How important was international immigration for the U.S. and its demography during the nineteenth century? This paper investigates, quantitatively, its effect on the westward movement of population and the regional and secular changes in fertility. Beside immigration, two alternative forces are considered: technological progress and the land policy (the Homestead Act). An optimal growth model w...

Some of the transitional periods of Britain during the first millennium A.D. are traditionally associated with the movement of people from continental Europe, composed largely of invading armies (e.g., the Roman, Saxon, and Viking invasions). However, the extent to which these were migrations (as opposed to cultural exchange) remains controversial. We investigated the history of migration by wo...

The Bisexual Galton–Watson branching process (BGWP), introduced by Daley (1968), is a discrete time branching model that is well-suited to describing the probabilistic evolution of populations where females and males coexist and form couples (mating units) which reproduce independently with the same offspring probability distribution. To describe the probabilistic evolution of more complicated ...

conclusion upon these results, immigration and family deprivation are potent risk factors for occurrence of infection results among 274 patients with hiv infection/aids (224 male and 50 female) in sistan and baluchestan province in southeast of iran, 65 cases (41 male, 24 female) were from saravan (a city in sistan and baluchestan). out of 41 men with hiv/aids in saravan, 21 cases had a history...

Abstract From 2014 onwards Poland witnessed an unprecedented inflow of immigrant workers from Ukraine. Coupled with strong labour demand, this surge in supply provided a major contribution to Poland’s economic growth. However, due problems capturing immigration Labour Force Survey data has remained hitherto largely unaccounted official data. This paper uses range alternative sources estimate th...

Ecological communities are typically open to the immigration and emigration of individuals, and also variable through time. In this paper we argue that interesting and potentially important effects arise when one splices together spatial fluxes and temporal variability. The particular system we examine is a sink habitat, where a species faces deterministic extinction but is rescued by recurrent...

Over 4 months and about 1 year, coastal cutthroat trout (Oncorhynchus clarki clarki) ≥ age-1 in Little Jones Creek, California, remained at similar rates in pools with and without large woody debris. This result was based on attempts in July and November 1995 to collect and tag all fish in 22 pools and three collections of fish from the same pools in November 1995, May 1996, and August 1996. Re...

We revisit the work of Borjas (1995) which has provided an influential positive theory of immigration policy. An important feature of his framework is the focus on the skill-composition of immigrants and we retain this feature in our paper. Our contribution to this literature is to extend his analysis in a number of directions. First, we study the immigration surplus in the context of a general...