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This thesis examines the migration policy changes that were adopted by the European Union during the so called ‘refugee crisis’ 2014-2016 and problematises the discourses that were deployed by EU policy makers. It builds the method and theoretical framework around Vivien Schmidt’s discursive institutionalism, and complements it with constructivist conceptual theories around discourses that are identified through the researched empirical material. The primary material is to a large extent based upon official documents from the EU such as regulations and communications, but also includes speeches from officials such as Jean Claude Juncker (President of the Commission), Donald Tusk (President of the Council) and Martin Schulz (President of the European Parliament). The findings are comprised of discourses that can all be connected to the EU imaginary. The thesis also concludes that there has been a continuation of the securitisation of migration during the ‘refugee crisis’ as well as a normalisation of this discourse. In regards to the communicative and coordinative skills of the EU actors, it becomes clear that the former still is problematic, whilst the coordinative discourses have increased the cooperation within the EU institutions during the time period studied.

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In 1902, the company AB Nautanens Kopparfält established its mining operation in Nautanen, located in Gällivare parish, about five kilometers from Koskullskulle. This company would be the starting point for Nautanen's community, which came to grow in a very short time into up to 400 inhabitants. This was a society that, among other things, could offer work opportunities, housing, education for the children, a community center and a doctor´s office. The focus of this thesis will be on the 142 people who had an employment registered on them in the parish registers belonging to Nautanen. Work is usually the driving force for migration processes that take place. Based on pull and push factors, the thesis highlights a migration process with respect to place of departure, age, occupation, relationship status, and the migration structure from Nautanen after the mining operations were shut down. The results of the survey showed that the job opportunities, well-paid work, better housing compared to the close by society Malmberget and an education for the children were a driving force for many choosing to move to Nautanen. Furthermore, the survey shows that a larger number of the new residents came from other places in the close by Gällivare parish and that the emigration distances were significantly longer compared to the moving-in distance. / År 1902 etablerade företaget AB Nautanens Kopparfält gruvverksamhet i Nautanen beläget i Gällivare församling, cirka fem kilometer ifrån Koskullskulle. Detta skulle vara startskottet till att ett samhälle, med uppemot 400 invånare, växte fram på väldig kort tid i anslutning till gruvan. Samhället kunde bland annat erbjuda arbetsmöjligheter, bostäder, utbildning till barnen, ett folketshus samt en provinsialläkarmottagning.Undersökningens huvudfokus kommer ligga på de 142 personer som hade ett yrke registrerat på sig i församlingsböckerna som tillhörde Nautanen. Arbete är oftast den drivande kraften till migrationsprocesser. Utifrån pull- och push faktorer belyser undersökningen en migrationsprocess med avseende på avreseort, ålder, yrke, relationsstatus, samt utflyttnings-strukturen från Nautanen efter att gruvverksamheten lagts ned. Resultatet av undersökningen visade att arbetsmöjligheter, väl avlönat arbete, bättre bostäder i jämförelse med närliggande Malmberget och en utbildning till barnen var drivande krafter till att många valde att flytta till Nautanen. Vidare visar undersökningen att en större mängd av inflyttarna kom ifrån andra platser i Gällivare församling samt att utflyttningsdistanserna var betydligt längre i jämförelse med inflyttningsdistansen.

