Abortion Legalization and Child Living Circumstances: Who is the "Marginal Child?"

We estimate the impact of changes in abortion access in the early 1970s on the average living standards of cohorts born in those years. In particular, we address the selection inherent in the abortion decision: is the marginal child who is not born when abortion access increases more or less disadvantaged than the average child? Legalization of abortion in five states around 1970, followed by legalization nationwide due to the 1973 Roe v. Wade decision, generates natural variation which can be used to estimate the effect of abortion access. We find that cohorts born after abortion was legalized experienced a significant reduction in a number of adverse outcomes. Our estimates imply that the marginal child who was not born due to legalization would have been 70% more likely to live in a single parent family, 40% more likely to live in poverty, 50% more likely to receive welfare, and 35% more likely to die as an infant. These selection effects imply that the legalization of abortion saved the government over $14 billion in welfare expenditures through 1994.

Abortion and Selection

The introduction of legalized abortion in the early 1970s led to dramatic changes in fertility behavior. Some research has suggested as well that there were important impacts on cohort outcomes, but this literature has been limited and controversial. In this paper, we provide a framework for understanding the mechanisms through which abortion access affects cohort outcomes, and use that framework to both address inconsistent past methodological approaches, and provide evidence on the long-run impact on cohort characteristics. Our results provide convincing evidence that abortion legalization altered young adult outcomes through selection. In particular, we find evidence that lower costs of abortion led to improved outcomes in the birth cohort in the form of an increased likelihood of college graduation, lower rates of welfare use, and lower odds of being a single parent. We also find that our empirical innovations do not substantially alter earlier results regarding the relationship between abortion and crime, although most of that relationship appears to reflect cohort size effects rather than selection.

Abortion Legalization and Child Living Circumstances: Who is the \u27Marginal Child\u27?

We estimate the impact of changes in abortion access in the early 1970s on the average living standards of cohorts born in those years. In particular, we address the selection inherent in the abortion decision: is the marginal child who is not born when abortion access increases more or less disadvantaged than the average child? Legalization of abortion in five states around 1970, followed by legalization nationwide due to the 1973 Roe v. Wade decision, generates natural variation which can be used to estimate the effect of abortion access. We find that cohorts born after abortion was legalized experienced a significant reduction in a number of adverse outcomes. Our estimates imply that the marginal child who was not born due to legalization would have been 70% more likely to live in a single parent family, 40% more likely to live in poverty, 50% more likely to receive welfare, and 35% more likely to die as an infant. These selection effects imply that the legalization of abortion saved the government over $14 billion in welfare expenditures through 1994

Abortion and Selection

Abortion legalization in the early 1970s led to dramatic changes in fertility. Some research has suggested that it altered cohort outcomes, but this literature has been limited and controversial. In this paper, we provide a framework for understanding selection mechanisms and use that framework to both address inconsistent past methodological approaches and provide evidence on the long-run impact on cohort characteristics. Our results indicate that lower-cost abortion brought about by legalization altered young adult outcomes through selection. In particular, it increased likelihood of college graduation, lower rates of welfare use, and lower odds of being a single parent

An experimental study of airfoil instability tonal noise with trailing edge serrations

This paper presents an experimental study of the effect of trailing edge serrations on airfoil instability noise. Detailed aeroacoustic measurements are presented of the noise radiated by an NACA-0012 airfoil with trailing edge serrations in a low to moderate speed flow under acoustical free field conditions. The existence of a separated boundary layer near the trailing edge of the airfoil at an angle of attack of 4.2 degree has been experimentally identified by a surface mounted hot-film arrays technique. Hot-wire results have shown that the saw-tooth surface can trigger a bypass transition and prevent the boundary layer from becoming separated. Without the separated boundary layer to act as an amplifier for the incoming Tollmien-Schlichting waves, the intensity and spectral characteristic of the radiated tonal noise can be affected depending upon the serration geometry. Particle Imaging Velocimetry (PIV) measurements of the airfoil wakes for a straight and serrated trailing edge are also reported in this paper. These measurements show that localized normal-component velocity fluctuations that are present in a small region of the wake from the laminar airfoil become weakened once serrations are introduced. Owing to the above unique characteristics of the serrated trailing edges, we are able to further investigate the mechanisms of airfoil instability tonal noise with special emphasis on the assessment of the wake and non-wake based aeroacoustic feedback model. It has been shown that the instability tonal noise generated at an angle of attack below approximately one degree could involve several complex mechanisms. On the other hand, the non-wake based aeroacoustic feedback mechanism alone is sufficient to predict all discrete tone frequencies accurately when the airfoil is at a moderate angle of attack

