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German-based African Immigrants' Transnational Sphere: Strategies of Incorporation and the Creation of Identity in an Expanded European Union : African Immigrants' Incorporation
No full textThere is an upsurge interest to understand the difficulties of European integration in particular as well as the European Union in general. The fact that discussions on integration and new integration programs in Germany continue, suggest that immigrants are not yet integrated. In particular, the case of African immigrants has been neglected, especially of those who recently arrived in Germany and of those who ask for asylum. The traditional approach which provides German language courses and later offers assistance in job search can often not fully capture the immigrants’ needs. It can be observed that African immigrants have shifted from integration strategies to incorporation strategies. Integration in a traditional sense seems useful to this group, but it does not serve their goal of a permanent immigration to Germany. The latter can only be achieved through a lasting intertwining (incorporation) of their life in Germany and in their home country. Immigration can be understood as a rite of passage with a life cycle in itself which demands a redefinition of the immigrant’s goals in the respective social context. This study explores the different incorporation strategies African immigrants use to influence their residence status so that they can stay in Germany in the long-term. The study identifies marriage and family formation as social, self-employment as economic and joining ethnic associations/organizations as identity creating strategies of African immigrants. It focuses on the reasons for the choice of a particular strategy and sheds light on the process of incorporation, the immigrants’ experiences as well as the impact of the chosen strategy onto their status. Those factors are contrasted with the expectations and ambitions at the outset of migration. This research relates societal conditions with personal factors which underlie the process of status change to a permanent residence permit. The empirical basis of this study is an extend¬ed case study with 42 participants consisting of interviews and observations (supplemented by footage analysis). The analysis reveals several patterns of the different incorporation strategies which can all be subordinated under the goal of a permanent residence permit with simulta¬neous transnational intertwining. Subjective evaluations of the different strategies, their functions and the respective problems in daily life are central to this study. The findings are relevant for a politically stable Germany in the 21st century in a globalized world in context of the enlargement of the European Union. They foster the understanding of integration and incorporation mechanisms of African immigrant (groups) and provide important information for the advancement of a law concerning foreigners targeting at a successful integration.Es gibt ein vermehrtes Interesse daran, Problemlagen der Europäischen Integration und der Europäischen Union insgesamt zu verstehen. Die Tatsache, dass Diskussionen über Integration und neue Integrationsprogramme in Deutschland anhalten, weist darauf hin, dass Einwanderer nicht wirklich integriert sind. Besonders afrikanische Immigranten wurden hierbei vernachlässigt, und zwar vor allem diejenigen, die gerade in Deutschland angekommen sind und um Asyl bitten. Der traditionelle Ansatz, bei dem die Integration von Einwanderern durch Deutsch-Kurse und etwas später durch Hilfe bei der Arbeitssuche unterstützt wird, kann die Bedürfnisse von Immigranten oft nicht wirklich befriedigen. Bei afrikanischen Einwanderern ist eine Abwendung von Strategien der Integration hin zu Strategien der Inkorporation zu beobachten. Integration in einem traditionellen Sinne erscheint ihnen zwar nützlich, dient jedoch nicht ihrem Ziel der dauerhaften Einwanderung nach Deutschland. Letzteres lässt sich nur durch eine nachhaltige Verflechtung (Inkorporation) von Lebenswegen in Deutschland und im Herkunftsland erreichen. Immigration kann als Übergangsritus mit eigenem Lebenszyklus verstanden werden, der von den betreffenden Personen eine Neudefinition ihrer Ziele im jeweiligen sozialen Kontext fordert. Die hier vorgelegte Studie untersucht unterschiedliche Eingliederungsstrategien afrikanischer Einwanderer, mit denen diese ihren Aufenthaltsstatus so beeinflussen, dass sie auf lange Sicht in Deutschland bleiben können. Die Studie identifiziert Heirat und Familiengründung als soziale, selbständige Geschäftstätigkeit als ökonomische sowie den Beitritt zu ethnischen Vereinen/Organisationen als identitätsstiftende Strategien afrikanischer Immigranten. Sie fokussiert auf die Gründe für die Wahl einer bestimmten Strategie und beleuchtet dabei den Prozess der Inkorporation, die dabei gemachten Erfahrungen und deren Auswirkungen auf den Status der Immigranten und kontrastiert diese mit deren Vorstellungen und Wünschen zu Beginn des Migrationsprozesses. Die Arbeit setzt gesellschaftliche Bedingungen mit personalen Faktoren in Beziehung, die dem Prozess