Age Is But a Number? An Exploration of Age Differences in Episodic Volunteering

VOLUNTAS: International Journal of Voluntary and Nonprofit Organizations - Age has long been understood as a strong demographic determinant of volunteering. However, to date, limited literature...     

Art in Social Movements: Shantytown Women's Protest in Pinochet's Chile

How social movements use art is an understudied question in the social movements literature. Ethnographic research on the use of art by the prodemocracy movement in Pinochet's Chile suggests that art plays a very important role in social movements, which use it for framing, to attract resources, to communicate information about themselves, to foster useful emotions, and as a symbol (for communicating a coherent identity, marking membership, and cementing commitment to the movement).     

Finite mixture models with concomitant information: assessing diagnostic criteria for diabetes

The World Health Organization (WHO) diagnostic criteria for diabetes mellitus were determined in part by evidence that in some populations the plasma glucose level 2 h after an oral glucose load is a mixture of two distinct distributions. We present a finite mixture model that allows the two component densities to be generalized linear models and the mixture probability to be a logistic regression model. The model allows us to estimate the prevalence of diabetes and sensitivity and specificity of the diagnostic criteria as a function of covariates and to estimate them in the absence of an external standard. Sensitivity is the probability that a test indicates disease conditionally on disease being present. Specificity is the probability that a test indicates no disease conditionally on no disease being present. We obtained maximum likelihood estimates via the EM algorithm and derived the standard errors from the information matrix and by the bootstrap. In the application to data from the diabetes in Egypt project a two-component mixture model fits well and the two components are interpreted as normal and diabetes. The means and variances are similar to results found in other populations. The minimum misclassification cutpoints decrease with age, are lower in urban areas and are higher in rural areas than the 200 mg dl^-1 cutpoint recommended by the WHO. These differences are modest and our results generally support the WHO criterion. Our methods allow the direct inclusion of concomitant data whereas past analyses were based on partitioning the data.     

Snake parasitism in an urban old-growth forest

Urban-associated changes can have immediate or long-term consequences on animal populations. Such changes may be assessed through parasite prevalence and abundance in wildlife hosts, as urbanization can influence parasitism and disease transmission in wildlife. Snakes are widespread and diverse vertebrates that often persist in urban environments; however, parasitism of snakes in urban environments has yet to be studied, leaving the roles of snakes in parasite transmission uncharacterized. Field ecology, microscopy, molecular techniques, and geographic information science (GIS) were integrated to characterize parasitism of snakes in an urban old-growth forest park. The species, sex, mass, length, location, and prevalence of ecto-, hemo-, and fecal parasites were determined for 34 snakes of 6 species. Ectoparasites (mite), hemoparasites (Hepatozoon spp.), and fecal parasites (Entamoeba spp., Trichomonas spp., Strongloides spp., and an unidentified helminth) were detected in snakes and 64.7?% of snakes were infected by at least one of these parasites. Parasite infections were generally not related to the sex, age, or body condition of snakes. The locations of infected snakes were used to produce risk maps indicating where parasite prevalence is predicted to be greatest. The analysis of these maps indicated that snakes with fecal parasites were closer than non-infected snakes to the edge of the forest. This study confirms that snakes may be important parasite hosts or reservoirs in parasite transmission pathways in urban environments and it provides an integrative multidisciplinary approach that may be used to monitor parasitism dynamics in other urban wildlife areas.     

Social Psychological Processes that Facilitate Sexual Assault within the Fraternity Party Subculture

Rape on the college campus has gained increasing amounts of attention in higher education, mainstream news, and public policy. The prevalence rates of rape are especially high among students who frequent campus parties, such as those hosted by fraternities. Researchers have described this increased risk by focusing on individual attitudes and behaviors of fraternity members or on the organizational norms and practices within the fraternity party subculture. To incorporate these studies into a single theoretical framework, this essay uses a social psychological approach to connect individual‐level attitudes, (sub)culture, and behavior. I describe and apply identity theory and affect control theory, two structural symbolic interactionist theories, to explain why certain men are drawn to high‐risk fraternities and how membership reinforces hostility toward and abuse of women. In doing so, I suggest several avenues for future research that would increase social psychological understanding of the heightened prevalence of sexual victimization within the fraternity party subculture.