Adding a Little Reality to Building Ontologies for Biology

BACKGROUND: Many areas of biology are open to mathematical and computational modelling. The application of discrete, logical formalisms defines the field of biomedical ontologies. Ontologies have been put to many uses in bioinformatics. The most widespread is for description of entities about which data have been collected, allowing integration and analysis across multiple resources. There are now over 60 ontologies in active use, increasingly developed as large, international collaborations. There are, however, many opinions on how ontologies should be authored; that is, what is appropriate for representation. Recently, a common opinion has been the "realist" approach that places restrictions upon the style of modelling considered to be appropriate. METHODOLOGY/PRINCIPAL FINDINGS: Here, we use a number of case studies for describing the results of biological experiments. We investigate the ways in which these could be represented using both realist and non-realist approaches; we consider the limitations and advantages of each of these models. CONCLUSIONS/SIGNIFICANCE: From our analysis, we conclude that while realist principles may enable straight-forward modelling for some topics, there are crucial aspects of science and the phenomena it studies that do not fit into this approach; realism appears to be over-simplistic which, perversely, results in overly complex ontological models. We suggest that it is impossible to avoid compromise in modelling ontology; a clearer understanding of these compromises will better enable appropriate modelling, fulfilling the many needs for discrete mathematical models within computational biology

A human MUTYH variant linking colonic polyposis to redox degradation of the [4Fe4S]²⁺ cluster

The human DNA repair enzyme MUTYH excises mispaired adenine residues in oxidized DNA. Homozygous MUTYH mutations underlie the autosomal, recessive cancer syndrome MUTYH-associated polyposis. We report a MUTYH variant, p.C306W (c.918C>G), with a tryptophan residue in place of native cysteine, that ligates the [4Fe4S] cluster in a patient with colonic polyposis and family history of early age colon cancer. In bacterial MutY, the [4Fe4S] cluster is redox active, allowing rapid localization to target lesions by long-range, DNA-mediated signalling. In the current study, using DNA electrochemistry, we determine that wild-type MUTYH is similarly redox-active, but MUTYH C306W undergoes rapid oxidative degradation of its cluster to [3Fe4S]^+, with loss of redox signalling. In MUTYH C306W, oxidative cluster degradation leads to decreased DNA binding and enzyme function. This study confirms redox activity in eukaryotic DNA repair proteins and establishes MUTYH C306W as a pathogenic variant, highlighting the essential role of redox signalling by the [4Fe4S] cluster

A human MUTYH variant linking colonic polyposis to redox degradation of the [4Fe4S]²⁺ cluster

The human DNA repair enzyme MUTYH excises mispaired adenine residues in oxidized DNA. Homozygous MUTYH mutations underlie the autosomal, recessive cancer syndrome MUTYH-associated polyposis. We report a MUTYH variant, p.C306W (c.918C>G), with a tryptophan residue in place of native cysteine, that ligates the [4Fe4S] cluster in a patient with colonic polyposis and family history of early age colon cancer. In bacterial MutY, the [4Fe4S] cluster is redox active, allowing rapid localization to target lesions by long-range, DNA-mediated signalling. In the current study, using DNA electrochemistry, we determine that wild-type MUTYH is similarly redox-active, but MUTYH C306W undergoes rapid oxidative degradation of its cluster to [3Fe4S]^+, with loss of redox signalling. In MUTYH C306W, oxidative cluster degradation leads to decreased DNA binding and enzyme function. This study confirms redox activity in eukaryotic DNA repair proteins and establishes MUTYH C306W as a pathogenic variant, highlighting the essential role of redox signalling by the [4Fe4S] cluster

The state of the Martian climate

60°N was +2.0°C, relative to the 1981–2010 average value (Fig. 5.1). This marks a new high for the record. The average annual surface air temperature (SAT) anomaly for 2016 for land stations north of starting in 1900, and is a significant increase over the previous highest value of +1.2°C, which was observed in 2007, 2011, and 2015. Average global annual temperatures also showed record values in 2015 and 2016. Currently, the Arctic is warming at more than twice the rate of lower latitudes