Explaining US Immigration 1971-1998

In this paper we develop and estimate a model to explain the level and source country composition of immigration to the United States since the early 1970s. The model incorporates ratios to the US of source country income and education, and demographic structure, as well as relative inequality as suggested by the Roy model applied to migrant selection. In addition we incorporate the 'friends and relatives effect' as reflected in the stock of previous immigrants and a variety of variables representing different dimensions of the immigration quotas set by policy. We estimate our immigration model on a panel of 81 source countries for the years 1971 to 1998. The results strongly support the influence of economic and demographic variables and geographic characteristics as well as policy variables. We use the results to shed light on the factors that influenced the composition of US immigration by source region. And we provide a further check on its plausibility by simulating the effects of the key changes in immigration policy since the late 1970s.

Where Do U.S. Immigrants Come From, and Why?

The United States has experienced rising immigration levels and changing source since the 1950s. The changes in source have been attributed to the 1965 Amendments to the Immigration Act that abolished country-quotas and replaced them with a system that emphasized family reunification. Some believed that the Amendments would not change the 'traditional' sources of US immigrants. Given this view, it seems all the more remarkable that the sources of immigration changed so dramatically. This paper isolates the economic and demographic fundamentals that determined immigration rates by source from 1971 to 1998 -- income, education, demographic composition and inequality. The paper also allows for persistence - big US foreign-born stocks implying a strong 'friends and neighbors' pull on current immigrant flows. Specific policy variables are included which are derived directly from the quotas allocated to different visa categories. Parameter estimates from the panel data are then used to implement counterfactual simulations that serve to isolate the effects of immigration policy as well as source-country economic and demographic conditions.

Explaining U.S. immigration, 1971-98

The authors develop and estimate a model explaining the level and country-source composition of United States immigration since the early 1970s. The model incorporates ratios of source country income, education, and demographic structure, as well as relative inequality. The authors'model also incorporates both network effects, as reflected in the stock of previous immigrants, and various controls for immigration quota policy. The model is estimated on a panel of 81 source countries for 1971-98. The results strongly support the influence of economic, demographic, and geographic variables as well as policy. The regression results are used to identify those factors that most influenced the changing composition of U.S. immigration by source.Health Monitoring&Evaluation,Public Health Promotion,Voluntary and Involuntary Resettlement,Human Migrations&Resettlements,Gender and Social Development,Health Monitoring&Evaluation,Voluntary and Involuntary Resettlement,Human Migrations&Resettlements,Gender and Social Development,Economic Theory&Research

What Explains Cross-Border Migration in Latin America?

What accounts for the differences in rates of emigration from Latin America compared with those from other sending regions such as Asia and Africa? Why do cross-border migration rates vary so much across Latin America? What explains those rates? This paper looks at evidence covering the period between the early 1970s and the late 1990s. It represents the start of a project seeking answers to these questions.

Comparative profiling of the transcriptional response to infection in two species of Drosophila by short-read cDNA sequencing

<p>Abstract</p> <p>Background</p> <p>Homology-based comparisons of the genes involved in innate immunity across many insect taxa with fully sequenced genomes has revealed a striking pattern of gene gain and loss, particularly among genes that encode proteins involved in clearing pathogens (effectors). However, limited functional annotation in non-model systems has hindered understanding of evolutionary novelties in the insect innate immune system.</p> <p>Results</p> <p>We use short read sequencing technology (Illumina/Solexa) to compare the transcriptional response to infection between the well studied model system <it>Drosophila melanogaster </it>and the distantly related drosophilid <it>D. virilis</it>. We first demonstrate that Illumina/Solexa sequencing of cDNA from infected and uninfected <it>D. melanogaster </it>recapitulates previously published microarray studies of the transcriptional response to infection in this species, validating our approach. We then show that patterns of transcription of homologous genes differ considerably between <it>D. melanogaster </it>and <it>D. virilis</it>, and identify potential candidates for novel components of the <it>D. virilis </it>immune system based on transcriptional data. Finally, we use a proteomic approach to characterize the protein constituents of the <it>D. virilis </it>hemolymph and validate our transcriptional data.</p> <p>Conclusion</p> <p>These results suggest that the acquisition of novel components of the immune system, and particularly novel effector proteins, may be a common evolutionary phenomenon.</p

The Benefits of Breastfeeding: An introduction for Health Educators

Currently 16% of Americans breastfeed their children for at least 12 months as recommended by the AAP, which is well below the HP 2010 goal of 25%. Breastfed infants receive benefits that can improve their health throughout their lives. The benefits of breastfeeding for children include increased resistance to infectious diseases, such as gastroenteritis, respiratory tract infections, and ear infections. Breastfed children also display lower rates of chronic diseases including diabetes, obesity, asthma, and leukemia. The choice to breastfeed results in economic benefits from lower health care costs and from reduced spending on infant formula. The Healthy People 2010 targets are reviewed along with several studies of interventions to increase breastfeeding rates. Health educators must work to increase breastfeeding rates

