Immigration and low birthweight in the US: The role of time and timing

The literature exploring the health consequences of immigration is largely dominated by efforts to replicate, across outcomes and populations, and explain two widely observed findings: that foreign nativity is protective (yielding the “healthy migrant effect” or “immigrant paradox”) and that the health advantage of immigrants diminishes over time in the host country. In this study, we focus on the second of these patterns and provide evidence that a lifecourse perspective can help to explain the apparent deterioration in health by incorporating attention to immigrants’ timing of arrival. We examine the role of immigrants’ exposure to the US, in terms of both age at immigration and length of residence, in shaping birthweight, a well measured and consequential marker of health, and maternal smoking, an important risk factor for low birthweight.

COHABITATION: AN ELUSIVE CONCEPT

Rates of out-of-wedlock births in the US have increased over the past three decades and rates of cohabitation among unwed parents have risen. Consequently, unwed parenthood is decreasingly synonymous with single parenthood. As we focus more attention on unwed parents, their living arrangements, and relationships, it is becoming clear that cohabitation is an ambiguous concept that is difficult to measure. In this study, we use the Fragile Families and Child Wellbeing data to document how sensitive cohabitation estimates can be to various sources of information and we demonstrate that relationships among unwed parents fall along a continuum, from marriage-like cohabitation at one extreme to parents who have no contact at all with one another at the other. The results underscore the limitations of using binary measures of cohabitation to characterize parent relationships.

Mental Illness as a Barrier to Marriage Among Mothers With Out-of-Wedlock Births

This study explores how mental illness shapes transitions to marriage among unwed mothers using augmented data from the Fragile Families and Child Wellbeing study. We estimate proportional hazard models to assess the effects of mental illness on the likelihood of marriage over a five year period following a non-marital birth. Diagnosed mental illness was obtained from the survey respondents' prenatal medical records. We find that mothers with mental illness were about two thirds as likely as mothers without mental illness to marry, even after controlling for demographic characteristics, and that human capital, relationship quality, partner selection, and substance abuse explain only a small proportion of the effect of mental illness on marriage.

Local matching indicators for transport problems with concave costs

In this paper, we introduce a class of indicators that enable to compute efficiently optimal transport plans associated to arbitrary distributions of N demands and M supplies in R in the case where the cost function is concave. The computational cost of these indicators is small and independent of N. A hierarchical use of them enables to obtain an efficient algorithm

Positional information, positional error, and read-out precision in morphogenesis: a mathematical framework

The concept of positional information is central to our understanding of how cells in a multicellular structure determine their developmental fates. Nevertheless, positional information has neither been defined mathematically nor quantified in a principled way. Here we provide an information-theoretic definition in the context of developmental gene expression patterns and examine which features of expression patterns increase or decrease positional information. We connect positional information with the concept of positional error and develop tools to directly measure information and error from experimental data. We illustrate our framework for the case of gap gene expression patterns in the early Drosophila embryo and show how information that is distributed among only four genes is sufficient to determine developmental fates with single cell resolution. Our approach can be generalized to a variety of different model systems; procedures and examples are discussed in detail

Effects of Welfare Participation on Marriage

Despite interest in the potential of the welfare system as a tool to affect marriage behaviors among low-income women, little is known about how welfare participation affects decisions to marry. We employ an event history approach to examine transitions to marriage over a five-year period among mothers who have had a non-marital birth. We find that welfare participation under the Temporary Assistance to Needy Families program (TANF) reduces the likelihood of transitioning to marriage (hazard ratio is .67, p

The Role of Welfare in New Parents’ Lives

Welfare caseloads have declined substantially since the landmark PRWORA legislation of 1996, which was designed to shift the burden of supporting needy families from government to families themselves. These caseload declines have been well documented, and characteristics of recipients following the implementation of PRWORA can be gleaned from administrative and agency records. Less readily available is documentation of recent rates of welfare dependency for specific population subgroups. Mothers giving birth in the aftermath of the 1996 legislation are of particular interest since they are more likely than other potential recipients to meet work requirements and hit time limits before their children are in school.