debugger from the concurrency models employed by the target application. As a result, the underlying language runtime can define custom breakpoints, stepping operations, and execution events for each concurrency model it supports, and a debugger can expose them without having to be specifically adapted. We evaluated the generality of the protocol by applying it to SOMns, a Newspeak implementation, which supports a diversity of concurrency models including communicating sequential processes, communicating event loops, threads and locks, fork/join parallelism, and software transactional memory. We implemented 21 breakpoints and 20 stepping operations for these concurrency models. For none of these, the debugger needed to be changed. Furthermore, we visualize all concurrent interactions independently of a specific concurrency model. To show that tooling for a specific concurrency model is possible, we visualize actor turns and message sends separately.Comment: International Symposium on Dynamic Language

FLORIDA\u27S DOWNTOWNS: THE KEY TO SMART GROWTH, URBAN REVITALIZATION, AND GREEN SPACE PRESERVATION

This article reviews Florida\u27s growth management system, which has spurred suburban development, and its negative impact on Florida\u27s cities. As Florida\u27s governor and legislature have turned their focus to this issue, this article evaluates policy recommendations to limit Florida\u27s suburban sprawl and invigorate its urban centers

A Study of Concurrency Bugs and Advanced Development Support for Actor-based Programs

The actor model is an attractive foundation for developing concurrent applications because actors are isolated concurrent entities that communicate through asynchronous messages and do not share state. Thereby, they avoid concurrency bugs such as data races, but are not immune to concurrency bugs in general. This study taxonomizes concurrency bugs in actor-based programs reported in literature. Furthermore, it analyzes the bugs to identify the patterns causing them as well as their observable behavior. Based on this taxonomy, we further analyze the literature and find that current approaches to static analysis and testing focus on communication deadlocks and message protocol violations. However, they do not provide solutions to identify livelocks and behavioral deadlocks. The insights obtained in this study can be used to improve debugging support for actor-based programs with new debugging techniques to identify the root cause of complex concurrency bugs.Comment: - Submitted for review - Removed section 6 "Research Roadmap for Debuggers", its content was summarized in the Future Work section - Added references for section 1, section 3, section 4.3 and section 5.1 - Updated citation

I Want Your Sext: Sexting And Sexual Risk In Young Men

Purpose: Sexting, the act of sending or receiving sexually suggestive or explicit messages, photos or videos via mobile phone, and sexual risk have not been studied extensively within a young adult population. The overall aim of this study is to understand the predictors associated with sexting within a low-income, minority, emerging adult, male population and asses the association between sexting behaviors and sexual risk. Methods: 119, male, heterosexual, young adults participated in a longitudinal study of social networks, health behavior and health outcomes, which included a questionnaire on sexting behaviors and sexual health outcomes. This study is based on the baseline data from this longitudinal study. Results: Exposure to sexual stimuli was a predictor for most sexting behaviors but there were differences between those who sent/received to steady partners and those who sent/received to hookups. Those who sent sexts to a steady partner were less likely to use condoms over the past six months. Those who sent a sext to a hookup were 4.59 times more likely to have had concurrent relationships over their lifetime. Conclusions: The study found that sexting is a reciprocal behavior within young adult relationships. The main predictors of sexting and sexual risk outcomes vary depending on whether the sext is sent or received and to whom. The study shows that sexting is marginally related to sexual risk

Drivers of male perpetration of family and intimate partner violence in Cape Town

This paper examines the drivers of male perpetration of violence against adult family members and intimate partners in Cape Town, South Africa. Data on 1,369 young men from the Cape Area Panel Study are analyzed and significant causal pathways are examined for the full sample and for disaggregated samples of African and coloured respondents. Socioeconomic disadvantage plays a role in a culture of patriarchal violence, but its effects are largely mediated by behavioral factors such as routine alcohol consumption and having concurrent sexual partners, and norms of acceptance of violence against women. Different factors emerge as predictors of violence in the African and coloured samples. The findings of the quantitative analysis are illustrated with evidence from 45 qualitative interviews that address the role of violence in family and gender relations in Cape Town. Economic interventions are of uncertain efficacy give South Africa's difficulties since the end of apartheid in improving economic opportunities for the poor; thus interventions targeting norms and behavior hold the most promise for reducing family and intimate partner violence in the near term

Similarities and Differences in Sexual Risk Behaviors Between Young Black MSM Who Do and Do Not Have Sex with Females

The objective of this study is to determine whether young Black MSM who also have sex with females report similar levels of sexual risk behaviors as those not having sex with females. YBMSM (N = 400) were recruited from an STI clinic, located in the Southern U.S. Men completed an audio-computer assisted self-interview and donated specimens for STI/HIV testing. Forty-three percent recently engaged in penile-vaginal sex. They were less likely to report having concurrent partners (P = .01), unprotected fellatio (P = .04), multiple partners as a bottom (P \u3c .02), any unprotected anal sex as a bottom (P \u3c .013), and any anal sex (P = .007). They were equally likely to report favorable attitudes toward serosorting (P = .80), multiple male partners as a top (P = .20), unprotected anal insertive sex with males (P = .15). Frequency of sex with males as a top (P = .61) or bottom (P = .61) did not differ. Compared to YBMSM not having sex with females, those having sex with females may be exercising greater caution

A Framework for Incorporating Dyads in Models of HIV-Prevention

Although HIV is contracted by individuals, it is typically transmitted in dyads. Most efforts to promote safer sex practices, however, focus exclusively on individuals. The goal of this paper is to provide a theoretical framework that specifies how models of dyadic processes and relationships can inform models of HIV-prevention. At the center of the framework is the proposition that safer sex between two people requires a dyadic capacity for successful coordination. According to this framework, relational, individual, and structural variables that affect the enactment of safer sex do so through their direct and indirect effects on that dyadic capacity. This dyadic perspective does not require an ongoing relationship between two individuals; rather, it offers a way of distinguishing between dyads along a continuum from anonymous strangers (with minimal coordination of behavior) to long-term partners (with much greater coordination). Acknowledging the dyadic context of HIV-prevention offers new targets for interventions and suggests new approaches to tailoring interventions to specific populations