Primary and repeat migration: comparisons of Hispanic, Black and non-Hispanic white migration in the United States

Working PaperRepetitive behavior is widespread in human life. This applies in areas of behaviors that are typically infrequent as well as normative daily routines. Yet, some individual never engage in some behaviors and individuals who initiate particular behaviors differ in the extent to which the behavior is repeated. In demography, one of the areas in which this general principle applies is between prior migration and subsequent migration with prior migrants being much more likely to migrate again than individual who have never migrated are to make a first migration. A major classification that emerged from this research was between primary migration and repeat migration with length of residence as a key consideration for prior migrants. Although a rich body of research emerged on this relationship (Goldstein 1954; DaVanzo and Morrison 1981) little recent research has built on this important area of migration research. Also, while there is an extensive body of research on Hispanic immigrants in the United States there is little research that compares the internal migration of Hispanics with non-Hispanic Whites and Blacks. A common note in the early research on primary and repeat migration was the need to examine the extent to which the relationship held across socioeconomic groups and settings. The main purpose of this research is to examine the extent to which Hispanic, Black and White primary and repeat migration rates differ once other migration related variables are controlled. Data from the National Longitudinal Survey of Youth that began in 1979 are used in the analysis. During the study period the respondents transit the ages during which families and careers are typically launched and when migration rates are high

Political, Economic and Social Dominance of Major Cities in East Asia During the Twentieth Century

One of the greatest shift in human societies has been the change from dispersed settlement patterns toward a complex urban pattern. Prior to the industrialization there were only a few urban places scattered throughout the world and none could compare with numerous cities of today with respect to size and complexity. In recent decades the growth of cities in Asia has been particularly remarkable as there has been an increase in the number of medium sized cities and the growth of a number of mega cities. This urbanization of the worlds population has corresponded with other fundamental changes in human society although the relationship between urbanization and other social changes differ for time periods and regions of the world. Among the other changes were the transition from an agricultural toward a diverse economic structure and tremendous increases in population size along with declines in birth and death rates. Many researchers view these changes as being interlocked in a complex set of reciprocal causal relationship. This paper reviews explanations of urbanization with a focus on the emergence of mega cities and their relationship to smaller cities and to national levels of economic development. Special attention is given to literature on primate cities and to whether such cities hinder economic development for Asian societies

Correlation Between Luminescent Properties and Local Coordination Environment for Erbium Dopant in Yttrium Oxide Nanotubes

The local dopant coordination environment and its effect on the photoluminescent (PL) spectral features of erbium-doped yttrium oxide nanotubes (NTs) were probed by synchrotron-based x-ray diffraction (XRD), x-ray absorption near-edge spectroscopy (XANES), and extended x-ray absorption fine structure (EXAFS). XRD, XANES, and EXAFS data demonstrate that single phase solid solutions of Y (2-x) Erx O3 were formed at 0≤

Nitrate reductase 15N discrimination in Arabidopsis thaliana, Zea mays, Aspergillus niger, Pichea angusta, and Escherichia coli

Stable 15N isotopes have been used to examine movement of nitrogen (N) through various pools of the global N cycle. A central reaction in the cycle involves nitrate (NO3–) reduction to nitrite (NO2–) catalyzed via nitrate reductase (NR). Discrimination against 15N by NR is a major determinant of isotopic differences among N pools. Here, we measured in vitro 15N discrimination by several NRs purified from plants, fungi, and a bacterium to determine the intrinsic 15N discrimination by the enzyme and to evaluate the validity of measurements made using 15N-enriched NO3–. Observed NR isotope discrimination ranged from 22‰ to 32‰ (kinetic isotope effects of 1.022 to 1.032) among the different isozymes at natural abundance 15N (0.37%). As the fractional 15N content of substrate NO3– increased from natural abundance, the product 15N fraction deviated significantly from that expected based on substrate enrichment and 15N discrimination measured at natural abundance. Additionally, isotopic discrimination by denitrifying bacteria used to reduce NO3– and NO2– in some protocols became a greater source of error as 15N enrichment increased. We briefly discuss potential causes of artifactual results with enriched 15N and recommend against the use of highly enriched 15N tracers to study N discrimination in plants or soils

The Meniscus-Guided Deposition of Semiconducting Polymers

The electronic devices that play a vital role in our daily life are primarily based on silicon and are thus rigid, opaque, and relatively heavy. However, new electronics relying on polymer semiconductors are opening up new application spaces like stretchable and self-healing sensors and devices, and these can facilitate the integration of such devices into our homes, our clothing, and even our bodies. While there has been tremendous interest in such technologies, the widespread adoption of these organic electronics requires low-cost manufacturing techniques. Fortunately, the realization of organic electronics can take inspiration from a technology developed since the beginning of the Common Era: printing. This review addresses the critical issues and considerations in the printing methods for organic electronics, outlines the fundamental fluid mechanics, polymer physics, and deposition parameters involved in the fabrication process, and provides future research directions for the next generation of printed polymer electronics

Understanding the selective etching of electrodeposited ZnO nanorods

ZnO nanotubes were prepared by selective dissolution of electrodeposited nanorods. The effect of solution pH, rod morphology, and chloride ion concentration on the dissolution mechanism was studied. The selective etching was rationalized in terms of the surface energy of the different ZnO crystal faces and reactant diffusion. The nanorod diameter and chloride concentration are the most influential parameters on the dissolution mechanism because they control homogeneous dissolution or selective etching of the (110) and (002) surfaces. Bulk solution pH only has an effect on the rate of dissolution. By accurate control of the dissolution process, the nanomorphology can be tailored, and the formation of rods with a thin diameter (10-20 nm), cavity, or ultra-thin-walled tubes (2-5 nm) can be achieved