Unboundedness and downward closures of higher-order pushdown automata

We show the diagonal problem for higher-order pushdown automata (HOPDA), and hence the simultaneous unboundedness problem, is decidable. From recent work by Zetzsche this means that we can construct the downward closure of the set of words accepted by a given HOPDA. This also means we can construct the downward closure of the Parikh image of a HOPDA. Both of these consequences play an important role in verifying concurrent higher-order programs expressed as HOPDA or safe higher-order recursion schemes

Analysing the Complexity of Functional Programs: Higher-Order Meets First-Order

International audienceWe show how the complexity of higher-order functional programs can be analysed automatically by applying program transformations to a defunctionalized versions of them, and feeding the result to existing tools for the complexity analysis of first-order term rewrite systems. This is done while carefully analysing complexity preservation and reflection of the employed transformations such that the complexity of the obtained term rewrite system reflects on the complexity of the initial program. Further, we describe suitable strategies for the application of the studied transformations and provide ample experimental data for assessing the viability of our method

Doing Syringe Exchange: Organizational Transformation and Volunteer Commitment

The authors examine the organizational transformation of Prevention Point, the San Francisco-based syringe exchange program. Their purposes are to explore the processes of organizational change, focus on the impact of formalization on members and organizational goals, and contextualize these in light of belonging to an underground organization. They highlight the volunteers’ motivation and commitment, and their responses to the organizational changes. Drawing on qualitative interviews with 56 service providers, conducted from 1993 to 1995, the authors document the changes in the organization and the members’ perceptions of it as it moved from an illegal, deviant group to a socially sanctioned service organization. This transition is shown to have ultimately undermined much of the basis for volunteer commitment, reinforcing the shift in responsibility from the membership to a new management structure. These findings have implications for the larger problem of maintaining volunteer engagement in volunteer work.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline

HIV Services Utilization in Los Angeles County, California

Recipients of HIV/AIDS prevention services in Los Angeles County California were surveyed in 2004 by 220 HIV prevention service provider staff from 51 agencies funded by the Office of AIDS Programs and Policy. This resulted in 2,102 usable surveys for cluster analysis purposes. This Countywide Risk Assessment Survey assessed demographics, sexual history, substance use, perceptions regarding HIV/AIDS, and use of 18 different services at both the agency administering the survey and at other agencies. The 36 types of service use data were subjected to a cluster analysis that found five clusters. These service pattern clusters differed from each other on proportion HIV positive, HIV testing history, history of abuse, education, type of residence, type of funding, intervention type, and ethnicity. The analysis also suggests that domestic violence services availability and utilization should be examined more thoroughly in the future for HIV infected/affected populations

Hepatitis Vaccination of Men Who Have Sex with Men at Gay Pride Events

Prevention researchers have advocated primary prevention such as vaccination in alternative venues. However, there have been major questions about both the attendance of, and the ability to, vaccinate high-risk individuals in such settings. The current study seeks to assess the feasibility of vaccinating high-risk men who have sex with men (MSM) at Gay Pride events. The research questions are: Do gay men who are sampled at Gay Pride events engage in more or less risky behavior than gay men sampled at other venues? Do the gay men who receive hepatitis vaccinations at Gay Pride engage in more or less risky behavior than gay men at Gay Pride who do not receive hepatitis vaccination? Of the 3689 MSM that completed the Field Risk Assessment (FRA), 1095/3689 = 29.68% were recruited at either the 2006 or 2007 Long Beach, California Gay Pride events. The remaining, 2594/3689 = 70.32% were recruited at Long Beach gay bars, gay community organizations and institutions, and through street recruitment in various gay enclaves in the Long Beach area. Logistic regression analysis yielded eight factors that were associated with non-attendance of Gay Pride: Age, had sex while high in the last 12 months, had unprotected anal intercourse (UAI) in the last 12 months, had sex for drugs/money in the last 12 months, been diagnosed with a sexually transmitted infection (STI) in the last 12 months, used nitrites (poppers) in the last 12 months, and used methamphetamine in the last 12 months. Identifying as White, Asian, or African American compared to Hispanic was also associated with non-attendance. Bivariate analysis indicated that, of the MSM sampled at Gay Pride, 280/1095 = 25.57% received a hepatitis vaccination there. The MSM sampled at Gay Pride who reported engaging in UAI or having used any stimulant (cocaine, crack-cocaine, or methamphetamine) in the last 12 months were more likely to receive hepatitis vaccination on-site. The results provide evidence for the viability of successfully vaccinating high-risk MSM at Gay Pride events. However, it is vital that no-cost vaccinations are also funded in other community settings such as STI clinics, drug treatment programs, prisons, universities, and other community resource centers in order to reach those additional high-risk MSM who do not attend Gay Pride

Drug-Using Men Who Have Sex With Men: Sexual Behaviours and Sexual Identities

Men who have sex with men (MSM) and use drugs are at high risk for H V. This study assessed drug and sex-related risk behaviours and sexual identities for MSMIdrug injectors and crack smokers. One hundred and forty four MSM drug injectors and crack smokers from five USA cities were interviewed. One-third of the men were current injectors, twice as many reported lifetime injection. Most (56%) reported sex with women in the prior year; sex trading was reported by 32% with males and 53% with females. There were significant differences between private and public sexual identities. For example, while 31% reported being behaviourally bisexual, only 17% identified themselves to others as bisexual. Drug using MSM are clearly a heterogeneous group and prevention messages addressing this diversity are needed

Understanding HIV Risks of Chronic Drug-Using Men Who Have Sex with Men

Focus groups and individual structured interviews were conducted in six cities with 98 predominantly street-recruited men who had a recent history of smoking crack or injecting drugs and who reported having had sex with other men (MSM) in the past year. Twenty-six focus groups explored the cultural and social context of participant\u27s drug use and sexual activity and addressed outreach and HIV prevention issues pertinent to this population. Narrative summaries developed from verbatim focus group transcripts identified seven themes: (a) sexual orientation and gender identity; (b) interactions within and between MSM networks; (c) drug use, sexual activity and personal relationships; (d) HIV transmission bridges; (e) preferred HIV information sources; (f) HIV knowledge, prevention practices and risk behaviours; and (g) availability of HIV and drug-related services. Of the 98 MSM drug users, 42% identified publicly as gay or homosexual; 35% identified publicly, but only 21% privately, as heterosexual. A total of 51% had one or more female sex partners in the past year. There was a high frequency of unprotected sex in conjunction with drug use and a distinct preference for having sex when high. For most participants, drug use rather than sexual orientation formed the core of personal identity. Participants reported associating primarily with other drug users, usually MSM, and had limited contact with people who did not use drugs and the mainstream gay community. Participants\u27 sexual and drug-injecting activities were judged to be a bridge for transmission of HIV to both people who used drugs and those who did not

Drug-Using Men Who Have Sex With Men: Sexual Behaviours and Sexual Identities

Men who have sex with men (MSM) and use drugs are at high risk for H V. This study assessed drug and sex-related risk behaviours and sexual identities for MSMIdrug injectors and crack smokers. One hundred and forty four MSM drug injectors and crack smokers from five USA cities were interviewed. One-third of the men were current injectors, twice as many reported lifetime injection. Most (56%) reported sex with women in the prior year; sex trading was reported by 32% with males and 53% with females. There were significant differences between private and public sexual identities. For example, while 31% reported being behaviourally bisexual, only 17% identified themselves to others as bisexual. Drug using MSM are clearly a heterogeneous group and prevention messages addressing this diversity are needed