Influence of human population size and the built environment on avian assemblages in urban green spaces

While studies of how habitat patch dynamics structures avian communities in urban environments has received some attention, there is considerably less known of how the built environment and human population size may influence the structuring of urban bird communities. We investigated bird populations in Pittsburgh, Pennsylvania (U.S.A.) through replicated point count surveys of breeding birds in 50 parks and cemeteries of varying sizes. We counted 4,435 individual birds in 441 counts. Of the 61 species detected, 27 were rare (detected at <8 points). Migratory species accounted for 46.1 % of all individuals, while 23.2 % of all individuals were of introduced species. Species richness increased significantly with green area size, as did the number of rare species. Species diversity decreased significantly with an increase in the proportion of individuals of introduced species; in particular, cavity nesters were less abundant when introduced species were present. Elements of the built urban environment including commercial development and transportation corridors were associated with significant reductions in park-wide species richness, mean number of species per point, and mean number of individual birds recorded per point. Human population size was positively related to increased numbers of individuals of introduced species, but a lower mean number of species per point. Ours is among the first to identify specific relationships between avian population characteristics and human population size, as few other studies have specifically incorporated human population size into a local, fine grain study design. Our data suggest that human population size is an important parameter that can be measured independently of characteristics of the built environment and the physical characteristics of the park itself as a correlate of avian diversity and abundance. Our study points to a variety of trade-offs needed to manage habitat for birds in urban settings.     

Family Structure and Educational Attainment: Sex Differences among Urban Blacks

Abstract

This research evaluates the impact of family structure on the educational attainment of northern urban blacks. Separate analyses of male and female adults reveal little support for the traditional view that the “broken home” lowers the achievement of black males. Rather, we find it is black females, especially in segregated contexts, who have been most adversely affected by parental absence. These findings are interpreted as reflecting the different relationship of males and females to the family under conditions of structurally-induced poverty.     

Simultaneous inference of a misclassified outcome and competing risks failure time data

Ipsilateral breast tumor relapse (IBTR) often occurs in breast cancer patients after their breast conservation therapy. The IBTR status' classification (true local recurrence versus new ipsilateral primary tumor) is subject to error and there is no widely accepted gold standard. Time to IBTR is likely informative for IBTR classification because new primary tumor tends to have a longer mean time to IBTR and is associated with improved survival as compared with the true local recurrence tumor. Moreover, some patients may die from breast cancer or other causes in a competing risk scenario during the follow-up period. Because the time to death can be correlated to the unobserved true IBTR status and time to IBTR (if relapse occurs), this terminal mechanism is non-ignorable. In this paper, we propose a unified framework that addresses these issues simultaneously by modeling the misclassified binary outcome without a gold standard and the correlated time to IBTR, subject to dependent competing terminal events. We evaluate the proposed framework by a simulation study and apply it to a real data set consisting of 4477 breast cancer patients. The adaptive Gaussian quadrature tools in SAS procedure NLMIXED can be conveniently used to fit the proposed model. We expect to see broad applications of our model in other studies with a similar data structure.     

Beyond Race/Ethnicity: Skin Color,Gender, and the Health of Young Adults in the United States

Population Research and Policy Review - Researchers typically identify health disparities using self-reported race/ethnicity, a measure identifying individuals’ social and cultural...     

Two Decades of Stability and Change in Age at First Union Formation

The landscape of union formation has been shifting; Americans are now marrying at the highest ages on record and the majority of young adults have cohabited. Yet little attention has been paid to the timing of cohabitation relative to marriage. Using the National Survey of Families and Households and 4 cycles of the National Survey of Family Growth, the authors examined the timing of marriage, cohabitation, and unions over 20 years. As the median age at first marriage has climbed, the age at cohabitation has remained stable for men and women. The changes in the timing of union formation have been similar according to race/ethnicity. The marked delay in marriage among women and men with low educational attainment has resulted in a near‐convergence in the age at first marriage according to education. The authors conclude that the rise in cohabitation has offset changes in the levels and timing of marriage     

‘Now,We Have the Same Rights as Men to Keep Our Jobs’: Gendered Perceptions of Opportunity and Obstacles in a Mexican Workplace

Drawing on extensive qualitative data at a Mexican‐owned multinational corporation, this case study investigates professional employees’ perceptions of changes to a prohibitive work policy requiring women to quit working upon marriage and having children. Employees believed the policy change meant working women were valued employees, but how this translated into opportunity highlighted distinct views of the types of positions professional women could occupy at the company, reinforcing sex‐segregated job allocation. Whereas women's narratives pointed to cultural resistance, men's narratives attributed the dearth of women in higher level positions to their lack of professionalism and commitment to work. The work policy change only guaranteed the right for women to work as the company modernized to fit the neoliberal demands of the global marketplace. Now women faced the challenge of turning that right into career advancement in a traditionally masculine‐defined company. I argue that even with the policy change, gendered discourses on women in professional occupations constructed and maintained gender inequities in the workplace. This study contributes to the scholarly discussion on gendered discourses within the context of global restructuring by showing how mechanisms at work maintain gender inequity in the workplace.