In dem vorliegenden Beitrag geht es um die theoretische Modellierung und empirische Untersuchung von Kettenmigrationsprozessen. Im Mittelpunkt steht die These, dass bei der Entscheidung zur Migration neben ökonomischen Überlegungen soziale Beziehungen der Migranten von zentraler Bedeutung sind. Auf der Basis der Theorie rationaler Entscheidungen wird ein allgemeines Erklärungsmodell für die Entstehung von Kettenmigrationsprozessen vorgestellt. Soziales Kapital fungiert dabei als eine Art "missing link" zwischen individuellen Migrationsentscheidungen und resultierenden Migrationsprozessen. Anhand der empirischen Auswertung verschiedener Datenquellen konnte die Rolle von Verwandtschaftsnetzwerken bei der Immigrations- und Rückkehrentscheidung am Beispiel der italienischen Migranten in Deutschland bestätigt werden. Die Ergebnisse der empirischen Analyse werden dargelegt, darunter aufbereitete Daten der amtlichen Statistik zum Verlauf der Immigration aus Italien seit 1950 sowie eine Auswertung von Interviews mit italienischen Befragten im Rahmen des Sozioökonomischen Panels und aus einer Gemeindestudie. Insbesondere erwies sich die Rückkehr von Haushaltsmitgliedern nach Italien als die wichtigste Determinante für Remigrationsentscheidungen. Damit wird deutlich, daß bei der Untersuchung von Migrationsprozessen die soziale Einbettung der Migranten nicht ausgeblendet werden darf. / The paper contributes to the theoretical modelling and empirical testing of chain migration processes. Besides economic aspects the impact of social relations of migrants on migration decisions is emphasized. The aim was to test several hypotheses concerning the concept of social capital which have been derived from the framework of Rational Choice Theory. Social Capital is seen as a kind of "missing link" between the migration decisons of indiviuals and resulting migration processes. The impact of family networks on the migration process has been investigated applying the theory to the case of the Italian immigrants living in Germany since the 1950\'s. The results of the analysis of several kinds of data sets are presented, namely seleceted national statistics on migration and survey data from the German Socio-Economic Panel and also from a small town study. The empirical data analysis shows effects of households and family neworks on immigration and return migration as well as some evidence of chain migration. Particularly for subsequent migrants social relations play a considerable role in their migration decisions. Due to this the social embeddedness of migrants is an important factor in explaining migration processes.

The flow properties of polydimethylsiloxane (PDMS) melts at room temperature were studied by measurement of lubrication forces using an Atomic Force Microscopy (AFM) colloidal force probe. A glass probe was driven toward a glass plate at piezo drive rates in the range of 12 – 120 μm/s, which produced shear rates up to ~10⁴ s⁻¹. The forces on the probe and the separation from the plate were measured. Two hypotheses were examined: (1) when a hydrophilic glass is immersed in a flow of polymer melt, does a thin layer of water form at the glass surface to lubricate the flow of polymer and (2) when a polymer melt is subject under a shear stress, do molecules within the melt spatially redistribute to form a lubrication layer of smaller molecules at the solid surface to enhance the flow? To examine the effect of a water lubrication layer, forces were compared in the presence and the absence of a thin water layer. The presence of the water layer was controlled by hydrophobization of the solid. In the second part, the possibility of forming a lubrication layer during shear was examined. Three polymer melts were compared: octamethyltrisiloxane (OMTS, n = 3), PDMS (n _avg = 322), and a mixture of 70 weight% PDMS and 30 weight% OMTS. We examined whether the spatial variation in the composition of the polymer melt would occur to relieve the shear stress. The prediction was that the trimer (OMTS) would become concentrated in the high shear stress region in the thin film, thereby decreasing the viscosity in that region, and mitigating the shear stress. / Master of Science

The study examines the formation and development of Chinese American populations in Augusta, Savannah, and Atlanta, Georgia from the beginnings of Chinese Exclusion period through the passage of the Immigration Act of 1965. Although people of Chinese ancestry were in an ambiguous position upon their arrival in the 1880s within the black-white dyad that defined southern race relations, they were able to negotiate this system, transforming themselves from being perceived as “outsiders” before the 1940s to being treated as “honorary whites” by the late 1960s. To explore this transition, this project analyzes generational differences between immigrants and their children. Before the 1920s, the mostly Chinese immigrant male population concerned themselves with establishing viable businesses for sending remittances back to family in China and creating social institutions that helped the men cope with decades of separation from their families. The men avoided possible conflict with Jim Crow by having their businesses and residences in black or immigrant areas. Some men cultivated better relations with whites by attending Sunday schools that catered to Chinese immigrants. The mutation from “outsider” to “honorary white” status began when prosperous Chinese men started sending for wives to join them in the 1910s, thus ushering in a new pattern of planned long-term settlement in the state. Families successfully challenged the older perception by joining white churches, enrolling their children in white schools, and building social ties with white community leaders. Second generation Chinese Americans reaped the benefits of this strategy in the 1950s and 1960s by gaining access to housing in white neighborhoods, employment opportunities in white-collar occupations, and acceptance as partners in marriages with European Americans.

