Effects of sterile insect releases on a population under predation or parasitism

Summary A continuous-time differential equation model was constructed which describes the population dynamics of a predator prey system in which sterile prey are released in a program designed to eradicate or reduce the prey population. It was found that the dynamics of the system behave quite differently when predators are present. Two conditions were found which have differing implications for the control program. If the predators still exist when the wild prey population declines to extinction, then the SIRM is assisted by the predators, sometimes to a considereble extent. If the predators decline to extinction before the wild prey population goes extinct, then the predators may or may not assist the SIRM depending on the parameters of the system. If the predators do assist the SIRM, then a potentially dangerous situation exists in which an explosion of the prey population could occur after the predators go extinct. Predator polyphagy would probably minimize this danger of an explosion since it would stabilize the predator population.     

Social Conflict: Implications for Casework Practice

Summary The concept of social conflict is examined in terms of its usefulnessin refining and extending social casework theory. Attentionis given to the influence of the homeostatic approach to caseworkpractice versus an approach utilizing a conflict orientation.Primary emphasis is given to Coser's sociological theory ofconflict in an effort to discover heuristic concepts which areconsidered to be applicable in the practice of social casework.Specifically, seven of Coser's original sixteen propositionsrelated to conflict theory have been selected for analysis.It is concluded that a conflict orientation would serve to clarifythe functional aspects of conflict as they relate to the dyadiccasework relationship     

Reconstructing the size of the African American population by age and sex, 1930–1990

We estimate the size of the African American population in five-year age groups at census dates from 1930 to 1990 using a three-part strategy. For cohorts born after 1935, we follow the U.S. Census Bureau in using classical demographic analysis. To estimate the size of cohorts born before 1895, we use extinct-generation estimates. For remaining cohorts, we implement an age/period/cohort model of census counts. All approaches are applied to a data set in which the age distribution of deaths has been corrected for age misreporting. Results provide strong confirmation of the basic validity of Census Bureau estimates of census undercounts for African Americans while extending estimates to new cohorts and periods. Our estimates are less consistent with an historical series prepared by Coale and Rives (1973).     

A gender comparison of HIV and drug use across the rural-urban continuum

Despite the central role of women drug users in escalating AIDS statistics, there is still a limited number of studies that examine the roles of gender and drug use type in HIV seroprevalence. This lacuna in the research literature has led to significant gaps in researchers' understanding of how and to what extent women may differ in their drug-using and HIV risk behaviors compared to their better-studied male counterparts. This study, derived from a sample of 3,555 out-of-treatment drug users residing in three South Florida urban and rural communities, attempts to compare the drug usage and needle and sexual risk behaviors of male and female drug users that put them at risk for HIV infection. The overall seropositivity rate for women drug users was 26.5% compared to 19.5% for their male counterparts. Results of multivariate analyses indicate that females compared to males were 1.4 times more likely to be HIV seropositive. Risk behaviors associated with this elevated seropositivity include living arrangements, homeless status, drug use, sexual trading behaviors, and history of STDs. Furthermore, there was a strong linear relationship between drug use type and HIV seroprevalence among women drug users. Compared to those who were neither crack smokers nor injectors of illicit drugs, those who were crack smokers only were 2 times more likely to be HIV seropositive, while those who were both crack smokers and injectors were 5 times more likely to be HIV seropositive, and those who were injectors only were 6 times more likely to be HIV seropositive. These findings indicate that among women, drug abuse and its associated risk behaviors, increase the vulnerability of this population for HIV and thus render them an extremely important priority population on which to focus HIV prevention and public health efforts and programs.     

Moving and union dissolution

This paper examines the effect of migration and residential mobility on union dissolution among married and cohabiting couples. Moving is a stressful life event, and a large, multidisciplinary literature has shown that family migration often benefits one partner (usually the man) more than the other Even so, no study to date has examined the possible impact of within-nation geographical mobility on union dissolution. We base our longitudinal analysis on retrospective event-history data from Austria. Our results show that couples who move frequently have a significantly higher risk of union dissolution, and we suggest a variety of mechanisms that may explain this.     

What types of occupations are women entering? : Determinants of changes in female representation: 1970–2000

Although a consistent body of research has demonstrated that occupational segregation is highly consequential for women's economic standing, we know little about the processes that contribute to changes in levels of sex segregation. In this study, we examine those factors that contribute to changes in the percent of women in detailed occupational categories in the United States. Since we are most concerned with the economic consequences of this type of segregation, we analyze a group of high-paying, male-dominated occupations that, if better integrated, would contribute most to earnings equality. We find that occupations to which relatively high percentages of women aspired and occupations that are growing have been experiencing above-average increases in the percentage of women, while occupations characterized by male-stereotyped task profiles have been witnessing below-average increases. Additionally, our results suggest the presence of a ceiling effect: it is easier for women to break into male-dominated occupations initially than to sustain growth. Our analysis suggests that both supply and demand-side explanations provide insight into the processes contributing to increases in the occupations that we examine, although it can be very difficult to distinguish between supply and demand-side elements; indeed they may occur simultaneously.