With the transition of the economy in China, migrants start holding a more and more important position in the labor market. Therefore, from this dissertation, we try to explore different topics related to the migrants in China. This dissertation consists of three essays on who chooses to migrate, how networks affect migrants' outcomes, and what is the intergenerational impact of parental migration on children's risk preferences. In the first chapter, we briefly introduce the motivation and contribution, and then we provide the methods and detailed findings in the following chapters. Chapter 2 examines the impact of the endogeneity of the decision to migrate on the wage differentials between migrants and non-migrants in China. We find that migrants are self-selected from the upper tail of the income distribution in their home location. Consistent with a theoretical model of migration choice, we show that the size of the selection effect on wage depends on the wage differences between the prefectures of origin and destination as well as migration cost. The selection effect also differs among workers with different education and in different cities. Chapter 3 studies how networks affect migrants' migration decisions, employment, and wage levels by using 2005 China's mini-census. Different from existing studies, this paper takes into account the existence of self-selection in the labor market. With the help of a theoretical model, we have a better understanding of the mechanism of networks as well as the different network effects on rural and urban migrants. We find out that networks affect both rural and urban migrants' migration decisions positively. In terms of employment, networks exert positive impacts on rural migrants but not on urban ones, which is due to the different quality drops between rural and urban migrants when the networks increase. Such employment effects also lead rural migrants to face a more severe negative wage impact than urban migrants. Chapter 4 investigates how parental migration affects left-behind underage children's risk preferences. By focusing on migrant parent groups, we are able to estimate whether the influence of nurture could also affect children's risk preference levels or not. The findings suggest that besides the intergenerational transmission of risk preferences between parents and children, parental migrations do have an influence on girls' risk preference levels. In addition, in terms of adult children's risk-related outcomes, we are able to find a positive parental migration impact on daughters' self-employment decisions. Findings help us have a better understanding of the relevant factors of risk preferences, and also confront the impact of the separation of parents and children. / Doctor of Philosophy / Nowadays, migration becomes increasingly common and migrants take a large proportion of the labor market. With the economic development and the closer connections among regions, people are more likely to study or work outside their home locations than before. Even though there is still a strict household registration system in China, we can find the migration supporting systems are becoming established, and facilitate easier migration for more and more people. Having a better understanding of migrants helps us make better policies as well as have the labor market and society develop better. This dissertation explores who choose to migrate (Chapter 2), how the social connections or networks affect migrants' employment and wages (Chapter 3), and whether there is any intergenerational impact on migrants' children in terms of risk preferences (Chapter 4) using methods from labor economics and economic theory. We conclude that the best works tend to migrate first in the labor market, and social connections have different impacts on rural and urban migrants in terms of employment and wages. Moreover, we notice that migrant parents affect the left-behind children's risk preferences by both influences of nature and nurture. In sum, we study different topics on migrants and have a deeper understanding of how migrants are affected in the labor market as well as how migrants affect their next generations.

Cell migration is a complex physiological process that is important from embryogenesis to senescence. In vivo, the migration of cells is guided by a complex combination of signals and cues. Directed migration is typically observed when one of these cues is presented to cells as a gradient. Several studies have been conducted into directed migration on gradients that are purely mechanical or chemical. Our goal was to investigate cellular migratory behavior when cells are presented with a choice and have to choose between increasing substrate rigidity or higher protein concentration. We chose to focus on this unique environment since it recapitulates several interfacial regions in vivo. We have designed novel hydrogels that exhibit dual and opposing chemical and mechanical profiles using photo-polymerization. Our studies demonstrate that durotaxis, a well-known phenomenon, can be reversed when cells sense a steep protein profile in the opposite direction. Fibroblasts were co-cultured with macrophages to obtain an understanding on how migration occurs when two different cell types are present in the same microenvironment. First, we investigated the migratory behavior of macrophages. These cell types exhibited a statistically significant preference to move towards the rigid/low collagen region of the interface. Interestingly, fibroblasts when co-cultured with macrophages, exhibited a preference for the low modulus-high collagen region of the interface. However, with the current sample size, these trends are statistically insignificant. On the contrary, the presence of fibroblasts in the cellular microenvironment did not result in the reversal of durotaxis exhibited by macrophages. Macrophages secreted significantly higher levels of secreted tumor necrosis factor (TNF-alpha) in mono-cultures in contrast to fibroblast-macrophage co-cultures. This trend could be an indication of macrophage plasticity between mono- and co-cultures. In summary, we have designed dual and opposing rigidity-protein gradients on a hydrogel substrate that can provide new insights into cellular locomotion. These results can be used to design biomimetic interfaces, biomaterial implants and for tissue engineering applications. / Ph. D.