der Statusveränderung hin zu einer dauerhaften Aufenthaltsgenehmigung zugrunde liegen. Empirische Basis der Studie ist eine erweiterte Fallstudie mit insgesamt 42 Personen, in der u.a. Interviews und Feldbeobachtungen (ergänzt um die Analyse von Bildmaterial) durchgeführt wurden. Die Analyse ergab unterschiedliche Muster der verschiedenen Inkorporationsstrategien, die sich allerdings sämtlich dem Ziel einer unbefristeten Aufenthaltsgenehmigung bei gleichzeitiger transnationaler Verflechtung unterordnen. Subjektive Einschätzungen der verschiedenen Strategien, ihrer Funktionen und der mit Ihnen verbundenen Alltagsprobleme stehen im Zentrum der Studie. Die Ergebnisse sind in einer globalisierten Welt für ein politisch stabiles Deutschland im 21. Jahrhundert im Kontext der Erweiterung der Europäischen Union relevant. Sie fördern das Verständnis von Integrations- bzw. Inkorporationsmechanismen von afrikanischen Einwanderer(gruppe)n und liefern wichtige Hinweise für die Weiterentwicklung eines auf erfolgreiche Integration gerichteten Ausländerrechts
Subjective Physical Age and its Role in Health Behavior Change Strategies for Physical Activity
No full textWith an increasing age levels of physical activity tend to decrease, though maintaining a healthy and active lifestyle is a crucial factor in the prevention of severe chronic diseases. Due to this it is of great importance to understand age-related changes and maintenance of behaviors such as physical activity. Effects of chronological age on processes of health behavior change are well documented, but probably fail to demonstrate the impact of aging comprehensively. Therefore, other age-related factor should be investigated which might provide new insights in the adoption and maintenance of physical activity throughout the life-span.
The primary goal of this dissertation was to introduce subjective physical age as a facet of subjective age and investigate its additional value in the prediction of physical activity while focusing on intentional processes. The second goal was to highlight self-regulatory processes which aid the transition of intentions into behavior, in the light of subjective physical age. Furthermore, differences in social-cognitive predictors and their interplay were investigated.
Results from this dissertation suggest that subjective physical age contributes to in the explanation of physical activity, even when controlling for strong correlates of subjective age (health status & chronological age). Those who feel physically younger indicate higher levels of physical activity. Feeling physically younger is also related to better self-regulatory planning skills which help to translate intentions in actual behavior. Finally, results provide insights in differing cognitions regarding health behavior change predictors and mechanisms between those who feel physically younger, as old as they are, and older.
These findings are of special interest, as subjective physical age can be intervened upon to change cognitions about own ageing and age-related, physical capabilities in health behavior change interventions. They also provide a new proxy to tailor content towards the characteristics of participants in tailored, web-based health behavior change interventions to further personalize content (e.g., in web-based interventions for rehabilitation patients)
Sketch-Based Interactive Segmentation and Segmentation Editing for Oncological Therapy Monitoring
No full textA tumor’s change in size is an important criterion for assessing its response to chemotherapy. The current gold standard for measuring the size of solid tumors and their progression over time is the maximum diameter. A diameter is not always appropriate, though, since most tumors grow and shrink irregularly in 3D. Therefore, the volume of a tumor has shown to be a more accurate and reproducible measure for tumor size. In order to measure a tumor's volume based on CT, it needs to be delineated in the 3D image, which is known as the segmentation problem. The aim of this thesis is to investigate methods for interactive segmentation and editing of segmentation results in order to support the radiologist in efficiently and reliably measuring a tumor's volume in follow-up examinations. For interactive 3D segmentation, this thesis proposes a general image-independent algorithm that utilizes an object reconstruction approach. To allow an efficient 3D editing of automatically generated, insufficient segmentation results, an image-based as well as an image-independent method are suggested. All segmentation algorithms discussed in this thesis are based on an intuitive sketching interface, i.e., a user interaction in the contour domain. Evaluating algorithms for segmentation editing is challenging, because their quality depends on the user's subjective impression. This thesis discusses the evaluation of segmentation editing algorithms. In order to objectively and comprehensively evaluate segmentation editing algorithms, a qualitative rating-scheme as well as a score that accumulates the quality of intermediate segmentation results are proposed. To allow a more reproducible evaluation without the need for a user, a simulation-based evaluation approach is investigated as well. As CT images suffer from partial volume effects caused by their limited spatial resolution, the delineation of a tumor is an ill-defined problem. Particularly for interactive segmentation methods, this can result in significant differences in the volume measured by different readers or at different points of time. In order to increase the accuracy and reproducibility of volumetric measurements, a fast method for compensation of partial volume effects is proposed that utilizes the information of a given segmentation result