The study examines the formation and development of Chinese American populations in Augusta, Savannah, and Atlanta, Georgia from the beginnings of Chinese Exclusion period through the passage of the Immigration Act of 1965. Although people of Chinese ancestry were in an ambiguous position upon their arrival in the 1880s within the black-white dyad that defined southern race relations, they were able to negotiate this system, transforming themselves from being perceived as “outsiders” before the 1940s to being treated as “honorary whites” by the late 1960s. To explore this transition, this project analyzes generational differences between immigrants and their children. Before the 1920s, the mostly Chinese immigrant male population concerned themselves with establishing viable businesses for sending remittances back to family in China and creating social institutions that helped the men cope with decades of separation from their families. The men avoided possible conflict with Jim Crow by having their businesses and residences in black or immigrant areas. Some men cultivated better relations with whites by attending Sunday schools that catered to Chinese immigrants. The mutation from “outsider” to “honorary white” status began when prosperous Chinese men started sending for wives to join them in the 1910s, thus ushering in a new pattern of planned long-term settlement in the state. Families successfully challenged the older perception by joining white churches, enrolling their children in white schools, and building social ties with white community leaders. Second generation Chinese Americans reaped the benefits of this strategy in the 1950s and 1960s by gaining access to housing in white neighborhoods, employment opportunities in white-collar occupations, and acceptance as partners in marriages with European Americans.

In dem vorliegenden Beitrag geht es um die theoretische Modellierung und empirische Untersuchung von Kettenmigrationsprozessen. Im Mittelpunkt steht die These, dass bei der Entscheidung zur Migration neben ökonomischen Überlegungen soziale Beziehungen der Migranten von zentraler Bedeutung sind. Auf der Basis der Theorie rationaler Entscheidungen wird ein allgemeines Erklärungsmodell für die Entstehung von Kettenmigrationsprozessen vorgestellt. Soziales Kapital fungiert dabei als eine Art "missing link" zwischen individuellen Migrationsentscheidungen und resultierenden Migrationsprozessen. Anhand der empirischen Auswertung verschiedener Datenquellen konnte die Rolle von Verwandtschaftsnetzwerken bei der Immigrations- und Rückkehrentscheidung am Beispiel der italienischen Migranten in Deutschland bestätigt werden. Die Ergebnisse der empirischen Analyse werden dargelegt, darunter aufbereitete Daten der amtlichen Statistik zum Verlauf der Immigration aus Italien seit 1950 sowie eine Auswertung von Interviews mit italienischen Befragten im Rahmen des Sozioökonomischen Panels und aus einer Gemeindestudie. Insbesondere erwies sich die Rückkehr von Haushaltsmitgliedern nach Italien als die wichtigste Determinante für Remigrationsentscheidungen. Damit wird deutlich, daß bei der Untersuchung von Migrationsprozessen die soziale Einbettung der Migranten nicht ausgeblendet werden darf.:Einleitung; Migrationstheorien und Migrationsforschung; Handlungs- und Entscheidungstheorie; Soziales Kapital; Erklärungsmodell für Kettenmigrationsprozesse; Methoden zur empirischen Untersuchung der Kettenmigration; Ergebnisse der Analyse amtlicher Daten. Die italienischen Immigranten in Deutschland; Ergebnisse der Gemeindestudie; Ergebnisse der Sekundäranalyse der italienischen Migranten im Sozioökonomischen Panel; Schlussfolgerungen / The paper contributes to the theoretical modelling and empirical testing of chain migration processes. Besides economic aspects the impact of social relations of migrants on migration decisions is emphasized. The aim was to test several hypotheses concerning the concept of social capital which have been derived from the framework of Rational Choice Theory. Social Capital is seen as a kind of "missing link" between the migration decisons of indiviuals and resulting migration processes. The impact of family networks on the migration process has been investigated applying the theory to the case of the Italian immigrants living in Germany since the 1950\''s. The results of the analysis of several kinds of data sets are presented, namely seleceted national statistics on migration and survey data from the German Socio-Economic Panel and also from a small town study. The empirical data analysis shows effects of households and family neworks on immigration and return migration as well as some evidence of chain migration. Particularly for subsequent migrants social relations play a considerable role in their migration decisions. Due to this the social embeddedness of migrants is an important factor in explaining migration processes.:Einleitung; Migrationstheorien und Migrationsforschung; Handlungs- und Entscheidungstheorie; Soziales Kapital; Erklärungsmodell für Kettenmigrationsprozesse; Methoden zur empirischen Untersuchung der Kettenmigration; Ergebnisse der Analyse amtlicher Daten. Die italienischen Immigranten in Deutschland; Ergebnisse der Gemeindestudie; Ergebnisse der Sekundäranalyse der italienischen Migranten im Sozioökonomischen Panel; Schlussfolgerungen