Thèse ou mémoire avec insertion d'articles / La capacité des cellules à migrer à distance de leur lieu de production est un élément clé du développement embryonnaire du cerveau. A l'âge adulte, dans le système nerveux central, la migration cellulaire est associée aux niches neurogéniques de la zone sous ventriculaire et du gyrus dentelé. Certaines conditions pathologiques ou lésions cérébrales peuvent créer un environnement pouvant attirer les précurseurs neuronaux en dehors de leurs voies habituelles de migration vers le site de lésion. Finalement, des déficits en migration durant le développement peuvent entrainer l'apparition de pathologies se traduisant par une organisation non conventionnelle des réseaux neuronaux pouvant conduire entre autres à l'apparition de troubles cognitifs ou de symptômes épileptiques. La migration des cellules est guidée par un ensemble complexe de signaux moléculaires, d'interactions physiques et de gradients électriques. C'est l'intégration de ces signaux au niveau intracellulaire qui coordonne la réponse migratoire de la cellule en modulant par exemple le cytosquelette, divers organites tels que les mitochondries ou des mécanismes tels que l'autophagie. Au cours des travaux présentés dans cette thèse, j'ai utilisé comme modèle d'étude la migration des neuroblastes dans le courant migratoire rostral, qui achemine les précurseurs neuronaux depuis la zone sous ventriculaire jusqu'au bulbe olfactif où ils intègrent les réseaux neuronaux existants. Dans le premier chapitre, je me suis intéressé à la contribution du mécanisme d'autophagie dans le contrôle de la migration cellulaire. Nous avons montré que l'autophagie est nécessaire au maintien d'une migration normale et que ce mécanisme est régulé temporellement et spatialement durant la migration. Son activation est liée au niveau énergétique intracellulaire et passe par l'activation d'AMPK, qui est le senseur d'énergie majeur de la cellule. Dans un deuxième temps, je me suis intéressé à l'impact sur la migration cellulaire de mutations des cadhérines Fat4 et Dchs1 qui entrainent chez l'humain un phénotype d'hétérotopie neuronale périventriculaire. Grâce à l'utilisation de greffes de cellules progénitrices issues de cellules humaines pluripotentes induites (dont l'acronyme anglais est iPSC) j'ai pu confirmer un défaut de migration des cellules présentant des mutations pour l'une ou l'autre de ces protéines. Pour finir nous avons aussi pu montrer que ce défaut de migration est accompagné d'une dysfonction dans le flux d'autophagie et une diminution du nombre de lysosomes disponibles. / The ability of cell to migrate away from their sites of production is a major process during embryonic and postnatal brains development allowing for a correct positioning of cells. During adulthood, in the central nervous system, cell migration is still present and, under physiological conditions, is associated with neurogenic niches of the subventricular zone and the dentate gyrus. Some pathologies or brain damaged could de-route migratory neurons away from their normal paths of migration to lesions sites. It should be also mentioned that during embryonic development, migration-associated disorders could lead to brain malformation resulting in cognitive disorder or epilepsy. Migratory behaviors of cells is determined by a complex mixture of extrinsic molecular cues, physical scaffold, or electrical gradient. The integration of these signals at the cellular level creates a coordinated response of intracellular elements like cytoskeleton, mitochondria, or autophagy. In this work, I studied the role of autophagy in neuronal migration under physiological and pathological conditions by using a migration of neuroblasts from the subventricular zone to the olfactory bulb along the rostral migratory stream as model system. In the first chapter of my thesis, I studied the contribution of autophagy in the control of cell migration under physiological conditions. We showed that autophagy is spatially and temporally regulated in migrating neuroblasts and maintains a normal rate of migratory event. This process is controlled by intracellular ATP/ADP level via the activation of AMPK In the second part of this work, I focused on mutation for paired cadherins Fat4 and Dchs1 leading to periventricular neuronal heterotopia phenotypes in humans. By grafting in the pups with NPCs derived from human iPSC with mutation form Fat4 or Dchs1, I showed default of migration in vivo of NPCs with these two mutations. We also showed that these cells exhibit altered autophagy flux associated with a decreased in lysosomal vesicles.

Glass corrodes in aqueous environments. The corrosion process is well-understood for many circumstances involving long periods of time at room temperature as well as processes that involve conventional heating, but the effect of microwave energy on glass corrosion has never been fully investigated. It was suspected that microwaves may alter or accelerate the aqueous corrosion processes that occur in glass which contribute to migration into foods or other materials. Lithium disilicate (Li2O-2SiO2) and commercial soda-lime glass were corroded using both conventional and microwave heating in this study. The results did not clearly show substantial differences in corrosion under the test conditions, but leave open the possibility of an altered mechanism in some circumstances. These findings suggest the need for testing at a lower microwave frequency, specifically 2.45 GHz. / Master of Science