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PubMed2004

Immigrant parents and their emigrant adolescents: the tension of inner and outer worlds.

This article examines different experiences of immigrant parents and their children in transit between the parents' ethnic world and American culture through three clinical cases: a 16-year-old male, whose mother is Persian and father East Indian and who presents with depression and lack of focus; an 18-year-old girl, whose mother is Nigerian and father African American and who was reporting depressive symptoms and confusion about sexual identity; and an 18-year-old depressed male from an Assyrian Iraqi background whose parents both are from Northern Iraq, but have lived in the United States for 20 years. Adolescents of immigrant families have much more complicated tasks during this phase of their development to establish a future sense of self-identity. A well-consolidated sense of self-identity is more complicated for these types of multiethnic immigrant families. The adolescents must rely on parental ego functions and their coherent sense of identity to weather this stage of their turbulent experience. In their strong fantasy framework, these adolescents strive to belong to their new peer groups, in which parents do not belong, particularly when the immigrant parents present a variety of different social and cultural values discordant to the contemporary culture. The cases suggest that both positive and negative aspects of ethnic identification become diluted during adolescence, when identification with parental mores occurs.

Adolescent↗
PubMed1989

Predictability of demographic variables in the short run.

In assessing the performance of population forecasts, it is useful to have a standard with which forecast errors can be compared. Univariate time series models may provide such a standard. Mean forecast errors of time series models indicate to what extent the movement of a variable could have been predicted from its own past. These errors show the degree of predictability that is attainable, at least in a given period. In this paper 3 time series methods (exponential smoothing, Box-Jenkins method, and structural time series models) are applied to Dutch data on births, deaths, marriages, immigrants, and emigrants. The variability of prediction errors between different periods is examined. The possibility that univariate predictions can be improved by using quarterly or monthly data instead of annual data is tested.

Demography↗
PubMed1985

Migration and education subsidies by governments: a game-theoretic analysis.

This study is concerned with the implications of the brain drain. "The brain drain alters both the endowments of educated labor and the cost of increasing the endowment of such labor in both countries of immigration and emigration." It thus affects government subsidies for education both directly and indirectly. "This has implications for the burden of education expenditures and net supplies of educated labor in a world with a brain drain. The [author] shows the need for inclusion of a mechanism for transfers between the involved governments if a compensation scheme is to yield Pareto efficient migration."

Demography↗
PubMed1992

Immigration and immigrant generations in population projections.

This paper proposes a new model for population projections. This model projects an initial population under conditions of fertility, mortality, and international migration (like standard cohort-component models), but considers the population arrayed by generation. The model incorporates 4 generations: a foreign-born first generation (the immigrants), a second generation (sons and daughters of immigrants), a third generation (grandsons and granddaughters of immigrants), and fourth-and-higher generations. The model requires fertility, mortality, and migration equations by generation, which take a somewhat different form than in conventional cohort-component population projection. Consideration of the model also makes apparent that assignment of births to generations may not follow a simple form: the paper presents a method for including the empirical description of intergenerational births within the generational framework. As an example, the authors examine the next century of population growth for the Asian, Black, Hispanic, and White non-Hispanic populations in the US, comparing their growth rates and their composition within the total US population. With annual net immigration of 950,000, the total US population of 249 million in 1990 will top 400 million in 2070 and reach about 432 million in 2090. Thus, the level of immigration and emigration assumed in these projections suggests considerable population growth for the next hundred years. The racial/ethnic composition of the US will shift markedly during the next century, as described in the paper.

Americas↗
PubMed1988

Government policies and international migration of skilled workers in Sub-Saharan Africa.

The relationship between the international migration of skilled labor and government policies affecting migration both directly and indirectly in Sub-Saharan Africa is explored. "At an intercontinental scale the deleterious effects of the global division of labour have not merely been passively accepted; within the continent new patterns of skilled-labour migration have been created by increasingly differentiated economic performance and political relationships. A case study of Kenya, a country of small current net immigration of skilled workers, is used to specify some of the processes that establish the relationships between immigration and emigration policies, and how these have been mediated by conditions for skilled workers."

Africa↗
PubMed1975

Measuring change in sex composition.

The present paper deals with changes over time in the sex composition of a given population. Such changes are generated by the components of population change: natality, mortality, immigration and emigration. The objective of this paper is to propose a model which provides a quantitative statement concerning the effect of each such component on the change in the sex composition of the population. It is shown that the model is applicable to the measurement of sex composition by either the masculinity proportion of the sex ratio. To demonstrate the application of the proposed model, an example based on Canadian data is given.