Investigation of The Local and Global Effects of The Analogue and Digital Mode of Genetic Regulation in Escherichia coli
No full textA lot of vital postulations were made at the dawn of genetics, even before the elucidation of the DNA structure – what is a gene, where is it located within the cell, how is it used as an information carrier? Nowadays, the questions have become exponentially more complex and understanding the mechanisms of genetic regulation is at hand. The road that scientific advancement took, specifically the early comprehension of proteins as a driving force of biological processes, left a mark on the study of genetics. It aided the identification of a plethora of DNA-binding proteins and elucidated their involvement in the replication, transcription and organisation of the molecule. In parallel, further research partially revealed the internal organization of the DNA and we gained knowledge of the genetic code of a remarkable number of organisms via sequencing entire genomes. All this information, however, should be coupled to another property of the DNA – its structure. Studies on DNA architecture revealed the existence of higher order structures that exert global control of transcriptional activity through variations of DNA topology, or the analogue mode of regulation. Here I address the importance of gene position in the bacterial chromosome by carrying out the first systematic gene relocation study in which I show that the relocation of a gene encoding for the abundant regulatory protein FIS leads to global changes in the bacterial phenotype. In order to make a fair assessment of those global positioning effects, I first carried out an in-depth investigation of the local regulation of the fis promoter region, which unveiled that RNA polymerase can serve as an architectural factor modulating the activity of transcription initiation complexes in an enhancer-like fashion. These two observations, regarding the global gene order and the complex local interactions are a step towards implementing a holistic methodology into the study of the DNA organization and dynamics
Element partitioning in foraminifera and implications for calcification
No full textPaleo-oceanographers use element to calcium ratios of foraminiferal tests to reconstruct past climate conditions. Calcite Mg/Ca is used to reconstruct past seawater temperatures. In addition to temperature Mg/CaSW also influences Mg/CaCC and - although not yet shown for foraminifers – Sr/CaCC. To reliably use such proxy relationships it is necessary to understand calcification mechanisms. Here we culture two benthic foraminifers at different seawater [Mg] and [Ca]. Growth rates are monitored during the culture experiment. Organic matter is removed with the bleaching agent NaOCl and test weight as well as calcite Mg/Ca and Sr/Ca is analyzed with LA-ICP-MS. Results show optimal growth and test thickness at Mg/CaSW near ambient. Different timespans of bleaching or concentrations of NaOCl had no influence on element to calcium ratios. Calcite Mg/Ca increases with increasing Mg/CaSW, while the partition coefficient DMg decreases. Relative Mg/CaSW, and not the absolute [Mg] and [Ca] play the crucial role in determining growth, thickness as well as Mg/CaCC. Results allowed to test a conceptual biomineralization model by Nehrke et al. (2013) and confirmed that a mixture of transmembrane transport and passive transport via leakage or vacuolization provides the necessary ions needed for chamber formation. A refined mixing model is presented, which is based on these assumptions, but assumes a weaker ion fractionation during transmembrane transport and accounts for the Mg/CaCC and DMg observed. Results furthermore showed that increasing Mg/CaCC increases Sr/CaCC, which can be explained by stress in the crystal lattice, caused by increasing Mg2+. This stress can be compensated by additional incorporation of Sr2+. This inorganic process is not yet accounted for in the mixing model. The mixing model needs further attention in future studies to finally develop a generalized biomineralization model which can explain the incorporation of all elements into foraminiferal tests
Computational Studies on the Chemistry of Boron in Gas Phase and Solution
No full textBoron is the fifth element of the periodic table, and it can covalently bind to itself forming a variety of atomic clusters in gas phase, with peculiar structures and unusual chemical bonding. On the other hand, many chemical compounds of boron are electron-deficient, and are considered as Lewis acids, displaying reactivity in solution.
