Genetic influence on age at first birth of female twins born in the UK, 1919–68

Using a sample of monozygotic (945, 42?per cent) and dizygotic (1,329, 58?per cent) twin pairs born 1919–68 in the UK, we applied innovative tobit models to investigate genetic and environmental influences on age at first birth (AFB). We found that a substantial part (40?per cent) of the variation in AFB is caused by latent family characteristics. Genetic dispositions (26?per cent) play a more important role than the shared environment of siblings (14?per cent), with the non-shared environment/measurement error having the strongest influence (60?per cent). Like previous studies, this study reveals marked changes in estimates over time, and supports the idea that environmental constraints (war or economic crisis) suppress and normative freedom (sexual revolution) promotes the activation of genetic predispositions that affect fertility. We show that the exclusion of censored information (i.e., on the childless) by previous studies biased their results.

Supplementary material for this article is available at: http://dx.doi.org/10.1080/00324728.2015.1056823     

A Problematic Integration Approach to Capturing the Cognitive, Cultural, and Communicative Experiences of Hurricane Katrina Volunteers

This essay outlines an applied approach for examining message reception and processing among natural disaster volunteers. It is argued that an applied approach provides analysis of volunteers' decision-making processes that extends to cognitive, cultural, and communicative influences on the decision to volunteer. Implications for future research on volunteerism in natural disasters are discussed and policy-making implications are addressed.     

Clinic Capacity Management: Planning Treatment Programs that Incorporate Adherence

For infectious diseases like tuberculosis and HIV, treatment adherence plays an important role in treatment effectiveness and epidemic control. Studies of some infectious diseases indicate that patients who live closer to their health facilities maintain higher adherence; however, most models ignore the heterogeneity of patients' adherence. Clinics must balance knowledge about adherence with epidemic growth when creating successful treatment programs. We develop an optimization model that integrates a clinic's capacity decisions with population health outcomes. We find that incorporating adherence into clinic planning models can lead to decisions that significantly improve outcomes. For example, in a realistic case study of the HIV epidemic in Zambia, we find that decision makers who ignore decreasing adherence make suboptimal decisions and overestimate the effectiveness of their treatment programs by as much as 94%. Our model is a first step toward understanding the relationship between adherence and health delivery.     

Analysing US State Legislative Resolutions on Immigrants and Immigration: The Role of Immigration Federalism***

Immigration in the United States is traditionally thought of as a federal‐level policy, but in recent years, states have been exceedingly active in this domain. We analyse the context and discourse of immigration‐related legislative resolutions from Southern border‐states, recipients of the heaviest immigration flows, and find that states do not respond in the same way to immigration challenges, and these differences occur over time and space. Some states seek to federalize the issue and push Congress to take action, while others are slowly incorporating immigrants into domestic politics and have begun to treat them as yet another state constituency. These findings have significant implications both for federal‐state relations in the immigration realm, and for immigrants themselves.     

The Biodemography of Fertility: A Review and Future Research Frontiers

The social sciences have been reticent to integrate a biodemographic approach to the study of fertility choice and behaviour, resulting in theories and findings that are largely socially-deterministic. The aim of this paper is to first reflect on reasons for this lack of integration, provide a review of previous examinations, take stock of what we have learned until now and propose future research frontiers. We review the early foundations of proximate determinants followed by behavioural genetic (family and twin) studies that isolated the extent of genetic influence on fertility traits. We then discuss research that considers gene and environment interaction and the importance of cohort and country-specific estimates, followed by multivariate models that explore motivational precursors to fertility and education. The next section on molecular genetics reviews fertility-related candidate gene studies and their shortcomings and on-going work on genome wide association studies. Work in evolutionary anthropology and biology is then briefly examined, focusing on evidence for natural selection. Biological and genetic factors are relevant in explaining and predicting fertility traits, with socio-environmental factors and their interaction still key in understanding outcomes. Studying the interplay between genes and the environment, new data sources and integration of new methods will be central to understanding and predicting future fertility trends.     

Pairwise comparisons for proportions estimated by pooled testing

When estimating the prevalence of a rare trait, pooled testing can confer substantial benefits when compared to individual testing. In addition to screening experiments for infectious diseases in humans, pooled testing has also been exploited in other applications such as drug testing, epidemiological studies involving animal disease, plant disease assessment, and screening for rare genetic mutations. Within a pooled-testing context, we consider situations wherein different strata or treatments are to be compared with the goals of assessing significant and practical differences between strata and ranking strata in terms of prevalence. To achieve these goals, we first present two simultaneous pairwise interval estimation procedures for use with pooled data. Our procedures rely on asymptotic results, so we investigate small-sample behavior and compare the two procedures in terms of simultaneous coverage probability and mean interval length. We then present a unified approach to determine pool sizes which deliver desired coverage properties while taking testing costs and interval precision into account. We illustrate our methods using data from an observational HIV study involving heterosexual males who use intravenous drugs.     

Civic Culture Meets the Digital Divide: The Role of Community Electronic Networks

The concept of social capital reflects the norms and social relations embedded in the social structure of societies that enable people to coordinate community action to achieve desired goals. Our research focuses on the role that norms of cooperation and civic and political culture play in addressing the "digital divide" in computer use and Internet access. We review evidence from mail surveys of randomly selected respondents in two rural Minnesota communities as well as qualitative focus group and archival evidence suggesting that the communities have adopted different approaches to technology diffusion. Whether information technology is viewed as a public or private good depends in part on the civic culture of a community.     

Turning to the Courts: A Quantitative Analysis of the Gay and Lesbian Movement’s Use of Legal Mobilization

We quantitatively examine the factors influencing the lesbian and gay movement’s involvement in state-level appellate cases through an analysis of Lambda Legal’s judicial agenda from 1981 through 2000. We combine a list of state appellate cases involving gay and lesbian rights during this period with data from Lambda’s “Docket Update” to create a data set that identifies which cases Lambda was involved in. We theorize that Lambda’s involvement will be shaped by the potential policy implications of the case, the organization’s ability to influence the outcome, and organizational membership concerns. Using logistic regression, we examine the effect of case characteristics, the political and cultural climate in the state, and variations in the state’s lesbian and gay community on the likelihood of Lambda participating in a particular state-level case. We add to the understanding of movement tactical decisions and the factors influencing the likelihood of legal mobilization.