Birth Rate↗
PubMed1992

[Consequences of international migration for Austria. Population scenarios until 2031].

"The consequences of international immigration on population development and the labour market [in Austria] are assessed on the basis of four scenarios of possible political and economic developments in Europe. In case of massive immigration (net +50,000 per year) the residential population of Austria...will grow to 9.5 million within 40 years.... With a net immigration of +25,000 persons per year the residential population will grow to 8.3 inhabitants.... Without any immigration or with immigration and emigration of equal proportion, the population of Austria will shrink to somewhat above 7.1 million...." (SUMMARY IN ENG)

Austria↗
PubMed1995

Zero net international migration: what does it really mean?

"The idea of ¿zero net migration' is gaining increasing currency. It has been assumed that if there is balance between the number of immigrants and emigrants, migration will have no impact on a country's population size. However, this article demonstrates that zero net migration is not necessarily the same as zero migration, and can result in a higher population than would have occurred without any migration at all." The examples of Germany and the United States are presented.

Americas↗
PubMed1986

Immigrant workers in an emigrant economy: an examination of replacement migration in the Middle East.

The author investigates human resource shortages in a labor-supplying country, focusing particularly on the case of Jordan. He "examines the growth, characteristics and role of immigrant labour in an erstwhile emigrant economy and assesses the validity of the replacement migration model. Data is presented from the author's survey of some 3,751 work permits issued to foreign workers in Amman between October 1982 and January 1983." It is noted that "replacement migration is only one aspect of a more diffuse pattern of labour inflows which have important implications for the Jordanian economy in general and the labour market in particular." In addition to replacement labor migration, which involves the employment of skilled workers in sectors experiencing domestic labor shortages, the author identifies the roles played by collective contract labor, involving immigrant labor for project-specific work, and secondary labor, involving low-skill work at discriminatory wage rates. The distinctions between these forms of labor migration and their economic implications are discussed. (SUMMARY IN FRE AND SPA)

Asia↗
PubMed1982

Estimating the emigration rates of legal immigrants using administrative and survey data: the 1971 cohort of immigrants to the United States.

Based on administrative and survey data as well as data-based assumptions about the bounds on alien address reporting, this study provides estimates of the lower and upper bounds for the cumulative net emigration rates, by country and area of origin, of the FY1971 cohort of legal immigrants to the United States as of January 1979. The merged data indicate that the cumulative net emigration rate for the entire cohort could have been as high as 50 percent. Canadian emigration was probably between 51 and 55 percent. Emigration rates for legal immigrants from Central America, the Caribbean (excluding Cuba), and South America were at least as high as 50 percent, and could have been as high as 70 percent. Emigration rates for Koreans and Chinese could not have exceeded 22 percent over the same period.

Demography↗
PubMed2006

Dynamics of mutualist populations that are demographically open.

1. Few theoretical studies have examined the impact of immigration and emigration on mutualist population dynamics, but a recent empirical study (A.R. Thompson Oecologia, 143, 61-69) on mutualistic fish and shrimp showed that immigration can prevent population collapse, and that intraspecific competition for a mutualistic partner can curb population expansion. To understand in a theoretical context the implications of these results, and to assess their generality, we present a two-species model that accounts explicitly for immigration and emigration, as well as distinguishing the impacts of mutualism on birth rates, death rates and habitat acquisition. 2. The model confirms that immigration can stabilize mutualistic populations, and predicts that high immigration, along with enhanced reproduction and/or reduced mortality through mutualism, can cause population sizes to increase until habitat availability curbs further expansion. 3. We explore in detail the effects of different forms of habitat limitation on mutualistic populations. Habitat availability commonly limits the density of both populations if mutualists acquire shelter independently. If a mutualist depends on a partner for habitat, densities of that mutualist are capped by the amount of space provided by that partner. The density of the shelter-provider is limited by the environment. 4. If a mutualism solely augments reproduction, and most locally produced individuals leave the focal patch, then the mutualism will have a minimal effect on local dynamics. If the mutualism operates by reducing rates of death or enhancing habitat availability, and there is at least some immigration, then mutualism will affect local dynamics. This finding may be particularly relevant in marine systems, where there is high variability (among species and locations) in the extent to which progeny disperse from natal locations. 5. Overall, our results demonstrate that the consequences of immigration and emigration for the dynamics of mutualists depend strongly on which demographic rate is influenced by mutualism. 6. By relating our model to a variety of terrestrial and aquatic systems, we provide a general framework to guide future empirical studies of the dynamics of mutualistic populations.