In the first part of this thesis, we investigate the electronic structures and fluxionality of boron clusters in gas phase. We employ first-principles calculations to study the structural transition from an icosahedral B12I122− to a planar B12 cluster, and the results show that the transition occurs between B12I7− and B12I5−, depending on the temperature. We also investigate the dimerization of two B12I9− anions and the unusual formation of a stable doubly charged B24I182− anion. Our DFT calculations and BO-MD simulations show that such dimerization is an exothermic process, and the formed B24I182− dimer is a stable species (up to 600 K). Finally, we address the issue of fluxionality in some planar boron clusters. We find that a variety of Bn clusters (n >10) contain fluxional units, and that fluxionality is promoted by certain structural patterns.
In the second part of this thesis, we investigate the activation of molecular hydrogen by frustrated Lewis pairs (FLPs), in which substituted boranes act as Lewis acids. In FLPs, the Lewis acids and bases are sterically hindered by the presence of bulky organic substituents, and prevent the formation of classical Lewis adducts. Interestingly, such systems were demonstrated to work for H2 activation. First-principles calculations are performed to study a series of intermolecular FLPs towards H2 activation, and we successfully explain the factors that lead to reversible, irreversible and no H2 activation by such systems. We propose a new mechanism for H2 activation by intramolecular FLPs. By comparing this new mechanism with the one reported in the literature, we conclude that our new mechanism is more reasonable
Theoretical investigation on hydrogen production using metal-oxide catalysts: TiO2 and CeO2
No full textHeterogeneous reactions catalyzed by metal oxides represent a crucial type of reaction in chemical industry, e.g. the production of hydrogen. With the rapid increase of demand in hydrogen production, less expensive and more efficient methods of hydrogen production are needed. Many new or improved metal oxides have been developed by a wide variety of experimental and theoretical investigations with the motivation of searching for catalysts with higher activity. TiO2- or CeO2-based catalysts have attracted extensive attention due to their excellent redox ability, low cost, and the high structural stability in aqueous environments. Particularly, foreign elements (e.g. Fe and Ni) have been extensively used to modify TiO2 and CeO2 host matrix to improve their catalytic activity. However, numerous observations indicate that the role of foreign elements in both oxides is complex due to the presence of native oxygen vacancy defects. In this thesis, detailed atomistic investigations on Fe-doped TiO2 rutile phase and Ni-decorated CeO2 (100) surface through density functional theory (DFT) calculations are reported
Momentum exchange between atmosphere, sea ice and ocean
No full textoai:opus.jacobs-university.de:4The Arctic is experiencing ongoing dramatic changes. The strongest evidence of these changes is in the sea ice. The ice cover showed a reduction in areal extent and total volume. Older ice is giving space to new and thinner ice, and large surface topographic elements are disappearing accompanied by an increase of melt ponds and smaller topographic features. Moreover, the sea ice, which is not a stationary cover but moves in response to external forcing, showed an increase in drift speed over the last 30 years. The ice is coupled to the ocean and the atmosphere by exchanging heat and momentum, thus changes in sea ice may affect the other two components through mechanisms that are not fully understood yet.
In the light of these recent changes, a good understanding of the factors determining the lifetime, movement and evolution of the ice is becoming necessary, together with a proper investigation of the coupling of sea ice with atmosphere and ocean. It is known that the intensity of the atmosphere-ice and ocean-ice interactions depend on the roughness of the separation interface; the roughness of the ice surface is determined by the concentration and shape of the topographic elements.
The aim of this thesis is to estimate the momentum fluxes over the entire Arctic Basin as function of sea-ice topography. The present study splits in two parts: as first the momentum fluxes between atmosphere and ice and between ice and ocean are estimated based on real topography data. Then the results are upscaled with numerical simulations. This second step allows also to evaluate the impact of a more detailed physical description of the atmosphere-ice-ocean interactions on the ocean circulation.
The study based on sea-ice topography data showed a high variability in space and time of the ice surface, such variability is then reflected in the momentum fluxes. The concentration of large and small topographic elements differs from region to region according to the age of ice and to the deformation history. In particular, this study revealed that considering only the large topographic elements is not enough to characterize the degree of deformation of an ice field and thus to evaluate the strength of the air-ice-ocean interactions.
