Patterns of positivity: Positive affect trajectories among infants of mothers with a history of depression

This study examined positive affect (PA) trajectories over the first year of life among infants of mothers with a history of depression (N = 191) as well as predictors (i.e., maternal prenatal and postpartum depression symptoms, maternal parenting behaviors) of those trajectories. Infant PA was observed in play and feeding tasks during laboratory visits at 3, 6, and 12 months of age; parenting behaviors were observed at 3 months. Mothers completed questionnaires regarding their symptoms of depression throughout the prenatal period and during the first 3 months postpartum. Growth curve analyses indicated that infant PA increased across time, and this finding replicated across both the play and feeding tasks, though increases slowed over time. Neither maternal prenatal nor postpartum depression symptoms predicted infants' PA trajectories, but mothers' PA, positive parenting, and disengaged parenting were associated with infant PA during the play task. Our finding that infant PA increased over the first year postpartum suggests PA trajectories among infants of mothers with a history of depression may be indices of resilience, despite risks associated with their mothers' history of depression. Furthermore, this study highlights parenting behaviors that may be important targets of prevention and early intervention efforts to bolster infant PA.     

Buildings as Artifacts: What Are Buildings in World History Telling Us?

Learning about people from long ago and far away poses a challenge for students because such people seem so distant and different. The lack of easily comprehensible text-based primary sources compounds this problem. Using a built environment as a primary source makes people from the distant past more accessible, concrete and exciting. Broadly speaking, a built environment entails all the changes that people have made to a landscape, such as buildings, roads, ways of conveying power and water, and even adaptations of the physical environment such as gardens and parks. Students' exploration of a built environment fosters historical inquiry and visual literacy, provides evidence for constructing a historical narrative, and offers insight into a people, place and time as they investigate not simply the structure, but the perspectives of those associated with it and the cultural and historical context in which it is situated. In this article we draw on our experience with 6th and 9th grade students as we present a guide on how to integrate the built environment as a source of artifacts into world history.     

The effects of urbanization on body size of larval stream salamanders

Animal body sizes in urban areas often differ from nearby rural areas, which may impact population fitness and dynamics. We examined the effects of urbanization on larval body sizes of two species of salamanders, the two-lined salamander (Eurycea cirrigera) and the northern dusky salamander (Desmognathus fuscus). Specifically, we utilized a before-after control-impact (BACI) study design which allowed for the assessment of differences in larval body size between multiple control and impacted sites over a 5 year period. We found a decrease in larval body size in both species at the impacted sites compared to control sites in the first year after urbanization, followed by generally larger body sizes in urban sites compared to control sites in years 3–5, and significantly so in year 4. Using generalized linear models, we found support that larger body sizes post impact in urbanized streams may be due to warmer stream water temperature and decreased abundance of larvae. Both E. cirrigera and D. fuscus are well known for their ability to persist in urbanized streams; our data suggest that despite overall lower abundances in urban streams, persistence may be due to increases in larval body size and, potentially, post-metamorphic benefits.     

Of Population and False Hopes: Malthus and His Legacy

Population and Environment -     

Planning for the American Dream: The College-Savings Behavior of Asian and Latino Foreign-Born Parents in the United States

Population Research and Policy Review - Rapid growth in the population of children of immigrants has occurred during an era of soaring college costs in the United States. Despite well-established...     

Carrying Capacity Reconsidered

The concept of carrying capacity has gained broad currency, although some population ecologists are dubious about its value. This paper assesses the utility of the concept and develops an alternative understanding of population growth. First, carrying capacity is viewed in historical perspective and evidence that is supposed to support it is criticized. Then the underlying assumptions upon which it rests are reexamined. Limits to growth are seen to be both multiple and variable. The mechanism that is supposed to regulate population is critically reviewed. And the assumptions of balance in nature and equilibrium in biotic communities are reevaluated. These assumptions having been found wanting, population growth is reassessed in relation to environmental variability. The strategies by which different species cope with variability are described, and the windfall effect, which causes some populations to grow rapidly and then collapse, is identified. Finally, it is suggested that carrying capacity may be a self-validating belief and that is has limited relevance to human population growth, which is better understood in other ways.     

Adolescent Weight and Depressive Symptoms: For Whom is Weight a Burden?*

Objective. Adolescent weight and depressive symptoms are serious population health concerns in their own right and as they relate to each other. This study asks whether relationships between weight and depressive symptoms vary by sex and race/ethnicity because both shape experiences of weight and psychological distress. Methods. Results are based on multivariate analyses of National Longitudinal Study of Adolescent Health (Add Health) data. Results. There are no associations between adolescent girls' weight and depressive symptoms, but these associations vary considerably among boys. Underweight is associated with depressive symptoms among all boys and subpopulations of white and Hispanic boys. Among Hispanic boys, those who are overweight (vs. normal weight) have a lower probability of reporting depressive symptoms. Finally, among normal weight boys, Hispanics and blacks are more likely to report depressive symptoms than whites. Conclusions. Findings are a reminder that understanding population health issues sometimes requires a focus on subpopulations, not simply the population as a whole.     

Models, assumptions and model checking in ecological regressions

Ecological regression is based on assumptions that are untestable from aggregate data. However, these assumptions seem more questionable in some applications than in others. There has been some research on implicit models of individual data underlying aggregate ecological regression modelling. We discuss ways in which these implicit models can be checked from aggregate data. We also explore the differences in applications of ecological regressions in two examples: estimating the effect of radon on lung cancer in the United States and estimating voting patterns for different ethnic groups in New York City.     

Pond age and riparian zone proximity influence anuran occupancy of urban retention ponds

Urbanization is widespread throughout the United States and negatively affects many wildlife populations. However, certain urban features, such as retention ponds, may provide habitat for some species, such as amphibians. This study examines the influence of riparian zone proximity and pond age on retention pond occupancy by anurans. We identified and estimated the age of 25 retention ponds near Charlotte, North Carolina, USA and used a geographic information system to determine the distance to the nearest riparian zone. Occupancy modeling indicated that anuran presence decreased with increasing distance to riparian zone. Pond age also appeared to be an important factor, but the effect varied among species. Although the results of this study demonstrate the potential value of retention ponds to anurans, it is important to be conservative in estimating the ability of these ponds to sustain amphibian populations in urbanized regions.