An Empirical Note on the Social and Geographic Correlates of Mexican Migration to the Southern United States

This research empirically examines differences in the socioeconomic correlates of Mexican migrants to the southern region of the United States. More specifically, the research considers differences between Mexican immigrants choosing the South and those choosing other U.S. destinations. Using general estimating equations, the study provides evidence that several characteristics distinguish the stream of recent migrants choosing southern destinations. Notably, rural origins as well as rural destinations have substantial explanatory power. The results also show that immigrants to the South are likely to be pioneers in the sense that they do not have strong family-specific migration capital and are likely to be from a community without a long history of sending migrants to the United States. Immigrants choosing the South are also more likely to be undocumented. Additionally, they are far more likely to have arrived following implementation of NAFTA. Ownership of houses is also a distinguishing feature of these migrants

Selective Migration and the Educational Brain Drain from the Lower Mississippi Delta Region in 1975-80

Using a unique source of information about migration, this paper calculates the rates of net migration by age and educational level for the Lower Mississippi Delta region for the period of 1975-80, compares different categories of counties in the Delta, and compares Delta areas with non-Delta areas of the seven Delta states. It shows substantial losses of more highly educated persons, especially the young, from all rural counties, but especially for the core rural Delta counties

Antecedents of Infant Mortality: An Analysis of Risk Factors in Rural and Urban Arkansas

This research examines the relationship between social and biological characteristics of the infant and mother and the probability of infant survival through the first year of life. The research also includes a consideration of the influence of residence (rural vs. urban). Employing linked birth and death certificate data for Arkansas (1985-1989), a logit model was estimated to assess the impact of social and biological factors on the probability of survival. The results indicate that metropolitan residence is positively associated with infant survival, but only at a marginal significance level. Other notable results include the importance of prenatal care and a lack of significance of race when other factors are controlled

Farm Operator Satisfaction with Retail Pesticide Suppliers in the Arkansas Delta

Two hundred ninety farm operators in the three easternmost crop reporting districts in Arkansas responded to a mail survey in November 1996 about their preferences and satisfaction with retail pesticide suppliers.Results show most farmers are quite satisfied with their main retail pesticide supplier, although 55.5% of the farm operators used more than one retail pesticide supplier in 1996. Users of multiple suppliers were less satisfied with their suppliers than those using only one supplier. Availability of certain pesticides was the most frequently mentioned reason for using multiple suppliers. Several attributes were important in selecting the main supplier with reputation being the most important, followed by delivery services, long-term relationship with salesperson, and price. Although not rated highly by the farm operators, location was also an important consideration in choosing a main supplier

An Empirical Examination of Characteristics of Mexican Migrants to Metropolitan and Nonmetropolitan

ABSTRACT This research examines differences between those Mexican migrants choosing metropolitan destinations and those choosing destinations outside metropolitan areas of the United States. Using general estimating equations, the study presents data indicating that since the 1960s migrants choosing rural destinations are less fluent in English, slightly older, much less educated, far more likely to be unskilled, more likely to be married, and more likely to be undocumented. The picture is more complex when consideration is restricted to those migrants arriving in rural areas since the passage of the North American Free Trade Agreement. These migrants are far more likely to be single, have more education but have less English fluency, have less work experience, and have less family experience with migration to the United States. They are more likely to come from small towns and rural areas of Mexico

A Demographic Approach to Race and Ethnicity in Metropolitan and Non-Metropolitan Regions of Arkansas, 1990 and 1999

This manuscript provides an empirical portrait of emergent trends in the growth, distribution, and racial and ethnic composition of Arkansas’ resident population. Particular attention is given to variation in the racial and ethnic composition of the estimated population among different regions of the state. During the 1990’s, racial and ethnic diversity increased statewide due in large part to Hispanic population growth in all regions. Black population growth was greatest in central Arkansas while Asian and Native American population growth increased most rapidly in the northwest metropolitan regions of the state. Overall, both metropolitan and non-metropolitan Arkansas communities have a more diverse mix of ethnic populations than has been known in the past

A Sensitivity Study of the Enceladus Torus

We have developed a homogeneous model of physical chemistry to investigate the neutral-dominated, water-based Enceladus torus. Electrons are treated as the summation of two isotropic Maxwellian distributions$-$a thermal component and a hot component. The effects of electron impact, electron recombination, charge exchange, and photochemistry are included. The mass source is neutral H$_2$O, and a rigidly-corotating magnetosphere introduces energy via pickup of freshly-ionized neutrals. A small fraction of energy is also input by Coulomb collisions with a small population ($<$ 1%) of supra-thermal electrons. Mass and energy are lost due to radial diffusion, escaping fast neutrals produced by charge exchange and recombination, and a small amount of radiative cooling. We explore a constrained parameter space spanned by water source rate, ion radial diffusion, hot-electron temperature, and hot-electron density. The key findings are: (1) radial transport must take longer than 12 days; (2) water is input at a rate of 100--180 kg s$^{-1}$; (3) hot electrons have energies between 100 and 250 eV; (4) neutrals dominate ions by a ratio of 40:1 and continue to dominate even when thermal electrons have temperatures as high as $\approx$ 5 eV; (5) hot electrons do not exceed 1% of the total electron population within the torus; (6) if hot electrons alone drive the observed longitudinal variation in thermal electron density, then they also drive a significant variation in ion composition.Comment: 9 pages text, 3 tables, 9 figure

Evolutionary connectionism: algorithmic principles underlying the evolution of biological organisation in evo-devo, evo-eco and evolutionary transitions

The mechanisms of variation, selection and inheritance, on which evolution by natural selection depends, are not fixed over evolutionary time. Current evolutionary biology is increasingly focussed on understanding how the evolution of developmental organisations modifies the distribution of phenotypic variation, the evolution of ecological relationships modifies the selective environment, and the evolution of reproductive relationships modifies the heritability of the evolutionary unit. The major transitions in evolution, in particular, involve radical changes in developmental, ecological and reproductive organisations that instantiate variation, selection and inheritance at a higher level of biological organisation. However, current evolutionary theory is poorly equipped to describe how these organisations change over evolutionary time and especially how that results in adaptive complexes at successive scales of organisation (the key problem is that evolution is self-referential, i.e. the products of evolution change the parameters of the evolutionary process). Here we first reinterpret the central open questions in these domains from a perspective that emphasises the common underlying themes. We then synthesise the findings from a developing body of work that is building a new theoretical approach to these questions by converting well-understood theory and results from models of cognitive learning. Specifically, connectionist models of memory and learning demonstrate how simple incremental mechanisms, adjusting the relationships between individually-simple components, can produce organisations that exhibit complex system-level behaviours and improve the adaptive capabilities of the system. We use the term “evolutionary connectionism” to recognise that, by functionally equivalent processes, natural selection acting on the relationships within and between evolutionary entities can result in organisations that produce complex system-level behaviours in evolutionary systems and modify the adaptive capabilities of natural selection over time. We review the evidence supporting the functional equivalences between the domains of learning and of evolution, and discuss the potential for this to resolve conceptual problems in our understanding of the evolution of developmental, ecological and reproductive organisations and, in particular, the major evolutionary transitions