The model study showed that by introducing a topography dependent description of the atmosphere-ice-ocean interaction, the sea ice is affected in its thickness, areal extent and drift. Moreover, changes in the ice topography affect the ocean to a large extent: the ocean shows changes not only in the surface circulation, but also in the circulation of the deeper Atlantic water. This reveals that in order to obtain correct predictions for the future of the Arctic a better description of subgrid processes, like the formation of surface roughness elements and their impact on the drag coefficients, is needed
Dicer-like proteins in Dictyostelium discoideum
No full textDicer and Drosha proteins are eukaryotic endoribonucleases that belong to the highly conserved RNase III family. Their prominent function is to cleave double stranded RNA into small RNA duplexes with 20-25 bp in size that comprise typically 2 nt 3´-overhangs. These characteristic small RNAs are recognized by cellular Argonaute proteins and mediate, by virtue of complementary base pairing with the target, posttranscriptional gene silencing, epigenetic modifications or silencing of invasive RNA such as viruses. The best studied types of such regulatory small RNAs, micro RNAs and small interfering RNAs (miRNAs and siRNAs, respectively) were also identified in the unicellular model organism Dictyostelium discoideum. The genome of this amoeba encodes for two Dicer-like proteins referred to as DrnA and DrnB that are potentially involved in the biogenesis of small RNA. However, little is known about their general properties and functions in such cellular pathways.
In this work it has been shown that the two Dicer-like proteins have despite their great similarity in domain structure different intracellular localizations that resemble plant Dicing- and animal P-bodies, respectively. The internal binding domain for double stranded RNA (dsRBD) of DrnB was further demonstrated to be not essential in miRNA processing in vivo. Instead DrnB was shown to co-localize with the dsRBD containing protein dsRBP_B, indicating that the function of DrnB in this pathway is rather established by a trans-interacting than by its internal dsRBD. Polyclonal antibodies against DrnA were raised in this work, and revealed an even expression of DrnA throughout the development of D. discoideum into a multicellular fruiting body. This antibody recognized DrnA also in a large protein complex as shown by native PAGE approaches and allowed to co-purify putative protein interaction partners. A presumably essential role of DrnA for the amoeba´s viability prevented possibly its chromosomal deletion. It was demonstrated in this study that the gene re-integrated into the genome by an unknown mechanism which appears to be based on in vivo ligation of knockout constructs and re-recombination of the gene. In a further part of the study on DrnA and DrnB, their RNase III domains were investigated with respect to their catalytic properties and substrate specificity in vitro. By the use of different RNA substrates it was shown that the recombinant domains can cleave
one strand in dsRNA molecules that comprise regions of mismatches. Perfectly base paired dsRNA or single stranded RNA, however, were not processed. This unexpectedly restricted substrate recognition contrasts the findings in experiments with Dicer in other organisms, and offers new insights into the properties of RNase III domain containing proteins which appear to be divergent in Dictyostelium.
Finally, preliminary investigations of ribosomal RNA in the drnB knockout strain revealed an accumulation of small RNAs that are derived from the 17S rRNA and its precursor. This observation suggests that DrnB participates in rRNA related pathways; however its detailed contribution awaits further examination. In summary, Dicer-like proteins in Dictyostelium seem to combine attributes from Dicer and Drosha in plants, animals and yeast: They form nuclear bodies like they do in plants, but they also assemble into cytoplasmic structures like in animals, and they finally appear to be involved in ribosomal RNA pathways like RNase III proteins in yeast. From an evolutionary perspective this reflects the phylogenetic position of the Dictyostelium lineage that branched out after plants but before animals and fungi, and may place DrnA and DrnB to an intermediate stage in the evolution of Dicer and Drosha in higher eukaryotes
Antiholomorphic Dynamics: Topology of Parameter Spaces and Discontinuity of Straightening
No full textThe goal of this thesis is to study the dynamics of unicritical antiholomorphic polynomials, and to explore the combinatorial and topological properties of the multicorns, which are the connectedness loci of the maps under consideration. We, on one hand, prove many topological differences between the multicorns and their holomorphic counterparts, the multibrot sets, and on the other hand, study the self-similarity property of the multicorns.
We show that the parameter rays accumulating on the boundaries of odd period (except period one) hyperbolic components of the multicorns do not land; they non-trivially accumulate on intervals of parabolic parameters. We also study the behavior of the ‘straightening maps’ from the ‘baby multicorns’ to the original multicorns. More precisely, we prove discontinuity of the straightening map (for even degree multicorns) at infinitely many explicit parameters. Both of these results are in stark contrast with the corresponding situation for the multibrot sets, where all rational parameter rays are known to land, and all baby multibrot sets are known to be homeomorphic to the original ones