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In recently developed hierarchical age-period-cohort (HAPC) models, inferential questions arise: How can one assess or judge the significance of estimates of individual cohort and period effects in such models? And how does one assess the overall statistical significance of the cohort and/or the period effects? Beyond statistical significance is the question of substantive significance. This paper addresses these questions. In the context of empirical applications of linear and generalized linear mixed-model specifications of HAPC models using data on verbal test scores and voter turnout in U.S. presidential elections, respectively, we describe a two-step approach and a set of guidelines for assessing statistical significance. The guidelines include assessments of patterns of effects and statistical tests both for the effects of individual cohorts and time periods as well as for entire sets of cohorts and periods. The empirical applications show strong evidence that trends in verbal test scores are primarily cohort driven, while voter turnout is primarily a period phenomenon. [ABSTRACT FROM PUBLISHER]

The article discusses the relationship between birth certificates and child labor laws in the U.S. from the 1870s through the 1930s, including efforts of labor reformers to have employers use age to regulate youth employment. An overview of parents' perspectives on their children's ages, including in regard to their lack of documentation of their children's birth dates, is provided. The role that the U.S. census played in maintaining records on age and birth dates is discussed.

Scholars agree that increased intermingling of science and policy was a characteristic of the nineteenth and twentieth centuries. Within the realm of food this development has been named ‘nutrification’ or the ‘paradigm of nutritionism’. This article investigates this development in early twentieth-century Scandinavia. The thesis is that societal perceptions of age and age-related food habits influenced the pace and degree to which nutritional knowledge was integrated into and affected institutional diets. The analysis is based on dietary regulations for Danish elderly homes. In order to inform discussions around the importance of age perceptions to the nutrification of institutional food, the findings are compared with research on school meals in Norway and Denmark. The analysis concludes that age perceptions greatly influenced the extent to which diets changed in public institutions. As a result, nutrification was a process with unevenly distributed effects among Scandinavian populations. [ABSTRACT FROM AUTHOR]

Patterns of DNA methylation (DNAm) that track with aging have been identified. However, the relevance of these patterns for aging outcomes remains unclear. Longitudinal epigenome-wide DNAm information was obtained from the InCHIANTI study, a large representative European population. DNAm was evaluated using the Illumina HumanMethylation450 array on blood samples collected at baseline and 9-year follow-up: observations from 499 participants with paired longitudinal blood sample and information on differential blood count were included in analyses. A total of 56,579 markers were significantly associated with age in cross-sectional analysis of DNAm at year 9, 31,252 markers were changed significantly over the 9-year follow-up, and 16,987 markers were both cross-sectionally associated with age and significantly changed over time. Rates of change at 76 markers and year 9 level of DNAm at 88 markers were identified as strongly associated with mortality in Cox proportional hazard models adjusted for age and relevant covariates (mean follow-up time 4.4 years). Less than 0.05% of markers associated with age or that changed over time were also associated with mortality after adjusting for chronological age. Although the influence of DNAm on health and longevity remains unclear, these findings confirm that aging is associated cross-sectionally and longitudinally with robust and consistent patterns of methylation change. [ABSTRACT FROM AUTHOR]

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The religiosity of scientists is a persistent topic of interest and debate among both popular and academic commentators. Researchers look to this population as a case study for understanding the intellectual tensions between religion and science and the possible secularizing effects of education. There is little systematic study, however, of religious belief and identity among academic scientists at elite institutions, leaving a lacuna of knowledge in this area. This absence of data exists at a time when the intersection between religion and science is reaching heightened public attention. Especially with increased tensions surrounding teaching evolution in the public schools, understanding what kind of resources scientists have (particularly in terms of their own religious beliefs and practices) to transmit science to a broader religiously-motivated public is crucial. Using data from a recent survey of academic scientists at twenty-one elite U.S. research universities, we compare the religious beliefs and practices of natural and social scientists within seven disciplines as well as academic scientists to the general population. We find that field-specific and interdisciplinary differences are not as significant in predicting religiosity as other research suggests. Instead, demographic factors such as age, marital status, and presence of children in the household are the strongest predictors of religious difference among scientists. In particular, religiosity in the home as a child is the most important predictor of present religiosity among this group of scientists. We discuss the relevance these findings have for understanding issues related to current theory and public debate about the intersection between religion and science. [ABSTRACT FROM AUTHOR]