AJAE Appendix: Nonlinear Dynamics and Structural Change in the U.S. Hog-Corn Ratio: A Time-Varying Star Approach

The material contained herein is supplementary to the article named in the title and published in the American Journal of Agricultural Economics, Volume 88, Number 1, February 2006.Agribusiness,

Convergence (and Divergence) in the Biological Standard of Living in the United States, 1820-1900

Standard economic indicators suggest that the United States experienced long-run economic growth throughout the nineteenth century. However, biological indicators, including human stature, offer a different picture, rising early in the century, falling (on average) mid-century, and rising again at the end of the century. This pattern varied across geographical regions. Using a unique data set, consisting of mean adult stature by state, we test for convergence in stature among states in the nineteenth century. We find that during the period of declining mean stature, heights actually diverged. Later in the century we find a type of “negative” convergence indicating that stature among states tended to converge to a new, lower steady state. Only towards the end of the century do we find classic convergence behavior. We argue that the diversity of economic experiences across regions, e.g. urbanization, industrialization, and transportation improvements, explain this pattern of divergence and then convergence.

Spin-Filtering Multiferroic-Semiconductor Heterojunctions

We report on the structural and electronic properties of the interface between the multiferoic oxide YMnO$_3$ and wide band-gap semiconductor GaN studied with the Hubbard-corrected local spin density approximation (LSDA+U) to density-functional theory (DFT). We find that the band offsets at the interface between antiferromagnetically ordered YMnO$_3$ and GaN are different for spin-up and spin-down states. This behavior is due to the spin splitting of the valence band induced by the interface. The energy barrier depends on the relative orientation of the electric polarization with respect to the polarization direction of the GaN substrate suggesting an opportunity to create magnetic tunnel junctions in this materials system.Comment: 4 pages, 4 figure

Oxidation processes in magneto-optic and related materials

The surface oxidation processes of thin films of magneto-optic materials, such as the rare-earth transition metal alloys have been studied, starting in ultrahigh vacuum environments, using surface analysis techniques, as a way of modeling the oxidation processes which occur at the base of a defect in an overcoated material, at the instant of exposure to ambient environments. Materials examined have included FeTbCo alloys, as well as those same materials with low percentages of added elements, such a Ta, and their reactivities to both O2 and H2O compared with materials such as thin Fe films coated with ultrathin adlayers of Ti. The surface oxidation pathways for these materials is reviewed, and XPS data presented which indicates the type of oxides formed, and a critical region of Ta concentration which provides optimum protection

Development and characterization of a chemically defined food for Drosophila

Diet can affect a spectrum of biological processes ranging from behavior to cellular metabolism. Yet, the precise role of an individual dietary constituent can be a difficult variable to isolate experimentally. A chemically defined food (CDF) permits the systematic evaluation of individual macro- and micronutrients. In addition, CDF facilitates the direct comparison of data obtained independently from different laboratories. Here, we report the development and characterization of a CDF for Drosophila. We show that CDF can support the long-term culture of laboratory strains and demonstrate that this formulation has utility in isolating macronutrient from caloric density requirements in studies of development, longevity and reproduction

The Evolution of Public Sector Pension Plans in the United States

Municipal governments in the U.S. began offering retirement plans for their workers in the mid-19th century, and state governments followed in the early 20th century. As these plans matured, they confronted economic, social, and political challenges, including the creation of the Social Security system, which subsequently shaped their structure, governance, and generosity. After reviewing this history, we employ data from all 50 states to estimate a pension benefit equation for hypothetical workers and explain differences in the generosity of plans across states and types of workers covered. We show that population growth, plan funding, union representation, and participation in Social Security influenced the generosity of the plans