Animal Migration↗
PubMed2006

Combining demographic and count-based approaches to identify source-sink dynamics of a threatened seabird.

Identifying source-sink dynamics is of fundamental importance for conservation but is often limited by an inability to determine how immigration and emigration influence population processes. We demonstrate two ways to assess the role of immigration on population processes without directly observing individuals dispersing from one population to another and apply these methods to a population of Marbled Murrelets (Brachyramphus marmoratus) in California (USA). In the first method, the rate of immigration (i) is estimated by subtracting local recruitment (recruitment from within the population due to reproduction) estimated with demographic data from total recruitment (f; recruitment from within the population plus recruitment from other populations) estimated using temporal symmetry mark-recapture models developed by R. Pradel. The second method compares population growth rates estimated with temporal symmetry models (lambdaTS) and/or population growth rates estimated from counts of individuals over multiple sampling periods (lambdaC) with growth estimates from a stage-structured projection matrix model (lambdaM). Both lambdaTS and lambdaC incorporate all demographic processes affecting population change (birth, death, immigration, and emigration), whereas matrix models are usually constructed without incorporating immigration. Thus, if lambdaTS and lambdaC are > or = 1 and lambdaM < 1, the population is sustained by immigration and is considered to be a sink. Using the first method, recruitment estimated with temporal symmetry models was high (f= 0.182, SE = 0.058), the mean adult birth rate, as estimated using the ratio of juveniles to > or = 1 year old individuals (observed during ship-based surveys) was low (bA = 0.039, SE = 0.014), and immigration was 0.160 (SE = 0.057). Using the second method, murrelet numbers in central California were stable (lambdaC = 1.058, SE = 0.047; lambdaTS = 1.064, SE = 0.033), but were projected to decline 9.5% annually in the absence of immigration (lambdaM = 0.905, SE = 0.053). Our results suggest that Marbled Murrelets in central California represent a sink population that is stable but would decline in the absence of immigration from larger populations to the north. However, the extent to which modeled immigration is due to permanent recruitment or temporarily dispersing individuals that simply mask population declines is uncertain.

Animals↗
PubMed1986

[Waves in demographic time series].

"This article examines whether births, deaths and marriages since 1840, and immigrants and emigrants since 1900 in the Netherlands exhibit regular cycles. For this purpose spectral analysis is applied to the series of annual numbers per 1,000 inhabitants after removal of a long-term trend. The trend is estimated by fitting a cubic spline function." It is shown that "both births and marriages show a cycle of more than 20 years. Deaths do not exhibit a clear-cut cyclical pattern. Both immigration and emigration show a long cycle of about 20 years and a shorter one of 5 to 8 years." Different cycles are evident if the examination is limited to post-World War II data. "It should be emphasized, however, that all these cycles explain only a limited fraction of the total variation in the series." (SUMMARY IN ENG)

Demography↗
PubMed2004

Influence of food availability on demography and local population dynamics in a long-lived seabird.

Few studies have addressed the effects of food availability as a proximate factor affecting local adult survival in long-lived organisms and their consequences at local population dynamics. We used capture-recapture analysis of resightings of 10 birth cohorts of ringed Audouin's gulls, Larus audouinii, to estimate adult survival and dispersal (both emigration and immigration). For the first time, permanent emigration (the transient effect in capture-recapture analysis) was modelled for the whole population and not only for the newly marked birds. Gulls exploit to a large extent fishes discarded from trawlers, and a trawling moratorium established since 1991 has decreased food supply for the colony. This was used as a natural experiment of food availability to assess its effects on adult survival and emigration. These and other demographic parameters were used in a projection modelling to assess the probabilities of extinction of the colony under two scenarios of lower and higher food availability. Food availability (together with the age of individuals) influenced emigration probabilities, but not adult survival, which was estimated at 0.91 (s.e. = 0.02). When food was in shorter supply during the chick-rearing period, emigration was very high (ca. 65%) for younger breeders, although this rate decreased sharply with age. Probabilities of extinction were very high when food availability was low, and when environmental stochasticity was introduced, and only stochastic immigration from the outside seemed to prevent extinction. The results highlight the importance of dispersal processes in the population dynamics of long-lived organisms.

Animal Nutritional Physiological Phenomena↗