Accounting for the utilization of a N₂O mitigation tool in the IPCC inventory methodology for agricultural soils

In this study we review recent studies where dicyandiamide was used as a nitrification inhibitor to reduce both N₂O emissions from urine patches and nitrate leaching from pasture systems, and which led to the development of a commercial product for use on farmland. On average, emissions of N₂O and nitrate leaching were reduced by 72% and 61%, respectively. This study then demonstrates how a mitigation tool can be accounted for in the Intergovernmental Panel on Climate Change's inventory methodology when constructing an inventory of New Zealand's agricultural soil N₂O emissions. The current New Zealand specific emission factors for EF1 (0.01), EF3PRP (0.01) and FracLEACH (0.07) are amended to values of 0.0058, 0.0058 and 0.0455. Examples are also given, based on OVERSEER TM models, of the implications of farm management scenarios on N₂O inventories and total greenhouse gas production when using a N₂O mitigation tool; CO₂ equivalents kg⁻¹ milk solid decreased from 14.2 to as little as 11.7, depending on the management scenario modelled

Facile C_sp²-C_sp² bond cleavage in oxalic acid-derived radicals

Oxalate decarboxylase (OxDC) catalyzes the Mn-dependent conversion of the oxalate monoanion into CO2 and formate. Many questions remain about the catalytic mechanism of OxDC although it has been proposed that the reaction proceeds via substrate-based radical intermediates. Using coupled cluster theory combined with implicit solvation models we have examined the effects of radical formation on the structure and reactivity of oxalic acid-derived radicals in aqueous solution. Our results show that the calculated solution-phase free-energy barrier for C–C bond cleavage to form CO2 is decreased from 34.2 kcal/mol for oxalic acid to only 9.3 kcal/mol and a maximum of 3.5 kcal/mol for the cationic and neutral oxalic acid-derived radicals, respectively. These studies also show that the C–C σ bonding orbital of the radical cation contains only a single electron, giving rise to an elongated C–C bond distance of 1.7 Å; a similar lengthening of the C–C bond is not observed for the neutral radical. This study provides new chemical insights into the structure and stability of plausible intermediates in the catalytic mechanism of OxDC, and suggests that removal of an electron to form a radical (with or without the concomitant loss of a proton) may be a general strategy for cleaving the unreactive C–C bonds between adjacent sp2-hybridized carbon atoms

Small Scale Response and Modeling of Periodically Forced Turbulence

The response of the small scales of isotropic turbulence to periodic large scale forcing is studied using two-point closures. The frequency response of the turbulent kinetic energy and dissipation rate, and the phase shifts between production, energy and dissipation are determined as functions of Reynolds number. It is observed that the amplitude and phase of the dissipation exhibit nontrivial frequency and Reynolds number dependence that reveals a filtering effect of the energy cascade. Perturbation analysis is applied to understand this behavior which is shown to depend on distant interactions between widely separated scales of motion. Finally, the extent to which finite dimensional models (standard two-equation models and various generalizations) can reproduce the observed behavior is discussed

Seasonal Variation of Myostatin Gene Expression in Pectoralis Muscle of House Sparrows (Passer domesticus) Is Consistent with a Role in Regulating Thermogenic Capacity and Cold Tolerance

ABSTRACT Winter acclimatization in small birds overwintering in cold climates, including house sparrows (Passer domesticus), is associated with improved cold tolerance, elevated summit metabolic rates (M sum p maximum cold-induced metabolic rate), and increased pectoralis muscle mass compared to summer birds. Myostatin is a potent autocrine/paracrine inhibitor of skeletal muscle growth in mammals and birds and is a potential candidate for regulation of seasonal phenotypic flexibility in birds. As a first step toward examining such a role for myostatin in small birds, we measured summer and winter gene expression of myostatin and its potential metalloproteinase activators TLL-1 and TLL-2 in house sparrows from southeastern South Dakota. Gene expression of myostatin decreased significantly in winter, with summer values exceeding winter values by 1.52-fold. Moreover, gene expression of TLL-1 was also significantly reduced in winter, with summer values exceeding winter values by 1.55-fold. These data are consistent with the hypothesis that the winter increases in pectoralis muscle mass, M sum , and cold tolerance in house sparrows are mediated by reduced levels of myostatin and its activator TLL-1, and they suggest the possibility that myostatin may be a common mediator of phenotypic flexibility of muscle mass in birds